JPH11301111A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thermal recording material with superior light-fastness. SOLUTION: In a thermal recording material employing a developing compound capable of thermally coloring an ordinarily hypochromic or hypochromic compound, there is provided with a copolymer of a benzophenone derivative and a polymeric vinyl compound expressed by formula, (in the formula, R1 shows a hydrogen atom, a 6 or less C alkyl group or an oxyalkyl group, A is a 4 or less C group, X is an ester combination, an amide combination or an ester combination, R3 is a hydrogen atom or a methyl group respectively, and (n) is 0 or 1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having excellent light resistance.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated is disclosed in JP-B-43-4160 and JP-B-45-14039.
And widely used. In general, a thermosensitive recording material is obtained by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing both.
Additives such as binders, sensitizers, fillers, lubricants, etc. are added to this to form a coating solution, which is applied to a support such as paper, film, synthetic paper, etc. One or both of them are melted and brought into contact with each other to obtain a color recording by a chemical reaction, and a sheet-like heat-sensitive recording material is usually prepared. A thermal printer with a built-in thermal head or the like is used for coloring the heat-sensitive recording sheet. Compared with other recording methods, this thermal recording method (1) produces no noise during recording, (2) does not require development and fixing,
(3) Maintenance-free, (4) Facsimile field, computer output, printer field such as calculator, etc.
It is widely used in the field of recorders for medical measurement, the field of automatic ticket vending machines, the field of heat-sensitive recording labels, and the like.

[0003] In recent years, the use of thermal recording sheets for labels and price tags has increased with the development of POS systems in retail stores, supermarkets, and the like. It is increasingly used for shelf goods such as daily necessities and luxury goods, or for prepaid cards in the transportation-related and service industries.

[0004]

However, conventional heat-sensitive labels found on fresh foods and daily commodities have insufficient water resistance, plasticizer resistance, oil resistance, etc., but insufficient light resistance. However, there is a disadvantage that label printing becomes faint or disappears under sunlight or prolonged illumination. Such a phenomenon is also observed when a thermosensitive color recording type document sheet or facsimile receiving paper is left on a desk or the like, which is also a problem with respect to document storage. This is a major technical challenge in the field of sheets, especially for long-term use and storage. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having excellent light resistance and high color density.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to improve the above-mentioned drawbacks of the heat-sensitive recording material, and have completed the present invention. That is, the present invention provides (1) a thermosensitive recording material using a colorless compound which is usually colorless or pale and a color-developing compound capable of forming the color-forming compound upon heating.

[0006]

Embedded image

(In the formula (1), R 1 is a hydrogen atom, an alkyl or oxyalkyl group having 6 or less carbon atoms, A is an alkylene or oxyalkylene group having 4 or less carbon atoms, X is an ester bond, an amide R3 represents a hydrogen atom or a methyl group, and n is 0 or 1.) A copolymer of a 2-hydroxybenzophenone derivative and a polymerizable vinyl compound represented by the following formula: (2) R 1 is a hydrogen atom, A is an oxyalkylene group having 4 or less carbon atoms, X is an ester bond, R 3 is a hydrogen atom or A thermosensitive recording material according to (1), wherein n is 0 or 1; (3) R1 is a hydrogen atom, and -AX- is an oxyethyloxycarbonyl group bonded to the 4-position; , R3 is a hydrogen atom or a methyl group, and n is 1; (1) the heat-sensitive recording material;
1 is a hydrogen atom, -X- is an oxycarbonyl group bonded to the 4-position, R3 is a hydrogen atom or a methyl group, and n is 0, (1) the thermosensitive recording material, (5) polymerizable The heat-sensitive recording material according to any one of (1) to (4), wherein the vinyl compound is an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Formula (1) used in the present invention
In the compound represented by the formula, R1 is a hydrogen atom, an alkyl group having 6 or less carbon atoms or an oxyalkyl group. R
Examples of the alkyl group having 6 or less carbon atoms in 1 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, and an isopentyl group. , A neopentyl group, a tert-pentyl group, an n-hexyl group, an isohexyl group and the like, and examples of the oxyalkyl group having 6 or less carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group and a hexyloxy group. And the like.

A is an alkylene or oxyalkylene group having 4 or less carbon atoms. As the alkylene group having 4 or less carbon atoms in A, for example, a methylene group, an ethylene group, a propylene group, a 1-butene group, a 2-butene group, an isobutylene group and the like, and as an oxyalkylene group having 4 or less carbon atoms, For example, a methyleneoxy group, an ethyleneoxy group, a propyleneoxy group, a 1-buteneoxy group,
Examples thereof include a 2-buteneoxy group and an isobutyleneoxy group. The substitution position of A is preferably p-position to the carbonyl group on the benzene ring, and when A is an oxyalkylene group, the oxygen atom is preferably bonded to the benzene ring. X is an ester bond, an amide bond, a urethane bond or an ether bond, and the carbonyl group of the ester bond and the amide bond is preferably bonded to the carbon atom having R3. Further, R3 is a hydrogen atom or a methyl group, and n is 0 or 1.

Specific examples of the compound represented by the formula (1) include, for example, 2-hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, 2-hydroxy-4- (2-acryloyloxy) Ethoxybenzophenone, 2-hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone, 2-hydroxy-4- (2-methyl-2-
Acryloyloxy) ethoxybenzophenone and the like.

Examples of the vinyl compound copolymerizable with the compound of the formula (1) include acrylonitrile, alkyl (meth) acrylate, alkyl vinyl ether, alkyl vinyl ester, styrene, ethyl vinyl, bitilbunyl, 2-ethylhexyl vinyl and the like. In this case, the carbon number of the alkyl group is not particularly limited, but is preferably 1 to 20. Examples of the alkyl (meth) acrylate include methyl (meth) acrylate,
Ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like,
Examples of the alkyl vinyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, and stearyl vinyl ether, and examples of the alkyl vinyl ester include vinyl acetate.

The copolymerization ratio of the compound of the formula (1) to the above-mentioned vinyl compound is preferably in the range of the compound of the formula (1): the above-mentioned vinyl compound = 5: 95 to 60:40 by weight.

The copolymer of the present invention obtained by reacting the 2-hydroxybenzophenone derivative of the formula (1) with a polymerizable vinyl compound is preferably used in the form of an aqueous emulsion when used, for example, as described in JP-A-6-73368. Kaihei 7
It is manufactured by the method described in the official gazette such as -126536.

The heat-sensitive recording material of the present invention is provided with a heat-sensitive color-forming layer comprising, as main components, a colorless or pale-colored color-forming compound and a color-developing compound capable of forming a color when heated. Further, an overcoat layer is provided on the heat-sensitive coloring layer, and when a copolymer of the compound of the formula (1) and the polymerizable vinyl compound is contained in the heat-sensitive coloring layer, the heat-sensitive coloring layer is formed by the formula (1) ) Is a layer containing a copolymer of the compound of the compound and the polymerizable vinyl compound, and when the layer is contained in the overcoat layer, the overcoat layer contains a copolymer of the compound of the formula (1) and the polymerizable vinyl compound. Layer. As the support, for example, paper, plastic sheet,
A sheet-like material such as synthetic paper is preferred.

In the present invention, when the thermosensitive coloring layer is a layer containing a copolymer of the compound of the formula (1) and a polymerizable vinyl compound, the content of the copolymer is determined by the total content of the thermosensitive coloring layer. 1 to 60% by weight, preferably 5%, based on 100% by weight
To 30% by weight, for example, 1 to 5
0% by weight, 5-80% by weight of a color-developing compound, 0-80% by weight of each of a binder, a filler and a heat-fusible compound (sensitizer), other lubricants, surfactants, defoamers, etc. Are used at arbitrary ratios, for example, 0 to 30% by weight, respectively. The weight% is the weight ratio of each component in the thermosensitive coloring layer.

When the overcoat layer is a layer containing a copolymer of the compound of the formula (1) and a polymerizable vinyl compound, the copolymer is contained in the overcoat layer. 5 to 95 with the total weight as 100%
% By weight, preferably 40 to 90% by weight. still,
The copolymer may be contained in both the thermosensitive coloring layer and the overcoat layer.

Examples of the color-forming compound used in the heat-sensitive coloring layer are not particularly limited as long as they are those generally used in pressure-sensitive recording paper or heat-sensitive recording paper. In particular,
Examples include fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds.

As the fluoran compound, for example, 3-
Diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-N-isopentylamino) -6-methyl-7
-Anilinofluoran, 3-isobutylethylamino-
6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-
Hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino)
-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-
7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluoran, 3- (p-toluidine Noethylamino)
-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino)
Fluorane, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-
Fluoroanilino) fluoran, 3-dibutylamino-
7- (o-fluoroanilino) fluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro -7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-
7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-
Methylfluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-phenylfluoran, 3- (p-toluidinoethylamino) -6
-Methyl-7-phenethylfluoran and the like.

Examples of tolylmethane compounds include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL) and 3,3-bis (p-dimethylamino). Phenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindole-
3- (yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-
Phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) ) -6-Dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3- (2-phenylindol-3-yl) -5-dimethyl Aminophthalide, 3-p-dimethylaminophenyl-3- (1-
Methylpyrrole-2-yl) -6-dimethylaminophthalide and the like.

As the spiro compound, for example, 3-
Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3′-dichlorospirodinaphthopyran,
3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2 '-
And diphenylmethane-based compounds such as N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenyl leuco auramine Examples of the thiazine-based compound include benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue. Examples of the lactam-based compound include rhodamine B anilinolactam.
Rhodamine B-p-chloroanilinolactam and the like are fluorene-based compounds, for example, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-dimethylaminophthalide, 3,6-bis (Dimethylamino)
Fluorene spiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorene spiro (9,3')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color-developing compound is not particularly limited as long as it is generally used for pressure-sensitive recording paper or thermal recording paper.
For example, a phenolic compound, an aromatic carboxylic acid derivative having a phenolic hydroxyl group, an aromatic carboxylic acid or a metal salt thereof, and the like can be given.

As the phenolic compound, for example, α-
Naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-
Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (also called bisphenol A)
Or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p-hydroxyphenyl)
Cyclohexane, 4,4′-thiobisphenol, 4,
4'-cyclohexylidenediphenol, 2,2'-
(2,5-dibromo-4-hydroxyphenyl) propane, 4,4-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4′-dihydroxydiphenylsulfone 2,4′-dihydroxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
-Hydroxy-4'-methoxydiphenyl sulfone, 4
-Hydroxy-4'-ethoxydiphenyl sulfone, 4
-Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone and the like.

Examples of the aromatic carboxylic acid derivative or aromatic carboxylic acid include methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, Phenolic compounds such as -dihydroxy-2'-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and the like.

Examples of usable binders include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, and the like. Aqueous solutions such as polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salts of styrene / maleic anhydride copolymers, and iso (or diiso) butylene / maleic anhydride copolymer salts Of nature or styrene /
Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, polyvinyl acetate, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polystyrene, Hydrophobicity of acrylic resin, acrylic / styrene resin, polyacrylate, polyester, polycarbonate, polyurethane, polybutyral, epoxy resin, furan resin, vinyltoluene resin, rosin ester resin, composite particles of colloidal silica and acrylic copolymer, etc. Polymer compounds or their emulsions.

Examples of the filler that can be used include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, and acrylic resin. , Polyolefin resin, benzoguanamine resin, melamine resin, urea-formalin resin and the like.

Examples of the heat-fusible compound that can be used include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, aromatic ethers, Aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives,
Biphenyl derivatives, terphenyl derivatives, and the like that are solid at room temperature and have a melting point of about 70 ° C. or more can be used.

Examples of the waxes include wood wax, carnauba wax, shellac, paraffin, montan wax,
Paraffin oxide, polyethylene wax, polyethylene oxide and the like, as higher fatty acids, for example, stearic acid,
Examples of higher fatty acid amides such as behenic acid include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, and ethylenebisstearin Examples of acid amides include higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide, and examples of acetylated aromatic amines include acetotoluizide.

As the naphthalene derivative, for example, 1
-Benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like, as aromatic ethers, for example, 1,2-diphenoxyethane, 1,4-diphenoxyethane, 1,2-bis ( 3-methylphenoxy) ethane, 1,2-bis (4
-Methoxyphenoxy) ethane, 1,2-bis (3,4
-Dimethylphenyl) ethane, 1-phenoxy-2-
(4-chlorophenoxy) ethane, 1-phenoxy-2
Examples of aromatic carboxylic acid derivatives include-(4-methoxyphenoxy) ethane and the like. Examples of aromatic carboxylic acid derivatives include p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, terephthalic acid dibenzyl ester and the like. Derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, and the like. Carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate. (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like include biphenyl derivatives such as p-benzylbiphenyl and p-benzylbiphenyl.
-Allyloxybiphenyl and the like, and terphenyl derivatives include, for example, m-terphenyl and the like.

Other lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, defoamers and the like are added as required.

Using the above materials, the heat-sensitive recording material of the present invention is prepared, for example, by the following method. That is, first, the color-forming compound and the color-developing compound are separately pulverized and dispersed in a dispersing machine such as a ball mill, an attritor, and a sand mill together with a binder or other additives as necessary (pulverization, When the dispersion is carried out by a wet method, water is usually used as a medium), and an aqueous emulsion obtained by emulsion-polymerizing the dispersion of the two and the compound of the formula (1) and the polymerizable vinyl compound is mixed to prepare a thermosensitive coloring layer coating solution. On a support such as paper, plastic sheet, synthetic paper, etc., usually 1 to 20 g / m @ 2 in dry weight (square meter, the same applies hereinafter)
By a bar coater, a blade coater, or the like (the ratio of the color-forming compound to the color-developing compound is usually from 2: 1 to 1:10 by dry weight ratio), dried, and dried. Get.

When the overcoat layer contains a copolymer of the compound of the formula (1) and a polymerizable vinyl compound, the copolymer may be heat-sensitive together with a binder, a filler and other additives, if necessary. After forming the overcoat layer coating solution in the same manner as in the preparation of the color forming layer coating solution, the dry weight is usually 0.1 to 10 g / m2, preferably 0.5 to 3 g / m2.
It is applied so that it becomes 2.

[0032]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight.

Example 1 (Formation of thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 2 μm or less, to prepare solutions [A] and [B], respectively. I do. [A] solution: 3-dibutylamino-7- (o-chloroanilino) fluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts 25% PVA aqueous solution 20 parts Water 55 parts Separately, the monomer component ratio of the copolymer was 2-hydroxy-4
-Emulsion polymerization of 30 parts of (2-methacryloyloxy) ethoxybenzophenone, 85 parts of ethyl acrylate, and 5 parts of 2-ethylhexyl acrylate was carried out, and an aqueous emulsion of a copolymer corresponding to the formula (1) (solid content of 40 parts) was obtained.
%) [C] solution is prepared.

Next, each of the prepared solutions was mixed at the following ratio to prepare a coating solution for the heat-sensitive coloring layer. The coated solution was coated on a high-quality paper having a basis weight of 50 g / m 2 so that the weight when dried was 8 g / m 2 and dried. A thermosensitive coloring layer is obtained. [A] liquid 8 parts [B] liquid 16 parts [C] liquid 10 parts 20% methylol stearic acid amide aqueous dispersion 15 parts 50% calcium carbonate aqueous dispersion 10 parts Water 21 parts (formation of protective layer) Is applied to the thermosensitive coloring layer so as to have a dry weight of 3 g / m @ 2 and dried to obtain the thermosensitive recording material of the present invention. 15% PVA aqueous solution 100 parts 50% clay dispersion 10 parts 30% glyoxal aqueous solution 1 part

Examples 2 to 8 In the same manner as in Example 1 except that the solution [C] described in Example 1 was replaced with a 40% aqueous emulsion of a copolymer produced at the monomer component ratio shown in Table 1 below. To obtain the heat-sensitive recording material of the present invention.

[0036]

TABLE 1 Monomer component ratio of copolymer Example 2-Hydroxybenzophenone derivative / vinyl compound 2 2-Hydroxy-4-methacryloyloxybenzophenone 30 parts Butyl acrylate 70 parts Stearyl acrylate 20 parts 3 2-Hydroxy-4- Acryloyloxybenzophenone 30 parts Methyl methacrylate 60 parts 2-ethylhexyl acrylate 30 parts 4 2-hydroxy-4- (2-methyl-acryloyloxy) ethoxy benzophenone 30 parts Ethyl acrylate 70 parts Lauryl acrylate 20 parts 5 2-hydroxy-4- ( 2-methacryloyloxy) ethoxybenzophenone 30 parts Methyl methacrylate 70 parts 2-hydroxyethyl methacrylate 20 parts 6 2-hydroxy-4-methacryloylo Cibenzophenone 30 parts Styrene 80 parts n-butyl acrylate 10 parts 7 2-hydroxy-4-acryloyloxybenzophenone 30 parts Acrylonitrile 60 parts Ethyl methacrylate 30 parts 8 2-hydroxy-4- (2-methyl-acryloyloxy) ethoxy benzophenone 30 Part acrylonitrile 70 parts

Example 9 Instead of 3-dibutylamino-7- (o-chloroanilino) fluoran described in Example 1, 3-dibutylamino-
The heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using 6-methyl-7-anilinofluoran.

Example 10 The procedure of Example 1 was repeated, except that 3-dipentylamino-6-methyl-7-anilinofluorane was used in place of the 3-dibutylamino-7- (o-chloroanilino) fluoran described in Example 1. To obtain the heat-sensitive recording material of the present invention.

Example 11 The present invention was carried out in the same manner as in Example 1 except that bis (3-allyl-4-hydroxyphenyl) sulfone described in Example 1 was replaced with 4-hydroxy-4'-isopropoxydiphenylsulfone. Is obtained.

Example 12 (Formation of Thermosensitive Coloring Layer) Each of the prepared solutions was mixed in the following ratio to prepare a coating solution for the thermosensitive coloring layer, and the weight of the dried color was 8 g / m2 on a high-quality paper having a basis weight of 50 g / m2. Is applied and dried to obtain a thermosensitive coloring layer. [A] Liquid 8 parts [B] Liquid 16 parts 20% methylol stearic acid amide aqueous dispersion 15 parts 50% calcium carbonate aqueous dispersion 10 parts 50% carboxylated styrene / butadiene copolymer latex 8 parts Water 21 parts (protection) (Formation of Layer) Further, a coating solution for a protective layer having the following ratio is applied on the thermosensitive coloring layer so as to have a dry weight of 3 g / m @ 2 and dried to obtain a thermosensitive recording material of the present invention. Solution [C] described in Example 1 30 parts 30% aqueous solution of zinc stearate 10 parts 50% clay dispersion 10 parts

Comparative Example 1 A heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that the liquid [C] described in Example 1 was replaced with a 50% carboxylated styrene / butadiene copolymer latex.

Table 1 shows the quality performance of the heat-sensitive recording materials of Examples 1 to 12 of the present invention and comparative heat-sensitive recording materials obtained as described above.

[0043]

Table 2 Quality performance test Background 1) Color density 2) Light fast background 3) Light fast image 3) Example 1 0.05 1.52 0.08 1.50 Example 2 0.05 1 0.51 0.08 1.50 Example 3 0.05 1.52 0.08 1.51 Example 4 0.05 1.52 0.08 1.50 Example 5 0.05 1.52 0.08 1.51 Example 6 0.05 1.53 0.09 1.50 Example 7 0.05 1.52 0.08 1.51 Example 8 0.05 1.51 0.08 1.51 Example 9 0.06 1.54 0.09 1.53 Example 10 0.05 1.53 0.08 1.53 Example 11 0.05 1.52 0.07 1.48 Example 12 0.05 1 0.53 0.07 1.52 Comparative Example 1 0.05 1.51 0.25 0.98

1) Background: A value measured by a Macbeth reflection densitometer RD-914 of an uncolored sample. 2) Color density: Thermal printer (D
-805P) Macbeth reflection densitometer R of the colored portion printed with
Measured value with model D-914. 3) Light fastness: A value measured by a Macbeth reflection densitometer RD-914 of a color-developed portion of the sample after leaving the sample colored by the above-mentioned printer at the southern window exposed to sunlight for one week.

As is evident from Table 2, the heat-sensitive recording material of the present invention has a high coloring density and is excellent in light resistance of a background portion and a color image portion.

[0046]

According to the present invention, 2 represented by the formula (1)
-A heat-sensitive layer having a high color-forming density, and excellent background and light-fastness of a color-formed image by containing a copolymer of a hydroxybenzophenone derivative and a polymerizable vinyl compound in the heat-sensitive coloring layer and / or a layer thereon. A recording material is obtained.

Claims (5)

[Claims] 1. A heat-sensitive recording material comprising a colorless or pale-colored color-forming compound and a color-developing compound capable of causing the color-forming compound to develop a color when heated, which is represented by the following formula (1). (In the formula (1), R1 is a hydrogen atom, an alkyl group or an oxyalkylene group having 6 or less carbon atoms, A is an alkylene group or an oxyalkylene group having 4 or less carbon atoms, X is an ester bond, an amide bond, a urethane R3 represents a hydrogen atom or a methyl group;
Is 0 or 1. A heat-sensitive recording material comprising a layer containing a copolymer of a 2-hydroxybenzophenone derivative represented by the formula (1) and a polymerizable vinyl compound. 2. R1 is a hydrogen atom, and A has 4 carbon atoms.
2. The heat-sensitive recording material according to claim 1, wherein X is an ester bond, R3 is a hydrogen atom or a methyl group, and n is 0 or 1. (3) R1 is a hydrogen atom, an oxyethyloxycarbonyl group in which -AX- is bonded to the 4-position,
3. The heat-sensitive recording material according to claim 1, wherein 3 is a hydrogen atom or a methyl group, and n is 1. 4. The heat-sensitive recording material according to claim 1, wherein R1 is a hydrogen atom, -X- is an oxycarbonyl group bonded to the 4-position, R3 is a hydrogen atom or a methyl group, and n is 0. 5. The heat-sensitive recording material according to claim 1, wherein the polymerizable vinyl compound is an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms.