Multistage copolymerization process

• US 4,740,551 A
• Filed: 06/18/1986
• Issued: 04/26/1988
• Est. Priority Date: 06/18/1986
• Status: Expired due to Term

• Current Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Foster, E. Gordon
• Primary Examiner(s): Briggs, Sr., Wilbert J.
• Application Number:
  US06/875,829
• Time in Patent Office: 678 Days
• Field of Search: 525/52, 525/53, 525/243, 525/323
• US Class Current: 525/52
• CPC Class Codes: B01J 19/242 in series
• CPC Class Codes: B01J 19/2435 Loop-type reactors
• CPC Class Codes: B01J 2219/0013 by condensation of reactants
• CPC Class Codes: B01J 2219/00171 controlling the density
• CPC Class Codes: B01J 3/008 Processes carried out under supercritical conditions
• CPC Class Codes: B01J 8/26 with two or more fluidised beds, e.g. reactor and regeneration installations
• CPC Class Codes: C08F 10/06 Propene
• CPC Class Codes: C08F 2/001 Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer C08F295/00, C08F297/00 take precedence
• CPC Class Codes: C08F 297/083 the monomers being ethylene or propylene

Abstract

The present invention relates to a multistage, continuous process for the preparation of propylene-ethylene impact copolymers comprising the use of a plug flow pipeline reactor for homopolymerizing propylene, a gas-phase fluidized bed reactor for additional propylene homopolymerization, and a gas-phase fluidized bed reactor for propylene/ethylene copolymerization.

Claims

1. A continuous process for the preparation of propylene-ethylene impact copolymers comprising:

(a) homopolymerizing propylene in a plug flow pipeline reactor in the presence of a liquid medium or high density supercritical phase comprising propylene monomer as a major constituent and in the presence of magnesium chloride and titanium-containing catalyst particles, resulting in a homopolymer slurry;

(b) transferring said homopolymer slurry to a gas-phase fluidized bed homopolymer reactor and homopolymerizing additional propylene;

(c) removing a stream of propylene homopolymer particles from said gas-phase fluidized bed homopolymer reactor and transferring the stream to a gas-phase fluidized bed copolymer reactor;

(d) copolymerizing ethylene and propylene in said copolymer reactor, resulting in a propylene-ethylene impact copolymer; and

(e) removing said propylene-ethylene impact copolymer as a product stream from said copolymer reactor.

2. The process of claim 1 wherein a portion of propylene monomer vaporized in the gas-phase fluidized bed homopolymer reactor is removed, condensed and recycled to said pipeline reactor.

3. The process of claim 1 wherein between 50 and 95 weight percent of total propylene homopolymer in said product stream is produced in said pipeline reactor.

4. The process of claim 1 wherein the amount of propylene polymerized in said pipeline reactor is between 5,000 and 20,000 grams per gram catalyst.

5. The process of claim 1 wherein said pipeline reactor has a ratio of length to inside diameter of greater than 500:

1.

6. The process of claim 5 wherein said pipeline reactor has an inside diameter of between 0.5 and 6 inches and a length of between 1,000 and 10,000 feet.

7. The process of claim 1 wherein the ethylene-propylene copolymer portion of said impact copolymer comprises 10 to 20 weight percent of the total impact copolymer composition.