GB479250A - A process for the production of condensation products from formaldehyde and urea - Google Patents

Abstract

A resinous fusible product is obtained by mixing urea with solid, polymeric formaldehyde at ordinary temperature, without the addition of water or other liquid, and maintaining the mixture at a temperature not above 35 DEG C. until the smell of formaldehyde has substantially disappeared. To obtain a hardenable resin, 70--90 parts by weight of formaldehyde per 100 parts of urea may be employed. Condensation may be effected in the presence of catalysts, and urea may be partly replaced by thiourea or other compound reacting with formaldehyde. The products may be worked up alone or with suitable additions into lacquers, coatings, laminated sheets, shaped articles or pressed masses. In examples: (1) urea and paraformaldehyde, are mixed with zinc oxide by grinding in a ball mill and the mixture stored for about 8 days at 30 DEG C.; (2) urea, paraformaldehyde and citric acid are similarly treated; (3) a glycerine-phthalic acid resin is added to the components in (1); (4) urea and paraformaldehyde are finely mixed in a ball mill, stored for 4 days at 25 DEG C., and the mass mixed with wood meal and heated for 2 hours to 75 DEG C. to produce a moulding mixture; (5) urea, formaldehyde and calcium hydroxide are similarly worked up with alpha cellulose pulp; (6) urea, trioxymethylene, a light-coloured phenol resin and tartaric acid are mixed in a ball mill, stored for 3 days at 20 DEG C., and then mixed with lithopone and zinc oxide; the lightcoloured phenol resin is obtained by mixing 100 g. phenol, 120 g. 40 per cent formaldehyde and 4 g. anhydrous sodium carbonate and heating to boiling for 15 minutes, and then neutralizing with phosphoric acid and vaporizing until a hard resin is obtained.