| 摘要 |
Low temperature impact resistant polypropylene compositions are produced by subjecting a block copolymer of propylene and a comonomer, said comonomer being ethylene, a 1-olefin having from 4 to 12 carbon atoms or a mixture thereof, the block copolymer, containing 10 to 60% by weight of comonomer, having an intrinsic viscosity of 8 to 40, a melt index of 0.0 to 0.2 at 230 DEG C. and 2 to 8 alternating blocks of polymerized comonomer and polypropylene in the copolymer macromolecule to a temperature of at least 230 DEG C. with mixing until the melt index of said polymer at 230 DEG C. is 0.2 to 25. The treated copolymer may have a notched impact brittleness temperature below -35 DEG C. and a crystalline melting point of at least 150 DEG C. In Example 1, a copolymer with macromolecules PP-PE-PP-PE-PP-PE, wherein PP is polypropylene and PE polyethylene, is produced by reacting propylene and ethylene alternately in an argon atmosphere using 3TiCl3.AlCl3/Et2AlCl as catalyst. The polymer produced is recovered and extruded at 260 DEG to 390 DEG C. yielding a polymer of melt index 0.7 at 230 DEG C. In Examples 2 and 3, block copolymers containing (2) PP-PE-PP and (3) PE-PP-PE-PP-PE macromolecules are produced by modifying the number and order of the additions of ethylene and propylene in Example 1 and subsequently extruded as in Example 1 to yield polymers of melt index, at 230 DEG C., 2.5 and 20, respectively. Reference has been directed by the Comptroller to Specification 970,478. |
