JPH023170B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a plate-making method using a photosensitive lithographic printing plate (hereinafter referred to as a PS plate), and in particular to a method for making a plate using a photosensitive lithographic printing plate (hereinafter referred to as a PS plate). This invention relates to an improvement in a plate-making method in which a burning process is performed after image exposure and development.

[Prior art]

U.S. Patent No. 4063507, U.S. Patent No. 4191570, U.S. Patent No.
No. 4294910, No. 4355096, British Patent No. 1555233
No. 1,575,200 discloses that in a plate making method in which a PS plate is subjected to image exposure and development and then subjected to a burning process, sodium dodecylphenoxybenzenedisulfonate, alkyl Aromatic sulfonates such as sodium naphthalene sulfonate, methylene bis(sodium naphthalene sulfonate), sodium salt of sulfonated alkyl diphenyl oxide, sodium dodecylbenzene sulfonate;
Inorganic acid salts such as lithium nitrate, sodium nitrate, sodium borate, ammonium borate, sodium sulfate, and sodium phosphate; Carboxy-containing amines or salts thereof such as sodium ethylenediaminetetraacetate and hydroxyalkylethylenediaminetriacetic acid; gum arabic, cellulose ether, etc. By treating with an aqueous solution of a water-soluble polymeric substance (hereinafter referred to as an aqueous pre-burning treatment liquid), a lithographic printing plate without stains in non-image areas can be obtained without surface preparation after burning treatment. is disclosed.

However, even with lithographic printing plates obtained by such plate-making methods, stains are often observed in non-image areas, and they are often treated with a plate cleaner or fluorocarbons after the burning process. The drawback was that it had to be treated with a surface preparation solution containing chemicals. In particular, this tendency occurs when printing is started after being left for a long time after the burning process (hereinafter referred to as plate placement), or when the desensitization process (so-called gumming) that is usually performed after the burning process is incomplete. This was noticeable in the cases where the degreasing was carried out with a desensitized gum having a weak desensitizing power.

[Purpose of the invention]

Accordingly, it is an object of the present invention to provide an improved plate-making method that includes a burning process. More specifically, it is an object of the present invention to provide a plate-making method capable of producing a lithographic printing plate without stains in non-image areas without treating with a plate cleaner or surface-leveling liquid after burning treatment.

Another object of the present invention is to provide a plate-making method capable of obtaining a lithographic printing plate that does not cause stains in non-image areas even if printing is started after plate placement after burning treatment.

[Structure of the invention]

As a result of extensive research, the present inventors have found that by using an aqueous burning pretreatment liquid containing at least one compound selected from the group consisting of phytic acid, hexametaphosphoric acid, and their salts,
It has been found that the above objectives are achieved.

The phytates include sodium salts, potassium salts, ammonium salts, and mixed salts thereof, and the hexametaphosphates include sodium salts, potassium salts, and the like. Among these phytic acid, hexametaphosphoric acid and their salts,
Particularly preferred compounds are sodium hexametaphosphate and potassium hexametaphosphate.

Phytic acid, hexametaphosphoric acid, or their salts can be used alone or in combination of two or more compounds, and their concentrations in aqueous solutions (i.e., aqueous burning pretreatment liquids) are effective over a wide range; from about 0.1 wt.% to saturation concentration, more preferably from 0.1 to 15 wt.%, most preferably from 0.5 to 10
It is contained within a range of % by weight.

The burning pretreatment liquid used in the present invention includes:
It is preferable to contain the components of a conventionally known aqueous pre-burning treatment liquid, which can suppress stains on the non-image areas of the lithographic printing plate that are likely to occur during the burning process, and also prevent high-temperature treatment after the burning process.・Even if the plate is placed in a humid environment, no stains will occur in the non-image area during printing.

Such components include anionic surfactants, nonionic surfactants, amphoteric surfactants, other organic acids and their salts, inorganic salts, water-soluble polymer substances, and the like. Among these, anionic surfactants are preferred because they are most effective in suppressing stains in non-image areas.

Examples of anionic surfactants include dodecylbenzene sulfonate, alkylnaphthalene sulfonate, alkylnaphthalene disulfonate, alkyl diphenyl ether sulfonate, alkyl diphenyl ether disulfonate, methylene bis(naphthalene sulfonate), and naphthalene. Anionic surfactants with aromatic sulfonic acid groups such as formalin condensates of sulfonates, dialkyl sulfosuccinate ester salts, α-olefin sulfonates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates , alkyl phosphate ester salts, etc. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, aliphatic monoglyceride, and sorbitan fatty acid ester. Examples of amphoteric surfactants include alkylcarboxybetaine, alkylaminocarboxylic acid, alkylimidazoline, and other natural surfactants such as saponin.

In addition, other organic acids and their salts include malic acid, naphthalene sulfonic acid, sulfosalicylic acid, alkyl sulfonic acid, isethionic acid, hydroxyalkyl sulfonic acid, citric acid, gluconic acid, succinic acid, tartaric acid, oxalic acid, acetic acid, and these. Includes sodium, potassium, lithium, and ammonium salts.

Inorganic salts include sodium salts, potassium salts, lithium salts, ammonium salts, etc. of phosphoric acid, acetic acid, nitric acid, sulfuric acid, boric acid, and the like.

Furthermore, water-soluble polymeric substances include gum arabic, dextrin, polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, polymethacrylic acid, and the like.

Among the above compounds, preferred are compounds having a sulfonic acid group, especially aromatic sulfonic acids and salts thereof, and malic acid and salts thereof.

The above-mentioned compounds can be contained alone or in combination in the water burning pretreatment liquid, and the concentration varies depending on the compound used, but is about 0.05 to 25% by weight. , particularly preferably in the range of 1 to 20% by weight.

The aqueous burning pretreatment liquid used in the present invention can further contain an inorganic acid or alkali. Preferred acids include phosphoric acid, nitric acid, boric acid, sulfuric acid, etc., and preferred alkalis include sodium hydroxide, potassium hydroxide, etc.

By containing these acids and alkalis, it is possible not only to further suppress the occurrence of stains in non-image areas after the burning process, but also to control the pH of the aqueous burning pretreatment liquid preferably within the range of 3 to 10. This can prevent the hydrophilic surface of the aluminum support from being etched.

In addition, the aqueous burning pretreatment liquid used in the present invention includes pigments (for example, water-soluble dyes such as crystal violet, methylene blue, tartrazine, orange, and congo red), antifoaming agents,
Preservatives and the like can be added.

The aqueous burning pre-treatment liquid used in the present invention is used to image-expose the PS plate, develop it, and wash it with water if necessary, and then removes unnecessary parts for printing with a correction agent, leaving the printing plate with no room for further correction. Once created, it can be dried if necessary and applied before the burning process. The method is to apply the pretreatment agent onto the planographic printing plate using a sponge or absorbent cotton impregnated with the pretreatment agent, or to immerse the printing plate in a vat filled with an aqueous burning pretreatment liquid. The coating can be carried out by various methods such as coating with an automatic coater. Further, after coating, using a squeegee or a squeegee roller to make the coating amount uniform gives more favorable results.

The lithographic printing plate treated in this manner is dried if necessary, and then heated to a high temperature with a burning processor (for example, Burning Processor 1300 sold by Fuji Photo Film Co., Ltd.). The heating temperature and time in this case are preferably in the range of 180 to 300°C for 7 to 20 minutes, although it depends on the type of component forming the image.

The burn-treated lithographic printing plate can be subjected to conventional treatments such as washing with water and gumming, if necessary.

Although the plate making method according to the present invention can be applied to various PS plates, it is particularly suitable for PS plates having an aluminum plate as a support. A preferred such PS version is, for example, British Patent No. 1350521
British patent No. A photosensitive layer made of a mixture of a diazo resin and a polymer having hydroxyethyl methacrylate units or hydroxyethyl acrylate units as main repeating units as described in the specifications of No. 1460978 and No. 1505739 is placed on an aluminum plate. A negative-tone PS plate such as the one prepared above, and a photosensitive layer made of a mixture of an o-quinone diazide photosensitive material and a novolac type phenol resin as described in JP-A-50-125806 were provided on an aluminum plate. Includes positive PS version. Furthermore, a PS plate in which a photosensitive layer of a photocrosslinkable photopolymer is provided on an aluminum plate as specifically shown in U.S. Pat. No. 3,860,426, and U.S. Pat.
PS plate in which a photosensitive layer of a photopolymer composition as described in the specifications of British Patent No. 4072528 and British Patent No. 4072527 is provided on an aluminum plate, and the specifications of British Patent No. 1235281 and British Patent No. 1495861. A PS plate in which a photosensitive layer consisting of a mixture of azide and a water-soluble polymer is provided on an aluminum plate as described in the book is also preferred. Among these PS plates, a particularly preferred PS plate to be used in the plate making method of the present invention is a positive PS plate having a photosensitive layer consisting of an o-naphthoquinone diazide compound and a novolac resin, and is disclosed in US Pat. No. 4,259,434. 2 from the bottom of the 3rd column
It is explained in detail in line 6 to column 6, line 14.

〔Effect of the invention〕

According to the plate making method of the present invention, there is no need to perform a surface smoothing treatment after the burning treatment. Despite this, a lithographic printing plate with excellent printing durability and high oil sensitivity in the image area without staining in the non-image area can be obtained. Moreover, according to the plate making method of the present invention, there is an excellent effect that the non-image area will not be stained during printing even if the plate is placed under high temperature and high humidity for a long time after the burning process. Furthermore, it has been found that according to the plate making method of the present invention, even if the desensitizing process after the burning process is omitted, there is an unexpected effect that stains do not occur in non-image areas.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 2 parts by weight of naphthoquinone-(1,2)-diazide(2)-5-sulfonic acid ester of 1,5 dihydroxynaphthalene and 4 parts by weight of novolak type cresol-formaldehyde resin were mixed with 100 parts by weight of ethylene glycol monomethyl ether. dissolved in Next, this solution was applied onto a grained aluminum plate having a thickness of 0.24 mm so that the weight after drying was 2.5 g/m ² . Positive mold made in this way
From a distance of 1m with the PS version in close contact with the transparency
After exposure for 30 seconds using a 3KW metal halide lamp, the film was developed by immersing it in a 5% by weight aqueous solution of sodium silicate for about 1 minute. Next, after washing with water, an aqueous burning pretreatment liquid having the following composition was applied and dried.

Sodium isopropylnaphthalene sulfonate
100 g Sodium hexametaphosphate 15 g Pure water 1 The printing plate thus treated was heated in a commercially available burning processor at a temperature of 260° C. for 6 minutes. After leaving the obtained plates indoors for three days, they attached them to an offset printing machine and printed on them. After printing, a few sheets of beautiful prints were obtained. When they continued printing, they obtained 150,000 beautiful prints. It was done.

Comparative Example 1 A lithographic printing plate made under exactly the same conditions as in Example 1 up to development was treated with an aqueous burning pretreatment liquid having the same composition as that used in Example 1, except that it did not contain sodium hexametaphosphate. The sample was then subjected to the same burning process and left as it was indoors for three days.

When this lithographic printing plate was used for printing, scumming occurred in the non-image area from the beginning of printing.

Example 2 A plate obtained in the same manner as in Example 1 up to the development and water washing steps was treated with an aqueous burning pretreatment liquid having the following composition.

d,l-Sodium malate 100g Sodium phytate 7g Sodium hexametaphosphate 10g Pure water 1 The printing plate obtained by the above treatment was treated in a burning processor in the same manner as in Example 1. After gumming the resulting plate, 35
It was left overnight at 85% RH. After that, when I attached it to an offset printing machine and started printing, I was able to get beautiful prints after just a few pages, and when I continued printing, I got 150,000 beautiful prints.

Comparative Example 2 Instead of the aqueous burning pretreatment liquid used in Example 2, treatment was performed with an aqueous burning pretreatment liquid having the following composition.

d,-Malic acid 100g Pure water 1 Other than that, plate making and printing were carried out in the same manner as in Example 2, but minute dot-like stains were formed over the entire surface from the start of printing to the non-image area. However, I was unable to obtain a satisfactory print.

Example 3 After electrolytic graining with a mixture of dilute nitric acid and dilute hydrochloric acid,
A photosensitive solution similar to that in Example 1 was applied onto a 0.3 mm thick aluminum plate that had been anodized in 15% by weight sulfuric acid at a current density of 1.6 amperes/dm ² for 2 minutes. A positive PS version was created.

Closely attach a transparency to this from a distance of 1 meter.
After exposure for 40 seconds using a 3KW metal halide lamp, the film was developed by immersing it in a 7% by weight aqueous sodium silicate solution for about 1 minute.

After washing with water, it was treated with an aqueous burning pretreatment liquid having the composition shown below, and treated in the same manner as in Example 1 at 240° C. for 4 minutes in a burning processor.

Dodecylphenoxybenzenedisulfonic acid 80g Phosphoric acid (85%) 3g Sodium hexametaphosphate 15g Pure water 1 The obtained plate was printed on an offset printing machine without gumming.

From the beginning of printing, beautiful prints were obtained in just a few sheets, and by continuing the process, we were able to obtain approximately 300,000 prints.

Comparative Example 3 A plate was made and printed in the same manner as in Example 3, except that a liquid with the following composition was used instead of the aqueous burning pretreatment liquid used in Example 3. This resulted in staining, and the halftone dot images in the shadow areas tended to smudge, making it impossible to obtain satisfactory printed matter.

Sodium dodecylphenoxybenzenedisulfonate 80g Phosphoric acid (85%) 3g Pure water 1 Example 4 Polyhydroxyphenyl fluoride obtained by condensation polymerization of acetone and pyrogallol as described in Example 1 of U.S. Pat. No. 3,635,709 The sand shown in Example 3 was prepared by dissolving 4 parts by weight of ester of enyl and naphthoquinone-1,2-diazide(2)-5-sulfonic acid and 4 parts by weight of novolac type cresol formaldehyde resin in 100 parts by weight of ethylene glycol monomethyl ether. A positive PS plate was prepared by coating a polished and anodized aluminum plate with a dry weight of 2.5 g/m ² .

This PS plate was exposed under the same conditions as in Example 1.
After development and washing with water, an aqueous pre-burning treatment solution having the following composition was applied, followed by burning treatment at 260°C for 5 minutes.

d, -Sodium malate 200g Sodium phytate 20g Citric acid 10g Pure water 1 When the obtained lithographic printing plate was printed on an offset printing machine without gumming, beautiful prints were obtained in just a few sheets from the start of printing, and Subsequently, we were able to obtain 200,000 prints.

Example 5 A solution was prepared by dissolving 20 parts by weight of Cierasac and 3 parts by weight of a diazo resin obtained by condensing p-toluenesulfonate of p-diazodiphenylamine with formaldehyde in 80 parts by weight of dimethylformamide.
On the other hand, a grained aluminum plate was immersed in a 0.2% aqueous solution of potassium zircon fluoride at 80°C for 3 minutes to make it hydrophilic, then washed with water and dried. It was coated to give a coating weight of g/m ² .

The negative PS plate obtained in this way was passed through a transparent negative for 1 m using a 3KW metal halide lamp.
After exposure for 30 seconds from a distance of 30 seconds, and immersing it in an aqueous solution of 20% by weight of isopropyl alcohol for about 1 minute, the surface was lightly rubbed with absorbent cotton, and only the unexposed areas were peeled off and the surface of the support was exposed.

After washing with water, the aqueous pre-burning treatment liquid used in Example 1 was applied and dried, and after performing the burning treatment under the same conditions as in Example 1, it was attached to an offset printing machine and printed. I was able to obtain beautiful prints with just one sheet, and when I continued printing, I was able to obtain 150,000 prints with almost the same tone as the first print.

Example 6 After graining with pumice/water slurry and a nylon brush, anodizing treatment (2A/d in 20% sulfuric acid)
m ² Anodized for 2 minutes. ) and then treated with a 2.5% by weight aqueous solution of sodium silicate at 70°C for 1 minute.
A 0.3mm aluminum plate was made.

A photosensitive liquid having the following composition was applied to this aluminum plate so that the weight after drying was 2.0 g/m ² .

Copolymer of 2-hydroxyethyl methacrylate/acrylonitrile/ethyl methacrylate/methacrylic acid = 37/34/22/7 (mol%)
5.0g Hexafluorophosphate of p-diazodiphenylamine formaldehyde condensate 0.5g Victoria Pure Blue-BOH (Hodogaya Chemical Co., Ltd.
Co., Ltd.) 0.1 g Polyphosphoric acid 0.05 g 2-methoxyethanol 95 ml Water 5 ml The thus obtained negative PS plate was passed through a transparent negative using a 3 KW metal halide lamp for 1 m.
It was exposed to light for 30 seconds from a distance of , and developed using the following developer.

Benzyl alcohol 30ml Diethanolamine 10g Sodium sulfite 5g Sodium isopropylnaphthalene sulfonate 10g Water 1 After washing with water, apply the aqueous burning pretreatment liquid used in Example 2 and dry it, and then perform the burning treatment under the same conditions as Example 2. When I attached it to an offset printing machine and printed it, I was able to get beautiful prints in just a few pages from the start, and when I continued printing, I was able to get 200,000 prints that were almost the same as the prints.

Example 6 After degreasing (immersion in 10% tribasic sodium phosphate aqueous solution for 1 minute), graining was performed using pumice/water slurry and a nylon brush, and anodizing treatment (2A/dm ² 4 in 20% sulfuric acid) anodized)
A 0.3 mm aluminum plate was prepared.

Apply the following solution to this plate and heat it to 200°C.
Dry for a minute.

Polyvinyl alcohol 0.1g methanol 50ml 50ml water Subsequently, the next solution was applied and dried.

(Polyvinyl cinnamate (Eastman Kodak)
20 g 2-methoxyethanol 10 g 2-methoxyethyl acetate 10 g 2-methoxyethyl acetate The plate thus obtained was exposed to light through a transparent negative and developed with a developer having the following composition.

(2-methoxyethyl acetate 890g glycerin 40g water 20g acetic acid 50g) After washing with water, it was treated with the aqueous burning pretreatment liquid used in Example 4, and burned at 200°C for 5 minutes. After desensitizing the obtained plate with a dextrin solution, it was mounted on an offset printing machine and printed, and beautiful printed matter could be obtained in just a few sheets after printing.

Claims (1)

[Claims] 1. In a plate-making method in which a photosensitive lithographic printing plate is exposed and developed, an aqueous pre-burning treatment liquid is applied, and then a lithographic printing plate is prepared by burning treatment, the pre-burning treatment liquid contains phytic acid, hexametaphosphoric acid and A plate-making method characterized by containing at least one compound selected from the group consisting of salts thereof.