Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1994-12-12
1997-06-17
Delmendo, Romulo H.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525247, 525270, 525322, 525323, C08F29708
Patent
active
056398220
ABSTRACT:
High-flow propylene/ethylene copolymers which have a melt flow index of from 2 to 200 g/min under a load of 2.16 kg at 230.degree. C. and which may be produced from the gas phase by polymerization in two stages in an agitated fixed bed in the presence of hydrogen acting as chain stoppage regulator and using a Ziegler-Natta catalyst system comprising a titaniferous solid component which contains a magnesium compound on finely divided silicon oxide or on finely divided aluminum oxide or on a finely divided aluminum silicate having the empirical formula SiO.sub.2.aAl.sub.2 O.sub.3, where a stands for a value between 0.001 and 2, and an aluminum component, by means of a procedure comprising
a) a first polymerization stage in which propylene is polymerized under a pressure of from 20 to 40 bar and at a temperature of from 60.degree. to 90.degree. C., the ratio of the partial pressure of the hydrogen to that of the propylene being adjusted to from 1:100 to 10:100, followed by
b) a second polymerization stage, which consists in the polymerization, at a temperature of from 40.degree. to 100.degree. C., of a mixture of propylene and ethylene and the addition thereof, in the form of polymerized units, to the polypropylene produced in the first polymerization stage, the pressure in this second polymerization stage being from 10 to 30 bar and at least 7 bar lower than that used in the first polymerization stage, while the ratio of the partial pressure of the hydrogen to that of the propylene is adjusted to from 2:100 to 12:100 and the ratio of the weight of monomer converted in the first stage to that of monomer converted in the second stage is kept within the range of 1:1 to 20:1.
REFERENCES:
patent: 4454299 (1984-06-01), Schweier et al.
patent: 4455405 (1984-06-01), Jaggard et al.
patent: 4857613 (1989-08-01), Zolk et al.
patent: 4882380 (1989-11-01), Ficker et al.
Hungenberg Klaus-Dieter
Mueller Patrik
Ruempler Klaus Dieter
Schwager Harald
BASF - Aktiengesellschaft
Delmendo Romulo H.
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