Abstract:

Lignin amine(AL) was prepared by modifying corn cob via Mannich reaction, and then AL was mixed with water-based polyamide(PAE) and polyethylene glycol diglycidyl ether(PEGDE). Soybean meal was used as raw material to prepare soybean gum with high solid content by AL/PAE/PEGDE modification. The properties of soybean gum were characterized and tested, and the FT-IR results showed that the absorption peak of amide Ⅰ of the soybean meal adhesive modified with AL, PAE, and PEGDE after curing shifted from 1632 cm^-1 to 1640 cm^-1, and amide Ⅱ shifted from 1533 cm^-1 to 1538 cm^-1. And the shift suggested that the cured adhesive possessed a dense and cross-linking structure. The TGA results also showed that the network structure between PAE, PEGDE, AL, and protein molecules was more compact, and the rheological behavior analysis showed that the cured soybean meal adhesive had the characteristics of pseudoplastic fluid. The solid content in the modified adhesive was as high as 42.5%, while the apparent viscosity was simply 3 746 mPa·s, which was suitable for application in plywood industry. The wet bonding strength of the prepared plywood reached 0.86 MPa and the pass rate was 100%, which meet the national standard for type II plywood(bonding strength≥0.70 MPa, and the pass rate≥90%).

Key words: corncob lignin, amination, soybean meal adhesive, high solid content, bonding strength