Thermoplastic elastomer
AssigneeBASF SE
InventorsKonrad Knoll, Hermann Gausepohl, Norbert Niessner, Dietmar Bender, Paul Naegele
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Abstract
An elastomeric block copolymer comprising at least one block A having polymerized units of a vinylaromatic monomer and forming a rigid phase and at least one elastomeric block B/A having polymerized units of both vinylaromatic monomers and of a diene and forming a flexible phase, and glass transition temperature Tg of the block A being above 25.degree. C. and that of the block B/A being below 25.degree. C. and the phase volume ratio of block A to block B/A being chosen so that the amount of the rigid phase in the total block copolymer is 1 to 40% by volume and the amount of the diene is less than 50% by weight.
Claims12
An elastomeric block copolymer of
- i) from 15 to 65% by weight, based on the total block copolymer, of butadiene, and
- ii) from 35 to 85% by weight, based on the total block copolymer, of styrene, which block copolymer consists essentially of
- a) at least two blocks A which have polymerized units of styrene, a glass transition temperature Tg above 25.degree. C. and form a rigid phase, and
- b) at least one elastomeric block which is composed of about 25 to 70% by weight of butadiene and 75 to 30% by weight of styrene, and which has polymerized B/A units of styrene and butadiene in a random structure, a glass transition temperature Tg from -50.degree. C. to +25.degree. C., and is located between two blocks A and forms a flexible phase,
- and the amount of the rigid phase accounts for 5 to 40% by volume.
Dependencies are inferred from the claim text.