Abstract The present invention relates to a process for producing a polypropylene-ethylene block copolymer by a continuous multi-stage polymerization comprising a first stage in which polypropylene is polymerized in a first polymerization vessel in the presence of a propylene polymerization catalyst, and a second stage in which propylene and ethylene are copolymerized in a second polymerization vessel, wherein the polypropylene slurry discharged from the first polymerization vessel is supplied to a concentrator to separate said slurry into a concentrated polypropylene slurry and a supernatant liquid, the concentrated polypropylene slurry is then introduced through an upper part of a hydraulic sedimentation classifier to be contacted with a countercurrent of the upward flowing of the supernatant fluid introduced through a lower part of said classifier to obtain hydraulically sedimented polypropylene, and non-hydraulically sedimented polypropylene; the thus obtained hydraulically-sedimented polypropylene is then supplied to the second polymerization vessel or to a further propylene polymerization vessel and the non-hydraulically sedimented polypropylene is then recycled from the classifier to the first polymerization vessel. The present process produces a propylene-ethylene block copolymer having excellent characteristics of cold shortness and high impact strength.
In a process for producing a propylene-ethylene block copolymer by a continuous multi-stage polymerization comprising a first stage in which propylene is polymerized in a first polymerization vessel in the presence of a propylene polymerization catalyst, and a second stage in which propylene and ethylene are copolymerized in a second polymerization vessel, wherein: the polypropylene slurry discharged from the first polymerization vessel is supplied to a concentrator to separate said slurry into a concentrated polypropylene slurry and a supernatant liquid; the concentrated polypropylene slurry is then introduced through an upper part of a hydraulic sedimentation classifier to be countercurrently contacted with the upward flowing supernatant fluid introduced through a lower part of said classifier to obtain hydraulically sedimented polypropylene and not hydraulically sedimented polypropylene; the thus obtained hydraulically-sedimented polypropylene is then supplied to the second polymerization vessel or to a further propylene polymerization vessel; and the not hydraulically sedimented polypropylene is then recycled from the classifier to the first polymerization vessel.
Claim 2
Dependent Claim
161 words
In a process for producing a propylene-ethylene block copolymer by a continuous multi-stage polymerization comprising a first stage in which propylene is polymerized in a first polymerization vessel in the presence of a propylene polymerization catalyst, and a second stage in which propylene and ethylene are copolymerized in a second polymerization vessel, wherein: the polypropylene slurry discharged from the first polymerization vessel is supplied to a concentrator to separate said slurry into a concentrated polypropylene slurry and a supernatant liquid; the concentrated polypropylene slurry is then introduced through an upper part of a hydraulic sedimentation classifier to be countercurrently contacted with the upward flowing supernatant fluid introduced through a lower part of said classifier to obtain hydraulically sedimented polypropylene and not hydraulically sedimented polypropylene; the thus obtained hydraulically-sedimented polypropylene is then supplied to the second polymerization vessel or to a further propylene polymerization vessel; and the not hydraulically sedimented polypropylene is then recycled from the classifier to the first polymerization vessel.
Claim 3
Dependent Claim
18 words
The process of producing the block copolymer according to claim 1 wherein said concentrator is a hydraulic cyclone.
Claim 4
Dependent Claim
35 words
The process of producing the block copolymer according to claim 1 wherein said hydraulic sedimentation classifier has a form of cylindrical part and a tapered bottom connected to the lower part of the cylindrical part.
Claim 5
Dependent Claim
21 words
The process for producing the block copolymer according to claim 1 wherein said propylene polymerization is conducted in a single stage.
Claim 6
Dependent Claim
44 words
The process for producing the block copolymer according to claim 1 wherein a ratio of a slurry returned from said classification system to the previous stage to a slurry fed to the subsequent stage is in the range of 30:70 to 99:1 by weight.
Claim 7
Dependent Claim
33 words
The process for producing the block copolymer according to claim 1 wherein a ratio of a concentrated polypropylene slurry to a supernatant liquid is in the range of 50:50 to 99:1 by weight.
Claim 8
Dependent Claim
48 words
The process for producing the block copolymer according to claim 1 wherein a halogenoaluminum compound having the formula AlR.sub.n.sup.2 X.sub.3-n (wherein R 2 represents a C 1-20 hydrocarbon moiety, X represents a halogen atom and n is a number of 1.5≧n≧0) is newly added to said copolymerization stage.