Photopolymerizable resinous composition

A photopolymerizable resinous composition comprising a photocurable prepolymer having the formula I ##STR5## wherein R.sub.1 is ##STR6## R.sub.2 is --H or --CH.sub.3 R.sub.3 is ##STR7## --CH.sub.2 --CH.sub.2 --, and --CH=CH--, wherein K, L, M, N, O, and P in the formula I, are each mole ratios which satisfy as a group the following conditions:

• K+L+M+N+O+P=0.9-1.1;
• K+L=0.4-0.7;
• M+N=0.3-0.6;
• O+P=0.03-0.3
• wherein said photocurable prepolymer is prepared by the process comprising
• reacting at least one epoxide compound containing at least two epoxy groups with a first unsaturated carboxylic acid containing at least three vinyl linkages having the formula II ##STR8## wherein R.sub.1 is ##STR9## R.sub.3 is ##STR10## --CH.sub.2 --CH.sub.2 --, and --CH=CH--, with a second unsaturated carboxylic acid to form a first reaction product,
• then reacting said first reaction product with a polybasic acid anhydride to form a second reaction product,
• then reacting said second reaction product with a monoepoxide containing one vinyl group to form said photocurable prepolymer,
• wherein said photocurable prepolymer is present in an amount of 40-80 weight percent of said photopolymerizable resinous composition;
• a first photocurable monomer containing one carboxylic acid having the formula II present in an amount of 10-40% by weight of said photopolymerizable resinous composition;
• a second photocurable monomer containing at least one vinyl group present in an amount of 10-30% by weight of said photopolymerizable resinous composition;
• a photopolymerization initiator present in an amount of 0.5-10% by weight of said photopolymerizable resinous composition;
• a curing agent present in an amount of 0.1-15% by weight of said photopolymerizable resinous composition;
• and
• at least one organic solvent present in an amount of 5-60% by weight of said photopolymerizable resinous composition.