JP5166712B2 - Planographic printing plate precursor - Google Patents

Description

  The present invention is a lithographic printing plate that can be used for lithographic printing, which can obtain an image having high resolution, is excellent in handleability in a bright room, does not require a processing solution, and has a low production cost. Regarding the original edition.

  With the recent development of computers and peripheral devices, a planographic printing plate making method using various digital printers has been proposed. Such a lithographic printing plate making method involves making a plate using a dry electrophotographic laser printer due to the difference in the method of forming the image portion (Japanese Patent Laid-Open Nos. 6-138719, 6-250424, and 6). 7-1847, etc.), plate making using an on-demand ink jet printer using hot-melt ink (Japanese Patent Laid-Open No. 9-58144), and printing an oleophilic material or an image fixing material using an ink jet printer. Plate making (JP-A-56-105960, JP-A-8-295683, etc.), plate-making with a thermal printer using a thermal transfer ink ribbon (JP-A 63-166590), thermal laser Or plate making with a thermal printer without using an ink ribbon (Japanese Patent No. 3522450) Broadcast), and the like.

  Unlike the conventional plate making method of a lithographic printing plate using a photosensitive layer or a photosensitive resin using a silver halide emulsion, the plate making method by the above various digital printers is not restricted by safety light in handling, and after image recording. There is an advantage that a lithographic printing plate can be easily and easily made in that no development treatment with an aqueous developer is required.

  Among plate making methods using the above-mentioned various digital printers, the plate making method using an ink jet printer is expected to become a high quality and low cost plate making method because it can print with higher definition than other methods due to the recent development of ink jet printers. it can. In the plate making method using these ink jet printers, for example, as described in International Publications WO / 0037261 pamphlet and WO / 0037254 pamphlet, an oleophilic substance is imaged on a lithographic printing plate precursor having a hydrophilic surface. Making a plate by printing on. However, the ink composition containing the aqueous oligomer dispersion in WO / 0037261 pamphlet and the ink composition containing the aqueous emulsion of organic film-forming polymer in WO / 0037254 pamphlet When an ink composition in which a lipophilic substance is dispersed or dissolved in a solvent is used, there is a problem that the ink composition dries during printing or after printing, and the head of the ink jet printer is packed.

  On the other hand, in the plate making method of an ink jet printer using an ultraviolet curable resin as an ink composition proposed in, for example, Japanese Patent Laid-Open No. 56-105960 (Patent Document 1), a solid material that fills the head of the ink jet printer is contained. The above problem is very unlikely to occur. However, due to the property that the ultraviolet curable resin is a liquid until it is irradiated with ultraviolet rays, if the ultraviolet rays are not irradiated immediately after printing, bleeding occurs in the image and the image quality is deteriorated. In order to solve this problem, as proposed in Japanese Patent Application Laid-Open No. 2004-322560, for example, an ultraviolet lamp is usually placed next to the printer head. A mechanism that suppresses the heat generated by the lamp is required, and a head with a very special structure is required. Accordingly, there has been a demand for the development of a system that does not cause blurring of images without using such a special head.

  In order to solve the above problem, a method of suppressing bleeding by providing an ink receiving layer on a lithographic printing plate precursor has been proposed. For example, in JP-A-2005-144692 (Patent Document 2), 3 to 50% by mass of the ink composition is a non-ultraviolet curable organic solvent in a lithographic printing plate precursor having a porous hydrophilic layer having a pore diameter of 10 to 50 nm. And a method for printing an ink composition containing an ultraviolet curable resin has been proposed. Alternatively, Japanese Patent Application Laid-Open No. 5-204138 (Patent Document 3) proposes a method of printing an ink composition containing an ultraviolet curable resin on a lithographic printing plate precursor having an ink image-receiving layer made of a linear organic polymer. When a porous hydrophilic layer is provided on the surface of a lithographic printing plate precursor as in Patent Document 2 described above, absorption of the ink composition is accelerated, which is an effective means for preventing bleeding. However, this method has a problem that the printing durability of the highlight portion is weak. In addition, a porous hydrophilic layer composed of a small amount of a hydrophilic binder and a large amount of an inorganic pigment as described in Patent Document 2 generally has low strength, and has a problem of peeling during printing and causing stains. . On the other hand, when the image receiving layer is composed of a hydrophilic polymer as in Patent Document 3, the ink composition has a slow absorption rate and the problem of bleeding cannot be solved sufficiently.

  In the plate making method using an ink jet printer but not using an ultraviolet curable resin as an ink composition, there are problems of preventing bleeding and ensuring stain resistance as in the plate making method using an ultraviolet curable resin as an ink composition. Various solutions have been proposed. However, as described in, for example, JP-A-2004-66816 and JP-A-10-119230, the lipophilic substance in the ink composition and the charge on the lithographic printing plate precursor surface are reversed to electrically The ink composition is solidified at the stage where the ink composition is printed on the lithographic printing plate as in the hot melt type ink jet described in JP-A-10-315645. There are known techniques for preventing bleeding. However, the problem of using an ultraviolet curable resin that remains liquid after printing as an ink composition cannot be solved.

Applying an easy-adhesion layer containing a polymer latex on a film such as a polyester film is widely performed, and many patents have been filed. For example, in JP 2000-229396 A (Patent Document 4), an easy-adhesion layer containing a self-emulsifiable isocyanate compound having two or more isocyanate groups and a hydrophobic latex is coated on a polyester film to improve adhesion. Proposed method to do. The quality required for these easy-adhesion layers is sufficient adhesion when an easy-adhesion layer is applied and dried, and then an aqueous coating solution containing various water-soluble polymers as a binder is applied thereon, or The purpose is to prevent blocking between films after the easy adhesion layer is applied and wound.
JP 56-105960 A (first page) Japanese Patent Laying-Open No. 2005-144692 (first page) Japanese Patent Laid-Open No. 5-204138 (first page) JP 2000-229396 A (page 4)

  An object of the present invention is to provide a lithographic plate capable of obtaining an image having high resolution, having excellent handleability in a bright room, requiring no processing liquid, and having high printing durability and stain resistance in printing. The purpose is to provide a printing plate precursor.

The above object of the present invention has been achieved by the following invention as a result of intensive studies.
1) In a lithographic printing plate precursor for printing and printing an ink composition containing an ultraviolet curable resin by an inkjet method, an undercoat layer containing a water-soluble polymer and a polymer latex having a Tg of 20 ° C. or less on a support; A lithographic printing plate precursor further comprising a porous hydrophilic layer as an upper layer.
2) The lithographic printing plate precursor as described in 1 above, wherein the mass ratio of the polymer latex content to the water-soluble polymer content in the undercoat layer is 1 to 30.
3) The above-mentioned 1 characterized in that the undercoat layer further contains at least one hardener selected from aldehyde hardeners, hardeners containing methylol groups, and active vinyl hardeners. Or the planographic printing plate precursor described in 2 above.

  According to the present invention, it is possible to obtain an image having high resolution, excellent handling properties in a bright room, no processing liquid is required, and high printing durability and stain resistance in printing. It is possible to provide a printing plate precursor.

  In the present invention, an undercoat layer is provided on the support of the lithographic printing plate precursor in order to ensure excellent printing durability and stain resistance. The undercoat layer contains a water-soluble polymer and a polymer latex having a Tg of 20 ° C. or lower.

  In the present invention, the Tg of the polymer latex used for the undercoat layer is 20 ° C. or less, preferably 10 ° C. or less. As the polymer latex used in the present invention, various known latexes such as homopolymers and copolymers can be used as long as Tg is 20 ° C. or lower. Homopolymers include butyl acrylate, butadiene, and isoprene, and copolymers include ethylene / butadiene copolymers, styrene / butadiene copolymers, methyl methacrylate / butadiene copolymers, and methyl methacrylate / vinylidene chloride copolymers. , Methyl acrylate / acrylonitrile copolymer, methyl acrylate / butadiene copolymer, methyl acrylate / styrene copolymer, methyl acrylate / vinyl acetate copolymer, acrylic acid / butyl acrylate copolymer, methyl acrylate / vinyl chloride copolymer And butyl acrylate / styrene copolymer. Among these, anionic polymer latex is preferable, and it is preferable to use a polymer latex containing a carboxyl group. Examples of the polymer latex containing a carboxyl group include carboxyl-modified styrene / butadiene latex and carboxyl-modified acrylonitrile / butadiene latex. The average particle size of the polymer latex used in the present invention is preferably 0.01 to 1.0 μm, more preferably 0.05 to 0.8 μm.

  In the present invention, various known hydrophilic polymers can be used as the water-soluble polymer contained in the undercoat layer. Specific examples thereof are described in kappa type, iota type, lambda type carrageenan, fucoidan, porphyran, chondroitin sulfate, dermatan sulfate, keratan, hyaluronic sulfate, dextran sulfate, polyvinyl sulfate, and Japanese Patent Application Laid-Open No. 2005-120068. Sulfated chitosan or sodium salt, potassium salt, rubidium salt, etc. of these water-soluble polymers, and starches, seaweed mannan, agar, sodium alginate, mannan, pectin, tragacanth gum, caraya gum, xanthine gum, guar bin gum, roast bin gum, Arabia Homopolysaccharides such as gum, dextran, glucan, xanthan gum and levan, microbial mucilage such as heteropolysaccharide such as succinoglucan, pullulan, curdlan and xanthan gum, glue, gelatin , Proteins such as casein and collagen, chitin derivatives. Cellulose derivatives, modified gums such as carboxymethyl guar gum, baked starches such as dextrin, processed starches such as oxidized starches, esterified starches, etc., polyvinyl alcohol, partially acetalized polyvinyl alcohol, allyl modified polyvinyl alcohol, polyvinylmethyl Polyacrylic acid derivatives such as ether, polyvinyl ethyl ether, polyvinyl isobutyl ether, polyacrylic acid salt, polyacrylic acid ester partial saponified product, polymethacrylic acid salt, polyacrylic acid amide, polymethacrylic acid derivative, polyethylene Glycol, polyethylene oxide, polyvinylpyrrolidone, vinylpyrrolidone / vinyl acetate copolymer, carboxyvinyl polymer, styrene / maleic acid copolymer, styrene / croto Acid copolymer and the like. Of these, a water-soluble polymer having a hydroxyl group and a sulfate thereof is preferable, and carrageenans are preferably used because they have setability and are easy to apply. The molecular weight of the preferred water-soluble polymer is not particularly defined, but is preferably 50000 or more, more preferably 80000 or more. These water-soluble polymers may be used alone or in combination.

In the present invention, the mass ratio of the polymer latex content to the water-soluble polymer content contained in the undercoat layer is 1 to 30, preferably 3/2 to 20, and more preferably 2 to 10. If the ratio of the polymer latex is small, printing durability cannot be obtained, and if it is too large, stains occur during printing. A preferred use amount of the polymer latex is 0.5 to 5 g / m ² , more preferably 1 to 3 g / m ² . The preferred amount of the water-soluble polymer is 0.05-5 g / m ^2, more preferably from 0.1 to 3 g / m ^2.

  In the present invention, the undercoat layer is preferably cross-linked using a cross-linking agent that can cross-link with the water-soluble polymer used in the undercoat layer so that the undercoat layer cannot be removed during printing. Examples of the cross-linking agent include inorganic compounds such as chromium alum, aldehydes such as formalin, glyoxal, malealdehyde, and glutaraldehyde, N-methylol urea, N-methylol melamine, N-methylol ethylene urea, and early stages thereof. N-methylol compounds such as condensates, mucochloric acid, aldehyde equivalents such as 2,3-dihydroxy-1,4-dioxane, 2,4-dichloro-6-hydroxy-S-triazine salts, 2,4 -Compounds having active halogen such as dihydroxy-6-chloro-S-triazine salt, activated vinyl compounds such as bis (vinylsulfonyl) methane, bis (vinylsulfonylmethyl) ether, N, N, N-triacryloyl Hexahydrotriazine, an active three-membered ethyleneimino group Use one or more of various compounds such as compounds having two or more poxy groups in the molecule, compounds having two or more isocyanate groups in the molecule, and dialdehyde starch as a polymer hardener. Can do. In addition to these, known cross-linking agents such as the cross-linking agents described in “Chemical Reaction of Polymer” (Nobu Okawara, 1972, Chemical Dojinsha), etc. Can be used. Among these crosslinking agents, it is preferable to use an aldehyde-based crosslinking agent, a crosslinking agent containing a methylol group, or an active vinyl crosslinking agent since printing durability is improved. The usage-amount of a crosslinking agent is 1-20 mass% with respect to water-soluble polymer, Preferably it is 5-10 mass%.

  In the present invention, in addition to a water-soluble polymer, a polymer latex having a Tg of 20 ° C. or less, and a crosslinking agent, various matting agents, antistatic agents, surfactants, pigments, coloring agents such as pigments, and the like are added to the undercoat layer. You can also.

  In the present invention, the undercoat layer containing a water-soluble polymer and a polymer latex having a Tg of 20 ° C. or lower has at least one porous hydrophilic layer, and the porous hydrophilic layer is an ink composition. It is preferable to exist as the outermost layer in order to absorb water. In the present invention, the porous hydrophilic layer means a layer having an average pore diameter of at least 50 nm or more, preferably 100 to 200 nm, and a pore volume of 50 nm or more being 0.1 mL / g or more. . In order to provide such a porous hydrophilic layer, a layer containing an inorganic pigment and a water-soluble polymer and having a ratio of 1/1 (inorganic pigment / water-soluble polymer) or more is applied. The details will be described later. The average pore size and the volume of the porous hydrophilic layer can be measured using a gas adsorption method (for example, SA3100 manufactured by Beckman Cole Counter Co., Ltd.).

  Hereinafter, details of the porous hydrophilic layer used in the present invention will be described. As the water-soluble polymer that can be used in the porous hydrophilic layer in the present invention, the same water-soluble polymer as that of the undercoat layer described above can be used, and preferably a water-soluble polymer having a hydroxyl group and a sulfate thereof. Molecules are preferred. It is particularly preferable to use carrageenans.

  The porous hydrophilic layer of the lithographic printing plate precursor according to the invention contains an inorganic pigment together with a water-soluble polymer. As the inorganic pigment, various known inorganic pigment particles such as silica, zinc oxide, titanium oxide, alumina, zirconia, tin oxide, magnesium oxide, antimony oxide, cerium oxide, niobium oxide, barium sulfate, calcium carbonate, and clay can be used. However, it is most preferable to use silica particles. Further, any of the above inorganic pigments can be used in combination.

  In the present invention, the porous hydrophilic layer is provided by applying and drying a coating liquid. Therefore, the inorganic pigment used in the present invention is preferably used in the form of a slurry and mixed with the coating liquid. . The production process of the inorganic pigment particle slurry of the present invention includes a primary dispersion process in which inorganic pigment particles are added to a dispersion medium and mixed (preliminary mixing), and a coarse dispersion obtained in the primary dispersion process is dispersed in a dispersing device (for example, a high-pressure homogenizer). Or a ball mill).

  The preliminary mixing in the primary dispersion step can be performed by ordinary propeller stirring, turbine stirring, homomixer stirring, ultrasonic stirring, or the like. As a dispersion apparatus used in the secondary dispersion step, at least one selected from a high-pressure homogenizer, an ultra-high pressure homogenizer, an ultrasonic disperser, and a thin film-circulating disperser is preferably used. The high-pressure homogenizer is a dispersion machine that uses shearing force when passing the workpiece through the gap between the valve and the valve seat at high pressure and high speed, and is widely known as a gourin type. APV Gourin, Runny, NIRO SOAVI Commercially available from the company, Nippon Seiki Seisakusho, Sanwa Kikai Co., Ltd., and the like. The ultra-high pressure homogenizer is a disperser capable of processing at higher pressures that cannot be achieved with a high-pressure homogenizer, and uses the shearing force and impact force when passing the object to be processed through the narrow and narrow path in the chamber at high pressure and high speed. Sugino Machine Co., Ltd. is known, as well as the opposed collision type jet pulverization type that uses shearing force when the liquids to be treated are jetted at high pressure and high speed from the opposed nozzles to collide with the liquids to be treated. Commercially available products such as Optimizer, Microfluidizer, Nanomizer from Mizuho Industry Co., Ltd., Nanomizer, etc. can be used. The ultrasonic disperser is a disperser using ultrasonic vibration energy generated from an ultrasonic oscillator, and commercially available from Nippon Seiki Seisakusho Co., Ltd. can be used. A thin-film disperser is a type that uses shear stress when a liquid to be treated is introduced into a chamber with a brush and has a high-speed rotation shaft, and the liquid to be treated becomes a thin film and moves up the inner wall of the chamber. Yes, it is possible to use a product marketed under the trade name “Filmix” from Tokushu Kika Kogyo Co., Ltd.

  The inorganic pigment dispersion medium is mainly composed of water, but may contain a small amount of an organic solvent (a lower alcohol such as ethanol or a low boiling point solvent such as ethyl acetate). In that case, the organic solvent is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total dispersion medium. Various known pH buffering agents such as sodium acetate, borax and sodium hydrogen carbonate can also be added. In addition, a water-soluble polymer can be used as a dispersion aid.

  The particle shape of the inorganic pigment used in the present invention can be any shape such as a sphere, needle shape, feather shape, or irregular shape, and these particles can be used as primary particles to take the form of aggregated secondary particles. You can also. Among these, the shape of the inorganic pigment particles used in the present invention is preferably secondary particles in which primary particles are aggregated in a lump, and the average primary particle diameter is particles of 25 nm or less, and this is agglomerated in a lump. It is preferable to form secondary particles. Such silica includes synthetic silica fine particles (hereinafter referred to as vapor-phase process silica) produced by a vapor phase method disclosed in JP-B-3-56552, JP-A-10-81064 and the like. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd., and as QS type from Tokuyama Co., Ltd., and can be obtained.

  The secondary average particle diameter of the preferable inorganic pigment particles in the present invention is preferably 1 μm or less, more preferably 500 nm or less. By using such fine particles, a layer having a preferable porous structure can be formed. In the present invention, the average particle diameter of the inorganic pigment particles is the average particle diameter of the secondary particles when the pigment forms secondary particles, and the average particle diameter of the primary particles when the pigment is not formed. Means. The average particle diameter of secondary particles having an average particle diameter of 50 nm or more, or primary particles in the case where secondary particles are not formed and having an average particle diameter of 50 nm or more is also determined by a laser scattering type particle size distribution meter (for example, It can be measured by HORIBA, Ltd., LA920). Smaller particles can be confirmed using an electron microscope. Further, when the particles form secondary particles in which the primary particles are aggregated, the size of the primary particles and the shape of the aggregation can be confirmed using the same electron microscope.

In the present invention, the ratio of the inorganic pigment / water-soluble polymer of the porous hydrophilic layer is 1/1 or more, more preferably 3/2 to 10/1. With such a ratio, it is possible to take a porous structure in which pores of 50 nm or more are opened and the volume in the pore layer is 0.1 mL / g or more. Although the influence on the printability due to the thickness of the porous hydrophilic layer is reduced by providing an undercoat layer in the present invention, the thickness of the porous hydrophilic layer is very important in the present invention. The ink will not be applied, and if it is too thin, a bleeding problem will occur. Therefore, the coating amount of the porous hydrophilic layer in the present invention is 0.06~5g / m ² in terms of solid content, preferably 0.1 to 3 g / m ^2, more preferably is 0.2 to 2 g / m ² . The amount of the inorganic pigment of the porous hydrophilic layer is 0.05-5 g / m ^2, preferably 0.1-2 g / m ^2. The same amount of the water-soluble polymer 0.025~3g / m ^2, preferably from 0.05 to 0.5 g / m ^2.

In the present invention, the porous hydrophilic layer has a multilayer structure, and a higher printing durability can be obtained by increasing the inorganic pigment / water-soluble polymer ratio of the hydrophilic layer on the surface than the porous hydrophilic layer closer to the support. More preferably. Preferred coating weight of the surface side of the hydrophilic layer is 0.5 g / m ² or less in terms of solid content, more preferably from 0.01~0.4g / m ^2, be 0.05 to 0.3 g / m ² Is more preferable. Among them, the preferred amount of the inorganic pigment as the main component is 0.02 to 0.4 g / m ² , more preferably 0.06 to 0.25 g / m ² . The amount of the water-soluble polymer is preferably 0.001 to 0.1 g / m ^2, more preferably a 0.002~0.05g / m ^2.

  In the present invention, it is preferable to crosslink using a crosslinking agent capable of crosslinking reaction with the water-soluble polymer used in the porous hydrophilic layer so that the porous hydrophilic layer cannot be removed during printing. As the cross-linking agent, the same cross-linking agent as in the above-mentioned undercoat layer can be used, but among these cross-linking agents, aldehydes are preferably used. The usage-amount of a crosslinking agent is 1-20 mass% with respect to water-soluble polymer, Preferably it is 5-10 mass%.

  In order to coat the porous hydrophilic layer of the lithographic printing plate precursor according to the present invention, an anionic, cationic or nonionic surfactant may be used as an auxiliary agent. In particular, for a porous hydrophilic layer present on the surface, it is preferable to use a fluorine-containing surfactant or a silicon-containing surfactant in order to prevent image bleeding.

  In addition, the porous hydrophilic layer of the lithographic printing plate precursor according to the present invention may use a matting agent, a thickener, an antistatic agent, and the like. Further, coloring materials such as pigments such as carbon black and phthalocyanine blue and dyes such as food blue No. 1, No. 2 and food red No. 3 can be added.

  In the present invention, it is preferable to apply the porous hydrophilic layer and the undercoat layer simultaneously in order to reduce the number of steps.

  In the present invention, the support of the lithographic printing plate precursor can be any water-resistant support, such as resin-coated paper, synthetic paper, polyester resin such as polyethylene terephthalate, diacetate resin, triacetate resin, acrylic resin. A synthetic or semi-synthetic polymer film such as polycarbonate resin, polyvinyl chloride, polyimide resin, cellophane or celluloid, a metal plate such as aluminum or iron, or the like can be used. Among them, it is preferable to use a base of polyester resin such as resin-coated paper or polyethylene terephthalate. In addition, the surface of these supports can be subjected to a surface treatment such as a corona treatment in order to improve adhesion with a layer to be coated as an upper layer.

  In the present invention, the lithographic printing plate precursor includes a porous hydrophilic layer and an undercoat layer, as well as a conductive layer, an antistatic layer, an anti-curl layer for preventing curling of the support, and a curl acceleration for imparting a desired curl. Layers and the like can be provided.

  In the present invention, the lithographic printing plate precursor is made by imagewise printing an ink composition containing an ultraviolet curable resin with an inkjet printer, and then irradiating the printed lithographic printing plate with ultraviolet rays over the entire surface.

  The ink composition used in the present invention contains an ultraviolet curable resin, a polymerization initiator, and a diluent, and may further contain a coloring material, a surfactant, and an auxiliary agent.

  As the ultraviolet curable resin used in the ink composition used in the present invention, various known ultraviolet curable resins such as urethane acrylate type, epoxy acrylate type, and polyester acrylate type can be used. Further, among these ultraviolet curable resins, it is preferable to use an aqueous ultraviolet curable resin in order to use a diluent that is less harmful to the human body. Examples of such water-based ultraviolet curable resins include JP-A-3-168209, JP-A-4-21413, JP-A-5-140251, JP-A-7-242716, JP-A-7-25958, JP-A-7-62026, JP-A-6-287260, JP-A-9-146270, JP-A-5-222135, JP-A-9-136981, JP-A-6-298851, JP-A-6-29885 There are ultraviolet curable resins described in JP-A-7-43900. Particularly preferred UV curable resins are those having a Log P in the range of 0 to 4, and UV curable resins having three or more reactive groups such as acryloyl groups and methacryloyl groups in the molecule are also obtained after curing. Is preferable because an image having high printing durability and high printing durability can be easily obtained. In the present invention, LogP means an n-octanol / water partition coefficient, and was calculated based on the Crippen method described in “J. Chem. Inf. Compt. Sci., 27, 21 (1987)”. The predicted value of LogP is used. In addition, water-based curable resins are roughly classified into water-soluble UV curable resins, forced emulsification type UV curable resins, and self-emulsifying type UV curable resins. Thereafter, it is difficult to redissolve in the diluent and the head may be clogged. It is preferable to use a water-soluble cured resin. However, even with self-emulsifying type UV curable resins, the disadvantages can be eliminated by dissolving them once using a water-soluble organic solvent such as ethyl alcohol, or a water-soluble UV curable resin or a polymerization initiator as a solvent. It is also preferable to dissolve and use a self-emulsifying ultraviolet curable resin that forms a strong film after irradiation.

  The ultraviolet curable resin in the ink composition used in the present invention can be used alone or in combination of two or more. Moreover, the density | concentration of the total ultraviolet curable resin in an ink composition is 1-40 mass%, More preferably, it is 5-30 mass%.

  The ink composition used in the present invention contains a photopolymerization initiator. When high-energy rays such as electron beams are used as active energy rays instead of ultraviolet rays, it is possible to create an image with sufficient strength to be printed without a photopolymerization initiator, but it is safe and simple. It is preferable to use ultraviolet rays. Therefore, the ink composition used in the present invention contains a photopolymerization initiator and is irradiated with ultraviolet rays after printing to fix the image.

  As a photopolymerization initiator, it is soluble in water, the surface tension adjusting agent used in the present invention, a water-soluble organic solvent, is stably present in ink, and radicals generated by ultraviolet rays are unsaturated double bonds and efficiency. Any one can be used as long as it reacts automatically. Specifically, benzoin compounds such as benzoin ethyl ether and benzoin isopropyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy- Examples thereof include acetophenone compounds such as 2-propyl) ketone, benzophenone compounds such as benzophenone, and thioxanthone compounds, but are not limited thereto, and two or more kinds may be used in combination. The usage-amount of these photoinitiators shall be 0.1-20 mass% with respect to ultraviolet curable resin. Photopolymerization initiation assistants such as triethanolamine and methyldiethanolamine can also be used.

  In the ink composition used in the present invention, a diluent is used to adjust the viscosity. In an ink jet printer, particularly an aqueous ink jet printer, the head is clogged with an ink composition having a high viscosity. Therefore, the viscosity is preferably 15 mPa · s or less, more preferably 10 mPa · s or less, and further preferably 2 to 5 mPa · s. In order to obtain such a preferable viscosity, a diluent is used because it is impossible with only an ultraviolet curable resin or a polymerization initiator. As the diluent, water is most preferable from the viewpoint of the environment, but when water alone cannot completely dissolve the ultraviolet curable resin, it is preferable to use ethanol. Furthermore, other known water-soluble organic solvents can also be used. Specific examples thereof include glycols such as ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, glycol ethers such as ethylene glycol monophenyl ether, N- Examples include pyrrolidones such as methyl-2-pyrrolidone, alkanolamines such as triethanolamine, alcohols such as methanol and isopropyl alcohol, and dimethyl sulfoxide. If the solvent remains at the time of ultraviolet exposure, the image strength is lowered. Therefore, it is preferable to use an organic solvent having a boiling point of 100 ° C. or lower. As a usage-amount of a diluent, water is 0-50 mass%, Preferably it is 2-20 mass%, and 30-90 mass% is preferable with a diluent in combination with another organic solvent.

  The ink composition used in the present invention preferably contains a color material for plate inspection after printing. As the coloring material, dyes and pigments generally used in ink jet recording inks can be used. Examples of the dye include azo dyes as direct dyes, phthalocyanine dyes, azo dyes as acidic dyes, and anthraquinone dyes. As the pigment, all conventionally known organic pigments and inorganic pigments can be used. Specific examples include organic pigments such as azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, isoindoline pigments, and inorganic pigments such as titanium oxide and carbon black, but are not limited thereto.

  These color materials can be used alone or in combination. The content of the color material in the ink composition is preferably in the range of 0.1 to 10% by mass in order to obtain good film strength and colorability.

  The ink composition used in the present invention may contain a surfactant as a surface tension adjusting agent. As the surfactant, silicone-based, fluorine-based, acrylic-based, and acetylenic diol-based surfactants generally used in water-based paints and inks can be used.

  In addition, the ink composition used in the present invention may contain auxiliary agents contained in known ink compositions. As auxiliary agents, alkali metal hydroxides, pH adjusters such as alkanolamines, antibacterial and antifungal agents, sequestering agents, pigment dispersants, water-soluble resins and the like may be used.

  In the present invention, after printing with an ink jet printer, the image is irradiated with ultraviolet rays to cure the image. The ultraviolet irradiation may be performed during printing or after printing. For example, as described in JP-A No. 2004-322560, an ultraviolet lamp may be provided right next to the inkjet head, or as described in JP-A No. 2000-186243. As described above, an ultraviolet lamp may be attached to the exit portion of the ink jet printer, or a known ultraviolet irradiation device independent of the printer may be used. However, use of an ultraviolet irradiation device that is independent of the printer to prevent the ink attached to the inkjet head from being cured by stray light because the intensity of the image is stronger when the diluent is evaporated and the ultraviolet rays are irradiated. Is preferred. Therefore, it is preferable that the time from the printing to the irradiation with ultraviolet rays is preferably between several seconds and several minutes. In addition, after printing, the lithographic printing plate precursor can be passed through a dryer before irradiation with ultraviolet rays to accelerate the drying of the diluent. However, when the temperature is applied, the viscosity of the ultraviolet curable resin decreases, and the resin moves. Preferably, it is dried by applying a wind of 50 ° C. or lower.

  As the ultraviolet lamp used in the ultraviolet irradiation apparatus, a so-called low-pressure mercury lamp whose mercury vapor pressure is 1 to 10 Pa during lighting, a high-pressure mercury lamp having a higher pressure, a mercury lamp coated with a phosphor, or the like Is preferred. The emission spectrum of these mercury lamps in the ultraviolet region is in the range of 184 nm to 450 nm, which is suitable for efficiently reacting the ultraviolet polymerizable compound in the black or colored ink. Moreover, since a small power supply can be used, it is suitable also in that sense. Examples of mercury lamps include metal halide lamps, high pressure mercury lamps, and ultra high pressure mercury lamps. In addition, xenon flash lamps, deep UV lamps, UV lasers, etc. have been put into practical use and the emission wavelength range includes the above range, so it should be selected and used as appropriate according to the power source size, input intensity, lamp shape, etc. Can do. The light source is preferably selected in consideration of the absorption wavelength of the photopolymerization initiator used.

The necessary ultraviolet intensity is preferably about ² to 50 mW / cm ^{2 in the} total energy of the ultraviolet part in order to obtain a better heavy speed. Since the desired printing durability cannot be obtained if the integrated irradiation amount is insufficient, it is preferable to perform the irradiation process in consideration of the necessary integrated irradiation amount.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but it is needless to say that the present invention is not limited by this description.

<Preparation of silica dispersion>
Aerosil 300 (vapor phase silica produced by Nippon Aerosil Co., Ltd.) (1.44 kg) was added to an aqueous solution containing 14.4 g of sodium hydroxide and 6.12 g of sodium acetate to make a total amount of 8 kg. This was stirred with a sawtooth blade type disperser at a blade peripheral speed of 30 m / sec for 90 minutes to obtain an 18% by mass silica coarse dispersion. The silica coarse dispersion obtained in the primary dispersion step was emulsified and dispersed three times with a high-pressure homogenizer under conditions of a treatment amount of 40 L / hour and a pressure of 19614 kPa to obtain a silica dispersion. The obtained dispersion was stored at 60 ° C. for 1 hour with a propeller blade-type disperser while stirring at low speed to obtain a silica slurry. When the particle diameter in the obtained slurry was examined using a laser scattering particle size distribution analyzer HORIBA LA920, the secondary particle diameter was 0.1 μm. Further, when observed with an electron microscope, it was an aggregate in which primary particles having a primary particle diameter of 12 nm were aggregated in a lump.

After corona discharge processing of double-sided polyethylene-coated paper (RC paper) having a basis weight of 135 g / m ² , an undercoat layer is applied according to the formulation shown below, and the support-side porous material containing the above-described silica slurry thereon. A hydrophilic layer and a surface-side porous hydrophilic layer were applied in this order according to the following formulation. As a result of measuring the pore size distribution of the obtained sample using a specific surface area measuring device SA3100 (manufactured by Beckman Cole Counter Co., Ltd.), pores of 50 to 200 nm were observed, and the capacity was 0.38 mL. / G.

(Undercoat layer formulation A / 1m ² per)
κ Carrageenan 0.36g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified styrene-butadiene latex (SBR), Tg 7 ° C.) 3 g (solid content 1.2 g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription B / 1m ² per)
κ Carrageenan 0.36g
SR130 (Nippon A & L Co., Ltd., unmodified SBR latex, Tg-6 ° C)
2.4 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription C / 1m ² per)
κ Carrageenan 0.36g
MR171 (Nippon A & L Co., Ltd., carboxyl-modified methyl methacrylate butadiene latex (MBR), Tg-5 ° C.) 2.4 g (solid content 1.2 g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formulation D / 1m ² per)
κ Carrageenan 0.36g
MR180 (Nippon A & L Co., Ltd., unmodified MBR latex, Tg-12 ° C)
2.4 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription E / 1m ² per)
κ Carrageenan 0.36g
LACSTER 7200 (manufactured by DIC Corporation, carboxyl-modified MBR, Tg 15 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription F / 1m ² per)
κ Carrageenan 0.36g
Juliano W321 (Arakawa Chemical Industries, Ltd., urethane polyether latex, carboxyl group-containing, Tg-60 ° C.) 3.4 g (solid content 1.2 g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription G / 1m ² per)
κ Carrageenan 0.36g
Rikabond FK264 (Chuo Rika Kogyo Co., Ltd., acrylic latex, Tg-2 ° C)
2.7 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formulation H / 1m ² per)
κ Carrageenan 0.36g
S-752 (Sumitomo Chemical Co., Ltd., ethylene / vinyl acetate / latex, Tg 15 ° C.)
2.4 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Comparison undercoat layer formula I per 1m ² )
κ Carrageenan 0.36g
SR100 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 25 ° C.)
2.4 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Comparison undercoat layer prescription J / 1m ² per)
κ Carrageenan 0.36g
DS-205 (manufactured by DIC Corporation, carboxyl-modified SBR latex, Tg 40 ° C.)
2.4 g (1.2 g solid content)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Comparison undercoat layer prescription K / 1m ² per)
κ Carrageenan 0.36g
AP-40 (Nippon A & L Co., Ltd., polyester urethane latex, Tg 49 ° C)
6g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Comparison undercoat layer formulation L / 1m ² per)
κ Carrageenan 0.36g
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Comparison undercoat layer formulation M / 1m ² per)
PA 9281 3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

<Support side porous hydrophilic layer formulation / per 1 m ² >
Silica dispersion (as solids) 260mg
Glyoxal (37% aqueous solution) 7mg
κ Carrageenan 140mg
Activator (coating aid) 5mg

<Surface-side porous hydrophilic layer formulation / per 1 m ² >
Silica dispersion (as solids) 8mg
κ Carrageenan 2mg
Glyoxal (37% aqueous solution) 0.1mg
Surflon S-132 (manufactured by Seimi Chemical Co., Ltd., fluorine-containing surfactant)
0.2mg

An ink for an ink jet printer was prepared according to the following formulation, and this was put into a black ink of PM-750C (manufactured by Seiko Epson Corp.) and printed on the prepared lithographic printing plate precursor. After printing, the printed part was exposed for 15 seconds with a high-pressure mercury lamp (80 W / cm ² , power supply 1 kW) and cured.

<Ink composition containing ultraviolet curable resin>
10 g below
10 g below
Edible blue No. 1 0.4g
Darocur 1173 (manufactured by Ciba Specialty Chemicals)
2g
Ethanol 57.6g
20g of water
Dissolve completely with ethanol, and then add water to bring the total volume to 100 g.

  Using the obtained printing plate, printing was performed with an offset printing machine (3200CD manufactured by Ryobi Magics Co., Ltd.).

The soiled state and printing durability of the printed material were evaluated according to the following criteria.
<Evaluation of dirt on printed matter>
1: Not dirty at all.
2: Partially dirty.
3: The entire surface is thin and dirty.
4: The entire surface is dirty.
<Evaluation of printing durability of printed matter>
1: Print image does not change at all.
2: The printed image is hardly changed, but the 3% halftone image of 360 dpi 100 lines is thin.
3: The printed image is hardly changed, but the 6% halftone image of 360 dpi 100 lines is thin.
4: The ink density in the image area is lowered and the thin line portion is thinned.

The moisturizing liquid and ink used for evaluating the soiled state and printing durability of the printed material are shown below.
<Evaluation of dirt>
1: Moisturizer Nitro Chemical Co., Ltd. Astro Mark III 1% (Use water supply to make 1%.)
2: Ink Dai Nippon Ink Chemical Co., Ltd. New Champion Purple 68N
<Evaluation of printing durability>
1: Dampening solution Mitsubishi Paper Industries SLM-OD30 3% (Use water supply to make 3%.)
2: Ink Dai Nippon Ink Chemical Co., Ltd. New Champion Ink 85H
The dirt state was evaluated based on the dirt state of the 1000th blanket. Printing durability was evaluated after 10,000 sheets were printed. In addition, the 100th printed material in the printing durability test was visually checked for blurring in the image, and “O” indicates that there is no blur, “Δ” indicates that it is generated, and “X” indicates that the blur is generated. These results are shown in Table 1.

  From Table 1, it can be seen that unless the Tg of the latex is lower than 20 ° C., the printing durability is lowered, and further, the latex having a Tg of 10 ° C. or less is more preferable. It can also be seen that anionic latex is preferable to nonionic latex.

  The test was conducted in the same manner as in Example 1 except that an undercoat layer having the following formulation was used instead of the undercoat layer of Example 1. As a result, it became as shown in Table 2.

(Undercoat layer formulation A2 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer prescription B2 / 1m ² per)
κ Carrageenan 0.7g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formulation C2 / 1m ² per)
κ Carrageenan 0.6g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Per undercoat layer formulation D2 / 1m ² )
κ Carrageenan 0.12g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formulation E2 / 1m ² per)
κ Carrageenan 0.1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formula F2 / 1m ² per)
κ Carrageenan 0.05g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glyoxal (37% aqueous solution) 0.01g
Activator (coating aid) 1g

  From Table 2, when the ratio of the polymer latex having a Tg of 20 ° C. or less with respect to the water-soluble polymer is 1 to 30, a practically sufficient printing result is obtained, and when the ratio is 2 to 10 It can be seen that printing durability and dirt are good.

  The test was conducted in the same manner as in Example 1 except that an undercoat layer having the following formulation was used instead of the undercoat layer of Example 1. As a result, it became as shown in Table 3.

(Undercoat layer formulation A3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
0.01 g formaldehyde (37% aqueous solution)
Activator (coating aid) 1g

(Undercoat layer formulation B3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Glutaraldehyde (25% aqueous solution) 0.01g
Activator (coating aid) 1g

(Undercoat layer formulation C3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
SRAU (Sumitomo Chemical Co., Ltd., ethylene urea N-methylol)
0.05g
Activator (coating aid) 1g

(Undercoat layer formulation D3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Dimethylol urea 0.02g
Activator (coating aid) 1g

(Undercoat layer formulation E3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
Bis (vinylsulfonylmethyl) ether 0.02g
Activator (coating aid) 1g

(Comparison undercoat layer prescription F3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
EX313 (Epoxy hardener made by Nagase Chemtex)
0.02g
Activator (coating aid) 1g

(Comparison undercoat layer prescription G3 / 1m ² per)
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
DURANATE WB40D (isocyanate hardener made by Asahi Kasei)
0.02g
Activator (coating aid) 1g

(Comparison undercoat layer formulation per H3 / 1m ² )
κ Carrageenan 1g
PA 9281 (Nippon A & L Co., Ltd., carboxyl-modified SBR latex, Tg 7 ° C.)
3g (solid content 1.2g)
2,4-dichloro-6-hydroxy-S-triazine
0.02g
Activator (coating aid) 1g

  From Table 3, it can be seen that the planographic printing plate using the aldehyde hardener and the active vinyl hardener is more soiled and smeared.

  An image is printed with black ink of a UV printer UJF-604 (Mimaki Co., Ltd., equipped with a UV irradiation device next to an inkjet head) using the plates NoA-1 and A-2 prepared in Example 1. Evaluation was made in the same manner as in Example 1. As a result, both printing durability and soiling were evaluated as 1, and no bleeding occurred. Although the printer is expensive, it has been found that good results can be obtained using a non-aqueous UV inkjet printer.

  In the same manner as in plate NoA-1 in Example 1, undercoat formulation A was applied to RC paper, and the coating liquid prepared with the support-side porous hydrophilic layer formulation used in Example 1 was applied to the coating amount (solid content). The surface side porous hydrophilic layer used in Example 1 was further applied thereon to prepare lithographic printing plate precursors D-1 to D-5. As a result of evaluating this in the same manner as in Example 1, it was as shown in Table 4.

It can be seen from Table 4 that the solid content of the porous hydrophilic layer is most preferably 0.2 to 2.0 g / m ² .

Claims (3)

  In a lithographic printing plate precursor for printing an ink composition containing an ultraviolet curable resin by an inkjet method, an undercoat layer containing a water-soluble polymer and a polymer latex having a Tg of 20 ° C. or lower on the support, and further A lithographic printing plate precursor having a porous hydrophilic layer as an upper layer.   The lithographic printing plate precursor as claimed in claim 1, wherein a mass ratio of the polymer latex content to the water-soluble polymer content in the undercoat layer is 1 to 30.   The undercoat layer further contains at least one crosslinking agent selected from an aldehyde-based crosslinking agent, a crosslinking agent containing a methylol group, and an active vinyl crosslinking agent. A lithographic printing plate precursor.