JPS60203497A - Manufacture of aluminum base material for lithographic printing plate and aluminum substrate for lithographic printing plate - Google Patents

Abstract

PURPOSE:To manufacture the titled substrate efficient in printing durability and water retention, by chemically etching the surface of specific aluminum alloy plate which is embossed. CONSTITUTION:The lithographic printing aluminum material having the unevenness of 0.3-1.0mum in surface roughness and 10-100mum in average diameter is obtained by embossing the surface of aluminum alloy plate containing 0.3- 1.5wt% Mg, 0.15-0.8wt% Si, 0.05-0.3wt% Mn or Cr if necessary and inevitable impurities. Then, the pit of 1-5mum in aperture diameter and 0.1-0.8mum in depth is formed by chemically etching the surface of this base material by 6-100g per m<2> with acid (for example: nitric acid).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lithographic printing plate substrate and a method for producing a lithographic printing plate support using the substrate.

(Prior Art) Aluminum plates have conventionally been widely used as supports for planographic printing plates, but it is important to improve adhesion to the photosensitive layer provided thereon and to make planographic printing plates made using the aluminum plates. The surface of the aluminum plate is roughened to improve water retention in the non-image area (the exposed area of the support surface that receives dampening water and repels oil-based ink used during printing). It is customary to be This surface roughening treatment is called a grain pattern and is an essential step in preparing supports for lithographic printing plates. This grain pattern is produced by mechanical roughening methods such as ball graining, wire graining, brush graining, and blast graining.
Electrolytic surface roughening method involves electrochemical etching in acid or neutral aqueous solution, or chemical surface roughening method involves chemically etching in acid or alkali using special aluminum alloy material. Are known. Published by Printing Jihosha, "Fundamentals of Lithographic Printing" (Author: H. Sugiyama, published December 1, 1965), pages 35-37 contain general explanations on the graining method, especially on abrasive slurry. It specifically describes a method for mechanically roughening the surface by using the same method.

Print magazine, July 1963 issue, pages 2-4, ``One-cup theory of alumite lithography'' (Author: Tada Sano) states that the surface is electrolytically roughened by alternating current using hydrochloric acid or nitric acid, and then anodized. A method of manufacturing a lithographic printing plate is described. Tokuko Showa 5
No. 4-42284 describes a method for producing a lithographic printing plate in which an aluminum alloy plate containing 1.6 to 2.5% manganese is chemically roughened with an alkali.

A graining method using a combination of these known surface roughening methods is also well known. U.S. Patent No. 2,544,510 discloses that after mechanical roughening, electrochemical roughening is performed using hydrochloric acid or the like to form superimposed composite grains on the surface, and then anode A method for producing a lithographic printing plate that undergoes an oxidation treatment is described.

Japanese Patent Publication No. 57-16918 describes a method for producing lithographic printing plates, which involves mechanical roughening, chemical etching with acid or alkali, and then electrochemical roughening and anodic oxidation treatment. ing. Also, Japanese Patent Publication No. 56-2889
No. 3 has a grain structure with plateaus and pits on the aluminum surface by combining mechanical roughening, chemical etching, and electrochemical roughening using an asymmetric alternating waveform current in an acidic electrolyte. A lithographic printing plate and method of making the same are described.

(Comparison between the present invention and the prior art) The present invention relates to an aluminum support for a lithographic printing plate having a complex grain structure and an aluminum base material suitable for a method for manufacturing the support.
In particular, we have further improved and developed the manufacturing method for lithographic printing plates that have a grain structure consisting of plateaus and pits on the aluminum surface.
The object of the present invention is to provide a novel method for producing an aluminum support for lithographic printing plates, which has excellent printing performance and is economical.

The above, U.S. Patent No. 2.544.510 and Japanese Patent Application Laid-Open No.
In No. 28895, Sibrado (
A method for constructing a primary structure) and a pit (secondary structure) is disclosed. These conventional mechanically roughened aluminum surface plateaus conceptually have the shape shown in FIG.
The shape shown in Figure (4) and (Bl) is essentially different.

Furthermore, when using the methods described in these two patent documents, pits can be electrochemically superimposed on the smooth surface of this primary structure from a microscopic perspective without damaging the primary structure. By doing this, a composite grained surface is obtained, the structure of which is conceptually shown in FIG.

On the other hand, the support obtained by the method of the present invention, as shown in FIG. If you look at it, there are concave portions (bl) that appear to be rough, or convex portions (as shown in Figure 3 CB+).
An aluminum plate for lithographic printing plate (first invention of the present invention) having an appropriate distribution of C1 and smooth surface (d) is prepared, and the surface of the aluminum plate is coated with an acid in the range of 6 to 100 f/m2. After chemical etching (al (1)l
By distributing pits (secondary structure) in a superimposed manner on both surfaces of t or (cl (d)), a structure as conceptually shown in Fig. 4 (4) and (B) is created. It is characterized by

The invention has the following advantages compared to the prior art.

(1) When manufacturing the surface structure shown in Figure 3, a roll with a roughened surface structure is used and the primary structure is formed by transferring this onto the surface of an aluminum plate. It is possible to obtain a rough surface at a significantly higher speed and in a shorter time than with other methods, and since it does not require complicated equipment, it is possible to produce supports for printing plates at low cost and with little variation in quality.

(2) The method according to the present invention involves forming a concave or convex structure with a surface roughness of α3 to 1.0 μm and an average diameter of 10 to 100 μm using an embossing roll, and then chemically etching the surface with acid (see FIG. 4). It forms pits with an average diameter of 1 to 5 μm and an average depth of 0.1 to 0.8 μm as shown in Al, (Bl).

Therefore, scratches, plaque wear debris, and abrasive residues caused by conventional mechanical graining are trapped.
It has a surface structure that is resistant to staining, so it has excellent water retention, and when it is then chemically etched with acid to form overlapping composite grains, it has sufficient printing durability and excellent water retention. A support for a lithographic printing plate can be obtained.

(3) The aluminum plate used in the present invention is prepared by transferring a previously roughened roll surface by rolling, but this process does not require a completely uniform roughened surface. In order to achieve a completely uniform rough surface by transferring the roughened roll surface, it is necessary to set a highly uniform rough surface on the roll surface and to use advanced techniques to ensure that the rough surface is accurately transferred. Conventionally, this method has had the problem that it is not suitable for practical use because it requires a rolling technique and the extremely rapid wear of the rough surface of the roll accompanying rolling makes it impossible to accurately transfer the rough surface. In contrast, in the present invention, fine pits are superimposed by acid etching on an aluminum plate having a primary structure formed by embossing to obtain an aluminum support for a lithographic printing plate having a uniform rough surface. Therefore, in the present invention, the first
In order to impart the following structure, the rough structure of the roll surface does not require a high level of uniformity, is easy to manufacture, and has a wide tolerance for wear, making it suitable for mass production and practical. It is.

(4) According to the present invention, a support for a lithographic printing plate having a good composite grain can be obtained without electrolytic graining. In the electrolytic graining method, the depth and shape of the grain can be changed to some extent by changing the amount of electricity, but generally a large amount of electricity is required to create a grain suitable for lithographic printing plates, which increases the price and time. It has the disadvantage that it costs a lot of money.

On the other hand, in the case of "non-explosion", there is no need to perform %i electrolytic graining, so there is no such drawback, and the chemical etching method using acid has a simple process and the process is carried out continuously in the form of a strip. ), which is technically advantageous, especially when treating both sides of the support.

(Details of the present invention) The manufacturing method of the present invention will be explained in detail below.

The aluminum plate used in the present invention has Mg 0.3 to 1
．． 5% by weight, Si [1.15 to 0.8% by weight, balance A/
and unavoidable impurities, or an aluminum alloy further containing α05 to 03% by weight of Mn or Or.

Mg and Sl are blended for the purpose of obtaining strength required as a lithographic printing plate support and for forming intermetallic compounds such as Mg and Eli in the manufacturing process of the alloy plate. This intermetallic compound is selectively dissolved by chemical etching with the acid of the present invention, thus forming pits. Therefore, it is desirable that the Mgzsi compound be formed with an appropriate size and distribution. Mg and 8
Even if the ratio of 1 is 2:12 by weight in terms of the number of atoms, it is convenient to form the Mg251 compound if the ratio is 2:1.

If Mg is less than a3% (si is 0.15%), the amount of Mg and 81 compounds formed will be insufficient; on the other hand, if Mg is less than 1.5% (
If the sl exceeds 0.8%), the 'gtEIi compound will be formed in excess, leading to coarsening of the particles, both of which are unfavorable for obtaining a rough surface suitable as a lithographic printing plate support. In the present invention, the size of the Mg25i compound particles is 0.1 to 2.
Although it is desirable to control the thickness to about μ, this can be achieved by appropriately selecting the heat treatment conditions during rolling. Note that even if the ratio of Mg to Sl is deviated from 2:1, excess Mg or Sl will be dissolved in aluminum, so it is not harmful at all.

Addition of Mn or Or has the effect of uniformly forming and distributing Mg and Si compounds. If the amount added is less than 0.005, the effect is small, while if it exceeds 0.3%, Mg2S
This is not preferable because it forms intermetallic compounds other than i and inhibits solubility during chemical etching with acid.

The aluminum ram alloy plate of the present invention is subjected to embossing followed by chemical etching with an acid for a fourth time.

It has the characteristic that the surface shape shown in ψ) can be easily formed. On the other hand, when a commercially available aluminum alloy material such as J-Ko SA 1050.1100°3003 is used, the desired surface shape cannot be obtained even if the chemical etching with the acid of the present invention is performed. , sufficient printing durability cannot be obtained.

Furthermore, since the aluminum alloy plate of the present invention has appropriate hardness, it is convenient for transferring a roughened roll surface during embossing.

Grained aluminum plates may be subsequently subjected to anodizing treatment, but the alloy components contained in the aluminum alloy plate of the present invention do not dissolve and fall off during the anodic oxidation film treatment, resulting in uniform anodization without defects. Since a film is formed, it is possible to obtain a printing plate that is resistant to stains and has printing durability.

A rolling roll for roughening an aluminum plate is obtained, for example, by roughening the surface of a copper roll by dry or wet sandblasting. Alternatively, the surface may be roughened by grinding with a whetstone or paper containing abrasive grains, or by chemical, frost, or vapor chemical etching methods. In order to prevent roll surface wear, it is also effective to roughen the surface and then harden it by applying chrome plating, etc. In particular, when the surface is roughened by sandblasting, it combines with surface hardening during processing to prevent wear. A rough surface roll with excellent properties can be obtained.

The surface of the aluminum plate rolled using these rolls has a surface roughness of 0.3 to 1.0μ and a diameter of 10 to 100μ.
It has a concave or convex structure, and a portion occupying an area of about 4 or more around the center of the concave part or convex part has a flat structure from a microscopic point of view.

The surface roughness is measured using a stylus type surface roughness meter and is expressed as center line average roughness (H-). If the surface roughness is less than 0.3 μm, the adhesion between the photosensitive layer and the support will decrease, making it difficult to obtain the desired printing durability. On the other hand, the surface roughness is 1.0
When μ is larger, the thickness of the photosensitive layer required to uniformly cover the surface of the support becomes thicker, resulting in lower printing sensitivity and the problem that the photosensitive layer in non-image areas cannot be removed within a predetermined time. will occur.

Further, if the average diameter of the unevenness is less than 10 μm or exceeds 100 μm, the printing durability decreases.

The surface of the aluminum plate thus obtained is then chemically etched with acid.

Examples of acids that can be used include nitric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and hydrofluoric acid, and these acids can be used singly or in combination.

In the present invention, the chemical etching treatment with acid is the fourth
This is done in order to obtain a surface structure as described with respect to Figure (4), a3). Specifically, by embossing, the surface roughness is essentially 0.3 to 1.0μ, and the average diameter is 10 to 100.
The surface of the aluminum plate on which the unevenness of μ is formed is heated with acid at a rate of 6 to 100 tons/2, preferably 10 to 30 W/m.
2. Chemical etching is sufficient. Conditions for acid etching are known to those skilled in the art and can be selected arbitrarily.

The printing durability of the printing plate obtained by such chemical etching treatment is improved.

The bits formed by acid etching have an opening diameter of 1 to 5μ, and the depth is about 0.1 to (18μ), and the overlap density is determined by the required performance of the printing plate (mainly printing durability). It should be noted that even when such pits are superimposed, the value of surface roughness (Ha) obtained by a stylus roughness meter hardly changes. There is no such thing.

(Details of Additional Techniques of the Present Invention) The aluminum plate treated as described above may further be provided with an anodized film. Sulfuric acid is generally used as the electrolytic solution for the open electrode oxidation treatment. Especially the first British patent
．． Sulfuric acid 10-3 as described in No. 412.768
A method of anodizing using a DC current of 0% at a high current density is preferred.

Anodized aluminum plates are further described in U.S. Patent No. 2.
As described in No. 714.066, it can also be used after being treated by a method such as immersion in an aqueous solution of an alkali metal silicate, such as sodium silicate. On the lithographic printing plate support according to the present invention, a conventionally known photosensitive layer can be provided to cover a photosensitive lithographic printing plate.

The method for producing a lithographic printing plate support according to the present invention will be described in detail below based on Examples.

EXAMPLE Five types of aluminum alloy plates (plate thickness 0.35 mm+) according to the present invention shown in Table 1 below were manufactured, and semi-gloss plaster was applied to them at a pressure of 25 kg/cy++'' using an r-ball with mesh≠120. Emboss processing was performed using a processed @-made roll to obtain a roughened plate having a thickness of 0.30 am + average roughness Q of 55 μm and an average diameter of uneven portions of 70 μm.

This embossed aluminum alloy plate was mixed with 1/2 water, 300-II nitric acid and 100-II phosphoric acid! 7! Etching was performed using an etching solution consisting of 20 f/m" so that the dissolved amount was 20 f/m".Next, it was neutralized with an alkaline aqueous solution, and then thoroughly washed with water.In this way, the average diameter formed by embossing was 70 μm. On the rough surface of
~3μ pits are formed, and the overall surface phase is α56
It was possible to obtain an aluminum alloy plate having μ.

Next, samples A, B, O, D, and E were subjected to direct current anodization treatment in a 15% sulfuric acid aqueous solution to form an oxide film of 2.4 t/m2. And so.

For comparison, a sample F was obtained by using a J-Ko SA 1050 aluminum plate (plate thickness o, 35 mm) and surface-treated in the same manner as above. The average roughness of sample F was C1.51μ.

Table 1 (Unit: % by weight) A photosensitive liquid having the composition shown below was applied to the sample thus prepared so that the dry coating amount was 2.5 t/m''.

Photosensitive solution The thus obtained photosensitive lithographic printing plate was imagewise exposed for 60 seconds from a distance of 1 fn using a 3 kW metal halide lamp.
The molar ratio of SiCl/Na2O is 1,2, and 5102
The film was developed with an aqueous sodium silicate solution having a content of 1.5%.

When the lithographic printing plates thus obtained were used for printing according to conventional procedures, the results shown in Table 2 below were obtained.

Table 2 From the results in Table 2, samples A to E of the present invention have printing durability,
It can be seen that while sample F, which uses a conventional alloy phase, is excellent in both stain resistance and printing durability is inferior.

[Brief explanation of the drawings] Figure 1 is a primary grain shape model according to the prior art, Figure 2 is a composite grain shape model according to the prior art, Figure 3 (4),
03) is the primary grain shape model according to the present invention, FIG.
), (Bl respectively shows the composite grain shape model when the primary grain shape according to the present invention is acid-etched. Representative 1) Akira Representative Ryo Hagiwara - Figure 2 Figure 4 (A) (8 )

Claims (2)

[Claims] (1) Mg 0.3 to 1.5% by weight, Si 0.15 to
0.8% by weight, the balance A/ and unavoidable impurities, or an aluminum alloy further containing 0.05 to 0.3% by weight of Mn or Or. An aluminum substrate for a lithographic printing plate, characterized in that unevenness with a surface roughness of 0.3 to 1.0 μm and an average diameter of 10 to 100 μm is formed by embossing. (2) Mgα3-1.5% by weight, Si'115-08
% by weight, balance A/ and an aluminum alloy consisting of unavoidable impurities, or the alloy further contains 0.05 to 0.3 % M
The surface of a plate made of an aluminum alloy containing n or Or is essentially given a surface roughness of 0.5 to 1 by embossing.
．． 0 μ, an average diameter of 10 to 100 μ is formed, and the surface is chemically etched by 6 to 10,097 m by removing it with acid.
A method for producing an aluminum support for a lithographic printing plate, comprising: