JPH05169831A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent fog and to enhance the storage stability of a developed color image, in a thermal recording material containing a leuco dye and a developer as main components, by using a double salt represented by a specific chemical formula and having an m.p. within a specific temp. range as a developer. CONSTITUTION:As a developer of a thermal recording material, a double salt represented by general formula (wherein n is an integer of 1 or 2, each of aromatic rings may have one or more group selected from an alkyl group, a cycloalkyl group, an aralkyl group and an aryl group and A is a nitrogen- containing org. basic compound) is used. This double salt has an m.p. within the range of 70-250 deg.C and, as the nitrogen-containing basic compound, an amine compound, a hydrazine compound or a guanidine compound is used. The double salt is obtained by reacting 2mol of a chlorosalicylic acid derivative such as 3-chlorrosalicylic acid, 1mol of boric anhydride and 1mol of the nitrogen- containing org. basic compound corresponding to one mol of basic nitrogen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more specifically, it contains a double salt of a chlorosalicylic acid derivative as a developer to form a color image with high dynamic color development sensitivity without causing fog, In addition, the present invention relates to a heat-sensitive recording material in which a color image has excellent storage stability.

[0002]

2. Description of the Related Art Recording materials containing a leuco dye and a color developer as main components have been widely put into practical use. Among them, those using a salicylate derivative as a color developer are currently used as pressure sensitive recording materials. Built into advanced recording system. However, a heat-sensitive recording material using a salicylate derivative as a color developer is disclosed in, for example, JP-A-59-165.
Although proposed in Japanese Patent No. 686, JP-A-59-209194 and the like, most of salicylate derivatives proposed hitherto have a high melting point and are suitable for being easily melted by a thermal head. It has not yet been put to practical use due to its lack of a melting point, its high solubility in water, and its large fog in the color image.

On the other hand, a heat-sensitive recording material using a leuco dye and bisphenol A as a color developer has already been widely put into practical use, but it has hitherto been pointed out that the color density decreases when it is stored for a long period of time. Has been done.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in a heat-sensitive recording material using a salicylate derivative as a color developer, and comprises chlorosalicylic acid or its derivative together with a leuco dye. And a double salt as a color developer to form a color image with high dynamic color development sensitivity without causing fogging, and to provide a thermosensitive recording material in which the color image has excellent storage stability. To do.

[0005]

The heat-sensitive recording material according to the present invention is a heat-sensitive recording material containing a leuco dye and a developer as main components.

In the recording material, the developer is represented by the general formula (I)

[Chemical 2]

(In the formula, n represents an integer of 1 or 2, each aromatic ring may have 1 or 2 of an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, and A is a nitrogen-containing organic group. It represents a basic compound) and has a melting point of 70.
A heat-sensitive recording material characterized by being a double salt in the range of ˜250 ° C.

The double salt used as the color developer in the present invention has the general formula (II)

[Chemical 3]

(In the formula, n is the same as above, and the aromatic ring may have 1 or 2 alkyl groups, aralkyl groups or aryl groups.) 2 mol of the chlorosalicylic acid derivative and borohydride It can be obtained by reacting 1 mol of an acid with 1 mol of a nitrogen-containing organic basic compound corresponding to 1 mol of basic nitrogen.

The chlorosalicylic acid derivative is preferably a 3-chlorosalicylic acid derivative, a 5-chlorosalicylic acid derivative or a 3,5-dichlorosalicylic acid derivative. Specific examples of such a chlorosalicylic acid derivative include 3-chlorosalicylic acid derivative. Salicylic acid, 5-chlorosalicylic acid, 3-cumyl-5-chlorosalicylic acid, 3-methyl-5-chlorosalicylic acid, 3-phenyl-5-chlorosalicylic acid, 3-benzyl-5-chlorosalicylic acid, 5-
Chloro-3-isopropyl-6-methylsalicylic acid, 3
-Chloro-5-t-amylsalicylic acid, 3-chloro-5
Examples thereof include benzyl salicylic acid and 3-chloro-5-cyclohexyl salicylic acid.

On the other hand, in the present invention, the nitrogen-containing organic basic compound includes an amine compound and a hydrazine compound. Amine compounds are aliphatic, alicyclic, aromatic, araliphatic,
It may be a heterocyclic primary, secondary or tertiary amine compound. Accordingly, examples of the aliphatic or alicyclic amine compound include propylamine, diethylamine, amylamine, isoamylamine, triethylamine, tripropylamine, diisopropylamine, dibutylamine, hexylamine, N-methyl-n-butylamine,
N, N-dimethylethylamine, diamylamine, glycine ethyl ester, allylamine, ethanolamine,
Examples thereof include diethanolamine, triethanolamine, cyclohexylamine, dicyclohexylamine and the like.

Examples of the aromatic, araliphatic or heterocyclic amine compound include aniline, naphthylamine, methylaniline, anthranilic acid methyl ester, anthranilic acid ethyl ester, diphenylamine, triphenylamine, benzylamine, β-phenethylamine,
Examples thereof include N-ethylbenzylamine, N, N-diethylbenzylamine, 3-amino-1-phenylamine, 1-phenyl-2-p-tolylethylamine, pyridine, piperidine, morpholine, ethyl isonicotinate. ..

Examples of the hydrazine compound include phenylhydrazine, 1-phenylhydrazine, 1-phenylsemicarbazide and the like. Furthermore, in the present invention, a guanidine compound is also useful as the nitrogen-containing organic basic compound. Specific examples of such a guanidine compound include, for example, guanidine, di-o-tolylguanidine, phenylguanidine, N-methylguanidine,
Examples thereof include dimethyl guanidine and tetramethyl guanidine.

The above double salt can be obtained by various methods. For example, a theoretical amount of the chlorosalicylic acid derivative, boric anhydride, and a nitrogen-containing organic basic compound are heated in a nonpolar organic solvent such as a hydrocarbon solvent, dehydrated, and then removed by a method of removing the organic solvent. be able to. The reaction temperature is not particularly limited, but usually 60 to 1
It is about 50 ° C. As the solvent, aromatic hydrocarbon solvents such as benzene, toluene and xylene are particularly preferable, but in some cases, water can also be used as a reaction solvent.

Further, a theoretical amount of the above chlorosalicylic acid derivative is reacted with boric anhydride to obtain one

General formula (III)

[Chemical 4]

(In the formula, n is the same as above, and the aromatic ring may have 1 or 2 alkyl group, cycloalkyl group, aralkyl group or aryl group.) Of the chlorosalicylic acid derivative It can also be obtained by obtaining a borate and reacting the borate of the chlorosalicylic acid derivative with a theoretical amount of a nitrogen-containing basic compound.

The double salt is liquid, waxy or solid at room temperature depending on the kind of the chlorosalicylic acid derivative or the nitrogen-containing organic basic compound used, but both are very stable to heat. Also, it does not decompose easily into acid or alkali. Particularly, in the present invention, the melting point is 70 to 250.
A double salt at ℃, preferably about 80 to 130 ℃ is preferably used as a developer.

The heat-sensitive recording material according to the present invention contains a leuco dye as a color-developing agent and the above-mentioned double salt as a color-developing agent as main components, and can be obtained by a conventionally known ordinary method. it can. That is, a developer and an optional sensitizer and a binder such as water-soluble polyvinyl alcohol and water are mixed and pulverized to prepare an aqueous dispersion of the developer, and separately, similarly, a leuco dye and a binder are prepared. And water are mixed and pulverized to prepare an aqueous dispersion of leuco dye, and then these two dispersions are mixed and applied onto a substrate such as paper,
dry.

The leuco dye is not particularly limited, but examples thereof include 2-chloro-6-diethylaminofluorane, 2-chloro-3-methyl-6-diethylaminofluorane and 3-chloro-6-cyclohexyl. Aminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-
Dibutylaminofluorane, 2-anilino-3-methyl-6-dipentylaminofluorane, 2-anilino-3
-Methyl-6-methylpropylaminofluorane, 2-
Anilino-3-methyl-6-ethyl isopentylaminofluorane, 2-anilino-3-methyl-6-ethylhexylaminofluorane, 2-anilino-3-methyl-
6-methylcyclohexylaminofluorane, 2-anilino-3-methyl-6-ethyl-p-tolylaminofluorane, 2-anilino-3-methyl-6-ethylethoxypropylaminofluorane, 2-anilino-3- Methyl-6-ethyltetrahydrofurfurylaminofluorane, 2-anilino-3-methyl-6-pyrrolidinofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-o-chloroanilino-6-dibutyl Aminofluorane, 2-o-chloroanilino-6-ethylisopentylaminofluorane, 2-o-fluoroanilino-6-diethylaminofluorane, 2-o-fluoroanilino-6-dibutylaminofluorane, 2- m-
Fluoran compounds such as trifluoromethylanilino-6-diethylaminofluorane, 2-chloro-3-methyl-6- {p- (p'-phenylaminophenylamino) phenylamino} fluorane, 3,3-bis (P-Dimethylaminophenyl) -6-dimethylaminophthalide, 3,6,6'-tris (dimethylamino) spiro [fluorene-9,3'-phthalide], 3,3-bis [2- (4- Dimethylaminophenyl) -2- (4-methoxyphenyl)
Vinyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [2- (4-pyrrolidinophenyl) -2- (4-methoxyphenyl) vinyl] -4,5,6,7 Phthalide compounds such as tetrachlorophthalide, 3- (4-diethylamino-2-methoxyphenyl) -3- {1 (4-chlorophenyl) -1,3, -butadienyl} benzophthalide and the like, alone or in combination. It is preferably used.

Examples of the sensitizer include stearamide, dibenzyl oxalate, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, terephthalic acid dibenzyl ester, and 4-known sensitizers. Benzyl benzyloxybenzoate, naphthoyl benzyl ether, m-terphenyl, p-benzyl biphenyl, 1-
Phenyl hydroxy-2-naphthoate, 1,2-diphenoxyethane, 1,2-di (3-methylphenoxy) ethane, 1,2-di (3,4-dimethylphenyl) ethane, bis (p-methoxyphenoxy) Ethyl) ether, benzenesulfonanilide, toluenesulfonanilide and the like are used.

Further, the heat-sensitive recording material according to the present invention may be combined with a developer other than the above-mentioned double salt, if necessary. Examples of such a developer include p-hydroxybenzoic acid benzyl ester, 2,2-bis (p-hydroxyphenyl) propane (bisphenol A), and 3,4'-.
Isopropylidene diphenol, 2,2-bis (p-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxy-3-allylphenyl) propane, bis (4-hydroxyphenyl) acetic acid, 1, 1-bis (4-
(Hydroxyphenyl) butyl acetate, 4,4'-cyclohexylidene diphenol, 4,4'-thiodiphenol, bis-
(4-hydroxy-3-methylphenyl) sulfide, bis (4-hydroxy-3-t-butyl-6-methylphenyl) sulfide, 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone , 3,4-dihydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone, 4,4'-dihydroxy-3 Examples include 3,3′-diallyldiphenyl sulfone, bis [2- (4-hydroxyphenylthio) ethyl] ether, 4,4′-methylenebis (oxyethylenethio) diphenol.

[0023]

As described above, according to the present invention, the double salt of the chlorosalicylic acid derivative used as the color developer has an appropriate melting point that is easily melted by heating with a thermal head and has no sublimation property. In addition, it has low solubility in water and is very stable to heat, acid and alkali. Thus, the heat-sensitive recording material according to the present invention forms a color image with high dynamic color development sensitivity without causing fogging, and the color image is excellent in storage stability such as light resistance, moisture heat resistance, and moisture resistance. It has unprecedented high quality.

[0024]

EXAMPLES The present invention will be described below with reference to Reference Examples and Examples showing production examples of a double salt used as a color developer in the present invention, but the present invention is not limited to these Examples. Absent. Reference Example 1 In a four-necked flask having a stirring bar, a thermometer, a reflux condenser and a water separator connected thereto, 17.6 g (0.1 mol) of 5-chlorosalicylic acid was added to 70 ml of heptane and 10 ml of 3-pentanone. Then, 7.6 g (0.05 mol) of 3-amino-1-phenylbutane was added thereto at room temperature, and the mixture was stirred at room temperature for several minutes, and then boric anhydride 3.09 was added thereto.
g (0.05 mol) was added.

Then, the flask is heated to an internal temperature of 90 ° C.
As described above, the heptane-water azeotrope was distilled out, and only water was collected by the water separator. The heating was continued until the internal temperature finally reached about 110 ° C. and the production of water stopped. After completion of the reaction, the reaction mud was cooled to room temperature to precipitate a white solid in a slurry form. The precipitate was filtered, dried under reduced pressure, washed with 50 ml of water containing 5 ml of methanol, and then again.
After filtering and drying under reduced pressure, 23.4 g of di-5-chlorosalicylic acid-3-amino-1-phenylbutane double salt borate was obtained as a white powder. Table 1 shows melting points and elemental analysis values. Reference Example 2 Toluene 1 was placed in a four-necked flask having a stir bar, a thermometer, a nitrogen inlet tube, a reflux condenser and a water separator connected to it.
00 ml was added and 5-chlorosalicylic acid 17.6 g (0.1 mol), N-methyl-n-butylamine 4.59 g (0.05 mol) and boric anhydride 3.12 g (0.
(05 mol) was added and heated. After the mixture started to reflux, stop supplying nitrogen and continue refluxing for 2 hours,
2.6 ml of water and 50 ml of toluene were recovered.

After this, the reaction mixture is cooled to room temperature,
A white insoluble material was precipitated. The precipitate is filtered off,
It was washed with 20 ml of cold toluene. After drying it under reduced pressure, it is thoroughly washed with 70 ml of water and then dried under reduced pressure.
21.8 g of di-5-chlorosalicylic acid borate-N-methyl-n-butylamine double salt was obtained. Table 1 shows melting points and elemental analysis values of various double salts obtained in the same manner as above.

[0027]

[Table 1]

Examples 1 to 9 2.5 g of double salts 1 to 9 shown in Table 1 and calcium silicate 4.0
g, Papyrrole N680C (Binder from Showa Denko KK, concentration 30% by weight) 2.0 g, zinc stearate 30% by weight dispersion 4.5 g and water 10 g were mixed and pulverized with a paint shaker for 30 minutes to obtain a dispersion. I got A.

Separately, leuco dye 2-anilino-3-methyl-6-ethyl isopentylaminofluorane 0.5 g,
Paint 1.5 g of Papirole N680C and 10 g of water
Dispersion liquid B was obtained by mixing and grinding for 30 minutes with a shaker.
Then, 3.1 g of the dispersion A and 4.0 g of the dispersion A were mixed so that the weight ratio of leuco dye / developing agent was 1/2, and this was coated on paper, dried and then calendered. The surface was smoothed to obtain a heat sensitive recording paper.

For these thermosensitive recording papers, the dynamic color development characteristics are shown in Table 2, the static color development characteristics are shown in Table 3, and the light resistance and heat resistance are shown in Table 4.
Table 5 shows the humidity resistance. Comparative Example A thermal recording paper as a comparative example was obtained in the same manner as in the above Examples 1 to 9 except that bisphenol A was used as the developer. The characteristics of this thermal recording paper are shown in Tables 2 to 5 as in the examples.

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kawai Hajime 1 Tomikamichokocho, Minami-ku, Kyoto 1 1 Yamada Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A thermosensitive recording material containing a leuco dye and a color developer as main components, wherein the color developer is represented by the general formula (I): (In the formula, n represents an integer of 1 or 2, each aromatic ring may have 1 or 2 of an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, and A is a nitrogen-containing organic basic compound. Is a double salt having a melting point in the range of 70 to 250 ° C. 2. A nitrogen-containing organic basic compound is an amine compound,
The heat-sensitive recording material according to claim 1, which is a hydrazine compound or a guanidine compound.