JPH10171104A - Production of base for positive type photosensitive planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a base for a positive type photosensitive planographic printing plate capable of yielding the positive type photosensitive planographic printing plate which simultaneously satisfies a stop staining property, a photoreceptor remaining characteristic, erasability, fringe staining, sludge and printing resistance. SOLUTION: In the process for producing the positive type photosensitive planographic printing plate formed by disposing a photosensitive layer on the aluminum base subjected to an electrolytic surface roughening treatment in an aq. hydrochloric acid soln., an anodic oxidation treatment and a hydrophilicity impartation treatment in this order, the hydrophilicity impartation treatment is executed by an aq. carboxylate soln. In addition, the hydrophilicity impartation treatment by an alkaline metal silicate soln. of 3.0 to 4.0 in the molar ratio of SiO2 /M2 O (M denotes an alkaline metal) and 0.05 to 0.5wt.% in the concn. of the alkaline metal silicate before or after the execution of the hydrophilicity impartation treatment. The hydrophilicity impartation treatment by an aq. hydrophilic high-polymer soln. is otherwise executed after the hydrophilicity impartation treatment by the aq. carboxylic acid soln. described 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 support for a photosensitive lithographic printing plate, and more particularly to a positive type excellent in stop stain, photoreceptor residual property, erasability, fringe stain, sludge, and printing durability. The present invention relates to a method for producing a support for a positive photosensitive lithographic printing plate capable of obtaining a photosensitive lithographic printing plate.

[0002]

2. Description of the Related Art Conventionally, a support used for a photosensitive lithographic printing plate is required to be excellent in hydrophilicity, water retention and adhesion to a photosensitive layer from the viewpoint of printability. Usually, an aluminum plate subjected to a surface roughening treatment called graining is used. The surface roughening process
Mechanical surface roughening methods such as ball polishing, brush polishing, blast polishing, buff polishing, and honing polishing, and electrochemically roughening the surface of the support by AC or DC in an acidic electrolyte such as hydrochloric acid or nitric acid Chemical conversion methods are known.

An aluminum plate grained by such a method is inferior in printability and abrasion resistance as it is, and is then subjected to an anodic oxidation treatment to form an oxide film.
Further, for the purpose of satisfying the developing performance, plate making performance and printing performance, the anodized film is subjected to a hydrophilic treatment. U.S. Pat. Nos. 2,714,066 and 3,
No. 181,461, No. 3,280,734, No. 3,9
No. 02,734, an alkali metal silicate (for example, sodium silicate aqueous solution) method.
Potassium fluoride zirconate disclosed in U.S. Patent No. 6,276,868;
No. 3,461,4,689,272, a method of treating with polyvinyl sulfonic acid.
JP-A-21126 discloses a method for providing an undercoat layer comprising a hydrophilic resin and a water-soluble salt, JP-A-64-14090 discloses a method for providing an undercoat layer comprising a carboxylate, No. 63-130391, which comprises at least one selected from inorganic acid salts and organic acid salts of a compound having at least one amino group and at least one group selected from a carboxyl group and a sulfo group. A method of providing a hydrophilic layer, a method of providing a hydrophilic layer containing at least one amino group and a phosphon group or a salt of a phosphon group disclosed in JP-A-63-165183,
Although many proposals have been made, in any case, after the printing press has been stopped for a while for registration or a break during printing, fine dot-like stains (hereinafter referred to as stop stains) that occur when printing is resumed, and the photosensitive member remains. , Erasability, fringe stain, sludge, printing durability, etc. could not be satisfied at the same time.

Further, in the case of a rough surface, US Pat.
No. 1,229 specifies the cumulative frequency distribution of the pit diameter and the center line average roughness, US Pat. No. 3,861,917 specifies the depth of the rough surface, and Canadian Patent No. 955,449 describes the peak of the rough surface. Height and diameter, German Patent No. 1,813,4
No. 43 specifies the height difference of a rough surface.
No. 94 specifies an average depth, and JP-A-5-24376 proposes a specification of a pit diameter and a maximum depth in a direction perpendicular to the diameter. However, even with these shapes, stop dirt and sludge can be improved. Was inadequate.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a positive type which simultaneously satisfies stop stain property, photoreceptor remaining property, erasability, fringe stain, sludge, and printing durability. It is an object of the present invention to provide a method for producing a support for a positive type lithographic printing plate capable of obtaining a photosensitive lithographic printing plate.

[0006]

The above object of the present invention is achieved by the following means.

Production of a positive photosensitive lithographic printing plate support comprising a photosensitive layer provided on an aluminum support which has been subjected to electrolytic surface roughening treatment, anodic oxidation treatment and hydrophilic treatment in an aqueous hydrochloric acid solution in this order. In the method, before or after the hydrophilization treatment is performed with an aqueous solution of a carboxylate, the hydrophilization treatment is performed using SiO 2.
The molar ratio of ₂ / M ₂ O (M represents an alkali metal) is 3.0
-4.0, alkali metal silicate concentration 0.05-0.4.
A method for producing a support for a positive photosensitive lithographic printing plate, characterized by performing a hydrophilization treatment with an aqueous solution of an alkali metal silicate of 5 wt%.

Production of a positive type photosensitive lithographic printing plate support comprising a photosensitive layer provided on an aluminum support which has been subjected to electrolytic surface roughening treatment, anodic oxidation treatment and hydrophilic treatment in an aqueous hydrochloric acid solution in this order. The method for producing a support of a positive photosensitive lithographic printing plate, wherein the hydrophilic treatment is performed by a hydrophilic treatment with an aqueous solution of a carboxylate, followed by a hydrophilic treatment with an aqueous solution of a hydrophilic polymer.

Hereinafter, the present invention will be described in detail.

The aluminum support used in the present invention includes a support made of pure aluminum and an aluminum alloy. Various aluminum alloys can be used, for example, silicon, copper, manganese, magnesium,
An alloy of aluminum with a metal such as chromium, zinc, lead, bismuth, nickel, titanium, sodium and iron is used. The composition of the aluminum support used in the present invention is not particularly limited, and any known or publicly available one can be used. A preferred material is JIS A10
50 and 1100.

The aluminum support is preferably subjected to a degreasing treatment to remove rolling oil on the aluminum surface prior to roughening. As the degreasing treatment, trichlene,
A degreasing treatment using a solvent such as a thinner, an emulsion degreasing treatment using an emulsion of kerosene, triethanol, or the like is used. In the degreasing treatment, an aqueous solution of an alkali such as caustic soda can be used. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed by the above degreasing treatment alone can also be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is formed on the surface of the support. In this case, the smut is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof and desmutted. Preferably, a treatment is applied.

Next, the surface roughening treatment in the production of the photosensitive lithographic printing plate support of the present invention will be described.

In the present invention, it is assumed that electrolytic surface roughening treatment in an aqueous hydrochloric acid solution is a precondition.

The electrolysis conditions in the aqueous hydrochloric acid solution are not particularly limited. For example, the concentration of hydrochloric acid is 1 to 10% by weight, and the liquid temperature is 5 to 5%.
0 ° C., current density 20 to 100 A / dm ² , electric quantity 100
It is preferable to carry out in the range of -800 C / dm ² .

After performing the electrolytic surface roughening treatment with the hydrochloric acid aqueous solution, a chemical treatment with an acid or a base is performed. The purpose is to remove smut and the like remaining on the surface formed by the electrolytic surface roughening treatment.

Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid,
Phosphoric acid, nitric acid, hydrochloric acid, etc. are included, and as the base, for example,
Sodium hydroxide, potassium hydroxide and the like are included. Among these, it is preferable to use an aqueous alkali solution. When the above treatment is performed with an aqueous alkali solution, smut is formed on the surface of the support. In this case, the substrate is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof to be desmutted. It is preferable to apply.

The anodic oxidation can be performed by a method conventionally used in this field. Specifically, sulfuric acid, phosphoric acid,
Chromic acid, oxalic acid, sulfamic acid or their two
A combination of the above species is used, and a direct current is applied to aluminum in an aqueous solution to form an anodized film on the surface of the aluminum support. Anodizing conditions vary depending on the electrolytic solution used, but generally, the concentration of the electrolytic solution is 1 to 50 watts.
t%, liquid temperature 5 to 50 ° C., current density ^{2 to} 10 A / dm ² ,
Voltage 5 to 50 V, electrolysis time 1 to 100 seconds in a range of 0.5
It is appropriate to set the amount of the oxide film to ５5 g / m ² . In addition, a technique of using an electrolytic solution of sulfuric acid or phosphoric acid in these anodizing treatments is generally used.

Next, the hydrophilizing treatment performed on the aluminum anodic oxide film, which is a feature of the present invention, will be described.

In order to achieve the effects of the present invention, the molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) is 3.0 to 4 before or after the hydrophilization treatment with an aqueous carboxylate solution. 0.0, a hydrophilization treatment with an aqueous metal silicate solution having an alkali metal silicate concentration of 0.05 to 0.5 wt%, a hydrophilization treatment with a carboxylate aqueous solution, and then a hydrophilic polymer It is necessary to perform a hydrophilization treatment with an aqueous solution.

The carboxylate used in the hydrophilization treatment of the present invention is a compound having the following structural formulas (I) to (III).

(I) (R ₁ COO) _n Z (II) R ₂ COO-Z-OOCR ₃ or (III) R ₄ (COO) ₂ Z where R ₁ , R ₂ and R ₃ are the same or different. Represents hydrogen or an aliphatic group having 1 to 10 carbon atoms, an alicyclic or aromatic group, and R ₄ has 0 to 10 carbon atoms.
Aliphatic groups, alicyclic or aromatic groups.

Z is a hydrogen ion, NH ₄ ion, Group Ia metal ion or monovalent or divalent ion selected from Group IIa, VIIa, VIII, IIb or IVb metal. And n represents the integer of 1 or 2.

Preferably, it is a hydrophilic compound containing at least one compound having the following structural formula.

[0024]

Embedded image

However, R ₁ , R ₂ and R ₃ are each the same or different hydrogen or an aliphatic, alicyclic or aromatic group having 1 to 10 carbon atoms.

R ₄ is a divalent group derived from an aliphatic, alicyclic or aromatic compound, and X ₁ is selected from NH ₄ ions or alkali metal ions (provided that X ₂ and X ₃ are simultaneously And cannot be hydrogen), and Y is group IIa, VIIa
It is a divalent metal ion selected from metals of Group IV, VII, IIb or IVb.

Among these compounds, useful compounds used in the present invention include ammonium formate, sodium formate,
Potassium formate, lithium formate, calcium formate, barium formate, magnesium formate, zinc formate, manganese formate,
Nickel formate, strontium formate, lead formate, ammonium acetate, sodium acetate, potassium acetate, lithium acetate, calcium acetate, barium acetate, magnesium acetate, zinc acetate, nickel acetate, strontium acetate, lead acetate, ammonium propionate, sodium propionate, Potassium propionate, lithium propionate,
Calcium propionate, barium propionate, magnesium propionate, zinc propionate, manganese propionate, nickel propionate, strontium propionate, lead propionate, ammonium butyrate, sodium butyrate, potassium butyrate, lithium butyrate, calcium butyrate, barium butyrate, Magnesium butyrate, zinc butyrate, manganese butyrate, nickel butyrate, strontium butyrate, lead butyrate, ammonium oxalate, sodium oxalate, potassium oxalate, lithium oxalate, calcium oxalate, barium oxalate, magnesium oxalate, zinc oxalate, manganese oxalate, nickel oxalate, strontium oxalate , Lead oxalate, ammonium malonate, sodium malonate, potassium malonate, lithium malonate, barium malonate, calcium malonate, nickel malonate, Magnesium phosphate, manganese malonate, zinc malonate, strontium malonate, lead malonate, ammonium succinate, sodium succinate, potassium succinate, lithium succinate, calcium succinate, barium succinate, magnesium succinate, succinic acid Zinc, manganese succinate, nickel succinate, strontium succinate, lead succinate, ammonium glutarate, sodium glutarate, potassium glutarate, lithium glutarate, calcium glutarate, barium glutarate, magnesium glutarate, zinc glutarate, glutar Manganese acid, nickel glutarate, strontium glutarate, lead glutarate, ammonium phthalate,
Examples include sodium phthalate, potassium phthalate, lithium phthalate, calcium phthalate, barium phthalate, magnesium phthalate, zinc phthalate, manganese phthalate, nickel phthalate, strontium phthalate, lead phthalate, and the like.

The above hydrophilic compound is added at a concentration of 0.0
It is used for immersion of an aluminum support as an aqueous solution having a temperature of 30 to 95 ° C. at a temperature of 01 to 10% by weight. Immersion time is 1-6
A range of 0 seconds is appropriate.

Before or after the hydrophilization treatment of the carboxylate aqueous solution, the molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) is 3.0 to 4.0, and the concentration of the alkali metal silicate is The immersion conditions for the hydrophilization treatment with the aqueous alkali metal silicate solution of 0.05 to 0.5 wt% are, for example, the following: an alkali metal silicate aqueous solution having a pH of 9 to 12 at 25 ° C. For 1 to 90 seconds. As the alkali metal silicate, sodium silicate, potassium silicate and the like are used. Also, a small amount of hydroxide may be added to adjust the pH.

The hydrophilic polymer used for the hydrophilic treatment with the aqueous hydrophilic polymer solution after the hydrophilic treatment with the aqueous carboxylate solution is dissolved in water or a solvent mainly composed of water,
In addition, it is selected from those having a film forming ability.

The hydrophilic polymer compound used in the present invention includes acrylic acid copolymers such as polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyhydroxyethyl acrylate, and polyvinylpyrrolidone; polyethyleneimine, diacryldimethylaluminum chloride, polyvinyl Maleic acid copolymers such as imidazoline and polyalkylaminoethyl acrylate; polyethylene glycol polyoxyethylene, polypropylene glycol, ethylenediamine, hexaethylenediamine, polyurethane resin, polyhydroxymethylurea, polyhydroxymethylmelamine resin, and modified starch;
Water-soluble polymers such as dextrin, CMC (carboxymethylcellulose), CEC (carboxyethylcellulose), hydroxyethylcellulose, guar gum, tragacanth gum, gum arabic, xanthan gum, sodium alginate, and gelatin.

An aqueous solution containing 1% by weight or less, preferably 0.001 to 0.1% by weight of the above polymer is preferably p
It is used for immersion of the support under the conditions of H9 or less, a temperature of 30 to 95 ° C, and an immersion time of 1 to 90 seconds.

As the photosensitive liquid used in the present invention, known photosensitive liquids for positive planographic printing plates can be used.

[0034]

EXAMPLES The effects of the present invention will now be illustrated by examples.

Example 1 An aluminum plate (material: 1050, tempered H16) having a thickness of 0.3 mm was immersed in a 10% aqueous sodium hydroxide solution maintained at 85 ° C., subjected to a degreasing treatment for 30 seconds, and then washed with water. did. The degreased aluminum plate was immersed in a 10% sulfuric acid aqueous solution maintained at 25 ° C. for 1 minute, subjected to desmut treatment, and washed with water. Then, the aluminum plate was added 1.0%
In hydrochloric acid aqueous solution at a temperature of 30 ° C. and a current density of 60 A
/ Dm ² and 50 Hz sine wave AC current
Electrolytic surface roughening was performed for seconds. Then, 10% kept at 60 ° C
Immerse in sodium hydroxide aqueous solution for 10 seconds, then
Immersed in a 10% sulfuric acid aqueous solution maintained at 5 ° C. for 20 seconds,
After the desmut treatment, it was washed with water. Subsequently, an anodic oxidation treatment was performed in a 20% aqueous sulfuric acid solution at a temperature of 35 ° C. and a current density of 3 A / dm ² for 60 seconds. After that, concentration 0.05w
The sample was immersed in an aqueous solution of sodium oxalate at a temperature of 95% for 15 seconds to perform a first hydrophilic treatment. After rinsing with running water for 10 seconds, it is immersed for 30 seconds in an aqueous solution having a concentration of 0.2 wt% and a temperature of 30 ° C. for 30 seconds using sodium silicate having a molar ratio of SiO ₂ / Na ₂ O of 3.7 to form a second hydrophilic treatment. Processing was performed. 1
After washing with water for 0 second and drying at 80 ° C. for 5 minutes, aluminum support 1 was obtained.

Next, a photosensitive composition coating solution having the following composition was applied using a wire bar and dried at 80 ° C. for 2 minutes to obtain a photosensitive lithographic printing plate. At this time, the photosensitive composition coating solution was adjusted to have a dry weight of 2.0 g / m ² .

Novolak resin (phenol / m-cresol / p-cresol molar ratio: 10/54/36, Mw: 4000) 6.70 g pyrogallol acetone resin (Mw: 3000) and o-naphthoquinonediazide-5-sulfonyl chloride 1.50 g Polyethylene glycol # 2000 0.20 g Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Co., Ltd.) 0.08 g 2,4-bis (trichloromethyl) -6- (p- Methoxystyryl) -S-triazine 0.15 g FC-430 (manufactured by Sumitomo 3M Ltd.) 0.03 g cis-1,2-cyclohexanedicarboxylic acid 0.02 g methylcellosolve 100 ml The obtained photosensitive lithographic printing plate was 80 cm × Cut to 60cm, 4kW metal halide light as light source Using a pump
Exposure was performed by irradiating at 8 mW / cm ² for 60 seconds. The exposed photosensitive lithographic printing plate was diluted 6 times with a commercially available developer SDR-1 (manufactured by Konica Corporation).
Development was performed at a development temperature of 30 ° C. for a development time of 40 seconds.

For the positive type lithographic printing plate obtained using the support 1, stop stain property, photoreceptor remaining property,
Erasability, fringe stain, sludge, and printing durability were evaluated.

(Stop smearing property) Printing was performed under the same conditions as in the evaluation of the printing durability. When the 5000 sheets had been printed, the printing press was stopped once, allowed to stand for 1 hour, and then started printing. Was evaluated by the number within 100 cm ² .

(Photoreceptor Remaining Property) After the development processing, the support was evaluated as follows.

：: No photoconductor is detected (absorbance difference with respect to reference in UV measurement is 0.006 or less) Δ: Slight photoconductor is detected (absorbance difference with reference in UV measurement is less than 0.015) ×: The photoreceptor is clearly detected (absorbance difference with respect to the reference in UV measurement is 0.015 or more). (Erasing property) In the erasing operation of applying the correcting liquid to the image area and washing the correcting liquid with water after a lapse of a certain time, When the elapsed time was changed from 10 seconds to 60 seconds in increments of 10 seconds, the number of seconds required to complete the erasure of the image area was measured, and evaluated according to the following criteria.

A: within 10 seconds B: more than 10 seconds and within 20 seconds C: more than 20 seconds and within 30 seconds D: more than 30 seconds (fringe-like dirt) It was applied, left for 30 seconds, 5 minutes, 10 minutes, and 15 minutes, rinsed with water, and stains around the erased portion were determined using a loupe according to the following criteria.

：: No fringe-like stains are observed. Δ: Fringe-like stains are observed using a loupe. X: Fringe-like stains are visually observed. (Sludge) 10 m ² of 1 liter of developer The aluminum support was developed, and the state of scum generated in the developer was determined as follows.

：: No scum was generated at all △: Scum was slightly generated ×: Scum was generated (printing durability) The obtained lithographic printing plate was printed on a printing machine (Mitsubishi Heavy Industries, Ltd.).
Coated paper, dampening solution (etch solution SG-51, Tokyo Ink Co., Ltd., concentration 1.5)
%), Ink (High Plus M Red, manufactured by Toyo Ink Manufacturing Co., Ltd.)
And printing was performed until an ink deposition defect appeared on the image portion of the printed matter or ink adhered to the non-image portion, and the number of printed sheets at that time was evaluated as printing durability.

Table 1 shows the evaluation results.

Example 2 In the first hydrophilization treatment, a concentration of 0.1 wt% and 90 ° C.
Support 2 was obtained in the same manner as in Example 1 except that the sample was immersed in an aqueous nickel acetate solution for 15 seconds.

The positive type lithographic printing plate obtained using the support 2 was examined for stop stain property, photoreceptor residual property, erasability, fringe stain property, sludge, and printing durability by the method described in Example 1. The results shown in Table 1 were obtained.

Example 3 A support 3 was obtained in the same manner as in Example 1 except that in the hydrophilization treatment, the hydrophilization treatment with sodium silicate was performed after the hydrophilization treatment with sodium silicate.

The positive lithographic printing plate obtained by using the support 3 was evaluated by the evaluation method described in Example 1 for stopping stain resistance,
When the photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability were examined, the results shown in Table 1 were obtained.

Comparative Example 1 In the second hydrophilization treatment, the SiO ₂ / M ₂ O ratio was 2.5,
A support 4 was obtained in the same manner as in Example 1 except that an aqueous solution of sodium silicate having a concentration of 1.5 wt% was used. The positive lithographic printing plate obtained using the support 4 was evaluated for stop smearing property, photoreceptor remaining property, erasability, and the like by the evaluation method described in Example 1.
When the fringe stain property, sludge, and printing durability were examined, the results shown in Table 1 were obtained.

Comparative Example 2 A support 5 was obtained in the same manner as in Example 1 except that the second aqueous solution of sodium silicate was not subjected to the hydrophilic treatment.

The positive lithographic printing plate obtained using the support 5 was evaluated by the evaluation method described in Example 1 for stopping stain resistance,
When the photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability were examined, the results shown in Table 1 were obtained.

Comparative Example 3 Example 1 except that the first and second hydrophilizing treatments were not performed.
In the same manner as in the above, a support 6 was obtained. The positive lithographic printing plate obtained using the support 6 was examined for stop stain property, photoreceptor residual property, erasability, fringe stain property, sludge, and printing durability by the evaluation method described in Example 1. The results shown in FIG.

Comparative Example 4 In an electrolytic surface roughening treatment, a 2.0% aqueous nitric acid solution was used at a temperature of 30 ° C. and a current density of 100 A / dm ^2.
A support 7 was obtained in the same manner as in Example 1 except that electrolysis was performed for 60 seconds with a sine wave alternating current of 0 Hz.

The positive lithographic printing plate obtained by using the support 7 was evaluated by the evaluation method described in Example 1 for stopping stain resistance,
When the photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability were examined, the results shown in Table 1 were obtained.

[0056]

[Table 1]

From the results shown in Table 1, it can be seen that all the printing plates of the present invention are excellent in stop stain property, photoreceptor residual property, erasability, fringe stain property, sludge, and printing durability.

Example 4 In the hydrophilization treatment, the substrate was immersed in a nickel oxalate aqueous solution having a concentration of 0.01 wt% and 95 ° C. for 20 seconds, and then immersed in a 0.01 wt% aqueous dextrin solution having a concentration of 80 ° C. for 30 seconds. A support 8 was obtained in the same manner as in Example 1.

The positive lithographic printing plate obtained by using the support 8 was evaluated by the evaluation method described in Example 1 for stopping stain resistance,
When the photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability were examined, the results shown in Table 2 were obtained.

Example 5 In the first hydrophilization treatment, a concentration of 0.05 wt%
Support 9 was obtained in the same manner as in Example 1 except that the substrate was immersed in an aqueous solution of ammonium acetate at 15 ° C. for 15 seconds, and then immersed in an aqueous solution of carboxymethyl cellulose at a concentration of 0.01 wt% and 80 ° C. for 15 seconds in the second hydrophilic treatment. .

The positive lithographic printing plate obtained by using the support 9 was evaluated for the stop smearing property by the evaluation method described in Example 1.
When the photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability were examined, the results shown in Table 2 were obtained.

Comparative Example 5 In the first hydrophilization treatment, the concentration was 0.05 wt% and the temperature was 95 ° C.
Was immersed in an aqueous solution of ammonium acetate for 15 seconds to obtain a support 10 in the same manner as in Example 1 except that the second hydrophilic treatment was not performed.

The positive lithographic printing plate obtained by using the support 10 was evaluated for stop stain property, photoreceptor residual property, erasability, fringe stain property, sludge, and printing durability by the evaluation method described in Example 1. However, the results shown in Table 2 were obtained.

Comparative Example 6 A support 11 was obtained in the same manner as in Example 4 except that the first hydrophilic treatment was not performed.

The positive lithographic printing plate obtained by using the support 11 was evaluated for stop stain property, photoreceptor residual property, erasability, fringe stain property, sludge, and printing durability by the evaluation method described in Example 1. However, the results shown in Table 2 were obtained.

Comparative Example 7 In the electrolytic surface roughening treatment, a 2.0% aqueous nitric acid solution was used at a temperature of 30 ° C. and a current density of 100 A / dm ^2.
A support 12 was obtained in the same manner as in Example 4, except that electrolysis was performed for 60 seconds with a sine wave alternating current of 0 Hz.

The positive lithographic printing plate obtained by using the support 12 was evaluated for stop stain property, photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability by the evaluation method described in Example 1. However, the results shown in Table 2 were obtained.

[0068]

[Table 2]

From the results shown in Table 2, it can be seen that all the printing plates of the present invention are excellent in stop stain property, photoreceptor remaining property, erasability, fringe stain property, sludge, and printing durability.

[0070]

According to the present invention, a positive photosensitive lithographic printing plate capable of obtaining a positive photosensitive lithographic printing plate which simultaneously satisfies stop stain property, photoreceptor residual property, erasability, fringe stain, sludge, and printing durability is obtained. A method for producing a printing plate support can be provided.

Claims (2)

[Claims] 1. A positive photosensitive lithographic printing plate support comprising a photosensitive layer provided on an aluminum support which has been subjected to electrolytic surface roughening treatment, anodic oxidation treatment and hydrophilic treatment in an aqueous hydrochloric acid solution in this order. In the method of producing, before or after performing the hydrophilization treatment with the carboxylate aqueous solution,
The molar ratio of ₂ / M ₂ O (M represents an alkali metal) is 3.0
-4.0, alkali metal silicate concentration 0.05-0.4.
A method for producing a support for a positive photosensitive lithographic printing plate, characterized by performing a hydrophilization treatment with an aqueous solution of an alkali metal silicate of 5 wt%. 2. A positive photosensitive lithographic printing plate support comprising a photosensitive layer provided on an aluminum support which has been subjected to electrolytic surface roughening treatment, anodic oxidation treatment, and hydrophilic treatment in an aqueous hydrochloric acid solution in this order. The method for producing a support for a positive photosensitive lithographic printing plate according to the above method, wherein the hydrophilizing treatment is performed by performing a hydrophilizing treatment with a carboxylate aqueous solution, and then performing a hydrophilizing treatment with a hydrophilic polymer aqueous solution. Method.