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Reaction injection molding as a process to prepare contact lenses

  • US 5,656,210 A
  • Filed: 03/31/1995
  • Issued: 08/12/1997
  • Est. Priority Date: 03/31/1995
  • Status: Expired due to Term
First Claim
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1. A process for the preparation of a reaction injection molded contact lens comprising(a) mixing components in a reactive mixture in a RIM machine under sufficient conditions to form precursors for a polyurea network and a polyacrylic network, which upon curing forms on a interpenetrating polymer network, said reactive mixture comprising:

  • (i) an amine terminated chain extender comprising a mixture of amines A and B, said amines being present in said reactive mixture in about 20-60% by weight, wherein A is ##STR21## wherein f1 is independently an integer from 1-75, R is an alkylene containing 3 carbon atoms and each R is the same,f is an integer between 1 and 150;

    R10, R11, R12, R13 and R14 are independently hydrogen or lower alkyl;

    Z1 and Z2 are independently a chemical bond or lower alkylene,with A and B being present in relative weight ratios ranging from about 60/40 to about 100% A;

    (ii) an organic di-or poly-isocyanate present in sufficient quantity to react with said amine terminated chain extender of (i) to form therefrom a polyurea network;

    (iii) an acrylic ester of the formula;

    ##STR22## wherein R3 is hydrogen or lower alkyl;

    m is an integer from 0 to 150;

    Z3 and Z5 are independently alkylene;

    Z4 and Z6 are independently a chemical bond or alkylene;

    R4 is hydrogen, lower alkyl or ##STR23## R5 is hydrogen or lower alkyl;

    R6 and R8 are independently hydrogen or lower alkyl;

    R7 is lower alkylene, a chemical bond or --CH2 (OCH2 CH2)q --;

    q is an integer between 0 and 200, inclusive;

    p is an integer of 1-3.said acrylic ester being present in said reactive mixture in about 10-50% by weight;

    (iv) a free radical initiator being present in said reactive mixture in sufficient quantity to polymerize the acrylic ester of (iii) forming therefrom a polyacrylic network; and

    (v) a triamine present in sufficient quantity to crosslink said amine terminated chain extender of (i) wherein the ratio of polyurea to polyacrylic ranges from about 90;

    10 to about 50;

    50, and the sum of the weights of the components in the reactive mixture adds to 100%;

    (b) injecting said reactive mixture of (a) into a closed mold in fluid communication with the RIM machine and having a cavity in the shape of a contact lens under conditions sufficient to gel and harden said liquid into an interpenetrating polymer network;

    (c) removing the product of (b) from the mold;

    (d) optionally post-curing the product of (c) and(e) immersing the product of (d) in a water or an aqueous medium to form a hydrogel.

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