JPH04148991A - Positive type photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To strongly and closely bond an image part to a support and to make coloration hard to generate in a non-image part by providing a hydrated oxide film to the surface of an aluminum plate aluminum plate to anodic oxidation in a sulfuric acid electrolyte to prepare a support and providing. a photosensitive layer containing o-quinone diazide on the support. CONSTITUTION:In order to remove the rolling oil on the surface of an aluminum plate, for example, the aluminum plate is subjected to degreasing treatment using a surfactant or an alkaline aqueous solution and graining treatment prior to anodic oxidation to provide a hydrated oxide film on the treated surface of the aluminum plate. The hydrated oxide film is formed by immersing the aluminum plate in hot water and the pref. temp. of the hot water is appropriately selected within the range of 50-100 deg.C. The treated surface is subsequently subjected to anodic treatment. The amount of the anodic oxide film is pref. 1-6g/m<2>. A positive type photosensitive diazo compound layer containing a o-quinone diazide is provided to the surface thus provided with one anodic oxide film. It is pref. to use the o-quinone diazide compound in the state mixed with an alkali-soluble resin. As the pref. alkali-soluble resin, a novolac type phenol resin is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photosensitive lithographic printing plate (PS plate) in which a photosensitive layer is provided on an aluminum support. More specifically, the present invention relates to a positive photosensitive lithographic printing plate that can be easily developed without dyeing non-image areas.

[Conventional technology]

In general, aluminum supports used in lithographic printing plates are required to have excellent hydrophilicity and water retention, and for this purpose, it is well known that they must be grained by mechanical, chemical, or electrochemical methods. It is being Furthermore, in order to increase the mechanical strength of this grained surface, it is known to anodize the surface in order to further increase water retention. Usually, a support is used which is provided with an anodic oxide film of about 2 g/i to 5 g/rd, has good water retention, and has a high surface mechanical strength.

If a positive PS plate is prepared by providing a positive photosensitive layer containing 0-quinonediazide on the surface, there is a problem that non-image areas become colored after development. In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 57195697 proposes treatment with condensed arylsulfonic acid I.lium. According to this method, it is possible to prevent coloring of two consecutive non-image areas, but on the other hand, there is a drawback that printing durability is reduced.

[Invention or problem to be solved]

Accordingly, an object of the present invention is to provide a positive-working photosensitive lithographic printing plate in which the image area is firmly adhered to the support and the non-image area is less likely to be colored.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the inventors of the present invention provided a hydrated oxide film on a grained aluminum surface and then anodized it in a sulfuric acid electrolyte. - It has been discovered that the above object can be achieved by providing a photosensitive layer containing quinonediazide, and the present invention has been completed.

Hereinafter, the present invention will be explained in detail step by step.

The aluminum plate used in the present invention is a plate-like body of pure aluminum or an aluminum alloy containing aluminum as a main component and a trace amount of foreign atoms. These foreign atoms include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign atoms is at most 10% or less. Aluminum suitable for the present invention is pure aluminum, or since completely pure aluminum is difficult to produce due to smelting technology, it is preferable to use aluminum with as low a content of foreign atoms as possible. Furthermore, any aluminum alloy having the above-mentioned content can be said to be a material that can be applied to the present invention.

As described above, the composition of the aluminum plate applied to the present invention is not specified; conventionally known and publicly used materials can be used as appropriate. The thickness of the aluminum plate used in the present invention is approximately 0.1 ff1m ~
It is approximately 0.5 mm.

Prior to anodizing the aluminum plate, degreasing treatment, such as treatment with a surfactant or alkaline aqueous solution, and graining treatment are carried out, if desired, to remove rolling oil from the surface.

Graining treatment methods include a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. As a method for mechanically roughening the surface, known methods such as ball polishing, brush polishing, blast polishing, puff polishing, etc. can be used.

Further, as an electrochemical surface roughening method, there is a method in which alternating current or direct current is used in a hydrochloric acid or nitric acid electrolyte. Also,
It is also possible to use a method that combines both methods, as disclosed in Japanese Patent Application Laid-Open No. 54-63902.

The aluminum plate thus roughened is subjected to alkali etching treatment and neutralization treatment as necessary.

The surface thus treated is provided with a hydrated oxide film. A hydrated oxide film is formed by immersing an aluminum plate in hot water. The preferred temperature is 50°C~
It is selected appropriately at +00°C.

In addition, in order to form a hydrated oxide film on the surface in a short period of time, it is necessary to add
It is preferable to immerse at 100°C.

Preferred alkaline agents include hydroxides of alkaline earth elements and alkali metals, amines such as aqueous ammonia, triethanolamine, monoethanolamine, and jetanolamine, and carbonates such as soda carbonate and potassium carbonate. The processing time may be appropriately selected from the range of 10 seconds to 300 seconds.

The surface thus treated is subsequently anodized.

A preferred electrolyte is sulfuric acid. Phosphoric acid, oxalic acid, chromic acid, etc. are also known electrolytes, and are not suitable for industrial production because they have problems such as pollution and high voltage.

The processing conditions for anodic oxidation are generally such that the electrolyte concentration is 1 to 1.
80% by weight solution, liquid temperature 5-70℃, current density 5-60
A/dm2, voltage 1~100V1 electrolysis time 10 seconds~50
It is appropriate if it is within the range of minutes.

The amount of anodized film is preferably in the range of 0.1 to I Og/rrr, more preferably in the range of 1 to 6 glrd. A positive photosensitive diazo compound layer containing Oginonediazide is provided on the surface provided with the anodic oxide film in this manner.

Particularly preferred O-quinonediaside compounds are O-naf).
Quinonediaside compounds, such as those described in U.S. Patent No. 2.7
66, No. 118, No. 2.767, 092, No. 2,
No. 772.972, No. 2.859.112, No. 2
．． 907.665, 3.046.110, 3.046.111, 3046115, 3
．． 046.118, 3.046.119, 3.046.1.20, 3.046. +2] No. 3, No. 046.122, No. 3.046.123
No. 3.061,430, No. 3.1.02.8
No. 09, No. 3.106.465, No. 3, 635.
No. 709 and No. 3.647.443, and are described in numerous publications, which can be suitably used. Among these, in particular, 0-naphthoquinonediazide sulfonic acid ester or ○-naph I quinonediazidecarboxylic acid ester of aromatic hydroxyl compounds, and O-naphthoquinonediazide sulfonic acid amide or 0-naphthoquinone cyasitocarboxylic acid of aromatic amino compounds. Amides are preferred, especially U.S. Pat.
35.709, a condensate of pyrogallol and acetone subjected to an ester reaction with 0-naphthoquinonediazide sulfonic acid, U.S. Patent No. 4.0281
British Patent No. 1.494.043, which is obtained by subjecting O-naphthoquinonediazide sulfonic acid or O-naphthoquinone cyasitocarboxylic acid to an ester reaction with a polyester having a hydroxyl group at the end as described in Specification No. 11. A homopolymer of p-hydroxystyrene or a copolymer of this with other copolymerizable monomers as described in
- an ester reaction product of naphthoquinonediazidecarboxylic acid, U.S. Pat. No. 3,759.7]. Those obtained by subjecting 0-naphthoquinone diazide sulfonic acid or 0-naphthoquinone cyasitocarboxylic acid to an amide reaction are very excellent.

These O-quinonediazide compounds can be used alone, but it is preferable to use them in combination with an alkali-soluble resin. Suitable alkali-soluble resins include novolac type phenolic resins, and specifically include phenol formaldehyde resins, O-cresol formaldehyde resins, m-cresol formaldehyde resins, and the like. Furthermore, as described in U.S. Pat. No. 4,123,279, along with the above-mentioned phenolic resins,
It is even more preferable to use a phenol substituted with an alkyl group having 3 to 8 carbon atoms, such as t-butylphenolpolmaldehyde resin, or a condensate of cresol and formaldehyde. The alkali-soluble resin has a content of about 50 to about 85% based on the total weight of the composition constituting the photosensitive layer.
% by weight, more preferably 60-80% by weight.

The photosensitive composition containing the 0-quinonediaside compound may optionally further contain dyes, plasticizers, such as British Patent No.],
Additives can be added, such as components that provide printout performance, such as those described in U.S. Pat. No. 401.463, U.S. Pat.

Dyes include basic dyes and oil-soluble dyes. Specifically, Victoria Pure Blue BOH, Victoria Blue BR, Methyl Violet, Eisen Malachite Green (manufactured by Hodogaya Chemical Industry), Patent Pure Blue VX10-Damine B1.
Basic dyes such as methylene blue (manufactured by Sumima Kagaku Kogyo), Sudan Blue ■, Victoria Blue F4R (manufactured by B, A, S, P), oil-
・Blue・#603, Oil-・Blue・BO3, Oil-・Blue・IIN (manufactured by Orient Chemical Industry)
Oil-soluble dyes such as

Among these dyes, basic dyes are preferred, and most preferably those whose counter anion has one sulfonic acid group, such as naphthalene sulfonic acid, as the only exchange group.

As a photodegradable acid generator, 1,2-naphthoquinone-(2
)-4-Sulfonic acid chloride, O trihalomethyl-2-pyrone and trihalomethyltriazine described in JP-A-53-36223, JP-A-55
Various O naphthoquinonediaside compounds described in Japanese Patent Application Laid-Open No. 55-77742,
-Trihalomethyl5-aryl-1,3,4-oxadiazole compounds and the like can be added.

Further details of photosensitive layers containing O-quinone diazi) compounds and their developers are described in detail in U.S. Pat. No. 4,259,434.

The photosensitive layer described above is coated onto the support to a thickness of 1 to 3 g/in (weight after drying).

EXAMPLES In order to explain the present invention in more detail, Examples are shown below.

EXAMPLE The surface of a JI31050 aluminum sheet was grained using a rotating nylon brush using a vamisu water suspension as an abrasive. The surface roughness at this time (center line average roughness) is 0.5
It was μ. After washing with water, add 10% caustic soda solution at 70°C.
It was immersed in a solution warmed to C and etched so that the amount of aluminum dissolved was 6 g/rd. After washing with water, 30
% nitric acid aqueous solution for 1 minute to neutralize it, and thoroughly washed with water.

After that, in a 0.7% nitric acid aqueous solution, using a square wave alternating waveform with an anode voltage of 13 volts and a cathode voltage of 6 volts (
Power supply waveform described in the example of JP-A-52-77702) Electrolytic coarsening was performed for 20 seconds, and 20% sulfuric acid
After cleaning the surface by immersing it in a 0°C solution, it was washed with water.

This surface was treated as follows.

■ Ion-exchanged water was boiled and immersed in the solution for 5 minutes. (Substrate ■) ■ A solution adjusted to pH 9 using K OH at 100°
C. and immersed in water for 1 minute. (Substrate ■) At the same time,
I also prepared a substrate ■ that does not undergo any processing, and these substrates ■, ■,
175 g/I on the surface of ■! in a sulfuric acid solution (7.5 g
2.2 g/m and 3 g/rd of Ig/m, respectively, were applied at 30°C.

A photosensitive layer was provided on the substrate thus prepared by applying the following composition to a coating weight after drying of 2.5 g/g.

Photosensitive composition Cresol novolac resin 2.00g Ethylene dichloride 16 [? 12 g of 2-methoxyedyl acetate The photosensitive lithographic printing plate thus prepared was exposed in a vacuum printing frame through a transparent positive film for 50 seconds using a 3 kW metal halide lamp from a distance of 1 m. SiO□
/Na2O molar ratio 5. of sodium silicate with a molar ratio of 1.74.
It was developed with a 26% aqueous solution (1) H=12.7).

After developing in this manner, the coloration of the non-image area was measured using ultraviolet spectroscopic absorption method. (The difference with the uncolored support was expressed as the difference in optical density at 600 nm.) Printing was also carried out using this printing plate. Table 1 shows the number of printed sheets.

The results in Table 1 demonstrate the excellent effects of the method of the present invention.

Table 1 [Effects of the Invention] The positive photosensitive lithographic printing plate of the present invention has excellent adhesion between the image area and the support, and is less likely to cause coloring in the non-image area.

Claims (1)

[Claims] A positive photosensitive lithographic printing plate comprising a support obtained by forming a hydrated oxide film on a grained aluminum surface and then anodizing it in a sulfuric acid electrolyte, and providing a photosensitive layer containing o-quinonediazide on the support. .