method for preparation of strong gedispergeerde, verknoopte urea - formaldehyde polycondensation products existing solids.

摘要

1296246 Particulate cross-linked ureaformaldehyde condensation products CIBAGEIGY AG 20 Aug 1970 [12 Sept 1969] 40178/70 Addition to 1239143 Heading C3R Particulate cross-linked urea-formaldehyde condensation products are prepared by adding sulphamic acid or a water-soluble ammonium hydrogen sulphate RNH 3 .HSO 4 , wherein R is H or an organic radical, in the absence of any protective colloid, to an aqueous solution of a urea-formaldehyde precondensate in which the formaldehyde : urea molar ratio exceeds 1À2 : 1 when gel formation starts, and comminuting, drying, and deagglomerating the resultant gel. The precondensate is preferably made at pH 6-9 and 40-100‹ C., and the gelation carried out at between room temperature and 100‹ C. with intensive mixing. The urea and formaldehyde may in part be replaced by other aldehyde-reactive compounds and other aldehydes. In the examples sulphamic acid is added to a UF precondensate in various strengths o aqueous solution.