CA2034965A1 - Lithographic plate finisher - Google Patents
Lithographic plate finisherInfo
- Publication number
- CA2034965A1 CA2034965A1 CA 2034965 CA2034965A CA2034965A1 CA 2034965 A1 CA2034965 A1 CA 2034965A1 CA 2034965 CA2034965 CA 2034965 CA 2034965 A CA2034965 A CA 2034965A CA 2034965 A1 CA2034965 A1 CA 2034965A1
- Authority
- CA
- Canada
- Prior art keywords
- plate
- starch
- acid
- gum
- salts
- 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.)
- Abandoned
Links
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
Landscapes
- Printing Plates And Materials Therefor (AREA)
- Photosensitive Polymer And Photoresist Processing (AREA)
Abstract
Abstract of the Disclosure A non-emulsion type plate finisher which comprises a solvent whose solubility in water at 20°C is not more than 5 %
by weight. The plate finisher is excellent in the desensitizing ability and does not deteriorate the ink receptivity of image areas. The lithographic printing plate to which the plate finisher is applied has good ink receptivity from the beginning of the printing operation. The plate finisher is excellent in stability over time and can be prepared easily with an inexpensive equipment.
by weight. The plate finisher is excellent in the desensitizing ability and does not deteriorate the ink receptivity of image areas. The lithographic printing plate to which the plate finisher is applied has good ink receptivity from the beginning of the printing operation. The plate finisher is excellent in stability over time and can be prepared easily with an inexpensive equipment.
Description
Z03496S `
SPECIFICATION
: TITLE OF THE INVENTION `-Lithographic Plate Finisher BACKGROUND OF THE INVENTION
The present invention relates to a lithographic plate finisher.
Upon manufacturing a lithographic printing plate, a gumming up step is performed as the final process. In the gumming up step, a protecting agent, i.e., so-called desensitizing gum is applied onto the surface of the printing plate. This is applied to the plate for the purposes of preventing adhesion of contaminants on the plate after the plate is manufactured and till the plate is set on a printing press to thereby prevent occurrence of background contamination on printed matters and for preventing the formation of defects on the plate surface during storing the plates in the heaped up state or upon hitting them against a foreign substance. The most important purpose of the gumming up step is to prevent the lowering of the hydrophilic properties of non-image areas due to oxidization encountered when the plate surface is directly exposed to air and to enhance the hydrophilic properties thereof. For these reasons, the gumming up is a step indispensable for the plate making process.
As a gumming solution, there has been used, for a long ;~034965 time, a composition comprising an aqueous solution of gum arabic having a concentration ranging from about 15 to 30% by : wei~ht to which additives such as surfactants, pH-adjusting~
agents and preservatives are optionally added.
S However, the desensitizing ability of gum arabic is so strong that the ink receptivity of image areas is often lowered.
Therefore, it is sometimes observed that many unacceptale printed matters are formed till those having satisfactory ink concentration are surely obtained during printing operations.
There has been proposed an emulsion gum solution comprising an oil phase containing a lipophilic surfactant, such as an organic solvent soluble lipophilic surfactant, dissolved in a petroleum ~raction and a water phase containing a water soluble organic high molecular compound dissolved therein. In such emulsion gum solution, gùm arabic serves as not only a desensitizing agent but aiso a protective colloid to stabilize the emulsion.
However, gum arabic is a natural substance which is produced only in limited regions in the world and its amount of harvest is greatly influenced by various factors such as the climate at the regions. Thus the stable supply thereof is not always expected.
~nder such circumstances, many attempts have been directed to the use of a variety of water-soluble polymeric compounds as desensitizing gum lithographic plate finishers instead of gum arabic.
X0~496S
For instance, Japanese Patent Un-examined Publication (hereunder referred to as "J.P. KOKAI") No. Sho 54-97102 (B.P.
- 2010298) discloses dextrin, sterabic, arabogalactan, alginic~_ acid salts, polyacrylic acids, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, methyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose and salts of carboxyalkyl celluloses. Moreover, Japanese Patent Publication for Opposition Purpose (hereunder referred to as "J.P. KOKOKU") No.
Sho 54-41921 discloses pullulan and pullulan derivatives; J.P.
KOKAI No. Sho 58-197091 discloses polyvinyl pyrrolidone; and J.P.
KOKAI No. Sho 56-133193 (U~S.P. 4,349,391) discloses polyvinyl alcohols. J.P.KOKAI No. Sho 59-57242 discloses modified starch derivatives which include roasted starch such as British gum, enzyme-modified dextrin such as enzyme dextrin and Schardinger dextrin, acid-treated starch such as solubilized starch, oxidized starch such as dialdehyde starch, gelatinized starch such as modified or non-modified gelatinized starch, esterified starch such as phosphoric acid starch, fatty acid starch, sulfuric acid starch, nitric acid starch, xanthogenic acid starch and carbamic acid starch, etherified starch such as carboxyalkylated starch, hydroxyalkylated starch, sulfoalkylated starch, cyanoethylated starch, allylated starch, benzylated starch, carbamylethylated starch and dialkylamino starch, crosslinked starch such as methylol crosslinked starch, hydroxyalkyl crosslinked starch, phosphoric acid crosslinked starch and dicarboxylic acid crosslinked starch, and starch ~034965 graft copolymer such as starch polyacrylamide copolymer, starch polyacrylic acid copolymer, starch polyvinyl acetate copolymer, starch polyacrylnitrile copolymer, cationic starch polyacrylate~
copolymer, cationic starch polyvinyl compound copolymer, starch styrene maleic acid copolymer and starch polyethylene oxide copolymer.
However, all the plate finishers using water soluble organic polymeric compounds instead of gum arabic are inferior in the ability to desensitize non-image areas to that of gum arabic and therefore, if they are used as emulsion type gum solutions, the oil phase components often contaminate non-image areas.
Further, the water-soluble organic polymeric compounds are inferior in the property of protective colloid to gum arabic and therefore, emulsion type gum solutions using the polymeric compounds undergo phase separation into oil and aqueous phases in a few days.
Moreover, an expensive machine such as a homogenizer and labors are required to prepare an emulsion tupe gum solution.
To make up for these disadvatages, a non-emulsion type gum solution has been known. However, as explained earlier, the non-emulsion type gum solution using a large amount of gum arabic has disadvantages in that it is inferior in ink receptivity in image areas and that gum arabic is not stably supplied. On the other hand, a non-emulsion type gum solution containing a water-soluble organic polymeric compound instead of 203't~i5 gum arabic is sufficient in the ability of preventing contamination in non-image areas because it does not contain a lipophilic component, but it is insufficient in ink receptivity~
in image areas so that many unacceptable printed matters are produced at the beginnig of printing operation.
S~MMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a lithographic plate finisher (hereunder referred to as "plate finisher") having good ability of desensitizing non-image areas but not reducing ink receptivity of image areas.
Another object of the present invention is to provide a .
plate finisher which is stable against phase separation even when the amount of gum arabic used is small.
A furthe~ object o~ the present invention is to provide a plate finisher which can easily be prepared with an inexpensive machine.
The foregoing objects can be quite effectively attained by a non-emulsion type plate finisher for lithographic printing plates which comprises a solvent whose solubi]ity in water at 20 C is not more than 5 % by weight.
DETAILED EXPLANATION OF THE INVENTION
The present invention will be explained in detail.
SOLV~NTS
The plate finisher of the present invention is characterized in that it comprises a solvent whose solubility in water at 20 C is not more than 5 % by weight. The addition " 203496S`
of such solvent improves ink receptivity of image areas.
Examples of such solvent include benzyl alcohol, ethylene glycol dibutyl ether, ethylene glycol benzyl ether, ethylene~
glycol monophenyl ether, hexyl glycol, hexyl diglycol, propyl propylene diglycol, methyl phenyl carbitol, diethylene glycol dibutyl ether, n-amyl alcohol, metyl amyl alcohol, isophorone, methyl cyclohexanone and acetophenone. Among them, benzyl alcohol is most preferred because it is highly stable and inexpensive but does not give out strong odor.
In the invention, the solvent may be used alone or in combination. The amount of the solvent used is preferably 0.1 to 10 % and more preferably 0.5 to 5 % by weight based on the total weight of the plate finisher. If it is less than 0.1 ~ by weight, ink receptivity of image areas is reduced. On the other hand, if it exceeds 10 % by weight, the plate surface becomes sticky and the drying property is deteriorated. Solvents whose solubility in water is more than 5 % by weight have no or insufficient effect on the prevention of lowering of ink receptivity of image areas.
WATER-SOLUBLE RESI~S
The plate finisher of the present invention may contain a variety of water-soluble resins.
Examples of such resins include natural high molecular compounds such as starches derived from sweet potato, potato, tapioca, wheat, corn and waxy corn; those derived from sea weeds such as carrageenan, laminaran, sea weed mannan, funori (a .
. X034965 glue plant), Irish moss, agar and sodium alginate; mucilage derived from plants such as tororo-aoi mucin, mannan, quince : seed mucin, pectin, tragacanth gum, karaya gum, xanthine gum,_ guar bean gum, locust bean gum, gum arabic, carob gum and benzoiun gum; mucilage derived from microorganisms such as homopolysaccharides (e.g., dextran, glucan and levan) and heteropolysaccharides (e.g., succinoglucan and xanthane gum);
proteins such as glue, gelatin, casein and collagen;
semisynthetic sompounds such as propylene glycol alginate and cellulose derivatives such as viscose, methyl cellulose, ethyl cellulose, methyl ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and hydroxypropyl methyl cellulose phthalate;
processed starches such as roasted dextrin (e.g., white dextrin, yellow dextrin and British gum), enzyme-modified dextrin such as enzyme dextrin and Schardinger dextrin, acid-treated starch such as solubilized starch, oxidized starch such as dialdehyde starch, gelatinized starch such as modified or non-modified gelatinized starch, esterified starch such as phosphoric acid starch, fatty acid starch, sulfuric acid starch, nitric acid starch, xanthogenic acid starch, carbamic acid starch and succinic acid starch, etherified starch such as carboxyalkylated starch, hydroxyalkylated starch, sulfoalkylated starch, cyanoethylated starch, allylated starch, benzylated starch, carbamylethylated starch and dialkylamino starch, crosslinked starch such as methylol crosslinked starch, ~. 20349~5 hydroxyalkyl crosslinked starch, phosphoric acid crosslinked starch and dicarboxylic acid crosslinked starch, and starch graft copolymer such as starch polyacrylamide copolymer, starch~
polyacrylic acid copolymer, starch polyvinyl acetate copolymer, starch polyacrylnitrile copolymer, cationic starch polyacrylate copolymer, cationic starch polyvinyl compound copolymer, starch styrene maleic acid copolymer and starch polyethylene oxide copolymer; and synthetic compounds such as polyvinyl alcohol, modified polyvinyl alcohol such as partial acetal of polyvinyl alcohol, allyl modified polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether and polyvinyl isobutyl ether, poly(meth)acrylic acid derivatives such as sodium polyacrylate, partially saponified polyacrylate, partially saponified product of acrylate copolymer, salt of polymetha~y~te and polyacrylamide, polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl pyrrolidone-vinyl acetate copolymer, carboxy vinylpolymer, styrene-maleic acid copolymer and styrene-crotonic acid copolymer.
These water-soluble resins may be used in the plate finisher of the present invention alone or in combination in an amount of, preferably, 5 to 40 ~, more preferably 10 to 30 % by weight based on the total weight of the plate finisher.
In the present invention, it is possible to significantly lower the amount of gum arabic to be used in the plate finisher.
Although gum arabic may not be used at all in the finisher, it is preferable to use gum arabic in an amount of 1 to 20 ~ by Z034~65 weight based on the total weight of the water-soluble resin used in the finisher to give sufficient desensitizing ability to non-image areas.
~ ADJ~STING AGENTS
S In general, the plate finisher is preferably used in the acid region, i.e., at pH ranging from 2 to 6. The p~ value is generally adjusted by adding a mineral acid, an organic acid, an inorganic salt, an alkali agent or the like to the plate finisher. The amount thereof generally ranges from 0.01 to 3 % by weight.
Useful examples of the foregoing mineral acids are nitric acid, sulfuric acid and phosphoric acid-and those of the organic acids are citric acid, acetic acid, oxalic acid, malonic acid, p-toluenesulfonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, phytic acid, benzoic acid, butyric acid, maleic acid, picolinic acid and organophosphonic acids .
Useful examples of the foregoing inorganic salts are water soluble alkali metal salts and ammonium salts of nitric acid, phosphoric acid, sulfuric acid, molybdenic acid, acetic acid, polyphosphoric acid and boric acid, such as sodium nitrate, potassium nitrate, ammonium nitrate, monosodium phosphate, disodium phosphate, monopotassium phosphate, dipotassium phosphate, monoammonium phosphate, diammonium phosphate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium molybdate, potassium molybdate, ammonium molybdate, sodium acetate, potassium acetate, ammonium acetate, sodium tripolyphosphate, ~03~965 sodium hexametaphosphate, sodium pyrophosphate, soium borate and ammonium borate and those of the foregoing alkali agents are ; alkali metal hydroxides such as sodium hydroxide, potassium~-hydroxide and lithium hydroxide, and amines such as ammonia, S monoethanol amine, diethanol amine and triethanol amine.
The foregoing mineral acids, organic acids, inorganic salts or alkali agents may be used alone or in combination.
SURFACTANTS
A surfactant can be added to the plate finisher of the present invention to improve the surface conditions or the like of the resulting coated film and to stably solubilize the solvent whose solubility in water at 20 C is not more than 5 % by weight. Examples of the surfactants usable herein include anionic, nonionic, amphoteric and cationic surfactants.
Examples of such anionic surfactants include fatty acid salts, alkylbenzene sulfonic acid salts, straight chain alkylbenzene sulfonic acid salts, alkyl sulfonic acid salts, a -olefin sulfonic acid salts, alkyl phosphoric acid ester salts, dialkyl sulfo succinic acid ester salts, polyoxyethylene alkyl ether sulfonic acid salts, polyoxyethylene alkyl ether phophoric acid salts, alkylnaphthalene sulfonic acid salts, N-lauroyl sarcosine salts, sulfonic acid salts of condensates of naphthalene and formaldehyde, and diphenylether disulfonic acid salts.
Examples of the nonionic surfactants are polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, `` Z034~65`
polyoxyethylene-polyoxypropylene brock copolymers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene : glycerin fatty acid esters, polyethylene glycol fatty acid~
esters, polyoxyethylene fatty acid amines, fatty acid monoglycerides, sorbitan fatty acid esters, pentaerythritol fatty acid esters, sucrose fatty acid esters and amine oxides.
Examples of the amphoteric surfactants are alkylcarboxy betaines, alkylamino carboxylic acids and alkylimidazolines.
Examples of the cationic surfactants are tetraalkyl ammonium salts, trialkyl benzyl ammonium salts and alkyl imidazolinium salts. In addition, there may be mentioned fluorine atom containing surfactants and silicon atom containing surfactants.
Among them, the anionic and/or nonionic surfactants are more effective, The surfactants may be used alone or in combination. The amount thereof used is not limited to a specific range, but preferably it ranges from 0.01 to 10~ by weight on the basis of the total weight of the plate finisher.
WETTING AGENTS, PRESERVATIVES AND OTHER ADDITIVES
In addition to the foregoing components, the plate finisher may further comprise a lower alcohol such as glycerin, ethylene glycol and triethylene glycol as a wetting agent. The amount of the wetting agent preferably ranges from 0.1 to 5.0 %
by weight, more preferably 0.5 to 3.0 ~ by weight based on the total weight of the plate finisher. Moreover, the plate ~. X03~965`
finisher may comprise other additives such as preservatives.
Examples thereof are benzoic acid and derivatives thereof, - phenol, formalin, sodium dehydroacetate and 3-isothiazolones~
These compounds may be used in an amount ranging from 0.005 to 2.0 % by weight of the plate finisher. Further, the plate finisher may contain other additives which are used in conventional plate finishers, for example, anti-foaming agents, chelating agents and coloring agents.
METHOD OF THE PREPARATION OF THE PLATE FINISHER
The plate finisher of the present invention can be prepared by dissolving with agitation the solvent, a water soluble resin, a surfactant, a pH adjusting agent, a wetting agent and a preservative in water or if necessary in hot water.
Since the plate finisher of the present invention is a non-emulsion type gum solution, it is unnecessary to prepare a water phase and an oil phase and subsequently to emulsify the mixture with a homogenizer unlike an emulsion type gum solution. Thus, the plate finisher of the present invention can be prepared easily with an inexpensive equipment.
PRESENSITIZED PLATE
The plate finisher of this invention may be applied to various kinds of lithographic printing plates, in particular the plate finisher can suitably be applied to those obtained by imagewise exposing a presensitized plate (called "PS plate") comprising an aluminum substrate provided thereon with a light-sensitive layer and then developing the same. Examples of '~03~965 preferred such PS plates include those comprising an aluminum substrate provided thereon with a light-sensitive layer composed : of a mixture of a diazo resin (a salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and shellac as disclosed in British Patent No. 1,350,521; negative working PS
plates such as those comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a mixture of a diazo resin and a polymer mainly composed of repeating units derived from hydroxyethyl methyacrylate or hydroxyethyl acrylate as disclosed in British Patent Nos. 1,460,978 and 1,505,739; and positive working PS plates such as those comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a mixture of o-quinonediazide light sensitive substance and a novolak type phenol resin as disclosed in J.P. KOKAI No. Sho 50-125806. Preferred examples of such PS plates further include PS plates comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a photocross-linkable photopolymer specifically described in U.S. Patent No. 3,860,426; PS plates comprising an aluminum plate provided thereon with a light-sensitive layer composed of a photopolymerizable photopolymer composition as disclosed in U.S. Patent Nos. 4,072,528 and 4,072,527; and PS
plates comprising an aluminum plate provided thereon with a light-sensitive layer composed of a mixture of an azide and a water-soluble polymer as disclosed in British Patent Nos. 1,235, 281 and 1,495,861.
~ 20;:~9~5`
APPLICATION OF THE PLATE FINISHER
A method for using the plate finisher of the present : invention will hereunder be explained specifically with~
reference to an example in which a PS plate is used.
First of all, a PS plate is imagewise exposed to light and then developed to give a lithographic printing plate.
A developer usable in the foregoing development is an alkaline solution whose principal solvent is water. The developer optionally comprises additives such as organic solvents, anionic surfactants and inorganic salts in addition to an alkaline ayent.
Specific examples of the alkaline agents include inorganic alkaline agents such as sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium tertiaxy phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate and ammonium carbonatei and organic alkaline agents such as mono-, di- or tri-ethanolamine and propanolamine. The amount thereof used in the developer preferably ranges from 0.05 to 4 % by weight and more preferably 0.1 to 2 % by weight Examples of useful organic solvents are alcohols such as n-propyl alcohol and benzyl alcohol; and glycol ethers such as phenyl cellosolve. The organic solvents are added to the developer preferably in an amount ranging from 0.5 to 15 ~ by weight and more preferably 1 to 5 ~ by weight.
~xamples of anionic surfactants include alkylsulfuric acid 2034965 `
ester salts such as sodium laurylsulfate; alkylarylsulfonic acid salts such as sodium dodecylbenzenesulfonate; sulfonic acid salts of dibasic fatty acid esters such as sodium di-(2--ethylhexyl)sulfosuccinate; alkylnaphthalenesulfonic acid salts such as sodium n-butylnaphthalene-sulfonate; and polyoxyethylene alkyl(phenol) ether sulfates and in particular alkylnaphthalenesulfonic acid salts such as n-b utylnaphthalenesulfonic acid salt are suitably used. The amount of the anionic surfactants in the developer preferably ranges from 0.1 to 5 % by weight and more preferably 0.5 to 1.5 % by weight.
Examples of inorganic salts are water-soluble alkali metal or alkaline earth metal salts of inorganic acids such as phosphoric acid, silicic acid, carbonic acid and sulfurous acid and, particularly preferred are alkali and alkaline earth metal salts of sulfurous acid. The amount of these inorganic salts in the developer in general ranges from 0.05 to 5 % by weight and preferably 0.1 to 1 % by weight.
It is also advantageous that the developer further comprises other additives such as antifoaming agents and wetting agents, if necessary.
The imagewise exposed PS plate can be developed with the foregoing developer in various known manners. Specific examples of methods for developing the imagewise exposed PS plate include a method comprising dipping the PS plate in a developer;
a method comprising spraying a developer on the light-sensitive ~ Z03~9~5 `
layer of the PS plate through a plurality of nozzles; a method comprising rubbing the light-sensitive layer of the PS plate : with a sponge containing a developer; and a method comprising-applying a developer to the surface of the light-sensitive S layer of the PS plate with a roller.
The resulting lithographic printing plate thus developed is washed with water, the water is squeezed from the surface of the PS plate, then a proper amount of the plate finisher of the present invention is poured onto the plate surface. Then, the plate surface is rubbed with a sponge so that the plate finisher is uniformly distributed throughout the plate surface.
As a result, non-image areas of the plate surface can be protected and hence the lithographic printing plate can stably stored.
The plate finisher can be applied to the plate surface in various manner, for example, by applying the plate finisher to the resulting lithographic printing plate after the development and water washing by use of an automatic gumming-up machine;
supplying it to the printing plate immediately after the development without water washing; or applying it to the printing plate after water washing with a small amount of water or after rinsing with a rinse solution containing a surfactant by use of an automatic gumming-up machine.
The lithographic printing plate is in general washed with water, prior to the printing operation to remove the gum on the plate surface (so-called degumming step) and then printing is ~ 2034~36S`
performed in a conventional manner. However, the plate finisher of the present invention makes it possible to directly perform : the printing operation without carrying out such a degumming~
step. Moreover, the plate finisher of the present invention provides acceptable clear printed matters immediately after the initiation of the printing operation without providing a great number of unacceptable printed matters as usually observed when conventional gumming solution is used. Non-image areas treated by the plate finisher of the present invention are kept highly hydrophilic. Thus, the plate finisher of the present invention can provide good printed matters free of background contamination.
EXAM~LES
The present invention will hereunder be explained in more detail with reference to the following non-limitative working Examples and the effect practically achieved by the present invention will also be discussd in detail in comparison with Comparative Examples.
In the following Examples and Comparative Examples, the term "%" means "% by weight" unless otherwise specified.
Example 1 (a) Lithographic printing plate An aluminum plate having a thickness of 0.24 mm was degreased by immersing it in 7~ aqueous solution of tertiary sodium phosphate maintained at 60~C , washed with water and rubbed with a nylon brush with pouring an aqueous suspension of pumice stone to carry out graining. After washing with water, it was immersed in 5% aqueous solution of potassium silicate : (molar ratio of SiO2/K2O = 2.0) maintained at 70 C for 30 to 60 seconds. After sufficiently washing with water, the aluminum plate was dried.
The aluminum substrate thus treated was coated with a solution of a light-sensitive composition (hereunder referred to as "light-sensitive solution") comprising 2.0 parts by weight of 2-hydroxyethyl methacrylate copolymer (synthesized according to the method disclosed in Example 1 of British Patent No.
1,505,739), 0.12 part by weight of 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid salt of a condensate of p-diazodiphenylamine and paraformaldehyde, 0.03 part by weight of Oil Blue ~603 (available from ORIENT CHEMICA~ INDUSTRIES CO., LTD,), 15 parts by weight of 2-methoxyethanol, 10 parts by weight of methanol and 5.0 parts by weight of ethylene chloride to obtain a PS plate having a coated amount of the light-sensitive layer of 1.8 g/m2 (weighed after drying).
(b) Plate finisher Gum solution I
Component Amount (part by weight) Pure water 750 Gum arabic 20 Enzyme modified potato starch 200 (viscosity (20%): 10 cps at 20C ) l 8 - , .' "' '' '' ' :
20349~5 Enzyme modified corn starch 40 (viscosity (20%): 5 cps at 20 C ) .. Phosphated waxy starch 20 (viscosity (20~): 40 cps at 20C ) (phosphorus bonded per unit: 1.0) Sodium dilauryl sulfosuccinate 10 Ammonium phosphate 3 Phosphoric acid (85 %) . 4 EDTA-4Na 3 Ethylene glycol 20 Benzyl alcohol 25 Sodium dehydroacetate 0.5 Emulsion type silicon atom containing 0.2 antifoaming agent Aftér the starches were dissolved in hot water at 80C and cooled, the other components were added and dissolved with stirring to prepare a plate finisher.
Gum solution II
The same as Gum solution I except that bénzyl alcohol was not added, Gum solution III
Aqueous solution A
Component Amount (part by weight) Pure water 750 Gum arabic 150 , , Enzyme modified potato starch 130 (viscosity (20%): 10 cps at 20C ) Ammonium phosphate 3 Phosphoric acid (85 %) 4 EDTA-4Na 3 Ethylene glycol 20 Sodium dehydroacetate 0.5 ~mulsion type silicon atom containing 0.2 antifoaming agent Solution B
Sodium dilauryl sulfosuccinate 10 Polyoxyethylene nonyl phenyl ether (HLB = 7.8) 3 Rosin ester (manufactured by ARAKAWA CHEMICAL INC.) 5 Dioctyl sebacate 15 In the same manher as in the preparation of Gum solution I, Solution A was prepared. Solution B was gradually added to Solution A with vigorous agitation to obtain an emulsion which was further emulsified with a homogenizer to prepare a plate finisher.
Gum solution IV
The same as Gum solution III except that Gum solution I
was substituted for Solution A.
(c) Test The PS plate prepared in step (a) was exposed to light through a negative transparency having halftone dot image. The exposed plate was processed in an automatic processor (Model 600 . ' , , .
~. ' 20349~.5 EII manufactured by FUJI PHOTO FILM CO., LTD. ) having a developing zone provided with an aqueous developer comprising 3.
0 parts by weight of sodium sulfite, 30.0 parts by weight of~
benzyl alcohol, 20.0 parts by weight of triethanolamine, 5.0 parts by weight of monoethanolamine, 10.0 parts by weight of sodium t-butylnaphthalenesulfonate and 1000 parts by weight of pure water, to develop the exposed plates, and a finishing zone provided with one part by volume of Gum solution I, II, III or IV prepared in step (b) and one part by volume of tap water, to apply each of the plate finishers to the developed plates immediately after the development without washing with water.
Lithographic printing plates were thus prepared.
These printing plates were previously allowed to stand for 3 days in a thermo-humidistat at a temperature of 45 C and a relative humidity (RH) of 85% or for 10 days at a room temperature. Each of the plates was set on a printing press Heidelberg SOR-M and printing operation was conducted without removing the gum in an usual manner using dampening water containing 10 % isopropyl alcohol. The number of spoiled printed matters before acceptable clear printed matters weré obtained, background contamination and stability of the gum solutions were determined. The stability of the gum solutions was evaluated by storing the solutions under ambient conditions and observing the phase separation of the soluticns. The results are shown in Table 1.
Table 1 Z~349~i5 Example Compara~ive Examp e :. _ Gum solution II III IV
The number of spoiled sheets (45 C. 85%, 3 days) 15 > 100 20 9 (10 days,room temp) 12 ~ 5 8 sackground A A A B
contamination l l Stability of stable stable separat- separat-gum solution ed in 1 ed in a year few days A: No or little background contamination B: Background contamination (non-image areas) Comparative Example b used a conventional emulsion type gum solution III wherein a large amount of gum arabic was used.
Comparative Example c used Gum solution IV wherein the amount of gum arabic was reduced and a large amount of a conventional water-soluble resin was used. Comparing with Comparative Example b, Comparative Example c was small in the number of spoiled printed mztters but produced contamination in non-image areas during printing and was so unstable that the solution was separated into a water phase and an oil phase in a few days.
Comparative Example a wherein the oil phase was removed was low in background contamination during printing and high in solution stability but produced many spoiled printed matters.
In contrast, Example 1 of the present invention wherein benzyl alcohol was added was smaller in the number of spoiled printed matters than the conventional emulsion type gum solution Z03~965 (Comparative Example b) and was low in background contamination during printing and high in solution stability. Further, the - gum solution of Example 1 was prepared more easily using more~
inexpensive equipment than the emulsion type gum solutions of Comparative Examples b and c.
Example 2 (d) Lithographic printing plate A light-sensitive solution was prepared by dissolving, in 40 parts by weight of methyl cellosolve, 1 part by weight of naphthoquinone-1,2-diazide-5-sulfonic acid ester of polyhydroxyphenyl obtained by polycondensing acetone and pyrogallol as disclosed in J.P. KOKOKU No. Sho 43-28403 and 2 parts by weight of novolak type cresol-formaldenyde resin.
A grained aluminum plate having a thickness of 0.2 mm was sufficiently washed and then dried. The foregoing light-sensitive solution was applied to the surface of the aluminum plate with a whirler and then dried to thus obtain a positive working PS plate having a light-sensitive layer in a.n amount of about 0.2 g/m2.
(e) Test The PS plate prepared in step (d) was exposed to light through a positive transparency having halftone dot iamage, developed with 3% aqueous solution of sodium sil.icate, washed with water and dried.
The exposed plate was processed in an automatic processor (Model 800 EB manufactured by PUJI PHOTO PILM CO., LTD.) having , . . .
;~0349~5 a developing zone provided with 3 ~ aqueous sodium silicate solution, to develop the exposed plates, and a finishing zone - provided with one part by volume of Gum solution I, II, III or~
IV prepared in step (b) and one part by volume of tap water, to apply each of the plate finishers to the developed plates immediately after the development without washing with water.
Lithographic printing plates were thus prepared.
These printing plates were previously allowed to stand for 3 days in a thermo-humidistat at a temperature of 45 C and a relative humidity (RH) of 85% or for 10 days at a room temperature~ Each of the plates was set on a printing press Heidelberg SOR-M and printing operation was conducted without removing the gum in an usual manner using dampening water containing 10 % isopropyl alcohol. The results are shown in Table 2.
03~965 Table 2 . ~xampleCompara1 .ive ~ amp]e Gum solution II III IV
The number of spoiled sheets (45 C, 85~, 3 days) 13 90 18 8 (lO days,room temp) lO 50 12 8 Background A A A B .
contamination Stability of stablestable separat- separat-gum solution ed in l ed in a year few days A: No or little background contamination B: Background contamination (non-image areas) Table 2 shows that Example 2 gave good results like Example l.
Example 3, 4 and 5 The same procedures as in Examples l and 2 were repeated except that benzyl alcohol in Gum solution I was replaced by ethylene glycol monophenyl ether, propylpropylene diglycol or n-amyl alcohol. The results are shown in Table 3.
20~9~i5 Table 3 _ xample Solvent S-l S-2 S-3 Amount (parts by weight) 25 35 20 Same procedures as spoiled sheets in Example 1 45 C , 85%, 3 days 20 22 30 room temp., 10 days 18 20 25 Background A A A
contamination Same procedures as spoiled sheets in Example 2 45 C , ~5%, 3 days 18 20 23 room temp., 10 days 15 15 18 Background A A A
contamination _ Stability good good good S-l: Ethylene glycol monophenyl ether S-2: Propylpropylene diglycol S-3: n-Amyl alcohol In all Examples, the number of spoiled printed matters was much smaller than Comparative Examples a and d and no background contamination was observed during printing.
The plate finisher of the present invention is excellent in the desensitizing ability and does not deteriorate the ink receptivity of image areas. Therefore, the lithographic printing plate to which the plate finisher of this invention is applied has good ink receptivity from the beginning of the printing operation. Moreover, the plate finisher of the invention is excellent in stability over time and can be prepared easily with an inexpensive equipment.
SPECIFICATION
: TITLE OF THE INVENTION `-Lithographic Plate Finisher BACKGROUND OF THE INVENTION
The present invention relates to a lithographic plate finisher.
Upon manufacturing a lithographic printing plate, a gumming up step is performed as the final process. In the gumming up step, a protecting agent, i.e., so-called desensitizing gum is applied onto the surface of the printing plate. This is applied to the plate for the purposes of preventing adhesion of contaminants on the plate after the plate is manufactured and till the plate is set on a printing press to thereby prevent occurrence of background contamination on printed matters and for preventing the formation of defects on the plate surface during storing the plates in the heaped up state or upon hitting them against a foreign substance. The most important purpose of the gumming up step is to prevent the lowering of the hydrophilic properties of non-image areas due to oxidization encountered when the plate surface is directly exposed to air and to enhance the hydrophilic properties thereof. For these reasons, the gumming up is a step indispensable for the plate making process.
As a gumming solution, there has been used, for a long ;~034965 time, a composition comprising an aqueous solution of gum arabic having a concentration ranging from about 15 to 30% by : wei~ht to which additives such as surfactants, pH-adjusting~
agents and preservatives are optionally added.
S However, the desensitizing ability of gum arabic is so strong that the ink receptivity of image areas is often lowered.
Therefore, it is sometimes observed that many unacceptale printed matters are formed till those having satisfactory ink concentration are surely obtained during printing operations.
There has been proposed an emulsion gum solution comprising an oil phase containing a lipophilic surfactant, such as an organic solvent soluble lipophilic surfactant, dissolved in a petroleum ~raction and a water phase containing a water soluble organic high molecular compound dissolved therein. In such emulsion gum solution, gùm arabic serves as not only a desensitizing agent but aiso a protective colloid to stabilize the emulsion.
However, gum arabic is a natural substance which is produced only in limited regions in the world and its amount of harvest is greatly influenced by various factors such as the climate at the regions. Thus the stable supply thereof is not always expected.
~nder such circumstances, many attempts have been directed to the use of a variety of water-soluble polymeric compounds as desensitizing gum lithographic plate finishers instead of gum arabic.
X0~496S
For instance, Japanese Patent Un-examined Publication (hereunder referred to as "J.P. KOKAI") No. Sho 54-97102 (B.P.
- 2010298) discloses dextrin, sterabic, arabogalactan, alginic~_ acid salts, polyacrylic acids, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, methyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose and salts of carboxyalkyl celluloses. Moreover, Japanese Patent Publication for Opposition Purpose (hereunder referred to as "J.P. KOKOKU") No.
Sho 54-41921 discloses pullulan and pullulan derivatives; J.P.
KOKAI No. Sho 58-197091 discloses polyvinyl pyrrolidone; and J.P.
KOKAI No. Sho 56-133193 (U~S.P. 4,349,391) discloses polyvinyl alcohols. J.P.KOKAI No. Sho 59-57242 discloses modified starch derivatives which include roasted starch such as British gum, enzyme-modified dextrin such as enzyme dextrin and Schardinger dextrin, acid-treated starch such as solubilized starch, oxidized starch such as dialdehyde starch, gelatinized starch such as modified or non-modified gelatinized starch, esterified starch such as phosphoric acid starch, fatty acid starch, sulfuric acid starch, nitric acid starch, xanthogenic acid starch and carbamic acid starch, etherified starch such as carboxyalkylated starch, hydroxyalkylated starch, sulfoalkylated starch, cyanoethylated starch, allylated starch, benzylated starch, carbamylethylated starch and dialkylamino starch, crosslinked starch such as methylol crosslinked starch, hydroxyalkyl crosslinked starch, phosphoric acid crosslinked starch and dicarboxylic acid crosslinked starch, and starch ~034965 graft copolymer such as starch polyacrylamide copolymer, starch polyacrylic acid copolymer, starch polyvinyl acetate copolymer, starch polyacrylnitrile copolymer, cationic starch polyacrylate~
copolymer, cationic starch polyvinyl compound copolymer, starch styrene maleic acid copolymer and starch polyethylene oxide copolymer.
However, all the plate finishers using water soluble organic polymeric compounds instead of gum arabic are inferior in the ability to desensitize non-image areas to that of gum arabic and therefore, if they are used as emulsion type gum solutions, the oil phase components often contaminate non-image areas.
Further, the water-soluble organic polymeric compounds are inferior in the property of protective colloid to gum arabic and therefore, emulsion type gum solutions using the polymeric compounds undergo phase separation into oil and aqueous phases in a few days.
Moreover, an expensive machine such as a homogenizer and labors are required to prepare an emulsion tupe gum solution.
To make up for these disadvatages, a non-emulsion type gum solution has been known. However, as explained earlier, the non-emulsion type gum solution using a large amount of gum arabic has disadvantages in that it is inferior in ink receptivity in image areas and that gum arabic is not stably supplied. On the other hand, a non-emulsion type gum solution containing a water-soluble organic polymeric compound instead of 203't~i5 gum arabic is sufficient in the ability of preventing contamination in non-image areas because it does not contain a lipophilic component, but it is insufficient in ink receptivity~
in image areas so that many unacceptable printed matters are produced at the beginnig of printing operation.
S~MMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a lithographic plate finisher (hereunder referred to as "plate finisher") having good ability of desensitizing non-image areas but not reducing ink receptivity of image areas.
Another object of the present invention is to provide a .
plate finisher which is stable against phase separation even when the amount of gum arabic used is small.
A furthe~ object o~ the present invention is to provide a plate finisher which can easily be prepared with an inexpensive machine.
The foregoing objects can be quite effectively attained by a non-emulsion type plate finisher for lithographic printing plates which comprises a solvent whose solubi]ity in water at 20 C is not more than 5 % by weight.
DETAILED EXPLANATION OF THE INVENTION
The present invention will be explained in detail.
SOLV~NTS
The plate finisher of the present invention is characterized in that it comprises a solvent whose solubility in water at 20 C is not more than 5 % by weight. The addition " 203496S`
of such solvent improves ink receptivity of image areas.
Examples of such solvent include benzyl alcohol, ethylene glycol dibutyl ether, ethylene glycol benzyl ether, ethylene~
glycol monophenyl ether, hexyl glycol, hexyl diglycol, propyl propylene diglycol, methyl phenyl carbitol, diethylene glycol dibutyl ether, n-amyl alcohol, metyl amyl alcohol, isophorone, methyl cyclohexanone and acetophenone. Among them, benzyl alcohol is most preferred because it is highly stable and inexpensive but does not give out strong odor.
In the invention, the solvent may be used alone or in combination. The amount of the solvent used is preferably 0.1 to 10 % and more preferably 0.5 to 5 % by weight based on the total weight of the plate finisher. If it is less than 0.1 ~ by weight, ink receptivity of image areas is reduced. On the other hand, if it exceeds 10 % by weight, the plate surface becomes sticky and the drying property is deteriorated. Solvents whose solubility in water is more than 5 % by weight have no or insufficient effect on the prevention of lowering of ink receptivity of image areas.
WATER-SOLUBLE RESI~S
The plate finisher of the present invention may contain a variety of water-soluble resins.
Examples of such resins include natural high molecular compounds such as starches derived from sweet potato, potato, tapioca, wheat, corn and waxy corn; those derived from sea weeds such as carrageenan, laminaran, sea weed mannan, funori (a .
. X034965 glue plant), Irish moss, agar and sodium alginate; mucilage derived from plants such as tororo-aoi mucin, mannan, quince : seed mucin, pectin, tragacanth gum, karaya gum, xanthine gum,_ guar bean gum, locust bean gum, gum arabic, carob gum and benzoiun gum; mucilage derived from microorganisms such as homopolysaccharides (e.g., dextran, glucan and levan) and heteropolysaccharides (e.g., succinoglucan and xanthane gum);
proteins such as glue, gelatin, casein and collagen;
semisynthetic sompounds such as propylene glycol alginate and cellulose derivatives such as viscose, methyl cellulose, ethyl cellulose, methyl ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and hydroxypropyl methyl cellulose phthalate;
processed starches such as roasted dextrin (e.g., white dextrin, yellow dextrin and British gum), enzyme-modified dextrin such as enzyme dextrin and Schardinger dextrin, acid-treated starch such as solubilized starch, oxidized starch such as dialdehyde starch, gelatinized starch such as modified or non-modified gelatinized starch, esterified starch such as phosphoric acid starch, fatty acid starch, sulfuric acid starch, nitric acid starch, xanthogenic acid starch, carbamic acid starch and succinic acid starch, etherified starch such as carboxyalkylated starch, hydroxyalkylated starch, sulfoalkylated starch, cyanoethylated starch, allylated starch, benzylated starch, carbamylethylated starch and dialkylamino starch, crosslinked starch such as methylol crosslinked starch, ~. 20349~5 hydroxyalkyl crosslinked starch, phosphoric acid crosslinked starch and dicarboxylic acid crosslinked starch, and starch graft copolymer such as starch polyacrylamide copolymer, starch~
polyacrylic acid copolymer, starch polyvinyl acetate copolymer, starch polyacrylnitrile copolymer, cationic starch polyacrylate copolymer, cationic starch polyvinyl compound copolymer, starch styrene maleic acid copolymer and starch polyethylene oxide copolymer; and synthetic compounds such as polyvinyl alcohol, modified polyvinyl alcohol such as partial acetal of polyvinyl alcohol, allyl modified polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether and polyvinyl isobutyl ether, poly(meth)acrylic acid derivatives such as sodium polyacrylate, partially saponified polyacrylate, partially saponified product of acrylate copolymer, salt of polymetha~y~te and polyacrylamide, polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl pyrrolidone-vinyl acetate copolymer, carboxy vinylpolymer, styrene-maleic acid copolymer and styrene-crotonic acid copolymer.
These water-soluble resins may be used in the plate finisher of the present invention alone or in combination in an amount of, preferably, 5 to 40 ~, more preferably 10 to 30 % by weight based on the total weight of the plate finisher.
In the present invention, it is possible to significantly lower the amount of gum arabic to be used in the plate finisher.
Although gum arabic may not be used at all in the finisher, it is preferable to use gum arabic in an amount of 1 to 20 ~ by Z034~65 weight based on the total weight of the water-soluble resin used in the finisher to give sufficient desensitizing ability to non-image areas.
~ ADJ~STING AGENTS
S In general, the plate finisher is preferably used in the acid region, i.e., at pH ranging from 2 to 6. The p~ value is generally adjusted by adding a mineral acid, an organic acid, an inorganic salt, an alkali agent or the like to the plate finisher. The amount thereof generally ranges from 0.01 to 3 % by weight.
Useful examples of the foregoing mineral acids are nitric acid, sulfuric acid and phosphoric acid-and those of the organic acids are citric acid, acetic acid, oxalic acid, malonic acid, p-toluenesulfonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, phytic acid, benzoic acid, butyric acid, maleic acid, picolinic acid and organophosphonic acids .
Useful examples of the foregoing inorganic salts are water soluble alkali metal salts and ammonium salts of nitric acid, phosphoric acid, sulfuric acid, molybdenic acid, acetic acid, polyphosphoric acid and boric acid, such as sodium nitrate, potassium nitrate, ammonium nitrate, monosodium phosphate, disodium phosphate, monopotassium phosphate, dipotassium phosphate, monoammonium phosphate, diammonium phosphate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium molybdate, potassium molybdate, ammonium molybdate, sodium acetate, potassium acetate, ammonium acetate, sodium tripolyphosphate, ~03~965 sodium hexametaphosphate, sodium pyrophosphate, soium borate and ammonium borate and those of the foregoing alkali agents are ; alkali metal hydroxides such as sodium hydroxide, potassium~-hydroxide and lithium hydroxide, and amines such as ammonia, S monoethanol amine, diethanol amine and triethanol amine.
The foregoing mineral acids, organic acids, inorganic salts or alkali agents may be used alone or in combination.
SURFACTANTS
A surfactant can be added to the plate finisher of the present invention to improve the surface conditions or the like of the resulting coated film and to stably solubilize the solvent whose solubility in water at 20 C is not more than 5 % by weight. Examples of the surfactants usable herein include anionic, nonionic, amphoteric and cationic surfactants.
Examples of such anionic surfactants include fatty acid salts, alkylbenzene sulfonic acid salts, straight chain alkylbenzene sulfonic acid salts, alkyl sulfonic acid salts, a -olefin sulfonic acid salts, alkyl phosphoric acid ester salts, dialkyl sulfo succinic acid ester salts, polyoxyethylene alkyl ether sulfonic acid salts, polyoxyethylene alkyl ether phophoric acid salts, alkylnaphthalene sulfonic acid salts, N-lauroyl sarcosine salts, sulfonic acid salts of condensates of naphthalene and formaldehyde, and diphenylether disulfonic acid salts.
Examples of the nonionic surfactants are polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, `` Z034~65`
polyoxyethylene-polyoxypropylene brock copolymers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene : glycerin fatty acid esters, polyethylene glycol fatty acid~
esters, polyoxyethylene fatty acid amines, fatty acid monoglycerides, sorbitan fatty acid esters, pentaerythritol fatty acid esters, sucrose fatty acid esters and amine oxides.
Examples of the amphoteric surfactants are alkylcarboxy betaines, alkylamino carboxylic acids and alkylimidazolines.
Examples of the cationic surfactants are tetraalkyl ammonium salts, trialkyl benzyl ammonium salts and alkyl imidazolinium salts. In addition, there may be mentioned fluorine atom containing surfactants and silicon atom containing surfactants.
Among them, the anionic and/or nonionic surfactants are more effective, The surfactants may be used alone or in combination. The amount thereof used is not limited to a specific range, but preferably it ranges from 0.01 to 10~ by weight on the basis of the total weight of the plate finisher.
WETTING AGENTS, PRESERVATIVES AND OTHER ADDITIVES
In addition to the foregoing components, the plate finisher may further comprise a lower alcohol such as glycerin, ethylene glycol and triethylene glycol as a wetting agent. The amount of the wetting agent preferably ranges from 0.1 to 5.0 %
by weight, more preferably 0.5 to 3.0 ~ by weight based on the total weight of the plate finisher. Moreover, the plate ~. X03~965`
finisher may comprise other additives such as preservatives.
Examples thereof are benzoic acid and derivatives thereof, - phenol, formalin, sodium dehydroacetate and 3-isothiazolones~
These compounds may be used in an amount ranging from 0.005 to 2.0 % by weight of the plate finisher. Further, the plate finisher may contain other additives which are used in conventional plate finishers, for example, anti-foaming agents, chelating agents and coloring agents.
METHOD OF THE PREPARATION OF THE PLATE FINISHER
The plate finisher of the present invention can be prepared by dissolving with agitation the solvent, a water soluble resin, a surfactant, a pH adjusting agent, a wetting agent and a preservative in water or if necessary in hot water.
Since the plate finisher of the present invention is a non-emulsion type gum solution, it is unnecessary to prepare a water phase and an oil phase and subsequently to emulsify the mixture with a homogenizer unlike an emulsion type gum solution. Thus, the plate finisher of the present invention can be prepared easily with an inexpensive equipment.
PRESENSITIZED PLATE
The plate finisher of this invention may be applied to various kinds of lithographic printing plates, in particular the plate finisher can suitably be applied to those obtained by imagewise exposing a presensitized plate (called "PS plate") comprising an aluminum substrate provided thereon with a light-sensitive layer and then developing the same. Examples of '~03~965 preferred such PS plates include those comprising an aluminum substrate provided thereon with a light-sensitive layer composed : of a mixture of a diazo resin (a salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and shellac as disclosed in British Patent No. 1,350,521; negative working PS
plates such as those comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a mixture of a diazo resin and a polymer mainly composed of repeating units derived from hydroxyethyl methyacrylate or hydroxyethyl acrylate as disclosed in British Patent Nos. 1,460,978 and 1,505,739; and positive working PS plates such as those comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a mixture of o-quinonediazide light sensitive substance and a novolak type phenol resin as disclosed in J.P. KOKAI No. Sho 50-125806. Preferred examples of such PS plates further include PS plates comprising an aluminum substrate provided thereon with a light-sensitive layer composed of a photocross-linkable photopolymer specifically described in U.S. Patent No. 3,860,426; PS plates comprising an aluminum plate provided thereon with a light-sensitive layer composed of a photopolymerizable photopolymer composition as disclosed in U.S. Patent Nos. 4,072,528 and 4,072,527; and PS
plates comprising an aluminum plate provided thereon with a light-sensitive layer composed of a mixture of an azide and a water-soluble polymer as disclosed in British Patent Nos. 1,235, 281 and 1,495,861.
~ 20;:~9~5`
APPLICATION OF THE PLATE FINISHER
A method for using the plate finisher of the present : invention will hereunder be explained specifically with~
reference to an example in which a PS plate is used.
First of all, a PS plate is imagewise exposed to light and then developed to give a lithographic printing plate.
A developer usable in the foregoing development is an alkaline solution whose principal solvent is water. The developer optionally comprises additives such as organic solvents, anionic surfactants and inorganic salts in addition to an alkaline ayent.
Specific examples of the alkaline agents include inorganic alkaline agents such as sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium tertiaxy phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate and ammonium carbonatei and organic alkaline agents such as mono-, di- or tri-ethanolamine and propanolamine. The amount thereof used in the developer preferably ranges from 0.05 to 4 % by weight and more preferably 0.1 to 2 % by weight Examples of useful organic solvents are alcohols such as n-propyl alcohol and benzyl alcohol; and glycol ethers such as phenyl cellosolve. The organic solvents are added to the developer preferably in an amount ranging from 0.5 to 15 ~ by weight and more preferably 1 to 5 ~ by weight.
~xamples of anionic surfactants include alkylsulfuric acid 2034965 `
ester salts such as sodium laurylsulfate; alkylarylsulfonic acid salts such as sodium dodecylbenzenesulfonate; sulfonic acid salts of dibasic fatty acid esters such as sodium di-(2--ethylhexyl)sulfosuccinate; alkylnaphthalenesulfonic acid salts such as sodium n-butylnaphthalene-sulfonate; and polyoxyethylene alkyl(phenol) ether sulfates and in particular alkylnaphthalenesulfonic acid salts such as n-b utylnaphthalenesulfonic acid salt are suitably used. The amount of the anionic surfactants in the developer preferably ranges from 0.1 to 5 % by weight and more preferably 0.5 to 1.5 % by weight.
Examples of inorganic salts are water-soluble alkali metal or alkaline earth metal salts of inorganic acids such as phosphoric acid, silicic acid, carbonic acid and sulfurous acid and, particularly preferred are alkali and alkaline earth metal salts of sulfurous acid. The amount of these inorganic salts in the developer in general ranges from 0.05 to 5 % by weight and preferably 0.1 to 1 % by weight.
It is also advantageous that the developer further comprises other additives such as antifoaming agents and wetting agents, if necessary.
The imagewise exposed PS plate can be developed with the foregoing developer in various known manners. Specific examples of methods for developing the imagewise exposed PS plate include a method comprising dipping the PS plate in a developer;
a method comprising spraying a developer on the light-sensitive ~ Z03~9~5 `
layer of the PS plate through a plurality of nozzles; a method comprising rubbing the light-sensitive layer of the PS plate : with a sponge containing a developer; and a method comprising-applying a developer to the surface of the light-sensitive S layer of the PS plate with a roller.
The resulting lithographic printing plate thus developed is washed with water, the water is squeezed from the surface of the PS plate, then a proper amount of the plate finisher of the present invention is poured onto the plate surface. Then, the plate surface is rubbed with a sponge so that the plate finisher is uniformly distributed throughout the plate surface.
As a result, non-image areas of the plate surface can be protected and hence the lithographic printing plate can stably stored.
The plate finisher can be applied to the plate surface in various manner, for example, by applying the plate finisher to the resulting lithographic printing plate after the development and water washing by use of an automatic gumming-up machine;
supplying it to the printing plate immediately after the development without water washing; or applying it to the printing plate after water washing with a small amount of water or after rinsing with a rinse solution containing a surfactant by use of an automatic gumming-up machine.
The lithographic printing plate is in general washed with water, prior to the printing operation to remove the gum on the plate surface (so-called degumming step) and then printing is ~ 2034~36S`
performed in a conventional manner. However, the plate finisher of the present invention makes it possible to directly perform : the printing operation without carrying out such a degumming~
step. Moreover, the plate finisher of the present invention provides acceptable clear printed matters immediately after the initiation of the printing operation without providing a great number of unacceptable printed matters as usually observed when conventional gumming solution is used. Non-image areas treated by the plate finisher of the present invention are kept highly hydrophilic. Thus, the plate finisher of the present invention can provide good printed matters free of background contamination.
EXAM~LES
The present invention will hereunder be explained in more detail with reference to the following non-limitative working Examples and the effect practically achieved by the present invention will also be discussd in detail in comparison with Comparative Examples.
In the following Examples and Comparative Examples, the term "%" means "% by weight" unless otherwise specified.
Example 1 (a) Lithographic printing plate An aluminum plate having a thickness of 0.24 mm was degreased by immersing it in 7~ aqueous solution of tertiary sodium phosphate maintained at 60~C , washed with water and rubbed with a nylon brush with pouring an aqueous suspension of pumice stone to carry out graining. After washing with water, it was immersed in 5% aqueous solution of potassium silicate : (molar ratio of SiO2/K2O = 2.0) maintained at 70 C for 30 to 60 seconds. After sufficiently washing with water, the aluminum plate was dried.
The aluminum substrate thus treated was coated with a solution of a light-sensitive composition (hereunder referred to as "light-sensitive solution") comprising 2.0 parts by weight of 2-hydroxyethyl methacrylate copolymer (synthesized according to the method disclosed in Example 1 of British Patent No.
1,505,739), 0.12 part by weight of 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid salt of a condensate of p-diazodiphenylamine and paraformaldehyde, 0.03 part by weight of Oil Blue ~603 (available from ORIENT CHEMICA~ INDUSTRIES CO., LTD,), 15 parts by weight of 2-methoxyethanol, 10 parts by weight of methanol and 5.0 parts by weight of ethylene chloride to obtain a PS plate having a coated amount of the light-sensitive layer of 1.8 g/m2 (weighed after drying).
(b) Plate finisher Gum solution I
Component Amount (part by weight) Pure water 750 Gum arabic 20 Enzyme modified potato starch 200 (viscosity (20%): 10 cps at 20C ) l 8 - , .' "' '' '' ' :
20349~5 Enzyme modified corn starch 40 (viscosity (20%): 5 cps at 20 C ) .. Phosphated waxy starch 20 (viscosity (20~): 40 cps at 20C ) (phosphorus bonded per unit: 1.0) Sodium dilauryl sulfosuccinate 10 Ammonium phosphate 3 Phosphoric acid (85 %) . 4 EDTA-4Na 3 Ethylene glycol 20 Benzyl alcohol 25 Sodium dehydroacetate 0.5 Emulsion type silicon atom containing 0.2 antifoaming agent Aftér the starches were dissolved in hot water at 80C and cooled, the other components were added and dissolved with stirring to prepare a plate finisher.
Gum solution II
The same as Gum solution I except that bénzyl alcohol was not added, Gum solution III
Aqueous solution A
Component Amount (part by weight) Pure water 750 Gum arabic 150 , , Enzyme modified potato starch 130 (viscosity (20%): 10 cps at 20C ) Ammonium phosphate 3 Phosphoric acid (85 %) 4 EDTA-4Na 3 Ethylene glycol 20 Sodium dehydroacetate 0.5 ~mulsion type silicon atom containing 0.2 antifoaming agent Solution B
Sodium dilauryl sulfosuccinate 10 Polyoxyethylene nonyl phenyl ether (HLB = 7.8) 3 Rosin ester (manufactured by ARAKAWA CHEMICAL INC.) 5 Dioctyl sebacate 15 In the same manher as in the preparation of Gum solution I, Solution A was prepared. Solution B was gradually added to Solution A with vigorous agitation to obtain an emulsion which was further emulsified with a homogenizer to prepare a plate finisher.
Gum solution IV
The same as Gum solution III except that Gum solution I
was substituted for Solution A.
(c) Test The PS plate prepared in step (a) was exposed to light through a negative transparency having halftone dot image. The exposed plate was processed in an automatic processor (Model 600 . ' , , .
~. ' 20349~.5 EII manufactured by FUJI PHOTO FILM CO., LTD. ) having a developing zone provided with an aqueous developer comprising 3.
0 parts by weight of sodium sulfite, 30.0 parts by weight of~
benzyl alcohol, 20.0 parts by weight of triethanolamine, 5.0 parts by weight of monoethanolamine, 10.0 parts by weight of sodium t-butylnaphthalenesulfonate and 1000 parts by weight of pure water, to develop the exposed plates, and a finishing zone provided with one part by volume of Gum solution I, II, III or IV prepared in step (b) and one part by volume of tap water, to apply each of the plate finishers to the developed plates immediately after the development without washing with water.
Lithographic printing plates were thus prepared.
These printing plates were previously allowed to stand for 3 days in a thermo-humidistat at a temperature of 45 C and a relative humidity (RH) of 85% or for 10 days at a room temperature. Each of the plates was set on a printing press Heidelberg SOR-M and printing operation was conducted without removing the gum in an usual manner using dampening water containing 10 % isopropyl alcohol. The number of spoiled printed matters before acceptable clear printed matters weré obtained, background contamination and stability of the gum solutions were determined. The stability of the gum solutions was evaluated by storing the solutions under ambient conditions and observing the phase separation of the soluticns. The results are shown in Table 1.
Table 1 Z~349~i5 Example Compara~ive Examp e :. _ Gum solution II III IV
The number of spoiled sheets (45 C. 85%, 3 days) 15 > 100 20 9 (10 days,room temp) 12 ~ 5 8 sackground A A A B
contamination l l Stability of stable stable separat- separat-gum solution ed in 1 ed in a year few days A: No or little background contamination B: Background contamination (non-image areas) Comparative Example b used a conventional emulsion type gum solution III wherein a large amount of gum arabic was used.
Comparative Example c used Gum solution IV wherein the amount of gum arabic was reduced and a large amount of a conventional water-soluble resin was used. Comparing with Comparative Example b, Comparative Example c was small in the number of spoiled printed mztters but produced contamination in non-image areas during printing and was so unstable that the solution was separated into a water phase and an oil phase in a few days.
Comparative Example a wherein the oil phase was removed was low in background contamination during printing and high in solution stability but produced many spoiled printed matters.
In contrast, Example 1 of the present invention wherein benzyl alcohol was added was smaller in the number of spoiled printed matters than the conventional emulsion type gum solution Z03~965 (Comparative Example b) and was low in background contamination during printing and high in solution stability. Further, the - gum solution of Example 1 was prepared more easily using more~
inexpensive equipment than the emulsion type gum solutions of Comparative Examples b and c.
Example 2 (d) Lithographic printing plate A light-sensitive solution was prepared by dissolving, in 40 parts by weight of methyl cellosolve, 1 part by weight of naphthoquinone-1,2-diazide-5-sulfonic acid ester of polyhydroxyphenyl obtained by polycondensing acetone and pyrogallol as disclosed in J.P. KOKOKU No. Sho 43-28403 and 2 parts by weight of novolak type cresol-formaldenyde resin.
A grained aluminum plate having a thickness of 0.2 mm was sufficiently washed and then dried. The foregoing light-sensitive solution was applied to the surface of the aluminum plate with a whirler and then dried to thus obtain a positive working PS plate having a light-sensitive layer in a.n amount of about 0.2 g/m2.
(e) Test The PS plate prepared in step (d) was exposed to light through a positive transparency having halftone dot iamage, developed with 3% aqueous solution of sodium sil.icate, washed with water and dried.
The exposed plate was processed in an automatic processor (Model 800 EB manufactured by PUJI PHOTO PILM CO., LTD.) having , . . .
;~0349~5 a developing zone provided with 3 ~ aqueous sodium silicate solution, to develop the exposed plates, and a finishing zone - provided with one part by volume of Gum solution I, II, III or~
IV prepared in step (b) and one part by volume of tap water, to apply each of the plate finishers to the developed plates immediately after the development without washing with water.
Lithographic printing plates were thus prepared.
These printing plates were previously allowed to stand for 3 days in a thermo-humidistat at a temperature of 45 C and a relative humidity (RH) of 85% or for 10 days at a room temperature~ Each of the plates was set on a printing press Heidelberg SOR-M and printing operation was conducted without removing the gum in an usual manner using dampening water containing 10 % isopropyl alcohol. The results are shown in Table 2.
03~965 Table 2 . ~xampleCompara1 .ive ~ amp]e Gum solution II III IV
The number of spoiled sheets (45 C, 85~, 3 days) 13 90 18 8 (lO days,room temp) lO 50 12 8 Background A A A B .
contamination Stability of stablestable separat- separat-gum solution ed in l ed in a year few days A: No or little background contamination B: Background contamination (non-image areas) Table 2 shows that Example 2 gave good results like Example l.
Example 3, 4 and 5 The same procedures as in Examples l and 2 were repeated except that benzyl alcohol in Gum solution I was replaced by ethylene glycol monophenyl ether, propylpropylene diglycol or n-amyl alcohol. The results are shown in Table 3.
20~9~i5 Table 3 _ xample Solvent S-l S-2 S-3 Amount (parts by weight) 25 35 20 Same procedures as spoiled sheets in Example 1 45 C , 85%, 3 days 20 22 30 room temp., 10 days 18 20 25 Background A A A
contamination Same procedures as spoiled sheets in Example 2 45 C , ~5%, 3 days 18 20 23 room temp., 10 days 15 15 18 Background A A A
contamination _ Stability good good good S-l: Ethylene glycol monophenyl ether S-2: Propylpropylene diglycol S-3: n-Amyl alcohol In all Examples, the number of spoiled printed matters was much smaller than Comparative Examples a and d and no background contamination was observed during printing.
The plate finisher of the present invention is excellent in the desensitizing ability and does not deteriorate the ink receptivity of image areas. Therefore, the lithographic printing plate to which the plate finisher of this invention is applied has good ink receptivity from the beginning of the printing operation. Moreover, the plate finisher of the invention is excellent in stability over time and can be prepared easily with an inexpensive equipment.
Claims (14)
1. A gumming-up process which comprises applying to a lithographic printing plate consisting of an oleophilic image area and a hydrophilic non-image area, a lithographic plate finisher comprising, in uniform admixture, at least one water-soluble resin, an organic solvent whose solubility in water at 20°C is not more than 5 % by weight, and water.
2. The process of claim 1 wherein the solvent whose solubility in water at 20°C is not more than 5 % by weight is selected from the group consisting of benzyl alcohol, ethylene glycol dibutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, hexyl glycol, hexyl diglycol, propyl propylene diglycol, methyl phenyl carbitol, diethylene glycol dibutyl ether, n-amyl alcohol, metyl amyl alcohol, isophorone, methyl cyclohexanone and acetophenone,
3. The process of claim 1 wherein the solvent is benzyl alcohol.
4. The process of claim 1 wherein the amount of the solvent used is 0.1 to 10 % by weight based on the total weight of the plate finisher.
5. The process of claim 1 wherein the amount of the solvent used is 0.5 to 5 % by weight based on the total weight of the plate finisher.
6. The process of claim 1 wherein said water-soluble resin is selected from the group consisting of starches derived from sweet potato, potato, tapioca, wheat, corn and waxy corn; those derived from carrageenan, laminaran, sea weed mannan, funori (a glue plant), Irish moss, agar and sodium alginate; mucilage derived from tororo-aoi mucin, mannan, quince seed mucin, pectin, tragacanth gum, karaya gum, xanthine gum, guar bean gum, locust bean gum, gum arabic, carob gum and benzoiun gum; dextran, glucan, levan, succinoglucan and xanthane gum; glue, gelatin, casein and collagen; propylene glycol alginate, viscose, methyl cellulose, ethyl cellulose, methyl ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and hydroxypropyl methyl cellulose phthalate; processed starches, enzyme-modified dextrin, acid-treated starch, oxidized, gelatinized starch, esterified, fatty acid starch, sulfuric acid starch, nitric acid starch, xanthogenic acid starch, carbamic acid starch and succinic acid starch, etherified starch, crosslinked, and starch graft copolymer; polyvinyl alcohol, modified polyvinyl alcohol, poly(meth)acrylic acid derivatives; polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl pyrrolidone-vinyl acetate copolymer, carboxy vinylpolymer, styrene-maleic acid copolymer and styrene-crotonic acid copolymer and is contained in an amount of 5 to 40 % based on the total weight of the plate finisher.
7. The process of claim 1 wherein said water-soluble resin comprises gum arabic in an amount of 1 to 20 % by weight based on the total weight of the water-soluble resin.
8. The process of claim 1 wherein the plate finisher further comprises at least one wetting agent selected from the group consisting of glycerin, ethylene glycol and triethylene glycol in an amount ranging from 0.1 to 5.0 % by weight based-on the total weight of the plate finisher.
9. The process of claim 1 wherein the plate finisher further comprises at least one surfactant selected from the group consisting of fatty acid salts, alkylbenzene sulfonic acid salts, straight chain alkylbenzene sulfonic acid salts, alkyl sulfonic acid salts, .alpha. -olefin sulfonic acid salts, alkyl phosphoric acid ester salts, dialkyl sulfo succinic acid ester salts, polyoxyethylene alkyl ether sulfonic acid salts, polyoxyethylene alkyl ether phophoric acid salts, alkylnaphthalene sulfonic acid salts, N-lauroyl sarcosine salts, sulfonic acid salts of condensates of naphthalene and formaldehyde, diphenylether disulfonic acid salts;
polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene-polyoxypropylene brock copolymers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene fatty acid amines, fatty acid monoglycerides, sorbitan fatty acid esters, pentaerythritol fatty acid esters, sucrose fatty acid esters, amine oxides;
alkylcarboxy betaines, alkylamino carboxylic acids, alkylimidazolines; tetraalkyl ammonium salts, trialkyl benzyl ammonium salts, alkyl imidazolinium salts; fluorine atom containing surfactants and silicon atom containing surfactants in an amount of 0.01 to 10% by weight based on the total weight of the plate finisher.
polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene-polyoxypropylene brock copolymers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene fatty acid amines, fatty acid monoglycerides, sorbitan fatty acid esters, pentaerythritol fatty acid esters, sucrose fatty acid esters, amine oxides;
alkylcarboxy betaines, alkylamino carboxylic acids, alkylimidazolines; tetraalkyl ammonium salts, trialkyl benzyl ammonium salts, alkyl imidazolinium salts; fluorine atom containing surfactants and silicon atom containing surfactants in an amount of 0.01 to 10% by weight based on the total weight of the plate finisher.
10. The process of claim 1 wherein the plate finisher further comprises at least one pH adjusting agent and has pH of 2 to 6.
11. The process of claim 1 wherein the plate finisher further comprises at least one preservative selected from the group consisting of benzoic acid, derivatives thereof, phenol, formalin, sodium dehydroacetate and 3-isothiazolones in an amount ranging from 0.005 to 2.0 % by weight of the plate finisher.
12. The process of claim 1 wherein the plate finisher further comprises at least one selected from the group consisting of anti-foaming agents, chelating agents and coloring agents.
13, The process of claim 1 wherein said lithographic printing plate is prepared by imagewise exposing to light a presensitized plate comprising an aluminum support having a lithographically suitable light-sensitive layer and then developing the imagewise exposed plate with a developing solution to remove the non-image area of the light-sensitive layer.
14. The process of claim 13 wherein said light-sensitive layer comprises a light-sensitive diazo resin and a polymeric binder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30474/1990 | 1990-02-09 | ||
| JP3047490A JPH03234595A (en) | 1990-02-09 | 1990-02-09 | Surface protectant for planographic printing plate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2034965A1 true CA2034965A1 (en) | 1991-08-10 |
Family
ID=12304858
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2034965 Abandoned CA2034965A1 (en) | 1990-02-09 | 1991-01-25 | Lithographic plate finisher |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0441502B2 (en) |
| JP (1) | JPH03234595A (en) |
| CA (1) | CA2034965A1 (en) |
| DE (1) | DE69106158T3 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19719936A1 (en) * | 1997-05-13 | 1998-11-19 | Fogra Forschungsgesellschaft D | Dampening solution for offset printing |
| JP2001138656A (en) * | 1999-11-10 | 2001-05-22 | Fuji Photo Film Co Ltd | Concentrated dampening water composition for lithographic printing |
| US20020187427A1 (en) | 2001-05-18 | 2002-12-12 | Ulrich Fiebag | Additive composition for both rinse water recycling in water recycling systems and simultaneous surface treatment of lithographic printing plates |
| DE102008025344A1 (en) | 2007-10-01 | 2009-04-02 | Heidelberger Druckmaschinen Ag | Re-imageable printing plate treatment method, involves removing developer i.e. rubber coating, before pre-allocation by using sodium hydroxide, caustic potash, ammonia, base, and hydrolyzing unit or by enzymatic shortening of polymers |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5266002A (en) * | 1975-11-26 | 1977-06-01 | Fuji Photo Film Co Ltd | Desensitizer for lithographic press plate |
| DE3006964A1 (en) * | 1980-02-25 | 1981-09-10 | Hoechst Ag, 6000 Frankfurt | LACQUER EMULSION AND METHOD FOR PRODUCING FLAT PRINTING FORMS |
| JPS5957793A (en) * | 1982-09-02 | 1984-04-03 | Konishiroku Photo Ind Co Ltd | Protective agent for printing surface of planographic printing plate |
| JPS5957242A (en) * | 1982-09-20 | 1984-04-02 | Konishiroku Photo Ind Co Ltd | Photoengraving method of lithographic printing plate |
| JPS6273269A (en) * | 1985-09-26 | 1987-04-03 | Konishiroku Photo Ind Co Ltd | Processing method for photosensitive lithographic printing plate |
| US4873174A (en) * | 1988-02-03 | 1989-10-10 | Hoechst Celanese Corporation | Method of using developer-finisher compositions for lithographic plates |
-
1990
- 1990-02-09 JP JP3047490A patent/JPH03234595A/en active Pending
-
1991
- 1991-01-24 EP EP19910300533 patent/EP0441502B2/en not_active Expired - Lifetime
- 1991-01-24 DE DE1991606158 patent/DE69106158T3/en not_active Expired - Fee Related
- 1991-01-25 CA CA 2034965 patent/CA2034965A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0441502A3 (en) | 1991-08-21 |
| JPH03234595A (en) | 1991-10-18 |
| DE69106158D1 (en) | 1995-02-09 |
| EP0441502B2 (en) | 1998-08-26 |
| DE69106158T3 (en) | 1999-02-25 |
| DE69106158T2 (en) | 1995-05-04 |
| EP0441502B1 (en) | 1994-12-28 |
| EP0441502A2 (en) | 1991-08-14 |
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| Date | Code | Title | Description |
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