Method for producing oxidized lignins
The present invention is directed to a method for producing oxidized lignins.
1. A method for producing oxidized lignins, wherein the method comprises contacting
a component (i) comprising one or more lignins,
a component (ii) comprising ammonia,
a component (iii) comprising one or more oxidizing agents which include hydrogen peroxide,
a component (iv) comprising one or more plasticizers which include polyethylene glycol,
mass ratios of lignin, ammonia, hydrogen peroxide and polyethylene glycol being such that based on 1 part by weight of dry lignin an amount of ammonia is from 0.01 to 0.5 parts by weight, an amount of hydrogen peroxide, 30 weight % solution in water, is from 0.025 to 1.0 parts by weight, and an amount of polyethylene glycol is from 0.03 to 0.60 parts by weight.
2. The method of claim 1 , wherein component (i) comprises one or more lignins selected from kraft lignins, soda lignins, lignosulfonate lignins, organosolv lignins, lignins from biorefining processess of lignocellulosic feedstocks, or any mixture thereof.
3. The method of claim 1 , wherein component (i) comprises one or more kraft lignins.
4. The method of claim 1 , wherein component (iii) further comprises one or more oxidizing agents selected from organic or inorganic peroxides, molecular oxygen, ozone, halogen containing oxidation agents, or any mixture thereof.
5. The method of claim 1 , wherein component (iv) further comprises one or more plasticizers selected from polyols, hydrogenated sugars, glycerol, monoethylene glycol, polyethylene glycol ethers, polyethers, phthalates and/or acids, acrylic polymers, polyvinyl alcohol, polyurethane dispersions, ethylene carbonate, propylene carbonate, lactones, lactams, lactides, acrylic based polymers with free carboxy groups and/or polyurethane dispersions with free carboxy groups, urea, or any mixtures thereof.
6. The method of claim 1 , wherein component (iv) further comprises one or more plasticizers selected from polyols, hydrogenated sugars, glycerol, monoethylene glycol, polyvinyl alcohol, acrylic based polymers with free carboxy groups and/or polyurethane dispersions with free carboxy groups, urea, or any mixtures thereof.
7. The method of claim 1 , wherein the method comprises contacting component (i), component (ii), component (iii) and a component (v) in the form of an oxidation catalyst.
8. The method of claim 1 , wherein the method comprises
providing component (i) in the form of an aqueous solution and/or dispersion of one more lignins, a lignin content of the aqueous solution being from 5 to 90 weight-%, based on a total weight of the aqueous solution;
adjusting a pH of the solution and/or dispersion by adding component (ii);
addition of component (iv);
whereafter component (iii) is added.
9. The method of claim 8 , wherein the pH is adjusted to a value of ≥9.
10. The method of claim 8 , wherein during an oxidation a temperature is allowed to rise to more than 35° C. and is then controlled in a range of 35-150° C.
11. The method of claim 10 , wherein an oxidation is carried out for a time of from 1 second to 24 hours.
12. The method of claim 1 , wherein a viscosity of the oxidized lignins is from 100 cP to 100,000 cP.
13. The method of claim 1 , wherein the method is performed as a continuous process.
14. The method of claim 1 , wherein the method affords an oxidized lignin having a carboxylic acid group content of from 0.05 to 10 mmol/g, based on a dry weight of component (i).
15. The method of claim 14 , wherein the method affords an oxidized lignin having a carboxylic acid group content of from 0.1 to 5 mmol/g.
16. The method of claim 14 , wherein the method affords an oxidized lignin having a carboxylic acid group content of from 0.20 to 2.0 mmol/g.
17. The method of claim 1 , wherein the method affords an oxidized lignin having an average carboxylic acid group content of more than 1.5 groups per macromolecule of component (i).
18. The method of claim 1 , wherein the method affords an oxidized lignin having an average carboxylic acid group content of more than 2 groups per macromolecule of component (i).
19. The method of claim 1 , wherein the method affords an oxidized lignin which is suitable as a component of an aqueous binder composition for mineral fibers.
20. The method of claim 1 , wherein an apparatus comprising a rotor-stator device is used to carry out the contacting the component (i), the component (ii), the component (iii), and the component (iv).