Acetylation of lignocellulosic materials
AssigneeThe United States of America as represented by the Secretary of Agriculture
InventorsRoger M. Rowell, Rune Simonson, Anne-Marie Tillman
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Abstract
Reaction of lignocellulosic material with uncatalyzed acetic anhydride in the absence of any cosolvent is disclosed. The process improves dimensional stability and resistance to biological attack of the lignocellulosic material. Lignocellulosic material is treated by exposure to liquid acetic anhydride for at least a short period of time, after which it is then heated to acetylate the material. The excess anhydride and byproduct acetic acid can be removed by vacuum.
Claims18
A method for catalyst-free acetylation of lignocellulosic material, comprising the steps of:
- contacting lignocellulosic material in the form of veneer, chips, flakes, fibers or particles with a liquid reactant consisting essentially of acetic anhydride and from about 10 percent to about 55 percent by volume acetic acid;
- heating the reactant-contacted lignocellulosic material at a temperature of up to 120.degree. C. for a time sufficient to acetylate said material, the time of heating being from 1 to 5 hours;
- and,
- removing from the resulting acetylated lignocellulosic material unreacted acetic anhydride and acetic acid.
A method as described in claim 14 wherein the unreacted acetic anhydride and acetic acid is removed by a vaporization with a hot gas flow followed by condensation of the resulting vapors.
Dependencies are inferred from the claim text.