JPS626253A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To obtain a photosensitive composition capable of effectively preventing oxygen effect at the time of imagewise exposure even if an oxygen blocking layer is not formed on the surface of a photosensitive layer and obtaining a lithographic plate high in printing resistance by using an alkali- soluble or swellable polymer capable of film-forming made of an acidic vinyl copolymer. CONSTITUTION:The photosensitive composition is composed of an ethylenically unsaturated polymerizable compound, an alkali-soluble or -swellable polymer capable of forming a film, a photopolymerization initiator, and an diazo resin. Said alkali-soluble or -swellable polymer capable of forming a film is an acidic vinyl copolymer comprising (A) structural units each having an allyl group on the side chain, and (B) structural units having an NC or OH group on the side chain, and it is preferred to contain (A) in an amount of 20-80mol%, especially, 50-80mol%, and (B) in an amount of 70-10mol%, especially, 40-10mol%, and if (A) is <=20mol%, curing is not made sufficient by photopolymerization, and when it is used as the photosensitive layer of the lithographic plate, high printing resistance can not be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photosensitive composition suitable for producing a photosensitive lithographic printing plate. More specifically, the present invention relates to a novel photopolymerizable photosensitive composition that reduces the influence of acid buildup during plate making.

[Conventional technology]

Attempts have been made to use photopolymerizable compositions as photosensitive imaging layers suitable for photosensitive lithographic printing plates.

For example, Japanese Patent Publication No. 46-32714 discloses a basic composition consisting of an organic solvent soluble polymer, an ethylenically unsaturated addition polymerizable compound, and a photopolymerization initiator;
No. 34041 discloses a composition in which unsaturated double bonds are introduced into an organic solvent-soluble polymer to improve curing efficiency.

Special Publication No. 48-38403, Special Publication No. 53-27605
No. 4 and British Patent No. 1,388,492, compositions using novel photopolymerization initiators are described, and some of them have been put to practical use, but none of the photosensitive compositions are suitable for lithographic printing. When used as a photosensitive layer of a printing plate, there is a drawback that polymerization is significantly inhibited by oxygen during image exposure, and an oxygen-blocking layer made of a water-soluble resin must be provided on the surface of the photosensitive layer. Therefore, attempts have been made to add a diazo resin having a negative effect to the above-mentioned photopolymerizable composition in order to reduce the influence of oxygen on polymerization inhibition. The technique of adding this diazo resin is known, for example, from Japanese Patent Application Laid-Open No. 59-20
No. 6825, JP-A-59-53836, JP-A-51-
178449, Japanese Patent Application Laid-Open No. 57-196230, and US Pat. No. 4,316,949, these methods have not yet been said to have sufficient effects.

Furthermore, in JP-A-59-53835, (i)
A photosensitive composition comprising an ethylenically unsaturated addition polymerizable compound, (ii) a vinyl copolymer having an allyl group in its side chain, (iii) a photopolymerization initiator, and (iv) a negative-acting diazo resin is disclosed. However, it could not be said that it had a sufficient effect.

[Problem that the invention seeks to solve]

Therefore, an object of the present invention is to obtain a photosensitive composition that can effectively prevent the influence of oxygen during image exposure without providing an oxygen barrier layer on the surface of the photosensitive layer, and that can provide high printing durability in planographic printing plates. shall be.

[Means for solving problems]

The present invention provides a photosensitive composition disclosed in JP-A No. 59-53835, in which the component (ii) is a vinyl copolymer containing, in particular, a structural unit having an allyl group in its side chain;
2) This was done based on the knowledge that a photosensitive plate with significantly reduced effects of oxygen can be obtained by using an acidic copolymer containing a structural unit having an IJ group and/or a hydroxyl group in its side chain. be.

That is, the present invention comprises (1) an ethylenically unsaturated polymerizable compound, (2) a polymer that is soluble or swellable in alkaline water and capable of forming a film, (3) a photopolymerization initiator, and (4) a diazo resin. In the photosensitive composition, an alkaline water-soluble or swellable and film-forming polymer (
Provided is a photosensitive composition characterized by being an acidic vinyl copolymer containing A) a structural unit having an allyl group in its side chain; and (B) a structural unit having a nitrile group and/or a hydroxyl group in its side chain. do.

The present invention uses a specific polymer having the above two types of structural units (A) and (B) in the molecule as the alkaline water-soluble or swellable and film-formable polymer of component (2). It is characterized by In other words, JP-A-59
A vinyl copolymer having a simple allyl group in the side chain as described in No. 53836 is not photocured by a negative working diazo resin, but a nitrile group and/or hydroxyl group is added to the side chain in this copolymer. This is because by introducing the structural unit having the diazo resin, photocuring with the diazo resin occurs, and image formation becomes possible even in the presence of oxygen. Furthermore, by adding an ethylenically unsaturated polymerizable compound and a photopolymerization initiator to these compositions, crosslinking by photopolymerization and crosslinking by diazo resin are performed simultaneously, and image formation is possible even in the presence of oxygen. It made it possible.

Note that the polymer that is soluble or swellable in alkaline water and capable of forming a film is defined as a film having a thickness of approximately 1 μm.
Dissolves or swells by 165 times or more in volume when immersed in a layer weight% (hereinafter abbreviated as %) aqueous sodium hydroxide solution containing 0% by weight or less of an organic solvent (for example, benzyl alcohol) at room temperature for about 5 minutes. refers to a polymer that

The acidic copolymer of component (2) of the present invention is composed of (i) a structural unit having a nitrile group and/or a hydroxyl group in its side chain, and a structural unit having a carboxylic acid, a carboxylic acid halide, or a carboxylic acid anhydride in its side chain. ('i
i) 2) Vinyl monomers having an IJ group and/or hydroxyl group in the side chain, vinyl monomers having an allyl group in the side chain, and vinyl monomers having an acidic group such as carboxylic acid or sulfonic acid in the side chain. Examples include those whose bodies are multi-component copolymerized. The structural unit (B) having a nitrile group and/or a hydroxyl group in its side chain is obtained by copolymerizing a vinyl monomer having a nitrile group and/or a hydroxyl group in its side chain. Specifically, such vinyl monomers include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, butylene glycol mono(meth)acrylate, hexamethylene glycol (
meth) acrylate, polyethylene glycol (meth)
Acrylate, polypropylene glycol mono(meth)
Examples include acrylate, N-hydroxyphenyl (meth)acrylamide, (meth)acrylonitrile, cyanoethoxyphenyl (meth)acrylamide, and cyanoethyl (meth)acrylate. Examples of allyl compounds having a hydroxyl group, an amino group, a glycidyl group, or an isocyanate group in their side chains include allyl alcohol, allyl glycidyl ether, and compounds represented by the general formula [1-a, :l described in JP-A No. 59-53836. etc. can be given. Vinyl monomer (A) having an allyl group in its side chain
As for the allyl compound having the above-mentioned hydroxyl group, amino group, glycidyl group, or isocyanate group in the side chain and (meth)
Examples include those synthesized by condensation reactions with acrylic acid, itaconic acid, crotonic acid, and maleic acid.

Examples of the vinyl monomer having a carboxylic acid group or a sulfonic acid group in its side chain include (meth)acrylic acid, itaconic acid, crotonic acid, itaconic anhydride, maleic anhydride, and vinylbenzenesulfonic acid.

The structural unit (A) having an allyl group in its side chain in the acidic vinyl copolymer is preferably from 20 to 80 mol%, and more preferably from 50 to 80 mol%. If the amount is less than 20 mol %, curing by photopolymerization is insufficient, and high printing durability cannot be obtained when used as a photosensitive layer of a lithographic printing plate. Moreover, the structural unit (B) having a nitrile group and/or a hydroxyl group in the side chain is 70 to
It is preferably 10 mol%, more preferably 40-10 mol%. If it is less than 10 mol %, photocuring with the diazo resin will not be sufficient, and the effect of oxygen during exposure will be significant, and if the degree of vacuum in the exposure machine is incomplete, sensitivity will decrease. The acid content in the copolymer has an acid value of 10 to 200, preferably 20 to 1.
The range is 50. If the acid value is less than 10, the solubility in alkaline water will be poor, which is not preferable.

Further, an acid value of 200 or more is not preferable because the cured photosensitive layer has a high swelling property in alkaline water.

Among these acidic vinyl copolymers, allyl (meth)acrylate/(meth)acrylic acid/hydroxyethyl methacrylate, cyanoethyl (meth)acrylate, or cyanoethoxyphenylacrylamide copolymers are most preferred.

The ethylenically unsaturated polymerizable compound, which is component (1) of the present invention, has a boiling point of 100°C or higher at normal pressure, and has at least one, more preferably two or more addition-polymerizable unsaturated molecules in one molecule. A monomer or oligomer having a molecular weight of 10,000 or less is preferred. Specifically, such monomers are oligomers such as monofunctional acrylates and methacrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and phenoxyethyl(meth)acrylate; polyethylene glycol di(meth)acrylate , polyethylene glycol di(meth)acrylate, trimethylolethane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate Acrylate, hexanediol di(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, polyhydric alcohols such as glycerin and trimethylolethane added with ethylene oxide or propylene oxide and then converted into (meth)acrylate, Tokkosho No. 48-41708, Special Publication 1977
Urethane acrylates as described in the specifications of JP-A-6034 and JP-A-51-37193;
Polyester acrylates, epoxy acrylates prepared by reacting an epoxy resin with (meth)acrylic acid, etc. described in Japanese Patent Publication No. 8-64183, Japanese Patent Publication No. 49-43191, and Japanese Patent Publication No. 3.0490 of 1982 Examples include polyfunctional acrylates and methacrylates. For more details, see Japan Adhesive Association Journal Vol. 120, No. 7.300~
Polymerizable compounds introduced as photocurable monomers and oligomers on page 308 can also be used.

The amount of component (1) used is 5 to 50%, preferably 10 to 40%, based on the total composition. Also, component (1) can be replaced with component (
2), it is preferable that the weight ratio is in the range of 0.5/9.5 to 515, and the more preferable range is 1/9.
~3/7.

As the photopolymerization initiator which is component (3) of the present invention, US Pat.
α-carbonyl compounds described in US Pat. No. 70, Asiloin ethers described in US Pat. No. 2.448.828, U.S. Pat. No. 2.722.5
Aromatic acyloin compounds substituted with α-hydrocarbons described in US Pat. No. 3.046,1
27, polynuclear quinone compounds described in each specification of U.S. Patent No. 2.951.758, U.S. Patent No. 3.549.
The triarylimidazole dimer/p-aminophenyl ketone combination described in US Pat. No. 367, the trihalomethyl-8-triazine compound described in US Pat. Acridine and phenazine compounds described in U.S. Pat. No. 3,751,259, U.S. Pat. No. 4,212,9
Contains the oxadiazole compound described in Specification No. 70, and the amount used is about 0.5 to 1
5%, more preferably 2-10%.

As the diazo resin which is component (4) of the present invention, those having a negative effect, being substantially water-insoluble and soluble in organic solvents are suitable. Such diazo resins include 4-diazo-diphenylamine, ■-diazo-4-N, N-dimethylaminobenzene, 1-diazo-4-N, N-diethylaminobenzene, 1-diazo-4-N=ethyl-N -hydroxyethylaminobenzene, 1-diazo-4-N-
Methyl-N-hydroxyethylaminobenzene, 1-diazo-2,5-jethoxy-4-benzoylaminobenzene, 1-diazo-4-N-benzylaminobenzene,
1-Diazo-4-N,N-dimethylaminobenzene, 1
-Diazo-4-morpholinobenzene, 1-diazo-2
,5-dimethoxy=4-P-)lylmercabutobenzene, 1-diaso'-2-ethoxy-4-N,N-dimethylaminobenzene, P-diazo-dimethylaniline, 1-
Diazo-2,5-dibutoxy-4-morpholinobenzene, 1-diazo-2,5-jethoxy-4-morpholinobenzene, 1-diazo-2,5-dimethoxy-4-morpholinobenzene, ■-diazo2 .5-Jetoxy 4-morpholinobenzene, 1-diazo-2,5-jetoxy-4-P-tolylmercaptobenzene, 1-
Diaso'-3=ethoxy 4-N-methyl-N-benzylaminobenzene, 1-diazo-3-chloro-4-N,
N = Nidiethylaminobenzene 1-diazo-3-methyl-4-pyrrolidinobenzene, 1-diazo-2-chloro-
4-N,N-dimethylamino-5-methoxybenzene,
■-diazo 3-methoxy 4-pyrrolidinobenzene,
Diazo monomers such as 3-methoxy-4-diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 3-(n-propoxy)-4-diazodiphenylamine, 3-(isopropoxy)-4-diazodiphenylamine, and formaldehyde. , acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, or benzaldehyde in a molar ratio of 1:1 to 1:0.5, preferably t:O, a
It is a reaction product of a condensate obtained by condensing ~1:0.6 in a conventional manner and an anion. Anions include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitroortho-toluenesulfonic acid,
5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2.4.6-)dimethylbenzenesulfonic acid,
2-Nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphtho-5-sulfonic acid, 2-methoxy-4-hydroxy- Examples include 5-benzoyl-benzenesulfonic acid and para-toluenesulfonic acid. Among these, phosphorus hexafluoride and alkyl aromatic sulfonic acids such as triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid are particularly suitable. The amount of these diazo resins added to the total composition is 1 to 30%, more preferably 3 to 15%.

In addition to the above, it is preferable to add a thermal polymerization inhibitor, such as hydroquinone, p-methoxyphenol,
Di-t-butyl-p-cresol, pyrogallol, t-
Butylcatechol, benzoquinone, 4.4'-thiobis(3-methyl-6-t-butylphenol), 2.2-
Methylene bis(4-methyl-6-t-butylphenol), 2-mercaptobenzimidazole, etc. are useful, and in some cases, dyes or pigments, and a PH indicator etc. as a printing agent may be added for the purpose of coloring the photosensitive layer. You can also do it.

Furthermore, phosphoric acid, phosphorous acid,
Tartaric acid, citric acid, malic acid, dipicolinic acid, polynuclear aromatic sulfonic acid and its salts, sulfosalicylic acid, etc. can be added as necessary. It is also useful to add waxes such as higher fatty acids.

The photosensitive composition of the present invention can be prepared using a suitable solvent such as 2-methoxyethanol, 2-methoxyethyl acetate, propylene glycol monomethyl ether, 3-methoxypropanofur, 3-methoxypropyl acetate, methyl ethyl ketone, or ethylene dichloride. They can be provided on a support alone or in an appropriate combination of solvents dissolved in a mixed solvent. The amount of coverage after drying is about 0.1 g/! A range of from I+'' to about 10 g/m2 is suitable, more preferably from 0.5 to 5 g/m2.

As the support, a dimensionally stable plate-like material is used. Such dimensionally stable plate-like materials include those conventionally used as supports for printing plates, and these can be suitably used. Such supports include:
Paper, paper laminated with plastics (e.g. polyethylene, polypropylene, polystyrene, etc.), e.g. aluminum (including aluminum alloys), zinc,
metal plates such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. films, paper or plastic films laminated or vapor-deposited with metals such as those mentioned above. Of these supports,
Aluminum plates are particularly preferred because they are extremely dimensionally stable and inexpensive. In addition, the special public official
Also preferred are composite sheets in which an aluminum sheet is bonded onto a polyethylene terephthalate film, such as that described in Publication No. 27.

In addition, in the case of a finger holder having a surface made of metal, especially aluminum, surface treatments such as graining, immersion in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, etc., or anodizing are carried out. It is preferable that In addition, as described in U.S. Pat.
As described in Japanese Patent No. 7-5125, an aluminum plate which is anodized and then immersed in an aqueous solution of an alkali metal silicate is also preferably used. The above-mentioned anodizing treatment may be carried out by electrolysis using an aqueous or non-aqueous solution of an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid, or boric acid, or an organic acid such as oxalic acid or sulfamic acid, or a salt thereof alone or in combination of two or more. This is carried out by passing an electric current through a liquid using an aluminum plate as an anode.

Also effective is silicate electrodeposition as described in U.S. Pat. No. 3,658,662.

Furthermore, Japanese Patent Publication No. 46-27481, Japanese Patent Publication No. 52-5
Also useful is a surface treatment that combines a support subjected to electrolytic duplexing and the above-mentioned anodic oxidation treatment and sodium silicate treatment as disclosed in JP-A-8602 and JP-A-52-30503.・Furthermore, JP-A-56-28893
Also suitable are those which are sequentially subjected to brush grain, electrolytic duplex treatment, anodization treatment, and sodium silicate treatment as disclosed in the above publication.

Furthermore, after these treatments, it is also suitable to undercoat with a water-soluble resin such as polyvinyl 7-osphonic acid, polymers and copolymers having sulfonic acid groups in their side chains, polyacrylic acid, and the like.

These hydrophilic treatments are performed not only to make the surface of the support hydrophilic, but also to prevent harmful reactions of the photosensitive composition provided thereon, and to improve the adhesion of the photosensitive layer. This is done for the purpose of improvement etc.

On the layer of the photosensitive composition provided on the support, a material with excellent oxygen barrier properties such as polyvinyl alcohol, acidic cellulose, etc. is used to completely prevent the polymerization inhibition effect caused by oxygen in the air. A protective layer made of a polymer may also be provided. A method of applying such a protective layer is described in, for example, U.S. Pat.
It is described in detail in the specification of No. 729.

A photosensitive plate having the photosensitive composition of the present invention provided on a support is imagewise exposed using a light source rich in ultraviolet rays such as a metal halide lamp or a high pressure mercury lamp, and then treated with a developer to leave the photosensitive layer unexposed. A lithographic printing plate is prepared by removing the portion and finally applying a gum liquid. Preferably, the developer is an aqueous alkaline solution containing a small amount of an organic solvent such as benzyl alcohol, 2-phenoxyethanol, or 2-butoxyethanol, such as U.S. Pat.
Examples include those described in No. 5.171 and No. 3,615,480. Furthermore, Japanese Patent Application Publication No. 1973-
No. 26601, Special Publication No. 56-3946'4, No. 56-
The developers described in each publication of No. 42860 are also excellent as developers for the photosensitive printing plate of the present invention.

〔Effect of the invention〕

By using the photosensitive composition of the present invention, a photosensitive plate that is hardly affected by oxygen can be obtained, so that it can be used practically without an oxygen barrier layer. Therefore, the photosensitive composition of the present invention can be widely used for various printing plates and image formation, and among these, it can be particularly suitably used for photosensitive lithographic printing plates.

Hereinafter, it will be explained in more detail based on examples.

Example 1 A substrate was obtained by the method disclosed in JP-A-56-28893. That is, the surface of an aluminum plate having a thickness of 0.30 mm was grained using a nylon brush and a 400 mesh water suspension of pumice stone, and then thoroughly washed with water.

After etching by immersing it in 10% sodium hydroxide at 70° C. for 60 seconds, it was washed with running water, neutralized with 20% HNO3, and washed with water. This was subjected to electrolytic surface roughening treatment in a 1% nitric acid aqueous solution using a sinusoidal alternating waveform current under the condition of VA = 12.7 V and an anode specific electricity amount of 160 chrome/dm2. When the surface roughness was measured, it was found to be 0.6μ (Ra
display). Subsequently, after immersing in 30% H2SO, aqueous solution and desmutting at 55°C for 2 minutes,
%H2SO, aqueous solution at a current density of 2Δ/dm2 for 2 minutes to a thickness of 2.7 g/m2. Thereafter, it was immersed in a 2.5% sodium silicate aqueous solution at 70° C. for 1 minute, washed with water, and dried.

Next, the following photosensitive solution (2) was prepared.

Photosensitive liquid ■ o Trimethylolpropane doryacrylate 20g0 Photopolymerization initiator having the following structure 2g0Cβ30 Methyl alcohol 150g0 Methyl ethyl ketone 300g After filtering the photosensitive liquid I, apply it onto the substrate using a rotary coating machine to give the weight after drying. It was coated at a concentration of 0 g/m2. Drying is 100
Sample 8 was obtained by drying at ℃ for 2 minutes.

As a comparative example, the poly (allyl methacrylate/2-hydroxyethyl methacrylate/methacrylic acid) copolymer corresponding to component (2) was removed from the photosensitive solution (2) and the entire amount was replaced with the poly(allyl methacrylate/methacrylic acid) copolymer. A photosensitive solution (1) having the composition was prepared, coated and dried in the same manner, and designated as sample B.

In order to compare the degree of oxygen influence of these samples, a Fuji PS step guide (gray scale in which the transmission density changes discontinuously at ΔD=O115) manufactured by Fuji Photo Film ■ was placed on top of the sample. Exposure was performed using a printer manufactured by FT26V2UPNS (light source: 2Kw metal halide lamp). At this time, the printing frame of the printer was exposed to light by adjusting the degree of vacuum, and immediately after being immersed in the following developer for 50 seconds, the surface was lightly rubbed with absorbent cotton to remove the unexposed areas.

Developer Sodium sulfite 5g Benzyl alcohol 30g Jetanolamine 5g Pure water
When we investigated the number of step guides on the plate after 1000 g development, we found that the number of gray scale steps at vacuum degree OTc+rr and vacuum degree 600 Torr was greatly affected by oxygen in Sample B, as shown in Table 1, but in the present invention In sample A, the influence of oxygen was small.

The printer's vacuum level OTorr and vacuum level 600To
Sample A exposed at rr is the printer's vacuum level 600.
When printed on a Heidel printing machine alongside sample B exposed with Torr, more than 100,000 sheets could be printed on both.

Example 2 A photosensitive plate (sample C
) was obtained.

Photosensitive liquid ■ 0 Photopolymerization initiator with the following structure 2g0 Oil Blue #603 1. OgoF-
1771.0 g o Methyl alcohol 150 g Methyl ethyl ketone 300 g This sample C was exposed to light in the same manner as in Example 1 while changing the degree of vacuum, and then developed in the same manner. The number of grayscale solid stages of sample C is 2.5 at vacuum level O, and 600 To vacuum level.
In rr, it was 3.0 steps, and the difference was small.

Example 3 A photosensitive plate (sample D) was obtained in the same manner as in Example 1, except that the following photosensitive liquid (I) was used in place of photosensitive liquid I in Example 1.

Photosensitive liquid (1) 1-acrylic-r', 5-/methacrylic acid) copolymer with a molar ratio of 60/25/15 50go Oil Blue #603 1. OgoF-1
77,1,Og O Ethylene glycol monomethyl ether 500 g O Methyl alcohol 150 g O Methyl ethyl ketone 300 g The sensitivity of sample D was 2.5 steps in gray scale sensitivity at both vacuum degrees of 0 and 600 Torr, and no difference was observed. Furthermore, when this sample was printed using a Heidel printing machine, more than 100,000 prints were obtained, demonstrating high printing durability.

Claims (1)

[Scope of Claims] 1 (1) an ethylenically unsaturated polymerizable compound, (2) an alkaline water-soluble or swellable polymer capable of forming a film, (3) a photopolymerization initiator, and (4) a diazo resin. In the photosensitive composition containing the alkaline water-soluble or swellable and film-formable polymer, (A) a structural unit having an allyl group in its side chain; and (B) a structure having a nitrile group and/or a hydroxyl group in its side chain. A photosensitive composition characterized by being an acidic vinyl copolymer containing units. 2. The photosensitive composition according to claim 1, wherein component (2) is an acidic vinyl copolymer containing 20 to 80 mol% of the structural unit (A) and 70 to 10 mol% of the structural unit (B). thing.