Patent ID: 7829649

Claim:
A perfluoropolyether-polyorganosiloxane block copolymer represented by the following formula (1), the block copolymer having a number average molecular weight, reduced to polystyrene, of from 2,000 to 20,000, W2-Q-Rf-Q-(W1-Q-Rf-Q) g -W2 (1) wherein Rf is a perfluoropolyether block, W1 is a polyorganosiloxane block represented by the following general formula (A) or (B) Si n R 2 2n-k (C y H 2y SiR 1 3-a X a ) k O n-1 (A) Si m R 2 2m-2-k (C y H 2y SiR 1 3-a X a ) k O m (B) wherein R 1 is a C 1-4 alkyl group or a phenyl group, R 2 may be the same or different from each other and is a hydrogen atom or a monovalent hydrocarbon group, X is a hydrolyzable group, y is an integer of from 1 to 5, a is 2 or 3, n is an integer of from 4 to 42, m is an integer of from 3 to 50, and k is an integer of from 1 to 5 Q is a C 2-12 divalent connecting group which may contain an oxygen atom and/or nitrogen atom, W2 is an organosiloxane residue having a group represented by the following formula (2) wherein X, R 1 , y, and a are as defined above for the general formulas (A) and (B), and g is an integer of from 1 to 11.