JPH05229275A - Production of aluminum support for planographic printing plate - Google Patents

Abstract

PURPOSE:To produce an aluminum support for a planographic printing plate having a surface excellent in water retentivity, improved in the close adhesiveness with the photosensitive layer provided on aluminum and excellent in printing durability. CONSTITUTION:An aluminum plate is mechanically ground and subsequently subjected to alkali etching. This aluminum plate is subjected to AC electrolytic grinding in an electrolyte containing 30-100g/l of hydrochloric acid, 2.0-30g/l of boric acid, 15-50g/l of an aluminum ion and 0.1-20g/l of silicon dioxide and further subjected to alkali etching to produce an aluminum support for a planographic printing plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum support for a lithographic printing plate, and more specifically, it has a surface excellent in water retention and has good adhesion to a photosensitive layer provided on the support. And a method for producing an aluminum support for a lithographic printing plate having excellent printing durability.

[0002]

2. Description of the Related Art Conventionally, an aluminum plate has been widely used as a support for a lithographic printing plate. In this aluminum plate, in order to improve the adhesion to the photosensitive layer and to impart water retention to the non-image area. Then, the surface is polished (etching,
Also called graining or roughening. ) Is generally done.

As a method for polishing an aluminum plate,
There are mechanical polishing methods such as ball polishing and brush polishing, electrolytic polishing methods using hydrochloric acid or nitric acid or an electrolytic solution mainly containing these, chemical etching by chemicals, dry or wet honing processing methods, and more. It is known that the method. Among these, the electropolishing method has attracted attention in recent years, and most of them perform electrolytic treatment by alternating current in an electrolytic solution containing hydrochloric acid or nitric acid as a main component.

In the electropolishing method, the shape and surface roughness of the grains formed by electrolysis can be adjusted by changing the electrolysis conditions such as the composition of the electrolyte and the amount of electricity. In the case of electrolytic polishing, unlike mechanical polishing, it is possible to form pits (holes) on the aluminum surface, and the size and depth of these pits can be formed in various shapes. It is well known that the size and depth of the pits and the distribution of the pits greatly affect the properties (water retention, printing durability, etc.) of the lithographic printing plate support.

When hydrochloric acid is used as the electrolytic solution, pits due to electrolysis are non-uniformly scattered on the aluminum surface, and as the electrolysis progresses, only the first electrolyzed part is etched deep, large and insect-like. , The other parts are not etched. Therefore, it cannot be said that the printing plate is very good in terms of water retention and adhesion of the photosensitive layer (printing durability). Further, when an electrolytic solution containing nitric acid as a main component was used, relatively fine pits were formed, but deep etching could not be performed, resulting in poor water retention and adhesion.

In order to solve these drawbacks, a method of incorporating tartaric acid in an electrolytic solution containing hydrochloric acid (Japanese Patent Laid-Open No. 53-700).
53), a method of adding an alkali metal halide (JP-A-55-17580), a method of adding citric acid or malic acid (JP-A-56-1335095),
Method of Incorporating β-Dicarbonyl Compound (JP-A-57 / 1982)
No. 24294), a method of adding a phenol compound (JP-A-57-24295), a method of adding an ionic halogen compound (JP-A-60-159093), and a method of adding an organic carboxylic acid (JP-A No. 60-23489
No. 5), condensed phosphoric acid, amidosulfonic acid, and a compound selected from the group consisting of water-soluble alkali metal salts or ammonium salts (JP-A-60-2348).
96), a diphosphonic acid, a polyphosphonic acid, and a compound selected from the group consisting of gallic acid (JP-A-60-234897), and a method of incorporating at least one compound containing an ammonium ion (special (Kaisho 61-182949) and the like have been proposed, but they are not always sufficiently satisfactory in water retention and printing durability.

[0007]

DISCLOSURE OF THE INVENTION In view of the above-mentioned problems, the inventors of the present invention first electropolished a mechanically polished aluminum plate using an electrolytic solution containing hydrochloric acid, boric acid and aluminum ions. Method (JP-A-3-1203)
No. 99) was proposed. However, the inventors of the present invention were not satisfied with this, and have conducted further diligent studies and completed the present invention for the purpose of obtaining a grain having further excellent water retention and printing durability. ..

[0008]

According to the present invention, an aluminum plate is mechanically polished and then hydrochloric acid is added in an amount of 30 to 100 g /
1, boric acid 2.0 to 30 g / l, aluminum ion 1
A method for producing an aluminum support for a lithographic printing plate, characterized by performing electrolytic polishing by alternating current in an electrolytic solution containing 5 to 50 g / l and 0.1 to 20 g / l of silicon dioxide, and an aluminum plate mechanically After polishing to alkaline, it is subjected to alkali etching, and then hydrochloric acid 30 to 100 g / l, boric acid 2.0 to 30 g / l, aluminum ions 15 to 50
Disclosed is a method for producing an aluminum support for a lithographic printing plate, which comprises performing electrolytic polishing by alternating current in an electrolytic solution containing g / l and 0.1 to 20 g / l of silicon dioxide, and further performing alkali etching. is there.

The aluminum plate includes both a plate made of pure aluminum and a plate made of aluminum alloy. In the method of the present invention, first, the rolling oil on the surface of the aluminum plate is removed, and in order to expose the clean aluminum surface, the surface of the aluminum plate is preferably pretreated. Examples of the pretreatment method include cleaning with a solvent or a surfactant or etching cleaning with an alkaline agent.

In the method of the present invention, mechanical polishing is performed subsequent to the above pretreatment. This mechanical polishing method is not particularly limited, but considering the case of continuously polishing a coiled aluminum plate, the brush polishing method is preferable. Mechanical polishing has a center line average roughness (Ra) of 0.3.
It is preferable to carry out so that the thickness is about 0.6 μm.

After performing such mechanical polishing,
The surface of the aluminum plate is preferably chemically alkali-etched for the purpose of removing the abrasive and removing the aluminum dust. Examples of the alkaline agent used at this time include sodium hydroxide, potassium hydroxide, sodium triphosphate, potassium triphosphate, sodium aluminate, sodium carbonate, sodium metasilicate, sodium orthosilicate, etc. A mixture of two or more kinds can be used.

The alkali concentration of the above alkaline solution is 1 to 6
0% by weight is preferable, and the aluminum plate is 30 to 100 ° C.
At a liquid temperature of 2 to 60 seconds, 0.5 to 10 g /
m ² Etch. As a method of etching, there are a method of immersing an aluminum plate in an etching bath, a method of spraying an alkaline solution with a spray or a nozzle, and a method of flowing a solution through a slit-shaped mouth to perform etching.

After performing the above-mentioned alkali etching,
Desmutting is preferably carried out with nitric acid, phosphoric acid, sulfuric acid or chromic acid or a mixed acid containing two or more of these acids,
Or just rinsing with water, and in some cases high pressure rinsing (3k
g / cm ² or more) to remove smut.

Following these treatments, electrolytic polishing treatment is performed. The electrolytic solution used in the present invention is hydrochloric acid (using 35% by weight of hydrogen chloride) 30 to 100 g /.
1, preferably 35 to 80 g / l, boric acid 2.0 to 30
g / l, preferably 4.0 to 25 g / l, aluminum ions 15 to 50 g / l, preferably 20 to 40 g / l
1 and 0.1 to 20 g / l of silicon dioxide, preferably 0.5 to 15 g / l.

The concentration of hydrochloric acid in the electrolytic solution is 100 g
If it is / l or more, deep and large pits are more likely to be generated unevenly, and if it is 30 g / l or less, it becomes difficult for electricity to pass, and the electrolysis voltage must be set high, resulting in high power consumption. This will increase the cost. When the concentration of boric acid is 30 g / l or more, the polishing ability is obstructed to form shallow pits, and when it is 2.0 g / l or less, fine pits cannot be formed, the addition effect is not exhibited, and no addition is made. It will be the same as in.

The boric acid used in the present invention includes
Also included are borate salts. Examples of the borate include ammonium borate, sodium borate, potassium borate, lithium borate, barium borate, lead borate, aluminum borate, and methyl borate.

The aluminum ion concentration is 50 g /
When it is 1 or more, deep and large insect-like pits are likely to be unevenly formed. When such an aluminum plate is used as a printing plate support, the ink and the residue of the photosensitive film are likely to remain in the deep and large insect-like pits, which causes stains. Further, in order to reduce the amount to 15 g / l or less, the eluted aluminum ions must be constantly removed, and when discarded as a waste liquid, it becomes an environmental problem, and the hydrochloric acid content contained in the waste liquid is also increased. Must be replenished, which eventually leads to an increase in running cost. Therefore, the above range of 15 to 50 g / l is a range suitable for the purpose of the present invention from many experiments.

The inventors of the present invention observed the pit diameter formed on the grain of the aluminum plate electrolytically polished using the above-mentioned electrolytic solution containing hydrochloric acid, boric acid and aluminum ions by an electron microscope and found that the pit diameter was uniform. However, most of them had a pit diameter of 0.5 μm or less. However, when electrolytic polishing is carried out by adding 0.1 to 20 g / l, preferably 0.5 to 15 g / l of silicon dioxide to the electrolytic solution, the pit diameter becomes 1 to 2 μm, and the photosensitive material having the grain is formed. When the performance of the lithographic printing plate was evaluated, it was found that the non-image did not easily stain and had excellent printing durability. That is, the present inventors have found that by adding a specific amount of silicon dioxide to the electrolytic solution, it is possible to obtain a lithographic printing plate excellent in printing durability of the image area and stain resistance of the non-image area. If the concentration of silicon dioxide is 0.1 g / l or less, the effect of addition is not exerted, and if it is 20 g / l or more, many pit diameters of 2 μm or more are generated, and the ink is apt to be clogged in that portion, resulting in contamination. Is difficult to remove. In addition, the electrolysis voltage is increased by about 30% or more, the amount of electric power used is large, and the cost is not good.

The above-mentioned silicon dioxide can be obtained in the form of silica fine powder, fine particulate anhydrous silica, or colloidal silica (an ultrafine colloidal solution of silicic acid anhydride). Use by floating. When silica-based silica stone powder is used as an abrasive during the mechanical polishing, the abrasive may adhere to the aluminum surface and enter the electrolytic cell. It is necessary to adjust to fall within the range of the present invention (0.1 to 20 g / l). When the amount of silicon dioxide becomes 20 g / l or more, the electrolytic solution is filtered to remove the silicon dioxide, or a part or all of the electrolytic solution is replaced with a new solution.

Electricity used for electrolytic treatment is single-phase alternating current or three-phase alternating current, preferably 10 Hz to 200 H.
A sine wave in the z range, a waveform obtained by cutting a part of alternating current by a thyristor, or an alternating wave having a (+) (-) ratio of 30% or less is used. The voltage applied to the aluminum plate is about 1 to 50 as a result of many experiments conducted by the inventors of the present invention from the viewpoint of the shape of the grain and the economical viewpoint.
V, more preferably 5 to 35 V, with a current density of about 5 to 5
It is 0 A / dm ² , more preferably 10 to 40 A / dm ² , and the electric quantity is about 50 to 3000 coulombs, more preferably 100 to 2000 coulombs.

The temperature of the electrolytic solution is about 10 to 60 ° C., more preferably 20 to 50 ° C., and the distance between the electrode and the aluminum plate is 1 to 10 cm, more preferably 2 to 5 cm. Since the aluminum plate roughened by mechanical polishing and electrolytic polishing as described above is soft and easily worn as it is, anodizing treatment is performed to form an oxide film on which a photosensitive layer is provided. .. The surface of the aluminum plate thus treated is hard and has excellent abrasion resistance, and exhibits good hydrophilicity, water retention and adhesion to the photosensitive layer.

However, since smut adheres to the surface subjected to the roughening treatment, if the anodic oxidation treatment is immediately carried out, the anodic oxide coating becomes black and not only the appearance value is remarkably impaired, but also the coating thereon. The sensitivity of the photosensitive layer is lowered, or variations occur, and the plate inspection property is deteriorated even after development. Further, since a layer having poor adhesion is formed on the surface, printing durability is also reduced. In order to improve such a defect, it is preferable to carry out washing with water after electrolytic polishing and alkali etching to remove smut and smut inside the pit at the same time, thereby making the color of the aluminum surface white. As the alkaline agent used at this time, one having substantially the same composition as the alkaline etching solution used after the mechanical polishing can be used.

The anodizing treatment can be carried out according to a conventionally known method. For example, a method is used in which sulfuric acid, phosphoric acid, chromic acid, oxalic acid, or an aqueous solution in which two or more of these are combined is used as an electrolytic solution, and a direct current or an alternating current is applied to aluminum to form an anodized film on the surface of an aluminum plate. be able to.

The aluminum plate anodized as described above may be further subjected to silicate treatment with sodium silicate, potassium silicate or the like, if necessary, or undercoated with hydrophilic cellulose or polyvinylphosphonic acid. Layers can also be provided.

A lithographic printing plate or a photosensitive lithographic printing plate (PS plate) is prepared by providing a conventionally known photosensitive layer on the aluminum support for a lithographic printing plate of the present invention thus obtained. be able to. For example, it can be used as an aluminum planographic printing plate made of polyvinyl alcohol and dichromates or a water-soluble diazo resin, an amyl egg white plate, and an aluminum wipe-on plate made of a water-soluble diazo resin and lacquer.

As the photosensitive layer for the photosensitive lithographic printing plate (PS plate), for example, a photosensitive layer containing a solvent-soluble diazo resin and a water-insoluble and lipophilic polymer compound having a hydroxyl group, O
A photosensitive layer comprising a mixture of naphthoquinone diazide sulfonic acid ester and a novolac type phenol or a cresol resin, a photosensitive layer containing an alkali-soluble polymer compound, an addition polymerizable unsaturated compound and a photopolymerization initiator,
A photosensitive layer made of an azide photosensitive material and a novolac type phenol resin can be used. It can also be used as a support for a lithographic printing plate for electrophotography using a zinc oxide material or an organic photoconductor as a photosensitive material.

[0027]

[Working] When the surface of an aluminum support for a lithographic printing plate obtained by the method of the present invention is coated with the above-mentioned photosensitive layer, it is excellent in storage stability and is particularly stable under severe conditions such as high temperature and high humidity. A photosensitive lithographic printing plate having performance can be obtained. Further, the printing plate thus formed has excellent image inspection property, and the aluminum surface of the non-image area is hard to be contaminated with the printing ink, and further has good hydrophilicity for quickly removing the contaminated ink. In addition, excellent printing durability can be obtained due to the high adhesion to the photosensitive layer.

[0028]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples unless the gist thereof is exceeded. In the following examples,% means% by weight unless otherwise specified.

Examples 1 and 2: Comparative Examples 1 and 2 A 0.24 mm thick aluminum plate (material 1050) was immersed in a 5% aqueous sodium hydroxide solution at 50 ° C. for 10 seconds to degrease it, and then a silica stone. The surface was polished with a nylon brush while applying an aqueous suspension of powder, and then thoroughly washed with water. Next, add 5% of 20% sodium hydroxide solution at 70 ° C.
After flowing for 2 seconds, the surface was etched, washed with running water, and using the electrolytic solution shown in Table 1, a three-phase alternating current, a current density of 30 A / dm ² , and an electric quantity of 250 coulomb / dm ²
Was electrolytically polished so that Then, after washing with water, the surface is etched by pouring caustic soda solution of 20% at 70 ° C., further washing with water, and then anodizing treatment in a 10% sulfuric acid aqueous solution at 30 ° C.
An oxide film of g / m ² was formed.

[0030]

[Table 1]

A photosensitive solution having the following composition was coated on the thus obtained support and dried to form a photosensitive layer. The dry weight of the photosensitive layer was 2.0 g / m ² . Note Ester compound of naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and acetone / pyrogallol resin 2.6 g Cresol novolac resin 6.0 g 2- (4'-methoxy-1'-naphthyl) -2, 6-bis (trichloromethyl) -S-triazine 0.06 g oil blue 613 (manufactured by Orient Chemical Industry Co., Ltd.) 0.15 g ethylene glycol monomethyl ether 50 g propylene glycol monomethyl ether 50 g

The photosensitive lithographic printing plate thus prepared was exposed under a positive film with a high pressure mercury lamp of 3 KW from a distance of 1 m for 45 seconds. Next, 2 having the following composition
An image was formed by immersing in a developer at 5 ° C for 20 seconds. JIS No. 3 sodium silicate 25g potassium hydroxide 15g anionic surfactant 1g water 1Kg

After washing with water and desensitizing with gum arabic solution, each printing plate was placed on a printing machine, the ink roller was dropped without giving water to the plate surface, and the ink was made to adhere to the entire image area and non-image area. It was After that, drop the water rod, and remove the ink in the non-image area completely, and raise the water rod in a state where it is printed normally, and vice versa. The number of sheets until the ink started to adhere to the non-image area without giving water and the printed matter began to stain (the number of stains) was examined. It can be said that the smaller the number of lost sheets is, the better the number is, and the larger the number is, the better the plate is. The printing durability of the image area was also examined at the same time. The results are shown in Table 2.

[0034]

[Table 2]

As is clear from the results shown in Table 2, the printing plates obtained in Examples 1 and 2 had the same content as Comparative Example 1 using the electrolytic solution containing no silicon dioxide and the content of silicon dioxide was the same. Comparative Example 2 using more electrolyte than the scope of the invention
It is a plate that is superior in water retention and printing durability to the printing plate obtained in.

Examples 3 and 4: Comparative Examples 3 and 4 The aluminum plates obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were placed in a JIS No. 3 sodium silicate 5% solution at 70 ° C. for 10 seconds. After processing and washing with water, the following composition liquid was applied to prepare a negative photosensitive lithographic printing plate having a photosensitive layer having a dry weight of 1.8 g / m ² .

2. Copolymer of 2-hydroxy-3-phenoxypropyl alcohol / methyl methacrylate / acrylonitrile / mono (2-methacryloxyethyl) hexahydrophthalate = 40/30/10/20 weight ratio 3. 0 g 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate of a condensate of 4-diazodiphenylamine and formaldehyde 0.3 g Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.) 0.1 g Malic acid 0.03 g Ethylene glycol monomethyl ether 90 g N-N'-dimethylformamide 10 g

The negative type photosensitive printing plate was exposed under a negative film using a 3 KW high pressure mercury lamp for 30 seconds from a distance of 1 m. Next, an image was formed by immersing for 20 seconds in a developing solution having the following composition at 25 ° C. Note potassium silicate 20% aqueous solution 50 g phenyl glycol PGH (manufactured by Nippon Emulsifier Co., Ltd.) 40 g isopropyl potassium naphthalene disulfonate 5 g potassium sulfite 2 g water 903 g

After washing with water and desensitizing with a gum arabic solution, each printing plate was placed on a printing machine, and the number of damaged sheets and the number of stains were examined. The printing durability of the image area was also examined at the same time. The results are shown in Table 3.

[0040]

[Table 3]

As is clear from the results shown in Table 3, the printing plates obtained in Examples 3 and 4 are superior in water retention and printing durability to the printing plates obtained in Comparative Examples 3 and 4. It is a version.

[0042]

The lithographic printing plate using the aluminum support obtained by the present invention is excellent in water retention, printing durability and stain resistance of non-image area.

Claims (2)

[Claims] 1. An aluminum plate is mechanically polished and then hydrochloric acid 30 to 100 g / l and boric acid 2.0 to 30 g / l.
1. A method for producing an aluminum support for a lithographic printing plate, which comprises electrolytically polishing by alternating current in an electrolytic solution containing 1, 50 to 50 g / l of aluminum ions and 0.1 to 20 g / l of silicon dioxide. 2. An aluminum plate is mechanically polished, alkali-etched and then hydrochloric acid 30 to 100 g
/ L, boric acid 2.0 to 30 g / l, aluminum ions 15 to 50 g / l and silicon dioxide 0.1 to 20 g / l
2. The method for producing an aluminum support for a lithographic printing plate according to claim 1, wherein electrolytic polishing is performed by alternating current in an electrolytic solution containing, and further alkaline etching is performed.