JPH06247048A - Heat sensitive recording body - Google Patents

Abstract

PURPOSE:To provide a heat sensitive recording body which is superior in 4water resistance, printability and also running properties at the time of recording. CONSTITUTION:In a heat sensitive recording body provided with a heat sensitive recording layer containing colorless or light-colored basic dyes, a coloration agent and further a protective layer, at least a water-soluble graft copolymer between a polymer containing unsaturated carboxylic acid and silicone is incorporated into the heat sensitive recording layer and protective layer.

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 which is excellent in water resistance and printability as well as running property during recording.

[0002]

2. Description of the Related Art A thermosensitive recording medium which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic color-forming agent to bring both color-forming substances into contact with each other by heat to obtain a color-developed image is often used. Are known. Since such a thermal recording medium is relatively inexpensive and the recording device is compact and its maintenance is relatively easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

As one of the fields of use thereof, a recording medium for a handy terminal is drawing attention. Such a handy terminal is often used outdoors, and the problem is that the recording surface gets wet and peels off in the case of rain. In addition, for use in a handy terminal or the like, there is an increasing demand for a heat-sensitive recording material having excellent printability in order to perform offset printing on the recording surface.

Conventionally, for the purpose of improving the water resistance of the heat-sensitive recording layer, JP-A-49-36343 and JP-A-54-133352 disclose methods of adding a water-proofing agent to the heat-sensitive recording layer, and JPA
Nos. 57-14998, 57-18520, and JP 2-8084 describe a method of using a hydrophobic polymer emulsion as an adhesive in a heat-sensitive recording layer, but still sufficient water resistance. However, at present, a recording layer excellent in printability and running property has not been obtained.

In addition, a protective layer containing a water-soluble polymer compound is heat-sensitively recorded for the purpose of solving the problem that the color-recorded image disappears when exposed to moisture, fingerprints, hand cream, or plastic such as vinyl chloride resin. Proposed on layers. When such a protective layer is provided, it is possible to prevent the color-recorded image from being erased, and it is possible to obtain the effect of improving problems such as sticking, head shavings, and rubbing stains.
There was a drawback that the water resistance and printability were extremely poor.

[0006]

The present invention solves each of the problems described above, and in particular, is water resistant (for example, has sufficient strength so that the surface of the thermosensitive recording medium does not peel off even when wet). And a heat-sensitive recording material which is excellent in printability (for example, a part of the surface of the recording material is not peeled off by printing) and is excellent in running property during recording.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium comprising a support and a thermosensitive recording layer containing a colorless or light-colored basic dye and a coloring agent and a protective layer. A heat-sensitive recording material, characterized in that a water-soluble graft copolymer of a polymer containing at least an ethylenically unsaturated carboxylic acid and a silicone is contained in the layer and the protective layer.

[0008]

The present invention is characterized in that the heat-sensitive recording layer and the protective layer contain a water-soluble graft copolymer of at least a polymer containing an ethylenically unsaturated carboxylic acid as a backbone polymer and a silicone. As specific examples of the polymer containing an ethylenically unsaturated carboxylic acid, for example, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polycrotonic acid, polyfumaric acid, polymaleic acid and the like, and a copolymer having the above-mentioned monomer component Examples thereof include a copolymer of acrylic acid and methyl methacrylate, a copolymer of maleic acid and styrene, and the like. Examples of silicones include dialkyl polysiloxanes such as dimethyl polysiloxane and diethyl polysiloxane, and diphenyl polysiloxane compounds.

The preferred ratio of silicone to the polymer containing ethylenically unsaturated carboxylic acid is in the range of 5 to 50% by weight, more preferably 10 to 30% by weight. Further, if the proportion of silicone is less than 5% by weight, the water resistance of the recording layer may not be obtained, and if it exceeds 50% by weight, the adhesive strength may decrease. In the present invention, the water-soluble graft copolymer of a polymer containing an ethylenically unsaturated carboxylic acid and silicone is preferably used as a salt of sodium, potassium, ammonium or the like.

The above water-soluble graft copolymer is, for example, a macromonomer having a (meth) acryloyl group at one end of a radical copolymerization component silicone, an ethylenically unsaturated carboxylic acid, and if necessary, another radically polymerizable monomer. It can be produced by reacting a graft copolymer obtained by copolymerizing a monomer with a base to form a salt.

As the ethylenically unsaturated carboxylic acid, those exemplified above can be used. Other radically polymerizable monomers include methyl acrylate, ethyl methacrylate, in addition to the above methyl methacrylate and styrene.
Examples thereof include alkyl (meth) acrylates such as ethyl acrylate and 2-ethylhexyl (meth) acrylate, and hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate.

The amount of the above specific water-soluble graft copolymer to be added to the heat-sensitive recording layer is not particularly limited, but it is preferably blended in an amount of about 1 to 15% by weight of the solid content forming the heat-sensitive recording layer. If the amount is too small, a sufficient effect of improving the water resistance may not be obtained, and if the amount is too large, the amount of the color forming component may decrease, and as a result, the color forming sensitivity may decrease.

When a protective layer is provided on the heat-sensitive recording layer, sticking and head residue can be improved and the storage stability of recording can be improved as described above. If sticking is poor, the recorded image will be affected, and if the print length becomes shorter than it should be, or if solid black recording is performed, the unprinted part will be a white line at right angles to the paper feed direction. In some cases, there is a problem such as the occurrence of problems.

In the present invention, the protective layer contains a water-soluble graft copolymer of the above-mentioned polymer containing an ethylenically unsaturated carboxylic acid and silicone. Further, a water-soluble binder, a latex, a pigment, etc. described later can be added to the protective layer. In the present invention, by incorporating the specific water-soluble graft copolymer in the protective layer, it is possible to obtain a heat-sensitive recording material which is extremely excellent in running property during recording, water resistance and printability.

The amount of the water-soluble graft copolymer of the above-mentioned ethylenically unsaturated carboxylic acid-containing polymer and silicone to be added to the protective layer is not particularly limited, but it is usually 5 with respect to the total solid content of the protective layer. It is preferable to add about 50% by weight. If it is too small, a sufficient effect of improving the water resistance may not be obtained, and if it is too large, the writability and imprintability may be slightly deteriorated.

In the heat-sensitive recording layer or the protective layer, in addition to a water-soluble graft copolymer of a polymer containing an ethylenically unsaturated carboxylic acid and silicone, as a binder, water resistance and printability are not impaired. For example, starches such as oxidized starch, enzyme-modified starch, cation-modified starch, esterified starch, etherified starch, cellulose derivatives such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, methoxy cellulose, hydroxyethyl cellulose, completely (or incompletely) saponified polyvinyl alcohol. Polyvinyl alcohol such as carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, sodium polyacrylate, polyacrylamide, polyvinylpyrrolidone, acrylic acid amide Acrylic acid ester copolymer,
Acrylic amide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, water-soluble polymer such as sodium alginate, gelatin, and casein; poly Vinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, polybutyl methacrylate, styrene / butadiene copolymer, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer, styrene / butadiene / acrylic copolymer It is possible to use a combination of latex and the like in combination.

In the present invention, the binder of the heat-sensitive recording layer has already been described, and the other components of the heat-sensitive recording layer will be described below. Various types of basic dyes that are colorless or light-colored are known, and examples thereof include the following. 3,3-bis (p-dimethylaminophenyl)
-6-Dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [ a] Fluoran, 3- (N-ethyl-N-p-tolyl) amino-
7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7
-Dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Diethylamino-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3 -(N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-
7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-
Pentyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) amino-7-
(O-Chlorophenylamino) fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl) -P
-Toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- (N-ethyl-N-flu) Furylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-
Anilinofluorane, 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluorane,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-Dimethylaminophenyl) ethylene-2-yl]
-4,5,6,7-Tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6 , 7
-Tetrachlorophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrabromophthalide, 3-p- (p
-Anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'- Xanthene-2′-ylamino] phenyl} propane, 3,6, -bis (dimethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide and the like can be mentioned. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Various compounds are known as colorants (acidic substances) used in combination with basic dyes, and the following are exemplified. Inorganic acidic substances such as activated clay, attapulgite, colloidal silica, aluminum silicate, 4-
Cumylphenol, hydroquinone monobenzyl ether, 4,4'-isopropylidenediphenol, 1,1
-Bis (4-hydroxyphenyl) cyclohexane,
4,4'-dihydroxydiphenyl-2,2-butane,
4,4'-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane,
2,2-bis (4-hydroxyphenyl) heptane, bis (4-hydroxyphenylthioethoxy) methane,
1,5-di (4-hydroxyphenylthio) -3-oxapentane, 1,1-bis (4-hydroxyphenyl)
-1-phenylethane, 1,4-bis [α-methyl-α
-(4'-hydroxyphenyl) ethyl] benzene,
1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 4,4′-dihydroxydiphenyl sulfide, bis (4-hydroxy-3-methylphenyl) sulfide, 4,4′- Dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4 -Hydroxyphenyl-4'-benzyloxyphenyl sulfone, 4-hydroxy-3 ',
4'-tetramethylene biphenyl sulfone, 3,4-dihydroxyphenyl-p-tolyl sulfone, 4-hydroxybenzoic acid benzyl ester, bis (p-hydroxyphenyl) acetate butyl, bis (p-hydroxyphenyl) acetate methyl, (4 -Hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester, di (p-hydroxyphenylthioethyl) ether, N, N'-di-m-chlorophenylthiourea, N-
Phenolic compounds such as (phenoxyethyl) -4-hydroxyphenylsulfonamide, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4-
Aromatic carboxylic acids such as {3- (p-tolylsulfonyl) propyloxy] salicylic acid, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, p-chlorobenzoic acid, and these aromatic carboxylic acids. Examples thereof include salts with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel, and organic acid substances such as antipyrine complex of zinc thiocyanate.

In the present invention, the use ratio of the color former and the color former in the recording layer should be appropriately selected according to the types of the color former and the color former to be used, and it is not particularly limited, but it is a basic dye. About 1 to 50 parts by weight, preferably about 2 to 10 parts by weight, of the coloring agent is used with respect to 1 part by weight.

The preparation of the coating liquid containing these substances is generally carried out by using water as a dispersion medium, stirring with a ball mill, attritor, sand mill or the like, and dispersing the color former and the color former together or separately by a pulverizer. And prepared as a coating liquid.
Further, various auxiliary agents can be added to the coating liquid as needed, and examples thereof include sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, dispersants such as fatty acid metal salts, and stearic acid. Zinc, calcium stearate,
Waxes such as polyethylene wax, carnauba wax, paraffin wax and ester wax, defoaming agents, fluorescent dyes, coloring dyes and the like are appropriately added.

It is also possible to use various pigments in combination in the coating liquid, for example, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth,
Inorganic pigments such as fine particulate anhydrous silica and activated clay, and organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, raw starch particles, polystyrene filler and the like can be mentioned.

Further, a sensitizer may be used in combination depending on the purpose. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, and methylenebisstearic acid. Amide, N-
Methylol stearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate,
Benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p- Chlorobenzyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane,
1,2-di (4-methylphenoxy) ethane, 1,2-
Di (4-methoxyphenoxy) ethane, 1,2-di (4
-Chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p
-Acetotoluidide, p-acetophenetidide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like are exemplified. To be done. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of about 4 parts by weight or less relative to 1 part by weight of the color developing agent.

Further, a preservative improving agent may be used in combination for the purpose of further enhancing preservability of a recorded image as long as the effect is not impaired. Specific examples of such a storage stability improver include, for example, 2,2'-methylenebis (4-methyl-6).
-Tert-butylphenol), 2,2'-ethylenebis (4-methyl-6-tert-butylphenol) 2,2 '
-Methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4,6-di-tert-
Butylphenol), 2,2'-ethylidene bis (4,
6-di-tert-butylphenol), 2,2'-ethylidenebis (4-methyl-6-tert-butylphenol), 2,2'-ethylidenebis (4-ethyl-6-te)
rt-Butylphenol), 2,2 '-(2,2-propylidene) bis (4,6-di-tert-butylphenol), 2,2'-methylenebis (4-methoxy-6-te)
rt-butylphenol), 2,2'-methylenebis (6
-Tert-butylphenol), 4,4'-thiobis (3
-Methyl-6-tert-butylphenol), 4,4'-
Thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (5-methyl-6-tert-butylphenol), 4,4'-thiobis (2-chloro-)
6-tert-butylphenol), 4,4'-thiobis (2-methoxy-6-tert-butylphenol), 4,
4'-thiobis (2-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 1- [α-methyl-α- (4'-
Hydroxyphenyl) ethyl] -4- [α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene,
1,1,3-tris (2-methyl-4-hydroxy-5)
-Cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy -3, 3 ', 5,
5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5
-Dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,
Hindered phenol compounds such as 2-bis (4-hydroxy-3,5-dimethylphenyl) propane, N,
N'-di-2-naphthyl-p-phenylenediamine,
Ethyleneimine compounds such as 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, 4,4'-bis (ethyleneiminecarbonylamino) diphenylmethane, 1,4-diglycidyloxybenzene ,
4,4'-diglycidyloxydiphenyl sulfone,
Epoxy compounds such as terephthalic acid diglycidyl ether, 4-benzyloxyphenyl-4 ′-(2-methyl-2,3-epoxypropyloxy) phenyl sulfone, and novolac type resin can be used.

Next, since the resin (binder) in the components of the protective layer has already been described, other components to be contained in the protective layer as necessary will be described below. In order to further improve printability and sticking, a pigment may be added to the protective layer, if necessary. Specific examples thereof include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide and silicon dioxide. , Aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, calcined kaolin, inorganic pigments such as particulate anhydrous silica, colloidal silica, diatomaceous earth, activated clay, styrene microballs, nylon powder, polyethylene powder, Examples include urea / formalin resin fillers and organic pigments such as raw starch particles. The amount used is generally 5 to 30 with respect to 100 parts by weight of the binder component.
It is desirable to adjust within the range of about 0 parts by weight.

The method for preparing the coating liquid for forming the protective layer is not particularly limited, and it is generally prepared by using water as a dispersion medium and mixing a binder, a pigment and the like. Further, in the coating liquid for protective layer, if necessary, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax,
Surfactants such as sodium dioctyl sulfosuccinate (dispersing agents, wetting agents), antifoaming agents, and various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate may be appropriately added. Further, in order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, and an epoxy compound can be used in combination.

Regarding the method for forming the heat-sensitive recording layer or the protective layer,
Is not particularly limited.
Coating, varibar blade coating, pure
Blade coating, rod blade coating,
Short dwell coating, curtain coating
Recording layer by suitable coating method such as coating, die coating, etc.
Coating solution for base material and drying, and then coating solution for protective layer
Is applied and dried. In addition, support
As the body, paper, plastic film, synthetic paper, non-woven
It is used by appropriately selecting from cloth, metal vapor deposition, and the like.
The coating amount of the coating liquid for the recording layer is 1 to 12 g as a dry weight.
/ M²Degree, preferably 2 to 6 g / m²Adjusted in the range
Be done. Further, the coating amount of the protective layer coating liquid is 0.1 on a dry weight basis.
~ 20 g / m ²Degree, preferably 0.5 to 4 g / m²of
Adjusted in range.

If desired, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Furthermore, an undercoat layer may be provided on the support, smoothing treatment such as supercalendering may be applied after each layer is smeared to improve image quality and image density, or an adhesive label may be applied to the back surface of the recording material to form an adhesive label. Various known techniques in the field of producing a thermal recording medium, such as providing a magnetic layer on the back surface of the recording medium, can be added as necessary.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

[Example 1] 1) Preparation of solution A: 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane and 15 parts of 1,2-di (3-methylphenoxy) ethane. , 5% aqueous solution of methylcellulose 15
And 80 parts of water were pulverized with a sand mill until the average particle size became 1 μm. 2) Preparation of solution B 4-hydroxy-4'-isopropoxydiphenylsulfone 30 parts, 5% aqueous solution of methylcellulose 30 parts,
A composition comprising 70 parts of water and water was pulverized with a sand mill until the average particle size became 2 μm. 3) Preparation of coating liquid for thermosensitive recording layer 120 parts of solution A, 130 parts of solution B, fine anhydrous silica 10
Parts, 5 parts of light calcium carbonate, 50 parts of a 25% aqueous solution of a sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone, 10 parts of a 30% dispersion of zinc stearate, and 20 parts of water. Was stirred and mixed to prepare a recording layer coating liquid. 4) The heat-sensitive recording layer coating liquid forming the resulting heat-sensitive recording layer on a high-quality paper having a basis weight of 45 g / m ^2, forming a recording layer coating weight after drying by coating and drying so as to 4g / m ² did.

5) Preparation of coating liquid for protective layer 20 parts of particulate anhydrous silica, 5 parts of light calcium carbonate,
25% aqueous solution of sodium salt of water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone 5
A coating solution for a protective layer was prepared by stirring and mixing 0 part, 10 parts of a 30% zinc stearate dispersion, and 60 parts of water.

6) Formation of Protective Layer The coating solution for protective layer thus obtained was applied on the thermosensitive recording layer so that the coating amount after drying was 1 g / m ² and dried, and then supercalendering was performed to obtain a thermosensitive coating. I got the recording paper.

Example 2 In the preparation of the recording layer coating liquid of Example 1, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
Thermosensitive recording was performed in the same manner as in Example 1 except that 50 parts of a 25% aqueous solution of an ammonium salt of a water-soluble graft copolymer consisting of 85 parts of polymethacrylic acid and 15 parts of silicone was used instead of 50 parts of a 5% aqueous solution. Got the paper.

Example 3 In the preparation of the coating liquid for the recording layer of Example 1, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
Instead of 50 parts of a 5% aqueous solution, 80 parts of a copolymer consisting of 60 parts of maleic anhydride and 20 parts of styrene and silicone 2
A thermal recording paper was obtained in the same manner as in Example 1 except that 40 parts of a 25% aqueous solution of a sodium salt of a water-soluble graft copolymer consisting of 0 parts and 25 parts of a 10% aqueous solution of silicon-modified polyvinyl alcohol were used.

Example 4 In the preparation of the coating liquid for protective layer of Example 1, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
Thermosensitive recording was performed in the same manner as in Example 1 except that 50 parts of a 25% aqueous solution of an ammonium salt of a water-soluble graft copolymer consisting of 85 parts of polymethacrylic acid and 15 parts of silicone was used instead of 50 parts of a 5% aqueous solution. Got the paper.

Example 5 In the preparation of the recording layer coating liquid of Example 4, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
Thermal recording in the same manner as in Example 4 except that 50 parts of a 25% aqueous solution of an ammonium salt of a water-soluble graft copolymer consisting of 85 parts of polymethacrylic acid and 15 parts of silicone was used instead of 50 parts of a 5% aqueous solution. Got the paper.

Comparative Example 1 80 parts of polyacrylic acid and 2 parts of silicone were used in the preparation of the coating liquid for the thermosensitive recording layer of Example 1.
Instead of 50 parts of a 25% aqueous solution of a sodium salt of a water-soluble graft copolymer consisting of 0 parts, 50% of a copolymer consisting of 80 parts of methyl methacrylate and 20 parts of silicone
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 25 parts of emulsion was used.

Comparative Example 2 In the preparation of the coating liquid for the thermosensitive recording layer of Example 1, 80 parts of polyacrylic acid and 2 parts of silicone were used.
Instead of 50 parts of a 25% aqueous solution of a sodium salt of a water-soluble graft copolymer consisting of 0 parts, 125 parts of a 10% aqueous solution of polyvinyl alcohol (trade name: Z-210, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) modified with an acetoacetyl group was used. Other than that,
A thermal recording paper was obtained in the same manner as in Example 1.

[Comparative Example 3] In the preparation of the coating liquid for the heat-sensitive recording layer of Example 1, 80 parts of polyacrylic acid and silicone 2 were used.
Example 1 except that 42 parts of a 30% dispersion of a soap-free self-crosslinking acrylic ester resin was used in place of 50 parts of a 25% aqueous solution of a sodium salt of a water-soluble graft copolymer consisting of 0 parts. Thermal recording paper was obtained in the same manner.

Comparative Example 4 In the preparation of the coating liquid for protective layer of Example 1, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
Instead of 50 parts of 5% aqueous solution, methyl methacrylate 8
A thermal recording paper was obtained in the same manner as in Example 1 except that 25 parts of a 50% emulsion of a copolymer consisting of 0 part and 20 parts of silicone was used.

Comparative Example 5 In the preparation of the protective layer coating liquid of Example 1, 2 parts of the sodium salt of a water-soluble graft copolymer consisting of 80 parts of polyacrylic acid and 20 parts of silicone was used.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 42 parts of a 30% dispersion of a soap-free self-crosslinking acrylic ester resin was used instead of 50 parts of a 5% aqueous solution.

Comparative Example 6 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that the protective layer was not provided. Comparative Example 7 Protective Layer Coating Liquid Polyacrylic Acid 8 of Comparative Example 3
Other than using 42 parts of a 30% dispersion of a soap-free self-crosslinking acrylic ester resin, instead of 50 parts of a 25% aqueous solution of a Na salt of a water-soluble graft copolymer consisting of 0 part and 20 parts of silicone, A thermal recording paper was obtained in the same manner as in Comparative Example 3.

The 12 types of heat-sensitive recording papers thus obtained were subjected to the following evaluation tests, and the results are shown in Table 1. 1) Recording density Using a thermal recording simulator [TH-PDM, manufactured by Okura Electric Co., Ltd.], recording was performed at an applied head energy of 0.3 mJ / dot, and the density of the recorded image obtained was measured using a Macbeth densitometer [RD914, manufactured by Macbeth Co., Ltd. ] It was measured in.

2) Printability Using 0.4 cc of ink for offrin (tack value: 13),
Printing was performed with an RI type printing tester manufactured by Akira Seisakusho, and after passing through a water roll, printing was performed using a roll with ink, and the peeled state of the heat-sensitive recording layer was visually evaluated.

[Evaluation Criteria] A: No peeling of the thermosensitive recording layer was observed. ◯: The thermal recording layer was slightly peeled off. Δ: The thermal recording layer was slightly peeled off. ×: Peeling of the heat-sensitive recording layer was very large.

3) Water resistance After dropping one drop of water on the recording surface, it was rubbed 20 times with a finger to visually judge the degree of peeling of the recording surface. O: Almost no peeling of the recording surface. △: The recording surface was slightly peeled off. X: The recording surface is often peeled off.

4) Fingerprint resistance The recording surface was strongly pressed with a finger with sebum, and the change in density of the recorded image after 3 days was visually judged. ◯: There is almost no change in the density of the recorded image. B: There is a slight change in the density of the recorded image. X: The density of the recorded image changes significantly.

5) Runnability In the method of 1) above, the applied head energy is 0.5 m.
Recording was performed in the same manner by increasing to J / dot, and running performance was evaluated by the loudness of sound (sticking sound) generated during recording. ◎ ・ ・ ・ ・ ・ The running performance is very good. O: Good running performance. × ・ ・ ・ Drivability is poor

6) Head residue The head residue was evaluated by the amount of head residue generated on the thermal head when recording 100 m of thermal recording paper by the method of 1) above. ◎ ・ ・ ・ Head residue is very small. ○: There is little head residue. ×: There are many head meals.

[0049]

[Table 1]

[0050]

As is clear from the results of [Table 1], the thermosensitive recording medium of the present invention was a recording medium excellent in water resistance and printability as well as running property during recording.

Claims (1)

[Claims] 1. A heat-sensitive recording medium comprising a support and a heat-sensitive recording layer containing a colorless or light-colored basic dye and a colorant and a protective layer, wherein the heat-sensitive recording layer and the protective layer contain: A heat-sensitive recording material comprising a water-soluble graft copolymer of a polymer containing at least an ethylenically unsaturated carboxylic acid and silicone.