JPS6330296A - Preparation of support for photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a planographic printing plate hardly generating contamination in a non- image part, generating no contamination in the non-image part of printed matter and free from lowering in plate wear, by a method wherein surface roughening treatment is applied to at least the single surface of an aluminum plate and anodic oxidation treatment is subsequently applied thereto and the treated surface is further treated with an acidic aqueous solution containing sulfur oxyacid to dissolve a part of an anodic oxidation film. CONSTITUTION:The salt containing the oxyacid radical of sulfur in an acidic aqueous solution may be a salt of any element but, more pref., said salt is a salt of a metal of Ia, IIa, IIIa and VIII Groups of the Periodic Table or ammonium salt. As oxyacid of sulfur, sulfuric acid, sulfurous acid, hyposulfurous acid, permonosulfuric acid and perdisulfuric acid are designated but the most pref. one is sulfuric acid. In order to prepare the acidic aqueous solution with pH3 or less, any acid having action dissolving an oxide film may be added and, for example, there are sulfuric acid, hydrochloric acid, nitric acid, oxalic acid and sulfamic acid etc. The dissolving quantity of the oxide film is pref. 1-30% by wt. of the total amount of the oxide film. A planographic printing plate obtained by exposing and developing a photosensitive planographic printing plate using the support thus obtained provides an easy discrimination between an image part and a non-image in a correction process and has high plate wear.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for producing a support for a photosensitive lithographic printing plate, and in particular to an aluminum plate whose anodic oxide film has been modified to improve staining in non-image areas. The present invention relates to a method for producing a support for a lithographic printing plate.

[Prior art]

Conventionally, lithographic printing plates include so-called PS plates in which a photosensitive composition is coated in a thin layer on an aluminum plate. The surface is roughened by an electrochemical method such as the electrolytic grain method or a combination of both methods, and the surface is made into a matte finish.Then, the surface is etched with an aqueous solution of acid or alkali, and then anodized. After the treatment, a hydrophilic treatment is performed as desired to obtain a support for a planographic printing plate, and a photosensitive layer is provided on this support to obtain a PS plate (photosensitive planographic printing plate). This PS
The plate is usually subjected to imagewise exposure, development, correction, and gumming steps to form a lithographic printing plate, which is then mounted on a printing press and printed.

However, the substances contained in the photosensitive layer irreversibly adsorb to the non-image areas of the lithographic printing plate obtained by imagewise exposure and development of the PS plate described above, contaminating the non-image areas. There have been problems in that it is difficult to distinguish between image areas and non-image areas, and that traces of correction remain clearly, resulting in an uneven plate surface, and if the degree of correction becomes severe, it becomes smudged, making it impossible to use it as a printing plate.

To improve this, conventionally, the surface of the aluminum support was anodized, as described in US Pat. No. 3,181°461.
A method of soaking hydrophilic cellulose containing water-soluble metal salts in an alkali metal silicate as described in U.S. Patent No. 3,860,426. Method of priming or British Patent No. 2.0
A method of undercoating with sodium arylsulfonate as described in No. 98.627 has been proposed.

By performing such treatment, it is possible to prevent the above-mentioned contamination of the non-image area and prevent the occurrence of "'stains'" on printed matter. The disadvantage was that it was accompanied by a new problem: a reduction of 50 to 80% of the case.

Conventionally, a method of providing a thin layer of trihydroxypenzole carboxylic acid on the surface of an anodized aluminum support as described in Japanese Patent Publication No. 44-6410, or a method described in Japanese Patent Publication No. 41-14337, Images can be imaged by applying a process such as a method of providing a thin layer of mellitic acid as described in Japanese Patent Publication No. 38-8907, or a method of providing a thin layer of phosphonic acid and its derivatives as described in Japanese Patent Publication No. 38-8907. Attempts have been made to improve the adhesion of the areas, but on the other hand, a new problem has arisen in that the stains in the non-image areas are significantly worse than in the case where the above-mentioned treatment is not performed. In particular, as the time (storage time) from the production of the PS plate to the plate-making process becomes longer, such problems tend to become more prominent.

Conventional lithographic printing plates also have the problem of stains because ink adhering to non-image areas is not removed quickly.

In this way, lithographic printing plates that do not cause contamination in non-image areas tend to have low stiffness durability, and lithographic printing plates that do not cause a decrease in printing durability tend to have significant contamination in non-image areas. It was very difficult to satisfy them at the same time.

[Purpose of the invention]

Therefore, an object of the present invention is to prevent contamination from occurring in non-image areas (
Another object of the present invention is to provide a support for a lithographic printing plate, which allows a lithographic printing plate to be obtained without staining of non-image areas of printed matter and without deterioration in printing durability.

[Structure of the invention]

The present inventors have made extensive studies to achieve the object stated in item 1, and as a result, have accomplished the present invention. The present invention provides aluminum laminated l,
After roughening at least one side of the plate and then anodizing it, a pH 3 solution containing a salt containing an oxygen radical of sulfur is applied.
Treat with the following acidic aqueous solution to remove 1% of the total weight of the anodized film.
This is a method for producing a support for a photosensitive lithographic printing plate, characterized in that a support for a photosensitive lithographic printing plate is dissolved in an amount of up to 30% by weight.

The salt containing a sulfur oxygen acid group in the acidic aqueous solution used in the present invention may be a salt of any element. More preferred are salts of metals in groups Ia, fla, lla, and ■ of the periodic table, or ammonium salts. Specifically, NH4, Li5B
e, Na, Mg, ΔII'XK.

Ca 1M n% F e , SCO% N r X
It may contain salts such as ZnzSr-, Ba, etc., or two or more of these salts.

Examples of the sulfur oxygen acid include sulfuric acid, sulfurous acid, hyposulfite, persulfuric acid, and peroxonipersulfuric acid, and the most preferred is sulfuric acid.

In order to obtain an acidic aqueous solution with a roughness of ρ113 or less, any acid may be added as long as it has the effect of dissolving the oxide film. Examples include sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, and sulfamic acid.

Further, a compound of these salts and acids that can produce ionic species equivalent to those in an aqueous solution state and can form an aqueous solution with a pH of 3 or less may be used. Examples of such compounds include hydrogen sulfates such as sodium hydrogen sulfate, potassium hydrogen sulfate, carunium hydrogen sulfate, and ammonium hydrogen sulfate. Further, these compounds may also contain the above-mentioned acids at the same time.

When treated with an aqueous solution containing only an acid without the above-mentioned salts, i.e., an aqueous solution of a sulfur oxygen acid, the ink adhering to the non-image area is replaced by dampening water. Therefore, only the non-image area can be easily contaminated.

The dissolved amount of the oxide film is preferably 1 to 30% by weight, preferably 5 to 20% by weight, based on the total amount of the oxide film.

The amount of dissolved anodic oxide film is measured by gravimetric method as shown in the following formula.

WA: Total anodic oxide film amount (g/m'), S
: sample area (m2), ml: sample weight before treatment, m2: sample weight after treatment.Hereinafter, the present invention will be explained in detail step by step.

The aluminum plate used in the present invention is a plate-shaped body made of pure aluminum containing aluminum as a main component or an aluminum alloy containing a trace amount of foreign atoms.

Such foreign atoms include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of these foreign atoms is generally 10% by weight or less. Aluminum suitable for the support of the present invention is pure aluminum, but since completely pure aluminum is difficult to produce due to smelting technology, it is preferable to use aluminum that does not contain foreign atoms as much as possible. As described above, the composition of the aluminum plate applied to the present invention is not specified.
Conventionally known and publicly used materials can be used as appropriate. The thickness of the aluminum plate used in the present invention is preferably about 0.1 mm to 0.5 mm. Before anodizing the aluminum plate, a surfactant, for example, is applied to remove rolling oil from the surface. Alternatively, degreasing treatment and graining treatment using an alkaline aqueous solution may be performed as desired.

Graining treatment methods include a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. As a method for mechanically roughening the surface, known methods such as ball polishing, plan polishing, blast polishing, puff polishing, etc. can be used.

Further, as an electrochemical surface roughening method, there is a method in which alternating current or direct current is used in a hydrochloric acid or nitric acid electrolyte. Furthermore, a method that combines both methods can also be used, as disclosed in Japanese Patent Application Laid-Open No. 54-63902.

The aluminum plate thus roughened is subjected to alkali etching treatment and neutralization treatment as required.

Any electrolyte that forms a porous oxide film can be used as the electrolyte used for anodizing aluminum plates, and generally sulfuric acid, phosphoric acid, acid-resistant, chromic acid, or mixed acids thereof are used. The electrolytes and their concentrations are determined as appropriate depending on the type of electrolyte. The processing conditions for anodic oxidation vary depending on the electrolyte used, so they cannot be specified, but generally the electrolyte concentration is 1 to 80% by weight, the solution temperature is 5 to 70°C, and the current density is 5.
A range of ~60 A/dm2, a voltage of 1 to 100 cm, and an electrolysis time of 10 seconds to 50 minutes are suitable.

The amount of the anodic oxide film is preferably 0.1 to 10 g/m', more preferably 1 to 6 g/m'.

The aluminum plate that has been anodized as described above is then washed with water and dried after dissolving 1 to 30% of its total weight in an acidic aqueous solution of p113 or less containing a salt containing an oxygen radical of sulfur. In this manner, the support for a photosensitive lithographic printing plate of the present invention is obtained.

The treatment of the anodized film with an acidic aqueous solution is carried out so that the dissolved amount of the oxide film becomes 1 to 30% by weight, preferably 5 to 20% by weight, based on the total weight of the film. When the amount of dissolved film is less than 1% by weight, the effect of preventing staining of the non-image area by the components of the photosensitive layer is hardly obtained, and when it is more than 30% by weight, the abrasion resistance of the non-image area is significantly reduced.

The treatment temperature can be arbitrarily selected from room temperature to boiling point, but in order to obtain the desired amount of oxide film dissolved in a short time, it is better to conduct the treatment at a higher temperature.

The salt containing a sulfur oxygen acid radical is contained in a concentration such that the concentration of ionic species that can be calculated as a sulfur oxygen acid radical in an aqueous solution is 0,001 mol/p or more, preferably 0,01 mol/p or more. The effect of the present invention cannot be obtained below this range. The concentration of the acid may be any concentration as long as the pH of the solution is 3 or less. If the pH exceeds 3, the amount of dissolved film will decrease significantly and the effects of the present invention will no longer be obtained.

The concentration, temperature, and treatment time range of the treatment solution cannot be determined unambiguously due to the type of treatment solution and restrictions from the treatment equipment, but in general, the concentration of salts containing sulfate groups is 0.
．． 001 mol/p ~ less than saturation concentration, processing temperature is 30°C ~
100° C. and treatment time ranges from 2 seconds to 5 minutes.

The treatment method may be any method as long as the acidic aqueous solution is brought into contact with the oxide film, such as a spray method or a dipping method.

After treatment with such an acidic aqueous solution,
An intermediate layer as described in Japanese Patent Application No. 149491 and Japanese Patent Application No. 158956/1986 can be provided.

Also, before or after providing this intermediate layer, US Pat.
It is also possible to treat with aqueous solutions of alkali metal silicates (e.g. sodium silicate), as described in No. 81.461.

A conventionally known photosensitive layer can be provided on the lithographic printing plate support thus obtained to obtain a photosensitive lithographic printing plate. The plate has excellent performance.

As the composition for the above photosensitive layer, any composition can be used as long as its solubility or swelling property in a developer changes before and after exposure. The typical ones will be explained below.

■ As a positive-acting photosensitive diazo compound,
Benzoquinone described in Publication No. 3-28403
Most preferred are esters of 1,2-diazide sulfonic acid chloride and polyhydroquinphenyl or esters of naphthoquinone-1,2-diazide sulfonic acid chloride and pyrogallol-acetone resin. Other comparatively suitable 0-quinone diazide compounds include benzoquinone diazide compounds described in U.S. Pat. No. 3,046,120 and U.S. Pat.
Diazide sulfonic acid chloride or naphthoquinone-1,2
- There are esters of diazide sulfonic acid chloride and phenol formaldehyde resin.

The 0-quinonediazide compound alone constitutes the photosensitive layer, but a resin soluble in alkaline water may be used in combination as a binder. Examples of resins soluble in alkaline water include novolac resins, such as phenol formaldehyde resin, cresol formaldehyde resin,
pt-7” tylphenol formaldehyde resin, phenol-modified xylene resin, phenol-modified xylene resin
Examples include mesitylene resin. Other useful alkaline water-soluble resins include polyhydroxystyrene, copolymers of polyhalogenated hydroxystyrenated (meth)acrylic acids and other vinyl compounds.

Further details of photosensitive layers comprising 0-quinonediazide compounds and their developers are described in U.S. Pat. No. 4,259,434.

■A photosensitive composition consisting of a diazo resin and a binder.

As a negative-acting photosensitive diazo compound, US Patent No. 2.
Diphenylamine, which is a reaction product of the diazonium salt disclosed in No. 063.631 and No. 2.667 and No. 415, and an organic condensing agent containing a reactive carbonyl group such as aldol or acecool. A condensation product of p-diazonium salt and formaldehyde (so-called photosensitive diazo resin) is preferably used. Other useful fused diazo compounds are U.S. Pat.
British Patent No. 1.312.925, British Patent No. 1.312.92
It is disclosed in each specification etc. of No. 6. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts and can therefore be coated from aqueous solution. Alternatively, these water-soluble diazo compounds can be converted into aromatic or aliphatic compounds having one or more phenolic hydroxyl groups, sulfonic acid groups, or both by the method disclosed in British Patent No. 1,280,885. It is also possible to use a substantially water-insoluble photosensitive diazo resin which is a reaction product of the reaction.

It can also be used as a reaction product with hexafluorophosphate or tetrafluoroborate as described in JP-A-56-121031.

In addition, diazo fat described in US Pat. No. 1,312,925 is also preferred.

Such diazo resins are used together with binders. Preferred binders are organic polymers having an acid value of 10 to 200, and specific examples include copolymers containing acrylic acid, methacrylic acid, crotonic acid, or maleic acid as an essential polymerization component, such as U.S. Pat. .123
．． 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, acrylonitrile or methacrylonitrile, ternary or acrylic acid or methacrylic acid and optionally further copolymerizable monomers as described in No. 276. Quaternary copolymers, acrylic acid or methacrylic acid, acrylic acid which has a hydroxyl group at the end and is esterified with a group containing a dicarboxylic acid ester residue as described in JP-A-53-120903. Or a copolymer of methacrylic acid and other copolymerizable monomers if necessary, a monomer having an aromatic hydroxyl group at the end as described in JP-A-54-98614 ( For example, N-(4-hydroxyphenyl)methacrylamide, etc.), acrylic acid or methacrylic acid, and if necessary, a copolymer with a small amount (or one) of other copolymerizable monomers, JP-A-56-4144 Copolymers of alkyl acrylates or methacrylates, acrylonitrile or methacrylonitrile, and unsaturated carboxylic acids as described in the above publication are included.Acidic polyvinyl alcohol m conductors and acidic cellulose derivatives are also useful.

■ A composition containing a compound that undergoes trimerization upon irradiation with actinic rays. For example, polyvinyl cinnamate, polyvinyl cinnamoyl ethyl ether, polyethylene cinnamate acrylate and its copolymers, polyethyl cinnamate methacrylate and its copolymers, polyparavinylphenyl cinnamate and its copolymers, polyvinyl benzal acetophenone and derivatives thereof, polyvinyl cinnamylidene acetate and derivatives thereof, allyl acrylate prepolymer and derivatives thereof Derivatives of polyester resins consisting of paraphenylene diacrylic acid and polyhydric alcohol, such as U.S. Pat. No. 3.030.2.08 There are compounds such as those described in the specification of No.

■ A so-called copolymerizable composition that causes a polymerization reaction when irradiated with active light. For example, compositions comprising an addition polymerizable unsaturated compound having two or more terminal ethylene groups and a photopolymerization initiator as described in U.S. Pat. There is.

The compound that trimerizes and the compound that undergoes a polymerization reaction upon irradiation with actinic rays may further contain a resin, a sensitizer, a thermal polymerization inhibitor, a dye, a plasticizer, etc. as a binder.

The photosensitive composition as described above is usually applied as a solution of water, an organic solvent, or a mixture thereof onto the support according to the present invention, and dried to prepare a photosensitive lithographic printing plate.

The coating amount of the photosensitive composition is generally about 0.1 to about 5.0
g/m' is suitable, about 0.5 to about 3.0 g
/m' is more preferable.

The photosensitive lithographic printing plate thus obtained is imagewise exposed using a light source containing actinic rays such as a carbon arc lamp, xenon lamp, mercury lamp, tungsten lamp, metal halide lamp, etc., and developed to obtain a lithographic printing plate.

〔Effect of the invention〕

The lithographic printing plate obtained by exposing and developing the photosensitive lithographic printing plate using the support obtained by carrying out the present invention has no contamination in the non-image area, and it is possible to distinguish between the image area and the non-image area in the correction process. It is easy and has high printing durability. In addition, no correction marks are produced, and therefore printed matter is not smeared due to correction marks.

Furthermore, the aluminum support obtained by carrying out the present invention has a whiter surface than the conventional one, has excellent plate inspection properties, and is also excellent in ink stain recovery ability.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "%" in the examples indicates "1% by weight" unless otherwise specified.

Example 1 The surface of a JIS1050 aluminum sheet was grained with a rotating nylon brush using a pumice water suspension as an abrasive. At this time, the surface roughness (center line average roughness) is 0.5
It was μ. After washing with water, add 10% caustic soda aqueous solution to 70°C.
The amount of aluminum dissolved is 6.
It was etched to give g/m'. After washing with water,
It was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize it, and then thoroughly washed with water. After that, in a 0.7% nitric acid aqueous solution, the anode special voltage 1
Electrolytic surface treatment was carried out for 20 seconds using a rectangular alternating waveform of 3 volts and a cathode special voltage of 6 volts (power supply waveform described in the example of JP-A-52-77702), and 20% sulfuric acid was heated at 50°C. After washing the surface by immersing it in a solution, it was washed with water.

Furthermore, the weight of the anodic oxide film was 3.0 in a 20% sulfuric acid aqueous solution.
Anodic oxidation treatment was performed using a direct current so that the thickness of the substrate was 10 g/m', washed with water, and dried to prepare a substrate (I).

This substrate (1) is dissolved in an aqueous solution (pfl 1.5 to 2.0) containing about 0.3% of IJ and about 0.2% of sulfuric acid.
The substrate was immersed at 90° C. for 10 seconds, washed with water, and dried to prepare a support [Δ]. The amount of dissolved anodic oxide film at this time is approximately 10% of the total film weight (approximately 0.3 g/
m'). The support created in this way (
A) A photosensitive solution with the following composition was applied, and the coating weight after drying was 2.5.
A photosensitive layer was provided by coating to give a ratio of g/m'.

The photosensitive lithographic printing plate thus prepared was exposed in a vacuum printing frame through a transparent positive film from a distance of 1 m using a 3KW metal halide lamp for 50 seconds, and the molar ratio of SiO2/Na2O was 1. .74
A 5.26% aqueous solution of sodium silicate (pH=12.
7).

After thoroughly washing with water and checking the non-image area for contamination, a part of the image area was erased with a commercially available erasing liquid, thoroughly washed with water, gummed, and printed in the usual manner. At this time, the occurrence of stains on the erased area and the printing durability were investigated. Furthermore, after applying ink to the entire surface of the lithographic printing plate, the number of prints until a clean print with no stains in the non-image area is obtained when printing is started using the usual procedure (hereinafter referred to as ink stain recovery ability) ) was investigated.

The above results are shown in Table 1.

[Comparative Example 1] A photosensitive layer was provided in the same manner as in Example 1 without performing acidic aqueous solution treatment on the substrate CI of Example 1, and printing was performed in the same manner as in Example 1.
I did the same thing.

The results are shown in Table 1.

[Example 2] The substrate [■] of Example 1 was treated with about 0.5% sodium hydrogen sulfate.
The anodized film was immersed in an aqueous solution (pit 1.5 to 2.0) at 90°C until 10% of the total weight of the film was dissolved (processing time 10 seconds), washed with water, dried, A support [B] was prepared. The steps from coating the photosensitive layer to printing were carried out in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 2] The substrate of Example 1 (1'l) was mixed with about 0.01% NaOH (p
H10-11) The anodized film was immersed at 90°C in an aqueous solution containing the solution until 10% of the total weight of the film was dissolved,
It was washed with water and dried to prepare a support [■]. The steps from coating the photosensitive layer to printing were carried out in the same manner as in Example 1.

The results are shown in Table 1.

[Example 3] The substrate [■] of Example 1 was treated with sulfuric acid (IJum) of about 0.3
%, an aqueous solution containing about 0.2% hydrochloric acid (pH 1.0-1.5
) at 90°C until 10% of the total weight of the film is dissolved, washed with water, dried, and prepared as a support [C].
It was created. The steps from coating the photosensitive layer to printing were carried out in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 3] The substrate [■] of Example 1 was dissolved in an aqueous solution containing 0.5% sulfuric acid (
The substrate was immersed at 90° C. at a pH of 1.0 or below so that about 10% of the total weight of the anodized film was dissolved, washed with water, and dried to prepare a support [■]. The steps from coating the photosensitive layer to printing were carried out in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 4] The substrate [■] of Example 1 was diluted with about 0.5 sodium hydrogen sulfate.
% (flH 1.5 to 2.0) was adjusted to pH 4.0 with caustic soda, and as in Example 1, 9.
Although immersion treatment was performed at 0° C. for 10 seconds, the anodic oxide film did not dissolve.

JP-A-63-3029G(8) -G)-JJ Lo From the results in Table 1, the printing durability of the support prepared by the method of the present invention is 1 degree lower than that of the comparative example. It can be seen that the contamination in non-image areas and the contamination of correction marks have been improved. Furthermore, it can be seen that the support according to the present invention has excellent ink stain recovery ability.

Further, although these results are for the case of a treatment liquid containing sulfate, similar effects were obtained in the case of sulfite or persulfate.

Further, similar good results were obtained with this support not only in the positive type photosensitive layer but also in the negative type photosensitive layer.

Claims (1)

[Claims] At least one side of the aluminum plate is roughened and then anodized, and then treated with an acidic aqueous solution containing a salt containing an oxygen radical of sulfur and having a pH of 3 or less to form an anodized film of 1 to 10% of the total weight of the aluminum plate. A method for producing a support for a photosensitive lithographic printing plate, characterized in that it dissolves 30% by weight.