Influence of different catalyst systems on the hydrolytic stability of particleboards bonded with unmodified and modified UF-resins

After a storage time of one year, the influence of different catalyst systems on the release of formaldehyde and volatile acids from particleboards bonded with unmodified and modified UF-resins was studied at 30 C (only for formaldehyde), 40 C and 50 C and 100 % relative humidity. The results reveal that modification of UF-resins with a melamine resin and resorcinol significantly increases the hydrolysis resistance of the UF-resin in the boards. Resorcinol, especially at higher temperatures, was even more effective than melamine resin. Measurable differences in the formaldehyde release of particleboards were detected. The amount of hardener had practically no influence on the release of volatile acids from particleboards. Modification of the UF-resin with resorcinol and melamine resin had no effect on the release of acetic acids from the boards. The release of formic acid decreased slightly on modifying the resin with resorcinol and melamine resin. The results indicate that the influe nce of modification and resin type on the hydrolytic resistance of the boards is still apparent even after a storage time of one year.