JPS5816892A - Base material for negative plate for electro photographic lithographic printing - Google Patents

Abstract

PURPOSE:To raise the water resistance, blister resistance, and printing durability of the base material for electrophotographic lithographic printing negative plate by using a mixed adhesive composed of an acrylic resin emulsion and a synthetic rubber resin in bonding a metal foil with a paper for the base material. CONSTITUTION:In a base material for electrophotographic and lithographic printing negative plate in which an image receiving layer containing a photo- conductive substance is provided directly or through an intermediate layer on the metal foil layer of a metal foil-laminated paper as a base material, an adhesive composed of a 50:50-97:3 mixture (on dry weight basis) of an acrylic resin emulsion and a synthetic rubber resin is used for bonding the metal foil with the paper. Thus, the base plate for electrophotographic and lithographic printing negative plate, having improved water resistance against moistening water coming from the end part of the printing negative plate during printing period, an improved blister resistance, and improved printing durability, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a substrate for an electrophotographic printing original plate. Generally, an electrophotographic lithographic printing original plate is constructed by providing a layer containing an inorganic or organic optical semiconductor on a base material having characteristics such as water resistance and conductivity.

Sheet-like materials such as paper, gold leaf, film, or composites thereof are used as the base material, but when paper is used, it is treated to make it waterproof, and to improve the quality of electrophotographic images. A coating layer containing an inorganic electrolyte such as sodium chloride, potassium chloride, calcium chloride, or an organic polymer electrolyte such as a quaternary ammonium salt, which is usually called a conductive agent, is provided.

However, when a lithographic printing plate is made using paper that has been treated in this way as a base material, the dampening water applied during printing causes problems.
Even with water-resistant treatment, plate elongation is unavoidable. This causes problems such as wrinkles on the plate during printing, misregistration of printed matter, and irregular dimensions of the Nfi wire.

Instead of paper, a metal foil such as aluminum, zinc, or copper is bonded with an adhesive [7] (hereinafter referred to as metal foil laminated paper), and a layer of metal foil is placed between the photosensitive layer and the paper. It is possible to satisfy the water resistance and obtain a printing original plate with good dimensional stability (for example, Japanese Patent Publications No. 38-17249, No. 41-242, No. 41-242).
12432, etc.).

As an adhesive for metal foil laminated paper, for example, aluminum foil laminated paper which is widely used industrially, vinyl acetate resin, acrylic resin, polyolefin resin, urethane resin, etc. are usually used.

These are applied as a water-based paint in the form of an emulsion or as a solvent-based paint using an appropriate solvent, and then applied between the layers of metal foil and paper to perform lamination.

Water-soluble resins such as casein, poval, and starch are also used as adhesives.゛In addition, as a laminating method, wax resin, polyolefin resin (polyethylene, polypropylene, ethylene-
Hot-melt methods and extrusion coating methods using resins that melt when salted (such as vinyl acetate copolymer resins and ionomers) and extrusion coating methods are also commonly used.

The present inventors manufactured an electrophotographic printing original plate using metal foil laminated paper as a base material and investigated its practicality.The following two main physical properties were found to be required for the adhesive between the metal foil and the paper. It is a point.

(1) During plate making, during thermal running of the developer, blister (breakage of opening and opening, also called blistering) occurs due to softening of the adhesive and insufficient adhesive strength.

(2) It should not be destroyed by water entering from the edge of the original printing plate during printing. That is, the adhesive layer dissolves or swells due to dampening water, and the adhesion strength decreases (IP), so that the phenomenon that the paper and metal foil peel off during printing and the printing original plate is destroyed does not occur. thing.

For example, metal foil-covered paper produced by the hot-melt method or extrusion coating method is completely inappropriate in view of the above point (1). However, the above problem (1) can be almost solved by taking measures such as reducing the coating thickness in the back layer or applying a mixture of breathable substances. However, the above (1)
, (2), it is currently impossible to find a sufficient solution that satisfies both of the above.

According to the experimental results of the present inventors, a relatively practical product was obtained when an acrylic tree 11'A emulsion was used as an adhesive between gold leaf and paper. However, this is still unsatisfactory, and when the number of printed sheets increases, it is particularly unsatisfactory in point (2). Original plates based on metal foil laminated paper using synthetic rubber adhesive tend to cause blisters during plate making, but they have sufficient resistance to submerged water that enters from the edges during printing. . As a result of further research, we succeeded in obtaining a practically excellent base material for an electrophotographic lithographic printing original plate by using a certain ratio of synthetic rubber resin in combination with an acrylic resin emulsion, resulting in the present invention. It is.

An object of the present invention is to provide a base material for an electrophotographic printing plate that has improved water resistance, blister resistance, and printing durability against dampening water that enters from the end surface of the printing plate during printing.

The present invention is a base material for an electrophotographic lithographic printing original plate, which has a metal foil 2-layer paper as a base material, and an image-receiving layer containing a photoconductive substance is provided on the metal foil directly or through an intermediate layer. In this case, the adhesive between the metal foil and the paper consists of an acrylic resin emulsion and a synthetic rubber resin in a dry weight ratio of 50:50 to 9.
This is a base material for electrophotographic lithographic printing plate having a thickness of 1, characterized in that it is a mixture in a ratio of 7:3.

In the present invention, the metal foil has two roles: a conductive layer necessary for creating an image using electrophotography, and a water-resistant layer to prevent soaking water from reaching the paper layer during printing. The material may be any material as long as the metal is made into a thin film to meet this purpose. For example, it is a single composition of iron, hook, tin, aluminum, lead, zinc, etc., or an alloy thereof. Among the materials that can be laminated with paper, (1) it has a small specific gravity and is light;
(2) Good spreadability and easy processing into foil shape;
Although aluminum is preferred for these reasons, the present invention is of course not limited to this.

The intermediate layer refers to a layer provided between the metal foil of the base material (metal foil laminated paper) and the photosensitive layer (image receiving layer). Usually, a synthetic resin emulsion is mixed with clay, pigments such as calcium carbonate, conductive agents, waterproofing agents, etc., and then applied.

The image-receiving layer (photosensitive layer) refers to a layer that is imaged by electrophotography and contains a photosemiconductor as a basic component. Usually, an inorganic optical semiconductor powder such as zinc oxide, titanium dioxide, or cadmium sulfide dispersed in an insulating binder resin, or an organic optical semiconductor such as polyvinyl carbazole is used.

In the present invention, the acrylic resin emulsion is an emulsion obtained by finely pulverizing a homopolymerization or copolymerization of acrylic acid ester or methacrylic acid ester, or a copolymerization resin with vinyl acetate, acrylic acid, styrene, or the like.

In the present invention, it is a rubber synthesized using synthetic rubber resin, petroleum, and other raw materials, and depending on the raw material, styrene butadiene rubber (commonly known as 5BR), acrylonitrile butadiene rubber (J: NBR), methyl methacrylate butadiene rubber (i: MBR), butadiene rubber, isoprene rubber, butyl rubber, chloroprene rubber, silicone rubber, urethane rubber, fluorine rubber, etc.

The blending ratio of acrylic resin emulsion and synthetic rubber resin must be carefully determined as it directly affects the performance of the intended printing plate. Preferably, the ratio is in the range of 50:50 to 97:3. If the synthetic rubber resin exceeds this ratio, the adhesive 11 will be softened by intense heat during plate making, water vapor will be generated from the paper layer, and the air will suddenly evaporate.
It will not be able to withstand the carving and will be more likely to develop blisters.

On the other hand, if the synthetic rubber resin is less than this ratio, the effect of using the synthetic rubber resin in combination becomes almost negligible, and end face peeling during printing becomes more likely to occur.

If the amount of adhesive applied is extremely small, it will not be possible to achieve sufficient surface adhesion between the paper and the metal foil.

At least 0.5 fA, especially because one side of the lamination is paper and has a microscopically rough surface, and it is inevitable that some of the adhesive will penetrate into the paper waste.
r? A coating amount of the above amount is required.

If the amount applied is less than this, the paper surface will not be covered sufficiently with the laminating adhesive, and as a result, the adhesive strength between the metal foil and the paper will partially decrease. Then, water vapor is generated from within the paper layer when it is exposed to intense heat during the plate-making process.
Blisters form between the paper and the metal foil because they cannot withstand the rapid expansion of air.

The upper limit of the coating amount is naturally limited by the performance of the laminator or economic efficiency. Practically speaking, 1. OV Bakara 7.0
- is preferred, and is determined by taking into consideration the printing durability required when used as a printing plate.

The present invention will be specifically explained below using examples.

[Example 1] Aluminum foil with a thickness of 10 μm was laminated onto a commercially available high-quality paper with a weight of t100. The compounding ratio of the laminating adhesive was as follows, and the coating amount was 2.01/i. All "parts" below refer to weight ratios in terms of solid content.

(Composition I) Acrylic acid ester copolymer emulsion 80 parts (Hoechst Synthesis, Movinyl 987) Synthetic rubber resin 20 parts (Mitsui Toatsu, Polylac 750, SBR system) This aluminate paper was used as a base material and printed by the following method. A version was created.

First, a back coating layer with the following composition was provided on the side opposite to the aluminum. The amount of application is 2, OVr? It is.

Polyvinyl alcohol 30 parts (Nippon Gosei, T-33a) Vinyl acetate emulsion 50 parts (Hoechst Synthesis, Movinyl M-6go) Quaternary ammonium type conductive agent 20 parts (Dow Chemical,
ECR-77) Next, an intermediate layer was provided on the aluminum surface with the following composition. The amount of coating was 8 coats.

Clay 50 parts Acrylic acid ester copolymer emulsion 50 parts (Hoechst Synthesis, Movinyl DM772) Furthermore, a photoquadratic layer having the following composition was provided on the intermediate layer. Application amount is 22fA
? It is.

Zinc oxide 80 parts (
Sakai Chemical, Sazexna 2000) Acrylic resin 20 parts (Nippon Reichhold, 7-1021) Rose Bengal
0.1 part obtained sheet is 25
Dark adaptation was performed for 24 hours at 50% RH to obtain an electrophotographic printing original plate.

[Example 2] A printing original plate was obtained in exactly the same manner as in Example 1, except that the following composition (2) was used as a laminating adhesive.

(Composition ■) Acrylic acid ester copolymer emulsion 80 parts (Heggist Synthesis, Movinyl 987) Synthetic rubber resin 20 parts (Nippon Zeon, Hiker 1551, NBR type) 111) (Comparative Examples 1 to 3) For 2 min. A printing original plate was prepared in exactly the same manner as in Example 1, except that the composition of the adhesive, the amount of coating, etc. were changed as variables.

The evaluation results are summarized in the table.

(Evaluation method of original plate) The original plates obtained in the above Examples and Comparative Examples were plate-made using an Itic 175 type plate-making machine using a predetermined original drawing.

Next, the plate surface was thoroughly wetted with absorbent cotton impregnated with an etchant (manufactured by Itic Co., Ltd.), and printed using a Toko 800 type printing machine.

The dampening solution used during printing was a mixture of the above etchant and water in a ratio of 1:5. Gangu (Blackna 5500) was used as the printing ink.

The appearance of blisters during plate making depends on the preheating condition of a part of the heater in the plate making machine, the temperature of the heater, and the variable adjustment scale. The judgment was made by making a plate in a state exactly between the upper and lower limits.

As is clear from the above description, according to the present invention, there is no occurrence of blisters during plate making, and the water resistance to dampening water is also improved, so that the printing durability is greatly improved.

Claims (2)

[Claims] (1) An electrophotographic lithographic original plate comprising a paper base material on which metal foil is bonded with an adhesive, and an image-receiving layer containing a photoconductive substance provided on the metal foil directly or via an intermediate layer. In the base material, the adhesive binds the acrylic resin emulsion and the synthetic rubber resin at a dry weight ratio of '5'0!50.
From 97:. A base material for an electrophotographic lithographic printing original plate, characterized in that it is a mixture of 3. (2) Is the adhesive l15fA? The base material for an electrophotographic lithographic printing original plate according to claim 1, characterized in that the above coating is applied.