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CA-3174099-C - METHOD FOR PRODUCING OXIDIZED LIGNINS AND SYSTEM FOR PRODUCING OXIDIZED LIGNINS

CA3174099CCA 3174099 CCA3174099 CCA 3174099CCA-3174099-C

Abstract

The invention relates to a method for producing oxidized lignins.

Inventors

  • Dorte Bartnik Johansson
  • Jens-Uwe Wichmann

Assignees

  • ROCKWOOL A/S

Dates

Publication Date
20260505
Application Date
20200403

Claims (20)

  1. 1. A method for producing oxidized lignins comprising bringing into contact - a component (i) comprising one or more lignins, - a component (ii) comprising ammonia and/or one or more amine components, and/or any salt thereof and/or an alkali and/or earth alkali metal hydroxide, such as sodium hydroxide and/or potassium hydroxide, - a component (iii) comprising one or more oxidation agents, and - optionally a component (iv) in form of one or more plasticizers, and allowing a mixing/oxidation step, wherein an oxidised mixture is produced, followed by an oxidation step, wherein the oxidised mixture is allowed to continue to react for a dwell time of 1 second to 10 hours, such as 10 seconds to 6 hours, such as 30 seconds to 2 hours.
  2. 2. A method according to claim 1, wherein - component (i) and component (ii), or - component (i) and component (ii) and component (iii), or - component (i) and component (ii) and component (iv), or - component (i) and component (ii) and component (iii) and component (iv), are brought into contact with each other in a premixing step.
  3. 3. A method according to claim 1 or 2, wherein component (i) comprises one or more kraft lignins, one or more soda lignins, one or more lignosulfonate lignins, one or more organosolv lignins, one or more lignins from biorefining processes of lignocellulosic feedstocks, or any mixture thereof.
  4. 4. A method according to any of the preceding claims, wherein component (iii) comprises one or more oxidation agents in form of hydrogen peroxide, organic or inorganic peroxides, molecular oxygen, air, CA 03174099 2022- 9- 29 WO 2021/197629 PCT/EP2020/059651 48 ozone, halogen containing oxidation agents, or any mixture thereof.
  5. 5. A method according to any of the preceding claims, wherein component (iv) comprises one or more plasticizers in form of polyols, such as carbohydrates, hydrogenated sugars, such as sorbitol, erythriol, glycerol, monoethylene glycol, polyethylene glycols, polyethylene glycol ethers, polyethers, phthalates and/or acids, such as adipic acid, vanillic acid, lactic acid and/or ferullic acid, 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. 6. A method according to any of the preceding claims, comprising the bringing into contact of components (i), component (ii), component (iii) and a component (v) in form of an oxidation catalyst, such as one or more transition metal catalysts, such as an iron containing catalyst, such as iron sulfate, such as manganese, palladium, selenium, tungsten containing catalysts.
  7. 7. A method according to any of the preceding claims, wherein - a component (i) comprises one or more lignins - a component (ii) comprises ammonia - a component (iii) comprises one more oxidation agents in form of hydrogen peroxide, - a component (iv) comprises polyethylene glycol, wherein the mass ratios of lignin, ammonia, hydrogen peroxide and polyethylene glycol are such that the amount of ammonia is 0.01 to 0.5 weight parts, such as 0.1 to 0.3, such as 0.15 to 0.25 weight parts ammonia (25 weight% solution in water), based on the dry weight of lignin, and wherein the amount of hydrogen peroxide (30 weight% solution in water) is 0.025 to 1.0 weight parts, such as 0.07 to 0.50 weight parts, such as 0.15 to 0.30 weight parts hydrogen peroxide, based on the dry weight of lignin, and wherein the amount of polyethylene glycol is 0.03 to 0.60 weight parts, such as 0.07 to 0.50 weight parts, such as 0.10 to 0.40 weight parts polyethylene glycol, based on the dry weight of lignin. CA 03174099 2022- 9- 29 WO 2021/197629 PCT/EP2020/059651 49
  8. 8. A method according to any of the preceding claims, wherein the method comprises the steps of: - a step of providing component (i) in form of an aqueous solution and/or dispersion of one more lignins, the lignin content of the aqueous solution being 5 to 90 weight-%, such as 10 to 85 weight- %, such as 15 to 70 weight-%, based on the total weight of the aqueous solution; - a pH adjusting step by adding component (ii); - a step of adding component (iv); - a mixing/oxidation step by adding component (iii).
  9. 9. A method according to claim 8, wherein the pH adjusting step is carried out so that the reaction mixture is having a pH > 9, such as 10, such as 10.5.
  10. 10. A method according to any of the claims 8 - 9, wherein during the mixing/oxidation step the temperature is allowed to raise from 20 C to 80 C, such as 35 C to 70 C and is then controlled in the range of 40 C to 65 C, such as 40 C to 60 C.
  11. 11. A method according to any of the claims 8 - 10, wherein the mixing/ oxidation step is carried out for a time of 0,01 seconds to 10 seconds, such as 0,05 seconds to 5 seconds, such as 0,1 seconds to 2 seconds.
  12. 12. A method according to any of the preceding claims, wherein the viscosity of the oxidized lignin has a value of 100 cP to 100.000 cP, such as a value of 500 cP to 50.000 cP, such as a value of 1.000 cP to 25.000 cP.
  13. 13. A method according to any of the preceding claims, wherein the method is performed as a continuous process.
  14. 14. Oxidized lignin prepared by a method according to any of the preceding claims. CA 03174099 2022- 9- 29 WO 2021/197629 PCT/EP2020/059651
  15. 15. Oxidized lignin according to claim 14 comprising ammonia-oxidized lignin (AOL).
  16. 16. Use of the oxidized lignin according to claim 14 or 15 as a component in a binder composition, in particular as an aqueous binder composition for mineral fibers.
  17. 17. Use of the oxidized lignin according to claim 14 or 15 as a component in an aqueous adhesive composition for lignocellulosic materials, such as wood.
  18. 18. A system (20) for performing the method of claims 1 - 13, comprising: - at least one rotor-stator device (1, la, lb, 3), - one or more inlets (5, 6, 7) for water and components (i) and (ii), - one or more outlets (12) of the at least one rotor-stator device (3), - at least one reaction device, in particular at least one reaction tube (9), which is arranged downstream in the process flow direction to the at least one or more of the outlets (12).
  19. 19. A system (20) according to claim 18, comprising: one or more inlets (8, 11) for component (iii) and/or component (iv).
  20. 20. A system (20) according to claim 18 or 19, wherein the inlets (6, 7, 8) for components (i), (ii) and (iv) are inlets of a premixing device (1, la, lb), in particular of an open rotor-stator device, whereby the system (20) furthermore comprises a, in particular an additional, rotor-stator device (3), said additional rotor-stator device (3) having an inlet (11) for component (iii) and at least one outlet (12).

Description

WO 2021/197629 PCT /EP2020/059651 Method for producing oxidized lignins and system for producing oxidized lignins Field of the Invention The present invention relates to a method for producing oxidized lignins, an oxidized lignin prepared by such a method and the use of such oxidized lignins as a component in a binder composition, such as an aqueous binder composition for mineral fibers; such as a component in an aqueous adhesive composition for lignocellulosic materials. The present invention also relates to a system for performing the method according to the present invention. Background of the Invention Lignin is a class of complex organic polymers found as structural materials in vascular plants. It forms about 20-35 % of the dry mass of wood and is therefore, except cellulose, the most abundant polymer found in nature. Lignin is a side product in the process of paper production and therefore vast amounts of lignin are produced in the paper making industry. The lignin separated in the paper making process is usually burnt as fuel. In view of this, lignin is a very inexpensive product, which makes it an attractive starting material. Fig. 1 shows a section from a possible lignin structure. Accordingly, lignin represents an attractive feedstock due to availability and potentially low price. It is also the main renewable aromatic source. Lignin is CA 03174099 2022-9-29 WO 2021/197629 PCT /EP2020/059651 2 composed of three primary units (often called monolignols) linked through ether and C-C bonds (Figure 2). Representation of these three monolignols depends on the source material although guaiacyl (G) is the most abundant in softwood lignin, guaiacyl and syringyl in hardwood lignin while all three are fairly represented in grasses. One potential use of lignins is the use in binders, such as binders for mineral fibres. There are several important characteristics of lignin in relation to binders. Lignin is an aromatic polymer with high glass transition temperature (Tg). Lignin thermally decomposes over a wide range of temperatures as different oxygen containing moieties possess different stability and reactions that are occurring can be consecutive but also competing due to hindered structure of lignin polymer. Lignin surface chemistry properties (like surface tension components) are similar to the same properties of cured phenol formaldehyde (PF) binders. This situation makes the reasonable assumption that adhesion properties of lignin can be at the similar level as those of long time used PF binders in insulation materials but also in binding wood etc. However, lignin is an inherently heterogeneous material and on top of that, the lignin properties and structures are different based on various techniques being employed in extracting lignin from biomass. The differences come in terms of structure, bonding pattern of lignin aromatic units, molecular weight etc. The reactive functional group being present in high amounts in a typical lignin is the hydroxyl group, being either phenolic or aliphatic hydroxyl group. The presence of phenolic hydroxyl group also activates the aromatic ring towards reactions with aldehydes. Overall, it can be said that lignin structure limits the choice of cross-linkers to most often environmentally compromised reagents and therefore limits the possibility to use lignin as a starting material in processes, which include chemical reactions. CA 03174099 2022-9-29 In order to utilize lignins as starting materials for different uses, chemical derivatizations of lignins have been proposed. One of the proposed ways of derivatizing lignin is oxidation. Oxidation of lignin is usually carried out with strong oxidation agents in the presence of alkali metal hydroxides. WO 2021/197629 PCT /EP2020/059651 3 However, one problem associated with the previously known oxidized lignins is that they are less fire resistant when used in products where they are comprised in a binder composition, compared to the underivatized lignins, said underivatized lignins rendering them unsuitable for many applications. A further problem associated with these previously known oxidized lignins is that residual alkali metal hydroxide in the product tends to render the products unstable and makes them susceptible to changing their properties in an aging process. Further, previously known derivatization processes for lignins often lack high throughput and are therefore not suitable for the production of derivatized lignins in amounts suitable for industrial mass production. Summary of the Invention Accordingly, it was an object of the present invention to provide a process for the derivatization of lignins, which overcomes the disadvantages of previously known derivatization processes of a lignin. In particular, it was an object of the present invention to provide a process for the derivatization of lignins that result in derivatized lignins having desired reactivity and at the same time are more fire resistant when us