Crosslinkable fluorinated urethane additives for durable exterior coatings
The invention relates to a crosslinkable fluorinated urethane compound having at least one ethylenically unsaturated functional group. Such compounds are useful as coatings additives such that, when the coating is applied to a substrate, the additive compound is allowed to first migrate to the surface and subsequently crosslink to form a durable oil-, dirt-, and water-repellent surface.
1. A crosslinkable compound having at least one ethylenically unsaturated functional group comprising the reaction product of reagents comprising:
(a) at least one isocyanate compound having at least 2 isocyanate groups, or a mixture of said compounds;
(b) at least one perfluoroalkyl mono-alcohol of Formula (I), or a mixture of said fluorinated mono-alcohols;
R f -Q v -OH (I)
wherein
R f is a straight or branched-chain perfluoroalkyl group of 2 to 20 carbon atoms, optionally interrupted by one or more ether oxygens —O—, CH 2 , CFH, or combinations thereof;
Q is a straight chain, branched chain or cyclic structure of alkylene, arylene, aralkylene, sulfonyl, sulfoxy, sulfonamido, carbonamido, carbonyloxy, urethanylene, ureylene, or combinations of such linking groups; and
v is 0 or 1;
(c) at least one isocyanate-reactive compound having one isocyanate-reactive functional group selected from OH, NH 2 , or SH, and having at least one ethylenically unsaturated group;
(d) at least one isocyanate-reactive compound having at least one terminal carboxylic acid and one isocyanate-reactive functional group selected from OH, NH 2 , or SH; and
(e) optionally, at least one additional isocyanate-reactive compound selected from water, alkoxylated diols, or hydroxyl-functional photoinitiator compounds;
provided that if the isocyanate compound (a) has 2 isocyanate groups, then water is present as an additional isocyanate-reactive compound (e).
2. The crosslinkable compound of claim 1 , where R f is a C 1 to C 6 perfluoroalkyl group, v is 1, and Q is a C 1 to C 6 alkylene group.
3. The crosslinkable compound of claim 1 , where the at least one isocyanate-reactive compound (c) is selected from hydroxyalkyl vinyl compounds, straight or branched alcohol containing an alkyl chain of 2 to 30 carbons and having 1 to 15 olefinic units, allylic or methallylic polyether alcohols, aminoalkyl vinyl compounds, acrylic or methacrylic alkyl alcohols, (meth)acrylic polyether alcohols, or (meth)acrylic amines.
4. The crosslinkable compound of claim 1 , where the at least one isocyanate-reactive compound (d) is selected from hydroxyacetic acid, hydroxypropionic acid, or polylactic acid.
5. The crosslinkable compound of claim 1 , where the at least one isocyanate-containing compound is selected from compounds of Formulas (IIa), (IIb), (IIc), (IId), and (IIe):
6. The crosslinkable compound of claim 1 , where compound (e) is present.
7. A process for forming a coating with improved dirt pickup resistance comprising
(i) contacting a coating base selected from a water-dispersed coating, an epoxy polymer coating, an alkyd coating, a Type I urethane coating, or an unsaturated polyester coating; with a crosslinkable compound of claim 1 to form a coating mixture;
(ii) applying the coating mixture to a substrate to form a coating;
(iii) allowing the crosslinkable compound to migrate to the coating surface to form a crosslinkable surface coating, and
(iv) subsequently reacting the ethylenically unsaturated groups of the crosslinkable surface coating together; and
wherein the coating mixture comprises the coating base in an amount of from about 95 to 99.98% and the crosslinkable compound in an amount of from about 0.02 to 5% by weight, based on the total weight of the coating base and the crosslinkable compound.
8. The process of claim 7 , where the substrate is selected from the group consisting of wood, metal, wallboard, masonry, concrete, fiberboard, and paper.