Epoxy based coating resins with good salt spray resistance - prepd. from epoxy resin-hydroxyalkane monocarboxylic acid reaction prod. and carboxylic acid anhydride, and dilutable with water

摘要

Resins which after neutralisation are useful in the prodn. of water-dilutable coating compsns. are made by reacting a cpd. Q- -CH2-CH(OH)-CH2-M n'-CH2-CH(OH)-CH2-Q' (I), in which n' = 3-7, Q = R2-CO.O-, R2 is a hydroxyalkylgp. if n' = 3-5, or R2 = alkyl or hydroxyalkyl gp. if n' 5, M = O-Ph-C(CH3)2-Ph-O- if n' = 3-5, and if n' 5. M has the same meaning provided that =1 gp. M is a -O-CO-(CH2)m-CO-O- gp. in which m = 2-10, and Q' is the same as Q or an OH gp. and having an aliphatic OH content of =260 equiv. 100g, with a sufficient amt. of a component(II) which reacts as a carboxylic anhydride at 100-150 degrees C with hydroxy cpds. to give a prod. (III) with an acid value of 35 mg KOH/g and an aliphatic OH content of =200 equiv/100 g. Prods. are epoxy based coating resins which give improved salt spray resistance on non-phosphated steel cf to prior art epoxy based coating systems.