JPH01118489A - Method of manufacturing aluminum support for print - Google Patents

Abstract

PURPOSE:To form a uniform sand pattern by a method wherein a support is subjected to an electro-roughing treatment in a solution mainly incorporating hydrochloric acid, and wherein the support is then subjected to another electro-roughing treatment in a solution mainly incorporating nitric acid after the same has been subjected to a smut removing treatment for removing smuts produced due to the hydrochloric acid treatment or to an etching treatment. CONSTITUTION:An electro-roughing treatment is conducted in a solution mainly incorporating hydrochloric acid by utilizing an alternating current waveform. Afterwards, a smut removing treatment is conducted for removing smuts produced during the electro-roughing treatment, and an etching treatment is also conducted for etching the edge of a pit. Another electro- roughing treatment is conducted in a solution mainly incorporating nitric acid. The electrolyte to be used for the first electro-roughing treatment is a solution incorporating hydrochloric acid in an amount ranging from 1-30g/l, and the current density and liquid temperature preferably ranges from 1 to 200A/dm and from 20 to 50 deg.C, respectively, and the electro- roughing treatment time preferably ranges from 5 to 90sec. The electrolyte to be used for the second electro-roughing treatment is a solution mainly incorporating nitric acid in an amount ranging from 5 to 400g/l, and the current density and liquid temperature preferably ranges from 1 to 200A/dm and from 30 to 80 deg.C, respectively, and the electro-roughing treatment time preferably ranges from 5 to 90sec.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a support for a printing plate, and in particular a printing plate made of a roughened aluminum plate suitable for offset printing plates. The present invention relates to a method for manufacturing a support for

[Conventional technology]

Aluminum plates (including aluminum alloy plates) are used as printing plate supports, particularly offset printing plate supports.

Generally, in order to use an aluminum plate as a plate material (support) for offset printing, it is necessary to have appropriate adhesion to a photosensitive material and water retention.

For this purpose, the surface of the aluminum plate must be roughened to have uniform and dense grains. This surface roughening treatment has a significant effect on the printing performance and stiffness resistance of the plate material when offset printing is actually performed after plate making, so its quality is an important factor in the manufacture of the plate material.

The alternating current electrolytic etching method is generally used to roughen the surface of aluminum supports for printing plates, and the current used is a special alternating waveform current such as an ordinary sine wave alternating current or a square wave. . The surface of the aluminum plate is then roughened using an alternating current using a suitable electrode such as graphite as a counter electrode, and is usually carried out in one cycle.

The electrolytic bath used for the electrolytic surface roughening treatment includes hydrogen chloride or an aqueous solution mainly composed of hydrogen chloride (hereinafter referred to as a hydrochloric acid bath), and nitric acid or an aqueous solution mainly composed of hydrogen chloride (hereinafter referred to as a nitric acid bath).
It is common to use

When electrolytic surface roughening treatment is performed using a hydrochloric acid bath, deep and large pits are likely to be formed, but when electrolytic surface roughening treatment is performed using a nitric acid bath, relatively shallow small pits are likely to be formed.

Using an electrolytic surface roughening method, an aluminum plate suitable as a support for a printing plate having a grain in which pits deep relative to its diameter are uniformly and densely present is obtained.
A number of methods have been proposed.

The methods include the ratio of the amount of electricity at the anode and cathode during electrolytic surface roughening using alternating current (Japanese Patent Laid-Open No. 54-65607), the power supply waveform (Japanese Patent Laid-Open No. 55-25381), and the unit. Combination of energization amount per area (Unexamined Japanese Patent Publication No. 56-29
No. 699) and the like are known.

[Problem that the invention seeks to solve]

However, even with this method of manufacturing an aluminum support for printing plates, the pits generated are not deep enough and lack uniformity, so when an offset printing plate is formed, printing performance and printing durability are affected. It's not enough and you can't get what you're satisfied with.

An object of the present invention is to provide a method for manufacturing an aluminum support for a printing plate in which the pits formed are deep, have large undulations, and have uniform grains, solving the conventional problems. be.

[Means and effects for solving the problem] As a result of various studies, the present inventors have found that after performing electrolytic surface roughening treatment using an alternating current waveform in an aqueous solution containing mainly hydrochloric acid, the electrolytically roughened surface By removing the smut generated in the chemical treatment or etching the pinto edges, and then electrolytically roughening the surface in an aqueous solution containing mainly nitric acid, the surface is deep compared to its diameter. Industrially, rough-surfaced aluminum plates with large undulations and a double-layered grain structure of overlapping honeycomb-like round uniform grains are suitable as aluminum supports for printing plates with excellent printing performance. It has been found that it can be manufactured advantageously.

That is, the above object of the present invention is to perform an electrolytic surface roughening treatment on an aluminum support in an aqueous solution mainly containing hydrochloric acid, and to remove smut generated by the electrolytic surface roughening treatment or etching including a smut removal treatment in the middle. This is achieved by a method for producing an aluminum support for a printing plate, which is characterized by carrying out a treatment, and then carrying out an electrolytic surface roughening treatment with an aqueous solution containing mainly nitric acid.

In the present invention, electrolytic surface roughening treatment is carried out in an aqueous solution mainly containing hydrochloric acid in the first stage, which means that the aluminum plate and the aluminum plate are subjected to an electrolytic surface roughening treatment in an aqueous solution mainly containing hydrochloric acid, although a mixed solution with other acids may be used. By passing an alternating current between the opposing electrodes and performing electrolytic surface roughening treatment, the electrolytic solution at that time is an aqueous solution containing 1 to 30 g/β of hydrochloric acid, and the current density is 1 to 200 A/dnf. It is desirable that the temperature is in the range of 20 to 50°C. Electrolytic surface roughening treatment time is 5 to 9
Preferably, it is in the range of 0 seconds.

In the present invention, the process of removing smut generated by the electrolytic surface roughening treatment in the middle is intended to remove the smut components generated by the electrolytic surface roughening treatment in the hydrochloric acid bath in the previous stage, and , immersion in hot nitric acid solutions, chromium-phosphate solutions, high-pressure water jetting, electropolishing in phosphoric acid or sulfuric acid electrolytes, immersion in caustic soda, or etching including smut removal treatments. Any processing method can be used. In this intermediate smut removal process, it is not necessary that the smut removal is complete.

However, it is necessary to take care before and after the electrolytic surface roughening treatment so that the smut removal solution or etching solution after the electrolytic surface roughening treatment does not mix with the electrolytic surface roughening treatment solution.

In the present invention, electrolytic surface roughening treatment is carried out in an aqueous solution mainly containing nitric acid in the second stage, which means that a mixed solution with other acids may be used. Electrolytic surface roughening is carried out by passing an alternating current between the electrode and the electrode facing the electrode, and the electrolyte is an aqueous solution containing 5 to 400 g/A of nitric acid, and the current density is 1 to 20 OA. /d port, liquid temperature 30-8
It is desirable that the temperature is in the range of 0℃, and the electrolytic treatment time is 5~
Preferably, the time is in the range of 90 seconds.

In this way, it is possible to generate a double-bit structure of grain on the surface of the aluminum plate, which has fine, round, and uniform honeycomb-like pits on the pit surface of the deep grain.

The aluminum plate subjected to electrolytic surface roughening treatment in this way is
If necessary, according to commonly used methods, room temperature to 90°C
After mild etching in an aqueous solution containing an acid or alkali, neutralization treatment or the like may be performed. For light etching, not only immersion but also electrochemical methods such as electrolytic polishing may be used. By performing a mild etching treatment, an even better support for a printing plate can be obtained.

Furthermore, degreasing and cleaning treatment with acid or alkali as a pretreatment for electrolytic surface roughening, which is carried out as a conventional method, may or may not be carried out.

The alternating current waveform used in the present invention is a current waveform obtained by alternating positive and negative polarities, and an example of the voltage waveform diagram is shown in FIG. In Figure 2, (al
is a sine wave, (1)) is a sine wave whose phase angle is controlled by a thyristor, and TC) is a rectangular wave voltage waveform, but the alternating current waveform of the present invention is not limited to the voltage waveforms described above.

Furthermore, in the present invention, the electrolytic solution used in the electrolytic surface roughening treatment is not limited to only hydrochloric acid and nitric acid, but if the electrolytic solution is mainly hydrochloric acid, or nitric acid, it can be hydrochloric acid and sulfuric acid, hydrochloric acid and nitric acid, or nitric acid. A mixture of sulfuric acid may also be used. In this case, phosphoric acid or a mixture of phosphoric acid and sulfuric acid or other acids may be used instead of sulfuric acid.

The roughened plate obtained as described above is anodized in an electrolytic solution containing sulfuric acid or phosphoric acid according to a conventional method, thereby providing a printing plate support with excellent hydrophilicity, water retention, and rigidity. You can manufacture your body. Of course, after the anodic oxidation treatment, it may be immersed in an aqueous solution containing sodium silicate or the like to perform a hydrophilic treatment.

The electrolysis method according to the present invention can be applied to any of the batch method, semi-continuous method, and continuous method.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example-1 A JISlloo-, H16 aluminum rolled plate was immersed in a 5% caustic soda aqueous solution at 50° C. for 30 seconds to perform a cleaning treatment.

This aluminum plate was soaked in hydrochloric acid 15 g/I1. Electrolytic etching was performed for 20 seconds at a current density of 60 A/dn (25"C1) in an aqueous solution containing
% caustic soda aqueous solution at 35° C. for 10 seconds to remove smut components generated by electrolytic surface roughening treatment, and then washed with water.

Next, nitric acid 15g/j! Electrolytic etching was performed for 5 seconds at 40° C. and a current density of 4 OA/dm in an aqueous solution containing . The smut consisting mainly of aluminum hydroxide adhering to the surface of the aluminum plate thus obtained was soaked in an aqueous solution of 250 g/j of sulfuric acid and a liquid temperature of 60'C.
It was immersed for 0 seconds, removed, and washed with water.

The roughened plate thus obtained has an average surface roughness of 0.7μ
m, it had a uniform and dense double structure of unevenness, with small round honeycomb-like foci on top of the large undulations. Further, 100 g/n of sulfuric acid was added to the aluminum plate obtained as above so that the amount of oxide film was 3 g/n (
Anodization treatment was performed in an aqueous solution containing β.

A photosensitive layer was coated on the aluminum plate thus obtained to produce a printing plate, and the obtained printing plate had good plate-making properties, printing durability, and staining.

Example 2 A printing plate was produced by carrying out a surface roughening treatment in exactly the same manner as in Example 1, except that washing with caustic soda was not performed as a pretreatment for electrolytic surface roughening. The obtained aluminum plate had a grain structure similar to that of Example-1, and no non-uniformity in the grain was observed due to the omission of the pretreatment step using caustic soda.

Example-3 JISIloo-H16 aluminum rolled plate was soaked in hydrochloric acid 15
In an aqueous solution containing g/β, 25°C9 current density 60A/
Electrolytic etching was performed for 20 seconds using DNR. At that time, a rectangular wave as shown in FIG. 1 was used as the power supply waveform.

Water Washing The sample was immersed in an aqueous solution containing 400 g/# of condensed sulfuric acid at 60° C. for 10 seconds to remove the smut component generated in the electrolytic surface roughening treatment, and then washed with water.

Next, electrolytic etching was performed for 5 seconds at 40 DEG C. and a current density of 40 A/d% in an aqueous solution containing 15 g/A of nitric acid. The smut consisting mainly of aluminum hydroxide adhering to the surface of the aluminum plate obtained in this way,
Sulfuric acid 250 g/7! It was removed by immersing it in an aqueous solution at a temperature of 60° C. for 30 seconds, and then washed with water.

The roughened plate thus obtained has an average surface roughness of 0.7μ
m, it had a uniform and dense double structure of unevenness, with small round honeycomb-like foci on top of the large undulations. Further, 100 gzJ of sulfuric acid was added to the aluminum plate obtained as above so that the amount of oxide film was 3 g/m.
! Anodization treatment was performed in an aqueous solution containing

A photosensitive layer was coated on the aluminum plate thus obtained to produce a printing plate, and the obtained printing plate had good plate-making properties, printing durability, and staining.

[Effects of the Invention] In the present invention, an aluminum support is subjected to an electrolytic surface roughening treatment in an aqueous solution containing mainly hydrochloric acid, an intermediate treatment is performed to remove smut generated by the electrolytic surface roughening treatment, or an etching treatment is performed, and then A method for producing an aluminum support for printing plates, which is characterized by performing electrolytic surface roughening treatment in an aqueous solution containing mainly nitric acid, produces smut produced by electrolytic surface roughening treatment in a hydrochloric acid bath in the first step. eliminate the influence of
It is possible to generate fine, round, and uniform honeycomb-shaped pits that correspond to the conditions of the subsequent electrolytic treatment on top of the large undulating grains generated by the electrolytic roughening treatment in the first stage, and the electrolytic roughening of both By combining surface forming conditions, it is possible to easily obtain a double-focus structure grain having any depth and having characteristics of the grain of both hydrochloric acid bath and nitric acid bath.

By producing an offset printing plate from a rough aluminum plate produced by the method of the present invention, it is possible to produce an offset printing plate with excellent printing performance and high printing durability.

[Brief explanation of the drawing]

1 and 2 are voltage waveform diagrams of alternating current waveforms according to the present invention. Figure 1 (a) (b) (C)

Claims (1)

[Claims] (1) Perform electrolytic surface roughening treatment on the aluminum support in an aqueous solution containing mainly hydrochloric acid, perform an intermediate treatment to remove the smut generated by the electrolytic surface roughening treatment, and then electrolyze it in an aqueous solution mainly containing nitric acid. A method for producing an aluminum support for printing plates, which comprises performing surface roughening treatment.