# US 6,723,812 B2 · Process for the high-pressure polymerization of 1, 1-difluoroethylene > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,723,812 B2 - Document ID: US6723812B2 - Status: Granted - Kind: B2 - Application number: 09/963,892 - Filed: 2001-09-26 - Published: 2002-09-05 - Granted: 2004-04-20 - Earliest claimed: 2000-09-26 - Assignees: Atofina - Inventors: Thierry Senninger - Web page: https://patentgrep.com/patent/US6723812B2 ## CPC - C08F 14/22: Vinylidene fluoride - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## 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. ## Claims ### Claim 1 A continuous process for the manufacture of PVDF homopolymer or copolymer, wherein a comonomer comprises 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: (a) introducing a flow of VF2, optionally the comonomer, and a radical initiator into a reactor maintained at a pressure of 300 bar-3000 bar, the reactor comprising at least 90% by weight VF2, optionally the comonomer, and PVDF; (b) removing at least a portion of the reaction mixture from (a) and introducing into a separator; (c) recovering molten PVDF in the separator and purging continuously; (c1) optionally introducing the flow of PVDF from (c) into a device to make granules; and (d) recovering VF2 and optionally the comonomer in the separator and recycling into (a). ### Claim 2 (depends on 1) A process according to claim 1, wherein the proportion of comonomer is 0-50% by weight. ### Claim 3 (depends on 1) A process according to claim 1, wherein the pressure is 1500 bar-2500 bar. ### Claim 4 (depends on 1) A process according to claim 1, wherein the radical initiator is tert-butyl perpivalate. ### Claim 5 (depends on 1) A process according to claim 1, wherein the flow rate of initiator is, by weight, 2 ppm-100 ppm of all of the fresh VF2 or of the fresh VF2 and the fresh comonomer combined. ### Claim 6 (depends on 1) A process according to claim 1, wherein the temperature of the reactor is 50° C.-300° C. ### Claim 7 (depends on 1) A process according to claim 1, wherein the temperature is 90° C.-220° C. ### Claim 8 (depends on 1) A process according to claim 1, wherein a product to promote flow is added to the reactor or at the reactor outlet in an amount of 0-10% by weight relative to the mass of fluoro comonomers and PVDF contained in the reactor. ### Claim 9 (depends on 1) A process according to claim 1, further comprising deoxygenating fresh VF2 and optionally the comonomer before introduction into said reactor, the deoxygenating comprising placing the flow of VF2 and of the optional comonomer 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 time which is sufficient to obtain the desired oxygen content. ### Claim 10 A continuous process for the manufacture of PVDF homopolymer or copolymer, said process comprising: introducing a flow of VF2, optionally a comonomer 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, and a radical initiator into a reactor maintained at a pressure of 300 bar-3000 bar, the reactor consisting essentially of VF2, optionally the comonomer, and PVDF; removing at least a portion of the reaction mixture form (a) and introducing into a separator; recovering molten PVDF in the separator and purging continuously; optionally introducing the flow of PVDF from (c) into a device to make granules; recovering VF2 and optionally the comonomer in the separator and recycling into (a); and deoxygenating fresh VF2 and optionally the comonomer before introduction into said reactor, the deoxygenating comprising placing the flow of VF2 and of the optional comonomer 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 and (ii) for a time sufficient to obtain the desired oxygen content. ### Claim 11 A continuous process for the manufacture of PVDF homopolymer or copolymer, comprising introducing a flow of VF2, and optionally a comonomer, into a reactor wherein the reactor contains at least 90% by weight VF2. ### Claim 12 (depends on 1) A process according to claim 1, wherein the reactor comprises no water. ### Claim 13 (depends on 1) A process according to claim 1, wherein the reactor comprises no organic solvent, water or ScCO2. ### Claim 14 (depends on 1) A process according to claim 1, wherein the flow comprises VF2 and the comonomer. ### Claim 15 (depends on 1) A process according to claim 1, wherein the proportion of comonomer is 0-30% by weight. ### Claim 16 (depends on 14) A process according to claim 14, wherein the comonomer is: vinyl fluoride; trifluoroethylene; chlorotrifluoroethylene; 1,2-difluoroethylene; tetrafluoroethylene, hexafluoropropylene; a perfluoro(alkyl vinyl); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole; a product of a formula CF2═CFOCF2CF(CF3)OCF2CF2X where X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a product of a formula CF2═CFOCF2CF2SO2F; a product of a formula F(CF2)nCH2OCF═CF2 where n is 1, 2, 3, 4 or 5; a product of a formula R1CH2OCF═CF2 where R1 is hydrogen of F(CF2)z and z is 1, 2, 3, or 4; a product of a formula R3OCF═CH2 in which R3 is F(CF2)z and z is 1, 2, 3, or 4; perfluorobutylethylene; 3,3,3-trifluoropropene; 2-trifluoromethyl-3,3,3-trifluoro-1-propene; or a combination thereof. ### Claim 17 (depends on 1) A process according to claim 1, wherein the residence time is 1-60 minutes. ### Claim 18 (depends on 1) A process according to claim 1, wherein the radical initiator is: tert-butyl perpivalate, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 1,3-bis(t-butylperoxy-isopropyl)benzene, acetyl peroxide, benzoyl peroxide, isobutyryl peroxide, bis(3,5,5-trimethyl)hexanoyl peroxide, methyl ethyl ketone peroxide, heptane or isododecane. ### Claim 19 (depends on 1) A process according to claim 1, wherein the flow rate of initiator is, by weight, 2 ppm-1000 ppm of all of the fresh VF2 or of the fresh VF2 and the fresh comonomer combined.