JPH09202051A - Thermal recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain thermal recording paper reduced in dust generating quantity, in thermal recording paper wherein a thermal recording layer containing a leuco dye, a coupler and an adhesive and a protective layer containing an adhesive are successively provided on raw paper, by adding an epoxidized polyamide resin to the raw paper and the protective layer. SOLUTION: In thermal recording paper wherein a thermal recording layer containing a leuco dye, a coupler and an adhesive and a protective layer containing an adhesive are successively provided on raw paper, being a recording medium reduced in dust generating quantity usable even in a clean room, an epoxidized polyamide resin is added to the raw paper and the protective layer in an amt. of 0.1-10% by wt. of the total solid quantity of the protective layer. This opoxidized polyamide resin is obtained by performing the addition reaction of epichlorohydrin with a secondary amino group of polyamidepolyamine obtained by the dehydrocondensation reaction of a compd. containing a secondary amino group in its molecule and dicarboxylic acid and making the pH of the reaction product acidic by hydrochloric acid.

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 paper utilizing a color-forming reaction between a leuco dye and a color-developing agent, and more particularly to a heat-sensitive recording paper in which paper dust and dust (amount of dust generation) is small. .

[0002]

2. Description of the Related Art A heat-sensitive recording paper, which utilizes a color reaction between a colorless or light-colored leuco dye and a color-developing agent to react both color-forming substances with thermal energy from a thermal head to obtain a recorded image, is often used. Are known. Since such thermal recording paper is relatively inexpensive and the recording device is compact and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computing devices but also in a wide range of fields.

In recent years, the opportunities for working in a clean room have increased with the development of electronics, pharmaceuticals, and precision machinery industries, and there is a demand for a recording medium with a small amount of dust that can be used in a clean room. , And, if necessary, with commercially available thermal recording paper that has a coating layer such as a protective layer in order, when paper is torn or rubbed, paper dust and dust generated from the base paper and coating layer are generated. Not suitable for use in a clean room where a large amount of dust is required and high cleanliness (cleanliness) is required.

As a method for obtaining a heat-sensitive recording paper having a small amount of dust generation, Japanese Patent Publication No. 4-34956 uses a base paper containing no filler and the content of the adhesive in the heat-sensitive recording layer is 20 to 30% by weight. However, the present situation is that sufficient effects have not been obtained. Further, a thermosensitive recording medium containing an epoxidized polyamide resin as a waterproofing agent for a water-soluble polymer having a carboxyl group in a protective layer is disclosed in JP-A-59-59.
No. 162088, JP-A-60-104598, and JP-A-62-142685, the epoxidized polyamide resin has an effect of suppressing paper dust and dust generated from the thermal recording paper. There is no description suggesting that it will be done.

[0005]

[Problems to be Solved by the Invention]

An object of the present invention is to provide a thermosensitive recording paper which produces a particularly small amount of dust.

[0007]

The present inventor has found that on a base paper,
In a thermal recording paper in which a thermosensitive recording layer containing a leuco dye, a colorant and an adhesive, and a protective layer containing an adhesive are sequentially provided, by incorporating an epoxidized polyamide resin in the base paper and the protective layer. The inventors have found that the above problems can be effectively solved, and completed the present invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a thermosensitive recording paper in which a thermosensitive recording layer containing a leuco dye, a coloring agent and an adhesive, and a protective layer containing an adhesive are sequentially provided on the base paper. Also, the protective layer contains an epoxidized polyamide resin. With such a constitution, a heat-sensitive recording paper with an extremely small amount of dust can be obtained.

The base paper used in the present invention is obtained by adding an epoxidized polyamide resin to beaten chemical pulp, making a paper with a paper machine, and then calendering it if necessary. The addition amount of the epoxidized polyamide resin is not particularly limited, but it is desirable to add about 0.1 to 2.0% by weight based on the total solid amount of the chemical pulp in the pulp slurry before papermaking. If the epoxidized polyamide resin is less than 0.1% by weight with respect to the chemical pulp, the filler and fine fibers internally added to the base paper may generate dust, and if it exceeds 2.0% by weight, the recording density is There is a risk that it will deteriorate or that a uniform base paper cannot be made. The basis weight of the base paper is 15 to 200 g / m ² , preferably 20 to 80
g / m ² is used. As a method for beating the chemical pulp, it is preferable to treat a pulp suspension having a pulp concentration of 0.2 to 5% with a beating machine or a sand mill so that the freeness value (CSF) becomes 500 cc or less. Further, in order to glassine the base paper, the freeness value is set to 200 cc or less, and a water-soluble polymer such as polyvinyl alcohol, starch or carboxymethyl cellulose is internally added or size-pressed to obtain a linear pressure of 200 Kg weight / c.
m, preferably 500 kgf / cm, and may be treated with a metal roll and a calender composed of a metal roll or an elastic roll.

The epoxidized polyamide resin is obtained by dehydration condensation reaction of a dicarboxylic acid (for example, adipic acid) with a secondary amino group (for example, diethylenetriamine) in the molecule, and epichlorohydrin is added to the secondary amino group of the polyamide polyamine. It can be obtained by acidifying the pH with hydrochloric acid after the addition reaction.

Further, an organic solvent coating liquid in which a resin is dissolved may be applied and dried on the base paper to form a resin layer in order to reduce the paper dust generated from the base paper. As such a resin,
For example, methyl acrylate resin, ethyl acrylate resin,
Acrylic ester resins such as methyl methacrylate resin, vinyl acetate resins, polyester resins, urethane resins, butyral resins, polystyrene, copolymers containing styrene and methyl methacrylate as main components, styrene and ethyl methacrylate. And a copolymer containing styrene and butadiene as a main component, a copolymer containing styrene and methyl acrylate as a main component, a copolymer of vinyl chloride and vinyl acetate, and a phenol resin And so on.

Examples of the organic solvent used in the organic solvent coating solution include toluene, methyl ethyl ketone, butyl acetate, ethyl acetate, ethanol, isopropyl alcohol and xylene.

Various leuco dyes are known as the leuco dye contained in the heat-sensitive recording layer, and the following are exemplified.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
Blue-coloring dyes such as -methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide and 3-diethylamino-7-dibenzylamino-benzo [a] fluorane; 3- (N-ethyl) -N-p-tolyl) amino-7-N-methylanilinofluorane, 3-
Green-coloring dyes such as diethylamino-7-anilinofluorane;

3-diethylamino-7-methylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane,
Rhodamine (p-chloroanilino) lactam, 3- (N
-Ethyl-p-toluidino) -7-methylfluoran,
Red color-forming dye such as 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide;

3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6
-Methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3
-Di (n-amyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-di (n-butyl) amino-7
-(O-chloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3-
Di (n-butyl) amino-7- (o-fluoroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-p-toluidino) -6- Methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3 −
Black coloring dyes such as di (n-butyl) amino-6-methyl-7-m-toluidinofluorane and 3-piperidino-6-methyl-7-anilinofluorane. Of course, it is not limited to these, and two or more kinds may be used in combination as required. The leuco dye is contained in the heat-sensitive recording layer in an amount of 5 to 40% by weight, preferably 10 to 30% by weight.
It is desirable to use in.

As the colorant used in combination with the leuco dye, various known ones can be used, for example, 4,4'-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2, 2-bis (4-
Hydroxyphenyl) -4-methylpentane, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3- Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenyl sulfone, 4-hydroxyphenyl-4′-benzyloxyphenyl sulfone, 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, di (4-hydroxy-3-methylphenyl) sulfide, 2,2 '
-Phenolic compounds such as thiobis (3-tert-octylphenol); thiourea compounds such as N, N'-di-m-chlorophenylthiourea;4,4'-bis (p
-Toluenesulfonylaminocarbonylamino) diphenylmethane, N- (p-toluenesulfonyl) -N'-
(P- tolyl) compound having a -SO ₂ NH- bond in the molecule such as urea; p-chlorobenzoic acid zinc, 4- [2-
Aromatic such as zinc (p-methoxyphenoxy) ethyloxy] salicylate, zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, and zinc 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylate. Examples thereof include zinc salts of carboxylic acids.

In the present invention, the use ratio of the leuco dye and the coloring agent in the heat-sensitive recording layer is not particularly limited, but generally 1 to 7 parts by weight to 1 part by weight of the leuco dye,
Preferably, about 1 to 4 parts by weight of a coloring agent is used.

Examples of the adhesive include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic,
Polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt,
Ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, natural rubber latex, styrene / butadiene copolymer latex, acrylonitrile / butadiene copolymer latex, methyl methacrylate /
At least one of butadiene-based copolymer latex, polychloroprene-based latex, vinyl acetate-based latex, polyurethane-based latex, ethylene / vinyl acetate-based latex, etc. is 15 to 15% based on the total solid content of the heat-sensitive recording layer.
40 wt%, preferably about 20 to 35 wt% is added.

Further, a sensitizer for increasing recording sensitivity and a preservative improving material for enhancing preservability of recorded images may be added. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, ethylenebisstearic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, and terephthalate. Acid dibenzyl, 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, 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-acetophenetizide,
Examples include N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like.

Specific examples of the storage stability improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylenebis (4-methyl-6-tert-butylphenol). , 2,2'-methylenebis (4,6-di-tert-butylphenol), 2,
2'-ethylidene bis (4,6-di-tert-butylphenol), 2,2'-methylene bis (4-methoxy-6)
-Tert-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 (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), 2,2-bis (4
-Hydroxy-3,5-dichlorophenyl) propane,
Hindered phenol compounds such as 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane,
N, N'-di-2-naphthyl-p-phenylenediamine, sodium 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, 2,2'-methylenebis (4,6-di) -Tert-butylphenyl) magnesium phosphate, 2- (2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-
5'-tert-butylphenyl) benzotriazole and the like.

The amounts of these sensitizers and storability improvers to be used are not particularly limited, but it is generally desirable to adjust the amount to 4 parts by weight or less per 1 part by weight of the color developing agent.

The heat-sensitive recording layer coating liquid for forming the heat-sensitive recording layer generally uses water as a dispersion medium, and a leuco dye, a color former, a sensitizer, a stirrer such as a ball mill, an attritor or a sand mill, and a pulverizer. It is prepared by finely dispersing the storability improver together or separately and then adding an adhesive.

In the heat sensitive recording layer coating liquid, if necessary,
Various auxiliaries can be added, for example, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate, surfactants such as fatty acid metal salts, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin. , Aluminum hydroxide, amorphous fine particle silica, styrene microballs, nylon powder, polyethylene powder,
A pigment such as a urea / formalin resin filler, other defoaming agents, fluorescent dyes, coloring dyes and the like are appropriately added. Furthermore,
It is also possible to add the epoxidized polyamide resin contained in the base paper and the protective layer to the coating liquid for the heat-sensitive recording layer.

By providing a protective layer containing an adhesive and an epoxidized polyamide resin on the thermosensitive recording layer, dust generated from the thermosensitive recording layer and the protective layer can be suppressed. The amount of the epoxidized polyamide resin used is not particularly limited, but is 0.1 to 10% by weight, preferably about 0.5 to 5% by weight, particularly 0.5 to 2% by weight, based on the total solid amount of the protective layer.
Is desirable. If it is less than 0.1% by weight, the effect of suppressing the generation of dust may be lowered, and if it exceeds 10% by weight, the recording density may be lowered.

Examples of the adhesive used in the protective layer include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and silicon. Modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt,
Styrene-maleic anhydride copolymer salt, ethylene-acrylic acid copolymer salt, styrene-acrylic acid copolymer salt,
Examples include urea resin, melamine resin, amide resin, acrylic resin, polyester polyurethane resin, and the like.

Among them, carboxy-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt,
It forms a strong film against an adhesive having a carboxyl group such as a styrene-maleic anhydride copolymer salt or an ethylene-acrylic acid copolymer salt, and is particularly preferably used. The amount of the adhesive used in the protective layer is preferably about 25 to 95% by weight based on the total solid amount of the protective layer.

A pigment may be added to the protective layer in order to improve printability and recording runnability. Specific examples of the pigment include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined kaolin, inorganic pigments such as colloidal silica, and styrene microballs. , Nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch particles. The amount used is preferably about 5 to 300% by weight with respect to the adhesive.

Further, in the protective layer, if necessary, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, etc., and a surfactant (dispersing agent, such as dioctyl sodium succinate, etc.). Various auxiliaries such as a wetting agent), a defoaming agent, and a water-soluble polyvalent metal salt such as potassium alum and aluminum acetate may be appropriately added.

The protective layer coating liquid for forming the protective layer is
It can be obtained by stirring and mixing with water as a dispersion medium, an adhesive, an epoxidized polyamide resin, and optionally a pigment, a lubricant, a dispersant and the like.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited, and suitable examples include air knife coating, varibar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating and die coating. Depending on the coating method, the dry weight of the coating liquid for the heat-sensitive recording layer is ² to 12 g / m ² , preferably 3 to 1
0 g / m ² or about 0.5 wt.
It is formed by sequentially coating and drying on a base paper containing an epoxidized amide resin so as to be about 7 to 7 g / m ² , preferably about 1 to 4 g / m ² .

The heat-sensitive recording paper of the present invention may be provided with a protective layer on the surface opposite to the heat-sensitive recording layer side to correct curl. Further, various known techniques in the field of heat-sensitive recording paper production can be added as necessary, for example, smoothing treatment such as super calendering is applied after coating each layer such as the heat-sensitive recording layer and the protective layer.

[0032]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples are parts by weight and% by weight, respectively.

Example 1 Production of base paper 20 parts and 2 parts of LBKP beaten to a freeness of 470 cc
Talc was added to a pulp suspension obtained by blending 80 parts of NBKP beaten to 70 cc so that the paper ash content was 8%, and rosin size was used as a sizing agent in an amount of 0.3 part with respect to absolutely dry pulp and a sulfuric acid band 1. Add 5 parts p
After adjusting H to 4.8, 3.0 parts of a 30% aqueous solution of an epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Co., Ltd.) was added, and a fourdrinier cylinder cylinder dryer paper machine was used for papermaking. , An aqueous solution of polyvinyl alcohol
Size press was performed so that the weight was 5 g / m ² . Treated with a calender, porosity is 36%, basis weight 63g / m ²
I got the base paper.

Preparation of Solution A: 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 15 parts of 1,2-di (3-methylphenoxy) ethane, 5% of methylcellulose. Aqueous solution 5
Parts and 60 parts of water were pulverized with a sand mill until the average particle size became 1 μm.

Preparation of Solution B A composition consisting of 35 parts of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 60 parts of water has an average particle diameter of 1.5 μm in a sand mill. Crushed until.

Preparation of Resin Layer Coating Liquid After dispersing 1 part of amorphous silica in 80 parts of toluene, a copolymer of vinyl chloride and vinyl acetate (trade name: Kanevirac L-CN, acetic acid for vinyl chloride) was prepared. 100 vinyl
90 parts by weight, containing 37% by weight and having a solid concentration of 37%, manufactured by Kanegafuchi Chemical Co., Ltd.

Preparation of coating liquid for heat-sensitive recording layer 100 parts of solution A, 30 parts of solution B, 10% aqueous solution of polyvinyl alcohol (trade name: PVA-110, manufactured by Kuraray Co., Ltd.) 1
A composition consisting of 50 parts, 10 parts of light calcium carbonate and 30 parts of water was mixed and stirred to obtain a coating liquid for heat-sensitive recording layer.

Preparation of Coating Liquid for Protective Layer 80 parts of kaolin, 10% aqueous solution of silicon-modified polyvinyl alcohol (trade name: R1130, manufactured by Kuraray Co., Ltd.) 400
Part, epoxidized polyamide resin (trade name: WS-53
5, 30% aqueous solution of 30% aqueous solution of zinc stearate, and 140 parts of water were mixed and stirred to obtain a coating liquid for protective layer.

Production of Thermal Recording Paper On one side of the above-mentioned base paper, the coating amount after drying of the resin layer coating liquid, the thermal recording layer coating liquid and the protective layer coating liquid was 4 g / m ² , 5
g / m ² and 3 g / m ² and so as to sequentially applied and dried to the resin layer, after forming the heat-sensitive recording layer and a protective layer to obtain a heat-sensitive recording paper was smoothed by super calender.

Example 2 In the production of the base paper of Example 1, 30% of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Co., Ltd.)
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 3.0 parts of the aqueous solution was changed to 6.0 parts.

Example 3 In the production of the base paper of Example 1, 30 of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Co., Ltd.) was used.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 3.0 parts of 0.5% aqueous solution was changed to 0.5 parts.

Example 4 In the preparation of the coating liquid for the protective layer of Example 1, except that 12 parts of 3.0 parts of a 30% aqueous solution of an epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC) were used. In the same manner as in Example 1, a thermal recording paper was obtained.

Example 5 In the preparation of the coating liquid for the protective layer of Example 1, 3.0 parts of a 30% aqueous solution of an epoxidized polyamide resin (trade name: WS-535, manufactured by Japan PMC) was used as 0.1 part. A thermal recording paper was obtained in the same manner as in Example 1 except for the above.

Example 6 In the preparation of the coating liquid for the protective layer of Example 1, a carboxyl group-modified polyvinyl alcohol (trade name) was used instead of 400 parts of a 10% aqueous solution of silicon-modified polyvinyl alcohol (trade name: R1130, manufactured by Kuraray Co., Ltd.). A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 660 parts of a 6% aqueous solution of KL-318, manufactured by Kuraray Co., Ltd.) was used.

Example 7 A thermal recording paper was obtained in the same manner as in Example 1 except that the resin layer was not provided in the production of the thermal recording paper of Example 1.

Comparative Example 1 In the production of the base paper of Example 1, 30 of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Co., Ltd.) was used.
% Thermosensitive recording paper was obtained in the same manner as in Example 1 except that 3.0 parts of aqueous solution was not added.

Comparative Example 2 In the formation of the protective layer of Example 1, 3 of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Ltd.) was used.
A thermal recording paper was obtained in the same manner as in Example 1 except that 3.0 parts of 0% aqueous solution was not added.

Comparative Example 3 In the production of the base paper of Example 1, 30 of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC Co., Ltd.) was used.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 4.5 parts of a 20% aqueous solution of a polyacrylic amide resin was used instead of 3.0 parts of a 10% aqueous solution.

Comparative Example 4 In the preparation of the coating liquid for the protective layer of Example 1, urea formalin resin was used instead of 3.0 parts of a 30% aqueous solution of epoxidized polyamide resin (trade name: WS-535, manufactured by Nippon PMC). A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 4.5% of 20% aqueous solution was used.

The thermal recording paper thus obtained was subjected to the following quality evaluation tests, and the results are shown in Table 1.

[Cleanliness] Rubbing test Once in a clean measuring device (50 cm × 50 cm × 50 cm) which allows hand operation of A5 size test pieces from outside, once
Knead by hand for 2 minutes at a speed of 0 sec.

Rubbing test A5 size test pieces were placed in a measuring instrument with the front side and the back side overlapped 1
Rub by hand for 2 minutes at a speed of 2 seconds.

Tear Test A5 size test pieces are torn at 5 cm intervals and then tested in the same manner as the kneading test.

The amount of dust (dust) generated in the measuring instrument by the above test is measured by a dust counter (trade name: Rion K).
C-01A), and the cleanliness was represented by the total number of particles of 0.3 μm or more (in one cubic foot).

[Recording Density] Thermal recording evaluation machine (TH-PM
D type, manufactured by Okura Electric Co., Ltd., and applied energy 0.4
The recording density of the recorded image obtained by printing at mJ / dot was measured in a visual mode with a Macbeth densitometer (RD-914R type, manufactured by Macbeth Co.).

[0056]

[Table 1]

[0057]

As shown in Table 1, the thermosensitive recording paper of the present invention has a characteristic that the amount of dust generated is small.

Claims (2)

[Claims] 1. A thermosensitive recording paper comprising a base paper, a thermosensitive recording layer containing a leuco dye, a coloring agent and an adhesive, and a protective layer containing the adhesive, which are provided in this order in the base paper and the protective layer. A thermosensitive recording paper containing an epoxidized polyamide resin. 2. The heat-sensitive recording material according to claim 1, wherein the epoxidized polyamide resin is contained in an amount of 0.1 to 10% by weight based on the total solid amount of the protective layer.