摘要
为缓解酚醛树脂原料对石油及其衍生物的依赖，降低成本，拓展生物质材料的应用领域，提高其利用价值，本论文以杉木为原料，在苯酚中经酸催化降解得到液态杉木苯酚液化物，较系统地研究了液化物树脂合成工艺对树脂理化和胶合性能的影响；探讨不同热压工艺参数对杉木液化物树脂胶合性能的影响，并通过正交试验及验证试验获得其最佳工艺条件；借助FTIR等手段初步分析了木材液化及树脂化的基团变化和反应历程；参照常规酚醛树脂对树脂的成本进行了评价。主要结论如下：
1．随着甲醛/苯酚(F/P)摩尔比的提高，两种料液比(1：2和1：3)条件下液化物树脂中游离苯酚均表现出明显下降的趋势，游离甲醛基本呈线性增长的趋势；提高氢氧化钠/苯酚(NaOH/P)摩尔比使得料液比1：2条件下树脂中游离酚含量逐渐增大，而对料液比1：3条件影响不明显，提高碱加入量能有效降低树脂中游离醛含量；提高树脂化温度能显著降低树脂中游离酚和游离醛的含量。
2．随甲醛加入量的增加树脂胶合强度先减小后增大，摩尔比1.8时胶合强度最低；胶合强度随NaOH/P摩尔比的增大而增大，但反应体系pH过高反而会降低胶合强度；随着树脂化温度的升高，料液比1：2在80℃时胶合强度达到最大，而料液比1：3树脂在树脂化温度85℃处胶合强度最低；研究结果表明杉木液化物树脂(LWR)最佳配方为：料液比1：2，F/P摩尔比1.8，NaOH/P摩尔比0.7，树脂化温度80℃。
3．杉木液化物树脂较优热压工艺条件为：热压温度125℃，热压压力1.0MPa，热压时间1.0min/mm，固化剂加入量0.1％。
4．杉木液化物树脂各项理化性能与常规PF相近，均满足国标GB/T 14732-93要求；压制的五层杨木胶合板胶合强度达到Ⅰ类胶合板要求，甲醛释放量(0.2mg·L~(-1))远低于胶合板国标GB 9486-2004中的E_0级要求。液化反应中苯酚与木材组分发生了明显酚化反应，酸性条件下纤维素的晶格结构遭到破坏，半纤维素被降解，木素液化降解成低分子物质；杉木液化物树脂FTIR谱图具有典型酚醛树脂的特征吸收峰。杉木液化物树脂的原料成本比常规PF低15％左右。
In order to release dependency of synthesizing phenol-formaldehyde resins on petrol and its ramification, reduce cost, widen application fields and improve the utilization of biomass materials, we carry out the research on preparation of resins from liquefied wood in phenol in presence of sulfuric acid. In this paper, effects of resinfication factors on chemical and bonding properties of resins were systemically studied; optimum hot-press processing parameters were defined by orthogonal test; changes of groups and mechanism of reaction were analysed by FTIR; cost of liquefied Chinese Fir resins was also calculated.The results are as follows:
1) With increasing F/P molar ratio, free phenol content of resin remarkablely decreased on both liquefaction condition (wood/phenol=1:2, 1:3), free formaldehyde content linearly increased; with rise of NaOH/P molar ratio, free phenol content of resin from wood/phenol 1:2 liquefied product increased, but that of resin from wood/phenol 1:3 liquefied product showed no obvious changes; adding alkalis was good for reducing free formaldehyde content of resin; both free phenol and formaldehyde of resin obviously decreased with enhancing resinification temperature.
2) Bond strength decreased with adding formaldehyde then were improved, and showed minimum value at F/P molar ratio 1.8; bond strength increased with rise of NaOH/P molar ratio, but excess alkalis would lead to bond strength dropping; with enhancing resinification temperature, bond strength of the resin from wood/phenol 1:2 liquefied product arrived at the maximum at 80℃ and that from wood/phenol 1:3 liquefied produc reached the minimum at 85℃; results showed optimum formation of liquefied Chinese Fir resin (LWR) were wood/phenol 1:2, F/P molar ratio 1.8, NaOH/P molar ratio 0.7, resinification temperature 80℃.
3) The optimum hot press parameters for LWR were as follow: hot-press temperature 125℃,
press 1.0MPa, hot-press time 1.0min/mm, quantity of solidified agent 0.1%.
4) The Physics and Chemistry Performance of liquefied Chinese Fir resin was similar to that of traditional PF resins and met the requirement of GB/T 14732-93. Bond strength of the poplar three-layer plywood bonded with LWR satified the demands of I level. Free formaldehyde content of plywood was 0.2mg·L~(-1) which is lower than the E_0 level set by GB 9486-2004. Phenolated reaction between phenol and wood conponets during liquefaction in presence of sulfuric acid; crystal lattice of cellulose was destroyed; hemicellulose and lignin were degraded to low molecule substance; FTIR of LWR showed typical absorbing peaks as PF resins. The cost of LWR was 15% lower than that of traditional PF.
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