JP2005169902A - Forming method and developing method of image of printing plate material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method and a developing method of an image of a printing plate material which are excellent in plate wear resistance and cause little stain of a non-image part. <P>SOLUTION: The printing plate material having on-machine developability has an image forming layer of a thermosetting resin or a polymerizable monomer in the main on a grained aluminum base. In the forming method of the image of the printing plate material, the material is exposed to a laser beam of a wavelength of 700-1,100 nm, while masking the outside of a portion thereof wherein the beam intensity is above 1/16 to 1/2 of that of the central part of the beam. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method and a developing method for a printing plate material, and more particularly to an image forming method and a developing method for a printing plate material capable of forming an image by a computer-to-plate (CTP) method.

  Along 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 development process using a special chemical agent is unnecessary, and it can be applied to a printing machine having a direct imaging (DI) function, and is a general-purpose type thermal processless plate having the same usability as a PS plate. Expectations are growing.

  Generally, a thermal laser recording system having a wavelength of near infrared to infrared is mainly used for image formation of a thermal processless plate. Thermal processless plates capable of image formation by this method are roughly classified into an ablation type, a thermal fusion type, a phase change type, and a polymerization / crosslinking type, which will be described later.

  Examples of the ablation type are described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, and JP-A-10-244773. The thing that is. In these, for example, a hydrophilic layer and a lipophilic layer are laminated on a base material with either layer as a surface layer. If the surface layer is a hydrophilic layer, it is possible to form an image portion by exposing it like an image, ablating the hydrophilic layer and removing it like an image to expose the lipophilic layer.

  Examples of the heat fusion type include those using thermoplastic fine particles and a water-soluble binder in the image forming layer on a hydrophilic layer or an aluminum grain as disclosed in Japanese Patent No. 2938397. . The Thermo Lite manufactured by Agfa is a processless plate of this type. If this method is used, it is sufficient if there is energy to be fused, and less energy is required for image formation compared to the ablation type and phase change type, and high-speed lasers can increase the speed. .

  As a phase change type, a hydrophobized precursor particle is contained in a hydrophilic layer that is not removed during printing, as described in JP-A-11-240270, and the exposed area is changed from hydrophilic to lipophilic. It is possible to change the phase.

  Polymerization / crosslinking types include methods as described in US Pat. No. 6,548,222. With this method, the grain of the aluminum base material can be used, and the image forming layer can be strengthened by three-dimensional crosslinking, and further, since the image layer is strong, the anchoring effect between the aluminum equipment and the image forming layer can be achieved. Adhesion also becomes strong and printing durability can be greatly improved.

These CTPs use infrared lasers to form images, but conventionally used laser light has an average intensity (light quantity) like ordinary sunlight or light from electric lamps. It is not something with. Generally, it is a beam light and has a characteristic that the intensity increases as it becomes the center. The intensity distribution is represented by a Gaussian function, and the beam diameter (2ω0) generally indicates 1 / e ² of the maximum intensity Imax at the center of the beam. Therefore, as the distance from the center of the laser beam increases, the intensity (light quantity) decreases rapidly.

  The printed matter is composed of small dots called halftone dots, and the printed matter is obtained by forming this halftone image on the printing plate material. The gradation is expressed by changing the size of the halftone dots. Yes.

  Conventionally, the gradation (brightness) is expressed by changing the size (area) of the halftone dot itself, which is called the AM screening method. Instead of this, a method called an FM screening method in which dots of the same size are randomly arranged and the density is represented by the density of dots has been used in recent years. Since this method expresses light and shade within a certain area, it has the advantage of being able to reproduce close to continuous tone, and to handle multi-color printing of four or more colors. However, since the FM screening method is composed of fine dots, the dot sharpness is required as compared with the AM screening method. Conventionally used infrared laser light has low light intensity around the laser spot, so photothermal conversion is likely to be non-uniform, and the size of the formed halftone dots tends to fluctuate, resulting in a uniform and accurate halftone image. There was a limit to making it.

Further, in a printing plate material having on-press developability, the image forming layer is fused, cured, phase-changed, or removed by a single exposure (see, for example, Patent Documents 1 and 2), but there is no development process. For this reason, the uniformity of the laser beam is directly reflected in the accuracy of the image, so it is difficult to form a fine image with the conventional laser beam and the laser beam is weak. The printing durability was poor, and the non-image area was stained.
Japanese Patent Laid-Open No. 9-211182 (page 5 0035) JP-A-11-237743 (Example 1)

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method and a developing method for a printing plate material which has excellent printing durability and little non-image area contamination.

The above object of the present invention has been achieved by the following constitution.
(Claim 1)
An on-press developable printing plate material having an image forming layer mainly composed of a thermosetting resin or a polymerizable monomer on a grained aluminum base material. Beam intensity at the center of a laser beam having a wavelength of 700 nm to 1100 nm. A method for forming an image of a printing plate material, wherein the exposure is carried out while masking the outside from a portion that is larger than 1/16 and smaller than 1/2.
(Claim 2)
2. The printing plate material image forming method according to claim 1, wherein the printing plate material comprises laminating a hydrophilic layer containing a photothermal conversion material between an aluminum substrate and the image forming layer.
(Claim 3)
An on-press developable printing plate material having an image forming layer mainly composed of a thermosetting resin or a polymerizable monomer on a grained aluminum base material. Beam intensity at the center of a laser beam having a wavelength of 700 nm to 1100 nm. A method for developing a printing plate material, comprising exposing a mask from outside at a portion greater than 1/16 and less than or equal to 1/2, attaching the image to a printing machine as it is after exposure, and starting a printing operation.
(Claim 4)
The method for developing a printing plate material according to claim 3, wherein the printing plate material comprises a hydrophilic layer containing a photothermal conversion material laminated between an aluminum substrate and an image forming layer.

  According to the present invention, it is possible to provide an image forming method and a developing method for a printing plate material which is excellent in printing durability and has little non-image area contamination.

  Hereinafter, embodiments of the present invention will be described.

  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 a grained aluminum substrate. 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 due to 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.

(Base material)
As a base material, 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.

The aluminum substrate may be subjected only to anodizing treatment, but surface treatment conventionally used may be performed. For example, boehmite processing or pore wide processing alone processing and combination processing as shown below can be mentioned. As the conditions for the boehmite treatment, the aluminum plate may be anodized and then treated with hot water or steam, but preferably ammonium acetate, sodium silicate, sodium nitrite, dichromate, etc. It is preferable to immerse in an aqueous solution. The temperature during the treatment is 70 to 100 ° C., preferably 75 to 90 ° C., and the treatment time is 5 to 120 seconds, preferably 10 to 90 seconds. The pH of the aqueous solution is 7 to 11, preferably 7.5 to 10.5. If the temperature and time are insufficient or the pH is low, the surface treatment of the aluminum plate is not performed sufficiently. Conversely, if the temperature and time are too high or the pH is too high, the aluminum dissolves and roughens. The effect of performing is lost. Within these conditions, a boehmite (Al ₂ O ₃ (H ₂ O)) structure is formed on the aluminum surface.

  As conditions for the pore wide treatment, when an acid treatment is performed, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid or phosphoric acid or a mixture thereof, and the concentration is preferably 10 to 500 g / L, and preferably 20 to 100 g / L. Is more preferable. As temperature, 20-90 degreeC is preferable and 30-80 degreeC is more preferable. The immersion time is preferably 10 to 300 seconds, more preferably 30 to 120 seconds. Moreover, when processing with aqueous alkali solution, it is preferable to use at least 1 sort (s) of aqueous solution chosen from sodium hydroxide, potassium hydroxide, and lithium hydroxide, and 11-13 are preferable as pH of aqueous solution, 11 .5 to 12.5 is more preferable. As temperature, 20 to 90 degreeC is preferable and 30 to 80 degreeC is more preferable. The immersion time is preferably 10 to 300 seconds, more preferably 30 to 120 seconds.

  In the present invention, after each treatment, an immersion treatment may be further performed with a hydrophilic compound. Suitable hydrophilic compounds include citric acid, carboxymethylcellulose, chitosan, pullulan, alginic acid, oxalic acid, phthalic acid, formic acid, phytic acid, ammonium hexafluorophosphate, glycine, polyvinylphosphonic acid, other saccharide compounds, and These sodium salts can be mentioned. The pH is preferably 7 to 11, the temperature is preferably 60 to 100 ° C., and the treatment time is preferably 5 to 120 seconds.

  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)
In the present invention, a hydrophilic layer may be provided between the aluminum substrate and the image forming layer. The hydrophilic layer may be a single layer or may be formed from a plurality of layers. By applying this hydrophilic layer, it is possible to convert laser light into heat more efficiently than before, firmly bonding the interface between the hydrophilic layer and the image forming layer, and the image forming layer itself. It can be cured sufficiently. Preferably 0.1 to 10 g / m ² as the amount with the hydrophilic layer, 0.2-5 g / m ² is more preferable.

  As the hydrophilic material used for the hydrophilic layer, a metal oxide is 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. Further, the surface of the particles may be subjected to surface treatment. 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 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.

  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) ) ".

  The hydrophilic layer of the printing plate material of 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 described later can be preferably used.

(Porous silica or porous aluminosilicate particles)
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. It is possible to control the porosity and particle size of these composite particles by adjusting the production conditions. The porosity of the particles should be 1.0 ml / g or more in pore volume before dispersion. Preferably, it is 1.2 ml / g or more, more preferably 1.8 to 2.5 ml / g or less.

  The pore volume is closely related to the water retention of the coating film, and the larger the pore volume, the better the water retention, the less smudged during printing, and the greater the water volume latitude, but greater than 2.5 ml / g. Since the particles themselves become very brittle, the durability of the coating film decreases. When the pore volume is less than 1.0 ml / g, it is difficult to stain during printing and the water amount latitude is insufficient. 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 (for example, when it is crushed during dispersion). . If unnecessarily coarse particles are present, porous and steep protrusions are formed on the surface of the hydrophilic layer, and ink tends to remain around the protrusions, which may deteriorate non-image area stains and blanket stains.

(Zeolite particles)
Zeolite is a crystalline aluminosilicate and is a porous body having regular three-dimensional network voids having a pore diameter of 0.3 to 1 nm. The general formula combining natural and synthetic zeolite is expressed as follows:

(M ₁ , M ₂ 1/2) _m (Al _m Si _n O _{2 (m + n)} ) · xH ₂ O
Here, M ₁ and M ₂ are exchangeable cations, and M ₁ is Li ⁺ , Na ⁺ , K ⁺ , Tl ⁺ , Me ₄ N ⁺ (TMA), Et ₄ N ⁺ (TEA), Pr _4. N ⁺ (TPA), C ₇ H ₁₅ N ₂ ⁺ , C ₈ H ₁₆ N ^+, etc., and M ₂ is Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ , C ₈ H ₁₈ N ₂ ^{2. +} Etc. Further, n ≧ m, and the value of m / n, that is, the Al / Si ratio is 1 or less. The higher the Al / Si ratio, the greater the amount of exchangeable cations, and thus the higher the polarity and therefore the higher the hydrophilicity. A preferable Al / Si ratio is 0.4 to 1.0, and more preferably 0.8 to 1.0. x represents an integer.

The zeolite particles used in the present invention are preferably synthetic zeolites having a stable Al / Si ratio and a relatively sharp particle size distribution. For example, zeolite A: Na ₁₂ (Al ₁₂ Si ₁₂ O ₄₈ ) 27H ₂ O; Al / Si ratio 1.0, zeolite X: Na ₈₆ (Al ₈₆ Si ₁₀₆ O ₃₈₄ ) • 264H ₂ O; Al / Si ratio 0.811, zeolite Y: Na ₅₆ (Al ₅₆ Si ₁₃₆ O ₃₈₄ ) · 250H ₂ O; Al / Si ratio 0.412 and the like.

  By containing highly hydrophilic porous particles having an Al / Si ratio of 0.4 to 1.0, the hydrophilicity of the hydrophilic layer itself is greatly improved, it is difficult to get dirty during printing, and the water latitude is widened. In addition, the dirt on the fingerprint marks is greatly improved. When the Al / Si ratio is less than 0.4, the hydrophilicity is insufficient, and the effect of improving the performance becomes small.

  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. 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.

  The size of the flat lamellar mineral particles is 20 μm or less in average particle diameter (maximum particle length) in the state of being contained in the layer (including the case where the swelling process and dispersion peeling process have been performed). The average aspect ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, the average particle size is 5 μm or less, and the average aspect ratio is more preferably 50 or more. More preferably, the particle size 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. If the particle diameter is out of the above range, the effect of suppressing scratches due to scratching may be reduced. Further, when the aspect ratio is less than the above range, the flexibility becomes insufficient, and the effect of suppressing scratches due to scratching may also be 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. 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 layer 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 / Agne Jofusha) or is described in this document. Known methods described in the cited documents 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 polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone.

  Further, it may contain a cationic resin, and as the cationic resin, 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.

  In a more preferred embodiment of the present invention, the hydrophilic organic resin contained in the hydrophilic layer is water-soluble, and at least a part of the hydrophilic organic resin remains in a water-soluble state and exists in a state that can be eluted in water. Is mentioned. Even if it is a water-soluble material, when it is cross-linked by a cross-linking agent or the like and becomes insoluble in water, there is a concern that its hydrophilicity is lowered and print performance is deteriorated.

  As the water-soluble material contained in the hydrophilic layer of the present invention, saccharides are preferable. By including saccharides in the hydrophilic layer, an effect of improving the resolution of image formation or improving printing durability can be obtained in combination with a functional layer having an image forming ability described later. 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 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 applying and drying the hydrophilic 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.

  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.

  Moreover, the hydrophilic layer (coating solution) 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 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 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.

(Photothermal conversion material)
Examples of photothermal conversion materials include the following materials. 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-280750, JP-A-1-293342, JP-A-2-2074, JP-A-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-3-97589, and JP-A-3-103476 And the like. These can be used alone or in combination of two or more. Moreover, it describes in each gazette of Unexamined-Japanese-Patent No. 11-240270, 11-26562, Unexamined-Japanese-Patent No. 2000-309174, 2002-49147, 2001-162965, 2002-144750, 2001-219667. These compounds can also be preferably used.

  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 has conductivity or is a semiconductor can be used. Examples of the former include black iron oxide and black composite metal oxides containing two or more metals. Examples of the latter include Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , TiO ₂ reduced TiO (titanium oxynitride, generally titanium black), etc. Is mentioned. Further, it can also be used 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.

  Among these photothermal conversion materials, black iron oxide and black composite metal oxides containing two or more metals are more preferable materials.

The black iron oxide (Fe ₃ O ₄ ) is preferably particles having an average particle diameter of 0.01 to 1 μm and an acicular ratio (major axis diameter / minor axis diameter) of 1 to 1.5. It is preferably substantially spherical (acicular ratio 1) or has an octahedral shape (acicular ratio about 1.4).

Examples of such black iron oxide particles include TAROX series manufactured by Titanium Industry Co., Ltd. As the spherical particles, BL-100 (particle diameter 0.2 to 0.6 μm), BL-500 (particle diameter 0.3 to 1.0 μm), or the like can be preferably used. Further, as octahedral shaped particles, ABL-203 (particle size 0.4 to 0.5 μm), ABL-204 (particle size 0.3 to 0.4 μm), ABL-205 (particle size 0.2 to 0) .3 μm), ABL-207 (particle size: 0.2 μm) and the like can be preferably used. Furthermore, particles whose surface is coated with an inorganic material such as SiO ² can also be preferably used. As such particles, spherical particles coated with SiO ₂ : BL-200 (particle size 0.2-0) .3 μm), octahedral shaped particles: ABL-207A (particle size 0.2 μm).

  Specifically, the black composite metal oxide 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 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, they 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.

  Among these, in the present invention, it is preferable to use a dye, and it is more preferable to use a dye that is less colored with visible light.

(Image forming layer)
The image forming layer forms an image by heat generated by exposure with an infrared laser. The image forming layer of the present invention is characterized by containing a material having polymerization or crosslinkability.

  As water-soluble or water-dispersible resins that can be used for polymerization or cross-linking, oil-modified alkyd resin, vinyl-modified alkyd resin, epoxy-modified alkyd resin, melamine resin, silicon / acrylic resin, epoxy-acrylic resin, acrylic Resin, phenol resin, epoxy resin, polyurethane resin, isocyanate compound, carbodiimide compound, oligosaccharide, polysaccharide, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, Methyl methacrylate-butadiene copolymer conjugated diene polymer latex, acrylic polymer latex, vinyl polymer latex, polyacrylate, polyacrylamide, polyvinyl chloride Pyrrolidone, and the like.

  Examples of organic solvent resins include monomethacrylate, monoacrylate, dimethacrylate, diacrylate, triacrylate, triester, tetraacrylate, hexaacrylate, urethane (meth) acrylate, epoxy acrylate, and oligomers thereof, styrene / acrylate Copolymers, acrylic ester copolymers, PVA / acrylic resins and the like can be mentioned. Among these, water-soluble and water-dispersed resins are particularly preferable.

  The present invention can also contain heat-meltable fine particles and heat-fusible fine particles. These are fine particles formed of a material generally classified as wax. 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, 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 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.

  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 fine particle in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is still more preferable.

  Examples of the heat-fusible fine particles according to the present invention include thermoplastic hydrophobic polymer fine particles, and there is no specific upper limit for the softening temperature of the polymer fine particles, but the temperature is the decomposition of the polymer fine particles. It is preferable that the temperature is lower than the temperature. 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 heat-fusible 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-fusible fine particles is applied onto the porous hydrophilic layer described later, the heat-fusible fine particles It becomes easy to get into the pores or into the gaps between the fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, resulting in fear of soiling. When the average particle size of the heat-fusible fine particles is larger than 10 μm, the resolution is lowered.

  Further, the composition of the heat fusible particles may be continuously changed 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 still more preferable.

  The image forming layer may contain the above-described photothermal conversion material. Further, the image forming layer can contain a water-soluble surfactant. 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). Furthermore, it may contain an acid (phosphoric acid, acetic acid, etc.) or an alkali (sodium hydroxide, silicate, phosphate, etc.) for pH adjustment.

The amount per image forming 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.

  As an aspect of the present invention, the image forming layer is adhered to the hydrophilic layer surface by exposure with a laser having a wavelength of 700 to 1100 nm.

(Protective layer)
A protective layer may be provided as an upper layer of the image forming layer. As a material used for the protective layer, the above-mentioned water-soluble resin and water-dispersible resin can be preferably used. In addition, hydrophilic overcoat layers described in JP-A Nos. 2002-019318 and 2002-086948 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 formation method: infrared laser)
The printing plate material of the present invention is characterized in that exposure is performed with a laser beam masking a portion having a low beam intensity. The wavelength of the infrared laser is from the near infrared to the infrared region, and is preferably 700 nm to 1100 nm. Examples of the infrared laser used include a solid laser and a semiconductor laser.

  The beam diameter of the infrared laser used before passing through the mask is preferably 10 to 80 μm, more preferably 10 to 40 μm, from the viewpoints of productivity and image quality. If the beam diameter is less than 10 μm, the area that can be exposed per unit time for the mask is reduced, so that the productivity may be remarkably reduced. Conversely, if it exceeds 80 μm, the obtained image quality may be deteriorated.

  The portion of the laser spot to be masked is on the outside from the portion where the intensity of the laser beam center is 1/2 to less than 1/16, and more preferably on the outside from the portion where the intensity is 1/2 to 1/8. As long as the mask can satisfy the above-described conditions, it may be placed in any part immediately before the laser oscillator or before or after the condenser lens. The beam diameter after passing through the mask is preferably 5 to 30 μm. Further, the shape of the mask is not limited, and there is no particular limitation on the shape of the circle, square, or rectangle.

  In addition, as a product, a CTP exposure machine (Trendsetter) manufactured by Creo Corporation having a rectangular laser spot shape can also be suitably used.

(On-press development method)
The image forming layer of the printing plate material of the crosslinking or polymerization method using an infrared laser, which is a preferred embodiment of the printing plate material of the present invention, has an infrared laser exposed portion becomes an oleophilic image portion by crosslinking or polymerization, and an unexposed portion is removed. It becomes a non-image part. The unexposed portion can be removed by washing with water, but 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 portion of the image forming layer on the printing press can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. The various sequences can be performed. In such a 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.

  (1) As a sequence for starting printing, the printing drum is brought into contact with the watering roller for one to several dozen rotations, then the ink roller is brought into contact with the printing drum for one to several dozen rotations, and then printing is performed. To start.

  (2) As a sequence for starting printing, contact the ink roller to rotate the plate cylinder from 1 to several tens of rotations, then contact the watering roller to rotate the plate cylinder from 1 to several tens of rotations, and then perform printing. 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 1 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.

Example 1
(Base material)
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. Perform electrolytic graining treatment is divided into 12 times, and the quantity of electricity used in one treatment (at a positive polarity) as the 40C / dm ^2, treatment quantity of electricity 480C / dm ² in total (at a positive polarity). 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 kept 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 1% by mass sodium dihydrogen phosphate aqueous solution maintained at 70 ° C. for 30 seconds, washed with water, dried at 80 ° C. for 5 minutes, Got.

(Preparation of image forming layer)
(Image forming layer coating solution P-1)
Water-based polyurethane resin: Takelac W-615 (manufactured by Mitsui Takeda Chemical Co., Ltd.) solid content 35% by mass 17.1 parts by mass Water-based block isocyanate: Takenate XWB-72-N67 (manufactured by Mitsui Takeda Chemical Co., Ltd.) 45% by mass solid content 7.1 Mass parts Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10 mass% 5.0 mass parts Photothermal conversion dye: ethanol solution of ADS830AT (American Dye Source), 1 mass% 30. 0 parts by mass Pure water 40.8 parts by mass [Preparation of printing plate samples 1 to 5]
Printing plate samples were prepared with the configuration shown in Table 1. As the conditions at the time of production, the image forming layer was applied using a wire bar and dried, followed by aging treatment to obtain a printing plate sample.

Image forming layer: amount with drying 1.50 g / m ² , drying condition 55 ° C./3 minutes aging condition: 40 ° C./24 hours (image formation by infrared laser exposure)
The printing plate material was wound around the exposure drum and fixed. The exposure is a circular laser beam with a wavelength of 830 nm and a spot diameter of about 20 μm without a mask, and the outer portion from where the beam intensity is 1/16, 1/8, 1/4, and 1/2 of the center. 2400 dpi (dpi represents the number of dots per inch or 2.54 cm), 175 lines, using a square laser beam having a spot diameter of about 20 μm after passing through the mask and exposure energy of 250 mJ / cm ² To form an image. The exposed image includes a solid image and a 1 to 99% halftone dot image.

(Printing method)
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening water: 2% by mass of Astro Mark 3 (manufactured by Nikken Chemical Laboratory), ink (TK High Unity Red, manufactured by Toyo Ink Co., Ltd.) Used to print. 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.

[Evaluation]
(Print life)
The number of printed sheets at the time when the 3% halftone image started to be missing was used as an index of printing durability. Those having printing durability of 50,000 sheets or more were regarded as acceptable.

(Non-painted area dirt)
The density | concentration of the part (non-image part) which was not exposed with the laser of a printed matter was measured, and the value measured in the mode of M using Macbeth RD918 was set as the pass.

  From Table 1, the printing plate material of the present invention has a clear print image, good on-press developability and printing durability, no stain on non-image areas, and excellent printability. I understand that.

Example 2
The same aluminum plate as in Example 1 was used.

(Preparation of hydrophilic layer)
A material having the following composition was sufficiently stirred and mixed using a homogenizer and then filtered to prepare a hydrophilic layer coating solution having a solid content of 15% by mass. The hydrophilic layer coating solution was applied onto the substrate 1 using a wire bar so that the amount applied after drying was 2.0 g / m ² and dried at 100 ° C. for 3 minutes. Next, an aging treatment at 60 ° C. for 24 hours was performed.

(Hydrophilic layer coating solution)
Black iron oxide particles: ABL-207 (manufactured by Titanium Industry Co., Ltd., octahedral shape, average particle size: 0.2 μm, specific surface area: 6.7 m ^{2 /} g, Hc: 9.95 kA / m, σs: 85.7 Am ² / Kg, σr / σs: 0.112) 12.50 parts by mass Colloidal silica (alkaline) Snowtex-XS (manufactured by Nissan Chemical Co., Ltd., solid content 20% by mass) 60.62 parts by mass Trisodium phosphate / 12 water 10% by mass aqueous solution (reagent manufactured by Kanto Chemical Co., Inc.)
1.13 parts by mass Water-soluble chitosan: 10% by mass aqueous solution of Flownack S (manufactured by Kyowa Technos)
2.50 parts by mass Surfactant: 1% by mass aqueous solution of Surfynol 465 (produced by Air Products)
1.25 parts by mass Pure water 22.00 parts by mass (Image-forming layer coating solution P-2)
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) 16.5 parts by weight disaccharide trehalose (trade name Treha, Hayashibara Shoji, melting point 97 ° C.) Aqueous solution, solid content 10 mass% 5.0 mass parts Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10 mass% 5.0 mass parts Colloidal silica: Snowtex PS-M (Nissan Chemical) Manufactured by Kogyo Co., Ltd.), solid content 20% by mass
10.0 parts by mass Photothermal conversion dye: ethanol solution of ADS830AT (manufactured by American Dye Source), 1% by mass 30.0 parts by mass Pure water 33.5 parts by mass (Image-forming layer coating solution P-3)
Tetraacrylate compound: MEK solution of NK ester AD-TMP (manufactured by Shin-Nakamura Chemical Co., Ltd.), concentration 40% by mass 15.0 parts by mass Polyvinylpyrrolidone: PVP-18 (manufactured by Daido Kasei) solid content 20% by mass
16.0 parts by mass Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by mass 5.0 parts by mass Photothermal conversion dye: ethanol solution of ADS830AT (American Dye Source), 1 mass % 30.0 parts by mass MEK 34.0 parts by mass (Image-forming layer coating solution P-4)
Carnauba wax emulsion: A118 (Gifu Shellac Co., Ltd., average particle size 0.4 μm, melting point 80 ° C., solid content 40% by mass) 4.3 parts by mass Aqueous polyurethane resin: Takelac W-615 (Mitsui Takeda Chemical Co., Ltd.) solid content 35% by mass 14.3 parts by mass Aqueous blocked isocyanate: Takenate XWB-72-N67 (manufactured by Mitsui Takeda Chemical Co., Ltd.) Solid content 45% by mass 5.6 parts by mass Sodium polyacrylate: Aqualic DL522 (manufactured by Nippon Shokubai Co., Ltd.) Aqueous solution, solid content 10% by weight 5.0 parts by weight Photothermal conversion dye: ethanol solution of ADS830AT (manufactured by American Dye Source), 1% by weight 30.0 parts by weight Pure water 40.8 parts by weight (image forming layer coating solution P -5)
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) 4.3 parts by mass tetraacrylate compound: NK ester AD-TMP (manufactured by Shin-Nakamura Chemical Co., Ltd.) MEK solution, concentration 40% by mass 12.5 parts by mass Polyvinylpyrrolidone: PVP-18 (manufactured by Daido Kasei) solid content 20% by mass
12.5 parts by mass Sodium polyacrylate: Aquaric DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10 mass% 5.0 parts by mass Photothermal conversion dye: ethanol solution of ADS830AT (American Dye Source), 1 mass % 30.0 parts by mass MEK 35.7 parts by mass [Preparation of printing plate materials 11 to 20]
Printing plate materials 11 to 20 having the configurations shown in Table 2 were produced. As conditions for the production, each layer was applied using a wire bar and dried, and then an aging treatment was performed to obtain a printing plate material.

Image forming layer: amount with drying 1.50 g / m ² , drying condition 55 ° C./3 minutes aging condition: 40 ° C./24 hours (image formation by infrared laser exposure)
The printing plate material was wound around the exposure drum and fixed. For exposure, a square laser beam having a wavelength of about 830 nm and a beam intensity of 1/8 of the central portion is masked and the spot diameter after passing through the mask is about 20 μm. The exposure energy is 250 mJ / cm ^2. Images were formed at 2400 dpi and 175 lines. The exposed image includes a solid image and a 1 to 99% halftone dot image.

(Printing method)
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening water: 2% by mass of Astro Mark 3 (manufactured by Nikken Chemical Laboratory), ink (TK High Unity Red, manufactured by Toyo Ink Co., Ltd.) Used to print. 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.

[Evaluation]
(Print life)
The number of printed sheets at the time when the 3% halftone image started to be missing was used as an index of printing durability. Those having a printing durability of 100,000 sheets or more were regarded as acceptable.

  From Table 2, the printing plate materials 16 and 18 to 20 having a hydrophilic layer have clear print images, good on-press developability and printing durability, and excellent printability. I understand that. Although the printing plate material 17 has a hydrophilic layer, the image forming layer (P-2) does not have a thermosetting resin or a polymerizable monomer. The printability is not good.

Claims (4)

An on-press developable printing plate material having an image forming layer mainly composed of a thermosetting resin or a polymerizable monomer on a grained aluminum base material. Beam intensity at the center of a laser beam having a wavelength of 700 nm to 1100 nm. A method for forming an image of a printing plate material, wherein the exposure is carried out while masking the outside from a portion that is larger than 1/16 and smaller than 1/2. 2. The printing plate material image forming method according to claim 1, wherein the printing plate material comprises laminating a hydrophilic layer containing a photothermal conversion material between an aluminum substrate and the image forming layer. An on-press developable printing plate material having an image forming layer mainly composed of a thermosetting resin or a polymerizable monomer on a grained aluminum base material. Beam intensity at the center of a laser beam having a wavelength of 700 nm to 1100 nm. A method for developing a printing plate material, comprising exposing a mask from outside at a portion greater than 1/16 and less than or equal to 1/2, attaching the image to a printing machine as it is after exposure, and starting a printing operation. The method for developing a printing plate material according to claim 3, wherein the printing plate material comprises a hydrophilic layer containing a photothermal conversion material laminated between an aluminum substrate and an image forming layer.