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EP-4501564-B1 - HEMP-BASED WOOD

EP4501564B1EP 4501564 B1EP4501564 B1EP 4501564B1EP-4501564-B1

Inventors

  • NOPENS, INGMAR
  • VERSTRAETE, FREDERIK
  • CORDEEL, Filip

Dates

Publication Date
20260513
Application Date
20240712

Claims (12)

  1. Hemp-based wood panel, wherein the panel extends along mutually orthogonal x and y axes, and has a thickness along a z-axis orthogonal to the x and y axes, including: a. processed hemp stalks comprising hemp shives and hemp fibers; b. a binder for joining the hemp stalks into a solid form; wherein the processed hemp stalks are oriented along their length substantially at least quasi-isotropically, and optionally isotropically, wherein the processed hemp stalks extend isotropically oriented in the plane defined by the x-axis and y-axis, preferably wherein the processed hemp stalks extend anisotropically oriented in the plane defined by the x-axis and z-axis, and extend anisotropically oriented in the plane defined by the y-axis and z-axis; wherein the processed hemp stalks constitute a weight percentage of at least 70% of the panel, and wherein the binder constitutes a weight percentage of at least 5% of the panel and at most 20% of the panel, wherein the length of at least 75% of the hemp shives is between 1.0 and 5.0 cm, and wherein the length of at least 50% of the hemp fibres is between 5.0 and 50.0 cm.
  2. Hemp-based wood panel according to the preceding claim 1, wherein the processed hemp stems are a mixture of hemp shives and hemp fibers, in a weight ratio between 3:2 and 4:1, preferably between 2:1 and 3:1.
  3. Hemp-based wood panel according to the preceding claim 1, wherein the processed hemp stalks are a mixture of hemp shives and hemp fibers in a weight ratio between 1:5 and 2:1, preferably between 1:4 and 1:1, further preferably between 1:3 and 9:11, and still further preferably between 3:7 and 2:3.
  4. Hemp-based wood panel according to the preceding claim 1, wherein the processed hemp stalks are a mixture of hemp shives and hemp fibers in a weight ratio between 4:1 and 20:1, preferably between 6:1 and 15:1, further preferably between 7:1 and 12:1.
  5. Hemp-based wood panel according to any of the preceding claims 1 to 4, wherein the processed hemp stalks are unretted.
  6. Hemp-based wood panel according to any of the preceding claims 1 to 5, wherein the processed hemp shives have a length distribution with at least 40%, preferably 50%, below 1.0 cm, and at least 60% below 2.0 cm.
  7. Hemp-based wood panel according to any of the preceding claims 1 to 6, wherein the binder is a bio-based binder, preferably a bio-based resin binder, and further preferably comprising one or more of: soy-based resin binder, castor oil-based resin binder, linseed oil-based resin binder, lignin-based resin binder, palm oil-based resin binder, bioepoxy-based resin binder, bio-based polyester, furan humines, furan resin, bio-based polyethylene, potato starch binder, pMDI, i.e. MDI or polymeric diphenylmethane diisocyanate binder.
  8. Hemp-based wood panel according to any one of the preceding claims 1 to 7, wherein the panel further comprises a granular material having a maximum diameter of 2.5 mm, preferably of 1.0 mm, further preferably of 500 µm, even further preferably of 250 µm, and most preferably of 100 µm.
  9. Hemp-based wood panel according to any of the preceding claims 1 to 8, wherein the panel further comprises a granular material having a minimum diameter of 1 µm, preferably of 10 µm, further preferred of 25 µm, and still further preferred of 50 µm.
  10. Hemp-based wood panel according to any of the preceding claims 1 to 9, wherein the panel further comprises a plurality of glass fibers, having a minimum length of 2.5 cm, preferably 5.0 cm.
  11. Hemp-based wood panel according to any one of the preceding claims 1 to 10, wherein at least 50%, preferably at least 75%, further preferably at least 85%, of the hemp fibers have a length of at most 20.0 cm, preferably at most 15.0 cm and further preferably at most 10.0 cm.
  12. Hemp-based wood panel according to any of the preceding claims 1 to 11, wherein at least 60%, preferably at least 75%, of the hemp shives have a length of at most 5 cm, preferably at most 4 cm.

Description

TECHNICAL FIELD The invention relates to hemp products. More specifically, the manufactured hemp products described herein may include hemp (composite) panels, blocks, beams, boards, flooring, furniture, building materials and other wood products. STATE OF THE ART Today's increasing demand for wood products, combined with rampant deforestation, has resulted in a scarce supply of timber resources. Many species of majestic rainforest trees are threatened or on the verge of extinction. In addition to a reduced supply of trees, many trees traditionally sought after for their timber take many years to reach maturity. Even if these trees are replanted, it will take many years to replenish the supply. This scarcity of natural wood may be particularly noticeable in industries that depend on the specific aesthetic and structural properties of natural wood, such as wood flooring, furniture, building materials or other wood industries. Alternatives to natural wood may include plywood, chipboard and the like. However, many of these alternatives are derived from natural wood, but lack the visual or technical properties of natural wood. Moreover, they may not solve the problem of finding and maintaining a sustainable supply of raw material for the future. Hemp-based materials, unlike traditional wood sources, offer the advantage of a very fast life cycle of the annual hemp plant, which allows for multiple harvests per year, generating multiple yields per unit area. Moreover, hemp also absorbs many unwanted substances in soil, so planting hemp also serves as soil remediation. Finally, hemp also has excellent mechanical characteristics in terms of strength, ductility, workability, as well as insulation value. CN108656300A discloses a hemp stem core green ecological board and a manufacturing method thereof. SUMMARY OF THE INVENTION In a first aspect, the invention relates to a hemp-based wooden panel as defined in claim 1, wherein the panel extends along mutually orthogonal x- and y-axes, and has a thickness along a z-axis orthogonal to the x- and y-axes, the panel comprising processed hemp stalks, and a binder for joining the hemp stalks into a solid form. Thereby, the processed hemp stalks are substantially quasi-isotropically oriented along the length thereof, and the processed hemp stalks make up a weight percentage of at least 70% of the panel, with the binder making up a weight percentage of at least 5% of the panel and at most 20% of the panel. In a second aspect which is not part of the claimed invention, the disclosure relates to a process for manufacturing a hemp-based wooden panel, comprising the following steps: a. reducing hemp stalks in length;b. mixing the reduced hemp stalks with a binder into a homogeneous mixture in a mould, providing the binder with a weight ratio to the reduced hemp stalks between 0.05 and 0.30, preferably between 0.1 and 0.25;c. compressing the homogeneous mixture in the mould at a pressure of preferably at least 10 bar, further preferably at least 20 bar;d. heating the compressed mixture to a minimum core temperature in the mixture of at least 120°C, preferably at least 150°C, and maintaining the minimum core temperature for a predetermined time of at least 1 minute, preferably at least 5 minutes;e. recompressing the heated mixture at a pressure, preferably of at least 10 bar, further preferably at least 20 bar;f. cooling the recompressed mixture to a temperature below 50°C, preferably below 35°C. In a further aspect, the invention relates to it being a hemp-based wooden building material with the same characteristics as the wooden panel. The dimensions, and in particular the thickness, can be varied according to the application. DETAILED DESCRIPTION Unless otherwise defined, all terms used in the description of the invention, including technical and scientific terms, have the meaning as generally understood by those skilled in the technical field of the invention. In a first aspect, the invention relates to a hemp-based wooden panel, wherein the panel extends along mutually orthogonal x- and y-axes, and has a thickness along a z-axis orthogonal to the x- and y-axes, and the panel comprising processed hemp stalks and a binder for joining the hemp stalks to a solid form. Herein, the processed hemp stalks are oriented along the length substantially at least quasi-isotropic (and optionally fully isotropic, although preferably a version that is not fully isotropic, as further described), wherein the processed hemp stalks extend isotropically oriented in the plane defined by the x-axis and y-axis, preferably wherein the processed hemp stalks extend anisotropically oriented in the plane defined by the x-axis and z-axis, and extend anisotropically oriented in the plane defined by the y-axis and z-axis, and the processed hemp stalks make up a weight percentage of at least 70% of the panel, wherein the binder makes up a weight percentage of at least 5% of the panel and at most 20% of the panel.