JP2000015945A - Manufacture of support for lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a support for a lithographic printing plate which reduces a loss of chemicals and a loss of electric energy and further treats uniformly a surface to be treated, by treating only a surface to be roughened as the lithographic printing plate. SOLUTION: In a manufacturing method wherein a support for a lithographic printing plate is obtained by roughening a surface of an aluminum sheet by chemical polishing and/or an electrochemical means, a reaction inhibiting layer for protecting the aluminum sheet from treatment in a manufacturing process for obtaining the support for the lithographic printing plate is provided on a surface not to be treated of the aluminum sheet before the treatment.

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 plate for a support of a photosensitive lithographic printing plate, and more particularly, to a technique for protecting a non-processed surface in a surface roughening process of the aluminum plate.

[0002]

2. Description of the Related Art A photosensitive lithographic printing plate is one in which a photosensitive layer is provided on a hydrophilic support. After exposing the photosensitive layer imagewise, the photosensitive layer is removed imagewise by a development treatment, and the photosensitive layer is removed. A lithographic printing plate is obtained in which the ink-receptive photosensitive layer which is not used is used as an image portion and the portion where the photosensitive layer is removed and the support is exposed is used as a non-image portion. As such a lithographic printing plate support, an aluminum plate having high hydrophilicity is usually used, and the surface on which the photosensitive layer is provided is roughened in order to obtain further hydrophilicity.
The surface treatment step including this roughening is called a graining step.

The graining process of an aluminum plate includes a degreasing process in which chemical polishing is performed using an alkaline solution, a neutralizing process in which an acidic solution is used, an electrolytic surface roughening process in which electrochemical polishing is performed in an acidic solution by alternating current electrolysis, and an alkali polishing process. A desmutting step of performing chemical polishing with a solution, a second neutralization step with an acidic solution,
It includes an anodic oxidation treatment step of obtaining an oxide film by DC electrolysis in an acidic solution, a post-treatment step of performing surface modification and hydrophilic treatment with various chemicals, and the like.

[0004]

In the degreasing step and the desmutting step, in which the aluminum surface is chemically dissolved and polished in an alkaline solution, the back surface of the aluminum plate, which does not need to be treated, has about the same amount of dissolution as the treated surface. proceed. For this reason, the amount of the alkali solution to be consumed and the amount of aluminum dissolved in the alkali solution are required to be twice as much as originally required.

[0005] In the electrolytic surface roughening step and the anodizing step of electrochemically treating an aluminum plate, the current to be supplied is not selectively applied only to the treated surface, but rather from the width end face of the aluminum plate. The wraparound occurs on the non-processed back surface. Therefore, it is necessary to supply more electric energy than the energy corresponding to the originally required processing amount. In addition, the processing surface near the edge of the aluminum plate where the wraparound occurs is insufficiently processed due to the wraparound of the current to the back surface, and the quality of the lithographic printing plate to be completed is impaired.

Japanese Patent Laid-Open Publication No. Hei 6-207299 discloses a method of suppressing the current from flowing into the back surface in the step of electrochemically treating the aluminum plate. The wraparound cannot be completely suppressed.

An object of the present invention is to provide a lithographic printing plate support in which only the surface to be roughened as a lithographic printing plate is treated to reduce the loss of a chemical solution and the loss of electric energy and to treat the treated surface uniformly. Is to provide a method of manufacturing the same.

[0008]

The object of the present invention is achieved by the following constitutions (1) to (8).

(1) A method for producing a lithographic printing plate support by a graining treatment step including a treatment step of chemically polishing the surface of an aluminum plate and / or a treatment step of electrochemically roughening the surface of the aluminum plate. A method for producing a lithographic printing plate support, comprising: providing a reaction suppression layer for protecting the aluminum plate from the treatment in the graining step on the non-treated surface of the aluminum plate before the graining step.

(2) The method for producing a lithographic printing plate support as described in (1) above, wherein a step of providing a reaction suppressing layer is included in the graining step.

(3) The method according to (2), wherein the step of providing the reaction suppression layer is performed between the unwinding step of the untreated aluminum plate in the graining step and the first immersion step in an aqueous solution. A method for producing a support for a lithographic printing plate as described above.

(4) The method for producing a lithographic printing plate support as described in (1) above, wherein the step of providing a reaction suppression layer is provided separately from the graining step.

(5) The method for producing a lithographic printing plate support according to any one of the above (1) to (4), wherein the means for providing the reaction suppression layer is by applying a liquid.

(6) The method for producing a lithographic printing plate support as described in (5) above, wherein the reaction suppressing layer after coating is dried in a drying step provided immediately after the coating step.

(7) The method for producing a lithographic printing plate support according to any one of the above (1) to (4), wherein the means for providing the reaction suppression layer is a laminate.

(8) The method according to (1) to (1), further comprising a step of peeling off the reaction suppression layer after the completion of the graining step.
The method for producing a lithographic printing plate support according to any one of (7) and (8).

Preferred embodiments of the present invention include a mode in which the reaction suppressing layer is a resin layer containing a polymer resin, and a mode in which the peeled reaction suppressing layer is laminated again.

Hereinafter, the present invention will be described in detail.

FIG. 1 is a flow chart of the graining process of a general lithographic printing plate support to which the inventions of claims 1 to 8 are applied. The graining treatment is performed through the following steps.

The coiled aluminum plate is unwound with an unwinder, and is immersed in an alkaline chemical solution in the degreasing step A to dissolve and remove oil and resin adhering to the surface during rolling of the aluminum coil. As the alkaline solution used here, an aqueous solution of sodium hydroxide or potassium hydroxide is used.

Next, the aluminum plate is immersed in the first neutralization step B using an acidic aqueous solution as a treatment liquid, and an alkali component on the surface is removed by a neutralization reaction.

In the electrolytic surface roughening step C, the surface is roughened by passing a current between the electrode plate and the aluminum plate disposed at a position facing the aluminum plate via an acidic electrolytic solution.
As the acidic electrolyte used here, nitric acid or hydrochloric acid or various acids containing these are used. Generally, a commercial alternating current is used as the current to be used, but an alternating current having a waveform processed like a rectangular wave, a sawtooth wave, or a trapezoidal wave is also used.

The roughened aluminum plate is immersed in an alkaline solution in a desmutting step D in order to remove smut generated on the surface of the aluminum sheet in the electrolytic roughening step C. As the alkaline solution used here, an aqueous solution of sodium hydroxide or potassium hydroxide is used.

Next, in a second neutralization step E, the aluminum plate is immersed in an acidic aqueous solution to remove an alkali component on the surface by a neutralization reaction.

Next, the aluminum plate is transported to an anodic oxidation step F, and an anodic oxidation treatment is performed in which an aluminum oxide layer is formed on the aluminum surface by passing a direct current between the aluminum plate and the opposing electrode plate in an acidic solution. Is applied. As the acidic solution used here, sulfuric acid, phosphoric acid or a mixed acid thereof is used. DC current is applied so that the aluminum plate becomes an anode.

The aluminum plate which has been subjected to the anodizing treatment is subjected to a surface modification treatment such as a sealing treatment or a hydrophilic treatment in a post-treatment step G, if necessary, to complete a lithographic printing plate support.

In the graining process, each process is performed by immersing an aluminum plate in a treatment tank containing a chemical solution or an electrolytic solution (hereinafter, these may be collectively referred to as “treatment solution”). A water washing treatment is provided between these treatment tanks as necessary to prevent the treatment liquid from being carried into the next step.

Since the graining process of the aluminum plate for a lithographic printing plate support varies widely, the target of protecting the aluminum plate from the graining process is different in each of the treating processes. In the degreasing step in which the aluminum plate is immersed in an alkaline solution, and in the desmutting step, the aluminum is dissolved.In an acidic solution, an alternating current is passed between the aluminum plate and the electrode plate facing the aluminum plate to form an aluminum plate. In the electrolytic surface roughening step of roughening the surface, electropolishing of an aluminum plate is performed, and a direct current is applied between the aluminum plate and an electrode plate facing the aluminum plate in an acidic solution so that the surface of the aluminum plate is roughened. In the anodic oxidation step of forming an oxide film, an oxide film is formed. In the post-treatment step of immersing the aluminum plate in various chemical solutions, the surface of the aluminum plate is altered and the adsorption of the chemical solution is protected.

The present invention is characterized in that a reaction suppression layer is previously provided on the non-processed surface of the aluminum plate in order to prevent the processing liquid from being consumed by the processing of the back surface of the aluminum plate in the graining process as described above. Is what you do.

The step of providing the reaction suppressing layer can be provided at the beginning of the graining step of the aluminum plate, that is, after the original winding of the aluminum plate is unwound and before the aluminum plate is conveyed to the first processing step. Alternatively, a separate process may be performed offline and a reaction suppression layer may be provided in advance.

The reaction suppressing layer is preferably one which is not affected by each processing step included in the graining step, and preferably contains a polymer resin. Specifically, phenolic resin,
Urea resin, melamine resin, unsaturated polyester resin,
Diallyl phthalate resin, epoxy resin, silicon resin,
Alkyd resin, polyimide, casein resin, furan resin, vinyl chloride resin, vinyl acetate resin, polyvinyl alcohol, polyvinyl butyral, polystyrene, ABS
Resin, methacrylic resin, polyphenylenoxide, polyurethane, ionomer resin, cellulosic resin, polyethylene, polypropylene, polyamide, polycarbonate, polyacetal, polyphenylene sulfide, vinylidene chloride resin, polyethylene terephthalate, fluorine resin, and the like.

One of the means for providing a reaction suppression layer is a method of applying a resin in a solution state to the back surface. The coating method is not particularly limited, and roll coating, die coating, spray coating, or the like can be used. After this coating step, a drying step is provided if necessary.

Another means for providing a reaction suppression layer is lamination. The desired reaction suppression layer is obtained by heat-sealing, bonding or sticking the sheet-like resin to the back surface of the aluminum plate.

With this reaction suppressing layer, the dissolution of aluminum in the degreasing step and the desmutting step, which are the chemical polishing steps, can be suppressed to about half, and the deterioration of the chemical solution can be suppressed to about half. In addition, it is possible to completely suppress the current from flowing to the back surface in the electrolytic surface roughening step and the anodizing step in which the electrochemical treatment is performed, reduce the power consumption, and suppress the deterioration of the chemical solution. In addition, uniform processing can be performed on the entire surface without processing shortage near the end of the processing surface.

The reaction-suppressing layer provided on the back surface usually peels off when the graining step of the support is completed. As the reaction suppression layer provided with the reaction suppression layer by the lamination treatment, the reaction suppression layer peeled off after finishing the graining process can be used again. That is, the peeled reaction suppression layer can be used again as a reaction suppression layer by heat-sealing, adhering or sticking to the back surface of the aluminum plate to be newly treated.

Further, the reaction-suppressing layer may be used as a part of a photosensitive lithographic printing plate as a product without peeling. After cutting the photosensitive lithographic printing plate, a plurality of sheets are cut into a single package and commercialized. However, in order to prevent the photosensitive layer from being damaged due to vibration during transportation and to prevent the printing plate from sticking due to pressure due to deposition, it is adjacent to the printing plate. It is common to insert a slip sheet between two photosensitive lithographic printing plates. Normally, after the photosensitive layer of the photosensitive lithographic printing plate is coated, the mating process is applied as necessary, and the mating process is applied to the belt-shaped photosensitive lithographic printing plate, and the slipping paper fed from the winding state is overlapped. The photosensitive lithographic printing plate and the interleaf are overlapped and cut to a predetermined size. At this time, chips called paper dust are generated from the slip sheet,
It often becomes a foreign matter at the time of printing, which is a problem at a printing site. By leaving the reaction suppression layer, the function of the cushion layer and the sticking prevention layer can be imparted, and interleaving paper is not required.

The thickness of the reaction suppressing layer is not particularly limited, but is preferably 5 to 500 μm, and particularly preferably 20 to 200 μm.
μm.

[0038]

Example 1 An aluminum plate having a thickness of 0.3 mm and a material of 1050 was subjected to a weight-average molecular weight of 10
0000 polystyrene resin in methyl ethyl ketone
After a solution dissolved at a concentration of 0% by weight was applied by a die coating method, the solution was dried to provide a reaction suppression layer having a thickness of 20 μm. Then, after performing the following treatments in this order, a graining treatment was performed, and then the reaction suppression layer was peeled off.

Degreasing treatment: sodium hydroxide 100 g /
1, 85 ° C, 60 seconds Rinsing: distilled water, 25 ° C, 10 seconds Neutralization treatment: hydrochloric acid 1 g / l, 25 ° C, 10 seconds Roughening treatment: hydrochloric acid 15 g / l, 25 ° C, commercial AC 80
A / dm ² , 30 seconds Rinse: distilled water, 25 ° C., 10 seconds Desmut treatment: sodium hydroxide 100 g / l, 5
0 ° C, 10 seconds Rinsing: distilled water, 25 ° C, 10 seconds Neutralization: sulfuric acid 100g / l, 25 ° C, 10 seconds Anodizing treatment: sulfuric acid 200g / l, 25 ° C, DC 3A
/ Dm ² , 60 seconds Example 2 A polystyrene resin sheet having a thickness of 50 μm was adhered to a non-treated surface of an aluminum plate having a thickness of 0.3 mm and a material of 1050 using a laminator to obtain a reaction suppression layer. Then, after graining of the aluminum plate was performed under the same conditions as in Example 1,
The reaction suppression layer on the non-treated surface was peeled off.

Comparative Example An aluminum plate having a thickness of 0.3 mm and a material of 1050 was subjected to graining treatment on the aluminum plate under the same conditions as in Example 1 except that no reaction suppressing layer was provided on the non-treated surface.

In each of the above Examples and Comparative Examples, the amount of the chemical solution consumed in each treatment and the amount of the chemical solution flowing into the back surface of the electrolytic polishing treatment and the anodic oxidation treatment were measured. The results are shown in Table 1 below.

[0042]

[Table 1]

Example 3 The reaction suppression layer peeled off in Example 2 was bonded to a newly prepared non-treated surface of an aluminum plate having a thickness of 0.3 mm and made of a material 1050 by a laminator to provide a reaction suppression layer. After graining aluminum plate under conditions,
The reaction suppression layer on the non-treated surface was peeled off. The same result as in Example 2 was obtained as a result of measuring the consumption amount of the chemical solution in each treatment and the wraparound to the back surface of the electrolytic polishing treatment and the anodic oxidation treatment.

[0044]

According to the present invention, a lithographic printing plate for treating only a surface to be roughened as a lithographic printing plate, thereby reducing loss of a chemical solution and electric energy, and uniformly treating the treated surface. A method for manufacturing a support is provided.

[Brief description of the drawings]

FIG. 1 is a flowchart of a general graining process of an aluminum plate to which the present invention is applied.

[Explanation of symbols]

 A degreasing step B first neutralizing step C electrolytic surface roughening step D desmutting step E second neutralizing step F anodizing step G post-processing step

Claims (8)

[Claims] 1. A method for producing a lithographic printing plate support by a graining treatment step including a treatment step of chemically polishing a surface of an aluminum plate and / or a treatment step of electrochemically roughening the surface of the aluminum plate. A method for producing a lithographic printing plate support, comprising: providing a non-treated surface of an aluminum plate before a treatment step with a reaction suppression layer for protecting the aluminum plate from the graining treatment. 2. The method for producing a lithographic printing plate support according to claim 1, further comprising the step of providing a reaction suppression layer during the graining step. 3. The lithographic plate according to claim 2, wherein the step of providing the reaction suppression layer is between the unwinding step of the untreated aluminum plate in the graining step and the first immersion step in an aqueous solution. A method for producing a printing plate support. 4. The method for producing a lithographic printing plate support according to claim 1, wherein a step of providing a reaction suppression layer is provided separately from the graining step. 5. The method for producing a lithographic printing plate support according to claim 1, wherein the means for providing the reaction suppression layer is by applying a liquid. 6. The method for producing a lithographic printing plate support according to claim 5, wherein the reaction suppression layer after the application is dried in a drying step provided immediately after the application step. 7. The method for producing a lithographic printing plate support according to claim 1, wherein the means for providing a reaction suppression layer is a laminate. 8. The method for producing a lithographic printing plate support according to claim 1, further comprising a step of peeling off the reaction suppression layer after the graining step is completed.