JPS6132795A - Preparation of support for planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain the titled support capable of performing a graining process within a short time, forming a uniform sand mesh configuration, having good printing durability and making a non-printing area hard to stain, by chemically applying graining to the surface of an Al-plate by using an etching solution containing hydrochloric acid and unsaturated Al-chloride. CONSTITUTION:Chemical graining is applied to the surface of an Al-plate by using an etching solution containing 6-20wt% of hydrochloric acid and Al-chloride in an amount of 40-90% based on saturated concn. so as to pref. bring center line surface roughness to 0.3-1.3mum and anodic oxidation treatment is further applied thereto to obtain the desired support. For example, anodic oxidation treatment is performed by flowing a current in an aqueous solution of sulfuric acid or the like to form an anodic oxidation film and a photosensitive layer comprising O-naphthoquinone diazide compound may be further provided.

Description

[Detailed description of the invention]

[Field of the Invention] The present invention relates to a method for producing a support for a lithographic printing plate, and particularly to a method for producing a support for a lithographic printing plate, which includes a step of chemically graining the surface of an aluminum plate. It is. [Prior Art] Conventionally, aluminum plates have been widely used as supports for lithographic printing plates, but their surfaces are roughened to improve adhesion with the photosensitive layer and provide water retention to non-image areas. , it is necessary to carry out so-called graining, and this graining does not have a large effect on suitability in the plate-making process or on the printing durability when mounted on an offset printing machine after plate-making, so it is difficult to manufacture lithographic printing plates. This is an important process. As a specific means for such graining, a mechanical graining method using sandblasting, pole graining, wired C-in, brush graining using a nylon brush and abrasive/water slurry, etc., published by JP-A Shoj/-1. The chemical graining method of alkali etching a special aluminum alloy disclosed in Japanese Patent Application Laid-Open No. 30/30≠, or the chemical graining method of alkali etching a special aluminum alloy disclosed in Japanese Patent Application Laid-Open No. A chemical graining method of etching grade //θ0) with a saturated aqueous solution of an aluminum salt of a mineral acid, JP-A No. 23-23 and JP-A No. The electrochemical graining method described in Japanese Patent Publication No. 23;
A method is known that combines a mechanical graining method and an electrochemical graining method described in Japanese Patent No. 23.204L. However, one of the typical mechanical graining methods is
In the case of ball graining, the material of the pole,
There are many factors that require skill, such as the type of abrasive material and the adjustment of moisture during polishing, and it was impossible to perform the work continuously and it was necessary to finish each piece one by one. Also, the grain of wire-grained grains is non-uniform. Brush graining, on the other hand, is an improved version of these methods.It generally produces simple shallow grains, but has the drawback of low printing durability during printing, and rotates brush grains that remain on the surface. However, it also has the disadvantage that the grain becomes directional and the non-image areas are easily smudged. In addition, the chemical graining method disclosed in Japanese Patent Application Laid-Open No. 13017/13017 uses manganese as /, A~, 2.4-
It was difficult to obtain materials because aluminum alloy plates containing aluminum alloy sheets containing 1.5% had to be used, and the printing conditions caused stains on the printed matter, which was unfavorable in terms of quality. The aluminum plate chemically grained using a saturated aqueous solution of an aluminum salt of a mineral acid as an etching liquid, as disclosed in Publication No. 3//17, has the disadvantage that only a lithographic printing plate with low printing durability can be obtained. found. On the other hand, electrochemical graining methods can produce uniform grains with a higher average surface roughness than traditional mechanical graining methods such as graining, ball graining, and brush graining by selecting appropriate electrolytic conditions. can be created, but the drawback is that the conditions are extremely narrow. In other words, if various conditions such as the electrolyte composition, its temperature, and electrical conditions such as current density are kept constant, products with very little variation and uniform performance can be easily obtained, but if these electrolytic conditions are It was extremely difficult to adjust these conditions within an appropriate range. Moreover, if the surface of the cyfluminium plate is roughened using only the electrochemical graining method, it will consume a large amount of electricity, and the proportion of electricity in the manufacturing cost will be extremely large, making it economically uneconomical. There were also problems from this point of view. On the other hand, in the method of combining brush graining and electrochemical graining disclosed in JP-A-13-723.201L, there is no directionality of the grain, and the grain has a uniform outer roughness. However, if you use the same brush for brush graining for a long time, the brush will wear out and you will not be able to obtain a uniform quality product. When the brushes reach the point of wear, the operation must be stopped at that point, which poses a problem in continuous productivity. [Object of the Invention] Therefore, in view of the problems of the prior art as described above, the object of the present invention is to
Also, a support for a lithographic printing plate that can relatively easily obtain a uniform rough surface, has excellent long-term continuous productivity, is stain-free, and has excellent printing durability. An object of the present invention is to provide a manufacturing method. [Structure of the Invention] As a result of extensive research, the present inventors have decided to carry out chemical graining, in particular etching at least one side of a sialuminium plate using an aqueous solution containing hydrochloric acid and unsaturated aluminum chloride. It has been found that the above objectives are achieved. That is, the present invention provides a method for producing a support for a lithographic printing plate, which includes a step of chemically graining at least one side of an aluminum plate with an etching solution, wherein the etching solution is a hydrochloric acid solution containing 1% to 0% by weight. The manufacturing method is characterized in that the aqueous solution contains aluminum chloride in a range of 20% by weight based on the saturated concentration of aluminum chloride. Hereinafter, the present invention will be explained in detail step by step. The aluminum plate used in the present invention includes a pure aluminum plate and an aluminum alloy plate, and those manufactured by ordinary continuous casting are used. Various aluminum alloys can be used, such as silicon, copper,
An alloy of aluminum and metals such as manganese, magnesium, chromium, zinc, lead, bismuth, and nickel is used. These compositions contain some iron and titanium as well as other negligible impurities. Such an aluminum plate is chemically grained in accordance with the present invention, but if necessary, before that, it is cleaned to remove grease, rust, dirt, etc. adhering to the surface of the aluminum plate. May be processed. This cleaning treatment includes, for example, solvent degreasing using trichlene or the like, or alkaline etching degreasing using caustic soda or the like. Since smut is generated when degreasing is carried out by alkaline etching such as caustic soda, it is customary to further perform a desmutting treatment (for example, immersion in 10 to 30% nitric acid) to remove this. As described above, the optionally cleaned aluminum plate is chemically grained. The etching solution used in this chemical graining process is an aqueous solution containing hydrochloric acid and aluminum chloride. Hydrochloric acid is contained in the etching solution at f-20% by weight,
In particular, 10~/j heavy background% is particularly preferable. If the concentration of hydrochloric acid becomes lower than p% by weight, the graining speed becomes extremely slow, which is inappropriate. Further, when the concentration of hydrochloric acid becomes higher than 20% by weight, problems such as a severe corrosion reaction due to hydrochloric acid, a large amount of dissolved aluminum, a decrease in the thickness of the aluminum plate, and an increase in the load of drainage treatment occur. Aluminum chloride must be contained in a range of 40 to 90% by weight based on the saturated concentration, and preferably in a range of 70 to 90% by weight based on the saturated concentration. When the aluminum chloride concentration is lower than the saturation concentration by t/lo weight%, it is undesirable because the corrosion effect is severe and aluminum dissolution increases, and the center line surface roughness also reaches a high value (/ , jμ summary) is undesirable. On the other hand, if the concentration of aluminum chloride is higher than the saturated concentration by 20% by weight, the printing durability of the resulting lithographic printing plate will drop sharply, and the object of the present invention will not be achieved. By the way, Tokukai Akira! ! -3/ Publication No. 7 discloses a method of chemically graining the surface of an aluminum plate with a saturated aqueous solution of an aluminum salt of a mineral acid (for example, aluminum chloride). Although it is explained that it is important to use an etching solution containing a certain concentration, the inventors of the present invention have investigated the problem and found that an aluminum plate chemically grained with a saturated aqueous solution of aluminum chloride is suitable for the present invention. For a well-manufactured support,
The extremely unexpected result was that only a lithographic printing plate having a printing durability of at most 30% could be obtained. Therefore, the concentration of aluminum chloride contained in the etching solution used in the present invention is 40 to 90% higher than the saturation concentration.
The weight percentage is very important. In the present invention, the step of chemically etching with an etching solution as described above is preferably carried out so that the centerline average roughness of the surface to be treated of the aluminum plate is in the range of 0.3 to 3 μm. As the thickness decreases by 3 μm, the water retention capacity of the lithographic printing plate decreases.1.
As the thickness of 3μ increases, stains begin to appear in the non-image areas of the lithographic printing plate. The specific processing conditions for achieving such surface roughness include a temperature of 20 to IOθ°C and a processing time of 7.
It is advantageous to select from a range of 0 to 20 seconds, for example, when the etching solution is brought into contact with the aluminum plate, such as by spraying the etching solution onto the surface of the aluminum plate or by immersing the aluminum plate in the etching solution. You can also use offensive methods. Since smut occurs on the surface of the aluminum plate chemically textured in this way, it is preferable to perform a desmant treatment to remove this smut. Desmutting is carried out by contacting the aluminum surface with an aqueous acid or alkali solution, for example by spraying or dipping. Examples of acids include phosphoric acid, sulfuric acid, chromic acid, etc.; examples of alkalis include sodium hydroxide, potassium hydroxide, sodium triphosphate, potassium triphosphate, sodium aluminate, sodium metasilicate, sodium carbonate, etc. is included. Among these, the latter method using an aqueous alkali solution is particularly preferred because the processing speed is fast. These acids or alkalis θ,! ~Using an aqueous solution of 277~
Generally, the treatment is carried out at a liquid temperature of 10° C. for 7 to 300 seconds. If an alkaline aqueous solution is used, the surface of the aluminum plate will not dissolve and an undissolved residual liquid that will not dissolve in alkali will be formed on the surface. This insoluble residue is removed by treatment with a mixed acid containing a combination of the above acids. The aluminum plate treated as described above can be used as a support for lithographic printing plates either as it is or after being further treated to make it hydrophilic. is subsequently anodized. The anodic oxidation treatment can be performed by a method conventionally practiced in this field. Specifically, sulfuric acid, cynic acid,
When a direct or alternating current is passed through aluminum in an aqueous or non-aqueous solution containing chromic acid, oxalic acid, sulfamino acid, benzenesulfonic acid, etc. or a combination of two or more of these, an anodized film is formed on the surface of the aluminum support. I can do it. The processing conditions for anodic oxidation vary depending on the electrolyte used, so although it cannot be determined in general, the temperature of the electrolyte is /~♂Owt%, the solution temperature is ~70℃, and the current is Appropriate ranges are a density of O, S-6θ ampere/dm'', a voltage of 100 μm, and an electrolysis time of 30 seconds to 0 minutes. Among these anodizing treatments, British Patent No. 11.
≠/2, ・The method of anodizing at high current density in sulfuric acid used in the invention described in No. 76g and US Patent No. 3. ,! The method of anodic oxidation using phosphoric acid as an electrolytic bath, which is described in the specification of ls2/, is preferred. Anodized aluminum plates are further described in U.S. Patent 3. /
J? As described in the specifications of US Pat. ,
,/! ;31. ≠U.S. Patent No. 3.11 treated with polyvinylphosphonic acid as described in the specification of No.
．． 0. ．． ．． As stated in Specification No. 26 of
An undercoat layer of hydrophilic cellulose (eg, carboxymethyl cellulose, etc.) containing a water-soluble metal salt (eg, zinc acetate, etc.) can also be provided. On the planographic printing plate support according to the present invention, a conventionally known photosensitive layer is provided as a 28th plate photosensitive layer to obtain a photosensitive lithographic printing plate (hereinafter referred to as 28th plate). The lithographic printing plate obtained by plate-making this has excellent performance. The composition of the photosensitive layer includes (a) one consisting of a diazo resin and a binder, (b) one consisting of an o-naphthoquinonediazide compound, (C) one consisting of an azide compound and a binder, and (d) one consisting of an ethylenically unsaturated seven-dimensional compound. A photopolymerizable composition comprising a Zimmer 1 photopolymerization initiator and a polymer binder,
(e) Includes those made of photocrosslinkable polymers having a 10H=OH-00- group in the main chain or side chain of the polymer,
Details of these can be found in U.S. Patent No. 23g, t j A 0
It is explained in detail in the specification. Such a photosensitive layer may be applied to a support prepared according to the present invention in an amount of from about O0/ to about 79/r.
l, preferably 00j-≠f/rr? It is provided so that the coating amount is . [Effects of the Invention] According to the method for producing a lithographic printing plate support of the present invention, the chemical graining step can be carried out in a short time, and a uniform grain shape can be formed on the surface of an aluminum plate. There are advantages that can be achieved. The lithographic printing plate produced using the lithographic printing support produced according to the present invention has a better printing life than the conventional chemical graining method or mechanical graining method. The great effect of having power can be obtained. In addition, the printing plate using the method of the present invention has the same property as mechanical graining.
The results also showed that the non-print areas were less likely to get dirty. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that % in the examples indicates weight % unless otherwise specified. Example 1 Thickness 0. ．． 24tu aluminum plate (material JISA/
θ30) with 10% hydrochloric acid and aluminum chloride at a saturation concentration of gj% (approximately 20% of the total weight of the etching solution).
At 70°C in an aqueous solution containing
It was immersed and chemically grained to give it a μ-coat finish. Then, in a 10% aqueous sodium hydroxide solution at 50°C,
The sample was immersed for a second to remove the smut generated during the graining process, and then neutralized and washed with 10% nitric acid to remove any undissolved residue, followed by washing with water. Next, the amount of oxide film in 71% sulfuric acid aqueous solution is /,! After anodizing to give f/-, the support was washed with water and dried to prepare a support [/゛]. A photosensitive solution having the following composition was applied to the support thus obtained and dried to provide a photosensitive layer. The dry coating amount of the photosensitive layer is 1. It was f/- in the evening. Photosensitive solution The photosensitive lithographic printing plate thus prepared was placed at a distance of 7 m using a λKW metal halide lamp as a light source, and exposed through a positive transparent image for lIO seconds. The printing plate made in this way was printed in the usual manner.The results are shown in Section 1 below.
Shown in the table. Comparative Example 1 The procedure was exactly the same as in Example 1 except that an aqueous solution containing aluminum chloride at a saturated concentration was used. A support (A) was prepared. -Using this support, photosensitive layer coating, exposure,
The steps from development to gumming to printing were carried out in the same manner as in Example 1.The results are shown in Table 1 below. Comparative Example 2 An aluminum plate with a thickness of 0.211 m/m was
Bumstone Meshes - Mechanically grained aluminum with a rotating nylon pusher in a suspension of water.
Immersed at 0℃ for 60 seconds to remove abrasives, aluminum chips, etc. that were embedded into the aluminum surface during graining treatment and equalize the surface, then rinsed with running water, then neutralized with 20% nitric acid and rinsed with water. did. Next, in an aqueous it% sulfuric acid solution, anodization was performed so that the oxide film amount was /, J-t/, washed with water, dried to prepare a support (B), coated with an O photosensitive layer, exposed to light, and developed the gum. The process from drawing to printing was carried out in the same manner as in Example 1. The results are shown in Table 1 below. *○: No stains occur even if the printing conditions change. Δ: Staining occurs due to slight variations in printing conditions. From the results in Table 1, it can be seen that the support according to the present invention has superior performance in both stain resistance in non-image areas and printing durability compared to Comparative Examples 1 and 2. It is noteworthy that the support (A) chemically grained with an etching solution containing a saturated concentration has a significantly lower printing durability. Example 2 Aluminum plate with thickness Oo, 2≠
030) with 10% hydrochloric acid and aluminum chloride at a saturated concentration! % (approx. sX based on the total weight of etching solution)
) in an aqueous solution containing centerline surface roughness of O, SS at 70°C.
It was immersed and chemically grained so that it had a diameter of 10 μm, and then added to a 10% sodium hydroxide aqueous solution using the 90 method at 70°C at 10°C.
The smut generated by the above-mentioned graining process was removed by immersion for seconds, and the insoluble residue was removed by neutralizing with 20% nitric acid. 7. After anodizing to St/-, it was washed with water, immersed in a 2% aqueous sodium silicate solution at 70°C for 7 minutes, washed with water, and dried to prepare a support. A photosensitive solution having the following composition was applied to the support thus obtained and dried to provide a photosensitive layer. The coating amount of the photosensitive layer after drying was 0 fld. Photosensitive liquid (S-<μm hydroxyphenyl) methacrylate The photosensitive lithographic printing plate thus prepared was exposed to jKW from a distance of 7 m through a transparent negative film in a vacuum printing frame.
After exposure for 10 seconds using a metal noride lamp, the plate was developed with a developer having the composition shown below, and gummed with an aqueous gum arabic solution to prepare a lithographic printing plate. Developer The printing plate made in this manner was printed in the usual manner. The results are shown in Table 2 below. Comparative Example 3 Aluminum plate with a thickness of 0.247 m (material: 5h)
ioto') was mechanically grained using a rotating nylon brush in a suspension of ≠OO mesh bumstone-water.◎The grained aluminum was immersed in a 10% aqueous sodium hydroxide solution at 50°C for 60 seconds. The abrasives, aluminum chips, etc. embedded in the aluminum surface during the graining treatment were removed to equalize the surface, followed by washing with running water, followed by neutralization with 20% nitric acid and washing with water. Next, it was anodized in a 71% sulfuric acid aqueous solution so that the amount of oxide film was /, jf/-, washed with water, immersed in a 2% sodium silicate aqueous solution at 70°C for 1 minute, washed with water, dried, and supported. body

[0]
The steps from coating the photosensitive layer, exposing, developing, gumming to printing were carried out in exactly the same manner as in Example 2. The results are shown in Table 2 below. *○: No stains occur even if the printing conditions change. Δ: Smudges occur due to slight variations in printing conditions. From the results in the $2 table, it can be seen that the support according to the present invention has better performance than Comparative Example 3 in that the non-image areas are less stained. Example 3 Aluminum plate with a thickness of 0.2 m (material JISA103
0) was chemically sanded by immersion treatment in an aqueous solution containing 7θ% hydrochloric acid and aluminum chloride at rθ% relative to the saturated concentration at 6 degrees Celsius so that the center line surface roughness was 0.1μ. I made it stand out. Then 10% aqueous sodium hydroxide solution KjO
℃ for 70 seconds to remove the smut generated during the above-mentioned graining, and then neutralized and washed with 20X nitric acid to remove undissolved residue, followed by thorough washing with water. Next, it was immersed in a 4.5% sodium silicate aqueous solution at 70°C for 3Q seconds, washed with water,
After drying, a support (3) was prepared. A photosensitive liquid having the following composition was applied onto this support (3) and dried to provide a photosensitive layer. The dry coating amount of the photosensitive layer is /,! 1
It was /-. Photosensitive solution The photosensitive lithographic printing plate thus prepared was placed at a distance of 7 m using a λKW metal halide lamp as a light source, and exposed for 60 seconds through a positive transparency.
It was developed using a developer having the following composition (liquid temperature: 2j'O), and then gummed. Printing was carried out using this printing plate, and the number of printed sheets and the degree of staining in the non-image area were examined, and the results are shown in Table 3 below. Comparative Example 4 A support (D) was prepared in exactly the same manner as in Example 3, except that an aqueous solution containing 10X hydrochloric acid and saturated aluminum chloride was used as the etching solution for chemical graining. The steps of coating this support with a photosensitive layer, exposure, development, gumming, and printing were carried out in the same manner as in Example 3. The results are shown in Table 3 below. Table 3 * O: No staining even if printing conditions vary. From the results in Table 3, it can be seen that the support of the present invention has superior printing durability compared to that of the comparative example.

Claims (4)

[Claims] (1) In a method for producing a support for a lithographic printing plate, which includes a step of chemically graining the surface of an aluminum plate with an etching solution, the etching solution contains 6 to 20% by weight of hydrochloric acid and 4% The production method is characterized in that the aqueous solution contains ~90% by weight of aluminum chloride. (2) The manufacturing method according to claim 1, wherein the chemical graining step is performed so that the centerline surface roughness is 0.3 to 1.3 μm. (3) A method for producing a lithographic printing plate support including steps of chemically graining the surface of an aluminum plate with an etching solution and anodizing the surface, wherein the etching solution is
40-9 for 20% by weight hydrochloric acid and its saturation concentration
The manufacturing method is characterized in that the aqueous solution contains 0% by weight of aluminum chloride. (4) The manufacturing method according to claim 3, characterized in that the chemical graining step is carried out so that the centerline surface roughness is 0.3 to 1.3 μm.