BLEND OF STYRENIC BLOCK COPOLYMER AND PROPYLENE-α OLEFIN COPOLYMER

• Main Author: CHANG ANDY C
• Format: Patent
• Language: English
• Published: 27.09.2012
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS OF MACROMOLECULAR COMPOUNDS; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition which is excellent in elasticity and flexibility, while at the same time being readily processible using typical polyolefin processing equipment.SOLUTION: The present invention relates to the thermoplastic elastomer composition comprising: a propylene-α olefin copolymer (a) having at least 70 wt.% of units derived from propylene, and 10-25 wt.% of units derived from ethylene or a C4-C10 α olefin, the propylene-α olefin copolymer exhibiting a heat of fusion of less than 37 Joules/gram and a melt flow rate of from 0.1 to 100 gram/10 minutes; and a styrenic block copolymer (b), wherein the weight ratio of the propylene-α olefin copolymer (a) to the styrenic block copolymer (b) is from 3:7 to 7:3. The composition exhibits: a 2% secant tensile modulus of less than 20 MPa; elongation at break of at least 900%; tensile strength of at least 5 MPa; and a relative immediate residual strain of less than 2X, wherein X is the residual strain exhibited by component (b) alone after the initial application of the 400% strain.