US 6,071,564 AGranted

Coatings based on perfluoropolyethers

AssigneeAusimont S.p.A.

InventorsRoberta Marchetti, Massimo Malavasi

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Abstract

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 --CH.sub.2 OH terminations directly linked to a perfluoroalkylic group CF.sub.2 or CF.sub.2 CFX (X.dbd.Cl, F) or CF(CF.sub.3), 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 --CF.sub.2 CH.sub.2 OH, --CF.sub.2 CFXCH.sub.2 OH (X.dbd.Cl, F) or --CF(CF.sub.3)CH.sub.2 OH; 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 --CF.sub.2 CH.sub.2 OH, --CF.sub.2 CFXCH.sub.2 OH (X.dbd.Cl, F), or --CF(CF.sub.3)CH.sub.2 OH; 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.

A method for coating and protecting materials, substrates and coatings, comprising applying thereto compositions comprising (% by weight):

A) from 10 to 60% of a A1) (per)fluoropolyethereal prepolymer having a polyisocyanic functionality obtained by reacting a bifunctional, optionally polyfunctional (per)fluoropolyether, having hydroxylic functionality, optionally in admixture with monofunctional (per)fluoropolyethers, said fluoropolyethers having --CH.sub.2 OH terminations directly linked to a perfluoroalkylic group CF.sub.2 or CF.sub.2 CFX (X.dbd.Cl, F) or CF(CF.sub.3), optionally through a bridging linking group (CH.sub.2 CH.sub.2).sub.co' wherein .sub.co is an integer between 0 and 6, with a polyisocyanate:
containing isocyanurate rings, obtained by cyclotrimerization of HDI, IPDI or other monomeric diisocyanates, by utilizing an excess of isocyanate groups comprised between 10 and 80%,
the above fluoropolyether prepolymer can be partially or totally replaced by A2) non fluorinated polyisocyanates containing isocyanurate rings and/or hydrogenated polyisoyanate prepolymers;
B) from 0.1 to 50% of a (per)fluoropolyether having bifunctional hydroxylic functionality of the type --CF.sub.2 CH.sub.2 OH, --CF.sub.2 CFXCH.sub.2 OH (X.dbd.Cl, F) or --CF(CF.sub.3)CH.sub.2 OH, or polyfunctional hydroxylic functionality termination but containing at least 5% by weight, of the same type of termination indicated above for the bifunctional in admixture with mono or polyfunctional perfluoropolyethers having an hydroxylic termination, optionally in admixture with diols and/or hydrogenated polyols having a low molecular weight, or (per)fluoropolyethers prepolymers as defined in A) but having a lower prepolymerization degree so as to leave free hydroxylic functions of the type --CF.sub.2 CH.sub.2 OH --CF.sub.2 CFXCH.sub.2 OH (X.dbd.Cl, F), or --CF(CF.sub.3)CH.sub.2 OH;
or the latter prepolymers having free hydroxylic 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, preferably, belonging to the classes:
ketone, esters, heteroalcohols esters, aromatic, and cycloaliphatic and ailphatic hydrocarbons.

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Abstract

Claims31