JPS6078783A - Preparation of thermal recording material - Google Patents

Abstract

PURPOSE:To efficiently prepare a thermal recording paper for imparting a recording material high in color forming density and good in storage stability, by coating a support with a composition prepared by dispersing an electron receptive compound having a specific group as a coupler in an org. solvent. CONSTITUTION:In a method for preparing a thermal recording material having an electron doonating colorless dye and an electron receptive compound having a phenolic hydroxyl group [e.g., 2,2'-bis(4-hydroxyphenyl)propane, benzyl 4-hydroxybenzoate or 4-hydroxy-4-chlorodiphenylsulfone] on the same support thereof, the electron receptive compound is dispersed in 0.1-20pts. to 100pts. of this compound of an org. solvent (e.g., benzene or methanol) and the resulting dispersion is applied to the support. By this method, the thickening of the coating solution is reduced and a coupler is efficiently dispersed and a thermal recording material imparting a recording material high in color forming density and good in storage stability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a heat-sensitive recording material,
In particular, the present invention relates to 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.

(Prior art) ゛1■ Child-donating colorless dye (hereinafter referred to as "coloring agent"), I
- Heat-sensitive recording materials that utilize the coloring reaction of electron-accepting compounds (hereinafter referred to as "color developers") are, for example, published by Tokko Akihiro 3-Hiroshi/1
, No. 0, US Pat. No. 23, No. 002, etc. It is well known that when an electron-accepting compound having a phenolic hydroxyl group is used as a color developer in these heat-sensitive recording materials, 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) The object of the present invention is to provide a method for producing a heat-sensitive recording material that eliminates these drawbacks and provides a recording material with high color density and good storage stability by efficiently (dispersing) a color developer. That's true.

(Structure of the Invention→ The 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.

This was achieved by a method for producing a heat-sensitive recording material, which comprises dispersing an electron-accepting compound in an organic solvent in an amount of Ool to 20 parts per ioo part of the electron-accepting compound, and then coating it on a support.

The electron-accepting compound having a phenolic hydroxyl group according to the present invention is a compound having seven or more phenolic hydroxyl groups and having a carbon atom number a-it, and among these, preferable examples are the following general formulas (I) to ( 1).

lt.

In the above general formulas (I) to (III), X is an alkylene residue, an aralkylene residue, a cycloalkylene residue, or S
O2, R is an aryl group, an alkyl group, a cycloalkyl group, an aralkyl group, an alkoxy group, an aryloxy group,
The primary amino group and the secondary amino group are R1 and R
1' may be the same or different and represents a hydrogen atom, an alkyl group, an aryl group, a halogen atom or an electron-withdrawing group.

COR///, -CO2R/I/, -3Q2]%
/// , -3Q 3R/II, -CN(R', R"
%R"' represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group).

In the above general formula (I), among the groups represented by X,
Alkylene residue with carbon atoms /~/2, carbon atoms 7~
12 aralkylene residues, 7-chloroalkylene residues with carbon atoms <<-io, and SO2 are particularly preferred, alkylene residues with carbon atoms/♂, cycloalkylene residues with carbon atoms j to 7, and S02. preferable.

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 (n) and (III), an aryl group having 6 to /r carbon atoms, an alkyl group having /-/J carbon atoms, and a cycloalkyl group having v to IO carbon atoms. group, aralkyl group having 7 to /I carbon atoms, alkyl group having 2 carbon atoms, -koxy group, aryloxy group having A-/♂ carbon atoms, 7th-class amino group having 7 to 2 carbon atoms, /-/r carbon atoms and secondary amino groups are preferred, especially aryl groups having 6 to 1 carbon atoms, alkyl groups having 1 carbon atoms, cycloalkyl groups having 7 to 7 carbon atoms, and secondary amino groups having 7 to 1 carbon atoms. Aralkyl group, number of carbon atoms/~t alkoxy7')Ii, number of carbon atoms t~
An aryloxy group having /2 carbon atoms, a primary amino group and a secondary amine group having /2 carbon atoms are preferred.

In the above general formulas (I) to (Ul), R1 and R1'
Among the substituents represented by hydrogen atom, number of carbon atoms l-♂
Preferred are alkyl groups having 7 to 2 carbon atoms, aryl groups having t to 2 carbon atoms, chlorine atoms, bromine atoms, and electron-withdrawing groups having 1 or less carbon atoms.
Particularly hydrogen atoms, alkyl groups having 1-1 carbon atoms, aralkyl groups having 7 to 2 carbon atoms, aryl groups having 6 to 1 carbon atoms, chlorine atoms, acyl groups having 1 carbon atom/-1, and carbon atoms Preferred are a substituted carbamoyl group having 2 to 4 carbon atoms, a sulfonyl group having 1 to 3 carbon atoms, an aryl-disulfonyl group having 6 to 1 carbon atoms, and a substituted sulfamoyl group having 1 to 4 carbon atoms.

The organic solvent according to the present invention is liquid at room temperature or has a melting point of 0.
'C or less, the solubility in water is 0. / or more, aromatic compound having 6 to 20 carbon atoms, number of carbon atoms /
-10 chlorinated hydrocarbon compounds, number of carbon atoms/-
, 20, ketone compounds having 3 to 20 carbon atoms, carboxylic acid ester compounds having 3 to 20 carbon atoms, ether compounds having gluco θ having carbon atoms, and amide compounds having 3 to 20 carbon atoms. In particular, aromatic compounds having A-10 carbon atoms, halogenated hydrocarbon compounds having 1-≠ carbon atoms, alcohol compounds having 1-10 carbon atoms, ketone compounds having 3 to 10 carbon atoms, and 3 to 10 carbon atoms. Preferred are carboxylic acid ester compounds having 10 carbon atoms, ether compounds having hi to io carbon atoms, and amide compounds having 3 to lθ carbon atoms. Among these, water-soluble ones are particularly suitable for handling.

The amount of organic solvent used is preferably 0.1 to U 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 100C or less and a solubility in water of 50% or more. ˜/θ portion is preferable. Further, the amount of organic solvent other than this is preferably 0.1 to 70 parts, particularly 0.1 to 70 parts. / to 5 parts is preferred.

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 a halogen atom, an alcoholic hydroxyl group, a carbonyl group, an oxycarbonyl group, an etheric 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 (I) λ1. 2'-bis(Kucht'roxyphenylonpropane, co, λ'-bis(Hiro-hydroxyphenyl)butane, λ, 2'-bis(Hiro-hydroxyphenyl)pentane, λ , 2'-bis(terhydroxyphenyl)-3-methylpropane, 2.+2'-bis(terhydroxyphenyl)hexane, co.

λ'-bis(Hiro-hydroxyphenyl)-3-methylbutane, λ1.2'-Bis(Hiro-hydroxyphenyl) to buta/, 2v 2'-bis(terhydroxyphenyl)-3-ethyl to methane, λ, -2'-bis(Hiro1 hydroxyphenyl), -3-methyl with methane, /, l'-
Bis(terhydroxyphenyl)butane, ll//-bis(4A-hydroxyphenyl)butane, /,/'-
Bis(Hiro-hydroxyphenyl)-2-ethyl, λ, 2'-His(J-chloro-terhydroxyphenyl)pro/ξ, 2,2/-Bis(3-chloro-Hiro-hydroxyphenyl) )-3-Ethylhebutane, l.

l-bis(Hiro-hydroxyphenyl)cyclohexane,
Bis-(3-ethyl-hiro-hydroxyphenyl) sulfone, bis-(3-bu≠-hydroxyphenyl) sulfone, his-(3-n-propyl-μm hydroxyphenyl) sulfone, his-(3-ethyl -μm hydroxyphenyl) sulfone, bis-(3-chloroda-hydroxyphenyl) sulfone, bis-(2,!-dimethyl-hydroxyphenyl) sulfone, bis-(2-methyl-guhydroxy-, t--j' ropylphenyl) sulfone, bis=(,2,J-dimethyl-R≠-hydroxyphenyl)sulfone, bis-(,2,j-cyclo-hydroxyphenyl)sulfone, bis-(λ-
methyl-hydroxyphenyl) sulfone, bis-(
2-ethyl-terhydroxyphenyl) sulfone, bis-(2-isopropyl-terhydroxyphenyl) sulfone 2 , 21-bis(p-cresol) sulfo/,
2.2'-bis(p-isopropylphenol)sulfone, 21λ'-bis(p-1-butylphenol)sulfone, λ,2'-bis(p-sec-butylphenol)sulfone, 2.2'-bis(p-sec-butylphenol)sulfone, -amylphenol)sulfone1. z'-'-bis(p-t-octylphenol) sulfone, 2゜λ'-his(p-cumylphenol) sulfone, λ, 2'-bis(p-cyclohexylphenol) sulfone% 21''-bis (p
-phenylphenol) sulfone, +2,2'-bis(
p-Chlorophenol'sulfone, Examples of general formula (II) hydroxybenzoic acid benzyl ester, g-hydroxybenzoic acid p-chlorobenzyl ester, ≠-hydroΦdibenzopheno7, <z-hydroxyphenylhexyl ketone, hydroxyphenylbenzyl ketone,
3-Chloro-Hiro-hydroxybenzo'4 acid-p-chloropencyl ester, 1N-be/Giro-Hiro-hydroxypenzamide, example of general formula (In) Hiro-hydroxy-≠'-chlorodiphenylsulfone, ≠
-Hydroxy Hiro'-Methyldiphenylsulfone, Hiro-
Hydroxy-Hiroshi'-methoxydiphenylsulfone, Guhydroky-3', 41-dimethyldiphenylsulfone, ≠-hydroxydiphenylsulfone, j-chloro-l-hydroxy-≠'-methyldiphenylsulfone, ≠-hydroxyphenyl, cyclohexylsulfone Hiro -Hydroxy-Hiro'-β-7enethyloxydiphenylsulfone, ≠-hydroxy-/-butylsulfonylbenzene, hydroxy-/-cyclohexylsulfonylbenzene, Hiro-hydroxy-/-benzylsulfonylbenzene, p-N-7' Chilsulfamoylphenol,
p-N-hexylsulfamoylphenol, p-N-
Benzylsulfamoylphenol, p-N-α-methylbenzylsulfamoylphenol, 2-chloro-
F-N-benzylsulfamoylphenol, p-N-
Phenylsulfamoylphenol, p-N-3-tolylsulfamoylphenol, p-N-2-) Lylsulfamoylphenol, J-chloro-μ-N-phenylsulfamoylphenol, p-N- Methyl-N-phenylsulfamoylphenol, p N-methyl-N
-Benzylsulfamoylphenol, Hiro-hemethyl-N-phenylsulfamoyl-/-naphthol, ≠-
Hebutylsulfamoyl l-naphthol, F-N-
Benzylsulfamoyl-/-naphthol,! -N-benzylsulfamoyl-7-naphthol, t-~-benzylsulfamoyl-2-naphthol, l-N-benzylsulfamoyl-2-naphthol, A, f-bis-(N-benzyl sulfamoyl)-conaphthol,
t,♂-bis(N-butylsulfamoyl)-2-naphthol, g-β-naphthyloxysulfonylphenol, Hiro-p-t-7f rufenoxysulfonylphenol, Hiro-phenoyacissulfonyl-l-naphthol,
Goo p-isopropylphenoxysulfonyl-7-naphthol, ≠-p-tolyloxysulfonyl=l-naphthol, etc.

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 the organic solvent according to the present invention will be shown, but the present invention is not limited thereto.

Benzene, toluene, xylene, chloroform, dichloromethylene, methyl chloroform, methanol, ethanol, isopropanol, butanol, hensyl alcohol, acetone, methyl ethyl chloride, ethyl acetate, butyl acetate, tetra-r dorofuran, dimethyl formamide , dimethylacetamide, methyl cellosolve, ethyl cellosolve, ethylene glycol, propylene glycol, diethylene glycol, etc. 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, xanthine compounds, thiazine compounds, spiropyran compounds, etc. are used.

To illustrate some of these, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-t-dimethylaminophthalide (i.e., crystal violet lactone), 3゜3-bis(p- dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(/,j-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-
3-(2-methylindol-3-yl)phthalide, etc., and diphenylmethane compounds include φ, ri'-
Bis-dimethylaminobenzhydro/benzyl ether, N-halophenyl-leukoolamine, H-2,≠,
! -Trichlorophenylleucoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, λ-
Rebenzylamino-6-diethylaminofluorane λ
-anilino-t-diethylaminofluorane, no-anilino-3-methyl-6-ethylaminofluorane, co-anilino-3-methyl-6-cyclohexylmethylaminofluorane/, λ-0-rio oanilino-t- Diethylaminofluorane, λ-m-chloroanilino-6-
Ethylaminofluorane, λ-(3,a-dichloroanilino)-t-diethylaminofluorane, 2-octylamino-6--diethylaminofluorane, colahexylamino-t-diethylaminofluorane 1.2-
m-) dichloromethylanilino to 1-diethylaminofluorane, λ-butylamino-J-chloro&-diethylaminofluoran, Koet beef diethylamino-3-
Chloro-4-diethylaminofluorane, λ-anilino-3-chloro-t-diethylaminofluorane, -1-diphenylamino-6-ethylaminofluorane, -1-anilino-3-methyl-t-diphenylaminofluorane, no-anilino-3- Methyl! -Chloro-t-diethylaminofluorane, 2-anilino-3-methyl-t
-diethylamino-7-methylfluorane, λ-anilino-3-methoxy-6-cyptylaminofluorane, λ
-〇-Chloroanilino t-dibutylaminofluora/
, coal-chloroanilino-3-ethoxy-6-diethylaminofluorane, cophenylated-t-diethylaminofluorane, etc. Thiazine-based compounds include benzoylleucomethyleffluoran, p-nitrobenzylleucomethylene blue, etc. Examples of spiro-based compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spirozonaphthopyran 1 31 J'-cyclolosevirodinaphthopyran, 3-benzylspiro-sinaphthopyran, 3-methylnaf)-(J -methoxy-benzo)-spiropyran, 3-propyl-spiro-dibenzopyran, and the like. 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 media such as a sand mill or an attriter may be used.

・0 as a media. Hard solid particles such as lr-/1 mm glass beads, iron balls, ceramics, and Otsutawa sand are used. In addition, a dispersing machine that does not use media may be used, and specific examples thereof include those using blades, such as propeller mixer, homo mixer, kedimir, agitator, jet mixer, pipeline agitator, homogenizer, and tank. Various models such as sing agitators have been commercialized.

When applying the method of the present invention, in advance, in water to be dispersed, electron-accepting compounds, electron-donating colorless dyes, surfactants, dispersants, water-soluble polymers, latex, metal salts, metal oxides, etc. , 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 the 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, and hydroxyethyl cellulose. etc. can be mentioned.

In particular, water-soluble binders such as gum arabic, polyvinyl alcohol, hydroxymethyl cellulose, and carboxymethyl cellulose are desirable in relation to the dispersion medium (solvent).

As a specific manufacturing method, the electron-accepting compound according to the present invention and an organic bath agent are added to 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 producing the heat-sensitive recording material according to the present invention will be described.

The most common method for producing heat-sensitive recording materials is to disperse the above-mentioned colorless electron-donating dye in a water-soluble polymer solution having a weight of 1 to 10% by means of a ball mill, sand mill, or the like. On the other hand, the electron-accepting compound according to the present invention and the organic solvent are dispersed in a water-soluble polymer solution of /-10 weight tm using a disperser. After mixing both, kaolin, Merck, calcium carbonate (preferably light calcium carbonate)
A coating liquid is created by adding inorganic pigments such as. 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.

Coating fluids are most commonly applied onto base paper.

Generally, the coating amount is 2 to 109/m as solid content,
The lower limit is determined by the density during heat color development, and the upper limit is determined mainly by economic constraints.

Thermofusible substances include erucic acid, stearic acid, behenic acid, palmitic acid, stearamide,
Behenic acid amide, stearic acid anilide, stearic acid toluiside, N-myristoyl-p-anisidine, N-
Myristoyl-p-phenetidine, l-methoxycarbonyl-≠-N-stearylcarbamoylbenzene, to-
Octadecyl urea, N-hexadecyl urea, N, N
'-Didodecyl urea, phenylcarbamoyl oxy7dodeca7,p,-t-butylphenolphenoxyacetate, p-phenylphenol-p-chlorophenoxyacetate, u,l-isoprohyritenebismeth I? 7
Benzene, β-phenylethyl-p-phenylphenyl ether, λ-p-chlorobenzyloxynaphthalene,
2-benzyloxynaphthalene/, l-benzyloxynaphthalene, λ-phenoxyacetyloxynaphthalene,
Phthalic acid diphenyl ester, /-hydroxyconaphthoic 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) Sample/Preparation of ~B 2-anilino-3-chloro- which is an electron-donating colorless dye
Aqueous solution of t-diethylaminofluorane jgfj polyvinyl alcohol (touch chlorine value, degree of polymerization 1000)!
The mixture was dispersed with Og in a boiler for a day and a night. On the other hand, the electron-accepting compound /, /-bis (≠-hydroxyphenyl) cyclo to beef san log, water! After predispersing Oml with the organic solvent shown in Table 1 for 2 hours in a ball mill, a 10% polyvinyl alcohol aqueous solution zog' (i
-In addition, they were dispersed all day and night. Further, the Jffl dispersion was mixed with λ-benzyloxynaphthalene 71011f, a heat-fusifying agent, and a fb polyvinyl alcohol aqueous solution 1009 for one day in a ball mill.
Joshia kaolin) and zog were added (dispersed), and 50 qb dispersion of paraffin wax emulsion (Chukyo Yushi Cellosol #≠2i) rg was added to prepare a coating liquid.

The coating liquid has a solid content coating amount of A! Apply to 17m2 and heat at 600C.
After drying for 1 minute at a linear pressure of 1.0 KPW/crn, the coated paper was obtained using a swivel-saw calender.

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) Creation of comparison sample The same recipe as that used to create sample/-4 (same recipe,
A similar test was conducted except that only the organic solvent was used.

The coated paper had almost no fog (but when it was heated and colored with a heating stamp, it developed a high degree of color. The coating viscosity is also shown in Table 1.

Table 1 (Effects of the Invention) Table 7 clearly shows that the dispersion method of the present invention causes less thickening of the coating liquid. Applying a coating with a high coating viscosity tends to cause uneven coating (Also, coatings whose viscosity is lowered by adding a dispersion medium are industrially disadvantageous due to a decrease in the coating amount and an increase in drying load. In this case, the coating liquid viscosity is 10
A dispersion method of 0 cp or less is preferable, and the dispersion method of the present invention is an extremely excellent method.

That is, according to the present invention, a fine dispersion can be prepared with high efficiency and (b) extremely good reproducibility with respect to 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] 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 amount of the electron-accepting compound is 0. 1. A method for producing a heat-sensitive recording material, which comprises dispersing the material using 20 parts of an organic solvent and then coating the material on a support.