JPS63242680A - Thermal recording material - Google Patents

Abstract

PURPOSE:To improve not only storage stability but also scratching resistance and head contamination resistance, by containing a usually colorless - light- colored color forming substance and a specific compound. CONSTITUTION:A thermal recording material contains a usually colorless - light-colored color forming substance and a compound represented by general formula (I) (wherein R is a 8-30C alkyl group, n is 1-4, a is 1-4, M is a metal atom., X is -OH or =O1/2 and m is a valency of a metal). For example, the compound represented by the general formula (I) can be easily prepared by adapting a method for synthesizing metal carboxylate reacting alkylmercaptoalkanoic acid with metal alkoxide, metal hydroxide or metal oxide or reacting an alkali metal salt of alkylmercaptoalkanoic acid and metal halide. As the colorless - light-colored color forming substance, various dyes used in general pressure-sensitive or thermal recording paper are used without receiving special limit. Since the quantity of the metal salt compound represented by the general formula (I) changes according to required capacity and recording aptitude, and the kind and quantity of other additive used together, there is no special limit but said compound is used in an amount of 0.1-10pts. on the basis of 1pt. of the color forming dye in general.

Description

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

Thermosensitive recording materials are usually manufactured by coating a colorless or light-colored color-forming substance and a color developer on the surface of a base paper in a separated state together with an aggravating agent, a binder, and other additives. Then, in the recording device, when a heat generating element such as a thermal head or a hot pen comes into contact with this recording medium, the dye and the color developer react to develop a color such as black, and the 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 singly or in combination. When these phenols were used, there were drawbacks such as color unevenness or discoloration during storage.

As a result of extensive studies to eliminate these drawbacks, the present inventor has discovered that the metal salt of alkylmercaptocarboxylic acid represented by the following general formula (I) has excellent effects as a color developer. The inventors of the present invention have discovered that the storage stability is also significantly improved. Further, the following compounds exhibit excellent effects in improving scrubbing properties and head staining.

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

(RS C, Hz-COO)-M (X)---(I
) (wherein, R represents an alkyl group having 8 to 30 carbon atoms, n represents 1 to 4, a represents 1 to 4, M represents a metal atom, and X represents 100 or =0 , and m indicates the valence of the metal.) In the compound represented by the above general formula (I), the alkyl group having 8 to 30 carbon atoms represented by R includes octyl, decyl, dodecyl. , tertiary dodecyl, tetradecyl,
hexadecyl, octadecyl, eicosyl, tocosyl,
Examples include tetradecyl and triacontyl, and compounds having 10 to 22 carbon atoms are particularly preferred.

Metal atoms represented by Me include sodium, potassium, lithium, copper, magnesium, calcium, strontium, barium, zinc, cadmium, aluminum, tin, lead, zirconium, antimony, titanium, chromium, molybdenum, iron, cobalt, Metals such as nickel can be used, and metal salts of groups 1, 2, and 2 are particularly preferred because of their great effects.

Therefore, the compounds represented by the above general formula (I) used in the present invention include the above-mentioned alkylmercapto-acetic acids, β-alkylmercaptopropionic acids, β-alkylmercaptoisobutyric acids, γ-alkylmercaptoacetic acids, etc. Calcium salts, barium salts, zinc salts of alkylmercaptoalkanoic acids having groups 1. Examples include cadmium salts, aluminum salts, stannous salts, zirconium salts, titanium salts, etc., and these may be normal salts or basic salts.

As mentioned above, these compounds not only have excellent effects as color developers themselves, but also have an excellent effect on improving storage stability, so they have been conventionally used depending on the purpose and required performance. Color developer; p-octylphenol, p-t-butylphenol, p-phenylphenol, bisphenol A11.1-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-butylsalicylic acid, 4.4 '-Cyclohexylidene diphenol, p-hydroxydiphenoxide, α-naphthol, β-naphthol, p-hydroxyacetophenone, pt-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, 1,1.3-
) Lis(2-methyl-4-human ot-c-5-cyclohexylphenyl)butane and other nophenols or organic acids can also be used in combination.

The compound represented by the general formula (I) can be prepared, for example, by a method of reacting an alkylmercapto alkaline earth metal alkoxide, a metal hydroxide, or a metal oxide, or by reacting an alkali metal salt of an alkylmercaptoalkanoic acid with a metal halide. It can be easily produced by applying a well-known method for synthesizing metal carboxylates such as.

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

Synthesis Example 1 Silmercapto 1.88 g of sodium hydroxide was dissolved in 250 m7 of water, and 13.27 g of tetradecylmercaptoacetic acid was added. Heat to 70°C to make a homogeneous solution, and add 3.23g of zinc chloride to 22g of water.
- The solution was added dropwise. The mixture was stirred at 80° C. for 20 minutes, and the white precipitate formed was filtered at the same temperature. After washing with water and drying, the melting point is 1.
14.52 g of white powder at 02° C. was obtained.

The zinc content of the product is 10.3%, and the target content is 10.
It was in good agreement with 00%.

Various dyes are well known as color-forming substances that are usually colorless or light-colored and are used in the present invention, and there are no particular restrictions on dyes used in -i pressure-sensitive recording paper or heat-sensitive recording paper. do not have.

Specific examples of these dyes include (I) triarylmethane compounds; for example, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone); Bis(p-dimethylaminophenyl)phthalide, 3-(P-dimethylaminophenyl)-3-(I,2-dimethyl-3-indolyl)phthalide, 3-(p-dimethylaminophenyl)-3-(2- Phenyl-3-indolyl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methyl-3-indolyl)phthalide, 3-(p-dimethylaminophenyl)-3-(I,3-dimethyl -3-indolyl)phthalide, 3,3-bis(9-ethyl-3-carbazolyl)-5-dimethylaminophthalide, 3.3-
(2) diphenylmethane compounds such as bis(2-phenyl-3-indolyl)-5-dimethylaminophthalide;
For example, 4.4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leuco auramine, N-2゜4.5-) I7 chlorophenyl leuco auramine, etc. (3) Xanthine compounds; e.g. , Rhodamine B anilinolactam, Rhodamine (p-nitroanilino)lactam, Rhodamine B (p-nitroanilino)lactam, 2-benzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3 -Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2-〇-chloroanilino-6-dinithylaminofluorane, 2-1chloroanilino-6-diethylaminofluorane Orane, 2-(3゜4-dichloroanilino)-6-diethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-
Tetrahydrofurfurylaminofluorane, 2-anilino-3-methyl-6-N-butyl-N-tetrahydrofurfurylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-isobutylaminofluorane ,
2-octylamino-6-diethylaminofluorane,
2-dihexylamino-6-diethylaminofluorane, 2-totrifluoromethylanilino-6-diethylaminofluorane, 2-butylamino-3-chloro-6-diethylaminofluorane, 2-ethoxyethylamino-
3-chloro-6-diethylaminofluorane, 2-p-
Chloroanilino-3-methyl-6-sibutylaminofluorane, 2-anilino-3-methyl-6-sioctylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-diphenylamino-6 -Dinithylaminofluorane, 2-anilino-3-methyl-
6-cyphenylaminofluorane, 2-phenyl-6-
diethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-isoamylaminofluorane,
2-anilino-3-methyl-5-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-dinithylamino-7-methylfluorane, 2-anilino-
3-methoxy-6-sibutylaminofluorane, 2-o
-chloroanilino-6-sibutylaminofluorane, z
-p-chloroanilino-3-ethoxy-6-N-ethyl-N-isoamylaminofluorane, 2-0-chloroanilino-6-p-butylanilinofluorane, 2-anilino-3-pentadecyl-6-diethylaminofluoran Oran, 2-anilino-3-ethyl-6-sibutylaminofluorane, 2-anilino-3-ethyl-6-N-ethyl-N-isoamylaminofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-3-methoxypropylaminofluorane, 2-anilino-3-chloro-6-N
-ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-anilino-3-methyl-6-N-ethyl-N-tolylaminofluorane, 2-( 3-chloropropylamino)-3
-chloro-6-diethylaminofluorane, etc., (4) thiazine compounds; for example, benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc.
(5) Spiro-based compounds; for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphthopyran (3
-methoxybenzo)spiropyran, 3.3'-dichlorospirodinaphthopyran, etc., and several types of these dyes can also be used in combination.

The compound of the present invention and the color-forming colorless dye are atomized using a grinder such as a ball mill, attrizer, or sand grinder, or a suitable emulsifier, and various additive materials are added depending on the purpose to form a coating liquid.

This coating solution usually contains polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, starches, binders such as styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer, kaolin, Fillers such as diatomaceous earth, talc, titanium dioxide, calcium carbonate, magnesium carbonate, and aluminum hydroxide are blended, but in addition to these, 4-phenoxybiphenyl, 1,2-bis(3-methylphenoxy)ethane,
Sensitizers such as methylene bisbenzoate and benzyl 1-hydroxy-2-naphthyl ester, waxes, light stabilizers, waterproofing agents, dispersants, antifoaming agents, etc. can be used. The desired heat-sensitive recording material can be obtained by applying this coating liquid to the film and various films.

The amount of the metal salt compound represented by the general formula (I) of the present invention is not particularly limited, as it varies depending on the required performance and recording suitability, as well as the type and amount of other additives used in combination. No, but usually 0.1 to 1 part of color-forming dye
Use 10 parts.

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

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

Similarly, 20 g of the sample (see Table 1) and 10 g of 4-phenoxybiphenylene/I were ground together with 100 g of a 10% polyvinyl alcohol aqueous solution in a ball mill to obtain a color developer dispersion (liquid B).

Mix A liquid and B liquid at a ratio of 3=10, and make a mixture of 200
50 g of calcium carbonate was added and dispersed to obtain a coating liquid.

This coating liquid was applied to a base paper of 50 g/rd at a solid content of 6 g/rd.
It was applied and dried to a coating amount of rrr.

Using the obtained thermal paper, a commercially available thermal facsimile machine (
After printing, the density of the background and the density of the printed area were measured using a NEFAX-30007 (Nippon Denki model).

In addition, this coloring body was heated at a temperature of 50°C, a humidity of 90%, and a temperature of 70°C.
It was stored for 48 hours under dry conditions at 0.degree. C., and the density of the background and the density of the printed area after storage were measured, and the residual rate of the density of the printed area after storage was determined from the following equation.

The concentration was measured using a Macbeth densitometer model RD-514.

The results are shown in Table-1.

Example-2 20 g of 3-diethylamino-6-chloro-7-(β-ethoxyethyl)aminofluorane was ground in a ball mill with 100 g of a 10% polyvinyl alcohol aqueous solution to obtain a dye dispersion (liquid A).

Similarly, 2,2-bis(4-hydroxyphenyl)
Propane log and 10 g of 1,2-bis(3-methylphenoxy)ethane were ground together with 100 g of a 10% polyvinyl alcohol aqueous solution in a ball mill to obtain a dispersion (liquid B).

Similarly, 20 g of the sample compound was ground in a ball mill with 100 g of a 10% polyvinyl alcohol aqueous solution,
A dispersion liquid (liquid C) was obtained.

Mix A liquid, B liquid and C liquid at a weight ratio of 3:20:5,
Add 50g of calcium carbonate to 200g of mixed liquid,
A coating liquid was obtained by dispersing it.

This coating liquid was applied to a base paper of 50 g/cd at a solid content of 6 g/cd.
It was applied and dried to a coating amount of rtr.

Using this thermal paper, the same test as in Example-1 was conducted.

The results are shown in Table-2.

From the results in Tables 1 and 2, it can be seen that the heat-sensitive recording material of the present invention has less decoloring due to heat and humidity of the coloring material and less coloring of the background.
It is understood that this is significantly superior.

Claims (1)

[Claims] A color-forming substance that is normally colorless or light-colored, and the following general formula (I
) A heat-sensitive recording material characterized by containing a compound represented by: (R-S-C_nH_2_nCOO)_aM(X)_m
____a(I) (wherein, R represents an alkyl group having 8 to 30 carbon atoms,
n represents 1 to 4, a represents 1 to 4, M represents a metal atom, X represents -OH or =O_1_/_2, and m represents the valence of the metal. )