Patent ID: 6184290
Filing Date: 2001-02-06
Classification: C08L,C09D,C09J

Abstract:
An extrudable and moldable thermoplastic elastomeric composition comprising (a) from about 50 to about 99 percent by weight, based on the total weight of the composition, of an unsaturated styrene triblock copolymer containing about 10 to 35 weight percent styrene and (b) from about 1 to about 50 percent by weight, based on the total weight of the composition, of a substantially linear ethylene interpolymer characterized as an interpolymer of ethylene with at least one C.sub.3 -C.sub.20 .alpha.-olefin and having a density from about 0.865 to about 0.885 g/cc, wherein the composition is further characterized as having:i. storage moduli throughout the range of -26.degree. C. to 24.degree. C. of less than 3.5.times.10.sup.9 dynes/cm.sup.2,ii. a ratio of storage modulus at -26.degree. C. to storage modulus at 24.degree. C. of less than 3, andiii. storage moduli at -26.degree. C. and 24.degree. C. about 0.4 to about 2.2 times higher than the storage moduli at -26.degree. C. and 24.degree. C., respectively, of the neat styrene block copolymer portion of the composition,and the substantially linear ethylene interpolymer is further characterized as having:iv. a melt flow ratio, I.sub.10 /I.sub.2 from about 6 to about 15,v. a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation:M.sub.w /M.sub.n.ltoreq.(I.sub.10 /I.sub.2)-4.63, andvi. a critical shear rate at onset of surface melt fracture at least 50 percent greater than the critical shear rate at onset of surface melt fracture of a linear ethylene polymer having about the same I.sub.2 and M.sub.w /M.sub.n.