JPH0624134A - Material for thermal recording - Google Patents

Abstract

PURPOSE:To prevent yellowing by containing one kind or more of phenol group antioxidants in a thermal recording layer comprising an aromatic isocyanate compound and an imino compound. CONSTITUTION:One kind or more selected from phenolic antioxidants shown in formulae I-V are contained. Where (k) in formulae represents the integer of 0<=k<=3, R1 in formulae II-IV 1-8C alkyl groups and R1 in formula I a not more than 2C alkyl group, XCOOY or XOY (where X: 1-8C alkyl chains and Y: 1-20C alkyl chains). All R2 represent the 1-8C alkyl groups, R3, in formula I the 1-8C alkyl groups, R3 in formula II and formula III 1-20C alkyl groups, XCOOY, XOY and XCOOYOZ (where X, Y, Z represent the I-8C alkyl chains) and R3 in formula V the 1-20C alkyl groups. 0<=n<=3 and 0<=m<=3 hold in (n) and (m) in formula I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material which is excellent in image storability and has less yellowing of the background.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support and a heat-sensitive recording layer containing an electron-donating colorless dye precursor and an electron-accepting developer as main components. By heating with a hot pen, a laser beam or the like, the colorless dye precursor and the developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-140
No. 39, etc. Such a heat-sensitive recording material has the advantages that recording can be obtained with a relatively simple device, that maintenance is easy, and that no noise is generated.
It is used in a wide range of fields such as measuring recorders, facsimiles, printers, computer terminals, labels and ticket vending machines.

A heat-sensitive recording material using such an electron-donating colorless dye precursor and an electron-accepting color developer has a good appearance, a good feel, a high coloring density, various coloring hues and the like. On the other hand, the heat-sensitive coloring part (recorded image part) comes into contact with plastic such as polyvinyl chloride and disappears due to plasticizers and additives contained in the plastic, or food It easily loses contact with chemicals contained in cosmetics and cosmetics, or easily discolors when exposed to sunlight for a short period of time, resulting in poor storage stability of records. Under the present circumstances, the improvement is strongly desired.

As a heat-sensitive recording material which reacts when two components are heated to obtain a recorded image with good storability,
For example, JP-A-58-38733 and JP-A-58-540
No. 85, JP-A-58-104959, and JP-A-58-1.
49388, JP-A-59-115887, JP-A-5
9-115888 and U.S. Pat. No. 45217.
No. 93 discloses a heat-sensitive recording material whose two components are an imino compound and an isocyanate compound.

However, the heat-sensitive recording materials comprising these isocyanate compounds and imino compounds are excellent in image storability, but the non-image area, that is, the background, is yellowed by exposure to fluorescent lamps or sunlight. There is a problem that it occurs.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material which is excellent in image storability and which does not cause yellowing on the background due to exposure to fluorescent lamps or sunlight.

[0007]

Means for Solving the Problems The present inventors have proposed that a thermosensitive recording layer composed of an aromatic isocyanate compound and an imino compound contains a phenolic antioxidant, so that the thermosensitive recording layer contains a phenolic antioxidant. It was discovered that yellowing could be significantly reduced, leading to the completion of the present invention.

That is, the present invention provides a heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing an aromatic isocyanate compound and an imino compound, wherein the heat-sensitive recording layer has the following general formulas (I) and (II): A heat-sensitive recording material containing at least one of phenolic antioxidants represented by (III), (IV) and (V).

[0009]

[Chemical 6]

[0010]

[Chemical 7]

[0011]

[Chemical 8]

[0012]

[Chemical 9]

[0013]

[Chemical 10]

Specific examples of the phenolic antioxidant in the present invention include 2,6-di-tert-butyl-4-methylphenol and n-octadecyl-3- (3,5-tert-
Butyl-4-hydroxyphenol) propionate,
2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2- [1- (2-hydroxy-3,5
-Tert-pentylphenyl) ethyl] -4,6-di-te
rt-Pentylphenyl acrylate, 4,4'-thiobis (3-methyl-6-tert-butylphenol), triethylene glycol-bis [3- (3-tert-butyl-
5-Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5
-Di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6
-(4-Hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, pentaerystyryl-
Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-
Diethylenebis [3- (3,5-di-tert-butyl-4]
-Hydroxyphenyl) propionate] and the like.

These phenolic antioxidants may be used alone or in admixture of two or more, and are 0.01 to 300 parts by weight, preferably 0.01 to 20 parts by weight, relative to 100 of the aromatic isocyanate compound. The purpose is achieved by using parts by weight. As a method for adding the phenolic antioxidant, the phenolic antioxidant and the aromatic isocyanate compound are separately pulverized individually according to the method for preparing a heat-sensitive recording material. A method in which an antioxidant and an aromatic isocyanate compound are mixed, and then finely pulverized by a wet or dry method using a ball mill, sand mill, attritor, or other various pulverizers, and a phenolic antioxidant and an isocyanate compound are heated and dissolved to homogenize them. After that, a method of cooling and finely pulverizing, a method of dissolving each compound in a solvent to homogenize and drying and then finely pulverizing, etc. are preferable, and preferably a jet mill after mixing a phenolic antioxidant and an isocyanate compound. It is preferable to use a method such as co-milling.

The thermal recording material will be described in detail below. The aromatic isocyanate compound used in the present invention refers to a colorless or light-colored aromatic isocyanate compound or heterocyclic isocyanate compound which is solid at room temperature, and for example, one or more of the following isocyanate compounds are used. 2,6-dichlorophenyl isocyanate, p-
Chlorophenyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-dimethylbenzene-4,6-diisocyanate, 1,4-dimethylbenzene-2,5-diisocyanate Nato, 1-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-2,5-diisocyanate, 1-ethoxybenzene-2,4-diisocyanate, 2,5-dimethoxybenzene-1, 4-diisocyanate, 2,5-diethoxybenzene-1,4-diisocyanate, 2,5-dibutoxybenzene-1,4-diisocyanate, azobenzene-4,4'-diisocyanate, diphenyl ether -4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diiso Annatto, naphthalene-2,6
-Diisocyanate, naphthalene-2,7-diisocyanate, 3,3'-dimethyl-biphenyl-4,4'-
Diisocyanate, 3,3'-dimethoxybiphenyl-
4,4'-diisocyanate, diphenylmethane-4,
4'-diisocyanate, diphenyldimethylmethane-
4,4'-diisocyanate, benzophenone-3,
3'-diisocyanate, fluorene-2,7-diisocyanate, anthraquinone-2,6-diisocyanate, 9-ethylcarbazole-3,6-diisocyanate, bilen-3,8-diisocyanate , Naphthalene-
1,3,7-triisocyanate, biphenyl-2,
4,4'-triisocyanate, 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine, 4,4', 4" -triisocyanato-triphenylamine, p-dimethylamino Phenyl isocyanate,
Examples include tris (4-phenylisocyanate) thiophosphate. These isocyanates may be used in the form of so-called block isocyanates, which are addition compounds with phenols, lantams, oximes, etc., if necessary, and may be used in the form of diisocyanates. , Diisocyanate dimers, for example, 1-methylbenzene-2,4-diisocyanate dimers, and trimer isocyanurates can also be used. If all of them are blocked, the effect of the present invention may not occur.

The imino compound used in the present invention has at least one imino group represented by the following chemical formula 11,
A compound represented by the general formula shown in Chemical Formula 12 below, which is a colorless or pale-colored compound that is solid at room temperature.

[0018]

[Chemical 11]

[0019]

[Chemical 12]

Specific examples are shown below. It is also possible to use two or more types of imino compounds in combination depending on the purpose. 3-iminoisoindoline-1-one, 3-imino-4,5,5
6,7-Tetrachloroisoindoline-1-one, 3-
Imino-4,5,6,7-tetrabromoisoindoline-1-one, 3-imino-4,5,6,7-tetrafluoroisoindoline-1-one, 3-imino-5,6-
Dichloroisoindoline-1-one, 3-imino-4,
5,7-Trichloro-6-methoxy-isoindoline-
1-one, 3-imino-4,5,7-trichloro-6-
Methylmercapto-isoindoline-1-one, 3-imino-6-nitroisoindoline-1-one, 3-imino-isoindoline-1-spiro-dioxolane, 1,
1-dimethoxy-3-imino-isoindoline, 1,1
-Diethoxy-3-imino-4,5,6,7-tetrachloroisoindoline, 1-ethoxy-3-imino-isoindoline, 1,3-diiminoisoindoline, 1,3
-Diimino-4,5,6,7-tetrachloroisoindoline, 1,3-Diimino-6-methoxyisoindoline, 1,3-Diimino-6-cyanoisoindoline,
1,3-Diimino-4,7-dithia-5,5,6,6-
Tetrahydroisoindoline, 7-amino-2,3-dimethyl-5-oxopyrrolo [3,4b] pyrazine, 7-
Amino-2,3-diphenyl-5-oxopyrrolo [3,3
4b] pyrazine, 1-iminonaphthalimide, 1-iminodiphenimide, 1-phenylimino-3-iminoisoindoline, 1- (3'-chlorophenylimino) -3-iminoisoindoline, 1- (2 ', 5 ′ -Dichlorophenylimino) -3-iminoisoindoline, 1
-(2 ', 4', 5'-Trichlorophenylimino) -3-iminoisoindoline, 1- (2'-cyano-4'-nitrophenylimino) -3-iminoisoindoline, 1-
(2'-chloro-5'-cyanophenylimino) -3-
Iminoisoindoline, 1- (2 ', 6'-dichloro-
4'-nitrophenylimino) -3-iminoisoindoline, 1- (2 ', 5'-dimethoxyphenylimino)
-3-iminoisoindoline, 1- (2 ', 5'-diethoxyphenylimino) -3-iminoisoindoline,
1- (2'-methyl-4'-nitrophenylimino)-
3-iminoisoindoline, 1- (5'-chloro-2 '
-Phenoxyphenylimino) -3-iminoisoindoline, 1- (4'-N, N-dimethylaminophenylimino) -3-iminoisoindoline, 1- (3'-
N, N-dimethylamino-4'-methoxyphenylimino) -3-iminoisoindoline, 1- (2'-methoxy-5'-N-phenylcarbamoylphenylimino)
-3-iminoisoindoline, 1- (2'-chloro-5 '
-Trifluoromethylphenylimino) -3-iminoisoindoline, 1- (5 ', 6'-dichlorobenzothiazolyl-2'-imino) -3-iminoisoindoline,
1- (6'-methylbenzothiazolyl-2'-imino)
-3-iminoisoindoline, 1- (4'-phenylaminophenylimino) -3-iminoisoindoline, 1
-(P-Phenylazophenylimino) -3-iminoisoindoline, 1- (naphthyl-1'-imino) -3-
Iminoisoindoline, 1- (anthraquinone-1'-
Imino) -3-iminoisoindoline, 1- (5′-chloroanthraquinone-1′-imino) -3-iminoisoindoline, 1- (N-ethylcarbazolyl-3′-imino) -3-imino Isoindoline, 1- (naphthoquinone-1′-imino) -3-iminoisoindoline, 1-
(Pyridyl-4'-imino) -3-iminoisoindoline, 1- (benzimidazolone-6'-imino) -3-iminoisoindoline, 1- (1'-methylbenzimidazolone-6'-imino) -3-iminoisoindoline,
1- (7'-chlorobenzimidazolone-5'-imino) -3-iminoisoindoline, 1- (benzimidazolyl-2'-imino) -3-iminoisoindoline,
1- (benzimidazolyl-2'-imino) -3-imino-4,5,6,7-tetrachloroisoindoline, 1
-(2 ', 4'-dinitrophenylhydrazone) -3-
Iminoisoindoline, 1- (indazolyl-3'-imino) -3-iminoisoindoline, 1- (indazolyl-3'-imino) -3-imino-4,5,6,7-tetrabromoisoindoline, 1 -(Indazolyl-3 '
-Imino) -3-imino-4,5,6,7-tetrafluoroisoindoline, 1- (benzimidazolyl-2 '
-Imino) -3-imino-4,7-dithiatetrahydroisoindoline, 1- (4 ', 5'-dicyanoimidazolyl-2'-imino) -3-imino-5,6-dimethyl-4,7- Pyradiisoindoline, 1- (cyanobenzoylmethylene) -3-iminoisoindoline, 1- (cyanocarbonamidomethylene) -3-iminoisoindoline, 1- (cyanocarbomethoxymethylene) -3-iminoisoindoline, 1 -(Cyanocarboethoxymethylene) -3-iminoisoindoline, 1- (cyano-N
-Phenylcarbamoylmethylene) -3-iminoisoindoline, 1- [cyano-N- (3'-methylphenyl) -carbamoylmethylene] -3-iminoisoindoline, 1- [cyano-N- (4'-chlorophenyl) −
Carbamoylmethylene] -3-iminoisoindoline,
1- [cyano-N- (4'-methoxyphenyl) -carbamoylmethylene] -3-iminoisoindoline, 1-
[Cyano-N- (3'-chloro-4'-methylphenyl) -carbamoylmethylene] -3-iminoisoindoline, 1- (cyano-p-nitrophenylmethylene)-
3-iminoisoindoline, 1- (dicyanomethylene)
-3-iminoisoindoline, 1- [cyano-1 ',
2 ', 4'-triazolyl- (3')-carbamoylmethylene] -3-iminoisoindoline, 1- [cyanothiazoyl- (2 ')-carbamoylmethylene] -3-iminoisoindoline, 1- [cyanobenzimidazolyl- (2 ')-carbamoylmethylene] -3-iminoisoindoline, 1- [cyanobenzothiazolyl- (2')
-Carbamoylmethylene] -3-iminoisoindoline, 1- [cyanobenzimidazolyl- (2 ')-methylene] -3-iminoisoindoline, 1- [cyanobenzimidazolyl- (2')-methylene] -3-imino −
4,5,6,7-tetrachloroisoindoline, 1-
[(Cyanobenzimidazolyl-2 ')-methylene]-
3-imino-5-methoxyisoindoline, 1-[(cyanobenzimidazolyl-2 ')-methylene] -3-imino-6-chloroisoindoline, 1-[(1'-phenyl-3'-methyl-5 -Oxo) -pyrazolidene-
4 ']-3-iminoisoindoline, 1-[(cyanobenzimidazolyl-2')-methylene] -3-imino-
4,7-dithiatetrahydroisoindoline, 1-
[(Cyanobenzimidazolyl-2 ')-methylene]-
3-imino-5,6-dimethyl-4,7-pyradiisoindoline, 1-[(1'-methyl-3'-n-butyl)
-Barbituric acid-5 ']-3-iminoisoindoline,
3-imino-1-sulfobenzoic acid imide, 3-imino-
1-sulfo-6-chlorobenzoic acid imide, 3-imino-
1-sulfo-5,6-dichlorobenzoic acid imide, 3-imino-1-sulfo-4,5,6,7-tetrachlorobenzoic acid imide, 3-imino-1-sulfo-4,5,6,7
-Tetrabromobenzoic acid imide, 3-imino-1-sulfo-4,5,6,7-tetrafluorobenzoic acid imide,
3-imino-1-sulfo-6-nitrobenzoic acid imide,
3-imino-1-sulfo-6-methoxybenzoic acid imide, 3-imino-1-sulfo-4,5,7-trichloro-6-methylmercaptobenzoic acid imide, 3-imino-
1-sulfonaphthoic acid imide, 3-imino-1-sulfo-5-bromonaphthoic acid imide, 3-imino-2-methyl-4,5,6,7-tetrachloroisoindoline-1
-There is an on.

The heat-sensitive recording material according to the present invention is, as described above, provided with a heat-sensitive recording layer for coloring by heating on a support. Paper is mainly used as the support, but in addition to paper, various non-woven fabrics, synthetic resin films, laminated papers, synthetic papers, metal foils, etc., or composite sheets in which these are combined are arbitrarily used according to the purpose. You can The thermal recording layer may have a single layer structure or a multi-layer structure. In the case of multiple layers, an intermediate layer may be interposed between each layer. Further, a protective layer may be provided on this layer. This recording layer can be obtained by mixing the respective aqueous dispersions obtained by finely pulverizing the respective color-forming components, the binder, etc., and coating and drying on a support. In this case, for example, each color-forming component may be contained in one layer to form a multilayer structure.

The thermosensitive recording material according to the present invention may contain a heat-fusible substance in order to improve its sensitivity. Those having a melting point of 60 ° C. to 180 ° C. are preferable, and those having a melting point of 80 ° C. to 140 ° C. are particularly preferable. For example, benzyl p-benzyloxybenzoate, stearic acid amide, palmitic acid amide, N-methylol stearic acid amide, β-naphthyl benzyl ether, N-stearyl urea, N, N′-distearyl urea, β-naphthoic acid phenyl Ester, 1-hydroxy-2-naphthoic acid phenyl ester, β-naphthol (p-methylbenzyl) ether, 1,4-dimethoxynaphthalene, 1-methoxy-4-benzyloxynaphthalene, N-stearoylurea, 4-benzylbiphenyl , 1,2-di (m-methylphenoxy) ethane, 1-
Phenoxy-2- (4-chlorophenoxy) ethane,
1,4-butanediol phenyl ether, dimethyl terephthalate, etc. are mentioned.

The above-mentioned heat-fusible substances may be used alone or as a mixture, and in order to obtain a sufficient thermal response, 10 to 300 per 100 parts by weight of the aromatic isocyanate compound is used. It is preferable to use parts by weight, and further,
It is more preferable to use 20 to 250 parts by weight. Further, the heat-sensitive recording material of the present invention may contain an aniline derivative having at least one amino group, and is more effective in preventing background fog.

These compounds include methyl p-aminobenzoate, ethyl p-aminobenzoate, n-propyl p-aminobenzoate and p-aminobenzoic acid-iso-.
Propyl, butyl p-aminobenzoate, dodecyl P-aminobenzoate, benzyl p-aminobenzoate, o-aminobenzophenone, m-aminoacetophenone, p-aminoacetophenone, m-aminobenzamide, o-aminobenzamide, p- Aminobenzamide, p-amino-N-methylbenzamide, 3-amino-4-methylbenzamide, 3-amino-4-methoxybenzamide, 3-amino-4-chlorobenzamide, p- (N-
Phenylcarbamoyl) aniline, p- [N- (4-chlorophenyl) carbamoyl] aniline, p- [N-
(4-Aminophenyl) carbamoyl] aniline, 2-
Methoxy-5- (N-phenylcarbamoyl) aniline, 2-methoxy-5- [N- (2'-methyl-3'-
Chlorophenyl) carbamoyl] aniline, 2-methoxy-5- [N- (2'-chlorophenyl) carbamoyl] aniline, 5-acetylamino-2-methoxyaniline, 4-acetylaminoaniline, 4- (N-methyl-N-). Acetylamino) aniline, 2,5-diethoxy-4- (N-benzoylamino) aniline, 2,5-dimethoxy-4- (N-benzoylamino) aniline, 2
-Methoxy-4- (N-benzoylamino) -5-methylaniline, 4-sulfamoylaniline, 3-sulfamoylaniline, 2- (N-ethyl-N-phenylaminosulfonyl) aniline, 4-dimethylamino Sulfonylaniline, 4-diethylaminosulfonylaniline, sulfathiazole, 4-aminodiphenylsulfone, 2-chloro-5-N-phenylsulfamoylaniline, 2-methoxy-5-N, N-diethylsulfamoylaniline, 2 , 5-Dimethoxy-4-N-phenylsulfamoylaniline, 2-methoxy-5-benzylsulfonylaniline, 2-phenoxysulfonylaniline, 2- (2'-chlorophenoxy) sulfonylaniline, 3-anilinosulfonyl-4. -Methylaniline, bis [4- (m-amido Phenoxy) phenyl] sulfone, bis [4-(p-aminophenoxy) phenyl] sulfone, bis [3-methyl-4-(p-aminophenoxy) phenyl] sulfone, 3,3'-dimethoxy-4,
4'-diaminobiphenyl, 3,3'-dimethyl-4,
4'-diaminobiphenyl, 2,2'-dichloro-4,
4'-diamino-5,5'-dimethoxybiphenyl,
2,2 ', 5,5'-tetrachloro-4,4'-diaminobiphenyl, ortho-tolidine sulfone, 2,4'-
Diaminobiphenyl, 2,2'-diaminobiphenyl,
4,4'-diaminobiphenyl, 2,2'-dichloro-
4,4'-diaminobiphenyl, 3,3'-dichloro-
4,4'-diaminobiphenyl, 2,2'-dimethyl-
4,4'-diaminobiphenyl, 4,4'-thiodianiline, 2,2 'dithiodianiline, 4,4'-dithiodianiline, 4,4'-diaminodiphenyl ether, 3,
3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, bis (3-amino-4-chlorophenyl) sulfone, bis (3,4-diaminophenyl) ) Sulfone, bis (4-aminophenyl) sulfone, bis (3-aminophenyl)
Sulfone, 3,4'-diaminodiphenyl sulfone,
3,3'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 4,4'diamino-2,2'-dimethyldibenzyl, 4,4'-diamino-3,3'-dichlorodiphenylmethane, 3,3 ′ -Diaminobenzophenone, 4,4′-diaminobenzophenone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4
-Aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis (4-aminophenoxyphenyl) propane, 4,4 ' -Bis (4-aminophenoxy) diphenyl, 3,3 ', 4,4'-tetraaminodiphenyl ether, 3,3', 4,4'-tetraaminodiphenyl sulfone, 3,3'4,4'-tetraamino Examples thereof include benzophenone.

The binder used in the heat-sensitive recording material of the present invention includes starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, styrene-maleic anhydride copolymer, Water-soluble binder such as ethylene-maleic anhydride copolymer, styrene-butadiene copolymer,
Examples include latex-based water-insoluble binders such as acrylonitrile-butadiene copolymer and methyl acrylate-butadiene copolymer.

Further, in the heat-sensitive recording layer, pigments such as diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and others. , Higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearamide, and castor wax for the purpose of preventing head wear and sticking, and dioctylsulfosuccinic acid. A dispersant such as sodium acid salt, a benzophenone-based or benzotriazole-based ultraviolet absorber, a surfactant, a fluorescent dye, and the like may be contained.

Further, a leuco dye or the like may be added for the purpose of adjusting the color tone of the developed color.

[0028]

The present invention will be described in more detail with reference to the following examples.

[0029]

Example 1 2 g of 1,3-diimino-4,5,6,7, -tetrachloroisoindoline was mixed with 8 g of a 2.5% by weight aqueous solution of polyvinyl alcohol in a paint shaker.
After pulverizing for an hour, 2.5 g of a 15% by weight polyvinyl alcohol aqueous solution was added and pulverized for 15 minutes to obtain an aqueous dispersion.
Separately, 2 g of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine was added to 0.01 g of 2,6-di-tert-butyl-4-methylphenol or 0.
Mix 05g or 0.1g or 0.2g, 2.
A 5 wt% polyvinyl alcohol aqueous solution (4 g) and a 31 wt% ethanol aqueous solution (4 g) were pulverized with a paint shaker for 4 hours, and a 15 wt% polyvinyl alcohol aqueous solution (2.5 g) was added and pulverized for 15 minutes to obtain a dispersion liquid.
To 0.75 g of 1,3-diimino-4,5,6,7-tetrachloroisoindoline aqueous dispersion was added 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine aqueous dispersion. Add .50g and add 20 more calcium carbonate
2.5 g by weight aqueous dispersion, 1.0 g of 20% by weight aqueous 2-benzyloxynaphthalene dispersion, 2-methoxy-3
1.0 g of a 20% by weight aqueous dispersion of -N, N-diethylsulfamoylaniline was added and sufficiently stirred to obtain a coating liquid. This coating solution was coated on a base paper so that a coating amount of 1.03 g / m ² was obtained as a solid content, dried and then treated with a super calendar to obtain a heat-sensitive recording material.

This heat-sensitive recording material was irradiated with sunlight through a window glass for 4 days. The degree of yellowing is visually observed and
(Almost no discoloration), B (discolored compared to unirradiated thermosensitive recording material), C (discolored not compared to unirradiated thermosensitive recording material). ), D
(It is considerably discolored.), E (It is strongly yellowed.)
It was evaluated by Table 1 and shown in Table 1.

[0031]

EXAMPLE 2 2 g of 1,3-diimino-4,5,6,7-tetrachloroisoindoline was pulverized for 4 hours with a paint shaker together with 8 g of a 2.5 wt% polyvinyl alcohol aqueous solution, and further a 15 wt% polyvinyl alcohol aqueous solution. 2.5 g was added and pulverized for 15 minutes to obtain an aqueous dispersion. Separately, 2 g of 4,4 ′, 4 ″ -triisocyanato-2,5-dimethoxytriphenylamine was ground with a paint shaker for 4 hours together with 4 g of a 2.5 wt% aqueous solution of polyvinyl alcohol and 4 g of a 31 wt% aqueous solution of ethanol, and further 15 2.5 g of a weight% aqueous polyvinyl alcohol solution was added and the mixture was pulverized for 15 minutes to obtain a dispersion liquid, and 2 g of 2,6-di-tert-butyl-4-methylphenol was prepared separately.
Was pulverized with 4 g of a 2.5 wt% aqueous solution of polyvinyl alcohol and 4 g of a 31 wt% aqueous solution of ethanol for 4 hours with a paint shaker to obtain an aqueous dispersion. 5 g of this dispersion
Was added to the above 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine dispersion to give a mixed dispersion. 1,3-Diimino-4,5,6,7-tetra 0.50 g of the mixed dispersion was added to 0.75 g of the chloroisoindoline aqueous dispersion, and 2.5 g of a 20% by weight aqueous dispersion of calcium carbonate and 20 g of 2-benzyloxynaphthalene were added.
1.0 g of a weight% aqueous dispersion, 2-methoxy-3-N, N
-1.0 g of a 20% by weight aqueous dispersion of diethylsulfamoylaniline was added and sufficiently stirred to obtain a coating liquid. This coating solution was coated on a base paper so that a coating amount of 1.03 g / m ² was obtained as a solid content, dried and then treated with a super calendar to obtain a heat-sensitive recording material. Using this thermosensitive recording material, a yellowing test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

[0032]

Example 3 2 g of 1,3-diimino-4,5,6,7-tetrachloroisoindoline was pulverized for 4 hours with a paint shaker together with 8 g of a 2.5 wt% polyvinyl alcohol aqueous solution, and further a 15 wt% polyvinyl alcohol aqueous solution. 2.5 g was added and pulverized for 15 minutes to obtain an aqueous dispersion. Separately, 2 kg of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine was mixed with 0.1 kg of 2,6-di-tert-butyl-4-methylphenol to prepare a jet mill STJ- manufactured by Seishin Enterprise. 200, the average particle size is 1.
2.5% by weight of 2.1 g crushed to 4 μm
The mixture was pulverized with a paint shaker for 10 minutes together with 4 g of an aqueous polyvinyl alcohol solution and 4 g of an 31% by weight aqueous ethanol solution, and 2.5 g of a 15% by weight aqueous polyvinyl alcohol solution was added and ultrasonically dispersed for 15 minutes to obtain a dispersion liquid. 1,3-Diimino-4,5,6,7-tetrachloroisoindoline aqueous dispersion 0.75 g 4,4 ', 4 "-
0.5 g of an aqueous dispersion of triisocyanato-2,5-dimethoxytriphenylamine and 2,6-di-tert-butyl-4-methylphenol was added, and 2 parts of calcium carbonate was added.
2.5 g of 0 wt% aqueous dispersion, 1.0 g of 20 wt% aqueous dispersion of 2-naphthylbenzyl ether, 2-methoxy-
1.0 g of a 20% by weight aqueous dispersion of 3-N, N-diethylsulfamoylaniline was added and sufficiently stirred to obtain a coating liquid.
This coating solution was coated on a base paper so as to obtain a coating amount of 1.03 / m ² in solid content, dried and then treated with a super calendar to obtain a heat-sensitive recording material. Using this heat-sensitive recording material, a yellowing test was performed in the same manner as in Example 1, and the results are shown in Table 1.

[0033]

EXAMPLE 4 2 g of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine of Example 1 and 2,6-di-tert-butyl-4-methylphenol.
Instead of 1 g of the mixture, 2 g of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine and 2,6-di-tert-butyl-4-methylphenol.
A heat-sensitive recording material was obtained in the same manner as in Example except that 1 g of the mixture was dissolved in 20 ml of toluene and then dried. Using this thermosensitive recording material, a yellowing test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

[0034]

Example 5 2,6-di-tert-butyl-4 of Example 1
-N-octadecyl-3-instead of methylphenol
(3,5-di-tert-butyl-4-hydroxyphenol) propionate or 2,2'-methylenebis (4-methyl-6-tert-butylphenol) or 4,4'-thiobis (3-methyl-6-tert) -Butylphenol) or triethyleneglycol-bis [3
-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] or 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 0.1 g of hydroxyphenyl) propionate was used. A yellowing test was conducted using this heat-sensitive recording material, and the results are shown in Table 1.

[0035]

Comparative Example 1 2.0 g of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine of Example 1
2,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine in place of a mixture of 0.1 g of 2,6-di-tert-butyl-4-methylphenol.
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 0 g was used. Using this thermosensitive recording material, a yellowing test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

[0036]

[Comparative Example 2] 4, which was crushed by the jet mill of Example 3
4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine 2 g and 2,6-di-tert-butyl-4
-Jet milled 4,4 ', 4 "-triisocyanato-2,5- instead of 0.1 g of methylphenol
A heat-sensitive recording material was obtained in the same manner as in Example 3 except that 2 g of dimethoxytriphenylamine was used. Using this thermosensitive recording material, a yellowing test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

[0037]

COMPARATIVE EXAMPLE 3 2 g of 4,4 ', 4 "-triisocyanato-2,5-dimethoxytriphenylamine of Example 4 and 2,6-di-tert-butyl-4-methylphenol.
1 g of the mixture was dissolved in 20 ml of toluene and dried to give 4,4 ', 4 "-triisocyanato-
20 ml of 2,5-dimethoxytriphenylamine 2 g
A heat-sensitive recording material was obtained in the same manner as in Example 4 except that a person who had dissolved in toluene and dried was used. Using this thermosensitive recording material, a yellowing test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

[0038]

[Table 1]

[0039]

EFFECT OF THE INVENTION It is possible to obtain a heat-sensitive recording material which is excellent in image storability and has little background yellowing.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a heat-sensitive recording layer containing an aromatic isocyanate compound and an imino compound and a support, wherein the heat-sensitive recording layer has the following general formula (I):
A heat-sensitive recording material containing at least one of phenolic antioxidants represented by (II), (III), (IV) and (V). [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] [Chemical 5]