阅读说明：本技术 平版印刷版原版及平版印刷版的制作方法 (Lithographic printing plate precursor and method for producing lithographic printing plate ) 是由 榎本和朗 荒木健次郎 于 2019-01-30 设计创作，主要内容包括：本发明提供一种平版印刷版原版及使用上述平版印刷版原版的平版印刷版的制作方法,上述平版印刷版原版具有支承体及形成于上述支承体上的图像记录层,上述图像记录层含有包含具有烯属不饱和基团的结构单元A1的聚合物A,上述聚合物A的重量平均分子量为2,500～35,000,上述聚合物A中的上述结构单元A1的含量为15mol％以上。(The invention provides a lithographic printing plate precursor and a method for producing a lithographic printing plate using the same, wherein the lithographic printing plate precursor comprises a support and an image recording layer formed on the support, the image recording layer contains a polymer A containing a structural unit A1 having an ethylenically unsaturated group, the weight average molecular weight of the polymer A is 2,500 to 35,000, and the content of the structural unit A1 in the polymer A is 15 mol% or more.)

1. A lithographic printing plate precursor having:

a support; and

an image recording layer formed on the support,

the image-recording layer contains a polymer A comprising a structural unit A1 having an ethylenically unsaturated group,

the weight average molecular weight of the polymer A is 2500-35000,

the content of the structural unit A1 in the polymer A is 15 mol% or more.

2. The lithographic printing plate precursor according to claim 1,

the weight average molecular weight of the polymer A is 2500-20000, and the content of the structural unit A1 in the polymer A is more than 30 mol%.

3. The lithographic printing plate precursor according to claim 1 or 2,

the content of sulfur element is 0.5 to 10% by mass based on the total mass of the polymer A.

4. The lithographic printing plate precursor according to any one of claims 1 to 3,

the polymer A is a star-shaped polymer comprising structural units derived from a polyfunctional thiol compound having 3 or more functions and 10 or less functions.

5. The lithographic printing plate precursor according to any one of claims 1 to 4,

the ethylenically unsaturated group in the polymer a is a (meth) acryloyloxy group.

6. The lithographic printing plate precursor according to any one of claims 1 to 5,

the polymer A contains a structural unit containing an ether bond as the structural unit B1 having a hydrophilic group.

7. The lithographic printing plate precursor according to any one of claims 1 to 6,

the image recording layer further includes a polymerizable compound and an electron acceptor type polymerization initiator.

8. The lithographic printing plate precursor according to any one of claims 1 to 7,

the image recording layer further comprises an infrared absorber.

9. The lithographic printing plate precursor according to any one of claims 1 to 8,

the image recording layer further comprises an acid developer.

10. The lithographic printing plate precursor according to any one of claims 1 to 9,

the image recording layer further comprises polymer particles.

11. The lithographic printing plate precursor according to any one of claims 1 to 10, which is an on-press development lithographic printing plate precursor.

12. A method of making a lithographic printing plate comprising:

a step of image-wise exposing the lithographic printing plate precursor according to any one of claims 1 to 11; and

and removing the unexposed portion of the image recording layer by at least one of a printing ink and a fountain solution.

13. A method of making a lithographic printing plate comprising:

an exposure step of exposing the lithographic printing plate precursor according to any one of claims 1 to 11 to form an image, and forming exposed portions and unexposed portions; and

and a step of removing the unexposed portions by supplying a developer having a pH of 2 to 11.

Technical Field

The present invention relates to a lithographic printing plate precursor and a method for producing a lithographic printing plate.

Background

In general, lithographic printing plates are composed of an oleophilic image portion that receives ink during printing and a hydrophilic non-image portion that receives fountain solution. Lithographic printing is a method of printing by using the property of water and oil-based ink repelling each other, in which an oleophilic image portion of a lithographic printing plate is used as an ink-receiving portion, and a hydrophilic non-image portion is used as a fountain solution-receiving portion (ink-receiving portion), and a difference in ink adhesion occurs on the surface of the lithographic printing plate, so that ink is applied only to the image portion, and then the ink is transferred to a printing object such as paper.

In order to produce such a lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Generally, a lithographic printing plate is obtained by plate making as follows: after exposure of an original such as a high-contrast film to a lithographic printing plate precursor, a portion to be an image portion of an image recording layer is left, and unnecessary image recording layers other than the image portion are removed by dissolving in an alkaline developer or an organic solvent, whereby a non-image portion is formed by exposing the surface of a hydrophilic support.

Further, due to the increasing interest in the global environment, environmental problems with waste liquid accompanying wet processing such as development processing become apparent.

Regarding the environmental problems, simplification of development or plate making and no treatment are required. As one of the simple manufacturing methods, a method called "on-press development" is performed. Namely the following method: after exposure, the lithographic printing plate precursor is directly mounted on a printing press without conventional development, and unnecessary portions of the image recording layer are removed at the initial stage of a normal printing process.

Examples of a printing method using a conventional lithographic printing plate precursor or lithographic printing plate precursor include those described in japanese patent laid-open nos. 2012 and 148555 and 2017 and 154318.

Jp 2012-148555 a describes a lithographic printing plate precursor having, on a support, an image recording layer containing a binder, a radical polymerizable compound, and a radical polymerization initiator, wherein the binder has a polymer chain having a polymerizable group, the polymer chain having a core of a multifunctional thiol having 6 to 10 functions and bonded to the core via a thioether bond.

Jp 2017 a-154318 discloses a printing method comprising the steps of: an on-press development type lithographic printing plate precursor having at least one constituent layer on an aluminum support mounted on the same plate cylinder of a printing press, the on-press development type lithographic printing plate dummy having at least one of the constituent layers containing a low-molecular hydrophilic compound, and having on the aluminum support an image recording layer containing a polymerization initiator including an organoboron-containing anion, is subjected to on-press development.

Disclosure of Invention

Technical problem to be solved by the invention

Among lithographic printing plates, there is a demand for lithographic printing plates having an excellent number of printing plates (hereinafter, also referred to as "brushing resistance").

The present inventors have found that the lithographic printing plate precursor according to the present invention can further improve the brushing resistance than the lithographic printing plate precursor described in japanese patent laid-open nos. 2012 and 148555 or 2017 and 154318.

An object of an embodiment of the present invention is to provide a lithographic printing plate precursor having excellent printing durability and a method for making a lithographic printing plate using the lithographic printing plate precursor.

Means for solving the technical problem

The means for solving the above problems include the following means.

< 1 > a lithographic printing plate precursor comprising a support and an image-recording layer formed on the support, wherein the image-recording layer contains a polymer A containing a structural unit A1 having an ethylenically unsaturated group, the weight-average molecular weight of the polymer A is 2,500 to 35,000, and the content of the structural unit A1 in the polymer A is 15 mol% or more.

< 2 > the lithographic printing plate precursor according to the above < 1 >, wherein,

the weight average molecular weight of the polymer A is 2,500-20,000, and the content of the structural unit A1 in the polymer A is more than 30 mol%.

< 3 > the lithographic printing plate precursor according to the above < 1 > or < 2 >, wherein,

the content of sulfur element is 0.5 to 10% by mass based on the total mass of the polymer A.

< 4 > the lithographic printing plate precursor according to any one of the above < 1 > to < 3 >, wherein,

the polymer A is a star-shaped polymer containing a structural unit derived from a polyfunctional thiol compound having 3 or more functions and 10 or less functions.

< 5 > the lithographic printing plate precursor according to any one of the above < 1 > to < 4 >, wherein,

the ethylenically unsaturated group in the above-mentioned polymer A is a (meth) acryloyloxy group.

< 6 > the lithographic printing plate precursor according to any one of the above < 1 > to < 5 >, wherein,

the polymer a contains a structural unit containing an ether bond as the structural unit B1 having a hydrophilic group.

< 7 > the lithographic printing plate precursor according to any one of the above < 1 > to < 6 >, wherein,

the image recording layer further contains a polymerizable compound and an electron acceptor type polymerization initiator.

< 8 > the lithographic printing plate precursor according to any one of the above < 1 > to < 7 >, wherein,

the image recording layer further contains an infrared absorber.

< 9 > the lithographic printing plate precursor according to any one of the above < 1 > to < 8 >, wherein,

the image recording layer further contains an acid developer.

< 10 > the lithographic printing plate precursor according to any one of the above < 1 > to < 9 >, wherein,

the image recording layer further contains polymer particles.

< 11 > the lithographic printing plate precursor according to any one of the above < 1 > to < 10 > which is a lithographic printing plate precursor for on-press development.

< 12 > a method for producing a lithographic printing plate, comprising:

a step of image-exposing the lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 11 >; and

and removing the unexposed portion of the image recording layer by printing at least one of ink and fountain solution.

< 13 > a method for producing a lithographic printing plate, comprising:

an exposure step of exposing the lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 11 > in an image form, and forming exposed portions and unexposed portions; and

and a step of removing the unexposed portion by supplying a developer having a pH of 2 to 11.

Effects of the invention

According to the embodiments of the present invention, a lithographic printing plate precursor having excellent printing durability and a method for making a lithographic printing plate using the lithographic printing plate precursor can be provided.

Detailed Description

The present invention will be described in detail below. The following description of the constituent elements may be made in accordance with a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

In the present specification, "to" indicating a numerical range is used in a sense of including numerical values described before and after the range as a lower limit value and an upper limit value.

In the labels of the groups (radicals) in the present specification, the unsubstituted and substituted labels also include the unsubstituted and substituted groups. For example, "alkyl" includes not only alkyl having no substituent (unsubstituted alkyl), but also alkyl having a substituent (substituted alkyl).

In the present specification, "(meth) acrylic acid" is a term used in a concept including both acrylic acid and methacrylic acid, and "(meth) acryloyl group" is a term used in a concept including both acryloyl group and methacryloyl group.

The term "step" in the present specification is not limited to an independent step, and is also included in the term as long as the intended purpose of the step is achieved even when the step cannot be clearly divided from other steps. In the present invention, "mass%" is defined as the same as "weight%" and "parts by mass" is defined as the same as "parts by weight".

In the present invention, the amount of each component in the composition means the total amount of a plurality of substances present in the composition, unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition.

In the present invention, a combination of 2 or more preferred embodiments is a more preferred embodiment.

Also, unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present invention are molecular weights converted by Gel Permeation Chromatography (GPC) analysis by a column using TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation) and detected by a solvent THF (tetrahydrofuran), a differential refractometer, and polystyrene as a standard substance.

In the present invention, the term "lithographic printing plate precursor" includes not only lithographic printing plate precursors but also waste printing plate precursors. The term "lithographic printing plate" includes not only a lithographic printing plate produced by exposing and developing a lithographic printing plate precursor as needed, but also a waste plate. In the case of a waste plate precursor, the operations of exposure and development are not necessarily required. The waste plate is a lithographic printing plate precursor to be mounted on an unused plate cylinder when printing a part of a paper surface in monochrome or 2 colors in color newspaper printing, for example.

In the present invention, an "+" in the chemical structural formula represents a bonding position with another structure.

The present invention will be described in detail below.

(original plate of lithographic printing plate)

The lithographic printing plate precursor of the present invention comprises a support and an image recording layer formed on the support, wherein the image recording layer contains a polymer A containing a structural unit A1 having an ethylenically unsaturated group, the weight average molecular weight of the polymer A is 2,500 to 35,000, and the content of the structural unit A1 in the polymer A is 15 mol% or more.

The lithographic printing plate precursor according to the present invention can be preferably used as an on-press development lithographic printing plate precursor.

As a result of intensive studies, the present inventors have found that a lithographic printing plate precursor excellent in the brushing resistance can be provided by adopting the above-described structure.

The detailed mechanism for obtaining the above-described effects is not clear, but is presumed to be as follows.

In the lithographic printing plate precursor described in japanese patent laid-open nos. 2012 and 148555 or 2017 and 154318, in order to further improve the brushing resistance, it is considered to increase the amount of the crosslinkable group of the polymer (binder polymer) contained in the image recording layer. However, according to the study of the present inventors, the brush resistance was not significantly improved only by increasing the amount of the crosslinkable group.

Accordingly, the present inventors have conducted intensive studies and as a result have found that the amount of crosslinkable groups in the polymer a used in the present invention is increased and the weight average molecular weight of the polymer a is reduced, thereby significantly improving the brush resistance.

This is presumably because lowering the molecular weight of the polymer a increases the compatibility of other components such as a polymerizable compound added to the image recording layer with the polymer a, and the effect of densification of the crosslinked structure is more likely to be exhibited by increasing the amount of crosslinkable groups.

Further, it is considered that the influence of the interatomic interaction such as the interaction between S (sulfur atom) and O (oxygen atom) is large with respect to the increase in the content of sulfur element in the polymer a by lowering the molecular weight of the polymer a, and therefore, the mechanism of improving the brush resistance is involved.

In recent years, as an ink for printing, an ink that is cured by irradiation of Ultraviolet (UV) (also referred to as an "ultraviolet-curable ink") is sometimes used.

Ultraviolet-curable inks have advantages such as high productivity due to instantaneous drying, easy reduction of environmental pollution due to a small amount of solvent or no solvent, and an expanded range of applications such as printing because images can be formed without thermal drying or thermal drying in a short time.

Therefore, it is considered that a lithographic printing plate capable of providing a lithographic printing plate excellent in the brushing resistance (hereinafter, also referred to as "UV brushing resistance") when an ultraviolet curable ink is used is extremely useful for production.

In the present invention, the brushing resistance when a normal oil-based ink is used instead of the ultraviolet-curable ink is simply referred to as "brushing resistance" or "oil-based brushing resistance".

The present inventors have found that UV resistance is easily improved in the lithographic printing plate precursor according to the present invention. The detailed mechanism of obtaining the above-mentioned effects is not clear, but it is presumed that the effect of densification in which a crosslinked structure is easily developed and the effect of an interatomic interaction such as an S — O interaction become large, similarly to the improvement of the above-mentioned brush resistance.

In addition, in the case of performing on-press development in particular, in a printed matter obtained using a lithographic printing plate after development, print stains (hereinafter, also referred to as "Spot scum") having a small area (for example, a diameter of 20 μm to 2,000 μm) such as a dot shape or a ring shape may be generated.

The reason why the above-mentioned mottled dirt is caused is presumed to be as follows: for example, the removal of the image recording layer by development is insufficient (a local residual film is formed) because the polymer is formed in the etched portion due to the local corrosion in the aluminum support.

As a result of intensive studies, the inventors of the present invention have found that the lithographic printing plate precursor of the present invention is easy to suppress the occurrence of the above-mentioned mottled stains after development.

This is presumably because, since the polymer a has a low molecular weight, the molecular weight of the polymer formed as described above is relatively small, and hence the removability of the residual film by development is improved.

As a result of intensive studies, the inventors of the present invention have found that the lithographic printing plate precursor of the present invention is easy to improve on-press developability.

This is presumably because the polymer a has a low molecular weight, and thus the non-image portion can be easily removed by on-press development.

Hereinafter, the details of each constituent element of the lithographic printing plate precursor according to the present invention will be described.

< support >

The lithographic printing plate precursor of the present invention has a support.

As the support, a support having a hydrophilic surface (also referred to as "hydrophilic support") is preferable. As the hydrophilic surface, a contact angle with water is preferably less than 10 °, more preferably less than 5 °.

The support for the lithographic printing plate precursor according to the present invention can be suitably selected from known supports for lithographic printing plate precursors and used. As the support, an aluminum plate roughened by a known method and anodized is preferable.

The aluminum plate may be further subjected to surface hydrophilization treatment by alkali metal silicate as described in each of the specifications of U.S. Pat. nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734, or surface hydrophilization treatment by polyvinylphosphonic acid or the like as described in each of the specifications of U.S. Pat. nos. 3,276,868, 4,153,461 and 4,689,272.

The center line average roughness of the support is preferably 0.10 to 1.2 μm.

The support may have a back coat layer of an organic polymer compound described in Japanese patent application laid-open No. 5-045885, or a silicon-containing alkoxide compound described in Japanese patent application laid-open No. 6-035174, on the surface opposite to the image recording layer, as necessary.

< image recording layer >

The lithographic printing plate precursor according to the present invention has an image recording layer formed on a support.

The image recording layer used in the present invention is preferably a negative image recording layer, more preferably a water-soluble or water-dispersible negative image recording layer.

From the viewpoint of brush resistance and photosensitivity, the image recording layer used in the present invention preferably further contains an electron acceptor type polymerization initiator and a polymerizable compound.

The image recording layer used in the present invention preferably further contains an infrared absorber from the viewpoint of exposure sensitivity.

In order to confirm the exposed portion before development, the image recording layer used in the present invention preferably further contains an acid developer.

In the lithographic printing plate precursor according to the present invention, it is preferable that the unexposed portion of the image-recording layer can be removed by at least one of a fountain solution and a printing ink from the viewpoint of on-press developability.

The details of each component contained in the image recording layer will be described below.

[ Polymer A containing structural units A1 having ethylenically unsaturated groups ]

The image recording layer used in the present invention contains a polymer a (hereinafter, also simply referred to as "polymer a") containing a structural unit a1 having an ethylenically unsaturated group.

The weight average molecular weight (Mw) of the polymer A is 2,500 to 35,000, preferably 2,500 to 20,000, more preferably 5,000 to 18,000, from the viewpoint of improving the brush resistance, on-press developability and UV brush resistance and suppressing the occurrence of mottled dirt.

From the viewpoint of improving the brushing resistance and the UV brushing resistance, the content of the structural unit a1 having an ethylenically unsaturated group (hereinafter, also simply referred to as "structural unit a 1") in the polymer a is 15 mol% or more, preferably 30 mol% or more, and more preferably 40 mol% or more.

The polymer a may contain 1 kind of the structural unit a1 alone, or may contain 2 or more kinds.

The content of the structural unit a 1in the polymer a is preferably 80 mol% or less, more preferably 60 mol% or less, from the viewpoint of improving on-press developability and suppressing the occurrence of mottled dirt.

In the present invention, the molar content (mol%) of the structural unit in the polymer is a value converted from the structural unit as a monomer unit. Specifically, the molar content (mol%) of a specific structural unit in a polymer means the content (%) of a specific monomer unit with respect to the content of all monomer units contained in the polymer.

Structural unit A1-

The structural unit A1 is a structural unit having an ethylenically unsaturated group. The ethylenically unsaturated group is not particularly limited, and examples thereof include a vinyl group, an allyl group, a vinylphenyl group, a (meth) acrylamide group, and a (meth) acryloyloxy group, and from the viewpoint of reactivity, a (meth) acryloyloxy group is preferable.

The structural unit a1 can be introduced by polymer reaction or copolymerization. Specifically, it can be introduced, for example, by the following method: a method of reacting an epoxy group and a compound having an ethylenically unsaturated group (e.g., glycidyl methacrylate) with a polymer having introduced therein a structural unit having a carboxyl group such as methacrylic acid, a method of reacting a compound having an isocyanate group and an ethylenically unsaturated group (e.g., 2-isocyanatoethyl methacrylate) with a polymer having introduced therein a structural unit having a group having an active hydrogen such as a hydroxyl group, or the like.

The structural element a1 can also be introduced by the following method: and reacting a compound having a carboxyl group and an ethylenically unsaturated group with a polymer having an epoxy group-containing structural unit such as glycidyl (meth) acrylate introduced therein.

The structural unit a1 can be introduced into the polymer a by using a monomer containing a partial structure represented by the following formula a1 or the following formula a2, for example. Specifically, for example, after polymerization using at least the above-mentioned monomer, an ethylenically unsaturated group is formed in a partial structure represented by the following formula a1 or the following formula a2 by an elimination reaction using an alkali compound, whereby the structural unit a1 is introduced into the polymer a.

In the formulae a1 and a2, R^aRepresents a hydrogen atom or an alkyl group, A^aRepresents a halogen atom, X^arepresents-O-or-NR^N-，R^NRepresents a hydrogen atom or an alkyl group.

In the formulae a1 and a2, R^aPreferably a hydrogen atom or a methyl group.

In the formulae a1 and a2, A^aPreferably a chlorine atom, a bromine atom or an iodine atom.

In the formulae a1 and a2, X^apreferably-O-. X^arepresents-NR^NIn the case of-R^NPreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

The structural unit A1 includes, for example, a structural unit represented by the following formula A-1.

[ chemical formula 1]

In the formula A-1, L¹Represents a single bond or a divalent linking group, L²Represents a m +1 valent linking group, X¹And X²Each independently represents-O-or-NR^N-，R^NRepresents a hydrogen atom or an alkyl group, R¹And R²Each independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 or more.

In the formula A-1, L¹Preferably a single bond. L is¹When a divalent linking group is represented, an alkylene group, an arylene group, or a divalent group represented by bonding of these groups is preferable, and an alkylene group or a phenylene group having 2 to 10 carbon atoms is preferable.

In the formula A-1, L²A group represented by any one of the following formulae A-2 to A-6 is preferable.

In the formula A-1, X¹And X²Preferably both are-O-. And, X¹And X²At least 1 of (a) represents-NR^NIn the case of-R^NPreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula A-1, R¹Preferably methyl.

In the formula A-1, m R²At least 1 of them is preferably methyl.

In the formula A-1, m is preferably an integer of 1 to 4, more preferably 1 or 2, and further preferably 1.

[ chemical formula 2]

In the formulae A-2 to A-6, L³～L⁷Represents a 2-valent linking group, L⁵And L⁶Or may be different from X in the formula A-1¹The wavy line portion represents the bonding position with X in the formula A-1²The bonding position of (2).

In the formula A-3, L³Preferably an alkylene group, an arylene group or a group represented by these bonds, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group represented by these bonds.

In the formula A-4, L⁴Preferably an alkylene group, an arylene group or a group represented by these bonds, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group represented by these bonds.

In the formula A-5, L⁵Preferably alkyleneThe arylene group or the group represented by these bonds is more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group represented by these bonds.

In the formula A-5, L⁶Preferably an alkylene group, an arylene group or a group represented by these bonds, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group represented by these bonds.

In the formula A-6, L⁷Preferably an alkylene group, an arylene group or a group represented by these bonds, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group represented by these bonds.

Specific examples of the structural unit A1 include, but are not limited to, the structural unit A1 contained in polymers P-1 to P-13, which are specific examples of the polymer A described later.

Structural unit B1-

From the viewpoint of developability, the polymer a preferably contains a structural unit B1 having a hydrophilic group (also simply referred to as "structural unit B1").

The structural unit having a hydrophilic group and an ethylenically unsaturated group is set to correspond to the structural unit a1, but not to the structural unit B1.

Examples of the hydrophilic group in the structural unit B1 include-SO₃M¹、-OH、-CN、-CONR¹R²、-NR²COR¹(M¹Represents a hydrogen atom, a metal ion, an ammonium ion or a phosphonium ion, R¹、R²Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group. R¹And R²May be bonded to form a ring. ) -NR³R⁴、-N⁺R³R⁴R⁵X^-(R³～R⁵Each independently represents an alkyl group having 1 to 8 carbon atoms, X^-Representing a counter anion), a group represented by the following formula PO, and the like.

The structural unit B1 may be a structural unit derived from an N-vinyllactam compound such as N-vinylpyrrolidone or N-vinylcaprolactam, and the residue obtained when these N-vinyllactam compounds are used in the polymerization reaction corresponds to a hydrophilic group.

Of these hydrophilic groups, -CONR is preferred¹R²Or a group represented by the formula PO, more preferably a group represented by the formula PO.

In the formula PO, L^PEach independently represents an alkylene group, R^PRepresents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 100.

In the formula PO, L^PPreferably independently of each other vinyl, 1-methylvinyl or 2-methylvinyl, more preferably vinyl.

In the formula PO, R^PPreferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, still more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

In the formula PO, n is preferably an integer of 1 to 10, more preferably an integer of 1 to 4.

From the viewpoint of improving the brushing resistance and the UV brushing resistance, the polymer a preferably contains a structural unit containing an ether bond as the structural unit B1. When the polymer a contains a sulfur atom, it is considered that the brush resistance and the UV brush resistance are easily improved by the S — O interaction between the oxygen atom and the sulfur atom in the ether bond.

Examples of the structural unit containing the ether bond include a structural unit containing a group represented by the formula PO.

The structural unit B1 is preferably a structural unit represented by the following formula B-1.

[ chemical formula 3]

In the formula B-1, X^Brepresents-O-or-NR^N-，R^NRepresents a hydrogen atom or an alkyl group, L^BRepresents a single bond or a 2-valent linking group, R^B1Represents a hydrophilic group, R^B2Represents a hydrogen atom or an alkyl group.

In the formula B-1, X^Bpreferably-O-. X^Bis-NR^NIn the case of-R^NPreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula B-1, L^BPreferably a single bond. L is^BIn the case of a 2-valent linking group, L^BPreferably an alkylene group, an arylene group or a group represented by these bonds, and preferably an alkylene group having 1 to 4 carbon atoms, a phenylene group or a group represented by these bonds.

In the formula B-1, R^B1The hydrophilic group in the structural unit B1 is preferable, and-CONR is more preferable¹R²Or a group represented by the formula PO, and more preferably a group represented by the formula PO.

In the formula B-1, R^B2Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom or a methyl group.

The polymer a may contain 1 kind of the structural unit B1 alone, or may contain 2 or more kinds.

The content of the structural unit B1 in the polymer a is preferably 0 mol% to 80 mol%, more preferably 5 mol% to 60 mol%, from the viewpoint of satisfying both the on-press developability and the ink-receptivity of the ink.

Specific examples of the structural unit B1 include, but are not limited to, the structural unit B1 contained in the polymers P-1 to P-11 and P-13, which are specific examples of the polymer A to be described later.

Structural unit C1-

From the viewpoint of ink-stainability, the polymer a preferably contains a structural unit C1 containing a hydrophobic group.

Examples of the hydrophobic group in the structural unit C1 include an alkyl group, an aryl group, and an aralkyl group.

The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a cyclohexyl group, a 2-ethylhexyl group, and a dicyclopentyl group.

The aryl group is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group.

The aralkyl group is preferably an aralkyl group having 1 to 10 carbon atoms in the alkyl group and 6 to 20 carbon atoms in the aryl group, more preferably an aralkyl group having 1 to 1 carbon atom in the alkyl group and a phenyl group in the aryl group, and still more preferably a benzyl group.

The structural unit C1 is preferably a structural unit represented by the following formula C-1 or formula C-2.

[ chemical formula 4]

In the formula C-1, X^Crepresents-O-or-NR^N-，R^NRepresents a hydrogen atom or an alkyl group, R^C1Represents a hydrophobic group, R^C2Represents a hydrogen atom or an alkyl group.

In the formula C-1, X^Cpreferably-O-. X^Cis-NR^NIn the case of-R^NPreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula C-1, R^C1The hydrophobic group in the structural unit C1 is preferably an alkyl group or an aralkyl group, and more preferably an alkyl group having 1 to 10 carbon atoms or an aralkyl group in which the alkyl group has 1 to 10 carbon atoms and the aryl group is a phenyl group.

In the formula C-1, R^C2Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom or a methyl group.

In the formula C-2, R^C3Represents a monovalent substituent, R^C4Represents a hydrogen atom or an alkyl group, and n represents an integer of 0 to 5.

In the formula C-2, R^C3The alkyl group, the aryl group or the aralkyl group is preferable, and the alkyl group having 1 to 10 carbon atoms, the aryl group having 6 to 20 carbon atoms or the aralkyl group having 7 to 21 carbon atoms is more preferable.

In the formula C-2, R^C4Preferably a hydrogen atom or a methyl group.

In the formula C-2, n is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, further preferably 0 or 1, and particularly preferably 0.

The polymer a may contain 1 kind of the structural unit C1 alone, or may contain 2 or more kinds.

The content of the structural unit C1 in the polymer a is preferably 1 to 80 mol%, more preferably 3 to 40 mol%, from the viewpoint of satisfying both the on-press developability and the ink-receptivity of the ink.

Specific examples of the structural unit C1 include, but are not limited to, the structural unit C1 contained in polymers P-1 to P-13, which are specific examples of the polymer A to be described later.

Structural units derived from polyfunctional thiol compounds

The polymer a is preferably a star-shaped polymer containing a structural unit derived from a polyfunctional thiol compound having 3 or more functions and 10 or less functions.

To prepare a star-shaped polymer, the polymer a preferably has only 1 structural unit derived from a polyfunctional thiol compound having 3 or more functions and 10 or less functions.

When the polymer A is a star polymer, it is preferably an n-star polymer (n-star copolymer) and n is an integer of 3 to 10.

The polymer A can be ordered star polymer (regular star polymer) or mixed chain star polymer (variegated star polymer).

The star polymer can be produced by a known method such as a method of copolymerizing a monomer constituting the structural unit a1, a monomer constituting the structural unit B1, and a monomer constituting the structural unit C1 in the presence of a polyfunctional thiol compound having a functionality of 3 to 10, for example. As details of the method for producing the star polymer and the polyfunctional thiol compound, reference can be made to the description of Japanese patent laid-open publication No. 2012-148555.

The star polymer as the polymer A in the present invention is different from the star polymer described in Japanese patent laid-open No. 2012-148555 in weight average molecular weight and content of the structural unit A1. The weight-average molecular weight and the content of the structural unit a1 can be controlled by adjusting the amount of the polyfunctional thiol compound used, the amount of the polymerization initiator used in copolymerizing the monomers, and the like in the method for producing a star polymer described in jp 2012-148555 a, for example.

The polyfunctional thiol compound having 3 to 10 functions used in the present invention is not particularly limited, but is preferably a polyfunctional thiol compound having 3 to 8 functions, and more preferably a polyfunctional thiol compound having 3 to 6 functions.

The polyfunctional thiol compound having 3 or more and 10 or less functions used in the present invention is preferably a compound represented by the following formula S-1.

[ chemical formula 5]

In the formula S-1, L^SRepresents an ns-valent hydrocarbon group which may contain an ether bond, R^SRepresents a 1-valent hydrocarbon group having a thiol group as a substituent, and ns represents an integer of 3 to 10.

In the formula S-1, L^SThe n-valent aliphatic hydrocarbon group which may contain an ether bond is preferable, and the n-valent unsaturated aliphatic hydrocarbon group which may contain an ether bond is more preferable.

As L^SSpecific examples of the compound include, but are not limited to, compounds obtained by removing all hydroxyl groups contained in the compound from a polyol compound such as pentaerythritol, dipentaerythritol, sorbitol, mannitol, iditol, dulcitol, and inositol.

In the formula S-1, R^SThe aliphatic hydrocarbon group having a valence of 1 with a thiol group as a substituent is preferable, and the unsaturated aliphatic hydrocarbon group having a valence of 1 with a thiol group as a substituent is more preferable.

As R^SSpecific examples thereof include, but are not limited to, mercaptomethyl, 2-mercaptoethyl, and 2-mercaptopropyl.

In the formula S-1, ns represents an integer of 3 to 10, preferably an integer of 3 to 8, and more preferably an integer of 3 to 6.

Further, as the polyfunctional thiol compound, compounds a to F described in japanese patent laid-open publication No. 2012-148555 can also be preferably used.

Other structural units-

The polymer a of the present invention may further contain other structural units.

Examples of the other structural unit include a structural unit derived from a monofunctional thiol compound, a structural unit derived from a 2-functional thiol compound, and the like.

Sulfur content-

From the viewpoint of improving the brushing resistance and the UV brushing resistance, the content of the sulfur element is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, based on the total mass of the polymer a.

It is considered that the content of sulfur element is in the above range and the brushing resistance and the UV brushing resistance are easily improved by the influence of the S — O interaction.

The sulfur element is introduced into the polymer a as an element contained in a structural unit derived from the above monofunctional thiol compound or 2 functional thiol compound, or an element contained in a structural unit derived from a polyfunctional thiol compound having 3 or more functions and 10 or less functions, which will be described later.

Specific examples of the polymer a are shown in the following table, but the polymer a used in the present invention is not limited thereto.

[ Table 1]

In the tables, the mol% in each column of the structural unit a1 to the structural unit C1 indicates the content (mol%) of each structural unit in the polymer a. For example, in P-1, the content of the structural unit A1 was 25 mol%, the content of the structural unit B1 was 55 mol%, the content of the structural unit C1 was 16 mol%, and the content of the structural unit SH1 derived from the polyfunctional thiol compound was 4 mol%.

The phrase "33 (5: 5)" in the column of mol% of the structural unit C1 in the polymer P-11 means that 2 structural units C-1 are contained at a molar ratio of 5:5, and the total content thereof is 33 mol%.

Details of SH1 to SH5 as structural units derived from a polyfunctional thiol compound in the following table are shown.

[ chemical formula 6]

The polymer P-1 is a polymer A containing a structural unit derived from a monofunctional thiol compound SH1, and is a compound in which a molecular chain formed from a structural unit A1 to a structural unit C1 is bonded to SH1 via a thioether bond derived from a thiol bond in SH 1.

The polymer P-2 is a polymer a containing a structural unit derived from a 2-functional thiol compound SH2, and is a compound in which a molecular chain formed from a structural unit a1 to a structural unit C1 is bonded to SH2 via thioether bonds derived from thiol bonds in SH2, respectively. That is, it is considered that the polymer P-2 has 2 thioether bonds.

The polymer P-3 is a polymer A comprising a structural unit derived from a 4-functional thiol compound SH3, and is a compound in which a molecular chain formed from the structural unit A1 to the structural unit C1 is bonded to SH3 via thioether bonds derived from thiol bonds in SH3, respectively. That is, it is considered that the polymer P-3 has 4 thioether bonds.

The polymer P-4 is a polymer a containing a structural unit derived from a 4-functional thiol compound SH4, and is a compound in which a molecular chain formed from a structural unit a1 to a structural unit C1 is bonded to SH4 via thioether bonds derived from thiol bonds in SH4, respectively. That is, it is considered that the polymer P-4 has 4 thioether bonds.

The polymers P-5 to P-12 are a polymer A comprising a structural unit derived from a 6-functional thiol compound SH5, and are compounds in which a molecular chain formed from a structural unit A1 to a structural unit C1 is bonded to SH5 via a thioether bond derived from a thiol bond in SH5, respectively. That is, it is considered that the polymer P-5 has 6 thioether bonds.

The image recording layer may contain 1 polymer a alone or 2 or more polymers at the same time.

The content of the polymer a with respect to the total mass of the image recording layer is preferably 5 mass% or more and 95 mass% or less, more preferably 7 mass% or more and 60 mass% or less, and more preferably 10 mass% or more and 30 mass% or less.

[ Electron acceptor type polymerization initiator ]

The image recording layer preferably contains an electron acceptor type polymerization initiator.

The electron acceptor type polymerization initiator used in the present invention is a compound which generates a polymerization initiating species such as a radical or a cation by light, heat or energy of both, and a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, or the like can be appropriately selected and used.

As the electron acceptor type polymerization initiator, a radical polymerization initiator is preferable, and an onium salt compound is more preferable.

The electron acceptor type polymerization initiator is preferably an infrared ray-sensitive polymerization initiator.

The electron acceptor type polymerization initiator may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Examples of the radical polymerization initiator include (a) an organic halide, (b) a carbonyl compound, (c) an azo compound, (d) an organic peroxide, (e) a metallocene compound, (f) an azide compound, (g) a hexaarylbisimidazole compound, (i) a disulfone compound, (j) an oxime ester compound, and (k) an onium salt compound.

(a) As the organic halide, for example, compounds described in paragraphs 0022 to 0023 of Japanese patent laid-open No. 2008-195018 are preferable.

(b) As the carbonyl compound, for example, a compound described in paragraph 0024 of Japanese patent laid-open No. 2008-195018 is preferable.

(c) As the azo compound, for example, an azo compound described in Japanese patent application laid-open No. 8-108621 can be used.

(d) As the organic peroxide, for example, a compound described in paragraph 0025 of Japanese patent laid-open No. 2008-195018 is preferable.

(e) As the metallocene compound, for example, the compounds described in paragraph 0026 of Japanese patent laid-open No. 2008-195018 are preferable.

(f) Examples of the azide compound include compounds such as 2, 6-bis (4-azidobenzylidene) -4-methylcyclohexanone.

(g) As the hexaarylbisimidazole compound, for example, the compound described in paragraph 0027 of Japanese patent laid-open No. 2008-195018 is preferable.

(i) Examples of the disulfone compound include those described in Japanese patent application laid-open Nos. 61-166544 and 2002-328465.

(j) As the oxime ester compound, for example, compounds described in paragraphs 0028 to 0030 of Japanese patent laid-open No. 2008-195018 are preferable.

Preferable compounds among the above-mentioned electron acceptor type polymerization initiators include oxime ester compounds and onium salt compounds from the viewpoint of curability. Among these, from the viewpoint of brush resistance, an iodonium salt compound, a sulfonium salt compound, or an oxazinium salt compound is preferable, an iodonium salt compound or a sulfonium salt compound is more preferable, and an iodonium salt compound is particularly preferable.

Specific examples of these compounds are shown below, but the present invention is not limited thereto.

As examples of the iodonium salt compound, a diaryliodonium salt compound is preferable, a diphenyliodonium salt compound in which an electron donating group, for example, an alkyl group or an alkoxy group is particularly preferable, and an asymmetric diphenyliodonium salt compound is preferable. Specific examples thereof include diphenyliodonium hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2, 4-diethoxyphenyliodonium tetrafluoroborate, 4-octyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium hexafluorophosphate, bis (4-tert-butylphenyl) iodonium tetraphenylborate.

As an example of the sulfonium salt compound, a triarylsulfonium salt compound is preferable, particularly a triarylsulfonium salt compound in which at least a part of groups on an electron-withdrawing group, for example, an aromatic ring is substituted with a halogen atom is preferable, and a triarylsulfonium salt compound in which the total number of substitution of halogen atoms on an aromatic ring is 4 or more is more preferable. Specific examples thereof include triphenylsulfonium hexafluorophosphate, triphenylsulfonium benzoylformate, bis (4-chlorophenyl) phenylsulfinium benzoylformate, bis (4-chlorophenyl) -4-methylphenylsulfonium tetrafluoroborate, tris (4-chlorophenyl) sulfonium 3, 5-bis (methoxycarbonyl) benzenesulfonate, tris (4-chlorophenyl) sulfonium hexafluorophosphate, and tris (2, 4-dichlorophenyl) sulfonium hexafluorophosphate.

The counter anion of the iodonium salt compound and the sulfonium salt compound is preferably a sulfonamide anion or a sulfonimide anion, and more preferably a sulfonimide anion.

As sulfonamide anions, arylsulfonamide anions are preferred.

Also, as the sulfonimide anion, a bisarylsulfonimide anion is preferable.

Specific examples of the sulfonamide anion or the sulfonimide anion will be described below, but the present invention is not limited to these. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[ chemical formula 7]

The content of the electron acceptor type polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass, with respect to the total mass of the image recording layer.

[ polymerizable Compound ]

The image recording layer in the present invention preferably contains a polymerizable compound.

In the present invention, the polymer a may be a polymerizable compound, and the compound belonging to the polymer a is not a polymerizable compound.

The molecular weight (weight average molecular weight when having a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 2,500, and more preferably 50 or more and 2,000 or less.

The polymerizable compound used in the present invention may be, for example, a radical polymerizable compound or a cationic polymerizable compound, but is preferably an addition polymerizable compound (ethylenically unsaturated compound) having at least 1 ethylenically unsaturated bond. As the ethylenically unsaturated compound, a compound having at least 1 terminal ethylenically unsaturated bond is preferable, and a compound having 2 or more terminal ethylenically unsaturated bonds is more preferable. The polymerizable compound has a chemical form such as a monomer, a prepolymer, a dimer, a 3-mer, an oligomer, or a mixture thereof.

Examples of the monomer include an unsaturated carboxylic acid (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.) and esters and amides thereof, and esters of an unsaturated carboxylic acid and a polyol compound and amides of an unsaturated carboxylic acid and a polyamine compound are preferably used. Further, it is also preferably used for addition reaction products of unsaturated carboxylic acid esters or amides having nucleophilic substituents such as hydroxyl group, amino group, mercapto group, etc. with monofunctional or polyfunctional isocyanates or epoxies, dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids, and the like. Also, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituent groups such as isocyanate group and epoxy group with monofunctional or polyfunctional alcohols, amines and thiols, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituent groups such as halogen atom and p-toluenesulfonyloxy group with monofunctional or polyfunctional alcohols, amines and thiols are also preferable. As a different example, a compound group in which the unsaturated carboxylic acid is replaced with an unsaturated phosphonic acid, styrene, vinyl ether, or the like can also be used. These are described in Japanese patent laid-open Nos. 2006-508380, 2002-287344, 2008-256850, 2001-342222, 9-179296, 9-179297, 9-179298, 2004-294935, 2006-243493, 2002-275129, 2003-064130, 2003-280187, and 10-333321.

Specific examples of the ester monomer of the polyol compound and the unsaturated carboxylic acid include ethylene glycol diacrylate, 1, 3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, ethylene oxide isocyanurate (EO) -modified triacrylate, and polyester acrylate oligomer. Examples of the methacrylate include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis [ p- (3-methacryloyloxy-2-hydroxypropoxy) phenyl ] dimethyl methane, and bis [ p- (methacryloyloxyethoxy) phenyl ] dimethyl methane. Specific examples of the amide monomer of the polyamine compound and the unsaturated carboxylic acid include methylene bisacrylamide, methylene bismethacrylamide, 1, 6-hexamethylene bisacrylamide, 1, 6-hexamethylene bismethacrylamide, diethylenetriamine triacrylate, xylylene bisacrylamide, and xylylene bismethacrylamide.

Further, a urethane addition polymerizable compound produced by an addition reaction of an isocyanate and a hydroxyl group is also preferably used, and specific examples thereof include a vinyl urethane compound containing 2 or more polymerizable vinyl groups in 1 molecule of a vinyl monomer containing a hydroxyl group represented by the following formula (M) added to a polyisocyanate compound having 2 or more isocyanate groups in 1 molecule described in japanese patent publication No. 48-041708, and the like.

CH₂＝C(R^M4)COOCH₂CH(R^M5)OH (M)

In the formula (M), R^M4And R^M5Each independently represents a hydrogen atom or a methyl group.

Further, the urethane acrylates described in Japanese patent laid-open Nos. 51-037193, 2-032293, 2-016765, 2003-344997 and 2006-065210, 58-049860, 56-017654 and 62-039417, urethane compounds having an ethylene oxide skeleton as described in Japanese patent publication No. 62-039418, Japanese patent publication No. 2000-250211 and Japanese patent publication No. 2007-094138, and urethane compounds having a hydrophilic group as described in U.S. Pat. No. 7153632, Japanese patent application No. 8-505958, Japanese patent publication No. 2007-coza293221 and Japanese patent publication No. 2007-coza293223.

The details of the structure of the polymerizable compound, the methods of use such as single use, simultaneous use, or addition amount can be arbitrarily set.

The content of the polymerizable compound is preferably 5 to 75% by mass, more preferably 10 to 70% by mass, and particularly preferably 15 to 60% by mass, based on the total mass of the image recording layer.

[ Infrared absorber ]

The image recording layer preferably contains an infrared absorber.

Examples of the infrared absorber include pigments and dyes.

As the dye used as the infrared absorber, there can be used a commercially available dye and a known dye described in the literature such as "the dye review" (edited by the society of organic synthetic chemistry, showa, 45 years). Specific examples thereof include azo dyes, metal-complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes, cyanine dyes, squarylium pigments, pyrylium salts, metal thiolate complexes, and the like.

Among these dyes, particularly preferred dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiol complexes, and indolenine cyanine dyes. Further, cyanine dye or indolenine cyanine dye may be mentioned. Among them, cyanine is particularly preferable.

Specific examples of the cyanine dye include compounds described in paragraphs 0017 to 0019 of Japanese patent application laid-open No. 2001-133969, paragraphs 0016 to 0021 of Japanese patent application laid-open No. 2002-023360, and paragraphs 0012 to 0037 of Japanese patent application laid-open No. 2002-040638, preferably include compounds described in paragraphs 0034 to 0041 of Japanese patent application laid-open No. 2002-278057, and paragraphs 0080 to 0086 of Japanese patent application laid-open No. 2008-195018, and particularly preferably include compounds described in paragraphs 0035 to 0043 of Japanese patent application laid-open No. 2007-090850, and compounds described in paragraphs 0105 to 0113 of Japanese patent application laid-open No. 2012-206495.

Further, the compounds described in paragraphs 0008 to 0009 of Japanese patent application laid-open No. 5-005005 and paragraphs 0022 to 0025 of Japanese patent application laid-open No. 2001-222101 can also be preferably used.

As the pigment, the compounds described in paragraphs 0072 to 0076 of Japanese patent application laid-open No. 2008-195018 are preferred.

Only 1 kind of infrared absorber may be used, or 2 or more kinds may be used simultaneously. Further, as the infrared absorber, a pigment and a dye may be used together.

The content of the infrared absorber in the image recording layer is preferably 0.1 to 10.0 mass%, more preferably 0.5 to 5.0 mass%, with respect to the total mass of the image recording layer.

[ acid developer ]

The image recording layer used in the present invention preferably contains an acid developer.

The "acid developer" used in the present invention is a compound having a property of developing color by heating in a state of receiving an electron-accepting compound (for example, a proton such as an acid). The acid color developer is particularly preferably a colorless compound having a partial skeleton such as a lactone, a lactam, a sultone, a spiropyran, an ester, or an amide, and the partial skeleton is rapidly opened or cleaved when it is brought into contact with an electron-accepting compound.

Examples of such an acid developer include 3, 3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (referred to as "crystal violet lactone"), 3-bis (4-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1, 2-dimethylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3-bis (1, 2-dimethylindol-3-yl) -5-dimethylaminophthalide, and, 3, 3-bis (1, 2-dimethylindol-3-yl) -6-dimethylaminobenzphthalide, 3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminobenzphthalide, 3-bis (2-phenylindol-3-yl) -6-dimethylaminobenzphthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-3-yl) -6-dimethylaminobenzphthalide,

3, 3-bis [1, 1-bis (4-dimethylaminophenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3-bis [1, 1-bis (4-pyrrolidinophenyl) ethen-2-yl ] -4,5,6, 7-tetrabromophthalide, 3-bis [1- (4-dimethylaminophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3-bis [1- (4-pyrrolidinophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3- [1, 1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-diethylaminophenyl) phthalide, 3- [1, 1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-N-ethyl-N-phenylaminophenyl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-N-octyl-2-methylindol-3-yl) -phthalide, 3-bis (1-N-octyl-2-methylindol-3-yl) -phthalide, 3- (2-methyl-4-diethylaminophenyl) -3- (1-N-octylamino) Phthalides such as phenyl-2-methylindol-3-yl-phthalide,

4, 4-bis-dimethylaminobenzopropanol benzyl ether, N-halophenyl-leuco auramine, N-2,4, 5-trichlorophenyl leuco auramine, rhodamine-B-anilino lactam, rhodamine- (4-nitroanilino) lactam, rhodamine-B- (4-chloroanilino) lactam, 3, 7-bis (diethylamino) -10-benzoylbenzoxazine, benzoyl leuco methylene blue, 4-nitrobenzoyl methylene blue,

3, 6-dimethoxyfluorane, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6, 7-dimethylfluorane, 3-N-hexyl-N-N-butylamino-7-methylfluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-di-N-hexylaminofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-methoxyfluorane, and mixtures thereof, 3-diethylamino-7- (2 ' -fluoroanilino) fluoran, 3-diethylamino-7- (2 ' -chloroanilino) fluoran, 3-diethylamino-7- (3 ' -chloroanilino) fluoran, 3-diethylamino-7- (2 ', 3 ' -dichloroanilino) fluoran, 3-diethylamino-7- (3 ' -trifluoromethylanilino) fluoran, 3-di-N-butylamino-7- (2 ' -fluoroanilino) fluoran, 3-di-N-butylamino-7- (2 ' -chloroanilino) fluoran, 3-N-isopentyl-N-ethylamino-7- (2 ' -chloroanilino) fluoran, and a salt thereof,

3-N-N-hexyl-N-ethylamino-7- (2' -chloroanilino) fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-N-butylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-methoxy-7-anilinofluoran, 3-di-N-butylamino-6-ethoxy-7-anilinofluoran, 3-pyrrolo-6-methyl-7-anilinofluoran, 3-hydropyridyl-6-methyl-7-anilinofluoran, 3-morpholinyl-6-methyl-7-anilinofluoran, 2-diethylamino-6-chloro-7-anilinofluoran, 3-di-N-butylamino-6-ethoxy-7-anilinofluoran, 3-hydropyrido-6-methyl-7, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-N-butylamino-6-methyl-7-anilinofluoran, 3-di-N-pentylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-N-propyl-N-ethylamino-6-methyl-7-anilinofluoran, and mixtures thereof, 3-N-N-butyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-N-butyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-N-hexyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-propylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-butyl-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-hexylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-octylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-octylamino-6-methyl-7-anilinofluoran,

3-N- (2 '-methoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (2' -methoxyethyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2 '-methoxyethyl) -N-isobutylamino-6-methyl-7-anilinofluoran, 3-N- (2' -ethoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (2 '-ethoxyethyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3' -methoxypropyl) -N-methylamino-6-anilinofluoran -methyl-7-anilinofluoran, 3-N- (3 ' -methoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3 ' -ethoxypropyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (3 ' -ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2 ' -tetrahydrofurfuryl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (4 ' -tolyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-ethyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (3 ' -methylanilino) fluoran, 3-diethylamino-6-methyl-7- (2 ', 6 ' -dimethylanilino) fluoran, 3-di-N-butylamino-7- (2 ', 6 ' -dimethylanilino) fluoran, 2-bis [4 ' - (3-N-cyclohexyl-N-methylamino-6-methylfluoran) -7-ylaminophenyl ] propane, 3- [4 ' - (4-anilinophenyl) aminophenyl ] amino-6-methylaminophenyl ] propane Fluoranes such as 7-chlorofluorane, 3- [ 4' - (dimethylaminophenyl) ] amino-5, 7-difluorane, and the like,

3- (2-methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-n-propoxycarbonylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-n-octyl-2-methylindol-3-yl) -4, 7-diaza-phthalide, 3-bis (2-ethoxy-4-diethylaminophenyl) -4-aza-phthalide, 3-bis (1-n-octyl-2-methylindol-3-yl) -4-aza-phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-aza-phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) -4 or 7-aza-phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-aza-phthalide Indo-3-yl) -4 or 7-azaphthalide, 3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide, 3- (2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide 3-methyl-spiro-dinaphthopyran, Phthalides such as 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran-3, 6-bis (dimethylamino) fluorene-9-spiro-3 '- (6' -dimethylamino) phthalide, and 3, 6-bis (diethylamino) fluorene-9-spiro-3 '- (6' -dimethylamino) phthalide, and the like,

Further, 2 ' -anilino-6 ' - (N-ethyl-N-isoamyl) amino-3 ' -methylspiro [ isobenzofuran-1 (3H),9 ' - (9H) xanthene ] -3-one, 2 ' -anilino-6 ' - (N-ethyl-N- (4-tolyl)) amino-3 ' -methylspiro [ isobenzofuran-1 (3H),9 ' - (9H) xanthene ] -3-one, 3 ' -N, N-dibenzylamino-6 ' -N, N-diethylaminospiro [ isobenzofuran-1 (3H),9 ' - (9H) xanthene ] -3-one, 2 ' - (N-methyl-N-phenyl) amino-6 ' - (N-ethyl-N- (4-tolyl)) aminospiro [ isobenzofuran-1 (3H), 9' - (9H) xanthen ] -3-one, and the like.

Among them, the acid color developer used in the present invention is preferably at least 1 compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds and spirolactam compounds, from the viewpoint of color developability.

The hue of the coloring matter after color development is preferably green, blue or black from the viewpoint of visibility.

As the acid-color developer, commercially available products such as ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, H-2114 (Fukui Yamada Chemical Co., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, TH-107 (HODOGAYA CHEMICAL CO., LTD. manufactured.), ODB-2, ODB-4, ODB-250, ODB-BlXV, BLUE-63, 169, GN-2, GN-118, Yard-40, and crystal violet (Red Co., manufactured by Tokyo Chemical Co., Ltd.), and so on. Among these commercially available products, the films formed from ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63, GN-169, and crystal violet lactone are preferable because they have good visible light absorption.

These acid color developers may be used alone in 1 kind, or may be used in combination with 2 or more kinds of components.

The content of the acid developer is preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass, based on the total mass of the image recording layer.

[ Polymer particles ]

The image recording layer preferably contains polymer particles.

The polymer particles are preferably selected from the group consisting of thermoplastic polymer particles, thermally reactive polymer particles, polymer particles having a polymerizable group, microcapsules containing a hydrophobic compound, and microgels (crosslinked polymer particles). Among them, polymer particles or microgels having a polymerizable group are preferable. In a particularly preferred embodiment, the polymer particles comprise at least 1 ethylenically unsaturated polymerizable group. The presence of such polymer particles can provide an effect of improving the brush resistance of exposed portions and the on-press developability of unexposed portions.

Also, the polymer particles are preferably thermoplastic polymer particles.

As the thermoplastic polymer particles, thermoplastic polymer particles described in, for example, Research Disclosure No.33303, Japanese patent application laid-open No. 9-123387, Japanese patent application laid-open No. 9-131850, Japanese patent application laid-open No. 9-171249, Japanese patent application laid-open No. 9-171250 and European patent application No. 931647, which are published in 1992, are preferable.

Specific examples of the polymer constituting the thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and an acrylate or methacrylate having a polyalkylene structure, or mixtures thereof. Preferably, the polymer is a copolymer containing polystyrene, styrene and acrylonitrile, or polymethyl methacrylate. The thermoplastic polymer particles preferably have an average particle diameter of 0.01 to 3.0. mu.m.

Examples of the thermally reactive polymer particles include polymer particles having a thermally reactive group. The thermally reactive polymer particles form a hydrophobic region by crosslinking based on a thermal reaction and a functional group change at this time.

The thermally reactive group in the polymer particles having a thermally reactive group may be a functional group which can form a chemical bond and which can undergo any reaction, and is preferably a polymerizable group, and examples thereof include an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) which undergoes a free polymerization reaction, a cationically polymerizable group (for example, vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), an isocyanate group or a block thereof which undergoes an addition reaction, an epoxy group, a vinyloxy group, a functional group having an active hydrogen atom (for example, amino group, hydroxyl group, carboxyl group, etc.) which is a reaction target of these groups, a carboxyl group which undergoes a condensation reaction, a hydroxyl group or an amino group which is a reaction target, an acid anhydride which undergoes a ring-opening addition reaction, an amino group or a hydroxyl group which is a reaction target, and the like.

As described in, for example, japanese patent application laid-open nos. 2001-277740 and 2001-277742, microcapsules contain at least a part of the components of the image recording layer. The constituent components of the image recording layer may be contained outside the microcapsules. A preferable embodiment of the microcapsule-containing image recording layer has a structure in which a hydrophobic constituent is contained in the microcapsule and a hydrophilic constituent is contained outside the microcapsule.

The microgel (crosslinked polymer particles) may contain a part of the constituent components of the image recording layer on at least one of the surface and the inside thereof. In particular, from the viewpoint of image forming sensitivity and brushing resistance, a reactive microgel having a free polymerizable group on the surface thereof is preferred.

When the constituent components of the image recording layer are microencapsulated or microgeled, a known method can be applied.

The polymer particles are preferably obtained by reacting a polyvalent phenol compound having 2 or more hydroxyl groups in the molecule, a polyvalent isocyanate compound which is an adduct of isophorone diisocyanate, and a compound having active hydrogen, from the viewpoint of brushing resistance, stain resistance, and storage stability.

The polyhydric phenol compound is preferably a compound having a plurality of benzene rings having a phenolic hydroxyl group.

The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and still more preferably at least one compound selected from the group consisting of propylene glycol, glycerin, and trimethylolpropane.

The particles of the resin obtained by the reaction of the polyvalent isocyanate compound which is an adduct of a polyvalent phenol compound having 2 or more hydroxyl groups in the molecule with isophorone diisocyanate and the compound having active hydrogen are preferably polymer particles described in paragraphs 0032 to 0095 in Japanese patent laid-open No. 2012-206495.

In addition, from the viewpoint of brush resistance and solvent resistance, the polymer particles preferably have a hydrophobic main chain, and include both i) a constituent unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a side group including a hydrophilic polyalkylene oxide segment.

The hydrophobic main chain is preferably an acrylic resin chain.

Preferable examples of the cyano side group include- [ CH ]₂CH(C≡N)-]Or- [ CH ]₂C(CH₃)(C≡N)-]。

Further, the constituent unit having the above cyano side group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or from a combination of these.

The alkylene oxide in the hydrophilic polyalkylene oxide segment is preferably ethylene oxide or propylene oxide, and more preferably ethylene oxide.

The number of repetition of the alkylene oxide structure in the hydrophilic polyalkylene oxide segment is preferably 10 to 100, more preferably 25 to 75, and still more preferably 40 to 50.

The particles having a hydrophobic main chain and containing both i) a constitutional unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constitutional unit having a side group containing a hydrophilic polyalkylene oxide segment are preferably particles described in paragraphs 0039 to 0068 of Japanese patent application laid-open No. 2008-503365.

The average particle diameter of the polymer particles is preferably 0.01 to 3.0. mu.m, more preferably 0.03 to 2.0. mu.m, and still more preferably 0.10 to 1.0. mu.m. Within this range, good resolution and stability over time can be obtained.

The average primary particle diameter of each of the particles in the present invention is as follows: an electron micrograph of the particles was measured or taken by a light scattering method and the particle diameter of 5,000 particles in total on the photograph was measured, and the average value was calculated. In addition, regarding the non-spherical particles, the particle diameter value of spherical particles having the same particle area as the particle area on the photograph is defined as the particle diameter.

The average particle size in the present invention is a volume average particle size unless otherwise specified.

The content of the polymer particles is preferably 5 to 90 mass% with respect to the total mass of the image recording layer.

[ electron donating polymerization initiator ]

The image recording layer used in the present invention preferably contains a donor-type polymerization initiator. The electron-donating polymerization initiator contributes to the improvement of the brush resistance in the lithographic printing plate. Examples of the electron donor type polymerization initiator include the following 5 types.

(i) Alkyl or arylate complexes: it is believed that the oxidized carbon-heterobonds are cleaved to generate reactive radicals. Specifically, a borate compound and the like can be given.

(ii) Aminoethoxy compound: it is believed that the reactive radicals are generated by the cleavage of the C-X bond on the carbon adjacent to the nitrogen by oxidation. As X, a hydrogen atom, a carboxyl group, a trimethylsilyl group or a benzyl group is preferable. Specific examples thereof include N-phenylglycine (which may have a substituent on the phenyl group), N-phenyliminodiacetic acid (which may have a substituent on the phenyl group), and the like.

(iii) A sulfur-containing compound: the compound obtained by substituting the nitrogen atom and the sulfur atom of the aminoethoxy compound can generate an active radical by the same action. Specifically, there may be mentioned phenylthioacetic acid (which may have a substituent on the phenyl group), and the like.

(iv) A tin-containing compound: the compound obtained by substituting the nitrogen atom and the tin atom of the aminoethoxy compound can generate a reactive radical by the same action.

(v) Sulfinates: capable of generating active radicals by oxidation. Specifically, sodium arylene sulfonate and the like can be mentioned.

Of these electron-donating polymerization initiators, the image recording layer preferably contains a borate compound. The borate compound is preferably a tetraarylborate compound or a monoalkyltriarylborate compound, and from the viewpoint of stability of the compound, a tetraarylborate compound is more preferable, and a tetraphenylborate compound is particularly preferable.

The counter cation of the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion or a tetrabutylammonium ion.

Specific examples of the borate compound include sodium tetraphenylborate.

Although B-1 to B-9 are shown below as preferred specific examples of the electron donor type polymerization initiator, it is not to be construed that the initiator is limited thereto. In the following chemical formula, Ph represents a phenyl group, and Bu represents an n-butyl group.

[ chemical formula 8]

The electron donor type polymerization initiator may be added in only 1 kind, or 2 or more kinds may be used simultaneously.

The content of the electron donor type polymerization initiator is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and still more preferably 0.1 to 20% by mass, based on the total mass of the image recording layer.

[ adhesive Polymer ]

The image recording layer may contain a binder polymer other than the polymer a.

The polymer corresponding to the above polymer a does not correspond to the binder polymer. That is, the binder polymer according to the present invention is a polymer satisfying 1 or 2 of the conditions described in the following (1) and (2).

(1) A weight average molecular weight of greater than 35,000

(2) The content of structural units A1 containing ethylenically unsaturated groups is less than 15 mol%

As the binder polymer, a (meth) acrylic resin, a polyvinyl acetal resin, or a polyurethane resin is preferable.

Among them, known binder polymers used in the image-recording layer of the lithographic printing plate precursor can be preferably used. As an example, a binder polymer used for an on-press development type lithographic printing plate precursor (hereinafter, also referred to as an on-press development binder polymer) is described in detail.

As the binder polymer for on-press development, a binder polymer having an alkylene oxide chain is preferable. The adhesive polymer having an alkylene oxide chain may have a poly (alkylene oxide) site on the main chain, and may also have a poly (alkylene oxide) site on the side chain. The graft polymer may have a poly (alkylene oxide) in a side chain, or may be a block copolymer of a block comprising a poly (alkylene oxide) containing structural unit and a block comprising a structural unit not containing a poly (alkylene oxide).

In the case of having a poly (alkylene oxide) site on the main chain, a polyurethane resin is preferred. Examples of the polymer of the main chain in the case where the polymer has a poly (alkylene oxide) moiety in a side chain thereof include a (meth) acrylic resin, a polyvinyl acetal resin, a polyurethane resin, a polyurea resin, a polyimide resin, a polyamide resin, an epoxy resin, a polystyrene resin, a novolac-type phenol resin, a polyester resin, a synthetic rubber, and a natural rubber, and a (meth) acrylic resin is particularly preferable.

Another preferable example of the binder polymer is a polymer compound (hereinafter, also referred to as a star polymer compound) having a core of a multifunctional thiol having 6 to 10 functions and bonded to the core via a thioether bond, and the polymer chain having a polymerizable group. As the star polymer compound, for example, the compounds described in Japanese patent laid-open No. 2012-148555 can be preferably used.

The star polymer compound includes a compound having a polymerizable group such as an ethylenically unsaturated bond for improving the strength of a coating film on an image portion, as described in jp 2008-195018 a, in a main chain or a side chain, preferably in a side chain. Crosslinking is formed between polymer molecules by the polymerizable group, and curing is promoted.

The polymerizable group is preferably an ethylenically unsaturated group such as a (meth) acrylic group, a vinyl group, an allyl group, or a styryl group, or an epoxy group, and from the viewpoint of polymerization reactivity, a (meth) acrylic group, a vinyl group, or a styryl group is more preferable, and a (meth) acrylic group is particularly preferable. These groups can be introduced into the polymer by a high molecular reaction or copolymerization. For example, a reaction of a polymer having a carboxyl group in a side chain thereof with glycidyl methacrylate or a reaction of a polymer having an epoxy group with an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used. These groups may be used simultaneously.

The molecular weight of the binder polymer is preferably a weight average molecular weight (Mw) of 2,000 or more, more preferably 5,000 or more, and even more preferably 10,000 to 300,000, in terms of polystyrene by GPC.

If necessary, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in Japanese patent application laid-open No. 2008-195018 can be used in combination. Further, the lipophilic polymer and the hydrophilic polymer can be used together.

In the image recording layer used in the present invention, 1 kind of binder polymer may be used alone, or 2 or more kinds may be used simultaneously.

The binder polymer may be contained in any amount in the image recording layer, but the content of the binder polymer is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, with respect to the total mass of the image recording layer.

The content of the binder polymer relative to the total mass of the polymer a and the binder polymer in the image recording layer in the present invention is preferably 0 to 99 mass%, more preferably 20 to 95 mass%, and still more preferably 40 to 90 mass%.

[ chain transfer agent ]

The image recording layer used in the present invention may contain a chain transfer agent. The chain transfer agent helps to improve the brush resistance in lithographic printing plates.

The chain transfer agent is preferably a thiol compound, more preferably a thiol compound having 7 or more carbon atoms, and still more preferably a compound having a mercapto group on an aromatic ring (aromatic thiol compound), from the viewpoint of a boiling point (difficult volatilization). The thiol compound is preferably a monofunctional thiol compound.

Specific examples of the chain transfer agent include the following compounds.

[ chemical formula 9]

[ chemical formula 10]

[ chemical formula 11]

[ chemical formula 12]

The chain transfer agent may be added in 1 kind alone, or may be used in combination of 2 or more kinds.

The content of the chain transfer agent is preferably 0.01 to 50% by mass, more preferably 0.05 to 40% by mass, and still more preferably 0.1 to 30% by mass, based on the total mass of the image recording layer.

[ Low molecular hydrophilic Compound ]

The image recording layer may contain a low-molecular hydrophilic compound in order to improve on-press developability while suppressing a decrease in the brush resistance. The low-molecular hydrophilic compound is preferably a compound having a molecular weight of less than 1,000, more preferably a compound having a molecular weight of less than 800, and further preferably a compound having a molecular weight of less than 500.

Examples of the low-molecular hydrophilic compound include water-soluble organic compounds. Examples of the water-soluble organic compound include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, ether or ester derivatives thereof, polyhydric alcohols such as glycerin, pentaerythritol, and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine, diethanolamine, and monoethanolamine, salts thereof, organic sulfonic acids such as alkylsulfonic acid, p-toluenesulfonic acid, and benzenesulfonic acid, organic aminosulfonic acids such as alkylsulfonic acid, salts thereof, organic acids such as alkylsulfuric acid and alkylethersulfuric acid, salts thereof, organic phosphonic acids such as phenylphosphonic acid, salts thereof, organic carboxylic acids such as tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and amino acids, salts thereof, and betaines.

The low-molecular hydrophilic compound preferably contains at least 1 selected from the group consisting of polyols, organic sulfates, organic sulfonates, and betaines.

Specific examples of the organic sulfonate include alkylsulfonates such as n-butylsodium sulfonate, n-hexylsodium sulfonate, 2-ethylhexylsodium sulfonate, cyclohexylsodium sulfonate, and n-octylsodium sulfonate; alkyl sulfonates containing an oxyethylene chain, such as 5,8, 11-trioxadecane-1-sulfonic acid sodium salt, 13-ethyl-5, 8, 11-trioxadecane-1-sulfonic acid sodium salt, 5,8,11, 14-tetraoxatetracosane-1-sulfonic acid sodium salt; sodium benzenesulfonate, sodium p-toluenesulfonate, sodium p-hydroxybenzenesulfonate, sodium p-styrenesulfonate, dimethyl isophthalate-5-sulfonate, sodium 1-naphthylsulfonate, sodium 4-hydroxynaphthalenesulfonate, disodium 1, 5-naphthalenedisulfonate, trisodium 1,3, 6-naphthalenetrisulfonate and the like, and compounds described in paragraphs 0026 to 0031 of Japanese patent laid-open No. 2007 and 276454 and paragraphs 0020 to 0047 of Japanese patent laid-open No. 2009 and 154525 and the like. The salt can be potassium salt or lithium salt.

Examples of the organic sulfates include sulfates of alkyl, olefin, alkynyl, aryl or heterocyclic monoether of polyethylene oxide. The number of ethylene oxide units is preferably 1 to 4, and the salt is preferably a sodium salt, a potassium salt or a lithium salt. Specific examples thereof include compounds described in paragraphs 0034 to 0038 of Japanese patent application laid-open No. 2007-276454.

The betaine is preferably a compound having 1 to 5 carbon atoms in the hydrocarbon substituent of the nitrogen atom, and specific examples thereof include trimethylammonium acetate, dimethylpropylammonium acetate, 3-hydroxy-4-trimethylammonium butyrate, 4- (1-pyridyl) butyrate, 1-hydroxyethyl-1-imidazolium acetate, trimethylammonium methanesulfonate, dimethylpropylammonium methanesulfonate, 3-trimethylammonium-1-propanesulfonate, and 3- (1-pyridyl) -1-propanesulfonate.

Since the low-molecular hydrophilic compound has a small structure of the hydrophobic portion and hardly has a surface active effect, the fountain solution does not penetrate into the exposed portion (image portion) of the image recording layer to reduce the hydrophobicity or the film strength of the image portion, and the ink-receiving property or the brushing resistance of the image recording layer can be favorably maintained.

The content of the low-molecular hydrophilic compound is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 2 to 10% by mass, based on the total mass of the image recording layer. Within this range, good on-press developability and brush resistance can be obtained.

The low-molecular hydrophilic compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

[ sensitizer ]

The image recording layer may contain a sensitizer such as a phosphonium compound, a nitrogen-containing low-molecular-weight compound, or an ammonium group-containing polymer for improving the ink-receptivity. In particular, when the protective layer contains an inorganic layered compound, these compounds function as a surface covering agent for the inorganic layered compound, and can suppress a decrease in the ink adhesion during printing with the inorganic layered compound.

The sensitizer is preferably used in combination with a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer, and more preferably used in combination with a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer.

Examples of the phosphonium compound include those described in Japanese patent laid-open Nos. 2006-297907 and 2007-50660. Specific examples thereof include tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1, 4-bis (triphenylphosphine) butane-bis (hexafluorophosphate), 1, 7-bis (triphenylphosphine) heptane-sulfate, 1, 9-bis (triphenylphosphine) nonane-naphthalene-2, 7-disulfonate, and the like.

Examples of the nitrogen-containing low-molecular-weight compound include amine salts and quaternary ammonium salts. Furthermore, imidazolinium salts, benzimidazolinium salts, pyridinium salts and quinolinium salts are also included. Among them, quaternary ammonium salts and pyridinium salts are preferable. Specific examples thereof include tetramethylammonium ═ hexafluorophosphate, tetrabutylammonium ═ hexafluorophosphate, dodecyltrimethylammonium ═ p-toluenesulfonic acid, benzyltriethylammonium ═ hexafluorophosphate, benzyldimethyloctylammonium ═ hexafluorophosphate, benzyldimethyldodecylammonium ═ hexafluorophosphate, the compounds described in paragraphs 0021 to 0037 of Japanese patent laid-open No. 2008-284858 and paragraphs 0030 to 0057 of Japanese patent laid-open No. 2009-090645.

The ammonium group-containing polymer may have an ammonium group in its structure, and is preferably a polymer containing 5 to 80 mol% of a (meth) acrylate having an ammonium group in a side chain as a copolymerization component. Specific examples thereof include polymers described in paragraphs 0089 to 0105 of Japanese patent application laid-open No. 2009-208458.

In the ammonium salt-containing polymer, the reduced viscosity (unit: ml/g) value determined by the measurement method described in Japanese patent laid-open No. 2009-208458 is preferably in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100. When the reduced viscosity is converted into a weight average molecular weight (Mw), the reduced viscosity is preferably 10,000 to 150,000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000.

Specific examples of the ammonium group-containing polymer are shown below.

(1)2- (Trimethylammonium) ethylmethacrylate/p-toluenesulfonate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 10/90, Mw4.5 ten thousand)

(2)2- (Trimethylammonium) ethyl methacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw6.0 ten thousand)

(3)2- (ethyldimethylammonium) ethylmethacrylate copolymer p-toluenesulfonate/hexyl methacrylate (molar ratio 30/70, Mw4.5 ten thousand)

(4)2- (trimethylammonium) ethylmethacrylate hexafluorophosphate/2-ethylhexyl methacrylate copolymer (molar ratio 20/80, Mw6.0 ten thousand)

(5)2- (trimethylammonium) ethylmethacrylate copolymer methyl sulfate/hexyl methacrylate (molar ratio 40/60, mw7.0 ten thousand)

(6)2- (Butyldimethylammonium) ethylmethacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 25/75, Mw6.5 ten thousand)

(7)2- (Butyldimethylammonium) ethacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw6.5 ten thousand)

(8)2- (Butyldimethylammonium) ethylmethacrylate 13-ethyl-5, 8, 11-trioxa-1-heptadecane sulfonate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw7.5 ten thousand)

(9)2- (Butyldimethylammonium) Ethyl methacrylate Hexafluorophosphoric acid/3, 6-dioxaheptyl methacrylate/2-hydroxy-3-methacryloxypropyl methacrylate copolymer (molar ratio 15/80/5, Mw6.5 ten thousand)

The content of the sensitizer is preferably 0.01 to 30.0% by mass, more preferably 0.1 to 15.0% by mass, and still more preferably 1 to 10% by mass, based on the total mass of the image recording layer.

[ other Components ]

The image recording layer may contain a surfactant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layered compound, and the like as other components. Specifically, reference can be made to the description of paragraphs 0114 to 0159 of japanese patent application laid-open No. 2008-284817.

[ formation of image recording layer ]

The image-recording layer in the lithographic printing plate precursor according to the present invention can be formed by: for example, as described in paragraphs 0142 to 0143 of jp 2008-a-195018, a coating liquid is prepared by dispersing or dissolving the above components as required in a known solvent, and the coating liquid is applied to a support by a known method such as bar coater coating and dried. The amount of the image recording layer (solid content) after coating and drying varies depending on the application, but is preferably 0.3g/m²～3.0g/m². Within this range, good sensitivity and good film properties of the image recording layer can be obtained.

As the solvent, a known solvent can be used. Specific examples thereof include water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, dichloroethane, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N-dimethylformamide, dimethyl sulfoxide, and the like, Gamma-butyrolactone, methyl lactate, ethyl lactate, and the like. The solvent may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The solid content concentration in the coating liquid is preferably about 1 to 50 mass%.

The amount of the image recording layer (solid content) after coating and drying is determined according to the purposeIn view of obtaining good sensitivity and good film characteristics of the image recording layer, 0.3 to 3.0g/m is preferable²Left and right.

< undercoat layer >

The lithographic printing plate precursor according to the present invention preferably has an undercoat layer (also sometimes referred to as an intermediate layer) between the image-recording layer and the support. The undercoat layer enhances adhesion between the support and the image recording layer in the exposed portion, and easily peels off from the support of the image recording layer in the unexposed portion, thereby contributing to improvement of the developability without impairing the brushing resistance. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat-insulating layer, and thus the effect of preventing the sensitivity from being lowered by the diffusion of heat generated by exposure to the support is also exhibited.

Examples of the compound used for the undercoat layer include polymers having an adsorptive group and a hydrophilic group, which can be adsorbed on the surface of the support. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group and further having a crosslinkable group is preferable. The compound used in the undercoat layer may be a low molecular compound or a polymer. The compound used in the undercoat layer may be used by mixing 2 or more compounds, if necessary.

When the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferable.

As the adsorptive group capable of being adsorbed on the surface of the support, phenolic hydroxyl group, carboxyl group, -PO are preferable₃H₂、-OPO₃H₂、-CONHSO₂-、-SO₂NHSO₂-、-COCH₂COCH₃. As the hydrophilic group, a sulfo group or a salt thereof, or a salt of a carboxyl group is preferable. The crosslinkable group is preferably an acryloyl group, a methacryloyl group, an acrylamide group, a methacrylamide group, an allyl group or the like.

The polymer may have a crosslinkable group introduced by formation of a salt of a compound having a polar substituent of the polymer, a substituent having the polar substituent and charged particles, and an ethylenically unsaturated bond, or may further copolymerize a monomer other than the above, preferably a hydrophilic monomer.

Specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in Japanese patent application laid-open No. 10-282679 and a phosphorus compound having an ethylenic double bond reactive group described in Japanese patent application laid-open No. 2-304441 are preferable. The crosslinkable group (preferably, an ethylenically unsaturated bond group), the functional group that interacts with the surface of the support, and the low-molecular or high-molecular compound having a hydrophilic group described in each of Japanese patent application laid-open Nos. 2005-238816, 2005-125749, 2006-239867, and 2006-215263 can also be preferably used.

More preferred polymers include high-molecular polymers having an adsorptive group, a hydrophilic group and a crosslinkable group, which are capable of being adsorbed on the surface of a support, as described in jp 2005-125749 and jp 2006-188038 a.

The content of the ethylenically unsaturated bond group in the polymer used in the undercoat layer is preferably 0.1 to 10.0mmol, more preferably 0.2 to 5.5mmol, per 1g of the polymer.

The weight average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, and more preferably 1 to 30 ten thousand.

The undercoat layer may contain, in addition to the compound for undercoat layer, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, a compound having an amino group or a functional group having polymerization inhibiting ability and a group that interacts with the surface of the support (for example, 1, 4-diazabicyclo [2.2.2] octane (DABCO), 2,3,5, 6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.) in order to prevent fouling with time.

The primer layer can be applied by a known method. The amount of the primer coating (solid content) is preferably 0.1mg/m²～100mg/m²More preferably 1mg/m²～30mg/m²。

< protective layer >

The lithographic printing plate precursor according to the present invention preferably has a protective layer (also sometimes referred to as an overcoat) on the image-recording layer. The protective layer has a function of inhibiting an image formation inhibition reaction by blocking oxygen, and also has a function of preventing the generation of scratches in the image recording layer and preventing ablation during exposure to a high-illuminance laser.

Protective layers having such characteristics are described in, for example, U.S. Pat. No.3,458,311 and Japanese patent publication No. 55-049729. As the low oxygen permeability polymer used for the protective layer, any of a water-soluble polymer and a water-insoluble polymer can be appropriately selected and used, and 2 or more kinds thereof can be mixed and used as necessary. Specific examples thereof include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, and poly (meth) acrylonitrile.

As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxyl group or a sulfo group can be preferably used. Specifically, modified polyvinyl alcohols described in Japanese patent application laid-open Nos. 2005-250216 and 2006-259137 are mentioned.

The protective layer preferably contains an inorganic layered compound for improving oxygen barrier properties. The inorganic layered compound is a particle having a thin flat plate shape, and examples thereof include mica groups such as natural mica and synthetic mica, and a particle having a structure represented by the formula: 3 MgO.4 SiO.H₂Talc, taeniolite, montmorillonite, saponite, hectorite, zirconium phosphate, etc., represented by O.

The inorganic layered compound preferably used is a mica compound. Examples of the mica compound include compounds represented by the formula: a (B, C)_2-5D₄O₁₀(OH，F，O)₂Wherein A is any one of K, Na and Ca, B and C are any one of Fe (II), Fe (III), Mn, Al, Mg and V, and D is Si or Al. Mica groups such as natural mica and synthetic mica.

In the mica group, examples of natural mica include muscovite, paragonite, phlogopite, biotite, and lepidolite. Examples of the synthetic mica include fluorophlogopiteKMg₃(AlSi₃O₁₀)F₂Mica with potassium tetrasilicate KMg_2.5(Si₄O₁₀)F₂Equal non-swelling mica and sodium tetrasilicate mica NaMg_2.5(Si₄O₁₀)F₂Na or Li with mica (Na, Li) Mg₂Li(Si₄O₁₀)F₂Montmorillonite series Na or Li hectorite (Na, Li)_1/8Mg_2/5Li_1/8(Si₄O₁₀)F₂And swelling mica. Further, synthetic montmorillonite is also useful.

Among the mica compounds, fluorine-based swellable mica is particularly useful. Namely, the swelling synthetic mica has a structure consisting of

The metal atoms in the lattice are significantly substituted more than other clay minerals in a laminated structure composed of unit lattice layers with a thickness of about two. As a result, the lattice layers cause a shortage of positive charge, and Li is adsorbed between the layers to compensate for the positive charge⁺、Na⁺、Ca²⁺、Mg²⁺And the like. The cations interposed between these layers are called exchangeable cations, and can be exchanged with various cations. In particular, when the cations between the layers are Li + and Na +, the bonding between the layered lattices is weak due to a small ionic radius, and large swelling occurs due to water. When a shear force is applied in this state, the sol is easily broken and a stable sol is formed in water. This tendency of the swellable synthetic mica is strong, and it can be particularly preferably used.

From the viewpoint of diffusion control, the shape of the mica compound is preferably as thin as possible, and the larger the plane size is within a range not inhibiting the smoothness of the coated surface or the transmittance of the actinic ray. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is a ratio of the major axis to the thickness of the particle, and can be measured, for example, from a projection view of a photomicrograph of the particle. The larger the aspect ratio, the greater the effect obtained. The upper limit of the aspect ratio is not limited, and may be, for example, 1000 or less.

The average major axis of the particle diameter of the mica compound is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. The average thickness of the particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less. Specifically, for example, in the case of swellable synthetic mica, which is a typical compound, the thickness is preferably about 1nm to 50nm and the plane size (major axis) is preferably about 1 μm to 20 μm.

The content of the inorganic layered compound is preferably 1 to 60% by mass, and more preferably 3 to 50% by mass, based on the total solid content of the protective layer. Even when a plurality of inorganic layered compounds are used simultaneously, the total amount of the inorganic layered compounds is preferably the above amount. The oxygen barrier property is improved in the above range, and good sensitivity is obtained. Further, the ink-applying property can be prevented from being lowered.

The protective layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coatability, and inorganic particles for controlling surface slipperiness. The protective layer may contain a sensitizer described in the image recording layer.

The protective layer is applied by a known method. The coating amount (solid content) of the protective layer is preferably 0.01g/m²～10g/m²More preferably 0.02g/m²～3g/m²Particularly preferably 0.02g/m²～1g/m²。

(method for producing planographic printing plate)

The lithographic printing plate precursor of the present invention can be subjected to image exposure and development treatment to produce a lithographic printing plate.

The method for producing a lithographic printing plate according to the present invention preferably includes a step of exposing the lithographic printing plate precursor according to the present invention in an image form to form exposed portions and unexposed portions (hereinafter, also referred to as "exposure step"), and a step of supplying at least one of a printing ink and a fountain solution to remove the unexposed portions (hereinafter, also referred to as "on-press development step").

In another embodiment of the method for producing a lithographic printing plate according to the present invention, it is preferable that the method includes an exposure step of exposing the lithographic printing plate precursor according to the present invention to form an image and forming an exposed portion and an unexposed portion, and a step of supplying a developer having a pH of 2 or more and 11 or less to remove the unexposed portion (hereinafter, also referred to as a "development step").

Hereinafter, preferred embodiments of the method for manufacturing a lithographic printing plate according to the present invention and the steps of the lithographic printing method according to the present invention will be described in order. The lithographic printing plate precursor according to the present invention can be developed with a developer.

< Exposure Process >

The method for producing a lithographic printing plate according to the present invention preferably includes an exposure step of exposing the lithographic printing plate precursor according to the present invention in an image form to form exposed portions and unexposed portions. The lithographic printing plate precursor according to the present invention is preferably subjected to laser exposure through a transparent original having a line image, a halftone image, or the like, or to exposure in an image form by laser beam scanning or the like based on digital data.

Light sources with wavelengths of 750nm to 1,400nm are preferably used. As the light source of 750nm to 1,400nm, solid-state lasers and semiconductor lasers radiating infrared rays are preferable. Regarding the infrared laser, the output is preferably 100mW or more, the exposure time per 1 pixel is preferably 20 microseconds or less, and the irradiation energy is preferably 10mJ/cm²～300mJ/cm². Also, in order to shorten the exposure time, a multi-beam laser apparatus is preferably used. The exposure mechanism may be any of an inner drum system, an outer drum system, a flat plate system, and the like.

The image exposure can be performed by a conventional method using a plate setter or the like. In the case of on-press development, after the lithographic printing plate precursor is mounted on a printing press, image exposure may be performed on the printing press.

< on-machine development Process >

The method of manufacturing a lithographic printing plate according to the present invention preferably includes an on-press development step of supplying at least one of a printing ink and a fountain solution to remove the unexposed portion.

The method of manufacturing the lithographic printing plate according to the present invention can be performed by a method of developing with a developer (developer processing method).

Hereinafter, an on-machine development method will be described.

[ on-machine development method ]

In the on-press development method, the lithographic printing plate precursor subjected to image exposure is preferably supplied with an oil-based ink and an aqueous component on a printing press, and the image-recording layer in the non-image portion is removed to produce a lithographic printing plate.

That is, when the lithographic printing plate precursor is directly mounted on a printing press without any development treatment after image exposure or is mounted on a printing press and then subjected to image exposure on the printing press and then to printing by supplying the oil-based ink and the aqueous component, in the initial stage during printing, the non-image portion is removed by dissolving or dispersing the uncured image recording layer with either or both of the supplied oil-based ink and aqueous component, and the hydrophilic surface is exposed in the portion. On the other hand, in the exposure section, an oil-based ink receiving section having an oleophilic surface is formed by exposing the cured image recording layer. The ink to be supplied to the printing surface first may be an oil-based ink or an aqueous component, but from the viewpoint of preventing contamination due to the components of the image recording layer from which the aqueous component is removed, it is preferable to supply the oil-based ink first. In this way, the lithographic printing plate precursor is developed on a printing press machine and used directly for printing a plurality of sheets. As the oil-based ink and the aqueous component, a general printing ink for offset printing and a fountain solution can be preferably used.

As the laser for image-exposing the lithographic printing plate precursor according to the present invention, the wavelength of the light source is preferably 300nm to 450nm or 750nm to 1,400 nm. In the case of a light source of 300nm to 450nm, a lithographic printing plate precursor containing a sensitizing dye having an absorption maximum in the wavelength range in the image recording layer is preferably used, and the above light source is preferably used as a light source of 750 to 1,400 nm. As the light source of 300nm to 450nm, a semiconductor laser is preferable.

[ developer treatment method ]

The lithographic printing plate precursor according to the present invention can be used to produce a lithographic printing plate by appropriately selecting the polymer a, binder polymer, and the like as components of the image recording layer, and by performing a development treatment using a developer. The developing treatment using the developing solution includes: a method of using a developer having a pH of 2-11, which may contain at least 1 compound selected from the group consisting of surfactants and water-soluble polymer compounds (also referred to simply as a developing treatment).

The developing solution may contain a water-soluble polymer compound or the like as necessary, so that the developing and the gum solution treatment steps can be performed simultaneously.

Accordingly, the post-washing step is not particularly required, and the drying step may be performed after the development and the gum solution treatment are performed in 1-liquid-1 step. Therefore, as the development treatment using the developer, a method for producing a lithographic printing plate including a step of developing the lithographic printing plate precursor after image exposure with a developer having a pH of 2 to 11 is preferable. After the development treatment, it is preferable to remove the remaining developer using a squeegee roller and then dry it.

That is, in the developing step of the method for manufacturing a lithographic printing plate according to the present invention, it is preferable to perform the developing treatment and the gum solution treatment in 1 liquid-1 step.

The developing and gum solution treatment in 1-liquid-1 process means as follows: the developing treatment and the gum solution treatment were not performed in separate steps, but performed in 1 step with 1 liquid.

The developing process can be preferably performed by an automatic developing processor including a supply device for the developer and a wiping member. As the wiping member, an automatic developing processor using a rotating brush roller is particularly preferable.

The number of the rotating brush rolls is preferably more than 2. Further, it is preferable that the automatic development processor includes a drying device such as a device for removing excess developer such as a squeegee roller or a warm air device on the back surface of the development processing device. The automatic development processor may further include a pre-heating device for heating the lithographic printing plate precursor after image exposure in front of the development processing device.

The processing in such an automatic development processor is advantageous in that it is not necessary to perform processing of development residues from an image recording layer (and a protective layer in the case where a lithographic printing plate precursor has a protective layer) generated in the case of a so-called on-press development processing.

In the case of the manual processing in the developing step, as a developing treatment method, for example, a method of applying a water solution to a sponge, cotton wool, or the like while wiping the entire surface of the plate, and drying after the completion of the treatment is preferably mentioned. In the case of the dipping treatment, for example, a method of dipping the lithographic printing plate precursor in a tank, a deep tank, or the like containing an aqueous solution for about 60 seconds and stirring, and then drying while wiping with absorbent cotton, sponge, or the like is preferably used.

In the developing treatment, an apparatus having a simplified structure and a simplified process is preferably used.

For example, in the alkali development treatment, the protective layer is removed by a pre-water washing step, followed by development with an alkali developer having a high pH, and then, the alkali is removed in a post-water washing step, and the resist treatment is performed in a resist coating step, followed by drying in a drying step. In a simple development process, development and application of glue can be performed simultaneously with 1 liquid. Accordingly, the post-washing step and the glue treatment step can be omitted, and it is preferable to perform the developing and glue application (glue solution treatment) with the solution 1 and then perform the drying step as needed.

It is further preferable that the removal of the protective layer, the development and the application of the paste are performed simultaneously with the liquid 1 without performing the pre-washing step. After the development and the coating, it is preferable to remove the remaining developer by a squeeze roller and then dry the developer.

In the developing step, the lithographic printing plate precursor may be immersed in the developer 1 time, or may be immersed more than 2 times. Among them, a method of immersing the lithographic printing plate precursor 1 or 2 times in the above-described developer is preferable.

The immersion may be carried out in a developer tank in which a developer is stored, or the developer may be sprayed from an aerosol or the like onto the plate surface of the lithographic printing plate precursor subjected to exposure.

Even when the developing solution is immersed 2 times or more, the same developing solution or a developing solution (fatigue solution) in which the components of the image recording layer are dissolved or dispersed by the developing solution and the developing treatment is immersed 2 times or more, and the immersion is referred to as a developing treatment in 1 liquid (1 liquid treatment).

In the developing treatment, a wiping member is preferably used, and a wiping member such as a brush is preferably provided in the developing bath for removing the non-image portion of the image recording layer.

The development treatment is carried out by, for example, immersing the exposed lithographic printing plate precursor in a developer at a temperature of preferably 0 to 60 ℃, more preferably 15 to 40 ℃, and wiping with a brush or sucking a treatment liquid contained in an external tank with a pump, spraying from an aerosol nozzle, and wiping with a brush, according to a usual method. These developing treatments can be continuously performed a plurality of times. For example, after the developer contained in the external tank is pumped up and discharged from the aerosol nozzle and wiped with a brush, the developer can be discharged from the aerosol nozzle again and wiped with a brush. In the case of performing the developing process using the automatic developing machine, it is preferable to recover the throughput using the assist liquid or the fresh developer because the developer becomes fatigued due to an increase in the throughput.

In the development process, a conventionally known paste coater or automatic developing machine used for a PS Plate (pre-coated Plate) or CTP (Computer to Plate) can be used. When an automatic developing machine is used, for example, any of a method of performing a process by sucking a developer contained in a developing tank or a developer contained in an external tank with a pump and spraying the developer from an aerosol nozzle, a method of performing a process by immersing and carrying a printing plate in a tank filled with a developer by a guide roller or the like in a liquid, and a so-called one-shot method of performing a process by supplying a required amount of a developer that is not used substantially to each plate can be applied. In either embodiment, a system having a wiping mechanism by a brush, a double-sided pile, or the like is more preferable. For example, a commercially available automatic developing machine (e.g., Clean Out Unit C85/C125, Clean-OutUnit + C85/120, FCF 85V, FCF 125V, FCF News (manufactured by Glanz & Jensen Co., Ltd.)), Azuria CX85, Azuri CX125, and Azuri CX150 (manufactured by AGFA GRAPHICS Co., Ltd.)) can be used. Further, a device in which the laser exposure unit and the automatic developing machine unit are integrally incorporated can be used.

The following is a detailed description of the components of the developer used in the developing step and the like.

-pH-

The pH of the developer is preferably 2 to 11, more preferably 5 to 9, and further preferably 7 to 9. From the viewpoint of developability and dispersibility of the image recording layer, it is advantageous to set the pH value high, but it is effective to set the pH value low for printability, particularly for inhibition of stains.

Here, the pH was measured at 25 ℃ using a pH meter (model: HM-31, manufactured by DKK-TOA CORPORATION).

Surfactants-

The developer may contain a surfactant such as an anionic surfactant, a nonionic surfactant, a cationic surfactant, or an amphoteric surfactant.

From the viewpoint of brush staining properties, the developer preferably contains at least 1 selected from the group consisting of anionic surfactants and amphoteric surfactants.

The developer preferably contains a nonionic surfactant, more preferably contains a nonionic surfactant and at least 1 selected from the group consisting of anionic surfactants and amphoteric surfactants.

As the anionic surfactant, a compound represented by the following formula (I) can be preferably mentioned.

R¹-Y¹-X¹(I)

In the formula (I), R¹Represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group which may have a substituent.

The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, and an octadecyl group.

The cycloalkyl group may be of a monocyclic type or a polycyclic type. The monocyclic ring is preferably a monocyclic cycloalkyl group having 3 to 8 carbon atoms, and more preferably a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, or a cyclooctyl group. Examples of the polycyclic group include an adamantyl group, a norbornyl group, an isobornyl group, a camphoryl group, a dicyclopentyl group, an α -sulfoyl group, and a tricyclodecyl group.

The alkenyl group is preferably an alkenyl group having 2 to 20 carbon atoms, and specific examples thereof include a vinyl group, an allyl group, a butenyl group, and a cyclohexenyl group.

The aralkyl group is preferably an aralkyl group having 7 to 12 carbon atoms, and specifically, a benzyl group, a phenethyl group, a naphthylmethyl group, and the like can be preferably mentioned.

The aryl group is preferably an aryl group having 6 to 15 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group, a dimethylphenyl group, a2, 4, 6-trimethylphenyl group, a naphthyl group, an anthryl group, a 9, 10-dimethoxyanthryl group and the like.

As the substituent, a monovalent non-metal radical from which a hydrogen atom is removed can be used, and preferable examples thereof include a halogen atom (F, Cl, Br, or I), a hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an amide group, an ester group, an acyloxy group, a carboxyl group, a carboxylic acid group anion group, a sulfonic acid group anion group, and the like.

Specific examples of the alkoxy group in the substituent include an alkoxy group having preferably 1 to 40 carbon atoms, and more preferably 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a pentoxy group, a hexoxy group, a dodecoxy group, a stearyloxy group, a methoxyethoxy group, a poly (ethoxy) group, and a poly (propoxy) group. Examples of the aryloxy group include aryloxy groups having 6 to 18 carbon atoms such as a phenoxy group, a tolyloxy group, a xylyloxy group, a mesityloxy group, a cumene oxy group, a methoxyphenoxy group, an ethoxyphenoxy group, a chlorophenoxy group, a bromophenoxy group, and a naphthyloxy group. Examples of the acyl group include acyl groups having 2 to 24 carbon atoms such as an acetyl group, a propionyl group, a butyryl group, a benzoyl group, and a naphthoyl group. Examples of the amide group include amide groups having 2 to 24 carbon atoms such as an acetamido group, a propionamido group, a dodecanoamido group, a palmitoylamino group, a stearamido group, a benzoyl group, and a naphthoylamino group. Examples of the acyloxy group include acyloxy groups having 2 to 20 carbon atoms such as an acetoxy group, a propionyloxy group, a benzoyloxy group, and a naphthoyloxy group. Examples of the ester group include ester groups having 1 to 24 carbon atoms such as a methyl ester group, an ethyl ester group, a propyl ester group, a hexyl ester group, an octyl ester group, a dodecyl ester group, and a stearyl ester group. The substituent may be a combination of two or more of the above substituents.

X¹Represents a sulfonate group, a sulfate monoester group, a carboxylate group or a phosphate group.

Y¹Represents a single bond, -C_nH_2n-、-C_n-mH_2(n-m)OC_mH_2m-、-O-(CH₂CH₂O)_n-、-O-(CH₂CH₂CH₂O)_n-, -CO-NH-or a 2-valent linking group consisting of a combination of these 2 or more, n.gtoreq.1 and n.gtoreq.m.gtoreq.0.

Among the compounds represented by the formula (I), compounds represented by the following formula (I-A) or formula (I-B) are preferable from the viewpoint of scratch contamination resistance.

[ chemical formula 13]

In the formulae (I-A) and (I-B), R^A1～R^A10Each independently represents a hydrogen atom or an alkyl group, nA represents an integer of 1 to 3, X^A1And X^A2Each independently represents a sulfonate group, a sulfate monoester group, a carboxylate group or a phosphate group, Y^A1And Y^A2Each independently represents a single bond, -C_nH_2n-、-C_n-mH_2(n-m)OC_mH_2m-、-O-(CH₂CH₂O)_n-、-O-(CH₂CH₂CH₂O)_n-, -CO-NH-or mixtures of these2 or more linking groups of valence 2 are combined, n is not less than 1 and n is not less than m is not less than 0, R^A1～R^A5Or R^A6～R^A10Neutralization of Y^A1Or Y^A2The total number of carbon atoms in (2) is 3 or more.

R in the compound represented by the above formula (I-A) or formula (I-B)^A1～R^A5And Y^1AOr R^A6～R^A10And Y^A2The total carbon number of (2) is preferably 25 or less, more preferably 4 to 20. The structure of the alkyl group may be a straight chain or a branched chain.

X in the compound represented by the formula (I-A) or the formula (I-B)^A1And X^A2Preferably sulfonate or carboxylate groups. And, X^A1And X^A2Among the salt structures in (1), alkali metal salts are particularly preferable because they have good solubility in aqueous solvents. Among them, sodium salt or potassium salt is particularly preferable.

As the compounds represented by the above formula (I-A) or formula (I-B), reference can be made to the description in paragraphs 0019 to 0037 of Japanese patent laid-open publication No. 2007-206348.

As the anionic surfactant, the compounds described in paragraphs 0023 to 0028 of Japanese patent application laid-open No. 2006-065321 can also be preferably used.

The amphoteric surfactant used in the developer is not particularly limited, but examples thereof include amine oxide systems such as alkyldimethylamine oxide, betaine systems such as alkylbetaine, fatty acid amide propylbetaine, and alkylimidazole, and amino acid systems such as sodium alkyl amino fatty acid.

It is particularly preferable to use an alkyldimethylamine oxide which may have a substituent, an alkylbetaine carboxyl group which may have a substituent, and an alkylsulfobetaine which may have a substituent. Specific examples thereof include compounds represented by the formula (2) in paragraph 0256 of jp 2008-one 203359, compounds represented by the formulae (I), (II) and (VI) in paragraph 0028 of jp 2008-one 276166, and compounds described in paragraphs 0022 to 0029 of jp 2009-one 047927.

As the amphoteric surfactant used in the developer, a compound represented by the following formula (1) or a compound represented by the formula (2) is preferable.

[ chemical formula 14]

In the formulae (1) and (2), R¹And R¹¹Each independently represents an alkyl group having 8 to 20 carbon atoms or an alkyl group having a linking group having 8 to 20 carbon atoms in total.

R²、R³、R¹²And R¹³Each independently represents a hydrogen atom, a group having an alkyl group or an oxirane structure.

R⁴And R¹⁴Each independently represents a single bond or an alkylene group.

And, R¹、R²、R³And R⁴2 groups in (A) may be bonded to each other to form a ring structure, R¹¹、R¹²、R¹³And R¹⁴The 2 groups in (1) may be bonded to each other to form a ring structure.

In the compound represented by the above formula (1) or the compound represented by the formula (2), when the total carbon number is increased, the hydrophobic portion is increased, and the solubility of the aqueous system in the developer is decreased. In this case, the solubility is improved by mixing an organic solvent such as alcohol which contributes to dissolution with water as a dissolution aid, but if the total carbon number value becomes too large, the surfactant cannot be dissolved in an appropriate mixing range. Thus, R¹～R⁴Or R¹¹～R¹⁴The total number of carbon atoms of (a) is preferably 10 to 40, more preferably 12 to 30.

Having a structure represented by R¹Or R¹¹The alkyl group of the linker represents a structure having a linker between alkyl groups. That is, when the number of the linker is 1, the linker may be represented by "— alkylene-linker-alkyl". Examples of the linker include an ester bond, a carbonyl bond, and an amide bond. The linking group may be two or more, but is preferably 1, and particularly preferably an amide bond. The total number of carbon atoms of the alkylene group bonded to the linking group is preferably 1 to 5.The alkylene group may be linear or branched, but is preferably a linear alkylene group. The alkyl group bonded to the linking group is preferably a linear alkyl group, although it has 3 to 19 carbon atoms and may be a linear chain or a branched chain.

R²Or R¹²In the case of an alkyl group, the number of carbon atoms is preferably 1 to 5, and particularly preferably 1 to 3. The alkyl group may be either a straight chain or a branched chain, but is preferably a straight chain alkyl group.

R³Or R¹³In the case of an alkyl group, the number of carbon atoms is preferably 1 to 5, and particularly preferably 1 to 3. The alkyl group may be either a straight chain or a branched chain, but is preferably a straight chain alkyl group.

As containing R³Or R¹³Examples of the group having an oxirane structure include a group represented by the formula-R^a(CH₂CH₂O)_nR^bThe group shown. Herein, R is^aRepresents a single bond, an oxygen atom or a 2-valent organic group (preferably having 10 or less carbon atoms), R^bRepresents a hydrogen atom or an organic group (preferably, a carbon number of 10 or less), and n represents an integer of 1 to 10.

R⁴And R¹⁴In the case of an alkylene group, the number of carbon atoms is preferably 1 to 5, and particularly preferably 1 to 3. The alkylene group may be either linear or branched, but is preferably a linear alkylene group.

The compound represented by the formula (1) or the compound represented by the formula (2) preferably has an amide bond, more preferably as R¹Or R¹¹The linker of (3) has an amide bond.

Representative examples of the compound represented by the formula (1) or the compound represented by the formula (2) are shown below, but the present invention is not limited to these.

[ chemical formula 15]

[ chemical formula 16]

[ chemical formula 17]

The compound represented by the formula (1) or (2) can be synthesized according to a known method. Further, commercially available compounds can also be used. Commercially available compounds represented by the formula (1) include Softazoline LPB manufactured by Kawaken Fine Chemicals Co., Ltd., Softazoline LPB-R manufactured by Ltd., Vista MAP, Takemoto Oil & Fat Co., Ltd., Takesurf C-157L manufactured by Ltd. Examples of the compound represented by the formula (2) include Softazoline LAO manufactured by Kawaken Fine Chemicals co., ltd., AMOGEN AOL manufactured by DKS co.

The amphoteric surfactant may be used alone in a developer in an amount of 1 kind, or may be used in combination with 2 or more kinds.

Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyrene phenyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerol fatty acid partial esters, polyoxyethylene glycerin fatty acid partial esters, polyoxyethylene diglycols, fatty acid diethanolamides, and N, n-bis-2-hydroxyalkylamines, polyoxyethylenealkylamines, triethanolamine fatty acid esters, trialkylammonium oxides, polyoxyethylenealkylphenyl ethers, polyoxyethylene-polyoxypropylene block copolymers, and the like.

Also, surfactants such as acetylene glycol-based and acetylene alcohol-based ethylene oxide adducts and fluorine-based surfactants can be used in the same manner. These surfactants can also be used in combination of 2 or more.

The nonionic surfactant is preferably a nonionic aromatic ether surfactant represented by the following formula (N1).

X^N-Y^N-O-(A¹)_nB-(A²)_mB-H (N1)

In the formula, X^NRepresents an aromatic group which may have a substituent, Y^NRepresents a single bond or an alkylene group having 1 to 10 carbon atoms, A¹And A²Are different groups from each other and represent-CH₂CH₂O-or-CH₂CH(CH₃) And any one of O-, nB and mB independently represent an integer of 0 to 100, wherein nB and mB are not 0 at the same time, and nB and mB are not 1 when nB and mB are 0.

In the formula, as X^NExamples of the aromatic group of (2) include a phenyl group, a naphthyl group, and an anthryl group. These aromatic groups may have a substituent. Examples of the substituent include an organic group having 1 to 100 carbon atoms. In the formula, when both a and B are present, the copolymer may be random or block.

Specific examples of the organic group having 1 to 100 carbon atoms include aliphatic hydrocarbon groups which may be saturated or unsaturated and may be linear or branched, aromatic hydrocarbons such as alkyl, alkenyl, alkynyl, aryl, aralkyl and the like, and alkoxy, aryloxy, N-alkylamino, N-dialkylamino, N-arylamino, N-diarylamino, N-alkyl-N-arylamino, acyloxy, carbamoyloxy, N-alkylcarbamoyloxy, N-arylcarbamoyloxy, N-dialkylcarbamoyloxy, N-diarylcarbamoyloxy, N-alkyl-N-arylcarbamoyloxy, acylamino, N-alkylamido, N-arylacylamino, aryl-acylamino, aralkyl, and the like, An acyl group, an alkoxycarbonylamino group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an N-alkylcarbamoyl group, an N, N-dialkylcarbamoyl group, an N-arylcarbamoyl group, an N, N-diarylcarbamoyl group, an N-alkyl-N-arylcarbamoyl group, a polyoxyalkylene chain, the above-mentioned organic group to which a polyoxyalkylene chain is bonded, and the like. The alkyl group may be linear or branched.

Further, as the nonionic surfactant, the compounds described in paragraphs 0030 to 0040 of Japanese patent application laid-open No. 2006-065321 can be preferably used.

The cationic surfactant is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, alkylimidazolinium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

The surfactant may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the surfactant is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, still more preferably 3 to 15% by mass, and particularly preferably 5 to 10% by mass, based on the total mass of the developer. When the amount is within the above range, the lithographic printing plate is more excellent in scratch contamination resistance, excellent in dispersibility of the development residue, and excellent in ink-receptivity of the obtained lithographic printing plate.

Water-soluble high molecular compound-

The developer can contain a water-soluble polymer compound from the viewpoint of adjusting the viscosity of the developer and protecting the plate surface of the obtained lithographic printing plate.

Examples of the water-soluble polymer compound include water-soluble polymer compounds such as soybean polysaccharides, modified starch, gum arabic, starch essence, cellulose derivatives (e.g., carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.) and modified products thereof, pullulan, polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone, polyacrylamide and acrylamide copolymers, vinyl methyl ether/maleic anhydride copolymers, vinyl acetate/maleic anhydride copolymers, and styrene/maleic anhydride copolymers.

As the soybean polysaccharides, conventionally known soybean polysaccharides can be used, and for example, commercially available soybean polysaccharides having a trade name of Soyafibe (FUJI OIL co., ltd.) can be used in various grades. Soybean polysaccharides having a viscosity of 10 to 100mPa · s in a10 mass% aqueous solution can be preferably used.

The modified starch is preferably a starch represented by the following formula (III). As the starch represented by formula (III), any starch such as corn, potato, tapioca, rice, wheat, and the like can be used. The modification of these starches can be carried out by the following method or the like: decomposing the glucose into 5 to 30 residues per 1 molecule by acid or enzyme, and adding oxypropylene to the alkali.

[ chemical formula 18]

Wherein the etherification degree (substitution degree) is in the range of 0.05 to 1.2 per glucose unit, n represents an integer of 3 to 30, and m represents an integer of 1 to 3.

Among the water-soluble high molecular compounds, particularly preferred are soybean polysaccharides, modified starch, gum arabic, syrup essence, carboxymethyl cellulose, polyvinyl alcohol, and the like.

The water-soluble polymer compound can be used in combination of 2 or more.

When the developer contains a water-soluble polymer compound, the content of the water-soluble polymer compound is preferably 3% by mass or less, and more preferably 1% by mass or less, based on the total mass of the developer. In this manner, the viscosity of the developer is appropriate, and accumulation of development residue and the like on the roller member of the automatic developing machine can be suppressed.

Other additives

The developer used in the present invention may contain, in addition to the above, a wetting agent, an antiseptic agent, a chelate compound, an antifoaming agent, an organic acid, an organic solvent, an inorganic acid, an inorganic salt, and the like.

As the humectant, ethylene glycol, propylene glycol, triethylene glycol, butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, diglycerin, and the like can be preferably used. The humectant can be used alone or in combination of 2 or more. The content of the wetting agent is preferably 0.1 to 5% by mass based on the total mass of the developer.

As the preservative, phenol or a derivative thereof, formaldehyde, an imidazole derivative, sodium dehydroacetate, a 4-isothiazolin-3-one derivative, benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, a benzotriazole derivative, an amidinobuanidine derivative, a quaternary ammonium salt, a pyridine, a quinoline, a guanidine derivative, a diazine, a triazole derivative, an oxazole, an oxazine derivative, a bromonitropropane-1, 3-diol of bromonitroalcohol type, 1-dibromo-1-nitro-2-ethanol, 1-dibromo-1-nitro-2-propanol, and the like can be preferably used.

The amount of the preservative added is an amount that exerts a stabilizing effect on bacteria, molds, yeasts, and the like, and varies depending on the types of bacteria, molds, and yeasts, but is preferably in the range of 0.01 to 4% by mass relative to the total mass of the developer. Further, it is preferable to use 2 or more kinds of preservatives at the same time so as to have an effect on various molds and sterilization.

Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salts thereof, and sodium salts thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetramine hexaacetic acid, potassium salts thereof, sodium salts thereof; hydroxyethylethylenediaminetriacetic acid, its potassium salt, its sodium salt; nitrilotriacetic acid, its sodium salt; 1-hydroxyethane-1, 1-diphosphonic acid, potassium salts thereof, sodium salts thereof; and organic phosphonic acids such as aminotri (methylenephosphonic acid), potassium salts thereof, and sodium salts thereof. The salts of organic amines are effective in replacing the sodium and potassium salts of the chelating agent.

The chelating agent is preferably stably present in the treatment liquid composition and does not hinder printability. The content of the chelating agent is preferably 0.001 to 1.0 mass% based on the total mass of the developer.

As the defoaming agent, a general silicone-based self-emulsifying type, an emulsifying type, a compound having a nonionic HLB (Hydrophilic-Lipophilic Balance) of 5 or less, and the like can be used. Silicone defoamers are preferred.

In addition, silicone-based surfactants are considered to be antifoaming agents.

The content of the defoaming agent is preferably in the range of 0.001 to 1.0% by mass based on the total mass of the developer.

Examples of the organic acid include citric acid, acetic acid, oxalic acid, malonic acid, salicylic acid, octanoic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. The organic acids can also be used in the form of their alkali metal or ammonium salts. The content of the organic acid is preferably 0.01 to 0.5% by mass based on the total mass of the developer.

Examples of the organic solvent include aliphatic hydrocarbons (hexane, heptane, "ISOPAR E, H, G" (esso chemicals co., ltd.), etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated hydrocarbons (dichloromethane, dichloroethane, trichloroethylene, monochlorobenzene, etc.), polar solvents, and the like.

Examples of the polar solvent include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polypropylene glycol, tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, methylphenylcarbinol, n-amyl alcohol, methylpentanol, etc.), ketones (acetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), esters (ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, benzyl acetate, methyl lactate, butyl lactate, ethylene glycol monobutyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol acetate, diethyl phthalate, butyl levulinate, etc.), and others (triethyl phosphate, butyl acetate, etc.), Tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.).

When the organic solvent is not contained in water, it is possible to use a surfactant or the like which is soluble in water, and when the developer contains an organic solvent, the concentration of the solvent in the developer is preferably less than 40% by mass from the viewpoint of safety and flammability.

Examples of the inorganic acid and inorganic salt include phosphoric acid, metaphosphoric acid, monoammonium phosphate, diammonium phosphate, monosodium phosphate, disodium phosphate, monopotassium phosphate, dipotassium phosphate, sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogensulfate, and nickel sulfate. The content of the inorganic salt is preferably 0.01 to 0.5 mass% based on the total mass of the developer.

The developer is prepared by dissolving or dispersing the above-mentioned respective components in water as necessary. The solid content concentration of the developer is preferably 2 to 25% by mass. As the developer, a concentrated solution may be prepared in advance and may be used by diluting with water.

The developer is preferably an aqueous developer.

The developer preferably contains an alcohol compound from the viewpoint of dispersibility of the development residue.

Examples of the alcohol compound include methanol, ethanol, propanol, isopropanol, and benzyl alcohol. Among them, benzyl alcohol is preferred.

The content of the alcohol compound is preferably 0.01 to 5% by mass, more preferably 0.1 to 2% by mass, and particularly preferably 0.2 to 1% by mass, based on the total mass of the developer, from the viewpoint of dispersibility of the developing residue.

(lithographic printing method)

< printing Process >

The lithographic printing method according to the present invention includes a printing step of supplying printing ink on a lithographic printing plate to print a recording medium.

The printing ink is not particularly limited, and various known inks can be used as desired. Further, as the printing ink, oil-based ink or ultraviolet curable ink (UV ink) is preferable, and UV ink is more preferable.

In the printing step, a fountain solution may be supplied as needed.

The printing step may be performed continuously with the on-press developing step without stopping the printing press.

The recording medium is not particularly limited, and a known recording medium can be used as desired.

In the method for producing a lithographic printing plate from the lithographic printing plate precursor according to the present invention and the lithographic printing method according to the present invention, the entire surface of the lithographic printing plate precursor is heated before exposure, during exposure, and during a period from exposure to development, as necessary. Such heating promotes an image forming reaction in the image recording layer, and can provide advantages such as improvement in sensitivity, brush resistance, and stabilization of sensitivity. The heating before development is preferably carried out under mild conditions of 150 ℃ or lower. In this way, problems such as curing of the non-image portion can be prevented. It is preferable to use very strong conditions for heating after development, and the temperature is preferably in the range of 100 to 500 ℃. Within the above range, a sufficient image-strengthening effect is obtained, and problems such as deterioration of the support and thermal decomposition of the image portion can be suppressed.