JPH03128286A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material excellent in oil resistance by using a specific compound as an electron acceptive compound. CONSTITUTION:In a thermal recording material consisting of an electron donating leuco dye and an electron acceptive compound, a compound represented by formula 1 (wherein R is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group or an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group or butoxy group and n is 2 or 3) is used as the electron acceptive compound. As the electron donating leuco dye, a leuco compound such as a triphenylmethane dye, a fluorane dye, a phenothiazine dye, an auramine dye, a spiropirane dye or an indolinophthalide dye is pref. used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with excellent image stability.

[Conventional technology]

Usually, heat-sensitive recording materials that utilize a heated color-forming reaction between a colorless or light-colored electron-donating colorless dye (leuco dye) and an electron-accepting compound (developer) such as a phenol or an organic acid are disclosed in Japanese Patent Publication No. 43-4160. , Japanese Patent Publication No. 45-14039, Japanese Patent Application Laid-Open No. 48-27736, etc., and it has been widely put into practical use.

Generally, heat-sensitive recording sheets are made by pulverizing and dispersing a leuco dye and a color developer such as a phenolic substance into fine particles, then mixing the two and adding a binder, filler, sensitivity improver, lubricant, and other auxiliaries. The resulting coating liquid is applied to a support such as paper or film, and color recording is obtained through an instantaneous chemical reaction caused by heating.

A thermal printer, a facsimile machine, etc. having a built-in thermal head is used to heat such a heat-sensitive recording material to develop color. Compared to other recording materials, such recording materials can produce records in a relatively short time without complicated processes such as phenomenon and fixing, do not generate noise, and are relatively inexpensive. Due to these advantages, it is widely used not only for copying books and documents, but also for information such as electronic computers, facsimiles, telex, medical equipment, measuring instruments, and bar code labels.

The phenolic properties used in these heat-sensitive recording materials include 2,2'-bis(4'-hydroxyphenyl)propane, 4,4'-benzyloxy-4-hydroxyphenylsulfone, and 1,1-bis(4-hydroxyphenyl)propane. Many examples have been proposed, including hydroxyphenyl)cyclohexane and 1,7(bis-pyhydroxyphenylthio)-3,5-dioxahebutane.

However, heat-sensitive recording materials using these phenolic color developers have the disadvantage that when the color developing portion comes into contact with oil or plasticizer, the density decreases or the color disappears.

In addition, in order to improve the stability of images,
No. 4793 and JP-A-59-14989 disclose methods using phosphorous esters and phosphoric esters, but at present the stability of images against water and oil is not sufficient.

On the other hand, as an improvement on these points in conventional heat-sensitive recording materials, a material in which a water-soluble polymer overcoat layer is provided on the heat-sensitive coloring layer has been proposed. This has the disadvantage of impeding conduction, resulting in poor thermal sensitivity and high cost.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which overcomes the drawbacks of the prior art and has excellent oil resistance, in particular, in which the density of the color developing area is not reduced by oil.

[Means to solve the problem]

According to the invention, in a heat-sensitive recording material comprising an electron-donating colorless dye and an electron-accepting compound.

There is provided a heat-sensitive recording material characterized in that a compound represented by the following general formula is used as the electron-accepting compound.

However, in the formula, R is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group, or an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. group, n is 2 or 3
represents.

By using the above-mentioned phenolic compound as an electron-accepting compound, the heat-sensitive recording material of the present invention has excellent color development sensitivity and is suitable for high-speed recording.Moreover, the density of the color development area is not reduced by oil, so-called It has excellent oil resistance.

Specific examples of the phenolic compound used in the present invention are shown below, but the present invention is not limited thereto.

Compound blood structure (1) (H○-◎-5C, H4 carbon dioxide p=.

(2) (H○-◎-5C, H, ObenP=○ Electron-donating colorless dye (leuco dye) used in the present invention
These dyes may be applied singly or in a mixture of two or more types, and as such dyes, those applied to this type of recording material may be arbitrarily applied, such as triphenylmethane-based, fluoran-based, phenothiazine-based dyes, etc. Leuco compounds of dyes such as , auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. Specific examples of such dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(p-dimethyl (aminophenyl)-6-diethylaminophenyl.

3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5, 7-dimethylfluorane, 3
-(N-methyl-N-isobutylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluorane, 3-diethylamino -7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-
6-Methyl-7-chlorofluorane.

3-(N-ρ-tri-N-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoran) methylphenyl)amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-
chloranilino)xantylbenzoic acid lactam), 3-
Diethylamino-6-methyl-7-(m-hlichloromethylanilino)fluoran, 3-diethylamino-7-(0-chloroanilino)fluoran.

3-Dibutylamino-7-(o-chloroanilino)fluoran.

3-N-methyl-N-7mylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-(2',4'-
dimethylanilino) pullolan, 3-(N,N-diethylamino)-5-methyl-7-(
N,N-dibenzylamino)fluorane, benzoylleucomethylene blue 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-31-methoxy-benzoindolino-pyrylosvirane, 3-(2'- Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide.

3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3- (2'-methoxy-5'-methylphenyl)phthalide, 3=(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N -benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-P-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran.

3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-( α-phenylethylamino 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3.6-bis (dimethylamino)fluorene spiro(9
,3')-6'-dimethylaminophthalide, 3-(N-
benzyl-N-cyclohexylamino)-5,6-penzo-7-α-naphthylamino-4'bromofluorane, 3-diethylamino-6-chloro-7-anilinopluorane, 3-N-ethyl-N- (2-ethoxypropyl)amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino 4',5'-benzofluorane, 3-(p-dimethylaminophenyl)-3-(1,1-
Bis(p-dimethylaminophenyl)ethylene-2-yl)phthalide, 3-(P-dimethylaminophenyl)-3-(1,1-
Bis(P~dimethylaminophenyl)ethylene-2-yl)-6=dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-(1-p-
Dimethylaminophenylethylene-2-yl)phthalide.

3-(p-dimethylaminophenyl)-3-(1-p-
dimethylaminophenyl-1-ρ-chlorophenylethylene-2-yl)-6-dimethylaminophthalide, 3-
(4'-dimethylamino-2'-methoxy)-3-(1
"-p-dimethylaminophenyl-1z'-P-chlorophenyl-1//, 3LI-butadien-4"-yl)
Benzophthalide, 3-(4'-dimethylamino-2'
-benzyloxy)-3-(1''-p-dimethylaminophenyl-1''-phenyl-1''.

3″-butadien-4″-yl)benzophthalide, 3-
Dimethylamino-6-dimethylamino-fluorene-9
-spiro-3'-(6'-dimethylamino)phthalide, 3.3-bis(2-(p-dimethylaminophenyl)
-2-(p-methoxyphenyl)ethynyl)-4,5,
6,7-titrachlorophthalide, 3-bis(1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl)-5,6-dichloro-4,7-dibromophthalide, bis(p- dimethylaminostyryl)-1-naphthalenesulfonylmethane, etc.

Further, in the present invention, a phenolic compound represented by the above general formula is used as an electron-accepting compound, but if necessary, other electron-accepting compounds such as a phenolic compound, a thiophenolic compound, a thiourea derivative,
Organic acids, metal salts thereof, etc. can be used in combination, and specific examples include those shown below.

4.4'-isopropylidene bisphenol, 4.4
′ -isopropylidene bis(0-methylphenol)
.

4.4'-Secondary-butylidenebisphenol, 4.4'-Isopropylidenebis(2-tertiary-
butylphenol), 4.4'-cyclohexylidene diphenol, 4.4
′ -isopropylidene bis(2-chlorophenol)
, 2.2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-methylenebis(4-ethyl-6-tert-butylphenol), 4.4'-butylidenebis(6-tert-butyl- 2-methylphenol), 1.1.3-tris(2-methyl-4-hydroxy-5
-tert-butylphenyl)butane, 1.1.3-
Tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4,4'-thiobis(6-tert-butyl-2-
methylphenol), 4,4'-diphenolsulfone.

4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-41-hydroxydiphenylsulfone, 4.4'-diphenolsulfoxide, isopropyl -P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, Stearyl gallate, lauryl gallate, octyl gallate, 1.3-bis(4-hydroxyphenylthio)-propane, 1.3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'- Diphenylthiourea, N,N'-di(m-chlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide, bis-(4-hydroxyphenyl)acetic acid methyl ester, bis-(4-hydroxyphenyl)acetic acid benzyl ester Ester, 1.3-bis(4-hydroxycumyl)benzene, 1.
4-bis(4-hydroxycumyl)benzene, 2.4'
-diphenolsulfone, 2,2'-diallyl-4,4'-diphenolsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, zinc 1-acetyloxy-2-naphthoate.

Zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α,α-bis(4-hydroxyphenyl)-α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A , tetrabromobisphenol S, 3,4-dihydroxy-4'-methyldiphenylsulfone, etc.

In order to produce the heat-sensitive recording material of the present invention, an electron-donating colorless dye, an electron-accepting compound, and auxiliary components may be bonded and supported on a support. As the binder in this case, various commonly used binders can be used as appropriate, and specific examples include the following.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic In addition to water-soluble polymers such as acid ternary copolymers, styrene/maleic anhydride copolymer alkali salts, isobutylene/maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate , polyurethane, polyacrylate, polymethacrylate.

Emulsions such as vinyl chloride/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, and latex such as styrene/butadiene copolymers and styrene/butadiene/acrylic copolymers.

Furthermore, when obtaining a heat-sensitive recording material according to the present invention, various heat-fusible substances can be used as a heat sensitivity improver, if necessary, and specific examples thereof include the following compounds.

Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, ρ- Benzyl biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, ■-methyl hydroxy-2-naphthoic acid ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester,
1,4-dimethoxynaphthalene, 1,4-jethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,
2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, 1,4-bis(phenoxy)butane, 1,4-bis( phenoxy)-2-butene, 1,2-
Bis(4-methoxyphenylthio)ethane, dibenzoylmethane, 1,4-bis(phenylthio)butane, 1,
4-bis(phenylthio)-2-butene, 1,2-bis(4-methoxyphenylthio)ethane, l,3-bis(
2-vinyloxyethoxy)benzene, 1,4-bis(
2-vinyloxyethoxy)benzene, p-(2-vinyloxyethoxy)biphenyl, P-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, (,3-dibenzoyloxypropane, dibenzyl disulfide, 1.1-diphenylethanol, 1.1-diphenylpropatol, p-(benzyloxy)benzyl alcohol, 1,3-diphenoxy-2-propatol, N-octadecylcarbamoyl-P-methoxycarbonylbenzene, N-octadecylcarbamoyl Benzene et al.

In addition, when obtaining a heat-sensitive recording material according to the present invention, in addition to the electron-donating colorless dye and the electron-accepting compound, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers and surfactants, may be added as necessary. Agents etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders.

〔Effect of the invention〕

Since the heat-sensitive recording material of the present invention uses the compound represented by the above general formula as an electron-accepting compound, it has excellent oil resistance in the image area.

〔Example〕

Examples of the present invention are shown below. Note that parts and 2 represent parts by weight and weight 2, respectively.

Example 1 [Liquid A], [Liquid B], and [Liquid C] were prepared by separately pulverizing and dispersing mixtures having the following compositions for two days using a magnetic ball mill.

[Liquid A]

10% polyvinyl alcohol aqueous solution 20 parts water [Liquid B] 60 parts polyvinyl alcohol 10% aqueous solution 20 parts water
60 parts [Liquid C] Calcium carbonate 80 parts Zinc stearate 20 parts Polyvinyl alcohol 10% aqueous solution 100 parts Water
300 parts or more of (A3-[C] solution obtained as [A solution]: [
A heat-sensitive coating solution was prepared by mixing B solution]:[C solution]=1:3:5, and the dry weight was 4 to 5 g/IT! on high-quality paper with a basis weight of 52 g/rrr. After coating and drying, the heat-sensitive recording material of the present invention was prepared by calendering to obtain a Bekk smoothness of 500 to 3000 seconds.

Example 2 The thermosensitive material of Example 2 was prepared in the same manner as in Example 1, except that tri(4-hydroxyphenylthiopropyl) phosphoric acid was used instead of tri(4-hydroxyphenylthioethyl) phosphoric acid in Solution B. Created recording materials.

Example 3 In Example 1, tri(3-chloro-
A heat-sensitive recording material of Example 3 was prepared in the same manner except that 4-hydroxyphenylthioethyl) phosphoric acid was used.

Example 4 Same procedure as in Example 1 except that tri(3-methoxy-4-hydroxyphenylthioethyl) phosphoric acid was used instead of tri(4-hydroxyphenylthioethyl) phosphoric acid in [Liquid B]. A thermosensitive recording material of Example 4 was prepared.

Comparative Example 1 In Example 1, 2,2-bis(4-hydroxyphenylthioethyl)phosphoric acid in [Liquid B] was replaced with
A heat-sensitive recording material of Comparative Example 1 was prepared in the same manner except that -hydroxyphenyl)propane was used.

Comparative Example 2 In Example 1, 1,7-bis(
A heat-sensitive recording material of Comparative Example 2 was prepared in the same manner except that p-hydroxyphenylthio)3,5-dioxahebutane was used.

The following tests were conducted on the heat-sensitive recording material prepared as described above. The results are shown in Table-1.

Color development: When color was developed at 150° C. using a thermal gradient tester, the density of the colored area was measured using a Macbeth densitometer.

Oil resistance: Cottonseed oil was applied to a recording material that had been colored at 150°C using a heat gradient tester, and the density of the colored area was measured using a Macbeth densitometer after 16 hours under test conditions at 40°C.

From the above results, it is clear that the heat-sensitive recording material of the present invention has excellent oil resistance of images.

Claims (1)

[Claims] (1) A thermosensitive recording material comprising an electron-donating colorless dye and an electron-accepting compound, characterized in that a compound represented by the following general formula is used as the electron-accepting compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and n represents 2 or 3.)