JPS62242945A - Photomechanical process - Google Patents

Abstract

PURPOSE:To prevent the ground stain of a lithographic printing plate and to improve the sensitivity of the image part by applying an aqueous soln. contg. a specified condensed resin to the printing plate after development and by burning the printing plate. CONSTITUTION:A photosensitive lithographic printing plate is imagewise exposed and developed. An aqueous soln. contg. a condensed resin is then applied to the printing plate. After the soln. is dried, the printing plate is burned. The condensed resin is prepd. by condensing aromatic sulfonic acid or a salt thereof such as sodium benzenesulfonate with aldehyde such as formaldehyde. By this method, desensitization after burning can be eliminated and a lithographic printing plate having superior printing resistance is obtd. The non-image part of the printing plate is not stained and the image part has high sensitivity.

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, and in particular, after imagewise exposure and development of a photosensitive lithographic printing plate using a metal as a support, burning is performed. This relates to a plate-making method when used as a plate.

[Prior art]

Lithographic printing is a printing method that skillfully takes advantage of the property that water and oil essentially do not mix.The printing plate surface has two areas: one area that accepts water and repels oil-based ink, and the other area that repels water and accepts oil-based ink. The former is a non-image area and the latter is an image area. Therefore, the photosensitive composition used for preparing a lithographic printing plate is required to have the property of repelling water and accepting oil-based ink after image formation.

There are two types of photosensitive compositions used to create lithographic printing plates: positive type and negative type.
Those made of quinonediazide compounds are widely used.

A positive-working photosensitive lithographic printing plate is one in which an O-quinonediazide compound alone or mixed with an alkali-soluble resin such as a novolac type phenol resin or a cresol resin is coated on a suitable support such as metal or plastic.
When exposed to actinic light through a transparency, the 0-quinonediazide compound in the exposed areas decomposes and becomes alkali-soluble, so it is easily removed by an aqueous alkaline solution to give a positive image. Therefore, when a support having a hydrophilic surface is used, the portion removed with the alkaline aqueous solution exposes the hydrophilic surface of the support, and this portion receives water and repels ink. On the other hand, the portion that remains as an image is lipophilic and will absorb ink.

On the other hand, many negative photosensitive compositions use diazonium salts, azide compounds, or photopolymerizable compounds, and these photosensitive compositions are used alone or mixed with additives such as suitable resins, Painted on top. When a support with a hydrophilic surface is used, the unexposed areas are removed by a developer,
The hydrophilic surface of the support is exposed and this area receives water and repels ink. On the other hand, the portion that is cured by exposure and remains as an image upon development is lipophilic and accepts ink.

When the lithographic printing plate created in this way is printed on an offset printing machine, beautiful printed matter can be obtained. Planographic printing plates made from such photosensitive planographic printing plates can produce tens of thousands of beautiful prints by appropriately selecting the composition of the support and the photosensitive layer coated thereon.
In particular, by using a textured and anodized aluminum plate as a support, it is possible to obtain up to 100,000 beautiful prints.

However, there is also a desire to obtain many more printed sheets from a single printing plate. In such cases, a method is to strengthen the image area by exposing and developing a photosensitive lithographic printing plate using a metal plate such as aluminum or zinc as a support in the usual way, and then heating it at a high temperature (so-called burning treatment). is valid.

That is, by performing the burning process, the number of printed matter obtained from one lithographic printing plate can be increased several times compared to the case where the burning process is not performed.

Furthermore, when printing with special printing inks such as ultraviolet curing inks or low-temperature drying inks that contain a large amount of components that dissolve images on printing plates, printing plates made using normal methods that do not undergo burning treatment may cause the image areas to dissolve. However, when the burning process is applied, the solvent resistance of the image area is greatly improved, so even with the special printing inks mentioned above, A sufficient number of printed materials can be obtained.

However, the non-image area of the printing plate (i.e., the area where the hydrophilic support surface is exposed by development), which was hydrophilic before the treatment, loses its hydrophilicity and becomes receptive to printing ink due to the burning treatment. As a result, stains (so-called background stains) occur on the background and background of printed matter. Heating to an extent that does not cause such background smearing does not produce a burning effect, and image reinforcement is not achieved. Therefore,
In order to prevent staining of the non-image area caused by the burning process, a surface smoothing process must be performed. Various proposals have been made in the past as a surface smoothing treatment used before and/or after this burning treatment step.

For example, after the burning process, a fluoride aqueous solution such as hydrofluoric acid, borohydrofluoric acid, silicohydrofluoric acid, etc. However, these fluorides are classified as poisonous and deleterious substances and pose many problems in terms of pollution control.

Furthermore, when this surface smoothing treatment is applied, the metal surface of the support corrodes, making the surface more susceptible to scratches and becoming more susceptible to abrasion. ) is lost, background smearing occurs, and further printing is no longer possible.

In addition, as a processing method to prevent the hydrophilicity of the non-image area from decreasing before the burning process, Japanese Patent Laid-Open No. 51
Publication No. 34001 discloses treatment with an aqueous solution of an organic sulfonic acid salt such as alkylnaphthalene sulfonic acid sorter, alkyldiphenyl ether sodium sulfonate, and lithium nitrate before burning. Among these, aqueous solutions of salts of organic sulfonic acids such as sodium alkylnaphthalene sulfonate and sodium alkyl diphenyl ether sulfonate have extremely high foaming properties.
It is unsuitable for use in the spray circulation type processors that are currently widely used, and has the drawback that it cannot automate the plate-making process. Furthermore, when treated with a solution containing lithium nitrate and burned, the prevention of scumming was not sufficient. Furthermore, Japanese Patent Publication No. 55-28062 discloses a method of treating with an aqueous solution containing sublimable boric acid and its salts before burning, and then performing burning in the presence of the compound. Prevention of scumming was not sufficient. In particular, depending on the conditions such as water washing and gumming performed after the burning process, in other words, water washing may be insufficient, or dextrin (dextrin), which has a weak hydrophilic ability as a desensitized gum liquid, may be affected.
When IJ-type gum liquid is used, there is a drawback that scumming tends to occur. Furthermore, JP-A No. 52-6205 discloses that water-soluble organic substances such as gum arabic, cellulose ether, and polyacrylic acid, and/or borates, phosphates, sulfates, alkali metals, and alkaline earth metals are added before the burning process. It has been shown that treatment with an aqueous solution of water-soluble inorganic salts such as halides such as When an aqueous solution of a water-soluble polymer is used, there is a drawback that it becomes difficult for the image area to receive ink during printing, resulting in so-called inking failure. Furthermore, JP-A-57-52057 discloses that ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid,
A method of treatment with an aqueous solution containing a carboxyl group-containing amine or a salt thereof such as hydroxyalkylethylenediaminetriacetic acid is disclosed. However, this method could not be said to be sufficiently effective in preventing background stains.

[Purpose of the invention]

An object of the present invention is 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 including a burning process, which can produce a lithographic printing plate that is free from scumming and has excellent oil sensitivity in image areas.

Another object of the present invention is to provide a plate-making method including a burning process that can be automated by using a spray circulation type processing machine or the like.

A further object of the present invention is to provide a plate-making method that can obtain a lithographic printing plate that does not cause background stains in non-image areas even if printing is started after printing without desensitizing treatment after burning treatment. It is to provide.

[Structure of the invention]

The present inventor proposed that a processing liquid (hereinafter referred to as a burning pre-treatment liquid) applied to a lithographic printing plate before burning treatment is a condensation resin of an aromatic compound and an aldehyde, which contains aromatic compounds in the molecule. It has been found that the above objects can be achieved by using an aqueous solution containing a condensation resin containing a sulfonic acid group or a salt thereof.

The above-mentioned condensation resin used in the present invention is a product obtained by condensing aromatic sulfonic acid or its salt with aldehyde such as formaldehyde, paraformaldehyde, acetaldehyde, or furfural. can be mentioned.

Aromatic sulfonic acids used in condensation include benzenesulfonic acid, dodecylbenzenesulfonic acid, alkylbenzenesulfonic acids, sulfanilic acid, sulfobenzoic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, phenolsulfonic acid, methoxyphenolsulfonic acid, and naphthalenesulfonic acid. , diphenyl ether sulfonic acid,
Dodecyl diphenyl ether sulfonic acid, dodecyl diphenyl ether sulfonic acid, di-1-naphthyl ether sulfonic acid, diphenyl sulfide disulfonic acid, diphenyl sulfide sulfonic acid, dodecyl diphenyl sulfide sulfonic acid, methoxydiphenyl sulfide sulfonic acid, n-butyldinaphthylsulfide sulfonic acid ,
Benzophenone sulfonic acid, benzophenone disulfonic acid, dodecylbenzophenone disulfonic acid, diphenylamine sulfonic acid, diphenylamine disulfonic acid, dinaphthylamine sulfonic acid, dinaphthylamine disulfonic acid, dodecyl diphenylamine disulfonic acid, diphenyl sulfoxide sulfonic acid, diphenyl sulfone sulfonic acid, diphenylmethane sulfonic acid, Examples include dodecyl diphenylmethane disulfonic acid and bisphenol A-disulfonic acid.

These condensates contain an excess of aromatic sulfonic acid to aldehyde, for example, 1 to 1.5 mol, preferably 1.1 to 1.5 mol, of aromatic sulfonic acid to 1 mol of aldehyde.
It can be easily obtained by adding 1.3 mol and condensing under acidic conditions. In this case, in the present invention, it is preferable to use formaldehyde or paraformaldehyde as the aldehyde, and it is preferable to use alkylbenzenesulfonic acid or dodecyl diphenyl ether disulfonic acid as the aromatic sulfonic acid.

The condensate used in the present invention may be produced by the method described above, or may be produced by condensing an aromatic compound having no sulfonic acid group with an aldehyde and then sulfonating the condensate by a known method. Although various molecular weights can be used in the present invention, those with a molecular weight of 300 to 30,000, preferably 500 to 10,000 are preferably used.

Examples of the salt include compounds such as IJium salt, potassium salt, lithium salt, ammonium salt, and amine salt.

The above compounds can be used alone or in combination of two or more, and are 0.1 to 30% by weight, more preferably 0.1 to 30% by weight, based on the total weight of the burning pretreatment liquid according to the present invention.
．． It is contained in a range of 5 to 20% by weight.

The burning pretreatment liquid used in the present invention may further contain various additives.

Examples of such additives include surfactants, various salts, acids, alkalis, and the like.

The surfactant helps the burning pretreatment liquid used in the present invention to be uniformly applied to the surface of the lithographic printing plate, and also partially suppresses the occurrence of stains in non-image areas due to the burning process. There is. Preferred surfactants are anionic surfactants, especially those containing a sulfonic acid group such as alkylbenzene sulfonates, alkyldiphenyl ether disulfonates, alkylnaphthalene sulfonates, aldehyde condensates of alkylnaphthalene sulfonates, and α-olefin sulfonates. Particularly preferred are surfactants and sulfate-based surfactants such as lauryl sulfate, polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkyl phenyl ether sulfate. The surfactant is suitably included in the burning pretreatment liquid in an amount of about 0.05% to about 10% by weight, preferably in a range of 0.1 to 5% by weight.

Furthermore, an acid, alkali or salt can be used for pH adjustment in the burning pretreatment liquid used in the present invention, if necessary. As acids it is possible to use mineral acids and organic acids. Mineral acids such as nitric acid, sulfuric acid, phosphoric acid, organic acids such as citric acid, conolic acid, oxalic acid, tartaric acid, acetic acid, malic acid, potassium salts, lithium salts, sodium salts or ammonium salts of these acids, Alternatively, alkali metal hydroxides, carbonates, hydrogen carbonates, etc. may be mentioned.

These acids, salts, and alkalis adjust the pH of the burning pretreatment liquid used in the present invention from 2 to 10, preferably from 3 to 8.
It can be contained in an amount within the range of.

Furthermore, the burning pretreatment liquid used in the present invention contains gum arabic, dextrin, carboxymethyl cellulose, water-soluble polymer substances such as polyacrylic acid, polymethacrylic acid, and salts thereof (such as sodium salts), and pigments. , antifoaming agents, preservatives, etc. may also be added.

In the present invention, the burning pretreatment liquid is used to image-expose a photosensitive lithographic printing plate, develop it, wash it with water if necessary, and then remove unnecessary portions for printing with a correction agent. After it is created, it is dried if necessary and applied before the burning process. Methods for this include coating the planographic printing plate with a sponge or absorbent cotton impregnated with the pretreatment liquid, immersing the printing plate in a vat filled with the treatment liquid, and applying the coating automatically. Application with a coater etc. is applied. Also, after applying, use a squeegee or
To make the amount of application uniform with a squeegee roller,
Gives more favorable results.

The lithographic printing plate coated with the burning pretreatment liquid is dried if necessary, and then heated to a high temperature using a burning processor (for example, Burning Processor 1300 sold by Fuji Photo Film). The heating temperature and time in this case are preferably in the range of 180 to 300° C. for 1 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. It is possible to omit so-called desensitization treatment such as.

The plate making method according to the present invention can be applied to various photosensitive planographic printing plates, but in particular, photosensitive planographic printing plates (printing plates to which photosensitization has been imparted in advance) using an aluminum plate as a support, PS
called a version. ) can be suitably used. Such P
A preferred S version is, for example, British Patent No. 1.350.
521, a photosensitive layer made of a mixture of a diazo resin (salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and shellac is provided on an aluminum plate, British Patent No. 1 .460.9
No. 78 and No. 1.505.739, the photosensitive layer is made of a mixture of a diazo resin and a polymer containing hydroxyethyl methacrylate units or hydroxyethyl acrylate units as main repeating units. A negative 28 plate, such as one provided on an aluminum plate, and a photosensitive layer consisting of a mixture of an 0-quinonediazide photosensitive material and a novolac type phenolic resin, as described in JP-A-50-125.806, are used. Includes 28 positive plates mounted on aluminum plates. Further, 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 photopolymerizable photopolymer composition as described in Patent Nos. 72.528 and 4.072.527 is provided on an aluminum plate, British Patent No. 1.235 .281 and 1.495.86
Also preferred is a PS plate in which a photosensitive layer made of a mixture of azide and a water-soluble polymer is provided on an aluminum plate as described in each specification of No. 1. Among these PS plates, a particularly preferable PS plate to be subjected to the plate making method of the present invention is a 0-
It is a positive type 28 plate having a photosensitive layer made of a naphthoquinone diazide compound and a novolak resin, and is published in US Pat. No. 4.
This is explained in detail in the specification of No. 259.434, column 3, line 2 from the bottom 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, since the burning pretreatment liquid used in the present invention has a low foaming property, it can be applied to planographic printing plates using a spray circulation type processing machine, which has great advantages such as automation of plate making work.

Moreover, according to the plate making method of the present invention, desensitization treatment after burning can be omitted. After the burning process, it not only has the excellent effect of not causing background smudges even after being placed on the plate for a long time, but also has the effect of preventing scratches from forming on the plate surface, thus making it difficult for scratches and stains to occur. .

〔Example〕

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

Example 1 Naphthoquinone of 1.5-dihydroxynaphthalene (1
, 2)-Diazide (2)-5-sulfonic acid ester (2 parts by weight) and novolac type cresol-formaldehyde resin (4 parts by weight) were dissolved in 100 parts by weight of ethylene glycol monomethyl ether. 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/m5. The positive-working photosensitive lithographic printing plate thus prepared was brought into close contact with the transparency and exposed for 30 seconds from a distance of 1 meter using a 3KW metal halide lamp, and then exposed to a 5% by weight aqueous solution of IJium silicate for about 1 minute. It was immersed and developed. Next, after washing with water, a burning pretreatment liquid having the following composition was applied and dried.

Pure water □ 900
g The printing plate thus treated was heated in a commercially available burning processor at a temperature of 260° C. for 6 minutes.

After cooling, it was gummed, and when this printing plate was attached to an offset printing machine and printed, beautiful prints were obtained after just a few sheets, and when printing was continued, 150,000 beautiful prints were obtained.

Comparative Example 1 A lithographic printing plate treated under exactly the same conditions as in Example 1 up to development was treated with a 4% by weight ammonium borate aqueous solution instead of the burning pretreatment liquid used in Example 1, and subjected to the same burning treatment. and pulled gum. When this lithographic printing plate was used for printing, smearing occurred in the halftone dot image in a portion of the shadow from the beginning of printing, and it was necessary to remove the dirt from the smeared area with a plate cleaner.

Example 2 Examples 1 and 2 were deposited on a 0.3 mm thick aluminum plate that had been grained and anodized (anodized in 15 wt% sulfuric acid at a current density of 1.6 amperes/dm' for 2 minutes). A positive photosensitive lithographic printing plate was prepared by applying the same photosensitive solution.

A transparency was brought into close contact with this and exposed for 40 seconds using a metal halide lamp at a distance of 1 m, and then developed by immersing it in a 7% by weight aqueous solution of sodium silicate for about 1 minute.

This lithographic printing plate is processed using an automatic through-type burning processor [
Made of process materials ■, applying pre-burning treatment liquid, burning, and gumming are performed continuously. ] to form a continuous ring. Here, the burning temperature was preheated at 150°C, postheated at 240°C, and the time required for passage through the filtration was about 3 minutes, and the burner pretreatment liquid used had the following composition.

Sodium isopropylnaphthalene sulfonate □ 3g Sodium hexametaphosphate □ 5g Pure water
□ When the lithographic printing plate obtained by the 900g burning process was directly attached to an offset printing machine and printed, beautiful prints were obtained in just a few prints, and 300,000 prints were obtained by continuing the printing process.

Comparative Example 2 The development process was carried out in the same manner as in Example 2, and the processing liquid in the burning processor was treated with an 8% by weight aqueous solution of sodium alkyl diphenyl ether sulfonate, and the other conditions were the same as in Example 2. Significant foaming occurred from the spray pipe and its tank at the area where the treatment liquid was applied, and the liquid overflowed from the tank, necessitating the operation of the automatic treatment machine to be stopped.

Example 3 In the same manner as in Example 1, however, an aqueous solution having the following composition was used as the burning pretreatment liquid, and the same results as in Example 1 were obtained.

Hydroxylation power, Lium - 2g Pure water □ 895g
Example 4 Polyhydroxyphenyl and naphthoquinone-1,2 obtained by polycondensation of acetone and pyrogallol as described in Example 1 of U.S. Pat. No. 3,365,709
- 4 parts by weight of diazide (2)-5-sulfonic acid ester and 4 parts by weight of Novolabuku-type talesol-formaldehyde resin were dissolved in 100 parts by weight of ethylene glycol monomethyl ether, and subjected to the graining and anodizing treatment used in Example 2. The dry weight of the aluminum plate is 15g/rn'
A positive photosensitive lithographic printing plate was prepared.

After this positive photosensitive lithographic printing plate was exposed to light, developed and washed with water under the same conditions as in Example 1, a burning pretreatment liquid having the following composition was applied, and then a burning treatment was performed at 260° C. for 5 minutes.

Sodium malate □ 15g pure water
□ When the lithographic printing plate obtained weighing 885 g was installed in an offset printing machine without gumming and printed, beautiful prints were obtained in just a few prints, and 200,000 prints were obtained by continuing the process. was completed.

Example 5 A solution was prepared by dissolving 20 parts by weight of shellac and 3 parts by weight of a diazo resin obtained by condensing p-)luenesulfonate of p-diazodiphenylamine with formaldehyde in 80 parts by weight of dimethylformamide. On the other hand, a grained aluminum plate was heated to 80°C with 0.2% potassium zirconium fluoride.
After being immersed in an aqueous solution for 3 minutes to make it hydrophilic,
Wash with water, dry, and add the above prepared solution to a weight of 2.0g after drying.
/m''.

The negative photosensitive planographic printing plate thus obtained was exposed through a transparent negative for 30 seconds with a 3K11 metal halide lamp from a distance of 1 m, and
After being immersed in an aqueous solution of % by weight for about 1 minute, the surface was lightly rubbed with absorbent cotton, and only the unexposed areas were peeled off cleanly, exposing the surface of the support.

After washing with water, apply the burning pretreatment liquid used in Example 1,
After drying and performing a burning process under the same conditions as in Example 1, it was installed on an offset printing machine and printed. Beautiful prints were obtained in about 10 sheets from the beginning of printing, and when printing continued as it was, the results were as follows. We were able to obtain 150,000 pieces of printed matter with almost no change in condition.

Example 6 Graining with pumice/water slurry and a nylon brush, anodizing treatment (anodizing at 2A/d'' for 2 minutes in 20% sulfuric acid), followed by a 2.5% by weight aqueous solution of sodium silicate at 70°C. An aluminum plate with a thickness of 0.3 mm was prepared by treating it for 1 minute.

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

Copolymer of Rayi/Tsukukuriru Uchimi, 3//64/22/7 (weight ratio) 5.0g Methyl cellosolve
95m1! water
5ml! The thus obtained negative-type photosensitive planographic print was passed through a transparent negative at a distance of 30 m using a 3KI4 metal halide lamp.
It was exposed to light for a second and developed using the following developer.

Benzyl alcohol 30- Jetanolamine 10g Sodium sulfite 5g Water 11
After washing with water, apply the burning pretreatment liquid used in Example 2,
After drying and performing burning treatment under the same conditions as in Example 2, I attached it to an offset printing machine and printed it, and a few sheets of beautiful prints were obtained from the beginning of printing, and when I continued printing as it was, it was almost the same as the beginning of printing. We were able to obtain 200,000 copies of printed matter that remained in good condition.

Example 7 The following photosensitive solution was applied to a plate that had been grained, anodized, and treated with sodium silicate in the same manner as in Example 6 to a dry weight of 3.
It was coated at a weight of 0 g/m' and dried at 100°C for 2 minutes.

3-Methyl-2-benzoylmethylenenaphtho(1-2-d) thiazole 5 g Phthalocyanine blue 3 g Ethylene dichloride 500 g 2-methoxyethyl acetate 500 g After drying, 3 g of polyvinyl alcohol
% by weight of the aqueous solution was applied to the surface of the photosensitive layer by dry weight.
g/m” and dried.

This plate was exposed and developed in the same manner as in Example 6. After washing with water, apply the burning pretreatment liquid used in Example 4,
After performing a burning process under the same conditions, the paper was attached to an offset printing machine and printed, and beautiful printed matter was obtained after just a few sheets.

Claims (1)

[Claims] In a plate-making method in which a photosensitive lithographic printing plate is subjected to image exposure and development and then subjected to a burning treatment, a condensation resin of an aromatic compound and an aldehyde, which is a condensation resin of an aromatic compound and an aldehyde, is added after development and before the burning treatment. A plate-making method characterized by applying an aqueous solution containing a condensation resin containing a compound or a salt thereof and performing a burning treatment in the presence of the compound.