JPH049294B2 - - 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 a flexographic printing plate with good water developability. Two types of photosensitive compositions are known: one type uses an organic solvent as a developer, and the other type uses an aqueous solvent such as an alkaline aqueous solution or a surfactant-containing aqueous solution. 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 photosensitive composition that has high photocurability and significantly improved water developability. Another object of the present invention is to provide a low-hardness photosensitive composition that can be printed on objects with rough and wavy surfaces, such as cardboard. The present invention provides a photosensitive composition containing a photopolymerization initiator and a prepolymer having two or more end groups having a polymerizable ethylenic double bond and n of 1,300 to 20,000, wherein the prepolymer is (a) an organic A polyisocyanate (A), a polyol (B) if necessary, a chain extender (C) having at least one tertiary amino group and two or more active hydrogens in the molecule, and an ethylenic inorganic resin having active hydrogens. 30-90% by weight of the prepolymer obtained by treating the one formed from the saturated compound (D) with the quaternizing agent (E)
and (b) a prepolymer formed from an organic polyisocyanate (A), a polyethylene glycol having two or more active hydrogen terminals and n of 5000 or less, and an ethylenically unsaturated compound having an active hydrogen (D).
It relates to a low-hardness water-developable photosensitive composition characterized in that the composition contains 10 to 70% by weight. 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
bdR-45HT), polypentadiene polyol,
Examples include castor oil-based polyols. 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-butyldiethanolamine, bis-hydroxyethylpiperazine, and N-phenyldiethanolamine. Further, in the present invention, ordinary chain extenders can be used in combination in addition to the above chain extender (C), and preferred examples include those having the general formula HO-R-OH, H ₂ N-R'-NH ₂ , A-(CH ₂ CH ₂ OH) ₂ , H ₂ N-B-NH ₂ , (R is a linear or branched alkylene group having 2 to 10 carbon atoms, and may be connected by an oxygen atom. R' is a carbon Aliphatic diol, aliphatic diamine, aromatic diol, aromatic diol, aliphatic diol, aliphatic diamine, aromatic diol, aromatic diol, a linear or branched alkylene group or alicyclic group having a number of 2 to 10.A and B are groups having an aromatic ring. Examples include group 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 the aromatic diamine B,

【formula】

【formula】

[Formula] etc. can be exemplified. In the present invention, a chain extender (C) having at least one tertiary amino group and two or more active hydrogen atoms in the molecule can be copolymerized into polyurethane and then treated with a quaternizing agent. Moreover, the above chain extender can also 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 propolymer (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), reacting (A) and (D) to synthesize a terminal NCO prepolymer, and then (C),
(E) A method of reacting with component, and furthermore, (A) and (B) and (A)
Synthesize terminal NCO prepolymers from (D),
Examples include a method of reacting components (C) and (E) with a mixture of these two types of prepolymers. 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 (b) of the present invention is an organic polyisocyanate, having two or more active hydrogen atoms at the terminals and n
5000 or less polyethylene glycol (hereinafter referred to as PEG)
) and ethylenically unsaturated compounds with active hydrogen. As the organic polyisocyanate and the ethylenically unsaturated compound having active hydrogen, the compounds (A) and (D) mentioned above for the prepolymer (a) can be used. Prepolymer (b) can be obtained by various methods, for example, by combining organic polyisocyanate (A) with
A method of reacting PEG to synthesize a terminal NCO prepolymer and reacting it with an ethylenically unsaturated compound (D). Synthesizing a terminal NCO prepolymer from (A) and (D) and reacting it with PEG. method, or (A),
Examples include a method in which PEG and (D) are reacted simultaneously. 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 usually PEG and the compound
Active hydrogen group contained in (D) and NCO of compound (A)
The chemical equivalent ratio of the groups is 0.9 to 1.4, preferably 0.95 to 1.2
It is best to react within the range of 30
It is good to carry out at ~130°C, preferably 40-120°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
Although the proportion of (b) can be selected from a wide range, it is particularly preferable to make the prepolymer (a) 30 to 90% by weight based on the total prepolymer since various properties such as photocurability are excellent. The reason for this is not clear, but the quaternized amino group is ethylenically unsaturated.
It is presumed that this is to promote the excitation of heavy bonds. When photocuring the prepolymer of the present invention, an ethylenically unsaturated compound can be used as a crosslinking agent if necessary. Various known compounds can be used as ethylenically unsaturated compounds, but typical examples include styrene, vinyltoluene, chlorostyrene, t-butylstyrene, α-methylstyrene, vinylbenzene, acrylic acid, and methacrylic acid. , acrylic acid or methacrylic acid methyl, ethyl, isopropyl, n-butyl, t-
Butyl, α-ethylhexyl, n-nonyl, n-
Decyl, lauryl, stearyl esters, 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, molecular weight (hereinafter referred to as MW)
200-1000 polyethylene glycol mono(meth)
Acrylate, polyethylene glycol monomethyl ether mono(meth)acrylate with MW200-1000, polypropylene glycol mono(meth)acrylate with MW200-1000, MW200-1000
Polypropylene glycol monomethyl ether mono(meth)acrylate, MW200~1000 polyethylene glycol monoethyl ether mono(meth)acrylate, MW200~1000 polypropylene glycol monoethyl ether 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, 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, trimethylolethane tri(meth)acrylate, Methylolpropane tri(meth)acrylate, acrylamide,
Examples include N,N-dimethylacrylamide, N,N-diethylacrylamide, ethylenebisacrylamide, diallyl phthalate, triallyl isocyanurate, dibutyl fumarate, and vinyl acetate. Among the above crosslinking agents, especially the general formula (R ¹ is hydrogen, methyl, or ethyl, R ² is hydrogen, methyl, ethyl, or halomethyl, and n is 2 to 10). This is preferable since it is possible to obtain a flexographic printing plate that has a high curability, good water developability, and excellent photocurability. The polyoxyalkylene chain of the above compound 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)
5 parts of crosslinking agent per 100 parts by weight of 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, eosin, 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, 2,5-di-tert-butylhydroquinone, Examples include -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 azobisisobutylnitrile. 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 perform sufficiently good development using only an aqueous solvent. In particular, as a crosslinking agent, for example, a compound in which R ² is hydrogen among the compounds of the general formula (1), or a water-soluble compound such as ethylene glycol mono (meth) acrylate (2-hydroxyethyl meth) acrylate, tetrahydrofurfuryl (meth) acrylate, etc. In photosensitive compositions using crosslinking agents, development after curing can surprisingly be carried out using only water. In addition, the photosensitive composition of the present invention has extremely excellent photocurability, but it can be applied to any photocurability depending on the application, and since it has low hardness, it can be used for objects such as cardboard with rough and wavy surfaces. You can also print on things. 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 molding applications. It can also be used for products etc. A detailed explanation will be given below with reference to synthesis examples and examples. Synthesis Example 1 Synthesis of prepolymer (a) (a) 2,4-TDI 312.2g (b) 2-hydroxyethyl acrylate (ethylene glycol monoacrylate) 208.2g (c) Dibutyltin dilaurate 0.052g In a reactor equipped with a stirring device ( Add component a), heat to 50℃, and dropwise add the mixture of components (b) and (c) over 2 hours and 20 minutes while maintaining this temperature. The reaction was allowed to proceed for approximately 1 hour and 50 minutes until no absorption was detected, yielding 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 reacted 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 ) 544.7 g (h) Intermediate (P ₂ ) 1394.4 g (i) N-methyldiethanolamine 234.0 g (j) Dimethyl sulfuric acid 208.8 g Into a new reactor with stirring device (g) Add component (h) and heat to 50℃, then add component (i) while maintaining this temperature and react for 2 hours and 30 minutes until no NCO absorption is detected by IR, then add component (j). A mixture of 595.5 g of tetrahydrofurfuryl acrylate and 3 g of hydroquinone was gradually added, and after the addition, the reaction was continued for another 30 minutes to obtain a solution () containing 80% by weight of prepolymer (a). Synthesis Example 2 Synthesis of prepolymer (a) 300 g of polyethylene adipate with a molecular weight of 1000 and 133.2 g of isophorone diisocyanate were placed in a reactor equipped with a stirring device, and reacted at 80°C for 3 hours, followed by 34.8 g of 2-hydroxyethyl acrylate and 0.04 g of dibutyltin dilaurate. After adding dropwise a mixture of 1.g and 2 hours and 30 minutes until no OH absorption was detected by IR, a mixture of 11.9 g of N-methyldiethanolamine and 4.5 g of 1,4-butanediol was gradually added and the mixture was subjected to IR. The reaction was allowed to proceed for 1 hour and 10 minutes until no NCO absorption was detected. After cooling to 60℃, 2-hydroxyethyl acrylate
124.26 g, dimethyl sulfate 12.6 g and hydroquinone 0.6 g were gradually added to prepare the prepolymer.
A solution () containing 80% by weight of (a) was obtained. Synthesis Example 3 Synthesis of prepolymer (b) 129g of 2,4-TDI was placed in a reactor equipped with a stirring device, heated to 50℃, and while maintaining this temperature.
After dropping a mixture of 374.6 g of PEG1000 (molecular weight 1000) and 0.05 g of dibutyltin dilaurate, it was heated to 80°C and reacted for 3 hours, and after confirming by IR that absorption of active hydrogen was no longer detected, Furthermore, a mixture of 86 g of 2-hydroxyethyl acrylate and 0.06 g of dibutyltin dilaurate was added dropwise, and the IR
2 hours until no NCO absorption is detected at
After reacting for 30 minutes, 0.6 g of hydroquinone was finally added to obtain prepolymer (b). Comparative Example 1 1.5 g of benzoin methyl ether, 10 g of 2-hydroxyethyl acrylate, and 15 g of polyethylene glycol dimethacrylate (molecular weight approximately 330) were added to 60 g of the solution () obtained in Synthesis Example 1 and mixed thoroughly to prepare a photosensitive composition. I got it. The above photosensitive composition was heated using a 500W high pressure mercury lamp.
When irradiated from a distance of 30 cm, it was able to be completely cured in 2 minutes. The properties of the obtained cured product were as follows. Tensile strength 60Kg/cm ² Hardness (Shore A) 42 Elongation 205% Impact modulus 58% Reference example 1 The photosensitive composition obtained in Comparative Example 1 above was poured onto a polyester film, and a thin polyester film was placed on top of it. After covering, a negative film was applied and an image was formed by irradiating it with a 500W high-pressure mercury lamp from a distance of 30cm for 3 minutes. Next, the cover film was peeled off, and the exposed photosensitive original plate was washed and developed in a hot water bath at 60°C. The plate was successfully developed without any uncured resin adhering to the relief surface, and a plate with a relief depth of 2 mm was obtained. Ta. The time required for development was 5 minutes. Comparative Example 2 and Examples 1 to 2 A photosensitive composition was prepared using the solution () obtained in Synthesis Example 2 and the prepolymer (b) obtained in Synthesis Example 3, and the composition was prepared in the same manner as in Comparative Example 1. Various properties of the cured product were measured. For the photosensitive composition, the amount listed in Table 1 was used so that the total solid content of the prepolymer was 50 g, and in addition, 1.0 g of benzoin methyl ether was added.
and a crosslinking agent in the amount shown in Table 1.

[Table] In addition, (a) is 2-hydroxyethyl acrylate,
(B) is styrene, and (C) is n-butyl acrylate. (d) is polyethylene glycol diacrylate and has a molecular weight of 522. Curing time refers to the time required for complete drying to the touch. Reference Examples 2 to 4 When the photosensitive compositions of Comparative Example 2 and Examples 1 to 2 were subjected to the same development treatment as in Example 2 using an aqueous surfactant solution, the relief surface improved in all cases within 5 minutes. It was possible to develop the image cleanly without any uncured resin adhering to it. Comparative Examples 3-4 Photosensitive compositions were prepared under the same conditions as in Examples 1-2 except that the proportions of prepolymer (a) and prepolymer (b) were outside the claimed range, and their The various properties are compared in Table 1. Both curability and strength were lower than those of the Examples, and when used as a printing plate, the durability was insufficient. Reference Examples 5 to 7 A solution containing prepolymer (a)' was synthesized using the same procedure as in Synthesis Example 2, except that the treatment with the quaternizing agent was not performed, and the photosensitivity used in Reference Examples 2 to 4 was When prepolymer (a) in the composition was replaced with the above-mentioned non-quaternized prepolymer (a)', and the other conditions were the same, evaluations were conducted in the same manner as in Reference Examples 2 to 4. When using a so-called aqueous solvent containing an aqueous solution, a considerable amount of uncured resin remained on the surface of the relief and it was not possible to develop it neatly. In particular, in Reference Example 5, most of the uncured resin remained attached to the relief surface, which did not meet the object of the present invention at all. Comparative Example 5 170.5 g of 2,4-TDI, 491.2 g of polyethylene adipate (PEA, molecular weight 1000), and 0.07 g of dibutyltin dilaurate were mixed and stirred at 80° C. for 3 hours to obtain a prepolymer with NCO at both ends. Next, a mixture of 113.7 g of 2-hydroxyethyl acrylate and 0.08 g of dibutyltin dilaurate was added dropwise to the mixture, and the mixture was reacted at 60° C. for 2.5 hours. 0.8 g of hydroquinone was added to this to obtain prepolymer (b'). A photosensitive composition prepared in the same manner as in Examples 1 and 2 except that the above prepolymer (b') was used instead of prepolymer (b) was developed using a surfactant. However, a considerable amount of uncured resin remained on the relief surface, and only an unclear image was obtained. Comparative Example 6 Prepolymer (b″) was obtained in the same manner as in Comparative Example 5, except that polypropylene glycol was used instead of polyethylene adipate. In Examples 1 and 2, the above prepolymer (b) was used instead of prepolymer (b). When the cured product was developed using a surfactant for a photosensitive composition prepared in the same manner except that (b″) was used, a considerable amount of uncured resin remained on the relief surface, leaving an indistinct All I could get was an image.

Claims (1)

[Scope of Claims] 1. 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 1,300 to 20,000, wherein the prepolymer is (a) Organic polyisocyanate (A), polyol (B) if necessary, chain extender (C) having at least one tertiary amino group and two or more active hydrogens in the molecule, and active hydrogen. 30 to 90% by weight of the prepolymer obtained by treating the ethylenically unsaturated compound (D) with the quaternizing agent (E)
and (b) a prepolymer formed from an organic polyisocyanate (A), a polyethylene glycol having two or more active hydrogen terminals and n of 5000 or less, and an ethylenically unsaturated compound having an active hydrogen (D).
A low hardness water-developable photosensitive composition characterized by comprising 10 to 70% by weight [chain extender (C) is N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, bis-hydroxyethylpiperazine and It is a compound selected from N-phenyldiethanolamine, and the ethylenically unsaturated compound (D) having active hydrogen is mono(meth)acrylate of dihydric alcohol, mono- and di(meth)acrylate of trihydric alcohol, and tetrahydric alcohol. It is a compound selected from di- and tri(meth)acrylates of alcohols. ]. 2 General formula (R ¹ is hydrogen, methyl or ethyl, R ² is hydrogen, methyl, ethyl or halomethyl, n is 2 to 10). 2. The photosensitive composition according to claim 1, which is obtained by adding a part of the photosensitive composition according to claim 1.