JP2940995B2 - Manufacturing method of photosensitive lithographic printing plate - Google Patents

Description

The present invention relates to a method for producing a photosensitive lithographic printing plate, and more particularly, to an image area of a photosensitive lithographic printing plate using a photosensitive composition containing a diazonium salt. The present invention relates to a method for producing a photosensitive lithographic printing plate, in which the printing strength is enhanced by strengthening the adhesive strength of the lithographic printing plate, and the long-term storage stability is improved by preventing the occurrence of stains in the non-image area.

b. Conventional technology Conventionally, an aluminum plate has been widely used as a support for a lithographic printing plate, and when used, in order to improve the adhesion of a photosensitive film and to impart water retention to a non-image area, Generally, the surface is grained (also called polishing, etching, or roughening).

Examples of the method of graining an aluminum plate include a mechanical polishing method such as ball polishing and brush polishing, an electrolytic polishing method in which electrolytic polishing is performed in hydrochloric acid, nitric acid, or an electrolytic solution mainly containing these, a chemical etching method using a chemical, a dry polishing method. Alternatively, there is a wet honing method, etc.
Further, a method combining these methods is also known.

Today, after such graining is performed, anodizing treatment is performed to prevent scratches on the surface, increase printing durability, or prevent dirt.

c. Problems to be Solved by the Invention However, since the water retention (hydrophilicity), the adhesiveness of the photosensitive layer, the storage stability, and the like are insufficient with the anodic oxidation treatment alone, various post-treatments performed after the anodic oxidation treatment are performed. Has been proposed. For example, U.S. Patent No. 318146, JP-A-51-46206
Japanese Patent Application Laid-Open No. H11-163873 proposes a method of treating with an aqueous solution of sodium silicate without using an electric current or using an electric current. However, according to these methods, the adhesiveness of the photosensitive printing plate can be increased, but the storage stability is inferior, particularly weak to moisture,
There is a disadvantage that it gets dirty quickly.

Also, as a post-processing method to reduce the occurrence of dirt,
There is a method of thinly applying a water-soluble compound such as polyvinyl sulfonic acid, polyacrylic acid, polymethacrylic acid, a cellulose compound, and polyvinyl alcohol, but this method has a drawback that printing durability is extremely reduced.

d. Means for Solving the Problems The present invention has been made in view of such problems,
The present inventors performed graining treatment and anodic oxidation treatment, and once dried an aluminum plate treated with metal silicate, and then again treated with metal silicate at least once to obtain a photosensitive lithographic printing plate. It has been found that it is possible to prevent the non-image portion from being stained and to improve the storability without deteriorating the printing durability.

That is, the present invention is subjected to graining treatment and anodizing treatment, then treated with metal silicate, then dried,
It is another object of the present invention to provide a method for producing a photosensitive lithographic printing plate, comprising applying a photosensitive composition containing a diazonium salt to an aluminum plate which has been treated at least once with a metal silicate.

Hereinafter, the manufacturing method of the present invention will be described in the order of the steps.

As the aluminum plate, a plate made of pure aluminum or an aluminum alloy can be used.

In the method of the present invention, first, the pretreatment of the surface of the aluminum plate is performed to remove the rolling oil on the surface of the aluminum plate to expose a clean aluminum surface. As a pretreatment method, for example, there is a method such as cleaning with a solvent or a surfactant, or etching cleaning with an alkali agent.

Subsequently, graining is performed. The graining method is not particularly limited, for example, a ball polishing method, a brush polishing method, a sand blast polishing method, a mechanical polishing method such as a buff polishing method, or an electrochemical polishing method,
Alternatively, a chemical polishing method using a chemical, a method combining two or more of these various polishing methods, or the like can be used.

After such polishing (graining), the surface of the aluminum plate is chemically alkali-etched for the purpose of removing abrasives and removing aluminum polishing residues. As the alkaline agent, sodium hydroxide, potassium hydroxide,
There are sodium tertiary phosphate, potassium tertiary phosphate, sodium aluminate, sodium carbonate, sodium metasilicate, sodium orthosilicate and the like, and these can be used alone or as a mixture of two or more.

The alkali concentration of the alkali etchant is preferably 1 to 60% by weight, and the treatment is performed at a solution temperature of 30 to 100 ° C. for 2 to 60 seconds, and etching is performed at 1 to 10 kg / m ² . As a method of performing the etching, there are a method of immersing the aluminum plate in an etching bath, a method of applying an alkali solution by a spray or a nozzle, and a method of flowing a solution from a slit-shaped opening to perform etching.

After the above alkali etching, desmut with nitric acid, phosphoric acid, sulfuric acid, chromic acid or a mixed acid containing two or more of these acids, or simply wash with water, and in some cases, high-pressure water wash (3 kg / cm ² or more) To remove the smut.

Next, the aluminum plate is subjected to an anodic oxidation treatment in order to prevent scratches on the surface and to more firmly adhere the photosensitive layer.

As the anodizing treatment method, a conventionally known method can be used. For example, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, etc., or a mixed acid obtained by combining two or more of these as an electrolytic solution, a concentration of 1 to 70% by weight, a temperature of 5 to 60 ° C.,
Anodization is performed under the conditions of a current density of 1 to 50 A / dm ² and a voltage of 1 to 100 V for an electrolysis time of 5 seconds to 20 minutes. The thickness of the anodic oxide film is 0.1 to 10 g / m ² , more preferably 0.2 to 6 g / m ² .

The anodized aluminum plate is treated with metal silicate. As metal silicates, for example, JIS 1,2,3
No. sodium silicate, sodium metasilicate, sodium orthosilicate, potassium A silicate, 2K potassium silicate, etc., can be used, with a concentration of 0.5 to 50% by weight, a temperature of 20 to 100 ° C, and a treatment time of 1 to 60 seconds. Immersion or a shower method.

After being treated with a metal silicate, the aluminum plate is washed with water, once dried with warm air or the like, and further treated again with a metal silicate. This re-processing is performed at least once. Even if the treatment is performed after the drying of the aluminum plate, the stain at the time of printing is not prevented, and the preservability as a photosensitive printing plate is not improved. Although the reason for this is theoretically unknown, the effect is remarkably exhibited once the treatment is performed after drying.

The treatment with a metal silicate may be performed on a web-like aluminum plate, or may be performed after cutting into a sheet.

A conventionally known photosensitive composition containing a diazonium salt is applied to the aluminum support of the present invention thus obtained.

The application of the photosensitive composition is desirably performed four days or more after the above-described metal silicate treatment. When 4 days or more have passed, it is necessary to apply the photosensitive composition after treating again with the metal silicate.

As the diazonium salt, for example, a diazo resin typified by a condensate of an aromatic diazonium salt and an active carbonyl-containing compound (particularly formaldehyde) is used. As the aromatic diazonium salt, for example, 4-diazodiphenylamine, 4-diazo- 3-methyldiphenylamine, 4-diazo-3'-methyldiphenylamine, 4-
Examples thereof include diazo-4'-methoxydiphenylamine and 4-diazo-3-methoxydiphenylamine.

Most preferably, the diazo resin is used in the form of an organic salt or an inorganic salt. Examples of the compound which forms an organic salt by combining with the above diazo resin include, for example, benzenesulfonic acid, p-toluenesulfonic acid, 2,5-xylenesulfonic acid, linear or side chain type dodecylbenzenesulfonic acid (commonly called dodecyl) Henzensulfonic acid), 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid, methanyl yellow, 2-chlorotoluene-4-sulfonic acid, and their alkali metal salts, alkaline earth metal salts, ammonium salts and the like. Can be mentioned.

Examples of the compound that forms an inorganic salt by combining with the diazo resin include, for example, borofluoric acid, hexafluorophosphoric acid, phosphotungstic acid, thiocyanic acid, and alkali metal salts and ammonium salts thereof. Can be mentioned.

The above diazo resins can be used alone or in combination, and the content thereof is preferably about 5 to 30% by weight based on the total weight of the photosensitive layer.

To the photosensitive composition of the present invention, a lipophilic polymer or copolymer is added together with a diazonium salt. Examples of the lipophilic polymer (co) polymer include phenolic resin, substituted phenolic resin, polyhydroxystyrene, halogenated polyhydroxystyrene, copolymer of hydroxystyrene and acrylic compound, styrene-maleic anhydride copolymer , An acrylic resin, a modified acrylic copolymer, and the like.

Among them, a monomer having an alcoholic hydroxyl group and / or a monomer having an aromatic hydroxyl group, an acrylate ester and / or a methacrylic ester monomer, and a monomer having a carboxylic acid group, Copolymers each containing at least one kind are preferred.

Examples of the monomer having an alcoholic hydroxyl group include 2-bidoxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and N-
Hydroxyethyl (meth) acrylamide and the like can be mentioned.

Examples of the monomer having an aromatic hydroxyl group include N-
(4-hydroxyphenyl)-(meth) acrylamide, N- (2-hydroxyphenyl)-(meth) acrylamide, N- (4-hydroxynaphthyl)-(meth)
Examples include acrylamide, o-, m- or p-hydroxyphenyl (meth) acrylate, o-, m- or p-hydroxystyrene, and the like.

As the acrylate, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate,
Octyl acrylate, stearyl acrylate and the like can be mentioned.

Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and amino methacrylate.

Examples of the monomer having a carboxylic acid group include acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and mono (2-methacryloxyethyl) hexahydrophthalate.

Further, other monomers can be further copolymerized with the lipophilic polymer (co) polymer. Other monomers that can be copolymerized include, for example, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, and the like.

A dye or pigment can be added to the photosensitive composition for the purpose of coloring. As these dyes or pigments, dyes or pigments which are not eluted by the developing solution from the image portion (cured portion by irradiation with ultraviolet rays or the like) during development of the photosensitive layer are desirable.

Examples of the dye include basic oil dyes such as crystalli violet, malachite green, Victoria blue, methylene blue, ethyl violet, rhodamine B, and derivatives thereof. As a commercially available product of such a dye, Victoria Pure Blue BO
H (made by Hodogaya Chemical Co., Ltd.), Oil Blue # 603 (made by Orient Chemical Co., Ltd.), Permanent Blue # 47
(Manufactured by Daido Chemical Co., Ltd.).

Examples of the pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and indanthrene blue. Commercially available products include Neozapon Blue FLE (produced by Birdish Aniline Co., Ltd.), Oil Blue BOS (produced by Orient Chemical Co., Ltd.), and Spiron Blue GNH (produced by Hodogaya Chemical Co., Ltd.). is there.

In addition, a preservative may be added to the photosensitive composition. As a preservative, for example, citric acid, tartaric acid, lactic acid, 5-sulfosalicylic acid, oxalic acid, DL-malic acid,
2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid. Furthermore, a plasticizer or a surfactant may be added for the purpose of improving the coating property of the photosensitive composition or improving the inking property of the composition. Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, and di-n-
Octyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, diisononyl phthalate, ethyl phthalyl ethyl glycol, dimethyl isophthalate and the like can be mentioned.

Examples of the surfactant include sorbitan monooleate, sorbitan stearate, sorbitan monostearate, sorbitan sex oleate, sorbitan monolaurate, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl phenyl ether, and the like. Can be.

Examples of the organic solvent used when coating the photosensitive composition on a support include methanol, methylene chloride, ethyl acetate, tetrahydrofuran, N-N-dimethylformamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene. Glycol monomethyl ether and the like, and as one or a mixture of two or more of these, various coating machines (for example, a wheeler, a roll coater, a bar coater,
(An extrusion coater or the like), and applied onto the aluminum support of the present invention, and dried.

The photosensitive composition applied on the support is exposed to actinic rays such as ultraviolet rays, and is developed using a weakly alkaline aqueous solution as a developing solution, whereby the unexposed portions are removed and the exposed portions are obtained as an image. .

As a weak alkaline aqueous solution used as a developer,
For example, (1) a metal salt of a weak acid, for example, a metal salt such as a sodium salt, a lithium salt, and a potassium salt such as silicic acid, metasilicic acid, orthosilicic acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, hexametaphosphoric acid, carbonic acid, tartaric acid, and boric acid (2) ammonia and its derivatives such as alkylamines (eg, monomethyl, dimethyl, trimethyl,
An aqueous solution of an alkaline compound such as an amine compound such as monoethyl, diethyl, and triethyl) or an alkanolamine (for example, monoethanolamine, diethanolamine, triethanolamine, and diisopropanolamine) can be given.

An activator and / or a solvent may be added to the above weak alkaline aqueous solution. As the activator, an anionic surfactant or an amphoteric surfactant can be used.

As the solvent, benzyl alcohol, phenylethyl alcohol, phenyl cellosolve, butyl cellosolve and the like can be used.

e. Action The photosensitive lithographic printing plate obtained by the production method of the present invention is a photosensitive lithographic printing plate obtained by providing a photosensitive composition containing a diazonium salt on an anodized aluminum plate that has been treated with a metal silicate at least twice. Because it is a lithographic printing plate,
In addition to the printing durability, the non-image area is less stained and has excellent long-term storage properties.

Therefore, the printed matter obtained using this printing plate is
It is clear printed matter without stain.

f. Examples Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1 A web-like aluminum plate (material 1050) having a thickness of 0.24 mm and a width of 1000 mm was alkali-degreased, and the surface was polished with a nylon brush while applying a water suspension of permiston, and then thoroughly washed with water.

Then, 70 ° C, 20% caustic soda solution was poured over 5 seconds, the surface was etched at 3 g / m ^2, and then washed with running water,
Electropolishing in an electrolytic solution consisting of hydrochloric acid (35 g /), boric acid (20 g /) and aluminum ion (20 g /) at 25 ° C. at a current density of 25 A / dm ² for 6 seconds, washing with water, and then 70 ° C., 20%
The surface was etched by pouring a sodium hydroxide solution of No. 1 and washed with water.

Next, anodization was performed in a 10% aqueous sulfuric acid solution at 30 ° C. to form an oxide film of 2.0 g / m ² .

Next, after washing with water, it was immersed in an aqueous solution containing 5% of JIS No. 3 sodium silicate at 70 ° C. for 10 seconds, washed with water and dried (hereinafter, the aluminum plate obtained at this point is referred to as a substrate 1). In the next step, JIS No. 3 sodium silicate 5
% In a solution containing 70% for 10 seconds, washed with water and dried (hereinafter, this substrate is referred to as a substrate 2,
One day, one month, and six months later, the substrates treated with the same sodium silicate are referred to as substrates 3, 4, and 5, respectively).

On the day after the substrates 1 to 5 were made, a photosensitive composition having the following composition was applied to each substrate and dried.

The acrylic copolymer (1) was produced as follows.

Under a nitrogen stream, 0.3 g of azobisisobutyronitrile was added to 150 g of dioxane, the mixture was heated to 80 to 85 ° C., and a mixture having the following composition was dropped into the mixture with stirring.

After completion of the dropwise addition, stirring was continued for 5 hours, 150 g of dioxane was added, and the mixture was poured into water to precipitate a copolymer. The precipitate was redissolved in 2-methoxyethanol, dropped into water, purified, and dried in vacuo (70 ° C.) to obtain an acrylic copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured. The result was 260 CPS (25 ° C.).

Next, on the substrates 1 to 5 coated with the above photosensitive composition,
Negative film is vacuum adhered, and using 2KW high pressure mercury lamp,
After irradiating with ultraviolet rays at a distance of 1 m for 30 seconds, development was carried out using a developing solution having the following composition (developing solution temperature: 25 ° C.).

After washing with water, a desensitized gum solution (arabian gum 8 ° Baume solution) was thinly applied and dried to obtain each lithographic printing plate.

Each of these plates is set on an offset printing machine (KOR type printing machine manufactured by Heidelberg), and the ink roller is dropped without applying water to the plate surface, ink is attached to the entire image area and non-image area, and then the water bar is dropped. Then, the number of sheets until the ink in the non-image area was completely removed and a clean printed matter was obtained (referred to as the number of damaged sheets) was examined. The smaller the number of broke sheets, the better the less stain-resistant plate. At the same time, press life and storage stability were also examined. Table 1 shows the results.
Substrates 2, 3, 4, and 5 were obtained by the manufacturing method of the present invention (Example), and substrate 1 was obtained by a method not following the manufacturing method of the present invention (Comparative Example).

The storage stability is as follows.
Leave it in a humid atmosphere of 80 ° C and 80% humidity for several days, then make the image and non-image areas through the above-mentioned plate making process, apply this plate to a printing machine, and until the non-image areas begin to become soiled Was evaluated by examining the number of days.

From the results shown in Table 1, it can be seen that the photosensitive lithographic printing plate according to the present invention has a smaller number of waste sheets than the comparative example and is excellent in printing durability and storage stability.

Example 2 After a web-like aluminum plate (material 1050) having a thickness of 0.24 mm and a width of 1000 mm (material: 1050) was alkali-degreased, the surface was polished with a nylon brush while applying a water suspension of permiston, and then thoroughly washed with water. Next, a 20% caustic soda solution at 70 ° C. was poured for 5 seconds, the surface was etched, washed with running water, and anodized in a 10% sulfuric acid aqueous solution at 30 ° C. to form an oxide film of 1.8 g / m ² . Was formed. Next, after washing with water, an aqueous solution containing 5% of 2K potassium silicate is used at 70 ° C. and 10 ° C.
The substrate was immersed for 2 seconds, washed with water and dried (hereinafter, the aluminum plate obtained at this time is referred to as a substrate 6).

Further, in the next step, immersion treatment was continued at 70 ° C. for 10 seconds in a solution containing 5% of 2K potassium silicate, and the substrate was washed and dried (hereinafter, this substrate is referred to as substrate 7). Substrate 7
The sheet was cut into a sheet of 1000 mm × 1000 mm and subjected to the same potassium silicate treatment as described above the day before the application of the photosensitive composition (hereinafter, this substrate is referred to as substrate 8).

On the day after the substrates 6 to 8 were made, a photosensitive composition having the following composition was applied and dried.

The acrylic copolymer (2) was obtained by polymerization with the following composition in the same manner as the acrylic copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured. As a result, it was 300 CPS (25 ° C.).

Next, on the substrates 6 to 8 coated with the above-mentioned photosensitive composition,
Negative film is vacuum adhered, and using 2KW high pressure mercury lamp,
After irradiating with ultraviolet rays at a distance of 1 m for 30 seconds, development was performed with the same developer as used in Example 1 (developer temperature 25 ° C.). After washing with water, a desensitized gum solution (arabian gum 8 ° Baume solution) was thinly applied and dried to obtain each lithographic printing plate.

Each of these plates was examined on a printing press in the same manner as in Example 1 for the number of damaged sheets and the printing durability, and then left in a high-humidity atmosphere for several days to examine the storage stability. Table 2 shows the results. Substrates 7 and 8 are examples, and substrate 6 is a comparative example.

From the results in Table 2, it can be seen that the photosensitive lithographic printing plate according to the present invention has a smaller number of waste sheets than the comparative example and is excellent in printing durability and storage stability.

f. Effects of the Invention According to the production method of the present invention, it is possible to obtain a photosensitive lithographic printing plate having little stain in non-image areas, good printing durability in image areas, and excellent long-term storage stability. Can be.

Claims (1)

(57) [Claims] 1. A photosensitive composition containing a diazonium salt on an aluminum plate which has been subjected to graining treatment and anodizing treatment, then treated with a metal silicate, dried, and further treated at least once with a metal silicate. A method for producing a photosensitive lithographic printing plate, comprising applying a photosensitive composition.