JP2918267B2 - Plate making method of lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field The present invention relates to a method for making an electrophotographic lithographic printing plate drawn by an electrophotographic method, and more particularly, to a method for preparing a lithographic printing plate with an eluent using an automatic dissolution machine. The present invention relates to a method for producing a lithographic printing plate by contacting and then treating in a washing step in which a washing liquid is circulated and reused.

(B) Conventional technology and its problems Conventionally, as a lithographic offset printing plate, a positive photosensitive agent mainly containing a diazo compound and a phenol resin, or a negative photosensitive agent mainly containing an acrylic monomer or a prepolymer is used. PS plates and the like have been put to practical use, but they are all low-sensitivity, and plate making is performed by contact-exposing a silver halide photographic film master on which images have been recorded in advance. On the other hand, with the development of computer image processing, large-volume data storage, and data communication technology, in recent years, document input / correction / edit / layout has been consistently controlled by computer, and pages have been integrated. An electronic editing system that can output to a remote terminal plotter has been put to practical use. In particular, the demand for this electronic editing system is high in the newspaper printing field, which requires immediacy. Also, in fields where the originals are stored in the form of original films and the printing plates are duplicated as necessary based on these, the originals have been developed with the development of ultra-high-capacity recording media such as optical disks. It is conceivable that the data will be stored as digital data on a recording medium.

However, direct printing plates that produce printing plates directly from the output of the terminal plotter have hardly been put to practical use, and even where an electronic editing system is operating, the output is made on silver halide photographic film. In reality, a printing plate is produced indirectly by 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).

Now, an electrophotographic photosensitive member is considered as a photosensitive material having high photosensitivity capable of providing a direct printing plate. Conventionally, as a printing plate material (original plate for printing) using electrophotography, for example, JP-B-47-47610, JP-B-48-18325, JP-B-48-40002,
JP-A-51-15766 discloses a preconductive zinc oxide / resin dispersion type offset printing plate material described in JP-A-51-15766 and the like, in order to make the non-image area insensitive to oil after forming a toner image by electrophotography. After being wetted with a desensitizing solution (for example, an acidic aqueous solution containing hexacyanoiron salt or inosit hexaphosphate), and then subjected to printing. However, the offset printing plate treated in this way has a maximum printing life of about 10,000 sheets, and is not suitable for printing more than that, and if the composition is made insensitive to desensitization, the image quality deteriorates. Has the disadvantage of

On the other hand, Japanese Patent Publication No. 37-17162, 38-7758, 41-2426
No., 46-39405, JP-A-50-19509, 52-2437,
No. 54-134632, No. 54-145538, No. 55-153948, No. 57-
Also known are organic optical semiconductor / resin printing plate materials as described in 147656, 57-161863 and the like. These electrophotographic photoreceptors are generally provided on an aluminum plate, and if the aluminum plate and the photosensitive layer (binder) are firmly adhered, they have essentially the same printing durability as the PS plate .

A general plate-making method in these electrophotographic lithographic printing plates is to form a toner image of an electrophotographic printing original plate using a photoconductive compound by a known electrophotographic image forming method,
By processing the non-image portion other than the toner image portion with a solution containing an alkali agent or the like, the non-image portion photosensitive layer is dissolved and removed (so-called elution) from the plate, thereby making a plate. In particular, the elution is based on the difference between the alkali solubility of the toner and that of the photosensitive layer, unlike the alkali development in the PS plate. The photosensitive layer (image area) where the toner adheres is eluted due to the resist properties of the toner. However, since the photosensitive layer itself at the toner-attached portion does not essentially become alkali-insoluble (or hardly soluble), if the dissolution is excessively promoted, the side surface of the photosensitive layer called a side etch is obtained. The photosensitive layer of the image area is also eroded by the infiltration of the eluate from the ink, and good reproducibility of fine lines cannot be obtained. Therefore, in order to obtain faithful toner image reproducibility, toner,
It is important to select the composition of the photosensitive layer and the formulation of the eluate, but it is also necessary to pay attention to the elution method. For example, as in the PS plate development process (equivalent to the elution process), in the method in which the eluate is supplied directly to the printing plate from the liquid supply nozzle, the part where the eluate directly contacts the plate and that In some cases, the degree of side etching may be different from that of a portion that has flowed and contacted.

This side etch may also be accelerated in the washing process by multi-pass printing.

The water washing process in the electrophotographic lithographic printing plate making process can remove the solubilized non-image part and the solubilizing agent (alkaline agent) remaining on the plate by a washing liquid, as in the PS plate making process. In general, the electrophotographic photosensitive layer is 2-4 times thicker than the PS plate photosensitive layer due to the electrophotographic properties such as initial charging potential and printing durability, and the photosensitive layer is eluted while suppressing side etching. To make a plate using a solution having a higher alkali strength than the PS plate developer,
If the washing liquid is circulated and reused as described in -25027,
The liquid pH rises earlier in the PS plate washing step than in the PS plate washing step, which causes further deterioration of the side etch in the washing section. In order to prevent this pH rise, it has been devised to use a washing solution as a disposable method.However, a large amount of washing solution is required for each plate, and the washing solution is eluted from the eluent composition and the electrophotographic photosensitive layer. It is not a practical method due to problems such as waste liquid treatment in a used washing solution containing harmful components such as a binder resin.

Therefore, a method has been devised in which a buffer is contained in the washing liquid to be recycled and reused. For example, Japanese Patent Publication No. 64-8819 discloses a treatment with an aqueous solution containing an anionic and / or nonionic surfactant and an organic or inorganic acid (salt) at a pH of 1.5 to 12.5. JP-1696437 discloses treatment with a surfactant and a specific organic or inorganic acid salt of ethanolamine. Further, the conventional PS plate developer generally contains an alkali metal silicate as an alkali agent, and the washing solution is relatively new, and when the pH is 10 or less, the developer containing components to be eluted into the photosensitive layer flows into the solution. An insoluble material consisting of silicic acid and / or a photosensitive layer component is formed, and if this adheres to the non-image portion of the printing plate, it causes printing smear. For example, as described in JP-A-63-172269 and JP-A-63-172270. ,
It is disclosed that processing is performed with a liquid in which the pH of the first washing bath after alkali development is adjusted to 10.5 or more (the upper limit of the former is 12.5, and the upper limit of the latter is 13).

However, the elution is started in the electrophotographic printing plate photosensitive layer, that is, the lower limit of the pH at which the side etch proceeds,
Although it depends on the components of the photosensitive layer (elution ability), at least around 10.5 in a system in which no buffer is present, the buffer and / or
Alternatively, a water washing solution having a pH of less than 7 in the presence of an acid causes re-aggregation or elution (washing) of the solubilized photosensitive layer components on the plate and in the solution, and the eluate is PS plate development. Because of the higher alkali strength as compared with the liquid, it was not possible to simply use the water washing method in PS plate making.

(C) Object of the Invention An object of the present invention is to provide an electrophotographic lithographic printing plate made by an electrophotographic method, wherein the lithographic printing plate is brought into contact with an eluate using an automatic dissolution machine, and then washed with water. When manufacturing a lithographic printing plate by processing in a washing step of circulating reuse, the deterioration of the washing liquid characteristics caused by the eluent and the like flowing into the mail order of many sheets is suppressed, and a more stable plate making method is provided. Another object of the present invention is to provide a method of making a lithographic printing plate that reduces the frequency of liquid exchange.

(D) Means for Achieving the Object The present invention relates to a method in which an electrophotographic lithographic printing plate is brought into contact with an alkaline eluent using an automatic dissolution machine and then washed with a washing solution to be recycled. At least 7.0-1
This is achieved by finally including an amino acid having an acid dissociation index (pKa) of 0.5 or a salt thereof, and maintaining the pH of the washing solution at 10.5 or less.

As the automatic dissolution machine according to the present invention, a system for transporting an electrophotographic lithographic printing plate, which has a dissolution unit, a washing unit, a rinsing unit, a protective gum coating unit and a drying unit, is preferably used. A known automatic developing machine or the like can be used in the conventional PS plate development processing.

The washing solution according to the present invention finally contains an amino acid having an acid dissociation index (pKa) of at least 7.0 to 10.5 or a salt thereof, and keeps its pH at 10.5 or less. This amino acid or a salt thereof (hereinafter, unless otherwise specified, the acid dissociation index (pKa) of at least 7.0 to 10.5 according to the present invention)
Are simply referred to as amino acids. ) Can be sufficiently washed at first even with water not containing at least amino acids, so that a liquid containing no amino acids is used as a washing liquid at first, and is added later and finally added. It may be contained in the washing liquid, or may be added to the washing liquid prior to plate making. 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 start of 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). Amino acids related to the above can be added. In the case of the latter (first addition), it can be further added to the multi-sheet printing in accordance with an increase in the pH of the washing solution. When the amino acids according to the present invention are added prior to plate-making, the amino acids may be added alone or may be dispersed or dissolved in water in advance. When preparing an aqueous solution, dissolution may be promoted with a small amount of an organic solvent. In particular, if the amino acids are water-soluble solids, the amino acids 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 according to the present invention must always be kept at 10.5 or less, but at least in the amino acid-containing washing solution, it is in the range of 7.5 to 10.5, more preferably 8.0 to 1.
It is desirable to keep it in the range of 0.0.

The amino acids according to the present invention have an acid dissociation index (pKa) in the range of 7.0 to 10.5. When the compound has a plurality of dissociation stages depending on the compound, at least the acid dissociation index (pKa) is used.
One of them should be between 7.0 and 10.5. The definition of the acid dissociation index is usually specified by the value in an infinitely diluted solution at 25 ° C.
In the present invention, when measured at a solution concentration of 0.2 moldm- ³ or less, any compound within the range specified in the present invention may be used. Examples of amino acids having an acid dissociation index (pKa) of 7.0 to 10.5 include asparagine, aspartic acid, L
-Alanyl-L-alanine, L-alanylglycine, β
-Alanylglycine, alanine, β-alanine, arginine, isoleucine, glycyl-L-alanine, glycine, glutamine, glutamic acid, cystine, cysteine, 3,4-dihydroxyphenylalanine, N, N′-dimethylglycine, serine, tyrosine, Examples include tryptophan, norleucine, valine, histidine, 4-hydroxyproline, phenylalanine, methionine, lysine, leucine and the like. Further examples of the amino acids according to the present invention are described in, for example, "Chemical Handbook: Basic Edition II" edited by The Chemical Society of Japan, 3rd revised edition, 1984, published by Maruzen Co., Ltd., pp. II-339 to II-342. And among these, the pK defined in the present invention.
All amino acids having a can be used. In the present invention, among these, amino acids such as aspartic acid, β-alanine, glycine, and glutamic acid, and salts thereof are particularly preferable. These amino acids according to the present invention are 2
More than one species may be mixed and added, or different amino acids may be used for the first addition and the second addition. These amino acids may be used in the form of a mixture (salt) with a suitable acid or basic compound, or may be mixed with an appropriate acid or basic compound in an aqueous solution (aqueous dispersion) for pH adjustment and dissolution promotion. May be used in combination with a basic compound. Particularly when the amino acid-containing solution of the present invention is added later, its pH is 6.0 to 9.5, more preferably
It is desirable to adjust and add to 7.0 to 8.0.

The amount of the amino acids according to the present invention added to the washing solution is 0.
It is preferably from 0.4 to 10% by weight, more preferably from 0.10 to 5.0% by weight.

Since the washing liquid according to the present invention is used for washing by circulating and reused, gas in the air and bacteria and molds are mixed into the washing liquid over time, which not only reduces the effect of the present invention but also emits an unpleasant odor, which is preferable. Absent. Therefore, it is desirable that the washing liquid according to the present invention contains a preservative and / or a bactericide. Examples of preservatives and bactericides include phenolic compounds such as o-phenylphenol and parachloromethaxylenol; glycine compounds such as alkylbis (aminoethyl) glycine and bis (alkylaminoethyl) glycine;
Guanidine compounds such as polyhexamethylene biguanidine, dehydroacetic acid, carboxylic acids such as benzoate,
Esters and salts thereof, triazine compounds such as hydroxyethyl-S-triazine, benzisothiazolone,
Inch azolone compounds such as inch azolone and derivatives thereof, imidazole compounds such as α- (4-thiazolyl) benzimidazole and α- (carbomethoxyamino) benzimidazole, 2,3,5,6-tetrachloro-
Pyridine compounds such as 4-methylsulfonylpyridine,
Examples thereof include amide compounds such as dithiobis (benzmethylamide) and N, N-dimethyl-N'-phenyl-N'-fluorodichloromethylthio-sulfamide. Of these, isothiazolone compounds are particularly preferable.

One of these preservatives / bactericides can be used, or two or more can be used in combination. When added to the water washing solution, it is preferable to dissolve it in water and a suitable organic solvent in advance.
These may be added prior to the plate making or may be added once or at several times at desired times. The amount to be added to the washing solution needs to be adjusted depending on the type of the compound to be used (bactericidal activity) and the type of bacteria mixed in the washing solution and the amount thereof, but is usually in the range of 1 to 30,000 ppm, more preferably 10 to 10,000 ppm. It is good to use in the range.

The washing solution according to the present invention may further contain known additives that do not cause aggregation with amino acids.
Examples thereof include: 1) Metal oxide fine particles such as titanium oxide and silicon oxide described in Japanese Patent Publication No. 62-62341, and the surface thereof is formed of an inorganic substance such as alumina, a low molecular polyol, a chelating agent, a surfactant, or the like. Metal oxide fine particles coated with an organic substance to improve dispersibility, etc. 2) Alkali-soluble resins such as phenol formaldehyde resin, cresol formaldehyde resin, xylene resin, polyhydroxystyrene resin described in JP-B-61-45554, 3) JP-A-50-51324, JP-A-51-58101, JP-A-61-261095
Nonionic and anionic surfactants described in JP-A Nos. 62-143055 and JP-B-64-8819; 4) Organometallic surfactants described in JP-A-59-75255; No. 60-225798, No. 61-189996, No. 61-26109
No. 5, JP-A-63-141585, etc. 6) Inorganic and organophosphoric acid compounds and phosphonic acid compounds described in JP-A-5-158552, 6) Liquid surface tension regulator described in JP-A-63-158552, etc., 7) JP-A-62-143055, etc. 8) JP-A-62-275782 and JP-A-63-191693;
Natural and synthetic water-soluble polymers described in JP-A-125292 and JP-A-177541, 9) Defoamers described in JP-A-62-73270, and other chelating agents. These additives may be added to the washing solution in advance, or may be added later together with the solution containing amino acids.

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

Next, other processing liquids and the like according to the present invention will be described.

The eluate according to the present invention preferably contains an alkaline agent and has a buffering capacity. As the alkaline agent,
A silicate represented by the general formula SiO ₂ / M ₂ O (M = Na, K);
Inorganic alkali agents such as alkali metal hydroxides, alkali metal and ammonium salts of phosphoric acid and carbonic acid, organic alkali agents typified by amines such as ethanolamine and propanediamine, and mixtures thereof. Silicates are advantageously used because they exhibit a strong buffering capacity. In terms of formulation, it is desirable to add an alkali metal hydroxide to this. The eluate further contains an ionic compound described in JP-A-55-25100, a water-soluble cationic polymer described in JP-A-55-95946, and a water-soluble amphoteric polymer described in JP-A-56-142528 Electrolyte, neutral salt described in JP-A-58-75152, chelating agent described in JP-A-58-190952, liquid viscosity modifier described in JP-A-1-177541, JP-A-63-2
Known components such as preservatives and bactericides described in JP-A-26657, various surfactants, and natural and synthetic water-soluble 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, but water, more preferably, ion-exchanged water is advantageously used. Also,
To stabilize the above components, a small amount of an organic solvent may be contained.

In particular, when using the above silicate in an alkali agent, Si
O ₂ / M ₂ O = 0.5 to 8.5 (mole conversion) is preferred. Eluate p
H is preferably 11.5 to 14.0, more preferably 12.0 to 13.5,
In the case of pH fluctuation during multi-plate printing or solution aging, it is desirable to add a desired replenisher as needed to improve the elution activity.

In the automatic dissolution machine according to the present invention, a rinsing solution, a plate preparation such as a protective gum solution, a desensitizing / protecting agent such as a protective gum solution are used to prevent sensitization of the non-image portion support surface layer and prevent scratches on the image portion surface. It is preferable to have a mechanism capable of supplying on a plate. Known compositions can be used for the composition and supply method of the plate surface protective agent.

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 can form a toner image by a usual electrophotographic development method.

As the conductive support used in the present invention, a plastic sheet having a conductive surface, paper impermeable and conductive, or bimetal such as aluminum, zinc, copper-aluminum, copper-stainless, chromium-copper, Chromium-copper-aluminum, chromium-lead-iron, chromium-copper-
Examples include a conductive support having a hydrophilic surface such as a metal plate such as a trimetal such as stainless steel. Their thickness is preferably 0.1 to 2 mm, more preferably 0.15 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. It can be used after graining and anodizing by a known method. Prior to the graining treatment, if necessary, a degreasing treatment with a surfactant or an aqueous alkali solution is performed. The graining method includes
There are a mechanical surface roughening method, an electrochemical surface roughening method, a chemical surface selective dissolution method, and the like. The mechanical surface roughening method includes ball polishing,
Known methods such as 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 aluminum plate thus roughened is used after being subjected to an alkali etching treatment and a neutralization treatment as necessary.

The aluminum plate that has been subjected to the above-described processing is anodized. 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 electrolyte and the concentration thereof are appropriately determined depending on the type of the electrolyte. Anodizing conditions vary greatly depending on the electrolyte used and cannot be specified unconditionally, but generally the electrolyte concentration is 1.0 to 80% by weight, the liquid temperature is 5.0 to 70 ° C, and the current density is 5.0 to 60 A / dm. ² , Voltage is 1.0 ~ 100V, electrolysis time is 10
It only has to be in the range of ~ 3000 seconds. Anodized film weight obtained in this way has good 0.10~10g / m ^2, more 1.0～6.0G /
A range of m ² is preferred.

Further, as described in JP-B-47-5125, those treated with an aqueous alkali metal silicate solution after anodic oxidation treatment are also suitable. The silicate electrodeposition described in US Pat. No. 3,866,662 is also effective. West German Patent No. 1621478
The treatment with polyvinyl sulfonic acid described in Japanese Patent Application Laid-Open Publication No. H11-279, 1993 is also appropriate.

Casein, polyvinyl alcohol, ethylcellulose, phenolic resin, styrene / maleic anhydride copolymer, if necessary, between the conductive support and the photoconductive layer (photosensitive layer) to improve adhesion and electrophotographic properties. An alkali-soluble intermediate layer made of coalesced or polyacrylic acid may be provided.

A known electrophotographic photosensitive layer (photoconductive layer) is provided on the thus obtained conductive support to obtain an electrophotographic photosensitive member.

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

Examples of the inorganic photoconductive material include cadmium sulfide and zinc oxide.

Examples of the organic photoconductive material include: a) a triazole derivative described in US Pat. No. 3,112,197, etc., b) an oxadiazole derivative described in US Pat. No. 3,189,447, etc., c) Japanese Patent Publication No. Imidazole derivatives described in JP-A-16096, etc., d) U.S. Pat. Nos. 3,542,544, 3,615,402, 3,898,089
No., JP-B-45-555, JP-B-51-10983, JP-A-51-9
No. 3224, No. 55-108667, No. 55-156953, No. 56-36636, polyarylalkane derivatives described in e.g., e) U.S. Pat. Nos. 3,180,729 and 4,278,746, JP-A-55-88064 No. 55-88065, No. 49-105537, No. 55-51
No. 086, No. 56-80051, No. 56-88141, No. 57-45545,
Pyrazoline derivatives and pyrazolone derivatives described in JP-A-54-112637 and JP-A-55-74546, etc. f) US Pat. No. 3,615,404, JP-B-51-10105
No. 46-3712, No. 47-28336, JP-A-54-83435,
Phenylenediamine derivatives described in JP-A-54-110836, JP-A-54-119925, etc. g) US Pat. Nos. 3,567,450, 3,180,703, 3,240,597
No. 3658520, No. 42322103, No. 4159661, No. 40123
No. 76, West German Patent (DAS) 1110518, Japanese Patent Publication No. 49-3
No. 5702, No. 39-27577, JP-A-55-144250, No. 56-1191
Nos. 32, 56-22437, etc., h) Amino-substituted chalcone derivatives described in US Pat. No. 3,352,501, i) N, N- described in US Pat. No. 3,542,546, etc. A bicarbazyl derivative, j) an oxazole derivative described in US Pat. No. 3,257,203, etc., k) a styryl anthracene derivative described in JP-A-56-46234, etc., 1) a JP-A-54-110837, etc. M) U.S. Patent No. 3717462, JP-A-54-59143 (corresponding to U.S. Patent No. 4150987), 55-52063, 55-52063
52064, 55-46760, 55-85495, 57-11350
Hydrazone derivatives described in JP-A Nos. 57-148749 and 57-104144, and n) U.S. Pat. Nos. 4,047,948, 4,047,949 and 4,265,990
No. 4,273,846, No. 42,998, and No. 4,306,008, etc .; o) JP-A-58-190953, JP-A-59-95540, JP-A-59-97148
Stilbene derivatives described in JP-B Nos. 59-195658 and 62-36674, p) Polyvinylcarbazole and derivatives thereof described in JP-B-34-10966, q) JP-B 43-18674, 43 Patent No. -19192 discloses polyvinyl polyvinylene, polyvinyl anthracene, poly-2-
Vinyl-4- (4'-dimethylaminophenyl) -5
Vinyl polymers such as phenyloxazole and poly-3-vinyl-N-ethylcarbazole; r) polymers such as polyacenaphthylene, polyindene and acenaphthylene / styrene copolymer described in JP-B-43-19193; Condensed resins such as pyrene / formaldehyde resin and ethylcarbazole / formaldehyde resin described in JP-B-56-13940, etc. t) Various triphenyls described in JP-A-56-90883 and JP-A-56-161550 Methane polymers, u) Metal-free or metal (oxide) phthalocyanines and naphthalocyanines described in U.S. Pat. Nos. 3,397,866 and 4,668,802, JP-A-64-2061, JP-A-64-4389, and the like; And derivatives thereof.

The organic photoconductive compound according to the present invention includes a) to
The compound is not limited to the compounds listed in u), and organic photoconductive compounds known so far can be used. These organic photoconductive compounds can be used in combination of two or more if desired.

In addition, various pigments, dyes, and the like can be used in combination for the purpose of improving the sensitivity of the photoconductor and giving sensitivity to a desired wavelength region.

Examples of these are: 1) U.S. Pat. Nos. 4,436,800 and 4,439,506, JP-A-47-37543, JP-A-58-123541, JP-A-58-192042, and 58-2
19263, 59-78356, 60-179746, 61-148453
Monoazo, bisazo, trisazo pigments described in JP-B Nos. 61-238063, JP-B-60-5941, JP-B-60-45664, etc. 2) Metals described in U.S. Pat. Nos. 3,397,086 and 4,668,802 Phthalocyanine pigments such as phthalocyanine or metal-free phthalocyanine; 3) perylene pigments described in US Pat. No. 3,337,884; 4) indigo and thioindigo derivatives described in British Patent No. 2237680; 5) British patent Quinacridone pigments described in, for example, Japanese Patent No. 2237679, 6) British Patent No. 2237678, Japanese Patent Application Laid-Open No. 59-184348
No. 62-28738, etc. 7) Bisbenzimidazole pigments described in JP-A-47-30331, etc. 8) US Pat. Nos. 4,396,610 and 4,644,082 Squarium salt pigments described in publications, etc. 9) Azurenium salt pigments described in JP-A-59-53850 and JP-A-61-212542.

In addition, as sensitization fee, “Electrophotography” 12 9 (197
3), "Organic Synthetic Chemistry" 24 Known compounds described in No. 11 1010 (1966) and the like can be used.

Examples thereof, 10) App1ied Optics Supp1ement 3 50 (1969), JP triarylmethane dyes described in 50-39548 Patent Publication, 11) cyanine dyes described in U.S. Patent No. 3,597,196 Pat etc. , 12) JP-A-59-164588, JP-A-60-163047, JP-A-60-25251
Styryl dyes described in JP-A-7-No. 7 and the like.

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

In the photosensitive layer according to the present invention, for improving the sensitivity and the like, compounds such as trinitrofluorenone, chloranil, tetracyanoethylene, JP-A-58-65439, JP-A-58-102239, and JP-A-58-102239
Compounds described in JP-A-129439, JP-A-60-71965 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 may be used in combination. I can do it. In the electrophotographic photosensitive layer according to the present invention, it is necessary to finally remove the photosensitive layer in the non-image area. However, this step is a step of comparing the solubility of the photosensitive layer with respect to the eluate and the resist property of the toner image with respect to the eluate. Although it is determined by the relationship and cannot be expressed unambiguously, at least the binder resin is preferably a polymer compound soluble or dispersible in the above-mentioned eluate.

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 acid ester copolymer,
Styrene such as styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, vinyl acetate / crotonic acid / methacrylic acid ester copolymer, etc. Copolymers with carboxylic acid-containing monomers such as acids, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid, or monomers containing acid anhydride groups, methacrylamide, vinylpyrrolidone, phenolic hydroxyl groups And a vinyl acetal resin such as a copolymer containing a monomer having a sulfonic acid group, a sulfonamide group, or a sulfonimide group, a phenol resin, a partially saponified vinyl acetate resin, a xylene resin, and 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 when used as a photoreceptor for an electrophotographic printing plate, and can therefore be advantageously used.

As the monomer-containing copolymer having an acid anhydride group, a copolymer of styrene and maleic anhydride is preferable. Examples of the monomer-containing copolymer having a carboxylic acid group include a copolymer of styrene and maleic acid half ester, and a copolymer of acrylic acid or methacrylic acid and their alkyl ester, aryl ester or aralkyl ester. Coalescence is preferred. Also, vinyl acetate and crotonic acid are good. Preferred in phenolic resins are phenol, o-cresol, m-cresol, and p-
A novolak resin obtained by condensing cresol with methanal or ethanal under acidic conditions can be mentioned.
The binder resin may be used alone or in combination of two or more.

When a photoconductive compound and a binder resin are used, the sensitivity becomes low when the content of the photoconductive compound is small, so that it is 5 parts by weight or more, more preferably 100 parts by weight of the binder resin. It is preferable to use a mixture of 15 parts by weight or more. In addition, when the photosensitive layer thickness is small, the charge required for toner development cannot be charged, and when the photosensitive layer thickness is too large, not only the deterioration of the eluate is promoted, but also a side etch is induced at the time of elution, and a good image cannot be obtained. Therefore, 0.1 to 30 μm, more preferably 0.5 to 10
μm is good.

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 producing the photosensitive layer, a method for containing the components constituting the photoconductive layer in the same layer, or a method for separately containing two or more layers, for example, different charge carrier generating materials and charge carrier transport materials A method of separating the layers and using the layers is known, and any method can be used. The coating liquid is prepared by dissolving each component constituting the photoconductive layer in an appropriate solvent, but when using a component insoluble in a solvent such as a pigment, a ball mill, a paint shaker, a dyno mill, an attritor, etc. It is used by dispersing to an average particle size of 0.01 to 5 μm by a disperser. The binder resin and other additives used in the photoconductive layer can be added during or after the dispersion of the pigment or the like. An electrophotographic lithographic printing plate is prepared by applying the coating solution prepared in this manner 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. Can be obtained.
Examples of the solvent for the coating solution include halogenated hydrocarbons such as dichloromethane, dichloroethane, and chloroform; alcohols such as methanol and ethanol; ketones such as acetone and 2-butanonecyclohexanone; ethylene glycol monomethyl ether; and 2-methoxyethyl acetate. Glycol ethers, oxolane, oxane,
Cyclic ethers such as dioxane; esters such as 1-propyl acetate and butyl acetate;

In the photoconductive layer, if necessary, in addition to the photoconductive compound and the binder resin, for the purpose of improving the film properties such as the flexibility of the photoconductive layer and the coated surface, a plasticizer, a surfactant, and other Additives can be added. Examples of the plasticizer include biphenyl, biphenyl chloride, o-terphenyl, p-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, and triphenylphosphoric acid.

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. Examples of the exposure method include reflection image exposure using a xenon lamp, a tungsten lamp, a fluorescent lamp, or the like as a light source, contact exposure through a transparent positive film, and scanning exposure using a laser beam, a light emitting diode, or the like. When performing scanning exposure, use He-Ne laser, He-Cd
Scanning exposure with laser light source such as laser, argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, semiconductor laser such as GaAs / GaAlAs, InGaAsP, alexandrite laser, copper vapor laser Alternatively, the exposure can be performed by scanning exposure using a light emitting diode or a liquid crystal shutter (including a line printer type light source using a light emitting diode array, a liquid crystal shutter array, or the like).

Next, the electrostatic latent image is developed with 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 developing method is suitable for producing a printing plate with which a fine toner image can be formed and which has good reproducibility. Further, positive / positive development by positive development and negative / positive development by reversal development under application of an appropriate bias voltage are also possible. 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 area photosensitive layer is removed with an eluent to produce a printing plate.

The toner according to the present invention needs to contain a resin component having resist properties to the eluate. Examples of the resin component include methacrylic acid, acrylic acid, and acrylic resins composed of these esters, vinyl acetate resin, copolymers of vinyl acetate with ethylene or vinyl chloride, vinyl chloride resin, vinylidene chloride resin, polyvinyl butyral Vinyl acetal resin, such as polystyrene, copolymers of styrene with butadiene, methacrylate, etc., polyethylene, polypropylene and its chlorides, polyester resins such as polyethylene terephthalate and polyethylene isophthalate, polycapramid and polyhexamethylene adipamide Such as polyamide resins, phenolic resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, gelatin, cellulose ester derivatives such as carboxymethylcellulose,
Other examples include wax and wax.

In addition, the toner may contain a dye or a charge controlling agent as long as the toner does not adversely affect development and fixing.

(E) 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 present invention.

Example 1 A JIS1050 aluminum sheet was immersed in a 10% NaOH aqueous solution at 60 ° C., and was etched so that the amount of aluminum dissolved was 6 g / m ² . After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize, and sufficiently washed with water. Thereafter, electrolytic surface roughening was performed in a 0.7% aqueous nitric acid solution for 20 seconds, and the surface was washed by immersion in a 20% aqueous sulfuric acid solution at 50 ° C., followed by washing with water. In addition, 20%
An anodizing treatment was carried out in a sulfuric acid aqueous solution, followed by washing with water and drying to prepare a printing plate support.

The surface of the support is treated with a paint shaker.
The following photosensitive composition dispersed in time was applied by 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 / m ² .

Photosensitive layer coating liquid composition Butyl methacrylate / methacrylic acid copolymer 18 weight (molecular weight 50,000, acid value 200) metal-free phthalocyanine 4 weight 1-butyl acetate 60 weight 2-propanol 18 weight The obtained printing plate precursor was placed in a dark place. After applying a corona discharge to charge the surface potential (V ₀ ) to about +300 V, a scanning image is exposed using a semiconductor laser (780 nm), and a positively charged toner (LOM, manufactured by Mitsubishi Paper Mills, Ltd.) -EDIII), the toner was heat-fixed to obtain a toner image on the photosensitive layer.

Next, aqueous sodium silicate solution (SiO ₂ 30%, SiO ₂ / Na ₂
The eluate was prepared by diluting 20 parts by weight of O) and 1.0 part by weight of potassium hydroxide with pure water to 100 parts by weight, and the compounds shown in Table 1 and, if necessary, hydrochloric acid or an aqueous solution of sodium hydroxide were added in advance. Washing solution (20dm
^{Using 3} ), up to 1000 sheets of continuous plate making (A2 plate) were performed until the pH of the washing solution reached 10.5.

The evaluation of the washing liquid was performed as follows.

<Evaluation of ability to suppress dissolution progress> The non-dissolved printing plate after toner development was immersed for 10 seconds and 30 seconds in the circulating reuse washing solution after the plate making process was completed, and immediately washed with pure water. Evaluate the extent of elution of the layer.

1: Not eluted at all.

2: No elution at 10 seconds, but the photosensitive layer surface is slightly eluted at 30 seconds. 3: The photosensitive layer surface is eluted at 10 seconds (elution rate less than 5%). 5 to 50%, 5: elution rate> 50%, <Evaluation of water washing solution> The water washing solution during and after the printing of the 1000 plate was filtered through a # 325 mesh wire mesh, and the filtrate was filtered. The liquid change and the remaining residue (aggregate) after standing still for 5 days were evaluated.

A: No aggregation and no gelation of the liquid occurred until the end of the printing. B: No aggregation or gelation occurred during mail order, but gelation occurred on the 5th day at the latest. C: Aggregation and / or Table 2 shows the occurrence of gelation, water washing conditions (compound concentration) and the obtained results.

With a water-only washing solution (test No. 8), the solution is relatively early in plate making.
The pH increased, and if the plate making was further continued, the side etch deteriorated, and image (thin line) reproducibility was not obtained. In addition, in the case of a washing solution containing a compound having no acid dissociation index (pKa) in the range of 7.0 to 10.5 (Test Nos. 6 and 7), although the pH rise becomes considerably slower than that of water alone, As the pH increased, the side-etching progressed in the washing section, and at the same time, the stability of the washing liquid itself was lost, and the washing liquid gelled immediately. On the other hand, as can be seen from Table 2, at least 7.0 to 10.5
The washing solution (Test Nos. 1 to 5), to which a compound having one of the acid dissociation indexes (pKa) was added, suppressed the increase in pH by adding a relatively small amount, and caused aggregation and gelation even with time. Without
Stable plate making was achieved. In particular, the system according to the present invention in which an amino acid having one of the acid dissociation indices (pKa) was added to at least 7.0 to 10.5 (Test Nos. 1, 2, and 4) also exhibited excellent elution suppressing ability. .

Example 2 Water was used as a washing liquid under the same plate making conditions as in Example 1,
At the time of 100 printing (washing solution pH 0.1), an arginine aqueous solution was added so as to be 0.80% by weight based on the washing solution.
When plate making was performed for a total of 1000 plates, the plate making was completed without any problem similarly to the test No. 2 in Example 1. Similarly, when glutamic acid and p-hydroxybenzoic acid (pH adjusted with sodium hydroxide, respectively) were added, good results were obtained.

Example 3 Water was used as a washing liquid under the same plate making conditions as in Example 1,
At the time of 100 editions, 0.20% by weight of an aspartic acid aqueous solution whose pH was adjusted with potassium hydroxide was added in terms of solid content.
I made 100 plates, but I was able to make plates stably until the end.

Example 4 Example 1 5% by weight of the washing liquid prepared in plate No. 1000 in Test No. 2
After adding 4 dm ^{3 of the} aqueous serine solution, plate making was further performed for 1000 plates. Although the elution inhibiting ability was slightly deteriorated, plate making was completed without any major problem. Similarly, a 20% by weight aqueous solution of glycine (adjusted to pH = 7.5 with lithium hydroxide) was added to the water washing solution prepared in plate No.1000 in Example 1 test No.4, and then the plate was prepared in plate No.1000. Plate making could be performed while maintaining the liquid properties.

Example 5 Example 1 Example 1 was repeated except that 20 ppm of a preservative, 2-methylisothiazolin-3-one, was further added to the washing solution of Test No. 1.
The plate making was performed under the same conditions as described above. As a result, plate making could be performed without any adverse effect on the properties of the washing liquid and the plate making.
A 2-methylisothiazolin-3-one-added system was used except that 1,2-benzolthiazolin-3-one and hydroxyethyl-S-triazine (25 ppm each) were used instead of 2-methylisothiazolin-3-one. Plate making was performed in the same manner as described above, and similar results were obtained.

(F) Effect of the Invention According to the method of the present invention, it is possible to prolong the replacement period of the washing liquid without generating aggregates in the washing tank and suppressing deterioration of side etching and the like.

Claims (3)

(57) [Claims] 1. A lithographic printing method in which an electrophotographic lithographic printing plate on which a toner image is formed by an electrophotographic method is brought into contact with an alkaline eluent using an automatic dissolution machine, and then washed with a washing solution to be recycled. In a plate making method, a lithographic plate is characterized in that the washing solution finally contains an amino acid having an acid dissociation index (pKa) of at least 7.0 to 10.5 or a salt thereof, and the pH is kept at 10.5 or less. How to make a printing plate. 2. A lithographic printing plate making method according to claim 1, wherein an aqueous solution containing said organic compound and having a pH adjusted to 9.5 or less is added to said washing liquid according to the throughput of said lithographic printing plate. Method. 3. The method for making a lithographic printing plate according to claim 1, wherein said washing liquid further contains at least one of a preservative and a bactericide.