JPH10186636A - Laser-direct waterless photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser-direct waterless photosensitive lithographic printing plate having excellent ink repelling property and reproducibility of images under high printing pressure and high temp. printing conditions or under printing conditions for lots of sheets. SOLUTION: This laser-direct waterless photosensitive lithographic printing plate consists of a substrate and a photosensitive layer containing at least an absorbent for near IR rays and a silicone rubber layer formed on the substrate in this order. The silicone rubber layer contains (a) linear organopolysiloxane having hydroxyl groups on both molecular ends by not less than 60wt.% nor more than 98wt.% of the whole solid content of the silicone rubber layer, (b) reactive silane compd. by not less than 1wt.% nor more than 20wt.% of the whole solid content of the silicone rubber layer and (c) organopolysiloxane having at least two Si-H bonds in one molecule by not less than 0.1wt.% nor more than 20wt.% of the whole solid content of the silicone rubber layer.

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 form an image by aqueous solution development (wet development) to form a plate, or to deteriorate, sublimate, melt, and remove the exposed portion. 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 which does not require laser dampening water using the ablation method of the above-mentioned method (a) maintains good printing ink repellency and printing durability (durability) of the silicone rubber layer. At the same time, the silicone rubber layer must be removable at the time of ablation. Therefore, if the thickness of the silicone rubber layer is increased to improve the print resistance and the strength of the silicone rubber layer is improved, the printability such as sensitivity and image reproducibility tends to decrease, which is a problem.

[0005]

SUMMARY OF THE INVENTION The present invention aims to provide a laser direct dampening solution-free photosensitive lithographic printing plate having high sensitivity, high image reproducibility, and excellent printing ink repellency and printing resistance of a silicone rubber layer. Is what you do.

[0006]

That is, the gist of the present invention is as follows.
In a laser-direct fountain-free photosensitive lithographic printing plate having, in this order, a photosensitive layer containing at least a near-infrared absorber from the substrate and a silicone rubber layer on the substrate, the silicone rubber layer comprises (a) 60% by weight or more and less than 98% by weight, based on the total solid content of the silicone rubber layer, of a linear organopolysiloxane having hydroxyl groups at both ends,
(B) 1% by weight or more and less than 20% by weight of the reactive silane compound based on the total solid content of the silicone rubber layer, and (c) 0.1% by weight or more and 20% or more based on the total solid content of the silicone rubber layer.
At least 2% by weight of Si—H bonds in one molecule.
The present invention relates to a photosensitive lithographic printing plate requiring no laser dampening solution, which comprises an organopolysiloxane having a plurality of organopolysiloxanes.

[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 paper (resin-processed paper and synthetic paper), metal plates such as aluminum plates, and plastic films such as polyethylene terephthalate. Among these, specific examples of preferable substrates include, for example, synthetic paper, resin-treated paper, polyethylene terephthalate sheet, aluminum plate of 50 μm to 500 μm, or 20 to 100 μm polyethylene terephthalate sheet, foamed polyethylene terephthalate sheet, polypropylene Examples include a sheet, a foamed polypropylene sheet, a polyethylene sheet, or a composite substrate obtained by laminating a foamed polyethylene sheet. Further, on the back surface of the composite substrate, as a reinforcing layer,
What laminated | stacked the aluminum plate of 0 micrometer is mentioned.

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, converts it into heat, causes ablation of the photosensitive layer and removes the photosensitive layer, and at the same time, responds to the heat generated by the silicone rubber layer. Contains a near-infrared absorbing agent having a function of inducing ablation, melting, volatilizing or burning, and / or removing the photosensitive layer by pressure during ablation.

The near-infrared absorbing agent can be used without any particular limitation as long as it has a function of absorbing near-infrared light and converting light energy into heat energy. And inorganic pigments, organic pigments, metals and the like. More specifically, for example, carbon black (MA-7, MA-1 manufactured by Mitsubishi Chemical Corporation)
00, MA-220, # 5, # 10, color black FW2, FW20, Printex V, etc., products of Degussa; graphite; metals such as titanium and chromium; titanium oxide (manufactured by Mitsubishi Materials Corporation, titanium black 13M) etc),
Metal oxides such as tin oxide, zinc oxide, vanadium oxide, and tungsten oxide; metal carbides such as titanium carbide;
Metal borides: Organic pigments such as black and green such as inorganic black pigments, azo black pigments, lionol green 2YS, and green pigments 7 described in JP-A-4-322219 are used. In addition, "special functional dyes" (Ikemori
Edited by Sumitani, published by CMC in 1986), "Chemicals of Functional Dyes" (edited by Higaki, published by CMC in 1981), "Dye Handbook" (edited by Okawa, Hirashima, Matsuoka, Kitao, published by Kodansha ), Catalog published by Japan Photographic Dye Laboratories, Inc. in 1995 and Exciton
Inc. And dyes having absorption in the near-infrared region described in Laser Dye Catalog published in 1989. Further, JP-A-3-97590 and JP-A-9759
Organic dyes having absorption in the near-infrared region described in JP-A-2-2074, JP-A-2075, JP-A-2076 and the like, and near-infrared rays such as IR820B manufactured by Nippon Kayaku Co., Ltd. Dyes having absorption in the region are also used. Some of such dyes having absorption in the near infrared region are exemplified in Table 1 below.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

[0015]

[Table 6]

[0016]

[Table 7]

[0017]

[Table 8]

[0018]

[Table 9]

[0019]

Table 10 S-34 polymethine dye; IR-820B (manufactured by Nippon Kayaku Co., Ltd.) S-35 nigrosine dye; Color Index Solvent Black
5 S-36 Nigrosine dye; Color Index Solvent Black
7 S-37 nigrosine dye; Color Index Acid Black 2 S-38 carbon black; MA-100 (manufactured by Mitsubishi Chemical Corporation) S-39 titanium monoxide; titanium black 13M (manufactured by Mitsubishi Materials Corporation) S-40 titanium monoxide; Titanium black 13B (Mitsubishi Materials Corporation)

[0020]

[Table 11]

[0021]

[Table 12]

These light absorbers can be used alone or as a mixture of two or more, dissolved or dispersed in a photosensitive layer coating solution, and used. When compounding the near-infrared absorber, the compounding ratio in the photosensitive layer is 5 to 5% of the solid content of the entire photosensitive layer.
It is 100% by weight, preferably 10 to 98% by weight, more preferably 20 to 95% by weight. Alternatively, the near infrared absorbing agent may be directly deposited on a substrate by vapor deposition or the like to provide a photosensitive layer composed of the near infrared absorbing agent. In this case, the film thickness is 0.01 to 0.5 μm, preferably 0.02 to 0.4 μm.
m. In the photosensitive layer used in the present invention, in addition to the near-infrared absorber, coating properties, compatibility with the near-infrared absorber,
An organic polymer substance can be added for the purpose of increasing the strength of the film in the photosensitive layer and the effect of ablation.

Examples of the organic polymer include unsaturated acids such as (meth) acrylic acid and itaconic acid;
Alkyl acrylate, phenyl (meth) acrylate,
Copolymers with (meth) acrylates such as benzyl (meth) acrylate, styrene, α-methylstyrene and the like are used. A modified cellulose having a carboxyl group in the side chain; polyethylene oxide; polyvinylpyrrolidone; phenol, o-, m-, p-cresol;
Novolak resin obtained by condensation reaction of xylesol with aldehyde, acetone, etc .; polyether of epichlorohydrin with bisphenol A; soluble nylon; alkyl methacrylate or alkyl acrylate polymer represented by polymethyl methacrylate; methacryl Copolymer of alkyl acrylate and acrylonitrile, acrylic acid, methacrylic acid, vinyl chloride, vinylidene chloride, styrene, etc .; copolymer of acrylonitrile with vinyl chloride or vinylidene chloride; polyvinylidene chloride; chlorinated polyolefin; vinyl chloride and acetic acid Copolymer of vinyl; polymer of vinyl acetate; copolymer of acrylonitrile and styrene; copolymer of acrylonitrile with butadiene and styrene; polyvinyl alkyl ether; polyvinyl alkyl ketone; Polyurethane, polyethylene terephthalate isophthalate; acetylcellulose; acetyl prop oxy cellulose; acetyl butoxy cellulose; nitrocellulose; celluloid, polyvinyl butyral or the like is used. The compounding ratio of the organic polymer substance in the photosensitive layer is from 0 to 95% by weight of the total solid content of the photosensitive layer,
It is preferably 2-90% by weight, more preferably 5-80% by weight.
% By weight.

In the photosensitive layer, various additives having a hydrophobic group, for example, p-octylphenol / formalin novolak resin, for the purpose of enhancing the adhesion 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 thickness of the photosensitive layer used in the present invention is 0.05 to 10 μm, preferably 0.1 to 5 μm, and more preferably 0.3 to 2 μm.

Next, the silicone rubber layer used in the present invention comprises a linear organopolysiloxane having a hydroxyl group at both terminals, a reactive silane compound which forms a silicone rubber layer by crosslinking with the organopolysiloxane, and Si in one molecule. And an organopolysiloxane having at least two -H bonds as an essential component. The silicone rubber layer has excellent printing ink repellency and printing resistance, is easily removed by ablation, and has high sensitivity and high image quality. Has the function of giving reproducibility. 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 (IV).

[0026]

Embedded image

(Wherein R ¹ and R ² are each a hydrogen atom,
It represents a methyl group, a phenyl group, or a vinyl group, and y represents an integer of 1 or more. R ¹ and R ^{2 of the} compounds represented by the above general formula (IV)
Is preferably a methyl group. The weight average molecular weight (hereinafter abbreviated as Mw) of the organopolysiloxane is 500
0 to 3,000,000, preferably 50,000 to 2
000000, more preferably 500,000 to 200
0000. 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.

The reactive silane compound used in the present invention reacts with the hydroxyl group of the linear organopolysiloxane having a hydroxyl group at both ends to form a deacetic acid type, a deoxime type, a dealcohol type, a deamino type or It is a reactive silane compound having a molecular weight of 2000 or less and having at least two functional groups capable of causing cross-linking by condensation such as dehydration type. Specific examples of the functional group include functional groups represented by the following formulas.

[0029]

Embedded image

(Wherein, R ^{3 to} R ¹⁰ each represent a hydrogen atom or an alkyl group. The alkyl group usually has 1 to 5 carbon atoms.) Of these, the functional group is an acyloxy group (- OCO
R ³ ) having three or more functional groups, or a functional group having an alkoxy group (—OR ⁸ ) 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. Specific examples of the reactive silane compound include compounds represented by general formulas (V) to (VIII).

[0031]

Embedded image

(In the formula (V), R¹¹Is-(CH_Two)_n-S
iR¹⁴ _3-mX_mAnd R¹²And R ¹³Is R¹¹
Is the same as or -CH_TwoCH = CH_TwoIs shown. Ma
M represents an integer of 1 to 3, and n represents an integer of 1 to 5.
Then R¹⁴Is an alkyl group having 1 to 5 carbon atoms or a phenyl group
And X is

[0033]

Embedded image

Is shown. (However, R^Three~ R^TenIs before each
Indicates the same as above. )) In the compound represented by the formula (V), X represents an acetoxy group,
A methoxy group or an ethoxy group is preferred, and
M is 2 or 3;¹¹, R¹²And R ¹³Is -C
H_TwoCH_TwoCH_TwoSi (OCH_Three)_ThreeOr -CH_TwoC
H_TwoCH_TwoSi (OC_TwoH_Five)_ThreeIs more preferred
New

[0035]

Embedded image

And k and j each represent an integer of 1 to 5. P represents an integer of 1 to 3, and R ¹⁴ , X, m
And n each represent the same as in the case of the general formula (V). In the compound represented by the formula (VI), X is an acetoxy group,
Those which are methoxy or ethoxy groups are preferred, and those in which m and n are 2 or 3 and X is a methoxy or ethoxy group are more preferred.

[0037]

Embedded image Z _4-q —Si—X _q (VII)

(In the formula (VII), Z is an alkyl group having 1 to 5 carbon atoms, a phenyl group, a vinyl group, or

[0039]

Embedded image

And q represents an integer of 1 to 4. Also,
n and X each represent the same as in the case of the general formula (V). In the compound represented by the formula (VII), X is an acetoxy group,
A methoxy group or an ethoxy group is preferable,
Particularly, those in which q is 2, 3 or 4 are more preferable.

[0041]

Embedded image

(In the formula (VIII), t and u are each 0 to
5 represents an integer of 5, W is an oxygen atom, a sulfur atom, -SSSS
-, An alkylene group having 1 to 10 carbon atoms, or

[0043]

Embedded image

Is shown. n, X and R ¹⁴ are the same as those in the above formula (V). In addition, R ¹⁵ and R
¹⁶ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a phenyl group. Among the compounds represented by the formula (VIII), those in which X is an acetoxy group, a methoxy group or an ethoxy group are preferable, in particular, m is 2 or 3, and t and u are each 0, 1, 2 or 3 When W represents an alkylene group, those having 2 to 6 carbon atoms are more preferred. Table 2 shows more specific examples of the reactive silane compound used in the present invention, but it is not limited to these.

[0045]

[Table 13]

[0046]

[Table 14]

[0047]

[Table 15]

The organopolysiloxane having at least two Si—H bonds in one molecule (hereinafter abbreviated as “organopolyhydrosiloxane”) used in the present invention reacts with the organopolysiloxane or the reactive silane compound to form a crosslink. It has the function of increasing the film strength and improving the printing ink repellency and image reproducibility of the printing plate under high printing pressure conditions, high temperature printing conditions or multi-sheet printing conditions even in a relatively thin film thickness silicone rubber layer. .

The structure of the organopolysiloxane may be linear, cyclic or branched, but is preferably linear or branched. The Si—H bond may be at the terminal or in the middle of the siloxane skeleton, and the ratio of hydrogen atoms to the total number of the substituents is usually 1% or more and less than 60%. , Preferably 2
It is 0% or more and less than 50%, and more preferably 30% or more and less than 50%. The remaining substituents other than hydrogen atoms are preferably methyl groups in order to obtain good printing ink resilience. Mw of the organopolyhydrosiloxane having at least two Si—H bonds in one molecule is usually 300 to
300,000, preferably 500 to 300,000
It is. Specific examples of preferred organopolyhydrosiloxane include compounds represented by the following general formulas (I) to (III).

[0050]

Embedded image

Of these, the linear organopolyhydrosiloxanes represented by the general formulas (I) and (III) are preferred because of their ease of synthesis, and among them, the linear organopolyhydrosiloxanes represented by the general formula (I) are preferred. Siloxane shows high printing durability,
More preferred.

The silicone rubber layer used in the present invention comprises:
In order to increase the reaction efficiency of the condensation crosslinking reaction between the organopolysiloxane having a hydroxyl group at both ends and the reactive silane compound, the condensation of organic carboxylic acid, titanate ester, stannate ester, aluminum organic ether, platinum-based catalyst, etc. A catalyst is appropriately mixed and a condensation reaction is carried out to cure. The mixing ratio of the organopolysiloxane having a hydroxyl group at each end used in the present invention, the reactive silane compound, and the condensation catalyst in the silicone rubber layer is determined based on the solid content of the entire silicone rubber layer. Polysiloxane is 60 to 98% by weight, preferably 70 to 95% by weight, and the reactive silane compound is usually 1 to 20% by weight, preferably 2 to 20% by weight, more preferably 2 to 15% by weight. 0.1-20% by weight of sun,
It is preferably 0.5 to 15, more preferably 1 to 15% by weight, and the condensation catalyst is 0.05 to 5% by weight, preferably 0.1 to 5% by weight.
It is 1 to 3% by weight, more preferably 0.1 to 1% by weight.

When the ratio of the reactive silane compound or the condensation catalyst is extremely high, the repellency of the printing ink is reduced, and
Removal of the silicone rubber layer during ablation becomes difficult, and 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 resistance is reduced.

When the proportion of the organopolyhydrosiloxane is extremely high, the film strength of the silicone rubber layer decreases,
If the silicone rubber layer peels off from the substrate and is extremely low, on the other hand, the printing ink resilience and image reproducibility under high printing pressure, high temperature or conditions for printing a large number of sheets are reduced. The thickness of the silicone rubber layer used in the present invention is 0.1 to 10 μm.
m, preferably 0.2 to 5 μm, more preferably 0.1 μm.
3 to 2 μm.

The above-described photosensitive layer composition and silicone rubber layer composition 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.

Further, if necessary, the coated sample may be coated with a polypropylene sheet to protect the silicone rubber layer.
Various release plastic sheets such as polyethylene sheet, release treated polyethylene terephthalate, release treated paper,
A metal sheet of aluminum, iron, copper or the like can be laminated on the silicone rubber layer. The photosensitive sample provided with the above-mentioned photosensitive layer and silicone rubber layer on a substrate is subjected to scanning exposure with a beam spot in which a semiconductor laser beam oscillating near-infrared light of 680 to 1100 nm is focused to a diameter of 5 to 30 μm. After the exposed portion is ablated, the exposed portion is used as a printing plate without post-processing.In order to remove fine particles of the photosensitive layer or silicone rubber layer generated by ablation attached to the exposed sample, silicone is used. A post-treatment for applying a physical stimulus such as a brush, a pad, an ultrasonic wave, or a spray may be performed while supplying an aqueous solution or an organic solvent to the surface of the rubber layer as necessary.

As another method for removing the fine particles generated by the ablation, a cover sheet having a surface having a higher adhesiveness to the fine particles than the silicone rubber layer may be used as the silicone rubber of the photosensitive sample used in the present invention. On the layer, before exposure, the silicone rubber surface and the adhesive cover sheet surface are laminated so that they match, and after exposure, the cover sheet is peeled off, a method of removing fine particles on the silicone rubber layer, or the exposed sample silicone. A method of laminating a cover sheet on a rubber layer in the same manner as described above and then peeling off the cover sheet may be used. 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.

[0058]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. Example 1 A substrate obtained by coating a photosensitive layer composition having the following composition on a substrate was a foamed polypropylene film (GWG manufactured by Oji Yuka Co., Ltd.).
Was used. (Photosensitive layer composition) Near-infrared absorbing agent: NK3027 (manufactured by Nippon Kogaku Co., Ltd.) 50 parts by weight Organic polymer substance: nitrocellulose (RSI / 16 manufactured by Daicel) 50 parts by weight Coating solvent: N-methyl-2 -Pyrrolidone 1175 parts by weight Cyclohexanone 390 parts by weight Surfactant: L7002 (manufactured by Nippon Unicar) 0.8 part by weight After application, the coating was dried at 100 ° C for 2 minutes to provide a photosensitive layer having a dry film thickness of 1 µm. Subsequently, a silicone rubber layer composition having the following composition was applied onto the photosensitive layer.

(Silicone Rubber Layer Composition) Linear Organopolysiloxane Having Hydroxyl Groups at Both Terminals: Compounds in Table 3, Compounding Amounts in Table 3 Reactive Silane Compounds: Compounds in Table 3 Additives listed in Table 3 Additives (substituted polysiloxanes other than those listed above): Compounds listed in Table 3, Compounded amounts listed in Table 3 Condensation catalyst: 0.8 parts by weight of dibutyltin dilaurate Coating solvent: Isopar E (manufactured by Exxon Chemical) 1700 parts by weight

After the coating, the coating was dried at 100 ° C. for 4 minutes, and a silicone rubber layer having a dry film thickness shown in Table 3 was provided to prepare a photosensitive sample. The photosensitive lithographic printing plate is fixed on a rotating drum having a circumference of 21 cm so that the silicone rubber layer is on the outside,
The drum was rotated. Next, on the rotating printing plate,
A 30 nm, 30 mW semiconductor laser (HL8325G, manufactured by Hitachi, Ltd.) was condensed to a beam diameter of 22 μm, and scanning exposure was performed. Subsequently, the following items were evaluated. Table 3 shows the results.

(Sensitivity) Printing was performed using the exposed photosensitive lithographic printing plate under the following conditions. [Printing conditions]-Printing machine: DAIYA IF-2-Printing speed: 6000 sheets / H-Ink: New ALPO-G indigo L (manufactured by T & K Toka)-Printing paper: OK special art (manufactured by Oji Paper)-Seal Pressure: High printing pressure condition 60 μm higher than standard Nip width at standard printing pressure 7.8 to 8.8 mm between plate and blanket 4.6 to 5.5 mm between plate and inking roller ・ Number of prints: 20000 sheets obtained The ink image of the printed matter was observed with a microscope of 100 times, and the sensitivity was evaluated based on the maximum scanning speed (cm / s) of the laser when an ink image corresponding to the laser-exposed portion was obtained. The higher the scanning speed, the higher the sensitivity. The abbreviation F in the column of sensitivity in Table 3 indicates that a printed image was not formed.

(Background Smear) The amount of ink adhering to the non-image area of the printed matter (background smear) was measured using a Macbeth densitometer (TR927, SPI
The measurement and evaluation were performed using a filter (for cyan). A: The optical density of the non-image area was less than 0.01. B: The optical density of the non-image area was 0.01 or more and less than 0.02. C: The optical density of the non-image area was 0.02 or more and less than 0.04. D: The optical density of the non-image area was 0.04 or more and less than 0.10. E: The optical density of the non-image area was 0.10 or more and less than 0.30. F: The optical density of the non-image area was 0.30 or more.

[0063]

[Table 16]

[0064]

[Table 17]

In Table 3, the abbreviations in the column of the linear organopolysiloxane having hydroxyl groups at both terminals represent the following polysiloxanes. Trade name Y1: YF3897 (Mw = 800000, manufactured by Toshiba Silicone Co., Ltd.) Y2: YF3802 (Mw = 80000, manufactured by Toshiba Silicone Co., Ltd.) Y3: YF3807 (Mw = 20000, manufactured by Toshiba Silicone Co., Ltd.) Abbreviations (Si1, S
i2, Si3, Si4, Si19, Si21, Si2
3, Si25, Si26, Si31, and Si32) represent the compounds described in Table 2, respectively. In Table 3, abbreviations of additives represent the following polysiloxanes, respectively.

[0066]

Embedded image

[0067]

According to the present invention, a laser direct dampening solution-free photosensitive lithographic plate excellent in printing suitability such as ink repulsion and image reproducibility of a printing plate under high printing pressure, high-temperature printing conditions or multi-sheet printing conditions. Printing plate can be provided.

Claims (5)

[Claims] 1. A laser-direct fountain-free photosensitive lithographic printing plate having, on a substrate, a photosensitive layer containing at least a near-infrared absorber from the substrate, and a silicone rubber layer in this order. (A) a linear organopolysiloxane having hydroxyl groups at both ends of 60% by weight or more and less than 98% by weight based on the total solid content of the silicone rubber layer, and (b) 1% based on the total solid content of the silicone rubber layer.
(C) at least 0.1% by weight and less than 20% by weight based on the total solid content of the silicone rubber layer, and at least two Si-H bonds in one molecule. A photosensitive lithographic printing plate which does not require a laser direct dampening solution, comprising an organopolysiloxane having the same. 2. The photosensitive lithographic printing plate according to claim 1, wherein the reactive silane compound has six or more alkoxy groups. 3. The photosensitive lithographic printing method according to claim 1, wherein the weight average molecular weight of the organopolysiloxane having at least two Si—H bonds in one molecule is 300 to 300,000. Edition. 4. The method according to claim 1, wherein the proportion of hydrogen atoms in the substituents on the silicon atoms of the organopolysiloxane having at least two Si—H bonds in one molecule is from 20% to 50%.
The photosensitive lithographic printing plate according to claim 1, wherein the lithographic printing plate does not require a laser direct dampening solution. 5. The laser according to claim 1, wherein the organopolysiloxane having at least two Si—H bonds in one molecule is a linear organopolysiloxane represented by the following general formula (I). A photosensitive lithographic printing plate that does not require direct dampening water. Embedded image (In the general formula (I), x ¹ represents an integer of 2 or more.)