METHOD OF PREPARING AQEOUS DISPERSION OF PURIFIED POLYTETRAFLUOROETHYLENE Russian patent published in 2010 - IPC C08F6/16 C08F14/26 C08J3/03 C08L27/18 

FIELD: chemistry.

SUBSTANCE: described is a method of preparing an aqueous dispersion of purified polytetrafluoroethylene, which involves passing a crude aqueous dispersion of polytetrafluoroethylene, containing 10-50 wt % fine particles of polytetrafluoroethylene having average diametre of 0.1-0.5 mcm, 0.05-1.0 wt % salt fluorine-containing carboxylic acid of formula (1) with respect to polytetrafluoroethylene, and 2-20 wt % non-ionic surfactant for formula (2) and/or formula (3) with respect to polytetrafluoroethylene, through a column filled with a weakly basic anion-exchange resin, in ascending direction with linear speed of 0.1-2 mm/s with contact time of 0.2-4 hours with reduction of content of the salt of the fluorine-containing carboxylic acid of formula (1): R¹-COOX, where R¹ is a C_5-9 alkyl group having fluorine atoms instead of 90-100% hydrogen atoms (which can contain 1-2 oxygen atoms of an ether), and X is an ammonium ion; formula (2): R²-O-A-H, where R² is a C_8-18 alkyl group, A is a polyoxyalkylene chain consisting of 5-20 oxyethylene groups and 0-2 oxypropylene groups; formula (3): R³-C₆H₄-O-B-H, in which R³ is a C_4-12 alkyl group, and B is a polyoxyalkylene chain consisting of 5-20 oxyethylene groups.

EFFECT: improved method of preparing an aqueous dispersion of purified polytetrafluoroethylene.

8 cl, 9 ex, 1 tbl