JPH08146670A - Processing method of electrophotographic planographic printing plate - Google Patents

Abstract

PURPOSE: To provide a processing method of an electrophotographic planographic printing plate by which not only the whole surface of the plate is uniformly processed without defects in the plate but stable processing is obtd. for a long time while fatigue of a rinsing liquid is suppressed to decrease the exchanging times for liquids. CONSTITUTION: In this processing method of an electrophotographic planographic printing plate, an eluting liquid is supplied on the surface of an electrophotographic planographic printing plate where a toner image is formed on a photoconductive layer so that the nonimage part of the photoconductive layer is swollen and rendered to be soluble. After the photoconductive layer rendered into soluble is removed by a removing means. Then the plate surface is rinsed with a rinsing liquid. In this processing method, before the photoconductive layer rendered into soluble is removed by the removing means, a processing liquid is supplied to the plate surface by 20-300ml/m<2> amt. for a unit printing plate area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process of an electrophotographic lithographic printing plate for producing a printing plate by removing the non-image area photoconductive layer of an electrophotographic lithographic printing plate having a toner image formed on the photoconductive layer. The present invention relates to a method for processing an electrophotographic lithographic printing plate that can perform stable quality processing over a long period of time without causing plate-making defects, and further reduce the frequency of liquid exchange and waste liquid.

[0002]

2. Description of the Related Art A non-image area alkali-eluting electrophotographic lithographic printing plate generally comprises a photoconductive layer comprising a photoconductive substance and an alkali-soluble binder resin provided on a conductive support.
A toner image is formed on the photoconductive layer by an electrophotographic method, and in the elution step, the non-image area photoconductive layer other than the toner image area is solubilized and eluted by an eluent containing an alkaline agent and the like, followed by a rinse. In the processing step, a rinsing liquid is supplied to wash and remove the solubilized photoconductive layer components remaining on the plate surface, and then, a protective gum treatment is usually carried out for printing.

The elution step utilizes the difference between the alkali solubility of the toner and that of the photoconductive layer, and the photoconductive layer itself on which the toner image is formed is not essentially alkali-insoluble. Therefore, if the elution is promoted, the elution liquid called side etching from the side surface of the photoconductive layer also erodes the photoconductive layer in the image area, so that the image line is thin and good image reproducibility cannot be obtained. In addition, if the solubilized photoconductive layer component flows into the eluate, the elution ability may be lowered due to the recycling and reuse, which may lead to elution failure.

Therefore, in the elution step, the components of the photoconductive layer are not dissolved and only a small amount of the eluent is used to swell and solubilize, and the photoconductive layer solubilized in the next step is removed to prevent the photoconductive layer from being mixed into the eluate. The method of doing is adopted. However, even if the inclusion of the solubilized product in the corner eluate is suppressed, the removal efficiency of the solubilized photoconductive layer component has a great influence on the rinse process in the next step, and the plate making and the printing quality are deteriorated. You might even invite me.

That is, if the content of the removed substance in the processing liquid after the next step increases, the side etch is aggravated by the increase of the liquid pH, and if the removed component becomes insoluble in the processing liquid, it is transferred to the plate. It causes printing stains and deterioration of the function of the processing liquid circulation system due to redeposition. Further, even if the above defects do not appear, the photoconductive substance contained in the photoconductive layer is generally a highly concealing colored substance, and the treatment liquid supplied to the plate remains after the rinsing treatment to some extent. When a large amount of photoconductive substance is mixed in the treatment liquid used for rinsing, a large amount of photoconductive substance remains on the plate surface, and it is difficult to distinguish at first glance whether it is poor elution or poor rinsing. There is a drawback in that the treatment liquid that is strongly colored flows into the coating process) and the liquid exchange frequency increases even in the treatment liquid of the next process for the same reason.

[0006]

SUMMARY OF THE INVENTION The present invention is an electrophotographic lithographic printing plate for producing a printing plate by removing the non-image area photoconductive layer of an electrophotographic lithographic printing plate having a toner image formed on the photoconductive layer. In the processing method of (1), it is possible to prevent elution defects such as a residual film while suppressing side etching, and to elute the entire surface of the plate uniformly. It is an object of the present invention to provide a treatment method that suppresses the deterioration of properties and can perform stable treatment over a long period of time, and that the frequency of liquid exchange is greatly reduced, thereby reducing the burden of waste liquid and maintenance management. More specifically, it is an object of the present invention to provide a method for treating an electrophotographic lithographic printing plate which improves substantially and apparently various treatment defects due to fatigue of a rinse liquid which is circulated and reused in the rinse treatment step.

[0007]

As a result of repeated studies to solve the above problems, as a result of supplying an eluent to the image forming surface of an electrophotographic lithographic printing plate having a toner image formed on a photoconductive layer, a non-image is formed. Part of the photoconductive layer is swelled and solubilized, and the photoconductive layer solubilized by the removing means is removed, and then the plate surface is rinsed with a rinse liquid. This was achieved by a method for treating an electrophotographic lithographic printing plate in which a treatment liquid was supplied to the plate surface prior to the removal of the photoconductive layer, and the amount of the treatment liquid supplied per unit printing plate area was 20 to 300 ml / m ² .

In the present invention, when the eluate is supplied to the toner image forming surface of the electrophotographic lithographic printing plate to swell and solubilize the non-image area photoconductive layer, and the solubilized photoconductive layer is removed by the removing means. It has been found that the removal efficiency becomes worse as the removed product becomes more viscous regardless of the removal means. In order to reduce the viscosity of the solubilized photoconductive layer that is the removed substance, it can be dealt with by increasing the swelling degree of the photoconductive layer in the elution step by adjusting the eluent components, but The increase means an increase in the eluate in the discarded material to be discarded, and the photoconductive layer component is more likely to be dissolved and mixed in the eluent to be reused, which accelerates the deterioration of the eluate.

Therefore, the treatment liquid is supplied to the plate surface prior to the removal of the solubilized photoconductive layer by the removing means, whereby the solubilized photoconductive layer component is diffused and dissolved in the supplied treatment liquid to lower the viscosity. As a result, the ability to remove the solubilized photoconductive layer can be improved while suppressing the consumption of the eluate. Furthermore, if the rinse liquid used for cleaning the plate surface in the next step is used as the treatment liquid supplied to the solubilized product, the rinse liquid fatigue can be delayed by supplementing the unused liquid to the rinse step.

The processing method of the present invention will be described in detail below in order according to the plate making process. In the present invention, an eluate is supplied to the image forming surface of an electrophotographic lithographic printing plate having a toner image formed on the photoconductive layer to swell and solubilize the non-image area photoconductive layer (solubilizing step), and a removing means. In the method for treating an electrophotographic lithographic printing plate, which comprises rinsing the plate surface with a rinsing solution (removing step) after removing the photoconductive layer solubilized by This is a processing method in which a processing liquid is supplied to the printing plate prior to removal.

In the solubilization step, an eluate is supplied to the image forming surface of the electrophotographic lithographic printing plate on which a toner image has been formed by the electrophotographic method to swell and solubilize the non-image area photoconductive layer other than the toner image area. . The eluate supply system is a conventionally known mechanism,
For example, a shower, a slide hopper, a curtain coater, and a dip method can be used, but in order to prevent the swelling-solubilized photoconductive layer component from diffusing into the eluate, it is possible to supply softly in any method. desirable. Particularly when a shower is used, it is preferable to use a system in which the liquid discharged from a tube is rectified into an eluate through a rectifying plate, a roll, or the like and uniformly supplied to the image forming surface.

It is important that the minimum supply amount of the eluate is such that the eluate flows down from the edge of the plate during the transportation up to the removal step. As a result, a part of the photoconductive layer in the non-image area is swollen and solubilized, and the excess part flows over the plate and partially flows down from the plate edge part while partially replacing the eluate existing in the part to be eluted. Therefore, liquid replacement frequently occurs at the plate edge, and the eluate flow rate near the interface of the photoconductive layer increases, so that intraplate fluctuation of the elution degree is suppressed. In addition, in order to prevent liquid supply failure and further shorten the elution time, a flow promoting mechanism is provided during the removal process to replace the eluent on the plate, and the eluate can be used multiple times. It is desirable to supply it.

The eluent according to the present invention preferably contains an alkaline agent and has a buffering capacity. Conventionally, as an alkaline agent used in a developing solution for a photosensitive lithographic printing plate (PS plate), a general formula SiO ₂ / M ₂ O (M = Li, Na,
K) inorganic alkali agents such as silicates, alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, alkylcumines, ethanolamines,
Organic alkaline agents such as ethylenediamine, triethylenetetramine, and morpholine, and mixtures thereof. Of these, the above-mentioned silicates in particular exhibit a strong buffering ability and promote the swelling and solubilization of the photoconductive layer, but can suppress the diffusion of the solubilized product into the liquid, so that the eluent according to the present invention is at least It shall contain a silicate.

The eluent is further disclosed in JP-A-55-25100.
Ionic compounds described in JP-A-55-95946
Water-soluble cationic polymers described in JP-A-56-
Water-soluble amphoteric polymer electrolytes described in JP-A-142528, neutral salts described in JP-A-58-75152, and JP-A-58.
-190952, the chelating agent described in JP-A-1-1
Liquid viscosity adjusting agent described in Japanese Patent No. 77541, JP-A-63-2
If necessary, known components such as antiseptics and bactericides described in JP-B 26657, various surfactants, and natural and synthetic water-soluble polymers can be added.

The preferred properties of the silicate used in the eluate are:
_{SiO 2 / M 2 O = 0.5~8.5} ( molar basis) better, more preferably in the range of 1.2 to 4.0. When it is used as an eluent, an appropriate amount of alkali metal hydroxide is further added, and SiO _{2 is} added.
The range of / M ₂ O = 1.2 to 3.6 is preferable. The concentration of the alkaline agent in the eluate is one of the main factors that determine the elution property, but in the present invention, it is 1 to 30% by weight, more preferably 2 to 15% by weight. The pH of the eluate is 11.
5 to 14.0, more preferably 12.0 to 13.5, is preferable.
It is desirable to add a desired replenisher solution in a timely manner to improve the elution activity.

In the solubilizing step, the eluate on the plate is not entirely consumed for solubilizing the photoconductive layer, and in the removing step, all the liquid matter on the plate is removed. During the removal process after the completion of solubilization, a fixed amount of the eluate on the plate may be left to be measured and removed by the liquid measuring means. When measuring liquid, it is important to prevent the solubilized photoconductive layer from mixing into the effluent while removing the effluent that was not involved in the solubilization of the photoconductive layer from the plate as much as possible. is there. The activity of the eluate can be further maintained by removing and discarding the eluate that is exhausted due to the mixing of the components of the photoconductive layer together with the solubilized photoconductive layer.

The electrophotographic lithographic printing plate having the photoconductive layer solubilized is subjected to a removing step to remove the eluent remaining on the plate and the solubilized photoconductive layer by the removing means. In this case, only the solubilized photoconductive layer is solubilized, and the solubilized photoconductive layer is set so that the solubilized photoconductive layer components are not diffused and mixed into the eluate that is circulated and reused in the elution process. When the conductive layer is swollen with the eluate, the corresponding layer of the leopard is tight, and naturally the viscosity of the solubilized photoconductive layer is also extremely high. Adhesion increases, which is not preferable. Therefore, the treatment liquid is supplied to the plate surface prior to the removal of the solubilized photoconductive layer by the removal means, thereby lowering the viscosity of the removal component and improving the removal efficiency.

Therefore, it is essential to rapidly dissolve and / or disperse the photoconductive layer component solubilized in the supplied processing liquid to reduce the viscosity of the removed substance. However, the effect cannot be expected even if the solution supply system similar to the elution treatment is adopted for the solubilized photoconductive layer component that does not even diffuse into the eluate. Therefore, even if the scattering of the treatment liquid and / or the mixed liquid is neglected to some extent, the mechanism must improve the removability as a result. As a method of decreasing the viscosity of the solubilized photoconductive layer component by the supplied processing liquid, the processing liquid is compressed and supplied by high-pressure spray, etc., or the processing liquid is accelerated and supplied, or the processing liquid is supplied. Simultaneously with or immediately after that, the solubilized photoconductive layer is disturbed by a brush or a molton, or in any case, the treatment liquid is forcibly permeated or mixed.

The treatment liquid supplied to the plate surface prior to the removal of the solubilized photoconductive layer by the removing means according to the present invention is preferably a liquid having the effect of rapidly dissolving or dispersing the solubilized photoconductive layer component. However, it does not matter if the composition is such that side etching proceeds by supplying a minimum amount of processing liquid, or conversely, the solubilized portion is re-insolubilized. Therefore, as the treatment liquid according to the present invention, in addition to tap water, an elution-stopping liquid, a rinsing liquid, a washing liquid, and a rinse-stopping liquid used in the conventional plate-making treatment, and a plate making apparatus for electrophotographic lithographic printing plates according to the present invention are used. A cleaning liquid mainly for cleaning can be used.

The treatment liquid according to the present invention is discarded after being removed from the plate together with the solubilized photoconductive layer component in any case, so that it is not necessarily an unused liquid as long as the effect is substantially the same. The used liquid supplied to the plate surface and / or the opposite surface at least once, and / or the cleaning liquid used for cleaning the processing apparatus, or the liquid containing the used liquid may be used. Taking all these things together,
It is preferable to use a rinse liquid that has been recycled and reused as the treatment liquid according to the present invention.

The supply amount of the treatment liquid according to the present invention per unit area of the printing plate is 20 to 300 ml / m ² , and the more preferable supply amount is 50 to 200 ml / m ² . When the supply amount of the treatment liquid is less than 20 ml / m ² , even if all of the treatment liquid is mixed with the rapidly solubilized photoconductive layer component, the removal efficiency is not so improved because the viscosity of the mixture is still high. On the contrary, even if the supply amount of the treatment liquid is more than 300 ml / m ^2, further improvement of the removal efficiency is not seen and the amount of waste liquid increases, which is not preferable. The removability of the solubilized photoconductive layer varies depending on the photoconductive layer components, eluate, and elution conditions such as liquid temperature and liquid supply method. Therefore, it is desirable to set the minimum amount so that the removal efficiency does not deteriorate.

The electrophotographic lithographic printing plate, to which the treatment liquid is supplied to the solubilized photoconductive layer, removes the solubilized photoconductive layer component together with the treatment liquid by the removing means. As the removing means according to the present invention, squeeze rolls, scraping blades, roll-shaped and flat brushes, and contact-type means such as Molton,
Non-contact type means such as compressed air blowing may be mentioned, and among these, squeeze rolls and scraping blades are preferably used.

The squeeze roll can remove the substances removed from the plate surface by passing the printing plate between the pair of rolls and the nip pressure thereof. Further, the scraping blade is arranged such that an elastic material such as metal, plastic, or rubber having a smooth contact surface with the plate is arranged along the conveying path of the printing plate, and the elastic material is bent in the plate surface direction to make the plate surface. It is possible to remove the material removed from the printing plate by sliding it into contact with. When installing the scraping blade, a guide roller that rotates at a peripheral speed equal to or higher than the transfer speed is provided under the blade, or pressure is applied immediately after the plate leading edge passes through the scraping blade to prevent the occurrence of conveyance defects. It is desirable to provide some kind of mechanism.

If the treatment liquid is supplied to the plate surface prior to the removal of the solubilized photoconductive layer by the removing means, the removing efficiency is good and the removed material is less likely to remain in the removing means, but the removal efficiency is maintained. In order to do so, the removing means may be washed within a certain period of time immediately after the printing plate has passed through the removing means. The cleaning of the removing means does not have to be performed during the continuous plate making, and if the next plate-making product is carried into the removing step within the set cleaning time, the supply of the cleaning liquid may be interrupted during the cleaning. You may leave it. The cleaning liquid supply time and the total amount of liquid to be supplied at one time may be determined according to the liquid supply system, the plate making conditions, the degree of adherence of the removed substances, etc., and the supply speed may be changed or intermittent supply may be performed.

The cleaning liquid used for cleaning the removing means is discarded together with the removed material removed from the printing plate by the removing means. Since the removed substance may be fixed in the waste system, the used cleaning liquid also has an effect of suppressing this fixing. If the liquid used as the cleaning liquid is a liquid that is originally circulated and reused, it is desirable to replenish at least the replenishing liquid corresponding to the consumption of cleaning.

The electrophotographic lithographic printing plate from which the photoconductive layer solubilized by the removing means has been removed is in the removing step, and the plate surface is washed with a small amount of the above-mentioned treatment liquid or rinsing liquid if desired, and then in the rinsing treatment step. Then, a rinse liquid is supplied to completely remove the slightly removed substances remaining on the plate. As the rinse liquid supply method in the rinse treatment process, a conventionally known liquid supply mechanism such as shower, high pressure spray, dip method, etc. can be used, but unlike the elution treatment, the rinse treatment remains on the plate promptly with the rinse liquid. It must be possible to completely remove the liquid matter. Therefore, the supply liquid may be directly supplied to the plate surface as long as it has a mechanism capable of suppressing scattering, or the processing liquid may be compressed or supplied together with compressed air. In addition, especially when the liquid flow, liquid pressure, or liquid amount is low, Japanese Patent Publication No. 3-270
The elution promoting member described in Japanese Patent No. 38 may be used for the rinse processing mechanism. The treatment method used in the rinse treatment according to the present invention may be a disposable method or a circulation reuse method, or other methods can be used if desired.

The rinsing solution according to the present invention has a pH adjusted so that the binder resin and the like in the electrophotographic lithographic printing plate photoconductive layer to be subjected to the plate making process will not re-aggregate, and at least as an eluate. The solubilized photoconductive layer has the property of being able to quickly diffuse and dissolve in the liquid. Further, particularly when the rinse liquid is circulated and reused, it is desirable that the liquid pH does not fluctuate at least during plate making, and specifically, it is important to maintain the liquid pH at 11 or less. Therefore, it is desirable to finally contain a compound having an acid dissociation index of at least 7 to 11 (hereinafter, a compound having an acid dissociation index of at least 7 to 11 is simply referred to as a compound).

When the compound has a plurality of dissociation stages, at least one of the acid dissociation indices should be in the range specified in the present invention. Examples of the compound having an acid dissociation index defined in the present invention include “Chemical Handbook. Basic Edition II”, The Chemical Society of Japan, ed., 3rd edition 1984, published by Maruzen Co., Ltd., II-33.
8 to II-342, all can be used.
Among the compounds, amino acids such as aspartic acid, glycine, glutamic acid and salts thereof are particularly preferable. Two or more kinds of these compounds may be mixed and added. Also,
These compounds may be used as a mixture with an appropriate acid or basic compound, or may be used in combination with an appropriate acid or basic compound for pH adjustment or acceleration of dissolution. Particularly when a solution containing these compounds is added later, it is desirable to adjust the pH to 6.0-9.5, more preferably 7.0-8.0 before adding.

Since the compound can be sufficiently rinsed in the early stage of plate making even with a liquid containing no compound,
As the rinse liquid, a liquid containing no compound may be used first, and may be added afterwards to be finally contained in the circulating treatment liquid, or may be added prior to plate making. In the case of post-addition, the pH of the rinse solution is preferably 8.5 to 10.5, more preferably 9.5 to 10.0 at the start of addition. Further, especially when the plate size is constant, the increase in the pH of the rinse liquid is related to the number of plates passed through, unless the areas of the non-image areas are significantly different. Therefore, the compound can be added every fixed number of plates. Even in the case of pre-addition, it can be further added depending on the pH rise of the rinse liquid during multi-plate printing. When this compound is added prior to plate-making, the compound may be added alone or may be previously dispersed or dissolved in water. When using an aqueous solution, a small amount of an organic solvent may be used to accelerate the dissolution. It is desirable that the pH of the rinse solution according to the present invention is maintained in the range of 7.5 to 10.5, and more preferably in the range of 8.0 to 10.0, at least in the compound-containing treatment solution.

It is desirable to further use a preservative and / or a bactericide in the rinse liquid. The amount to be added to the rinse liquid needs to be adjusted depending on the type of preservative and / or bactericide used (bactericidal power), the bacterial species and its amount mixed in the rinse liquid, the rinse liquid exchange period, etc. ~ 10,000
Used in the ppm range. It is desirable that the preservative and / or the bactericidal agent be added to both the circulating reuse liquid and the replenishing liquid thereof during the plate making period, but it is sufficient that they are contained at least in the replenishing liquid.

The electrophotographic lithographic printing plate after 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 contains a polymer compound, a lipophilic substance, a surfactant, and the like, and known reagents can be used for all these reagents.

Finally, the electrophotographic lithographic printing plate, electrophotographic processing step, and processing liquid composition according to the present invention will be described. The electrophotographic lithographic printing plate according to the present invention has a photoconductive layer provided on a conductive support and can form a toner image by a usual electrophotographic development method. As a conductive support for electrophotographic lithographic printing plate, a plastic sheet having a conductive surface, or aluminum, zinc, copper-
Aluminum, copper-stainless steel, chrome-copper, etc. bimetal, chrome-copper-aluminum, chrome-copper-stainless steel, etc. metal plate, etc. are used as a base, and at least the surface on which the photoconductive layer is provided is subjected to a hydrophilic treatment. It was done. Among these substrates, the aluminum plate is preferably used. This aluminum plate may contain aluminum as a main component and a slight amount of a foreign element, and a conventionally known material can be used.

Since the desired surface texture can be provided 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 alkali 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. Mechanical surface roughening methods include ball polishing, brush polishing, blast polishing,
A known method such as a buffing method can be used. The electrochemical graining method includes a method of performing alternating current or direct current in a hydrochloric acid or nitric acid electrolytic solution. In addition, JP-A-54-
As disclosed in Japanese Patent No. 63902, a method in which both are combined 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 anodizing film is preferably 0.10 to 10 g / m ² , more preferably 1.0 to 6.0 g / m ^2. Is preferred.

An electrophotographic lithographic printing plate is obtained by providing a desired electrophotographic photoconductive layer on the surface-treated surface of the support thus obtained. In the photoconductive layer of the electrophotographic lithographic printing plate according to the present invention, known photoconductive compounds can be used alone or in combination of two or more kinds as desired. In the photoconductive layer, a photoconductive phthalocyanine pigment that can obtain desired electrophotographic characteristics with a small amount is advantageously used. In particular, it has excellent practical photosensitivity even in the long wavelength region corresponding to the light source such as laser.
Type metal-free phthalocyanines and titanyl phthalocyanines are preferred.

A binder resin is used in combination with the photoconductive layer of the electrophotographic lithographic printing plate according to the present invention in order to improve the film properties and the adhesiveness to the support. Specific examples of the binder resin include
Styrene / maleic anhydride copolymer, styrene / maleic acid monoalkyl ester copolymer, methacrylic acid / methacrylic acid ester copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer, acrylic acid / methacrylic acid ester copolymer Styrene, methacrylic acid ester, such as polymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, and vinyl acetate / crotonic acid / methacrylic acid ester copolymer,
Acrylic ester, vinyl acetate, vinyl benzoate, etc. and acrylic acid, methacrylic acid, itaconic acid, crotonic acid,
Maleic acid, maleic anhydride, a copolymer with a carboxylic acid-containing monomer such as fumaric acid or an acid anhydride group-containing monomer,
Vinyl acetal resins such as phenol resin, xylene resin, and polyvinyl butyral can be mentioned.

Among these binder resins, a monomer-containing copolymer having an acid anhydride group or a carboxyl group and a phenol resin have high charge retention when used as a photoconductive layer for electrophotographic printing plates, Therefore, it can be advantageously used. The monomer-containing copolymer having an acid anhydride group,
A copolymer of styrene and maleic anhydride is preferred. The monomer-containing copolymer having a carboxyl group is a copolymer of styrene and maleic acid monoester, or a binary copolymer of acrylic acid or methacrylic acid and their alkyl ester, aryl ester or aralkyl ester. Is preferred. Further, a copolymer of vinyl acetate and crotonic acid is also preferable. Among the phenolic resins, particularly preferred are novolak resins obtained by condensing phenol, o-cresol, m-cresol, or p-cresol with formaldehyde or acetaldehyde under acidic conditions. The binder resins may be used alone or in combination of two or more.

The mixing ratio of the photoconductive compound and the binder resin in the photoconductive layer of the electrophotographic lithographic printing plate according to the present invention is
It may be determined so as to satisfy various characteristics such as desired electrophotographic characteristics and plate-making characteristics, but generally, when the content of the photoconductive compound is small, the sensitivity becomes low. It is preferable to use a mixture of 5 parts by weight or more, more preferably 15 parts by weight or more. 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 properties, and further improvement in 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 a cover due to leakage. Conversely, if the thickness is thick, not only accelerates the deterioration of the eluate but also induces side etching during elution. Since good image reproducibility cannot be obtained, 0.5 to 10 μm
Is good, and more preferably 1.5 to 6 μm.

The electrophotographic lithographic printing plate used in the treatment of the present invention can be obtained by coating a photoconductive layer on a conductive support according to a conventional method. In forming 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 in the upper layer, or the content of the photoconductive compound is increased, etc., and the layers are separated into different layers, etc. It is known that the electrophotographic lithographic printing plate prepared by any of the methods can be processed in the processing method of the present invention.

The coating liquid for forming the electrophotographic photoconductive layer is prepared by dissolving and dispersing each component constituting the photoconductive layer in an appropriate solvent, but the photoconductive compound is a component insoluble in the solvent such as phthalocyanine. When used, it is dispersed in an average particle size of 0.4 μm or less, more preferably 0.2 μm or less by a dispersing machine such as a ball mill, a dyno mill, an attritor or a paint shaker. In addition to the photoconductive compound and the binder resin, the photoconductive layer may optionally contain a plasticizer, a surfactant, and the like for the purpose of improving the film properties such as flexibility of the photoconductive layer and the surface state of the coating. You may add the additive of. The concentration of the coating liquid, the viscosity, the solvent used and the mixing ratio thereof are appropriately selected depending on the coating method and the drying conditions. The coating liquid prepared in this manner is applied by spin coating, blade coating, reverse roll coating,
An electrophotographic lithographic printing plate can be obtained by coating and drying on a support by a known method such as dip coating, rod bar coating, spray coating, and extrusion coating.

A toner image can be formed on the electrophotographic lithographic printing plate 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, contact exposure through a transparent positive film, and scanning exposure. The light source for scanning exposure is a He-Ne laser, an argon ion laser, a krypton ion laser, a ruby laser, a YAG laser,
Nitrogen laser, dye laser, excimer laser, GaA
Laser light sources such as semiconductor lasers such as s / 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.) You can do it.

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 development method can form a fine toner image and is suitable for producing a printing plate with good reproducibility. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are possible. However, in the present invention, the advantage of scanning exposure is utilized, so that image exposure is not performed. Toner development is performed by reversal development.
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 developing the electrophotographic lithographic printing plate needs to be composed of at least a resin component having a resist property with respect to the following eluents. As the resin component, methacrylic acid, acrylic acid, and acrylic resins composed of esters thereof, vinyl acetate resins, copolymers of vinyl acetate with ethylene or vinyl chloride, vinylidene chloride resins, vinyl chloride resins, polyvinyl butyral, etc. Vinyl acetal resin, polystyrene, copolymer of styrene and butadiene, methacrylic acid ester, etc., polyethylene, polypropylene and its chloride, polyester resin such as polyethylene terephthalate, polyamide resin, phenol resin, xylene resin, alkyd resin,
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.

[0044]

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 without departing from the object thereof.

Example 1 JIS 1050 aluminum (thickness of 0.3 mm) was heated to 60 ° C.
It was immersed in a 10% sodium hydroxide aqueous solution and etched so that the amount of aluminum dissolved was 6 g / m ² . After washing with water
It was immersed in a 30% aqueous nitric acid solution for 1 minute for neutralization, and then thoroughly washed with water. Next, electrolytic surface roughening was performed in a 3.0% hydrochloric acid aqueous solution 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, and the support for printing plate was prepared by washing with water and drying. After coating the surface-treated surface of the support with a photoshaker for 1 hour with a paint shaker, the photoconductive composition shown in Table 1 was applied by an extrusion coater so that the coating amount of the solid content was 4.3 g / m ^2. It was dried at 3 ° C. for 3 minutes to prepare an electrophotographic lithographic printing plate.

[0046]

[Table 1]

The obtained electrophotographic lithographic printing plate was 400 mm
It was cut into × 550 mm, shielded from light and heated at 50 ° C. for 2 hours, and then cooled to room temperature. This printing plate was charged in a dark place by a corotron so that the surface potential became about +280 V, and then scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positive charge toner (manufactured by Mitsubishi Paper Mills Ltd., ODP- T
The liquid reversal development was performed in W), the toner dispersion medium was removed by drying with cold air, and the toner was further heat-fixed to form a toner image on the photoconductive layer. A plate making process was carried out on the above toner-developed printing plate using a processing apparatus as shown below.

FIG. 1 shows an electrophotographic lithographic printing plate processing apparatus used for the plate making process in this embodiment. The basic configuration of this processing device consists of an eluate supply section (solubilization step), a solubilized photoconductive layer removal discard section (removal step), a rinse section (rinse step), and a protective gum section. By being inserted into the printing plate transport line 1 in the direction of the arrow, it is sandwiched between a pair of rolls and automatically transported, and at the same time used for plate making processing.

The eluate supply section is further provided with an eluate supply pipe 25,
Rectifier plate 26, liquid supply roll 10a, and eluate supply pipe 2
7, the rectifying plate 28, and the liquid supply roll 11a, the eluate supply unit including two liquid supply means, and the squeeze roll pair 12a.
And 12b. The squeeze roll 12a is made of water-repellent synthetic rubber and is engaged with the lower roll 12b by its own weight. Further, the eluate 29 is rectified by the rectifying plate 26 from the eluate supply pipe 25, rectified by the rectifying plate 28 from the eluate supply pipe 27, and supplied to the plate surface via the liquid supply rolls 10a and 11a, respectively. The eluate squeezed by the liquid feed roll pairs 11a and 11b and the squeeze roll pairs 12a and 12b is again collected in the eluate liquid storage tank 3 and reused.

The eluate storage tank 3 is configured such that the plate-making reduction amount of the eluate 29 is replenished with the elution replenisher 30. The eluate replenisher 30 is supplied from the eluate replenisher reservoir 7 through the replenishment pump 62 to the eluate reservoir 3 when the lower limit of the level sensor (not shown) is reached, and is replenished up to the level sensor upper limit. There is.

The solubilized photoconductive layer removing and discarding section is further arranged in order from the upstream side of the printing plate transporting process liquid supplying means 50 and liquid measuring roll 2.
0, and a pre-removal treatment liquid supply unit including the liquid supply roll 13a, a scraping blade 37 that is a removing unit, a backup roll 14, and a backup roll cleaning blade 38.
A solubilized photoconductive layer removing section, a cleaning / removing liquid supplying means including a cleaning / removing liquid supplying nozzle 36 for supplying a rinsing liquid 45 to the scraping blade 37, a processing liquid supplying means 21, a liquid measuring roll 51, and a liquid supplying roll. The post-removal treatment liquid supply unit 15a and the removal waste liquid primary storage tank 4 are provided.

The liquid feed path to the pre-removal treatment liquid supply unit for supplying the treatment liquid to the plate surface prior to the removal by the scraping blade 37 is from the rinse liquid storage tank 5 to the pump 64, the pipe line 96, and the valve 74. A rinse liquid supply path through which the liquid is sent, a pipe 102 and a valve 82 from a treatment liquid storage source (not shown).
Two systems of the external storage liquid processing liquid supply path for sending the liquid via the and 74 are connected, and any of the processing liquids can be supplied by operating the pump 64 and the valve 82. Similarly, the delivery route to the post-removal treatment liquid supply section is
The rinse liquid storage tank 5 includes two systems, that is, a rinse liquid supply path for supplying liquid through the pump 64, a pipe line 96, and a valve 75, and an external storage liquid processing solution supply path.

The amount of liquid supplied to the pre-removal processing liquid supply unit is controlled by the valve 7
4 and the wire diameter of the wire densely wound around the liquid measuring roll 20. Specifically, a plurality of liquid measuring rolls 20 having different wire diameters are prepared, and the desired liquid supply amount is determined by knowing the liquid supply amount measured from the liquid supply roll 13a and the liquid measuring roll 20 in advance. A liquid measuring roll 20 that can be measured is selected. Further adjustment of the liquid supply amount can be performed to a certain degree by pressing the liquid measuring roll 20 against the liquid supply roll 13a. The liquid supply to both rolls 13a and 20 adjusts the opening degree of the valve 74 so that the treatment liquid is uniformly stored in the groove formed by these rolls in the width direction. The liquid supply amount of the post-removal processing liquid supply unit is adjusted in the same manner.

The contact angle of the scraping blade 37 with respect to the plate surface and the degree of pressurization were adjusted so that the contact width with the backup roll 14 was minimized in the range where the removal of the solubilized photoconductive layer was optimally carried out. The removed material scraped off by the scraping blade 37 is temporarily stored in the removal waste liquid primary storage tank 4, but by opening the valve 77, it is discarded to the removal waste liquid secondary storage tank 9 via the pipe 94. It is supposed to be.

Immediately in front of the scraping blade 37, a nozzle scanning means 35 fixed in parallel to the scraping blade 37 by a holding mechanism (not shown) is arranged, and a liquid supply nozzle 36 is fixed to its movable portion. . The cleaning of the scraped portion of the scraping blade 37 is performed by scanning the liquid supply nozzle 36 in parallel with the scraping blade 37 by the nozzle scanning means 35 while the rinse liquid storage tank 5 is pumped by the pump 63 and the valve 7.
6, the rinse liquid 45 is supplied from the tip of the liquid supply nozzle 36 to the contact portion between the scraping blade 37 and the backup roll 14 through the pipe 95, and the scraping blade 37 and the backup roll 14 are cleaned. .

The rinsing portion is disposed above the first liquid supplying portion for supplying the rinsing liquid 45 directly from the rinsing liquid supply pipe 40 to the plate surface and substantially in the middle between the transport rolls 17a and 18a, and the unused liquid is squeezed together with the compressed air. A second liquid supply part supplied from the high-pressure spray 41, three rinse liquid supply pipes 42, 43 for supplying a rinse liquid to the joint part of the three pairs of transport rolls 16, 17, and 18 to rinse the lower surface of the printing plate. , And 44, and a rinse liquid storage tank 5 which is below these liquid supply parts and stores a rinse liquid 45. The rinsing liquid 45 is supplied from the rinsing liquid storage tank 5 through the pump 65 and the pipe line 97 through the rinsing liquid supply pipe 40 at all times during plate making, and is circulated for reuse. The supply of the unused liquid is set by a processing liquid supply control mechanism (not shown) so that the liquid is supplied only while the printing plate is passing through the second liquid supply section.

The protective gum portion comprises a protective gum solution supply pipe 52, a surface roughening solution measuring roll 22, a liquid supply roll 19a and a lower roll 19b, and a protective gum solution 4.
A protective gum solution storage tank 8 for storing 6 and a primary protective gum solution storage tank 6 for receiving an excess of the protective gum solution. The protective gum liquid 46 supplied from the protective gum liquid supply pipe 52 is measured by the surface roughening liquid measuring roll 22 and applied to the printing plate, and after being squeezed by the roll pair 19a and 19b, the protective gum liquid primary It is temporarily stored in the storage tank 6 and is discarded in the removed waste liquid secondary storage tank 9 via the valve 80 and the pipe 99.

For the plate-making process, processing solutions having the compositions shown in Tables 2 to 5 were used. The unused liquid was filled with an unused liquid having the same composition as the rinse liquid. Further, the elution replenisher and the unused liquid were appropriately replenished in the respective liquid storage tanks according to the amount of use reduction.

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

[Table 5]

The liquid to be supplied to the pre-removal treatment liquid supply section is carried out by the treatment liquid supply control mechanism (not shown) after the leading end of the printing plate has been carried into the liquid supply roll 10a and the rear end thereof has carried out the liquid supply roll 13a. Until the liquid is supplied, the liquid is supplied to the liquid supply roll 13a. The supply amount is valve 74 opening and liquid metering roll 2
The wire diameter of 0 was adjusted, and the discharge rate per unit time was set so that 150 ml / m ^{2 was} supplied onto the plate from the transport speed and the plate size. On the other hand, in the post-removal treatment liquid supply unit, the valve 75 was closed and the liquid measuring roll 51 was removed and not used. The liquid supply roll 13a and the lower roll 13b are 0.5
It was adjusted so that both rolls co-rotate while maintaining a non-contact state with all roll sub-components by leaving a gap of mm.

The cleaning of the scraping blade 37 is carried out by a treatment liquid supply control mechanism (not shown) after the trailing edge of the printing plate is carried out from the liquid supply roll 19a and the leading part of the printing plate is carried into the liquid supply roll 10a for 60 seconds. If not, the rinse liquid 45 was supplied by the operation of the pump 63 for substantially 15 seconds. Further, the discharge amount of the unused liquid of the high-pressure spray 41 was adjusted so as to be equal to the reduction amount of the rinse liquid 45 by the supply to the pre-removal treatment liquid supply unit and the scraping blade 37. Under the above-mentioned processing conditions, plate making was continuously carried out for 50 plates at an interval of 50 seconds for plate making, and then the plate making was paused for 1 hour, and plate making was carried out under the repeating conditions of continuous plate making.

As a result, the photoconductive layer was not apparently mixed in the eluate in the eluate supply section, and peeling transfer of the solubilized photoconductive layer component to the squeeze roll 12a was not observed. On the other hand, although the solubilized photoconductive layer component was somewhat dissolved in the rinse liquid supplied to cause occasional peeling transfer of the photoconductive layer component to the liquid supply roll 13a, it was washed by the rinse liquid 45 before the subsequent plate was carried in. Has never been accumulated. In addition, the rinsing liquid 4 is applied before reaching the scraping blade 37.
At least a part of No. 5 was mixed with the solubilized photoconductive layer component, and was almost removed by the scraping blade 37. The fluidity of the blade-removed material was good, and most of the blade-removed material passed through the backup roll 14 and fell down to the removal waste liquid primary storage tank 4 at least before the entry of the subsequent plate after scraping.

When a total of 2000 plates were made by repeating the above plate making conditions, the rinsing liquid became blue, and the rinsing liquid remained without being squeezed out, especially at the edges of the printing plate carried out from the first liquid supply part of the rinse. It looked bluish in order to do so, but when it was carried out from the second liquid supply part, it was bluish,
A printing plate comparable to the initial plate-making product with no elution failure was obtained. In addition, 100th, 500th, 100th
When printing was performed on the 0th and 2000th plates, in the normal printing (5000 sheets), of course, after the printing was completed, the printing plate heated at 50 ° C did not cause printing stains. Good prints were obtained on all printing plates.

Comparative Example 1 In the electrophotographic lithographic printing plate processing apparatus used in Example 1, the valve 74 was closed and the rinse liquid 4 to the processing liquid supply means 50 was supplied.
Plate making was carried out under the same treatment liquid and plate making conditions as in Example 1 except that feeding of No. 5 was not carried out. Incidentally, the rinse liquid equivalent to that consumed in the pre-removal treatment liquid supply section in Example 1 was appropriately discarded from the rinse liquid storage tank 5 to the removal waste liquid secondary storage tank 9 by opening the valve 78 appropriately.

As the plate making continues, the liquid supply roll 13a
The peel transfer of the photoconductive layer component was gradually induced and accumulated on the roll peripheral surface, and when the plate was left as it was after the completion of plate making, the rolls adhered to each other, so that the liquid supply roll 13a had to be washed. On the other hand, the solubilized photoconductive layer component could be removed only slightly by the scraping blade 37. Moreover, the fluidity of the blade-removed material was poor, and in some cases, the scraped-off material was transferred to the plate surface of the subsequent plate and could not be washed and removed even by the rinse treatment. For these reasons, the rinse liquid increased in blueness much faster than in Example 1,
The printing plate carried out from the second rinse liquid supplying section was considerably blue after at least 1000 plate making.

The plate making is further continued to make a total of 2000 plates,
When a plate-making product was selected and printed under the same conditions as in Example 1, printing smear occurred from the 2000th plate in normal printing and from the 1000th plate in the printing plate heated under the same conditions as in Example 1. Then, a good printed matter was not obtained. Printing spots were generated mainly on both ends in the transport direction of the printing plate, which was particularly rich in the rinse liquid and remained on the plate.

Example 2 Table 6 shows the supply amount of the rinse liquid 45 from the liquid supply roll 13a to the plate surface by adjusting the wire diameter of the wire densely wound around the liquid measuring roll 20 and the opening of the valve 74. Example 1 except that the scraping blade 37 was washed only when the supply amount was changed, and the plate was continuously plate-formed for 10 plates and stopped for 10 minutes 5 times to make a total of 50 plates each. Plate-making was carried out under the same plate-making conditions as. The plate-making results are also shown in Table 6. In Table 6, "removed substance adhesion" is an evaluation of the degree of adhesion and deposition of the solubilized photoconductive layer component on the scraping blade 37 and retransfer of the adhered substance to the plate surface.
The "rinse contamination property" represents a relative concentration when the optical concentration of phthalocyanine mixed in the rinse liquid when rinsing without scratching is 100.

[0071]

[Table 6]

As a result, as is clear from Table 6, the amount of the processing liquid (rinse liquid) supplied prior to scraping was 10 ml.
With / m ² (plate making number 1, outside the present invention), the amount of the supply was too small, so that the treatment liquid was not uniformly supplied near both ends in the plate width direction, and the viscosity of the solubilized photoconductive layer component did not decrease so much. Therefore, the scraping blade 37 did not almost scrape only by sliding on the surface of the photoconductive layer as in Comparative Example 1, and even if the scraped scrape was slightly scraped off, the scraped blade hardly fell off from the blade.
In some cases, it could not be washed and removed even by transferring to the plate surface of the subsequent plate and rinsing.

When the supply amount of the processing liquid was increased to 20 ml / m ² (plate making number 2, the present invention), the unevenness of the supply of the processing liquid was almost eliminated, but the viscosity of the solubilized photoconductive layer component was still high. On the other hand, the scraping property was almost good. On the other hand, there was no case where the scraped removed material was transferred to the plate surface of the subsequent plate and could not be washed and removed even by the rinse treatment, but probably because transfer was enough to wash it, the rinsing liquid The phthalocyanine concentration was not so low.

Further, the processing liquid supply rate was increased to 50 ml / m ²
With (plate making number 3, the present invention), a plate making material having substantially the same degree as that of Example 1 was obtained without any problems in the supply of the treatment liquid and the blade scraping property. In addition, a scraping blade 37 after plate making
When the film was removed and observed, a slightly viscous removed product remained on the blade, but no transfer of the removed product to the plate making plate was observed. The rinse stainability was also at a level that was almost satisfactory.

Similarly, the supply amount of the processing liquid is increased to 100
With ml / m ² (plate making number 4, the present invention) or more, the processing liquid supply property and the removed substance depositing property are satisfactory, and the blade scraping property is not visually confirmed to be different depending on the processing liquid supply amount. A plate-making product similar to that in Example 1 was obtained. In particular, if the supply amount of the processing liquid is 300 ml / m ² (plate making number 6, the present invention) or more, there is almost no difference in the rinse stain property from the optical density of phthalocyanine, and the supply amount of the processing liquid is 400 ml / m ²
Even if it was increased to (plate making number 6, outside the present invention), there was no difference including other evaluation items, and as a result, the amount of waste liquid increased only.

Comparative Example 2 In the electrophotographic lithographic printing plate processing apparatus used in Example 1,
The valve 74 is closed to remove the liquid measuring roll 20, and instead, the liquid measuring roll 51 is mounted at a fixed position, and the valve 7 is closed.
No. 5 was opened, and the same amount (150 ml / m ² ) as the rinse liquid 45 supplied in Example 1 was supplied to the printing plate that passed through the scraping blade 37 in the pre-removal treatment liquid supply section for plate making. Is
Plate making was carried out under the same treatment liquid and plate making conditions as in Example 1.

As a result, the rinse liquid supplied through the liquid supply roll 15a was dissolved in the surface layer of the solubilized portion, so that the solubilized photoconductive layer could be removed by the squeeze by the roll pairs 15a and 15b. The solubilized photoconductive layer component was scarcely scraped off by the scraping blade 37 as in Comparative Example 1, so that the rinsing liquid increased in bluishness to the same extent as in Comparative Example 1, and the rinsing second liquid supply after at least 1000 plate-making. The printing plate carried out from the department was quite blue. When this printing plate was printed, there was no problem in normal printing, but Example 1
When the printing plate heated at 50 ° C. was printed again after the completion of the normal printing in the same manner as in (1), the print background was smeared as in Comparative Example 1, and a good printed material was not obtained.

Example 3 In the electrophotographic lithographic printing plate processing apparatus used in Example 1,
Example 1 except that the pipe 102 was connected to the water supply line, the valve 82 was opened, and 150 ml / m ² of tap water was supplied instead of the rinse liquid 45 without operating the pump 64 during plate making.
Plate-making was carried out under the same processing conditions as above. In addition, in the first embodiment, the rinse liquid equivalent to that consumed by being supplied to the pre-removal treatment liquid supply unit is
As in Comparative Example 1, the rinse liquid was properly discarded from the storage tank 5.

As a result, as in Example 1, at least a part of the tap water was mixed with the solubilized photoconductive layer component before reaching the scraping blade 37, and almost all the solubilized product was removed by the scraping blade 37. Was removed. The fluidity of the blade-removed material was good, and most of the blade-removed material passed through the backup roll 14 and fell down to the removal waste liquid primary storage tank 4 at least before the entry of the subsequent plate after scraping. Further, the rinse stainability was similar to that of Example 1, and the rinsing liquid 45 increased in bluish color along with the plate making, but when it was carried out from the second liquid feeding part, it was bluish and comparable to the initial plate-making product. A printing plate was obtained. Plate making 1000 and 20
Printing was performed in the same manner as in Example 1 for the 00 plate,
Similar to Example 1, a good printed matter was obtained even after heating the printing plate.

Example 4 In the electrophotographic lithographic printing plate processing apparatus used in Example 1,
The valve 75 was also opened, the liquid measuring roll 51 was reattached, and 20 ml / m ² of the rinse liquid 45 was supplied to the plate surface after scraping through the liquid supply roll 15a. The amount of the rinse liquid 45 supplied to the plate surface was changed to the amount shown in Table 7, and the plate was made under the same plate making conditions as in Example 2 and evaluated. The plate-making results are also shown in Table 7.

[0081]

[Table 7]

As is clear from Table 7, the rinse stain resistance is improved as the supply amount of the treatment liquid supplied prior to the scraping is increased as in Example 2, but in addition, the plate surface after scraping is improved. A rinse liquid is supplied and washed to form a roll pair 15a.
Since the squeeze is performed by 15 and 15b and the waste is discarded, the rinse contamination is further improved by supplying the rinsing liquid to the plate surface not only in the pre-removal treatment liquid supply unit but also in the post-removal treatment liquid supply unit.

[0083]

As described above, when the electrophotographic lithographic printing plate is treated by the method for treating an electrophotographic lithographic printing plate of the present invention, the solubilized photoconductive layer in the removing step can be surely removed. Not only can a good printing plate be obtained without causing scumming during printing by preventing plate making processing defects, but it also enables stable processing over a long period of time by suppressing liquid deterioration of each processing liquid. By doing so, the frequency of replacement of the processing liquid is greatly reduced, and the burden of waste liquid processing and maintenance management is reduced.
Brings excellent effect.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional configuration diagram of an electrophotographic lithographic printing plate processing apparatus used for carrying out a method for processing an electrophotographic lithographic printing plate of the present invention.

[Explanation of symbols]

 1 Printing Plate Conveying Line 3 Eluent Storage Tank 4 Removal Waste Liquid Primary Storage Tank 5 Rinse Liquid Storage Tank 10a, 11a, 13a, 15a Liquid Supply Roll 20, 51 Liquid Measuring Roll 21, 50 Treatment Liquid Supply Means 29 Eluent 37 Scraping blade 45 rinse liquid

Claims (2)

[Claims] 1. A non-image area photoconductive layer is swollen and solubilized by supplying an eluent to the image forming surface of an electrophotographic lithographic printing plate having a toner image formed on the photoconductive layer, and solubilized by a removing means. After removing the photoconductive layer, in the method of treating the electrophotographic lithographic printing plate which rinses the plate surface with a rinse liquid, the treatment liquid is supplied to the plate surface prior to the removal of the solubilized photoconductive layer by the removing means, A method for treating an electrophotographic lithographic printing plate, wherein the amount of the treatment liquid supplied per unit printing plate area is 20 to 300 ml / m ² . 2. The method for treating an electrophotographic lithographic printing plate according to claim 1, wherein the treatment liquid supplied to the plate surface prior to the removal by the removing means is a rinse liquid.