Process for the purification and stabilization of perfluoropolyethers

US4996368A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventor

• Thomas Gries · Solon, US

Key dates

• Filing date: Jan 29, 1990
• Grant date: Feb 26, 1991
• Expiry date: Jan 29, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G65/321
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The invention relates to a process for the stabilization and purification of perfluoropolyethers of the general formulae (I) or (II) ##STR1## in which R=--F or --C.sub.a F.sub.2a+1 PA1 R'=--F or --C.sub.b F.sub.2b+1 PA1 n,m=0,1, . . . or 12, n being identical with or different from m, 1.ltoreq.n+m.ltoreq.15 PA1 a,b=1,2, . . . or 10, a being identical with or different from b ##STR2## in which R"=--C.sub.f F.sub.2f+1 PA1 R"'=--C.sub.g F.sub.2g+1 PA1 X=--F or --CF.sub.3 PA1 c,d,e=integers such that the molecular weight of the perfluoropolyether is between 200 and 2000, where c, d and e may be identical or different and the units [C.sub.3 F.sub.6 O].sub.c, [C.sub.2 F.sub.4 O].sub.d, and [CFXO].sub.e may be randomly distributed along the molecular chain of the perfluoropolyether, or of mixtures of perfluoropolyethers of this type. The process comprises heating the perfluoropolyethers or mixtures thereof to 150.degree.-360.degree. C. in the presence of a catalyst which contains one or more elements from groups IA, IIA, IIIA, IVA or IVB or compounds thereof.