JPS61272189A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having a white ground, little ground fogging and excellent developed color density, by incorporating a specified biphenyl compound into a thermal color forming layer comprising a colorless or light-colored color forming substance and a color developing substance capable of developing the color of the color forming substance when being heated. CONSTITUTION:The thermal recording material comprises a biphenyl compound of formula (I), wherein R is 1-20C alkyl, allyl, acetyl, propionyl, benzyl, benzoyl, benzenesulfonyl or p-toluenesulfonyl, and each of X and Y is independently hydrogen or nitro, together with a color forming substance and a color developing substance as main constituents, and a binder, a filler and other additives are appropriately incorporated therein. The color forming substance may be a xanthene compound, a triarylmethane compound, a spiropyran compound, a diphenylmethane compound, a thiazine compound or the like, and the color developing substance may be p-octylbiphenyl, p-tert-butylphenol, an aromatic carboxylic acid derivative such as 3,5-di-tert-butylsalicylic acid and 3,5-di-alpha- methylbenzylsalicylic acid or a polyvalent metal salt of the carboxylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that has excellent color development and less background fog.

``Prior Art'' Generally, heat-sensitive recording sheets are produced by dispersing a leuco dye and a color developer such as a phenolic substance into fine particles, then mixing the two, and adding binders, sensitizers, fillers, lubricants, etc. The leuco dye and/or the color developer are melted by heating.

Color recording is obtained through a chemical reaction that occurs upon contact. A thermal printer or the like with a built-in thermal head is used to heat such a heat-sensitive recording sheet to develop color.

Compared to other recording methods, thermal recording (1) produces no noise during recording, and (2) does not require phenomena or fixing.

(3) Maintenance free. (4) Facsimile field due to its relatively inexpensive machines.

It is widely used in the fields of computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, thermal recording labels, etc.

``Problems to be Solved by the Invention'' Examples of heat-sensitive recording materials include heat-sensitive recording paper disclosed in Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. 45-14039, etc.; has low thermal responsiveness and cannot obtain sufficient color density when used for high-speed recording.

et al., it has been shown that thermoresponsiveness can be improved by adding a thermofusible substance. However, even with these techniques, fully satisfactory results have not yet been obtained. In recent years, demands for high-speed recording have become even higher, and there is a strong desire for the development of heat-sensitive recording materials that can adequately support high-speed recording. However, in general, when the sensitivity of a heat-sensitive recording material is increased and its thermal responsiveness is improved, the drawback that background capri occurs is more likely to occur.

"An Unsuccessful Means to Solve the Problem" As a result of extensive research in order to solve the above problems, the present inventor has developed a colorless or light-colored color-forming substance and a color-developing substance that can cause the color-forming substance to develop color when heated. It has been found that the above drawbacks can be overcome by incorporating a biphenyl compound represented by the following formula (1) into the heat-sensitive coloring layer.

(Wherein, R is 01-2o alkyl, allyl, acetyl, fropionyl, benzyl, benzoyl.

In the benzenesulfonyl or p-)luenesulfonyl group, X and Y each independently represent hydrogen or a nitro group. ) The heat-sensitive recording material of the present invention mainly contains the biphenyl compound of formula CI) as well as color-forming substances and color-developing substances as shown below, and may contain other binders, fillers, other additive substances, etc. as appropriate. It is something.

Specific examples of the compound of formula (1) include 4-methoxybiphenyl, 4-ethoxybiphenyl, 4-propyloxybiphenyl, 4-pentyloxybiphenyl, 4-octyloxybiphenyl, 4-tetradecyloxybiphenyl, and 4-hexyloxybiphenyl. Decylonyloxybiphenyl, 4-
Benzyloxybiphenyl% 4-benzoyl oxybiphenyl & 4-henzenesulfonyloxybiphenyl #S 4-p-toluenesulfonyloxybiphenyl,
5-2) O-4-methoxybiphenyl, 4-methoxybiphenyl, 4-allyloxybiphenyl, 4-ethoxy-4'-nitrobiphenyl, 5-nitro-4-acetyloxybiphenyl, Examples include 4-hexadecyl-4'-nitrobiphenyl, and these are used in an amount of 0.2 to 5 times the weight of the color developer. Also, two or more of these may be used in combination.

As the coloring substance, xanthine compounds, triarylmethane compounds, spiropyran compounds, diphenylmethane compounds, thiazine compounds, etc. are used, and specific examples of xanthine compounds include 2-anilino-3
-Methyl-6-diethylaminofluorane, 2-anilino-5-methyl-6-(methylcyclohexylamino)
-Full.

Orane, 2-anilino-5-methyl-6-(ethelisopentylamino)-fluorane% 2-anilino-5-
Methyl-6-diptylaminofluorane, ,2-(
p-chloroanilino)-5-methyl-6-diethylaminofluorane, 2-(p-fluoroanilino)-3-methyl-6-diethylaminofluorane, 2-(p-fluoroanilino)-3-methyl-6 -diptylaminofluorane, 2-anili2-3-methyl-6-(1)-)luidinoetheramino)-fluoran, 2-(1)-)luidino)-5-methyl-6-diethylaminofluorane, 2 -('O-chloroanilino)-6-diethylaminofluorane, 2-(0-chloroanilino)-6-cyptylaminofluorane/, 2-(o-fluoroanilino)-
6-diethylaminofluorane h 2-(0-fluoroanilino)-6-diptylaminofluorane, 2-anilino-3-methyl-6-bisilysine fluoran. 2-
Anilino-3-methyl-6-pyrrolidinofluorane%
2-(m-trifluoromethylanilino)-6-diethylaminofluorane, 2-ethoxyethylamino-3-
Chloro-6-diethylaminofluorane, 2-anili2-3-chloro-6-diethylaminofluorane, 2-anilino-5-methyl-6-siphenylaminofluorane, 2-phenyl-6-diethylaminofluorane, 2-
chloro-5-methyl-6-diethylaminofluorane,
Specific examples of triarylmethane compounds include 2-chloro-6-diethylaminofluorane and 2-methyl-6-diethylaminofluorane, and 3,5'-bis(p-
Dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone)% 5,
3-bis-(p-dimethylaminophenyl)phthalide,
3-(p-dimethylaminophenyl)-s-(1+2-
Examples of spiropyran compounds include dimethylaminoindol-3-yl) phthalides, 5-methyl-
3-spiro-dinaphthopyran, 1,5. Examples of diphenylmethane-based compounds include S-trimethyl-6'-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran), 4,4'- and su-dimethylaminobenzhydrin penzyl ether, Specific examples of the thiazine-based compounds include N-halophenyl-leucoauramine and the like, and benzoylleucomethylene blue and the like. These leuco dyes may be used alone or in combination.

The color developer is p-ofderphenol.

p,-tert-phytylphenol, p-phenylphenol, 1,1-bis(p-hydroxyphenyl)
Furopane, 2,2-bis-(p-hydroxyphenyl)
-Propane, 1.1-(bis-(p-hydroxyphenyl)-7chlorohexyl, 4.4'-sulfonyldiphenol, bis-(3-allyl-4-hydroxyphenyl)
Phenolic compounds such as sulfones, bezodyl p-hydroxybenzoate.

p-Hydroxybenzoic acid ether% 4-hydroxyphthalate dibenzyl, 4-hydroxyphthalate dimethyl, 5
-Ethyl hydroxyisophthalate, 3°5-diter
Examples of aromatic carboxylic acid derivatives such as 7-butylsalicylic acid and 3,5-di-α-methylbenzylsalicylic acid, and polyvalent metal salts thereof.

As a binder, methylcellulose, methoxycellulose, hydroxyethylcellulose, calfoxymethylcellulose, holvinyl alcohol, carboxy-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, styrene, anhydrous Water-soluble ones such as alkali salts of maleic acid copolymers, alkali salts of iso(or diyne)butylene-maleic anhydride copolymers, polyvinyl acetate, vinyl chloride/vinyl acetate copolymers,
Water-insoluble emulsions such as polystyrene, polyacrylic acid ester, polyurethane, and styrene/butadiene/acrylic acid copolymers are used.

As fillers, calcium carbonate, magnesium carbonate,
Examples include magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin, and the like.

Other lubricants such as lead stearate, calcium stearate, aluminum stearate, various surfactants,
Antifoaming agents and the like are added as necessary.

The heat-sensitive recording material of the present invention is prepared by separately pulverizing a color-forming substance, a color-developing substance, and a biphenyl compound represented by formula (1), adding a binder, etc. as necessary, to obtain an average particle size of 0.5.
P~3μ, and before use, mix this to make a coating liquid and apply it to a support and dry it. As the support, any of paper, synthetic paper 1, synthetic resin, film, etc. can be used, but paper is generally used.

"Example" Next, in order to specifically explain the present invention, examples will be described and effects will be shown, but the present invention is not limited to these examples.

Parts indicate parts by weight.

Example 1 A mixture consisting of the following compositions was separately ground using a sand grinder so that the average particle size was 0.5 to 3μ.
Liquids (A) to [C] were prepared by dispersion.

Next, [mu] liquid: [B] liquid: [C] liquid 6 = 47247
A heat-sensitive coloring layer forming solution was prepared by mixing in the proportions of
f/r! ? The mixture was coated and dried on the surface of high-quality paper so that the dry solid content was 10 p/d to obtain a heat-sensitive recording material of the present invention.

Example 2 In place of 2-(0-fluoroanilino)-6-diethylaminofluorane in the composition of solution (A) used in Example 1, 2-(0-fluoroanilino)-6-sibutylamino A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1 except that fluoran was used.

Example 3 Example 4 2-(o-fluoroanilino)-6 was used instead of 2-'(0-fluoroanilino)-6-diethylaminofluorane in the composition of liquid (A) used in Example 1. - diptylaminofluorane is used, and bis-(3
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 2,2-bis-(p-hydroxyphenyl)-propane was used instead of -allyl-4-hydroxyphenyl)-sulfo/.

Example 5 The heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 4-acetylbiphenyl was used in place of 4-methoxyhyphenyl in the composition of liquid (C) used in Example 1. Ta.

Examples 6-19 4-methoxy in the composition of solution (C) used in Example 1 was obtained.

Comparative example 1 4-methoxy in the composition of liquid (C) used in Example 1 Comparative example 2 2-(0-fluoroanilino)-6-diethylamino in the composition of liquid (A) used in Example 1 2-(o-fluoroa, HIJ))-6-diptylaminofluorane was used in place of fluoran, and the ete test results were shown in the following table in place of 4-methoxybiphenyl in the composition of solution (C). show.

(Color Density) The color density was measured using a Macbeth reflection densitometer RD-914 when the recording material was pressed for 5 seconds at 140° C. using a hot plate.

(Heat resistance) When uncolored paper is left in a thermostat at 60'C for 24 hours, the color density is shown.

(Moisture resistance) The color density is shown when uncolored paper is left under saturated water vapor pressure at 60° C. for 24 hours.

"Effects of the Invention" A thermosensitive recording material with a white background, little background capri (self-coloring due to heat and moisture during storage), and excellent color density was obtained.

Claims (1)

[Claims] (1) A biphenyl compound represented by the following formula (I) may be contained in a heat-sensitive coloring layer whose main components are a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated. Features of heat-sensitive recording material. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R is an alkyl, allyl, acetyl, propionyl, benzyl, benzoyl, benzenesulfonyl, or p-toluenesulfonyl group of C_1_ to_2_0, or X, Y
each independently represents hydrogen or a nitro group. )