Heterophasic Propylene Copolymer with Improved Properties for Injection Molding Applications
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Abstract
The present invention concerns a heterophasic propylene copolymer of high melt flow for injection molding, which comprise a propylene polymer matrix and a rubber. The heterophasic propylene copolymers of the present invention are characterized by a high viscosity of the rubber phase and a well-defined ratio of the intrinsic viscosities of the rubber phase and the propylene polymer matrix, thus resulting in improved mechanical properties. The present invention further relates to a process for the production of such heterophasic propylene copolymers, their use and articles produced with them.
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Citations
23 Claims
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1-13. -13. (canceled)
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14. A heterophasic propylene copolymer, comprising:
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a propylene polymer matrix (M) comprising a propylene homopolymer or a random copolymer of propylene and at least one further olefin different from propylene, wherein the further olefin is present in amounts up to 4.0 wt % relative to the total weight of the random copolymer, and a rubber (R) comprising a first olefin, which is different from propylene, and a second olefin, which is different from the first olefin; wherein the heterophasic propylene copolymer has a melt flow index ranging from 45 to 75 dg/min, measured according to ISO 1133, condition L, at 230°
C., 2.16 kg;wherein the rubber has an intrinsic viscosity ranging from 2.4 to 4.5 dl/g, measured in tetralin at 135°
C. following ISO 1628; andwherein the ratio of the intrinsic viscosities, measured in tetralin at 135°
C. following ISO 1628, of the rubber (R) and the propylene polymer matrix (M), η
R/η
M, is at least 3.5. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. A process for producing a heterophasic propylene copolymer, comprising:
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obtaining a propylene polymer matrix (M) by polymerizing propylene to produce a propylene homopolymer or by copolymerizing propylene and at least one further olefin different from propylene to produce a random copolymer of propylene and at least one further olefin different from propylene, wherein the at least one further olefin is present in amounts up to 4.0 wt % relative to the total weight of the random copolymer; subsequently transferring the obtained propylene polymer matrix to a further polymerization reactor; copolymerizing a first olefin, which is different from propylene, and a second olefin, which is different from the first olefin, to produce a rubber (R); and obtaining a heterophasic propylene copolymer; wherein the heterophasic propylene copolymer has a melt flow index ranging from 45 to 75 dg/min, measured according to ISO 1133, condition L, at 230°
C., 2.16 kg;wherein the rubber has an intrinsic viscosity ranging from 2.4 to 4.5 dl/g, measured in tetralin at 135°
C. following ISO 1628; andwherein the ratio of the intrinsic viscosities, measured in tetralin at 135°
C. following ISO 1628, of the rubber (R) and the propylene polymer matrix (M), η
R/η
M, is at least 3.5.
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Specification