JPH0664326A - Thermal recording body - Google Patents

Abstract

PURPOSE:To obtain a high-gloss thermal recording body having no possibility of an occurrence of sticking at the time of recording, a high recording density, and a good contrast. CONSTITUTION:In a thermal recording body provided with a thermal color- forming layer, an intermediate layer, and a gloss layer on a substrate, a pigment having an average particle diameter 1-3 times larger than the total coating thickness of the intermediate layer and the gloss layer is compounded in the intermediate layer. In this manner, in the thermal recording body, a high gloss is kept, sticking and scratch marks never occur, and the pigment particle is not separated by a slitter or the like.

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, and more specifically to a thermal recording material suitable for use in an image thermal printer which outputs a CRT image for medical measurement as a hard copy. It is a thing.

[0002]

2. Description of the Related Art A heat-sensitive recording material is generally composed of paper, synthetic paper, plastic film or the like on at least one surface thereof, and a colorless or light-coloring substance such as an electron-donating leuco dye and an electron-accepting phenol. A thermosensitive coloring layer containing an organic acidic developer such as a polymerizable compound and an adhesive as main components, and the coloring dye is reacted with the developer by heat energy to record a color. Images can be obtained.

Such a thermal recording medium has the advantages that the recording apparatus is compact and inexpensive, and that maintenance is easy, and is only used as a recording medium for facsimiles, automatic ticket vending machines, and scientific measuring machines. Not POS label, C
It is widely used as an output medium for various printers and plotters for AD and CRT medical images. Among them, an image printer for CRT medical measurement that requires uniformity of recorded images and high resolution, and C that requires dimensional stability and fine line recording.
For the AD plotter, a synthetic paper having a multi-layer structure or a biaxially stretched thermoplastic resin film containing an inorganic pigment as necessary is used.

In particular, for image printer paper for CRT medical measurement, recording paper having high whiteness and high gloss is desired, but conventional recording paper has low gloss and insufficient contrast. . The glossiness of the thermosensitive recording medium is determined by, for example, JIS in order to make the contrast satisfactory.
The glossiness of the printed part measured according to P 8142 is 60%
The above is necessary. Therefore, it is necessary to provide an intermediate layer and a gloss layer on the heat-sensitive coloring layer, but since only a small amount of pigment of 10% or less can be blended in the gloss layer, the smoothness becomes high, and sticks and scratches occur. There was a problem to do.

In order to prevent sticking and scratches, it is necessary to reduce the smoothness of the gloss layer. As a method of reducing the smoothness with a blending amount of 10% or less, the average particle size is larger than the thickness of the gloss layer. It may be possible to mix the pigment into the glossy layer, but in this case, there is a problem that the pigment falls off by a super calender or a slitter, which not only causes a problem in operation but also loses the effect of improving stick and scratches.

[0006]

SUMMARY OF THE INVENTION In order to improve the glossiness of a heat-sensitive recording material and to improve sticking and scratches, the present invention provides
It is an object of the present invention to provide a thermal recording material in which a small amount of a pigment having a particle size larger than the thickness of the glossy layer is mixed in the glossy layer, and the pigment does not fall off in a super calendar or a slitter.

[0007]

[Means for Solving the Problems] The inventors of the present invention blend a pigment having an average particle diameter larger than the thickness of the gloss layer into the gloss layer so as not only to enhance the glossiness but also to prevent sticks and scratches from occurring. The present invention has been completed as a result of intensive studies on the method for preventing the pigment from falling off with a super calender or a slitter in the heat-sensitive recording material.

That is, according to the present invention, a thermosensitive coloring layer containing a colorless or light-colored electron-donating leuco dye, an organic acidic substance that develops the leuco dye by heating and an adhesive as main components is provided on at least one surface of the support. After providing an intermediate layer containing a water-soluble resin and / or a water-dispersible resin, a pigment and a cross-linking agent as a main component on the thermosensitive coloring layer, the water-soluble resin and / or the water-dispersible property on the intermediate layer. In a heat-sensitive recording material provided with a glossy layer containing a resin and a lubricant as a main component, a pigment having an average particle size larger than the total thickness of the intermediate layer and the glossy layer and less than or equal to 3 times is added to the intermediate layer. This prevents the pigment from falling off on the super calendar and slitter.

If the average particle size of the pigment is larger than the thickness of the intermediate layer, it is easy to fall off when a lateral force is applied to the surface of the coating film, but by applying a gloss layer on it, the adhesive strength is increased. And the dropout of the pigment is eliminated even when subjected to a super calendering treatment after coating the glossy layer or a strong force such as slitter processing. Moreover, since the smoothness of the glossy layer is lowered, the problems of sticking and scratching are improved.
It is difficult to accurately measure the film thickness of the intermediate layer and the gloss layer, but for convenience, the specific gravity of the coating film is set to 1.0, and the coating amount (g / m ² ) is the same as the film thickness (μm). It may be calculated as being equal to.

The support 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 stacking layers and stretching in the transverse direction, and thermoplastic resin such as polyolefin-based resin and polyester-based resin, or a mixture obtained by extruding biaxially a mixture of thermoplastic resins from a die, and a white inorganic material for the thermoplastic resin. In addition to those obtained by extruding a pigment obtained by heat-kneading from a die and biaxially stretching it, those produced from pulp fibers such as high-quality paper, 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, as main components, a colorless or light-colored electron-donating leuco dye, an organic acidic substance that develops the color of the leuco dye by heating, and an adhesive, and if necessary, a white pigment, It may contain a heat-fusible substance, an auxiliary additive component such as a dispersant, a defoaming agent, a fluorescent dye and the like.

The thermosensitive coloring layer of the present invention is applied to at least one surface of the above-mentioned support by a coating method such as an air knife method, a Meyer bar method, a blade method, a reverse roll method or a slit die method which has been conventionally used by those skilled in the art. formed by coating amount after drying 2~12g / m ^2, desirably it applied so as to 4~10g / m ^2. Further, by smoothing the surface of the thermosensitive coloring layer with a super calender, a gloss calender, a machine calender, etc., the coatability of the intermediate layer can be improved and an intermediate layer having a uniform thickness can be formed.

The color-forming dye used in the present invention is a colorless or light-colored electron-donating leuco dye capable of reacting with a color developer under heating to form a color. For example, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro (phthalide-3,9'-xanthene) -2'-ylamido] phenyl} propane, 3
-Diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino)
-6-Methyl-7-anilinofluorane, 3-diethylamino-7-chloroanilinofluorane, 3- [N-ethyl-N- (p-methylphenyl) amino] -6-methyl-7-anilino Fluoran, 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 -(N, N-dibutyl) amino-
It is composed of at least one member of a fluoran dye such as 6-methyl-7-anilinofluorane.

The color developer used in the present invention comprises an electron-accepting organic acidic substance capable of reacting with a color-forming dye under heating to develop 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. Since the color developer usually has the highest color density,
It is mixed and used in a ratio of 1 to 5 parts by weight, preferably 1.5 to 3 parts by weight with respect to 1 part by weight of the color forming dye.

The color developer is, for example, 4,4'-isopropylidene diphenol (bisphenol A), 4,4'-.
Isopropylidene bis (2-chlorophenol), 4,
4'-isopropylidene bis (2-methylphenol), 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'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenyl sulfone, 3,3'-dihydroxydiphenyl sulfone, 3,3'-diamino-4,4'-dihydroxy-diphenyl sulfone, 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'-isopropyloxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 2,4-dihydroxydiphenyl sulfone,
It is composed of at least one member selected from 2,4-dihydroxy-4′-methyldiphenyl sulfone, 3,4-dihydroxyphenyl-p-trisulfone and the like.

In the present invention, the adhesive contained in the thermosensitive coloring layer may be either a water-soluble resin or a water-dispersible resin. For example, polyvinyl alcohol, starch, modified starch, gum arabic, gelatin, casein, chitosan,
Methyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid salt, polyacrylic amide, polyester resin, styrene-acrylic acid ester copolymer resin, styrene-maleic anhydride copolymer resin, methyl vinyl ether-maleic anhydride copolymer resin , Water-soluble resins such as isopropylene-maleic anhydride copolymer resin, and vinyl acetate emulsion, acrylic ester copolymer emulsion, methacrylic ester copolymer emulsion, vinyl acetate- (meth) acrylic ester copolymer emulsion, polyurethane emulsion , Polyvinyl chloride emulsion, polyvinylidene chloride emulsion, SBR latex, MBR latex and other emulsions with a minimum film forming temperature of 20 ° C or less. The good water-dispersible resin alone or in combination may be used.

However, it is necessary that the mixed liquid does not develop color, aggregate, or have a high viscosity when mixed with the respective dispersion liquids of the color forming dye and the color developing agent,
Further, it is necessary that the formed heat-sensitive recording layer film be tough and have 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 polyaldehydes, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins,
Melamine resins, diglycidyl compounds such as glycerin diglycidyl ether, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, and ammonium persulfate, ferric chloride, magnesium chloride, sodium tetraborate, potassium tetraborate, etc. Inorganic compounds or boric acid, boric acid triesters, and boron-based polymers can be used in the range of 1% to 10% with respect to the solid content of the thermosensitive coloring layer.

Examples of white pigments usable in the heat-sensitive layer of the present invention include calcium carbonate, magnesium carbonate, magnesium oxide, 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 organic pigments such as urea resin, styrene-methacrylic acid copolymer, polystyrene resin, etc., having an average particle size of 5 μm.
The following fine particle pigments can be used. Furthermore, in order to improve the wetting of the heat-sensitive layer coating and eliminate cissing, a wetting improving agent such as acetylene glycol or dialkyl sulfosuccinate may be added.

Examples of the heat-fusible substance include stearic acid amide, stearic acid ethylenebisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide,
Fatty acid amides such as behenic acid amide, zinc stearate, calcium stearate, polyethylene wax,
Waxes such as carnauba wax, paraffin wax, ester wax, oxalic acid di-p-methylbenzyl ester, oxalic acid di-p-chlorobenzyl ester, 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'-butylidenebis (6-t-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butyl) Phenyl) butane, 2,2′-methylenebis (4-ethyl-6-t-butylphenol),
2,4-di-t-butyl-3-methylphenol, 4,
Hindered phenols such as 4′-thiobis (3-methyl-6-t-butylphenol), 2- (2′-hydroxy-5′-methylphenyl) -benzotriazole,
And sensitizers such as 2-hydroxy-4-benzyloxybenzophenone, antioxidants, and ultraviolet absorbers.
In general, the heat-fusible 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.

The intermediate layer provided on the thermosensitive coloring layer of the present invention is
There are problems such as when the required glossiness cannot be obtained even if the gloss layer is directly applied on the thermosensitive coloring layer, or the thermosensitive coloring layer is colored or the colored portion is erased due to the influence of the chemicals of the gloss layer. In order to prevent an increase in smoothness after coating the gloss layer, a pigment having an average particle size larger than the total film thickness of the intermediate layer and the gloss layer and not more than 3 times is blended. To do.

The water-soluble and / or water-dispersible resin used for the intermediate layer has poor crystallinity, good film-forming property, strong binding force, and after drying, it may become a colorless and transparent continuous film. desirable. Such a resin can be appropriately selected and used from the resins used for the thermosensitive coloring layer. The resin content is preferably 40 to 90% with respect to the solid content of the intermediate layer. The crosslinking agent used in the intermediate layer can be appropriately selected from the crosslinking agents used in the thermosensitive color developing layer. The compounding amount of the crosslinking agent is preferably 1 to 20% with respect to the solid content of the intermediate layer.

The pigments used in the intermediate layer have good average stick size and dust, in addition to those of the present invention in which the average particle size is larger than the total film thickness of the intermediate layer and the gloss layer and not more than 3 times. Further, an extender pigment having a large oil absorption property and an average particle size smaller than the thickness of the intermediate layer can be used. The average particle size of the pigment of the present invention needs to be larger than the total film thickness of the intermediate layer and the gloss layer, but if it exceeds 3 times, the smoothness of the gloss layer is greatly reduced and the uniformity of the image is deteriorated. There is. Usually, the total film thickness of the intermediate layer and the gloss layer is 1 to 6 μm, so that the average particle diameter of the pigment of the present invention to be blended in the intermediate layer must be larger than 1 μm and 18 μm or less.

Such a pigment is an inorganic pigment or an organic pigment, which can be appropriately selected and used from the pigments used in the thermosensitive coloring layer. Calcium carbonate, magnesium carbonate, magnesium oxide, kaolin, clay, talc. ,
Among inorganic pigments such as calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated calcium carbonate and silica, only primary particles having a large particle size Alternatively, secondary particles having a large particle size can also be used. Further, organic pigments such as urea resin powder, styrene-methacrylic acid copolymer powder, polystyrene resin powder, benzoguanamine resin powder, and silicon resin powder, which are fine particle pigments having an average particle size of more than 1 μm and 18 μm or less can be used.

The extender pigment having a large oil absorbing property is used in the thermosensitive coloring layer, and fine particles having an average particle diameter of 1 μm or less can be used.

The intermediate layer has a coating amount after drying on the thermosensitive coloring layer of 0.5 to 5.5 g / m ² , preferably 1.0 to 5.0.
It can be obtained by coating g / m ² . The coating method can be appropriately selected and used from among the methods used for the thermosensitive coloring layer. If the coating amount of the intermediate layer is less than 0.5 g / m ² , the coating film is not formed uniformly, so that the coating material of the gloss layer coated on the coating layer penetrates and the gloss development property decreases. When the coating amount exceeds 5.5 g / m ² , the glossiness is improved, but the sensitivity is lowered and the recording density is lowered.

Among the pigments mixed in the intermediate layer, the mixing ratio of the pigments having an average particle diameter of more than 1 time and less than 3 times the film thickness of the intermediate layer and the gloss layer is 0.1 to 10 based on the solid content of the intermediate layer. % Is good. If it is less than 0.1%, it is difficult to control the smoothness, and if it exceeds 10%, there is a problem that the glossiness is lowered. The pigment of the intermediate layer including the extender pigment is preferably 0.1 to 50% with respect to the solid content of the intermediate layer, and if it exceeds 50%, there are drawbacks that the glossiness is deteriorated and the recording density is lowered.

The gloss layer provided on the intermediate layer contains a water-soluble resin and / or a water-dispersible resin and a lubricant as main components, and optionally a cross-linking agent to enhance gloss after recording. At the same time, the running performance of sticks, scraps and the like is improved. Water-soluble resin used for gloss layer and /
Alternatively, the water-dispersible resin is the one used in the thermosensitive coloring layer,
It is possible to select and use a resin having a good sliding property such as a silicone-acrylic copolymer resin or a silicone resin, which has a high gloss after recording. The resin content is preferably 50 to 90% with respect to the solid content of the gloss layer.

Lubricants used in the gloss layer include alkyl lauric acid esters such as lauryl phosphoric acid ester, oleyl phosphoric acid ester and stearyl phosphoric acid ester, and alkali metal salts thereof, lauryl sulfonic acid ester, oleyl sulfonic acid ester, stearyl sulfonic acid ester. Alkylsulphonic acid esters such as glyceryl monomyristate, glyceryl monomyristate, glyceryl monostearate, glyceryl monooleate, glyceryl distearate, glyceryl fatty acid esters such as glyceryl dioleate, diglyceryl monolaurate, diglyceryl dilaurate , Tetraglyceryl monolaurate,
There are polyglycerin fatty acid esters such as hexaglyceryl monolaurate and decaglyceryl monolaurate.

The amount of the lubricant used in the gloss layer is preferably 5 to 40% with respect to the solid content of the gloss layer, and if it is less than 5%, the sticking effect is not exerted. If it exceeds 40%, the strength of the gloss layer decreases. It's a problem. The crosslinking agent used in the gloss layer, if necessary, can be selected from those used in the heat-sensitive color developing layer. The compounding amount of the crosslinking agent is preferably 1 to 40% with respect to the solid content of the gloss layer.

If the coating amount of the gloss layer is less than 0.5 g / m ² , the coating film is not formed uniformly, so that the glossiness is not high and the stick is also deteriorated. Coating amount is 5.0g / m
^If it exceeds ² , the gloss and stick are improved, but the sensitivity and recording density are lowered. The coating method of the gloss layer can be selected and used from those used for coating the thermosensitive coloring layer.

After the gloss layer is applied, a back layer is applied if necessary from the viewpoint of curl prevention and antistatic property, and further smoothing treatment is carried out with a super calendar, gloss calendar, machine calendar or the like to obtain an image. The uniformity can be improved and the glossiness can be increased.

[0033]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. In each example, “part” means “part by weight”. Example 1 On one surface of synthetic paper YUPO FPG-80, the thermosensitive coloring layer coating material shown below was applied so that the coating amount after drying was 6.5 g / m ^2, and the intermediate layer coating material and The coating amount after drying the gloss layer coating is 1.0 g / m ² and 1.0 g / m ² , respectively.
Sequential coating was applied to give ² .

Preparation of coating material for thermosensitive coloring layer Liquid A (thermosensitive coloring dye dispersion liquid) 3- (N, N-dibutyl) amino-6-methyl-7-anilinofluorane 20 parts 10% polyvinyl alcohol aqueous solution 20 Part Water 10 parts Solution B (developing agent dispersion) 4-Hydroxy-4'-isopropyloxydiphenyl sulfone 50 parts 10% polyvinyl alcohol aqueous solution 50 parts Water 25 parts Disperse solutions A and B separately with Ultraviscomill. It was pulverized and adjusted so that the average particle diameter was 1 μm or less. A solution 38 parts, B solution 75 parts, 60% calcium carbonate slurry 50 parts, 10% polyvinyl alcohol (Gohsenol NM-11, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) aqueous solution 60
Part, SBR latex (PT-1004, solid content 43
%, Manufactured by Nippon Zeon Co., Ltd., 33 parts of 30% zinc stearate dispersion, and 60 parts of water were mixed to obtain a thermosensitive coloring layer coating material.

Intermediate layer paint 60% Kaolinite clay (average particle size 0.6 μm) dispersion 33 parts Carboxy modified polyvinyl alcohol (Gosenal T-330, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) aqueous solution (solid content 10%) 310 Part Acrylic emulsion (SC-1225, solid content 40%, manufactured by Nippon Shokubai Co., Ltd.) 88 parts Dimethylol urea solution (solid content 30%) 33 parts 30% benzoguanamine resin powder dispersion (Eposter M-30, average particle size 3 0.0 μm, manufactured by Nippon Shokubai Co., Ltd. 13 parts water 523 parts were mixed to obtain an intermediate layer paint.

-Gloss layer paint Polysiloxane graft acrylic emulsion (GF-256, manufactured by Nippon Shokubai Co., Ltd., solid content 20%) 375 parts Alkyl phosphate ester potassium salt (TRL-20, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) Solid content 50%) 40 parts Water 245 parts were mixed to obtain a gloss layer paint. Further, the back layer coating material was applied to the opposite surface so that the coating amount after drying was 1.5 g / m ² . Smoothing treatment was carried out with a super calendar to obtain a heat-sensitive recording material having a glossy layer having an Oken type smoothness (J.TAPPI No. 6) of 7,000 seconds.

Back layer paint Sodium polystyrene sulfonate (Chemistat SA-9, Sanyo Kasei Co., Ltd., solid content 33%) 30 parts SBR latex (0528, Nippon Synthetic Rubber Co., Ltd., solid content 50%) 70 Part 10% aqueous solution of oxidized starch (Ace A, manufactured by Oji Corn Starch Co., Ltd.) 150 parts 60% Kaolinite clay slurry (Hydrogross 90, manufactured by Huber) 67 parts Water 83 parts were mixed to prepare a back layer coating material.

Examples 2 to 4 Thermal recording media were obtained in the same manner as in Example 1 except that the intermediate layer shown below was used instead of the intermediate layer used in Example 1.

Example 2 ・ Intermediate layer paint 20% colloidal silica dispersion (Snowtex C, average particle size 0.01 μm, manufactured by Nissan Chemical Industries, Ltd.) 150 parts Carboxy-modified polyvinyl alcohol aqueous solution (Gosenal T-350, solid) Min. 10%, manufactured by Nippon Synthetic Chemical Co., Ltd. 190 parts Urethane-modified acrylic emulsion (Boncoat 3986, solid content 40%, manufactured by Dainippon Ink and Chemicals, Inc.) 100 parts Dimethylol urea solution (solid content 30%) 27 parts 30 % Magnesium oxide powder dispersion (HP-10, average particle size 5.0 μm, manufactured by Kamijima Chemical Industry Co., Ltd.) 10 parts Water 524 parts were mixed to form an intermediate layer paint.

Example 3 Intermediate layer paint 20% colloidal silica dispersion (Snowtex C, average particle size 0.01 μm, manufactured by Nissan Chemical Industries, Ltd.) 150 parts Acetoacetylated polyvinyl alcohol aqueous solution (Z-100, solid) Min 10%, manufactured by Nippon Gohsei Co., Ltd. 200 parts SBR latex (solid content 50%) 54 parts glyoxal solution (solid content 40%) 50 parts 30% silicone resin powder dispersion (Tospearl 145, average particle size 4. 5 μm, manufactured by Toshiba Silicone Co., Ltd. 10 parts water 536 parts were mixed to obtain an intermediate layer paint.

Example 4 ・ Interlayer paint 20% colloidal silica dispersion (Snowtex C, average particle size 0.01 μm, manufactured by Nissan Kagaku Co., Ltd.) 150 parts Polyvinyl alcohol (Gothenol NM-11, Nippon Synthetic Chemical Co., Ltd. )) Aqueous solution (solid content 10%) 120 parts Urethane emulsion (AP-30, solid content 20%, Dainippon Ink and Chemicals, Inc.) 200 parts Boron polymer (Hiboron DDGB-90, solid content 90%, Boron International 11 parts 50% marimo-like calcium carbonate dispersion liquid (Callite SA, average particle size 3.5 μm, manufactured by Shiraishi Calcium Co., Ltd.) 16 parts Water 503 parts were mixed to form an intermediate layer paint.

[0042] In Example 5 Example 1, the intermediate layer and gloss layer respectively 2.5 g / m ² or less of the coating as, except that 1.5 g / m ² coated in the same manner as in Example 1 heat-sensitive recording material It was created. -Intermediate layer paint 60% Kaolinite clay (average particle size 0.6 μm) dispersion 33 parts Polyvinyl alcohol aqueous solution (PVA-117, solid content 10%, manufactured by Kuraray Co., Ltd.) 300 parts Acrylic emulsion (Honlon S-480, Solid content 47%, manufactured by Mitsui Toatsu Chemicals, Inc. 95 parts Dimethylol urea solution (solid content 30%) 33 parts 20% Amorphous silica powder dispersion (Cyloid 74, average particle size 7 μm, Fuji Devison Chemical Co., Ltd.) (Manufactured) 10 parts Water 529 parts were mixed to form an intermediate layer paint.

-Gloss layer paint Acrylic / silicon modified resin emulsion (Siren ARJ-2A, solid content 44%, manufactured by Nippon Pure Chemical Co., Ltd.) 191 parts Nonionic surfactant (Ekcor 214, solid content 40% Matsumoto Yushi-Seiyaku ( Co., Ltd.) 40 parts Aziridine compound (crosslinking agent) 3 parts Water 766 parts was mixed to obtain a gloss layer paint.

Example 6 and Example 7 A thermosensitive recording medium was prepared in the same manner as in Example 5 except that the following coating material was applied as the intermediate layer coating material. Example 6-Intermediate layer paint 70% Calcium carbonate (average particle size 0.8 μm) dispersion 14 parts Polyvinyl alcohol (Gohsenol NL-05, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) aqueous solution (solid content 10%) 300 parts Silica composite Styrene-acrylic emulsion (LX-612, solid content 40%, Hoechst Synthetic Co., Ltd.) 95 parts Boron polymer (Hiboron DDGB-90, solid content 90%, Boron International Co., Ltd.) 33 parts Urea resin powder (Upearl) C-120, average particle diameter 10 μm, solid content 20%, Mitsui Toatsu Kagaku KK 10 parts water 529 parts were mixed to form an intermediate layer paint.

Example 7-Intermediate layer paint 60% Kaolinite clay (average particle size 0.6 μm) dispersion 33 parts Modified polyvinyl alcohol (Gosenal T-330, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) aqueous solution (solid content 10% ) 370 parts Acrylic emulsion (Aron NS-1200, solid content 40%, manufactured by Toagosei Chemical Industry Co., Ltd.) 75 parts Glyoxal solution (solid content 40%) 25 parts 30% magnesium oxide powder dispersion (HP-10, average) Particle size 5.0 μm, 10 parts water 487 parts manufactured by Kamijima Chemical Industry Co., Ltd. were mixed to obtain an intermediate layer paint.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the intermediate layer coating material containing no pigment having an average particle diameter larger than the coating thickness of the intermediate layer was used. -Intermediate layer paint 60% Kaolinite clay (average particle size 0.6 μm) dispersion 33 parts Carboxy-modified polyvinyl alcohol (Gosenal T-330, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) aqueous solution (solid content 10%) 350 parts Acrylic emulsion (SC-1225, solid content 40%, manufactured by Nippon Shokubai Co., Ltd.) 88 parts Dimethylol urea solution (solid content 30%) 33 parts Water 496 parts were mixed to form an intermediate layer paint.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 1 except that the gloss layer coating material containing a pigment having an average particle size larger than the coating thickness of the gloss layer was applied. -Gloss layer paint Polysiloxane graft acrylic emulsion (GF-256, manufactured by Nippon Shokubai Co., Ltd., solid content 20%) 380 parts Alkyl phosphate potassium salt (TRL-20, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. solid content 50%) 40 parts 30% benzoguanamine resin powder dispersion (Eposter M-30, average particle size 3.0 μm, manufactured by Nippon Shokubai Co., Ltd.) 13 parts Water 567 parts were mixed to obtain a gloss layer coating material.

Pigment dropping when the thermal recording materials obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were slitted, and gradation recording was performed with a commercially available thermal printer (UP-850, manufactured by Sony). Then, the reflection density of the highest density portion, the stick sound during recording, and the scratches on the surface were evaluated. The results are as shown in Table 1. In Examples 1 to 7, there was no dropout of the pigment in the slitter, no stick sound, high recording density, and high contrast recording was obtained. In Example 1, a stick sound was heard during recording, the recording length was short, and many scratches were generated. In Comparative Example 2, the pigment was dropped off by the slitter and the stick was insufficient.

[0049]

[Table 1]

Gloss: Measured according to JIS P 8142. Pigment dropout: Evaluation of slitter paper roll dirt ○: No dirt. X: There is dirt. Recording density: Measured with a Mcbeth RD-914 densitometer. Stick: The loudness of the sound being recorded was evaluated. ○: There is almost no sound. Δ: There is a small sound. Scratch: Visual evaluation of solid recording area ◯: No scratch. X: There are many scratches.

[0051]

INDUSTRIAL APPLICABILITY According to the present invention, when a thermal recording material is produced, no pigment is removed by a super calendar or a slitter, and when recording by a thermal printer, no stick or scratches occur, the image density is high, and the contrast is high. You can get a high record.

 ─────────────────────────────────────────────────── --Continued front page (72) Inventor Toru Murai 1-10-6 Shinonome, Koto-ku, Tokyo Oji Paper Co., Ltd. Product Research Laboratory

Claims (1)

[Claims] 1. A heat-sensitive coloring layer containing a colorless or light-colored electron-donating leuco dye, an organic acidic substance capable of coloring the leuco dye by heating, and an adhesive as main components on at least one side of the support. After providing an intermediate layer containing a water-soluble resin and / or a water-dispersible resin, a pigment and a cross-linking agent as a main component on the color forming layer, the water-soluble resin and / or the water-dispersible resin and a lubricant are further provided on the intermediate layer. In a thermal recording material having a glossy layer containing as a main component, a pigment having an average particle size larger than the total thickness of the intermediate layer and the glossy layer and not more than 3 times is blended in the intermediate layer. A thermosensitive recording medium.