EP0620125A1 - Adjuvant d'impression - Google Patents

Adjuvant d'impression Download PDF

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Publication number
EP0620125A1
EP0620125A1 EP93923053A EP93923053A EP0620125A1 EP 0620125 A1 EP0620125 A1 EP 0620125A1 EP 93923053 A EP93923053 A EP 93923053A EP 93923053 A EP93923053 A EP 93923053A EP 0620125 A1 EP0620125 A1 EP 0620125A1
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EP
European Patent Office
Prior art keywords
water
acid
printing plate
soluble
assistant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP93923053A
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German (de)
English (en)
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EP0620125B1 (fr
EP0620125A4 (fr
Inventor
Mitsuo Hattori
Hitoshi Furuta
Taro Takahashi
Hirokazu Maeda
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Fuji Oil Co Ltd
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Fuji Oil Co Ltd
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Filing date
Publication date
Priority claimed from JP05114318A external-priority patent/JP3052663B2/ja
Application filed by Fuji Oil Co Ltd filed Critical Fuji Oil Co Ltd
Priority claimed from US08/265,443 external-priority patent/US5468287A/en
Publication of EP0620125A1 publication Critical patent/EP0620125A1/fr
Publication of EP0620125A4 publication Critical patent/EP0620125A4/fr
Application granted granted Critical
Publication of EP0620125B1 publication Critical patent/EP0620125B1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N3/00—Preparing for use and conserving printing surfaces
    • B41N3/08—Damping; Neutralising or similar differentiation treatments for lithographic printing formes; Gumming or finishing solutions, fountain solutions, correction or deletion fluids, or on-press development

Definitions

  • the present invention relates to a printing assistant. More particularly, it is concerned with a printing assistant useful as a printing plate protective agent, a printing plate cleaner, an image eraser, a sensitization protective agent, a gum remover, dampening water for printing, etc.
  • Lithography is a printing method which effectively utilizes the property of water and oil in that they essentially do not mix.
  • a printing plate for lithography comprises a water-receptive and oil-base-ink-repellent portion and a water-repellent and oil-base-ink-receptive portion, with the former constituting a nonimage area and the latter constituting an image area.
  • assistants for a lithographic printing plate such as printing plate protective agents, printing plate cleaners, image erasers, sensitization protective agents and gum removers, are used in order to protect the nonimage areas.
  • Water-soluble polymers having a film formability have hitherto been used as an indispensable ingredient of the assistant.
  • a plate protective agent is coated (this procedure being usually referred to as "gumming") for the purpose of protecting the nonimage areas.
  • the plate protective agent is used in order to maintain the hydrophilicity of the nonimage areas by taking advantage of the film formability and for other purposes such as correction in image areas, such as retouching or elimination, storage in a period between after plate making and before initiation of printing or storage until reuse, prevention of contamination caused by deposition of fingerprints, fats and oils, dust, etc., during handling at the time of mounting the plate in a printing machine, protection against occurrence of flaws and prevention of contamination by oxidation.
  • the conventional plate protective agent comprises a solution of a water-soluble polymer, such as gum arabic, cellulose gum or a polymer having a carboxyl group in its molecule and optional additives, such as pH adjustors and preservatives.
  • a water-soluble polymer such as gum arabic, cellulose gum or a polymer having a carboxyl group in its molecule
  • optional additives such as pH adjustors and preservatives.
  • the plate protective agent when gum arabic, which is a naturally occurring plant gum substance, is used as the water-soluble polymer, it exhibits an excellent film formability.
  • the surface of the substrate at its portions where the images have been removed should be rendered hydrophilic so that these portions do not receive the ink during printing.
  • useful image erasing techniques which can satisfy the above requirements, are very few.
  • Examples of a useful image erasing technique include a technique where the unnecessary images are physically rubbed out with a stone rod, a technique where the images and the substrate are subjected to etching with a strongly alkaline solution to remove the unnecessary images and a technique where a solution containing an organic solvent capable of dissolving an image and an acidic substance, such as hydrofluoric acid, is used to dissolve unnecessary images and, at the same time, to etch the substrate to impart hydrophilicity to the substrate in its nonimage areas.
  • the former method has drawbacks including the fact that a large area cannot be treated and contamination occurs during printing.
  • the two latter methods have several drawbacks including the fact that necessary images in their fine portions are damaged, harmfulness to human body and skin is high and there occurs a problem of waste water treatment. For this reason, the above techniques are not always satisfactory.
  • gum arabic is used as the water-soluble polymer used in a plate cleaner for protecting nonimage areas, a sensitization protective agent or a gum remover, it exhibits an excellent film formability.
  • dampening water for lithography wets nonimage areas to increase the interfacial chemical difference between the image area and the nonimage area, thereby enhancing the ink repellency of the nonimage area and the ink receptivity of the image area.
  • a water-soluble polymer having a film formability is used as an indispensable ingredient.
  • gum arabic which is a naturally occurring plant gum substance
  • it exhibits an excellent film formability as dampening water for lithography.
  • gum arabic which has hitherto been used as a water-soluble polymer in assistants for lithography, exhibits an excellent suitability for all the assistants.
  • the supply thereof is susceptible to weather in production countries, so that the price fluctuation is large. For this reason, in recent years, naturally occurring gum substances, which can be stably supplied, have become strongly desired in the art.
  • An object of the present invention is to provide a printing assistant which exhibits a stable film formability for a long period of time, is inexpensive and can be stably supplied.
  • the present invention provides an printing assistant comprising a water-soluble hemicellulose as an effective ingredient.
  • the water-soluble hemicellulose is preferably derived from beans, particularly soybeans, among others derived from seed leaves thereof.
  • the average molecular weight of the water-soluble hemicellulose is preferably in the range of from several tens of thousands to several millions, specifically in the range of from 50,000 to one million.
  • the average molecular weight of the water-soluble hemicellulose is a value determined by the limiting viscosity method wherein the viscosity is measured in a 0.1 M NaNO3 solution using a standard Pullulan (manufactured by Showa Denko K.K.) as a standard substance. Uronic acid was measured by the Blumenkrantz method, and neutral sugars were measured by GLC (gas-liquid chromatography) after alditol acetylation.
  • the water-soluble hemicellulose can be produced by extracting the water-soluble hemicellulose from a raw material containing hemicelluloses with water or in some cases, by heat-eluting the hemicellulose therefrom under acidic or alkaline conditions or decomposition-eluting the hemicellulose therefrom with an enzyme.
  • An embodiment of the above-described process for producing the water-soluble hemicellulose will now be described.
  • Husks of oily seeds for example, soybeans, palm, coconut, corn and cottonseeds, usually obtained by removing fats and oils and proteins therefrom, or vegetable matter, such as residues of grains, for example, rice and wheat, usually obtained by removing starch therefrom.
  • soybeans are used as the raw material, bean curd residue (okara) produced as a by-product in the production of a bean curd, a soybean milk or a separated soybean protein may be utilized as the raw material.
  • the above-described raw material is heat-decomposed under acidic or alkaline conditions, preferably in a pH region around the isoelectric point of each protein, preferably at 80 to 130°C, still preferably 100 to 130°C, to fractionate a water-soluble fraction which is then dried as it is or alternatively subjected to, for example, an activated carbon treatment, a resin adsorption treatment or an ethanol precipitation treatment to remove hydrophobic substances or low-molecular substances and dried to provide a water-soluble hemicellulose.
  • water-soluble hemicellulose is used as the water-soluble polymer, which is the raw material for the assistant for a lithographic printing plate and the dampening water for lithography, more stable film formation can be attained as compared with use of gum arabic or modified starch.
  • the assistant for a lithographic printing plate is in an emulsion form, use of the water-soluble hemicellulose can provide products having a better emulsifiability than use of gum arabic or chemically modified starch.
  • the water-soluble hemicellulose as such, can be used as the water-soluble polymer.
  • use thereof in combination with conventional water-soluble polymers can compensate for the drawbacks of the conventional water-soluble polymers.
  • Examples of conventional naturally occurring water-soluble polymers include gum arabic, tragacanth gum, carageenan, xanthan gum, gelatin, casein sodium, guar gum, gum tare, glue plants ( funori ), agar, furcellaran, tamarind seed polysaccharides, gum karaya, hibiscus, pectin, sodium alginate, pullulan, jellan gum, locust bean gum, albumin such as whey and various starches.
  • semi-synthetic water-soluble polymers include carboxymethyl cellulose (CMC), methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), alginic acid propylene glycol ester and chemically modified starches including soluble starches.
  • CMC carboxymethyl cellulose
  • MC methyl cellulose
  • EC ethyl cellulose
  • HEC hydroxyethyl cellulose
  • alginic acid propylene glycol ester alginic acid propylene glycol ester
  • chemically modified starches including soluble starches.
  • Examples of conventional synthetic water-soluble polymers include polyethylene glycol and copolymers thereof, polyvinyl alcohol and copolymers thereof, polyvinyl pyrrolidone, polyacrylamide and copolymers thereof, polyacrylic acid and copolymers thereof, vinyl methyl ether/maleic anhydride copolymer, vinyl acetate/maleic anhydride copolymer and polystyrenesulfonic acid and copolymers thereof.
  • the effect of the water-soluble hemicellulose according to the present invention is further improved by using the water-soluble hemicellulose in combination with at least one member selected from the above-described various water-soluble polymers.
  • the water-soluble hemicellulose can compensate for the drawbacks of the various water-soluble polymers.
  • the amount thereof used is preferably in the range of from 0.1 to 35% by weight, still preferably in the range of from 0.3 to 25% by weight, based on the total weight of the plate protective agent.
  • the plate protective agent is advantageously used in an acidic region, that is, in a pH range of from 3 to 6.
  • an acidic region that is, in a pH range of from 3 to 6.
  • it is suitable to use a mineral acid, an organic acid, an inorganic salt or the like in the protective agent.
  • the mineral acid include sulfuric acid, nitric acid, phosphoric acid and metaphosphoric acid, and acetic acid, citric acid, oxalic acid, malonic acid, p-toluenesulfonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, organic sulfonic acid, ascorbic acid, gluconic acid, hydroxyacetic acid, sulfanilic acid, phytic acid, etc. are useful as the organic acid. Further, alkali metal salts, alkaline earth metal salts and ammonium salt of these mineral acids and organic acids may be favorably used.
  • the mineral acids, organic acids and their salts and the like may be used alone or in a combination of two or more of them.
  • surfactants may be added to the plate protective agent of the present invention for the purpose of improving the surface state of the coating.
  • Examples of the surfactants usable in the present invention include anionic surfactants and nonionic surfactants.
  • the anionic surfactant include salts of aliphatic alcohol sulfates, salts of aliphatic alcohol phosphates, salts of dibasic fatty acid ester sulfonates, salts of fatty acid amide sulfonates, salts of alkylaryl sulfonates and salts of naphthalene sulfonate condensed with formaldehyde
  • examples of the nonionic surfactant include polyethylene glycol alkyl ethers, polyethylene glycol alkyl esters, sorbitan alkyl esters and polyoxypropylene polyoxyethylene ethers.
  • the surfactants may be used in a combination of two or more of them.
  • the amount of the surfactant added is not particularly limited, it is preferably in the range of from 0.01 to 10% by weight based on the plate protective agent.
  • wetting agents may be added according to need.
  • Lower polyhydric alcohols such as glycerin, ethylene glycol and triethylene glycol, may be used as the wetting agent.
  • the amount of the wetting agent added is preferably in the range of from 0.1 to 5% by weight, still preferably in the range of from 0.5 to 3% by weight, based on the plate protective agent.
  • Benzoic acid and derivatives thereof, phenol, formalin and sodium dehydroacetate may be added as the preservative in an amount in the range of from 0.005 to 2% by weight based on the plate protective agent.
  • the plate protective agent of the present invention may be used for various lithographic printing plates.
  • it can be suitably used for lithographic printing plates formed by subjecting a photosensitive lithographic printing plate (PS plate) comprising an aluminum plate as a substrate and, provided thereon, a photosensitive layer to imagewise exposure and then development.
  • PS plate photosensitive lithographic printing plate
  • the content of the water-soluble polymer in the image eraser is preferably in the range of from 0.1 to 5% by weight, still preferably in the range of from 0.5 to 3% by weight.
  • the organic solvent used in the image eraser of the present invention serves to dissolve or swell the photosensitive layer to which the eraser is applied, and examples of the organic solvent include ketones, such as acetone, methyl ethyl ketone, methyl isopropyl ketone, diisobutyl ketone and cyclohexanone, hydrocarbons, such as benzene, toluene and xylene, ethers, such as methyl glycol, ethyl glycol and butyl glycol, esters, such as methyl glycol acetate and ethyl glycol acetate, aromatic alcohols, such as propyl alcohol, butyl alcohol, benzyl alcohol and ethylene glycol, and other organic solvents, such as dimethylformamide and butyrolactone. They may be used alone or in the form of a mixture of two or more of them.
  • ketones such as acetone, methyl ethyl ketone, methyl isopropyl
  • dimethylformamide, cyclohexanone, xylene, ethyl glycol acetate, etc. are preferred.
  • the content of the organic solvent in the image eraser is in the range of from 50 to 90% by weight, still preferably in the range of from 60 to 80% by weight.
  • surfactants usable in the present invention include known nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. Among them, those which can be dissolved or dispersed in the organic solvent used can be selected and used.
  • nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylallyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan alkyl esters and polyoxyethylene/polyoxypropylene copolymers.
  • the surfactants may be used alone or in a combination of two or more of them.
  • the content of the surfactant in the image eraser is suitably in the range of from 3 to 20% by weight, preferably in the range of from 5 to 15% by weight.
  • the image eraser is advantageously used in an acidic region, that is, a pH range of from 3 to 6.
  • an acidic region that is, a pH range of from 3 to 6.
  • it is suitable to use a mineral acid, an organic acid, an inorganic salt or the like in the image eraser.
  • the image eraser of the present invention can be easily prepared by mixing the above various ingredients together.
  • the object in using the image eraser can be easily attained by soaking a brush with the image eraser thus prepared, coating the image eraser in this state on the image in its portion to be erased and then conducting washing with water. Further, recontamination of the erased image portion during printing can also be eliminated.
  • the lithographic printing plate treated with the image eraser of the present invention can be coated with a plate protective agent, that is, subjected to a gumming treatment, to ensure a good storage stability after the treatment.
  • the image eraser of the present invention may be used for both negative-working and positive-working lithographic printing plates. It can be particularly favorably used for the positive-working lithographic printing plate.
  • the amount thereof used is preferably in the range of from 0.001 to 10% by weight, still preferably in the range of from 0.005 to 1% by weight, based on the total weight of the dampening water composition.
  • Mineral acids, organic acids or their salts may be used as the pH buffering substance contained in the dampening water composition of the present invention. These compounds are effective in pH adjustment and pH buffering of the dampening water composition and etching to a suitable extent and prevention of corrosion of the substrate of the lithographic printing plate.
  • the amount of the pH buffering substance added is preferably in the range of from 0.001 to 1% by weight, and the pH buffering substance is preferably used on the acid side of neutrality in a pH range of from 3 to 7.
  • the pH buffering substance may contain an alkali metal oxide, an alkali metal phosphate, an alkali metal carbonate or a silicate and be used the alkali side of neutrality in a pH range of from 7 to 11.
  • the dampening water composition of the present invention may further comprise a solvent, a wetting agent, a preservative, an antifoaming agent, etc.
  • the wetting agent include polyols, glycol ethers, alcohols and surfactants.
  • the polyol and glycol ether include 2-ethyl-1,3-hexanediol, hexyl carbitol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexylene glycol, tetraethylene glycol, 1,5-pentanediol, hexyl cellosolve, glycerin, diglycerin, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol, monomethyl ether, ethylene glycol monopropyl ether, diethylene glycol monopropyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, dipropy
  • Examples of the alcohol include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, n-amyl alcohol and benzyl alcohol.
  • surfactant examples include anionic surfactants, nonionic surfactants and cationic surfactants.
  • anionic surfactant examples include salts of fatty acids, salts of abietic acid, salts of alkanesulfonic acids, salts of hydroxyalkanesulfonic acids, salts of dialkylsulfosuccinic acids, salts of straight-chain alkylbenzenesulfonic acids, salts of branched alkylbenzenesulfonic acids, salts of alkylnaphthalenesulfonic acids, salts of alkylphenoxypolyoxyethylenepropylsulfonic acids, salts of polyoxyethylene alkylsulfophenyl ethers, sodium salt of N-methyl-N-oleyltaurine, disodium salt of N-alkylsulfosuccinic acid monoamides, salts of petroleum sulfonic acids, sulfated castor oil, sulfated beef tallow, salts of sulfates of fatty acid all esters, salts of alkyl sulf
  • nonionic surfactant examples include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ether, polyoxyethylene polyoxypropylene alkyl ether, partial esters of glycerin with fatty acids, partial esters of sorbitan with fatty acids, partial esters of pentaerythritol with fatty acids, esters of propylene glycol with monofatty acids, partial esters of sucrose with fatty acids, partial esters of polyoxyethylene sorbitan with fatty acids, partial esters of polyoxyethylene sorbitol with fatty acids, esters of polyoxyethylene glycol with fatty acids, partial esters of polyglycerin with fatty acids, polyoxyethylenated castor oil, partial esters of polyoxyethylene glycerin with fatty acids, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylenealkylamines, esters of triethanol
  • anionic surfactants examples include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts and polyethylene polyamine derivatives.
  • wetting agents may be used alone or in a combination of two or more of them, and the amount thereof used is preferably in the range of from 0.03 to 5% by weight, still preferably in the range of from 0.05 to 3% by weight, based on the total weight of the dampening water composition.
  • preservative usable in the present invention include phenol and derivatives thereof, imidazole derivatives, formalin, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzotriazole derivatives, amidine guanidine derivatives, quaternary ammonium salts, derivatives of pyridine, quinoline and guanidine, diazine, triazole derivatives, oxazole and oxazine derivatives.
  • the preservative is added in such an amount as to effectively exhibit the effect against bacteria, fungi, yeast, etc., and although the amount thereof used varies depending upon the kinds of microorganisms, such as bacteria, fungi and yeast, it is preferably in the range of from 0.001 to 1% by weight based on the total weight of the dampening water composition used. In this case, it is preferred to use at least two preservatives in combination so that the effect can be attained against various microorganisms, such as bacteria, fungi and yeast.
  • the anti-foaming agent usable in the present invention may be any one so far as it can exhibit the anti-foaming effect.
  • silicone compounds are preferred.
  • the silicone compounds are classified into emulsion type and one-pack type. Both types can exhibit the intended effect in a small amount, and the amount of the anti-foaming agent used is preferably in the range of from 0.001 to 0.3% by weight based on the total weight of the dampening water composition used.
  • chelate compounds may be added to the dampening water composition of the present invention.
  • the purpose of adding the chelate compound is to eliminate a problem that calcium and other ions contained in tap water, well water and other water used for dilution in using the dampening water composition have an adverse effect on printing.
  • any chelate compound may be favorably used so long as it can stably exist in the dampening water composition and is not detrimental to the printing property.
  • the chelate compound include organic phosphonic acids or phosphonoalkanetricarboxylic acids, such as ethylenediaminetetraacetic acid, potassium salt of ethylenediaminetetraacetic acid, sodium salt of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, potassium salt of diethylenetriaminepentaacetic acid, sodium salt of diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, potassium salt of triethylenetetraminehexaacetic acid, sodium salt of triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, potassium salt of hydroxyethylethylenediaminetriacetic acid, sodium salt of hydroxyethylethylenediaminetriacetic acid, nitrilotriace
  • the amount of the chelate compounds added is preferably in the range of from 0.001 to 5% by weight, still preferably in the range of from 0.005 to 1% by weight, based on the total weight of the dampening water composition used.
  • the dampening water composition of the present invention may further comprise various additives, which can stably exist in the dampening water composition and are not detrimental to the printing property, such as various colorants, rust preventives and agents for preventing oxidative staining in nonimage areas.
  • various additives which can stably exist in the dampening water composition and are not detrimental to the printing property, such as various colorants, rust preventives and agents for preventing oxidative staining in nonimage areas.
  • Colorants which can be suitably used in the present invention, include food dyes. Specific examples thereof include yellow dyes, such as C.I. Nos. 19140 and 15985, red dyes, such as C.I. Nos. 16185, 45430, 16255, 45380 and 45100, blue dyes, such as C.I. Nos. 42090 and 73015, and green dyes, such as C.I. No. 42095.
  • yellow dyes such as C.I. Nos. 19140 and 15985
  • red dyes such as C.I. Nos. 16185, 45430, 16255, 45380 and 45100
  • blue dyes such as C.I. Nos. 42090 and 73015
  • green dyes such as C.I. No. 42095.
  • rust preventive examples include benzotriazole, tolyltriazole, benzoimidazole and 2-mercaptobenzoimidazole.
  • the agents for preventing oxidative staining in nonimage areas include zinc nitrate, magnesium nitrate and sodium nitrate.
  • the dampening water composition of the present invention be produced as a concentrated solution and diluted 10- to 1000-fold with tap water, well water or the like prior to use.
  • lithographic printing plate examples include various lithographic printing plates, such as photosensitive lithographic printing plates (PS plates), deep-etch plates, multilayer metallic plates, such as bimetal and trimetal plates, direct drawing masters and lithographic printing plates for electrophotography.
  • PS plates photosensitive lithographic printing plates
  • deep-etch plates deep-etch plates
  • multilayer metallic plates such as bimetal and trimetal plates
  • direct drawing masters and lithographic printing plates for electrophotography.
  • water-soluble hemicellulose was dissolved in 0.5% saline, and reprecipitation was repeated three times in such a manner that the ethanol concentration became 50%, followed by desalting with an ion-exchange resin ("Amberlite IR-120 B" manufactured by Organo Corp.) to provide water-soluble hemicellulose (b).
  • Water-soluble hemicellulose (c) was provided as described above, except that the treatment using an activated carbon column was not effected.
  • the sugar composition of the water-soluble hemicelluloses (a), (b) and (c) was analyzed by the following method.
  • Uronic acid was measured by the Blumenkrantz method, and neutral sugars were measured by the alditol acetate method using GLC.
  • the above-described ingredients were homogeneously mixed together to provide a plate protective agent for a lithographic printing plate.
  • a printing plate protective agent was prepared in quite the same manner as that of Example 1, except that water-soluble soybean hemicellulose (b) was used instead of water-soluble soybean hemicellulose (a).
  • a printing plate protective agent was prepared in quite the same manner as that of Example 1, except that water-soluble soybean hemicellulose (c) was used instead of water-soluble soybean hemicellulose (a).
  • a printing plate protective agent was prepared in quite the same manner as that of Example 1, except that gum arabic was used instead of water-soluble soybean hemicellulose (a).
  • a printing plate protective agent was prepared in quite the same manner as that of Comparative Example 1, except that dextrin was used instead of gum arabic.
  • a photosensitive lithographic printing plate was prepared for the purpose of evaluating the effect of the printing plate protective agents provided in the above Examples and Comparative Examples.
  • a 0.241 mm-thick aluminum plate was immersed in a 7% aqueous solution of sodium tertiary phosphate at 60°C to effect degreasing, washed with water and grained by brushing the aluminum plate with a nylon brush while running a solution of pumice suspended in water. After washing with water, the grained aluminum plate was versed for 30 to 60 sec in a 5% aqueous solution of potassium silicate (SiO2/K2O molar ratio: 2.0) kept at 70°C, thoroughly washed with water and then dried.
  • potassium silicate SiO2/K2O molar ratio: 2.0
  • a sensitizing solution comprising 6.2 parts of 2-hydroxyethyl methacrylate copolymer (as synthesized by the process described in Example 1 of British Patent No. 1505739), 0.4 part of 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate of a condensate of p-diazodiphenylamine with paraformaldehyde 0.1 part of Oil Blue #603 (manufactured by Orient Chemical Industries, Ltd.), 46.7 parts of 2-methoxyethanol, 31.1 parts of methanol and 15.5 parts of ethylene chloride was coated on the above-described aluminum substrate at a weight coverage on a dry basis of 1.8 g/m2 to provide a photosensitive lithographic printing plate.
  • the resultant printing plate was exposed using a halftone negative film and developed with an aqueous developing solution comprising 0.3 part of sodium sulfite, 2.8 parts of benzyl alcohol, 1.9 parts of triethanolamine, 0.5 part of monoethanolamine, 1.0 part of sodium t-butylnaphthalenesulfonate and 93.5 parts of pure water, washed with water and dried.
  • an aqueous developing solution comprising 0.3 part of sodium sulfite, 2.8 parts of benzyl alcohol, 1.9 parts of triethanolamine, 0.5 part of monoethanolamine, 1.0 part of sodium t-butylnaphthalenesulfonate and 93.5 parts of pure water, washed with water and dried.
  • the printing plate was then divided into six separate plates. Among the six plates, five plates were coated with the plate protective agents prepared in the above examples and comparative examples, and excessive protective agents were wiped off with a cloth. The remaining one plate was not coated with any plate protective agent.
  • thermo-hygrostat a temperature of 45°C and a humidity of 85% for 3 days
  • printing was carried out according to the conventional method using a Heiderlerg KOR-D printing machine to determine the number of failed prints necessary to provide a sharp print and to observe staining during printing.
  • the lithographic printing plate protective agents using the water-soluble soybean hemicellulose were excellent in both sensitization in image areas and desensitization in nonimage areas.
  • the lithographic printing plate protective agent using a water-soluble hemicellulose as a water-soluble polymer can be easily applied onto a plate using a sponge, a cotton tampon, an automatic gum coater, etc., is excellent in both sensitization in image areas and desensitization in nonimage areas and can be easily removed even after storage for a long period of time by washing with water or contact with a dampening roller. Further, since the hydrophilicity in the nonimage areas and the lipophilicity in the image areas can be held, there is no possibility that the lithographic printing plate treated with the lithographic printing plate protective agent will cause printing dropout.
  • the solution B was added dropwise and dispersed in the solution A with stirring and then emulsified through a homogenizer (manufactured by GAULIN) to provide a lithographic printing plate cleaner.
  • a homogenizer manufactured by GAULIN
  • a printing plate cleaner was prepared in quite the same manner as that of Example 4, except that water-soluble soybean hemicellulose (c) was used instead of water-soluble soybean hemicellulose (a).
  • a printing plate cleaner was prepared in quite the same manner as that of Example 4, except that gum arabic was used instead of water-soluble soybean hemicellulose (a).
  • a positive-working photosensitive lithographic printing plate was prepared by the method described in Example 1 of Japanese Examined Patent Publication (Kokoku) No. 51-33444.
  • a part of the nonimage areas on the resultant printing plate was damaged by a needle, and oleic acid was rubbed into the damaged portion.
  • Printing was carried out on 100 sheets of a printing medium using the damaged printing plate. As a result, in all the prints, staining was observed on portions of the prints corresponding to the damaged portions of the printing plate.
  • the damaged printing plate at its contaminated site was wiped with each printing plate cleaner, and printing was further carried out on 60,000 sheets of a printing medium to observe whether or not the contaminated site could be cleaned completely.
  • the printing plate cleaners using water-soluble hemicelluloses were excellent in emulsifiability, capability of removing contaminant in a hydrophilic region and capability of forming again the hydrophilic region.
  • An image eraser was prepared in the same manner as that of Example 6, except that water-soluble soybean hemicellulose (b) was used instead of water-soluble soybean hemicellulose (a).
  • An image eraser was prepared in the same manner as that of Example 6, except that water-soluble soybean hemicellulose (c) was used instead of water-soluble soybean hemicellulose (a).
  • An image eraser was prepared in the same manner as that of Example 6, except that gum arabic was used instead of water-soluble soybean hemicellulose (a).
  • a positive-working photosensitive lithographic printing plate was prepared by the method described in Example 1 of Japanese Examined Patent Publication (Kokoku) No. 51-33444.
  • a mixture of a diazo oxide resin with a phenolic resin was coated as a photosensitive layer on a grained and anodized aluminum plate to provide a positive-working photosensitive lithographic printing plate.
  • the printing plate was subjected to imagewise exposure through a halftone positive-working film and then developed with an alkaline developing solution to form an image on the printing plate.
  • a suitable amount of each image eraser was then coated on a part of the image by a hair pencil, and the coating was allowed to stand for 2 min. Thereafter, the eraser was washed away with running water, and the printing plate was dehydrated and gummed.
  • Printing was carried out on 30,000 sheets of a printing medium using the printing plate to observe whether the image portion coated with each image eraser did not receive the printing ink, that is, could successfully erased the unnecessary image completely.
  • the image erasers using water-soluble hemicelluloses were excellent in capability of preventing an image from remaining unremoved by washing and the stability in removal of an image.
  • the image eraser for a lithographic printing plate using a water-soluble hemicellulose as the water-soluble polymer can be easily prepared by simply mixing ingredients together and coating of the image eraser on an image portion to be erased has excellent effects of preventing an image from remaining unremoved by washing and stably erasing the image.
  • a dampening water composition was prepared in the same manner as that of Example 9, except that water-soluble soybean hemicellulose (b) was used instead of water-soluble soybean hemicellulose (a).
  • a dampening water composition was prepared in the same manner as that of Example 9, except that water-soluble soybean hemicellulose (c) was used instead of water-soluble soybean hemicellulose (a).
  • a dampening water composition was prepared in the same manner as that of Example 9, except that gum arabic was used instead of water-soluble soybean hemicellulose (a).
  • a dampening water composition was prepared in the same manner as that of Comparative Example 5, except that dextrin was used instead of gum arabic.
  • a dampening water composition was prepared in the same manner as that of Example 12, except that gum arabic was used instead of water-soluble soybean hemicellulose (a).
  • FPS-2 anodized multigrain type positive-working PS plate manufactured by Fuji Photo Film Co., Ltd.
  • a lithographic printing plate was exposed and developed using a PS automatic developing machine 800E2, a positive developing solution DP-4 (manufactured by Fuji Photo Film Co., Ltd.) (diluted 8-fold with water) and a positive finisher FP (diluted twice with water) (manufactured by Fuji Photo Film Co., Ltd.) and then gummed. It was then mounted on the above-described printing machine, and dampening properties were evaluated in terms of the following items.
  • Printing was carried out on 5000 to 10000 sheets of a printing medium using an ink (Apex G, Kurenai S; manufactured by Dainippon Ink and Chemicals, Inc.), and the operation of the printing machine was ceased to examine and evaluate the degree of bleeding of the ink of the image areas on the nonimage areas.
  • Fresh water was used as dampening water to determine the amount of dampening water necessary to cause no contamination even when printing was carried out on 10000 sheets of a printing medium (necessary minimum amount of water supply). Then, printing was carried out using various types of dampening water in this necessary minimum amount to evaluate the continuos printing stability based on the number of prints which could be successfully obtained without staining of the print.
  • a stock solution can be easily prepared by mixing the ingredients together, and what should be done for use of the dampening water composition is only to dilute the stock solution with tap water or well water. Further, the resultant diluted solution had excellent properties as the dampening water composition, such as prevention of contamination of the metering roll, prevention of bleeding, emulsion stability and continuous printing stability.
  • the protective agent for lithographic printing plate prepared by using a water-soluble hemicellulose as an assistant for a lithographic printing plate can be easily applied onto the plate by using a sponge, a cotton tampon, an automatic gum coater, etc., is excellent in both sensitization in image areas and desensitization in nonimage areas and can be easily removed by washing with water or contact with a dampening roller even after storage for a long period of time. Further, since the hydrophilicity in the nonimage areas and the lipophilicity in the image areas can be held, there is no possibility that the lithographic printing plate treated with the lithographic printing plate protective agent gives rise to printing dropout.
  • a stock solution can be easily prepared by simply mixing the ingredients together, and coating of the eraser on an image portion to be erased has excellent effects of preventing occurrence of any residue that remains unremoved after washing and stably erasing the image.
  • the dampening water composition for lithographic printing prepared by using a water-soluble hemicellulose exhibits excellent effects, such as prevention of contamination of the metering roll, prevention of bleeding, emulsion stability and continuous printing stability.
  • the printing assistant comprising a water-soluble hemicellulose as an effective ingredient is superior to the conventional water-soluble polymers in properties such as film formability, long-term storage stability, emulsifiability and desensitization in nonimage areas. Therefore, the present invention is very useful from the viewpoint of industry.

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  • Printing Plates And Materials Therefor (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)

Abstract

Adjuvant d'impression renfermant comme constituant actif de l'hémicellulose hydrosoluble. Cet adjuvant présente d'excellentes caractéristiques filmogènes, une longue durée de conservation, d'excellentes caractéristiques d'émulsification, d'excellentes caractéristiques de désensibilisation pour les parties sans image, ainsi qu'une excellente stabilité d'émulsification et une stabilité continue comme composition aqueuse humectante pour l'impression.
EP93923053A 1992-11-02 1993-10-22 Procede d' impression lithographique et utilisation de hemicellulose soluble dans l'eau comme adjuvant d'impression pour des plaques d'impression lithographiques Expired - Lifetime EP0620125B1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
JP31782992 1992-11-02
JP31782892 1992-11-02
JP317829/92 1992-11-02
JP317828/92 1992-11-02
JP114318/93 1993-05-17
JP05114318A JP3052663B2 (ja) 1992-11-02 1993-05-17 印刷用助剤
PCT/JP1993/001535 WO1994009993A1 (fr) 1992-11-02 1993-10-22 Adjuvant d'impression
US08/265,443 US5468287A (en) 1992-11-02 1994-06-24 Water color

Publications (3)

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EP0620125A1 true EP0620125A1 (fr) 1994-10-19
EP0620125A4 EP0620125A4 (fr) 1995-03-29
EP0620125B1 EP0620125B1 (fr) 1999-03-17

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Cited By (2)

* Cited by examiner, † Cited by third party
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EP0770501A3 (fr) * 1995-10-19 1997-12-03 Tecnicas Especiales de Oxigenacion, S.L. Perfectionnements introduits aux systèmes pour mouiller les plaques lithographiques et mécanisme à cet effet
EP2002987A1 (fr) * 2007-06-13 2008-12-17 Agfa Graphics N.V. Procédé pour traiter une plaque d'impression lithographique

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3121966B2 (ja) * 1993-08-12 2001-01-09 富士写真フイルム株式会社 平版印刷版用版面保護剤
ES2344668T3 (es) 2007-11-30 2010-09-02 Agfa Graphics N.V. Metodo para tratar una plancha de impresion litografica.

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US4095525A (en) * 1975-10-31 1978-06-20 Sumitomo Chemical Company, Limited Protective coating material for lithographic printing plate
US4186250A (en) * 1975-04-07 1980-01-29 The Dow Chemical Company Method of desensitizing image-bearing lithographic plates
JPS56112982A (en) * 1980-02-12 1981-09-05 Kiyoshi Fukui Size composition and processing method
JPH05263367A (ja) * 1992-03-11 1993-10-12 Fuji Oil Co Ltd 繊維加工用糊剤
WO1993025302A1 (fr) * 1992-06-16 1993-12-23 Fuji Oil Co., Ltd Emulsifiant, composition emulsifiante et composition sous forme de poudre

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JPS62275782A (ja) * 1986-02-05 1987-11-30 Fuji Photo Film Co Ltd 平版印刷版用版面保護剤
JPH04235096A (ja) * 1990-12-19 1992-08-24 Fuji Photo Film Co Ltd 平版印刷用湿し水組成物及び平版印刷方法

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US4186250A (en) * 1975-04-07 1980-01-29 The Dow Chemical Company Method of desensitizing image-bearing lithographic plates
US4095525A (en) * 1975-10-31 1978-06-20 Sumitomo Chemical Company, Limited Protective coating material for lithographic printing plate
JPS56112982A (en) * 1980-02-12 1981-09-05 Kiyoshi Fukui Size composition and processing method
JPH05263367A (ja) * 1992-03-11 1993-10-12 Fuji Oil Co Ltd 繊維加工用糊剤
WO1993025302A1 (fr) * 1992-06-16 1993-12-23 Fuji Oil Co., Ltd Emulsifiant, composition emulsifiante et composition sous forme de poudre
EP0598920A1 (fr) * 1992-06-16 1994-06-01 Fuji Oil Co., Ltd. Emulsifiant, composition emulsifiante et composition sous forme de poudre

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0770501A3 (fr) * 1995-10-19 1997-12-03 Tecnicas Especiales de Oxigenacion, S.L. Perfectionnements introduits aux systèmes pour mouiller les plaques lithographiques et mécanisme à cet effet
EP2002987A1 (fr) * 2007-06-13 2008-12-17 Agfa Graphics N.V. Procédé pour traiter une plaque d'impression lithographique
WO2008152028A1 (fr) * 2007-06-13 2008-12-18 Agfa Graphics Nv Procédé de traitement d'une plaque d'impression lithographique
US8445179B2 (en) 2007-06-13 2013-05-21 Agfa Graphics Nv Method for treating a lithographic printing plate

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WO1994009993A1 (fr) 1994-05-11
EP0620125A4 (fr) 1995-03-29

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