Amorphous copolymers of perfluoro-2,2-dimethyl-1,3-dioxole

Claim 1

An amorphous copolymer of 58-99 mole % of perfluoro-2,2-dimethyl-1,3-dioxole with complementary amounts of more than one comonomer selected from the class consisting of the following compounds: (a) tetrafluoroethylene, (b) chlorotrifluoroethylene, (c) vinylidene fluoride, (d) hexafluoropropylene, (e) trifluoroethylene, (f) perfluoro(alkyl vinyl ethers) of the formula CF 2 =CFOR F , where R F is a normal perfluoroalkyl radical having 1-3 carbon atoms, (g) fluorovinyl ethers of the formula CF 2 =CFOQZ, where Q is a perfluorinated alkylene radical containing 0-4 ether oxygen atoms, wherein the sum of the C and O atoms in Q is 2 to 10; and Z is a group selected from the class consisting of --COOR, --SO 2 F, --CN, --COF, and --OCH 3 , where R is a C 1 -C 4 alkyl, (h) vinyl fluoride, and (i) (perfluoroalkyl)ethylene, R f CH=CH 2 , where R f is a C 1 -C 8 normal perfluoroalkyl radical; the glass transition temperature of the copolymer being at least 140° C.; the maximum mole percentage, M a . . . M i , of each comonomer in the copolymers being as follows: (a) for tetrafluoroethylene, M a =35, (b) for chlorotrifluoroethylene, M b =42, (c) for vinylidene fluoride, M c =20, (d) for hexafluoropropylene, M d =15 (e) for trifluoroethylene, M e =30 (f) for CF 2 =CFOR F , M f =30, (g) for CF 2 =CFOQZ, M g =20, (h) for vinyl fluoride, M h =25, and (i) for R f CH=CH 2 , M i =10; and the amount of each comonomer other than perfluorodimethyl-1,3-dioxole being such that the sum, S, of the ratios of their mole percentages, m a . . . m i , to the maximum percentage of all such comonomers taken together, 42 mole %, is no larger than 1, as shown below: S=m.sub.a /42+m.sub.b /42+. . . +m.sub.i /42≦1.