JPH0225351B2 - - 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 the reaction between an organic metal salt and a ring agent, and those that produce heat-sensitive coloring by using the reaction between a leuco dye and an oxidizing substance. It is being 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 heating printing after once recording by heating 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 information for securities, gift certificates, admission tickets, certificates, slips, etc. Furthermore, in the case of such recording materials, when exposed to an environment of 70° C. or higher, the entire surface develops color, which causes the problem that the recording becomes illegible. 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-sensitive 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 is provided with 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 made into discontinuous particles. The color reaction is prevented from proceeding by separating it from the other components. However, all of the conventional ones are still insufficient in terms of storage stability and heat coloring properties when viewed from a practical standpoint. For example, storage stability is still insufficient. For example, in order to obtain a product with a high shelf life, it has been proposed to form diazo compounds and couplers into discontinuous particles. Furthermore, it is still not satisfactory in terms of color development, and images with high color development cannot be obtained by instantaneous heating. 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, when applied to such uses, conventional ones have the disadvantage of insufficient thermal responsiveness to a thermal head. . 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 shelf life, we have completed the present invention. That is, according to the present invention, the following general formula (),
At least one diazo compound selected from the diazo compounds represented by () and ();
Provided is a diazo-based heat-sensitive recording material, characterized in that a heat-sensitive coloring layer is provided on a support, the main component being phloroglucin as a coupler, and the diazo compound and phloroglucin both exist as discontinuous particles. be done. (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 ～
_C5 alkyl group or alkoxyl group or halogen, _R4 and _R5 are the same or different alkyl group or hydroxyalkyl group, _R7 is hydrogen,
Halogen, C ₁ to C ₅ alkyl group or alkoxy group, R ₁₀ is

【formula】

[Formula] or

[Formula], M ₁ , M ₂ and M ₃ each represent an anion of a fluorine-containing inorganic acid. ) is provided. In the present invention, in order to achieve the intended purpose, the diazo compound to be contained in the heat-sensitive coloring layer includes at least one of the water-insoluble compounds represented by the above general formulas () to () and its It is necessary to select phloroglucin as the coupler and to make all of these reactive components exist as discontinuous particles in the heat-sensitive coloring layer. With this structure, it has higher color development (high-speed recording performance) than conventional diazo-based heat-sensitive recording materials, can develop color by instantaneous heating, and has significantly superior long-term storage properties. Recording materials can be obtained. When using a water-soluble diazo compound (for example, ZnCl ₂ double salt, etc.),
This material is easily affected by moisture in the air,
It is insufficient in terms of long-term shelf life and does not give satisfactory results. On the other hand, in the case of the present invention, since the above-mentioned specific water-insoluble diazo compound is used, there is no such difficulty. Furthermore, in the case of the present invention, since the diazo compound is water-insoluble, coupling reactions in the manufacturing process are prevented, and a product with high background whiteness can be easily obtained. In the present invention, the term "discontinuous particles" with respect to the specific water-insoluble diazo compound and phloroglucin refers to a dispersion in which the specific water-insoluble diazo compound or phloroglucin is dispersed as insoluble solid particles in a solvent during layer formation. Refers to the state of existence of a water-insoluble diazo compound or phloroglucin in a layer obtained when layer formation is performed using a liquid. 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 hydroxyalkyl group of R ₇
is hydrogen, halogen, C ₁ to C ₅ alkyl group or alkoxyl group, R ₁₀ is

【formula】

[Formula] or

[Formula], M ₁ , M ₂ and M ₃ each represent an anion (BF ₄ , PF ₆ etc.) of a fluorine-containing inorganic acid. ) 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 items that fall under the set () are:
For example, the following can be mentioned: In the present invention, it is preferable to further add a thermofusible substance to the thermosensitive coloring layer in order to make the coloring reaction proceed more smoothly (instantly) during heating and to enable high-speed coloring. Specific examples of such things include, for example, the following: In the present invention, the melting point or softening point is 50 to
A temperature range of 250℃ is adopted. Alcohol derivatives such as 2-tribromoethanol, 2,2-dimethyltrimethylene glycol, and 1,2-cyclohexanediol, acid derivatives such as malonic acid, glutanic 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. As this binder, for example, organic solvent-soluble or organic solvent-dispersible resins such as cyclized rubber, vinyl polymers or copolymers, cellulose derivatives, and hydrocarbon resins are used. 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, and examples thereof include the following. Caustic alkalis and alkali carbonates such as sodium hydroxide, camsium hydroxide, and potassium carbonate. As a substance that generates basicity when heated,
Urea, thiourea and their derivatives, alkali salts of trichloroacetic acid, ammonium chloride, ammonium sulfate, ammonium citrate, etc. Filler: A filler is added to improve the matching property to a thermal head when heating is performed 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, talcum 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, the above-mentioned layer-forming components are dissolved or dispersed in a suitable solvent (this solvent shows no solubility for both the diazo compound and phloroglucin), and layer-forming coating is performed. Prepare a liquid, apply this coating liquid onto a suitable support such as paper, synthetic paper, plastic film, metal laminate, etc. to a solid content of 1 to 10 g/m ² and dry. shall be. In this case, any solvent that does not dissolve both the water-insoluble diazo compound and phloroglucin can be used as a solvent for dissolving or dispersing the layer-forming component. Examples of such solvents include n-hexane, cyclohexane, n-hebutane, ligroin, petroleum ether,
Examples include petroleum solvents such as benzene. Next, the present invention will be explained in more detail with reference to Examples. Example 1 (1) Diazo dispersion liquid

【table】

[Table] (2) Katsupular dispersion <Liquid C> Phloroglucin 5 parts by weight N-octadecyl (4-methoxycarbonyl)
Benzamide 5 Cyclized rubber 10 N-hexane 30 <Liquid D> Phloroglucin 5 parts by weight Clay 15 Urea 5 Polystyrene (≒800, difficulty point≒80℃)
10 〃 Benzene 15 〃 (3) Mixed dispersion liquid

【table】

【table】

[Table] Each solution was prepared by pulverizing and dispersing each of the compositions shown above using a ball mill for 24 hours. Next, the following coating liquids were prepared using these liquids. Example 1: <Liquid A> + <Liquid C> Example 2: <Liquid B> + <Liquid D> Example 3: <Liquid E> Example 4: <Liquid F> Comparative example 1: In Example 1 Comparative Example 2: In Example 2, the diazo compound in <Liquid B> was replaced with toluene as the solvent of <Liquid A> (that is, the diazo compound component is somewhat dissolved). _1/2 ZnCl ₂ ). Comparative Example 3: Example 3 except that the coupler of <Liquid E> was resorcinol. Comparative Example 4: In Example 4, the diazo compound of <Liquid F> was made into a water-soluble salt (Cl _1/2 SnCl ₂ ). Next, apply the coating solution obtained above on high-quality paper (approximately 50 g/
A heat-sensitive coloring layer was coated on the surface of 10g/ ^m2 (coating liquid amount), dried, and calendered to obtain a heat-sensitive recording material with a Bekk smoothness of 500 ^seconds . . The heat-sensitive recording material obtained in this way was
After printing in G-mode using a printer (manufactured by Ricoh Co., Ltd.), it was completely exposed and fixed using Ricopy High Start 205 (manufactured by Ricoh Co., Ltd.). The print density of the printed (colored) product obtained as described above was measured using a Macbeth densitometer (RD-514). The results are shown in Table-1. Table 1 also shows the results of the skin density change test over time and the preservability test. In addition, in terms of skin density, the initial skin density refers to the amount that is applied to paper immediately after preparing the coating solution, dried,
This is the value obtained by completely exposing the fully exposed surface using a Macbeth densitometer. On the other hand, the skin density over time is the value obtained by measuring the surface density of the fully exposed surface with a Macbeth densitometer.
After leaving it for 24 hours, it was applied on paper, dried, completely exposed, and the fully exposed surface was measured using a Macbeth densitometer. In addition, storage stability was determined by coating the sample on paper immediately after preparing the coating solution, drying it, leaving it in a dark place at 40°C and 90% relative humidity for 24 hours, fully exposing it to light, and measuring the exposed surface with a Macbeth densitometer. Evaluation was made using the values measured. In this case, if the measured value is less than or equal to 0.20,
Indicates that it has a shelf life of 2 years or more when stored at room temperature and humidity in a dark place.

【table】

Claims (1)

[Scope of Claims] 1. At least one diazo compound selected from the following general formulas (), (), and ():
A diazo which is characterized in that a heat-sensitive coloring layer is provided on a support, the main components being a seed diazo compound and phloroglucin as a coupler thereof, and in which both the diazo compound and phloroglucin exist as discontinuous particles. thermosensitive recording material. (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 ～
_C5 alkyl group or alkoxyl group or halogen, _R4 and _R5 are the same or different alkyl group or hydroxyalkyl group, _R7 is hydrogen,
Halogen, C ₁ - C ₅ alkyl group or alkoxy group, R ₁₀ represents [Formula] [Formula] or [Formula], M ₁ , M ₂ and M ₃ each represent an anion of a fluorine-containing inorganic acid . )