JPS60203495A - Manufacture of lithographic printing aluminum base material and lithographic printing alminum substrate - Google Patents

Abstract

PURPOSE:To manufacture the titled substrate efficient in printing durability, by a method wherein after chemically processing the lithographic printing aluminum base material the surface of which is specifically embossed, its surface is roughened by electrolysis. CONSTITUTION:The lighographic printing aluminum base material is obtained by a method wherein the aluminum (alloy) plate of 99.5%min. in purity is rolled by using a roll and the concave part or convex part of 0.3-1.0mum in surface roughness and 10-100mum in diameter is formed on the surface. Then, after chemically processing this base material by dipping it into the aqueous solution of acid (for example: phosphoric acid) or alkali (for example: NaOH), the surface is roughened by electrolysis with asymmetrical alternating current under conditions of 2,000 coulomb max. in anodic quantity of electricity, 5-50V in voltage, 10-100A/dm<2> in current density and 0.4-1.25 in cathodic quantity of electricity/ anodic quantity of electricity in the aqueous solution containing aliminum of 1,000-40,000ppm and aluminum nitrate of 50-4,000ppm.

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 lithographic printing plates, but it is important to improve adhesion with the photosensitive layer provided thereon and to prepare lithographic printing plates using them. 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 chamber and is an essential step in preparing supports for lithographic printing plates. This grain chamber can be used for mechanical roughening methods such as ball graining, wire graining, fly graining, and plus 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. "Fundamentals of Lithographic Printing" published by Printing Jihosha (Author: Ichi Sugiyama, published December 1, 1965), pages 35 to 37 contain general explanations about the graining method, especially regarding abrasive slurry. It specifically describes a method for mechanically roughening the surface by using the same method.

Printing Magazine, July 1963 issue, pages 2-4, "Overview of Alumite Lithography" (Author: Tada Sano) describes a lithographic printing plate that is electrolytically roughened by alternating current using hydrochloric acid or nitric acid, and then anodized. The manufacturing method is described.

A graining method using a combination of these known surface roughening methods is also well known. L4 to US Patent No. 2,344,510! &
A lithographic printing plate in which the surface is mechanically roughened and then electrolytically roughened using hydrochloric acid, etc. to form complex grains on the surface in a β-superimposed manner (aml 卆se), and then anodized. The manufacturing method is described.

Japanese Patent Publication No. 57-16918 describes a method for manufacturing lithographic printing plates, which involves mechanically roughening, chemically etching with acid or alkali, and then electrochemically roughening and anodizing. has been done. 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 alternating waveform current in an acidic electrolyte. A lithographic printing plate and a method for manufacturing the same are described.

(Comparison between the present invention and the prior art) The present invention relates to an aluminum support for lithographic printing plates having a complex grain structure and an aluminum base material suitable for the manufacturing method of the support. A method for producing a new aluminum support for lithographic printing plates that has excellent round printing performance and is economically superior by further improving and developing the method for producing lithographic printing plates that have a grain structure consisting of plateaus and pits on the aluminum surface. It provides:

Said US Pat. No. 2,344,510 and Japanese Patent Application Laid-Open No. 1983-2
No. 8895 discloses a combination of ball graining, wire graining, brush graining, chemical etching and electrolytic roughening in a hydrochloric acid or nitric acid electrolyte as a means of constructing a plateau. 1st
A method for forming pits (secondary structures) and pits (secondary structures) is disclosed.These conventional mechanically roughened aluminum surface plateaus conceptually have the shape shown in FIG.
On the other hand, the plateau according to the present invention, which will be described later, is shown in Fig. 3 (A
) and CB), which are essentially different shapes.

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. In this way, a composite grained surface is obtained, the structure of which is conceptually shown in FIG.

On the other hand, as shown in FIG. 3(A), the support obtained by the method of the present invention has a smooth plane (a) unique to the aluminum plate and a surface that is microscopically smooth, but macroscopically smooth. A surface with concave portions (b), which would appear to be a rough surface, or a convex portion (b) as shown in Fig. 3(B).
Prepare an aluminum plate for lithographic printing plate (first invention of the present invention) having an appropriate distribution of C) and smooth surfaces (, i), and then form pits (secondary structure) into (a) (b). ) or (C) (, i) Fig. 4 (
A) (B) K A conceptual structure is obtained by electrochemical treatment.

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. Compared to other methods, it is possible to obtain a rough surface at a significantly higher speed and in a shorter time, and since multi-machine equipment is not required, printed clothing supports can be produced at low cost and with less variation in quality.

(2) According to the present invention, since no brush roll or abrasive is used on the grained surface of the aluminum plate, there is no contamination by brush fragments, aluminum polishing dust, abrasive residue, etc. Therefore, surface cleaning treatment using an acid or alkaline aqueous solution, etc., which is indispensable in conventional methods, is also necessary when applying m-, which is essential for homogenizing the electrolytically roughened surface. A very small amount of treatment for a short time to remove rolling oil etc. remaining on the surface is sufficient.

According to experiments by the inventors, in order to uniformly overlap an electrochemically rough surface in brush graining using pumice slurry, the brush grained surface must be dissolved and cleaned in the range of 2 to St/d. iS that needed to be changed to 2f/W when using the present invention? Below, for example, only o, aq
Uniform bits can be superimposed on the surface by a subsequent electrochemical roughening step with a dissolution amount of the order of t/-. This can greatly reduce the amount of acid or alkaline chemicals consumed in conventional etching, and at the same time facilitates drainage treatment, which is highly economical.

(3) The advantage that can be called the greatest feature of the present invention is related to the degree of primary structural assembly of the aluminum plate used. As shown in FIG. 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 obtain a completely uniform rough surface by transferring the roughened roll surface, a highly uniform rough surface is set on the roll surface, and advanced rolling is required to ensure that the rough surface is accurately transferred. Conventionally, there has been a problem that this method is not suitable for practical use because it requires special techniques and the extremely rapid wear of the rough surface of the roll during rolling makes it impossible to accurately transfer the rough surface.

In contrast, in the present invention, in order to obtain an aluminum support for a lithographic printing plate, a uniform rough surface is obtained by superimposing bits as a secondary structure using an electrochemical method. Printing that is superior in stain resistance and printing durability compared to printing plates made by conventional methods, and superior in stain resistance and printing durability to the method described in Japanese Patent Publication No. 57-16918. Since a plate is obtained, in the present invention, the rough structure of the roll surface does not require a high degree of uniformity in order to impart the primary structure shown in FIG. 6, is easy to manufacture, and is resistant to wear. It is practical because it has a wide allowable range and can form the surface of a large amount of aluminum plates for printing plates.

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

Although pure aluminum plates and various aluminum alloy plates are used in the present invention, alloy plates with a purity of 99.5 or higher, such as JISA1050 material, are particularly preferred. Other aluminum alloy plates include JISA 11 Q Q
material, FeO,2'FJs~1.0% and Bn, In
, Ga, and Zn at 0.0
'05-0.196 aluminum alloy, further Myo, 1%-0.6% and CuO01-2%
Aluminum alloy containing one or more of My
Aluminum alloys containing O13-1.5 and SiO, 15-0.8, and aluminum alloys further containing one or more of o, os-o, 3% Mn and Cr, etc. . These alloys have appropriate hardness, which makes them convenient for transferring roughened roll surfaces, and they also have the property of making the rough surface uniform through subsequent electrochemical treatment. 2
Bits of the following structure can be generated with optimal size and distribution in the printing plate.

Grained aluminum plates may be subsequently subjected to anodizing treatment, but the alloy components contained in these aluminum alloy plates do not dissolve and fall off during the anodic oxidation coating treatment, resulting in a uniform anodized coating without defects. Because it is formed, a printing plate that is resistant to staining and has long printing durability can be obtained.

A rolling roll for roughening an aluminum plate is obtained, for example, by roughening the surface of a steel roll by dry or wet sandblasting. Alternatively, the surface may be roughened by grinding with a whetstone containing abrasive grains, paper, or by chemical or electrochemical etching. 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. Qμ, diameter 10-100μ
It has a concave or convex structure, and a portion that occupies an area of approximately % or more around the center of the concave or convex portion has a flat structure when viewed microscopically.

The surface roughness is measured using a stylus type surface roughness meter and expressed as center line average roughness (Ha). 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 is large, the printing sensitivity decreases, and the photosensitive layer in non-image areas cannot be removed within a predetermined time. will occur.

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

The surface of the aluminum plate thus obtained is then chemically treated. This is generally done by immersion in an aqueous acid or alkaline solution. Specific examples of the acid or alkali aqueous solution include acid aqueous solutions such as phosphoric acid, sulfuric acid, and nitric acid, and alkaline aqueous solutions such as sodium hydroxide, potassium hydroxide, sodium triphosphate, and sodium aluminate. These acids or alkalis can be used singly or in combination of two or more.

The amount of aluminum dissolved in the chemical treatment of the present invention is basically characterized by being extremely small, and can be freely changed within the range of usually 0.1 to s, y/-. Economically, 0.5 to 1.8t/pr? is sufficient.

The aluminum plate treated in this way is subsequently subjected to electrochemical roughening. The feature of the electrochemical surface roughening in the present invention is that pits are distributed in a superimposed manner on the -dimensional surface, as previously illustrated in FIG.

The bit has an opening diameter of 0.3 to 3μ, and its depth is 0.
．． The overlapping density is approximately 1 to 1 μm, and the overlapping density must be adjusted according to the required performance (mainly printing durability) of the printing plate. What should be noted is that even when such pits are superimposed, the value of surface roughness (Ha) obtained by a stylus roughness meter hardly changes.

As a result of searching for the conditions for electrochemical surface roughening that best suited the above purpose, the present inventors found that the electrolyte
0000 ppm of nitric acid and 50% of aluminum nitrate.
Using an aqueous solution containing ~4000 ppm, use a general commercial symmetrical alternating current as a power source, or use the power source shown in Figure 5 (A
), using the alternating waveform shown in (B), the voltage 5~SOV within the range where the anode special electricity amount does not exceed 2000 coulombs.
.

Current density 10-100A/d? F1″, cathode special electricity quantity/
It has been found that the desired surface can be obtained when the amount of electricity at the anode is in the range of 0.4 to 1.25. In particular, when the above-mentioned asymmetrical alternating current is used, there is an advantage that a printing plate with excellent printing durability can be obtained even with a low amount of electricity.

When an aqueous solution containing mainly hydrochloric acid or aluminum chloride is used as an electrolyte, the generated bit diameter tends to be large and non-uniform, which is inappropriate for achieving the desired uniform overlapping of bits. .

(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 commonly used as an electrolyte for anodizing. 4F with sulfuric acid 10~ as described in British Patent No. 1,412,768.
It is preferable to use a method of anodic oxidation using a DC current at a high current density using a 30% carbon steel.

The anodized aluminum plate is further described in U.S. Pat.
As described in No. 14066, it can be used after being subjected to multiple treatments such as immersion in an aqueous solution of an alkali metal silicate, for example, 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 1 Pure 999.59g aluminum sheet (thickness 0.35
1+1I11) was semi-gloss blasted with a steel ball of Meshna 120 at a pressure of 5 Y/2.
By applying embossing rolling at a plate thickness reduction rate of 15 inches, a first plate with an average surface roughness of 0.68μ and an average diameter of uneven portions of 65μ is obtained.
An aluminum plate with the following assembled surface structure was made. The amount of aluminum dissolved is 1.5 using a 20% caustic soda aqueous solution.
It was chemically treated so as to have f/-, washed thoroughly with running water, pickled with 25 g of nitric acid aqueous solution, and rinsed with water. This aluminum plate was electrochemically roughened by an alternating waveform current using a rectangular wave shown in FIG. 5(A) under the conditions shown in Table 1 below.

Subsequently, the surface was cleaned by immersion in a 50°C aqueous solution of 15% sulfuric acid for 3 minutes, and then anodized by direct current in a 20% sulfuric acid solution to form an oxide film of 2.4 f/m. It was created.

For comparison, a sample was prepared in the same manner as Sample A, except that instead of embossing in Sample A, a pumice stone-water suspension and a rotating nylon brush roller were used to form a grain pattern to form a primary texture structure. B was created.

A photosensitive liquid having the composition shown below was applied to the sample prepared in this manner, with a dry coating amount of 2. sy-, /-.

The photosensitive lithographic printing plate thus obtained was imagewise exposed for 60 seconds from a distance of 1 m using a 3-certified metal halide lamp, and the Si
With a molar ratio of 02/Na20 of 1.2, 5i02
The film was developed with an aqueous solution of IJ (silicic acid having a content of 1.5%).

When the lithographic printing plate thus obtained was used for printing according to the conventional procedure, the sample prepared according to the method of the present invention obtained good results in terms of printing durability and stain resistance, as shown in Figure 2 below. .

Table 1 Table 2 Note that samples prepared in the same manner as Sample A above, except that the electrolytic surface roughening treatment and subsequent cleaning treatment were not performed, had good stain resistance, but the printing durability was not as good as that of Sample A. It was inferior.

Example 2 Aluminum sheet with a purity of 99.5% (thickness 0, 25%)
m) using a rolling mill at a speed of soom/min of 0.24+
+ m. At this time, the rolling roll has a grain size of 560
A steel roll that had been subjected to abrasive blasting using a silicon carbide abrasive at a pressure of 5 kg/m2 was used. In this way, an aluminum plate having a bottom surface structure with uneven portions having an average surface roughness of 0.44μ and an average diameter of 20μ was produced. caustic soda 20
The amount of aluminum dissolved using an aqueous solution is 0.82/-
After chemical treatment was carried out so that the resultant material was thoroughly washed with running water, it was pickled with a 25φ nitric acid aqueous solution and washed with water. This aluminum plate was subjected to two types of electrochemical roughening shown in Table 3 below, washed with water, and then immersed in a 50° C. aqueous solution of 15 qb sulfuric acid to clean the surface. Thereafter, anodic oxidation treatment was performed by direct current in an aqueous solution of 20% sulfuric acid to form an oxide film of 1.8 f/-. Then, add 1 liter of sodium silicate aqueous solution at 70°C.
Samples C and D were prepared by immersion for 1 minute, washing with water, and drying.

For comparison, sample D was made in the same manner as sample D, except that instead of embossing, a pumice stone-water suspension and a rotating nylon brush roller were used to grain and form the primary embossing structure. Sample E was created.

Samples C%D and E prepared in this manner were coated with a photosensitive solution having the following composition so that the dry weight was 2. It was applied so that it became oy/R.

The thus obtained photosensitive lithographic printing plate was exposed to a light source of Fuji Film P, S, and Light (Toshiba metal halide lamp Mυ2000-2-DL type = 3N@) from a distance of 1 m through a transparent negative film in a vacuum printing frame. Also, Fuji Photo Film (what is sold) is 950
After exposure for seconds, the plate was developed with a developer having the composition shown below and gummed with an aqueous gum arabic solution to prepare a lithographic printing plate.

When the lithographic printing plates thus obtained were printed according to conventional procedures, as shown in Table 4 below, the samples prepared according to the method of the present invention showed excellent performance in terms of printing durability and resistance to staining. .

Table 4 In addition, using a polishing agent of silicon carbide (particle size 360),
．． Purity is 99.5% using a steel roll that has been blasted under a pressure of 5 kg/ctn2 for a sufficient period of time.
An aluminum sheet (in order of plate thickness 0.25) was embossed to produce an aluminum plate having a primary surface structure with an average surface roughness of 0.25μ and an average diameter of 20μ.However, steel rolls were used. (The roll surface was worn out after approximately 3000 m of rolling due to significant stickiness of aluminum particles on the surface, making it unsuitable for mass production.) Using an aluminum plate with a surface roughness of 0.25μ obtained at the initial stage of rolling, a printing plate prepared in the same manner as Sample C above after chemical treatment with an aqueous caustic soda solution has extremely poor printing durability compared to Sample C. Met.

[Brief explanation of the drawing]

Fig. 1 Primary grain shape model according to the prior art Fig. 2 Composite grain shape model according to the prior art Fig. 3 Primary grain shape model according to the present method Figure 4 Composite grain shape model according to the present method Figure 5 Power supply waveforms used for electrolytic surface roughening Figures 6-7 Surfaces of Samples A and B of Example 1 Photographs of Samples A and B (1) Akira Ryo Hagiwara - Figure 1 Figure 5 (Method) Hand-reading correction July 1980//rl Manabu Shiga, Commissioner of the Patent Office1, Indication of case Patent Application No. 58197 of 19822,
Title of the invention Process for producing aluminum substrates for lithographic printing and aluminum supports for lithographic printing plates 3, Relationship to the case of the person making the amendment Patent applicant address 210-4 Nakanuma, Minamiashigara City, Kanagawa Prefecture, Agent
Address 16-2 Toranomon Chiyoda Building, Minato-ku, Tokyo Telephone (504) 1894 Name Patent attorney (
7179) 1) Akira C and 1 other person) 5. Date of amendment order. June 6, 1982 (Shipping date: 26th June, 1982)
6. The number of inventions will not increase due to the amendment. The description "It is an OEM photograph." has been corrected as follows. [Figure 1 shows a primary grain shape model according to the prior art, Figure 2 shows an overlapping grain shape model according to the prior art, and Figure 6 shows a primary grain shape model according to the method of the present invention. 4 shows a composite grain shape model according to the method of the present invention, FIG. 5 shows a source waveform used for electrolytic surface roughening using the method of the present invention, and FIGS. 1 is an SEM photograph showing the metallographic structures of the surfaces of Samples A and B of Example 1. ”

Claims (3)

[Claims] (1) The plate surface essentially has a surface roughness of 0.3 to 1.0μ
An aluminum substrate for a lithographic printing plate, characterized in that unevenness with an average diameter of 10 to 100 μm is formed by embossing. (2) Emboss the surface of the plate to form irregularities with a surface roughness of 0.3 to 1.0μ and an average diameter of 10 to 100μ, which are then chemically treated with acid or alkali, and then 1. A method for producing an aluminum support for lithographic printing plates, characterized by subjecting it to stain removal and surface roughening by symmetrical alternating current. (3) Emboss the surface of the plate to essentially form irregularities with a surface roughness of 0.3 to 1.0μ and an average diameter of 10 to 100μ, which are then chemically treated with acid or alkali, and then 1. A method for producing an aluminum support for a lithographic printing plate, which comprises removing stains and roughening the surface by asymmetrical alternating current in a range where the ratio of cathodic charge to anodic charge is 0.4 to 1.25.