JP2007105963A - Thermal recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermal recording medium which is excellent in water resistance, printing suitability, sticking resistance, recording sensitivity, etc. has magnetic recording characteristics on the back side and can be used suitably in a wide range of fields. <P>SOLUTION: In the thermal recoding medium which has a thermal recording layer containing a leuco dye, a developer and an adhesive on one side of a substrate, the adhesive in the thermal recording layer contains a copolymer resin emulsion, and a copolymer resin constituting the copolymer resin emulsion (1) includes (i) (meth)acrylonitrile and (ii) a vinyl monomer copolymerizable with the (meth)acrylonitrile and (2) has a solubility parameter of 12.0 or above. The vinyl monomer (ii) includes at least one carboxyl group-containing vinyl monomer and the rate of the monomer is 1-10 mass% of the entire mass of the copolymer resin. The medium has a magnetic recording layer containing a magnetic substance compound and an adhesive on the other side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has a thermal recording layer containing a leuco dye, a colorant and an adhesive on one side of a support, and a magnetic recording layer containing a magnetic compound and an adhesive on the other side. The present invention relates to a thermal recording medium.

  2. Description of the Related Art A heat-sensitive recording material that uses a color-forming reaction of a colorless or light-colored leuco dye and an organic or inorganic colorant and makes both color developing substances contact with heat to obtain a recorded image is well known. Such a thermal recording medium is relatively inexpensive, has a compact recording device, and is easy to maintain, so that it is used as a recording medium in a wide range of fields including recording media for facsimiles and various computers.

One of the important qualities of such a heat-sensitive recording material is water resistance that can prevent the heat-sensitive recording layer from falling off when touched by water, and can suppress the fading of the recording portion due to water adhesion. In addition, when printing a thermal recording medium with a printer or the like, it is also required that sticking does not occur, that is, the sticking resistance is good.
In addition, recently, with the expansion of applications such as the use of thermal recording media for tickets, coupon tickets, commuter passes, etc., which have a magnetic recording layer on the back side, printability, for example, ink density (ink fillability), It is also demanded that ink density uniformity (printing smoothness) and the like are good.

As for the technology for imparting water resistance to the heat-sensitive recording layer, it is known to use a carboxy group-containing aqueous polymer and an oxazoline group-containing aqueous polymer as an adhesive component (see Patent Document 1). Further, it is obtained by polymerizing mainly at least one hydrophobic vinyl monomer having a glass transition temperature of 55 ° C. or more in the presence of a polymer latex having a glass transition temperature of 50 ° C. or less as a binder component of the thermosensitive recording layer. It is known to use a specific amount of a water dispersible polymer having a softening point of 150 to 260 ° C. (see Patent Document 2). In addition, it is known to use a water-soluble modified polyvinyl acetal resin having a specific hydrophilic group (see Patent Document 3). In addition, a polymer emulsion obtained by subjecting a monomer containing (meth) acrylonitrile, (meth) acrylic acid ester and ethylenically unsaturated carboxylic acid as an adhesive to emulsion polymerization under specific conditions in a heat-sensitive recording material. It is known to use (refer patent document 4). Further, it is known that 70% or more of the binder used in the heat-sensitive recording layer is an acrylate copolymer (see Patent Document 5). It is also known that the thermosensitive recording layer contains a copolymer of a vinyl monomer having a heterocyclic group with basic nitrogen in the ring and an ethylenic vinyl monomer having an α, β saturated double bond ( (See Patent Document 6). It is also known that the heat-sensitive recording layer contains an acrylic emulsion and colloidal silica, and further contains an inorganic pigment having a specific particle size (see Patent Document 7). However, with these techniques, sufficient water resistance and printability may not be obtained.

It is also known to use at least one crosslinking agent of a diol compound and an aldehyde compound in the heat-sensitive recording layer for the purpose of improving water resistance (see Patent Document 8). However, when a cross-linking agent is used, there are problems that it takes time for the cross-linking and the productivity of the thermal recording material is lowered.

It is also known to use a specific copolymer resin emulsion and a polyolefin copolymer resin emulsion for the protective layer in order to solve the problems derived from the crosslinking agent and at the same time improve the water resistance (see Patent Documents 9 and 10). . However, further improvement in characteristics such as recording sensitivity has been demanded.

It is also known to contain a composite of colloidal silica and an acrylic polymer or a styrene / acrylic polymer and an emulsified and dispersed stearamide in order to increase water resistance and sticking resistance. (See Patent Document 11). It is also known that a heat-sensitive recording layer contains a hydrophobic acrylic resin having an average molecular weight of 5 million or more and casein as an adhesive (see Patent Document 12). In order to improve water resistance and printability, it is also possible to use a silicon-modified polyvinyl alcohol and a water-soluble graft copolymer of silicon and a polymer containing an ethylenically unsaturated carboxylic acid as an adhesive. It is known (see Patent Document 13). These water resistance, sticking resistance, and printability are sufficiently satisfactory, but it is preferable to further improve if possible.

JP-A-6-155916 JP-A-6-206376 JP-A-6-344668 JP-A-8-337057 JP 2001-277719 A JP 2003-94806 A JP 2004-25775 A JP 2002-29155 A JP 2004-74531 A International Publication 2004/016440 JP-A-9-207435 Japanese Patent Laid-Open No. 10-272839 JP-A-11-227336

  An object of the present invention is to provide a heat-sensitive recording material that is excellent in water resistance, printability, sticking resistance, recording sensitivity, etc., and further has magnetic recording characteristics on the back surface and can be suitably used in a wide range of fields.

As a result of intensive studies aimed at solving the above problems, the present inventor has improved the water resistance and the like of the thermosensitive recording material by using a copolymer resin emulsion having specific properties in the thermosensitive recording layer. As a result, the present invention has been completed.
That is, the present invention relates to the following thermal recording material.
Item 1: In a thermosensitive recording medium having a thermosensitive recording layer containing a leuco dye, a colorant and an adhesive on one surface of the support,
The heat-sensitive recording layer contains a leuco dye, a colorant and a copolymer resin emulsion,
The copolymer resin constituting the copolymer emulsion is:
(1) comprising (i) (meth) acrylonitrile and (ii) a vinyl monomer copolymerizable with (meth) acrylonitrile, and
(2) The solubility parameter is 12.0 or more,
The vinyl monomer (ii) includes at least one carboxyl group-containing vinyl monomer,
A thermosensitive material having a magnetic recording layer in which the ratio of the carboxyl group-containing vinyl monomer is 1 to 10% by mass in the total mass of the copolymer resin and the other surface contains a magnetic compound and an adhesive. Recorded body.
Item 2: The heat-sensitive recording material according to Item 1, wherein the glass transition temperature of the copolymer resin constituting the copolymer resin emulsion is more than 30 ° C and not more than 100 ° C.
Preferably,
In a thermal recording body having a thermal recording layer containing a leuco dye, a colorant and an adhesive on one side of the support,
The heat-sensitive recording layer contains a leuco dye, a colorant and a copolymer resin emulsion,
The copolymer resin constituting the copolymer resin emulsion is:
(1) comprising a vinyl monomer copolymerizable with (i) (meth) acrylonitrile and (ii) (meth) acrylonitrile,
(2) the solubility parameter is 12.0 or more, and
(3) The glass transition temperature is higher than 30 ° C and not higher than 100 ° C,
The vinyl monomer (ii) includes at least one carboxyl group-containing vinyl monomer,
A thermosensitive material having a magnetic recording layer in which the ratio of the carboxyl group-containing vinyl monomer is 1 to 10% by mass in the total mass of the copolymer resin and the other surface contains a magnetic compound and an adhesive. Recorded body.
Item 3: The heat-sensitive recording material according to Item 1 or 2, wherein the amount of solid content after drying of the copolymer resin emulsion is 10 to 50% by mass with respect to the total solid content of the heat-sensitive recording layer.
Item 4: The heat-sensitive recording material according to any one of Items 1 to 3, wherein the heat-sensitive recording layer further contains polyvinyl alcohol having a polymerization degree of 1000 or more.
Item 5: The heat-sensitive recording material according to Item 4, wherein the polyvinyl alcohol is silicon-modified polyvinyl alcohol.
Item 6: The heat-sensitive recording material according to Item 4 or 5, wherein the amount of the polyvinyl alcohol is 1 to 10% by mass relative to the total solid content of the heat-sensitive recording layer.

According to the present invention, a heat-sensitive recording material having excellent water resistance, printability, sticking resistance, and scuff resistance, high productivity, excellent recording sensitivity, and magnetic recording characteristics on the back surface is obtained. Became possible.
The heat-sensitive recording material of the present invention has the above excellent properties without having a protective layer or using a crosslinking agent. That is, the heat-sensitive recording material of the present invention has excellent water resistance, printability, sticking resistance, and scuff resistance even when a protective layer is not used or a crosslinking agent is not used. Combines excellent recording sensitivity.
When the thermal recording material of the present invention does not have a protective layer, the coating process of the protective layer can be omitted, and when the cross-linking agent is not used, the time required for crosslinking and muro treatment can be eliminated. And high productivity.

Hereinafter, the present invention will be described in detail.
In the present specification and claims, the expression “(meth) acrylonitrile” means acrylonitrile and / or methacrylonitrile. The expression “(meth) acrylic acid ester” refers to acrylic acid ester and / or methacrylic acid ester such as methyl acrylate and / or methyl methacrylate.

-Copolymer resin emulsion The heat-sensitive recording layer in the heat-sensitive recording material of the present invention uses a copolymer resin emulsion having the following characteristics as a main adhesive:
(I) (meth) acrylonitrile and (ii) a vinyl monomer copolymerizable with (meth) acrylonitrile as copolymerization components;
The solubility parameter is 12.0 or higher;
The vinyl monomer copolymerizable with (meth) acrylonitrile in (ii) includes at least one carboxyl group-containing vinyl monomer;
The ratio of the carboxyl group-containing vinyl monomer is 1 to 10% by mass in the total mass of the copolymer resin.
By using a copolymer resin emulsion satisfying the above conditions as an adhesive for the heat-sensitive recording layer, sufficient quality as a heat-sensitive recording material can be obtained without forming a protective layer.
In particular, it has excellent water resistance, printability, sticking resistance, recording sensitivity, etc., and does not lose water when offset printing is performed. It is possible to obtain a heat-sensitive recording material in which the line part is affected and a clear image line part cannot be formed.

· Copolymer resin constituting the copolymer resin emulsion to be used in the component present invention copolymer resin, copolymerized (i) (meth) acrylonitrile and (ii) (meth) acrylonitrile can be copolymerized with vinyl monomer Contains as an ingredient.
(I) (Meth) acrylonitrile The proportion of (meth) acrylonitrile in the copolymer resin is not particularly limited as long as the effect of the present invention is achieved, but is preferably about 20 to 80% by mass, and Preferably it is about 30-70 mass%.
When the ratio of (meth) acrylonitrile is 20% by mass or more, sufficient water resistance is obtained, and the sticking resistance is not hindered. Moreover, if it is 80 mass% or less, there is no possibility that manufacturing (polymerization) stability of an emulsion may be inferior, and Tg of copolymer resin does not become higher than necessary. In addition, there is no possibility that the film forming property of the emulsion and the binding property to the filler will be hindered.
(Ii) Vinyl monomers copolymerizable with (meth) acrylonitrile Examples of vinyl monomers copolymerizable with (meth) acrylonitrile include:
Carboxyl group-containing vinyl monomer,
(Meth) acrylic acid methyl, (meth) acrylic acid ethyl, (meth) acrylic acid butyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid alkyl (meth) acrylate, (meth) acrylic acid 2-hydroxyethyl, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-aminoethyl (meth) acrylate, 2- (N-methylamino) ethyl (meth) acrylate, (Meth) acrylic acid esters such as 2- (N, N-dimethylamino) ethyl (meth) acrylate and glycidyl (meth) acrylate,
Vinyl esters such as vinyl acetate and vinyl propionate,
Aromatic vinyl monomers such as styrene, α-methylstyrene, divinylbenzene,
N-substituted unsaturated carboxylic acid amides such as (meth) acrylamide and N-methylol (meth) acrylamide,
Heterocyclic vinyl compounds such as vinylpyrrolidone,
Vinylidene halide compounds such as vinylidene chloride and vinylidene fluoride,
Α-olefins such as ethylene and propylene,
Examples thereof include one or a combination of two or more selected from the group consisting of dienes such as butadiene.
The ratio of the vinyl monomer copolymerizable with (meth) acrylonitrile in the copolymer resin is not particularly limited as long as the effect of the present invention is exhibited, but is preferably about 80 to 20% by mass, and more preferably. Is about 70 to 30% by mass.

If the ratio of the vinyl monomer copolymerizable with (meth) acrylonitrile is 20% by mass or more, there is no fear that the production (polymerization) stability of the emulsion is inferior, and the Tg of the copolymer resin does not become higher than necessary. In addition, there is no possibility that the film forming property of the emulsion and the binding property to the filler will be hindered. Moreover, if it is 80 mass% or less,
Sufficient water resistance is obtained, and sticking resistance is not hindered.

The vinyl monomer copolymerizable with (meth) acrylonitrile in the present invention contains at least one vinyl monomer containing one or more carboxyl groups.
Examples of carboxyl group-containing vinyl monomers include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, ethylenically unsaturated dicarboxylic acids such as itaconic acid, maleic acid, and fumaric acid, and monocarboxylic acids thereof. The 1 type, or 2 or more types of combination chosen from the group which consists of alkylesters is mentioned.

The carboxyl group-containing vinyl monomer in the copolymer resin of the present invention is essential for ensuring the polymerization stability of the copolymer resin when preparing the copolymer resin emulsion, and is neutralized with a base after polymerization. As a result, the resin particle surface layer is hydrated and softened, and the film-forming property of the copolymer resin emulsion is improved. It also has a function of enhancing the dispersibility and binding properties of various fillers added as necessary. Furthermore, the carboxyl group also acts as a reactive group with a crosslinking agent used in combination as necessary.
The ratio of the carboxyl group-containing vinyl monomer is preferably in the range of 1 to 10% by mass, more preferably 2 to 8% by mass, based on the total mass of the copolymer resin.
When the content is 1% by mass or more, the polymerization stability of the copolymer resin is not lost, the softening of the resin particles is good even during neutralization, and the film-forming property of the copolymer resin emulsion is excellent. If the content is 10% by mass or less, the heat-sensitive recording layer has sufficient water resistance, and further, there is no fear of gelation due to dissolution of resin particles during neutralization.

-Solubility parameter In this invention, the solubility parameter of the copolymer resin which comprises a copolymer resin emulsion shall be 12.0 or more. The solubility parameter is described in, for example, Iwanami Dictionary of Physical Chemistry, 4th edition.
When the solubility parameter is 12.0 or more, the heat resistance against heat received from the thermal head during use (adhesiveness to the thermal head) is improved, and the internal cohesive force of the resin can be increased.
If the solubility parameter is less than 12.0, the thermal sensitivity of the thermal recording layer increases due to insufficient internal cohesion of the resin, so that the thermal recording layer is easily softened and the running stability of the thermal head is lacking.
The upper limit of the solubility parameter is not particularly set, but in consideration of the characteristics of the copolymer resin used in the present invention and industrial production efficiency, a range of 14.0 or less is preferable.
When the solubility parameter is 14.0 or less, the hydrophilicity of the copolymer resin is increased, there is no fear that the water resistance is greatly reduced, and the production of the copolymer resin emulsion is facilitated.
The solubility parameter in the present invention is a value calculated from the molecular structure of each copolymer component, the total evaporation energy of atomic groups, and the molar volume ratio of the copolymer component.
The solubility parameter calculation method is described in Journal of Technology Coatings VOL. 55, No696, P.I. According to description of 100-101, it can calculate based on the following formula 1.
[delta] = _{[(ΣΔe i) (X) /} (ΣΔv i) (X) ] ^0.5 (Equation 1)
(Δ: solubility parameter, X: molar fraction of monomer used for copolymerization, Δe _i : evaporation energy of each monomer, Δv _i : molar volume)
A copolymer resin having a specific solubility parameter can be prepared by selecting a monomer to be a copolymer component and setting a blending ratio.

Other properties of copolymer resin emulsion The average primary particle diameter of the copolymer resin emulsion (number average particle diameter by dynamic light scattering method, measuring device: trade name: LPA3100, manufactured by Otsuka Electronics Co., Ltd.) is not particularly limited, but preferably Is about 50 to 500 nm, more preferably about 70 to 300 nm.
When the average particle size is 50 nm or more, the viscosity of the emulsion does not increase significantly. Therefore, it is not necessary to reduce the resin concentration at the time of manufacture, and the drying property of the thermal recording layer coating liquid is not slowed. Therefore, there is an economic advantage that the productivity of the thermal recording material is not hindered. On the other hand, when the thickness is 500 nm or less, the surface of the thermosensitive recording layer becomes dense, and a desired effect is easily exhibited.
Adjustment of the average particle diameter can be easily performed by knowledge of those skilled in the art. For example, the average particle diameter can be adjusted by appropriately selecting the composition of the raw material monomer of the copolymer resin emulsion and the type of the surfactant.

The glass transition temperature of the copolymer resin constituting the copolymer resin emulsion is preferably more than 30 ° C. and about 100 ° C. or less, and more preferably more than 30 ° C. and about 70 ° C. or less.
When the glass transition temperature exceeds 30 ° C., the heat resistance is excellent, and when it is 100 ° C. or lower, the problem of poor film formability does not occur, and as a result, water resistance, printability, and sticking resistance are improved.
In the present invention, since the solubility parameter regarding the copolymer resin emulsion as an adhesive is set to 12.0 or more, even if the glass transition temperature of the copolymer resin exceeds 30 ° C., the adhesiveness is not inferior. .
By setting the solubility parameter and the glass transition temperature for the copolymer resin emulsion contained in the heat-sensitive recording layer, a heat-sensitive recording material having excellent heat resistance, excellent water resistance, printability, and the like can be obtained.

-Method for producing copolymer resin emulsion The copolymer resin emulsion can be produced , for example, according to the method disclosed in International Publication No. 2004/016440.
In producing a copolymer resin emulsion, an emulsifier can be used as necessary to impart stability of the emulsion.
Examples of the emulsifier include anionic surfactants such as higher alcohol sulfates, alkylbenzene sulfonates, aliphatic sulfonates, alkyl diphenyl ether sulfonates, polyethylene glycol alkyl ester types, alkyl phenyl ether types, alkyl ethers. 1 type (s) or 2 or more types selected from the group which consists of nonionic surfactants, such as a type | mold, can be used.
The amount of the emulsifier used is not particularly limited, but is preferably the minimum amount in consideration of the water resistance of the resin.
In producing the copolymer resin emulsion, a polymerization initiator may be used as necessary.
Polymerization initiators include persulfates, hydrogen peroxide, organic hydroperoxides, water-soluble initiators such as azobiscyanovaleric acid, oil-soluble initiators such as azobisisobutyronitrile and benzoyl peroxide, or reducing agents. Is used in combination with a redox initiator. There is no restriction | limiting in particular about the usage-amount of a polymerization initiator, Although what is necessary is just to follow a well-known technique, Usually, 0.1-10 mass parts with respect to 100 mass parts of vinyl monomers, Preferably it is about 0.1-5 mass parts. It is.
Furthermore, when manufacturing a copolymer resin emulsion, you may use a molecular weight modifier (chain transfer agent) as needed. Examples of molecular weight regulators include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, low molecular halogen compounds, and the like.
The copolymer resin emulsion is prepared by neutralization with a base. Although the neutralizing agent in that case can be selected suitably, it is preferable to use aqueous ammonia. Aqueous ammonia can easily be detached at a relatively low temperature, so that the water resistance can be obtained in a short time after the heat-sensitive recording layer is formed.

-Amount of copolymer resin emulsion The amount of the copolymer resin emulsion is about 10 to 50% by mass, preferably about 10 to 30% by mass, based on the total solid content of the heat-sensitive recording layer, after drying. Is preferred.
When the content is 10% by mass or more, sufficient water resistance and printability can be obtained, and when the content is 50% by mass or less, the coloring component ratio decreases and the recording sensitivity does not deteriorate.

Polyvinyl alcohol having a degree of polymerization of 1000 or more In the present invention, the heat-sensitive recording layer preferably further contains polyvinyl alcohol having a degree of polymerization of 1000 or more.
By including polyvinyl alcohol with a polymerization degree of 1000 or more in the thermal recording layer, the thermal recording layer is not peeled off and adhered to the blanket by ink with strong tack strength during offset printing, further improving blanket contamination. Printability can be improved.
Even if other water-soluble adhesives are used, the same effect may be obtained, but polyvinyl alcohol has a great effect of improving printability.
In particular, when the degree of polymerization of polyvinyl alcohol is 1000 or more, particularly 1000 to 2500, the effect of improving the surface strength of the thermosensitive recording layer is great, and even a small amount can greatly improve blanket stains. In addition, there is no risk of reducing the water resistance of the surface of the heat-sensitive recording layer.
In addition, by using polyvinyl alcohol having a degree of polymerization of 1000 or more in combination with the copolymer resin emulsion in the heat-sensitive recording layer, the copolymer resin emulsion can be prevented from being separated from other materials.

Examples of the polyvinyl alcohol used include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol.
Of these, silicon-modified polyvinyl alcohol is preferred because it has a high effect of improving the water resistance of the heat-sensitive recording material.
As the silicon-modified polyvinyl alcohol, for example, those described in JP-A-58-79003 can be used.

The preferable content of polyvinyl alcohol having a polymerization degree of 1000 or more is about 1 to 10% by mass, preferably about 1 to 7% by mass, based on the total solid content of the heat-sensitive recording layer.
When the content exceeds 1% by mass, the surface strength of the thermosensitive recording layer is good, and when it is 10% by mass or less, there is no fear that the water resistance decreases.

In the heat-sensitive recording layer of the present invention, other water-soluble adhesives can be used as long as the effects of the invention are not impaired.
Examples of other adhesives include starches such as oxidized starch, esterified starch, and etherified starch, cellulose resins such as methyl cellulose, carboxymethyl cellulose, methoxy cellulose, and hydroxyethyl cellulose, styrene / maleic anhydride copolymers, and the like. Alkali salt, isobutylene / maleic anhydride copolymer, starch-vinyl acetate graft copolymer and its alkali salt, casein, gelatin, vinyl acetate resin latex, urethane resin latex, styrene / butadiene copolymer latex, acrylic resin System latex, polyvinyl alcohol other than the above, and the like.

Leuco dyes and colorants As the leuco dyes and colorants contained in the heat-sensitive recording layer of the present invention, various known ones can be used. Specific examples of the leuco dye include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl). ) -6-dimethylaminophthalide, blue coloring dyes such as 3-diethylamino-7-dibenzylamino-benzo [a] fluorane, 3- (N-ethyl-Np-tolyl) amino-7-N- Green coloring dyes such as methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino- Red coloring dyes such as 6-methyl-7-chlorofluorane and 3-diethylamino-6,8-dimethylfluorane; Ru-N-isopentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p- Dimethylanilino) fluorane, 3- (N-ethyl-Np-toluidino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-di ( N-butyl) amino-6-methyl-7-anilinofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o- Chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethy Amino-6-methylfluorane, 3-cyclohexylamino-6-chlorofluorane, 3- (N-ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluorane, 3-di (N -Pentyl) amino-6-methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-2-tetrahydro) Furfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (Nn-hexyl-N-ethylamino) -6-methyl- 7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropiyl) ) -N-methylamino] -6-methyl-7-anilinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7 -(P-Toluidino) fluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3- (4-dimethylamino) alinino-5 Black coloring dyes such as 7-dimethylfluorane, 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- - chloro fluoran, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '- (6'-dimethylamino) phthalide dyes having an absorption wavelength in the near infrared region of the like. Of course, it is not limited to these, Moreover, it is also possible to use 2 or more types together.

Specific examples of the colorant include, for example, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4′-dihydroxy-diphenylmethane, 4,4′-isopropylidenediphenol (bisphenol A), Hydroquinone, 4,4′-cyclohexylidenebisphenol, 4,4 ′-(1,3-dimethylbutylidene) bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methyl-pentane, 4,4 ′ -Dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 2,4- Bis (phenylsulfonyl) phenol, 2,2 ′-[4- (4-hydro Xylphenylsulfonyl) phenoxy] diethyl ether, 1,3,3-trimethyl-1- (p-hydroxyphenyl) -6-hydroxyindane, 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-iso Propoxydiphenylsulfone, 4-hydroxy-3 ′, 4′-trimethylenediphenylsulfone, 4-hydroxy-3 ′, 4′-tetramethylenediphenylsulfone, 3,4-dihydroxy-4′-methyldiphenylsulfone, bis (3 -Allyl-4-hydroxyphenyl) sulfone, 1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4-hydroxytolylbenzoate, p-hydroxy Ci-N- (2-phenoxyethyl) benzenesulfonamide, 1,8-bis (4-hydroxyphenylthio) -3,6-dioxa-octane, (4-hydroxyphenylthio) acetic acid-2- (4-hydroxy Phenylthio) ethyl ester, novolac type phenolic resin, phenolic compound such as phenol polymer, N- (p-tolylsulfonyl) carbamoyl acid-p-cumylphenyl ester, 4,4′-bis (Np-tolyl) Sulfonylaminocarbonylamino) diphenylmethane, 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylsulfone, Np-tolylsulfonyl-N′-p-butoxycarbonylphenylurea, Np-tolylsulfonyl -N'-phenylurea, Np-tolylsulfonyl-N'-3 (P- tolylsulfonyloxy) having a _-SO 2 NH- bond in the molecule, such as phenylurea, p- chlorobenzoic acid zinc, 4- [2-(p- methoxyphenoxy) ethyloxy] zinc salicylate, 4- [ Examples thereof include zinc salts of aromatic carboxylic acids such as zinc 3- (p-tolylsulfonyl) propyloxy] salicylate and zinc 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylate.
Of course, it is not limited to these, Moreover, it is also possible to use 2 or more types together.

The use ratio of the leuco dye and the colorant is appropriately selected according to the type of the leuco dye and the colorant to be used, and is not particularly limited, but is generally 100 with respect to 100 parts by mass of the leuco dye. A colorant of about 1000 parts by mass, preferably about 100 to 500 parts by mass is used.
The content of the leuco dye in the heat-sensitive recording layer is generally about 5 to 50% by mass, particularly about 8 to 30% by mass.
Further, the content of the colorant in the heat-sensitive recording layer is generally about 5 to 60% by mass, particularly about 10 to 50% by mass.

The other component thermosensitive recording layer may contain a storability improving agent for enhancing the storage stability of the recorded image and a sensitizer for enhancing the recording sensitivity.
Specific examples of such preservability improvers include, for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 4, 4′-butylidenebis (6-tert-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2 -Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) Hindered phenol compounds such as propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenylsulfone, 4-benzyl Examples thereof include epoxy compounds such as oxy-4 ′-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate, cresol novolac epoxy resin, phenol novolac epoxy resin, and bisphenol A epoxy resin. Of course, it is not limited to these, Moreover, it is also possible to use 2 or more types together.
The amount of the storage stability improver is not particularly limited, but is generally 1 to 40% by mass, particularly about 2 to 30% by mass with respect to the total solid content of the heat-sensitive recording layer.

Specific examples of the sensitizer include, for example, stearamide, methylenebisstearate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, p- Tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-chlorophenoxy) ) Ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetoluidide P-acetophenetide, N-acetoacetyl-p-toluidine, (Β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, oxalic acid Examples thereof include dibenzyl ester. Of course, it is not limited to these, Moreover, it is also possible to use 2 or more types together.
The amount of the sensitizer used is not particularly limited, but is generally about 3 to 40% by mass, particularly about 5 to 30% by mass with respect to the total solid content of the heat-sensitive recording layer.

In the heat-sensitive recording layer, if necessary, kaolin, calcium carbonate, amorphous silica, titanium oxide, aluminum hydroxide, calcined kaolin, zinc oxide and other pigments, zinc stearate, calcium stearate and other lubricants, and fluorescent dyes UV absorbers, surfactants, and the like can also be added.
The heat-sensitive recording layer of the present invention preferably does not contain a crosslinking agent.
The present invention is excellent in properties such as water resistance, printability, and sticking resistance, even if the heat-sensitive recording layer does not contain a crosslinking agent. Further, when no cross-linking agent is used, there is no need to worry about discoloration or yellowing of the heat-sensitive recording material, and the time required for cross-linking or long-time muro treatment is not required in the production process of the heat-sensitive recording material. High productivity can also be obtained.

Method for producing heat-sensitive recording layer The heat-sensitive recording layer generally comprises water as a dispersion medium, and a leuco dye, a colorant, a sensitizer and, if necessary, a storability improver, or separately, separately or separately. The mixture is finely dispersed with an appropriate dispersant so that the average particle size is 2 μm or less by a stirring / pulverizing machine such as a sand mill, and then the copolymer resin emulsion having a solubility parameter of 12 or more is added if necessary. The application amount after drying the heat-sensitive recording layer coating solution prepared by adding other adhesives on the support is about 1 to 15 g / m ² , particularly about ² to 10 g / m ^2. It is formed by coating and drying.
The method for applying the thermal recording layer coating liquid is not particularly limited, and conventionally known methods such as air knife coating, varibar blade coating, pure blade coating, gravure coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. Any of these coating methods can be employed.

Undercoat layer In the present invention, an undercoat layer may be provided between the support and the heat-sensitive recording layer, if necessary, in order to further improve the recording sensitivity and the recording runnability.
The undercoat layer has an oil absorption amount of 70 ml / 100 g or more, particularly at least one selected from the group consisting of an oil-absorbing pigment, organic hollow particles, and thermally expandable particles having a viscosity of about 80 to 150 ml / 100 g, and an adhesive as a main component. The undercoat layer coating solution is applied and dried on a support. Here, the oil absorption is a value determined according to the method of JIS K 5101-1991.

As the oil-absorbing pigment, various pigments can be used. Specific examples include inorganic pigments such as calcined kaolin, amorphous silica, light calcium carbonate, and talc. The average particle diameter of these oil-absorbing pigments (50% value by laser diffraction type particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation)) is about 0.01 to 5 μm, particularly about 0.02 to 3 μm. Is preferred.
The amount of the oil-absorbing pigment can be selected from a wide range, but it is generally preferably about 50 to 95% by mass, particularly about 70 to 90% by mass, based on the total solid content of the undercoat layer.

Moreover, as an organic hollow particle, a conventionally well-known thing, for example, the particle | grains whose hollow rate consists of an acrylic resin, a styrene resin, a vinylidene chloride resin etc. about 50-99% can be illustrated. Here, the hollowness is a value obtained by (d / D) × 100. In the formula, d represents the inner diameter of the organic hollow particles, and D represents the outer diameter of the organic hollow particles. The average particle diameter of the organic hollow particles (50% value by a laser diffraction particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation)) is preferably about 0.5 to 10 μm, particularly preferably about 1 to 3 μm.
The amount of the organic hollow particles used can be selected from a wide range, but is generally 20 to 90% by mass, particularly preferably about 30 to 70% by mass, based on the total solid content of the undercoat layer.

  When the oil-absorbing inorganic pigment is used in combination with the organic hollow particles, the oil-absorbing inorganic pigment and the organic hollow particles are used within the above-mentioned usage amount range, and the total amount of the oil-absorbing inorganic pigment and the organic hollow particles is the entire undercoat layer. It is preferable that it is 40-90 mass% with respect to solid content, especially about 50-80 mass%.

Various types of thermally expandable particles can be used. Specific examples include thermally expandable fine particles obtained by microencapsulating low-boiling hydrocarbons with a copolymer such as vinylidene chloride and acrylonitrile by an in situ polymerization method. Is given. Examples of the low boiling point hydrocarbon include ethane and propane.
The amount of the thermally expandable particles can be selected from a wide range, but is generally about 1 to 80% by mass, particularly preferably about 10 to 70% by mass, based on the total solid content of the undercoat layer.

As the adhesive, an adhesive used for the heat-sensitive recording layer can be appropriately used, and starch-vinyl acetate graft copolymer, various polyvinyl alcohols, and styrene / butadiene copolymer latex are particularly preferable.
Examples of the various polyvinyl alcohols include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol.
The proportion of the adhesive used can be selected within a wide range, but generally it is preferably about 5 to 30% by mass, particularly preferably about 10 to 25% by mass, based on the total solid content of the undercoat layer.

The coating amount of the undercoat layer is about 3 to 20 g / ^{m 2} by dry weight, preferably to the 5~12g / ^{m 2} approximately.

The method for applying the coating solution for the undercoat layer is not particularly limited. For example, conventional methods such as air knife coating, varibar blade coating, pure blade coating, gravure coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. Any known coating method can be employed.

Protective layer In the present invention, a protective layer containing a film-forming adhesive as a main component can be provided on the heat-sensitive recording layer as long as the effect of the present invention is not impaired.
Examples of such adhesives include starches such as oxidized starch, esterified starch, and etherified starch, cellulose resins such as methylcellulose, carboxymethylcellulose, methoxycellulose, and hydroxyethylcellulose, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, Polyvinyl alcohols such as carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, styrene / maleic anhydride copolymer and its alkali salt, isobutylene / maleic anhydride copolymer and its alkali Salt, casein, gelatin, vinyl acetate resin latex, urethane resin latex, styrene / butadiene copolymer latex, Acrylic resin latex.

The protective layer is generally prepared by applying and drying a protective layer coating liquid obtained by mixing and stirring the above-mentioned adhesive, and optionally added pigments and various auxiliary agents on the heat-sensitive recording layer, using water as a medium. Can be obtained.
Examples of the pigment include inorganic pigments such as calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, and calcined kaolin, nylon resin filler, urea / formalin resin Examples thereof include organic pigments such as fillers and raw starch particles.
Although content of a pigment is not specifically limited, Preferably, it is about 5-80 mass% with respect to the total solid amount of a protective layer, More preferably, it is about 10-60 mass%.

As an auxiliary agent, for example, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax and other lubricants, alkylbenzene sulfonate sodium, dioctyl sulfosuccinate sodium, sulfone-modified polyvinyl alcohol, polyacrylic acid sodium and the like surface activity Agents, glyoxal, boric acid, dialdehyde starch, methylol urea, epoxy compounds, hydrazine compounds and other water resistance agents (crosslinking agents), UV absorbers, fluorescent dyes, coloring dyes, mold release agents, antioxidants, etc. Can be mentioned. The usage-amount of auxiliary agent can be suitably set from a wide range.
The method for applying the protective layer coating liquid is not particularly limited, and for example, known means such as air knife coating, varibar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. may be used. it can.
The coating amount of the protective coating liquid for, 0.5 to 3 g / ^{m 2} approximately by dry weight, preferably 0.8~2g / ^{m 2} approximately.

Magnetic recording layer The magnetic recording layer is made of a ferromagnetic powder made of polyurethane, vinyl acetate, vinyl chloride, polyacryl, styrene butadiene, or other water-soluble, water-dispersible aqueous binder, polyethylene oxide. It is obtained by coating or printing on a support such as paper, a magnetic paint uniformly dispersed with carboxymethylcellulose, metal stearate, wax, and other additives. As the polyvinyl alcohol-based dispersant for dispersing the stearic acid metal salt, cation-modified or anion-modified polyvinyl alcohol derivatives are used in addition to polyvinyl alcohol having various saponification degrees. As the ferromagnetic powder, γ ferrite, strontium ferrite, cobalt-containing ferrite, etc. are used. However, since magnetic recording information is not erased by ordinary magnets, barium ferrite and strontium ferrite having a coercive force of 1500 to 5000 oersted are often used. Is done. A polyacrylic acid salt or the like can be used for dispersing the magnetic powder. As the wax, paraffin wax, polyethylene wax, higher fatty acid alcohol, and higher fatty acid amide are used.

The coating amount of the magnetic recording layer coating solution is about 15 to 35 g / m ² in terms of dry weight.

Thermal recording material The thermal recording material of the present invention is obtained by applying and drying a thermal recording layer coating solution on one side of a support, and further applying and drying a magnetic recording layer coating solution on the other side. can get. If desired, the protective layer coating solution may be formed on the heat-sensitive recording layer in sequence by a method such as coating and drying.
The support is appropriately selected from paper (neutral paper, acid paper), plastic film, synthetic paper, non-woven fabric, metal deposit, and the like.
When producing a thermosensitive recording medium having an undercoat layer, the undercoat layer coating solution is applied to a support and dried to form an undercoat layer, and the thermal recording layer is sequentially provided on the obtained undercoat layer. Just do it.
The heat-sensitive recording material of the present invention has excellent water resistance, printability, sticking resistance, and rubbing stain resistance, and further has excellent recording sensitivity.

In particular, the heat-sensitive recording material of the present invention preferably has no protective layer.
By not providing a protective layer, it is possible to obtain a heat-sensitive recording material having high productivity and excellent recording sensitivity.
In general, the protective layer is provided for the purpose of improving water resistance, sticking resistance, printability, rubbing stain resistance, etc., but the thermal recording material of the present invention does not have a protective layer, and those characteristics are also provided. Is excellent.
In the present invention, various known techniques in the heat-sensitive recording material manufacturing field, such as applying a smoothing process such as supercalendering after various layers are formed or after all layers are formed, are required. It can be added. Furthermore, the heat-sensitive recording layer in the heat-sensitive recording material can be configured to be capable of multicolor recording.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.
In addition, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.
The solubility parameters in the examples were calculated using Journal of Technology Coatings VOL. 55, No696, P.I. It carried out based on the following formula 2 according to description of 100-101.
δ = [(ΣΔe _i ) (X) / (ΣΔv _i ) (X)] ^0.5 (Formula 2)
(Δ: solubility parameter, X: molar fraction of monomer used for copolymerization, Δe _i : evaporation energy of each monomer, Δv _i : molar volume)
The glass transition temperature of the copolymer resin film obtained by applying a copolymer resin emulsion on an aluminum foil and drying (drying at 60 ° C. for 5 hours) so that the thickness after drying is about 50 μm. The glass transition temperature was determined by measuring with a differential thermal analyzer (manufactured by Seiko Denshi Kogyo).

Example 1
-Preparation of coating solution for magnetic recording layer Barium ferrite (trade name: MC127, manufactured by Toda Kogyo Co., Ltd.) 100 parts (solid), urethane-acrylic resin 30 parts (solid), polyethylene oxide (manufactured by Sumitomo Seika Co., Ltd., weight average) A magnetic recording layer was prepared by dispersing a composition consisting of 5 parts (molecular weight 300,000) (solid), 10 parts (solid) of zinc stearate (polyvinyl alcohol dispersion, average particle size 0.9 μm), and 200 parts of water with a ball mill all day and night. A coating solution was obtained.

・ Preparation of liquid A (leuco dye dispersion)
A composition comprising 20 parts of 3-di (N-butyl) amino-6-methyl-7-anilinofluorane, 5 parts of a 5% aqueous solution of methylcellulose and 15 parts of water is averaged to 1.0 μm in a sand mill. Until crushed.

-Preparation of B liquid (colorant dispersion)
A composition comprising 20 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 5 parts of a 5% aqueous solution of methylcellulose and 15 parts of water was pulverized with a sand mill until the average particle size was 1.0 μm.

-Preparation of coating solution for heat-sensitive recording layer 60 parts of kaolin (trade name: UW-90, manufactured by EC), 60 parts dispersion, 20 parts A, 50 parts B, aqueous dispersion of zinc stearate (trade name) : Hydrin Z-8-36, solid content 36%, manufactured by Chukyo Yushi Co., Ltd.) 5 parts, paraffin wax (trade name: Hydrin E-139, solid content 30%, manufactured by Chukyo Yushi Co., Ltd.) 16 parts, copolymer resin (co-polymer) Polymerization component: (meth) acrylonitrile / (meth) alkyl acrylate / (meth) acrylic acid 2-hydroxyethyl / (meth) acrylic acid / (meth) acrylamide, ratio of (meth) acrylic acid: to the total mass of the copolymer resin 5 parts by weight, solubility parameter: 12.8, glass transition temperature: 50 ° C., average particle size: 230 nm) 60 parts emulsion (trade name: OT1043Z-1, concentration 25%, Mitsui Chemicals) A composition comprising 40 parts of a 10% aqueous solution of fully saponified polyvinyl alcohol (trade name: PVA117, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) was mixed and stirred to obtain a thermal recording coating solution.

· On one side of the creation basis weight 160 g / m ² paper heat-sensitive recording material, coated so as to 30 g / m ² the magnetic recording layer coating composition on a solids were dried magnetic field orientation. Subsequently, the thermal recording layer was applied to the other surface so that the coating amount after drying was 5 g / m ² to form a thermal recording layer, and then a super calender treatment was performed to obtain a thermal recording body. .

Example 2
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, silicon-modified polyvinyl alcohol (trade name: R-1130, polymerization degree) was used instead of completely saponified polyvinyl alcohol (trade name: PVA117, polymerization degree 1700, manufactured by Kuraray Co., Ltd.). 1700, manufactured by Kuraray Co., Ltd.) was used in the same manner as in Example 1 except that 40 parts of a 10% aqueous solution was used.

Example 3
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, instead of completely saponified polyvinyl alcohol (trade name: PVA117, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) (trade name: PVA105, polymerization degree 500, manufactured by Kuraray Co., Ltd.) A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 40 parts of a 20% aqueous solution was used.

Example 4
・ Preparation of coating solution for undercoat layer Calcined kaolin (trade name: Ancilex, manufactured by EC, oil absorption 90 ml / 100 g, average particle size: 0.6 μm) 30% dispersion 60 parts, fully saponified polyvinyl alcohol (product) Name: PVA117, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) 10% aqueous solution 10 parts, SBR latex (trade name: L-1571, concentration 48%, manufactured by Asahi Kasei Co., Ltd.) 10 parts mixed and stirred for undercoating A layer coating solution was obtained.

- in the creation of heat-sensitive recording material prepared in Example 2 of the heat-sensitive recording material, the undercoat layer coating liquid, between the support and the thermosensitive recording layer, as the coating amount after drying of 10 g / m ² A heat-sensitive recording material was obtained in the same manner as in Example 2 except that an undercoat layer was provided by coating and drying.

Comparative Example 1
In the preparation of the thermal recording layer coating liquid of Example 1, a styrene-butadiene latex (trade name: L-1571, concentration 48%, solubility) instead of the copolymer resin emulsion (trade name: OT1043Z-1, supra). A thermosensitive recording material was obtained in the same manner as in Example 1 except that 40 parts of parameter: 8.4, manufactured by Asahi Kasei Co., Ltd. were used.

Comparative Example 2
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, a copolymer resin emulsion (trade name: AM2250, which has a solubility parameter of 10.56) instead of the copolymer resin emulsion (trade name: OT1043Z-1, supra). A thermosensitive recording material was obtained in the same manner as in Example 1 except that 38 parts of a concentration of 52%, manufactured by Showa Polymer Co., Ltd. were used.

Comparative Example 3
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, a copolymer resin emulsion (trade name: OT1043Z-1, supra) was not used, and an aqueous solution of completely saponified polyvinyl alcohol (trade name: PVA117, supra) was used. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 240 parts were used.

Evaluation The following physical properties were measured for the heat-sensitive recording material thus obtained, and the results are shown in Table 1.

1. Water resistance The thermal recording material was immersed in water for 5 seconds, then pulled up, and immediately, the surface of the thermal recording layer was rubbed 10 times with a finger to evaluate the surface condition.
○: No change at all.
○ ': Although the surface was slightly changed, it is a level with no practical problem.
X: The heat-sensitive recording layer is largely removed.

2. Printability Using an offset printer (model name: MVF-18B, manufactured by Miyakoshi Co., Ltd.) and using four colors of ink (T & K RNC process manufactured by TOKA), 100 m / min. The printing suitability was evaluated based on the transferred ink density (ink fillability) and the uniformity of the ink density (printing smoothness) when printing was performed for 10 minutes at the above speed.
○: Printability is particularly excellent.
○ ': Printability is excellent.
X: Printability is inferior.

3. Scratch resistance and stain resistance The surface of the heat-sensitive recording layer of the heat-sensitive recording material was scratched with a spoon (tight plate type, manufactured by SUS410) to evaluate the degree of color development. Color development occurs due to the heat of scratching, but if there is resistance to scratching (rubbing), heat generation is small and color development does not occur.
○: No color development at all.
○ ': Color is slightly developed, but there is no practical problem.
(Triangle | delta): It is a level which color develops and becomes a problem practically.
X: Color development is severe

4). Recording density Using a thermal evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), printing was performed on the surface of the thermal recording layer of each thermal recording body at an applied voltage of 25 V and an applied energy of 0.24 mj / dot. The measurement was performed in the visual mode of a Macbeth densitometer (RD-914, manufactured by Macbeth).

5. Sticking resistance Using a thermal evaluation machine (trade name: FR410 TASSHA, manufactured by SATO), a test pattern is recorded on a thermal recording medium at an energy level of A3, 4 inches / second, and the degree of sticking generated is printed and Judgment was made on the printed surface.
A: There is almost no printing sound due to sticking, and there is no effect on the printing surface.
○: Print sound due to sticking is slightly recognized, but there is no effect on the print surface.
(Triangle | delta): The printing sound by sticking is loud, and a white streak is slightly seen also on the printing surface.
X: Print sound due to sticking is intense, and white streaks occur frequently on the print surface.

6). Yellowing The heat-sensitive recording material was allowed to stand for 1 month at 40 ° C. and 50% RH, and the surface condition was observed.
○: The original state is maintained.
(Triangle | delta): Although it has changed a little from the original state, it is a level which is satisfactory practically.
X: Large change.

Claims (6)

In the heat-sensitive recording material having a heat-sensitive recording layer containing a leuco dye, a colorant and an adhesive on one surface of the support, the adhesive in the heat-sensitive recording layer contains a copolymer resin emulsion. The copolymer resin constituting the polymer resin emulsion is
(1) comprising (i) (meth) acrylonitrile and (ii) a vinyl monomer copolymerizable with (meth) acrylonitrile, and
(2) The solubility parameter is 12.0 or more,
The vinyl monomer (ii) contains at least one carboxyl group-containing vinyl monomer, and the proportion of the carboxyl group-containing vinyl monomer is 1 to 10 mass in the total mass of the copolymer resin. %, And the other surface has a magnetic recording layer containing a magnetic compound and an adhesive. The heat-sensitive recording material according to claim 1, wherein the glass transition temperature of the copolymer resin constituting the copolymer resin emulsion is more than 30 ° C and not more than 100 ° C. The heat-sensitive recording material according to claim 1 or 2, wherein an amount of solid content after drying of the copolymer resin emulsion is 10 to 50% by mass with respect to the total solid content of the heat-sensitive recording layer. The thermosensitive recording material according to any one of claims 1 to 3, wherein the thermosensitive recording layer further contains polyvinyl alcohol having a degree of polymerization of 1000 or more. The heat-sensitive recording material according to claim 4, wherein the polyvinyl alcohol is silicon-modified polyvinyl alcohol. The heat-sensitive recording material according to claim 4 or 5, wherein the amount of the polyvinyl alcohol is 1 to 10% by mass relative to the total solid content of the heat-sensitive recording layer.