JPH064354B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a developer.

(B) Conventional Technology A thermosensitive recording material is a recording material having a structure in which a so-called thermosensitive coloring layer that develops color by heating is formed on a support such as paper, synthetic paper, or a resin film. For example, a thermal head printer having a built-in thermal head is used.

Such a heat-sensitive recording material is capable of recording in a relatively short time with a relatively simple device without performing complicated processing such as development and fixing as compared with other recording materials, noise generation and environmental pollution. It has advantages such as lack of cost and low cost, and is used not only for copying books and documents but also as output recording paper for facsimiles, measuring instruments and the like.

However, such a heat-sensitive recording material is a color image obtained by a thermal reaction using a leuco dye and an acidic substance such as a phenolic substance or an organic acid as a developer, and various plasticizers used for rubber, plastics and the like. For example, when dioctyl phthalate, dibutyl phthalate, dihexyl phthalate, and dioctyl adipate permeate, there is a big problem that the color-developed portion is decolored. This problem is solved by providing a protective layer on the thermosensitive coloring layer with an aqueous emulsion of a water-soluble polymer or a water-insoluble resin, and it can be applied to POS labels for price tags used in supermarkets that could not be used in conventional thermosensitive recording materials. It has come to be used.

However, with the widespread use thereof, it has become clear that the recording part is discolored by water, alcohol, etc., or the white paper part is colored by vinegar.

On the other hand, the POS label printer is required to have a longer durability, and the printer is trying to have the durability by reducing the applied voltage and giving less energy. This is a demand for a recording material having a higher sensitivity than that of a heat-sensitive recording material.

However, there is no developer that is sufficiently sensitive to plasticizer resistance, alcohol resistance, etc.
A substance satisfying the alcohol resistance has a problem that high sensitivity cannot be obtained.

On the other hand, some leuco dyes have excellent record storability even when the object (plasticizer, alcoholic oil, etc.) comes into contact with the recording part, but on the contrary, there is a problem that the white paper part is colored by contact with vinegar. .

On the other hand, when the recording portion comes into contact with water, there is a problem in that the color developer is not water-insoluble and discoloration occurs in water.

(C) Objective The present invention provides a heat-sensitive recording material that is improved from the above-mentioned conventional drawbacks, that is, the fading of a recording portion due to a plasticizer, oils, alcohol, water, etc., or the blank portion due to contact with vinegar. An object of the present invention is to provide a heat-sensitive recording material which eliminates color development and has a sufficient color density with less applied energy.

(D) Means for Solving Problems According to the present invention, a thermosensitive coloring layer containing a leuco dye, a developer and a binder as main components is provided on a support, and a water-soluble layer is formed on the thermosensitive coloring layer. In the heat-sensitive recording material provided with a protective layer of the above-mentioned resin or an aqueous emulsion of a water-insoluble resin, 3- (N-cyclohexyl-N-methylamino) is used as the leuco dye.
-6-Methyl-7-anilinofluorane and bis (3-allyl-4-hydroxyphenyl) sulfone were used as the color developer, and 1,1,3-tris 3- was added to the thermosensitive coloring layer.
There is provided a heat-sensitive recording material characterized by containing t-butyl-4-hydroxy-6-methylphenyl) butane.

In the present invention, the use ratio of the leuco dye and the developer is generally 1 to 1 with respect to 1 part by weight of the leuco dye.
It is used in an amount of 0 part by weight, preferably 2 to 6 parts by weight.

The ratio of 1,1,3-tris (3-t-butyl-4-hydroxy-6-methylphenyl) butane to be used is generally 0.1-5 parts by weight, preferably 0.5-part by weight per 1 part by weight of the leuco dye. Used in 2 parts by weight.

In the present invention, in order to bond and support the leuco dye and the color developer on a support, various conventional binders can be appropriately used, and examples thereof include polyvinyl alcohol, starch and its derivatives, and methoxycellulose. Cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene Water-soluble polymer compounds such as / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer,
Polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene /
An aqueous emulsion of a water-insoluble resin such as an acrylic copolymer can be used. For the protective layer in the present invention, an aqueous emulsion of the above-mentioned aqueous polymer compound and water-insoluble resin is used.

Further, in the present invention, together with the leuco dye and the color developer, if necessary, an auxiliary additive component commonly used in this type of heat-sensitive recording material, such as a filler, a surfactant or a heat-fusible substance ( Alternatively, a lubricant) or the like may be used in combination. In this case, as the filler, for example, calcium carbonate, silica,
Zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic fine powder such as surface-treated calcium and silica, urea-formalin resin, styrene / methacrylic acid copolymer, Examples thereof include organic fine powders such as polystyrene resin. Examples of the heat-fusible substance include higher fatty acids or their esters, amides or metal salts, various waxes, aromatic carboxylic acids and amines. Condensates, benzoic acid phenyl esters, higher linear glycols, 3,4-epoxy-dialkyl hexahydrophthalates, higher ketones, and other heat-fusible organic compounds having a melting point of about 50 to 200 ° C. Can be mentioned.

Next, the present invention will be described in more detail with reference to examples. The parts and% shown below are based on weight.

Example 1 [Solution A] 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane 10 parts 10% hydroxyethyl cellulose aqueous solution 5 parts water 15 parts [Solution B] bis (3- Allyl-4-hydroxyphenyl) sulfone 25 parts 1,1,3-tris (3t-butyl-4-hydroxy-6-methylphenyl) butane 10 parts 10% aqueous polyvinyl alcohol solution 20 parts water 45 parts [C liquid] stearic acid Zinc 10 parts Calcium carbonate 40 parts 5% Methylcellulose aqueous solution 50 parts Water 50 parts [Solution D] Silica (Mizukasil P-527 manufactured by Mizusawa Chemical Co., Ltd.) 5 parts 10% PVA aqueous solution 150 parts 20% Zinc stearate emulsion (Hydrin Z manufactured by Chukyo Yushi-Seiya Co., Ltd. -7) 4 parts Each of liquids A to C in the mixture having the above composition has an average particle size of 2 μm or less. A solution was dispersed by the sea urchin a sand mill,
Solution B and solution C were prepared. On the other hand, the liquid D was prepared by mixing and stirring the above composition.

6 parts of solution A, 20 parts of solution B, 30 parts of solution C, 10%
70 parts of an aqueous polyvinyl solution and 25 parts of a 20% fatty acid amide emulsion (Hydrin M-7 made by Chukyo Yushi Co., Ltd.) were mixed and stirred to prepare a heat-sensitive coating liquid, and the dry coating amount was applied to a commercially available high-quality paper having a basis weight of 55 g / m ^2. A thermosensitive color-developing layer was obtained by coating with a wire bar so that the coating amount would be 6 g / m ² and drying.

Liquid D was applied on the heat-sensitive layer thus obtained so as to have a concentration of 2 g / m ² (solid content conversion) and dried to obtain the heat-sensitive recording material of the present invention.

Example 2 6 parts of solution A and 20 parts of solution B prepared in the same manner as in Example 1
Part, 30 parts of C liquid, 70 parts of 10% polyvinyl alcohol aqueous solution, and 25 parts of 20% methylol amide emulsion (Hydrin D-130 manufactured by Chukyo Yushi Co., Ltd.) were mixed and stirred to prepare a heat-sensitive coating liquid, and a basis weight of 55 g / dry coating weight to a commercially available wood free paper of m ² was obtained thermosensitive coloring layer was coated and dried with a wire bar so as to 6 g / m ^2.

Liquid D was applied on the heat-sensitive layer thus obtained so as to have a concentration of 2 g / m ² (solid content conversion) and dried to obtain the heat-sensitive recording material of the present invention.

Example 3 [Solution E] Bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts 2- (benzyloxy) naphthalene 25 parts 1,1,3-tris (3-t-butyl-4-hydroxy-6-) Methylphenyl) butane 10 parts 10% aqueous polyvinyl alcohol solution 30 parts water 85 parts As in Example 1, a mixture E was prepared by dispersing the mixture with a sand mill so as to have an average particle size of 2 μm or less.

Next, 6 parts of solution A, 35 parts of solution E, 30 parts of solution C, 10%
Polyvinyl alcohol aqueous solution 70 parts mixed and stirred thermosensitive coating solution was prepared, heat-sensitive color-developing layer by applying and drying a wire bar to a dry coating weight to a commercially available wood free paper having a basis weight of 55 g / m ² is 6 g / m ² Got

Liquid D was applied on the heat-sensitive layer thus obtained so as to have a concentration of 2 g / m ² (solid content conversion) and dried to obtain the heat-sensitive recording material of the present invention.

Example [F liquid] Bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts Dibenzyl terephthalate 25 parts 1,1,3-Tris (3-t-butyl-4-hydroxy-6-methylphenyl) butane 10 Parts 10% aqueous polyvinyl alcohol solution 30 parts water 85 parts Mixture having the above composition was treated in the same manner as in Example 1 to give an average particle size of 2
A solution F was prepared by dispersing with a sand mill so that the particle size became less than or equal to μ. Next, 6 parts of liquid A, 35 parts of liquid F, 30 parts of liquid C, 1
0% aqueous solution of polyvinyl alcohol were 70 parts of mixed and stirred thermosensitive coating solution was prepared by coating dried thermosensitive coloring a wire bar to a dry coating weight to a commercially available wood free paper having a basis weight of 55 g / m ² is 6 g / m ² Layers were obtained.

Liquid D was applied on the heat-sensitive layer thus obtained so as to have a concentration of 2 g / m ² (solid content conversion) and dried to obtain the heat-sensitive recording material of the present invention.

Comparative Example 1 Of the liquid A of Example 1, 3- (N-cyclohexyl-N-)
A heat-sensitive material was obtained in the same manner as in Example 1 except that 3-diethylamino) -6-methyl-7-anilinofluorane was used instead of methylamino) 6-methyl-7-anilinofluorane.

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

Comparative Example 3 [Solution G] Benzyl parahydroxybenzoate 25 parts 1,1,3-Tris (3-t-butyl-4-hydroxy-6-methylphenyl) butane 10 parts 10% aqueous polyvinyl alcohol solution 20 parts water 45 parts Liquid G was prepared by dispersing the mixture having the above composition in a sand mill so that the average particle diameter was 2 μm or less.

Next, 6 parts A solution, 20 parts G solution, 30 parts C solution, 10%
The heat-sensitive coating solution was prepared by 60 parts mixed with stirring polyvinyl aqueous solution, dry coating amount to a commercially available wood free paper having a basis weight of 55 g / m ² is 6 g /
A thermosensitive coloring layer was obtained by coating and drying with a wire bar so as to obtain m ² .

Liquid D was applied on the heat-sensitive layer thus obtained so as to have a concentration of 2 g / m ² (solid content conversion) and dried to obtain the heat-sensitive recording material of the present invention.

Using the thermal recording material obtained as described above as a sample, printing was performed using a label printer (manufactured by Ishida Hakari Co., Ltd.).
In addition, the following test was performed on each sample after printing in order to perform the reliability test of the image area.

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

(2) Alcohol resistance test The sample after printing was immersed in commercially available sake (special grade) for 24 hours, and the densities of the printed part and the blank part after the immersion were measured.

(3) Corrosion resistance test The sample after printing was immersed in commercially available vinegar (grain vinegar) for 24 hours, and the concentration of the printed part and the blank part after immersion was measured.

(4) Plasticizer resistance test Sample after printing and commercially available soft vinyl chloride (Dialap MS
-A) and contact it with a load of 300 g / m ² and
It was left for 72 hours under the condition of 0 ° C. and 65% RH, and the densities of the printed part and the blank part were measured. In addition, in all cases, the concentration was measured using a Masbeth densitometer RD-514 (Ratten No. 106).

The above results are shown in Table-1.

(E) Effect As is clear from the examples, the heat-sensitive recording material of the present invention does not cause discoloration of the recording portion due to contact with water, alcohol, plasticizer, etc., or coloring of the white paper portion due to contact with vinegar, and less application. It provides a heat-sensitive recording material which can obtain a sufficient color density with energy.

Claims (1)

[Claims] 1. A leuco dye, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, and a developer, bis (3-allyl-4-hydroxyphenyl) sulfone. Protecting a water-soluble polymer compound or an aqueous emulsion of a water-insoluble resin as a main component on a thermosensitive coloring layer containing 1,1,3-tris (3-t-butyl-4-hydroxy-6-methylphenyl) butane A heat-sensitive recording material having a layer.