In the production of particleboards and MDF only liquid resins are used. In OSB production in Europe liquid resins are more often used, while rather in North America powder resins are used. The advantages and disadvantages of liquid and powder resins are summarized in Table 16.
A. Combination of Various Adhesives
For the purpose of obtaining special gluing effects and results, combinations of adhesives or resins might be used, for example:
addition of PVAc to UF resins in order to obtain better wetting of the wood surface [24] and a more elastic glue line [338]
UF/MUF + PMDI (as accelerator, crosslinker and/or fortifier) [8,9,192,193] combination of adhesives in particleboard or OSB production: e. g., core layer of PMDI and face layer of MU(P)F resin or PF resin production of an MUF resin by mixing a UF and an MF resin or a UF resin with an MF powder resin.