JPH0432378B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to photosensitive lithographic printing plates.

Generally, a diazo resin obtained by condensation polymerizing a diazo compound with formaldehyde releases nitrogen through photolysis and loses its water solubility. Taking advantage of this property, it is widely used as a photosensitive material for making planographic plates for offset printing. In other words, when a water-soluble diazo resin is coated on a support (such as an aluminum plate) and exposed to light through a negative chip, the exposed areas become insoluble in water, and if this is developed with water,
A positive image is obtained on the surface of the support, which accepts fatty printing ink in the presence of fountain solution. Typical diazo resins include formaldehyde condensates of p-diazodiphenylamine.

Therefore, there are some plate-making materials in which only diazo resin is coated on the support.
30859, a diazo resin is reacted with an organic coupling agent or an inorganic coupling agent to produce an organic solvent-soluble diazo resin organic salt or a diazo resin inorganic salt, which is then combined with an organic solvent-soluble resin and a dye. A plate-making material in which a mixture is coated on a support is known.

Diazo resins, diazo resin organic salts, or diazo resin inorganic salts are relatively stable in a solid state, but when applied in a solution state or on a support,
Due to a dark reaction, it deteriorates within a few days,
Unexposed areas may not be easily developed, and non-surface line areas may become smudged.

In order to overcome these shortcomings in storage stability, attempts have been made to add phosphoric acid, citric acid, tartaric acid, etc. into the photosensitive layer, but no significant effects have been found in any of them.

The present invention solves the above-mentioned drawbacks and provides a photosensitive composition that does not cause stains in unexposed areas even after several months or even after several days under harsh conditions. is the following general formula (): [Wherein, X is hydrogen or a methoxy group, Z is a sulfonate, a carboxylate, PF ₆ , BF ₄ , SiF ₆
or an anion of SCN. ] A diazo resin organic salt or diazo resin inorganic salt derived from P-diazodiphenylamine or 3-methoxydiazodiphenylamine, and
The following general formula (): [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each the same or independently hydrogen atom, methyl group, hydroxyl group, alkoxyl group, sulfonic acid group, ammonium sulfonate group, carboxyl group, nitro group, or p
- indicates the sulfonic acid group of diazodiphenylamine. ] A photosensitive lithographic printing plate characterized by having a photosensitive layer containing 0.1 to 50% by weight of benzophenone and/or a benzophenone derivative represented by the following.

The diazo resin organic salt or diazo resin inorganic salt used in the present invention is
An acidic aromatic compound ( For example, benzene,
phosphinic, phosphonic, sulfonic, and carboxylic acid compounds of toluene and naphthalene;
and its derivatives), or aromatic compounds containing hydroxyl groups (e.g. 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid trihydrate) substances) or inorganic compounds (e.g.
Hexafluorophosphoric acid, hydroborofluoric acid, borofluoric acid, hydrosilicic acid, silicic boronic acid, potassium thiocyanate, sodium thiocyanate) were reacted to make them insoluble in water and soluble in organic solvents. It is something.

Examples of the organic solvent-soluble polymer compounds used in the present invention include epoxy resins, polybutyral resins, styrene-maleic anhydride copolymer resins, Sierrak resins, multi-component acrylic resins, and derivatives thereof, particularly those described in US Pat. No. 4,282,301. The acrylic resins described in . Moreover, the above-mentioned polymer compounds can be used alone or in combination of two or more.

Furthermore, in the present invention, a plasticizer and a dye can be added as necessary.

Dyes are added to make it possible to clearly distinguish between the support and the image area after development.Dye may cause color loss in the image area during development, or may cause problems with diazo photosensitive materials or organic polymer compounds. I don't like things that react. Therefore, preferred examples include Oil Blue #603 (Orient Chemical Industry Co., Ltd.).
), Victoria Blue BOH (Hodogaya Chemical Industry Co., Ltd.)
), Crustal Violet, Crustal Blue, Methylene Blue, Malachite Green, etc. can be used.

The benzophenone and its derivatives used in the present invention have the following general formula (): [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each the same or independently a hydrogen atom, a methyl group, a hydroxyl group, an alkoxyl group, a sulfonic acid group, an ammonium sulfonate group, a carboxyl group, a nitro group, or p-
Indicates the sulfonic acid group of diazodiphenylamine. ] As a specific example,
Benzophenone, methylbenzophenone, 2,4
-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone,
2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and its amine salt, 4-methyl-benzophenone-2-carboxylic acid, 3-nitro Examples include salts of -4-chlorobenzophenone-2-carboxylic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and diazodiphenylamine.

Paper, plastic film, zinc, copper, aluminum, stainless steel, or a composite material made of a combination of two or more of these can be used as a support to which the photosensitive composition of the present invention is applied. An aluminum plate whose surface is anodized can be suitably used.

The above photosensitive composition is prepared using an organic solvent such as methyl cellosolve, ethyl cellosolve, dimethyl formamide, dimethyl sulfoxide, methanol, methylene chloride, methyl cellosolve acetate, ethyl cellosolve acetate, etc. alone or in a mixture of two or more thereof. Dissolve the substance, apply the solution to a support, and dry.

For development, inorganic or organic alkalis, e.g.
An aqueous solution of sodium silicate, potassium silicate, caustic soda, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, etc. can be used as the developer, and it is preferable to further contain an anionic surfactant and an organic solvent.

Examples are shown below.

Example 1 Under a nitrogen stream, 0.3 g of azobisisobutyronitrile was added to 150 g of dioxane, heated to 80 to 85°C, and 50 g of 2-hydroxy-3-phenokipropyl acrylate and methyl methacrylate were added thereto.
A mixed solution of 25 g of acrylonitrile, 10 g of acrylonitrile, and 2 g of methacrylic acid was added dropwise with stirring. After finishing the dripping, 3
After stirring for an hour and adding 150g of dioxane,
The copolymer was precipitated by pouring it into water. The precipitate was filtered and dried at 40°C to obtain copolymer (1).

Next, a 1S (class 1 special grade) aluminum plate with a thickness of 0.25 mm is degreased by immersing it in a 10% caustic soda solution at 70°C for 10 seconds. Next, it was grained using a nylon brush, etched with a mixture of 5% caustic soda and 20% sodium phosphate at 70°C for 10 seconds, and washed with water. After that, anodic liquefaction was carried out for 2 minutes in a 10% sulfuric acid solution at a current density of 2A/ ^dm2 , and after washing with water,
A coating treatment was performed at 70° C. for 30 seconds with a 5% sodium silicate solution to produce an anodized aluminum plate (1).

Photosensitive solutions (A) and (B) having the following compositions were applied to the aluminum plate (1) and dried.

Composition of photosensitive solution (A) Methyl cellosolve 60g Copolymer (1) 15g Condensate of p-diazodiphenylamine and paraformaldehyde and dodecylbenzenesulfonate
1.5g Victoria Blue BOH 0.4g Add 1.0g of benzophenone to the above photosensitive solution (A) to make photosensitive solution (B). Aluminum plates (1) coated with photosensitive liquids (A) and (B) were placed on printing plates (A)-(1) and
It was set as (B)-1. Printed versions (A)-1 and (B)-1, respectively.
After being left in a constant temperature and humidity chamber at 45°C and 75% humidity for 5 days, the film was exposed through a negative film for 45 seconds at a distance of 1 m using a 2 K.W. high pressure mercury lamp. Next, it was immersed in a developer having the composition shown below at 25° C. for 1 minute, and then washed with water.

Composition of developer Sodium silicate 40% aqueous solution 5g Sodium isopropylnaphthalene sulfonate 2g Potassium sulfite 1g Phenyl glycol 5g Water 237g When printed as developed printing plates (A)-1 and (B)-1, the results were as follows. In plate (A)-1, stains occurred in the non-printing area of the printing surface, but in plate (B)-1
Good prints with no stains were obtained.

Example 2 Aluminum plate with a thickness of 0.25 mm and a width of 1000 mm (material
1100) was degreased with alkaline, washed with water, and then polished with a brush using an abrasive consisting of a 20% aqueous solution of carborundum. Next, remove the polishing residue thoroughly with a 10% caustic soda bath, wash with water, and then add 2.5% hydrochloric acid,
In an electrolytic solution (20℃) containing 0.1% sodium chloride,
AC electrolytic polishing was performed at a current density of 10 A/dm ² for 10 seconds. After that, it was washed with water and placed in a 10% sulfuric acid bath (30℃).
After anodizing for 60 seconds at a current density of 2 A/dm ² and washing with water, in a 5% potassium silicate bath (40°C).
AC anodizing treatment was performed again at a current density of 2 A/dm ² for 15 seconds, washed with water, and dried to obtain an anodized aluminum plate (2).

Apply the following photosensitive liquid to this aluminum plate (2),
Dry.

Composition of photosensitive solution (C) Methyl cellosolve 50g Dimethylformamide 10g Copolymer (1) 15g Potassium thiocyanate of a condensate of p-diazodiphenylamine and paraformaldehyde 1.5g Oil Blue #603 0.8g Photosensitive solution (C) ) and 1.5 g of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid amine salt was added to prepare a photosensitive solution (D). Aluminum plates (2) coated with photosensitive liquids (C) and (D) are placed on printing plates (C)-
2, (D)-2.

Printing plates (C)-2 and (D)-2 each at 45℃ and humidity 75
After leaving it in a constant temperature and humidity chamber for 5 days, Example 1
Exposure and development were carried out in the same manner. When printing was carried out using the developed printing plates (C)-2 and (D)-2, stains occurred in the non-printing areas of the printing plate (C)-2, but the printing plate (D)- In No. 2, good printing without stains was obtained.

Comparative Example The following photosensitive liquid (E) was applied to the anodized aluminum plate (2) produced in Example 2.

Composition of photosensitive solution (E) E) Methyl cellosolve 50g Dimethylformamide 10g Copolymer (1) 15g 2,2'4,4'-tetrahydroxybenzophenone, a condensate of p-diazodiphenylamine with paraformaldehyde Salt 1.5g Oil Blue #603 0.8g Add 10g of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid to the photosensitive solution (E) to prepare the photosensitive solution (F). The aluminum plates (2) coated with photosensitive liquids (E) and (F) were used as photosensitive printing plates (E)-2 and (F), respectively.
-2.

Photosensitive printing plates (E)-2 and (F)-2 were heated at 45℃, respectively.
After leaving it in a constant temperature and humidity chamber with a humidity of 75% for 3 days,
Exposure and development were carried out in the same manner as in Example 1. When printing was performed using the developed printing plates (E)-2 and (F)-2 as plates, stains occurred in the non-image areas of the printing plate (E)-2, but the printing plate (F) -2, good printed matter without stains was obtained.

In addition, when the photosensitive printing plate (E)-2 was left in a constant temperature and humidity bath under the same conditions as above for 5 days, Example 1
It could not be developed completely with the developer, and a residual film clearly remained, resulting in a solid stain when printed.

As described above, when a benzophenone derivative is added to a photosensitive composition consisting of a diazo resin organic salt and an acrylic copolymer, the long-term storage stability of the photosensitive lithographic printing plate made of the photosensitive composition is significantly improved. Ru.

As is clear from the above examples, the printing plate having the photosensitive layer of the present invention has good printing characteristics.

Claims (1)

[Claims] 1. The following general formula (): [Wherein, X is hydrogen or a methoxy group, Z is a sulfonate, a carboxylate, PF ₆ , BF ₄ , SiF ₆
or an anion of SCN. ] A diazo resin organic salt or diazo resin inorganic salt derived from P-diazodiphenylamine or 3-methoxydiazodiphenylamine, and
The following general formula (): [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each the same or independently a hydrogen atom, a methyl group, a hydroxyl group, an alkoxyl group, a sulfonic acid group, an ammonium sulfonate group, a carboxyl group, a nitro group, or p-
The sulfonic acid group of diazodiphelamine is shown. ] A photosensitive lithographic printing plate characterized by having a photosensitive layer containing 0.1 to 50% by weight of benzophenone and/or a benzophenone derivative represented by: