JPH07205565A - Manufacture of support body for lithographic form plate - Google Patents

Abstract

PURPOSE:To obtain excellent performance in transferring without untransferred parts or with a little untransferred parts even under a low pressure. CONSTITUTION:Transferring on the surface of an aluminum board 10 is performed by using a transfer roller 13 such that an area ratio of a transfer recess 11 becomes 5-70%. Next, aftertreatment is done by chemical etching, electrochemical etching, or combination of the chemical etching and electrochemical etching so as to reduce untransferred parts 12 on the surface of the aluminum board 10 and heighten the area ratio of the transfer recess 11 to 75% or above.

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 a lithographic printing plate support, and more particularly to a lithographic printing plate support comprising a roughened aluminum plate or aluminum alloy plate suitable for offset printing plates. It is about.

[0002]

2. Description of the Related Art Conventionally, aluminum plates (including aluminum alloy plates) have been widely used as a support for lithographic printing plates, but they have good adhesiveness to a photosensitive layer provided thereon and The non-image area of the lithographic printing plate prepared by using (the area which receives the fountain solution used at the time of printing and repels the oil-based ink, and the area where the surface of the support is exposed bears this). The surface of the aluminum plate is usually roughened for the purpose of improving water retention. This roughening process is called so-called graining,
It is an indispensable step in the preparation of a lithographic printing plate support,
Moreover, it is a work that requires a considerable degree of skill. This graining is a mechanical graining method such as ball grain, wire grain, brush grain, a chemical graining method in which etching treatment is performed with an acid or an alkali, or an electrochemical method in which electrolysis is performed in an acid or alkali aqueous solution. The roughening method is used.

Among the mechanical graining methods, in the case of ball grain, there are many factors that require skill, such as the material of the ball, the type of abrasive, the adjustment of water content during polishing, and the work is carried out continuously. It is impossible and it is necessary to finish each one. Further, the wire grain has a drawback that the obtained grain is not uniform. On the other hand, brush grain is an improved version of these methods and is suitable for mass production because it provides a uniform grain and is capable of continuous treatment. The demand for high-performance lithographic printing plate supports has not been adequately met. Further, in these mechanical surface roughening methods, work is required to remove the abrasives, aluminum debris, etc. that have bitten into the surface of the roughened aluminum plate, and therefore workability is also poor. On the other hand, according to the chemical surface roughening method and the electrochemical surface roughening method, it is possible to form a uniform uneven surface as compared with the mechanical surface roughening method, but the chemical surface roughening method Regarding, regarding the temperature and composition of the etching solution, the problem that the etching conditions such as processing time must be maintained within a certain range, in addition to the problem of waste solution processing, and the electrochemical roughening method. Regarding the above, there is a problem from the economical point of view in addition to the problem that the chemical surface roughening method has, and the large power consumption. Further, a method in which a mechanical surface roughening method and a chemical or electrochemical surface roughening method are used in combination has been proposed, but it has the same problem.

Therefore, as a method capable of solving the problems of the mechanical, chemical or electrochemical surface roughening method, by rolling an aluminum plate with a roughened roll,
A method has been proposed in which a rough surface pattern of a roller is transferred to an aluminum plate to roughen the surface. This method is disclosed in, for example, Japanese Patent Laid-Open No.
5-74898, Japanese Patent Laid-Open No. 61-162351 and Japanese Patent Publication No. 4-30358, and according to these known materials, a roll having an inverted graining surface formed by sandblasting, grid injection, electric discharge machining, etc.
(A transfer roller) is used to roll an aluminum plate, which is an object to be transferred, under a predetermined reduction ratio, and the rough surface pattern of the transfer roller is transferred to the surface of the aluminum plate. Furthermore, JP-A-60-
36195 and Japanese Patent Laid-Open No. 60-36196 disclose that the long axis average length is 10 to 140 on the surface of an aluminum plate.
1 μm by a chemical or electrochemical treatment after forming an oval-shaped press recess having a short axis average length of 7 to 80 μm.
A method for forming fine unevenness of 10 μm is described.
Further, in JP-A-60-203496, an aluminum plate which is rolled by a roll having an embossed surface with an average diameter of 10 to 100 μm, and then further subjected to a chemical etching treatment and an electrochemical etching treatment. Is written.

[0005]

By the way, generally, in a lithographic printing plate support, the recesses formed by roughening are uniform, and if the area is large, water retention, that is, water retention is improved, and printing is performed. There is a tendency that stains, printing unevenness, etc. are eliminated when the printing is performed and printing performance is excellent. Therefore, in the method that uses both transfer and etching as described above, it is necessary to press the transfer roller against the aluminum plate at a somewhat high reduction rate or to increase the etching amount. However, even if the transfer roller is transferred once, the convex portions on the surface are crushed and the cylindricity and the like change. Therefore, considering the life of the transfer roller, it is not preferable to set the rolling reduction too high. Also, by increasing the reduction rate,
The aluminum plate, which is the transferred material, is stretched, and the accuracy of the support as a whole is reduced. Since this stretching differs depending on the material, it is necessary to create and manage stretching data for each material, which complicates the work. On the other hand, when the transfer is carried out at a low reduction rate, a large amount of the flat surface portion where the concave portion is not formed on the surface of the aluminum plate, that is, a large amount of the untransferred portion remains, and is sufficient as the support for the lithographic printing plate even if the etching treatment is performed. A large concave area may not be obtained. Further, in order to reduce the untransferred portion, it is necessary to increase the etching amount, and as a result, a large amount of aluminum is dissolved in the waste liquid, and the waste liquid treatment requires great cost.

As described above, by setting the rolling reduction of the transfer roller to be low, the problems of the life of the transfer roller and the stretching of the aluminum plate can be avoided, but on the other hand, the surface of the aluminum plate has a certain size and area. There is a problem that the concave portion must be formed. An object of the present invention is to solve the above problems,
That is, it is an object of the present invention to provide a method for producing a support for a lithographic printing plate, which has good performance with little or no untransferred portion even when transferring at a low pressure rate.

[0007]

The above object of the present invention is to provide the surface area of an aluminum plate or an aluminum alloy plate with an area ratio of independent recesses of 5 to 5 using a transfer roller.
This is achieved by a method for producing a lithographic printing plate support characterized by increasing the area ratio of the recesses to 75% or more by performing post-treatment by chemical etching after transferring to 70%. . The same object can be achieved by using electrochemical etching as the post-treatment in the method for producing a lithographic printing plate support. The same object can also be achieved by performing the post-treatment in combination with chemical etching and electrochemical etching in the method for producing a lithographic printing plate support. According to the present invention, in the production of the lithographic printing plate support, the area ratio of the recesses formed on the surface of the aluminum plate by the transfer roller is set to a low value of 5 to 70%, and the area ratio of the recesses is set by the subsequent etching treatment. Is increased to 75% or more, it is possible to produce a support for a lithographic printing plate which has no untransferred portion or is excellent in stain performance even when transfer is performed at a low reduction rate. Further, by reducing the rolling reduction, it is possible to reduce the load on the transfer roller and extend the life of the transfer roller. The transfer roller used in the present invention is, for example, SUS304, SUS316, SCM.
A roller core made of steel, SUJ steel, SS41, or the like is provided with fine projections on the surface by thermal spraying, laser, machining, or the like.

In the method by thermal spraying, the particle size is 10 to 60 μm.
It is obtained by coating the surface of a roller with ceramic particles or a ceramics sintered body of a certain degree to a thickness of about 0.1 to 0.6 mm by plasma spraying, spraying with a DJ gun, or spraying with a wire, and polishing the surface. The types of ceramics include white alumina, gray alumina, a mixture of white alumina and titanium dioxide, a mixture of gray alumina and titanium dioxide, chromium oxide, a mixture of chromium oxide and titanium dioxide, a mixture of chromium oxide and silica, zirconia, titanium dioxide. Examples thereof include nitrides such as silicon nitride, and carbides. Among them, oxide ceramics containing chromium oxide as a main component and nitride ceramics containing silicon nitride as a main component are preferable from the viewpoint of strength. Further, since the roller surface formed by thermal spraying is rough, the maximum roughness is 0.01
The polishing process is performed so that the thickness is about 0.1 μm. on the other hand,
The method of forming convex portions by laser utilizes the fact that the laser-irradiated portion of the roller surface is melted and rises up. Thus, it is possible to form mutually independent convex portions cut out by the both grooves. Examples of the laser used include CO ₂ laser, YAG laser, excimer laser and the like. Further, the groove width formed varies depending on the type of laser, 40 μm or more for CO ₂ laser, 3 to 20 μm for YAG laser,
The excimer laser can form a groove having a width of about 1 to 20 μm. Therefore, it is necessary to select the type of laser according to the desired size of the convex portion, and it is necessary to use a laser having a short wavelength such as an excimer laser in order to obtain a transfer roller having a finer uneven shape. Further, since the convex portion formed by the laser has a width of approximately ± 1 to 6 μm, the deviation is ± 0.1 to 1.0 μ due to a diamond grindstone, a ceramic grindstone, or a polishing paper containing these.
It is finished to be about m.

Similarly, it is also possible to cut fine grooves in a grid pattern from two directions by using a die or a bite on the roller surface to form square irregularities. With such a method by machining, although the grid-like grooves can be easily formed,
The size of the convex portion is larger than that of the method using the thermal spraying or the laser. Further, the roller surface thus formed may be subjected to a treatment such that the corners are rounded by a known etching treatment or the like. Further, in order to increase the hardness of the surface, quenching or hard chrome plating may be applied. The protrusions on the surface of the transfer roller are formed as described above, and the size of the protrusions is 2 to 50 μm as an average diameter.
A degree is preferable. On the other hand, the aluminum plate or the aluminum alloy plate serving as the support is JIS 1050, 110
In addition to commercially available aluminum alloys such as 0, 3003 and the like, aluminum alloys containing iron, tin, indium, gallium, copper, magnesium, etc. are used as plate materials in order to facilitate chemical and electrochemical etching described later. The processed product can be used. Further, the form is not limited to the plate shape, and may be processed into a foil, strip, or film shape.

The aluminum plate or aluminum alloy plate is inserted between the transfer roller and a mirror-finished metal roller (backup roll), and
Under the linear pressing force of about 3 to 30 kg / mm, the uneven pattern composed of the convex portions of the transfer roller is transferred. FIG. 1 is a partially enlarged cross-sectional view showing a transfer result.
1 (corresponding to the convex portion 14 of the transfer roller 13) and the untransferred portion 12
And are formed. Although the surface of the transfer roller 13 is shown as a flat surface in FIG. 1, this figure shows an enlarged part of the surface of the transfer roller 13, and the cross-sectional shape of the actual transfer roller 13 is circular. Is. In the present invention, the area ratio of the recesses formed by transfer, that is, the ratio of the area of the transfer recesses 11 to the total area of the transfer recesses 11 and the untransferred portions 12 may be 5 to 70%. Thirteen
Does not need to be strongly pressed against the aluminum plate 10,
The rolling force can be reduced as compared with the conventional transfer method. Further, when the reduction ratio is low or the density of the convex portion of the transfer roller is low and the above area ratio cannot be achieved by one transfer, the area ratio of the concave portion can be reduced by repeating the transfer a plurality of times. You may raise it. Then, the surface of the aluminum 10 roughened by the transfer is subjected to chemical or electrochemical etching in an aqueous solution of acid, alkali or neutral salt, or an etching treatment in which both are combined.

Examples of the etching solution include acidic aqueous solutions of phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, alkaline aqueous solutions of sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium orthosilicate, sodium metasilicate,
A neutral aqueous solution composed of an alkali metal salt such as sodium monophosphate or sodium triphosphate can be used. Further, the etching treatment can be performed electrochemically. Specifically, as disclosed in JP-A-53-145701, a method of electrochemically roughening treatment using an alternating current in an acidic aqueous solution is described in JP-A-4-14094. Electrochemical surface roughening treatment using direct current in acidic aqueous solution, Japanese Patent Application No. 3-6506
It is possible to employ a known method such as a method of electrochemically roughening the surface in an aqueous neutral salt solution as described in the specification. Further, the chemical etching and the electrochemical etching may be combined and processed.
The conditions of these etching treatments differ depending on the material of the aluminum plate and the area ratio of the recesses due to transfer, and are appropriately selected so that the area ratio of the recesses after the etching treatment is 75% or more. As shown in FIG. 2, the surface of the aluminum plate 10 is enlarged by the etching process as described above, and the area of the recess 21 (transfer portion) is increased, and at the same time, the untransferred portion 12 is transferred.
The area becomes smaller, which makes it more suitable as a support for a lithographic printing plate.

After the etching treatment, a desmutting treatment in an acidic aqueous solution, a denaturing treatment in an alkaline aqueous solution, or a denaturing treatment using an aluminum plate as a cathode in a neutral salt aqueous solution may be performed. Regarding these treatments, desmut treatment in an acidic aqueous solution is disclosed in JP-A-53-12739, and modification treatment in an alkaline aqueous solution is disclosed in JP-A-56-13.
No. 9,700, etc., and denaturing treatment in an aqueous solution of a neutral salt is known from JP-A No. 59-11295.
These methods can also be adopted in the present invention. Further, the aluminum plate thus treated can be anodized in an electrolytic solution containing sulfuric acid or phosphoric acid by a conventional method in order to improve hydrophilicity, water retention and printing resistance. In addition, after the anodizing treatment, it is also possible to perform a sealing treatment or a hydrophilic treatment by immersing in a water solution containing sodium silicate or the like.

[0013]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. (Experimental Example-1) After polishing the surface of a SUS steel roll and performing mirror-finishing with a maximum roughness Ra of 0.03 μm, a vertical groove width of 5 μ was obtained by a YAG laser processing device with a rated output of 10 W.
m, lateral groove width 5 μm, groove interval 10 μm
A transfer roller was obtained by providing a plurality of independent convex portions each having a size of μm square. Using this transfer roller, JIS105
Transfer was performed on the 0 aluminum alloy plate under the conditions of linear rolling reduction force: 10 kg / mm and transfer frequency: 1 time. The area ratio of the recesses due to the transfer was 28%. Next, the aluminum alloy plate was subjected to a chemical etching treatment of 5.0 g / m ² with a sodium hydroxide aqueous solution having a concentration of 7 wt% and a liquid temperature of 60 ° C. The area ratio of the recesses after etching is 9
It was 6%. Further, the aluminum alloy plate is added to the
It was immersed in a 5 wt% sulfuric acid aqueous solution having a liquid temperature of 60 ° C. to remove the hydroxide formed on the surface, and washed with water. A micrograph of the surface of the obtained aluminum alloy plate is shown in FIG. This aluminum alloy plate was further treated with a concentration of 10 wt% and a liquid temperature of 3
Anodization was carried out in a sulfuric acid aqueous solution at 3 ° C. using a direct current with a current density of 2 A / dm ² , washed with water and dried to obtain a lithographic printing plate support.

The lithographic printing plate support was coated with a photosensitive solution having the following composition and dried to form a photosensitive layer. The coating weight of the photosensitive layer after coating was 2.0 g / m ² . Photosensitive solution: -Naphthoquinone-1,2-diazide-5-sulfonic acid ester of polyhydroxyphenyl obtained by condensation of acetone and pyrogallol ... 0.8 g-Novolak-type metapara-mixed cresol-formaldehyde resin ... 1.70 g- t-Butylphenol resin: 0.05 g Phthalic anhydride: 0.08 g 2-Trichloromethyl-5- (p-butoxystyryl) -1,3,4-oxadiazole: 0.06 g・ Crystal violet paratoluene sulfonate ・ ・ ・ 0.03 g ・ Propylene glycol monomethyl ether ・ ・ ・ 18.0 parts by weight ・ Methyl ethyl ketone ・ ・ ・ 12.0 parts by weight The photosensitive lithographic printing plate prepared in this manner was used as a metal halide lamp. As a light source for 60 seconds through a positive image film After exposure, manufactured by FUJIFILM developer DP-4 (1:
7), the rinse solution FR-2 (1: 7) was processed through an automatic processor to prepare a lithographic printing plate. The lithographic printing plate thus obtained was a very good printing plate with excellent stain performance.

(Experimental Example-2) In the same manner as in Example-1,
After obtaining an aluminum alloy plate in which the area ratio of the recesses before the etching treatment is 28%, the aluminum alloy plate is subjected to a concentration of 7%.
A 3.0 g / m ² chemical etching treatment was performed with a sodium hydroxide aqueous solution having a wt% and a liquid temperature of 60 ° C. The area ratio of the recesses after etching was 78%. Further, the aluminum alloy plate has a concentration of 25 wt% and a liquid temperature of 60 ° C.
The surface hydroxide was removed by immersing in a sulfuric acid aqueous solution of, and washed with water. This aluminum alloy plate was anodized in the same manner as in Example-1 to form a lithographic printing plate support, and then a photosensitive layer similar to that in Example-1 was provided to prepare a lithographic printing plate. The lithographic printing plate thus obtained was a good printing plate, although the stain performance was slightly inferior to that of the lithographic printing plate obtained in Example-1.

(Example 3) In the same manner as in Example-1, after obtaining an aluminum alloy plate having an area ratio of the recesses of 28% before the etching treatment, the aluminum alloy plate was subjected to a concentration of 1 w.
t%, aluminum ion concentration 0.5 wt%, liquid temperature 4
Electrochemical etching was performed in a nitric acid aqueous solution at 5 ° C. using a rectangular wave alternating current with a duty ratio (1: 1). The current condition is 160 C / dm ² , and the peak current density is 25
It was A / dm ² . The area ratio of the recesses after etching was 94%. This aluminum alloy plate is further anodized in a sulfuric acid aqueous solution having a concentration of 10 wt% and a liquid temperature of 33 ° C. using a direct current with a current density of 2 A / dm ² , washed with water and dried to obtain a support for a lithographic printing plate. It was The lithographic printing plate support was coated with the same photosensitive solution as in Example-1 and dried to form a photosensitive layer. The coating weight of the photosensitive layer after coating was 2.0 g / m ² . The lithographic printing plate thus obtained was a good printing plate with excellent stain performance.

(Example 4) In the same manner as in Example-1, an aluminum alloy plate having an area ratio of recesses before etching of 28% was obtained, and then the aluminum alloy plate was first subjected to a concentration of 7 wt% and a liquid temperature. A chemical etching treatment of 1.0 g / m ² was performed with an aqueous sodium hydroxide solution at 50 ° C. Further, the aluminum alloy plate was immersed in a sulfuric acid aqueous solution having a concentration of 25 wt% and a liquid temperature of 60 ° C. to remove the hydroxide formed on the surface, and washed with water. Further, this aluminum alloy plate was treated with a concentration of 1 wt% and an aluminum ion concentration of 0.5 wt.
%, In a nitric acid aqueous solution with a liquid temperature of 45 ° C., using a rectangular wave alternating current with a duty ratio (1: 1), 135 C / dm ² ,
Electrochemical etching was performed under the conditions of a peak current density of 25 A / dm ² . The area ratio of the recesses after etching is 9
It was 5%. This aluminum alloy plate is further concentrated to 1
Current density 2A in 0 wt% nitric acid solution with liquid temperature 33 ° C
Anodization was performed using a direct current of / dm ² , washed with water and dried to obtain a lithographic printing plate support. This lithographic printing plate support was coated with the same photosensitive solution as in Example-1 and dried to form a photosensitive layer. At this time, the coating weight of the photosensitive layer after coating was 2.0 g / m ² . The lithographic printing plate thus obtained was a good printing plate with excellent stain performance.

Comparative Example-1 In the same manner as in Example-1,
After obtaining an aluminum alloy plate in which the area ratio of the recesses before the etching treatment is 28%, the aluminum alloy plate is subjected to a concentration of 7%.
A 1.0 g / m ² chemical etching treatment was performed with a sodium hydroxide aqueous solution having a wt% and a liquid temperature of 60 ° C. The area ratio of the recesses after etching was 56%. Further, the aluminum alloy plate has a concentration of 25 wt% and a liquid temperature of 60 ° C.
The surface hydroxide was removed by immersing in a sulfuric acid aqueous solution of, and washed with water. This aluminum alloy plate was anodized in the same manner as in Example-1 to form a lithographic printing plate support, and then a photosensitive layer similar to that in Example-1 was provided to prepare a lithographic printing plate. The lithographic printing plate thus obtained has poor stain performance,
It could not be used as a printing plate.

[0019]

As described above, according to the present invention, in the production of a lithographic printing plate support, transfer is performed by a transfer roller on an aluminum or aluminum alloy plate so that the area ratio of the recesses is 5 to 70%. After that, the post-treatment including chemical etching, electrochemical etching, or a combination of both is performed to adjust the area ratio of the recesses to 75.
Since it is configured to be higher than 100%, it is possible to obtain a support having no untransferred portion even when the rolling reduction of the transfer roller is low. Therefore, when a lithographic printing plate support obtained by the present invention is provided with a photosensitive layer to form a printing plate, a very good printing plate excellent in stain performance can be obtained. Further, the rolling reduction at the time of transfer can be set low, and since it is not necessary to repeat the transfer a plurality of times, the life of the transfer roller can be extended, and there is no dimensional error due to the stretching of the aluminum or aluminum alloy plate. can do.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view showing a transfer state of an aluminum plate surface by a transfer roller.

FIG. 2 is a partially enlarged cross-sectional view showing the surface of an aluminum plate after etching treatment.

FIG. 3 is a photograph of a fine pattern formed on an aluminum alloy plate by an etching treatment in Example-1. (Magnification 750 times)

[Explanation of reference numerals] 10 Aluminum plate 11 Recessed portion by transfer 12 Untransferred portion 13 Transfer roller 14 Convex portion on transfer roller 21 Transfer recessed portion after post-treatment

Claims (3)

[Claims] 1. A transfer roller is used to transfer the surface of an aluminum plate or an aluminum alloy plate so that the area ratio of independent recesses is 5 to 70%, and then post-treatment is performed by chemical etching. The area ratio of the recess is 7
A method for producing a lithographic printing plate support, which comprises increasing the amount to 5% or more. 2. The method for producing a lithographic printing plate support according to claim 1, wherein the post-treatment is electrochemical etching. 3. The method for producing a lithographic printing plate support according to claim 1, wherein the post-treatment is constituted by a combination of chemical etching and electrochemical etching.