THERMOSETTING URETHANE COATING COMPOSITIONS

摘要

1389547 Polyurethane coating compositions TAKEDA YAKUHIN KOGYO KK 20 Nov 1972 [20 Nov 1971] 53587/72 Headings C3R and C3P A thermosetting urethane coating composition comprises (A) an active H-containing compound of M.W. 400 to 50,000 and (B) a blocked polyisocyanate obtained by reacting (i) a diisocyanatodimethyl cyclohexane with (ii) a polyol of M.W. up to 300 at a NCO/OH ratio not less than 2À6, removing unreacted (i), and blocking the polyisocyanate product. Removal of unreacted (i) may be partial, retention of up to 20% being tolerable. (A) may be a polyether, polyester or acrylic polyol and terminal OH groups of polyester polyols may be partially esterified with castor or coconut oil fatty acids. B (i) may be the 1,3-, 1,2- or 1,4-isomer or a mixture and glycols, triols and tetrol, including hydroxy amines are specified. Numerous blocking agents, solvents and diluents are mentioned. Curing catalysts, pigments, dyes, levelling agents, stabilizers and coalescents may also be present. Coating.-The composition may be sprayed or brushed as a top or under coat to a substrate, e.g. automobiles, buildings, furniture or electrical goods, and cured at 100‹ to 200‹ C. It may also be used as an adhesive or finishing agent for fibrous materials. Modified acrylic polymers.-As indicated above (A) may be an acrylic polyol, i.e. a polymer of an hydroxyalkyl acrylate or methacrylate or copolymer thereof, e.g. with styrene, acrylic or methacrylic acids or esters, dibutyl fumarate, ethylene, propylene, vinyl or vinylidene chloride, butadiene, isoprene or vinyl acetate. In examples copolymers of styrene with (Example 3) n-butyl acrylate and 2- hydroxyethyl methacrylate or (Example 6) methyl methacrylate and 2-hydroxymethylmethacrylate are used.