JPH0240515B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-sensitive recording material, and more particularly to a fixable diazo-based heat-sensitive recording material. Conventionally, as heat-sensitive recording materials, there are those that produce heat-sensitive coloring by using a reaction between an organic metal salt and a reducing agent, and those that produce heat-sensitive coloring by using a reaction between a leuco dye and an acidic substance. ing. However, such heat-sensitive recording materials have the disadvantage that recorded images cannot be fixed because they are non-fixable. That is, in the case of such a non-fixable heat-sensitive recording material, it is possible to perform recording again by performing another thermal printing after once recording by thermal printing. Therefore, the above-mentioned heat-sensitive recording materials have the risk of falsifying the information recorded thereon.
The reliability of records is low, and it cannot be applied to fields where reliability is required, such as recording or creating necessary items for securities, gift certificates, admission tickets, certificates, slips, etc. Further, in the case of such recording materials, if they are exposed to an environment of 70° C. or higher, the entire surface develops color, which causes the problem that the recording cannot be read. In particular, heat-sensitive recording materials that utilize the reaction between leuco dyes and acidic substances have the disadvantage that recorded information is erased when they come into contact with organic solvents or plasticizers in plastics. These drawbacks are due to the fact that these heat-sensitive recording materials are non-fixable. On the other hand, so-called diazo photosensitive paper, which utilizes the reaction between a diazo compound and a coupler, is widely known as a fixable recording material.
In this diazo photosensitive paper, by irradiating the unreacted diazo compound with light after image formation, it can be photodecomposed and fixed. Conventionally, heat-sensitive recording materials have been known in which the reaction between a diazo compound and a coupler is carried out by heating. This diazo-based heat-sensitive recording material has a heat-sensitive recording layer containing a diazo compound and its coupler as the main reaction components on a support, and one of the components in the heat-sensitive recording layer is formed as discontinuous particles. It is isolated from other components to prevent the color reaction from proceeding. However, all of the conventional ones are still insufficient in terms of storage stability and thermal coloring properties when viewed from a practical standpoint. for example,
In Japanese Patent Publication No. 39-18704, a coupler made of discontinuous particles is shown, but in this case, the diazo compound is a double salt of zinc chloride, which easily absorbs moisture, making it difficult to manufacture. However, it has the disadvantage that it cannot maintain long-term shelf life due to the influence of moisture during product storage. Also, special public service 49-42922
No. 1 also shows a type in which the coupler is made of discontinuous particles, but this type also has poor storage stability for the same reason as mentioned above. Furthermore, these conventional techniques do not disclose any technology that harmonizes the storage stability and heat-sensitive coloring properties of products. Recently, there has been a strong demand for heat-sensitive recording materials to have high-speed recording properties so that they can be used as output recording materials for facsimile, telex, electronic computers, medical measuring instruments, and the like. In particular, in the field of facsimile, there is a need for thermal recording that is compatible with high-speed printing in order to reduce the cost of information transmission. Although diazo-based heat-sensitive recording materials have the advantage of being fixable, they have the disadvantage of insufficient thermal responsiveness to a thermal head when applied to such uses. The present inventors have overcome the above-mentioned drawbacks of conventionally proposed diazo-based heat-sensitive recording materials, and have created a diazo-based heat-sensitive recording material having a single-layer heat-sensitive recording layer that is easy to manufacture, and which has sufficient thermal responsiveness to a thermal head. As a result of intensive research to develop a product with excellent long-term storage stability, the present invention was completed. That is, according to the present invention, the following general formula (),
The main components are at least one diazo compound selected from water-insoluble diazo compounds represented by () and () and phloroglucin as a coupler, and these diazo compounds exist as discontinuous particles, and phloroglucin A diazo-based heat-sensitive recording material is provided, which is characterized in that a heat-sensitive coloring layer existing as continuous particles is provided on a support. (However, in the general formulas (), () and (), R ₁ , R ₆ , R ₈ are hydrogen, C ₁ to C ₅ alkyl groups or alkoxyl groups, R ₂ , R ₃ .R ₉ are hydrogen, _C1 ～ _C5
R ₄ and R ₅ are the same or different alkyl groups or hydroxyalkyl groups, R ₇ is hydrogen, halogen, C ₁ to _{C 5} alkyl group or alkoxy group, R ₁₀ is

【formula】 【formula】

【formula】

[Formula] or

In the formula, R ₁₁ represents hydrogen, a C _1-5 alkyl group, an alkoxyl group, or a halogen, and M ₁ , M ₂ and M ₃ each represent an anion of a fluorine-containing inorganic acid. ) The water-insoluble diazo compound used in the present invention is represented by the following general formula. (However, in the general formulas (), () and (), R ₁ , R ₆ and R ₈ are hydrogen, C ₁ to _{C 5} alkyl groups or alkoxyl groups, R ₂ , R ₃ and R ₉ are hydrogen, _C1 ～
C ₅ alkyl group or alkoxyl group or halogen, R ₄ and R ₅ are the same or different C ₁ to _{C 5}
an alkyl group or a hydroxylalkyl group,
R ₇ is hydrogen, halogen, C ₁ to C ₅ alkyl group or alkoxyl group, R ₁₀ is

【formula】 【formula】

【formula】

[Formula] or

[Formula], R ₁₁ is hydrogen, C _1-5 alkyl group or alkoxyl group, or halogen, M ₁ , M ₂ and M ₃ are anions of fluorine-containing inorganic acids (BF ₄ , PF ₆ etc.) are represented respectively. ) Specific examples of those corresponding to general formula () include the following. Specific examples of those corresponding to general formula () include the following. Specific examples of those corresponding to general formula () include the following. In the case of the present invention, it is necessary to use phloroglucin as the coupler contained in the heat-sensitive coloring layer. In order to achieve the intended purpose of the present invention, a combination of the specific water-insoluble diazo compound and phloroglucin is employed as a heat-sensitive coloring component, and the specific water-insoluble diazo compound is not included in the heat-sensitive coloring layer. It is necessary for the phloroglucin to be present as continuous particles and for the phloroglucin to be present as continuous particles. With such a configuration, it is possible to obtain a diazo-based heat-sensitive recording material which is significantly improved in thermal response to a thermal head and also has significantly excellent long-term storage stability. In addition, in the present invention, "discontinuous particles" with respect to the specific water-insoluble diazo compound means that the specific water-insoluble diazo compound is
It is obtained when layer formation is performed using a dispersion in which insoluble solid particles are dispersed in a solvent. Refers to the state of existence of a water-insoluble diazo compound in a layer. Also,
What is a “continuous particle” when it comes to phloroglucin?
This refers to the state in which phloroglucin exists in a layer, which is obtained when layer formation is performed using a solution in which phloroglucin is dissolved in a solvent. In the present invention, it is preferable to further add a thermofusible substance to the thermosensitive coloring layer in order to allow the coloring reaction to proceed smoothly (instantaneously) during heating and to enable high-speed coloring. Specific examples of such things include, for example, the following: In the present invention, those having a melting point or softening point in the range of 50 to 250°C are used. Alcohol derivatives such as 2-tribromoethanol, 2,2-dimethyltrimethylene glycol, and 1,2-cyclohexanediol, acid derivatives such as malonic acid, glutaric acid, maleic acid, and methylmaleic acid, and animals such as beeswax and Serratus wax. plant waxes such as carnauba wax,
Mineral waxes such as Montan wax, petroleum waxes such as paraffin wax and microcrystalline wax, and other synthetic waxes such as polyhydric alcohol esters of higher fatty acids, higher amines, higher amides, condensates of fatty acids and amines, and fragrances. condensates of group and amines, synthetic paraffin, chlorinated paraffin, metal salts of higher fatty acids, etc. In the present invention, these thermofusible substances are used in an amount of 2 to 30 parts by weight, preferably 5 to 10 parts by weight, per 1 part by weight of the diazo compound. If this amount is less than the above range, the effect of improving color development will be reduced. In the case of the present invention, it is particularly preferable to use 5 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 undesirable. In the present invention, a binder is used to bind each component in the layer to each other and to stably support this layer on a support. Regarding this binder, in the case of the present invention, it is preferable to use one that melts or softens at a temperature of 50 to 250°C. When such a heat-melting or heat-softening substance is used as a binder, the binder melts or softens during heating and coloring, making it possible to obtain a product with even higher heat-coloring properties. Examples of such thermofusible or thermosoftening binders include the following. Polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polystyrene, polyester, styrene/butadiene/acrylic copolymer, polyacrylic ester, polyacrylamide, polymethacrylic ester, polybutadiene, etc. In addition, in the case of the present invention, such a thermofusible or thermosoftening binder does not necessarily have to be used alone, but rather binds each component in the layer firmly to the support, and also within the range that does not particularly impede the purpose;
A heat-resistant binder can also be used in combination, usually in a proportion not exceeding 30% by weight. Examples of such binders include those shown below. Of course, depending on the case, a heat-refractory substance can be used alone. polyvinyl alcohol, polyacrylamide,
casein, gelatin, starch and its derivatives,
Polyvinylpyrrolidone, carboxymethylcellulose, methylcellulose, ethylcellulose, chlorinated rubber, polystyrene (MW: 100,000 or more), polyurethane, urea-formalin resin, phenolic resin, etc. Water-soluble, organic solvent-soluble, water-based dispersion resin, etc. Further, in the present invention, the heat-sensitive coloring layer may contain acidic substances, basic substances, fillers, and other substances as auxiliary components, if necessary. Acidic substance: Acidic substances are added as necessary to prevent coupling reactions and to maintain storage stability, and include, for example, the following. Tartaric acid, citric acid, boric acid, lactic acid, gluconic acid, sulfuric acid, etc. Basic substance: A basic substance is added as necessary to further promote the coupling reaction during heating.
Examples include: Caustic alkalis and alkali carbonates such as sodium hydroxide, calcium hydroxide, potassium carbonate, etc.
Substances that generate basicity when heated include urea,
Thiourea and derivatives thereof, alkali salts of trichloroacetic acid, ammonium chloride, ammonium sulfate, ammonium citrate, etc. Filler: When heating with a thermal head or the like, a filler is added to improve the matching property to the thermal head, and examples of such fillers include the following. Organic and inorganic solid particles such as styrene resin particles, urea-formalin condensate resin particles, aluminum hydroxide, magnesium hydroxide, calcium carbonate, titanium, talc, kaolin, silica, and alumina. Other auxiliary ingredients used include zinc chloride, zinc sulfate, sodium citrate, guanidine sulfate, calcium gluconate, sorbitol, and sugar rose to inhibit or assist color development. To obtain the heat-sensitive recording material according to the present invention, a layer-forming coating solution is prepared by dissolving or dispersing the layer-forming components described above in a suitable solvent, and this coating solution is applied to paper, synthetic paper, plastic film, metal laminate, etc. Solid content is 1 to 10 on a suitable support such as
Coat and ^dry to obtain a product.
In this case, the solvent for dissolving or dispersing the layer-forming components is usually water or an aqueous medium in which an organic solvent is dissolved in water. Next, the present invention will be explained in more detail with reference to Examples. Example 1

【table】

[Table] Dissolve the above composition, then add 4 parts by weight of polyvinyl acetate emulsion (solid content 50%),
Prepare the liquid. Photosensitive liquid C was prepared by mixing 50 parts by weight of the above dispersion A and 50 parts by weight of liquid B. Spread this liquid C on high-quality paper (approx.
g/m ² ) and dried, the adhesion amount was 1.5
A photosensitive layer of g/m ² (solid content) was provided and further calendered to obtain a heat-sensitive recording material with a Beck smoothness of 300 seconds. This heat-sensitive recording material is transferred to a heat-sensitive facsimile machine [OKIFAX-7100 manufactured by Oki Electric Industry Co., Ltd.].
It was printed and recorded using. The entire surface of the printed image was exposed using the exposure section of a Ricopy High Start Model 4 (manufactured by Ricoh Co., Ltd.). In this way, a clear blue-purple print record with good contrast was obtained. This image was fixed without recoloring due to heat or decoloring of the image due to organic solvents. Example 2

【table】

[Table] After the above composition was pulverized and dispersed for 24 hours using a ball mill, 5 parts by weight of polyvinyl acetate emulsion (solid content 50%) was added and thoroughly stirred to prepare a coupler solution E. Mix 50 parts by weight of the above liquid D and 50 parts by weight of liquid E,
Photosensitive solution F was prepared. Spread this F solution on high-quality paper (approx.
g/m ² ) and dried, the amount of adhesion was 2.0 g/m 2 ).
A photosensitive layer of m ² (solid content) was provided and further calendered to obtain a heat-sensitive recording material with a Beck smoothness of 400 seconds. Example 3

[Table] Coating liquid G was prepared by pulverizing and dispersing the above composition for 24 hours using a ball mill. This G liquid was used in Example 2.
A heat-sensitive recording material was obtained by coating it on a support in the same manner as above. Example 4

[Table] Benzene

[Table] Coating solution H was prepared by pulverizing and dispersing the above composition for 24 hours using a ball mill, and this was coated on a support in the same manner as in Example 3 to obtain a heat-sensitive recording material. Example 5

[Table] A heat-sensitive recording material was obtained using the above composition in the same manner as in Example 3. Next, the heat-sensitive recording materials obtained in Examples 2 to 5 were printed and exposed in the same manner as in Example 1 to obtain completely fixed colored products. In addition, Table 1 shows the results of the preservability and color development tests for these products. For comparison, in Example 1, water-soluble ZnCl ₂ was used instead of the water-insoluble diazo compound.
In a product obtained in the same manner except for using a double salt (Comparative Example 1) and Example 2, as a coupler,
Regarding the product obtained in the same manner (Comparative Example 2) except that resorcin was used instead of phloroglucin,
The storage stability and color development were tested. The results are also shown in Table-1. In Table 1, the shelf life test is a forced deterioration test in which the exposed product is used as a test product and left for 24 hours at 40°C and 90% relative humidity. After the test, the skin density of the test product before and after the test was measured using a Macbeth densitometer (RD-514), and the test results were evaluated. In this case, if the skin density value after the test is 0.25 or less, it means that the product has a shelf life of one year or more when stored in a dark place at room temperature and humidity. Further, the color development test shows the print density (densitometer: RD-514) obtained by solid printing in G mode using Rifax 303 (manufactured by Ricoh Co., Ltd.).

[Table] * Color development immediately after application As is clear from Table 1, the product of the present invention has excellent both preservability and color development. Also,
When the product of the present invention is copied using a transparent original using a heat-developable diazo copying machine (Recopy Hydry Model 4, manufactured by Ricoh Co., Ltd.), it is possible to obtain high-density and clear copies that are faithful to the original. did it.

Claims (1)

[Scope of Claims] 1 At least one diazo compound selected from water-insoluble diazo compounds represented by the following general formulas (), (), and (), and phloroglucin as a coupler thereof, as main components, and 1. A diazo-based heat-sensitive recording material, comprising a heat-sensitive coloring layer on a support, in which the diazo compound exists as discontinuous particles, and the phloroglucin exists as continuous particles. (However, in the general formulas (), () and (), R ₁ , R ₆ and R ₈ are hydrogen, C ₁ to _{C 5} alkyl groups or alkoxyl groups, R ₂ , R ₃ and R ₉ are hydrogen, _C1 ～
C ₅ is an alkyl group, alkoxyl group or halogen, R ₄ and R ₅ are the same or different alkyl group or hydroxyalkyl group, R ₇ is hydrogen,
Halogen, C ₁ to C ₅ alkyl group or alkoxy group, R ₁₀ is [Formula] [Formula] [Formula] [Formula] or [Formula], R ₁₁ is hydrogen, C _{1 to 5} alkyl group, or An alkoxyl group or a halogen, and M ₁ , M ₂ and M ₃ each represent an anion of a fluorine-containing inorganic acid. )