阅读说明：本技术 喷墨油墨组合物、图像记录方法及图像记录物 (Inkjet ink composition, image recording method, and image recorded matter ) 是由 蒲原一男 于 2019-11-29 设计创作，主要内容包括：本发明提供一种喷墨油墨组合物及其应用,所述喷墨油墨组合物含有：由式(A)表示的单体A；作为包含脂环结构且不包含杂环结构的自由基聚合性单体的单体B；以及作为包含杂环结构的自由基聚合性单体的单体C,单体A、单体B及单体C的总含量相对于组合物的总量为60质量％以上。R～(1)～R～(4)分别独立地表示氢原子或碳原子数1～10的有机基团,n表示1～3的整数。在n为2或3的情况下,两个或三个R～(3)可以相同也可以不同,两个或三个R～(4)可以相同也可以不同。(The present invention provides an inkjet ink composition and its use, the inkjet ink composition comprising: a monomer A represented by the formula (A); a monomer B which is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure; and a monomer C which is a radical polymerizable monomer having a heterocyclic structure, wherein the total content of the monomer A, the monomer B and the monomer C is 60% by mass or more relative to the total amount of the composition. R 1 ～R 4 Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3. In the case where n is 2 or 3,two or three R 3 Two or three R, which may be the same or different 4 May be the same or different.)

1. An inkjet ink composition comprising:

a monomer A as a radical polymerizable monomer represented by the formula (A);

a monomer B which is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure; and

as the monomer C of the radical polymerizable monomer having a heterocyclic structure,

the total content of the monomer A, the monomer B, and the monomer C is 60% by mass or more relative to the total amount of the inkjet ink composition,

in the formula (A), R¹～R⁴Each independently represents a hydrogen atom or a carbon atom number 110, n represents an integer of 1 to 3; in case n is 2 or 3, two or three R³Two or three R, which may be the same or different⁴May be the same or different.

2. The inkjet ink composition according to claim 1, wherein the content of the monomer a is 10% by mass to 30% by mass with respect to the total amount of the inkjet ink composition.

3. The inkjet ink composition according to claim 1 or claim 2, wherein the content of the monomer B is 20% by mass to 40% by mass with respect to the total amount of the inkjet ink composition.

4. The inkjet ink composition according to any one of claims 1 to 3, wherein the content of the monomer C is 20 to 40% by mass with respect to the total amount of the inkjet ink composition.

5. The inkjet ink composition according to any one of claims 1 to 4, wherein the total content of the monomer A and the monomer B is 35% by mass or more relative to the total amount of the inkjet ink composition.

6. The inkjet ink composition according to any one of claims 1 to 5, wherein the content of the monomer A is 15 to 40% by mass with respect to the total content of all radically polymerizable monomers contained in the inkjet ink composition.

7. The inkjet ink composition according to any one of claims 1 to 6, wherein the inkjet ink composition further contains a photopolymerization initiator.

8. The inkjet ink composition of any one of claims 1 to 7, wherein the inkjet ink composition further comprises a colorant.

9. An image recording method comprising the steps of:

a step of applying the inkjet ink composition according to any one of claims 1 to 8 to a substrate by inkjet; and

and irradiating the inkjet ink composition provided on the substrate with active energy rays.

10. An image recorded matter, comprising:

a substrate; and

an image which is a cured product of the inkjet ink composition according to any one of claims 1 to 8 disposed on the substrate.

Technical Field

The present disclosure relates to an inkjet ink composition, an image recording method, and an image recorded matter.

Background

Conventionally, various studies have been made on inks used for image recording.

For example, patent document 1 discloses an ink jet printing ink containing N-vinyl oxazolidone as an ink jet printing ink having high reactivity and low viscosity in radiation curing.

Patent document 2 discloses a method of recording an image on a polypropylene substrate or a corona-treated polystyrene substrate by an ink jet method. Patent document 2 discloses, as an inkjet ink used in this method, an inkjet ink containing: isobornyl acrylate in an amount of 20% by mass or more based on the total amount of the ink; an N-vinylamide monomer, an N-acrylamide monomer, and/or an N-vinylcarbamate in a total content of 15 to 30 mass% relative to the total amount of the ink; a resin; a photopolymerization initiator; and optionally a colorant.

Prior art documents

Patent document

Patent document 1: japanese patent No. 6316428

Patent document 2: international publication No. 2018/146495

Disclosure of Invention

Technical problem to be solved by the invention

However, the inkjet ink composition is sometimes required to be curable to light irradiation (hereinafter, also simply referred to as "curability").

Furthermore, it is sometimes required to suppress the stickiness of the surface of an image recorded using the inkjet ink composition in a high-temperature environment (for example, in an environment of 40 ℃).

Further, the inkjet ink composition may be required to have excellent ejection properties (hereinafter, also simply referred to as "ejection properties") for ejection from an inkjet head in addition to satisfying the above-described requirements.

An object of one aspect of the present disclosure is to provide an inkjet ink composition that can suppress stickiness of a surface of a recorded image in a high-temperature environment (for example, in an environment of 40 ℃), and is excellent in curability and ejection property, an image recording method using the inkjet ink composition, and an image recorded matter including an image as a cured product of the inkjet ink composition.

Means for solving the technical problem

Specific means for solving the problem include the following.

<1> an inkjet ink composition, wherein,

comprises the following components:

a monomer A as a radical polymerizable monomer represented by the formula (A);

a monomer B which is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure; and

as the monomer C of the radical polymerizable monomer having a heterocyclic structure,

the total content of the monomer a, the monomer B, and the monomer C is 60% by mass or more with respect to the total amount of the inkjet ink composition.

[ chemical formula 1]

In the formula (A), R¹～R⁴Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3. In case n is 2 or 3, two or three R³Two or three R, which may be the same or different⁴May be the same or different.

<2> the inkjet ink composition according to <1>, wherein the content of the monomer a is 10% by mass to 30% by mass based on the total amount of the inkjet ink composition.

<3> the inkjet ink composition according to <1> or <2>, wherein the content of the monomer B is 20% by mass or more and 40% by mass or less with respect to the total amount of the inkjet ink composition.

<4> the inkjet ink composition according to any one of <1> to <3>, wherein the content of the monomer C is 20% by mass to 40% by mass with respect to the total amount of the inkjet ink composition.

<5> the inkjet ink composition according to any one of <1> to <4>, wherein the total content of the monomer A and the monomer B is 35% by mass or more based on the total amount of the inkjet ink composition.

<6> the inkjet ink composition according to any one of <1> to <5>, wherein the content of the monomer a is 15% by mass to 40% by mass based on the total content of all radically polymerizable monomers contained in the inkjet ink composition.

<7> the inkjet ink composition according to any one of <1> to <6>, which further contains a photopolymerization initiator.

<8> the inkjet ink composition according to any one of <1> to <7>, which further contains a colorant.

<9> an image recording method, comprising:

a step of applying the inkjet ink composition according to any one of <1> to <7> to a substrate by inkjet; and

and irradiating the inkjet ink composition provided on the substrate with active energy rays.

<10> an image recorded matter, comprising:

a substrate; and

an image which is a cured product of the inkjet ink composition according to any one of <1> to <7> disposed on a substrate.

Effects of the invention

According to one aspect of the present disclosure, there is provided an inkjet ink composition which can suppress stickiness of a surface of a recorded image in a high-temperature environment (for example, in an environment of 40 ℃), and is excellent in curability and ejection property, an image recording method using the inkjet ink composition, and an image recorded matter including an image as a cured product of the inkjet ink composition.

Detailed Description

In the present disclosure, the numerical range expressed by the term "to" refers to a range including numerical values before and after the term "to" as a lower limit value and an upper limit value.

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

In the numerical ranges described in the present disclosure, the upper limit or the lower limit described in a certain numerical range may be replaced with the upper limit or the lower limit described in other numerical ranges, or may be replaced with the values shown in the examples.

In the present disclosure, the term "step" includes not only an independent step, but also a step that can achieve the intended purpose if it cannot be clearly distinguished from other steps.

In the present disclosure, a combination of preferred embodiments is a more preferred embodiment.

In the present disclosure, "light" is a concept including active energy rays such as so-called γ rays, β rays, electron beams, ultraviolet rays, visible rays, and the like.

In the present disclosure, ultraviolet light is also sometimes referred to as "uv (ultra violet) light".

In the present disclosure, "(meth) acrylic acid" is a concept including both acrylic acid and methacrylic acid, "(meth) acrylate" is a concept including both acrylate and methacrylate, "(meth) acrylamide" is a concept including both acrylamide and methacrylamide, and "(meth) acryl" is a concept including both acryl and methacrylamido groups.

In the present disclosure, "image" refers to the entire film formed using the inkjet ink composition, and "recording of image" refer to film formation and film formation, respectively. Therefore, the "image" in the present disclosure is not limited to a film having a color, and may be, for example, a transparent film. Here, the term "transparent" as used herein means that the film has a transmittance of 80% or more (preferably 90% or more) for visible light having a wavelength of 400nm to 700 nm.

In addition, the concept of "image" in the present disclosure also includes a solid image (solid image).

[ ink jet ink composition ]

The inkjet ink composition of the present disclosure (hereinafter, also simply referred to as "ink") is an ink containing: a monomer A as a radical polymerizable monomer represented by the formula (A); a monomer B which is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure; and a monomer C which is a radical polymerizable monomer having a heterocyclic structure, wherein the total content of the monomer A, the monomer B and the monomer C is 60% by mass or more relative to the total amount of the ink.

[ chemical formula 2]

In the formula (A), R¹～R⁴Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3. In case n is 2 or 3, two or three R³Two or three R, which may be the same or different⁴May be the same or different.

The ink according to the present disclosure can suppress stickiness of the surface of a recorded image in a high-temperature environment (e.g., an environment of 40 ℃ C. the same applies hereinafter), and is excellent in curability (i.e., curability against light irradiation) and ejection property (i.e., ejection property of ejection from an inkjet head).

Here, "capable of suppressing the stickiness of the surface of a recorded image in a high-temperature environment" means that an image in which the stickiness of the surface in a high-temperature environment is suppressed can be recorded.

In the present disclosure, the tackiness of the surface of a recorded image in a high-temperature environment is sometimes simply referred to as "surface tackiness", and the performance of an ink capable of suppressing the tackiness of the surface of a recorded image in a high-temperature environment is sometimes referred to as "surface tackiness suppressing property".

In the present disclosure, the stickiness of the surface refers to the stickiness of the surface of an image recorded by ink curing (i.e., the cured ink) when the image is left in a high-temperature environment.

In the present disclosure, the curability means the curability of the ink at the stage of recording an image by curing the ink (i.e., the curing speed of the ink).

Therefore, the surface tack inhibition property and the curability are mutually related properties, but are not completely consistent properties.

The reason why the above-described effects are obtained by the ink of the present disclosure is not clear, and can be roughly estimated as follows.

In the ink of the present disclosure, the monomer a is considered to contribute mainly to curability.

In the ink of the present disclosure, the monomer B mainly contributes to surface tackiness inhibition (i.e., a property of inhibiting surface tackiness of a recorded image) and curability, and particularly, the effect of the monomer B on the surface tackiness inhibition is considered to be large.

In the ink of the present disclosure, the monomer C is considered to contribute mainly to the ejection property and the curability, and particularly, the effect on the ejection property is considered to be large.

In the ink of the present disclosure, the total content of the monomer a, the monomer B, and the monomer C is 60 mass% or more with respect to the total amount of the ink, and the total content is considered to contribute to any one of the curability, the surface tack inhibiting property, and the ejection property.

It is presumed that these features are combined in the ink of the present disclosure, thereby exhibiting the above-described effects.

Hereinafter, each component that can be contained in the ink of the present disclosure will be described.

< monomer A >

The ink of the present disclosure contains at least one monomer a as a radical polymerizable monomer represented by the following formula (a).

[ chemical formula 3]

In the formula (A), R¹～R⁴Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3. In case n is 2 or 3, two or three R³Two or three R, which may be the same or different⁴May be the same or different.

In the formula (A), R¹～R⁴Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms.

As R¹～R⁴The number of carbon atoms of the organic group represented by (a) is preferably 1 to 6, more preferably 1 or 2, and still more preferably 1.

As R¹～R⁴The organic group represented by (a) is preferably an alkyl group, an alkenyl group, an aryl group or an aralkyl group, more preferably an alkyl group or an aryl group, and still more preferably an alkyl group.

As the formula (A),

preferably R¹And R³Each independently represents a hydrogen atom or an organic group having 1 to 10 carbon atoms and R²And R⁴All are schemes of hydrogen atoms.

Further preferred is R¹R is a hydrogen atom or an organic group having 1 to 10 carbon atoms²～R⁴All are schemes of hydrogen atoms.

In these embodiments, the preferable range of the organic group having 1 to 10 carbon atoms is also as described above.

In the formula (A), n represents an integer of 1 to 3. In case n is 2 or 3, two or three R³Two or three R, which may be the same or different⁴May be the same or different.

In the formula (a), n is preferably 1 or 2, and more preferably 1.

Specific examples of the radical polymerizable monomer represented by the formula (a) are listed below, but the radical polymerizable monomer represented by the formula (a) is not limited to the specific examples below.

[ chemical formula 4]

In the above-described specific examples,

the compound (a-1) is N-vinyl oxazolidone (NVO for short),

the compound (a-2) is N-vinyl-5-methyl oxazolidinone (NVMO for short).

The content of the monomer A is not particularly limited.

From the viewpoint of further improving curability, the content of the monomer a is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and still more preferably 15 to 25% by mass, based on the total amount of the ink.

From the viewpoint of further improving curability, the content of the monomer a is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and still more preferably 15 to 35% by mass, based on the total content of all the radical polymerizable monomers contained in the ink.

From the viewpoint of further improving curability, the content of the monomer a is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and still more preferably 15 to 35% by mass, based on the total content of the monomer a, the monomer B, and the monomer C.

< monomer B >

The ink of the present disclosure contains at least one monomer B as a radical polymerizable monomer containing an alicyclic structure and not containing a heterocyclic structure.

Monomer B comprises at least one alicyclic structure.

Examples of the alicyclic structure include: monocyclic structures, fused ring structures, bridged ring structures, spiro ring structures, and the like.

The alicyclic structure preferably has 3 to 20 carbon atoms, preferably 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.

The monomer B preferably contains a vinyl group, an allyl group, or a (meth) acryloyl group as a radical polymerizable group, and more preferably contains a (meth) acryloyl group.

The monomer B is preferably a monofunctional or difunctional radically polymerizable monomer, and more preferably a monofunctional radically polymerizable monomer.

Here, the monofunctional radical polymerizable monomer means a radical polymerizable monomer including one radical polymerizable group, and the difunctional radical polymerizable monomer means a radical polymerizable monomer including two radical polymerizable groups.

The molecular weight of the monomer B is preferably 1000 or less, more preferably 500 or less, and still more preferably 300 or less.

Examples of the monomer B include:

cyclohexyl (meth) acrylate,

Isobornyl (meth) acrylate,

2-methyladamantan-2-yl (meth) acrylate,

2-ethyl adamantan-2-yl (meth) acrylate,

3-hydroxy-1- (meth) acryloyloxyadamantane,

Dicyclopentyl (meth) acrylate,

Dicyclopentenyloxyethyl (meth) acrylate,

Dicyclopentenyl (meth) acrylate,

Dicyclopentenyloxyethyl (meth) acrylate, and the like.

The content of the monomer B is not particularly limited.

The content of the monomer B is preferably 10 to 50% by mass, and more preferably 20 to 40% by mass, based on the total amount of the ink.

When the content of the monomer B is 10% by mass or more based on the total amount of the ink, the surface tackiness inhibitory property (i.e., the property of inhibiting the surface tackiness of a recorded image) and the curability are further improved.

When the content of the monomer B is 50% by mass or less based on the total amount of the ink, the ejection property is further improved.

The content of the monomer B is preferably 10 to 60% by mass, and more preferably 20 to 50% by mass, based on the total content of all the radically polymerizable monomers contained in the ink.

When the content of the monomer B is 10% by mass or more based on the total content of all the radically polymerizable monomers contained in the ink, the surface tackiness inhibitory property and the curability are further improved.

When the content of the monomer B is 60 mass% or less with respect to the total content of all the radical polymerizable monomers contained in the ink, the ejection property is further improved.

The content of the monomer B is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, based on the total content of the monomer a, the monomer B and the monomer C.

When the content of the monomer B is 10% by mass or more based on the total content of the monomer a, the monomer B, and the monomer C, the surface tackiness inhibitory property and the curability are further improved.

When the content of the monomer B is 60% by mass or less based on the total content of the monomer a, the monomer B, and the monomer C, the ejection property is further improved.

The total content of the monomer a and the monomer B is preferably 35% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more, based on the total amount of the ink.

When the total content of the monomer a and the monomer B is 35% by mass or more based on the total amount of the ink, the surface tackiness inhibitory property and the curability are further improved.

The upper limit of the total content of the monomer a and the monomer B with respect to the total amount of the ink is not particularly limited. The upper limit is preferably 80 mass%, more preferably 70 mass%, from the viewpoint of ejection property.

The total content of the monomer a and the monomer B is preferably 45 mass% or more, more preferably 50 mass% or more, and still more preferably 55 mass% or more, based on the total content of all the radically polymerizable monomers contained in the ink.

When the total content of the monomer a and the monomer B is 45 mass% or more with respect to the total content of all the radical polymerizable monomers contained in the ink, the surface tackiness inhibitory property and the curability are further improved.

The upper limit of the total content of the monomer a and the monomer B with respect to the total content of all the radically polymerizable monomers contained in the ink is not particularly limited. The upper limit is preferably 80 mass%, more preferably 70 mass%, from the viewpoint of ejection property.

The total content of the monomer a and the monomer B is preferably 45 mass% or more, more preferably 50 mass% or more, and still more preferably 55 mass% or more, based on the total content of the monomer a, the monomer B, and the monomer C.

When the total content of the monomer a and the monomer B is 45 mass% or more with respect to the total content of the monomer a, the monomer B, and the monomer C, the surface tackiness inhibitory property and the curability are further improved.

The upper limit of the total content of the monomer a and the monomer B to the total content of the monomer a, the monomer B, and the monomer C is not particularly limited. The upper limit is preferably 80 mass%, more preferably 70 mass%, from the viewpoint of ejection property.

< monomer C >

The ink of the present disclosure contains at least one monomer C as a radical polymerizable monomer containing a heterocyclic structure.

Monomer C contains at least one heterocyclic structure.

The hetero atom contained in the heterocyclic structure is preferably an oxygen atom, a sulfur atom, or a nitrogen atom, more preferably an oxygen atom or a nitrogen atom, and still more preferably an oxygen atom.

The number of hetero atoms contained in one heterocyclic structure is preferably 1 to 3, more preferably 1 or 2.

The number of carbon atoms contained in one heterocyclic structure is preferably 3 to 20, more preferably 3 to 12, and further preferably 3 to 5.

As the heterocyclic structure, there can be mentioned: monocyclic structures, fused ring structures, bridged ring structures, spiro ring structures, and the like.

The fused ring structure, bridged ring structure and spiro ring structure may each include a heterocyclic ring and an aliphatic ring and/or an aromatic ring.

The heterocyclic structure is preferably a monocyclic heterocyclic structure having 5-or 6-membered rings.

In addition, the monomer C contains at least one heterocyclic structure, and may further contain at least one alicyclic structure.

Examples and preferred embodiments of the alicyclic structure that may be contained in the monomer C are the same as those of the alicyclic structure contained in the monomer B described above, respectively.

The monomer C preferably contains a vinyl group, an allyl group, or a (meth) acryloyl group as a radical polymerizable group, and more preferably contains a (meth) acryloyl group.

The monomer C is preferably a monofunctional or difunctional radically polymerizable monomer, and more preferably a monofunctional radically polymerizable monomer.

Here, the monofunctional radical polymerizable monomer means a radical polymerizable monomer including one radical polymerizable group, and the difunctional radical polymerizable monomer means a radical polymerizable monomer including two radical polymerizable groups.

The molecular weight of the monomer C is preferably 1000 or less, more preferably 500 or less, and still more preferably 300 or less.

Examples of the monomer C include:

cyclic trimethylolpropane formal (meth) acrylate,

(meth) acryloyl morpholine,

(2-methyl-2-ethyl-1, 3-dioxolan-4-yl) methyl (meth) acrylate,

Tetrahydrofurfuryl (meth) acrylate,

Alkoxylated tetrahydrofurfuryl (meth) acrylate,

Tetramethylpiperidine (meth) acrylate,

Pentamethylpiperidine (meth) acrylate, and the like.

The content of the monomer C is not particularly limited.

The content of the monomer C is preferably 10 to 50% by mass, and more preferably 20 to 40% by mass, based on the total amount of the ink.

When the content of the monomer C is 10% by mass or more based on the total amount of the ink, the ejection property is further improved.

When the content of the monomer C is 50% by mass or less based on the total amount of the ink, the surface tackiness inhibitory property is further improved.

The content of the monomer C is preferably 10 to 60% by mass, and more preferably 20 to 50% by mass, based on the total content of all the radically polymerizable monomers contained in the ink.

When the content of the monomer C is 10% by mass or more based on the total content of all the radical polymerizable monomers contained in the ink, the ejection property is further improved.

When the content of the monomer C is 60% by mass or less based on the total content of all the radically polymerizable monomers contained in the ink, the surface tackiness inhibitory property is further improved.

The content of the monomer C is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, based on the total content of the monomer a, the monomer B, and the monomer C.

When the content of the monomer C is 10% by mass or more based on the total content of the monomer a, the monomer B, and the monomer C, the ejection property is further improved.

When the content of the monomer C is 60% by mass or less based on the total content of the monomer a, the monomer B, and the monomer C, the surface tackiness inhibitory property is further improved.

In the ink of the present disclosure, the total content of the monomer a, the monomer B, and the monomer C is 60 mass% or more with respect to the total amount of the ink.

This improves curability and ejection property.

The total content of the monomer a, the monomer B, and the monomer C is preferably 65% by mass or more with respect to the total amount of the ink.

The upper limit of the total content of the monomer a, the monomer B and the monomer C with respect to the total amount of the ink is not particularly limited.

The upper limit of the total content of the monomer a, the monomer B, and the monomer C relative to the total amount of the ink may be, for example, 95 mass% or 90 mass%.

In addition, the total content of the monomer a, the monomer B, and the monomer C is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total content of all the radically polymerizable monomers contained in the ink, from the viewpoint of more effectively exerting the effect produced by the ink of the present disclosure.

The total content of the monomer a, the monomer B, and the monomer C may be 100% by mass based on the total content of all the radically polymerizable monomers contained in the ink.

< other radically polymerizable monomer >

The ink of the present disclosure may further contain other radically polymerizable monomers other than the above-mentioned monomers.

As other radically polymerizable monomers, known radically polymerizable monomers can be used, and examples thereof include: (meth) acrylate compounds, (meth) acrylamide compounds, vinyl ether compounds, allyl compounds, N-vinyl compounds, unsaturated carboxylic acids, and the like.

As other radically polymerizable monomers, there can be used radically polymerizable monomers described in Japanese patent application laid-open No. 2009-221414, radically polymerizable compounds described in Japanese patent application laid-open No. 2009-209289, ethylenically unsaturated compounds described in Japanese patent application laid-open No. 2009-191183, and the like.

The other radical polymerizable monomer is preferably a (meth) acrylate compound.

The molecular weight of the other radical polymerizable monomer is preferably 80 to 1,000, more preferably 80 to 800, and further preferably 80 to 500.

The other radical polymerizable monomer may be a monofunctional radical polymerizable monomer or a bifunctional or higher radical polymerizable monomer.

Specific examples of other radically polymerizable monomers include:

a monofunctional (meth) acrylate compound such as an alkyl (meth) acrylate compound having an alkyl group having 1 to 20 carbon atoms;

difunctional (meth) acrylate compounds such as 1, 6-hexanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and propoxylated (2) neopentyl glycol diacrylate;

trifunctional (meth) acrylate compounds such as trimethylolpropane tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, and Ethylene Oxide (EO) -modified trimethylolpropane tri (meth) acrylate.

Examples of other radically polymerizable monomers include: unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid, salts thereof, anhydrides having an ethylenically unsaturated group, acrylonitrile, styrene, and various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

More specifically, it is also possible to use: shanxi jin Sandito "Manual of crosslinking agent" (1981, Dacheng company); "UV. EB curing Manual (materials) by Kangteng vision (1985, high molecular journal); the RadTech research institute encodes "application and market of UV EB curing technology" page 79 (published by CMC, Inc. 1989); commercially available or commercially known radically polymerizable monomers, oligomers, and polymers described in "handbook of polyester resins" (1988, journal of the Industrial News Co., Ltd.) and the like, Rongshan.

The ink of the present disclosure may further contain N-vinylcaprolactam, which is widely used in the field of photocurable inks, as another radically polymerizable monomer.

Among these, the monomer a in the ink of the present disclosure can function as a substitute for N-vinylcaprolactam.

Thus, the inks of the present disclosure may also be free of N-vinyl caprolactam. In addition, even in the case where the ink of the present disclosure contains N-vinylcaprolactam, the content of N-vinylcaprolactam can be reduced.

The content of N-vinylcaprolactam in the ink of the present disclosure may be 10 mass% or less, may be 5 mass% or less, and may be 1 mass% or less with respect to the total amount of the ink.

The ink of the present disclosure may further contain a trifunctional or higher radically polymerizable monomer as another radically polymerizable monomer.

Among these, the content of the trifunctional or higher radically polymerizable monomer in the ink of the present disclosure is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 1% by mass or less, and even more preferably 0% by mass, relative to the total amount of the ink, from the viewpoints of the ejection property of the ink, the flexibility of an image, the glossiness of an image, and the like (that is, the ink of the present disclosure does not contain the trifunctional or higher radically polymerizable monomer).

In the ink of the present disclosure, the total content of the monofunctional radical polymerizable monomer and the difunctional radical polymerizable monomer is preferably 60% by mass or more, and more preferably 65% by mass or more, based on the total amount of the ink, from the viewpoint of the ejection property of the ink.

The upper limit of the total content of the monofunctional radically polymerizable monomer and the difunctional radically polymerizable monomer is not particularly limited, and examples of the upper limit include: 100 mass%, 95 mass%, 90 mass%, etc.

In the ink of the present disclosure, the ratio of the monofunctional radical polymerizable monomer to the total radical polymerizable monomers contained in the ink is preferably 60% by mass or more, and more preferably 65% by mass or more.

The upper limit of the ratio of the monofunctional radical polymerizable monomer to the total radical polymerizable monomers contained in the ink is not particularly limited, and examples of the upper limit include: 100 mass%, 95 mass%, 90 mass%, etc.

< photopolymerization initiator >

The ink of the present disclosure preferably contains at least one photopolymerization initiator.

As the photopolymerization initiator, a known photopolymerization initiator that absorbs light (i.e., active energy rays) to generate radicals as polymerization initiating species can be used.

Preferred photopolymerization initiators include: (a) carbonyl compounds such as aromatic ketones, (b) acylphosphine oxide compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thio compounds, (f) hexaarylbiimidazole compounds, (g) ketoxime ester compounds, (h) borate ester compounds, (i) azinium compounds, (j) metallocene compounds, (k) active ester compounds, (l) compounds having a carbon-halogen bond, (m) alkylamine compounds, and the like.

These photopolymerization initiators may be used singly or in combination of two or more kinds of the compounds (a) to (m).

The photopolymerization initiators (a), (b) and (e) are more preferable.

Preferable examples of (a) the carbonyl compound, (b) the acylphosphine oxide compound, and (e) the thio compound include: examples of the "chemical CURING IN POLYMER SCIENCE AND TECHNOLOGY", J.P.FOASSIER, J.F.RABEK (1993), and compounds having a benzophenone skeleton or a thioxanthone skeleton described IN pp.77 to 117.

More preferable examples include: an α -mercaptobenzophenone compound described in Japanese patent publication No. 47-6416, a benzoin ether compound described in Japanese patent publication No. 47-3981, an α -substituted benzoin compound described in Japanese patent publication No. 47-22326, a benzoin derivative described in Japanese patent publication No. 47-23664, an aroylphosphonate ester described in Japanese patent publication No. 57-30704, a dialkoxybenzophenone described in Japanese patent publication No. 60-26483, a benzoin ether described in Japanese patent publication No. 60-26403, a benzoin ether described in Japanese patent publication No. 62-81345, a Japanese patent publication No. 1-34242, a pamphlet of U.S. Pat. No. 4,318,791, an α -aminobenzophenone described in European patent publication No. 0284561A1, a p-bis (dimethylaminobenzoyl) benzophenone described in Japanese patent publication No. 2-211452, a benzoin derivative described in Japanese patent publication No. 47-23664, a benzoin ether described in Japanese patent publication No. 57-30704, a dialkoxybenzophenone described in Japanese patent publication No. 60-26483, a benzoin ether described in Japanese patent publication No. 62-34345, a, Examples of the sulfur-substituted aromatic ketone include a sulfur-substituted aromatic ketone described in JP-A-61-194062, an acylphosphine sulfide described in JP-B-2-9597, an acylphosphine described in JP-B-2-9596, a thioxanthone described in JP-B-63-61950, and a coumarin described in JP-B-59-42864.

Further, the polymerization initiators described in Japanese patent application laid-open Nos. 2008-105379 and 2009-114290 are also preferable.

Among these photopolymerization initiators, (a) a carbonyl compound or (b) an acylphosphine oxide compound is more preferable, and specific examples thereof include: bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide (e.g., IRGACURE (registered trademark) 819 manufactured by BASF corporation), 2- (dimethylamine) -1- (4-morpholinophenyl) -2-benzyl-1-butanone (e.g., IRGACURE (registered trademark) 369 manufactured by BASF corporation), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (e.g., IRGACURE (registered trademark) 907 manufactured by BASF corporation), 1-hydroxy-cyclohexyl-phenyl-ketone (for example, IRGACURE (registered trademark) 184 manufactured by BASF corporation), 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide (for example, DAROCUR (registered trademark) TPO, LUCIRIN (registered trademark) TPO (both manufactured by BASF corporation)), and the like.

Among them, from the viewpoint of improving sensitivity and suitability for LED light, the photopolymerization initiator is preferably (b) an acylphosphine oxide compound, more preferably a monoacylphosphine oxide compound (particularly preferably 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide).

When the ink of the present disclosure contains a photopolymerization initiator, the content of the photopolymerization initiator is preferably 1.0 to 25.0% by mass, more preferably 2.0 to 20.0% by mass, and still more preferably 3.0 to 15.0% by mass, based on the total amount of the ink.

< sensitizer >

The inks of the present disclosure may contain at least one sensitizer.

Here, the sensitizer is a substance that absorbs a specific active energy ray and becomes an electron excited state. The sensitizer after being brought into an electron excited state comes into contact with the photopolymerization initiator to cause effects such as electron transfer, energy transfer, heat generation, and the like. Thereby promoting chemical changes of the photopolymerization initiator, i.e., decomposition, generation of radicals, acids or bases, and the like.

Examples of the sensitizer include: ethyl 4- (dimethylamino) benzoate (EDB), anthraquinone, 3-acylcoumarin derivatives, triphenyl, styryl ketone, 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine, erythrosine, and the like.

Further, as the sensitizer, a compound represented by the general formula (I) described in Japanese patent application laid-open No. 2010-24276 or a compound represented by the general formula (I) described in Japanese patent application laid-open No. 6-107718 can be suitably used.

Among the above, as the sensitizer, at least one selected from the group consisting of thioxanthone, isopropylthioxanthone, ethyl 4- (dimethylamino) benzoate, and benzophenone is preferable from the viewpoints of adaptability to LED light and reactivity with a photopolymerization initiator.

When the ink of the present disclosure contains a sensitizer, the content of the sensitizer is preferably 0.5 to 10% by mass, more preferably 1.0 to 7.0% by mass, and particularly preferably 2.0 to 6.0% by mass.

< surfactant >

The inks of the present disclosure may contain at least one surfactant.

As the surfactant, there may be mentioned: the surfactant described in each of Japanese patent application laid-open Nos. 62-173463 and 62-183457. Examples thereof include: anionic surfactants such as dialkyl sulfosuccinates, alkylnaphthalenesulfonates, and fatty acid salts, nonionic surfactants such as silicones including polyoxyethylene alkyl ethers, polyoxyethylene alkylallyl ethers, acetylene glycol, polyoxyethylene-polyoxypropylene block copolymers, and modified polydimethylsiloxanes, cationic surfactants such as alkylamine salts and quaternary ammonium salts, and betaine surfactants such as carbonylbetaines and sulfobetaines.

Instead of the surfactant, an organic fluorine compound containing no polymerizable group may be used. The organofluorine compound is preferably hydrophobic. Examples of the organic fluorine compound include a fluorine-containing surfactant, an oily fluorine-containing compound (e.g., fluorine oil), and a solid fluorine compound resin (e.g., tetrafluoroethylene resin), and the compounds described in Japanese patent application publication No. 57-9053 (col. 8-17) and Japanese patent application publication No. 62-135826 are listed.

When the ink of the present disclosure contains a surfactant, the content of the surfactant is preferably 0.001 to 5.0% by mass, more preferably 0.05 to 3.0% by mass, and particularly preferably 0.05 to 2.0% by mass, based on the total amount of the ink.

< polymerization inhibitor >

The inks of the present disclosure may contain at least one polymerization inhibitor.

As the polymerization inhibitor, there may be mentioned: p-methoxyphenol, quinones (e.g., hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazine, catechol, alkylphenols (e.g., dibutylhydroxytoluene (BHT), etc.), alkylbisphenols, zinc dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionate, mercaptobenzimidazole, phosphites, 2,6, 6-tetramethylpiperidin-1-oxyl (TEMPO), 2,6, 6-tetramethyl-4-hydroxypiperidin-1-oxyl (TEMPOL), tris (N-nitroso-N-phenylhydroxylamine) aluminum salt (also known as cupferrol Al), and the like.

Among them, at least one selected from the group consisting of p-methoxyphenol, catechol, quinones, alkylphenols, TEMPO, TEMPOL, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salt is preferable, and at least one selected from the group consisting of p-methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salt is more preferable.

When the ink of the present disclosure contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.01 to 2.0% by mass, more preferably 0.02 to 1.0% by mass, and particularly preferably 0.03 to 0.5% by mass, based on the total amount of the ink.

< resin >

The inks of the present disclosure may contain at least one resin.

As the resin, a resin containing no polymerizable group is preferable.

Examples of the resin include: epoxy resins, vinyl chloride resins, vinyl acetate resins, polyesters, (meth) acrylic resins, chlorinated polyolefins, polyketones, and the like.

Commercially available vinyl chloride-based resins include: UCAR solution vinyl resins VYHD, VYHH, VMCA, VROH and VYLF-X manufactured by Dow chemical; solvent-type resins CL, CNL, C5R, TA5R manufactured by Nissan scientific industry; VINNOL (registered trademark) manufactured by Wacker corporation, E15/40, E15/45, H14/36, H15/42, H15/50, H11/59, H40/43, H40/50, H40/55, H40/60, H15/45M, E15/45M, E15/40A, and the like.

Examples of the (meth) acrylic resin include: copolymers of methyl methacrylate and n-butyl methacrylate.

As commercially available products of (meth) acrylic resins, there are exemplified: elvacite 2013 (copolymer of methyl methacrylate and n-butyl methacrylate, Mw 34000), Elvacite 2014 (copolymer of methyl methacrylate and n-butyl methacrylate, Mw 119000), Elvacite 4099 (copolymer of methyl methacrylate and n-butyl methacrylate, Mw 15000) from Lucite International; and DIANAL (registered trademark) BR-113 (butyl methacrylate resin, Mw 30000) by mitsubishi chemical corporation, and the like.

As the (meth) acrylic resin, a resin described as "specific resin" in international publication No. 2017/033984 may be used.

Further, as a commercially available product of polyester, polyester resin ("TEGO (registered trademark) addbond LTH"; Mw 3000) from japan ltd, etc. can be cited.

Examples of commercially available chlorinated polyolefins include SUPERCHLON (registered trademark) 814HS of Nippon paper-making Co., Ltd.

Commercially available polyketones include TEGO (registered trademark) VARIPLUS AP, CA, SK, etc. from the winning companies.

The weight average molecular weight (Mw) of the resin is preferably 3000 to 200000, more preferably 5000 to 200000, still more preferably 10000 to 150000, still more preferably 10000 to 100000, and particularly preferably 10000 to 50000.

In the present disclosure, the weight average molecular weight (Mw) is a value measured by Gel Permeation Chromatography (GPC).

Measurement by Gel Permeation Chromatography (GPC) HLC (registered trademark) -8020GPC (Toso Cao, Inc.) was used as a measurement apparatus, three TSKgel (registered trademark) Super Multipore HZ-H (4.6 mmID. times.15 cm, Toso Cao, Inc.) columns were used as chromatography columns, and THF (tetrahydrofuran) was used as an eluent. Further, as the measurement conditions, the sample concentration was 0.45 mass%, the flow rate was 0.35ml/min, the sample amount was 10. mu.L, and the measurement temperature was 40 ℃ and the measurement was performed using an RI detector.

The calibration curve was prepared from "standard TSK standard, polystyrene" of Tosoh corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene" were prepared as 8 samples.

When the ink contains a resin, the content of the resin is preferably 1 to 10% by mass, more preferably 1.5 to 10% by mass, and particularly preferably 2 to 6% by mass, based on the total amount of the ink.

< Water >

The inks of the present disclosure may also contain small amounts of water.

Specifically, the content of water is preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less, relative to the total amount of the ink of the present disclosure.

The ink of the present disclosure is preferably a non-aqueous ink containing substantially no water.

< coloring agent >

The inks of the present disclosure may also contain at least one colorant.

The colorant is not particularly limited, and can be arbitrarily selected from known coloring materials such as pigments, water-soluble dyes, and disperse dyes. Among them, pigments are more preferable in terms of excellent weather resistance and rich color reproducibility.

The pigment is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include known organic pigments and inorganic pigments, and further include: resin particles dyed with a dye, commercially available pigment dispersions, or surface-treated pigments [ for example, pigments obtained by dispersing a pigment in a dispersion medium (for example, a radical polymerizable monomer, an organic solvent, or the like), and pigments obtained by treating the surface of a pigment with a resin, a pigment derivative, or the like ].

Examples of the organic pigment and the inorganic pigment include: yellow pigment, red pigment, magenta pigment, blue pigment, cyan pigment, green pigment, orange pigment, violet pigment, brown pigment, black pigment, white pigment, and the like.

In the case where the ink of the present disclosure uses a pigment as a colorant, a pigment dispersant may be contained as needed.

As the colorant such as a pigment and the pigment dispersant, publicly known documents such as paragraphs 0152 to 0158 of Japanese patent application laid-open No. 2011-225848 and paragraphs 0132 to 0149 of Japanese patent application laid-open No. 2009-209352 can be appropriately referred to.

When the ink of the present disclosure contains a colorant, the content of the colorant is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass, with respect to the total amount of the ink.

On the other hand, the ink of the present disclosure may be an ink containing substantially no colorant (so-called clear ink).

Here, the term "substantially not containing a colorant" means that the content of the colorant is less than 0.1% by mass relative to the total amount of the ink.

< other ingredients >

The ink of the present disclosure may further contain other components than those described above.

As other components, there may be mentioned: ultraviolet absorbers, co-sensitizers, antioxidants, discoloration inhibitors, conductive salts, and the like.

For other components, known documents such as japanese patent application laid-open publication No. 2011-225848 and japanese patent application laid-open publication No. 2009-209352 can be referred to as appropriate.

< preferable physical Properties of ink >

The viscosity of the ink of the present disclosure is not particularly limited.

The ink of the present disclosure preferably has a viscosity of 10 to 50 mPas at 25 ℃, more preferably 10 to 30 mPas, and still more preferably 10 to 25 mPas. The viscosity of the ink can be adjusted by adjusting the composition ratio of each component contained therein, for example.

The viscosity referred to herein is measured using a viscometer: a value measured by VISCOMETER RE-85L (manufactured by Toyobo industries, Ltd.).

If the viscosity of the ink is within the above-described preferred range, the ejection property can be further improved.

The surface tension of the ink of the present disclosure is not particularly limited.

The surface tension of the ink of the present disclosure at 30 ℃ is preferably 20mN/m to 30mN/m, and more preferably 23mN/m to 28 mN/m. When images are recorded on various substrates such as polyolefin, PET, coated paper, and non-coated paper, the amount of the ink is preferably 30mN/m or less in terms of wettability, and 20mN/m or more in terms of bleed-out suppression and permeability.

The surface tension referred to herein is a value measured by using a surface tensiometer DY-700 (manufactured by synghonial chemical Co., Ltd.).

[ image recording method ]

The disclosed image recording method comprises the following steps: applying the ink of the present disclosure to a substrate by an inkjet method (hereinafter, also referred to as "applying step"); and irradiation of the ink applied to the substrate with active energy rays (i.e., "light" in the present disclosure) (hereinafter, also referred to as "irradiation step").

A substrate

The substrate is not particularly limited, and a substrate known as a support or a recording material can be used.

Examples of the substrate include: paper, paper laminated with plastic (e.g., Polyethylene, Polypropylene, Polystyrene, etc.), metal plate (e.g., a plate of metal such as aluminum, zinc, copper, etc.), plastic film (e.g., Polyvinyl Chloride (PVC) resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, Polyethylene Terephthalate (PET), Polyethylene (PE), Polystyrene (PS), Polypropylene (PP), Polycarbonate (PC), Polyvinyl acetal, acrylic resin, etc.), paper laminated with or evaporated with the above-mentioned metal, plastic film laminated with or evaporated with the above-mentioned metal, etc.

The ink of the present disclosure is particularly suitable for use in recording an image on a non-absorbent substrate because it can record an image having excellent adhesion to the substrate.

Herein, non-absorbent means waterHas an absorption amount of 0.3g/m²The following.

Water absorption amount (g/m) of substrate²) The measurement was carried out as follows.

Water was brought into contact with a 100mm × 100mm area on the front surface (i.e., the surface to be imaged) of the substrate, and the substrate was held at 25 ℃ for 1 minute in this state. The mass of water (absorption amount (g)) absorbed by holding for the 1 minute was obtained, and the obtained absorption amount (g) was converted into an absorption amount per unit area (g/m)²)。

As the non-absorbent substrate, a plastic substrate such as a polyvinyl chloride (PVC) substrate, a Polystyrene (PS) substrate, a Polycarbonate (PC) substrate, a polyethylene terephthalate (PET) substrate, a polypropylene (PP) substrate, an acrylic resin substrate, or the like is preferable.

(imparting step)

The applying step is a step of applying the ink of the present disclosure to a substrate by an ink jet method.

The ink can be applied by an ink jet method using a known ink jet recording apparatus.

The inkjet recording apparatus is not particularly limited, and a known inkjet recording apparatus capable of realizing a desired resolution can be arbitrarily selected. That is, a known inkjet recording apparatus including a commercially available product can be used.

Examples of the inkjet recording apparatus include an ink supply system, a temperature sensor, and a heating unit.

The ink supply system is constituted by, for example, a raw tank containing ink, a supply line, an ink supply tank immediately before the inkjet head, a filter, and a piezoelectric type inkjet head. The piezoelectric type inkjet head can be driven so as to be capable of ejecting dots of multiple sizes of preferably 1pL to 100pL, more preferably 8pL to 30pL at a resolution of preferably 320dpi (dot per inch) × 320dpi to 4000dpi × 4000dpi (dot per inch), more preferably 400dpi × 400dpi to 1600dpi × 1600dpi, and even more preferably 720dpi × 720dpi to 1600dpi × 1600 dpi.

Note that dpi indicates the number of dots per 2.54cm (1 inch).

(irradiation step)

The irradiation step is a step of irradiating the ink applied to the substrate with active energy rays.

The ink applied to the substrate is irradiated with active energy rays, thereby performing a polymerization reaction of the radical polymerizable monomer in the ink. As a result, the image can be fixed, and the hardness of the image can be improved.

Examples of the active energy ray that can be used in the irradiation step include: ultraviolet rays (UV light), visible rays, electron beams, and the like, and among them, UV light is preferable.

The peak wavelength of the active energy ray is preferably 200nm to 405nm, more preferably 220nm to 390nm, and still more preferably 220nm to 385 nm.

Further, it is preferably 200nm to 310nm, and also preferably 200nm to 280 nm.

The exposure energy upon irradiation with active energy rays is, for example, 10mJ/cm²～2000mJ/cm²Preferably 20mJ/cm²～1000mJ/cm²。

As a source for generating active energy rays, a mercury lamp, a metal halide lamp, a UV fluorescent lamp, a gas laser, a solid-state laser, and the like are widely known.

In addition, the light source is replaced by the semiconductor ultraviolet light-emitting device, so that the light source has very high application value in the aspects of industry and environment.

Among semiconductor ultraviolet light Emitting devices, leds (light Emitting diodes) and lds (laser diodes) are small, have a long life, high efficiency, and low cost, and are expected as light sources.

As the light source, a metal halide lamp, an ultra-high pressure mercury lamp, a medium pressure mercury lamp, a low pressure mercury lamp, an LED, or a blue-violet laser is preferable.

Among them, in the case of using a sensitizer and a photopolymerization initiator together, an ultrahigh-pressure mercury lamp capable of light irradiation with a wavelength of 365nm, 405nm, or 436nm, a high-pressure mercury lamp capable of light irradiation with a wavelength of 365nm, 405nm, or 436nm, or an LED capable of light irradiation with a wavelength of 355nm, 365nm, 385nm, 395nm, or 405nm is more preferable, and an LED capable of light irradiation with a wavelength of 355nm, 365nm, 385nm, 395nm, or 405nm is most preferable.

In the irradiation step, the irradiation time of the ink applied to the substrate by the active energy ray is, for example, 0.01 to 120 seconds, preferably 0.1 to 90 seconds.

The irradiation conditions and the irradiation method disclosed in Japanese patent laid-open No. 60-132767 can be applied to the irradiation conditions and the basic irradiation method as well.

As a method of irradiating the active energy ray, specifically, a method of providing light sources on both sides of a head unit of an ink ejection device and scanning the head unit and the light sources in a so-called reciprocating manner, or a method of irradiating the active energy ray by another light source without driving is preferable.

The irradiation with the active energy ray is preferably performed after the ink is dropped and heated and dried, and then performed at a constant time interval (for example, 0.01 to 120 seconds, preferably 0.01 to 60 seconds).

(Heat drying Process)

The image recording method may further include a heat drying step after the providing step and before the irradiating step, if necessary.

The heating unit is not particularly limited, and includes: hot drums, warm air, infrared lamps, hot ovens, hot plate heating, and the like.

The heating temperature is preferably 40 ℃ or higher, more preferably about 40 to 150 ℃, and further preferably about 40 to 80 ℃.

The heating time can be appropriately set according to the composition of the ink and the printing speed.

< image recorded matter >

The image recorded matter of the present disclosure includes a substrate and an image as a cured product of the ink of the present disclosure disposed on the substrate.

The image recorded matter of the present disclosure can be produced using the ink of the present disclosure which is excellent in curability and ejection property.

In addition, the stickiness of the surface of the image on the manufactured image recorded matter in a high temperature environment (for example, in an environment of 40 ℃) is suppressed.

In the image recorded matter of the present disclosure, the image as a cured product of the ink of the present disclosure preferably contains a copolymer including a structural unit derived from the monomer a, a structural unit derived from the monomer B, and a structural unit derived from the monomer C, and the total content of the structural unit derived from the monomer a, the structural unit derived from the monomer B, and the structural unit derived from the monomer C is 60 mass% or more with respect to the total amount of the copolymer.

The structural unit derived from the monomer a, the structural unit derived from the monomer B, and the structural unit derived from the monomer C are each a structural unit obtained by radical polymerization of the monomer a, a structural unit obtained by radical polymerization of the monomer B, and a structural unit obtained by radical polymerization of the monomer C.

Regarding the preferable range of the content ratio of these structural units in the copolymer, the above-mentioned ink can be appropriately referred to.

The copolymer may contain other structural units than the above structural units.

The image may contain other components than the copolymer.

With respect to the other constituent units and the other components, the above-mentioned ink can be appropriately referred to.

[ examples ]

Examples of the present disclosure are listed below, but the present disclosure is not limited to the following examples.

[ example 1]

< preparation of cyan pigment Dispersion >

The raw materials having the following composition were mixed and stirred at 2,500 rpm for 10 minutes using a stirrer (L4R manufactured by SILVERSON) to obtain a mixture. Then, the resultant mixture was charged into a bead mill disperser DISPERMAT LS (manufactured by VMA corporation), and dispersed at 2,500 rpm for 6 hours using YTZ balls (manufactured by NIKKATO, inc.) having a diameter of 0.65mm to obtain a cyan pigment dispersion (hereinafter, referred to as a C pigment dispersion).

Composition of-C pigment dispersion

IRGALITE BLUE GLVO (cyan pigment) manufactured by BASF corporation

… 40 parts by mass

SOLSPERSE32000 (Polymer dispersant), manufactured by LUBORONG, Japan

… 10 parts by mass

SR9003 (difunctional monomer, propoxylated (2) neopentyl glycol diacrylate) manufactured by SARTOMER

… 59 parts by mass

Firstcure ST-1 (polymerization inhibitor; tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, manufactured by Yabao Co., Ltd.)

… 1 parts by mass

< preparation of ink >

The following components were mixed to prepare an ink.

Composition of the ink

The above pigment dispersion C

… 7 parts by mass

N-vinyl oxazolidinone (hereinafter, also referred to as "NVO") (monomer A)

… 12 parts by mass

Isobornyl acrylate (hereinafter, also referred to as "IBOA") (monomer B)

… 38 parts by mass

Cyclic trimethylolpropane formal acrylate (hereinafter, also referred to as "CTFA") (monomer C)

… 28 parts by mass

Firstcure ST-1 (hereinafter, also referred to as "ST-1") (polymerization inhibitor) manufactured by Yabao Co., Ltd

… 1.1.1 parts by mass

IRGACURE 184 (hereinafter, also referred to as "IRG 184") manufactured by BASF corporation (photopolymerization initiator; carbonyl compound (specifically, 1-hydroxy-cyclohexyl-phenyl-ketone))

… 2.4.4 parts by mass

IRGACURE 819 (hereinafter, also referred to as "IRG 819") (photopolymerization initiator; acylphosphine oxide compound (specifically, bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide))

… 8.2.2 parts by mass

SPEEDCURE BP (hereinafter, also referred to as "BP") manufactured by Lambson (photopolymerization initiator; benzophenone)

… 3.2.2 parts by mass

BYK-307 (hereinafter, also referred to as "BYK 307") manufactured by BYK-Chemie corporation (silicone surfactant)

… 0.1.1 parts by mass

< image recording >

An inkjet recording apparatus including an inkjet head and a curing light source was prepared.

As the ink jet head, a piezoelectric type ink jet head Q-class Sapphire QS-256/10 (manufactured by FUJIFILM DIMATIX Co., Ltd., number of nozzles 256, minimum droplet volume 10pL, 50kHz) was used.

As the curing light source, a curing light source having 10 light emitting diodes (UV-LED, NC4U134 manufactured by japan chemical industry ltd., peak wavelength 385nm) disposed therein and having one (2 in total) light source on each of the left and right sides was used. The illumination of each light source was 1,500mW/cm²。

The ink is applied to the substrate by ejecting the ink from the ink jet head using the ink jet recording apparatus. The discharge temperature of the ink discharged from the ink jet head was set to 45 ℃.

The ink applied to the substrate is irradiated with UV light emitted from the curing light source, thereby curing the ink. The energy (exposure energy) of the irradiated UV light was set to 400mJ/cm²。

Through the above operation, an image as a cured film of the ink is recorded on the substrate. Hereinafter, the substrate on which an image is recorded is also referred to as an image-recorded material.

< evaluation >

The following evaluations were carried out.

The results are shown in Table 1.

(curing Property)

In accordance with the image recording, a solid image (solid image) having an average film thickness of 10 μm as a cured film of the ink was recorded on a polyethylene terephthalate (PET) substrate ("vie wful UV TP-188" manufactured by KIMOTO corporation), and an image recorded matter was obtained.

Within 10 minutes from completion of recording of the solid image (i.e., completion of irradiation with UV light), the PET substrate as a transfer substrate was placed on the solid image on the obtained image-recorded matter, and a load of 1kg/a6 size was applied. In this state, the image recorded matter and the transfer substrate were left under an environment of 40 ℃ for 1 day.

After 1 day, the transfer substrate was peeled off from the solid image on the image recorded matter, and the area of the image transferred from the solid image to the transfer substrate side was checked, and the transfer area was determined by the following equation.

Transfer area (%) × 100 (area of image transferred to transfer substrate side/contact area between transfer substrate and solid image)

Based on the obtained results, curability was evaluated by the following evaluation criteria.

Among the evaluation criteria below, the grade having the most excellent curability is "a".

Evaluation criteria for curability-

A: the transfer area is less than 1%.

B: the transfer area is 1% or more and less than 25%.

C: the transfer area is 25% or more and less than 50%.

D: the transfer area is 50% or more and less than 75%.

E: the transfer area is 75% or more.

(surface tackiness inhibitory Property)

According to the image recording, a solid image having an average film thickness of 10 μm was recorded on the PET substrate to obtain an image recorded matter.

The resulting image record was allowed to stand at 40 ℃ for 1 day.

The solid image on the image recorded matter after 1 day had elapsed was wiped with low-dust wiping paper (Kimwipes). In this case, the sticky feeling of the surface of the image was confirmed during the wiping operation, and after the wiping operation, the marks on the surface of the image after wiping with the low-dust wiping paper were confirmed, and the surface stickiness inhibition was evaluated according to the following evaluation criteria.

In the evaluation criteria below, the grade at which the surface tackiness of the image is most suppressed (i.e., the grade at which the surface tackiness is most suppressed) is "a".

Evaluation criteria for inhibition of surface tackiness-

A: the surface of the image was not sticky, and no mark after wiping was recognized on the surface of the image.

B: the surface of the image was slightly sticky, but no mark after wiping was recognized on the surface of the image.

C: the surface of the image was slightly felt tacky, and the mark after wiping was slightly recognized on the surface of the image.

D: the surface of the image was felt tacky, and traces after wiping were slightly recognizable on the surface of the image.

E: the surface of the image was felt tacky and a wiping mark was recognized on the surface of the image.

(spitting Property)

The ink ejection from the ink jet head of the ink jet recording apparatus is started, and then the ejection is suspended. After 10 minutes passed in this state, ink discharge was resumed, and a solid image having an average film thickness of 10 μm was recorded on the PET substrate in accordance with the image recording to obtain an image recorded matter.

The solid image on the image recording material was observed to confirm the nozzle clogging. Based on the results of the confirmation, the ejection property was evaluated by the following evaluation criteria.

Among the evaluation criteria below, the grade having the most excellent ejection property is "a".

Evaluation criteria for spitting Properties-

A: no nozzle clogging was confirmed.

B: clogging of 1 or 2 nozzles was observed.

C: clogging of 3 to 5 nozzles was confirmed.

D: 6 to 9 nozzles were found to be clogged.

E: clogging of 10 or more nozzles was observed.

[ examples 2 to 19, comparative examples 1 to 5]

The same operation as in example 1 was performed except that the composition of the ink was changed to the composition shown in table 1 or table 2.

The results are shown in table 1 or table 2.

In example 13, the following polymer 1 was contained as a resin in the ink. In the following polymer 1, the subscript shown on the lower right of each structural unit indicates the copolymerization mass ratio.

[ chemical formula 5]

Polymer 1 was synthesized as follows.

161.22g of 1-propanol (reaction solvent) and 42.50g of N-vinylcaprolactam (raw material monomer) were weighed into a 1000mL three-necked flask equipped with a cooling tube, and heated and stirred at 75 ℃ under a nitrogen stream.

Separately, 103.85g of 1-propanol, 152.50g of pentamethylpiperidinyl methacrylate (raw material monomer), 47.51g of methyl methacrylate (raw material monomer), 7.52g of dicyclopentenyloxyethyl methacrylate (raw material monomer), 13.33g of V-601 (initiator), and 7.03g of dodecylmercaptan were mixed, and the resulting mixed solution was added dropwise to the flask over 4 hours. After completion of the dropwise addition and heating at 75 ℃ for 1 hour, the mixture was stirred at 90 ℃ for 3 hours to allow the reaction to proceed.

The obtained reaction solution was cooled naturally, and the naturally cooled reaction solution was poured into a mixed solution of 2047.93g of water and 47.92g of methanol in an ice bath, followed by reprecipitation purification and vacuum drying.

By the above operation, about 241g of the polymer 1 (weight average molecular weight (Mw)11000) was obtained.

Description of tables 1 and 2

The numerical value in each component means the content (mass%) in the ink.

The blank column in the table means that the component is not contained.

The monomer a is a radically polymerizable monomer represented by the formula (a).

The monomer B is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure.

The monomer C is a radical polymerizable monomer having a heterocyclic structure.

"A + B" means the total content (mass%) of the monomer A and the monomer B.

"A + B + C" means the total content (mass%) of the monomer A, the monomer B and the monomer C.

"A/total monomer" means the content (mass%) of the monomer A relative to the total content of all radically polymerizable monomers contained in the ink. Here, the monomer in the C pigment dispersion (specifically, the aforementioned SR9003 as a bifunctional monomer) is also included in all the monomers.

Abbreviation in tables 1 and 2-

NVO: n-vinyl oxazolidinones

NVMO: n-vinyl-5-methyl oxazolidinones

IBOA: acrylic acid isobornyl ester

CHA: acrylic acid cyclohexyl ester

CTFA: cyclic trimethylolpropane formal acrylate

ACMO: acryloyl morpholine

MEDOL 10: (2-methyl-2-ethyl-1, 3-dioxolan-4-yl) methacrylate [ manufactured by Osaka organic chemical industries, Ltd ]

LA: acrylic acid lauryl ester

TMPTA: trimethylolpropane triacrylate

ST-1: firstcure ST-1 (polymerization inhibitor; tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, manufactured by Yabao Co., Ltd.)

IRG 184: IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone) manufactured by BASF corporation

IRG 819: IRGACURE 819 (bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide) from BASF corporation

BP: SPEEDCURE BP (benzophenone) manufactured by Lambson

BYK 307: BYK-307 (Silicone surfactant) manufactured by BYK-Chemie

As shown in tables 1 and 2, the examples using the following inks, each of which has excellent curability, surface tack inhibitory property, and ejection property, contain: a monomer A as a radical polymerizable monomer represented by the formula (A); a monomer B which is a radical polymerizable monomer containing an alicyclic structure and no heterocyclic structure; and a monomer C which is a radical polymerizable monomer having a heterocyclic structure, wherein the total content of the monomer A, the monomer B and the monomer C is 60% by mass or more relative to the total amount of the ink.

In comparative example 1, in which the ink did not contain the monomer a, the curability was lowered compared to the examples.

In comparative example 2 in which the ink did not contain the monomer B, curability and surface tack inhibition property were lowered.

In comparative example 3 in which the ink did not contain the monomer C, the ejection property was degraded.

In comparative examples 4 and 5 in which the total content of the monomer a, the monomer B, and the monomer C in the ink was less than 60 mass% with respect to the total amount of the ink, the curability was reduced.

From the results of examples 1 to 19, it is understood that the curability is further improved when the content of the monomer A is 10 to 30% by mass based on the total amount of the ink (examples 1, 2,4, and 6 to 19).

From the results of examples 4 and 6, it is understood that when the content of the monomer B is 20% by mass or more based on the total amount of the ink (example 4), the surface tack inhibiting property is further improved.

From the results of examples 7 and 18, it is understood that the ejection property is further improved when the content of the monomer B is 40 mass% or less with respect to the total amount of the ink (example 18).

From the results of examples 8 and 18, it is understood that the ejection property is further improved when the content of the monomer C is 20 mass% or more based on the total amount of the ink (example 18).

From the results of examples 9 and 19, it is understood that when the content of the monomer C is 40% by mass or less based on the total amount of the ink (example 19), the surface tackiness inhibitory property is further improved.

From the results of example 2, example 19 and the like, it is understood that curability is further improved when the content of the monomer a is 15 to 40% by mass based on the total content of all the radical polymerizable monomers contained in the ink (example 19 and the like).

In the above, examples of inks containing a cyan pigment as a colorant are listed as examples of the inks of the present disclosure.

Of course, in the inks of the above-described embodiments, the same effects as those of the embodiments can be obtained even when the colorant is changed to a colorant other than a cyan pigment (for example, a magenta pigment, a yellow pigment, a black pigment, a white pigment, etc.) or when the colorant is substantially not contained.

The disclosure of japanese patent application No. 2019-.

All documents, patent applications, and technical standards described in the present specification are incorporated by reference into the present specification to the same extent as if each document, patent application, and technical standard was specifically and individually described.