JPH08234424A - Original plate of photosensitive planographic printing plate and production of planographic printing plate - Google Patents

Abstract

PURPOSE: To enhance the ink receptivity of an image line area and to make it basically possible to produce a printing plate only by washing the surface of an original plate by incorporating a lipophilic ethylenically unsatd. compd. into a hydrophilic swellable layer. CONSTITUTION: In the original plate of a photosensitive planographic printing plate with at least a photosensitive hydrophilic swellable layer on the substrate, a lipophilic ethylenically unsatd. compd. is incorporated into the hydrophilic swellable layer. The lipophilic ethylenically unsatd. compd. means a photopolymerizable monomer or oligomer having <=8wt.% solubility to water at 20 deg.C and a compd. represented by the formula CH2 =C(R<1> )-CO-O-(CH2 )n -R<2> is preferably used as the ethylenically unsatd. compd. In the formula, R<1> is H or methyl, R<2> is H, a 1-20C optionally substd. alkyl, nitro, azido, 2-20C alkenyl, 4-20C optionally substd. aryl, etc., and (n) is an integer of 1-30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive lithographic printing plate precursor, which has a high ink repulsion property without desensitizing treatment and is a novel photosensitive material capable of using pure water as fountain solution. It relates to a lithographic printing plate.

[0002]

2. Description of the Related Art In planographic printing, the image area and the non-image area are basically on the same plane, and the image area is ink-receptive and the non-image area is ink repellent. After applying ink to only the image area using the difference in adhesion,
It means a method of printing by transferring ink to a printing medium such as paper. A PS plate is usually used for such lithographic printing.

The PS plate here means the following.

[0004] That is, Teruhiko Yonezawa "PS Version Overview"
As described in pp. 18-p81 of Press Society of Japan Press (1993), a lipophilic photosensitive resin layer is coated on a hydrophilically treated aluminum substrate, and an image area is formed by a photolithography technique. The photosensitive layer remains, while the non-image area exposes the surface of the above-mentioned aluminum substrate, forms a dampening water layer on the surface, repels ink, and forms a water image on the PS plate and the dampening water layer. Instead, a waterless PS plate using a silicone rubber layer as an ink repellent layer, a so-called waterless planographic plate.

The waterless lithographic printing plate referred to herein is composed of a substance having a non-image area such as silicone rubber and a fluorine-containing compound, which has ink repulsion property with respect to an oil-based ink usually used in lithographic printing. It means a printing plate capable of forming an image with an ink-receptive image portion without using it and printing.

The former PS plate with water is a printing plate which is excellent in practical use, and aluminum is usually used for the support, and the surface of the aluminum has water retentivity and a lipophilic photosensitive resin layer is formed on the surface during printing. It was necessary to have excellent adhesiveness to the photosensitive layer so as not to peel off. Therefore, the aluminum surface is usually grained, and if necessary, the grained surface is subjected to a treatment such as anodic oxidation to improve water retention and reinforcement of adhesiveness to the photosensitive resin layer. Has been. Further, in order to obtain the storage stability of the photosensitive resin layer, the aluminum surface is generally subjected to a chemical treatment with zirconium fluoride, sodium silicate or the like.

As described above, the PS plate with water has a complicated manufacturing process and its simplification has been desired, but it is widely used because of its excellent printing characteristics (printing durability, image reproducibility, etc.). There is.

In order to solve the above problems, there has been proposed a novel lithographic material which has a printing characteristic equal to or better than that of an aluminum substrate, has a low material cost, and is different from the aluminum substrate by a simple manufacturing process. For example, Japanese Patent Publication No. 56-2938 proposes a method in which a support having an ink repellent layer made of a hydrophilic polymer material coated thereon is used instead of an aluminum substrate, and a photosensitive layer is formed on the support. ing. However, in this method, the urea resin is simply applied as a hydrophilic layer on the water-resistant layer of the aldehyde condensate of polyvinyl chloride, polyurethane, or polyvinyl alcohol, so that the layer has insufficient ink repulsion. In addition, the adhesiveness to the photosensitive resin layer was poor, and the printing durability was insufficient. Further, in JP-A-57-179852, a hydrophilic radical polymerization compound is coated on a support, the surface of the support is hydrophilized by irradiation with an actinic ray, and a photosensitive resin layer is coated. A method has been proposed. However, the hydrophilic surface layer formed by this method is also rigid, the ink repulsion property is insufficient, and the printing durability is also poor.

In developing these PS plates with water, it is necessary to dissolve the components of the photosensitive layer in a developing solution because it is a system in which the surface of the aluminum substrate is exposed by dissolving the photosensitive layer. Causes a large compositional change in a short period of time and causes fatigue, so a large amount of developing waste liquid is generated.

Therefore, the developing solution has to be frequently maintained and replaced. Further, a great deal of labor and cost are required for processing the generated developing waste liquid.

As a simple form of the PS plate with water,
An image receiving layer such as toner is provided on a support such as paper
A direct-drawing type lithographic printing original plate, which is used by forming an image using a PC and converting the image receiving layer into an ink repellent layer by desensitizing the non-image portion with an etchant or the like, is widely used in practice. . Specifically, it is common to provide an image receiving layer composed of a water-soluble binder polymer, an inorganic pigment, a water-proofing agent and the like on a water-resistant support. USP 2532865, JP-B-40-23581, and JP-A-40-23581 JP-A-48-9802, JP-A-57-205196, and JP-A-60-2
309, JP-A-57-1791, JP-A-5
7-15998, JP-A-57-96900, JP-A-57-205196, and JP-A-63-1.
66590, JP-A-63-166591,
JP-A-63-317388, JP-A-11144
88, Japanese Patent Laid-Open No. 4-368868 and the like. These direct drawing type lithographic printing plates are used as an image receiving layer to be converted into an ink repellent layer, as PVA, starch, hydroxyethyl cellulose, casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer, styrene-maleic acid copolymer. Water-soluble binder polymers and hydrophilic water-dispersible polymers such as acrylic resin emulsions, inorganic pigments such as silica and calcium carbonate, and melamine-formaldehyde resin condensates before desensitizing treatment such as coalescence It is proposed that the water resistant agent is used. In addition, JP-A-63-2
In Japanese Patent No. 56493 or the like, a direct drawing type lithographic printing plate precursor is proposed which uses as a main component a hydrophobic polymer which is hydrolyzed by a desensitizing treatment to generate a hydrophilic group.

[0012] In all of such a direct drawing type lithographic printing plate precursor, desensitization treatment is indispensable in order to convert the image receiving layer into an ink repellent layer, and without such treatment, ink repellent property is hardly exhibited. It was the one.

That is, in order to obtain a practical level of ink repulsion, it is necessary to desensitize and use a large amount of a hydrophilic binder polymer, but the water resistance tends to be poor and the printing durability will deteriorate. . Further, when the hydrophilicity is increased, there is a problem that the adhesiveness to an image such as a toner tends to decrease. On the other hand, if water resistance is increased by increasing the amount of waterproofing agent added or adding a hydrophobic polymer to improve printing durability, hydrophilicity decreases and ink repulsion decreases significantly. There was a problem that caused it.

Further, a so-called one-step exposure-only technique developed by Union Carbide that does not require development, lacquer deposition and desensitizing treatment utilizing a hydrophilic / hydrophobic conversion reaction is disclosed in Japanese Patent Publication No. 42-42. No. 131, Japanese Patent Publication No. 4
No. 2-5365, Japanese Patent Publication No. 42-14328,
Japanese Examined Patent Publication No. 42-20127, USP 3231377.
Publication, USP3231381 Publication, USP3231
No. 382 and the like. The plate is formed by coating an aggregate of polyethylene oxide and a phenol resin together with a photosensitizer, but the non-image area is rigid and inferior in flexibility, and the ink repulsion is insufficient, and the non-image area and the image area are Ink repulsion / ink inking difference between the line part is small,
It was poor in practicality.

Further, in the PS plate with water, it is necessary to constantly control the amount of dampening water during printing, and considerable skill and experience have been required to control an appropriate amount of dampening water. IPA added to dampening water as an essential component
In recent years, the use of (isopropanol) has been severely regulated from the standpoint of the occupational health environment and wastewater treatment, and countermeasures against it are urgently needed.

On the other hand, in the latter case of a waterless PS plate having a silicone rubber layer as an ink repellent layer instead of dampening water, JP-B-54-26923, JP-B-57-3060 and JP-B-56-12862. Publication, Japanese Patent Publication No. 56-23
150, JP-B 56-30856, JP-B 60-60051, JP-B 61-54220, JP-B 61-54222, and JP-B 61-54.
223, Japanese Patent Publication No. 61-616, Japanese Patent Publication No. 63
No. 23544, No. 2-25498, No. 3-56622, No. 4-28098, No. 5-1934, and No. 2-63050.
As described in Japanese Patent Publication No. 2-63051 and Japanese Patent Laid-Open No. 2-63051, it is possible to print without using dampening water, so the former printing with PS plate does not require any dampening water control work. Since the work is extremely simple, it is a plate material with high practicality that is rapidly spreading in recent years, but due to the use of a silicone rubber layer with weak mechanical strength as the ink repellent layer, lack of durability is pointed out. There is a strong demand for ink repellent materials with excellent durability. Further, during development, the silicone rubber layer needs to be mechanically peeled and removed by rubbing with a brush, so that a large amount of development waste liquid containing the peeled and removed silicone rubber residue is generated. Therefore, the service life of the brush is short, and it is necessary to replace the brush frequently, and maintenance measures such as collecting and discarding the silicone rubber residue are required.

[0017]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention have expanded the control range of the fountain solution in the conventional lithographic printing of PS plates with water, and made IPA-less from the fountain solution, which has hitherto been impossible. In addition, a waterless planographic printing plate in which a silicone rubber layer is used as an ink repellent layer is provided without a complicated plate making process such as image formation by a PPC method and desensitizing treatment like a direct drawing planographic printing original plate. As a result of diligent studies to develop an ideal lithographic material that can solve the shortcoming of lack of durability, which does not require the development and maintenance that was necessary for conventional PS plates, and has a simple manufacturing process, a specific material It has been found that it can be realized by using a hydrophilic swelling layer having a phase separation structure composed of a group as an ink repellent layer and using a lipophilic ethylenically unsaturated compound as a photosensitive component.

[0018]

That is, the present invention has the following configuration.

(1) A photosensitive lithographic printing plate precursor having at least a photosensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer contains a lipophilic ethylenically unsaturated compound. Photosensitive lithographic printing plate precursor.

(2) The hydrophilic swelling layer has a phase-separated structure composed of at least two phases including a phase mainly containing a hydrophilic polymer and a phase mainly containing a hydrophobic polymer. (1) The photosensitive lithographic printing plate precursor as described above.

(3) The photosensitive lithographic printing plate precursor as described in (1) above, which has a protective layer on the hydrophilic swelling layer.

(4) A lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer at the portion corresponding to the image area is obtained by irradiating the plate surface of the photosensitive lithographic printing plate precursor as described in (1) above with an actinic ray. Is photocured, and then the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer in the portion corresponding to the non-image area is removed.

(5) Removal of the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer at the portion corresponding to the non-image area,
The method for producing a lithographic printing plate as described in (4) above, which is carried out by washing the entire plate with water.

The hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention will be described.

The hydrophilic swelling layer is photosensitive and contains a lipophilic ethylenically unsaturated compound as a photosensitive compound.

The lipophilic ethylenically unsaturated compound of the present invention will be described.

The lipophilic ethylenically unsaturated compound of the present invention means a photopolymerizable monomer or oligomer having a solubility in water of 8% by weight or less at 20 ° C.

Specific examples of the lipophilic ethylenically unsaturated compound preferably used in the present invention include compounds represented by the following general formula (I).

CH ₂ ═C (R ¹ ) —CO—O— (CH ₂ ) _n —R ² (I) (wherein R ¹ represents hydrogen or a methyl group. R ² is hydrogen and has 1 to 1 carbon atoms). 20 substituted or unsubstituted alkyl group, nitro group, azido group, alkenyl group having 2 to 20 carbon atoms, substituted or unsubstituted aryl group having 4 to 20 carbon atoms,
It represents a substituted or unsubstituted aralkyl group, acryloxy group, or methacryloyloxy group. n is an integer of 1 to 30. The following compounds may be mentioned as specific examples.

[0030]

Embedded image n means the average value of the compound represented by the above general formula. That is, the compound represented by the above general formula is a mixture having a distribution in n.

From the viewpoint of ink receptivity, these compounds are n
Is preferably an integer of 4 to 30, and more preferably 8 to 13. When n is 3 or less, lipophilicity tends to be insufficient and ink receptivity tends to be insufficient. When n is 31 or more, the unsaturated group equivalent per weight is insufficient and the photosensitivity is lowered. For example, n is 4,5,6,7,8,9,10,1
Compounds such as 3,22 can be used.

Specific examples of the lipophilic ethylenically unsaturated compounds other than the above-mentioned general formula (I) which are preferably used in the present invention include 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, neopentyl glycol diacrylate and neopentyl. Examples thereof include glycol dimethacrylate, isooctyl acrylate, isooctyl methacrylate and the like.

These lipophilic ethylenically unsaturated compounds can be used alone or in admixture of two or more.

These lipophilic ethylenically unsaturated compounds preferably used in the present invention are added to the composition at the time of forming the hydrophilic swelling layer and allowed to exist in the layer, or the hydrophilic swelling layer is added. After formation, the compound is added onto the layer by diluting with a suitable solvent which easily penetrates into the hydrophilic swelling layer, if necessary, and impregnating into the layer.

When a relatively high molecular weight oligomer or the like is used, the former method of simultaneously adding the hydrophilic swelling layer is advantageously performed, and when a relatively low molecular weight monomer or oligomer is used, the latter method is used. The method of impregnation is advantageous.

The hydrophilic swelling layer used in the photosensitive lithographic printing plate precursor according to the present invention is a phase separation composed of at least two phases of a hydrophilic polymer as a main component and a hydrophobic polymer as a main component. It is preferable to have a structure.

The hydrophilic polymer used in the hydrophilic swelling layer of the present invention will be described.

The hydrophilic polymer is a known water-soluble polymer (meaning one completely soluble in water) or a pseudo-water-soluble polymer (amphipathic polymer) which is substantially insoluble in water and shows water swelling property. The macro means that it is soluble in water, but the micro means that it contains an insoluble portion, and the water-swellable polymer (means that it swells in water but does not dissolve).
That is, it means a polymer that adsorbs or absorbs water under normal use conditions, and a polymer that dissolves in water or swells in water.

Examples of the hydrophilic polymer that effectively exhibits the effects of the present invention include carboxylate salt copolymers.

The carboxylic acid salt-based copolymer preferably used in the present invention is, from the viewpoint of water absorption and durability,
Monomers of α, β-unsaturated compounds having one or two carboxyl groups or groups capable of being converted into a carboxyl group in a molecule, such as carboxyl groups, carboxylate salts, carboxylic acid amides, carboxylic acid imides, and carboxylic acid anhydrides. A saponification reaction product of a carboxylic acid-based copolymer contained as a component may be mentioned.

Specific examples of the α, β-unsaturated compound include:
Acrylic acid, methacrylic acid, acrylic acid amide, methacrylic acid amide, maleic anhydride, maleic acid, maleic acid amide, maleic acid imide, itaconic acid, crotonic acid, fumaric acid, mesaconic acid and the like, which are necessary for the present invention. It is possible to combine with another monomer component which is copolymerizable within the range showing hydrophilicity.

Examples of other copolymerizable monomer components include α, such as ethylene, propylene, isobutylene, 1-butylene, diisobutylene, methyl vinyl ether, styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester and acrylonitrile. Examples thereof include olefins, vinyl compounds and vinylidene compounds.

When combined with another monomer, the α, β-unsaturated compound containing a carboxyl group or a group convertible to this is usually 10 mol% or more in all the monomer components,
It is more preferably 40 mol% or more.

A polymer containing, as a monomer, an α, β-unsaturated compound containing a carboxyl group or a group convertible to the carboxyl group is usually prepared by radical polymerization. The degree of polymerization is not particularly limited.

Among the polymers thus prepared, a polymer or copolymer of acrylic acid or methacrylic acid, a copolymer of α-olefin or vinyl compound and maleic anhydride is preferable.

These polymers or copolymers are prepared by using compounds such as hydroxides, oxides or carbonates of alkali metals or alkaline earth metals such as sodium, potassium, magnesium and barium, ammonia, amines and the like. Hydrophilicity is preferably imparted by carrying out a saponification reaction. In these reactions, the polymer or the copolymer is dissolved or dispersed in various organic solvents or water, and the above-mentioned alkali metal compound, alkaline earth metal compound, ammonia, amine, etc. are added thereto with stirring. It is carried out by

Among these carboxylate type copolymers, particularly vinyl ester / (meth) acrylic acid ester copolymers, in which the hydrophilic swelling layer exhibits appropriate water swelling property, and the printing durability and ink It is preferable in that both of the resilience are satisfied.

The vinyl ester / (meth) acrylic acid ester copolymer preferably used in the present invention can be produced by a known method. Polymer Chemistry, 7
Vol. 142 (1950). That is, it is appropriately selected depending on the polymerization method, for example, initiation of polymerization of peroxides such as di-t-butyl peroxide, benzoyl peroxide, persulfates such as ammonium persulfate, and azo compounds such as azobisisobutyronitrile. It is synthesized by radical polymerization using an agent. As a polymerization method,
Solution polymerization, emulsion polymerization, suspension polymerization, etc. are required. If the amount of the (meth) acrylic acid ester component in the copolymer is small, the water absorption is small, and if it is too large, the water absorption tends to be high and the film strength tends to be extremely reduced.

Therefore, the proportion of the (meth) acrylic acid ester component in the copolymer as a starting material is generally preferably in the range of 20 to 80 mol%, which makes both water absorption and mechanical strength when water is contained. 30 for
It is preferably 70 mol%.

Examples of the vinyl ester used in the present invention include vinyl acetate, vinyl propionate and vinyl stearate. Further, as the (meth) acrylic acid ester, an alkyl ester of (meth) acrylic acid,
Specific examples include methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester and t-butyl ester.

The above-described copolymer preferably undergoes a saponification reaction in the presence of an alkali catalyst. As the solvent used for the saponification reaction, alcohol and alcohol aqueous solution are preferable. As the catalyst used in the saponification reaction, known alkali catalysts are used, but alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are particularly preferable. The saponification reaction is completed in 1 to 10 hours at 20 to 80 ° C. In the saponification reaction product of the present invention, the salt can be arbitrarily changed by a known method. Commonly used salt-forming substances include sodium hydroxide, potassium hydroxide, ammonium hydroxide, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monoethanolamine. , Diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N, N-dimethylethanolamine, N, N-
Examples thereof include dimethylisopropanolamine, cyclohexylamine, benzylamine, aniline and pyridine.

It is also possible to add polyvalent metal salts of alkaline earth metal salts such as magnesium and calcium in the form of a mixed salt with the above-mentioned salts.

It is possible to add a known hydrophilic polymer to the hydrophilic swelling layer of the present invention within a range not impairing the effects of the present invention. The following examples can be given as known hydrophilic polymers.

(A) Natural polymers Starch-acrylonitrile graft polymer hydrolyzate, starch-acrylic acid graft polymer, starch-styrene sulfonic acid graft polymer, starch-
Vinyl sulfonic acid type graft polymer, starch-acrylamide type graft polymer, carboxylated methyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, cellulose xanthate, cellulose-acrylonitrile type graft polymer, cellulose-styrene sulfonic acid type graft polymer , Carboxymethyl cellulose cross-linked product,
Hyaluronic acid, agarose, collagen, milk casein, acid casein, rennet casein, ammonia casein, potash casein, borax casein, glue, gelatin, gluten, soy protein, alginate, ammonium alginate, potassium alginate, sodium alginate arabia gum , Tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss,
Soy lecithin, pectic acid, starch, carboxylated starch, agar, dextrin, mannan, etc.

(B) Synthetic Polymers Polyvinyl alcohol, polyethylene oxide, poly (ethylene oxide-co-propylene oxide), aqueous urethane resin, water-soluble polyester, hydroxyethyl (meth) acrylate polymer (in the following description, ) □□□□ means □□□□ or meta □□□□
Is an abbreviation. ), Poly (vinyl methyl ether)
-co-maleic anhydride), maleic anhydride-based copolymers, vinylpyrrolidone-based copolymers, polyethylene glycol di (meth) acrylate-based cross-linked polymers, polypropylene glycol di (meth) acrylate-based cross-linked polymers and the like.

The above-mentioned hydrophilic polymers may be one or two monomers or copolymer components having different substituents for the purpose of imparting flexibility or controlling hydrophilicity, within the range that does not impair the effects of the invention. It is possible to appropriately mix and use one or more species.

Next, the hydrophobic polymer used in the hydrophilic swelling layer of the present invention will be described.

As the hydrophobic polymer used in the present invention, those mainly composed of an aqueous emulsion are preferably used.

The aqueous emulsion referred to in the present invention means a hydrophobic polymer suspension aqueous solution in which fine polymer particles and, if necessary, particles comprising a protective layer surrounding the particles are dispersed in water.

That is, it means a self-emulsification or forced emulsification aqueous solution which is basically composed of emulsion particles composed of polymer particles as a dispersoid and a protective layer formed as necessary, and a dilute aqueous solution as a dispersion medium. Specific examples of the aqueous emulsion used in the present invention include vinyl polymer latex, conjugated diene polymer latex and aqueous or water dispersed polyurethane resin.

Examples of the vinyl polymer type latex include acrylic type, vinyl acetate type and vinylidene chloride type. As the conjugated diene polymer latex, styrene / butadiene system (hereinafter abbreviated as SB system), acrylonitrile / butadiene system (hereinafter abbreviated as NB system), methyl methacrylate / butadiene system (hereinafter abbreviated as MB system),
Examples include chloroprene type.

Examples of the acrylic latex include copolymers containing acrylic acid ester and methacrylic acid ester as essential components. Specific examples thereof include those obtained by copolymerizing at least one kind of methyl methacrylate, ethyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, styrene and the like.

Examples of the vinyl acetate latex include vinyl acetate alone or copolymers with acrylic acid ester, higher vinyl acetate, ethylene and the like.

Examples of the vinylidene chloride latex include copolymers of vinylidene chloride and methyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, acrylonitrile, vinyl chloride and the like.

As the SB type latex, styrene and butadiene as essential components, methyl methacrylate,
Examples thereof include higher acrylic acid esters, acrylonitrile, acrylamide, hydroxyethyl acrylate, and copolymers with unsaturated carboxylic acids (itaconic acid, maleic acid, acrylic acid, methacrylic acid, etc.).

As the water-based or water-dispersed polyurethane resin, a hydrophobic polyurethane resin composed of polyester polyol, polyether polyol, poly (ester / ether) polyol and polyisocyanate is compulsorily emulsified by using a surfactant. Emulsion type, a hydrophilic group or a hydrophilic segment is added to the resin itself, and self-emulsifying type obtained by self-dispersing and emulsifying. In both cases, a non-reactive one and a blocking group such as an isocyanate group are reactive groups. The reactive ones that are blocked are mentioned.

Among these aqueous emulsions, SB is particularly preferable as the hydrophobic polymer used in the present invention.
Examples of the latex include conjugated diene-based compounds such as system-based, NB-based, MB-based, and chloroprene-based compounds.

As the conjugated diene rubber referred to here,
1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene (chloroprene)
Etc. means a compound having an unsubstituted or substituted 1,3-butadiene skeleton having a carbon-carbon double bond at the 1,3-position, and examples thereof include a homo- or block copolymer rubber (polymer) having these as an essential component. .

The block copolymer rubbers include 1,3-dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene), and styrene and α-methyl which give glassy polymers at room temperature. Examples thereof include block copolymers with monovinyl-substituted aromatic compounds such as styrene and vinyltoluene.

As such a copolymer rubber, various known types can be exemplified, but an ABA type block copolymer rubber (where A is a monovinyl-substituted aromatic compound, preferably a glass transition) is used. An amorphous polymer segment having a point of 70 ° C. or higher and a degree of polymerization of 10 to 2500, B means 1,3-diene, and preferably a number average molecular weight of 500 to 25,000. (Meaning) and the like. The same applies to hydrogenated products of the block copolymer rubber.

Specific examples of the homo- and copolymer rubbers used in the present invention include polybutadiene, polyisoprene (including natural rubber), polychloroprene, styrene-butadiene copolymer, carboxy-modified styrene-butadiene copolymer and acrylic. Acid ester-butadiene copolymer (for example, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer), methacrylic acid ester-butadiene copolymer, isobutylene-isoprene copolymer, acrylonitrile-butadiene copolymer Polymer, carboxy-modified acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, vinylpyridine-butadiene copolymer, vinylpyridine-styrene-butadiene copolymer,
Examples thereof include a styrene-chloroprene copolymer and a styrene-isoprene copolymer.

The conjugated diene polymer type latex preferably used in the present invention is prepared by a known method, for example, 0.1 to 20% by weight of an emulsion polymerization dispersant based on a vinyl monomer composition containing a conjugated diene type compound as an essential component. Additives (molecular weight modifiers, antioxidants) used for ordinary emulsion polymerization by degassing and nitrogen-substituting in an aqueous medium containing (surfactant etc.) and 2 to 50% by weight of water and emulsifying. Etc.) and then an initiator for emulsion polymerization (for example, hydrogen peroxide, potassium persulfate, etc.) is added, and emulsion polymerization is carried out according to a conventional method.

The vinyl monomer used in the raw material vinyl monomer composition other than the conjugated diene compound is not particularly limited, but mainly the following Group I: hydrophobic monomer, II.
Group: Hydrophilic monomers, Group III: Crosslinkable monomers can be classified into three groups.

Group I: As the hydrophobic monomer, a hydrophobic vinyl monomer having one vinyl group (hydrophobicity as used herein means that the solubility in water at 20 ° C. is 8% by weight or less), and acrylic Examples thereof include acid esters, methacrylic acid esters, vinyl esters, styrenes and olefins.

Specific examples of acrylic acid esters include:
Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, 2-phenoxyethyl acrylate, 2
-Chloroethyl acrylate, benzyl acrylate,
Examples thereof include cyclohexyl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate.

Specific examples of the methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n
-Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, acetoacetoxyethyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, furfuryl methacrylate, tetrahydrofur Furyl methacrylate, phenyl methacrylate, trimethylolpropane monomethacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate and the like can be mentioned.

Specific examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl acetoacetate, vinyl benzoate, vinyl salicylate, and chlorobenzoic acid. Examples thereof include vinylate.

Specific examples of styrenes include styrene,
Examples thereof include α-methylstyrene, chloromethylstyrene, trifluoromethylstyrene, acetoxymethylstyrene, methoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene and bromostyrene.

Specific examples of olefins include propylene, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide and vinylidene fluoride.

Other examples include acrylonitrile and maleic anhydride.

Group II: The hydrophilic monomer is a hydrophilic vinyl monomer having one vinyl group, and the term "hydrophilic" as used herein means a monomer having a large solubility in water and incapable of aqueous emulsion polymerization by itself. Monomers having functional groups such as amino groups, carboxyl groups, sulfonic acid groups, amide groups, and hydroxyl groups.

Specific examples of the monomer having an amino group include dimethylaminomethyl acrylate, dimethylaminomethyl methacrylate, diethylaminomethyl acrylate, diethylaminomethyl methacrylate and ter.
Examples thereof include t-butylaminoethyl acrylate and tert-butylaminoethyl methacrylate.

Specific examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, fumaric acid, methylenemalonic acid, monoalkyl itaconate (for example, monomethyl itaconate,
Monoethyl itaconate, monobutyl itaconate, etc.),
Examples thereof include monoalkyl maleate (eg, monomethyl maleate, monoethyl maleate, monobutyl maleate), citraconic acid, sodium acrylate, ammonium acrylate, ammonium methacrylate and the like.

Specific examples of the monomer having a sulfonic group include styrene sulfonic acid, vinylbenzyl sulfonic acid, vinyl sulfonic acid, vinyl sulfonic acid, acryloyloxyalkyl sulfonic acid (eg acryloyloxymethyl sulfonic acid, acryloyloxypropyl sulfonic acid, Acryloyloxybutyl sulfonic acid, etc.), methacryloyloxyalkyl sulfonic acid (eg, methacryloyloxymethyl sulfonic acid, methacryloyloxymethyl sulfonic acid, methacryloyloxypropyl sulfonic acid, methacryloyloxybutyl sulfonic acid, etc.), acrylamidoalkyl sulfonic acid (eg, 2-acrylamido) 2-Methylethanesulfonic acid, 2-acrylamido-2-methylpropane sulfone Phosphate, 2-acrylamido-2
Methyl butane sulfonic acid, etc.), methacrylamide amido alkyl sulfonic acid (eg 2-methacrylamide-2)
-Methylethanesulfonic acid, 2-methacrylamide-
2-methylpropanesulfonic acid, 2-methacrylamido-2-methylbutanesulfonic acid, etc.).

Specific examples of the monomer having an amide group include acrylamide, methyl acrylamide and propyl acrylamide.

Specific examples of the monomer having a hydroxyl group include:
Examples thereof include allyl alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and aryl ethers of polyhydric alcohol.

Other examples include N-acryloylpiperidine, vinyl pyridine, vinyl pyropide and the like.

Group III: As the crosslinkable monomers, monomers having a reactive crosslinkable group (glycidyl group, hydroxymethylamide group, alkoxymethylamide group, acyloxymethylamide group, isocyanate group, etc.) and two or more vinyls. Mention may be made of polyfunctional monomers having groups.

Specific examples of the monomer having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, glycidyl p-vinylbenzoate, glycidyl crotonate, diglycidyl itaconate, diglycidyl maleate, diglycidyl methylene malonate, glycidyl vinyl ether, Examples thereof include allyl glycidyl ether and glycidyl-α-chloroacrylate.

Specific examples of the monomer having a hydroxymethylamide group include hydroxymethyl acrylamide,
Examples thereof include hydroxymethylmethacrylamide.

Specific examples of the monomer having an alkoxymethylamide group include methoxymethylacrylamide, methoxymethylmethacrylamide, ethoxymethylacrylamide, ethoxymethylmethacrylamide, butoxymethylacrylamide, butoxymethylmethacrylamide, and hexyloxymethylmethacrylamide. Can be mentioned.

Specific examples of the monomer having an acyloxymethylamide group include acetoxymethylacrylamide,
Examples thereof include acetoxymethylmethacrylamide and propionyloxymethylacrylamide.

Specific examples of the monomer having an isocyanate group include vinyl isocyanate and allyl isocyanate.

Specific examples of the polyfunctional monomer include divinylbenzene, polyethylene glycol diacrylate (ethylene number n = 1 to 23), polyethylene glycol dimethacrylate (ethylene number n = 1 to 23), trimethylolpropane triacrylate, triethylene. Methylolpropane trimethacrylate, pentaerythritol triacrylate and the like can be mentioned.

Suitable monomer combinations for preparing the latex preferably used in the present invention include (1) a copolymer of at least one type I monomer in addition to the conjugated diene compound which is an essential component. (2) Copolymer with at least one or more group I monomers and at least one or more group II monomers (3) At least one or more group I monomers and at least one or more group II monomers and at least one or more II
Copolymers with Group I Monomers (4) Combinations of at least one or more Group I monomers and copolymers of Group III monomers and the like can be mentioned, but the present invention is not limited to these combinations.

Specific examples of the conjugated diene polymer-based latex preferably used in the present invention include JSR0561.
(SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), J
SR0589 (SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0602 (SB copolymer latex:
Japan Synthetic Rubber Co., Ltd.), JSR0700 (butadiene polymerized latex: Japan Synthetic Rubber Co., Ltd.), JSR21
08 (SB copolymer latex: Nippon Synthetic Rubber Co., Ltd.)
Manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0650 (vinyl pyridine-SB copolymer latex).
(Vinyl pyridine-SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0545 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR05
48 (carboxy modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0596 (carboxy modified SB
Copolymerized latex: manufactured by Nippon Synthetic Rubber Co., Ltd., JSR0
597 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0598 (carboxy modified S
B copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd., JSR
0619 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0624 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JS
R0640 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0693 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), J
SR0696 (carboxy modified SB copolymer latex:
Manufactured by Nippon Synthetic Rubber Co., Ltd., JSR0854 (carboxy modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.),
JSR0863 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR0898 (carboxy modified SB copolymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.)
LACSTAR 4940B (carboxy modified NB copolymer latex: Dainippon Ink and Chemicals Incorporated), LAC STAR 68-073S (carboxy modified NB copolymer latex: Dainippon Ink and Chemicals Incorporated), rack Star DN-704 (carboxy modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Luck Star DN-702 (carboxy modified NB copolymer latex:
Dainippon Ink and Chemicals, Inc., Rack Star 68-
074 (carboxy modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Rack Star DN-703
(Carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Rackstar DM-801 (carboxy modified MB copolymerized latex: manufactured by Dainippon Ink and Chemicals, Inc.), Rackstar DM-401 (Carboxy) Modified MB copolymer latex: Dainippon Ink and Chemicals, Inc., LACSTAR 4950C (carboxy modified MB copolymer latex: Dainippon Ink and Chemicals, Inc.)
), Rackstar DM-806 (carboxy modified MB
Copolymerized latex: Dainippon Ink and Chemicals, Inc. and the like can be mentioned.

These conjugated diene polymer latexes can be used alone or in admixture of two or more.

The hydrophilic swelling layer of the present invention is formed on the substrate by mixing the above-mentioned hydrophilic polymer and hydrophobic polymer, crosslinking or pseudo-crosslinking them if necessary, and insolubilizing them in water.

For cross-linking, it is preferable to carry out the cross-linking reaction using the reactive functional groups of the hydrophilic polymer and the hydrophobic polymer.

The crosslinking reaction may be covalent crosslinking or ionic bonding crosslinking.

Examples of the compound used in the crosslinking reaction include known polyfunctional compounds having a crosslinking property, such as polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilyl compounds, Polyvalent metal salt compounds, polyamine compounds, aldehyde compounds, polyvinyl compounds, hydrazine and the like can be mentioned. The crosslinking reaction is carried out by adding a known catalyst,
A reaction is promoted.

When an aqueous emulsion preferably used as the hydrophobic polymer of the present invention is prepared, a reactive functional group such as a carboxyl group, a hydroxyl group, a methylolamide group, an epoxy group, an arbonyl group or an amino group is used as a copolymerization component. And a method of forming a crosslinked structure by using the above polyfunctional compound as a crosslinking agent.

The following compounds may be mentioned as specific examples of known polyfunctional compounds having crosslinkability.

(1) Sublimation sulfur, by-product sulfur produced by oxidizing hydrogen sulfide, colloidal sulfur produced by wet-oxidizing hydrogen sulfide, and the like. In addition, thiuram compounds such as dithiomorpholine, thioplast tetramethyl thiuram disulfide, tetramethyl thiuram monosulfide, dipentamethylene thiuram tetrasulfide, which decompose to generate sulfur when heated, piperidine pentamethylene thiocarbamate, pipecoline pipecolic Dithiocarbamate compounds such as ludithiocarbamate and sodium dimethyldithiocarbamate, xanthate compounds such as sodium isopropylxanthogenate and zinc butylxanthate, thiourea compounds such as thiourea and thiocarbanilide, zinc salts of thiazole such as diphenylguanidine, and mercaptobenzothiazole Sodium salt, dibenzothiazyl disulfide, cyclohexylamine salt of mercaptobenzothiazole Such as thiazole-based compound.

(2) Butyraldehyde-monobutylamine condensate, butyraldehyde-aniline condensate, heptaaldehyde-aniline reaction product, salt ethyl-formaldehyde-ammonia reaction product, and other aldehyde amine compounds, zinc oxide, tellurium, selenium, Zirconium carbonate ammonia, organic peroxides such as benzoyl peroxide and dicumyl peroxide.

Further, examples of the crosslinking accelerator include zinc carbonate, stearic acid, oleic acid, lauric acid, zinc stearate, dibutylammonium oleate, diethanolamine, triethanolamine, diethylene glycol and the like.

(3) Polyepoxy compounds, urea resins, polyamines, melamine resins, benzoguanamine resins, acid anhydrides, etc.

Specific examples of the polyepoxy compound include glycerin dipolylysidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether and the like. Is mentioned.

Specific examples of the polyamine include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine,
Examples thereof include polyamidoamine.

(4) Polyisocyanate compounds and the like.

Examples of polyisocyanate compounds include:
Tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane isocyanate, liquid diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, xylylene diisocyanate, cyclohexyl diisocyanate, cyclohexanephenylene diisocyanate, naphthalene-1,5-diisocyanate, isopropylbenzene-2,4-diisocyanate, polypropylene Examples include glycol / tolylene diisocyanate addition reaction products.

These cross-linking agents may be used alone or in admixture of two or more. Water is mainly used as the dispersion medium, but a known organic solvent can be added if necessary. The organic solvent may be added as a polymerization solvent or as a mixed solvent to the emulsion solution after emulsion polymerization.

As a method for mixing the hydrophilic polymer and the hydrophobic polymer of the hydrophilic swelling layer of the present invention, a kneading method using a mixer such as a roll mixer with three rolls, a kneader, a homogenizer, a ball mill, etc. The mixing is preferably carried out by a known method used for producing a paint or putty, such as a method of wet mixing and dispersing using a disperser.

As a method for forming the hydrophilic swelling layer of the present invention, since an aqueous emulsion is preferably used as the hydrophobic polymer, each component (hydrophilic polymer, hydrophobic polymer, etc.) is mixed in an aqueous solution system, A method in which a crosslinking agent is added as necessary is preferable from the viewpoint of realizing a uniform phase-separated structure and improving ink repulsion.

Therefore, it is particularly preferable to use a water-soluble polyfunctional compound as the crosslinking agent used. That is, it is preferable to use a water-soluble polyepoxy compound, polyamine compound, melamine compound, or the like.

Next, the phase separation structure of the hydrophilic swelling layer according to the present invention will be described.

By adopting a phase-separated structure composed of a phase containing a hydrophilic polymer as a main component and a phase containing a hydrophobic polymer as a main component, both ink repellency and printing durability are realized in a wide composition range. It becomes possible.

The composition ratio of the hydrophilic polymer phase and the hydrophobic polymer phase constituting the phase-separated structure is free, and (1) either one is a continuous phase and the other is a dispersed phase, (2) hydrophilic Form in which the hydrophilic and hydrophobic polymer phases have a continuous phase and a dispersed phase, respectively (3) The hydrophilic and hydrophobic polymer phases can both be freely selected from the forms in which they are continuous phases.

Examples of the phase separation structures (1) to (3) are shown in FIGS.

That is, when a material in which the hydrophilic polymer exhibits relatively strong hydrophilicity is selected (such as a water-soluble polymer and a pseudo-water-soluble polymer), the ratio of the hydrophilic polymer contained in the hydrophilic swelling layer is determined by the ink repulsion property. Further, from the viewpoint of printing durability, a relatively small amount is sufficient, and since the proportion of the hydrophobic polymer is relatively large, the above-mentioned form (1) or (2) in which the hydrophilic polymer is the dispersed phase is adopted. Is preferred. On the other hand, when a material in which the hydrophilic polymer exhibits relatively weak hydrophilicity is selected (such as a water-swellable polymer), the ratio of the hydrophilic polymer contained in the hydrophilic swelling layer depends on the ink resilience and printing durability. Therefore, since a relatively large amount is required and the ratio of the hydrophobic polymer is relatively small, the above (1),
The form (2) or (3) is preferable.

That is, the preferred phase separation structure of the hydrophilic swelling layer used in the present invention depends on the rubber elasticity and water swelling property of the layer, but it depends on the degree of hydrophilicity of the hydrophilic polymer.

In the case of the form (1), since the hydrophobic polymer phase is mainly a continuous phase, the composition of the hydrophobic polymer is 50% by weight or more, preferably 60 to 95% by weight, It is more preferably 70 to 90% by weight. When the composition ratio of the hydrophobic polymer is 50% by weight or less, the performance of the hydrophilic swelling layer as an ink repellent layer is improved in the early stage of printing, but the printing durability tends to be sharply reduced. On the other hand, when the composition ratio of the hydrophobic polymer exceeds 95% by weight, the hydrophilic polymer in the hydrophilic swelling layer cannot sufficiently absorb water, and the hydrophilicity is insufficient, and the ink repulsion tends to be extremely reduced.

In the cases of the forms (2) and (3), both the hydrophilic polymer and the hydrophobic polymer are 20% by weight or more, preferably 40% by weight or more.

The hydrophilic swelling layer preferably has rubber elasticity.

The rubber elasticity of the hydrophilic swelling layer is characterized by the value of the initial elastic modulus measured by the method described below.

[Method of measuring initial elastic modulus of hydrophilic swelling layer]
A solution having the same composition as the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor to be measured is spread on a Teflon dish and dried and cured at 60 ° C. for 24 hours. The obtained dried and cured film is 40 mm long and 1.95 wide using a razor blade or the like.
mm, and a thickness of about 0.2 mm.

The test piece thus obtained was measured at 25 ° C. before measurement.
After being left to stand in an environment of 50% RH for 24 hours or more to adjust the humidity, the thickness was measured with a micro gauge, and the initial elastic modulus was measured under the following tensile conditions. Data processing is JIS K6
It was carried out according to 301.

Tensile speed 200 mm / min Chuck distance 20 mm Number of repetitions 4 times Measuring machine “RTM-100” Tensilon universal testing machine (manufactured by Orientec Co., Ltd.) Hydrophilic swelling used in the photosensitive lithographic printing plate precursor of the invention. The initial elastic modulus of the layer is preferably in the range of 0.01 to 10 kgf / mm ² from the viewpoint of ink resilience and shape retention. More preferably 0.01 to 5 kgf / m
The range is m ^{2, and} the range of 0.01 to ² kgf / mm ² is more preferable.

That is, the initial elastic modulus is 0.01 kgf /
If it is less than mm ² , the shape retention of the hydrophilic swelling layer tends to be extremely lowered, and the durability during printing tends to be extremely lowered.

On the other hand, when the initial elastic modulus is more than 10 kgf / mm ² , rubber elasticity is insufficient and ink repulsion tends to be extremely lowered.

The hydrophilic swelling layer used in the present invention preferably has a water swelling rate measured according to the following definition within a specific range.

[0132]

[Equation 1] However, the water absorption amount means a value measured according to the following definition.

[0133] water absorption ^{(g / m 2) = W} WET -W DRY W DRY: Weight in dry state _{^{(g / m 2) W WET}} : Weight after immersing 25 ° C. × 10 minutes in water (g
/ M ² ) [Measurement method of water absorption amount] The photosensitive lithographic printing plate precursor to be measured is cut into a predetermined area and immersed in purified water at 25 ° C. After soaking for 10 minutes, excess water adhering to the front and back surfaces of the hydrophilic swelling layer of the original plate was quickly wiped off with "Hize Gauze" (cotton cloth: Asahi Chemical Industry Co., Ltd.),
The swelling weight W _{WET of the original} plate is weighed. Then, the original plate is dried in an oven at 60 ° C. for about 30 minutes to obtain a dry weight W
Weigh _DRY .

The hydrophilic swelling layer used in the present invention can be used at a water swelling rate of 10 to 1000%.
From the viewpoint of ink repellency and shape retention, it is preferably 50 to 500%. If the water swelling ratio is less than 10%, the ink repelling property tends to be extremely reduced, and defects such as pinholes are likely to occur during coating. Again 10
When it is more than 00%, the shape retention tends to be extremely lowered.

The hydrophilic swelling layer thickness referred to in the present invention is a value measured by a gravimetric method after peeling off the coating layer of the hydrophilic swelling layer of the dried photosensitive lithographic printing plate precursor coated on the substrate. means. The thickness of the hydrophilic swelling layer was measured according to the following formula.

Hydrophilic swelling layer thickness (g / m ² ) = (W−W ₀ ) / α W: Dry weight of photosensitive lithographic printing plate precursor (g) W ₀ : Peeling off hydrophilic swelling layer from W Dry weight after removal (g) α: Measurement area of photosensitive lithographic printing plate precursor (m ² ) [Measurement method of hydrophilic swelling layer thickness] The photosensitive lithographic printing plate precursor to be measured has a predetermined area α. After cutting, it is dried in an oven at 60 ° C. for about 30 minutes, and the dry weight W is weighed. Then, the original plate is immersed in purified water to swell the hydrophilic swelling layer, and the swelling layer is peeled off using a scraper or the like. The original plate from which the hydrophilic swelling layer was peeled off and dropped again 6
Dry in an oven at 0 ° C. for about 30 minutes and weigh dry weight W ₀ .

The thickness of the hydrophilic swelling layer used in the present invention is
Although it is possible to use 0.1 to 100 g / m ² ,
From the viewpoint of ink repellency and shape retention, it is preferably 0.3 to 10 g / m ² . The thickness is 0.3 g / m ²
When the amount is less than the range, the ink repelling property tends to be extremely reduced, and defects such as pinholes are likely to occur during coating. Further, when it is 10 g / m ² or more, the shape retention property when swollen with water tends to deteriorate, which is economically disadvantageous.

Next, the protective layer of the present invention will be described.

On the surface of the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention, a suitable protective layer is formed on the hydrophilic swelling layer by coating for the purpose of protecting the hydrophilic swelling. Laminating the film is performed. In addition, the protective layer may contain a photobleaching substance for the purpose of protecting the photosensitive layer from exposure to light (meaning that the non-irradiated portion is originally irradiated with light other than the exposure light source). it can. In the present invention, since the hydrophilic swelling layer contains a lipophilic ethylenically unsaturated compound that can be extracted and removed by washing with water or the like, it prevents transfer from the surface of the original plate due to contact with other substances, and It is preferable to form a protective phase in order to accelerate the photo-curing of the compound.

Specific examples of the protective film include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate and cellophane. Further, these protective films are subjected to unevenness treatment, surface matte treatment, or a plastic layer containing silica particles on the surface of the protective film in order to improve vacuum adhesion in a baking frame during image exposure. Coating and laminating is also preferably performed.

Next, a method for producing a lithographic printing plate using the photosensitive lithographic printing plate precursor according to the invention will be described.

The photosensitive lithographic printing plate precursor according to the present invention becomes a printing plate through a plate making process for negative working. That is, the lipophilic ethylenically unsaturated compound present in the hydrophilic swelling layer formed on the substrate is exposed through the negative original image film and the protective film located above the hydrophilic swelling layer.

The photosensitive lithographic printing plate precursor according to the invention, after exposure,
The plate making is basically completed only by peeling off the protective film and washing the plate surface with water. The water used in the washing step does not require any special additives, and it is only necessary to wash the plate surface with tap water.

From the standpoint of enhancing the efficiency of washing with water, it is free to use the rinse liquid supply and development promoting means used in known automatic developing machines such as spraying, showering, dipping, brushing and rubbing. Moreover, the temperature of the supplied water is not limited.

Further, after the washing treatment with water, it is preferable to wash with an oily solvent for the purpose of completely removing the extracted residue of the lipophilic ethylenically unsaturated compound from the plate surface.

As specific examples of the oily solvent, paraffinic hydrocarbons, isoparaffinic hydrocarbons, cycloparaffinic hydrocarbons and aromatic hydrocarbons are used alone or in a mixed form. Typical examples of these hydrocarbon solvents include petroleum fractionated products and reformed products thereof.

In the exposed area, the ethylenically unsaturated compound is photocrosslinked and fixed in the hydrophilic swelling layer. When the hydrophilic swelling layer comes into contact with water, the exposed portion has a photocrosslinking lipophilic component which inhibits the water swelling property of the hydrophilic swelling layer and reduces rubber elasticity due to an increase in crosslink density. It becomes the streak part of flesh. On the other hand, the lipophilic ethylenically unsaturated compound present in the hydrophilic swelling layer in the unexposed area is easily removed from the hydrophilic swelling layer when it swells in water when the hydrophilic swelling layer comes into contact with water. Are extracted and removed into a non-image area having a phase separation structure and water swelling property suitable for repelling ink. The lipophilic ethylenically unsaturated compound extracted from the hydrophilic swelling layer at the portion corresponding to the non-image area by the water washing step is not soluble in water, and thus is a known oil absorbing material (for example, "Toray WOSEP"). : Toray Co., Ltd., etc.) can be easily adsorbed and separated by arranging it in a drainage channel for washing water.

As described above, the photosensitive lithographic printing plate precursor according to the invention has a rubber having a phase separation structure of an ink repellent hydrophilic swelling layer due to a photoreaction of a lipophilic ethylenically unsaturated compound of a photosensitive compound. An image is formed by forming a lipophilic image part that changes elasticity and water swelling property.

Examples of the light source used in the plate-making exposure process of the present invention include a high pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, and a fluorescent lamp.

The substrate of the photosensitive lithographic printing plate precursor used in the invention is not limited except that it is required to have flexibility which can be attached to an ordinary lithographic printing machine and load which can be applied during printing. Absent.

Typical examples are aluminum, copper, iron,
Examples thereof include a metal plate, a plastic film such as a polyester film and a polypropylene film, coated paper, and a rubber sheet. Further, the substrate may be a composite of the above materials.

Further, the surface of the substrate may be subjected to various surface treatments such as electrochemical treatment, acid-base treatment and corona discharge treatment for the purpose of improving plate inspection property and adhesiveness.

It is also possible to form a primer layer on these substrates by coating or the like for the purpose of improving the adhesiveness and preventing halation, to obtain substrates.

Next, a printing method using a printing plate prepared from the photosensitive lithographic printing plate precursor according to the invention will be described.

A known lithographic printing machine is used for the lithographic printing of the present invention. That is, an offset and direct printing type sheet-fed and rotary printing machine is used.

After the photosensitive lithographic printing plate precursor of the invention is image-formed, it is mounted on the plate cylinder of these lithographic printing machines, and ink is supplied to the plate surface from an inking roller which comes into contact therewith. The non-image area having the hydrophilic swelling layer on the plate surface swells with the dampening water supplied from the dampening water supply device to repel the ink. On the other hand, the image area receives the ink and supplies the ink to the surface of the offset blanket cylinder or the surface of the printing medium to form a printed image.

The fountain solution used when printing with the printing plate obtained from the photosensitive lithographic printing plate precursor according to the invention is PS with water.
It is of course possible to use the etchant used in the plate, but it is also possible to use pure water containing no additives.

When printing using the photosensitive lithographic printing plate of the present invention, it is preferable to use pure water containing no additives.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0160]

【Example】

Examples 1-14 A 0.2 mm thick aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) was coated with the following composition and then heat-treated at 150 ° C. for 60 minutes to have hydrophilic swelling having a thickness of ² g / m ^2. The layers were applied.

<Hydrophilic swelling layer composition (parts by weight)> (1) Hydrophilic polymer 18 parts by weight (2) Tetraethylene glycol diglycidyl ether 5 parts by weight (3) Aqueous latex "JSR0596" 75 parts by weight [carboxy-modified styrene -Butadiene copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc. (4) 2-Aminopropyltrimethoxysilane 2 parts by weight (5) Purified water 900 parts by weight [Synthesis example of hydrophilic polymer] 60 g vinyl acetate and acrylic A mixture of 40 g of acid and 0.5 g of benzoyl peroxide as a polymerization initiator was dispersed in 300 ml of water containing 3 g of partially saponified polyvinyl alcohol as a dispersion stabilizer and 10 g of NaCl.

The dispersion was stirred at 65 ° C. for 6 hours to carry out suspension polymerization. The methyl acrylate component of the obtained copolymer was 48 mol% as a result of identification from the NMR spectrum. The intrinsic viscosity in a benzene solution at 30 ° C was 2.10.

Then, 8.6 g of the copolymer was added to a saponification reaction liquid consisting of 200 g of methanol, 10 g of water and 40 ml of 5 parts of NaOH, and the suspension was stirred and suspended at 25 ° C.
After performing the saponification reaction for 1 hour, the temperature was raised to 65 ° C., and the saponification reaction was further performed for 5 hours.

The obtained saponification reaction product was thoroughly washed with methanol and freeze-dried. The saponification degree is 98.3 mol%, and the result of measurement of infrared absorption spectrum is 1570 cm.
A strong absorption attributed to the —COO ⁻ group at ⁻¹ was confirmed.

On the hydrophilic swelling layer coated as described above, the photosensitive composition having the composition shown in Table 1 below was applied, and 1
Photosensitive composition 0.5 g / m ^{2 after} heat treatment at 00 ° C for 3 minutes
Was impregnated into the hydrophilic swelling layer.

Thereafter, a 12-micron-thick single-sided matted biaxially oriented polypropylene film was laminated with a calendar roller so that the non-matted surface was in contact with the hydrophilic swelling layer, and a negative type lithographic printing plate precursor was laminated. Got

The lithographic printing plate obtained was a PCW (PLATE CONTOROL WEDGE: manufactured by KALLE) using a high pressure mercury lamp "Jetlight 3303 kW: manufactured by Oak Manufacturing Co., Ltd."
Contact exposure for 90 seconds through a negative film (3.
6 mW / cm ² ). Next, rinse the entire plate with tap water,
The photosensitive composition in the unexposed area was washed to obtain a printing plate.

After swelling the hydrophilic swelling layer corresponding to the ink repellent portion of the printing plate obtained in Example 3 with water, OsO ₄
It was stained and observed by TEM (transmission electron microscope).

As a result of the observation, the hydrophilic swelling layer had a phase-separated structure composed of a phase containing a hydrophilic polymer as a main component and a phase containing a hydrophobic polymer as a main component as shown in FIG. confirmed. In addition, it was confirmed that the photopolymerized lipophilic monomer was fixed in the image area to inhibit water swelling.

(1) 20 parts by weight of monomers shown in Table 1 (2) 2 parts by weight of Michler's ketone (3) 2 parts by weight of 2,4-diethylthioxanthone (4) “Isopar E” (isoparaffin hydrocarbon: esso Chemical Co., Ltd.) 76 parts by weight

[Table 1] The obtained printing plate is a sheet-fed offset printing machine "Sprint 2".
5: made by Komori Corporation ",
While supplying commercially available purified water as fountain solution, fine paper (62.5
(kg / chrysanthemum). The ink repellency and ink receptivity were evaluated by visually observing the printed matter. The initial elastic modulus and the water swelling ratio of the image area and the non-image area were measured according to the definitions. Table 2 shows the evaluation results.

[0171]

[Table 2] As described above, the rubber elasticity (initial elastic modulus) and water swelling rate of the hydrophilic swelling layer in the portion corresponding to the non-image area are all the same as those of the blank (only the hydrophilic swelling layer was measured for rubber elasticity and water swelling rate). Thus, it was confirmed that the lipophilic ethylenically unsaturated compound was completely extracted and removed.

At the time of printing about 1000 sheets, ink stains did not occur on each printing plate, and clear printed matter having sufficient contrast was obtained.

Example 15 The planographic printing plate used in Example 1 and an ordinary PS plate (FPQ;
A plate obtained by exposing and developing Fuji Photo Film Co., Ltd. to a printing plate was mounted on the same plate cylinder, and printing was performed in the same manner as in Example 1 while supplying commercially available purified water as dampening water. went.

When the supply amount of dampening water was increased from the standard condition, the ink density in the image area was drastically reduced in the area where the PS plate was used, resulting in so-called "water loss" and poor ink replenishment. did. On the other hand, in the portion where the planographic printing plate used in Example 1 was used, the degree of inking failure was slight.

When the amount of dampening water supplied was reduced from the standard conditions, ink stains were generated on the entire surface of the portion using the PS plate. On the other hand, good printed matter was obtained in the area where the planographic printing plate used in Example 1 was used.

[0176]

Since the photosensitive lithographic printing plate precursor according to the invention uses a lipophilic ethylenically unsaturated compound as a photosensitive component, it is excellent in the ink receptivity of the image area and can be basically washed by washing the plate surface with water. Plate making

The lithographic printing plate obtained from the original plate exhibits a high ink repellent property without any special surface treatment on the substrate which is necessary for the conventional PS plate to develop an ink repellent property. Further, the ink can be repelled efficiently with a small amount of dampening water supply, and the control range of dampening water is expanded. Further, printing can be performed without using a solvent such as isopropanol which is usually added to the fountain solution.

[Brief description of drawings]

FIG. 1 shows an example of a phase separation structure of a hydrophilic swelling layer of a photosensitive lithographic printing plate precursor according to the invention.

FIG. 2 shows an example of the phase separation structure of the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention.

FIG. 3 shows an example of the phase separation structure of the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention.

Claims (5)

[Claims] 1. A photosensitive lithographic printing plate precursor comprising at least a photosensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer contains a lipophilic ethylenically unsaturated compound. Photosensitive lithographic printing plate precursor. 2. The hydrophilic swelling layer has a phase-separated structure composed of at least two phases, a phase containing a hydrophilic polymer as a main component and a phase containing a hydrophobic polymer as a main component. 1. The photosensitive lithographic printing plate precursor as described in 1. 3. The photosensitive lithographic printing plate precursor according to claim 1, further comprising a protective layer on the hydrophilic swelling layer. 4. The surface of the photosensitive lithographic printing plate precursor according to claim 1 is irradiated with an actinic ray to expose a lipophilic ethylenically unsaturated compound in a hydrophilic swelling layer in a portion corresponding to an image area. A method for producing a lithographic printing plate, which comprises curing and then removing the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer in the portion corresponding to the non-image area. 5. The method according to claim 4, wherein the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer corresponding to the non-image area is removed by washing the entire surface of the plate with water. For producing a lithographic printing plate.