Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/162—Selection of materials
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/162—Selection of materials
  • G10K11/165—Particles in a matrix

Definitions

• the present invention lies in the technical field of acoustic room design and provides an acoustic panel comprising a composite material made of cereal husks and gluten.
• a method for producing an acoustic panel according to the invention and the use of such a panel for sound absorption and/or sound interruption are also provided.
• Sound absorbers or acoustic panels are typically made of foam, various polymers, felt, or mineral wool.
• sustainable materials preferably made from sustainable raw materials.
• panels made from mushroom mycelium or hemp are used for this purpose.
• Such a material is, for example, fiber-reinforced plastics with biological filling materials, some of which are not based on petrochemical materials such as plastic, but are combined with biological materials such as rice husks, rice husks, sisal, etc., as in the EP 1 338 405 B1 described.
• the materials described can be used in a variety of ways, e.g. as windows and doors due to their good weather resistance.
• German patent application DE 10 2018 111 210 A1 This discloses a material consisting of cereal husks and an organic polymer, which is processed into a polymer-husk composite material.
• the material can be used as doors, windows, paneling, or insulation.
• the material can be coated with a fire retardant, thus reducing flammability.
• a material based on cereal husks as a side stream of the agricultural industry is included in the European application EP 3 865 422 A1
• This application discloses a molded packaging component based on cereal husks for packaging, for example, fragile items for shipping.
• the material is a composite of cereal husks and a plant-based binder.
• materials used as sound absorbers also be made from sustainable materials. Side streams from the food and agricultural industries are suitable as starting materials.
• the primary object of the present invention was therefore to provide a material based on renewable raw materials that can be used as a sound-absorbing material.
• FIG. 1 shows schematically the structure of an acoustic panel 1 according to the invention.
• the acoustic panel 1 comprises a composite material made of cereal husks 2 and glutin 4 and can be coated with a fire retardant 6.
• the primary object of the present invention has been achieved by providing an acoustic panel 1 comprising or consisting of a composite material of cereal husks 2 and glutin 4.
• FIG. 1 shows schematically the structure of an acoustic panel 1 according to the invention.
• the acoustic panel 1 comprises a composite material made of cereal husks 2 and glutin 4 and can be coated with a fire retardant 6.
• An acoustic panel 1 within the meaning of the present invention is a material that absorbs sound energy and converts it into heat. Acoustic panels can be used as ceiling and wall absorbers, table top panels, partition walls, and room dividers or partition walls. Acoustic panels lead to an acoustic improvement in the indoor climate.
• Grain husks 2 are the bracts in the spikelet, which is a partial inflorescence of the grass family (Poaceae). Husks fulfill the natural function of protecting the flowers of a grass, such as wheat. These are removed from the grain during threshing and are a waste product, along with the awns, seed coats, and stem parts, known as chaff in the agricultural industry.
• Glutin 4 is a mixture of denatured protein based on collagen and can be obtained by boiling collagen-containing ingredients such as bones, cartilage, skins, or fish bones. Glutin is used as a glue in the wood industry, in restorations, and in traditional handicrafts, among other applications.
• glutin 4 leads to a very good and stable bonding of the grain husks 2 among each other and thus to the stability of the acoustic panel.
• An acoustic panel 1 made of glutin 4 and grain husks 2 has the advantage that the raw materials are generated as side streams of the food industry and are therefore sustainable. It is therefore particularly preferred that the acoustic panel 1 contains no ingredients of petrochemical origin.
• the glutin 4 interacts with the grain husks 2 to produce a porous absorber material.
• the grain husks 2 are preferably evenly distributed throughout the material and are held together by the glutin 4.
• the grain husks 2 form a cavity that is essentially unfilled by the glutin 4, so that the acoustic panel 1 has a porous structure.
• the grain husks 2 exhibit essentially closed cavities. This means, in particular, that there is a completely closed and/or essentially closed cavity into which glutin 4 cannot penetrate, or can penetrate only with difficulty or to a limited extent.
• the provided acoustic panel 1 is completely biodegradable as it does not contain any petrochemical components.
• the grain husks 4 are preferably selected from the group consisting of wheat husks, rye husks, rice husks, millet husks, and spelt husks, with spelt husks being particularly preferred. Furthermore, mixtures of different grain husks 2 are preferably used. The porosity and thus the properties of the acoustic panel can be specifically influenced by the grain husks 2 used.
• Spelt husks have two husks, a small and a large husk, and therefore provide particularly good stability for the acoustic panel, which is achieved through the interlocking of the husks.
• the hollow spaces created by the spelt husks ensure particularly high porosity, which leads to high sound absorption and therefore provides a particularly preferred acoustic panel.
• the glutin 4 originates from an animal glue, preferably selected from the group consisting of bone glue, fish glue, rabbit glue, hide glue or mixtures thereof.
• An animal glue within the meaning of the present invention is a glutin glue which is obtained by boiling bones, cartilage, skins or fish bones.
• Glutin is not synonymous with gelatin. Glutin is an unpurified form and contains impurities that arise from the manufacturing process. The biggest difference, however, is the chemical structure. Glutin is obtained through a gentle manufacturing process, which results in the presence of undenatured collagen fibers in the resulting glutin glue. This results in glutin glue having strong adhesive properties, whereas gelatin consists of denatured collagen and its gelling properties are more prominent. Gelatin is particularly pure, odorless, and colorless. Glutin has a yellowish to brownish color, a strong odor, and is impure. The processing of glutin is an enormous challenge, as it less pure than gelatin. Gelatin is suitable for food use, while glutin is not due to the impurities that are advantageous in the context of the present invention.
• glutin is preferred because it requires less energy to produce, releases less CO2, and is a by-product of slaughterhouse waste.
• the composite material of the acoustic panel 1 is coated with a fire retardant 6, which is preferably selected from the group consisting of amorphous sodium, potassium, and lithium silicate, or mixtures thereof. Fire retardants are also referred to as flame retardants.
• the acoustic panel 1 preferably has a water content of between 0.5 and 25 wt.%, preferably between 1 and 20 wt.%, and particularly preferably between 5 and 20 wt.%.
• the water content is determined using a method familiar to the person skilled in the art, such as constant dryness or Karl Fischer titration.
• the acoustic panel 1 according to the present invention has the property that it can absorb and release water and thus contributes to the regulation of humidity and the room climate.
• the acoustic panel 1 preferably has a bulk density of between 100 and 450 kg/m 3 , preferably between 150 and 350 kg/m 3 and particularly preferably between 200 and 250 kg/m 3 .
• the acoustic panels according to the present invention can have different thicknesses and thus be suitable for different applications.
• a mixture of glutin (4) and water is first prepared.
• This mixture has the advantage that the viscosity of the resulting mixture after heating is particularly advantageous for further processing.
• this creates a particularly advantageous mixture together with the grain husks (2), which are added in step c).
• the water-glutin mixture from step b) ensures uniform wetting of the grain husks (2), thus resulting in a uniform bond between glutin (4) and grain husks (2), as well as ensuring the adhesion of the grain husks (2) to one another.
• the resulting acoustic panel (1) is highly stable and suitable for many applications.
• the heating in step b) is carried out at 60°C ( ⁇ 2 °C).
• Heating the water-gluten mixture produces a flowable mixture that can be poured into any desired mold (step d).
• the molds can preferably have straight or curved sections.
• the water from the water-gluten mixture evaporates, resulting in an acoustic panel 1 made of grain husks 2 and gluten 4 as a binding agent, which contains only a low residual moisture content.
• the acoustic panel 1 is dried in step d) in a drying chamber at a temperature of between 30°C and 80°C, preferably between 35°C and 70°C and preferably at a temperature of between 40°C and 60°C.
• step a) water is provided in an amount of 20 to 60 wt.%, preferably in an amount of 30 to 50 wt.% and Glutin 4 in an amount of 5 to 30 wt.%, preferably in an amount of 10 to 20 wt.%.
• the acoustic panels according to the invention can also be used as thermal insulation panels, for example to shield houses or rooms against heat loss.
• the resulting acoustic panels are coated with a water glass solution (a mixture of sodium, potassium, and lithium silicate) at a concentration of 0.6 kg/ m2 as a fire retardant.
• a water glass solution a mixture of sodium, potassium, and lithium silicate
• the panels obtained in step e) are coated on both sides with water glass using a suitable spray device.
• the resulting acoustic panel After coating with water glass, the resulting acoustic panel has building material class B1 (flame-retardant) according to DIN 4102-1.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Building Environments (AREA)

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Publications (1)

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Family Applications (1)

Country Status (2)

Citations (5)

Family Cites Families (4)

• 2024
  • 2024-03-07 DE DE102024106573.7A patent/DE102024106573A1/de active Pending
• 2025
  • 2025-02-10 EP EP25156895.2A patent/EP4614493A1/fr active Pending

Patent Citations (5)

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