JPH10329425A - Thermal recording medium and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium having excellent recording feeding property and surface glossiness and a method for manufacturing the medium with excellent productivity. SOLUTION: In the thermal recording medium comprising a thermal recording layer containing leuco dye, colorant and adhesive, first intermediate layer containing aqueous resin, second intermediate layer containing hydrophobic resin and uppermost layer containing pigment and aqueous resin sequentially provided on a support, as means for obtaining the medium having excellent recording feeding property and surface glossiness, as hydrophobic resin of the second intermediate layer, resin cured by emitting electron beam after ultraviolet ray is emitted to ionizing radiation curable compound at the time of forming the second intermediate layer is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color former, and more particularly to a heat-sensitive recording material excellent in recording runnability and surface gloss, 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 machines, but also for various printers such as POS labels, CAD, and CRT medical images. -Widely used as output media for plotters.

Among them, an image printer for CRT medical measurement requiring uniformity of recorded images and high resolution, and a CAD plotter requiring dimensional stability and fine line recording, such as synthetic paper having a multilayer structure, A biaxially stretched thermoplastic resin film containing an inorganic pigment is used in accordance with (1). 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, such a second intermediate layer has a problem that sticking easily occurs during recording.

In order to solve such a problem, the present inventors have found a thermosensitive recording medium (JP-A-7-125430) in which an uppermost layer containing a pigment and a resin is further provided on a second intermediate layer. When the uppermost layer is peeled off from a glossy polyester film or metal surface to increase the surface gloss, the operation speed may be increased if the peelability between the film or metal surface and the uppermost layer is not sufficient. It needs to be limited, and there is a problem with productivity. In particular, a polyester film has a higher adhesion to the uppermost layer resin than a chromed iron drum surface, and thus has a problem that the operating speed is significantly restricted.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermosensitive recording medium having excellent recording running properties and surface gloss, and a method for producing the thermosensitive recording medium having excellent productivity.

[0007]

A thermosensitive 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 containing a hydrophobic resin are provided on a support. As a means for obtaining a heat-sensitive recording medium having excellent recording runnability and surface glossiness in a heat-sensitive recording medium provided with a top layer containing a pigment and an aqueous resin in order, When forming the second intermediate layer as a conductive resin,
A resin cured by irradiating the ionizing radiation-curable compound with ultraviolet rays and further irradiating with an electron beam is used. Further, on the support, a heat-sensitive recording layer containing a leuco dye, a colorant and an adhesive, a first intermediate layer containing an aqueous resin, and a second layer cured by irradiating the ionizing radiation-curable compound with an electron beam. An intermediate layer, and a method for manufacturing a thermosensitive recording medium in which a top layer containing a pigment and an aqueous resin is sequentially provided, as a means of a method for manufacturing a thermosensitive recording medium having excellent recording runnability and surface gloss, and excellent productivity. In the present invention, 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 a photopolymerization initiator and an ionizing radiation-curable compound is provided on the first intermediate layer. The coating was applied to provide a second intermediate layer application surface, the uppermost layer was provided on a film different from the support, the uppermost layer was brought into close contact with the second intermediate layer application surface, and ultraviolet light was irradiated from the back side of the support or the film. After that, the second intermediate layer is cured by further irradiating an electron beam, It is to peeling between the light film and the top layer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The second intermediate layer containing an ionizing radiation-curable compound further contains a photopolymerization initiator, and is irradiated with ultraviolet rays to pre-cur the second intermediate layer, thereby forming the uppermost layer. The uppermost layer can be easily peeled off from the film to be formed, and a heat-sensitive recording material having excellent glossiness in a recording portion and a background portion can be obtained.

Examples of the photopolymerization initiator include, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzoin octyl ether, anthraquinone, benzophenone, 2-methylanthraquinone, methyl orthobenzoylbenzoate, diacetyl , Dibenzyltriphenylphosphine, azobisisobutylnitrile and the like. These photopolymerization initiators can be used alone, or can be used in combination of two or more as needed.

The amount of the ionizing radiation curable compound and the photopolymerization initiator used is usually 0.1 to 15% by weight, preferably 0.5 to 5% by weight of the photopolymerization initiator per 100 parts by weight of the ionizing radiation curable compound. Although it is desirable to be about weight%, it can be appropriately determined in consideration of the intensity of the ultraviolet ray to be irradiated and the irradiation time. Also, as a light source for UV irradiation,
1 to 50 ultraviolet lamps, xenon lamps, tungsten lamps and the like are used, and ultraviolet rays having an intensity of about 30 to 160 W / cm are preferably irradiated.

The coating amount of the second intermediate layer is not particularly limited, but is about 1 to 10 g / m ² . The coating amount is 1 g / m ²
If it is less than the above, the glossiness of the uppermost layer may decrease, or the recording quality and the adhesion between the uppermost layer and the second intermediate layer may decrease. If it exceeds 10 g / m ² , the recording sensitivity may decrease. is there. The second intermediate layer is prepared by applying a coating liquid for a second intermediate layer containing an ionizing radiation-curable compound and a photopolymerization initiator to the first intermediate layer.
After coating on the intermediate layer to provide a second intermediate layer coating surface, the uppermost layer formed on a film different from the support is brought into close contact with the second intermediate layer coating surface, irradiated with ultraviolet rays, and further ionized. By irradiating the radiation, the second intermediate layer application surface is cured and formed, so that either the support or the film is preferably transparent.

Examples of the ionizing radiation-curable compound used in the second intermediate layer include ionizing radiation-curable compounds such as acrylate or methacrylate monomers or oligomers having one or more ethylenically unsaturated bonds. As a monofunctional monomer, for example, N-
Vinylpyrrolidone, acrylonitrile or derivatives thereof, styrene or derivatives thereof, 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 include acrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexa (penta) acrylate, acrylate of ε-caprolactone-modified dipentaerythritol, and diacrylate of ethylene oxide-modified bisphenol A. These compounds having one or more ethylenically unsaturated bonds may be used as a mixture of two or more as necessary.

Examples of the (meth) acrylate oligomer having one or more ethylenically unsaturated bonds include urethane (meth) acrylate oligomer, polyester (meth) acrylate oligomer, and butadiene-modified (meth) acrylate oligomer.

As a method for preparing the coating liquid 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.
Examples of the method of applying the coating liquid for the second intermediate layer on the first intermediate layer include an offset gravure method, an air knife method, a Meyer bar method, a blade method, a reverse roll method, and a slit die method.

The electron beam accelerator used for 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. Acceleration voltage for electron beam irradiation is 100KV
Preferably, the absorbed dose is as small as possible within a sufficient range from the viewpoint of minimizing damage to the support.

As the support in the present invention, for example, a polyolefin-based resin and a white inorganic pigment are heated and kneaded, extruded from a die and stretched in the longitudinal direction, and a film made of the polyolefin-based resin and the white inorganic pigment is coated on both sides at one side. ~ 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.

As for the combination of the leuco dye and the color former contained in the heat-sensitive recording layer, various known leuco dyes and color formers 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-dimethylamino-7-chloroanilinofluoran, 3- [N-ethyl- N- (p-methylphenyl) amino] -6-methyl-7-anilinofluoran, 3-diethylamino-7- (m-trifluoromethyl) anilinofluoran, 3- (N-ethyl-N-tetrahydro Furfuryl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isopentyl) amino-6
-Methyl-7-anilinofluoran, 3-di (n-butyl) amino-7- (o-chloroanilino) fluoran and the like. Of course, the present invention is not limited to these, and two or more kinds may be used in combination. The amount of the leuco dye contained in the heat-sensitive recording layer is 0.1 to 3 g / m ^2.
Degree is used.

Specific examples of the coloring agent include, for example, 4,4 ′
-Isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl sulfone,
-Hydroxy-4'-isopropoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4-hydroxyphenyl) ethyl] benzene, 2,2′-thiobis (4-tert- Phenolic compounds such as octylphenol), thiourea compounds such as N, N'-di-m-chlorophenylthiourea, N- (p-tolylsulfonyl) carbamoyl p-cumylphenyl ester, N
-(O-toluoyl) -p-trisulfonamide, N-
In a molecule such as (p-tolylsulfonyl) -N '-(p-tolyl) urea and 4,4'-bis (N-p-tolylsulfonylaminocarbonylamino) diphenylmethane,
Having a SO ₂ NH— bond, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate,
Zinc salts of aromatic carboxylic acids such as [3- (p-tolylsulfonyl) propyloxy] zinc salicylate and 5- [p- (2- (p-methoxyphenoxyethoxy) cumyl] zinc salicylate. It is not limited to these colorants, and two or more colorants can be used in combination. The colorant is 1 to 5 parts by weight, particularly about 1.5 to 3 parts by weight, per 1 part by weight of the leuco dye. It is preferred to use.

In the heat-sensitive recording layer, if necessary, the following sensitizers and storage improvers can be added.
Specific examples of the sensitizer include, for example, stearic acid amide,
Behenic acid amide, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di-p-methylbenzyl ester, oxalic acid di-p-chlorobenzyl ester, isophthalic acid dibutyl ester, 2-naphthyl benzyl ether, 1,2 -Di (3-methylphenoxy)
Examples include ethane, 1,2-diphenoxyethane, 1-phenoxy-2- (4-methylphenoxy) ethane, diphenyl carbonate, p-benzylbiphenyl, and the like.

As the preservability improver, for example, 2,2'-
Methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-
Butyl-3-methylphenol), 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-ter)
t-butylphenol), 2,4-di-tert-butyl-3-methylphenol, 4,4′-thiobis (3-
Hindered phenols such as methyl-6-tert-butylphenol), 2- (2′-hydroxy-5′-
UV absorbers such as methylphenyl) -benzotriazole and 2-hydroxy-4-benzyloxybenzophenone. The sensitizer and the storage stability improver
In general, it is preferable to contain about 0.1 to 4 parts by weight with respect to 1 part by weight of the leuco dye.

The heat-sensitive recording layer is formed, for example, by using water as a dispersion medium.
The average particle diameter is adjusted to about 0.2 to 3.0 μm by a pulverizer such as a sand mill, an attritor and a cobol mill together or separately with a leuco dye, a color former, and, if necessary, a sensitizer and a preservability improver. After finely dispersing, it is formed by applying and drying a coating solution for a heat-sensitive recording layer prepared by incorporating an adhesive on a support so that the coated amount after drying is about 3 to ²⁰ g / m ² .

Specific examples of the adhesive contained in the coating solution for the heat-sensitive recording layer include, for example, completely (partially) saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-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- Use water-soluble resin such as maleic anhydride copolymer salt, and water-dispersible resin such as vinyl acetate latex, acrylate resin latex, polyester polyurethane latex, styrene-butadiene latex, alone or in combination Can do Kill. The amount of the adhesive used in the heat-sensitive recording layer is preferably 8 to 35% by weight based on the solid content of the heat-sensitive recording layer.

Further, in the coating solution for the heat-sensitive recording layer, kaolin, calcium carbonate, aluminum hydroxide, zinc oxide,
Pigments such as barium sulfate, titanium oxide, amorphous silica,
Lubricants such as zinc stearate and calcium stearate; waxes such as polyethylene wax and paraffin wax; surfactants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, acetylene glycol, and phosphate esters; and coloring dyes, fluorescent dyes, A fluorescent pigment or the like can be added.

The coating solution for the heat-sensitive recording layer is applied to the 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.

The heat-sensitive recording medium of the present invention has a first intermediate containing an aqueous resin on the heat-sensitive recording layer thus obtained in order to prevent background fog of the heat-sensitive recording layer and to improve the preservability of the recorded image. 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 . As a coating method, a method similar to the method used for coating the heat-sensitive recording layer can be used.

If 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 and the barrier property is reduced. If it exceeds 7 g / m ² , the sensitivity is lowered and the recording density is reduced. May drop. The amount of the aqueous resin used in the first intermediate layer is not particularly limited, but is 2% based on the solid content of the first intermediate layer in that the recording sensitivity and the recording sensitivity are excellent.
0 to 80% by weight is preferred. In the first intermediate layer coating liquid, pigments, lubricants, surfactants and the like can be appropriately selected and used from those used for the heat-sensitive recording 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 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 traveling property is deteriorated. If the amount exceeds 5 g / m ² , the sensitivity may decrease, and the recording density may decrease.

The ratio of the pigment and the aqueous resin in the uppermost layer is
The weight ratio is about 10:90 to 90:10. In the coating liquid for the uppermost layer, a lubricant, a surfactant, a cross-linking agent, and the like are appropriately selected from those used for the heat-sensitive recording layer or the first intermediate layer in order to further enhance the recording runnability, water resistance, and the like. Can be used.

Specific examples of the aqueous resin contained in the uppermost layer include, for example, completely (partially) saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, starch, and oxidized modified starch. , Casein, methylcellulose, polyacrylamide, styrene-acrylic acid copolymer salt, styrene-maleic anhydride copolymer salt, methyl vinyl ether-maleic anhydride copolymer salt, isopropylene-maleic anhydride copolymer Water-soluble resins such as coalesced salts, and vinyl acetate latex,
Water-dispersible resins such as acrylate resin-based latex, polyurethane-based latex, and styrene-butadiene-based latex are exemplified.

Further, specific examples of the pigment include kaolin, calcium carbonate, aluminum hydroxide, zinc oxide, barium sulfate, titanium oxide, amorphous silica and the like.

Further, the uppermost layer is polyethylene wax,
A wax such as paraffin wax, a surfactant such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, acetylene glycol, and phosphate ester, a coloring dye, a fluorescent dye, and the like can also be added.

In the coating solution for the uppermost layer, the heat-sensitive recording layer and the first intermediate layer, if necessary, a dialdehyde compound such as glyoxal or dialdehyde starch, a polyamine compound such as polyethyleneimine, an epoxy compound, or a polyamide -Diglycidyl compounds such as epichlorohydrin resin, melamine resin, glycerin glycidyl ether,
A crosslinking agent such as a dimethylol urea compound, an aziridine compound, a block isocyanate compound, ammonium persulfate, magnesium chloride, sodium tetraborate, potassium tetraborate, and boric acid can also be added.

[0035]

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. Parts and% are parts by weight and% by weight, respectively, unless otherwise specified.
Is shown.

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 dispersed with an Ultraviscomiler such that the average particle diameter became 1.3 μm, to obtain a liquid A.

[Preparation of Solution B] 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 was treated with an ultra-viscomil to have an average particle size of 1.3 μm. To obtain a liquid B.

[Preparation of coating solution for heat-sensitive recording layer]
Liquid 90 parts, calcium carbonate 60% slurry 52 parts, polyvinyl alcohol 10% aqueous solution 40 parts, styrene-
Butadiene latex (L-1537, solid concentration 50
%, Asahi Kasei Kogyo Co., Ltd.) 28 parts, stearic acid amide (Cerozole A-877, solid concentration 26.5%, manufactured by Chukyo Yushi Co., Ltd.) 11 parts, zinc stearate (hydrin Z-7-)
30, a solid concentration of 30%, a composition comprising 13 parts of Chukyo Yushi Co., Ltd.) and 82 parts of water were mixed and stirred to obtain a coating liquid for a heat-sensitive recording layer.

[Preparation of Coating Solution for First Intermediate Layer] 100 parts of an 8% aqueous solution of polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.), 10 parts of calcium carbonate (Softon 1800, manufactured by Bihoku Powder Chemical Co., Ltd.) and 10 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 ionizing radiation-curable compound, acrylate of ε-caprolactone-modified dipentaerythritol (Kayarad DPCA-6)
0, 80 parts, Nippon Kayaku Co., Ltd.) 80 parts, diacrylate of diglycidyl ether of 1,6-hexanediol (Kayarad R-167, Nippon Kayaku Co., Ltd.) 20 parts and benzophenone (Kayacure BP, Nippon Kayaku Co., Ltd.) The mixture was mixed and stirred with 0.5 part to obtain a second intermediate layer coating liquid.

[Preparation of Coating Liquid for Top Layer] Kaolin (UW-
90, manufactured by Engelhard Co.)
Parts, 100 parts of polyurethane latex (UE-1101, solid concentration 35%, manufactured by Toagosei Co., Ltd.), 10 parts of stearyl phosphate potassium salt (Upol 1800, solid concentration 35%, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and 30 parts of water Was mixed and stirred to obtain a coating liquid for the uppermost layer.

[Preparation of Coating Solution for Back Layer] 30 parts of a 30% aqueous solution of sodium polystyrene sulfonate (Chemistat SA-9, manufactured by Sanyo Chemical Industries, Ltd.), styrene-butadiene latex (L-1537, solid concentration 50%, 70 parts of Asahi Kasei Kogyo Co., Ltd., 150 parts of a 10% aqueous solution of oxidized starch (Ace A, manufactured by Oji Cornstarch), kaolin (UW-
90, manufactured by Engelhard Co.) and a composition comprising 67 parts of a 60% slurry and 83 parts of water were mixed and stirred to obtain a coating liquid for a back layer.

[Preparation of Thermosensitive Recording Material] The coating amount after drying the back layer coating solution on one surface (back side) of a commercially available synthetic paper (Yupo FPG-80, manufactured by Oji Yuka Synthetic Paper) was 1 0.5 g / m
As a ² by coating and drying a bar coating method to form a back layer, the coating amount after drying, respectively a thermal recording layer coating solution and the first intermediate layer coating solution on the other surface (surface side) Is 5.5
g / m ² , 1.5 g / m ² to form a heat-sensitive recording layer and a first intermediate layer by successive coating and drying with a bar coating method.
It was applied by a bar coating method so that the coating amount of the coating liquid for the intermediate layer was 3.5 g / m ² to form the second intermediate layer coated surface. Separately, a 75 μm thick PET film (Lumirror T,
The coating amount after drying the uppermost layer coating solution is 1.0
g / m ² after coating and drying using a bar coating method.
Immediately after the intermediate layer application surface and the uppermost layer are brought into close contact with each other and irradiated with a 60 W / cm high-pressure mercury lamp from the PET film side at a height of 30 cm for 5 seconds from the PET film side and precured, an electron curtain type ionizing radiation accelerator (manufactured by ESI) ) Accelerating voltage 175KV, absorbed dose under PET film 3.0Mr
After the second intermediate layer was cured by irradiation with ionizing radiation of ad, the PET film and the uppermost layer were separated to obtain a thermosensitive recording medium. The obtained heat-sensitive recording material had good releasability from the PET film, and no pits were missing in the uppermost layer.

Example 2 In the preparation of the coating solution for the uppermost layer in Example 1, 2-hydroxy-2-methyl-propiophenone (Tokyo) was used instead of 0.5 part of benzophenone (Kayacure BP, manufactured by Nippon Kayaku Co., Ltd.). A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 5 parts of the product were used (manufactured by Kasei Kogyo Co., Ltd.). As in Example 1, the obtained heat-sensitive recording material had good releasability from the PET film, and no pits were missing in the uppermost layer.

Comparative Example 1 The procedure of Example 1 was repeated, except that no photopolymerization initiator was added and no ultraviolet light was applied in the preparation of the coating solution for the uppermost layer of Example 1.
In the same manner as in the above, a thermosensitive recording medium was obtained. The obtained heat-sensitive recording material had poor releasability from the PET film, and the uppermost layer was finely scattered on the PET film after peeling and removal, and pits were missing in the uppermost layer.

[0046]

As described above, the present invention relates to a thermosensitive recording medium having excellent recording running properties and surface gloss, and a method for producing the thermosensitive recording medium having excellent productivity.

Claims (2)

[Claims] 1. A thermosensitive recording layer containing a leuco dye, a color former and an adhesive, a first intermediate layer containing an aqueous resin, a second intermediate layer containing a hydrophobic resin, and a pigment on a support. In a thermosensitive recording medium in which an uppermost layer containing an aqueous resin is sequentially provided, the ionizing radiation-curable compound is irradiated with ultraviolet rays and then further irradiated with an electron beam when the hydrophobic resin contained in the second intermediate layer is formed in the second intermediate layer. A heat-sensitive recording material, which is a resin cured by heating. 2. A thermosensitive 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 are cured by irradiating an electron beam 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 is sequentially provided, wherein a thermosensitive recording layer and a first intermediate layer are sequentially provided on a support,
On the first intermediate layer, a coating liquid for a second intermediate layer containing a photopolymerization initiator and an ionizing radiation-curable compound is applied to provide a second intermediate layer application surface, and the second intermediate layer is coated on a film different from the support. An upper layer is provided, the uppermost layer is brought into close contact with the surface to which the second intermediate layer is applied, and after irradiating ultraviolet rays from the back side of the support or the film, the second intermediate layer is further irradiated with an electron beam to cure the film and the uppermost layer. And a method for producing a thermosensitive recording medium.