×

Injection-moldable transparent thermoplastic elastomer

  • US 6,984,688 B2
  • Filed: 05/02/2003
  • Issued: 01/10/2006
  • Est. Priority Date: 05/02/2003
  • Status: Active Grant
First Claim
Patent Images

1. A thermoplastic, injection-moldable and recyclable composition consisting essentially of at least one triblock copolymer selected from the group consisting of(a) a substantially colorless hydrogenated first styrene-conjugated diene-styrene block copolymer (HSBC) derived by hydrogenation of a triblock copolymer selected from the group consisting of high vinyl (styrene-butadiene-styrene) (SBS), high vinyl (styrene-isoprene-styrene) (SIS) and high vinyl (styrene-isoprene/butadiene-styrene) (SI/BS) to yield polystyrene-b-poly(ethylene/butylene)-b-polystyrene (high vinyl SEBS), polystyrene-b-poly(ethylene/propylene-3-methylbutene)-b-polystyrene (SEPS), and “

  • polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and

    (b) a blend of (a) with a second substantially colorless SEEPS present in a minor proportion relative to the first HSBC (a), wherein the second SEEPS is optionally high vinyl and (b) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000;

    a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a polyolefinic modifier providing a continuous phase in the TPE, the polyolefinic modifier being selected from the group consisting of polypropylene homopolymer, and a copolymer of propylene with another lower olefin having from 2 to 6 carbon atoms, the modifier having a melt viscosity in the range from 1 to 150 gm/10 min as measured at 230°

    C. under a load of 2.16 kg in accordance with ASTM D1238;

    a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a substantially colorless plasticizer or softening agent compatible with rubbery phases of the foregoing;

    a minor proportion by weight relative to either (a), or (a) and (b), of an end block modifier which associates with the polystyrene, the end block modifier having a glass transition temperature Tg higher than 60°

    C., a MMAP cloud point<

    30°

    C. and a weight average molecular weight Mw in the range from 2,000 to 50,000; and

    ,at least one additive to enhance useful life of the composition.

View all claims
  • 9 Assignments
Timeline View
Assignment View
    ×
    ×