JPS63214757A - Method for making waterless planographic lithographic printing plate - Google Patents

Abstract

PURPOSE:To decolor a discolored part without degrading printing resistance by subjecting a waterless planographic printing plate formed by coating a photosensitive layer consisting of a material contg. quinone diazide structure as its constituting component and silicone rubber layer on a base to image exposure, then subjecting the plate to a base treatment simultaneously with or before or after development then processing the plate with a processing liquid contg. an org. acid. CONSTITUTION:For example, the ester of benzoquinone-1,2-diazide-4- or -5- sulphonic acid and polyhydroxyphenyl or the like is used as the quinone diazides. The silicone rubber layer essentially consisting of linear org. polysiloxane having the repeating unit such as the unit expressed by the formula I and having several thousands - several ten thousands mol.wt. is preferably used as the silicone rubber layer. In the formula, n: >=2 integer, R, R': an alkyl group of 1-10C, alkenyl group or phenyl group, >=60% of R, R' are preferably the methyl group. The printing plate is subjected to the basic treatment and the processing by the processing liquid contg. the org. acid after the image exposure or simultaneously therewith or before the image exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for making a waterless planographic printing plate, and particularly to a method for making a waterless planographic printing plate with excellent plate inspection properties.

[Prior Art] Various types of waterless lithographic printing plates comprising a photosensitive layer and a silicone rubber layer are known. Among these, negative and positive amphoteric type waterless lithographic printing can be achieved by base-treating an image forming laminate comprising a support, in which a photosensitive layer containing a substance containing a quinonediazide structure and a silicone rubber layer are provided in this order. The method to obtain the plate is published in Japanese Patent Application Laid-open No. 1983.
- As disclosed in No. 17552, the development latitude of waterless lithographic printing plates including image reproducibility, solvent resistance, developability, etc. can be expanded, and negative and positive plates can be made from the same plate material. It has excellent characteristics such as

Furthermore, Japanese Patent Laid-Open No. 60-28654 proposes a method of forming an image using water or a developer containing water as a main component after image exposure and base treatment, or simultaneously with base treatment. In addition, JP-A-57-205740, JP-A-60
169852 and JP-A-60-192948 disclose a method of imagewise exposure and base treatment before or after development to fix non-image areas.

In these conventional plate-making methods for waterless lithographic printing plates, when the base treatment is performed, the photosensitive layer in the non-image area changes color to brown, making it difficult to distinguish between the image area and the non-image area, resulting in poor plate inspection properties. It has disadvantages such as the image quality of the plate becomes poor due to the uneven decolorization of the plate and the like.

[Problems to be Solved by the Invention] As a result of intensive studies to solve these problems, the present inventors found that it is suitable to perform treatment with a treatment liquid containing an organic acid after base treatment. The invention has been achieved.

The purpose of the present invention is to improve printing durability, solvent resistance, and
An object of the present invention is to provide a plate-making method capable of decolorizing non-image areas that have been discolored to brown without reducing scratch resistance etc., and obtaining a waterless lithographic printing plate having excellent plate inspection properties.

[Means for Solving the Problems] That is, the present invention provides a waterless lithographic printing plate in which a photosensitive layer containing a substance containing a quinone diazide structure and a silicone rubber layer are coated in this order on a support. The present invention relates to a method for making a waterless lithographic printing plate, which is characterized in that imagewise exposure is performed, base treatment is performed at the same time as development, or before and/or after development, and then treatment is performed with a treatment solution containing an organic acid.

The support used in the present invention is not particularly limited, but any support that is used in ordinary waterless lithographic printing plates or that has been proposed may be used.

Examples include metal plates such as aluminum, iron, and zinc; transparent or opaque plastic films such as polyester, polyolefin, and polystyrene; and composites of both. It is also possible to further coat these sheets with a resin layer or the like for antihalation purposes or other purposes to form a support.゛The photosensitive layer referred to in the present invention is composed of a substance containing a known quinonediazide structure, and the substance containing a quinonediazide structure is a material normally used in positive-working PS plates, Wibon plates, photoresists, etc. These are quinonediazides.

Examples of such quinonediazides include esters of benzoquinone-1,2-diazide-4- or -5-sulfonic acid and polyhydroxyphenyl, naphthoquinone-1
, ester of 2-diazide-4- or -5-sulfonic acid and pyrogallolacetone resin, naphthoquinone-1,
Esters of 2-diazide-4- or -5-sulfonic acid and phenol formaldehyde novolac resins or cashew-modified novolak resins may be mentioned. Also, low amounts of quinonediazide compounds (e.g. naphthoquinone-1,2
esters of -diazide-5-sulfonic acid with phenol, talezol, xylenol, catechol, pyrogallol, bisphenol A, etc.) or novolak resins that do not contain photosensitive groups in the resins containing the quinone diazide group (e.g., phenol, A soluble resin (such as a soluble resin produced by condensing phenols such as cresol, xylenol, catechol, and pyrogallol with formaldehyde in the presence of an acidic catalyst) may be simply mixed. Furthermore, there may be mentioned a photoreleasable photosensitive layer in which quinone diazides are crosslinked with a polyfunctional compound as proposed in JP-A-56-80046.

As a crosslinking agent, polyfunctional isocyanates such as
paraphenylene diisocyanate, 2°4- or 2.
6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, inphorone diisocyanate or their adducts, or polyfunctional epoxy compounds such as polyethylene glycol diglycidyl ethers, Examples include polypropylene glycol diglycidyl ethers, bisphenol A diglycidyl ether, and trimethylolpropane triglycidyl ether. These thermal curing ranges within a range that does not cause loss of photosensitivity of the photosensitive material, usually 13
It is preferable to carry out the reaction at a temperature of 0° C. or lower, and therefore a catalyst or the like is usually used in combination.

In addition, methods for modifying quinonediazides by reacting with a monofunctional compound to make them poorly soluble or insoluble in developing solutions include esterifying, amidating, or urethanizing the active groups of the quinonediazides. can be mentioned. The compound to be reacted with the active group of the quinonediazide may be a low-molecular compound or a relatively high-molecular compound, or a monomer may be graft-polymerized to the quinonediazide.

Particularly preferable photosensitive layers for use in the present invention are:
It is obtained by crosslinking or modifying a partially esterified product of naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolak resin with a polyfunctional or monofunctional isocyanate.

The thickness of the photosensitive layer is about 0.1-100μ, preferably about 0.1μ.
5 to 10μ is appropriate. If it is too thick, defects such as pinholes are likely to occur during coating, while if it is too thick, it is disadvantageous from an economic standpoint.

Further, it is possible to add other components to the photosensitive layer for the purpose of improving coating film forming properties and adhesion to the support within a range that does not impair the effects of the present invention.

The silicone rubber layer used in the present invention is preferably one whose main component is a linear polysiloxane having several thousand to several hundreds of thousands of molecules having the following repeating units.

Here, n is an integer of 2 or more, and R and R' have 1 to 10 carbon atoms.
is an alkyl group, alkenyl group, or phenyl group, and those in which 60% or more of R and R' are methyl groups are preferred.

A crosslinking agent is usually added to this linear organic polysiloxane. Examples of crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane,
There are ketooxime silanes, alkoxysilanes, aminosilanes, amidosilanes, etc., which are usually used in combination with linear organic polysiloxanes with hydroxyl groups at the ends, to produce acetic acid-removed type, oxime-eliminated type, alcohol-eliminated type, deamined type, and deamidated type, respectively. It becomes the silicone rubber of the mold. A small amount of an organic tin compound or the like may be added as a catalyst to these silicone rubbers.

The appropriate thickness of the silicone rubber layer is about 0.5 to 100μ, preferably about 0.5 to 10μ; if it is too thin, problems may occur in terms of printing durability, while if it is too thick, it is not economical. Not only is this disadvantageous, but it also becomes difficult to remove the silicone rubber layer during development, resulting in a decrease in image reproducibility.

In the printing plate used in the present invention, a support, a photosensitive layer,
The adhesion between the photosensitive layer and the silicone rubber 1 is very important for basic plate performance such as image reproducibility and printing durability, so if necessary, an adhesive layer may be provided between each layer, or an adhesive layer may be provided between each layer. It is also possible to add improving components. In particular, it is effective to provide a known silicone primer or silane coupling agent layer between the eyebrows or add a silicone primer or silane coupling agent to the silicone rubber layer or photosensitive layer to improve the adhesive strength between the photosensitive layer and the silicone rubber layer. be.

A thin protective film can also be laminated on the surface of the waterless lithographic printing original plate constructed as described above.

The waterless lithographic printing plate precursor used in the present invention is produced, for example, as follows. First, a composition solution to form a photosensitive layer is applied onto a support using a normal coater such as a reverse roll coater, air knife coater, Meyer bar coater, or a spin coating device such as a whaler, and then dried and coated as necessary. After heat curing, if necessary, apply an adhesive layer on the photosensitive layer in the same manner, and after drying, apply a silicone gum solution on the photosensitive layer or the adhesive layer in the same manner, usually 50~ Heat treatment is performed at a temperature of 130° C. for several minutes to fully cure and form a silicone rubber layer. If necessary, cover the silicone rubber layer with a protective film using a laminator or the like.

When the waterless lithographic printing original plate thus obtained is subjected to image exposure using a positive film, a positive original image, or a negative film or a negative original image, and then developed, a waterless lithographic printing plate is obtained.

Examples of the plate-making method for such a waterless lithographic printing original plate include the following. For example, when used as a positive waterless lithographic printing original plate, 5 to 60 of the quinonediazide units of the substance containing the quinonediazide structure in the photosensitive layer are exposed to actinic light through a vacuum-adhered positive film or positive original.
By applying imagewise exposure such that a mole percent is photodegraded, and performing base treatment and development, a waterless lithographic printing plate is obtained.

On the other hand, when used as a negative waterless lithographic printing plate,
Through vacuum sealed negative film or negative original image,
After applying normal image exposure to actinic light (an exposure port in which more than 60 mol% of the quinonediazide units of the substance containing the quinonediazide structure in the photosensitive layer is photodecomposed), development after base treatment, development at the same time as base treatment, Alternatively, a waterless lithographic printing plate can be obtained by performing a base treatment after development. More preferably, the photosensitive layer in the non-image area, including the image area, is photodecomposed in such a way that 5 to 60 mol% of the quinonediazide units of the substance containing the quinonediazide structure in the photosensitive layer in the non-image area are photodecomposed before or after normal image exposure. After full exposure, development after base treatment,
It is preferable to perform the base treatment at the same time as the base treatment or after the development.

The light source used in this exposure process is one that generates abundant ultraviolet light, and can be a mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, or the like. In addition to ultraviolet light, laser light is also used.

Examples of the base treatment method used in the present invention include the following methods.

A, Negative type (1) Full surface exposure → Image exposure → Base treatment → Development (2) Image exposure → Full surface exposure → Base treatment → Development (3) Full surface exposure → Image exposure → Base treatment at the same time as development (4) Image exposure → Whole surface exposure → development and base treatment (5) whole surface exposure → image exposure → development → base treatment (6> image exposure → whole surface exposure → development → base treatment (7) image exposure → development → whole surface exposure → base treatment (8) Image exposure → development Base treatment 9> image exposure → base treatment → development Immerse it in a base treatment solution, or
Alternatively, the plate surface can be uniformly wetted with the processing liquid using a brush or pad, or it can be wetted using a shower method such as an automatic developing machine.

The treatment time is not particularly limited and depends on the strength of the base used and #!
Although it can be selected as appropriate depending on the degree of treatment, the effect usually appears immediately upon contact with the treatment liquid, and there is no change in the effect even if the treatment liquid is kept in contact for a long time. Usually it takes about 10 seconds to 5 minutes.

The bases used in the base treatment of the present invention include amine compounds (aliphatic chain amines, aliphatic cyclic amines, aromatic amines, heterocyclic amines, primary, secondary, tertiary amines, monoamines, diamines, triamines). , tetraamine,
polyamines, etc.). For example, ammonia, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine, trimethylamine, propylamine, butylamine, amylamine,
dipropylamine, dibutylamine, cyamylamine,
tripropylamine, triethylamine, methylbenzylamine, ethylenediamine, trimethylenediamine,
Tetramethylenediamine, polyethyleneimine, benzylamine, N,N-dimethylbenzylamine, N,N-
Diethylbenzylamine, N,N-dipropylbenzylamine, 0- or m- or p-methoxy or methylbenzylamine, N,N-di(methoxybenzyl)amine 1, β-phenylethylamine, ε, δ-phenyl Amylamine, γ-phenylpropylamine, cyclohexylamine, aniline, monomethylaniline, dimethylamine, toluidine, benzidine, α or β
- Naphthylamine, 0 or m- or p-phenylenediamine, pyrrolidine, piperidine, piperazine, morpholine, urothrobin, diazabicycloundecane, pyrrole, pyridine, quinoline, hydrazine, phenylhydrazine, N,N=-diphenylhydrazine, hydroxylamine, urea , semicarbazide, diourea, tetraalkylammonium hydroxide, monoethanolamine, N
-Methylethanolamine, N-ethylethanolamine, N-n-butylethanolamine, jetanolamine, triethanolamine, 2-(2-amineethyl)ethanol, 2-amino-2-methyl-1,3-propanediol , 2-amino-1,3-propadiol,
2-Amino-2-hydroxymethyl-1,3-propanediol, 3-hydroxypropylmethylamine, 4-
Hydroxybutylmethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 3-propoxypropylamine, 3-isopropoxypropylamine,
3-butoxypropylamine, 3-isobutoxypropylamine, 2-ethylhexyloxypropylamine, 2
-ethoxyethylamine, 2-propoxyethylamine, 2-butoxyethylamine, 2-(aminoethoxy)
Ethanol etc. are used.

These bases may be used alone or in a mixture, in liquid or gas phase. In liquid form, for example, the base itself,
Alternatively, it is used in the form of a solution.

When used as a solution, the solvent may be water, an organic solvent, or a mixed solution of both.

As the developer, those commonly proposed for waterless lithographic printing plates can be used. For example, water and water with the following polar solvent added are suitable.

Alcohols (methanol, ethanol, etc.), ethers (ethyl cellosolve, ethyl carpitol, butyl carpitol esters (cellosolve acetate, carpitol acetate, etc.)) It is also possible to directly develop with a base processing solution.

After the base treatment, treatment is performed with a treatment solution containing an organic acid. Examples of this method include the following method.

(1) Base treatment → development → treatment with organic acid (2) At the same time as development, base treatment → treatment with organic acid (3) Development → base treatment → Yes F! Treatment with a acid (4) Base treatment → Treatment with organic acid → Development The organic acid used after this base treatment is not particularly limited, but for example, carboxylic acid, sulfonic acid,
Any organic acid such as phosphonic acid may be used, but a preferred organic acid is a carboxylic acid having 2 to 18 carbon atoms and a boiling point of 140°C or higher. More preferably, it is a carboxylic acid having 2 to 18 carbon atoms and a boiling point of 160°C or higher. If the number of carbon atoms is less than 2 and the boiling point is lower than 140° C., the decolorizing property after treatment is sufficient, but if the plate is left to stand, color will develop, which is not preferable. On the other hand, if the number of carbon atoms exceeds 18, the effect on the photosensitive layer through the silicone rubber layer will be small and the decolorizing property will be lacking, which is not preferable.

Examples of the above-mentioned carboxylic acids having 2 to 18 carbon atoms and a boiling point of 140°C or higher include propionic acid, acetic acid, etc.
Carboxylic acids having 2 to 18 carbon atoms and a boiling point of 160°C or higher include isobutyric acid, n-valeric acid, isovaleric acid,
n-caproic acid, isocaproic acid, 2-methylpentanoic acid, 2-ethylbutyric acid, enanthic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, undecylic acid, undecylic acid, lauric acid, myristic acid, palmitic acid, oleic acid acid, stearic acid, chloroacetic acid, dichloroacetic acid,
Trichloroacetic acid, iodoacetic acid, fluoroacetic acid, trifluoroacetic acid, α-chloropropionic acid, β-chloropropionic acid, α-bromopropionic acid, α-bromobutyric acid, α
-bromoisobutyric acid, α-bromovaleric acid, α-bromoisovaleric acid, α-bromo-n-caproic acid, β-ethoxypropionic acid, maleic acid monoethyl ester, maleic acid mono-n-butyl ester, and the like.

The solvent used in the treatment liquid of the present invention includes water,
A polar solvent and a hydrocarbon can be used alone or in combination.

Alcohols (methanol, ethanol, n-propanol, isopropanol, 3-methoxybutanol, 3
-methyl-3-methoxybutanol, diacetone alcohol, etc.).

Ethers (dioxane, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol diethyl ether, diethylene glycol 7-methyl ether, diethylene glycol 7-methyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether) , triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tetrahydrofurfuryl alcohol, etc.).

Nisdels (methyl acetoacetate, ethyl acetoacetate, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether acetate, glycol diacetate, ethyl lactate, methyl propionate, ethyl propionate) , dimethyl malonate, dimethyl succinate, diethyl succinate, dimethyl adipate, etc.).

As hydrocarbons, those shown below are generally useful.

Aliphatic hydrocarbons (pentane, hexane, heptane, octane, gasoline, kerosene, light oil, heavy oil, “isopar”)
Aromatic hydrocarbons (toluene, xylene, etc.) such as E, H, M (manufactured by Exxon Chemical).

Halogenated hydrocarbons (triclene, carbon tetrachloride, etc.)
.

The amount of organic acid added to the processing solution is preferably 0.01 to 50% by weight based on the processing solvent, from the viewpoint of decolorizing the plate material, and more preferably 0.1 to 20% by weight. It is good to add it.

A surfactant can also be added to the treatment liquid to improve wettability and solubility of organic acids.

In addition, dyes such as Crystal Violet and Eisen Basic Cyanine 6GH (manufactured by Hodogaya Chemical Co., Ltd.) may be added to improve plate inspection properties.

As a processing method, the plate surface may be wetted by immersion in the processing solution of the present invention or by showering as in the case of an automatic processor.

The present invention will be explained in more detail below by way of examples.

The treatment time is not particularly limited and can be selected depending on the strength and concentration of the acid and the temperature of the treatment solution, but normally the treatment solution will decolorize immediately upon contact with it, and there will be no effect if left in contact for a long time. There is no change. Usually it takes about 5 seconds to 3 minutes.

The present invention will be explained in more detail with reference to Examples below.

[Example] Example 1, Comparative Example 1 The following primer composition was applied to an aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) with a thickness Q of 3 mm, and heat treated at 200°C for 2 minutes to form a 5μ thick primer layer. Established.

■Polyurethane resin (Sunbren LQ-T1331, manufactured by Sanyo Chemical Industries, Ltd.) 100 parts by weight ■Blocked isocyanate (Takenate B830, manufactured by Narita Pharmaceutical Co., Ltd.)
20 parts by weight ■ Epoxy phenol urea resin (SJ9372, manufactured by Kansai Paint Co., Ltd.) 8 parts by weight ■ Dimethylformamide 725 parts by weight Subsequently, the following photosensitive layer composition was applied thereon using a bar coater, and heated at 110°C. The photosensitive layer was dried in hot air for 1 minute to form a 2 μm thick photosensitive layer.

■Partial ester of naphthoquinone-1,2-diazide-5-sulfonic acid and phenol formaldehyde novolac resin (Nisumilite Resin PR50622 manufactured by Sumitomo Durez) (degree of esterification 25% by elemental analysis)
100 parts by weight ■ 4,4°-diphenylmethane diisocyanate 40 parts by weight ■ 0.2 parts by weight of dibutyltin diacetate ■ 4,4°
- Diethylaminobenzophenone 5 parts by weight ■ P-Toluenesulfone M O, 8 parts by weight ■ Tetrahydrofuran 800 parts by weight Next, a silicone rubber composition having the following composition was spin-coated on the photosensitive layer, and the temperature was 115°C, dew point 30'C13. A silicone rubber layer of 2.3 μm was formed by curing with moist heat for 5 minutes.

■Polydimethylsiloxane (molecular weight approx. 25,0OO1 terminal OH group) 100 parts by weight ■Vinyl tri(
methyl ethyl ketoxime) silane
8 parts by weight ■Jibdeltin diacetate 0
．． 1 part by weight ■γ-aminopropyltrimethoxysilane 0
．． 5 parts by weight ■ “Isopar” E (manufactured by Exxon Chemical Co., Ltd.) 1400
The overlapping part is attached to the laminate obtained as above, with a polypropylene film "Torefane" (manufactured by Toshiku Co., Ltd.) having a thickness of 10 μm.
were laminated using a calendar roller to obtain a waterless lithographic printing original plate.

A metal halide lamp (Idol Fin 2000 manufactured by Miyazaki Electric Co., Ltd.) was used on the original printing plate, and a UV meter (
Newly made from oak, light major type UV-402A
The entire surface was exposed for 6 seconds at an illuminance of 11 mw/cr&.

A negative film having a halftone image of 150 lines/inch was vacuum-adhered to the printing original plate obtained as described above, and imagewise exposed for 60 seconds from a distance of 1 m using the metal halide lamp described above.

Next, the "Trefan" from the exposed plate was peeled off.

Next, a waterless lithographic automatic developing machine (TWL-1160) was used.
Diethylene glycol/2-(2-amine ethoxy)ethanol-87/
A processing solution consisting of 13 (weight ratio) was placed in the developing tank, and water was placed in the developing tank. Furthermore, in the after-treatment tank, water/diethylene glycol monobutyl ether/2-ethylhexane I! (boiling point 2
24℃)/Crystal Violet=80/20/11
Add a treatment liquid consisting of 0.3 (weight ratio) and add 45% of the pretreatment liquid.
℃, development water temperature 25℃, erosion treatment liquid temperature 25℃, and conveyance speed 40cm/min. It was bleached to yellow before being sold online.

This printing plate was attached to an offset printing machine, and printing was performed using Toyo King Ultra TKU Aquares G Eye PL manufactured by Toyo Ink Co., Ltd. When the halftone dot reproducibility was evaluated, halftone dots ranged from 2 to 98%. Prints with very good reproduced images were obtained.

On the other hand, the waterless lithographic printing plate precursor produced as described above was subjected to full-surface exposure and image exposure in the same manner as above, and plate-making was performed using an automatic waterless lithographic developing machine containing no post-processing liquid. A waterless lithographic printing plate was obtained which turned brown when treated with a base, and was partially decolored, resulting in a printing plate with poor plate inspection properties.

Example 2 Phenol formaldehyde novolac resin (Nisumilite resin PR5 manufactured by Sumitomo Bakelite Co., Ltd.) with a degree of esterification of 44% was applied to a chemically treated aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.).
0235) naphthoquinone-1,2-diazide-5-sulfonic acid ester (ethanol soluble component 9.7% by weight)
, the degree of esterification is 3% by weight (quantified from IR spectrum)
After applying the dioxane solution, it was dried at 60° C. for 3 minutes to form a 1q photosensitive layer with a thickness of 1.2 μm. 4% by weight of γ-aminopropyltriethoxysilane (manufactured by UCC: A1100) based on the silicone composition was added to a 7% Isopar E solution of a silicone gum composition having the following composition on top of this photosensitive layer. After stirring, it was applied with a Whaler. After drying 12
Heat cured at 0℃, dew point 25℃ for 4 minutes to a thickness of 2.2μ
A silicone rubber layer was obtained.

■Polydimethylsiloxane (molecular weight approximately so, ooo, both terminal OH groups) 100 parts by weight ■Ethyltriacetoxysilane 5 parts by weight ■Dibutyltin diacetate 0.2 parts by weight Waterless lithographic printing original plate obtained as above A negative film having a halftone dot image of 150 lines/inch was vacuum-adhered to the film, and image exposure was carried out for 60 seconds from a distance of 1 m using the metal halide lamp used in Example 1. When the surface of the exposed plate is lightly rubbed with a developer consisting of ethanol/Isopar E = 80/20 (weight ratio), both the silicone rubber layer and the photosensitive layer are easily removed from the image-exposed area, resulting in chemical conversion. The treated aluminum surface was exposed, resulting in an image that faithfully reproduced the negative film.

Using a metal halide lamp, 1
11 mw/ayt with the UV meter of Example 1 at a distance of m
After exposure for 10 seconds under the illuminance of
When the photosensitive layer was treated with a base for 1 minute using a treatment solution consisting of 515 (weight ratio), the photosensitive layer turned brown. Then water/diethylene glycol monobutyl ether/caprylic acid (boiling point 24
When it was immersed for 30 seconds in a treatment solution consisting of (0°C) = 85/15/1 (weight ratio), it was decolored to the yellow color before plate making.

In order to check whether the solvent resistance of the base-fixed plate changes due to the base-treated processing solution containing organic acid, it was roughly heated for 1 m using the metal halide lamp described above.
After exposing the entire surface to light for 60 seconds from a distance of , the film was rubbed with a developing pad impregnated with a developer consisting of ethanol/"Isopar E"=80/20 (weight ratio). The silicone rubber layer in the non-image area was not damaged at all, and the fixing effect did not deteriorate at all.

[Effects of the Invention] The printing plate made according to the present invention can reliably decolorize a plate that has turned brown due to base treatment without deteriorating its properties such as solvent resistance, printing durability, and scratch resistance. Can be done. That is, by the method for making a waterless lithographic printing plate of the present invention, a waterless lithographic printing plate with excellent plate inspection properties can be obtained. In addition, uneven decoloring of the plate does not occur, and the image of the plate improves.

Claims (2)

[Claims] (1) After imagewise exposure of a waterless lithographic printing plate formed by coating a support with a photosensitive layer containing a substance containing a quinonediazide structure and a silicone rubber layer in this order, at the same time as development or before development. and/or a method for making a waterless lithographic printing plate, characterized in that it is then subjected to a base treatment and then treated with a treatment liquid containing an organic acid. (2) The method for making a waterless lithographic printing plate according to claim (1), wherein the organic acid is a carboxylic acid having 2 to 18 carbon atoms and a boiling point of 140° C. or higher.