JPH03218895A - Plate making method for lithographic printing plates - Google Patents

Abstract

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

Description

Detailed Description of the Invention (A) Technical Field The present invention relates to a plate-making method for an electrophotographic printing plate drawn by an electrophotographic method, and more specifically, the invention relates to a plate-making method for an electrophotographic printing plate drawn by an electrophotographic method, and more specifically, it relates to a plate-making method for an electrophotographic printing plate drawn by an electrophotographic method. The present invention relates to a method of manufacturing a lithographic printing plate by carrying out a washing process in which the washing liquid is circulated and reused after contacting.

(B) Prior art and its problems Conventionally, lithographic offset printing plates have used positive-working photosensitizers whose main components are diazo compounds and phenolic resins, and negative-working photosensitizers whose main components are acrylic monomers and prepolymers. PS plates and the like have been put into practical use, but all of these have low sensitivity and are made by contact exposure of a silver salt photographic film original plate on which an image has been recorded in advance. On the other hand, with the development of computer image processing, large-capacity data storage, and data communication technology, in recent years, everything from inputting, correcting, editing, and layout of manuscripts to page setting has become fully computer-controlled, and can be done instantly using high-speed communication networks and satellite communications. Electronic editing systems that can output to end plotters in remote locations have been put into practical use. This electronic editing system is particularly in high demand in the field of newspaper printing, which requires immediacy. Furthermore, even in fields where originals are preserved in the form of original film, and printing plates are reproduced as needed based on this, with the development of ultra-high capacity recording media such as optical discs, the originals are It is conceivable that information will be stored as digital data on media.

However, direct printing plates, in which printing plates are produced directly from the output of a terminal plotter, have hardly been put into practical use, and even in places where electronic editing systems are in operation, output is made on silver halide photographic film, which is then used as a base. In reality, printing plates are created 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 (e.g., He-Ne laser, semiconductor laser, etc.).

Now, an electrophotographic photoreceptor can be 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 Publications No. 47-47610, No. 48-18325,
Photoconductive zinc oxide/resin dispersion offset printing plate materials described in JP 48-40002 and JP 51-15766 are known; After being wetted with a desensitizing treatment liquid (for example, an acidic aqueous solution containing iron hexacyano salt or inosit hexaphosphate) to make it oil-insensitive, it is subjected to printing. However, offset printing plates treated in this way have a printing life of about 10,000 sheets at most.
It is not suitable for further printing, and has disadvantages such as deterioration of image quality if the composition is made to be more desensitized.

On the other hand, Japanese Patent Publication Nos. 37-17162, 38-7758, 41-2426, 46-39405, 50-19509, 52-2437, 54-1
No. 34632, No. 54-145538, No. 55-15
No. 3948, No. 57147656, No. 57-1618
Organic optical semiconductor/resin printing plate materials such as those described in Japanese Patent No. 63 are also known. These electrophotographic photoreceptors are generally mounted on an aluminum plate, and if the aluminum plate and the photosensitive layer (binder) are firmly bonded, they have essentially the same printing durability as Ps plates. .

The general plate-making method for these electrophotographic lithographic printing plates is to form a toner image on an electrophotographic printing original plate using a photoconductive compound by a known electrophotographic image forming method, and then form a non-image area other than the toner image area. By treating the area with a solution containing an alkaline agent or the like, the photosensitive layer in the non-image area is dissolved and removed from the plate (so-called elution), and the plate is made. In particular, elution is different from alkaline development in Ps plates, and utilizes the difference between the alkali solubility of the toner and that of the photosensitive layer, and the toner-adhered photosensitive layer (image area) elutes due to the resistivity of the toner. However, this does not mean that the photosensitive layer itself in the area where toner is attached is essentially insoluble (or poorly soluble) in alkali, so if elution is excessively promoted, the side surface of the photosensitive layer is called side etch. The leakage of the eluate also corrodes the photosensitive layer in the image area, making it impossible to obtain good fine line reproducibility. Therefore, in order to obtain faithful toner image reproducibility, it is important to select the composition of the toner photosensitive layer and the eluent formulation, but it is also necessary to pay attention to the elution treatment method. For example, in a method in which the eluate is directly supplied from a liquid supply nozzle to the printing plate, as is done in the PS plate development process (equivalent to the elution process), the part where the eluate falls directly into contact with the plate The degree of side etching may differ depending on the part that is in contact with the flow.

This side etch may also be accelerated in the water washing process due to multi-sheet printing.

The water washing process in the electrophotographic printing plate making process is similar to that in the PS plate making process, in that the solubilized non-image area and solubilizer (alkaline agent) remaining on the plate can be removed by the washing liquid. Generally, the electrophotographic photosensitive layer is 24 times thicker than the photosensitive layer of the PS plate due to electrophotographic characteristics such as initial charging potential and printing durability, etc., and the photosensitive layer is eluted while suppressing side etching. Therefore, since the plate is made using a solution with a higher alkaline strength than the PS plate developer, if the washing liquid is recycled and reused as described in JP-A-55-25027, there will be a problem in the PS plate washing process. Liquid p was published earlier than
H increases, which causes further deterioration of side etch in the water-washed area. In order to prevent this pH increase, it has been devised to use a disposable washing solution, but this method requires a large amount of washing solution for each plate, and the eluate composition and electrophotographic photosensitive layer may be eluted. This is not a practical method due to problems such as waste liquid treatment of used washing liquid containing harmful components such as binder resin.

Therefore, a method has been devised in which a buffering agent is contained in the washing liquid to be recycled and reused. For example, Japanese Patent Publication No. Sho 64-8819 discloses a method containing an anionic and/or nonionic surfactant and an organic or inorganic acid (salt) with a pH of 1.5 to 12.5.
According to Japanese Patent Application Laid-Open No. 63-169643,
No. 7 discloses treatment with a surfactant and a specific organic or inorganic acid salt of ethanolamine. Furthermore, conventional PS plate developers generally contain an alkali metal silicate as an alkaline agent, and if the washing solution is relatively new and the pH is below 10, the developer containing the components to be eluted from the photosensitive layer will flow into it. Insoluble matter consisting of silicic acid and/or photosensitive layer components is generated, and if this adheres to the non-image area of the printing plate, it causes printing stains.
As described in No. 9, No. 63-172270, the pH of the first water washing bath after alkaline development is adjusted to 10.5 or higher (12.5 for the former and 13 for the latter). is disclosed.

However, the lower limit of the pH at which elution starts in the photosensitive layer for electrophotographic printing plates, that is, at which side etching progresses, is
Although it depends on the components of the photosensitive layer (eluting ability), it should be around 10.5 at least in a system where no buffer coexists, and in a washing solution with a buffer and/or acid coexisting and the pH is less than 7, the solubilization rate should be around 10.5. This may cause re-agglomeration or poor elution (cleaning) of the photosensitive layer components on the plate and in the solution, and the eluate has a higher alkaline strength than the PS plate developer. I was unable to simply use the water washing method.

(C) Object of the Invention The object of the present invention is to make a lithographic printing plate drawn by an electrophotographic method, in which the lithographic printing plate is brought into contact with an eluent using an automatic elution machine, and then washed with water. When manufacturing lithographic printing plates by processing them in a water washing process that recycles and reuses them, we provide a more stable plate-making method by suppressing the deterioration of the properties of the washing liquid caused by eluate etc. that flow into the plate during multi-plate running. and
Another object of the present invention is to provide a method for making a lithographic printing plate that reduces the frequency of liquid exchange.

(D) Means for Achieving the Object The present invention provides an electrophotographic printing plate that is brought into contact with an alkaline eluate using an automatic eluator and then washed with a washing solution that is recycled and reused. At least 7.0~
This is achieved by finally containing an organic compound having an acid dissociation index (pKa) of 10.5 to maintain the pH of the washing solution at 10.5 or less.

The automatic elution machine according to the present invention is preferably one that conveys an electrophotographic printing plate and has an elution section, a water washing section, a rinsing section, a protective gum application section, and a drying section, but other It is also possible to use an automatic developing machine that is conventionally known for developing PS plates.

The washing liquid according to the present invention has at least 7.0 to 10.
5 contains an organic compound having an acid dissociation index (pKa) to maintain its pH at 10.5 or less. This organic compound (hereinafter, unless otherwise specified, acid dissociation index (pKa) of at least 7.0 to 10.5 according to the present invention)
) is simply referred to as an organic compound, and other organic compounds are referred to as organic substances to distinguish them. ), the washing process can be carried out sufficiently even with water that does not contain organic compounds at least at the beginning, so a liquid that does not contain organic compounds is used as the washing liquid at first, and it is added later to "finally" It may be contained in the washing solution, or it may be added to the washing solution prior to plate making.

In the case of the former (post-addition), the addition starts when the pH of the washing solution is 8.
A range of 5 to 10.5, more preferably 9.5 to 10.0 is desirable. In addition, especially if the plate size is constant, unless the area of the non-image area (eluted area) differs greatly, the increase in pH of the washing liquid is approximately proportional to the amount of plates (number of plates), so the present invention Organic compounds related to can be added.

Even in the case of the latter (first addition), it is possible to add more in accordance with the rise in pH of the washing liquid during printing of multiple plates. Further, when adding the organic compound according to the present invention prior to plate making, the organic compound may be added alone, or may be used as a predispersed or dissolved organic compound in water. When preparing an aqueous solution, a small amount of an organic solvent may be added to promote dissolution. In particular, if the organic compound is a water-soluble solid, it may be immersed in a washing tank so that it is gradually dissolved by liquid flow and pH fluctuation during printing. The pH of the washing liquid according to the present invention must always be kept at 10.5 or less, and at least in the case of washing liquid containing organic compounds, the pH is 7.5 to 10.
It is desirable to keep it in the range of 5, more preferably in the range of 8.0 to 10.0.

The organic compound according to the present invention has an acid dissociation index (pKa) of 7.0 to 10.5, and in compounds having multiple dissociation stages, at least the acid dissociation index (pKa)
pKa) should be between 7.0 and 10.5. The definition of acid dissociation constant is usually specified by the value in an infinitely diluted solution at 25°C, but in the present invention, the acid dissociation constant is specified by the value in an infinitely diluted solution at 25°C.
When measured at 2 moldr3 or less, any compound may be used as long as it falls within the range defined in the present invention. 7.0-1
Examples of organic compounds with an acid dissociation index (pKa) of 0.5 include asparagine, aspartic acid, acetylacetone, adenine, 2-aminoethanol, 2-aminoethanethiol, 0-aminophenol, L-alanyl-L-alanine. , L-alanylglycine, β-alanylglycine, alanine, β-alanine, β-alaninamide, arginine, isoleucine, inosine, uracil, ethylenediamine, 8-quinolinol, guanine, glycyl-alanine, glycine, glycinamide , glutamine, glutamic acid, cresol, chlorophenol,
Salicylaldehyde, sarcosine, diethanolamine, diethylenetriamine, cystine, cysteine, citrulline, 3,4-dihydroxyphenylalanine, N,
N'-dimethylethylenediamine, N,N''-dimethylglycine, serine, taurine, tyrosine, triethanolamine, triethylenetetramine, tris(hydroxymethyl)methylamine, tryptophan, trimethylamine, 1-naphthol, 2-naphthol, 1-nitroso -2 naphthol, m-nitrosophenol, norleucine, parine, histidine, m-hydroxybenzoic acid,
p-hydroxybenzoic acid, 4-hydroxyproline, piperazine, hypoxanthine, pyridoxal, pyrogallol, phenylalanine, phenol, p-phenolsulfonic acid, fluorophenol, 1.2-propanediamine, 1.3-propanediamine, 0 -Promophenol, 1,6-hexanediamine, penzylamine, penzoylacetone, methionine, 2-mercaptoethanol, mercaptoacetic acid, morpholine, lysine, riboflavin, resorcinol, leucine and the like. Further examples of organic compounds according to the present invention include, for example, "Chemistry Handbook. Basic Edition ■" edited by the Chemical Society of Japan, revised 3rd edition in 1982, published by Maruzen Co., Ltd., pages n-3 3 9 to II-3 4 2. Among these, the pK defined in the present invention is
Any organic substance having a can be used. In addition, in the present invention, among these, aspartic acid, β-alanine,
Amino acids such as glycine and glutamic acid and their salts are preferred. These organic compounds according to the present invention may be added as a mixture of two or more types, or different organic compounds may be used for pre-addition and post-addition.

In addition, these organic compounds may be used as a mixture (salt) with an appropriate acid or basic compound, or may be mixed with an appropriate acid or basic compound to make an aqueous solution (aqueous dispersion) in order to adjust the pH and promote dissolution. may be used in combination with a basic compound. In particular, when adding the organic compound-containing solution of the present invention later, its pH is adjusted to 6.
．． It is desirable to adjust the amount to 0 to 9.5 and more preferably 7.0 to 8.0.

The amount of the organic compound according to the present invention added to the washing liquid is 0.

0.040 to 10% by weight, more preferably 0.10 to 5.0% by weight.
0% by weight is preferred.

Since the washing liquid according to the present invention is circulated and reused for washing, gases in the air, bacteria, mold, etc. may be mixed into the washing liquid over time, which not only reduces the effect of the present invention but also causes off-odors. do not have. Therefore, it is desirable that the washing liquid according to the present invention contains a preservative and/or a bactericidal agent. Examples of preservatives and fungicides include 0-phenylphenol,
Phenolic compounds such as parachloromethaxylenol,
Glycine compounds such as alkyl bis(aminoethyl)glycine and bis(alkylaminoethyl)glycine, guanidine compounds such as polyhexamethylene biguanidine,
Carboxylic acids, esters, and their salts such as dehydroacetic acid and benzoic acid esters, triazine compounds such as hydroxyethyl-S-triazine, isothiazolone compounds such as penzisothiazolone, isothiazolone, and their derivatives, α-(4-thiazolyl) ) Penzimidazole, alpha
- Imidazole compounds such as (carbomethoxyamino)penzimidazole, 2.3.5.6 Tetrachlor 4-
Examples include pyridine compounds such as methylsulfonylpyridine, amide compounds such as dithiobis(benzmethylamide), and other N,N-dimethyl-N゛-phenyl-N゜-fluorozylene methylthiosulfamide, but in particular, isothiazolone type compounds are preferred.

These preservatives and disinfectants can be used alone or in combination of two or more. When adding it to the washing liquid, it is preferable to dissolve it in water and a suitable organic solvent in advance. Also, these may be added prior to plate making, or
It may be added once or in several parts at a desired time.

The amount added to the washing liquid depends on the type of compound used (sterilizing power)
Although it is necessary to adjust the amount depending on the type and amount of bacteria mixed in the washing liquid, it is usually used in the range of 1 to 30000 ppm, more preferably in the range of 10 to 10,000 ppm.

In addition, known additives that do not cause aggregation with organic compounds can be mixed in the washing liquid according to the present invention. Examples include: ■) titanium oxide described in Japanese Patent Publication No. 62-62341;
Metal oxide fine particles such as silicon oxide, and metal oxide fine particles whose surfaces are coated with inorganic substances such as alumina, organic substances such as low-molecular polyols, chelating agents, surfactants, etc. to improve dispersibility, etc.; 2) Special features Alkali-soluble resins such as phenol formaldehyde resin, cresol formaldehyde resin, xylene resin, and polyhydroxystyrene resin described in Publication No. 61-45554, 3) JP-A-50-51324, JP-A-51-58101, JP-A-61-261095 No. 62-143055,
Nonionic and anionic compounds described in Japanese Patent Publication No. 8819/1983. Surfactant, 4) Organometallic surfactant described in JP-A-59-75255, 5) JP-A-60-225798, JP-A-61-18999
6, inorganic and organic phosphoric acid compounds and phosphonic acid compounds described in JP-A No. 61-261095, etc., 6) Liquid surface tension regulators described in JP-A-63-158552, etc., 7) JP-A-Sho 63-158552, etc. Acids or buffers described in JP-A-62-143055, etc. 8) JP-A-62-275782, JP-A-63-19169
No. 3, JP-A No. 1-125292, JP-A No. 1-177541
Natural and synthetic water-soluble polymers described in JP-A No. 62-73270, 9) antifoaming agents described in JP-A-62-73270, and chelating agents. These additives may be added to the washing liquid in advance, or may be added afterwards together with the liquid containing the organic compound.

The washing section must have a mechanism capable of supplying a washing liquid onto the plate and quickly and completely removing the solubilized photosensitive layer and eluate. The liquid may be directly supplied onto the plate as long as the mechanism can suppress scattering, or the elution promoting member described in JP-A-60-76395 may be applied to the washing mechanism.

Next, other processing liquids and the like related to the present invention will be explained.

The eluent according to the present invention preferably contains an alkaline agent and has a buffering capacity. Examples of alkaline agents include silicates expressed by the general formula S i 02 /M2 0 (M-NaK), alkali metal hydroxides, inorganic alkaline agents such as alkali metal phosphoric acid/carbonate and ammonium salts, ethanolamine, and propane. Examples include organic alkaline agents typified by amines such as diamines, and mixtures thereof, and the silicates mentioned above are particularly advantageous because they exhibit a strong buffering ability. In terms of formulation, it is desirable to add an alkali metal hydroxide to this. The eluate also contains JP-A-55-2.
Ionic compound described in No. 5100, JP-A-55-9
Water-soluble cationic polymers described in JP-A-5946, water-soluble amphoteric polymer electrolytes as described in JP-A-56-142528, neutral salts as described in JP-A-58-75152, JP-A-58-190952 Chelating agents described in JP-A No. 1-177541, liquid viscosity modifiers described in JP-A-1-177541, preservatives and bactericidal agents described in JP-A-63-226657, various surfactants, and known natural and synthetic water-soluble bolimars. Components may be included as necessary.

The solvent in the eluate is not particularly limited as long as it can stably disperse and dissolve the above components, but water, more preferably ion-exchanged water, is advantageously used. Further, in order to further stabilize the above components, a small amount of an organic solvent may be contained.

Especially when using the above silicate in an alkaline agent, S
i02/M20=0.5 to 8.5 (in terms of mole) is preferable. The pH of the eluate is preferably 11.5 to 14.0, more preferably 12.0 to 13.5, and the desired replenisher should be added at appropriate times in case of pH fluctuations during multi-plate printing or over time of the solution. It is desirable to improve the elution activity.

The automatic dissolution machine according to the present invention uses plate preparation, desensitization, and protection agents such as rinsing liquid and protective gum liquid in order to prevent the surface layer of the support in the non-image area from becoming oil-sensitized and to prevent scratches on the surface of the image area. It is better to have a mechanism that can supply the material onto the plate. As for the composition and supply method of the plate surface protective agent, known ones can be used.

The lithographic printing plate according to the present invention contains at least an organic photoconductive compound and a binder resin on a conductive support, and is capable of forming a toner image by a conventional electrophotographic development method.

The electrically conductive supports used in the invention include plastic sheets with electrically conductive surfaces, impermeable and electrically conductive papers, or aluminum, zinc, copper-aluminum,
Examples include conductive supports having a hydrophilic treated surface such as metal plates such as bimetals such as copper-stainless steel and chrome-copper, tri-metals such as chrome-copper-aluminum, chrome-lead-iron, and chrome-copper-stainless steel. Their thickness is 0
．． 1-2mm. More preferably, it is 0.15 to 0.5. 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. Further, it can be used after graining and anodizing using known methods.

Prior to graining, degreasing with a surfactant or alkaline aqueous solution is carried out, if desired. Graining treatment methods include mechanical surface roughening methods, electrochemical surface roughening methods, chemical surface selective dissolution methods, and the like. As the mechanical surface roughening method, known methods such as 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 combining the two can also be used, as disclosed in Japanese Patent Application Laid-Open No. 54-63902.

The aluminum plate whose surface has been roughened in this manner is used after being subjected to alkali etching treatment and neutralization treatment as required.

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 conditions for anodizing treatment vary greatly depending on the electrolyte used, so they cannot be specified, but in general, the electrolyte concentration is 1.0 to 80% by weight, and the liquid temperature is 5.0 to 70°C.
, current density is 5.0~60A/d, voltage is 1.0~I
00V and electrolysis time should be in the range of 10 to 3000 seconds. The amount of anodic oxide film obtained in this way is 0.10~
10 g/% is good, and a range of 1.0 to 6.0 g/rrr is more preferable.

Furthermore, as described in Japanese Patent Publication No. 47-5125, it is also preferable to use an anodic oxidation treatment followed by treatment with an aqueous alkali metal silicate solution. In addition, silicate electrodeposition described in US Pat. No. 3,658,662 is also effective. Treatment with polyvinylsulfonic acid as described in DE 1621478 is also suitable.

Between the conductive support and the photoconductive layer (photosensitive layer), casein,
An alkali-soluble intermediate layer made of polyvinyl alcohol, ethyl cellulose, phenolic resin, styrene/maleic anhydride copolymer, polyacrylic acid, or the like may be provided.

A known electrophotographic photosensitive layer (photoconductive layer) can be provided on the conductive support thus obtained to obtain an electrophotographic photoreceptor.

As the photoconductive material used for the photoconductive layer, known organic or inorganic compounds can be used.

Examples of inorganic photoconductive materials include cadmium sulfide and zinc oxide.

In addition, organic photoconductive materials include a) triazole derivatives described in US Pat. No. 3,112,197, etc., b) oxadiazole derivatives described in US Pat. No. 3,189,447, etc., and C) Japanese Patent Publication No. 1983- d) Imidazole derivatives described in US Pat. No. 3,542,544, US Pat. No. 3,615,402, US Pat.
No. 5-108667, No. 55-156953, No. 56
-36636, polyarylalkane derivatives described in publications, e) U.S. Patent No. 3180729, U.S. Patent No. 4278
Specification No. 746, JP-A-55-88064, JP-A-55-88064
No. 88065, No. 49-105537, No. 55-51
No. 086, No. 56-80051, No. 56-88141
No. 57-45545, No. 54-112637,
Pyrazoline derivatives and pyrazolone derivatives described in No. 55-74546, gazettes, etc., f) U.S. Patent No. 3,615,404, Japanese Patent Publication No. 1973-
No. 10105, No. 46-3712, No. 47-2833
No. 6, JP-A-54-83435, JP-A No. 54-11083
No. 6, U.S. Pat. No. 54-119925, U.S. Patent Nos. 54-119925, U.S. Pat.
No. 8520, No. 4232103, No. 4175961, No. 4012376, West German Patent (DAS) 1110
Specification No. 518, Japanese Patent Publication No. 49-35702, No. 39-
No. 27577, JP-A-55-144250, JP-A No. 56-
Arylamine derivatives described in No. 119132, No. 56-22437, publications, h) U.S. Patent No. 352650
Amino-substituted chalcone derivatives described in Specification No. 1, i) N described in U.S. Patent No. 3,542,546, etc.
N-bicalbasil derivatives, j) Oxazole derivatives described in US Pat. No. 3,257,203, etc., k) Styryl anthracene derivatives, described in JP-A-56-46234, etc., (2) JP-A-54-110837, etc. Fluorenone derivatives described in m) U.S. Pat.
No. 59143 (corresponding to U.S. Pat. No. 4,150,987),
No. 55-52063, No. 55-52064, No. 55
-46760, 55-85495, 57-11
No. 350, No. 57-148749, No. 57-1041
44, hydrazone derivatives described in publications, etc. n) U.S. Pat. No. 4,047,948, U.S. Pat. No. 4,047,949, U.S. Pat.
Benzidine derivatives described in JP-A-58-190953 and JP-A-59-95540, etc.
No. 59-97148, No. 59-195658,
stilbene derivatives described in Japanese Patent Publication No. 62-36674, p) polyvinyl rubberazole and derivatives thereof described in Japanese Patent Publication No. 34-10966, q) stilbene derivatives described in Japanese Patent Publication No. 18674-1974 and Japanese Patent Publication No. 43-19192. Vinyl polymers such as polyvinylpyrene, polyvinyanthracene, poly-2-vinyl-1-(4'dimethylaminophenyl)-5-phenyloxazole, poly-3-vinyl-N-ethylrubazole, r) Japanese Patent Publication Publication No. 1973 - Polymers such as polyacenaphthylene, polyindene, acenaphthylene/styrene copolymer, etc. described in Japanese Patent Publication No. 19193;
Formaldehyde resin, condensation resin such as ethyl carbazole/formaldehyde resin, t) JP-A-5'6-9088
Various triphenylmethane polymers described in U.S. Pat. No. 3,397,086, U.S. Pat.
43, No. 64-2061, No. 64-4389, etc., include metal-free or metal (oxide) phthalocyanines and naphthalocyanines, and derivatives thereof.

The organic photoconductive compounds according to the present invention include a) to U).
The present invention is not limited to the compounds listed above, and conventionally known organic photoconductive compounds can be used. Two or more types of these organic photoconductive compounds can be used in combination, if desired.

Furthermore, various pigments, dyes, etc. can be used in combination for the purpose of improving the sensitivity of the photoconductor or imparting sensitivity to a desired wavelength range.

Examples of these include: 1) U.S. Pat. No. 4,436,800, U.S. Pat.
No. 41, No. 58-192042, No. 58-21926
No. 3, No. 59-78356, No. 60-179746, No. 6 1-14 8 4 5 3, No. 61-238
No. 063, Special Publication No. 60-5941, No. 60-4566
Monoazo, bisazo, and trisazo pigments described in U.S. Pat. ) U.S. Patent No. 33
4) Indigo and thioindigo derivatives described in British Patent No. 2237680, etc.; 5) Quinacridone pigments described in British Patent No. 2237679, etc.; 6) British Patent No. 2237679, etc.; Patent No. 2237678, JP-A-59-
7) Bisbenzimidazole pigments described in JP-A-47-30331, etc.; 8) U.S. Pat. Nos. 4,396,610 and 4,644,082. Squarium salt-based pigments described in specifications, etc., 9) JP-A-1989-1999
Azurenium salt pigments described in Publications No. 9-53850 and No. 61-212542.

In addition, as a sensitization fee, "electronic photography" 129 (1
9 7 3), “Organic Synthetic Chemistry” 24 No. 11
1010 (1966) and the like can be used.

Examples include: 1 1) Applied Optics Supplement
emenl 350 (1969), Japanese Patent Application Publication No. 1973-
12) Cyanine dyes described in US Pat. No. 3,597,196, etc.; 13) JP-A-59-164588, 6o-1630.
47, 60-252517, and the like.

These sensitizing dyes may be used alone or in combination of two or more.

The photosensitive layer according to the present invention contains compounds such as trinitrofluorenone, chloranil, and tetracyanoethylene in order to improve sensitivity and the like.
No. 239, No. 58-129439, No. 60-7196
Compounds described in Publication No. 5 and the like can be used in combination.

In photoreceptors for electrophotographic printing plates, the photoconductive compound itself may have film properties, but if the photoconductive compound alone does not have film properties, a binder resin can be used in combination. . In the electrophotographic photosensitive layer according to the present invention, it is necessary to finally remove the photosensitive layer in the non-image area, but this step depends on the relative solubility of the photosensitive layer to the eluent and the resistivity of the toner image to the eluate. Although it is determined by the relationship and cannot be expressed unconditionally, 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 anhydride monoalkyl ester copolymer, methacrylic acid/methacrylic ester copolymer, styrene/methacrylic acid/methacrylic ester copolymer, acrylic acid/methacrylic ester copolymer, styrene/acrylic acid/methacrylate Acid ester copolymers, vinyl acetate/crotonic acid copolymers, vinyl acetate/crotonic acid/methacrylic ester copolymers, etc. with styrene, methacrylic esters, acrylic esters, vinyl acetate, etc., and acrylic acid, methacrylic acid, itacon acid, crotonic acid,
Copolymers with carboxylic acid-containing monomers such as maleic acid, maleic anhydride, and fumaric acid or acid anhydride group-containing monomers, methacrylic acid amide, vinylpyrrolidone, phenolic hydroxyl group, sulfonic acid group, sulfonamide group, sulfonimide Examples include copolymers containing monomers having 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.

As the monomer-containing copolymer having an acid anhydride group, a copolymer of styrene and maleic anhydride is preferred. Examples of monomer-containing copolymers having carboxylic acid groups include copolymers of styrene and maleic acid half esters, and copolymers of two or more acrylic acids or methacrylic acids and their alkyl esters, aryl esters, or aralkyl esters. Combination is preferred. Also good are vinyl acetate and crotonic acid. Among the phenol resins, particularly preferred are novolak resins obtained by condensing phenol, 0-cresol, m-cresol, or p-cresol with methanal or ethanal under acidic conditions. The binder resin may be used alone or in combination of two or more types.

When using a photoconductive compound and a binder resin, if the content of the photoconductive compound is small, the sensitivity will be low. It is preferable to use a mixture of 15 parts by weight or more. In addition, if the photosensitive layer is thin, the charge necessary for toner development cannot be charged, and if it is thick, it not only accelerates the deterioration of the eluate but also induces side etching during elution, making it impossible to obtain a good image. Therefore, the thickness is preferably 0.1 to 30 μm, more preferably 0.5 to 10 μm.

The electrophotographic lithographic printing plate according to the present invention is obtained by coating a photosensitive layer on a conductive support according to a conventional method. In preparing the photosensitive layer, the components constituting the photoconductive layer may be contained in the same layer, or they may be contained separately in two or more layers, for example, a charge carrier generating substance and a charge carrier transporting substance may be contained in different layers. There are known methods for separating the layer into layers, and it can be produced by any of these methods. The coating solution is prepared by dissolving each component constituting the photoconductive layer in an appropriate solvent, but when using components that are insoluble in solvents such as pigments, dispersion using a ball mill, paint shaker, dyno mill, attritor, etc. It is used after being dispersed by a machine to an average particle size of 0.01 to 5 μm. The binder resin and other additives used in the photoconductive layer can be added during or after dispersing the pigment. The coating solution prepared in this manner is applied onto a support by a known method such as spin coating, blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, or spray coating and is dried to form an electrophotographic printing plate. can be obtained.

Solvents for the coating solution include halogenated hydrocarbons such as dichloromethane, dichloroethane, and chloroform, alcohols such as methanol and ethanol, ketones such as acetone, 2-butanone, and cyclohexanone, ethylene glycol monomethyl ether, - Glycol ethers such as methoxyethyl acetate, oxolane, oxane,
Examples include cyclic ethers such as dioxane, and esters such as 1-propyl acetate and butyl acetate. In addition to the photoconductive compound and the binder resin, the photoconductive layer may contain, if necessary, in order to improve the physical properties of the photoconductive layer such as its flexibility and coating surface condition.
Plasticizers, surfactants and other additives can be added. Examples of the plasticizer include biphenyl, biphenyl chloride, 0-terphenyl, p-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, and triphenyl phosphoric acid.

The electrophotographic lithographic printing plate used in the present invention can be produced by known operations using the above-mentioned electrophotographic photoreceptor. That is, it is charged substantially uniformly in a dark place, and an electrostatic latent image is formed by imagewise exposure. Exposure methods include reflection image exposure using a xenon lamp, tungsten lamp, fluorescent lamp, etc. as a light source, contact exposure through a transparent positive film, and scanning exposure using a laser beam, a light emitting diode, etc. When performing scanning exposure, use He-Ne laser, He-
Cd laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, GaAs/GaAIAs
, scanning exposure using laser light sources such as semiconductor lasers such as InGaAsP, alexandrite lasers, and copper vapor lasers, or scanning exposure using light emitting diodes and liquid crystal shutters (line printer type using light emitting diode arrays, liquid crystal shutter arrays, etc.) (including a light source).

Next, the electrostatic latent image is developed with toner.

As the development method, either dry development (cascade development, magnetic brush development, powder cloud development) or liquid development can be used. In particular, the liquid development method can form fine toner images and is suitable for producing printing plates with good reproducibility. Furthermore, positive/positive development by normal development or negative/positive development by reversal development under application of an appropriate bias voltage is also possible. The formed toner image can be fixed by a known fixing method, such as heat fixing, pressure fixing, solvent fixing, or the like. A printing plate can be prepared by using the toner image thus formed as a resist and removing the photosensitive layer in the non-image area with an eluent.

The toner according to the present invention needs to contain a resin component that has resistivity to the eluent.

Examples of resin components include acrylic resins made of methacrylic acid, methacrylic esters, etc., vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, etc.
Vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, etc., polyethylene, polypropylene and their chlorides,
Polyester resins such as polyethylene terephthalate and polyethylene isophthalate, polyamide resins such as polycapramide and polyhexamethylene adipamide, phenolic resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, gelatin, cellulose ester derivatives such as carboxymethyl cellulose, etc. Examples include wax and wax.

Further, the toner can also contain a dye or a charge control agent within a range that does not adversely affect development, fixing, etc.

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

Example I JIS1050 aluminum sheet at 60°C and 10% N
When immersed in aOH aqueous solution, the amount of aluminum dissolved was 6 g/
It was etched to become rrf. 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. Thereafter, electrolytic surface roughening was performed for 20 seconds in a 0.7% nitric acid aqueous solution, and the surface was washed by immersion in a 20% sulfuric acid aqueous solution at 50° C., followed by water washing. Furthermore, a support for a printing plate was prepared by performing anodization treatment in a 20% aqueous sulfuric acid solution, washing with water, and drying.

On the surface-treated surface of this support, the following photosensitive composition was dispersed in a paint shaker for 1 hour, coated with a bar coater, and dried at 90° C. for 5 minutes to prepare an electrophotographic lithographic printing plate. At this time, the coating amount of the photosensitive layer was 4.5 g/rd.

Photosensitive layer coating composition Butyl methacrylate/methacrylic acid copolymer 18 parts by weight (molecular weight 50,000, acid value 200) Metal-free cap cyanine 4 parts by weight 1-Butyl acetate 60 parts by weight 2-propanol
18 parts by weight of the obtained printing plate precursor was charged with a corona discharge in a dark place so that the surface potential (VO) was about +300μ, and then scanned and exposed using a semiconductor laser (780 nm). Immediately positively charged toner (Mitsubishi Paper Mills■
Manufactured by LOM-EDI [[], liquid reversal development is carried out,
The toner was thermally fixed to obtain a toner image on the photosensitive layer.

Next, a sodium silicate aqueous solution (S i 02 min 30%,
S i 02 /Na20 molar ratio 2.5) 20 parts by weight and 1.0 parts by weight of potassium hydroxide were diluted with pure water to give 100 parts by weight.
The pH of the solution was adjusted to 8.0±0.0 by adding the eluate in parts by weight, the compounds listed in Table 1, and, if necessary, hydrochloric acid or aqueous sodium hydroxide solution. 1 washing liquid (20dm3
) until the pH of the washing solution reaches 10.5.
000 sheets continuous plate making (A2 size) was performed.

(Margin below) Table 1 Note) pKa 1 and 2 represent the number of dissociation stages.

In addition, the evaluation of the washing liquid was performed as follows.

<Evaluation of ability to suppress elution progress> Exposure of non-image areas when the uneluted printing plate after toner development was immersed in the recirculated and reused washing solution after the plate-making process for 10 seconds and 30 seconds, and then immediately washed with pure water. Evaluate the degree of layer elution.

1: Not eluted at all; 2: Not eluted at all at 10 seconds, but the surface of the photosensitive layer is slightly eluted at 30 seconds; 3: The surface of the photosensitive layer is eluted even at 10 seconds (elution rate less than 5%); 4 : Elution rate of photosensitive layer in non-image area after 10 seconds 5 to 50%, 5: Elution rate>50%, <Evaluation of washing liquid property> Washing liquid during and after 1000 plate printing was filtered through a #325 mesh wire mesh. Then, when this filtrate was allowed to stand still for an additional 5 days, the liquid change and filtration residue (aggregates) were evaluated.

A: Aggregation and gelation of the liquid do not occur until the end of printing. B: No aggregation and gelation occur during printing, but gelation occurs at the latest on the 5th day. C: Aggregation occurs during printing. and/or occurrence of gelation, washing solution conditions (compound concentration), and the results obtained are listed in Table 2.

(Margins below) 2. With the washing solution containing only surface water (Test No. 8), the pH of the solution rose relatively early in plate making, and as plate making continued, side etch worsened, resulting in images (thin lines). Reproducibility could not be achieved. In addition, the acid dissociation index (p
Washing solution to which a compound without Ka) was added (Test No.
In the case of 6 and 7), although the pH rise is much slower than when only water is used, side etch progresses in the water washing area as the pH rises, and at the same time, the stability of the washing liquid itself is lost, and sooner or later the water washing becomes impossible. The liquid turned into a gel. On the other hand, as can be seen from Table 2, the washing liquid (Test Nos. 1 to 5) to which an organic compound having an acid dissociation index (pKa) of at least 7.0 to 10.5 was added according to the present invention By adding a relatively small amount, the increase in pt-i was suppressed, and stable plate making could be performed without causing aggregation or gelation even over time. In particular, the systems to which amino acids were added (Test Nos. 1, 2, and 4) exhibited excellent elution suppression ability.

Example 2 Using water as the washing liquid under the same plate-making conditions as in Example 1, 1
When 00 plates were printed (washing liquid pH 10.1), an aqueous arginine solution was added to the washing liquid at a concentration of 0.80% by weight, and a total of 900 plates and 1000 plates were made. As a result, Example 1 Test No. As with 2, the plate making was completed without any problems. Similarly, when glutamic acid and p-hydroxybenzoic acid (pH adjusted with sodium hydroxide) were added,
Good results were obtained.

Example 3 Using water as the washing liquid under the same plate-making conditions as Example 1, 1
At the time of printing 00 plates, an aspartic acid aqueous solution whose pH was adjusted with potassium hydroxide was added at 0.20% by weight in terms of solid content, and thereafter the same amount of aspartic acid aqueous solution was added for every 200 plates, making a total of 1100 plates. I was able to perform plate making stably until the end.

Example 4 Example 1 Test No. After adding 4 dm3 of 5 wt % serine aqueous solution to the washing solution for making 1000 plates in step 2,
When the 000 plate was made, the elution suppression ability was slightly deteriorated, but the plate making was completed without any major problems. Similarly, Example 1 Test No. After adding 20% by weight aqueous glycine solution (adjusted to pH = 7, 5 with lithium hydroxide) to the washing solution after making 1000 plates in step 4, the plate was made for 1000 plates.
I was able to make a plate while maintaining stable liquid properties until the end.

Example 5 Example 1 Test No. Plate making was carried out under the same conditions as in Example 1, except that 20 ppm of the preservative 2-methylisothiazolin-3-one was further added to the washing solution of Example 1.

As a result, the plate could be made without any adverse effect on the properties of the washing liquid or the plate-made product. In addition, 1,2-benzolthiazolin-3-one and hydroxyethyl-S-triazine (25 ppm each) were used instead of 2-methylisothiazolin-3-one. The plate was made in the same manner as above, and similar results were obtained.

(F) Effects of the Invention According to the method of the present invention, it was possible to lengthen the period for replacing the washing liquid by not generating aggregates in the washing tank and suppressing deterioration such as side etching.

Claims (1)

[Claims] 1. An electrophotographic lithographic printing plate on which a toner image has been formed using an electrophotographic method is brought into contact with an alkaline eluent using an automatic eluator, and then washed with a washing liquid that is circulated and reused. In the method for making a lithographic printing plate, the washing solution finally contains an organic compound having an acid dissociation index (pKa) of at least 7.0 to 10.5 to maintain the pH at 10.5 or less. A method for making a lithographic printing plate, characterized by: 2. The method for making a lithographic printing plate according to claim 1, wherein an aqueous solution containing the organic compound and having a pH adjusted to 9.5 or less is added to the washing liquid in accordance with the amount of the lithographic printing plate processed. . 3. The method for making a lithographic printing plate according to claim 1 or 2, wherein the organic compound is an amino acid or a salt thereof. 4. The method for making a lithographic printing plate according to claim 3, wherein the washing liquid further contains at least one of a preservative and a bactericide.