On the structure and cure acceleration of phenol-urea-formaldehyde resins with different catalysts

Abstract Phenol–urea–formaldehyde (PUF) resins with different catalysts [calcium oxide (CaO), sodium carbonate (Na 2 CO 3 ), zinc oxide (ZnO), and magnesium oxide (MgO)] were prepared to accelerate the cure of the resin at low temperature. The cure-acceleration effects of catalysts on chemical structure and cure characteristics of PUF resins were investigated by using both liquid 13 C nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The liquid 13 C NMR analysis indicated that the catalyst such as CaO seemed to present a retarded effect on the polycondensation reaction of phenolic components with urea units, while the Na 2 CO 3 appeared to promote the self-condensation reaction of phenolic methylol groups at para position toward the formation of para – para methylene linkage. Both ZnO and MgO in PUF resins promoted self-condensation reaction of para methylol groups and condensation reaction of ortho methylol groups with para methylol groups. The catalysts such as Na 2 CO 3 , ZnO, and MgO can make PUF resins cure at a low temperature. Among these catalysts, the MgO had the most significant accelerating effect on polycondensation and cure reaction of PUF resin.

[1]  S. M. Lee,et al.  Effects of urea and curing catalysts added to the strand board core‐layer binder phenol–formaldehyde resin , 2007 .

[2]  T. Pehk,et al.  Structural changes in urea-formaldehyde resins during storage , 2002, Holz als Roh- und Werkstoff.

[3]  D. A. Fraser,et al.  Preparation of ‘high-ortho’ novolak resins I. Metal ion catalysis and orientation effect† , 2007 .

[4]  Marko Turunen,et al.  Modification of phenol–formaldehyde resol resins by lignin, starch, and urea , 2003 .

[5]  A. Pizzi,et al.  Fast advancement and hardening acceleration of low condensation alkaline phenol‐formaldehyde resins by esters and copolymerized urea. II. Esters during resin reaction and effect of guanidine salts , 2000 .

[6]  P. Grenier,et al.  Phenolic resins: 2. Influence of catalyst type on reaction mechanisms and kinetics , 1996 .

[7]  Jianzhang Li,et al.  Chemical Structure and Curing Behavior of Phenol–Urea–Formaldehyde Cocondensed Resins of High Urea Content , 2009 .

[8]  N. Yan,et al.  13C NMR study on structure, composition and curing behavior of phenol–urea–formaldehyde resole resins , 2004 .

[9]  Qinglin Wu,et al.  Cure kinetics of aqueous phenol–formaldehyde resins used for oriented strandboard manufacturing: Analytical technique , 2006 .

[10]  Moon G. Kim,et al.  Study of the reaction rates and structures of a phenol-formaldehyde resol resin by carbon-13 NMR and gel permeation chromatography , 1990 .

[11]  A. Pizzi.  Phenolic and tannin‐based adhesive resins by reactions of coordinated metal ligands. I. Phenolic chelates , 1979 .

[12]  G. Du,et al.  Synthesis–structure–performance relationship of cocondensed phenol–urea–formaldehyde resins by MALDI-ToF and 13C NMR , 2008 .

[13]  B. Riedl,et al.  Differential scanning calorimetry of phenol–formaldehyde resins cure-accelerated by carbonates , 1999 .

[14]  B. Riedl,et al.  Phenol‐urea‐formaldehyde cocondensed resol resins: Their synthesis, curing kinetics, and network properties , 2003 .

[15]  Jianzhang Li,et al.  13C‐NMR study on the structure of phenol‐urea‐formaldehyde resins prepared by methylolureas and phenol , 2009 .

[16]  A. Pizzi,et al.  Alkaline PF resins linear extension by urea condensation with hydroxybenzylalcohol groups , 1993 .

[17]  A. Pizzi.  Phenolic and tannin-based adhesive resins by reactions of coordinated metal ligands. II. Tannin adhesive preparation, characteristics, and application , 1979 .

[18]  Liu Jianzhang,et al.  Curing Characteristics of Low Molar Ratio Urea-Formaldehyde Resins , 2006 .

[19]  B. Riedl,et al.  13C-NMR study on cure-accelerated phenol–formaldehyde resins with carbonates , 2000 .

[20]  T. Pakkanen,et al.  Phenol-formaldehyde resol resins studied by 13C-NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry , 1997 .

[21]  Antonio Pizzi,et al.  Handbook of adhesive technology , 1994 .

[22]  A. Pizzi,et al.  Fast advancement and hardening acceleration of low‐condensation alkaline PF resins by esters and copolymerized urea , 1999 .

[23]  Norman Joseph Lane Megson,et al.  Phenolic resin chemistry , 1958 .

[24]  C. Hse,et al.  Synthesis of Phenol-Urea-Formaldehyde Cocondehsed Resins from UF-Concentrate and Phenol , 1994 .

[25]  F. Separovic,et al.  NMR structural elucidation of amino resins , 2004 .

[26]  T. Pakkanen,et al.  Effect of alkalinity on the structure of phenol–formaldehyde resol resins , 2001 .

[27]  B. Riedl,et al.  Differential Scanning Calorimetry of Phenol-Formaldehyde (PF) Adhesives , 1999 .

[28]  D. Grunwald,et al.  Preparation of phenol–urea–formaldehyde copolymer adhesives under heterogeneous catalysis , 2006 .

[29]  A. Pizzi,et al.  The Structure of Some Phenol-Formaldehyde Condensates for Wood Adhesives , 1989 .

[30]  Siqun Wang,et al.  On the networking mechanisms of additives‐accelerated phenol–formaldehyde polycondensates , 1997 .

[31]  C. Hse,et al.  Curing Property and Plywood Adhesive Performance of Resol-Type Phenol-Urea-Formaldehyde Cocondensed Resins , 1995 .

[32]  C. Hse,et al.  Phenol-urea-formaldehyde (PUF) co-condensed wood adhesives , 1998 .

[33]  A. Pizzi,et al.  On the chemistry, behavior, and cure acceleration of phenol–formaldehyde resins under very alkaline conditions , 1993 .

[34]  G. Vázquez,et al.  13C-NMR analysis of phenol-urea-formaldehyde prepolymers and phenol-urea-formaldehyde-tannin adhesives , 2004 .