JPH0231674B2 - - Google Patents

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 fixed with light. That is, the present invention provides a diazo-based heat-sensitive 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 irradiated with light, and does not recolor when heat is applied again. It is related to. In addition to being used as copy paper for books and documents, thermosensitive recording materials are also used as output recording paper for electronic computers, facsimile machines, medical measuring machines, etc., as well as thermal recording magnetic ticket paper and thermal recording label paper. be done. 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 able to provide sufficient thermal responsiveness to a thermal head in terms of long-term storage stability. In particular, in fields such as facsimile, high-speed recording performance (high-speed color development) is strongly required to reduce information transmission costs, but conventional diazo-based products
These requirements have not yet been fully satisfied. The present inventors discovered that, unlike conventional diazo thermosensitive recording materials, it has sufficient thermal responsiveness to a thermal head.
As a result of intensive research to develop a diazo thermosensitive recording material that has high color density and excellent head matching properties (head abrasion, head scum, staking, etc.), the present invention has been completed. That is, according to the present invention, in a device in which a heat-sensitive coloring layer containing a diazo compound, a coupler, a heat-fusible substance, and a heat-fusible or heat-softening binder is provided on a support, the heat-sensitive coloring layer and the support
A diazo thermosensitive recording material, characterized in that a layer containing a filler having an oil absorption of 100 ml/100 g or more based on JISK 5101 is provided, and a layer containing a filler having a Mohs hardness of 3 or less is provided on the thermosensitive coloring layer. Materials provided. Conventionally, in diazo photosensitive paper, it is known that a layer containing silica and a binder is provided on a support, and a photosensitive layer containing a diazo compound and a coupler is provided thereon. However, unlike such conventional techniques, the present invention uses a diazo compound as a thermosensitive coloring layer so that a colored image can be obtained with sufficient thermal responsiveness even with a small amount of thermal energy from a thermal head, thermal pen, etc. In addition to the basic reaction components of Kupler, a material containing a heat-fusible substance and a heat-fusible or heat-softening binder is used, and this heat-sensitive coloring layer has sufficient color density and long-term storage stability. Therefore, between the heat-sensitive coloring layer and the support, JISK
A layer containing a filler with an oil absorption of 100 ml/100 g or more based on 5101 is provided, and a layer containing a filler with a Mohs hardness of 3 or less is provided on the upper surface of the heat-sensitive coloring layer in order to improve the head matching property. be.
The oil absorption amount is 100ml/
When a layer containing 100 g or more of filler is interposed as a precoat layer, not only is storage stability deterioration due to moisture absorption from the back side of the support of the heat-sensitive coloring layer prevented, but also the support of the melted thermofusible material during heated printing is prevented. In addition, since the heat-sensitive coloring layer is formed on a precoat layer with a rough surface containing fillers, its surface area is enlarged, and even if the decomposition rate of the diazo compound is the same at the same exposure dose, , the amount of the diazo compound used can be increased, and as a result, improvements in fixing properties and color density can be achieved. In addition, by providing a layer containing a filler having a Mohs hardness of 3 or less on the heat-sensitive coloring layer, it is possible to prevent the thermofusible substance in the heat-sensitive coloring layer from sticking to the heat head (sticking). It is possible to effectively reduce debris adhesion to the thermal head and wear of the thermal head. In the present invention, the filler contained in the precoat layer provided between the heat-sensitive coloring layer and the support is
Oil absorption amount based on JISK 5101 is 100ml/100g or more,
Preferably, it is an inorganic or organic substance in the range of 150 to 400 ml/100 g, and examples of such substances include the following. Note that the numbers shown in brackets after the substance names shown below represent the oil absorption amount. Diatomaceous earth (100-160), anhydrous aluminum oxide (100-250), titanium oxide (100-120), magnesium carbonate (100-150), silica (100-800), magnesium aluminosilicate (300-400), zeolite (100-1000), urea-formalin resin fine particles (100-500). In the present invention, these oil absorption amounts are 100ml/100g.
The above-mentioned fillers should be added in an amount of 10 to 10 to 300% by weight, preferably 50-200% by weight
It is desirable to use it within the range of . This addition amount is 10
If the amount is less than 300% by weight, the effect of adding it will not be sufficient, while if it exceeds 300% by weight, the color tone will become pale, the support will become stiff, the suppleness will fade, and the naturalness of the support will deteriorate. The feeling is lost. In the present invention, the filler to be contained in the coating layer (overcoat layer) provided on the surface of the heat-sensitive coloring layer has a Mohs hardness of 3 or less, and examples of such filler include the following: Can be mentioned. Note that the number shown in brackets after the substance name indicates Mohs hardness. Aluminum hydroxide (3), dolomite (3-4),
Calcium carbonate (3-4), gypsum (2), calcium hydroxide (2-3), barium sulfate (3-3.5),
Kaolin (1-2.5), talc (1-1.5), birofilite (1-2), aluminum silicate (1
~2.5), magnesium silicate (1 to 2.5), calcium silicate (1 to 2.5), urea-formalin resin fine particles (1 or less), polystyrene resin fine particles (1 or less). In the present invention, these fillers having a Mohs hardness of 3 or less are applied in an amount of 5 to 200% by weight, preferably 10 to 100% by weight, based on the total solid content in the heat-sensitive coloring layer, in order to improve head matching properties. Ru. If the amount of this filler used is less than 5% by weight, the effect of preventing scum adhesion and staking will not be sufficient, and if it exceeds 200% by weight, thermal conductivity will deteriorate.
Color development becomes unsatisfactory. Furthermore, if the Mohs' hardness exceeds 3, the wear of the head will be too great, making it unusable for practical use. In addition, the heat-sensitive color forming layer as used in the present invention refers to one layer or a multilayer of two or more layers formed to support heat-sensitive color forming layer forming components such as a diazo compound, a coupler, and a thermofusible substance on a support. This means the entire coating layer. Therefore, the components for forming the thermosensitive coloring layer may be contained simultaneously in one coating layer, or appropriately separated and contained in two or more multilayer coating layers. As the diazo compound and coupler used in the present invention, those commonly used for diazo photosensitive paper are applicable, and examples thereof include those shown below. Diazo compound: As the diazo compound used in the present invention,
A commonly used one, for example, one represented by the following general formula can be used. However, in the general formulas [], [] and [], R ₁ , R ₆ and R ₈ are hydrogen, halogen, C ₁ to _{C 5} alkyl group or alkoxyl group, or

[Formula] or

[Formula] (R ₁₁ , R ₁₂ : Same as R ₂ ), R ₂ , R ₃ , R ₄ are hydrogen, halogen, C ₁ to C ₅ alkyl group or alkoxy group, R ₄ and R ₅ are the same or different _C1 - _C5 alkyl group, hydroxyalkyl group, or

[Formula] (R ₁₃ : hydrogen, C ₁ to C ₃ alkyl group or alkoxyl group, or halogen), R ₇ is hydrogen, halogen, trifluoromethyl group, C ₁ to _{C 5} alkyl group or alkoxyl group, or ,

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (R ₁₄ , R ₁₅ , R ₁₆ : Same as R ₁₃ ), M ₁ , M ₂ and M ₃ are acid residues or acid residues forming a double salt with a metal salt. In this case, the acid residue is preferably a halogen ion or a fluorine-containing inorganic acid ion such as BF ₄ ^- or PF ₆ ^- , while the metal salt that forms a double salt with the acid residue is For example, _ZnCl2 , _CdCl2 ,
Examples include _SnCl2 . Specific examples of those falling under the general formula [] include the following. Specific examples of those falling under the general formula [] include the following. Specific examples of those falling under the general formula [] include the following. In the present invention, in order to obtain a product with further improved long-term shelf life, HBF ₄ is used as the diazo compound.
Advantageously, it is used in the form of a water-insoluble salt such as a fluorine-containing salt such as or HPF ₆ . Couplers: Couplers used in the present invention include phenol, resorcin, methylresorcin, 4,4-bisresorcin, phloroglucin, resorcinic acid,
Phloroglucic acid, 2-ethyl-5-methoxy-
1,3-dihydroxybenzene, 5-methoxy-
1,3-dihydroxybenzene, 4-N,N-dimethylphenol, 2,6-dimethyl-1,3,
5-trihydroxybenzene, 2,6-dihydroxybenzoic acid, 2,6-dihydroxy-3,5-
Phenol derivatives such as dibromo-4-methoxybenzoic acid, α-naphthol, β-naphthol, 4
-methoxy-1-naphthol, 2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene-6-sulfonic acid sodium, 2-hydroxy-3
Examples include naphthol derivatives such as -propylmorpholinonaphthoic acid, 2-hydroxy-3-naphtho-0-toluidide, and 2-hydroxy-3-naphthoic acid morpholinopropylamide, but are of course not limited to these. However, any substance that can act as a coupler for the diazo compound can be applied. In the present invention, thermofusible or thermosoftening substances are preferably used in order 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, and 1,2-cyclohexanediol, acid derivatives such as malonic acid, glutaric acid, maleic acid, and methylmaleic acid, and animals such as beeswax and selaz wax. waxes, vegetable 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, condensates of aromatics and amines, synthetic paraffins, chlorinated paraffins, metal salts of higher fatty acids, higher linear glycols, 3,4
-Dialkyl epoxyhexahydrophthalate, etc. The thermofusible substance used in the present invention preferably has a melting point or softening point in the range of 50 to 250°C. If the melting point or softening point is less than 50°C, the shelf life of the product tends to decrease, and if it exceeds 250°C, the thermal response of the product to a heat head becomes unsatisfactory. In addition, from the viewpoint of obtaining a product with high-speed coloring property (high-speed recording property), the thermofusible or heat-softening substance used in the present invention is preferably 2 to 30 parts by weight, based on 1 part by weight of the diazo compound. It is used in a proportion of 5 to 10 parts by weight. If this amount is less than the above range, the color development will be insufficient,
The resulting product is unsuitable as a recording material for high-speed recording. 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. Therefore, in the case of the present invention, the amount of the thermofusible or thermosoftening substance added is preferably kept within the above range. In the present invention, a heat-fusible or heat-softening binder is used in order to firmly support the heat-sensitive coloring layer on the support, but such binders include:
Examples include polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyacrylic acid ester, polystyrene, polybutadiene, polyacrylamide, styrene/butadiene/acrylic copolymer, petroleum resin, and the like. These binders preferably have a melting point or softening point in the range of 50 to 250°C. 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: 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 cause a coupling reaction during heating, and examples thereof include the following. Caustic alkalis and alkali carbonates such as sodium hydroxide, calcium hydroxide, potassium carbonate, etc. Substances that generate basicity when heated include urea, thiourea and their derivatives, alkali salts of trichloroacetic acid, ammonium chloride, ammonium sulfate,
such as ammonium citrate. Filler: A filler is added to improve the matching property to a thermal head when heated by a 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 include zinc chloride, zinc sulfate, sodium citrate, guanidine sulfate, calcium gluconate,
Sorbitol, satsuka rose, etc. are used. In the present invention, as the binder, thermofusible or thermosoftening binders as described above are preferably used, but these binders do not necessarily need to be used alone, and each component in the layer is Usually 30% by weight of other binders are added to firmly bind to the support.
Can be used together at a ratio of less than Examples of such binders include the following. polyvinyl alcohol, polyacrylamide,
casein, gelatin, starch and its derivatives,
Polyvinylpyrrolidone, carboxymethylcellulose, methylcellulose, ethylcellulose, polyester (≒100,000 or more), polystyrene (≒100,000 or more), chlorinated rubber, styrene-maleic anhydride copolymer, iso(or diiso)butylene-maleic anhydride copolymer Water-soluble urea-formalin resin, phenol resin, melamine resin, etc.
Organic solvent soluble or aqueous dispersion resin. In the present invention, the binder for the precoat layer and overcoat layer is not particularly limited, and any of the binders described above can be applied. In order to produce the diazo-based heat-sensitive recording material of the present invention, the above-mentioned diazo compound, coupler, heat-fusible substance, heat-fusible or heat-softening binder, and other materials may be used as necessary on the support. auxiliary ingredients,
A heat-sensitive coloring coating solution is prepared by dissolving or dispersing it in water, an aqueous solvent prepared by dissolving an organic solvent in water, toluene, methyl isobutyl ketone, methyl cellosolve, n-hexane, cyclohexane, ligroin, etc. Oil absorption amount formed in advance on a support such as synthetic paper or plastic film
It is coated on a precoat layer containing a filler of 100ml/100g or more and dried, and an overcoat layer containing a filler with a Mohs hardness of 3 or less is further provided on the heat-sensitive coloring layer. The solid content of the coating solution on the support should be in the range of 1 to 10 g/m ² for the precoat layer, 1 to 10 g/m ² for the thermosensitive coloring layer, and 0.5 to 5 g/m ² for the overcoat layer. It is better. The heat-sensitive recording material of the present invention can be advantageously applied in various heat-sensitive recording fields, particularly as output recording paper for facsimile machines and electronic computers that require high-speed recording. The recorded characters and images can be fixed by decomposing the unreacted diazo compound by the image formation after-light by heating. Furthermore, the heat-sensitive recording material of the present invention can be applied to recording necessary information on securities, gift certificates, admission tickets, certificates, slips, etc., and for creating them, by taking advantage of its fixing properties. Next, the present invention will be explained in more detail with reference to Examples. Example Solution A: Silica fine particles 10 parts by weight Polyvinyl acetate emulsion (solid content 50%)
10 〃 Water 80 〃 The above composition was mixed and stirred to prepare a dispersion liquid A. Solution B: Urea-formalin resin fine particles 10 parts by weight polyvinyl alcohol (10% aqueous solution)
20 〃 Polyacrylic acid ester emulsion (solid content 45%) 6 parts by weight water 64 〃 The above composition was mixed and stirred to prepare dispersion liquid B. Liquid C: Urea-formalin resin fine particles 5 parts by weight Chlorinated rubber 5 Toluene 90 The above compositions were mixed and stirred to prepare a dispersion liquid C. Solution D: Kaolin 5 parts by weight Isobutylene-maleic anhydride copolymer (30
% aqueous solution) 20 〃 Water 75 〃 The above composition was mixed and stirred to prepare Dispersion Liquid D.

[Table] After dispersing the above composition for 12 hours using a ball mill, polyvinyl acetate emulsion (solid content 50
%) was added thereto, and the mixture was mixed and stirred until the mixture became uniform, thereby preparing a dispersion liquid E.

[Table] Dispersion liquid F was prepared by dispersing the above composition for 24 hours using a ball mill. Liquid G: Phloroglucin 5 parts by weight High grade linear glycol (Product name: AOG-YO8
[Manufactured by Daicel Corporation] 2 Calcium carbonate 1 Polyester resin (≒1000) 2 N-hexane 90 The above composition was dispersed for 24 hours using a ball mill to prepare dispersion liquid G. . Table 1 shows solutions A to G prepared as described above.
Apply each solution on high-quality paper (50g/m ² ) using a combination of
After drying, a heat-sensitive recording material with a Beck smoothness of 400 seconds was prepared by further calendering (the amount of each liquid adhered was 1.0 to 5.0 g/m ² (solid content)). Comparative Example Solution H: A dispersion solution H was prepared in the same manner as in Example except that kaolin in Solution D was replaced with titanium oxide (Mohs hardness: 6).

[Table] Using the heat-sensitive recording material obtained as described above as a sample, G
After printing in - mode, it was completely exposed and fixed using Ricopy High Start Type 4 (manufactured by Ricoh Co., Ltd.). These materials did not develop color even when heated, and the images did not disappear when exposed to organic solvents. Next, the heat-sensitive recording material obtained above was subjected to a color density test, a staking test, and a preservability test. The results are shown in Table-2. In addition, the color density is the solid print density in the G-mode of Refux 303 using a Macbeth densitometer (RD-
514). The statesking property was also determined visually using the RIFAX 303 in G-mode to determine the state of occurrence in solid printing. Preservability was also determined by a forced deterioration test in which the sample was left in a dark place at a temperature of 40°C and humidity of 90% RH for 24 hours, and the skin concentration before and after the test was measured. In this case, a Macbeth densitometer was used for density measurement both before and after the test and after exposure. It has been confirmed that if the surface density value is 0.20 or less, it is a heat-sensitive recording material that has a shelf life of 2 years or more when stored in a dark place at room temperature and humidity.

[Table] From the results shown in Table 2, all of the products of the present invention had satisfactory quality in terms of color density, storage stability, and head matching properties.

Claims (1)

[Claims] 1. A heat-sensitive color forming layer containing a diazo compound, a coupler, a heat-fusible substance, and a heat-fusible or heat-softening binder is provided on a support, and there is no space between the heat-sensitive color forming layer and the support. A layer containing a filler with an oil absorption of 100ml/100g or more based on JISK 5101 is provided,
A diazo-based heat-sensitive recording material, further comprising a layer containing a filler having a Mohs hardness of 3 or less on the heat-sensitive coloring layer.