JPS59176092A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material inexpensive, capable of producing a developed color image which is clear and favorable in preservability, wherein a thermal color forming layer comprising benzoyl peroxide and a naphthol base compound is provided on a base. CONSTITUTION:The thermal color forming layer comprising (A) benzoyl peroxide and (B) a naphthol base compound capable of forming a color by reacting with component (A) when being heated, e.g., alpha-naphthol, beta-naphthol or a derivative thereof, preferably in such a ratio that the quantity of component (A) is 0.05-50pts.wt. per 1pts.wt. of component (B), and further comprising, if required, a filler, a surface active agent, a heat-fusible substance or the like is provided on a base by coating to obtain the objective recording material.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to heat-sensitive recording materials.

[Prior art]

In general, a heat-sensitive recording material is a material in which a heat-sensitive coloring layer that can form a colored image by heating is provided on a support such as paper, synthetic paper, plastic film, or metallized paper. Therefore, it is widely used not only for copying books, documents, etc., but also for recording the output of computers, facsimiles, various autopsy instruments, and writing on identification cards, commuter passes, etc. Many of these heat-sensitive recording materials have been put to practical use, and typical examples include combinations of metal salts of higher fatty acids and gallic acid, combinations of diazo compounds and coupling agents, and lactones. Combinations of lactam or spiropyran ring-containing leuco dyes and organic acids are known.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that is inexpensive, has clear colored images, and has good storage stability, by utilizing a coloring reaction based on a novel combination that is completely different from conventional coloring methods.

〔composition〕

According to the present invention, the heat-sensitive recording material is characterized in that a heat-sensitive coloring layer containing as main components benzoyl peroxide and a naphthol compound that develops color by reacting with benzoyl peroxide when heated is provided on the support. is provided.

The heat-sensitive recording material of the present invention utilizes a color-forming reaction between benzoyl peroxide and a naphthol compound. The mechanism of this color reaction is not clear.

This is thought to be because the reaction between the two produced a product with a new resonance structure that exhibits light absorption.

The naphthol-based compound used in the present invention is one that develops color by reacting with benzoyl peroxide when heated, and includes α-naphthol, α-naphthol,
β-naphthol and derivatives thereof. Examples of naphthol derivatives include various amides of hydroxynaphthoic acid such as 3-hydroxy-2-naphthoic acid;
Examples include naphthol AS, N-ethyl-3-hydroxy-2-naphthamide, N-propyl-3-hydroxy-2-naphthamide, and the like. In the present invention, the naphthol-based compound and benzoyl peroxide may be used in an appropriate ratio so that the two react with each other under heat to form a color.
Benzoyl peroxide is used in an amount of 0.05 to 50 parts by weight per 1 part by weight of the naphthol compound.

The support used in the present invention includes those commonly used in conventional heat-sensitive recording materials, such as paper, synthetic paper, plastic film, metal-deposited paper, and cloth.

In the present invention, in order to bind and support the benzoyl peroxide and naphthol compounds on the support, various binders commonly used in heat-sensitive recording materials using leuco dyes can be used as appropriate, such as polyvinyl alcohol. , starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer,
Water-soluble acrylic acid amide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to polyvinyl acetate, polyvinyl acetate,
Polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. Latex can be used.

In addition, in the present invention, in addition to the benzoyl peroxide and naphthol compounds, if necessary, auxiliary additive components commonly used in heat-sensitive recording materials using leuco dyes, such as fillers, surfactants, thermofusible A sexual substance (or lubricant), etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium carbonate and silica. In addition, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned, and examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts. In addition, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible materials. Examples include organic compounds having a melting point of about 50 to 200°C.

The heat-sensitive recording material of the present invention is produced by applying a heat-sensitive coloring layer coating solution containing the above-mentioned components onto a support and drying it.

〔effect〕

According to the present invention, by utilizing the color reaction between benzoyl peroxide and a naphthol compound, it is possible to obtain a heat-sensitive recording material that is inexpensive and has high image clarity and storage stability.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Note that all parts and percentages below are based on weight.

Example 1 A mixture having the following composition was ground and dispersed in a ball mill for 24 hours to prepare liquid A and liquid B.
Solution and Solution B were further mixed at a ratio of 1:1 to prepare a heat-sensitive coloring layer coating solution.

[Liquid A]

Benzoyl peroxide 4 parts Hydroxyethyl cellulose 10 parts (10% aqueous solution) Water
36 parts [Liquid B] α-naphthol 5 parts Methylcellulose (15% aqueous solution) 20 parts Calcium carbonate
1 part water
24 parts Next, the coating liquid for the thermosensitive coloring layer was applied onto one side of a high-quality paper (tsubo JJ: 50 g/m) and dried to obtain a thermosensitive recording material having a thermosensitive coloring layer with a coating weight of 7 g/m.

Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that α-naphthol in Solution B was replaced with β-naphthol.

Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the following liquid 0 was used in place of liquid B in Example 1.

[Liquid C]

3-hydroxy-2-naphthanilide 7 parts (naphthol-AS) Urea-formalin resin 1 part N-octadecylcarbamoylbenzene 1 part polyvinyl alcohol (10% aqueous solution) 25 parts water
16 parts Comparative Example 1 A thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that crystal violet lactone (leuco dye) was used instead of benzoyl peroxide in Solution A of Example 1.

The heat-sensitive recording materials of the present invention and comparative heat-sensitive recording materials obtained above were used as samples to conduct tests for color development and organic solvent resistance.

The results are shown in Table-1. The color development test was performed using a thermal gradient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for each sample.
Printing was performed under the conditions of 0° C., 2 kg/cJ, and 1 second, and the image density and background density at that time were measured using a Macbeth RD-51/I densitometer. The organic solvent resistance was determined by dropping ethanol on the image area and non-image area and measuring the image and background density after air drying.

As can be seen from the results in Table 1, the heat-sensitive recording material of the present invention provides clear images with excellent solvent resistance.

Procedures Amendment Written June 9, 1982 1, Indication of the case Patent Application No. 49962 of 1988 2, Title of the invention Thermal recording material 3, Person making the amendment Relationship to the case Patent applicant address Tokyo 1-3-6 Nakamagome, Ota-ku Name
(674) Rico Co., Ltd. - Representative Hama 1)
Hiro 4, Agent 151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo
Date of amendment order: 6. Number of inventions increased by amendment: 0.8. Contents of amendment: The following amendments will be made to the specification of the application.

(1) After “naphthamide” on page 3, line 8, “,N-
γ-morpholinopropyl-3-hydroxy-2-naphthamide.

(2) “Methyl cellulose (15
% aqueous solution)” should be corrected to “methylcellulose (5% aqueous solution).”

(3) In the first line of page 8, "For comparison purposes" will be corrected to "For comparison purposes."

Claims (1)

[Claims] (1) A heat-sensitive recording material characterized in that a heat-sensitive color-forming layer containing as main components benzoyl peroxide and a naphthol compound that develops color by reacting with benzoyl peroxide when heated is provided on a support.