JPH0225353B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-sensitive recording material, and more specifically, the present invention relates to a heat-sensitive recording material, and more specifically, a heat-sensitive color-forming layer containing as main components a color-forming substance that is usually colorless or slightly light-colored and a color-developing substance that causes the color-forming substance to develop color when heated is provided on a support. The present invention relates to improvements in heat-sensitive recording materials having a different structure. Generally, heat-sensitive recording materials are manufactured by coating and drying a heat-sensitive coloring layer forming liquid containing a coloring component that can cause a coloring reaction when heated, on a support such as paper, synthetic paper, or synthetic resin film. and
A colored image can be recorded on the surface of the heat-sensitive recording material thus obtained by heating it with a thermal pen or a thermal head. In such conventional heat-sensitive recording materials, when heated during recording, components in the heat-sensitive coloring layer melt and stick to the thermal head or thermal pen (dregs adhesion).
Problems with paper feeding may occur, causing statesking phenomenon, sticky substances may be transferred to the recording material, causing trailing, and sticky substances may accumulate, reducing the clarity of colored images or causing distortion. There were some problems, such as it becoming the cause of the problem. The properties of these heat-sensitive recording materials that are problematic when heated with a thermal head or pen are called head matching properties, and are extremely important when considering the quality of heat-sensitive recording sheets. One way to improve the head matching properties of heat-sensitive recording materials is to include metal salts of fatty acids in the heat-sensitive coloring layer, but although this method is effective in reducing statesking, it often results in scum adhesion.
This causes problems such as tailing and sharpening of the bottom of the image. Also,
There is a method of containing polyethylene wax or the like. In the case of this method, it is effective in improving the adhesion of residue, trailing, and blurring of the image, but the blurring of the image deteriorates. As described above, the conventional techniques have not achieved sufficiently satisfactory results in improving both head matching properties and image blurring. An object of the present invention is to solve the above-mentioned conventional drawbacks, and more specifically, to provide a heat-sensitive recording sheet that has excellent head matching properties with a thermal head or a thermal pen, and is free from image smearing. In view of the purpose of the present invention, the present inventors have conducted various studies and found that the main ingredients are a normally colorless or slightly pale color-forming substance and a color-developing substance that causes the color-forming substance to develop color when heated. In a heat-sensitive recording material having a structure in which a heat-sensitive coloring layer containing as is provided on a support,
A higher fatty acid and a metal salt of a higher fatty acid are contained in the heat-sensitive coloring layer, and the ratio of the higher fatty acid is 1 to 1.
It has been found that the object of the present invention can be achieved by using 1 to 5 parts by weight of the higher fatty acid metal salt per part by weight, and the present invention has been completed. The heat-sensitive recording material of the present invention has excellent head matching properties and no bleeding in the colored image, so it has excellent color development in both recording density and sharpness even during long-time recording and high-speed recording. You can get the image. The recording material of the present invention will be explained in more detail below. As the color-forming substance, color developer, and binder to be contained in the heat-sensitive coloring layer, various substances commonly used in this type of field can be used, but as the color-forming substance, triphenylmethane type, Fluorane-based, phenothiazine-based, auramine-based, and spiropyran-based leuco substances are particularly preferred, and as the color developer, any organic acidic substance can be used, but phenolic acidic substances are particularly preferred. As the binder, it is preferable to use water-soluble polymers and emulsion type binders generally used in the field of paper processing. As the filler, both inorganic and organic fillers commonly used in the field of paper processing can be used. Specific examples of these will be shown below. Color-forming substance: 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-
Bis(p-dimethylaminophenyl) phthalide, 3,3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide, 3,3-
Bis(p-dimethylaminophenyl)-6-chlorophthalide, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-(N-phenylamino)fluoran, 3-diethylamino-7
-Chlorofluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-
8'-Methoxybenzoindolino-pyrylospirane, benzoic acid lactam, 2-[3,6-bis(diethylamino)-9-(o-chloroanilino)
xanthyl] color developer; α-naphthol, β-naphthol, 4-t-
Butylphenol, 4-t-octylphenol, 4-phenylphenol, 2,2'-bis(p-hydroxyphenyl)propane, 2,
2'-bis(p-hydroxyphenyl)butane,
4,4'-cyclohexylidene diphenol,
2,2'-bis(2,5-dibromo-4-hydroxyphenyl)propane, 4,4'-isopropylidene bis(2-t-butylphenol), 2,
2'-methylenebis(4-chlorophenol) Binder; Polyvinyl alcohol, starch, starch derivative, methylcellulose, hydroxyethylcellulose, polyacrylate, polyvinylpyrrolidone, gum arabic, casein, polyacrylic acid copolymer, styrene-maleic anhydride Examples include water-soluble resins such as copolymers, isobutylene-maleic anhydride copolymers, and water-insoluble resins such as styrene-butadiene emulsions, polyvinyl acetate emulsions, and styrene-acrylic acid ester copolymer emulsions. As fillers, all inorganic and organic fillers used in the field of ordinary paper processing can be used, such as clay, talc, kaolin, titanium oxide, zinc oxide, calcium carbonate, Examples of fine particles include aluminum oxide, urea-formalin resin, polystyrene, and phenol resin. The proportions of each component used in the heat-sensitive coloring layer are as follows: 3 to 30% by weight of the color-forming substance, 5 to 60% by weight of the color-developing substance, 3 to 30% by weight of the binder, and 5% by weight of the filler. The proportion is such that it accounts for ~60% by weight. In the present invention, in addition to the above-mentioned conventional heat-sensitive coloring layer forming components, in order to obtain a heat-sensitive recording material that has excellent head matching properties and does not cause blurring of colored images, metal salts of higher fatty acids and It uses higher fatty acids as an essential ingredient. Specific examples of these are as follows. Higher fatty acids; saturated higher fatty acids such as palmitic acid, myristic acid, stearic acid, behenic acid, and cerotic acid; unsaturated higher fatty acids such as lycanic acid and parinaric acid. Higher fatty acid metal salts: calcium palmitate, calcium stearate, zinc stearate, magnesium stearate, calcium myristate, magnesium oleate, aluminum behenate, etc. In the present invention, it is necessary to use the above-mentioned higher fatty acid and a metal salt of a higher fatty acid together, and to use the higher fatty acid in a proportion of 1 to 5 parts by weight of the higher fatty acid metal salt per 1 part by weight of the higher fatty acid. As a result of such specification, the heat-sensitive recording material of the present invention provides clear recorded images without causing deposits, staining, trailing, or image blurring, as is clear from the examples described later. Such effects will not be realized unless the above requirements are met. The total amount of higher fatty acids and metal salts of higher fatty acids used is 0.2 to 20 parts by weight, preferably 1 to 5 parts by weight, per 1 part by weight of the coloring agent. In order to obtain the heat-sensitive recording material of the present invention, commonly known methods can be used. That is, higher fatty acids and higher fatty acid metal salts according to the present invention, and conventional color-forming substances, color-developing substances, binders, and other additives are used alone or in combination except for the color-forming substances, and polyvinyl alcohol, etc. It is added to an aqueous medium together with a protective colloid substance, a surfactant, etc., and dispersed using a dispersing machine such as a ball mill, attritor, or sand mill. Next, each dispersion liquid is mixed to prepare a thermosensitive coloring layer forming liquid, and this is applied to paper,
It is applied onto a support such as synthetic paper or plastic film and dried. The heat-sensitive recording material of the present invention obtained in this way has no problems such as states king, scum adhesion, etc.
It has excellent thermal response without trailing or image blurring. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A mixture consisting of the following formulation was milled using a magnetic ball mill.
The mixture was ground for several days to prepare liquids [A], [B], [D], and [E]. [A] Liquid 2-{N-(3'-trifluoromethylphenyl)
amino}-6-diethylaminofluorane
150 parts by weight 5% polyvinyl alcohol aqueous solution 150 〃 Water 200 〃 [B] Solution Calcium carbonate 100 parts by weight 5% methylcellulose aqueous solution 100 〃 Water 200 〃 [D] Solution Calcium stearate 80 parts by weight 5% methylcellulose aqueous solution 80 〃 Nonionic surfactant Agent 2 Water 238 Liquid [E] Behenic acid 80 parts by weight 5% methylcellulose aqueous solution 80 Nonionic surfactant 2 Water 238 In addition, a mixture consisting of the following formulation was pulverized for 2 hours using an experimental attritor. Solution [C] was prepared. [C] Liquid 2,2-bis(p-hydroxyphenyl)propane 120 parts by weight 5% polyvinyl alcohol aqueous solution 120 Water 160 Next, use the above liquids [A] to [E] and 20% polyvinyl alcohol aqueous solution as follows. Prepare a coating liquid for the heat-sensitive coloring layer, and apply it to a commercially available high-quality paper with a standard basis weight of 53 g/m ² using a wire bar so that the dry coating amount is 7 g/m ² . Dry to form a heat-sensitive coloring layer. Then, the heat-sensitive recording material of the present invention was obtained by calendering so that the smoothness was 200 to 400 seconds. Thermosensitive coloring layer coating liquid: [A] 10 parts by weight [B] 40 [C] 30 [D] 20 [E] 20 20% polyvinyl alcohol aqueous solution 30 [Example 2] [D] solution in Example 1 Prepared by using zinc stearate instead of calcium stearate and palmitic acid instead of behenic acid in [E] solution,
A heat-sensitive coloring layer coating solution having the following composition was prepared using the obtained liquids [F] and [G] and an oxidized starch aqueous solution as a binder, and then the heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1. . Thermosensitive coloring layer coating solution: [A] 10 parts by weight [B] solution 40 [C] solution 30 [F] solution 15 [G] solution 15 〃 20% oxidized starch aqueous solution 40 〃 Comparative example 1 Example 1 A comparative heat-sensitive recording material was obtained in the same manner as above except that liquids [D] and [E] were not added. Comparative Example 2 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1 except that liquid [E] was not added. Comparative Example 3 A comparative heat-sensitive recording material was obtained in the same manner as in Example 2, except that liquid [F] was not added. Printing was performed on the heat-sensitive recording material obtained as described above using a heat-sensitive facsimile receiver equipped with a built-in thin-film thermal head, and tests were conducted for scum adhesion, statesking, trailing, image blurring, and print density (thermal responsiveness).
The results are shown in Table 1, and the order of occurrence of each phenomenon other than print density is ◎, 〇,
Evaluation is made on a four-level scale of △ and ×, of which ◎ indicates that it hardly occurs, and △ and × indicate that it is a problem in practical use.

[Table] As is clear from the above table, the product of the present invention can obtain images with high density without causing the phenomenon of dust adhesion, states king, trailing, or image blurring.
It can be seen that this is superior to the comparative example.

Claims (1)

[Claims] 1. A heat-sensitive recording material having a structure in which a heat-sensitive color-forming layer containing as main components a color-forming substance and a color-developing substance that causes the color-forming substance to develop color when heated is provided on a support, in which a higher fatty acid is contained in the heat-sensitive color-forming layer. and a metal salt of a higher fatty acid, and the ratio of the metal salt of the higher fatty acid is 1 to 5 parts by weight per 1 part by weight of the higher fatty acid.