| abstract |
An interpenetrating polymer network (IPN) composition and a process for the manufacture of hydrogel contact lens using the invention material. The polymeric materials are formed by polymerization of: (1) an unsaturated alkyl(meth)acrylate or its derivatives such as 2-hydroxyethyl methacrylate as the principle monomer; (2) optionally vinyl containing comonomer(s) to enhance the resulting hydrogel water absorbing capability; (3) polymerizable multi-functional crosslinking agent(s); (4) an irradiation initiator and/or thermal initiator; (5) optionally other additives to impart the resulting hydrogel specific properties such as ultra-violet blocking ability and handling colors; in the presence of a soluble, hydrophilic IPN agent such as polyvinylpyrrolidone (PVP) or poly-2-ethyl-2-oxazoline (PEOX) with a specific molecular weight range. The novel hydrophilic hydrogel material in the present invention can be used to produce a spherical contact lens, a toric contact lens, a multifocal contact lens, a toric-multifocal contact lens, and other medical devices. The inventive hydrogel material shows a low degree of surface friction, a low dehydration rate, and a high degree of biodeposit resistance. |