GB1329910A - Process for preparing thermosettable urethane resin - Google Patents

Abstract

1329910 Thermosettable urethane resins MITSUBISHI CHEMICAL INDUSTRIES Ltd 29 Dec 1971 [29 Dec 1970 (2) 20 April 1971] 60569/71 Heading C3R [Also in Division C7] Thermosettable urethane resins are prepared by reacting a product (I), which is obtained by the reaction of one equivalent of an NCO- terminated polyurethane prepolymer and at least two equivalents of a tertiary amine having on average at least three OH groups per molecule with a product (II) which is obtained by the equimolar addition reaction of an organic diisocyanate and a monofunctional blocking agent, in such proportions that 20 to 80% of the OH groups of (I) are reacted with the NCO groups of (II). A resin which is water emulsifiable or water soluble may be prepared by reaction of the above urethane resins with an acid. The prepolymer may be prepared by reacting an organic diisocyanate with a glycol, polyether or polyester, suitably in a solvent. Suitable tertiary amines containing hydroxyl groups are triethanolamine and propylene oxide addition products of ammonia, ethylene diamine, diethylenetriamine and tris-(3-aminopropyl)- amine. The blocking agent used in the production of product (II) may be a phenol, lactam or tertiary alcohol. On reaction with an acid, e.g. acetic acid, cationic urethane resins are produced which may be used in the form of an aqueous solution or emulsion particularly in electrodeposition coating processes. In a typical example toluene diisocyanate is reacted with polypropylene glycol to form a prepolymer which is then reacted with triethanolamine in acetone to form product (I). Product (II) is formed by reaction of toluene diisocyanate and #-caprolactam and is added to product (I) and reacted. The reaction product is added to an aqueous solution of acetic acid to form a cationic urethane resin which is coated on a glass plate and cured by heating.