JPH0811430A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having high gloss and mapping properties, imparting good image quality and having excellent printing characteristics by setting the Young's modulus of the film of the inside coating layer constituting the gloss layer laminated on a base material to a specific value. CONSTITUTION:A thermal color forming layer is provided on at least a single surface of a base material and an intermediate layer is provided on the thermal color forming layer, if necessary, and a gloss layer is provided on the thermal color forming layer or the intermediate layer to form a thermal recording material. In this case, the gloss layer is constituted of an outside coating layer containing white pigment and an unsaturated org. compd. cured by the irradiation with electron beam and an inside coating layer based on an unsaturated org. compd. cured by the irradiation with an electron beam. In the thermal recording material obtained by peeling the outside coating layer from a molding surface having high smoothness, the Young's modulus of the film of the inside coating layer is 50kg/mm<2> or more at 20 deg.C. As a concrete example of the unsaturated org. compd., there is N-vinyl pyrrolidone, acrylonitrile or a derivative thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording material. More specifically, the present invention is capable of providing a recorded image having good image quality, high gloss and image clarity, and also having excellent print characteristics.

[0002]

2. Description of the Related Art A thermal recording material is generally a paper, a synthetic paper, a plastic film or the like on one side of a support.
A thermosensitive coloring layer containing a colorless or pale color-forming substance such as an electron-donating leuco dye, an organic acid developer such as an electron-accepting phenol compound, and an adhesive as main components It is possible to obtain a color recorded image by reacting the color forming dye and the color developing agent with heat energy. Such a thermal recording medium has advantages such as a compact recording apparatus, low cost, and easy maintenance, and is not only used as a recording medium for a facsimile, an automatic ticket vending machine, or a scientific measuring machine, POS label, CA
Various printers and plotters for D, CRT medical images, etc.
It is widely used as an output medium.

Among them, image printers for CRT medical measurement, which require uniformity of recorded images and high resolution, and CAD plotters, which require dimensional stability and fine line recording, require synthetic paper having a multi-layer structure and necessary. According to the above, a biaxially stretched thermoplastic resin film containing an inorganic pigment is used. On the other hand, high-value-added thermosensitive recording materials such as video printers and papers are required to have high gloss and image clarity in addition to high image quality. However, in order to have high gloss and image clarity in addition to image quality such as uniformity and resolution of the recorded image, it is necessary to make the outermost surface layer of the thermal recording medium highly smooth in addition to the texture of the base material, cushioning property, and the like. is there.

In order to make the outermost surface layer of the thermosensitive recording medium highly smooth, for example, there is a method of using a coating material which is cured by ultraviolet rays or electron beams as proposed in Japanese Patent Laid-Open No. 62-279980. However, in this method, since a ripple pattern is generated on the surface due to shrinkage during curing, high image clarity cannot be obtained even if high gloss is obtained, and quality is insufficient. As a result of extensive studies on such problems, the present inventors have found that when a glossy layer is provided on a thermosensitive recording medium, a coating containing an unsaturated organic compound that can be cured by electron beam irradiation as a main component is heat-sensitive to a base material. When the coloring layer or the intermediate layer is provided on the thermosensitive coloring layer, it is coated on the intermediate layer and pressure-bonded to the molding surface having a high smooth surface, and then cured by an electron beam, or on the molding surface. When the base material thermosensitive coloring layer or the intermediate layer is provided on the thermosensitive coloring layer by coating the coating material, after being bonded to the intermediate layer, it is cured by an electron beam,
After that, by peeling off the molding surface, the high smoothness of the molding surface is transferred to the surface of the gloss layer cured by the electron beam, and there is no ripple pattern due to curing shrinkage, and high gloss and image clarity are imparted. It was found that this was possible, and the application was filed as Japanese Patent Application No. 5-202039.

However, if the outermost surface layer of the thermal recording medium is made highly smooth, the contact area between the outermost surface layer and the thermal recording head increases, so that the running trace of the thermal recording head or the thermal recording head scrapes the outermost surface layer. In addition to the marked printing defects caused by the adhesion of shavings to the thermal recording head, the thermal recording head and the outermost surface layer tend to stick to each other when the humidity is high, resulting in poor running and high smoothness. A technical problem was pointed out.

[0006] Therefore, as a solution to the problem, the present inventors have found that a gloss layer contains an outer coating layer containing a white pigment and a specific amount of an unsaturated organic compound which can be cured by electron beam irradiation and an outer coating layer which can be cured by electron beam irradiation. A method has been found which consists of an inner coating layer containing a saturated organic compound as a main component, and the outer coating layer is peeled off from a molding surface having high smoothness.
No. 1552 was filed. However, as described above, by adding a specific amount of a white pigment and an unsaturated organic compound that can be cured by electron beam irradiation to the outer coating layer, it is possible to improve the hardness and toughness of the cured coating film. Problems such as obstacles and poor running were still insufficient, and improvements were needed.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of conventional thermal recording materials, has high gloss and image clarity, and also has excellent image quality and excellent printing characteristics. Is provided.

[0008]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that an inner coating layer containing an unsaturated organic compound which can be cured by electron beam irradiation as a main component is formed. It was found that when the physical properties of the coating film, particularly the Young's modulus of the coating film is in a specific range or more, in addition to having good image quality, high gloss and image clarity, a thermal recording material having excellent printing characteristics can be obtained, The present invention has been completed.

That is, according to the present invention, a thermosensitive coloring layer is provided on at least one side of a substrate, an intermediate layer is optionally provided on the thermosensitive coloring layer, and then the thermosensitive coloring layer or the intermediate layer is formed. The gloss layer comprises a white pigment and an outer coating layer containing an unsaturated organic compound curable by electron beam irradiation, and an inner coating layer containing an unsaturated organic compound curable by electron beam irradiation as a main component, and The outer coating layer is a thermosensitive recording medium obtained by peeling from the molding surface having high smoothness, and the Young's modulus of the coating film of the inner coating layer is 50 K at a temperature of 20 ° C.
It is a thermosensitive recording medium characterized by having g / mm ² or more.

The base material used in the present invention is obtained by heat-kneading a polyolefin resin and a white inorganic pigment, extruding from a die, and stretching in the machine direction. ~ 2
Synthetic paper produced by laminating layers and stretching in the transverse direction to make them translucent or opaque, and thermoplastic resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, polyvinyl chloride, polystyrene, polyester, etc. Is a film obtained by heat-kneading the mixture and extruding it from a die and biaxially stretching it, and a biaxially stretched opaque film obtained by mixing these resins with a white inorganic pigment.
Those manufactured from pulp fibers such as medium-quality paper, roll paper, recycled paper and coated paper can be used. In order to improve the uniformity of the image, the support made of pulp fibers is preferably provided with a coating layer in advance and then coated with a heat sensitive layer.

The thermosensitive coloring layer of the present invention contains a colorless or light-colored electron-donating leuco dye, an organic acidic substance that causes the leuco dye to develop a color by heating, and an adhesive as main components, and, if necessary, a crosslinking agent, It can be provided by applying a thermosensitive coloring layer coating material to which a pigment and a thermoplastic substance are added. The coating amount of the heat-sensitive color forming layer is generally preferably 3 to 15 g / m ^{2 in} terms of color forming sensitivity and color forming density. As a coating method, an air knife method, a Meyer bar method, a blade method, a reverse roll method, a slit die method, or the like which has been conventionally used by those skilled in the art can be used. Further, the surface of the thermosensitive coloring layer is subjected to a smoothing treatment with a super calendar, a gloss calendar, a machine calendar or the like to improve the coatability and the recording density and sensitivity.

As the color-forming dye, a colorless or light-colored electron-donating leuco dye capable of developing a color by reacting with a developer under heating is used. The color forming dye used in the present invention is, for example, 2,2 bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro (phthalide-3,9'-xanthene) -2. '-Ilamido] phenyl} propane, 3-diethylamino-6methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-methyl-N)
-Cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-dimethylamino-7-chloroanilinofluorane, 3- [N-ethyl-N- (p-methylphenyl) amino] -6-methyl -7-anilinofluorane, 3-diethylamino-7- (metatrifluoromethyl) anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane , 3- (N-ethyl-N-isopentyl)
Amino-6-methyl-7-anilinofluorane, 3-
It is composed of at least one member of a fluorane dye such as (N, N dibutyl) amino-6-methyl-7-anilinofluorane.

The color developer used in the present invention is composed of an electron-accepting organic acidic substance capable of reacting with a color-forming dye under heating to form a color. Such a color developer liquefies or vaporizes at room temperature or higher, preferably 70 ° C. or higher, and reacts with the color-forming dye to develop a color thereof. In order to maximize the color density, the color developer is usually used in a proportion of 1 to 5 parts by weight, preferably 1.5 to 3 parts by weight, based on 1 part by weight of the color forming dye.

Examples of the color developer include 4,4'-isopropylidenediphenol (bisphenol A) and 4,4'-
Isopropylidene bis (2-chlorophenol), 4,
4'-isopropylidene bis (2-methylpheno-
), 4,4'-isopropylidene bis (2,6-t-
Butylphenol), 4,4'-sec-butylidene diphenol, 4,4'-cyclohexylidene diphenol
, 4-t-butylphenol, 4-phenylphenol
, 4-hydroxydiphenoxide, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 3,3'-dihydroxydiphenyl sulfone, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone Resulfone, 3,3'-diallyl-4,4 '
-Dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfone, 4-
Hydroxydiphenyl sulfone, 4-hydroxy-4 '
-Isopropyloxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 2,
4-dihydroxydiphenyl sulfone, 2,4-dihydroxy-4'-methyldiphenyl sulfone, and 3,
It is composed of at least one member selected from 4-dihydroxyphenyl-p-trisulfone and the like.

In the present invention, both the water-soluble resin and the water-dispersible resin can be used as the adhesive contained in the thermosensitive coloring layer. For example, polyvinyl alcohol, starch, modified starch, acacia, gelatin, casein, chitosan, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyacrylic acid salt, polyacrylic amide, polyester resin, styrene-acrylic acid ester Polymerization resin, styrene-maleic anhydride copolymer resin, methyl vinyl ether-maleic anhydride copolymer resin, water-soluble resin such as isopropylene-maleic anhydride copolymer resin, and vinyl acetate emulsion, acrylic ester copolymer emulsion, Methacrylic acid ester copolymer emulsion, polyurethane emulsion, polyvinyl chloride emulsion, S
An emulsion such as BR latex or MBR latex having a minimum film-forming temperature of 20 ° C. or less and having good film-forming property can be used alone or in combination.

However, it is necessary that the mixed liquid does not develop color, aggregate, or become highly viscous when mixed with the respective dispersion liquids of the above-mentioned color-forming dye and color-developing agent. The thermal recording layer film is tough,
It is necessary that there is no desensitizing effect. The content of the adhesive in the thermosensitive coloring layer is preferably 8 to 20% with respect to the solid content of the thermosensitive coloring layer.
If it exceeds 0%, there is a problem that the sensitivity decreases.

Further, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for curing the resin can be used. For example, glyoxal, dialdehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins,
Melamine resins, diglycidyl compounds such as glyceryl glycidyl ether, dimethylol urea compounds, aziridine compounds, block isocyanate compounds, ammonium persulfate and ferric chloride, and magnesium chloride, sodium tetraborate, potassium tetraborate. Inorganic compounds such as boric acid, boric acid triester, and boron-based polymer can be used in the range of 1 to 10% with respect to the solid content of the thermosensitive coloring layer.

As the pigment, a fine particle pigment having a high whiteness and an average particle diameter of 5 μm or less can be used in order to improve the whiteness of the thermosensitive coloring layer and the uniformity of an image. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated calcium carbonate and silica. Inorganic pigments such as, and urea-formalin resin,
Organic pigments such as styrene-methacrylic acid copolymer resin and polystyrene resin can be used. The amount of the pigment blended is 40% with respect to the solid content of the thermosensitive coloring layer in order not to reduce the coloring density.
% Or less is desirable.

Examples of the thermoplastic substance include fatty acid amides such as stearic acid amide, stearic acid bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide and behenic acid amide, zinc stearate, calcium stearate, polyethylene wax, and the like. Waxes (or lubricants) such as carnauba wax, paraffin wax, ester wax, terephthalic acid dimethyl ester, terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, isophthalic acid dibutyl ester, 1-
Hydroxynaphthoic acid phenyl ester, 1,2-di (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1-phenoxy-2- (4-methylphenoxy) ethane, diphenyl carbonate, p-benzylbiphenyl, 2 , 2'-methylenebis (4-methyl-6-t-
Butylphenol), 4,4'-butylidene bis (6-
t-butyl-3-methylphenol), 1,1,3 tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 2,2'-methylenebis (4-ethyl-)
Hindered phenol such as 6-t-butylphenol), 2,4-di-t-butyl-3-methylphenol and 4,4'-thiobis (3-methyl-6-t-butylphenol). , 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, and 2-hydroxy-
There are sensitizers such as 4-benzyloxybenzophenone, antioxidants, and ultraviolet absorbers.

Generally, the thermoplastic substance is preferably contained in the thermosensitive coloring layer in a ratio of 4 parts by weight or less with respect to 1 part by weight of the color developer. Further, in order to improve the wetting of the heat-sensitive color developing layer coating and eliminate cissing, it is possible to add a wetting improver such as acetylene glycol or dialkylsulfosuccinate, a pigment dispersant, a defoaming agent, a fluorescent dye, a coloring pigment, or the like. it can.

The thermosensitive recording material of the present invention has a gloss layer and thermosensitive coloring.
Adhesion with layers, coating of glossy layer, prevention of background color development during curing, etc.
Therefore, it is possible to provide an intermediate layer between the thermosensitive coloring layer and the gloss layer.
It is effective. In this case, water-soluble and / or
Contains water-dispersible resin, pigment, lubricant and crosslinking agent as main components
The coating amount after drying the coating material has 1.0 to 5.0 g / m ²
It can be obtained by coating so that The coating amount is 1.
0 g / m²If less than, the coating film was not formed uniformly
Therefore, there are pinholes and coating defects, resulting in poor image quality and surface quality.
It causes it to go down. Coating amount is 5.0g / m²Crossing
There is a drawback that the sensitivity is lowered and the print density is reduced. How to coat
For the formula, the same method as used for coating the thermosensitive coloring layer can be used.
Can be used.

The surface of the intermediate layer is a super calendar,
By performing a smoothing treatment with a gloss calender, a machine calender, etc., it is possible to enhance the coating property of the gloss layer and improve the recording density, sensitivity and gloss. The resin of the intermediate layer is 20 to 80% with respect to the solid content of the intermediate layer, and the pigment is 20 to 80%.
The range of 80% is good, and if the compounding ratio of the resin exceeds 80%, there is a problem that sticking occurs during recording. Also,
When the compounding ratio of the resin is less than 20%, a paint having a low barrier property of the coating film and causing background coloration has insufficient ability to prevent the paint from penetrating, and the effect of improving the adhesiveness between the heat-sensitive color forming layer and the gloss layer also decreases.

The inner coating layer forming the gloss layer of the present invention is a coating material containing an unsaturated organic compound which is hardened by electron beam irradiation as a main component, and the Young's modulus of the physical properties of the coating film at a temperature of 20 ° C. , 50 Kg / mm ² or more is desirable, and the coating amount after drying is 1.0 to 10.0 g / m ^2.
It can be obtained by coating so that Young's modulus is 5
When it is 0 kg / mm ² or more, the cause of improvement in running defects and the like is not clear, but it is considered that the deformation of the glossy layer by the thermal recording head is reduced. Coating amount is 1
If it exceeds 0.0 g / m ² , the sensitivity is lowered, and even if it is dealt with by increasing the coating amount of the thermosensitive coloring layer, the printing density is lowered. When the coating amount is less than 1.0 g / m ² , peeling from the molding surface of the outer coating layer containing a high content of white pigment required for the inner coating layer coating and adhesion with the thermosensitive coloring layer or the intermediate layer are prevented. Hard to achieve enough.

The unsaturated organic compound which is hardened by electron beam irradiation and which is used in the coating layer for the inner coating layer for forming the gloss layer of the present invention is 50 kg / mm ^{2 at} a temperature of 20 ° C.
There is no particular limitation as long as it is a resin having the above Young's modulus,
For example, N-vinylpyrrolidone, acrylonitrile or a derivative thereof, styrene or a derivative thereof, an amide group-containing monomer such as acrylamide, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl (meth) acrylate. , 2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate, ε-caprolactone adduct acrylate, butoxyethyl (meth) Acryle
, 2-hydroxy-3-phenoxypropyl acrylate, cyclohexyl (meth) acrylate, N, N-
Dimethylamino (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, 3-phenoxypropyl acrylate, 2-methoxyethyl (meth) acrylate, polyoxyethylene epichlorohydrin-modified bisphenol A Diacrylate, dicyclohexyl acrylate, epichlorohydrin modified polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, hydroxybivalic acid ester neopentyl glycol diacrylate, nonylphenoxy polyethylene glycol acrylate, ethylene oxide modified phenoxyphosphoric acid acrylate, polybutadiene acrylate , Caprolactone-modified tetrahydrofurfuryl acrylate, tris (acryloxyethyl) isocyanate, tri Tyrole propane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, polyethylene glycol diacrylate, 1,4-butadiene diol diacrylate, neopentyl glycol diacrylate, and neopentyl glycol modified trimethylolpropane diacrylate Acrylate and the like can be used alone or in combination of two or more.

Among them, a trifunctional or higher functional resin having a high cross-linking property and a caprolactone-modified dipentaerythritol hexa (penta) acrylate, ethylene oxide-modified trimethylolpropane triacrylate, dipentaerythritol hexa (penta) acrylate, etc. having a compounding ratio of 20%. It is desirable to mix the above. 20% compounding ratio
When it is less than 1, the Young's modulus is less than 50 kg / mm ² , and the effect of improving running defects cannot be obtained.

The white pigment compounded in the coating material for the inner coating layer forming the glossy layer of the present invention is used to improve the hardness and whiteness of the glossy layer,
A fine particle pigment having a high whiteness and an average particle size of 5 μm or less can be used because of a reduction in printing troubles and running defects.
For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide,
Aluminum hydroxide, barium sulfate, inorganic pigments such as surface-treated calcium carbonate and silica, and urea-
Formalin resin, styrene-methacrylic acid copolymer resin,
Organic pigments such as polystyrene resin can be used.

To disperse the white pigment in an unsaturated organic compound which is cured by electron beam irradiation, a three roll mill,
A two-roll mill, cowles dissolver, homomixer, sand grinder, paint conditioner, ultrasonic disperser and the like can be used. Further, the coating method of the inner coating layer paint can use 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. . The outer coating layer forming the glossy layer of the present invention comprises a white pigment (A) and an unsaturated organic compound (B) curable by electron beam irradiation in a weight ratio of A / B of 40/60 to 95 /. The coating amount after drying the coating material containing the main component in the ratio of 5 is 1.0 to 1
It can be obtained by coating so that the amount becomes 0.0 g / m ² . If the coating amount exceeds 10.0 g / m ² , the sensitivity will decrease,
Even if it is dealt with by increasing the coating amount of the thermosensitive coloring layer, there is a drawback that the printing density becomes low. When the coating amount is less than 1.0 g / m ² , it is difficult to obtain high image clarity and glossiness in addition to the poor releasability from the molding surface after curing.

The amount of the white pigment is preferably as large as possible from the viewpoint of increasing the hardness of the cured coating film, but in order to obtain good releasability from the molding surface and high surface property of the cured coating film,
The weight ratio of A / B is preferably 95/5 or less. Further, in order to obtain a desired hardness, the weight ratio of A / B is preferably 40/60 or more.

The white pigment compounded in the coating material for the outer coating layer for forming the glossy layer of the present invention can be appropriately selected and used from those used in the coating material for the inner coating layer. The unsaturated organic compound which is hardened by an electron beam and is mixed in the coating material for the outer coating layer which forms the glossy layer of the present invention includes an acrylate or methacrylate monomer having one or more ethylenically unsaturated bonds, or One kind or a mixture of two or more kinds of oligomers and the like can be used, and in order to obtain the required toughness, a mixture containing an oligomer as a main component is desirable.

Examples of the acrylate or methacrylate oligomer having one or more ethylenically unsaturated bond include, for example, one or more of urethane acrylate oligomer, polyester acrylate oligomer, butadiene modified acrylate oligomer and the like. May be mixed and used. If the viscosity of the above-mentioned monomer having an ethylenically unsaturated bond, a white pigment dispersed in an oligomer is high, a solution diluted with an organic solvent is dried after coating,
Alternatively, it is effective to use it by emulsifying it for easy handling, or if it is water-soluble, replace it with one diluted with water, dry after coating, and then cure by electron beam.

Although a polymer soluble in these compositions may be added to the electron beam-curable composition of the present invention, if the amount of the polymer added is too large, the curability of the coating film decreases. It is not preferable in terms of scratch resistance and organic solvent resistance. A non-reactive lubricant having no ethylenically unsaturated bond can be used if necessary, but like other non-reactive substances, it is desirable to mix it in such a range that the decrease in curability does not pose a problem.

The non-reactive lubricant used in the coating material for the outer coating layer which forms the gloss layer includes waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax.
Alkyl phosphates and alkali metal salts such as lauryl phosphates, oleyl phosphates and stearyl phosphates, or amine salts, alkyl sulfonates such as lauryl sulfonates, olein sulfonates, stearyl sulfonates and alkalis Metal salts or amine salts, glyceryl monomyristate, glyceryl monostearate, glyceryl monostearate, glyceryl monostearate, glyceryl distearate, glyceryl fatty acid esters such as glyceryl dioleate, diglyceryl monolaurate, diglyceryl dilaurate, tetralauryl monolaurate Polyglycerin fatty acid ester such as glyceryl, hexalauryl monolaurate, decaglyceryl monolaurate, dimethylpolysiloxane and various modified products thereof There, desensitizing effect from the, color erasing action, it is necessary to select those without background color action.

As a method of pressure-bonding the outer coating layer and the inner coating layer for forming the electron beam curable glossy layer of the present invention and then curing and integrating them by electron beam irradiation, a molding surface having high smoothness is formed. A method of press-bonding the coated outer coating layer and the inner coating layer coated on the thermosensitive coloring layer or the intermediate layer, and irradiating with an electron beam from the opposite surface of the thermosensitive recording material or the molding surface side to cure it, Coating the inner coating layer directly on the outer coating layer coated on the molding surface having high smoothness, and then press-bonding with the thermosensitive coloring layer or the intermediate layer, or from the opposite surface of the thermosensitive recording medium or molding There is a method of curing by irradiating an electron beam from the surface side.
The latter method can be carried out in the same manner as the former method as long as the viscosity of the inner coating layer is high and the penetration into the outer coating layer is small.

The surface of the gloss layer formed as described above has high smoothness and exhibits high gloss and image clarity. Specifically, the 75-degree gloss specified by JIS-Z-8714 is 8
0% or more, and 80% or more, preferably 90% or more, when the value when the width of the optical comb of 2 mm of the image sharpness specified by JIS-K-7105 is used as a scale of image clarity. It is desirable to indicate the value of.

[0035]

The present invention will be described in more detail with reference to the following examples, but the invention is not limited thereto. Unless otherwise specified, parts and% indicate parts by weight and% by weight, respectively. Example 1 Commercially available synthetic paper (manufactured by Oji Yuka Synthetic Paper, trademark: YUPO FPG-
80) The thermosensitive coloring layer coating shown below was applied on one side by a bar coating method so that the coating amount after drying was 5.5 g / m ^2, and the intermediate layer coating was dried on it. Coating amount of 1.5g /
After coating so as to have a m ² thickness, an inner coating layer coating for forming a gloss layer is further coated thereon at 3.0 g / m ² to form an inner coating layer. Separately from this, a 75 μm PET film (Toray (Trademark: Lumira-T), an outer coating layer is applied onto the outer coating layer so as to have a coating amount after drying of 3.0 g / m ² to form an outer coating layer. The inner coating layer is pressure-bonded to form a gloss layer composed of an outer coating layer and an inner coating layer, and PET.
The gloss layer is cured and integrated by irradiating an electron beam with an accelerating voltage of 175 KV and an absorbed dose of 3.0 Mrad under the PET film from the film side using an electron-curtain type electron beam accelerator (manufactured by ESI), and the PET film after curing. Was peeled from the glossy layer to obtain a thermosensitive recording medium.

Preparation of coating material for thermosensitive coloring layer Liquid A (thermosensitive coloring dye dispersion) 3- (N, N-dibutyl) amino-6-methyl-7-anilinofluorane 20 parts 10% polyvinyl alcohol aqueous solution 20 Part Water 10 parts Solution B (developer developer dispersion) 4-Hydroxy-4'-isopropyloxydiphenyl sulfone 50 parts 10% aqueous polyvinyl alcohol solution 50 parts Water 25 parts Solution A and solution B are separately separated with Ultraviscomill. It was dispersed and pulverized, and adjusted so that the average particle diameter was 1.0 ± 0.3 μm. Liquid A 30 parts, liquid B 90 parts, 60% calcium carbonate slurry 52 parts, 10% polyvinyl alcohol aqueous solution 40 parts, SBR latex (solid content 50%,
Asahi Kasei, trademark: L-1537) 28 parts, stearic acid amide (solid content 26.5%, Chukyo Yushi Co., Ltd., trade name: Cerosol A-877) 11 parts, and water 82 parts were mixed to obtain a thermosensitive coloring layer coating material.

・ Interlayer paint (solid content 15%) 60% Kaolinite clay (average particle size 0.6 μm) dispersion 42 parts Carboxylic acid modified polyvinyl alcohol aqueous solution (solid content 10%) (Nippon Gosei Kagaku Co., Ltd.) Made, trademark: Gohsenal T-330) 200 parts Acrylic emulsion (solid content 40%, manufactured by Nippon Shokubai Co., Ltd., trademark: SC-2250) 100 parts Dimethylol urea solution (solid content 30%, Showa Denko KK) (Trade name: J-001) 33 parts 40% zinc stearate dispersion liquid (average particle size 0.9 μm) (trade name: High Micron F-930, manufactured by Chukyo Yushi Co., Ltd.) 13 parts Water 279 parts are mixed, The intermediate layer paint was used.

-Gloss layer outer coating layer paint Heavy calcium carbonate (Nitto Koka Kogyo, trademark: NS-1000) 70 parts Urethane acrylate emulsion (solid content 40%, Arakawa Kagaku, trademark: EM90) 25 parts Polysiloxane (33% solid content, manufactured by Toray Dow Corning Silicone, trademark: SM7025) 5 parts Water 40 parts were mixed to obtain a gloss layer outer coating layer paint.

-Gloss layer inner coating layer coating caprolactone-modified dipentaerythritol hexa (penta) acrylate (Nippon Kayaku, trademark: Kayarad DPCA-60) 70 parts epichlorohydrin-modified propylene glycol diacrylate 30 parts (Nagase Sangyo, trademark : Denacol DA-911) was mixed to obtain a coating for the inner coating layer of the gloss layer. Before providing the gloss layer, the back layer coating material was applied on the opposite surface by a bar coating method so that the coating amount after drying was 1.5 g / m ^2, and then smoothed by a super calendar. went.

-Back layer coating material Sodium polystyrene sulfonate (solid content 33%) (Sanyo Kasei, trademark: Chemistat SA-9) 30 parts SBR latex (solid content 50%) (Nippon Synthetic Rubber, trademark: 0528) 70 Part 10% aqueous solution of oxidized starch (Oji Cornstarch, trade name: Ace A) 150 parts 60% Kaolinite clay slurry 67 parts Water 83 parts were mixed to prepare a back layer paint.

On the other hand, a cured coating film of the coating material for the inner coating layer of the gloss layer was prepared by the following method to obtain a sample for a tensile test.
The above coating was applied to one surface of a PET film having a thickness of 75 μm using a wire bar so that the coating amount after curing was 20 g / m ² , and the surface of this coating layer was chromium plated. The coating layer was overlapped with the metal plate molding surface, and the coating layer was cured by irradiating an electron beam with an acceleration voltage of 175 KV and an absorbed dose of 4.0 Mrad under the PET film from the PET film side. Next, the cured coating film was sequentially peeled off from the metal molding surface and the PET film to obtain a sample for a tensile test.

Example 2 The same operation as in Example 1 was carried out, except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating Caprolactone modified dipentaerythritol hexa (penta) acrylate (Nippon Kayaku, trademark: Kayarad DPCA-60) 70 parts Epichlorohydrin modified 1,6-hexanediol diacrylate (Nippon Kayaku, trademark : Kayalad R-167) 30 parts was mixed to obtain a gloss layer inner coating composition.

Example 3 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed to the following. -Gloss layer inner coating layer coating bifunctional urethane acrylate oligomer (Daiichi Kogyo Seiyaku, trademark: New Frontier R-1204) 40 parts EO-modified trimethylolpropane triacrylate (Daiichi Kogyo Seiyaku, trademark: New Frontier TMP- 3) 30 parts 30 parts of acryloyl morpholine (trade name: ACMO, manufactured by Kojin Co., Ltd.) was mixed to obtain a coating for the inner layer of the gloss layer.

Example 4 The same operation as in Example 1 was carried out, except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating dipentaerythritol penta and hexaacrylate (Nippon Kayaku, trademark: Kayarad DPHA) 60 parts epichlorohydrin-modified 1,6-hexanediol diacrylate (Nippon Kayaku, trademark: Kayarad R-167 ) 30 parts 2-hydroxyethylmethacrylate 10 parts (Kyoeisha fat and oil, trademark: light ester HO) 10 parts of light calcium carbonate (manufactured by Shiraishi Kogyo, trademark: Brilliant-15) was mixed to give a gloss layer inner coating layer paint. .

Example 5 The same operation as in Example 1 was carried out, except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating dipentaerythritol hexa (penta) acrylate (Nippon Kayaku, trademark: Kayarad DPHA) 60 parts epichlorohydrin-modified 1,6-hexanediol diacrylate (Nippon Kayaku, trademark: Kayarad R- 167) 30 parts 2-hydroxypropyl methacrylate 10 parts (Made by Kyoeisha Oil and Fat, trademark: Light Ester HOP) 10 parts light calcium carbonate (manufactured by Shiraishi Kogyo, trademark: Brilliant-15) are mixed to form a gloss layer inner coating layer paint. did.

Comparative Example 1 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating Bifunctional urethane acrylate oligomer (manufactured by Arakawa Chemical Co., Ltd., trademark: Beamset 505B) 55 parts Hexaethylene glycol diacrylate () 45 parts were mixed to obtain a gloss layer inner coating layer coating. The Young's modulus of this cured coating film at 20 ° C. was 7.6 Kg / mm ² .

Comparative Example 2 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating bifunctional hydrogenated polybutadiene acrylate oligomer (Nippon Soda, trademark: NISSO PB TEAI-1000) 40 parts 1,9-nonanediol diacrylate (Daiichi Kogyo Seiyaku, trademark: L-C9A ) 60 parts were mixed to obtain a coating for the glossy layer inner coating layer. The Young's modulus of this cured coating film at 20 ° C. was 11.9 Kg / mm ² .

Comparative Example 3 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed to the following. -Gloss layer inner coating layer paint Glycerol type epoxy acrylate (Arakawa Chemical Co., Ltd., trademark: KU-310) 50 parts Dimethylol tricyclodecane diacrylate (Kyoeisha Oil & Fat, trademark: DCP-A) 50 parts The inner layer coating was used as the coating material. The Young's modulus of this cured coating film at 20 ° C. was 33.7 Kg / mm ² .

1 obtained in Examples 1 to 5 and Comparative Examples 1 to 3
A 10 mm width thermal recording medium was conditioned under an environmental condition of 20 ° C. and 65% RH for 2 hours, and then a commercially available thermal printer (Sony-
Image quality when recording with a trademark made by UP-860)
Printing defects and running defects were evaluated by the following methods. The Young's modulus when a tensile test was performed on a 20 mm wide sample obtained in the same manner was determined by the method described below.

(1) Image quality With respect to each of the 5 recorded materials, the sharpness, contrast, density unevenness of the image, etc. were visually judged and evaluated in 5 levels (◯: good, ◯ to Δ: slightly good, Δ). : Normal, △ to ×: somewhat defective, ×: defective). (2) Printing faults For each printed matter, 5 prints were visually checked to determine print faults due to the running trace of the thermal recording head and scraps, and evaluated in 5 levels (○: good, ○ to △: somewhat good). , △: Normal,
Δ to ×: somewhat defective, ×: defective). (3) Running defect Regarding the printed matter, the running length and the horizontal streak-like recording unevenness were visually judged on each of the five printed sheets, and evaluated in five stages (◯: good,
○ to △: Slightly good, △: Normal, △ to ×: Slightly bad, ×:
Bad).

(6) Young's modulus A tensile tester (made by Toyo Seiki, trademark: STROGR)
Set the gripping length to 10 mm in APH) and pulling speed 5
A tensile test was performed at mm / min to determine the Young's modulus from the initial gradient of the stress-strain curve of the coating film. The results are as shown in Table 1. In Examples 1 to 5, the image quality was good even in a high humidity environment condition, and the excellent print characteristics were shown. However, in any case, it was inferior to Examples 1 to 5.

[0052]

[Table 1]

[0053]

As is clear from Table 1, the thermosensitive recording medium of the present invention has excellent printing characteristics in addition to obtaining a recorded image having good image quality and high gloss and image clarity. , Is extremely useful in practice.

[Effect] In addition to good image quality, high gloss and image clarity, it also has excellent print characteristics.

[Procedure amendment]

[Submission date] July 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Further, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for curing the resin can be used. For example, glyoxal, dialdehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins,
Melamine resins, diglycidyl compounds such as glyceryl glycidyl ether, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, and ammonium persulfate and ferric chloride, and inorganic compounds such as magnesium chloride, sodium tetraborate and potassium tetraborate. Alternatively, boric acid, boric acid triester, or a boron-based polymer can be used in the range of 1 to 10% with respect to the solid content of the thermosensitive coloring layer.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

Example 4 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating dipentaerythritol penta and hexaacrylate (Nippon Kayaku, trademark: Kayarad DPHA) 60 parts epichlorohydrin-modified 1,6-hexanediol diacrylate (Nippon Kayaku, trademark: Kayarad R-167 ) 30 parts 2-hydroxyethyl methacrylate (manufactured by Kyoeisha Fat and Oil Co., Ltd., trademark: light ester HO) 10 parts Light calcium carbonate (manufactured by Shiraishi Kogyo, trademark: Brilliant-15) 10 parts were mixed to give a gloss layer inner coating layer paint. .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

Comparative Example 1 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed as follows. -Gloss layer inner coating layer coating Bifunctional urethane acrylate oligomer (Arakawa Chemical Co., Ltd., trademark: Beamset 505B) 55 parts Tetraethylene glycol diacrylate (Toagosei Chemical Co., Ltd., trademark: Aronix M-240) 45 parts The inner layer coating was used as the coating material. The Young's modulus of this cured coating film at 20 ° C. was 7.6 Kg / mm ² .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

Comparative Example 3 The same operation as in Example 1 was carried out except that the coating material for the inner coating layer of the gloss layer was changed to the following. -Gloss layer inner coating layer paint Bisphenol A epoxy acrylate (trade name: KU-300, manufactured by Arakawa Chemical) 50 parts Dimethylol tricyclodecane diacrylate (trade name: DCP-A, manufactured by Kyoeisha Oil & Fat Co., Ltd.) 50 parts The inner layer coating was used as the coating material. The Young's modulus of this cured coating film at 20 ° C. was 33.7 Kg / mm ² .

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

(4) Young's modulus A tensile tester (made by Toyo Seiki, trademark: STROGR)
Set the gripping length to 10 mm in APH) and pulling speed 5
A tensile test was performed at mm / min to determine the Young's modulus from the initial gradient of the stress-strain curve of the coating film. The results are as shown in Table 1. In Examples 1 to 5, the image quality was good even in a high humidity environment condition, and the excellent print characteristics were shown. However, in any case, it was inferior to Examples 1 to 5.

Claims (1)

[Claims] 1. A thermosensitive coloring layer is provided on at least one surface of a base material, and an intermediate layer is optionally provided on the thermosensitive coloring layer, and then the thermosensitive coloring layer or a gloss layer formed on the intermediate layer is formed. An outer coating layer containing a white pigment and an unsaturated organic compound curable by electron beam irradiation, and an inner coating layer mainly composed of an unsaturated organic compound curable by electron beam irradiation,
In addition, in the heat-sensitive recording material obtained by peeling the outer coating layer from the molding surface having high smoothness, the Young's modulus of the coating film of the inner coating layer is 50 Kg / mm ² or more at a temperature of 20 ° C. A heat-sensitive recording material characterized by the following.