METHOD FOR PRODUCTION OF MOLDED MATERIALS ON THE BASE OF HYDROLYTIC LIGNIN Russian patent published in 1998 - IPC

FIELD: manufacturing of molded materials. SUBSTANCE: method involves cooperative activation of hydrolytic lignin and wood particles, the process is carried out with the help of 25 % aqueous ammonium hydroxide (its expense being 12-26 % of weight of absolutely dry components). Quantities of hydrolytic lignin and wood particles are 23-46 mass % and 50-71 mass %, respectively. Activation takes place at 70-100 C within 60-120 min. When activation is completed thus prepared mass is dried at 80-100 C till its moisture content is 8-12 %. Then mixing with 50 % aqueous solution of thermoreactive carbamide-formaldehyde resin is carried out, quantity of said resin being 4-6 mass %. Then briquettes are formed of thus prepared molded composition, the process takes place at 25 ± 5 C and under pressure 30 ± 1 MPa. Then articles are formed at 180 ± 5 C and under pressure in 15 ± 1 MPa, sustaining period being 0.8 ± 0.1 min per 1 mm of thickness of desired article. Bending strength of molded articles is 24-28 MPa, Brinell hardiness of molded articles is 18-25 units and their water absorption in 24 h is 1.4-1.1 %. EFFECT: improved quality of desired articles; simplified process for production of molded materials. 2 tbl