JPH1165126A - Method for developing photosensitive lithographic printing plate and developer used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a photosensitive lithographic printing plate having a photosensitive layer of a photopolymerizable photosensitive resin composition formed on a surface of an aluminum plate support, and to deteriorate developing performance due to aging or repeated use. The present invention provides a method for developing a photosensitive lithographic printing plate capable of suppressing the image quality and preventing the non-image portion from being stained and obtaining good developability and strong image strength, and a developer used for the method. A lithographic printing plate in which a photosensitive layer of a photopolymerizable photosensitive resin composition comprising an ethylenically unsaturated bond-containing monomer, a photopolymerization initiator, and a polymer binder is formed on an aluminum plate support surface. Is an aqueous solution of alkali metal carbonate and bicarbonate after image exposure, having a pH of 8.5 to 1
1.5, a method for developing a photosensitive lithographic printing plate which is developed with a developer having a conductivity of 3 to 30 mS / cm, and a developer for the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing a photosensitive lithographic printing plate having a photosensitive layer of a photopolymerizable photosensitive resin composition formed on the surface of an aluminum plate support, and a developer used for the same. Is a method for developing a photosensitive lithographic printing plate that can suppress deterioration in developing performance due to aging or repeated use, does not stain the non-image area, and provides good developability and strong image strength. Liquid.

[0002]

2. Description of the Related Art Negative-working photosensitive lithographic printing plates, which have been widely used in the past, do not use an organic solvent for a developing solution because a photosensitive layer provided on the surface of an aluminum plate support is made of a diazo resin. Therefore, there is a concern about the treatment of the development waste liquid and its influence on the environment. Since the o-quinonediazide compound is used as a binder in the photosensitive layer of the positive photosensitive lithographic printing plate, an alkaline silicate aqueous solution capable of dissolving the novolak resin should be used as the developer. Can be. However, the pH of an alkaline developer capable of dissolving a novolak resin is about 13, and such a high-pH developer is highly irritating when adhered to skin or mucous membranes and requires careful handling during handling. . In addition, silicates are stable in the alkaline region, but have the drawback of gelling and insolubilizing at neutrality and dissolving only in strong acids such as hydrofluoric acid when evaporated to dryness. The contamination of the solidified matter due to the splash of the liquid around the developing tank of the developing machine and the precipitation of the insoluble matter due to the neutralization at the time of discarding the developing waste liquid are mentioned as the actual harm.

On the other hand, conventionally, a photosensitive lithographic printing plate having a photosensitive layer of a photopolymerizable photosensitive resin composition on the surface of an aluminum plate support is exposed to an image and then developed to form an image on the support. As the liquid, an aqueous solution of an alkali metal silicate, phosphate, carbonate, hydroxide, or the like, or an organic amine compound or the like is used. However, these conventional developing solutions are liable to deteriorate in developing performance over time and by repeated use, and also have insufficient removability of a photosensitive layer in a non-image area, resulting in poor developability and image quality. Strength does not always meet market requirements.

On the other hand, in order to suppress the deterioration of the developing performance due to aging and repeated use, Japanese Patent Application Laid-Open No.
No. 8377 proposes that the photosensitive resin composition layer formed on the surface of the glass substrate is developed with, for example, a mixed aqueous solution of sodium carbonate and sodium hydrogencarbonate having a pH of about 10. However, the inventor applied this developing solution to a photosensitive lithographic printing plate having a photosensitive layer of a photopolymerizable photosensitive resin composition on the surface of an aluminum plate support. However, good developability and strong image strength could not be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art.
In developing a photosensitive lithographic printing plate in which a photosensitive layer of a photopolymerizable photosensitive resin composition is formed on the surface of an aluminum plate support, a decrease in developing performance due to aging or repeated use is suppressed, and in a non-image area, It is an object of the present invention to provide a method for developing a photosensitive lithographic printing plate capable of obtaining good developability and strong image strength without staining, and a developer used for the method.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has used a specific photopolymerizable photosensitive resin composition constituting a photosensitive layer, and
It has been found that the object can be attained by developing using an aqueous solution of a mixture of an alkali metal carbonate and a hydrogen carbonate in which H is specified in a specific range and conductivity is specified in a specific range. Is completed. That is, the present invention provides a lithographic plate in which a photosensitive layer of a photopolymerizable photosensitive resin composition comprising an ethylenically unsaturated bond-containing monomer, a photopolymerization initiator, and a polymer binder is formed on the surface of an aluminum plate support. After imagewise exposing the printing plate, the printing plate is an aqueous solution of an alkali metal carbonate and a bicarbonate, and has a pH of 8.5 to 11.
5. A method for developing a photosensitive lithographic printing plate which is developed with a developer having a conductivity of 3 to 30 mS / cm, and a developer used for the method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, aluminum as an aluminum plate support means aluminum or its alloy, and its thickness is usually 0.05 to 1 m.
m. These aluminum plate supports are usually subjected to a surface treatment such as a degreasing treatment, a roughening treatment (graining treatment), an anodizing treatment, and a water washing treatment prior to the formation of a photosensitive layer on the surface thereof. .

[0008] The degreasing treatment is carried out by wiping with a solvent, dipping, and steam cleaning, dipping with an alkaline aqueous solution,
After spraying, a method of neutralization with an aqueous acid solution, immersion with a surfactant, and spraying are performed according to a conventional method such as a spraying method.
This is performed at a temperature of about 80 ° C. for a time of about 1 second to 1 minute.

The surface roughening treatment (graining treatment) to be performed is a mechanical treatment method such as a brush polishing method, a ball polishing method, a blast polishing method, a buff polishing method, an electrolytic etching method, a chemical etching method, and a liquid honing. According to a conventional method such as a method, the surface is usually roughened to a surface average roughness of about 0.1 to 1.5 μm. Among them, an electrolytic etching method in which electrolysis is performed by alternating current or direct current in a hydrochloric acid or nitric acid electrolytic solution is preferable.

[0010] Next, after desmutting with an acid or alkali aqueous solution, if necessary, the anodic oxidation treatment is performed by one or more of sulfuric acid, oxalic acid, phosphoric acid, chromic acid, malonic acid and the like. Is carried out by performing electrolysis using an aqueous solution containing an aluminum plate and an aluminum plate as an anode. The amount of an oxide film formed by the electrolysis is usually 1 to 50 mg / d.
m ² . Among them, a method in which an aqueous solution containing sulfuric acid is used as an electrolytic solution is preferable.
As described in JP 13894, the reaction is carried out at 5 to 50% by weight of sulfuric acid, at a temperature of 5 to 50 ° C, and at a current density of ¹ to 60 A / dm ² for about 5 to 60 seconds.

In the water washing treatment to be performed thereafter, tap water, ground water, or the like is used as it is or after softening, and is usually at room temperature to room temperature.
This is performed by showering, spraying, dipping, coating, or the like at a temperature of about 40 ° C. for a time of about 1 second to 5 minutes.

In the present invention, the monomer containing an ethylenically unsaturated bond as one component of the photopolymerizable photosensitive resin composition constituting the photosensitive layer formed on the surface-treated aluminum plate support is defined as When the photopolymerizable photosensitive resin composition is irradiated with actinic rays, it undergoes addition polymerization by the action of a photopolymerization initiator as another component, and in some cases, crosslinks, forms ethylenically unsaturated bonds such as to cure. Containing compound, and thus, the meaning of the monomer referred to herein is:
This is a concept corresponding to a so-called polymer, and includes not only monomers in a narrow sense but also dimers, trimers and oligomers.

Specific examples of the ethylenically unsaturated bond-containing monomer in the present invention include (1) acrylic acid and methacrylic acid (hereinafter, both are collectively referred to as “(meth) acrylic acid”). Unsaturated carboxylic acids such as (2) alkyl esters thereof, (meth) acrylonitrile, styrene, etc., and (3) ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth)
Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol di (meth) acrylate, glycerol tri (meth) acrylate And similar esters of aliphatic polyhydroxy compounds such as itaconates, crotonates, and maleates with unsaturated carboxylic acids;
(4) Ester of aromatic polyhydroxy compound such as hydroquinone di (meth) acrylate, resorcinol di (meth) acrylate, pyrogallol tri (meth) acrylate and unsaturated carboxylic acid, (5) Ethylene glycol and (meth) acrylic acid Polyhydroxy compounds such as condensates of phthalic acid, condensates of pentaerythritol, (meth) acrylic acid and terephthalic acid, and condensates of butanediol, glycerin, (meth) acrylic acid and adipic acid, and unsaturated carboxylic acids (6) a urethane (meth) acrylate such as an addition reaction product of a polyisocyanate compound such as tolylene diisocyanate and a hydroxyl group-containing (meth) acrylate such as hydroxyethyl (meth) acrylate; (7) Polyhydric epoxy compound and hydroxyethyl (meth) Epoxy (meth) acrylates such as addition products with hydroxyl-containing (meth) acrylates such as lylate, (8) acrylamides such as ethylenebis (meth) acrylamide, (9) allyl esters such as diallyl phthalate, (10) And vinyl group-containing compounds such as divinyl phthalate.

Further, as the preferred monomer containing an ethylenically unsaturated bond in the present invention, a monomer mixture of the above monomer containing an ethylenically unsaturated group and a phosphoric acid ester containing a (meth) acryloyl group can be mentioned. As the (meth) acryloyl group-containing phosphate, those represented by the following formula (1) are particularly preferable.

[0015]

Embedded image (Wherein, R ¹ represents a hydrogen atom or a methyl group, and n is 1
M represents 1 or 2; )

Among the compounds represented by the above formula (1), those used in the present invention may be used alone or as a mixture. It is particularly preferred from the viewpoint of the removability of, and specific examples include methacryloyloxyethyl phosphate, bis (methacryloyloxyethyl) phosphate and the like. In the present invention, the content of the (meth) acryloyl group-containing phosphate ester in the entire ethylenically unsaturated monomer is as follows:
It is preferably from 1 to 60% by weight, particularly preferably from 2 to 40% by weight. In this range, the exposure sensitivity as a photosensitive layer,
The printing durability is improved and the developability is improved.

In the present invention, specific examples of the photopolymerization initiator as one component of the photopolymerization type photosensitive resin composition constituting the photosensitive layer include dicyclopentadienyltitanium dichloride and dicyclopentadienyltitanium dichloride. Cyclopentadienyl titanium bisphenyl, dicyclopentadienyl titanium bis (2,4-difluorophenyl), dicyclopentadienyl titanium bis (2,6-difluorophenyl), dicyclopentadienyl titanium bis (2 4,6-trifluorophenyl), dicyclopentadienyl titanium bis (2,3,5,6-tetrafluorophenyl), dicyclopentadienyl titanium bis (2,3,4,5,6-pentafluoro Phenyl), di (methylcyclopentadienyl) titanium bis (2,6-difluorophenyl) Yl), di (methylcyclopentadienyl) titanium bis (2,3,4,5,6
-Pentafluorophenyl), titanocene compounds such as dicyclopentadienyltitanium bis (2,6-difluoro-3- (1-pyrrolyl) phenyl), and 2,
2'-bis (o-chlorophenyl) -4,4 ', 5
5′-tetra (p-chlorophenyl) biimidazole,
2,2′-bis (o-chlorophenyl) -4,4 ′,
5,5′-tetra (o, p-dichlorophenyl) biimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetra (o, p-dichlorophenyl) biimidazole , 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (p-fluorophenyl) biimidazole, 2,2'-bis (o-
(Chlorophenyl) -4,4 ′, 5,5′-tetra (o,
p-dibromophenyl) biimidazole, 2,2′-bis (o-bromophenyl) -4,4 ′, 5,5′-tetra (o, p-dichlorophenyl) biimidazole,
2'-bis (o-bromophenyl) -4,4 ', 5
5′-tetra (p-iodophenyl) biimidazole,
2,2′-bis (o-bromophenyl) -4,4 ′,
5,5′-tetra (o-chloro-p-methoxyphenyl) biimidazole, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetra (p-chloronaphthyl) biimidazole A hexaarylbiimidazole compound having a halogen-substituted aromatic ring such as is preferably used from the viewpoint of adhesion to a support as a photosensitive layer, exposure sensitivity, and storage stability. , Diaryliodonium salts, organic peroxides and the like.

In the present invention, specific examples of the polymer binder as one component of the photopolymerizable photosensitive resin composition constituting the photosensitive layer include (meth) acrylic acid and (meth) acrylic acid. Acrylic ester, (meth) acrylonitrile, (meth) acrylamide, maleic acid, styrene, vinyl acetate, vinylidene chloride, maleimide and other homo- or copolymers, and polyamide, polyester, polyether, polyurethane, polyvinyl butyral, polyvinyl pyrrolidone , Polyethylene oxide, acetyl cellulose and the like. Among them, a carboxyl group-containing polymer is preferable, and specifically, a copolymer of (meth) acrylic acid and (meth) acrylate is preferable, and the acid value of the carboxyl group-containing polymer is 10 to 10.
250, the weight average molecular weight is preferably 0.5 to 1,000,000.

Further, the polymer binder according to the present invention comprises:
It is preferable to have an ethylenically unsaturated bond in the side chain, and as the ethylenically unsaturated bond, those represented by the following formulas (2), (3) and (4) are particularly preferable. It is.

[0020]

Embedded image

(Wherein R ² represents a hydrogen atom or a methyl group, and R ^{3 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo Group, nitro group, cyano group, alkyl group optionally having substituent (s), aryl group optionally having substituent (s), alkoxy group optionally having substituent (s), having substituent (s) Aryloxy group which may be substituted, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, or
It represents an arylsulfonyl group which may have a substituent, and Z represents an oxygen atom, a sulfur atom, an imino group, or an alkylimino group. )

The polymer binder having an ethylenically unsaturated bond in the side chain represented by the above formula (2) is obtained by adding a carboxyl group-containing polymer to allyl glycidyl ether, glycidyl (meth) acrylate, α-ethyl glycidyl ( Meta)
Acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl crotonate, glycidyl isocrotonate, crotonyl glycidyl ether, monoalkyl monoglycidyl itaconate,
Aliphatic epoxy group-containing unsaturated compounds such as monoalkyl monoglycidyl fumarate and monoalkyl monoglycidyl maleate;
No. 9820, an alicyclic epoxy group-containing unsaturated compound, etc., at a temperature of about 80 to 120 ° C.,
After about 50 hours, the carboxyl group-containing polymer has 5 to 90 mol% of carboxyl groups, preferably 30
It is manufactured by reacting about 70 mol%.

The polymer binder having an ethylenically unsaturated bond represented by the formula (3) in the side chain includes allyl (meth) acrylate, 3-allyloxy-2-hydroxypropyl (meth) acrylate, cinnamyl A compound having two or more unsaturated groups such as (meth) acrylate, crotonyl (meth) acrylate, methallyl (meth) acrylate, and N, N-diallyl (meth) acrylamide; and a compound represented by the formula (4). Polymer binder having an ethylenically unsaturated bond in its side chain is vinyl (meth) acrylate, 1-chlorovinyl (meth) acrylate,
Compounds having two or more types of unsaturated groups, such as -phenylvinyl (meth) acrylate, 1-propenyl (meth) acrylate, vinylcrotonate, vinyl (meth) acrylamide, and unsaturated compounds such as (meth) acrylic acid, respectively. By copolymerizing a carboxylic acid or an unsaturated carboxylic acid ester so that the ratio of the former compound having an unsaturated group to the whole is 10 to 90 mol%, preferably about 30 to 80 mol%. Manufactured.

In the present invention, the proportions of the ethylenically unsaturated bond-containing monomer, the photopolymerization initiator, and the polymer binder as the photopolymerizable photosensitive resin composition constituting the photosensitive layer are as follows: Ethylenically unsaturated bond-containing monomer 10
The photopolymerization initiator is preferably 0.1 to 80 parts by weight, particularly 0.5 to 60 parts by weight, and the polymer binder is 10 to 400 parts by weight, particularly 20 to 100 parts by weight. 200
It is preferably in parts by weight.

In the present invention, the photopolymerizable photosensitive resin composition includes, in addition to the ethylenically unsaturated bond-containing monomer, the photopolymerization initiator, and the polymer binder, an active light In order to activate the photopolymerization initiator upon irradiation to effectively generate active radicals, for example, triphenylmethane-based leuco dyes such as leuco crystal violet and leucomalachite green disclosed in U.S. Pat. No. 3,479,185, Photoreducing dyes such as erythrosine and eosin Y; aminophenyl ketones such as Michler's ketone and aminostyryl ketone disclosed in US Pat. Nos. 3,549,367 and 3,652,275; and US Pat. No. 3,844,790. Β
Diketones, indanones disclosed in U.S. Pat. No. 4,162,162, ketocoumarins disclosed in JP-A-52-112681, and JP-A-59-5640.
3, aminophenyl derivatives and aminophenyl butadiene derivatives, aminophenyl heterocycles disclosed in U.S. Pat. No. 4,594,310, and julolidine heterocycles disclosed in U.S. Pat. No. 4,966,830. A sensitizer such as a pyrromethene dye disclosed in Japanese Unexamined Patent Publication No. 5-241338 is used in an amount of 0.01 to 20 parts by weight, especially 0.05 to 20 parts by weight, based on 100 parts by weight of the ethylenically unsaturated bond-containing monomer. It is preferable to use 10 parts by weight, and for the same purpose, for example, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole,
-Mercaptobenzoxazole, 3-mercapto-
1,2,4-triazole, N-phenylglycine,
It is preferable to use 0.01 to 30 parts by weight, particularly 0.05 to 20 parts by weight of a hydrogen-donating compound such as an alkyl N, N-dialkylaminobenzoate.

The photopolymerizable photosensitive resin composition may further comprise, if necessary, various additives such as hydroquinone, p-methoxyphenol, and 2,6-di-tert-butyl-p-cresol. 2 parts by weight or less of a polymerization inhibitor, 20 parts by weight or less of a coloring agent composed of an organic or inorganic dye or pigment, 40 parts by weight or less of a plasticizer such as dioctyl phthalate, didodecyl phthalate, and tricresyl phosphate.
A sensitivity improving agent such as a tertiary amine or thiol, or a dye precursor or the like may be added in an amount of 30 parts by weight or less.

The photopolymerizable photosensitive resin composition of the present invention comprises the above ethylenically unsaturated bond-containing monomer, the photopolymerization initiator, the polymer binder, the sensitizer, Hydrogen donating compound, the additive and the like, for example, cyclohexanone, propylene glycol monomethyl ether acetate, as a solution of a solvent such as ethanol, for example, dip coating, coating rod,
By applying and drying the surface of the aluminum plate support to a thickness of about 0.1 to 10 g / m ² by a conventionally known method such as spinner coating, spray coating, roll coating, or the like, the photosensitive material is dried. Used as a photosensitive layer for lithographic printing plates.

At this time, in order to protect the photosensitive layer,
A material such as Teflon is suitably used as a member that comes into contact with the photosensitive layer such as a transport roll of the plate after coating. Also,
Usually, an oxygen shielding layer of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, cellulose or the like is provided on the photosensitive layer in order to prevent a polymerization inhibition effect by oxygen.

The photosensitive layer of the photopolymerizable photosensitive resin composition according to the present invention may be formed, for example, by using a carbon arc, high pressure mercury lamp, xenon lamp, metal halide lamp, fluorescent lamp, tungsten lamp, halogen lamp, helium cadmium laser, argon ion laser. An image can be formed on the surface of the aluminum plate support by performing image exposure with a conventionally known active light source such as a YAG laser, a helium neon laser or the like, followed by development.

The developer used in the development of the present invention is an aqueous solution of an alkali metal carbonate and a hydrogen carbonate,
H 8.5 to 11.5, conductivity 3 to 30 mS / cm. Here, examples of the alkali metal include lithium, sodium, and potassium, among which sodium is preferable. Further, the pH is essential to be 8.5 to 11.5, preferably 9.0 to 11.0,
More preferably, it is 9.0 to 10.5. Further, the conductivity is essential to be 3 to 30 mS / cm,
It is preferably 5 to 25 mS / cm, and 8 to 20 mS.
/ Cm, more preferably 10 to 17 mS / cm.
cm is particularly preferred.

When the developing solution is composed of an alkali metal salt other than a mixture of carbonate and hydrogen carbonate, even if the pH and the conductivity are in the above-mentioned ranges, the developing performance is deteriorated by aging and repeated use. Further, even when the mixture is made of a mixture of carbonate and bicarbonate, if the pH falls below the above range, image formation becomes impossible, and if the pH exceeds the above range,
Deterioration due to carbon dioxide gas in the air causes a decrease in developing performance. Further, when the conductivity is below the above range, it is difficult to elute the photosensitive resin composition on the surface of the aluminum plate support and image formation cannot be performed, and when the conductivity exceeds the above range, a residual film may be formed on a non-image portion. In any case, the developing performance decreases.

The developer may be prepared by adding and dissolving both alkali metal carbonate and bicarbonate in the same water, or by mixing the respective aqueous solutions. You may.

The above-mentioned developer may contain, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene alkyl ester, if necessary, for the purpose of improving image quality and shortening the development time. , Nonionics such as sorbitan alkyl esters and monoglyceride alkyl esters, anionics such as alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfates, alkyl sulfonates, sulfosuccinates, alkyl betaines, and amino acids Amphoteric surfactants such as isopropyl alcohol, benzyl alcohol, ethyl cellosolve, butyl cellosolve, phenyl cellosolve, propylene glycol, diacetone alcohol, etc., water-soluble organic solvents, hydroxyl groups Others may be added low molecular compound having a carboxyl group, a defoaming agent, a hard water softening agent or the like.

The development of the photosensitive lithographic printing plate according to the present invention with the developing solution is carried out in a conventional manner at a temperature of 0 to 60 ° C., preferably 15 to 45 ° C., for example, by subjecting the exposed lithographic printing plate to a developing solution. This is performed by immersion in At this time, the concentration of the alkali metal carbonate in the developing solution was A (mol / liter), and the concentration of the alkali metal bicarbonate was B.
(Mol / liter) and the liquid temperature is defined as T (° C.), and the development is performed under conditions that simultaneously satisfy the following three expressions, whereby a decrease in the developing performance of the developer due to repeated use can be suppressed. 0.0001 ≦ A ≦ 10 ≦ T ≦ 60 (100-T) A ^0.6 / 2 ≦ 75B ≦ (100-T) A
^0.6

That is, an alkali metal carbonate (M ₂ C)
O ₃ ) aqueous solution and alkali metal bicarbonate (MHC)
O ₃₎ in a mixture of an aqueous solution, both together completely dissociated into ^{_{ions, M +, CO 3 2-,}} HCO 3 - produce ionic species such. Then, HCO ₃ ⁻ + H ⁺ → (←) H
Due to the equilibrium reaction of ₂ CO ₃ , M ⁺ , CO
An equilibrium exists between ₃ ²⁻ and HCO ₃ ⁻ . Therefore, M
_If the ratio of the ₂ CO ₃ aqueous solution and the MHCO ₃ aqueous solution is appropriately selected to adjust the pH of the mixed aqueous solution to a predetermined range,
The concentration of H ₂ CO ₃ can be balanced with the partial pressure of CO _{2 in} the air to sufficiently suppress the absorption and release of CO ₂ ,
This is possible when the above three equations are simultaneously satisfied. Here, it is sufficient that each component exists in a state of being dissolved in water, and it is not essential that each component exist in a state of not dissociating.

The photosensitive lithographic printing plate developed with a developing solution is usually a rinsing solution containing washing water, a surfactant and the like.
Post-treatment with a finisher or protective gum solution containing gum arabic or a starch derivative as a main component.

[0037]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In addition, the aluminum plate support used, the monomer containing an ethylenically unsaturated bond, a photopolymerization initiator, and a polymer binder, and a developer,
It is as follows.

Aluminum plate support A support was degreased with 3% by weight of sodium hydroxide.
25 ° C., 80 A / d in 11.5 g / liter hydrochloric acid bath
electrolytic etching at a current density of 1 m ² for 11 seconds, washing with water, and then in a 30% by weight sulfuric acid bath at 30 ° C., 11.5 g / dm 2
^An anodized, washed, and dried support at a current density of ² for 15 seconds. Support The support was further hydrophilized at 85 ° C. for 30 seconds with a 1% by weight aqueous solution of sodium metasilicate, washed with water and dried.

Ethylenic unsaturated bond-containing monomer Monomer The following compound.

[0040]

Embedded image (However, a + b ≒ 4) Monomer The following compound.

[0041]

Embedded image (However, it is a mixture of those having c = 6 and d = 0 and those having c = 5 and d = 1.) Monomer The following compound.

[0042]

Embedded image Monomer The following compound.

[0043]

Embedded image (However, the molar ratio of m = 1 and m = 2 is 1: 1.)
Is a mixture of )

Photopolymerization initiator The following compound

[0045]

Embedded image

Polymer Binder Polymer Binder Methyl methacrylate (35 mol%) / isobutyl methacrylate (20 mol%) / isobutyl acrylate (10 mol%) / methacrylic acid (35 mol%) copolymer (weight average molecular weight 7 Ten thousand). Polymer Binder A reaction product (60 oxidation, 60 carboxyl group of methacrylic acid component) obtained by reacting the polymer binder with 3,4-epoxycyclohexylmethyl acrylate.
Mole% reacted).

Polymer binder Vinyl methacrylate (60 mol%) / methyl methacrylate (20 mol%) / methacrylic acid (20 mol%) copolymer (weight average molecular weight: 140,000).

[0048] Dissolve developer developer sodium 0.003 mol and sodium bicarbonate 0.01 mol carbonate in 1 liter of water, surfactant (Takemoto Oil & Fat Co., "PIONIN A-41B") was added 20g aqueous solution (PH 9.3, conductivity 2.6 mS / c
m). Developing solution An aqueous solution containing 5 g of sodium chloride (pH
9.3, conductivity 11 mS / cm). Developer 0.03 mol of sodium carbonate and 0.
An aqueous solution (pH 9.3, conductivity 12 mS / cm) obtained by dissolving 10 moles in 1 liter of water and adding 80 ml of a surfactant ("Perex NBL" manufactured by Kao Corporation). Developer 0.04 mol of sodium carbonate and 0.1 mol of sodium bicarbonate.
An aqueous solution (pH 9.3, conductivity 22 mS / cm) obtained by dissolving 24 moles in 1 liter of water and adding 50 ml of a surfactant ("Perex NBL", manufactured by Kao Corporation). Developer 0.18 mol of sodium carbonate and 0.1 mol of sodium hydrogen carbonate.
An aqueous solution (pH 9.3, conductivity 60 mS / cm) obtained by dissolving 60 mol in 1 liter of water and adding 80 ml of a surfactant ("Perex NBL" manufactured by Kao Corporation). Developer 0.07 mol of sodium carbonate and 0.1 mol of sodium bicarbonate.
08 mol was dissolved in 1 liter of water, and an aqueous solution (pH 10.3, conductivity 15 mS / cm) to which 80 ml of a surfactant ("Perex NBL" manufactured by Kao Corporation) was added. Developer Solution An aqueous solution (pH 11.5, conductivity 10 mS /) obtained by dissolving 5 g of sodium carbonate in 1 liter of water and adding 50 ml of a surfactant (“Perex NBL” manufactured by Kao Corporation).
cm). Developer: 5.32 g of potassium hydroxide (85% grain), 14.99 g of potassium A silicate, 15.21 g of a surfactant ("Perex NBL", manufactured by Kao Corporation), and 3 g of pt-butylbenzoic acid in 260 g of water Aqueous solution (pH 1
3.8, conductivity 45 mS / cm).

Examples 1 to 5 and Comparative Examples 1 to 3 As shown in Table 1, a mixture of ethylenically unsaturated bond-containing monomers was used. 18.2 parts by weight, 81.8 parts by weight of polymer binder,
Further, 5.5 parts by weight of a sensitizer represented by the following formula,

[0050]

Embedded image

9.1 parts by weight of 2-mercaptobenzothiazole, 18.2 parts by weight of ethyl N, N-dimethylaminobenzoate, 5.5 parts by weight of copper phthalocyanine pigment,
Each of the photopolymerizable photosensitive resin composition coating solutions to which 1982 parts by weight of cyclohexanone was added was applied to a support shown in Table 1 using a bar coater so that the dry film thickness was 2 g / m ^2, and dried. Then, a polyvinyl alcohol aqueous solution was further dried thereon using a bar coater to a dry film thickness of 3 g.
/ M ² and dried to prepare a photosensitive lithographic printing plate.

For each of the obtained photosensitive lithographic printing plates, a diffraction spectral irradiation device (“RM-2” manufactured by Narumi Co., Ltd.) was used.
3)), and using a developer shown in Table 1
The film was developed at 5 ° C., and the amount of light energy required for photopolymerization and curing by a light beam having a wavelength of 488 nm was determined from the height of the obtained polymerization and cured images, and the exposure sensitivity was evaluated. Also, for each of the resulting photosensitive lithographic printing plates, unexposed,
After immersion in a developer shown in Table 1 at 25 ° C. for 30 seconds and development by rubbing with a sponge five times, one drop of methylcellosolve was dropped and dried, and a developing ink (manufactured by Konica, “SPO-1” )), The ink deposition on the non-image area was observed, and the developability was evaluated. The level at which no ink was deposited was represented by ○, the level at which fringes were generated at the methylcellosolve dropping marks was Δ, and the level at which the ink was entirely deposited was ×.

Further, each of the obtained photosensitive lithographic printing plates was subjected to an air-cooled argon laser (manufactured by Dainippon Screen Co., Ltd.).
After performing a scanning exposure with an exposure amount of “PI-R”) of 100 μj / cm ² , development processing was performed at 25 ° C. using a developer shown in Table 1, and the reproducibility of 1% small point was evaluated. A level that completely reproduces a point is indicated by 、, a level that partially reproduces a small point but a part of the small point is slightly narrow is indicated by Δ, and a level that does not partially reproduce a small point is indicated by × . Subsequently, the obtained lithographic printing plate was printed on a printing machine (“DAIYA-1F” manufactured by Mitsubishi Heavy Industries, Ltd.).
"-2 type"), and the printing durability was evaluated by the number of printed sheets until the image area (120 lines, 4% small point) jumped. Table 1 shows the evaluation results of the above exposure sensitivity, developability, small dot reproducibility, and printing durability.

[0054]

[Table 1]

Examples 6 and 7, Comparative Examples 4 and 5 With respect to the photosensitive lithographic printing plate prepared in the same manner as in Example 2 except that the polyvinyl alcohol layer was not provided, the respective developing solutions shown in Table 2 were used. The development was performed at 25 ° C., and the degree of decrease in developability due to repeated use of the developer was evaluated by measuring the development time, pH, and ΔOH amount. In addition, the pH of each developer after leaving it overnight was also measured. Table 2 shows the obtained results.

[0056]

[Table 2]

Examples 8-9, Comparative Examples 6-7 Photosensitive lithographic printing plates prepared in the same manner as in Example 2 except that no polyvinyl alcohol layer was provided using the above-mentioned developer (Example 8) A photosensitive lithographic printing plate prepared in the same manner as in Example 2 (Example 9) except that the polyvinyl alcohol layer was not provided and the support was used, and a novolak-based positive photosensitive lithographic printing plate Plate (Mitsubishi Chemical Co., Ltd., "PM-1") (Comparative Example 6), diazo negative photosensitive lithographic printing plate (Mitsubishi Chemical Co., Ltd., "NW-
1)) (Comparative Example 7), developability was evaluated in the same manner as in the above Examples. As a result, in Examples 8 and 9, the result was 、, in Comparative Example 6, development was impossible, and in Comparative Example 7, it was ×.

[0058]

According to the present invention, in developing a photosensitive lithographic printing plate in which a photosensitive layer of a photopolymerizable photosensitive resin composition is formed on the surface of an aluminum plate support, the development performance by aging or repeated use is improved. And a method for developing a photosensitive lithographic printing plate capable of obtaining a good developing property and strong image strength while preventing the non-image portion from being stained, and a developing solution used therefor.

Claims (7)

[Claims] 1. Lithographic printing wherein a photosensitive layer of a photopolymerizable photosensitive resin composition comprising an ethylenically unsaturated bond-containing monomer, a photopolymerization initiator, and a polymer binder is formed on the surface of an aluminum plate support. After imagewise exposing the plate, it is an aqueous solution of an alkali metal carbonate and hydrogencarbonate, having a pH of 8.5 to 1
1.5. A method for developing a photosensitive lithographic printing plate, comprising developing with a developer having a conductivity of 3 to 30 mS / cm. 2. The method for developing a photosensitive lithographic printing plate according to claim 1, wherein the polymer binder comprises a carboxyl group-containing polymer. 3. The method for developing a photosensitive lithographic printing plate according to claim 2, wherein the carboxyl group-containing polymer has an ethylenically unsaturated bond in a side chain. 4. The photosensitive lithographic printing plate according to claim 1, wherein the ethylenically unsaturated bond-containing monomer is a monomer mixture containing an acryloyl group or a methacryloyl group-containing phosphoric acid ester. Development method. 5. The developer according to claim 1, wherein the concentration of the alkali metal carbonate is A (mol / liter), the concentration of the alkali metal bicarbonate is B (mol / liter), and the liquid temperature is T (° C.).
5. The method according to claim 1, wherein the following three expressions are simultaneously satisfied.
The method for developing a photosensitive lithographic printing plate according to any one of the above. 0.0001 ≦ A ≦ 10 ≦ T ≦ 60 (100-T) A ^0.6 / 2 ≦ 75B ≦ (100-T) A
^0.6 6. The method for developing a photosensitive lithographic printing plate according to claim 1, wherein the surface of the aluminum plate support is electrolytically polished. 7. Lithographic printing wherein a photosensitive layer of a photopolymerizable photosensitive resin composition comprising an ethylenically unsaturated bond-containing monomer, a photopolymerization initiator and a polymer binder is formed on the surface of an aluminum plate support. A plate developer having a pH of 8.5 to 1;
1.5. A photosensitive lithographic printing plate developer comprising an aqueous solution of an alkali metal carbonate and a hydrogen carbonate having an electric conductivity of 3 to 30 mS / cm.