JPH11301135A - Manufacture of photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently improve erasing properties of a photosensing layer in a correcting step and to also improve an easy contamination of a non-image part. SOLUTION: The method for manufacturing a photosensitive lithographic printing plate comprises the steps of anodizing an aluminum or its alloy plate to form an oxide film, then hole sealing it, and thereafter providing a photosensing layer thereon by using a support for the lithographic printing plate obtained by treating it with an alkali metal silicate aqueous solution. The hole sealing is executed by a boiling water treatment or a pressurized steam treatment. In the case of hole sealing, a concentration of the alkali metal silicate aqueous solution is 0.001 to 0.2 wt.%, and a dipping temperature of the solution is 5 to 50 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a photosensitive lithographic printing plate. More specifically, the present invention relates to a method for producing a photosensitive lithographic printing plate which has improved erasability and does not deteriorate the stain performance caused by fingerprint marks and the stain performance caused by easy dispensing of ink during printing.

[0002]

2. Description of the Related Art A lithographic printing plate is obtained by imagewise exposing a photosensitive lithographic printing plate obtained by coating a photosensitive composition in a thin layer on aluminum or an alloy thereof (hereinafter simply referred to as "aluminum plate"). It is obtained by post-development. The aluminum plate is usually subjected to a surface roughening treatment such as a mechanical method such as a brush grain method or a ball grain method, an electrochemical method such as an electrolytic grain method, or a method combining the both,
After its surface is made matte, it is etched with an aqueous solution of an acid or alkali, and further subjected to anodic oxidation treatment, and then, if desired, is subjected to a hydrophilic treatment to form a support for a lithographic printing plate. A photosensitive lithographic printing plate (so-called PS plate) is provided with a photosensitive layer made of a photosensitive composition.

As the photosensitive composition, those comprising an o-quinonediazide compound are widely used. Such a photosensitive substance is used alone or mixed with an alkali-soluble resin such as a novolak type phenol resin or cresol resin to form a mixture on a support. Is painted on. When a support having a hydrophilic surface is used, the exposed portion is decomposed by the o-quinonediazide compound and changes to alkali-soluble, so that the exposed portion is easily removed with an alkali developing solution to expose the hydrophilic surface of the support. Accepts water and repels ink. On the other hand, unexposed portions remaining as images are lipophilic and accept ink. This PS version is
Usually, a lithographic printing plate is subjected to image exposure, development, correction, and gumming steps, and is mounted on a printing press for printing.

In the process of making a photosensitive lithographic printing plate, generally, a step of providing a photosensitive layer on an anodized aluminum plate, a step of exposing the photosensitive layer through a transparent original film, and a step of developing an exposed portion of the photosensitive layer are performed. The developing step of dissolving and removing with a liquid, after the developing step, remains on the anodized aluminum plate as a support due to insufficient exposure due to the edge portion of the original film or dust attached thereto, There is a correction step of erasing the photosensitive layer that should be removed with an erasing liquid. In this correction process, the length of time required for the photosensitive layer to be erased to be dissolved and erased with the erasing liquid is called erasability. If the erasure is performed in a short time, the erasability is excellent. It is described as poor erasability. If the erasability can be improved, the repair work can be completed in a short time, leading to an increase in work efficiency.

As a method for improving the erasability in the above-mentioned repairing process,
Conventionally, sealing treatment of the anodic oxide film on the support with hot water or steam, treatment of the anodic oxide film on the support with nitrite (Japanese Patent Application Laid-Open No. 5-10989), and treatment with an inclusion compound (Japanese Patent Application Laid-Open No. 8-106157) And the like are reported. However, in these conventional erasability improving methods, the non-image area after removing the positive photosensitive layer is easily stained,
In particular, when the fatigued developer is reused in the developing step, there is a problem that the stain on the non-image area becomes remarkable.

On the other hand, as a method of treating with a metal salt of an aliphatic monocarboxylic acid, a method disclosed in Japanese Patent Publication No. 7-90669 is known. In this method, a high temperature of 80 to 95 ° C. is used for 1 to 2 minutes. The purpose of this treatment is to improve the adhesion to the photosensitive layer by forming a fine structure on the surface of the anodic oxide film. With such a support, the erasability is improved, but the stain on the non-image area during printing is significantly deteriorated. Resulting in.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for sufficiently improving the erasability of a photosensitive layer in a repairing step and also improving the easiness of staining of a non-image area. .

[0008]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and found that after forming an anodized film on an aluminum or aluminum alloy plate by anodizing treatment and performing sealing treatment, By using a support immersed in an aqueous alkali metal silicate solution, the above object can be achieved.

The reason why the erasability of the photosensitive layer is sufficiently improved and the easiness of staining of the non-image area is also improved by performing such a process is considered as follows. That is, the micropores present in the anodic oxide film on the support are appropriately sealed by a sealing treatment to suppress penetration of the photosensitive layer, promote dissolution and removal of the photosensitive layer by an erasing liquid, and improve erasability. . On the other hand, the disadvantage that the non-image area is easily stained due to the fine structure formed on the outermost surface of the support by the sealing treatment is treated with an alkali metal silicate aqueous solution to form a necessary and sufficient silicate layer. As a result, the stain resistance can be improved without deteriorating other printing performance.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[Aluminum Support] The aluminum support used in the present invention is a dimensionally stable metal containing aluminum as a main component, and is made of aluminum or an aluminum alloy. In addition to pure aluminum plates, alloy plates containing aluminum as a main component and containing trace amounts of foreign elements,
Alternatively, it is selected from a plastic film or paper on which aluminum (alloy) is laminated or evaporated. Further, a composite sheet in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in JP-B-48-18327 may be used.

In the following description, the above-mentioned plates made of aluminum or aluminum alloy are collectively referred to as aluminum plates. The different elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium, and the like.
The content of the foreign element in the alloy is 10% by weight or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to produce due to smelting technology, and therefore may contain a slightly different element. As described above, the composition of the aluminum plate applied to the present invention is not specified.
IS A 1050, JIS A 1100, JIS A 3
103, JIS A 3005, etc. can be used as appropriate.

The aluminum plate used in the present invention is usually processed while continuously running in the form of a web, and has a width of about 400 mm to 2000 mm and a thickness of about 0.2 mm.
It is about 1 mm to 0.6 mm. The thickness printer can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's request.

The aluminum plate is appropriately subjected to a substrate surface treatment described later.

[Graining] The graining method includes mechanical graining, chemical etching and electrolytic graining as disclosed in JP-A-56-28893. Furthermore, an electrochemical graining method in which the aluminum surface is electrochemically grained in a hydrochloric acid or nitric acid electrolyte, a wire brush graining method in which the aluminum surface is scratched with a metal wire, and a ball graining method in which the aluminum surface is grained with a polishing ball and an abrasive. Alternatively, a mechanical graining method such as a brush grain method for graining the surface with a nylon brush and an abrasive can be used, and the above graining methods can be used alone or in combination.

Among them, a method of producing a surface roughness usefully used in the present invention is an electrochemical method of chemically graining in a hydrochloric acid or nitric acid electrolyte, and a suitable amount of electricity is 5%.
0 to 400 C / dm ² , preferably 100 to 300 C / dm ²
dm ² . More specifically, 0.01 to 5
In an electrolyte containing 0% by weight, preferably 0.5 to 10% by weight of hydrochloric acid or nitric acid, at a temperature of 20 to 100 ° C, preferably 30 to 70 ° C, for a time of 1 second to 30 minutes, preferably 2 seconds to 1 hour.
Min, current density 1 to 400 A / dm ² , preferably 10 to
It is preferable to perform electrolysis under the condition of 50 A / dm ² .

The aluminum plate thus grained is chemically etched with an acid or an alkali. When an acid is used as an etching agent, it takes time to destroy a fine structure, which is disadvantageous in industrially applying the present invention. However, it can be improved by using an alkali as an etching agent.

The alkaline agent preferably used in the present invention includes caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. 1 to 50% by weight, especially 2 to 20% by weight, 20 to 10%
0 ° C., especially 30-70 ° C., and the amount of Al dissolved is 0.1
The conditions are preferably such that the concentration is 〜20 g / m ² , particularly 0.3 to ² g / m ² .

After the etching, pickling is performed to remove dirt (smut) remaining on the surface. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borofluoric acid and the like are used. In particular, as a method for removing the smut after the electrochemical surface-roughening treatment, it is preferable to use a method of removing 50 to 50 as described in JP-A-53-12739.
A method of contacting with sulfuric acid of 15 to 65% by weight at a temperature of 90 ° C. and a method of alkali etching described in Japanese Patent Publication No. 48-28123 are exemplified.

[Anodizing treatment] The aluminum plate treated as described above is subjected to anodizing treatment. The anodizing treatment can be performed by a method conventionally performed in this field. Specifically, sulfuric acid, phosphoric acid, oxalic acid,
And the like are mainly used as an electrolytic bath. Depending on the case, chromic acid, sulfamic acid, benzenesulfonic acid, or the like, or an aqueous solution or a non-aqueous solution combining two or more of these may be used. An anodic oxide film can be formed on the surface of the aluminum support by applying a direct current or an alternating current to aluminum in the electrolytic bath as described above.

The conditions of the anodic oxidation treatment vary depending on the electrolytic solution to be used, and thus cannot be unconditionally determined. Generally, the concentration of the electrolytic solution is 1 to 80% by weight, preferably 5 to 80% by weight.
20% by weight, liquid temperature 5 to 70 ° C, preferably 10 to 60
° C, current density 0.5 to 60 A / dm ² , preferably 1 to
30 A / dm ² , voltage 1 to 100 V, preferably 5 to 5
The range of 0 V and the electrolysis time of 1 to 100 seconds, preferably 5 to 60 seconds are appropriate.

Among these anodizing treatments, those described in British Patent No. 1,412,768 are particularly useful.
The method of anodizing at a high current density in sulfuric acid and the method of anodizing phosphoric acid as an electrolytic bath described in US Pat. No. 3,511,661 are preferred.

In the present invention, the anodic oxide film has a thickness of 1-1.
It is preferably 0 g / m ² , and if it is 1 g / m ² or less, the plate is easily damaged, and if it is 10 g / m ² or more, a large amount of power is required for production, which is economically disadvantageous. Preferably, it is 1.5 to 7 g / m ² . More preferably, 2-5
g / m ² .

[Sealing treatment] After forming the anodic oxide film,
The micropores of the anodic oxide film are sealed by immersion treatment with boiling water or pressure steam treatment. Processing temperature is 1
The temperature is preferably about 00 to 200 ° C, preferably about 100 to 150 ° C, and the treatment time is about 5 to 60 seconds at 100 ° C.
At 50 ° C., the time is preferably about 1 to 30 seconds. There are many known examples of the above-mentioned sealing method, and for example, there is JP-A-4-176690. In the present invention, when the anodic oxide film after the sealing treatment is observed at a magnification of 10,000 to 50,000 times by SEM, a large number of projections considered to be boehmite are observed, while the surface area per unit geometric area is determined by BET.
When measured by the one-point method, 5 to 50% before sealing, particularly 5%
It is desirable that the state is reduced to about 30%.

[Alkali metal silicate treatment] The anodic oxide film of the aluminum plate sealed as described above is immersed in an alkali metal silicate aqueous solution. The concentration of the alkali metal silicate is suitably about 0.001 to 0.2 wt.%, And preferably about 0.01 to 0.1 wt.%. The treatment temperature is preferably 5 to 50 ° C. for 1 to 60 seconds.
Then, it is washed with running water. More preferably, the immersion temperature is 10 to 40C and the immersion time is 2 to 20 seconds. As the alkali metal silicate used in the present invention, sodium silicate, potassium silicate, lithium silicate and the like are used. Sodium hydroxide,
An appropriate amount of potassium hydroxide, lithium hydroxide or the like may be added. In addition, an alkaline earth metal salt or a Group IVB metal salt may be blended with the above treatment liquid. Examples of the alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate and barium nitrate, and aqueous solutions of sulfates, hydrochlorides, phosphates, acetates, oxalates, borates and the like. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, potassium titanium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, zirconium tetrachloride, and the like. Can be mentioned. Alkaline earth metal salts or I
The VB group metal salt can be used alone or in combination of two or more.

A photosensitive layer is provided on the aluminum plate which has been subjected to the above treatment, and a hydrophilic undercoat layer may be provided if necessary.

[Hydrophilic undercoat layer] A preferred hydrophilic undercoat layer used in the present invention is described in JP-A-60-1494.
No. 91, comprising a compound having at least one amino group and at least one group selected from the group consisting of a carboxyl group and a salt group thereof, and a sulfo group and a salt group thereof. Hydrophilic layer, JP-A-60-23
A hydrophilic layer comprising a compound selected from a compound having at least one amino group and at least one hydroxyl group and a salt thereof disclosed in Japanese Patent Application Laid-Open No. Sho.
No. 19494, a hydrophilic layer containing a phosphate, and a polymer compound containing at least one monomer unit having a sulfo group disclosed in JP-A-59-101651 as a repeating unit in the molecule A hydrophilic layer consisting of R ¹ (PO (OH) ₂ ) _n or R ^1- (PO (OH) (R ² )) _n disclosed in JP-A-4-282637. A substituted aliphatic compound or aromatic compound (n is 1 or 2, and when n = 1, R ¹ , R ²
A substituted or unsubstituted alkyl group, an alkoxy group, an aryloxy group, an aryl group, an acyl group, an acyloxy group, when n = 2, R ¹ represents a substituted or unsubstituted alkylene group or an arylene group, R ² Is as defined above).
Organic layers containing certain compounds are included. An appropriate amount of application is about 0.1 to 100 mg / m ² .

[Photosensitive layer] As the composition of the photosensitive layer used in the present invention, any composition can be used as long as its solubility or swelling property in a developing solution before and after exposure changes. Hereinafter, representative ones will be described.

Examples of the photosensitive compound of the positive photosensitive composition include an o-quinonediazide compound, and a representative example thereof is an o-naphthoquinonediazide compound.

The o-naphthoquinonediazide compound is preferably an esterified compound of 1,2-diazonaphthoquinonesulfonic acid chloride and pyrogallol-acetone resin described in JP-B-43-28403. Other suitable o-quinonediazide compounds include U.S. Pat. Nos. 3,046,120 and 3,18.
There is an ester of 1,2-diazonaphthoquinone sulfonic acid chloride and phenol-formaldehyde resin described in U.S. Pat. No. 8,210. Other useful o
-Naphthoquinonediazide compounds include those reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802,
No. 48-63803, No. 48-96575, No. 49
No. 38701, No. 48-13354, Japanese Patent Publication No. 37-
No. 18015, No. 41-11222, No. 45-961
Nos. 0 and 49-17481, U.S. Pat.
No. 97,213, No. 3,454,400, No. 3,
Nos. 544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602 and 1,251,34.
No. 5, No. 1,267,005, No. 1,329,88
No. 8, No. 1, 330, 932, German Patent No. 85
No. 4,890 and the like can be mentioned.

An o-naphthoquinonediazide compound obtained by reacting a polyhydroxy compound having a molecular weight of 1,000 or less with 1,2-diazonaphthoquinonesulfonic acid chloride can also be used. Specific examples of such compounds are described in JP-A-51-139402 and JP-A-58-15094.
No. 8, No. 58-203434, No. 59-165053
No., No. 60-112445, No. 60-134235
No., No. 60-163443, No. 61-118744
Nos. 62-10645, 62-10646, 62-153950, 62-178562, and 6
4-76047, U.S. Pat. No. 3,102,809,
No. 3,126,281, No. 3,130,047
No. 3,148,983 and No. 3,184,310
No. 3,188,210 and No. 4,639,406
No. and other publications or specifications.

When synthesizing these o-naphthoquinonediazide compounds, it is preferable to react 0.2 to 1.2 equivalents of 1,2-diazonaphthoquinonesulfonic acid chloride with respect to the hydroxy group of the polyhydroxy compound.
More preferably, the reaction is performed in an amount of 0.3 to 1.0 equivalent.
As the 1,2-diazonaphthoquinonesulfonic acid chloride, 1,2-diazonaphthoquinone-5-sulfonic acid chloride is preferable, but 1,2-diazonaphthoquinone-4-chloride is preferred.
Sulfonyl chloride can also be used.

The resulting o-naphthoquinonediazide compound is a mixture of various 1,2-diazonaphthoquinonesulfonate groups having different positions and amounts of 1,2-diazonaphthoquinonesulfonate ester groups. The ratio of the compound converted to the above to the mixture (the content of the completely esterified compound) is preferably 5 mol% or more, more preferably 20 to 99 mol%.

As the photosensitive compound which acts positively without using an o-naphthoquinonediazide compound, for example, a polymer compound having an o-nitrocarbinol ester group described in JP-B-56-2696 is also included in the present invention. Can be used.

A compound that generates an acid by photolysis,
-CO-C- group or -CO-Si dissociated by acid
A combination system with a compound having a group can also be used in the present invention.

For example, a combination of a compound capable of generating an acid by photolysis with an acetal or an O, N-acetal compound (Japanese Patent Application Laid-Open No. 48-89003), a combination with an orthoester or amide acetal compound (Japanese Patent Application Laid-Open No. 1
20714), a combination with a polymer having an acetal or ketal group in the main chain (JP-A-53-13342).
No. 9), a combination with an enol ether compound (JP-A-55-12995), a combination with an N-acylimino carbon compound (JP-A-55-126236),
Combination with a polymer having an orthoester group in the main chain (JP-A-56-17345), combination with a silyl ester compound (JP-A-60-10247) and combination with a silyl ether compound (JP-A-60-17247) 60-375
49, JP-A-60-112446) and the like.

The amount of these positive-acting photosensitive compounds (including the above combinations) in the photosensitive composition of the present invention is suitably from 10 to 50% by weight, and more preferably from 15 to 50% by weight. 40% by weight.

Although the o-quinonediazide compound alone can form the photosensitive layer, it is preferably used together with a resin soluble in alkaline water as a binder. Such resins soluble in alkaline water include novolak resins having this property, such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, and m- / p.
-Mixed cresol formaldehyde resin, phenol /
Cresol (may be m-, p-, or m- / p-mixed) Cresol formaldehyde resin such as mixed formaldehyde resin, phenol-modified xylene resin, polyhydroxystyrene, polyhalogenated hydroxystyrene, JP-A-51-34711 Acrylic resin containing a phenolic hydroxyl group as disclosed in
Various alkali-soluble polymer compounds such as an acrylic resin having a sulfonamide group described in JP-A-2-866 and a urethane-based resin can be contained.
These alkali-soluble polymer compounds have a weight average molecular weight of 500-20,000 and a number average molecular weight of 200-6.
000 is preferred.

Such an alkali-soluble polymer compound is used in an amount of not more than 70% by weight of the total composition.

Further, as described in U.S. Pat. No. 4,123,279, a compound having an alkyl group having 3 to 8 carbon atoms as a substituent, such as a t-butylphenol formaldehyde resin and an octylphenol formaldehyde resin. It is preferable to use a condensate of phenol and formaldehyde or an o-naphthoquinonediazidosulfonic acid ester of these condensates (for example, those described in JP-A-61-243446) in order to improve the oil sensitivity of an image. .

In the photosensitive composition of the present invention, a cyclic acid anhydride for enhancing sensitivity, a printing-out agent for obtaining a visible image immediately after exposure, a dye or other filler as an image coloring agent, and the like are included. Can be added. The cyclic acid anhydride U.S. Pat phthalic anhydride as described in 4,115,128 Pat, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-oxy - [delta ⁴ -
Examples include tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, and pyromellitic anhydride. By containing these cyclic anhydrides in an amount of 1 to 15% by weight based on the total weight of the composition, the sensitivity can be increased up to about three times. As a printing-out agent for obtaining a visible image immediately after exposure, a combination of a photosensitive compound that releases an acid upon exposure and an organic dye capable of forming a salt can be exemplified.

Specifically, o-type compounds described in JP-A-50-36209 and JP-A-53-8128 are disclosed.
Combinations of naphthoquinonediazide-4-sulfonic acid halide and salt-forming organic dyes and JP-A-53-36223, JP-A-54-74728, JP-A-60-3626, and JP-A-61-1
No. 43748, No. 61-151644, No. 63-58
No. 440, and combinations of trihalomethyl compounds and salt-forming organic dyes. Other dyes besides the above-mentioned salt-forming organic dyes can be used as image coloring agents. Suitable dyes, including salt-forming organic dyes, include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 130, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 60
3. Oil black BY, oil black BS, oil black T-505 (all manufactured by Orient Chemical Industries, Ltd.), Victoria Pure Blue, crystal violet (CI142555), ethyl violet (CI
42600), methyl violet (CI42535),
Rhodamine B (CI45170B), malachite green (CI42000), methylene blue (CI5201)
5) and the like. Also, JP-A-62-29
The dyes described in 3247 are particularly preferred.

In the present invention, the photosensitive composition is dissolved in a solvent capable of dissolving each of the above-mentioned components and coated on a support. As the solvent used here, ethylene dichloride, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, toluene , Ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, dimethylacetamide,
Examples include dimethylformamide, water, N-methylpyrrolidone, tetrasdrofluryl alcohol, acetone, diacetone alcohol, methanol, ethanol, isopropanol, diethylene glycol, and dimethyl ether. These solvents are used alone or in combination. The concentration (solid content) of the above components in the solution is 2 to 50.
% By weight. The coating amount varies depending on the application, but for example, in the case of a photosensitive lithographic printing plate, the solid content is generally preferably 0.5 to 3.0 g / m ² . As the amount of coating decreases, the photosensitivity increases, but the physical properties of the photosensitive film deteriorate.

In the photosensitive composition of the present invention, a surfactant for improving coating properties, for example, JP-A-62-1
A fluorine-based surfactant as described in JP-A-70950 can be added. A preferable addition amount is 0.01 to 1% by weight, more preferably 0.05 to 0.5% by weight of the whole photosensitive composition.

The thickness of the photosensitive layer can be 0.1 to 30 μm, more preferably 0.5 to 10 μm. The amount of the photosensitive layer provided on the support (fixed frequency) from about 0.1 to about 7 g / m ^2, preferably in the range of 0.5-4 g / m ^2. The surface of the photosensitive layer provided as described above is preferably matted in order to shorten the time for evacuation during contact exposure using a vacuum printing frame and to prevent printing blur. Specifically, a method of providing a mat layer as described in JP-A-50-125805, JP-B-57-6582 and JP-B-61-28986 is described in JP-B-62-62337. And a method of thermally fusing such a solid powder. After the imagewise exposure of the photosensitive lithographic printing plate of the present invention, the lithographic printing plate is made into a lithographic printing plate by a process including development by a conventional method.

In the case of a positive type lithographic printing plate, after image exposure,
U.S. Pat. No. 4,259,434 and JP-A-3-903.
By developing with an alkaline aqueous solution as described in JP-A-88-88, the exposed portion of the photosensitive layer is removed to obtain a lithographic printing plate.

The photosensitive lithographic printing plate of the present invention is disclosed in
JP-A-8002, JP-A-55-115045 and JP-A-59-15045.
It goes without saying that the plate-making process may be performed by the method described in each of the publications of No. 58431. That is, after the development processing,
A desensitization treatment after washing with water, a desensitization treatment as it is, a treatment with an aqueous solution containing an acid, or a treatment with an aqueous solution containing an acid may be followed by a desensitization treatment. Furthermore, in the development process of this type of photosensitive lithographic printing plate, the alkali aqueous solution is consumed depending on the processing amount, and the alkali concentration is reduced, or the alkali concentration is reduced by air due to long-time operation of the automatic developing solution. The processing capacity is reduced. At this time, a fresh unused developer (replenisher) is added, or processing is performed using a replenisher having a high alkalinity as described in JP-A-54-62004. You may restore your abilities. In this case, a method of adding a replenisher in an amount proportional to the length of one piece of the PS plate to be processed or US Pat.
It is preferred to replenish by the method described in US Pat. No. 2,246.

The plate making process described above is disclosed in
It is preferably carried out using an automatic developing machine as described in JP-A-7054 and JP-A-2-32357.

In the case where the photosensitive lithographic printing plate of the present invention is subjected to image exposure, development, washing or rinsing, and then unnecessary image portions are erased, it is described in JP-B-2-13293. It is preferable to use such an erasing liquid. Examples of the desensitized gum which is applied as required in the final step of the plate making process include JP-B-62-16834, JP-B-62-25118, JP-B-63-52600 and JP-A-6-52600.
Nos. 2-7595, 62-11693 and 62-83
What is described in each gazette of No. 194 is preferable.

Further, when the photosensitive lithographic printing plate of the present invention is subjected to image exposure, development, washing or rinsing, erasing if desired, and rinsing after washing with water, the burning is carried out before burning. No. 2518, 55-2806
No. 2, JP-A Nos. 62-31859 and 61-15965.
It is preferable to carry out treatment with a surface-regulating liquid as described in each publication of No. 5.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[0052]

EXAMPLE An aluminum plate having a thickness of 0.30 mm was grained with a nylon brush and an aqueous suspension of 400 mesh pumistone, and then thoroughly washed with water. 10
After immersion in 70% sodium hydroxide at 70 ° C. for 60 seconds, etching, washing with running water and neutralization washing with 20% HNO ₃ ,
Washed with water. This was subjected to electrolytic surface roughening treatment in a 1% nitric acid aqueous solution at an anode-time electricity quantity of 260 coulomb / dm ² using a sine wave alternating current under the condition of _VA = 12.7 V.
When the surface roughness was measured, it was found to be 0.55μ (Ra display).
Met. Subsequently, the sample was immersed in a 30% aqueous solution of H ₂ SO _{4 and} desmutted at 55 ° C. for 2 minutes.
The substrate was prepared by anodizing in a H ₂ SO ₄ aqueous solution at a current density of 5 A / dm ² for 45 seconds.

Thereafter, the substrate was subjected to sealing treatment and alkali metal treatment under the conditions shown in (Table 1), washed with running water and dried, and then coated with the next photosensitive solution by rod coating at 25 ml / ml.
m ^{2, and} dried at 100 ° C. for 1 minute to obtain a positive photosensitive lithographic printing plate. The coated amount after drying was about 1.5 g / m ² .

[Photosensitive solution] Esterified product of 1,2-diazonaphthoquinone-5-sulfonyl chloride and pyrogallol-acetone resin (as described in Example 1 of US Pat. No. 3,635,709) 0.90 g phenol / p-cresol aldehyde resin having a weight average molecular weight of 8000 (phenol / p-cresol molar ratio: 5/5, containing 0.7% g of unreacted cresol) 1.60 g m-cresol -Formaldehyde novolak resin (weight average molecular weight 1,700, number average molecular weight 600, containing 1% of unreacted cresol) 0.3 g P-normal octylphenol-formaldehyde resin (U.S. Pat. No. 4,123,279) 0.02 g naphthoquinonediazide-1,2-diazide-4-sul Phosphonic acid chloride 0.01 g Tetrahydrophthalic anhydride 0.02 g Dye in which the counter anion of Victoria Pureable-BOH [manufactured by Hodogaya Chemical Co., Ltd.] is changed to 1-naphthalenesulfonic acid 0.05 g Megafac F-176 (Dainippon) Ink Chemical Industry Co., Ltd. fluorine surfactant) 0.01 g methyl ethyl ketone 55 g

Based on the method described in Example 1 of Japanese Patent Publication No. Sho 61-28986, on the plate coated in this manner, a mixture of (methyl methacrylate / ethyl acrylate / sodium acrylate: 68/20/12) A mat layer was provided by dissolving 0.1 g of tartrazine in 100 g of the aqueous copolymer solution and electrostatically spraying.

Using the photosensitive lithographic printing plate thus obtained as a light source, a 2KW metal halide lamp (Idolfin 20000 manufactured by Iwasaki Electric Co., Ltd.) was used to obtain a Fuji Photo Film.
The exposure time was adjusted with a step guide manufactured by Co., Ltd. so as to clear four steps. After the exposure, the planographic image quality of the printing plate was visually evaluated, and then a 5.26% aqueous solution of sodium silicate having a molar ratio of SiO ₂ / Na ₂ O of 1.74 (PH) was used as a developer.
= 12.7), and passed through a stublon 900D, an automatic developing machine manufactured by Fuji Photo Film Co., Ltd., charged with FP-2W (1: 1) manufactured by Fuji Photo Film Co., Ltd. as a finisher liquid.

Table 1 shows the results of the evaluation of the erasability and the print smear of the obtained sample, and the results of measuring the contact angle of water droplets in oil and the surface area per unit geometric area of the non-image area after development.

<Measurement Method> Erasability: The image area of the printing plate after development was dissolved with an erasing solution (erasing solution RP-2 manufactured by Fuji Photo Film Co., Ltd.) until the photosensitive layer appeared to be completely removed. Time (time during which the remaining photosensitive layer in the image area cannot be completely discriminated) Print smear: When water supply and paper feed are started simultaneously with the printing plate attached to the offset printing machine and ink applied to the entire surface of the plate, Initially, ink adheres to the portion corresponding to the non-image portion on the printed matter and becomes stained, but as printing progresses, the ink is removed and eventually the original non-image where the ink does not adhere to the printed matter. Department. The number of damaged sheets up to this state is used as an index of print stain.

[0059]

[Table 1]

[0060]

According to the present invention, it is possible to obtain a photosensitive lithographic printing plate having excellent erasability in the repairing step and excellent stain performance of the non-image area.

Claims (4)

[Claims] Anodizing an aluminum or alloy plate thereof to form an oxide film, followed by sealing treatment, and then using a lithographic printing plate support obtained by treatment with an alkali metal silicate aqueous solution, A method for producing a photosensitive lithographic printing plate, comprising providing a photosensitive layer thereon. 2. The method for producing a photosensitive lithographic printing plate according to claim 1, wherein the sealing treatment is performed by boiling water treatment or pressurized steam treatment. 3. The method for producing a photosensitive lithographic printing plate according to claim 2, wherein the concentration of the aqueous alkali metal silicate solution is 0.001 to 0.2 wt%. 4. The method for producing a photosensitive lithographic printing plate according to claim 3, wherein the immersion temperature in the aqueous alkali metal silicate solution is 5 to 50 ° C.