JPH07137474A - Production of support for planographic printing plate - Google Patents

Abstract

PURPOSE:To prevent a defective product based on a support surface state by grinding the surface of an aluminum support by using a brush composed of rigid bristles not substantially displaced even under specific compression load to form a rough surface having directionality and subsequently roughening the rough surface mechanically. CONSTITUTION:The surface of an aluminum plate subjected to the removal of rolling oil and surface washing is ground at first by a brush composed of rigid bristles not substantially displaced even when compression load of 3 kg is applied to form grain having directionality. In the grinding process using the brush, the protruding defect flaws on the surface of the aluminum plate are shaven off to make recessed defect flaws inconspicuous or to grind the aluminum plate uniformly in depth eliminating the recessed defect flaws and, succeedingly, the surface of the aluminum plate is set to roughness of a degree subjected to a mechanical surface roughening process. Thereafter, the surface of the aluminum plate is mechanically roughened to form a satin surface necessary for a printing plate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a lithographic printing plate support. More specifically, the present invention relates to a method for producing a lithographic printing plate support that allows a wide selection of a raw material made of aluminum or its alloy.

[0002]

2. Description of the Related Art Conventionally, aluminum or its alloy plate (hereinafter referred to as "aluminum original sheet") has been used as a support for a printing plate, particularly a lithographic printing plate. The support is a photosensitive layer provided thereon. It is necessary to have appropriate adhesiveness and water retention property. For this purpose, a roughening treatment, that is, a graining treatment is performed so that the surface of the support has a uniform and fine grain without directional property. As the surface roughening method, a wire grain (rolled wire of Japanese Patent Laid-Open No. 53-145701) made by rotating a roll-shaped metal wire or a nylon brush, and a blast grain made by colliding a brush grain or an abrasive with the surface (Japanese Laid-Open Patent Publication No. 50-136101, JP-A-60-19
No. 593, etc.), a mechanical surface roughening method, an electrochemical surface roughening method called electrolytic graining, a chemical surface roughening method, or a combination of these surface roughening methods ( JP-A-54-63902) has been proposed.

[0003]

However, among these conventional methods, even if the most precise and complete surface roughening is performed, it is not possible to prevent the generation of defective products due to a defective rough surface state. It has been found that the difficulty arises no matter how high-grade or expensive material is used. The inventors of the present invention have conducted extensive studies to overcome such difficulties, and as a result, no matter how high-grade an original fabric, a convex scratch such as a roll mark or a blister and a pickup, a concave scratch such as a surface crack, etc. It is impossible to completely avoid the scratches that occur during the manufacturing process and storage and transportation of the above, and further, it has been found that the above-described various conventional roughenings are not sufficient to overcome all of these scratches, and the present invention has been reached. did.

An object of the present invention is to prevent defective products due to the surface condition of the support, which has been inevitably generated in the past, and another object of the present invention is that it cannot be solved by ordinary surface roughening. Another object of the present invention is to provide a method for producing a lithographic printing plate that enables the use of a low-cost and low-cost substrate material having various scratches. It is an object of the present invention to provide a method for producing a lithographic printing plate, which substantially completely avoids the generation of defective products even when using a raw sheet having uncontrollable scratches and enables a significantly high product yield.

Therefore, the object of the present invention is to grind the surface of an aluminum support with a brush made of rigid brush bristles that do not substantially displace even when a compressive load of 3 kg is applied, to form a rough surface having directionality. After the formation, mechanical roughening is carried out to form a rough surface having no directionality, which is easily achieved by a method for producing a lithographic printing plate support.

The present invention will be described in detail below. Pure aluminum and aluminum alloy plates are included as the aluminum original fabric applied to the present invention. Various types of aluminum alloy plates can be used, such as silicon,
Alloys of aluminum with metals such as copper, manganese, magnesium, chromium, zinc, lead, bismuth, and nickel are used.

The aluminum raw material used in the present invention is
It may have a defect scratch larger than the roughness of the grain, which is generated during rolling of the raw fabric and is necessary for a printing plate formed later. More specifically, larger than the roughness of the sand formed later, convex marks such as roll marks and blisters,
The height of the recess may be, for example, a pickup or a surface crack, but the height is approximately 5 μm or more and 10 μm or less, preferably 50 μm.
m or less, width of 10 μm or more, length of 10 μm or more, and / or depth of 5 μm or more and 50 μm or less,
Preferably 30 μm or less, width 10 μm or more, length 1
It means a concave scratch of 0 μm or more. A large number of defect scratches may be present on the aluminum original fabric.

When the size of the defect scratches is less than the above range, even if it is present even in the conventional graining process, there is little influence and it may not hinder the use as a lithographic printing plate. On the other hand, a raw material having scratches exceeding the above range is extremely rare as a normal product, but if such a large flaw scratch exists, it is desirable to avoid using it. For example, with respect to the height of the convex scratches, a stock having a flaw scratch exceeding 100 μm makes a dent on the back side of the aluminum stock during winding, and a printing plate having such a back scratch is a defective product. , Often not used from a practical point of view. Further, regarding the concave scratch, since it is necessary to remove aluminum by the depth of the scratch, if the scratch is too deep, uneven plate thickness may occur.

Although the rolling oil or scale attached to the surface of the aluminum raw material may be left as it is, the rolling oil may be removed and the surface may be washed prior to the treatment of the present invention. Specifically, for example, a solvent such as trichlene, a surfactant, and an alkali such as sodium hydroxide or potassium hydroxide.
Examples thereof include a method using an etching agent. When degreasing with alkali, smut is generated on the surface,
Subsequently, it is preferable to perform immersion treatment in nitric acid, sulfuric acid or the like.

In the present invention, for example, the surface of an aluminum plate prepared in this way is first ground by using a brush made of rigid brush bristles that does not substantially displace even when a compressive load of 3 kg is applied, and the grain has directional properties. To form. The step of grinding with the brush is carried out by scraping off the convex defect scratches on the surface of the aluminum original fabric and making the concave defect scratches inconspicuous, or by uniformly grinding to a depth such that it disappears. It is possible to make the surface rough enough to be used in the mechanical surface roughening process. It is general that the grinding direction of the brush remains on the surface of the aluminum plate that has been subjected to the grinding process to form a directional grain.

The brush used in the present invention has a structure in which the bristles of the brush are made to have rigidity so that they are not substantially displaced even when pressed against an aluminum original fabric. More specifically, the brush used in the present invention may have one brush bristle or may be aggregated and solidified, but a brush having a bristle length of 30 mm is compressed by 3 kg in the length direction. It has rigidity that does not substantially displace when a load is applied.

The brush used in the present invention is not particularly limited as long as it has the above-mentioned rigidity. For example, a fine wire obtained by kneading an abrasive in a resin having a diameter of about 0.03 to 1 mm is used as the brush bristles. As a diameter of several hundred to several thousand
Roll brush with a structure in which solidified 10 mm rods are densely arranged on the side surface of a cylindrical pedestal, or thin wires such as stainless steel or brass with a diameter of 0.03 to 1 mm which is stronger than aluminum. Can be preferably used as a bristle of a brush, and a plurality of hundreds to several thousands of them are aggregated and solidified into a rod shape having a diameter of 3 to 10 mm and are densely arranged on a hollow disk type pedestal.

Therefore, in the present invention, the resistance to compressive load of the bristles means the value of the single wire when it is used as a single wire, and the value in the bundled state when the thin hairs are bound or collectively solidified. . The resin used for the roll brush is not particularly limited, but for example, polyamides such as nylon known as general-purpose plastics and engineered plastics, polyolefins such as polypropylene, polyvinyl chloride, polyesters such as polybutylene terephthalate, and polycarbonates. Can be raised.

The abrasive to be kneaded into the roll brush is not particularly limited as long as it is a commonly used abrasive, and examples thereof include alumina, silica, silicon carbide and silicon nitride. Although the optimum range of the particle size of the abrasive varies depending on the desired roughness, for example, an abrasive in the range of JIS standards # 240 to # 1500 can be preferably used.

Grinding with the brush of the present invention is performed by pressing the brush against the surface of the aluminum plate while rotating the brush at a high speed. Since the pressure value applied to the brush varies depending on the rigidity of the aluminum plate and the roll brush, it is preferable to control it by the reduction amount of the roll brush, and the reduction amount is 0.5.
Generally, it is appropriately adjusted to be in the range of about 5 mm.

In the brush grinding of the present invention, water or the like may be sprayed for the purpose of cooling the apparatus and the aluminum plate or cleaning the abrasive. The size and the number of brushes are appropriately adjusted and used according to the height and depth of the defective scratches on the aluminum plate. Following grinding with a brush, the surface of the aluminum plate is mechanically roughened to form a uniform matte surface required for a printing plate.

The mechanical surface roughening method in the present invention is not particularly limited as long as it is a conventional mechanical surface roughening method, and for example, a roll-shaped metal wire or a wire made by rotating a nylon brush is used. Grain (Japanese Unexamined Patent Publication No. 53-145701), blast grain (Blade Japanese Unexamined Patent Publication No. Sho 50-136101, Japanese Unexamined Patent Publication No. Sho 60-19593, Japanese Patent Application No. 4-). No. 313645) and the like.

As the conventionally known roughening method, a chemical roughening method and an electrochemical roughening method are known in addition to the mechanical roughening method. The combination of the electrochemical graining method with the brush grinding of the present invention may not be sufficient to remove the defective scratches. After the mechanical roughening, chemical roughening and / or electrochemical roughening may be further performed if necessary.

The chemical surface-roughening treatment has an effect of removing the abrasive or the like remaining on the surface formed by the surface-roughening treatment.
As a method of chemically treating, a known method such as a method of immersing in an acid that dissolves aluminum or an aqueous alkali solution can be applied. In this treatment, it is particularly preferable to use an alkaline aqueous solution. This is because alkali has a higher dissolution rate of aluminum and is more efficient than acid. Further, since smut is generated when treated with an alkaline aqueous solution, it is preferable to subsequently perform a dipping treatment in nitric acid, sulfuric acid or the like.

The chemically treated aluminum plate may then optionally be surface electrochemically treated.
A conventionally known method can be used for the electrochemical surface roughening. Further, it is preferable to perform a chemical treatment after the electrochemical graining treatment. The purpose is to remove smut and the like remaining on the surface formed by the electrochemical graining treatment. As the method of chemically treating, there is a method of immersing in an acid that dissolves aluminum or an alkaline aqueous solution, and the same as the case of the chemical treatment after the mechanical surface roughening treatment described above. You can Further, when treated with alkali, smut is also generated due to this, so that it is preferable to subsequently perform a dipping treatment in nitric acid, sulfuric acid or the like.

The aluminum plate treated as described above is further subjected to an anodic oxidation treatment by electrolytic treatment in an aqueous solution of sulfuric acid, phosphoric acid or the like according to a conventional method, and thereafter, if necessary, heat treatment for hydrophilization or inactivation. Water treatment, silicates, acetates,
Immersion treatment or the like in an aqueous solution containing a hydrophilic polymer compound can be performed. A photosensitive lithographic printing plate can be obtained by providing a photosensitive layer on the aluminum plate or its alloy plate thus obtained according to a conventional method.

The photosensitive material of the photosensitive layer applied to the lithographic printing plate of the present invention is not particularly limited, and generally known materials can be applied. For example, a composition comprising a hydrophilic polymer and a diazonium salt, a composition comprising a quinonediazide compound and an alkali-soluble resin, an unsaturated carboxylic acid that dimerizes upon irradiation with actinic rays, such as cinnamic acid, phenylenediacrylic acid as its constituent components. The polymer, a composition of a compound that causes a polymerization reaction upon irradiation with actinic rays and a binder polymer, or an azide-based photosensitive composition can be preferably used.

[0023]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples as long as the gist thereof is not exceeded.

Example 1 Height about 12 μm, Width about 50 μm
m, length about 0.5-5 mm, convex scratches about 5-10 pieces / m
^{About 2} , material 1050, temper H16, thickness 0.3mm
A coil-shaped aluminum original fabric having a width of 1000 mm was used, the aluminum original fabric coil was attached to the unwinding coil side, and the following treatments were performed up to the winding coil.
The tension of the aluminum raw fabric was 3 kg / mm ² , and the conveying speed was 6 m / min. (1) Degreasing treatment Soaking in an aqueous solution of sodium hydroxide was performed for degreasing, followed by washing with water, dipping in an aqueous solution of sulfuric acid, and finally washing with water.

(2) Roll brush scrub An iron roll having an outer diameter of 300 mm and a width of 1300 mm is assembled with fine wires having a wire diameter of 0.5 mm obtained by kneading Al ₂ O ₃ of JIS standard # 320 into nylon resin. It was solidified into a rod shape having a diameter of 5 mm, which was uniformly planted on a donut-shaped brush pedestal so that the length of the brush bristles was 30 mm to prepare a roll brush. Next, the aluminum raw fabric was passed between the roll brush and the backup roll while spraying water. At that time, the roll brush was rotated at 500 rpm and pressed against the surface of the aluminum original fabric so that the amount of reduction was 2 mm. When the surface was observed after the roll brush scrub, the marks of the roll brush were seen, but the convex scratches seen before the brush scrub were not observed. The JIS standard surface roughness of the aluminum plate is Ra 0.45 μm, Rmax
Was 5.8 μm.

(3) Mechanical Roughening First, it was washed with water and then grained by the liquid graining method shown below. Al ₂ O ₃ abrasive with particle size JIS # 150 is mixed in water so that the volume ratio is 20 parts, and is evenly dispersed by a stirrer, and 72 nozzles having an elliptical shape with a vertical diameter of 2 mm and a horizontal diameter of 4 mm. The aluminum raw fabric surface was mechanically roughened by spraying at a pressure of 4 kg / cm ² .
As a result, a uniform pear-like grain having no scratch was obtained by surface observation. At that time, the JIS standard surface roughness is R
a was 0.60 μm and Rmax was 7.5 μm.

Example 2 The same process as in Example 1 was carried out except that the mechanical surface roughening was carried out as follows. An iron roll with an outer diameter of 300 mm and a width of 1300 mm is coated with nylon resin with a wire diameter of 0.3 μm as the length of the brush bristles.
Install two roll brushes that are evenly bristled to 0 mm in parallel and rotate at 300 rpm, and the particle size is JIS
While spraying a slurry in which # 220 Al ₂ O ₃ abrasive was mixed homogeneously with water to a volume ratio of 20 parts, the surface was mechanically roughened by pressing it against the aluminum raw surface so that the reduction amount was 5 mm. I went. As a result, a uniform pear-like grain having no scratch was obtained by surface observation. Also, JI at that time
As for the surface roughness of S standard, Ra was 0.55 μm and Rmax was 7.0 μm.

Example 3 Depth of about 15 μm, Width of about 100
Approximately 4 to 6 convex scratches of μm and length of about 150 μm / m ² , material 1050, temper H16, thickness 0.3 mm width 1
Using a coiled aluminum original fabric of 000mm, the aluminum original fabric coil is unwound and attached to the coil side,
Each treatment was performed up to the winding coil. The following treatments were performed. In addition, the tension of the aluminum original fabric at that time is 3 kg /
mm ² , and the transportation speed was 6 m / min.

(1) Degreasing treatment The same conditions as in Example 1 were used. (2) Scratch removal An iron roll having an outer diameter of 300 mm and a width of 1300 mm was kneaded into a nylon resin with Al ₂ O ₃ having a particle size of JIS standard # 320, and fine wires having a wire diameter of 0.5 mm were collected and solidified.
Make rods with a diameter of 5 mm and use them as brush bristle lengths 3
Arrange two roll brushes that are evenly bristled to 0 mm, rotate them at a speed of 500 rpm, and spray them with water while pressing them against the surface of the aluminum roll so that the reduction amount is 3 mm. Grinding was performed between the backup roll and the backup roll. In the subsequent surface observation,
Although the marks of the brush were visible, the convex scratches that had been seen before scratching were not recognized. The JIS standard surface roughness at that time was Ra of 0.50 μm and Rmax of 6.3 μm.

(3) Graining It was carried out under the same conditions as in Example 1. As a result, in the subsequent surface observation, uniform pear-like grain without any scar was obtained. In addition, the Ra of the JIS standard surface roughness at that time is 0.60 μm.
m and Rmax were 7.2 μm.

Comparative Example 1 Using the same aluminum raw material as in Example 1, the same degreasing treatment as in Example 1 was performed, and then the same graining treatment as in Example 1 was performed. As a result, in the subsequent surface observation, the height was about 8 μm, the width was about 50 μm, and the length was about 0.
About 5 to 10 convex scratches of 5 to 5 mm were recognized per 1 m ² .

[Comparative Example 2] The same aluminum raw material as in Example 1 was used, the same degreasing treatment, scratching and washing with water as in Example 1 were performed, and then 1.6% nitric acid aqueous solution was used at 27 ° C. Using a sinusoidal alternating current with a voltage of 20 V, electricity of 1000 A
50 sec / dm ² electrochemical graining
Desmutting treatment was performed for 5 seconds in a 1% sodium hydroxide aqueous solution at 0 ° C. As a result, after the surface was observed, a satin finish was obtained, but brush marks remained during the scratch removal process.

[0033]

According to the method for producing a support for a lithographic printing plate of the present invention, it becomes possible to prevent defective products due to the surface condition of the support, which has been inevitably generated in the past, and it is possible to prevent an ordinary rough surface. It is possible to use low-grade and inexpensive raw fabrics that have scratches that cannot be resolved by aging, and it is possible to use defective raw fabrics not only with scratches that exist steadily but also with unmanageable scratches that occur accidentally. It is possible to avoid generation almost completely and to achieve a significantly high product yield.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Katayama 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Sanryo Kasei Co., Ltd. (72) Inventor Hideyuki Nakai 1 Sakura-cho, Hino, Tokyo Konica Stock Company (72) Inventor Shinichi Matsubara 1 Sakura-cho, Hino City, Tokyo Konica Stock Company

Claims (1)

[Claims] 1. An aluminum support surface is ground using a brush made of rigid brush bristles that are not substantially displaced even when a compressive load of 3 kg is applied to form a directional rough surface. A method for producing a support for a lithographic printing plate, which comprises performing a roughening process to form a rough surface having no directionality.