JPH0363738B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive composition, particularly a novel photosensitive composition for printing plates suitable for producing flexographic printing plates with good water developability. Two types of photosensitive compositions are known: one in which an organic solvent is used as a developing solution for the photosensitive composition, and the other in a water-developed type in which an aqueous liquid solvent such as an alkaline aqueous solution or a surfactant-containing aqueous solution is used. In the former case, since an organic solvent is used for development, there are problems in terms of pollution control, work environment, etc. On the other hand, in the case of the latter water-developable type, the above-mentioned problems are alleviated, and therefore water-developable photosensitive resins, regardless of whether they are liquid photosensitive resins or solid photosensitive resins, are being actively developed. On the other hand, as printing operations have become faster in recent years, it has been desired to make the curing and developing treatment of photosensitive resin printing plates even faster than before. An object of the present invention is to provide a water-soluble photosensitive composition that has high photocurability and significantly improved water developability. The present invention provides a photosensitive composition comprising a photopolymerization initiator and a prepolymer having two or more terminal groups having a polymerizable ethylenic double bond and n of 800 to 20,000, wherein the prepolymer is (a) an organic Polyisocyanate (A), polyol (B),
At least one tertiary amino group and two
Mn obtained by treating a chain extender (C) having at least 2 active hydrogens and an ethylenically unsaturated compound (D) having active hydrogens with a quaternizing agent (E) is 1,300 to 20,000. (b) organic polyisocyanate (A), a chain extender (C) having at least one tertiary amino group and two or more active hydrogens in the molecule, and active hydrogen per 100 parts by weight of the prepolymer. n800-3000 obtained by treating a compound formed from an ethylenically unsaturated compound (D) with a quaternizing agent (E)
A water-soluble photosensitive composition comprising 5 to 50 parts by weight of a prepolymer. Organic polyisocyanate (A) used in the present invention
Examples include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), isophorone diisocyanate ( IPDI),
Hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI)
and polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate (PAPI). In the present invention, various polyester polyols, polyether polyols, and other polyols can be used as the polyol (B). Examples of polyester polyols include aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as adipic acid, suberic acid, sebacic acid, and brassylic acid, terephthalic acid, and isophthalic acid as acid components, and ethylene glycol, propylene glycol, neopentyl glycol, 1 or more carbon atoms such as hexamethylene glycol
6 aliphatic diols, ether glycols such as diethylene glycol, dipropylene glycol,
Polyester polyols or polycaprolactone polyols containing spiroglycols, N-alkyl dialkanolamines such as N-methyldiethanolamine, etc. as polyol components can be used, and specific examples include polyethylene adipate polyol, polybutylene adipate polyol, and polyethylene. Adipate polyols such as propylene adipate polyol, terephthalic acid polyols (e.g., Toyobo Co., Ltd., product names Vylon RUX, Vylon RV-200L), polycaprolactone polyols (e.g., Daicel Chemical, product names Plaxel 212, Plaxel 220), etc. I can give an example. Specific examples of polyether polyols include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, and the like. In addition, other polyols include polycarbonate polyol (e.g., West Germany, Bayer AG, trade name Desmofene 2020E), polybutadiene polyol (e.g., Nippon Soda, trade name G-1000, G-
2000, G-3000, Idemitsu Petrochemical, product name Poly bd
R-45HT), polypentadiene polyol, castor oil polyol, and the like. As the chain extender (C) in the present invention, a chain extender having at least one tertiary amino group and two or more active hydrogens in the molecule is used. Examples of the above-mentioned chain extenders include N-methyldiethanolamine, N-ethyldiethanolamine, N-butylethanolamine, bis-hydroxyethylpiperazine, and N-phenyldiethanolamine. Further, in the present invention, ordinary chain extenders can be used in combination in addition to the above-mentioned chain extender (C), and preferred examples include those having the general formulas HO-R ¹ -OH, H ₂ NR ² -NH ₂ , A(-CH ₂ CH ₂ OH) ₂ , H ₂ N-B-NH ₂ (R ¹ is a linear or branched alkylene group having 2 to 10 carbon atoms, and may be connected by an oxygen atom. R ² is a carbon A and B are linear or branched alkylene groups or alicyclic groups having numbers 2 to 10.
is a group having an aromatic ring. ) Aliphatic diols, aliphatic diamines, aromatic diols,
Examples include aromatic diamines. Preferred examples of the aliphatic diol include ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, etc., and specific examples of the aliphatic diamine include ethylene diamine, 1,6
-Hexamethylene diamine, isophorone diamine, etc. can be mentioned. Further, as A of the above aromatic diol, for example,

【formula】

【formula】

【formula】

【formula】

【formula】 etc., and as aromatic diamine B,

【formula】

【formula】

[Formula] etc. can be exemplified. In the present invention, a chain extender (C) having at least one tertiary amine group and two or more active hydrogen atoms in the molecule can be copolymerized into polyurethane and then treated with a quaternizing agent. Furthermore, the chain extender may be treated with a quaternizing agent in advance. In the present invention, various types of ethylenically unsaturated compounds (D) having active hydrogen can be used, but representative examples include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, Mono(meth)acrylates of dihydric alcohols such as 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, mono- and di(meth)acrylates of trihydric alcohols such as trimethylolethane, trimethylolpropane, glycerin, etc. ) acrylate, and di- and tri(meth)acrylates of alcohols having a valence of 4 or more, such as pentaerythritol. Examples of the quaternizing agent (E) used in the present invention include dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, alkyl halides such as ethyl bromide, methyl chloride, and methyl iodide, and other various alkyl sulfates such as benzyl chloride. Examples include oxidizing agents. The prepolymer (a) of the present invention can be obtained by various methods. For example, organic polyisocyanates
A terminal NCO prepolymer is synthesized from (A) and a polyol (B), and an ethylenically unsaturated compound (D) having active hydrogen in an amount equivalent to half of the terminal NCO groups is reacted with the prepolymer, and then the remaining NCO groups are A method in which a corresponding amount of chain extender (C) is reacted and then treated with a quaternizing agent (E), or a method in which (A) and (D) are reacted first to form a terminal
Synthesize the NCO prepolymer and then proceed similarly (B).
A method of reacting with components (C) and (E), and further synthesis of terminal NCO prepolymers from (A) and (B) and (A) and (D), respectively, and a mixture of these two types of prepolymers. (C),
(E) A method of reacting the component can be exemplified. When producing the prepolymer (a) of the present invention, the proportions of each component can be appropriately determined from a wide range depending on the desired photosensitive composition, but usually polyol (B), chain extender (C), and compound (D ) and the NCO group of compound (A) are preferably reacted in a range of 0.9 to 1.4, preferably 0.95 to 1.2, and the reaction is usually carried out at 30 to 130°C, preferably is 40~120
It is best to do it at ℃. Further, it is preferable that the treatment with the quaternizing agent of the present invention is usually carried out at a temperature in the range of 40 to 100°C.
The prepolymer (a) of the present invention obtained as described above preferably has n in a range of 1,300 to 20,000. The prepolymer (b) of the present invention is formed from an organic polyisocyanate, a chain extender having at least one tertiary amino group and two or more active hydrogens in the molecule, and an ethylenically unsaturated compound having active hydrogens. It can be obtained by treating the same with a quaternizing agent. As the above-mentioned organic polyisocyanate, chain extender and ethylenically unsaturated compound, the compounds (A), (C) and (D) mentioned above for the prepolymer (a) can be used. n of prepolymer (b) is 800
A range of ~3000 is preferred. Prepolymer (b) can be obtained by various methods, for example, organic polyisocyanate (A) and ethylenically unsaturated compound (D).
Synthesize a terminal NCO prepolymer by reacting
Examples include a method in which a chain extender (C) is then reacted, followed by treatment with a quaternizing agent (E). When producing the prepolymer (b) of the present invention, the proportions of each component can be appropriately determined from a wide range depending on the intended photosensitive composition, but the active hydrogen contained in the chain extender and compound (D) is usually group and compound (A)
The chemical equivalent ratio of NCO groups is 0.9-1.4, preferably 0.95
-1.2, and the reaction is usually carried out at 30 to 130°C, preferably 40 to 120°C. In the present invention, prepolymer (a) and prepolymer (b) can be synthesized without a solvent, in the presence of an organic solvent, or in the presence of an ethylenically unsaturated compound used as a crosslinking agent, which will be described later. Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and methyl propionate, ethers such as dioxane and cellosolve acetate, and dimethylformamide and dimethyl sulfoxide. In the present invention, prepolymer (a) and prepolymer
The ratio of (b) can be selected from a wide range, but the ratio of the former
When the latter is in the range of 5 to 50 parts by weight per 100 parts by weight, various properties such as photocurability, strength of the cured product, and plate-making properties are excellent. Although the reason for this is not clear, it is presumed that the quaternized amino group promotes the excitation of ethylenically unsaturated double bonds. When photocuring the prepolymer of the present invention, an ethylenically unsaturated compound is used as a crosslinking agent. Various known compounds can be used as the ethylenically unsaturated compound, but representative examples include styrene, vinyltoluene, chlorostyrene, t-butylstyrene, α-methylstyrene,
divinylbenzene, acrylic acid, methacrylic acid,
Methyl, ethyl, isopropyl, n-butyl, t-butyl, α of acrylic acid or methacrylic acid
- Ethylhexyl, n-nonyl, n-decyl, lauryl, stearyl ester, etc., n-butoxyethyl acrylic acid or methacrylic acid, cyclohexyl, phenoxyethyl, tetrahydrofurfuryl, glycidyl, allyl, benzyl, tribromophenyl, 2,3 -dichloropropyl, 3-
Chloro-2-hydroxypropyl, N,N-dimethylaminoethyl, N,N-diethylaminoethyl, N-t-butylaminoethyl ester, etc., ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate,
Diethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate with a molecular weight (hereinafter referred to as MW) of 200 to 1000, polyethylene glycol monomethyl ether mono(meth)acrylate with a MW of 200 to 1000,
Polypropylene glycol mono(meth)acrylate with MW200-1000, polypropylene glycol monomethyl ether mono(meth)acrylate with MW200-1000, polyethylene glycol monoethyl ether mono(meth)acrylate with MW200-1000, polypropylene glycol monoethyl ether with MW200-1000 Mono(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate (meta)
Acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, glycerin di(meth)acrylate, glycerin tri(meth)acrylate, trimethylolethane di(meth)acrylate, ) acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, ethylenebisacrylamide, diallylphthalate, triallylisocyanurate, dibutyl Examples include fumarate and vinyl acetate. Among the above crosslinking agents, especially the general formula (R is hydrogen, methyl or ethyl, and n is 2 to 10) When an ethylenically unsaturated compound is used, it has extremely excellent impact resilience and elastic recovery rate, has good water developability, and has excellent photoresist properties. This is preferable because a flexographic printing plate with excellent curability can be obtained. The polyoxyethylene difference between the above compounds not only had a significant effect on the basic physical properties of the composition, but also had good washout properties and water resistance of the cured product. In the present invention, the crosslinking agent is 100% of the total prepolymer.
A range of 150 parts by weight or less, preferably 100 parts by weight or less based on the weight part is used, and among these, the above general formula (1)
The crosslinking agent is 5 parts by weight per 100 parts by weight of the total prepolymer.
Particularly preferred is a range of 40 parts by weight. Incidentally, among the above-mentioned crosslinking agents, ethylenically unsaturated compounds having active hydrogen should be excluded if they are present during the urethanization reaction. Even in this case, it is preferable to use the crosslinking agent in such a range that the final amount of crosslinking agent used is 150 parts by weight or less based on 100 parts by weight of the total prepolymer, and the entire amount may be used at the time of urethanization. It's okay to be a part of it. Various known compounds can be used as the photopolymerization initiator of the present invention, such as benzoin, benzoin ethyl ether, benzoin propyl ether,
0.001 to 10% by weight of benzoin alkyl ethers such as benzoin butyl ether, dimethoxyphenylacetophenone, benzophenone, benzyl, diacetyl, diphenyl sulfide, eoxy, thionine, etc. based on the total amount of the prepolymer and crosslinking agent, preferably can be used in a range of 0.01 to 5% by weight. A known thermal polymerization inhibitor may be added for the purpose of stably storing the photosensitive composition of the present invention. For example, hydroquinone, mono-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, hydroquinone monomethyl ether, catechol, p-tert-butylcatechol, benzoquinone, 2,5-di-tert-butylbenzoquinone, , 5-diphenyl-p-benzoquinone, 2,6-di-tert-butyl-p-cresol, and picric acid. It is desirable that these thermal polymerization inhibitors prevent only the thermal polymerization reaction (dark reaction) without inhibiting the photocuring reaction, and therefore the amount added is 0.001% of the total amount of the prepolymer and crosslinking agent. A range of 2.5% by weight, preferably 0.005% to 1% by weight is desirable. The photosensitive composition of the present invention can be cured by a known method, for example, it is appropriate to use an active light source with a wavelength of 200 to 700 nm. The active light source may be appropriately selected depending on the type of photopolymerization initiator, and for example, sunlight, low pressure, high pressure or ultra-high pressure mercury lamp, carbon arc lamp, xenon lamp, tungsten lamp, etc. can be used. Further, in the present invention, other curing means may be employed, such as heat curing, that is, curing using radiation mainly consisting of thermal energy such as infrared rays, high frequency waves, or microwaves, or curing using ionizing radiation such as electron beams or gamma rays. can. Suitable polymerization initiators in such cases include, for example, ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, hydroperoxides such as cumene hydroperoxide and tert-butyl peroxide, di-
Dialkyl peroxides such as tert-butyl peroxide and dicumyl peroxide, tert
Examples include peroxy esters such as -butyl peroxylaurate and tert-butyl peroxybenzoate, and azo compounds such as azobisisobutyronitrile. Further, polymerization accelerators such as metal soaps such as cobalt and manganese for the above-mentioned ketone peroxides, or reducing amines for the above-mentioned hydroperoxides can also be used. Furthermore, when using high-energy ionizing radiation that has the effect of being absorbed by substances such as the above-mentioned electron beams and γ-rays and emitting secondary electrons, it may be used alone or in combination with irradiation from the active light source. does not require the addition of an initiator, but may contain a photopolymerization initiator or a thermal polymerization initiator as described above. The photosensitive composition of the present invention can be printed by applying the above-mentioned active light source to a suitable negative film, exposing it to form a relief image, and washing out the unexposed areas using a suitable solvent. You can get the version. Examples of such solvents include aqueous solvents such as alkaline aqueous solutions, neutral detergent aqueous solutions, and alcohol/water mixtures, and organic solvents such as methanol, ethanol, and acetone. can be sufficiently developed using only water. Although the photosensitive composition of the present invention has extremely excellent photocurability, it can also be provided with any photocurability depending on the application. Furthermore, the cured product of the photosensitive composition of the present invention has excellent not only mechanical strength but also particularly adhesive properties, and can be used as a printing plate as it is by using a backing material such as rubber from the time of curing. . The photosensitive composition of the present invention is mainly suitable for producing flexographic printing plates, but can also be used as various elastomers that are cured by active light sources, such as paints, coating materials, adhesives, film sheet forming agents, and other molded products. It can also be used for A detailed explanation will be given below with reference to synthesis examples and examples. Synthesis Example 1 Synthesis of prepolymer (a) 300 g of polyethylene adipate with a molecular weight of 1000 and 133.2 g of isophorodiisocyanate were placed in a reactor equipped with a stirring device, and reacted at 80°C for 3 hours, and then 34.8 g of 2-hydroxyethyl acrylate and dibutyltin dilaurate were added. After dropping 0.04 g of the mixture and reacting for 2 hours and 30 minutes until no OH absorption was detected in the infrared absorption spectrum (IR), N-
Gradually add a mixture of 11.9 g of methyldiethanolamine and 4.5 g of 1,4-butanediol and add the mixture under IR.
The reaction was allowed to proceed for 1 hour and 10 minutes until no NCO absorption was detected. After cooling to 60°C, 124.26 g of 2-hydroxyethyl acrylate, 12.6 g of dimethyl sulfate
A mixture of 0.6 g of prepolymer (a) and 0.6 g of hydroquinone was gradually added to obtain a solution () containing 80% by weight of prepolymer (a). Synthesis Example 2 Synthesis of prepolymer (a) (a) 2,4-TDI 624.2g (b) 2-hydroxyethyl acrylate (ethylene glycol monoacrylate) 416.4g (c) Dibutyltin dilaurate 0.10g Reactor with stirring device (a) ) and heated to 50°C. While maintaining this temperature, a mixture of components (b) and (c) was added dropwise over 2 hours and 20 minutes. The reaction was carried out for 1 hour and 50 minutes to obtain an intermediate (P ₁ ). (d) 2,4-TDI 386.9g (e) PEG-1000 1123.8g (f) Dibutyltin dilaurate 0.15g After placing component (d) in a separate reactor equipped with a stirring device and heating to 70°C, (e) A mixture of components (f) and (f) was gradually added, and the mixture was allowed to react for about 2 hours and 40 minutes until no OH absorption was detected by IR to obtain an intermediate (P ₂ ). Then (g) Intermediate (P ₁ ) 544.7g (h) Intermediate (P ₂ ) 1394.4g (i) N-methyldiethanolamine 234.0g (j) Dimethyl sulfuric acid 208.8g New reactor with stirring device (g) and (h) Add ingredients
After heating to 50℃, component (i) was added while maintaining this temperature, and the reaction was allowed to take place for 2 hours and 30 minutes until no NCO absorption was detected by IR. After that, component (j) and 595.5 g of tetrahydrofurfuryl acrylate were added. A mixture of 3 g of hydroquinone and 3 g of hydroquinone was gradually added, and after the addition, the reaction was continued for another 30 minutes to obtain a solution (2) containing 80% by weight of prepolymer (a). Synthesis Example 3 Synthesis of prepolymer (b) 261 g of the intermediate (P ₁ ) obtained in Synthesis Example 2 was placed in a reactor equipped with a stirring device and heated to 70°C, and then 53.5 g of N-methyldiethanolamine was added dropwise. At IR
The reaction was continued for 1 hour and 50 minutes until the absorption of NCO was no longer detected, and after cooling to 60°C, dimethyl sulfate 60.7
g, tetrahydrofurfuryl acrylate 93.9g
A mixture of 0.47 g of hydroquinone and 0.47 g of prepolymer (b) was gradually added and reacted for 30 minutes after the addition to obtain a solution () containing 80% by weight of prepolymer (b). Synthesis Example 4 Synthesis of Prepolymer (a) Intermediate (P3) was obtained in the same manner as in Synthesis Example 2 except that pentaerythritol dimethacrylate was used instead of 2-hydroxyethyl acrylate. Subsequently, in Synthesis Example 2, the above intermediate (P3) was used instead of intermediate (P2), and N-phenyldiethanolamine was used instead of N-methyldiethanolamine.
In the same manner as in Synthesis Example 2 to synthesize the prepolymer
A solution () containing 80% by weight of (a) was obtained. Synthesis Example 5 Synthesis of prepolymer (b) Using the intermediate (P3) obtained in Synthesis Example 4 and N-phenyldiethanolamine, prepolymer
A solution () containing 80% by weight of prepolymer (b) was obtained in the same manner as in Synthesis Example 3 for synthesizing (b). Example 1 60g of the solution obtained in Synthesis Example 1 and Synthesis Example 3
1.5 g of benzoin methyl ether, 5 g of tetrahydrofurfuryl acrylate, and 10 g of polyethylene glycol dimethacrylate (molecular weight: about 330) were added to 30 g of the solution () obtained in step 1, and thoroughly mixed to obtain a photosensitive composition (1). When the photosensitive composition (1) was irradiated from a distance of 30 cm using a 500W high-pressure mercury lamp, it was able to be completely cured in 1.5 minutes. The physical properties of the obtained cured product were as follows. Tensile strength 83Kg/cm ² Hardness (Shore A) 58 Elongation 185% Impact resilience 43% Example 2 Pour the photosensitive composition (1) obtained in Example 1 above onto a polyester film, and cover it with a thin polyester film. After covering with a film, apply a negative film and light it with a 500W high pressure mercury lamp from a distance of 30cm.
The image was formed by irradiation for a minute. Next, the cover film was removed, and the exposed photosensitive master plate was washed and developed in a hot water bath at 60°C. As a result, the plate was successfully developed without any uncured resin adhering to the relief surface, and a plate with a relief depth of 3 mm was obtained. . The time required for development was 5 minutes. Example 3 60g of the solution obtained in Synthesis Example 2 and Synthesis Example 3
1.5 g of benzoin methyl ether, 4 g of diethylene glycol monomethacrylate, and 10 g of polyethylene glycol diacrylate (molecular weight: about 522) were added to 25 g of the solution (2) obtained in step 1 and thoroughly mixed to obtain a photosensitive composition (2). When the photosensitive composition (2) was cured in the same manner as in Example 1, it was completely cured in 1.2 minutes. The physical properties of the obtained cured product were as follows. Tensile strength 72Kg/cm ² Hardness (Shore A) 47 Elongation 205% Impact resilience 48% Example 4 The photosensitive composition (2) obtained in Example 3 above was imaged and developed in the same manner as in Example 2. When this was carried out, a plate with a relief depth of 2 mm was obtained, which could be developed neatly without any uncured resin adhering to the relief surface. The time required for development was 3 minutes. Example 5 60 g of the solution obtained in Synthesis Example 4 and Synthesis Example 5
1.5 g of dimethoxyphenylacetophenone, 10 g of 2-hydroxyethyl methacrylate, and 12 g of polyethylene glycol dimethacrylate (molecular weight, approximately 418) were added to 20 g of the solution () obtained in step 2, and mixed thoroughly to form a photosensitive composition (6). ) was obtained. When the photosensitive composition (6) was cured in the same manner as in Example 1, it was completely cured in 1.2 minutes. The physical properties of the obtained cured product were as follows. Tensile strength 96Kg/cm ² Hardness (Shore A) 50 Elongation 200% Impact resilience 47% Example 6 In Synthesis Example 1, for N-methyldiethanolamine, which is a component containing an amino group in prepolymer (a), Quaternization with dimethyl sulfate
A photosensitive composition with the same formulation as in Example 1 was prepared using a solution () obtained by performing the same synthesis in advance before addition of phenyldiethanolamine, and a comparison of physical properties and image formation was carried out. When tested, almost the same physical properties were measured, and sufficient adhesive strength was exhibited with no problems with the rubber material. Comparative Example 1 In Synthesis Examples 1 to 3, prepolymer solutions that were not treated with the quaternizing agent (dimethyl sulfuric acid) were synthesized using the same procedure, and each solution was converted into ('),
(′), (′). A photosensitive composition (3) was prepared by using the same 30 g of the prepolymer solution (') as the above 60 g and replacing the prepolymer solutions () and () shown in Example 1 with the other components in the same manner. I got it. When the photosensitive composition (3) was cured in the same manner as in Example 1, it took 10 minutes to completely cure. Comparative Example 2 When image formation and development were performed using the photosensitive composition (3) in Comparative Example 1 for an irradiation time of 12 minutes under the same conditions as in Example 2, a considerable amount of light was observed on the relief surface. Some uncured resin remained, and even with a processing time of 10 minutes, uneven development was observed throughout the plate.
In particular, the relief images of fine print and detailed designs were unclear. Comparative Example 3 Prepolymer solution (') obtained in Comparative Example 1
A photosensitive composition (4) was obtained using 60 g and 25 g of (') in place of the prepolymers () and () shown in Example 3, and using the same procedures except for the other components. When the photosensitive composition (4) was cured under the same conditions as in Example 1, it took 8 minutes to completely cure. Comparative Example 4 Using the photosensitive composition (4) in Comparative Example 3 above, image formation and development were performed under the same conditions as in Example 2 except for an irradiation time of 10 minutes. Unevenness occurred, and the development was insufficient, especially in areas with intricate characters and images. Comparative Example 5 Composition obtained in the same manner as in Example 1 except that solution () was completely replaced with solution ()
When (5) was similarly cured, it took 4 minutes to completely cure. Furthermore, when an attempt was made to form an image using composition (5), due to its high viscosity, a considerable amount of time and care were required to obtain an original plate free of air bubbles. When the compositions of Comparative Example 5 and Example 1 were poured into a film on a rubber backing material and cured, in Example 1, there was no peeling between the rubber backing material and the rubber backing material.
Although peeling did not occur and sufficient adhesive strength was exhibited, in Comparative Example 5, peeling and peeling occurred. Comparative Example 6 In Example 1, all solution () was replaced with solution ()
The physical properties of the cured product were measured for a composition obtained in the same manner except that the composition was replaced with . Tensile strength is 121
Kg/cm ² , elongation 43%, rebound resilience 71%, and hardness (Shoer A) 78.The cured product has poor toughness, and when used as a plate, the edges of the relief may chip, resulting in insufficient durability. It was hot. Comparative Example 7 Using the solution (') of prepolymer (b) obtained in Comparative Example 1, which was not treated with the quaternizing agent (dimethyl sulfate), in place of the solution () of Example 1, Example When a photosensitive composition having the same formulation as Example 1 was prepared and cured in the same manner as in Example 1, it took 6 minutes to completely cure. The physical properties of the obtained cured product were as follows. Tensile strength 76Kg/cm ² Hardness (Shore A) 55 Elongation 165% Impact resilience 44% Also, when image formation and development were performed in the same manner as in Example 2, uncured resin remained on a part of the relief surface and the surface was completely It took a total of 8 minutes to remove the uneven development. By using the prepolymer (b) treated with a quaternizing agent (dimethyl sulfate) as described above,
It is effective in (1) improving water developability during image formation, (2) reinforcing the physical properties of the printing plate after image formation, and (3) improving photocurability, and when quaternization is not performed. The effect of improving these properties is insufficient.

Claims (1)

[Scope of Claims] 1. A photosensitive composition comprising a prepolymer having two or more terminal groups having a polymerizable ethylenic double bond and having n of 800 to 20,000 and a photopolymerization initiator,
The prepolymer is (a) an organic polyisocyanate (A), a polyol (B),
At least one tertiary amino group and two
From a chain extender (C) having more than 1 active hydrogen and an ethylenically unsaturated compound having active hydrogen (D)
The n obtained by treating the reaction composition with an NCO index of 0.9 to 1.4 with a quaternizing agent (E) is 1300.
-20,000 per 100 parts by weight of the prepolymer (b) an organic polyisocyanate (A), a chain extender (C) having at least one tertiary amino group and two or more active hydrogen atoms in the molecule; NCO Index 0.9~ from ethylenically unsaturated compounds (D) containing hydrogen
The one formed with the reaction composition of 1.4 is the quaternizing agent (E).
and (c) an ethylenically unsaturated compound as a crosslinking agent in an amount of 5 to 150 parts by weight based on 100 parts by weight of the total prepolymer. [The chain extender (C) is N-methyldiethanolamine,
A compound selected from N-ethyldiethanolamine, N-butyldiethanolamine, bis-hydroxyethylpiperazine, and N-phenyldiethanolamine, and the ethylenically unsaturated compound (D) having active hydrogen is a dihydric alcohol mono(meth) It is a compound selected from acrylates, mono- and di(meth)acrylates of trihydric alcohols, and di- and tri(meth)acrylates of tetrahydric alcohols. ]. 2 General formula as a crosslinking agent Claim 1 obtained by adding 5 to 40 parts by weight of an ethylenically unsaturated compound represented by (R is hydrogen, methyl or ethyl, and n is 2 to 10) to 100 parts by weight of the prepolymer. Compositions as described.