核桃壳苯酚液化及其产物树脂化制备木材胶黏剂的研究

采用硫酸催化剂,考察了苯酚与核桃壳质量比等条件对核桃壳液化的影响。结果表明相同液化条件下,随着苯酚与核桃壳质量比从2∶1升至5∶1,残渣率从26.49%降至6.60%;随着浓硫酸加入量从2%增至4%、反应时间从5 min延至120 min、反应温度从100℃增至150℃,残渣率则分别从20.79%降至10.48%、48.84%降至15.62%、28.86%降至9.39%,游离酚含量分别从17.32%降至12.67%、41.71%降至10.25%、21.94%降至14.33%。同时,液化产物重均相对分子质量(MW)可降至706~1 030、分散度可降至1.04~1.25;液化产物中高相对分子质量部分随着苯酚与核桃壳质量比的增加有所降低,但随着浓硫酸加入量、液化反应时间和温度的增加而有所增加;核桃壳液化产物/苯酚/甲醛共缩聚树脂胶黏剂(WPF)与传统酚醛树脂胶黏剂(PF)的对比表明,WPF的胶接强度可达1.33 MPa,可作为胶合板用胶黏剂。

Study on Liquefaction of Walnut Shell in Phenol and Application of Its Resinification Product as Wood Adhesives

Liquefaction of walnut shell in phenol using sulfuric acid as catalyst was investigated under different conditions of mass ratio of phenol to walnut shell, dosage of catalyst, reaction time and temperature. Results showed that with the increasing of phenol/walnut shell ratio from 2/1 to 5/1, the amount of residue decreased from 26.49 % to 6.60 %. With dosage of catalyst from 2 % to 4 %, reaction time from 5 to 120 min and temperature from 100 to 150 ℃, the amounts of residue decreased from 20.79 % to 10.48 %, 48.84 % to 15.62 % and 28.86 % to 9.39 %, respectively; the contents of unreacted free phenol decreased from 17.32 % to 12.67 %,41.71 % to 10.25 % and 21.94 % to 14.33 %, respectively too. Weight average molecular weight (MW) and degree of polydispersity of resultants of liquefaction decreased to 706-1 030, 1.04-1.25, respectively. The high-molecular weight part of liquefaction product decreased with increasing of phenol/walnut shell ratio, but increased with the increasing of H2 SO4 concentration, reaction time and temperature. Compared to conventional phenol-formaldehyde (PF) resin adhesives, the liquefied walnut shell/phenol/formaldehyde co-condensed (WPF) resin can be used as adhesives for plywood with its bonding strength of 1.33 MPa.