Holz als Roh- und Werkstoff

, Volume 62, Issue 6, pp 439–444 | Cite as

The effect of urea-formaldehyde resin pre-cure on the internal bond of medium density fiberboard

  • Cheng Xing
  • Bernard Riedl
  • Alain Cloutier
  • Guangbo He
ORIGINALARBEITEN · ORIGINALS
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Abstract

The effect of elapsed time between resin blending and hot pressing stage on the degree of resin pre-cure is not known in the manufacture of medium density fiberboard (MDF). This phenomenon of resin pre-cure is a clear factor that should be taken into account in MDF manufacture. An experiment which used differential scanning calorimetry (DSC) to quantify resin pre-cure degree after resin blending, and the relationship between resin pre-cure degree and the internal bond strength (IB) of MDF has been conducted. The results indicated that the rate of pre-cure process after resin blending at room temperature (23°C) under constant humidity and temperature conditions included three stages. In the first stage, the rate of pre-cure reaction was close to that of at the third stage, but lower than that of the second stage. The decrease of corresponding IB strength for boards made with material having undergone such pre-cure was very sharp during the first 24 h. After 24 h, the IB decrease displayed a linear relationship with time. The IB displayed a linear relationship with the resin pre-cure degree, as evaluated by DSC.

Keywords

Differential Scanning Calorimetry Internal Bond Medium Density Fiberboard Urea Formaldehyde Resin Internal Bond Strength 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Einfluss des Vorhärtens von UF-Harzen auf die Querzugfestigkeit von MDF

Zusammenfassung

Der Einfluss der Verweildauer zwischen Harzmischung und Heißpressen auf den Grad des Vorhärtens beim Herstellen von MDF ist nicht bekannt. Das Phänomen des Vorhärtens ist ein deutlicher Faktor, der bei der MDF-Herstellung berücksichtigt werden sollte. Es wurden Versuche durchgeführt, die mit Hilfe der Differential-Kalorimetrie (DSC) den Grad des Vorhärtens nach dem Harzmischen und dessen Einfluss auf die Querzugfestigkeit (IB) quantifizieren. Die Ergebnisse zeigen, dass die Reaktion des Vorhärtens bei konstanter Feuchtigkeit drei Stufen durchläuft. In der ersten Phase ist die Aushärtungsgeschwindigkeit gleich hoch wie bei der dritten, jedoch geringer als in der zweiten Phase. Der Abfall der Querzugfestigkeit von Platten nach solchem Vorhärten war sehr steil während der ersten 24 h. Nach 24 h verläuft dieser Abfall linear mit der Zeit, wie aus den DSC-Untersuchungen hervorgeht.

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Notes

Acknowledgements

The authors greatly appreciate Forintek Canada Corp., Québec for supplying materials. C. Xing thanks Natural Sciences and Engineering Research Council (NSERC) and Laval University for financial support for this study.

References

  1. Bucking G (1982) Resin blending of MDF fiber. In: Proceedings of the 16th Particleboard/Composite Materials Symposium, Washington State University, Pullman, WA, pp 269–276Google Scholar
  2. Dunky M (1998) Urea-formaldehyde (UF) adhesive resins for wood. Int J Adh Adhes 18:95–107CrossRefGoogle Scholar
  3. Gran G (1982) Blowline blending in dry process fiberboard production. In: Proceedings of the 16th Particleboard/Composite Materials Symposium, Washington State University, Pullman, WA, pp 245–259Google Scholar
  4. Loxton C, Hague J (1996) Resin blending in the MDF industry—can it be improved? in: Proceedings of the 3rd Pacific Rim Bio-Based Composite Symposium, Kyoto, Japan, December 2–5, pp 392–400Google Scholar
  5. Park BD, Riedl B (1999) Differential scanning calorimetry of phenol-formaldehyde (PF) adhesives. J Wood Chem Technol 19(3):265–286Google Scholar
  6. Robson D (1991) What happens with blending in the MDF blowline? In: Proceedings of the 25th Particleboard/Composite Materials Symposium, Washington State University, Pullman, WA, pp 167–179Google Scholar
  7. Wang XM (1995) Ph.D. Thesis. Laval University, Quebec CityGoogle Scholar
  8. Waters GD (1990) Medium density fiberboard blow line blending-theories in and around the black box. In: Proceeding of NPA Resin and Blending Seminar. National Particleboard Association, Gaithersburg, pp 56–61Google Scholar
  9. Xing C, Riedl B, Cloutier A, Shaler SM (2004) Characterization of urea-formaldehyde resin penetration into medium density fiberboard fibers. Wood Sci Technol (in press)Google Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Cheng Xing
    • 1
  • Bernard Riedl
    • 2
  • Alain Cloutier
    • 3
  • Guangbo He
    • 4
  1. 1.Forintek Canada Corp.Québec G1P 4R4Canada
  2. 2.Département des Sciences du Bois, Faculté de foresterie et de géomatiqueCERSIM, Université LavalQuébec G1K 7P4Canada
  3. 3.Département des Sciences du Bois, Faculté de foresterie et de géomatiqueUniversité LavalQuébec G1K 7P4Canada
  4. 4.University of TorontoTorontoCanada

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