Investigation of combination catalyst system for UF resin in particleboard and MDF manufacturing. Part I. Preliminary evaluation of eleven catalyst systems for curing rate, stability and free formaldehyde emission
Ammonium chloride has been commonly used as catalyst for urea-formaldehyde (UF) resin in particleboard manufacturing in North America. To explore a suitable catalyst system as a substitute for ammonium chloride, 11 single and combination catalyst systems were evaluated by measuring the curing rate of UF resin with a differential scanning calorimetry (DSC) analysis in terms of DSC peak temperature, stability at room and elevated temperatures in terms of pH value, and free formaldehyde emission of cured resin. The catalyst systems investigated in the study included (1) A-1 (ammonium chloride), (2) A-2 ammonium sulfate, (3) A-3 (ammonium persulfate), (4) B-1 (ammonium sulfate + ammonium persulfate), (5) B-2 (ammonium sulfate + aluminum chloride), (6) B-3 (ammonium persulfate + aluminum chloride), (7) B-4 (ammonium sulfate + phosphoric acid), (8) B-5 (ammonium chloride + phosphoric acid), (9) C-1 (ammonium sulfate + aluminum chloride + triethanolamine), (10) C-2 (ammonium sulfate + phosphoric acid + triethanolamine), and (11) C-3 (ammonium chloride + triethanolamine + phosphoric acid). Overall better performance was observed for catalyst systems C-2, C-1, B-3, B-2, and A-2. These five catalyst systems were performed similarly to or even better than control A-1, and may be potential catalysts for particleboard manufacturing.