DE3132331A1 - METHOD FOR PRODUCING A PRINT PLATE - Google Patents

Description

Applicant: - 2 - T 52 868

Konishiroku Photo Industry Co., Ltd.
No. 26-2 Nishishinjuku 1-chome
Shinjuku-ku

Tokyo / Japan

Method of making a printing plate

The invention relates to a method for the production of printing plates and in particular to a method that can be carried out in an improved manner Method of making printing plates suitable for making duplicates of printing plates, that can withstand the printing of numerous copies.

As a general method of making off-set printing plates a plate-making process was used in which a negative or positive pilm was made which was subsequently in contact with a presensitized plate (hereinafter referred to as PS plate negative type or with a positive type PS plate subjected to image-form exposure is to be brought, whereupon it is processed in a given developer solution, whereby the Hichtbildflache is solved for removal. However, since actually the method from making an express, the Exposure of a PS plate by the PiIm to light and the development of the PS plate were a disadvantage the economy, time and cost of producing multiple printing plates are unavoidable. aside from that Electronic distribution systems are becoming practical today

is realized, even in the field of message printing, due to the extensive and varied application possibilities of computers, whereby a method for recording electrical signal information images is practically applied to a PiIm or a printing plate material by means of a laser beam. With the electronic Dissemination system is the system of recording on a 3FiIm by means of a laser beam due to the film development and the exposure of the PS plate Light in the speed of the direct system of manufacture of plates underneath. At present, the direct system for making panels in which a Imaging plate material is exposed directly by means of a laser beam, the best way for rapid production of printing plates. The direct system for making panels has now been developed by ECOM Inc. and of LogEtronic Inc. commercially exploited whose products are suitable for printing plates without the stage of manufacture to generate any negative. However, when making several printing plates, the Method of writing on each of the printing plates by means of a laser beam Problems related to the Speed and cost due to the required sampling time of at least the order of seconds per A2 side, the life of the laser tube and the Need for printing plate materials that are sensitive to laser beams. With such a Situation in the field of mass printing, there has long been a need to solve the problem, how quickly and how inexpensively several duplicate plates can be produced from one printing plate obtained by laser running drawing.

As for the creation of duplicate disks, "so" describes the JA Laid-Open Patent Publication (hereinafter referred to as JA-OS) Hp. 100005/1978 a process for the production of printing plates, which therein exists, an ink receiving layer by the offset printing process on an aluminum plate that undergoes anodic oxidation (hereinafter referred to as AD treatment designated) and, in addition, describes the JA-OS Ur. 46973/1980 a case for the production of multiple printing plates, which consists of lithographic plates for mass printing to produce by duplicate printing using a stencil plate or master plate, which by laser beam recording was obtained. These methods reproduce lithographic plates like offset printing forming an image using a special color on a printing plate material in! sheet form, like an aluminum plate, in which the ink printed on the aluminum plate is an integral part the duplicate plate is used for printing. In general, offset lithographic printing is based on the principle that if the surface of a printing plate after moistening its Mcht image area with water, is provided with an oily printing ink, the moistened Mcht-Bildf lache repels the oily printing ink, so that the Printing ink only adheres to the oleophilic image. To a maintain accurate reproduction and homogeneity of a printed image, the balance between the ink and the dampening water must be well controlled at the time of printing will. An insufficient supply of dampening water or an excessive supply of the printing ink causes malfunctions in the production of a printed image, such as ink stains on the non-image surface, defacement of details

and a point growth phenomenon by bold points ", In duplicate plates with these provided with printing inks ! "laugh as oileophile surfaces exercise the bond strength between the printing ink component formed on the aluminum plate and the aluminum plate itself, as well as the abrasion resistance of the printing ink compositions and the amount of ink applied has a great influence on the life under pressure of the Duplicate disk. An increase in the amount of ink to extend the press life of the duplicate plate adversely affects the accurate reproduction of an image as mentioned above, thereby causing the disadvantage of the methods. gives.

One such disadvantage is the build up of a lot of ink Not allowed on the printing plate, not just in the Case of off-set printing, but also in the case of the production of duplicate plates from a relief ~ scraping ~ ion or. Master printing plate. Used in the Eelief printing process If a large amount of printing ink is applied, the printing ink is pressed out at the edge of the relief part, resulting in a deterioration in the production image quality leads.

The aluminum plate for use in the production of several printing plates is _- if it has not been treated to make it hydrophilic, it is highly oleophilic and if some oleophilic material is applied or if fingerprints are left on the plate, printing ink is deposited on this part, which sometimes leads to plekening led. The holes on the surface of the aluminum plate that has undergone AD treatment are active and when left in the open air can sometimes occur in the course of the

Time a change occurs so that it becomes a factor which makes the plate unstable when used as a printing plate. Indicates certain errors to the disk the surface, so can the errors in the image reproduction lead to malfunctions. Therefore, users need to carefully handle the aluminum plate respect, think highly of.

It is therefore an object of the invention to provide one A method of making a printing plate suitable for making a plurality of duplicate lithographic printing plates as well as the provision of a process for duplication or duplication in printing mode, of lithographic printing plates which have longer press life and improved Have image reproducibility as well as manageability. Other objects of the invention are can be seen from the description below.

The object of the invention can be achieved by manufacturing a printing plate so that an image from a printing ink is formed on a resin layer formed on a printing plate material, and that the resin layer in the proportion in which the image is not formed from the printing ink, with a solvent for the resin is resolved.

Printing plate materials useful in the present invention include paper made with plastic materials is coated, such as. B. polyethylene, polypropylene, polystyrene and the like; Plates of metals, such as z. B. aluminum (including aluminum alloys), zinc, chromium, copper and the like; Plastic films,

like ζ. Β. Cellulose diacetate, cellulose triacetate, cellulose peopionate, Cellulose butyrate, polyethylene terephthalate, Polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal and the like; and papers or plastic - Films coated or vacuum evaporation coated with the above metals. From these materials According to the invention, it is best to use an aluminum plate used because of their high dimensional stability as well as their low cost. Likewise A composite film can be used favorably in accordance with the invention, like a polyethylene terephthalate film with a Aluminum foil is coated as in the JA patent publication No. 18327/1973.

The printing plate material used in the present invention can before it is provided with a resin layer, subjected to a suitable surface treatment. For example, in 3? All one! Carrier with a plastic surface the carrier is subjected to a treatment such as a chemical treatment, a Discharge treatment, flame treatment, ultraviolet ray treatment, high frequency treatment, glow discharge treatment, active plasma treatment, laser treatment and the like.

One of the most preferred printing plate materials that can be used in accordance with the present invention used is one whose surface is made of aluminum (including aluminum alloys) that has been subjected to mechanical graining treatment such as spherical graining, sandblasting, brush graining and the same; Grain Post Treatment by chemical graining or electrolytic graining; smoke treatment in an aqueous solution of sodium silicate,

Potassium fluorozirconate, phosphoric acid salts and the like or such a surface treatment as anodic oxidation. As described in U.S. Patent 2,714,066 It is also advisable to use an aluminum plate after the graining treatment and then the AD treatment in an aqueous solution of sodium silicate was dived. The above-mentioned AD treatment is carried out, for example, by applying an electric one Current through an aluminum plate as an anode in one. Electrolytes made for use alone or in Combination of two or more organic acids, such as oxalic acid, sulfamic acid and the like, or one aqueous or non-aqueous solution of these acids.

The resin layer formed on the printing plate material used in the present invention should be one be those caused by a solvent except for the formed image area covered with a printing ink can be removed and should have excellent adhesion to the printing plate.

A resin for use in forming one Resin layer regardless of whether it is water-insoluble or water-soluble, should be water-insoluble due to IOtopolymerization and the like, at least at the time of the subsequent Printing process and; should be selected from those which are soluble in a solvent which the Protective layer not etched, which was produced by coating the printing ink used according to the invention.

Such resins include, for example, acrylic acid copolymers, as well as homopolymers or double, tri- or multiple copolymers of N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, N ~ (4-hydroxynaphthyl) methacrylamide,

ο-, m-, p-hydroxystyrene, ο-, m-, or p-hydroxyphenyl methacrylate, α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic anhydride; Alkyl acrylates such as Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, Amyl acrylate, hexyl acrylate, octyl acrylate, 2-chloroethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate and N-dimethylamino ethyl acrylate; Alkyl methacrylates such as methyl methacrylate, Ethyl methacrylate, propyl methacrylate, butyl methacrylate, Amyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 4-Hydroxybutyl methacrylate, glycyl methacrylate and N-dimethylaminoethyl methacrylate; Acrylamides or methacrylamides such as acrylamide, methacrylamide, H-methylolacrylamide, U-methylol methacrylamide, H-ethyl acrylamide, N-hexyl methacrylamide, H-cyclohexyl acrylamide, U-Hydroxyäthylacrylamid, IT-Phenylacrylamid, N-Uitrophenylacrylamid and N-ethyl-N-phenyl acryl amide; Ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, Propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, various phenyl vinyl ethers; Vinyl ester like Vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate; Styrenes such as styrene, α-methylstyrene, methylstyrene and chloromethylstyrene; Vinyl ketones such as methyl vinyl ketone, Ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone; olefins such as ethylene, propylene, isobutylene, butadiene and isoprene;

of N-vinylpyrrolidone, N-vinylcarbazole, 4-vinyl pyridine, acrylonitrile and methacrylonitrile; p-substituted phenol-formaldehyde resins (such as p-t-butylphenol-formaldehyde resin), m-cresol-formaldehyde novolak resins, Methacrylic acid copolymers, acrylamide copolymers, Methacrylamide copolymers, vinyl pyrrolidone copolymers, Shellac, epoxy resins, polyamide resins, polyurethane resins, urea resins and the like. Resins according to the invention

are suitable can be selected from such resins, however, are not limited to this ". The resin layer, which is formed on the! printing plate according to the invention, should contain some of the resins described above - and apart from that they can contain a plasticizer, Dyes, surfactants and the like.

The resin layer of the present invention may have a resin layer a matrix structure made by application with an emulsion whose dispersoid contains, for example Yinylacetate-ethylene copolymer, poly (methyl acrylate), Poly (ethylacrylate), polyacrylonitrile, polyvinyl acetate, diacetone-acrylamide-methyl acrylate copolymer, diacetone-acrylamide-acrylonitrile copolymer, Diacetone-acrylamide-vinyl acetate copolymer, methyl acrylate-vinyl acetate copolymer, Methyl acrylate-vinyl chloride copolymer, methyl acrylate-styrene copolymer, Ethylene-methacrylic acid copolymer, acrylonitrile-butadiene copolymer, Acrylonitrile-styrene copolymer. The mean particle diameter of the matrix material is conveniently no more than 15yum or yu. the The emulsion may optionally contain a protective colloid, surfactant, plasticizer, and colorants.

The above plasticizer is needed to achieve it a desired plasticity of the resin, the Plasticizers, for example, include dimethyl phthalate, diethyl phthalate, Dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, Ethyl captylphthalat, di cyclohexylphi hai at, Ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, Diaryl phthalate; Glycol esters such as ethyl phthalyl ethyl glycolate, Butyl phthalyl butyl glycolate, triethylene glycol dicaprylic acid ester; Phosphates such as tricresyl phosphate,

Triphenyl phosphate; aliphatic «dibasic acid esters such as diisobutyl adipate, dioctyl adipate, dimethyl sebacate, Dibutyl sebacate, dioctyl azelate, dibutyl fumarate, and the like; Polyglycidyl methacrylate, trimethyl citrate, Glycerine triacetyl ester "and butyl laurate.

The above surfactant improves the Removability of the ITicht image area of the resin layer for Time of development and is effective for evenly coating the resin layer on the printing plate. However, the addition of an excess henge des Means to be avoided, otherwise it has a bad influence on the press life of the printing plate. The agent can be selected from anionic surfactants, cationic surfactants Agents, nonionic surfactants, and amphoteric surfactants and beyond fluorinated surfactants can also be used.

The above-mentioned dye or coloring agent is suitable for assessing the removability of the Non-image area of the resin layer during the itz treatment; the coloring agent includes organic or inorganic dyes or pigments such as acridine dyes, merocyanine dyes , Cyanine dyes, styryl dyes, triphenylmethane dyes, Copper phthalocyanine dyes, Buss, titanium oxide, quinone imino dyes.

As the resin layer according to the invention, for example, conventionally known resin compositions from photosensitive « borrowed negative type can be used. Therefore, usually used PS plates of the lithographic negative type

as a printing plate according to the invention with a resin layer can be used on the plate material. In such a pail, an ink that can be used in the developing solution for the photosensitive resin composition is not soluble, can be used to so to get duplicate printing plates from a stencil or master plate. To the by aqueous developer or alkaline developer processable photosensitive Negative type resin compositions can employ a commonly used oleophilic off-set printing ink will. If the test color additions an ink composition suitable for transmission of light is that for photosensitive Resin composition is active, so that allows Ink composition by applying post exposure after the development the production of duplicate printing plates, which are resistant to printing a much larger number of eopias. As the resin layer according to the invention, for example conventionally known photosensitive resin compositions positive type can be used. Therefore, commonly used PS plates of the positive lithographic type can be used as a printing plate according to the invention having a resin layer on the printing plate material. In in this case, the photosensitive resin composition should be exposed to light active therefor before development will.

The resin layer according to the invention can either consist of a Layer or two or more layers and can also be either photosensitive or non-photosensitive be. These duplicate disks may be capable of having an even longer life if they

be subjected to a firing treatment after the protective pressure formation. In particular, "there is a tendency that a duplicate disk having a resin layer having a matrix structure thereon has a substantially improved press life when subjected to a thermal treatment ⁰ C and in the case of a plate with a resin layer with a matrix structure, the thermal treatment should be treated at a temperature above the temperature at which the matrix particles are fused together.

If the resin layer is excessively thick, there arises an undesirable disadvantage that some of the highlights in the image area are lost, thereby deteriorating the image, whereas if the layer is too thin, the intended effect of the resin layer of the present invention is decreased. Considering the Sehutzfähigkeit that Preßlebensdauer that Helief strength, developability, etc. of the printing plate into consideration, the preferable thickness range is suitably at 0 ₉ 1 to 25jam or "u ₉ more preferably 0.5 to 10m or / U «

The printing ink formed on the resin layer in the use of the present invention should be in one Solvent insoluble to remove harase layer its and it is favorable if it adheres firmly to the resin layer. Such a printing color can be selected from those colors whose ink layer on the resin layer has a resistive effect at the time of dissolution to remove the resin layer by a solvent. Therefore, oxidation-polymerization hardening

Printing inks, photo-curing type printing inks, printing inks membrane curing type and the like are used will. If desired, an ink has its Composition strongly adheres to the resin layer, a solubility coefficient similar to that of the resin of the resin layer and is used in combination with the resin, the crystalline nature of which is similar to that of the printing ink. In general, an oily printing ink is used for duplicating or duplicating printing plates, their resin layer removed in an aqueous developer solution shall be.

The formation of an image using an ink on the printing plate with a resin layer thereon according to the invention can be carried out from a template plate or master plate common printing processes, such as off-set printing, letterpress, Typing or typing, screen printing, gravure printing, Ink-jet printing or ink-jet printing.

After printing, the resin layer becomes in the non-image area dissolved for removal by a solvent (hereinafter also referred to as "development"), whereby a printing plate is obtained. Tray printing, although convenient, can be done by curing the printing ink develop the following application by choosing the materials take place; For example, an oily off-set printing ink, such as of the oxidation polymerization hardening type, is used as the printing ink, of the photo-setting type or the thermosetting type used to print on a with alkali-soluble resin coated aluminum plate, which is then in an uncured state in a Bath trough is developed with an alkaline aqueous

Solution is filled, whereby one obtains a printing plate. After development has ended, the printing plate thus obtained can can be used for a printing process to perform printing. In general, the method is the use of an oily printing ink and water or an alkaline-aqueous solution as a developer for the production of printing plates is most suitable.

As a solvent for application "in the dissolution and for Removal of the resin layer, if suitable " only the non-image area has to be removed without the "Dissolve the printed layer in the image area, water or various kinds of solvents can be used. e.g., ^ -butyrolactone (jfc-butylolactone), which is at least one of the ingredients glycerin, water and phosphoric acid can be used. the end For safety and health reasons, it is beneficial to use an aqueous solvent such as one inorganic alkali solution that contains a chemical such as sodium silicate, sodium carbonate, sodium hydroxide, Potassium silicate, potassium hydroxide, lithium hydroxide, sodium diphosphate, Sodium triphosphate, ammonium diphosphate, ammonium triphosphate and sodium metasilicate. To the alkali solution, two or more can be added individually or in combination surfactants or solvents are added, such as cyclohexanone, benzyl alcohol, cyclopentanone, Methyl cellosolve, methyl cellosolve acetate, methyl cellosolve acetate, Carbinol or Carbitol, Dioxane, Phenylcellosolve, Ethyl ce Ho solve, Ethylcellosolve acetate. Solvent, which can be used according to the invention are not restricted to these solvents, but rather include i) common ones Solvents which do not dissolve the layer provided with printing inks, but which are suitable for the purpose

Remove the non-image surface resin layer.

In addition, the printing plate material provided on its surface with the resin layer is according to the invention is, characterized in that it has an excellent storability as compared with known printing plate materials that do not have such resin layers

In the following the invention is illustrated by means of examples explained, but are not intended to represent a restriction.

example 1

In a nitrogen gas stream 0.6 mol of styrene, 0.4 mol of methacrylic acid and 0.001 ΜοΓ were added azobisisobutyronitrile to 100 ml of dioxane and the mixture was reacted at a temperature of 65 ⁰ C while 41 hours. The resulting solution was poured into a large amount of water to obtain a precipitated polymer. The polymer was collected by filtration and dried. 5% by weight of crystal violet was added to the polymer and the mixture was dissolved in methyl cellosolve. In addition, a 0.3 mm thick aluminum plate was subjected to electrolytic polishing treatment and further anodic oxidation so as to prepare a printing plate material. On the aluminum plate, the above resin liquid was coated by means of a rotary applicator so that the thickness of the resin layer became about 1 µm or / U. After drying, the resulting printing plate was made with an image from a master plate using a

Off-set sample press printed. In the ink used it was Toyo King "Ultra 70, a product of Toyo Ink Co», Ltd. ·. After drying of the ink, the plate was a Badet winding with 0.5% aqueous sodium metasilicate during 60 seconds at the temperature of 25 ⁰ G, thereby obtaining a printing plate whose non-image areas were removed The printing plate thus obtained was set in a printing press to carry out printing, and excellent copies in image reproduction were easily obtained in numbers up to 150,000.

Example 2

An aluminum plate prepared in the same manner as in Example 1 was coated with m-cresol-formaldehyde novolak resin dissolved in methanol by means of a cation coater so that the resin coating layer was about 2 µm in thickness after drying the resulting printing plate material is printed with an image from a master plate (stencil plate) using an off-set sample press. The printing ink was Fresh Dry, commercial product of Toyo Ink Co α, Ltd "ο After printing, the plate material was irradiated for 3 minutes with a high-pressure mercury vapor lamp of 2 kW and then in a 4% aqueous sodium metasilicate solution bath for 60 seconds at 25 ⁰ O developed, thereby obtaining a printing plate. The printing plate thus obtained was placed in a printing press to perform a printing operation. The plate was found to be excellent in sensitivity, good oleophilic quality, and gave printed copies with excellent reproduction

effortlessly in numbers of 80,000 without damaging the printed image.

Example 3 "-.

An aluminum plate, prepared in the same manner as in Example 1, was coated with a coating liquid containing a p-hydrorxyphenyl-methacrylamide-methyl methacrylate-acrylonitrile-methacrylic acid copolymer (molar ratio: 2: 4: 3: 1) dissolved in methyl cellosolve, a hot at ions coater was used in such a way that the coating layer had a thickness of / vl lim or η. In the same way as in Example 2, a master plate (template plate) was duplicated. The resulting plate was 60 seconds in a 3.5% aqueous et Nätriumm as ilikatlösung at 25 ⁰ C developed to obtain a printing plate, which was placed in a printing device. 180,000 copies were printed. There was no damage to the relief of the printing plate.

Example 4

An aluminum plate was prepared in the same manner as in Example 1 and coated with a dispersion liquid of Gosenol GL-05 (polyvinyl alcohol, commercial product of Nippon Synthetic Industry Co., Ltd.) and Copolene L-4000 (ethylene-vinyl acetate copolymer, commercial product of Asahi) by means of a wire rod Dow Co., Ltd.) in a weight ratio of 3 'x 4 dispersed in water. The coated product was dried with a fan at a temperature of $ 0C. The "coating layer was about 2 jam or yu thick. On the

resulting. Printing plate - became a picture of a Template "or a master using an off-set sample press printed. The printing ink was Diatone AK-SSP, a commercial product of Sakata Shokai Co., Ltd .. This was developed in running water to remove the ight image area, and then was subjected to a thermal treatment for 5 minutes "at 200 ° 0, thereby obtaining a printing plate became. The printing plate thus prepared was placed in a printing press to give satisfactory printed 150,000 copies, with none Damage to the image on the printing plate detected became.

Example 5

An aluminum plate prepared in the same manner as in Example 1 was prepared by means of a wire rod with a liquid dispersion prepared by dispersing for 24 hours using a ball mill a mixture of 5 parts by weight of m-cresol-i-malaldehyde novolak resin with 1 part by weight of copper phthalocyanine in a methylcellosolve solution coated in such a way that the dry thickness of the coating layer was 3 V ^ - or M. On the resulting product, an image was printed from a master or stencil plate using an off-set sample press. The printing ink used was Toyo King Ultra 70, a commercial product of Toyo.Ink Co., Ltd. After the printing ink had dried, the product was developed for 20 seconds in a 4 % aqueous sodium ^{metasilicate solution at 20 °} C., using a printing plate which was placed in a printing press to produce 150,000 prints

Copies. No damage was found after printing of the image of the printing plate.

Example 6

An aluminum plate prepared in the same manner as in Example Λ was mixed with a liquid of 1,2-naphthoquinonediazide sulfonic acid ester of m-cresol-formaldehyde novolak resin in an amount of 20% by weight of that of the resin in Example 2, dissolved in methanol, " coated so that the coating layer had a thickness of about 2 µm or yu. After drying, an image of a master or stencil plate was printed on the resulting duplicate plate by means of an off-set proofing press. It was the printing ink used Fresh Dry, a commercial product of Toyo Ink Co., Ltd. After printing, it was exposed to the light of a high-pressure mercury vapor lamp of 2 kW for 3 minutes and then developed in a 4% aqueous sodium metasilicate solution at 25 ⁰ O for 60 seconds Formation of a processed duplicate plate, which was then placed in a printing press to form 100 hard copies. There was no damage to the image of the D backplate.

Example 7

An aluminum plate, prepared as in Example 1, was spin coater with a liquid of a condensate of A-diazo - ^ '- phenylaminohexafluorophosphate with formaldehyde in an amount of 8% by weight of the resin of Example 3 »dissolved in methyl cellosolve solvent , coated »The thickness of the coating layer was about 1 µm, or yes. After drying

the resulting product was printed with an image of a master or stencil plate using an off-set sample press. The printing ink used at this point was one which had been prepared in such a way that a mixture of 60 parts by weight of aliphatic size oleic acid, 30 parts by weight of trimethylolpropane and 10 parts by weight of phthalic anhydride was in a nitrogen atmosphere for U hours gas stream was reacted at a temperature of 220 ⁰ O, 15 parts by weight of benzene and 10 parts by weight of acrylic acid were added to the reaction product after cooling to 90 ^{0 C for reaction with stirring over 3 hours;} the viscosity of this reaction product was then adjusted to 700 dPa.s (poise) by adding a linseed oil varnish; 3% by weight of benzoin methyl ether and 3% by weight of Michler's ketone were then added. After printing, the duplicate plate was developed in a 3 »5% aqueous solution of sodium metasilicate to remove the image area and, in addition, it was irradiated with the light of a high-pressure queekilver vapor lamp of 2 kV for 3 minutes to obtain a printing plate which was then placed in a printing press to produce a satisfactory 180,000 hard copies. No damage could be found on the image of the printing plate.

Claims (2)

Applicant: Konishiroku Photo Industry Co., Ltd. T 52 No. 26-2 Nishishinjuku 1-chome
Shin; Juku-ku Tokyo / Japan Method of making a printing plate Pat ent claims A process for preparing a printing plate, characterized in that it forms an image of an ink on a .Harzschicht, which is located on a printing plate material and that the resin "layer in the portion in which the image is not formed from the _ink} dissolves with a solvent for the resin. 2. A method of making a printing plate, thereby characterized in that an image is made from a printing ink using a printing stencil (Heisterdruck « plate) forms on a resin layer, which is seen on a printing plate material and that the Resin layer in the portion where the image was not formed from the printing ink with a solvent for the resin dissolves.