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US 5,344,921 AGranted
Method for manufacturing lignin for carbon fiber spinning
AssigneeForestry and Forest Products Research Institute, Ministry of Agriculture, Forestry and Fisheries
InventorsKenichi Sudo, Kazumasa Shimizu
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Abstract
A method for manufacturing lignin for carbon fiber spinning, comprising subjecting to heat treatment in a non-oxidizing atmosphere a phenolated lignin obtained by phenolation of lignin dissolved out in delignification of a woody material, or a phenolated lignin derived from digestion of a woody material with a phenol.
Claims4
A method for manufacturing a lignin for carbon fiber spinning, which comprises
- a first step of phenolating lignin from wood by heatinq the lignin and phenolic solvent at the boiling point of the solvent to produce phenolated lignin, wherein said first step is conducted at atmospheric pressure without removing unreacted phenol during phenolation, and further
- a second step of heat treating the resultant reaction mixture in a non-oxidizing atmosphere under reduced pressure at a temperature and time sufficient for (a) polycondensation of the phenolated lignin, (b) removing unreacted phenol and (c) increasing the viscosity of the reaction mixture, wherein the heat treatment is conducted at a temperature ranging from 180.degree. to 300.degree. C. for 30 minutes to 6 hours under subatmospheric pressure.
Dependencies are inferred from the claim text.