JPH04107557A - Erasing liquid for dampening waterless photosensitive planographic printing plate and erasing method formed by using this erasing liquid - Google Patents

Abstract

PURPOSE:To improve workability and printability by consisting a solvent of a specific paraffinic hydrocarbon, isoparaffinic hydrocarbon, cycloparaffinic hydrocarbon, etc. CONSTITUTION:This erasing liquid contains at least silicone rubber, a silane coupling agent and the solvent. This solvent is the paraffinic hydrocarbon, isoparaffinic hydrocarbon, cycloparaffinic hydrocarbon, arom. hydrocarbon having 30 to 85 deg.C b. p. and the mixture composed thereof. The amt. of the silane coupling agent to be added in this case is preferably 1 to 9wt.% with the weight of the silicone rubber in this case. The workability and printability are improved in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an erasing liquid for photosensitive lithographic printing plates that does not require dampening water and an erasing method using the erasing liquid. The present invention relates to an erasing liquid for photosensitive planographic printing plates that does not require dampening water. The present invention also relates to an erasing method using this erasing liquid.

[Conventional technology] Conventional printing methods that require dampening water have difficulty controlling the delicate balance between dampening water and ink, causing emulsification of the ink, or causing ink to mix with the dampening water, resulting in poor ink density. However, the photosensitive lithographic printing plate, which does not require dampening water, has a primer layer, a photosensitive layer, and a silicone layer formed on a support in this order. , has numerous advantages as it does not require dampening water.

[Problems to be solved by the invention] However, the silicone layer is relatively prone to scratches when handled, and the resulting scratches and
Pinhole-like defects, defects based on film edges, etc.
- It was inconvenient to use because there was no appropriate means to correct the defects that occurred.

On the other hand, there are cases in which it is desired to erase not only an unexpected defect but also an erroneously drawn drawing part, or to intentionally erase the drawing part to make it a non-drawing part.

Various studies have been conducted on erasing liquids for this purpose. However, conventional erasing liquids have drawbacks such as background smearing, slow curing speed, and workability problems, and the current situation is that a satisfactory erasing liquid has not yet been obtained.

Therefore, an object of the present invention is to provide a novel erasing liquid for photosensitive lithographic printing plates that does not require dampening water and eliminates all of the above-mentioned disadvantages.

Another object of the present invention is to provide an erasing method that can effectively use a new erasing liquid.

"Means for Solving the Problems" As a result of intensive research in view of the above problems, the present inventors have found that
The above object of the present invention is to provide an erasing solution for a photosensitive lithographic printing plate that does not require dampening water and contains at least a silicone rubber, a silane coupling agent, and a solvent, wherein the solvent has a boiling point of 30°C to 85°C.
paraffinic hydrocarbons, isoparaffinic hydrocarbons,
This is achieved by an erasing liquid for photosensitive lithographic printing plates that does not require dampening water and is characterized by being a cycloparaffinic hydrocarbon, an aromatic hydrocarbon, or a mixture thereof. In this case, the amount of the silane coupling agent added is preferably 1 to 9% by weight based on the weight of the silicone rubber.

Further, the above object of the present invention is to have at least a primer layer, a photosensitive layer, and a silicone rubber layer on a support in this order from the support side, and the primer layer contains at least a hydroxyl group-containing polymer, a polymerizable monomer, and a photopolymerization initiator. Contains
A dampening water-less photosensitive lithographic printing plate, characterized in that the dampening water-less light-sensitive lithographic printing plate, the photosensitive layer of which contains at least a hydroxyl group-containing polymer and a diazo resin, is treated with the erasing liquid according to claim 2. This is accomplished by the erasing method.

The present invention will be explained in more detail below.

The erasing solution for photosensitive lithographic printing plates that does not require dampening water of the present invention contains at least a silicone rubber, a silane coupling agent, and a solvent.

The silicone rubber is preferably a linear or somewhat crosslinked organopolysiloxane. The organopolysiloxane usually has a molecular weight of 1 to 10 yen, and is not liquid at room temperature (it is moderately crosslinked in the form of wax or rice cake). However, in the present invention, it is preferable to carry out condensation type crosslinking.

In the condensed type, crosslinking is performed by a condensation reaction, and water, alcohol, organic acid, etc. are released by the reaction. Particularly preferred are a mixture of a linear organopolysiloxane having hydroxyl groups at both ends or a part of the main chain and a silicone crosslinking agent, or a mixture of a silicone crosslinking agent reacted with the hydroxyl group, both of which contain a condensation catalyst. is advantageous in terms of crosslinking speed.

The organopolysiloxane has the following repeating units in its main chain.

In the formula, R and R2 are alkyl, aryl, alkenyl, or a combination thereof, each of which may have a substituent such as a cyano group, a halogen atom, a hydroxyl group, and a methyl group, a phenyl group, a vinyl group, or a trifluoropropyl group. is preferred, and methyl group is particularly preferred.

Furthermore, the main chain in one organopolysiloxane may contain different repeating units.

Among the commercial products available as the silicone rubber according to the present invention, preferred examples include KS-705F manufactured by Shin-Etsu,
KE-41, 42, 44, Toshiba Silicone (manufactured) Y
F5505. YF3057. YF3802, Toshi Silicone (manufactured) 5H-781, PRX-305, 5H
Condensation type silicone rubber such as No. 237 can be mentioned.

A silane coupling agent is used as a crosslinking agent in the erasing liquid of the present invention. Examples of the silane coupling agent include tetraacetoxysilane, methyltriacetoxysilane, ethyltriacetoxysilane, phenyltriacetoxysilane, and vinyltriacetoxysilane.

In the present invention, the silane coupling agent is preferably used in an amount of 1 to 9 parts, more preferably 3 to 8 parts, based on 100 parts of silicone rubber.

The erasing solution of the present invention contains organic carboxylates of metals such as tin, zinc, lead, calcium, and manganese, chloroplatinic acid, and the like as catalysts. Specific examples of catalysts preferably used in the present invention include dibutyltin laurate, tin octylate, and lead naphthenate. In the present invention, the catalyst is preferably used in an amount of 03 to 6 parts, more preferably 05 to 5 parts, based on 100 parts of silicone rubber.

The solvent used in the erasing liquid of the present invention has a boiling point of 30
Examples include paraffinic hydrocarbons, isoparaffinic hydrocarbons, cycloparaffinic hydrocarbons, aromatic hydrocarbons, and mixtures thereof in the range of .degree. C. to 85.degree. In the present invention, it is preferable to use a solvent with a boiling point of 60°C to 80°C. Specifically, for example, n-pentane, n-hexane, 2-methylpentane, 2,2-dimethylbutane,
2.3-dimethylbutane, benzene, cyclopentane,
Examples include methylcyclopentane, cyclohexane, cyclohexene, petroleum ether, petroleum benzine, etc., but n-hexane or cyclohexane is preferred.

In the present invention, the above-mentioned solvent varies depending on the molecular weight of the silicone rubber used, but for example, the molecular weight Mw = 70.0
100 to 100 parts per 100 parts of silicone rubber
It is preferably used in the range of 0 parts, more preferably 200 parts.
~800 copies.

In the present invention, in addition to the above-mentioned components, the erasing liquid contains silicone rubber, coloring agents such as dyes and pigments, fillers for the purpose of improving the strength of silicone rubber, and other various additives. It can be added in an amount not exceeding 20 parts.

Colorants preferably used in the present invention include, for example, Victoria Pure Blue BOH, Crystal Violet, etc., and fillers include, for example, silica, zinc oxide,
Examples include inorganic fillers such as titanium oxide and aluminum oxide. From the viewpoint of dispersibility or dispersion stability, such fillers preferably have an average particle diameter of 500 nm or less.

The concentration of the coating liquid depends on the molecular weight of the organopolysiloxane used and the coating method, but is 2 to 100% by weight, preferably 5 to 30% by weight, and more preferably 10 to 20% by weight.
It is. If it is too thin or too thick, it will not be possible to obtain a thin silicone rubber film with an appropriate thickness.

Such erasing fluid can be applied to the repaired area using conventional tools such as brushes, sponges, pipettes, and syringes. When printing tens of thousands of sheets or more using such corrected printing plates, the adhesion of the corrected parts may be weak and they may fall off due to fatigue, or they may fall off due to rubbing when cleaning the prints during printing. There may be a problem that it is easy to get stuck. As a means to solve these practical printing problems, for example, a large amount of erasing liquid is applied to the corrected area,
By increasing the thickness of the silicone rubber layer in the repaired area, resistance to rubbing etc. can be improved to some extent, but such measures are not recommended if there are restrictions on the inside of the image or the area to be erased. Very difficult. In particular, strong adhesive strength is required when forming an independent silicone rubber layer within a pattern or in a drawing area, or when creating minute halftone dots of several tens of microns.

In such a case, in a waterless lithographic printing plate having a photopolymerizable adhesive layer and a silicone rubber layer on a support, after applying an erasing liquid, the coated area is irradiated with actinic rays, or
Alternatively, heating by appropriate means is extremely effective.

Furthermore, it is particularly effective to add a thermal polymerization or photopolymerization initiator as necessary. As these initiators, azobisisobutyronitrile and benzoin isobutyl ether are preferably used. In addition, we can laminate a substantially transparent protective film or irradiate it after forming a protective film.
Or it is even more effective when heated. Also effective are methods of irradiating in water, in an inert gas such as nitrogen gas, or in a vacuum. As the above-mentioned protective film,
Various commonly used films such as polyester, polyethylene, polypropylene, cellophane, etc. can be used.

The protective coating may be formed by applying various liquids or solutions, especially viscous liquids or polymer solutions with low oxygen permeability, followed by irradiation or heating, either while wet or after drying. be. In particular, it is preferable to use an aqueous solution of polyvinyl alcohol, methylcellulose acetate, or the like. Furthermore, when correcting only a minute defect within a pattern, it is also possible to protect only the corrected area with a transparent adhesive tape or the like and then irradiate or heat the area.

The erasing liquid of the present invention has on a support at least a primer layer, a photosensitive layer, and a silicone rubber layer in this order from the support side, and the primer layer contains at least a hydroxyl group-containing polymer, a polymerizable monomer, and a photopolymerization initiator. However, it is preferably used for a dampening water-free photosensitive lithographic printing plate in which the photosensitive layer contains at least a hydroxyl group-containing polymer and a diazo resin.

In the present invention, the primer layer is a hydroxyl group-containing polymer,
Contains an ethylenically unsaturated monomer or oligomer and a photopolymerization initiator.

As the hydroxyl group-containing polymer, esters or amides of alcoholic hydroxyl group-containing poly(meth)acrylic acid are preferably used.

In addition, in the present invention, when an acrylic compound and a methacrylic compound are jointly referred to below, [(meth)acrylic compound 1]
Write it like this.

Examples of polymers having alcoholic hydroxyl groups include 2-hydroxyethyl (meth)acrylate, N-(4
-Hydroxyethylphenyl)methacrylamide, hydroxymethyldiacetone(meth)acrylamide, and the like having structural units derived from monomers such as (meth)acrylamide and the like. In particular, polymers having structural units derived from 2-hydroxyethyl (meth)acrylate are preferred.

The above-mentioned alcoholic hydroxyl group-containing polymer may be a copolymer, and the copolymer component includes (1) a heptadmer having an aromatic hydroxyl group, such as N-(4
-Hydroxyphenyl)(meth)acrylamide, 0-
α, β of 1m-1p-hydroxystyrene, 0-1m-1p-hydroxyphenyl (meth)acrylate, (2) (meth)acrylic acid, maleic anhydride, etc.
-Unsaturated carboxylic acids, (3) methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (
meth)acrylate, amyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate, 2-chloroethyl acrylate, 2-hydroxyethyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, glycidyl(meth)acrylate acrylate, optionally substituted alkyl (meth)acrylate such as N-dimethylaminoethyl (meth)acrylate, (4) (meth)acrylamide, N-methylol (meth)acrylamide, N-ethylacrylamide, N-hexyl Optionally substituted (meth)acrylamides such as methacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl-N-phenylacrylamide, (5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ethyl, octyl vinyl ether, phenyl vinyl ether, etc. (6) Vinyl such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate, etc. Esters, (7) Styrenes such as styrene, α-methylstyrene, chloromethylstyrene, (8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, phenyl vinyl ketone, (9) Ethylene, propylene (10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, and the like. Particularly preferred are (1) to (3).

The amount of hydroxyl group-containing monomer in the hydroxyl group-containing polymer is not particularly limited, but is preferably 5 to 100% by weight.
, particularly preferably 20 to 100% by weight.

The weight average molecular weight of the hydroxyl group-containing polymer of the present invention measured by gel permeation chromatography (GPC) is preferably 5,000 to 1,000,000 (in terms of styrene). If the value is lower than 5,000, it may be damaged by the coating solvent or developer for the photosensitive layer even after photocuring, and if the value is greater than 1,000,000, it is difficult to select a coating solvent.

The proportion of the hydroxyl group-containing polymer in the brimer layer is usually 10 to 99% by weight, preferably 40 to 97% by weight.

In addition, the ethylenically unsaturated monomer or oligomer used in the present invention is a compound containing two or more terminal ethylene groups that can be polymerized at the boiling point under normal pressure or 100°C or higher, and various known ones can be used. can. For example, unsaturated carboxylic acids, esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds, esters of unsaturated carboxylic acids and aromatic polyhydroxy compounds, unsaturated carboxylic acids and polyhydric carboxylic acids, and the aforementioned aliphatic polyhydroxy compounds. hydroxy compound,
Examples include esters obtained by esterification reactions with polyhydric hydroxy compounds such as aromatic polyhydroxy compounds, and are specifically described in JP-A-59-71048, such as diethylene glycol di(meth) Acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol triacrylate, hydroquinone di(meth)acrylate, pyrogallol triacrylate, 2,2'-bis(4-acryloxy-jethoxyphenyl) ) Propane, etc.

Other examples include (meth)acrylamide, hexamethylenebis(meth)acrylamide, etc.
Examples include acrylamides, vinyl urethane compounds, and epoxy (meth)acrylates.

In the present invention, the amount of the ethylenically unsaturated monomer or oligomer in the brimer layer is 10 to 90% by weight.
and preferably 20 to 80% by weight.

Further, as the photopolymerization initiator, conventionally known ones can be used, and for example, benzoin, benzoin alkyl ether, benzophenone, anthraquinone, benzyl, Michler's ketone, a complex system of biimidazole and Michler's ketone, etc. can all be suitably used.

The amount of the photopolymerization initiator in the brimer layer is from 01 to 20% by weight, preferably from 02 to 10% by weight.

In the present invention, in addition to the above components, the primer layer may contain other fillers or antihalation agents, colorants such as dyes and pigments, coating improvers, plasticizers, stabilizers,
It may also contain an oil sensitizing agent or the like in an amount not exceeding 10% by weight. It is also possible to use in combination various conventionally known polymers, such as polyamide and polyurethane, which are usually used in the brimer layer.

Examples of dyes that can be included in the primer layer include Victoria Pure Blue BOH.

Oil Blue #603, Oil Pink #312, Patent Pure Blue, Crystal Violet, Leuco Crystal Violet, Brilliant Green, Ethyl Violet, Methyl Green, Erythrosin B1 Basic Tsushin, Malachite Green, Leucomalachite Green, m-Cresol Purple, Cresol Red , xylenol blue, rhodamine B1 auramine, 4
Examples include triphenylmethane-based, diphenylmethane-based, oxazine-based, xanthine-based, iminonaphthoquinone-based, azomethine-based, and anthraquinone-based dyes represented by -p-diethylaminophenylimino naphthoquinone, cyano-p-diethylaminophenyl acetanilide, and the like.

Examples of coating properties improvers include alkyl ethers (e.g., ethyl cellulose, methyl cellulose), fluorine-based surfactants, nonionic surfactants (e.g., Pluronic L-64 (manufactured by Asahi Denka)), FC-430 (Sumitomo 3M), etc. ), etc.

Examples of plasticizers for imparting flexibility and abrasion resistance to coating films include butylphthalyl, polyethylene glycol,
Examples include tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrafurfuryl oleate, oligomers of acrylic acid or methacrylic acid, etc. .

In addition, in order to improve the printing ink adhesion of images, various additives having hydrophobic groups, such as p-octylphenol/formalin novolac resin, pt-butylphenol/formalin novolak resin, pt-butylphenol/benzaldehyde resin, are also used. , a modified novolac resin such as a rosin-modified novolak resin, or an 0-naphthoquinonediazide sulfonic acid ester (esterification rate of OH group: 20 to 70 mol %) of these modified novolak resins can be used.

If the primer composition contains a pigment, the primer composition may be prepared using a known dispersion method (
After dispersing with SGI, homogenizer, etc.), it is filtered. The primer layer of the present invention is formed by applying the dispersion onto a support, drying it, and then photocuring it.

For photocuring, a known light source such as a mercury lamp, xenon lamp, or natural light is used, and the amount of exposure (
Usually, for example, 50mJ/cm to 5J/cry? range)
This can be done by exposing to light.

Further, the above-mentioned curing is desirably carried out at least before the coating of the photosensitive layer is completed, and more preferably immediately after coating.

In the present invention, the thickness of the primer layer is 1 mg/drr.
? It is preferably ~500mg/drrr, more preferably 3mg/drd~300mg/d
It is rrr.

In the present invention, a photosensitive layer is provided on the primer layer, but any photosensitive layer that can be used in the present invention can be used as long as its solubility in a developer changes before and after exposure. be.

Specifically, for example, 0-quinonediazide compound, 0-
Examples include a commercially solubilized photosensitive layer containing a nitrobenzyl carbinol ester compound and the like, a photoinsolubilizable photosensitive layer containing a diazo compound, a compound having an addition polymerizable vinyl group, and the like.

The above-mentioned 0-quinonediazide compounds are compounds having at least one 0-quinonediazide group, preferably a 0:benzoquinonediazide group or an 0-naphthoquinonediazide group, and include known compounds of various structures, such as those described in J. Kosar's book Light Sensitive Systems” (published by John Wiley & Sams, 1965)
Compounds described in detail on pages 339 to 353 are included.

For example, various hydroxyl compounds and benzoquinone-1
, 2-diazide sulfonic acid, naphthoquinone-1,2-diazide sulfonic acid, and the like. Examples of the hydroxyl compound used include resins obtained by condensation of phenols such as phenol, cresol, and pyrogallol with carbonyl group-containing compounds such as formaldehyde, benzaldehyde, and acetone, particularly resins obtained by condensation in the presence of an acidic catalyst. .

As a photosensitive layer containing a diazo compound, JP-A-1-104
A photosensitive layer disclosed in Japanese Patent No. 286, which contains a diazo resin and a (meth)acrylic acid ester or amide-containing polymer having a hydroxyl group as essential components, is preferred.

In the case of such a photosensitive layer, the proportion of the diazo resin in the photosensitive layer is preferably 1 to 90% by weight, more preferably 3% by weight.
~60% by weight.

Examples of compounds having an addition polymerizable vinyl group include compounds having a boiling point of 100° C. or higher under normal pressure and having two or more polymerizable terminal ethylene groups, such as unsaturated carboxylic acids,
Esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds, esters of unsaturated carboxylic acids and aromatic polyhydroxy compounds, unsaturated carboxylic acids and polycarboxylic acids, and the aforementioned aliphatic polyhydroxy compounds, aromatic polyhydroxy Examples include esters obtained by an esterification reaction with a polyhydric hydroxy compound, and are specifically described in JP-A-59-71048 and the like.

In the present invention, all of the above-mentioned photosensitive layers can be used, but a photosensitive layer containing a diazo resin is preferred from the viewpoint of adhesion to the primer layer.

Further, in the present invention, in addition to the above-mentioned materials, dyes, pigments, known exposure visible image agents, coating property improvers, etc. may be added to the photosensitive layer to improve the developable visible image property.
Exposure visibility and coating properties can be improved.

Further, in the present invention, it is preferable that the photosensitive layer contains a hydroxyl group-containing polymer. As such a hydroxyl group-containing polymer, the same polymers as those used in the primer layer described above can be used.

Is the thickness of the photosensitive layer 0.1mg/drr? ~30mg/dr
r? is preferable, and 0.5 mg/d resistance to 10 mg/d resistance is more preferable.

In the present invention, a silicone rubber layer is further provided on the photosensitive layer, and the silicone rubber used in the silicone rubber layer is preferably linear or crosslinked organopolysiloxane. The organopolysiloxane usually has a molecular weight of 10 to 100 yen, and is suitably crosslinked in the form of a liquid, wax, or cake at room temperature. The organopolysiloxane is classified into condensed type and addition type depending on the method of crosslinking, and in the present invention, condensed type is used.

In the condensed type, crosslinking is performed by a condensation reaction, and water, alcohol, organic acid, etc. are released by the reaction. Particularly useful condensation type silicone rubbers include a mixture of a linear organopolysiloxane having hydroxyl groups at both ends or a part of the main chain and a silicone crosslinking agent, or one in which the hydroxyl groups are reacted with a silicone crosslinking agent. In either case, adding a condensation catalyst is advantageous in terms of crosslinking speed.

The organopolysiloxane has the following repeating units in its main chain.

R engineering→5t-0← In the formula, RL and R2 are alkyl, aryl, alkenyl, or a combination thereof, each of which may have a substituent such as a cyano group, a halogen atom, or a hydroxyl group, and a methyl group, a phenyl group, or a vinyl group. A trifluoropropyl group is preferred, and a methyl group is particularly preferred.

The silicone crosslinking agents mentioned above include the so-called acetic acid-removal type, oxime-elimination type, alcohol-elimination type, deamination type, dehydration type, and those having a functional group represented by -0H (in the formula, R and R' are alkyl groups). Examples include condensed silicone crosslinking agents such as molds. Examples of such crosslinking agents include tetraacetoxysilane, methyltriacetoxysilane, ethyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane,
Diethyldiacetoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltris(acetoneoxime)silane, methyltri(N-methyl,
Examples include N-acetylamino)silane, vinyltri(methylethylketoxime)silane, methyltri(methylethylketoxime)silane or oligomers thereof, and reactive silane compounds having an isocyanurate group.

All of these crosslinking agents are organopolysiloxane 10
It is preferable that the amount is in the range of 05 to 30 parts by weight relative to 0 parts by weight.

Examples of the condensation catalyst include dibutyltin dilaurate, dibutyltin acetate, dibutyltin maleate, and the like.

Among the commercially available silicone rubbers according to the present invention, preferred examples include KS-705F manufactured by Shin-Etsu,
KE-41, 42, 44, Toshiba Silicone (manufactured) Y
E 5505. Y F 3057, Toshi Silicone (manufactured by) SH-781, PRX-305, 5H-237
Condensation type silicone rubbers such as

Furthermore, for the purpose of improving the strength of silicone rubber, inorganic fillers such as silica, titanium oxide, and aluminum oxide may be added, and silica is particularly preferably used.

From the viewpoint of dispersibility or dispersion stability, such fillers preferably have an average particle diameter of 500 nm or less.

In the present invention, the thickness of the silicone rubber layer is preferably as thin as possible from the point of view of image quality and developability, but on the other hand, a certain degree of thickness is required from the point of view of stiffness resistance, printing stains, etc., so generally 3 mg/ drrr? -50mg/drr? is preferable, and 5 mg/d to 30 mg/d is more preferable.

Furthermore, the photosensitive lithographic printing plate that does not require dampening water of the present invention may have a protective layer on top of the silicone rubber layer, and a method for providing the protective layer is to laminate a polypropylene film or the like as described in Japanese Patent Publication No. 61-614. How to do it and JP-A-61-2
A method of applying a high molecular weight polymer described in No. 7545 is known.

As the support used in the present invention, any support can be used as long as it has the flexibility to be set in a normal lithographic printing machine and can withstand the load applied during printing, and there are no particular restrictions on the layer structure. Not done. Examples include papers such as coated paper, metal plates such as aluminum plates, and plastic films such as polyethylene terephthalate, but aluminum plates or composite materials of aluminum foil and other materials are preferred.
In terms of printing durability, aluminum plates are particularly preferred.

In the present invention, the photosensitive lithographic printing plate prepared as described above is imagewise exposed, developed with a developer to dissolve the photosensitive layer, and removed together with the silicone rubber layer thereon, resulting in the primer layer forming an image area. Upon exposure, a dampening water-less lithographic printing plate is formed.

In this case, it is preferable to dye the image area with a dye during or after development.

For such dyeing, a dyeing solution containing water as a main component and a dye as an essential component is used.

Preferred dyes include specifically the following acidic dyes and basic dyes.

Acidic dyes include nitro dyes, such as Naphthol Yellow (C,1, Acid Yellow 1), monoazo dyes, such as Fast Red A (C.

■, Acid Red 88), disazo dyes such as Naphthol Blue Black (C, I Acid Black 1), nitroso dyes such as Naphthol Green B
(C,I Acid Green 1), triphenylmethane dyes such as Patent Blue (C,I Acid Blue 3), Brilliant Milling Green B (C,
I acid green 9), xanthine dyes such as sulforhodamina B (C,1, acid red 52)
), anthraquinone dyes, such as Alizarin Direct Blue A2G (C, I Acid Blue 40), azine dyes, such as Wool Fast Blue L (C
, 1, Acid Blue 102), quinoline dyes, such as Quinoline Yellow (C, 1, Acid Yellow 3), etc., and specific examples of preferable basic dyes include the following.

Diphenylmethane dyes, such as auramine O (C, I Basic Yellow 2), triphenylmethane dyes, such as magenta (C, ■, Basic Violet 14)
), methyl violet (C,I Basic Violet 1), malachite green (C,I, Basic Green 4), thiazole dyes such as Thioflavin T (C,I Basic Yellow 1), xanthine dyes such as Rhodamine B (C,I Basic Violet 10), oxazine dyes such as Neil Blue BX (CI Basic Blue 12), thiazine dyes such as Methylene Blue B (C,I Basic Blue 9), azine dyes such as Safranin T (C, I
Basic Red 2), azo dyes such as Bismarck Brown G (C,I Basic Brown 1), indocyanine dyes such as Astrafracin FF (C
, I Basic Red 12) etc. In the present invention,
In particular, triphenylmethane dyes are preferably used.

These dyes are used in aqueous solutions, the concentration of which is 0.1
g/f to 10 g/l is preferred.

In the present invention, when dyeing is performed using these dye aqueous solutions, the concentration thereof is 10°C to 50°C. In addition, the dyeing method is
This is carried out by immersing the developed printing plate in a dye solution, or by coating or shower-spraying an aqueous dye solution onto the printing plate. A dyeing aid may be added to this dye aqueous solution as required.

As dyeing aids, water-soluble organic solvents, surfactants, etc. are used to facilitate dyeing of the brimer layer.

As the organic solvent, ethanol, tulfite, benzyl alcohol, etc. are preferably used, and as the surfactant, nonionic surfactants are preferred from the viewpoint of foaming properties.

As the light source used for exposure, any general-purpose light source including ultraviolet rays of 180 nm or more and visible light may be used, but carbon arc lamps, mercury lamps, xenon lamps, metal halide lamps, strobes, etc. are particularly preferred.

The developer used in the development process includes water, the following polar solvents, alkaline compounds such as amines, surfactants, aliphatic hydrocarbons (hexane, heptane, "Isopar E,"
H,G” (trade name of aliphatic hydrocarbons manufactured by Esso Chemical)
Or gasoline, kerosene, etc.), aromatic hydrocarbons (toluene, xylene, etc.), or halogenated hydrocarbons (triclene, etc.) are added as necessary.

Shinsho Silkworm 1 Alcohols (methanol, ethanol, β-anilinoethanol, propylene glycol, etc.) Ethers (
Methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carpitol, ethyl carpitol, butyl carpitol, dioxane, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (ethyl acetate, methyl cellosolve acetate, cellosolve acetate, carpitol acetate, etc.) Development This can be carried out by various known methods, such as rubbing with a developing pad containing the developer as described above, or pouring the developer onto the printing plate and then rubbing with a developing brush.

[Examples] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

(Synthesis of Diazo Resin-1) 145 g of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under water cooling. IOg of paraformaldehyde was slowly added dropwise to this reaction solution so that the reaction temperature did not exceed 10°C. Thereafter, stirring was continued for 2 hours under water cooling. This reaction mixture was added dropwise to 5001Q ethanol under water cooling, and the resulting precipitate was filtered. After washing with ethanol, this precipitate was dissolved in 100 d of pure water, and to this solution was added a cold concentrated aqueous solution in which 6.8 g of zinc chloride was dissolved. The resulting precipitate was filtered, washed with ethanol, and dissolved in 1501 g of pure water. To this liquid was added a cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved. The resulting precipitate was collected by filtration, washed with water, and then dried at 30°C all day and night to obtain diazo resin-1.

The styrene-equivalent weight average molecular weight (MW
) was 1500, and the number average molecular weight was 500.

1-4 1-2 On a degreased aluminum plate (manufactured by Mitsubishi Aluminum) with a thickness of 0.24 mm, the following primer layer composition was applied at 60°C with a whirler, and dried and exposed to provide a primer layer. . However, after coating and drying (100° C. for 2 minutes), exposure was carried out at Unicure (manufactured by Ushio Inc.) -160W and 4 m/min.

(Primer layer composition) (1) Copolymer resin (Mw
= 4. OX 10') 100 parts (2) 80 parts of pentaerythritol triacrylate (3) DETX 3 parts (4) EPA 3 parts (5) KET-YELLOW402 (yellow pigment manufactured by Dainippon Ink ■) 8 parts (6) Zinc oxide (Average particle size: 0.12μ) 20 parts (
7) 10 parts of T S L-8331 (HJ(CH2)sSi(OCJa)a) (Toshiba Silicone) A photosensitive composition having the composition shown below was coated on the above primer layer and dried at 80°C for 2 minutes to give a thick layer. A photosensitive layer with a thickness of 0.3 μm was formed.

(Photosensitive composition) (1) Diazo resin - 1100 parts (2) 2-hydroxyethyl methacrylate, N-(4
-hydroxyphenyl) methacrylamide and methacrylic acid in a molar ratio of 40/5515 (Mw = 4
．． 2x 10') 100 parts (3) Orange ■ 8 parts (4)
Methyl lactate 900 parts Next, the following silicone rubber composition was applied to the photosensitive layer to a thickness of 2.0 g/
rn'' and dried at 90°C for 10 minutes.

(Silicone rubber layer composition) (1) 100 parts of dimethylpolysiloxane (molecular weight 52,000) having hydroxyl groups at both ends (2) The following reactive silane compound (3) Dibutyltin dilaurate 0.8 parts (4
) Isopar E (manufactured by Esso Chemical) 900 parts Next, a single-sided matted polypropylene film having a thickness of 6 μm was laminated on the silicone rubber layer to obtain a photosensitive lithographic printing plate that did not require dampening water.

A positive film was vacuum-adhered to the top surface of the obtained photosensitive lithographic printing plate that did not require dampening water, exposed using a metal halide lamp, and immersed in the following developer for 1 minute, and then the surface of the plate material was impregnated with the following developer. The unexposed portions of the silicone rubber layer and photosensitive layer were removed by rubbing with a damp pad. Next, the image area was dyed with the following staining solution to obtain a printing plate.

However, at this time, PET films (2 cm x 2 cm) of different thicknesses were attached to the positive film to create unnecessary lines (sticking marks), and these unnecessary lines were erased with an erasing liquid having the composition shown below. The curing time and print stain for each erasing liquid were measured.

Printing was performed using Toyo Ink's Aquares-Five TMP ink using a Heidel GTO printing machine with the ink dampening water supply device removed, and the resulting printed matter was visually evaluated. The results are shown in Table-1.

(Developer composition) Potassium silicate 9 parts Potassium hydroxide 4 parts Propylene glycol 5 parts Water
82 parts (staining liquid composition) Tulfit (manufactured by Clarei Soprene Chemical ■) 20 parts Reshidol TWO-120 (surfactant manufactured by Kao ■) 05 parts benzyl alcohol 5 parts Victoria Pure Blue BOH 1 part water
100 parts (erasing liquid composition) Silicone rubber YF-3802 (Toshiba Silicone ■) 100 parts Silane coupling agent T S L -8180 (Toshiba Silicone ■) (Listed in Table 1) Catalyst Dibutyltin dilaurate 1 part Solvent (Table 1 )
500 copies or less Margin, -1, A As is clear from Table 1, when the erasing liquid of the present invention is used, the curing time is short, that is, the erasing operation time can be shortened, and printing stains do not occur.

[Effects of the Invention] As explained in detail above, the present invention has been able to provide an erasing liquid for photosensitive planographic printing plates that does not require dampening water and has excellent workability and printability. Furthermore, it was possible to provide an erasing method using the above erasing liquid.

Claims (3)

[Claims] (1) In an erasing solution for photosensitive planographic printing plates that does not require dampening water and contains at least a silicone rubber, a silane coupling agent, and a solvent, the solvent may be a paraffin hydrocarbon, isoparaffin hydrocarbon, cyclo An erasing liquid for photosensitive lithographic printing plates that does not require dampening water and is characterized by being a paraffinic hydrocarbon, an aromatic hydrocarbon, or a mixture thereof. (2) The erasing liquid according to claim 1, wherein the amount of the silane coupling agent added is 1 to 9% by weight based on the weight of the silicone rubber. (3) having at least a primer layer, a photosensitive layer, and a silicone rubber layer on the support in this order from the support side, the primer layer containing at least a hydroxyl group-containing polymer, a polymerizable monomer, and a photopolymerization initiator; Erasing a dampening water-free photosensitive lithographic printing plate, characterized in that a dampening water-free photosensitive lithographic printing plate whose layer contains at least a hydroxyl group-containing polymer and a diazo resin is treated with the erasing liquid according to claim 2. Method.