Utilization of spent-tea leaves and tobacco dusts as additives for plywood adhesive

The technical feasibility of using waste tobacco particles (TP) and spent tea leaves (STL) as plywood glue-mix additive for urea-formaldehyde (UF) and phenol-formaldehyde (PF) resin was investigated. TP from stalks and leaf dust were provided by the National Tobacco Administration (NTA) while the STL was obtained from the Universal Robina Corporation (URC). The TP and STL were processed to produce flour like powder with various particle sizes as one of the study variables. Other variables were the various combinations and percentage compositions of TP and STL. Parameters investigated were the effect of replacing the traditional extender (i.e. viscosity and pH), bond strength (BS), formaldehyde emission (FE) and resistance against subterranean and drywood termites (TR). The best UF and PF glue-mixes developed were piloted in the plywood factories of IM-Wood for the UF and Winlex for the PF. Properties of the pilot-produced plywood were tested for their BS, FE, and TR. Economic viability of producing tobacco stalk flour was calculated based on the laboratory and field data gathered including the cost of producing a full-size 1.22 x 2.44m plywood from the cooperating factories. Service testing through the project's construction company cooperator was also conducted and various house components such as cabinets, ceiling and wall partition were made from the pilot-produced plywood. Results showed that the best TP and STL particle size to be used as glue-mix additives for the UF and PF was the passing 200 mesh or 74 mum. Both the UF and PF bonded plywood produced from the laboratory and factory using developed glue-mix formulations with either TP and STL or combination at 4-8% by mass passed the minimum requirements of the PNS ISO standards for the BS and FE. In addition, both the laboratory and pilot-produced plywood attained a certain degree of TR attributed to the presence of nicotine and other alkaloids in the TP. Cost analysis showed that TP production cost was about P16.29/kilo. For UF, the pilot-produced plywood's glue-mix cost per panel for a 3-ply 5mm plywood was P29.03 at double glue line (DGL) spread while the factory formulation glue-mix cost was P35.04 per DGL, which had a difference of P6.03. For PF, the total production price difference for 3-ply 5mm plywood computed for the same quantity of glue-mix for the developed formulations (P437.75/panel) and commercial control formulation (P487.19/panel) was about P49.44/plywood. The lower glue-mix cost and total production cost of 3-ply 5mm plywood both for the UF and PF showed the great potential of using the new additives in lieu of the traditional additives used by the Philippine plywood factories.