SYNTHESIS OF PHENOL-UREA-FORMALDEHYDE COCONDENSED RESINS FROM UF-CONCRETE AND PHENOL

A new synthetic method to obtain phenol-urea-formaldehyde cocondensed resins was developed by reacting phenol with ''UF-concentrate'', which is a kind of urea-formaldehyde (UF) resin prepared with a high molar ratio of formaldehyde to urea (F/U) such as above 2.5. The products we re analyzed with C-13-NMR spectroscopy and gel permeation chromatograp hy. The ratio of cocondensation and the amount of phenol incorporated into cocondensed resins were found to increase, when the UF-concentrat es were prepared under alkaline conditions. It was also found that res ol-type cocondensed resins can be synthesized by alkaline treatments o f the cocondensed resins which were once prepared under acidic conditi ons.