JPH0745461B2 - Thiobenzoic acid derivative, sensitizer for heat-sensitive recording comprising the derivative, and heat-sensitive recording material containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel thiobenzoic acid derivative, a sensitizer for heat-sensitive recording comprising the derivative, and a heat-sensitive recording material containing the same.

Conventional technology and its problems Thermosensitive recording materials are those in which a so-called thermosensitive coloring layer that develops color by heating is formed on a support such as paper, synthetic paper, resin film, etc. The heating is provided with, for example, a thermal head. A thermal printer or the like is used. Since such a recording material has the advantages that recording can be obtained in a shorter time than other recording materials, that noise is not generated, and that it is inexpensive, it is possible to use a recording recorder for measurement and a computer. It is widely used as a recording material for machines, fax machines, telex, ticket vending machines, etc.

The heat-sensitive color forming layer constituting the heat-sensitive recording material is a layer capable of forming a color image by heating to form an image. In the color-forming layer, a color-forming substance reacts with the color-forming substance at the time of heating to develop a color. And a coloring agent. Conventionally, as a color-forming substance, for example, a lactone, a lactam or a colorless or light-colored leuco dye having a spiropyran ring is used, and as a developer, various phenolic substances have been proposed (Japanese Patent Publication No. 45-14039). No.
4'-isopropylidene diphenol (bisphenol A) is widely used because it is inexpensive and easily available. Such a combination has been used in many heat-sensitive recording materials because of its clear color tone and less fog, but bisphenol A has a slow reaction rate with a leuco dye and is relatively long in color development. Since it has a drawback that it takes time, especially at present when there is a demand for high-speed recording as represented by a high-speed facsimile, it is expected that the reactivity of the developer with the leuco dye is further improved. Appearance is desired. As such a color developer, for example, a phenolcarboxylic acid ester has been developed (Japanese Patent Laid-Open No. 56-14419).
(See publication 3). However, when a phenol carboxylic acid ester is used as a developer, the storage stability of the obtained color image is insufficient, and accordingly, when the heat-sensitive recording material on which the color image is formed is stored for a long period of time. The current situation is that a color developing agent superior to bisphenol A has not yet been developed due to the drawback that the decoloring phenomenon occurs.

Means for Solving the Problems In view of the present situation, the present inventor has recognized that if the reactivity of bisphenol A with respect to a leuco dye can be improved, bisphenol A can be continuously used as a developer. Below, intensive studies have been conducted to enhance the reactivity of bisphenol A with leuco dyes. As a result, when the inventor newly synthesized the thiobenzoic acid derivative represented by the following general formula (1) in the system of bisphenol and leuco dye, the reactivity of bisphenol A with respect to the leuco dye was It has been found that it can be significantly improved and the intended purpose of the invention can be achieved. The present invention has been completed based on such findings.

That is, the present invention has the general formula [Wherein R is a hydrogen atom, a halogen atom, a lower alkyl group,
A hydroxyl group or a lower alkoxy group, M is a polyvalent metal, and n is a valence of M. ] A thiobenzoic acid derivative represented by the following formula, a sensitizer for heat-sensitive recording comprising the thiobenzoic acid derivative represented by the above-mentioned general formula (1), and a basic colorless or light-colored dye on the surface of a support A heat-sensitive recording material provided with a color-forming layer containing a color-developing agent, wherein the color-forming layer contains a thiobenzoic acid derivative represented by the general formula (1). .

The thiobenzoic acid derivative represented by the above general formula (1) is
It is a novel compound which the present inventor first discovered and which has not been described in the literature.

In the general formula (1), examples of the halogen atom represented by R include a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, and the like, and examples of the lower alkyl group include
For example, carbon number 1 such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl group
~ 6 straight-chain or branched-chain alkyl groups, and lower alkoxy groups include, for example, methoxy,
Ethoxy, propoxy, isopropoxy, butoxy, te
Examples thereof include linear or branched alkoxy groups having 1 to 6 carbon atoms such as rt-butoxy, pentyloxy and hexyloxy groups. Examples of the polyvalent metal represented by M include zinc, tin, nickel, cobalt, copper, iron, lead and aluminum.

The thiobenzoic acid derivative represented by the above general formula (1) is
Although it can be manufactured by various methods, the preferred method is as follows.

That is, the thiobenzoic acid derivative of the present invention has the general formula [In formula, R is the same as the above. X represents a halogen atom. ] The benzoic acid halide represented by and hydrogen sulfide and / or its alkali metal salt are reacted, and then the general formula obtained [In formula, R is the same as the above. R'represents a hydrogen atom or an alkali metal atom. ] It is manufactured by reacting a compound represented by the following with a polyvalent metal sulfate, chloride, nitrate, carbonate or acetate.

The reaction of the benzoic acid halide represented by the general formula (2) with hydrogen sulfide and / or its alkali metal salt is usually water, lower alcohols such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, glycerin. And the like, or a mixed solvent thereof. As the benzoic acid halide of the general formula (2) used as a starting material, any conventionally known one can be used. Examples of the other alkali metal salt of hydrogen sulfide, which is a starting material, include sodium hydrosulfide and potassium hydrosulfide. The blending ratio of the benzoic acid halide represented by the general formula (2) and hydrogen sulfide and / or its alkali metal salt is not particularly limited and may be appropriately selected from a wide range, but is usually 1 mol with respect to the former. And the latter 1-5
It is preferable that the amount is about mol, preferably about 1 to 2.5 mol. The reaction can be carried out under cooling, at room temperature or under heating, but is usually about 0 to 100 ° C, preferably 0 ° C to
It is preferably carried out near room temperature. The reaction is generally 1 to
It will end in about 24 hours. Thus, the compound represented by the general formula (3) is produced.

The reaction of the compound of the general formula (3) with a sulfate, chloride, nitrate, carbonate or acetate of a polyvalent metal is usually carried out with water, a lower alcohol such as methanol, ethanol, propanol, isopropanol or butanol, ethylene glycol, Polyhydric alcohols such as propylene glycol and glycerin,
Alternatively, it is carried out in a mixed solvent thereof. As the polyvalent metal sulfate, chloride, nitrate, carbonate or acetate, any of conventionally known ones can be used, for example, zinc sulfate, stannous sulfate, nickel sulfate, cobalt sulfate, cupric sulfate, Iron sulfate, lead sulfate, aluminum sulfate, zinc chloride, stannous chloride, stannic chloride, nickel chloride, cobalt chloride, cupric chloride, ferric chloride, lead chloride, aluminum chloride, zinc nitrate, tin nitrate, Nickel nitrate, cobalt nitrate, copper nitrate, iron nitrate, lead nitrate, aluminum nitrate, zinc carbonate, tin carbonate,
Nickel carbonate, cobalt carbonate, copper carbonate, iron carbonate, lead carbonate, aluminum carbonate, zinc acetate, tin acetate, nickel acetate, cobalt acetate, cupric acetate, ferric acetate, lead acetate,
Aluminum acetate etc. can be mentioned. Compounds of general formula (3) and polyvalent metal sulfates, chlorides, nitrates,
The blending ratio with the carbonate or acetate is not particularly limited and can be appropriately selected from a wide range, but usually the latter is about 0.1 to 2 mol, preferably 1 mol to the former.
It is preferable to set it to about 0.3 to 1 mol. When a compound in which R is a hydrogen atom is used as the compound of the general formula (3), it is preferable to add alkali hydroxide to the reaction system, and the addition amount of the compound of the general formula (3) is The amount is preferably such that it can be dissolved. The reaction may be carried out under cooling, at room temperature, or under heating, but it usually proceeds at about -10 to 100 ° C, preferably at about 0 to 50 ° C. The reaction is generally completed in about 0.5 to 5 hours. Thus, the compound of the present invention represented by the general formula (1) is obtained.

The thiobenzoic acid derivative represented by the general formula (1) of the present invention can improve the reactivity of a basic colorless or light-colored dye with a developer such as bisphenol A, and therefore, the derivative is heat-sensitive recording. It can be preferably used as a sensitizer.

Next, a heat-sensitive recording material using the compound of the present invention as a sensitizer for heat-sensitive recording will be described.

The heat-sensitive recording material of the present invention comprises a support having a color-developing layer containing a basic colorless to light-colored dye and a color developing agent for coloring the dye on heating, wherein the color-developing layer generally contains The thiobenzoic acid derivative of the formula (1) is contained as a sensitizer for heat-sensitive recording.

Basic colorless to light-colored dye (color-forming substance) in the present invention
As the lactone, a conventionally known one can be widely used as long as it is a colorless or light-colored leuco dye having a lactone, lactam or spirolane ring, for example, 2-anilino-3-methyl-6.
-Pyrrolidinylfluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3
-Piperidino-6-methyl-7-anilinofluorane,
2- (p-ethoxyanilino) -3-methyl-6-diethylaminofluorane, 2-xylidino-3-methyl-
6-diethylaminofluorane, 2- (2-chlorophenylamino) -6-diethylaminofluorane, 3-di (n-butyl) amino-7-p-chloroanilinofluorane, 3-diethylamino-7-m- Examples thereof include chloranilinofluoran.

The color developer in the present invention is a solid at room temperature,
As long as it has a property of becoming a liquid or a gas at 50 ° C. or higher and can react with the above-mentioned color forming substance, conventionally known substances can be widely used, and specifically, bisphenol A,
Benzoic acid, salicylic acid, 2,2'-dihydroxydiphenyl, 2,2'-bis (4'-hydroxyphenyl) propane, phloroglysin, 4-tert-butylphenol, 1
-Naphthol, 4-hydroxyacetophenone, 2,2 '
Examples thereof include dihydroxydiphenyl ether, 4-hydroxybenzoic acid methyl ester, and 4-hydroxybenzoic acid benzyl ester. Of these, bisphenol A is particularly suitable.

The ratio of the color-forming substance and the color developer to be contained in the color-forming layer constituting the heat-sensitive recording material of the present invention is not particularly limited, but usually 200 color developer per 100 parts by weight of the color-developing substance. The amount is preferably about 1000 parts by weight, preferably about 400 to 600 parts by weight.

The amount of the thiobenzoic acid derivative of the general formula (1) to be contained in the color forming layer is usually about 10 to 1000 parts by weight, preferably about 30 to 300 parts by weight, based on 100 parts by weight of the color forming substance. Good to do.

The color-forming layer, auxiliary components commonly used in this field,
For example, calcium carbonate, inorganic or organic fillers such as silica, antioxidants such as 2,6-di-tert-butylphenol, ultraviolet absorbers such as benzoin and benzophenone, vinyl chloride resin powder, polyvinyl alcohol, methyl cellulose, etc. The binder and the like can be appropriately mixed. The blending amount of these various components is not particularly limited, but usually about 20 to 300 parts by weight (preferably about 50 to 200 parts by weight) of an inorganic or organic filler per 100 parts by weight of the color forming substance. , 0.01 to 5 parts by weight (preferably about 0.05 to 1 part by weight) of antioxidant, 0.01 to 5 parts by weight of ultraviolet absorber (preferably about 0.05 to 1 part by weight), and 30 parts of binder.
It is preferable that the amount is about 300 parts by weight (preferably about 50 to 100 parts by weight).

In producing the heat-sensitive recording material of the present invention, conventionally known methods can be widely applied. For example, a color-forming substance, a color developer, the compound of the present invention and other auxiliaries are mixed by a conventional method to form a heat-sensitive color forming layer forming liquid. And after applying or impregnating this on a support,
It can be dried. Here, as the support, for example, paper,
Synthetic paper, resin film and the like can be mentioned, but paper is preferable from the viewpoint of price, coating suitability and the like.

The amount of the thermosensitive color-forming layer-forming liquid prepared above coated or impregnated on the support is not particularly limited, but the dry adhesion amount is usually about 4 to 20 g / m ² , preferably 6 to 10 g / m ^2. m ²
It is good to set the degree.

EFFECTS OF THE INVENTION The heat-sensitive recording material of the present invention is extremely excellent in heat-sensitive properties and eliminates the drawbacks of conventional heat-sensitive recording materials. That is, since the thiobenzoic acid derivative of the general formula (1) of the present invention has an action of improving the reactivity between the color forming substance and the color developing agent, the color development by heating is completed in a relatively short time. However, as a result, it can be suitably used in a field in which a high speed recording is required as represented by a high speed facsimile. Moreover, the image formed by color development is
It has excellent storage stability, and therefore there is no fear that the decoloring phenomenon will occur even when the thermosensitive recording material on which a colored image is formed is stored for a long period of time.

Examples The present invention will be further clarified below with reference to Examples and Comparative Examples. In the following, "parts" means "parts by weight" and "%" means "% by weight".

Example 1 67.3 g of flake sodium hydrosulfide (70%) was added to 140 ml of methanol.
After being added and dissolved, 61.8 g of p-methylbenzoic acid chloride was added dropwise at 10 ° C or lower. After reacting at 5-10 ° C for 2 hours, methanol was distilled off under reduced pressure, 160 ml of water and 100 ml of toluene were added.
Was thrown in. Next, add 35% hydrochloric acid at 10 ° C or lower to
After setting to 2, liquid separation was performed, toluene was recovered, and then vacuum distillation was performed to obtain (p-methyl) thiobenzoic acid.

Boiling point: 90-92 ° C / 3mmHg Yield: 51g, Yield: 83.8% 45.7g of (p-methyl) thiobenzoic acid obtained above was added.
Dissolve in 300 ml of 5% sodium hydroxide aqueous solution and add 5%
It was added dropwise to 480 ml of zinc sulfate aqueous solution at room temperature over 60 minutes. The precipitated crystals were collected, washed with water and dried to obtain zinc (p-methyl) thiobenzoate.

Melting point: 112.5 to 113 ° C. Yield: 96.5% Hue: white The structural formula of this compound is as follows.

Incidentally, zinc (p-methyl) thiobenzoate could be obtained by the same treatment as above using zinc chloride, zinc nitrate, zinc carbonate or zinc acetate instead of zinc sulfate.

Example 2 Zinc o-chlorothiobenzoate was obtained in the same manner as in Example 1 except that o-chlorobenzoic acid chloride was used in place of p-methylbenzoic acid chloride.

Melting point: 94 ° C. Hue: white The structural formula of this compound is as follows.

Example 3 Zinc p-hydroxythiobenzoate was obtained in the same manner as in Example 1, except that p-hydroxybenzoic acid chloride was used instead of p-methylbenzoic acid chloride.

Melting point: 110 ° C. Hue: white The structural formula of this compound is as follows.

Example 4 Zinc (p-tert-butyl) thiobenzoate was obtained in the same manner as in Example 1 except that p- (tert-butyl) benzoic acid chloride was used instead of p-methylbenzoic acid chloride.

Melting point: 116.5 ° C. Hue: white The structural formula of this compound is as follows.

Example 5 Zinc (p-methoxy) thiobenzoate was obtained in the same manner as in Example 1 except that p-methoxybenzoic acid chloride was used instead of p-methylbenzoic acid chloride.

Melting point: 136.5 ° C. Hue: white The structural formula of this compound is as follows.

Example 6 Zinc thiobenzoate was obtained in the same manner as in Example 1 except that benzoic acid chloride was used instead of p-methylbenzoic acid chloride.

Melting point: 136.5 ° C. Hue: white The structural formula of this compound is as follows.

Example 7 Nickel thiobenzoate was obtained in the same manner as in Example 1 except that p-methylbenzoic acid chloride was replaced with benzoic acid chloride and the aqueous solution of zinc sulfate was replaced with the aqueous solution of nickel nitrate.

Melting point: 178 ° C Hue: Shrimp brown The structural formula of this compound is as follows.

Incidentally, it was possible to obtain nickel thiobenzoate by performing the same treatment as above using nickel nitrate, nickel chloride, nickel carbonate or nickel acetate instead of nickel nitrate.

Example 8 Using benzoic acid chloride in place of p-methylbenzoic acid chloride and an aqueous cupric chloride solution in place of zinc sulfate aqueous solution,
Cupric thiobenzoate was obtained in the same manner as in Example 1.

Melting point: 138 ° C Hue: orange The structural formula of this compound is as follows.

It should be noted that cupric thiobenzoate could be obtained by the same treatment using copper sulfate, copper nitrate, copper carbonate or copper acetate instead of cupric chloride.

Example 9 (1) Preparation of color-developing substance dispersion liquid 4.0 parts of 3-diethylamino-6-chloro-7-anilinofluorane and 40.0 parts of 10% aqueous polyvinyl alcohol solution were mixed and pulverized with a ball mill to a particle size of 2 to 3 µ. A dispersion of the color forming substance was obtained.

(2) Preparation of developer dispersion Bisphenol A 7.0 parts, 10% polyvinyl alcohol 40.
Mix 0 parts and 10.0 parts of water, and use a ball mill to make a particle size of 2 to 3μ.
To a dispersion liquid of a color developer.

(3) Preparation of sensitizer dispersion for heat-sensitive recording Various thiobenzoic acid derivatives obtained in Examples 1 to 6 above 7.
0 part, 40.0 parts of 10% polyvinyl alcohol and 10.0 parts of water were mixed and pulverized with a ball mill to a particle size of 2 to 3 µ to obtain a dispersion liquid of a sensitizer for heat-sensitive recording.

(4) Preparation of thermosensitive color-forming layer-forming liquid: 3 parts of the color-forming substance dispersion liquid prepared above, 10 parts of the color developer dispersion liquid and 3 parts of the sensitizer dispersion liquid for heat-sensitive recording were mixed to obtain the heat-sensitive material. A color forming layer forming liquid was prepared.

For comparison, water 3 was used instead of the sensitizer dispersion for heat-sensitive recording.
A thermosensitive color forming layer forming liquid was also prepared by using the parts.

(5) Production of thermosensitive recording paper The various thermosensitive coloring layer forming solutions prepared above were applied to one surface of a high-quality paper having a standard basis weight of 52 g / m ² so that the dry adhesion amount was 4 g / m ² . The thermosensitive recording paper was obtained by putting it in a blower dryer to dry it.

(6) Performance evaluation test of thermosensitive recording paper In order to evaluate the thermal sensitivity of the various thermosensitive recording papers obtained above, a thermal head was applied to the thermosensitive color developing layer surface of the thermosensitive recording paper by a facsimile simulator, a voltage of 13V was applied, Application time
The contact was made under two conditions of 1.88 msec and 2.19 msec, and the coloring density at that time was measured by a Beckmann densitometer to examine the dynamic coloring sensitivity.

The results are shown in Table 1 below. From the table, it can be seen that the recording paper of the invention has excellent heat-sensitive properties.

Claims (3)

[Claims] 1. A general formula [Wherein R is a hydrogen atom, a halogen atom, a lower alkyl group,
A hydroxyl group or a lower alkoxy group, M is a polyvalent metal, and n is a valence of M. ] The thiobenzoic acid derivative represented by these. 2. General formula [Wherein R is a hydrogen atom, a halogen atom, a lower alkyl group,
A hydroxyl group or a lower alkoxy group, M is a polyvalent metal, and n is a valence of M. ] A sensitizer for heat-sensitive recording comprising a thiobenzoic acid derivative represented by: 3. A thermosensitive recording material having a color-forming layer containing a basic colorless or light-colored dye and a color developing agent for coloring the dye on heating on a surface of a support, wherein a general formula is contained in the color-forming layer. [Wherein R is a hydrogen atom, a halogen atom, a lower alkyl group,
A hydroxyl group or a lower alkoxy group, M is a polyvalent metal, and n is a valence of M. ] A heat-sensitive recording material containing a thiobenzoic acid derivative represented by: