JP2000071617A - Thermosensitive recording medium and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive recording medium having excellent surface glossiness, recording feedability, water resistance and alcohol resistance and a method for manufacturing it. SOLUTION: In the thermosensitive recording medium comprising a thermal recording layer containing a leuco dye, a colorant and an adhesive, a first intermediate layer containing aqueous resin, a second intermediate layer cured by illuminating an ionizing radiation to an ionizing radiation curable compound, and an uppermost layer containing a pigment and aqueous resin sequentially provided on a support; the uppermost layer contains aqueous resin obtained by seed polymerizing at least (meth)acylamide as a monomer. The method for manufacturing the medium comprises the steps of (1) sequentially providing a thermal recording layer and a first intermediate layer on a support, (2) coating the first layer with a coating liquid for the second layer containing the curable compound to provide a second intermediate coating surface, (3) providing an uppermost layer on a film or metal surface separate from the support, (4) bringing the uppermost layer into contact with the second coating surface, then (5) illuminating an ionizing radiation to cure the second intermediate layer, and (6) isolating the film or metal surface from the uppermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium utilizing a color-forming reaction between a leuco dye and a color former, and a method for producing the same.

[0002]

2. Description of the Related Art A thermosensitive recording medium having a thermosensitive recording layer containing a leuco dye, a coloring agent and an adhesive provided on one side of a support made of paper, synthetic paper, plastic film or the like is used as a recording medium. The recording device used is compact, inexpensive, and easy to maintain, so it can be used not only as a recording medium for facsimile machines, vending machines, and scientific measuring instruments, but also for various printers such as POS labels, CAD, and CRT medical images. Widely used as an output medium for plotters.

[0003] Among them, an image printer for CRT medical measurement that requires uniformity of recorded images and high resolution, and a CAD plotter that requires dimensional stability and thin line recording, synthetic paper having a multilayer structure, 2 containing inorganic pigments accordingly
An axially stretched thermoplastic resin film is used. With the diversification of uses, there is an increasing demand for a thermosensitive recording medium having excellent recording gradation, recording quality, and surface glossiness comparable to silver halide photography.

[0004] In order to obtain a thermosensitive recording medium having excellent surface gloss, a method of providing a second intermediate layer cured by irradiating an electron beam curable compound with an electron beam on a first intermediate layer containing an aqueous resin is known. Although described in JP-A-63-99984, a sufficient effect on the recording runnability and the surface gloss has not been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording medium having excellent surface gloss, recording running property, water resistance and alcohol resistance, and a method for producing the same.

[0006]

A heat-sensitive recording layer containing a leuco dye, a colorant and an adhesive, a first intermediate layer containing an aqueous resin, and an ionizing radiation-curable compound are irradiated with ionizing radiation on a support. In the heat-sensitive recording medium sequentially provided with the second intermediate layer hardened and cured, and the uppermost layer containing a pigment and an aqueous resin, a heat-sensitive recording medium having excellent surface gloss, recording running property, water resistance and alcohol resistance is obtained. As a means for providing the present invention, the present invention uses an aqueous resin obtained by seed-polymerizing at least (meth) acrylamide as a monomer as an aqueous resin in the uppermost layer.

Further, as a method for producing the above-mentioned thermosensitive recording medium,
In the present invention, a heat-sensitive recording layer and a first intermediate layer are sequentially provided on a support, and a second intermediate layer coating solution containing an ionizing radiation-curable compound is applied on the first intermediate layer to form a second intermediate layer. After providing the layer application surface, providing the uppermost layer on a film or a metal surface different from the support, and bringing the uppermost layer and the second intermediate layer application surface into close contact with each other, irradiating with ionizing radiation to cure the second intermediate layer , A film or a metal surface and the uppermost layer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A heat-sensitive recording layer containing a leuco dye, a coloring agent and an adhesive, a first intermediate layer containing an aqueous resin, and a second intermediate layer cured by irradiating an ionizing radiation-curable compound with ionizing radiation. Intermediate layer, and a thermosensitive recording medium sequentially provided with an uppermost layer containing a pigment and an aqueous resin, in the uppermost layer,
By containing at least an aqueous resin obtained by seed polymerization of (meth) acrylamide as a monomer (hereinafter, referred to as a specific seed polymerized resin), excellent glossiness of a recording portion and a background portion is obtained, and recording performance is improved. Thus, a heat-sensitive recording medium having excellent water resistance and alcohol resistance can be obtained.

[0009] The specific seed polymer resin contained in the uppermost layer is fine particles (0.5 to
3.0 × 10 ⁻⁸ m), that is, by drying a latex obtained by polymerizing (meth) acrylamide as a monomer at least around the seed particles.

The seed particles obtained by emulsion polymerization include, for example, (meth) acrylic ester type, styrene
(Meth) acrylate, (meth) acrylonitrile, styrene / butadiene, (meth) acrylonitrile / butadiene, (meth) acrylate
Fine particles made of a polymer such as butadiene, vinyl chloride, and vinyl acetate can be used. Such seed particles are:
They may be used alone or in combination of two or more. Among them, styrene / (meth) acrylic acid ester is preferable because an inexpensive and stable seed-polymerized aqueous resin can be obtained.

[0011] At least (meth) acrylamide is used as a monomer to be seed-polymerized around the seed particles. However, as long as the desired effects of the present invention are not impaired, copolymerization with (meth) acrylamide is possible. It is also possible to use a combination of other monomers capable of producing the same. Specific examples of such a monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- (meth) acrylate
Hydroxypropyl, 2-aminoethyl (meth) acrylate, 2- (N-methylamino) ethyl (meth) acrylate, 2- (N, N-dimethylamino) ethyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic esters such as glycidyl, vinyl esters such as vinyl acetate and vinyl propionate, nitrile group-containing monomers such as (meth) acrylonitrile, (meth) acrylic acid,
Unsaturated carboxylic acids such as maleic anhydride, fumaric acid, itaconic acid and crotonic acid; aromatic vinyl monomers such as styrene, α-methylstyrene and divinylbenzene;
N-substituted unsaturated carboxylic acid amides such as methylol (meth) acrylamide and the like. Among them, unsaturated monomers having a functional group such as a carboxyl group, a hydroxyl group, an amino group, a methylol group, and a glycidyl group are preferably used.

The amount of (meth) acrylamide used in the present invention is 5 to 100 parts by weight of the solid content of the seed particles.
３００300 parts by weight, preferably 10-100 parts by weight. If the amount of acrylamide is less than 5 parts by weight, sufficient heat resistance and solvent resistance cannot be obtained, and if it exceeds 500 parts by weight, the water resistance may decrease, and the viscosity of the specific seed polymerization latex may significantly increase. And a uniform top layer may not be obtained.

The content of the specific seed polymer resin in the uppermost layer is not particularly limited.
It is about 90% by weight, preferably about 15 to 70% by weight.
Furthermore, as long as the desired effects of the present invention are not impaired,
Various known other aqueous resins can also be used in combination. Specific examples of such other aqueous resins include, for example, completely (partially) saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, Starch, oxidized modified starch, casein, methylcellulose, polyacrylamide, styrene-acrylic acid copolymer salt, styrene-maleic anhydride copolymer salt, methyl vinyl ether-maleic anhydride copolymer salt, isopropylene- Water-soluble resins such as maleic anhydride copolymer salts, and water-dispersible resins such as vinyl acetate latex, acrylate resin latex, polyester polyurethane latex, and styrene butadiene latex are exemplified.

Specific examples of the pigment contained in the uppermost layer include kaolin, calcium carbonate, aluminum hydroxide, zinc oxide, barium sulfate, titanium oxide and amorphous silica. The ratio of the pigment and the aqueous resin in the uppermost layer is about 1: 9 to 9: 1 by weight.

The following auxiliaries can be added to the coating liquid for the uppermost layer in order to further improve the recording running property and the water resistance. Specific examples of such an auxiliary include calcium stearate, zinc stearate, barium stearate, paraffin wax, polyethylene wax, stearic acid amide, lubricants such as carnauba wax, glyoxal,
Dialdehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide-epichlorohydrin resin, melamine resin, diglycidyl compounds such as glycerin glycidyl ether, dimethylol urea compound, boric acid, etc. Crosslinking agents, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, surfactants such as salts of alkyl phosphate esters having 8 to 24 carbon atoms (potassium salts, sodium salts, ammonium salts); defoamers; fluorescent dyes And coloring dyes. As a surfactant, a salt of an alkyl phosphate having 8 to 24 carbon atoms is added in an amount of 0.1 to 5% by weight based on the total solid content of the uppermost layer, whereby a uniform uppermost layer without bird's eye can be obtained. It is formed.

The coating amount of the uppermost layer is not particularly limited.
About 0.5 to 5 g / m ² is preferable. If the amount is less than 0.5 g / m ² , sticking is likely to occur and the recording running property is deteriorated. If the amount exceeds 5 g / m ² , the sensitivity may decrease and the recording density may decrease.

According to the present invention, as a method for producing the above-mentioned thermosensitive recording medium, a thermosensitive recording layer and a first intermediate layer are sequentially provided on a support, and a second intermediate layer containing an ionizing radiation-curable compound is provided on the first intermediate layer. After applying the intermediate layer coating liquid to provide a second intermediate layer coating surface, providing the uppermost layer on a film or metal surface separate from the support, and bringing the uppermost layer into close contact with the second intermediate layer coating surface, Irradiating radiation to cure the second intermediate layer,
It separates between the film or metal surface and the top layer. A film or metal surface other than the support preferably has a 75 ° specular gloss of 60% or more, since the uppermost layer having excellent gloss can be obtained.

Specific examples of such a film include, for example, a polyester film, a polypropylene film, a polystyrene film, a polycarbonate film, and a nylon film having a thickness of 25 to 500 μm. There is a chrome-plated iron drum as a metal surface.

As the support in the present invention, for example, a polyolefin resin and a white inorganic pigment are heated and kneaded, extruded from a die, and stretched in the longitudinal direction. ~ 2 layers are laminated and stretched in the transverse direction to make it translucent or opaque, and synthetic paper, and a thermoplastic resin such as polyethylene, polypropylene, polystyrene, polyester alone or a mixture are heated and kneaded, and extruded from a die. Films obtained by axial stretching, opaque films obtained by mixing these resins with white inorganic pigments and biaxially stretching, and pulp fibers such as high quality paper, medium quality paper, neutral paper, recycled paper, and coated paper Can be used.

In the heat-sensitive recording layer formed on the support, various known leuco dyes and colorants can be used. Specific examples of such leuco dyes include, for example, 3,
3-bis [1- (4-methoxyphenyl) -1- (4-
Dimethylaminophenyl) ethylene-2-yl] -4,
5,6,7-tetrachlorophthalide, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di (n
-Butyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7- Anilinofluoran, 3-diethylamino-7- (m-trifluoromethyl) anilinofluoran, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluoran, 3
-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3-di (n-butyl) amino-7- (o-chloroanilino) fluoran, 3- (N
-Ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino)-
6-methyl-7- (p-toluidino) fluoran and the like. Of course, the present invention is not limited to these, and two or more of them can be used in combination as needed.

Specific examples of the coloring agent include, for example, 4,4 ′
-Isopropylidenediphenol, 4,4'-cyclohexylidenediphenol, 4-hydroxybenzoic acid benzyl ester, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 2,4'- Dihydroxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4-bis (phenylsulfonyl) phenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [Α-methyl-α- (4 ′
-Hydroxyphenyl) ethyl] benzene; thiourea compounds such as N, N'-di-m-chlorophenylthiourea; N- (p-tolylsulfonyl) carbamoyl p-cumylphenyl ester;
-(O-toluoyl) -p-trisulfonamide, N-
(P-trisulfonyl) -N ′-(p-tolyl) urea,
In a molecule such as 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane,
Those having a ₂ NH-bond, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, 4- [3
Zinc salts of aromatic carboxylic acids such as-(p-tolylsulfonyl) propyloxy] salicylate and 5- [p- (2- (p-methoxyphenoxyethoxy) cumyl] zinc salicylate. It is not limited, and two or more kinds can be used in combination as needed.

In the present invention, the ratio of the leuco dye to the color former in the heat-sensitive recording layer is appropriately selected according to the type of the leuco dye and the color former used, and is not particularly limited. Generally, it is preferable to use 1 to 10 parts by weight, preferably about 1 to 5 parts by weight of a coloring agent per 1 part by weight of the leuco dye.

If necessary, the following sensitizers and storage improvers can be added to the heat-sensitive recording layer. Specific examples of the sensitizer include, for example, stearamide, behenamide, dibenzyl terephthalate, dibenzyl oxalate, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, Dibutyl isophthalate, 2-naphthylbenzyl ether, 1,2-di (m-tolyloxy) ethane, 1,2-diphenoxyethane, 1-phenoxy-2
-(Β-naphthoxy) ethane, diphenyl carbonate, p-benzylbiphenyl and the like.

As the preservability improver, for example, 2,2'-
Methylene bis (4-methyl-6-tert-butylphenol), 4,4′-butyldenbis (6-tert-butylphenol)
Butyl-m-cresol), 1,1,3-tris (2-
Methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 2,
2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6
-Tert-butylphenol) and ultraviolet absorbers such as 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole and 2-hydroxy-4-octyloxybenzophenone. In general, it is preferable that the sensitizer and the storage stability improver are each contained in an amount of about 0.1 to 4 parts by weight based on 1 part by weight of the leuco dye.

The heat-sensitive recording layer is formed, for example, by using water as a dispersion medium.
Leuco dye, color former and, if necessary, sensitizer by pulverizer such as sand mill, attritor and ball mill,
After pulverizing together or separately with a preservative improver,
The coating liquid for a heat-sensitive recording layer prepared by adding an adhesive or the like is coated on a support at a coating amount of about 3 to 20 g / m ² after drying, followed by drying. The adhesive used in the heat-sensitive recording layer can be appropriately selected and used from those of the aqueous resin used in the uppermost layer. The amount of the adhesive used in the heat-sensitive recording layer is preferably about 8 to 35 parts by weight based on the solid content of the heat-sensitive recording layer.

The coating solution for the heat-sensitive recording layer is applied onto a support by a method conventionally used by those skilled in the art, such as an offset gravure method, an air knife method, a Meyer bar method, a blade method, a reverse roll method, and a slit die method. You.

In the heat-sensitive recording medium of the present invention, in order to prevent background fogging of the heat-sensitive recording layer and to improve the preservability of a recorded image, a first intermediate containing an aqueous resin is first provided on the heat-sensitive recording layer thus obtained. A layer is provided. The aqueous resin used for the first intermediate layer can be appropriately selected from those used for the heat-sensitive recording layer, and among these, completely (partially) saponified polyvinyl alcohol having excellent film-forming properties, Silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol and casein are preferred. The first intermediate layer has a coating amount of 1 to 1 after drying the first intermediate layer coating liquid in which the aqueous resin is dissolved or dispersed on the heat-sensitive recording layer.
It is preferable to apply and dry so as to have a weight of about 7 g / m ² . The coating liquid for the first intermediate layer is applied in the same manner as the above-mentioned coating liquid for the heat-sensitive recording layer.

When the coating amount of the first intermediate layer is less than 1 g / m ² , there is a problem that the coating film is not formed uniformly, so that the barrier property is lowered. When it exceeds 7 g / m ² , the sensitivity is lowered and the recording density is lowered. May decrease. The amount of the aqueous resin used in the first intermediate layer is not particularly limited, but may be 2 to the solid content of the intermediate layer in terms of excellent barrier sensitivity and recording sensitivity.
About 0 to 80% by weight is preferable. Thermal recording layer and first
In the coating liquid for the intermediate layer, pigments, lubricants, crosslinking agents, surfactants and the like can be appropriately selected and used from those used for the uppermost layer, if necessary.

By subjecting the surface of the first intermediate layer of the present invention to a smoothing treatment using a super calender, a gloss calender, a machine calender, or the like, the coatability of the second intermediate layer is improved, and the second intermediate layer having a uniform thickness is formed. Layers can be formed.

The coating amount of the second intermediate layer formed on the first intermediate layer is not particularly limited, but is about 1 to 10 g / m ² . If the coating amount is less than 1 g / m ^2, the glossiness of the uppermost layer may decrease, or the recording quality may decrease, and if it exceeds 10 g / m ² , the recording sensitivity may decrease. The second intermediate layer is formed by applying a coating liquid for a second intermediate layer containing an ionizing radiation-curable compound on the first intermediate layer to provide a second intermediate layer coated surface, and then forming a film or a film separate from the support. By bringing the uppermost layer formed on the metal surface into close contact with the second intermediate layer application surface and emitting ionizing radiation, the second intermediate layer application surface is cured and formed.

Specific examples of the ionizing radiation curable compound used in the second intermediate layer include electron beam curable compounds such as acrylate or methacrylate monomers or oligomers having one or more ethylenically unsaturated bonds. For example, monofunctional monomers include N-vinylpyrrolidone, acrylonitrile or its derivatives, styrene or its derivatives, amide group-containing monomers such as acrylamide, benzyl acrylate,
Ethylhexyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate, ε-caprolactone adduct acrylate, butoxyethyl (meth) acrylate, 2-
Hydroxy-3-phenoxypropyl acrylate, cyclohexyl (meth) acrylate, N, N-dimethylamino (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, 3-phenoxypropyl acrylate, 2-methoxyethyl (meth) And (meth) acrylates such as acrylate.

Examples of the monomer having two or more ethylenically unsaturated bonds include hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, and tricyclodecane dimethylol diacrylate. Examples thereof include acrylate, trimethylolpropanetetraacrylate, dipentaerythritol hexa (penta) acrylate, ε-caprolactone-modified dipentaerythritol acrylate, and ethylene oxide-modified bisphenol A diacrylate. These compounds having one or more ethylenically unsaturated bonds may be used as a mixture of two or more as necessary.

The (meth) acrylate oligomer having one or more ethylenically unsaturated bonds includes, for example, one or more urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, butadiene-modified (meth) acrylate oligomers, and the like. May be used in combination.

As a method for preparing the coating solution for the second intermediate layer, a three-roll mill, a two-roll mill, a Cowles dissolver, a homomixer, a sand mill, a paint conditioner, an ultrasonic disperser, or the like can be used.
Further, the method of applying the coating liquid for the second intermediate layer onto the first intermediate layer may be a conventional method such as offset gravure method, air knife method, Meyer bar method, blade method, reverse roll method, slit die method, etc. A system used by those skilled in the art can be used to apply the coating liquid on the support.

The electron beam accelerator used for the electron beam irradiation is not particularly limited, and for example, an electron beam irradiation apparatus such as an electro-curtain system or a scanning system can be used. Among them, an electro-curtain type which is relatively inexpensive and can obtain a large output is effectively used. The accelerating voltage at the time of electron beam irradiation is preferably 100 KV or more, and the absorbed dose is preferably as small as possible within a sufficient range from the viewpoint of minimizing damage to the support.

[0036]

The present invention will be described in detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

Example 1 Preparation of Solution A A composition comprising 20 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 5 parts of a 10% aqueous solution of polyvinyl alcohol, and 20 parts of water was prepared by using Ultra. Disperse with a viscomil so that the average particle size becomes 1.3 μm.
A liquid was obtained.

Solution B Preparation A composition comprising 50 parts of 4-hydroxy-4′-isopropoxydiphenylsulfone, 5 parts of a 10% aqueous solution of polyvinyl alcohol, and 70 parts of water is made to have an average particle size of 1.3 μm by ultraviscomil. Liquid B was obtained as described above.

Preparation of coating solution for heat-sensitive recording layer 30 parts of solution A, 90 parts of solution B, 52 parts of 60% slurry of calcium carbonate, 40% aqueous solution of polyvinyl alcohol 40
Part, styrene-butadiene latex (trade name: L-
1537, solid content 50%, 28 parts by Asahi Kasei Co., Ltd., 11 parts of stearamide (trade name: Himicron G-270, solid concentration 20%, manufactured by Chukyo Yushi Co., Ltd.), zinc stearate (trade name: Hydrin Z- 7-30, solid concentration 30
%, Manufactured by Chukyo Yushi Co., Ltd.) and 82 parts of water were mixed and stirred to obtain a coating solution for a heat-sensitive recording layer.

Preparation of Coating Solution for First Intermediate Layer Kaolin (trade name: UW-90, manufactured by Engelhard Co.)
70% 60% slurry, zinc stearate (trade name:
15 parts of hydrin Z-7-30, solid concentration 30%, manufactured by Chukyo Yushi Co., Ltd., 180 parts of a 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol (trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and A composition comprising 120 parts of water was mixed and stirred to obtain a first intermediate layer coating liquid.

Preparation of Coating Solution for Second Intermediate Layer As an electron beam-curable compound, 80 parts of acrylate of ε-caprolactone-modified dipentaerythritol (trade name: Kayarad DPCA-60, manufactured by Nippon Kayaku Co., Ltd.), 1 part of ethylene oxide-modified , 6-hexanediol diacrylate (trade name: Kayarad R-167, manufactured by Nippon Kayaku Co., Ltd.) 2
0 parts were mixed and stirred to obtain a second intermediate layer coating liquid.

Preparation of Coating Liquid for Top Layer Seed particles obtained by emulsion-copolymerizing a monomer composed of 60 parts of styrene, 38 parts of 2-ethylhexyl acrylate and 2 parts of acrylic acid (particle diameter: about 2 × 10 ^-8 m), 175 parts of a latex having a solid concentration of 20% obtained by subjecting 10 parts of acrylamide and 10 parts of methacrylamide to seed polymerization,
Kaolin (trade name: UW-90, manufactured by Engelhard)
100 parts of a 60% slurry of potassium stearyl phosphate (trade name: Woopol 1800, solid concentration 3
5%, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 10 parts, 10 parts of a 5% aqueous solution of sodium salt of dioctylsulfosuccinic acid and water 150
Were mixed and stirred to obtain a coating liquid for the uppermost layer.

Preparation of heat-sensitive recording medium Synthetic paper (trade name: YUPO FPG-80, Oji Yuka Synthetic Paper Co., Ltd.)
Coating solution for the heat-sensitive recording layer and the coating for the first intermediate layer
The coating amount of each liquid after drying was 8.0 g / m. ^Two3.
0 g / m^TwoAnd then apply and dry with a bar coating method
After forming the heat-sensitive recording layer and the first intermediate layer,
-Calendar treatment, and then a coating liquid for the second intermediate layer
3.5 g / m^TwoApply the second intermediate
The layer coating surface was formed. Separately, 75μm thick PE
T film (trade name: Lumirror T, manufactured by Toray)
The coating amount after drying the upper layer coating solution is 1.0 g / m^TwoWill be
After coating and drying with a bar coating method,
The upper layer is brought into close contact with the
Acceleration voltage of 1 using an electron beam accelerator (manufactured by ESI)
Irradiate 75KV, 3.0Mrad of absorbed electron beam
After curing the second intermediate layer, the PET film and the top layer
Was peeled off to obtain a thermosensitive recording medium.

Example 2 In the preparation of the coating solution for the uppermost layer in Example 1, acrylic acid 2
A thermosensitive recording medium was obtained in the same manner as in Example 1, except that 38 parts of butyl acrylate was used instead of 38 parts of -ethylhexyl.

Example 3 In the preparation of the coating solution for the uppermost layer in Example 1, 175 parts of a latex having a solid concentration of 20% obtained by seed polymerization was replaced by a latex having a solid concentration of 20% obtained by seed polymerization. 100 parts and polyvinyl alcohol (trade name:
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 50 parts of a 10% aqueous solution of PVA-117 (manufactured by Kuraray Co., Ltd.) was used.

Example 4 In the production of the thermal recording medium of Example 1, synthetic paper (commodity
Name: One side of Yupo FPG-80, manufactured by Oji Yuka Synthetic Paper)
Then, the coating solution for the heat-sensitive recording layer and the coating solution for the first intermediate layer are
The coating weight after drying is 8.0 g / m^Two3.0 g / m^Two
It is applied by a bar coating method and dried in order to obtain
After forming the recording layer and the first intermediate layer, the super calendar
-The amount of the second intermediate layer coating solution
3.5 g / m ^TwoAnd apply the second intermediate layer coating surface
Formed. Separately, mirror-plated gold plated with chrome
The coating amount after drying the coating liquid for the uppermost layer is 1.0
g / m ^TwoOffset gravure coating method so that
After drying the cloth, bring the second intermediate layer coating surface and the uppermost layer into close contact with each other,
Electro-curtain type electron beam from the side opposite to the metal drum surface
Acceleration voltage 175KV, absorption by accelerator (manufactured by ESI)
The second intermediate layer is hardened by irradiating an electron beam with a dose of 3.0 Mrad.
After heat treatment, heat is applied by separating between the metal drum and the top layer.
A recording was obtained. Each coating solution was used to prepare the thermosensitive recording medium of Example 1.
What was used in was used.

Comparative Example 1 In the preparation of the coating solution for the uppermost layer in Example 1, instead of 175 parts of latex having a solid concentration of 20% obtained by seed polymerization, styrene / butadiene latex having a solid concentration of 48% (commercially available) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 73 parts of L-1571 (manufactured by Asahi Kasei Corporation) and 3 parts of polypropylene glycol having a molecular weight of about 2,000 were used as a release agent.

Comparative Example 2 In the preparation of the coating liquid for the uppermost layer in Example 1, instead of 175 parts of latex having a solid concentration of 20% obtained by seed polymerization, 15% of a graft polymer of polyvinyl alcohol and polyacrylamide was used. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 230 parts of a 30% aqueous solution was used.

Comparative Example 3 In the preparation of the coating liquid for the uppermost layer in Example 1, instead of 175 parts of latex having a solid concentration of 20% obtained by seed polymerization, a polyurethane-based latex having a solid concentration of 35% (trade name: A thermosensitive recording medium was obtained in the same manner as in Example 1, except that 100 parts of Diamond Beam NR-0355 (manufactured by Mitsubishi Rayon Co., Ltd.) was used.

Comparative Example 4 In the production of the thermosensitive recording medium of Example 1, synthetic paper (commodity
Name: One side of Yupo FPG-80, manufactured by Oji Yuka Synthetic Paper)
Then, the coating solution for the heat-sensitive recording layer and the coating solution for the first intermediate layer are
The coating weight after drying is 8.0 g / m^Two3.0 g / m^Two
It is applied by a bar coating method and dried in order to obtain
After forming the recording layer and the first intermediate layer, the super calendar
-The amount of the second intermediate layer coating solution
3.5 g / m ^TwoAnd apply the second intermediate layer coating surface
Formed. Electro-curtain type electron beam accelerator (ESI
Acceleration voltage 175KV, absorbed dose 3.0Mr
Irradiation of ad electron beam to cure the second intermediate layer and heat-sensitive recording
I got a body. Each coating solution was used to prepare the thermosensitive recording medium of Example 1.
Was used.

The following evaluation tests were performed on each of the thus obtained heat-sensitive recording media, and the results are shown in Table 1. [Gloss (Surface Gloss)] Gloss Meter (Product Name: GM-26
D, Murakami Color Research Laboratory) at an incident angle of 75 degrees.

[Recording density and sticking resistance (recording running property)] Thermal printer (trade name: UP-880,
Sony Corporation) and measure the density of the recording part in the visual mode of a Macbeth densitometer (trade name: 914 type, manufactured by Macbeth), and determine the intensity of the sticking sound generated during recording as follows. did. [Evaluation Criteria] ：: There is almost no sticking noise, and there is no problem in the recording traveling property. ：: There is a little sticking sound, but there is no problem in the recording running property. ：: The sticking sound is a little strong, and the recording running property is slightly poor. X: Sticking sound is strong and recording traveling performance is poor.

[Water resistance] One drop of water is dropped on the uppermost layer,
After one minute, the surface of the heat-sensitive recording medium after wiping was observed. [Judgment Criteria] A: No change in uppermost layer. ：: The uppermost layer is slightly whitened. Δ: The uppermost layer swelled slightly and was partially detached from the recording medium. X: The protective layer swelled and completely detached from the recording medium.

[Alcohol resistance] One drop of ethanol was dropped on the heat-sensitive recording medium, and after 1 minute, the surface of the recording medium when wiped off was observed. [Judgment Criteria] A: No change in uppermost layer. ：: The uppermost layer is slightly whitened. Δ: The uppermost layer swelled slightly and was partially detached from the recording medium. X: The protective layer swelled and completely detached from the recording medium.

[0055]

[Table 1]

[0056]

As is clear from the results shown in Table 1, the present invention relates to a heat-sensitive recording medium having excellent surface gloss, recording running property, water resistance and alcohol resistance, and a method for producing the same.

Claims (2)

[Claims] 1. A heat-sensitive recording layer containing a leuco dye, a colorant and an adhesive, a first intermediate layer containing an aqueous resin, and an ionizing radiation-curable compound which is cured by irradiating ionizing radiation on a support. In a thermosensitive recording medium provided with a second intermediate layer and an uppermost layer containing a pigment and an aqueous resin in order, the aqueous resin in the uppermost layer was obtained by seed polymerization of at least (meth) acrylamide as a monomer. A heat-sensitive recording material characterized by being a resin. 2. A heat-sensitive recording layer containing a leuco dye, a coloring agent and an adhesive, a first intermediate layer containing an aqueous resin, and an ionizing radiation-curable compound which is cured by irradiating ionizing radiation on a support. A second intermediate layer, and a method for producing a thermosensitive recording medium in which a top layer containing a pigment and an aqueous resin are sequentially provided.
A heat-sensitive recording layer and a first intermediate layer are sequentially provided on a support, and a coating liquid for a second intermediate layer containing an ionizing radiation-curable compound is applied on the first intermediate layer to form a coating surface of the second intermediate layer. After providing the uppermost layer on a film or metal surface different from the support, and bringing the uppermost layer into close contact with the second intermediate layer application surface,
The method for producing a thermosensitive recording medium according to claim 1, wherein the second intermediate layer is cured by irradiating with ionizing radiation, and the film or the metal surface is separated from the uppermost layer.