JP2006231730A - Printing plate material and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate material which necessitates no wet type development, in particular, and excels in starting properties of printing and in plate wear resistance. <P>SOLUTION: The printing plate material comprises a hydrophilic thermal image forming layer whose surface is made lipophilic by heating on a base. The hydrophilic thermal image forming layer contains particles of a polyvalent metal salt of a carboxylic acid compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lithographic printing plate material and a printing method using the same, and more particularly to a processless printing plate material used in a computer-to-plate (hereinafter referred to as CTP) method and a printing method using the same.

  2. Description of the Related Art In recent years, CTP (computer to plate) systems that record digital image data directly on a printing plate material with a laser light source have become widespread in the technology for producing printing plates for offset printing.

  In addition, as a printing plate material used in these CTP systems, a printing plate that can be applied to a conventional printing machine without requiring a developing treatment with a processing solution containing a special agent (for example, alkali, acid, solvent, etc.). For example, a phase change type printing plate material that does not require development processing at all, a printing plate material that is processed with water or a substantially neutral processing liquid mainly composed of water, on a printing press There are known printing plate materials called chemical-free type printing plate materials and processless type printing plate materials, such as printing plate materials that are developed at an initial stage of printing and do not require a development step.

  As the above-mentioned phase change type printing plate material, for example, an image area / non-image can be formed by forming a porous thin layer having a photothermal conversion function on the phase change hydrophilic layer. There is known a printing plate material (see Patent Document 1) that can form a lipophilic / hydrophilic difference in part.

  With this printing plate material, a printing plate can be obtained without treatment after image exposure, but there are problems such as insufficient printing durability.

  Further, as a processless type printing plate material, an on-press development type printing plate material that removes a non-image portion of an image forming layer on a printing machine is known, and printing using the printing plate material that has been image-exposed is known. A plate making method is known in which dampening water and printing ink are supplied from a dampening water supply roller and printing ink supply roller of a printing machine to the plate material, and development is performed on the printing machine (see, for example, Patent Documents 2 and 3). .)

  On-press development type printing plate materials include, for example, thermoplastic fine particles, water-soluble binders, photothermal heat on a hydrophilic layer or aluminum grain as disclosed in Japanese Patent No. 2938397 and Japanese Patent No. 2938398. A printing plate material provided with a heat-sensitive image forming layer containing a conversion material, or a printing plate material in which a photothermal conversion material is contained in a hydrophilic layer and an image is formed by heat generation of the light-heat conversion material is known (Patent Document) 4).

However, the method of developing an exposed printing plate material on a printing machine using these processless type printing plate materials does not require a special wet development process, and a relatively high-definition image can be obtained. However, when printing, in order to obtain a printed matter, there are cases in which a large number of pieces of waste paper are used before printing is started, and there is a problem that printing durability is insufficient.
JP 2001-88456 A JP 9-211182 A JP 2002-219881 A JP 2003-231374 A

  An object of the present invention is to provide a printing plate material that does not particularly require wet development, has excellent printability during printing, and has excellent printing durability.

  The object of the present invention is achieved by the following constitution.

(Claim 1)
A printing plate material having a hydrophilic thermosensitive image forming layer whose surface is oleophilic on heating on a substrate, the hydrophilic thermosensitive image forming layer containing polyvalent metal salt particles of a carboxylic acid compound Printing plate material characterized by.

(Claim 2)
A printing plate material having a heat-sensitive image forming layer that can be developed on-press on a substrate, wherein the heat-sensitive image forming layer contains polyvalent metal salt particles of a carboxylic acid compound.

(Claim 3)
A printing method comprising: exposing an image of the printing plate material according to claim 1 or 2 and printing using an oxidation polymerization drying type printing ink.

(Claim 4)
The printing plate material according to claim 1, wherein the hydrophilic thermosensitive image forming layer contains a thermally polymerizable compound or a thermally crosslinkable compound.

(Claim 5)
The printing plate material according to claim 2, wherein the heat-sensitive image forming layer contains a thermally polymerizable compound or a thermally crosslinkable compound.

(Claim 6)
The printing plate material according to claim 1, wherein the hydrophilic thermosensitive image forming layer contains a thermally crosslinkable wax and a crosslinking agent.

(Claim 7)
The printing plate material according to claim 2, wherein the heat-sensitive image forming layer contains a heat-crosslinking wax and a crosslinking agent.

Moreover, the particularly preferable configuration of the present invention is the following configuration.
(8)
The printing plate material according to claim 1 or 2, wherein the carboxylic acid compound is naphthenic acid or octenoic acid.
(9)
The printing plate material according to claim 1 or 2, wherein the metal of the multivalent metal salt particles is Co, Mn, Fe, or Zn.
(10)
The printing plate material according to claim 1 or 2, wherein the polyvalent metal salt particles have an average particle size of 0.2 to 2 µm.

  According to the above configuration of the present invention, it is an object to provide a printing plate material which does not particularly require wet development, has excellent printing performance during printing, and has excellent printing durability.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to a printing plate material having a hydrophilic thermosensitive image forming layer whose surface is oleophilic by heating on a substrate, and the hydrophilic thermosensitive image forming layer is a polyvalent metal salt particle of a carboxylic acid compound. It is characterized by containing.

  Further, the present invention is characterized in that in a printing plate material having a thermal image forming layer that can be developed on-machine on a substrate, the thermal image forming layer contains polyvalent metal salt particles of a carboxylic acid compound. .

  In particular, the present invention provides a printing plate material that is excellent in printing performance at the time of printing and excellent in printing durability by containing polyvalent metal salt particles of an organic carboxylic acid compound in a layer that forms an image by heat. be able to.

(Polyvalent metal salt particles of carboxylic acid compound)
The hydrophilic thermosensitive image forming layer according to the present invention contains particles of a polyvalent metal salt of a carboxylic acid compound.

  The carboxylic acid compound according to the present invention is an organic compound having a carboxyl group and can form a salt with a polyvalent metal.

  Examples of the carboxylic acid compound include fatty acids and cyclic compounds having a carboxyl group.

  Among these, as the carboxylic acid compound according to the present invention, acid compounds classified into fatty acids, resin acids, aromatic carboxylic acids, araliphatic carboxylic acids, heterocyclic carboxylic acids, and the like can be preferably used. .

  Examples of fatty acids include n-octanoic acid, 2,2-dimethylhexanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, 2,2-dimethylheptanoic acid, n-decanoic acid, 2,2-dimethyloctanoic acid, Saturated and unsaturated fatty acids having 4 or more carbon atoms, such as n-undecanoic acid, ricinoleic acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, and alginic acid, are preferred.

  The fatty acid is preferably a saturated or unsaturated fatty acid having 4 to 30 carbon atoms, and particularly preferably a saturated or unsaturated fatty acid having 6 to 12 carbon atoms such as octenoic acid.

  As the resin acid, for example, resin acids such as abietic acid, neoabietic acid, d-pimalic acid, isod-pimalic acid, cinnamic acid, and p-oxycinnamic acid can be preferably used.

  Examples of the aromatic carboxylic acid, the araliphatic carboxylic acid, and the heterocyclic carboxylic acid include cyclohexane carboxylic acid, naphthenic acid, benzoic acid, pt-butyl benzoic acid, trail acid, and diphenyl-4-carboxylic acid. Acid, salicylic acid, 3,5-di-t-butylsalicylic acid, α-naphthoic acid, β-naphthoic acid, diphenylacetic acid, phenoxyacetic acid, (4-piperidinyl) acetic acid, (3-furyl) acetic acid, and the like. Of these, naphthenic acid is particularly preferably used.

  The polyvalent metal of the polyvalent metal salt particles according to the present invention is a polyvalent metal capable of forming a salt with the acid, and examples of the polyvalent metal include Co, Mn, Ce, Pb, Cu, Ca, Zn, Zr, Fe and the like can be mentioned, and among these, Co, Mn, Fe and Zn are preferable.

  As the polyvalent metal salt of the carboxylic acid compound, naphthenic acid and Co and Zn salts of octenoic acid are preferable because of their high reactivity. However, from the viewpoint of safety and environment, Zn naphthenate and Zn octenoate are particularly preferable. Is preferably used.

  The polyvalent metal salt of the carboxylic acid compound is contained as particles in the image forming layer.

  By being contained as particles in the image forming layer, the hydrophilicity of the surface of the image forming layer in the unexposed area is not deteriorated, and in the exposed area, it is melted and diffused in the image forming layer. Because of the leaching, it is presumed that the printing plate material of the present invention is excellent in printing performance and printing durability.

  The average particle size of the particles is preferably 0.05 to 5 μm, more preferably 0.2 to 2 μm from the viewpoint of particle formation, production cost, prevention of contamination, resolution, sensitivity, and the like, and It is preferably smaller than the film thickness of the image forming layer.

  Here, the average particle diameter is a volume average particle diameter measured using a known laser diffraction / scattering particle size distribution measuring apparatus.

  The method for granulating the polyvalent metal salt of fatty acid or resin acid is not particularly limited, but after dissolving the polyvalent metal salt in an appropriate organic solvent, it is mixed with additives such as water and an emulsifier and stirred vigorously. It is possible to obtain uniform particles by making an emulsion and then removing the organic solvent by heating and suction.

  The fine particles can also be formed by a mechanical dispersion method as described in JP-A-11-309366.

  The content of the polyvalent metal salt with respect to the heat-sensitive image forming layer is preferably 0.1% by mass to 50% by mass, particularly preferably 1% by mass to 30% by mass, from the viewpoints of printability, printing durability, and sensitivity. preferable.

(First aspect)
A first aspect of the present invention, that is, a printing plate material having a hydrophilic thermosensitive image forming layer whose surface becomes oleophilic by heating on the substrate, the image forming layer comprising a large amount of fatty acid or resin acid. A configuration containing valent metal salt particles will be described.

  In the above configuration, the hydrophilic thermosensitive image-forming layer whose surface becomes oleophilic by heating is a layer that can be water-repellent when the exposed portion is dampened by a printing ink receiving portion during printing, The unexposed part of this exposure is a layer whose surface is dampened with water during printing and is printing ink repellent, and includes a hydrophilic material, a lipophilic precursor, and a photothermal conversion material.

  The hydrophilic thermosensitive image forming layer may be a single layer or a plurality of constituent layers, but the surface of the exposed portion after image exposure is oleophilic.

  When the hydrophilic thermosensitive image forming layer is composed of one layer, the hydrophilic thermosensitive image forming layer contains a hydrophilic material, a lipophilic precursor and a photothermal conversion material in this layer, and the polyvalent metal salt particles are contained in the layer. Including.

  When there are a plurality of hydrophilic thermosensitive image forming layers, at least the uppermost layer has hydrophilicity, and the surface of the exposed portion of the uppermost layer of the hydrophilic thermosensitive image forming layer becomes oleophilic by image exposure.

  In this case, the uppermost layer needs to be hydrophilic, but the other constituent layers may not be hydrophilic. Further, the photothermal conversion material may be contained in the hydrophilic thermosensitive image forming layer or may be contained in other constituent layers, and the polyvalent metal salt particles are contained in the constituent layer adjacent to the uppermost layer. It is preferable that

  The most preferable layer configuration of the first aspect is that the upper layer is a hydrophilic layer that does not contain a lipophilic precursor, and a hydrophilic lower layer that includes one or more lipophilic precursors and a photothermal conversion material is provided below the hydrophilic layer. It is the composition which has.

  In this case, the oleophilic precursor is melted by the heat generated by exposure and penetrates into the upper hydrophilic layer to make the surface of the hydrophilic layer oleophilic to form an image portion. The polyvalent metal particles according to the present invention are preferably contained in a lower layer adjacent to the upper hydrophilic layer, and the polyvalent metal particles are also melted by the heat generated by exposure and penetrate into the upper hydrophilic layer. It is preferable that it be present on the surface of the hydrophilic layer in the image area.

  The hydrophilic material contained in the hydrophilic thermosensitive image forming layer is preferably a hydrophilic material substantially insoluble in water, and particularly preferably a metal oxide.

  The metal oxide preferably contains metal oxide fine particles. Examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

  Among the above, colloidal silica can be preferably used in the present invention. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and good strength can be obtained even in a layer in which the material containing no carbon atom is 91% by mass or more.

  The colloidal silica preferably includes necklace-like colloidal silica and fine particle colloidal silica having an average particle size of 20 nm or less, and the colloidal silica preferably exhibits alkalinity as a colloidal solution.

  The necklace-like colloidal silica used in the present invention is a general term for an aqueous dispersion of spherical silica whose primary particle diameter is on the order of nm. The necklace-like colloidal silica used in the present invention means “pearl necklace-like” colloidal silica in which spherical colloidal silica having a primary particle diameter of 10 to 50 nm is bonded to a length of 50 to 400 nm. The pearl necklace shape (that is, the pearl necklace shape) means that the image in a state in which the silica particles of colloidal silica are connected and connected has a shape like a pearl necklace. The bond between the silica particles constituting the necklace-shaped colloidal silica is presumed to be —Si—O—Si— in which —SiOH groups present on the surface of the silica particles are dehydrated. Specific examples of the colloidal silica in the form of necklace include “Snowtex-PS” series manufactured by Nissan Chemical Industries, Ltd.

  Product names include “Snowtex-PS-S (average particle size in a connected state is about 110 nm)”, “Snowtex-PS-M (average particle size in a connected state is about 120 nm)” and “Snowtex- PS-L (the average particle size of the connected state is about 170 nm) ", and acidic products corresponding to these are" Snowtex-PS-SO "," Snowtex-PS-MO "and “Snowtex-PS-LO”.

  By adding necklace-like colloidal silica, it becomes possible to maintain the strength while ensuring the porosity of the layer, and it can be preferably used as a porous material for the layer.

  Among these, when “Snowtex PS-S”, “Snowtex PS-M”, and “Snowtex PS-L”, which are alkaline, are used, the strength of the hydrophilic layer is improved and the number of printed sheets is large. However, it is particularly preferable because the occurrence of soiling is suppressed.

  Further, it is known that the colloidal silica has a stronger binding force as the particle diameter is smaller, and it is preferable to use colloidal silica having an average particle diameter of 20 nm or less in the present invention, and more preferably 3 to 15 nm. preferable. In addition, as described above, alkaline colloidal silica is particularly preferable because alkaline colloidal silica has a high effect of suppressing the occurrence of soiling.

  Alkaline colloidal silica having an average particle size within this range includes “Snowtex-20 (particle size 10-20 nm)”, “Snowtex-30 (particle size 10-20 nm)”, “Snowtex” manufactured by Nissan Chemical Co., Ltd. -40 (particle diameter 10-20 nm) "," Snowtex-N (particle diameter 10-20 nm) "," Snowtex-S (particle diameter 8-11 nm) "," Snowtex-XS (particle diameter 4-6 nm) ) ".

  Colloidal silica having an average particle size of 20 nm or less is particularly preferable because it can be further improved in strength while maintaining the porous property of the layer when used in combination with the aforementioned necklace-like colloidal silica.

  The ratio of colloidal silica / necklace-shaped colloidal silica having an average particle diameter of 20 nm or less is preferably 95/5 to 5/95 (mass ratio), more preferably 70/30 to 20/80, and 60/40 to 30/70. Is more preferable.

  The hydrophilic layer of the printing plate material used in the present invention preferably contains porous metal oxide particles as a metal oxide. As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

  The porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in porosity and particle size by adjusting the production conditions.

  As the porous silica particles, those obtained from a wet gel are particularly preferable.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, amorphous composite particles synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, those produced as composite particles of three or more components by adding an alkoxide of another metal during production can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 1.0 ml / g or more in terms of pore volume before dispersion, more preferably 1.2 ml / g or more, and 1.8 to 2.5 ml / g. More preferably, it is as follows.

  The particle size is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, in a state where it is contained in the hydrophilic layer (including when crushed during dispersion, for example).

  The particle diameter of the porous inorganic particles is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, when contained in the hydrophilic layer.

  In addition, the hydrophilic layer of the printing plate material of the present invention may contain layered clay mineral particles as a metal oxide. Examples of the layered mineral particles include kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicate ( Kanemite, macatite, ialite, magadiite, kenyaite, etc.). Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As for the size of the layered mineral particles, the average particle size (maximum length of the particles) is 20 μm or less in the state of being contained in the layer (including the case where it has undergone the swelling process and dispersion peeling process), and the average aspect The ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, the average particle size is 5 μm or less, the average aspect ratio is more preferably 50 or more, and the average particle size is More preferably, it is 1 μm or less and the average aspect ratio is 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral.

  The content of the layered mineral particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added as a powder to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. It is preferable that the gel swollen in water is prepared and then added to the coating solution.

A silicate aqueous solution can also be used as another additive material in the hydrophilic thermosensitive image forming layer. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer using a metal alkoxide by a so-called sol-gel method can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Published by Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.

  In the present invention, a hydrophilic organic resin may be contained in the hydrophilic thermosensitive image forming layer.

  Examples of the hydrophilic organic resin include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, and acrylic. Examples thereof include resins such as polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone.

  In addition, the resin may contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, and acrylic resins having a tertiary amino group or a quaternary ammonium group. , Diacrylamine and the like. The cationic resin may be added in the form of fine particles. Examples thereof include a cationic microgel described in JP-A-6-161101.

  As the water-soluble material contained in the hydrophilic thermosensitive image forming layer, saccharides are preferable.

  As the saccharide, an oligosaccharide, which will be described in detail later, can be used, but it is particularly preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred.

  This is because the effect of forming the surface shape of the hydrophilic image forming layer in a preferable state can be obtained by incorporating the polysaccharide in the hydrophilic image forming layer.

  The surface of the hydrophilic thermosensitive image forming layer preferably has a concavo-convex structure with a pitch of 0.1 to 50 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area strength.

  Such a concavo-convex structure can be formed by containing an appropriate amount of filler having an appropriate particle size in the hydrophilic thermosensitive image forming layer. However, the above-mentioned alkaline colloidal silica is used in the coating solution for the hydrophilic image forming layer. And the above-mentioned water-soluble polysaccharide, and it is preferable that a structure having better printing performance can be obtained by forming a phase separation when applying and drying the hydrophilic image forming layer.

  The shape of the concavo-convex structure (such as pitch and surface roughness) is the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, the solid content concentration of the coating solution, and the wet film. The thickness and drying conditions can be appropriately controlled.

  The pitch of the concavo-convex structure is more preferably 0.2 to 30 μm, and further preferably 0.5 to 20 μm. Further, a concavo-convex structure having a multiple structure in which a concavo-convex structure having a smaller pitch is formed on the concavo-convex structure having a large pitch may be formed.

  As surface roughness, 100-1000 nm is preferable by Ra, and 150-600 nm is more preferable.

  The thickness of the hydrophilic thermosensitive image forming layer is from 0.01 to 50 μm, preferably from 0.2 to 10 μm, more preferably from 0.5 to 3 μm.

  The hydrophilic thermosensitive image forming layer coating solution for forming the hydrophilic thermosensitive image forming layer of the present invention may contain a water-soluble surfactant for the purpose of improving applicability. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains.

  The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic thermosensitive image forming layer (solid content as the coating solution).

  Further, the hydrophilic thermosensitive image forming layer can contain a phosphate. In the present invention, since the coating solution for the hydrophilic thermosensitive image forming layer is preferably alkaline, it is preferable to add the phosphate as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening at the time of printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

  Examples of the oleophilic precursor used in the hydrophilic thermosensitive image forming layer include heat-meltable particles and microcapsules enclosing a hydrophobic substance.

  The heat-meltable particles are particles formed of a material that has a low viscosity when melted, and is generally classified as a wax, among thermoplastic materials. The physical properties are preferably a softening point of 40 ° C. or higher and 120 ° C. or lower, a melting point of 60 ° C. or higher and 150 ° C. or lower, more preferably a softening point of 40 ° C. or higher and 100 ° C. or lower, and a melting point of 60 ° C. or higher and 120 ° C. or lower. When the melting point is less than 60 ° C., storage stability is a problem, and when the melting point is higher than 300 ° C., ink landing sensitivity is lowered.

  Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. These have a molecular weight of about 800 to 10,000. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups. Furthermore, in order to lower the softening point and improve the workability, these waxes are stearamide, linolenamide, laurylamide, myristamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide. Alternatively, methylolated products of these fatty acid amides, methylene bisstellaramide, ethylene bisstellaramide, and the like can be added. Coumarone-indene resin, rosin-modified phenol resin, terpene-modified phenol resin, xylene resin, ketone resin, acrylic resin, ionomer, and copolymers of these resins can also be used.

  Among these, it is preferable to contain any of polyethylene, microcrystalline, fatty acid ester, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, highly sensitive image formation can be performed.

  In addition, since these materials have lubricity, damage when a shearing force is applied to the surface of the printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

  The heat-meltable particles are preferably dispersible in water, and the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm, from the viewpoint of layer strength and resolution. It is.

  Moreover, the composition of the inside and the surface layer of the heat-meltable particles may be continuously changed, or may be coated with a different material.

  As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.

  As content of the heat-meltable particle | grains in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

Examples of the microcapsule include microcapsules enclosing a hydrophobic material described in JP-A-2002-2135 and JP-A-2002-19317.
The microcapsules preferably have an average diameter of 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm.

  In the present invention, it is particularly preferable that the hydrophilic image forming layer contains a polymerizable compound or a crosslinkable compound. Of these, it is particularly preferable to include a crosslinkable wax. When a crosslinkable compound is included, a crosslinker is preferably included.

  Examples of the polymerizable compound include compounds containing a polymerizable ethylenic double bond.

  The crosslinkable compound is not particularly limited as long as it is a compound having two or more hydroxyl groups, carboxyl groups, amino groups, epoxy groups, isocyanate groups, and other functional groups.

The functional group may be protected. Of these, polyfunctional blocked isocyanate compounds are preferred.
Examples of the crosslinkable wax include general oxidized wax. In particular, oxidized polyolefin waxes such as oxidized polyethylene wax and oxidized polypropylene wax are preferable, and it is preferable to have a plurality of functional groups such as hydroxyl groups and carboxyl groups in one molecule.

  The functional group of these crosslinkable waxes can be thermally cross-linked with, for example, a polyfunctional blocked isocyanate compound. It is presumed that the crosslinking reaction proceeds promptly and the image area strength can be improved, whereby an image area having high sensitivity and good printing durability can be formed.

(Photothermal conversion agent)
Examples of the photothermal conversion agent include infrared absorbing dyes or pigments.

(Infrared absorbing dye)
Examples of infrared absorbing dyes include organic compounds such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, and naphthalocyanine dyes. Azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-1-33547, JP-A-1-160683, JP-A-280750, JP-A-1-293342, JP-A-2-2074, JP-A-3-26593, 3-30991, 3-34891, 3-36093, 3-36094, 3-36095, 3-42281, 3-97589, 3-103476, 7 -43851, 7-102179, JP-A-2001-117201, and the like. These can be used alone or in combination of two or more.

  Examples of the pigment include carbon, graphite, metal, metal oxide and the like.

  As carbon, furnace black or acetylene black is particularly preferable. The particle size (d50) is preferably 100 nm or less, and more preferably 50 nm or less.

  As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

  As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.

As the metal oxide, a material that is black in the visible light region or a material that is conductive or that is a semiconductor can be used. Examples of the material exhibiting black color in the visible light region include black iron oxide (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more kinds of metals described above. Specifically, it is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. These can be produced by the methods disclosed in JP-A-8-27393, 9-25126, 9-237570, 9-241529, and 10-231441. The composite metal oxide that can be used in the present invention is particularly preferably a Cu-Cr-Mn-based or Cu-Fe-Mn-based composite metal oxide. In the case of a Cu—Cr—Mn system, it is preferable to perform the treatment disclosed in JP-A-8-27393 in order to reduce the elution of hexavalent chromium. These composite metal oxides are colored with respect to the amount added, that is, have good photothermal conversion efficiency. These composite metal oxides preferably have an average primary particle size of 1 μm or less, and more preferably have an average primary particle size in the range of 0.01 to 0.5 μm. When the average primary particle diameter is 1 μm or less, the photothermal conversion ability with respect to the addition amount becomes better, and when the average primary particle diameter is within the range of 0.01 to 0.5 μm, the photothermal conversion ability with respect to the addition amount is obtained. Better. However, the photothermal conversion ability with respect to the addition amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, it is preferable to disperse these composite metal oxide particles by a known method separately before adding them to the layer coating solution to prepare a dispersion (paste). An average primary particle size of less than 0.01 is not preferable because dispersion becomes difficult. A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles. Although the kind of dispersing agent is not specifically limited, it is preferable to use Si type surfactant containing Si element.

Examples of materials that have conductivity or are semiconductors include reduced Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , and TiO ₂ . Examples thereof include TiO (titanium oxynitride, generally titanium black). Further, it is also possible to use those obtained by coating the core material _{(BaSO 4, TiO 2, 9Al} 2 O 3 · 2B 2 O, K 2 O · nTiO 2 , etc.) in these metal oxides. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less.

  As addition amount of these photothermal conversion raw materials, it is 0.1-50 mass% with respect to the layer containing this, 1-30 mass% is preferable, and 3-25 mass% is more preferable.

  In the present invention, the hydrophilic material preferably has a function as a photothermal conversion material.

(Base material)
The base material used in the first embodiment is a plate-like body or a film body that can carry a hydrophilic thermosensitive image forming layer, and a known material used as a base material for a printing plate can be used.

  Examples of the substrate include a metal plate, a plastic film, paper treated with polyolefin, a composite substrate obtained by appropriately bonding the above materials, and the like.

  The thickness of the base material is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate used as the substrate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface.

  As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface. For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. A combination of the anodizing treatment and the dipping or coating treatment can also be used.

  Moreover, the aluminum base material roughened by a well-known method, what has what is called an aluminum grain can also be used as a base material.

  Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters. Among these, polyethylene terephthalate and polyethylene naphthalate are preferably used.

  These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment.

  Examples of the undercoat layer include a layer containing gelatin or latex. The undercoat layer may contain an organic or inorganic known conductive material.

  In addition, for the purpose of controlling the slipperiness of the back surface (for example, reducing the friction coefficient with the plate cylinder surface), a substrate provided with a back surface coating layer can also be preferably used.

(Second embodiment)
In the second aspect of the present invention, that is, a printing plate material having a heat-sensitive image forming layer that can be developed on the substrate, the heat-sensitive image forming layer contains polyvalent metal salt particles of a carboxylic acid compound. To do.

(Thermal image forming layer that can be developed on-machine)
The on-press developable heat-sensitive image forming layer according to the present invention refers to a dampening water or printing with a dampening water at the time of being subjected to a printing process without passing through a developing process after image exposure, that is, in a printing preparation stage. A heat-sensitive image forming layer that can form a printable image by removing a portion of the heat-sensitive image forming layer that becomes a non-image portion during printing with ink.

  The heat-sensitive image forming layer is a heat-sensitive image forming layer capable of forming an image by image exposure and capable of forming an image by heat generation of a layer containing a photothermal conversion agent that converts image exposure light into heat.

  The layer containing the photothermal conversion agent may be the heat-sensitive image forming layer according to the present invention, or may be a hydrophilic layer described later or another layer adjacent to the heat-sensitive image forming layer.

  As the heat-sensitive image forming layer, a so-called negative image forming layer in which the image forming layer in the exposed portion is changed in a direction to be fixed on the hydrophilic layer by heat is preferably used.

  Examples of the image forming layer in which the exposed portion is changed in a direction to be fixed on the hydrophilic layer by heat include, for example, a hydrophilic layer before exposure and from a hydrophilic layer to a hydrophobic layer by heat. And an image forming layer containing a hydrophobized precursor that can be changed.

  As the hydrophobizing precursor, thermoplastic hydrophobic particles such as heat-fusible particles or heat-fusible particles, or microcapsules enclosing a hydrophobic substance can be preferably used.

  Examples of the thermoplastic particles include heat-fusible particles and heat-fusible particles.

  The heat-meltable particles are particles made of a material that has a low viscosity when melted, and is generally classified as a wax, among thermoplastic materials. The physical properties are preferably a softening point of 40 ° C. or higher and 120 ° C. or lower, a melting point of 60 ° C. or higher and 150 ° C. or lower, more preferably a softening point of 40 ° C. or higher and 100 ° C. or lower, and a melting point of 60 ° C. or higher and 120 ° C. or lower. When the melting point is less than 60 ° C., storage stability is a problem, and when the melting point is higher than 300 ° C., ink deposition sensitivity is lowered.

  Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. These have a molecular weight of about 800 to 10,000. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups. Furthermore, in order to lower the softening point and improve the workability, these waxes are stearamide, linolenamide, laurylamide, myristamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide. Alternatively, methylolated products of these fatty acid amides, methylene bisstellaramide, ethylene bisstellaramide, and the like can be added. Coumarone-indene resin, rosin-modified phenol resin, terpene-modified phenol resin, xylene resin, ketone resin, acrylic resin, ionomer, and copolymers of these resins can also be used.

  Among these, it is preferable to contain any of polyethylene, microcrystalline, fatty acid ester, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, highly sensitive image formation can be performed.

  In addition, since these materials have lubricity, damage when a shearing force is applied to the surface of the printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

  The heat-meltable particles are preferably dispersible in water, and the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm from the viewpoint of on-press developability and resolution. It is.

  Moreover, the composition of the inside and the surface layer of the heat-meltable particles may be continuously changed, or may be coated with a different material.

  As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.

  As content of the heat-meltable particle | grains in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of heat-fusible particles include thermoplastic hydrophobic polymer particles, and there is no specific upper limit for the softening temperature of the polymer particles, but the temperature is lower than the decomposition temperature of the polymer particles. Is preferred. The weight average molecular weight (Mw) of the polymer is preferably in the range of 10,000 to 1,000,000.

  Specific examples of the polymer that constitutes the polymer particles include, for example, diene (co) polymers such as polypropylene, polybutadiene, polyisoprene, and ethylene-butadiene copolymer, styrene-butadiene copolymer, Synthetic rubbers such as methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, polymethyl methacrylate, methyl methacrylate- (2-ethylhexyl acrylate) copolymer, methyl methacrylate-methacrylic acid copolymer, methyl acrylate- ( (N-methylolacrylamide) copolymer, (meth) acrylic acid ester such as polyacrylonitrile, (meth) acrylic acid (co) polymer, polyvinyl acetate, vinyl acetate-vinyl propionate copolymer, vinyl acetate-ethylene copolymer Vinyl such as polymer Ester (co) polymer, vinyl acetate - (2-ethylhexyl acrylate) copolymers, polyvinyl chloride, polyvinylidene chloride, polystyrene and copolymers thereof. Of these, (meth) acrylic acid esters, (meth) acrylic acid (co) polymers, vinyl ester (co) polymers, polystyrene, and synthetic rubbers are preferably used.

  The heat-fusible particles are preferably dispersible in water, and the average particle size is preferably from 0.01 to 10 μm, more preferably from the viewpoint of on-press developability and sensitivity. ~ 3 μm.

  Further, the composition of the heat fusible particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.
As content of the thermoplastic fine particle in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

Examples of the microcapsule include microcapsules enclosing a hydrophobic material described in JP-A-2002-2135 and JP-A-2002-19317.
The microcapsules preferably have an average diameter of 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm.

  In the present invention, it is particularly preferable that the heat-sensitive image forming layer contains a polymerizable compound or a crosslinkable compound. Of these, it is particularly preferable to include a crosslinkable wax. When a crosslinkable compound is included, a crosslinker is preferably included.

  Examples of the polymerizable compound include compounds containing a polymerizable ethylenic double bond.

  The crosslinkable compound is not particularly limited as long as it is a compound having two or more hydroxyl groups, carboxyl groups, amino groups, epoxy groups, isocyanate groups, and other functional groups.

The functional group may be protected. Of these, polyfunctional blocked isocyanate compounds are preferred.
Examples of the crosslinkable wax include general oxidized wax. In particular, oxidized polyolefin waxes such as oxidized polyethylene wax and oxidized polypropylene wax are preferable, and it is preferable to have a plurality of functional groups such as hydroxyl groups and carboxyl groups in one molecule.

  The functional group of these crosslinkable waxes can be thermally cross-linked with, for example, a polyfunctional blocked isocyanate compound. At this time, the catalytic effect of the polyvalent metal salt of the organic carboxylic acid compound according to the present invention can be used with little heating energy. It is presumed that an image part having high sensitivity and good printing durability can be formed by the rapid progress of the crosslinking reaction and the improvement of the image part strength.

  Moreover, also in this aspect, it is preferable to have a layer containing a photothermal conversion material, and the same photothermal conversion material as described above can be used.

(Base material)
The base material used in this embodiment is a plate-like body or a film body that can carry a heat-sensitive image forming layer, and a known material used as a base material for a printing plate can be used.

  The substrate in this embodiment preferably has a hydrophilic layer. The hydrophilic layer is exposed when the non-image portion of the image forming layer is removed during printing, and can be dampening water receptive and printing ink repellent. Can be formed by a method of providing a hydrophilic layer, a method of coating a hydrophilic layer, or the like.

  Examples of the substrate include a metal plate, a plastic film, paper treated with polyolefin, a composite substrate obtained by appropriately bonding the above materials, and the like.

  The thickness of the base material is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate used as the substrate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface.

  As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface. For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. A combination of the anodizing treatment and the dipping or coating treatment can also be used.

  In addition, an aluminum base material roughened by a known method, that is, an aluminum base material having a hydrophilic layer obtained by subjecting so-called aluminum sand to a hydrophilic treatment, may be used as a base material having a hydrophilic layer. it can.

  Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

  Especially as a base material used for this invention, a polyethylene terephthalate and a polyethylene naphthalate are also preferably used.

  These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex. The undercoat layer may contain an organic or inorganic known conductive material.

  In addition, for the purpose of controlling the slipperiness of the back surface (for example, reducing the friction coefficient with the plate cylinder surface), a substrate provided with a back surface coating layer can also be preferably used.

(Hydrophilic layer)
The hydrophilic layer is a layer that can be a non-image portion where the printing ink does not deposit during printing as described above, and is a layer formed on the substrate or a surface layer when the substrate surface is made hydrophilic It is.

  The hydrophilic layer contains a hydrophilic material.

  One aspect of the printing plate material used in the present invention is an aspect having a hydrophilic layer coated on a substrate. In this case, the hydrophilic layer may be a single layer or a plurality of layers.

As the amount with the hydrophilic layer is preferably ^{0.1~10g / m 2, 0.2~5g / m} 2 is more preferable.

  As the hydrophilic material used for the hydrophilic layer, a hydrophilic material that is substantially insoluble in water is preferable, and a metal oxide is particularly preferable.

  The metal oxide preferably contains metal oxide fine particles. Examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

  Among the above, colloidal silica can be preferably used in the present invention. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and good strength can be obtained even in a layer in which the material containing no carbon atom is 91% by mass or more.

  The colloidal silica preferably includes necklace-like colloidal silica and fine particle colloidal silica having an average particle size of 20 nm or less, and the colloidal silica preferably exhibits alkalinity as a colloidal solution.

  The necklace-like colloidal silica used in the present invention is a general term for an aqueous dispersion of spherical silica whose primary particle diameter is on the order of nm. The necklace-like colloidal silica used in the present invention means “pearl necklace-like” colloidal silica in which spherical colloidal silica having a primary particle diameter of 10 to 50 nm is bonded to a length of 50 to 400 nm. The pearl necklace shape (that is, the pearl necklace shape) means that the image in a state in which the silica particles of colloidal silica are connected and connected has a shape like a pearl necklace. The bond between the silica particles constituting the necklace-shaped colloidal silica is presumed to be —Si—O—Si— in which —SiOH groups present on the surface of the silica particles are dehydrated. Specific examples of the colloidal silica in the form of necklace include “Snowtex-PS” series manufactured by Nissan Chemical Industries, Ltd.

  Product names include “Snowtex-PS-S (average particle size in a connected state is about 110 nm)”, “Snowtex-PS-M (average particle size in a connected state is about 120 nm)” and “Snowtex- PS-L (the average particle size of the connected state is about 170 nm) ", and acidic products corresponding to these are" Snowtex-PS-SO "," Snowtex-PS-MO "and “Snowtex-PS-LO”.

  By adding necklace-like colloidal silica, it becomes possible to maintain the strength while ensuring the porosity of the layer, and it can be preferably used as a porous material for the layer.

  Among these, when “Snowtex PS-S”, “Snowtex PS-M”, and “Snowtex PS-L”, which are alkaline, are used, the strength of the hydrophilic layer is improved and the number of printed sheets is large. However, it is particularly preferable because the occurrence of soiling is suppressed.

  Further, it is known that the colloidal silica has a stronger binding force as the particle diameter is smaller, and it is preferable to use colloidal silica having an average particle diameter of 20 nm or less in the present invention, and more preferably 3 to 15 nm. preferable. In addition, as described above, alkaline colloidal silica is particularly preferable because alkaline colloidal silica has a high effect of suppressing the occurrence of soiling.

  Alkaline colloidal silica having an average particle size within this range includes “Snowtex-20 (particle size 10-20 nm)”, “Snowtex-30 (particle size 10-20 nm)”, “Snowtex” manufactured by Nissan Chemical Co., Ltd. -40 (particle diameter 10-20 nm) "," Snowtex-N (particle diameter 10-20 nm) "," Snowtex-S (particle diameter 8-11 nm) "," Snowtex-XS (particle diameter 4-6 nm) ) ".

  Colloidal silica having an average particle size of 20 nm or less is particularly preferable because it can be further improved in strength while maintaining the porous property of the layer when used in combination with the aforementioned necklace-like colloidal silica.

  The ratio of colloidal silica / necklace-shaped colloidal silica having an average particle diameter of 20 nm or less is preferably 95/5 to 5/95 (mass ratio), more preferably 70/30 to 20/80, and 60/40 to 30/70. Is more preferable.

  The hydrophilic layer of the printing plate material used in the present invention preferably contains porous metal oxide particles as a metal oxide. As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

  The porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in porosity and particle size by adjusting the production conditions.

  As the porous silica particles, those obtained from a wet gel are particularly preferable.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, amorphous composite particles synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, those produced as composite particles of three or more components by adding an alkoxide of another metal during production can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 1.0 ml / g or more in terms of pore volume before dispersion, more preferably 1.2 ml / g or more, and 1.8 to 2.5 ml / g. More preferably, it is as follows.

  The particle size is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, in a state where it is contained in the hydrophilic layer (including when crushed during dispersion, for example).

  The particle diameter of the porous inorganic particles is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, when contained in the hydrophilic layer.

  In addition, the hydrophilic layer of the printing plate material of the present invention may contain layered clay mineral particles as a metal oxide. Examples of the layered mineral particles include kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicate ( Kanemite, macatite, ialite, magadiite, kenyaite, etc.). Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As for the size of the layered mineral particles, the average particle size (maximum length of the particles) is 20 μm or less in the state of being contained in the layer (including the case where it has undergone the swelling process and dispersion peeling process), and the average aspect The ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, the average particle size is 5 μm or less, the average aspect ratio is more preferably 50 or more, and the average particle size is More preferably, it is 1 μm or less and the average aspect ratio is 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral.

  The content of the layered mineral particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added as a powder to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. It is preferable that the gel swollen in water is prepared and then added to the coating solution.

A silicate aqueous solution can also be used as another additive material for the hydrophilic layer. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer using a metal alkoxide by a so-called sol-gel method can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Published by Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.

  In the present invention, a hydrophilic organic resin may be contained in the hydrophilic layer.

  Examples of the hydrophilic organic resin include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, and acrylic. Examples thereof include resins such as polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone.

  In addition, the resin may contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, and acrylic resins having a tertiary amino group or a quaternary ammonium group. , Diacrylamine and the like. The cationic resin may be added in the form of fine particles. Examples thereof include a cationic microgel described in JP-A-6-161101.

  As a more preferred embodiment of the present invention, the hydrophilic organic resin contained in the hydrophilic layer is water-soluble, and at least part of the hydrophilic organic resin remains in a water-soluble state and exists in a state that can be eluted in water. Can be mentioned.

  As the water-soluble material contained in the hydrophilic layer, saccharides are preferable.

  As the saccharide, an oligosaccharide, which will be described in detail later, can be used, but it is particularly preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred.

  This is because an effect of forming the surface shape of the hydrophilic layer in a preferable state can be obtained by including the polysaccharide in the hydrophilic layer.

  The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 50 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention.

  Such a concavo-convex structure can be formed by containing an appropriate amount of a filler having an appropriate particle size in the hydrophilic layer, but the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble substance are used in the hydrophilic layer coating solution. It is preferable that a structure having better printing performance can be obtained by containing a polysaccharide and forming a phase separation when the hydrophilic layer is applied and dried.

  The shape of the concavo-convex structure (such as pitch and surface roughness) is the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, the solid content concentration of the coating solution, and the wet film. The thickness and drying conditions can be appropriately controlled.

  The pitch of the concavo-convex structure is more preferably 0.2 to 30 μm, and further preferably 0.5 to 20 μm. Further, a concavo-convex structure having a multiple structure in which a concavo-convex structure having a smaller pitch is formed on the concavo-convex structure having a large pitch may be formed.

  As surface roughness, 100-1000 nm is preferable by Ra, and 150-600 nm is more preferable.

  Moreover, as a film thickness of a hydrophilic layer, it is 0.01-50 micrometers, Preferably it is 0.2-10 micrometers, More preferably, it is 0.5-3 micrometers.

  In addition, the hydrophilic layer coating solution for forming the hydrophilic layer of the present invention may contain a water-soluble surfactant for the purpose of improving the coating property. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains.

  The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

  In addition, the hydrophilic layer can contain a phosphate. In the present invention, since the hydrophilic layer coating solution is preferably alkaline, the phosphate is preferably added as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening at the time of printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

  A preferred embodiment in the case of providing a hydrophilic layer by hydrophilizing the surface of the substrate is a case where an aluminum substrate is used. Since the hydrophilic layer is provided on the aluminum substrate, the surface is roughened and used.

  Prior to roughening (graining treatment), it is preferable to perform a degreasing treatment in order to remove the rolling oil on the surface. As the degreasing treatment, a degreasing treatment using a solvent such as trichlene or thinner, an emulsion degreasing treatment using an emulsion such as kesilon or triethanol, or the like is used. In addition, an alkaline aqueous solution such as caustic soda can be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed only by the degreasing treatment can be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is generated on the surface of the support. It is preferable to perform the treatment. Examples of the roughening method include a mechanical method and a method of etching by electrolysis.

  The mechanical roughening method used is not particularly limited, but a brush polishing method and a honing polishing method are preferable.

  The electrochemical surface roughening method is not particularly limited, but a method of electrochemical surface roughening in an acidic electrolyte is preferable.

After the surface is roughened by the electrochemical surface roughening method, it is preferably immersed in an acid or alkali aqueous solution in order to remove aluminum scraps on the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an alkaline aqueous solution. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. In addition, it is preferable that after the immersion treatment with an alkaline aqueous solution, neutralization treatment is performed by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

  The mechanical surface roughening method and the electrochemical surface roughening method may each be used alone for roughing, or the mechanical surface roughening method followed by the electrochemical surface roughening method. You may roughen.

  Following the roughening treatment, an anodic oxidation treatment can be performed. There is no restriction | limiting in particular in the method of the anodizing process which can be used in this invention, A well-known method can be used. By performing the anodizing treatment, an oxide film is formed on the support.

  The anodized support may be sealed as necessary. These sealing treatments can be performed using known methods such as hot water treatment, boiling water treatment, water vapor treatment, sodium silicate treatment, dichromate aqueous solution treatment, nitrite treatment, and ammonium acetate treatment.

  Furthermore, after performing these treatments, a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt (for example, zinc borate) or Also suitable are those coated with a yellow dye, amine salt or the like. Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A No. 5-304358 is covalently used.

(Protective layer)
A protective layer may be provided on the heat-sensitive image forming layer according to the present invention.

  As a material used for the protective layer, the above-mentioned water-soluble resin and water-dispersible resin can be preferably used.

  Further, hydrophilic overcoat layers described in JP-A Nos. 2002-19318 and 2002-86948 can also be preferably used.

The amount per the protective layer is 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.

(Image exposure)
The printing plate material of the present invention is image-exposed with a laser beam in accordance with image data, and then mounted on a printing machine and developed on-machine as necessary to obtain a printing plate, which is used for printing.

  More specifically, the image exposure is preferably scanning exposure using a laser that emits light in the infrared and / or near infrared region, that is, in the wavelength range of 700 to 1500 nm.

  Although a gas laser may be used as the laser, it is particularly preferable to perform scanning exposure using a semiconductor laser that emits light in the near infrared region.

  As an apparatus suitable for scanning exposure, any apparatus may be used as long as it can form an image on the surface of the printing plate material in accordance with an image signal from a computer using a semiconductor laser.

  In general, (1) a method of exposing the entire surface of the printing plate material by performing two-dimensional scanning using one or a plurality of laser beams on the printing plate material held by the flat plate holding mechanism; ) A printing plate material held along a cylindrical surface inside a fixed cylindrical holding mechanism, and using one or more laser beams from the inside of the cylinder in the circumferential direction of the cylinder (main scanning direction) A method in which the entire surface of the printing plate material is exposed by moving in a direction perpendicular to the circumferential direction (sub-scanning direction) while scanning, and (3) printing held on the surface of a cylindrical drum that rotates about an axis as a rotating body The plate material is printed by moving in the direction perpendicular to the circumferential direction (sub-scanning direction) while scanning in the circumferential direction (main scanning direction) by rotating the drum using one or more laser beams from the outside of the cylinder. A method that exposes the entire plate material That.

  The heat-sensitive image forming layer according to the present invention is an on-press developable layer, and the non-image area is removed on the printing press using dampening water and / or ink.

  The non-image portion of the image forming layer on the printing machine is removed by using a dampening water supply roller (hereinafter also referred to as a watering roller) or an ink supply roller (hereinafter also simply referred to as an ink roller) while rotating the plate cylinder. Although it can be carried out by contact with the exposed printing plate material, it can be carried out by various sequences such as those exemplified below or other than that.

  In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.

  (1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, then an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then Start printing.

  (2) As a sequence for starting printing, an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, then a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then Start printing.

  (3) As a sequence for starting printing, the water roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder by one to several tens of rotations, and then printing is started.

(Printer)
In the present invention, a known lithographic printing machine having a member for supplying dampening water and a member for supplying ink on the printing plate surface can be used as the printing machine.

  The dampening water according to the present invention can be used in either a dampening water supply system or a continuous water supply dampening water supply apparatus, but is particularly preferably used in a continuous water supply dampening water supply apparatus.

  It can also be used in printing presses such as Mitsubishi Diamatic Dumpner, Comorimatic, Dahlglen Dampner and Heidelberg Alcolor Dumpner.

(Printing ink)
The ink that can be used in the printing according to the present invention may be any ink that can be used in lithographic printing. Specifically, rosin-modified phenolic resin and vegetable oil (linseed oil, tung oil, soybean oil, etc.) , Oil-based inks composed of components such as petroleum solvents, pigments, oxidation polymerization catalysts (cobalt, manganese, lead, iron, zinc, etc.), and ultraviolet rays composed of components such as acrylic oligomers, acrylic monomers, photopolymerization initiators, and pigments Examples thereof include curable UV inks and hybrid inks having both the properties of oil-based inks and the properties of UV inks.

  In the present invention, the case where an oxidation polymerization drying type printing ink is included as the printing ink is particularly preferably used from the viewpoint of printing durability.

  Oxidation polymerization type ink is a dry film obtained by oxidative polymerization of dry oil (linseed oil or other oil having a double bond in the molecule) contained in the ink with oxygen in the air. It contains an oxidative polymerization accelerator called a dryer for accelerating polymerization.

  By containing an oxidative polymerization accelerator, the time from the ink adhering to the paper surface to drying and solidifying can be shortened, and the work time can be shortened by preventing the set-off and quickly moving to the next process. Various advantages can be obtained. Since the polyvalent metal salt particles of the carboxylic acid compound contained in the printing plate material of the present invention also function as the oxidative polymerization accelerator described above, when printing is performed using the oxidative polymerization ink, It is presumed that the obtained ink is oxidatively polymerized on the surface of the image area to form a strong film, which reinforces the image area and greatly improves the printing durability.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

(Preparation of substrate 1)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm was immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolved amount became 2 g / m ² , and washed with water. Then, it was immersed in 0.1 mass% hydrochloric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water.

Next, this aluminum plate was subjected to an electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was.

The distance between the electrode and the sample surface at this time was 10 mm. The electrolytic surface-roughening treatment was divided into 10 times, and the electric energy for one treatment (at the time of anode) was set to 30 C / dm ² , so that the electric energy for treatment was 300 C / dm ^{2 in} total (at the time of anode).

  In addition, a rest period of 5 seconds was provided between each surface roughening treatment.

After electrolytic surface roughening, it is immersed in a 1% by weight sodium hydroxide aqueous solution maintained at 50 ° C. and etched so that the amount of dissolution including the smut of the roughened surface becomes 1.2 g / m ^2. Then, it was washed with water, then immersed in a 10% aqueous sulfuric acid solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water.

Next, anodization was performed in a 20% sulfuric acid aqueous solution so that the amount of electricity was 150 C / dm ² under a constant voltage condition of 20 V, followed by washing with water.

  Next, after squeezing the surface water after washing with water, it was immersed in a 0.5% by mass disodium hydrogenphosphate aqueous solution maintained at 70 ° C. for 30 seconds, washed with water and then dried at 80 ° C. for 5 minutes. Material 1 was obtained.

  Ra of the substrate 1 was 350 nm (measured at 40 times using RST Plus manufactured by WYKO).

(Preparation of base material 2)
A biaxially stretched polyester film film having a thickness of 175 μm is subjected to a corona discharge treatment of 8 W / m ² · min on one side, and then the following undercoat coating solution a is applied to one side so that the dry film thickness becomes 0.8 μm. After coating, undercoating liquid b was applied to a dry film thickness of 0.1 μm while performing corona discharge treatment (8 W / m ² · min), and dried at 180 ° C. for 4 minutes (undercoating surface A). ).

Also, after coating the following undercoat coating solution c on the opposite side so as to have a dry film thickness of 0.8 μm, the undercoat coating solution d is dried film thickness 1 while performing corona discharge treatment (8 W / m ² · min). The coating was applied to a thickness of 0.0 μm and dried at 180 ° C. for 4 minutes (undercoating surface B).

After coating, the surface electrical resistance at 25 ° C. and relative humidity of 25% RH was 10 ⁸ Ω. Thus, the base material 2 which formed the undercoat layer on both surfaces was obtained.

<< Undercoat coating liquid a >>
Ternary copolymer latex of styrene / glycidyl methacrylate / butyl acrylate = 60/39/1 (molar ratio) (Tg = 75 ° C.) (based on solid content) 6.3 parts Styrene / glycidyl methacrylate / butyl acrylate = 20/40 / 40 (molar ratio) ternary copolymer latex 1.6 parts Anionic surfactant S-1 0.1 part Water 92.0 parts << Undercoat coating liquid b >>
Gelatin 1 part Anionic surfactant S-1 0.05 part Hardener H-1 0.02 part Matting agent (silica, average particle size 3.5 μm) 0.02 part Antifungal agent F-1 0.01 Water 98.9 parts

<< Undercoat coating liquid c >>
Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 (molar ratio) terpolymer latex (based on solid content) 0.4 part Styrene / glycidyl methacrylate / butyl acrylate / acetoacetoxyethyl methacrylate = 39/40 / 20/1 (molar ratio) quaternary copolymer latex
7.6 parts anionic surfactant S-1 0.1 part water 91.9 parts << undercoat coating solution d >>;
Conductive composition of component d-1 / component d-2 / component d-3 = 66/31/1
6.4 parts Hardener H-2 0.7 parts Anionic surfactant S-1 0.07 parts Matting agent (silica, average particle size 3.5 μm) 0.03 parts Water 92.8 parts Component d- 1;
An anionic polymer compound comprising a copolymer of sodium styrenesulfonate / maleic acid = 50/50; component d-2;
Three-component copolymer latex consisting of styrene / glycidyl methacrylate / butyl acrylate = 40/40/20 component d-3;
Polymeric activator comprising styrene / sodium isoprenesulfonate = 80/20

(Production of fatty acid polyvalent metal salt particles)
Zn naphthenate particles Zn naphthenate powder: 40 parts by mass, polyoxyethylene dodecyl ether: 2 parts by mass, pure water: 58 parts by mass are mixed using a zirconia bead (0.3 mm diameter) with a sand grinder. went.

  Dispersion was carried out for 4 hours to obtain a Zn naphthenate particle dispersion having an average particle size of 0.3 μm and a solid content of 42% by mass.

Zn octenoate particles In the same manner as above except that Zn naphthenate was changed to Zn octenoate, a Zn octenoate particle dispersion having an average particle size of 0.3 μm and a solid content of 42 mass% was obtained.

(Preparation of unprocessed printing plate material)
Preparation of coating solution 1
Each material of the lower layer 1, the lower layer 2 and the upper layer 1 having the composition shown below was sufficiently mixed and stirred and filtered to prepare each coating solution.
Coating solution composition for lower layers 1 and 2 (solid content: 25% by mass) (numerical values not indicated in the table indicate parts by mass)

  Coating solution composition for upper layer 1 (solid content: 10% by mass) (Numerical values not shown in the table indicate parts by mass)

<Preparation of printing plate material 1>
The lower layer 1 was applied onto the roughened surface of the substrate 1 using a wire bar so that the dry weight was 5 g / m ² and dried at 60 ° C. for 2 minutes.

Next, the upper layer 1 was applied onto the lower layer 1 using a wire bar so that the dry weight was 0.3 g / m ² and dried at 60 ° C. for 2 minutes.

  Further, an aging treatment was performed at 55 ° C. for 48 hours to obtain a printing plate material 1.

<Preparation of printing plate material 2>
A printing plate material 2 was obtained in the same manner as the printing plate material 1 except that the lower layer 1 of the printing plate material 1 was changed to the lower layer 2.

  The printing plate materials 1 and 2 become an ink-imparting image area by melting the wax (and Zn naphthenate (printing plate material 1)) in the lower layer by exposure and leaching onto the surface of the hydrophilic image forming layer. Negative version.

  Each printing plate material was exposed by an infrared laser as follows.

[Exposure method]
The printing plate material was wound around and fixed to an external exposure drum with the image forming layer facing outside. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm is used for exposure, and an image is formed with 175 lines at 2400 dpi (dpi represents the number of dots per 2.54 cm) under the condition that the exposure energy is 250 mJ / cm ^2. did.

  The exposed image includes a solid image and a 1 to 99% halftone dot image.

  Next, using these printing plate materials, printing and evaluation were performed under the following conditions.

[Printing method]
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., 2% by mass of ASTROMARK 3 (manufactured by Nikken Chemical Laboratories) as fountain solution, ink is an oxidation polymerization type ink, manufactured by Toyo Ink Toyo King High Unity M Red was used.

  For the printing paper, coated paper was used from the first printing to 100 sheets, and high quality paper (Shiraoi) was used thereafter.

  The exposed printing plate material was attached to the plate cylinder of a printing press, and printing was performed with the same printing sequence as that of the PS plate. Printing was performed up to 20,000 sheets.

[Evaluation of printability]
Up to 1 to 100 printed materials were observed after printing, and printing performance was evaluated.

  Printing that is free of stains in the non-image area, has a solid density of 1.5 or more, and has a 90% halftone dot image, in which ink is deposited on the non-image area, so-called no ink color is obtained. The number of sheets was used as an index of printability. The results are shown in Table 3.

[Evaluation of printing durability]
The printed matter was sampled every 1000 sheets, and the image quality of the 3% halftone dot image portion and the solid image portion was evaluated.

  For the 3% halftone dot image portion, the point at which halftone dot breakage was 30% or more when observed with a loupe was defined as the printing end point, and the number of printed sheets was defined as the number of printed sheets.

  With respect to the solid image portion, the printing end point was determined when the blur was confirmed visually, and the number of printed sheets was defined as the number of printed sheets. The results are shown in Table 3.

  From Table 3, it can be seen that the printing plate material of the present invention is excellent in printing performance and printing durability.

<Preparation of on-press development type printing plate material Preparation of coating solution 2
Each material of the lower layer 3, the hydrophilic layer 2, and the heat-sensitive image forming layers 1 to 3 having the composition shown below was sufficiently mixed and stirred, and filtered to prepare each coating solution.

  Coating solution composition for lower layer 3 (solid content 20% by mass) (numerical values not shown in the table indicate parts by mass)

  Coating solution composition for hydrophilic layer 2 (solid content: 30% by mass) (numerical values not shown in the table indicate parts by mass)

  Coating composition for heat-sensitive image forming layer, (numerical values not shown in the table indicate parts by mass)

<Preparation of printing plate material 3>
The lower layer 3 was applied and formed on the undercoat A surface of the substrate 2. The application was performed using a wire bar and dried at 120 ° C. for 2 hours. The dry weight of the undercoat layer was 2.0 g / m ² .

Next, the coating liquid for hydrophilic layer 2 was applied onto the undercoat layer of the substrate 2 on which the undercoat layer was formed using a wire bar, and dried at 120 ° C. for 3 minutes. The drying amount of the hydrophilic layer 2 was set to 6 g / m ² .

  Next, an aging treatment at 60 ° C. for 48 hours was performed.

  The coating solution for image forming layer 1 was applied on the hydrophilic layer after the aging treatment using a wire bar and dried at 55 ° C. for 3 minutes.

The dry weight of each image forming layer was 0.3 g / m ² . Next, an aging treatment was performed at 55 ° C. for 24 hours to obtain a printing plate material 3.

<Preparation of printing plate materials 4 and 5>
Printing plate materials 4 and 5 were obtained in the same manner as the printing plate material 3 except that the thermal image forming layer 1 was changed to the thermal image forming layers 2 and 3.

  The exposure was performed in the same manner as in the case of the printing plate material 1.

  Printing was performed in the same manner as for the printing plate material 1 except that the number of printed sheets was 50,000.

  Printing evaluation was performed in the same manner as in the case of the printing plate material 1. The results are shown in Table 7.

  From Table 7, even if the printing plate material of the present invention is an on-press development type, it has good printing durability without impairing printability, and is excellent in printing performance and printing durability. I understand that.

Claims (7)

A printing plate material having a hydrophilic thermosensitive image forming layer whose surface is oleophilic on heating on a substrate, the hydrophilic thermosensitive image forming layer containing polyvalent metal salt particles of a carboxylic acid compound Printing plate material characterized by. A printing plate material having a heat-sensitive image forming layer that can be developed on-press on a substrate, wherein the heat-sensitive image forming layer contains polyvalent metal salt particles of a carboxylic acid compound. A printing method comprising: exposing an image of the printing plate material according to claim 1 or 2 and printing using an oxidation polymerization drying type printing ink. The printing plate material according to claim 1, wherein the hydrophilic thermosensitive image forming layer contains a thermally polymerizable compound or a thermally crosslinkable compound. The printing plate material according to claim 2, wherein the heat-sensitive image forming layer contains a thermally polymerizable compound or a thermally crosslinkable compound. The printing plate material according to claim 1, wherein the hydrophilic thermosensitive image forming layer contains a thermally crosslinkable wax and a crosslinking agent. The printing plate material according to claim 2, wherein the heat-sensitive image forming layer contains a heat-crosslinking wax and a crosslinking agent.