JP2000025335A - Thermal recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance adhesiveness and glossiness at every layer, and obtain high-grade feelings by containing a colloidal inorganic silicate, a water soluble polymeric compound, and a hydrophobic polymeric compound in an intermediate layer in a thermal recording body including a radiation-curable type overcoat layer formed on a thermal coloring layer via the intermediate layer. SOLUTION: A thermal recording body is formed by providing a thermal coloring layer, an intermediate layer containing colloidal inorganic silicate, a water soluble polymeric compound and a hydrophobic polymeric compound, and a radiation curable overcoat layer on the support body in this order. This intermediate layer is formed by containing, e.g. 5-70 wt.% colloidal inorganic silicate, 5-75 wt.% water soluble polymeric compound, 20-85 wt.% hydrophobic polymeric compound, and another lubricant, surface active agent, antifoaming agent or the like. As such a water soluble polymeric compound, an alkali salt of a copolymeric compound of maleic acid anhydride and N-phenylmaleimide or vinyl alcohol are used, thereby making high glossiness and obtaining high- grade feelings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermosensitive recording medium. More specifically, the present invention relates to a high-gloss, high-grade thermal recording medium having excellent adhesion, suitability for head matching during printing, and preservability of the thermal recording medium before and after coloring.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording medium for obtaining a recorded image by reacting a colorless or light-colored basic dye with an organic or inorganic colorant by heat is relatively inexpensive, and the apparatus is compact and maintenance-free. Therefore, in the field of facsimile and printers in recent years, the demand for thermal recording media such as POS labels, overhead projectors (OHP), second original drawings such as design drawings, cards and the like has been expanding.

[0003] However, these heat-sensitive recording materials have problems in storage stability (especially, discoloration of a color image due to a plasticizer, oil, or water), and also have disadvantages such as background fogging. As a method for solving this problem, a method of providing an ultraviolet curable resin layer on the thermosensitive coloring layer (Japanese Patent Publication No. 58-35478) or a method of providing an electron beam curable resin layer on the thermosensitive coloring layer via an intermediate layer And the like have been proposed (JP-A-59-26291).

[0004]

However, in the method of providing the radiation-curable resin layer on the heat-sensitive color-forming layer, the radiation-curable resin or a commonly used diluting solvent is used to coat the heat-sensitive color-forming layer. , And it was not practical. Also, with the method of providing a radiation-curable resin layer via an intermediate layer on the heat-sensitive coloring layer, with the recent diversification of heat-sensitive recording methods and higher performance, the hardware of thermal printers, facsimile machines, etc. has made remarkable progress. Adhesion to the thermal head and generation of noise during printing (sticking noise) in high-speed printing by a printer or printing by a video printer
And so on. In order to increase the commercial value of thermal recording media, high gloss products are required in the market,
High-gloss thermosensitive recording media tend to stick to the thermal head especially during printing, so it is easy to make printing noises, make fine scratches on the surface of the colored area, or distorted or shrink the colored image. There was a tendency that it was easy to wear.

[0005] Further, if the smoothness of the intermediate layer is increased to improve the uniformity of the image by providing a radiation-curable resin layer via the intermediate layer, the adhesion of the radiation-curable resin to the overcoat decreases. There is a problem of doing. In addition, in order to obtain a high-gloss thermosensitive recording medium, when forming an overcoat layer, it is common to dilute with a solvent or the like in many cases, but to improve the uniformity of the image, an intermediate layer is generally used. If the coating amount is reduced, the diluting solvent etc. will penetrate into the heat-sensitive coloring layer during coating, and the background will easily be covered. With this, storage stability such as water resistance, plasticizer resistance, etc., as well as head matching during printing Suitability also tended to be poor. In any case, the object of obtaining a high-quality heat-sensitive recording medium having excellent storage stability such as water resistance and plasticizer resistance, good head matching, and high quality has not yet been achieved.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides (1) a heat-sensitive color-developing layer containing a colorless or pale-colored color-forming compound and a color-developing compound capable of causing the color-forming compound to develop color when heated on a support, and an intermediate layer interposed therebetween. In a thermosensitive recording medium having a radiation-curable overcoat layer formed thereon, the intermediate layer contains a colloidal inorganic silicate, a water-soluble polymer compound, and a hydrophobic polymer compound. (2) The heat-sensitive recording material according to (1), wherein the water-soluble polymer compound is an alkali salt of a copolymer of isobutylene / maleic anhydride / N-phenylmaleimide or polyvinyl alcohol.

The heat-sensitive recording material of the present invention has good adhesion to each layer, uniform images, no background fouling, good head matching with a thermal head, high gloss and high quality. Has features.

The heat-sensitive recording medium of the present invention comprises a heat-sensitive coloring layer, an intermediate layer containing a colloidal inorganic silicate, a water-soluble polymer compound and a hydrophobic polymer compound on a support, and a radiation-curable overcoat. The coat layer is formed in this order. In the present invention, the heat-sensitive color-forming layer is mainly composed of 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, and comprises a binder as shown below and other optional components. Contains sensitizers, fillers, and other additives

In forming the thermosensitive coloring layer according to the present invention, the color-forming compound is 1 to 50% by weight, the color-developing compound is 5 to 80% by weight, the binder is 1 to 90% by weight, the filler and the heat-sensitive layer. Each of the fusible compounds (sensitizers) is 0 to 80% by weight,
In addition, a lubricant, a surfactant, an antifoaming agent, an ultraviolet absorber and the like are each used in an arbitrary ratio, for example, 0 to 30% by weight. The weight% is the weight ratio of each component in the thermosensitive coloring layer.

Examples of the coloring compound used in the heat-sensitive coloring layer are not particularly limited as long as they are generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples include, for example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds,
Thiazine compounds, lactam compounds, fluorene compounds and the like are mentioned.

The fluoran compounds include, 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 triarylmethane compounds include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL) and 3,3-bis (p-dimethylaminophenyl) phthalide , 3- (p-dimethylaminophenyl)-
3- (1,2-dimethylaminoindol-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-dimethylaminophthalide, 3
-P-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

Examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran,
Benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'- Benzopyran) and the like, as diphenylmethane compounds, for example, N-halophenyl-leuco auramine,
4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucouramine and the like; thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue; Examples of the fluorene-based compound include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and examples of the fluorene-based compound include 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6. '-Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3')-6'-pyrrolidinophthalide,
3-dimethylamino-6-diethylaminofluorenespiro (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 in pressure-sensitive recording paper or heat-sensitive recording paper. Specifically, 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 (alias: 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-chloroenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methoxy Diphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-butoxydiphenyl sulfone, methyl bis (4-hydroxyphenyl) acetate, bis (4 -Hydroxyphenyl) butyl acetate, bis (4-hydroxy Phenyl) phenolic compounds such as benzyl acetate, 2,4-dihydroxy-2'-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate , 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, aromatic carboxylic acid derivatives such as 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and metal salts thereof. .

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 resins, benzoguanamine resins, melamine resins, urea-formalin resins and the like.

Examples of the heat-fusible compound that can be used include waxes such as animal and plant waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, aromatic ethers, and the like. Aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives,
Examples include biphenyl derivatives and terphenyl derivatives which are solid at ordinary temperature and have a melting point of about 70 ° C. or higher. These usually act as sensitizers for increasing color sensitivity.

Examples of 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 Acid amides and the like; higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide; acetylated aromatic amines such as acetotoluide; naphthalene derivatives such as 1-benzyloxynaphthalene and 2-benzyloxynaphthalene; Benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like include aromatic ethers such as 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- (4-methoxyphenoxy) ethane and the like include aromatic carboxylic acid derivatives such as benzyl p-hydroxybenzoate,
Examples of aromatic sulfonic acid ester derivatives include benzyl p-benzyloxybenzoate and dibenzyl terephthalate, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylene sulfonate,
-Methylphenyl mesitylenesulfonate and the like are carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate (4
-Methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like, as biphenyl derivatives,
For example, p-benzylbiphenyl, p-allyloxybiphenyl and the like are terphenyl derivatives such as m-
Terphenyl and the like are each exemplified.

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

Using the above materials, for example, the following method
Therefore, a thermosensitive coloring layer used in the present invention is prepared. Immediately
First, a color-forming compound and a color-developing compound are
Binders or other additives as required
With ball mill, attritor, sand mill, etc.
After crushing and dispersing with a sprayer
Water is usually used as the medium), mixed and heat-sensitive coloring layer
Prepare a coating solution and use it on paper, plastic sheets, synthetic paper, etc.
Usually 1 to 20 g / m2 on dry weight ^TwoNana
Coating with a bar coater, blade coater, etc.
(The ratio of the coloring compound to the developing compound is usually the dry weight ratio.
2: 1 to 1:10) and may be dried.

An intermediate layer containing a colloidal inorganic silicate, a water-soluble polymer compound, and a hydrophobic polymer compound is provided on the thermosensitive coloring layer. In the present invention, the intermediate layer contains 5 to 70% by weight, more preferably 7 to 70% by weight of the colloidal inorganic silicate.
60%, water-soluble polymer compound is 5 to 75% by weight, more preferably 10 to 70%, and hydrophobic polymer compound is 20 to 8%.
5% by weight, more preferably 25-70%, other lubricants,
Surfactants, defoamers, benzophenone-based and triazole-based ultraviolet absorbers, fluorescent dyes, coloring dyes, and the like are each used at an arbitrary ratio, for example, 0 to 20% by weight, respectively. still,
The weight% is a weight ratio of each component in the intermediate layer.

The colloidal inorganic silicate used for the intermediate layer is a water-insoluble inorganic silicate and is a compound whose fine particles swell in water and can be dispersed on the colloid.
Colloidal aluminum silicate like bentonite, colloidal magnesium silicate like zepiolite, magnesium aluminum silicate like attapulgite,
Colloidal fluorinated magnesium silicate such as dimonite is exemplified. These colloidal inorganic silicates have a film forming ability.

As the water-soluble polymer compound, those which are generally used can be used, for example, an alkali salt of a copolymer of isobutylene / maleic anhydride / N-phenylmaleimide, polyvinyl alcohol, methyl cellulose, methoxy cellulose, hydroxy Ethylcellulose, carboxymethylcellulose, alkali salt of acrylic acid / styrene copolymer, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, alkali salt or ammonium salt of styrene-maleic anhydride copolymer, Iso (or diiso)
Examples include an alkali salt or an ammonium salt of a butylene-maleic anhydride copolymer, and an alkali salt or a polyvinyl alcohol of a copolymer of isobutylene / maleic anhydride / N-phenylmaleimide is particularly preferable for the intermediate layer of the present invention. .

The alkali salt of the copolymer of isobutylene / maleic anhydride / N-phenylmaleimide is exemplified by isobutylene / maleic anhydride / N-phenylmaleimide, for example, isobutylene: maleic anhydride: N-phenylmaleimide = 50: 5-30. : Copolymerized to a weight ratio of 45 to 20 to produce a product having a molecular weight of usually 20 to 80,000. The alkali salt of such a copolymer can be used as it is in the intermediate layer of the present invention. Examples of the alkali salt of the copolymer include a soda salt and an ammonium salt, and an ammonium salt is more preferable for the intermediate layer of the present invention.

As the polyvinyl alcohol, in addition to ordinary polyvinyl alcohol, modified polyvinyl alcohol such as carboxy-modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol and silica-modified polyvinyl alcohol can be used, but from the viewpoint of stability and the like, modified polyvinyl alcohol can be used. Unmodified polyvinyl alcohol is preferred for the intermediate layer of the present invention.

When these water-soluble polymer compounds are used in the intermediate layer of the present invention, a water-proofing agent is used in order to prevent background fog at the time of coating the overcoat layer and to improve the preservability of the obtained heat-sensitive recording material. Must be used to make it water resistant. Examples of the waterproofing agent include glyoxal, methylolmelamine, and a water-soluble epoxy compound. Examples of the water-soluble epoxy compound include ethylene polyethylene glycol diglycidyl ether, propylene polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, lauryl alcohol glycidyl ether, and the like. The amount of the waterproofing agent is usually 0.5 to 50% by weight, more preferably 1 to 30% by weight, based on the amount of the alkali salt of the copolymer.

Examples of the hydrophobic polymer compound used in the intermediate layer of the present invention include poly (meth) acrylate,
Acrylic high hydrophobicity such as styrene / (meth) acrylate copolymer, styrene / butadiene / (meth) acrylic acid copolymer, styrene / acrylonitrile / butadiene copolymer, ethylene / acrylic acid copolymer Molecular compounds, polystyrene, polyester, polyurethane,
Styrene-butadiene copolymer and the like are mentioned, and an acrylic hydrophobic polymer compound is preferable. These are used as emulsions.

The material for the intermediate layer of the present invention may be, if necessary, water or the like.
And mixers, attritors, sand mills, etc.
After thoroughly mixing with a conventional mixing stirrer,
ー, roll coater, gravure coater, air knife
Coating and drying on the thermal recording layer by a coating device such as a heater
Is done. The coating amount of the intermediate layer depends on the sensitivity of the obtained thermal recording medium.
Considering dryness, storage stability and whiteness of the skin, etc.
0.1 to 10 g / m^TwoIs good for images, etc.
In applications where uniformity is required, especially 0.5 to 3 g / m ^TwoIn
Preferably. Also, if necessary, after forming the intermediate layer
Calendar processing can also be performed.

In the heat-sensitive recording medium of the present invention, a radiation-curable overcoat layer is provided on the intermediate layer thus formed. The radiation-curable overcoat layer usually contains a monofunctional or polyfunctional monomer or oligomer as a main component, and optionally contains fillers, lubricants, surfactants, polymers, leveling agents, radically reactive silicone macromers, and defoamers. Agents, UV absorbers, antioxidants, polymerization inhibitors,
Contains additives such as antistatic agents and fluorescent dyes. Also,
In the case of curing by ultraviolet rays, a photopolymerization initiator and, if necessary, a photopolymerization accelerator are contained. In forming the overcoat layer in the present invention, a monofunctional or polyfunctional monomer or oligomer is 20 to 100% by weight, if necessary, a filler or a lubricant is 0.1 to 50% by weight. Foaming agents, ultraviolet absorbers and the like are each used at an arbitrary ratio, for example, 0 to 30% by weight, respectively. In the case of ultraviolet curing, the polymerization initiator and the accelerator are each 0.1 to 15% by weight.
To be included.

Examples of the monofunctional monomer include vinyl monomers such as styrene, vinyl acetate and N-vinylpyrrolidone, epoxy (meth) acrylate, saturated polyester / styrene, polyethylene (meth) acrylate, and the like.
Polyether (meth) acrylate, silicone (meth)
Acrylate, polybutadiene (meth) acrylate,
Oligomers such as polyene / thiol, polystyrylethyl (meth) acrylate, and polyamide (meth) acrylate; vinyl monomers such as styrene, vinyl acetate and N-vinylpyrrolidone; N, N-dimethylaminomethyl (meth) acrylate; -Dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, butyl (meth) acrylate,
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hydroxybutyl (meth)
Acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-decyl acrylate, isobornyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, nonylphenoxyethyl (Meth) acrylate, lauryl (meth) acrylate, phenylglycidyl ether (meth) acrylate, acryloylmorpholine, etc.

Examples of the polyfunctional monomer include ethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, and di (meth) acrylate of an alkylene oxide adduct of bisphenol A. ,
Tetraethylene glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate,
1,4-butanediol di (meth) acrylate, 1,
6-hexanediol di (meth) acrylate, 1,1
2-dodecanediol di (meth) acrylate, 1,1
4-tetradecanediol di (meth) acrylate,
1,16-hexadecanediol di (meth) acrylate, 1,20-eicosanediol di (meth) acrylate, isopentyldiol di (meth) acrylate,
Bifunctional monomers such as 3-ethyl-1,8-octanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethyloloctane tri (meth) acrylate, and trimethylolpropane polyethoxytri (meth) acrylate , Trimethylolpropane polypropoxytri (meth) acrylate,
Trimethylolpropane polyethoxypolypropoxytri (meth) acrylate, tris [(meth) acryloyloxyethyl] isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol polyethoxytetra (meth) acrylate, pentaerythritol polypropoxytetra ( Meth) acrylates,
Pentaerythritol tetra (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate,
Dipentaerythritol tetra (meth) acrylate,
Dipentaerythritol penta (meth) acrylate,
Dipentaerythritol hexa (meth) acrylate,
Examples include trifunctional or higher functional monomers such as caprolactone-modified tris [(meth) acryloyloxyethyl] isocyanurate.

Examples of the oligomer include epoxy (meth) acrylate, urethane (meth) acrylate, saturated polyester / styrene, polyethylene (meth) acrylate, polyether (meth) acrylate, silicon (meth) acrylate, polybutadiene (meth) acrylate, Polyene / thiol, polystyrylethyl (meth) acrylate, polyamide (meth) acrylate, and the like.

Examples of the filler include inorganic fillers such as aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, aluminum oxide, silicon dioxide, titanium dioxide, talc, clay, kaolin, colloidal silica, and metal powder. Fillers surface-treated with these inorganic fillers, styrene microballs, polystyrene resin beads, acrylic resin beads, urethane resin beads, polycarbonate resin beads, benzoguanamine-formalin condensate resin powder,
Benzoguanamine-melamine-formalin condensate resin powder, urea-formalin condensate resin powder, epoxy resin powder, polyethylene powder, tetrabromobisphenol A, decabromodiphenyl oxide, tricresyl phosphate, triethyl phosphate, aromatic polyester, etc. Organic fillers and the like can be mentioned. These fillers can be contained alone or in combination.

Examples of the lubricant include tetrafluoride resin, stearic acid-modified silicone oil, aspartic acid ester derivative, Famex A-1212 (manufactured by Ajinomoto Co.), polyethylene wax, carnauba wax, and the like.
Linear C16-C1 such as zinc stearate, magnesium stearate, calcium stearate, stearic amide, polyoxyethylene stearamide, polyoxyethylene sorbite stearic ester, etc.
Compounds having a long-chain alkyl group of 8, etc., can be mentioned, and these can be contained alone or in combination.

As a method of dispersing these fillers and lubricants in the radiation-curable resin, a generally known method of dispersing by means of a dispersing machine such as a ball mill, a roll mill, a sand mill and a dissolver can be used. Known filler dispersants such as polycarboxylic acid-based dispersants, silane coupling agents, titanate-based coupling agents, silicone-based dispersants such as modified silicone oils, and organic copolymer-based dispersants. It is also possible to use them together.

The radiation-curable resin composition used in the present invention may or may not be cured with an electron beam. However, when it is cured with an ultraviolet ray, a photopolymerization initiator may be used.
A photopolymerization accelerator is used. As the photopolymerization initiator, for example, acetophenone, benzophenone, benzoin ether, chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, α-aminoacetophenone, benzylmethylketal, thioxanthone, α-
Acyl oxime esters, acyl phosphine oxides, glyoxy esters, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, benzyl and the like can be mentioned. N-methyldiethanolamine, triethanolamine, diethanolamine, isoamyl P-dimethylaminobenzoate as a photopolymerization accelerator,
Known compounds such as amine compounds such as N, N-diethyl-P-aminobenzonitrile, phosphorus compounds such as tri-n-butylphosphine, chlorine compounds such as hexachloroethane, and Michler's ketone are used alone or in combination of two or more. Can also be used.

The radiation-curable resin composition used in the present invention may contain liquid paraffin, paraffin wax, polyethylene wax, synthetic wax, vegetable oil, animal oil, sorbitan ester, polyoxyethylene sorbite fatty acid ester, Glycerin fatty acid esters can be added. In addition, acrylic copolymer, silicone oil, silicone oil modified with alkyl group, amino group, epoxy group, fluorine group, carboxyl group, hydroxyl group, mercapto group, fluorine surfactant, polymer, leveling agent, radical reactivity Silicone macromers, defoamers, ultraviolet absorbers, antioxidants, polymerization inhibitors, antistatic agents, fluorescent dyes, and the like can be added.

The radiation-curable resin composition used in the present invention can be obtained by uniformly mixing the above components. The composition thus obtained is stable over time.

The radiation-curable resin composition thus obtained is coated on the intermediate layer by a conventional roll coater, bar coater, gravure coater, flexo coater, screen printing machine or the like by a method known per se, and a solvent is applied. In the case of dilution by, for example, application and drying, the coating film is cured by irradiating ultraviolet rays or electron beams. The coating amount of the overcoat layer is not particularly limited. However, if the dry weight is too small, the object of the present invention cannot be achieved.If the dry weight is too large, the recording sensitivity of the thermosensitive recording medium may decrease, or the coating weight may decrease. since there are cracks problem of the membrane, it is usually preferred as the dry weight 0.5 to 20 g / m ^2, more preferably 1 to 10 g / m ²
It is good to apply within the range. Examples of the radiation irradiation device include an electron beam acceleration device having an energy of 100 to 500 eV and an ultraviolet irradiation device having a xenon lamp, a high-pressure mercury lamp, and a metal halide lamp as a light source. The amount of light, the arrangement of the light source, and the like are determined depending on the device to be used.
With a lamp having a light amount of 0 W / cm, the transport speed is 20
It is preferred to cure by irradiating at 照射 60 m / min, 1 to 4 times.

[0039]

Example 1 Formation of heat-sensitive recording 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. . [A] solution: 3-dibutylamino-7- (o-chloroanilino) fluoran 25 parts 25% aqueous solution of PVA 20 parts water 55 parts [B] solution: 2,2-bis (p-hydroxyphenyl) propane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, each of the prepared solutions was mixed at the following ratio to prepare a coating solution for the heat-sensitive coloring layer.
24) The composition was coated so as to have a dry weight of about 10 g / m ² and dried to obtain a thermosensitive coloring layer. [A] solution 8 parts [B] solution 16 parts 50% calcium carbonate dispersion 20 parts 50% carboxylated styrene / butadiene copolymer latex 6 parts water 20 parts Formation of intermediate layer Styrene / 2-ethylhexyl acrylate / methyl methacrylate Polymerization emulsion (solid content 45%) 11 parts Ammonia salt aqueous solution of copolymer of isobutylene / maleic anhydride / N-phenylmaleimide (solid content 10%) 16 parts Colloidal aluminum silicate (Kunipia G; manufactured by Kunimine Industries) 1 Part water 72 parts The above composition was mixed to prepare a coating solution for an intermediate layer, and the dry coating amount was 1 g / m ² on the thermosensitive coloring layer obtained in the above.
And dried to obtain an intermediate layer.

Formation of Overcoat Layer Dipentaerythritol hexaacrylate 35 parts EO-modified bisphenol A diacrylate (KAYARAD R-551; manufactured by Nippon Kayaku) 6 parts 1,4-butanediol diacrylate 12 parts Calcium carbonate 40 parts Agent (Irgacure 184; Ciba Geigy) 7 parts After mixing the above compound, diluting with toluene, and applying a dry coating amount of 3 g / m on a middle layer obtained by using a bar coater.
Coated to ² and dried at 50 ° C drier, 80W
UV irradiator (GS A)
Conveyor speed 40 by SE-20 (manufactured by Nippon Battery)
The composition was cured by irradiating it twice at m / min to obtain a thermosensitive recording medium of the present invention.

Example 2 A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that an intermediate layer paint obtained by mixing the following compound in the intermediate layer was used. Acrylonitrile / acrylic acid copolymer emulsion (solid content 41%) 12 parts Polyvinyl alcohol aqueous solution 8 parts Colloidal aluminum silicate (Kunipia G; manufactured by Kunimine Industries) 1 part Water 79 parts

Comparative Example 1 A comparative thermosensitive recording medium was obtained in the same manner as in Example 1 except that the intermediate layer was prepared by mixing the following compounds in the intermediate layer. Acrylonitrile / acrylic acid copolymer emulsion (solid content 41%) 15 parts Ammonia salt aqueous solution of copolymer of isobutylene / maleic anhydride / N-phenylmaleimide (solid content 10%) 19 parts Water 66 parts

Tables 1 and 2 show the results of evaluation using each of the thus obtained thermosensitive recording media. Color development is performed using a commercially available video graphic printer (UP-860; SON).
Y Co., Ltd.) and evaluated. The following evaluation criteria were used.

Table 1 Evaluation Results Gloss Background Adhesion Coloring Density Uniformity of Coloring Head Matching Example 186 ○ ○ 〃 ○ 〃 284 ○ ○ ○ ○ ○ Comparative Example 1 80 × × × △ △

(1) Gloss The heat-sensitive recording medium was measured for its 60-degree specular gloss according to JIS Z8741. Gloss checker IG-320 for measurement
(Manufactured by Horiba, Ltd.) was used. (2) Background The background of the thermosensitive recording medium was visually determined. ；: Good without background fog ×: with background fog (3) Adhesion A peel test was performed with a cellophane tape to examine the adhesion between the intermediate layer and the overcoat layer. ；: No peeling ×: Peeling (4) Color density The color density of the printed portion was visually determined. ；: Good color development in the printed portion ×; insufficient color development in the printed portion (5) Uniform color development The uniformity of the color density in the intermediate color portion when the image was colored was visually determined. ○: uniform without roughness; ×: uneven with roughness (5) Head matching Print sound, scratches, image shrinkage during printing, streak-like uncolored portions that can be formed continuously (missing prints), head And head matching such as whitening after printing were determined. ；: Good △: usable level with some problem ×; problematic

[0047]

According to the present invention, in a thermosensitive recording medium in which a heat-sensitive coloring layer is provided on a support, and a radiation-curable overcoat layer is formed thereon via an intermediate layer, a colloidal inorganic silicate, By using a polymer compound and a hydrophobic polymer compound, a heat-sensitive recording material having high gloss, high-grade feeling, good adhesion, good head matching, little background fogging, and high color density was obtained. . Even if the thickness of the intermediate layer is reduced with emphasis on the uniformity of the colored image, the barrier property is high,
A good heat-sensitive recording material was obtained without background fouling during overcoat coating.

Claims (2)

[Claims] 1. A radiation-curable layer comprising a colorless or pale-colored color-forming compound and a color-developing compound capable of causing the color-forming compound to develop color when heated on a support. Wherein the intermediate layer comprises a colloidal inorganic silicate, a water-soluble polymer compound, and a hydrophobic polymer compound. 2. The heat-sensitive recording material according to claim 1, wherein the water-soluble polymer compound is an alkali salt of a copolymer of isobutylene / maleic anhydride / N-phenylmaleimide or polyvinyl alcohol.