JPH04110853A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To improve the stability with lapse of time when this compsn. in used for a planographic printing plate and to lessen the decoloration of images by using an acidic dye as a coloring agent. CONSTITUTION:This compsn. is formed by incorporating an alkaline-soluble or swellable and film formable polymer (A), a diazo resin (B) and a coloring agent into the compsn. The acid dye is used for the coloring agent. A triphenyl methane acidic dye is preferably used for the acidic dye. Further, an addition polymerizable ethylenic unsatd. compd. and a photopolymn. initiator may be preferably incorporated therein. A polymer of the formula, etc., are usable for the component A and the hexafluorophosphate of the condensation product of 4-diazodiphenyl amine and parafomaldehyde is usable for the component B.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a negative photosensitive composition,
In particular, it relates to a photosensitive composition used in a photosensitive lithographic printing plate. More specifically, we are developing a photosensitive lithographic printing plate that has good stability over time and also improves color fading in the image area during cleaning of the lithographic printing plate and printing with ultraviolet curable ink. This invention relates to the photosensitive composition used.

[Conventional technology]

Conventionally, photosensitive diazo compounds have been widely used as photosensitive compositions for lithographic printing plates, and are broadly divided into negative type, in which exposed areas become insolubilized in a developer upon irradiation with light, and negative types, in which exposed areas become soluble in light irradiation. There is a positive type.

As negative photosensitive diazo compounds, diazo resins typified by condensates of 4-diazodiphenylamine and formaldehyde are commonly used.

In some cases, such diazo resin is mixed with a binder resin, an ethylenically unsaturated compound capable of addition polymerization, etc. to form a photosensitive composition, which is then used to form an aluminum plate that has been subjected to surface treatments such as roughening and anodizing. Photosensitive lithographic printing plates made by coating on supports such as the following are widely used. A negative film is passed through this photosensitive lithographic printing plate, imagewise exposed to actinic rays to cure the exposed areas, and then the unexposed areas are removed with a suitable developer to expose the hydrophilic surface of the support, and the lithographic printing plate becomes. This lithographic printing plate is produced by an offset printing machine.
Printing takes advantage of the hydrophilicity of unexposed areas and the lipophilicity of exposed areas.

At this time, a pigment such as a dye or a pigment is contained in the photosensitive composition in order to visualize the image area during development or printing. Examples of dyes include basic oil-soluble dyes such as crystal violet, malachite green, Victoria blue, methylene blue, ethyl violet, and rhodamine B; commercially available products include, for example, Victoria Pure Blue BOHJ (manufactured by Hodogaya Chemical Industry Co., Ltd.); ), “
Oil Blue #603J (Orient Chemical Industry■
company), etc.

[Problems to be Solved by the Invention] However, these conventionally used dyes cannot be used when printing with ultraviolet curable ink if the plate surface is repeatedly cleaned with a plate cleaner containing organic solvents, surfactants, etc. during printing. When cleaning the plate surface with washing oil or washing oil, dye elution (color loss) from the photocured image area occurs, resulting in a decrease in image density and difficulty in identifying the resist image, which poses a practical problem. Ta. Furthermore, addition of these dyes also tended to reduce the stability of photosensitive planographic printing plates over time.

In addition, in the case of pigments, color fading is less likely to occur, but since they are insoluble in the organic solvent used when applying the photosensitive composition, the coating properties are not sufficient because they are dispersed, and they are essentially insoluble. Therefore, it did not dissolve in a developer and its developability was insufficient.

The problem to be solved by the present invention is to solve the above-mentioned drawbacks,
The object of the present invention is to provide a photosensitive composition that provides images with improved color loss and also has good stability over time.

Another problem to be solved by the present invention is to provide a photosensitive composition that can be suitably used in the photosensitive layer of a photosensitive lithographic printing plate.

[Means to solve the problem]

The present invention comprises (a) an alkali-soluble or swellable, bulky, film-forming polymer, (b) a diazo resin, and (c
) The above problem was solved by using an acid dye as the colorant in a photosensitive composition containing a colorant.

The present invention will be specifically explained below.

The alkali-soluble or swellable and film-formable polymer used in the present invention includes carboxyl groups,
It is a polymer having alkali-soluble groups such as phenolic hydroxyl groups and sulfonamide groups, and has a weight average molecular weight of 2.0.
A range of 00 to 200,000 is preferred.

Examples of polymers having carboxyl groups include (meth)acrylic acid [acrylic acid and methacrylic acid are hereinafter collectively referred to as (meth)acrylic acid. ]-(meth)acrylic acid ester copolymer, hydroxyalkyl (meth)acrylate described in Japanese Patent Publication No. 55-34929-(
Meth)acrylic acid-(meth)acrylonitrile copolymer, 2-hydroxy-3-phenoxypropyl (meth)acrylate described in Japanese Patent Publication No. 57-51656 and (
Copolymers with meth)acrylic acid, partially esterified maleic acid copolymers, copolymers with ethylenically unsaturated bonds and carboxyl groups in the side chains (for example, some vinyl copolymers containing carboxyl groups, Added oxirane ring-containing ethylenically unsaturated compound; copolymer of allyl (meth)acrylate and (meth)acrylic acid), cyclic acid anhydride adduct of polyvinyl acetal resin, having a carboxyl group in the side chain Polyurethane resin, polyurethane resin with ethylenically unsaturated bonds and carboxyl groups in the side chain,
Examples include polyester resins having carboxyl groups in side chains, polyester resins having ethylenically unsaturated bonds and carboxyl groups in side chains, and the like.

As the polymer having a phenolic hydroxyl group, for example, a polymer of N-(4-hydroxyphenyl) methacrylamide described in Japanese Patent Publication No. 57-43890 or a copolymer with other copolymerizable hetamines, Examples include novolac resins, polyester resins having phenolic hydroxyl groups in side chains, and the like.

Other polymers with alkali-soluble groups include:
-SO□NH2 described in JP-A-1-227142
Copolymer having a group in the side chain; Copolymer having a 18O□NH- group in the side chain described in JP-A-1-231043; -CONHC as described in JP-A 1-284849
Copolymer having O-group in side chain; JP-A-63-2613
-CONISO□- group, -NHCO described in Publication No. 50
Examples include polyurethane resins having NISO□- groups, -CONHSO□NH groups, and the like.

Examples of the diazo resin 7 include diazo resins typified by salts of condensates of diazodiarylamine and active carbonyl compounds, and those that are photosensitive, water-insoluble, and soluble in organic solvents are preferred.

Particularly suitable diazo resins include 4-diazodiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-4'-methyldiphenylamine, 4-diazo-3'
-Methyldiphenylamine, 4-thiazo4'-methoxydiphenylamine, 4-diazo-3-methyl-4'-
Ethoxydiphenylamine, 4-diazo-3-methoxydiphenylamine, etc. and formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, 4.
It is an organic or inorganic acid salt of a condensate with 4'-bis-methoxymethyldiphenyl ether or the like.

Examples of organic acids include methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, mesitylenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, propylnaphthalenesulfonic acid, 1-naphthol-5-sulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 2-
Hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,4-dihydroxybenzophenone, benzenephosphinic acid, etc. are mentioned, and the inorganic acids include hexafluorophosphoric acid, tetrafluoroboric acid, thiocyanic acid, etc.

Furthermore, a diazo resin whose main chain is a polyester group described in JP-A-54-30121; JP-A-61-2735;
A diazo resin obtained by reacting a polymer having a carboxylic acid anhydride residue described in Publication No. 38 with a diazo compound having a hydroxyl group; a diazo resin obtained by reacting a polyisocyanate compound with a diazo compound having a hydroxyl group, etc. Can be used.

The amount of these diazo resins used is preferably in the range of 1 to 40% by weight based on the solid content of the composition, and two or more types of diazo resins may be used in combination, if necessary.

The colorant used in the present invention is an acid dye. Acidic dyes are those whose pigment components become anions in an aqueous solution.
It contains sulfonic acid groups, phosphoric acid groups, carboxyl groups, phenolic hydroxyl groups, etc., and these form salts with base components.

Acidic dyes include triphenylmethane, diphenylmethane, azo, anthraquinone, xanthine,
Oxazine-based, azine-based, quinoline-based, nitro-based, thiazole-based, etc. are listed, and the skeletons of these acidic dyes have been known for a long time [Dye Handbook: Organic Synthetic Chemistry Association Line], ``Color Index J, etc. Among them, Acid Blue 1,
Triphenylmethane acid dyes such as Acid Blue, Acid Blue 9, Acid Blue 83, Acid Blue 90, Acid Blue 103, and Acid Blue 104 are preferred.

The amount of acid dye added is 0.05 based on the solid content of the composition.
The range of IO to IO weight % is preferable, and the amount added may be adjusted depending on the thickness of the photosensitive layer and image density.

In the present invention, an acid dye is used as a colorant component, but
If necessary, other dyes and pigments can be used in combination, and the amount used is 70% by weight or less, more preferably 50% by weight or less, based on the total weight of the colorant.

Other dyes include, for example, JP-A-50-138905
No. 56-121031, Japanese Patent Application Laid-Open No. 1983
-Crystal violet, methyl violet 2B, malachite green, tsuksin, balatushin, rhodamine B, as described in Publication No. 222842,
Victoria Blue B, Victoria Pure Blue BOH,
Brilliant Green, Night Blue BX, Neutral Red, Rosuline Pure Blue 3G, Oil Blue #603, Victoria Pure Blue BOH p-toluenesulfonate, Crystal Violet p-)luenesulfonate, Oil Blue #603-2 -Hydroxy-4-methoxybenzophenone-5-sulfonate and the like.

The photosensitive composition of the present invention can contain an ethylenically unsaturated compound capable of addition polymerization and a photopolymerization initiator.

Addition-polymerizable ethylenically unsaturated compounds are monomers or oligomers having a boiling point of 100°C or higher at normal pressure and having at least one, preferably two or more addition-polymerizable ethylenically unsaturated groups in one molecule. It is. Examples of such monomers or oligomers include polyethylene glycol mono(meth)acrylate [hereinafter, methacrylate and acrylate are collectively referred to as (meth)acrylate. monofunctional (meth)acrylates such as polypropylene glycol mono (meth)acrylate, phenoxyethyl (meth)acrylate; polypropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, Neopentyl glycol di(
meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, hexanediol di(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, polyhydric alcohol (Meth)acrylate of alkylene oxide adduct, (meth)acrylate of polyhydric phenol/alkylene oxide adduct, Tokuko Sho 4
No. 8-41708, Japanese Patent Publication No. 50-6034, Japanese Patent Publication No. 5
Urethane acrylates described in each publication No. 1-37193, JP-A No. 4864183, JP-A No. 49-4
Examples thereof include polyfunctional (meth)acrylates such as polyester acrylates and epoxy acrylates to which an epoxy resin and (meth)acrylic acid are added, which are described in Japanese Patent Publication No. 3191 and Japanese Patent Publication No. 52-30490.

The amount of these addition-polymerizable ethylenically unsaturated compounds used is preferably in the range of 0 to 70% by weight based on the solid content of the composition.

As a photopolymerization initiator, for example, US Pat. No. 236766
α-carbonyl compounds described in US Pat. No. 1, acyloin ethers described in US Pat. No. 2,448,828, and α-hydrocarbon-substituted aromas described in US Pat. No. 2,722,512. Group acyloin compounds, polygroup quinone compounds described in U.S. Pat. No. 3,046,127, U.S. Pat. No. 3,549,367
The combination of triarylbiimidazole and p-aminophenyl ketone described in U.S. Pat. No. 42
Trihalomethyl- as described in No. 39850
3-) Riazine compounds, oxadiazole compounds described in U.S. Pat. No. 4,212,970, acridine and phenazine compounds described in U.S. Pat. No. 3,751,259, Japanese Patent Publication No. 51-48516
Examples include benzothiazole compounds described in the above publication, and the amount used is 0 to 2 based on the solid content of the composition.
A range of 0% by weight is preferred.

In addition, the photosensitive composition of the present invention has an alkali-soluble or swellable film-forming polymer.
Other alkali-insoluble polymers can also be used in an amount of up to 0% by weight. Examples of such polymers include acrylic resins, polyamide resins, polyurethane resins, epoxy resins, polyacetal resins, polystyrene resins, and polyester resins.

Furthermore, in order to improve performance, known additives such as thermal polymerization inhibitors, surfactants, plasticizers, stability improvers, etc. can be added.

Examples of the surfactant include anionic surfactants,
Examples include nonionic surfactants and fluorine surfactants.

Examples of the plasticizer include diethyl phthalate, dibutyl phthalate, dioctyl phthalate, fributyl phosphate, trioctyl phosphate, tricresyl phosphate, tri(2-chloroethyl) phosphate, and tributyl citrate.

Further, known stability improvers such as phosphoric acid, phosphorous acid, oxalic acid, tartaric acid, malic acid, citric acid, dipicolinic acid, polyacrylic acid, benzenesulfonic acid, toluenesulfonic acid, etc. can also be used in combination.

The amount of these various additives to be added varies depending on the purpose, but is generally preferably in the range of 0 to 30% by weight of the solid content of the photosensitive composition for lithographic printing plates of the present invention.

Further, it is dissolved in a suitable coating solvent to prepare a photosensitive composition.

Examples of such coating solvents include methylene chloride,
Halogenated solvents such as chloroform, dichloroethane, trichloroethane, trichloroethylene, monochlorobenzene, dichlorobenzene, carbon tetrachloride, etc.; hexane,
Aliphatic or alicyclic or aromatic hydrocarbon solvents such as heptane, cyclohexane, benzene, toluene, xylene, etc.; ether solvents such as tetrahydrofuran, dioxane, diethyl ether, ethyl propyl ether, dibutyl ether, ethylene glycol dimethyl ether, etc.; Glycol methyl ether acetate, glycol ethyl ether acetate, methyl acetate, ethyl acetate,
Ester solvents such as butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-methyl-4-methoxy-2-pentanone; methanol, ethanol, propatool, butanol, tetrahydrofurfuryl alcohol , benzyl alcohol, diacetone alcohol, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, ethylene glycol monophenyl ether,
Alcohol solvents such as cyclohexanol; nitrogen-containing solvents such as acetonitrile, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and nitrobenzene; dimethyl sulfoxide, etc. The above solvents may be used alone or in combination of two or more. You can also
In some cases, a mixed solvent with water may also be used.

The photosensitive composition thus produced is applied to a support by a well-known coating method such as dip coating, curtain coating, roll coating, spray coating, whirler coating, spinner coating, air knife coating, doctor knife coating, etc. .

Examples of the support include metal plates such as aluminum, zinc, copper, stainless steel, and iron; plastic films such as polyethylene terephthalate, polycarbonate, polyvinyl acecool, and polyethylene; paper coated with melt-coated synthetic resin or synthetic resin solution; Examples include composite materials in which a metal layer is provided on a plastic film by techniques such as vacuum deposition and lamination; and various other materials used as supports for printing plates. In addition, in the case of a support with a metal surface, especially aluminum, graining treatment,
It is preferable that a surface treatment such as anodizing treatment or hydrophilic treatment is performed. The coating amount is typically 0.5 to about 5 g/nf on a dry weight basis.

After coating, it is dried by a well-known method to obtain a photosensitive lithographic printing plate having a photosensitive layer provided on the support.

The photosensitive layer of this photosensitive lithographic printing plate is made of a polymer with excellent oxygen barrier properties, such as polyvinyl alcohol or acidic cellulose, in order to completely prevent the polymerization inhibition effect caused by oxygen in the air. A protective layer may also be provided. The photosensitive layer of this photosensitive lithographic printing plate is subjected to imagewise exposure using a negative image to harden and insolubilize the exposed portions of the photosensitive layer, and then developed with an aqueous alkaline developer to dissolve the unexposed portions. A lithographic printing plate with a corresponding image formed thereon is obtained.

Suitable light sources used for exposure include, for example, carbon arc lamps, mercury lamps, metal halide lamps, xenon lamps,
Examples include chemical lamps and lasers.

Examples of the aqueous alkaline developer include sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, and sodium metasilicate. Examples include aqueous solutions containing alkaline agents such as sodium carbonate, aqueous ammonia, monoethanolamine, jetanolamine, triethanolamine, diisopropanolamine, monomethylamine, dimethylamine, and triethylamine. Furthermore, the solubility of the unexposed part of the photosensitive layer,
For the purpose of improving the permeability of the developer, anionic surfactants such as isopropylnaphthalene sodium sulfonate, dodecylbenzenesulfonic acid sodium, sodium salt of lauryl alcohol sulfate, and dialkylsulfosuccinate; benzyl alcohol, N-benzylethanolamine, Solvents such as phenoxyethanol, diacetone alcohol, methyl cellosolve, isopropyl alcohol, etc. can also be added.

The photosensitive composition of the present invention is useful as a photosensitive composition for lithographic printing plates, but is not necessarily limited to this use, and can be used for resin letterpress plates, screen printing plates, photoresists, color proofs, etc. It can also be used as a hologram forming material.

As mentioned above, the present invention will be specifically explained using Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Examples 1 to 3, Comparative Example 1 (1) Creation of photosensitive planographic printing plate After degreasing an aluminum plate with a thickness of 0.24 mm with dibasic sodium phosphate solution, electrolytically etching it in a 1% aqueous hydrochloric acid solution. The surface was roughened, and then anodized in a 20% sulfuric acid aqueous solution at a current density of 2 A/d, and 2.5 g
/n? An oxide film was formed. Thereafter, it was immersed in a 3% aqueous solution of No. 3 sodium silicate at 60° C. for 1 minute, washed with water and dried to obtain a support.

Coat photosensitive liquid 1 on this support with a roll coater,
A photosensitive lithographic printing plate was obtained by drying at 00°C for 3 minutes. At this time, the dry coating weight was 2.2 g/rd.

/ Photosensitive liquid-1 *1) The binder resin number had a composition shown by the following formula and a weight average molecular weight of 70,000.

1. Exposure was carried out using a metal halide lamp (Idolfin 100OJ manufactured by Iwasaki Electric Co., Ltd.) for an exposure time of 5 steps of photosensitivity.Then, the developer was heated at 25°C with the developer described below.
A lithographic printing plate was obtained by developing for a minute.

Developer *2) Diazo resin is a hexafluorophosphate salt of a composite of 4-diasodiphenylamine and paraformaldehyde.

*3) The type of colorant and its addition amount x gL, see Part 1 below.
Shown in the table.

(2) Preparation of lithographic printing plate Photosensitive lithographic print obtained in (1)! Output*4 with a halftone dot image film and a 0.15 step wedge attached to the 11th plate and placed 1m away from this.
) [Perex NBLJ is a sodium alkylnaphthalene sulfonate-based anionic surfactant manufactured by Kao ■.

(3) Evaluation of photosensitive lithographic printing plates and lithographic printing plates The evaluation results for the stability over time of the photosensitive lithographic printing plates and color fading of the lithographic printing plates are summarized in Table 1.

Each test condition is shown below.

- Stability over time: Photosensitive lithographic printing plate at 50°C and humidity 75%
It was stored for 3 days under these conditions, and then exposed and developed under the same conditions as above. The presence or absence of scumming due to printing ink in non-image areas and developability were evaluated by comparing with those exposed and developed immediately after manufacturing the photosensitive lithographic printing plate.

- Color loss of the lithographic printing plate was evaluated using a cleaner immersion test. Immersion test: UV curing ink (
Daicure roller cleaning oil (Dainippon Ink & Chemicals), a cleaner used in printing with UV ink (abbreviated as UV ink)
The lithographic printing plate obtained by exposure and development was immersed for 3 hours in a lithographic printing plate (manufactured by Co., Ltd.) for 3 hours, and the ratio of the reflection density of the image area after the test to the reflection density of the image area before the test was measured. This ratio is 90°
A score of C or higher was considered good, and a score of less than 90% was considered poor.

/ / Examples 4 to 6, Comparative Example 2 (1) Preparation of photosensitive planographic printing plate Photosensitive liquid-2 was applied to the support using a roll coater, and 1
A photosensitive lithographic printing plate was obtained by drying for 3 minutes at 00''C. At this time, the dry coating weight was 2.2 g/rrr.

Photosensitive liquid-2 *6) Polyester resin is an acid synthesized from succinic anhydride/ethylene oxide (2.2 mol) adduct of bisphenol A (1 mol)/glycerol-α-acryether/pyromellitic dianhydride. It is a polyester resin having a value of 52.5 and an allyl group concentration of 0.91 meq/g resin in a 40% by weight dioxane solution.

*7) The urethane acrylate resin is an adduct of "Millione" MR (manufactured by Nippon Polyurethane Industry ■, MDI polyisocyanate) and pentaerythritol triacrylate.

*8) Diazo resin is p-toluenesulfonate, which is a condensate of 4-diazodiphenylamine and paraformaldehyde.

*9) The types of colorants and their added amounts x g are shown in Table 2 below.

(2) Preparation of lithographic printing plate A lithographic printing plate was obtained in the same manner as in Example 1.

(3) Evaluation Example 1 of photosensitive lithographic printing plates and lithographic printing plates
The same evaluation was conducted and the results are summarized in Table 2.

〔Effect of the invention〕

The photosensitive composition of the present invention has good stability over time when used as a photosensitive lithographic printing plate, and is also resistant to washing of the plate when printing as a lithographic printing plate and ultraviolet curable ink. Color loss in image areas during printing is improved.

Claims (1)

[Scope of Claims] 1. A photosensitive composition containing (a) an alkali-soluble or swellable polymer capable of forming a film, (b) a diazo resin, and (c) a colorant, wherein the colorant is an acid dye. A photosensitive composition characterized by: 2. The photosensitive composition according to claim 1, wherein the acid dye is a triphenylmethane acid dye. 3. The photosensitive composition according to claim 1 or 2, further comprising an ethylenically unsaturated compound capable of addition polymerization and a photopolymerization initiator.