JPS6342593B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-developable heat-sensitive recording material having an improved heat-sensitive layer. More specifically, the present invention relates to a water-developable heat-sensitive recording material having a heat-sensitive layer that is highly sensitive, has excellent oil resistance and chemical resistance, and is capable of producing images with strong film strength. Unlike silver halide photographic materials, heat-sensitive recording materials do not need to be handled in a dark room or under safe light.
Many heat-sensitive recording materials are suitable for a wide range of practical purposes because the imaging process is generally faster and easier than in silver halide photographic materials, such that direct visible images can be obtained by the application of a thermal pattern, for example. and thermal recording methods have been proposed. However, heat-sensitive recording materials that directly visualize images by applying a thermal pattern mainly utilize the fact that phenomena such as color development, discoloration, or fading caused by chemical reactions are initiated or accelerated by an increase in temperature. After formation, when the heat-sensitive component in the non-image area encounters heat, a reaction occurs, making it difficult to fix the image. Therefore, a thermal pattern is applied to the heat-sensitive layer, causing some kind of physical property change in the heat-sensitive component to create a latent image.
Materials and methods for obtaining visible images by methods such as removing non-image areas, selectively adding coloring materials, or selectively transferring them to the image-receiving layer can not only improve the above-mentioned drawbacks of heat-sensitive recording materials, but also improve conventional photosensitive recording materials. This type of heat-sensitive recording material and method has been proposed because it can be used as a material that is more convenient to handle for practical purposes such as copying, printing, and recording, to which the material is applied. For example, in Japanese Patent Publication No. 39-1743, the film forming temperature is
Heat-sensitive recording materials have been described that use an apparent film of discontinuous polymers at temperatures above 40°C. However, since the heat-sensitive recording material using this apparent film does not have a film formed before exposure, it is very weak and easily peels off. Furthermore, Japanese Patent Publication No. 44-22957 discloses a heat-sensitive layer containing a light-absorbing substance that changes the absorbed light and hydrophobic thermoplastic polymer particles dispersed in a hydrophilic binder in a ratio greater than 1:1. A method of obtaining an image by exposing to light and using differences in hydrophilicity and water permeability is described, and in the publication, polyethylene is suitably used as the hydrophobic thermoplastic polymer particles. However, when polyethylene is used as the heat-sensitive component, the film strength is low, and when the heat-sensitive layer is rubbed during development, exposed areas may be removed. Another disadvantage is that a large amount of energy is required for exposure. Further, JP-A-52-82431 describes a heat-sensitive recording material containing albumin as a heat-sensitive component. However, when albumin is used as a heat-sensitive component, the film strength is low and great care is required in handling during or even after development, making it impossible to put it into practical use. Furthermore, since the heat-sensitive layer swells during development, the resulting image is not clear. As described above, although recording materials processed with these developers have various characteristics, they do not necessarily have sufficient sensitivity and have drawbacks such as insufficient film strength. Therefore, a first object of the present invention is to provide a highly sensitive water-developable heat-sensitive recording material. A second object of the present invention is to provide a water-developable heat-sensitive recording material that is excellent in oil resistance and chemical resistance and capable of producing images with strong film strength. A third object of the present invention is to provide a water-developable heat-sensitive recording material that does not require the use of organic solvents or alkaline aqueous solutions during development. Furthermore, a fourth object of the present invention is to provide a water-developable heat-sensitive recording material having a heat-sensitive layer that provides clear visible image properties after exposure (visible image properties after exposure (recording) and before development). . The above-mentioned objects are a water-developable heat-sensitive recording material characterized by having a heat-sensitive layer on a support containing an ionomer resin applied as an aqueous dispersion and a water-soluble polymer compound as a binder. This is achieved by using According to a preferred embodiment of the present invention, the ionomer resin is α-olefin (especially ethylene).
and an α,β-unsaturated carboxylic acid (especially acrylic acid or methacrylic acid), which is ionically cross-linked with metal ions (especially Na ⁺ , Mg ⁺⁺ , Zn ⁺⁺ ), and The heat-sensitive layer of the present invention contains a water-soluble polymer compound (preferably polyvinyl alcohol, particularly preferably one containing 85 to 90% vinyl alcohol units) as a binder, and furthermore, contains an ionomer resin. The ratio of water-soluble polymer compounds is 3:2 to 9:1 by weight
It is to be. Any ionomer resin can be used as the ionomer resin used in the present invention, but
Preferred is a resin in which an α-olefin and an α,β-unsaturated carboxylic acid are ionically crosslinked with one or more metal ions. The α-olefin used in the base copolymer of this ionomer resin has the general formula RCH= _CH2 . Here, R is a hydrogen atom or an alkyl group, and the alkyl group preferably has 1 to 8 carbon atoms. That is, suitable olefins include ethylene, propylene,
These include 1-butene, 1-pentene, 1-hexene, 1-heptene, 3-methylbutene-1, 4-methylpentene-1, and the like. The α,β-unsaturated carboxylic acid, which is the second component of the copolymer, is preferably an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. That is, suitable α,β-unsaturated carboxylic acids include acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid,
Included are maleic acid, fumaric acid, and esters of these carboxylic acids, such as methyl acrylate, ethyl acrylate, methyl methacrylate, n-butyl methacrylate, dimethyl fumarate, diethyl itaconate, dimethyl maleate, and the like. These α-olefins or α,β-unsaturated carboxylic acids may be used singly or in combination of two or more types. Metal ions suitable for producing an ionomer resin from this copolymer are metal ions having a valence of 1 to 3. Suitable monovalent metal ions include Na ⁺ , K ⁺ , Li ⁺ , Cs ⁺ , Ag ⁺ , Hg ⁺ , and divalent metal ions include Be ⁺⁺ , Mg ⁺⁺ , Ca ⁺⁺ , Sr ⁺⁺ , Ba ^+
+ , Cu ⁺⁺ , Cd ⁺⁺ , Hg ⁺⁺ , Sn ⁺⁺ , Pb ⁺⁺ , Fe ⁺⁺ , Co ⁺⁺ ,
Ni ⁺⁺ , Zn ⁺⁺ , Al ⁺⁺⁺ , Sc ⁺⁺ as trivalent metal ions
⁺ , Fe ⁺⁺⁺ , and Y ⁺⁺⁺ . Among these, Na ⁺ , Mg ⁺⁺ or Zn ⁺⁺ are preferred in the present invention. Preferred among these ionomer resins are ionomer resins obtained by ionically crosslinking ethylene and acrylic acid or methacrylic acid with Na ⁺ , Mg ⁺⁺ or Zn ⁺⁺ . Regarding the production method of the ionomer resin used in the present invention, please refer to Japanese Patent Publication No. 39-6810 and Japanese Patent Publication No. 42-6810.
No. 15768, JP-A-49-31556, JP-A-49-121891
It is sufficient to follow the method described in each publication of the issue. The heat-sensitive recording material according to the present invention may contain some binder, especially a water-soluble polymer compound. Preferred water-soluble polymer compounds include, for example, gelatin, glue, casein, zein, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl starch, gum arabic, sucrose octaacetate, ammonium alginate, and alginic acid. Examples include soda, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylamine, polyethylene oxide, polystyrene sulfonic acid, and polyacrylic acid. In the present invention, polyvinyl alcohol is preferred, and polyvinyl alcohol with a saponification degree of 85 to 90% is particularly preferred. The amount of water-soluble polymer compound can vary up to 80%, but is preferably from 10% to 60%. If the hydrophilic binder content is less than 10%, the solubility of the non-image area is insufficient, and if it exceeds 60%, the strength of the image area may be insufficient. The ionomer resin preferred for the heat-sensitive recording material according to the present invention can be applied by an aqueous dispersion containing a water-soluble polymer compound as a hydrophilic binder. This aqueous dispersion can be obtained by dispersing the ionomer resin in pressurized and heated water. This method is described in detail in Japanese Unexamined Patent Publication No. 51-62890. According to another method, the ionomer resin can be obtained by dispersing a finely ground ionomer resin in water using a surfactant or a hydrophilic protective colloid such as polyvinyl alcohol.
The size of the ionomer resin particles in the dispersion is 0.01
~50μ is sufficient. Preferably, the size is 0.05 to 2μ. If the particles are larger than 2μ, the resolution will decrease,
If it is smaller than 0.05μ, sensitivity may decrease. Although the mixing ratio of the ionomer resin used in the present invention and the water-soluble polymer compound (especially polyvinyl alcohol) as a binder is not limited, it is preferably 2:3 to 9:1 by weight. If the mixing ratio of the ionomer resin is outside this range, that is, if the mixing ratio of the ionomer resin is too low, the strength of the image area may be insufficient, and if it is too high, the solubility of the non-image area may not be sufficient. . The ionomer resin used in the present invention is applied as an aqueous dispersion, and the content of the ionomer resin in this aqueous dispersion is 1 to 1% of water.
100% is desirable; if it is less than 1%, a sufficient film thickness will not be obtained when applied;
If it exceeds %, the viscosity may become high and handling may become difficult. It is desirable to add pigments and dyes to the heat-sensitive layer of the present invention in order to effectively utilize energy such as visible light and infrared rays. The pigment or dye used in the present invention can be any pigment or dye that can convert patterns of X-rays, ultraviolet rays, visible light, infrared rays, etc. into thermal patterns, but in particular, carbon graphite, carbon black, and phthalocyanine-based pigments can be used. Pigments, iron powder, graphite powder, iron oxide powder, lead oxide,
Pigments that absorb in the visible and near-infrared regions, such as silver black, are preferred, and carbon black is particularly preferred. When the heat-sensitive layer of the present invention uses an ionomer resin as a heat-sensitive component, a water-soluble polymer compound as a hydrophilic binder, and, if necessary, a pigment (especially carbon black, etc.) or dye, the ionomer resin and It is desirable that the mixing ratio of the sum of the binders and the pigment or dye is 1:1 to 20:1 by weight. Further, the dyes and pigments used in the present invention can also be applied by dissolving or dispersing them in advance in the ionomer resin. Supports used in the present invention include paper, paper laminated with plastics (e.g. polyethylene, polypropylene, polystyrene, etc.),
Metal plates such as aluminum, zinc, copper, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate/butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. There are plastic films, etc. Among these supports, polyethylene terephthalate or aluminum plates are preferred. In particular, aluminum plates are grained, treated with sodium silicate,
It is preferable that the surface be subjected to a surface treatment such as immersion treatment in an aqueous solution of potassium fluorozirconate or phosphate, or anodization treatment. In the present invention, an intermediate layer made of gelatin, casein, polyvinyl alcohol, ethyl cellulose, phenolic resin, diazoresin, styrene-maleic anhydride copolymer, polyacrylic acid, etc. is optionally provided between the support and the heat-sensitive layer. ,
It can be provided for the purpose of improving adhesion between the support and the heat-sensitive layer or preventing pinholes. Furthermore, in order to prevent scratches on the surface of the heat-sensitive layer or improve vacuum adhesion, an overcoat layer that dissolves or swells during development may be provided in the present invention. This overcoat layer may be mechanically matted or a resin layer containing a matting agent. Matting agents include silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, starch, polymer particles (such as polymethyl methacrylate,
(particles of polystyrene, phenolic resin, etc.) and matting agents described in US Pat. No. 2,701,245 and US Pat. No. 2,992,101. Two or more of these can be used in combination. The resin used in the overcoat layer containing the matting agent is appropriately selected. Specifically, for example, gum arabic, glue, gelatin, casein, celluloses (e.g., viscose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc.), starches (e.g., soluble starch,
modified starch, etc.), polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polyacrylamide, polyvinyl methyl ether, polyvinylpyrrolidone, polyamide, etc. Two or more of these can be used in combination. In order to produce the heat-sensitive recording material according to the present invention, for example, an aqueous ionomer resin dispersion, a hydrophilic binder, and a pigment or dye are mixed, and the mixture is mixed with a ball mill,
Disperse uniformly using an ultrasonic dispersion machine, etc. The obtained dispersion is coated on the support to a thickness of 1 to 50 μm, preferably 1 to 15 μm, and dried at a temperature of 30 to 50°C. The heat-sensitive recording material according to the present invention does not require the use of organic solvents, alkaline aqueous solutions, etc. during development, and can be processed only with an aqueous solution. However, it goes without saying that the present invention does not exclude treatment with an alkaline aqueous solution or the like. According to the first method, an image can be obtained by washing away the remaining transparent, soluble portion of the recording material. According to a second method, an image can be obtained by immersing the recording material in an aqueous dye solution and allowing the dye to diffuse into the areas that remain hydrophilic. According to a third method, an image can be obtained by transferring the remaining hydrophilic portions of the recording material to an image-receiving material in a wet or dry state. According to the fourth method, hydrophilicity -
A plurality of copies can be obtained by using a recording material with a difference in hydrophobicity in lithographic printing. The heat-sensitive recording material according to the present invention can be subjected to close exposure using a xenon lamp, halogen lamp, tungsten lamp, etc. as a light source, but preferably the light emission time is about 1/100 second or less and the light intensity in the infrared region is low. A large flash light source is preferred. Also semiconductor laser, Ar or He-Ne
Exposure with laser light such as the like can also be performed. In addition to obtaining a high-resolution lithographic film at low cost, the present invention can be used to (1) obtain a lithographic master using water developability, and (2) energize the heat-sensitive recording material of the present invention. (3) By scanning and exposing laser light and developing with water, it can be used as a facsimile film or lithographic master. It has the above advantages. EXAMPLES The present invention will be specifically explained below using Examples, but the embodiments of the present invention are not limited thereby. Example 1 Carbon black (average particle size 30 mμ) 2 parts by weight Copolen Latex L-4000 [ionomer resin
40% aqueous dispersion, manufactured by Asahi Dow Co., Ltd.] 5 parts by weight 10% Gohsenol GL-05 [polyvinyl alcohol, degree of saponification 86.5-89.0, manufactured by Nippon Gosei Kagaku Co., Ltd.] Aqueous solution 20 parts by weight Water 13 parts by weight Above weight composition by glass beads by ratio
Thickness with gelatin subbing layer, dispersed for 30 minutes
It was coated onto a 100μ polyethylene terephthalate (PET) film using a wire spar so that the weight after drying was about 45 mg/dm ² . This recording material was dried at 50° C. or lower to prepare a sample of the present invention. A negative original is placed on the sample of the present invention and a xenon flash light source (manufactured by Riso Kagaku Kogyo Co., Ltd., RISO,
TORAPEN UP FX-120) and exposed from the original side with an energy of 0.7 J/cm ² . As a result, images with different surface reflectances appeared clearly on the sample surface, and it was revealed that the sample of the present invention had excellent exposure visible image properties. Next, the above-mentioned sample of the present invention was immersed in water and the heat-sensitive layer was rubbed with a sponge, so that the unexposed areas were dissolved and removed, and a clear black positive image was obtained. Example 2 A dispersion of the ionomer resin shown in Table 1 was applied onto a 100 μm thick polyethylene terephthalate film having a gelatin undercoat layer so that the dry paper film thickness was approximately 45 mg/dm ² . Samples of the present invention were prepared by drying at a temperature of 50° C. or lower. A negative original was superimposed on this sample of the present invention, and a xenon flash light source RISO TRAPEN UP FX-120 was used.
[manufactured by Riso Kagaku Kogyo Co., Ltd.] was used to expose the document from the original side. Next, this exposed sample of the present invention was immersed in water and developed by rubbing with a sponge to obtain an image. At this time, the exposure energy was set to 0.50, 0.70, 0.90,
It was changed to 1.05, 1.25 and 1.50J/ ^cm2 . The dispersion liquid for forming the heat-sensitive layer is a resin (first
(shown in the table), Gohsenol GL-05 and Carbon Black (average particle size 30 mμ) in a weight ratio of 7:
The 3:5 composition was dispersed with glass beads for 30 minutes. Comparative samples 1 to 16 were prepared in exactly the same manner as the sample of the present invention in Example 2, except that only the resin was shown in Table 1. For the sensitivity in Table 1, the lowest energy at which an image can be obtained by development is taken as the sensitivity. That is, the lower the exposure energy amount, the higher the sensitivity, and the symbol marked with - indicates that no image was obtained even with an exposure of 1.50 J/cm ² .

【table】

[Table] From the results in Table 1, it can be seen that the samples of the present invention have higher sensitivity than the comparative samples. In addition, for each sample for which an image was obtained with an exposure energy of 1.50 J/cm ² or less, a film cleaner [manufactured by Chugai Photo Yakuhin Co., Ltd.] was soaked in absorbent cotton and the heat-sensitive layer was rubbed. was observed to be immersed, whereas the samples of the present invention were not immersed. Example 3 Printex200 [Carbon black 45% aqueous dispersion,
Degussa] 1 part by weight Copolene Latex L-2000 2 parts by weight 10% gelatin aqueous solution 3 parts by weight Water 4 parts by weight The composition with the above weight ratio was dispersed for 3 minutes using an ultrasonic dispersion machine, and the thickness of the gelatin undercoat layer was determined.
A wire bar on a 100μ polyethylene terephthalate (PET) film reduces the weight after drying to approx.
A sample of the present invention was prepared by coating the solution at a concentration of 45 mg/dm ² and drying at 50° C. or lower. When this was exposed and developed in the same manner as in Example 1, a clear positive image was obtained. Example 4 The sample of the present invention obtained in Example 1 was exposed in the same manner as in Example 1, then soaked with water and strongly pressed against receiver paper. When this was immediately peeled off, a negative print was obtained in which the water-soaked unexposed areas were transferred onto the receiving paper. Example 5 A dispersion having the same composition as in Example 1 was coated with a wire bar on a paper support coated with polyethylene and treated with corona discharge so that the weight after drying was about 20 mg/dm ² , and the temperature was below 50°C. and dried to prepare a sample of the present invention. This sample was then exposed to light and developed in the same manner as in Example 1, and a clear positive print was obtained. Example 6 Carbon black (average particle size 30 mμ) 1 part by weight Copolene Latex L-2000 2 parts by weight 10% Gohsenol GL-05 aqueous solution 3 parts by weight Water 4 parts by weight A mixture with the above weight ratio was dispersed and coated in the same manner as in Example 1. It was dried to prepare a sample of the present invention. This sample was then exposed and developed in the same manner as in Example 1, except that the exposure energy was 0.5 J/cm ² , and a clear positive image was obtained. This sample of the present invention was subjected to scanning exposure using a 50 mW He-Ne laser (Model 125A manufactured by Spectra Physics). When this sample was developed in the same manner, a clear image was obtained in which only the scanned portion remained. Example 7 Chrome Phthalocyanine-4GN (copper phthalocyanine pigment, manufactured by Ciba Geigy) 2 parts by weight Copolene Latex L-6000 [Ionomer resin
40% aqueous dispersion, manufactured by Asahi Dow Co., Ltd.] 15 parts by weight 10% Gohsenol GL-05 aqueous solution 10 parts by weight Water 25 parts by weight A mixture with the above weight ratio was dispersed, coated and dried in the same manner as in Example 1. A sample of the invention was prepared. Next, this sample was exposed to light with an energy of 1.5J/cm ²
When development was carried out in the same manner as in Example 1 except for the above, a clear blue positive image was obtained. Example 8 The sample obtained in Example 6 was exposed in the same manner as in Example 7. This was pressed onto an adhesive tape and immediately peeled off. As a result, a negative image was obtained on the adhesive tape and a positive image was obtained on the sample.

Claims (1)

[Scope of Claims] 1. A water-developable heat-sensitive recording characterized by having, on a support, a heat-sensitive layer containing an ionomer resin applied as an aqueous dispersion and a water-soluble polymer compound as a binder. material. 2 Ionomer resin has α-olefin and α,β
- A water-developable heat-sensitive recording material according to claim 1, which is a resin obtained by ionically crosslinking a copolymer with an unsaturated carboxylic acid using metal ions. 3. The water-developable heat-sensitive recording material according to claim 2, wherein the α-olefin is ethylene. 4. The water-developable heat-sensitive recording material according to claim 2, wherein the α,β-unsaturated carboxylic acid is acrylic acid or methacrylic acid. 5. The water-developable heat-sensitive recording material according to claim 2, wherein the metal ion is Na ⁺ , Mg ⁺⁺ or Zn ⁺⁺ . 6. The water-developable heat-sensitive recording material according to claim 1, wherein the water-soluble polymer compound is polyvinyl alcohol. 7. The water-developable heat-sensitive recording material according to claim 6, wherein the polyvinyl alcohol contains 85 to 90% vinyl alcohol units. 8. The water-developable product according to claim 1, 6 or 7, characterized in that the ratio of the water-soluble polymer compound to the ionomer resin is 3:2 to 1:9 by weight. Heat-sensitive recording material.