Producing process for veneer decorative straw particleboards
Technical parameters in different steps of birch (Betula alnoides Buch.-Ham. ex D. Don) veneered decorative straw particleboards producing process including moisture content adjustment, sanding, hot-pressing and conversation to improve the surface warp was discussed in this study. The results showed that it took at least 24 h to adjust the stable moisture content between 8 and 10 % in environment of 30ºC and 40 % relative humidity (RH). Surface warp decreased with the increase of sand thickness till 0.8 mm which indicated the complete remove of hardening layer. Modified “PVAc+GB-3+flour” bonded boards had better surface bonding strength than PVAc with a best hot-pressing parameter: unit pressure 0.7 MPa, temperature 90ºC and hot pressing time 180 s. In addition, surface warp of hot-pressed veneer decorative straw particleboards stabled when conserved for 24 h sealed with plastic films. Enterprise large scale production according to this technical process proved to decrease the surface warp from 1.05±0.3 % (normal process with sanding thickness of 0.3 mm) to 0.84±0.2 %.