无醛木材胶粘剂粘接强度和稳定性的影响因素研究

Influence factors to the bond strength and stability of aldehyde-free wood adhesive

以聚乙烯醇(PVA)为主剂,加入二苯基甲烷二异氰酸酯(MDI)溶液,硅酸钠及羧甲基纤维素(CMC)等助剂,制备一种无醛水性环保型木材胶粘剂。以拉伸剪切强度、耐水性、胶粘剂的适用期为考核指标,通过正交设计优化了MDI溶液用量、硅酸钠溶液用量、羧甲基纤维素用量等参数。结果表明,MDI溶液用量对剪切强度、耐水性的影响最显著;硅酸钠溶液用量对胶粘剂的适用期影响最显著,加热和加压对剪切强度影响较大,提高温度对拉伸剪切强度的影响比施加压力对强度的影响更显著。固化条件对拉伸剪切强度的影响顺序为:热压固化>加热固化>冷压固化>室温固化。为保证胶粘剂有一定的适用期,具有较高的强度和较好的耐水性,最终确定最优方案为:MDI溶液用量12%,硅酸钠溶液用量10%,羧甲基纤维素用量15%,并采用热压固化。

A kind of aldehyde-free water-based wood adhesive was prepared by taking polyvinyl alcohol （PVA） as the major agent, and methylene diphenyl diisocyanate solution （MDI）,sodium silicate and carboxymethyl cellulose （CMC） as the auxiliary agents. Some parameters such as MDI solution dosage, sodium silicate dosage and carboxymethyl cellulose dosage were optimized by orthogonal design,taking tensile shear strength,water resistance and probationary period as appraising standard. The result shows that the influence of MDI solution dosage to tensile shear strength and water resistance is the biggest;the sodium silicate dosage has the biggest influence to the probationary period of adhesive：heating and pressing has relatively big influence to the tensile shear strength,and temperature increasing has bigger influence to the tensile shear strength than pressing. The sequence of curing conditions to tensile shear strength is：hot-pressing curing 〉thermo -curing 〉cold -pressing curing〉room-temperature curing. The optimized technologic conditions to ensure the adhesive have proper probationary perlod,higher strength and better water resistance are as follows： MDI solution dosage is 12%,sodium silicate dosage is 10% and carboxymethyl cellulose dosage is 15%,and hotpressing curing is adopted.