Polypropylene copolymer alloys and process for making
AssigneeExxon Chemical Patents Inc.
InventorsGeorge Byron Georgellis, Chia Yung Cheng, William Moa-Tseng Chien
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Abstract
The present invention relates to polypropylene alloys which are especially suited for soft fiber and fabric applications. An embodiment of these alloys comprise an ethylene-propylene random copolymer having an ethylene content of from about 1.0 to 5.0% by weight, in an amount of from about 40 to 90% by weight of the alloy; and an ethylene-propylene bipolymer having an ethylene content of from about 10 to 30% by weight, in an amount of from about 10 to 60% by weight of the alloy. The present invention further relates to a hybrid process for making these alloys.
Claims10
An ethylene-propylene copolymer alloy, said alloy having a substantially single glass transition temperature, an ethylene content of from about 5 to about 8% by weight of the alloy, and a melt flow rate of from about 3 to about 150 g/10 minutes said alloy comprising:
- (a) a ethylene-propylene random copolymer having an ethylene content of from about 0.1 to about 6.0% by weight, said random copolymer having a MFR of from about 0.1 to about 250, present in an amount of from about 40 to about 90% by weight of the alloy;
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- (b) an ethylene-propylene bipolymer present in an amount of from about 10 to about 60% by weight of the alloy, said bipolymer having an ethylene content equal or lower than a critical value to ensure the miscibility of the random and bipolymer copolymers.
A polymer alloy suitable for soft nonwoven fabric applications comprising two distinct, miscible copolymers of propylene with at least one other alpha-olefin.
A butene-ethylene-propylene terpolymer alloy comprising two components, the first component being a polymer selected from the group consisting of ethylene-propylene random copolymers, butene-propylene random copolymers, and butene-ethylene-propylene terpolymer, the second component being a polymer selected from the group consisting of ethylene-propylene random copolymers, butene-propylene random copolymers, and butene-ethylene-propylene terpolymers, wherein said two components are distinct but miscible.
A process for producing a miscible ethylene-propylene copolymer alloy comprising:
- (a) polymerizing a mixture of ethylene and propylene, in the presence of a catalyst system to form a random copolymer having an ethylene content of 1-3% by weight in an amount corresponding to 40-90% by weight of the alloy;
- (b) in the presence of said catalyst containing random copolymer, further polymerizing a mixture of ethylene and propylene, and controlling the ethylene/propylene mole ratio in the reacting medium at or below a critical value to form an ethylene-propylene bipolymer that is miscible with said random copolymer.
Dependencies are inferred from the claim text.