Patent ID: 8039132

Claim:
A compound of the formula (I) A-(CH 2 —Rf—CH 2 O—B—O) n —CH 2 —Rf—CH 2 -A (I) wherein n is an integer of 1 to 4, A is a group of the formula (a) below, and B is a group of the formula (b) below, p being 1 or 2, R being C 1-4 fluoroalkyl, Rf is —CF 2 O(CF 2 CF 2 O) x (CF 2 O) y CF 2 — or —CF 2 CF 2 O(CF 2 CF 2 CF 2 O) z CF 2 CF 2 —, x, y and z being each a real number of 0 to 50