| 摘要 |
A process for the in situ blending of polymers comprising continuously contacting, under polymerization conditions, a mixture of ethylene and at least one alpha-olefin having at least 3 carbon atoms with a catalyst in at least two fluidized bed reactors connected in series, said catalyst comprising: (i) a complex consisting essentially of magnesium,titanium, a halogen, and an electron donor; (ii) at least one activator compound for the complex having the formula AlR sec eX min fHg wherein X min is Cl or OR'''; R sec and R''' are saturated aliphatic hydrocarbon radicals having 1 to 14 carbon atoms and are alike or different; f is 0 to 1.5; g is 0 or 1; and e + f + g = 3; and (iii) a hydrocarbyl aluminum cocatalyst, the polymerization conditions being such that ethylene copolymer having a high melt index in the range of about 0.1 to about 1000 grams per 10 minutes is formed in at least one reactor and ethylene copolymer having a low melt index in the range of about 0.001 to about 1.0 gram per 10 minutes is formed in at least one other reactor, each copolymer having a density of about 0.860 to about 0.965 gram per cubic centimeter and a melt flow ratio in the range of about 20 to about 70, and being admixed with active catalyst, with the proviso that: (a) the misture of copolymer of ethylene and active catalyst formed in one reactor in the series is transferred to the immediately succeeding reactor in the series; (b) in the reactor in which the low melt index copolymer is made: (1) the alpha-olefin is present in a ratio of about 0.02 to about 3.5 mole of alpha-olefin per mole of ethylene; and (2) hydrogen is optionally present in a ratio of about 0.001 to about 0.5 mole of hydrogen per mole of combined ethylene and alpha-olefin; (c) in the reactor in which the high melt index copolymer is made: (1) the alpha-olefin is present in a ratio of about 0.02 to about 3.5 mole of alpha-olefin per mole of ethylene; and (2) hydrogen is present in a ratio of about 0.05 to about 3 moles of hydrogen per mole of combined ethylene and alpha-olefin; and (d) additional hydrocarbyl aluminum cocatalyst is introduced into each reactor in the series following the first reactor in an amount sufficient to restore the level of the activity of the catalyst transferred from the preceding reactor in the series to about the initial level of activity in the first reactor. f |
