JPH0714671B2 - Method for producing lithographic printing plate support - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a lithographic printing plate support.

[Conventional technology]

There are various methods for producing a lithographic printing plate support, but in the electrochemical treatment method and the chemical treatment method, the reaction state can be controlled by changing the reaction time, liquid composition, liquid temperature, electrical conditions, etc. It controls the reaction.

However, in recent years, there has been an increasing demand for improvement in productivity, and it has been necessary to shorten the processing time. Therefore, the solution temperature has been raised or the processing tank has been extended.

[Problems to be solved by the invention]

However, when the temperature of the treatment liquid is increased, the scale of the treatment liquid is increased and the equipment such as the treatment tank is corroded severely, and the harmful effect becomes remarkable. Also, regarding the extension of the processing tank, the problem that the construction cost and the space are increased and the equipment cost is increased has become apparent. In addition, it is necessary to reduce the processing condition change time as much as possible from the viewpoint of low-volume, multi-product production, but the conventional method requires a lot of time and energy cost to raise and lower the temperature of the treatment liquid. there were.

[Means for solving problems]

The present invention has resulted in the following inventions as a result of intensive studies based on the above problems. That is, it is a method characterized in that a chemical treatment or an electrochemical treatment is carried out while heating a metal sheet or a web by induction heating in a treatment liquid. Further, the method is characterized in that the chemical treatment and the electrochemical treatment are performed while heating the metal sheet or the web by induction heating in the treatment liquid.

In the present invention, an aluminum plate is mainly used as the metal sheet or web for the support, but the material of the aluminum plate used is pure aluminum and aluminum alloy, and the latter is silicon, copper, iron,
There is an alloy whose main component is aluminum containing trace amounts of manganese, magnesium, chromium, zinc, lead, bismuth, nickel and the like. In any case, the purity of aluminum is 9
It can be said that it is preferably 9.0% or more.

Hereinafter, the present invention will be described in detail by roughening the aluminum plate, but the present invention is not limited to this and can be applied to other surface treatment of the aluminum plate, as well as other metals such as zinc and iron. It is also applicable to sheets or webs.

The lithographic printing plate produced from the aluminum plate made of the above-mentioned material is generally rectangular in shape because of the structure of the printing machine, but when the aluminum plate is treated according to the present invention, it is particularly mass-produced. In the case of the above scale, it is preferable to process as a web shape (strip shape), and after processing, it is cut into a desired rectangle.

The thickness of the aluminum plate is practically 0.1 to 0.1 in view of the tensile strength, proof stress, elongation, bending strength, etc. required when the lithographic printing plate produced thereby is bonded to a printing machine.
It is appropriately selected within the range of 0.5 mm.

Before performing the chemical treatment or electrochemical treatment of the present invention on the aluminum plate, it is preferable to perform mechanical graining in advance. The mechanical graining may be any mechanical polishing means capable of graining, for example, brush grain or the like.

A typical chemical treatment of the aluminum plate is a chemical etching treatment using an alkali such as caustic soda. In addition to alkali, etching may be performed with a solution that corrodes aluminum (for example, acids such as hydrofluoric acid, phosphoric acid, and sulfuric acid). Preferred alkaline agents are caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate and the like. It is appropriate that the concentration is 1 to 50% by weight, the temperature is from room temperature to 90 ° C, and the time is from 5 seconds to 5 minutes.
It is preferably selected to be in the range of 0.1 to 10 g / m ² .

Since a substance (smut) that is insoluble in alkali is present on the surface of an aluminum plate that has been alkali-etched in this way, an acidic solution (HNO ₃ , H ₂ SO ₄ , H ₃ PO ₄ solution, etc.)
Desmut processing is performed.

One example of the electrochemical treatment of aluminum plates is roughening.

The electrolytic solution used at this time is preferably hydrochloric acid, nitric acid or a mixed solution thereof. 0.1-10 wt%, more preferably 0.3-3 wt
% Solution in DC or AC. A rough surface is formed on the surface according to the amount of electricity used for electrolysis. The pit depth of the sand is 0.5 to 10μ, the pit diameter is 1 to 100μ, and more preferably the pit depth is 1 to 4μ and the pit diameter is 5 to 20.
is μ.

To form such a pit diameter, Japanese Patent Publication No. Sho 56-19280
It is more preferable to use the special alternating waveform described in JP-B No. 55-19191. That is, by controlling the electrolytic waveform, it is possible to economically and uniformly form the sand. Further, as disclosed in the specifications such as US Patent No. 3963564 and 3980539, amine, gluconic acid,
Boric acid, phosphoric acid, hydrofluoric acid, etc. may be added to the electrolytic solution.

Further, according to the present invention, after the aluminum plate is chemically treated, the above electrochemical treatment can be subsequently performed. The electrolytic solution used in the electrochemical treatment is the same as above, but a secondary rough surface is formed on the surface according to the amount of electricity used for electrolysis. The pit depth of the secondary sand is 0.1-1μ,
The pit diameter is 0.1 to 5μ, and more preferably the pit depth is
The pit diameter is 0.1 to 0.8 μ and the pit diameter is 0.3 to 3 μ. By controlling the electrolytic waveform, it is possible to economically and uniformly form the secondary grain.

A known induction heating device can be used for induction heating in these treatments, and the temperature of the aluminum plate in the treatment liquid can be adjusted by changing the amount of electric current passing therethrough.

It is preferable that the aluminum plate on which the secondary grain has been formed is subsequently treated with an acid or alkali solution. Specifically, in addition to the sulfuric acid described in Japanese Patent Publication No. 56-11316,
Phosphoric acid or a mixed solution of phosphoric acid and chromic acid is used. Further, the smut adhering to the surface is removed by lightly etching with an alkaline solution such as caustic soda as described in JP-B-48-28123. When the smut adhered with the alkaline solution is removed, the aluminum surface is etched, so that an insoluble component remains in the alkali. Therefore, it is necessary to desmut again with an acidic solution (sulfuric acid, phosphoric acid, chromic acid, etc.).

Further, the slurry liquid may be accelerated with high-pressure water to modify the grain shape by the brush grain method after primary grain formation, and then used as it is as a support for lithographic printing. An anodic oxide film may be formed on the surface of the intermediate layer or the aluminum in order to maintain stability or to improve the adhesion to the photosensitive layer, the printing durability, and the like. This treatment is also applied to supports with electrochemical grain overlays.

Here, the intermediate layer means U.S. Pat. Nos. 2,714,066 and 31,814.
As described in each specification of No. 61, it means an alkali metal silicate, a silicate layer by a dipping method afterwards with sodium silicate, or a hydrophilic undercoat layer such as CMC or PVA.

Examples of the electrolytic solution used for forming the anodic oxide film include phosphoric acid, chromic acid, oxalic acid, and benzenesulfonic acid, in addition to sulfuric acid.

Anodized film 0.1-10 g / m ² , more preferably 0.3-5 g / m ²
It is better to form it on the surface. It is preferable to perform alkali etching and desmutting treatment before the anodizing treatment.

The treatment conditions for anodization are not generally determined because they vary depending on the electrolyte solution used, but generally the concentration of the electrolyte solution is 1 to 80% by weight, the liquid temperature is 5 to 70 ° C, and the current density is 0.5.
Appropriate ranges are -60 A / cm ³ , voltage 1-100 V, and electrolysis time 10 seconds-5 minutes.

The grained aluminum plate with an anodized film thus obtained is stable in its self-stability and has excellent hydrophilicity, so it is possible to immediately apply a photosensitive coating on it, but if necessary, further surface Can be processed. For example, a silicate layer made of the alkali metal silicate described above or an undercoat layer made of a hydrophilic polymer compound can be provided. The coating amount of the undercoat layer is preferably 5 to 150 mg / m ² .

Then, a photosensitive coating film is provided on the thus treated aluminum support, and after image exposure, development and plate making, the plate is set in a printing machine to start printing.

Hereinafter, the details of the present invention will be described with reference to the drawings by taking the case of chemical treatment as an example. Reference numeral 1 is a metal web, 2 is a pass roll for conveying the web, and 3 is a draining nip device for not transferring the treatment liquid to the next step. Further, 4A and 4B are induction heating devices for heating the object to be heated 1, each coil is wound around each magnetic pole, and an alternating magnetic field applied to this coil generates an alternating magnetic field from each magnetic pole. When the metal web 1 which is the object to be heated 1 is placed in an alternating magnetic field, an eddy current flows in the object to be heated due to electromagnetic induction, and this eddy current generates Joule heat to heat the metal web 1. Reference numeral 5 is a treatment liquid, and 6 is a treatment tank.

〔Example〕

The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 A chemical treatment was performed using a mechanically roughened aluminum web. The mechanically roughened aluminum web had a central surface roughness of 0.6 μm, and when observed by an electron micrograph, protrusions called burrs were found everywhere.
This aluminum web is immersed in a 10% caustic soda solution heated to 20 ° C for 30 seconds so that the aluminum web is heated to 70 ° C by passing a current of 120A to the induction heating coil.
After washing with water, it was immersed in a 30% aqueous solution of 30% nitric acid for 90 seconds for neutralization, and thoroughly washed with water. The chemically treated aluminum web had a central surface roughness of 0.55μ, and no protrusions were observed when observed with an electron micrograph. After continuous treatment for 80 hours, no scale was generated in the treatment tank, and no scale-related failure occurred.

Comparative Example 1 The mechanically surface-roughened aluminum web used in Example 1 was immersed in a 10% caustic soda aqueous solution warmed to 70 ° C. for 30 seconds and washed with water. 90 in nitric acid solution
It was immersed for 2 seconds for neutralization, and washed thoroughly with water. The treated aluminum web had a surface roughness of 0.55 μm as in Example 1.
Then, there was no protrusion. However, after 80 hours of continuous treatment, scales were generated everywhere, and many scale failures occurred.

[Example 2] Immersion in a 10% caustic soda aqueous solution warmed to 70 ° C for 30 seconds, washing with water, and then immersion in a 30% nitric acid aqueous solution for 90 seconds for neutralization,
The aluminum web, which has been thoroughly washed with water, is held in a 0.7% nitric acid aqueous solution at 20 ° C so that the aluminum web is heated to 60 ° C by passing a current of 100 A through an induction heating coil.
Electrochemical treatment was performed using the alternating waveform current described in Japanese Patent No. 19191 to roughen the surface. Electrolysis conditions are V _A = 12.7 volts,
V _C = 9.1 V and the amount of electricity at the anode was set to 700 clones / dm ² . The roughened aluminum web had a center surface roughness of 0.52μ and a uniform grain. After continuous treatment for 80 hours, no scale was generated in the nitric acid tank.

[Example 3] In an aqueous 10% caustic soda solution warmed to 20 ° C, a current of 120A was applied to an induction heating coil so that the aluminum web became 70 ° C.
Soak it for 30 seconds so that it will be heated to 30 ° C, wash it with water, and
% Of nitric acid aqueous solution for 90 seconds to neutralize and wash the aluminum web thoroughly in 20% 0.7% nitric acid aqueous solution, and keep the aluminum web heated to 60 ° C by passing 100A current through the induction heating coil. The surface was roughened by electrochemical treatment using an alternating waveform current described in JP-B-55-19191. The electrolysis conditions were V _A = 12.7 V, V _C = 9.1 V, and the amount of electricity at the anode was 700 clones / dm ² . The roughened aluminum web had a center surface roughness of 0.52μ and a uniform grain. After 80 hours of continuous treatment, the induction heating treatment tank had no scale and no scale failure.

[Comparative Example 2] The same treatment as in Examples 2 and 3 was carried out by keeping caustic soda at 70 ° C and nitric acid solution at 60 ° C without using induction heating. In about 10 hours, scale occurred and many failures occurred.

〔The invention's effect〕

As described above, by inductively heating the metal sheet or the web, the reaction rate is increased, and yet it is not necessary to raise the temperature of the treatment liquid itself, so that the generation of scale,
Also, there is no corrosion of materials. Further, since the temperature of the metal sheet or the web itself can be easily changed, the next process under different processing conditions can be performed in a shorter time than changing the temperature of the processing liquid itself.

[Brief description of drawings]

FIG. 1 shows an apparatus for carrying out the chemical treatment of the present invention. 1: Metal web, 2: Pass roll 3: Draining nip device, 4A, 4B: Induction heating device 5: Treatment liquid, 6: Treatment tank

Claims (2)

[Claims] 1. A method for producing a lithographic printing plate support, which comprises performing a chemical treatment or an electrochemical treatment while heating a metal sheet or a web by induction heating in a treatment liquid. 2. A process for producing a lithographic printing plate support, which comprises performing a chemical treatment and an electrochemical treatment while heating a metal sheet or a web by induction heating in a treatment liquid.