Process for the high-pressure polymerization of 1,1-difluoroethylene

Abstract

The invention relates to a continuous process for the manufacture of PVDF homopolymer or copolymer. The optional comonomer comprises a vinyl group polymerized by free radicals, and comprises at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group, directly attached to this vinyl group. The invention also relates to PVDF homopolymers made by processes of the invention. The invention further relates to a process for deoxygenating a flow.

1 . A process for deoxygenating a flow comprising at least one fluoro monomer selected from VF2 and monomers comprising a vinyl group polymerizable by free radicals and at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group, directly attached to this vinyl group, said process comprising placing this flow in contact with (i) a sufficient amount of a catalyst whose active sites are elements belonging to groups 8 to 11 of the Periodic Table of the Elements and (ii) for a period which is sufficient to obtain the desired oxygen content.  
     
     
         2 . A process according to  claim 1 , wherein the support for the active sites is a mineral of alumina, silica, a zeolite or an aluminosilicate.  
     
     
         3 . A process according to  claim 2 , wherein the catalyst comprises 0.05-5% by weight of the active element.  
     
     
         4 . A process according to  claim 1 , wherein the temperature is 0-200° C.  
     
     
         5 . A process according to  claim 1 , wherein the temperature is 50° C.-100° C.  
     
     
         6 . A process according to  claim 1 , wherein the active element is copper or palladium.  
     
     
         7 . A process according to  claim 1 , wherein the flow of deoxygenated VF2 and of optional comonomer comprises less than 5 ppm of oxygen.  
     
     
         8 . A process according to  claim 1 , wherein the oxygen content is less than 1 ppm.  
     
     
         9 . A flow comprising less than 5 ppm of oxygen, and at least one fluoro monomer selected from VF2 and monomers comprising a vinyl group self polymerizable by free radicals, wherein the monomer comprises at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group directly attached to this vinyl group.  
     
     
         10 . A flow according to  claim 9 , comprising less than 1 ppm of oxygen.  
     
     
         11 . A PVDF, optionally comprising from 0 to 50% of comonomers, having a melt flow index, measured at 230° C. under a 5 kg load, of greater than 50 g/10 min according to ASTM D-1238.  
     
     
         12 . A PVDF according to  claim 11 , having a melt flow index, of greater than 100 g/10 min according to ASTM D-1238.  
     
     
         13 . A PVDF according to  claim 11 , having a melt flow index, of greater than 200 g/l 0 min according to ASTM D-1238.  
     
     
         14 . A PVDF according to  claim 11 , having a melt flow index, of greater than 400 g/10 min according to ASTM D-1238.  
     
     
         15 . A PVDF homopolymer with a level of defects, measured by fluorine NMR, of greater than 6%.  
     
     
         16 . A PVDF homopolymer according to  claim 15 , with a level of defects, measured by fluorine NMR, of greater than 7%.  
     
     
         17 . A PVDF homopolymer with an elastic modulus (at 23° C., according to ASTM D-1708) of between 1020 and 650 MPa.  
     
     
         18 . A PVDF homopolymer according to  claim 17 , with an elastic modulus (at 23° C., according to ASTM D-1708) of less than 1000 MPa.  
     
     
         19 . A PVDF homopolymer according to  claim 17 , with an elastic modulus (at 23° C., according to ASTM D-1708) of less than 900 MPa.  
     
     
         20 . A PVDF homopolymer according to  claim 17 , with an elastic modulus (at 23° C., according to ASTM D-1708) of less than 800 MPa.  
     
     
         21 . A PVDF homopolymer according to  claim 17 , with an elastic modulus (at 23° C., according to ASTM D-1708) of less than 700 MPa.  
     
     
         22 . A PVDF with an Mw/Mn ratio of 1.5-1.9.