JPH03266686A - Thermosensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a thermosensitive recording material with satisfactory coloring sensitivity and almost free from texture fog by adding at least, one type of specific diester compound to a thermosensitive coloring layer. CONSTITUTION:A thermal recording material consists of a thermal coloring layer containing a colorless or pale electron-donative dye precursor and an electron-receptive material which allows dyeing through reaction with the dye precursor formed on a support. The thermosensitive coloring layer contains at least one type of a diester compound shown by formula (I). If the compound of formula (I) is used as a sensitizer, the sensitizer becomes a medium and a colorless dye and a color developer form a coloring compound rapidly during heating process, because the sensitizer itself melts speedily due to heat and also thermally melts rapidly and melts at low saturation point with the colorless dye and the color developer. Subsequently, the sensitization effect obtained is significant. Thus the consistency of a developed color during recording process is high, and an obtained thermosensitive recording material demonstrates a high coloring sensitivity.

Description

[Detailed description of the invention] (Field of use in business a) 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 substance ( A two-component coloring system consisting of a color developer (hereinafter abbreviated as a "color developer") is further provided with a heat-sensitive coloring layer in which a binder, a sensitivity improver, a lubricant, a filler, and other auxiliaries are dispersed. Kosho 43-41
No. 60 and Japanese Patent Publication No. 45-14039.

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.

(I) - Secondary color development, no development or theorem required.

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

(3) When paper is used as a support, the quality of the paper is similar to that of ordinary paper, so there is no discomfort.

(4) High color density 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 color-forming heat-sensitive recording materials are the most widely used of all heat-sensitive recording materials, and in recent years,
Its use in fields such as facsimiles, printers, measurement records, and labels has increased significantly.

By the way, for example, in the recent field of facsimile communication,
Along with the increase in speed, the recording speed is also increasing.
There is also a strong demand for improved thermal responsiveness of thermal recording paper so that sufficient color density can be obtained with less thermal energy.

(Problems to be Solved by the Invention) Research has been carried out on various coloring sensitivity improvers to improve thermal responsiveness, but in general, improving thermal responsiveness increases fogging on the skin, which is undesirable. At present, there is no heat-sensitive recording material that can satisfy both the color development sensitivity and the background fog.

That is, conventional color development sensitivity improvers (sensitizers) have the disadvantage that they cause uneven printing when printed using high-speed facsimile machines or energy-saving facsimile machines, and that image reproducibility is not sufficient.

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.

The object of the present invention is to provide a heat-sensitive recording material that has good color development sensitivity and less background fog by using a sensitizer that is highly compatible with colorless dyes, color developers, and the like.

Means for Solving C'BN) The heat-sensitive recording material of the present invention that achieves the above object has a colorless or light-colored electron-donating dye precursor on a support, and a colorless or light-colored electron-donating dye precursor that is reacted with the dye precursor. A thermosensitive recording material provided with a thermosensitive coloring layer containing an electron-accepting substance for color development, characterized in that the thermosensitive coloring layer contains at least one diester compound represented by the following general formula (I). Materials... (I) (However, ^h^2 in formula (I) is an alkylene group having 2 to 4 carbon atoms, ffi, n is an integer of 1 to 3, and X is 0 or S. 1.8 is preferably selected from, for example, an ethylene group, a propylene group, a butylene group, and an isobutylene group.R and ~R6 each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms; , or an alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, a halogen, a nitro group, an aryl group which may have a substituent, or an aralkyl group which may have a substituent, or An aryloxy group which may have a substituent, more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or a halogen , or a nitro group.

Further, R1 and R2 or R4 and R5 may be connected to each other to form an aromatic ring, for example, a naphthalene ring substituted with R5 and R6 is desired.

(■) is preferred. ) (Function) The reason why the compound (I) above exhibits a remarkable sensitizing effect when used as a sensitizer is considered to be as follows. That is, the thermal dissolution rate of the sensitizer itself according to the present invention is not as large as rice grains, and the thermal dissolution diffusion rate and saturation solubility for colorless dyes or color developers are high, so the sensitizer acts as a medium during heating. This is thought to be because the colorless dye and color developer quickly form a color-forming composition.

The present invention will be explained in more detail below.

Representative examples of the compound of formula (I) above are shown below, but the present invention is not intended to be limited thereto ( ( ( ( ( ■ -2) l-3) ■ -4) ■ -5) ! - 6) (i-to) (i-ts) In the thermosensitive coloring layer of the present invention, for example, stearic acid amide,
Stearic acid methylene bisamide, oleic acid amide,
Fatty acid amides such as valmitic acid amide and coconut fatty acid amide can be contained, and various known compounds can also be used in combination.

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. Colorless dyes include triarylmethane compounds, diphenylmethane compounds, and xanthine. These include thiazine-based compounds, thiazine-based compounds, and spirolan-based compounds. Specific examples of colorless dyes are shown below, but the present invention is not limited thereto.

To give some examples of colorless dyes, examples of triarylmethane compounds include 3.3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone), 3.3-bis (p-dimethylaminophenyl)phthalide, 3-(P-dimethylaminophenyl)-3-(I,3-dimethylindole-3-
yl) phthalide, 3-(+)-dimethylaminophenyl)-3-(2-methylindol-3-yl) phthalide, and the like.

As a diphenylmethane compound, 4.4°-bis-
Dimethylaminobenzhydrin benzyl ether, N-
Herophenyl leukoolami:/, N-2,4,S
-)-lichlorophenylleucoauramine and the like are exemplified.

As xanthine compounds, rhodamine-B-anilinolactam, rhodamine (p-nitrino)lactam, 2
-(dibenzylamino)fluorane, 2-phenylamino-6-diedylaminofluorane, 2-(o-chloroanilino)-6-dinithylaminofluorane, 2-(
3,4-Dichloroanilino)-6-dinithylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-phenyl-6-dinithylaminofluorane, 2-anilino-3-methyl -6-Simethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-(isopropyl)amino Fluoran, 2-anilino-3-methyl-6-N-methyl-N-pentylaminofluoran, 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-
Dinitylaminofluorane, 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-dimethylaminofluorane, 2-(p-
methylanilino)-3-methyl-6-ethylaminofluorane, 2-(p-methylanilino)-3-methyl-
6-N~Mejiru 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-methylanilino)-3
-Chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-(p-methylanilino)-3-chloro-6-N-1thyl-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-anilino-3-ethyl-6-N-methyl-N-
Examples include furylmethylaminofluorane. .

Further, examples of the thiazine-based compound include benzoloucomethylene blue, p-nitrobenzylleucomethylene blue, and the like.

As a spiropyran compound, 3-methyl-spiro-
dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3°-cyclolose bilodinaphthopyran, 3-
Examples include benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxybenzo)-spiropyran, and 3-propyl-spiro-dibenzobilane.

In the heat-sensitive recording material of the present invention, the content 1 of the colorless dye in the heat-sensitive coloring layer is from 0.2 to i.

It is preferable to set it as the range of g/m2.

In addition, the color developer that is used together with a colorless dye in the heat-sensitive coloring layer of a heat-sensitive recording material and causes the colorless dye to develop color is
An organic acidic substance that is solid at room temperature and heat-melting is used, -
Examples include phenolic compounds, aromatic carboxylic acid compounds, novolac type phenolic resins, etc.
Typical examples include bisphenol conductors, hydroxybenzoic acid esters, and salicylic acid esters. Further examples include inorganic acids such as activated clay, activated silica, boric acid, and zinc oxide. The content of the color developer in the heat-sensitive coloring layer is preferably in the range of 0.2 to 4.0 g/2.

Among these color developers, phenolic compounds and aromatic carboxylic acid compounds are particularly preferred; some examples include 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis( 4°-hydroxyphenyl)pentane, 2.2-bis(4°-hydroxy-3',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-bis(4°-
hydroxyphenyl)hebutane, 1,1-bis(4゛-
Hydroxyphenyl)-2-methyl-pentane, 1.1
-bis(4°-hydroxyphenyl)-2-ethyl-hexane, lj-bis(4°-hydroxyphenyl)dodecane, 3,3-bis(4°-hydroxyphenyl)pentane, 1,2-bis(4°) -hydroxyphenyl)ethane, 1.1-bis(4゛-hydroxyphenyl)sulfide, i,i-bis(3°-allyl-4-hydroxyphenyl)sulfone, 1.1bis(4°-hydroxyphenyl)sulfone , 4-hydroxy-4′-isopropoxydiphenyl sulfone, 1.1-bis(4°-hydroxyphenyl)ether, 2.2-bis(4″-hydroxy-3°,5°-dichlorophenyl)butane, 2
．． Phenyl 4-dihydroxybenzoate, phenyl 2,4-dihydroxy-4゛-methyl-benzoate, 2,4-dihydroxy-4°-chlorobenzoate? phenyl acid, phenyl 2,4-dihydroxy-6-methylbenzoate, 2,4.6
- Phenyl trihydroxybenzoate, phenyl 2,4-dihydroxy-6,4°-dimethylbenzoate, 264
-Dihydroxy-6-methyl-4°-phenyl chlorobenzoate, benzyl 2.4-dihydroxybenzoate, 2.
Benzyl 4dihydroxy-4°-methylbenzoate, 2.
Benzyl 4-dihydroxy-4°-chlorobenzoate, 2
．． Benzyl 4-dihydroxy-6-methylbenzoate, 2
, 4,6-benzyl trihydroxybenzoate, 2,4-
benzyl dihydroxy-6,4-dimethylbenzoate,
Benzyl 2,4-dihydroxy-6-methyl-4'-chlorobenzoate, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid propyl ester, 4-hydroxybenzoic acid isopropyl ester, 4-hydroxybenzoic acid benzyl ester, 4-Hydroxy-4'-chlorobenzoic acid benzyl ester, 4-hydroxy-4'-methylbenzoic acid benzyl ester, 4-hydroxy-
Examples include compounds such as benzyl 4"-ethylbenzoate, but are not particularly limited to these.

The heat-sensitive coloring layer according to the present invention preferably contains a filler, and examples of such fillers include calcium carbonate, clay, calcined clay silica, zinc oxide, titanium oxide, talc, aluminum hydroxide, and magnesium hydroxide. Examples include inorganic white pigments such as , barium sulfate, and surface-treated silica, as well as organic fine particles such as starch, polystyrene resin, and urea-formalin tMW71.

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

Furthermore, depending on the purpose, waxes such as paraffin wax, carnauba wax, polyethylene wax, and methylol stearamide, and lubricants such as zinc stearate and calcium stearate can be added to improve the water resistance of the paddy. A crosslinking agent or the like that crosslinks the binder can be added to the binder. For applications requiring good recording stability, it is preferable to incorporate a preservation improver such as a phenolic antioxidant.

Conventional methods such as a blade coater and an air knife coater are used to form a heat-sensitive coloring layer on a support using a heat-sensitive paint produced using colorless dyes, color developers, pigments, binders, and other auxiliary agents. , roll coater-rod coater, and other known methods can be used.

In order to improve the storage stability of the heat-sensitive recording material of the present invention, it is preferable to provide an overcoat layer on the heat-sensitive coloring layer. No. 39078, Special Public Interest L
The method described in No.-17478 can be used.

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

First, dispersions A and B in which the following colorless dye is dispersed, dispersions C and D in which a color developer is dispersed, and dispersions E-H in which a sensitizer is dispersed are sandwiched. Adjustment was made using a glider. The modified polyvinyl alcohol used was Gosselan L-32H (trade name) manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.

In addition, the number of blended parts indicates the number of parts by weight.

Tadabanto ■Tate 11 [Liquid A] 3-n-dibutylamino-6-methyl-7-7nilinofluorane 10 parts 10% modified polyvinyl alcohol IO part wood
20 parts [Liquid B] 3-(N-Ethyl-■-yne 1 mil) 7 minnow 6-methyl-7-7 Nilinofluorane 10 parts 10% modified polyvinyl alcohol 10 parts Water 20 parts "Kouyogong" 1 part [C Liquid Co1.1"-bis(p-human Oxyphenyl)propane (
10% denatured polyvinyl alcohol water UD solution] 4-hydroxy-4°-isobroboxydiphenylsulnene 10% denatured polyvinyl alcohol water bottle 1 t milk EE solution] 10 parts 10 parts 20 parts 10 parts 10 parts 20 parts 10% modified polyvinyl alcohol water 10 parts 10 parts 20 parts [Ft&] 10% modified polyvinyl alcohol water [Liquid G] 10 parts 10 parts 20 parts 10 parts 10% modified polyvinyl alcohol 10 parts water

20 parts [H solution] 10 parts 10% modified polyvinyl alcohol 10 parts water

20 parts Next, the above colorless dye dispersions A and B, and C1
D developer dispersion liquid, EH sensitizer dispersion liquid, 30%
10 parts, 15 parts, and 1 part of calcium carbonate dispersion, respectively.
They were mixed at a blending ratio of 5 parts and 10 parts, and 10 parts of a 10% solution of completely saponified polyvinyl alcohol (average degree of polymerization 1000) was added as a main binder to prepare thermal paints having the combinations shown in Table 1 below. However, the sensitizer dispersion liquid was not blended in the comparative example. As calcium carbonate, Callite S^ manufactured by Shiraishi Kogyo was used.

These heat-sensitive paints were coated on 4537 m2 of high-quality paper as a support, and the intermediate layer and the heat-sensitive paint were each coated with a dry weight of 9 to 9.
A heat-sensitive recording material was obtained by applying 10 g/+'' and 4 to 58/■2. The above-mentioned intermediate layer used an inorganic filler layer mainly composed of fired clay, and the ratio of the inorganic filler to the binder was 100:
10 (dry weight ratio), and styrene-butadiene latex was used as the aforementioned binder.

The heat-sensitive recording material on each side shown in Table 1 below, prepared as described above, was processed using a super calender until the Bekk smoothness was 4.
After adjusting the time to be 00 to 600 seconds, the color development sensitivity was measured using a thermal head printing device manufactured by Taishoku Denki.

The color density was measured using a Macbeth densitometer (Macbeth RD-514) with an applied power of 0.4 W/dot, a pulse period of 4.0 ms, and a thermal head resistance of 11.
The test was carried out at 91Ω, and the results shown in Table 1 were obtained as the level of color development sensitivity.

No. table However, in the table ◎...Excellent.

×: Inferior As is clear from the results in this table, the heat-sensitive recording materials of each example having a specific structure of the present invention exhibited superior color development sensitivity compared to the comparative example.

Although the above embodiments have been described with reference to specific examples and numerical values of the present invention, it is of course possible to make various changes and modifications without departing from the broad spirit and scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to obtain a heat-sensitive recording material that has high color density and high color sensitivity during heat-sensitive recording, and the present invention is extremely useful industrially. be.

4 people

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording in which a heat-sensitive coloring layer containing 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. A heat-sensitive recording material characterized in that the heat-sensitive coloring layer contains at least one diester compound represented by the following general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (However, , A_1 and A_2 in the formula (I) have a carbon number of 2 to
m and n are integers of 1 to 3,
2 alkoxy groups, alkenyl groups having 2 to 12 carbon atoms, halogens, nitro groups, aryl groups that may have substituents, or aralkyl groups that may have substituents, or is also a good aryloxy group, R
_1 and R_2 or R_4 and R_5 may be connected to each other to form an aromatic ring. ) 2 In claim 1, A_1 and A_2 are selected from ethylene group, propylene group, butylene group, and isobutylene group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼Thermal recording materials