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EP-4739838-A1 - AN AQUEOUS DISPERSION FOR BINDING AND COATING APPLICATIONS

EP4739838A1EP 4739838 A1EP4739838 A1EP 4739838A1EP-4739838-A1

Abstract

According to an example aspect of the present invention, here is provided an aqueous dispersion, and a film thereof, comprising an extract comprising suberin, and a dispersant comprising hemicellulose grafted with organic acids or their anhydrides. Further, there is provided a method of manufacturing such aqueous dispersion or film. In addition, the present invention relates to the use of such aqueous dispersion and film.

Inventors

  • KVIKANT, Minette
  • KOPPOLU, Rajesh
  • TOIVAKKA, MARTTI
  • XU, Chunlin

Assignees

  • Åbo Akademi

Dates

Publication Date
20260513
Application Date
20240704

Claims (20)

  1. 1. An aqueous dispersion comprising an extract comprising suberin, and a dispersant comprising hemicellulose grafted with organic acids or their anhydrides.
  2. 2. The aqueous dispersion according to claim 1, wherein the hemicellulose is galactoglucomannan (GGM), xylan, arabinogalactan, arabino-glucoronoxylan, xyloglucan, betaglucan, alpha-glucan or a combination thereof, preferably GGM or xylan.
  3. 3. The aqueous dispersion according to claim 1 or 2, wherein the hemicellulose is obtained by extraction, membrane filtration, hydrolysis, biosynthesis routes or by the combination thereof.
  4. 4. The aqueous dispersion according to any of the preceding claims, wherein the organic acids or their anhydrides comprise fatty acids, resin acids or a mixture thereof, preferably organic acids are naturally derived fatty acids.
  5. 5. The aqueous dispersion according to any of the preceding claims, wherein organic acids have a chain length in the range of C2 to C20.
  6. 6. The aqueous dispersion according to any of the preceding claims, wherein the organic acids or their anhydrides are activated organic acids or their anhydrides.
  7. 7. The aqueous dispersion according to any of the preceding claims, wherein the organic acids, preferably fatty acids, or their anhydrides are activated with carbonyldiimidazole.
  8. 8. The aqueous dispersion according to any of the preceding claims, wherein the hemicellulose is grafted with organic acids or their anhydrides through esterification reaction.
  9. 9. The aqueous dispersion according to any of the preceding claims, wherein the amount of hemicellulose is 0.1 to 50 wt.%, preferably 0.5 to 20 wt.%, more preferably 1 to 10 wt.% with respect to weight of dry suberin.
  10. 10. The aqueous dispersion according to any of the preceding claims, wherein the total solid content of the aqueous dispersion is in the range of 5 to 55 wt.%, preferably 15 to 50 wt.%, more preferably 20 to 40 wt.%, calculated from the total weight of the dispersion, the rest preferably being water.
  11. 11. The aqueous dispersion according to any of the preceding claims, wherein the pH of the dispersion is from 5.5 to 8, preferably from 6 to 7, more preferably 6 to 6.5.
  12. 12. A method of producing an aqueous dispersion, comprising the steps of - providing a hemicellulose, - providing organic acids or their anhydrides, - grafting the hemicellulose with the organic acids or their anhydrides by esterification reaction to obtain a hemicellulose-based surfactant, and - mixing the hemicellulose-based surfactant with an extract comprising suberin.
  13. 13. The method according to claim 12, comprising providing isolated hemicellulose, preferably obtained by extraction, membrane filtration, hydrolysis, biosynthesis routes or by the combination thereof.
  14. 14. The method according to claim 12 or 13, comprising providing hemicellulose in dissolved form, preferably dissolved in an organic solvent, in particular in dimethyl sulfoxide (DMSO).
  15. 15. The method according to any of claims 12 to 14, comprising providing the organic acids or their anhydrides dissolved in an organic solvent, such as tetrahydrofuran (THF), dimethyl sulfoxide (DMSO) or a mixture thereof.
  16. 16. The method according to any of claims 12 to 15, comprising providing the organic acids or their anhydrides dissolved in DMSO, preferably the organic acids or their anhydrides are dissolved in DMSO at a temperature of at least 40 °C, more preferably at a temperature of at least 60 °C, such as at least 65 °C, at atmospheric pressure.
  17. 17. The method according to any of claims 12 to 16, comprising activating the organic acids or their anhydrides before the grafting, preferably the organic acids or their anhydrides are activated with carbonyldiimidazole.
  18. 18. The method according to any of claim 12 to 17, wherein the grafting, i.e. the esterification reaction, is carried out in an organic solvent medium, preferably the organic solvent medium comprising at least DMSO and optionally THF.
  19. 19. The method according to any of claim 12 to 18, wherein the grafting, i.e. esterification reaction, is carried out at a temperature of at least 40 °C, especially at a temperature of at least 60 °C, in atmospheric pressure, preferably in an inert atmosphere.
  20. 20. The method according to any of claims 14 to 19, wherein the organic solvent or solvents are removed from the dispersion by any known method, such as evaporation or distillation, before mixing the hemicellulose-based surfactant with suberin.

Description

AN AQUEOUS DISPERSION FOR BINDING AND COATING APPLICATIONS FIELD [0001] The present invention relates to an aqueous dispersion, and a film thereof. In particular, the present invention concerns a novel aqueous dispersion comprising suberin and a hemicellulose-based dispersant, especially a hemicellulose grafted with organic acids. [0002] The present invention also concerns a method of producing such aqueous dispersion and its use for binding and coating applications. BACKGROUND [0003] Paper and paperboard are renewable packaging materials but they do not as such have the required barrier properties to provide protection for example against moisture, oxygen, volatile aroma, grease and oil, as well as impact of light. At present, the required barrier properties are achieved especially by extrusion plastics (e.g. polyethylene), aluminium, and/or fluorochemicals, resulting in poor end-product recyclability and increasing safety concerns in food packaging materials. Typically, such barriers used are multilayer structures. [0004] Also latexes are commonly used as coating materials. Latexes (elastomers) are soft amorphous polymers, which are commonly formulated as water-based dispersions (latexes) and used in numerous products, e.g., converted paper, packaging materials, coatings, textiles and car tyres. However, the commercial products are mainly oil-based, such as styrene-butadiene, styrene-acrylate and polyvinyl-acetate copolymers. [0005] Currently, fossil fuel-based polymer materials for coating applications put a great threaten to environment and human’s health. Thus, there is a pressing need for alternative bio-based polymer materials to replace the source of oil-based materials. [0006] For example, suberin is a complex and wax-like biopolymer that consists of long-chain fatty acids and glycerol. In particular, suberin is a mixture of hydrophobic and lipophilic biopolymers and is one of major components of outer cell walls of certain plant tissues, such as cork and bark, and can be derived from waste generated by agricultural industries. Suberin is known to provide barrier properties in plants due to its high hydrophobicity, making it a promising material for use in barrier coatings on fibre-based packaging. However, such use has not been yet implemented. [0007] However, there is a need to improve the functional properties of biopolymers for more demanding packaging applications. In particular, there is a clear need for new thermoplastic bio-based elastomers to replace the petroleum-derived synthetic polymers which are the main ones currently in use. SUMMARY OF THE INVENTION [0008] It is an aim of the present invention to reduce or even completely to eliminate the above-mentioned problems of oil-based raw material use encountered in the art. [0009] This invention provides an aqueous dispersion comprising suberin and a hemicellulose-based dispersant. The hemicellulose-based dispersant is in particular hemicellulose grafted with organic acids or their anhydrides. By mixing such hemicellulose derivative, i.e. modified hemicellulose, with suberin, an aqueous dispersion can be provided which is suitable for various end-use applications. Thus, it has been surprisingly found in the present invention that combination of the hemicellulose derivative and suberin provides improved barrier and binding properties. [0010] The aqueous dispersion of the present invention finds uses in the paper, paperboard and packaging industry as well as broader in coating and surface treatment products. [0011] According to a first aspect of the present invention, there is provided an aqueous dispersion comprising an extract comprising suberin and a dispersant comprising hemicellulose grafted with organic acids or their anhydrides. [0012] According to a second aspect of the present invention, there is provided a method of manufacturing an aqueous dispersion comprising an extract comprising suberin and a dispersant comprising hemicellulose grafted with organic acids or their anhydrides. The method comprises the steps of providing a hemicellulose, providing organic acids or their anhydrides, grafting the hemicellulose with the organic acids or their anhydrides to obtain a hemicellulose-based dispersant, and mixing the hemicellulose-based dispersant with an extract comprising suberin. [0013] According to a third aspect of the present invention, there is provided a film formed by the aqueous dispersion described above or by the method described above. [0014] According to a fourth aspect of the present invention there is provided uses for such aqueous dispersion and film. [0015] More specifically the present invention is characterized by what is stated in the independent claims. Some specific embodiments are defined in the dependent claims. [0016] Thus, the present invention is at least partly based on the idea that hemicellulose derivative -based dispersant, in particular surfactant, is used to stabilize suberin fatty acids into an aqueou