| 摘要 |
A coating composition comprises the reaction product of (a) methylene-bis-(4-cyclohexylisocyanate) or an adduct having free -NCO groups of methylene-bis-(4-cyclohexylisocyanate) with a polyhydroxy organic compound and (b) a polyester having a hydroxyl number of at least 30 and an acid number below 12 and formed from a fatty acid or dimerized fatty acid and a polyol having a molecular weight of from 62-164, the ratio of isocyanate groups to alcoholic hydroxyl groups being 1.5:1 to 1.0:1. The composition may contain a solvent, e.g. ethyl acetate, cyclohexanone xylene, toluene, bis-(ethoxyethyl) ether or ethylene glycol monoethylether acetate, and driers, e.g. lead naphthenate, dimethyl dioctyl tin, dilauryl tin difluoride, di - 2 - ethylhexyltin - bis - (monobutylmaleate), tri-n-butyl tin acetonate or tertiary amines. In Example (1) a polyester derived from castor oil, pentaerythritol and phthalic anhydride in xylene diluted with ethylene glycol monethylether acetate is mixed with an adduct of methylene-bis-(4-cyclohexylisocyanate) and trimethylol propane, and pigmented with TiO2.ALSO:A polyurethane coating composition comprises the reaction product of (a) methylene-bis-(4-cyclohexylisocyanate) or an adduct of methylene-bis-(4-cyclohexylisocyanate) with a polyhydroxy organic compound, and (b) a polyester having a OH number of at least 30 and an acid number below 12 and formed from a fatty acid or dimerized fatty acid and a polyol of molecular weight 62-164, the ratio of NCO groups to alcoholic OH groups being 1,5:1 to 1:1. The composition may be dissolved in an inert organic solvent and may be applied to a substrate by spraying, brushing, dipping or flow coating and may contain a drier, e.g. lead naphthenate, dibutyl tin dilaurate or tertiary amines, and a pigment, e.g. TiO2. In examples the coatings are applied to steel panels and dried in an oven for 1 hour at 100 DEG C. |
