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Composition for hydrophilic lens blank and method of casting

  • US 4,042,552 A
  • Filed: 11/14/1975
  • Issued: 08/16/1977
  • Est. Priority Date: 09/19/1972
  • Status: Expired due to Term
First Claim
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1. A contact lens composition which can be subjected to cutting and thereafter hydrated in a buffered saline solution to provide a dimensionally-stable contact lens and also suitable for medicament delivery to the eye having from 50 to 65% water after hydration, said composition in dry form consisting essentially of polymerized random graft copolymer containing:

  • 1. from 67.2% to 79.3% hydroxy ethyl methacrylate;

    2. 14.25% to 28% polyvinyl pyrrolidone;

    3. from 0.1% to 4.04% ethylene glycol dimethacrylate;

    4. from 0.1% to 2.5% methacrylic acid;

    5. from about 0.1% up to 5.0% water, and6. from 50 to 100 ppm of hydroquinone stabilizer;

    said composition having been polymerized in two stages;

    the first stage being carried out with a low temperature peroxide initiator effective at 40°

    to 60°

    C after an induction period modified by said hydroquinone stabilizer at 15°

    to 30°

    C for a period of 2.5 to 6 hours;

    said second stage being carried out with a high temperature peroxide initiator effective at 90°

    to 120°

    C;

    each of said low temperature initiator and high temperature initiators being present in concentrations of 0.05% to 0.15%; and

    said two stages of polymerization being carried out for a total period of at least 4 hours or longer.

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