JPS62259888A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent the fading of a recording part due to the contact with water or alcohol or the color development of a white paper part due to the contact with vinegar, by respectively using specific substances as the leuco dye and coupler of a thermal recording material. CONSTITUTION:The title thermal recording material is formed by providing a thermal color forming layer based on a leuco dye, a coupler and a binder on a support and further providing an overcoat layer comprising an aqueous emulsion of a water-soluble resin or a water-insoluble resin on said thermal color forming layer. As the leuco dye, 3-(N-cyclohexyl-N-methylamine)-6- methyl-7-anilinofluorane is contained and, as the coupler 4, 4'- dihydroxydiphenylsulfone is used and 1,1,3-tris(3-t-butyl-4-hydroxy-6-methylphenyl) butane is contained in said thermal color forming layer. The coupler is generally used in an amount of 1-10pts.wt. per 1pts.wt. of the leuco dye.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

[Prior art]

A thermosensitive recording material is a recording material with a structure in which a so-called thermosensitive coloring layer that develops color when heated is formed on a support such as paper, synthetic paper, or resin film, and a thermal head is built in to heat the material to develop the color. A thermal printer or the like is used. Compared to other recording materials, such heat-sensitive recording materials are capable of producing records in a short time using relatively simple equipment without the need for complicated processes such as development and fixing, and are less likely to generate noise or pollute the environment. It has the advantages of being free of paper and low cost, and is used for copying papers, books, documents, etc., and is also used as output recording paper for facsimile machines, measuring instruments, etc.

However, such heat-sensitive recording materials are colored images obtained by a thermal reaction between leuco dye and an acidic substance such as a phenolic substance or an organic acid as a color developer. There was a major problem in that the colored areas would be discolored when agents such as dioctyl phthalate, diptyl phthalate, dihexyl phthalate, and dioctyl adibate penetrated. This problem is solved by providing an overcoat layer of water-soluble resin or water-insoluble resin in an aqueous emulsion on the heat-sensitive coloring layer.
It has also come to be used in POS labels for price tags used in supermarkets, which previously could not be used with heat-sensitive recording materials.

However, as its usage has expanded, it has become clear that it has disadvantages such as discoloration of the recording area due to contact with water, alcohol, etc., and discoloration of the white paper area when contact with vinegar.

〔the purpose〕

The object of the present invention is to provide a heat-sensitive recording material that improves the above-mentioned conventional drawbacks, that is, a heat-sensitive recording material that eliminates fading of the recorded area due to contact with water, alcohol, etc., and color development of the blank area due to contact with vinegar. It is about providing.

[Structure] According to the present invention, a thermosensitive coloring layer containing a leuco dye, a color developer, and a binder as main components is provided on a support, and a water-soluble resin or a water-insoluble resin is coated on the thermosensitive coloring layer. In a heat-sensitive recording material provided with an overcoat layer using an aqueous emulsion, the leuco dye is 3-(N-cyclohexyl-N
Methylamino)-6-methyl-7-anilinofluorane and 4,4'-dihydroxydiphenylsulfone were used as the color developer, and 1,1,3-tris[3-1] was used in the thermosensitive coloring layer. Provided is a heat-sensitive recording material containing -butyl-4-hydroxy-6-methylphenylcobutane.

In the present invention, the ratio of the leuco dye and the color developer used is 1 part of the leuco dye! For @, the color developer is generally 1 to 1
It is used in an amount of 0 parts by weight, preferably 2 to 6 parts by weight. Also Li, 3)! The ratio of Js(3-t-butyl-4-hydroxy-6-methylphenyl)butane used is generally 0.1 to 5 parts by weight per 1 part by weight of the leuco dye.
It is preferably used in an amount of 0.5 to 2 parts by weight.

In the present invention, in order to bind and support the leuco dye and the color developer on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol,
Starch and its derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose,
Cellulose conductors such as methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone,
Acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, imbutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin,
In addition to water-soluble polymers such as casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, etc. Latexes such as polymers and styrene/butadiene/acrylic copolymers can be used. In addition,
For the protective layer in the present invention, a water-soluble polymer as described above is used.

In addition, in the present invention, in addition to the leuco dye and the color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances, etc. (or lubricant) etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aqueous dispersion of aluminum, zinc hydroxide, barium sulfate, clay, Merck, and surface-treated inorganic fine powders such as calcium and silica. In addition, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin may be mentioned. 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, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-diboxy-hexahydrophthalates, higher ketones, and other thermofusible products. Examples include organic compounds having a melting point of about 50 to 200°C.

[Metal practice]

Next, the present invention will be explained in more detail using examples. In addition, all of the parts and parts shown below are based on the weight.

Example 1 [Liquid A] 3-(N-cyclohexyl-N-methylamino)-6-methy''-7-a-linof'ora''' 10 parts 10
%Hydroxyethyl cellulose aqueous solution W, 5B
3 water 1
5 parts [Liquid B] 4.4'-dihydroxydiphenylsulfone 20
Part 1.1.3-Tris(3-t-butyl-4-hydroxy-6-methy)"=') Buta y 8 parts 10% polyvinyl alcohol aqueous solution 15 parts Water 40 parts [Liquid C] Zinc stearate 10 Part calcium carbonate 40 parts 5% methylcellulose aqueous solution 50 parts Water
50 parts [Liquid D] Silica (Mizusawa Kagaku fi Mizukasil P-527) 5 parts 1
150 parts of 0% PVA aqueous solution Of the mixture consisting of the above composition, solutions A to C were each mixed with an average particle size of 2 μm.
Liquids A, B, and C were prepared by dispersing with a sand mill as follows. On the other hand, for the liquid, mix and stir the above composition.D
A liquid was prepared.

Next, 6 parts of liquid A, 20 parts of liquid B, 30 parts of liquid C, 1
70 parts of 0% polyvinyl aqueous solution and 20-thi fatty acid amide emulsion (Hydrin D manufactured by Middle East Yushi Co., Ltd., ■-7)
A heat-sensitive coating liquid was prepared by mixing and stirring 35 parts of
The mixture was coated on a commercially available high-quality paper using a wire bar so that the dry coating amount was 60% and dried to obtain a heat-sensitive coloring layer. On the thus obtained heat-sensitive layer, Liquid D was applied and dried to a thickness of 2η (solid content equivalent) to obtain a heat-sensitive recording material of the present invention.

Comparative Example 1 3-diethylamino-6-methyl-7-anilinoflurane was substituted for 3-(N-cyclohexyl-N-methylamine)-6-methyl-7-anilinofluorane in solution A of Example 1. Using oran, 1,1,3-tris (
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 3-1-butyl-4-hydroxy-6-methylphenyl)butane was omitted.

Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 1.1.3-tris(3-t-butyl-4-hydroxy-6-methylphenyl)butane of liquid B was removed from Example 1. I got it.

The heat-sensitive recording material obtained as described above was used as a sample and printed using a label printing machine (Hyakuni Co., Ltd., manufactured by Kari ■). In order to test the reliability of the image area, the following tests were conducted on each sample after printing.

(1) Water resistance test The printed sample was immersed in water at 20°C for 24 hours, and the density of the printed area and blank area after immersion was measured.

(2) Alcohol resistance test The printed sample was immersed in commercially available Japanese sake (special grade) for 24 hours, and the density of the printed area and blank area at the immersion edge was measured.

(3) Corrosion Vinegar Resistance Test The printed sample was immersed in commercially available vinegar (grain vinegar) for 24 hours, and the density of the printed area and blank area after immersion was measured.

(4) Plasticizer resistance test U Sample after printing and commercially available soft vinyl chloride (Dialap MS
-A) and load 300vc on it! After applying Il, the sample was left for 72 hours at 20° C. and 65 SRH, and the density of the printed area and blank area was measured. In each case, a Macbeth densitometer RD-514 (Ratten A 106) was used to measure the concentration.

The above results are shown in Table-1.

(Margin below) Table-1 Values in parentheses are percentages of before processing.

〔effect〕

As is clear from the examples, the heat-sensitive recording material of the present invention has
There is no discoloration of the recorded area due to contact with water, alcohol, etc., and no color development of the blank area due to contact with vinegar, which greatly contributes to improving the quality of heat-sensitive recording materials.

Claims (2)

[Claims] (1) A thermosensitive coloring layer containing a leuco dye, a color developer, and a binder as main components is provided on a support, and an overcoat layer is formed on the thermosensitive coloring layer with an aqueous emulsion of a water-soluble resin or a water-insoluble resin. A heat-sensitive recording material comprising 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane as the leuco dye and 4,4'-dihydroxydiphenylsulfone as the color developer. A heat-sensitive recording material characterized by: (2) The heat-sensitive recording material according to claim 1, wherein the heat-sensitive coloring layer contains 1,1,3-tris(3-t-butyl-4-hydroxy-6-methylphenyl)butane.