GB278698A - Improvements in the manufacture and production of condensation products of urea and formaldehyde - Google Patents

Abstract

278,698. I. G. Farbenindustrie Akt.- Ges. Oct. 8, 1926, [Convention date]. Addition to 258,289. Urea-formaldehyde condensation products.-In the production of urea-formaldehyde condensation products by the process of the parent Specification, materials capable of furnishing acids during the heat treatment required for hardening are added to the condensation products prior to the hardening stage, i.e. either during or after the practically complete removal of the water. Both inorganic and organic materials may be employed, e.g. magnesium chloride and formic esters; formamide may also be used, for its hydrolysis yields ammonium formate, which becomes converted by excess formaldehyde into hexamethylenetetramine and formic acid. The modifi cation is also applicable to the process of Speci fication 288 346. in which urea and formaldehyde are first condensed in an aqueous acid solution of pH between 4 and 6, and the products then concentrated while maintaining pH between 6 and 7. According to the examples, (1) urea is condensed with formaldehyde in the presence of primary sodium phosphate: after the addition ol a mixture of secondary and tertiary sodium phosphate to reduce the pH to 6.6, the solution is partly concentrated in vacuo; formamide is then added and after the concentration has proceeded further, the viscous product is hardened in a mould by prolonged heat treatment: (2) urea and formaldehyde are condensed in the presence or a buffer mixture of sodium acetate and acetic acid: sodium acetate solution is added and the whole concentrated in vacuo; towards the end of the concentration stage, magnesium chloride is added, and the viscous end product then completely hardened by prolonged heat treatment.