JPS61233586A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material excellent in thermal response and image storage stability, by containing a compound represented by general formula (1) as a developer and further containing at least one compound represented by general formula (2). CONSTITUTION:Compounds represented by general formula (1) (wherein R is an alkyl group, an alkoxy group, an aralkyloxy group and a halogen atom) and general formula (2) (wherein R is a substituted or unsubstituted aralkyl group) are usually added in a respective amount of 5% or more., pref., 10-600%, especially pref., 20-500% by wt. of a dye precursor. If the addition amount of each of them is below 5wt%, thermal response and image storage stability are insufficient and, if more than 600wt%, the adhesion of a heat- meltable substance to a thermal head increases and printing trouble is generated according to circumstances. Further, by adding a heat-meltable substance with m.p. of 80-160 deg.C such as stearamide or N-hydroxymethylstearamide, thermal response is further enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with improved thermal responsiveness and image storage stability.

(l) Conventional heat-sensitive recording materials generally have a heat-sensitive recording layer on a support that is composed mainly of an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting color developer. , by heating with a thermal pen, laser light, etc., the dye precursor reacts with the color developer instantaneously, and a recorded image is obtained. This type of heat-sensitive recording material has the advantages of being able to record with a relatively simple device, being easy to maintain, and not generating noise. It is used in a wide range of fields, including computer terminals, labels, and automatic ticket vending machines for tickets, etc. ◎ The basic performance required of heat-sensitive recording materials is to have sufficient color image density and sensitivity; There is no deterioration of colored images over time.Also, in recent years, the speed of printing articles has been increased, and as the speed of recording devices themselves has increased, recording materials that can cope with this have become available. It is desired to develop a heat-sensitive recording material with excellent heat responsiveness that can provide heat-responsive properties.Furthermore, as heat-sensitive recording materials become more widely used, oils such as hair products, hand creams, and oils and fats contained in skin sweat are being developed. Characteristics such as image preservability (grease resistance) due to adhesion of objects have also come to be required, and a heat-sensitive recording material that satisfies thermal response and image preservability has become desirable. In order to obtain colored images with higher density, methods are known in which various additives are incorporated into the recording layer.

For example, Japanese Patent Publication No. 43-4160 contains urea, phthalic anhydride, acetanilide, etc., Japanese Patent Publication No. 48-19231 contains natural and synthetic waxes such as beeswax, carnauba wax, paraffin wax, and Japanese Patent Publication No. 49-17748. No. 2, discloses a method of adding salicylic acid, phthalic acid monobenzyl ester, etc.

In addition, to improve image storage stability, bis(4-hydroxyphenyl)sulfone is used as a g coloring agent! However, it is described in JP-A-58-119893 that it can be used as However, there are drawbacks such as physical deterioration, and a satisfactory product has not been obtained.

(＠ Purpose of the Invention The purpose of the present invention is to obtain a heat-sensitive recording material with further excellent thermal responsiveness and image storage stability〇(D) Constitution of the Invention Normally colorless or light-colored dye precursor and reaction during heating In a heat-sensitive recording material containing a monochromatic agent that causes the dye precursor to develop color, a compound represented by the general formula (1) is contained as the color developer, and at least one of the compounds represented by the general formula (2) is further contained. By containing this, it was possible to obtain a heat-sensitive recording material with excellent thermal responsiveness and image storage stability.

General formula (1) (In the formula, R represents an alkyl group, an alkoxy group, an aralkyloxy group, or a halogen atom) General formula (2 (In the formula, R represents a substituted or unsubstituted aralkyl group) As a color developer, general By using the compound represented by formula (1), it is possible to obtain a heat-sensitive recording material with good image storage stability, but the thermal responsiveness is not satisfactory, and after examining various additives, the general formula ( By adding the compound shown in 2, the thermal response was improved.

Specific examples of the compound represented by general formula (1) include 4-
Examples include hydroxy-4/-methyldiphenylsulfone, 4-hydroxy-4'-isopropyloxydiphenylsulfone, 4-chloro-4'-hydroxydiphenylsulfone, 4-benzyloxy-47-hy)'roxydiphenylsulfone, etc. It will be done. Specific examples of compounds represented by the general formula (2) include 1-benzyloxynaphthalene,
Examples include 2-benzyloxynaphthalene, 2-P-methylbenzyloxynaphthalene, and 2-1''-chlorobenzyloxynaphthalene.

The compounds represented by the general formula (1) and the general formula (2) according to the present invention are usually added in an amount of 5% by weight or more each based on the dye precursor.

The preferred amount is 10-600 heavy dragons, especially 20-5
00% by weight is preferred. If the amount added is less than 5% by weight, the thermal response and image storage stability will be insufficient, and if more than 600% is added, the adhesion of thermofusible substances to the thermal head, etc. will increase, and printing problems may occur. O Furthermore, by adding a thermofusible substance having a melting point of 80°C to 1'60°C, such as stearamide or N-hydroxymethylstearamide, the thermal responsiveness can be further improved.

The main components used in the heat-sensitive recording material of the present invention will be specifically explained below.

Examples of the dye precursor include triphenylmethane-based, fluoran-based, diphenylmethane-based, thiazine-based, and spiropyran-based compounds. For example, crystal violet lactone, 3-diethylamino-7-methylfluorane, 3-diethylamine-6-chloro-7-methylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamine-7- Anilinofluoran, 3-diethylamine-7-(2-chloroanilino)fluoran, 3-dibutylamino-7-(2-chloroanilino)fluoran, 3-diethylamine-7-
(3-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-(N-
Ethyl-P-)luidino)-6-methyl-27-anilinofluorane, 3-(N-methylcyclohexylamino)-3-methyl-7-anilinofluorane, 3-piperidino-3-methyl-7- Anilinofluorane etc.

Examples of binders include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, water-soluble binders such as styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, and styrene. -Butadiene copolymer, acrylonitrile-butadiene copolymer, methyl acrylate-
Examples include latex-based water-insoluble binders such as butadiene copolymers.

Pigments include diatomaceous earth, Merck, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, etc. In addition, head wear prevention, Higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide, and castor wax are used for the purpose of preventing sticking, and sodium dioctyl sulfoconolate. Dispersants such as benzophenol
and benzotriazole-based ultraviolet absorbers, surfactants, fluorescent dyes, and the like.

Paper is mainly used as the support for the heat-sensitive recording material according to the present invention, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of combinations of these can also be used as desired.

(Powder Example The present invention will be explained in more detail by way of examples.

Example 1 2% of O-4,4-hydroxy-4'-methyldiphenylsulfone 2511 was prepared by dispersing 3-diethylamino-6-methyl-7-anilinofluorane 10I in a ball mill for 24 hours with 30 g of a 2% polyvinyl alcohol aqueous solution. The mixture was dispersed in a ball mill for 24 hours with a 75N aqueous polyvinyl alcohol solution, and further dispersed in a ball mill for 24 hours with a 2% polyvinyl alcohol aqueous solution 75I of 2-benzyloxynaphthalene 25 #e.

After mixing these three types of dispersions, 5% of calcium carbonate was added.
A 0% dispersion liquid 80II was added, a 20% dispersion liquid of stearic acid phosphoric acid 25II, and a 10% polyvinyl alcohol aqueous solution 200# were added and sufficiently stirred to prepare a coating liquid.

Apply the coating liquid to the base paper of "Tsuboryu 5511/In" at a solid coating amount of 4.
The coating was coated and dried so that it became Op/m@, and treated with a super calendar to obtain a heat-sensitive recording material.

Example 2 Example 1 except that 4-hydroxy-4'-isopropyloxydiphenyl sulfone is used instead of 4-hydroxy-4'-methyldiphenyl sulfone in Example 1.
A heat-sensitive recording material was obtained in the same manner as above.

Comparative Example 1 In place of 4-hydroxy-47-methyldiphenylsulfone in Example 1, 2,2-bis(4-human-roxyphenyl)furono was used, and in place of 2-benzyloxynaphthalene, stearamide was used. A heat-sensitive recording material was obtained in the same manner as in Example 1 except for the use.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 2-benzyloxynaphthalene in Example 1 was removed.

The heat-sensitive recording material obtained as described above was recorded using a thermal paper long-distance abrasion tester manufactured by Desktop Electronics, and the color density was measured using a Macbeth densitometer. The drug properties were tested. The results are shown in Table-1.

Table 1 Plasticizer test/The surface of the recorded sample was covered with a food wrap film, allowed to stand at room temperature, and the temperature of the colored area after -1 week was measured using a Macbeth densitometer.

(As is clear from the results shown in Table 1, the heat-sensitive recording material according to the present invention shown in Example 1.2 has better thermal responsiveness and bi-confucian stability than Comparative Example 1.2. It is excellent.

Claims (1)

[Scope of Claims] A heat-sensitive recording material containing a normally colorless or light-colored dye precursor and a color developer that reacts with the dye precursor upon heating to develop color from the dye precursor, wherein the color developer is of the general formula ( 1. A heat-sensitive recording material characterized by containing a compound represented by formula (1) and further containing at least one compound represented by general formula (2). General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents an alkyl group, alkoxy group, aralkyloxy group, or a halogen atom) General formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R represents a substituted or unsubstituted aralkyl group)