| 摘要 |
Modified urea-formaldehyde resins are made by reacting a major amount of urea and a minor amount of acetoguanamine, benzoguanamine or phenylacetoguanamine, with formaldehyde under weakly alkaline conditions in the presence of ammonia and hexamine. The formaldehyde may be used in the form of formalin, paraformaldehyde or polyoxymethylene. The reaction is preferably effected with a molar ratio of 0.01 to 1.5 moles of guanamine per 3 moles of urea, at a pH of 7.5 to 8.0 and at 75 DEG to 80 DEG C. The resulting condensates can be hardened by known hardening agents, e.g. NH4Cl and Na3PO4. Examples are given in which the modifier is (1,5,6,7,8) benzoguanamine, (2,3) acetoguanamine, and (4) phenylacetoguanamine. Uses.-For moulding, coating, making laminates, as adhesives, or for finishing textiles and paper. |
