Patent ID: 7141537

Claim:
A composition comprising an organic or aqueous liquid having dissolved or dispersed therein a mixture of fluorinated polyethers of the formula: (R f ) n —X w —Z wherein n is 1 or 2, w is 0 or 1, X is a divalent or trivalent organic linking group, Z is a polar group selected from the group consisting of an acid group or salt thereof, an ammonium group, an amine-oxide group and an amphoteric group, and R f represents a perfluorinated polyether group of the formula: CF 3 CF 2 CF 2 —O—[CF(CF 3 )CF 2 O] k —CF(CF 3 )— wherein k is at least 1; said mixture of fluorinated polyethers having a weight average molecular weight between 750 g/mol and 5000 g/mol and the amount of perfluorinated polyether groups in said mixture where k is 2 or less, is not more than 10% by weight of the total amount of perfluorinated polyether groups in said mixture.