JP2007160668A - Lithographic printing plate material, its manufacturing method and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate material for a CTP style with good inking properties, superior in on-machine developing properties, and superior in printing wear, ground staining resistance during storing for a long period, scuff and stain resistance (scratch resistance) on non-imaging parts, its manufacturing method, and a printing method using the lithographic printing plate material. <P>SOLUTION: In the lithographic printing plate material with an undercoat layer and a thermal image forming layer on an aluminum substrate, the lithographic printing plate material is characterized in that the undercoat layer has an islands-in-sea structure consisting of a dispersing phase (island shape) containing a polymer fine particle and a continuous phase (sea shape) containing a water-soluble resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  At present, in the field of printing, printing by the CTP method has been performed with the digitization of print image data. However, this printing is inexpensive and easy to handle and is equivalent to a conventional so-called PS plate. Therefore, there is a demand for a printing plate material for a CTP system having the following printability.

  In particular, in recent years, it has direct imaging (hereinafter referred to as DI) performance that does not require development processing with a special agent, and can be applied to a printing press having this function, and has the same usability as the PS plate As a result, a general-purpose type processless plate is required.

  An infrared 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 and a heat fusion image layer on-machine development type.

  Examples of the ablation type include those 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. Can be mentioned.

  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. However, since contamination inside the exposure apparatus due to the ablated surface layer scattered matter becomes a problem, the exposure apparatus may require a special suction device, and the versatility of the exposure apparatus is low.

  On the other hand, development of a printing plate material that can form an image without causing ablation and does not require a development process or a wiping process using a special developer is also underway. For example, a binder of thermoplastic fine particles and a water-soluble polymer compound is used for a thermal image forming layer as disclosed in Japanese Patent Nos. 2938397, 2938397, 9-123387, 9-123388. And a CTP printing plate material that can be developed with dampening water or ink on a printing press. These on-press developable printing plate materials provide sharp dot shapes and high-definition images, and do not require a development process after exposure, and are excellent in environmental suitability.

  However, these printing plate materials have a problem that the printing durability is insufficient because the film strength of the hydrophilic layer and the image forming layer itself is weak. In response to these problems, a reactive thermoplastic resin is added to the image forming layer to improve it (for example, see Patent Documents 1 and 2). However, when the reactive thermoplastic resin is added, developability deteriorates and stains and scratches on non-image areas are likely to occur. Therefore, development of a printing plate material that has both printing durability and developability is achieved. Is strongly demanded.

Furthermore, a lithographic printing plate precursor having an image recording layer containing microcapsules encapsulating a polymerizable compound is known as a printing plate material that can be developed on-press without causing ablation (see, for example, Patent Document 3). There is also known an on-press developable lithographic printing plate precursor in which a photosensitive layer containing an infrared absorber, a radical polymerization initiator and a polymerizable compound is provided on a support. Furthermore, it is disclosed that an undercoat layer using a specific water-soluble resin is provided between the support and the image recording layer in order to achieve both on-press developability, stain and printing durability of the printing plate. (For example, refer to Patent Document 4). However, it has been found that the printing durability is not sufficient in the case of printing using powder, and developability and stains during long-term storage deteriorate due to the use of a polymerizable compound.
JP 2005-297233 A JP 2005-305690 A JP 2001-277740 A Kaikai 2002-365789

  The present invention has been made in view of the above problems, and its purpose is to achieve good ink deposition and excellent on-press developability, printing durability, stain resistance during long-term storage, and non-image area. An object of the present invention is to provide a lithographic printing plate material for the CTP system which is excellent in scratch stain resistance (scratch resistance), a production method thereof, and a printing method using the lithographic printing plate material.

  The above object of the present invention is achieved by the following configurations.

  1. In a lithographic printing plate material having an undercoat layer and a thermal image-forming layer on an aluminum support, the undercoat layer comprises a dispersed phase (island shape) containing polymer fine particles and a continuous phase (sea shape) containing a water-soluble resin. A lithographic printing plate material characterized by having a sea-island structure.

  2. In a lithographic printing plate material having an undercoat layer and a heat-sensitive image forming layer on an aluminum support, the undercoat layer has a rubbing frequency of 2 to 20 times required for peeling in a dampening test with a fountain solution. A lithographic printing plate material characterized by.

  3. 3. The lithographic printing plate material as described in 1 or 2 above, wherein the content of the water-soluble resin is 1 to 20% by mass based on the total mass of all components constituting the undercoat layer.

  4). The lithographic printing plate material according to any one of 1 to 3, wherein the undercoat layer contains polymer fine particles containing at least an acrylic resin or polyester.

  5. 5. The lithographic printing plate material as described in 4 above, wherein among all the monomer components forming the acrylic resin or polyester, 10 to 70 mol% of the monomer components are carboxylic acid, sulfonic acid and salts thereof.

  6). The lithographic printing plate material as described in any one of 1 to 5 above, wherein the heat-sensitive image forming layer is an on-press developable layer.

  7). The lithographic printing plate material as described in any one of 1 to 6, wherein the heat-sensitive image forming layer contains heat-meltable fine particles or heat-fusible fine particles.

  8). A method for producing a lithographic printing plate material, wherein an undercoat layer and a thermal imaging layer are coated in this order from the support side on a roughened aluminum support, wherein the undercoat layer comprises a polymer dispersion. A method for producing a lithographic printing plate material, wherein the lithographic printing plate material is coated with a liquid, and the drying temperature of the undercoat layer is 40 to 75 ° C.

  9. 9. The method for producing a lithographic printing plate material as described in 8 above, wherein the polymer component of the polymer dispersion is an acrylic resin or polyester.

  10. A lithographic printing plate material produced by the method described in 8 or 9 above.

  11. The lithographic printing plate material according to any one of 1 to 7 and 10 described above is subjected to image exposure with a laser beam, and then developed with dampening water or dampening water and printing ink on a lithographic printing machine, and printed. A printing method characterized by the above.

  With the above-described configuration of the present invention, the CTP system has excellent ink fillability, excellent on-press developability, and excellent printing durability, stain resistance during long-term storage, and scratch resistance (scratch resistance) in non-image areas. The lithographic printing plate material, the production method thereof, and the printing method using the lithographic printing plate material can be provided.

  The lithographic printing plate material of the present invention is a lithographic printing plate material having an undercoat layer and a thermal image-forming layer on an aluminum support. The undercoat layer contains a dispersed phase (island shape) containing polymer fine particles and a water-soluble component. It has a sea-island structure consisting of a continuous phase (sea shape).

  The present invention and components will be described in detail below.

(Undercoat layer)
(1) Sea-island structure The undercoat layer according to the present invention has a sea-island structure composed of a dispersed phase (island shape) containing fine polymer particles and a continuous phase (sea shape) containing a water-soluble resin. Such an undercoat layer occurs when the polymer fine particles and the water-soluble resin are not compatible with each other, and the polymer fine particles exist in the water-soluble resin as a spherical or flat spherical dispersed phase. Here, such a structure having a dispersed phase is called a sea-island structure. That is, in the present invention, the “sea-island structure” means a phase-separated structure shown in the first type of closed structure described in Chapter V, Item 5 of the Polymer Latex Introduction (by Soichi Muroi), A phase separation structure consisting of a discontinuous phase dispersed in a particulate form in the undercoat layer and a continuous phase existing outside the discontinuous phase.

  In the present invention, the observation of the sea-island structure is carried out by making a cross section of the undercoat layer obtained by cutting a lithographic printing plate with a microtome or the like, then taking a photograph with a scanning electron microscope (SEM), and dispersing the circular or elliptical shape. The size of the phase can be evaluated by an image analyzer. If the image is unclear when photographed, the cross-section of the undercoat layer is treated by, for example, solvent etching according to the method described in “Polymer Alloy and Polymer Blend” (LA UTRACKI, translated by Toshio Nishi; Tokyo Chemical Dojin). After shooting, a clearer image can be obtained.

  Such a sea-island structure has excellent on-press developability, printing durability, and soiling during long-term storage by regulating the content of water-soluble resin in the undercoat layer and the particle size and composition of the polymer particles. It can be made excellent in resistance and scratch stain resistance in non-image areas.

(2) Water-soluble resin The undercoat layer according to the present invention preferably contains 1 to 20% by mass of a water-soluble resin with respect to the total mass of all components constituting the undercoat layer. More preferably, it is 3 to 15%. If it is less than 1%, the developability and scratches on the non-image area are deteriorated, which is not preferable. If it exceeds 20%, the printing durability deteriorates.

  Specific examples of the water-soluble resin of the undercoat layer according to the present invention include natural gum, gum arabic, water-soluble soybean polysaccharide, fiber derivative (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), Synthetic polymers such as denatured products, white dextrin, pullulan, enzymatically degraded etherified dextrin, polyvinyl alcohol (preferably having a saponification degree of 70 mol% or more), polyacrylic acid, alkali metal salt or amine salt thereof, polyacrylic acid Copolymer, its alkali metal salt or amine salt, polymethacrylic acid, its alkali metal salt or amine salt, vinyl alcohol / acrylic acid copolymer and its alkali metal salt or amine salt, polyacrylamide, its copolymer, poly Hydroxyethyl acrylate, polyvinyl Loridone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, its alkali metal salt or amine salt, poly-2- Examples thereof include acrylamido-2-methyl-1-propanesulfonic acid copolymer, alkali metal salt or amine salt thereof. 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.

(3) Polymer fine particles The polymer fine particles according to the present invention are preferably those in which a thermoplastic compound is in the form of particles. That is, it is preferable to use a heat-meltable material or a heat-fusible material in the form of particles.

  The heat-meltable particles are 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., stains and developability during long-term storage are problematic, and when the melting point is higher than 300 ° C., the printing durability is lowered.

  Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. 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.

  Examples of the heat-fusible particles used in the present invention include thermoplastic hydrophobic polymer particles, and the mass average molecular weight (Mw) of the polymer is in the range of 10,000 to 1,000,000. Preferably there is.

  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) copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene and the like, copolymers thereof, polyester modified with the above-mentioned vinyl polymer, etc. Is mentioned. Among these, acrylic resins, in particular, (meth) acrylic acid copolymers, polyesters and polyesters modified with the above-mentioned vinyl polymers are preferable in terms of exhibiting the effects of the present invention.

  In the present invention, in particular, the composition of all the monomer components forming the acrylic resin or polyester includes an acid component such as carboxylic acid or sulfonic acid or a salt component thereof as the monomer component, so that on-press developability is improved. This is preferable. The amount of the acid component is preferably 10 to 70 mol% of the total monomer components of each resin. If it is less than 10%, the developability and scratches on the non-image area deteriorate, which is not preferable. On the other hand, if it exceeds 70%, printing durability deteriorates, so care must be taken.

  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 for making a polymer polymer polymerized by a solution polymerization method or a gas phase polymerization method into fine particles, a solution obtained by dissolving the polymer in an organic solvent is sprayed into an inert gas and dried. Examples thereof include a method of dissolving a polymer in a water-immiscible organic solvent, dispersing the solution in water or an aqueous medium, and distilling off the organic solvent 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. Further, the composition of the heat fusible particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

  The average particle size of the polymer fine particles is preferably 0.01 to 5 μm, more preferably 0.1 to 2 μm, still more preferably 0.2 to 1 μm in order to achieve both on-press developability and printing durability. is there.

  In order to provide a subbing layer in the form of particles, it is important that the polymer dispersion, i.e. latex (polymer emulsion), is applied onto the aluminum support and not completely melted or fused. Therefore, the drying temperature when applying the undercoat layer needs to be 40 to 75 ° C. It is particularly preferable to dry at 50 to 75 ° C. When it is less than 40 ° C., the coating film strength is not sufficient, which is not preferable. If the temperature exceeds 75 ° C., the polymer fine particles are melted or fused, and it becomes difficult to control the effect of the invention.

  Any known coating method can be applied as a method for applying the undercoat layer. For example, kiss coat method, reverse coat method, die coat method, reverse kiss coat method, offset gravure coat method, Mayer bar coat method, roll brush method, spray coat method, air knife coat method, impregnation method, curtain coat method, etc. alone or in combination To apply.

  The thickness of the undercoat layer is preferably 0.05 to 2.0 μm from the viewpoint of adjusting the effect of the present invention. More preferably, it is 0.10 to 1.0 μm. If it is less than 0.05 μm, the desired adhesiveness cannot be obtained, and the printing durability is deteriorated. On the other hand, if it exceeds 2.0 μm, the developability is deteriorated.

(Abrasion peeling resistance)
In the undercoat layer according to the present invention, the number of times required for rubbing and peeling with dampening water is preferably 2 to 20 times in the following experimental method. Particularly preferably, it is 3 to 10 times.

  The rubbing peeling experiment with the fountain solution of the undercoat layer according to the present invention was carried out using a 200 mm square undercoat layer coated aluminum dampening solution (ASTROMARK 3 (manufactured by Nikken Chemical Laboratories) 2% by mass) It was the number of times required for peeling off the undercoat layer when the surface was rubbed with a sponge and then rubbed with a sponge.

  What peels only by being immersed is not preferable because the printing durability is not sufficient even when exposure printing is actually performed. On the other hand, those that do not peel over 20 times are not preferred because of poor developability.

(Thermal image forming layer)
The thermal image forming layer is a layer that can form an image by heating, and is a thermoplastic compound such as a heat-fusible material or heat-fusible material, or a material that changes from hydrophilic to hydrophobic by heating (hydrophobic precursor). including. The heating method is a method using heat generated by exposure to actinic rays, and an image forming method using heat generated by laser light exposure is particularly preferable.

  The heat-sensitive image forming layer according to the present invention has a great effect when the image formation is capable of on-press development. Note that “on-press development is possible” means that after printing plate material is image-exposed, it can be developed with lithographic dampening water or dampening water and printing ink on the printing press without any particular development process. It means that it can be transferred to the process.

  The heat-sensitive image forming layer of the present invention preferably contains a thermoplastic compound as thermoplastic particles in the form of particles.

  That is, it is preferable to use a heat-meltable material or a heat-fusible material in the form of particles as heat-meltable particles or heat-fusible particles.

  As one of the preferred embodiments of the thermal image forming layer according to the present invention, it is also preferable that the thermal image forming layer contains a hydrophobized precursor.

  As the hydrophobizing precursor, a polymer that changes from hydrophilicity (water-soluble or water-swellable) to hydrophobicity by heat can be used. Specific examples include polymers containing aryl diazosulfonate units disclosed in Japanese Patent Application Laid-Open No. 2000-56449.

  The heat-meltable particles are particles made of a material that has a low viscosity when melted among thermoplastic materials and is generally classified as a 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 particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 μm, more preferably 0.1 μm, from the viewpoint of on-press developability and resolution. ~ 3 μm.

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

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

  In the heat-sensitive image forming layer according to the present invention, it is particularly preferable that the heat-meltable particles are contained in a microcapsule form.

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

  Examples of the heat-fusible particles used in the present invention include thermoplastic hydrophobic polymer particles, and there is no specific upper limit for the softening temperature of the polymer particles, but the temperature is the same as that of the polymer particles. It is preferable that the temperature is lower than the decomposition temperature. 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 for making a polymer polymer polymerized by a solution polymerization method or a gas phase polymerization method into a fine particle, a solution is sprayed in an inert gas in an organic solvent of the polymer polymer and dried to make a fine particle, 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 particles are preferably dispersible in water, and the average particle size is preferably from 0.01 to 10 μm, more preferably from the viewpoint of on-press developability and resolution. ~ 3 μm.

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

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

  In the heat-sensitive image forming layer of the present invention, it is particularly preferable that the heat-fusible particles are contained in a microencapsulated form.

  Examples of the microcapsule include microcapsules enclosing a hydrophobic material described in JP-A No. 2002-2135 and JP-A No. 2002-19317.

  The microcapsules preferably have an average diameter of 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm.

  The thickness of the wall of the microcapsule is preferably 1/100 to 1/5 of the diameter, and more preferably 1/50 to 1/10.

  The content of the microcapsule is 5 to 100% by mass of the entire heat-sensitive image forming layer, preferably 20 to 95% by mass, and more preferably 40 to 90% by mass.

  Known materials and methods can be used as the material for the wall of the microcapsule and the method for producing the microcapsule. For example, known materials and methods described in “New edition microcapsules, production method, properties, and application” (written by Tamotsu Kondo, Masumi Koishi / Sankyo Publishing Co., Ltd.) or cited references are used. be able to.

  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 heat-sensitive image forming layer according to the present invention can further contain a water-soluble material. By including the water-soluble material, when the thermal image forming layer in the unexposed area is removed with 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. The water-soluble resin that can be used in the heat-sensitive image forming layer is selected from hydrophilic natural polymers and synthetic polymers.

  Specific examples of water-soluble resins preferably used in the present invention include natural gums, gum arabic, water-soluble soybean polysaccharides, fiber derivatives (for example, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), and modifications thereof. In the case of synthetic polymers such as body, white dextrin, pullulan, enzymatically degraded etherified dextrin, polyvinyl alcohol (preferably having a saponification degree of 70 mol% or more), polyacrylic acid, its alkali metal salt or amine salt, and polyacrylic acid Polymer, 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, polyacrylamide, copolymer thereof, polyhydroxy Ethyl acrylate, Polyvinyl Lupyrrolidone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, alkali metal salt or amine salt thereof, poly-2 -Acrylamido-2-methyl-1-propanesulfonic acid copolymer, its alkali metal salt or amine salt. 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.

  The content of the water-soluble resin in the heat-sensitive image forming layer is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass based on the entire layer.

(Other materials that can be included in the thermal image forming layer)
The thermal image forming layer used in the present invention may further contain the following materials.

  In the present invention, it is a preferred embodiment that the thermal image forming layer contains an infrared absorbing dye. When used in combination with the metal oxide particles, the film strength of the thermal image forming layer can be further improved, and the printing durability using powder and the resistance to foreign matters when using paper with a lot of paper dust, etc. It can be improved further.

  Infrared absorbing dyes that can be used in the present invention include general infrared absorbing dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinones. And organic compounds such as phthalocyanines, phthalocyanine-based, naphthalocyanine-based, 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 And 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 preferably 0.1% by mass or more and less than 10% by mass, and preferably 0.3% by mass or more and less than 7% by mass with respect to the total solid content of the image forming layer in terms of preventing ablation. More preferably, it is the range of 0.5 mass% or more and less than 6 mass%.

The amount per the image formation layer is preferably 0.01-5 g / m ^2, more preferably from 0.1 to 3 g / m ^2, particularly preferably from 0.2 to 2 g / m ^2.

(Protective layer)
A protective layer may be provided on the thermal image forming layer. As a material used for the protective layer, the above-mentioned water-soluble resin can be preferably used. Moreover, the hydrophilic overcoat layer described in JP2002-19318A or JP2002-86948A 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.

(Aluminum support)
The support that can be used for the lithographic printing plate material of the present invention is an aluminum plate. In this case, a pure aluminum plate, an aluminum alloy plate, or the like may be used.

  Various aluminum alloys can be used as the support, such as alloys of aluminum and metals such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, etc. Aluminum plates manufactured by various rolling methods can be used. In addition, a recycled aluminum plate obtained by rolling recycled aluminum ingots such as scrap materials and recycled materials that are becoming popular in recent years can also be used.

  The support that can be used for the lithographic printing plate material of the present invention is preferably subjected to a degreasing treatment in order to remove rolling oil on the surface prior to roughening (graining treatment). As the degreasing treatment, a degreasing treatment using a solvent such as trichlene or thinner, an emulsion degreasing treatment using an emulsion such as kesilon or triethanol, or the like is used. In addition, an alkaline aqueous solution such as caustic soda can be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed only by the degreasing treatment can be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is generated on the surface of the support. In this case, the substrate is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof and desmutted. It is preferable to perform the treatment.

  Next, a roughening process is performed. In the present invention, AC electrolytic surface roughening treatment is performed in an electrolytic solution mainly composed of hydrochloric acid, but prior to that, mechanical surface roughening treatment may be performed.

The mechanical roughening method is not particularly limited, but a brush polishing method and a honing polishing method are preferable. The roughening by the brush polishing method is, for example, by rotating a rotating brush using a bristle having a diameter of 0.2 to 0.8 mm, and for example, volcanic ash particles having a particle size of 10 to 100 μm on water. While supplying the uniformly dispersed slurry, the brush can be pressed. The roughening by honing polishing is performed by, for example, uniformly dispersing volcanic ash particles having a particle size of 10 to 100 μm in water, injecting pressure from a nozzle, and causing the surface to collide obliquely with the support surface. Can do. Further, for example, abrasive particles having a particle size of 10 to 100 μm are applied to the support surface so as to be present at a density of 2.5 × 10 ³ to 10 × 10 ³ particles / cm ² at intervals of 100 to 200 μm. Roughening can also be performed by laminating the sheets and applying a pressure to transfer the rough surface pattern of the sheet.

After the surface is roughened by the mechanical surface roughening method, it is preferable to immerse in an aqueous solution of acid or alkali in order to remove the abrasive that has digged into the surface of the support, formed aluminum scraps, and the like. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an aqueous alkali solution such as sodium hydroxide. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. After the immersion treatment with an alkaline aqueous solution, it is preferable to carry out a neutralization treatment by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

After the electrolytic surface roughening treatment is performed in the above-described electrolytic solution mainly composed of an acid, it is preferably immersed in an acid or alkali aqueous solution in order to remove aluminum scraps on the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an aqueous solution of phosphoric acid or sodium hydroxide. The amount of aluminum dissolved on the surface is preferably 0.1 to ² g / m ² . In addition, it is preferable that after the immersion treatment with an alkaline aqueous solution, neutralization treatment is performed by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

Following the roughening treatment, an anodizing treatment is performed. There is no restriction | limiting in particular in the method of the anodizing process used by this invention, A well-known method can be used. An oxide film is formed on the support by anodization. The anodizing treatment is generally carried out by direct current electrolysis using sulfuric acid or phosphoric acid or a mixed aqueous solution of both as the electrolytic solution. In the present invention, the anodic oxidation treatment is preferably performed using sulfuric acid as the electrolytic solution. The concentration of sulfuric acid is preferably 5 to 50% by mass, particularly preferably 10 to 35% by mass. The temperature is preferably 10 to 50 ° C. The treatment voltage is preferably 18V or more, and more preferably 20V or more. Current density is preferably 1~30A / dm ^2. Quantity of electricity is preferably from 100 to 500 C / dm ^2.

The amount of anodic oxidation coating formed is suitably 1 to 50 mg / dm ² , preferably 10 to 40 mg / dm ² . The anodized coating amount is obtained by, for example, immersing an aluminum plate in a chromic phosphate solution (85% phosphoric acid solution: 35 ml, prepared by dissolving 20 g of chromium (IV) oxide in 1 L of water) to dissolve the oxide film, It is obtained from mass change measurement before and after dissolution of the coating on the plate. Micropores are generated in the anodized film, and the density of the micropores is preferably 400 to 700 / μm ^{2, and} more preferably 400 to 600 / μm ² .

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

  Furthermore, in this invention, after performing these processes, you may perform a hydrophilic treatment as needed. Hydrophilization treatment is not particularly limited, but a water-soluble resin such as polyvinylphosphonic acid, a polymer and copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt (for example, zinc borate) or Undercoat with yellow dye or amine salt can be used. Furthermore, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-5-304358 is covalently used. Preferably, the support surface is hydrophilized with polyvinylphosphonic acid. The treatment is not limited to a coating method, a spray method, a dip method, or the like, but a dip method is suitable for making the equipment inexpensive. In the case of a dip type, it is preferable to treat polyvinylphosphonic acid with a 0.05 to 3% aqueous solution. The treatment temperature is preferably 20 to 90 ° C., and the treatment time is preferably 10 to 180 seconds. After the treatment, it is preferable to perform a squeegee treatment or a water washing treatment in order to remove the excessively laminated polyvinylphosphonic acid. Furthermore, it is preferable to perform a drying process. As a drying temperature, 20-95 degreeC is preferable.

  The aluminum support is usually used after degreasing with an alkali, an acid, a solvent, or the like in order to remove the oil used during rolling and winding existing on the surface of the aluminum support. As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable.

  Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface. For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent, or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. Moreover, it can also use combining an anodizing process and the said immersion or application | coating process. Moreover, the aluminum plate roughened by the well-known method can also be used.

(exposure)
In the present invention, it is preferable to form an image on a lithographic printing plate material using a laser beam. Among these, it is particularly preferable to form an image by exposure with a thermal laser.

  For example, scanning exposure using a laser that emits light in the infrared and / or near infrared region, that is, emits light in the wavelength range of 700 to 1500 nm is preferable. 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.

  An apparatus suitable for scanning exposure according to the present invention is any apparatus that 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. Also good.

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

  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.

(printing)
A general lithographic printing method using a dampening solution and printing ink can be applied to the printing method of the present invention.

  As a printing method of the present invention, it is particularly preferable to use a fountain solution that does not contain isopronol as the fountain solution (the content is not more than 0.5% by mass with respect to water). It is.

  The printing plate material on which an image is formed as described above can be printed without going through a development process.

  That is, in a preferred embodiment, the printing plate material of the present invention is subjected to image exposure with a laser beam and then developed with dampening water or dampening water and printing ink on a lithographic printing machine.

  The printing plate material after image formation is directly attached to the plate cylinder of the printing press, or the image forming is performed after the printing plate material is attached to the plate cylinder of the printing press, and the water supply roller and / or ink supply is performed while rotating the plate cylinder. The non-image portion of the image forming layer can be removed by bringing the roller into contact with the printing plate material.

  The removal of the non-image area, a so-called on-press development method will be described below.

The removal of the non-image part (unexposed part) 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, as in the example given below. Alternatively, it can be performed by various other sequences. In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.
(1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, then an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then printing is performed. Start.
(2) As a sequence for starting printing, an ink roller is brought into contact with the plate cylinder to make one to several tens of turns, then a watering roller is brought into contact with the plate cylinder to make one to several tens of turns, and then printing is performed. Start.
(3) As a sequence for starting printing, the watering roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder one to several tens of times, and then printing is started.

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

(Preparation of base material)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm is immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolution amount becomes 2 g / m ² , and washed with water. Then, it was immersed in a 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 sinusoidal alternating current and a peak current density of 60 A / dm ^2. went. At this time, the distance between the electrode and the sample surface 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 pause time of 4 seconds was provided between each surface roughening treatment.

After electrolytic surface roughening, it is immersed in a 1% by mass sodium hydroxide aqueous solution kept at 50 ° C. so that the dissolution amount including the smut of the roughened surface becomes 0.2 g / m ^2. After etching and washing with water, it was immersed in a 10% by mass sulfuric acid aqueous solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water. Next, anodization was performed in a 20% by mass 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 2.0 mass% aqueous sodium hydrogen carbonate solution kept at 50 ° C. for 30 seconds, washed with water, and then dried at 80 ° C. for 5 minutes. Next, the substrate 1 was immersed in a 5.0% by mass citric acid aqueous solution maintained at 75 ° C. for 30 seconds, washed with water, and then dried at 80 ° C. for 5 minutes to obtain a substrate 1.

  As a result of measuring the surface roughness of the base material 40 times using RST Plus manufactured by WYKO, Ra was 0.57 μm.

(Undercoat layer)
The undercoat layer coating solution having the composition shown in Table 2 below was applied to the base material prepared above using a wire bar so that the coating mass was 10 g / m ^2, and the length was set to 70 ° C. with a length of 30 m. The substrate was passed through the drying zone at a conveyance speed of 15 m / min to produce a substrate with an undercoat layer.

(Preparation of image forming layer coating solution)
The image forming layer coating solution having the composition shown in Table 3 below was applied to the base material having the undercoat layer prepared above using a wire bar so that the dry mass was 0.55 g / m ^2, and the length was 30 m. Was passed through the drying zone set at 70 ° C. at a conveyance speed of 15 m / min to form a thermal image forming layer. The sample after coating was aged at 50 ° C. for 2 days to obtain a lithographic printing plate material.

  The lithographic printing plate material was cut into 670 mm × 530 mm to obtain a sheet-like lithographic printing plate material.

  The material in the undercoat layer was changed as shown in Table 4, and a sheet-like lithographic printing plate material was produced in the same manner as in the production of the lithographic printing plate material.

<Evaluation>
(Exposure method)
The printing plate sample was cut in accordance with the exposure size, and then wound around the exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm is used for exposure, and the exposure energy is 200 mJ / cm ² , and 2,400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines. A formed printing plate sample was formed.

(Printing method)
Printing device: DAIYA1-F manufactured by Mitsubishi Heavy Industries, Ltd., fountain solution Astro Mark 3 (manufactured by Nikken Chemical Research Co., Ltd.), 2% by mass, ink is Toyo High Unity M Red (manufactured by Toyo Ink) Were prepared and evaluated for printing. Printing was performed using coated paper except for evaluation of printing durability. At the time of front printing, powder (trade name: Nikka Rico M (manufactured by Nikka Co., Ltd.)) was used and sprayed on the powder scale 10 of the printing apparatus.

(On-press developability: evaluation of printing)
Good S / N ratio at the time of printing (the non-image area has no background stain, that is, the non-image area of the image forming layer is removed on the printing machine, and the density of the image area is within an appropriate range. In particular, the number of printed sheets until a printed matter having a development defect due to scratches on the image layer due to the mat material of the backcoat layer was obtained was measured and used as an on-press developability index. The smaller the number of waste paper, the better. There are practical problems with 40 sheets or more.

(Print life)
Printing evaluation was performed using a backing paper printed on the above printing conditions using high-quality paper. 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, the number of sheets was determined, and this number was used as an index of printing durability.

(Scratch resistance (ink adhesion))
Before the exposure, the material was rubbed with the nail of the index finger, and the actual damage degree on the 20th printed sheet was evaluated according to the following rank, which was taken as one of the indexes of scratch resistance of the non-image area.

Adhesion of ball-point pen ink on non-image area after development:
◯: No ink is attached △: Slightly ink is attached △: Slightly ink is attached △ ×: Ink is attached at the same concentration as the 50% mesh portion X: Solid Ink adheres at the same density as the part (stain)
As a soiling property during long-term storage, the printing plate material is stored for 3 days in an atmosphere of 40 ° C. and 80% RH, and after exposure, the color difference between the non-image area of the printed material after printing 10,000 sheets and paper white, Measurement was made using a color meter SPM-100 manufactured by GretagMacbeth, and the background stain was evaluated by a color difference as an index. If the color difference (ΔE) is 0.5 or more, there is a practical problem.

  The results are shown in Table 3. In addition, the number of rubbing in Table 3 was evaluated according to the above-described rubbing peeling test method.

  From Table 3, it can be seen that the planographic printing plate material of the present invention is excellent in on-press developability, printing durability, long-term storage stain resistance, and scratch resistance.

Claims (11)

In a lithographic printing plate material having an undercoat layer and a thermal image-forming layer on an aluminum support, the undercoat layer comprises a dispersed phase (island shape) containing polymer fine particles and a continuous phase (sea shape) containing a water-soluble resin. A lithographic printing plate material characterized by having a sea-island structure. In a lithographic printing plate material having an undercoat layer and a heat-sensitive image forming layer on an aluminum support, the undercoat layer has a rubbing frequency of 2 to 20 times required for peeling in a dampening test with a fountain solution. A lithographic printing plate material characterized by. The lithographic printing plate material according to claim 1 or 2, wherein a content of the water-soluble resin is 1 to 20% by mass with respect to a total mass of all components constituting the undercoat layer. The lithographic printing plate material according to any one of claims 1 to 3, wherein the undercoat layer contains fine polymer particles containing at least an acrylic resin or polyester. 5. The lithographic printing plate material according to claim 4, wherein among all the monomer components forming the acrylic resin or polyester, 10 to 70 mol% of the monomer components are carboxylic acid, sulfonic acid and a salt thereof. The lithographic printing plate material according to any one of claims 1 to 5, wherein the heat-sensitive image forming layer is an on-press developable layer. The lithographic printing plate material according to any one of claims 1 to 6, wherein the heat-sensitive image forming layer contains heat-meltable fine particles or heat-fusible fine particles. A method for producing a lithographic printing plate material, wherein an undercoat layer and a thermal imaging layer are coated in this order from the support side on a roughened aluminum support, wherein the undercoat layer comprises a polymer dispersion. A method for producing a lithographic printing plate material, wherein the lithographic printing plate material is coated with a liquid, and the drying temperature of the undercoat layer is 40 to 75 ° C. The method for producing a lithographic printing plate material according to claim 8, wherein the polymer component of the polymer dispersion is an acrylic resin or polyester. A lithographic printing plate material produced by the method according to claim 8 or 9. After the lithographic printing plate material according to any one of claims 1 to 7 and claim 10 is image-exposed with laser light, development is performed with dampening water or dampening water and printing ink on a lithographic printing machine, A printing method characterized by printing.