JPS592889A - Diazo-based heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a diazo heat-sensitive recording material having a high chromogenic property and good storability by a method in which a diazo layer and a coupler layer are laminated on a supporter, in which the lower layer contains a heat-meltable substance and a binder and the layer other than the diazo layer contains a specific imidazole acid addition salt. CONSTITUTION:For example, a coating liquid composed of a diazo compound, a heat-meltable substance (e.g., N-stearylbenzamide, etc.), and a water-insoluble binder(e.g., vinyl chloride-vinyl acetate copolymer, etc.) and a coating liquid composed of a coupler (e.g., naphthol AS, etc.) and an imdazole acid addition salt (e.g., 1-cyanoethyl-2-dodecylimidazole-trimesic acid salt, etc.) of the formula (R<1> and R<2> are each H, phenyl, or benzyl and R<3> and R<4> are each H, an alkyl, or alkoxy, etc.) are orderly coated on a supporter and dried to obtain an objective recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, particularly a heat-sensitive recording material that can be photofixed.

That is, the present invention relates to a diazo-based thermosensitive recording material that develops color when recorded with a thermal head at a certain temperature, loses its ability to develop color in non-printed areas when further irradiated with light, and does not recolor when heat is applied again. It is.

Thermosensitive recording materials are used as copy paper for books, documents, etc., and are also used as output recording paper for computers, facsimile machines, medical measuring instruments, etc., and also as heat-sensitive recording label paper. In addition, heat-sensitive recording materials are also being considered for use as paper for creating securities, gift certificates, admission tickets, certificates, slips, etc. by taking advantage of their ease of automatic recording. In order to obtain high recording reliability, the heat-sensitive recording material must be able to be fixed.

Conventionally, as fixable heat-sensitive recording materials, diazo-based materials that utilize a color-forming reaction between a diazo compound and a coupler are known. However, from the standpoint of practicality, conventional products have not yet been satisfactory in terms of thermal response to thermal heads and long-term storage stability. In particular, in fields such as facsimile, there is a strong demand for high-speed recording performance (high-speed color development) in order to reduce information transmission costs, but conventional diazo-based products still cannot adequately meet these requirements. It didn't satisfy me.

By the way, in conventional diazo photosensitive paper, when carrying out a color reaction, it was possible to use aqueous ammonia or alkaline aqueous solution as a developer, and to adopt conditions that would allow a sufficient color reaction to occur, and the color reaction could also be caused by heating. It was possible to supply a sufficient amount of heat even when the process was carried out. Therefore, in the case of diazo-sensitive paper, no special measures were required to cause the color reaction to occur at high speed. However, in the case of a heat-sensitive recording material that performs a coloring reaction with a small amount of heat energy, such as a thermal head or a thermal pen, which is the object of the present invention,
Since the image forming means used in the case of diazo photosensitive paper cannot be used, various measures are required to efficiently cause a coloring reaction by using less thermal energy.

The present inventors have completed the present invention as a result of extensive research to develop a diazo-based heat-sensitive recording material that is different from the diazo-based heat-sensitive recording materials that have been proposed in the past, and has high color development and excellent long-term storage stability. I came to the conclusion.

That is, according to the present invention, a diazo layer containing a diazo compound as a main component and a coupler layer containing a coupler are laminated on a support, and the layer forming the lower layer of the diazo layer and the copper or plastic layer is laminated on a support. is a diazo-based thermosensitive recording material, which contains a thermofusible substance together with a water-insoluble binder, and further contains an acid addition salt of imidazole represented by the following general formula in a part of the coloring system other than the diazo layer. Materials provided.

Kyl group or cyanoalkyl group, R2 is hydrogen, phenyl, benzyl, amine group, hydroxyl group, cyan group, alkyl group, alkoxy group, halogen, or oxyalkyl group, R8 and R4 are hydrogen, It is an alkyl group, an alkoxy group, phenyl, benzyl, halogen, a nitro group or an oxyalkyl group. The carbon number of the alkyl group, cyanoalkyl group, alkoxy group and oxyalkyl group is usually 1 to 17.

Conventionally, it has been known to add inorganic or organic ammonium salts, urea, guanidine, imidazole, etc. to coloring systems in order to increase image density.

However, these basic additives still do not give satisfactory results in terms of long-term shelf life of products.

In order to improve long-term storage stability, it is desirable to use a substance that does not raise the pH of the coloring system at room temperature but can rapidly raise the pH of the coloring system when heated. Salt meets these needs and can increase the actual concentration without reducing long-term shelf life.

The acid addition salt of imidazole used in the present invention is a salt of imidazole and an organic or inorganic acid, and the basicity of imidazole is neutralized. When this acid addition salt of imidazole is heated, the acid decomposes or evaporates, resulting in a color-forming pH.
to rise. Specific examples of the acid addition salts of imidazole used in the present invention include the following.

imidazole benzoate, imidazole nitrate,
1-Methylimidazole-picrate, 1-phenylimidazole-vicrate, 2-methylimidazole-oxalate, 4-methylimidazole-nitrate, 1.4-
Dimethylimidazole-nitrate, 2-bromimidazole-nitrate, 4-bromimidazole-hydrochloride, 2-oxymethylimidazole-picrate, 4-oxymethylimidazole-hydrochloride, 2-phenylimidazole-isocyanurate, 1- Cyanoethyl-2-ethylimidazole-1-IJ mesinate, 1-cyanoethyl-
2-dodecylimidazole-trimesinate and the like.

In the heat-sensitive recording material of the present invention, the stacking order of the diazo layer and the coupler layer is arbitrary, but the layer forming the lower layer contains a thermofusible substance together with a water-insoluble binder to make the product hydrophobic. Improves long-term storage. In addition, some parts of the coloring system other than the diazo layer, such as a coupler layer, a support, an undercoat layer, an overcoat layer, an intermediate layer, or a thermofusible material layer provided as necessary, may include the above-mentioned The product contains an acid addition salt of imidazole to improve the actual density of the image formed during heating without impairing the long-term shelf life of the product. The amount of the acid addition salt of imidazole used is 05 to 10 parts by weight, preferably 1 to 5 parts by weight, per 1 part by weight of the diazo compound. In addition to the lower layer, the thermofusible substance can be contained in the upper layer, if necessary, and can be laminated as an independent layer.

The diazo compound and coupler used in the present invention are those commonly used in diazo photosensitive paper, and include, for example, those shown below.

Diazo compound: As the diazo compound used in the present invention, commonly used ones, such as those represented by the following general formula5, can be used.

R1 11+g However, in general formulas [1), [2) and [3],
Tow.

R6, R@u Hydrogen, halogen, C1-C5 alkyl"v, R8, R91d, hydrogen, halogen, C1-C
5 alkyl group or alkoxyl (M, R4, R5 are the same or different C1 to C5 alkyl group, hydroxy 01 to C3 alkyl group or alkoxyl group, or halogen); Methyl group, C1-C5 alkyl group or ("14 +
"15 + 6: Same as 8), M, , M2. M8 is an acid residue or an acid residue forming a double salt with a metal salt.

It is. In this case, the acid residues include halogen ions and B
It is preferable to use a fluorine-containing inorganic acid ion such as F;

5nCt2, etc.

Specific examples of those corresponding to general formula [1] include the following.

Specific examples of those corresponding to general formula [2] include the following.

Specific examples of those corresponding to general formula [3] include the following.

CH8 In the present invention, in order to obtain a product with further improved long-term shelf life, HBF4 and HPF'6 are used as the diazo compound.
Advantageously, they are used in the form of water-insoluble salts such as fluorine-containing salts.

Coupler m: Couplers used in the present invention include phenol, resorcin, methylsorcin, 4,4-bisresorcin, phloroglucin, resorcinic acid, phloroglucinic acid, 2-
Methyl-5-methoxy-1゜3-dihydroxybenzene, 5-methoxy-13-dihydroxybenzene, 4-N
, N-dimethylphenol, 2.6-dimethyl-1.3
．． 5-trihydroxybenzene, 2,6-cyhydroxybenzoic acid, 2,6-cyhydroxy-3,5-dibromo-
Phenol derivatives such as 4-methoxybenzoic acid 1, α-
Naphthol, β-naphthol, 4-methoxy-1-naphthonope 2,3-dihydroxynaphthalene, 2,3-dihy, droxynaphthalene-6-sodium sulfonate, 2-
Hydroxy-3-propylmorpholinonaphthoic acid, 2-
Hydroxy-3-naphtho-o-toluicide, 2-hydroxy-3-naphthoic acid morpholinopropylamide, naphthol derivatives such as naphthol A8, acetoacetanilide, 4-benzoylamino-2,5-jethoxyacetoacetanilide, N-acetoacetate Octadecylamine, N,N'-bis(acetoaceto)decane-1,1o-
Active methylene compounds such as diamine and 2,4.6-dolipromoacetoacetanilide may be mentioned, but are not limited to these, and any compound that can act as a coupler for the diazo compound may be used. Applicable.

In the present invention, a thermofusible substance is used to enhance rapid color development. Specific examples of such things include, for example, the following:

Alcohol derivatives such as 2-tribromoethanol, 2,2-dimethyltrimethylene glycol, 1,2-cyclohexanediol, acid derivatives such as malonic acid, glutaric acid, maleic acid, methylmaleic acid, beeswax, shellac wax, etc. Animal waxes, vegetable waxes such as carnauba wax, mineral waxes such as montan wax,
Petroleum waxes such as halaffin wax and microcrystalline wax, other synthetic waxes such as higher fatty acid polycompounds,
Synthetic paraffin, chlorinated paraffin, metal salts of higher fatty acids, higher linear glycols, dinalkyl 3,4-epoxyhexahydrophthalate, etc.

The thermofusible substance used in the present invention preferably has a melting point or softening point in the range of 50 to 250C.

If the melting point or softening point is less than 50 parts, the shelf life of the product tends to be poor, and if it exceeds 250C, the thermal response of the product to the thermal head becomes unsatisfactory. In addition, from the viewpoint of obtaining a product with high-speed coloring property (high-speed recording property), these thermofusible substances used in the present invention should be used in an amount of 1 to 30 parts by weight, preferably 2 to 10 parts by weight, per 1 part by weight of the diazo compound. Used as a percentage. If this amount exceeds the above range, color development will be insufficient and the resulting product will be unsuitable as a recording material for high-speed recording. In the case of the present invention, it is particularly preferable to use 2 parts by weight or more for high-speed output recording such as facsimile. On the other hand, if the amount added is too large, blurring of the image may occur during color development by heating, which is not preferable. Therefore, in the case of the present invention, the amount of the thermofusible or thermosoftening substance added is preferably kept within the above range.

Further, in the present invention, the heat-sensitive coloring layer may further contain acidic substances, basic substances, fillers, and other substances as auxiliary components, if necessary.

Acidic substance: An acidic substance is added as necessary to prevent a coupling reaction and for storage stability, and examples thereof include the following.

Tartaric acid, citric acid, boric acid, lactic acid, gluconic acid, sulfuric acid, etc.

Filler: A filler is added to improve the matching property to a thermal head when heating is performed by a thermal head, etc., and examples of such fillers include the following.

Organic and inorganic solid particles such as rum, calcium carbonate, titanium, talc, kaolin, silica, alumina, etc.

Other auxiliary ingredients include zinc chloride, zinc sulfate, sodium citrate, guanidine sulfate, calcium gluconate, and a water-insoluble binder (binder) used to form an aqueous layer to suppress or assist color development. is polyester, polystyrene, pum chloride, polyvinyl acetate, polyvinyl chloride, polybutadiene, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutadiene,
Styrene/butadiene/acrylic copolymer, polyethylene, ethylene/vinyl acetate copolymer, styrene/acrylic copolymer, polyvinylidene chloride, vinylidene chloride/acrylic copolymer, phenolic resin, urea/formalin resin, melamine resin, etc. Organic solvent soluble or water dispersible resins can be used.

In addition to the above-mentioned organic solvent-soluble or water-dispersible resins, binders used in other layers include polyvinyl alcohol, polyacrylamide, casein, gelatin, starch and its derivatives, polyvinylpyrrolidone, and carboxymethyl cellulose. , methylcellulose, ethylcellulose, styrene-maleic anhydride copolymer, in(or diiso)butylene-maleic anhydride copolymer, and other water-soluble resins can also be used.

Examples of the support used in the present invention include a paper base, a plastic film, and a base obtained by precoating paper with a synthetic resin, filler, or the like.

Next, the present invention will be explained in detail using examples.

Example 1 An aqueous dispersion containing 15 parts of polyvinyl alcohol and 05 parts of calcium carbonate was coated on the surface of a high-quality paper weighing 50 νI and dried to form an undercoat layer with a coating weight of 2 ft/lrl. A methylcerunlube dispersion consisting of the following ingredients was applied on top of it and dried to obtain a coating amount of 3.35 fl.
A diazo layer of /i was provided.

N-Stearylbenzamide 10 parts Vinyl chloride-vinyl acetate copolymer 20 parts Next, an aqueous dispersion of the following components was applied onto the diazo layer and dried to form a single layer of coupler with a coating weight of 2.4 νI. The surface was calendered to a Bekk smoothness of 400 seconds to obtain a heat-sensitive recording material.

Naphthol A8 o, 5 parts silica
0.5 part methylcellulose
0.5 parts Next, this heat-sensitive recording material was printed using a commercially available high-speed recording facsimile machine, and then irradiated with ultraviolet rays using a commercially available diazo copying machine to fix it. A clear black image was obtained. The image density of this product was 100 using a Macbeth densitometer. Also, this thermal paper before printing is 40U-
Although it was left in an environment of 904R,H for 24 hours, the skin concentration only increased by 005. Also, 6 o U −
The increase in skin area after being left in the dryRH environment for 24 hours was o, io, and 2! the law of nature.

Examples 2 to 5 The actual concentration and storage stability were investigated in the same manner as in Example 1 except that 1-cyanoethyl-2-dodecylimidazole-trimesinate in Example 1 was replaced with the compound shown below. The results are shown in Table-1.

Comparative Examples 1 to 3 The actual concentration and storage stability were investigated in the same manner as in Example 1 except that 1-cyanoethyl-2-dodecylimidazole-trimesinate in Example 1 was replaced with the compound shown below. The results are shown in Table-2.

Table-2 Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) A diazo layer containing a diazo compound as a main component and a coupler layer containing a coupler are laminated on a support, and a thermofusible material is used for the lower layer of the diazo layer and the coupler layer. A diazo-based heat-sensitive recording material, characterized in that it contains a water-insoluble binder together with a water-insoluble binder, and further contains an acid addition salt of imidazole represented by the following general formula in a part of the coloring system other than the diazo layer. 3 R'' (wherein R1 is hydrogen, phenyl, benzyl, alkyl group, or cyanoalkyl group R2 is hydrogen, phenyl, benzyl, amino group, hydroxyl group, cyano group, alkyl group, alkoxy group, halogen or oxyalkyl group basis,
R'', I't4 is hydrogen, alkyl group, alkoxy group, phenyl, benzyl, haloken, nitro group or oxyalkyl group)