Patent ID: 6407185
Filing Date: 2002-06-18
Classification: C08F,C08L

Abstract:
A process for the preparation of a composition containing ethylene polymers comprising a polymer of high melt index and a polymer of low melt index in at least two reactors, wherein the process comprises stages in which(a) ethylene, a catalyst derived from a transition metal selected from the group consisting of at least one element of Groups IIIB, IVB, VB, and VIB of the periodic table and a cocatalyst are introduced into a first reactor, (b) polymerization of the ethylene is carried out in said first reactor, (c) a mixture comprising one of said polymers, the catalyst and the cocatalyst is drawn off from said first reactor, (d) said mixture and another portion of the ethylene rare introduced into a second reactor, which portion of ethylene is polymerized to form a second ethylene polymer, wherein catalyst and cocatalyst are introduced solely into said first reactor, (i) wherein the weight ratio of the one of said polymers to said second ethylene polymer being equal to (30 to 70):(70 to 30), (ii) wherein at least one of either of (1) one of said polymers of (c) or (2) said second ethylene polymer of (d) is characterized by an intrinsic molecular weight distribution defined by an intrinsic Mw/Mn ratio which is less than or equal to 10, wherein Mw of said Mw/Mn ratio is the weight-average molecular mass and wherein Mn of said Mw/Mn ratio is the number average molecular mass, (iii) wherein the polymer of high melt index has a melt index MI2, measured under a load of 2.16 kg at 190Â° C., of 5 to 1000 g/10 min and wherein the polymer of low melt index has a melt index MI5, measured under a load of 5 kg at 190Â° C., of 0.01 to 2 g/10 min, the ratio between these melt indices being from 500 to 50,000, and (iv) wherein said catalyst has a deactivation constant less than or equal to 0.5 hâˆ’1.