JPH09292703A - Laser direct waterless photosensitive planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high sensitivity, good image reproducibility, ink depositing property and excellent adaptability for printing with good balance of these properties by incorporating carbon black as a near infrared absorbent by a specified proportion to the whole solid component of a photosensitive layer and specifying the film thickness of the photosensitive layer. SOLUTION: This printing plate consists of a substrate on which a photosensitive layer containing at least a near infrared absorbent and a silicone rubber layer are successively formed in this order from the substrate. The proportion of the carbon black in the photosensitive layer is controlled to 40 to 98wt.% of the whole solid content of the photosensitive layer, preferably 50 to 98wt.% and more preferably 60 to 95wt.%. If the proportion of the carbon black is too small, the layer does not absorb laser rays enough so that the ablation efficiency easily decreases. If the proportion of the carbon black is higher than 98%, the film strength of the photosensitive layer decreases. The film thickness of the photosensitive layer is 0.3 to 5μm, preferably 0.3 to 3μm, and more preferably 0.5 to 2μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser direct dampening solution-free photosensitive lithographic printing plate capable of forming a printing plate directly from digital image data using a near-infrared semiconductor laser. More specifically, the present invention relates to a laser direct dampening solution-free photosensitive lithographic printing plate comprising a substrate and a photosensitive layer and a silicone rubber layer applied in this order.

[0002]

2. Description of the Related Art In recent years, with the progress of digital image processing technology using a near-infrared semiconductor laser and a computer, a photosensitive lithographic plate has been directly used from digital image data formed on a computer without using a silver halide film for a printing plate. The printing plate is subjected to scanning exposure with a near-infrared semiconductor laser to insolubilize the exposed portion, and then an image is formed by an aqueous solution development process (wet development process) to make a plate, or the exposed portion is deteriorated, sublimated, melted and removed. Laser direct plate making technology, in which an image is formed by performing a dry development process to make a plate, has attracted attention. In particular, there is no need to consider the balance between water and printing ink, the printing operation is easy, there is little wasted paper at the beginning of printing, and the printing time is short. It is expected as a new printing system because it can produce printed matter.

[0003] Various attempts have been made with respect to a laser-direct fountain-free photosensitive lithographic printing plate used in the fountain-free digital printing system.
(A) A photosensitive layer and a silicone rubber layer are applied in this order on a support, and the silicone rubber layer is simultaneously melted in response to heat generated by ablation of an exposed portion of the photosensitive layer.
Removed by volatilization or combustion (Japanese Patent Laid-Open No. 7-1
64773, 6-186750, 6-19906
(B) 7-309001), (b) those in which the silicone rubber layer is degraded in response to the heat generated by ablation of the exposed portion of the photosensitive layer, the adhesiveness to the support is reduced, and then the silicone rubber layer is scraped off. Kaihei 6-55723, 6-5586
9, 6-92050) and (c) a method of forming an ink-adhesive toner image on a support provided with a silicone rubber layer by an electrophotographic method (Japanese Patent Application Laid-Open No. 51-66008). I have. Among these methods, the method (a) is considered to be more preferable because the image forming process is the simplest and the image with the normal image quality is easily obtained.

However, a photosensitive lithographic printing plate that does not require a laser direct dampening solution using the above-described ablation requires a large number of high-power semiconductor lasers because of insufficient sensitivity in practice. Of the printing ink is low, or the printing resistance is low, and the printing suitability is not yet sufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a laser direct fountain solution having high sensitivity, good image reproducibility, good ink receptivity, and excellent printability due to their excellent balance. It is intended to provide an unnecessary photosensitive lithographic printing plate.

[0006]

The gist of the present invention is to provide a laser direct fountain solution-free photosensitivity having a photosensitive layer containing at least a near-infrared absorber and a silicone rubber layer on a substrate in this order. The lithographic printing plate contains 40 to 98% by weight of carbon black as a near-infrared absorber with respect to the total solid components of the photosensitive layer, and the film thickness of the photosensitive layer is 0.3 to 5 μm. It exists in a photosensitive lithographic printing plate that requires no laser direct dampening water.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As the substrate used in the present invention, any substrate can be used as long as it has flexibility that can be set in a normal lithographic printing machine and can withstand the load applied during printing, and is not particularly limited, including the layer configuration. . For example,
Examples include papers such as coated papers, metal plates such as aluminum plates, and plastic films such as polyethylene terephthalate. Of these, polyethylene terephthalate, an aluminum plate, or an aluminum foil and other composite materials are preferable, and the substrate is made of a metal such as aluminum or chromium for the purpose of enhancing the ablation effect of the photosensitive layer and the silicone rubber layer. Can be deposited or mirror-polished to provide a surface that reflects near-infrared light.

The thickness of the substrate is usually 10 μm to 1 mm, preferably 20 μm to 0.5 mm. The photosensitive layer used in the present invention efficiently absorbs near-infrared laser light and converts it into heat to ablate the photosensitive layer to remove the photosensitive layer, and at the same time, in response to the heat generated thereby, the silicone rubber layer The carbon black is contained as a near-infrared absorber having a function of inducing the ablation, melting, volatilizing or burning the ablation, and / or removing it by the pressure during the ablation of the photosensitive layer.

The carbon black is 680 to 1
It has a property of easily inducing ablation of the photosensitive layer by heat generated by absorption of laser light of near infrared light of 100 nm. The specific surface area of the carbon black measured by the nitrogen adsorption method is usually 150 m ² / g or less, preferably 130 m ² / g or less, more preferably 110 m ² / g or less. When the specific surface area is within the above range, the absorbance for near infrared laser light is high and the ablation efficiency of the photosensitive layer is high, which is preferable. 1st below
Specific examples are shown in the table, but the carbon black used in the present invention is not limited to these examples. still,
In Table 1, the values in parentheses represent the specific surface area (m ² / g) measured by the nitrogen adsorption method.

[0010]

[Table 1] Table 1 C-1 Mitsubishi Chemical Co., Ltd. MA220 (31) C-2 Mitsubishi Chemical Co., Ltd. MA230 (85) C-3 Mitsubishi Chemical Co., Ltd. # 3050 (50) C-4 Mitsubishi Chemical Co., Ltd. # 5 (25) C-5 Mitsubishi Chemical Corporation # 10 (28) C-6 Mitsubishi Chemical Corporation # 20 (56) C-7 Mitsubishi Chemical Corporation # 25 (55) C-8 Mitsubishi Chemical Corporation # 30 (85) ) C-9 Mitsubishi Chemical Co. # 32 (85) C-10 Mitsubishi Chemical Co. # 33 (93) C-11 Mitsubishi Chemical Co. # 40 (125) C-12 Mitsubishi Chemical Co. # 44 (125) C -13 Mitsubishi Chemical Corporation # 45 (125) C-14 Mitsubishi Chemical Corporation # 47 (130) C-15 Mitsubishi Chemical Corporation # 50 (103) C-16 Mitsubishi Chemical Corporation # 52 (113) C-17 Mitsubishi Chemical Corp. # 55 (103) C-18 produced by Mitsubishi Chemical Corporation CF9 (60 C-19 manufactured by Mitsubishi Chemical Corp. # 4000 (80) C-20 produced by Mitsubishi Chemical Corporation # 4010 (20) C-21 produced by Mitsubishi Chemical Corporation OIL30B (85) C-22 produced by Mitsubishi Chemical Corporation OIL31B (85) C-23 Mitsubishi Chemical company OIL11B (104) C-24 Mitsubishi Chemical company OIL913 (60) C-25 Mitsubishi Chemical company OIL7B (137) C-26 Mitsubishi Chemical company MA100 (134)

[0011]

[Table 2] Table 1 (continued) C-27 Mitsubishi Chemical MA11 (104) C-28 Mitsubishi Chemical MA8 (137) C-29 Mitsubishi Chemical MA7 (137) C-30 Colombian Carbon Co. Made Raven 1080 ULTRA (90) C-31 Colombian Carbon Co. Raven 1060 ULTRA (70) C-32 Colombian Carbon Co. Raven 1040 (95) C-33 Colombian Carbon Co. Raven 1035 (100) C-34 Colvenyan Carbon Co. Raven 1020 (95) C-35 Colombian Carbon Co. Raven 1000 (100) C-36 Colombian Carbon Co. Raven 890H (95) C-37 Colombian Carbon Co. Raven 890 (75) C -38 Koronbiyan carbon Co. Raven 850 (70) C-39 roller Biyan Carbon Co. Raven 790 ULTRA (70) C- 40 Koronbiyan Carbon Co. Raven 780 ULTRA (90) C- 41 Koronbiyan Carbon Co. Raven 760 ULTRA (70) C- 42 Koronbiyan Carbon Co. Raven 520 ( 45) C-43 Colombian Carbon Co. Raven 500 (48) C-44 Colombian Carbon Co. Raven 460 (38) C-45 Colombian Carbon Co. Raven 450 (33) C-46 Colombian Carbon Co. Raven 430 (34) C-47 Columbian Carbon Co. Raven 420 (29) C-48 Colombian Carbon Co. Raven 410 (27) C-49 Colombian Carbon Co. Raven 22 (23) C-50 Colombian Carbon Co. Made Raven 16 (27) C-51 Colombian Ka Carbon Raven 14 (50)

[0012]

[Table 3] Table 1 (continued) C-52 Asahi Carbon Asahi Thermal FT Class (24) C-53 Asahi Carbon Asahi # S500 Special Product (42) C-54 Asahi Carbon Asahi # 15 Special Product (12) C-55 Asahi Carbon Co., Ltd. Asahi # 35 N-754 (24) C-56 Asahi Carbon Co. Asahi # 50 N-762 (23)

The blending ratio of the carbon black in the photosensitive layer is 40 to 98% by weight, preferably 50 to 98% by weight, more preferably 60 to 9% by weight based on the total solid content of the photosensitive layer.
5% by weight. If the blending ratio of carbon black is extremely low, the laser beam cannot be sufficiently absorbed, so that the ablation efficiency is likely to decrease, and if the blending ratio of carbon black is higher than 98%, the film strength of the photosensitive layer is reduced, and printing Occasionally, there is a tendency to cause peeling of the silicone rubber layer and the photosensitive layer. In the photosensitive layer used in the present invention, in addition to the near-infrared absorber, coating properties, compatibility with the near-infrared absorber, film strength in the photosensitive layer, and enhance the effect of ablation For the purpose, organic polymeric substances can be added.

Examples of the organic polymer substance include unsaturated acids such as (meth) acrylic acid and itaconic acid, and (meth)
Alkyl acrylate, phenyl (meth) acrylate,
Copolymers of benzyl (meth) acrylate, styrene, α-methylstyrene and the like; alkyl methacrylate and alkyl acrylate polymers represented by polymethyl methacrylate; alkyl (meth) acrylate and acrylonitrile, vinyl chloride, Copolymers of vinylidene chloride, styrene, etc .; Copolymers of acrylonitrile with vinyl chloride or vinylidene chloride; Modified cellulose having a carboxyl group in the side chain; Polyethylene oxide; Polyvinylpyrrolidone; Phenol, o-, m-, p -Cresol, and / or
Or a novolak resin obtained by the condensation reaction of xylesol with aldehyde, acetone, etc .; polyether of epichlorohydrin with bisphenol A; soluble nylon; polyvinylidene chloride; chlorinated polyolefin; copolymer of vinyl chloride and vinyl acetate Vinyl acetate polymer; copolymer of acrylonitrile and styrene; copolymer of acrylonitrile, butadiene and styrene; polyvinyl alkyl ether; polyvinyl alkyl ketone; polystyrene; polyurethane; polyethylene terephthalate isophthalate; acetyl cellulose; Cellulose; acetylbutoxycellulose; nitrocellulose; celluloid; polyvinyl butyral and the like are used. The compounding ratio of the organic polymer substance in the photosensitive layer is 1 to 60% by weight, preferably 2 to 50% by weight, and more preferably 2 to 40% by weight based on the total solids of the photosensitive layer.

In the above-mentioned photosensitive layer, various additives having a hydrophobic group, such as p-octylphenol / formalin novolac resin, for the purpose of improving the ink receptivity of printing ink,
p-butylphenol / formalin novolak resin, p
-T-butylphenol-benzaldehyde resin, modified novolak resin such as rosin-modified novolak resin,
Further, o-naphthoquinonediazide sulfonic acid ester of these modified novolak resins, a fluorine-based surfactant is added, and for the purpose of enhancing the effect of abrasion, nitro compounds such as nitrocellulose having self-oxidation properties, sodium nitrate, ammonium nitrate, etc. Peroxides such as nitrates, benzoyl peroxide and perbenzoic acid esters, or azo compounds such as foamable azodicarbonamide and azobisisobutyronitrile; nitroso compounds such as N, N'-dinitropentamethylenetetramine; A sulfonyl hydrazide compound such as -toluenesulfonylhydrazine, p, p'-oxybis (benzenesulfohydrazine) or the like is used in an amount of 0.1 to 50% by weight, preferably 0.1 to 50% by weight, based on the total solid content of the photosensitive layer.
2 to 20% by weight, more preferably 0.5 to 10% by weight
It can be added and used.

The photosensitive layer of the present invention may contain fine particles having a low thermoconductivity of 5 μm or less, such as calcium carbonate, magnesium carbonate, zirconium oxide, and carion, for the purpose of improving the efficiency of ablation. In addition to the above-mentioned fine particles, fine particles of silicon oxide, titanium oxide or the like can be contained in order to increase the film strength of the above. The mixing ratio of the fine particles is 0 to 50% by weight of the total solids of the photosensitive layer,
Preferably it is 0 to 25% by weight. The film thickness of the photosensitive layer of the present invention is 0.3 to 5 μm, preferably 0.3 to 3 μm.
m, more preferably 0.5 to 2 μm. The transmission absorbance of the photosensitive layer at the wavelength of the laser beam is usually 0.3 or more, and preferably 0.5 or more, for the photosensitive layer having a thickness of 1 μm.

The silicone rubber layer used in the present invention is
It can be appropriately selected from known ones as described in the above-mentioned Japanese Patent Application Laid-Open No. 7-164773, etc., and described below, a condensation crosslinking type for curing the silicone rubber layer composition by a condensation reaction, and an addition reaction. Two types of addition-crosslinking type for curing the silicone rubber layer composition are preferably used.

The condensation-crosslinking type silicone rubber layer used in the present invention contains, as an essential component, a linear organopolysiloxane having hydroxyl groups at both ends and a reactive silane compound which is crosslinked with the organopolysiloxane to form a silicone rubber layer. It includes. Examples of the linear organopolysiloxane having a hydroxyl group at both terminals used in the present invention include a linear organopolysiloxane represented by the following general formula (I).

[0019]

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(In the formula, two R ^1's each independently represent a hydrogen atom, a methyl group, a phenyl group or a vinyl group, and y is 1
The following integers are shown. Of the compounds represented by formula (I), those in which R ¹ is a methyl group are preferred. The weight average molecular weight (hereinafter, abbreviated as Mw) of the organopolysiloxane is from 5,000 to
1,000,000, preferably 10,000 to
1,000,000. If the Mw is extremely low, the film strength of the silicone rubber layer will be reduced, and the printing resistance will be reduced. If the Mw is extremely high, the effect of removing the silicone rubber layer by ablation will be reduced, resulting in reduced sensitivity and reduced image reproducibility. Cheap.

Further, the reactive silane compound used in the present invention reacts with the hydroxyl groups of the linear organopolysiloxane having hydroxyl groups at both ends, and is deacetic acid type, deoxime type, dealcohol type, deamino type or It is a reactive silane compound having a molecular weight of 2,000 or less, which has at least two functional groups capable of undergoing condensation such as dehydration type crosslinking. Specific examples of the functional group include functional groups represented by the following formulas.

[0022]

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(In the formula, R ² represents an alkyl group having 1 to 5 carbon atoms, but when ^two R ² are present in the same atomic group, they may be the same or different.) Of these, functional Group is an acyloxy group (-OCO
R ² ) having three or more functional groups, or a functional group having an alkoxy group (—OR ² ) having three or more functional groups,
It is preferable to form a silicone rubber layer in a short time after the drying treatment after the application. More preferably, the functional group is an acetoxy group and the number of functional groups is 3 or more, or the functional group is an alkoxy group and the number of functional groups is 6 or more.

Examples of the reactive silane compound include compounds represented by the following general formulas (II) to (V). In the formula, Q represents a group selected from the functional groups which react with the hydroxyl groups of the above-mentioned linear organopolysiloxane having hydroxyl groups at both ends, and Q has at least two in one molecule.

[0025]

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(In the formula, X is an alkyl group having 1 to 5 carbon atoms,
Phenyl group, vinyl _{group, H 2 N- (CH 2)} h -, CH
₂ ＣC (CH ₃ ) CO—, CH ₂ ＣＨCHCO—,

[0027]

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And R ² has 1 to 5 carbon atoms as described above.
R ³ represents an allyl group or — (CH ₂ )
It indicates _{^{q -SiR 2 3-p Q p}} , R 4 is a hydrogen atom, a carbon number 1
5 alkyl group, or a phenyl group, R ^2, R
^When each of ³ and R ⁴ is present in a plurality in the same molecule,
Each of the plurality may be the same or different,
h, j and q each represent an integer of 1 to 5, p and r each represent an integer of 1 to 3, s represents an integer of 2 to 4, t and u each represent an integer of 0 to 5 . Table 2 shows more specific examples of the reactive silane compound used in the present invention, but the present invention is not limited to these examples.

[0029]

[Table 4]

[0030]

[Table 5]

[0031]

[Table 6]

The condensation-crosslinking type silicone rubber layer used in the present invention contains an organic carboxylic acid, titanium in order to enhance the reaction efficiency of the condensation-crosslinking reaction between the organopolysiloxane having hydroxyl groups at both ends and the reactive silane compound. A condensation catalyst such as an acid ester, a stannate ester, an aluminum organic ether, and a platinum-based catalyst is appropriately mixed and a condensation reaction is performed to cure.

The blending ratio of the organopolysiloxane having hydroxyl groups at both terminals used in the present invention, the reactive silane compound and the condensation catalyst in the silicone rubber layer is such that the hydroxyl groups at both terminals are relative to the solid content of the entire silicone rubber layer. The organopolysiloxane has 80 to 98% by weight, preferably 85 to 98% by weight, and the reactive silane compound is usually 2 to
20% by weight, preferably 2 to 15% by weight, more preferably 2 to 7% by weight, and the condensation catalyst is 0.05 to 5% by weight, preferably 0.1 to 3% by weight, more preferably 0.1 to 3% by weight.
1% by weight.

When the proportion of the reactive silane compound or the condensation catalyst is extremely high, the ink repulsion property is lowered, and it becomes difficult to remove the silicone rubber layer during ablation.
Sensitivity and image reproducibility decrease. On the other hand, when it is extremely low, the film strength of the silicone rubber layer is reduced, and the printing durability is reduced.

In the condensation-crosslinking type silicone rubber layer used in the present invention, polysiloxanes other than the polyorganosiloxane having hydroxyl groups at both ends described above are added to the silicone rubber layer in order to enhance the ink resilience of the silicone rubber layer. 2 to 15% by weight, preferably 3 to 12 based on the solid content
% By weight. As the polysiloxane, for example, Mw1 in which both terminals are trimethylsilylated
And a polydimethylsiloxane of 000 to 1,000,000.

Next, the addition-crosslinking type silicone rubber layer used in the present invention comprises an organopolysiloxane having at least two aliphatic unsaturated groups in one molecule and a silicone rubber layer crosslinked with the organopolysiloxane. An organopolysiloxane having at least two Si—H bonds in one molecule to be formed is contained as an essential component.

The organopolysiloxane having at least two aliphatic unsaturated groups in one molecule used in the present invention may have a chain structure, a cyclic structure or a branched structure, but a chain structure is preferred. Examples of the aliphatic unsaturated group include alkenyl groups such as vinyl group, allyl group, butenyl group, pentenyl group and hexenyl group; cycloalkenyl groups such as cyclopentenyl group, cyclohexenyl group, cycloheptenyl group and cyclooctenyl group; ethynyl group And alkynyl groups such as propynyl group, butynyl group, pentynyl group and hexynyl group. Among these, an alkenyl group having an unsaturated bond at a terminal is preferable from the viewpoint of reactivity,
Vinyl groups are particularly preferred. The remaining substituents other than the aliphatic unsaturated groups are preferably methyl groups in order to obtain good printing ink repellency.

At least 2 aliphatic unsaturated groups are contained in one molecule.
Mw of the organopolysiloxane having a number of
500,000, preferably 1,000 to 3.0
00,000. When the Mw is extremely low, the strength of the silicone rubber layer is reduced, the silicone rubber layer is easily damaged at the time of printing, and the printing ink repellency of the portion is reduced,
Ink easily adheres, causing printing stains. Further, when Mw is extremely high, the removal of the silicone rubber layer by ablation becomes poor, which tends to cause a decrease in sensitivity and a decrease in image reproducibility.

The organopolysiloxane having at least two Si--H bonds in one molecule used in the present invention is
The structure may be chain, cyclic, or branched,
A chain is preferred. The Si-H bond may be at the terminal or the middle of the siloxane skeleton, and the ratio of hydrogen atoms to the total number of substituents is usually 1 to 60%, preferably 2 to 50%. The remaining substituents other than hydrogen atoms are preferably methyl groups in order to obtain good printing ink repellency. The Mw of an organopolysiloxane having at least two Si—H bonds in one molecule is usually 3
00 to 300,000, preferably 500 to 20
It is 0000. If the Mw is extremely high, the sensitivity and the image reproducibility tend to decrease.

The above-mentioned organopolysiloxane having at least two aliphatic unsaturated groups in one molecule and S in one molecule.
In order to carry out the addition reaction of the organopolysiloxane having at least two i-H bonds, an addition reaction catalyst is usually used. The addition reaction catalyst can be arbitrarily selected from known catalysts, but a platinum-based catalyst is preferable, and one or a mixture of two or more selected from platinum group metals and platinum group compounds is used. Examples of the platinum group metal include a simple substance of platinum (for example, platinum black), a simple substance of palladium (for example, palladium black), and a simple substance of rhodium. Examples of the platinum group compounds include chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum-ketone complexes, complexes of platinum and vinylsiloxane, tetrakis (triphenylphosphine) platinum, tetrakis (triphenylphosphine) palladium and the like. Is exemplified. Among these, chloroplatinic acid or a platinum-olefin complex is used as an alcohol-based solvent,
A solvent dissolved in a ketone solvent, an ether solvent, a hydrocarbon solvent or the like is particularly preferable.

The compounding ratio of each composition forming the silicone rubber layer described above is such that the organopolysiloxane having at least two aliphatic unsaturated groups in one molecule is 80 with respect to the total solid content of the silicone rubber layer. % To 98% by weight, preferably 85 to 98% by weight, and the organopolysiloxane having at least two Si—H bonds in one molecule is 2
-20% by weight, preferably 2-15% by weight, and the addition reaction catalyst is 0.00001-10% by weight, preferably 0.0001-5% by weight.

When the compounding ratio of the organopolysiloxane having at least two Si--H bonds in one molecule is extremely low, the film strength of the silicone rubber layer is lowered, the repulsion of the printing ink and the printing resistance are lowered, and the compounding ratio is lowered. When it is extremely high, the sensitivity and the image reproducibility are deteriorated. In addition, in addition to the above composition, the addition-crosslinking type silicone rubber layer used in the present invention, for the purpose of further increasing the film strength of the silicone rubber layer,
An amino-based organosilicon compound having a hydrolyzable group represented by the following general formula (VII) can be added.

[0043]

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(In the formula (VI), Z represents a hydrolyzable group,
R ⁵ represents a divalent hydrocarbon group; R ⁶ represents a monovalent optionally substituted hydrocarbon group; and two R ^{7 s} each independently represent a hydrogen atom or a monovalent substituted group. a group represented by the good hydrocarbon group or _{^{-R 5 -SiR 6 3-p Z}} p, p is an integer of 1-3. )

Examples of the hydrolyzable group represented by Z include alkoxy groups such as methoxy group, ethoxy group and propoxy group; alkenyloxy groups such as 2-propenyloxy group; aryloxy groups such as phenoxy group; acetyloxy. And an acyloxy group such as a group. Among these, a methoxy group, an ethoxy group, and an acetyloxy group are preferred in terms of stability, curability, and the like. Examples of the divalent hydrocarbon group for R ⁵ include:

[0046]

[Chemical 6]

Is preferred. Examples of the monovalent hydrocarbon group which may be substituted among the substituents represented by R ⁶ and R ⁷ include, for example, alkyl groups such as methyl group, ethyl group, propyl group and butyl group; cyclopropyl group, cyclobutyl Group,
Cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group such as cyclooctyl group; vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, etc. alkenyl group; cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, Cycloalkenyl groups such as cyclooctenyl group; substituted alkyl groups such as glycidoxypropyl group, acryloxypropyl group, methacryloxypropyl group and aminoethyl group. From the viewpoint of curability, R ⁶ and R ⁷ are preferably a vinyl group, an allyl group, a glycidyl group, a methacryl group, or a γ-glycidoxypropyl group.

Specific examples of the amino type silicon compound include 3- [N-allyl-N- (2-aminoethyl)] aminopropyltrimethoxysilane and 3- (N-
Allyl-N-glycidyl) aminopropyltrimethoxysilane, 3- (N-allyl-N-methacryl) aminopropyltrimethoxysilane, N-glycidyl-N, N-
Bis [3- (methyldimethoxysilyl) propyl] amine, N-glycidyl-N, N-bis [3- (trimethoxysilyl) propyl] amine, aminopropyltrimethoxysilane, aminopropyltriacetyloxysilane, 3- [ N-allyl-N- (2-aminoethyl)] aminopropyltriacetyloxysilane, 3- (N-allyl-N-glycidyl) aminopropyltriacetyloxysilane, 3- (N-allyl-N-methacryl) amino Examples include propyltriacetyloxysilane and the like.
These may be used as a mixture of two or more.

The amino type organosilicon compound is 0 to 10% by weight, preferably 0 to 5% by weight based on the total solid content of the silicone rubber layer. In addition, a curing retarder can be added to the addition-crosslinking type silicone rubber layer used in the present invention in order to prevent rapid curing of the silicone layer composition when the silicone rubber layer is applied. The curing retarder can be arbitrarily selected from commonly known acetylenic alcohols, maleic esters, silylated acetylenic alcohols, silylated maleic acids, triallyl isocyanurate, vinyl siloxane, and the like.

The amount of the curing retarder added varies depending on the desired curing rate, but is usually 0.0001 to 1.0 part by weight based on the total solid content of the silicone rubber layer. The condensation-crosslinking type and addition-crosslinking type silicone rubber layers used in the present invention may be added with an inorganic filler such as silica, titanium oxide, and aluminum oxide for the purpose of improving the strength. Is preferably used. As such a filler, those having an average particle diameter of 500 μm or less are preferred from the viewpoint of dispersibility or dispersion stability.

These silicone rubber layers are excellent in printing ink repulsion and printing resistance, and are easily removed by ablation, and have a function of giving high sensitivity and high image reproducibility. The silicone rubber layer has a scratch strength of 10 to 1
It is preferably 00 g. However, the scratch strength means the weight (g) required to generate a scratch when a 0.2 mm sapphire needle is moved at a speed of 10 cm / min while applying a load on the printing plate. Represent. When the scratch strength is in the above range, printability such as repellency, printing resistance, sensitivity, and image reproducibility of the printing ink becomes good. The thickness of the silicone rubber layer used in the present invention is 0.1 to 10
μm, preferably 0.2 to 5 μm, more preferably 0.3 to 2 μm.

The photosensitive layer composition and the silicone rubber layer composition described above are dissolved in a suitable solvent to form a solution,
After applying this on the substrate by various coating devices such as a wire bar, a spinner and a roll coater on the support,
After drying, a photosensitive layer and a silicone rubber layer can be respectively formed. Examples of the coating solvent for the photosensitive layer include ketones such as methyl ethyl ketone and cyclohexanone; esters such as butyl acetate, amyl acetate and ethyl propionate; and hydrocarbons such as toluene, xylene, monochlorobenzene, carbon tetrachloride, trichloroethylene, and trichloroethane. And halogenated hydrocarbons, methylcellosolve, ethylcellosolve, ethers such as tetrahydrofuran, and further, propylene glycol monomethyl ether acetate, bentoxone, dimethylformamide and the like can be used in common use.As a coating solvent for the silicone rubber layer, n-hexane, cyclohexane,
Petroleum ether, aliphatic hydrocarbon solvent Exxon Chemical Co., Ltd .: Isopar E, H, G, and a mixed solvent of these solvents and the above-mentioned photosensitive layer coating solvent can be used.

If necessary, for the purpose of protecting the silicone rubber layer, various releasable plastic sheets such as polypropylene sheet, polyethylene sheet, release treated polyethylene terephthalate, release treated paper, aluminum, iron,
It can be provided by laminating a metal sheet such as copper on the silicone rubber layer. The photosensitive printing plate provided with the photosensitive layer and the silicone rubber layer on the substrate is usually 680 to 680.
A semiconductor laser beam that oscillates near-infrared light of 1100 nm is subjected to scanning exposure with a beam spot focused to a diameter of 5 to 30 μm to ablate the exposed portion, and then used as a printing plate without post-treatment. Brushes, pads, ultrasonic waves while supplying an aqueous solution or an organic solvent to the surface of the silicone rubber layer for the purpose of removing fine particles of the photosensitive layer or the silicone rubber layer generated by ablation adhered on the exposed printing plate. Alternatively, a post-treatment such as spraying to give a physical stimulus may be performed.

As another method for removing the fine particles generated by the ablation, a silicone rubber layer of a photosensitive printing plate which has been exposed to a cover sheet having a surface having a higher adhesiveness to the fine particles than the silicone rubber layer is used. After laminating so that the surface of the silicone rubber and the surface of the adhesive cover sheet fit together, a method of peeling or before exposure,
A method of laminating a cover sheet, which is a cover sheet that transmits a laser beam, in the same manner as described above, peeling after exposure, and removing fine particles on the silicone rubber layer can be mentioned.
Examples of the cover sheet include a base plate made of polyethylene terephthalate, polypropylene, polycarbonate, paper, and the like, on which an adhesive layer made of silicone rubber, ionomer, vinyl acetate, or the like is provided as necessary.

[0055]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples. Examples 1 to 11 and Comparative Examples 1 to 3 On art paper having a thickness of 100 μm, a thickness of 35 μm and a density of 1.
A photosensitive layer composition having the following composition was applied onto a composite substrate laminated with a 2 g / cm ³ expanded polyethylene terephthalate sheet. [Photosensitive Layer Composition] Near-infrared absorber: carbon black described in Table 3 blending amount described in Table 3 organic polymer substance:

[0056]

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A polymer having Mw = 10000 containing the above-mentioned units represented by the following in a molar ratio of a: b: c: d≈55: 20: 10 30 parts by weight Coating solvent: cyclohexanone 600 parts by weight dichloroethane 100 parts by weight 100 parts by weight of ethanol was applied and dried at 85 ° C. for 3 minutes to form a photosensitive layer having a dry film thickness of 1 μm. Subsequently, a silicone rubber layer composition having the following composition was applied on the photosensitive layer.

[Silicone rubber layer composition] Polydimethylsiloxane having hydroxyl groups at both ends: The following compound (y represents an integer of 1 or more).

[0059]

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Reactive silane compound: Compound described in Table 3 Compounding amount described in Table 3 Condensation catalyst: Cibutyltin dilaurate 0.8 part by weight Coating solvent: Isopar E (manufactured by Exxon Chemical Co.) 900 parts by weight After coating After drying at 100 ° C. for 4 minutes, a silicone rubber layer having a dry film thickness of 1 μm was provided to prepare a photosensitive sample.

The photosensitive sample was fixed on a rotating drum having a circumference of 20 cm so that the silicone rubber layer was on the outside, and the drum was rotated. Next, 830 is placed on the rotating sample.
nm, 30mW semiconductor laser light (Hitachi, Ltd.,
HL8325G) was condensed to a beam diameter of 15 μm, and scanning exposure was performed. Subsequently, the following items were evaluated. Table 3 shows the results.

[Absorbance] The photosensitive layer composition was dried on a polyethylene terephthalate film having a thickness of 100 μm to give a dry film thickness of 1 μm.
And was dried at 80 ° C. for 3 minutes to prepare a photosensitive layer sample. The absorbance of the sample at 830 nm was measured by a spectrophotometer U-3400 manufactured by Hitachi, Ltd. It is to be noted that the values in Table 3 having an absorbance of 4 or more are certainly 4 or more, but specific numerical values could not be measured.

[Sensitivity] While rotating the rotating drum at various rotational speeds, the sample was exposed by scanning, and then the sample was exposed to 400
Observed with a double microscope, the silicone rubber layer in the laser exposed area is removed by the minimum scanning speed (cm / min),
The sensitivity was evaluated. The higher the scanning speed, the higher the sensitivity.

[Ink inking property] A sample having a fine line image with a width of 15 μm formed by scanning exposure with a laser beam at the minimum scanning speed was used to print a printing ink for a lithographic printing plate that does not require dampening water (Aqualess echo red manufactured by Toyo Ink Co., Ltd.). ) Is kneaded with a rubber roller having a diameter of 7 cm, and the roller on which the ink is in contact with the silicone rubber layer of the sample is reciprocally moved on the sample to perform ink buildup. Ink temporarily attached to the line part was gradually removed by the reciprocation of the roller, and a sample when the ink was completely removed was used, and Mitsubishi Tokubishi Art Paper (manufactured by Mitsubishi Paper Mills) was used on the sample. the was laminated with 2kg / cm ^2, 60cm / min to overlap and the coated surface of the silicone rubber layer and the art paper samples were peeled off the art paper, which is formed on art paper thin line Than link image, we were evaluated for ink receptivity.

A: A continuous fine line image of 95% or more is reproduced on the art paper. B: Fine line image portion of more than 5% and 20% or less is not transferred on the art paper, and a broken fine line image is reproduced. . C: Fine line image portions exceeding 20% and 40% or less were not transferred onto the art paper, and intermittent fine line images were reproduced. D: Fine line image portions exceeding 40% were not transferred onto the art paper, and intermittent fine line images were reproduced.

[0066]

[Table 7]

Example 12 A photosensitive sample was prepared in the same manner as in Example 1 except that the silicone rubber layer composition was changed to the following, and the same evaluation was performed. As a result, sensitivity (60m /
s) and the ink inking property (A) was obtained.

[Silicone Rubber Layer Composition] Organopolysiloxane having at least two aliphatic unsaturated groups in one molecule: α, ω-divinylpolydimethylsiloxane (Mw = 12,000) 100 parts by weight In one molecule Organopolysiloxane having at least two Si—H bonds: α, ω-dimethylpolysiloxane below

[0069]

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(Approximately 40% of the substituents R in the formula are hydrogen atoms, the remaining approximately 60% are methyl groups, and y represents an integer of 1 or more, Mw = 2,000) 7 wt. Part Addition reaction catalyst: complex of chloroplatinic acid and vinyl siloxane 0.1 part by weight Curing retarder: compound of the following formula

[0071]

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Coating solvent: Isopar E (manufactured by Exxon Chemical Co.) 900 parts by weight

Example 13 A sample was prepared and evaluated in the same manner as in Example 1 except that the substrate was changed to a polyethylene terephthalate sheet having a thickness of 100 μm. as a result,
The sensitivity (30 m / s) and the ink receptivity (B) were obtained.

[0074]

According to the present invention, it is possible to provide a photosensitive lithographic printing plate which is excellent in sensitivity, image reproducibility and ink depositing property, and does not require a fountain solution.

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[Procedure amendment]

[Submission date] March 10, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction contents]

[Sensitivity] The sample was scanned and exposed while rotating the rotary drum at various rotational speeds, and then the sample was observed with a microscope of 400 times, and the maximum scanning for removing the silicone rubber layer in the laser-exposed portion was performed. The sensitivity was evaluated by the speed (cm / s). The higher the scanning speed, the higher the sensitivity.

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Claims (6)

[Claims] 1. A near-infrared absorber in a photosensitive lithographic printing plate which does not require a laser direct dampening water and has a photosensitive layer containing at least a near-infrared absorber and a silicone rubber layer on the substrate in this order. As a laser direct dampening water, characterized by containing 40 to 98% by weight of carbon black with respect to the total solid components of the photosensitive layer and having a film thickness of 0.3 to 5 μm. Photosensitive lithographic printing plate. 2. The transmission absorbance of the photosensitive layer at a near infrared laser wavelength is 0. 0 for a film thickness of 1 μm of the photosensitive layer.
5. The photosensitive lithographic printing plate not requiring a laser direct fountain solution according to claim 1, which is 5 or more. 3. The photosensitive lithographic printing plate not requiring a laser direct fountain solution according to claim 1, wherein the specific surface area of the carbon black measured by the nitrogen absorption method is 150 m ² / g or less. 4. The laser direct dampening according to claim 1, wherein the silicone rubber layer contains a linear organopolysiloxane having hydroxyl groups at both ends and a reactive silane compound. A water-free photosensitive lithographic printing plate. 5. The silicone rubber layer contains an organopolysiloxane having at least two aliphatic unsaturated groups in one molecule and an organopolysiloxane having at least two Si—H bonds in one molecule. 4. A photosensitive lithographic printing plate which does not require a laser direct fountain solution according to claim 1, wherein 6. The scratch resistance of the silicone rubber layer is 1
The photosensitive lithographic printing plate not requiring a laser direct fountain solution according to claim 1, which is 0 to 100 g.