METHOD FOR CONCENTRATING FLUOROPOLYMER AQUEOUS DISPERSION Russian patent published in 2005 - IPC

FIELD: chemistry of polymers, chemical technology.

SUBSTANCE: invention relates to a method for concentrating fluoropolymer an aqueous dispersion by thermal settling. Method involves mixing the parent dispersion with nonionogenic surface-active substance as a stabilizing agent taken among order of oxyethylated alkylphenols, heating a mixture, its keeping without stirring and, if necessary, the following cooling by natural manner. Then the concentrated phase of upper layer is separated and, if necessary, the additional stabilizing agent is added to the concentrated phase and, if necessary, the concentrated phase is diluted up to the content of fluoropolymer 50-55 wt.-%. As a fluoropolymer, method involves using the following substances: polytetrafluoroethylene, polytetrafluoroethylene modified with hexafluoropropylene, perfluoropropylvinyl ester or 2- perfluoropropoxypropylvinyl ester; polyvinylidene fluoride, polyvinylidene fluoride modified with tetrafluoroethylene; copolymer of tetrafluoroethylene with perfluoropropylvinyl ester or with perfluoroethylvinyl ester, copolymer of tetrafluoroethylene with ethylene. As nonionogenic surface-active substance, method involves using neonol AF-9-n representing a mixture of polyethylene glycol esters of monoalkylphenols of the formula: R-C₆H₄O-(CH₂CH₂O)_nH wherein R means alkyl radical C₉H₁₉-isononyl joined to phenol at para-position with respect to hydroxyl group; n means an average number of moles of ethylene oxide joined to one mole of alkylphenols = 9-10. Indicated neonol is added in the amount 7-10% of water mass in the parent dispersion. Mixtures is heated to temperature 40-65°C and kept without stirring up to the complete separation of phases. Mixture is cooled up to temperature 40°C, not above, and separated of the concentrated phase from upper layer is carried out at indicated temperature. Invention allows reducing time for separation of phases.

EFFECT: improved method for concentrating.

6 cl, 1 tbl, 30 ex