JPH05313422A - Making method for electrophotographic lithographic printing plate - Google Patents

Abstract

PURPOSE:To provide an electrophotographic lithographic printing original plate making method for preventing the sticking of toner on the side edge surfaces of an electrophotographic lithographic printing original plate, thereby evading soiling in printing caused by the sticking of the toner. CONSTITUTION:In this electrophotographic lithographic printing plate making method by which a printing plate is obtained by forming a toner image by an electrophotographic method, on the electrophotographic lithographic printing original plate 1 provided with a photoconductive layer on a conductive supporting body and, at least, charge holding layers 4 on the side edge surfaces 5 of the photoconductive layer, and then removing at least a nonimage part photoconductive layer other than a toner image part, a space corresponding to at least the thickness of the printing original plate from the sides of the charge holding layers 4 on the side edge surfaces of the printing original plates and the rear surface of the conductive supporting body is held in an insulating atmosphere to electrify the electrophotographic lithographic printing original plate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a toner image by an electrophotographic method on an electrophotographic lithographic printing plate precursor having a photoconductive layer on a conductive support and at least a charge holding layer on its side end surface. Then, at least regarding the plate making method of the electrophotographic lithographic printing plate by removing the non-image area photoconductive layer other than the toner image area to obtain a printing plate, by preventing adhesion of toner on the end surface of the electrophotographic lithographic printing plate side, The present invention relates to a method for making an electrophotographic lithographic printing plate that avoids printing stains caused by it.

[0002]

2. Description of the Related Art In recent years, with the establishment of mechanical image processing technology and storage and transmission technology for large-capacity data, image input / correction / editing / layout of characters and figures, page layout, etc. are all controlled by a computer to enable high-speed communication. An electronic editing system is in operation that can instantly output to a terminal plotter at a remote place through a network or satellite communication. In particular, in the field of newspaper printing, which is based on the idea of immediacy, the demand for this electronic editing system is high.

However, the lithographic printing plate called PS plate, which has been conventionally used in the newspaper printing field, is
Since image formation involves a chemical structure change due to actinic rays of the photosensitive layer, the sensitivity is generally low, and a silver salt photographic film original plate on which an image is recorded in advance is contact-exposed to perform plate making. Therefore, even in the place where the electronic editing system is in operation, the image output is once performed on the silver salt photographic film, and based on this, the printing plate is indirectly produced by contact exposure to the PS plate. .. This is the light source of the output plotter (eg H
It is difficult to develop a direct-type printing plate that has high sensitivity to produce a printing plate in a practical time with an e-Ne laser, semiconductor laser, etc., and that is easy to handle in a bright room. It is due.

Therefore, an electrophotographic lithographic printing plate is considered as a lithographic printing plate having a high photosensitivity which can provide a direct type printing plate. Conventional printing plate materials utilizing electrophotography include, for example, Japanese Examined Patent Publication Nos. 47-47610 and 48-183.
No. 25, No. 48-40002, No. 51-15766, etc., and photoconductive zinc oxide / resin-dispersed printing plate materials, and Japanese Patent Publication Nos. 37-17162 and 38-7758.
No. 41-2426, No. 46-39405, JP-A No. 50-19509, No. 52-2437, and No. 54-.
No. 134632, No. 54-145538, No. 55-1
There are known non-image area eluting type printing plate materials having an organic photoconductive compound / binder resin photoconductive layer described in JP-A-53948 and JP-A-57-147656.

The former photoconductive zinc oxide / resin-dispersed printing plate material has a zinc oxide-rich photoconductive layer with a paper having water resistance and conductivity as a support, and forms a toner image by electrophotography. After that, the non-image area is wetted with a desensitizing treatment liquid (for example, an acidic aqueous solution containing a hexacyanoiron salt or an inositol hexaphosphate) in order to render it non-sensitized, and then subjected to printing. The printing plate treated in this manner has a maximum number of printable sheets of about 10,000 from the viewpoint of good printed image reproducibility, and has a drawback that the composition with enhanced desensitization deteriorates the image quality. is doing.

On the other hand, in the latter non-image area eluting type printing plate material, since these electrophotographic photoconductive layers are generally provided on the aluminum support whose surface is hydrophilized,
If the adhesion between the support and the photoconductive layer is strong, P is essentially
It has printing durability equivalent to or better than S plate. Also, already 80
Organic photoconductive compounds having a practical sensitivity of 0 nm or more are known, and scanning exposure type printing plate materials using these compounds in the photoconductive layer have been put to practical use.

In these non-image area eluting type electrophotographic lithographic printing plates, it is necessary to remove the non-image area to expose the hydrophilic surface, and the general plate-making method is electrophotography having a photoconductive layer. A well-known electrophotographic image forming method for a lithographic printing plate precursor, that is, a photoconductive layer is charged substantially uniformly in a dark place, and then an electrostatic latent image is formed by imagewise exposure, followed by toner development and fixing. After the toner image is formed by, the non-image area other than the toner image area is treated with a solution containing a photoconductive layer dissolving agent such as an alkali agent to dissolve and remove the non-image area photoconductive layer from the plate ( It is so-called elution) and the plate is made.

When printing is carried out using the electrophotographic printing plate thus obtained, it is possible to print on an ink receiving material smaller than the size of the printing plate by an ordinary sheet-fed printing machine or to use an ink receiving material larger than the printing plate. Even if there is a final cut to a size smaller than the printing plate, for example, on the printing plate side end surface (the surface of the printing plate end that is not used for holding the printing machine), the image part Similarly, even if ink adheres, there is no problem as a result, but it is printed on a paper larger than the size of the printing plate, and at the same time, the final product without cutting the inside of the printing part corresponding to the plate side end face In this case, as a result, a print stain is generated in a portion corresponding to the end face of the printing plate, and this stain is remarkable when toner development is performed by the reversal development method.

The reversal developing method is a method which makes a pair with the normal developing which is the most commonly used developing method. The image forming portion is made to have a low electric potential and toner having the same sign as the charge polarity of the charging surface is used. Substantially developing is performed under application of a developing bias voltage. At that time, the toner receives the Coulomb repulsion force of the non-image portion and adheres to the image forming portion, which is a low-electricity portion, according to the lines of electric force. Therefore, in the reversal development, a good image with less fog and image fineness can be obtained, which is particularly useful in a printing-related field where high resolution and high quality image reproducibility are required. When the reversal development is performed, the above-mentioned print stain becomes apparent, because at least the end surface of the conductive support cannot retain electric charge, resulting in toner adhesion, and in printing, the toner adhered to the side end surface becomes an ink receiving portion. This is because.

Therefore, in order to prevent the printing stains on the side end faces of the printing plate obtained by reversal development of the electrophotographic lithographic printing plate precursor, the first method is disclosed in JP-A-63-17824.
In JP-A-0, it is proposed to coat an insulating resin layer on the end surface of the electrophotographic lithographic printing plate side. In other words, we think that the cause of the printing stain on the printing plate side end surface is that the side end surface does not have the ability to retain electric charge, so by providing an insulating resin layer on the side end surface, we will hold the charging potential and prevent toner adhesion. It is what Further, this method is further advanced, and the method is disclosed in JP-A-4-421.
Japanese Laid-Open Patent Publication No. 64 discloses a printing original plate for electrophotographic plate-making in which a layer containing a polysiloxane polymer is provided on a side end surface to prevent toner from being positively attached.

A second method is disclosed in Japanese Patent Laid-Open No. 2-616.
No. 54, No. 2-66566, No. 4-22972, etc., a toner development of a hydrophilic polymer, an alkali-soluble substance, or an alkali metal silicate or the like on the end surface of the electrophotographic lithographic printing plate precursor. By providing a coating layer that can be removed in the processing steps after fixing and even if the toner adheres to the side edge surface during toner development, by removing the toner together with this coating layer in the subsequent step, printing stains can be prevented. thing. Furthermore, as a third method, as described in JP-A-4-51253, a method of desensitizing the end surface of the electrophotographic lithographic printing plate side after toner development, or as described in JP-A-4-53967.
A method has also been proposed in which an eluate component is applied to the side end surface and its peripheral portion after the toner development and before the elution treatment.

When the above-mentioned coating layer is provided, the coating liquid may actually spread to not only the upper end surface but also the upper end portion of the photoconductive layer and the back surface of the support, and these methods are applied to the end surface on the electrophotographic lithographic printing plate side. Even if it is taken, basically, in the case of reversal development, the toner is forcibly electrodeposited at a portion having a lower potential than the bias voltage applied from the developing electrode. In the third method in which the holding layer is not provided on the side end face, not only on the coating layer or the end portion of the support, but also at the boundary portion between the photoconductive layer and the coating layer or the support by the edge effect The toner adheres within a certain width.
As a result, in particular, the photoconductive layer at the boundary portion is not completely removed by the elution treatment due to the resist by the toner, and the printing stains on the side end faces are generated in all the printing plates having these side end faces subjected to these treatments. It couldn't be prevented. On the other hand, with the first method, as a result, the insulating resin layer may remain on the side end faces, causing print stains.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a toner image is formed by an electrophotographic method on an electrophotographic lithographic printing plate precursor in which a photoconductive layer is provided on a conductive support and at least a charge holding layer is provided on a side end surface thereof. In the plate making method of an electrophotographic lithographic printing plate, a non-image part photoconductive layer other than the toner image part is removed to form a printing plate, which is often observed when the electrophotographic lithographic printing plate precursor is subjected to reversal development. An object of the present invention is to provide a method for making an electrophotographic lithographic printing plate that avoids printing stains corresponding to the end surface of the printing original plate side. More specifically, a method for making an electrophotographic lithographic printing plate that avoids printing stains due to the charge holding layer on which toner adheres due to poor charging or poor charge holding of the charge holding layer on the printing original plate side forms an ink receiving portion. To provide.

[0014]

As a result of repeated studies to solve the above problems, an electrophotographic lithographic printing plate precursor having a photoconductive layer provided on a conductive support and at least a charge holding layer on its side end face is obtained. In the plate making method of the electrophotographic planographic printing plate, a toner image is formed by an electrophotographic method, and then at least the non-image area photoconductive layer other than the toner image area is removed to obtain a printing plate. This was achieved by charging the electrophotographic lithographic printing original plate while maintaining at least a space corresponding to the thickness of the original printing plate from the side formed by the back surface of the electrophotographic support in an insulating atmosphere.

When the mechanism of remaining of the charge retention layer was examined again, the most common electrification of the electrophotographic lithographic printing plate precursor was carried out by closely holding it on a conductive surface plate made of aluminum or cast iron. Even if the electrophotographic lithographic printing plate precursor provided with the charge retention layer is to be charged, the charge current predominantly flows to the conductive member (e.g., a platen) near the printing plate side end face from the beginning or is applied to the printing plate side end face. The charge applied to the surface of the charge retentive layer is transferred to the surface of the charge retentive layer conductive member contact portion or the back surface of the conductive support near the side end face and leaks to the surface plate. It was found that the toner could adhere because the potential could not be maintained.

Therefore, in the present invention, when the electrophotographic lithographic printing original plate having at least the charge holding layer on the support side end surface is subjected to reversal development, at least printing is performed from the side formed by the printing original plate side end surface and the conductive support back surface. By holding a space equivalent to the thickness of the original plate in an insulating atmosphere and charging it, it becomes possible to carry out development by holding the charges on the surface of the side end surface charge holding layer, and suppress the occurrence of toner fog on the charge holding layer. By preventing the formation of the end face ink receiving section, it became possible to perform printing without the occurrence of printing stains on the side end faces.

The occurrence of print stains due to the remaining charge retentive layer after elution is described in JP-A-4-22972 and JP-A-4-4216.
As a means for solving the problem already raised in Japanese Patent Laid-Open No. 4 publication, the remaining at the end face of the insulating resin layer (remaining at the side end face of the charge retention layer in the present invention) is solved by the insulating resin. A printing original plate improved by changing the composition of the layer to a specific hydrophilic resin layer and an original printing plate having an ink-repellent polysiloxane polymer-containing layer are disclosed. However, this method does not substantially improve the toner adhesion by reversal development, and the toner adheres to the polysiloxane polymer-containing layer to a similar extent to some extent, and the toner peels off at least in the initial stage of printing. However, the printing stains were caused, but it became difficult for the toner to land on the portions coated with the charge retention resin by the plate making method of the present invention, and the printing stains were substantially eliminated.

The present invention will be described in detail below. The charge retention layer provided on the end surface of the electrophotographic lithographic printing plate precursor according to the present invention is a reagent that accepts a charge by corona charging, is soluble in the eluent composition described later, and can be removed by the end of plate making at the latest. It is desirable that the reagent is composed of a reagent that is more easily solubilized than the electrophotographic photoconductive layer, or is composed of at least a reagent having a charging property and an ink repelling property.

Of the reagents for forming the charge retention layer, specific examples of the former (eluting type reagent) include styrene / maleic anhydride copolymers and styrene / maleic acid monomonomers described in JP-A-63-178240. Ester copolymer, methacrylic acid / methacrylic acid ester copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer, acrylic acid /
Styrene, methacrylic acid ester, acrylic acid such as methacrylic acid ester copolymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, vinyl acetate / crotonic acid / methacrylic acid ester copolymer Copolymers of esters, vinyl acetate, vinyl benzoate and the like with acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid and other carboxylic acid containing monomers or acid anhydride group containing monomers Vinyl acetal resins such as copolymers containing monomers having methacrylic acid amide, phenolic hydroxyl group, sulfonic acid group, sulfonamide group, sulfonimide group, phenol resin, partially saponified vinyl acetate resin, xylene resin, polyvinyl butyral, etc. Is mentioned.

Examples of the latter (ink repellent agent) include organosiloxane polymers containing various organopolysiloxanes described in JP-A-4-42164. These organosiloxane polymers are generally inferior in adhesive strength to a metal support such as aluminum. Therefore, particularly when they are used as the charge retention layer according to the present invention, at least prior to coating these charge retention layers. It is preferable to provide a known primer layer made of a silicone coupling agent or the like.

Among these agents, the former monomer-containing copolymer having a carboxyl group and the phenol resin are particularly excellent in charge retention and film forming property, and therefore can be advantageously used. As the monomer-containing copolymer having a carboxyl group, a copolymer of styrene and maleic acid monoester, a binary copolymer of acrylic acid or methacrylic acid and their alkyl, aryl, or aralkyl ester may be used. preferable. Further, a copolymer of vinyl acetate or vinyl benzoate and crotonic acid is also preferable. Among the phenol resins, particularly preferable are phenol,
A novolak resin obtained by condensing o-cresol, m-cresol, or p-cresol with methanal or ethanal under acidic conditions can be mentioned. These resins alone,
Alternatively, two or more kinds may be mixed and used.

In order to improve the coating property and the adhesion by smoothing the surface of the charge retaining layer, and to facilitate the removal of the charge retaining layer if the charge retaining layer is an elution type, the charge retaining layer is The lower layer, that is, the intermediate layer between the end surface on the support side and the charge retentive layer may be provided with a hydrophilic coating layer described in JP-A-2-61654, 4-22972, or the like. A charge retention layer may be laminated on the easily alkali-soluble resin described in Japanese Patent No. 66566. In particular, printing stains can be further improved by providing a hydrophilic coating layer below the support-side end surface charge retention layer, or even by providing a coating layer containing a hydrophilic inorganic substance such as an eluent component, separately. Furthermore, polystyrene, nylon, polymethylmethacrylate,
By coexisting an appropriate amount of organic polymer fine particles such as polyurethane, it is possible to improve the film formability without significantly affecting the electric charge.

The charge retention layer according to the present invention may be applied in the form of a coating liquid by a conventionally known method such as coating with a brush, sponge, non-woven fabric, or roller, or spray coating. Solvents for the coating liquid include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane and chloroform, alcohols such as methanol, ethanol, 2-propanol, 1-butanol and propanediol, 2-butanone, 4-methyl-2-pentanone, cyclohexanone and other ketones,
Examples thereof include glycol ethers such as 2-methoxyethanol and 2-methoxyethyl acetate, cyclic ethers such as oxolane, oxane and dioxane, and fatty acid alkyl esters such as ethyl acetate, propyl acetate, butyl acetate and ethyl lactate. These solvents may be used alone or in combination of two or more.

In order to improve the coatability and the adhesiveness to the support, it is preferable to add various surfactants when preparing the coating solution. Examples of such a surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, glycerin fatty acid ester, and acetylene. Nonionic surfactants such as diols and polyoxyethylene-added acetylene diols, fatty acid salts, hydroxyalkanesulfonates, dialkylsulfosuccinates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenoxypolyoxyethylenepropylsulfone Acid salts, polyoxyethylene alkylsulfophenyl ether salts, N-alkylsulfosuccinic acid monoamide salts, Oil sulfonates, fatty acid alkyl ester sulfate ester salts, alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts, polyoxyethylene alkylphenyl ether sulfate ester salts, fatty acid monoglyceride sulfate ester salts, alkyl phosphate ester salts, poly Anionic interfaces such as oxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified styrene / maleic anhydride copolymers, partially saponified olefin / maleic anhydride copolymers Activators, alkylamine salts, quaternary ammonium salts, cationic surfactants such as polyoxyethylene alkylamine salts, polyoxyethylene polyamine derivatives, carboxybetaines Aminocarboxylic acid salts, sulfobetaines, amino sulfate esters, amphoteric surfactants such as imidazolines.

Among the above surfactants, anionic surfactants and nonionic surfactants are particularly effective. These surfactants can be used alone or in combination of two or more kinds. The amount of these surfactants used is not particularly limited, but its preferred range is 0.0 in the coating liquid.
It is used in the range of 01 to 5% by weight, more preferably 0.01 to 2% by weight.

In the charge holding layer according to the present invention, at the time of reversal development of the electrophotographic lithographic printing plate precursor, at least a side end face must hold a constant charging potential to suppress toner fog. Therefore, the charge retention layer is applied so that it is charged to a high potential, more preferably to a potential equivalent to the charging potential of the electrophotographic photoconductive layer, by the bias voltage at the minimum during reversal development regardless of the applied reagent. It is essential. In particular, when the charge retention layer is an elution type, the coating amount is the maximum amount at which the charge retention layer is completely removed at least during the elution treatment, and it is desirable to adjust the amount so as not to exceed the amount. The chargeability, etc. cannot be specified unconditionally because it varies depending on the agent used for the charge retention layer, but the recommended general solid coating amount is 0.2 to 6.5 g / m ² , and more preferably 1 Is in the range of up to 5 g / m ² .

The side end faces to be coated differ depending on the usage of the printing plate. When only a pair of end faces of the printing original plate facing each other are printing faces, such as newspaper printing, one end face (side end face) to be used for printing. ), It is desirable to apply it on all four end faces in consideration of various usage forms. The coating may be carried out for each plate or in a state in which a large number of sheets are laminated, but in any case, care must be taken to ensure a uniform film thickness. .. Especially in the latter case, Japanese Patent Publication No. 57-2325
No. 9, as described in JP-A-57-99647,
It may be applied with the interleaving paper sandwiched therebetween. In any of the coating methods, it is important to prevent the coating liquid from flowing into the surface of the printing original plate and the back surface of the support. In particular, if the ink repellent charge retaining layer is of a type that is not removed in the post-treatment process after toner development including elution, when it is formed on the photoconductive layer, it acts like a toner and retains the charge. Special attention is required because the photoconductive layer below the layer may be less likely to be eluted and an ink receiving portion may be formed.

The electrophotographic lithographic printing plate precursor having the above charge holding layer on the side end surface thereof maintains an insulating atmosphere at least a space corresponding to the thickness of the printing plate precursor from the side formed by the end surface of the printing plate and the back surface of the conductive support. , Charge the electrophotographic lithographic printing plate precursor. As a charging means, conventionally, a non-contact charging method such as a corotron method and a scorotron method, and a contact charging method such as a conductive brush charging and a conductive roller charging are known, and at least a charge holding layer and an electrophotographic photoconductive layer according to the present invention are known. Any method may be used as long as the layer can be uniformly charged and the potential of a certain degree or more can be secured without deterioration of the photoconductive layer.
The corotron method is advantageously used because of its simple structure, charging efficiency, and maintainability.

Charging of the electrophotographic lithographic printing plate precursor is carried out by moving at least one of the charging means and the printing plate precursor. When moving the printing original plate, a method of using a belt passed in the moving direction, a method of sandwiching the roll pair, a method of using a plurality of rolls passed at right angles to the moving direction, a method of holding and moving the platen, and the like, and A combination of these methods can be adopted, but the platen holding and moving method, which does not change the gap between the charging means during charging and the charging surface of the printing original plate and the transfer moving speed, and is non-contact with all the charged surfaces, is most advantageously used. To be done. Particularly in the platen holding and moving method, it is desirable to provide a vacuum adsorption mechanism on the platen to charge the printing original plate while adsorbing it on the platen.

In the present invention, at the time of charging, at least a space corresponding to the thickness of the printing original plate from the side formed by the end surface of the printing original plate and the back surface of the conductive support is maintained in an insulating atmosphere for charging. As the method of charging in the insulating atmosphere in the present invention, at least the printing plate side end surface and the vicinity of the side end surface are held in air to be charged in a non-contact state, and the back surface of the conductive support near the side end surface. And a method of charging by charging and holding an insulating member in contact with the insulating member. When charging using the platen holding and moving method, the former non-contact charging method uses a platen whose width is shorter than the width of the printing original plate (plate length in the direction perpendicular to the printing direction), and both end faces of the printing plate are The method of holding and charging in a state of protruding from the surface of the surface of the surface plate corresponding to the back surface of the conductive support in the vicinity of the side end surface, while at least floating the conductive support in the vicinity of the side end surface. A method of charging may be mentioned. Also, in the insulating member contact holding charging method, an insulating member is fitted on at least the upper surface of the surface plate corresponding to the back surface of the conductive support near the side end surface, and the back surface of the conductive support near the side end surface is in contact therewith. A method of charging so that it is held may be mentioned.

Particularly in the latter case, for general printing, such as newspaper printing, in which a certain printing plate size cannot be specified, the conductive member is exposed only at the central portion in the moving direction of the surface plate so that the earth can be grounded. It is possible to deal with this by disposing at least the end surface of the printing original plate side so that it does not come into contact with it. Also in the former case, a platen structure may be provided so that the air discharge position can be adjusted so that the end surface of the printing original plate side does not contact the platen. In any case, the distance between the printing plate side end surface and the conductive member, especially the platen conductive portion which is not covered by the printing plate with respect to the corona charging means, is important, and at the time of charging, the shortest distance is at least electrophotography. The thickness of the conductive support used for the lithographic printing original plate is not less than the thickness, more preferably not less than 5 times, and further preferably not less than 20 times the thickness.
It is necessary to interpose an insulating member including air within a range that does not affect the charging conditions (particularly the gap between the charging unit and the charging surface of the printing original plate). Considering the size of the printing original plate and the wraparound of the charge retentive layer to the back surface of the support, it is preferable to dispose the insulating member in a large size within a range in which the conductive support can be substantially grounded during charging. ..

As the insulating member used in the present invention,
Polyethylene, polypropylene, methylpentene resin (TPX), vinyl chloride resin, acrylic resin, styrene resin, ABS resin, acetal resin, fluororesin (Teflon etc.), polyamide resin, polyester resin, phenol resin, xylene resin, alkyd resin, epoxy Resins, urea resins, melamine resins and other synthetic resins, chloroprene rubber, ethylene propylene rubber, butyl rubber, epichlorohydrin rubber, silicone rubber, fluororubber, chlorosulfonated polyethylene rubber and other rubbers, natural and synthetic excluding mica groups ( Minerals (including resin binding type molded articles), ceramics, and the like.

The electrophotographic lithographic printing plate precursor according to the present invention comprises
A photoconductive layer is provided on a conductive support, and a toner image can be formed by an ordinary electrophotographic development method.
The conductive support used in the electrophotographic lithographic printing plate precursor is a plastic sheet having a conductive surface, solvent-impermeable and conductive paper, or aluminum, zinc, copper-aluminum, copper-stainless steel, chromium- Bimetals such as copper, chrome-copper-aluminum, chrome-lead-iron,
Examples of the conductive support include a base made of a metal plate such as trimetal such as chrome-copper-stainless and the like, and at least one surface of which is hydrophilized. The thickness of these is 0.07 to 2.
0 mm, and more preferably 0.1 to 0.5 mm. Among these substrates, aluminum plates are preferably used. The aluminum plate may contain aluminum as a main component and a slight amount of a different element, and conventionally known and officially used materials can be appropriately used.

From the viewpoint of photoconductive layer film forming property, electrophotographic property, printing durability, etc., at least the surface on which the photoconductive layer is provided has a center line average roughness (Ra) of 0.3 to 0.8 μm. Preferably, it has a rough surface shape of 0.45 to 0.65 μm. Further, it is desirable to have a rough surface shape in which the pit spacing of the rough surface is 30 to 100 μm and the bearing length (Rtp) defined by ISO 4287/1 is 70 to 85% from the viewpoint of elution property.

In order to form these desired surface shapes on the surface of the support on which the photoconductive layer is provided, graining or anodic oxidation may be performed by a known method. Prior to the graining treatment, if desired, a degreasing treatment with a surfactant or an aqueous alkaline solution is carried out. The graining treatment method includes a mechanical surface roughening method, an electrochemical surface roughening method, and a chemical surface selective dissolution method. As the mechanical surface roughening method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method and a buff polishing method can be used. The electrochemical surface roughening method includes a method of performing alternating current or direct current in a hydrochloric acid or nitric acid electrolytic solution. Further, as disclosed in Japanese Patent Laid-Open No. 54-63902, a method of combining the two can be used. The substrate thus roughened is subjected to alkali etching treatment and neutralization treatment as needed before use.

The substrate that has been subjected to the above treatment is anodized to form an oxide film on its surface. As the electrolyte used for the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid or the like, or a mixed acid thereof or the like is used, and the concentration thereof is appropriately determined depending on the kind of the electrolyte. The anodizing condition cannot be unconditionally specified because it varies greatly depending on the electrolyte used, but the amount of anodized film is preferably 0.10 to 10 g / m ² , more preferably 1.0 to 6.0 g / m ^2. Is preferred.

A desired electrophotographic photoconductive layer is provided on the conductive support thus obtained to obtain an electrophotographic lithographic printing plate precursor. The photoconductive layer of the electrophotographic lithographic printing plate precursor according to the invention contains at least a photoconductive compound, and known photoconductive compounds exemplified below can be used. a) triazole derivatives described in U.S. Pat. No. 3,121,197; b) oxadiazole derivatives described in U.S. Pat. No. 3,189,447; c) imidazole derivatives described in Japanese Patent Publication No. 37-16096. d) US Pat. Nos. 3,542,544 and 3,615,402.
No. 3820989, Japanese Patent Publication No. 45-555
No. 51-10983, JP-A-51-93224.
No. 55-108667, No. 55-156953.
And polyarylalkane derivatives described in JP-A-56-36656, e) U.S. Pat. Nos. 3,180,729 and 4,278,746, JP-A-55-88064, and JP-A-55-8806.
5, No. 49-105537, No. 55-51086.
No. 56-80051, No. 56-88141, No. 57-45545 and the like, and pyrazoline derivatives and pyrazolone derivatives, f) U.S. Pat. No. 3,615,404, Japanese Patent Publication No. 46-
3712, 47-28336, JP-A-54-83
No. 435, No. 54-110836, No. 54-1199.
25, etc., phenylenediamine derivatives, g) U.S. Pat. Nos. 3,567,450 and 3,180,703.
No.3, No. 340597, No. 3658520, No. 42
No. 32103, No. 41755961, No. 4012376
Description, West German Patent (DAS) 1110518, JP-B-49-35702, JP-A-39-27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437 and the like. Arylamine derivatives, h) amino-substituted chalcone derivatives described in US Pat. No. 3,526,501, i) N, N-bicarbazyl derivatives described in US Pat. No. 3,542,546, j) described in US Pat. No. 3,257,203, etc. K) styrylanthracene derivative described in JP-A-56-46234, l) fluorenone derivative described in JP-A-54-110837, m) U.S. Pat. No. 3,717,462 54-
59143 (corresponding to US Pat. No. 4,150,987), 55-52063, 55-52064,
55-46760, 55-85495, 57.
-11350, 57-104144, 57-1
Hydrazone derivatives described in US Pat. No. 4,847,493, n) US Pat.
No. 4265990, No. 4273846, No. 42
Benzidine derivatives described in JP-A-99897 and JP-A-4306008, o) JP-A-58-190953 and 59-95540.
No. 59-97148, 59-195658,
Stilbene derivatives described in JP-B No. 62-36674, p) Polyvinylcarbazole and derivatives thereof described in JP-B-34-10966, and q) Polyvinyl compounds described in JP-B-43-18674 and 43-19192. Vinyl polymers such as bilene, polyvinyl anthracene, poly-2-vinyl-4- (4'-dimethylaminophenyl) -5-phenyloxazole and poly-3-vinyl-N-ethylcarbazole, r) JP-B-43-19193 Polymers such as polyacenaphthylene, polyindene, and acenaphthylene / styrene copolymers described in JP-B No. 56-13940, and the like.
Condensation resins such as formaldehyde resin and ethylcarbazole / formaldehyde resin, t) JP-A-56-90883 and 56-161550.
And various triphenylmethane polymers described in Japanese Patent Publication No. 397086, U.S. Pat. No. 4,666,802.
No. 4, Japanese Patent Publication No. 49-4338, No. 49-17535,
JP-A-64-2061, JP-A-64-4389, JP-A-1-144057, JP-A 1-153757, and JP-A 1-2.
No. 17362, No. 1-2221459, No. 1-2529
No. 67, No. 1-285952, No. 1-312551.
No. 2-8256, No. 2-16570, etc., and metal-free or metal phthalocyanines and naphthalocyanines, and derivatives thereof.

The photoconductive compound used in the electrophotographic lithographic printing plate precursor according to the present invention is not limited to the compounds listed in a) to u), and it is possible to use known photoconductive compounds and, if desired, two or more kinds. Can be used as a mixture, but a metal-free or metal-phthalocyanine pigment having photoconductivity is advantageously used in the photoconductive layer of the electrophotographic lithographic printing plate precursor used in the invention.

As the metal phthalocyanine, the central metal of the phthalocyanine ring is lysium, beryllium, sodium, magnesium, aluminum, potassium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, ruthenium,
Rhodium, palladium, silver, cadmium, indium,
Tin, antimony, barium, hafnium, osmium,
Platinum, mercury, lead, and the like, and complex salts in which oxygen or halogen is axially coordinated to these metals are known, and metal-free phthalocyanines are those in which those metals are replaced by hydrogen. Further, for the purpose of improving electrophotographic properties and dispersibility, hydrogen of the benzene ring in the phthalocyanine molecule is halogen, cyano group, nitro group, carboxyl group, sulfonic acid group, alkoxy group, alkylylamino group, alkylamide group, substituted or Derivatives substituted with an unsubstituted aliphatic or aromatic group are also known. Furthermore, the existence of various different crystal forms is known by measuring the X-ray crystal diffraction of these phthalocyanines.

The photoconductive layer in the electrophotographic lithographic printing plate precursor used in the present invention includes, among them, α type, β type, γ
-Type, π-type, τ-type, χ-type, and ε-type metal-free phthalocyanines, α-type, β-type, γ-type, ε-type, and η-type copper phthalocyanines, α-type, β-type and other titanyl phthalocyanines, And a metal phthalocyanine such as halogenoaluminum phthalocyanine are preferable, and a χ-type metal-free phthalocyanine having excellent photosensitivity even in a long wavelength region corresponding to a light source such as a He-Ne laser and a semiconductor laser, and titanyl phthalocyanine are more preferable. Is.

A binder resin is used in combination with the photoconductive layer of the electrophotographic lithographic printing plate precursor used in the present invention to improve the film-forming property and the adhesion to the support. When used as a printing plate, it is necessary to finally remove the photoconductive layer other than the image area. This step depends on the relative relationship between the solubility of the photoconductive layer in the eluate and the resist property of the toner in the eluate. Although it cannot be unconditionally expressed because it is determined, the binder resin is preferably a polymer compound that is soluble or dispersible in the eluate described below.
Further, all the reagents that can be used for the charge holding layer can be used as the binder resin for the photoconductive layer. Even when the charge retention layer and the photoconductive layer are composed of the same type of reagent, the molecular weight, the acid value, etc. may be appropriately changed and used.

The mixing ratio of the photoconductive compound and the binder resin in the photoconductive layer of the electrophotographic lithographic printing original plate used in the present invention is such that various properties such as desired electrophotographic properties and plate-making properties are satisfied. Although it may be determined, the sensitivity is generally low when the content of the photoconductive compound is small, so that it is 5 parts by weight or more, and more preferably 15 parts by weight with respect to 100 parts by weight of the binder resin.
It is preferable to mix and use more than one part by weight. However, the use of 40 parts by weight or more is usually not desirable because the liquid properties such as dispersibility, coating liquid stability and coating property and further improvement of electrophotographic properties cannot be expected. If the thickness of the photoconductive layer is thin, the electric charge necessary for toner development cannot be charged and induces fog due to leakage. Conversely, if it is thick, it not only accelerates the deterioration of the eluent but also induces side etching during elution. Since good image reproducibility cannot be obtained,
m is more preferably 0.50 to 10 μm, further preferably 1.5 to 6.0 μm.

The electrophotographic lithographic printing plate precursor according to the present invention is
It is obtained by coating a photoconductive layer on a conductive support according to a conventional method. In producing the photoconductive layer, a method of containing the components constituting the photoconductive layer in the same layer, or a method of separately containing two or more layers, for example, the lower layer (support side) is easy to dissolve, A method in which a strongly adhesive binder resin is placed and a resin having good chargeability and ink acceptability is placed on the upper layer, or the content of the photoconductive compound is increased, etc., and the layers are separated and used. Are known and can be produced by any method. The coating liquid is prepared by dissolving and dispersing each component constituting the photoconductive layer in a suitable solvent, and when the photoconductive compound uses a component insoluble in the solvent such as phthalocyanine, a ball mill, a dyno mill, an atom. An average particle size of 0.4 μm or less, more preferably 0.2 μm or less is used by dispersing with a disperser such as a lighter or a paint shaker.
Further, in the photoconductive layer, in addition to the photoconductive compound and the binder resin as necessary, a plasticizer, a surfactant, and other components are added in order to improve film properties such as flexibility of the photoconductive layer and coating surface condition. Additives can be added. The additives used in the photoconductive layer can be added during or after the dispersion of the photoconductive compound.

Spin coating of the coating liquid thus prepared,
An electrophotographic lithographic printing plate precursor can be obtained by coating and drying on a conductive support by a known method such as blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, spray coating, and extrusion coating. As the solvent for the coating liquid, various solvents described above as the solvent for the charge retention layer can be used. Further, the concentration (or viscosity) of the coating liquid and the mixing ratio of the solvent are appropriately selected depending on the coating method and the drying device. In the drying of the photoconductive layer-forming coating liquid, the electrophotographic characteristics may be deteriorated particularly due to the drying conditions (temperature and air volume) in the initial drying zone, and therefore it is preferable to set mild drying conditions.

The electrophotographic lithographic printing plate precursor according to the present invention is
A toner image can be formed by a known operation. That is, charging is performed substantially uniformly in a dark place, an electrostatic latent image is formed by imagewise exposure, and then toner development is performed.
Examples of the exposure method include reflection image exposure using a xenon lamp, tungsten lamp, fluorescent lamp, or the like as a light source, contact exposure through a transparent positive film, and scanning exposure using laser light, a light emitting diode, or the like. The light source in the scanning exposure is He-Ne laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, GaAs /
Laser light sources such as semiconductor lasers such as GaAlAs and InGaAsP can be used, or scanning exposure using light emitting diodes and liquid crystal shutters (including line printer type light sources using light emitting diode arrays, liquid crystal shutter arrays, etc.) Is also good.

Next, the electrostatic latent image is developed with toner. As a developing method, any of a dry developing method (cascade developing, magnetic brush developing, powder cloud developing) and liquid developing can be used. In particular, the liquid developing method can form a fine toner image and is suitable for producing a printing plate with good reproducibility. As a developing method, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are possible, but in the present invention, toner is applied to the image exposure portion by reversal development. Develop. The formed toner image can be fixed by a known fixing method such as heat fixing, pressure fixing, solvent fixing and the like. Using the toner image thus formed as a resist, the non-image area photoconductive layer is removed with an eluent to prepare a printing plate.

The toner used for the development of the electrophotographic lithographic printing original plate needs to be composed of at least a resin component having resist properties with respect to the following eluents. Examples of the resin component include acrylic resins made of esters such as methacrylic acid and methacrylic acid, vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, vinylidene chloride resins, vinyl chloride resins, polyvinyl butyral, etc. Vinyl acetal resins, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, etc., polyethylene, polypropylene and its chlorides, polyester resins such as polyethylene terephthalate, polyamide resins such as polycapramide, phenol resins, xylene resins, alkyd resins, Examples thereof include vinyl-modified alkyd resin and other waxes. Further, the toner may contain a dye or a charge control agent as long as it does not adversely affect development or fixing.

In the electrophotographic lithographic printing plate precursor on which the toner development has been completed, at least the non-image area photoconductive layer is eluted and removed by the alkaline elution solution in the elution section. The eluent used for elution of the electrophotographic lithographic printing plate precursor according to the present invention is preferably an aqueous solution containing an alkaline agent and having a buffering capacity near the liquid pH after the preparation of the eluate. The alkali agent to be contained is an inorganic material such as a silicate represented by the general formula SiO ₂ / M ₂ O (M represents an alkali metal atom), an alkali metal hydroxide, an alkali metal such as phosphoric acid or carbonic acid, and an ammonium salt. Alkaline agents, ethanolamines, ethylenediamine, propanediamines, triethylenetetramine,
Organic alkaline agents such as morpholine, and mixtures thereof can be used, but in particular, the above silicates are advantageously used because they exhibit appropriate alkaline strength and strong buffering capacity at high pH.

The above-mentioned eluent is further disclosed in JP-A-55-251.
Ionic compounds described in JP-A-00-00, JP-A-56-142
Water-soluble amphoteric polyelectrolyte described in Japanese Patent No.
A chelating agent described in JP-A 8-190952, JP-A-1-
Liquid viscosity modifiers described in JP-A-177541, JP-A-63-
If desired, known components such as antiseptics and bactericides described in JP-A-226657, various surfactants, and natural and synthetic water-soluble polymers can be contained. The solvent used for the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but soft water is more preferable, and ion-exchanged water is advantageously used. Further, in the solution containing the eluent composition excluding the alkaline agent, in order to more stably mix and disperse the above components, an organic solvent is added and contained together with the eluent active ingredient in a range in which substantially no elution occurs. May be.

In the above silicate-based eluate, it is desirable to add an appropriate amount of alkali metal hydroxide to adjust the pH to a desired range. The final molar ratio of the total amount of alkali metal oxides (M ₂ O) to silicic acid (SiO ₂ ) in the eluate is Si.
The range of O ₂ / M ₂ O = 1 to 2.6 is preferable, and further 1.3 to 2.
2 is preferred. In addition, the concentration of the alkaline agent in the eluate is one of the main factors that determine the elution rate, and its concentration ranges from 1 to
The range of 10% by weight, more preferably 2 to 8% by weight,
It is more preferably 3 to 5% by weight. The pH of the eluate is
12.0 to 13.5, and more preferably 12.3 to 13.0.

If the elution time, that is, the time from the contact of the eluate with the photoconductive layer to the removal thereof, is short, poor elution and scumming during printing are caused, and if it is long, the fine line and the image are removed. Cause a fall. However, for the charge retention layer, even if the contact time with the eluate is slightly longer, both have practically no adverse effects, so the contact time is set to be equal to the elution time or more preferably longer. .. In addition,
It is not a good idea to mechanically remove the solubilized photoconductive layer in the elution part as described in JP-A-60824, but it is preferable to remove the elution type charge retention layer in the elution part. Therefore, it is desirable to provide an eluate supply means for exclusive use of the elution type charge retention layer and a scraping means for removing the elution type charge retention layer at least in the elution part.

The printing plate from which at least the non-image area photoconductive layer is eluted and removed is then rinsed to remove the solubilized photoconductive layer component remaining on the plate by rinsing the plate surface. The rinse liquid used for the rinse is adjusted so that the eluent soluble resin used in the electrophotographic lithographic printing plate precursor according to the present invention does not reaggregate. That is, unless the initial pH of the rinse liquid promotes the insolubilization of the resin to a minimum, the resin flowing in together with the eluate is kept in the solubilized state, so that the trouble due to the reinsolubilization of the resin can be prevented. However, on the contrary, if the pH of the rinse liquid is high, not only the elution effect is exhibited and the side etching is deteriorated, but also a slight amount of the rinse liquid flows into the protective gum liquid for the plate surface protective treatment which is usually performed thereafter. The pH of the rinse liquid inevitably rises at an early stage and the plate surface protection effect is also attenuated.

The printing plate whose plate surface has been rinsed by the rinsing treatment is subjected to a protective gum treatment for the purpose of improving scratch resistance of the plate surface and desensitizing the non-image area. The protective gum solution that can be used in the present invention, other than hydrophilic polymer compounds such as gum arabic, organic and inorganic acids, acidic buffers, lipophilic substances,
Alternatively, known agents can be used for all these reagents including a surfactant and the like.

[0054]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 A JIS 1050 aluminum sheet (thickness: 0.3 mm) was grained with a rotating nylon brush using a pumice-water suspension as an abrasive. After washing with water, dip it in a 10% sodium hydroxide solution at 60 ° C to dissolve aluminum in an amount of 6g /
Etching was performed so as to be m ² . After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute for neutralization, and then thoroughly washed with water. Then 3
Electrolysis surface roughening was performed in a 35% aqueous solution of hydrochloric acid at 35 A / dm ² for 50 seconds, and the surface was washed by immersing it in a 20% sulfuric acid aqueous solution at 50 ° C. and then washed with water. Further, anodizing treatment was performed in a 20% aqueous solution of sulfuric acid to form an aluminum oxide film on the surface, which was washed with water and dried to obtain a support. The surface roughness (Ra) of the surface-treated surface at this time was 0.57 μm.

On the surface-treated surface of this support, the coating liquid for forming a photoconductive layer (Photoconductive layer No. 1) shown in Table 1 dispersed for 1 hour with Dynomill was applied with an extrusion coater to give a solid content of 4. After coating so as to be 4 g / m ² , it was dried at 90 ° C. for 30 seconds.

[0057]

[Table 1] Coating liquid formulation for photoconductive layer formation (photoconductive layer N
O.1)

A slip sheet in which low-density polyethylene was laminated to a thickness of about 10 μm on one surface having a basis weight of 46 g / m ² and the obtained electrophotographic lithographic printing plate precursor were sandwiched so that the polyethylene surface was in contact with the photoconductive layer surface, and guillotine was used. 275 x 475 with cutter
Cut into mm and apply the coating liquid for forming the charge retention layer (retention layer NO.1) shown in Table 2 on the end face of the long side (475 mm side) with a sponge so that the solid content is about 3 g / m ² . Then, it was dried at room temperature.

[0059]

[Table 2] Formulation of coating liquid for forming charge retention layer (retention layer N
O.1)

FIG. 1 shows the basic structure of the corona charging section of the plate-making processing apparatus used in this embodiment. The electrophotographic lithographic printing original plate 1 having the charge holding layer 4 provided on the end face 5 on the printing original plate side is conveyed onto the surface plate 10 by a printing original plate conveying means (not shown),
The positioning pin 15 and a pin pressing means (not shown) are placed at a fixed position on the surface plate 10 and fixed on the surface plate 10 by a printing original plate suction fixing means (not shown). The corotron charger 8 is arranged on the surface plate 10, and the driving force is transmitted to the shaft 12 arranged under the surface plate 10 by the surface plate operating means (not shown).
The printing original plate 1 is placed on a surface plate 10 and is charged while moving under a charger 8.

Contact part 17 with the back surface of printing original plate 1 of platen 10
Width (width in the direction perpendicular to the platen moving direction) is 267 mm
And, the lower part of the end face 5 on the printing original plate side at both ends has a depth of 5 mm.
The side groove 18 is cut so that the printing master plate side end surface 5 is always arranged on the side groove 18 by the positioning pin 15 so that the printing master plate side end surface 5 does not contact the surface plate 10 main body.
The surface plate 10 is made of cast iron, and the positioning pin 15 is made of Teflon.

The printing original plate (original plate No. 1) which was left at room temperature after being shielded from light and heated at 50 ° C. for 2 hours was charged by the corona charging means so that the surface potential of the photoconductive layer became about + 280V. After that, scanning image exposure was performed using a semiconductor laser (780 nm), and immediately positive charge toner (Mitsubishi Paper Mills Co., Ltd.)
Inversion development (bias voltage: +120 V) was performed by using LOM-ED III) manufactured by Mfg. Co., Ltd., dried with cold air to remove the toner dispersion medium, and then heat-fixed to form a toner image on the photoconductive layer. When the end surface of the printing original plate side was observed after the toner development, almost no toner adhesion was observed on the charge retention layer.

The printing plate thus developed with the toner was used as an eluent having the composition shown in Table 3 below (eluent NO. 1).
After immersing in water for 7 seconds, it was thoroughly washed with a sponge including the side end faces and then gummed. The charge retention layer on the end surface of the printing original plate was removed at the latest during washing with water, and at least no toner remained on the side end surface.

[0064]

[Table 3] Eluent formulation (Eluent NO.1)

When the obtained printing plate was printed on an A3 size paper by an offset printing machine (Ryobi 3200 MCD), the printing plate non-image area and the printing plate side end surface were of course stained. A good printed matter was obtained without any defects.

Comparative Example 1 The printing original plate (original plate No. 2) provided with no charge retention layer coated in Example 1 was prepared under the same processing conditions as in Example 1. As a result, at least the toner on the side end surface was not removed even after the elution treatment. When printing was carried out under the same conditions as in Example 1 using this printing plate, the print plate obtained showed good printability without stains in the part corresponding to the non-image part of the printing plate. Stain-like stains were generated in the portion corresponding to the end face, which was not suitable for practical use.

Comparative Example 2 Plate-making processing apparatus used in Example 1 Surface plate 10 of corona charging section
A printing plate precursor similar to that of Example 1 was used, except that a smooth cast iron material having a thickness of 5 mm was arranged in the groove 18 to form a platen having a width substantially wider than that of the printing plate precursor 1. Toner development processing was performed. As a result, a considerable amount of toner adhered to the end surface of the printing original plate on which toner development has been completed, and the toner on the side end surface was hardly removed even after the elution treatment. When printing was carried out in the same manner as in Example 1 using this printing plate,
The portion of the obtained printed matter corresponding to the non-image area of the printing plate showed good printability without stains, but streaky stains were generated in the portion corresponding to the end face of the printing plate, and practical use It was not suitable for.

Example 2 Comparative Example 2 is completely different from Comparative Example 2 except that a vinyl chloride resin material (insulating member NO. 1) having the same shape is arranged instead of the cast iron material arranged in the side groove 18 of the surface plate 10 in Comparative Example 1. A printing plate was produced by the same operation. No toner was attached to the end surface of the printing plate after the plate making process, and when this printing plate was printed,
A good printed matter was obtained in which no stain was found at the portion corresponding to the printing plate non-image portion as well as the portion corresponding to the end face on the printing plate side.

Similarly, the Teflon material (insulating member NO. 2), epoxy resin material (insulating member NO. 3) and silicone rubber material (insulating member NO. 4) and acrylic resin material (insulating material NO.
A printing plate was prepared in the same manner as in Comparative Example 2 except that 5) was arranged. In all cases, no toner was attached to the end surface of the printing plate side after the completion of the plate-making process, and the same results as in Example 1 were obtained in the printing performed using these printing plates. ..

Example 3 In place of the charge retaining layer forming coating liquid (retaining layer NO. 1) coated on the end surface of the printing original plate in Example 1, the charge retaining layer forming coating liquids (Table 4 to Table 7) ( The holding layers No. 2 to 5) were coated with a sponge so that the coating amount of solid content was about 2 g / m ^2, and then dried at room temperature.

[0071]

[Table 4] Formulation of coating liquid for forming charge retention layer (retention layer NO.
2)

[0072]

[Table 5] Formulation of coating liquid for forming charge retention layer (retention layer N
O.3)

[0073]

[Table 6] Formulation of coating liquid for forming charge retention layer (retention layer N
O.4)

[0074]

[Table 7] Formulation of coating liquid for forming charge retention layer (retention layer N
O.5)

The printing original plate (original plate Nos. 3 to 6) which was left at room temperature after being shielded from light and heated at 50 ° C. was subjected to corona charging, scanning image exposure, and toner development treatment under the same conditions as in Example 1. Then, the toner image was formed on the printing original plate. When the end faces of the respective printing original plates were observed after the toner development, almost no toner adhesion was observed on the charge retaining layers of all the original printing plates. Next, these stamp original plates are shown in Table 8 below.
After dipping for 7 seconds in the eluate having the composition as shown in (Eluate NO.2), it was thoroughly washed with a sponge including the side end faces and then gummed. As a result, all the charge retention layers on the end faces of the printing original plate were removed at the latest during washing with water, and at least no toner remained on the side end faces.

[0076]

[Table 8] Eluent formulation (Eluent NO.2)

The obtained four types of printing plates were printed under the same conditions as in Example 1. As for any of the printing plates, not only the printing plate non-image portion but also the printing plate side end face was printed. A good print without any stains was obtained.

Example 4 The undercoat layer-forming coating liquid (undercoating No. 1) shown in Table 9 was applied to the end surface of the unprocessed printing original plate after cutting the guillotine cutter prepared in Example 1 using a sponge as a solid content. The amount is about 2g / m ²
After coating, the coating solution for the charge retentive layer used in Example 1 (retaining layer NO.1) was applied with a sponge to give a solid content of about 2 g / m ² . After being coated so as to become, the coating was dried at room temperature.

[0079]

[Table 9] Coating liquid formulation for forming the undercoat layer (undercoat NO.
1)

The obtained printing original plate (original plate No. 7) was shielded from light and heated at 50 ° C. for 2 hours, and then allowed to stand at room temperature. Corona charging, scanning image exposure under the same conditions as in Example 1 in the dark. Then, toner development processing was performed to form a toner image on the printing original plate. When the end faces of the respective printing original plates were observed after the toner development, almost no toner adhesion was observed on the charge retaining layers of all the original printing plates. This printing original plate was immersed in the eluate (eluate NO.2) for 7 seconds, washed thoroughly with a sponge including the side end faces, and then gummed. Subsequently, this printing plate was printed under the same conditions as in Example 1, and as in Example 1, there was no stain at all in the parts corresponding to the printing plate non-image areas as well as the parts corresponding to the printing plate side end faces. A printed matter was obtained.

Example 5 Undercoat layer forming coating solution used in Example 4 (undercoat NO. 1)
And the charge retaining layer forming coating liquid (retaining layer NO.1),
The coating liquid for forming the undercoat layer (undercoating NO. 2) shown in Table 10 and the coating liquid for forming the charge retention layer described in Example 3 were formed on the end surface of the unprocessed side of the printing original plate after cutting the guillotine cutter prepared in Example 1. (Retaining layer No. 3) was applied and laminated with a sponge so that the solid content applied amount was about 2 g / m ² .

[0082]

[Table 10] Formulation of coating liquid for forming the undercoat layer (undercoat NO.
2)

The obtained printing original plate (original plate No. 7) was shielded from light and heated at 50 ° C. for 2 hours and then allowed to stand at room temperature, and in the dark, a platen using the insulating member NO. Then, under the same conditions as in Example 2, corona charging, scanning image exposure, and toner development processing were performed to form a toner image on the printing original plate. When the end faces of the respective printing original plates were observed after the toner development, no toner adhesion was observed on the printing original plate charge retention layer. The obtained toner-developed printing plate was dipped in the eluate (eluate NO. 2) for 7 seconds, washed thoroughly with a sponge including the side end faces, and then gummed. Subsequently, this printing plate was printed under the same conditions as in Example 1, and as in Example 1, there was no stain at all in the parts corresponding to the printing plate non-image areas as well as the parts corresponding to the printing plate side end faces. A printed matter was obtained.

Example 6 The coating liquid for forming the photoconductive layer used in Example 1 (photoconductive layer NO.
In place of 1), the coating liquid for forming a photoconductive layer (photoconductive layer NO.2) shown in Table 11 is applied, and the coating liquid for forming a charge retention layer (holding layer NO.6) shown in Table 12 is further applied to the side end faces. ) Was coated, and an electrophotographic lithographic printing original plate was prepared by the same procedure as in Example 1 including the method for preparing each coating solution.

[0085]

[Table 11]

[0086]

[Table 12] Formulation of coating liquid for forming charge retention layer (retention layer N
O.6)

The obtained printing original plate (original plate No. 8) was shielded from light and heated at 50 ° C. for 2 hours and then left at room temperature, and the surface potential of the photoconductive layer on the platen used in Example 1 was adjusted. About +40
After charging to 0 V, the negative image is exposed with tungsten light, and then reverse development (bias voltage: +100 V) is immediately performed using positively charged toner (Fuji Photo Film Co., Ltd. ELP-TX1), and cold air is applied. After drying to remove the toner dispersion medium, heat fixing was performed to form a toner image on the photoconductive layer. When the end surface of the printing original plate side after the toner development was observed, toner adhesion was not seen so much on the charge retentive layer.

The printing original plate on which the toner has been developed obtained above was used as an eluent having the composition shown in Table 13 below (eluent NO.
After dipping in 3) to dissolve and remove the non-image area and the charge retentive layer, it was thoroughly washed with sponge including the side end faces and then gummed. The charge retention layer on the end surface of the printing original plate was removed at the latest during washing with water, and at least no toner remained on the side end surface.

[0089]

[Table 13] Eluent formulation (Eluent NO.3)

When the obtained printing plate was printed on an A3 size paper by an offset printing machine (Ryobi 3200 MCD), not only the non-image part of the printing plate but also the part corresponding to the end face of the printing plate was stained. A good printed matter was obtained without any defects.

Example 7 The electrophotographic lithographic printing original plate prepared in Example 6 (original plate NO.
8) is used instead of the surface plate used in Example 6 in Example 2
A printing plate was prepared in the same manner as in Example 6 except that the surface plate used in combination with the silicone rubber material (insulating member No. 4) was used. As a result, no toner adhered to the end surface of the printing plate after the plate-making process, and in the printing performed using this printing plate, as in Example 1, the printing plate non-image portion Needless to say, a good printed matter was obtained without any stains on the portion corresponding to the end face of the printing plate.

Example 8 A coating liquid for forming an undercoat layer shown in Table 14 (undercoating NO.) Was formed on the end surface of the unprocessed side of the printing original plate after coating the photoconductive layer used in Example 6.
3) and the charge retaining layer forming coating liquid described in Example 3 (retaining layer).
NO.4) with a sponge, the solid coating amount is about 2 g / m ²
It was coated and laminated so that

[0093]

[Table 14] Coating liquid formulation for forming the undercoat layer (undercoat NO.
3)

The obtained printing original plate (original plate No. 9) was shielded from light and heated at 50 ° C. for 2 hours, and then left at room temperature. Corona charging, scanning image exposure under the same conditions as in Example 1 in the dark. Then, toner development processing was performed to form a toner image on the printing original plate. When the end surface of the printing original plate side after the toner development was observed, no toner adhesion was observed on the printing original plate charge retention layer. The obtained toner-developed printing plate was immersed in an eluate (eluate NO.3) to dissolve and remove the non-image area, the charge retention layer, and the undercoat layer, and then washed thoroughly with a sponge including the side edges. Then I chewed gum. Subsequently, this printing plate was printed under the same conditions as in Example 1, and as in Example 1, there was no stain at all in the parts corresponding to the printing plate non-image areas as well as the parts corresponding to the printing plate side end faces. A printed matter was obtained.

Comparative Example 3 Hydrophilic undercoat layer coated in Example 8 (undercoat NO.
3) was provided, and the printing original plate (original plate NO. 10) without the charge holding layer (holding layer NO. 4) was used, and toner development was performed under the same conditions as in Example 8. As a result, a considerable amount of toner adhered to the undercoat layer on the end surface of the printing original plate on which the toner development has been completed, and the toner on the side end surface was not completely removed even after the elution treatment. Example 1 using this printing plate
When printing was performed in the same manner as described above, the portion of the obtained printed matter corresponding to the non-image area of the printing plate showed good printability without stain, but at least the toner was found in the portion corresponding to the end surface of the printing plate. Stripe-like printing stains were generated in the area where the marks adhered, which was not suitable for practical use.

Example 9 A coating liquid for forming an undercoat layer shown in Table 15 (Undercoating NO.) Was formed on the end surface of the unprocessed side of the printing original plate after coating the photoconductive layer used in Example 6.
After applying 4) so that the solid content coating amount becomes about 2 g / m ² ,
It was thoroughly dried at 50 ° C. A coating liquid for forming a charge retentive layer (retaining layer No. 7) shown in Table 16 was coated and laminated on the surface of the undercoat layer so that the solid coating amount was about 3 g / m ^2, and air-dried at room temperature to remove the solvent. After the removal, the printing original plate (original plate No. 11) was obtained by drying at 100 ° C. for 2 minutes.

[0097]

[Table 15] Formulation of coating liquid for forming the undercoat layer (undercoating NO.
4)

[0098]

[Table 16] Formulation of coating liquid for forming charge retention layer (retention layer
NO.7)

The obtained printing original plate was subjected to corona charging, scanning image exposure, and toner development treatment in the dark under the same conditions as in Example 8 to form a toner image on the printing original plate. When the end surface of the printing original plate side after the toner development was observed, no toner adhered to the charge holding layer of the printing original plate. The obtained printing plate on which the toner has been developed is used as an eluent (eluent NO.
After dipping in 3) to dissolve and remove at least the non-image area,
After thoroughly washing with a sponge including the side end faces, gum was applied. Subsequently, this printing plate was printed under the same conditions as in Example 8, and as in Example 8, there was no stain at all in the part corresponding to the printing plate non-image portion and of course to the end surface of the printing plate. A printed matter was obtained.

Comparative Example 4 Toner development was carried out under the same conditions as in Comparative Example 2 except that the printing original plate (original plate No. 11) prepared in Example 9 was used. As a result, the toner adhered on the end surface silicone resin layer on which the toner has been developed, especially on the interface surface between the silicone resin layer and the photoconductive layer, and the toner on the side end surface was almost removed even after the elution treatment. There wasn't. When printing was carried out in the same manner as in Example 1 using this printing plate, the area corresponding to the non-image area of the printing plate of the obtained printed matter showed good printability without stains, but In the corresponding portion, although it gradually thinned and disappeared over time after printing, streaky stains were generated in the portion, which was not suitable for practical use.

As described above, when an electrophotographic lithographic printing plate precursor is prepared by the method for making an electrophotographic lithographic printing plate according to the present invention, toner adhesion on the end surface of the printing plate precursor can be suppressed and the charge retention layer of the charge holding layer can be suppressed. It is possible to prevent an elution residue and prevent the side end surface streaky print stain caused by the elution residue, and to provide an excellent effect that a good printed matter can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a surface plate having a side groove in the vicinity of a side end surface of an electrophotographic lithographic printing plate precursor that is used for carrying out a method for making an electrophotographic lithographic printing plate according to the present invention.

[Explanation of symbols]

 1 Electrophotographic planographic printing original plate 4 Charge retention layer 5 Printing original plate side end surface 8 Corotron charger 10 Surface plate 18 Side groove

Claims (2)

[Claims] 1. A toner image is formed by an electrophotographic method on an electrophotographic lithographic printing plate precursor in which a photoconductive layer is provided on a conductive support and at least a charge holding layer is provided on a side end surface thereof.
Next, in the plate making method of the electrophotographic lithographic printing plate in which at least the non-image area photoconductive layer other than the toner image area is removed to form a printing plate, the side formed by the charge holding layer on the printing original plate side and the back surface of the conductive support From the above, a method for making an electrophotographic lithographic printing plate is characterized by holding at least a space corresponding to the thickness of the printing original plate in an insulating atmosphere to charge the electrophotographic lithographic printing plate. 2. A platen for charging an electrophotographic lithographic printing plate precursor having a photoconductive layer provided on a conductive support and at least a charge holding layer on its side end face while holding it at a fixed position. 2. The electrophotographic photograph according to claim 1, wherein the printing original plate is charged on a surface plate composed of an insulating member at least a width corresponding to a thickness of the printing original plate from a portion where the end face charge holding layer on the original plate side and the surface plate contact each other. How to make a lithographic printing plate.