| 摘要 |
PROBLEM TO BE SOLVED: To provide a continuous process for producing a polyvinylidene fluoride(PVDF) homopolymer or copolymer, wherein the comonomer is chosen from compounds each containing a vinyl group capable of being opened by the action of free radicals in order to polymerize, and which contains, directly attached to this vinyl group, at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group. SOLUTION: This method for the high-pressure polymerization of 1,1- difluoroethylene(VF2) comprises the following steps: (a) a flow of VF2, of optional comonomer and of radical initiator is introduced into a reactor maintained at a pressure of between 300 bar and 3,000 bar; (b) a flow of reaction mixture is removed from the reactor for the step (a) and introduced into a separator; (c) molten PVDF is recovered in the separator and purged continuously; (c1) the flow of PVDF from the step (c) is optionally introduced into a device to place it in the form of granules; and (d) VF2 and the optional comonomer are recovered in the separator and recycled into the step (a); wherein, the respective oxygen contents of the VF2 introduced in the step (a) and the remaining VF2 recycled are <=5 ppm, preferably <=1 ppm, more preferably 0.1-0.8 ppm.
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