JPH0862881A - Electrophotographic planographic printing plate material - Google Patents

Abstract

PURPOSE: To provide a good electrophotographic planographic printing plate material having excellent dimensional stability with little toner fog in image. CONSTITUTION: This plate material consists of a supporting body, an intermediate layer formed on the one surface of the supporting body and containing a pigment, water-soluble resin or water-dispersed hydrophobic resin, and conducting agent as the main component, and a photoconductive layer containing a photoconductive pigment and an insulating resin as the main component formed on the intermediate layer. The intermediate layer also contains a conductive mica powder as the conducting agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic lithographic printing plate material, and more specifically, it relates to a high printing durability electrophotographic lithographic printing plate material having less toner fogging of images and excellent dimensional stability. It is a thing.

[0002]

2. Description of the Related Art In recent years, with the development of small offset printing machines and the development of automatic printing machines, the mainstream of light printing is shifting to offset printing. Many researches and developments have been made on such offset printing plate materials, and various materials have been put to practical use. Among these materials, the electrophotographic lithographic printing plate material having a photoconductive layer containing zinc oxide as a main component occupies the mainstream of light printing plate materials because it is inexpensive and the plate making process is simple. .

The electrophotographic lithographic printing plate is usually produced by corona charging, exposing to a desired pattern on the printing plate material using a plate making machine,
It is obtained by subjecting it to a development and fixing process to form a visible image of the desired pattern in the photoconductive layer. In the developing step, there are a dry developing method using a mixture of toner and a carrier such as iron powder, and a wet developing method using a developing solution in which the toner is dispersed in an organic solvent such as Isopar. When the plate is produced using the wet development method, there are advantages that the halftone reproducibility is good, the resolution is excellent, the time required for plate making is short, and no correction is required. For this reason, electrophotographic lithographic printing plates prepared by the wet development method are widely used in Japan.

In recent years, computers have been remarkably used in the printing industry, and the digital system is being replaced with the analog system. Electrophotographic planographic printing plate is 780
By blending a cyanine dye that sensitizes in the vicinity of nm, a so-called computer-to-plate method in which computer data is directly exposed to a plate material with a semiconductor laser beam has been used.

The electrophotographic lithographic printing plate material is used in addition to the image characteristics generally required as an electrophotographic copying material (for example, image density, toner fog, sharpness, image uniformity, printing background stain, etc.). Various characteristics required as a material (for example, the non-image portion of the printing plate that has undergone the development process can be desensitized, and the non-image portion can be made hydrophilic by the etching solution treatment of the photoconductive layer surface, And having excellent water resistance against a large amount of dampening water used during printing).

It has been proposed to form various intermediate layers between the support and the photoconductive layer in order to improve the toner fog and water resistance of the image as described above. JP 58-1
Japanese Patent No. 24695 proposes to use an aqueous dispersion type hydrophobic resin as a resin for obtaining water resistance in the intermediate layer and to form an intermediate layer containing carbon black for improving toner fogging. However, dispersion of hydrophobic carbon black requires the use of a large amount of surfactant, and as a result, the surfactant absorbs water during printing, resulting in poor water resistance and good dimensional stability. It was hard to get a peach.

Japanese Unexamined Patent Publication (Kokai) No. 56-24361 proposes to add conductive zinc oxide in order to improve toner fogging. However, in order to obtain an image without toner fog, it is necessary to increase the blending ratio of the conductive zinc oxide and bring the conductive zinc oxides into contact with each other, and the formed coating film has a porous structure, so that the water resistance is weak. However, a printing plate material having good dimensional stability could not be obtained.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-printing electrophotographic lithographic printing plate material having little toner fog on an image and excellent dimensional stability.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted various studies in order to solve the above problems, and as a result, by incorporating a conductive mica powder as a conductive agent into the intermediate layer,
The inventors have reached the present invention by finding out what can be achieved. That is, the electrophotographic lithographic printing plate material according to the present invention contains a support, a pigment formed on one surface of the support, a water-soluble resin or a water-dispersible hydrophobic resin, and a conductive agent as main components. An intermediate layer and a photoconductive layer containing a photoconductive pigment and an insulating resin as main components on the intermediate layer, wherein the intermediate layer contains a conductive mica powder as a conductive agent. It is a thing.

As the support used for forming the electrophotographic lithographic printing plate material of the present invention, paper, a laminated foil in which a metal foil such as aluminum or polyethylene is laminated on paper, or an inorganic pigment and a polyolefin are used. It can be selected from synthetic paper, which is a stretched void structure film having a thermoplastic resin as a main component. Generally, those having a thickness of 100 to 168 μm are preferable.

When the intermediate layer in the present invention is formed of only the water-dispersible hydrophobic resin and the pigment, the water resistance is improved and the dimensional stability can be improved, but the intermediate layer has high electric resistance and light attenuation. As a result, the toner fogging of the image was large and a good image could not be obtained. In order to obtain a good image with less toner fog, the surface electric resistance value of the intermediate layer is 1.0 × 10 ⁷ Ω / □ to 1.0 × 10.
^A reasonable value is ¹¹ Ω / □. Then, when the conductive mica powder was contained in the intermediate layer, the electric resistance could be made a target value without impairing the water resistance.

The conductive mica powder is a mica powder whose surface is coated with a conductive substance such as metal oxide or carbon.
The conductive mica powder has a scale-like shape due to the shape of the mica powder as the mother's womb, and the barrier property of the intermediate layer coating film is remarkably improved and the water resistance is improved. Further, since it is scale-like, it has an advantage that the electric resistance can be lowered by a small amount of compounding as compared with conductive zinc oxide or the like, and it is an optimal material for the present invention.

The content of the conductive mica powder is 5 to 70% by weight, preferably 10 to 50% by weight based on the weight of the solid coating material in the intermediate layer. If it is less than 5% by weight, the electric resistance will not be sufficiently lowered, and the object of the present invention will not always be met. When the amount is more than 70% by weight, the electric resistance of the intermediate layer becomes too low, so that snow occurs in the solid part of the plate-making product and the image uniformity deteriorates. As the pigment that can be used in the intermediate layer of the present invention, for example, calcium carbonate, magnesium carbonate,
Kaolin, talc, calcined clay, silica, diatomaceous earth,
Inorganic pigments such as mica, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, and barium sulfate, as well as organic resin fine powders such as urea-formalin resin, styrene-methacrylic acid copolymer, and polystyrene resin Can be mentioned. It is preferable to use the pigment in an amount of 70% by weight or less based on the weight of the solid coating material in the intermediate layer.

As the resin used for the intermediate layer of the present invention,
A water-dispersible hydrophobic resin and / or a water-soluble resin can be used. The resin content is preferably 30 to 90% by weight based on the weight of the solid content of the coating material in the intermediate layer. However, if a large amount of a water-soluble resin is blended, the water resistance will decrease and it will not be possible to obtain a printing plate material with good dimensional stability. Therefore, the water-soluble resin content is preferably 5% by weight or less.

Examples of the water-dispersible hydrophobic resin used in the intermediate layer of the present invention include styrene-butadiene latex, acrylic emulsion, vinyl acetate-acrylic acid ester copolymer emulsion, polyurethane emulsion, polyvinyl chloride emulsion, and poly (vinyl chloride) emulsion. Examples thereof include a vinylidene chloride emulsion, a methacrylic acid ester copolymer emulsion, and an acrylic acid ester copolymer emulsion. Of course, it is not limited to these. Examples of the water-soluble resin include polyvinyl alcohol, oxidized starch, modified starch, gum arabic, gelatin, casein, chitosan, methyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid salt, polyacrylic amide, and styrene-maleic anhydride. Acid copolymer salt, methyl vinyl ether-maleic anhydride copolymer salt, methyl vinyl ether-maleic anhydride copolymer, isopropylene-
A maleic anhydride copolymer salt or the like can be used. Of course, it is not limited to these.

Further, in order to improve the water resistance, it is preferable to provide these resins with a reactive group that participates in a crosslinking reaction, such as a hydroxy ester of α / β-unsaturated carboxylic acid, an α / β-unsaturated amide or Glycidyl (meta)
A small amount of widely known reactive monomers such as acrylate, N-methylol acrylamide, monomers having two or more double bonds (diallyl phthalate, allyl glycidyl ether), and 3-chloro-2-hydroxypropyl methacrylate are copolymerized. Those that are preferable.

If necessary, auxiliary additives such as a dispersant and a water-proofing agent for strengthening water resistance may be added to the intermediate layer. As the water resistance agent, for example, glyoxal, glutaraldehyde, expensive aldehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds,
A polyamide resin, a diglycidyl compound such as glycerin diglycidyl ether, a dimethylolurea compound, and an inorganic compound such as ammonium persulfate, ferric chloride, and magnesium chloride, boric acid, or borax can be used. Of course, it is not limited to these.

In the present invention, the intermediate layer is formed by coating one surface of the support with an aqueous coating material containing the above-mentioned material, and drying and solidifying the coating layer to form a film. At this time, preferably, drying at a temperature of 80 to 150 ° C. can form a water resistant intermediate layer. The weight of the intermediate layer is 3 to 30.
It is preferably in the range of g / m ² . The method of applying the intermediate layer paint is the Meyer bar method, the 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 photoconductive layer of the present invention is formed by applying a coating material comprising zinc oxide, titanium oxide or the like as a photoconductive pigment, a resin, a sensitizing dye, and a solvent on the intermediate layer and drying.
The dry weight of the photoconductive layer is preferably in the range of ^{20 to} 30 g / m ² . When the amount is less than 20 g / m ² , the image density is low, and when the amount is more than 30 g / m ² , the charging potential reaches saturation, which is meaningless because the image density is not improved and the cost is increased. As the method for applying the photoconductive layer coating material, the same method as for the intermediate layer can be used.

The resin used in the photoconductive layer of the present invention is generally an acrylic acid ester copolymer having good hydrophilicity,
Examples thereof include methacrylic acid ester copolymers, vinyl acetate copolymers, silicone resins and butyral resins. There is no problem with copolymerizing a monomer having a functional group such as acrylic acid, methacrylic acid or maleic acid with these resins for the purpose of improving image quality and the like.
The resin contained in the photoconductive layer is preferably 10 to 30% by weight with respect to the photoconductive pigment in the paint, and 15 to 20% by weight.
Is more preferably within the range.

As the sensitizing dye used in the photoconductive layer of the present invention, for example, rose bengal, uranine, BPB (bromphenol blue), nigrosine and the like, which have been conventionally used, photosensitive paints, electron accepting substances, and Wavelength of 700-
Various sensitizers such as compounds having maximum sensitivity to light rays in the range of 1000 nm are used. If necessary, an auxiliary additive component such as a sensitization aid may be added to the photoconductive layer of the present invention. Examples of the sensitization aid include maleic anhydride, phthalic anhydride, cobalt salt, manganese salt and the like.

In the present invention, a back layer can be formed on the surface opposite to the photoconductive layer for the purpose of preventing the penetration of toner during plate making. Such a back layer is made of pigment, resin, or the like. In 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 pigment, resin, dispersant, and waterproofing agent used in the back layer of the present invention are, for example,
The same as the intermediate layer can be used.

The resin used for the back layer of the present invention may be the same as that for the intermediate layer. As the conductive agent used in the back layer of the present invention, for example, polyvinylbenzyl trimethyl ammonium chloride, polydimethyl diallyl ammonium chloride, cationic conductive resin such as styrene acrylic acid trimethylaminoethyl chloride copolymer, polystyrene sulfonate, Examples thereof include anionic conductive resins such as polyacrylic acid salts and polyvinyl sulfonate, carbon black, synthetic hectorite, conductive whiskers, and conductive mica powder.

The weight of the back layer after drying is 5 to 30 g /
It is preferably within the range of m ² . More preferably 1
It is preferably 0 to 20 g / m ² . If it is less than 5 g / m ^2, the penetration of the wet toner cannot be sufficiently prevented during plate making, and 3
If it is more than 0 g / m ² , curl to the back side becomes too large. As a method for applying the back layer coating material, the same method as for the intermediate layer can be used. The electrophotographic lithographic printing plate material having the intermediate layer obtained as described above has little toner fog in the image and is excellent in dimensional stability, and it was possible to provide a very excellent printing plate material. .

[0025]

[Example]
The present invention will be described more specifically by way of examples, but of course,
The present invention is not limited to this. Each implementation
In the examples, "part" means "dry weight part". Example 1 An electrophotographic lithographic printing plate was prepared in the following manner and
The sex was evaluated. (1) Basis weight 100g / m² Table of support made of paper
A barrier layer of the following composition is applied to the surface by size / press treatment.
2 g / m² It was formed with a dry coating amount of. (Size / press composition) Polyvinyl alcohol 80 parts Sodium polyacrylate 20 parts (2) Next, the following on the surface of the size / press treated base paper:
15 g / m of coating liquid for intermediate layer ² Apply so that the dry weight of
did. Further, the surface electric resistance of the intermediate layer is 50% RH, 25
It measured in the atmosphere of (degree C). The results are shown in Table 1. (Intermediate layer coating liquid) Conductive mica powder (trademark: W-MF, manufactured by Mitsubishi Materials) 10 parts Kaolinite clay (trademark: Hydrogloss 90, manufactured by Huber) 65 parts Acrylic emulsion (trademark: A-104, manufactured by Toagosei) ) 10 parts Urethane emulsion (trademark: Vylok RL-3, manufactured by Kanebo NSC) 20 parts (3) Furthermore, 25 g of the following photoconductive layer coating liquid is applied to this surface.
/ M² The dry weight of (Photoconductive layer coating liquid) Photoconductive zinc oxide (trademark: Sazex 2000, manufactured by Sakai Chemical) 100 parts Silicon resin (trademark: KR-211, manufactured by Shin-Etsu Chemical) 17 parts Rose Bengal 0.1 part (4) The support Apply the following back layer coating solution on the back of the body.
g / m² The dry weight of (Back layer liquid) Polyvinyl alcohol (Trademark: T-330, manufactured by Nippon Synthetic Chemical Industry) 30 parts Vinyl acetate resin (Trademark: Sebian A-522, manufactured by Daicel) 50 parts Quaternary ammonium type conductive agent (trademark Chemistat 5500, Sanyo Kasei) Made) 20 parts

50% of the printing plate obtained as described above
After acclimatization for 24 hours in a dark place having an atmosphere of RH and 25 ° C., the plate was made with an ITEC 275 type electronic plate making machine, and the toner fogging of the image quality was examined. This was treated with an etchant (product of Aitec Co., Ltd.) as a desensitizing resin and printed with an offset printing machine (Hamaduster 500). Table 1 shows the obtained results.

[0027]

Example 2 An electrophotographic lithographic printing plate was prepared in the same manner as in Example 1 except that the coating composition for the intermediate layer was changed to the following composition, and evaluated. The results are shown in Table 1. (Intermediate layer coating liquid) Conductive mica powder (trademark: W-MF, manufactured by Mitsubishi Materials) 45 parts Kaolinite clay (trademark: Hydrogloss 90, manufactured by Huber) 25 parts Acrylic emulsion (trademark: A-104, manufactured by Toagosei) ) 10 parts Urethane emulsion (trademark: Vylok RL-3, manufactured by Kanebo NSC) 20 parts

Example 3 An electrophotographic lithographic printing plate was prepared in the same manner as in Example 1 except that the coating solution for the intermediate layer was changed to the following composition, and evaluated. The results are shown in Table 1. (Intermediate layer coating liquid) Conductive mica powder (trademark: W-MF, manufactured by Mitsubishi Materials) 60 parts Acrylic emulsion (trademark: A-104, manufactured by Toagosei) 10 parts Urethane emulsion (trademark: Vylok RL-3, Kanebo NSC) Made) 20 parts

Comparative Example 1 An electrophotographic lithographic printing plate was prepared and evaluated by the same treatment as in Example 1 except that the coating composition for the intermediate layer was changed to the following composition. The results are shown in Table 1. (Intermediate layer coating liquid) Kaolinite clay (trademark: Hydrogloss 90, manufactured by Huber) 70 parts Acrylic emulsion (trademark: A-104, manufactured by Toagosei) 10 parts Urethane emulsion (trademark: Vylok RL-3, manufactured by Kanebo NSC) 20 copies

Comparative Example 2 An electrophotographic lithographic printing plate was prepared by the same treatment as in Example 1 except that the coating composition for the intermediate layer was changed to the following composition. The results are shown in Table 1. (Intermediate layer coating liquid) Carbon black aqueous dispersion (trademark: LKB-100, manufactured by Hoechst Synthetic) 5 parts Kaolinite clay (trademark: Hydrogloss 90, manufactured by Huber) 65 parts Acrylic emulsion (trademark: A-104, Toagosei) Made) 10 parts Urethane emulsion (trademark: Vylok RL-3, Kanebo NSC) 20 parts

[0032]

[Table 1]

[0033]

Industrial Applicability According to the present invention, it is possible to produce an electrophotographic lithographic printing plate material having no toner fog, good dimensional stability and excellent image quality, which is extremely useful industrially. .

Claims (1)

[Claims] 1. A support, an intermediate layer formed on one surface of the support, and containing a pigment, a water-soluble resin or a water-dispersible hydrophobic resin, and a conductive agent as main components, and an intermediate layer on the intermediate layer. An electrophotographic lithographic printing plate material comprising a photoconductive layer containing a photoconductive pigment and an insulating resin as main components, and the intermediate layer containing conductive mica powder as a conductive agent.