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US 4,184,845 AGranted
Process for reduction of lignin color
AssigneeWestvaco Corporation
InventorStephen Y. Lin
Life of this patent
Estimating the term…
Abstract
Disclosed herein is a two-step process for reducing the color of sulfonated alkali lignins and lignosulfonates by at least 80% which comprises, blocking at least 90% of the free-phenolic hydroxyl groups in the lignin and then subjecting the blocked lignins to oxidative action by air, molecular oxygen or hydrogen peroxide. The thus treated lignins are useful as dispersants for disperse dyes and vat dyes.
Claims7
A two-step process for producing light colored lignin which comprises;
- (a) reacting a sulfonated alkali lignin or lignosulfonate with from 1 to 20 moles of a member selected from the group consisting of alkylene oxides, halogen-containing alkyl alcohol, alkyl sulfonate and alkylene carbonate at a temperature from 0.degree. C. to 200.degree. C. until at least 90% of the phenolic hydroxyl groups are blocked and thereafter,
- (b) treating said blocked lignin with an oxidant until the original color of said lignin is made lighter by at least 80%.
Dependencies are inferred from the claim text.