JPH10115929A - Original lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make is possible to manufacture a printing plate washable only with water without using an alkaline processing solution, by forming a water-soluble photosensitive layer containing a silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound, a water-soluble polymer, and fine hydrophilic particles on an ink-receptive substrate. SOLUTION: The water-soluble photosensitive layer containing silver halide, a reducing agent, the ethylenically unsaturated polymerizable compound, the water-soluble polymer, and fine hydrophilic particles, is formed on the ink receptive substrate. The ink receptive layer 2, the photosensitive layer 3, and an overcoat layer 4 are laminated on the support 1, and the ink receptive substrate is composed of the support 1 and the ink receptive layer 2 made of an ink receptive polymer, and the photosensitive layer 3 comprises the silver halide, the reducing agent, the ethylenically unsaturated polymerizable compound, and the water-soluble polymer, and the fine hydrophilic particles 5 for forming roughness on the surface of the photosensitive layer, and the overcoat layer 4 contains polyvinyl alcohol having a saponification degree of >=90%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor that can be made only by washing with water without using an alkaline processing liquid.

[0002]

2. Description of the Related Art A photosensitive material which forms a cured image by heat development using silver halide as an optical sensor is disclosed in Japanese Patent Application Laid-Open No. 61-1 / 1986.
83640 and 61-188535. These photosensitive materials have a support on which a photosensitive layer comprising a silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound and a water-soluble polymer is provided.
When the photosensitive material is exposed to light and thermally developed, the silver halide is developed to generate free radicals, whereby the ethylenically unsaturated polymerizable compound is polymerized to form a polymer image. JP-A-61-188535 describes that a photosensitive material can be used for producing a printing plate. However, in the content of the technology disclosed in the publication,
It was very difficult to produce a workable printing plate.
For lithographic printing, it is necessary to form an area having ink repellency and an area having ink receptivity on the surface of the printing plate in an image form. An image obtained from the photosensitive material disclosed in JP-A-61-188535 has insufficient ink repellency and ink receptivity, making it difficult to use it as a printing plate.

A photosensitive material suitable for producing a printing plate is described in JP-A-5-249667 and JP-A-4-191856. These light-sensitive materials comprise a curable layer containing an ethylenically unsaturated polymerizable compound and a hydrophobic polymer (preferably, a hydrophobic polymer having an acidic group and an ethylenically unsaturated group) on a support, and a silver halide. Is provided. When producing a printing plate from a photosensitive material, a support having a hydrophilic surface is used. When the photosensitive material is exposed to light and thermally developed, the silver halide is developed and free radicals are generated, whereby the polymerizable compound is polymerized or the hydrophobic polymer having an ethylenically unsaturated group is crosslinked, and the curable layer is cured. I do. Then, by removing the uncured area of the photosensitive layer and the curable layer, the hydrophilic surface of the support below the uncured area is exposed. The hydrophilic surface of the support can be imparted with a sufficient degree of ink repellency for printing by using a fountain solution. The cured area of the curable layer (the hydrophobic area due to the hydrophobic polymer) has a sufficient ink receptivity for printing. By using the photosensitive material described in each of the above publications, it has become possible to produce a practical printing plate. However, in the methods described in the above publications, an image is formed by eluting and removing the uncured portion of the curable layer with the solvent (alkaline processing solution). When an alkaline solution is used, a large amount of harmful alkaline processing waste liquid is generated in image forming processing.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate precursor capable of producing a practicable printing plate only by washing with water without using an alkaline processing liquid.

[0005]

The object of the present invention has been attained by the following lithographic printing plate precursors (1) to (3). (1) silver halide, reducing agent,
A lithographic printing plate precursor provided with a water-soluble photosensitive layer containing an ethylenically unsaturated polymerizable compound, a water-soluble polymer and hydrophilic fine particles. (2) The lithographic printing plate precursor according to (1), wherein the ink-receiving substrate is a substrate having an ink-receiving layer provided on a support. (3) The lithographic printing original plate as described in (1), wherein an overcoat layer containing a polyvinyl alcohol having a saponification degree of 90% or more is further provided on the photosensitive layer.

[0006]

The original printing plate of the present invention has a water-soluble photosensitive layer, and can be made only by washing with water without using an alkaline processing solution. Therefore, no harmful alkaline waste liquid is generated in the image forming process. In the production of a printing plate, a cured region is formed on the photosensitive layer by image exposure and heat development, and then the uncured region of the photosensitive layer is removed by washing with water, and the ink receiving substrate below the uncured region is removed. Expose. Since the printing original plate of the present invention can elute the photosensitive layer only with water, the washing step can be omitted and printing can be started after heat development. That is, at the beginning of printing, the unexposed portion of the photosensitive layer remains on the substrate, but the unexposed portion of the photosensitive layer is removed in a short time by the fountain solution used for printing.
After that, printing can be performed in the same manner as the printing plate obtained by performing the washing step. In the printing plate precursor of the invention, hydrophilic fine particles are contained in the water-soluble photosensitive layer. The hydrophilic fine particles have a water retaining action for dampening water. For this reason, it is possible to impart sufficient ink repellency to the cured region of the photosensitive layer using the dampening solution. Therefore, by using the printing original plate of the present invention, it is possible to form an image having a sufficient contrast (difference between ink repellency and ink receptivity) so that printing is possible.

[0007]

FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the printing plate precursor of the present invention. As shown in FIG.
An ink-receiving layer (2), a photosensitive layer (3) and an overcoat layer (4) are sequentially provided on a support (1). The support (1) and the ink receiving layer (2) constitute an ink receiving substrate. The ink receiving layer (2) is a layer composed of an ink receiving polymer. The photosensitive layer (3)
It contains silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound, a water-soluble polymer and hydrophilic fine particles (5).
Irregularities are formed on the surface of the photosensitive layer (3) by the hydrophilic fine particles (5). The overcoat layer (4) contains polyvinyl alcohol having a degree of saponification of 90% or more. FIG.
FIG. 2 is a schematic cross-sectional view showing a state after performing image exposure and heat development processing on a printing original plate. A latent image is formed on the silver halide by imagewise exposing the printing original plate. When the printing original plate is thermally developed after or simultaneously with the image exposure, the reducing agent is oxidized at the same time as the silver halide is developed to generate free radicals, whereby the ethylenically unsaturated polymerizable compound in the exposed area is exposed. Are polymerized, and the photosensitive layer (7) in the exposed portion is cured. In contrast, there is no change in the unexposed portion of the photosensitive layer (6).

FIG. 3 is a schematic cross-sectional view showing a state after further performing a water washing process on the printing original plate after the heat development. When the printing original plate is washed with water after the thermal development, the overcoat layer and the unexposed portion of the photosensitive layer are eluted, and a printing plate having a polymerized image (8) formed on the ink-receiving substrate is obtained.
In the unexposed area, the ink receiving layer is exposed (9). The ink receiving layer is hydrophobic. On the other hand, the polymerized image (8) is hydrophilic since only the water-soluble photosensitive layer is cured. FIG. 4 is a schematic sectional view showing a state in which printing is being performed. When printing is started, the dampening solution (1
0) adheres to the surface of the polymerized image (11). Since the polymerized image (11) contains the hydrophilic fine particles (12), it has irregularities on the surface. Due to these irregularities, the water retention of the polymerized image is high. The dampening water (10) imparts ink repellency to the polymerized image. Oily ink (14) adheres to the exposed ink receiving layer (13).

[Ink-Receptive Substrate] The ink-receptive substrate means a substrate having a sufficient degree of lipophilic surface to receive (ink) printing ink. Substrate is made using a support such as paper, synthetic paper, plastic (eg, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate) film or metal (eg, aluminum, aluminum alloy, zinc, iron, copper) plate I do. The plastic film can be used as it is as an ink receiving substrate. Other supports generally have high hydrophilicity and insufficient ink receptivity, and therefore, those provided with an ink receptive layer thereon are used as ink receptive substrates. Even when a plastic film is used, it is preferable to further provide an ink receptive layer thereon.

[0010] The ink receptive layer is a layer containing an ink receptive polymer. Examples of the ink receptive polymer include vinyl polymers (eg, polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polystyrenes, polyvinyl ethers, polyvinyl esters, poly N-vinyl heterocycle) , Polyallyl ethers, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polymethacrylonitrile, polyethylene, polypropylene), polyvinyl acetal (eg,
Polyvinyl butyral, polyvinyl formal), polyesters, polyamides, polyimides, polyurethanes, polycarbonates, phenolic resins, novolak resins, and cellulose derivatives (eg, cellulose esters, cellulose ethers). Examples of cellulose esters include triacetyl cellulose, diacetyl cellulose and cellulose acetate butyrate. Examples of cellulose ethers include ethyl cellulose. Vinyl polymers and novolak resins are particularly preferred. The molecular weight of the ink receptive polymer is 50
It is preferably in the range of 00 to 500,000. The thickness of the ink receiving layer is preferably in the range of 0.1 to 10 μm, more preferably in the range of 0.3 to 3 μm.

[Photosensitive layer] The photosensitive layer contains silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound and a water-soluble polymer. The thickness of the photosensitive layer is preferably in the range of 0.1 to 20 μm, and more preferably in the range of 0.3 to 5 μm.

[Silver halide] As silver halide,
Any grains of silver chloride, silver bromide, silver iodide, or silver chlorobromide, silver chloroiodide, silver iodobromide, silver chloroiodobromide can be used. The shape of the silver halide grains is preferably cubic or tetradecahedral, but is not limited to those having a regular crystal form, and may be those having an irregular crystal form or a complex form thereof. Anomalous crystal forms include potato, spherical, plate and plate crystal forms. In the case of tabular grains, the grain size is generally at least five times the grain thickness. There is no particular limitation on the grain size of the silver halide. Fine particles of 0.01 μm or less can also be used. On the other hand, large particles of about 10 μm can be used. With respect to grain size distribution, monodisperse grains are preferred over polydisperse emulsions. For monodisperse emulsions, see US Pat.
Nos. 628 and 3655394 and British Patent 1413.
No. 748 is described in each specification.

The crystal structure of the silver halide grains may be uniform, or the interior and exterior may have different halogen compositions. It may have a layered structure. Further, silver halides having different compositions may be joined by epitaxial joining. Further, it may be bonded to a compound other than silver halide. Examples of compounds other than silver halide include silver rhodan and lead oxide. The silver halide grains may contain salts of other elements. Examples of other elements include copper, thallium, lead, bismuth, cadmium, zinc, chalcogens (eg, sulfur, selenium, tellurium), gold and Group VIII noble metals (eg, rhodium, iridium, iron, platinum, palladium) Can be mentioned. Salts of these elements can be added during or after the formation of silver halide grains and included in the grains. Specific methods are described in U.S. Patent Nos. 1195432, 1951933, 2448860 and 26281.
Nos. 67, 2950972, 3488709, 3737313, 37372031, 42699
No. 27, and Research Disclosure (RD), Vol. 13452 (June 1975).

By adding an aqueous solution of an iridium compound to the emulsion during the preparation of the silver halide emulsion, iridium ions can be introduced into the silver halide grains. Examples of the water-soluble iridium compound include hexachloroiridium (III) and hexachloroiridium (IV). Similarly, rhodium ions may be introduced into silver halide grains by adding an aqueous solution of a rhodium compound to the emulsion. Examples of the water-soluble rhodium compound include rhodium ammonium chloride, rhodium trichloride and rhodium chloride. An iridium compound or a rhodium compound may be used by dissolving it in an aqueous solution of a halide for forming silver halide grains. Further, the aqueous solution of the iridium compound or the rhodium compound may be added before the particles are formed, or may be added during the formation of the particles. Further, it may be added during the period from grain formation to chemical sensitization treatment. It is particularly preferred to add while the particles are being formed. The iridium ion or the rhodium ion is preferably used in an amount of 10 ^{-8 to} 10 ^-3 mol, more preferably 10 ^{-7 to} 10 ^-5 mol, per 1 mol of silver halide.

Two or more kinds of silver halide grains having different halogen compositions, crystal habits and grain sizes can be used in combination. Silver halide is preferably used as an emulsion. Silver halide emulsions are described in Research Disclosure (RD) Magazine, No. 17643 (December 1978
Mon., pp. 22-23, "I. Emulsion Production (Emulsion prepa
ration and types) "and No. 18716 (19
Nov. 1979), p. 648. The silver halide emulsion is usually subjected to chemical sensitization after physical ripening. It is preferable to use silver halide grains having a relatively low fog value. Additives used in such a process are described in Research Disclosure Magazine, No. No. 17643 and the same No. 18716. Regarding chemical sensitizers, 17643 (23
Page) and No. 18716 (page 648, right column). Known additives other than those described above are also described in the above two Research Disclosures. For example, as for the sensitivity enhancer, 1871
No. 6 (right column on page 648), No. 6 No. 17643 (pages 24 to 25) and no. 1
8716 (from page 649, right column).

The silver halide emulsion is usually used after spectral sensitization. As the sensitizing dye used in the light-sensitive material, a silver halide sensitizing dye known in the photographic art can be used. Examples of sensitizing dyes include cyanine dyes,
Examples include merocyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, and hemioxonol dyes. Spectral sensitizing dyes are used to adjust the spectral sensitivity of photosensitive materials to different light source wavelengths such as various lasers (eg, semiconductor laser, helium neon laser, argon ion laser, helium cadmium laser, YAG laser) and light emitting diodes. Can also be used. For example, applying a plurality of spectral sensitizing dyes having different spectral wavelengths to silver halide in the same or different photosensitive layers to enable writing on the same photosensitive material using light sources having different wavelengths. Can also. In addition to the sensitizing dye, a dye which does not itself have a spectral sensitizing effect or a compound which does not substantially absorb visible light and exhibits supersensitization (supersensitizer) can be added to the emulsion. Good. Spectral sensitizing dyes are described in Research Disclosure Magazine, No. 17643 (197
December, 8), pp. 23-24, for supersensitizers
No. 18716 (November 1979), p. 649,
Each is listed.

[Organic metal salt] The photosensitive layer may contain an organic metal salt together with silver halide. Organic silver salts are particularly preferred as the organic metal salts. Examples of the organic compound used to form the organic silver salt include triazoles, tetrazoles, imidazoles, indazoles, thiazoles, thiadiazoles, azaindenes, and aliphatic, aromatic, or aromatic compounds having a mercapto group as a substituent. Heterocyclic compounds can be mentioned. Further, silver salts of carboxylic acids and silver acetylene can also be used as organic silver salts. Two or more organic silver salts may be used in combination. The organic silver salt is used in an amount of 10 ^{-5 to} 10 mol, preferably 10 ^{-4 to} 1 mol, per 1 mol of silver halide.

[Reducing Agent] The reducing agent has a function of reducing silver halide or a function of accelerating polymerization of a polymerizable compound (or crosslinking of a crosslinkable polymer). As the reducing agent, hydrazines, hydroquinones, catechols,
p-aminophenols, p-phenylenediamines,
3-pyrazolidones, 3-aminopyrazoles, 4-amino-5-pyrazolones, 5-aminouracils, 4,
5-dihydroxy-6-aminopyrimidines, reductones, aminoreductones, o- or p-sulfonamidophenols, o- or p-sulfonamidonaphthols, o- or p-acylaminophenols,
2-Sulfonamide indanones, 4-sulfonamido-5-pyrazolones, 3-sulfonamidoindoles, sulfonamidopyrazolobenzimidazoles, sulfonamidopyrazolotriazoles and α-sulfonamidoketones are used.

The reducing agent is described in JP-A-61-183640,
Nos. 61-188535, 61-228441, 62-70836, 62-86354 and 62-
No. 86355, No. 62-206540, No. 62-26
No. 4041, No. 62-109437, No. 63-254
442, JP-A-1-267536 and 2-1417
No. 56, No. 2-141775, No. 2-207254
And JP-A-2-262662 and JP-A-2-269352 (including those described as a developing agent or a hydrazine derivative). As for the reducing agent,
"The Theory of the Photographic Proces" by T. James
s "Fourth Edition, pp. 291-334 (1977), Research Disclosure, Vol. 170, No. 17029.
No. 9-15, (June 1978), and the same magazine, Vo
l.176, No.17643, pp.22-31, (1978
December). Further, Japanese Patent Application Laid-Open No. 62-210
As in the light-sensitive material described in Japanese Patent No. 446, a reducing agent precursor that releases the reducing agent under heating conditions or in contact with a base may be used instead of the reducing agent.

The basic reducing agent which forms a salt with an acid can be used in the form of a salt with a suitable acid. Two or more reducing agents may be used in combination. The interaction of two or more reducing agents is, first, to promote the reduction of silver halide (or organic silver salt) by so-called superadditivity, and second, to promote silver halide (or organic silver salt). It is conceivable that the oxidized form of the first reducing agent generated by the reduction of the compound causes a polymerization of the polymerizable compound through an oxidation-reduction reaction with another coexisting reducing agent. The reducing agent is preferably used in an amount of 0.1 to 10 mol per mol of silver halide.
It is more preferable to use 0.25 to 2.5 mol.

[Ethylenically unsaturated polymerizable compound] The polymerizable compound is a compound (monomer or oligomer) having an ethylenically unsaturated group capable of undergoing addition polymerization by free radicals. The ethylenically unsaturated polymerizable compound is described in JP-A-5-249667. Examples of ethylenically unsaturated polymerizable compounds include acrylic acid and salts thereof, acrylic esters, acrylamides, methacrylic acid and salts thereof, methacrylic esters, methacrylamides, maleic anhydride, maleic esters, Examples include itaconic esters, styrenes, vinyl ethers, vinyl esters, N-vinyl heterocycles, allyl ethers and allyl esters. Acrylic esters or methacrylic esters are particularly preferred. Specific examples of (meth) acrylates include pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyester (meth) acrylate and polyurethane (meth) acrylate Can be mentioned. Two or more ethylenically unsaturated polymerizable compounds may be used in combination. When the ethylenically unsaturated polymerizable compound is hydrophobic, it is preferable that the compound is emulsified and dispersed in an aqueous solution of a water-soluble polymer described later and added to the photosensitive layer. The water-soluble ethylenically unsaturated polymerizable compound can be uniformly dissolved in an aqueous solution of a water-soluble polymer. The amount of the polymerizable compound is preferably in the range of 0.1 to 5 g, more preferably 0.3 to 2 g, per gram of the water-soluble polymer.

[Hydrophilic fine particles] The hydrophilic fine particles improve the water retention of the polymerized image area, and adhere to the printing ink (ground stain).
Has the function of preventing Examples of hydrophilic fine particles include:
Metal oxide (eg, silicon dioxide, aluminum oxide, zinc oxide, titanium dioxide) particles, alkaline earth metal salt (eg, magnesium carbonate, calcium carbonate, barium sulfate) particles and natural polymer (eg, starch, cellulose) particles Can be mentioned. The particle size of the hydrophilic fine particles is preferably in the range of 0.1 to 50 μm.
The amount of the hydrophilic fine particles to be added is 0.1 g / g of the water-soluble polymer.
It is preferably in the range of 1 to 5 g.

[Anti-fogging agent, silver development accelerator, stabilizer]
To improve the photographic properties, the photosensitive layer can contain an antifoggant, a silver development accelerator or a stabilizer. Examples thereof include a mercapto compound (JP-A-59-1116).
No. 36), azoles and azaindenes (Research Disclosure Magazine No. 17643, 24-
Page 25 (1978)), carboxylic acids and phosphoric acids containing nitrogen (described in JP-A-59-168442), cyclic amides (described in JP-A-61-151841), and thioethers (described in JP-A-62-14841). No. 151842), polyethylene glycol derivatives (Japanese Unexamined Patent Publication No. Sho 62-62).
No. 151843), thiols (JP-A-62-1)
No. 51844), acetylene compounds (Japanese Unexamined Patent Publication No.
2-87957) and sulfonamide (described in JP-A-62-178232). As the silver development accelerator or the antifoggant, an aromatic ring (carbon ring or heterocyclic) mercapto compound (described in JP-A-6-313967) is particularly preferred. Aromatic heterocyclic mercapto compounds, particularly mercaptotriazole derivatives, are more preferred. The mercapto compound may be added to the light-sensitive material as a mercapto silver compound (silver salt). The amount of these compounds used is in the range of 10 ^-7 mol to 1 mol per mol of silver halide.

[Thermal Development Accelerator] In order to accelerate the thermal development and perform the thermal development treatment at a lower temperature or in a shorter time, a thermal development accelerator can be added to the photosensitive layer or the overcoat layer described later. As the thermal development accelerator, a compound having a plasticizing effect at room temperature or upon heating with respect to a binder used in any layer of the photosensitive material, or a compound having no plasticizing effect but capable of melting in the layer by heating is used. Can be used. It is considered that the thermal development accelerator promotes thermal development by promoting the diffusion of the reactant in the photosensitive material or by promoting the reaction itself.
Examples of the compound having a plasticizing effect include “Plastic Additives, 2nd Edition”, “Plastics Additives, 2nd Edition”, Taiseisha, P21-63;
ser Publishers) Polymer plasticizers described in Chapter 5, pages 251-296 can be used. Preferred thermal development accelerators include polyethers (eg, polyethylene glycol, polypropylene glycol), polyhydric alcohols (eg, glycerin, hexanediol), sugars (eg, sorbitol), formate esters, ureas (eg, urea, diethyl) Urea, ethylene urea), amides (eg, acetamide, propionamide, malonamide), sulfamides, sulfonamides, urea resins and phenol resins. Two or more thermal development accelerators can be used in combination. Further, it may be added in two or more layers. The amount of the thermal development accelerator added is 0.0
5 to 2 g / m ² , preferably 0.1 to 1 g / m ^2.
g / m ² is more preferable.

[Development Stopping Agent] Various development stopping agents can be used for the purpose of always obtaining a constant image with respect to the processing temperature and the processing time during thermal development. A development terminator is a compound that immediately neutralizes a base or reacts with a base to reduce the base concentration in a layer and stop development after proper development, or a compound that interacts with silver and a silver salt to suppress development. is there.
Specifically, an acid precursor that releases an acid upon heating,
An electrophilic compound that undergoes a substitution reaction with a coexisting base upon heating, or a nitrogen-containing heterocyclic compound, a mercapto compound, and a precursor thereof can be used. The thermal development terminator is described in JP-A-62-253159 and JP-A-2-2-159.
Nos. 42447 and 2-262661.

[Base and Base Precursor] It is preferable to add a base or a base precursor to the photosensitive layer or the overcoat layer described later. As the base, various inorganic and organic bases are used. As the base precursor, those precursors (decarboxylation type, pyrolysis type,
Reaction type, complex salt forming type or dissociation type) can be used. From the viewpoint of storage stability of the photosensitive material, a base precursor is more preferable than a base. Examples of the decarboxylation type base precursor include salts of organic acids and bases which can be decarboxylated by heating (JP-A-63-316760, JP-A-64-68746, and JP-A-68-74646).
Nos. 9-180537 and 61-313431). Examples of the pyrolytic base precursor include urea compounds (JP-A-63-9663).
159). Examples of the reactive base precursor include transition metal acetylide (described in JP-A-63-25208). Examples of complex salt-forming base precursors include basic metal compounds that are poorly soluble in water (described in JP-A-1-28282). Examples of dissociative base precursors include alkali metal salts of organic acids (eg, sodium acetate, sodium salts of polymers having acidic groups). The base precursor is 50-200
Preferably, the base is formed at a temperature of 80 ° C, more preferably at 80 to 160 ° C. The amount of the base or base precursor to be added is per mole of silver halide.
It is preferably in the range of 0.4 to 20 moles,
More preferably, it is in the range of 1 to 10 mol.

[Polymerization Inhibitor] In order to prevent polymerization of the polymerizable compound during storage of the photosensitive material, the photosensitive layer may contain a polymerization inhibitor. Conventionally known polymerization inhibitors (eg,
Nitrosamines, ureas, thioureas, thioamides, phenols, amines) can be used.

[Water-soluble polymer] Examples of the water-soluble polymer include polyvinyl alcohol (including modified polyvinyl alcohol), polyvinyl pyrrolidone, poly (meth) acrylate (eg, sodium salt), poly (meth) acrylamide, and polystyrene sulfone. Acid salts (eg, sodium salt), cellulose ethers (methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose sodium salt), gelatin, and gum arabic can be exemplified. Polyvinyl alcohol is particularly preferred. Polyvinyl alcohol has a saponification degree of 70 in order to reduce oxygen permeability.
% Or more, more preferably 80% or more, most preferably 90% or more. However, as described later, when an overcoat layer containing polyvinyl alcohol having a saponification degree of 90% or more is provided, the water-soluble polymer of the photosensitive layer may be an oxygen-permeable polymer. The molecular weight of the water-soluble polymer is 3000 to 500
000 is preferred. The coating amount of the water-soluble polymer is preferably in the range of 0.1 to 10 g / m ² , and more preferably in the range of 0.2 to 3 g / m ² .

[Overcoat layer] An overcoat layer can be provided on the photosensitive layer. The overcoat layer has a function of protecting the photosensitive layer and preventing oxygen in the air from penetrating into the photosensitive layer during image formation and inhibiting polymerization of the polymerizable compound. The overcoat layer contains a water-soluble polymer. As the water-soluble polymer, the polymer used for the photosensitive layer described above is used. Polymers with low oxygen permeability are preferred. Polyvinyl alcohol having a saponification degree of 90% or more is particularly preferably used. The thickness of the overcoat layer is preferably in the range of 0.3 to 20 μm, more preferably in the range of 0.5 to 7 μm.

[Colorant] A colorant can be added to a printing plate for the purpose of preventing halation and irradiation, and adjusting the coloring or sensitivity (absolute sensitivity and spectral sensitivity) of an image. As the colorant, known pigments and dyes can be used as long as they do not significantly impair the photosensitivity and polymerizability of the photosensitive layer. When a colorant is used for the purpose of preventing halation or irradiation, the colorant is preferably added to the ink receiving layer or the photosensitive layer.
When used for coloring an image, a colorant is preferably added to the photosensitive layer. It is preferable that the coloring agent for preventing halation and irradiation absorbs light in the photosensitive wavelength range of the optical sensor. When used for the purpose of adjusting the sensitivity, the colorant is preferably added to the overcoat layer or the photosensitive layer. The coloring agent can be added to the intermediate layer described below. As a coloring agent, see
Pigment, dye or colloidal silver described in JP-A-249669, Color Index Handbook and Dye Handbook (edited by The Society of Synthetic Organic Chemistry, 1970) can be used. Dyes for preventing irradiation which have little influence on the sensitivity of silver halide are disclosed in JP-B-41-20389 and JP-B-43-3.
Nos. 504, 43-13168 and JP-A-2-39.
No. 042, and US Pat. No. 3697037;
No. 3,423,207, British Patent Nos. 1,030,392 and 1,100,546. The amount of the colorant added is preferably in the range of 0.01 to 2 g / m ² ,
The range is more preferably from 0.05 to 1 g / m ² .

[Surfactant] A known surfactant may be added to any of the layers. Any of a nonionic activator, an anionic activator, a cationic activator and a fluorine activator can be used. For the surfactant, see JP-A-2-195356.
There is a description in the publication. Sorbitans, polyoxyethylenes and fluorinated surfactants are particularly preferred.

[Intermediate layer] An intermediate layer can be provided between the respective layers. The intermediate layer functions as an adhesive layer between layers, an antihalation layer containing a coloring agent, or an optical filter layer. The intermediate layer preferably contains the above water-soluble polymer. The thickness of the intermediate layer is preferably 5 μm or less.

[Image exposure] Image exposure is performed using light having a wavelength corresponding to the spectral sensitivity of silver halide. The wavelength is generally visible light, near ultraviolet light, or near infrared light, but X-rays or electron beams may be used. Examples of the light source include a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, various lasers (eg, a semiconductor laser, a helium neon laser, a helium cadmium laser, a YAG laser, an argon laser), a light emitting diode. And a cathode ray tube. The exposure amount is preferably in the range of 0.001 to 1000 μJ / cm ² , and 0.01 to 100 μJ / cm ^2.
More preferably, it is within the range. When the support is transparent, image exposure can also be performed through the support from the back side of the support.

[Thermal Development] Thermal development can be performed by a method in which the printing original plate is brought into close contact with a heated object (eg, a metal plate or a metal roller), a method in which the printing plate is immersed in a heated liquid, a method in which infrared rays are irradiated, or the like. . The surface of the printing original plate may be exposed to the air and heated from the support side, or the surface may be heated in a state where the surface is in close contact with a heated object and the air is shut off. When the surface is opened to the air and heated, oxygen in the air may penetrate into the printing original plate and inhibit the polymerization reaction. Therefore, the polymer having a low oxygen transmittance described above is formed in the photosensitive layer or the overcoat layer. It is preferable to use-. The heating temperature is 60 to 200 ° C., preferably 100 to 16
It is in the range of 0 ° C. The heating time ranges from 1 to 180 seconds, preferably from 5 to 60 seconds.

[Washing] The temperature of the water used in the washing step is 1
0 to 100 ° C., preferably 20 to 70 ° C.
Is more preferable. The washing step is preferably carried out by rubbing the printing original plate with a brush or sponge in water. The time for immersing the printing plate in water is 10
To 120 seconds, more preferably 30 to 60 seconds. The water used in the washing process includes
A surfactant or an organic solvent miscible with water (however, the amount used may be 30% by weight or less of the total amount with water) may be added.

[0036]

【Example】

[Example 1] Preparation of printing original plate "Preparation of ink-receiving substrate" A 3 wt% solution of polymethyl methacrylate (molecular weight: 50,000) (solvent: 100 µm) on a polyethylene terephthalate film (support) having a thickness of 100 µm. A mixed solvent of methyl ethyl ketone and propylene glycol monomethyl ether in a weight ratio of 1: 1) was applied and dried to provide an ink-receiving layer having a thickness of 1 μm to prepare an ink-receiving substrate.

"Preparation of silver halide emulsion" A solution containing gelatin, potassium bromide and water, and adding sodium hydroxide to adjust the pH at room temperature to 9.5 was heated to 55 ° C. After adding the thioether compound in an amount equivalent to 2.0 × 10 ⁻³ mol with respect to the total amount of silver nitrate, while maintaining the pAg in the reaction vessel at 9.0, an aqueous solution of silver nitrate and potassium iodide and silver nitrate were added. pAg and potassium bromide aqueous solution containing rhodium chloride so that 2 × 10 ^-7 mol in a molar ratio of rhodium to the total amount of
Silver iodobromide particles were formed by the addition of a controlled double jet method. Subsequently, sulfuric acid was added to adjust the pH to 6.0, and subsequently, at 55 ° C. and pAg = 8.6, an aqueous silver nitrate solution and a molar ratio of iridium to silver of 5 × 10 ^{−7 were used.}
An aqueous solution of potassium bromide to which hexachloroiridate (III) was added in a molar amount was added in two stages by a double jet method to prepare core / shell type silver iodobromide emulsion particles having the following composition.

Core: silver iodobromide (silver iodide content: 8.5 mol%) Shell: pure silver bromide Core / shell: 3/7 (silver molar ratio) Average silver iodide content: 2.55 Mol% average particle size: 0.30 μm

These emulsion grains were monodispersed, and 98% of the total number of grains was within ± 40% of the average grain size. Next, the emulsion was desalted, and the pH was adjusted to 6.5 and p
After adjusting the Ag to 9.0, while stirring at 50 ° C. while stirring, a methanol solution of the following two kinds of spectral sensitizing dyes A and B mixed at a 2: 1 molar ratio was added to a total of 8 × 10 5 dyes. ^-4 mol / mol Ag was added in an amount equivalent to Ag to obtain a spectrally sensitized emulsion.

[0040]

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[0041]

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[0042]

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"Preparation of Reducing Agent Dispersion" 10 g of the following reducing agent powder was dispersed in 90 g of a 10% by weight aqueous solution of polyvinyl alcohol using a Dynomill disperser.

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"Preparation of emulsion of polymerizable compound" A solution in which 1 g of copper phthalocyanine powder was dispersed in 20 g of trimethylolpropane triacrylate (ethylenically unsaturated polymerizable compound) was prepared by adding polyvinyl alcohol (degree of saponification: 80%). 100 g of a 10% by weight aqueous solution and 2 g of a 5% by weight aqueous solution of the following surfactant were added, and the mixture was dispersed with a homogenizer to prepare a polymerizable compound emulsion.

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[Formation of photosensitive layer] A coating solution having the following composition was
The photosensitive layer having a thickness of 2.0 μm was provided by coating and drying on the ink-receiving substrate.

塗布 Photosensitive layer coating solution─────── ───────────────────────────── Water 41.0 g 5% by weight aqueous solution of the above surfactant 6.0 g Polyvinyl alcohol (Ken) 47.0 g of the above-mentioned polymerizable compound emulsion 58.0 g silica gel powder (average particle size: 1 μm) 3.0 g the above reducing agent dispersion 20.0 g of the following mercapto compound 2.7 g of 0.5% by weight methanol solution 33.0 g of a mixture of 10 g of the silver halide emulsion and 43 g of water ─────────────

[0049]

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"Preparation of Base Precursor Dispersion" 250 g of the base precursor powder described below was mixed with polyvinyl alcohol (degree of saponification: 80%) using a Dynomill disperser.
It was dispersed in 750 g of a weight% aqueous solution.

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[Formation of Overcoat Layer] A coating solution having the following composition was applied on the above-mentioned photosensitive layer and dried to form an overcoat layer having a thickness of 3.5 μm to prepare a printing original plate.

塗布 Coating solution for overcoat layer────── １０ 100.0 g of 10% by weight aqueous solution of acid-modified polyvinyl alcohol (degree of saponification: 98%) 6.0 g of the base precursor dispersion 2.0 g of a 5% by weight aqueous solution of the surfactant ────────

(Plate making) A document (200 lpi mesh image for printing) and a step wedge) and a band-pass filter (transmitting light having a wavelength of about 670 nm) are brought into close contact with the printing original plate, and a xenon flash lamp is used. An image was exposed with an energy amount of ² μJ / cm ² at an exposure time of 10 ⁻⁴ sec. Next, when heat development was performed for 20 seconds while the support side of the printing original plate was in close contact with a hot plate heated to 150 ° C.,
A silver image was developed in the exposed area. Next, when immersed in water at 40 ° C. and washed with a brush for 20 seconds, the unexposed portion of the photosensitive layer is eluted and removed from the ink receiving substrate, and the exposed portion of the photosensitive layer is placed on the ink receiving substrate. Remaining, a blue image was formed. When printing was performed using this image (printing plate), the ink adhered only to the unexposed portions, and a good printed matter was obtained.

Example 2 The following coating solution was applied onto the ink-receiving substrate of Example 1 and dried to form a film having a thickness of 2.3.
A printing plate was prepared by providing a photosensitive layer having a thickness of μm (excluding an overcoat layer).

感光 Coating solution for photosensitive layer─────── ───────────────────────────── Water 36.0 g 5% by weight aqueous solution of surfactant of Example 1 6.0 g Polyvinyl alcohol 47.0 g of a 10% by weight aqueous solution of -toluene (degree of saponification: 80%) 48.0 g of the polymerizable compound emulsion of Example 1 58.0 g of silica gel powder (average particle diameter: 1 μm) 3.0 g 20.0 g 0.5% by weight methanol solution of the mercapto compound of Example 1 2.7 g Base precursor dispersion of Example 5.0 5.0 g Mixed solution of 10 g of silver halide emulsion of Example 1 and 43 g of water 33.0 g ─────────────────────────────────

The above printing original plate was image-exposed in the same manner as in Example 1, and then heat-developed for 20 seconds while the photosensitive layer side of the printing original plate was in close contact with a hot plate heated to 150 ° C. Next, when washing was performed in the same manner as in Example 1, an image similar to that in Example 1 was formed. When printing using this image,
Good printed matter was obtained.

Example 3 The printing original plate of Example 1 was subjected to image exposure and heat development in the same manner as in Example 1. This was directly mounted on a printing machine without washing, and printing was started.
The first few sheets had little printing ink attached,
After that, the ink rapidly starts to adhere to the unexposed areas, and after 20 sheets, the case of Example 1 (mounted on the printing press after the water washing process)
In the same manner as in Example 1, good printed matter was obtained.

Example 4 In preparing the ink-receiving substrate of Example 1, 3% by weight of a novolak resin (molecular weight: 50,000) was used instead of the 3% by weight solution of polymethyl methacrylate used for the ink-receiving layer. % Solution (solvent: a mixed solvent of methyl ethyl ketone and propylene glycol monomethyl ether at a 1: 1 weight ratio) is applied and dried to a film thickness of 1%.
A μm ink-receiving layer was provided to produce an ink-receiving substrate. Using the prepared ink receptive substrate, a printing original plate was prepared in the same manner as in Example 1, and treated in the same manner as in Example 1. As a result, an image similar to that in Example 1 was formed. When printing was performed using this image, a good printed matter was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a preferred embodiment of a printing original plate of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state after image exposure and heat development processing are performed on a printing original plate.

FIG. 3 is a schematic cross-sectional view showing a state after further performing a water washing process on a printing original plate after heat development.

FIG. 4 is a schematic sectional view showing a state in which printing is being performed.

[Explanation of symbols]

 Reference Signs List 1 support 2 ink-receiving layer 3 photosensitive layer 4 overcoat layer 5, 12 hydrophilic fine particles 6 unexposed part of photosensitive layer 7 exposed part of photosensitive layer 8, 11 polymerized image 9, 13 exposed ink-receiving layer 10 wet Water 14 oil-based ink

Claims (3)

[Claims] 1. An ink-receiving substrate comprising: a silver halide;
A lithographic printing plate precursor provided with a water-soluble photosensitive layer containing a reducing agent, an ethylenically unsaturated polymerizable compound, a water-soluble polymer and hydrophilic fine particles. 2. The lithographic printing original plate according to claim 1, wherein the ink receiving substrate is a substrate having an ink receiving layer provided on a support. 3. The method according to claim 1, further comprising a saponification degree of 90 on the photosensitive layer.
The lithographic printing original plate according to claim 1, wherein an overcoat layer containing polyvinyl alcohol of at least% is provided.