Savov Viktor, Valchev Ivo, Antov Petar, Yordanov Ivaylo, Popski Zlatomir
Faculty of Forest Industry, University of Forestry, 1797 Sofia, Bulgaria.
Faculty of Chemical Technologies, University of Chemical Technology and Metallurgy, 1757 Sofia, Bulgaria.
Polymers (Basel). 2022 Apr 27;14(9):1768. doi: 10.3390/polym14091768.
This study aimed to propose an alternative technological solution for manufacturing fiberboard panels using a modified hot-pressing regime and hydrolysis lignin as the main binder. The main novelty of the research is the optimized adhesive system composed of unmodified hydrolysis lignin and reduced phenol-formaldehyde (PF) resin content. The fiberboard panels were fabricated in the laboratory with a very low PF resin content, varying from 1% to 3.6%, and hydrolysis lignin addition levels varying from 7% to 10.8% (based on the dry wood fibers). A specific two-stage hot-pressing regime, including initial low pressure of 1.2 MPa and subsequent high pressure of 4 MPa, was applied. The effect of binder content and PF resin content in the adhesive system on the main properties of fiberboards (water absorption, thickness swelling, bending strength, modulus of elasticity, and internal bond strength) was investigated, and appropriate optimization was performed to define the optimal content of PF resin and hydrolysis lignin for complying with European standards. It was concluded that the proposed technology is suitable for manufacturing fiberboard panels fulfilling the strictest EN standard. Markedly, it was shown that for the production of this type of panels, the minimum total content of binders should be 10.6%, and the PF resin content should be at least 14% of the adhesive system.
本研究旨在提出一种替代性技术解决方案，以使用改良的热压工艺和水解木质素作为主要粘合剂来制造纤维板。该研究的主要新颖之处在于由未改性的水解木质素和降低的酚醛（PF）树脂含量组成的优化粘合剂体系。在实验室中制造纤维板时，PF树脂含量非常低，在1%至3.6%之间变化，水解木质素添加量在7%至10.8%之间变化（基于干木纤维）。采用了一种特定的两阶段热压工艺，包括初始1.2MPa的低压和随后4MPa的高压。研究了粘合剂体系中粘合剂含量和PF树脂含量对纤维板主要性能（吸水性、厚度膨胀率、弯曲强度、弹性模量和内结合强度）的影响，并进行了适当的优化，以确定符合欧洲标准的PF树脂和水解木质素的最佳含量。得出的结论是，所提出的技术适用于制造符合最严格EN标准的纤维板。值得注意的是，结果表明，对于生产这种类型的板材，粘合剂的最低总含量应为10.6%，PF树脂含量应至少占粘合剂体系的14%。
