JP2694219B2 - Thermal recording medium - Google Patents

Description

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material which is excellent in high-speed recording suitability and storability of a recorded image, and which does not cause a decrease in whiteness of a white paper portion. It is about.

"Prior Art" Conventionally, a thermosensitive recording medium has been used which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to bring both color-forming substances into contact with each other by heat to obtain a recorded image. Well known.

Recently, with the remarkable progress of the thermal recording method, it is possible to increase the speed of thermal fax, thermal printer, etc.
With a thermal fax, recording speeds of 20 seconds or more are possible with an A4 size, and with a thermal printer, recording speeds of 120 characters / sec or more are possible. As described above, with the increase in speed in the hardware field, there is a demand for a heat-sensitive recording medium to be used which is excellent in high-speed recording suitability.

"Problems to be solved by the invention" However, in order to enable high-speed recording, it is necessary to increase the sensitivity of the thermosensitive recording medium. Generally, the higher the sensitivity of the recording medium, the more the white portion is discolored (fog phenomenon) due to long-term storage. It tends to occur easily. Also, the storage stability of the recorded image is not sufficient.

In view of such a current situation, the present inventors have earnestly studied for improvement of such defects observed in a thermal recording material, and as a result, when at least one compound represented by the general formula [I] is used as a color developing agent, It was found that a heated recording material having high whiteness, excellent suitability for high-speed recording and storability of recorded images, and having no deterioration in whiteness even when stored for a long period of time can be obtained, and completed the present invention. It was

[Means for Solving the Problems] The present invention provides a thermosensitive recording medium that utilizes the reaction between a colorless or light-colored basic dye and a color-forming agent that can be colored by contact with the basic dye. As a coloring agent, the following general formula [I]
A heat-sensitive recording material comprising at least one compound represented by

[In the formula, R represents an alkylene group having at least one ester bond in the main chain. R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. [Action] The reason why the compound represented by the general formula [I] gives a recording material which is free from the fog phenomenon and has excellent high-speed recording suitability and recorded image storability is not necessarily clear. Since the compound having the structure of] does not dissolve in water, the fog phenomenon does not occur even if the recording medium is stored in a high humidity environment,
It has a high melting point because it has an appropriate melting point, and it is presumed that the fog phenomenon does not occur even when the recording material is stored in a high temperature environment.

Specific examples of the compound represented by the general formula [I] include (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester and (4-hydroxyphenylthio) acetic acid-3- ( 4-hydroxyphenylthio) propyl ester, (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) propyl ester, (4-hydroxyphenylthio) acetic acid-1-methyl-2
-(4-hydroxyphenylthio) ethyl ester, (4-hydroxyphenylthio) acetic acid-4- (4-hydroxyphenylthio) butyl ester, (4-hydroxyphenylthio) acetic acid-2- (4-hydroxy-3-) Methylphenylthio) ethyl ester, (4-hydroxy-3-methylphenylthio) acetic acid-2
-(4-hydroxyphenylthio) ethyl ester, (4-hydroxy-3-methylphenylthio) acetic acid-2
-(4-Hydroxy-3-methylphenylthio) ethyl ester, (4-hydroxy-3-methylphenylthio) acetic acid-3
-(4-hydroxy-3-methylphenylthio) propyl ester, (4-hydroxy-3-methoxyphenylthio) acetic acid-
2- (4-hydroxy-3-methoxyphenylthio) ethyl ester, (4-hydroxy-3-methoxyphenylthio) acetic acid-
3- (4-hydroxy-3-methoxyphenylthio) propyl ester, (4-hydroxy-3-allylphenylthio) acetic acid-2
-(4-Hydroxy-3-allylphenylthio) ethyl ester, (4-hydroxy-3-chlorophenylthio) acetic acid-2
-(4-Hydroxy-3-chlorophenylthio) ethyl ester, (4-hydroxy-3-chlorophenylthio) acetic acid-3
-(4-hydroxy-3-chlorophenylthio) propyl ester, (4-hydroxy-3-cyclohexylphenylthio)
Acetic acid-2- (4-hydroxy-3-cyclohexylphenylthio) ethyl ester, (3,4-dihydroxyphenylthio) acetic acid-2- (3,4-
Dihydroxyphenylthio) ethyl ester, (3,4-dihydroxyphenylthio) acetic acid-3- (3,4-
(Dihydroxyphenylthio) propyl ester, (4-hydroxyphenylthio) acetic acid-2- (2-hydroxyphenylthio) ethyl ester, (2-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester, 2-Hydroxyphenylthio) acetic acid-2- (2-hydroxyphenylthio) ethyl ester, 2- (4-hydroxyphenylthio) propionic acid-2
-(4-hydroxyphenylthio) ethyl ester, 2- (4-hydroxyphenylthio) propionic acid-3
-(4-hydroxyphenylthio) propyl ester, 2- (4-hydroxy-3-methylphenylthio) propionic acid-2- (4-hydroxy-3-methylphenylthio) ethyl ester, 2- (4-hydroxy-) 3-Methylphenylthio) propionic acid-3- (4-hydroxy-3-methylphenylthio) propyl ester, 2- (4-hydroxy-3-methoxyphenylthio) propionic acid-2- (4-hydroxy-3-) Methoxyphenylthio) ethyl ester, 2- (4-hydroxy-3-chlorophenylthio) propionic acid-2- (4-hydroxy-3-chlorophenylthio) ethyl ester, 2- (3,4-dihydroxyphenylthio) propionic acid -2- (3,4-dihydroxyphenylthio) ethyl ester, 3- (4-hydro) Shifeniruchio) propionic acid -2
-(4-hydroxyphenylthio) ethyl ester, 3- (4-hydroxyphenylthio) propionic acid-3
-(4-hydroxyphenylthio) propyl ester, 3- (4-hydroxy-3-methylphenylthio) propionic acid-2- (4-hydroxy-3-methylphenylthio) ethyl ester, 3- (4-hydroxy-) 3-Methoxyphenylthio) propionic acid-2- (4-hydroxy-3-methoxyphenylthio) ethyl ester, 3- (3,4-dihydroxyphenylthio) propionic acid-2- (3,4-dihydroxyphenylthio) Ethyl ester, oxalic acid bis [2- (4-hydroxyphenylthio) ethyl] ester, oxalic acid bis [2- (4-hydroxy-3-methylphenylthio) ethyl] ester, oxalic acid bis [2- (4- Hydroxy-3-cyclohexylphenylthio) ethyl] ester, oxalic acid bis [2- (4-hydroxy) Si-3-chlorophenylthio) ethyl] ester, oxalic acid bis [2- (4-hydroxy-3-allylphenylthio) ethyl] ester, oxalic acid bis [2- (3,4-dihydroxyphenylthio) ethyl] ester , Malonic acid bis [2- (4-hydroxyphenylthio) ethyl] ester, malonic acid bis [2- (4-hydroxy-3-methoxyphenylthio) ethyl] ester, malonic acid bis [2- (4-hydroxy- 3-chlorophenylthio) ethyl] ester, succinic acid bis [2- (4-hydroxyphenylthio) ethyl] ester, succinic acid bis [2- (4-hydroxy-3-methylphenylthio) ethyl] ester, succinic acid bis [2- (4-hydroxy-3-methoxyphenylthio) ethyl] ester, glutaric acid bis [2- 4-hydroxyphenyl-thio)
Ethyl] ester, ethylene glycol bis [(4-hydroxyphenylthio) acetate], ethylene glycol bis [3- (4-hydroxyphenylthio) propionate], ethylene glycol bis [(4-hydroxy-3-methylphenylthio) acetate ], Ethylene glycol bis [3- (4-hydroxy-3)
-Methylphenylthio) propionate], ethylene glycol bis [(4-hydroxy-3-methoxyphenylthio) acetate], ethylene glycol bis [3- (4-hydroxy-3)
-Methoxyphenylthio) propionate], ethylene glycol bis [(4-hydroxy-3-chlorophenylthio) acetate], ethylene glycol bis [3- (4-hydroxy-3)
-Chlorophenylthio) propionate], propylene glycol bis [(4-hydroxyphenylthio) acetate], propylene glycol bis [3- (4-hydroxyphenylthio) propionate], propylene glycol bis [(4-hydroxy-3-)
Cyclohexylphenylthio) acetate], propylene glycol bis [3- (4-hydroxy-
3-cyclohexylphenylthio) propionate], 1,3-propanediol bis [(4-hydroxyphenylthio) acetate], 1,3-propanediol bis [3- (4-hydroxyphenylthio) propionate], 1,3 -Propanediol bis [(4-hydroxy-3
-Allylphenylthio) acetate], 1,3-propanediol bis [3- (4-hydroxy-3-allylphenylthio) propionate], 1,3-propanediol bis [(4-hydroxy-3
-Ethoxyphenylthio) acetate], 1,3-propanediol bis [3- (4-hydroxy-3-ethoxyphenylthio) propionate], 1,4-butanediol bis [(4-hydroxyphenylthio) acetate], 1,4-butanediol bis [3- (4-hydroxyphenylthio) propionate], 1,4-butanediol bis [(4-hydroxy-3-
Methylphenylthio) acetate], 1,4-butanediol bis [3- (4-hydroxy-
3-Methylphenylthio) propionate], 1,4-butanediol bis [(4-hydroxy-3-
Chlorophenylthio) acetate], 1,4-butanediol bis [3- (4-hydroxy-
3-chlorophenylthio) propionate], 1,4-butanediol bis [(4-hydroxy-3-
Methoxyphenylthio) acetate], 1,4-butanediol bis [3- (4-hydroxy-
3-methoxyphenylthio) propionate], carbonic acid bis [2- (4-hydroxyphenylthio) ethyl] ester, carbonic acid bis [2- (4-hydroxy-3-chlorophenylthio) ethyl] ester, carbonic acid bis [2- ( 4-hydroxy-3-methoxyphenylthio) ethyl] ester, carbonic acid bis [2- (4-hydroxy-3-allylphenylthio) ethyl] ester, and the like. Of course, two or more of these compounds can be used in combination.

Among the compounds represented by the general formula [I], R is -X ₁ -COO-X _2- , -X ₁ -OOC-X ₃ -COO-X _2- , -X ₁ -COO-X ₄ -OOC A compound which is -X ₂ -or -X ₁ -OCOO-X ₂ -is particularly preferable because it gives a recording material free from color development and fog phenomenon in the white paper portion, and R is -X.
_{The 1-} COO-X ₂ -compound is more preferably used because it is relatively easy to synthesize and the light-preserving property of recorded images is excellent. However, X ₁ , X ₂ , and X ₄ each represent an alkylene group, and X ₃
Represents a direct bond or an alkylene group.

Further, among the compounds represented by the general formula [I], those having a melting point of 50 ° C. or higher are preferable, and those having a melting point of 70 ° C. to 200 ° C. are particularly preferable.

In the present invention, various types of colorless or light-colored basic dyes constituting the recording layer of the thermosensitive recording medium are known, and examples thereof include the following. 3,3-bis (p-
Dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (4-
Dimethylamino-2-methylphenyl) -6- (dimethylamino) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylamino) Phenyl) -3-
(2-Methylindol-3-ylphthalide, 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) -6-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide,
Triallylmethane dyes such as -p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydryl benzyl ether, N -Halophenyl-
Diphenylmethane dyes such as leuco auramine and N-2,4,5-trichlorophenyl leuco auramine, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-
2-yl] -4,5,6,7-tetrabromophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4 , 5,6,7−
Tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, etc. Divinylphthalide dyes, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and other thiazine dyes, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl- Spiro-
Spiro dyes such as dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o- Lactam dyes such as chloroanilino) lactam, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3
-Diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluoran, 3- (N-
Ethyl-p-toluidino) -7-methylfluoran, 3
-Diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-N-methyl -N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 4-benzylamino-8-diethylamino-benzo [a] Fluorane, 3- [4- (4-dimethylaminoanilino) anilino] -7-chloro-6-methylfluorane, 8- [4- (4-dimethylaminoanilino) anilino] -benzo [a] fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluorane, 3- Ethyl-p-N-toluidino) -6
-Methyl-7- (p-toluidino) fluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- ( 2-carbomethoxy-phenylamino) fluorane, 3- (N
-Ethyl-N-isoamylamino) -6-methyl-7-
Phenylaminofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6 -Methyl-
7-phenylaminofluoran, 3-diethylamino-
6-methyl-7-xylidinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-dibutylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-N-tetrahydro) Furfurylamino) -6-methyl-7-phenylaminofluorane, 3- (N-methyl-Nn-propylamino) -6-methyl-7-phenylaminofluorane,
3- (N-ethyl-N-i-butylamino) -6-methyl-7-phenylaminofluorane, 3- (N-methyl-Nn-hexylamino) -6-methyl-7-phenylaminofluor Oran, 3- (N-ethyl-N-n-hexylamino) -6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-cyclopentylamino)
Fluorane dyes such as -6-methyl-7-phenylaminofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3-diethylamino-6- (N-allyl-N-methylaminofluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,6-bis (dimethylamino) -spiro [fluorene-9,6'-6'H- Chromeno (4,3-b) indole], 3,6-bis (dimethylamino) -3'-methyl-spiro [fluorene-9,6'-
6'H-chromeno (4,3-b) indole], 3,6-bis (diethylamino) -3'-methyl-spiro [fluorene-9,6'-6'H-chromeno (4,3-b) Indole)
Fluorene dyes and the like. Of course, it is not limited to these dyes, and two or more dyes can be used in combination.

Incidentally, the combined ratio of the colorant and the basic dye having the specific structure is not necessarily limited, but 100 to 700 parts by weight, more preferably 150 to 600 parts by weight with respect to 100 parts by weight of the basic dye. A part by weight of a coloring agent is blended.

The coating liquid containing these is generally prepared by dispersing water and a coloring agent together or separately by using water as a dispersion medium and a stirring and crushing machine such as a ball mill, an attritor, and a sand grinder.

In such a coating solution, usually as a binder starches, hydroxyethylcellulose, methylcellulose,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, etc. %, Preferably about 15 to 30% by weight.

Further, various auxiliary agents may be added to the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium salt of lauryl alcohol sulfate, dispersant such as fatty acid metal salt, triazole type. And other ultraviolet absorbers, defoamers, fluorescent dyes, coloring dyes and the like. In addition, a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. in the paint so that the thermal recording material does not stick when it comes into contact with the recording equipment or recording head. Can also be added.

In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, and activated clay can be added to improve the adhesion of dust to the recording head.

Further, for the purpose of further increasing recording sensitivity, various known heat-fusible substances can be used in combination within a range that does not impair the desired effect of the present invention. Specific examples of preferable heat-fusible substances include compounds represented by the following general formulas [II] to [VIII].

[In the formula, R represents a divalent group having 2 to 8 carbon atoms, preferably an alkylene group, an alkylene group having a carbonyl group,
An alkylene group having a halogen atom, an alkylene group having an ether bond, an alkylene group having a thioether bond, an alkylene group having an ester bond, an alkylene group having an amide bond, an alkylene group having an unsaturated bond, more preferably an alkylene group Represents an alkylene group having an ether bond. R _{1 to} R ₄ are each a hydrogen atom, a lower alkyl group, a cycloalkyl group, a phenyl group,
Lower alkoxyl group, cycloalkoxyl group, lower alkylthio group, aralkyloxy group, aralkylthio group,
A lower alkyloxycarbonyl group, an aralkyloxycarbonyl group, or a halogen atom is shown. Also, R ₁ and R ₂ ,
R ₃ and R ₄ may combine with each other to form an aromatic ring.

X and Y each represent an oxygen atom or a sulfur atom. ] [In the formula, R ₅ , R ₈ and R ₉ each represent an alkyl group which may have a substituent, an aryl group which may have a substituent, or an aralkyl group which may have a substituent, and preferably Has 1 carbon
An alkyl group of 24; a lower alkyl group, a lower alkoxyl group, a halogen atom, a lower alkyloxycarbonyl group, a phenyl group which may have an aralkyloxycarbonyl group as a substituent; a lower alkyl group, a lower alkoxyl group as a substituent, A benzyl group which may have a halogen atom, a lower alkyloxycarbonyl group or an aralkyloxycarbonyl group is shown.

R ₆ and R ₇ each represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group, an aralkyloxy group, a lower alkyloxycarbonyl group, an aralkyloxycarbonyl group, R ₁₀ represents a hydrogen atom or a hydroxyl group, and R ₁₁
Represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkyloxycarbonyl group, or an aralkyloxycarbonyl group.

R ₁₂ represents an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, and R ₁₃ and R ₁₄ each represent a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, or an alkenyl group having 2 to 24 carbon atoms. , a phenyl group, a R _15, R ₁₆ are each a lower alkyl group as a substituent, a lower alkoxyl group, a benzyl group which may have a halogen atom. Among the heat-fusible substances represented by the general formulas [II] to [VIII], those having a melting point of 60 to 200 ° C. are preferable, and compounds having a melting point of 70 to 150 ° C. are more preferable.

Specific examples of these compounds include the following.

1,2-diphenoxyethane, 1,2-bis (2-methylphenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1-phenoxy -2- (2-methylphenoxy) ethane, 1-phenoxy-2- (3-methylphenoxy)
Ethane, 1-phenoxy-2- (4-methylphenoxy) ethane, 1-phenoxy-2- (4-ethylphenoxy) ethane, 1-phenoxy-2- (4-isopropylphenoxy) ethane, 1-phenoxy-2- (4-te
rt-Butylphenoxy) ethane, 1-phenoxy-2-
(2,3-Dimethylphenoxy) ethane, 1-phenoxy-2- (2,4-dimethylphenoxy) ethane, 1-phenoxy-2- (3,4-dimethylphenoxy) ethane, 1
-Phenoxy-2- (3,5-dimethylphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methylphenoxy) ethane, 1- (3-methylphenoxy)-
2- (4-methylphenoxy) ethane, 1-phenoxy-2- (2-phenylphenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane, 1-
(2-Methylphenoxy) -2- (4-methoxyphenoxy) ethane, 1- (2-chlorophenoxy) -2-
(4-Methoxyphenoxy) ethane, 1- (3-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 1- (4-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 1- (2 , 4-Dimethylphenoxy) -2- (4-methoxyphenoxy) ethane, 1-phenoxy-2- (α-naphthyloxy) ethane, 1-phenoxy-2- (2-chlorophenoxy) ethane, 1-
Phenoxy-2- (3-chlorophenoxy) ethane, 1
Phenoxy-2- (4-chlorophenoxy) ethane,
1,2-bis (2-chlorophenoxy) ethane, 1,2-bis (3-chlorophenoxy) ethane, 1,2-bis (4-chlorophenoxy) ethane, 1,3-bis (4-methoxyphenoxy) Propane, 1-phenoxy-3- (β-naphthyloxy) propane, 1- (4-methylphenoxy)
-3- (β-naphthyloxy) propane, 1-phenoxy-3- (4-phenylphenoxy) propane, 1-
(4-Methylphenoxy) -3- (4-phenylphenoxy) propane, 1,4-diphenoxybutane, 1,4-bis (4-methylphenoxy) butane, 1,4-bis (4-methoxyphenoxy) butane 1,4-bis (4-cyclohexylphenoxy) butane, 1,4-bis (4-chlorophenoxy) butane, 1,4-bis (2-methylphenoxy) butane, 1,6-diphenoxyhexane, 1- Phenoxy-6- (β-naphthyloxy) hexane, 1,2-bis [4- (methylthio) phenoxy] ethane, 1,3-bis [4- (methylthio) phenoxy] propane, 1,4-
Bis [4- (methylthio) phenoxy] butane, 1,2-
Bis [4- (benzylthio) phenoxy] ethane, 1,2
-Bis (4-benzyloxyphenoxy) ethane, 1,2
-Bis (4-methoxycarbonylphenoxy) ethane,
1,2-bis (4-ethoxycarbonylphenoxy) ethane, 1,2-bis (4-benzyloxycarbonylphenoxy) ethane, 1,5-bis (4-methoxyphenoxy)
-3-Oxapentane, 1,5-bis [4- (methylthio) phenoxy] -3-oxapentane, 1,5-bis (4-methoxyphenoxy) -3-thiapentane, 1,5
-Bis [4- (methylthio) phenoxy] -3-thiapentane, 1,3-diphenoxyacetone, 1,3-diphenoxy-2-hydroxypropane, 1,3-diphenoxy-2
-Chloropropane, 1,4-diphenoxy-2-chlorobutane, 1,4-diphenoxy-2-butene, 1,4-diphenoxy-2-butyne, phenoxyacetic acid-2-phenoxyethyl ester, 1-phenoxy-N- (2 -Phenoxyethyl) acetamide, 1-phenoxy-N- (3-phenoxypropyl) acetamide, 1,2-bis (phenylthio) ethane, 1,3-bis (phenylthio) propane, 1,4-bis (phenylthio) butane, 1,2-bis (4
-Chlorophenylthio) ethane, 1,3-bis (4-chlorophenylthio) propane, 1,4-bis (4-chlorophenylthio) butane, 1,2-bis (4-methylphenylthio) ethane, 1,3- Bis (4-methylphenylthio)
Propane, 1,4-bis (4-methylphenylthio) butane, 1,2-bis (4-methoxyphenylthio) ethane,
1,3-bis (4-methoxyphenylthio) propane, 1,4
-Bis (4-methoxyphenylthio) butane, 1,5-bis (4-methoxyphenylthio) -3-oxapentane, 1,3-bis (phenylthio) acetone, 1-phenoxy-2- (phenylthio) ethane, 1-phenoxy
4- (phenylthio) butane, 1-phenoxy-2-
(4-methylphenylthio) ethane, 1-phenoxy-
2- (4-chlorophenylthio) ethane, 1-phenoxy-2- (4-methoxyphenylthio) ethane; dimethyl isophthalate, dimethyl terephthalate, dibenzyl isophthalate, dibenzyl terephthalate, p-benzyloxybenzoic acid methyl ester, p-benzyloxybenzoic acid benzyl ester, 4- (p-chlorobenzyloxy) benzoic acid-p-chlorobenzyl ester, 4
-(P-Methylbenzyloxy) benzoic acid-p-methylbenzyl ester; 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 2- (p-chlorobenzyloxy) naphthalene, 2- (p-methylbenzyloxy) naphthalene Two
-(P-Methoxybenzyloxy) naphthalene, 2-dodecyloxynaphthalene; 6-benzyloxy-2-naphthoic acid benzyl ester, 4-benzyloxy-1-naphthoic acid benzyl ester, 1-hydroxy-2-naphthoic acid phenyl ester , 2-naphthoic acid phenyl ester; 1,2-bis (2-vinyloxyethoxy) benzene, 1,4
-Bis (2-vinyloxyethoxy) benzene, 2,5-
Bis (2-vinyloxyethoxy) toluene, 3,5-bis (2-vinyloxyethoxy) toluene, 1-tert-butyl-2,5-bis (2-vinyloxyethoxy) benzene, 1,4-di- tert-butyl-2,5-bis (2-vinyloxyethoxy) benzene; caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, N
-Methylstearic acid amide, stearic acid anilide,
N-methyl oleic acid amide, N-ethyl capric acid amide, linoleic acid anilide, benzanilide, N-butyl lauric acid amide, N-octadecyl atceamide,
N-oleinacetamide, N-oleylbenzamide, N-stearylcyclohexylamide; dibenzyl oxalate, bis (p-methylbenzyl) oxalate, bis (p-chlorobenzyl) oxalate and the like.

Of course, the compounds are not limited to these compounds, and two or more kinds may be used in combination as required.

The amount of these heat-fusible substances used is not particularly limited, but is 50 to 7 per 100 parts by weight of the basic dye.
It is desirable to use it in an amount of 00 parts by weight, preferably 100 to 500 parts by weight.

Further, in the present invention, the following general formula [IX] is contained in the thermosensitive recording layer.
The inclusion of at least one selected from the phenolic compounds represented by the formulas [X II] to (X II) is a preferable mode because the recorded image can be made more robust.

[In the formula, R ₁ is a branched alkyl group having 3 to 8 carbon atoms,
A cycloalkyl group, a phenyl group, or a halogen atom, R ₂ represents a hydrogen atom, a branched alkyl group having 3 to 8 carbon atoms, or a halogen atom, and R ₃ , R _{5 to} R ₈ each represent a hydrogen atom or a lower atom. Indicates an alkyl group. R ₄ represents a hydrogen atom, a halogen atom, or an alkyl group having 8 or less carbon atoms. X
Is -O -, - S -, - S-S -, - SO 2 - or And R ₉ and R ₁₀ each represent a hydrogen atom or an alkyl group having 8 or less carbon atoms. Further, R ₉ and R ₁₀ may be bonded to each other to form a ring. Z represents a linear or branched alkylene group having 8 or less carbon atoms. Specific examples of the compounds represented by the general formulas [IX] to [XII] include the following compounds.

4,4'-butylidene bis (2-tert-butyl-5-methylphenol) 4,4'-butylidene bis (2-tert-butyl-6-methylphenol), 4,4'-butylidene bis (2,6-di- tert-butylphenol), 4,4'-butylidenebis (2-cyclohexylphenol), 4,4'-
Butylidene bis (2-phenylphenol), 4,4'-
Cyclohexylidenebis (2-tert-butyl-5-methylphenol), 4,4'-Cyclohexylidenebis (2-ter
t-butyl-6-methylphenol), 4,4'-cyclohexylidenebis (2,6-di-tert-butylphenol), 4,4'-cyclohexylidenebis (2-cyclohexylphenol), 4,4 ′ -Cyclohexylidenebis (2-phenylphenol), 4,4′-thiobis (2-ter
t-butyl-5-methylphenol), 4,4'-thiobis (2-tert-butyl-6-methylphenol), 4,4'-
Thiobis (2,6-di-tert-butylphenol), 4,4 '
-Thiobis (2-cyclohexylphenol), 4,4 '
-Thiobis (2-phenylphenol), 4,4'-isopropylidenebis (2,6-dichlorophenol), 4,4 '
-Isopropylidene bis (2,6-dibromophenol), 4,4'-cyclohexylidene bis (2,6-dichlorophenol), 4,4'-cyclohexylidene bis (2,6-
Dibromophenol), bis (4-hydroxy-3,5-
Dichlorophenyl) sulfone, bis (4-hydroxy-
3,5-dibromophenyl) sulfone, bis (4-hydroxy-3,5-dichlorophenyl) sulfide, bis (4
-Hydroxy-3,5-dibromophenyl) sulfide,
Bis (4-hydroxy-3,5-dichlorophenyl) ether, bis (4-hydroxy-3,5-dibromophenyl) ether, bis (4-hydroxy-3,5-dichlorophenyl) disulfide, bis (4-hydroxy-3) ,Five
-Dibromophenyl) disulfide; 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-ter)
t-butylphenol), 2,2'-methylenebis (4,6-
Di-tert-butylphenol, 2,2'-methylenebis (4,6-dichlorophenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 2,2'-thiobis (4-methyl) −6-tert-Butylphenol), 2,2 ′
-Thiobis (4-ethyl-6-tert-butylphenol), 2,2'-thiobis (4,6-di-tert-butylphenol), 2,2'-dithiobis (4-methyl-6-tert-butylphenol), Bis (2-hydroxy-3-tert-butyl-5-methylphenyl) sulfone, bis (2-hydroxy-3-tert-butyl-5-ethylphenyl) sulfone, bis (2-hydroxy-3,5-dichlorophenyl)
Sulfone; 1,1,3-tris (2-methyl-4-hydroxy-5-tert
-Butylphenyl) butane, 1,1,3-tris (3-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (3,5-di-tert-butyl-4) -Hydroxyphenyl) butane, 1,1,3-tris (3,5-dichloro-4-hydroxyphenyl) butane, 1,1,3-tris (3,5-dibromo-4-hydroxyphenyl) butane,
1,1,3-tris (3-cyclohexyl-4-hydroxy-6-methylphenyl) butane, 1,1,3-tris (3-
Phenyl-4-hydroxyphenyl) butane, 2-methyl-1,1,3-tris (2-methyl-4-hydroxy-5-t
ert-butylphenyl) butane, 2-ethyl-1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-) Hydroxy-5-tert-butylphenyl) hexane, 1,1,3
-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) heptane, 2-ethyl-1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) hexane; 1 -[Bis (4-hydroxyphenyl) methyl] -3-
[1- (4-hydroxyphenyl) ethyl] benzene,
1- [bis (4-hydroxyphenyl) methyl] -4-
[1- (4-hydroxyphenyl) ethyl] benzene,
1- [bis (4-hydroxyphenyl) methyl] -3-
[1-Methyl-1- (4-hydroxyphenyl) ethyl] benzene, 1- [bis (4-hydroxyphenyl)]
Methyl] -4- [1-methyl-1- (4-hydroxyphenyl) ethyl] benzene, 1- [1,1-bis (4-hydroxyphenyl) ethyl] -3- [1- (4-hydroxyphenyl) Ethyl] benzene, 1- [1,1-bis (4-hydroxyphenyl) ethyl] -4- [1- (4
-Hydroxyphenyl) ethyl] benzene, 1- [1,1
-Bis (4-hydroxyphenyl) ethyl] -3- [1
-Methyl-1- (4-hydroxyphenyl) ethyl] benzene, 1- [1,1-bis (4-hydroxyphenyl)]
Ethyl] -4- [1-methyl-1- (4-hydroxyphenyl) ethyl] benzene and the like.

Of course, the compounds represented by the general formulas [IX] to [XII] as described above can be used in combination of two or more kinds.

The amount of the phenolic compound having these specific structures is not particularly limited, but it is preferably 5 to 300 parts by weight, preferably 100 parts by weight of the basic dye.
It is desirable to add about 10 to 200 parts by weight of a phenolic compound.

The heat-sensitive recording material of the present invention has an important feature in that at least one of the above-mentioned specific compounds is used as a color-developing agent, but bisphenol A, 4,4 'is used as long as the effect of the present invention is not impaired. -Cyclohexylidene diphenol, p-hydroxybenzoic acid benzyl ester, 4-
Various known colorants such as hydroxyphthalic acid dimethyl ester, 4-hydroxy-4′-isopropoxydiphenyl sulfone, and zinc thiocyanate antipyrine complex can be used in combination.

As the support, paper, plastic film, synthetic paper and the like are used, and paper is most preferably used in terms of price, suitability for application and the like. The coating amount of the coating liquid for forming the recording layer on the support is not particularly limited, and usually 2 to 12 by dry weight.
g / m ^2, it is preferably adjusted in the range of about 3 to 10 g / m ^2.

It is also possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer and the like. Of course, it is also possible to provide a protective layer on the back surface of the support or to provide an undercoat layer on the support. It is possible to add various known techniques in the thermal recording medium manufacturing field.

The heat-sensitive recording material of the present invention thus obtained has a high-speed recording suitability, has no tendency for discoloration of a recorded image or a fog phenomenon of a blank portion, and has excellent characteristics in terms of adhesion of residue (piling) to a recording head. It demonstrates.

"Examples" Examples are shown below to explain the present invention more specifically, but of course the present invention is not limited thereto. Unless otherwise specified, parts and% in examples are parts by weight and% by weight, respectively.

Example 1 Preparation of solution A 3- (N-ethyl-N-isoamylamino) -6-methyl-7-phenylaminofluorane 10 parts Methylcellulose 5% aqueous solution 10 parts Water 40 parts This composition was subjected to sand grinder to give an average particle diameter. Is 3 μm
And crushed until

Preparation of liquid B (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester 40 parts Methylcellulose 5% aqueous solution 40 parts Water 80 parts This composition was sand grinder to give an average particle size of 3 μm.
And crushed until

Recording layer formation 60 parts of liquid A, 160 parts of liquid B, silicon oxide pigment (oil absorption 180 ml / 1
00g) 30 parts, 20% oxidized starch aqueous solution 150 parts, and water 100 parts were mixed and stirred to prepare a coating liquid. The obtained coating liquid was applied to 50 g / m ² base paper so as to have a dry weight of 6.0 g / m ² and dried to obtain a thermosensitive recording paper.

Examples 2 to 11 In the same manner as in Example 1 except that the following compound was used in place of (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester in the preparation of solution B, 10 kinds were prepared. A heat sensitive recording paper was obtained.

Example 2; (4-hydroxyphenylthio) acetic acid-3-
(4-Hydroxyphenylthio) propyl ester Example 3; (4-Hydroxy-3-methoxyphenylthio) acetic acid-2- (4-hydroxy-3-methoxyphenylthio) ethyl ester Example 4; (4-Hydroxy- 3-chlorophenylthio)
Acetic acid-2- (4-hydroxy-3-chlorophenylthio) ethyl ester Example 5; 2- (4-Hydroxyphenylthio) propionic acid-2- (4-hydroxyphenylthio) ethyl ester Example 6; Oxalic acid bis [2- (4-Hydroxyphenylthio) ethyl] ester Example 7; Malonic acid bis [2- (4-hydroxyphenylthio) ethyl] ester Example 8; Ethylene glycol bis [(4-hydroxyphenylthio) acetate] Example 9; 1,3-Propanediol bis [(4-hydroxyphenylthio) acetate] Example 10; 1,4-Butanediol bis [(4-hydroxyphenylthio) acetate] Example 11; Biscarbonate [2] -(4-Hydroxyphenylthio) ethyl] ester Example 12 Preparation of Solution C 3-Dibutylamino-6-methyl-7-phen Luaminofluorane 10 parts 4,4'-butylidene bis (2-tert-butyl-5-methylphenol) 5 parts 1,2-bis (3-methylphenoxy) ethane 20 parts Methylcellulose 5% aqueous solution 25 parts water 100 parts The composition is sand grinder and the average particle size is 2 μm.
And crushed until

Formation of recording layer 80 parts of solution B prepared in the same manner as in Example 1 and solution 16 described above
0 part, 30 parts of silicon oxide pigment (oil absorption 180 ml / 100 g), 150 parts of 20% aqueous solution of oxidized starch and 80 parts of water were mixed and stirred to prepare a coating liquid. The obtained coating liquid was applied to a base paper of 50 g / m ² and the dry weight was 6.0 g / m ²
Was applied and dried to obtain a thermosensitive recording paper.

Examples 13 to 15 Three kinds were prepared in the same manner as in Example 12 except that the following compound was used in place of (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester in the preparation of solution B. A heat sensitive recording paper was obtained.

Example 13; (4-Hydroxy-3-methylphenylthio) acetic acid-2- (4-hydroxy-3-methylphenylthio) ethyl ester Example 14; (4-Hydroxy-3-methoxyphenylthio) acetic acid-2 -(4-Hydroxy-3-methoxyphenylthio) ethyl ester Example 15; (4-Hydroxy-3-allylphenylthio) acetic acid-2- (4-hydroxy-3-allylphenylthio) ethyl ester Examples 16- Seven kinds of thermal recording papers were obtained in the same manner as in Example 12 except that the following compound was used in place of 1,2-bis (3-methylphenoxy) ethane in the preparation of 22 C liquid.

Example 16; 1,3-bis (4-methoxyphenoxy) propane Example 17; Dibenzyl terephthalate Example 18; p-Benzyloxybenzoic acid benzyl ester Example 19; 2-Benzyloxynaphthalene Example 20; 1, 4-bis (2-vinyloxyethoxy) benzene Example 21; stearic acid amide Example 22; oxalic acid bis (p-methylbenzyl) ester Example 23 Preparation of solution D 3-dibutylamino-6-methyl-7-phenyl Aminofluorane 10 parts 1,2-bis (3-methylphenoxy) ethane 20 parts Methylcellulose 5% aqueous solution 25 parts Water 105 parts This composition has a mean particle size of 2 μm with a sand grinder.
And crushed until

Formation of recording layer 80 parts of solution B prepared in the same manner as in Example 1 and solution 16 described above
0 part, 30 parts of silicon oxide pigment (oil absorption 180 ml / 100 g), 150 parts of 20% aqueous solution of oxidized starch and 80 parts of water were mixed and stirred to prepare a coating liquid. The obtained coating liquid was applied to a base paper of 50 g / m ² and the dry weight was 6.0 g / m ²
Was applied and dried to obtain a thermosensitive recording paper.

Examples 24 to 26 Three kinds were prepared in the same manner as in Example 23 except that the following compound was used in place of (4-hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester in the preparation of solution B. A heat sensitive recording paper was obtained.

Example 24; (4-Hydroxy-3-methylphenylthio) acetic acid-2- (4-hydroxy-3-methylphenylthio) ethyl ester Example 25; (4-Hydroxy-3-methoxyphenylthio) acetic acid-2 -(4-Hydroxy-3-methoxyphenylthio) ethyl ester Example 26; (4-Hydroxy-3-allylphenylthio) acetic acid-2- (4-hydroxy-3-allylphenylthio) ethyl ester Comparative Examples 1- 2 In preparation of solution B, (4-hydroxyphenylthio)
Example 1 except that the following compound was used instead of acetic acid-2- (4-hydroxyphenylthio) ethyl ester.
Two types of thermal recording paper were obtained in the same manner as in.

Comparative Example 1; Bisphenol A Comparative Example 2; p-Hydroxybenzoic acid benzyl ester The 28 kinds of thermal recording papers thus obtained were recorded using a thermal facsimile (Hitachi HIFAX-700 type), and the density of the recorded image ( The color density) and the density of the blank area were measured with a Macbeth densitometer (RD-100R type, using an amber filter), and the results are shown in Table 1.

In addition, the density of the blank area and the recorded image after leaving the above recording paper under high temperature drying conditions of 60 ° C for 24 hours and under high humidity conditions of 40 ° C and 90% RH for 24 hours with a Macbeth densitometer Measure
Evaluate the storability of blank paper and the storability of records, and the results are first
It is shown in the table.

The whiteness of the surface of the recording layer before recording was measured with a Hunter whiteness meter, and the results are shown in Table 1.

[Effect] As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention was a recording medium having high whiteness, excellent high-speed recording characteristics, and excellent white paper storability and record storability.

Continuation of front page (56) Reference JP-A-60-248392 (JP, A) JP-A-63-249686 (JP, A) JP-A-60-222288 (JP, A) JP-A-59-165680 (JP , A) JP-A-60-112755 (JP, A) JP-A-62-181183 (JP, A)

Claims (2)

(57) [Claims] 1. A heat-sensitive recording material utilizing the reaction between a colorless or light-colored basic dye and a colorant which can be colored by contacting with the basic dye. ]
A thermosensitive recording medium comprising at least one compound represented by: [In the formula, R represents an alkylene group having at least one ester bond in the main chain. R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. ] 2. R is -X ₁ -COO-X _2- , -X ₁ -OOC-X ₃ -COO-X _2- , -X ₁ -COO-X ₄ -OOC-X _2- , or -X. ₁ -OCOO-X ₂ - is a claim (1) the heat-sensitive recording material according [X _1, X _2, X ₄ each represent an alkylene group, X ₃ represents a direct bond or an alkylene group].