Fluorinated polyurethanes containing rubber-like polyoxyperfluoroalkylene blocks and rigid blocks

Claim 2

Polyurethanes comprising rubber-like polyoxyperfluoroalkylene blocks and rigid blocks derived from optionally fluorinated, short-chain aliphatic diols and/or low molecular weight aliphatic and/or aromatic diamines, the number of the rigid blocks being equal to or higher than the number of the rubber-like blocks, said polyurethanes being prepared by using aliphatic, cycloaliphatic and/or aromatic diisocyanates and/or perfluoropolyether diisocyanates.

Claim 3

Polyurethanes according to claim 1, wherein the rubber-like blocks are composed of sequences, having an average molecular weight of from about 1500 to about 15000, of one or more oxyperfluoroalkylene units derived from perfluoropolyether diols belonging to the following classes of compounds: a) HO-(CH₂CH₂O) z -CH₂-CF₂O-(C₂F₄O) m (CF₂O) n -CF₂-CH₂-(OCH₂CH₂) z -OH wherein z independently ranges from 0 to 3 and the ratio m/n is from 0.2 to 2, m and n having values such that the molecular weight is within the range indicated above; b) HO-CH₂CF₂-(C₃F₆O) r (C₂F₄O) s (CFXO) t -CF₂CH₂-OH wherein: X = F or CF₃; r, s, t independently are 0 or integers of from 1 to 100, with the proviso that (r+s) is different from 0 and r, s and t have values such that the molecular weight is within the above range; c) HOCH₂CF₂CH₂-(OCF₂CF₂CH₂) p -OR f O-(CH₂CF₂CF₂O) q CH₂CF₂CH₂OH wherein: R f represents a fluoroaliphatic group containing heteroatoms in the chain, p and q each are integers of from 1 to 100, with the proviso that (p+q) >2 and that R f , p and q are such that the molecular weight is within the above range; d) wherein: R f is a fluoroaliphatic group as defined under c), A and A′ are end groups containing -OH, x is 0 or 1 and a and b each are integers of from 1 to 100, with the proviso that (a+b) >2 and that R f , x, a and b are such that the molecular weight is in the above range.

Claim 4

Polyurethanes according to any one of claims 1 and 2, which are crosslinked and are obtainable by utilizing, for their preparation, polyols and/or amines and/or isocyanates having a functionality of higher than 2.

Claim 5

Polyurethanes according to any one of claims 1 to 3, wherein the rubber-like blocks are composed of sequences, having a molecular weight from about 1500 to about 15000, of one or more oxyperfluoroalkylene units derived from perfluoropolyether diisocyanates or belonging to the perfluoropolyether classes indicated in claim 2.