| abstract |
Curable (per)fluoropolyether polyurethanes obtained bynreaction in a first step ofn a) (per)fluoropolyether diols having a number average molecularnweight from 2,000 to 5,000; nwith b) diisocyanates of formula OCN-R-NCO (VIA) n wherein R is a hydrogenated and/or fluorinated radical;nin a second step with the compound c) saturated or unsaturated aliphatic hydrogenated diols,n(alkyl)cycloaliphatic, aromatic; oligomers or polymers ofnbutadiene with a number average molecular weight from 500 nto 4,000 having end hydroxyl groups; nprovided that:n when the diisocyanate b) is used and the radical R innformula (VIA) is: -Ph-CH 2 -Ph-, the hydrogenated diols c)nare optional; when the radical R has a meaning different from thatnabove mentioned, at least one of the used hydrogenatedndiols c) is selected from those belonging to the c 2 )-c 6 ) ngroups; nthe sum of the equivalents of the compounds a) and c) beingnequal to the equivalents of the compound b). |