阅读说明：本技术 热敏记录体 (Thermosensitive recording medium ) 是由 平井健二 久津轮幸二 绿川佳美 于 2019-03-01 设计创作，主要内容包括：本发明的目的在于,提供一种热敏记录体,其在严酷环境下的呈色性能、特别是条形码读取适应性优异,此外,对于严酷条件下的变色具有耐性。本发明的热敏记录体在支承体上设有含有无色或浅色的给电子性隐色染料及电子接受性显色剂的热敏记录层,其特征在于,该热敏记录层中,作为电子接受性显色剂,以特定比含有特定的砜化合物及酚系化合物,任选还含有特定的脲氨基甲酸酯系化合物,所述酚系化合物包含2个以上的羟基及2个以上的二苯基砜骨架,且不包含氨基甲酸酯键及脲键。(The purpose of the present invention is to provide a thermosensitive recording medium which is excellent in color development performance under severe environments, particularly in barcode reading suitability, and which is resistant to discoloration under severe conditions. The thermosensitive recording medium of the present invention is characterized in that a thermosensitive recording layer containing a colorless or pale-colored electron-donating leuco dye and an electron-accepting color-developing agent is provided on a support, and the thermosensitive recording layer contains a specific sulfone compound and a specific phenol compound at a specific ratio as the electron-accepting color-developing agent, and optionally further contains a specific urea urethane compound, the phenol compound containing 2 or more hydroxyl groups and 2 or more diphenylsulfone skeletons and not containing a urethane bond and a urea bond.)

1. A thermosensitive recording medium comprising a thermosensitive recording layer containing a colorless or pale-colored electron-donating leuco dye and an electron-accepting color developing agent on a support,

the thermosensitive recording layer contains a sulfone compound represented by the following general formula 1 and a phenol compound as an electron accepting color developing agent,

in the formula, R¹Represents a hydrogen atom or a hydroxyl group, R²And R³Each independently represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, and m represents an integer of 1 to 3;

the phenolic compound is a compound containing 2 or more hydroxyl groups and 2 or more diphenyl sulfone skeletons and not containing urethane bonds and urea bonds, and the phenolic compound is contained in an amount of 0.01 to 1.0 part by weight based on 1 part by weight of the sulfone compound.

2. The thermosensitive recording body according to claim 1,

the thermosensitive recording layer further contains a urea urethane-based compound represented by the following general formula 8 as an electron accepting color developer:

3. the thermosensitive recording body according to claim 2,

the thermosensitive recording layer contains the urea urethane compound in an amount of 0.01 to 1.0 part by weight based on 1 part by weight of the sulfone compound.

4. The thermosensitive recording medium according to any one of claims 1 to 3,

the phenolic compound is represented by the following general formula 2:

in the formula, R⁴Each of which is the same or different and represents a halogen atom, an alkyl group or an alkenyl group having 1 to 6 carbon atoms, each of which is the same or different and represents an integer of 0 to 4, o represents an integer of 1 to 11, R⁵Each, optionally the same or different, represents: a saturated or unsaturated linear or branched hydrocarbon group having 1 to 12 carbon atoms, which optionally has an ether bond; a substituted phenylene group represented by the following general formula:

or

A 2-valent group represented by the following general formula:

in the formula, R⁷Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

5. The thermosensitive recording medium according to any one of claims 1 to 4,

the phenolic compound is contained in a proportion of 0.05 to 0.8 parts by weight relative to 1 part by weight of the sulfone compound.

6. The thermosensitive recording medium according to any one of claims 1 to 5,

the sulfone compound is represented by the following general formula 5:

in the formula, R²And R³As defined above, m is 1 or 2.

7. The thermosensitive recording medium according to any one of claims 1 to 6,

the R is²And R³At least one of them is a hydrogen atom.

8. The thermosensitive recording medium according to any one of claims 1 to 7,

and m is 1.

9. The thermosensitive recording medium according to any one of claims 1 to 8,

the phenolic compound is represented by the following formula:

Technical Field

The present invention relates to a thermosensitive recording medium which utilizes a color-developing reaction between a colorless or pale-colored electron-donating leuco dye (hereinafter also referred to as "leuco dye") and an electron-accepting color-developing agent (hereinafter also referred to as "color-developing agent"), and which is excellent in color-developing performance under severe environments, particularly in barcode reading suitability, and is resistant to discoloration under severe conditions.

Background

In general, a thermosensitive recording medium is a recording medium obtained by applying a coating liquid, which is obtained by grinding and dispersing a leuco dye having a colorless or pale color and a color-developing agent such as a phenolic compound into fine particles, mixing them, and adding a binder, a filler, a sensitivity enhancer, a lubricant, and other auxiliary agents, to a support such as paper, synthetic paper, a film, or plastic, and coloring the recording medium by a transient chemical reaction caused by heating with a thermal head, thermal imprint, a thermal pen, a laser beam, or the like, to obtain a recorded image. A thermosensitive recording medium is widely used as a recording medium for facsimiles, terminal printers for computers, ticket vending machines, measuring recorders, receipts for supermarkets, convenience stores, and the like.

In recent years, the applications of thermosensitive recording media have been expanded to various tickets, receipt and receipt applications, labels, ATM applications for banks, gas and electricity usage indicators, ticket exchanges for vehicle tickets, and the like, and there has been a demand for plasticizer resistance that does not cause a problem in reading suitability of a printed portion even when stored in contact with a film, synthetic leather, or the like for a long time under severe conditions such as storage properties of an image portion and a white paper portion in an environment such as a high temperature state in a vehicle in midsummer.

Therefore, a thermosensitive recording medium in which a specific color-developing agent and a stabilizer are used in combination to improve the storage stability of an image portion (patent document 1), a thermosensitive recording medium in which color development performance and the storage stability of an image portion are improved by using 2 specific color-developing agents in combination (patent document 2), a thermosensitive recording medium in which storage stability is improved by using 2 color-developing agents such as a phenol-based compound and a BPS-based color-developing agent in combination (patent documents 3 to 4), a thermosensitive recording medium in which 2 sulfone-based color-developing agents are used in combination (patent document 5), and the like have been disclosed.

The present inventors have also disclosed a thermosensitive recording medium in which 2 kinds of color developers of a urea urethane compound and a BPS compound are used in combination to improve color developability under severe environments, particularly barcode reading suitability (patent document 6).

Disclosure of Invention

Problems to be solved by the invention

When the thermosensitive recording medium is used for applications under severe environments such as labels and tickets, which have recently been expanded in use, the storage properties of the image portion and the blank sheet portion are important. For example, in the case of a thermal recording medium (patent document 2) or the like using a combination of 2 specific color developers, the white paper portion is colored and the barcode reading suitability is insufficient when the recording medium is used in applications in harsh environments because the heat resistance of the white paper portion is poor (see comparative examples 1, 2, 4, and 6 described later).

Therefore, the present inventors have developed a thermosensitive recording medium having excellent color developing performance under severe environment, particularly good barcode reading suitability, by using 2 kinds of color developers of a urea urethane compound and a BPS compound in combination (patent document 6).

However, as a result of examining the market, it has been found that the discoloration under severe conditions needs to be further improved in the thermosensitive recording medium (patent document 6) (see comparative example 3 described later).

Accordingly, an object of the present invention is to provide a thermosensitive recording medium which is excellent in color developability under severe environments, particularly in barcode reading suitability, and is resistant to discoloration under severe conditions.

In the present invention, the term "harsh environment" or "harsh conditions" means, for example, high temperature and/or high humidity conditions, the term "high temperature" means, for example, 70 ℃ or higher, and the term "high humidity" means, for example, 80% RH or higher. The harsh conditions include heating in a microwave oven (for example, heating at an energy of about 500 to 1500W for about 1 to 5 minutes).

For example, when a conventional thermosensitive recording medium is used for a food label, if the food label to which a printed food label is attached is heated in a microwave oven, the white paper portion of the food label is colored (discolored), the aesthetic appearance is impaired, and reading of the printed information of the food label becomes difficult (see comparative examples 1 to 4, and 6 described later).

Further, the importance of plasticizer resistance, which means that no problem occurs in the reading suitability of the printing portion even if stored in contact with a film, synthetic leather, or the like for a long time, is increasing.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above problems can be solved by containing a specific sulfone compound and a phenol compound containing 2 or more hydroxyl groups and 2 or more diphenylsulfone skeletons and not containing a urethane bond and a urea bond as a developer at a specific ratio in a thermosensitive recording layer, and have completed the present invention.

That is, the present invention is a thermosensitive recording medium having a thermosensitive recording layer containing a colorless or pale-colored electron-donating leuco dye and an electron-accepting color-developing agent on a support, the thermosensitive recording layer containing, as the electron-accepting color-developing agent, a sulfone compound represented by the following general formula (formula 1):

[ solution 1]

(in the formula, R¹Represents a hydrogen atom or a hydroxyl group, R²And R³Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group, and m represents an integer of 1 to 3. ) The phenolic compound isA compound containing 2 or more hydroxyl groups and 2 or more diphenyl sulfone skeletons and not containing urethane bonds and urea bonds, wherein the phenolic compound is contained in an amount of 0.01 to 1.0 part by weight based on 1 part by weight of the sulfone compound.

In order to further improve the plasticizer resistance, the thermosensitive recording layer may further contain a urea urethane compound represented by the following general formula (formula 8) as an electron accepting color developer.

[ solution 8]

Effects of the invention

According to the present invention, it is possible to provide a thermosensitive recording medium which is excellent in coloring performance, particularly in barcode reading adaptability, even under severe environments, and which is resistant to discoloration under severe conditions.

Further, by using 3 kinds of color developers containing urea urethane compounds, the plasticizer resistance can be further improved.

Detailed Description

The thermosensitive recording medium of the present invention is provided with a thermosensitive recording layer containing a colorless or pale leuco dye and a color-developing agent on a support, and the thermosensitive recording layer contains a specific sulfone compound and a specific phenol compound as the color-developing agent at a specific ratio.

The sulfone compound used in the present invention is represented by the following general formula (formula 1).

[ solution 1]

In the formula, R¹Represents a hydrogen atom or a hydroxyl group, preferably a hydroxyl group.

In addition, R²And R³Each independently represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. More preferably R²And R³At least one of (A) and (B) is a hydrogen atom, more preferably R²And R³Are all hydrogen atoms.

m is an integer of 1 to 3, preferably 1 or 2, more preferably 1.

Examples of the alkyl group include straight-chain or branched-chain alkyl groups having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a1, 2-dimethylpropyl group, a hexyl group, an isohexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a1, 1-dimethylbutyl group, a1, 2-dimethylbutyl group, a2, 2-dimethylbutyl group, a1, 3-dimethylbutyl group, a2, 3-dimethylbutyl group, a3, 3-dimethylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a1, 1, 2-trimethylpropyl group, a1, 2, 2-trimethylpropyl group, a 1-ethyl-1-methylpropyl group, i.e. methyl, ethyl, propyl, isopropyl.

Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group (pentyloxy group), an isopentyloxy group, a tert-pentyloxy group, a neopentyloxy group, a 2-methylbutyloxy group, a1, 2-dimethylpropoxy group, a 1-ethylpropoxy group, and a hexyloxy group, and methoxy, ethoxy, propoxy, and isopropoxy groups are preferable.

The preferable sulfone compound used in the present invention is represented by the following general formula (formula 5).

[ solution 5]

In the formula, R²、R³And m is as defined above.

More preferred sulfone compounds to be used in the present invention include 4-hydroxy-4 '-benzyloxydiphenyl sulfone, 4-hydroxy-4' -phenethyloxydiphenylsulfone and 4-hydroxy-4 '- (3-phenylpropoxy) diphenyl sulfone, and most preferred is 4-hydroxy-4' -benzyloxydiphenyl sulfone (formula 6).

[ solution 6]

The phenolic compound used in the present invention is a compound containing 2 or more, preferably 2 to 4, more preferably 2 hydroxyl groups, and 2 or more, preferably 2 to 12 diphenylsulfone skeletons, and not containing any of a urethane bond and a urea bond.

As such a phenol compound, a crosslinking type compound represented by the following general formula (formula 2) can be preferably mentioned.

[ solution 2]

In the above general formula (formula 2), R⁴Each of which is optionally the same or different, but preferably the same, represents a halogen atom, an alkyl group having 1 to 6 carbon atoms or an alkenyl group.

The alkyl or alkenyl group is an alkyl or alkenyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a vinyl group, an allyl group, an isopropenyl group, a 1-propenyl group, a 2-butenyl group, a 3-butenyl group, a1, 3-butadienyl group, and a 2-.

The halogen atom represents chlorine, bromine, fluorine or iodine, and preferably represents chlorine or bromine.

Each n is optionally the same or different, preferably the same, and represents 0 to 4, preferably 0.

OH group and-OR⁵The O-radical is preferably relative to SO₂The radical is in the para position.

o is 1 to 11. The compound is preferably a mixture with o of 1-11.

R⁵Each is optionally the same or different, but is preferablyThe same is true.

As R⁵The hydrocarbon group may be a saturated or unsaturated, preferably saturated, linear or branched, preferably linear hydrocarbon group having 1 to 12 carbon atoms, preferably 3 to 7 carbon atoms, which may optionally have an ether bond. As such a hydrocarbon group, a polyalkylene oxide chain and an alkylene group are preferable, and a polyalkylene oxide chain is more preferable. At R⁵In the case of polyalkylene oxide chains, as-OR⁵O-may be-O- (C)_pH_2pO)_1～3- (wherein p is 2 to 4, preferably 2 to 3, and more preferably 2). The alkylene group may include-C_qH_2q- (wherein q is 1 to 12, preferably 3 to 7).

In addition, as R⁵Substituted phenylene groups represented by the following general formula:

[ solution 3]

(in the formula, R⁶Represents a methylene group or an ethylene group. R⁶Preferably in alignment with each other. )

Further, as R⁵The substituent may be a 2-valent group represented by the following general formula:

[ solution 4]

(in the formula, R⁷Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom. )

As R⁵Among them, the above-mentioned saturated or unsaturated, linear or branched hydrocarbon group having 1 to 12 carbon atoms and optionally having an ether bond is preferable.

As the phenol compound represented by the above general formula (formula 2), a compound represented by the following formula (available as D-90, manufactured by Nippon Caoda Co., Ltd.) is preferable.

[ solution 7]

(mixture of 1 to 11 ═ n)

The thermosensitive recording layer of the present invention preferably contains a urea urethane compound represented by the following general formula (formula 8) as a color developer in addition to a specific sulfone compound and a specific phenol compound.

[ solution 8]

Specifically, the urea urethane compounds are 3 kinds represented by the following formulas (formula 10) to (formula 11), and they may be used alone or in combination of 2 or more.

[ solution 10]

[ solution 11]

[ solution 12]

In the thermosensitive recording layer of the present invention, the phenolic compound is contained as a color-developing agent in an amount of 0.01 to 1.0 part by weight based on 1 part by weight of the sulfone compound. In addition, the phenolic compound is preferably contained in an amount of 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, based on 1 part by weight of the sulfone compound in the thermosensitive recording layer. In addition, the phenolic compound is preferably contained in the thermosensitive recording layer in an amount of 0.8 parts by weight or less, more preferably 0.5 parts by weight or less, and still more preferably less than 0.5 parts by weight, based on 1 part by weight of the sulfone compound.

In addition, when the thermosensitive recording layer of the present invention further contains a urea urethane compound as a color developer, the urea urethane compound is contained in an amount of 0.01 to 1.0 part by weight based on 1 part by weight of the sulfone compound. In addition, the urea urethane compound is preferably contained in the thermosensitive recording layer in an amount of 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, based on 1 part by weight of the sulfone compound. In addition, the urea urethane compound is preferably contained in the thermosensitive recording layer in an amount of 0.8 parts by weight or less, more preferably 0.6 parts by weight or less, and still more preferably less than 0.6 parts by weight, based on 1 part by weight of the sulfone compound.

When the content ratio of the phenol compound to the sulfone compound is in this range, the color developability of the thermosensitive recording medium under severe conditions, particularly the barcode reading suitability, is optimized, and discoloration under severe conditions is suppressed (see examples described later). If the amount of the phenol compound is less than 0.01 part by weight based on 1 part by weight of the sulfone compound, barcode readability may be insufficient. If the amount of the phenol compound is more than 1.0 part by weight based on 1 part by weight of the sulfone compound, discoloration may be insufficiently suppressed.

In the case where the thermosensitive recording layer of the present invention further contains a urea urethane compound as a color developer, if the amount of the urea urethane compound is less than 0.01 part by weight based on 1 part by weight of the sulfone compound, plasticizer resistance may be insufficient. When the amount of the urea urethane compound is more than 1.0 part by weight based on 1 part by weight of the sulfone compound, the whiteness of the white paper portion may be lowered.

The thermosensitive recording layer of the present invention may contain, as the color-developer, a color-developer other than the sulfone compound, the phenol compound, and the urea urethane compound. However, the content of the sum of the sulfone compound, the phenol compound, and the urea urethane compound added as needed is preferably 50% by weight or more, more preferably 70% by weight or more, further preferably 90% by weight or more, and particularly preferably 100% by weight of the total color developer (including the sulfone compound, the phenol compound, and the urea urethane compound added as needed) contained in the thermosensitive recording layer, that is, the total color developer contained in the thermosensitive recording layer is the sulfone compound, the phenol compound, and the urea urethane compound added as needed.

Examples of the color-developer other than the sulfone compound, the phenol compound and the urea urethane compound used in the present invention include inorganic acidic substances such as activated clay, attapulgite, colloidal silica and aluminum silicate, 4 '-isopropylidenediphenol, 1-bis (4-hydroxyphenyl) cyclohexane, 2-bis (4-hydroxyphenyl) -4-methylpentane, 4' -dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4 '-dihydroxydiphenyl sulfone, 2, 4' -dihydroxydiphenyl sulfone, 4-hydroxy-4 '-isopropoxydiphenyl sulfone, 4-hydroxy-4' -n-propoxydiphenyl sulfone, 4-hydroxy-4 '-allyloxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4' -methyldiphenylsulfone, and urea urethane compound, 3, 4-dihydroxyphenyl-4 ' -methylphenylsulfone, 1- [ 4- (4-hydroxyphenylsulfonyl) phenoxy ] -4- [ 4- (4-isopropoxyphenylsulfonyl) phenoxy ] butane, the phenol condensation composition described in Japanese patent application laid-open No. 2003-154760, the aminobenzenesulfonamide derivative described in Japanese patent application laid-open No. 8-59603, bis (4-hydroxyphenyloxyethoxy) methane, 1, 5-bis (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, 1-bis (4-hydroxyphenyl) -1-phenylethane, 1, 4-bis [ α -methyl- α - (4 ' -hydroxyphenyl) ethyl ] benzene, 1, 3-bis [ α -methyl- α - (4 ' -hydroxyphenyl) ethyl ] benzene, bis (4-hydroxy-3-methylphenyl) sulfide, a salt thereof, and a pharmaceutically acceptable salt thereof, 2, 2 '-thiobis (3-tert-octylphenol), 2' -thiobis (4-tert-octylphenol), the compound described in WO02/081229 or Japanese patent application laid-open publication No. 2002-301873, and N, thiourea compounds such as N' -di-m-chlorophenylthiourea, p-chlorobenzoic acid, stearyl gallate, zinc bis [ 4- (N-octyloxycarbonylamino) salicylate ] dihydrate, aromatic carboxylic acids such as 4- [ 2- (p-methoxyphenoxy) ethyloxy ] salicylic acid, 4- [ 3- (p-tolylsulfonyl) propyloxy ] salicylic acid, and 5- [ p- (2-p-methoxyphenoxyethoxy) cumyl ] salicylic acid, salts of these aromatic carboxylic acids with polyvalent metal salts such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel, antipyrine complexes of zinc thiocyanate, and complex zinc salts of p-aldehyde benzoic acid and other aromatic carboxylic acids. These color developers may be used singly or in combination of 2 or more. 1- [ 4- (4-Hydroxyphenylsulfonyl) phenoxy ] -4- [ 4- (4-isopropoxyphenylsulfonyl) phenoxy ] butane is available, for example, as TOMILAC214, a product name of Mitsubishi chemical corporation, and the phenol condensation composition described in Japanese patent laid-open publication No. 2003-154760 is available, for example, as TOMILAC224, a product name of Mitsubishi chemical corporation. Further, the compounds described in WO02/081229 and the like are available under the trade names of NKK-395 and D-100 manufactured by Nippon Caoda corporation. Further, it may contain a metal chelate type coloring component such as a higher fatty acid metal double salt described in Japanese patent application laid-open No. 10-258577 and a polyhydroxy aromatic compound.

Various materials used for the thermosensitive recording layer of the thermosensitive recording medium of the present invention are exemplified below, but a binder, a crosslinking agent, a pigment, and the like may be used for a coating layer other than the thermosensitive recording layer, that is, a protective layer, an undercoat layer, and the like, which are provided as necessary, within a range not to hinder the desired effects on the above-described problems.

The leuco dye used in the present invention may be any leuco dye known in the field of conventional pressure-sensitive or thermal recording paper, and is not particularly limited, but is preferably a triphenylmethane compound, a fluorane compound, a fluorene compound, a divinyl compound, or the like. Specific examples of representative colorless or pale-colored dyes (dye precursors) are given below. These dye precursors may be used alone or in combination of 2 or more.

< triphenylmethane leuco dyes >

3, 3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [ alias crystal violet lactone ], 3-bis (p-dimethylaminophenyl) phthalide [ alias malachite green lactone ].

< fluorane-based leuco dyes >

3-diethylamino-6-methylfluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran, 3-diethylamino-6-methyl-7- (o-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran, 3-diethylamino-6-methyl-7- (m-methylanilino) fluoran, 3-diethylamino-6-methyl-7-n-octylanilino fluoran, 3-diethylamino-6-methyl-7-n-octylamino fluoran, 3-diethylamino-6-methyl-7-benzylaminofluoran, 3-diethylamino-6-methyl-7-dibenzylaminofluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-chloro-7-p-methylanilinofluoran, 3-diethylamino-6-ethoxyethyl-7-anilinofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (p-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-benzo [ a ] alkane, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-benzo [ c ] fluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran, 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluoran, 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran, 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran, 3-dibutylamino-6-methyl-7-chlorofluoran, 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran, 3-dibutylamino-6-chloro-7-anilino, 3-dibutylamino-6-methyl-7-p-methylanilino, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-fluoroanilino) fluoran, 3-di-N-pentylamino-6-methyl-7-anilinofluoran, 3-di-N-pentylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-di-N-pentylamino-7- (m-trifluoromethylanilino) fluoran, 3-di-N-pentylamino-6-chloro-7-anilinofluoran, 3-di-N-pentylamino-7- (p-chloroanilino) fluoran, 3-pyrrolidinyl-6-methyl-7-anilinofluoran, 3-piperidinyl-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3- (N-Ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluoran (3- (N- エチル -N- キシルアミノ) -6- メチル -7- (p- クロロアニリノ) フルオラン in the text supra), 3- (N-Ethyl-p-methylanilino) -6-methyl-7-anilinofluoran, 3- (N-Ethyl-N-isopentylamino) -6-chloro-7-anilinofluoran, 3- (N-Ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3- (N-Ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran, 3- (N-Ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluoran, 3-cyclohexylamino-6-chlorofluoroalkane, 2- (4-oxahexyl) -3-dimethylamino-6-methyl-7-anilinofluorane, 2- (4-oxahexyl) -3-diethylamino-6-methyl-7-anilinofluorane, 2- (4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane, 2-methyl-6-p- (p-dimethylaminophenyl) anilinofluorane, 2-methoxy-6-p- (p-dimethylaminophenyl) anilinofluorane, 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) anilinofluorane, 2-chloro-6-p- (p-dimethylaminophenyl) anilinofluorane, 2-nitro-6-p- (p-diethylaminophenyl) anilinofluorane, 2-amino-6-p- (p-diethylaminophenyl) anilinofluorane, 2-diethylamino-6-p- (p-diethylaminophenyl) anilinofluoran, 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) anilinofluoran, 2-benzyl-6-p- (p-phenylaminophenyl) anilinofluoran, 2-hydroxy-6-p- (p-phenylaminophenyl) anilinofluoran, 3-methyl-6-p- (p-dimethylaminophenyl) anilinofluoran, 3-diethylamino-6-p- (p-diethylaminophenyl) anilinofluoran, 3-diethylamino-6-p- (p-dibutylaminophenyl) anilinofluoran, 2, 4-dimethyl-6- [ (4-dimethylamino) anilino ] -fluoran.

< fluorene leuco dyes >

3, 6, 6 '-tris (dimethylamino) spiro [ fluorene-9, 3' -phthalide ], 3, 6, 6 '-tris (diethylamino) spiro [ fluorene-9, 3' -phthalide ].

< leuco dyes of divinyl System >

3, 3-bis [ 2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) vinyl ] -4, 5, 6, 7-tetrabenzophthalein, 3-bis [ 2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) vinyl ] -4, 5, 6, 7-tetrachlorophthalein, 3-bis [ 1, 1-bis (4-pyrrolidinylphenyl) ethen-2-yl ] -4, 5, 6, 7-tetrabenzophthalein, 3-bis [ 1- (4-methoxyphenyl) -1- (4-pyrrolidinylphenyl) ethen-2-yl ] -4, 5, 6, 7-tetrachlorophthalein.

< Others >

3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3, 6-bis (diethylamino) fluoran- γ - (3 '-nitro) anilinolactam, 3, 6-bis (diethylamino) fluoran- γ - (4' -nitro) anilinolactam, 1-bis [2 ', 2' -tetrakis (p-dimethylaminophenyl) -vinyl ] -2, 2-dicyanoethane, 1-bis [2 ', 2', 2 ", 2" -tetrakis (p-dimethylaminophenyl) -vinyl ] -2- β -naphthoylethane, 1-bis [2 ', 2', 2 ", 2" -tetrakis (p-dimethylaminophenyl) -vinyl ] -2, 2-diacetylethane, dimethyl bis [2, 2, 2 ', 2' -tetrakis (p-dimethylaminophenyl) -vinyl ] -methylmalonate.

As the sensitizer used in the present invention, conventionally known sensitizers can be used. Examples of the sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montanic acid wax, polyethylene wax, 1, 2-bis (3-methylphenoxy) ethane, p-benzylbiphenyl, β -benzyloxynaphthalene, 4-biphenyl-p-tolylether, m-terphenyl, 1, 2-diphenoxyethane, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl- α -naphthyl carbonate, 1, 4-diethoxynaphthalene, phenyl 1-hydroxy-2-naphthoate, o-xylene-bis (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl, 4' -ethylenedioxy-dibenzyl bisbenzoate, dibenzoyloxymethane, and mixtures thereof, 1, 2-bis (3-methylphenoxy) ethylene, bis [ 2- (4-methoxy-phenoxy) ethyl ] ether, methyl p-nitrobenzoate, phenyl p-toluenesulfonate, o-toluenesulfonamide, p-toluenesulfonamide and the like. These sensitizers may be used singly or in combination of 2 or more.

Examples of the pigment used in the present invention include kaolin, calcined kaolin, calcium carbonate, alumina, titanium oxide, magnesium carbonate, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, and silica, and they may be used in combination according to the required quality.

Examples of the binder used in the present invention include polyvinyl alcohols such as completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, and other modified polyvinyl alcohols, acrylic resins containing (meth) acrylic acid and a monomer component copolymerizable with (meth) acrylic acid (excluding olefins), cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, ethyl cellulose, acetyl cellulose, starches such as oxidized starch, etherified starch, and esterified starch, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, and the like, Casein, gum arabic, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylate, polyvinyl butyral, polystyrene and copolymers thereof, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, coumarone resins, and the like. These high molecular substances may be dissolved in a solvent such as water, alcohol, ketone, ester, or hydrocarbon, may be emulsified or dispersed in water or other medium to form a paste, or may be used in combination according to the required quality.

The content (solid content) of the binder in the thermosensitive recording layer is preferably about 5 to 25 wt%.

Examples of the crosslinking agent used in the present invention include zirconium compounds such as zirconium chloride, zirconium sulfate, zirconium nitrate, zirconium acetate, zirconium carbonate, zirconium stearate, zirconium octoate, zirconium silicate, zirconyl nitrate, potassium zirconium carbonate, ammonium zirconium carbonate, polyaldehyde compounds such as glyoxal, glutaraldehyde, aldehyde starch, methylolmelamine, melamine-formaldehyde resin, melamine-urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, iron chloride, magnesium chloride, borax, boric acid, alum, ammonium chloride, and the like.

Examples of the lubricant used in the present invention include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, silicone resins, and the like.

In the present invention, 4 '-butylidene (6-tert-butyl-3-methylphenol), 2' -di-tert-butyl-5, 5 '-dimethyl-4, 4' -sulfonyldiphenol, 1, 3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like may be added as a stabilizer for improving the oil resistance of the image portion, in a range that does not inhibit the desired effects on the above problems. Further, benzophenone-based or triazole-based ultraviolet absorbers, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

The type and amount of the leuco dye, color developing agent, sensitizer and other various components used in the thermosensitive recording layer of the present invention are not particularly limited, and are determined in accordance with the required performance and recording suitability, and generally about 0.5 to 10 parts by weight of color developing agent, 0.1 to 10 parts by weight of sensitizer, 0.5 to 20 parts by weight of pigment, 0.01 to 10 parts by weight of stabilizer and 0.01 to 10 parts by weight of other components are used per 1 part by weight of leuco dye.

In the present invention, the leuco dye, the color developer, and, if necessary, the additive materials are finely pulverized to a particle size of several micrometers or less by a pulverizer such as a ball mill, an attritor, a sand mill, or a suitable emulsifying apparatus, and a binder and various additive materials used according to the purpose are added to prepare a coating liquid. The solvent used in the coating liquid may be water or alcohol, and the solid content thereof is about 20 to 40 wt%.

The thermosensitive recording medium of the present invention may further have a protective layer provided on the thermosensitive recording layer.

The protective layer mainly contains a binder and a pigment, and a crosslinking agent may also be added thereto.

As the binder, those usable for the above-mentioned thermosensitive recording layer can be suitably used, and carboxyl-modified polyvinyl alcohol and non-core-shell acrylic resin are preferable. These binders may be used in 1 kind or 2 or more kinds.

As the crosslinking agent, those usable for the above-mentioned thermosensitive recording layer can be suitably used, and epichlorohydrin-based resins and polyamine/polyamide-based resins (excluding resins contained in epichlorohydrin-based resins) are preferable.

More preferably, the protective layer contains both the carboxyl-modified polyvinyl alcohol and the epichlorohydrin-based resin and the polyamine/polyamide-based resin, whereby the color development performance can be further improved.

The carboxyl-modified polyvinyl alcohol can be obtained, for example, as a reaction product of polyvinyl alcohol and a polycarboxylic acid such as fumaric acid, phthalic anhydride, mellitic anhydride, or itaconic anhydride, or an esterified product of such a reaction product, or a saponified product of a copolymer of vinyl acetate and an ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, or methacrylic acid. Specific examples of the production method include the methods exemplified in Japanese patent application laid-open No. 53-91995 and the like. The carboxyl group-modified polyvinyl alcohol preferably has a saponification degree of 72 to 100 mol% and a polymerization degree of 500 to 2400, more preferably 1000 to 2000.

The glass transition temperature (Tg) of the non-core-shell acrylic resin is preferably 95 ℃ or lower, and more preferably higher than 50 ℃. The Tg was determined using Differential Scanning Calorimetry (DSC).

The non-core-shell acrylic resin preferably contains (meth) acrylic acid and a monomer component copolymerizable with (meth) acrylic acid, and the amount of (meth) acrylic acid is 1 to 10 parts by weight per 100 parts by weight of the non-core-shell acrylic resin. The (meth) acrylic acid is alkali-soluble, and has a characteristic that the non-core-shell acrylic resin is made water-soluble by adding a neutralizing agent. When the non-core-shell acrylic resin is changed to a water-soluble resin, particularly when a pigment is contained in the protective layer, the binding property with the pigment is significantly improved, and the protective layer having excellent strength even under the condition that a large amount of the pigment is contained can be formed. Examples of the component copolymerizable with (meth) acrylic acid include alkyl acrylate resins such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and octyl (meth) acrylate, modified alkyl acrylate resins such as epoxy resins, silicone resins, and the above alkyl acrylate resins modified with styrene or a derivative thereof, (meth) acrylonitrile, acrylic esters, and hydroxyalkyl acrylates, and it is particularly preferable to blend (meth) acrylonitrile and/or methyl methacrylate. The (meth) acrylonitrile is preferably added in an amount of 15 to 70 parts per 100 parts of the non-core-shell acrylic resin. Methyl methacrylate is preferably contained in an amount of 20 to 80 parts based on 100 parts of the non-core-shell acrylic resin. When (meth) acrylonitrile and methyl methacrylate are contained, it is preferable to blend 15 to 18 parts of (meth) acrylonitrile in 100 parts of the non-core-shell acrylic resin and 20 to 80 parts of methyl methacrylate in 100 parts of the non-core-shell acrylic resin.

The epichlorohydrin resin is a resin characterized by containing an epoxy group in a molecule, and examples thereof include polyamide epichlorohydrin resin and polyamine epichlorohydrin resin, and these resins may be used alone or in combination. In addition, as the amine present in the main chain of the epichlorohydrin-based resin, a primary amine to quaternary ammonium substance can be used, and there is no particular limitation. Further, since the water resistance is good, the cationization degree and the molecular weight are preferably 5meq/g · Solid or less (measured at pH 7), and the molecular weight is preferably 50 ten thousand or more. Specific examples of the epichlorohydrin-based Resin include Sumirez Resin 650(30), Sumirez Resin 675A, Sumirez Resin 6615 (manufactured by sumitomo chemical corporation), WS4002, WS4020, WS4024, WS4030, WS4046, WS4010, and CP8970 (manufactured by starlight PMC corporation).

The polyamine/polyamide resin does not have an epoxy group in the molecule, and examples thereof include polyamide urea resin, polyalkylene polyamine resin, polyalkylene polyamide resin, polyamine polyurea resin, modified polyamine resin, modified polyamide resin, polyalkylene polyamine urea resin, polyalkylene polyamine polyamide polyurea resin, and the like, and these resins may be used alone or in combination. Specific examples of the polyamine/polyamide Resin include Sumirez Resin 302 (manufactured by Sumitomo chemical Co., Ltd.: polyamine polyurea Resin), Sumirez Resin 712 (manufactured by Sumitomo chemical Co., Ltd.: polyamine polyurea Resin), Sumirez Resin703 (manufactured by Sumitomo chemical Co., Ltd.: polyamine polyurea Resin), Sumirez Resin 636 (manufactured by Sumitomo chemical Co., Ltd.: polyamine polyurea Resin), Sumirez Resin SPI-100 (manufactured by Sumitomo chemical Co., Ltd.: modified polyamine Resin), Sumirez Resin SPI-102A (manufactured by Sumitomo chemical Co., Ltd.: modified polyamine Resin), Sumirez Resin SPI-106N (manufactured by Sumitomo chemical Co., Ltd.: modified polyamide Resin), Sumirez Resin SPI-203 (50) (manufactured by Sumitomo chemical Co., Ltd.), Sumirez Resin SPI-198 (manufactured by Sumitomo chemical Co., Ltd.), プリンティブ A-700, プリンティブ A-600 (manufactured by Asahi chemical Co., Ltd.), PA6500, PA6504, PA6634, PA6638, PA6640, PA6644, PA6646, PA6654, PA6702, PA6704 (made by Takara PMC Co., Ltd.: polyalkylene polyamine polyamide polyurea resin), CP8994 (made by Takara PMC Co., Ltd.: polyethylene imine resin), and the like. Although not particularly limited, a polyamine-based resin (polyalkylene polyamine resin, polyamine polyurea resin, modified polyamine resin, polyalkylene polyamine urea resin, polyalkylene polyamine polyamide polyurea resin) is preferably used because of a good print density.

The content of the epichlorohydrin resin and the polyamine/polyamide resin when used together with the carboxyl-modified polyvinyl alcohol in the protective layer is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, and still more preferably 10 to 40 parts by weight, based on 100 parts by weight of the carboxyl-modified polyvinyl alcohol.

As the pigment used for the protective layer, the pigment that can be used for the thermosensitive recording layer described above can be suitably used, but kaolin, calcined kaolin, aluminum hydroxide, and silica are preferable. These pigments may be used in 1 kind or 2 or more kinds.

The content (solid content) of the binder in the protective layer is preferably 20 wt% or more, and more preferably about 20 to 80 wt%, and when the protective layer contains a pigment, the content of the pigment and the binder is preferably about 30 to 300 parts by weight of the binder in terms of solid content with respect to 100 parts by weight of the pigment.

Various additives such as a crosslinking agent, a lubricant, a stabilizer, an ultraviolet absorber, a dispersant, an antifoaming agent, an antioxidant, and a fluorescent dye, which can be used for the thermosensitive recording layer, can be appropriately blended as necessary in the coating liquid of the protective layer.

The thermosensitive recording medium of the present invention may have an undercoat layer provided between the support and the thermosensitive recording layer.

The base coat mainly contains a binder and a pigment.

As the binder used for the undercoat layer, binders that can be used for the above-described thermosensitive recording layer can be suitably used. These binders may be used in 1 kind or 2 or more kinds.

As the pigment used in the undercoat layer, a conventionally generally used known pigment can be used, and specific examples thereof include inorganic pigments such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, kaolin, calcined kaolin, clay, and talc, and organic pigments such as plastic hollow particles. These pigments may be used in 1 kind or 2 or more kinds.

The plastic hollow particles of the present invention are fine hollow particles that have been already in a foamed state, and are particles in which a thermoplastic resin is used as a shell and air or other gas is contained inside. Examples of the thermoplastic resin include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, polyacrylonitrile, polybutadiene, and copolymers thereof. Particularly preferred are styrene resins such as polystyrene, acrylic resins such as polyacrylate and polyacrylonitrile, copolymers thereof, and copolymer resins mainly composed of polyvinylidene chloride and polyacrylonitrile. Such organic hollow particles are available as SX8782 manufactured by JSR company, MH5055 manufactured by ZEON corporation, MH8108A manufactured by Rohm & Haas Japan, ローペイク HP-91 manufactured by Rohm & Haas Japan, Microsphere manufactured by Songban grease company, and the like.

The hollow plastic particle of the present invention preferably has a volume hollow ratio of about 40 to 95%. By setting the volume hollow ratio to 40% or more, the heat insulating property can be improved, and the color developing performance can be further improved. On the other hand, if the content is 95% or less, the strength of the shell of the hollow particle is increased to effectively maintain the hollow state, and thus the primer layer having good surface strength is easily obtained. The volume hollow ratio is a value obtained as (D3/D3). times.100. In the formula, D represents the inner diameter of the organic hollow particle, and D represents the outer diameter of the organic hollow particle.

The pigment in the undercoat layer is usually 50 to 95 parts by weight, preferably 70 to 90 parts by weight, based on 100 parts by weight of the total solid content.

In the present invention, the undercoat layer preferably contains plastic hollow particles as a pigment. When the undercoat layer contains plastic hollow particles as the pigment, the undercoat layer preferably contains 15 wt% or more, more preferably 45 wt% or more, of the plastic hollow particles with respect to the total amount (solid content) of the pigment.

The inorganic pigment can be used as a pigment other than the plastic hollow particles contained in the undercoat layer, but calcined kaolin is preferably used.

Various additives such as a dispersant, a plasticizer, a pH adjuster, a defoaming agent, a water retaining agent, an antiseptic, a coloring dye, and an ultraviolet ray inhibitor may be appropriately blended in the coating liquid of the undercoat layer as necessary.

In the present invention, the method for applying the heat-sensitive recording layer and the coating layer other than the heat-sensitive recording layer is not particularly limited, and the coating can be performed according to a known and conventional technique. For example, an off-machine (Japanese text: オフマシン) coater or an in-machine (Japanese text: オンマシン) coater equipped with various coaters such as an air knife coater, a bar blade coater, an exhaust blade (Japanese text: ベントブレード) coater, an inclined blade (Japanese text: ベベルブレード) coater, a roll coater, and a curtain coater can be suitably selected and used.

The coating amount of the heat-sensitive recording layer and the coating layer other than the heat-sensitive recording layer is not particularly limited, and is determined in accordance with the required performance and recording suitability, but the coating amount of the heat-sensitive recording layer is generally 2 to 12g/m in terms of solid content²Left and right. The general coating amount of the base coat is 1 to 15g/m in terms of solid content²On the left and right sides, the general coating amount of the protective layer is 1 to 5g/m in terms of solid content²Left and right. Book (I)In the invention, the coating amount of the protective layer is preferably 1 to 3g/m in terms of solid content²。

After the application of each layer, various techniques known in the field of thermosensitive recording media may be added as needed, for example, smoothing treatment such as super-calendering.