Fluorinated vinyl ether copolymers having low glass transition temperatures

Claim 1

Substantially amorphous, fluorine-containing perhalogenated copolymer having a glass transition temperature of -15° C. to -100° C. and consisting essentially of the following structural repeat units in the recited molar amounts, with the total of the amounts being 100%: (a) about 50 to about 80% of --CF 2 CX 1 X 2 -- wherein each of X 1 and X 2 is independently selected from F and Cl; (b) 5 to about 50% of ##STR5## wherein R F is C 1-5 perfluoroalkyl; (c) about 3 to about 50% of ##STR6## wherein R F 1 is C 1-12 perfluoroalkyl and n is an integer and is 3 to 30: and (d) 0 to about 10% of ##STR7## wherein R F 2 is C 1-12 perfluoroalkylene or perfluorophenylene, Q is --CO 2 R, --CN, --F, --Cl, --Br or I, R is C 1 -C 4 alkyl, and m is an integer and is 1, 2 or 3; with the proviso that (i) the total molar concentration of (b), (c) and (d) is 20 to 50%; (ii) the concentration of (c) is at least 20 weight %; and (iii) when R F 2 is perfluoroalkylene, Q is --CO 2 R, --CN, --Br or --I.