JP2007276195A - Lithographic printing plate material and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate material which improves in printing failures such as a development fault and void, prevents marring of a plate surface by foreign matter and staining of printed matter, on the occasion of printing of a printing plate, and has the same operability as conventional ones, and a printing method. <P>SOLUTION: In this lithographic printing plate material, the average particle diameter of a pigment contained in a hydrophilic layer is 0.1-1.0 μm and the average particle diameter of inorganic particles or particles coated with an inorganic material, other than the pigment, is 0.5-10 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a planographic printing plate material (hereinafter also simply referred to as a printing plate material) and a printing method, and more specifically, contains a titanium black pigment on the image layer side, is a computer-to-plate (CTP) system, The present invention relates to a lithographic printing plate material having a developability and a printing method.

  With the digitization of print data, there is a need for CTPs that are inexpensive, easy to handle, and have the same printability as PS plates. In particular, in recent years, a general-purpose thermal processless printing plate that can be applied to a printing press that has a direct imaging (DI) function and that does not require a special chemical development process, and has the same usability as a PS plate. Expectations are growing.

  In recent years, so-called processless printing plates that do not require development processing have been put into practical use as printing plate materials.

  For example, JP-A-7-1849, JP-A-7-164773, JP-A-9-123387, and JP-A-10-193823 disclose processless printing plates.

  These processless printing plates do not require an automatic development processor, and can be directly printed on a printing machine after being exposed by a plate setter.

  However, it is difficult for such a printing plate material to give sufficient energy to cure the image forming layer, so that the hardness of the image forming layer is weakened, and the plate surface is easily damaged by impact and foreign matter. Therefore, it has been pointed out that it is weak against scratches during handling compared to PS plates and thermal plates that have been used conventionally.

In order to improve this point, a photothermal conversion layer containing a compound that converts laser light into heat and a hydrophilic layer containing a hydrophilic polymer cross-linked with a metal chelate compound are sequentially laminated on a support. A technique (for example, see Patent Document 1), a technique having an overcoat layer containing water-soluble celluloses on a hydrophilic image forming layer (for example, see Patent Document 2), a hydrophobizing precursor Techniques having a hydrophilic heat-sensitive layer and a hydrophobic overcoat layer (see, for example, Patent Document 3) are disclosed, but these scratch improvement methods are still not sufficient, and workability equivalent to that of conventional printing plates There was a problem that it did not reach the scratch resistance.
JP 2001-92115 A JP 2002-19318 A JP 2004-237605 A

  An object of the present invention is to improve a printing failure such as development failure or white spot, prevent a scratch on a printing plate due to foreign matter during printing of a printing plate, and prevent a printed matter from being stained, and a printing plate material and printing having workability equivalent to the conventional one It is to provide a method.

  The above object of the present invention has been achieved by the following constitution.

  1. The average particle size of the pigment contained in the hydrophilic layer is 0.1 μm to 1.0 μm, and the average particle size of the inorganic particles other than the pigment or particles coated with an inorganic material is 0.5 μm to 10 μm. Planographic printing plate material.

  2. 2. The melting point of the hot-melt particles contained in the image forming layer is 60 ° C. to 100 ° C., and the content in the solid content in the image forming layer is 70% by mass to 95% by mass. Lithographic printing plate material.

  3. 3. A printing method comprising printing using the printing plate material according to 1 or 2 having on-press developability.

  According to the present invention, by using a printing plate material that is a CTP method and has on-machine developability, the productivity is improved as compared with the conventional printing plate, and the printing plate such as a conventional PS plate is handled without any change. It is possible to improve printing failures such as development defects and white spots, prevent scratches on the plate surface due to foreign matter during printing of the printing plate, and stains on the printed matter.

  Hereinafter, the present invention will be described in more detail.

  The printing plate material of the present invention is a printing plate material that can be developed on a printing machine by coating an image forming layer on an aluminum base material or polyester resin that has been roughened on one side.

  The on-press development in the present invention means that when printing is performed with an exposed printing plate material attached to a normal offset printing press, the printing plate material is not removed by the action of dampening water and printing ink applied to the plate surface. This means that the image forming layer in the exposed area is selectively removed at the beginning of printing.

[Support]
(Aluminum substrate)
As a base material of this invention, the well-known aluminum material used as a board | substrate of a printing plate can be used. 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.

  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.

  It is common to use a roughened aluminum plate. The surface of the aluminum plate is roughened by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening the surface, and a method of selectively dissolving the surface chemically. By the method. As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used.

  Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte.

  Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.

  The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm ^2. A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. The amount of the anodized film is preferably 1 to 10 g / m ² . When the amount is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image part of the lithographic printing plate is easily scratched, and so-called “scratch stain” in which ink adheres to the scratched part during printing. It tends to occur.

  By performing such a surface roughening treatment, the adhesion between the aluminum substrate and the hydrophilic layer is improved, and the printing durability can be increased.

  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.

(Polyester base material)
The biaxially stretched polyester film constituting the preferred support for a photothermographic material of the present invention is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate (PAr) or the like. Among them, more preferred polyesters are PET and PEN, and particularly preferred is PET. What is comprised here may be a copolymer and a polymer blend, and refers to the thing whose mass ratio of the component to the whole is 50 mass% or more.

PET is composed of terephthalic acid and ethylene glycol, and PEN is composed of naphthalene dicarboxylic acid and ethylene glycol, which can be polymerized by combining them in the presence of a catalyst under suitable reaction conditions. At this time, you may mix an appropriate 1 type, or 2 or more types of 3rd component. The suitable third component may be any compound having a divalent ester-forming functional group. Examples of the dicarboxylic acid include the following.
Isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethane dicarboxylic acid, cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl Examples thereof include ketone dicarboxylic acid and phenylindane dicarboxylic acid.

  Examples of glycols include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, and bis. (4-Hydroxyphenyl) sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like can be mentioned.

  The intrinsic viscosity of the PET resin and film of the present invention is preferably 0.5 to 0.8. Moreover, you may mix and use what has a different intrinsic viscosity.

  The method for synthesizing the PET of the present invention is not particularly limited, and can be produced according to a conventionally known method for producing PET. For example, a direct esterification method in which a dicarboxylic acid component is directly esterified with a diol component. First, a dialkyl ester is used as a dicarboxylic acid component, this is transesterified with the diol component, and this is heated under reduced pressure. A transesterification method of polymerizing by removing excess diol component can be used. At this time, if necessary, a transesterification catalyst or a polymerization reaction catalyst can be used, or a heat-resistant stabilizer can be added. Examples of the heat stabilizer include phosphoric acid, phosphorous acid, and ester compounds thereof.

  In addition, anti-coloring agents, crystal nucleating agents, slipping agents, stabilizers, anti-blocking agents, UV absorbers, viscosity modifiers, clearing agents, antistatic agents, pH adjusters, dyes, pigments, etc. May be added.

  The thickness of the support for a photothermographic material of the present invention is not particularly limited, but is preferably 100 to 250 μm, particularly preferably 150 to 200 μm from the viewpoint of ease of handling.

[Configuration of image forming layer surface]
The configuration on the image forming side of the present invention is composed of a plurality of layers, and is basically composed of a lower layer, a hydrophilic layer, and an image forming layer from the substrate side. The structure of each layer will be described below.

(Photothermal conversion agent)
The present invention is characterized in that a black pigment is contained in the hydrophilic layer as a photothermal conversion agent. Specific examples of the pigment include titanium-based TiO ₂ and TiO ₂ reduced from TiO ₂ (titanium oxynitride, generally titanium black), and examples of the iron oxide-based pigment include FeO and Fe ₃ O ₄ . Further, a pigment of particles in which titanium and iron are mixed is also preferable. In the present invention, these particle sizes are 0.1 μm or more and 1.0 μm or less.

  These pigments are colored with respect to the amount added, that is, they have good photothermal conversion efficiency. 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, these composite metal oxide particles may be dispersed by a known method before being added to the layer coating solution to form a dispersion (paste).

  A dispersing agent can be used for dispersion as needed. A well-known thing can be used as a dispersing agent. 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 pigment particles.

  The amount of these pigments to be added is 20% or more and less than 50%, more preferably 25% or more and less than 45%, more preferably 25% or more and less than 40%, based on the total solid content of the hydrophilic layer. is there. When the addition amount is less than 20%, sufficient sensitivity cannot be obtained, and when it is 50% or more, the pigment falls off.

  The following infrared absorbing dye can be added as a photothermal conversion material to the hydrophilic layer and the image forming layer.

  General infrared absorbing dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, organic compounds such as phthalocyanine dyes and naphthalocyanine dyes , Azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-1-280750, JP-A-1-293342, JP-A-2-2074, Kaihei 3-26593, JP-A-3-30991, JP-A-3-34891, JP-A-3-36093, JP-A-3-36094, JP-A-3-36095, JP-A-3-42281, JP-A-3-42281 Examples thereof include compounds described in JP-A-3-97589, JP-A-3-103476, and the like. These can be used alone or in combination of two or more.

  The addition amount of these infrared absorbing dyes is 0.1% or more and less than 10%, more preferably 0.3% or more and less than 7%, more preferably 0.5%, based on the total solid content of the image forming layer. The range is less than 6%. If the addition amount deviates from this, as described above, if the addition amount is less than 0.1%, sufficient sensitivity cannot be obtained, and if it is 10% or more, ablation residue due to ablation occurs.

(Hydrophilic layer)
In the present invention, materials used for the hydrophilic layer include the following.

  The material forming the hydrophilic matrix is preferably a metal oxide, more preferably metal oxide fine particles.

Examples include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The metal oxide may have any shape such as a spherical shape, a feather shape, and the like, and the average particle size is 3 to 100 nm. However, several kinds of metal oxide fine particles having different average particle diameters can be used in combination. Further, the surface of the particles may be subjected to a surface treatment.
The metal oxide 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 can provide good strength.

  The colloidal silica preferably includes a necklace-shaped colloidal silica, which will be described later, and a 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 the water dispersion diameter of spherical silica whose primary particle diameter is on the order of nm.

  The necklace-shaped colloidal silica used in the present invention means “pearl necklace-shaped” 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.

  A pearl necklace shape (that is, a pearl necklace shape) means that an image in a state in which silica particles of colloidal silica are joined together and connected is shaped 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.

  As product names, “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 linked 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 hydrophilic layer matrix. Among these, when alkaline “Snowtex PS-S”, “Snowtex-PS-M” and “Snowtex-PS-L” 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.

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

  Alkaline colloidal silica with an average particle size in this range Nissan Chemical's “Snowtex 20 (particle size 10-20 nm)”, “Snowtex-30 (particle system 10-20 nm)”, “Snowtex-40 (particles) "Snowtex-N (particle diameter 10-20 nm)", "Snowtex-S (particle diameter 8-11 nm)", "Snowtex-XS (particle diameter 4-6 nm)". It is done.

  Colloidal silica having an average particle size of 20 nm or less is particularly preferred because it can be further improved in strength while maintaining the porosity of the layer when used in combination with the aforementioned necklace-shaped 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, more preferably 70/30 to 20/80, and still more preferably 60/40 to 30/70.

  Moreover, the hydrophilic layer matrix of the printing plate material of the present invention can contain layered clay mineral particles. 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 the size of the flat lamellar mineral particles, the average particle diameter (maximum length of the particles) is less than 1 μm in the state of being contained in the layer (including the case where the swelling process and the dispersion peeling process have been performed). The aspect ratio is preferably 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. When the particle diameter is larger than the above range, the coating film may be non-uniform, and the strength may be locally reduced. On the other hand, when the aspect ratio is not more than the above range, the number of tabular grains with respect to the addition amount is reduced, the viscosity is insufficient, and the effect of suppressing sedimentation of the particulate matter is reduced.

  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. After the gel swollen in water is prepared, it is preferably added to the coating solution.

A silicate aqueous solution can also be used as another additive material in the hydrophilic layer matrix of the present invention. 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.

  Moreover, you may contain water-soluble resin. Water-soluble resins include polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic Examples thereof include resins such as polymer polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone. However, it is preferable to use a polysaccharide as the water-soluble resin used in the present invention.

  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 20 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention.

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

  The hydrophilic layer coating solution of the present invention may contain a water-soluble surfactant for the purpose of improving coating properties. 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 of the present invention 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 during 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.

  The present invention is characterized by containing inorganic particles having a particle diameter of 0.5 μm or more and 10 μm or less or particles coated with an inorganic material. These particles are used as a mat material. By using the mat material under these conditions, the surface shape of the hydrophilic layer and the filling degree of the hydrophilic layer matrix can be controlled.

The inorganic particles or particles coated with an inorganic material may be used regardless of whether they are porous or non-porous. As inorganic fillers, silica, alumina, zirconia, titania, carbon black, graphite, TiO ₂ , BaSO ₄ , ZnS MgCO ₃ , CaCO ₃ , ZnO, CaO, WS ₂ , MoS ₂ , MgO, SnO ₂ , Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, SiC, CeO ₂ , BN, SiN, MoC, BC , WC, titanium carbide, corundum, artificial diamond, garnet, garnet, quartzite, triboli, diatomaceous earth, dolomite, etc. In addition, as inorganic clothing fillers, organic particles such as PMMA, polystyrene, and melamine are made from core particles. Also, particles coated with small relay inorganic particles can be mentioned. The particle size of the inorganic particles is preferably about 1/10 to 1/100 of the core particles.

  As the inorganic particles, similarly known metal oxide particles such as silica, alumina, titania, zirconia can be used. As the coating method, various known methods can be used, but the core material particles and the coating material particles are collided at high speed in the air like a hybridizer to cause the coating material particles to bite into the surface of the core material particles. A dry coating method of fixing and coating can be preferably used.

In the present invention, any filler that satisfies the scope of the present invention can exert its effect without any particular limitation. In particular, in order to suppress sedimentation in the coating solution, porous silica particles, porous aluminosilicate particles, etc. It is preferable to use a porous inorganic filler and a porous inorganic filler.
When the particle size is less than 0.5 μm, it becomes difficult to control the surface shape of the hydrophilic layer and the filling degree of the hydrophilic layer matrix, and the blanket stains are deteriorated. On the other hand, when the particle diameter exceeds 10 μm, the resolution of image formation is lowered.

  The average particle size of the inorganic particles or the particles coated with the inorganic material is more preferably 0.7 μm or more and 5 μm or less. As addition amount, it is preferable that it is 1-50 mass% of the whole hydrophilic layer, and it is more preferable that it is 5-40 mass%.

(Underlayer)
As a form of the present invention, a lower layer may be provided.
When a lower layer is provided, the same material as the hydrophilic layer can be used as the material used for the lower layer.

  However, the lower layer is less advantageous in that it is porous, and the nonporous material improves the coating strength, so the content of the porous material of the hydrophilic matrix is higher than that of the hydrophilic layer. Is preferably less, more preferably not contained.

  When particles having a particle size of 1 μm or more are contained, the amount of particles added is preferably 1 to 50% by mass, and more preferably 5 to 40% by mass of the entire lower layer.

  Similarly to the hydrophilic layer as the entire lower layer, a low content ratio of materials containing carbon such as organic resin and carbon black is preferable for improving hydrophilicity, and the total of these materials is less than 9% by mass. It is preferable that it is less than 5% by mass.

(Image forming layer)
The image forming layer of the present invention has a melting point of 60 ° C. or higher and 100 ° C. or lower as heat-meltable and / or heat-fusible fine particles, and a solid content of 70% by mass or more and 95% by mass or less. It is characterized by that.

  The heat-meltable fine particles used in the present invention are fine particles formed of a material that has a low viscosity when melted, and is generally classified as a wax, among thermoplastic materials. When the melting point is less than 50 ° C., storage stability is a problem, and when the melting point is higher than 100 ° C., the adhesion to the hydrophilic layer 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, fatty acid amide, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, high-sensitivity 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 fine particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm. When the average particle size is smaller than 0.1 μm, when the coating solution for the layer containing the heat-meltable fine particles is applied onto the porous hydrophilic layer described later, the heat-meltable fine particles are not removed from the pores of the hydrophilic layer. It becomes easy to enter inside or into the gaps between fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, which may cause scumming. When the average particle size of the heat-meltable fine particles is larger than 10 μm, the resolution is lowered.

  Further, the composition of the heat-meltable fine 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 heat-meltable microparticles | fine-particles in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of the heat-fusible fine particles of the present invention include thermoplastic hydrophobic polymer fine particles, and there is no specific upper limit for the softening temperature of the thermoplastic hydrophobic high-molecular polymer particles, but the temperature is high. It is preferably lower than the decomposition temperature of the coalesced fine particles. 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 constituting 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 etc. of polymers 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 polymer polymer fine particles may be composed of a polymer polymer polymerized by any known method such as emulsion polymerization, suspension polymerization, solution polymerization, and gas phase polymerization. As a method of microparticulating a polymer polymer polymerized by a solution polymerization method or a gas phase polymerization method, a method of spraying a solution in an organic solvent of the polymer polymer into an inert gas and drying to form particles, Examples thereof include a method in which a high molecular weight polymer is dissolved in a water-immiscible organic solvent, this solution is dispersed in water or an aqueous medium, and the organic solvent is distilled off to form fine particles. In any of the methods, a surfactant, such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyethylene glycol, or a water-soluble resin, such as polyvinyl alcohol, is used as a dispersant or stabilizer in polymerization or micronization as necessary. May be used.

  The thermoplastic fine 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. When the average particle size is smaller than 0.01 μm, when the coating liquid for the layer containing the heat-meltable fine particles is applied onto the porous hydrophilic layer described later, the heat-meltable fine particles are not removed from the pores of the hydrophilic layer. It becomes easy to enter inside or into the gaps between fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, which may cause scumming. When the average particle size of the heat-meltable fine particles is larger than 10 μm, the resolution is lowered.

  The thermoplastic fine particles may be continuously changed in composition between the inside and the surface layer, or may be coated with different materials.

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.

  The image-forming functional layer containing the heat-fusible and / or heat-fusible fine particles of the present invention can further contain a water-soluble material. By including the water-soluble material, when the image forming functional layer in the unexposed area is removed using dampening water or ink on the printing press, the removability can be improved.

  As the water-soluble material, the water-soluble resins mentioned as materials that can be contained in the hydrophilic layer can also be used. However, as the image forming functional layer of the present invention, it is preferable to use saccharides, particularly oligosaccharides. Is preferred.

Since the oligosaccharide dissolves quickly in water, the image forming functional layer in the unexposed area on the printing device can be removed very quickly, and the normal PS plate printing operation can be performed without being aware of the special removal operation. Can be removed by printing in the same manner as in the above, and printing waste paper does not increase.
In addition, the oligosaccharide can maintain good printability of the hydrophilic layer without concern for lowering the hydrophilicity of the hydrophilic layer.

  An oligosaccharide is a crystalline substance that is soluble in water and generally has a sweet taste, and is obtained by dehydrating and condensing several monosaccharides by glycosidic bonds. Oligosaccharide is a kind of o-glycoside with sugar as aglycone, so it is easily hydrolyzed with acid to produce monosaccharide, and disaccharide, trisaccharide, tetrasaccharide, pentasaccharide, etc. depending on the number of molecules of monosaccharide produced are categorized. The oligosaccharide in the present invention refers to those from disaccharide to decasaccharide.

  These oligosaccharides are roughly classified into reducing oligosaccharides and non-reducing oligosaccharides depending on the presence or absence of a reducing group, and are composed of homooligosaccharides composed of a single monosaccharide and two or more types of monosaccharides. It is also classified as a hetero-oligosaccharide.

  Oligosaccharides exist naturally as free or glycosides and can also be obtained by partial hydrolysis of polysaccharides with acids or enzymes. Various oligosaccharides are also generated by glycosyl transfer by other enzymes.

  Oligosaccharides often exist as hydrates in a normal atmosphere. Moreover, the melting point differs between hydrate and anhydride.

  In the present invention, it is preferable to coat and form a saccharide-containing layer with an aqueous solution. Therefore, when the oligosaccharide is formed from an aqueous solution, if the oligosaccharide present in the layer is an oligosaccharide that forms a hydrate, its melting point. Is considered to be the melting point of the hydrate. Thus, since it has a relatively low melting point, the oligosaccharide also melts in the temperature range in which the hot melt fine particles melt or in the temperature range in which the hot melt fine particles fuse, and the porous hydrophilic layer of the hot melt fine particles It does not hinder image formation such as melt penetration into the film and fusion of heat-fused fine particles.

  Among oligosaccharides, trehalose, which is relatively high in purity, is commercially available at low cost, and despite its high solubility in water, its hygroscopicity is very low, on-press developability and storage The sex is very good.

  In addition, when oligosaccharide hydrate is melted by heat to remove water of hydration and then solidified (for a short time after solidification), it becomes an anhydrous crystal, but trehalose has a melting point of anhydride higher than that of hydrate. It is characteristic that it is higher than 100 ° C. This means that the exposed portion is melted by infrared exposure and immediately after re-solidification, the exposed portion is in a state of being difficult to melt at a high melting point, and is effective in causing image defects during exposure such as banding.

In order to achieve the object of the present invention, trehalose is particularly preferable among oligosaccharides.
As content of the oligosaccharide in a layer, 0.5-20 mass% of the whole layer is preferable, and 1-20 mass% is more preferable.

(Image forming method)
Image formation of the printing plate material of one embodiment of the present invention can be performed by heat, but it is particularly preferable to perform image formation by exposure with an infrared laser.
More specifically, exposure relating to the present invention 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. A gas laser may be used as the laser, but it is particularly preferable to use a semiconductor laser that emits light in the near infrared region.

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

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-like holding mechanism,
(2) The circumferential direction of the cylinder (main scanning direction) using one or a plurality of laser beams from the inside of the cylinder to the printing plate material held along the cylindrical surface inside the fixed cylindrical holding mechanism ), Scanning the entire surface of the printing plate material by moving it in a direction perpendicular to the circumferential direction (sub-scanning direction),
(3) A printing plate material held on the surface of a cylindrical drum that rotates about an axis as a rotator is rotated in the circumferential direction (main scanning direction) by rotating the drum using one or a plurality of laser beams from the outside of the cylinder. ) And moving in the direction perpendicular to the circumferential direction (sub-scanning direction) to expose the entire surface of the printing plate material.

  In the present invention, the scanning exposure method (3) is particularly preferable, and the exposure method (3) is used particularly in an apparatus that performs exposure on a printing apparatus.

(On-press development method and printing method)
In an image forming layer of a printing plate material using an infrared laser, which is a preferred embodiment of the printing plate material of the present invention, an infrared laser exposure portion becomes an oleophilic image portion, an unexposed portion is removed, and a hydrophilic non-image portion. Become. Although removal of the unexposed portion can be performed by washing with water, it is preferable to perform so-called on-press development in which the unexposed portion is removed using dampening water and / or ink on a printing press.

  The removal of the unexposed part of the image forming layer on the printing machine can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. The various sequences can be performed.

  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 tens of turns, then an ink roller is brought into contact with the plate cylinder to make one to several tens of turns, and then printing is performed. Start.

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

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

  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.

Example 1
<< Preparation of polyester support >>
(Preparation of support 1)
Using terephthalic acid and ethylene glycol, a polyethylene terephthalate having IV (inherent viscosity) = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) was obtained according to a conventional method.

  After pelletizing this, it is dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, rapidly cooled on a cooling drum at 50 ° C., and not yet thick enough to have an average film thickness of 175 μm after heat setting. A stretched film was prepared.

  The stretching temperature was stretched longitudinally by 1.3 times at 102 ° C. in the former stage stretching and 2.6 times at the latter stage stretching at 110 ° C. Next, it was stretched 4.5 times at 120 ° C. with a tenter. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature.

  Then, after slitting the chuck part of the tenter, knurling was performed on both ends, and after cooling to 40 ° C., the film was wound at 47.1 N / m. Thus, a biaxially stretched polyethylene terephthalate film (support 1) having a thickness of 190 μm was obtained.

  The glass transition temperature (Tg) of this biaxially stretched polyethylene terephthalate film was 79 ° C. The obtained polyethylene terephthalate film had a width (film formation width) of 2.5 m.

《Preparation of underdrawn support》
Both surfaces of the support film obtained above are subjected to a corona discharge treatment of 8 W / m ² / min, and then the following undercoat coating solution a is applied on one surface so as to have a wet film thickness of 10 μm. Later, it was dried at 180 ° C. for 4 minutes. Then, the following undercoat coating solution b was applied so as to have a wet film thickness of 11 μm while performing corona discharge treatment (8 W / m ² / min) thereon, and dried at 180 ° C. for 4 minutes. Undercoat samples 001 to 008 were obtained (undercoat surface A). Further, the following undercoat coating solution c is applied to the opposite surface so as to have a wet film thickness of 8 μm, dried at 180 ° C. for 4 minutes, and then subjected to corona discharge treatment (8 W / m ² / min). Then, the following undercoat coating solution d was applied to a wet film thickness of 5 μm and dried at 180 ° C. for 4 minutes. (Undercoat surface B).

(Undercoat coating liquid a)
Three-component copolymer latex of styrene / glycidyl methacrylate / butyl acrylate = 60/39/1, solid content 30% by mass, Tg = 75 ° C. 21.00 parts by mass Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 3 Base copolymer latex Solid content 30% by mass, Tg = 75 ° C. 5.60 parts by mass Anionic surfactant S-1 0.6 parts by mass Pure water 73.00 parts by mass (undercoat coating solution b)
Polyvinyl alcohol solid content 5% by weight, average molecular weight 1700 5.76 parts by weight Water-soluble copolyester / acryl component = 64/36 acrylic-modified polyester solid content 21.7% by weight 3.10 parts by weight Anionic surfactant S- 1 0.011 parts by weight Matting agent (silica average particle size 0.5 μm) 0.004 parts by weight Hardener H-2 0.058 parts by weight Pure water 91.06 parts by weight (undercoat coating solution c)
Tin oxide sol Solid content 8.3% by mass 10.95 parts by mass n-Butyl acrylate / styrene / glycidyl methacrylate = 40/20/40 ternary copolymer latex Solid content 30% by mass 1.51 parts by mass n-Butyl acrylate / T-butyl acrylate, styrene, hydroxymethyl methacrylate = quaternary copolymer latex of 10/35/27/28, solid content 30% by mass
0.38 parts by weight Anionic surfactant S-1 0.05 parts by weight Pure water 87.11 parts by weight (undercoat coating solution d)
Water-soluble copolyester / acryl component = 80/20 acrylic-modified polyester Solid content 17.8% by weight 14.34 parts by weight Anionic surfactant S-1 0.11 parts by weight Matting agent (silica average particle size 0.5 μm ) 0.20 parts by mass Pure water 85.35 parts by mass

(Preparation of back coating layer)
Colloidal silica: Snowtex-XS (Nissan Chemical Co., Ltd., solid content 20% by mass)
33.60 parts by mass Acrylic emulsion: DK-05 (Gifu Shellac, solid content 48% by mass)
14.00 parts by mass Matting agent (PMMA average particle size 5.5 μm) 0.56 parts by mass Pure water 51.84 parts by mass Solid content concentration 14% by mass
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a back coating layer coating solution.

Application of Back Coating Layer The coating solution for the back coating layer was applied to the undercoated surface B side by applying a corona discharge treatment of 8 W / m ² / min to the undercoated sample using wire bar # 6. Was passed through the drying zone set to 100 ° C. at a conveyance speed of 15 m / min. The amount of the back coating layer was 2.0 g / m ² .

[Preparation of lower layer coating solution]
Snowtex-XS (Nissan Chemical Co., Ltd., solid content 20% by mass) 48.10 parts by mass Snowtex-ZL (Nissan Chemical Co., Ltd., solid content 40% by mass) 1.50 parts by mass Shilton JC-40 (Mizusawa Chemical Co., Ltd.) Manufactured) 2.22 parts by mass Optobeads STM-6500S (manufactured by Nissan Chemical Co., Ltd.) 3.00 parts by mass Sodium carboxymethyl cellulose (reagent manufactured by Kanto Chemical Co., Ltd.) 0.12 parts by mass Mineral colloid MO (manufactured by Southern Clay Products) 0. 22 parts by mass Black # 3550 (manufactured by Dainichi Seika Co., Ltd., Cu-Fe-Mn series) 4.00 parts by mass Trisodium phosphate.12 water (reagent manufactured by Kanto Chemical Co., Ltd.) 0.06 parts by mass FZ-2161 (Nippon Unicar, surfactant) 0.16 parts by mass Pure water 40.62 parts by mass Solid content concentration 20% by mass
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a lower layer coating solution.

[Preparation of hydrophilic layer coating solution]
SNOWTEX-S (Nissan Chemical Co., Ltd., solid content 30% by mass) 5.2 parts by mass SNOTTEX-PSM (Nissan Chemical Co., Ltd., solid content 20% by mass) 11.7 parts by mass MP-4540M (Nissan Chemical) 4.5 parts by mass sodium carboxymethyl cellulose (reagent manufactured by Kanto Chemical Co., Ltd.) 0.12 parts by mass trisodium phosphate dodecahydrate (manufactured by Kanto Chemical Co., Ltd.) 0.06 parts by mass Shilton JC-20 (Mizusawa Chemical Co., Ltd., porous aluminosilicate particles) 1.2 parts by mass Silton AMT08 (Mizusawa Chemical Co., Ltd., porous aluminosilicate particles) 3.6 parts by mass Mineral colloid MO (manufactured by Southern Clay Products) 0 .24 parts by mass Black # 3550 (manufactured by Dainichi Seika Co., Ltd., Cu—Fe—Mn system) 4.08 parts by mass Pure water 12.3 quality Parts solid content of 30 wt%
These compositions were sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a hydrophilic layer coating solution.

Application of lower layer and hydrophilic layer Each lower layer hydrophilic layer coating solution was applied to the back surface (undercoating surface A) of the support coated with the backcoat layer using wire bar # 5, and the length of 15 m was applied. The drying zone set and pressed at 100 ° C. was passed at a conveyance speed of 15 m / min. Subsequently, the upper hydrophilic layer coating solution was applied using wire bar # 4 and passed through a drying zone set at 100 ° C. having a length of 30 m at a conveying speed of 15 m / min. The amount of each of the lower layer and the hydrophilic layer was 2.5 g / m ² and 1.6 g / m ² . The sample after coating was aged at 60 ° C. for 1 day.

[Preparation of coating solution for image forming layer]
An image layer having the following composition was applied on the upper hydrophilic layer prepared above using wire bar # 4, and a drying zone set at 70 ° C. having a length of 30 m was transported at a speed of 15 m / min. Passing through, an image forming layer was formed. The applied amount of the image forming layer was 0.55 g / m ² . The sample after application was aged at 50 ° C. for 2 days.

Carnauba wax emulsion: A118 (manufactured by Gifu Shellac Co., Ltd., average particle size 0.4 μm, melting point 80 ° C., solid content 40% by mass) 22.63 parts by mass Disaccharide trehalose (trade name Treha, Hayashibara Shoji, melting point 97 ° C.) 20% by mass aqueous solution 2.00 parts by mass Sodium polyacrylate: Aqualic DL522
Aqueous solution (manufactured by Nippon Shokubai Co., Ltd.), solid content 10 mass% 25.00 mass parts Isopropyl alcohol 1.50 mass parts Pure water 48.88 mass parts Solid content concentration 10 mass%
The lithographic printing plate material was cut to a width of 660 mm and wound about 30 m around a paper core having an outer diameter of 76 mm to obtain a rolled lithographic printing plate material.

Example 2
The same pigment as in Example 1 except that the hydrophilic layer-containing pigment (Black # 3550) of Example 1 was changed to ETB-300 (manufactured by Titanium Industry Co., Ltd., average particle size: 0.2 μm).

Example 3
The same pigment as in Example 1 except that the hydrophilic layer-containing pigment (Black # 3550) in Example 1 was changed to RB-BL (manufactured by Titanium Industry Co., Ltd., average particle size: 1.1 μm).

Example 4
Except for the inorganic particles or particles coated with an inorganic material of Example 2 (Silton JC-20, Sylton AMT-08L) (Kamishima Chemical Industries, Calsees X-25, average particle size: 0.25 μm) Was the same as in Example 2.

Example 5
Example except that inorganic particles or particles coated with an inorganic material (Silton JC-20, SILTON AMT-08L) of Example 2 were changed to (manufactured by Sakai Chemical Industry Co., Ltd., LPZINK-11, average particle size: 11 μm). Same as 2.

Example 6
The configuration of Example 2 was the same as Example 2 except that the wax (A-118) of the image forming layer was changed to (Nippon Seiki Co., Ltd., EMUSTAR-0443, melting point: 55 ° C.).

Example 7
The configuration of Example 2 was the same as Example 2 except that the wax (A-118) of the image forming layer was changed to (Chikyo Oil & Fats Co., Ltd., High Micron ZJ-557, melting point: 120 ° C.).

Example 8
The configuration of Example 2 was the same as Example 2, except that the wax (A-118) of the image forming layer was 16.25 parts by mass and trehalose (Treha) was 27.5 parts by mass.

Example 9
In the configuration of Example 2, 24.25 parts by mass of wax (A-118) of the image forming layer, 6.67 parts by mass of sodium polyacrylate (DL522), and 1.00 parts by mass of trehalose (Treha) were used. Except for this, it was the same as Example 2.

(Image formation)
The printing plate material was wound around the exposure drum and fixed. For exposure, a laser beam having a wavelength of 830 nm and a spot diameter of about 20 μm is used. The exposure energy is 250 mJ / cm ² , and 2400 dpi (dpi means the number of dots per 2.54 cm) and 175 lines are formed. did. The exposed image is a halftone dot image of the entire printing plate material.

(Printing method)
Printing was performed under the following conditions. The printing plate material was attached to the plate cylinder as it was after exposure, and printed using the same printing sequence as the PS plate.

Printing machine: DAIYA F-1 manufactured by Mitsubishi Heavy Industries, Ltd.
Printing paper: OK top coat +
Printing speed: 6,000 sheets / hour Dampening solution: Astro Mark 3 (manufactured by Nikken Chemical Laboratory) 2% by mass
Ink: (TK High Unity Red by Toyo Ink Co.)
(Each evaluation method)
Foreign matter resistance The entire surface of the printing plate thus prepared is exposed with 50% halftone dots by the image forming method described above. Next, printing is started under the conditions of the printing method described above, and is temporarily stopped when about 50 sheets are printed. With the ink on the blanket of the printing press, a nylon fishing line (148 μm) cut to about 5 mm is pasted on the blanket as a substitute for dust and foreign matter. After that, printing is started, and every time 100 sheets are printed, the fishing line is wiped off little by little to print up to 1000 sheets. Thereafter, the blanket is washed and printing is performed again, and the 100th sheet is sampled to evaluate the degree of damage to the printed matter. The thing which did not show the scar of a fishing line to the 500th sheet was set as the pass.

Printing durability The number of printed sheets at the time when the 50% halftone image started to fade was used as an index of printing durability. Those having a printing durability of 10,000 sheets or more were regarded as acceptable.

Non-image area stain The density of the portion of the printed material not exposed to the laser (non-image area) was measured, and the value measured in the M mode using Macbeth RD918 was less than 0.10. .

  From Table 1 and Table 2, the printing plate material and the printing method of the present invention have good impact from foreign matter, printing durability, and stain on the non-image area of the printed material in handling before development of the printing plate. It can be seen that the workability is equivalent.

Claims (3)

The average particle size of the pigment contained in the hydrophilic layer is 0.1 μm to 1.0 μm, and the average particle size of the inorganic particles other than the pigment or particles coated with an inorganic material is 0.5 μm to 10 μm. Planographic printing plate material. The melting point of the hot-melt particles contained in the image forming layer is 60 ° C to 100 ° C, and the content in the solid content in the image forming layer is 70% by mass to 95% by mass. The lithographic printing plate material described. A printing method comprising printing using the printing plate material according to claim 1 or 2 having on-press developability.