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Process for making polyvinyl chloride compositions having high heat distortion temperatures

  • US 5,502,111 A
  • Filed: 04/12/1994
  • Issued: 03/26/1996
  • Est. Priority Date: 03/06/1991
  • Status: Expired due to Term
First Claim
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1. A process for the manufacture of a polyvinyl chloride composition having an improved heat distortion temperature, said process comprising blending at a temperature set within a range of about 150°

  • -220°

    C.(A) 50-95 parts by weight of polyvinyl chloride with(B) a complementary amount, the total adding to 100 parts by weight, of a polymer blend, comprising a matrix and a dispersed phase, consisting essentially of about(i) 30-85 weight percent of a dispersed phase of an imidized acrylic resin having a glass transition temperature above 150°

    C., as determined according to ASTM standard D3418, taking the midpoint value, and a flexural modulus of at least 690 kPa wherein at least 20% of ester groups originally present in the resin are imidized to units of the following formula (1);

    ##STR2## wherein each one of R1, R2, and R3 independently is hydrogen or a C1 -C20 alkyl, cycloalkyl, or aryl group, said imidized acrylic resin further containing 0-50 weight percent of a copolymerized ethylenically tinsaturated additional monomer and being substantially free of functional groups capable causing degradation of polyvinyl chloride within the temperature range of about 150°

    -220°

    C.;

    said resin being melt-processable at a temperature within the range of about 200°

    to 300°

    C.;

    (ii) 15-70 weight percent of a matrix of a third polymer, which is melt processable throughout the temperature range of about 150°

    to 300°

    C. and is substantially free of functional groups capable of causing degradation of imidized acrylic resin within the temperature range of about 200°

    -300°

    C. and of polyvinyl chloride within the temperature range of about 150°

    -220°

    C.;

    said polymer blend (B) of imidized acrylic resin (i) with third polymer (ii) being melt-processable below about 220°

    C.;

    blending of polyvinyl chloride with polymer blend (B) being conducted under such temperature and shear conditions that blend (B) becomes dispersed in polyvinyl chloride; and

    substantially all of the imidized acrylic resin (i) forms compatible, single-phase composition with polyvinyl chloride.

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