JPH0579978B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing printing plates for offset printing. More specifically, the present invention relates to a novel plate-making method for directly obtaining a printing plate for offset printing from image information output in the form of an electrical signal obtained from a layout scanner without using a silver salt photosensitive material for plate-making such as lithium film. BACKGROUND ART In recent years, the speed and efficiency of printing has been increasing, and there is a desire for speed and efficiency of plate making in the printing process. In order to meet this demand, color scanners were introduced that quickly perform color separation, color correction, and halftone scanning of color originals in one step, and were able to produce halftone negatives or halftone positives for printing onto printing plates with high efficiency. However, like product advertising printing,
When a complex layout that includes illustrations, flat sheets, marks, characters, etc. in addition to color originals is required, the complicated work of so-called pasting becomes necessary, and this work becomes an impediment to improving the efficiency of the plate-making process. There is. Under these circumstances, the image information output of many types of originals such as color originals, illustrations, marks, characters, etc. converted into electrical signals obtained from a color scanner or monochrome scanner is used as an input signal, and this input signal is further converted into an electronic circuit. By processing with
A layout that can output image information as electrical signals after completing most of the conventional plate-making processes such as color separation, color correction, retouching, contact printing, stripping, filling, pasting, printing, and halftone printing. Sukiyana has appeared. Currently, the only layout scanner with this type of function is Crossfield's Magnus Scanner.
570, Hell's Chromacom, and Sitex's Response 300, all of which use output signals to control the xenon lamp beam or laser beam to scan and expose image information onto the lithium film. In these systems, to obtain a printing plate for offset printing, a lithium film that has been scanned and exposed is developed, fixed, washed with water, and dried, and then brought into close contact with a plate material and exposed to a plate-making light source such as a metal halide lamp, and then exposed again. This requires a complicated process in which the finished plate material must be developed. Naturally, the printing plate is essential for offset printing, but the process related to the above-mentioned lith film that exists between the layout scanner printing plate and the plate-making process is not always necessary. Not necessary. In fact, if this step could be eliminated, printing plates could be obtained directly from the manuscript using a layout scanner, which would not only make it possible to maximize the efficiency of the plate-making process, but also allow for the use of lithographic film. By not using it, plate making costs can also be reduced. Furthermore, in the plate-making process, it is no longer necessary to use silver salt photosensitive materials, which have conventionally been used in large quantities, for anything other than the original film, which contributes to resource conservation of precious metals such as silver. Therefore, the present inventor conducted extensive research to find a plate-making method that can directly obtain a printing plate from the output of a layout scanner without going through the process related to the above-mentioned lithographic film, which is originally unnecessary. The present invention relates to an image converted into an electrical signal obtained by a layout scanner on a plate substrate coated with an electron beam curable composition containing a curable resin having an ethylenically unsaturated bond. This is a method of manufacturing a printing plate for offset printing, characterized by scanning irradiation with an electron beam controlled by information output. In the present invention, as the base material, the same base material used in the production of general offset printing plates can be used, but the electron beam curable composition applied on the base material The surface of the base material is made to have extremely fine irregularities so that it hardens and adheres tightly through irradiation, increasing printing durability and improving water retention during printing after being made into a printing plate. Preferably, it is made of aluminum, zinc, chrome plated plate, etc. with a grained surface. In addition, as for the graining method, use a polishing ball of an appropriate size (glass, ceramic, steel, etc.) and an abrasive (garnet, carborundum, alundum, etc.)
Also, the beading method uses water and vibration to make small scratches on the metal surface, the method of blowing wet abrasive onto the metal surface with compressed air, the brushing method, anodizing method, boehmite treatment, and combinations of these methods. However, in order to improve water retention during printing, adhesion with the electrocurable composition cured by electron beam irradiation, and printing durability associated with it, further anode treatment is required after mechanical polishing such as the doweling method or brushing method. It is preferable to use a method of oxidation or boehmite treatment. More preferably, if an aluminum plate roughened by electrolytic polishing is further anodized, it is possible to easily adjust the water content and obtain a printing plate with excellent reproducibility and printing durability. In the present invention, the electron beam curable composition to be applied onto the substrate is a resin having an ethylenically unsaturated bond such as an acrylate resin and having the property of causing radical polymerization and curing by electron beam irradiation. It is an essential condition that the electron beam curable composition contains the following properties. 1. Good adhesion to base materials including rough metal surfaces such as aluminum and chrome plating. 2. The ink receptivity should be good after curing and fixation. The printing durability of the part after hardening and fixation should be good. 3 Rapid hardening and fixation by irradiation with electron beams. In order to fully satisfy the above properties, the electron beam curable composition must contain (A) 30 to 80 parts by weight of a curable resin, (B) 5 to 50 parts by weight of a reactive diluent, and (C) a heat-curable composition. In order to achieve the object of the present invention, it is preferable to have a composition consisting of 0 to 1 part by weight of a polymerization inhibitor and, if necessary, 60 parts by weight or less of (D) a pigment. Among the curable resins related to the present invention, (a) general formula

A 5-membered ring compound having a double bond represented by the formula (wherein R represents an organic residue having 1 to 3 carbon atoms and n represents an integer of 0 or 1 to 6) and/or
Alternatively, a resin having a hydroxyl group obtained by reacting these Diels-Alder reaction products with (b) a compound having both a polymerizable double bond and a hydroxyl group in the same molecule, or hydrogen added to the resin as necessary. The curable resin obtained by esterifying acrylic acid and/or methacrylic acid to a resin having added hydroxyl groups contains cyclopentadiene, dicyclopentadiene, tricyclopentadiene, tetracyclopentadiene, and carbon as component (a). One or more selected from the group consisting of lower alkyl substituents of numbers 1 to 3, and (b) component, (meth)allyl alcohol, 2-hydroxyethyl (meth)acrylate, 2-hydroxy (a) one or more selected from the group of propyl (meth)acrylate, butenediol, etc.
The molar ratio of component/component (b) is between 30/70 and 95/5, preferably between 40/60 and 80/20, in the presence of a radical polymerization catalyst or without a catalyst, if desired in a solvent such as xylene. A resin having a hydroxyl group is obtained by heating the reaction at 150 to 350°C in the presence of the resin, and if necessary, the resin having a hydroxyl group is hydrogenated to form a so-called resinous resin whose majority is composed of diol with a molecular weight of 300 to 500. It is obtained by forming a polyol and then subjecting it to an esterification reaction with acrylic acid and/or methacrylic acid. In the above process, the hydrogenation conditions must be carefully selected, and it is preferable to use a noble metal catalyst such as platinum or palladium.
It is preferable to carry out the hydrogenation under the condition of 100 Kg/cm ² without reducing the amount of hydroxyl groups. The degree of hydrogenation is usually 40% or more, preferably 60% or more of the carbon-carbon double bonds of the resin (resinous polyol) having hydroxyl groups, to obtain an extremely clear hue and stability after electron beam curing. A product that gives a good cured film has been obtained. Further, the reaction between the resin having a hydroxyl group and acrylic acid and/or methacrylic acid is carried out under normal esterification reaction conditions in the presence of a catalyst or without a catalyst. At this time, it is preferable to react acrylic acid and/or methacrylic acid in an amount of 0.5 to 1 molar equivalent per hydroxyl group 1 of the resin having a hydroxyl group. Another example of the curable resin according to the present invention is an acrylate and/or methacrylate obtained by esterifying a polyol with acrylic acid and/or methacrylic acid [these are referred to as (meth)acrylates]. ] These are obtained by esterifying acrylic acid and/or methacrylic acid with polyols such as various glycols, trimethylolpropane, pentaerythritol, dipentaerythritol, and polypentaerythritol. However, (meth)acrylate obtained by esterifying these polyols with acrylic acid and/or methacrylic acid alone does not have the necessary viscosity, flow characteristics, and flexibility and toughness of the film after electron beam curing. unsaturated polyester resin, conjugated drying oil, epoxy resin, urea formaldehyde resin, allyl sulfonamide formaldehyde resin, cetyl vinyl ether, and diallyl phthalate prepolymer, or their Mixture above (meta)
It is desirable to add 70 to 30 parts by weight to 30 to 70 parts by weight of acrylate to compensate for these drawbacks. Other examples of the curable resin related to the present invention include:
There are polyester resin-based acrylates and/or methacrylates, which are obtained by esterifying acrylic acid and/or methacrylic acid with modified alkyds, polyesters, etc., which have conventionally been used as vehicles for inks. In other words, oil,
or fatty acid-modified alkyd with excess hydroxyl groups,
Alternatively, it can be obtained by subjecting acrylic acid and/or methacrylic acid to an esterification reaction on a polyester resin with excess hydroxyl groups. Other examples of the curable resin related to the present invention include:
There is (meth)acrylate, which is the esterification reaction of acrylic acid and/or methacrylic acid to a compound having an epoxy group. It is obtained by esterifying methacrylic acid, and is characterized by its smooth curing properties and the ability to form a very tough film with excellent solvent resistance. Other examples of the curable resin related to the present invention include:
There are urethane-modified acrylic resins and/or methacrylic resins, which are made by combining hydroxyl-excess alkyd or polyester with hydroxyl-containing acrylic ester and/or hydroxyl-containing methacrylic ester, toluene diisocyanate,
It is obtained by bonding with a diisocyanate such as isophorone diisocyanate. In the present invention, vinyl compounds are preferred as the reactive diluent, and (meth)acrylic acid derivatives are preferred in view of the requirements for reactivity, solubility, and low viscosity. Examples of such acrylic acid derivatives include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6- Esterification reaction of acrylic acid or methacrylic acid to hexanediol (meth)acrylate, alkyl (meth)acrylate (alkyl group with 1 to 18 carbon atoms), monohydric phenol or polyhydric phenol with alkylene oxide added to the hydroxyl group. Crosslinkable monomers such as styrene, allyl alcohol ester, glycidyl (meth)acrylate, etc. can be used. In the present invention, the pigment is not particularly limited, and organic pigments and inorganic pigments used in ordinary paints and printing inks can be used. Pigments do not necessarily have to be added, but they can be added in order to confirm and correct the condition when applied to the base material, and to confirm and correct the condition of the image when the plate material is developed. are used to adjust the rheological properties of the curable composition to ensure good transfer onto the substrate during application with a printer or coater. In the present invention, polymerization inhibitors that are effective for acrylic and/or methacrylic compounds can be used as they are, but hydroquinone and its derivatives, tetramethylthiuram disulfide, N-nitrosophenylhydroxyamine, etc. Particularly effective are aluminum salts. In preparing the electron beam curable composition in the present invention, (1) the curable resin is (2) made into a varnish with a reactive diluent, (3) a thermal polymerization inhibitor is added, and (4) as necessary. Disperse and knead together with pigment using a three-roll mill or the like. As the dispersion method, a so-called flushing method may be used depending on the case. Then, the tack value at 400rpm 30℃ is 5~20, and the flow value for 60 seconds at 25℃ is 15~20.
Prepare by adjusting. It goes without saying that other organic solvents, fillers, additives, etc. can be added as necessary during the above operations. In addition, after applying the above-mentioned curable resin dissolved in an organic solvent such as a ketone type, an ester type, or an aromatic type onto a base material, the organic solvent is evaporated off using a conventional method, and then the curable resin is dissolved on the base material. A plate material can also be produced by forming a solid curable resin layer. Moreover, at this time, the above-mentioned pigment may be added as necessary. In the present invention, the method of applying the electronically curable composition onto the substrate is a so-called solid printing method using a normal offset printing machine or a letterpress printing machine, or a gravure coater used for normal clear coating. Although it is preferable to use a coating method using a roll coater, the method of application is not particularly limited. Furthermore, if the thickness of the applied electron beam curable composition film is extremely thin, the reproduction accuracy of the image after development will be poor, and furthermore, the printing durability will be poor. On the other hand, if it is too thick, the workability of the developing process will be poor, so
A coating thickness of 50 μm is preferred. In the present invention, the electron beam irradiation device consists of a high voltage generator, an electron gun, an acceleration tube, an aperture, an electron lens, a controller, a planking unit, a vacuum device, etc., and the electron beam is irradiated onto the plate material as a minute spot. After being focused by an electron lens, the electron beam is emitted outside the electron beam irradiation device through a titanium foil window and reaches the plate surface. Note that when the titanium foil described above is not used, it is necessary to maintain the entire electron beam irradiation device and scanned irradiation area in a high vacuum. Further, the image information output from the layout scanner in the form of an electric signal is input to the controller via the interface to generate a signal for turning on and off the electron beam. The on/off signal generated by the controller operates a blanking unit to control the electron beam current and the electron beam irradiation dose to the plate material during scanning irradiation. In addition,
The electron beam irradiation dose depends on the thickness of the electron beam curable composition on the substrate, but it is 1 to 1 to ensure that the obtained plate material has excellent performance in terms of image reproduction accuracy and printing durability after development. 20 megarads is preferred. In the present invention, the method of scanning the electron beam onto the plate material is not particularly limited, and generally, it is carried out by moving only one of the plate material or the electron beam, and by moving both. There is a method. At this time, the plate material can be made into a flat shape or can be wrapped around the surface of a cylindrical drum to make it into a curved shape. However, from the point of view of the simplicity of the scanning mechanism, the plate material is wrapped around the surface of a cylindrical drum, and the cylindrical drum is rotated in the circumferential direction without moving the electron beam, and at the same time, the cylindrical drum is also moved in the direction of the rotation axis. A method in which the entire surface of the plate material is scanned and irradiated is preferred. In addition, the electron beam irradiation device is equipped with an electromagnetic deflector,
It is also possible to scan and irradiate the entire surface of the plate by scanning the electron beam in one side direction of the plate using the deflector and simultaneously moving the plate in a direction perpendicular to the direction. Here, the advantage of using an electron beam as a curing means is that controllability using image electrical signals is much better and easier than with actinic rays such as ultraviolet rays, and furthermore, the penetrating power of electron beams is strong, so for example, ultraviolet curing Compared to the case of UV irradiation using a transparent composition, solidification and hardening progresses more quickly to a deeper part, exhibiting extremely good adhesion to the substrate and at the same time speeding up scanning. Since it does not contain a low molecular weight photopolymerization initiator unlike the ultraviolet curable composition, when printing using the printing plate according to the present invention, the cured film of the electron beam curable composition, which is the image area, is removed. Since there are no components extracted by the ink used in the printing process, the above-mentioned hardening effect extends deep into the interior, and together with this, extremely excellent printing durability is achieved. Further, the hardened and fixed portion has sufficient affinity for ink. That is, a printing plate is provided which provides printed matter with good ink receptivity to general oil-based printing inks and general ultraviolet curable printing inks as images and excellent image reproducibility.
In addition, in offset rotary printing where printing durability is strongly required, a printing plate having printing durability comparable to that of a multilayer metal plate can be produced. In the present invention, the plate material after electron beam irradiation is developed by utilizing the difference in solubility in a solvent between the cured portion and the uncured portion of the electron beam curable composition. General organic solvents can be used as the developing solvent, but developability,
From the viewpoint of workability, etc., it is preferable to use so-called ketone, ester, or aromatic solvents.
In addition, for the above-mentioned development treatment using an organic solvent, the uncured portions are removed by wiping the plate with a sponge or other material that does not cause damage to the plate surface soaked in the organic solvent, or the organic solvent is showered onto the plate. It is preferable to use a method in which the uncured portion is removed by spraying it in the form of a spray to wash away the uncured portion, but there is no particular limitation on the method for removing the uncured portion when developing with an organic solvent. Incidentally, after the residual solvent on the plate material after development is removed by evaporation by a conventional method, a printing plate is obtained. According to the present invention, offset printing can be performed directly from the output of image information converted into electrical signals from a layout scanner without using silver halide materials for plate making such as lithium film, and which has excellent printing durability and image reproduction accuracy. A printing plate is manufactured. The following is a description using comparative examples and examples.
(In the examples, parts indicate parts by weight.) Comparative example From multiple color transparent originals with abstract patterns,
Color scanner (Chromagraph C299 manufactured by Hell)
Using a layout scanner (Response 300 manufactured by Cytecs), the laid out image for an indigo ink printing plate was separated into line numbers on a lithium film for argon laser (CCSL-4 manufactured by Dupont).
After scanning exposure with 150 lines, the lithographic film was developed using an automatic processor, fixed, washed with water, and dried to obtain a lithographic film having a positive image. Positive type PS for offset printing of the treated lith film
Properly expose the plate (GAP- manufactured by Fuji Photo Film Co., Ltd.) using a conventional method (exposure for 45 seconds at 1.5 m using a 3 kW metal halide lamp manufactured by Ushio Electric Co., Ltd.), and then automatically remove the PS plate after exposure. Appropriate development processing was carried out using a developing machine, and further drying processing was carried out to obtain an indigo ink printing plate P. Example 1 132 parts of dicyclopentadiene with a purity of 97%, 58 parts of allyl alcohol, and 110 parts of commercially available mixed xylene were charged into an autoclave equipped with a stirrer, and the temperature was 260.
After the reaction was completed for 5 hours at <RTIgt;C,</RTI> the autoclave was cooled and the contents were distilled to remove unreacted monomers, low polymers, and xylene, yielding 152 parts of Resin ()-1. 100 parts of this resin ()-1 was dissolved in commercially available mixed xylene, and the palladium concentration was 5.
% palladium carbon (5% Pdc standard product made by Nippon Engelhard) was added, and the hydrogen pressure was 30 kg/
A hydrogenation reaction was carried out at 150°C ^for 1 hour, and the solvent was distilled off to obtain water-added resin (2)-1. The properties of Resin ()-1 and Resin ()-1 are as follows.

[Table] Next, 80 parts of resin ()-1, 20 parts of acrylic acid,
1.0 part of para-toluene sulfonic acid and 0.1 part of hydroquinone were added to a cooling machine with a side arm and a stirrer 4.
Pour into a neck flask and heat at 100℃ under reflux of benzene/methyl isobutyl ketone (MIBK) mixed solvent.
After reacting for 12 hours, benzene and MIBK were distilled off at 120°C to obtain resin (A)-1. Resin (A)-2 was also obtained by reacting Resin ()-1 with methacrylic acid at the same time as Resin ()-1. Next obtained resin (A)−
Varnish A and Varnish B were prepared by dissolving 70 parts each of 1 and (A)-2 in 30 parts of trimethylolpropane triacrylate. Furthermore, using the above varnish A, an electron beam curable composition A was prepared using a triple roll according to the following recipe. In addition, the tack value below is 400r.pm30℃
Flow values mean 60 seconds at 25°C. Varnish A 52 parts Bisphenol A ethylene oxide adduct diacrylate 33.9 parts Carmine 6B (T) (red pigment manufactured by Toyo Ink Manufacturing Co., Ltd.) 13 parts Organic pentonite 1 part N-nitrosophenylhydroxyamine aluminum salt 0.1 part Tack value: 12.0 Flow value: 17.0 The electrocurable composition A thus obtained was grained by electrolytic polishing using a so-called PS blank plate as an original plate, and then grained by electrolytic polishing. Plate material A was printed on a 300 μm thick oxidized aluminum plate with a film thickness of 5 μm. Next, from the multiple color transparent originals used in the comparative example, a color scanner (Chromagraph manufactured by Hell Inc.) was used.
C299) and a layout scanner (Response 300 manufactured by Sci-Tex) to obtain image information output as an electrical signal for the indigo ink printing plate that has already been laid out, and send the electrical signal to the electron beam irradiation device via an interface. The electron beam was inputted and radiated out of the electron beam irradiation device through a titanium foil window, and the plate material A fixed on the surface of a cylindrical scanning drum was scanned and irradiated with a dose of 5 megarads. The surface of the plate material to be irradiated with the electron beam was replaced with nitrogen gas to prevent so-called air inhibition. Next, using a sponge impregnated with cellosol acetate, the surface of plate material A scanned and irradiated with an electron beam was wiped to remove the uncured electron beam curable composition, and then residual development was performed in a conventional manner. The solvent was removed by evaporation to produce a blue ink printing plate A. Example 2 Using varnish B obtained in Example 1, electron beam curable composition B was prepared in the same manner as in Example 1 with the following formulation. Varnish B 40 parts Dipentaerythritol hexaacrylate 31.9 parts Lionol Blue KL (indigo pigment manufactured by Toyo Ink Manufacturing Co., Ltd.) 3 parts Hakuenka-O (extender pigment) 25 parts Tetramethylthiraum disulfide 0.1 part Tack value 10.0 Flow Value 16.0 The thus obtained electron beam curable composition B was printed on a 300 μm thick aluminum plate whose surface had been roughened by the grinding method to a film thickness of 5 μm in the same manner as in Example 1.
And so. Next, as in Example 1, the plate material B was scanned and irradiated at a dose of 10 megarads, and the plate material B was further developed and dried in the same manner as in Example 1 to produce a printing plate B. Example 3 60 parts of diallyl phthalate prepolymer was mixed with 39.5 parts of dipentaerythritol hexaacrylate, N-
The mixture was mixed with 0.5 part of aluminum salt of nitrosophenylhydroxyamine, stirred, and heated and maintained at 90°C for 1 hour to obtain Varnish C with a viscosity of 60 poise (25°C). Using this varnish C, an electron beam curable composition C was prepared in the same manner as in Example 1 using the following formulation. Varnish C 60 parts Dipentaerythritol hexaacrylate 12 parts Mitsubishi Carbon Black MA8 (carbon black manufactured by Mitsubishi Chemical Industries, Ltd.) 10 parts Hakuenka O (extender pigment) 18 parts Tack value 8.0 Flow value 17.0 Electrons obtained in this way Line curable composition C
This was printed on a 300 μm thick aluminum plate roughened by brush polishing with a film thickness of 10 μm in the same manner as in Example 1 to obtain plate material C. Next, as in Example 1, the plate material C was scanned and irradiated at a dose of 10 megarads, and then the plate material C was developed and dried in the same manner as in Example 1 to produce a printing plate C. Example 4 20 parts of oleic acid and 47 parts of trimethylolpropane are reacted in a four-necked flask under a carbon dioxide gas stream at 240°C until the acid value reaches 5 or less. Then phthalic anhydride
Add 33 parts and react at the same temperature to obtain an alkyd resin with an acid value of 5 or less and a hydroxyl equivalent of 180. Next, 71.5 parts of this alkyd resin and 10.0 parts of benzene were added to a reflux vessel.
Pour into a four-necked flask with a stirrer, heat to 90°C, add 28.5 parts of acrylic acid, 1.0 part of p-toluenesulfonic acid, and 0.1 part of hydroquinone dropwise at 85 to 95°C while blowing air. temperature rises
The reaction was carried out at 100 to 120°C, and when the acid value reached 5 or less, benzene was removed and the mixture was pumped out. This is called varnish D. Using this varnish D, an electron beam curable composition D was prepared in the same manner as in Example 1 using the following formulation. Varnish D 51 parts Dipentaerythritol hexaacrylate 35.9 parts Carmine 6B (T) (Toyo Ink Seizo Co., Ltd. Red Color) 13 parts Hydroquinone 0.1 part Tack value 11.0 Flow value 17.0 Electron beam curable composition thus obtained D
was polished with a brush to give it a grain, and then printed on a 300 μm thick anodized aluminum plate with a film thickness of 10 μm in the same manner as in Example 1 to obtain plate material D. Next, the plate material D was scanned and irradiated with a dose of 20 megarads in the same manner as in Example 1, and then the plate material D was developed and dried in the same manner as in Example 1 to produce a printing plate D. Example 5 Epicote 828 (epoxy resin manufactured by Ciel Sekiyu Co., Ltd.)
71.7 parts, acrylic acid 28.3 parts, hydroquinone 0.1
1 part and 0.1 part of triethylenediamine were charged into a four-necked flask equipped with a reflux tube and a stirrer, and reacted at 90 to 110°C for 15 to 20 hours while blowing air. When the acid value reached 1 or less, the mixture was pumped out. This is called varnish E. Using this varnish E, an electron beam curable composition E was prepared in the same manner as in Example 1 using the following formulation. Varnish E 54 parts Bisphenol A ethylene oxide adduct diacrylate 32.9 parts Carmine 6B (T) (Toyo Ink Manufacturing Co., Ltd. Red Color) 13 parts Tetramethylthiuram disulfite 0.1 part Tack value 11.0 Flow value 16.0 In this way Obtained electron beam curable composition E
was polished with a brush to give it a grain, and then printed on a 300 μm thick anodized aluminum plate with a film thickness of 10 μm in the same manner as in Example 1 to obtain plate material E. Next, the plate material E was scanned and irradiated with a dose of 10 megarads in the same manner as in Example 1, and the plate material E was developed and dried in the same manner as in Example 1 to produce a printing plate E. Example 6 63.1 parts of pentaerythritol triacrylate is placed in a four-necked flask equipped with a reflux tube, maintained at 38 to 40°C, and 36.9 parts of toluene diisocyanate is added dropwise over 1 hour. When the residual isocyanate groups reached a constant level of around 8.7%, the reaction was stopped and the mixture was pumped out. This is called acrylated isocyanate A. Then 20 parts of oleic acid, trimethylolpropane
47 parts were reacted in a four-necked flask with a stirrer at 240°C under a carbon dioxide gas stream until the acid value became 5 or less.
Thereafter, 33 parts of phthalic anhydride was added and reacted at the same temperature for 3 hours to obtain an alkyd with an acid value of 5 or less and a hydroxyl equivalent of 180. 90 parts of this alkyd with a hydroxyl equivalent of 180, 40 parts of trimethylolpropane triacrylate, and 0.1 part of hydroquinone were mixed and dissolved, 104.4 parts of the above acrylated isocyanate A was added, and the mixture was heated at 60 to 70°C for 7 to 70 minutes.
The reaction was allowed to proceed for 9 hours, and the solution was pumped out when the residual isocyanate group became 0.27 or less. This is called varnish F. Example 1 using this varnish F with the following recipe
Electron beam curable composition F was prepared in the same manner. Varnish F 47 parts Dipentaerythritol hexaacrylate 39.9 parts Carmine 6B (T) (Toyo Ink Manufacturing Co., Ltd. Red Color) 13 parts N-nitrosophenylhydroxyamine aluminum salt 0.1 part Tack value 8.0 Flow value 17.0 Obtained in this way Electron beam curable composition F
was polished with a brush to give it a grain, and then printed on a 300 μm thick anodized aluminum plate with a film thickness of 10 μm in the same manner as in Example 1 to obtain plate material F. Next, the plate material F was scanned and irradiated with a dose of 10 megarads in the same manner as in Example 1, and then the plate material F was developed and dried in the same manner as in Example 1 to produce a printing plate F. Example 7 Varnish G was prepared by dissolving 48.5 parts of resin (A)-1 obtained in Example 1 and 51.5 parts of methyl ethyl ketone in a conventional manner. Using this varnish G, an electron beam curable composition G was prepared by milling the varnish G according to the following recipe using a ball mill until the maximum particle size of the pigment was 10 μm. Varnish G 96.9 parts Carmine 6B (T) (Toyo Ink Manufacturing Co., Ltd. Red Color) 3 parts N-nitrosophenylhydroxyamine aluminum salt 0.1 part The viscosity of the obtained electron beam curable composition G was measured using a Zankup viscometer ( No. 4 cup (25°C) for 20 seconds. Electron beam curable composition G thus obtained
was coated on a 300 μm thick aluminum plate, which had been roughened by a grinding method, using a roll coater to give a film thickness of 20 μm. Methyl ethyl ketone was removed by evaporation from the coated plate material by a conventional method to form a solid electron beam curable composition with a film thickness of 10 μm on the plate material, thereby producing plate material G. Next, the plate material G was scanned and irradiated with a dose of 10 megarads in the same manner as in Example 1, and then the plate material G was developed and dried in the same manner as in Example 1 to produce a printing plate G. Example 8 Plate material H in which a solid electron beam curable composition with a film thickness of 10 μm was formed on the plate material in the same manner as in Example 7
was manufactured. Next, plate material H is fixed on the surface of a cylindrical drum for scanning, and the inside of the electron beam irradiation device and the entire scanning irradiation area are kept in the same high vacuum system without using a titanium foil window in the electron beam irradiation device. , the plate material H was dosed in the same manner as in Example 7.
Scanning irradiation was performed at 10 megarads, and the plate material H was further developed and dried in the same manner as in Example 7 to produce a printing plate H. Next, the results of comparing the halftone reproducibility of the printing plates P and A to H obtained in Comparative Example and Examples 1 to 8 and the above printing plates P and A to H were obtained using Mitsubishi Heavy Industries' BB type off-rings. The results of a printing test using a printing machine are shown. Dot reproducibility: The dot percentage of the dot scale on the printing plate P obtained in the comparative example where the dots were resolved from the gray scale of the original was measured for each step, and the dots obtained in Examples 1 to 8 in the same manner. Printing version A~
The tint % of the tint scale on H was measured step by step. Here, for the same step of the tint point scale, the measured values of the tint percentage of printing plate P and printing plates A to H are compared for each step, and the printing plate P obtained by the conventional manufacturing method and the printing plate obtained by the present invention are compared. The tint reproducibility of printing plates A to H was compared. Note that a Beuvac (manufactured by Toyo Ink Mfg. Co., Ltd.) was used for the tint point measurement. Printing test ink used: WK LTD Indigo A (off-wheel ink manufactured by Toyo Ink Manufacturing Co., Ltd.) Paper: Top-coated paper for off-circle (manufactured by Kanzaki Paper Co., Ltd.) B
Size 66.5K Printing durability: Shown as the result of printing using printing plates P and A to G on a BB type off-wheel printing machine manufactured by Mitsubishi Heavy Industries. Ink receptivity: Ink transfer on printed matter printed with the above WK LTD Indigo A was visually judged.

【table】

[Table] The printing plate manufactured according to the present invention as described above has the following characteristics compared to the commonly used commercially available PS plate:
It can be seen that it has comparable performance in terms of printing durability, dot reproducibility, and ink receptivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of the printing plate manufacturing process of the present invention, from the original to the electron beam scanning irradiation unit onto the plate material. FIG. 2 is a schematic diagram of the configuration of the present invention in the case where a titanium foil window is not used in the electron beam irradiation device, and the electron beam irradiation device and the entire scanned irradiation area are kept in the same high vacuum system for plate making. Each symbol in the figure is as follows. 1...Color scanner, 2...Document scanning section, 3...Document, 4
...Image processing unit, 5...Layout scanner image processing unit, 6...Interface, 7...Controller, 8...Blanking unit, 9...
Electronic lens, 10... High voltage generator, 11...
Electron beam gun, 12... Acceleration tube section, 13... Vacuum pump, 14... Titanium foil, 15... Electron beam, 1
6... Scanning irradiation section, 17... Plate material, 18... Nitrogen gas circulation device.

Claims (1)

[Claims] 1. On a plate base material coated with an electron beam curable composition containing a curable resin having an ethylenically unsaturated bond,
A method for producing a printing plate for offset printing, characterized by scanning and irradiating with an electron beam controlled by image information output converted into an electric signal obtained from a layout scanner.