JP3066685B2 - Method for producing a lithographic printing plate support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support for a printing plate, and more particularly to a method for producing a support for a lithographic printing plate comprising a roughened aluminum plate suitable for an offset printing plate.

[0002]

2. Description of the Related Art Conventionally, an aluminum plate has been widely used as a support for a lithographic printing plate. However, a lithographic printing plate which has good adhesion to a photosensitive layer provided thereon and is manufactured using the same. Improve the water retention of the non-image area of the plate (the area that receives the fountain solution used during printing and repels the oil-based ink, and the area where the surface of the support is exposed plays a role). For the purpose, the surface of the aluminum plate is usually roughened. This surface roughening treatment is called so-called graining, and is an indispensable step in the preparation of a lithographic printing plate support, and is an operation requiring considerable skill. This graining is roughly classified into a mechanical graining method such as ball grain, wire grain, and brush grain, and an electrical graining method. In the case of ball grains, there are many factors that require skill, such as the material of the ball, the type of abrasive, and the adjustment of water during polishing, and it is not possible to perform the work continuously, so it is necessary to finish each piece one by one. is there. In addition, the grain obtained from the wire grain is not uniform. On the other hand, the brush grain is an improvement of these methods, and is suitable for mass production because a uniform grain can be obtained and continuous treatment is possible. However, it has been difficult for the above-mentioned mechanical method to obtain sufficient performance as a support for a lithographic printing plate. It is generally said that a large surface roughness improves the water holding property (that is, water retention). When preparing a lithographic printing plate for improving water holding property and facilitating printing, the support of the support is required. It is said that the surface shape is preferably as uniform as possible.
As a method for obtaining such a preferable surface shape, attention has been paid to an electrochemical surface roughening method. According to this method, an aluminum plate having a constant roughened surface can be obtained if various conditions such as the composition of the electrolytic solution, the temperature, and the electrolytic conditions are kept constant. The width is so narrow that it is very difficult to adjust and electrolyze to always keep within such a range. Electrochemical surface roughening is also problematic from an economical point of view because of its large power consumption. In addition, due to the electrolysis, a considerable amount of aluminum ions are accumulated in the electrolytic solution, and there is a drawback that the labor cost and the chemical cost for the treatment of this waste solution reach a considerable amount. As a method for forming irregularities on the aluminum surface, a method using a roll having a reversal graining surface is known in JP-A-55-74898. There is a drawback that it is very difficult to form a reversible graining surface. JP-A-60-36195
In Japanese Patent Application Laid-Open No. 60-36196, a long-axis average length of 10 to 140 μm and a short-axis average length of 7 to 80 μm are formed. A method for forming fine irregularities of 10 μm is described. Japanese Patent Application Laid-Open No. Sho 60-203496 describes an aluminum plate in which irregularities having an average diameter of 10 to 100 μm are transferred by an embossed roll and then subjected to a chemical etching treatment and an electrochemical etching treatment.

[0003]

However, a method of manufacturing a lithographic printing plate support in which an uneven surface is pressed against an aluminum plate and the surface of the aluminum plate is unevenly formed by transfer is performed by using a rolling roller having unevenness. Although various proposals have been made, it has been difficult to accurately process sufficiently uniform and fine irregularities suitable for an aluminum support for a printing plate on the roller surface. In addition, it is difficult to increase the processing accuracy such as the cylindricity of the transfer roller. Even if the processing accuracy is improved, the cylindricity of the transfer roller changes during one transfer. Therefore, when attempting to transfer fine irregularities on the surface of the transfer roller to the aluminum plate, the rolling reduction must be set high, and there is a large problem in controlling the thickness change, elongation, etc. of the aluminum plate.

[0004] An object of the present invention is to solve the above-mentioned problems, there is no need to stick to the processing accuracy such as cylindricity of the transfer roll, and it is not necessary to control the thickness change and elongation of the aluminum plate.
An object of the present invention is to provide a method for producing a lithographic printing plate support having sufficiently uniform irregularities suitable as a printing plate support.

[0005]

The object of the present invention is to provide a method for manufacturing a lithographic printing plate support, in which an uneven surface is pressed against an aluminum plate and the surface of the aluminum plate is unevenly formed by transfer. The irregular surface is coated with fine particles
By repeating the transfer four or more times, there is no need to stick to the processing accuracy such as the cylindricity of the transfer roll, the elongation of the aluminum plate is reduced, and the coarse support is sufficiently uniform as an aluminum support for a printing plate. It has been found that a surface can be obtained, leading to the present invention. That is, the object of the present invention is to provide a method for manufacturing a lithographic printing plate support in which the uneven surface is pressed against an aluminum plate and the surface of the aluminum plate is unevenly formed by transfer, wherein the uneven surface is coated with fine particles.
Are those obtained, are preferably achieved by the process for producing a lithographic printing plate support, characterized in that repeated more than 4 times times the transcription.

[0006] In the present invention, that repeated more than 4 times times the transcription, a surface having irregularities coated fine fine particles, an aluminum plate is surface contact, 4 than on the more times
This refers to applying an upper repetitive pressure to repeatedly transfer a concavo-convex pattern corresponding to the average diameter of fine particles to an aluminum plate four or more times. Rolling roughened aluminum surface by shooting, chemically or electrochemically etching treatment in an aqueous solution of an acid or alkali or a neutral salt, using an alternating or direct current or pulsed direct current in acid or neutral salt solution When the surface is electrochemically roughened, it becomes more suitable as a support for a printing plate. A method of forming irregularities on an aluminum plate by performing etching treatment chemically or electrochemically after making the surface uneven by transfer, and then performing electrochemical surface roughening treatment,
The surface after the etching treatment preferably has irregularities with an average diameter of 4 to 20 μm (more preferably, irregularities with an average diameter of 4 to 10 μm). After electrochemically roughening, the surface after etching has an average diameter of 1 to
It is preferable that irregularities of 3 μm overlap. As a specific METHODS of the present invention, the surface having irregularities coated with fine particles, a paper as a support, a polyethylene film or the surface of the metal roll were dispersed fine particles of diameter 0.3~20μm It can be provided by applying and drying a liquid, or by applying and drying a liquid in which fine particles are dispersed directly on an aluminum plate. The liquid in which fine particles are dispersed refers to a liquid in which an adhesive binder and fine particles are dispersed in water or a solvent, or a liquid in which only fine particles are dispersed in water or a solvent. A thickener may be added as needed to adjust the viscosity of the liquid. As the liquid for dispersing the fine particles, a liquid mainly composed of water is preferable from the viewpoint of pollution and safety. As one of the specific methods of the present invention, pressure is applied to the uneven surface coated with fine particles, and the aluminum plate and the surface where the fine particles are applied to the sheet and dried to transfer the uneven pattern to the aluminum plate. combined bets, between two rolls with a narrow gap than the thickness of the aluminum plate was combined the sheet or by passage through the nip rolls, the concavo-convex pattern to an aluminum surface in contact with the particle surface of the sheet by applying pressure between the aluminum / sheet the Ru is transferred. Or, a fine particle is coated onto the roll surface, but it may also be transferred by applying a pressure to the roll surface on the aluminum plate. The fine particles used in the present invention are particles having a diameter of 0.3 to 20 μm, and preferably 3 to 10 μm, for example, alumina, sand, diamond, silicon oxide, silicon carbide, zirconia, etc. Is preferred. The particle size distribution is not preferable that the as much as possible aligned.

[0007] The aluminum plate having the irregular pattern transferred onto the surface of the aluminum plate is then chemically or electrochemically etched in an aqueous solution of an acid, an alkali, or a neutral salt to further support the printing plate. It becomes suitable. The above acidic aqueous solution refers to an aqueous solution mainly composed of hydrochloric acid, sulfuric acid, and nitric acid. The alkaline aqueous solution refers to an aqueous solution mainly composed of caustic soda. Processing time is 5
~ 120 seconds is preferred. The concentration is preferably from 1 to 40%. The liquid temperature is preferably from 35 to 75 ° C. If necessary, the aluminum plate may be subjected to a cathodic electrolytic cleaning treatment in an acid or alkali aqueous solution. The aqueous neutral salt solution is an alkali metal halide or an alkali metal nitrate, and is preferably sodium chloride, sodium nitrate, or sodium sulfate. P
H is preferably 5 to 9. The concentration is preferably from 1 to 40%. The liquid temperature is preferably from 35 to 75 ° C. When a neutral salt aqueous solution is used, it is necessary to perform an electrolytic treatment using an aluminum plate as a cathode. The cathodic electrolysis time is preferably from 5 to 180 seconds. The aluminum plate treated in a neutral salt or alkali aqueous solution is preferably further immersed in an aqueous solution of sulfuric acid, nitric acid or hydrochloric acid for the purpose of removing smut components formed on the surface.

The aluminum plate thus treated may be further subjected to an electrochemical surface roughening treatment. An electrochemical surface roughening method is disclosed in Japanese Patent Application Laid-Open No. 53-145701, in which an electrolytic solution is electrochemically surface-roughened using an alternating current in an acidic aqueous solution.
Japanese Patent Application No. Hei 3-65 discloses a method of electrochemically surface-roughening an acidic aqueous solution using a direct current in an aqueous solution as described in Japanese Patent Application Laid-Open Publication No. HEI 7-163, 1993.
A method of electrochemically performing a surface roughening treatment in a neutral salt aqueous solution as described in JP-A No. 06-2006 is known.
After performing electrochemical surface roughening treatment, desmut treatment in acidic aqueous solution, denaturation treatment in alkaline aqueous solution,
It is preferable to carry out a denaturation treatment using an aluminum plate as a cathode in a neutral salt aqueous solution. The desmut treatment in an acidic aqueous solution is known in JP-A-53-12739 and the like. Modification treatment in an alkaline aqueous solution is disclosed in
It is publicly known, for example, in Japanese Patent Application Publication No. The modification treatment in a neutral salt aqueous solution is known in JP-A-59-11295.

Further, the aluminum plate thus treated can be subjected to anodizing treatment in an electrolytic solution containing sulfuric acid or phosphoric acid by a conventional method in order to improve hydrophilicity, water retention and printing resistance. . Further, a sealing treatment can be performed after the anodic oxidation treatment. Furthermore, it can be immersed in an aqueous solution containing sodium silicate or the like to perform a hydrophilic treatment.

As the aluminum plate used in the present invention, either a pure aluminum plate or an aluminum alloy plate can be used.

[0011]

Embodiments Embodiments of the present invention will be described, but the present invention is not limited to these embodiments. (Experimental Example-1) Fine particles having an average diameter of 4 μm were applied to paper.
The dried surface was stuck from above and below with a JIS1050 aluminum plate, passed once, three times, and six times between nip rolls to transfer the pattern of the surface coated with fine particles on the paper to the aluminum surface. The clearance of the nip roll at this time was set to be 0.05 mm narrower than the thickness when the paper and the aluminum plate were combined. The surface of the aluminum plate after the transfer is white, which indicates that the unevenness is formed on the entire surface. Its average surface roughness was 0.33 μm. The elongation percentage of the aluminum plate at this time was 1%. When this surface was observed with a scanning electron microscope, the average diameter was 4 μm.
The fine irregularities around the center were formed.
The repetitive transfer was insufficient as a support for a lithographic printing plate, and the transfer was repeated six times to form uniformly fine irregularities, which was suitable as a support for a lithographic printing plate.

(Experimental Example 2) A plastic sheet was coated with fine particles having an average diameter of 8 μm and dried.
A 050 aluminum plate is stuck from the top and bottom, and it passes through the nip roll once, twice, three times, four times, five times, and six times, and the pattern of the surface coated with fine particles on the plastic sheet is transferred to the aluminum surface. I let it. The clearance of the nip roller at this time was set to be 0.05 mm narrower than the thickness when the plastic sheet and the aluminum plate were combined. The surface of the aluminum plate after the transfer was white, indicating that irregularities were formed on the entire surface. Observation of this surface with a scanning electron microscope revealed that irregularities centered on an average diameter of 8 μm were uniformly and randomly arranged. However, the surface having irregularities suitable as an aluminum support for a lithographic printing plate was transferred four, five, or six times repeatedly. In addition, the concave portions formed on the surface of these aluminum plates had a complicated shape different from an oval shape. Also, no clear direction was recognized.

(Experimental Example 3) The aluminum plate roughened by transferring repeatedly six times in Experimental Example 1 was immersed in a 5% aqueous solution of sodium hydroxide at 45 ° C. for 15 seconds.
A chemical etching treatment for dissolving g / m ² was performed. After washing with water, it was further immersed in a 25% aqueous sulfuric acid solution at 60 ° C. for 15 seconds, and then washed with water. The aluminum plate was subjected to electrochemical surface roughening treatment in a 1% aqueous nitric acid solution at 40 ° C. with a rectangular wave alternating current having a duty ratio of 1: 1 and a current density of 50 A / dm ² for 6 seconds using carbon as a counter electrode, and washed with water. Then 5%
0.5 g / m ² of aluminum plate in aqueous sodium hydroxide solution
An etching process for dissolving was performed. Further, it was immersed in a 25% aqueous sulfuric acid solution at 60 ° C. for 120 seconds and washed with water.
Next, anodizing treatment was performed using a direct current at 33 ° C. with a 10% sulfuric acid aqueous solution, followed by washing with water. Observation of this surface with a scanning electron microscope revealed that 1
Unevenness of about 2 μm was formed uniformly. Its average surface roughness was 0.49 μm. When a photosensitive layer was applied to this aluminum plate to form a lithographic printing plate, the printing plate had good stain performance.

(Experimental Example 4) The surface of the paper on which the fine particles were applied and dried was stuck together from above and below with a JIS1050 aluminum plate, passed once between nip rolls, and the pattern of the surface where the fine particles were coated on the paper was changed to aluminum. The surface was transferred. The nip roll clearance at this time is 0.3 mm larger than the thickness when the paper and aluminum plate are combined.
Narrowed. The average diameter of the fine particles is 4 μm, 8 μm, 15
μm, 20 μm, and 30 μm. The elongation rate of the aluminum plate at this time was 20%. The surface of the aluminum plate after the transfer was white. The average surface roughness and the result of observation with a scanning electron microscope are shown in Table 1 together with Examples-1 and 2.

[0015]

[Table 1]

From Table 1, each sample of Experimental Example-4 has an upper limit particle size of 20 as a fine particle size in the column of evaluation of fine particle shape.
It can be seen that it is about μm, preferably 4 to 8 μm. However, their average surface roughness is all too high for a good lithographic printing plate support. Also, since the elongation of aluminum is as high as 20%, the thickness of the aluminum plate changes accordingly, which is not preferable in terms of quality assurance.

(Experimental Example-5) The surface of an aluminum plate was polished and roughened with a Paminston suspension and a No. 8 nylon brush. Observation of the surface of this aluminum plate with a scanning electron microscope revealed that there was a non-uniform elongated narrow recess having a direction of about 10 μm to 20 μm. Each pit was not independent.
This aluminum plate was immersed in a 5% aqueous solution of caustic soda, and a chemical etching treatment was performed so that the aluminum plate dissolved at 1 g / m ² . After washing with water, it was further immersed in a 25% aqueous sulfuric acid solution at 60 ° C. for 15 seconds, and then washed with water.
Observation of the surface of this aluminum plate with a scanning electron microscope revealed that the concave portions having an average pitch of about 5 μm to 20 μm overlapped and existed unevenly. The aluminum plate was placed in a 1% aqueous solution of nitric acid at 40 ° C. with carbon
Electrochemical surface roughening treatment was performed with a rectangular wave alternating current having a UTY ratio of 1: 1 and a current density of 50 A / dm ² for 6 seconds, followed by washing with water. Next, an aluminum plate was weighed in an amount of 0.5 g /
Etching to dissolve m ² was performed. Further, anodizing treatment was performed using a direct current at 33 ° C. and a 10% sulfuric acid aqueous solution, followed by washing with water. Observation of this surface with a scanning electron microscope revealed that unevenness of 1 to 2 μm was uniformly generated in large unevenness of 5 to 20 μm. Its average surface roughness was 0.55 μm. When a photosensitive layer was applied to this aluminum plate to form a lithographic printing plate, the stain performance was inferior to that of Experimental Example-3 (the surface of Experimental Example-1).

[0018]

According to the present invention, the surface of the aluminum plate is made uneven by the transfer by pressing, and the transfer by the press is repeated at least four times to suppress the elongation of the aluminum plate, and have a non-directional average diameter of 3 mm. An aluminum support for a lithographic printing plate having a sufficiently uniform concave portion of 10 to 10 μm can be produced.

[Brief description of the drawings]

FIG. 1 shows the results of Experiment No. Group of 2-5 (Example-4)
It is a photograph of the fine pattern formed on the board . (375x magnification)

FIG. 2 shows a fine pattern formed on a substrate roughened with a nylon brush of Experimental Example-5 (Comparative Example 11).
It is a photograph of. (375x magnification)

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Claims (1)

(57) [Claims] The method according to claim 1] uneven surface was pressed against the aluminum plate, in the production method of the lithographic printing plate support to give an uneven surface of the aluminum plate by transfer, concave convex fine particles
The transfer is repeated four times or more.
A method for producing a lithographic printing plate support.