JP3084752B2 - Electrophotographic lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing plate comprising a conductive support and a photoconductive layer provided thereon. Electrophotographic lithographic printing plate for producing a printing plate by removing the non-image portion photoconductive layer other than the image portion, has high photoresponsiveness even to a long wavelength light source, The present invention relates to an electrophotographic lithographic printing plate having a high printing durability, a high printing durability, and no image smearing due to elution while suppressing background thinning.

[0002]

2. Description of the Related Art In recent years, mechanical image processing techniques and large-capacity data
By establishing data storage and transmission technology, computer control of image input, correction, editing, layout and page layout of characters and figures, etc., and instantaneously to a remote terminal plotter by high-speed communication network or satellite communication An electronic editing system that can output is running. In particular, the demand for this electronic editing system is high in the field of newspaper printing, which relies on immediacy.

[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 chemical structural change due to actinic radiation of a photosensitive agent. In addition, a silver halide photographic film original plate on which an image has been recorded in advance is subjected to close contact exposure to perform plate making. Therefore, even in a place where the electronic editing system is operating, image output is once performed on a silver halide photographic film, and based on this, a printing plate is produced indirectly by close contact exposure to a PS plate. . This is because it is difficult to develop a direct-type printing plate having a sensitivity high enough to produce a printing plate within a practical time using a light source of an output plotter (for example, a He-Ne laser, a semiconductor laser, or the like). It depends.

Therefore, an electrophotographic photosensitive member is considered as a photosensitive material having high photosensitivity capable of providing a direct printing plate. Conventionally, as printing plate materials using electrophotography, for example, JP-B-47-47610, JP-B-48-18325,
JP-A-48-40002 and JP-A-51-15766, and the offset printing plate material of a photoconductive zinc oxide / resin dispersion system and JP-B-37-17162 and JP-B-38-7758.
Nos. 41-2426, 46-39405, JP-A-50-19509, 52-2437, and 54-
No. 134632, No. 54-145538, No. 55-1
Organic photoconductive compound / binder resin-based printing plate materials as described in JP-A-53948 and JP-A-57-147656 are known.

The former photoconductive zinc oxide / resin dispersion type offset printing plate material has a zinc oxide-rich photoconductive layer on a paper provided with water resistance and conductivity, and has a toner image formed by electrophotography. After the formation, the non-image area is wetted with a desensitizing solution (for example, an acidic aqueous solution containing hexacyanoiron salt or inosit hexaphosphate) in order to make it non-sensitive, and then subjected to printing. Offset printing plates that have been treated in this way have a maximum printing life of about 10,000 sheets from the viewpoint of good print image reproducibility, and suffer from disadvantages such as deterioration of image quality if a composition with enhanced desensitization is used. Have.

[0006] Further, since the photosensitive region of photoconductive zinc oxide is shorter than a short wavelength, usually, rosbengal, bromopheno-
Although the sensitivity is increased by using a dye sensitizer such as Ruble, they do not have a practical photosensitive region at the wavelength of a semiconductor laser (780 nm). Has not reached practical use.

On the other hand, in the latter organic photoconductive compound / binder resin printing plate material, since these electrophotographic photosensitive members are generally provided on an aluminum substrate, the adhesion between the aluminum substrate and the photoconductive layer is reduced. If strong, essentially PS
It has the same or higher printing durability as the plate. Also, already 800
Organic photoconductive compounds having a practical sensitivity of not less than nm are known, and the practical use of the printing plates using these compounds is also in progress.

A general plate making method in these electrophotographic lithographic printing plates is to form an electrophotographic printing original plate using a photoconductive compound on a toner image by a known electrophotographic image forming method, and then form the toner image. The non-image portion other than the non-image portion is treated with a solution containing an alkali agent or the like, whereby the non-image portion photoconductive layer is dissolved and removed (so-called elution) from the plate, thereby making a plate. In particular, the elution is different from the alkali development in the PS plate.
The difference between the alkali solubility of the photoconductive layer and that of the photoconductive layer.
The elution is hindered due to the resist property of the toner, but the photoconductive layer itself at the portion where the toner adheres is not essentially alkali-insoluble (or hardly soluble).
The infiltration of the eluate from the side surface of the photoconductive layer, called a side etch, also erodes the photoconductive layer in the image area, failing to obtain good fine line reproducibility. On the other hand, if the elution is performed in an under-moderation, even though the photoconductive pigment seems to be eluted without apparently remaining on the non-image part support, background stains are generated due to the printing time due to the residual film. May be. Therefore, the elution in the alkali-eluting electrophotographic lithographic printing plate is performed by selecting the toner composition, its development method, the selection of the eluent formulation, the elution processing mechanism, and the matching and processing of the electrophotographic lithographic printing plate photoconductive layer and the eluate. It is important to pay attention to plate making processing conditions such as time, etc., and strict processing is required as compared with alkali development in PS plates. The photoconductive layer also satisfies the electrophotographic properties such as initial charging potential, sensitivity, and dark decay, and the printing properties such as printing durability. Toner that prevents film and is faithful
In order to obtain image reproducibility, selection of atomic groups (for example, carboxyl groups, acid anhydride groups, phosphonic acid groups, sulfonamide groups, and sulfonimide groups) that contribute to elution, their alkali solubility in binder resin molecules, The content of the atomic group (that is, the content of the monomer containing the alkali-soluble atomic group) and the setting of the monomer which becomes insoluble in alkali at least in the polymerization form are also very important.

In particular, Japanese Patent Publication No. 2-43181 discloses that a binder resin for an electrophotographic lithographic printing plate is superior in electrophotographic properties, plate making (elution) properties, printing durability (film strength), and the like.
JP-A-2-44065 and the like, at least one of an acrylic ester and / or a methacrylic ester
In at least two kinds of copolymer resins comprising at least one kind of monomer and at least one kind of vinyl polymerizable monomer having a carboxyl group, as described above, a carboxyl group-containing monomer giving alkali solubility is used. In addition to the selection of the monomer species and the design of the composition content, etc., it is also important to select the ester species in the acrylate and / or methacrylate esters, particularly from the viewpoint of improving the chargeability and controlling the film properties. is there.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing plate having a photoconductive layer provided on a conductive support, wherein a toner image is formed by reversal development on a scanning exposure portion by an electrophotographic method. Thereafter, an electrophotographic lithographic printing plate for producing a printing plate by performing alkali elution removal of the non-image portion photoconductive layer other than the toner image portion, a) using a long wavelength light source, for example, a semiconductor laser (780 nm). It has practical sensitivity in scanning exposure, and b) a printing plate having good image resolution and the like is obtained; c)
D) Conventional P
An object of the present invention is to provide an electrophotographic lithographic printing plate having a high printing durability equal to or higher than that of an S plate.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to provide a photoconductive layer having a center line average roughness (Ra) of 0.3 to 0.8 .mu.m in order to ensure adhesion, elution uniformity and water retention. A photoconductive material containing a binder resin and an organic photoconductive compound, phthalocyanine, based on long-wavelength photosensitivity, electrophotographic properties, and residual pigment during elution, using a conductive support having a surface of On a printing plate coated with the layer forming dispersion liquid, a toner image is formed by reversal development in a scanning exposure part by electrophotography, and then a non-image part photoconductive layer other than the toner image part is eluted with an alkaline eluate. Electrophotographic lithographic printing plate obtained by washing after removal, electrophotographic properties, dissolution rate, printing durability (film strength), and effect on solubilized photoconductive layer processing solution and processing equipment In consideration of the above, a) the binder resin for the photoconductive layer The monomer component to be formed comprises a vinyl polymerizable monomer [I] having at least a -COO-R group and a vinyl polymerizable monomer [II] having a carboxyl group at 10 to 60 mol%. B) in the monomer component constituting the binder resin, R represents 2 to 2 carbon atoms;
At least 30 mol% of a monomer having an atomic group consisting of 8) c) the total of carbon atoms (C1) and R of the vinyl group in the monomers [I] and [II] constituting the binder resin the ratio C2 / C1 of the total carbon atoms (C2) constituting the is from 0.4 to 2.8 der
Thus, it was found that d) an electrophotographic lithographic printing plate using a binder resin having an average molecular weight of 10,000 to 80,000 .

As the conductive support used in the present invention, a plastic sheet having a conductive surface, impermeable and conductive paper, or a metal plate of aluminum or the like is used as a base, and at least a photoconductive layer is used. The surface provided with is a conductive support having a surface having a center line average roughness (Ra) of 0.3 to 0.8 μm. Also, their thickness is 0.0
The thickness is preferably from 7 to 2.0 mm, more preferably from 0.1 to 0.5 mm. Among these supports, an aluminum plate is preferably used. The aluminum plate may contain aluminum as a main component and contain a trace amount of a different element, and conventionally known and publicly available materials can be appropriately used.

The center line average roughness is usually expressed as Ra, a portion having a measured length Lm is extracted in the direction of the center line, the center line of the extracted portion is defined as the X axis, and the direction of the longitudinal magnification is defined as the Z axis.
When the extraction curve is represented by Z = f (x), it is given by the following equation 1 and is expressed in μm.

[0014]

(Equation 1)

That is, Ra represents a standard deviation obtained by dividing the area of the portion surrounded by the extraction curve and the center line by the measured length.
The center line average roughness Ra according to the present invention was measured under the conditions of a cut-off value of 0.8 mm and a measurement length of 0.5 mm in the surface roughness calculation in accordance with the above equation. The surface Ra 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, adhesion to the photoconductive layer becomes weak, and the above-mentioned elution and peeling is easily induced. On the other hand, when Ra is larger than 0.8 μm, it is difficult to form a uniform photoconductive layer, and unevenness in electrophotographic characteristics and elution properties tends to occur.

More preferably, the surface shape of the conductive support according to the present invention is Ra = 0.45 to 0.70 μm, the pit interval between the roughened surfaces is 30 to 100 μm, and the bearing length (Rtp) specified in ISO 4287/1 is 70. To have a rough surface of about 85%.

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 performed by a known method. Prior to the graining treatment, if necessary, a degreasing treatment with a surfactant or an aqueous alkali solution is performed. Graining methods include mechanical surface roughening, electrochemical surface roughening, and chemical surface selective dissolution. As the mechanical surface roughening method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. As the electrochemical surface roughening method, there is a method in which an alternating current or a direct current is used in a hydrochloric acid or nitric acid electrolyte. Further, as disclosed in Japanese Patent Application Laid-Open No. 54-63902, a method combining the two can be used. The substrate thus roughened is used after being subjected to an alkali etching treatment and a neutralization treatment as necessary.

The substrate 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 is used, and the concentration is appropriately determined depending on the type of the electrolyte. The anodizing conditions vary greatly depending on the electrolyte used and cannot be specified unconditionally. However, the amount of anodized film is preferably 0.10 to 10 g / m ² , and more preferably 1.0 to 6.0 g / m ^2. Is suitable.

An intermediate layer may be provided between the conductive support and the photoconductive layer, if necessary, in order to improve the adhesiveness and electrophotographic properties. An electrophotographic photoconductor can be obtained by providing a desired electrophotographic photoconductive layer on the thus obtained electroconductive support.

As the photoconductive compound used for the photoconductive layer according to the present invention, phthalocyanine is used. Phthalocyanines are described in JP-B Nos. 40-2780 and 45-8102.
No. 45-11021, No. 46-42511, No. 46-42512, No. 48-163, No. 49-17
Nos. 535 and 50-5059, and JP-A-64-56.
No. 9, No. 64-17066, No. 64-45474,
JP-A Nos. 1-144057, 1-153775, 1-217362, 1-222159, 1-2
No. 52967, No. 1-258595, No. 1-3125
No. 51, No. 2-8256, No. 2-16570 and the like, wherein the central metal is lysium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, Replaces 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 Metal-free materials containing hydrogen are known. In addition, metal and metal-free phthalocyanine,
A variety of different crystal forms are known by X-ray crystal diffraction measurements.

Of these, α-type, β-type, γ-type, π-type,
Metal-free phthalocyanines such as τ-type, χ-type and ε-type, copper phthalocyanines such as α-type, β-type, γ-type, ε-type and η-type, titanyl (TiO) phthalocyanine such as α-type and β-type, and magnesium Phthalocyanines, and metal phthalocyanines such as halogenoaluminum phthalocyanines are preferable, and He-Ne lasers, χ-type metal-free phthalocyanines having photosensitivity even in a long wavelength region corresponding to light sources such as semiconductor lasers, and Titanyl phthalocyanine is preferred.

The average particle diameter of at least the coating liquid for the photoconductive layer is determined by the electrophotographic properties after the formation of the photoconductive layer,
It is important to disperse the particles to 0.4 μm or less in view of various properties such as the dissolution of the eluted pigment, and more preferably to 0.2 μm or less. In the practice of the present invention, the photoconductive compound is not limited to the above-mentioned phthalocyanine, and a conventionally known photoconductive compound may be used in combination, if desired.

The photoconductive layer for an electrophotographic printing plate according to the present invention contains at least a binder resin in addition to the phthalocyanine. In the electrophotographic photoconductive layer according to the present invention, it is necessary to finally remove the non-image portion photoconductive layer, but this step involves the solubility of the photoconductive layer in the eluate and the resist property of the toner image in the eluate. Is determined by the relative relationship of the two components and cannot be expressed unconditionally. However, in the present invention, a) the monomer component constituting the binder resin is at least -C
A vinyl polymerizable monomer [I] having an OO-R group,
Vinyl-polymerizable monomer having carboxyl group [II]
B) in the monomer component constituting the binder resin, R represents 2 to 2 carbon atoms;
At least 30 mol% of a monomer having an atomic group consisting of 8) c) the total of carbon atoms (C1) and R of the vinyl group in the monomers [I] and [II] constituting the binder resin Has a ratio C2 / C1 of 0.4 to 2.8 with respect to the total number of carbon atoms (C2) , and d) has an average molecular weight of 10,000 to 8,000.
In the range of 0, a polymer compound soluble or easily dispersible in an eluate described later is preferable. When C2 / C1 is smaller than 0.4, the electrophotographic properties such as chargeability and dark decay are deteriorated by using this resin alone, and the homogeneity of elution is lost when a binder resin that improves electrophotographic properties is used in combination. It becomes easier to induce soiling and the like. Conversely, when C2 / C1 is larger than 2.8, the electrophotographic properties are improved, but the elution speed is slow (particularly, R is 4 or less), or the binder resin becomes soft and is not suitable for high printing durability. Particularly preferred in the present invention is C2 /
The range of C1 is 1.0 to 2.4.

According to the present invention, at least the constituent monomers
-COO-R group-containing vinyl polymerizable monomer [I] and carboxyl group-containing vinyl polymerizable monomer [I
Specific examples of the binder resin containing [I] include styrene / maleic acid monoester copolymer, methacrylic acid / methacrylic acid ester copolymer, methacrylic acid / acrylic acid ester / methacrylic acid ester copolymer, and styrene / methacrylic acid. 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 acid esters such as vinyl acetate / crotonic acid / methacrylic acid ester copolymers, acrylic acid esters, vinyl acetate, vinyl benzoate, etc .; and carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, etc. Copolymerization with monomer containing acid or monomer containing dibasic acid monoester And a copolymer containing a monomer having styrene, methacrylamide, vinylpyrrolidone, acryloylmorpholine, phenolic hydroxyl group, sulfonic acid group, sulfonamide group, and sulfonimide group in addition. I can do it.

The monomer constituting the binder resin according to the present invention contains an ester monomer having 2 to 8 carbon atoms constituting R in [I]. When R is methyl having 1 carbon atom, it is difficult to balance the electrophotographic properties such as chargeability and dark decay and the elution rate (tolerance) within a desired range by using at least the ester monomer alone. Conversely, if all of R have 9 or more carbon atoms, the printing durability (coating strength) and the elution rate are reduced, and the solvent used for the coating solution is limited or cannot be dissolved. Accordingly, in the present invention, an ester monomer having 1 or 9 or more carbon atoms constituting R of the monomer [I] may be contained in the binder resin, but the content is not more than It is preferably at most 60 mol%, more preferably at most 40 mol%, in terms of the number of moles of monomer.

The vinyl polymerizable monomer [I] having a -COO-R group according to the present invention has 2 to 2 carbon atoms constituting R.
Examples of R that is 8 include vinyl (examples of this specific monomer include vinyl acetate and vinyl benzoate), 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-toluyl, 2-chloroethyl, 3-
Chloropropyl, pentachlorophenyl, 2-hydroxyethyl, 2-hydroxypropyl, 2-ethoxyethyl, 2-butoxyethyl, glycidyl, furfuryl, tetrahydrofurfuryl, trifluoroethyl, 1,1,3
Aliphatic or aromatic hydrocarbons such as -trihydroperfluoropropyl, 1,1,5-trihydroperfluoropentyl,
And their halogen, hydroxy, alkoxy, aryloxy-substituted derivatives and the like.

Of these, groups having an aromatic ring in R are excellent in electrophotographic properties, especially initial charging potential, but the dissolution rate is extremely slow. However, when R is an alkyl group, electrophotographic lithographic printing plates are used. It is preferable that the binder resin according to the present invention does not contain an aromatic ring in R because the binder resin is excellent in balance as a binder resin for a photoconductive layer. In the binder resin according to the present invention, in order to comprehensively satisfy various properties as an electrophotographic lithographic printing plate photoconductive layer, it is particularly preferable that R has 4 to 8 carbon atoms.

In the present invention, particularly preferred vinyl-polymerizable monomer-containing copolymers having a -COO-R group include:
Binary or more copolymers of acrylic acid or methacrylic acid and their alkyl esters, aryl esters or aralkyl esters are preferred. The binder resin according to the present invention comprises at least a —COO—R group-containing (ester) monomer [I] and a carboxyl group-containing monomer [I
[I] may be used alone or in combination of two or more. Further, for the purpose of improving the electrophotographic properties, elution properties, and printing durability of the binder resin alone according to the present invention, all of the constituent monomers are all carboxyl groups and -COO-.
A type of binder resin containing no R group or a binder resin having a monomer whose R is not within the scope of the present invention is mixed with the binder resin according to the present invention in a range not to be a main component. May be used.

Examples of the binder resin not containing the above monomers [I] and [II] include styrene / maleic anhydride copolymer, methacrylamide, vinylpyrrolidone, phenolic hydroxyl group, sulfone Monomers and monomers [I] having an acid group, a sulfonamide group and a sulfonimide group
And a copolymer with a monomer not containing [II],
And xylene resin.

In the binder resin used for the photoconductive layer according to the present invention, if the molecular weight is low, the film strength (printing durability) is poor.
If it is a polymer, the dissolution rate becomes slow at the same time as the solubilized binder resin flowing into the processing solution increases the viscosity of the processing solution,
In particular, if a large number of electrophotographic lithographic printing plates are intermittently processed by circulating and reusing the processing solution in an automatic machine, not only does the rate of seepage of the eluate into the non-image area photoconductive layer become slower ,
The molecular weight is particularly important since defects such as liquid fixation between the liquid supply system and the roll during a stoppage are more likely to occur, and the molecular weight is suitable for advantageously exhibiting the desired properties in the binder resin used. It is necessary to specify, but generally 8000-15000
0 Preferably, the present invention also 10,000 to 80,000 of
Is used . In addition, from the viewpoints of various electrophotographic properties and elution properties, the weight fraction of the monomer [II] having a carboxyl group, which is a constituent monomer of the binder resin, with respect to the entire binder resin, constitutes the binder resin. Depending on the type of monomer, generally 10
~ 60 mol% is preferable, and 20-40 mol% is more preferable. If the molar fraction of the monomer having a carboxyl group with respect to the entire binder resin is high, it adversely affects the dark decay particularly in the electrophotographic properties, and particularly when the latent image is formed by scanning exposure as in the present invention, It is important to set the molar fraction of the monomer having a carboxyl group to the whole binder resin to be lower.

The mixing ratio of the phthalocyanine to the binder resin in the photoconductive layer according to the present invention is such that the lower the phthalocyanine content, the lower the sensitivity. And more preferably 17 parts by weight or more. However, the use of 40 parts by weight or more is not desirable because no improvement in dispersibility and electrophotographic properties can be expected. On the other hand, when the photoconductive layer is too thin, the charge required for toner development cannot be charged. Conversely, when the photoconductive layer is too thick, not only the deterioration of the eluate is promoted, but also a side etch is induced during the elution to obtain a good image. 0.1 to 30 μm, more preferably 0.50 to 1 μm.
0 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 producing the photoconductive layer, a method of containing the components constituting the photoconductive layer in the same layer, or a method of separately containing two or more layers, for example, a method of easily dissolving into the lower layer (support side), There is known a method in which a strongly-adhesive binder resin is disposed, and the phthalocyanine content is increased in the upper layer, and the layers are separated and used in different layers, and any of these methods can be used. The coating solution is prepared by dissolving and dispersing the components constituting the photoconductive layer in an appropriate solvent.Since components insoluble in solvents such as phthalocyanine are used, ball mills, paint shakers, dyno mills, attritors and the like are used. The particles are dispersed to have 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 the dispersion of phthalocyanine or the like. The coating solution thus prepared is coated on the support by a known method such as spin coating, blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, spray coating, or extrusion coating. To form an electrophotographic lithographic printing plate. Examples of the solvent for the coating solution include halogenated hydrocarbons such as dichloromethane and dichloroethane, methanol, ethanol and 2-
Alcohols such as propanol, 1-butanol, propanediol and butanediol, ketones such as acetone, 2-butanone and cyclohexanone, 2-methoxyethanol and 2-methoxyethylacetate 2-ethoxyethyl acetate, 2- (2-ethoxyethoxy) ethanol
Glycol ethers such as oxolane, oxane,
Cyclic ethers such as dioxane; and esters such as methyl formate, ethyl acetate, propyl acetate, butyl acetate, and ethyl lactate. In the photoconductive layer, if necessary, in addition to the phthalocyanine and the binder resin, the flexibility of the photoconductive layer, for the purpose of improving the film physical properties such as the coated surface state, a plasticizer, a surfactant,
Other additives can be added.

On the photoconductive layer according to the present invention, for the purpose of improving electrostatic characteristics, development characteristics during toner development, or image characteristics, an overcoat layer that can be dissolved when the photosensitive layer is alkali-eluted and removed is provided. Can be done. The overcoat layer may be a mechanically matted one or a resin layer containing a matting agent. As a matting agent, zinc oxide, titanium oxide, silica, alumina, zirconia, glass particles, starch, for example, polymethyl methacrylate, polystyrene,
Examples include plastic pigments such as polyethylene, nylon, and phenolic resin, and matting agents described in U.S. Patent Nos. 2,710,245 and 2,929,101.
The resin used for the resin layer containing the matting agent is appropriately selected depending on the combination with the eluate used. Specifically, gum arabic, glue, gelatin, for example, methylcellulose, ethylcellulose, hydroxyethylcellulose
, Celluloses such as cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, starch, and JP-A-59-5.
No. 7242, etc.
Cyclodextrin described in Japanese Unexamined Patent Publication No. 277582/1991, monoacid derivatives of basic acids of polysaccharides described in Japanese Unexamined Patent Publication No. 63-191693, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polyacrylamide, phenolic resin (particularly novolak) Type phenol resin is preferred). Polyvinyl butyral, etc. These may be used in combination of two or more.

The electrophotographic lithographic printing plate used in the present invention can be produced by a known operation using the above-described electrophotographic photosensitive member. That is, it is charged substantially uniformly in a dark place, and forms an electrostatic latent image by image exposure. Conventionally known exposure methods include a reflection image exposure using a xenon lamp, a tungsten lamp, a fluorescent lamp or the like as a light source, a contact exposure through a transparent positive film, and a scanning exposure using a laser beam, a light emitting diode or the like. However, in the present invention, scanning exposure is performed, and the light source and the exposure method are He-N
e laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, GaAs / GaAlA
Scanning exposure using a laser light source such as a semiconductor laser such as s, InGaAsP, or scanning exposure using a light emitting diode and a liquid crystal shutter (line printer type using a light emitting diode array, a liquid crystal shutter array, etc.) Light source).

Next, the electrostatic latent image is developed by a toner. As the developing method, any of dry developing methods (cascade developing, magnetic brush developing, powder cloud developing) and liquid developing can be used. In particular, the liquid development method is suitable for producing a printing plate having good reproducibility, which can form a toner fine image. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are also possible. However, in the present invention, in order to make use of the advantage of scanning exposure, the image exposure section is required. 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, and solvent fixing. Using the toner image thus formed as a resist, the non-image portion photoconductive layer is removed with an eluent to prepare a printing plate.

It is necessary that the toner according to the present invention contains a resin component having resist properties to the eluate. As the resin component, for example, methacrylic acid,
Acrylic resin comprising methacrylic acid ester, etc., vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, vinyl chloride resin, vinylidene chloride resin,
Vinyl acetal resin such as polyvinyl butyral, polystyrene, copolymer of styrene with butadiene, methacrylic acid ester, polyethylene, polypropylene and its chloride, polyester resin such as polyethylene terephthalate, polyamide such as polycapramid Resins, phenol resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, and other waxes.

The toner may also contain a dye or a charge control agent as long as it does not adversely affect development or fixing. The electrophotographic lithographic printing plate which has been subjected to the toner development is then processed with a processing solution such as an alkaline eluate.

As the eluate according to the present invention, an aqueous solution containing an alkaline agent and having a buffering capacity near the pH of the solution preparation is desirable. As the alkaline agent to be contained, the general formula SiO ₂
/ M ₂ O (M represents an alkali metal atom), inorganic alkali agents such as alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, ethanolamines, ethylenediamine, propane Diamines, triethylenetetramine, organic alkali agents such as morpholine, and mixtures thereof can be used,
In particular, the silicate is advantageously used because it exhibits a suitable alkali strength and a strong buffering capacity at a high pH.

The eluate according to the present invention is further disclosed in
Ionic compound described in JP-A-5-25100;
A water-soluble cationic polymer described in JP-A-5-95946; a water-soluble amphoteric polymer electrolyte described in JP-A-56-142528; a neutral salt described in JP-A-58-75152; Chelating agents described in Japanese Patent Application Laid-Open No. H11-177541, liquid viscosity modifiers described in Japanese Patent Application Laid-Open No. 1-177541, preservatives and bactericides described in Japanese Patent Application Laid-Open No. 63-226657, and various surfactants, natural and synthetic water-soluble Known components such as polymers can be contained as necessary.

The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components. Soft water is more preferably used, and ion-exchanged water is advantageously used. In addition, in a solution containing the eluate composition excluding the alkaline agent, the components are more stably mixed and dispersed in an amount that does not substantially elute, so that the minimum amount of organic components together with the eluate active component is minimized. A solvent may be added and contained.

The preferred properties of the silicate related to the eluate of the present invention are SiO ₂ / M ₂ O = 0.5 to 8.5 (in terms of mol), and the range of 1.2 to 4.0 is more preferable. preferable. When an eluate is used, it is preferable to further add an appropriate amount of an alkali metal hydroxide. At that time, the alkali metal oxide (M ₂
The molar ratio of the silicate (SiO ₂₎ to the total amount of O) is, SiO ₂
The range of / M ₂ O = 1.2 to 3.6 is preferred. Further, the concentration of the alkaline agent in the eluate is one of the main factors determining the elution rate, but in the present invention, it is preferably 0.5 to 50% 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, and in the case of a large number of printing plates or pH fluctuations during the aging of the solution, a desired replenisher is added as needed to improve the elution activity. It is desirable to aim at.

The elution time, that is, the time from the contact of the eluate with the printing plate to the further contact with the washing solution, is short. If it is short, it causes poor elution and background staining during printing. Or excessive flow of the photoconductive layer into the eluate. The elution time according to the present invention is specified by the eluate formulation, and is carried out in the range of 2 to 20 seconds, more preferably in the range of 4 to 15 seconds.

The elution apparatus which can be used in the present invention preferably has at least an elution section and a washing section, and further has a structure having a plate surface protective agent coating section. In addition, it is only necessary to perform a rinsing (washing) process, and the specifications of each part are not particularly limited.
However, considering the deterioration of the eluate over time, the supply of the eluate to the surface of the photoconductive layer depends on the method. It is desirable that the eluate be supplied as softly as possible, since it may accelerate. As a method for softly supplying the elution part, the liquid discharged from the eluate supply pipe is separated by another member,
For example, a system in which the photoconductive layer is uniformly supplied to the photoconductive layer through a rectifying plate, a roll for transporting a plate, or the like is preferable. The discharge amount of the eluate at this time may be the minimum amount that can be uniformly supplied to the printing plate, but is 1.5 to 1 times the amount of the liquid brought out by the printing plate when transported to the washing section.
00 times, more preferably 5.0 to 50 times. It is preferable that the amount of the eluate taken out is as small as possible, and it is desirable to mechanically adjust the amount to be 10 g / m ² or less.

The washing section must have a mechanism capable of completely removing the solubilized photoconductive layer and excess eluate by supplying the washing liquid onto the plate. The liquid may be directly supplied to the solubilized photoconductive layer as long as the mechanism can suppress the scattering, or the elution promoting member described in JP-A-60-76395 may be applied to the water washing mechanism. Further, in the washing section according to the present invention, the solubilized photoconductive layer can be scraped off by directly contacting a rotating brush with the photoconductive layer, but usually, the solubilized photoconductive layer is mechanically scraped. Its use is not desirable because it can be easily removed without performing a process and may accelerate the deterioration of the side etch. The washing liquid according to the present invention may be a disposable method or a circulating reuse method,
Alternatively, other schemes can be used if desired.

It is important that the washing solution that can be used in the present invention keep the solution pH at 10.5 or less.
The acid dissociation index (pK) should be at least 7.0 to 10.5 for retention.
It is desirable to finally include the compound having a). 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) is sufficiently washed with water at least initially even with water containing no compound. Since the treatment can be performed, a liquid containing no compound is used as a washing liquid at first, and may be added later and finally contained in the washing liquid, or may be added to the washing liquid prior to plate making. Is also good. In the former case (post addition), the pH of the washing solution is preferably from 8.5 to 10.5, more preferably from 9.5 to 10.0, at the beginning of the addition. In particular, if the plate size is constant, unless the area of the non-image portion (eluted portion) is largely different, the pH rise of the washing liquid is almost proportional to the amount of printing (number of sheets). Can be added. In the latter case (first addition), it can be further added to the multi-sheet printing in accordance with the rise in the pH of the washing solution. 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 preparing an aqueous solution, dissolution may be promoted with a small amount of an organic solvent. In particular, if the compound to be added to the washing liquid is a water-soluble solid, the compound may be immersed in a washing tank so as to be gradually dissolved by the liquid flow during printing and the pH fluctuation. The pH of the washing solution that can be used in the present invention must always be 10.5 or less, but at least the compound-containing washing solution has a pH in the range of 7.5 to 10.5, and more preferably 8. It is desirable to keep it in the range of 0 to 10.0.

In a compound having a plurality of dissociation stages depending on the compound to be added to the washing solution usable in the present invention,
It is sufficient that at least one of the acid dissociation indices (pKa) is in the range of 7.0 to 10.5. Examples of compounds to be added to the washing solution are described in, for example, "Chemical Handbook. Basic Edition II" edited by The Chemical Society of Japan, 3rd edition revised in 1984, published by Maruzen Co., Ltd., pp. II-338 to II-342. Among them, pKa defined in the present invention
Can be used. Among these compounds, amino acids such as aspartic acid, β-alanine, glycine, and glutamic acid, and salts thereof are particularly preferable. These compounds may be added as a mixture of two or more kinds, or different compounds may be used for the first addition and the second addition. These compounds may be used as a mixture (salt) with an appropriate acid or basic compound, or may be used in an aqueous solution (aqueous dispersion) for pH adjustment and dissolution promotion. A basic compound may be used in combination. In particular, when a solution containing these compounds is added later, it is desirable to adjust the pH to 6.0 to 9.5, more preferably 7.0 to 8.0, and then add.

The final addition amount of these compounds to the washing solution is preferably 0.04 to 10% by weight, more preferably 0.1 to 5% by weight.
% By weight is preferred. It is desirable to further use a preservative and / or a bactericide in the washing liquid. Known preservatives and bactericides can be used. The amount to be added to the washing liquid needs to be adjusted according to the type of preservative and / or bactericide to be used (bactericidal power) and the type of bacteria mixed in the washing liquid and the amount thereof, but usually in the range of 1 to 30,000 ppm, More preferably, it is good to use in the range of 10 to 10000 ppm. The electrophotographic lithographic printing plate that has been subjected to the water washing treatment is treated with a rinsing solution containing an acidic substance as necessary.

The rinsing liquid that can be used in the present invention is:
It is desirable that the pH of the solution is adjusted so that the binder resin in the electrophotographic lithographic printing plate photoconductive layer to be subjected to plate making does not re-aggregate. In other words, unless the initial pH of the rinsing liquid at least promotes the insolubilization of the binder resin, the binder resin flowing in with the washing liquid having a neutral or higher liquid pH at least during the liquid circulation pass is in a solubilized state. Therefore, the above-mentioned trouble due to the re-insolubilization of the binder resin can be prevented. However, since the rinsing liquid flows into the protective gum solution for plate surface protection, which is usually performed after that, even if slightly, if the pH of the rinsing solution is high, the pH of the protective gum solution necessarily rises early, and Since the effect is also attenuated, it is desirable to maintain the pH of the rinsing liquid at 7 or less.

Various test materials can be added to the rinsing liquid in order to adjust the pH of the rinsing liquid. In particular, in order to more stably process a large number of electrophotographic lithographic printing plates with an automatic dissolution machine or the like, it is desirable that the pH of the rinsing solution does not fluctuate during the plate making of at least the rinsing solution. It is desirable to include at least one of a water-soluble salt as an agent. Thereby, when the rinsing solution according to the present invention is applied to an electrophotographic lithographic printing plate, a basic component caused by an eluate remaining on the plate is neutralized, and the non-image portion becomes more hydrophilic.

The electrophotographic lithographic printing plate from which the non-image portion photoconductive layer has been removed is subjected to a protective gum treatment for the purpose of improving the scratch resistance of the plate surface and desensitizing the non-image portion. The protective gum solution that can be used in the present invention includes a polymer compound, a lipophilic substance,
And surfactants and the like, and all of these reagents can be known ones.

[0051]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In addition, constituting the binder resin-
Vinyl polymerizable monomer [I] having a COO-R group and vinyl polymerizable monomer [II] having a carboxyl group
The ratio of the total number of carbon atoms of the vinyl group (C1) to the total number of carbon atoms constituting R (C2) is hereinafter referred to as C2 / C1.

Example 1 JIS1050 aluminum sheet was heated at 60 ° C. and 10% N
immersed in aOH aqueous solution, aluminum dissolution amount is 6 g / m
Etched so as to be ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution for 1 minute to neutralize, and sufficiently washed with water. Next, 3.0
The surface was electrolytically roughened in a 35% aqueous hydrochloric acid solution at 35 A / dm ² for 50 seconds, immersed in a 20% aqueous sulfuric acid solution at 50 ° C. to wash the surface, and then washed with water. Further, anodizing treatment was performed in a 20% sulfuric acid aqueous solution to form an aluminum oxide film on the surface, and the substrate was washed with water and dried to prepare a printing plate support. 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 for 1 hour with a paint shaker, and the solid content was applied with an extrusion coater. After application to 4.5 g / m ² , 9
After drying at 0 ° C for 5 minutes, electrophotographic lithographic printing plate
1-12) were produced.

Composition of coating liquid for photoconductive layer Methacrylic acid ester / methacrylic acid copolymer 4 parts by weight χ type metal-free phthalocyanine (Fastogen Blue 8120, trade name, manufactured by Dainippon Ink Co., Ltd.) 1 part by weight 1,4-dioxane 70 Parts by weight xylene 15 parts by weight 2-propanol 10 parts by weight

[0055]

[Table 1]

Note) Me, Et, Bu, 2-EH, and La
u represents methyl, ethyl, 1-butyl, 2-ethylhexyl, and lauryl, respectively, which represent R in the vinyl polymerizable monomer [I] having a -COO-R group.

The obtained electrophotographic lithographic printing plate precursor was corona-charged at +5.3 kV by a static method using an electrostatic copying paper tester SP-428 (manufactured by Kawaguchi Electric Co., Ltd.), and the electrophotographic characteristics were examined. Was. Also, after charging in a dark place by a corotron so that the surface potential becomes about +300 V, scanning image exposure is performed using a semiconductor laser (780 nm), and a positively charged toner (LOM, manufactured by Mitsubishi Paper Mills, Ltd.) -E
In DIII), liquid reversal development was carried out, and the toner was thermally fixed to form a toner image on the photoconductive layer. Using the above-described toner-developed printing plate, using an automatic dissolution machine as shown below, dissolve the side etch with a dissolution solution, a washing solution, a rinsing solution, and a protective gum solution such that the side etch is dissolved to about 4 μm per side. The plate making process was performed for a set time.

1) Automatic dissolution machine A drive device having a dissolution tank, a subsequent washing tank, a rinsing tank, and a protective gum tank, and for transporting the toner-developed electrophotographic lithographic printing plate in a roll while sandwiching the same, An automatic machine having a device for circulating the processing liquid in each processing tank in a cycle of a storage tank → a pump → a spray nozzle → a storage tank, and a replenishing device for each processing tank. Showa 60-76395
An elution accelerating member (brush roll) as described in Japanese Patent Application Laid-Open Publication No. H10-15064 is attached, and the processing solution on the plate is stirred.

[0059] 2) eluate 1 Composition (15dm ³⁾ aqueous solution of sodium silicate (SiO ₂ minutes 30 wt%, SiO ₂ / Na ₂ O molar ratio of 3.0) 28.0 parts by weight of potassium hydroxide 1.5 parts by weight of pure 70.5 parts by weight of water

3) Washing liquid 1 composition (20 dm ³ ) Na dioctyl sulfosuccinate 0.10 parts by weight 2-methyl-3-isothiazolone 0.01 parts by weight Ammonium hydrogen carbonate 0.35 parts by weight Pure water 99.54 parts by weight Department

4) Rinse solution 1 composition (10 dm ³ ) 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 adjust the solution pH to 4.7, and then adjusted to 100 parts by weight with pure water.

5) Composition of protective gum solution 1 (8 dm ³ ) Arabic gum 5 parts by weight Phosphoric acid (85% aqueous solution) 1 part by weight Ethylenediaminetetra (methylenephosphonic acid) 0.5 parts by weight Sodium nitrate 1 part by weight Citric acid 0.1 part 25 parts by weight Decaglyceryl monolaurate 0.1 parts by weight 0.01 parts by weight of 2-methyl-3-isothiazolone 0.01 parts by weight of sodium hydroxide was added thereto to adjust the pH of the solution to 4.3. Parts by weight were used.

Next, using this printing plate, printing was performed with an offset printing machine (Hamadastar 600 CD).
The results obtained are summarized in Table 2.

[0064]

[Table 2]

A printing plate having a binder resin having a C2 / C1 of less than 0.4 in the photoconductive layer (printing plate No. 2; this binder resin also has a monomer II content outside the scope of the present invention) at the same time With regard to the electrophotographic characteristics, the initial charge potential is lowered and the dark decay is also deteriorated, which is not particularly suitable for scanning exposure. In addition, the elution speed is increased due to the high content of the acid functional group in the resin, but the elution cannot be tolerated. Conversely, the printing plate (printing plate No. 9) having a binder resin having C2 / C1 of more than 2.8 in the photoconductive layer has a particularly poor sensitivity in electrophotographic characteristics as compared with printing plate No. 7. However, in the case of elution, the elution is slowed down, causing the printing background to be stained. Also, in this system, the printing durability of printing plate No. 9 suffered from image thinning probably because the binder resin became softer as C2 / C1 increased.

On the other hand, even when 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 is: Since the film was hard but brittle, it was difficult to balance the residual film remaining with the side etch, and when the film was mounted on a printing machine, the photoconductive layer cracked and image streaks occurred during printing. Conversely, as R becomes longer, the film hardly dissolves and exhibits flexibility, but a printing plate (printing plate No. 10) having a binder resin composed of R in lauryl (C12) in the photoconductive layer. Elution was slow in (outside the present invention), the formation of aggregates was observed in the washing section, and in printing, image thinning occurred according to the number of printings. Also, C
Printing plate having a binder resin having a high content of carboxyl group-containing monomer [II] in the photoconductive layer even if C 1 and R are within the range of the present invention (printing plate No. 4; outside the present invention) Did not achieve a balance between the side etch and the dissolution rate, particularly in dissolution.

Contrary to these printing plates, C2 / C1 is within the scope of the present invention, the number of carbons constituting R is 2 to 8, and the carboxyl group in the monomer constituting the binder resin is It can be seen that a printing plate having a binder resin containing at least 30 to 50 mol% of the contained monomer [II] in the photoconductive layer satisfies the main characteristics required as an electrophotographic planographic printing plate.

Example 2 During the surface treatment step of the conductive support prepared in Example 1, a printing plate support having a surface shape shown in Table 3 was newly prepared by changing the electrolytic surface roughening time. The above-mentioned 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
CD). Table 3 also shows the printing results.

[0069]

[Table 3]

As is clear from Table 3, printing plate No. 13
(Outside of the present invention) was inferior in printing durability, and the photoconductive layer peeled off during printing. In addition, printing plate No. 18 (outside the present invention)
Because the center line average roughness of the surface of the photoconductive layer also becomes large, the toner image resolution is deteriorated, and the elution is considered to be caused by the photoconductive layer remaining in the valley of the support surface without being eluted. Printing background stains occurred. In addition, side etch greatly fluctuated, and toner thin wire jump occurred in a part. On the other hand, printing plates Nos. 14 to 17 were excellent in printing durability and printing stains, and good printed matter was obtained until the end of printing.

Example 3 The following photoconductive layer composition (coating liquids 13 to 16) was applied to the surface-treated surface of the printing plate support prepared in Example 1 under the same conditions as in Example 1, and electrophotographed. A lithographic printing plate was prepared. The following χ-type metal-free phthalocyanines are all the same as those used in Example 1.

Composition of Photoconductive Layer Coating Solution 13 (Printing Plate No. 19) Butyl methacrylate / butyl acrylate / acrylic acid copolymer (acrylic acid 35 mol%, molecular weight 12,000) 5 parts by weight 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

Composition of photoconductive layer coating liquid 14 (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 non-metal 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 liquid 15 (printing plate No. 21) Vinyl benzoate / crotonic acid (molar ratio 75:25, molecular weight 25,000) 4 parts by weight χ-type metal-free phthalocyanine 1 part by weight Oxolan 80 parts by weight Part 2-propanol 15 parts by weight Note) C2 / C1 = 0.75

Composition of photoconductive layer coating liquid 16 (printing plate No. 22) Benzyl methacrylate / methacrylic acid copolymer (molar ratio 50:50, molecular weight 10,000) 4 parts by weight χ-type metal-free phthalocyanine 1 part by weight Methyl cellosolve acetate 75 parts by weight 2-propanol 20 parts by weight Note) C2 / C1 = 1.75

Each of the obtained electrophotographic lithographic printing plates (printing plate N
O. 19 to 22) were subjected to toner development in the same manner as in Example 1. As a result, all had the same resolving power and image quality as the printing plate developer of Example 1. Next, the above-mentioned toner-developed printing plate was subjected to plate making using the following eluate (other processing solutions were the same as in Example 1) (elution time was set so that the side etch was eluted to about 3 μm on one side). ).

[0077] solution 2 composition (for printing plate NO.19 and 20) aqueous solution of sodium silicate (SiO ₂ minutes 30 wt%, SiO ₂ / Na ₂ O molar ratio of 2.5) 25.0 parts by weight of synthetic hectorite (Lapo -Product name: Raponite S) 1.0 parts by weight Potassium hydroxide 1.4 parts by weight Pure water 72.6 parts by weight

[0078] eluant 3 Composition (printing plate NO.21 and 22) aqueous solution of sodium silicate (SiO ₂ minutes 30 wt%, SiO ₂ / Na ₂ O molar ratio of 3.0) 15.0 parts by weight of an aqueous solution of sodium silicate (SiO ₂ minutes 30% by weight, SiO ₂ / Na ₂ O 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

As a result, no elution failure such as elution delay in the non-image area (pigment remaining) was observed in all the printing plates. When printing was performed using these printing plates on an offset printing machine (HAMADASTA-600 CD), at least 100,000 sheets of all the printing plates printed were stained on the printed matter and image peeling was observed. No good printed matter was obtained.

Example 4 JIS 1050 aluminum sheet was heated at 60 ° C. and 10% N
immersed in aOH aqueous solution, aluminum dissolution amount is 6 g / m
Etched so as to be ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution for 1 minute to neutralize, and sufficiently washed with water. afterwards,
Electrolytic surface roughening was performed in a 2.0% aqueous nitric acid solution for 25 seconds, and the surface was washed by immersing in a 20% aqueous sulfuric acid solution at 50 ° C., and then washed with water. Further, the plate was subjected to anodizing treatment in a 20% aqueous sulfuric acid solution, washed with water, and dried to prepare a printing plate support. At this time, the center line average roughness Ra of the surface treated surface of the support was 0.54 μm.

The weight ratio (P / B) shown in Table 4 of the binder resin (B) used in the photoconductive layer coating liquid 13 of Example 3 and the χ-type metal-free phthalocyanine (P) was applied to the surface-treated surface of the support. )) Is dispersed for 1 hour with a paint shaker and applied with an extruder coater to give a solid content of 4.5 g / m ² . rear,
After drying at 90 ° C for 5 minutes, an electrophotographic lithographic printing plate (printing plate N
O. 23 to 28).

The obtained printing plate precursor was charged in a dark place by corona discharge so that the surface potential (V ₀ ) became about +300 V, and then scanning image exposure was performed using a semiconductor laser (780 nm). Immediately, the positively charged toner (Mitsubishi Paper Corp., L
When the toner was heat-fixed by liquid reversal development using OM-ED III), a toner image having a resolution of 50 lines / mm was obtained with good reproducibility on the photoconductive layers of all the prepared plates. The sharpness of the image was also good.

The electrophotographic lithographic printing plate precursor was corona-charged at +5.3 kV by a static method using an electrostatic copying paper tester SP-428 (manufactured by Kawaguchi Electric Co., Ltd.), and the electrophotographic characteristics were examined. Was. The electrophotographic characteristics include the initial charging potential (V ₀ ), the ratio of the surface potential to V ₀ 10 seconds after the charging immediately (dark decay; DD ₁₀ ), and the surface potential before exposure becomes light-decayed to 30 V. Time (sensitivity; E
₃₀ ) and the residual potential (Vr) after 10 seconds of light irradiation. Table 4 shows the obtained results.

[0084]

[Table 4]

As can be seen from Table 4, as P / B increases, sensitivity and residual potential improve, but dark decay tends to deteriorate. An increase in the residual potential causes toner fogging, and a decrease in dark decay is not preferable, particularly in scanning exposure, which requires a long time for drawing, because a large image size causes a difference in image width.
Although there was no problem in practical use as described above, Table 4 shows that the P / B ratio is 1/6 to 1 which satisfies all electrophotographic characteristics moderately.
/ 3 is particularly good.

Next, the plate subjected to the above-mentioned toner development was subjected to a plate making process using an eluent, a washing solution and a rinsing solution as shown below.

[0087] eluant 4 Composition potassium silicate solution (SiO ₂ minutes 20 wt%, SiO ₂ / K ₂ O molar ratio of 3.5) 30 parts by weight of sodium hydroxide 1 part by weight of pure water 69 parts by weight

Rinse solution 2 composition (20 dm ³ ) 0.1 part by weight of sodium dioctyl sulfosuccinate 0.01 part by weight of butyl p-hydroxybenzoate was dispersed and dissolved in pure water to make 100 parts by weight, and the solution was placed in a water washing tank. After the preparation and the plate making for 100 plates, 15 ml of a 5% by weight glycine aqueous solution was added each time the plate (A2 size) was processed for 10 plates.

Rinse solution 2 composition (20 dm ³ ) 0.2 part by weight of succinic acid 0.3 part by weight of citric acid 0.05 part by weight of sorbitan monolaurate 0.01 part by weight of 2-methyl-3-isothiazolone After adjusting the solution pH to 4.7 by adding sodium hydroxide, the solution was adjusted to 100 parts by weight with pure water.

When plate making was performed using the above-mentioned processing solution (elution time was set to 8 seconds), the side etch was about 3 μm on one side and the fluctuation was slight, and the non-image area was found in all the plate-making printing plates. No failure such as elution delay (residual pigment) was observed. Next, when printing was performed using this printing plate (printing plate No. 26), no printed matter was stained on at least 100,000 sheets, and a good printed matter was obtained.

Example 5 The following photoconductive layer composition dispersed in a paint shaker for 1 hour was coated on the aluminum oxide surface of the conductive support prepared in Example 4 with a bar coater, and then coated at 90 ° C. After drying for 5 minutes, an electrophotographic lithographic printing plate was prepared.

Composition of photoconductive layer coating solution 22 (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 60 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 (molar ratio 35:25:40, molecular weight 15,000) 18 parts by weight Titanyl phthalocyanine 4 parts by weight Parts xylene 60 parts by weight 2-propanol 18 parts by weight Note) C2 / C1 = 0.77

Composition of photoconductive layer coating liquid 25 (printing plate No. 32) Vinyl benzoate / crotonic acid (molar ratio 80:20, molecular weight 25,000) 18 parts by weight β-type copper phthalocyanine 4 parts by weight Oxolan 72 parts by weight 6-parts by weight of 2-furanmethanal Note) C2 / C1 = 0.80

Composition of photoconductive layer coating liquid 26 (printing plate No. 33) Benzyl methacrylate / methacrylic acid copolymer (molar ratio 55:45, molecular weight 20,000) 18 parts by weight Titanyl phthalocyanine 4 parts by weight Methyl cellosolve acetate -G 60 parts by weight 2-Propanol 18 parts by weight Note) C2 / C1 = 1.93

The obtained printing plate precursor was charged by applying a corona discharge in a dark place so that the surface potential (V ₀ ) became about +300 V, and then scanned using a He-Ne laser (633 nm). Image exposure and immediate positive charge toner (Mitsubishi Paper Industries, Ltd.)
Liquid development using LOM-ED III)
Was thermally fixed, and a toner image having a resolution of 50 lines / mm was obtained with good reproducibility on all the photoconductive layers of printing plates Nos. 30 to 35. The sharpness of the image was also good.

[0098]

By using the electrophotographic lithographic printing plate of the present invention, the lithographic printing plate has practical sensitivity in scanning exposure with a He-Ne laser or a semiconductor laser and has good image resolution. A printing plate is obtained, the water retention is high and there is no generation of stain on the printed matter,
An electrophotographic lithographic printing plate having a high printing durability equal to or higher than that of a conventional photosensitive lithographic printing plate can be provided.

Claims (2)

(57) [Claims] 1. A center line average roughness (Ra) of 0.3 to 0.
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 thickness of 8 μm, a toner image is formed by reversal development in a scanning exposure portion by electrophotography, and then In an alkali-eluting electrophotographic lithographic printing plate obtained by eluting and removing a non-image area photoconductive layer other than a toner image area with an alkaline eluate and then washing with water, a) a monomer component constituting a binder resin Is at least -C
A vinyl polymerizable monomer [I] having an OO-R group,
Vinyl polymerizable monomer having a carboxyl group [I
B) vinylic polymerizable monomers [I] and [II]
At least acrylic acid, methacrylic acid,
Consists kill ester, the monomer components constituting the c) binder resin, R is 2 carbon atoms
D ) containing at least 40 mol% of a monomer having an atomic group consisting of: d ) the total of carbon atoms (C1) and R Is a ratio C2 / C1 to the total (C2) of the carbon atoms that constitute
An electrophotographic lithographic printing plate, characterized in that: 2. The weight ratio (P / B) of the binder resin (B) and the phthalocyanine (P) contained in the photoconductive layer, wherein the phthalocyanine is at least one of χ-type metal-free phthalocyanine or titanyl phthalocyanine. Is 1/6 to 2/5
The electrophotographic lithographic printing plate according to claim 1, wherein