JPH07290821A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance the preservability of a recording image and the water resistance of a recording layer and to reduce the adhesion of refuse to a head by adding a soap free polyethylene emulsion of which the m.p. is specific temp. or higher to the recording layer in a thermal recording material. CONSTITUTION:A soap free polyethylene emulsion with an m.p. of 6 deg.C or higher is added to a recording layer containing a colorless or light-colored basic dye and a coupler. The polyethylene emulsion is obtained by adding a small amt. of an ethylenic unsaturated carboxylic acid monomer to an ethylene monomer to subject both monomers to polymerization reaction and neutralizing the reaction product with alkali and has a particle size of 0.01-10mum. The addition amt. of the emulsion is set to 2-30% by wt. of the total solid amt. of the recording layer. By this constitution, a thermal recording material excellent in the preservability of a recording image and the water resistance of the recording layer and reduced in the adhesion of refuse to a head can be obtained.

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 utilizing a colorless or light basic dye, a coloring agent and a color reaction.
The present invention relates to a heat-sensitive recording material which has excellent storability of a recorded image and water resistance of a recording layer, and has less head dust adherence.

[0002]

2. Description of the Related Art A heat-sensitive recording material 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 recorded image is often used. Are known. Since such a thermosensitive recording medium is relatively inexpensive, the recording device is compact, and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

For example, one of the fields of use thereof is a heat-sensitive recording label for a POS (point of sales) system of a retail store, etc., but with the expansion of the system,
In addition to conventional food labels, which have their missions completed in a short period of time as in the past, the number of applications in which they are attached to products for a long period of time is increasing. However, in such an application, the recorded image is discolored or the recording layer is peeled off due to contact with water, wraps, oil, etc. As a result, the product image is significantly impaired. For this reason, it is required that the heat-sensitive recording material has preservability with respect to water resistance, plasticizer resistance, oil resistance and the like.

Further, there is a demand for a thermal recording medium capable of recording at a recording speed of 10 seconds or less in A4 size for a thermal fax, and 120 characters / second or more for a thermal printer. There is a new problem that the lees adhere to the head and a uniform recorded image cannot be obtained.

[0005]

A method of adding paraffin wax to the recording layer in order to improve the head residue is described in JP-A-1-133787, but it is used when finely dispersing the paraffin wax. Due to the effects of emulsifiers and the like, sufficient water resistance is not obtained. An object of the present invention is to provide a heat-sensitive recording material which is excellent in storability of a recorded image and water resistance of a recording layer and which has less head dust adherence.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium having a recording layer containing a colorless or light-colored basic dye and a coloring agent on a support, and a melting point in the recording layer. It was found that the above problems can be solved by containing a soap-free polyethylene emulsion having a temperature of 60 ° C. or higher, and the present invention has been completed.

[0007]

A soap-free polyethylene emulsion having a melting point of 60 ° C. or higher, which is contained in a recording layer having a colorless or pale basic dye and a colorant, is a small amount of an ethylenically unsaturated carboxylic acid monomer, for example, in an ethylene monomer. It can be obtained by adding acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic anhydride, styrenesulfonic acid, etc. to cause a polymerization reaction and then neutralizing with an alkali. The particle size of polyethylene emulsion is
0.01 to 10 μm is preferable, and 0.02 to 3 μm is more preferable. The amount of the specific polyethylene emulsion added to the recording layer is 2 with respect to the total solid amount of the recording layer.
It is desirable to adjust in the range of -30% by weight, preferably 5-20% by weight. If the melting point of soap-free polyethylene is less than 60 ° C., super dust may be generated when the recording layer is smoothed by a super calender after forming the recording layer, and uniform smoothness may not be obtained. When an emulsifier is contained in the polyethylene emulsion, the effect of the emulsifier may be such as causing background fog or lowering the water resistance of the recording layer.

In the present invention, as the colorless or monochromatic basic dye contained in the heat-sensitive recording layer, various known dyes can be mentioned, specifically, for example, 3,3-bis (p-dimethylaminophenyl). -6-Dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl)
-3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] fluorane, 3- (N-ethyl-
Np-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- (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-fluorophenylamino) fluorane, 3
-(N-ethyl-N-isobutyl) amino-7- (p-
Trifluoromethylanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isobutyl) amino-7- (o-trifluoromethylanilino) fluorane , 3- (N-methyl-N-cyclohexyl) amino-
7- (o-trifluoromethylanilino) fluorane,
3- (N-ethyl-p-toluidino) -6-methyl-7
-Anilinofluorane, 3- (N-ethyl-N-furfurylamino) -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-p- (p-anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3,6, -bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino)
Phthalide, 3- (N-ethyl-N-isobutyl) amino-7- (p-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isobutyl) amino-7-
(O-trifluoromethylanilino) fluorane, 3-
(N-ethyl-N-isoamyl) amino-7- (p-trifluoromethylanilino) fluorane, 3-di (n-
Butyl) amino-7- (m-trifluoromethylanilino) fluorane and the like. Two or more of these dyes may be used in combination. Generally, the content of the basic dye in the heat-sensitive recording layer is preferably about 5 to 20% by weight based on the dry weight of the heat-sensitive recording layer.

Examples of the color former used together with the basic dye include the following known ones. 4-te
rt-Butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidene diphenol, 4
-Phenylphenol, 4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol (bisphenol A), hydroquinone, 4,4'-
Cyclohexylidene bisphenol, 4,4 '-(1,
3-dimethylbutylidene) bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methyl-pentane, 4,4'-dihydroxydiphenylsulfide,
4,4'-dihydroxydiphenyl sulfone, 2,4 '
-Dihydroxydiphenyl sulfone, 4-hydroxy-
4'-methyldiphenyl sulfone, 4-hydroxy-
4'-methoxydiphenyl sulfone, 4-hydroxy-
4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'-trimethylene diphenyl sulfone,
4-hydroxy-3 ', 4'-tetramethylene diphenyl sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 1,3-di [2- ( 4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, p-hydroxy-N- (2-phenoxyethyl). Benzenesulfonamide, 1,8-bis (4
-Hydroxyphenylthio) -3,6-dioxa-octane, (4-hydroxyphenylthio) acetic acid-2- (4
-Phenolic compounds such as hydroxyphenylthio) ethyl ester, novolac type phenol resin, phenol polymer and the like.

Further, as a coloring agent, --SO ₂ NHCX--
[In the formula, X represents an oxygen atom or a sulfur atom. ] When an aromatic compound having a group represented by the following is used, the action and effect of a specific polyethylene emulsion, that is, the head meal is remarkably improved. Examples of the aromatic compound having a group represented by —SO ₂ NHCX— include those described in JP-A-5-32061 and JP-B-5-143753. Especially 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane and N
Highly effective for-(p-toluenesulfonyl) -N'-phenylurea. The amount of the coloring agent used is 50 to 500% by weight based on the colorless or light-colored basic dye.
Is preferred.

In the heat-sensitive recording material of the present invention, a sensitizer can be added to the recording layer according to the purpose. Specific examples of the sensitizer include stearic acid amide and methoxycarbonyl-N-stearic acid. Benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, Benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m- Terphenyl, p-benzylbiphenyl, tri Biphenyl ether, di (p- methoxyphenoxy) 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-diphenoxy Ethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane,
p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-
Examples include acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of about 400% by weight or less based on the color developing agent.

Further, a preservative improving agent may be used in combination depending on the purpose in order to further enhance the preservability of the recorded image as long as the effects of the present invention are not impaired. Specific examples of such a shelf stability improver include, for example, 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'-methylenebis (4-methoxy-6-tert-butylphenol), 2,2'-methylenebis (6-tert-butylphenol) , 4,4'-thiobis (2-methyl-6-tert-butylphenol),
4,4'-thiobis (5-methyl-6-tert-butylphenol), 4,4'-thiobis (2-ethyl-6-te
rt-butylphenol), 4,4'-butylidene bis (6-tert-butyl-m-cresol), 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-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,
5-dichlorophenyl) propane, 2,2-bis (4-
Epoxy compounds such as hindered phenol compounds such as hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenyl sulfone, diglucidyl terephthalate, and bisphenol A type epoxy resin , 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4
-[Α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-
Di-tert-butylphenyl) sodium phosphate and the like can be mentioned.

In order to prepare a coating liquid for a recording layer containing these compounds, generally, water is used as a dispersion medium, and a basic dye and the above-SO ₂ NHCX- [are mixed with a stirrer / pulverizer such as a ball mill, attritor or sand mill. In the formula, X represents a member selected from oxygen atom and sulfur atom. ] A group-containing compound, and further, a sensitizer and the like added as necessary are dispersed together or separately to prepare a coating liquid.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose,
Carboxymethyl cellulose, gelatin, casein, arabic gum, polyvinyl alcohol, diisobutylene
Maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, with these inorganic pigments 10 to 40% by weight of the total solid content of the composite emulsion, preferably 15
It is used in an amount of about 30% by weight.

Various auxiliaries can be added to the coating liquid, for example, dispersion of sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate ester, sodium salt, alginate salt, fatty acid metal salt and the like. Agents, benzophenone-based, triazole-based and other UV absorbers, other defoamers, fluorescent dyes,
Examples include coloring dyes. Further, if necessary, a lubricant such as zinc stearate or calcium stearate, an inorganic pigment such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay can be added. Is.

In the present invention, the method for forming the heat-sensitive recording layer is not particularly limited, and the heat-sensitive recording layer can be formed according to a conventionally known and commonly used technique, for example, air knife coating, varibar blade coating, pure blade coating, rod blade coating. , A short dwell coating, a curtain coating, a die coating and the like, and a method of coating and drying the recording layer coating liquid on the support. The support may be appropriately selected from paper, plastic film, synthetic paper, non-woven fabric, metal deposit, etc., and used. The recording layer coating solution 2~12g / m ² coating amount by dry weight of, is regulated preferably in the range of about 3 to 10 g / m ^2.

If necessary, a protective layer may be provided on the recording layer and the back side of the thermosensitive recording medium to further improve the storage stability. Further, in the field of thermosensitive recording medium production, an undercoat layer may be provided on the support, smoothing treatment such as super calendering may be applied after coating each layer, or adhesive treatment may be applied to the back surface of the recording medium to form an adhesive label. Various known techniques can be added as necessary.

[0018]

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, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized with a sand mill until the average particle size became 1.5 μm or less.

Preparation of solution B A composition consisting of 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle diameter became 2 μm or less. did.

Preparation of Solution C A composition consisting of 20 parts of 4-hydroxy, 4'-isopropoxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle size became 2 μm or less. did.

Formation of Recording Layer 55 parts of solution A, 80 parts of solution B, 230 parts of solution C 80 parts of 10% aqueous solution of polyvinyl alcohol, and calcium carbonate 35
Part, soap-free polyethylene emulsion (trade name: CW-200-5, melting point 80 ° C., solid concentration 40%,
(Manufactured by Futaba Chemical Co., Ltd.) 20 parts are mixed and stirred, and the obtained coating liquid is applied to one surface of a high-quality paper of 60 g / m ² at a coating amount of 6 g / dry.
A recording layer was formed by coating and drying so as to have a surface area of m ^2, and a super calendering treatment was performed to obtain a heat-sensitive recording material.

Example 2 Soap-free polyethylene emulsion (trade name: CW-200-5, melting point 80)
Soap-free polyethylene emulsion (trade name: CW-2) instead of C, solid concentration 40%, manufactured by Futaba Chemical Co., Ltd.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 00-11, melting point 70 ° C., solid concentration 40%, manufactured by Futaba Chemical Co., Ltd. was used.

[Example 3] In the preparation of solution B, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane was used instead of 4-hydroxy, 4'-isopropoxydiphenylsulfone. A thermal recording material was obtained in the same manner as in Example 1.

Example 4 In preparation of solution B, 4-hydroxy, 4'-isopropoxydiphenylsulfone 2
4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane 10 instead of 0 part
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 10 parts of N- (p-toluenesulfonyl) -N'-phenylurea was used.

Comparative Example 1 Soap-free polyethylene emulsion (trade name: CW-200-5, melting point 80)
C., solid concentration 40%, Futaba Chemical Co., Ltd.) 20 parts emulsifier-containing paraffin wax emulsion (trade name:
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 27 parts of hydrin P-7, melting point 60 ° C., solid concentration 30%, manufactured by Chukyo Yushi Co., Ltd.) was used.

Comparative Example 2 Soap-free polyethylene emulsion (trade name: CW-200-5, melting point 80)
C., solid concentration 40%, Futaba Chemical Co., Ltd.) 20 parts polyethylene emulsion emulsified with anionic and nonionic emulsifiers (melting point 50.degree. C., solid concentration 30)
%) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 27 parts were used.

The following six types of thermal recording materials were subjected to the following quality evaluation tests, and the results are shown in Table 1. [Evaluation] [Color density] The color density of the recorded image obtained by printing with a thermal recording evaluation machine (TH-PMD type, manufactured by Okura Electric Co., Ltd., applied energy 0.4 mJ / dot) was measured by a Macbeth densitometer (manufactured by Macbeth Co.). , RD-9
14R type) was measured in visual mode. [Oil resistance] The thermal recording material after recording by the above method was immersed in salad oil and left at room temperature for 3 hours, and the density of the residual image was measured with a Macbeth densitometer (visual mode) to obtain oil resistance. Was evaluated.

[Head Crushability] After printing for 30 m with a thermal recording evaluation machine (TH-PMD type, Okura Electric Co., Ltd., applied energy 0.4 mJ / dot),
The degree of head meal was visually determined. Evaluation criteria There is almost no head meal.・ ・ ・ ○ Head meal adheres slightly.・ ・ △ There are many head meals. ... ×

[Water resistance] A water drop was dropped on the surface of the recording paper and rubbed with a finger 10 times to visually determine the degree of peeling of the recording layer. Evaluation criteria The surface does not come off at all.・ ・ ・ ○ The surface is peeled off. ... ×

[0031]

[Table 1]

[0032]

As is clear from the results shown in Table 1, all of the heat-sensitive recording materials of the present invention were excellent in storage stability, water resistance and head residue.

[Procedure amendment]

[Submission date] March 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Preparation of solution B 4-hydroxy-4'-isopropoxydiphenyl sulphate
A composition consisting of 20 parts of phon , 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle size was 2 μm or less.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Preparation of liquid C A composition consisting of 20 parts of 1,2-di (3-methylphenoxy) ethane , 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle size became 2 μm or less. did.

Claims (2)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein the recording layer contains a soap-free polyethylene emulsion having a melting point of 60 ° C. or higher. A heat-sensitive recording material comprising: 2. A coloring agent is —SO ₂ NHCX— [wherein X is
Represents an oxygen atom or a sulfur atom. ] The heat-sensitive recording material according to claim 1, which is an aromatic compound having a specific functional group represented by: