PRODUCTION OF PLYWOOD PANEL FOR EXTERIOR USE WITH PARICÁ AND EMBAÚBA TIMBERS

ABSTRACT This research objective was to evaluate the technical feasibility of using Schizolobium amazonicum Huber ex Ducke (Paricá) and Cecropia palmata Willd (Embaúba) timbers for the production of veneers and external plywood using two types of adhesives: phenol-formaldehyde and tannin-formaldehyde, and different veneer compositions. The trees were harvested in a planted forest area from gap enrichment in the municipality of Dom Eliseu, Pará state. The Pinus elliottii timber was used as the reference and was donated by a company located in the municipality of Irati, Paraná state. The panels were produced with pure timber of the three species, and two combinations between the paricá and embaúba species, using a resin weight of 145 g m 2 in single line. The veneers yield for the paricá was 80.03% and that of the embaúba 46.37%; The panels produced with pure embaúba timber, or in combination with paricá timber, and bonded with phenol-formaldehyde, presented satisfactory technological properties for external use and were the compositions that presented better properties. The best adhesive for the panels was phenol-formaldehyde, as the tannin-formaldehyde did not present good performance in the weight used in this study.摘要：本研究旨在评估采用亚马逊孪叶豆（Schizolobium amazonicum Huber ex Ducke，俗称Paricá）与掌叶号角树（Cecropia palmata Willd，俗称Embaúba）的木材，搭配酚醛树脂（phenol-formaldehyde）与单宁醛树脂（tannin-formaldehyde）两类胶粘剂，结合不同单板（veneer）配比方案，生产单板与室外用胶合板（plywood）的技术可行性。试验用材林木采自帕拉州多姆埃利塞乌市（Dom Eliseu）辖区内通过林隙补植营建的人工林区域。湿地松（Pinus elliottii）木材作为对照试样，由巴拉那州伊拉蒂市（Irati）的一家企业捐赠。试验板材分别以三种单树种纯材制备，同时设置两组Paricá与Embaúba的混合配比方案，采用单线施胶量145 g·m⁻²的工艺参数。其中Paricá的单板出材率为80.03%，Embaúba的单板出材率为46.37%；仅采用Embaúba纯材、或与Paricá混合搭配并以酚醛树脂胶合的板材，其性能满足室外使用的工艺要求，且为所有配比方案中综合性能最优的组别。就本次试验所用施胶量而言，单宁醛树脂未表现出理想性能，因此酚醛树脂为适配该类板材的最优胶粘剂。