JPH0887138A - Direct drawing planographic printing plate - Google Patents

Abstract

PURPOSE: To decrease toner fog and contamination in print by using a mixture of three kinds of zinc oxide produced by dry method, zinc oxide produced by wet method and conductive zinc oxide as the zinc oxide in an image receiving layer. CONSTITUTION: This printing plate has a water-resistant supporting body and an image receiving layer which contains zinc oxide and resin as the main component and is formed on the one side surface of the water-resistant supporting body. The zinc oxide in the image receiving layer is a mixture of three kinds of zinc oxides produced by dry method, zinc oxide produced by wet method, and conductive zinc oxide. The conductive zinc oxide is produced by adding a small amt. of oxides of aluminum, titanium, gallium, indium, tin or the like and calcining the result at high temp. Therefore, by adding conductive zinc oxide to zinc oxide produced by dry method and wet method, the surface electric resistance of the image receiving layer is decreased and triboelectric charging is hardly caused in the image receiving layer when the plate material is peeled from the photoreceptor drum. Thus, scattering of the toner in an nonimage part is decreased and toner fog and contamination in print can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic transfer system such as a copying machine or a laser printer, or a thermal transfer printer, a typewriter, or a plate material for direct drawing type lithographic printing plates for making a plate by hand drawing. More specifically, the present invention relates to a direct-drawing type planographic printing plate material having less printing stains.

[0002]

2. Description of the Related Art With the recent development of office equipment and the progress of office automation, in the light printing field, a direct drawing type planographic printing plate material that can be easily plate-made by a copying machine, a laser printer, a thermal transfer printer, etc. is used. Printing methods are rapidly spreading. A conventional direct-drawing type planographic printing plate material is one in which an image receiving layer made of an inorganic pigment, a water-soluble resin, a water-proofing agent, etc. is provided on a support made of paper, plastic film, etc. which has been subjected to water resistance treatment. Is. In such a direct drawing type planographic printing plate material, a lipophilic ink is formed on the image receiving layer using a typewriter or handwriting, or a toner formed on the electrophotographic photosensitive member. The image can be transferred to the image receiving layer and heat-fixed to form a lipophilic image, or the image can be heat-melt transferred from an ink ribbon with a thermal transfer printer to form a lipophilic image.

Such a direct drawing type planographic printing plate material becomes a printing plate by desensitizing the non-image area of the printing plate material with an etching solution. Examples of a direct-drawing type lithographic printing plate material in which an image receiving layer comprising an inorganic pigment, a water-soluble resin, a water-proofing agent and the like are provided on a water-resistant support are, for example, JP-B-40-2358.
1, JP-A-48-9802, JP-A-57-2051
96, JP-A-60-2309, JP-A-57-179.
1, JP-A-57-15998, JP-A-57-969.
No. 00, JP-A-63-166590, JP-A-63-1
66591, JP-A-63-256493, JP-A-6
It is disclosed in gazettes, such as 3-317388 and Unexamined-Japanese-Patent No. 1-114488. The above-mentioned conventional direct-drawing type planographic printing plate materials are now in decline. The first cause thereof is a drawback that toner is scattered during transfer of a toner image in the plate making process of the electrostatic transfer system to cause fogging in a non-image portion, which also appears as background stain in printing.

The cause of toner fog is that toner is scattered to the non-image area when the photosensitive drum and the plate material are separated. Therefore, various studies have been conducted on the assumption that toner fogging can be improved by lowering the surface electric resistance of the image receiving layer, but all of them have drawbacks. Japanese Patent Laid-Open No. 5-246166 proposes to use a mixture of zinc oxide manufactured by a wet method and zinc oxide manufactured by a dry method for improving toner fogging. When zinc oxide produced by the wet method is mixed, the surface electric resistance of the image receiving layer is slightly lowered and the toner fog is slightly improved, but it is insufficient, and when a large amount of zinc oxide produced by the wet method is blended. However, it has a drawback that the dispersibility of the pigment is significantly deteriorated.

JP-A-6-48057 proposes to contain an alcohol-soluble antistatic agent. However, desensitization deteriorates when an antistatic agent is added,
It had a drawback that printing stains tended to occur. According to the research results of the present inventors, when only conductive zinc oxide is used, the surface electric resistance of the image receiving layer is lowered and the toner fog is improved, but the image is easily peeled off, and therefore, it is used as a plate material for direct lithographic printing. It was unsuitable.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a direct-drawing type planographic printing plate material having less toner fogging and good printing stains in the electrostatic transfer type plate making.

[0007]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that zinc oxide produced by the dry method and oxidation produced by the wet method as zinc oxide in the image receiving layer. The present invention has been achieved by finding that the above problems can be solved by using a mixture of three kinds of zinc and conductive zinc oxide.

That is, the direct drawing type lithographic printing plate material of the present invention comprises a water resistant support and an image receiving layer formed on one surface of the water resistant support and containing zinc oxide and a resin as main components. Wherein the zinc oxide in the image receiving layer is zinc oxide produced by a dry method and zinc oxide produced by a wet method,
And a mixture of three kinds of conductive zinc oxide.

By adding conductive zinc oxide to the zinc oxide produced by the dry method and the wet method, the surface electric resistance of the image receiving layer is lowered, and the image receiving layer is triboelectrically charged when the photosensitive drum and the plate material are separated. It is considered that the toner fogging and the print stain are improved by reducing the scattering of the toner to the non-image area.

The zinc oxide production method by the dry method includes the American method and the French method. In the American method, a reducing agent such as coke is added to zinc ore (francrinite: ZnFe ₂ O ₄ ) and roasted, and the generated zinc vapor is air-oxidized. In addition, according to the French law, high-purity metallic zinc is approximately 1000
After heating to ℃, the generated zinc vapor is burned in an oxidizing atmosphere (usually air) to produce zinc oxide. Any zinc oxide produced by these methods can be used in the present invention.

The method for producing zinc oxide by the wet method includes a method of thermally decomposing a zinc salt such as zinc carbonate, a method of directly precipitating zinc oxide in a liquid while neutralizing an alkaline solution of the zinc salt with an acid, and a method of zinc. There is a method in which an acidic salt solution is directly precipitated in a liquid while being neutralized in an alkali. Generally, an acidic solution of zinc salt (zinc sulfate solution or zinc chloride solution)
Then, it is reacted with an alkali such as soda ash, washed with water, filtered, dried, baked, and pulverized to produce. Zinc oxide produced by the wet method is generally called activated zinc white, and has a lower photoconductivity than zinc oxide produced by the dry method because it contains impurities.

Conductive zinc oxide is produced by adding a small amount of oxides of aluminum, titanium gallium, indium, tin, etc. to zinc oxide and firing it at a high temperature.
A lattice defect is formed to give conductivity. The conductive zinc oxide used in the present invention may be produced by any method.

In the direct drawing type planographic printing plate material of the present invention,
The content of total zinc oxide contained in the image receiving layer is preferably 70 to 90% by weight based on the total weight of the image receiving layer. When the total zinc oxide content is less than 70% by weight,
The desensitizing ability is inferior, and printing stains are likely to occur. If it exceeds 90% by weight, the adhesive strength will be poor and the image receiving layer may be easily peeled off during printing.

The content of zinc oxide produced by the dry method in the image receiving layer is 10 to 70 based on the total weight of the image receiving layer.
It is preferably in the weight%. This content is 10% by weight
When it is less than 7, the desensitizing ability is insufficient, and 7
When it exceeds 0% by weight, the surface electric resistance of the image receiving layer becomes high, and fogging occurs in the non-image area. The content of the zinc oxide produced by the wet method in the image receiving layer is preferably 5 to 40% by weight based on the total weight of the image receiving layer. If the content is less than 5% by weight, the toner fogging is insufficient, and if it exceeds 40% by weight, the dispersibility is poor.
Moreover, the desensitizing ability is insufficient, and as a result, printing stains occur, which is unsuitable as a direct-writing type planographic printing plate material.

The content of the conductive zinc oxide in the image receiving layer is preferably 5 to 50% based on the total weight of the image receiving layer. If the content is less than 5%, the surface electric resistance of the image-receiving layer will not be sufficiently lowered, so that the toner fog will not be improved, and if it exceeds 60%, the adhesiveness of the image-receiving layer will deteriorate. The image peels off during printing.

The dry weight of the image receiving layer of the plate material for direct drawing lithographic printing according to the present invention is preferably 4 to ²⁰ g / m ² . When it is less than 4 g / m ² , the desensitizing ability of the plate material for direct drawing type lithographic printing obtained is insufficient and the image is easily peeled off during printing of the image receiving layer. On the other hand, when it exceeds 20 g / m ² , the cost is high and the surface electric resistance of the image receiving layer is high, so that toner fogging is deteriorated in plate making by the electrostatic transfer system.

The resin used in the image-receiving layer in the direct-drawing type lithographic printing plate material of the present invention includes starch, starch derivatives, carboxymethyl cellulose, cellulose derivatives such as hydroxymethyl cellulose, polyvinyl alcohol, modified polyvinyl alcohol, casein, And water-soluble resins such as ammonium acrylate, and water-dispersible hydrophobic emulsion-type resins such as acrylic resins, SBR, NBR, and vinyl acetate-ethylene copolymers, and these resins can be used. Can be used alone or in combination of two or more. When only the above water-dispersible resin is used as the resin, it is desirable to use a suitable amount of a water-proofing agent in combination with it in order to improve the printing durability of the direct drawing type printing plate material obtained. As the waterproofing agent, glyxal, polyamide resin, epoxy compound or the like can be used.

Further, as other resins used in the image receiving layer, solvent-soluble (water-insoluble) resins such as polyester resin, acrylic resin, epoxy resin, polycarbonate resin, and butyral resin can be mentioned. In this case, the coating material for the image receiving layer can be prepared using a solvent such as toluene.

The content of the resin in the image receiving layer is preferably 30% by weight or less, and more preferably 10 to 25% by weight, based on the total weight of the image receiving layer. When the binder content exceeds 30% by weight, desensitization of the non-image area of the obtained direct drawing type planographic printing plate material is insufficient and stains are likely to occur during printing.

As a method for applying the image receiving layer coating material, a Meyer bar method, an air knife method, a blade method, a reverse roll method, a slit die method or the like can be used. Of course, it is not limited to these.

The support used in the present invention is required to have water resistance that can withstand the influence of water during hydrophilic treatment and offset printing. A strong size paper provided with a water resistant layer, a plastic film, a laminate of strong size paper and aluminum foil or a plastic film, and the like can be used. Further, a back layer may be provided on the back surface of the support to prevent curling.

The water resistant layer and the back layer are formed by using an emulsion type resin such as acrylic resin, SBR or NBR. These resins may be used alone or in combination of two or more. Further, an appropriate amount of pigment may be contained in these layers. In the water resistant layer and the back layer, if necessary, an auxiliary additive component, for example,
There is no problem in adding a dispersant, a conductive agent, and a water resistant agent for strengthening water resistance. The dry weight of the water-resistant layer is preferably more preferably in the range of 3 to 30 g / m ² is 5 to 20 g / m ^2. 3 g / m ²
If the amount is smaller, the surface coating on the support is thin and sufficient water resistance cannot be obtained. On the other hand, if the amount is more than 30 g / m ² , the cull becomes too large. As the coating method of the water resistant layer coating, the same method as in the image receiving layer can be used.

The dry weight of the back layer is 3 to 30 g / m.
It is preferable that it is within the range of ² , more preferably 5 to 2.
It is 0 g / m ² . If it is less than 3 g / m ² , curling will occur. Also, if it is more than 30 g / m ² , the curl becomes too large. The coating method for the coating composition for the coating layer may be the same as that for the image receiving layer.

[0024]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples. In addition, "part" in an Example represents a "weight part."

Example 1 A coating material having the following composition was applied on a surface of a substrate made of paper which was wet-strengthened and internally sized to have a dry weight of 10 g / m ^2.
And the coating was dried to form a water resistant layer on the image receiving layer side. Water-resistant layer forming coating composition Ingredient Weight kaolinite clay - dispersion (50% solids, trademark: Hydro Gloss 90, made by Huber) 30 parts of emulsion type acrylic resin (40% solids, trademark: Aron A- 104, manufactured by Toagosei Kagaku Kogyo Co., Ltd.) 50 parts SBR (solid content 50%, trademark: Nipol LX-415, manufactured by Nippon Zeon Co., Ltd.) 40 parts water 50 parts According to JIS P-8140
It was 0.5 g / m ² when measured in accordance with.

Next, a coating composition having the following composition was applied on the back surface of the paper substrate so as to have a dry weight of 15 g / m 2, and dried to form a back layer. Back layer composition forming the coating material for forming a partial Weight kaolinite clay - dispersion (50% solids, trademark: Hydro Gloss 90, made by Huber) 60 parts emulsion type acrylic resin (solid content 45%, trademark: Bonron S-482 , Mitsui Toatsu Chemicals) 45 parts Water 50 parts

Next, the following composition was prepared and dispersed by a sand grinder, and the coating composition was applied onto the water resistant layer so that the dry weight was 7 g / m ² , and the image receiving Was formed. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) zinc oxide prepared in 50 parts of wet process (trademark activated zinc white, Sakai Chemical Industry) 25 parts Conductive Zinc Oxide (trademark: 23-K, manufactured by Shiramizu Chemical Industry) 10 parts Acrylic resin (solid content 50%, trademark: Acridic A-405, manufactured by Dainippon Ink and Chemicals Industry) 28 parts Toluene 86 copies

A copying machine (trademark: Fuji X) was placed on the image-receiving layer of the direct drawing type planographic printing plate thus prepared.
The image was transferred using erox 5026) and the plate was prepared by a conventional method. In this plate-making process, the fogging of the non-image area due to toner scattering was observed with a microscope. The results are shown in Table 1. Further, the image density of the toner adhesion amount of a solid image portion of 5 cm × 5 cm was measured using a Macbeth reflection densitometer.
The results are shown in Table 1. This direct drawing lithographic printing plate material
After desensitizing with a cyan-based etchant manufactured by K, printing was performed using an offset printing machine to evaluate print stains.
The results are shown in Table 1. Further, the surface electric resistance of the image receiving layer is measured by a super insulation resistance meter (trademark: High Resistance).
It was measured using a Meter Model 4329A manufactured by Yokogawa Hewlett Packard. The results are shown in Table 1.

Example 2 The same support provided with a water resistant layer and a back layer as in Example 1 was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) zinc oxide prepared in 25 parts of wet process (trademark activated zinc white, Sakai Chemical Industry) 25 parts Conductive Zinc Oxide (trademark: 23-K, manufactured by Shiramizu Chemical Industry) 35 parts Acrylic resin (solid content 50%, Trademark: Acridic A-405, manufactured by Dainippon Ink and Chemicals Industry) 28 parts Toluene 86 parts The direct drawing type planographic printing plate material thus prepared was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 The same support as in Example 1 provided with a water resistant layer and a back layer was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) zinc oxide prepared in 60 parts of wet process (trademark activated zinc white, Sakai Chemical Industry) 10 parts Conductive Zinc Oxide (trademark: 23-K, manufactured by Shiramizu Chemical Industry) 15 parts Acrylic resin (solid content 50%, Trademark: Acridic A-405, Dainippon Ink and Chemicals Industry) 28 parts Toluene 86 parts The direct drawing type planographic printing plate material thus prepared was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 The same support provided with the water resistant layer and the back layer as in Example 1 was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) 85 parts of acrylic resin (50% solids, trademark: ACRYDIC A-405, (Manufactured by Dainippon Ink and Chemicals, Inc.) 28 parts Toluene 86 parts The direct drawing type planographic printing plate material thus prepared was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 The same support provided with the water resistant layer and the back layer as in Example 1 was used. Next, the following composition was prepared and dispersed with a sand grinder. As a result, many agglomerates were formed, and the image receiving layer could not be formed with this paint. Image zinc oxide produced by a composition Ingredient Weight wet method of the receiving layer forming coating material (trademark activated zinc white, manufactured by Sakai Chemical Industry Co.) 85 parts of acrylic resin (50% solids, trademark: ACRYDIC A-405, Dainippon Ink and Chemicals) 28 parts Toluene 86 parts

Comparative Example 3 The same support as in Example 1 provided with a water resistant layer and a back layer was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Composition Ingredient Weight electroconductive zinc oxide of the image-receiving layer-forming coating material (TM: 23-K, Hakusuikagakukogyo Ltd.) 85 parts Acrylic resin (50% solids, trademark: ACRYDIC A-405, Dainippon Ink and Chemicals Kogyo Co., Ltd.) 28 parts Toluene 86 parts The direct drawing type lithographic printing plate material thus prepared was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 The same support as in Example 1 provided with a water resistant layer and a back layer was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) zinc oxide prepared in 50 parts of wet process (trademark activated zinc white, Sakai Chemicals) 35 parts Acrylic resin (solid content 50%, trademark: Acridic A-405, Dainippon Ink and Chemicals) 28 parts Toluene 86 parts Direct drawing type lithographic printing plate material thus prepared, Evaluation was performed by the same method as in Example 1. The results are shown in Table 1.

Comparative Example 5 The same support as in Example 1 provided with a water resistant layer and a back layer was used. Next, the following composition was prepared and dispersed by a sand grinder, and the coating was applied on the water resistant layer so that the dry weight was 7 g / m ² , to form an image receiving layer. Then. Zinc oxide produced by a composition Ingredient Weight dry method of the image-receiving layer-forming coating material (TM: SAZEX # 2000, manufactured by Sakai Chemical Industry Co.) 50 parts electroconductive zinc oxide (trademark: 23-K, manufactured by Hakusuikagakukogyo) 35 parts Acrylic resin (solid content 50%, trademark: Acridic A-405, manufactured by Dainippon Ink and Chemicals, Inc.) 28 parts Toluene 86 parts The direct drawing type lithographic printing plate material thus prepared was used as in Example 1. Evaluation was performed by the same method. The results are shown in Table 1.

Comparative Example 6 The same support as in Example 1 provided with the water resistant layer and the back layer was used. Next, the following composition was prepared and dispersed with a sand grinder. As a result, many agglomerates were formed, and the image receiving layer could not be formed with this paint. Zinc oxide produced by a composition Ingredient Weight wet method in the image-receiving layer-forming coating material (trademark activated zinc white, manufactured by Sakai Chemical Industry) 50 parts electroconductive zinc oxide (trademark: 23-K, manufactured by Hakusuikagakukogyo) 35 parts Acrylic resin (solid content 50%, trademark: Acridic A-405, 28 parts made by Dainippon Ink and Chemicals) Toluene 86 parts

[0037]

[Table 1]

[0038]

According to the present invention, a direct drawing type planographic printing plate material having less toner fogging and good printing stains was obtained. This printing plate material largely contributes to rationalization in the fields of office printing and light printing.

Claims (1)

[Claims] 1. A water-resistant support, and an image-receiving layer formed on one surface of the water-resistant support and containing zinc oxide and a resin as main components. The zinc oxide in the image-receiving layer is A direct drawing type lithographic printing plate material, which is a mixture of three kinds of zinc oxide manufactured by a dry method, zinc oxide manufactured by a wet method, and conductive zinc oxide.