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Microporous polymeric foams and microtextured surfaces

  • US 5,969,020 A
  • Filed: 02/06/1998
  • Issued: 10/19/1999
  • Est. Priority Date: 08/13/1993
  • Status: Expired due to Term
First Claim
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1. A foam precursor comprising:

  • a highly uniform continuous matrix including an organic crystalline thermoplastic polymer and a solid crystalline additive composition dispersed uniformly in said matrix, the foam precursor produced by a process comprising the steps of;

    melting the polymer with the additive composition to form an isotropic solution, said additive composition having a melting point above 25°

    C. and having at least one of the following physical characteristics;

    (i) a sublimation temperature between about 25°

    C. and the lower of the degradation, melting or glass transition temperature of the polymer; and

    (ii) extractability by solvents which are not solvents for the polymer; and

    solidifying the isotropic solution such that the additive composition and the polymer separate by essentially simultaneous crystallization to produce a foam precursor containing crystals of the additive composition.

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