JP2000085248A - Heat-sensitive recording material and heat-sensitive recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a heat-sensitive recording material suitable for preventing the wear of a thermal head at the time of printing by using the high output recording energy and provide a method therefor. SOLUTION: A heat-sensitive recording material is provided with a heat- sensitive recording layer and a protective layer on a substrate, and the protective layer is formed by applying a coating liquid as a polymer component containing latex or emulsion, and the moisture absorption rate of a solid content in the latex or emulsion at 24 deg.C and 40% RH is 2% or less. In the heat-sensitive recording method, recording is carried out by using the heat-sensitive recording material with 80 mJ/mm2 recording energy. Particularly the material is suitable as a medical heat-sensitive recording material for recording with 100 J/mm2 recording energy or more.

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, and more particularly, to a heat-sensitive recording material suitable for preventing wear of a thermal head used in heat-sensitive recording of a heat-sensitive recording material for recording with high output recording energy. The present invention relates to a thermal recording method using the thermal recording material.

[0002]

2. Description of the Related Art An image signal for modulating electric energy converted into thermal energy by a thermal head is obtained from, for example, an electronic scanning device or an intermediate storage device. The image signal flows through the thermal head electrode through a resistor layer covered by a continuous electrode disposed on the opposite side of the electrode. Then, during recording, the thermal head comes into direct contact with the protective layer constituting the surface of the thermosensitive recording material.

[0003] Since the thermal head is in direct contact with the protective layer constituting the surface of the thermal recording material, dirt and abrasion may occur, and when printing with high output recording energy,
For example, when printing is performed with a recording energy of 80 J / mm ² or more, particularly 100 J / mm ² or more, there is a problem that the thermal head is apt to be worn, and the life of the thermal head is shortened due to disconnection of the resistor.

[0004]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a heat-sensitive recording material capable of preventing a thermal head from being worn even when recording with high output recording energy. A second object of the present invention is to provide a thermosensitive recording method using the above thermosensitive recording material.

[0005]

SUMMARY OF THE INVENTION The first object described above is intended to provide:
A heat-sensitive recording material having a heat-sensitive recording layer and a protective layer on a support, wherein the protective layer is formed by applying a coating solution containing latex or emulsion as a polymer component. Solids,
This is achieved by a heat-sensitive recording material characterized in that the moisture absorption at 24 ° C. and 40% RH is 2% or less. The above-mentioned second object is to use the above-mentioned heat-sensitive recording material to obtain 80 mJ /
This is achieved by a thermal recording method in which recording is performed with a recording energy of ² mm or more.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described. The heat-sensitive recording material of the present invention has a heat-sensitive recording layer on a support, and has a protective layer on the heat-sensitive recording layer.
Latex or emulsion is used for this protective layer. As the latex, for example, styrene
Butadiene polymer latex (SBR latex, S
B latex, high styrene latex), acrylonitrile / butadiene copolymer latex, methyl methacrylate / butadiene copolymer latex, polyurethane latex, polyacrylate latex, acrylic emulsion, vinyl acetate polymer latex, polyvinylidene chloride latex, vinegar And bi-ethylene copolymer latex. As the emulsion,
An acrylic / styrene copolymer resin emulsion may be used.

[0007] These exemplified latexes or emulsions are of various grades depending on the emulsifier, functional group, other components, etc. Among these grades, there are 24 ° C. 40% R
It is necessary that the moisture absorption at H is 2% or less.

[0008] Here, that the moisture absorption at 2% or less at 24 ° C and 40% RH means that each latex or emulsion is applied to a support and then dried at 50 ° C for 20 minutes to form a film. . Next, the film was peeled from the support, and a sample of a predetermined size (10 cm × 10 c
m), and the weight (A) of the sample at this time was measured. Then, the sample was dried under the conditions of 24 ° C. and 40% RH.
The weight (B) at 4 hours is measured, and the moisture absorption is determined based on the following equation.

[0009]

(Equation 1) In the moisture absorption determined as described above, it is 2
% Is particularly effective in preventing abrasion of the thermal head during thermal recording.

For the protective layer in the present invention, the various latexes or emulsions described above may be used alone, or two or more different latexes or emulsions may be used in combination. The latex or emulsion may be used in combination with a water-soluble resin or the like in an amount that does not impair the effects of the present invention. Also in these cases, it is desirable that the liquid containing the components used in combination is applied and dried to form a film, and the film has a moisture absorption of 2% or less.

The protective layer according to the present invention may contain an organic or inorganic fine powder, a surfactant, a heat-fusible substance and the like. As fine powder, for example, calcium carbonate,
Silica, zinc oxide, titanium oxide, aluminum hydroxide,
Inorganic fine powders such as zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene However, inorganic pigments are particularly preferred. In the protective layer, latex or emulsion contains 10% solids.
It is desirable that the content be in the range of 95 to 95% by weight, preferably 20 to 90% by weight. Further, the thickness of the protective layer is 0.1 to 20 μm.
And more preferably 0.5 to 10 μm.
For the formation of the protective layer, any of the commonly known coating methods can be employed, but bar coating is particularly desirable.

The heat-sensitive recording layer in the present invention includes both a single-color heat-sensitive recording layer and a full-color heat-sensitive recording layer.
In the case of a heat-sensitive recording layer for a single color, it is preferable that the heat-sensitive coloring component contains an electron-donating colorless dye and an electron-accepting compound. In the case of a full-color heat-sensitive recording layer, a heat-sensitive recording layer using an electron-donating colorless dye and an acidic substance (electron-accepting compound) as a heat-sensitive coloring component is formed by laminating a plurality of heat-sensitive recording layers composed of a diazonium salt compound and a coupler. Is desirable.

Representative examples of the electron-donating colorless dye include a triarylmethane compound, a diphenylmethane compound, a thiazine compound, a xanthene compound, a spiropyran compound, and particularly, a triarylmethane compound, a xanthene compound. Is useful because of high color density. Examples of some of these include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (ie, crystal violet lactone),
3,3-bis (p-dimethylamino) phthalide, 3-
(P-dimethylaminophenyl) -3- (1,3-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindole-
3-yl) phthalide, 3- (o-methyl-p-dimethylaminophenyl) -3- (2-methylindole-3-
Yl) phthalide, 4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenylleuco-auramine, N-2,4,5-trichlorophenylleuco-auramine, rhodamine-B-anilinolactam,
Rhodamine (p-nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-phenyl Fluoran, 3-diethylamino-7- (3,4-dichloro) anilinofluoran,
3-diethylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-hyperidino-6-methyl-7-anilinofluoran, 3-ethyl-tolylamino-6 -Methyl-7-anilinofluoran, 3-ethyl-tolylamino-6-methyl-7-phenethylfluoran, 3-diethylamino-7- (4-nitroanilino) fluoran,
3-N-dibutylamino-6-methyl-7-fluoran, 2-anilino-3-methyl-6-N-ethyl-N-
Butyl-aminofluoran, benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, 3
-Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspirodinaphthopyran, 3
-Propyl-spiro-dibenzopyran and the like.

Examples of the electron-accepting compound include phenol derivatives, salicylic acid derivatives, and hydroxybenzoic acid esters. Particularly, bisphenols and hydroxybenzoates are preferred.

Examples of some of these are 2,4-dihydroxydiphenyl sulfone, 2,2-bis (p-hydroxyphenyl) propane (that is, bisphenol A), and 2,2-bis (p-hydroxyphenyl). ) Pentane, 2,2-bis (p-hydroxyphenyl) ethane,
2,2-bis (p-hydroxyphenyl) butane, 2,
2-bis (4'-hydroxy-3 ', 5'-dichlorophenyl) propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) propane, 1,1- (p- Hydroxyphenyl) pentane, 1,1- (p-hydroxyphenyl) -2-ethylhexane, 3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (tert-
Butyl) salicylic acid and its polyvalent metal salts, 3-α, α
-Dimethylbenzylsalicylic acid and its polyvalent metal salts,
butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol, p-cumylphenol and the like, with 2,4-dihydroxydiphenylsulfone being particularly preferred. It is.

In the heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound, it is desirable to add a sensitizer in order to start a color-forming reaction at a lower temperature. As the sensitizer, a low-melting organic compound having an aromatic group and a polar group in the molecule is preferable, and benzyl p-benzyloxybenzoate, α-naphthyl benzyl ether, β-naphthyl benzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p-chlorobenzyl) ether, 1,4-butanediol phenyl ether, 1,4-butanediol-p-methylphenyl Ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m-methylphenyl ether, 1-phenoxy-2- (p-tolyloxy) ethane, 1-phenoxy-2- (p- Ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane, p-benzyl Biphenyl and the like.

In the case of a thermosensitive recording layer comprising a diazonium salt compound and a coupler, an organic or inorganic basic substance can be further added for the purpose of accelerating the reaction between the two upon heating.

The diazonium salt compound and the general formula _{^{Ar-N 2 + X - (}} Ar wherein represents an aromatic moiety, N ₂ ⁺ diazonium salt, X ^- represents an acid anion) be a compound represented by These have various maximum absorption wavelengths depending on the position and type of the substituent in the Ar portion.

Specific examples of the diazonium salt compound used in the present invention include 4- (N- (2- (2,4-
Di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4-dioctylaminobenzenediazonium, 4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium , 4
-N-ethyl-N-hexadecylamino-2-ethoxybenzodiazonium, 3-chloro-4-dioctylamino-2-octyloxyobenzenediazonium, 2,
5-dibutoxy-4-morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-dibutoxy-4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium,
2,5-diethoxy-4- (N- (2- (2,4-di-
tert-amylphenoxy) butyryl) piperazino)
Benzenediazonium, 2,5-dibutoxy-4-tolylthiobenzenediazonium, 3- (2-octyloxyethoxy) -4-morpholinobenzenediazonium,
And so on.

As the acid anion, hexafluorophosphate salt, tetrafluoroborate salt, 1,5-naphthalene sulfonate salt and the like are useful.

Examples of the coupler which reacts with the above-mentioned diazonium salt at the time of heating to produce a color include resorcin, flurgurcine, 2,3-dihydroxynaphthalene-6-.
Sodium sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-
Dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3
-Naphthoic acid ethanolamide, 2-hydroxy-3-
Naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyloxypropylamide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetoanilide, 2-chloro-5-octylacetoacetanilide , 1-phenyl-3-methyl-5-pyrazolone, 1-
(2′-octylphenyl) -3-methyl-5-pyrazolone, 1- (2 ′, 4 ′, 6′-trichlorophenyl)
-3-benzamide-5-pyrazolone, 1- (2 ',
4 ', 6'-trichlorophenyl) -3-anilino-5
-Pyralone, 1-phenyl-3-phenylacetamido-5-pyrazolone and the like. These couplers can be used in combination of two or more to obtain a desired color hue.

The basic substance includes an inorganic or organic basic compound, as well as a compound which decomposes upon heating to release an alkaline substance. Representatives include organic ammonium salts, organic amines, amides, ureas and thioureas and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles , Morpholines, piperidines, amidines, formazines, pyridines and the like. Specific examples of these include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allylurea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenylimidazole, 2-phenylimidazole,
Phenyl-4-methylimidazole, 2-undecylimidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2-imidazoline, 2-phenyl-2-imidazoline, , 2,
3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetate, N, N′-dibenzylpiperazine, 4,4′-dithiomorpholine, morpholinium trichloroacetic acid Salts, 2-aminobenzothiazole, 2-benzoylhydrazinobenzothiazole and the like. These can be used in combination of two or more.

An ultraviolet absorber, an antioxidant, a metal soap, and waxes can be added to the heat-sensitive recording layer as needed. Examples of the ultraviolet absorber include ultraviolet absorbers such as benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, salicylic acid ultraviolet absorber, cyanoacrylate ultraviolet absorber, and oxalic acid anilide ultraviolet absorber. Any known ultraviolet absorber can be used, and examples of the antioxidant include a hindered amine antioxidant, a hindered phenol antioxidant, an aniline antioxidant, and a quinoline antioxidant. Particularly, hindered amine antioxidants such as 1,1,3-tris- (2-methyl-4-hydroxy-5-tbutylphenyl) butane are preferable. Examples of the metal soap include higher aliphatic polyvalent metal salts (for example, zinc stearate, aluminum stearate, calcium stearate, oleate, and the like.
Examples of the wax include paraffin wax, carnauba wax, microcrystalline wax, polyethylene bis-stearamide, higher fatty acid ester and the like.

The layer structure of the multicolor heat-sensitive recording material is not particularly limited, but, as an example, two different diazonium salt compounds having different photosensitive wavelengths and different diazonium salt compounds due to a hot reaction are used. A multicolor heat-sensitive recording material in which two layers of a heat-sensitive recording material in which a coupler that develops a hue is combined and a heat-sensitive recording material in which a combination of an electron-donating colorless dye and an electron-accepting compound are stacked is used. Specifically, a first thermosensitive recording layer (layer A) containing a colorless electron-donating dye and an electron-accepting compound on a support, a diazonium salt compound having a maximum absorption wavelength of 360 nm ± 30 nm, and a diazonium salt compound Heat-sensitive recording layer (B layer) containing a coupler which reacts with heat to form a color, a diazonium salt compound having a maximum absorption wavelength of 400 nm ± 30 nm, and a color reacts with the diazonium salt compound when heated. The third heat-sensitive recording layer (C layer) containing a coupler. In this example, a full-color image can be recorded by selecting the color hues of the respective heat-sensitive recording layers so as to be three primary colors, yellow, magenta, and cyan in the subtractive color mixing. Although any coating method can be adopted for the formation of the heat-sensitive recording layer, US Pat. No. 2,761,79
No. 1, No. 3,508,947, No. 2,941,8
No. 98 and No. 3,526,528, and the method described in Yuji Harazaki, “Coating Engineering”, p. 253 (published by Asakura Shoten in 1973) or the like can be applied simultaneously.

As the support in the present invention, a conventionally known support can be used. Specifically, high-quality paper, neutral paper, acidic paper, recycled paper, coated paper, polyolefin resin laminated paper, synthetic paper, polyester film, cellulose derivative film such as cellulose triacetate film, polystyrene film, polypropylene film and polyethylene film And the like. Particularly in the case of X-ray film or the like of the medical Ryoyo, are preferred polyethylene terephthalate.

The heat-sensitive recording material of the present invention is 80 mJ / mm.
It is preferably used as a heat-sensitive recording material for printing with a recording energy of ² or more.
It is suitable for medical X-ray films, full-color heat-sensitive recording materials, and the like that print with ^two or more high-output recording energies.

That is, the heat-sensitive recording material of the present invention is suitable for use in a reflection type print having a milky white light reflection background and a transparent positive when performing direct thermal recording with a thermal head or the like. In the field of hard copy, a white opaque substrate or a white light reflecting pigment is contained between the substrate and the heat-sensitive recording layer. The transparent positive, for example, the black-white transparent positive is used in the field of medical diagnosis in inspection technology operated with a light box.

[0028]

EXAMPLES Example 1 Preparation of Capsule Solution As a color former, 16 g of 2-anilino-3-methyl-6-N-ethyl-N-butyl-aminofluoran and Takenate D-110N (capsules of Takeda Pharmaceutical Co., Ltd.) 10 g of a wall material (trade name) was added to and dissolved in a mixed solvent of 20 g of ethyl acetate and 5 g of methylene chloride. 400 g of an 8% by weight aqueous solution of polyvinyl alcohol and water 1
After mixing 5 g and 0.5 g of a 2% by weight aqueous solution of dioctyl sulfosuccinate sodium salt (surfactant) with 0.5 g, the mixture was emulsified at 1000 rpm for 5 minutes using an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.). went. After further adding 70 g of water to the obtained emulsion,
The encapsulation reaction was carried out at 40 ° C. for 3 hours to obtain an average particle size of 0.7.
A μm capsule solution was prepared. In addition, the value of the 50% volume average particle diameter measured using a laser diffraction particle size distribution analyzer manufactured by Horiba, Ltd. was used for all the average particle diameters.

Preparation of Developer Emulsion Dispersion 4 g of a developer represented by the following structural formula (1)

[0030]

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2 g of a developer represented by the following structural formula (2)

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And 15 g of a developer represented by the following structural formula (3)

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4 g of 1-phenyl-1-xylylethane
And ethyl acetate in a mixed solvent of 15 g to dissolve. The obtained solution was treated with an 8% by weight aqueous solution of polyvinyl alcohol 4
0 g, 15 g of water and 0.5 g of sodium dodecylbenzenesulfonate were mixed in an aqueous phase, and then mixed with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.).
Emulsification was carried out at 00 rpm so as to have an average particle size of 0.5 μm to obtain a developer emulsion dispersion.

Preparation of Protective Layer Solution 50% by weight of polyvinylidene chloride latex (L536B, manufactured by Asahi Kasei Corporation; moisture absorption: 0.64%) 4g Water 46g 2% by weight Dioctyl sodium sulfosuccinate sodium salt solution 0.3g Water 100g and kaolin 35g Was mixed with a ball mill, and 3 g of a kaolin dispersion obtained by dispersion with a ball mill and 0.5 g of a 30% by weight zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd., Z-7-30) were mixed to prepare a protective layer solution. .

A solution obtained by stirring and mixing 5.0 g of the capsule liquid, 10.0 g of the developer emulsion dispersion and 5 g of water was mixed with polyethylene terephthalate (P) having a thickness of 175 μm.
ET) A thermosensitive recording layer was formed by coating and drying on the surface of the film to a solid content of 15 g / m ² . Next, the thickness of the protective layer liquid after drying is 2
The transparent thermosensitive recording material according to the present invention was prepared by coating and drying to a thickness of μm.

The heat-sensitive recording material having a width of 257 mm obtained as described above was used as a thermal head KGT-260-12MP8.
-FF (trade name, manufactured by Kyocera Corporation) and platen roll (iron core diameter 28 mm, rubber part diameter 36 mm, rubber hardness 7)
0 °, length 257 mm, roll pressure 7 kg) so that the heat-sensitive recording layer of the heat-sensitive recording material is on the side of the thermal head, and the recording energy is reduced in a room at a temperature of 24 ° C. and a relative humidity of 40% RH. 100mJ / mm ² , running speed 5.5mm
A recording run test was performed at / s. As a result, no unrecorded portion, which seems to be caused by the disconnection of the thermal head resistor, did not occur even when the distance exceeded 10 km.

Example 2 Preparation of Protective Layer Liquid 38% by weight of acrylonitrile / butadiene latex (Nipol 1577 manufactured by Zeon Corporation: 1.9% moisture absorption) 5.3g Water 44.7g 2% by weight Dioctyl sodium sulfosuccinate aqueous solution of sodium salt 0.3 g 100 g of water and 35 g of kaolin are mixed and then dispersed by a ball mill. 3 g of a kaolin dispersion obtained and 30 g of 30% by weight zinc stearate dispersion (Z-7-30, manufactured by Chukyo Yushi Co., Ltd.) 0.5 g are mixed. And a protective layer solution was prepared.

The same heat-sensitive layer solution as in Example 1 was applied and dried, and then the above-mentioned protective layer solution was applied in the same manner as in Example 1 to prepare a heat-sensitive recording material. A recording running test was performed in the same manner as in the above example. As a result, an unrecorded portion, which is considered to be caused by the disconnection of the thermal head resistor, was generated at a point when the distance exceeded 10 km.

Comparative Example 1 Preparation of Protective Layer Solution 50% by weight chloroprene latex (LT-50 manufactured by Denki Kagaku Kogyo Co., Ltd .: 2.8% moisture absorption) 4g Water 46g 2% by weight Dioctyl sulfosuccinate sodium salt aqueous solution 0.3g Ball mill after mixing 100g of water and 35g of kaolin 3g 30% by weight of zinc stearate dispersion (Z-7-30, manufactured by Chukyo Yushi Co., Ltd.) obtained by dispersing in 0.5 g was mixed to prepare a protective layer solution.

The same heat-sensitive layer solution as in the example was applied and dried, and then the protective layer solution was applied in the same manner as in the example to prepare a heat-sensitive recording material. A recording running test was performed in the same manner as in the above example. As a result, an unrecorded portion was considered attributable to disconnection of the thermal head resistor when the traveling distance exceeded 5 km, which is a shorter traveling distance than in the above-described embodiment.

Comparative Example 2 Preparation of Protective Layer Liquid 10% by weight carboxyl-modified polyvinyl alcohol aqueous solution (manufactured by Kuraray Co., Ltd., KM618: 4.7% moisture absorption) 20 g Water 30 g 2% by weight Dioctyl sulfosuccinate Na salt aqueous solution 0.3 g 100 g of 3% by weight polyvinyl alcohol (PVA205 manufactured by Kuraray Co., Ltd.) 100 g of kaolin mixed with 35 g of kaolin and dispersed by a ball mill 3 g of 30% by weight dispersion of zinc stearate (Z-7 manufactured by Chukyo Yushi Co., Ltd.) -30) 0.5 g was mixed to prepare a protective layer solution.

The same heat-sensitive layer liquid as in the example was applied and dried, and then the protective layer liquid was applied in the same manner as in the example to prepare a heat-sensitive recording material. A recording running test was performed in the same manner as in the above example. As a result, an unrecorded portion was considered attributable to disconnection of the thermal head resistor when the traveling distance exceeded 3 km, which is a shorter running distance than in the above-described embodiment.

[0043]

As described above, according to the heat-sensitive recording material of the present invention, even in the heat-sensitive recording material for printing with high-output recording energy, the wear of the thermal head is small. The life of the thermal head can be extended. In addition, according to the thermal recording method of the present invention, when printing is performed at a high output of 80 mJ / mm ² or more, the wear of the thermal head is small, so that there is no disconnection of the resistor and the life of the thermal head can be extended. .

Claims (2)

[Claims] 1. A thermosensitive recording material having a thermosensitive recording layer and a protective layer on a support, wherein the protective layer is formed by applying a coating solution containing latex or emulsion as a polymer component. 2% moisture absorption at 24 ° C and 40% RH in solids in latex or emulsion
A heat-sensitive recording material comprising: 2. A thermal recording method using the thermal recording material according to claim 1 for recording with a recording energy of 80 mJ / mm ² or more.