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Styrenic polymer composition

  • US 5,654,365 A
  • Filed: 07/11/1996
  • Issued: 08/05/1997
  • Est. Priority Date: 07/24/1995
  • Status: Expired due to Fees
First Claim
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1. An impact-modified syndiotactic polystyrene (SPS) admixture containing at least two impact modifiers, the admixture comprising:

  • (a) from 65 to 95 parts of SPS per 100 parts of the admixture;

    (b) from 5 to 35 parts of a blend of at least two impact modifiers, the blend comprising(i) from 10 parts to 90 parts of at least one block copolymer of at least one block of polystyrene and at least one block of hydrogenated polybutadiene;

    (ii) from 90 parts to 10 parts of at least one core/shell polymer prepared in emulsion and having a core of a butadiene homopolymer or co-polymer with up to 25 weight % of at least one styrenic, (meth)acrylonitrile, or (meth)acrylic ester co-monomer, the core being at least 60 weight % of the total of all stages, and having one or two shells, the first shell or second shell being a styrenic homo- or copolymer with up to 25 weight % of a (meth)acrylonitrile or (meth)acrylic ester co-monomer;

    wherein the impact strength of the admixture is greater than the impact strength of a syndiotactic polystyrene admixture modified at the same impact modifier level, but with at least one block copolymer of at least one block of polystyrene and at least one block of hydrogenated polybutadiene as the sole impact modifier, and also greater than the impact strength of syndiotactic polystyrene modified at the same impact modifier level, but with at least one core/shell polymer having a core of a butadiene homopolymer or co-polymer with up to 25 weight % of at least one styrenic, (meth)acrylonitrile, or (meth)acrylic ester co-monomer, the core being at least 70 weight % of the total of all stages, and having one or two shells, the first shell or second shell being a styrenic homo- or copolymer with up to 25 weight % of a (meth)acrylonitrile or (meth)acrylic ester co-monomer as the sole impact modifier.

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