JP2008100426A - Processing method of lithographic printing plate material and lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-press developing type lithographic printing plate material, which develops neither misregistering in multicolor printing nor mismounting and makes the handling information of the lithographic printing plate material easy to read, and the processing method of the lithographic printing plate material which develops no accident due to slippage at the mounting on the printer. <P>SOLUTION: In the processing method of the lithographic printing plate material having an image forming layer, where at least an area pattern-exposed by pattern heating or light energy becomes nonremovable at the printing process of the printing machine, on a base material with a hydrophilic surface, the image forming layer in the region belonging to some part of the peripheral side part of the lithographic printing plate material is removed before the process, in which the lithographic printing plate material is mounted onto the printing machine to conduct printing. The lithographic printing plate is treated according to the processing method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a processing method of a lithographic printing plate material and a lithographic printing plate, and in particular, a processing method of a lithographic printing plate material (hereinafter also simply referred to as a printing plate material) capable of forming an image by a computer-to-plate (CTP) method, and It relates to a lithographic printing plate (hereinafter also simply referred to as a printing plate).

  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, there has been a demand for a printing plate material that does not require development processing using a processing solution containing a special agent (for example, alkali, acid, solvent, etc.) and can be applied to a conventional printing machine. Phase change type printing plate material that does not require water, printing plate material that is processed with water or a substantially neutral processing liquid mainly composed of water, and development processing is performed at an initial stage of printing on a printing press. There are known printing plate materials called chemical-free type printing plate materials and processless type printing plate materials, such as printing plate materials that do not require a process.

  The above-described printing plate materials that do not require any development processing and processless type printing plate materials that are developed on a printing press perform punching necessary for attachment to the printing press after exposure, so that they are the same as conventional PS In addition, it is required to have so-called exposure visible image quality.

  In addition, the thermal laser recording method having a wavelength of near infrared to infrared is mainly used for image formation of processless type printing plate materials. The thermal processless plate that can form an image by this method is roughly divided. An ablation type, a heat fusion image layer on-machine development type, and a phase change type are known.

  On the other hand, the following printing plate materials are known as printing plate materials obtained by imparting exposure visibility to these processless type printing plate materials.

  For example, a layer containing a heat-sensitive coloring material such as a leuco dye and its developer in the image forming layer, a polymer compound having a functional group that generates sulfonic acid by heat, and a compound that changes color by the generated acid A printing plate material having a layer containing an IR-dye that can change its optical density by exposure of an imaging element (See, for example, Patent Document 3) A printing plate material having a hydrophilic overcoat layer that can be removed on a printing press, containing 20% by mass or more of a cyanine infrared absorbing dye capable of changing an optical density by exposure. (For example, see Patent Document 4).

However, in giving exposure visible images of these printing plate materials, the contrast is insufficient for visual discrimination, or even when visible immediately after image formation, the contrast gradually increases under storage in a bright room. Disappearing makes it difficult to discriminate and sometimes causes a mounting error when handling multiple versions of multicolored printed matter. In addition, on-press development type printing plate materials can be added to the surface by adding a lubricant to make the surface slippery to prevent the occurrence of scratches on the plate surface during handling, or by adding fine particles protruding from the plate surface. In many cases, unevenness is provided to prevent external force from reaching the image forming layer. In such a case, when the printing plate is attached to the printing press, the fixing of the plate becomes unstable, and the printing plate surface gradually shifts as the printing process proceeds. The occurrence of was a problem.
JP 2000-225780 A Japanese Patent Laid-Open No. 2002-211150 JP-A-11-240270 JP 2002-205466 A

  An object of the present invention is to provide a lithographic printing plate material in which on-press development type lithographic printing plate material has no misregistration in multicolor printing, is not attached incorrectly, and handling information of the lithographic printing plate material is easy to read, and a processing method thereof. It is in. It is another object of the present invention to provide a method for processing a planographic printing plate material that does not cause an accident due to slippage when attached to a printing press.

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

  1. In the processing method of a lithographic printing plate material having an image forming layer in which at least an imagewise exposed region by imagewise heating or light energy cannot be removed in a printing process of a printing machine on a substrate having a hydrophilic surface, A processing method for a lithographic printing plate material, comprising removing the image forming layer in a partial region around the lithographic printing plate material before the step of attaching the lithographic printing plate material to a printing machine and performing printing.

  2. The method for processing a lithographic printing plate material according to 1 above, wherein the region from which the image forming layer is removed is a non-printing region.

  3. 3. The method for processing a lithographic printing plate material according to 1 or 2, wherein the region from which the image forming layer is removed is a holding portion or a holding bottom portion of the lithographic printing plate material when attached to a printing press.

  4). 4. The method for processing a lithographic printing plate material according to any one of 1 to 3, wherein an image is recorded imagewise by heat or light energy in a region from which the image forming layer is removed.

  5. A lithographic printing plate which is processed by the method for processing a lithographic printing plate material according to any one of 1 to 4 above.

  According to the present invention, a processing method of a lithographic printing plate material that is easy to read the handling information of the lithographic printing plate material without misregistration of multi-colored printing and wrong mounting of the on-press development type lithographic printing plate material, and when installed in a printing press In addition, it was possible to provide a method for processing a lithographic printing plate material that does not cause an accident due to slippage.

  The present invention will be described in more detail.

[Process for processing lithographic printing plate material of the present invention]
The processing method of the lithographic printing plate material of the present invention removes the image forming layer in a partial region of the peripheral portion of the lithographic printing plate material before the step of printing by attaching the lithographic printing plate material to a printing machine. The area to be removed is preferably a non-printing area, or a holding portion or a holding bottom portion of a planographic printing plate material when attached to a printing press.

  The treatment method of the present invention is carried out by bringing it into contact with a liquid containing water as a main component. As a method for bringing it into contact, a method of immersing in a treatment tank containing this liquid, or spraying this liquid from a nozzle or the like to make contact After applying to the surface using a coater such as a wire bar, wipe with a wet material such as cloth such as waste cloth or gauze, tissue paper, cellulose sponge, etc. In the present invention, a method of wiping after application of a spray coating method and a method of rubbing with a water-containing material are preferably applicable.

  The temperature of the liquid used is preferably 5 ° C to 60 ° C, particularly preferably 10 ° C to 50 ° C. The pretreatment time is preferably 1 second to 10 minutes, and particularly preferably 1 second to 1 minute.

  In the present invention, when there is an image-wise exposed portion in the region of the image forming layer to be removed, the image forming layer remains in the image-like manner, thereby forming a visible image. As this image information, for example, color information of the printing plate and characters and symbols representing the upper and lower sides of the printing plate are added, so that it is easy to work without making a mistake in the attachment position of the multicolor printing. In addition, when the image forming layer area to be removed is the gripping portion or the gripping bottom portion of the printing plate, the frictional force is reduced by removing the lubricant or the mat material in the image forming layer that causes the slip. In addition, the occurrence of deviation after being attached to the printing press is greatly suppressed. As another aspect, by removing the image forming layer at the ends of both sides of the other pair, not the gripping edge and the gripping edge of the printing plate, the residual components of the image forming layer fixed by pressure during cutting of the printing plate are removed. It is possible to prevent so-called “picture frame stains” that attach unnecessary printing ink and contaminate the printed matter.

〔Base material〕
The substrate having a hydrophilic surface according to the present invention can be obtained by a method of hydrophilizing the surface of the substrate or a method of providing a hydrophilic layer on the substrate.

  As a base material which concerns on this invention, the well-known material used as a base material of a printing plate can be used.

  For example, a metal plate, a plastic film, paper treated with a polyolefin, a composite base material obtained by appropriately bonding the above materials, and the like can be given. The thickness of the base material is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface. As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with an application layer, you may perform an easily bonding process and application | coating of an undercoat layer 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, followed by sufficient drying can be used. 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 base material roughened by the well-known method, what is called an aluminum grain can also be used as a base material which has a hydrophilic surface.

  Aluminum substrates that can be used for the printing plate material of the present invention include substrates made of pure aluminum and aluminum alloys. Various aluminum alloys can be used. For example, an alloy of a metal such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, and aluminum is used.

  The aluminum substrate is preferably subjected to a degreasing treatment in order to remove the rolling oil on the aluminum surface prior to the roughening 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 sodium hydroxide, potassium hydroxide, sodium carbonate, sodium phosphate or the like can be used for the degreasing treatment. When an alkaline aqueous solution 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 is used for the degreasing treatment, it is preferable to perform a neutralization treatment by immersing in an acid such as phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid, chromic acid, or a mixed acid thereof. When electrolytic surface roughening is performed after the neutralization treatment, it is particularly preferable to match the acid used for neutralization with the acid used for electrolytic surface roughening.

  As the roughening of the substrate, an electrolytic surface roughening treatment is carried out by a known method, but as a pretreatment, roughening by appropriately combining chemical roughening or mechanical roughening with an appropriate amount of treatment. Processing may be performed.

  Chemical roughening uses an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium phosphate as in the degreasing treatment. After the treatment, it is preferable to carry out a neutralization treatment by dipping in an acid such as phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid, chromic acid, or a mixed acid thereof. When electrolytic surface roughening is performed after the neutralization treatment, it is particularly preferable to match the acid used for neutralization with the acid used for electrolytic surface roughening.

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

  A mechanically roughened substrate is immersed in an aqueous solution of acid or alkali to remove abrasives, aluminum scraps, etc. that have digged into the surface of the substrate, or to control the pit shape. It is preferable to etch the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, and hydrochloric acid. Examples of the base include sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium phosphate. Among these, it is preferable to use an alkaline aqueous solution.

  By using an abrasive having a particle size finer than # 400 for the mechanical surface roughening treatment, and performing an etching treatment with an alkaline aqueous solution after the mechanical surface roughening treatment, an intricate rough surface by the mechanical surface roughening treatment. The structure can be a smooth uneven surface. For this reason, even when the image forming layer of the present invention is provided, a relatively long wavelength undulation of several μm to several tens of μm can be formed without impairing the on-press developability. By adding the crystallization treatment, it is possible to obtain an aluminum substrate that has good printing performance and contributes to improved printing durability. In addition, the amount of electricity during the electrolytic surface roughening treatment can be reduced, leading to cost reduction.

  When the above is immersed in an alkaline aqueous solution, it is preferably immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof for neutralization.

  When the electrolytic surface-roughening treatment is performed after the neutralization treatment, it is particularly preferable that the acid used for neutralization is matched with the acid used for the electrolytic surface-roughening treatment.

  The electrolytic surface roughening treatment is generally a surface roughening using an alternating current in an acidic electrolyte. As the acidic electrolytic solution, those used in a general electrolytic surface roughening method can be used, but a hydrochloric acid-based or nitric acid-based electrolytic solution is preferably used, and in the present invention, a hydrochloric acid-based electrolytic solution is particularly preferable.

  Various waveforms such as a rectangular wave, a trapezoidal wave, and a sawtooth wave can be used as the power supply waveform used for electrolysis, and a sine wave is particularly preferable.

  Further, a divided electrolytic surface roughening treatment as disclosed in JP-A-10-869 can also be preferably used.

1-50V is preferable and, as for the voltage applied in the electrolytic surface roughening using nitric acid type electrolyte solution, 5-30V is still more preferable. The current density (peak value) is preferably from 10 to 200 A / dm ^2, more preferably 20 to 150 A / dm ^2.

Quantity of electricity by summing all the processing steps, 100~2000C / dm ^2, preferably not 200~1500C / dm ^2, more preferably a 200~1000C / dm ^2.

  The temperature is preferably 10 to 50 ° C, more preferably 15 to 45 ° C. The concentration of nitric acid is preferably 0.1 to 5% by mass.

  If necessary, nitrates, chlorides, amines, aldehydes, phosphoric acid, chromic acid, boric acid, acetic acid, oxalic acid, and the like can be added to the electrolytic solution.

  In the present invention, the electrolytically roughened substrate is etched by immersing it in an alkaline aqueous solution in order to remove surface smut or the like or to control the pit shape.

  Examples of the alkaline aqueous solution include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium phosphate and the like.

  By performing the etching treatment with an alkaline aqueous solution, the printability and the background stain when the image forming layer of the present invention is provided are very good.

  After the immersion treatment with an alkaline aqueous solution, it is preferable to perform a neutralization treatment by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof. When the anodizing treatment is performed after the neutralizing treatment, it is particularly preferable that the acid used for the neutralization is matched with the acid used for the anodizing treatment.

  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 substrate by anodizing. In the present invention, the anodic oxidation treatment, an aqueous solution containing a concentration of 10-50% sulfuric acid and / or phosphoric acid or the like as an electrolytic solution, a method of electrolysis is preferably used at a current density of 1 to 10 A / dm ^2, the other In US Pat. No. 1,412,768, a method of electrolysis at high current density, a method of electrolysis using phosphoric acid described in US Pat. No. 3,511,661, etc. Can be used.

  The anodized base material may be subjected to a sealing treatment as necessary. These sealing treatments can be performed using known methods such as hot water treatment, boiling water treatment, water vapor treatment, dichromate aqueous solution treatment, nitrite treatment, ammonium acetate treatment.

  In addition, the anodized base material can be appropriately subjected to a surface treatment other than the sealing treatment. Examples of the surface treatment include known treatments such as silicate treatment, phosphate treatment, various organic acid treatments, PVPA treatment, and boehmite treatment. Further, an organic acid treatment such as citric acid may be performed following the treatment with an aqueous solution containing a bicarbonate described in JP-A-8-314157 or the treatment with an aqueous solution containing a bicarbonate.

  Examples of the plastic film as the substrate according to the present invention include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

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

[Hydrophilic layer]
A substrate having a hydrophilic surface can be obtained by a method of hydrophilizing the surface of the substrate as described above or a method of providing a hydrophilic layer on the substrate.

  When the hydrophilic layer is provided, the hydrophilic layer includes a hydrophilic material, and a metal oxide is preferably used as the hydrophilic material.

  The metal oxide preferably contains metal oxide particles.

  Examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols.

  The form of the metal oxide particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide particles having different average particle diameters can be used in combination. The surface of the particles may be surface treated.

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

  The hydrophilic layer that can be used in the present invention preferably contains porous metal oxide particles as a metal oxide.

  As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

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

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

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

  As a preferred embodiment of the present invention, the hydrophilic layer can contain a photothermal conversion agent described later.

  Examples of the photothermal conversion material include the following materials.

  General infrared absorbing dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, organic compounds such as phthalocyanine dyes and naphthalocyanine dyes , Azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-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.

  JP-A-11-240270, JP-A-11-265062, JP-A-2000-309174, JP-A-2002-49147, JP-A-2001-162965, JP-A-2002-144750, JP-A-2001-219667. The compounds described in (1) can also be preferably used.

(Image forming layer)
A preferred embodiment of the printing plate material used in the present invention includes an embodiment having an on-machine developable image forming layer on a hydrophilic surface substrate or a hydrophilic layer. The image forming layer preferably forms an image by heat generated by exposure with an infrared laser.

  As one of the preferable embodiments of the image forming layer of the present invention, an embodiment in which the image forming layer contains a hydrophobizing precursor can be mentioned.

  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 JP-A-2000-56449.

  In the present invention, it is preferable to use thermoplastic hydrophobic particles or microcapsules enclosing a hydrophobic substance as the hydrophobizing precursor. Examples of the thermoplastic fine particles include heat-fusible fine particles and heat-fusible fine particles described later.

  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, palm fatty acid amide. Alternatively, methylolated products of these fatty acid amides, methylene bisstellaramide, ethylene bisstellaramide, and the like can be added. Coumarone-indene resin, rosin-modified phenol resin, terpene-modified phenol resin, xylene resin, ketone resin, acrylic resin, ionomer, and copolymers of these resins can also be used.

  Among these, it is preferable to contain any of polyethylene, microcrystalline, fatty acid ester, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, high-sensitivity image formation can be performed. In addition, since these materials have lubricity, damage when a shearing force is applied to the surface of the printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

  The heat-meltable fine particles are preferably dispersible in water, and the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm. When the average particle size is smaller than 0.01 μm, when the coating liquid for the layer containing the heat-meltable fine particles is applied onto the porous hydrophilic layer described later, the heat-meltable fine particles are not removed from the pores of the hydrophilic layer. It becomes easy to enter inside or into the gaps between fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, which may cause scumming. When the average particle size of the heat-meltable fine particles is larger than 10 μm, the resolution is lowered.

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

  As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used. As content of the heat-meltable 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 polymer fine particles, but the temperature is the decomposition temperature of the polymer fine particles. Lower is preferred. 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 heat-fusible fine particles are preferably dispersible in water, and the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm. When the average particle size is smaller than 0.01 μm, when the coating liquid for the layer containing the heat-fusible fine particles is applied onto the porous hydrophilic layer described later, the heat-fusible fine particles It becomes easy to get into the pores or into the gaps between the fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, resulting in fear of soiling. When the average particle size of the heat-fusible fine particles is larger than 10 μm, the resolution is lowered.

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

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

[Other materials that can be contained in the image forming layer]
The image forming layer used in the present invention may further contain the following materials. The above-mentioned photothermal conversion material can be contained in the image forming layer. Since a part of the image forming layer is developed on-press, it is preferable to use a material that is less colored with visible light, and it is preferable to use a dye.

  The image forming layer can contain a water-soluble resin or a water-dispersible resin. Examples of water-soluble resins and water-dispersible resins include oligosaccharides, polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymers, and methyl methacrylate-butadiene copolymers. Examples thereof include resins such as conjugated diene polymer latex, acrylic polymer latex, vinyl polymer latex, polyacrylic acid, polyacrylate, polyacrylamide, and polyvinylpyrrolidone.

  Of these, oligosaccharides, polysaccharides, polyacrylic acid, polyacrylates (such as Na salts), and polyacrylamide are preferable.

  Examples of the oligosaccharide include raffinose, trehalose, maltose, galactose, sucrose, and lactose, and trehalose is particularly preferable.

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

  The polyacrylic acid, polyacrylic acid, polyacrylate (Na salt, etc.), and polyacrylamide preferably have a molecular weight of 3,000 to 5,000,000, and more preferably 5,000 to 1,000,000.

  The image forming layer can contain a water-soluble surfactant. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

  Further, it may contain an acid (phosphoric acid, acetic acid, etc.) or an alkali (sodium hydroxide, silicate, phosphate, etc.) for pH adjustment.

  In order to avoid the surface of the image-forming layer being rubbed before printing and scratches adhering to the hydrophilic surface from affecting the printed matter, the silica having an average particle diameter that can protrude beyond the film thickness of the image-forming layer It is preferable to add inorganic particles such as titanium oxide or organic resin particles such as acrylic and styrene. The average particle size of these particles is usually 0.2 to 10 μm, preferably 0.5 to 5 μm.

The amount per image forming layer, a 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.

  As a preferable aspect of the lithographic printing plate material according to the present invention, an image forming layer is provided on an aluminum substrate whose surface has been hydrophilized, or a hydrophilic layer provided on the substrate. Alternatively, a lithographic printing plate material containing a photothermal conversion agent can be listed as any of the constituent layers on the substrate.

  The constituent layer according to the present invention is a layer including at least a thermal image forming layer. Examples of layers other than the thermal image forming layer include a protective layer provided on the thermal image forming layer and an undercoat layer provided below.

  As described above, it is preferable that the layer containing the colorant is a heat-sensitive image forming layer.

As a material used for the protective layer, a water-soluble resin or a water-dispersible resin can be preferably used. Further, hydrophilic overcoat layers described in JP-A Nos. 2002-019318 and 2002-086948 can also be preferably used. The amount per the protective layer is 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.

  In the present invention, the protective layer may contain a colorant.

  In a preferred embodiment, the image forming layer is a layer that can be developed on a printing press.

  “Developable on a printing press” means that the image forming layer in the non-image area can be removed by dampening water and / or printing ink in lithographic printing after exposure.

  In order to be developable on a printing press, it can be obtained by including the above-mentioned heat-sensitive material, water-soluble resin, water-dispersible resin, and the like.

[Image heating]
As a method for imagewise heating according to the present invention, there is a method by heating with a medium such as a thermal head or irradiation with laser light as described above, but a method using laser light is preferred in the present invention. Among the methods using laser light, 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.

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

  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 particular, in an apparatus that performs exposure on a printing apparatus, the exposure method (3) is used.

[On-press development method]
In the planographic printing method according to the present invention, a part of the unexposed part due to image exposure is removed by the pre-development process, but is removed on the printing machine at the time of printing and printing is performed.

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

In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.
(1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several 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.

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

Next, this aluminum plate was subjected to electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was. The distance between the electrode and the sample surface at this time was 10 mm. Perform electrolytic graining treatment is divided into 12 times, and the quantity of electricity used in one treatment (at a positive polarity) as the 40C / dm ^2, treatment quantity of electricity 480C / dm ² in total (at a positive polarity). In addition, a rest period of 5 seconds was provided between each surface roughening treatment.

After the 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 1.2 g / m ^2. Etching, washing with water, and then dipping in a 10% aqueous sulfuric acid solution maintained at 25 ° C. for 10 seconds to neutralize, followed by washing with water. Next, anodization was performed in a 20% sulfuric acid aqueous solution so that the amount of electricity was 150 C / dm ² under a constant voltage condition of 20 V, followed by washing with water.

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

Next, a solution obtained by diluting pure water to a 0.1 mass% aqueous solution as SiO ₂ concentration of lithium silicate LSS-45 manufactured by Nissan Chemical Co., Ltd. was immersed in a bath heated to 50 ° C. for 30 seconds, then washed with water, Dry at 60 ° C. for 3 minutes.

  A material having the following composition was sufficiently stirred and mixed using a homogenizer and then filtered to prepare a hydrophilic layer coating solution having a solid content of 15% by mass.

On the roughened aluminum plate, a hydrophilic layer coating solution is applied using a wire bar so that the applied amount after drying is 2.5 g / m ² and dried at 110 ° C. for 3 minutes. And the base material 1 which has a hydrophilic layer was produced.

(Hydrophilic layer coating composition)
Hydrophilic layer colloidal silica (alkaline): Snowtex-S (Nissan Chemical Co., Ltd.)
(Solid content 30.0%) 3.33 parts Necklace-shaped colloidal silica (alkaline): Snowtex-PSM
(Nissan Chemical Co., Ltd.) (solid content 20.0%) 7.50 parts lithium silicate 35
(Nissan Chemical Co., Ltd., solid content 20.0% as amorphous silica) 3.00 parts Layered mineral particles Montmorillonite: Mineral colloid MO (manufactured by Southern Clay Products, average particle size 0.1 μm) was vigorously stirred with a homogenizer and 5 2.00 parts of low-magnetization amount black pigment: ETB-300 (manufactured by Titanium Industry Co., Ltd.) 4.79 parts of trisodium phosphate.12 water (reagent manufactured by Kanto Chemical Co., Inc.) 0% by weight aqueous solution
0.10 parts porous metal oxide particle SILTON AMT08
(Mizusawa Chemical Co., Ltd., porous aluminosilicate particles, average particle size 0.6 μm) 1.50 parts Porous metal oxide particles Shilton JC-30
(Mizusawa Chemical Co., Ltd., porous aluminosilicate particles, average particle size 3 μm) 0.50 parts Pure water 7.28 parts [Preparation of printing plate material]
Subsequently, materials having the following composition were sufficiently mixed and stirred, and filtered to prepare a coating solution for an image forming layer having a solid content of 10% by mass.

The hydrophilic layer coating solution is applied, and the image forming layer coating solution is applied onto the dried substrate 1 using a wire bar so that the dry weight is 0.7 g / m ² . Dry at 1 ° C. for 1 minute. Next, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material.

(Image forming layer coating solution composition)
Matt material Porous metal oxide particles Shilton JC-40
(Mizusawa Chemical Co., Ltd., porous aluminosilicate particles, average particle size 4 μm) 10.0 parts Lubricant Amide wax emulsion: Nissan Electol WEP-5 (Nippon Yushi Co., Ltd., solid content 40% by mass) 25.0 parts Carnauba wax emulsion: A118
(Gifu Shellac, average particle size 0.3 μm, melting point 80 ° C., solid content 40% by mass)
170 parts Sodium polyacrylate: Aqualic DL522
100 parts by mass of an aqueous solution (manufactured by Nippon Shokubai Co., Ltd.), solid content: 10 parts by weight Photothermal conversion dye: ADS830WS
1 mass% aqueous solution (made by American Dye Source) 2.00 parts pure water 1893 parts (exposure with infrared laser)
The lithographic printing plate material was wound around an exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm was used for exposure, and an image was formed with 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines. The exposed image is a solid image, a 1 to 99% halftone dot image, a 2400 dpi line and space thin line image, registration marks for confirming positions at the four corners of the printing plate (both are printable areas), and upper and lower portions of the printing plate. A mark indicating the distinction is included in the holding portion and the holding bottom portion that do not cover the print area. A solid round mark with a diameter of 2 cm was recorded on the mouth part, and a solid square mark with a side of 1.5 cm was recorded on the bottom part of the mouth.

(Processing before printing)
Using the cellulose sponge made by Toray Fine Chemical Co., Ltd. with water added to the holding part and the holding bottom part of the exposed lithographic printing plate material before printing, the surface of the image forming layer is rubbed, and the image forming layer is exposed from the surface. Was removed. While the rubbed area can retain water, the circle for distinguishing the upper and lower sides and the square mark part repels water, so that the upper and lower sides can be easily distinguished. If this processing is not performed, it is difficult to see the upper and lower discrimination circles and square marks.

Printing method Image exposure is performed on each printing plate of K (black), C (cyan), M (magenta), and Y (yellow), and then OK Topcoat (Oji Paper Co., Ltd.) is used with a Lislon 426 printing machine manufactured by Komori Corporation. Co., Ltd.), fountain solution: ASTROMARK 3 (Niken Chemical Research Laboratories) 2% by mass, ink (TK High Unity Neo ink, indigo, red, yellow) manufactured by Toyo Ink Co., Ltd. 9000 sheets / hour Printing was performed at a printing speed of. The printing order was K → C → M → Y.

  The exposed lithographic printing plate material was directly attached to the plate cylinder of a printing press, and printing was performed up to 20000 sheets using the same printing conditions and printing sequence as the PS plate.

(Comparative example)
About the said invention example, it printed in the same way except having changed so that "the process before printing may not be performed."

"Evaluation methods"
[Frame dirt]
Both ends of the printed material were observed from the start of printing, and the number of sheets on which the ink stain (frame stain) of the printed material hitting the edge of the printing plate could not be visually confirmed was confirmed. In the case of the comparative example, up to 100 sheets, streaks of printing ink were adhered to both ends, whereas in the case of the present invention, only the printing ink was adhered.

[Misplacement]
The amount of misregistration of the M registration marks with respect to K of the 100th printed material and the 20000th printed material was measured. The number of printed sheets when the registration mark deviation amount exceeded 20 μm was confirmed.

  In the case of the present invention, the misalignment amount of the registration marks was 20 μm or less even after printing 20000 sheets, whereas in the case of the comparative example, 5000 sheets exceeded 20 μm.

Claims (5)

In the processing method of a lithographic printing plate material having an image forming layer in which at least an imagewise exposed region by imagewise heating or light energy cannot be removed in a printing process of a printing machine on a substrate having a hydrophilic surface, A processing method for a lithographic printing plate material, comprising removing the image forming layer in a partial region around the lithographic printing plate material before the step of attaching the lithographic printing plate material to a printing machine and performing printing. 2. The method for processing a lithographic printing plate material according to claim 1, wherein the region from which the image forming layer is removed is a non-printing region. The method for processing a lithographic printing plate material according to claim 1 or 2, wherein the region from which the image forming layer is removed is a holding portion or a holding bottom portion of the lithographic printing plate material when attached to a printing press. The method for processing a lithographic printing plate material according to any one of claims 1 to 3, wherein an image is recorded imagewise by heat or light energy in a region from which the image forming layer is removed. A lithographic printing plate, which is processed by the method for processing a lithographic printing plate material according to any one of claims 1 to 4.