Low density copolymer composition of two ethylene-.alpha.-olefin copolymers
AssigneeSumitomo Chemical Company, Limited
InventorsNobuo Fukushima, Shuji Kitamura, Kiyohiko Nakae, Tadatoshi Ogawa, Kozo Kotani, Hidekazu Hosono
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Abstract
An ethylene-.alpha.-olefin copolymer composition comprising two ethylene-.alpha.-olefin copolymers which are different in density, intrinsic viscosity and the number of short chain branching per 1000 carbon atoms. Extrusion processed materials, injection molded materials and films obtained from said composition are excellent in strength.
Claims23
An ethylene-.alpha.-olefin copolymer composition excellent in transparency and strength and having a density of 0.915 to 0.929 g/cm.sup.3, a melt index of 0.02 to 50 g/10 min. and a melt flow ratio of 35 to 250, which comprises 10 to 70% by weight of an ethylene-.alpha.-olefin copolymer A and 90 to 30% by weight of an ethylene-.alpha.-olefin copolymer B;
- said copolymer A having a higher molecular weight than copolymer B and being a copolymer of ethylene and an .alpha.-olefin of 3 to 18 carbon atoms and having a density of 0.895 to 0.935 g/cm.sup.3, an intrinsic viscosity of 1.2 to 6.0 dl/g, the number of short chain branching per 1000 carbon atoms (hereinafter abbreviated as "S.C.B.") of 7 to 40 and a (weight average molecular weight)/(number average molecular weight) value of 2 to 10;
- said copolymer B being a copolymer of ethylene and an .alpha.-olefin of 3 to 18 carbon atoms and having a density of 0.910 to 0.955 g/cm.sup.3, an intrinsic viscosity of 0.3 to 1.5 dl/g, S.C.B. of 5 to 35 and a (weight average molecular weight)/(number average molecular weight) value of 2 to 10;
- said copolymer A and said copolymer B being selected in order to satisfy a condition that (S.C.B. of said copolymer A)/(S.C.B. of said copolymer B) is 0.6 to 1.7.
A composition of copolymers of ethylene and an .alpha.-olefin of 3 to 18 carbon atoms, having first and second component groups, said first component group having a higher molecular weight than said second component group, having the following properties:
- (1) density of 0.915 to 0.929 g/cm.sup.3,
- (2) intrinsic viscosity [.eta.] of 0.7 to 4.0 dl/g,
- (3) melt index of 0.02 to 50 g/10 min.,
- (4) S.C.B. being 5 to 45,
- (5) [.eta.]/[.eta]sub.l namely g.sub..eta. * being at least 0.8, where [.eta]sub.l is an intrinsic viscosity of a linear polyethylene having the same weight average molecular weight measured by a light scattering method,
- (6) (S.C.B. of the first component group)/(S.C.B. of the second component group) being 0.6 to 0.8 where the two component groups are prepared by consolidating fractions obtained by column fractionation in two portions of lower and higher molecular weight components, said portions being selected so that the weight ratio of the two portions corresponds to the weight ratio of lower and higher molecular weight components calculated from the gel permeation chromotography curve,
- (7) the second components have a density of 0.910 to 0.955 g/cm.sup.3, an intrinsic viscosity of 0.3 to 1.5 dl/g and S.C.B. of 5 to 35,
- (8) the first components have a density of 0.895 to 0.935 g/cm.sup.3, an intrinsic viscosity of 1.2 to 6.0 dl/g and S.C.B. of 7 to 40, and
- (9) the second components are 30 to 90% by weight and the first components are 70 to 10% by weight.
Dependencies are inferred from the claim text.