CONTROLLED DEGRADATION OF POLYPROPYLENE IN EXTRUDER-REACTOR

• US 3,608,001 A
• Filed: 08/26/1969
• Issued: 09/21/1971
• Est. Priority Date: 08/26/1969
• Status: Expired due to Term

• Current Assignee: James P. Keller, John C. Staton, John W. Harrison, Ronald C. Kowalski
• Original Assignee: James P. Keller, John C. Staton, John W. Harrison, Ronald C. Kowalski
• Inventors: Keller, James P., Kowalski, Ronald C., Harrison, John W., Staton, John C.
• Primary Examiner(s): White, Robert F.
• Assistant Examiner(s): Auville, G.
• Application Number:
  US04/853,017
• Time in Patent Office: 756 Days
• Field of Search: 18/2HA 264/176,40
• US Class Current: 264/40.6
• CPC Class Codes: B29B 7/428 Parts or accessories, e.g. casings, feeding or discharging means
• CPC Class Codes: B29B 7/726 Measuring properties of mixture, e.g. temperature or density B29B7/724 takes precedence
• CPC Class Codes: B29B 7/823 Temperature control
• CPC Class Codes: B29B 7/826 Apparatus therefor
• CPC Class Codes: B29B 9/06 in the form of filamentary material, e.g. combined with extrusion
• CPC Class Codes: B29C 2948/922 Viscosity; Melt flow index [MFI]; Molecular weight
• CPC Class Codes: B29C 2948/92314 Particular value claimed
• CPC Class Codes: B29C 2948/92447 Moulded article
• CPC Class Codes: B29C 2948/92485 Start-up, shut-down or parameter setting phase; Emergency shut-down; Material change; Test or laboratory equipment or studies
• CPC Class Codes: B29C 2948/92514 Pressure
• CPC Class Codes: B29C 2948/92695 Viscosity; Melt flow index [MFI]; Molecular weight
• CPC Class Codes: B29C 2948/92704 Temperature
• CPC Class Codes: B29C 2948/92895 Barrel or housing
• CPC Class Codes: B29C 2948/92904 Die; Nozzle zone
• CPC Class Codes: B29C 2948/92961 Auxiliary unit, e.g. for external melt filtering, re-combining or transfer between units
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/92 Measuring, controlling or regulating
• CPC Class Codes: C08F 110/06 Propene
• CPC Class Codes: C08F 2810/10 including a reactive processing step which leads, inter alia, to morphological and/or rheological modifications, e.g. visbreaking
• CPC Class Codes: C08F 8/06 : Oxidation
• CPC Class Codes: C08F 8/50 : Partial depolymerisation

Abstract

A process for producing in a reproducible, predictable and controllable manner a polypropylene having a desired weight average molecular weight and molecular weight distribution by heating the polypropylene in an extruder-reactor, sampling a portion of the polypropylene to measure a parameter of molecular weight and controlling the conditions in the extruder-reactor in response to the measured parameter.

Claims

2. A process for producing a thermoplastic polymer in a reproducible, predictable and controllable manner which comprises:

contacting said polymer having a weight average molecular weight higher than desired with a gas containing at least 7 mol percent oxygen;

heating sAid polymer admixed with oxygen in an extruder-reactor to a metal temperature within the range of 600* F. to 1,000* F.;

cooling said polymer to an extrusion temperature whereby the extrudate may be handled;

expelling said polymer from said extruder-reactor;

sampling a portion of said expelling polymer;

passing said portion of polymer through a rheometer to measure a parameter of molecular weight of said expelled polymer; and

controlling the conditions in said extruder-reactor in response to the measured parameter of molecular weight to obtain polymer having a desired weight average molecular weight.

3. A process according to claim 2 wherein the controlled condition is temperature.

4. A process according to claim 2 wherein the parameter of molecular weight measured in shear stress.

5. A process according to claim 2 wherein the polymer is polypropylene.