JPH02172789A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To enhance coloring sensitivity, the stability of a coloring image by providing a heat sensitive coloring layer containing electron donative achromatic dye and electron acceptive substance and specific triester compound on a support to form a heat sensitive recording material. CONSTITUTION:Electron donative achromatic dye, electron acceptive substance, and triester compound represented by a formula I (where X, Y, Z are phenyl group, naphthyl group which may independently have substituted group, R is hydrogen atom, 1-6C alkyl group) are dispersed in aqueous water-soluble polymer binder solution such as polyvinyl alcohol, etc., to prepare a heat sensitive coloring layer forming coating solution. A sheet or plastic film is coated with the coating solution, and dried to form a heat sensitive coloring layer, thereby obtaining a heat sensitive recording material. The triester compound of the formula I is used as a sensitizer to improve coloring sensitivity and the stability of coloring image.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a recording material using a triester compound, particularly a heat-sensitive recording material with excellent color development and stability (Prior art and its problems) Generally heat-sensitive Recording materials can be recorded in a short time using relatively simple equipment without complicated processes such as development and fixing, do not generate noise (and are relatively inexpensive, etc.), and can be easily used for computer output. It is widely used in printers such as tablets, calculators, recorders for medical needles, automatic ticket vending machines, label fields, copying machines, etc.

The basic principle of these recording methods is that an electron-donating colorless dye and an electron-accepting compound called a color developer chemically come into contact with each other to transform the dye into a colored substance.

The chemical contact is effected by heating with a thermal head, thermal pen, laser beam, or the like.

In recent years, as information-related technology has become more sophisticated, there has been an increasing demand for faster recording speeds and smaller equipment, especially in fields such as facsimile, and the thermal recording materials used in these systems are also required to have even higher sensitivity. It has been demanded.

One method for increasing sensitivity is to lower the melting point of the color developer to a level that maintains storage stability.

However, it is difficult to control and optimize the melting point of a phenolic compound as a color developer through molecular design, and it is not practical due to cost constraints.

Another method is to add a melting point depressant (sensitizer) to the color developer, and many compounds such as amides and waxes have been proposed so far (for example, Publication No. 53-39139, Japanese Unexamined Patent Publication No. 53-26139
No. 1, JP-A No. 535636, JP-A-53-11
Publication No. 036 and Paper and Pulp Technology Times Vol. 28 No. 9 p2
9 (1985) etc.).

Desirable characteristics of these sensitizers are: (1) They should have a melting point in an appropriate range, do not develop color when combined with a color developer/dye, and at the same time should melt at a sufficiently low degree of melting.

(2) Good compatibility with color developer/dye.

(3) The color development of the blended system is sharp.

(4) The color image should be stable and there should be little fading over time.

(5) Industrially easy to manufacture and inexpensive.

etc., but nothing that satisfactorily satisfies all these requirements has yet been known.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned problems and provide a heat-sensitive recording material that has high coloring sensitivity, high coloring density, and high background whiteness.

(Means for Solving the Problems) The present inventors have found that the above problems can be achieved by using a specific triester compound in combination with an electron-donating colorless dye and a color developer. The present invention has been achieved by finding that a heat-sensitive recording material with high sensitivity can be provided, which effectively dissolves them during heating and effectively maintains its fluidity even during the subsequent cooling process.

That is, the present invention is based on the formula: % formula % [wherein X, Y and Z independently represent a phenyl group or a naphthyl group which may have a substituent, and R is a hydrogen atom or a carbon atom having 1 to 6 carbon atoms. represents an alkyl group. ] Provided is a heat-sensitive recording material characterized by containing a triester compound represented by the following.

In the above formula, X, Y and Z represent a phenyl group or a naphthyl group which may have a substituent, and examples of the substituent include a halogen atom, a C11-7 alkyl group, a cycloalkyl group, an acyl group, Examples include an alkoxy group, an aryl group, an aryloxy group, a nitro group, and a cyano group.

Examples of compounds included in the present invention are shown below, but the invention is not limited thereto.

CHsU to H*C1h The triester compound of the present invention can be easily obtained in high yield by esterifying a trimethylolalkane compound with a carboxylic acid, acid I\ride, etc. through an intrashell esterification reaction. , has a melting point of up to about 140°C, and can be used as a heat-sensitive recording material in combination with an electron-donating colorless dye and an electron-accepting compound as a sensitizer.

As the colorless or light-colored electron-donating dye used in the heat-sensitive recording material of the present invention, leuco dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferred;
They can be used alone or in a mixture of two or more.

Specifically, 3,3-bis(p-7methylaminophenyl)-phthalide, 3,3-bis(p-dimethylaminophenyl)-6-enemethylaminophthalide, 3゜3-bis(
p-dimethylaminophenyl)-6-dibutylaminophenyl, 3,3-bis(p-dimethylaminophenyl)
-6-chlorophthalide, 3.3bis(p-dibutylaminophenyl)-phthalide, 3-7chlorohexylamino-6-chlorofluoran, 3-dimethylamine-5,7-
dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane,
3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-1ly-N-ethylamino)-6-
Methyl-7-anilinofluorane, 3-pyrrolidino-6
-Methyl-7-anilinofluorane, 2-(N-(3“
-trifluoromethylphenyl)amino)-6-dinithylaminofluorane, 3-diethylamine-6-methyl-7-(mtrichloromethylanilino)fluorane, 3
Diethylamine-7-(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)
Fluoran, 3-N-methyl-N-amylamino-6-
Methyl-7-anilinofluorane, 3-N-methyl-N
-Cyclohexylamino-6methyl-7-anilinofluorane, 3-diethylamine-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-
Methyl-7(N,N-dibenzylamino)fluorane,
Benzoylleucomethylene blue, 6'-10low 8'
-Methoxy-benzointrinopyrillospiran, 6'-promo 3'-methoxy7-penzoindolinopyrinospiran, 3-(2'-hydroxy-4'dimethylaminophenyl)-3-(2'-methoxy -5"-chlorophenyl)phthalide, 3-(2hydroquine-4-dimethylaminophenyl) to 3(2"-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroquine-4°-diethylaminephenyl) )-3-(2'-methoxy-5'
-methylphenyl)phthalide,: 3-(2"-methoxy-4dimethylaminophenyl)-3-(2"-hydroxy-4'-chloro-5'-methylphenyl)phthalide,
3-morpholino-7-(N-propyl-p-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-
p-4 trifluoromethylanilinofluorane, 3-diethylamino-5-chloro7-(N-benzyl-p-trifluoromethylanilino)fluorane, 3-pyrrolidi/
-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl p-
1-luidino)-7-(α-phenylethylamino)fluoran, 3-diethylamide/-7-(.

methoxycarbonylphenylamino)fluorane, 3-
Diethylamino-5-methyl-7-(α-phenylethylamine)fluorane, 3-7ethylamino-7-piperi/nofluorane, 2-diO-3-(N-methyltoluidino)-7-(p-n butylanilino)fluorane, 3
-(N-bennol-N-cyclohequinylamino)-5,
6-henzo7-α-naphthylamino-4-furomofluorane, 3-diethylami/-5-methyl-7-mentezino-4',5'-henzofluorane, 3,6-cymethoxyfluorane, 3-(p-7 methylaminophenyl)
-3-Phenylphthalide, 3-di(1ethyl-2-methylindole)-3-yl-phthalide, 3-diethylamine-6-phenyl-7azafluorane, 3.3-bis(p-diethylaminophenyl)-6 -dimethylamine phthalide, 3-(p-dimethylamine/phenyl)-3-
(p-dibenzylaminophenyl)phthalide, 3-(N
-ethyl-Nn-amyl)amino-6-methyl-7-
Examples include, but are not limited to, anirite fluorane and the like.

On the other hand, as the electron-accepting compound (color developer) used in the heat-sensitive recording material of the present invention, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, etc. are preferable, and they may be used alone or A mixture of two or more types is used. A specific example is shown below.

4.4′-isopropylidene bisphenol (bisphenol A), 4.4”-isopropylidene bis(0-methylphenol), C4′-5ec-butylidene bisphenol, 414°-isopropylidene bis(2-te
rt-butylphenol), 4,4'-isopropylidenebis(2-chlorophenol), 2゜2'-methylenebis(4-methyl-6-tert-butylphenol)
, 2,2'-methylenebis(4-ethyl-5-tert
-butylphenol), 4,4゛-butylidene bis(6
-tert-butyl-2-methylphenol), 4.4
'-thiobis(6-tert-butyl2-methylphenol), 4.4°-diphenolsulfone, 4.4'-
Diphenol sulfoxide, isopropyl p-hydroxybenzoate, pendinopebrotocatechuate p-hydroxybenzoate, stearyl gallate, 1,7-bis(4-hydroquinophenylthio)-3,5-one oxahefrin, 15 -bis(4-hydroxyphenylthio)
-3oxabencune, 1,3-bis(4-hydroxyphenylthio)-propane, 1,3-bis(4-hydroxyphenylthio)-2-hydroquinoflopane, N,N'
-diphenylthiourea, salicylanilide, 5-chlorosalicylanilide, salicyl 0-chloroanilide, 2-
Examples include, but are not limited to, hydroquine-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, and -hydroxy-2-naphthoic acid.

The dye and developer described above and 1. of the present invention. The IJ ester compound is atomized to a particle size of several microns in a dispersion medium to prepare a coating solution. The ratio of the dye to the color developer used is generally in the range of 1.10 to 10.1 in terms of mJI ratio, and more preferably in the range of 1.5 to 2:1.

The triester compound of the present invention can be used as a sensitizer in an amount of 0.1 to 15 parts by weight per 1 part by weight of the color developer.

As the dispersion medium, an aqueous solution of a water-soluble polymer compound having a concentration of about 10% is generally used.

Specifically, polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methylcellulose, hydroxyethylcellulose, carboxydimethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylic Aqueous solutions of synthetic polymers such as acid amide/acrylic ester/methacrylic acid copolymers, sodium alginate, casein, gelatin, etc. are used, and dispersion is carried out using a ball mill, sand mill, attritor, etc.

The above-mentioned water-soluble polymer compound also functions as a binder that supports and binds the paint components onto the base material after the coating process, but in order to impart water resistance to the paint film, a water-resistant agent is also added to the coating solution. It is also possible to add a polymer latex such as styrene-butadiene latex or acrylic emulsion.

Furthermore, in the heat-sensitive recording material of the present invention, the coating liquid includes:
Various additives are added as necessary.

For example, inorganic pigments such as kaolin, talc, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, and particulate silica are used to prevent stains on recording heads, and fatty acids are used as head runnability improvers. , metal soaps, specifically stearic acid, behenic acid, aluminum stearate, zinc stearate, calcium stearate, zinc oleate, etc. are added.

A coating liquid containing these components is applied to the surface of a substrate such as paper or plastic film using a blade, air knife, roll coater, gravure, etc., and then dried and smoothed. A heat-sensitive recording material of the present invention is obtained.

<Examples> The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Note that all parts and percentages shown in the examples are based on weight.

Synthesis Example 1 [1,1,1-Trimethylolpropane tribenzoate ester (compound No. 1)] 13.42 g (0.10 mol) of trimethylolpropane and 24.92 g (0.31.5 mol) of birin were added. The mixture was dissolved in 300 ml of methylene chloride, and under water cooling, a solution of 43.01 g (0,306 mol) of benzoyl chloride in methylene chloride (50 ml) was added dropwise at a temperature below 40'C (15 minutes). After dropping, raise the temperature and return iJ! for 3 hours. I made it t. After the reaction, the reaction mixture was poured into water and the organic layer was reduced to 1%.
It was washed successively with hydrochloric acid, 1% aqueous sodium hydroxide solution and water. The crude product of 1.1.1 trimethylolpropane tribenzoic acid ester was then dried over sulfuric anhydride and the solvent was distilled off. ．． 29 g (yield 992%) was obtained.

Thin layer chromatography (TLC) and 'H-NMR spectra of this crude product revealed that it was an almost pure frame product. For analysis, a sample roughly recrystallized from a mixed solvent of n-hexane/toluene was used.

Melting point 85-86°C Elemental analysis (wt%) CH Actual value 72.62 6.16 Calculated value
72.63 5.87IR (KBr method) 17
40cm-'(C=O)'! 1-NMR (weight oo form solvent) δ (ppm: TMS standard) 1.07 (3) 1. t, J=7.6Hz) 1.80
(2H, q, J=7.6l-iz)4.52 (61(
,s) 7.35-8.1 (15H,m) Synthesis Example 2 [+,,1. l Trimethylolethane tribenzoic acid ester (compound NO, 2)] 1.1.1- in the same manner as in Synthesis Example 1 except that trimethylolethane was used instead of trimethylolpropane.
1-limethylolethane tribenzoic acid ester was obtained (yield 99.0%).

Melting point 88-89°C Elemental analysis (wt%) CI (Actual d1 value 72.33 5.85 Calculated value 72.21 5.59 IR (KBr method)
1.715cm-'(C-〇)'H-NMR (weight o
o form solvent) δ (ppm: TMS standard) 1.31 (3H,S) 4.50 (6H,s) 7.35-8.1 (15H,m) Example" [ΔLiquid] 3-N- Methyl-N-chlorine 10 parts Hexylamino-6-methylnia-aniso/fluoran 10% Polyvinyl alcohol 20 parts Aqueous solution [Bi night] Bisphere/A 10 parts Calcium carbonate 10 parts 10% Polyvinyl alcohol 10 parts Aqueous solution [Ci night] 1 ．． LL-trimethylol 10 parts Propane tribenzoic acid ester 10% Polyvinyl alcohol 10 parts Aqueous solution A, B and C1ff1 were each prepared separately with an average particle size of 3.
A coating liquid was prepared by mixing 1 part of liquid A, 2 parts of liquid B, and 2 parts of Ct. Coated on commercially available high-quality paper (
Total coating, solid content 6 h/m'') L. After drying, smoothing treatment was performed with Super Nor Sinter to obtain a heat-sensitive recording material.

Calm Side 2 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the following [Di&] was used instead of [Liquid C] in Example 1.

LD liquid 11. ．． 1.1-trimethylol 10 parts Ethane tribenzoic acid ester 10% Polyvinyl alcohol 10 parts Aqueous solution Example 3 Thermal reaction was carried out in the same manner as in Example 1 except that the following [Liquid E 1 was used instead of [B1ff1] in Example 1. Obtained recording materials.

[Ei]p-hydroxybenzoic acid 10 parts Benzyl carbonate 10 parts 10% Polyvinyl alcohol 1.0 parts Aqueous solution Example A The procedure was carried out except that the above [Liquid E] was used instead of [FB solution] of Example 2. A thermosensitive recording material was obtained in the same manner as in Example 2.

A heat-sensitive recording material was prepared in the same manner as in Example 1, except that the following [Liquid F] was used instead of [Liquid C] in Example 1. -1 was obtained.

[Fiffl] Stearic acid amide 1 part 10% Polyvinyl alcohol 10 parts Aqueous solution Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example I, except that the following [Liquid G] was used in place of [Ci&] in Example 1. Obtained.

[Gif&]l)-benzylbiphenyl 10 parts 10% polyvinyl alcohol 10 parts Aqueous solution Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 3, except that water was used instead of [Ci night] in Example 3. .

The heat-sensitive recording materials obtained in the above countries were evaluated for color development sensitivity and color image stability in the following manner. The results are shown in Table 1.

<Evaluation Method> ■Color Development Sensitivity Using a dynamic color development tester manufactured by Taishoku Denki Co., Ltd., color was developed at a printing rate of 0.45 mJ/dat, and the color density was evaluated as Macbeth RD918 type i'j51331. Total (
(Manufactured by Macbeth Co.) and four rivers.

■Colored image stability■ makes it even better! The colored samples were prepared indoors (25°C).
560% RH) for one month, the itf degree and color density were measured, and the retention rate of the density was calculated.

As is clear from the results table of color development sensitivity and color image stability in the first table, the heat-sensitive recording material of the present invention has a
．． Despite the low printing efficiency of 45 mJ/dat, it exhibited very excellent color development sensitivity, and the stability of the color development was also significantly superior to that of the comparative example.

[Effect of the Invention 1] By using the triester compound of the present invention as a sensitizer, excellent color development sensitivity and stability of color images, which are desirable as a heat-sensitive recording material, were exhibited.

Therefore, the present invention can be applied to various fields as a heat-sensitive recording material.

Claims (1)

[Claims] 1. Formula: ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, X, Y and Z independently represent a phenyl group or a naphthyl group which may have a substituent, R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ] A heat-sensitive recording material characterized by containing a triester compound represented by the following.