JPS624698B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive material composed of a combination of specific components, and an image forming method using the same. The photosensitive material according to the present invention is a negative type, and can be used as a mask or resist material for metal corrosion plating or soldering process in the production of printed circuit boards, and as a resist material for chemical milling of other metals. It is suitably used as a photosensitive material in the production of printing plates such as multimetal planographic plates and gravure plates. Further, the image forming method according to the present invention is suitably applied to the production of the above-mentioned printed circuit boards and printing plates. Conventionally, various negative photosensitive materials have been known, and these conventional techniques are classified into the following types. Unsaturated groups in the polymer compound itself,
A method in which functional groups such as azide groups are chemically bonded, and if necessary a photoactive agent is present in the coexistence to cause direct photocrosslinking between functional polymer compounds. It consists of a crosslinking agent, which is a low molecular weight compound that is nonvolatile at room temperature and usually has two or more unsaturated groups or functional groups such as azide groups, and a photoactive agent. A method in which a functional polymer compound is photo-crosslinked, and a method that combines the above methods and uses a functional polymer compound and a crosslinking agent in combination. In the above methods, a reaction is carried out to introduce a functional group into a polymer compound, or a monomer having two different functional groups is polymerized with one functional group, and the other functional group is polymerized. Since it involves one of the reactions that causes the polymer to retain the produced polymer, special consideration must be given to quality reproducibility in manufacturing. Furthermore, since the functional groups are built into the polymer itself, it tends to gel due to dark reactions during storage, and when used, development residues in the form of scum or whiskers are likely to be produced, resulting in image breakage. may cause problems. In contrast, in this method, since the polymer compound is non-functional, there are fewer restrictions on handling such as purification, and the range of selection of the polymer compound is wide. The crosslinking agent can be selected independently by considering only its compatibility with the polymer compound.
It has the general characteristics that it is easy to obtain compositions with excellent image sharpness and storage stability. Typical examples include methacrylic acid-methyl methacrylate (molar ratio 1:9) copolymer, a compound having an ethylenically unsaturated group (crosslinking agent), and anthraquinone (sensitizer), or bisimidazole derivatives and diaminobenzoyl. This method uses a mixture with derivatives (sensitizers) (Special Publication No. 1973-
35687, 48-38403). In addition, there are also products consisting of cellulose acetate butyrate or cellulose acetate, a compound with an ethylenically unsaturated group (crosslinking agent), and a photoactive agent (Special Publication No. 49).
−11936). However, in the method described above, a protective layer or protective film with low oxygen permeability that is non-photosensitive and transparent to actinic light is placed on a coating layer of a photosensitive material formed on the surface of a planar substrate. It is necessary to provide Without this kind of protective layer, practically sufficient sensitivity and resolution cannot be obtained. This is presumed to be related to the fact that photocrosslinking by a radical mechanism of ethylenically unsaturated groups is significantly inhibited by oxygen in the air. In this respect, in the method of directly introducing functional groups into a polymer compound, the influence of oxygen in the air can be practically ignored. To provide this type of protective layer, a method is used in which, for example, an aqueous solution of a water-soluble polymer compound such as polyvinyl alcohol or polyvinylpyrrolidone is cast onto the photosensitive layer to form the protective layer. Further, in order to provide a protective film, a method of covering with an insoluble thermoplastic film such as a thin polyethylene terephthalate film or a polypropylene film having a thickness of about 25 μm is used. In the case of a protective layer using the water-soluble polymer compound described above, the protective layer is also removed at the same time during weak alkaline development, and in the case of a protective film, development is performed after peeling off the insoluble thermoplastic protective film. On the other hand, as a compound having an ethylenically unsaturated group (crosslinking agent), a compound that is viscous and liquid at room temperature is usually used, but in order to obtain the desired sensitivity,
In the conventional method, it is necessary to add a cross-linking agent to the extent that the photosensitive layer becomes quite sticky, and in this case, when the original pattern is closely printed on the photosensitive layer, the stickiness becomes an obstacle and damages the original without a protective layer. . For this reason as well, the presence of a protective layer is essential in the conventional method. When providing a protective layer, usually a solution of a photosensitive material in a low-boiling organic solvent is cast on the substrate surface, a photosensitive layer is formed by heating and drying, and a water-soluble polymer compound solution is cast on the photosensitive layer. Then, the protective layer is created by heating and drying again to remove water, but this process is complicated. In addition, when a protective film is provided, a process of laminating the film on the photosensitive layer is required, and in addition, in systems where a protective film is provided, it is actually difficult to resolve patterns with a line width smaller than the thickness of the film. Furthermore, scattering of active light at the interface between the photosensitive layer and the protective layer also leads to a reduction in image sharpness. As described above, the above-mentioned methods have hitherto been accompanied by disadvantages and restrictions in use since the presence of a protective layer is essential. The present invention improves upon the drawbacks of the prior art, and is a photosensitive material belonging to the above-mentioned series, as well as an imaging method using the same. The first invention is the following photosensitive material. Copolymer (a) consisting of styrene and monoalkyl maleate, 5 to 35 mol% methacrylic acid (or acrylic acid) and 95 to 65 mol% methacrylic acid alkyl ester (or alkyl acrylate) ester) [copolymer (b)], a compound having an ethylenically unsaturated group containing or not containing a nitrogen atom [crosslinking agent],
and a photosensitive material composed of a photoactive agent. The second invention is the following image forming method. A photosensitive coating layer having a thickness of 1 to 200 μm is formed on the surface of a substrate using the photosensitive material of the first invention, without providing a protective layer or a protective film on the photosensitive coating layer. The photosensitive coating layer is exposed to active light through an original image formed on a film that transmits active light, and then a photocrosslinked image is formed on the substrate surface by weak alkaline solution development. Image formation method. Each invention will be explained in detail below. The photosensitive material according to the first invention is composed of the following components. Copolymer (a) exhibits the function of a binder (binding agent) for a crosslinking agent having a functional group, and at the same time is a high polymer that exhibits the function of being crosslinked by the crosslinking agent upon irradiation with light and becoming insolubilized in a developer. It is a molecular compound and is a copolymer of styrene and maleic acid monoalkyl ester. Copolymer (b) is a polymer compound that exhibits the same function as copolymer (a), and contains 5 to 35 mol% methacrylic acid (or acrylic acid) and 95 to 65 mol% methacrylic acid. It is a copolymer made of alkyl ester (or acrylic acid alkyl ester). In the photosensitive material of this invention, copolymer (a) and
The two types of polymer compounds (b) that have substantially no functional groups are simultaneously contained as essential components. Both components contain free carboxyl groups so that the unexposed areas can be removed from the substrate surface by a weakly alkaline developer. Copolymer (a) is a combination of styrene and maleic acid monoalkyl ester. This combination was particularly selected after studying a large number of copolymers that are combinations of compounds of group (a) and group (b) below. (a) Styrene or its derivatives such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, p-methoxystyrene, vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, phenyl vinyl ether, acrylonitrile (or nitriles such as (methacrylic nitrile), alkenes such as cyclohexene and octadecene-1, and ketoalkenes such as methyl vinyl ketone and methyl isopropenyl ketone. (b) Vinyl monomers having a free carboxyl group, such as monoalkyl maleate, monoalkyl fumarate, itaconic acid, and vinyl acetic acid. In this invention, the copolymer of styrene and monoalkyl maleate (preferably lower alkyl having 4 or less carbon atoms) has a molar ratio of styrene to monoalkyl maleate of 5 to 5.
A composition of 1::1 is preferred. Although the copolymer (a) can be easily synthesized by a known method and is also available as a commercial product, an example of the synthesis method will be given for reference. Reference Example 1 [Copolymer (a)] Benzene 1, 62.4 g of styrene, and 58.8 g of maleic anhydride were added to a reactor equipped with a reflux condenser, nitrogen inlet, and stirrer, and the mixture was kept at room temperature under a nitrogen atmosphere. Make a homogeneous solution and add 0.6g of benzoyl peroxide to this.
was added and reacted under reflux for 1 hour, resulting in the precipitation of a copolymer. After cooling this to room temperature, it was filtered and dried to produce poly(styrene-co-maleic anhydride) with a concentration of 91.5%.
I got g. Next, 30 g of the above copolymer was dispersed in 270 g of isopropyl alcohol, and 0.1 ml of 35% hydrochloric acid was added.
After stirring at 82-83℃ for 28 hours,
1 ml of 4% sodium hydroxide methyl alcohol solution
was added and filtered. Isopropyl alcohol was distilled off and the filtrate was concentrated until the volume of the filtrate became about 2/3 to 1/2.
The obtained concentrate was poured into a solvent (ISOPAR - alkane solvent manufactured by Etsuso, USA) under stirring, and 39 g of poly(styrene co-maleic acid monoisopropylate) was added.
I got it. Yield 97.5%, [η] = 0.140 (25°C, ethylene glycol monomethyl ether), acid value 172
[Styrene: Monoisopropyl maleate≒1:
1 (molar ratio)]. Copolymer (b) is a copolymer consisting of 5 to 35 mol% of methacrylic acid (or acrylic acid) and 95 to 35 mol% of methacrylic acid alkyl ester (or acrylic acid alkyl ester). The combination of methacrylic acid and methacrylic acid alkyl ester is particularly desirable, and it is advantageous to use a copolymer in which the degree of polymerization is kept low by adding a polymerization inhibitor such as mercaptan, as shown in the reference example below. .
Incidentally, regarding the copolymer (b), a number of copolymers with monomers having free carboxyl groups were investigated, and the above-mentioned combination was selected because it had good coating film formation properties for photosensitive materials. Copolymer (b) can also be easily synthesized by known methods and is also available as a commercial product;
An example of the synthesis method is given for reference. Reference Example 2 540 g of commercially available kerosene treated with anhydrous calcium chloride was added to a reactor equipped with a stirrer equipped with a nitrogen inlet, purged with nitrogen at 70°C, and 72 g of methyl methacrylate, 15.5 g of methacrylic acid, azobis A mixed solution consisting of 0.7 g of isobutyronitrile and 1.8 ml of n-dodecyl mercaptan was dropped into kerosene at 75°C for 1 hour, and stirred and reacted at 75°C for 5 hours to precipitate the resulting copolymer. After filtering, it was dried at 85°C under reduced pressure to obtain 83 g of poly(methacrylic acid-co-methyl methacrylate).
Yield 95%, [η] = 0.169 (25°C, ethylene glycol monomethyl ether), acid value 115 [methacrylic acid: methyl methacrylate ≒ 8:2 (mol ratio %)]. In this invention, the combination of copolymers (a) and (b) is essential, and the object of this invention cannot be achieved without either one. Even if a photosensitive material is prepared using copolymer (a) alone [copolymer (b) is not used] and a crosslinking agent and a photoactivator are added, a photosensitive layer with a thickness of 5 to 30 μm is formed on a copper or aluminum substrate. However, in both cases, cracks occurred in the layers, and the products were completely impractical. Next, when a similar photosensitive material was prepared using copolymer (b) alone (without copolymer (a)) and a photosensitive layer was formed, the film formation properties were satisfactory. However, the film did not exhibit sufficient sensitivity for practical use, and the film showed considerable stickiness due to the crosslinking agent, making it inconvenient for use. However, in the system in which copolymers (a) and (b) coexisted, the photosensitive layer did not exhibit stickiness to the touch even at 70 to 80°C, and the photosensitive speed was also satisfactory. The surprising fact here is that the thickness of the photosensitive material made from the photosensitive material containing copolymers (a) and (b)
In the case of the 200 μm photosensitive layer (photosensitive coating layer), the protective layer or protective film that was considered necessary in the above-mentioned method of the prior art is unnecessary. In this way, the photosensitive material according to the present invention is
Regardless of whether it belongs to the above-mentioned series of prior art systems, it does not require a protective layer, etc., which has been considered necessary up to now. The weight ratio of copolymers (a) and (b) is (a):(b)=10:
It is desirable that the ratio is within the range of 1 to 1:3 and that the relationship (a)>(b) is satisfied. The crosslinking agent in this invention is a compound having an ethylenically unsaturated group containing or not containing a nitrogen atom. Preferably the boiling point at room temperature is 150
It is a compound having two or more ethylenically unsaturated groups whose temperature is ℃ or higher. A low-viscosity compound having one ethylenically unsaturated group and having a boiling point of 150° C. or higher at room temperature has a low viscosity, and thus also exhibits the function of adjusting the viscosity of a photosensitive material solution. Specific examples of crosslinking agents include furfuryl acrylate, diethylene glycol diacrylate,
Tetraethylene glycol diacrylate, hexamethylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, resorcinol diacrylate, p/p'-dihydroxydiphenyl diacrylate , bisphenol A diglycidyl diacrylate, or the same structure in which a methacrylic group is introduced in place of the acrylic group, as well as diallylphthalate, diallylacrylamide, methylenebisacrylamide, and the like. Examples of low-viscosity compounds having one ethylenically unsaturated group include 2-ethylenehexyl acrylate, diethylene glycol monoacrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate.
-Hydroxypropyl acrylate, 2-hydroxyhexyl acrylate, or the same structure in which a methacrylic group is introduced in place of the above acrylic group,
Furthermore, there are N-vinylpyrrolidone and the like. The crosslinking agent is selected from among the above-mentioned examples in consideration of photosensitive speed, compatibility with the copolymer mixture, corrosion resistance of the photocrosslinked film, and the like. The amount of crosslinking agent in the photosensitive material is usually between 5 and 150% of the copolymer mixture.
% by weight. The photoactivator (photosensitizer) used in this invention may be a known one, and specific examples include benzophenone, benzyl, p.p'-bis(dimethylamino) belonging to ketones, various derivatives thereof, or quinoid compounds. ) benzophenone, p・p′-bis(diethylamino)benzophenone, benzoin ethyl ether, benzoin isopropyl ether, anthraquinone, acenaphthenequinone, β-
tert-butylanthraquinone, phenanthrequinone, etc.; furthermore, compounds belonging to heterocyclic compounds such as primulin, carbazole, N-methyl-3-nitrocarbazole, xanthone, thioxanthone, etc.; and compounds belonging to polyhaloalkane and its derivatives such as tetra Carbon bromide, ω・ω・ω-tribromomethylphenyl sulfone, triphenylamine, etc. The amount of photoactive agent in the photosensitive material usually ranges from 0.01 to 20% by weight, preferably from 0.1 to 10% by weight, based on the total amount of copolymer mixture and crosslinker. Other components can be added to the photosensitive material of this invention if desired. Such ingredients include thermal polymerization inhibitors such as hydroquinone, p-methoxyphenol, pyrogallol, 2,6-di-tert-butyl-p-cresol, Kyuferon, etc. to suppress premature crosslinking during storage. .
The amount of thermal polymerization inhibitor usually ranges from 0.001 to 1% by weight based on the total amount of copolymer mixture and crosslinking agent. Furthermore, in order to facilitate identification of the coated film of the photosensitive material and the photocrosslinked image, a coloring agent such as an oil-soluble dye or finely divided pigment particles can be added. In addition, a surfactant may be added to improve the leveling properties of the coating film and the wettability to the substrate surface. Specific examples of colorants and surfactants are given in the Examples. The image forming method according to the second invention and the characteristics of the photosensitive material associated therewith will be described. Although photosensitive materials can be thermally melted and made into injection sheet or film forms, they are usually dissolved in an organic solvent, cast onto a substrate, that is, the surface of the workpiece, and the solvent is evaporated to form a photosensitive layer. let Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, cyclic ethers such as tetrahydrofuran and dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether,
Glycol mono- or diethers such as diethylene glycol diethyl ether, and glycol esters such as methyl glycol acetate may be used alone, or dichloroethyl ether may be used alone.
It is used by mixing it with haloalkanes such as tan, or aromatic compounds such as chlorobenzene and toluene. The concentration of the photosensitive material solution depends on the coating method on the substrate, such as dip coating, curtain coating, roll coating, kiss coating, wire bar coating,
It is determined by the spinner (or whaler) coat, etc., and further determined by the desired thickness of the photosensitive layer. The photosensitive coating layer (photosensitive layer) with a thickness of 1 to 200 μm formed on the surface of the substrate does not require the provision of a non-photosensitive protective layer or protective film as in the prior art. If it is less than 1 μm, the photosensitive speed becomes considerably slow when proximity exposure is performed, and the characteristics of the photosensitive material cannot be utilized.
Further, if the thickness exceeds 200μ, a commensurate increase in effect cannot be expected, and furthermore, it is not economical. Therefore, the photosensitive material of the present invention should be used by contact exposure when the thickness of the photosensitive layer is in the range of 1 to 200 microns. When the photosensitive layer is exposed to light through an original image formed on a film that transmits active light, photocrosslinking occurs in the exposed areas. As a light source for this active light, low-pressure, high-pressure, or ultra-high-pressure mercury lamps, metal halide mercury lamps, carbon arc lamps, etc., which generate strongly in the ultraviolet and near ultraviolet regions, are advantageously used. Next, by immersing the exposed photosensitive layer on the substrate in an aqueous solution of an inorganic base such as sodium carbonate or sodium silicate, or an organic base such as ammonia or ethanolamine at a concentration of several percent, the unexposed areas can be easily removed. removed, yielding a negative image of the original. Depending on the purpose of use, the substrate surface on which the photocrosslinking agent remains is
After being subjected to processes such as corrosion and plating, the photocrosslinked portion can be easily peeled off by immersing it in a caustic alkali aqueous solution with a concentration of about 5%. The present invention will be explained below with reference to Examples. Example 1 [Copolymer (a)] 30 parts by weight of poly(styrene-co-monoisopropyl maleate) of Reference Example 1 [Copolymer (b)] Poly(methacrylic acid-co-methacrylic acid) of Reference Example 2 methyl) 40 parts by weight [Crosslinking agent] Tetraethylene glycol diacrylate
41 parts by weight [Photoactivator] Benzoin ethyl ether 6 parts by weight [Thermal polymerization inhibitor] p-methoxyphenol 0.01 parts by weight [Colorant] CI Solvent Red No. 109 0.5 parts by weight [Surfactant] Polyoxyethylene sorbitan monolaurate
0.5 parts by weight of the above as ethylene glycol monomethyl ether
It was dissolved in 265 parts by weight to obtain a photosensitive solution of 30 cps (25°C). This photosensitive solution was applied using a roll coater to a 1-ounce copper foil single-sided phenolic resin laminate and dried by heating at 80°C to form a 10 μm thick photosensitive layer on the copper surface. The copper surface was degreased with 1,1,1-trichloroethane, treated with 5% HCl, and washed with water. A polyethylene terephthalate film-based test pattern was vacuum-nitrified on the photosensitive layer, and irradiated with a high-pressure mercury lamp (3 kW) at a distance of 1 m for 60 seconds (intensity 4.7 mW/m ² ). The exposed laminate was immersed in a 0.5% Na ₂ CO ₃ aqueous solution at 25° C. for 2 minutes, then washed with water, rinsed with 3% H ₃ PO ₄ , washed again with water, and dried. Next, the laminate was etched by immersing it in a 40°Be FeCl ₃ aqueous solution for 5 minutes at 25°C, then washed with water, and etched with 5%
The photocrosslinked portion was peeled off by immersing it in a NaOH aqueous solution at 25°C for 2 minutes. The copper pattern obtained by the above treatment had very good edge cutting, no permeation of the copper etching solution was observed, and a line width of 20 μm was resolved. Example 2 [Copolymer (a)] Poly(styrene-co-monoethyl maleate)
[Mole ratio 1.5:1.1] 35 parts by weight [Copolymer (b)] Poly(methacrylic acid-co-methyl methacrylate)
[Mole ratio 8.3:1.7] 28 parts by weight [Crosslinking agent] Trimethylolpropane triacrylate
18 parts by weight diethylene glycol diacrylate 17 parts by weight [Photoactivator] p・p′-bis(diethylamino)benzophenone
0.35 parts by weight Benzyl 0.24 parts by weight [Thermal polymerization inhibitor] Kyuferon 0.01 parts by weight [Coloring agent] 1-methylaminoanthraquinone (red disperse dye) 0.7 parts by weight [Surfactant] Polyoxyethylene sorbitan monolaurate
0.4 parts by weight of the above as ethylene glycol monomethyl ether
It was dissolved in 203 parts by weight to obtain a photosensitive solution of 38 cps (25°C). On the surface of a commercially available trital plate made of iron-copper-chromium (top layer) with an iron substrate, a top-filling photosensitive liquid was applied by rotating a hoarer at 60 rpm.
It was dried at ℃ to form a photosensitive layer with a dry film thickness of about 15μ. Using a printing test pattern, it was exposed under the same conditions as in Example 1, then immersed in a 1% ethanolamine aqueous solution at 25°C for 2 minutes, developed, washed with water, and dried, containing 30% by weight of CaCl ₂ and 25% by weight of ZnCl ₂ , in an aqueous chromium corrosive solution containing ₂ % by weight of NH ₄ Cl and 3% by weight of concentrated nitric acid.
A tri-metal plate was prepared by immersing the plate at 25°C until the unexposed copper surface was exposed, and it resolved 175 lines/inch and had good halftone dot reproducibility of 5 to 95%.
In this case, the film was removed under the same conditions as in Example 1. Example 3 [Copolymer (a)] Poly(styrene-co-maleic acid monomethylate) 35 parts by weight [Styrene:maleic anhydride = 2:1 (mole ratio) SMA#2000 manufactured by Alco Chemical Co., Ltd. in the United States with methyl alcohol [Copolymer (b)] Poly(methacrylic acid-co-methyl methacrylate)
[Mole ratio: 7.2:2.8] 30 parts by weight [Crosslinking agent] Trimethylolpropane triacrylate
22 parts by weight Trimethylolpropane diacrylate 19 parts by weight [Photoactivator] p・p′-bis(dimethylamino)benzophenone
0.4 parts by weight Acenaphthenequinone 0.05 parts by weight [Thermal polymerization inhibitor] p-methoxyphenol 0.02 parts by weight [Coloring agent] 5 parts by weight CI Pigment Blue 3 The above was mixed with ethylene glycol monomethyl ether
Dissolved in a mixed solvent of 200 parts by weight and 100 parts by weight of diethylene glycol diethyl ether.
℃) was obtained. This photosensitive solution was applied with a doctor blade to a dry film thickness of 25 μm on a polyimide-based flexible printed circuit board with 1 oz copper foil, dried, and tested for plating resistance and solder resistance. That is, after treating the copper surface with 3% HCl, a tin-lead borosilicate plating solution (High Slow, manufactured by Akebono Sangyo Co., Ltd.) was used, cathode current density was 1.62 A/dm ² , anode to cathode ratio was 2:1, for 3 minutes. The test was conducted under conditions in which a plating layer with a thickness of 2.5μ was formed. As for solder resistance, immersion in a solder bath kept at 260°C for 10 seconds was repeated three times. As a result of the test, it was determined that the above photosensitive material had sufficient plating resistance and soldering resistance. Furthermore, this photosensitive solution was stored in a cool, dark place in the laboratory for 18 months, but there was no change in photosensitive speed or resolution, and no signs of gelation were observed. Comparative examples are listed below. Comparative Examples 1 to 3 [Crosslinking agent] 50 parts by weight of triethylene glycol diacrylate [Photoactivator] 0.55 parts by weight of benzoin isopropyl ether [Thermal polymerization inhibitor] p-methoxyphenol 0.02 parts by weight [Coloring agent] CI Solvent Blue 73 0.5 Parts by weight [Surfactant] Polyoxyethylene sorbitan monolaurate
0.5 parts by weight The above components were common, and the following copolymers were used in Comparative Examples 1 to 3, respectively.

[Table] For Comparative Examples 1 to 3, each copolymer and common component were dissolved in a mixed solvent of 250 parts by weight of ethylene glycol monoethyl ether and 80 parts by weight of ethylene glycol monoethyl ether acetate, and three types of photosensitive liquids were mixed. Prepared. Apply each photosensitive liquid at 60r.pm using a rotary coating machine.
The photosensitive layer was coated on a phenolic resin laminate with one ounce of copper foil on one side and dried at 80°C to form a photosensitive layer with a thickness of 10 to 15 μm. The surface of the copper foil was degreased with 1.1.1-trichloroethane, treated with 5% HCl, and washed with water. Polyethylene terephthalate film-based test patterns were vacuum-adhered to each of the three types of photosensitive layers, and irradiated with an ultra-high pressure mercury lamp (3 kW) at a distance of 1 m for 60 seconds (intensity 4.7 mW/cm ² ). After exposure, each laminate was placed in 0.5% _Na2CO3 aqueous solution at 25℃ _.
The sample was immersed in water for 2 minutes, washed with water, rinsed with 3% H ₃ PO ₄ and washed again with water in this order, and then heated and dried. Comparative tests were conducted on the above three types of photosensitive liquids and photosensitive layers, and the results shown in the table below were obtained.

【table】

[Table] indicates excellent, good, and
and not available.
The evaluation method for the test items is as follows. Coating property: Coating film formation is evaluated based on the uniformity of the surface of the photosensitive layer. Photosensitivity speed: /2 After exposure and development of a step tablet (manufactured by Kodak), evaluation is based on the time required to print until a 6-step solid image is obtained. Resolution: Evaluated by the resolution of a straight line image with a line width of 100μ and edge breakage. Adhesiveness: Judgment is made by the finger touch test for stickiness and the presence or absence of adhesion to the original after close exposure to the original with a silver salt image. Developability: Evaluated based on the development time required for development with a 0.5% Na ₂ CO ₃ aqueous solution and the presence or absence of development line residue. Peelability: Judged by the difficulty of peeling with a 5% NaOH aqueous solution. Corrosion resistance: Judging from the presence or absence of a cut in the corrosion image created by a 40°Be FeCl ₃ aqueous solution for copper foil corrosion and the presence or absence of corrosive solution.

Claims (1)

[Claims] 1. Copolymer consisting of styrene and maleic acid monoalkyl ester [copolymer (a)], 5 to 35 mol%
methacrylic acid (or acrylic acid) and 95 to 65 mol% of methacrylic acid alkyl ester (or acrylic acid alkyl ester) [copolymer (b)], ethylenic with or without nitrogen atoms A photosensitive material composed of a compound having an unsaturated group [crosslinking agent] and a photoactive agent. 2 Copolymer consisting of styrene and maleic acid monoalkyl ester [copolymer (a)], 5 to 35 mol%
methacrylic acid (or acrylic acid) and 95 to 65 mol% of methacrylic acid alkyl ester (or acrylic acid alkyl ester) [copolymer (b)], ethylenic with or without nitrogen atoms A photosensitive material composed of a compound having an unsaturated group [crosslinking agent] and a photoactive agent is used to form a photosensitive coating layer with a thickness of 1 to 200 μm on the surface of the substrate, and at this time, the photosensitive material is The photosensitive coating layer is formed without a protective layer or protective film, and the photosensitive coating layer is exposed to active light through an original image formed on a film that transmits active light, and then the substrate is developed by weak alkaline solution development. An image forming method characterized by forming a photocrosslinked image on a surface.