JPH0818469B2 - Method for producing lithographic printing plate support - Google Patents

Description

TECHNICAL FIELD The present invention relates to a roughening method for a printing plate support, and more particularly to a roughening method for a printing plate support made of an aluminum plate containing manganese. It is about.

[Conventional technology]

An aluminum plate is used as a printing plate support, particularly a lithographic printing plate support, and manganese is added to the aluminum support from a material close to pure aluminum containing a very small amount of iron and silicon due to diversification of users. There are a wide variety of support materials. Further, the tensile strength of the support to which manganese is added is greatly increased as compared with that of pure aluminum, and the tendency is to increase further in the future.

As a roughening method of the aluminum support for printing plates,
There are mechanical graining methods, electrochemical graining methods, etc., and the roughening is performed by combining them in a timely manner.

Mechanical graining methods include, for example, ball graining, wire graining, brushing rain, and liquid honing. As the electrochemical graining method, the alternating current electrolytic etching method is generally adopted,
As the current, a special alternating current such as an ordinary sine wave alternating current or a rectangular wave is used. Further, as a pretreatment for this electrochemical graining, etching treatment with caustic soda may be performed.

The thus roughened aluminum support is anodized to obtain a lithographic printing plate support (for example, Japanese Patent Publication No. 57-16918).

In recent years, the number of aluminum supports containing manganese has increased, but since manganese, copper, iron, etc. are contained in the aluminum supports, the pits formed by electrochemical graining are affected by such impurities. The pit diameter was large, and the pit diameter was large and the deep grain had good printing durability, but it was a lithographic printing plate support with poor photosensitive performance because the photosensitive layer was likely to remain after development.

Regarding the electrochemical graining method, various studies have been made in recent years, for example, in U.S. Pat.No. 4,482,434,
It is disclosed that uniform pits are generated when the surface is roughened with an electrolytic solution at an alternating current of 1.5 to 10 Hz. However, at 10 Hz or less, there was a problem that only a large pit diameter could be produced and only a printing plate with poor stain performance could be produced. In addition, U.S. Pat. Nos. 4,297,184, 4,279,714, and 4,279,715.
Each specification indicates that the solution is mainly hydrochloric acid, and the frequency is about 20 Hz, but since the bath is mainly hydrochloric acid,
It was difficult to get a grain with a small pit diameter. Also,
In U.S. Pat.No. 4,548,683, the alternating current is 140 to 400 Hz,
It is shown that roughening in an acidic electrolyte at a current density of 7 to 22 A / dm ² produces uniform pits without producing smut, but when the frequency is as high as 140 Hz or higher. ,
When impurities such as copper, manganese, and iron increase, there is a problem that uniform pits are not formed.

[Problems to be solved by the invention]

However, in recent years, it has been desired to provide a printing plate support having a good stain performance, and it is desired to produce a grain having a uniform and small pit diameter even if it contains impurities other than aluminum by a method capable of mass production. It was rare.

An object of the present invention is to provide a lithographic printing plate suitable for mass-producing a printing plate support having a small pit diameter even if it contains impurities other than aluminum according to the above demand, and can evenly generate a small pit diameter. It is to provide a method for producing a plate support.

[Means and Actions for Solving Problems]

In the electrochemical graining method, the present inventors have
As a result of earnest research on frequency, bath composition, temperature and the like, the present invention has been achieved.

That is, the above-mentioned object of the present invention is a planographic printing plate characterized by roughening an aluminum support using an alternating current having a frequency in the range of 10 to 20 Hz in an electrolytic solution containing nitric acid as a main component. This is accomplished by the method of manufacturing the support.

The present invention is effective for an aluminum plate, particularly an aluminum support containing 0.3% or more of manganese.

Hereinafter, the present invention will be described in detail. The aluminum support is firstly alkali-etched. Preferred alkaline agents are caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium marminate, sodium gluconate and the like.
It is appropriate that the concentration is 0.01 to 20%, the temperature is 20 to 90 ° C., and the time is 5 seconds to 5 minutes, and the preferable etching amount is 0.01 to 5 g / m ² .

Particularly, in the case of an aluminum support having a large amount of impurities such as manganese, the amount of etching is suitably 0.01 to 1 g / m ² .

Subsequently, an alkali-insoluble substance (smut) remains on the surface of the alkali-etched aluminum plate, and therefore a desmut treatment may be performed if necessary.

The pretreatment is as described above, but subsequently, according to the present invention, AC electrolytic etching is performed in an electrolytic solution containing nitric acid as a main component. The frequency of the alternating electric field current is 10 to 20 Hz,
The nitric acid concentration is 3 to 150 g / l, more preferably 5 to 50 g / l,
The aluminum concentration in the electrolytic bath is preferably 50 g / l or less, more preferably 2 to 20 g / l, and if necessary, an additive may be added to this nitric acid, but in the case of mass production, It becomes difficult to control the liquid concentration.

The current density of the alternating current electrolysis current, 5~100A / dm ² but is appropriate and more preferably 10~80A / dm ^2. In addition, such conditions are appropriately selected depending on the quality required along with the quantity of electricity, the components of the aluminum support used, and the like.

Under these conditions, the pit diameter is 0.5 to 3 μm and the pit depth is 0.3.
Generates ~ 3 μm grain.

The power waveform is properly selected depending on the quality required and the components of the aluminum support used.
It is more preferable to use the special alternating waveform described in each of Japanese Patent Publication No. -19280 and Japanese Patent Publication No. 55-19191.

Preferably, the roughened aluminum is subsequently treated with an acid or alkali solution. Specifically,
In addition to the sulfuric acid described in Japanese Patent Laid-Open No. 56-11316, phosphoric acid or a mixed liquid of phosphoric acid and chromic acid is used. Further, a light etching treatment is carried out with an alkaline solution such as caustic soda as described in JP-B-48-28123 to remove the smut adhering to the surface. When removing the smut adhered with an alkali solution, the aluminum surface is etched, so that components insoluble in alkali remain.
Therefore, it is necessary to desmut again with an acidic solution (sulfuric acid, phosphoric acid, chromic acid, etc.).

Anodized layer 0.1 to 10 g / m ^2, more preferably 0.3~5g
It is better to form on the / m ² surface. It is preferable to perform alkali etching and desmut treatment before performing anodizing treatment.

The treatment conditions for anodization are not generally determined because they vary depending on the electrolyte solution used, but generally, the concentration of the electrolyte solution is 1 to 80% by weight, the liquid temperature is 5 to 70%, and the current density is 0.
A range of 5 to 60 A / cm ² , a voltage of 1 to 100 V, and an electrolysis time of 1 second to 5 minutes are suitable.

The thus-obtained aluminum plate having an anodized film is itself stable and excellent in hydrophilicity, so that a photosensitive coating film can be immediately provided on the aluminum plate, but if necessary, the surface can be further improved. Can be processed. For example, a silicate layer made of the alkali metal silicate described above 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 mg / m ² .

Next, a photosensitive coating film is provided on the aluminum support treated in this way, and after image exposure, development and plate making, it is set in a printing machine and printing is started.

〔Example〕

Example 1 An aluminum support of JIS3003 material containing 1.2% of manganese was immersed in a solution of a 3% aqueous solution of caustic soda warmed to 50 ° C. and etched so that the amount of dissolved aluminum was 0.1 g / m ^2. Then, the smut was removed and washed with water.

Then, 15 g / l of nitric acid solution was mixed with 5 g / l of aluminum ions, and the surface was roughened at a bath temperature of 50 ° C. using an alternating waveform current described in JP-B-55-19191. Electrolysis conditions
V _A = 15.2 V, V _C = 13.1 V Anode electricity quantity is set to 250 clones / dm ^2, and frequency is 11 Hz, 15 Hz, 20 Hz, 40
It was set under each condition of Hz, 60Hz, 80Hz and 100Hz, and the samples were named A, B, C, D, E, F and G, respectively. Then, after removing the surface smut, the anodic oxide film was 2.5 g / m ^{2 in} 20% sulfuric acid.
It was provided, washed with water, and dried. This is the substrate [A], [B],
These are [C], [D], [E], [F], and [G].

Comparative Examples 1 to 7 A JIS 3003 aluminum support containing 1.2% manganese was immersed in a solution of a 3% caustic soda solution heated to 50 ° C. and etched so that the amount of aluminum dissolved was 0.1 g / m ^2. After that, the smut was removed and washed with water.

Then, 15 g / l nitric acid solution was mixed with 5 g / l aluminum ion, and roughening was performed at a bath concentration of 50 ° C. using an alternating waveform current described in JP-B-55-19191. The electrolysis conditions are V _A = 15.2 V, V _C = 13.1 V, and the amount of electricity at the anode is
250 coulomb / dm ² and frequency is 0.1Hz, 0.3H
It was set to each condition of z, 1.0Hz, 5Hz, 9Hz, 150Hz, 400Hz, and named as H, I, J, K, L, M, N, respectively. Then, after removing the surface smut, the anodic oxide film was 2.5 g / m ^{2 in} 20% sulfuric acid.
It was provided, washed with water, and dried. This is the substrate [H], [I],
[J], [K], [L], [M], and [N].

Comparative Example-8 A JIS3003 aluminum support containing 1.2% of manganese was immersed in a solution of a 3% aqueous solution of caustic soda warmed to 50 ° C. and etched so that the amount of dissolved aluminum would be 0.1 g / m ² . The smut was removed and washed with water.

After that, 30g / l hydrochloric acid was mixed with 5g / l aluminum ion, and the amount of electricity at the anode was 250 coulomb / dm ² by alternating current of 15Hz. After that, smut on the surface was removed and 20% sulfuric acid was added. An anodized film was provided therein at 2.5 g / m ² , washed with water and dried. This is a substrate [O].

Substrates [A] to [O] thus prepared were coated with the following composition so that the coating weight after drying was 2.5 g / m ² to form a photosensitive layer.

Photosensitive solution composition Ester compound of naphthoquinone-1,2-diazide-5-sulfonyl chloride with pyrogallol, acetone resin (as described in US Pat. No. 3,635,709 Example-1) ... 0.75 g cresol novolak resin ... 2.00g Oil Blue # 603 (Orient Chemical) ・ ・ ・ 0.04g
Ethylene dichloride ・ ・ ・ 16g 2-Methoxyethylacetate ・ ・ ・ 12g The photosensitive lithographic printing plate thus produced was passed through a transparent positive film in a vacuum baking frame and passed from a distance of 1m to 3k.
After exposure with a metal halide lamp of w for 50 seconds, the sodium silicate with an S ₁ O ₂ / Na ₂ O molar ratio of 1.74 was 5.
After development with a 26% aqueous solution (PH = 12.7), printing was carried out by the usual procedure.

The printing machine used was Sprint 25 (manufactured by Komori Printing Machine Co., Ltd.).

In addition, the shape of the grain was observed with an electron microscope. The print results (dirt) are shown together in Table 1.

From the above results, Examples-1 to 7 according to the present invention can provide a printing plate having a good stain performance and suitable for mass production.

〔The invention's effect〕

The present invention is a method for producing a lithographic printing plate support, which comprises roughening an aluminum support in an electrolytic solution containing nitric acid using an alternating current having a frequency in the range of 10 to 20 Hz. With this, even if the support contains impurities, it is possible to uniformly generate a grain having a small pit diameter, and it is possible to manufacture a support for a printing plate having good stain performance, which is suitable for mass production.

Claims (2)

[Claims] 1. A lithographic printing plate support characterized by roughening an aluminum support in an electrolytic solution containing nitric acid using an alternating current having a frequency in the range of 10 to 20 Hz. Production method. 2. The aluminum support contains 0.3 manganese.
% Or more is contained, The manufacturing method of Claim 1 characterized by the above-mentioned.