Fluorine-containing polyether and process for preparing the same

A fluorine-containing polyether of the formula:

• Z--X.sub.n --Z' (III)
• wherein X is --CF.sub.2 CF.sub.2 --R.sub.f --O--C.sub.m F.sub.2m --O--R.sub.f 'CF.sub.2 CF.sub.2 -- in which R.sub.f and R.sub.f ' are the same or different and are each a fluorine-containing polyether chain of the formula:
• --(CH.sub.2 CF.sub.2 CF.sub.2 O).sub.a --(CHClCF.sub.2 CF.sub.2 O).sub.b --(CCl.sub.2 CF.sub.2 CF.sub.2 O).sub.c --(CHFCF.sub.2 CF.sub.2 O).sub.d --(CFClCF.sub.2 CF.sub.2 O).sub.e --(CF.sub.2 CF.sub.2 CF.sub.2 O).sub.f --
• wherein a, b, c, d, e and f are each 0 or a positive integer and satisfy the following equations:
• 2.ltoreq.a+b+c+d+e+f.ltoreq.200 and
• 1.ltoreq.a+c+d+f
• and m is a number of from 1 to 6, Z and Z' are the same or different and are each --COF, --COCl, --COOH or --CF.sub.2 CF.sub.2 --R.sub.f --B in which R.sub.f is the same as defined above and B is a fluorine atom of a C.sub.1 -C.sub.5 perfluoroalkyl group, and n is a number of from 0 to 100, provided that when n is 0, both Z and Z' are --CF.sub.2 CF.sub.2 --R.sub.f B or when n is 1, at least one of Z and Z' is --CF.sub.2 CF.sub.2 R.sub.f B.

A process for preparing a fluorine-containing polyether of the formula:

• Z--X.sub.n --Z' (III)
• wherein X is --CF.sub.2 CF.sub.2 --R.sub.f --O--C.sub.m F.sub.2m --O--R.sub.f 'CF.sub.2 CF.sub.2 -- in which R.sub.f and R.sub.f ' are the same or different and are each a fluorine-containing polyether chain of the formula:
• --(CH.sub.2 CF.sub.2 CF.sub.2 O).sub.a --(CHClCF.sub.2 CF.sub.2 O).sub.b --(CCl.sub.2 CF.sub.2 CF.sub.2 O).sub.c --(CHFCF.sub.2 CF.sub.2 O).sub.d --(CFClCF.sub.2 CF.sub.2 O).sub.e --(CF.sub.2 CF.sub.2 CF.sub.2 O).sub.f --
• wherein a, b, c, d, e and f are each 0 or a positive integer and satisfy the following equations:
• 2.ltoreq.a+b+c+d+e+f.ltoreq.200 and
• 1.ltoreq.a+c+d+f
• and m is a number of from 1 to 6, Z and Z' are the same or different and are each --COF, --COCl, --COOH or --CF.sub.2 CF.sub.2 --R.sub.f --B in which R.sub.f is the same as defined above and B is a fluorine atom or a C.sub.1 -C.sub.5 perfluoroalkyl group, and n is a number of from 0 to 100, which comprises polycondensating a fluorine-containing polyether having a functional group at least at one molecular end by irradiation with ultraviolet light.