JPH02248286A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance color forming sensitivity and to reduce background fog by providing a thermal color forming layer containing an electron donating dye precursor, an electron acceptive substance and a specific dibasic acid diester compound being a sensitizer on a support. CONSTITUTION:Paint for forming a thermal color forming layer based on a colorless - light-colored electron donating dye precursor and an electron acceptive substance forming a color upon the reaction with said dye precursor and compounded with a dibasic acid diester compound represented by formula I(wherein A is a 1 to 8C alkylene) group or an alkenylene group, B1 and B2 are a 2 to 4C alkylene group or a substituted alkylene group, R1 and R2 are an aryl group or an aralkyl group, m is an inter of 1 to 3 and n is an integer of 0 to 3) is prepared. This paint is applied to a support such as paper, synthetic paper and a plastic film and dried to form a thermal color forming layer to prepare a thermal recording material.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a heat-sensitive recording material.

(Prior art) Conventional general heat-sensitive recording materials consist of a colorless or light-colored electron-donating dye precursor (hereinafter abbreviated as colorless dye) and an electron-accepting compound (hereinafter abbreviated as colorless dye) on a support such as paper or film. A two-component coloring system consisting of a coloring agent (abbreviated as coloring agent) is further provided with a heat-sensitive coloring layer in which a binder, a sensitivity improver, a lubricant, a filler, and other moving agents are dispersed.For example, Japanese Patent Publication No. 43-4160, It is disclosed in Japanese Patent Publication No. 14039/1983.

This type of two-component color-forming heat-sensitive recording material allows a color image to be easily obtained by heating with a heating element (thermal head, thermal pen, etc.), and has the following characteristics.

(1) - Secondary color development, and development and fixing are unnecessary.

(2) There is no need to replenish the recording machine, and maintenance of the recording machine is easy.

(3) 6 The paper quality is similar to regular paper and does not feel strange.

(4) The degree of zero color development is high and clear images can be obtained.

(5) By changing the type of colorless dye, different color tones can be easily obtained.

Due to these advantages, two-component heat-sensitive recording materials are most commonly used among heat-sensitive recording materials, and their use in fields such as facsimiles, printers, measurement records, and labels has increased significantly in recent years. With the recent increase in speed of facsimile communication, the recording speed is increasing, and thermal responsiveness has been strongly improved so that sufficient color density can be obtained with less thermal energy even on thermal recording paper. It is requested.

Research has been conducted on various coloring sensitivity improvers to improve thermal responsiveness, but improving thermal responsiveness tends to increase background fog. At present, no recording material has been obtained.

(Problem to be solved by the invention) Conventional sensitizers (color development sensitivity improvers) have the drawback of causing uneven printing and insufficient image reproducibility when printed using high-speed facsimile machines or energy-saving facsimile machines. .

Furthermore, if a substance with a low melting point is mixed into the coloring layer, the coloring sensitivity can be improved, but there is a drawback that background fogging occurs.

(Means for Solving the Problems) Therefore, an object of the present invention is to provide a heat-sensitive recording material that has high compatibility with colorless dyes, color developers, etc., has good color development sensitivity, and has little background fog. .

The present invention provides a heat-sensitive recording material in which a heat-sensitive coloring layer is provided on a support, the heat-sensitive coloring layer containing as main components a colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the dye precursor. , in the heat-sensitive coloring layer, the following general formula (where A is an alkylene group or alkenylene group having 1 to 8 carbon atoms, which may have a substituent, B1,
B2 is an alkylene group or substituted alkylene group having 2 to 4 carbon atoms, R,, R, is an aryl group or aralkyl group that may have a substituent, m is 1 to 3, and n is an integer of 0 to 3. This is a heat-sensitive recording material characterized by containing at least one type of dibasic acid diester compound represented by:

A is, for example, malonic acid, succinic acid, methylmalonic acid, ethylmalonic acid, glutaric acid, methylsuccinic acid, adipic acid, pimelic acid, methyladipic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, itaconic acid, citracone. It is preferably a residue of an acid or a Φ dibasic acid such as glutaconic acid.

B1 and B2 are preferably selected from, for example, an ethylene group, a propylene group, a butylene group, an isobutylene group, and those substituted with these groups.

R1 and R2 are preferably, for example, a phenyl group, a naphthyl group, a benzyl group, or a phenethyl group substituted with an aryl group, a halogen group, a nitro group, or an alkyl group or alkenyl group having 1 to 12 carbon atoms.

(Function) The reason why the compound of formula (I) according to the present invention exhibits a remarkable sensitizing effect when used as a sensitizer is considered to be as follows.

That is, not only the sensitizer itself according to the present invention has a high thermal melting rate, but also the colorless dye or color developer has a high thermal melting diffusion rate and saturation solubility in the sensitizer, so that the sensitizer acts as a medium during heating. It is believed that the colorless dye and the color developer quickly form a color-forming composition.

The melting point of the dibasic acid diester compound of formula (I) is from 70 to
150°C is preferred, particularly 80-120°C.

Representative examples of the compound of formula (I) are shown below.

In addition, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, and various other known compounds may be used in combination within a range that does not inhibit the desired effects of the present invention. You can also do it.

The colorless dyes and color developers used in the present invention are not particularly limited as long as they are used in general pressure-sensitive recording materials, heat-sensitive recording materials, etc. Examples of colorless dyes include triarylmethane compounds and diphenylmethane compounds. , xanthine compounds, thiazine compounds, spiropyran compounds, etc. Examples of colorless dyes are shown below, but the invention is not limited thereto.

Some examples of colorless dyes include triarylmethane compounds such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone), 3゜3-bis( p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)
-3-(2-methylindol-3-yl)phthalide, etc. Diphenylmethane compounds include 4. 4'-bis-dimethylaminobenzhydrin benzyl ether, N
-halophenyl-leucoauramine, N-2,4,5-
There are trichlorophenyl leuco auramines, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitrino)lactam,
-(dibenzylamino)fluoran, 2-phenylamino-6-dinithylaminofluoran, 2- (0-chloroanilino)-6-dinithylaminofluoran, 2-
(3,4-dichloroanilino)-6-dinithylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-phenyl-6-dinithylaminofluorane, 2-anilino-3- Methyl-6-dimethylaminofluorane, 2-anilino-3-methyl-6N-methyl-N-
Ethylaminofluorane, 2-anili-3-methyl-
6-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-methyl-6-N-methyl-N-
Pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-dinithylaminofluorane, 2-anilino-3-chloro- 6-dimethylaminofluorane, 2-anilino-3-methyl-6-N-
Ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-isoamylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-anilino-3- Chloro-6-
N-Methyl-N-ethylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-chloro-6-
N-Methyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-
N-ethyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-methyl-6-dimethylaminofluoran Oran, 2-(p-methylanilino)-3-methyl-6-dinithylaminofluorane, 2-(p-methylanilino)-3-methyl-6-
N-methyl-N-ethylaminofluorane, 2-(p-
methylanilino)-3-methyl-6-N-methyl-N-
(isopropyl)aminofluorane, 2-(p-methylanilino)-3-methyl-6-N-methyl-N-pentylaminofluorane, 2-(p-methylanilino)-
3-Methyl-6-N-methyl N-cyclohexylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-ethyl-N-pentylaminofluorane, 2
-(p-methylanilino)-3-chloro-6-dimethylaminofluorane, 2-(p-methylanilino)-3-
Chloro-6-dinithylaminofluorane, 2-(p-methylanilino)-3-chloro-6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-
3-Chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-(p-methylanilino13-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2(p-methylanilino)-3 -chloro-6-N
Methyl-N-pentylaminofluorane, 2(p-methylanilino)-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-
N-methyl-N-furylmethylaminofluorane, 2-
There are anilino-3ethyl-6-N-methyl-N-furylmethylaminofluorane, etc. Thiazine compounds include benzoloucomethylene blue, p-nitrobenzylleucomethylene blue, etc., and spiropyran compounds include 3- methyl spiro-
dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3.3'-cyclolosevirodinaphthopyran, 3-
Examples include benzyl spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benz)-spiropyran, and 3-propyl-spiro-dibenzobilane.

The content of colorless dye in the heat-sensitive recording layer is 0.2 to 1
．． 0 g/m' is preferred.

As a color developer for coloring a colorless dye, an organic acidic substance that is solid at room temperature and heat-fusible can be used, and examples thereof include phenolic compounds, aromatic carboxylic acid compounds, novolac type phenolic resins, and the like. Typical examples thereof include bisphenol derivatives, hydroxybenzoic acid esters, and salicylic acid esters. Furthermore, clay, activated clay, activated silica, and inorganic acids such as boric acid and zinc oxide can also be used. The content of this color developer in the heat-sensitive recording layer is preferably 0.2 to 4.0 g/m2.

Among these color developers, phenolic compounds and aromatic carboxylic acid compounds are particularly preferred, examples of which are listed in 2.2.
-bis(4'-hydroxyphenyl)furopane, 2.2
-bis(4'-hydroxyphenyl)pentane, 2.
2-bis(4'-hydroxy-37,5/-dichlorophenyl)propane, 1,1-bis(4'-hydroxyphenyl)cyclohexane, 2,2-bis(4'-hydroxyphenyl)hexane, 1,1- Bis(4'-hydroxyphenyl)propane, 1.1-bis(4'-hydroxyphenyl)butane, 1.1-bis(4'-hydroxyphenyl)pentane, 1.1-bis(4'-hydroxyphenyl) Hexane, 1, 1-14'-(4'-hydroxyphenyl)hebutane, 1,1-bis(4'-
hydroxyphenyl)2-methyl-pentane, 1,1-
Bis(4'-hydroxyphenyl)-2-ethyl-hexane, 1,1-bis(4'-hydroxyphenyl)dodecane, 3,3-bis(4'-hydroxyphenyl)pentane, 1,2-bis(4') -hydroxyphenyl)ethane, 1,1-bis(4'-hydroxyphenyl) sulfide, 1,1-bis(3'-allyl-4'-hydroxyphenyl)sulfone, 1゜1-bis(4'-hydroxyphenyl) ) sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 1.1-bis(4'-hydroxyphenyl)ethenope2.2-bis(4'-hydroxy-3',5'-dichlorophenyl)butane, 2
, 4-dihydroxybenzoic acid phenyl, 2゜4-dihydroxy-4'-methyl-benzoic acid phenyl, 2+ 4
"Hydroxy-4'-chlorobenzoic acid pheninope"
phenyl 2,4-dihydroxy-6-methylbenzoate,
2.4.6-)! J hydroxybenzoic acid phenyl, 2,
Phenyl 4-dihydroxy-6゜4'-dimethylbenzoate, 2,4-dihydroxy-6-methyl-41-chlorobenzoate, IN phenyl, 2,4-dihydroxybenzoate, 2,4-dihydroxy-4 Benzyl '-methylbenzoate, benzyl 2,4-dihydroxy-4'-chlorobenzoate, benzyl 2,4-dihydroxy-6-methylbenzoate, 2,4.6-)hensyl dihydroxybenzoate, 2,4- Benzyl dihydroxy 6,4'-dimethylbenzoate, 2,4-dihydroxy-6-methyl-
Benzyl 4'-chlorobenzoate, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid brobyl estenope 4-hydroxybenzoic acid isoprobyl estenope 4-hydroxybenzoic acid pendyl estenope 4 hydroxy-4 '-Chlorobenzoic acid benzyl ester, 4-hydroxy-4'-methylbenzoic acid i? ester, 4
Examples include compounds such as -hydroxy-4'-ethylbenzoic acid benzyl ester, but are not particularly limited to these.

Fillers are preferably used in the present invention. Examples of this filler include calcium carbonate, clay, calcined gel, and silicate.
Zinc oxide, titanium oxide, talc, aluminum hydroxide,
In addition to inorganic white pigments such as magnesium hydroxide, barium sulfate, and surface-treated silica, organic fine particles such as starch, polystyrene resin, and urea-formalin resin can be used.

Binding agents for binding colorless dyes, color developers, white organic pigments, etc. on the support include polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, starch and its derivatives, hydroxyl ethyl cellulose, ethyl cellulose, methyl cellulose, carboxymethyl cellulose. Water-soluble polymers such as cellulose derivatives such as styrene maleic anhydride copolymer alkali salts, isobutylene maleic anhydride copolymer alkali salts, polyacrylic acid alkali salts, alginate alkali salts, polyacrylamide, casein, gelatin, etc. styrene/butadiene copolymer,
Various latexes such as polyurethane, polyvinyl acetate, polyacrylic acid, etc. can be used.

Furthermore, depending on the application, waxes such as paraffin wax, carnauba wax, polyethylene wax, and methylol stearamide, and lubricants such as zinc stearate and calcium stearate can be added. , a crosslinking agent for crosslinking the binder, etc. can be blended. For applications requiring good recording stability, it is preferable to incorporate a preservation improver such as a phenolic antioxidant.

Conventional methods such as blade coater, air +
There are known methods such as if coater, roll coater, and rod coater. Medications can be similarly adjusted using conventional methods.

As the support used in the present invention, paper, synthetic paper, plastic film, nonwoven fabric, resin-impregnated paper, etc. can be used. Further, in order to curl the product after coating, it is preferable to coat a water-soluble polymer, latex, etc. on one or both sides of the support. Furthermore, in order to improve coloring sensitivity and prevent dregs from adhering to thermal elements such as thermal heads, it is preferable to provide an intermediate layer mainly containing the above-mentioned inorganic or organic filler between the support and the thermosensitive coloring layer. .

(Example) Hereinafter, the present invention will be explained in more detail with reference to examples.

Next, a formulation example of the dispersion liquid and data on color development sensitivity are shown. In addition, the number of blended parts indicates the number of parts by weight.

[Liquid A]

3-n-dibutylamino-6-methyl-7-anilinofluorane 10 parts 10% modified polyvinyl alcohol 10 parts water
20 parts [Liquid B] 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluorane
10 parts 10% modified polyvinyl alcohol
10 parts water
20 parts [Liquid C] 3-(N-methyl-N-propyl)amino-6-methyl-7-anilinofluorane
10 copies 10%
Modified polyvinyl alcohol 10 parts water
20 copies [D
Liquid] 3-di-n-butylamino-7-(2-chlorophenylamino)fluoran 10 parts 10% modified polyvinyl alcohol 10 parts water
20 parts [Liquid E] 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-anilinofluorane
10 parts 10% modified polyvinyl alcohol
10 parts water
20 parts [Liquid P] l,1'-bis(p-hydroxyphenyl)propane (
Bisphenol A) 106B 10% denatured polyvinyl alcohol water [Liquid Q] 4-Hydroxy-4'-isopropoxydiphenyl sulfone 10% denatured polyvinyl alcohol water [Liquid R] 4.4'-hydroxy-3,3'-allyl-diphenyl sulfone 10% modified polyvinyl alcohol water [liquid X] 10 parts 20 parts 10 parts 10 parts 20 parts 10 parts 10 parts 20 parts 10% modified polyvinyl alcohol water 10 parts 20 parts ~2
A dispersion liquid was prepared by wet dispersion until the particle size was .mu.m. As the modified polyvinyl alcohol, sulfonated Pv^ (trade name: Goselan L-3266) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. was used. Leuco dye dispersions of A, B, CSD, and E, and P, Q,
A color developer dispersion of R, a sensitizer dispersion of A thermosensitive paint was prepared by adding 10 parts of a 10% solution of saponified polyvinyl alcohol (average polymerization ratio 1.000). Calcium carbonate used was Cally SA manufactured by Shiraishi Kogyo.

A 45 g/m2 high-quality paper was used as the support, and the dry weight of the intermediate layer and the heat-sensitive paint was 9 to 10.
g/m" and 4 to 5 g/m2 to obtain a heat-sensitive recording material. For the above-mentioned intermediate layer, an inorganic filler layer mainly composed of fired G was used, and the ratio of the inorganic filler to the binder was 100:1.
0 (dry weight ratio). Styrene-butadiene latex was used as the binder.

A, BSC, DSESP, QSR, and X dispersions were combined to produce Examples 1 to 7 and Comparative Examples 1 to 7 as shown in Table 1.
5 samples were obtained. The dispersion liquid of X was not blended into the samples of Comparative Examples 1 to 5.

These samples were adjusted to have a Bekk smoothness of 400 to 600 seconds using a super calendar, and then their color development sensitivity was measured using a thermal head printing device manufactured by Taishoku Denki.

The color density was measured using a Macbeth densitometer (RD-514 manufactured by Macbeth) with an applied power of 0.4 W/dot,
Pulse period 4.0 ms, thermal head resistance value 119
The test was carried out at 1Ω, and the results shown in Table 2 were obtained. The Examples had better color density than the Comparative Examples.

First Surface Color Density (Effects of the Invention) As described above in detail, according to the present invention, it is possible to obtain a heat-sensitive recording material that has a high color density (and high color development sensitivity) during heat-sensitive recording.

Claims (1)

[Claims] 1. A heat-sensitive coloring layer containing as main components a colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the dye precursor is provided on a support. In heat-sensitive recording materials, the heat-sensitive coloring layer contains the following general formula ▲ mathematical formula, chemical formula, table, etc. may have a substituent, B_1
, B_2 is an alkylene group or substituted alkylene group having 2 to 4 carbon atoms, R_1, R_2 is an aryl group or aralkyl group that may have a substituent, m is an integer of 1 to 3, and n is an integer of 0 to 3. ) A heat-sensitive recording material comprising at least one dibasic acid diester compound represented by: 2, A is malonic acid, succinic acid, methylmalonic acid, ethylmalonic acid, glutaric acid, methylsuccinic acid, adipic acid, pimelic acid, methyladipic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, itaconic acid, The heat-sensitive recording material according to claim 1, which is a residue of a dibasic acid such as citraconic acid or glutaconic acid. 3. The heat-sensitive recording material according to claim 1, wherein B_1 and B_2 are selected from ethylene group, propylene group, butylene group, isobutylene group, and those substituted with these groups. 4. The thermosensitive recording according to claim 1, wherein R_1 and R_2 are phenyl, naphthyl, benzyl, or phenethyl groups substituted with an aryl group, halogen, nitro group, or an alkyl group or alkenyl group having 1 to 12 carbon atoms. material.