JPH0939410A - Manufacture of heat-sensitive coating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a heat-sensitive coating liquid for obtaining a heat-sensitive recording material, the ground of which is excellent in lappingly covering resistance and in image keeping quality. SOLUTION: At the manufacturing of a heat-sensitive coating liquid containing an aromatic isocyanante compound and an imino compound, which develops color through the reaction with the aromatic isocyanate compound, the dispersion of the isocyanate compound is heat-treated under the condition, in which the relationship between temperature Y ( deg.C) and time X (day) satisfies the inequalities: 80-3X>Y>25/X under 15>=X>0 and 37.75-X/20>Y>25/X under 120>=X>=15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-sensitive coating liquid capable of forming a heat-sensitive recording material having excellent resistance to wrapping on the background and image storability.

[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, laser light 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 it is easy to maintain, and that it does not generate noise, and it is a terminal for measuring recorders, facsimiles, printers, and computer terminals. It is used in a wide range of fields such as machines, labels, ticket vending machines, and other 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.
While it has excellent properties such as good feel, high color density, and various color hues, the thermosensitive color part (recorded image part) is in contact with plastic such as polyvinyl chloride to form plastic. Preservation of records such as disappearance due to plasticizers and additives contained in the product, easy disappearance upon contact with chemicals contained in foods and cosmetics, or fading easily after exposure to sunlight for a short time Is inferior, and due to this drawback, the application is subject to certain restrictions, and its improvement is strongly desired.

Further, in recent years, a high-speed printing apparatus capable of printing in a short time has been developed, and it has excellent thermal response suitable for it.
There has been a demand for a highly sensitive heat-sensitive recording material capable of obtaining a sufficiently colored image even at low energy. Examples of the heat-sensitive recording material capable of obtaining a recorded image having good storability include JP-A-58-38733, JP-A-58-54085, JP-A-58-104959, and JP-A-58-58.
149388, JP-A-59-115888, JP-A-59-115888, and U.S. Pat. No. 4,521,793 describe a heat-sensitive agent mainly containing an aromatic isocyanate and an imino compound. A recording material comprising a combination of heat sensitive agents is disclosed.

However, these thermal recording materials are
The recorded image was excellent in storability, but the sensitivity and (thermal response) were poor. For the purpose of improving the sensitivity of this heat-sensitive recording material, JP-A-59-135186 discloses a heat-sensitive recording material comprising an aromatic isocyanate, an imino compound, a leuco dye and an acidic substance which reacts with the leuco dye to develop a color. However, there is a problem in practical use because the heat resistance of the background and the resistance to wrapping are poor. In addition to these, JP-A-60
In JP-A-262686, JP-A-2-103180, and JP-A-4-232777, 3 of aromatic isocyanate, imino compound and specific fluoran compound are disclosed.
Although a heat-sensitive recording material comprising the components has been disclosed, the improvement in sensitivity is clearly recognized, but the lap fog resistance is inferior and is not practically sufficient.

Japanese Patent Publication No. 5-076918 discloses a heat-sensitive recording in which the storability of the background is improved by containing an aniline derivative as a third component in a combination of a color former composed of an aromatic isocyanate compound and an imino compound. Although a material is disclosed, in a heat-sensitive recording material containing a leuco dye and an acidic substance that develops a color by reacting with the leuco dye in addition to these three components, a physical property balance between heat resistance of the background and resistance to lap covering is provided. Is bad and there is a problem in practical use.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a heat-sensitive coating liquid for obtaining a heat-sensitive recording material which has excellent resistance to wrapping on the background and excellent image storability. .

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied in order to obtain a heat-sensitive recording material having excellent heat resistance of the background and resistance to wrapping, and excellent image storability. The present invention has been completed by finding a method for producing a heat-sensitive coating liquid by subjecting a dispersion liquid of a compound to heat treatment under specific conditions. By using this heat-sensitive coating liquid, it is possible to obtain a heat-sensitive recording material which is excellent in the resistance to wrapping resistance of the sensitive background and in the image storability.

That is, the present invention is as follows. At the time of producing a heat-sensitive coating liquid containing an aromatic compound and an imino compound capable of forming a color by reacting with the aromatic isocyanate compound, a dispersion of the isocyanate compound, before mixing with the dispersion of the imino compound. A method for producing a heat-sensitive coating liquid, which comprises heat-treating under conditions satisfying the following formula. The relationship between temperature (Y ° C) and time (X days) is 80-3X>Y> 25 / X (15 ≧ X> 0) 35.75-X / 20>Y> 25 / X (120 ≧ X ≧ 1)
5) The aromatic isocyanate compound used in the present invention refers to a colorless or light-colored aromatic isocyanate compound or a heterocyclic isocyanate compound which is solid at room temperature, and for example, one or more of the following isocyanate compounds are used. To be

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, 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-diisocyanate, 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-di Isocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-
2,4,4'-triisocyanate, 4,4 ', 4 "-
Triisocyanato-2,5-dimethoxytriphenylamine, 4,4 ′, 4 ″ -triisocyanatotriphenylamine, p-dimethylaminophenylisocyanate,
Examples include tris (4-phenylisocyanate) thiophosphate. If desired, these isocyanates may be used in the form of so-called block isocyanates, which are addition compounds with phenols, lactams, oximes, etc., and dimers of diisocyanate, for example, 1- It may be used in the form of isocyanurate, which is a dimer and trimer of methylbenzene-2,4-diisocyanate, or may be used as a polyisocyanate adducted with various polyols. is there.

Of these, the triphenylamine derivative isocyanate is particularly preferable, and 4,4 ',
4 ″ -triisocyanate-2,5-dimethoxytriphenylamine is preferred. The method for producing the heat-sensitive coating solution of the present invention is carried out as follows. 1 of these aromatic isocyanates
One or more species are preliminarily dispersed in an aqueous solution containing a compound having a dispersive ability such as a water-soluble polymer and a surfactant, and this preliminary dispersion is optionally subjected to a paint shaker, a ball mill, a vibrating ball mill, It is crushed by a crusher such as an attritor, sand mill, dyno mill or colloid mill to prepare a dispersion liquid of aromatic isocyanate. When the particle size of the heat-sensitive agent is small, it is sufficient to disperse it with a stirrer such as Corless. Further, alcohol may be added at the time of dispersion or pulverization as is conventionally known.

The average particle size of the dispersion after pulverization is 0.7 to
It is preferably 3.0μ. After dispersion, the temperature (Y
The relationship between (C) and time (X days) is 80-3 X>Y> 25 / X (15 ≧ X> 0) 35.75-X / 20>Y> 25 / X (120 ≧ X ≧ 1)
Heat treatment is performed in a range satisfying 5). If it deviates from this range, the wrap resistance of the background is inferior and the storage stability is not sufficiently exhibited. The imino compound used in the present invention is
Having at least one imino group represented by the following chemical formula 1,
A compound represented by the general formula shown in Chemical Formula 2 below, which is a colorless or light-colored compound that is solid at room temperature. An imino compound is also prepared in a dispersion and used. Specific examples are shown below. It is also possible to use two or more types of imino compounds in combination depending on the purpose.

[0013]

Embedded image

[0014]

Embedded image

(Φ is an aromatic compound residue capable of forming a conjugated system with adjacent C = N) 3-iminoisoindoline-1-one, 3-imino-
4,5,6,7-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-methyl Mercapto-isoindoline-1-one, 3-imino-6-nitroisoindoline-1-one, 3-imino-isoindoline-1-spiro-dioxolan, 1,1-dimethoxy-3-imino-isoindoline, , 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 [3,4b] 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,
-(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-iminoiso Indoline, 1- (N-ethylcarbazolyl-3'-imino) -3-iminoisoindoline, 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-imi111inoisoindoline, 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- (benz Imidazolyl-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 imide, 3-imino-1-sulfo-6-chlorobenzoic imide, 3-imino-1-sulfo-5,6-dichlorobenzoic imide, 3-imino-1-sulfo-4,
5,6,7-tetrachlorobenzoic imide, 3-imino-1-sulfo-4,5,6,7-tetrabromobenzoic imide, 3-imino-1-sulfo-4,5,6,7-tetra Fluorobenzoimide, 3-imino-1-sulfo-6-nitrobenzoimide, 3-imino-1-sulfo-6-methoxybenzoimide, 3-imino-1-sulfo-4,5,7-trichloro -6-methylmercaptobenzoic imide, 3-imino-1-sulfonaphthoic imide, 3-imino-1-sulfo-5-bromonaphthoic imide, 3-imino-2-methyl-4,5,6,7-tetra Chloroisoindoline-1-one and the like.

Of these, iminoisoindoline derivatives are particularly preferable, and 1,3-diimino-4,
5,6,7-tetrachloroisoindoline, 3-imino-4,5,6,7-tetrachloroisoindoline-1-
On, 1,3-diimino-4,5,6,7-tetrabromoisoindoline is preferred. In the present invention, the heat-sensitive recording layer may contain a leuco dye and an acidic substance that reacts with the leuco dye to develop a color as a color former, but the leuco dye used and the acidic substance that develops a color when reacted with the leuco dye are used. Is a compound already known as a color former used in a heat-sensitive recording material and is not particularly limited, but examples thereof include the following.

Specific examples of the leuco dye are shown below. (1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- ( p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-
Yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-
p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

(2) Diphenylmethane compound 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-halophenylleuco auramine, N-2,4,5-trichlorophenyl leuco auramine and the like. (3) Xanthene compounds rhodamine B anilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7 -Phenylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-diethylamino- 7
-(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6 Methyl-7-phenethylfluoran, 3-diethylamino-7- (4-nitroanilino) fluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6 Methyl-7-anilinofluoran, 3
-(N-ethyl-N-tetrahydrofuryl) amino-6
-Methyl-7-anilinofluoran, and the like.

(4) Thiazine-based compounds Benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, and the like. (5) Spiro compound 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) Spiropyran, 3-propylspirobenzopyran, etc.

These leuco dyes may be used alone or in combination. Next, specific examples of acidic substances will be shown. Generally, an electron-accepting substance used for thermal paper is used, and a phenol derivative, an aromatic carboxylic acid derivative or a metal compound thereof, an N, N-diarylthiourea derivative and the like are particularly preferable. Particularly preferred is a phenol derivative, specifically, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl). ) Pentane, 2,2-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl)
Butyl acetate, bis (4-hydroxyphenyl) benzyl acetate, bis (4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, 4
-Hydroxyphenyl-4'-methylphenyl sulfone, 3-chloro-4-hydroxyphenyl-4'-methylphenyl sulfone, 3,4-dihydroxyphenyl-
4'-methylphenyl sulfone, 4-isopropylphenyl-4'-hydroxyphenyl sulfone, 4-isopropyloxyphenyl-4'-hydroxyphenyl sulfone, bis (2-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl- 4'-benzyloxyphenyl sulfone, 4-isopropylphenyl-4 '
-Hydroxyphenyl sulfone, bis (2-methyl-3)
-Tert. -Butyl-4-hydroxyphenyl) sulfide, ethyl 4-hydroxybenzoate. Benzyl 4-hydroxybenzoate. 4-hydroxybenzoic acid (4'-
(Chlorobenzyl), 1,2-bis (4'-hydroxybenzoate) ethyl, 1,5-bis (4'-hydroxybenzoate) benzyl, 1,6bis (4'-hydroxybenzoate) hexyl, 3- Examples thereof include dimethyl hydroxyphthalate, stearyl gallate, and lauryl gallate.

Among these, particularly when 2,2-bis (4-hydroxyphenyl) propane is used, the balance between heat resistance and lap fog resistance is remarkably improved. The acidic substances may be used alone or as a mixture, and in order to obtain a sufficient thermal response, 50 to 2 with respect to the leuco dye.
It is preferably 50% by weight. The weight ratio of the color former system consisting of the leuco dye and the acidic substance and the color former system consisting of the imino compound and the aromatic isocyanate compound is 1: 9 to 9: 1 in order to obtain sufficient color developing sensitivity. It is preferable, and more preferably, it is 1: 3 to 3: 1. Next, the heat-sensitive recording layer of the present invention may contain an amine compound, but the amine compound used in the present invention is a room temperature solid having at least one primary or secondary amino group. It is a colorless or pale substance.

Specific examples of these amine compounds include cetylamine, stearylamine, beef tallow-derived primary amine, beef tallow-derived secondary amine, beef tallow-derived primary diamine, coconut oil-derived primary amine, coconut oil-derived secondary amine. , Aliphatic amines such as coconut oil-derived primary diamine, methyl p-aminobenzoate, ethyl p-aminobenzoate, n-propyl p-aminobenzoate, 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 Aniline derivatives such as benzophenone, 4-aminobenzonitrile, 3-aminobenzonitrile, p-phenylenediamine, m-phenylenediamine, 4-phenoxyaniline and 3-phenoxyaniline, and further acetoguanamine and 2,4-diamino-6. -[2 '
-Methylimidazolyl- (1)] ethyl-S-triazine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2,3-diaminopyridine, 2,5-diaminopyridine, 2,3,5-tri Heterocyclic compounds such as aminopidine are mentioned.

Of these, those having a melting point of 110 ° C. or higher are particularly preferable. The amine compound may be used alone or as a mixture, and is 1 to 500% by weight based on the aromatic isocyanate compound in order to improve the heat resistance of the background and the wrapping resistance in a well-balanced manner. It is preferable. If the content of the amine compound is less than 1% by weight with respect to the aromatic isocyanate compound, sufficient lap fog resistance cannot be obtained. Further, even if it is used in an amount exceeding 500% by weight, the performance is not improved, and the cost is disadvantageous.

The heat-sensitive recording material using the heat-sensitive coating liquid of 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-naphthylbenzyl 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, metaterphenyl, dibenzyl p-methyl oxalate, oxalic acid (p-chlorobenzyl)
Esters and the like can be mentioned.

The above-mentioned heat-fusible substances may be used alone or as a mixture, and in order to obtain a sufficient heat response, 10 to 10 relative to the aromatic isocyanate compound is used.
It is preferable to use 100% by weight, and further 100 to 6
It is more preferable to use 100% by weight. In order to use these leuco dyes, acidic substances, imino compounds, heat-fusible substances, and amine compounds as heat-sensitive recording materials, it is necessary to form them in the form of dispersion liquids like the aromatic isocyanate compounds. The dispersion is prepared in the same manner as the well-known dispersion method for heat-sensitive materials.

A dispersion liquid of the aromatic isocyanate compound, a dispersion liquid of the imino compound and a dispersion liquid of other additives thus obtained are mixed with a binder or the like to prepare a heat-sensitive coating liquid. A heat-sensitive recording material using the heat-sensitive coating liquid of the present invention can be obtained by forming a heat-sensitive recording layer by applying the heat-sensitive coating liquid on a support by a coating method such as an air knife, a blade or curtain coating.

The heat-sensitive recording material comprises a support and a heat-sensitive recording layer for coloring by heating. 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 each dispersion obtained by finely pulverizing each color-forming component with a binder and coating and drying it on a support. In this case, for example, each color-forming component may be contained in one layer to form a multilayer structure.

As the binder, water-soluble materials such as starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, etc. Examples thereof include latex-based water-insoluble binders such as binders, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers and methyl acrylate-butadiene copolymers.

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, etc. , 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.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples without departing from the gist thereof.

[0031]

Example 1 4,4 ', 4 "-triisocyanate-
2.5 wt% of 2,5-dimethoxyphenylamine 2 g
It was added to 8 g of an aqueous solution of polyvinyl alcohol and pulverized with a paint shaker for 4 hours. The particle size of the dispersion is 1.3μ
m. This dispersion was further heat-treated at 25 ° C. for 1 week.

Separately from this dispersion, 2 g of an imino compound, 1,3-diimino-4,5,6,7-tetrachloroisoindoline, was pulverized with a paint shaker for 4 hours together with 8 g of a 2.5 wt% polyvinyl alcohol aqueous solution. After dispersion, 2.5 g of 15 wt% polyvinyl alcohol was further added as a binder and dispersed for 15 minutes with a paint shaker to obtain a dispersion liquid.

Further, 3-dibutylamino-6-methyl-
2 g of 7-anilinofluoran was pulverized with a paint shaker for 4 hours together with 8 g of a 2.5 wt% aqueous solution of polyvinyl alcohol and dispersed, and then 2.5 g of 15 wt% polyvinyl alcohol was added as a binder and dispersed for 15 minutes with a paint shaker. A dispersion was obtained. Also, 2-
2 g of bis (4-hydroxyphenyl) propane was added to 2.
After pulverizing and dispersing with a paint shaker for 4 hours together with 8 g of a 5 wt% polyvinyl alcohol aqueous solution, further, as a binder, 2.5 g of 15 wt% polyvinyl alcohol.
Was added and dispersed for 15 minutes with a paint shaker to obtain a dispersion liquid.

Further, 2 g of metaterphenyl was pulverized and dispersed with 8 g of a 2.5 wt% aqueous solution of polyvinyl alcohol in a paint shaker for 4 hours, and then 2.5 g of 15 wt% polyvinyl alcohol was further added as a binder and dispersed for 15 minutes in a paint shaker. Then, a dispersion liquid was obtained. Also, 2 g of 3,3′-diaminodiphenyl sulfone was added to 2.
After pulverizing and dispersing with a paint shaker for 4 hours together with 8 g of a 5 wt% polyvinyl alcohol aqueous solution, 2.5 g of 15 wt% polyvinyl alcohol was further added as a binder and dispersed for 15 minutes with a paint shaker to obtain a dispersion liquid.

2.5 g by weight of 2 g of calcium carbonate
After pulverizing and dispersing with 8 g of polyvinyl alcohol aqueous solution in a paint shaker for 4 hours, 2.5 g of 15 wt% polyvinyl alcohol was further added as a binder and dispersed for 15 minutes with a paint shaker to obtain a dispersion liquid. These dispersions were mixed with 4,4 ', 4 "-triisocyanate-
5 parts by weight of 2,5-dimethoxytriphenylamine dispersion liquid, 7.5 parts by weight of 1,3-diimino-4,5,6,7-tetrachloroisoindoline dispersion liquid, 3-dibutylamino-6-methyl-7 5 parts by weight of anilinofluorane dispersion, 10 parts by weight of 2,2-bis (4-hydroxyphenyl) propane dispersion, 20 parts by weight of metaterphenyl dispersion, 5 parts by weight of 3,3'-diaminodiphenylsulfone dispersion. Parts, 50 parts by weight of the calcium carbonate dispersion, and 15 parts by weight of the zinc stearate dispersion having a solid content concentration of 16% by weight with stirring to obtain a heat-sensitive coating liquid.

This heat-sensitive coating liquid was applied onto a base paper having a weight of 50 g / m ² by means of a Bacoater rod number 16, and after drying, it was treated with a super calendar to obtain a heat-sensitive recording material.
The sensitivity was evaluated using a printing tester manufactured by Okura Electric Co., Ltd., and the thermal head was printed using KJT-256-8MGF1 manufactured by Kyocera with an applied voltage of 24 V and a pulse width of 1.0 msec, and then the optical density of the printed sample was measured. The result is an optical density of 1.2
And was good.

To evaluate the resistance of the background to wrapping, the thermosensitive recording material was sandwiched between vinyl chloride wraps, a load of 300 g / cm ² was applied, and the material was left at 40 ° C. for 24 hours to measure the discoloration density of the background. The result was a good optical density of 0.10.
The image storability was evaluated by immersing a sample in which a thermal recording material was printed at a load pressure of 24 V and a pulse width of 1.5 Wsec in a 100% ethanol solution for 15 minutes, and then measuring the concentration of the dried sample. The result was a good optical density of 0.7. The results are shown in Table 1.

[0038]

Example 2 4,4 ', 4 "-triisocyanate-
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the heat treatment condition of the 2,5-dimethoxytriphenylamine dispersion was changed to 5 ° C. for 14 days, and evaluated.

[0039]

Example 3 4,4 ', 4 "-triisocyanate-
When 2,5-dimethoxytriphenylamine was ground with a paint shaker, 0.6 g of ethanol was added and ground, and then the dispersion was heat treated at 25 ° C. for 2 days, and the same treatment as in Example 1 was performed. Create a thermal recording material,
An evaluation was made.

[0040]

Example 4 4,4 ', 4 "-triisocyanate-
2,5-Dimethoxytriphenylamine was dispersed by adding 0.6 g of ethanol with a homodisper to obtain a particle size of 1.9.
After adjusting the thickness to .mu.m, a thermal recording material was prepared and evaluated by the same treatment as in Example 1 except that the dispersion was heat treated at 40.degree. C. for 7 days.

[0041]

Example 5 4,4 ', 4 "-triisocyanate-
2,5-Dimethoxytriphenylamine was dispersed by adding 0.6 g of ethanol with a homodisper to obtain a particle size of 1.9.
After adjusting the thickness to .mu.m, a heat-sensitive recording material was prepared and evaluated by the same treatment as in Example 1 except that the dispersion was heat-treated at 25.degree. C. for 14 days.

[0042]

Comparative Example 1 The same treatment as in Example 1 was carried out except that the 4,4 ′, 4 ″ -triisocyanato-2,5-dimethoxytriphenylamine dispersion liquid of Example 1 was used without heat treatment. A heat-sensitive recording material was prepared and evaluated, and the results are summarized in Table 1.

[0043]

Comparative Example 2 4,4 ', 4 "-triisocyanate-
A heat-sensitive recording material was prepared and evaluated by the same treatment as in Example 1 except that the heat treatment condition of the 2,5-dimethoxytriphenylamine dispersion was 80 ° C. for 5 hours. The results are summarized in Table 1.

[0044]

[Table 1]

[0045]

By using the heat-sensitive coating liquid produced by the present invention, a heat-sensitive recording material having excellent image storability, sensitivity and resistance to wrapping on the background can be obtained.

Claims (1)

[Claims] 1. A process for producing a heat-sensitive coating liquid containing an aromatic isocyanate compound and an imino compound capable of forming a color by reacting with the aromatic isocyanate compound, the dispersion of the isocyanate compound being a dispersion of the imino compound. A method for producing a heat-sensitive coating liquid, which comprises heat-treating under conditions satisfying the following formula before being mixed with. Temperature (Y ° C) and time (X
80-3X>Y> 25 / X (15 ≧ X> 0) 35.75-X / 20>Y> 25 / X (120 ≧ X ≧ 1)
5)