JP3201878B2 - Thermal recording material and method for producing the same - Google Patents

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 which is excellent in chemical resistance of recorded images and background and can record high-quality images.

[0002]

2. Description of the Related Art In recent years, thermal recording methods have been used in various fields such as facsimile machines and printers, because they have high reliability and do not require maintenance despite the simple use of a recording apparatus. However, heat-sensitive recording materials have poor resistance to chemicals such as oils and plasticizers. Therefore, when a recorded image is stored in contact with a plastic film containing a plasticizer or the like for a long time, the density of the recorded image decreases. was there.

As a method for solving such a drawback, a method of providing a protective layer containing a specific amount of a fluorine-containing surfactant on a color-forming layer (JP-A-57-107884), or a method of forming a protective layer on a heat-sensitive recording layer is disclosed. A water-soluble resin layer containing a specific amount of an alkylsulfosuccinate (Japanese Patent Laid-Open Publication No.
No. 17479) is known. However, in any of the above methods, although the chemical resistance is improved, it is difficult to apply the protective layer uniformly (referred to as cissing) because the protective layer coating solution is repelled on the heat-sensitive recording layer at the time of application. Therefore, when an image is recorded by using such a heat-sensitive recording material, there is a disadvantage that the density unevenness based on the repelling occurs in the recorded image and the quality of the recorded image becomes poor. Further, when the coating liquid for the protective layer is applied by using a hopper type coating apparatus, the coating property is poor and an uncoated portion occurs, so that there is a disadvantage that sticking prevention is not sufficient.

[0004]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned drawbacks, and as a result, provided a polymer binder layer containing a specific amount of an alkylbenzene sulfonate as a protective layer. In this case, it was found that a good heat-sensitive recording material was obtained, and the present invention was reached.

Accordingly, a first object of the present invention is to provide not only excellent chemical resistance but also excellent sticking resistance.
An object of the present invention is to provide a heat-sensitive recording material having excellent image quality.
A second object of the present invention is to provide a method for producing a heat-sensitive recording material which not only has excellent chemical resistance and sticking resistance, but also can provide excellent image quality.

[0006]

The above objects of the present invention are to provide a heat-sensitive recording layer containing at least a color former and a color developer which comes into contact with the color former, and a protective layer on a support. A heat-sensitive recording material which is sequentially applied and dried, wherein the protective layer comprises at least a binder and 4 to 10 of a total solid content.
It was achieved by the heat-sensitive recording material and a manufacturing method thereof, characterized in that it contains% by weight of dodecyl benzenesulfonate.

In the heat-sensitive recording material of the present invention, an image is recorded by causing a color developer and a developer, which are isolated from each other at room temperature, to come into contact with each other by heating to form a color. As a color former and a color developer, a combination of an electron-donating dye precursor (color former) and an electron-accepting compound (color developer), or a combination of a diazo compound (color former) and a coupling compound (color developer) Is preferable, and when the former combination is employed, the effect of the present invention of greatly improving the stability of a printed image is remarkable.

The electron-donating dye precursor used in the present invention is not particularly limited, but has a property of donating electrons or accepting a proton such as an acid to form a color, and is preferably a lactone. , Lactams, sultones, spiropyrans, esters, amides, etc., are generally colorless compounds which have a partial skeleton which is opened or cleaved upon contact with a color developing agent.

A specific example is disclosed in Japanese Patent Application Laid-Open No. 55-2272.
No. 53 and the like. If some of these compounds are disclosed, 3,3-bis (p-dimethylaminophenyl) -6 is used as a triarylmethane compound.
-Dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,3 dimethylindole-3-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (2-methylindol-3-yl) phthalide and the like;

As the diphenylmethane-based compound, 4,
4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine, N-
2,4,5-trichlorophenylleuco auramine and the like;

The xanthene compounds include rhodamine-B-anilinolactam, rhodamine- (p-nitrino) lactam, 2- (dibenzylamino) fluoran,
2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-dibutylaminofluoran, 2-anilino-3-methyl-6-N-ethyl-N-isoamylaminofluoran, 2-anilino-
3-methyl-6-N-methyl-N-cyclohexylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-anilino-3-methyl-6
N-ethyl-N-isobutylaminofluoran, 2-anilino-6-dibutylaminofluoran, 2-anilino-3-methyl-6-N-methyl-N-tetrahydrofurfurylaminofluoran, 2-anilino-3 -Methyl-
6-piperidinoaminofluoran, 2- (o-chloroanilino) -6-diethylaminofluoran, 2- (3,
4-dichloroanilino) -6-diethylaminofluoran and the like;

Thiazine compounds such as benzoyl leucomethylene blue and p-nitrobenzyl leucomethylene blue; spiro compounds such as 3-methyl-spiro-dinaphthopyran and 3-ethyl-spiro-dinaphthopyran 3,3'-dichloro-spiro- Zinaphthopyran, 3
-Benzylspiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzopyran and the like.

As the electron accepting compound (developing agent) for these color formers, phenol compounds, organic acids or metal salts thereof, and acidic substances such as oxybenzoic acid esters are used. In particular, phenolic compounds or salicylic acid derivatives are used. And polyvalent metal salts thereof.

As the phenolic compound, for example,
2′-bis (4-hydroxyphenyl) propane, 4-
t-butylphenol, 4-phenylphenol, 4-
Hydroxydiphenoxide, 1,1′-bis (3-chloro-4-hydroxyphenyl) cyclohexane,
1'-bis (3-chloro-4-hydroxyphenyl)-
2-ethylbutane, 4,4'-sec-isooctylidenediphenol, 4,4'-sec-butylidenediphenol, 4-tert-octylphenol, 4-p-
Examples include methylphenylphenol, 4,4'-methylcyclohexylidenephenol, 4,4'-isopentylidenephenol, benzyl p-hydroxybenzoate and the like.

Examples of the salicylic acid derivative include, for example, 4-
Pentadecylsalicylic acid, 3,5-di (α-methylbenzyl) salicylic acid, 3,5-di (ter-octyl) salicylic acid, 5-octadecylsalicylic acid, 5-α- (p
-Α-methylbenzylphenyl) ethylsalicylic acid, 3
-Α-methylbenzyl-5-ter-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid,
-Decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid and the like, and zinc, aluminum, calcium, copper and lead salts thereof.

In particular, when a phenolic compound is used, the effect of suppressing background fog is remarkable. Examples of such a heat-sensitive recording material in which an electron-donating dye precursor (color former) and an electron-accepting compound (color developer) are combined include, for example,
U.S. Pat. Nos. 4,771,034 and 4,839,332
JP-A-63-22682, JP-A-63-2656
No. 82, 63-227375, JP-A-1-10
No. 5782 discloses this in detail.

The diazo compound which can be used in the present invention is a compound which reacts with a developer called a coupling component described later to form a desired hue and emits light of a specific wavelength before the reaction. It is a photo-decomposable diazo compound that decomposes when it receives it and no longer has a color-forming ability even when a coupling component acts.

The hue in this color forming system is mainly determined by the diazo dye formed by the reaction between the diazo compound and the coupling component. Therefore, as is well known,
The color hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupling component, and a substantially arbitrary color hue can be obtained depending on the combination.

The photo-decomposable diazo compound in the present invention mainly refers to an aromatic diazo compound, and more specifically refers to compounds such as aromatic diazonium salts, diazosulfonate compounds, and diazoamino compounds. Details of these diazo compounds are described in, for example, JP-A-2-136286.

Coupling components which form a dye by coupling with a diazo compound (diazonium salt) used in the present invention include, for example, 2-hydroxy-3-naphthoic acid anilide, resorcinol and the like. -14
No. 6678 can be mentioned. Further, an image of any color tone can be obtained by using two or more of these coupling components in combination.

Since the coupling reaction between the diazo compound and the coupling component easily occurs in a basic atmosphere, it is preferable to add a basic substance to the layer. Specific examples of these basic substances are described, for example, in JP-A-61-29
No. 1183. Two or more basic substances may be used in combination. Thermal recording materials using a combination of the above diazo compound (color former) and coupling compound (color developer) are described in, for example, JP-B-2-28479 and JP-B-2-28479.
Nos. 31,674 and 2,020,434.

The color former or the developer used in the present invention can be usually used in the form of a solid dispersion, but from the viewpoint of the raw storage stability of the heat-sensitive recording layer such as to prevent the contact between the color developer and the developer at room temperature. In the present invention, one of the color former and the developer, particularly the color former is used by being encapsulated in a microcapsule from the viewpoints of (fogging prevention) and control of the color development sensitivity of causing color development with desired thermal energy. Is preferred.

For the production of the microcapsules usable in the present invention, any of an interfacial polymerization method, an internal polymerization method and an external polymerization method can be employed. In particular, a core containing a color former is preferably used. It is preferable to employ an interfacial polymerization method in which a substance is emulsified in an aqueous solution in which a water-soluble polymer is dissolved, and then walls of the polymer substance are formed around the oil droplets.

The reactant forming the polymer substance is added inside the oil droplet and / or outside the oil droplet. Specific examples of the polymer substance include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer and the like. Preferred polymeric substances are polyurethanes, polyureas, polyamides, polyesters, polycarbonates, particularly preferably polyurethanes and polyureas. Two or more polymer substances can be used in combination.

Specific examples of the water-soluble polymer include gelatin, polyvinylpyrrolidone, and polyvinyl alcohol. The details of the method for producing the microcapsule composite wall are described in, for example, JP-A-58-66948. In order to microencapsulate the color former, it is preferable to use the color former dissolved in an organic solvent.

Examples of such organic solvents include low-boiling solvents such as ethyl acetate, methyl acetate, carbon tetrachloride, chloroform, methanol, ethanol, n-butanol, dioxane, acetone and benzene, and phosphoric acid esters and phthalic acid esters. Examples include high-boiling solvents such as carboxylic acid esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylnaphthalenes, and diarylethanes. Such an organic solvent is described in detail in JP-A-4-19778.

In the case of a microcapsule containing a color former, a solid sensitizer for swelling the microcapsule wall when heated can be further added. As the solid sensitizer, those which have a melting point of 50 ° C. or higher, preferably 120 ° C. or lower and are solid at ordinary temperature can be selected from those called polymer plasticizers used as microcapsule walls. For example, when the wall material is made of polyurea or polyurethane, a hydroxy compound, a carbamate compound, an aromatic alkoxy compound, an organic sulfonamide compound, an aliphatic amide compound, an arylamide compound, or the like is preferably used.

In the present invention, when a diazo compound is used as a color former, a color former may be used. The color-forming auxiliary that can be used in the present invention is a substance that increases the color density at the time of heating printing or lowers the minimum color-forming temperature, lowers the melting point of a coupling component or a diazo compound, or reduces the capsule wall. The purpose is to create a situation in which the diazo compound and the coupling component easily react by the action of lowering the softening point.

In the present invention, when the developer is not microencapsulated, the transparency of the heat-sensitive recording layer is improved, the light transmittance of the heat-sensitive recording material is improved, and the heat-sensitive recording material used for OHP is obtained. Or, from the viewpoint of laminating multiple heat-sensitive layers into a multicolor heat-sensitive recording material, after dissolving in a water-insoluble or insoluble organic solvent, this contains a surfactant and protects the water-soluble polymer. It can also be used in the form of a dispersion which is mixed with an aqueous phase having a colloid and emulsified and dispersed.

The organic solvent used in this case can be appropriately selected from high-boiling oils. Among them, preferred oils include esters, dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl, diisobutylbiphenyl, 1-methyl-1-dimethylphenyl-1-phenylmethane,
-Ethyl-1-dimethylphenyl-1-phenylmethane, 1-propyl-1-dimethylphenyl-1-phenylmethane, triallylmethane (eg, tritolylmethane, toluyldiphenylmethane), terphenyl compound (eg, terphenyl) , Alkyl compounds, alkylated diphenyl ethers (eg, propyl diphenyl ether), hydrogenated terphenyls (eg, hexahydroterphenyl), diphenyl ether, and the like.

Of these, esters are particularly preferred from the viewpoint of the emulsion stability of the emulsified dispersion. Esters include phosphates, phthalates, dioctyl tetrahydrophthalate, benzoates, abietic esters, dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalate, diethyl malonate, maleate , Tributyl citrate, sorbate, sebacate, ethylene glycol esters, triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, borate and the like.

Specific examples of these esters include, for example,
It is described in JP-A-4-371887. In particular, it is preferable to use tricresyl phosphate alone or as a mixture, since the emulsification and dispersion stability of the color developer is particularly good. The above oils can be used together or in combination with other oils. In the present invention, an auxiliary solvent may be further added to the above-mentioned organic solvent as a low boiling point dissolution aid. As such auxiliary solvents, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase containing these components is appropriately selected from known anionic polymers, nonionic polymers and amphoteric polymers. However, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable. As the surfactant to be contained in the aqueous phase, a surfactant which does not cause precipitation or aggregation by acting with the above protective colloid can be appropriately selected from anionic or nonionic surfactants. Preferred surfactants include
Examples thereof include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sodium sulfosuccinate, and polyalkylene glycol (for example, polyoxyethylene nonyl phenyl ether).

The emulsified dispersion of the present invention is prepared by mixing an oil phase containing the above components, a protective colloid, and an aqueous phase further containing a surfactant, if necessary, with high-speed stirring, ultrasonic dispersion, or the like.
It can be easily obtained by mixing and dispersing using the means usually used for emulsification of fine particles. The ratio of the oil phase to the aqueous phase (oil phase weight / water phase weight) is 0.0
It is preferably 2 to 0.6, particularly 0.1 to 0.4
It is preferred that If it is less than 0.02, the aqueous phase is too large to be diluted, and sufficient color development cannot be obtained. If it is more than 0.6, the viscosity of the liquid becomes higher, which causes inconvenience in handling and lowers the stability of the coating liquid.

In the present invention, a heat-fusible substance can be contained in the heat-sensitive coloring layer in order to improve the thermal response of the heat-sensitive recording material. Examples of preferred heat-fusible materials include benzyl p-benzyloxybenzoate, β-naphthyl-benzyl ether, stearamide, stearyl urea, p-benzylbiphenyl, di (2-methylphenoxy) ethane, di (2 -Methoxyphenoxy) ethane, β-naphthol- (p-methylbenzyl) ether, α-naphthylbenzyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-tert-octylphenyl ether,
1-phenoxy-2- (4-ethylphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1,4-butanediol phenyl ether, diethylene glycol-bis (4-methoxyphenyl) ether, and the like. Can be

The heat-fusible substance may be used alone or as a mixture. In order to obtain sufficient thermal responsiveness, it is preferable to use the heat-fusible substance in an amount of 10 to 200% by weight, particularly preferably 20 to 150% by weight, based on the developer. Further, the thermosensitive recording layer may further include, if necessary,
Pigments, metal soaps, waxes, antistatic agents, ultraviolet absorbers, surfactants, defoamers, conductive agents, fluorescent paints and the like may be added.

As the pigment, calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica, amorphous silica, aluminum hydroxide and the like are used. As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, and aluminum stearate.

As wax, paraffin wax,
Microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax, fatty acid amide wax and the like are used alone or in combination. As a surfactant,
An alkali metal salt of sulfosuccinic acid and a fluorine-containing surfactant are used. The coating amount of the heat-sensitive coloring layer is not particularly limited, but is usually 1 to 10 g / dry weight.
m ² , preferably in the range of ^{2 to} 8 g / m ² .

The most significant feature of the heat-sensitive recording material of the present invention resides in that a protective layer containing an alkylbenzene sulfonate is provided on the heat-sensitive recording layer. As such an alkylbenzene sulfonate, an alkali metal salt, an ammonium salt or a triethanolamine salt of an alkylbenzenesulfonic acid represented by the following formula 1 is particularly preferable.

[0040]

Embedded image R in Chemical Formula 1 represents an alkyl group. R represents C _{3 to} C ₂₀
Are preferred, and a C ₄ -C ₁₂ alkyl group is particularly preferred.

[0041] The addition amount of dodecyl benzene sulfonate to be added to the protective layer solution, 4-10% by weight of the total solids, preferably 4 to 8% by weight. If the amount is less than 4% by weight, it may not be possible to form a uniform protective layer, resulting in insufficient print quality and anti-sticking performance. On the other hand, if the addition amount is more than 10% by weight, bubbling becomes large, and the penetration of the protective layer liquid into the heat-sensitive recording layer becomes large, resulting in a non-uniform protective layer.

In the present invention, the binder for the protective layer containing an alkylbenzene sulfonate includes polyvinyl alcohol, carboxy-modified polyvinyl alcohol, gelatin or derivatives thereof, starch and derivatives thereof, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose and the like. Cellulose derivatives, casein, sodium alginate, sodium polyacrylate, polyacrylamide, salts of styrene-maleic acid copolymers, self-crosslinkable acrylic resin emulsions, polyurethane resins, latexes such as styrene / butadiene / acrylic copolymers are used. Can be In this case, a water-proofing agent can be used in combination. In the present invention, it is particularly preferable to use a fluorine-based surfactant in combination.

In the protective layer, for the purpose of improving matching with a thermal head during thermal recording and improving water resistance,
Pigments, metal soaps, waxes, crosslinking agents and the like are added. Details of these pigments, metal soaps, waxes, crosslinking agents and the like are described in, for example, JP-A-2-141279. Examples of the pigment include calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, kaolin, talc, clay and the like.
Pigments of 100 g or less are preferred.

The protective layer solution containing the alkyl benzene sulfonate may be mixed with a mixer, a dissolver,
After being sufficiently mixed and dispersed by a stirring, mixing and dispersing device such as an attritor or a sand mill, it is applied on the heat-sensitive recording layer. When applying the protective layer solution or the heat-sensitive layer solution prepared as described above on a support or a heat-sensitive recording layer, a known aqueous or organic solvent-based coating solution is used.

The coating amount of the protective layer is not particularly limited. However, if it is less than 0.1 g / m ² , the desired effect cannot be obtained, and if it exceeds 10 g / m ² , the recording sensitivity may be significantly reduced. Is generally 0.1 g / m to 10 g / m
² , preferably in the range of 1 to 5 g / m ² .

The protective layer, like the heat-sensitive recording layer, is formed by a conventionally known coating method, for example, air knife coating,
It is applied by blade coating, gravure coating, bar coating, spray coating, dip coating, curtain coating, etc.Among them, the curtain coating method of forming a free-falling curtain film and applying it to a running support to be applied, This is preferable because a defective surface due to bubbles does not occur and a uniform protective layer can be formed. The applied heat-sensitive recording material is dried, subjected to a treatment such as a calender, and provided for use.

The support used in the present invention may be transparent or opaque. Opaque supports include paper, coated paper, synthetic paper, paper laminated with polymer film, aluminum vapor-deposited base, polymer film coated with white pigment, etc. For this purpose, it is preferable to provide an undercoat layer containing a pigment and a binder as main components.

Examples of the transparent support include polyester films such as polyethylene terephthalate and polybutylene terephthalate; cellulose derivative films such as cellulose triacetate film; polyolefin films such as polystyrene film, polypropylene film and polyethylene film; polyimide films; Examples include a vinyl film, a polyvinylidene chloride film, a polyacrylic acid copolymer film, and a polycarbonate film, and these can be used alone or in combination, and particularly those obtained by subjecting a polyester film to a heat treatment and an antistatic treatment. Is preferred. The support has a thickness of 20 to 200 μm, and particularly preferably 50 to 1 μm.
Those having a size of 00 μm are preferred.

[0049]

Since the heat-sensitive recording material of the present invention has a protective layer containing an alkylbenzene sulfonate on the heat-sensitive recording layer, the heat-sensitive recording material has improved storage stability and anti-sticking performance and excellent head matching. It is.
Further, by forming the protective layer by the curtain coating method, it is possible to improve the printing quality.

[0050]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Unless otherwise specified, parts and% described below
Represents parts by weight and% by weight, respectively.

Embodiment 1 (Formation of Thermal Recording Layer) Preparation of Solution A 10 parts of 3-butylamino-6-methyl-7-anilinofluoran and a 5% solution of polyvinyl alcohol (PVA)
-105: a liquid having a composition of 50 parts by a Kuraray Co., Ltd. having a mean particle diameter of 1.0 μm by a sand mill
Was obtained.

Preparation of Solution B 20 parts of bisphenol A, naphthyl benzyl ether 2
Using a liquid having a composition of 0 parts and 200 parts of polyvinyl alcohol, a dispersion having an average particle diameter of 1.0 μm was obtained by a sand mill.

Preparation of Liquid C Using a liquid composed of 40 parts of light calcium carbonate, 1 part of sodium polyacrylate and 60 parts of water, a pigment dispersion having an average particle diameter of 2.0 μm was obtained by a sand mill. Liquid A 6
0 parts, 240 parts of solution B, 101 parts of solution C and 25 parts of a 21% zinc stearate dispersion were mixed to obtain a coating solution for a thermosensitive recording layer. The obtained heat-sensitive recording layer coating solution was applied to an undercoat base paper of 50 g / m ² provided with an undercoat layer mainly composed of a pigment and a binder by an air knife coat so that the coating amount was 5 g / m ^2. After drying, a heat-sensitive recording layer was obtained.

(Formation of thermosensitive recording material) Preparation of protective layer solution 200 parts of 10% aqueous starch oxide solution, 20 parts of aluminum hydroxide, 19 parts of a dispersion of 21% zinc stearate, 2 parts of sodium dodecylbenzenesulfonate and 65 parts of water Was obtained. The obtained protective layer liquid was applied on the above-mentioned heat-sensitive recording layer with an air knife coat at 3 g / m ² and dried to obtain a heat-sensitive recording material.

Embodiment 2 FIG. Instead of the protective layer solution used in Example 1, 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, and 21% of zinc stearate dispersion 1
A heat-sensitive recording material was obtained in exactly the same manner as in Example 1, except that a protective layer solution consisting of 9 parts, 2 parts of triethanolamine dodecylbenzenesulfonate, and 65 parts of water was used.

Embodiment 3 FIG. Instead of the protective layer solution used in Example 1, 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, and 21% of zinc stearate dispersion 1
9 parts, ammonium dodecylbenzenesulfonate 2 parts,
A heat-sensitive recording material was obtained in exactly the same manner as in Example 1, except that a protective layer liquid consisting of 65 parts of water was used.

Comparative Example 1 Instead of the protective layer solution used in Example 1, it was composed of 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, 19 parts of a dispersion of 21% zinc stearate, 1 part of sodium dodecylbenzenesulfonate, and 65 parts of water. A thermosensitive recording material was obtained in exactly the same manner as in Example 1 except that the protective layer liquid was used.

Embodiment 4 FIG. Example 1 was repeated except that the protective layer liquid was applied onto the heat-sensitive recording layer with a free-fall curtain coat to a concentration of 3 g / m ² and dried.
A thermosensitive recording material was obtained in exactly the same manner as described above.

Comparative Example 2 A protective layer solution consisting of 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, 19 parts of a dispersion of 21% zinc stearate, and 65 parts of water was used in place of the protective layer solution used in Example 1. In the same manner as in Example 1, a heat-sensitive recording material was obtained.

Comparative Example 3 Instead of the protective layer solution used in Example 1, 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, β
2 parts of sodium salt of a formalin condensate of naphthalenesulfonic acid, 19 parts of a 21% dispersion of zinc stearate, and 65 parts of water
A heat-sensitive recording material was obtained in exactly the same manner as in Example 1, except that a protective layer solution consisting of parts was used.

Comparative Example 4 Instead of the protective layer liquid used in Example 1, it was composed of 200 parts of a 10% aqueous solution of starch oxide, 20 parts of aluminum hydroxide, 2 parts of polyoxyethylene lauryl ether, 19 parts of a dispersion of 21% zinc stearate, and 65 parts of water. A thermosensitive recording material was obtained in exactly the same manner as in Example 1 except that the protective layer liquid was used.

The evaluation results of the heat-sensitive recording materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below.

[Table 1] The dynamic sensitivity, image quality, sticking, and chemical resistance in the table were measured as follows.

Method for measuring sensitivity Thermal head (KLT-216- manufactured by Kyocera Corporation)
8MPD1) and a thermal printing apparatus having a pressure of 100 kg / cm ² immediately before the head, printing with a pulse width of 1.2 ms using a pressure roll under the conditions of a head voltage of 24 V and a pulse period of 10 ms, and the print density thereof Was measured with a Macbeth reflection densitometer RD-918.

Evaluation Method of Image Quality The above print samples were visually evaluated, and the criteria were as follows. ◎ ------- Excellent. ○ −−−−− Excellent. Δ −−−−− Inferior. × −−−−− Very poor.

Evaluation method of sticking : Printing was performed using Xerox-TC7005, and whiteout and printing sound were evaluated according to the following criteria. −−−−−− No printing noise and no overexposure. Δ −−−−− Slight overexposure occurred and printing noise was found (practically usable). × −−−−− There are many overexposed areas and the printing sound is loud.

Evaluation Method for Chemical Resistance Writing was performed with a fluorescent pen (Zebra Highlighter 2-Pink), and the fog on the surface of the heat-sensitive recording material was visually evaluated. The criteria were as follows. ○ ---- No fog is observed. Δ −−−−− Slight fog is observed. × −−−−− Fog is clearly seen. As is clear from the results in Table 1, the heat-sensitive recording materials obtained in the examples of the present invention have improved storage stability and anti-sticking properties, have excellent head matching properties, and have high image quality. there were.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-253391 (JP, A) JP-A-3-61077 (JP, A) JP-A-3-169587 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A heat-sensitive recording layer comprising at least a color former and a color developer which is colored upon contact with the color former, on a support.
And a protective layer formed by sequentially applying and drying a protective layer, wherein the protective layer contains at least a binder and 4 to 10% by weight of the total solids of dodecylbenzene sulfonate. Thermal recording material. Wherein dodecyl benzene sulfonate, de de
Shi Le alkali metal salts of benzenesulfonic acid is at least one selected from among triethanolamine salts and ammonium salts, heat-sensitive recording material according to claim 1. 3. A heat-sensitive recording layer containing at least a color-forming agent and a color developing agent that forms a color in contact with the color-forming agent is provided on a support, and then the heat-sensitive recording layer has a solid content of at least 4 to 4%.
A method of manufacturing a heat-sensitive recording material having a protective layer containing a water-soluble resin as a 10 wt% of dodecyl benzene sulfonate and a binder, the protective layer, and wherein applying the free-falling curtain coating method Method for producing a heat-sensitive recording material.