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Impregnation suspension system for expandable styrene/maleic anhydride particles

  • US 4,547,527 A
  • Filed: 12/10/1984
  • Issued: 10/15/1985
  • Est. Priority Date: 12/10/1984
  • Status: Expired due to Term
First Claim
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1. A process for preparing expandable particles from non-equimolar copolymers of styrene and a minor amount of maleic anhydride comprising:

  • a. forming an aqueous suspension of particles of a non-equimolar copolymer of styrene and a minor amount of maleic anhydride, said suspension being stabilized by a suitable suspending agent system;

    b. adding to the suspension a mixture of 3 to 12% by weight based on copolymer of a hydrocarbon blowing agent and 3-20% by weight based on water of a water-soluble metal salt;

    c. maintaining said suspension at a temperature of between 80°

    C. and 150°

    C. until said hydrocarbon is incorporated into the copolymer particle; and

    d. separating said particles from said aqueous suspension.

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