| 摘要 |
A colourless phenol-modified amino condensation resin is made by neutralising an aqueous solution of an aldehyde with a carbonate of Mg, Ca, Si, Ba or Zn, reacting urea with the resulting solution, adding phenol to the aqueous solution of the precondensate thus produced and reacting the mixture to the desired degree of condensation. The preferred molar ratio of (1) urea/phenol is from 1:0.2 to 1:1, (b) urea/aldehyde is from 1:0.9 to 1:1.2. Aldehydes specified are formaldehyde, paraformaldehyde, trioxymethylene, hexamethylenetetramine and acetaldehyde. Urea can be partially replaced by thiourea, dicyandiamide or melamine. Moulding compositions can be made by impregnating fillers, e.g. a -cellulose, wood flour, walnut shell flour, asbestos and cloth cuttings, with aqueous solutions of the resins, and subsequently drying the impregnated fillers. Dyes, pigments, lubricants and hardening agents may also be added. In a typical example (1) formalin, which had been neutralised with MgCO3, was reacted with urea at 90 DEG C, and then with phenol at a pH of 6.6 to 6.8, and the condensation was completed after 1 hour at 80 DEG C. The pH of the resulting solution was adjusted to 6.9 by adding aqueous formic acid and then to 5.4 by adding aqueous ammonium thiocyanate, and used for impregnating a -cellulose. Uses: for making laminated articles; in treating paper; as components of lacquers; coating compositions; and adhesives. |
