JPH07266710A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material enhanced in the plasticizer resistance, oil resistance and water resistance of a recording part immediately after printing and not causing the fog and rusty color development of a background part caused by a plasticizer or oil. CONSTITUTION:As a coupler allowing a leuco compd. to form a color, at least one compd. selected from bis-(3-allyl-4-hydroxyphenyl)sulfone, 4-hydroxy-4'- isopropoxydiphenylsulfone and 2,2-bis(4-hydroxyphenyl)sulfone is used and, as a storage stabilizer, 4-(2-methyl-glycidyloxy)-4'-benzyloxydiphenylsulfone is used and, as a reaction accelerator, a mercaptobenzimidazole derivative or a metal salt thereof is used.

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, and more particularly, to an improvement of a heat-sensitive recording material provided with a heat-sensitive color forming layer containing a color developer which develops a colorless or slightly pale leuco dye under heat, The present invention relates to a heat sensitive recording material having excellent plasticizer resistance, oil resistance and water resistance.

[0002]

2. Description of the Related Art A heat-sensitive recording method using a normally colorless or slightly light-colored leuco dye and a color developer that develops the color of the leuco dye when heated does not require a developing step and is easy to maintain hardware. Therefore, it is widely used for recording for facsimiles, scientific measuring instruments, CD / ATM, POS labels and the like.

Conventionally, a heat-sensitive recording material using a leuco dye has a drawback that the recording density is easily reduced by a plasticizer, oil, water or the like added to the film, or the recording is completely erased in a remarkable case. Was. In order to make up for this drawback, various leuco dyes, developers and storage stabilizers have been studied, and improvements such as providing a protective layer on the heat-sensitive recording layer have been proposed.

For example, a storage stabilizer is disclosed in Japanese Patent Laid-Open No. 4-1.
No. 79579 discloses 4- (2-methyl-glycidyloxy) -4'-benzyloxydiphenyl sulfone or 4- (4-methylbenzyloxy) -4'as a storage stabilizer in a recording layer and / or an intermediate layer. The use of glycidyl oxydiphenyl sulfone is disclosed.

Further, it is disclosed in JP-A-57-6792 that an imidazole derivative is used as a storage stabilizer in the heat-sensitive layer, and 2-mercaptobenzimidazole is used in the intermediate layer between the support and the heat-sensitive layer. JP-A-2-896
No. 82 publication.

Further, as a combination of a specific leuco dye, a developer and a storage stabilizer, JP-A-5-221141 discloses 3- (N, N-dibutyl) amino-6-methyl-7-phenylaminofluorane as a leuco dye. At least one selected from 4,4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone, and bis (3-allyl-4-hydroxyphenyl) sulfone is used as a color developer, and further as a storage stabilizer. -(2-Methyl-glycidyloxy) -4'-benzyloxydiphenyl sulfone is used, and it is disclosed in claim 2 that a protective layer containing a water-soluble polymer and a pigment is provided on the thermosensitive coloring layer. There is.

[0007]

However, even the methods disclosed above have drawbacks such as excellent plasticity and oil resistance but poor water resistance, and are not always satisfactory. In particular, when the plasticizer resistance test is conducted immediately after printing, there is a phenomenon that the plasticizer resistance is significantly inferior.

This phenomenon is considered to be due to the slow reaction between the leuco dye and the storage stabilizer 4- (2-methyl-glycidyloxy) -4'-benzyloxydiphenyl sulfone.

The present invention has been found out as a result of various studies, and the density of the recorded portion is not lowered by the plasticizer, oil, water, etc. contained in the film, etc. It is an object of the present invention to provide a heat-sensitive recording material which is free from fog and rust-like color development which occurs over time.

[0010]

In the present invention, the developer is bis- (3-allyl-4-hydroxyphenyl) sulfone, and
-Hydroxy-4'-isopropoxydiphenyl sulfone and 2,2-bis (4-hydroxyphenyl) sulfone are used, and 4- (2-methyl-glycidyloxy) -4'-benzyl is used as a storage stabilizer. It has been found that by using oxydiphenyl sulfone and further using a mercaptobenzimidazole derivative or a metal salt thereof as a reaction accelerator, an excellent thermosensitive recording medium without the above-mentioned defects can be obtained.

The proper use range of each component is 100 to 500 parts by weight, preferably 200 to 300 parts by weight, and 10 to 100 parts by weight of the storage stabilizer with respect to 100 parts by weight of the leuco compound. , Preferably 30 to 60 parts by weight, and 10 to 100 parts by weight as the reaction accelerator component,
It is preferably 30 to 60 parts by weight.

Examples of the mercaptobenzimidazole derivative or its metal salt include 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, and 2-mercaptomethylbenzimidazole.

The leuco compound used in the formation of heat-sensitive color may be a single compound or a mixture of two or more kinds, for example, triphenylmethane type, fluorane type, spiropyran type, phenothiazine type, auramine type, indole type. Examples include compounds such as nophthalide compounds. Specifically, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylphenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6- Dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5 , 7-dimethylfluorane, 3-N-methyl-N
-Isobutyl-6-methyl-7-anilinofluorane,
3-N-ethyl-N-isoamilou 6-methyl-7anilinofluorane, 3-dimethylamino-7-chlorofluorane, 3-diethylamino-7-fluorane,
3-dimethylamino-7,8-benzfluorane,
3-diethylamino-6-methyl-7-chlorofluorane, 3- (N-ethyl-N-p-tolyl) -6-methyl-7-alininofluorane, 3- (Np-tolylu N-ethylamino) -6-methyl-7- Alininofluorane, 3-Pyrrolidino 6-methyl-7-Alininofluorane, 2- {N-3'-trifluoromethylphenyl) aminofluorane,

2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloroalinino) fluorane, 3-diethylamino-7- (O-chloroalinino) fluorane, 3-dibutylamino-7- (o-chloroalinino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-ani Rinofluorane, 3-diethylamino-6-methyl-7-alininofluorane, 3-diethylamino-6-methyl-7
-(2 ', 4'-dimethylamino) fluorane, 3- (N, N-diethylamino) -5-methyl-7- (N,
N-dibenzylamino) fluorane,

Benzoyl leuco methylene blue, 6 '
-Chloro-8'-methoxy-benzoindolinopyrilospirane, 6'-bromo-3'-methoxy-benzoindolinopyrilospirane, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5 ' -Chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide,
3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2-methoxy-5'-methylphenyl)
Phthalide, 3- (2′-methoxy-4′-dimethylaminophenyl) -3- (2′-hydroxy-4′-chloro-5′-methylphenyl) phthalide,

3-morpholino 7- (N-propyl-trifluoromethylalinino) fluorane, 3-diethylamino-5-chloro-7- (N-benzyl-fluoromethylalinino) fluorane, 3-pyridino 7- (di-p-chlorophenyl) methyl Aminofluorane, 3-diethylamino-5-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-
Toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino -7-Piperidinofluorane,

2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluorane,
3-dibutylamino-6-methyl-7-alininofluorane, 3,6-bis (dimethylamino) fluorenspiro (9,3 ')-6'-dimethylaminophthalide,
3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2 -Ethoxypropyl) amino-6-methyl-7-alininofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-alininofluorane,
3-diethylamino-6-methyl-7-mesidino 4 ', 5'-benzofluorane, 3-N-propyl-N-methylamino-6-methyl-7-alininofluorane, etc. are used.

In the paint for forming the thermosensitive coloring layer,
Polymers used as binders include starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose and ethyl cellulose,
Polyvinyl alcohol, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutyl / maleic anhydride copolymer Water-soluble polymers such as combined alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, as well as polyvinyl acetate, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride, vinyl acetate copolymer, ethylene / acetic acid A water-based emulsion such as a vinyl copolymer, a styrene / butadiene copolymer, a latex such as a styrene / butadiene / acrylic copolymer, or the like is used.

In addition, in the coating material for forming the thermosensitive coloring layer, there are further added usual auxiliary components such as pigments, heat-fusible substances, lubricants, surfactants, fluorescent dyes and storage stabilizers. Needless to say, they can be used in combination, for example, calcium carbonate, silica, zinc oxide, titanium oxide,
Aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated inorganic fine particles such as calcium and silica, urea-formalin resin, styrene-methacryl copolymer, organic fine powder such as polystyrene resin Pigment,

Fatty acids such as stearic acid and behenic acid, stearic acid amide, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1 -Hydroxy-2 naphthoic acid phenyl ester, 1-Hydroxy-2 naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4
-Dibenzyloxoinaphthalene, 1,2-bis (phenoxy) ethane, 1,2- (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy)
Ethane, 1,4-bis (phenoxy) butane, 1,
4-bis (phenoxy) -2-butene, dibenzoylmethane, 1,4-bis (phenylthio) butane,
1,4-bis (phenylthio) -2-butene, 1,3
-Bis (2-vinyloxyethoxy) benzene, 1,
4-bis (2-vinyloxyethoxy) benzene, p
-(2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dizenzoyloxypropane, dibenzyldisulfide,
1,1-diphenylethane, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-fropropanol,
N-octadecylcarbonyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene,
A heat-fusible substance or the like is used.

The support used in the present invention is not particularly limited and includes, for example, high-quality paper, recycled paper, single-glossy paper, oil-resistant paper, coated paper, art paper, cast coated paper, lightly coated paper, resin laminated paper. , Polyolefin synthetic paper, synthetic fiber paper, synthetic resin film and the like can be appropriately used.

Further, in the heat-sensitive recording paper of the present invention, an inorganic pigment and an intermediate layer containing a binder as a main component are provided between the support and the heat-sensitive color forming layer, if necessary, and further on the heat-sensitive recording layer. An overcoat layer may be provided, and a back layer for curl adjustment and the like may be provided.

[Test Method 1] Regarding the test method of the plasticizer resistance, the obtained recording material was used with a TH-PMD simulator (manufactured by Okura Electric Co., Ltd.) and applied energy of 0.4 mj / dot.
Then, the printed recording material was immediately sandwiched between two or three layers of Mitsui Toatsu Chemical's Hilap KMA wrapped in a cylindrical container, and then further wound in two or three layers, and placed in a constant temperature bath at 40 ° C. The method of storing for 72 hours was used.

[Test Method 2] Regarding the test method for oil resistance,
A method was used in which castor oil was dropped on the recording portion and the background portion recorded under the above printing conditions immediately after printing and wiped off after 1 hour.

[Test Method 3] Regarding the water resistance test method,
A test method was used in which the recording portion and the background portion recorded under the above printing conditions were immersed in tap water for 120 hours immediately after printing.

[0025]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 [Preparation of heat-sensitive paint] Liquid A: 3-N-propyl-N-methylamino-6-methyl-7-alininofluorane 9 parts by weight Polybilyl alcohol: 12% aqueous solution 15 parts by weight Polystyrene ammonium acrylate: 20% Aqueous solution 0.7 parts by weight Water 30 parts by weight Solution B: Bis- (3-allyl-4-hydroxyphenyl) sulfone 20 parts by weight m-terphenyl 20 parts by weight Polyvinyl alcohol: 12% aqueous solution 50 parts by weight Polystyrene ammonium acrylate: 20% Aqueous solution 3 parts by weight Water 62.3 parts by weight Solution C: 4- (2-methyl-glycidyloxy) -4'-benzyloxydiphenylsulfone 5 parts by weight Polyvinyl alcohol: 12% aqueous solution 8 parts by weight Polystyrene ammonium acrylate: 20% aqueous solution 0.3 layer Parts Water 16.7 parts by weight D liquid 2-mercaptobenzimidazole 5 parts by weight Polyvinyl alcohol: 12% aqueous solution 8 parts by weight Ammonium polystyrene acrylate: 20% aqueous solution 0.3 parts by weight water 16.7 parts by weight or more Each of the liquids was separately dispersed with a sand grinder until the average particle diameter became 1 μm or less.

Solution E: Synthetic silica (Mizukasil P-527: manufactured by Mizusawa Chemical Co., Ltd.) 20 parts by weight Water 80 parts by weight Solution E was dispersed for 15 minutes using a homomixer. Solution A prepared above: 54.7 parts by weight, solution B: 155.3 parts by weight, solutions C and D: 30 parts by weight each and solution E: 10
0 parts by weight are mixed, and this mixture is mixed with zinc stearate (3
20 parts by weight of 0% dispersion liquid, 66.7 parts by weight of polyvinyl alcohol (12% aqueous solution), and 80 parts by weight of water were added to obtain a heat-sensitive paint. Heat-sensitive coating was applied on high-quality paper so that the coating amount after air-drying would be 5 g / m2, and further subjected to gloss treatment so that the Oken smoothness of the surface would be about 500 seconds. Got the body

Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2-mercaptobenzimidazole of the liquid D was changed to 2-mercaptomethylbenzimidazole.

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the 2-mercaptobenzimidazole of the D liquid was changed to the zinc salt of 2-mercaptobenzimidazole.

Example 4 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the bis (3-allyl-4-hydroxyphenyl) sulfone in the solution B was changed to 4-hydroxy-4'-isopropoxydiphenylsulfone. Got

Example 5 The same as Example 4 except that 3-dibutylamino-6-methyl-7-alininofluorane was used instead of 3-N-propyl-N-methylamino-6-methyl-7-alininofluorane in the liquid A. Similarly, a thermosensitive recording medium was obtained.

Example 6 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the bis (3-allyl-4-hydroxyphenyl) sulfone of the solution B was changed to 2,2-bis (4-hydroxy) sulfone. Obtained.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the D-liquid 2-mercaptobenzimidazole dispersion was not used.

Comparative Example 2 In the same manner as in Example 1, except that the liquid C 4- (2-methyl-glycidyloxy) -4'-benzyloxyphenyl sulfone was not used.
A thermosensitive recording medium was obtained.

Comparative Example 3 The procedure of Example 1 was repeated except that the dispersion liquid of 4- (2-methyl-glycidyloxy) -4′-benzyloxyphenyl sulfone solution C was not used.
A thermosensitive recording medium was obtained.

Comparative Example 4 Thermal recording was carried out in the same manner as in Example 1 except that the bis (3-allyl-4-hydroxyphenyl) sulfone of the liquid B was changed to 2,2-bis (4-hydroxyphenyl) propane. Got the body

Comparative Example 5 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the bis (3-allyl-4-hydroxyphenyl) sulfone of the liquid B was changed to benzyl p-hydroxybenzoate.

Comparative Example 6 The same procedure as in Example 1 was repeated except that the 1,2-, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane was used as the 2-mercaptobenzimidazole in the liquid D. A thermosensitive recording medium was obtained.

Comparative Example 7 In the same manner as in Example 1 except that the 4-mercaptobenzimidazole of the liquid D was 4,4′-butylidene-bis (6-t-butyl-m-cresol). A thermosensitive recording medium was obtained.

Comparative Example 8 In Example 1, the 2-mercaptobenzimidazole of the liquid D was replaced with 2,2′-methylenebis (4-methyl-6-t).
-Butylphenol) was obtained in the same manner as in Example 1 to obtain a thermosensitive recording medium.

Comparative Example 9 A 2-mercaptobenzimidazole dispersion liquid of the liquid D was coated on a support in advance so that the coating amount after drying was 1 g / m 2, and the heat-sensitive coating liquid used in Example 1 was used. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the liquid D was removed.

[Evaluation] The thermal recording material obtained above was subjected to the plasticizer resistance test, oil resistance test and water resistance test described above. The test results of each thermal recording material are shown in the table. Evaluation method Recording part ○: The recording part after the test is clearly legible. Δ: The recording portion after the test is discolored. X: The recorded part after the test is difficult to read. Background part ◯: There is little overburden on the background part after the test. Δ: The background part after the test is covered. X: The background part after the test is significantly covered.

[0043]

【table】

[0044]

As is apparent from the table, the heat-sensitive recording material of the present invention was excellent in storage stability of the recording portion in any test and had no background covering.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive coloring layer containing a colorless or slightly pale leuco dye and a developer which develops a color when contacted with the leuco compound. Bis- (3-allyl-4-hydroxyphenyl)
At least one selected from sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone and 2,2-bis (4-hydroxyphenyl) sulfone is used, and 4- (2-methyl-glycidyloxy) -4 is used as a storage stabilizer. A thermosensitive recording material characterized by using benzyloxydiphenyl sulfone and a mercaptobenzimidazole derivative or a metal salt thereof as a reaction accelerator.