JPH0445352B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a heat-sensitive recording material, and in particular, the present invention relates to a method for producing a heat-sensitive recording material, in particular a method for producing a heat-sensitive recording material having an electron-donating colorless dye and an electron-accepting compound having a phenolic hydroxyl group on the same support. It is about the method. (Prior art) Electron-donating colorless dye (hereinafter referred to as "color former")
For example, heat-sensitive recording materials that utilize the color-forming reaction of electron-accepting compounds and electron-accepting compounds (hereinafter referred to as "color developers") were developed by
No. 43-4160, US Pat. No. 2,939,009, etc. In these heat-sensitive recording materials, when an electron-accepting compound having a phenolic hydroxyl group is used as a color developer, it is well known that the particle size affects the performance of the heat-sensitive recording material. Various dispersion methods have been devised. However, when dispersing an electron-accepting compound having a phenolic hydroxyl group, there are drawbacks such as the finer the particle size, the higher the viscosity of the dispersion, making it difficult to disperse and coat. (Object of the Invention) An object of the present invention is to provide a method for producing a heat-sensitive recording material that eliminates these drawbacks, efficiently disperses a color developer, and provides a recording material with high color density and good storage stability. It is. (Structure of the Invention) An object of the present invention is to provide a method for producing a heat-sensitive recording material having an electron-donating colorless dye and an electron-accepting compound having a phenolic hydroxyl group on the same support. compound 100
According to a method for producing a heat-sensitive recording material, which comprises dispersing the material in water using an organic solvent that is liquid at room temperature and has a solubility in water of 5% or more in an amount of 0.1 to 20 parts per part of the heat-sensitive recording material. achieved. The electron-accepting compound having a phenolic hydroxyl group according to the present invention has one or more phenolic hydroxyl groups. It is a compound having 6 to 28 carbon atoms, and among these, preferable examples are the following general formulas () to ().
It is expressed as

[Formula] In the above general formulas () to (), X is an alkylene residue, an aralkylene residue, a cycloalkylene residue, or _SO2 , and R is an aryl group, an alkyl group, a cycloalkyne group, an aralkyl group, an alkoxy group,
In the aryloxy group, primary amino group, and secondary amino group, R ₁ and R ₁ ' may be the same or different and represent a hydrogen atom, an alkyl group, an aryl group, a halogen atom, or an electron-withdrawing ability. As an electron-withdrawing group,

【formula】

[Formula] -COR, -CO ₂ R, -SO ₂ R, -SO ₃ R, -CN (R', R'', R is a hydrogen atom,
Represents an alkyl group, an aralkyl group or an aryl group. ) etc. In the above general formula (), among the groups represented by ₂ is particularly preferred, particularly an alkylene residue having 1 to 8 carbon atoms,
Cycloalkylene residue having 5 to 7 carbon atoms and
_SO2 is preferred. The substitution position of X is preferably ortho or para to the phenolic hydroxyl group. Among the substituents represented by R in the above general formulas () and (), an aryl group having 6 to 18 carbon atoms,
Alkyl group having 1 to 12 carbon atoms, 4 to 4 carbon atoms
10 cycloalkyl groups, aralkyl groups having 7 to 18 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, aryloxy groups having 6 to 18 carbon atoms, primary amino groups having 1 to 18 carbon atoms, and 2 Preferred are amino groups, particularly aryl groups having 6 to 12 carbon atoms, alkyl groups having 1 to 8 carbon atoms, and 5 to 7 carbon atoms.
Cycloalkyl group having 7 to 12 carbon atoms, aralkyl group having 7 to 12 carbon atoms, alkoxy group having 1 to 8 carbon atoms, aryloxy group having 6 to 12 carbon atoms, 1 carbon atom
~12 primary amino groups and secondary amino groups are preferred. In the above general formulas () to (), R ₁ and
Among the substituents represented by R ₁ ', hydrogen atoms, alkyl groups having 1 to 8 carbon atoms, aralkyl groups having 7 to 12 carbon atoms, aryl groups having 6 to 12 carbon atoms, chlorine atoms, bromine atoms, and carbon Electron-withdrawing groups having 18 or less atoms are preferred, particularly hydrogen atoms, alkyl groups having 1 to 4 carbon atoms, aralkyl groups having 7 to 9 carbon atoms, aryl groups having 6 to 9 carbon atoms, chlorine atoms, and carbon atoms. Acyl group having 1 to 8 atoms, 2 carbon atoms
-9 substituted carbamoyl groups, sulfonyl groups having 1 to 8 carbon atoms, aryloxysulfonyl groups having 6 to 9 carbon atoms, and substituted sulfamoyl groups having 1 to 8 carbon atoms are preferred. An alcohol compound having 1 to 6 carbon atoms, a ketone compound having 3 to 6 carbon atoms, a carboxylic acid ester compound having 3 to 5 carbon atoms, an ether compound having 4 to 6 carbon atoms in an organic solvent according to the present invention, Amide compounds having 3 to 10 carbon atoms are preferred. In particular, alcohol compounds having 1 to 3 carbon atoms, ketone compounds having 3 to 4 carbon atoms, and 3 to 4 carbon atoms.
carboxylic acid ester compound having 4 to 6 carbon atoms
Ether compounds and amide compounds having 3 to 6 carbon atoms are preferred. Among these, those with high water solubility are particularly suitable for handling. The amount of the organic solvent used is preferably 0.1 to 20 parts, particularly 0.5 to 10 parts, per 100 parts of the electron-accepting compound having a phenolic hydroxyl group, in the case of a solvent with a boiling point of 100° C. or less and a solubility in water of 50% or more.
part is preferred. In the case of organic solvents other than these, the amount is preferably 0.1 to 10 parts, and particularly preferably 0.1 to 5 parts. Among the organic solvents according to the present invention, those having a group that forms a hydrogen bond with the phenolic hydroxyl group of the electron-accepting compound are particularly preferred. Specifically, those having an alcoholic hydroxyl group, a carbonyl group, an oxycarbonyl group, an ether oxygen atom, and an amide group are preferable. Next, specific examples of the electron-accepting compound having a phenolic hydroxyl group according to the present invention will be shown, but the present invention is not limited thereto. Examples of general formula () 2,2'-bis(4-hydroxyphenyl)propane, 2,2'-bis(4-hydroxyphenyl)
Butane, 2,2'-bis(4-hydroxyphenyl)pentane, 2,2'-bis(hydroxyphenyl)-3-methylpropane, 2,2'-bis(4-
hydroxyphenyl)hexane, 2,2'bis(4
-hydroxyphenyl)-3-methylbutane, 2,
2'-bis(4-hydroxyphenyl)heptane,
2,2'-bis(4-hydroxyphenyl)-3-
Ethylpentane, 2,2'-bis(4-hydroxyphenyl)-3-methylpentane, 1,1'-bis(4-hydroxyphenyl)butane, 1,1'-bis(4-hydroxyphenyl) ) heptane, 1,
1'-bis(4-hydroxyphenyl)-2-ethylhexane, 2,2'-bis(3-chloro-4-hydroxyphenyl)propane, 2,2'-bis(3
-chloro-4-hydroxyphenyl)-3-ethylheptane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis-(3-ethyl-4
-hydroxyphenyl)sulfone, bis-(3-
Butyl-4-hydroxyphenyl) sulfone, bis-(3-n-propyl-4-hydroxyphenyl) sulfone, bis-(3-ethyl-4-hydroxyphenyl) sulfone, bis-(3-chloro-
4-hydroxyphenyl)sulfone, bis-(2,
5-dimethyl-4-hydroxyphenyl)sulfone, bis-(2-methyl-4-hydroxy-5-
propylphenyl) sulfone, bis-(2,3-
dimethyl-4-hydroxyphenyl) sulfone,
Bis-(2,5-dichloro,4-hydroxyphenyl)sulfone, bis-(2-methyl-4-hydroxyphenyl)sulfone, bis-(2-ethyl-4-hydroxyphenyl)sulfone, bis-
(2-isopropyl-4-hydroxyphenyl)
Sulfone, 2,2'-bis(p-cresol)sulfone, 2,2'-bis(p-isopropylphenol)sulfone, 2,2'-bis(p-t-butylphenol)sulfone, 2,2'- Bis(p-sec-
butylphenol) sulfone, 2,2'-bis(p
-t-amylphenol) sulfone, 2,2'-bis(pt-octylphenol) sulfone,
2,2'-bis(p-cumylphenol) sulfone, 2,2'-bis(p-cyclohexyphenol) sulfone, 2,2'-bis(p-phenylphenol) sulfone, 2,2'- Bis(p-chlorophenol)sulfone, example of general formula () 4-hydroxybenzoic acid benzyl ester, 4
-Hydroxybenzoic acid p-chlorobenzyl ester, 4-hydroxybenzophenone, 4-hydroxyphenylhexyl ketone, 4-hydroxyphenylbenzyl ketone, 3-chloro-4-hydroxybenzoic acid p-chlorobenzyl ester,
N-Benzyl-4-hydroxybenzamide, Examples of general formula () 4-hydroxy-4'-chlorodiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxydiphenyl Sulfone, 4-hydroxy-3',4'-dimethyldiphenylsulfone, 4-hydroxydiphenylsulfone, 3-chloro-4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxyphenyl, cyclohexylsulfone 4- Hydroxy-
4′-β-phenethyloxydiphenyl sulfone,
4-hydroxy-1-butylsulfonylbenzene, 4-hydroxy-1-cyclohexylsulfonylbenzene, 4-hydroxy-1-benzylsulfonylbenzene, p-N-butylsulfamoylphenol, p-N-hexylsulfamoylphenol, p-N-benzylsulfamoylphenol, p-N-α-methylbenzylsulfamoylphenol, 2-chloro-4-N-benzylsulfamoylphenol, p-N-phenylsulfamoylphenol, p- N-3-tolylsulfamoylphenol, p-N-2-tolylsulfamoylphenol, 2-chloro-4-N
-Phenylsulfamoylphenol, p-N-
Methyl-N-phenylsulfamoylphenol, p-N-methyl-N-benzylsulfamoylphenol, 4-N-methyl-N-phenylsulfamoyl-1-naphthol, 4-N-butylsulfur Moyl-1-naphthol, 4-N-benzylsulfamoyl-1-naphthol, 5-N-
Benzylsulfamoyl-1-naphthol, 6-
N-benzylsulfamoyl-2-naphthol,
8-N-benzylsulfamoyl-2-naphthol, 6,8-bis-(N-benzylsulfamoyl)-2-naphthol, 6,8-bis-(N-butylsulfamoyl)-2-naphthol , 4-β-
Naphthyloxysulfonylphenol, 4-p-
t-butylphenoxysulfonylphenol, 4
-phenoxysulfonyl-1-naphthol, 4-
p-isopropylphenoxysulfonyl-1-naphthol, 4-p-tolyloxysulfonyl-1
- Naphthol et al. These may be used alone, in combination, or in combination with other electron-accepting compounds (eg, activated clay, kaolin, metal salts of aromatic carboxylic acids, phenol formaldehyde resins, etc.). Next, specific examples of organic solvents according to the present invention will be shown.
The present invention is not limited to these. methanol, ethanol, isopropanol,
Butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, dimethyl formamide, dimethyl acetamide, methyl cellosolve, ethyl cellosolve, ethylene glycol,
Examples include propylene glycol and diethylene glycol. These may be added during dispersion or may be contained in the electron-accepting compound from the beginning. As the electron-donating colorless dye used in the present invention, triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds, etc. are used. To illustrate some of these, triarylmethane compounds include 3-3-bis(p-dimethylaminophenol)-6-dimethylaminophthalide (i.e., crystal violet lactone);
3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenol)-
3-(1,3-dimethylindol-3-yl)
Phthalide, 3-(p-dimethylaminophenol)
-3-(2-methylindol-3-yl)phthalide, etc. Diphenylmethane compounds include 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoauramine, -2,4,5-trichlorophenylleucoolamine, etc., and xanthene compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, 2- Dibenzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2-o-chloroanilino-6-diethylaminofluorane, 2-m-chloroanilino-6-diethylaminofluorane, 2-(3,4-dichloroanilino)-6-diethylaminofluorane,
2-octylamino-6-diethylaminofluorane, 2-dihexylamino-6-diethylaminofluorane, 2-m-trichloromethylanilino-6-diethylaminofluorane, 2-butylamino-3-chloro-6-diethylaminofluorane Oran, 2-ethoxyethylamino-3-chloro-
6-diethylaminofluorane, 2-anilino-
3-chloro-6-diethylaminofluorane, 2
-diphenylamino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diphenylaminofluorane, 2-anilino-3-methyl-5-chloro-6-diethylaminofluorane,
2-anilino-3-methyl-6-diethylamino-7-methylfluorane, 2-anilino-3-methoxy-6-dibutylaminofluorane, 2-o
-chloroanilino-6-dibutylaminofluorane, 2-p-chloroanilino-3-ethoxy-6
-diethylaminofluorane, 2-phenyl-6
-diethylaminofluorane, etc. Thiazine compounds include benzoyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, etc., and spiro compounds include 3-methyl-
Spiro-dinaphthopyran, 3-ethyl-spiro-
Dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, 3-propyl-spiro-
Examples include dibenzopyran. These may be used alone or in combination. Next, the dispersion method according to the present invention will be described. For the dispersion method, for example, a dispersion machine using a media such as a sand mill or an attriter may be used. Glass beads of 0.6 to 15 mm are used as media.
Hard solid particles such as iron balls, ceramics, and Otsutawa sand are used. Further, a dispersing machine that does not use a media may be used, and specific examples thereof include those using blades, such as propeller mixer, homo mixer, kedimir, agitator, jet mixer, pipeline agitator,
Various types of homogenizers, tansing agitators, etc. have been commercialized. When applying the method of the present invention, the electron-accepting compound used in advance in the water to be dispersed,
Electron-donating colorless dyes, surfactants, dispersants, water-soluble polymers, latexes, metal salts, metal oxides, hydroxides, carbonates, or inorganic pigments may be added. Further, the electron-donating colorless dye and the electron-accepting compound used together if necessary may be separately dispersed and then mixed. Water is most desirable as a dispersion medium. Examples of binders used in the present invention include styrene-butadiene copolymers, alkyd resins, acrylamide copolymers, vinyl chloride-vinyl acetate copolymers, styrene-maleic anhydride copolymers, synthetic rubbers, gum arabic, polyvinyl alcohol, hydroxyethyl Examples include cellulose. Especially in relation to the dispersion medium (solvent), gum arabic,
Water-soluble binders such as polyvinyl alcohol, hydroxymethylcellulose, and carboxymethylcellulose are preferred. As a specific manufacturing method, the electron-accepting compound according to the present invention and an organic solvent are placed in water to be dispersed, and pre-dispersed as necessary in a dispersing machine.
Furthermore, a dispersant and, if necessary, additives and binders are added and dispersed. Next, a specific method for manufacturing the heat-sensitive recording material according to the present invention will be described. The most common manufacturing method for heat-sensitive recording materials is
The electron-donating colorless dye mentioned above is dispersed in a 1 to 10% by weight water-soluble polymer solution using a ball mill, a sand mill, or the like. On the other hand, the electron-accepting compound according to the present invention and the organic solvent are contained in an amount of 1 to 10% by weight.
Disperse in a water-soluble polymer solution using a dispersion machine. After mixing the two, an inorganic pigment such as kaolin, talc, calcium carbonate (preferably light calcium carbonate) is added to prepare a coating liquid. A paraffin wax emulsion, a latex binder, a thermofusible substance, a metal soap, an antioxidant, an ultraviolet absorber, etc. can be added to this as necessary. Paints are most commonly applied onto base paper. Generally, the coating amount is 2 to 10 g/m ² in terms of solid content, with the lower limit determined by the density during color development by heating, and the upper limit determined mainly by economic constraints. As the thermofusible substance, erucic acid,
Stearic acid, behenic acid, palmitic acid, stearamide, behenic acid amide, stearanilide, stearic acid toluidide, N-myristoyl-p-anisidine, N-myristoyl-p-
phenetidine, 1-methoxycarbonyl-4-N
-stearylcarbamoylbenzene, N-octadecylurea, N-hexadecylurea, N,
N'-ditodecyl urea, phenylcarbamoyloxide dodecane. p-t-butylphenol phenoxy acetate, p-phenylphenol-p
-chlorophenoxy acetate, 4,4'-isopropylidene bismethoxybenzene, β-phenylethyl-p-phenyl phenyl ether, 2-p
-Chlorobenzyloxynaphthalene, 2-benzyloxynaphthalene, 1-benzyloxynaphthalene, 2-phenoxyacetyloxynaphthalene, phthalic acid diphenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 2-benzoyloxynaphthalene , p-benzyloxybenzoic acid benzyl ester, hydroquinone acetate, etc. are used. (Example) Examples will be shown below, but the present invention is not limited only to these examples. (1) Preparation of samples 1 to 6 2-anilino-3- which is an electron-donating colorless dye
5g of chloro-6-diethylaminofluorane
% polyvinyl alcohol (sapon number 99%, degree of polymerization
1000) Dispersed with 50g of aqueous solution in a ball mill overnight. On the other hand, the electron-accepting compound 1,1-
Bis(4-hydroxyphenyl)cyclohexane
After preliminary dispersion of 10 g and 50 ml of water together with the organic solvent shown in Table 1 in a ball mill for 2 hours, 50 g of a 10% polyvinyl alcohol aqueous solution was added and the mixture was dispersed overnight. Furthermore, 10 g of 2-benzyloxynaphthalene, which is a heat-fusifying agent, was dispersed overnight in a ball mill with 100 g of a 5% polyvinyl alcohol aqueous solution, and after mixing these three dispersions, 20 g of kaolin (diyodiakaolin) was added and dispersed well. Further, 5 g of a 50% dispersion of paraffin wax emulsion (Chukyo Yushi Cellosol #428) was added to prepare a coating liquid. The coating liquid was applied onto base paper with a basis weight of 50 g/m ² at a solid content of 6 g/m ² and heated at 60°C.
After drying for 1 minute, a coated paper was obtained by supercalendering at a linear pressure of 60 KgW/cm. Each of the coated papers had almost no fog, and when heated and colored using a heating stamp, the colors developed with high density. Table 1 shows the coating fluid viscosity. (2) Preparation of Comparative Samples A similar test was conducted using exactly the same formulation as that used to prepare Samples 1 to 6, except that only the organic solvent was used. The coated paper had almost no fog, and when heated and colored using a heating stamp, the color developed with high density. The coating viscosity is also shown in Table 1.

【table】

[Table] (Effects of the Invention) Table 1 shows that the dispersion method of the present invention clearly causes less thickening of the coating liquid. Applying something with a high coating viscosity tends to cause uneven coating, and
Products in which a dispersion medium is added to lower the viscosity are industrially disadvantageous due to a decrease in the amount of coating and an increase in drying load. In the case of this sample, the coating liquid viscosity is preferably 100 cp or less, and the dispersion method of the present invention is an extremely excellent method. That is, according to the present invention, (a) a fine dispersion liquid can be efficiently prepared without increasing the viscosity of the liquid, and (b) extremely good reproducibility of the degree of dispersion can be obtained. (c) Easy to apply to support (d) No fog on coated paper (e) High color density.

Claims (1)

[Claims] 1. In a method for producing a heat-sensitive recording material having an electron-donating colorless dye and an electron-accepting compound having a phenolic hydroxyl group on the same support, the electron-accepting compound is added in an amount of 0.1 to 20 parts per 100 parts of the electron-accepting compound. Liquid at room temperature, solubility in water is 5%
A method for producing a heat-sensitive recording material, which comprises dispersing it in water using the above organic solvent and then coating it on a support.