JPS6036196A - Base for planographic printing plate - Google Patents

Abstract

PURPOSE:To simplify a graining process, by a method wherein a surface of an Al plate is provided with oblong form press-recessed parts in a density not lower than a specified value so that the recessed parts partially overlap with each other to form a wavy patterns, and specified minute recessed parts are provided thereon by chemical etching. CONSTITUTION:The surface of the Al plate is provided with the oblong form press-recessed parts in a density of not lower than 200 pieces/mm.<2> so that the recessed parts partially overlap with each other to form a wavy pattern, and then minute recessed parts with an average pitch of 1-10mum are provided thereon by chemical etching. Roughneing of the surface of the Al plate is conducted by, e.g., a pressure roll the surface of which is previously roughened, whereby the surface of the Al plate is provided with the oblong press-recessed parts in a high density so that fronge parts thereof partially overlap with each other to form a wavy pattern. In this case, the shape and the density of the oblong form recessed parts are associated with adaptability for a planographic printing plate, and are adjusted to within respective predetermined ranges. The density of the oblong form press-recessed parts is preferably not lower than 200 pieces/mm.<2>, desirably, 1,000-10,000 pieces/mm.<2>.

Description

[Detailed description of the invention] The present invention relates to a support for a lithographic printing plate.

Aluminum is currently widely used as a substrate for making lithographic printing plates. Aluminum lithographic printing plates are
The surface of the aluminum plate is roughened to form grains, a photosensitive composition is applied, and this is exposed. - Obtained by leaving the image-retaining area to be developed and printed as a resist.

The purpose of forming grains on the aluminum plate surface is twofold: firstly, to provide the printing plate with adequate water retention during printing operations, and secondly, to improve the contact between the resist coating and the aluminum plate surface. It is important to improve bamboo properties and provide sufficient printing durability.

The 411 relationship between the shape of the grain and the suitability for various types of printing is multi-layered, and there is still no systematic theory {=J} that has been developed yet, but it is believed that the concave 41-1 structure with a relatively coarse pitch retains water in the soil. It is generally believed that the concave transverse pitch of the comparative fishing machine is mainly related to adhesion. Based on this kind of coloring, Japanese Patent Application Laid-open No. 54-63902 discloses that after brush polishing, chemical cleaning to chemically remove abrasives and aluminum debris, and electrochemical roughening. A method for obtaining microscopic grains with a large and uniform average roughness by J is described.

The grain obtained by such a method is excellent in terms of water retention and resist adhesion as a printing plate, but it has the problem of complicating the manufacturing process. In other words, brush r11) polishing requires considerable skill in adjusting the machine and polishing agent, and furthermore, after the polishing process, the brush r11) may bite into the aluminum surface.
Chemical cleaning must be performed to remove abrasives and aluminum debris.

With this in mind, the present inventors have streamlined the process of brush polishing, chemical cleaning, and electrolytic etching, and have developed a method that does not impair its properties as a lithographic printing plate support.
The present invention was achieved as a result of repeated research aimed at finding a new method for surface treatment of aluminum plates.

That is, the present invention forms four oval pressed parts on the surface of an aluminum plate at a density of 200 pieces/l' or more, and a part of the pressed recesses overlaps to form a wavy pattern. Then, fine concave portions having an average pitch of 1 to 10 μm are formed on the support by chemical etching.

The grained board of the present invention is characterized by having a fine concave structure with a small pitch formed by chemical etching on top of the concave structure with a specific pitch formed by pressing.

The aluminum plate used in the present invention includes a pure aluminum plate and an aluminum alloy plate. Various aluminum alloys can be used, such as II
m, copper, manganese, magnesium, chromium, zinc, lead,
An alloy of aluminum and metals such as iron, titanium, and nickel is used.

The rough surface of the aluminum plate can be formed using, for example, a rolling mill as described below. That is, a rolling mill for rolling aluminum plates (for example, tJ4II
By roughening the surface of the roll (I) and rolling the aluminum plate through this roll, it is possible to transfer the rough shape of the roll surface onto the aluminum plate surface. The roughened steel roll is, for example, 10
Fine particles (for example, silica, oxides such as alumina, steel, etc.) with a size of 0 to 1000μ are mixed with an impeller at a rotation speed of 1500 to 300.
0ppm, grid input ft! +1 from 100 to 500
/1n.

Production can be carried out by spraying onto rotating rolls at a shot interval of 1 to 30 minutes.The rolling reduction rate when rolling an aluminum plate is 3 to 50 per pass.
% range, and it is also possible to carry out rolling treatment multiple times as necessary. The rolled aluminum plate is
Four oval parts are arranged closely on the surface, and the fringes partially overlap to form a wavy pattern. At this time, the shape and density of the four parts of the ellipse and shape are related to the suitability of the lithographic printing plate, and these values are controlled within a certain range.

First, the density of the oval press recess is 20011f! /+
t, 660 11112 or more, preferably 200 ~ 廿≠less pieces/ll
lI2, more preferably 1, 0.00-, -10
, 000 pieces/1111'. If the density of the press recesses is lower than 2009A/lll12, the adhesiveness between the resist and the aluminum surface will decrease, and the water retention will also decrease.

Furthermore, in the present invention, it is important that the elliptical press recesses partially overlap and that their fringes form a wavy pattern, as shown in Example 2 (FIG. 1), which will be described later. .

The pattern obtained by conventional brush polishing, for example, is shown in Figure 3. A +-like pattern or a linear 1fi-like grain shape as shown in Comparative Example 1 (FIG. 2), which will be described later, is less likely to cause stains.

The shape of the press recess is formed by rolling.

In general, the long axis of the oval is parallel to the direction of coil stretching (j,
The short axes are arranged in a direction perpendicular to the stretching direction.

When the average length of the long sleeves is preferably in the range of 10 to 140μ, and the average length of the short axis is preferably in the range of 7 to 80μ,
A lithographic printing plate with good adhesion of the resist to the aluminum surface, excellent dot reproducibility, and water retention is available. If the size of the four oval parts is larger than this, the adhesiveness
Both small point reproducibility decreases.

Also, regarding the depth of the four parts, the center line average roughness Ra I
When J is in the range of 0.3 to 1.5 μ, it is preferable in terms of the balance between water retention and small dot reproducibility.

If it is 0.3μ or less, water retention is insufficient, and 1.
If it is 5μ or more, small point reproducibility will decrease.

In the present invention, after forming the elliptical press recess, a chemical etching process is further performed to form four small bits.

In other words, if chemical etching is performed after pressing,
The surface gloss is reduced, the plate-made image becomes easier to see (small dots are easier to see), and the water level during printing becomes easier to see, improving work efficiency.

Chemical etching bath components include hydrofluoric acid, nitric acid,
Some are known to be mainly based on acids such as sulfuric acid, and others are mainly based on caustic alkalis such as caustic soda, and the concentration range is generally 0.3 to 30%. Chemical etching may also be performed by adding salts such as silicates, vermichromates, nitrates, ammonium fluoride, ammonium phosphate, etc. to the acid/alkali. The bath temperature is preferably in the range of 10 to 90°C, and the treatment time is preferably in the range of 5 to 1000 seconds.

The average pitch of the fine concave structures formed by chemical etching is 1 to 10 microns, which is 14f7 lower than that of the concave structures formed by pressing. The 1 deJ degree of this fine coarse structure is 5.000 ~
200,000fi! , / m1ll' range is Qr
Preferably, it is formed overlying the concave structure formed by pressing.

The grain obtained by the present invention does not require the skill of brush polishing, compared to the grain obtained by the conventional method of brush til + polishing → chemical cleaning RF + → electrolytic etching.
In addition, it is a highly streamlined method that eliminates the need for the process of removing 1iIl@ agents and aluminum debris.
Can be built.

The grained aluminum can be used as it is as a support for planographic printing plates, but if necessary, it can be subjected to treatments such as anodization and chemical conversion treatment.

The anodic oxidation treatment can be carried out using a strip '1 conventionally employed in this field. Specifically, in an aqueous solution of sulfuric acid, phosphoric acid, chromic acid, sulfuric acid, sulfamic acid, benzenesulfonic acid, etc., or a combination of two or more of these, the electrolysis time is 15 seconds at a current density of 1 to 50 A/dI8. ~
It can be carried out for 15 minutes at a bath temperature of 25 to 75°C.

After anodizing, further hot water, silicate, dichromium rIli salt,
Hydrophilization treatment may be performed using an acetate, a hydrophilic polymer compound, or the like.

The photosensitive material applied to the aluminum grained plate of the present invention is not particularly limited, and various known materials can be used. For example, a negative-working photosensitive composition comprising a diazo resin and a binder, a positive-working photosensitive composition comprising an 0-quinonediazide compound and a binder,
Examples include a negative-working photosensitive composition comprising an azide compound and a binder, a negative-working photosensitive composition comprising a photodimerizable photopolymer, and a negative-working photosensitive composition comprising a photopolymerizable monomer and a binder. A photosensitive lithographic printing plate can be produced by dissolving these photosensitive compositions in a suitable solvent, applying the solution to the aluminum grained plate of the present invention, and drying it. If exposed and developed in layers, it has excellent hydrophilicity and water retention, and the adhesion between the photosensitive layer and the grains is strong, making it easier to see plate-made images (easier to see small dots) and easier to see when water rises. One gram of printing plate can be easily produced.

The present invention will be explained below based on Examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, in the example, an elliptical press concave? The density and the average length of the major and minor axes of 11 and the density and average pitch of the fine four parts by chemical tzing are determined by magnifying the aluminum surface to y + ooith with a scanning electron microscope, and measuring the oval pressed four parts within a certain area. Each was measured and calculated. In addition, the average line center roughness is based on JIS B 0601-19.
76's direction left J:・ノタ.

Example 1 Steel particles having a hardness (1-IV) of 860 and an average particle diameter of 250 μm were introduced into Griff 1 at an impeller rotation speed of 200 rpm, m250 ko/min, and shot 11. 'i
Between 23? )+7) Sprayed on a steel roll with ffi condition, passed through the roughened surface, first rolling reduction rate 7.6%,
Rolling treatment was performed at a rolling reduction rate of 6% in the second rolling, and 0.235
A roughened aluminum plate with a thickness of Inllll was obtained. The average roughness of the center line of the surface is 0.60μ, the average length of the long axis of the four parts of the oval press is 28μ, the average length of the short axis is 14μ,
The density of the oval press recesses is 2000/w+m'.

Subsequently, in an 8% Na01-1 aqueous solution, 60°C, 2.5
Chemical etching was carried out under conditions of 1.5 to 1.5 cm, and the average pitch was 1.
A fine concave structure with a diameter of 5μ and a density of 90,000 pieces/mm2 was provided. Next, 20 sheets were subjected to LHf! oxidation treatment in a 30% sulfuric acid bath at 30° C. and a current density of 6 A/dm'' to obtain grained plates.

An 0-quinonediazide photosensitive solution having the composition shown below was coated on this grained plate to a film thickness of 20 mg/den' to obtain a photosensitive printing plate.

naph i-quinone diazido 5-sulbonyl chloride and m
- Condensate with cresol/formaldehyde novolak 5.0+1 m-Cresol/formaldehyde novolac (manufactured by Sumitomo Durres) 9.0 g Victoria Pure Blue BOH (manufactured by fiA Tsuchiya Chemical Co., Ltd., trade name > 0.1 (1) Naphthoquinone diazide -4 -Sulbonyl chloride o,'
+9u Ethyl cellosolve 100 (+) Halftone dots 1?-1-, step tablets, and positive film were added to the thus obtained photosensitive printing plate and exposed with a metal halide lamp, followed by 4% sodium metasilicate.
When developed with an aqueous solution, 2% halftone dots were reproduced with 5-stage clear. Reflectance of non-image area (JIS D570
The method described in Section 5.9.1) was 1.0% and was excellent in terms of ease of viewing the printmaking image.

It was also excellent in terms of visibility on the water.

Example 2 NU (HV) 860, average particle size 500. cl)i141
The B particles were heated at an impeller rotation speed of 2500 rpm and a grid loading interval of 250 k (1/min, shot) to Shuma 3.
The mixture was sprayed onto a steel roll for 0 minutes to produce a rolling roll with a roughened surface. 115t aluminum plate with a thickness of 0.27 mm after hot rolling and cold rolling
0.0 (O1 Reisha Reisha) was passed through this roll and rolled at a reduction rate of 7.6% in the first rolling and 6% in the second rolling.
235111 roughened grain was obtained.

The center line roughness of the grain was 0.9μ, the average long-sleeve length of the oval press recesses was 55μ, the short axis average length was 35μ, and the density of the four oval press parts was 600 pieces/llll12.

A 400x scanning electron micrograph of the resulting grained surface is shown in FIG. It can be seen that a wavy pattern is formed on the surface of the support.

The obtained roughened plate was placed in a C15 aqueous solution of 10% NaOH.
Chemical etching was carried out at 0°C for 2 minutes with a stripe '1' to give a fine concave structure with an average pitch of 5.0μ and a density of 8,500 pieces/mm'. Furthermore, anodic oxidation treatment was performed for 20 seconds in a 1il1220% bath at a bath temperature of 25° C. and a current density of 6 A/da' to obtain a grained plate.

This grained board was subjected to a chemical conversion treatment for 11 minutes at 80'C with a 1% aqueous solution of sodium silicate, and then a diazo-based photosensitive liquid having the following composition was coated with a film of 17111 (1/dlll') to perform photosensitive printing. Got the edition.

11F6 salt (diazonium jn) of p-diazodiphenylamine/formaldehyde condensate 0,/112(1) Copolymer of p-hydroxyphenylmethacrylamide/acrylonitrile/ethyl acrylate/methacrylic acid
6.00 Victoria Pure Blue B Ol-1 <Hodogaya Chemical Co., Ltd., product name) 0.16g Polyacrylic li! l (Di1rin-AC- manufactured by Nikkokuseiyaku Co., Ltd.)
1OL (product name)) 0.18゜Methyl cellosolve 100g Halftone char 1~ on photosensitive printing plate, step tablet,
When the negative film was closely attached and exposed to light using a metal halide lamp, and the unbleached areas were removed using a developer having the composition shown below, halftone dots of -c2% were reproduced in 5 solid layers. The reflectance of the non-recorded area was 1%, which was excellent in terms of visibility of the printed image. In addition, a printing test was conducted in the same manner as in Example 1, and the printing test was also excellent in terms of visibility of the rising water.

Furthermore, tests were conducted to determine how easily the non-image area was stained and how easy it was to recover from the stain. That is, the number of prints (resistance to staining) until the water supply to the plate was stopped during printing and staining occurred was 8, which was good.

Next, apply ink to the entire surface of the non-image area (in a trough state) and supply water for 01 minutes. It turned out that it was a printing plate that was difficult to recover.

Example 3 Chemical etching was performed in a u/l aqueous solution at 60°C for 2 minutes, and the average pitch was 10μ, and the average 'fj degree was s, o.
oo pieces/n+m, F's four minute drawings were given. Next, 4#AM processing was performed in a 42% phosphoric acid bath at a current density of 3△/dm' and a bath temperature of 25°C at 5 minute intervals, and a photodimerization type photopolymer photosensitive solution having the following composition was heated to 14n+u/dm. A photosensitive printing plate was obtained by coating the film to a film thickness of .

1)-diethyl ester phenylene diacrylate and 1.
4-Dihythmyloxysilane 1 ~ Gycysic [polynisdel obtained by synthesis with cohekylene 4.0 2-benzoylmethylene-1-methyl-β-naphthodeazoline 0.3
2g Ammonium 13-phosphate o, 16-rehydroquinone 0.08u Phthalocyanine blue pigment 0. sg Monoku [100m1 of benzene per day, thus Hinoki! Silk 5 (, (
The chart, step tablet 1-, and negative film were placed in close contact with each other and exposed to light using a metal halide lamp, and the unexposed areas were removed using a developer having the following composition.

4-Butyrolactone 500ml 1~liethanolamine! :+Oml glycerin 5
Qml Methyl abietate 5ml Hydrogenated wood resin (Stabelite resin (trade name) manufactured by Percules Powder) 0.5 (1) Wetting agent (Zonyl A (trade name) manufactured by DuPont) 4.5ml Obtained print The plate reproduced a halftone dot of 1% in 5-stage peta.When it was attached to an offlet printing machine in the same manner as in Example 1 and a printing test was carried out, it was clear that the printing was easy to see.
100,000 good prints were obtained without any stains.

Comparative Example 1 While rotating a steel roll, the surface of the roll was polished with a grindstone, and a rolling roll having a linear pattern was obtained. A 0.27 mm aluminum temporary was passed through this rolling b-ru and rolled with a rolling reduction of 7.6% in the first rolling and a rolling reduction of 6% in the second rolling. The patterned grain is 1q. (Fig. 2) This grain was not subjected to chemical etching, phosphoric acid alumite treatment, photosensitive liquid coating, or exposure under the same conditions as in Example 3. This fact indicates that good halftone dot reproducibility can be obtained only when the press depressions R1i have a wavy pattern.

Comparative Example 2 Steel particles having a hardness (T IV) of 860 and an average grain size of 500 μm were heated at an impeller rotation speed of 1750 rl+m, a grid input f of 31250 ka/min, and a Schiff 1111 interval of 10
A rolling roll was manufactured by spraying the mixture onto a roll using a 9-minute strip.

Using this roll, rolling was carried out under the conditions of Comparative Examples 1 and 1-1, and the center line average roughness was 0.5μ, the long axis average length of the four oval press parts was 120μ, the width was 870μ on the width + average 1, and the density was 190. A piece of sand with a wavy pattern of 1/2 cm/mm2 was obtained. Chemical etching, phosphoric acid alumite treatment, photosensitive liquid coating, exposure, and development were performed on this grain using the same strips 1'1 as in Example 3. was about one step lower.

This fact indicates that the density of the wavy pattern is 200 pieces, /In1ll
'The following shows that the contact between the photosensitive layer and the grain (1) is insufficient.

[Brief explanation of drawings]

Figure 1 is an electron micrograph (400x magnification) of the surface of the aluminum plate roughened with a rolling roll, obtained in Example 2.
It is. Figure 2 is an electron micrograph (400 mm) of the surface of the aluminum plate obtained in Comparative Example 1 and roughened by grinding
times). FIG. 3 is an electron micrograph (400 mm) of the surface of an aluminum plate roughened by brush ω1 polishing. Applicant: Mitsubishi Chemical Industries, Ltd. Kumquat and 1 other attorney Patent attorney - For good or bad - 1 idiot No. I TFI
Bill θ7゜

Claims (3)

[Claims] (1) Forming four oval presses on the surface of an aluminum plate at a density of 200 pieces/mm' or more and so that some of the press recesses overlap to form a wavy pattern,
It is then chemically etched to create an average bit of 1.
A support for a lithographic printing plate formed with four fine parts of ~10μ. (2) Long axis average length of the oval press recess is 10 to 1.4
0μ, the short axis average length is in the range of 7 to 80μ, and the center line average roughness of the aluminum plate surface is 0.3 to 1.5μ.
The lithographic printing plate support according to claim 1, characterized in that the support is within the range of . (3) A support for a lithographic printing plate as claimed in claim 1, wherein the density of the fine recesses formed by chemical etching is from 5.0 to 200,000 pieces/mm2.