JPH04212967A - Electrophotographic printing plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a printing plate in which a photoconductive layer is provided on a conductive support. High photoresponsiveness even to long wavelength light sources for electrophotographic printing plates for producing printing plates by removing the photoconductive layer in non-image areas other than the toner image areas after forming a toner image. The present invention relates to an electrophotographic lithographic printing plate having a high printing durability, which can obtain a printing plate with good image resolution, suppress image thinning due to elution, prevent background smearing, and have high printing durability. [Prior Art] In recent years, mechanical image processing technology and large-capacity data
With the establishment of data storage and transmission technology, all image input, correction, editing, layout, page layout, etc. of characters and figures can be controlled by computer, and it can be instantly transferred to terminal plotters in remote locations using high-speed communication networks and satellite communications. An electronic editing system that can output is in operation. Particularly in the field of newspaper printing, where immediacy is the creed, demand for this electronic editing system is high. [0003] However, lithographic offset printing plates known as PS plates, which have been conventionally used in the newspaper printing field, generally have low sensitivity because image formation involves at least a change in the chemical structure of the photosensitizer due to active rays. Plate making is carried out by contact exposure of a silver salt photographic film original plate on which an image has been recorded in advance. Therefore, even in places where electronic editing systems are in operation, images are first output onto silver halide photographic film, and based on this, printing plates are produced indirectly by contact exposure to PS plates. . This is because it is difficult to develop a direct printing plate that is sensitive enough to produce a printing plate within a practical time using the output plotter's light source (e.g., He-Ne laser, semiconductor laser, etc.). Depends on something. [0004] Therefore, an electrophotographic photoreceptor is considered as a photosensitive material having high photosensitivity that can provide a direct printing plate. Conventionally, as printing plate materials using electrophotography, for example, Japanese Patent Publications No. 47-47610, No. 48-18325,
Photoconductive zinc oxide/resin dispersion offset printing plate materials described in Japanese Patent Publication No. 48-40002, Japanese Patent Publication No. 51-15766, and Japanese Patent Publications No. 37-17162 and Japanese Patent Publication No. 38-7758.
No. 41-2426, No. 46-39405, JP-A-50-19509, No. 52-2437, No. 54-
No. 134632, No. 54-145538, No. 55-1
Organic photoconductive compound/binder resin printing plate materials as described in Japanese Patent No. 53948 and No. 57-147656 are known. The former photoconductive zinc oxide/resin dispersion offset printing plate material has a zinc oxide-rich photoconductive layer based on water-resistant and conductive paper, and produces toner images by electrophotography. After formation, the non-image area is moistened with a desensitizing treatment liquid (for example, an acidic aqueous solution containing iron hexacyano salt or inositic hexaphosphate) in order to make it insensitive to fat, and then used for printing. Offset printing plates treated in this way have a printing life of about 10,000 sheets at most due to good print image reproducibility, and if the composition is made with a composition with enhanced desensitization, there are drawbacks such as deterioration of image quality. have Furthermore, since the photosensitive range of photoconductive zinc oxide is from short wavelengths, rose bengal, bromophenol, etc.
Dye sensitizers such as Ruble are used in combination to increase sensitivity, but these do not have a practical photosensitive range at the wavelength of semiconductor lasers (780 nm), and at present they are not capable of drawing with semiconductor lasers. has not been reached in practical terms. On the other hand, in the latter printing plate materials based on organic photoconductive compounds and binder resins, since these electrophotographic photoreceptors are generally provided on aluminum substrates, adhesion between the aluminum substrate and the photoconductive layer is difficult. If it is strong, it is essentially PS
It has printing durability equal to or higher than that of the printing plate. Also, there are already 800
Organic photoconductive compounds having a practical sensitivity of nm or more are known, and the above-mentioned printing plates using these compounds are being put into practical use. A general plate-making method for these electrophotographic printing plates is to form a toner image on an electrophotographic original plate using a photoconductive compound by a known electrophotographic image forming method, and then toner image formation. By treating the non-image area other than the photoconductive layer with a solution containing an alkaline agent or the like, the photoconductive layer in the non-image area is dissolved and removed from the plate (so-called elution), and the plate is made. In particular, elution is different from alkaline development in PS plates, and toner
This method takes advantage of the difference between the alkali solubility of the toner and that of the photoconductive layer, and the photoconductive layer (image area) where the toner is attached is
Although elution is hindered due to the resist properties of
The leakage of the eluate from the side surface of the photoconductive layer, called side etch, also erodes the photoconductive layer in the image area, making it impossible to obtain good fine line reproducibility. On the other hand, if the elution is carried out slightly under-performing, even though it appears that the photoconductive pigment has been eluted without remaining on the support in the non-image area, the residual film will cause background smearing over time during printing. There are cases where Therefore, elution in an alkali-eluting electrophotographic printing plate depends on the toner composition, its development method, selection of eluent formulation, elution processing mechanism, matching of the electrophotographic printing plate photoconductive layer and eluent, and treatment. It is important to pay attention to plate-making processing conditions such as time, and stricter processing is required than for alkaline development in PS plates. In addition, the photoconductive layer satisfies electrophotographic properties such as initial charging potential, sensitivity, and dark decay, and printing properties such as printing durability, and also suppresses side etching while remaining free from stains that cause printing. Prevents film and faithful toner
In order to obtain image reproducibility, it is necessary to select the atomic groups that participate in elution (e.g., carboxyl group, acid anhydride group, phosphonic acid group, sulfonamide group, sulfonimide group), and to check their alkali solubility in the binder resin molecule. The content of atomic groups (ie, the content of monomers containing alkali-soluble atomic groups) and the setting of monomers that are poorly alkali-soluble at least in polymerized form are also very important. In particular, as a binder resin for electrophotographic printing plates, it is known to be superior in electrophotographic properties, plate-making (elution) properties, printing durability (film strength), etc., as disclosed in Japanese Patent Publication Nos. 2-43181 and 2-2- 44065, etc., and which consists of at least one monomer of acrylic ester and/or methacrylic ester and at least one vinyl polymerizable monomer having a carboxyl group. In the case of polymer resins, in addition to the selection of the type of carboxyl group-containing monomer that provides alkali solubility and the design of the constituent content as mentioned above, there are also important considerations in particular from the viewpoint of improving chargeability and controlling film properties. It is also important to select the type of ester in the acrylic ester and/or methacrylic ester. [0010] An object of the present invention is to provide a printing plate in which a photoconductive layer is provided on a conductive support, in which toner is applied to the scanning exposure area by reversal development using an electrophotographic method. Regarding an electrophotographic printing plate for producing a printing plate by performing alkaline elution removal of a photoconductive layer in a non-image area other than a toner image area after forming an image, a) a long wavelength light source, such as a semiconductor laser ( 780 nm) has practical sensitivity even in scanning exposure, b) a printing plate with good image resolution etc. can be obtained, and c)
d) Conventional P with high water retention and no printing stains
An object of the present invention is to provide an electrophotographic lithographic printing plate having a high printing durability equivalent to or higher than that of an S plate. [Means for Solving the Problems] It is an object of the present invention to set the centerline average roughness (Ra) to 0.3 to 0.3 to ensure photoconductive layer adhesion, elution uniformity, and water retention. A conductive support with a surface of 0.8 μm is used as the printing plate substrate, and contains a binder resin and phthalocyanine, an organic photoconductive compound, for its long wavelength photosensitivity, electrophotographic properties, and residual pigment during elution. A toner image is formed on a printing plate coated with a dispersion for forming a photoconductive layer by reversal development in the scan exposed area using an electrophotographic method, and then a non-image area other than the toner image area is formed using an alkaline eluent. In the electrophotographic lithographic printing plate obtained by washing with water after elution and removal of the photoconductive layer, the electrophotographic properties, elution rate, printing durability (film strength), processing solution of the photoconductive layer after solubilization, and Considering the influence on the processing equipment, etc., a) the monomer component constituting the photoconductive layer binder resin is at least -
A vinyl-polymerizable monomer [I] having a COO-R group and a vinyl-polymerizable monomer [I] having a carboxyl group.
b) Among the monomer components constituting the binder resin, R contains 30 mol% or more of a monomer having an atomic group consisting of 2 to 8 carbon atoms, and c ) The total number of carbon atoms (C1) of vinyl groups in the monomers [I] and [II] constituting the binder resin and the total number of carbon atoms constituting R (
It has been found that this can be achieved by an electrophotographic lithographic printing plate using a binder resin having a ratio C2/C1 of 0.4 to 2.8. The conductive support used in the present invention may be a plastic sheet having a conductive surface, impermeable and conductive paper, or a metal plate such as aluminum, and at least a photoconductive layer. The surface on which the surface is provided may be a conductive support having a center line average roughness (Ra) of 0.3 to 0.8 μm. Also, their thickness is 0.0
7 to 2.0 mm, more preferably 0.1 to 0.5 mm. Among these supports, aluminum plates are preferably used. This aluminum plate is mainly composed of aluminum and may contain trace amounts of other elements, and conventionally known and publicly used materials can be used as appropriate. The above center line average roughness is usually expressed as Ra, and is extracted by sampling a portion of measurement length Lm in the direction of the center line, setting the center line of the sampled portion as the X axis, and the direction of vertical magnification as the Z axis. When the curve is expressed as Z=f(x), it is given by the following equation 1, and is expressed in μm. ##EQU1## That is, Ra represents the standard deviation obtained by dividing the area of the portion surrounded by the extraction curve and the center line by the measurement length. The center line average roughness Ra according to the present invention was measured according to the above formula under the conditions of a cutoff value of 0.8 mm and a measurement length of 0.5 mm for surface roughness calculation. The Ra of the surface of the conductive support concerned has a surface shape in the range of 0.3 to 0.8 μm. When Ra is smaller than 0.3 μm, the adhesion with the photoconductive layer becomes weak and the above-mentioned elution and peeling is easily induced. Moreover, when Ra is larger than 0.8 μm, it becomes difficult to form a homogeneous photoconductive layer, and unevenness in electrophotographic properties and elution properties tends to occur. [0016] A more preferable surface shape of the conductive support according to the present invention is Ra = 0.45 to 0.70 μm, pitch of rough pits of 30 to 100 μm, and bearing length (Rtp) defined in ISO 4287/1 of 70 μm. ~85%
It has a rough surface. In order to form these desired surface shapes on the surface of the support on which the photoconductive layer is provided, graining and anodic oxidation may be carried out by known methods. Prior to graining, degreasing with a surfactant or alkaline aqueous solution is carried out, if desired. Graining treatment methods include mechanical surface roughening methods, electrochemical surface roughening methods, chemical surface selective dissolution methods, and the like. As the mechanical surface roughening method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method, a buff polishing method, etc. can be used. Further, as an electrochemical surface roughening method, there is a method in which alternating current or direct current is used in a hydrochloric acid or nitric acid electrolyte. Also, JP-A-5
As disclosed in Japanese Patent No. 4-63902, a method combining both methods can also be used. The substrate whose surface has been roughened in this manner is used after being subjected to an alkali etching treatment and a neutralization treatment, if necessary. The substrate subjected to the above treatment is anodized to form an oxide film on its surface. As the electrolyte used in the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or a mixed acid thereof is used, and the concentration thereof is appropriately determined depending on the type of electrolyte. Although the anodizing treatment conditions cannot be specified as they vary greatly depending on the electrolyte used, the amount of anodic oxidation film is preferably in the range of 0.10 to 10 g/m2, and more preferably in the range of 1.0 to 6.0 g/m2. is suitable. An intermediate layer may be provided between the conductive support and the photoconductive layer, if necessary, in order to improve adhesiveness and electrophotographic properties. An electrophotographic photoreceptor can be obtained by providing a desired electrophotographic photoconductive layer on the conductive support thus obtained. Phthalocyanine is used as the photoconductive compound used in the photoconductive layer according to the present invention. Phthalocyanine is disclosed in Japanese Patent Publications No. 40-2780, No. 45-8102, No. 45-11021, No. 46-42511, No. 4
No. 6-42512, No. 48-163, No. 49-175
No. 35, No. 50-5059, and JP-A-64-569
No. 64-17066, No. 64-45474, JP-A No. 1-144057, No. 1-153757, No. 1
-217362, 1-221459, 1-25
No. 2967, No. 1-285952, No. 1-31255
No. 1, No. 2-8256, No. 2-16570, and the like, the photoconductive phthalocyanine pigments have a central metal of lithium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, cadmium,
Barium, mercury, aluminum, indium, lutetium, titanium, tin, hafnium, lead, vanadium, antimony, chromium, molybdenum, manganese, iron, cobalt,
Nickel, rhodium, palladium, osmium, and platinum, or metal-free materials containing hydrogen instead of metal are known. Furthermore, various different crystal forms of metal and metal-free phthalocyanine are known as determined by X-ray crystal diffraction measurements. Among these, α type, β type, γ type, π type,
Metal-free phthalocyanine such as τ type, χ type, and ε type, copper phthalocyanine such as α type, β type, γ type, ε type, and η type, titanyl (TiO) phthalocyanine such as α type and β type, magnesium Metal phthalocyanines such as phthalocyanine and halogenoaluminum phthalocyanine are preferred, and χ-type metal-free phthalocyanine which has photosensitivity even in the long wavelength region corresponding to light sources such as He-Ne lasers and semiconductor lasers; Titanyl phthalocyanine is preferred. [0022] At least the average particle size of these particles in the photoconductive layer coating solution is determined by the electrophotographic properties after the photoconductive layer is formed.
In view of various properties such as residual eluted pigment, it is important to disperse the pigment to a size of 0.4 μm or less, more preferably 0.2 μm or less. In carrying out the present invention, the photoconductive compound is not limited to the above-mentioned phthalocyanine, and if desired, conventionally known photoconductive compounds may be used in combination. The photoconductive layer for an electrophotographic printing plate according to the present invention contains at least a binder resin in addition to the above-mentioned phthalocyanine. In the electrophotographic photoconductive layer according to the present invention, it is necessary to finally remove the non-image area photoconductive layer, but this step depends on the solubility of the photoconductive layer in the eluent and the resistivity of the toner image with respect to the eluent. Although it is determined by the relative relationship between body [I] and a vinyl polymerizable monomer having a carboxyl group [II] 10 to 60
b) Among the monomer components constituting the binder resin, R contains 30 mol% or more of a monomer having an atomic group consisting of 2 to 8 carbon atoms, and c) the binder resin The total number of carbon atoms of the vinyl groups in the constituent monomers [I] and [II] (C
1) and the total number of carbon atoms (C2) constituting R: the ratio C
Preferably, the polymer compound has a ratio of 2/C1 of 0.4 to 2.8 and is soluble or easily dispersible in the eluent described below. When C2/C1 is less than 0.4, electrophotographic properties such as chargeability and dark decay deteriorate when this resin is used alone, and when used in combination with a binder resin that improves electrophotographic properties, the homogeneity of elution is disrupted and printing It becomes easy to induce scumming, etc. Conversely, when C2/C1 is greater than 2.8, although the electrophotographic properties are improved, the elution rate becomes slow (particularly when R is 4 or less) or the binder resin becomes soft, making it unsuitable for high printing durability. In the present invention, a particularly preferable range of C2/C1 is 1.0 to 2.
It is 4. [0024] Vinyl polymerizable monomer [I] having at least -COO-R group in the constituent monomer according to the present invention
and a vinyl polymerizable monomer having a carboxyl group [
Specific examples of the binder resin containing styrene/maleic acid monoester copolymer, methacrylic acid/methacrylic acid ester copolymer, methacrylic acid/acrylic acid ester/methacrylic acid ester copolymer, styrene/methacrylic acid ester copolymer, etc. Acid/methacrylic acid ester copolymer, acrylic acid/methacrylic acid ester copolymer, styrene/acrylic acid/methacrylic acid ester copolymer, vinyl acetate/crotonic acid copolymer, vinyl benzoate/crotonic acid copolymer, Methacrylic esters such as vinyl acetate/crotonic acid/methacrylic ester copolymers, acrylic esters, vinyl acetate, vinyl benzoate, etc. and carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, etc. Copolymers with acid-containing monomers or dibasic acid monoester-containing monomers, and in addition, styrene, methacrylic acid amide, vinyl pyrrolidone, acryloylmorpholine, phenolic hydroxyl group, sulfonic acid group, sulfonamide copolymers containing a monomer having a sulfonimide group or a sulfonimide group. The monomer constituting the binder resin according to the present invention contains an ester monomer having 2 to 8 carbon atoms and R in [I]. When R is methyl having 1 carbon number, it is difficult to balance electrophotographic properties such as chargeability and dark decay, and elution rate (tolerance) within the desired range, at least when the ester monomer is used alone. On the other hand, if all R's have carbon atoms of 9 or more, the printing durability (film strength) and elution rate will decrease, and the solvent used in the coating solution will be limited or will not dissolve. Therefore, in the present invention, the number of carbon atoms constituting R in the monomer [I] is 1 or 9.
The above ester monomers may be contained in the present binder resin, but the content is 60 mol% in terms of the number of moles of the constituent monomers.
The content is preferably 40 mol% or less, and more preferably 40 mol% or less. The number of carbon atoms constituting R in the vinyl polymerizable monomer [I] having a -COO-R group according to the present invention is 2.
Examples of R that is 8 include vinyl (specific monomers include vinyl acetate, vinyl benzoate, etc.), ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl. , 2-methyl-1-propyl, 2-methyl-2-propyl, 1-pentyl, 2-pentyl, 3
-pentyl, 2-methyl-1-butyl, 3-methyl-1
-butyl, 3-methyl-2-butyl, 1-hexyl, 2
-hexyl, 3-hexyl, 2-methyl-1-pentyl, 2-ethyl-1-butyl, 4-methyl-2-pentyl, 1-heptyl, 2-heptyl, 3-heptyl, 4-heptyl, 3-ethyl -3-pentyl, 1-octyl, 3
-octyl, 4-octyl, 2-ethyl-1-hexyl, cyclohexyl, methylcyclohexyl, phenyl,
Benzyl, o-tolyl, 2-chloroethyl, 3-chloropropyl, pentachlorophenyl, 2-hydroxyethyl, 2-hydroxypropyl, 2-ethoxyethyl,
2-butoxyethyl, glycidyl, furfuryl, tetrahydrofurfuryl, trifluoroethyl, 1,1,3-
Examples thereof include aliphatic and aromatic hydrocarbons such as trihydroperfluoropropyl and 1,1,5-trihydroperfluoropentyl, and halogen-, hydroxy-, alkoxy- and aryloxy-substituted derivatives thereof. Among these, groups having an aromatic ring in R have excellent electrophotographic properties, particularly in initial charging potential, but the elution rate is extremely slow; however, if R is an alkyl group, electrophotographic lithographic printing plates In order to have excellent balance as a binder resin for a photoconductive layer, it is preferable that the binder resin according to the present invention does not contain an aromatic ring in R. In the binder resin according to the present invention, in order to comprehensively satisfy various properties as a photoconductive layer of an electrophotographic printing plate, it is particularly preferable that R has 4 to 8 carbon atoms. In the present invention, particularly preferred vinyl-polymerizable monomer-containing copolymers having -COO-R groups include acrylic acid or methacrylic acid and their alkyl esters, aryl esters, or aralkyl esters. A copolymer of two or more of these is preferred. The binder resin according to the present invention contains at least a -COO-R group in its structural unit (
As long as it contains the ester) monomer [I] and the carboxyl group-containing monomer [II], it may be used alone or in combination of two or more. In addition, for the purpose of improving the electrophotographic properties, elution properties, printing durability, etc. of the binder resin alone according to the present invention, all the constituent monomers are carboxyl groups and -C
A type of binder resin that does not contain an OO-R group or a binder resin whose constituent elements are monomers in which R is not within the range of the present invention is mixed with the binder resin according to the present invention to the extent that it does not become the main component. It may also be used as Examples of the binder resin that does not contain monomers [I] and [II] include styrene/maleic anhydride copolymer, methacrylic acid amide, vinylpyrrolidone, phenolic hydroxyl group, and sulfone. Monomers and monomers having acid groups, sulfonamide groups, and sulfonimide groups [I]
Examples include copolymers with monomers not containing [II], phenol resins, xylene resins, and the like. [0030] If the binder resin used in the photoconductive layer according to the present invention has a low molecular weight, the film strength (printing durability) will be poor;
If it is a polymer, the elution rate will be slow, and at the same time, the solubilized binder resin that has flowed into the processing solution will increase the viscosity of the processing solution.
In particular, if a large number of electrophotographic printing plates are intermittently processed by circulating and reusing the processing solution in an automatic machine, the rate at which the eluate permeates into the photoconductive layer in the non-image area will not only be slow, but also ,
The molecular weight is particularly important because defects such as liquid sticking in the liquid supply system and between rolls during a stoppage are likely to occur, and the binder resin used must be appropriately adjusted to advantageously exhibit the desired properties. Must be specified, but generally 8,000 to 15,000
0 is preferable, and 10,000 to 80,000 is more preferable. In addition, from the viewpoint of various electrophotographic properties and dissolution properties, the weight fraction of the monomer [II] having a carboxyl group, which is a constituent monomer of the binder resin, to the entire binder resin is Depending on the type of monomer, generally 10 to 6
The content is preferably 0 mol%, more preferably 20 to 40 mol%. If the molar fraction of the monomer having a carboxyl group to the entire binder resin is high, it will have a negative effect on electrophotographic properties, especially dark decay. It is important to set the molar fraction of the monomer having a carboxyl group to the entire binder resin to be low. The mixing ratio of phthalocyanine and binder resin in the photoconductive layer according to the present invention is such that if the content of phthalocyanine is low, the sensitivity will be low. , more preferably 17 parts by weight or more. However, it is not desirable to use more than 40 parts by weight since further improvement in dispersibility and electrophotographic properties cannot be expected. In addition, if the photoconductive layer is thin, the charge required for toner development cannot be charged, and if it is thick, it not only accelerates the deterioration of the eluate but also induces side etching during elution, resulting in a poor image. 0.10 to 30 μm, more preferably 0.50 to 30 μm.
10 μm is good. The electrophotographic lithographic printing plate according to the present invention can be obtained by coating a photoconductive layer on a conductive support according to a conventional method. In preparing the photoconductive layer, the components constituting the photoconductive layer may be contained in the same layer, or separately contained in two or more layers. For example, the lower layer (support side) may contain easily eluted, There are known methods such as arranging a strongly adhesive binder resin and increasing the phthalocyanine content in the upper layer, and using the layer separately, and it can be produced by any of the methods. The coating solution is prepared by dissolving and dispersing each component constituting the photoconductive layer in an appropriate solvent. Since components insoluble in solvents such as phthalocyanine are used, dispersion using a ball mill, paint shaker, dyno mill, attritor, etc. It is used after being dispersed by a machine to an average particle size of 0.4 μm or less, more preferably 0.2 μm or less. The binder resin and other additives used in the photoconductive layer can be added during or after dispersing the phthalocyanine. The coating solution prepared in this way can be applied by spin coating, blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, spray coating, etc.
An electrophotographic lithographic printing plate can be obtained by coating on a support by a known method such as extrusion coating and drying. Examples of solvents for the coating solution include halogenated hydrocarbons such as dichloromethane and dichloroethane, methanol, ethanol, and
-propanol, 1-butanol, propanediol,
Alcohols such as butanediol, ketones such as acetone, 2-butanone, and cyclohexanone, 2-methoxyethanol, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-(2- Examples include glycol ethers such as ethoxyethoxy)ethanol, cyclic ethers such as oxolane, oxane, and dioxane, and esters such as methyl formate, ethyl acetate, propyl acetate, butyl acetate, and ethyl lactate. . For the photoconductive layer, if necessary,
In addition to the phthalocyanine and binder resin, the flexibility of the photoconductive layer,
Plasticizers, surfactants, and other additives can be added for the purpose of improving film properties such as coating surface condition. [0033] On the photoconductive layer according to the present invention, an overcoat layer that can be dissolved when the photosensitive layer is removed by alkali elution is provided for the purpose of improving electrostatic properties, development properties during toner development, or image properties. I can do it. This overcoat layer may be mechanically matted or a resin layer containing a matting agent. As matting agents, zinc oxide, titanium oxide,
Silica, alumina, zirconia, glass particles, starch, plastic pigments such as polymethyl methacrylate, polystyrene, polyethylene, nylon, phenolic resin, and U.S. Pat. Nos. 2,710,245 and 299
The matting agent described in No. 2101 can be mentioned. The resin used in the resin layer containing the matting agent is appropriately selected depending on the combination with the eluent used. Specifically, gum arabic, glue, gelatin, such as methylcellulose, ethylcellulose, hydroxyethylcellulose
Celluloses such as cellulose, hydroxypropyl cellulose and carboxymethyl cellulose, starch and JP-A-59-5
Modified starch derivatives described in Publication No. 7242, etc., JP-A-62
Cyclodextrins described in JP-A-275782, basic acid monoester derivatives of polysaccharides described in JP-A-63-191693, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polyacrylamide, phenolic resins (especially novolac Examples include polyvinyl butyral (preferably phenolic resin) and the like. Two or more of these may be used in combination. [0034] The electrophotographic lithographic printing plate used in the present invention can be produced by known operations using the above-mentioned electrophotographic photoreceptor. That is, it is charged substantially uniformly in a dark place, and an electrostatic latent image is formed by imagewise exposure. Conventionally known exposure methods include reflective image exposure using a xenon lamp, tungsten lamp, fluorescent lamp, etc. as a light source, contact exposure through a transparent positive film, and scanning exposure using a laser beam, light emitting diode, etc. However, in the present invention, scanning exposure is performed, and the light source and exposure method are He-N.
e-laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, GaAs/GaAlAs
, scanning exposure using a laser light source such as a semiconductor laser such as InGaAsP, or scanning exposure using a light emitting diode or liquid crystal shutter (line printer type using a light emitting diode array, liquid crystal shutter array, etc.) (including a light source). Next, the electrostatic latent image is developed with toner. As a developing method, either a dry developing method (cascade development, magnetic brush development, powder cloud development) or liquid development can be used. In particular, the liquid development method can form fine toner images and is suitable for producing printing plates with good reproducibility. Furthermore, positive/positive development by normal development or negative/positive development by reverse development under the application of an appropriate bias voltage is also possible, but in the present invention, in order to take advantage of the advantages of scanning exposure, the image exposure section is 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, or the like. A printing plate can be prepared by using the toner image thus formed as a resist and removing the photoconductive layer in the non-image area with an eluent. The toner according to the present invention needs to contain a resin component that has resistivity to the eluent. Examples of resin components include methacrylic acid,
Acrylic resins consisting of methacrylic acid esters, vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, vinyl chloride resins, vinylidene chloride resins,
Vinyl acetal resins such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, etc., polyethylene, polypropylene and their chlorides, polyester resins such as polyethylene terephthalate, polyamides such as polycapramide, etc. Examples include resins, phenol resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, and other waxes. [0037] The toner can also contain a dye or a charge control agent within a range that does not adversely affect development or fixing. The electrophotographic lithographic printing plate that has undergone toner development is then treated with a treatment liquid such as an alkaline eluent. The eluent according to the present invention is preferably an aqueous solution containing an alkaline agent and having a buffering capacity around the pH of the solution preparation. The alkaline agent to be contained is of the general formula SiO
Silicates expressed as 2/M2O (M represents an alkali metal atom), alkali metal hydroxides, inorganic alkaline agents such as alkali metal and ammonium salts of phosphoric acid and carbonic acid, ethanolamines, ethylenediamine, propanediamine Organic alkaline agents such as silicates, triethylenetetramine, morpholine, etc., and mixtures thereof can be used, but silicates are particularly advantageous because they exhibit suitable alkaline strength and strong buffering capacity at high pH. used. [0039] The eluate according to the present invention further includes the
Ionic compound described in JP 5-25100, JP-A-5
Water-soluble cationic polymers described in JP-A-5-95946, water-soluble amphoteric polymer electrolytes as described in JP-A-56-142528, neutral salts as described in JP-A-58-75152, JP-A-58-190952 The chelating agent described in Japanese Patent Publication No. 1-177541, the liquid viscosity modifier described in Japanese Patent Application Laid-open No. 1-177541,
Known ingredients such as preservatives and bactericidal agents described in JP-A No. 63-226657, various surfactants, and natural and synthetic water-soluble polymers can be included as necessary. The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but soft water is more preferably used, and ion-exchanged water is advantageously used. In addition, in order to more stably mix and disperse the above components in an amount that does not substantially cause elution in a solution containing the eluate composition excluding the alkaline agents mentioned above, the minimum amount of organic A solvent may also be added. The preferable properties of the silicate used in the eluate of the present invention are SiO2/M2O=0.5 to 8.5 (in terms of moles), more preferably 1.2 to 4.0. When used as an eluate, it is preferable to further add an appropriate amount of an alkali metal hydroxide. In this case, the molar ratio of silicic acid (SiO2) to the total amount of alkali metal oxide (M2O) is preferably in the range of SiO2/M2O=1.2 to 3.6. In addition, the alkaline agent concentration in the eluate is one of the main factors determining the elution rate, and in the present invention, the alkaline agent concentration in the eluate is 0.5 to 5.
It is preferably 0% by weight, more preferably 2 to 40% by weight. The pH of the eluate is 11.5 to 14.0, more preferably 12
．． 0 to 13.5 is good, and p in multi-sheet printing and liquid aging.
When the H changes, it is desirable to add a desired replenisher at appropriate times to improve the elution activity. [0042] If the elution time, that is, the time from when the eluate comes into contact with the printing plate to when it comes into contact with the washing liquid, is too short, it will cause poor elution and scumming during printing, and if it is too long, it will cause thinning of the image. This may result in excessive inflow of the photoconductive layer into the eluate. The elution time according to the present invention is specified by the eluate formulation, but is carried out in the range of 2 to 20 seconds, more preferably in the range of 4 to 15 seconds. The elution processing device that can be used in the present invention preferably has a structure that has at least an elution section and a water washing section, and further has a plate surface protective agent application section, but it is preferable that the lithographic printing plate is automatically conveyed to at least elute. The specifications of each part are not particularly limited, as long as they can be processed by water and rinsing. However, when considering the deterioration of the eluate over time, depending on the method of supplying the eluate to the photoconductive layer surface, a large amount of the solubilized photoconductive layer may flow from the top of the plate into the eluate at the elution area, causing deterioration. Therefore, it is desirable to supply the eluate as softly as possible. As a method of supplying the elution part softly, the liquid discharged from the eluate supply pipe is fed to another member,
For example, it is preferable to uniformly supply the photoconductive layer to the photoconductive layer through a rectifying plate, plate transport upper roll, or the like. The amount of eluate discharged at this time may be the minimum amount that can be uniformly supplied to the printing plate, but it is 1.5 to 1% of the amount of liquid discharged by the printing plate when it is conveyed to the washing section.
00 times, more preferably 5.0 to 50 times. It is better that the amount of eluate carried out is as small as possible, and it is desirable to mechanically adjust it to 10 g/m2 or less. The washing section must have a mechanism capable of supplying a washing liquid onto the plate and quickly and completely removing the solubilized photoconductive layer and excess eluate. The liquid may be directly supplied to the solubilized photoconductive layer as long as the mechanism can suppress scattering, or the elution promoting member described in JP-A-60-76395 may be applied to the washing mechanism. In addition, in the water washing section of the present invention, the solubilized photoconductive layer can be scraped off by bringing a rotating brush into direct contact with the photoconductive layer, but normally the solubilized photoconductive layer can be scraped off mechanically. Its use is undesirable because it can be easily removed without scratching and may accelerate side etching. The washing liquid according to the present invention may be of a disposable type or a circulating reuse type,
Alternatively, other methods can be used as desired. 00
45] It is important for the washing liquid that can be used in the present invention to maintain the pH of the liquid at 10.5 or less, and in order to maintain the pH, the acid dissociation index (pKa
) is desirable to finally contain a compound having the following. This compound (hereinafter, a compound having an acid dissociation index (pKa) of at least 7.0 to 10.5 is simply referred to as a compound) should be thoroughly washed with water at first, even if it does not contain the compound. Because the treatment can be carried out, it is possible to use a solution that does not contain the compound at first as a washing solution and then add it afterwards to make it "finally" included in the washing solution, or it can be added to the washing solution prior to plate making. Also good. In the case of the former (post-addition), it is desirable to start addition when the pH of the washing liquid is in the range of 8.5 to 10.5, more preferably 9.5 to 10.0. In addition, especially if the plate size is constant, the non-image area (eluted area)
As long as the areas do not differ greatly, the increase in pH of the washing liquid is approximately proportional to the amount of plates (number of plates), so the compound according to the present invention can be added every certain number of plates. Even in the case of the latter (first addition), it is possible to add more in accordance with the rise in pH of the washing liquid during multi-plate printing. Further, when adding this compound prior to plate making, the compound may be added alone, or may be used as a predispersed or dissolved compound in water. When preparing an aqueous solution, a small amount of an organic solvent may be added to promote dissolution. In particular, if the compound to be added to the washing liquid is a water-soluble solid, it may be immersed in the washing tank so that it is gradually dissolved by liquid flow and pH fluctuation during printing. The pH of the washing liquid that can be used in the present invention must always be kept at 10.5 or less, but at least the pH of the washing liquid containing compounds is in the range of 7.5 to 10.5.
More preferably, it is desirable to keep it in the range of 8.0 to 10.0. [0046] In those having a plurality of dissociation stages due to the compound added to the washing liquid that can be used in the present invention,
At least one of the acid dissociation index (pKa) is 7.0 to 10
．． It would be good if it was in 5. Examples of compounds to be added to the washing liquid include "Chemistry Handbook. Basic Edition II", edited by the Chemical Society of Japan, 1972.
3rd revised edition, published by Maruzen Co., Ltd., II-338~II-
It is described on page 342, and among these compounds, all compounds having the pKa defined in the present invention can be used. Among these compounds, amino acids such as aspartic acid, β-alanine, glycine, glutamic acid, and salts thereof are particularly preferred. Two or more of these compounds may be added as a mixture, or different compounds may be used for the initial addition and the post addition. In addition, these compounds may be used as a mixture (salt) with an appropriate acid or basic compound, or may be mixed with an appropriate acid or basic compound to make an aqueous solution (aqueous dispersion) in order to adjust the pH and promote dissolution. A basic compound may also be used in combination. In particular, when adding a solution containing these compounds later, the pH thereof should be adjusted to 6.0 to 9.5, more preferably 7.0 to 8.0.
It is desirable to adjust and add the amount. The final amount of these compounds added to the washing solution is 0.04 to 10% by weight, more preferably 0.1 to 10% by weight.
5% by weight is preferred. It is desirable to further use a preservative and/or a bactericidal agent in the washing solution. Known preservatives and bactericidal agents can be used. The amount added to the washing liquid needs to be adjusted depending on the type of preservative and/or bactericidal agent used (sterilizing power), the type of bacteria mixed in the washing liquid, and the amount thereof, but it is usually in the range of 1 to 30,000 ppm. More preferably, it is used in a range of 10 to 10,000 ppm. The electrophotographic lithographic printing plate that has been washed with water is treated with a rinsing liquid containing an acidic substance, if necessary. [0048] The rinsing liquid that can be used in the present invention is as follows:
It is desirable that the pH of the liquid is adjusted so that the binder resin in the photoconductive layer of the electrophotographic lithographic printing plate subjected to the plate-making process does not re-agglomerate. In other words, if the initial pH of the rinsing solution does not at least promote the insolubilization of the binder resin, the binder resin that flows in together with the rinsing solution having a pH higher than neutral will remain in a soluble state at least during the circulation of the printing plate. , thereby preventing the above-mentioned troubles caused by re-insolubilization of the binder resin. However, even if only a small amount of the rinsing liquid flows into the protective gum liquid for the plate surface protection treatment that is normally performed afterwards, if the pH of the rinsing liquid is high, the pH of the protective gum liquid will inevitably rise quickly, and the plate surface will be protected. Since the effect is also attenuated, it is desirable to maintain the pH of the rinsing liquid at 7 or less. [0049] Various test materials can be added to this rinsing liquid in order to adjust the pH of the liquid. In particular, in order to more stably process a large number of electrophotographic lithographic printing plates using an automatic elution machine, etc., it is desirable that the pH of the rinsing liquid does not change during plate making for a large number of plates. It is desirable to contain at least one of water-soluble salts as an agent. As a result, when the rinsing liquid according to the present invention is applied to an electrophotographic lithographic printing plate, the basic components resulting from the eluate remaining on the plate are neutralized, and the non-image areas become more hydrophilic. The electrophotographic lithographic printing plate from which the non-image area photoconductive layer has been removed is treated with a protective gum for the purpose of improving the scratch resistance of the plate surface and desensitizing the non-image area. The protective gum liquid that can be used in the present invention includes polymeric compounds, lipophilic substances,
and a surfactant, and all known reagents can be used. [Examples] The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Also, constituting the binder resin -
Vinyl polymerizable monomer [I] having a COO-R group and vinyl polymerizable monomer [I] having a carboxyl group
The ratio of the total number of carbon atoms (C1) of the vinyl group in [I] to the total number of carbon atoms constituting R (C2) is hereinafter expressed as C2/C.
It is written as 1. Example 1 A JIS1050 aluminum sheet was heated at 60°C with 10% N.
Immersed in aOH aqueous solution, aluminum dissolution amount is 6g/m
It was etched to look like 2. After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize it, and then thoroughly washed with water. Next, 3.
Electrolytic surface roughening was performed in a 0% hydrochloric acid aqueous solution at 35 A/dm2 for 50 seconds, and the surface was washed by immersion in a 20% sulfuric acid aqueous solution at 50°C, followed by water washing. Further, the substrate was anodized in a 20% aqueous sulfuric acid solution to form an aluminum oxide film on the surface, washed with water, and then dried to prepare a support for a printing plate. At this time, the center line average roughness Ra of the surface treated surface of the support was 0.55 μm. The following photoconductive composition containing a binder resin having the composition shown in Table 1 was dispersed on the surface treated surface of the support using a paint shaker for 1 hour, and the solid content was adjusted using an extrusion coater. After coating to give 4.5g/m2,
Dry at 90°C for 5 minutes to create an electrophotographic printing plate (printing plate).
No. 1 to 12) were prepared. Photoconductive layer coating liquid composition: methacrylic acid ester/methacrylic acid copolymer
4 parts by weight χ-type metal-free phthalocyanine (manufactured by Dainippon Ink Co., Ltd., trade name Fa
Stogen Blue 8120)


1 part by weight 1,4-dioxane

70 parts by weight xylene


15 parts by weight 2-propanol

10 parts by weight [Table 1] Note) Me, Et, Bu, 2-EH, and L
au represents methyl, ethyl, 1-butyl, 2-ethylhexyl, and lauryl, respectively, and these are -COO-R
represents R in the vinyl polymerizable monomer [I] having a group. The obtained electrophotographic lithographic printing plate precursor was statically charged with corona at +5.3 kV using an electrostatic copying paper tester SP-428 (manufactured by Kawaguchi Electric Co., Ltd.), and the electrophotographic properties were examined. Ta. After charging the surface potential to about +300 V with a corotron in a dark place, scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positively charged toner (manufactured by Mitsubishi Paper Mills, LOM) was applied. −
Liquid reversal development was performed using ED III) to thermally fix the toner to form a toner image on the photoconductive layer. For the above toner-developed printing plate, use an automatic elution machine as shown below to elute the side etch to about 4 μm on one side using eluent, water washing liquid, rinsing liquid, and protective gum liquid. The time was set and the plate-making process was performed. 1) A drive device that has an automatic elution machine elution tank, followed by a washing tank, a rinsing tank, and a protective gum tank, and conveys the toner-developed electrophotographic printing plate by holding it between rolls; It is an automatic machine that has a device that circulates the processing liquid in each treatment tank in a cycle of storage tank → pump → spray nozzle → storage tank, and a replenishment device for each treatment tank. Showa 60-76395
An elution promoting member (brush roll) as described in the above publication is attached to stir the processing liquid on the plate. 2) Composition of eluate 1 (15 dm3) Sodium silicate aqueous solution (30% by weight of SiO2, SiO
2/Na2O molar ratio 3.0)

28.0
Part by weight Potassium hydroxide

1.5 parts by weight pure water

70.5 parts by weight 3) Washing liquid 1 composition (20 dm3) Sodium dioctyl sulfosuccinate
0.10 parts 2-methyl-3-isothiazolone
0.0
1 part by weight ammonium bicarbonate

0.35 parts by weight pure water

99.54 parts by weight 006
1] 4) Rinse solution 1 composition (10dm3) Succinic acid

0.5 parts by weight phosphoric acid (85% aqueous solution)

0.5 parts by weight decaglyceryl monolaurate
0.05 parts by weight 2-methyl-3-isothiazolone
0.01 parts by weight Sodium hydroxide was added to this to adjust the pH of the solution to 4.7, and the pH was adjusted to 10% by weight with pure water.
The amount was 0 parts by weight. 5) Protective gum liquid 1 composition (8 dm3) Gum arabic

5 parts by weight phosphoric acid (85% aqueous solution)

1 part by weight ethylenediaminetetra (methylene phosphonic acid) 0.5 parts by weight Sodium nitrate

1 part by weight citric acid

0.25 parts by weight decaglyceryl monolaurate
0.1 part by weight 2-methyl-3-isothiazolone
0.01 parts by weight Sodium hydroxide was added to this to adjust the pH of the solution to 4.3, and then the solution was diluted with pure water to a pH of 4.3.
00 parts by weight. Next, using this printing plate, printing was carried out using an offset printing machine (Hamada Star 600 CD). The obtained results are summarized in Table 2. [Table 2] [0065] Printing plate having a binder resin with a C2/C1 ratio of less than 0.4 in the photoconductive layer (printing plate No. 2; this binder resin also has a monomer II content ratio of (outside the scope of the present invention) has electrophotographic properties such that the initial charging potential is low and the dark decay is also poor, making it particularly unsuitable for scanning exposure. Furthermore, the high content of acid functional groups in the resin results in faster elution, but less tolerance for elution. On the other hand, a printing plate having a binder resin with C2/C1 exceeding 2.8 in the photoconductive layer (printing plate N
O. 9) is the print version No. Compared to No. 7, the electrophotographic properties are particularly poor in sensitivity, and the elution becomes slow, leading to smearing of the printing surface. In addition, in this system, the printing plate N
O. Regarding printing durability of No. 9, image thinning occurred. On the other hand, even if C2/C1 is within the range of the present invention, a printing plate (printing plate No. 1; outside the present invention) having a binder resin in which R is only methyl in the photoconductive layer, Although the film became hard, it was brittle, making it difficult to maintain a balance between the elution residual film and the side etch, and the photoconductive layer cracked when installed in a printing machine, resulting in image skipping during printing. Conversely, as R becomes a longer chain, the film becomes more difficult to dissolve and becomes more flexible;
A printing plate having a photoconductive layer containing a binder resin composed of lauryl (carbon number 12) (Printing plate No. 10; outside the present invention)
The elution became slow, the formation of aggregates was observed in the water washing area, and in printing, line thinning occurred as the number of printing sheets increased. Furthermore, even if C2/C1 and R are within the range of the present invention, a printing plate having a binder resin with a high content of carboxyl group-containing monomer [II] in the photoconductive layer (printing plate No. 4; the present invention In the case of (external), there was no balance between side etch and elution rate, especially during elution. Contrary to these printing plates, C2/C1 is within the range of the present invention, the number of carbon atoms constituting R is 2 to 8, and the carboxyl group in the monomer constituting the binder resin is Contains monomer [II] at least 30 to 50 mol%
If the printing plate has a binder resin contained in the photoconductive layer,
It can be seen that the main characteristics required for an electrophotographic printing plate are satisfied. Example 2 During the surface treatment process of the conductive support prepared in Example 1, the electrolytic roughening time was changed to prepare a new printing plate support having the surface shape shown in Table 3. The photoconductive layer coating liquid 7 was applied thereto to obtain an electrophotographic lithographic printing plate. Using these printing plates, an offset printing machine (Hamadastar 600
Printing was done using CD. The printing results are also listed in Table 3. [Table 3] As is clear from Table 3, printing plate No. 1
Sample No. 3 (outside the invention) had poor printing durability, and peeling of the photoconductive layer occurred during printing. Also, print version No. In No. 18 (outside the present invention), the center line average roughness of the surface of the photoconductive layer also increases, so the toner image resolution deteriorates, and during elution, the photoconductive layer cannot be completely eluted into the troughs on the support surface. Printing stains occurred, which was thought to be caused by the remaining on the paper. In addition, the side etch varied greatly and toner fine line skipping occurred in some areas. On the other hand, the print version No. Samples Nos. 14 to 17 were excellent in printing durability and staining on the printed surface, and good printed matter was obtained until the end of printing. Example 3 The following photoconductive layer compositions (coating liquids 13 to 16) were coated on the surface-treated surface of the printing plate support prepared in Example 1 under the same conditions as in Example 1, and electrophotography was performed. A lithographic printing plate was prepared. Note that all of the following χ-type metal-free phthalocyanines are the same as those used in Example 1. Photoconductive layer coating liquid 13 composition (Printing plate No. 19) Butyl methacrylate/butyl acrylate/acrylic acid copolymer (acrylic acid 35 mol%, molecular weight 12,000)

5 parts by weight χ-type metal-free phthalocyanine

1 part by weight 1,4-dioxane
76 parts by weight 2
-propanol

18 parts by weight Note) C2/C1=1.3 [0073] Photoconductive layer coating liquid 14 composition (Printing plate No. 20) Styrene/butyl acrylate/acrylic acid copolymer (molar ratio 45:20:35, molecular weight 12,000)

4 parts by weight χ-type metal-free phthalocyanine
1 part by weight xylene

60 parts by weight 1,4-dioxane

18 parts by weight 2-propanol

17 parts by weight
Note) C2/C1=0.73 Composition of Photoconductive Layer Coating Solution 15 (Printing Plate No. 21) Vinyl benzoate/crotonic acid (molar ratio 75:25, molecular weight 2
．． 50,000) 4 parts by weight χ-type metal-free phthalocyanine

1 part by weight oxolane

80 parts by weight 2-
propanol

15 parts by weight Note) C2/C1=0.75 Photoconductive layer coating liquid 16 Composition (Printing plate No. 22) Benzyl methacrylate/methacrylic acid copolymer (molar ratio 5
0:50, molecular weight 10,000)

4 parts by weight χ-type metal-free phthalocyanine
1 part by weight methyl cellosolve acetate
7
5 parts by weight 2-propanol

20 parts by weight Note) C2/C1=1.7
5 [0076] Each electrophotographic printing plate (printing plate) obtained
NO. Nos. 19 to 22) were toner-developed in the same manner as in Example 1, and all had the same resolution and image quality as the developed printing plates of Example 1. Next, the following eluent was used for the above toner-developed printing plate (other processing solutions were used in Example 1).
(The elution time was set so that the side etch was eluted to about 3 μm on one side.) Eluent 2 composition (for printing plates No. 19 and 20) Sodium silicate aqueous solution (SiO2 min 30% by weight, SiO2
/Na2O molar ratio 2.5)

25.0 parts by weight synthetic hectorite (manufactured by Rapport Industries Ltd., trade name Laponite S)

1.0 parts by weight potassium hydroxide

1.4 parts by weight pure water

72.6 parts by weight [0078] Eluent 3 composition (for printing plates No. 21 and 22) Sodium silicate aqueous solution (SiO2 min 30% by weight, Si
O2/Na2O molar ratio 3.0)

15.0
Parts by weight Sodium silicate aqueous solution (SiO2 min 30% by weight,
SiO2/Na2O molar ratio 3.0)


13.0 parts by weight potassium hydroxide

1.4 parts by weight ethanol

8.0 parts by weight pure water

62.6 parts by weight [0079] As a result, no elution failures such as delayed elution (remaining pigment) in non-image areas were observed in all the printing plates made. In addition, using these printing plates, an offset printing machine (Hamada Star 600
When printing was carried out using CD), good printed matter was obtained on all the printed printing plates, with no staining or image peeling on the printed matter up to at least 100,000 copies. Example 4 JIS1050 aluminum sheet was heated at 60°C with 10%N
Immersed in aOH aqueous solution, aluminum dissolution amount is 6g/m
It was etched to look like 2. After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize it, and then thoroughly washed with water. After that, 2
．． Electrolytic surface roughening was performed for 25 seconds in a 0% nitric acid aqueous solution,
The surface was washed by immersing it in a 20% aqueous sulfuric acid solution at 50°C, and then washing with water. Furthermore, a support for a printing plate was prepared by performing anodization treatment in a 20% aqueous sulfuric acid solution, washing with water, and drying. At this time, the center line average roughness Ra of the treated surface of the support was 0.54 μm. The binder resin (B) used in the photoconductive layer coating liquid 13 of Example 3 and the χ-type metal-free phthalocyanine (P) were applied to the surface treated surface of the support at the weight ratio (P/B) shown in Table 4. ) was dispersed in a paint shaker for 1 hour, and then coated with an extrusion coater to a solid content coating amount of 4.5 g/m2. , and dried at 90° C. for 5 minutes to produce electrophotographic lithographic printing plates (printing plates No. 23 to 28). The obtained printing plate precursor was charged with a corona discharge in a dark place so that the surface potential (V0) was about +300V, and then scanned imagewise was exposed using a semiconductor laser (780 nm). Immediately, liquid reversal development was performed using a positively charged toner (LOM-ED III, manufactured by Mitsubishi Paper Industries, Ltd.), and the toner was thermally fixed. A toner image was obtained with good reproducibility. Furthermore, the sharpness of the image was also good. [0083] These electrophotographic printing plate precursors were tested using an electrostatic copying paper tester SP-428 (manufactured by Kawaguchi Electric Co., Ltd.).
The electrophotographic properties were examined using static corona charging at +5.3 kV. Electrophotographic characteristics include the initial charging potential (V0), the ratio of the surface potential 10 seconds after charging to V0 (dark decay; DD10), and the time it takes for the surface potential before exposure to photoattenuate to 30 V ( Sensitivity; E30), and residual potential after 10 seconds of light irradiation (Vr
) was sought. The results obtained are listed in Table 4. As can be seen from Table 4, as P/B increases, sensitivity and residual potential improve, but dark decay tends to worsen. An increase in residual potential causes toner fog, and a decrease in dark attenuation is undesirable, especially in scanning exposure, which requires time for drawing, because it causes a difference in image line width due to enlargement of the printing plate. In practice, there were no problems as mentioned above, but from Table 4, the P/B ratio was 1/6 to 1, which reasonably satisfied all electrophotographic characteristics.
It turns out that /3 is particularly good. Next, the toner-developed plate was subjected to a plate-making process using an eluent, a washing liquid, and a rinsing liquid as shown below. Eluent 4 Composition: Potassium silicate aqueous solution (SiO2: 20% by weight, Si
O2/K2O molar ratio 3.5)

3
0 parts by weight Sodium hydroxide

1 part by weight pure water

69 parts by weight Washing liquid 2 composition (20 dm3) Sodium dioctyl sulfosuccinate
0.1 part by weight butyl p-hydroxybenzoate
0.01
A solution by dispersing and dissolving parts by weight in pure water to make 100 parts by weight was placed in a washing tank, and 15 ml of a 5 wt % glycine aqueous solution was added every time 10 printing plates (A2 size) were processed after the 100th plate was made.
was added. Rinse solution 2 composition (20dm3) Succinic acid

0.2 parts by weight citric acid

0.3 parts by weight Sorbitan monolaurate
0.05 parts by weight 2-
Methyl-3-isothiazolone
0.01 parts by weight Sodium hydroxide was added to the solution to adjust the pH of the solution to 4.7, and the pH was adjusted to 100 parts by weight with pure water. When plates were made using the above processing solution (elution time was set to 8 seconds), the side etch was about 3 μm on one side, and the variation was slight, and in all the plates made, there was no image area in the non-image area. No malfunctions such as delayed elution (remaining pigment) were observed. Next, when printing was carried out using this printing plate (Printing Plate No. 26), good printed matter was obtained without any staining on the printed matter up to at least 100,000 copies. Example 5 The following photoconductive layer composition was dispersed in a paint shaker for 1 hour on the aluminum oxide surface of the conductive support prepared in Example 4, and then coated with a bar coater, and then heated at 90°C. , and was dried for 5 minutes to prepare an electrophotographic lithographic printing plate. Photoconductive layer coating liquid 22 composition (Printing plate No. 29) Butyl methacrylate/butyl acrylate/acrylic acid copolymer (acrylic acid 30 mol%, molecular weight 15,000)

18 parts by weight titanyl phthalocyanine

4 parts by weight 1,4-dioxane
60 parts by weight 2
-propanol

18 parts by weight Note) C2/C1=1.40 Composition of Photoconductive Layer Coating Liquid 23 (Printing Plate No. 30) 2-
Ethylhexyl acrylate/methacrylic acid copolymer (
methacrylic acid 35 mol%, molecular weight 30,000)

18 parts by weight β-type copper phthalocyanine
4 parts by weight 1,4-
dioxane
6
0 parts by weight 2-propanol

18 parts by weight Note) C2/C1=2.6 Composition of Photoconductive Layer Coating Solution 24 (Printing Plate No. 31) Styrene/butyl acrylate/acrylic acid copolymer (mole ratio 35:25:40, molecular weight 15,000)

18 parts by weight titanyl phthalocyanine
4 parts by weight xylene

60 parts by weight 2-propanol

18 parts by weight Note) C2/C1=
0.77 Photoconductive layer coating liquid 25 composition (Printing plate No. 32) Vinyl benzoate/crotonic acid (molar ratio 80:20, molecular weight 2
．． 50,000) 18 parts by weight β-type copper phthalocyanine

4 parts by weight oxolane

72 parts by weight 2-Furanmethanal

6 parts by weight Note) C2/C1=0.80 0096 Composition of Photoconductive Layer Coating Solution 26 (Printing Plate No. 33) Benzyl methacrylate/methacrylic acid copolymer (molar ratio 5
5:45, molecular weight 20,000)

18 parts by weight titanyl phthalocyanine
4 parts by weight methyl cellosolve acetate
6
0 parts by weight 2-propanol

18 parts by weight Note) C2/C1=1.9
3 The obtained printing plate precursor was charged with corona discharge in a dark place so that the surface potential (V0) was approximately +300V, and then scanned using a He-Ne laser (633 nm). Immediately after image exposure, liquid reversal development was performed using a positively charged toner (LOM-ED III, manufactured by Mitsubishi Paper Industries, Ltd.), and the toner was thermally fixed, resulting in printing plate No. 30-35
Toner images with a resolution of 50 lines/mm were obtained on all photoconductive layers with good reproducibility. Furthermore, the sharpness of the image was also good. Effects of the Invention: By using the electrophotographic lithographic printing plate of the present invention, it has practical sensitivity even in scanning exposure using a He-Ne laser or a semiconductor laser, and image resolution is improved. A good printing plate is obtained, with high water retention and no background smearing on printed matter.
It is possible to provide an electrophotographic lithographic printing plate having high printing durability equivalent to or higher than that of conventional photosensitive lithographic printing plates.

Claims (3)

[Claims] [Claim 1] Center line average roughness (Ra) is 0.3 to 0.
．． A toner image is formed on a lithographic printing plate having a photoconductive layer containing at least phthalocyanine and a binder resin on the surface of a conductive support having a diameter of 8 μm by reversal development in the scanning exposed area using an electrophotographic method. Next, in the alkaline elution type electrophotographic printing plate obtained by eluting and removing the photoconductive layer in the non-image area other than the toner image area with an alkaline eluent and washing with water, a) the monomer constituting the binder resin; Body composition is at least -C
A vinyl polymerizable monomer [I] having an OO-R group,
Vinyl polymerizable monomer having a carboxyl group [II
] 10 to 60 mol%, b) In the monomer components constituting the binder resin, R has 2 to 2 carbon atoms.
c) contains 30 mol% or more of a monomer having an atomic group consisting of 8, and c) the total number of carbon atoms of vinyl groups in monomers [I] and [II] constituting the binder resin (C1) and R The ratio C2/C1 to the total number of carbon atoms (C2) constituting is 0.4 to 2
．． 8. An electrophotographic lithographic printing plate characterized in that 2. The vinyl polymerizable monomers [I] and [II] constituting the binder resin contain at least acrylic acid,
2. The electrophotographic lithographic printing plate according to claim 1, comprising methacrylic acid and an alkyl ester thereof, and containing 40 mol % or more of a monomer having 2 to 8 carbon atoms constituting R in [I]. 3. The phthalocyanine is at least one type of χ-type metal-free phthalocyanine or titanyl phthalocyanine, and the weight ratio (P/B) of the binder resin (B) and the phthalocyanine (P) contained in the photoconductive layer. is 1/6~2/5
The electrophotographic lithographic printing plate according to claim 1 or 2.