Abstract: Using the dilute acid hydrolysis lignin and straw alkali lignin as materials and selecting many kinds of polyols as esterification agents, a series of hydroxyl containing lignin polyesters with various chain length were synthesized. The rigid polyurethane foam was prepared using lignin polyesters as polyols component.Experimental results showed the properties of lignin poly-esters were as follows: the viscosity of lignin polyesters: 3 000-5 000 cP·s/20℃,hydroxyl value:380-450 mg/g, acid value: < 5 mg/g. The properties of lignin foam: apparent density: 0.03-0.05 g/cm³, compression strength: >0.15 MPa, thermal conductivity: 0.023 W/(M·K), water adsorption:3%. The physical properties of lignin polyurethane foam meet the demands of industry and daily life for heat insulating material.

Key words: lignin, polyester, foam