FIELD: chemistry.
SUBSTANCE: invention relates to methods for producing modified polytetrafluoroethylene. A method for producing modified polytetrafluoroethylene is proposed, which includes copolymerization of tetrafluoroethylene and a monomer having a polar group in dispersion 1 containing a polymer containing links based on a non-fluorinated monomer and an aqueous medium, under such conditions that the amount of used monomer having a polar group is at most 0.150 wt.% with respect to the total amount of tetrafluoroethylene supplied to the polymerization system, wherein the monomer having a polar group is the monomer represented by the formula (3), where the substituents R31 and R32 each independently represent a hydrogen atom or a fluorine atom, the substituent R33 means a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted by a fluorine atom, L3 is a single bond or a divalent linking group, and R34 is a polar -SO3 M or -COOM group, where M is a hydrogen atom, NH4 or an alkali metal atom; and where the non-fluorinated monomer is a monomer represented by formula (1) in which R11 is a hydrogen atom or an alkyl group, L1 is a single bond, -CO-O-*, -O-CO-* or -O -, "*" denotes a bonding position with R12, and the R12 substituent denotes a hydrogen atom, an alkyl group, an alkenyl group or a nitrile group, with the proviso that when L1 is a single bond, the R12 substituent is a nitrile group. An embodiment of the method for producing modified polytetrafluoroethylene, a method for producing modified polytetrafluoroethylene powder, the corresponding modified polytetrafluoroethylene powder and a method for producing a stretched porous material based on modified polytetrafluoroethylene powder are also proposed.
EFFECT: making modified polytetrafluoroethylene, in which the formation of a fluorinated oligomer containing hydrophilic functional groups as a by-product is negligible, which increases the environmental friendliness of the claimed method and improves the performance of the resulting product.
11 cl, 1 tbl, 10 ex
