JP2001334770A - Manufacturing method for block copy sheet for planographic printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a block copy sheet for planographic printing plate which reliably prevents an elongation of the plate on a plate cylinder of a printing machine and, for example, to make the planographic printing plate which uses materials other than metal as a support body applicable of multicolor and numerous number printing, and also to manufacture the block copy sheet which satisfies printing performance and durability under strict use conditions. SOLUTION: Materials of thermosetting chemical compound or photo- hardening chemical compound are adhered externally on at least one side of the support body having an initial coefficient of elasticity not less than 350 kgf/mm2, and further covers the whole surface of the body with overcoat layer to form convex bosses which have a height from 1 to 100 μm and a center line average roughness Ra from 2 to 20 μm, and the body is used for manufacturing the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an underplate sheet for lithographic printing for preventing a lithographic printing plate from being displaced on a plate cylinder of a printing press.

[0002]

2. Description of the Related Art Generally, in a lithographic printing press,
The lithographic printing plate is wound around the plate cylinder and mechanically fixed, and printing is performed. Conventionally, as a support for a lithographic printing plate, a support made of a material such as a metal, a plastic film, and paper has been used. A lithographic printing plate using a material other than metal as a support,
Compared with a lithographic printing plate using a metal as a support, it is excellent in handling suitability, but lacks dimensional stability. In lithographic printing, the peripheral speed of the plate cylinder and the blanket cylinder are generally different, and a force for stretching the plate is continuously applied during printing. for that reason,
In the case of a lithographic printing plate using a material other than metal as a support, the plate is stretched or misaligned during printing, and it has been difficult to perform full-color printing which requires a precise positioning system.

[0003] As a solution, there is a method of fixing a plate on a plate cylinder using spray paste (Japanese Patent Laid-Open No. 56-1125).
No. 8) and a method of fixing using an adhesive (Japanese Patent Publication No. 7-42)
No. 5, Japanese Patent Application Laid-Open No. 61-104853) has been proposed, but once it is fixed to the plate cylinder, it becomes difficult to finely adjust the alignment required later. Not valid.

Further, in a lithographic printing plate using a support other than metal as a support, there is a problem that it is difficult to position the plate at the tip of the plate cylinder and fix the grip because the support is soft. As a solution to this, a positioning method provided with multi-point pins to facilitate the positioning (Japanese Patent Laid-Open No. Hei 10-24555)
No.) has been proposed, but it cannot deal essentially with the problem caused by the soft plate.

[0005] By using a sheet material having an initial elastic modulus of 300 kgf / mm ² or less, the positional accuracy and dimensional accuracy during high-speed printing are improved, and surface treatment is performed chemically or physically. By providing a fine uneven surface (matte surface) fixed to the surface, the frictional resistance between the plate cylinder and the printing plate is reduced to ensure free sliding of the printing plate and to facilitate the registration adjustment. Hanging method (JP-A-11-2
0130) has been proposed. However, it has been found that even if this technique makes it possible to align and fix the grip, it is not possible to sufficiently suppress plate elongation and displacement.

On the other hand, an underlaying sheet having an uneven surface in which specific fine projections are formed and distributed on the surface of a sheet-like substrate (JP-A-11-59012) has been proposed. The underlay sheet cuts into the back of the lithographic printing plate to suppress the plate elongation of the lithographic printing plate, and furthermore, the effect of surface irregularities enables fine positioning, but this underlay sheet is However, when printing is performed at a high printing pressure, the unevenness on the surface of the underlay sheet is easily broken, and there is a problem in durability under severe use conditions. In particular, this problem is significant because the desorbed particles fly off during desorption after printing, contaminating the surroundings and hindering the printing machine and printing performance.

[0007]

As described above, when performing full-color printing on a lithographic printing plate using a material other than metal as a support, prevention of plate growth, alignment of the plate, durability in repeated use, etc. are all required. There is no satisfactory technology, and there has been a problem that full-color printing on such a lithographic printing plate is limited to extremely few copies.

Accordingly, an object of the present invention is to reliably prevent the lithographic printing plate from elongating and being displaced on a plate cylinder of a printing press, whereby, for example, a lithographic printing plate using a material other than metal as a support. The object of the present invention is to produce an underlay sheet for a lithographic printing plate that can be applied to printing of multiple colors and a large number of sheets and can satisfy printing performance and durability under severe use conditions.

[0009]

It has been found that the above object can be achieved by the following constitutions (1) to (5).

(1) Initial elastic modulus is 350 kgf / mm ²
A method for producing an underlay sheet for lithographic printing, characterized in that a material is externally attached to at least one surface of the above support to provide a projection having a height of 1 to 100 μm when dried.

(2) The lithographic printing plate precursor as described in (1) above, wherein the projections are obtained by attaching a material from the outside and further providing an overcoat layer on the entire surface. Sheet manufacturing method.

(3) Center line average roughness Ra of the projections
The method for producing a lithographic printing underlay sheet according to the above (1) or (2), wherein

(4) The method according to any one of the above (1) to (3), wherein the material contains a thermosetting compound. (5) The method according to any one of the above (1) to (3), wherein the material contains a photocurable compound.

In the present invention, the initial elastic modulus is 350 kgf /
At least one surface of a support having a thickness of ² mm or more is provided with a convex protrusion (including a member provided with an overcoat layer) by attaching a material from the outside. The present invention, unlike the conventional underlay sheet, is to partially supply a material that becomes a convex protrusion from the outside on the surface of the flat underlay sheet,
Since an extremely small amount of material is used, the cost advantage is great, and the misregistration can be effectively prevented without substantially changing the physical properties such as the flexibility of the support.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing an underlay sheet of the present invention will be described in detail. The support used for the underlay sheet may be a sheet having an initial elastic modulus of 350 kgf / mm ² or more. For example, a metal plate, a resin sheet, a metal-resin composite sheet or the like is used, and an aluminum plate is preferable. , Zinc plate, titanium plate, metal plate such as stainless steel, copper-aluminum plate, copper-stainless steel plate, pi-metal plate such as chrome-copper plate, chrome-copper-aluminum,
Trimetal plates such as chrome-lead-iron plate, chrome-copper-stainless plate, PET sheet, PE sheet, PP sheet,
Polyester sheet, polyimide sheet, polyamide sheet, resin sheet such as acrylic resin sheet, aluminum-PET sheet, aluminum-PE sheet, aluminum-polyester sheet, titanium-PET sheet,
Metal-resin composite sheet such as titanium-PE sheet, more preferably aluminum plate, metal plate such as stainless steel, P
Examples include resin sheets such as ET sheets and PE sheets, and metal-resin composite sheets such as aluminum-PET sheets and aluminum-polyester sheets. The thickness of the support is suitably about 50 to 250 μm. The measurement of the initial elastic modulus can be performed according to JIS K7127.

In order to form a projection by attaching a material to at least one surface of the support, a projection may be formed by fixing a particulate substance on the surface of the support. The method can be achieved by a method of generating fine particles such as spraying, electrostatic coating, gravure printing, ink jet, or the like using a liquid containing a material to be formed, or a method of partially thermally transferring a projection-forming material using a heat-sensitive sheet.

In the present invention, as a material for forming the convex portion,
Acrylonitrile-butadiene-styrene resin, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cresol resin,
Carboxymethyl cellulose, nitrocellulose, cellulose proopionate, casein resin, ethyl cellulose, epoxy resin, melamine resin, poloamide, polycarbonate, ethylene trifluoride chloride resin, diallyl phthalate resin, polyethylene terephthalate, phenolic resin, polyisobutylene, methacrylic resin, polyacetal , Polypropylene, polystyrene, ethylene tetrafluoride resin, polyurethane, vinyl acetate resin, polyvinyl alcohol, polyvinyl butyral, vinyl chloride resin,
Vinyl chloride / vinyl acetate copolymer resin, vinylidene chloride,
Polyvinyl fluoride, polyvinyl formal, styrene
Acrylonitrile copolymer resin, silicon resin, urea resin, unsaturated polyester resin and the like can be used, and are used from a dissolved state or a resin emulsion state. Further, an inorganic sol-gel, a resin-inorganic sol-gel composite, or the like is also used.

Preferably, resin emulsions such as acrylic emulsions, urethane emulsions, polyethylene emulsions, vinyl acetate emulsions, and polyester emulsions; resins soluble in solvents such as acrylic resins, polyethylene, vinyl acetate, polyurethane, polyester, and polyvinyl chloride; Gel, titanium sol gel,
Inorganic sol-gel such as aluminum sol-gel, polyvinyl pyrrolidone-silica composite sol-gel, PVA-silica composite sol-gel, carboxymethylcellulose-silica composite sol-gel and other resin-inorganic sol-gel composites, more preferably acrylic emulsion, resin emulsion such as urethane emulsion, acrylic Resins, resins soluble in solvents such as polyethylene, inorganic sol-gels such as silica sol-gel, and resin-inorganic sol-gel composites such as polyvinyl pyrrolidone-silica composite sol-gel and PVA-silica composite sol-gel. In addition, these binders may cause a hardening due to the introduction of a cross-linking structure in combination with a self-cross-linking reaction and / or a cross-linking agent during dry film formation.

The weight average molecular weight of the organic polymer used in the present invention is preferably 10 ⁷ to 10 ³ , more preferably 5 to 10 ³ .
× 10 ³ to 4 × 10 ⁵ .

Further, a crosslinking agent may be added in order to improve the strength of the projection. Examples of the crosslinking agent include compounds that are usually used as a crosslinking agent. Specifically, it is described in Shinzo Yamashita, Tosuke Kaneko, "Crosslinking Agent Handbook" Taiseisha (1981), edited by The Society of Polymer Science, "Polymer Data Handbook, Basic Edition", Baifukan (1986). Can be used.

For example, ammonium chloride, metal ions,
Organic peroxides, polyisocyanate compounds (for example, toluylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylenephenyl isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, polymer polyisocyanate And polyol compounds (eg, 1,4-butanediol, polyoxypropylene glycol, polyoxyethylene glycol, 1,1,1
-Trimethylolpropane, etc.), polyamine-based compounds (e.g., ethylenediamine, γ-hydroxypropylated ethylenediamine, phenylenediamine, hexamethylenediamine, N-aminoethylpiperazine, modified aliphatic polyamines, etc.), polyepoxy group-containing compounds and epoxy Resins (eg, “New Epoxy Resin” edited by Hiroshi Kakiuchi, published by Shokodo 1985), “Epoxy Resins” edited by Kuniyuki Hashimoto, compounds described in Nikkan Kogyo Shimbun (1969), etc., and melamine resins (eg, Ichiro Miwa) , Edited by Hideo Matsunaga, "Uria Melamine Resin", compounds described in Nikkan Kogyo Shimbun (1969), etc., poly (meth) acrylate compounds (for example, "Oligomers" edited by Shin Okawara, Takeo Saegusa, Toshinobu Higashimura) Kodansha (1976), Eizo Omori "Functional acrylic resin" Techno System (1985)
And the like)).

Further, as the material for forming the convex portions, the following photocurable materials can be preferably mentioned. (A1) Unsaturated polyester containing unsaturation due to dibasic acid or polyhydric alcohol in the polymer main chain, a liquid photocurable substance obtained by combining dibasic acid and polyhydric alcohol, As the acid, maleic anhydride, phenolic acid, itaconic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride , Pyromellitic anhydride, etc., as polyhydric alcohols, ethylene glycol, propylene glycol, butanediol 2,3,
Butanediol 1,3, neopentyl glycol, butanediol 1,4, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin trimethylolpropane, polyethylene glycol, polypropylene glycol and the like.

(A2) Acrylic and methacrylic ester polyfunctional monomers, for example, methoxydiethylene glycol methacrylate, methoxytetraethylene glycol methacrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypolyethylene glycol methacrylate, 2-hydroxy-dodecyl methacrylate, 2-hydroxy Dodecyl acrylate ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, Neopen Tyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, diethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate ,
1,6-hexane glycol diacrylate, neopentyl glycol diacrylate, polypropylene glycol diacrylate, 2,2'-bis (4-acryloxy propyloxyphenyl) propane, 2,2'-bis (4-acryloxy diethoxy) Phenyl) propane,
Trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, trimenalolethane triacrylate, trimethylolmethane triacrylate,
Trimethylolpropane / monococo oil rate / diacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, pentaerythritol diacrylate, tetramethylol methane tetraacrylate, dibromoneopentyl glycol dimethacrylate, 2,3-dibromopropyl acrylate, etc. No. It is more preferable that these are exposed to light unique to photosensitivity after drying. In addition, a sensitizer, a polymerization initiator and other additives can be provided.

Further, the following thermosetting materials can be preferably used as the material for forming the convex portions. (B1) Epoxy-based materials such as halogenated bisphenol, resorcin, bisphenol F, tetrahydroxyphenylethane, novolak, polyalcohol, polybricol, glycerin triether, polyolefin, epoxidized soybean oil, and vinylcyclohexene dioxide type epoxies And polyolefins. Epoxidized soybean oil can be cured with organic acids (eg, phthalic acid, maleic acid, sebacic acid, etc.) and their anhydrides and organic peroxides (eg, benzoyl peroxide, phthaloyl peroxide, etc.). (B2) diallyl phthalate-based materials, for example, diallyl orthophthalate, diallyl isophthalate, diallyl chlorendate, etc., and cured by combining these with an organic peroxide (for example, benzoyl peroxide, phthaloyl peroxide, etc.) Speed is improved.

(B3) Urea, melamine-based material, for example, N
-Methyl-N'-methyloluron ethyl thioether, N-ethyl-N'-methylol uron ethyl thioether, N-ethyl-N'-methylol uron methyl ether, tetramethylol urea, N-methyl-N,
N ', N "-trimethylolurea, N-ethyl-N,
N ', N'-trimethylol urea, N, N'-2-methyl-N, N'-2-methylol urea, mono- and polymethylol melamine and the like. (B4) phenolic materials such as anti-roll phenol, phenol, o-methylol phenol, 2,4
-It is obtained by a curing reaction of dimethylolphenol, 2,6-dimethylolphenol or the like with formaldehyde. (B5) In addition, aniline resin-based, xylene resin-based, unsaturated polyethyl-based, and furan-based liquid thermosetting materials are all used. These materials are more preferably subjected to a heat treatment after drying.

Fine particles may be contained in the projections on the plate cylinder surface of the present invention. When fine particles are contained in the projections, it is generally preferred that the binder resin be contained in a proportion of at least 10 parts by weight, more preferably at least 30 parts by weight, based on 100 parts by weight of the particles. The above particles have a particle size of 0.
Particles having a diameter of from 0.1 to 10 μm are used, and preferably have an average particle diameter of from 0.1 to 5 μm. The material of the particles of the present invention is not particularly limited, and is a particle made of an inorganic material, an organic material, an organic-inorganic composite material, or the like.

Examples of the inorganic particles include metal powders, metal oxides, metal nitrides, metal hydroxides, metal sulfides, metal carbides and composite metal compounds thereof, preferably glass, SiO ₂ , TiO ₂ , ZnO, Fe ₂ O ₃ ,
Oxides such as ZrO ₂ and SnO ₂ and sulfides such as ZnS and CuS.

As the organic particles, for example, synthetic resin particles,
Natural polymer particles and the like, preferably acrylic resin, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, polyethylene imine, polystyrene, polyurethane, polyurea, polyester, polyamide, polyimide, carboxymethyl cellulose, gelatin, starch, chitin, chitosan, etc. And more preferably synthetic resin particles such as acrylic resin, polyethylene, polypropylene, and polystyrene.

As the organic-inorganic composite particles, for example,
At least 2 of materials forming inorganic particles and organic particles of
Or more composites, preferably glass, S
iO _Two, TiO_Two, ZnO, Fe_TwoO_Three, ZrO_Two, SnO_Two
Oxides and / or sulfides such as ZnS and CuS
Lil resin, polyethylene, polypropylene, polyethylene
Oxide, polypropylene oxide, polyethylene
Nimine, polystyrene, polyurethane, polyurea,
Polyester, polyamide, polyimide, carboxime
Chill cellulose, gelatin, starch, chitin, chitosa
And more preferably a compound such as SiO2._Two, T
iO_Two, ZnO, Fe_TwoO_Three, ZrO_Two, SnO_TwoOxidation of etc.
Resin and polyether having a hydrogen bonding functional group
Tylene oxide, polypropylene oxide, polyether
Tylene imine, polyurethane, polyurea, polyester
, Polyamide, polyimide, carboxymethyl cellulose
Complex of glucose, gelatin, starch, chitin, chitosan, etc.
Things.

The solvent for the coating liquid is not particularly limited, but when an aqueous solvent is used, a water-soluble solvent is used in combination for the purpose of uniform liquefaction by suppressing precipitation during preparation of the coating liquid. Examples of the water-soluble solvent include alcohols (methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc.) and ethers (tetrahydrofuran , Ethylene glycol dimethyl ether, propylene glycol dimethyl ether, tetrahydropyran, etc.), ketones (acetone, methyl ethyl ketone, acetylacetone, etc.), esters (methyl acetate, ethylene glycol monomethyl monoacetate, etc.), amides (formamide, N-methylformamide, Pyrrolidone, N-methylpyrrolidone, etc.). One or more solvents may be used in combination.
In the case of non-aqueous systems, it is possible to use ordinary organic solvents, and in some cases, it is effective to mix two or more.

In some cases, after the projections are provided, an overcoat layer may be further provided on the entire surface. The overcoat layer is formed of a film-forming resin, and the same one as described for the binder resin forming the concave projection is used. Preferably, a hydrophilic overcoat layer is provided on the convex portion containing the hydrophilic binder resin, and a hydrophobic overcoat layer is provided on the convex portion containing the hydrophobic binder resin so that the adhesion with the convex protrusions is good. Used.

The overcoat layer of the present invention is obtained by applying a coating solution containing the above-mentioned film-forming resin and a solvent on the above-mentioned convex projections by using a conventionally known coating method, drying and forming a film. Can be. As the solvent, the above-mentioned solvents can be used as appropriate. Examples of the coating method include coater coating (air doctor, blade, rod, squeeze, gravure, etc.), spray coating (air spray, electrostatic spray, etc.).

The surface of the support having the convex protrusions of the present invention is
The center line average roughness Ra is preferably 2 to 20 μm, more preferably 2 to 15 μm, and still more preferably 2 to 10 μm.
m.

In order to fix the underlay sheet obtained by the present invention to a plate cylinder, a conventionally known method is used. For example,
A method of applying an adhesive or a pressure-sensitive adhesive such as a spray paste or a double-sided tape to the back surface of the support of the underlay sheet, or
A method of locking the leading end and the trailing end of the underlay sheet with claw portions provided on the plate cylinder, and the like can be given. Further, a method combining these can also be used.

At the time of printing by the lithographic printing press, the lithographic printing plate is mounted on the plate cylinder via the underlay sheet of the present invention.
At this time, when the underplate sheet surface is pressed against the back surface of the lithographic printing plate, the convex protrusion acts to bite into the back surface of the lithographic printing plate. Thus, the underlay sheet can adjust the printing pressure of the blanket cylinder and the impression cylinder, and can prevent the lithographic printing plate from being displaced on the plate cylinder due to the pressurization.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 Photocurable pentaerythritol tetraacrylate (P
ETA) 80 g, methyl cellosolve 8 g, i-propyl alcohol 12 g and carbon black 0.2 g were mixed, and the resulting mixture was dispersed with an Excel auto homogenizer (manufactured by Nippon Seiki Co., Ltd.) at 10,000 rpm for 5 minutes.
From a gravure printing plate in which a 5 mm thick lead plate is provided with hemispherical cavities having a radius of 20 μm at intervals of 100 μm, a thickness of 150 μm is obtained.
m of polyethylene terephthalate (PET) film. This film was placed under a high pressure mercury lamp for 1.0 m.
Irradiation was performed for 5 minutes under a light intensity of W / cm ² to prepare an underlay sheet for lithographic printing. The center line average roughness (Ra) of the coated surface was 4.5 μm.

The plate elongation during printing was measured with a thickness of 100 μm.
A silver plate diffusion transfer photosensitive material using polyethylene terephthalate (PET) as a support and Super Master Plus (manufactured by Agfage Palte Co., Ltd., total thickness of 130 μm) was plate-produced by a dedicated plate maker SPM415.

The surface of the lithographic printing plate was uniformly treated with a sponge impregnated with a treatment liquid G671 before printing. As the dampening solution on the printing press, the treatment liquid G671 was mixed with water at a ratio of 1: 1.
The ink used was New Champi.
onF gloss 85 (manufactured by Dainippon Ink and Chemicals, Inc.) was used. Under the 130μm thick Super Master Plus printing plate, the 150μm plate underlay film created here is overlapped so that the uneven surface of the underlay film for preventing plate elongation contacts the back side of the printing plate, and the top and bottom are fixed to the plate cylinder of the printing press. And squeezed with a clamp. The ink used and the discharge amount of the dampening solution were set to the standard conditions of this system.

After printing 200 sheets, the elongation of the plate from the start of printing was actually measured on the printed coated paper. The measurement was performed on the printing plate, starting with the interval between two ruled lines drawn at intervals of 30 cm in the direction of rotation of the plate cylinder as an image on the printing plate, and actually measuring on the printed material after 2,000 sheets. It was 22 μm.

Comparative Example 1 Printing was carried out in exactly the same manner as in Example 1 except that no particle-like projections were formed on the underlaying sheet. When the plate elongation of the printing plate was measured in the same manner as in Example 1, the value was 4
It was 80 μm.

Example 2 90 g of a thermosetting resin Araldite CT200 (manufactured by Ciba-Geigy), 5 g of methyl cellosolve and 5 g of n-isopropyl alcohol were mixed and used as the lead gravure printing ink used in Example 1. In the same manner as in Example 1, printing was performed on polyethylene terephthalate (PET) having a thickness of 150 μm. This was placed in an oven at 150 ° C. and left for 5 hours to prepare an underlay sheet for lithographic printing. The center line average roughness Ra of the coated surface was 5.2 μm.

Except that this underlay sheet was replaced with that used in Example 1, printing was performed in exactly the same manner as in Example 1. When the plate elongation of the printing plate was measured in the same manner as in Example 1, the value was 18 μm.

Example 3 6 g of silica gel powder (average particle size: about 1.5 μm) and acrylic acid / methyl methacrylate copolymer (1: 1 molar ratio, molecular weight 150,000) were mixed with water-methanol (50:50 volume ratio). ) Mixed with 50 g of a 15% solution dissolved in a mixed solvent,
A homogeneous dispersion was made using a paint shaker disperser. 150 μm thick polyethylene terephthalate (P
ET) Spraying the above dispersion at 150 μm intervals from top to bottom, left and right from an ink jet nozzle diameter of 100 μm onto the surface, and then heating the surface by infrared rays to fix the particles on the film to produce an under-sheet for lithographic printing did. When the size of the grains created on the film was observed with a microscope,
The average size was about 80 μm. The center line average roughness Ra of this surface was 25 μm.

Printing was performed in the same manner as in Example 1 except that the underlay sheet used in Example 1 was replaced with the underlay sheet prepared by the ink jet method. When the plate elongation of the printing plate after printing 2,000 sheets was measured in the same manner as in Example 1, it was 32 μm.

Example 4 20 g of clay (50% aqueous dispersion), 4 g of oxidized starch (20% aqueous solution), SBR latex (solid content 49%, Tg1)
0 ° C.) and 15 g of melamine resin precondensate (solid content 8
0%; 1 g of Sumiretz Resin SR-613) was dispersed with a Dynomill disperser for 15 minutes. This dispersion was sprayed onto a 150 μm-thick polyethylene terephthalate (PET) using an electrostatic spray gun, and then dried and fixed with an infrared heater to prepare a lithographic printing under sheet. When the size of the grains formed on the film was observed with a microscope, the average size was about 40 μm. The center line average roughness Ra of this surface was 5 μm.

Printing was carried out in exactly the same manner as in Example 1, except that the underlay sheet prepared in Example 1 was replaced with an underlay sheet prepared by the electrostatic spray method. When the plate elongation of the printing plate after printing 2,000 sheets was measured in the same manner as in Example 1, it was 27 μm.

Example 5 5 g of acrylic resin latex AE610 (c) (manufactured by Nippon Synthetic Rubber Co., Ltd.) was further mixed with water: methanol (90:10) on the treated surface of the underlay sheet prepared in Example 4. The solution stirred in 5 g of the liquid was applied as an overcoat layer with a wire bar so as to be ² g / m ² ,
For 5 minutes in an oven to prepare an underlay sheet for lithographic printing.

Printing was performed in exactly the same manner as in Example 4 except that this underlay sheet was used in place of the underlay sheet without an overcoat layer used in Example 4. When the plate elongation of the printing plate after printing 2,000 sheets was measured in the same manner as in Example 4, it was 28 μm. Further, when the surface of the underlay sheet after the printing was completed was observed in detail, the lack of convex grains on the underlay sheet surface used in Example 4 showed that the underlay sheet was 290 m thick.
Compared with the average under four microscopes within mx 400 mm, no dropout of particles was observed in the underlay sheet of Example 5 provided with the overcoat layer.

[0050]

By using the underlay sheet manufactured according to the present invention, the cost of the printing plate can be easily reduced, and the elongation of the printing plate can be effectively suppressed.

Claims (5)

[Claims] The present invention is characterized in that a material having an initial elastic modulus of 350 kgf / mm ² or more is adhered to at least one surface from the outside, and a projection having a dry height of 1 to 100 μm is provided. A method for producing an underlay sheet for planographic printing. 2. The lithographic printing plate-under-sheet according to claim 1, wherein the convex projections are obtained by attaching a material from the outside and further providing an overcoat layer on the entire surface thereof. Production method. 3. The convex projection has a center line average roughness Ra of 2
The method for producing a lithographic printing underlay sheet according to claim 1 or 2, wherein the thickness is from 20 to 20 µm. 4. The method according to claim 1, wherein the material contains a thermosetting compound. 5. The method according to claim 1, wherein the material contains a photocurable compound.