金属离子对大豆基木材胶黏剂胶合性能的影响

Effects of Metal Ions on the Bond Properties of Soybean-based Wood Adhesive

使用聚酰胺多胺-环氧氯丙烷树脂(PAE)溶液、脱脂豆粉和金属氯化物溶液调制无醛大豆基木材胶黏剂,采用傅里叶红外光谱、热重分析、胶合板性能评价等方法,探究金属离子种类、用量及其加入方式对大豆胶黏剂胶合性能的影响。结果表明:金属离子对大豆胶黏剂的胶合性能有着重要影响。添加Mg2+与Fe3+能够提高胶接耐水性能,而添加Na+、Ca2+、Cu2+、Al3+等金属离子会不同程度降低大豆胶黏剂耐水性能;Mg2+可促进大豆蛋白伸展而且不影响PAE树脂的交联特性,使脱脂豆粉能与PAE树脂产生更好的交联反应,赋予大豆胶黏剂更好的胶接耐水性能;当Mg2+添加量为胶黏剂的1.5 wt%(以1 wt%MgCl2溶液计)时,压制的胶合板28 h“煮-烘-煮”湿强度达到1.16 MPa,较未添加金属离子大豆胶黏剂的湿强度提高11.5%,然而Mg2+的添加顺序对大豆胶黏剂的胶合性能基本无影响。

Formaldehyde-free soybean adhesives for wood bonding were prepared from polyamide polyamineepichlorohydrin(PAE)resin,defatted soybean flour and metal chloride solution.The effects of species,addition level,and addition manner of metal ions on bond properties PAE-modified soybean adhesive were investigated based on the evaluations using Fourier transform infrared spectrometry(FTIR),thermogravimetric analysis(TGA)and plywood bond properties evaluation.Test results showed that species of metal ions had important effects on the bond properties of soybean adhesive.Addition of metal irons such as Mg2+and Fe3+could improve the water resistance of bondlines,while addition of other metal irons such as Na+,Ca2+,Cu2+and Al3+resulted in worse water resistance.Because magnesium ion could promote protein unfolding and have no effect on crosslinking characteristic of PAE resin,the soybean protein could be more effectively crosslinked by PAE resin and resulted in better water resistance of modified adhesive.When the addition level of Mg2+was 1.5 wt%on mass basis of 1 wt%MgCl2 solution over liquid adhesive,the modified adhesive had best water resistance in terms of a 28 h boiling-dry-boiling wet strength of 1.16 MPa or an increase by 11.5%.However,addition sequence of Mg2+solution had no effects on bond property of modified adhesive.