JPH042116B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermochromic recording material with improved storage stability. More specifically, the recording layer formed on the support contains a coupler compound via a binder, a p-phenylenediamine compound that reacts with the compound to form a dye, and an amount necessary for the reaction to occur. 4 of a base generating substance capable of supplying a base and a reaction accelerator for promoting the reaction.
In a recording material consisting of an oil-based or water-based polymer compound, a layer containing a base generating substance is formed on a separation layer formed of an oil-based or water-based polymer compound via a binder made of an oil-based or water-based polymer compound. Further, on each outer surface, any one component of the color-forming component-containing layer consisting of a coupler compound, a p-phenylenediamine compound, and a reaction accelerator is separated from the remaining components by the two layers. It has storage stability due to its multi-layered structure.
It is a thermochromic recording material that develops color with high density. As is well known, methods that utilize thermal energy for color development include (a) heat-sensitive recording materials that utilize the reaction between leuco dyes and acidic substances, and (b) diazo recording materials that utilize the reaction of aromatic diazo compounds and coupler compounds. type thermosensitive recording material. All of these recording materials have an advantage in that they use a primary color development method, but in the case of (a), the printed image lacks fixation properties, so the disadvantage is that long-term fixation of the image cannot be expected. Therefore, there has been a demand for ways to improve this point. In addition, in the case of (b), since the system is unstable, the coloring reaction progresses easily and background coloring is likely to occur.As a preventive measure, the diazo compound and the coupler compound are separated from each other to allow the coloring reaction to proceed. It is necessary to prevent Various separation methods for this purpose have been proposed and are known, but all of them have various practical difficulties, and the reality is that they have not yet been put into practical use. Therefore, as a result of various studies to solve the above-mentioned points, the present inventors have found that the above-mentioned drawbacks can be solved by developing color using a so-called coupling reaction in which a coupler compound and a p-phenylenediamine compound react. They discovered this and completed the present invention. That is, in the coupling reaction in the present invention, a coupler compound as a coloring component is coupled with a p-phenylenediamine compound that forms a dye, a basic substance that increases the pH of the system and promotes the coupling reaction, and A reaction accelerator is required to promote the reaction, but even if any one of the four components is missing, the coloring reaction will not occur. A base-generating substance-containing layer containing a base-generating substance is formed on a separation layer formed of a polymeric compound via a binder made of an oil-based or water-based polymeric compound, and the separation layer and the base-generating substance are further added to the separation layer and the base-generating substance. On each outer surface of the containing layer, any one component of the color-forming component containing layer consisting of a coupler compound, a p-phenylenediamine compound, and a reaction accelerator is separated from the remaining components by the two layers. This is a thermochromic recording material that is formed into multiple layers to further improve its storage stability as a recording material. Therefore, the thermochromic recording material thus obtained is
After forming this on a suitable support (described later), when printing is performed on the surface of the recording material through a thermal head, the portion of the separation layer softens or melts due to the thermal head, softening or fusing the coloring components in the recording material. , the pH of the system is raised by the action of a base generating substance to cause a coupling reaction, and at the same time, the reaction proceeds quickly and in a short time by the cooperative action of a reaction accelerator, resulting in color development at a high concentration. Since the colored images obtained in this way are based on colored dyes synthesized through a coupling reaction, the images once formed do not fade, are stable over a long period of time, and are compatible with recording materials. In the uncolored area, the separation layer remains intact and maintains its original structure, so the area containing the coloring component does not develop background color and maintains the desired good storage stability over a long period of time. It is possible. As described above, the present invention has the advantage of providing a thermochromic recording material with improved storage stability, and its practical effects on related industries are particularly highly evaluated. Examples of materials that can be used in the present invention are as follows: (1) Binder: starch and its derivatives, gelatin, casein,
Examples include polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, and acrylamide. (2) Coupler compounds: - Cyan color-forming couplers include α-naphthol and its derivatives, phenol and its derivatives, etc. Yellow color-forming couplers include acylamide-type compounds represented by acetoacetanilide, and diacylmethane-type compounds represented by dibenzoylmethane. Compounds such as aldehyde compounds represented by benzaldehyde and glutaraldehyde are used as magenta coloring couplers such as pyrazolone type compounds represented by 1-phenyl-3-methyl-5-pyrazolone, α-
Examples include acylacetonitrile type compounds represented by cyanoacetophenone, benzyl cyanide and derivatives thereof. (3) p-phenylenediamine compound: -N,N-dimethyl-p-phenylenediamine,
N,N-diethyl p-phenylenediamine, 4-
Amino-N-ethyl-N-(β-hydroxyethyl)-aniline, 4-amino-3-methyl-N-
Diethylaniline, 4-amino-3-methyl-N
-ethyl-N-(β-hydroxyethyl)-aniline, 4-amino-3-methyl-N-ethyl-N-
Examples include sulfates and hydrochlorides such as (β-methanesulfonamidoethyl)-aniline. (4) Base generating substances: - Imidazole and its derivatives, amide compounds represented by urea or benzamide, guanidine compounds represented by guanidine, aniline compounds represented by aniline, etc. are exemplified. In addition, sodium and potassium salts of organic acids are also used to raise the PH of the system by heating. (5) Reaction accelerator: − Ca, Mg, Al, Zn, Fe, Ni, Sn, Pb, Cu,
Metal oxides and sulfides such as Ag, Pt, Au, Co, and Ti,
Examples include halides, sulfates, nitrates, carbonates, and organic acid salts. Furthermore, peroxides of organic compounds can also be used as reaction promoters. (6) Separation layer materials: - polyvinyl chloride, polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, polyester, polystyrene, nylon, acrylic, acrylonitrile, polyamide, polyurethane, polyvinyl butyral, ethyl cellulose, cellulose acetate butyrate, Examples include the above-mentioned thermoplastic polymer compounds that lose separation performance by softening or melting upon heating, such as polyvinyl alcohol and hydroxyethyl cellulose, and these may be either oil-based or water-based. (7) Materials added to the base-generating substance-containing layer: - A thermoplastic polymer compound that softens or melts when heated, and is soluble in a solvent such as methanol, ethanol, or water that dissolves the base-generating substance. The following substances are exemplified. polyvinyl butyral, nylon, acrylic,
Ethylcellulose, nitrocellulose, cellulose acetate, propionate, polyvinyl alcohol, hydroxyethylcellulose, etc. (8) Support: - General paper such as high-quality paper and coated paper, film made of synthetic polymer compounds such as polyester, polyamide, and nylon, and a laminated structure in which resin or metal is laminated to synthetic paper, paper, or plastic film. Examples include sheets such as Furthermore, in addition to the above-mentioned materials, the present invention also uses thermofusible substances to improve color development sensitivity, organic and inorganic pigments to improve matching with a thermal head, and materials to improve coating properties of paint. Therefore, it is also possible to use a surfactant or the like in the coating liquid. In addition, thermofusible substances include alcohol derivatives such as 2-tribromoethanol and 2,2-dimethyltrimethylene glycol, organic acid derivatives such as malonic acid and glutaric acid, metal salts of higher fatty acids, higher amides, and combinations of fatty acids and amines. and other waxes. Furthermore, examples of pigments that can be used include kaolin, talc, silica, alumina, titanium, calcium carbonate, aluminum hydroxide, magnesium carbonate, zinc oxide, styrene resin particles, and urea-formalin condensation resin particles. FIG. 1 shows an enlarged longitudinal section (thickness direction) of the thermochromic recording material of the present invention formed on a support, in which 1 is a support such as paper or plastic;
and 5 is a layer containing a coloring component, 3 is a separation layer consisting of an oil-based and water-based polymer compound, and 4 is a base-generating substance-containing layer. In the above configuration, the amounts of the binder, coupler compound, p-phenylenediamine compound, base generating substance, and reaction promoter used are as follows. However, all "parts" shown here indicate "parts by weight." Coupler compound: Usually 0.1 to 10 parts per 10 parts of binder, preferably 2 to 4 parts p-phenylenediamine compound: Usually 0.1 to 10 parts per 10 parts of binder, preferably 2 to 4 parts Base generator: Usually 1 part per 10 parts of binder ~40 parts preferably 10
~20 parts Reaction accelerator (water soluble): Usually 0.1 to 10 parts per 10 parts of binder, preferably
0.1 to 1.5 parts Reaction accelerator (water-insoluble): Usually 5 to 50 parts, preferably 10 parts per 10 parts of binder
~20 parts (dispersed in water in the form of fine particles) In addition, the coating amount of each layer in the present invention is usually 1 to 10 g/m 2 and preferably 1 to 3 g/m ² for the coloring component-containing layer.
m ² , usually 1 to 10 g/m ² in the separation layer, preferably 1 to 3
g/m ² , 1 to 10 g/m ^{2 ,} preferably 1 to 3 g/m ² in the base generating substance-containing layer. The present invention will be explained in more detail with reference to Examples (including comparative examples) below. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight," respectively. Example 1 [Liquid A] N,N-diethyl-p-phenylenediamine sulfate 1.5 parts Polyvinyl alcohol (5% aqueous solution) 100 parts The above composition was stirred, and N,N-diethyl-p-
Solution A was prepared by dissolving phenylenediamine. [Liquid B] Polyester 20 parts Toluene/ethyl acetate (3/1) mixed solvent 80 parts The above composition was stirred and the polyester was dissolved to prepare Solution B. [Liquid C] Polyvinyl butyral 15 parts Guanidine 6 parts Ethanol 85 parts The above composition was stirred to dissolve polyvinyl butyral and guanidine to prepare Solution C. [Liquid D] α-naphthol (dissolved in ethyl phthalate)
1.4 parts Copper sulfate 0.5 parts Stearic acid amide 3.0 parts Calcium carbonate 4.0 parts Polyvinyl alcohol (5% aqueous solution) 100 parts A mixture having the above composition was dispersed in a ball mill for 16 hours to prepare Solution D. Solutions A to D obtained as described above were sequentially applied to the resin film surface of polyethylene laminated paper whose surface had been subjected to corona treatment. To do this, first apply liquid A on the support so that the coating amount after drying is 3 g/m ² , dry it with air at 60°C, and then apply liquid B on the top surface in the same manner as above at a rate of 3 g/m ² Then blow dry at 60℃. Next, apply liquid C on the top surface in the same manner as above.
After applying g/m ² and drying with air at 60°C, further apply 3 g/m ² of liquid D on the upper surface and drying with air at 60°C. In this way, a recording paper in which a thermochromic recording material having a four-layer structure was formed on a support was obtained. Comparative Example 1 Liquids A, C and D prepared in Example 1
The liquid was sequentially applied to the resin film surface of a polyethylene laminate paper whose surface had been subjected to corona treatment in the same manner as in Example 1 to obtain a recording paper having a three-layered recording material. Comparative Example 2 [Liquid E] Polyester 20 parts Guanidine 6 parts Toluene/ethyl acetate (3/1) mixed solvent 80 parts A mixture having the above composition was dispersed in a ball mill for 24 hours to prepare Liquid E. The A solution prepared in Example 1, the above E solution, and the D solution prepared in Example 1 were sequentially added to Example 1.
A recording paper was obtained in which a three-layer recording material was formed by coating the resin film surface of a polyethylene laminate paper whose surface had been subjected to a corona treatment in the same manner as in the case of . Comparative Example 3 [Liquid F] N,N-diethyl-p-phenylenediamine sulfate 1.5 parts Guanidine 6 parts Polyvinyl alcohol (5% aqueous solution) 100 parts A mixture of the above composition was stirred and N,N-diethyl-
Solution F was prepared by dissolving p-phenylenediamine sulfate and guanidine. The above F solution, B solution and D solution prepared in Example 1 were sequentially added in the same manner as in Example 1.
A recording paper was obtained in which a three-layer recording material was formed by coating the resin film surface of a polyethylene laminate paper whose surface had been subjected to a corona treatment. Comparative Example 4 [Liquid G] 6 parts of guanidine was added to Solution D of Example 1 and dispersed in a ball mill for 16 hours to prepare Solution G. Solution A, solution B, and solution G prepared in Example 1 were sequentially applied in the same manner as in Example 1 to the resin film surface of polyethylene laminate paper whose surface had been corona-treated to obtain a three-layer structure. A recording paper on which a recording material was formed was obtained. Table 1 shows the coloring density of the thermochromic recording material obtained as described above and the results of the storage test before and after coloring.

[Table] As explained above, in the present invention, a base-generating substance-containing layer is formed on a separation layer, and a layer (color-forming component-containing layer) in which color-forming components are separated from each other is provided on the outer surface of the base-generating substance-containing layer via the two layers. Since it is a thermochromic recording material having a four-layer structure, it has particularly good storage stability and can develop color at high density, so that when it is formed on a support, a recording paper having the above characteristics can be obtained. It is something that can be done.

[Brief explanation of drawings]

The drawing shows an example of the present invention, and is an enlarged vertical cross-sectional (thickness direction) sectional view when the present invention is formed on a support. 1... Support, 2, 5... Coloring component-containing layer, 4
...Base-generating substance-containing layer.

Claims (1)

[Claims] 1. A coupler compound contained via a binder in the recording layer formed on the support, a p-phenylenediamine compound that reacts with the coupler compound to form a dye, and an amount necessary for the reaction to occur. A recording material containing four components: a base generating substance capable of supplying a base of It consists of a base-generating substance-containing layer containing a base-generating substance contained through a binder made of an oil-based or water-based compound, and furthermore, a color forming layer consisting of a coupler compound, a p-phenylenediamine compound, and a reaction accelerator on each outer surface. 1. A thermochromic recording material characterized in that the component-containing layer is formed in multiple layers such that any one of the components is separated from the remaining components by the two layers.