JP2003103929A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a thermal recording material which controls texture fogging, has high sensitivity, and is excellent preservation properties. SOLUTION: In the thermal recording material, a heat-sensitive coloring layer containing a usually colorless or faintly colored coloring compound, a developing compound capable of coloring the coloring compound when heated, and a sensitizer as main components is formed on a support. The coloring layer contains 1,2-bis(phenoxymethyl)benzene and a carboxyl group-containing styrene-acrylic copolymer and/or an styrene-acrylic copolymer polymerized by using its ammonium salt as an emulsifier.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material. More specifically, it has high sensitivity and low background fog,
The present invention relates to a heat-sensitive recording material having excellent storage properties. [0002] Generally, a thermosensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance into fine particles, mixing the two, and then adding a binder, a sensitizer, and a filler. Additives such as lubricants, lubricants, etc. to make a coating liquid, applied to paper, film, synthetic paper, etc., by heating, the chemical reaction that occurs when one or both of the leuco dye and developer are melted and contacted A color recording record is obtained. For color development of the heat-sensitive recording sheet, a thermal printer or the like having a built-in thermal head is used. Compared to other recording methods, this thermal recording method is (1) no noise during recording, (2) there is no need for development and fixing, (3) maintenance-free, and (4) machines are relatively inexpensive. By features such as
Facsimile field, computer output, printer field such as calculator, recorder field for medical measurement,
It is widely used in the field of automatic ticket vending machines, the field of heat-sensitive recording labels, and the like. [0003] In recent years, the use of POS systems in retail stores and supermarkets and automated systems in transportation have increased the use of labels, tickets, coupons, and the like. In these applications, it is desired that the heat-sensitive recording material is further improved in storage stability such as heat resistance, water resistance and plasticizer resistance. The demand for high-speed recording has further increased, and there has been a strong demand for the development of a heat-sensitive recording material that can sufficiently cope with high-speed recording. However, in general, when the sensitivity of the heat-sensitive recording material is increased and the thermal responsiveness is improved, background fogging occurs. Is easy to appear. Conventionally, various methods have been proposed to improve the heat responsiveness and to further improve the preservability, but none of them have been satisfactory. [0004] The object of the present invention is as described above.
It is to solve the disadvantages of the prior art. That is, it is an object of the present invention to provide a heat-sensitive recording material having high sensitivity, little background fog, and excellent storage stability. The present inventors have made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to (1) a thermosensitive recording material comprising, on a support, a thermochromic layer mainly composed of a colorless or pale-colored color-forming compound and a color-developing compound capable of coloring the color-forming compound when heated. In the thermosensitive coloring layer,
A thermosensitive recording comprising 1,2-bis (phenoxymethyl) benzene, a styrene-acrylic copolymer containing a carboxyl group and / or a styrene-acrylic copolymer polymerized using an ammonium salt thereof as an emulsifier. Material, DETAILED DESCRIPTION OF THE INVENTION The thermosensitive coloring layer in the present invention is usually a colorless or pale-colored coloring compound, a developing compound,
-A main component is a styrene-acrylic copolymer obtained by polymerizing bis (phenoxymethyl) benzene, a carboxyl group-containing styrene-acrylic copolymer and / or an ammonium salt thereof as an emulsifier. In the present invention, 1,2-bis (phenoxymethyl) benzene is used as a sensitizer, and a styrene-acrylic copolymer obtained by polymerizing a carboxyl group-containing styrene-acrylic copolymer and / or an ammonium salt thereof as an emulsifier is bound. Although it functions as an agent, other sensitizers (thermally fusible compounds) and binders may be used in combination as necessary, and if necessary, fillers and other additives are added. Thus, a thermosensitive coloring layer is prepared. In forming the thermosensitive coloring layer in the present invention, the color-forming compound is usually 1 to 50% by weight, preferably 5 to 30% by weight, and the color-developing compound, 1,2-bis (phenoxymethyl) benzene, is usually used. 1 to 80% by weight, preferably 5 to 40% by weight, respectively, carboxyl group-containing styrene.
Acrylic copolymer and / or styrene / acrylic copolymer obtained by polymerizing ammonium salt thereof as an emulsifier,
Usually 0.5 to 50% by weight, preferably 2 to 20% by weight,
The sensitizer, the binder, and the filler are each usually 0 to 80% by weight, and the other lubricants, surfactants, defoamers, ultraviolet absorbers, and the like are each in an arbitrary ratio, for example, usually 0 to 30% by weight, respectively. (% By weight is the weight ratio of each component in the thermosensitive coloring layer). As a further preferred embodiment, among the above-mentioned compositions, the amount of the color-developing compound is usually 0.5 to 20 times, preferably 1 to 5 times the amount of the color-forming compound by weight.
1,2-bis (phenoxymethyl) benzene is usually 0.5 to 20 times, preferably 1 to 8 times, styrene polymerized using a carboxyl group-containing styrene / acrylic copolymer and / or its ammonium salt as an emulsifier. Acrylic copolymer is 0.5 to 30 times, preferably 1 to 10 times,
Used in the weight ratio range. [0008] The present invention is used as an emulsifier,
The carboxyl group-containing styrene-acrylic copolymer and / or its ammonium salt means that the monomer component is composed of styrene, (meth) acrylic acid, and (meth) acrylic acid ester and has a molecular weight of 2,000 to 100,000, preferably 5 to 100,000. Thousand to two
We are chosen from ten thousand. In the present invention, a method for producing a carboxyl group-containing styrene-acrylic copolymer and / or an ammonium salt thereof used in the present invention from the above-mentioned monomer component is a conventionally known method, for example, mixing monomer components in an arbitrary ratio. This is obtained by emulsifying this in an aqueous medium using an emulsifier, polymerizing using a polymerization initiator, and then neutralizing with ammonia. The styrene / acrylic copolymer obtained by polymerizing a carboxyl group-containing styrene / acrylic copolymer and / or its ammonium salt as an emulsifier used in the present invention is referred to as a carboxyl group-containing styrene / acrylic copolymer as an emulsifier. A styrene / acrylic copolymer obtained by polymerization using an union and / or an ammonium salt thereof, wherein the monomer component comprises styrene, (meth) acrylic acid, and (meth) acrylic acid ester, and has a molecular weight of usually 10 10,000 to 1,000,000, preferably 200,000 to 800,000 compounds. As the monomer component ratio, for example, styrene is 1 to 95% molar ratio (preferably 20 to 95%).
(80% molar ratio), (meth) acrylic acid is 1 to 50% molar ratio (preferably 10 to 40% molar ratio), (meth) acrylic acid ester is 1 to 95% molar ratio (preferably 20 to 8%).
0% molar ratio). Specific examples of the (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec -Butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, and the like. Particularly preferred are 2-ethylhexyl acrylate and the like. The styrene-acrylic copolymer containing a carboxyl group-containing styrene-acrylic copolymer and / or an ammonium salt thereof as an emulsifier used in the present invention can be obtained from the market. For example, trade name: Cybinol EK- 61 (manufactured by Seiden Chemical Co., Ltd.). Specific examples of the color-forming compound that can be used include:
Generally, any material may be used as long as it is used for pressure-sensitive recording paper or heat-sensitive recording paper, and is not particularly limited. Specific examples include, for example, fluoran compounds, triarylmethane compounds,
Examples include spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds. Specific examples of the fluoran compound include, for example, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl -N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3
-(N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-
Isobutylamino) -6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran,
3- (N-ethyl-N-hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6
-Methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6 Methyl-7-anilinofluoran, 3-
Diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7
-(P-fluoroanilino) fluoran, 3- [N-ethyl-N- (p-tolyl) amino] -6-methyl-7-
Anilinofluoran, 3-diethylamino-6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3 -Diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-7-
(3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro- 7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran,
3-diethylamino-7-octylfluoran, 3-
[N-ethyl-N- (p-tolyl) amino] -6-methyl-7-phenethylfluoran and the like. Specific examples of triarylmethane compounds include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis ( p
-Dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methyl Indole-3-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (2-Phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-
Yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide,
3,3- (2-phenylindol-3-yl) -5
Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like. Specific examples of spiro compounds include, for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, Propyl spirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6
-Nitro-8'-methoxyspiro (indoline-2,
2′-benzopyran) and the like are specific examples of diphenylmethane compounds such as N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-tri Chlorophenyl leuco auramine and the like are specific examples of the thiazine compound, for example, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue and the like. Specific examples of the lactam compound are, for example, rhodamine B anilinolactam, rhodamine B-p -Chloroanilinolactam and the like are specific examples of the fluorene compound, for example, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-dimethylaminophthalide, 3,6-bis ( Dimethylamino) fluorenespiro (9,3 ')-6'-pyrroli Nofutarido, 3-dimethylamino-6-diethylamino fluorene spiro (9,
3 ′)-6′-Pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination. As the color-developing compound, any compounds which are generally used for pressure-sensitive recording paper or heat-sensitive recording paper can be used. For example, α-naphthol, β-naphthol, p-octylphenol, 4-t- Octylphenol, p-
t-butylphenol, p-phenylphenol, 1,
1-bis (p-hydroxyphenyl) propane, 2,2
-Bis- (p-hydroxyphenyl) propane (alias:
Bisphenol A or BPA), 2,2-bis- (p-
(Hydroxyphenyl) butane, 1,1-bis- (p-hydroxyphenyl) cyclohexane, 4,4′-thiobisphenol, 4,4′-cyclo-hexylidenediphenol, 2,2′-bis- (2,5 -Dibromo-4-hydroxyphenyl) propane, 4,4'-isopropylidenebis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, 4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, methyl bis (4-hydroxyphenyl) acetate, bis (4-hydroxyphenyl)
Phenolic compounds such as butyl acetate and benzyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, 5-hydroxyisophthalate Pressure-sensitive recording paper such as ethyl acrylate, 3,5-di-t-butylsalicylic acid, aromatic carboxylic acid derivatives such as 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof; And color-developing compounds that can be used in combination with thermosensitive recording papers, but are not limited thereto. Specific examples of sensitizers (thermofusible compounds) that can be used in the present invention include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, and naphthalene derivatives. , Aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, etc., which are solid at room temperature and have a melting point of about 70 ° C. or more Can be used. Specific examples of waxes that can be used in combination include:
For example, wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, polyethylene oxide, etc., as specific examples of higher fatty acids, for example, stearic acid, behenic acid, etc., as specific examples of higher fatty acid amides For example, stearic acid amide,
Oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, and the like. Specific examples of the higher fatty acid anilide include, for example, stearic acid anilide, linoleic acid. Examples of the naphthalene derivative include anilide and the like, for example, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-benzyloxynaphthalene,
Specific examples of aromatic ethers such as hydroxynaphthoic acid phenyl ester include 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis (3-methylphenoxy) ethane, 1,2 -Screw (4-
Methoxyphenoxy) ethane, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1-phenoxy-2- (4
-Chlorophenoxy) ethane, 1-phenoxy-2-
Specific examples of the aromatic carboxylic acid derivative include (4-methoxyphenoxy) ethane and the like, for example, p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, terephthalic acid dibenzyl ester and the like are aromatic sulfones. Specific examples of the acid ester derivative include, for example, p-toluenesulfonic acid phenyl ester,
Phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate and the like are specific examples of carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate,
Dibenzyl oxalate, di (4-chlorobenzyl) oxalate, di (4-methylbenzyl) oxalate and the like are specific examples of biphenyl derivatives, for example, p-benzylbiphenyl, p-allyloxybiphenyl and the like. However, specific examples of the terphenyl derivative include, for example, m-terphenyl, and specific examples of the sulfone derivative include, for example, diphenyl sulfone. The amount of the sensitizer that can be used in combination is preferably in a range that does not impair the effects of the present invention, for example, a range that does not exceed the amount of 1,2-bis (phenoxymethyl) benzene. Specific examples of the binder that can be used in combination include, for example, methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, and sulfonic acid group-modified polyvinyl alcohol. , Polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer Water-soluble ones such as alkali salts of polyvinyl acetate, polyvinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, ethylene / acrylic acid copolymer, styrene / butadiene /
Examples include hydrophobic polymer emulsions such as acrylic acid-based copolymers and composite particles of colloidal silica and acrylic resin. Specific examples of the filler that can be used include, for example, calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, and polystyrene resin. And urea-formalin resins. Other additives include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head abrasion and sticking, and phenol derivatives for imparting an antioxidant or antiaging effect. UV absorbers such as benzophenone-based compounds and benzotriazole-based compounds, various surfactants, defoamers and the like are added as required. The heat-sensitive recording material of the present invention is prepared using the above-mentioned materials by, for example, the following method. That is, first, a color-forming compound, a color-developing compound, and 1,2-bis (phenoxymethyl) benzene are separately added to a ball mill, an attritor, a sand mill, and the like together with a binder or other additives as necessary by a conventional method. Crushed by disperser,
After dispersing (pulverizing and dispersing are usually performed by using water as a medium when performed by a wet method), mixing is performed, and a styrene / acrylate copolymer is further added to prepare a thermosensitive coloring layer coating solution.
A bar coater on a support such as paper, plastic sheet or synthetic paper so that the dry weight is usually 1-20 g / m ² ;
The heat-sensitive recording material of the present invention is obtained by drying with a blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight ratio). If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer (protective layer) may be provided on the thermosensitive coloring layer. The intermediate layer and the overcoat layer (protective layer) are pulverized and dispersed in the same manner as in the preparation of the thermosensitive coloring layer coating solution together with a binder or other additives as necessary, and then the intermediate layer coating solution or the overcoat layer (protective layer) Layer) After forming the coating solution, the coating solution is applied so that the dry weight is usually about 0.1 to 10 g / m ² . Usually, a colorless or pale-colored color-forming compound, a color-developing compound, 1,2-bis (phenoxymethyl) benzene, a styrene-acrylic copolymer containing a carboxyl group and / or styrene polymerized using an ammonium salt thereof as an emulsifier. The heat-sensitive recording material of the present invention containing an acrylic copolymer has higher sensitivity, less background fogging, and excellent storage stability as compared with conventionally known materials. EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight. Example 1 (Formation of thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 1 μm or less, and the solutions [A], [B], and [ C] was prepared. [A] solution: 3-dibutylamino-6-methyl-7-anilinofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: 4,4'-dihydroxydiphenylsulfone 25 parts 25% PVA aqueous solution 20 parts water 55 parts [C] liquid: 1,2-bis (phenoxymethyl) benzene 25 parts 25% PVA aqueous solution 20 parts water 55 parts Then, the mixture is mixed in the following ratio to prepare a thermosensitive coloring layer coating solution. Then, it was coated on a high-quality paper having a basis weight of 50 g / m ² so that the weight when dried was 8 g / m ^2, and dried to obtain a thermosensitive coloring layer. [A] liquid 16 parts [B] liquid 32 parts [C] liquid 40 parts 50% aqueous calcium carbonate dispersion 16 parts 40% carboxyl group-containing styrene-acrylic copolymer and / or its ammonium salt was polymerized as an emulsifier. Styrene / acrylic copolymer (average molecular weight about 50
10 parts of an emulsion containing a styrene / 2-ethylhexyl acrylate resin ratio of about 50:50) (formation of a protective layer). Further, a protective layer coating solution having the following composition ratio was dried on the thermosensitive coloring layer. Weighs 3 g / m
^The resultant was coated and dried to obtain a heat-sensitive recording material of the present invention having a protective layer. 40% styrene / acrylic acid ester copolymer emulsion 20 parts 5% aqueous bentonite dispersion 40 parts 30% zinc stearate aqueous dispersion 3 parts Example 2 40% carboxyl group-containing styrene acrylic of Example 1 Instead of an emulsion containing a styrene-acrylic copolymer (average molecular weight: about 500,000) obtained by polymerizing a copolymer and / or its ammonium salt as an emulsifier, 40
% Carboxyl group-containing styrene-acrylic copolymer and / or an ammonium salt thereof polymerized as an emulsifier (average molecular weight: about 300,000, styrene / 2-ethylhexyl acrylate resin ratio: about 7
0:30) was used to obtain a heat-sensitive recording material of the present invention having a protective layer in the same manner as in Example 1. Example 3 25% 3-dipentylamino-6 obtained by pulverization and dispersion in the same manner as in Example 1 in place of the solution [A] of Example 1
Using an aqueous dispersion of methyl-7-anilinofluoran,
In the same manner as in Example 1, a thermosensitive recording material of the present invention having a protective layer was obtained. Example 4 A 25% bis (3-allyl-4-hydroxyphenyl) sulfone aqueous dispersion obtained by pulverization and dispersion in the same manner as in Example 1 was used instead of the solution [B] of Example 1. Thus, a heat-sensitive recording material of the present invention having a protective layer was obtained in the same manner as in Example 1. Example 5 Instead of the solution [B] of Example 1, pulverization was carried out in the same manner as in Example 1.
Using a 25% aqueous dispersion of 4-hydroxy-4'-isopropoxydiphenylsulfone obtained by dispersion, a thermosensitive recording material of the present invention having a protective layer was obtained in the same manner as in Example 1. Table 1 shows the quality performance of the heat-sensitive recording material of the present invention obtained as described above. Table 1 Quality performance test Ground ¹⁾ Color density ²⁾ Heat resistance ³⁾ Water resistance ⁴⁾ Plasticizer resistance ⁵⁾ Example 1 0.05 1.57 1.57 1.34 1.46 Example 2 0.05 1.55 1.56 1.32 1.49 Example 3 0.04 1.57 1.55 1.32 1.48 Example 4 0.04 1.70 1.70 1.40 1.40 61 Example 5 0.04 1.62 1.61 1.32 1.50 1) Background: The uncolored portion of the sample was measured by a Macbeth reflection densitometer RD-914 (Macbeth reflection density). 2) Color density: Macbeth reflection density value of an image portion printed by a thermal printer (D-805P) manufactured by Ishida Corporation. 3) Heat resistance: 6 samples of color developed by the above printer
The Macbeth reflection density of the image portion after being left in a thermostat at 0 ° C. for 24 hours. 4) Water resistance: Macbeth reflection density of an image portion after immersing a sample colored with the above printer in tap water at room temperature for 24 hours. 5) Plasticizer resistance: P is applied to the sample colored with the above printer.
0.0294MP together with VC wrap film on both sides
(a) Macbeth reflection density of an image portion after standing at room temperature under a load of 300 g / cm ² for 24 hours. As is clear from the table, the heat-sensitive recording material of the present invention has excellent whiteness and color density of the background, and has excellent storage stability such as heat resistance, water resistance and plasticizer resistance. According to the present invention, a heat-sensitive recording material having high sensitivity, little background fog, and excellent storage stability was obtained.

Claims (1)

Claims: 1. A heat-sensitive coloring layer mainly comprising a colorless or pale-colored color-forming compound and a color-developing compound capable of coloring the color-forming compound when heated on a support. In the heat-sensitive recording material, the heat-sensitive coloring layer is formed of 1,2-bis (phenoxymethyl) benzene, a styrene-acrylic copolymer containing a carboxyl group and / or a styrene-acrylic copolymer obtained by polymerizing an ammonium salt thereof as an emulsifier, A heat-sensitive recording material comprising: