JPH0160133B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive composition used in photolithography, processing of electronic parts, and the like. A so-called chromium salt-polyvinyl alcohol-based photosensitive composition, which is a mixture of polyvinyl alcohol and dichromate as a photosensitizer, is known as a photosensitive composition used in photolithography, processing of electronic parts, and the like. This composition is widely used because it is inexpensive, the resulting photosensitive film has good properties, and it is easy and safe to handle because water can be used as a solvent for cleaning and removing unexposed areas, i.e., for development. There is. However, since this composition contains hexavalent chromium, which is a harmful substance, a water-developable photosensitive composition that does not contain this harmful substance is desired. From this point of view, photosensitive compositions have been discovered in which non-toxic organic photosensitizers such as diazonium salts and water-soluble azides are added to ordinary polyvinyl alcohol. Organic photosensitizer-polyvinyl alcohol based photosensitive compositions are usually prepared by coating and drying an aqueous solution of a photosensitizer and polyvinyl alcohol on a substrate for photolithography, electronic parts, a glass panel of a cathode ray tube, or the like. The formed photosensitive film is then irradiated with light to make the exposed areas insoluble in water, and then developed with water to dissolve and remove the unexposed areas to obtain the desired image. Therefore, the photosensitive composition is required to have high photosensitivity, good developability, good adhesion of the insolubilized film in the exposed area to the substrate, and not to peel off during development. By the way, polyvinyl alcohol, which has been conventionally used, has low photosensitivity, so it is necessary to use a large amount of organic photosensitizers, which have lower photosensitivity than chromium salts. Organic photosensitizers are expensive, and it is desirable to use only a small amount of them.Additionally, when trying to obtain a desired image through long exposure, work efficiency decreases, and there are other problems such as difficulty in obtaining a clear image. Conventional photosensitive compositions based on polyvinyl alcohol and an organic photosensitive agent are not satisfactory. The present inventors conducted extensive research to overcome the above-mentioned drawbacks of conventional polyvinyl alcohol, and as a result, the following general formula () was found in the molecule. (Here, R ¹ is a hydrogen atom or a lower alkyl group,
Each R ² represents an alkyl group. The present invention was completed based on the finding that a modified polyvinyl alcohol containing a copolymerized unit having a crosslinkable group represented by the following formula satisfies the above-mentioned purpose. That is, by using a photosensitive liquid formed from an aqueous solution containing modified polyvinyl alcohol (polyvinyl alcohol may be abbreviated as PVA) of the present invention and an organic photosensitive agent, it is made insoluble in developing water by light irradiation. The amount of exposure required for this process can be reduced compared to conventional photosensitive solutions using unmodified polyvinyl alcohol. What is even more surprising is that compared to using conventional PVA, the adhesion of the insolubilized photosensitive film to the substrate is better, and there is very little peeling or falling off of the insolubilized part during water development, resulting in clear images. . This effect is thought to be due to the fact that the adhesiveness and adhesiveness of the insolubilized film of the modified polyvinyl alcohol of the present invention to the substrate is superior to that of conventional polyvinyl alcohol, and is thought to be due to the effect of the crosslinkable group. The modified PVA with crosslinkable groups used in the present invention is a vinyl ester, especially vinyl acetate, with the formula CH ₂ = CR ¹ --CONHCH ₂ O--R ² (R ¹ is a hydrogen atom or a lower alkyl group, R ² is an alkyl basis)
Monomers represented by, especially N-alkoxymethyl (meth)acrylamide in which R ¹ is hydrogen or a methyl group and R ² is an alkyl group having 1 to 4 carbon atoms, particularly preferably N-methoxymethyl acrylamide or N-n - copolymerize with butoxymethylacrylamide using a radical polymerization initiator, and then apply an alkaline catalyst to the alcohol solution of this copolymer to partially or highly saponify the vinyl ester units in the copolymer. It is produced by converting it into vinyl alcohol units. The vinyl ester that can be used in the production of the modified PVA used in the present invention becomes vinyl alcohol if it is saponified after copolymerization, so any vinyl ester can have the same effect in terms of bed quality but is less economical. Vinyl acetate is preferred. In addition, the other copolymerization component CH ₂ = CR ¹
Specific examples of the monomer represented by ―CONHCH ₂ O―R ² (R ¹ is a hydrogen atom or a lower alkyl group, R ² is an alkyl group) are N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-methoxymethylmethacrylamide,
-Ethoxymethylacrylamide, N-ethoxymethylmethacrylamide, Nn-propoxymethylacrylamide, Nn-propoxymethylmethacrylamide, N-isopropoxymethylacrylamide, N-isopropoxymethylmethacrylamide, Nn-butoxymethyl Acrylamide, N-n-butoxymethylmethacrylamide, N-isobutoxymethylacrylamide, N
-isobutoxymethyl methacrylamide, N-
tert-butoxymethylacrylamide, N-tert
-butoxymethyl methacrylamide,
Among these, N-methoxymethylacrylamide or Nn-butoxymethylacrylamide is particularly preferred in terms of effectiveness and economy. These monomers have been well known for a long time, for example, as described in the British patent.
No. 955420 discloses copolymers with vinyl acetate and acrylic esters. However, saponified copolymers produced by saponifying copolymers of N-alkoxymethyl (meth)acrylamide and vinyl ester are not known, and industrially Modified PVA with important excellent performance
is not known at all to be obtained. The aforementioned saponified product of the copolymer of N-alkoxymethyl (meth)acrylamides and vinyl ester and its specific production method have been developed by the present inventors and have already been published in Japanese Patent Application No. 56-176024 (Japanese Unexamined Patent Publication No. 176024). 58-76403), 56-178594 (Japanese Patent Application Publication No.
58-80304), but in the production of such modified PVA, the degree of modification increases as the chain length of the alkyl group of the N-alkoxymethyl (meth)acrylamide used increases and/or If the content of vinyl acetate units is high, the resulting aqueous solution of modified PVA may be degraded, so if you are aiming for water-soluble modified PVA, the type and content of N-alkoxymethyl (meth)acrylamide, the vinyl acetate unit It is necessary to adjust the content of It is industrially preferable to use a method in which a white gel or precipitate is produced as the saponification reaction progresses, as in the case of ordinary PVA, and by grinding, washing, and drying this as necessary, modified PVA can be produced. A copolymer powder can be obtained. For the purpose of the present invention, the content of the aforementioned crosslinkable groups is 0.01 to 20 mol%, preferably 0.1 to 10 mol%,
The degree of saponification is preferably in the range of 60 to 100 mol%, and the degree of polymerization is preferably in the range of 100 to 6,000. Furthermore, the content of crosslinkable groups
0.1 to 5 mol %, saponification degree of 70 to 98 mol %, and polymerization degree of 200 to 5,000 are desirable because they have high photosensitivity, good developability, and better adhesion of the photosensitive film to the substrate. In addition to the modified PVA having crosslinkable groups of the present invention, other photosensitive polymer substances such as normal PVA, acrylamide copolymer-modified PVA, carboxyl group-modified PVA, sulfonic group-modified PVA, hydrophobic group-modified PVA, cationic group-containing Modifications such as modified PVA
PVA may be used in combination, and gelatin, glue, etc. may also be used in combination. Further, the organic photosensitizer used in the present invention includes a compound that can make the photosensitive composition insoluble in water by light irradiation when used in combination with the above-mentioned crosslinkable group-modified PVA. For example, tetrazonium salts, diazide compounds, diazo resins, etc. alone or in mixtures, photopolymerization initiators such as alkyl ethers of benzoin, ω-
Monomers that can be photopolymerized with bromoacetophenone, d-bromoisobutylphenone, etc. in the presence of a photopolymerization initiator to form a high polymer, such as 1
Examples thereof include esters of acrylic acid or methacrylic acid of lower alkanols having two or more hydroxyl groups, or mixtures of polyethylene glycol etherified or esterified on one side with esters of acrylic acid or methacrylic acid.
These organic photosensitizers are preferably water-soluble compounds, and are preferably compatible with the crosslinking group-modified PVA aqueous solution. Preferred organic photosensitizers include diphenylamine-4-diazonium chloride/formalin condensation resin, dimethylaniline-4-diazonium chloride/formalin condensation resin, 2,5-dimethoxyphenylmorpholine-4-diazonium zinc chloride double salt/formalin condensation resin, and the like. diazo resin, 3,
3'-dimethoxydiphenyl-4,4'-bisdiazonium chloride zinc chloride double salt, 3,3'-diethyldiphenyl-4,4'-bisdiazonium chloride zinc chloride double salt, diphenyl-4,4'-bis Azonium chloride zinc chloride double salt, N-ethyl-N-benzylaniline-4-diazonium chloride zinc chloride double salt, N-dimethylaniline-4-diazonium chloride, 3,3'-dimethoxydiphenyl-
Tetrazonium salts such as 4,4'-bisdiazonium chloride, 3,3'-dimethoxydiphenyl-4,4'-bisdiazonium sulfate, diazonium salts, 6-azido-2-(4'-azidostyryl)
Diazide compounds such as benzimidazole, 4,4'-diazidostilbene-2,2'-disulfonamide, benzoin, benzoin methyl ether,
Benzoin ethyl ether, α-methylbenzoin, pivaloin, anthraquinone, 1-chloroanthrquinone, 2-methylanthraquinone, ω-
A photopolymerizable monomer that is miscible with PVA and a photopolymerization initiator such as bromoacetophenone, α-bromoisobutylophenone, or 1,4-naphthoquinone, such as ethylene glycol acrylate, ethylene glycol methacrylate, or ethylene glycol di Mixed systems with methacrylate, triethylene glycol methacrylate, polyethylene glycol dimethacrylate, β-oxypropyl methacrylate, etc. can be mentioned. In addition to these organic photosensitizers, known sensitizers such as uranyl acetate compounds can be used in combination as appropriate. Additives such as plasticizers, dispersants, and antifoaming agents, phosphor particles in the case of producing a fluorescent surface for television cathode ray tubes, and pigments in the case of photocurable paints are added as necessary. Examples regarding the photosensitivity of photoinsolubilization by ultraviolet rays and the characteristics of the film of the photosensitive composition of the present invention will be described below, but the present invention is not limited thereto. Note that parts and % mean parts by weight and % by weight unless otherwise specified. Example 1 Diphenylamine-4-diazonium chloride/formalin condensation was added to 100 parts of a 10% aqueous solution of modified PVA containing 2 mol% of N-methoxyacrylamide as a copolymerized unit, a degree of saponification of 89 mol%, and an average degree of polymerization of 2020. A photosensitive solution prepared by adding and mixing 1 part of resin was coated uniformly on a zinc plate using a rotary coater and allowed to dry.The line drawing was placed in close contact with the zinc plate in a vacuum printing frame and exposed for 3 minutes using a 2000 Lux chemical lamp as the light source. Then, wash and develop with water. 5% of the image board you can get
After hardening by immersing in a chromic acid aqueous solution for 30 minutes, an acid-resistant image resist is produced by burning at 120°C for 10 minutes. This was rubbed with 10% sulfuric acid in a conventional manner to expose the surface, and then subjected to dow etching to obtain a letterpress printed image. Table 1 shows the performance of the photosensitive composition obtained. For comparison, a photosensitive solution was prepared in the same manner as in the above example, except that unmodified PVA (saponification degree: 89%, average polymerization degree: 2010) was used instead of the above-mentioned modified PVA. The manufacturing performance was evaluated and shown in Table 1 as Comparative Example 1. A comparison of the performance of Examples and Comparative Examples in the table shows that the photosensitive composition containing the modified PVA of the present invention has excellent photosensitivity and can produce clearer images.

[Table] * Printable line stroke number of positive image obtained after exposure Examples 2 to 5 Example 1 except that various cross-linked group-modified PVAs shown in Table 2 were used instead of the cross-linked group-modified PVA of Example 1. A photosensitive solution was prepared under the same conditions as above, a letterpress printing image was made, and the performance was evaluated. As shown in Table 3, excellent photosensitivity was exhibited and clear images were obtained.

【table】

[Table] Example 11 5%, 3,
An aqueous solution of 3'-dimethoxydiphenyl-4,4'-bisdiazonium chloride zinc chloride double salt prepared at a concentration of 15% based on the modified PVA was applied onto a glass plate in the form of a film with a thickness of 12 μm, and then dried. . After that, a neutral density filter manufactured by Eastman and Kodatsu was placed in close contact with the surface, and ultraviolet rays were irradiated for 30 seconds using a 2KW metal halide lamp kept at a distance of 25 cm, followed by washing for 1 minute with a constant amount of water.
The photosensitivity at this time is shown in Table 4 as a relative value of the exposure amount corresponding to the remaining photosensitive hardening film. For comparison, conventional unmodified PVA (average degree of polymerization: 2000, degree of saponification: 88 mol%) was used to measure the photosensitivity in the same manner as in the examples, and is shown as Comparative Example-2.

[Table] In other words, it can be seen that the photosensitivity is twice as high as that of the conventional photosensitive composition made of PVA. Further, the adhesion of the photosensitive film to the substrate was evaluated by the following method. The photosensitive solutions of the modified PVA of Example 11 and the conventional PVA of Comparative Example 2 were each applied to a glass plate in the form of a 15 μm thick film and dried at 50° C. for 5 minutes. A black plate with 625 circular holes with an inner diameter of 1 mm per 100 cm ² was placed in close contact with the plate and irradiated with ultraviolet light for 30 seconds using a 2KW metal halide lamp kept at a distance of 25 cm, followed by washing with a constant amount of water for 3 minutes. At this time, the remaining circular photoresist film pads were observed and the number of missing dots was determined, as shown in Table 5.

[Table] It can be seen that the photosensitive film made of cationic group-modified PVA of the present invention has better adhesion to the substrate than that made of conventional PVA. Furthermore, while the circles of the photoresist film dots in the examples have a clean shape, those in the comparative examples have noticeable chipped edges and are not clear, indicating that the composition of the present invention can produce clear photosensitive images. Ta. Example 12 30% aqueous solution of crosslinking group-modified PVA with N-n-butoxymethylacrylamide as a copolymerized unit of 0.8 mol%, saponification degree of 81 mol%, and average polymerization degree of 2200.
To 1000 parts, ω- of a photopolymerization initiator was added as an organic photosensitizer.
28 parts of bromoacetophenone and polymerizable monomer β-
A mixed solution of 615 parts of oxyethyl methacrylate was added dropwise and defoamed to prepare a photosensitive composition solution. After casting this photosensitive liquid onto an aluminum plate as a support, it was dried at 60°C in a dryer until the thickness of the photosensitive layer was 1 mm.
Created photosensitive printing plate material. This plate material was left in a carbon dioxide gas stream for 2 to 3 hours, and then exposed to light for 3 minutes in a vacuum frame with a halftone negative attached thereto. A carbon arc lamp with an illuminance of 2000 lux was used as a light source. After exposure, the film was developed using tap water and further dried in a dryer at 100°C for 2 minutes. After drying, the unexposed areas are cured by exposing again to a carbon arc lamp for another 2 minutes. The properties of the resin relief plate obtained are shown in Table 6. For comparison, unmodified PVA (saponification degree: 81
A photosensitive composition and a plate material thereof were prepared in the same manner as in Example 12, except that PVA (mol %, average degree of polymerization: 2200) was used instead of modified PVA. The performance is shown in Table 6 as Comparative Example 3.

[Table] As is clear from the table, it can be seen that an excellent plate material can be made from the photosensitive composition containing the crosslinking group-modified PVA of the present invention.

Claims (1)

[Scope of Claims] A photosensitive composition containing a modified polyvinyl alcohol containing a copolymerized unit represented by the general formula () in one molecule and an organic photosensitizer. (Here, R ¹ is a hydrogen atom or a lower alkyl group,
R ² each represents an alkyl group. 2. The composition according to claim 1, wherein the modified polyvinyl alcohol is a saponified product of a copolymer of N-methoxymethylacrylamide and vinyl acetate. 3. The composition according to claim 1, wherein the modified polyvinyl alcohol is a saponified product of a copolymer of Nn-butoxymethylacrylamide and vinyl acetate.