JPH0451155A - Manufacturing method of electrophotographic printing plate - Google Patents

Abstract

PURPOSE:To obtain the printing plate having the good definition and sharpness of images by specifying the surface roughness of the aluminum oxide surface of a conductive base and the viscosity of a dispersion for forming photoconductive layer. CONSTITUTION:The viscosity of the dispersion of 4 to 10wt.% solid content concn. for forming the photoconductive layer is adjusted within the 5 to 22cps range and this soln. is applied on the conductive base having 0.3 to 0.8 mum center line average height (Ra) in the case of production of the electrophotographic planographic printing plate by providing the conductive base contg. at least phthalocyanine and a binder rein on the conductive base clad with the aluminum oxide. The dispersibility and the coatability of the phthalocyanine are improved in this way and the good definition, etc., of images are obtd. The high-grade printed images are obtd. without generating scumming and plate wearing.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Field of Application The present invention relates to a method for producing an electrophotographic printing plate in which a dispersion for forming a photoconductive layer is applied to a conductive support. The present invention relates to a method for producing an electrophotographic printing plate having improved coating properties, good image resolution, etc. of the produced printing plate, no occurrence of scumming, and high printing durability.

(B) Prior art and its problems In recent years, with the establishment of mechanical image processing technology and large-capacity data storage and transmission technology, image input, correction, and
All editing, layout, page layout, etc. are controlled by computer.
An electronic editing system is in operation that can instantly output data to terminal plotters in remote locations using high-speed communication networks and satellite communications. Particularly in the field of newspaper printing, where immediacy is the creed, demand for this electronic editing system is high.

However, lithographic offset printing plates known as PS plates, which have been conventionally used in the newspaper printing field, have generally low sensitivity because image formation involves at least a change in the chemical structure due to actinic rays of the photosensitizer. Plate making is performed by contact exposure of the recorded silver halide photographic film original plate.

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 with a sensitivity high enough to produce a printing plate within a practical time using the output plotter's light source (eg, He-Ne laser, semiconductor laser, etc.).

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 (printing original plates) using electrophotography, for example, Japanese Patent Publication Nos. 4'7-47610 and 48-18325
Photoconductive zinc oxide/resin dispersion offset printing plate materials described in Japanese Patent Publications No. 48-40002, Japanese Patent Publication No. 51-15766, and Japanese Patent Publications No. 37-17162 and Japanese Patent Publication No. 38-77.
No. 58, No. 41-2426, No. 46-39405,
JP-A-50-1.9509, JP-A No. 52'-2437,
No. 54-134632, No. 54-145538, No. 55-153948, No. 57-147656, No. 5
Organic photoconductive compound/binder resin printing plate materials are known, such as those described in Japanese Patent Publication No. 7-161863.

The former photoconductive zinc oxide/resin dispersion offset printing plate material has a zinc oxide-rich photoconductive layer on a water-resistant and conductive paper base, and after forming a toner image by electrophotography, After wetting the non-image area with a desensitizing treatment solution (for example, an acidic aqueous solution containing iron hexacyano salt or inodite hexaphosphate),
Provided 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 photoconductive zinc oxide is sensitive to short wavelengths, dye sensitizers such as rose bengal and bromophenol blue are usually used in combination to increase sensitivity, but these are at the wavelength of the semiconductor laser (780 nm). It does not have a practical photosensitive range, and at present it has not yet reached the point where it can be drawn with a semiconductor laser.

On the other hand, in the latter organic photoconductive compound/binder resin printing plate materials, these electrophotographic photoreceptors are generally provided on an aluminum substrate, so the aluminum substrate and photoconductive layer are firmly adhered. If so, it essentially has a printing durability equivalent to or higher than that of the PS plate. In addition, organic photoconductive compounds are already known that have practical sensitivity at 800 nm or more.
Practical use of the above-mentioned printing plates using these compounds is also progressing.

These conventional plate-making methods involve forming a toner image using an electrophotographic image forming method, and then treating the non-image area other than the toner image area with a solution containing an alkaline agent or the like to make the plate more transparent. Dissolving the photoconductive layer in the image area (so-called elution)
Furthermore, in general, the excess eluate and the solubilized photoconductive layer are removed from the plate using a washing solution with a pH of at least neutral, and if necessary, a plate protection solution (protective gum solution) is applied. It is coated and made into a plate.

This method of plate making consists of not only the image area or toner image area but also the photoconductive layer below it, so that even if the toner image area is worn out, the function of the photoconductive layer or image area is maintained.
Excellent printing durability.

As a result of further research on these lithographic printing plates,
In these lithographic printing plates, if the surface roughness of the conductive support is too large, halation is likely to occur, which is not only undesirable from the plate-making point of view, such as image resolution and sharpness.
It has been found that the non-image area is not completely eluted, resulting in a defective elution called so-called pigment residue, and when used as a printing plate, it has an undesirable adverse effect on printing suitability, such as staining of the printing surface.

It has also been found that if the surface roughness of the lithographic printing plate conductive support is too small, the adhesion of the photoconductive layer to the support becomes insufficient, resulting in insufficient printing durability.

The present invention further relates to the surface roughness of the aluminum oxide surface of a conductive support and the dispersion for forming a photoconductive layer in a method for producing an electrophotographic lithographic printing plate in which a dispersion for forming a photoconductive layer is applied to a conductive support. As a result of examining the relationship with the viscosity of the liquid, we found that if the viscosity of the photoconductive layer-forming dispersion liquid is absolutely high, coating unevenness will occur regardless of the surface roughness of the conductive support, and coating unevenness will not occur. Even if coating is possible, especially if the surface roughness of the support becomes large, the coating liquid will not fill the valleys and the adhesion between the photoconductive layers of the support will be insufficient, resulting in poor image reproducibility, poor elution, etc. during plate making and printing. This will have a negative impact on suitability, etc.

On the other hand, if the viscosity of the photoconductive layer-forming dispersion is too low, the troughs of the support will be sufficiently filled with the coating liquid, so the greater the surface roughness, the better the adhesion will be. Since the photoconductive layer is provided on a conductive support with a rough surface, the thickness of the photoconductive layer itself is microscopically uneven, and migration of the binder resin is likely to occur during drying of the coating solution. It has been found that unevenness occurs in electrophotographic characteristics such as charging potential, and in thinning of the image due to the running of the eluate from the side surface of the photoconductive layer during elution, which is called side etch.

(C) Object of the Invention The object of the present invention is to provide an electrophotographic lithographic printing plate having a photoconductive layer comprising at least phthalocyanine and a binder resin on a conductive support, which has excellent phthalocyanine dispersibility and eliminates coating streaks. An object of the present invention is to provide a method for producing an electrophotographic printing plate, which can produce a printing plate with improved coating properties without occurrence of coating unevenness and with good image resolution and sharpness.

Another object of the present invention is to provide a method for producing an electrophotographic printing plate that has high printing durability, is free from scumming of printed matter, and has good water retention.

(D) Means for Achieving the Object The above object of the present invention is to provide an electrophotographic lithographic printing plate in which a photoconductive layer containing at least phthalocyanine and a binder resin is provided on a conductive support coated with aluminum oxide. In the manufacturing method, the center line average roughness (Ra) is 0.3 to 0.8
This is achieved by coating a photoconductive layer forming dispersion having a solid content concentration of 4 to 10% by weight and adjusting the viscosity within a range of 5 to 22 cp onto a conductive support of 5 to 22 cp.

Since the dispersion liquid for forming a photoconductive layer (hereinafter referred to as dispersion liquid) to which the present invention is applied exhibits titanium-tropic behavior, it is necessary to specify measurement conditions when specifying its viscosity. The viscosity of the dispersion liquid in the present invention is E
Using a type viscometer, 25°C, 2 Or, p
, values measured under strict conditions shall be adopted.

Phthalocyanine is used as the photoconductive compound for the photoconductive layer according to the present invention. Phthalocyanine is designated as
No. 780, No. 45-8102, No. 45-11021, No. 46-42511, No. 46-42512, No. 4
No. 8-163, No. 4917535, No. 50-5059
and JP-A-64-569, JP-A-64-17066, JP-A-61-45474, JP-A-1-144057,
No. 1-153757, No. 1-217362, No. 1-
No. 221459, No. 1-252967, No. 1-285
No. 952, No. 1-312551, No. 2-8256,
The photoconductive phthalocyanine described in Publication No. 2-16570 etc. is represented by the formula (Cs H4N2)a Rn, where R is hydrogen, lydium, sodium, potassium,
Copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, indium, lutetium, titanium, tin, hafnium, lead, vanadium, antimony, chromium, molybdenum, manganese,
These are iron, cobalt, nickel, rhodium, palladium, osmium, and platinum, and n is 0 to 2.

Among these, α, β, γ, π, τ, χ, and ε type metal-free phthalocyanines, or metal phthalocyanines such as copper, magnesium, cobalt, lead, zinc, and titanyl (T i O) are preferred, and He- Preferred are x-type metal-free phthalocyanine, β-type copper phthalocyanine, and titanyl phthalocyanine, which have practical photosensitivity even in the long wavelength region corresponding to light sources such as Ne lasers and semiconductor lasers.

The photoconductive layer for an electrophotographic printing plate according to the present invention comprises at least phthalocyanine and a binder resin. In this electrophotographic photoconductive layer, it is necessary to finally remove the non-image area photoconductive layer, but this step is a process that depends on the relative solubility of the photoconductive layer to the eluent and the resistivity of the toner image to the eluent. It is determined by the relationship that - although it cannot be expressed generally, at least as the binder resin, a polymer compound that is soluble or dispersible in the above-mentioned eluent is preferable.

Specific examples include styrene/maleic anhydride copolymer,
Styrene/maleic acid monoester copolymer, methacrylic acid/methacrylic acid ester copolymer, styrene/methacrylic acid/methacrylic acid ester copolymer, acrylic acid/methacrylic acid ester copolymer, styrene/acrylic acid/methacrylic acid ester Copolymers, vinyl acetate/crotonic acid copolymers, vinyl acetate/crotonic acid/methacrylic acid ester copolymers, etc. with styrene, methacrylic esters, acrylic esters, vinyl acetate, vinyl benzoate, etc., and acrylic acid, methacrylic acid. , copolymers with carboxylic acid-containing monomers such as itaconic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid or monomers containing acid anhydride groups, methacrylic acid amide, vinylpyrrolidone, acryloylmorpholine, and phenolic hydroxyl groups. , sulfonic acid group,
Examples include copolymers containing monomers having sulfonamide groups and sulfonimide groups, phenol resins, partially saponified vinyl acetate resins, xylene resins, and vinyl acetal resins such as polyvinyl butyral.

A monomer-containing copolymer having an acid anhydride group or a carboxylic acid group and a phenol resin have a high charge retention ability when used as a photoreceptor for an electrophotographic printing plate, and therefore can be advantageously used.

The binder resin may be used alone or in combination of two or more types.

When only phthalocyanine and a binder resin are used, if the phthalocyanine content is small, the sensitivity will be low.
It is preferable to use a mixture of 1/20 or more, more preferably 1/6 or more (in terms of weight). However, because
Even if the content of the photoconductive compound is too large relative to the binder resin, not only is it impossible to expect an improvement in sensitivity compared to an increase in the content, but also
Because it becomes impossible to maintain a balance with other electrophotographic characteristics, etc.
The mixing ratio (P/B) of the binder resin and the photoconductive compound is ]/
A range of 6 to 1/2 is desirable. In addition, if the photoconductive layer is too thin, the charge necessary for toner development cannot be charged, and if it is too thick, it not only accelerates the deterioration of the eluate but also induces side etching during elution, resulting in poor images. Since it is not obtained, 0
．． 10-30μm, more preferably 0.50-10μm
m is good. The electrophotographic lithographic printing plate according to the present invention is obtained by coating a photoconductive layer on a conductive support. In producing 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 may contain higher acid value and/or A method is known in which a binder resin having a low molecular weight and easily soluble in alkali is filled, and the upper layer is separated into a layer having a higher phthalocyanine content, and any method may be used.

The dispersion liquid is prepared by dissolving or dispersing each component constituting the photoconductive layer in an appropriate solvent. The phthalocyanine is dispersed using a dispersing machine such as a ball mill, a paint shaker dyno mill, an attritor, etc. to have an average particle size of 0.01 to 571 m, more preferably 0.05 to 0.2 m.

The binder resin and other additives used in the photoconductive layer can be added during or after dispersing the phthalocyanine.

The coating liquid prepared in this way is applied by spin coating, blade coating,
An electrophotographic lithographic printing plate can be obtained by coating and drying on a support by a known method such as knife coating, reverse roll coating, dip coating, rod bar coating, spray coating, or extrusion coating. Solvents for the coating solution include halogenated hydrocarbons such as dichloromethane, dichloroethane, and chloroform; alcohols such as methanol, ethanol, 2-propanol, and 1-butanol; ketones such as acetone, 2-butanone, and cyclohexanone; −
Examples include glycol ethers such as methoxyethanol and 2-methoxyethyl acetate, cyclic ethers such as oxolane, oxane, and dioxane, and esters such as propyl acetate and butyl acetate. Particularly preferable solvents (dispersion media) for the photoconductive layer include those having at least two or more nitrogen or oxygen atoms in the solvent molecule, dissolving 5% by weight or more of water, and having a specific gravity (at 25°C). It is a solvent having a property of 0.95 or more. Examples of such solvents include 2-methoxyethanol, methyl formate, 2-ethoxyethyl acetate, 2-(2-ethoxyethoxy)ethanol, acetamide, morpholine, N-methylformamide, 2-
(2-ethoxyethoxy)ethyl acetate, 2-methoxyethyl acetate, 1,3-butanediol, 2-
(2-methoxyethoxy)ethanol, ethyl lactate,
1-methyl-2-pyrrolidinone, 1,4 dioxane, 1
．． 2-propanediol, 2oxolane methanol, 1
, 3-propanediol, ethyl cyanoacetate, methyl acetoacetate, ethylene glycol diacetate, 2
-pyrrolidinone, 1,2-ethanediol, diethylene glycol, γ-butyrolactone, 2-furanemethanal and the like.

In addition to the photoconductive compound and the binder resin, the photoconductive layer according to the present invention may optionally contain a plasticizer and a surfactant in order to improve the physical properties of the photoconductive layer such as flexibility and coated surface condition. , other additives can be added.

The solvent may be appropriately selected depending on the solubility of the binder resin used and the dispersibility of the phthalocyanine, but two or more types may be mixed and used in consideration of coating properties, dry film forming properties, etc. When two or more types are mixed, it is particularly desirable to design a dispersion liquid mainly using a solvent having the above-mentioned properties.

Although the viscosity of the dispersion significantly affects coating properties, it is important that the viscosity of the dispersion according to the present invention be within the range of 5 to 22 cp. If the viscosity of the dispersion is lower than 5 cp,
During drying, drying unevenness such as color unevenness tends to occur, and it becomes difficult to maintain the desired film thickness after drying and apply uniformly in the width direction. On the other hand, if the viscosity of the dispersion is higher than 22 cp, coating streaks and the like are likely to occur, and the titathotropic properties of the dispersion are more pronounced, making it difficult to control homogeneous coating. A more preferred dispersion viscosity range is 8 to 20 cp.

The above viscosity range is preferably adjusted so that the solid content concentration of the dispersion is in the range of 4 to 10% by weight. If the solid content concentration is too low, the phthalocyanine pigment tends to aggregate, and if it is too high, pigment dispersion tends to take a long time, which is undesirable.

Next, the conductive support used in the electrophotographic lithographic printing plate according to the present invention will be explained.

Examples of the conductive support used in the present invention include conductive supports having an aluminum oxide surface such as metal plates such as aluminum and copper-aluminum. Their thickness is 0.07 to 2.0 mm.

More preferably, it is 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 conductive support according to the present invention may be surface-treated at least on the surface on which the photoconductive layer is provided, if necessary, so that the centerline average roughness (Ra) of the photoconductive layer side surface of the support is 0.3 to 0.3. 0
．． The thickness was set to 8 μm.

The center line average roughness (Ra), which expresses surface roughness, can be determined by various measurement methods, but the surface shape of the photoconductive layer side surface of the conductive support according to the present invention is determined by the scanning length and surface roughness. A stylus-type contact device is used, taking into consideration the level of sensitivity.

The center line average roughness Ra is defined by sampling a measurement length section from the extraction curve in the direction of its center line, setting the center line of the sampled section as the X axis, and the direction of vertical magnification as the Z axis, Z＝
When expressed as f(y), it is given by the following formula and expressed in μm.

Ra=l/l, J f (X) l dx
(t-tm) In other words, Ra represents the standard deviation obtained by dividing the area of the part surrounded by the extraction curve and the center line by the measurement length.

The center line average roughness R,a in the present invention is calculated as follows from the above formula:
It is defined by JIS B 06 (N), and in the present invention, the cutoff value is 0.08 mm and the measurement length is 0.5 m.
The value measured under the conditions of mrn and scanning speed of 0.06 mrn/sec is adopted.

As the surface treatment method, known methods such as graining and anodic oxidation can be used. Prior to graining, degreasing with a surfactant or alkaline aqueous solution is carried out, if desired. Graining treatment methods include mechanical roughening,
There are electrochemical surface roughening methods, chemical surface selective dissolution methods, etc.

As the mechanical surface roughening method, known methods such as ball polishing, brush polishing, blast polishing, and puff polishing 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. Furthermore, a method that combines both methods can also be used, as disclosed in Japanese Patent Laid-Open No. 54-63902.

In the present invention, an electrochemical surface roughening method using an electrolyte mainly containing mineral acid is used, which is a method of improving the water retention property of the support surface and creating deeper, denser, and more uniform grains than a certain level. is preferred.

The depth of the grain can be arbitrarily set within a specific range by controlling the electrolysis conditions, etc., as disclosed in, for example, Japanese Patent Publication No. 55-34240.

The thus roughened aluminum plate is used after being subjected to alkali etching treatment and neutralization treatment, if necessary.

The aluminum plate subjected to the above treatment is anodized. The electrolyte used for anodizing treatment is sulfuric acid, phosphoric acid, oxalic acid, etc., or a mixed acid thereof.
These electrolytes and their concentrations are appropriately determined depending on the type of electrolyte. The anodizing treatment conditions vary greatly depending on the electrolyte used, so they cannot be specified unconditionally, but the amount of anodized film is preferably 0.10 to 10 g/bo, and more preferably 1.0 to 6 g/bo.
A range of 0 g/rri is preferred.

More preferably, the surface shape of the conductive support having a centerline average roughness (Ra) of 0.3 to 0.8 μm obtained in this way has a bearing length (Rlp) defined in ISO4287/1. A surface roughness of 70 to 85% is desirable.

If the bearing length of the support for the electrophotographic printing plate according to the present invention is less than 70%, the anchoring effect of the photoconductive layer on the support will be halved, and if the bearing length exceeds 85%, the elution will be affected. Therefore, there is an increased possibility that the photoconductive layer remains in the recesses on the surface of the support without being removed, and background smear is likely to occur during printing. A more preferable bearing length range is 73 to 82%.

Between the conductive support and the photoconductive layer, if necessary, in order to improve adhesion, electrophotographic properties, etc.
An intermediate layer as described in Japanese Patent No. 5668, Japanese Patent No. 1-186967, etc. may be provided.

An electrophotographic lithographic printing plate can be obtained by providing the above electrophotographic photoconductive layer on the conductive support thus obtained.

(E) Examples The present invention will be explained in more detail by examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

The viscosity of the dispersion liquid was measured using an E-type viscometer manufactured by Tokyo Keiki Co., Ltd. using a cone A at 25° C. and 2 Or, p, m.

Example 1 *Preparation of conductive support A JIS1050 aluminum sheet was heated at 60°C with 10%N
Immersed in aOH aqueous solution, aluminum dissolution amount is 6g1r
I etched it so that it looked like d. 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 treatment 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 (Support No. 1) 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 0.52 μm.

*Preparation and application of photoconductive layer coating solution The following photoconductive layer composition was dispersed in a paint shaker for 1 hour to prepare a photoconductive layer forming coating solution. At this time,
The liquid viscosity was 14 cp. This coating liquid was coated on the surface treated surface of the support using an extrusion coater so that the solid content coating amount was 4.5 g/rd, dried, and then further heated at 90°C.
, and was heated for 5 minutes to prepare an electrophotographic lithographic printing plate.

Photoconductive layer coating solution 1 Composition: Butyl methacrylate/methacrylic acid copolymer (35% by weight of methacrylic acid) 5 parts by weight χ-type metal-free phthalocyanine 1 part by weight 1.4-dioxane
60 parts by weight 2-ethoxyethyl acetate 14 parts by weight 2-propertool
10 parts by weight *Toner development After the obtained printing plate precursor was charged with corona discharge in a dark place so that the surface potential (VO) was approximately +300■,
Scanning image exposure was performed using a semiconductor laser (780 nm, m), and immediately a positively charged toner (manufactured by Mitsubishi Paper Industries, Ltd., LOM-ED) was applied.
When liquid reversal development was performed with I[[) and the toner was thermally fixed, a toner image with a resolution of 50 lines/mm was obtained on the photoconductive layer with good reproducibility. Furthermore, the sharpness of the image was also good.

Wooden Plate Processing Next, plate making processing was carried out using an automatic eluator, an eluent, a washing liquid, and a rinsing liquid as shown below.

1) Automatic elution machine has an elution tank followed by a washing tank and a rinsing tank, and a drive device that transports the electrophotographic printing plate that has undergone toner development, and a storage tank to transfer the processing liquid from each processing tank to the pump sprayer. An automatic machine was used that had a device for cycling through the nozzle storage tank and a device for replenishing each treatment tank.

2) Eluent 1 composition sodium silicate aqueous solution (S i 02 min 30 heavy weight%,
5i02/Na2O molar ratio 2.5) 20 parts by weight Potassium hydroxide 1 part by weight Pure water
79 parts by weight 3) Washing liquid 1 composition (
20 dm3) 0.1 part by weight of Na dioctyl sulfosuccinate 0.01 part by weight of 2-methyl-3-isothiazolone was dispersed and dissolved in pure water to make 100 parts by weight.
After plate making, 15 ml of a 5% by weight glycine aqueous solution was added every time 10 printing plates (A2 size) were processed.

4) Rinse solution 1 composition (20 dm") 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 After adding sodium hydroxide to the solution to adjust the pH of the solution to 4.7, the solution was made up 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 3 μm on one side and the variation was slight. No malfunctions such as pigment residue) were observed.

Next, when this printing plate was used for printing with an offset printing machine (Hamadustar 600 CD), good printed matter was obtained without staining on at least 100,000 printed matter.

Example 2 A support having the surface shape shown in Table 1 was obtained by changing the electrolytic roughening time during the preparation of the conductive support in Example 1.

(The following is a margin. Table 1 Note) Supports Nos. 6 and 7 have non-uniform surfaces and roughness varies greatly depending on the measurement site.

Photoconductive layer coating liquid 1 was applied to each of the above supports under the same conditions as in Example 1 and dried. When all of the obtained electrophotographic printing plates were developed under the same conditions as in Example 1 and subjected to platemaking treatment, the printing plate obtained from the support NO.
Although a toner image of 0 lines/mm was obtained with good reproducibility and the sharpness of the image was also good, printing durability was poor and peeling of the photoconductive layer occurred during printing. On the other hand, supports NO46 and 7
In printing plates obtained from the above (not included in the present invention), the center line average roughness of the surface of the photoconductive layer also increased, resulting in poor toner image resolution, and during elution, the photoconductive layer was eluted into the troughs on the surface of the support. On the other hand, the side etch fluctuated greatly and toner fine line skipping occurred in some areas.

The printing plates obtained from supports Nos. 003.4 and 5 had good toner image quality, elution properties, and printing properties such as scumming and printing durability, and did not exhibit any problems.

Example 3 JIS1050 aluminum sheet at 60°C and 10% N
Immersed in aOH aqueous solution, aluminum dissolution amount is 6g/r
I etched it to make it RF. 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,
Electrolytic surface roughening was performed in a 3.0% hydrochloric acid aqueous solution at 35 A/dm for 250 seconds, and the surface was washed by immersion in a 20% sulfuric acid aqueous solution at 50° C., followed by water washing. Furthermore, a printing plate support (support No. 8) 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 0.55 μm.

A coating liquid for forming a photoconductive layer was prepared by dispersing the following photoconductive layer composition in a paint shaker for 1 hour. At this time,
The liquid viscosity was 12 cp. This coating liquid was applied to the treated surface of the support using an extrusion coater until the solid content was 4. After coating and drying so that it becomes 5g/rrf,
An electrophotographic lithographic printing plate was prepared by heating at 0° C. for 5 minutes.

Photoconductive layer coating liquid 2 Composition: Butyl methacrylate/methacrylic acid copolymer (30% by weight of methacrylic acid) 5 parts by weight Titanyl phthalocyanine 1 part by weight 2-methoxyethyl acetate 70 parts by weight 2-propanol
10 parts by weight 2-furane methanal
6 parts by weight of the obtained printing plate precursor was charged with corona discharge in a dark place so that the surface potential (V, ) was approximately +300V, and then scanned and exposed using a semiconductor laser (780 nm). Immediately positively charged toner (manufactured by Mitsubishi Paper Mills, LOM)
- When liquid reversal development was performed with ED III) and the toner was thermally fixed, the resolution was 50 lines/mm on the photoconductive layer.
toner images were obtained with good reproducibility. Furthermore, the sharpness of the image was also good.

Next, a plate-making process was performed using an eluent, a washing solution, and a rinsing solution as shown below.

Eluent 2 composition potassium silicate aqueous solution (SiO□ min 20 min amount 0 wt%
2. /2O molar ratio 3.5) 30 parts by weight of sodium hydroxide 1 part by weight of pure water
69 parts by weight Washing liquid 2 composition (20
dm3) Dioctylsulfosuccinic acid Na O, 1 part by weight p-
A solution obtained by dispersing and dissolving 0.01 parts by weight of butyl hydroxybenzoate in pure water to make 100 parts by weight was charged into a washing tank.
15 ml of a 5% by weight glycine aqueous solution was added every time 10 printing plates (A2 size) were processed starting from the 100th plate production.

Rinse solution 2 composition (2 (blm”) 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 part by weight Sodium hydroxide was added to this to adjust the pH of the solution to 4.7, and the pH was adjusted to 100% with pure water.
Parts by weight.

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. No malfunctions such as pigment residue) were observed.

Next, when this printing plate was used for printing with an offset printing machine (Hamadustar 600 CD), good printed matter was obtained without staining on at least 100,000 printed matter.

Example 4 The following binder resin was used in a proportion of 5 times the weight of the following phthalocyanine on the support prepared in Example 3, and was dispersed and dissolved in a mixed solvent of 14-dioxane/2-propatol = 10/3. Prepared to have the liquid viscosity shown in Table 2 (coating liquid No.
3 to 7), and an electrophotographic lithographic printing plate was produced under the same conditions as in Example 3.

*Photoconductive layer composition Butyl methacrylate/butyl acrylate/methacrylic acid copolymer (monomer weight ratio 35:30:35) After charging to a potential (vo) of approximately +300 V, scanning image exposure was performed using a semiconductor laser (780 nm), and immediately a positively charged toner (manufactured by Mitsubishi Paper Industries, LOM-ED) was applied.
In step m), liquid reversal development was performed and the toner was thermally fixed.

Table 2 shows the relationship between the liquid viscosity, the surface properties of the photoconductive layer of the printing plate obtained, and the toner image.

(Left below) As shown in Table 2, the liquid viscosity is low (coating liquid N013, outside the invention)
During drying, the phthalocyanine agglomerated easily, resulting in pale color unevenness on the surface of the photoconductive layer and poor image reproducibility. On the other hand, if the liquid viscosity is high (coating liquid N007, outside the scope of the present invention), coating streaks will occur, and if it is made even higher, the liquid will run out, and only printing plates with no commercial value visually can be produced.

On the other hand, printing plates manufactured within the viscosity range of the present invention (coating liquids Nos. 014 to 6) had good photoconductive layer surface properties and toner image reproducibility.

Example 5 The following photoconductive layer compositions (coating liquids 8 to 11) were coated on the surface-treated surface of the printing plate support prepared in Example 3 under the same conditions as in Example 1 to form an electrophotographic printing plate. Created.

Photoconductive layer coating liquid 8 composition (liquid viscosity: 12 cp) vinyl acetate/
Crotonic acid copolymer (3% by weight of crotonic acid) 5 parts by weight χ-type metal-free phthalocyanine 1 part by weight 14-dioxane 70 parts by weight 2-propertool
16 parts by weight Photoconductive layer coating liquid 9 composition (liquid viscosity:
13cp) Styrene/butyl acrylate/acrylic acid copolymer (weight ratio 45:20:35) 5 parts by weight χ-type metal-free phthalocyanine 1 part by weight Xylene 60 parts by weight 14-dioxane 10 parts by weight 2-propertool
15 parts by weight Photoconductive layer coating liquid 10 Composition (liquid viscosity: 11 cp) Styrene/maleic acid monooctyl ester copolymer (weight ratio 50:50) 5 parts by weight χ-type metal-free phthalocyanine 1 part by weight xylene 45 parts by weight Oxolane 25 Parts by weight 2 - Proper tool 15 parts by weight Photoconductive layer coating liquid 11 Composition (liquid viscosity: 11 cp) Benzyl methacrylate/methacrylic acid copolymer (molar ratio 70:30) 5 parts by weight χ-type metal-free phthalocyanine 1 part by weight 2-
Ethoxyethyl acetate 60 parts by weight 1.4-dioxane 15 parts by weight 2-propertool 12 parts When each of the obtained electrophotographic printing plates was developed with toner in the same manner as in Example 1, all the printing plates of Example 1 were It had the same resolution and image quality as the developed product.

Next, a plate-making process was performed using an eluent, a washing solution, and a rinsing solution as shown below.

Eluent 3 composition Monoethanolamine 0.5 parts by weight Triethanolamine 6 parts by weight Benzyl alcohol 1.5 parts by weight EDTA-4HO,
4 parts by weight Potassium hydroxide 2 parts by weight Pure water
89.6 parts by weight Washing liquid 3 composition (20 dm3) 0.15 parts by weight of polyoxyethylene (6) monooleate 0.20 parts by weight of a 5% by weight hot ethanol solution of dehydroacetic acid was dispersed and dissolved in pure water to make 100 parts by weight. Pour the liquid into the washing tank, and after making the 100th plate, print 10 printing plates (A2 size).
4% by weight ammonium bicarbonate aqueous solution 1 for each plate treatment
0ml was added.

Rinse solution 3 composition (20+lm3) Citric acid 0. 2 parts by weight adipic acid 0. 2 parts by weight phosphoric acid (
85% aqueous solution) 0.4 parts by weight Sorbitan monolaurate 0.05 parts by weight After adding sodium hydroxide to this to adjust the liquid pH to 5°O,
It was made up to 100 parts by weight with pure water.

When plates were made using the above processing solution (the elution time was set so that the side etch was eluted to about 3 μm on one side), all of the plates made showed delays in elution in non-image areas (remaining pigment), etc. No elution failure was observed.

Next, when this printing plate was used for printing on an offset printing machine (Hamadustar 600 CD), all printing plates printed had no stains and remained in good condition for at least 100,000 copies. A print was obtained.

(F) Effects of the Invention The method for producing an electrophotographic printing plate of the present invention improves phthalocyanine dispersibility and coatability.

As a result, a high-quality printed image was obtained with good image resolution and no occurrence of scumming or plate skipping.

Procedural amendment (voluntary) August 23, 1990 Attachment Paper 1, Indication of the case 1990 Patent Application No. 160668 2, Title of invention Method for manufacturing electrophotographic printing plates 3, Person making the amendment Related Patent Applicant Address: 4-2 Marunoshiratama-chome, Chiyoda-ku, Tokyo Contact Address: 4-1 Togane-cho-chome, Katsushika-ku, Tokyo 125 Mitsubishi Paper Mills Co., Ltd. Patent Department 4 (600) 2481 4. Subject of amendment “Detailed Description of the Invention” column of the specification

Claims (1)

[Scope of Claims] 1. A dispersion for forming a photoconductive layer containing at least phthalocyanine and a binder resin and having a solid content concentration of 4 to 10% by weight is coated with aluminum oxide on the surface and having a center line average roughness ( When producing an electrophotographic printing plate by coating on a conductive support having Ra) of 0.3 to 0.8 μm, the dispersion is coated with a viscosity of 5 to 22 cp. A method for producing an electrophotographic printing plate. 2. The phthalocyanine is at least one of x-type metal-free, ε-type copper, and titanyl phthalocyanine, and the binder resin (B) and phthalocyanine (P) contained in the photoconductive layer are
) The method for producing an electrophotographic lithographic printing plate according to claim 1, wherein the weight ratio (P/B) of the electrophotographic printing plate is from 1/6 to 1/2.