JPH0356464B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a dry direct printing planographic printing plate using a planographic printing plate. Direct lithography (hereinafter referred to as dilithography) is a method that traditionally uses dampening water to print a photosensitive lithographic plate (presensitized plate).
plate, hereinafter referred to as PS version. ) has been put to practical use in newspaper printing and other applications. When using a general planographic printing plate for die lithography, dampening water and ink are supplied to each plate, and printing is performed by bringing the plate and printing material into direct contact. However, this method is difficult due to the difficulty in adjusting the water supply. This method is not suitable as a method for obtaining high-quality printed materials because it causes variations in printing, and because it is a lithographic plate, the printing pressure does not increase very much, which inevitably leads to a decrease in image quality due to poor ink transfer. On the other hand, a method that does not use dampening water has also been put into practical use, but in this case, a plate having a non-image area made of an ink-repellent material and an image area made of an ink-philic material is used, so the dampening solution is not used. Since water is not required and dampening water is not used, phenomena such as distortion of the printing paper and emulsification of the ink do not occur, and stable printing can be performed with high printing density.However, the printing pressure cannot be increased. In addition, deterioration in image quality due to poor ink transfer is unavoidable, and although printing stability is somewhat improved compared to wet dye lithography, even dry dye lithography cannot produce printed matter worthy of the name of high-quality prints. Dilithographic printing, whether dry or wet, is superior to letterpress printing for things such as halftone photo printing, but is far inferior to offset printing; In this case, it is slightly better than offset printing, but the reality is that it is inferior to letterpress printing. Furthermore, among ordinary printing methods, offset printing is superior in terms of smoothness of the image quality of printed matter. The reason why offset printing is superior is that it uses a blanket.The ink on the lithographic printing plate is first transferred to the blanket, and then the ink is transferred from the blanket to the printing material again, so the elasticity of the rubber of the blanket The ink is transferred uniformly from the plate, and when the ink is transferred to the printing material, unevenness on the surface of the printing material is eliminated by deformation of the rubber. Therefore, printing by die lithography does not use a blanket, so the plate and the printing material do not fit well, and the transfer of ink is poor, resulting in an unavoidable drop in image quality.One way to overcome this problem is to increase the printing pressure. , the plate surface is damaged quickly and is not suitable for practical use. In printing using die lithography, one way to avoid damage to the plate surface and increase the printing pressure is to make the printing area convex and locally increase the printing pressure in the printing area. On a substrate 1 as shown, a non-image area 3 made of an ink-repellent material, and an image area 2 made of an ink-philic material that is relatively thicker than the non-image area exposed in the non-image area. It is necessary to use a printing plate having a lithographic printing plate, and the present invention relates to a method for manufacturing such a lithographic printing plate. There are various methods for producing a printing plate having such a structure. Examples include a method using photosensitive silicone, a method using a mixture of silicone and a photosensitive substance, and the like. However, both methods have the disadvantage that only silicone with low ink repellency can be obtained because silicone is partially modified or mixed with foreign substances. The present invention overcomes the drawbacks of the above-mentioned conventional methods and produces a dry direct printing lithographic printing plate which has an ink-repellent non-image area made of organopolysiloxane and has excellent printability without deterioration of ink repulsion. Regarding the method. The present invention will be explained in detail below. Substrates used in the present invention include metal materials such as stainless steel and aluminum, plastic films or sheets such as polyester film, polyimide film, polycarbonate film, and cellulose acetate film, composites of these plastic films or sheets with metal, and glass fiber reinforced epoxy. Any material can be used as long as it has the mechanical strength and flatness as a substrate for a printing plate, such as a composite film or sheet. Next, to explain the layer consisting of the first and second photocurable resins provided on the substrate surface, such photocurable resins include, for example, cinnamoyl group,
A compound having a photocrosslinkable group such as a diazo group, an azide group, or an acryloyl group, or a photopolymerizable monomer such as acrylamide, an acrylic acid ester, or a mixture of diethylformate or diethyl maleate added to styrene is used as an unsaturated polyester. A resin mixed with polyurethane or the like, to which a photopolymerization initiator, stabilizer, filler, diluent, etc. are added as necessary, is used and coated using known coating methods such as gravure coating, The coating thickness is 5 μm to 100 μm, preferably 10 μm for the layer made of the first photocurable resin, by a coating method such as roll coating, spray coating, dip coating, spinner coating, spray coating, or kiss coating.
m to 70 μm, and in the case of the layer made of the second photocurable resin, the thickness is 0.1 μm to 50 μm, preferably 1 μm to 10 μm, and is dried to such an extent that there is no problem in use. As described later, by exposure to light and dissolution/removal of the uncured portion, the layer made of the first photocurable resin forms a convex image area, and the layer made of the second photocurable resin forms a separable layer on the convex image area. However, the convex image area and the separable layer have different solubility or swelling properties in specific solvents,
The first, so that only the detachable layer dissolves or swells.
It is necessary to select the second photocurable resin and the solvent. For example, a diazo/PVA resin (Super King BS, manufactured by Tokyo Ohka Kogyo) is selected as the first photocurable resin, and an azide resin (FPER, manufactured by Fuji Pharmaceutical Co., Ltd.) is selected as the second photocurable resin. ) and using methyl ethyl ketone as a solvent.
Examples of the photocurable resin and solvent include the following combinations.

【table】

[Table] As described above, the layer made of the first photocurable resin on the surface of the base material and the layer made of the first photocurable resin have a high solubility or swelling property in a solvent after photocuring. A plate material is obtained in which layers made of different second photocurable resins are sequentially provided. Next, pattern exposure is performed on the surface of the plate material formed as described above, on which the layer made of photocurable resin is formed. The pattern exposure may be carried out by closely holding a photographic film or by camera work, and the light for pattern exposure is used to harden the photocurable resin of the layer consisting of the first and second photocurable resins described above. Irradiation is performed using light of different wavelengths. The light is not particularly limited as long as it has the above performance, but preferably ultra-high pressure mercury lamps, high pressure mercury lamps,
It is preferable to use ultraviolet light from a light source such as a chemical lamp, metal halide lamp, carbon arc, or xenon arc. Next, the portions that were not cured by the above exposure are dissolved and removed. Dissolution and removal are performed on the first and second uncured parts.
The photocurable resin layers are simultaneously or sequentially dissolved and removed. For example, a solvent suitable for each resin is used for the dissolution and removal as follows.

[Table] As described above, a convex image area where a part of the layer made of the first photocurable resin is cured and remains on the substrate surface, and a second photocurable resin layer is formed on the convex image area. An intermediate product is obtained in which a part of the layer made of a polyurethane resin is cured to form a releasable layer that swells or dissolves due to the remaining solvent and is releasable. Furthermore, a layer made of organopolysiloxane is formed on the entire surface of the above intermediate body having the convex image area and the releasable layer on the convex image area. The organopolysiloxane used here is one that crosslinks and cures at room temperature or by heating after coating to become a silicone rubber elastic body, and has a high degree of polymerization in which 90 mol% or more of all organic groups bonded to silicon atoms are methyl groups. It is best to use organopolysiloxane (which has excellent ink repellency) as its main ingredient;
(1) Highly polymerized diorganopolysiloxane in which 90 mol% or more of the organic groups whose molecular chain ends are capped with hydroxyl groups are methyl groups, methylhydrodiene polysiloxane or ethyl polysilicate as a crosslinking agent,
and a condensation catalyst consisting of an organic acid metal salt, (2) a vinyl group-containing highly polymerized diorganopolysiloxane (at least 90 mol% of organic groups other than vinyl groups are methyl groups), and a methylhydrodiene polysiloxane as a crosslinking agent. siloxane and a platinum-based catalyst as an addition reaction catalyst, (3) a highly polymerized diorganopolysiloxane in which both ends of the molecular chain are blocked with hydroxyl groups and 90 mol% or more of the organic groups are methyl groups, and crosslinked. Examples of the agent include silanes or low polymerization degree siloxane compounds having three or more hydrolyzable groups such as acetoxy groups, amino groups, oxime groups, or propenoxy groups in one molecule. In the present invention, the types exemplified in (1) or (2) above are particularly suitable. The method for applying the organopolysiloxane described above can be the same as that for providing the layers made of the first and second photocurable resins described above. Further, the above-mentioned organopolysiloxane can be cured by leaving it at room temperature or by heating it in an oven. If the adhesion between the organopolysiloxane and the non-image area substrate is poor, it can be improved by pretreatment with a crosslinking agent such as a silane coupling agent or an organic titanate. Next, the above organopolysiloxane coated and cured intermediate is developed by applying a solvent to dissolve or swell the releasable layer, and then the surface is lightly polished to release the releasable layer. At the same time, the layer made of organopolysiloxane on the releasable layer is removed. Polishing is done by rubbing with something like a soft brush, cloth, or paper, or by rotating a roll of these materials and bringing them into contact. The solvents shown in the above table can be used as the solvents used for the above development, but since the development is carried out through the layer consisting of the organopolysiloxane mentioned above by immersion in the solvent or coating, the solvent used for the development is the organopolysiloxane. It is necessary to select a material that permeates the layer made of siloxane and does not melt the organopolysiloxane. In the manner described above, the dry direct printing planographic printing plate of the present invention is obtained. Since the present invention has the above-mentioned configuration, it is possible to easily produce a printing plate with excellent printing effect, with less damage to the plate when used in dry die lithography, and with ink repellency in the non-image area. Since organopolysiloxane with excellent properties can be used without modification, the ink repellency does not deteriorate as in the case of using photosensitive silicone or a mixture of silicone and a photosensitive substance. Both steps can be carried out using known methods and materials, and therefore can be carried out industrially. The present invention will be explained in more detail with reference to Examples below. Example: A photosensitive resin solution (manufactured by Tokyo Ohka Co., Ltd., Super King BS water developable type) was applied to the surface of an aluminum plate (thickness 0.3 mm) that had been grained, degreased, and whose surface properties had been adjusted to a dry thickness of 20 μm. The photosensitive resin solution (Fuji Pharmaceutical Co., Ltd.)
Co., Ltd., EPER-100, Triclean development type) was applied and dried to a dry coating thickness of 10 μm. Next, using an ultraviolet printer equipped with a point light source of a high-pressure mercury lamp, the photographic negative was exposed for 60 seconds, and the unexposed areas of FEPR-100 (trade name) were dissolved and removed using Triclean, and then water was removed. The unexposed areas of Super King BS (trade name) were dissolved and removed using the following methods and dried to obtain an intermediate. Next, silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.)
The entire plate was dip coated with a 5% solution of KBM406 in ethylcyclohexane and dried and cured in an oven at 100°C for 10 minutes. Furthermore, thermosetting organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KS-774) is applied to the surface of the obtained intermediate.
and a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., PL-3) were mixed in a ratio of 200:1 in stock solution, coated on the entire surface to a thickness of 5 μm, and left to cure naturally. Next, the plate surface is moistened with methyl ethyl ketone to swell the FEPR-100 (trade name) part of the image area and rubbed off with soft paper to obtain a lithographic printing plate, and this lithographic printing plate is used for dry direct printing. When this process was carried out, letters and photographs could be printed clearly, and there was almost no damage to the plate surface.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a planographic printing plate for die lithography manufactured according to the present invention. 1... Board, 2... Print area, 3... Non-print area.

Claims (1)

[Claims] 1 A layer made of a first photocurable resin on the substrate surface and a layer made of the first photocurable resin are made of a second photocurable resin having different solubility or swelling properties in a solvent after photocuring. The layers of
Next, the layers made of the first and second photocurable resins are pattern-exposed and only the uncured portions caused by the exposure are dissolved and removed, so that a part of the layer made of the first photocurable resin is left on the surface of the substrate. a convex image portion that hardens and remains;
A part of the layer made of the second photocurable resin is cured on the convex image area to form a releasable layer that swells or dissolves with the remaining solvent and separates, and then,
A layer made of organopolysiloxane is formed on the entire surface, and then development is performed using a solvent that swells or dissolves the releasable layer to release the releasable layer and at the same time remove the organopolysiloxane on the releasable layer. A method for producing a dry direct printing planographic printing plate, characterized by removing a layer consisting of.