JPH01237197A - Production of planographic support - Google Patents

Abstract

PURPOSE:To perform uniform graining and obtain a planographic support having excellent printing performance, by subjecting an aluminum support to an alkali etching treatment in an extremely limited degree within a specified range, and then to an electrolytic graining treatment in an acidic electrolytic liquid. CONSTITUTION:An aluminum support is subjected to an alkali etching treatment in an extremely limited degree within the range of 0.01-1.0g/m<2>, and then to an electrolytic graining treatment in an acidic electrolytic liquid. This method is particularly effective when the aluminum support contains 0.3-3% of manganese, and the electrolytic liquid is preferably an aqueous solution comprising nitric acid as a main constituent. In the alkali etching treatment, a preferable alkali agent to be used is sodium hydroxide, potassium hydroxide, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate or the like, the concentration of which is 0.001-5%, the etching temperature is 20-90 deg.C, and the etching time is 1sec - 5min. Subsequently, the surface of the aluminum plate is electrolytically grained in the acidic electrolytic liquid. The electrolytic liquid is preferably a 0.1-10wt.% nitric acid solution, and AC electrolytic etching is carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a support for a printing plate, and in particular to a method for manufacturing a support for a printing plate, and in particular, a support made of a roughened manganese-containing aluminum plate that is used in planographic printing plates. The present invention relates to a method for producing a support for a printing plate.

[Conventional technology]

As a support for printing plates, especially as a support for lithographic printing plates, 1 sheet aluminum is used, and due to the diversification of users, aluminum plates have changed from pure aluminum with very few impurities to pure aluminum by adding manganese. It is becoming more diverse, including those that increase strength. In particular, materials with manganese added have increased strength, and the amount of specifications will tend to increase in the future.

In addition, in order to use an aluminum plate as a support for a lithographic printing plate, it is necessary to have appropriate adhesion to the photosensitive material and water retention.

To achieve this, the surface of the aluminum plate must be roughened so that it has a uniform and dense grain.This roughening process affects the staining performance of the plate material during actual printing after plate making. Since it has a significant effect on printing durability, etc., its quality is an important factor in the production of plate materials.

As a method for roughening aluminum supports for printing plates, alternating current electrolytic surface roughening method is generally adopted.As for the current, special alternating current such as ordinary sine wave alternating current/R current or rectangular wave is used. It is used. In addition, as a pretreatment for this alternating current electrolytic surface roughening, it was common to remove the surface layer by etching with caustic soda (for example,
Publication No. 918).

[Problem that the invention seeks to solve]

However, with conventional etching treatment, uniform surface roughening cannot be obtained in the subsequent alternating current electrolytic roughening, and this tendency is particularly noticeable when aluminum materials contain manganese etc. due to the diversification of aluminum materials as mentioned above. Therefore, it was necessary to consider alkali etching as a pretreatment.

That is, conventional alkaline etching generally requires 3 g
/ m or more is required, but if such etching is performed, the surface of the aluminum plate will not be etched uniformly, and especially if it contains 0.3% or more of manganese, etc., the bond between aluminum and manganese, etc. will increase. It has been found that it is more difficult to obtain uniform etching due to the influence of intermetallic compounds, and as a result, the surface cannot be uniformly roughened by AC electrolytic roughening, which adversely affects the quality of the printed image.

An object of the present invention is to provide a method for producing a support for a lithographic printing plate that can uniformly roughen an aluminum plate by roughening the surface by alternating current electrolysis and has excellent printing performance.

[Means and effects for solving the problem] As a result of the study of the etching amount, the present inventors determined that the etching amount was 0.01 g/n (~1 g
It has been discovered that the object can be achieved by performing alkali etching with a small loss in the range of /rd, and the present invention has been achieved.

However, the above object of the present invention is to provide an aluminum support with a thickness of 0.
This is achieved by performing an alkaline etching treatment with a small loss in the range of 0.018/m to 1.0 g/m, followed by electrolytic surface roughening treatment in an acidic electrolyte.

In the present invention, the aluminum support contains 0.3% or more3.
% or less of manganese, and an aqueous solution containing nitric acid as a main component is preferable as the acidic electrolyte for electrolytic surface roughening treatment.

As for the conditions for the alkali etching treatment with minimal loss in the present invention, preferred alkaline agents include caustic soda, caustic potash, sodium silicate, soda carbonate, sodium aluminate, and sodium gluconate. That one time was o, oo
t%~5%, temperature 20℃~90℃, time 1 second~5%
Selected from a range of minutes.

Since alkali-insoluble substances (smut) remain on the surface of such an alkali-etched aluminum plate, a desmutting treatment may be performed as necessary.

Subsequently, the surface of the aluminum plate was soaked in an acidic electrolyte.
The surface is electrolytically roughened. The electrolytic solution at this time is preferably hydrochloric acid, nitric acid, or a mixture thereof, and nitric acid is more preferred. The content of nitric acid is 0.1 to 10% by weight, more preferably 0.1% by weight.
AC electrolytic etching is carried out in a 3-3% by weight solution. The current waveform is appropriately selected depending on the desired grain shape.

The roughness of the surface varies depending on the amount of electricity used for electrolysis. The bit depth of the primary assembly surface is 0.1 to 10 μm, and the third bit diameter is more preferably 0.2 to 20 μm, preferably a focus depth of 2 to 4 μm, and a pit diameter of 5 to 15 μm. In order to form such a pit diameter, it is more preferable to use the special alternating waveforms described in Japanese Patent Publication No. 56-19280 and Japanese Patent Publication No. 55-19191.

S. In the present invention, a support for a lithographic printing plate can be obtained by forming a primary surface that is good for maintaining appropriate adhesion with the photosensitive agent and water retention, but the following treatment is also performed. It is preferable.

It is preferable that the aluminum on which the primary assembled surface is formed is subsequently treated with an acid or alkaline solution.

Specifically, in addition to the sulfuric acid described in Japanese Patent Publication No. 56-11316, phosphoric acid or a mixture of phosphoric acid and chromic acid is used. Further, smut adhering to the surface is removed by lightly desmutting with an alkaline solution such as caustic soda as described in Japanese Patent Publication No. 48-28123. When removing adhered smut with an alkaline solution, it is preferable to desmut again with an acidic solution (sulfuric acid, phosphoric acid, chromic acid, etc.) since components insoluble in alkali may remain.

After this, if necessary, the secondary composite surface may be overlapped using the same method as the primary phase surface generation method.The focus depth of the secondary composite surface is 0.
．． More preferably, the pit depth is 0.1 to 0.8 μm and the focus diameter is 0.1 to 3 μm.

Preferably, the aluminum with the secondary assembled surface is subsequently treated with an acid or alkaline solution. Specifically, in addition to the sulfuric acid described in Japanese Patent Publication No. 56-11316, phosphoric acid or a mixture of phosphoric acid and chromic acid is used. Further, smut adhering to the surface is removed by lightly desmutting with an alkaline solution such as caustic soda as described in Japanese Patent Publication No. 48-28123. When removing adhered smut with an alkaline solution, it is preferable to desmut again with an acidic solution (sulfuric acid, phosphoric acid, chromic acid, etc.) because alkali-insoluble components may remain as described above.

After that, anodic oxidation is performed as the final treatment, and the anodic oxide film has a concentration of 0.1 to Log/n (more preferably 0
．． It is best to form it on the surface at a rate of 3-5 g/m.

It is preferable to perform alkali etching and desmutting treatment before applying the anodic oxide film.

The conditions for anodic oxidation vary depending on the electrolyte used, so they cannot be determined unconditionally, but generally, the concentration of the electrolyte is 1 to 80% by weight, the temperature is 5 to 70°C, and the current density is 0. 5~60 A/d g, voltage 1~100■,
An appropriate electrolysis time range is from 10 seconds to 5 minutes.

The grained aluminum plate with the anodic oxide film obtained in this way is itself stable and has excellent hydrophilic properties, so a photosensitive coating can be immediately applied on top, but if necessary, the surface can be further coated. Can be processed. For example, a silicate layer made of an alkali metal silicate or an undercoat layer made of a hydrophilic polymer compound can be provided. The coating amount of the undercoat layer is preferably 5 to 150 μ/d.

A photosensitive lithographic printing plate is obtained by providing a photosensitive coating on the aluminum support thus treated. To use this for printing, after image exposure, development, and plate making, it is set in a printing machine and printing begins.

〔Example〕

Example-1 A 1% aqueous solution of caustic soda was heated to 30°C on an aluminum support made of JIS3003 material (Mg 1.1%). It was immersed in liquid No. 8 and etched so that the amount of aluminum dissolved was 0.1 g/rd. After washing with water, it was immersed in a 3% nitric acid aqueous solution and thoroughly washed with water.

After washing with water, in a 1.5% nitric acid aqueous solution,
The surface was electrochemically roughened using the alternating waveform current described in Publication No. 1.

The electrolytic conditions were set to V a - 12.7 volts, V = 9.1 port, and the amount of electricity during positive operation was 600 clones/dn. After removing the smut on the surface, it was observed with an electron microscope photo. As a result, a large focus of about 10 μm and a narrow pit of about 1 μm were uniformly generated.
% sulfuric acid, an anodized film of 2.5 g/m was applied, washed with water, and dried.

This will be referred to as a substrate (A).

Comparative Example-1 J [10% caustic soda aqueous solution was heated to 60°C on an aluminum support made of 53003 material? 8 Immersed in liquid,
Etching was performed so that the amount of aluminum dissolved was 5 g/rd. After washing with water, it was immersed in a 10% nitric acid aqueous solution and thoroughly washed with water.

After washing with water, the surface was roughened in the same manner as in Example 1, and the smut on the surface was removed and observed with an electron microscope. As a result, 30μ
There were large pits, the shape of the grain was uneven, and there were many end-etched areas (manganese precipitated areas). This support is 2
Anodic oxide film 2.5g/n in 0% sulfuric acid? It was set up, washed with water, and dried.

Let this kitei resistance be CB).

A photosensitive layer was provided by applying the following composition to the substrates [A] and [B] prepared as above so that the coating weight after drying was 2.0 g/durability.

Sensitivity 7 nights N-(4-hydroxyphenyl)methacrylamide/2
-Hydroxyethyl methacrylate/acrylonitrile/methyl methacrylate/methacrylic acid (= 15:
10:30:38:7 molar ratio) copolymer (average molecule 1160000)...5.0
g4-Hexafluorophosphate of the condensate of diazodiphenylamine and formaldehyde 0.5 g Solanous acid 0.05 g Dictoria Pure Blue BOH (Odugaya (manufactured by Chemistry)
・・・・・・・・・0.1 g2-Methoxyethanol・・・・・・100 g After exposure for 50 seconds with a metal halide lamp of 3 - from a distance of 1 m,
A lithographic printing plate was prepared by developing with a developer having the following composition and gumming with an aqueous gum arabic solution.

Developer Sodium sulfite: 5g Hensyl alcohol: 30g Sodium carbonate
・・・・・・・・・5g Sodium isopropylnaphthalene sulfonate
・・・ ・・・ 12g pure water
...1000 g Using the printing plate made in this way, printing was carried out according to the usual procedure, and the results are shown in Table 1.

Table 1 Example-2 A support made of JISI100 material (99% At or higher) that is close to pure aluminum was electrochemically roughened using the same treatment method as in Example 1, and the surface smut was removed and the support was photographed using an electron microscope. Observed. As a result, large pits of about 15 μm and thin pits of about 1 μm were uniformly generated. This support
An anodized film of 2.5 g/i was applied in 20% sulfuric acid, washed with water, and dried.

This will be referred to as a substrate (CD).

Comparative Example 2 An aluminum support made of JISI 100 material was electrochemically roughened using the same treatment method as in Comparative Example 2, and the smut on the surface was removed and observed using an electron microscope. As a result, there were large pits of about 25 μm, and the shape of the grains was non-uniform. This support was coated with an anodized film of 2.5 g/= in 20% sulfuric acid, washed with water, and dried. This substrate is referred to as 1D].

The substrates (C) and CD produced as described above are
), a composition similar to (B) was applied, dried to form a photosensitive layer, developed, and printed.

〔Effect of the invention〕

As mentioned above, in accordance with the present invention, an aluminum support of 0.
After a very small amount of alkali etching in the range of 0.01 g/M to 1.0 g/n, electrolytic surface roughening treatment is performed in an acidic electrolyte, resulting in uniform grains and a planographic plate with excellent printing performance. A printing plate support was obtained.

Procedural amendment September 22, 1986

Claims (4)

[Claims] (1) Aluminum support at 0.01g/m^2~1
．． A method for producing a lithographic printing plate support, which comprises performing an extremely small alkaline etching treatment in the range of 0 g/m^2, followed by an electrolytic surface roughening treatment in an acidic electrolyte. (2) 0.3% manganese in the aluminum support
% or more of the lithographic printing plate support according to claim 1. (3) The conditions for the minimally alkaline etching treatment are an alkali agent concentration of 0.001 to 5% and a temperature of 20 to 9%.
3. The method for producing a lithographic printing plate support according to claim 1 or 2, characterized in that the temperature is 0° C. and the time is 1 to 5 minutes. (4) Claim 1, characterized in that the acidic electrolytic solution for electrolytic surface roughening treatment is an aqueous solution mainly containing nitric acid.
, 2, or 3. The method for producing a lithographic printing plate support according to item 3.