Process and apparatus for modification of lignocellulosic materials and products of modified lignocellulosic materials obtained by the process

摘要

A process and apparatus for the preparation of a modified lignocellulosic material by
treating the lignocellulosic material in a first activator zone having an atmosphere of one or more acid anhydrides in vapour form in a gas at a gauge pressure of 0-50 kPag and a temperature of 100-160° C., and thentreating the lignocellulosic material in a second reactor zone having an atmosphere of a gas at a gauge pressure of 0-50 kPag and a temperature of 120-190° C., thereafterstripping the lignocellulosic material with steam or water in a stripper zone, andoptionally further processing.;The process is more efficient as compared with the prior art processes by providing a better access of the acid anhydrides to the sites of the reactive lignocellulosic hydroxyl groups (—OH), which are located on the internal surfaces of pores and capillary channels in the lignocellulose. Furthermore, the apparatus is relatively simple. This makes the inventive process and apparatus suitable for a cost-efficient preparation of modified lignocellulosic fibre in industrial scale.

主权项

1. A process for the preparation of a modified lignocellulosic material by contacting and reacting a lignocellulosic material with a modification agent, which contains acid anhydride, and stripping the modified lignocellulosic material to remove excess of modification agent and by-products, including the steps of
a) introduction of the lignocellulosic material into a first activator zone and treatment of the lignocellulosic material in the first activator zone having an atmosphere of the modification agent, which contains one or more acid anhydrides, in vapour form in a gas at a gauge pressure of 0-50 kPag and a temperature of 100-160° C., b) transfer of the lignocellulosic material from the first activator zone into a second reactor zone and treatment of the lignocellulosic material in the second reactor zone having an atmosphere of a gas at a gauge pressure of 0-50 kPag and a temperature of 120-190° C., c) transfer of the lignocellulosic material from the second reactor zone into a stripper zone and stripping of the lignocellulosic material with steam or water in the stripper zone, d) optionally transfer to further processing, wherein the modification agent introduced into the first activator zone has a content of hydrated acids below 3% by weight.