JP2596004B2 - Photosensitive lithographic printing plate - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a photosensitive lithographic printing plate, and more particularly to a negative type diazo photosensitive lithographic printing plate such as an offset plate, letterpress plate and gravure plate.

[Conventional technology]

A photosensitive material obtained by coating a photosensitive material in a thin film on a support is exposed through a transparent image to expose, and a difference in solubility is caused between an exposed portion and an unexposed portion, developed with an appropriate solvent, and developed on a photosensitive plate. Various techniques for forming a relief image have been proposed.
Heretofore, as a photosensitive composition used for such a purpose, a combination of a diazo compound and a polymer compound is well known in the case of a negative type lithographic printing plate.

Further, as the polymer compound used in combination with the diazo compound, a polymer compound having a functional group such as a hydroxyl group, an amino group, a cyano group, or a urethane group in the molecule is effective, for example, Japanese Patent Publication No. 57-43890. There is known a polymer compound having a phenolic hydroxyl group, for example, p-hydroxyphenyl (meth) acrylamide in a polymer structure described in Japanese Patent Application Laid-Open No. H10-260, 1988.

[Problems to be solved by the invention]

However, when the photosensitive composition containing these high molecular compounds used in combination with the diazo compound is applied to a metal plate, for example, an aluminum plate, and provided as a lithographic printing plate material, a phenolic hydroxyl group is used. When a polymer compound having the same is used, generally, the strength of the resist peculiar to the aromatic ring, that is, the improvement of the printing durability, the strength of the affinity of the printing ink, the strength of the resist to various printing chemicals, and the like are achieved. However, there is a drawback that poor development is likely to occur due to poor solubility in the developer.

In addition, conventional negative-type diazo photosensitive lithographic printing plates do not always have sufficient printability such as gum removal properties, recoverability of the entire solid stain after gum removal, or on-machine chemical resistance. Was desired.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, using a copolymer containing a methyl acrylate unit, preferably a specific amount, as a polymer compound, and performing an electrolytic etching treatment in a hydrochloric acid bath. It has been found that the intended object can be achieved by providing a photosensitive layer on an aluminum support, and the present invention has been completed.

That is, the gist of the present invention is that an aluminum support obtained by electrolytic etching in hydrochloric acid or an electrolytic solution containing hydrochloric acid as a main component is formed on an aluminum support. And (b) a photosensitive layer containing a copolymer containing, as a constituent unit, a structural unit having an aromatic hydroxyl group and a unit formed from methyl acrylate. Lithographic printing plates.

 Hereinafter, the present invention will be described in detail.

The diazo compound used in the present invention has a structural unit represented by the above general formula I.

For example, a diazo resin represented by a condensate of an aromatic diazonium salt and an active carbonyl-containing compound, particularly formaldehyde, is included, and among them, an organic solvent-soluble diazo resin is preferable.

Examples of the diazo resin include, for example, a diazo resin inorganic salt which is a reaction product of a condensate of p-diazodiphenylamine and formaldehyde or acetaldehyde with hexafluorophosphate and tetrafluoroborate, and a US Pat. No. 3,300,309, the condensate and a sulfonic acid such as paratoluenesulfonic acid or a salt thereof, a phosphinic acid such as benzenephosphinic acid or a salt thereof, a hydroxyl group-containing compound such as 2,4-dihydroxybenzophenone, Organic solvent-soluble diazo resin organic acid salts, which are reaction products such as -hydroxy-4-methoxybenzophenone-5-sulfonic acid or salts thereof.

Preferable examples include those containing a resin represented by the following general formula II, wherein n is 5 or more in the formula, in an amount of 20 mol% or more, preferably 20 to 60 mol%.

In the formula, R ⁵ , R ⁶ and R ⁷ represent a hydrogen atom, an alkyl group (eg, a methyl group, an ethyl group, etc.) or an alkoxy group (eg, a methoxy group, an ethoxy group, etc.), and R ⁸ represents a hydrogen atom, an alkyl group ( for example, a methyl group, an ethyl group or a propyl group), or a phenyl group, X represents a PF ₆ or BF _4,
n shows the number of 1-200.

The content of the diazo compound in the photosensitive composition forming the photosensitive layer according to the present invention is preferably 1 to 70% by weight, more preferably 3 to 60% by weight.

The polymer compound of the present invention is a copolymer containing (a) a structural unit having an aromatic hydroxyl group and (b) a unit formed from methyl acrylate as constituent components.

Examples of a monomer that provides a structural unit having an aromatic hydroxyl group include N- (4-hydroxyphenyl)-(meth) acrylamide and N- (2-hydroxyphenyl)
Monomers of (meth) acrylamides such as-(meth) acrylamide, N- (4-hydroxynaphthyl)-(meth) acrylamide; o-, m- or p-hydroxyphenyl (meth) acrylate monomers; o-, m- Or p-
Examples include, but are not limited to, hydroxystyrene monomers. Preferably, o-, m- or p
-Hydroxyphenyl (meth) acrylate monomer,
N- (4-hydroxyphenyl)-(meth) acrylamide monomer, more preferably N- (4-hydroxyphenyl)-(meth) acrylamide monomer.

The polymer compound of the present invention further comprises (c) a compound represented by the following general formula II
I (Wherein, R ⁹ represents a hydrogen atom or an alkyl group); (d) the following general formula IV (Wherein, R ¹⁰ represents a hydrogen atom, a methyl group or an ethyl group, and R ¹¹ represents an alkyl group or an alkyl-substituted aryl group having 2 to 12 carbon atoms).
It may be a copolymer with a structural unit having a carboxyl group, (f) a structural unit formed from styrenes, and the like.

As the monomer forming the structural unit of (c),
Acrylonitrile, methacrylonitrile, 2-pentenenitrile, 2-methyl-3-butenenitrile and the like are mentioned. Preferred are acrylonitrile and methacrylonitrile.

As the monomer forming the structural unit of (d),
Ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, amyl acrylate,
Hexyl acrylate, octyl acrylate, 2-chloroethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate and the like can be mentioned.

(E) Examples of the monomer forming the unit having a carboxyl group include methacrylic acid, acrylic acid, maleic anhydride, and maleic acid.

In addition, (f) styrenes include styrene, α-methylstyrene, methylstyrene, chloromethylstyrene, and the like.

In the present invention, in the polymer compound, the structural unit having an aromatic hydroxyl group needs to be contained in at least 1 mol%, and usually 1 to 50 mol%, preferably 5 to 30 mol%.
The unit formed from the methyl acrylate is contained in an amount of 5 mol% or more, usually 5 to 40 mol%, and preferably 10 to 30 mol%.

Other copolymer components are (c) 5 to 40 mol%, preferably 15 to 35 mol%, and (d) 25 to 60 mol%, preferably 35 to 35 mol%.
ホ 60 mol%, (e) 2-30 mol%, preferably 5-15 mol%
Mol% and (f) are 1 to 80 mol%, preferably 2 to 80 mol%.
It is suitable to select and use from the range of 50 mol%.

In the present invention, as a method for synthesizing a polymer compound in a photosensitive composition forming a photosensitive layer, there is a generally known radical polymerization method and the like, for example, an initiator such as azobisisobutyronitrile and benzoyl peroxide. (0.1 to 4.0 mol%) and is easily synthesized by a solution polymerization method.

As the molecular weight of the polymer compound, generally known gel permeation chromatography (hereinafter abbreviated as GPC)
Those having a weight average molecular weight in the range of 50,000 to 200,000, preferably 80,000 to 150,000 in terms of standard polystyrene comparative molecular weight by the method are used.

The content of the polymer compound in the photosensitive composition is preferably from 30 to 99% by weight, particularly preferably from 40 to 97% by weight, based on the whole composition.

In the present invention, a dye, a pigment, a coating improver, a plasticizer, and the like can be further added to the photosensitive layer, if necessary, in addition to the above-described materials.

Examples of the dye include Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Co., Ltd.), Oil Blue # 603, Patent Pure Blue, Crystal Violet, Brilliant Green, Ethyl Violet, Methyl Green,
Triphenylmethane, diphenylmethane represented by erythrosin B, basic fuchsin, malachite green, oil red, m-cresol purple, rhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, cyano-p-diethylaminophenylacetanilide, etc. And oxazine, xanthene, iminonaphthoquinone, azomethine and anthraquinone dyes.

Dyes are usually present in the photosensitive composition forming the photosensitive layer in an amount of about 0.
The content is 5 to about 10% by weight, preferably about 1 to 5% by weight.

Examples of the coatability improver include alkyl ethers (for example, ethyl cellulose and methyl cellulose), fluorine-based surfactants, and nonionic surfactants (for example, Pluronic L-64 (manufactured by Asahi Denka Co., Ltd.)). As plasticizers for imparting flexibility and abrasion resistance, for example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate , Trioctyl phosphate, tetrahydrofurfuryl oleate, oligomers of acrylic acid or methacrylic acid, and examples of the sensitizer for improving the lipophilic property of the image area include those described in JP-A-55-527. Half ester of styrene-maleic anhydride copolymer with alcohol And stabilizers such as polyacrylic acid, tartaric acid, phosphoric acid, phosphorous acid, and organic acids (acrylic acid, methacrylic acid, citric acid,
Oxalic acid, benzenesulfonic acid, naphthalenesulfonic acid, 4-methoxy-2-hydroxybenzophenone-5
-Sulfonic acid). The amount of these additives varies depending on the purpose of use, but is generally 0.01 to 30% by weight based on the total solid content.

In the present invention, the photosensitive lithographic printing plate of the present invention can be obtained by dissolving the photosensitive composition in a solvent capable of dissolving each of the above-mentioned components and applying and drying the solution on a specific support surface.

Hereinafter, a method for obtaining the lithographic printing plate material of the present invention using the above-described photosensitive composition will be described.

Examples of the solvent that can be used include methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, cellosolves such as ethyl cellosolve acetate, dimethylformamide, dimethylsulfoxide, dioxane, acetone,
Cyclohexanone, trichloroethylene, methyl ethyl ketone and the like can be mentioned. These solvents are used alone or in combination of two or more.

The coating method can be a conventionally known method, for example, spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating, or the like. The coating amount is preferably 0.15 to 10 g / m ² as a solid content.

The aluminum support to which the photosensitive composition is applied,
A solution subjected to electrolytic etching in hydrochloric acid or a bath containing hydrochloric acid as a main component is used.

Electrolytic etching treatment, the hydrochloric acid concentration 0.1% to 10%, an applied voltage 10～100V, current density 1~100A / dm ^2, a bath temperature of 10 to 50 ° C.,
It is preferable to perform the electrolysis for 3 to 3000 seconds.

After the electrolytic etching treatment, if necessary, a desmut treatment is carried out with an aqueous solution of an alkali or an acid to neutralize and wash with water, and usually an anodic oxidation treatment and a sealing treatment are carried out.

The anodizing treatment uses sulfuric acid, chromic acid,
The electrolysis is performed by using a solution containing one or more of oxalic acid, phosphoric acid, malonic acid and the like and using an aluminum plate as an anode. Anodized film amount formed is suitably 1 to 50 mg / dm ^2, preferably 10 to 40 mg / dm ^2, particularly preferably 25~40mg / dm ^2. The amount of anodized film can be measured, for example, by coating an aluminum plate with a chromic phosphate solution (phosphoric acid 85% solution:
l, Chromium (VI) oxide: 20g dissolved in 1 water
To dissolve the oxide film and measure the weight change before and after dissolution of the film on the plate.

Specific examples of the sealing treatment include boiling water treatment, steam treatment, sodium silicate treatment, and dichromate aqueous solution treatment. In addition, the aluminum plate support may be subjected to an undercoating treatment with an aqueous solution of a water-soluble polymer compound or a metal salt such as fluorinated zirconic acid.

In addition, in general, when a film original is closely adhered to a material of a photosensitive lithographic printing plate, baking is performed under vacuum, and a method for improving the vacuum adhesion can also be applied to the photosensitive lithographic printing plate of the present invention. it can. Methods for improving vacuum adhesion include a method of mechanically embossing the surface of the photosensitive layer, a method of spraying solid powder on the surface of the photosensitive layer, and a photosensitive layer as described in JP-A-50-125805. Examples thereof include a method of providing a mat layer on the surface, and a method of thermally fusing a solid powder to the surface of the photosensitive layer as described in JP-A-55-12974.

As the method of using the photosensitive lithographic printing plate of the present invention obtained as described above, a conventional method is applied. That is, by exposing through a transparent original image having a line image, a halftone dot image, and the like, and then developing with an aqueous developer, a negative relief image with respect to the original image is obtained. Light sources suitable for exposure include a carbon arc lamp, a mercury lamp, a xenon lamp, a metal halide lamp, and a strobe.

The developer used in the development of the photosensitive lithographic printing plate of the present invention may be any of known ones, but preferably the following are preferred. That is, the developer for developing the photosensitive lithographic printing plate of the invention contains a specific organic solvent, an alkali agent, and water as essential components. Here, the specific organic solvent is capable of dissolving or swelling the above-mentioned non-exposed portion (non-image portion) of the photosensitive composition layer when it is contained in a developing solution, and furthermore, water at normal temperature (20 ° C.) Solubility in
Refers to an organic solvent of 10% by weight or less. Such an organic solvent is only required to have the above-mentioned properties, and is not limited to the following. Examples thereof include, for example, ethyl acetate, propyl acetate, and acetic acid. Carboxylic acid esters such as butyl, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate, butyl levulinate; ketones such as ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone; ethylene glycol monobutyl ether, ethylene glycol benzyl ether; Alcohols such as ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbinol, n-amino alcohol, and methyl amyl alcohol; alkyl-substituted aromatic hydrocarbons such as xylene; methylene dichloride; Range chloride, and the like halogenated hydrocarbons monochlorobenzene and the like. Two or more of these organic solvents may be used. Among these organic solvents, ethylene glycol monophenyl ether and benzyl alcohol are particularly effective. Further, the content of these organic solvents in the developer is generally 1 to 20% by weight, and particularly preferable results are obtained when the content is 2 to 10% by weight.

On the other hand, examples of the alkaline agent contained in the developer include (A) sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium or ammonium salt of secondary or tertiary phosphoric acid, Inorganic alkaline agents such as sodium metasilicate, sodium carbonate, ammonia and the like (B) mono, di or trimethylamine, mono, di or triethylamine, mono or diisopropylamine, n
-Butylamine, mono, di or triethanolamine,
Organic compounds such as mono-, di- or triisopropanolamine, ethyleneimine, ethylenediamine and the like can be mentioned.

Preferred are (A) potassium silicate and sodium silicate, and (B) an organic amine compound, and particularly preferred are (A) potassium silicate and (B) di- or triethanolamine.

The content of these alkali agents in the developer is usually 0.1.
It is from 05 to 8% by weight, preferably from 0.5 to 6% by weight.

Further, in order to further improve the storage stability, printing durability, and the like, it is preferable to include a water-soluble sulfite in the developer as required. As such a water-soluble sulfite, an alkali or alkaline earth metal sulfite is preferable, and examples thereof include sodium sulfite, potassium sulfite, lithium sulfite, and magnesium sulfite. The content of these sulfites in the developer composition is usually 0.05 to 4% by weight, preferably 0.1 to 1% by weight.

In addition, a certain solubilizing agent may be included to assist the dissolution of the above-mentioned organic solvent in water. As such a solubilizer, in order to achieve the desired effect of the present invention,
Low-molecular-weight alcohol, which is more soluble in water than the organic solvent used,
It is preferable to use ketones. Further, an anionic activator, an amphoteric activator and the like can also be used. Such alcohols and ketones include, for example, methanol, ethanol,
It is preferable to use propanol, butanol, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methoxybutanol, ethoxybutanol, 4-methoxy-methylbutanol, N-methylpyrrolidone and the like. As the activator, for example, sodium isopropylnaphthalenesulfonate, sodium n-butylnaphthalenesulfonate, sodium N-methyl-N-pentadecylaminoacetate, sodium salt of lauryl sulfate and the like are preferable. The amount of these solubilizers such as alcohols and ketones to be used is not particularly limited, but is generally preferably about 30% by weight or less based on the whole developer.

The photosensitive lithographic printing plate of the present invention, after being imagewise exposed, is brought into contact with the above-mentioned developer or rubbed,
After about 10 to 60 seconds at about 10 ° C. to 40 ° C., the photosensitive composition in the unexposed areas is completely removed without adversely affecting the exposed areas of the photosensitive layer.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples.
The present invention is not limited to these examples.

Production of Aluminum Plate-1 An aluminum plate having a thickness of 0.24 mm is subjected to electrolytic polishing treatment in a 17 g / hydrochloric acid bath at a bath temperature of 25 ° C. and 50 A / dm ² for 25 seconds to obtain a grained plate having a maximum roughness of 4 μm. Was. The grained board was subjected to an anodic oxidation treatment in a 40% by weight phosphoric acid bath at a bath temperature of 35 ° C. at 3.2 A / dm ² for 20 seconds. Next, the anodized aluminum plate was immersed in a 1% by weight solution of sodium metasilicate at 90 ° C. for 30 seconds to perform a sealing treatment. Thereafter, washing with water and drying were performed to obtain an aluminum plate-1.

Manufacture of aluminum plate -2 A 0.24mm thick aluminum plate is coated with a nylon brush and 40
Use a 0 mesh pumicestone-water suspension, grain the surface, wash well with water and add 1% sodium hydroxide.
Immerse for 13 seconds in 40% phosphoric acid at 30 ° C with a current density of 4.0 A / dm ²
Anodize for 30 seconds, immerse in 1% sodium metaionate solution at 85 ° C for 3 minutes to perform sodium silicate treatment, then immerse in hot water at 90 ° C for 2 minutes, wash with water and dry -2.

Synthesis of diazo compound-1 14.5 g (50 mmol) of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under ice cooling. 1.5 g (50 mmol) of paraformaldehyde was slowly added dropwise to the reaction solution. At this time, the reaction was added so that the reaction temperature did not exceed 10 ° C. Thereafter, stirring was continued under ice cooling for 2 hours.

The reaction mixture was added dropwise to 500 ml of ethanol under ice cooling, and the resulting precipitate was removed. After washing with ethanol, this precipitate was dissolved in 100 ml of pure water, and a cold concentrated aqueous solution in which 6.8 g of zinc chloride was dissolved was added to this solution. The precipitate formed was washed with ethanol and dissolved in 150 ml of pure water. To this solution was added a cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved. The resulting precipitate was collected, washed with water, and dried at 30 ° C. for one day to obtain diazo compound-1.

When the molecular weight of this diazo compound-1 was measured by GPC, it was found that about 50 mol% of pentamers or more was contained.

Synthesis of diazo compound-2 Instead of 14.5 g of p-diazodiphenylamine sulfate,
3-methoxy-4-diazodiphenylamine sulfate 16.1
g (50 mmol) except that diazo compound-1
And diazo compound-2 was obtained.

Synthesis of Copolymer-1 Under a nitrogen stream, p-hydroxyphenylmethacrylamide 25 was added to a mixed solution of 100 g of acetone and 100 g of methanol.
g, acrylonitrile 15 g, methyl acrylate 25 g, ethyl acrylate 60 g, methacrylic acid 10 g, and azobisisobutyronitrile 5 g were dissolved, and the mixture was heated at 60 ° C. for 8 hours with stirring. After the completion of the reaction, the reaction solution was poured into water to precipitate a copolymer, followed by vacuum drying at 50 ° C. overnight. The weight average molecular weight of this copolymer-1 was 110,000 as measured by GPC.

Synthesis of Copolymers-2 to 4 Copolymer-1 except that the amount of each monomer and the like dissolved in the mixed solvent in synthesis of copolymer-1 was changed as shown in Table 1.
And copolymers having weight average molecular weights shown in Table 1 were obtained.

Examples 1 to 3 and Comparative Examples 1 to 5 A photosensitive solution having the composition shown in Table 2 was applied to the aluminum plate obtained as described above using a wheeler, and then dried at 85 ° C. for 3 minutes. Was obtained.

The obtained photosensitive lithographic printing plate was treated with a 3KW ultra-high pressure mercury lamp,
After exposure for 30 seconds from a distance of 00 cm, development was carried out at 25 ° C. for 45 seconds using a developer diluted with water. Table 4 shows the developing properties.

(Composition of developer) Benzyl alcohol 50g Triethanolamine 15g Sodium sulfite 5g Sodium butylnaphthalenesulfonate 25g Water 500g Also, among these, the lithographic printing plate developed at a dilution ratio of developer × 2 was used with a Heidelberg GTO printing machine. Printing on high-quality paper with general ink (Toyo Ultra King Red), printability (removability of gum, removal of solid stain after removal of gum,
When the on-machine chemical resistance was examined, the results shown in Table 4 were obtained. Table 4 also shows the solid sensitivity.

From Examples 1 to 3 and Comparative Examples 1 to 5, it is understood that the photosensitive lithographic printing plate of the present invention has relatively high sensitivity and gives results excellent in developability and printability.

〔The invention's effect〕

As described in detail above, the photosensitive lithographic printing plate of the present invention has high sensitivity and excellent developability and printability, so that the present invention has remarkable effects and is industrially extremely useful. is there.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Uehara 1 Sakuracho, Hino-shi, Tokyo Inside Shinko Konishi Shin Kogyo Co., Ltd. (72) Inventor Shinichi Matsubara 1 Sakuracho, Hino-shi, Tokyo Makoto Konishi Shinko (56) References JP-A-56-107237 (JP, A) JP-A-54-98614 (JP, A) JP-A-61-35995 (JP, A) JP-A-60-64352 (JP, A A) JP-A-62-71961 (JP, A) JP-A-62-125356 (JP, A)

Claims (1)

(57) [Claims] 1. An aluminum support obtained by electrolytic etching in hydrochloric acid or an electrolytic solution containing hydrochloric acid as a main component, comprising: And (b) a photosensitive layer containing a copolymer containing, as a constituent unit, a structural unit having an aromatic hydroxyl group and a unit formed from methyl acrylate. Photosensitive lithographic printing plate.