JP2007190796A - Lithographic printing plate material and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate material of aboard-the-machine development type using a plastic support with excellent resistance to plate wear. <P>SOLUTION: This lithographic printing plate material has an undercoat layer, a hydrophilic layer and an imaging layer, formed in that order, on the plastic support, and can perform a final imaging process by developing an image aboard the printing machine. In addition, the hydrophilic layer has a water-soluble resin with a silanol group introduced into the side chain. Also the imaging method is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate material and an image forming method. More specifically, the present invention relates to a lithographic printing plate material and an image forming method in which water resistance of a hydrophilic layer, coating film strength and hydrophilicity are compatible.

  Along with the digitization of print data, there is a need for a CTP that is inexpensive, easy to handle, and has the same printability as the PS plate. In particular, in recent years, there is an increasing expectation for a so-called processless plate that does not require a development process using a special agent and can be applied to a printing press having a direct imaging (DI) function.

  The processless plate is mainly a so-called thermal type that forms an image by infrared laser exposure, but the thermal type can be roughly divided into two types.

  One type of thermal type printing plate material is an ablation type, for example, by laminating two layers having different affinity for dampening water or ink used for printing on a substrate, The surface-side layer is ablated by laser exposure and completely removed. However, this type of printing plate material has a problem in that it is necessary to attach to the exposure apparatus a mechanism for completely sucking and removing the scattered matter on the ablated surface side layer, and the apparatus cost is greatly increased. In addition, since the energy required for exposure is relatively high, it is necessary to reduce the beam linear velocity during exposure (for example, to reduce the rotation speed of the exposure drum), which may reduce image formation productivity.

  Another type of thermal type printing plate material is an on-press development type. In this type, for example, two layers having different affinity for dampening water or ink used for printing are formed on a substrate, and the adhesive force between the surface side layer and the layer below is formed by laser exposure. It is made to change and a part with weak adhesive force is removed on a printing machine.

  As the structure of the processless plate, it is possible to use the same aluminum grain as the PS plate, but from the viewpoints of freedom of layer structure and cost reduction, various types of processes using coated and formed hydrophilic layers. A wrest plate has been proposed (see, for example, Patent Document 1).

However, unlike the PS plate, the hydrophilic layer formed by coating is greatly limited in the types of resin that can be added as a binder in order to achieve surface hydrophilicity, and measures both water resistance, mechanical strength and surface hydrophilicity. It is difficult.
Japanese Patent Laid-Open No. 2001-138852

  An object of the present invention is to provide an on-press development type lithographic printing plate material and an image forming method using a plastic support having excellent printing durability.

  The above object of the present invention can be achieved by the following configuration.

  1. A lithographic printing plate material in which a subbing layer, a hydrophilic layer, and an image forming layer are sequentially provided on a plastic support, and are developed on a printing press to form a final image. A lithographic printing plate material, wherein a water-soluble resin having a silanol group in the chain is introduced.

  2. 2. The lithographic printing plate material as described in 1 above, wherein the coating solution for the hydrophilic layer has a pH of 9 or more and less than 12.

  3. 3. The lithographic printing plate material according to 1 or 2, wherein at least one of a hydrophilic layer and an image forming layer provided in the lithographic printing plate material contains a photothermal conversion agent that converts near infrared rays into heat. .

  4). The lithographic printing plate material as described in any one of 1 to 3 above, wherein the hydrophilic layer is formed by a coating step and has a two-layer structure.

  5. 5. An image forming method comprising forming an image of the lithographic printing plate material according to any one of 1 to 4 by using a thermal head or a thermal laser.

  According to the present invention, an on-press development type lithographic printing plate material and an image forming method using a plastic support having excellent printing durability can be provided.

  The present invention will be described in more detail.

(Hydrophilic layer)
The hydrophilic layer of the present invention contains a water-soluble resin having a silanol group. Specific examples of the water-soluble resin having a silanol group of the present invention include, as a main skeleton, natural polymers such as gelatin, gum arabic, water-soluble soybean polysaccharides, and fiber derivatives (for example, carboxymethyl cellulose, carboxyethyl cellulose, Synthetic polymers such as methyl cellulose, white dextrin, pullulan, curdlan, chitosan, alginic acid, enzymatically decomposed etherified dextrin, polyvinyl alcohol (preferably having a saponification degree of 70 mol% or more), polyacrylic acid, its alkali Metal salt or amine salt, polyacrylic acid copolymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, Maleic acid / acrylic acid co-polymer And its alkali metal salt or amine salt, polyacrylamide, copolymer thereof, polyhydroxyethyl acrylate, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamide-2-methyl-1- Examples include propanesulfonic acid, alkali metal salts or amine salts thereof, poly-2-acrylamido-2-methyl-1-propanesulfonic acid copolymer, alkali metal salts or amine salts thereof, and the like. Into which a silanol group is introduced.

  Among these, those having acrylic acid and polyvinyl alcohol as the main skeleton are preferable, and those having polyvinyl alcohol as the main skeleton are particularly preferable. Moreover, these can also be used in mixture of 2 or more types according to the objective. However, the present invention is not limited to these examples.

  In the present invention, the silanol group content of the water-soluble resin is preferably 0.01 mol% or more and less than 20 mol%, more preferably 0.05 mol% or more and less than 10 mol%. When it is less than 0.01 mol%, the coating strength of the hydrophilic layer is insufficient, and when it is 20 mol% or more, the hydroxyl groups of the water-soluble resin are reduced, and the hydrophilicity of the plate surface is lowered.

In the present invention, the coating amount of the water-soluble resin having a silanol group is preferably 0.001 g / m ² or more and less than 3.0 g / m ² . More preferably, they are 0.005 g / m < ² > or more and less than 2.0 g / m < ² >, More preferably, they are 0.01 g / m < ² > or more and less than 1.5 g / m < ² >. When the amount of the water-soluble resin having a silanol group deviates from the scope of the present invention, the hydrophilic layer is not sufficiently adhered, and the printing durability as a printing plate is lowered.

  Other materials for forming the hydrophilic layer are as follows.

  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 be in the form of a sphere, feather, or 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 having an average particle diameter of 20 nm or less to necklace-like colloidal silica is preferably 95: 5 to 5:95, more preferably 70:30 to 20:80, and still more preferably 60:40 to 30:70.

  As the porous material of the hydrophilic layer matrix of the present invention, porous metal oxide particles having a particle size of less than 1 μm can be contained. As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles described later can be preferably used.

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

  These particles can be controlled in porosity and particle size by adjusting the production conditions. The porous silica particles are particularly preferably those obtained from a wet gel.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, it is an amorphous composite particle 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, particles produced by adding other metal alkoxides at the time of production as composite particles having three or more components can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 0.5 ml / g or more in terms of pore volume, more preferably 0.8 ml / g or more, and further preferably 1.0 to 2.5 ml / g or less. preferable.

  The pore volume is closely related to the water retention of the coating film. The larger the pore volume, the better the water retention and the less smudged during printing, and the greater the water volume latitude, but greater than 2.5 ml / g. Then, since the particles themselves become very brittle, the durability of the coating film decreases. When the pore volume is less than 0.5 ml / g, the printing performance may be slightly insufficient.

Zeolite can also be used as the porous material of the present invention.
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 ) _0.5 ) _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 ^{+ and the} like, 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 zeolite 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. Also, fingerprint marks are 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.

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

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

  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.

  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 matrix. However, the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble solution are added to the hydrophilic layer coating solution. It is preferable that a structure having better printability can be obtained by forming a phase separation when the hydrophilic polysaccharide is applied and dried.

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

  The 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. Moreover, the photothermal conversion raw material mentioned later can also be contained. As the photothermal conversion material, in the case of a particulate material, the particle size is preferably less than 1 μm.

  In this invention, it is preferable to contain the particle | grains coat | covered with the inorganic particle or particle | grains whose particle size is 1 micrometer or more.

Porous, non-porous, organic resin particles, and inorganic fine particles may be used. 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, silica, triboli, diatomaceous earth, dolomite, etc., organic fillers include polyethylene fine particles, fluororesin particles, guanamine resin particles, acrylic resin particles, silicon resin particles, melamine resin particles, etc. I can list them. Examples of the inorganic coating filler include particles in which a core agent of organic particles such as PMMA, polystyrene, and melamine is coated with inorganic particles that are smaller in relay than the core agent particles. 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.

  Moreover, the particle | grains which carried out the metal plating of the core material of an organic particle can also be used. Examples of such particles include “Micropearl AU” manufactured by Sekisui Chemical Co., Ltd., in which resin particles are plated with gold.

  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. The particle size is preferably 1 to 12 μm, more preferably 1.5 to 8 μm, and further preferably 2 to 6 μm.

  When the particle diameter exceeds 12 μm, there is a concern that the resolution of image formation is reduced and the blanket stain is deteriorated.

  The amount of particles having a particle diameter of 1 μm or more is preferably 1 to 50% by mass, more preferably 5 to 40% by mass based on the entire hydrophilic layer.

  The hydrophilic layer as a whole preferably has a low content ratio of materials containing carbon such as organic resin and carbon black in order to improve hydrophilicity, and the total of these materials is preferably less than 9% by mass. More preferably, it is less than 5 mass%.

  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.

  The addition amount of the particles having a particle size of 1 μm or more is preferably 1 to 50% by mass, more preferably 5 to 40% by mass based on 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.

(Support)
Next, the support according to the present invention will be described. The constituent material of the plastic film support according to the present invention is preferably a plastic film, and examples thereof include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

Support according to the present invention is preferably from the viewpoint of imparting the handling aptitude to printing plate material of the present invention, the elastic modulus at 120 ° C. (E120) is ^{100kg / mm 2 ~600kg / mm 2} , more preferably from ^{120kg / mm 2 ~500kg / mm 2} . Specifically, polyethylene naphthalate (E120 = 410 kg / mm ² ), polyethylene terephthalate (E120 = 150 kg / mm ² ), polybutylene naphthalate (E120 = 160 kg / mm ² ), polycarbonate (E120 = 170 kg / mm ² ), Syndiotactic polystyrene (E120 = 220 kg / mm ² ), polyetherimide (E120 = 190 kg / mm ² ), polyarylate (E120 = 170 kg / mm ² ), polysulfone (E120 = 180 kg / mm ² ), polyethersulfone ( E120 = 170 kg / mm ² ) and the like. These may be used singly or may be laminated or mixed. Among them, particularly preferable plastic films include polyethylene naphthalate and polyethylene terephthalate.

  Here, the elastic modulus is obtained by using a tensile tester to obtain the slope of the stress with respect to the strain amount in a region where the strain indicated by the standard line of the sample conforming to JIS C2318 and the corresponding stress have a linear relationship. It is a thing. This is a value called Young's modulus, and in the present invention, the Young's modulus is defined as an elastic modulus.

  Furthermore, the support according to the present invention has an average film thickness from the viewpoint of improving handling suitability when the printing plate material is installed in a printing machine in order for the printing plate material of the present invention to exhibit the effects described in the present invention. Is in the range of 50 μm to 500 μm, and the thickness distribution is preferably 10% or less.

  The average film thickness of the support is preferably in the range of 110 μm to 500 μm as described above, more preferably in the range of 120 μm to 400 μm, and particularly preferably in the range of 125 μm to 300 μm.

  The thickness distribution of the support according to the present invention (a value obtained by dividing the difference between the maximum value and the minimum value by the average thickness and expressed as a percentage) is preferably 10% or less, more preferably 8 as described above. % Or less, particularly preferably 6% or less.

  Here, the method for measuring the thickness distribution of the support is as follows. The support cut out into a square having a side of 60 cm is drawn in a grid pattern at intervals of 10 cm vertically and horizontally, the thickness of these 36 points is measured, and the average value and maximum value are measured. Find the value and minimum value.

(Method for producing support)
In order to adjust the average film thickness and thickness distribution of the support according to the present invention to the above range, there is a method of adjusting the film forming conditions appropriately or adjusting with a smooth roller while reheating after film formation, In this invention, it is preferable to manufacture by the film forming process as described below.

  As a film forming means for the support, a thermoplastic resin is melted at a melting point (Tm) to Tm + 50 ° C., filtered through a sintered filter, and then extruded from a T-die to obtain a glass transition temperature (Tg) -50. An unstretched sheet is formed on a casting drum whose temperature is adjusted to from C to Tg. At this time, in order to make the thickness distribution within the above range, it is preferable to use an electrostatic application method or the like.

  The unstretched sheet is longitudinally stretched 2 to 4 times between Tg and Tg + 50 ° C. Further, as another method for adjusting the thickness distribution within the above range, it is preferable to perform multi-stage stretching in the longitudinal stretching. At this time, it is preferable to adjust the temperature of the post-stage stretching to be higher in the range of 1 ° C to 30 ° C than that of the pre-stage stretching, and it is more preferable to perform the stretching while adjusting the temperature to be higher in the range of 2 ° C to 15 ° C.

  The ratio of the former drawing is preferably 0.25 to 0.7 times the magnification of the latter drawing, and more preferably 0.3 to 0.5. After this, hold for 5 seconds to 60 seconds, more preferably 10 seconds to 40 seconds in the temperature range of Tg-30 ° C to Tg, and then laterally increase between 2.5 times and 5 times between Tg and Tg + 50 ° C. It is preferable to stretch.

  Thereafter, heat fixation is performed in a state of being gripped by the chuck at (Tm-50 ° C) to (Tm-5 ° C) for 5 seconds to 120 seconds. At this time, it is also preferable to reduce the chuck interval (thermal relaxation) by 0% to 10% in the width direction. After cooling this, a method such as obtaining a multiaxially stretched film after winding a knurling of 10 μm to 100 μm at the end (also referred to as providing a knurling height) is preferable.

(Fine particles)
Moreover, it is preferable to add 0.01 ppm-10 micrometers microparticles | fine-particles to said support body 1 ppm-1000 ppm for a handleability improvement.

  Here, the fine particles may be either organic or inorganic. Examples of inorganic substances include silica described in Swiss Patent No. 330,158 and the like, glass powder described in French Patent No. 1,296,995, and British Patent No. 1,173,181. Alkaline earth metals or carbonates such as cadmium and zinc described in the book can be used. Examples of organic substances include starch described in US Pat. No. 2,322,037 and the like, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and the like. No. 44-3643, etc., polyvinyl alcohol described in Swiss Patent No. 330,158 etc., polymethacrylate, US Pat. No. 3,079,257, etc., polyacrylonitrile, US Patent Organic fine particles such as polycarbonates described in US Pat. No. 3,022,169 can be used. The shape of the fine particles may be either regular or irregular.

(Underlayer)
In order to improve the coating property of the hydrophilic layer and the adhesion between the hydrophilic layer and the support according to the present invention, it is preferable to apply the undercoat layer to the plastic film.

  In the present invention, the undercoat layer preferably contains a water-soluble resin, and is selected from water-soluble natural polymers and synthetic polymers. Specific examples of water-soluble resins preferably used in the present invention include natural polymers such as gelatin, gum arabic, water-soluble soybean polysaccharides, fiber derivatives (for example, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), In the case of synthetic polymers such as modified products, white dextrin, pullulan, curdlan, chitosan, alginic acid, enzymatically decomposed etherified dextrin, polyvinyl alcohol (preferably having a saponification degree of 70 mol% or more), polyacrylic acid, its alkali metal Salt or amine salt, polyacrylic acid copolymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, malee Acid / acrylic acid copolymer And alkali metal salts or amine salts thereof, polyacrylamide, copolymers thereof, polyhydroxyethyl acrylate, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfone Examples thereof include acids, alkali metal salts or amine salts thereof, poly-2-acrylamido-2-methyl-1-propanesulfonic acid copolymers, alkali metal salts or amine salts thereof. Among these, gelatin and polo vinyl alcohol are preferable, and polyvinyl alcohol is particularly preferable. Moreover, these can also be used in mixture of 2 or more types according to the objective. However, the present invention is not limited to these examples.

In the present invention, the coating amount of the water-soluble resin is preferably 0.001 g / m ² or more and less than 3.0 g / m ² . More preferably, they are 0.005 g / m < ² > or more and less than 2.0 g / m < ² >, More preferably, they are 0.01 g / m < ² > or more and less than 1.5 g / m < ² >.

  In the present invention, it is preferable to contain an aqueous polyester modified with acrylic. The water-based polyester modified with acrylic is a dispersion polymer obtained by dispersing and polymerizing an acrylic resin in an aqueous solution in which water-based polyester is present. For example, the water-based polyester obtained by dissolving water-based polyester in hot water. It can be obtained by dispersing an acrylic resin in an aqueous solution and emulsion polymerization or suspension polymerization. The polymerization is preferably by emulsion polymerization.

  Examples of the polymerization initiator that can be used include ammonium persulfate, potassium persulfate, sodium persulfate, and benzoyl peroxide. Of these, ammonium persulfate is preferred. The polymerization can be carried out without using a surfactant, but a surfactant can also be used as an emulsifier for the purpose of improving the polymerization stability. In this case, both general nonionic and anionic surfactants can be used.

  Acrylic resins include acrylic monomers such as alkyl acrylate and alkyl methacrylate (the alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2- Ethyl hexyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.); hydroxy group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate; acrylamide, Methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymeth Amide group-containing monomers such as ruacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide; amino group-containing monomers such as N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate; glycidyl acrylate, glycidyl methacrylate, etc. Epoxy group-containing monomers; monomers containing carboxyl groups such as acrylic acid, methacrylic acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) or salts thereof. Examples of monomers other than acrylic monomers include epoxy group-containing monomers such as allyl glycidyl ether; sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) Or a monomer containing a salt thereof; a monomer containing a carboxyl group or a salt thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.); maleic anhydride, Monomers containing acid anhydrides such as itaconic anhydride; vinyl isocyanate; allyl isocyanate; styrene; vinyl trisalkoxysilane; alkyl maleic acid monoester; alkyl fumaric acid monoester; acrylonitrile; methacrylonitrile; Monoester; vinylidene chloride; vinyl acetate; vinyl chloride and the like. As the vinyl monomer, it is preferable to use an epoxy group-containing monomer such as glycidyl acrylate or glycidyl methacrylate from the viewpoint of coating strength.

  The amount of the acrylic resin used is preferably (aqueous polymer) / (acrylic resin) in a mass ratio of 99/1 to 5/95, more preferably 97/3 to 50/50. Preferably, it is in the range of 95 / 5-80 / 20.

  Moreover, the above-mentioned acrylic resin can be used for the acrylic resin contained in the undercoat layer of the present invention. It is environmentally preferable that the acrylic resin in the present invention is in the form of a polymer latex. The polymer latex refers to a polymer component in which a water-insoluble hydrophobic polymer is dispersed as fine particles in water or a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion polymerized, the micelle dispersed, or the polymer molecule has a partially hydrophilic structure and the molecular chain itself is molecularly dispersed. Anything may be used. As for the polymer latex according to the present invention, “synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing Co., Ltd. (1978))”, “application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara) Edited, published by Polymer Publishing Association (1993)), "chemistry of synthetic latex (written by Soichi Muroi, published by Polymer Publishing Society (1970))", and the like.

  The average particle diameter of the dispersed particles of the polymer latex is preferably in the range of 1 to 50,000 nm, more preferably about 5 to 1000 nm. Regarding the particle size distribution of the dispersed particles, those having a wide particle size distribution or monodispersed particle size distribution may be used.

  The acrylic resin polymer latex according to the present invention may be a so-called core / shell type polymer latex in addition to a normal uniform polymer latex. In this case, it may be preferable to change the glass transition temperature between the core and the shell.

  The minimum film-forming temperature (MFT) of the acrylic resin-based polymer latex according to the present invention is preferably −30 ° C. to 90 ° C., more preferably about 0 ° C. to 70 ° C. A film-forming auxiliary may be added to control the minimum film-forming temperature. A film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of a polymer latex. For example, “Synthetic Latex Chemistry (Souichi Muroi, published by Kobunshi Shuppankai (1970)” )"It is described in.

  In the present invention, even if the undercoat layer has a two-layer structure, the effect is exhibited. In that case, it is necessary to contain the water-soluble resin and the hardener in the amount of the present invention on the upper layer side.

  On the other hand, a conductive layer such as a conductive polymer-containing layer described in paragraph Nos. 0031 to 0073 of JP-A-7-20596 or a metal oxide-containing layer described in paragraph Nos. 0074 to 0081 of JP-A-7-20596 is used. It is preferable to provide it. The conductive layer may be coated on either side as long as it is on the plastic film support, but it is preferably coated on the opposite side of the image forming functional layer with respect to the support. When this conductive layer is provided, the chargeability is improved, the adhesion of dust and the like is reduced, and white spots failure during printing is greatly reduced.

  In addition, a plastic film support is used as the support according to the present invention, and a material such as a plastic film and a metal plate (eg, iron, stainless steel, aluminum) or paper coated with polyethylene (also referred to as a composite base material). ) May be used as appropriate. These composite substrates may be bonded together before forming the coating layer, may be bonded after forming the coating layer, or may be bonded immediately before being attached to the printing press.

  In the present invention, after applying the undercoat layer, an easy adhesion treatment may be performed. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment.

(Stiffness)
Since the printing plate material of the present invention is composed of a plastic support, it preferably has a stiffness in the above range. If the weight is less than 50 g, the printing plate material is not elastic, and if it exceeds 500 g, the elasticity is too strong. In any case, it is difficult to handle the printing plate material and attach the printing plate to the plate cylinder.

  In the present invention, the stiffness can be measured using a commercially available film stiffness tester (for example, “Stiffness Tester UT-100-230” or “Stiffness Tester UT-200GR” manufactured by Toyo Seiki Seisakusho Co., Ltd.). Specifically, both ends on the long side of a 20 cm × 10 cm sample placed on a flat table are brought close to the table, and 5 cm on both ends are fixed to the table, and the center is bent 1 cm above the table. Assume that the evaluation is based on the load when the top is pushed down with a needle and pushed down by 3 mm.

(Image forming layer)
The image forming layer of the present invention contains heat-fusible and / or heat-fusible fine particles.

  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. 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, 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 size 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 mass 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 diameter 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 is commercially available in a relatively high purity state at a low cost, and despite its high solubility in water, its hygroscopicity is very low, and on-press developability and The storage stability 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, 1-90 mass% of the whole layer is preferable, and 10-80 mass% is more preferable.

(Image formation)
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.

(Photothermal conversion material)
The hydrophilic layer, the lower layer, and the image forming layer of the present invention achieve high sensitivity by containing the following photothermal conversion material. In the present invention, the following metal oxide can be added to the hydrophilic layer as a photothermal conversion material.

  A material that exhibits black color 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 (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more of the aforementioned metals.

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

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

  Specifically, it is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. These are disclosed by methods disclosed in JP-A-8-27393, JP-A-9-25126, JP-A-9-237570, JP-A-9-241529, JP-A-10-231441, and the like. Can be manufactured.

  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-8-273393 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.

  The addition amount of these composite metal oxides is 20% or more and less than 40%, more preferably 25% or more and less than 39%, more preferably 25% or more and less than 30%, based on the total solid content of the hydrophilic layer. Range. When the addition amount is less than 20%, sufficient sensitivity cannot be obtained, and when it is 40% or more, ablation residue due to ablation occurs.

  In the present invention, 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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.

(Production of support)
Using terephthalic acid and ethylene glycol, polyethylene terephthalate having IV (inherent viscosity) = 0.66 dl / g (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) was obtained according to a conventional method. This is pelletized, 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. With respect to the drawing temperature, the first drawing was stretched 1.3 times at 102 ° C. and the second drawing was longitudinally stretched 2.6 times 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. Thereafter, the chuck portion of the tenter was slit, knurled at both ends, cooled to 40 ° C., and wound at 47.1 N / m. A biaxially stretched polyethylene terephthalate film having a thickness of 190 μm was thus 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. The thickness distribution of the obtained support was 3%.

(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 undercoat coating solution a in Table 1 below is applied to one surface so that the wet film thickness becomes 10 μm. After coating, it was dried at 180 ° C. for 4 minutes. Subsequently, undercoating treatment (8 W / m ² / min) was performed thereon, undercoat coating solution b shown in Table 2 below was applied to a wet film thickness of 11 μm, and dried at 180 ° C. for 4 minutes.

  The composition shown in Table 3 below was sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a lower hydrophilic layer coating solution.

  The composition shown in Table 4 below was sufficiently stirred and mixed using a homogenizer, and then filtered to prepare upper hydrophilic layer coating liquid levels 1 to 5.

(Application of lower and upper hydrophilic layers)
The lower hydrophilic layer coating solution is applied onto the support with the undercoat layer applied using wire bar # 5, and the drying zone set at 100 ° C. with a length of 15 m is transported at a speed of 15 m / min. I let it pass. Subsequently, the upper layer hydrophilic layer coating solution of levels 1 to 5 was applied using wire bar # 4, and passed through a drying zone set at 100 ° C. having a length of 30 m at a conveyance speed of 15 m / min. Sample No. 5 respectively corresponding to No. 5 1-5 were produced. The amount of each of the lower layer and the hydrophilic layer was 3.0 g / m ² and 1.8 g / m ² . The sample after coating was aged at 60 ° C. for 1 day.

(Preparation of image forming layer coating solution)
The image layers having the compositions shown in Table 5 below were respectively prepared as sample Nos. 1-5 coated on the upper hydrophilic layer using wire bar # 4, passed through a 30 m long drying zone set at 70 ° C. at a conveying speed of 15 m / min, and the image forming layer was passed through The formed lithographic printing plate material No. 01-05 were obtained. The amount of the image forming layer applied was 0.5 g / m ² . The lithographic printing plate material No. after coating 01-05 was aged at 50 ° C. for 2 days.

  The obtained planographic printing plate material No. 01 to 05 were cut to a width of 660 mm and wound around a paper core having an outer diameter of 76 mm for 30 m to obtain a rolled planographic printing plate material.

(Printing method)
Printing apparatus: Using a Lithlon 26P manufactured by Komori Corporation, printing was performed while changing the number of blanket automatic washings during initial printing for on-press development. Printing evaluation was performed using OK top coat for printing paper, Astro Mark 3 (manufactured by Nikken Chemical Research Co., Ltd.), 2% by mass, and ink for Values G manufactured by Dainippon Ink & Chemicals, Inc.

(Evaluation of printing durability)
The printing end point was determined at the stage when either a 3% dot missing in the image or a decrease in the density of the solid portion was confirmed, and the number of sheets was determined. The results are shown in Table 6.

  As is apparent from Table 6, the lithographic printing plate of the present invention is excellent in printing durability.

Claims (5)

A lithographic printing plate material in which a subbing layer, a hydrophilic layer, and an image forming layer are sequentially provided on a plastic support, and are developed on a printing press to form a final image. A lithographic printing plate material, wherein a water-soluble resin having a silanol group in the chain is introduced. The lithographic printing plate material according to claim 1, wherein the hydrophilic layer has a pH of 9 or more and less than 12. The lithographic printing plate according to claim 1 or 2, wherein at least one of a hydrophilic layer and an image forming layer provided in the lithographic printing plate material contains a photothermal conversion agent that converts near infrared rays into heat. material. The lithographic printing plate material according to any one of claims 1 to 3, wherein the hydrophilic layer is formed by a coating step and has a two-layer structure. An image forming method comprising forming an image of the lithographic printing plate material according to any one of claims 1 to 4 by using a thermal head or a thermal laser.