JP2000162764A - Photosensitive material for positive lithographic printing plate and method for forming printing plate by using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the photosensitive material for the positive lithographic printing plate and the method for forming the printing plate, by using it, having printing resistance after burning treatment good burning treatment efficiency. SOLUTION: The photosensitive material for the priting plate is manufactured by forming a photosensitive layer containing at least a novolak type phenol resin and/or a polyvinylphenol resin, an o-quinone diazide compounds, and a silica gel on a support having a hydrophilic surface. The novolak resin is embodied by polycondensing at least one kind of phenols, such as phenol, m-, o-, or p-cresol or the like with at least one kind of aldehyde, such as formaldehyde, paraformaldehyde, and acetaldehyde, and the novolak resin to be used has a weight average molecular weight of 1,000-15,000, preferably, 1,500-10,000 in terms of that of polystyrene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithographic printing plate used in the field of offset printing, and more particularly to a positive lithographic printing plate precursor having improved burning characteristics and a method for producing a printing plate using the same.

[0002]

2. Description of the Related Art A method of manufacturing a printing plate by exposing a positive photosensitive lithographic printing plate using actinic rays, performing a developing process, and further performing a heating process (hereinafter, referred to as a burning process) is described below. For example, British Patent No. 1,151,199
No. 1,154,749. The burning treatment is usually performed by heating at 180 to 320 ° C. for 1 to 60 minutes. By this processing, the image area is hardened, and the printing durability is significantly improved.

As a method of improving printing durability by a burning process, there is a technique in which a printing plate is previously treated with a specific processing solution and then a burning process is performed.
-52,057, 55-52,061, 60-
138,551, 60-138,552, 61
JP-A-151,658, JP-A-62-264,053, JP-A-1-161,350 and JP-A-9-265,190, etc., but the effect of the processing solution is certainly the plate after burning. Although it has the advantage of being clear and hardly causing print stains, it has not been satisfactory in terms of improving printing durability.

As another method, a printing plate in which a specific organic compound or a high molecular compound is added to a photosensitive layer is subjected to a burning treatment.
No. 63-276,047, JP-A-6-1022.6.
No. 71, No. 6-282,067, No. 7-64,285
Nos. 7-333, 839, etc., although the printing durability is improved by the action of these additives, they are satisfactory because of problems such as a decrease in sensitivity, a decrease in developability, and a deterioration in storage stability. Was not.

On the other hand, when performing the burning treatment for a long time at a high temperature, the crystal phase of the aluminum metal plate used as the substrate changes, and it is said that the aluminum plate becomes stiff and cannot be used as a printing plate. There is a problem, and a method that can efficiently perform the burning process in a shorter time has been desired.

On the other hand, as an example of using an inorganic material such as colloidal silica or silica sol for a lithographic printing plate, for example,
JP-A Nos. 61-255,899 and 61-286,20
Nos. 0, 61-290, 097, 62-1, 587
Nos. 62-44,498 and 62-50,194
No. 62-60,695, etc., as an inorganic treatment base material for a hydrophilic layer of a direct drawing type lithographic printing plate precursor, or disclosed in JP-A Nos. 2-23,347, 2-23, 34
No. 8, No. 2-190, 393, No. 2-212, 845
Nos., 6-234, 284, 6-316, 182
Nos. 6-316,183 and 8-107,092
No., 8-240,914, 9- 211,843
No. 10-311, 311 and the like, and has been exclusively used as a treatment base material in a surface hydrophilic treatment layer of a lithographic printing plate support. Therefore, there has been no known case in which these colloidal silicas or silica sols are used by being added to a photosensitive layer.

However, silica powder and fine particles are added to the photosensitive layer of a lithographic printing plate.
No. 104, No. 55-76,351, No. 56-60,4
As disclosed in JP-A No. 32, JP-A-5-72,723 and the like, improvement in the film strength and abrasion resistance of the photosensitive layer has been attempted. However, the addition of these fine powders and fine particles to the photosensitive layer is difficult to uniformly add to the photosensitive layer due to a difference in specific gravity from other compositions, and fine particles eluted during development may cause precipitation or residue. As a result, it remains in the developing tank and contaminates the printing plate, and causes problems such as clogging of pipes.

[0008]

That is, the first problem to be solved by the present invention is that a photosensitive layer for a positive type lithographic printing plate comprises silica sol as an inorganic material and an organic photosensitive composition. It is an object of the present invention to provide a positive-working lithographic printing plate precursor comprising a stable composite. A second object of the present invention is to provide a positive type lithographic printing plate precursor in which the printing durability accompanying the burning process is excellent. A third object of the present invention is to provide a method for producing a printing plate having good burning efficiency using the positive type lithographic printing plate precursor according to the present invention.

[0009]

The present inventors say that silica sol as an inorganic material is uniformly dispersed in a photosensitive layer for a positive type lithographic printing plate to form a stable composite of an organic material and an inorganic material. Gain new insights, and in this case,
Since the particle size of the silica sol used is as small as 10 to 30 nm, it was found that a positive type lithographic printing plate precursor having excellent burning characteristics due to the heat treatment was obtained without causing the above-described residual during development and causing trouble. This has led to the invention.

That is, a first constitution of the present invention is that at least (a) a resin comprising a novolak type phenol resin and / or a polyvinyl phenol resin, and (b) an o-quinonediazide compound on a support having a hydrophilic surface. And (c) a photosensitive lithographic printing plate precursor comprising a photosensitive layer containing silica sol. In addition, the second configuration of the present invention is a process of forming a printing plate image by using the above-described master plate, bringing a positive image film into close contact, exposing the entire surface with actinic rays, and developing with an alkaline developer. This is a method for producing a printing plate by passing through post-treatment steps of washing, gumming and drying. Further, a third configuration is a printing plate manufacturing method including a step of performing a burning process on the obtained printing plate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the photosensitive layer of the positive type lithographic printing plate precursor according to the invention,
(A) A resin composed of a novolak type phenol resin and / or a polyvinyl phenol resin is used. Novolak resins include phenol, m-cresol, o-
Cresol, p-cresol, 2,5-xylenol,
3,5-xylenol, resorcinol, pyrogallol, bisphenol, bisphenol-A, trisphenol, o-ethylphenol, m-ethylphenol, p
-Ethylphenol, propylphenol, n-butylphenol, t-butylphenol, 1-naphthol,
At least one kind of aromatic hydrocarbons such as 2-naphthol is subjected to an acidic catalyst, and aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, paraaldehyde, propionaldehyde, benzaldehyde, and furfural, and acetone, methyl ethyl ketone, methyl isobutyl ketone and the like. At least one selected from ketones
And those polycondensed with various aldehydes or ketones.

Preferred aromatic hydrocarbons of the novolak resin include phenol, m-cresol, o-cresol, p-cresol, 2,5-xylenol, 3,5
At least one selected from xylenol and resorcinol;
Those obtained by polycondensing a kind of phenol with at least one aldehyde selected from aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, paraaldehyde and propionaldehyde are particularly preferably used.

As the molecular weight of the novolak resin, those having a weight average molecular weight in terms of polystyrene of from 1,000 to 15,000, preferably from 1,500 to 10,000 as measured by gel permeation chromatography are used.

As the polyvinyl phenol resin, o-
Hydroxystyrenes such as hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (o-hydroxyphenyl) propylene, 2- (m-hydroxyphenyl) propylene, and 2- (p-hydroxyphenyl) propylene; Two or more copolymers are included. Hydroxystyrenes have chlorine on the aromatic ring,
It may have a halogen atom such as bromine, iodine, fluorine or the like or a substituent such as a lower alkyl substituent having 1 to 4 carbon atoms. And a polyvinyl phenol resin which may have a substituent such as a lower alkyl substituent.

The polyvinyl phenol resin is usually obtained by anaerobically polymerizing hydroxystyrenes which may have a substituent alone or in combination of two or more kinds thereof in the presence of a radical polymerization initiator or a cationic polymerization initiator. Is obtained by Such polyvinylphenol resin may be partially hydrogenated. A t-butoxycarbonyl group;
A resin in which some OH groups of polyvinylphenols are protected by a pyranyl group, a furanyl group, or the like may be used. The weight average molecular weight of the polyvinyl phenol resin is 1,000 to 10
Those having a molecular weight of 0000, preferably 1,500 to 50,000 are used.

The amount of the novolak type phenol resin and / or the polyvinyl phenol resin used is 40 to 95% by weight, preferably 40 to 95% by weight, based on the total solid content of the photosensitive layer in the positive type lithographic printing plate precursor of the present invention. 60 to 90% by weight.

An o-quinonediazide compound is used as the main photosensitive material of the photosensitive layer used in the positive working lithographic printing plate precursor according to the present invention. Specific examples of the o-quinonediazide compound are described in JP-A-47-5303 and JP-A-48-63, and JP-A-47-5303.
Nos. 802, 48-63, 803, 49-38, 7
No. 01, No. 56-1,044, No. 56-1,045
No., JP-B Nos. 41-11, 222 and 43-28, 40
No.3, No.45-9,610, No.49-17,481
No. 2,797,213, US Pat. No. 3,046,1
No. 20, 3,188,210, 3,454,40
0, 3,544,323, 3,573,917
Nos. 3,674,495 and 3,785,825
No. 1,227,602 and 1,251,3
No.45, No.1,267,005, No.1,329,88
8, 1,330,932, German Patent 854,89
No. 0 and the like. For light-sensitive materials used as a light-sensitive component by combining these compounds alone or in combination,
At least the present invention can be preferably applied. These photosensitive components include o-quinonediazidocarboxylic acid esters of aromatic hydroxy compounds and o-quinonediazidesulfonic acid or o-quinonediazidecarboxylic acid amides of aromatic amino compounds, and these o-quinonediazide compounds may be used alone. And those obtained by mixing with an alkali-soluble resin and providing this mixture as a photosensitive layer.

The amount of the o-quinonediazide compound used in the positive working lithographic printing plate precursor of the present invention is 5 to 50% by weight, preferably 10 to 30% by weight based on the total solid content of the photosensitive layer. % By weight.

The photosensitive layer of the positive working lithographic printing plate precursor according to the present invention contains silica sol as an essential component. The silica sol used in the present invention is a silica sol fine particle having a particle diameter of 100 nm or less, such as colloidal silica,
In addition, upon addition to the photosensitive layer, phenomena such as gelation or coagulation and sedimentation based on the interaction of other components of the photosensitive layer, that is, a novolak type phenol resin and / or a polyvinyl phenol resin or an o-quinonediazide compound, in a coating solvent. Must not cause a problem. As such a silica sol, there is an organosilica sol stably dispersed in an organic dispersion medium, which is also commercially available, and such an organosilica sol can be suitably used as the silica sol of the present invention. As the dispersion medium at this time, various organic solvents having a low boiling point, for example, methanol, ethanol,
n-propanol, isopropanol, butanol, ethylene glycol, ethylene glycol-mono-n-propyl ether, dimethylacetamide, methyl ethyl ketone, methyl isopropyl ketone, toluene, xylene, and the like, and a mixture of two or more of these organic solvents may be used. it can. The solid content in the dispersion medium of the organosilica sol is 5 to 50% by weight.

Another method for obtaining a silica sol used in the photosensitive layer of the positive planographic printing plate precursor according to the present invention is to obtain an organosilica sol by hydrolyzing silicon alkoxide and / or its oligomer in an organic dispersion medium. is there. That is, after dissolving a necessary amount of one or more kinds of tetraalkoxylans in a suitable organic dispersion solvent, a small amount of water (equimolar to
By stirring together with (a several-fold molar amount), a solution in which silica sol is dispersed in a dispersed organic solvent can be easily obtained. Specific examples of tetraalkoxylans that can be used at this time include, for example, tetramethoxysilane,
Tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-
Examples thereof include t-butoxysilane and tetraphenoxysilane, and oligomers of dimers to 15-mers derived therefrom, and any of them can be used as a raw material of the organosilica sol used in the photosensitive layer of the present invention.

The amount of the silica sol solid used in the positive type lithographic printing plate precursor according to the present invention is 2 to 40% by weight, preferably 5 to 20% by weight based on the total solids of the photosensitive layer. .

The photosensitive layer of the lithographic printing plate precursor according to the present invention may further contain, if necessary, an alkali-soluble or swellable binder resin, an oil-soluble dye or a basic dye as a colorant, a plasticizer, Additives such as components that give printout performance, surfactants, development accelerators such as various organic acids, sensitizers such as cyclic acid anhydrides, and dissolution inhibitors such as sulfonic acid derivatives can be added.

As the support for the positive photosensitive layer,
For example, a metal plate of aluminum, zinc, copper, stainless steel, iron, etc .; a plastic film of polyethylene terephthalate, polycarbonate, polyvinyl acetal, polyethylene, etc .; A composite material provided by a technique such as vacuum deposition or lamination may be used. Of these, aluminum and an aluminum-coated composite support are particularly desirable.

The surface of the aluminum support is desirably surface-treated for the purpose of increasing water retention and improving adhesion to the photosensitive layer. For example, as the surface roughening method, a method such as a brush polishing method, a ball polishing method, electrolytic etching, chemical etching, liquid honing, sand plast and the like, and a combination thereof may be mentioned, and in particular, a surface roughening method including the use of electrolytic etching. preferable.

As the electrolytic bath used in the electrolytic etching, an aqueous solution containing an acid, an alkali or a salt thereof or an aqueous solution containing an organic solvent is used, and among these, an aqueous solution containing hydrochloric acid, nitric acid or a salt thereof is particularly used. Electrolytes are preferred. Further, the roughened aluminum plate is desmutted with an acid or alkali aqueous solution as required. The aluminum plate thus obtained is desirably subjected to anodic oxidation treatment, particularly desirably a method of treating it in a bath containing sulfuric acid or phosphoric acid.

Also, if necessary, US Pat.
066 and 3,181,461 (sodium silicate, potassium silicate), U.S. Pat. No. 2,946,638, potassium fluorozirconate treatment, U.S. Pat. 201,247, Phosphomolybdate treatment, British Patent 1,108,559
Titanate treatment, German Patent No. 1,099
No. 1,433, polyacrylic acid treatment, German Patent 1,134,093 and British Patent 1,230,447
No. 4,6,409, phosphinic acid treatment described in U.S. Pat. No. 3,307,951, JP-A-58-1983. No. 16,893 and JP-A-58-1
No. 8,291, the treatment with a salt of a hydrophilic organic polymer compound and a divalent metal, and the undercoating of a water-soluble polymer having a sulfonic acid group described in JP-A-59-101,651. After processing, JP-A-60-64,3
No. 52, and a treatment such as electrodeposition with a silicate described in U.S. Pat. No. 3,658,662.

It is also preferable to perform a sealing treatment after graining and anodic oxidation. The sealing treatment is performed by immersion in hot water and a hot aqueous solution containing an inorganic salt or an organic salt, a steam bath, or the like.

The positive type lithographic printing plate precursor of the present invention was prepared by dissolving a positive type photosensitive layer composition in an appropriate organic solvent on an aluminum substrate whose surface was hydrophilized by a known technique. Apply a silica sol-dispersed photosensitive coating solution,
It is manufactured by drying. The organic solvent used at this time is not particularly limited, but preferable examples thereof include, for example, methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene. Glycol
Mono-n-propyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethylacetamide, dimethylformamide, tetramethylurea, N-methylpyrrolidone, methylethylketone, cyclohexanone,
There are methyl isopropyl ketone, dimethoxyethane, toluene, xylene, ethyl acetate, dimethyl sulfoxide, sulfolane, gamma-butyrolactone and the like, and these solvents are used alone or as a mixture. In addition, the silica sol-dispersed photosensitive coating liquid can be prepared by gradually adding and mixing the above-mentioned organosilica sol solution with stirring to a solution prepared by dissolving a composition component other than silica sol in an organic solvent in advance.

Examples of the method of applying the coating solution to the substrate include a spin coating method, a wire bar coating method, a dip coating method, an air knife coating method, a roll coating method, a blade coating method, a curtain coating method, and a spray coating method. Can be mentioned. The positive photosensitive layer applied in this manner is 40
It is dried using a hot air drier, an infrared drier or the like for 30 seconds to 10 minutes at ~ 150 ° C.

The present invention can be applied when the amount per unit area of the photosensitive layer of the positive type lithographic printing plate precursor according to the present invention is in the range of 0.5 to 7 g / m ² .

A method for producing a printing plate using the positive type lithographic printing plate precursor of the present invention will be described.

The positive planographic printing plate precursor according to the present invention is first subjected to image exposure. Image exposure is performed by bringing a positive image film into close contact with the positive-working lithographic printing plate precursor of the present invention, and then irradiating the entire surface with actinic rays. Examples of the light source of the actinic ray used for the image exposure include a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, a carbon arc lamp, and the like. Examples of the radiation include an electron beam, an X-ray, an ion beam, and far ultraviolet rays. Examples of the high-density energy light include a helium-neon laser, an argon laser, a krypton ion laser, a helium-cadmium laser, an excimer laser, a green laser as a SHG of a YAG laser, and a blue laser as a THG of a YAG laser.

The positive-working lithographic printing plate precursor according to the present invention, which has been subjected to image exposure, is then subjected to a developing treatment with an alkaline developer containing an alkaline agent.

The alkaline developer used in the present invention includes sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, Aqueous solutions of inorganic alkali agents such as ammonium diphosphate, sodium metasilicate, sodium bicarbonate, aqueous ammonia and the like and organic alkali agents such as tetraalkylammonium hydride and the like having a concentration of 0.005 to 20 are suitable. %, Preferably 0.01 to 5% by weight. In addition, various surfactants such as anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, fluorine-based surfactants, and silicone-based surfactants may be added to the developer as required. Can also be added.

Further, if necessary, a small amount of an organic solvent may be added to the alkaline developer used in the present invention as long as the photosensitive layer of the positive PS plate is not eroded. Specific examples thereof include, for example, alcohols such as ethanol, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate, butyl levulinate, ethyl butyl ketone, methyl isobutyl ketone, Cyclohexanone, ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol, xylene, methylene dichloride, ethylene dichloride, monochlorobenzene, etc. It can be used in an amount of 5% by weight or less.

Practically, a commercially available developer for concentrated type positive working PS plates can be diluted 1 to 20 times and used as the alkaline developer of the present invention.
It is also possible to carry out development processing using a developer for both positive and negative.

The processing method for development in the present invention is as follows: a positive lithographic printing plate precursor according to the present invention, which has been subjected to image exposure, is immersed in a developing solution at a temperature of 15 to 40 ° C. for a time of 1 second to 2 minutes. It is performed by washing with water. If necessary, the surface may be lightly rubbed. The use of an automatic developing machine or the like filled with a developing solution is also effective.

The positive-working lithographic printing plate precursor of the present invention after the development is subjected to washing with water and / or treatment with an aqueous desensitizing agent. Examples of the aqueous desensitizing agent include water-soluble natural polymers such as gum arabic, dextrin, and carboxymethyl cellulose; and aqueous solutions of water-soluble synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid. According to the above, an acid, a surfactant and the like are added to these aqueous desensitizing agents. After desensitization, it is dried and used as a printing plate for printing.

The steps following development may be carried out one by one, but practically, the use of an automatic developing machine capable of performing these operations consistently makes the working process easier. preferable.

The printing plate obtained by subjecting the positive type lithographic printing plate precursor according to the present invention to the respective steps of image exposure, development, washing with water, desensitizing treatment and drying is a conventional positive printing plate containing no silica sol. Compared with a printing plate obtained by performing the same treatment on a lithographic printing plate precursor, it can be used without any problem as a completely similar printing plate.

A method of burning the above printing plate to form a printing plate will be described. . As the burning treatment method, first, the printing plate obtained by the above treatment method is washed with water to remove a rinsing liquid and a gum liquid, and then squeegeeed. Next, an appropriate amount of the surface conditioning liquid is poured onto the plate, and the entire plate is uniformly spread using a special sponge. Squeeze the sponge and wipe off any excess conditioning liquid. The surface conditioning liquid on the plate is dried in a plate dryer. 18 in the burning oven
Burning is performed for 1 minute to 30 minutes under a temperature condition of 0 ° C to 300 ° C. After the plate has cooled, the surface conditioning liquid is removed by washing with water, gummed and dried to obtain a printing plate.

The surface conditioning liquid used in the present invention is exclusively used as an aqueous solution to be treated before the burning treatment so as not to cause soiling after the burning treatment.
As its main composition, various surfactants, particularly preferably anionic surfactants and / or fluorine-based surfactants, are in the range of 0.005 to 30% by weight, and the pH is in the range of 2 to 11, preferably 3 to 10. Various acids, alkalis or salts are added to maintain. Specific preferred examples of the anionic surfactant include alkyl benzene sulfonate, alkyl diphenyl ether disulfonate,
Alkyl naphthalene sulfonate, aldehyde condensate of alkyl naphthalene sulfonic acid, sulfonic acid group-containing activator such as α-olefin sulfonate, alkyl sulfonate, lauryl sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate Sulfate-based activators such as salts can be mentioned. Specific examples of the fluorine-based surfactant include a perfluoroalkyl group-containing carboxylate,
Anionic fluorinated surfactants such as perfluoroalkyl group-containing sulfonates, perfluoroalkyl group-containing sulfates, perfluoroalkyl group-containing phosphates, perfluoroalkyl group-containing amine salts, and perfluoroalkyl group-containing quaternaries Cationic fluorine surfactants such as ammonium salts, amphoteric surfactants such as perfluoroalkyl group-containing carboxybetaines and perfluoroalkyl group-containing aminocarboxylates, perfluoroalkyl group-containing oligomers, and perfluoroalkyl group-containing Nonionic fluorine-based surfactants such as polymers and adducts of perfluoroalkyl group-containing sulfonamide polyethylene glycol can be mentioned. Examples of the acid include mineral acids such as nitric acid, sulfuric acid and phosphoric acid, citric acid, succinic acid, oxalic acid, tartaric acid, acetic acid, malic acid, phytic acid, organic phosphonic acid, p-
Examples thereof include toluenesulfonic acid and xylenesulfonic acid. Also, potassium salts, lithium salts of these acids,
Examples thereof include sodium salts, ammonium salts, and hydroxides, carbonates, and bicarbonates of alkali metals.

Furthermore, the surface conditioning liquid of the present invention contains a polymer compound having a film-forming ability, which is a natural product, a modified product of a natural product or a synthetic polymer, in an amount of 0.000% based on the total weight.
1% by weight to 3% by weight can be added. Further, a preservative, an antifoaming agent, a coloring agent and the like can be added.

The printing plate obtained by subjecting the printing plate obtained from the positive type lithographic printing plate precursor according to the present invention to a burning treatment is subjected to the same treatment as a normal positive lithographic printing plate precursor containing no silica sol. When processed under the same burning treatment conditions as compared with the printing plate obtained by applying the printing plate, a printing plate having more excellent printing durability can be obtained. When printing plates having the same printing durability are obtained, the burning process can be performed in a shorter time or at a lower temperature, that is, under a more efficient processing condition.

[0045]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Preparation of Support A 0.30 mm thick aluminum plate was grained with a nylon brush and a 400 mesh pumice water suspension, and then 20% sulfuric acid was used. Anodizing treatment was performed at a current density of 2 A / dm ² in an electrolytic solution to form an oxide film of 2.7 g / m ² , which was washed with water and dried to obtain a support. (2) Preparation of the positive type lithographic printing plate precursor 1 according to the present invention On the above support, a condensation rate of 50% with the modified polyester resin
30.0 g of a compound obtained by condensing 1,2-naphthoquinone-2-diazido-5-sulfonyl chloride, 75.0 g of a cresol-formaldehyde resin, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) −
In a photosensitive solution consisting of 0.6 g of s-triazine, 1.5 g of Oil Blue # 603 (manufactured by Orient Chemical Industries), 800.0 g of methyl cellosolve acetate, and 25.0 g of methyl ethyl ketone, an organosilica sol (MEK-ST; containing 30% of silica sol): A coating solution obtained by adding 35.0 g of Nissan Chemical Co., Ltd. while gradually stirring was added to a rod number #.
The positive-working lithographic printing plate precursor 1 of the invention was prepared by applying using a 12 wire bar and drying at 110 ° C. for 1 minute.
At this time, the weight of the dried coating film was 2.1 g / m ² . (3) Preparation of the positive type lithographic printing plate precursor Comparative Example 1 On the above-mentioned support, a condensation rate of 50% was applied to the modified polyester resin.
%, A compound obtained by condensing 1,2-naphthoquinone-2-diazido-5-sulfonyl chloride, 35.0 g of a cresol-formaldehyde resin, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl )
0.6 g of -s-triazine, 1.5 g of Oil Blue # 603 (manufactured by Orient Chemical Industries), 800.0 g of methyl cellosolve acetate, 100.0 g of methyl ethyl ketone
Was coated using a wire bar having a rod number of # 12 and dried at 110 ° C. for 1 minute to prepare a positive lithographic printing plate precursor of Comparative Example 1. At this time, the weight of the dried coating film was 2.0 g / m ² . (4) Preparation of lithographic printing plate Positive lithographic printing plate precursor 1 of the present invention obtained in (2) above
A halftone positive image film and a step wedge with a step of 0.15 were brought into close contact with each other, and exposure was performed using a 1 kW output metal halide lamp (“Idol Fin 1000” manufactured by Iwasaki Electric Co., Ltd.) provided 1 m away from the film. afterwards,
Developed with an automatic developing machine PD-912P (manufactured by Dainippon Screen) filled with developer PD1 (manufactured by Polychrome Japan) and finishing gum PF2 (manufactured by Polychrome Japan) at 30 ° C. for 12 seconds. After gumming and drying, printing plate 1 was obtained. From the positive lithographic printing plate precursor of Comparative Example 1 obtained in the above (3), a printing plate was produced according to exactly the same conditions and method as the above plate making method, and Comparative Printing Plate 1 was obtained. (5) Printing test The printing plate 1 of the present invention and the comparative printing plate 1 were mounted on a printing press RZ.
K (manufactured by Roland Corporation) and apply the ink GEOS-
G Beni N (manufactured by Dainippon Ink and Chemicals, Inc.), fountain solution 108W
(Manufactured by Dainippon Ink and Chemicals, Inc.) 1:50 dilution, paper OK
A printing test of 90,000 copies was performed using a top coat (manufactured by Oji Paper Co., Ltd.). As the evaluation items of the printed matter, halftone dots (2
%, 50%, 98%) thickening, thinning, attachment, micro line attachment, water width, stain return, ink deposition, printing, print density change, background stain, etc. Until the printing of 90,000 copies was completed, a good printed matter was obtained in both the printing plate 1 and the comparative printing plate 1 without any problem, and no significant difference was observed between the two in the printing characteristics.

Example 2 (1) Preparation of Burning Printing Plate The printing plate 1 of the present invention prepared in (4) of Example 1 was washed with water and treated with a surface-regulating liquid (UT1; manufactured by Polychrome Japan). After that, it was burned in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.) at 220 ° C. for 10 minutes, washed with water and gummed to obtain a printing plate 2. Example 1 (4)
Comparative Example Printing Plate 2 was obtained under exactly the same conditions and method except that Comparative Example Printing Plate 1 produced in was used. (2) Printing Test The printing plate 2 of the present invention and the printing plate 2 of the comparative example were used for the printing press SP.
RINT26 (manufactured by Komori Co., Ltd.), two inks, ink GEOS-G Beni N (manufactured by Dainippon Ink and Chemicals, Inc.), fountain solution 108W (manufactured by Dainippon Ink and Chemicals), 1:50 dilution, paper royal coat (Oji Paper Co., Ltd.) was used to perform a printing durability test. The printing plate number of the printing plate 2 of the invention was 260,000 copies. On the other hand, the number of printings of the comparative printing plate 2 was 180,000. When the burning treatment is performed under the same conditions, it can be seen that the printing plate of the present invention has better printing durability.

Example 3 (1) Preparation of Burning Printing Plate The printing plate 1 of the present invention prepared in (4) of Example 1 was washed with water and treated with a surface-regulating liquid (UT1; manufactured by Polychrome Japan). After that, it was burned in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.) at 230 ° C. for 6 minutes, washed with water,
The printing plate 3 was obtained by gumming. The comparative printing plate 1 prepared in (4) of Example 1 was washed with water, treated with a surface-regulating liquid (UT1; manufactured by Polychrome Japan), and then placed in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.). 230 ° C,
After burning for 10 minutes, washing with water and gumming, a printing plate 3 for comparative example was obtained. (2) Printing test The printing plate 3 of the present invention and the printing plate 3 of the comparative example were used for the printing press SP.
RINT26 (manufactured by Komori Co., Ltd.), two inks, ink GEOS-G Beni N (manufactured by Dainippon Ink and Chemicals, Inc.), fountain solution 108W (manufactured by Dainippon Ink and Chemicals), 1:50 dilution, paper royal coat (Oji Paper Co., Ltd.) was used to perform a printing durability test. The printing plate number of the printing plate 3 of the invention was 240,000 copies. On the other hand, the printing number of the comparative printing plate 3 was 230,000 copies. It can be seen that the printing plate according to the present invention only needs to be burned at 230 ° C. for 6 minutes to obtain the same number of prints, while the comparative printing plate 3 requires a processing time of 10 minutes. It can be seen that the printing plate according to the present invention is more excellent in the burning processing efficiency.

Example 4 (1) Preparation of Burning Printing Plate The printing plate 1 of the present invention prepared in (4) of Example 1 was washed with water and treated with a surface conditioning liquid (UT1; manufactured by Polychrome Japan). After that, it was burned in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.) at 240 ° C. for 5 minutes, washed with water,
The printing plate 4 was obtained by gumming. The comparative printing plate 1 prepared in (4) of Example 1 was washed with water, treated with a surface-regulating liquid (UT1; manufactured by Polychrome Japan), and then placed in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.). 240 ° C,
Burning was performed for 10 minutes, followed by washing with water and gumming to obtain a printing plate 4 for comparative example. However, the printing plate 4 of the comparative example became stiff and was no longer ready for mounting on a printing press. Therefore, the comparative printing plate 1 prepared in (4) of Example 1 was washed with water and treated with a surface-regulating liquid (UT1; manufactured by Polychrome Japan), and then placed in a burning oven (SPBO-1 type; manufactured by Koyo Chemical Co., Ltd.). At 240 ° C. for 5 minutes, washed with water and gummed to prepare a printing plate 5 for comparative example. (2) Printing test The printing plate 4 of the present invention and the printing plate 5 of the comparative example were used for the printing press SP.
RINT26 (manufactured by Komori Co., Ltd.), two inks, ink GEOS-G Beni N (manufactured by Dainippon Ink and Chemicals, Inc.), fountain solution 108W (manufactured by Dainippon Ink and Chemicals), 1:50 dilution, paper royal coat (Oji Paper Co., Ltd.) was used to perform a printing durability test. The printing plate number of the printing plate 4 of the invention was 300,000. On the other hand, the printing number of the comparative printing plate 5 was 220,000 copies. It can be seen that the printing plate according to the present invention is more excellent in printing durability and burning efficiency.

[0050]

According to the present invention, a positive lithographic printing plate precursor according to the present invention, which has a photosensitive layer made of a composite composed of an inorganic silica sol and an organic photosensitive composition, is free from any problem by ordinary plate making. A printing plate is obtained,
In the burning process, a printing plate having good burning process efficiency and excellent printing durability can be obtained.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazutoshi Haraguchi 317-1, 4-901 Naganumaharamachi, Inage-ku, Chiba-shi, Chiba F-term (reference) 2H025 AA12 AB03 AC01 AD03 BE01 CB17 CB29 CC08 FA17 FA28 FA29 2H096 AA08 BA10 BA20 CA03 EA02 GA08 GA17 HA01 HA02 JA04

Claims (3)

[Claims] 1. A support having a hydrophilic surface, comprising at least (a) a resin composed of a novolak-type phenol resin and / or a polyvinyl phenol resin, (b) an o-quinonediazide compound, and (c) a silica sol. A positive-working lithographic printing plate precursor comprising a photosensitive layer. 2. On a support having a hydrophilic surface, at least (a) a resin composed of a novolak-type phenol resin and / or a polyvinyl phenol resin, (b) an o-quinonediazide compound, and (c) a silica sol. Using a positive type lithographic printing plate precursor coated with a photosensitive layer, a positive image film is brought into close contact with the plate, and then the entire surface is exposed to actinic rays, followed by development with an alkaline developer to form a printing plate image. A printing plate manufacturing method, which includes a post-treatment step, a washing step, a gumming step, and a post-treatment step of drying. 3. The printing plate production method according to claim 2, further comprising a step of performing a burning treatment after the post-treatment step.