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US 12,331,150 B2Granted
Process for preparing a solution of lignin in an aqueous medium
AssigneeStora Enso OYJ
InventorsBen Nasli Bakir, Ashar Zafar, Jesper Ekström
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Abstract
The present invention relates to a process for lignin dissolution in which partial methylolation of lignin is carried out during the step of preparing a solution of lignin in an aqueous medium comprising alkali and phenol. The lignin prepared according to the process of the present invention can be used to manufacture lignin-based phenolic resins, which are particularly useful in the manufacture of laminates.
Claims5
A method for dissolving lignin in an aqueous medium comprising the steps of:
- a) mixing lignin, alkali, phenol and formaldehyde in an aqueous medium;
- b) mixing until a solution of the lignin in the aqueous medium has been obtained;
- wherein a molar ratio between the formaldehyde and a total amount of the phenol and lignin monomer, based on an average lignin monomer molecular weight, is 0.4 or less, wherein the molar ratio between the formaldehyde and the total amount of the phenol and lignin monomer is calculated based on an average lignin monomer molecular weight of 190 g/mol, and
- wherein the lignin has been isolated from black liquor and purified before step a).
1 more element
Dependencies are inferred from the claim text.