Urea-aldehyde polycondensates, preparation thereof and use thereof as surface coating binders
AssigneeBASF SE
InventorsKurt Fischer, Harro Petersen, Hellmuth Kasch, Horst Schmidt
Life of this patent
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Abstract
Urea-aldehyde polycondensates usable as surface coating binders are obtainable by step-wise reaction of (a) urea and/or urea derivatives with acidic CH aldehydes in a molar ratio of urea:aldehyde of 1:2 in the presence of acids and at from 60.degree. to 120.degree. C. with (b) a mixture of 3 moles of formaldehyde per mole or urea and 3 moles of an acidic CH aldehyde per mole of urea at from 60.degree. to 120.degree. C. with subsequent removal of the water of reaction and treatment of the reaction mixture with an alkali metal alcoholate at from 80.degree. to 100.degree. C.
Claims6
A urea-aldehyde polycondensate obtained by
- (a) the cyclocondensation reaction of 1 mole of a urea of the formula (I) ##STR5## where X is oxygen or sulfur, A is C.sub.1 -C.sub.6 -alkylene, and n is from 0 to 3, with 1.9 (n+1) to 2.2 (n+1) moles of an aldehyde of the formula (II) ##STR6## where R.sup.1 and R.sup.2 are each hydrocarbyl of up to 20 carbon atoms, at from 60.degree. to 120.degree. C. in the presence of an acid to form a 2-oxohexahydropyrimidine derivative, and
- (b) the subsequent reaction of the 2-oxohexahydropyrimidine derivative with a mixture of from 2.8 to 3.2 moles of formaldehyde and from 2.8 to 3.2 moles of aldehyde (II), each per mole of urea (I), at from 60.degree. to 120.degree. C.,
- (c) the removal of water, and
- (d) the further reaction of the resin thus obtained with an alkali metal alcoholate at from 80.degree. to 100.degree. C.
Dependencies are inferred from the claim text.