| 摘要 |
Use for protective coatings of compositions comprising (% by wt.): A) from 10 to 60% of a A1) (per)fluoropolyethereal prepolymer having a polyisocyanic functionality obtainable by reacting a bifunctional having hydroxylic functionality, said fluoropolyethers having -CH2OH terminations directly linked to a perfluoroalkylic group CF2 or CF2CFX (X = Cl, F) or CF(CF3), with a polyisocyanate containing isocyanurate rings, preferably obtained by cyclotrimerization of HDI, IPDI or other monomeric diisocyanates, by utilizing an excess of isocyanate groups comprised between 10 and 80% by moles; the above fluoropolyether prepolymer can be partially or totally replaced by A2) non fluorinated polyisocyanates containing isocyanurate rings and/or hydrogenated polyisocyanate prepolymers; B) from 0.1 to 50% of a (per)fluoropolyether having bifunctional hydroxylic functionality of the type -CF2CH2OH, -CF2CFXCH2OH (X = Cl, F) or -CF(CF3)CH2OH; or polyfunctional hydroxylic functionality termination but containing at least 5% by weight, preferably 10%, of the same type of termination indicated above for the bifunctional; or (per)fluoropolyethers prepolymers as defined in A) but having a lower prepolymerization degree so to leave free oxydrilyic functions of the type -CF2CH2OH, -CF2CFXCH2OH (X = Cl, F), or -CF(CF3)CH2OH; or the latter prepolymers having free hydroxilic functions can be used alone as a single component, being component A) 0%; C) 10-90%, with respect to the resin of a diluting solvent.
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