Low N-vinyl lactam content based biomedical devices

Claim 1

As a new article of manufacture a contact lens formed from a hydrophilic polymer formed by polymerizing (a) one or more N-vinyl lactams and/or heterocyclic N-vinyl monomers, said N-vinyl lactams being selected from the group consisting of N-vinyl-2-pyrrolidinone, N-(1-methyl) vinyl pyrrolidinone, N-vinyl-2-piperidone and N-vinyl-2-caprolactam which may be substituted in the lactam ring by one or more lower alkyl groups, said heterocyclic N-vinyl monomers being selected from the group consisting of N-vinyl imidazole, N-vinyl succinimide, N-vinyl diglycolylimide, N-vinyl glutarimide, N-vinyl-3-morpholinone and N-vinyl-5-methyl-3-morpholinone, (b) one or more hydrophilic comonomers selected from the group consisting of hydroxyesters, free acids, amides and amines of acrylates, methacrylates, or itaconates, said hydrophilic monomer(s) being at least 50% of the total monomer of (a) and (b) present and (c) a resonance free di(alkene tertiary amine) cyclic crosslinking agent, said cyclic compound having the formula CH 2 :CG(CH 2 ) x N˜J˜N (CH 2 ) x CG:CH 2 wherein x is 0 or 1, G is hydrogen or methyl and J is the balance of a structure forming cyclic dialkene urea, said agent being present in an amount from 0.01 to 10 weight percent of the total monomers of (a) and (b) present to form a crosslinked 3-dimensional polymeric network, said polymer having an oxygen permeability of at least 8×10 -11 cm 2 cm/sec.cm 2 mmHg) and a tear initiation strength of at least 2 g/mm of thickness.