Water absorptive composition

A composition capable of absorbing more than 45% of its weight of water without dissolution at room temperature to form an optically clear hydrogel consisting essentially of an optically clear blend of (1) 40 to 98% by weight, based on the total weight of the blend, of a water-soluble polymer of N-vinyl-2-pyrrolidone, having a molecular weight from 10,000 to 1,000,000 and (2) 2 to 60% by weight of a water-insoluble copolymer consisting essentially of 88 to 90% by weight, based on the total weight of the copolymer, of methyl methacrylate and 10 to 12% by weight of 2-acrylamido-2-methyl propanesulfonic acid.

A composition capable of absorbing more than 45% of its weight of water without dissolution at room temperature to form an optically clear hydrogel consisting essentially of an optically clear blend of (1) 40 to 98% by weight, based on the total weight of the blend, of a water-soluble polymer of a vinyl lactam having the structure ##STR7## in which X represents an alkylene bridge having three to five carbon atoms, or a water-soluble copolymer thereof with 1 to 90 mole percent of copolymerizable monomer containing a polymerizable ethylenic unsaturation, said polymer or copolymer having a molecular weight from 10,000 to 1,000,000 and (2) 2 to 60% by weight of a water-insoluble copolymer consisting essentially of 50 to 90% by weight, based on the total weight of the copolymer, of a hydrophobic water-insoluble ethylenically unsaturated monomer, 2 to 12% by weight of an ethylenically unsaturated monomer containing an acid group, and from 15 to 45% by weight of a hydrophilic ethylenically unsaturated monomer free from acidic groups.

A composition capable of absorbing more than 45% of its weight of water without dissolution at room temperature to form an optically clear hydrogel consisting essentially of an optically clear blend of (1) 40 to 98% by weight, based on the total weight of the blend, of a water-soluble polymer of a vinyl lactam having the structure ##STR8## in which X represents an alkylene bridge having three to five carbon atoms, or a water-soluble copolymer thereof with 1 to 90 mole percent of copolymerizable monomer containing a polymerizable ethylenic unsaturation, said polymer or copolymer having a molecular weight from 10,000 to 1,000,000 and (2) 2 to 60% by weight of a water-soluble copolymer consisting essentially of 88 to 90% by weight, based on the total weight of the copolymer, of methyl methacrylate and 10 to 12% by weight of 2-acrylamido-2-methyl propanesulfonic acid.