GB966338A - Polyurethane surface coatings - Google Patents

Abstract

Polyurethane coatings on surfaces are prepared from a polyester, aliphatic polyether, or polyesteramide by mixing with a polyisocyanate obtained from an aliphatic or cycloaliphatic di-isocyanate by condensation with an aliphatic polyhydric alcohol containing more than two hydroxyl groups per molecule or by polymerization to an isocyanurate, in the presence of a metallic compound containing zinc, cobalt, iron, tin, antimony, titanium, lead, calcium, bismuth, manganese, thorium or zirconium, or of a tertiary amine and applying the mixture to surfaces. Starting materials from which the polyester, polyesteramide or aliphatic polyether may be prepared are listed as are starting materials for the preparation of the urethane or isocyanurate polyisocyanates. (1) In the preparation of the urethane isocyanates a dihydric alcohol may be added to the polyhydric alcohol. Metallic compounds specified are the naphthenates, octoates and acetylacetonates of the aforementioned metals and preferably zinc naphthenate, zinc octoate, calcium naphthenate, calcium octoate, dibutyltin dilaurate or lead 2-ethylhexoate. Tertiary amines specified are triethylamine; pyrollizidine; N, N-dimethylphenylethylamine; N, N-dimethylcyclohexylamine; tetramethylethylenediamine; N-ethylmorpholine and especially 4-dimethylaminopyridine; triethylenediamine and tetramethylguanidine. Optional additives specified, or used in the examples are solvents, e.g. cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, ethyl acetate, butyl acetate, b -ethoxyethyl acetate, toluene and mixtures of such solvents; pigments; fillers; flowing out agents, e.g. cellulose acetobutyrate, ethyl cellulose and urea-formaldehyde resins. Urethane polyisocyanates are prepared in examples from (1) trimethylolpropane, 1,3-butylene glycol and hexamethylene di-isocyanate; (9) trimethylolpropane, butylene glycol and 1-methyl-2,4-di-isocyanatocyclohexane; and (11) trimethylolpropane, butylene glycol and a mixture of di-isocyanates obtained by phosgenating the hydrogenated condensation product of o-toluidine, aniline and formaldehyde. Isocyanurate polyisocyanates are prepared in examples by heating (2) hexamethylene di-isocyanate and (10) 1-methyl-2,4-di-isocyanato-cyclohexane in the presence of lead naphthenate.ALSO:Coatings on surfaces are prepared from a polyester, polyesteramide or aliphatic polyether by mixing with a polyisocyanate obtained from an aliphatic or alicyclic di-isocyanate by condensation with an aliphatic polyhydric alcohol containing more than two hydroxyl groups per molecule or by polymerization to an isocyanurate, in the presence of a metallic compound containing zinc, cobalt, iron, tin, antimony, titanium, lead, calcium, bismuth, manganese, thorium or zirconium, or of a tertiary amine and applying the mixture to the surfaces to be coated. A dihydric alcohol may have been used in addition to the polyhydric alcohol in the preparation of the urethane polyisocyanate. Optional additives which may also be present are solvents, pigments, fillers and flowing out agents such as cellulose derivatives and ureaformaldehyde products. The coatings may be applied by spraying, dipping, or brushing to wood, rubber, metal, fabric, hardboard, asbestos, cement, glass or polyvinyl chloride surfaces. In the examples the coatings are formed on white glazed earthenware tiles. The coating may, but need not necessarily, be stoved.