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US 5,177,169 AGranted
Method for recovering and using lignin in adhesive resins
AssigneeColorado State University Research Foundation
InventorHerbert A. Schroeder
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AssigneeColorado State University Research Foundation
InventorHerbert A. Schroeder
Estimating the term…
Lignin, or a lignin derived material, which has been significantly demethylated (e.g., the demethylated lignin found in the raffinate produced as a by-product of dimethyl sulfide production which can be carried out using the spent liquor from wood pulping operations) can be isolated by a process wherein an organic solvent is added to a lignin-containing aqueous solution. The organic solvent is typically a polar, and at least a partially water-immiscible substance such as, for example, ethyl acetate. The resulting lignin-containing aqueous solution/organic solvent mixture is acidified to produce a water layer which is discarded and an organic solvent layer which contains the demethylated lignin. Upon its recovery, the demethylated lignin is dissolved in an alkaline solution to which an aldehyde source is added to produce a resol-type resin. The aldehyde source may be formaldehyde in solution, paraformaldehyde, hexamethylenetetramine, or other aldehydes including acetaldehyde, furfural, and their derivatives.
A method for employing demethylated lignin dissolved in a demethylated lignin-containing aqueous solution to produce a resol resin, said method comprising:
The method of claim wherein the polar, partially water immiscible organic solvent is a ketone selected from the group consisting of 2-butanone, 2pentanone, 3-pentanone, 2-hexanone and 3-hexanone.
Dependencies are inferred from the claim text.