JP2002113947A - Thermal recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording body excellent in the adhesion of an anchor coat layer to a substrate and a thermal recording layer and in the swell resistance of the anchor coat layer to a plasticizer. SOLUTION: In the thermal recording body having the anchor coat layer constituted mainly of a hydrophobic resin and the thermal recording layer containing leuco dye, a development and an adhesive on the substrate sequentially, the swell of the anchor coat layer with dioctyl phthalate(DOP) is made 30% or less as one means for attaining the purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium utilizing a color-forming reaction between a leuco dye and a color former.

[0002]

2. Description of the Related Art A thermosensitive recording medium utilizing a color-forming reaction between a leuco dye and a coloring agent has a compact recording device which is inexpensive and easy to maintain. It is widely used as a recording medium for outputs such as CRT medical measuring instruments.

[0003] For example, a thermal recording medium using a resin film as a support is used for a cash card, a commuter pass, or the like. In order to solidify the adhesiveness of the thermal recording layer to the resin film surface, the thermal recording medium is coated on the surface of the resin film. A heat-sensitive recording medium having an anchor coat layer containing a hydrophobic resin as a main component and a heat-sensitive recording layer provided on the surface thereof is described in JP-A-3-239585. There is a problem that the anchor coat layer swells due to a plasticizer or hand oil during the commuter pass and the heat-sensitive recording layer peels off.

Further, in order to enhance the recording sensitivity of the thermosensitive recording medium, a thermosensitive recording medium using a leuco dye and a coloring agent finely dispersed to have an average particle diameter of about 1 μm is disclosed in JP-A-6-286315 and JP-A-8-286. Although described in JP-A-324115, there is a problem that the recording density is reduced when the thermosensitive recording medium is immersed in water, or the thermosensitive recording layer is peeled off from the support.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording medium having excellent adhesion of an anchor coat layer to a support and a heat-sensitive recording layer, and having excellent resistance to swelling of a plasticizer in the anchor coat layer. To provide.

[0006]

According to the present invention, there is provided a thermosensitive recording medium having, on a support, an anchor coat layer containing a hydrophobic resin as a main component and a thermosensitive recording layer containing a leuco dye, a coloring agent and an adhesive in order. As one means for solving the above problem, the degree of swelling of the anchor coat layer with respect to dioctyl phthalate (DOP) is set to 30% or less.

Further, by using an emulsion-polymerized acrylic resin as a hydrophobic resin in the anchor coat layer or using a resin film, particularly a polyethylene terephthalate film, as a support, the adhesion to the support can be improved. The effect is further enhanced, and the effect of extremely excellent swelling resistance of the anchor coat layer against the plasticizer is obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An anchor coat layer containing a hydrophobic resin as a main component and provided on a support to enhance the adhesion of a heat-sensitive recording layer to the support, a leuco dye, a colorant and an adhesive Is characterized in that the degree of swelling of the anchor coat layer with respect to dioctyl phthalate (DOP) is 30% or less, more preferably about 3 to 25%. When the degree of swelling exceeds 30%, the anchor coat layer swells due to the action of a plasticizer contained in a commuter pass or sweat, hand oil or the like while the thermosensitive recording medium is used for a long period of time. There is a possibility that the recording medium is peeled off from the anchor coat layer or the heat-sensitive recording layer. If the degree of swelling is less than 3%, the adhesion of the anchor coat layer to the support may decrease.
The swelling degree of the support itself with respect to dioctyl phthalate (DOP) is preferably 20% or less.

The swelling degree of the anchor coat layer is 40 to
After drying the coating liquid for an anchor coat layer on one surface of a 200 μm aluminum foil (10 cm × 10 cm, weight W ₁ ), the anchor coat layer is dried (at 50 ° C. for 5 hours) to have a thickness of 5 to 20 μm. 20 samples (weight W ₂ )
When immersed in dioctyl phthalate (DOP) at 24 ° C., that is, di (2-ethylhexyl) phthalate for 24 hours, and the DOP attached to the sample surface is wiped off with tissue paper, the weight is defined as W _3. , [(W ₃ −W ₁ ) − (W ₂
−W ₁ )] / (W ₂ −W ₁ ) multiplied by 100.

In order to make the degree of swelling of the anchor coat layer 30% or less, it is preferable to use, for example, those having a degree of swelling of 30% or less as a hydrophobic resin contained as a main component in the anchor coat layer. Examples of the hydrophobic resin having a swelling degree of 30% or less include those having a molecular weight of 200,000 or more, those three-dimensionally polymerized, and those whose cross-linking density is increased by a cross-linking agent.

The content of the hydrophobic resin in the anchor coat layer is at least 30% by weight, preferably at least 50% by weight, based on the total solid content of the anchor coat layer. If the content of the hydrophobic resin is less than 30% by weight, the adhesion of the anchor coat layer to the support may be reduced.

The hydrophobic resin in the anchor coat layer includes, for example, three-dimensionally polymerized acrylic resin, styrene resin, urethane resin, vinyl acetate resin and the like. Acrylic resins are preferred because of their excellent swelling resistance.

In the anchor coat layer, white inorganic pigments such as titanium oxide, calcium carbonate, and aluminum hydroxide having an average primary particle diameter of about 0.1 to 2 μm, white organic pigments such as plastic pigment, or Colored organic pigments and dyes can also be included.

As the support, for example, a thickness of 40 to 3
Paper of about 00 μm, synthetic paper, resin film and the like can be mentioned. Specific examples of the resin film include a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polystyrene film, a polyethylene terephthalate (PET) film, and the like. Among them, a polyethylene terephthalate film is preferable because of its excellent adhesion to the anchor coat layer.

The resin film may be unstretched or biaxially stretched. Further, in the resin film, titanium oxide, calcium carbonate, aluminum hydroxide and the like having an average primary particle diameter of about 0.1 to 2 μm are contained. White inorganic pigment,
Alternatively, a colored organic pigment or dye may be internally added.
The surface of the resin film may be subjected to corona discharge treatment in order to further enhance the adhesion between the resin film and the anchor coat layer.

The anchor coat layer is prepared by mixing and stirring, for example, an emulsion-polymerized acrylic resin-based latex and, if necessary, an auxiliary agent such as a pigment or a surfactant, using water or an organic solvent as a medium. It is obtained by applying and drying the application coating liquid on a support so that the applied amount after drying is about 0.1 to 10 g / m ² .

Further, a coating liquid for an anchor coat layer containing a compound which is three-dimensionally polymerized by irradiation of ultraviolet rays or electron beams as a main component is applied to a support, and then a cured anchor coat layer is formed by irradiation of ultraviolet rays or electron beams. You can also.

Various known leuco dyes and colorants can be used in the heat-sensitive recording layer. Specific examples of such leuco dyes include, for example, 3,3-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-di Blue-color-forming dyes such as benzylamino-benzo [a] fluoran; 3- (N-ethyl-Np-tolyl) amino-7-
N-methylanilinofluoran, 3-diethylamino-
Green-coloring dyes such as 7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-cyclohexylamino-6-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-
Red-coloring dyes such as diethylamino-7-chlorofluoran, rhodamine (o-chloroanilino) lactam, 3-diethylamino-6,8-dimethylfluoran,
-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino -6-methyl-7-anilinofluoran, 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 3-di (n-amyl) amino-6-methyl-7-ani Rinofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran,
3-di (n-butyl) amino-7- (o-fluoroanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tetrahydrofurfurylamino) -6
Methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-ani A black color-forming dye such as linofluorane; 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3-p- (p-dimethylaminoanilino) anilino-6
-Methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluoran, 3,6-bis (dimethylamino) fluorene-9
And dyes having an absorption wavelength in the near infrared region, such as -spiro-3 '-(6'-demethylamino) phthalide.

Examples of the coloring agent include 4,4'-isopropylidenediphenol, 4,4'-cyclohexylidenediphenyl and 1,1-bis (4-hydroxyphenyl).
-Ethane, 1,1-bis (4-hydroxyphenyl)-
1-phenylethane, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone , Np-toluenesulfonyl-
N′-3- (p-toluenesulfonyloxy) phenylurea, benzyl 4-hydroxybenzoate,
N, N'-di-m-chlorophenylthiourea, Np-
Tolylsulfonyl-N'-phenylurea, 4,4'-
Bis (p-tolylsulfonylaminocarbonylamino)
Diphenylmethane, 4- [2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 4- {3- (p-
Tolylsulfonyl) propyloxy] zinc salicylate,
5- [p- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate;

Of course, the leuco dye and the color former are not limited to these, and two or more of them can be used in combination as needed. The use ratio of the leuco dye and the color former is appropriately selected depending on the type of the leuco dye and the color former used, and is not particularly limited, but is generally 1 part by weight of a colorless or pale color leuco dye. The color former is used in an amount of 1 to 10 parts by weight, preferably 1 to 5 parts by weight.

The heat-sensitive recording layer uses water as a dispersion medium, and separates the leuco dye and the color former together with the dispersant with a pulverizer such as an attritor or a sand mill, for example, to have a mean particle size of 0.1.
After finely dispersing to about 1 to 2.0 μm, an adhesive,
And applying and drying the heat-sensitive recording layer coating solution prepared by adding the following auxiliaries as necessary so that the coating amount after drying is about 3 to 15 g / m ^{2 on} one surface of the resin film. Is done.

Examples of the adhesive in the coating solution for the thermosensitive coloring layer include partially (completely saponified) saponified polyvinyl alcohol,
Carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, gelatin, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, polyvinylpyrrolidone, acrylamide-acrylate Copolymer, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer,
Examples include water-soluble adhesives such as isobutylene-maleic anhydride copolymer, casein, and gelatin, as well as vinyl acetate resins, urethane resins, acrylic resins, styrene resins, and styrene-butadiene latex.

Examples of the auxiliary agent that can be added to the coating solution for the heat-sensitive recording layer include lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, calcium carbonate, zinc oxide, and aluminum oxide. , Titanium dioxide, amorphous silica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined clay, inorganic pigments such as colloidal silica, styrene microballs, nylon powder, polyethylene powder, and organic such as urea / formalin resin filler Crosslinking agents such as pigments, glyoxal, dimethylol urea, polyamide epichlorohydrin, boric acid, borax, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′- tert-butyl Eniru) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di -tert-
Examples include ultraviolet absorbers such as (butylphenyl) benzotriazole, other surfactants, fluorescent dyes, coloring pigments, coloring dyes, and the like.

The heat-sensitive recording layer may further contain a sensitizer for further improving the recording sensitivity and a storability improving agent for improving the storability of the recording portion. As a sensitizer,
For example, 1,2-di (3-methylphenoxy) ethane,
1,2-diphenoxyethane, parabenzylbiphenyl, naphthylbenzyl ether, benzyl-4-methylthiophenyl ether, 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid di-p-methylbenzyl Ester, oxalic acid-
Examples thereof include di-p-chlorobenzyl ester, dibutyl terephthalate, dibenzyl terephthalate, and dibutyl isophthalate.

As the preservability improver, for example,
4′-butylidenebis (6-tert-butyl-3-methylphenol), 2,2′-methylenebis (4-ethyl-
6-tert-butylphenol), 2,4-di-tert-butyl-3-methylphenol, 1,1,3-tris (2
-Methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,
3,5-tris (5-tert-butyl-3-hydroxy-
Hindered phenols such as 2,6-dimethylbenzyl) isocyanuric acid; 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, 4- (2-ethyl-)
Diphenylsulfone derivatives having an epoxy group such as 1,2-epoxyethyl) diphenylsulfone and 4-benzyloxy-4 ′-(2,3-glycidyloxy) diphenylsulfone; 2- (2′-hydroxy-5′-methyl) Phenyl) benzotriazole, 2-hydroxy-4-
UV absorbers such as benzyloxybenzophenone.

The average particle size of the auxiliary, sensitizer and storage stability improver which can be contained in the heat-sensitive recording layer is preferably 2 μm or less. The amount of the sensitizer and the color former is about 0.5 to 4 parts by weight based on 1 part by weight of the leuco dye.

By further containing an ammonium salt of a styrene-methacrylic acid copolymer as an adhesive in the heat-sensitive recording layer, the adhesiveness between the anchor coat layer and the heat-sensitive recording layer can be further increased, and the heat-sensitive recording layer can be used like a commuter pass. Even when the recording layer is used for a long time, the effect that the heat-sensitive recording layer is hardly peeled off from the anchor coat layer is obtained.

The ammonium salt of the styrene-methacrylic acid copolymer preferably has a molecular weight of about 1,000 to 50,000, particularly preferably about 5,000 to 40,000. If the molecular weight is smaller than this, the adhesion to the resin film or the stability of the colorant dispersion is inferior, and if the molecular weight is larger than this, the viscosity of the colorant dispersion becomes too high, and the Efficiency decreases.

The ammonium salt of the styrene / methacrylic acid copolymer is preferably a copolymer in which the molar ratio of styrene and methacrylic acid monomers is about 10: 1 to 10. Other monomers can be copolymerized as long as the desired effects of the present invention are not impaired. Other monomers include, for example, methyl acrylate, ethyl acrylate, butyl acrylate and the like.

On the heat-sensitive recording layer, it is preferable to provide a protective layer mainly composed of an organic polymer compound having an excellent film-forming property in order to further enhance the recording running property and the preservability of the recording portion against chemicals.

The protective layer is formed of an organic polymer compound having excellent film-forming properties, such as partially (completely) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, gelatin, casein, and the like. The coating amount of the protective layer coating solution prepared by mixing and stirring an aqueous solution and, if necessary, an auxiliary agent that can be added to the heat-sensitive recording layer coating solution, is applied onto the heat-sensitive recording layer in an amount of 1 to 6 g / m ^2. It is formed by coating and drying to a degree.

The method for applying the coating liquid for the anchor coat layer, the thermosensitive recording layer and the protective layer is not particularly limited.
For example, methods such as air knife coating, blade coating, die coating, curtain coating, slide bead coating and the like can be mentioned.

After the heat-sensitive recording layer is coated and dried, it may be subjected to a smoothing treatment such as super calendering, if necessary, or a gloss layer cured by irradiating an ultraviolet ray or an electron beam on the protective layer may be provided. Various known techniques relating to the production of a thermosensitive recording medium, such as providing a conductive layer and a magnetic recording layer on the other surface of the transparent support, can be added.

[0034]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Unless stated otherwise, “parts” and “%”
The terms “parts by weight” and “% by weight” are respectively represented.

Example 1 Preparation of black particle-forming leuco dye-containing composite particle dispersion 3-di (n-amyl) amino-6-methyl-7-anilinofluoran 10 as a black-coloring electron-donating compound
Part was heated to 100 ° C., dicyclohexylmethane-4,
Dissolve in 40 parts of 4'-diisocyanate,
After cooling to 5 ° C., the mixture was gradually added to 200 parts of an aqueous solution of 8% polyvinyl alcohol (trade name: Gohsenol GM-14L, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) at the same temperature. The mixture was emulsified and dispersed by stirring at a rotation speed of 4,000 rpm, and 80 parts of water was added to the emulsified dispersion to homogenize. The temperature of the emulsified dispersion was raised to 80 ° C., a curing reaction was carried out for 10 hours, water was added at room temperature so as to have a solid concentration of 20%, and a black color-forming leuco dye having an average particle size of 1.0 μm. A composite particle dispersion was prepared.

Preparation of Red Coloring Leuco Dye Dispersion 36 parts of 3-diethylamino-7-chlorofluorane, 20% aqueous solution of ammonium salt aqueous solution of styrene / methacrylic acid copolymer (trade name: Polymalon 1308S, Arakawa Chemical Industries, Ltd.) A composition comprising 20 parts of water and 50 parts of water was pulverized with a sand mill until the average particle diameter became 1.2 μm to obtain a red color-forming leuco dye dispersion.

Preparation of Coloring Agent Dispersion 36 parts of Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea and 20 parts of an aqueous ammonium salt solution of a styrene / methacrylic acid copolymer
% Aqueous solution (trade name: Polymaron 1308S, manufactured by Arakawa Chemical Industry Co., Ltd.) and 30 parts of water are pulverized by a sand mill until the average particle diameter becomes 0.8 μm, and the colorant dispersion is dispersed. I got

Preparation of sensitizer dispersion: di-p-oxalate
A composition comprising 36 parts of methylbenzyl, 20 parts of a 20% aqueous solution of ammonium salt aqueous solution of styrene / methacrylic acid copolymer (trade name: Polymalon 1308S, manufactured by Arakawa Chemical Industry Co., Ltd.) and 30 parts of water was subjected to a sand mill. The mixture was pulverized until the average particle diameter became 1.2 μm to obtain a sensitizer dispersion.

Preparation of a preservative improver dispersion 36 parts of 4-benzyloxy-4 '-(2,3-glycidyloxy) diphenylsulfone, a 20% aqueous solution of an ammonium salt aqueous solution of a styrene / methacrylic acid copolymer (commercially available) Name: Polymeron 1308S, Arakawa Chemical Industry Co., Ltd.)
A composition comprising 20 parts and 44 parts of water was pulverized by a sand mill until the average particle diameter became 0.9 μm to obtain a sensitizer dispersion.

Preparation of coating liquid for anchor coat layer Acrylic resin having a solid concentration of 40% (trade name: Teisan Resin NFA830, manufactured by Teikoku Chemical Industry Co., Ltd.) 205
Part, plastic pigment having a solid content of 46% (trade name: Grosdale 104S, manufactured by Mitsui Chemicals, Inc.) 35
Part, 2 of polyamide epichlorohydrin resin (crosslinking agent)
A composition comprising 10 parts of a 0% aqueous solution and 150 parts of water was mixed and stirred to obtain a coating liquid for an anchor coat layer.

Preparation of Coating Solution for Thermosensitive Recording Layer 125 parts of a composite particle dispersion containing a black chromogenic leuco dye, 25 parts of a red chromogenic leuco dye dispersion, and a color former dispersion 65
Parts, sensitizer dispersion liquid 50 parts, storage stability improver dispersion liquid 10 parts,
Sodium di-2-ethylhexylsulfosuccinate 5
% Aqueous solution 3 parts, urethane resin 22 with 50% solid content
Part, 20% aqueous solution of ammonium salt aqueous solution of styrene / methacrylic acid copolymer (trade name: Polymalon 1308)
S, manufactured by Arakawa Chemical Industries, Ltd.) and 10 parts of a 20% aqueous solution of polyamide epichlorohydrin resin (crosslinking agent) were mixed and stirred to obtain a coating solution for a heat-sensitive recording layer.

Preparation of coating liquid for protective layer 10% aqueous solution of carboxy-modified polyvinyl alcohol 1
00 parts, polyamide epichlorohydrin resin (crosslinking agent)
10 parts of a 20% aqueous solution, 10 parts of aluminum hydroxide having an average particle diameter of 1 μm, 2 parts of a 30% dispersion of zinc stearate, and 10 parts of water were mixed and stirred to obtain a coating liquid for a protective layer.

Preparation of thermosensitive recording medium White polyethylene terephthalate film having a basis weight of 280 g / m ² (trade name: Lumirror E22, manufactured by Toray Industries, Inc.) was coated on one surface with a coating liquid for an anchor coat layer and a thermosensitive recording layer. The coating amount after drying the coating solution and the coating solution for the protective layer is 5.
0 g / m ² , 7.0 g / m ² , and 3.0 g / m ² are applied and dried successively to provide an anchor coat layer, a heat-sensitive recording layer, and a protective layer. Beck smoothness (JIS P 8119) of the layer surface is 8000
Second heat sensitive recording material was obtained.

Example 2 In the production of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
Acrylic resin with a solid content of 50% (trade name: Polysol AM)
-16 parts and water 1
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that a coating solution for anchor coat layer consisting of 91 parts was used.

Example 3 In the production of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
182 parts of polyester urethane resin (trade name: Hydran APX-101H, manufactured by Dainippon Ink and Chemicals, Inc.) and 173 parts of water instead of the coating liquid for anchor coat layer consisting of 45 parts by weight. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the coating solution for the anchor coat layer was used.

Example 4 In the preparation of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
Instead of the coating liquid for the anchor coat layer composed of the polyester resin having a solid content concentration of 25% (trade name: Gabsen E
S-210, manufactured by Teikoku Chemical Industry Co., Ltd.) A thermosensitive recording medium was obtained in the same manner as in Example 1, except that a coating liquid for an anchor coat layer consisting of 328 parts and water of 27 parts was used.

Comparative Example 1 In the preparation of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
Parts, instead of the coating liquid for the anchor coat layer consisting of a carboxylic acid-modified latex having a solid concentration of 41% and a urethane hybrid polymer (trade name: Pateracol H-209)
0, manufactured by Dainippon Ink and Chemicals, Inc.) and a thermosensitive recording medium was obtained in the same manner as in Example 1, except that a coating liquid for an anchor coat layer composed of 200 parts of water and 155 parts of water was used.

Comparative Example 2 In the preparation of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
Instead of the coating liquid for an anchor coat layer consisting of 186 parts of a styrene acrylic resin having a solid content concentration of 44% (trade name: Bonron S-1120, manufactured by Mitsui Chemicals, Inc.) and 169 parts of water A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the coating liquid for use was used.

Comparative Example 3 In the preparation of the thermosensitive recording medium of Example 1, the solid content concentration was 40
% Acrylic resin (trade name: Teisan Resin NFA8)
30, manufactured by Teikoku Chemical Industry Co., Ltd.) 205 parts and water 150
171 parts of a styrene-butadiene-based latex (trade name: 0623A, manufactured by JSR Corporation) having a solid content concentration of 48% and water 1
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that a coating liquid for an anchor coat layer consisting of 84 parts was used.

The coating liquid for anchor coat layer and the two-color heat-sensitive recording material thus obtained were subjected to the following evaluation tests, and the results are shown in Table 1.

The degree of swelling of the anchor coat layer with respect to dioctyl phthalate (DOP) The coating liquid for the anchor coat layer used in the two-color-developed thermosensitive recording medium shown in Table 1 was prepared using a 100-μm-thick aluminum foil (10 cm × 10 cm, weight is W _1, Tokaiarumihaku (Ltd.)
A sample (weight W ₂ ) provided with an anchor coat layer on one side of the surface of the coating liquid for drying the coating liquid for an anchor coat layer (at 50 ° C. for 5 hours) to have a thickness of 10 μm. In di (2-ethylhexyl) phthalate (DOP)
After soaking for a period of time, the DOP adhering to the surface of the sample is wiped off with tissue paper, and the weight (W ₃ ) is measured, and [(W ₃ −W ₁ ) − (W ₂ −W ₁ )] A value obtained by multiplying the value of / (W ₂ −W ₁ ) by 100 was calculated.

With respect to the two-color heat-sensitive recording material shown in Table 1, one-line recording time: 5 msec, sub-scanning line density: 8 lines / mm, using a thermal printing tester TH-PMD (manufactured by Okura Electric Co., Ltd.) Applied energy per dot: 256 under the condition of 0.5 mJ
The solid recording of the line was performed, and the red coloring recording was performed in the low-temperature recording section. Separately, one-line recording time: 5 ms
c, solid recording of 256 lines was performed under the conditions of a sub-scanning line density: 8 lines / mm and an applied energy per dot: 2.0 mJ, and black color recording was performed in a high-temperature recording section.
In all the heat-sensitive recording materials shown in Table 1, a clear red color was obtained in the low-temperature recording area, and a black color was obtained in the high-temperature recording area.

Plasticizer Resistance A wrap film (trade name: High Wrap SAS, manufactured by Mitsui Chemicals, Inc.) is wound three times on a polycarbonate pipe (outer diameter: 40 mm), and a two-color thermosensitive recording medium is placed thereon. And further wrap the wrap film on it in triple
After leaving for 24 hours under the condition of 0 ° C., the film was scratched with nails and the amount of the peeled coating film was visually evaluated. A: There is almost no peeling of the coating film. Δ: Peeling of the coating film was slightly large. ×: Many peeling of the coating film.

Adhesiveness A commercially available cellophane tape (width: 18 mm, length: 50) is formed on the surface (longitudinal direction) of the heat-sensitive recording layer of the heat-sensitive recording medium after the heat-sensitive recording layer is formed.
mm), the cellophane tape was strongly peeled off, and the amount of the heat-sensitive recording layer adhered to the cellophane tape was visually determined. A: There is almost no adhesion of the heat-sensitive recording layer to the cellophane tape. ：: The cellophane tape has a little adhesion of the heat-sensitive recording layer.

[0055]

[Table 1]

[0056]

As is clear from the results in Table 1, the adhesion of the anchor coat layer to the support and the heat-sensitive recording layer is excellent.
In addition, the anchor coat layer has an excellent swelling resistance to a plasticizer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Takushi Umemoto 4-3-1 Jokoji, Amagasaki City, Hyogo Prefecture Oji Paper Co., Ltd. Amagasaki Research Center F-term (reference) 2H026 AA07 BB02 BB21 CC00 DD19 DD48 EE05 FF01 FF15

Claims (4)

[Claims] 1. A thermosensitive recording medium having, on a support, an anchor coat layer containing a hydrophobic resin as a main component and a thermosensitive recording layer containing a leuco dye, a coloring agent and an adhesive in that order, a dioctyl phthalate ( A thermosensitive recording medium, wherein the degree of swelling of the anchor coat layer with respect to DOP) is 30% or less. 2. The heat-sensitive recording material according to claim 1, wherein the hydrophobic resin in the anchor coat layer is an emulsion-polymerized acrylic resin. 3. The support according to claim 1, wherein the support is a resin film.
Or the heat-sensitive recording material according to 2. 4. The heat-sensitive recording material according to claim 4, wherein the resin film is a polyethylene terephthalate film.