METHOD OF CONCENTRATING AQUEOUS DISPERSION OF TETRAFLUOROETHYLENE/HEXAFLUOROPROPYLENE COPOLYMER Russian patent published in 2004 - IPC

FIELD: polymer production.

SUBSTANCE: concentration is effected by thermal settling involving mixing initial dispersion with nonionic surfactant belonging to oxyethylated alkylphenol series, heating resulting mixture, ageing it without agitation, allowing to cool, separating concentrate from upper layer, and, if necessary, diluting it to 50-55 wt %. According to invention, oxyethylated alkylphenol mixture utilized is depicted by general formula R-C₆H₄O-(CH₃CH₂O)_nH, wherein R represents C₈-C₁₂-alkyl and n=7-9, with aqueous solution clarification temperature 56-60^оС, which is added in amount 7-10% on the weight of water in initial dispersion. Before heating, ammonia solution is added to provide pH 9.5-10.5 and heating is then effected to 40-65^оС. Ageing without agitation is continued until dispersion is completely stratified. Cooling is ended when temperature 20-40^оС is attained.

EFFECT: diminished stratification time and simplified concentration technology.

3 cl, 1 tbl, 12 ex