Water-soluble urea-formaldehyde condensate - prodn from formaldehyde reacted with recycled aq alkaline urea formaldehyde

摘要

Urea-HCHO addn. products are prepd. continuously by treating gaseous HCHO or HCHO-contg. gases in bottom pt. of one single absorption column with recycled aq. alkaline, constantly urea-replenished, urea-HCHO soln., contg. esp. 70 wt.% urea; followed by washing out non-absorbed HCHO in upper pt. of column, using water, and directly transferring aq. HCHO soln. formed to lower pt. of column. Amt. of water vapour withdrawn in top pt. of column being greater than amt. of water added in order to wash out HCHO. Pref. temp. is kept at 50-85 degrees C in bottom pt. and at 20-50 degrees C in top pt. of column. Urea-HCHO condensation products in aq. alkaline urea-HCHO soln. the total urea HCHO mol. ratio being 1:1.5-1:4 are useful for further processing in prodn. of plastics, foams, lacquer raw materials, textile additives, glues and fertilisers.