JPH0741743B2 - Thermal recording - Google Patents

Description

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material containing a specific metal compound.

The thermosensitive recording medium is usually manufactured by applying a colorless or light-colored color-forming substance and a developer in a separated state together with a sensitizer, a binder and other additives to the surface of the base paper. Then, in the recording apparatus, when a heating element such as a thermal head or a heating pen comes into contact with the recording body, the dye and the color developer react with each other to develop a color such as black, and recording is performed.

Conventionally, various acidic substances have been used as color developers, and in particular, phenolic compounds such as bisphenol A and p-hydroxybenzoic acid ester have been used alone or in combination of several types. When these phenols are used, there is a defect that color unevenness occurs or discoloration occurs during storage.

The present inventor has conducted diligent studies in order to eliminate these drawbacks, and as a result, the metal salt compound of salicylic acid ester represented by the following general formula (I) itself has an excellent effect as a developer. Not only that, but the storage stability is significantly improved,
Further, they have found that they also have an excellent effect as a sensitizer for an acidic substance used as a color developer, and arrived at the present invention.

That is, the present invention is usually a colorless or light-colored color-forming substance,
The present invention provides a heat-sensitive recording material containing a compound represented by the following general formula (I).

(In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ₂ represents an alkyl group having 12 to 30 carbon atoms,
Me represents a metal atom, and a represents the valence of the metal. ) In the compound represented by the general formula (I), the alkyl group having 1 to 8 carbon atoms represented by R ₁ is methyl,
Examples thereof include ethyl, propyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl and tert-octyl.

As the alkyl group having 12 to 30 carbon atoms represented by R ₂ ,
Dodecyl, isotridecyl, tetradecyl, hexadecyl, heptadecyl, octadecyl, eicosyl, docosyl, tetracosyl, triacontyl and the like can be used, and a compound having 16 to 22 carbon atoms is particularly preferable.

Examples of the metal atom represented by Me include sodium, potassium, lithium, copper, magnesium, calcium, strontium, barium, zinc, cadmium, aluminum, tin, lead, zirconium, antimony, chromium, molybdenum, iron, cobalt and nickel. Metal can be used,
Particularly, metal salts of Group I, Group II, and Group III are preferable because of their large effects.

Therefore, examples of the compound represented by the above general formula (I) used in the present invention include salicylic acid dodecyl ester zinc salt, salicylic acid dodecyl ester potassium salt, salicylic acid hexadecyl ester zinc salt, salicylic acid stearyl ester calcium salt, salicylic acid stearyl ester. Zinc salt, salicylic acid stearyl ester aluminum salt, salicylic acid stearyl ester copper salt, 5-tert-butyl salicylic acid stearyl ester zinc salt, salicylic acid behenyl ester zinc salt, salicylic acid behenyl ester calcium salt, salicylic acid behenyl ester aluminum salt, salicylic acid behenyl ester copper salt, etc. Can be given.

As described above, these compounds not only exert the excellent effect as a color developer by themselves, but also have an excellent effect of improving storage stability, and also have an effect as a sensitizer. , A developer that has been conventionally used according to its use and required performance; p-octylphenol, pt-butylphenol, p-phenylphenol, bisphenol A, 1,1-bis (p-hydroxyphenylbutane), 2 , 2-bis (4-hydroxy-3,5-dichlorophenyl) propane, p-hydroxybenzoic acid, ethyl p-hydroxybenzoate, butyl p-hydroxybenzoate,
Benzyl p-hydroxybenzoate, 3,5-di-t-butylsalicylic acid, 4,4'-cyclohexylidenediphenol, p-hydroxydiphenoxide, α-naphthol,
β-naphthol, p-hydroxyacetophenone, p-
t-octylcatechol, 2,2'-hydroxybiphenyl, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1 , 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane,
It can also be used in combination with phenols such as 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane or an organic acid.

Examples of the compound represented by the general formula (I) include salicylates, metal alkoxides, metal hydroxides,
It can be easily produced by applying a known method of synthesizing a metal phenolate, such as a method of reacting a metal oxide or a method of synthesizing an alkali metal salt of salicylic acid ester and then reacting this with a metal halide.

Next, a specific synthesis example of the metal chloride used in the present invention will be shown.

Synthesis Example 1 Synthesis of zinc salt of salicylic acid stearyl ester 40 g of methyl cellosolve and 0.82 g of sodium hydroxide were taken and heated and stirred at 80 ° C. to uniformly dissolve them. Then, the mixture was cooled to 40 ° C., and 7.81 g of stearyl salicylate was suspended in 20 g of methyl cellosolve and added. After stirring for 15 minutes, 1.43 g of zinc chloride was added. The mixture was further stirred for 15 minutes at room temperature, and the precipitated powder was filtered off to obtain 6.46 g of white crystals having a melting point of 70 ° C. (Yield 84%) The zinc content of the product was 7.9%, which was in good agreement with 7.8% of the target product.

An infrared spectroscopic analysis, absorption based on the hydroxyl group of a the 3100 and 1400 cm ^-1 in the raw material disappeared, absorbed yield based on carbonyl groups was in 1675 cm ^-1 is moving to 1665 cm ^-1, the desired product Was confirmed.

Synthesis Example 2 Synthesis of calcium stearyl salicylate salt Isopropanol 40 g and stearyl salicylate 3.90 g
It was taken and stirred at 45 ° C. to dissolve it uniformly. Then, while stirring, 0.37 g of calcium hydroxide was poured using 10 g of distilled water.

The mixture was stirred under reflux for 20 minutes and then cooled, and the deposited precipitate was filtered off to obtain 3.85 g of white powder having a melting point of 101 to 103 ° C. (Yield 94
%) The product has a calcium content of 5.1%,
It matched well with%.

An infrared spectroscopic analysis, absorption based on the hydroxyl group of a the 3100 and 1400 cm ^-1 in the raw material disappeared, absorbed yield based on carbonyl groups was in 1675 cm ^-1 is moving to 1665 cm ^-1, the desired product Was confirmed.

Synthesis Example 3 Synthesis of stearyl salicylic acid aluminum salt Aluminum triisopropoxide 0.8 g / g in toluene 25 g
2 g was dissolved and 4.69 g of stearyl salicylate was added thereto. Then, the mixture was stirred under reduced pressure at 50 ° C. while distilling off the solvent. The solvent and by-produced isopropanol were completely distilled off to obtain 4.72 g of a pale red-white powder having a melting point of 67 to 70 ° C. (Yield 9
9%) The aluminum content of the product is 2.3%,
It was exactly the same as 2.3%.

An infrared spectroscopic analysis, absorption based on the hydroxyl group of a the 3100 and 1400 cm ^-1 in the raw material disappeared, absorbed yield based on carbonyl groups was in 1675 cm ^-1 is moving to 1665 cm ^-1, the desired product Was confirmed.

Synthesis Example 4 Synthesis of zinc salt of salicylic acid behenyl ester A white powder product having a melting point of 74 to 76 ° C. was obtained by the same procedure as in Synthesis Example 1 except that the behenyl ester of salicylic acid was used instead of the stearyl ester of salicylic acid.

The zinc content of the product was 6.9%, which was in good agreement with 6.8% of the target product.

An infrared spectroscopic analysis, absorption based on the hydroxyl group of a the 3100 and 1400 cm ^-1 in the raw material disappeared, absorbed yield based on carbonyl groups was in 1675 cm ^-1 is moving to 1665 cm ^-1, the desired product Was confirmed.

Synthesis Example 5 Synthesis of salicylic acid behenyl ester calcium salt A white powder product having a melting point of 103 ° C. was obtained by the same procedure as in Synthesis Example 2 except that salicylic acid behenyl ester was replaced with salicylic acid behenyl ester.

The calcium content of the product is 4.5%,
It matched well with%.

An infrared spectroscopic analysis, absorption based on the hydroxyl group of a the 3100 and 1400 cm ^-1 in the raw material disappeared, absorbed yield based on carbonyl groups was in 1675 cm ^-1 is moving to 1665 cm ^-1, the desired product Was confirmed.

Various dyes are generally known as the colorless or light-colored coloring material used in the present invention, and are not particularly limited as long as they are used for general pressure-sensitive recording paper or heat-sensitive recording paper. .

Specific examples of these dyes include (1) triarylmethane compounds; for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3- (p -Dimethylaminophenyl) -3- (1,2-dimethyl-3-indolyl) phthalide, 3- (p-dimethylaminophenyl)-
3- (2-phenyl-3-indolyl) phthalide, 3,3
-Bis (9-ethyl-3-carbazolyl) -5-dimethylaminophthalide, 3,3-bis (2-phenyl-3-indolyl) -5-dimethylaminophthalide, etc., (2) diphenylmethane compound; , 4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leuco auramine, M-2,4,5-trichlorophenyl leuco auramine, etc. (3) Xanthene compound;
For example, rhodamine-β-anilinolactam, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane,
3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7- (β-ethoxyethylamino) fluorane, 3-piperidino-6
-Methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-
Cyclohexylmethylanilino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7
(4) thiazine compounds such as -γ-chloropropylaminofluorane; for example, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.
(5) Spiro compounds; for example, 3-methylsulpyrodinaphthopyran, 3-ethylspirodinaphthopyran, 3-
Benzylspirodinaphthopyran, 3-methylnaphtho (3
-Methoxybenzo) spiropyran, etc., and these dyes can be used as a mixture of several kinds.

The compound and the colorless colorless dye of the present invention are atomized by a grinding machine such as a ball mill, an attritor, a sand grinder or a suitable emulsifying device, and various kinds of additive materials are added according to the purpose to prepare a coating liquid.

This coating liquid is usually a binder such as polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, starches, styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer, kaolin. , Diatomaceous earth, talc, titanium dioxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, etc. are mixed, but in addition to this, metal soaps, waxes, light stabilizers, water resistance agents, dispersants, defoamers. Etc. can be used. The desired thermosensitive recording medium can be obtained by applying this coating liquid to paper and various films.

The amount of the metal salt compound represented by the general formula (I) of the present invention varies depending on the required performance and recording suitability, and the type and amount of other additives used in combination, and thus is not particularly limited. No, but usually 0.1-10 for 1 part of chromogenic dye
Parts.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example-1 20 g of 3-diethylamino-6-chloro-7-anilinofluorane was ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dye dispersion liquid (A).

20 g of bisphenol A (2,2-bis (4'-hydroxyphenyl) propane) (Comparative Example 1), salicylic acid stearyl ester zinc salt (Example 1) or salicylic acid behenyl ester zinc salt (Example 2) 20 g and stearic acid amide 10 g Was ground in a ball mill together with 100 g of a 10% aqueous solution of polyvinyl alcohol to obtain a developer dispersion (solution B).

20 g of 3-diethylamino-6-chloro-7 (β-ethoxyethyl) aminofluorane was ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dye dispersion liquid (C liquid).

Bisphenol A 10g 10% polyvinyl alcohol aqueous solution
It was ground in a ball mill together with 100 g to obtain a dispersion liquid (D liquid).

Salicylic acid methyl ester zinc salt (Comparative Example 2), salicylic acid stearyl ester zinc salt (Example 3), salicylic acid stearyl ester calcium salt (Example 4), salicylic acid stearyl ester aluminum salt (Example 5), salicylic acid behenyl ester zinc salt ( Example 6)
Alternatively, 20 g of salicylic acid behenyl ester calcium salt (Example 7) was ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dispersion liquid (E liquid).

Solution A and solution B are mixed in a weight ratio of 3:10, or solution C, solution D and solution E are mixed in a weight ratio of 3: 20: 5, and 50 g of calcium carbonate is added to 200 g of the mixed solution and dispersed. To obtain a coating liquid.

The resulting coating liquid was applied onto 50 g / m ² of base paper so that the solid content was 6 g / m ² , and dried to obtain a thermal paper.

Using this thermal paper, a commercial thermal facsimile machine (NEFA
The density of the background after printing and the density of the printed part were measured with X-3000: manufactured by NEC.

In addition, this color developing body is stored at a temperature of 50 ° C., a humidity of 90% and a temperature of 70 ° C. under a dry condition for 48 hours, the background density after printing and the density of a printed portion are measured, and the following formula The residual rate of the density of the printed portion was measured.

The concentration was measured with a Macbeth densitometer RD-514 type.

The results are shown in Table-1.

From the results shown in Table 1, it is understood that the heat-sensitive recording material of the present invention is remarkably excellent in that the color-developing material is less decolored by heat and humidity and the background is less colored.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a normally colorless to light-coloring substance and a compound represented by the following general formula (I). (In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ₂ represents an alkyl group having 12 to 30 carbon atoms,
Me represents a metal atom, and a represents the valence of the metal. )