杨木基电工层压木制备工艺的优化

采用杨木单板浸渍酚醛树脂（PF）制备电工层压木，探讨浸渍时间、树脂固含量、浸渍温度、单板厚度、单板含水率对杨木单板浸胶量的影响，并对比分析恒温干燥、阶梯升温干燥、三段式干燥等干燥模式下浸渍杨木单板的树脂预固化度和挥发分含量，通过正交试验研究了热压压力、热压时间、热压温度以及组坯方式等工艺因素对电工层压木密度、静曲强度、击穿电压和冲击强度4个指标的影响，优化了杨木基电工层压木的制备工艺。电工层压木的优化制备工艺为：将杨木单板在常温下用40%固含量的PF浸渍30 min，然后将浸渍后的杨木单板在40 ℃干燥5 min、60 ℃干燥15 min和55 ℃干燥10 min，最后进行纵横交错组坯，在热压温度140 ℃、热压压力4 MPa、热压时间1.4 min/mm的条件下热压。在此工艺条件下制备的杨木基电工层压木的密度为1.21 g/cm3，静曲强度为132.11 MPa，击穿电压为42.9 kV，冲击强度为15.4 kJ/m2。
Electrical laminated boards were prepared by poplar veneer impregnated with phenol formaldehyde (PF) resin. The influence of the impregnation time, resin solid content, impregnation temperature, veneer thickness, veneer moisture content on poplar veneer impregnation were studied. The effects of constant temperature drying, stepwise heating drying, three？？stage drying on the resin pre？？curing degree and volatile content of the veneers were compared. The effects of hot pressing pressure, hot pressing time, hot pressing temperature and layup process on density, modulus of rupture (MOR), breakdown voltage and impact strength of electrical laminated wood were researched. The optimal preparation process of electrical laminated wood was obtained as follows: the poplar veneer was impregnated in PF resin of 40% solid content for 30 min at room temperature.They were then dried at 40 ℃ for 5 min, 60 ℃ for 15 min, and 55 ℃ for 10 min, respectively.The veneer was assembled by crisscross setting way and hot？？pressed at 140 ℃ with the pressure of 4 MPa and pressing time of 1.4 min/mm. The density, MOR, breakdown voltage and impact strength were 1.21 g/cm3, 132.11 MPa, 42.9 kV and 15.4 kJ/m2,respectively for poplar？？based electrical laminated wood manufactured by the optimal preparation process