Mixtures containing A) reaction products of isocyanates with isocyanate-reactive silanes and B) carbosilane-dendrimers, a process for the preparation of powder coatings from the mixtures and their use

摘要

Compositions comprise: (A) reaction product(s) of isocyanate(s) with NCO-reactive silane(s) of formula Y-R2-Si(R3)n(OR4)3-n (I); and (B) carbosilane dendrimer(s) with condensation crosslinked end groups. In (I), Y = NHR1 or OH; R1 = hydrogen, 1-18C alkyl, 5-8C cycloalkyl, 6-10C aryl or 7-12C aralkyl; R2 = 1-5C alkylene; R3, R4 = 1-18C alkyl or alkoxyalkylene with up to 5 carbon atoms; and n = 0, 1 or 2. Also claimed is a method of preparing powdered blends of the above compositions where the separate components (A), (B) and optionally melted (C), are intensively mixed together as fluid and subsequently cooled. Preferably the isocyanate is a polyisocyanate based on hexa-methylene diisocyanate and/or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane. The NCO-reactive silane is NH2-CH2CH2CH2-Si(OC2H5)3 and/or NH2-CH2CH2CH2-Si(OCH3)3. The carbosilane dendrimers with condensation crosslinked end groups (B) are most preferably compounds of formula (III) which are hydrolysed before or during the addition of component (A). R4-iSi((CH2)nSiXaR3-a)i (III) (sic) n = 2-10; a, b = 1-3; i = 3 or 4; R, R1 = optionally substituted 1-8C alkyl and/or optionally substituted 6-10C aryl group; and X = OR', ((CH2)nSi(OR')bR3-b), ((CH2)nSir3-a((CH2)nSi(OR')bR3-b)a) or ((CH2)nSiR3-a((CH2)nSiR3-a((CH2)nSi(OR')bR3-b/ SB)a). The compositions contain the additives (C) pigments, deaerating agents, flow control agent, light stability agent and/or catalysts. The mass ratio of (A) to (B) is 10:90-90:10.