GB1073209A - Improvements in or relating to polyureas - Google Patents

Abstract

Ketimines are prepared by condensing methyl isobutyl ketone with (I) triethylene tetramine, (II) N,N-diaminopropyl stearylamine, (III) iminobispropylamine and (IV) methylimino-bispropylamine.ALSO:Polyureas or polyurea/polyurethane are prepared by adding moisture to an anhydrous composition comprising an aliphatic, cycloaliphatic or araliphatic polyisocyanate and a blocked polyamine which is an aldimine or ketimine of an aliphatic polyamine, the blocked polyamine having not more than one active hydrogen atom. Suitable polyisocyanates are polymethylene, alkylene, alkylidene, cycloalkylene and cycloalkylidene diisocyanates, triisocyanates and numerous araliphatic diisocyanates which may contain one or two aromatic rings and optionally, chlorine, methoxy, methyl and cyano radicals and substituents. Particularly suitable polyisocyanates are those derived from polymeric fat acids and having the formula [R]-[(CH2)yNCO]x where y is 0 or 1, x is 2 to 4 and R is the hydrocarbon group of a polymeric fat acid. Aromatic polyisocyanates may be mixed with the above less reactive polyisocyanates. The polyisocyanates may also be in the form of a polyurethate prepolymer which has been prepared by reacting a polyisocyanate with a polyol which may be monomeric or polymeric e.g. organic diols and triols and polyether and polyester polyols. The aldimines and ketimines are suitably prepared by reacting a carbonyl compound having a total of 2 to 6 carbon atoms with an aliphatic polyamine which preferably contains not more than 2 secondary amine groups, e.g. ethylene diamine, diethylene triamine, triethylene tetramine and the corresponding propylene and butylene diamines and N,N-diaminopropyl stearylamine. It is preferred to use a carbonyl compound which boils below or near the boiling point of water or which readily distils with water. The two components of the composition are simply mixed, if desired in the presence of a solvent, and to form a polyurea, moisture is added or the composition is exposed to atmospheric moisture.ALSO:Various substrates may be coated with a composition comprising an aliphatic, cycloaliphatic or araliphatic polyisocyanate and a blocked polyamine which is an aldimine or ketinine of an aliphatic polyamine, the blocked polyamine having not more than one active hydrogen atom, which composition may then be contacted with moisture to provide the substrate with a coating of a polyurea or polyurea / polyurethane. Examples describe the coating of (a) tin and glass with a diisocyanate prepared from dilinoleic acid of tall oil and aketimine prepared from triethylene tetramine and methylisobutyl ketone, (b) tin, steel, wood and glass with a diisocyanate as used in (a) above and a ketimine prepared from diethylene triamine and methyl isobutyl ketone (c) tin, glass and steel with a diisocyanate as used in (a) above and aketimine prepared from iminobispropylamine and methyl isobutyl ketone, (d) tin and glass with a mixture of p-phenylene-bis (ethyl-2-isocyanate) and aketimine from diethylene triamine and methyl isobutyl ketone dissolved in an organic acetate/xylene solvent and (e) glass, black plate steel and cold rolled steel with a mixture of a polyisocyanate prepolymer prepared from hexamethylene diisocyanate and water and a ketimine from ethylene diamine and methyl isobutyl ketone in an ethyl acetate solvent. The above compositions were cured at 50% relative humidity for a period of days to provide the substrates with tough polyurea coatings.