Emulsion polymerization of dipolymers of tetrafluoroethylene and 3,3,3-trifluoropropene

Abstract

An aqueous semi-batch polymerization process is disclosed for the manufacture of dipolymers of tetrafluoroethylene and 3,3,3-trifluoropropene that contain between 45 and 95 mole percent tetrafluoroethylene and between 5 and 55 mole percent 3,3,3-trifluoropropene.

Description

Claims

1. A semi-batch polymerization process for the manufacture of a dipolymer of tetrafluoroethylene and 3,3,3-trifluoropropene, said process comprising: A) charging a reactor with a quantity of an aqueous solution;B) pressurizing said reactor to a pressure between 0.3 and 10.0 MPa with a first gaseous monomer mixture consisting of between 100 and 95 mole percent tetrafluoroethylene and between 0 and 5 mole percent 3,3,3-trifluoropropene to form a reaction mixture;C) polymerizing said reaction mixture in the presence of a free radical initiator to form a polymer dispersion while maintaining said reactor at said pressure and at a temperature between 25° C. and 130° C.; andD) feeding to said reactor a quantity of a second gaseous monomer mixture at a rate so as to maintain said pressure in said reactor, said second gaseous monomer mixture consisting of between 45 and 95 mole percent tetrafluoroethylene and between 5 and 55 mole percent 3,3,3-trifluoropropene to form a dispersed dipolymer of tetrafluoroethylene and 3,3,3-trifluoropropene.

2. The process of claim 1 wherein said aqueous solution comprises a fluorosurfactant.

3. The process of claim 2 wherein said fluorosurfactant is selected from the group consisting of ammonium perfluorooctanoate, perfluorohexylethylsulfonic acid and ammonium 3,3,4,4-tetrahydrotridecafluorooctanoate.

4. The process of claim 1 further comprising feeding a chain transfer agent to the reactor.

5. The process of claim 1 wherein said pressure is maintained between 0.3 and 3 MPa.

6. The process of claim 1 wherein said temperature is maintained between 30° and 90° C.

7. The process of claim 1 wherein said second gaseous monomer mixture consists of 70 to 85 mole percent tetrafluoroethylene and 15 to 30 mole percent 3,3,3-trifluoropropene.