JPH0544033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a method for correcting a printing plate, in which a toner image is formed by electrophotography using an organic photoconductive compound, and a photosensitive layer other than the toner image forming area is etched. This invention relates to a method for making printing plates that are made by plate making.

Many electrophotographic printing plates using organic photoconductive compounds are already known.
No. 38-6961, No. 41-2426, No. 46-39405
No., JP-A No. 50-19509, No. 50-19510, No. 54-
No. 19803, No. 54-89801, No. 54-134632, No. 54
-145538, 55-105254, etc. According to a general plate-making method, a toner image is formed on an electrophotographic original plate using an organic photoconductive compound by a normal electrophotographic method, and then a non-image area other than the toner image is removed using an alkaline agent. The plate is made by treating it with an etching solution.

As the toner used for image formation, both so-called dry toner and wet toner can be used, but in order to obtain printed matter with excellent resolution, wet toner using a liquid development method is far more preferable.

In the above-mentioned electrophotographic printing plates, which are made using the difference between the etching properties of the toner and the photosensitive layer, the toner is not etched at all, except for the areas to which the toner is attached, regardless of whether it is a dry toner or a wet toner. By quickly etching only the photosensitive layer portion, high quality printed matter with good fine line reproducibility can be obtained.

The toner must not only be non-etchable and therefore resistant to etching, but also be hydrophobic, ink-receptive, and have sufficient adhesion to withstand multiple printings. . On the other hand, the photosensitive layer is much more easily etched than the toner, and while it is required that it not be excessively etched, on the other hand, after etching,
It must have strong film-forming properties that can retain toner to the extent that it can withstand printing on a large number of sheets.

Examples of the binder for the photosensitive layer having such characteristics include styrene maleic anhydride copolymer, maleic acid ester resin, vinyl acetate-crotonic acid copolymer, vinyl acetate-maleic anhydride copolymer,
These binders include acrylic esters, methacrylic esters, and phenolic resins.
High molecular weight, preferably about 30,000 to about 300,000
A material having a high acid value, preferably about 80 to about 300, is particularly suitable because it can be etched with an alkaline aqueous solution.

In the above-mentioned printing plates, the etched areas usually expose the surface of the hydrophilic support and become ink repellent. If the etching is incomplete and the photosensitive layer binder remains, the binder is usually oleophilic or
This is inconvenient because it indicates ink receptivity. Incidentally, the so-called correction operation, in which unnecessary image areas generated on a printing plate obtained by photolithography are treated with an appropriate treatment liquid to make them ink repellent, is an important operation. The areas that need to be corrected include those that already exist in the original, those that occur during exposure, and those that result from other non-uniform development processes. i.e., if there are unwanted images in the reproduced original, if there are dust and dirt, particulates, fingerprints or other contamination, or if the original is made by pasting together various originals. , shadows may appear during exposure. In order to obtain good printed matter, all of these points must be corrected at the plate-making and printing stages.

What is required for correction of printing plates is that the operation is simple, that the correction is reliable, that there is no problem with the printing properties of the base material, etc., and that there is no possibility that defects may affect adjacent image areas. These include not being printed, and the correction effect lasting. An object of the present invention is to provide a plate-making method that satisfies the above requirements as a correction method.

In the present invention, a printing original plate having a photosensitive layer containing an organic photoconductive compound and a binder that can be etched with an alkaline aqueous solution on a conductive support having a hydrophilic surface is etched against an etching solution by an electrophotographic method. After forming a toner image having resist properties, correcting with a correction liquid so as not to substantially dissolve the photosensitive layer binder and to dissolve and remove unnecessary toner image portions at least to the extent that they do not have resist properties; The plate-making method then involves processing with an etching solution containing an alkaline agent to remove the photosensitive layer in non-image areas other than the toner image.

One of the features and advantages of the present invention is that correction fluid can be applied depending on the situation of the unwanted toner image to be corrected. Not substantially dissolving the photosensitive layer binder means that it may be dissolved to the extent that the hydrophilic surface of the support is not substantially exposed, and the photosensitive layer binder may be dissolved as the toner is dissolved. The correction fluid may be a correction fluid that allows some degree of dissolution or removal of. Such a correction liquid with a high dissolving power is suitable when there is no necessary toner image area around the area or when the area to be corrected is large. If the binder of the photosensitive layer is completely dissolved, the toner will not enter or adhere to the hydrophilic surface of the support, for example, the fine pores provided by anodization on the aluminum support, even after subsequent etching treatment. The toner image may not be etched, resulting in ink stain defects, and there is also a greater risk that the photosensitive layer beneath the adjacent toner image will also be dissolved.

Furthermore, dissolving and removing the toner to such an extent that resist properties cannot be obtained does not only mean that the toner to be corrected can be completely dissolved and removed, but even if the toner is not sufficiently dissolved and removed, the subsequent etching process may This includes the fact that the photosensitive layer beneath the toner is etched away and no resist of the toner is formed. Even a correction liquid having a relatively low ability to dissolve toner can be completely corrected by the subsequent etching process, and has the advantage that it is also possible to correct areas where adjacent toner images exist. There is.

The unnecessary toner image is dissolved by the subsequent etching process at least to the extent that resist properties are lost, and the photosensitive layer binder under the toner image is dissolved at most to the extent that the surface of the hydrophilic support is not exposed. A good correction fluid is highly dependent on the combination of the type of toner and the type of photosensitive layer binder, but one skilled in the art can find a suitable correction fluid by simple experimentation.

Examples of liquids that can be used depending on the combination of toner type and photosensitive layer binder include aromatic hydrocarbon solvents such as benzene, toluene, and xylene, and halogenated hydrocarbon solvents such as trifluoroethylene and methylene chloride. Solvents, ketone solvents such as acetone and methyl ethyl ketone, furan solvents such as tetrahydrofuran, ether solvents such as ethyl butyl ether and ethylene glycol monomethyl ether, n-hexane, n-octane, n-decane, n-dodecane, isoheptane, isononane , isododecane and their mixtures Isopa-E, Isopa-G, Isopa-H (all are trade names of isoparaffinic solvents manufactured by Etsuso Petrochemicals), Ciel Sol 71 (trade names of isoparaffinic solvents manufactured by Ciel Petrochemicals) ), ligroin, mineral spirits, aliphatic hydrocarbon solvents such as kerosene, n-butyl acetate, z-ethylhexyl acetate,
Examples include ester solvents such as ethylene glycol monomethyl ether acetate, ethyl lactate and n-butyl lactate, and these may be used singly or in a mixture of two or more depending on the type of toner and the type of photosensitive layer binder. I can do it.

Particularly preferred correction fluids are water-miscible organic solvents such as ketone solvents, furan solvents, alcohol solvents such as butanol, benzyl alcohol, etc.
This product has the advantage that even if it is treated with an aqueous alkaline etching solution immediately after the correction process, the correction and etching processes can be performed uniformly and quickly.

Examples of toners that meet the above-mentioned requirements used in the present invention include styrene resins, acrylic resins, polyester resins, and epoxy resins. Further, it is practically preferable to contain pigments and dyes for coloring, and a charge control agent within a range that does not adversely affect the safety and fixing properties of the toner.

In the electrophotographic printing plate used in the present invention, it is preferable to use a photosensitive layer binder containing an organic photoconductive compound that has a large molecular weight and a large acid value. Molecular weight is about 30,000 or more, preferably about 5
300,000 to about 300,000, acid value is about 80 or more, preferably about 100
~300 things.

Examples of the organic photoconductive compound used in the printing plate used in the present invention include the following compounds.

(a) Aromatic tertiary amino compounds: triphenylamine, diphenylbenzylamine, di-(β-
naphthyl) benzylamine, diphenylcyclohexylamine, etc.

(b) Aromatic tertiary diamino compound: N, N, N',
N'-tetrabenzyl-P-phenylenediamine, N,N,N',N'-tetrabenzylbenzicine, 1,1'-bis-(4-N,N-dibenzylaminophenyl)-ethane, 2,2-bis-
(4-N,N-dibenzylaminophenyl)-butane, bis-(4-N,N-di-(P-chlorobenzylaminophenyl))-methane, 3,3-diphenylallyridine-4 ,4'-bis(N,N-
diethyl-m-toluidine), 4,4'-bis(di-p-tolylamino)-1,1,1-triphenylethane, etc.

(c) Aromatic tertiary triamino compound: 4,4',
4″-tris(diethylaminophenyl)methane, 4-dimethylamino 4,4″-bis(diethylamino)-2,2″-dimethyl-triphenylmethane, etc.

(d) Main condensation product: condensation product of aldehyde and aromatic amine, reaction product of tertiary aromatic amine and aromatic halide, poly-p-phenylene-1,
3,4-oxadiazole, a reaction product of formaldehyde and a condensed polycyclic compound, etc.

(e) Metal-containing compounds: 2-mercapto-benzothiazole zinc salt, 2-mercapto-benzoxazole lead salt, 2-mercapto-6-methoxybenzimidazole-lead salt, s-hydroxy-
Quinoline-aluminum salt, 2-hydroxy-
4-methyl-azobenzene-copper salt, (f) polyvinylcarbazole compound: polyvinylcarbazole, halogen-substituted polyvinylcarbazole, copolymer of vinylcarbazole and styrene, copolymer of vinylanthracene-vinylcarbazole, etc.

(g) Heterocyclic compound: 1,3,5-triphenyl-
Pyrazoline 1-phenyl-3-(p-dimethylaminostyryl)-5-(p-dimethylaminophenyl)-pyrazoline, 1,5-diphenyl-
3-styryl-pyrazoline, 1,3-diphenyl-5-styryl-pyrazoline, 1,3-diphenyl-5-(p-dimethylaminophenyl)-
Pyrazoline, 3-(4′-dimethylaminophenyl)-5,6-di-(4″-methoxyphenyl)-
1,2,4-triazine, 3-(4'-dimethylaminophenyl)-5,6-dipyridyl-1,
2,4-triazine, 2-phenyl-4-
(4′-dimethylaminophenyl)-quinazoline,
6-hydroxy-2,3-di(p-methoxyphenyl)-benzofuran, 2,5-bis-[4'-
ethylamino-phenyl-(1')]-1,3,4
-Oxadiazole etc.

The organic photoconductive compound used in the present invention can also be used for good printing using pigments such as phthalocyanine pigments, quinacridone pigments, indigo pigments, cyanine pigments, perylene pigments, bisbenzimidazole pigments, quinone pigments, azo pigments, and indigo pigments. You can get the version.

As the base for the printing plate in the present invention, all conventionally known bases for printing plates can be used. For example, metal plates such as aluminum plates, zinc plates, magnesium plates, copper plates, etc. Films and synthetic papers made of polyester, cellulose acetate, polystyrene, polycarbonate, polyamide, polypropylene, etc. Examples include processed paper such as resin-coated paper, but the photoconductive compound and binder are removed by etching after image formation, and the non-image area must have hydrophilic properties, so hydrophobic The base having a surface needs to be hydrophilized in advance. A metal plate, especially an aluminum plate, is most suitable, but surface treatments such as graining, alkali treatment, acid treatment, and anodization are preferred. In the case of films, it is preferable to coat them with a relatively highly hydrophilic polymer compound and perform crosslinking treatment, or to vapor-deposit or bond them with a certain type of metal.
When using an insulating base, it is necessary to perform conductive treatment on the base surface.

To produce a printing original plate, the photoconductive compound and binder are dissolved in a solvent (if the photoconductive compound is not dissolved, a dispersion liquid is prepared using a colloid mill, homogenizer, ultrasonic dispersion machine, etc.). ,
A sensitizing dye etc. is added to the support to a thickness of 1~
Apply to a thickness of 30μ and dry. The ratio of the photoconductive compound to the binder is 0.01 to 50 parts by weight, preferably 0.2 to 10 parts by weight, depending on the binder and photoconductive compound used, per 1 part by weight of the photoconductive compound. It is.

Those that can be used as solvents include all organic solvents that are capable of dissolving the binder and dissolving or dispersing the photoconductive compound.

The etching solution used in the present invention includes sodium hydroxide, potassium hydroxide,
Inorganic alkaline agents such as sodium silicate, potassium silicate, trisodium phosphate, dibasic sodium phosphate, trisium ammonium phosphate, sodium metasilicate, sodium carbonate, ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine , Alkylamines such as diethylamine, triethylamine, monoisopropylamine, diisopropylamine, n-butylamine, amino alcohols such as mono-, di- or triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylene amine There are organic amine compounds such as , ethylenediamine, and pyridine. Preferred are alkali metal hydroxides and amino alcohols. The amount of alkaline agent is
The range is approximately 0.05 to 10% by weight.

The etching solution used in the present invention may further contain alcohols such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, benzyl alcohol, phenethyl alcohol, and polyethylene glycol, if necessary.

Examples will be described below, but the present invention is not limited thereto.

Example 1 100 g of butyl methacrylate-methacrylic acid having a molecular weight of 120,000 and an acid value of 150 was dissolved in a mixed solvent of 500 g of xylene and 200 g of butanol to prepare a binder solution. In this solution, 70% of 1,3,5-triphenylpyrazoline was added as an organic photoconductive compound.
g dissolved and 1% of Rhodamine B as a sensitizing dye.
Add 50g of DMF solution and make 1000g of xylene.
Adjusted to. The coating was applied to a grained and anodized aluminum plate of 100 μm to a solid content of 5 g/m ² and dried to obtain a printing original plate.

After the obtained printing original plate was positively charged by applying a corona discharge of -6 kV in a dark place, the halftone dot image was exposed to white light. Immediately, development was performed using MRP liquid toner manufactured by Ricoh Co., Ltd., and heat fixation was performed using a fuser.

Next, unnecessary portions of the toner image were dissolved with xylene and gently wiped to remove the toner. After drying, immerse in the following etching treatment solution (10 seconds at 25℃)
and washed with running water. Both the photosensitive layer in the non-image area and the photosensitive layer in the unnecessary toner area were completely etched, and it was possible to print more than 20,000 sheets without any background smearing without any printing troubles.

Example 2 Monoethanolamine 50g Benzyl alcohol 30g Water 1000g Example 2 The same procedure as in Example 1 was repeated except that Cielsol 71 was used in place of xylene and unnecessary toner images were processed. Similar results were obtained.

Example 3 Example 1 was repeated using a printing original plate prepared in the same manner except that a vinyl acetate-crotonic acid copolymer having a molecular weight of 150,000 and an acid value of 180 was used as the binder for the organic photoconductive compound. Exactly similar results were obtained.

Example 4 The same procedure as in Example 3 was carried out except that the original printing plate was modified with kerosene. The same results were confirmed.

Example 5 The original printing plate of Example 3 was modified with a mixture of benzyl alcohol and acetone (1:2 volume ratio) and immediately immersed in the etching solution of Example 1. It was confirmed that the correction and etching processes could be performed quickly and satisfactorily.

Claims (1)

[Claims] 1. A printing original plate having a photosensitive layer containing an organic photoconductive compound and a binder that can be etched with an alkaline aqueous solution is placed on a conductive support having a hydrophilic surface, and is resistant to an etching solution by an electrophotographic method. After forming the toner image having the above, correct it with a correction liquid so as not to substantially dissolve the photosensitive layer binder and to dissolve and remove unnecessary toner image portions at least to the extent that they do not have resist properties;
A plate-making method in which the photosensitive layer in non-image areas other than the toner image is then removed by treatment with an etching solution containing an alkaline agent.