Butadiene/acrylonitrile photosensitive, elastomeric polymer compositions for flexographic printing plates

A photosensitive, elastomeric composition which comprises, based on the total composition,

• (a) 55 to 85% by weight of a high molecular weight butadiene/acrylonitrile copolymer having a number average molecular weight of 20,000 to 75,000, an acrylonitrile content of 10 to 50% by weight, and a carboxyl content of 1 to 15% by weight;
• (b) 5 to 40% by weight of a low molecular weight butadiene polymer having a number average molecular weight of 750 to 10,000, an acrylonitrile content of 0 to 50% by weight, and a carboxyl content of 0 to 15% by weight, with the proviso that the combination of the high molecular weight butadiene/acrylonitrile copolymer and the low molecular weight butadiene polymer contains at least 2% by weight of carboxyl groups;
• (c) 2 to 40% by weight of a nongaseous, ethylenically unsaturated compound containing at least one terminal ethylenic group, said compound being capable of forming a high polymer by free-radical initiated, chain-propagating addition polymerization and being compatible with polymers (a) and (b);
• and
• (d) 0.001 to 10% by weight of an organic, radiation-sensitive, free-radical generating system, activatable by actinic radiation which initiates polymerization of the unsaturated compound.