Biodegradable acoustic damping material and method for producing the same

Abstract

A biodegradable sound-absorbing acoustic damping material and a method for producing the same are provided. The material comprises a mixture of dried seaweed powder, fine cellulose fiber raw materials, and water. The preparation of the material involves mixing all the components into a homogeneous paste, shaping the paste, and then dehydrating it to obtain a solid paste.

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 461499, filed on April 24, 2023, entitled "ACOUSTIC ATTENUATING MATERIAL AND METHOD OF MAKING SAME". The entire content thereof is incorporated herein by reference.

[0002] The present disclosure relates to acoustic attenuating materials and methods of making the same, where the acoustic attenuating materials are completely recyclable and biodegradable.

Background Art

[0003] The production and life cycle of most current construction materials contribute to environmental degradation and climate change. According to the 2023 International Energy Agency's Buildings Report, 13% of the world's annual carbon dioxide emissions are attributable to construction materials for buildings and infrastructure. Furthermore, many construction materials are derived from non-renewable resources such as minerals, metals, and fossil fuels, and the extraction of these resources often involves environmentally harmful practices such as deforestation, habitat destruction, and ecosystem disruption. Construction and demolition activities generate large amounts of waste, much of which is non-biodegradable and remains in landfill sites for thousands of years.

[0004] Acoustic attenuating materials are widely used in the environments of many indoor buildings, such as restaurants, classrooms, office spaces, concert halls, etc. Due to the nature of acoustic attenuating materials, soft and porous acoustic panels are created to absorb sound and confine it within the material.

[0005] Currently, many acoustic damping panels exist on the market, but most are made from environmentally degrading materials such as mineral cotton, fiberglass, and polyester foam. For example, mineral fiber panels, like many construction materials, have adverse environmental impacts, mainly due to their manufacturing process and disposal after the end of their service life. Mineral fiber acoustic panels are typically made from mineral cotton, which is produced by melting minerals such as rock or slag at high temperatures. The production of mineral cotton requires a considerable amount of energy input, particularly in the melting and fiberization processes, and contributes to greenhouse gas emissions and environmental degradation. The raw materials used in mineral fiber acoustic panels (such as rock or slag) are often extracted through mining or quarrying operations. These extraction activities can result in habitat destruction, ecosystem disruption, soil erosion, and water pollution, especially if not carried out in a sustainable manner. Some mineral fiber acoustic panels may contain chemical additives or binders to improve performance or fire resistance. These additives may contain formaldehyde-based resins or other volatile organic compounds (VOCs), which can release harmful pollutants into the indoor environment, posing health risks to residents and contributing to indoor air pollution. Mineral fiber acoustic panels are typically not biodegradable, meaning they do not easily decompose or degrade in the environment. Disposal of these panels at the end of their lifecycle can contribute to waste accumulation in landfills, creating pollution that lasts for thousands of years, occupying valuable space, and potentially releasing harmful substances into the surrounding environment.

[0006] Among the few natural acoustic damping materials, wood and cork, among other organic materials, have very long harvesting cycles—about 9 years for cork and over 20 years for wood—and their harvesting is often destructive to their ecosystems.

[0007] Therefore, there is a need for low-cost, fully renewable, and biodegradable sound-absorbing materials made by combining fast-growing organic matter with recycled materials.

[0008] Seaweed is known to be one of the fastest-growing organisms. Because seaweed performs photosynthesis, absorbing carbon dioxide (CO2) and releasing oxygen, when seaweed is used as a material, it can be a form of carbon storage and consequently a carbon sink.

[0009] Given the rapid growth rate of seaweed, its ability to function as a natural binder, its potential for sustainable aquaculture, and its ability to capture and store carbon, the seaweed-based acoustic absorption material described in this patent is a truly environmentally friendly alternative to synthetic and natural acoustic damping materials currently on the market.

[0010] While several patents and scientific methods exist for using seaweed in bioplastics, aerogels, and construction materials, none of them utilize processes similar to those described in this patent, such as combining seaweed with paper to produce building materials.

[0011] Embodiments of the present disclosure will be described only as examples with reference to the accompanying drawings. [Brief explanation of the drawing]

[0012] [Figure 1] This is a flowchart of a method for producing an acoustically damping material according to an exemplary embodiment of the present disclosure. [Figure 2] Examples of acoustic panels with surface textures and perforations are shown. [Figure 3] Examples of acoustic panels with surface textures and perforations are shown. [Figure 4] This graph compares the sound absorption rates of commercially available Radar acoustic ceiling panels (made from mineral fibers) and the two acoustic panel examples described here. The X-axis represents sound frequency, and the Y-axis represents the sound absorption coefficient. [Figure 5] This diagram illustrates how sound propagates through partitions such as walls. Solid arrows represent incident sound waves, wavy arrows represent absorbed sound waves, and dashed arrows represent reflected or transmitted sound waves.

[0013] Similar reference numerals used in different diagrams indicate similar components. [Modes for carrying out the invention]

[0014] In general terms, the non-limiting exemplary embodiments of this disclosure provide acoustic damping materials and methods for producing the same, which are fully regenerative and biodegradable. Acoustic damping has two aspects: sound insulation and sound absorption, which are illustrated in Figure 5. Sound insulation is designed to prevent sound from entering or leaving a space by blocking the transmission of sound using dense, heavy materials, and is ideal for environments where sound leakage is a concern. Sound absorption, on the other hand, aims to improve the acoustic quality within a space by reducing reverberation and echoes, using lightweight, porous materials to contain and convert sound waves. While sound insulation focuses on blocking sound, sound absorption improves the internal acoustic environment, and each serves a different purpose in noise suppression. When used herein, the acoustic damping materials provided herein have sound-absorbing properties. In some embodiments, the acoustic damping materials provided herein also have sound-insulating properties in addition to sound-absorbing properties.

[0015] Acoustic damping materials can be poured into molds in desired shapes and sizes, and are porous and lightweight. To possess sound-absorbing properties, acoustic damping materials need to have sufficient porosity and lightness. At the same time, for use as building materials (such as panels), acoustic damping materials need to have sufficient structural integrity. Furthermore, acoustic damping materials can be rehydrated multiple times and poured back into molds without compromising their material properties, and are compostable.

[0016] The acoustic damping material is made from three main components: seaweed such as brown algae, paper such as used, low-quality paper recovered from recycling boxes, and water. The resulting acoustic damping material absorbs sound at a level similar to materials currently used to manufacture building acoustic panels, such as mineral fibers, polyester foam, cork, and thick fabrics. The acoustic damping material disclosed herein has a noise reduction coefficient in the range of 0.5 to 0.7, depending on variables such as surface texture, cracks, and thickness.

[0017] The term "seaweed" encompasses a range of multicellular marine algae visible to the naked eye. Examples of seaweed genera include Caulerpa (green algae), Fucus (brown algae), Gracilaria (red algae), Laminaria (brown algae), Macrocystis (brown algae), Monostroma (green algae), Porphyra (red algae), and Sargassum (brown algae). In some embodiments, acoustic damping materials are made from brown seaweed. Examples of brown seaweed that may be used to make acoustic damping materials include Fucus distichus (rockweed), Nereocystis (bull kelp), Sargassum, and Saccharina latissimi (sugar kelp). Seaweed is known to be one of the fastest-growing organisms. Large brown macroalgae, such as kelp, in particular, have especially rapid growth rates and are ideal seaweed sources for producing materials.

[0018] Construction materials and composites generally consist of a binder and aggregates. In the case of the disclosed acoustic damping material, seaweed is the binder and paper is the aggregate. The inventors have found that seaweed (particularly in the form of powdered seaweed) and paper when mixed with hydrothermal water are ideal binders and aggregates for producing an acoustic damping material that has sound-absorbing properties, is sufficiently lightweight, and yet possesses sufficient structural integrity to form a building material. The acoustic damping properties and performance of the disclosed acoustic damping material are similar to those of commonly used mineral fiber ceiling acoustic panels, with the additional advantages of being fully biodegradable and a sustainable source.

[0019] Substances capable of forming gels (e.g., alginates, agar, or gelatin raw materials) can be used to form natural acoustic damping materials. In preferred embodiments, powdered seaweed is used, which in its powdered form results in a more efficient binder. In one embodiment, flaked seaweed is used. The cell wall of brown seaweed is composed of 1 part fucan, 1 part cellulose, and 3 parts alginate. When the alginate component of the seaweed is mixed with hot water, a gel-like binder is formed that holds the acoustic material together, while the other components of the seaweed contribute to the structural integrity of the acoustic damping material.

[0020] As used herein, the term “paper” refers to any material consisting of fine cellulose fibers. In some embodiments, the disclosed acoustic damping materials are made from seaweed powder, raw materials for fine cellulose fibers (e.g., paper or wood chips), and water. Ideally, paper with minimal additives or coatings (e.g., paper without plastic or wax components) is preferred. Fine cellulose fibers have a fiber width in the range of micrometers, i.e., from a few micrometers to several hundred micrometers. The aspect ratio (ratio of fiber length to diameter) affects the ability of cellulose fibers to bond with other fibers. A higher aspect ratio (longer fiber length and smaller diameter) results in a greater ability of fibers to bond with each other, creating a stronger material. The ideal aspect ratio for cellulose fibers for making the disclosed acoustic damping materials is a length in the range of a few millimeters and a diameter in the range of a few microns. Examples of other materials or raw materials containing fine cellulose fibers include finely ground wood chips. While finely ground wood chips can be used to create the disclosed acoustically damping materials, these fibers often have a low aspect ratio and may require additional binders such as glycerol to increase material strength.

[0021] Referring to Figure 1, a flowchart of a method for producing an acoustically attenuating material according to an exemplary embodiment of the present disclosure is shown. The steps of Method 100 are shown by blocks 102 to 114.

[0022] Process 100 begins with block 102, where the fresh seaweed is dried and dehydrated. Several drying and dehydration methods are possible (such as air drying, oven drying, and freeze drying). The goal is to dry the seaweed thoroughly so that it can be crushed into a fine powder. One example of the process is to air dry the seaweed in the shade for 3 to 7 days, and then in block 104, dehydrate the dried seaweed at 250 degrees Fahrenheit for 3 hours, or dehydrate it until it is crisp enough to be crushed into a powder. The dehydration time and temperature depend on the type of seaweed and its moisture content.

[0023] In block 106, the baked seaweed is crushed into powder, and in block 108, the powdered seaweed is mixed with shredded low-quality paper such as the paper collected from the waste paper recycling bin and boiling water. It should be understood that other types of paper such as recycled paper may also be used. The mixture is at least 3 parts water, or at least 4 parts water, or at least 5 parts water per 1 part of the dry components, and the dry components are seaweed powder and paper. The mixture is at most 18 parts water per 1 part of the dry components. In one exemplary embodiment, 3 parts water are mixed together per 1 part of the dry components. The ratios provided herein are calculated by weight ratio. Regarding the dry components, in some embodiments, the ratio of seaweed powder to paper is 3:1, 2:1, 1:1, 1:2, 1:3. The mixture is left to mix until it becomes a homogeneous paste. It should be understood that many different ratios of seaweed, paper, and water can be used, and all will yield similar results. In one embodiment, 1 part seaweed powder, 2 parts paper, and 16 parts boiling water are mixed together. In another embodiment, 2 parts seaweed powder, 1 part paper, and 10 parts boiling water are mixed together. In a preferred embodiment, 1 part seaweed powder, 1 part shredded paper, and 7 parts hot water are mixed together.

[0024] Optionally, in block 109, an additive may be added to the homogeneous paste from block 108. Alternatively, the additive may be mixed with the powdered seaweed, shredded low-quality paper, and boiling water in block 108. In a preferred embodiment, biodegradable additives such as colorants and fragrances are added to change the appearance of the material. For example, natural fragrances such as ginger or lavender or cedar may be added to neutralize the odor generated from the seaweed. In one example, in block 108, 1 part seaweed powder, 1 part shredded paper, 7 parts hot water, and 0.2 parts ginger are mixed together by weight.

[0025] In some embodiments, biodegradable additives such as clay, crushed eggshells, crushed seashells, and other substances rich in calcium / calcium carbonate are added to increase the strength, density, and sound insulation quality of the material. In particular, the additive serving as a calcium source provides structural strength and integrity to the acoustic attenuation material and increases the acoustic shielding properties.

[0026] To increase the sound absorption of the material, in block 109, a biodegradable pore-forming agent may be added to the paste. Examples include baking powder, baking soda, or Epsom salts. For example, 0.3 parts of baking powder are added per 1 part of seaweed powder. In some embodiments, baking powder in a weight ratio of about 1 - 10%, preferably about 3 - 7%, more preferably about 5% is added to the mixture. The pore-forming agent enables the paste to expand and increases the porosity of the final acoustic attenuation material.

[0027] In some embodiments, one or more additional binders are added to the paste as additives. Examples of additional binders include glycerol, starch, gelatin, gum arabic, and chitosan for increasing the strength and flexibility of the acoustic attenuation material.

[0028] Next, in block 110, the paste is foamed and applied into a mold of the desired shape and size, left to stand for about 3 minutes, and then in block 112, the paste is removed from the mold and dehydrated in an oven at 250°F. It should be understood that the dehydration time varies depending on the thickness of the mold used and the required strength and flexibility of the acoustic attenuation material. It should also be understood that there are many processes such as a low-temperature oven, dehydrator, and freeze-drying for dehydrating the paste. In some embodiments, the molded paste is dehydrated to about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5% of the original moisture content by weight. In a preferred embodiment, 100% of the original moisture content is removed through dehydration.

[0029] In an alternative embodiment, the paste is molded to the desired shape and size, for example by hand, without the use of a mold, and then dehydrated. In yet another alternative embodiment, the paste is applied in a foamy manner into a mold and at least partially dehydrated within the mold before the dried paste is removed from the mold.

[0030] In some embodiments, the mold has a depth ranging from 1 cm to 5 cm. After dewatering, the acoustic damping material has a thickness of about 0.5 cm to 4 cm, more preferably about 1.5 cm to 2.5 cm, and most preferably about 2 cm.

[0031] Finally, in block 114, the dehydrated acoustic damping material is polished to obtain a precise shape and flat edges. This step may include post-processing substeps such as laser or mechanical cutting, laser etching, perforation, and / or sewing.

[0032] Please understand that various times and temperatures can vary depending on the amount and type of materials used, the type of equipment used, and other conditions such as humidity.

[0033] The resulting acoustic damping material is capable of absorbing sound, with a sound absorption capacity of approximately 60-120 kg / m, more preferably approximately 80-110 kg / m. 3 The range is most preferably about 90 kg / m 3 The present inventors have found that the acoustic damping material having the density described herein provides sufficient lightness or porosity to effectively absorb sound, while also having sufficient integrity to be fabricated into tiles or panels.

[0034] Surface texture To further improve the sound absorption properties of the acoustic damping materials disclosed herein, surface textures may be introduced. For example, in block 110, the paste is applied in a foamy manner to a mold having a textured wall surface that imparts texture to the surface of the acoustic damping material. Alternatively, a textured mold plate may be pressed against the molded paste to impart texture to the surface.

[0035] As shown in Figures 2 and 3, examples of acoustically attenuating materials having surface texture and surface pores are illustrated. Examples of surface textures include rough, porous textures, wavy textures with alternating peaks and valleys, or other surface textures. In some embodiments, surface pores are created mechanically. For example, surface pores are created by needling, by introducing protrusions into the wall of a mold, or by pressing a mold plate with protrusions against a molded paste. The surface pores have a diameter of 2 mm or less, preferably 1 mm or less.

[0036] The sound attenuation properties of acoustically attenuating materials with surface textures and perforations were tested in comparison to commercially available acoustic ceiling panels, as shown in Figure 4. The tests were conducted using impedance tubing and AED's AcoustiStudio software. Impedance tubing is an acoustic device that uses the two-microphone method, a standard method for measuring the acoustic absorption coefficient of materials in accordance with ASTM E1050-19. At frequencies above approximately 700 Hz, the acoustically attenuating materials exhibit comparable sound absorption to commercially available acoustic panels. The sound absorption of the acoustically attenuating materials also increases at frequencies below 700 Hz, and this absorption is typically associated with sound insulation. Therefore, acoustically attenuating materials also provide sound absorption and partial sound insulation.

[0037] Flame retardant The acoustic damping materials disclosed herein exhibit flame-retardant properties because they carbonize very slowly without generating an ignition source.

[0038] It should be understood that the flame retardancy of acoustic damping materials can be adjusted by varying the salt content of the seaweed, the compressive force applied to the materials used, the ratio of paper, and / or by adding biodegradable flame retardants to the mixture.

[0039] Lifecycle Acoustic damping materials do not imply permanent durability like their mineral fiber-based counterparts. They have a fully circular, cyclical lifecycle. If a panel cracks or a different shape is needed, it can be removed, rehydrated in a mixer, and poured back into the mold to create new panels repeatedly. When panels are no longer needed, they can be composted and used as fertilizer. Seaweed is used as fertilizer worldwide because it is rich in cytokinins, nutrients that promote cell division and help plants absorb nutrients from the soil.

[0040] The cultivation of seaweed, specifically sugar kelp, a type of brown seaweed that grows naturally along the coast of British Columbia, Canada, is simple and beneficial to the ecosystem. Sugar kelp is seeded onto cotton ropes, which are then stretched along the surface of the sea on soft, sandy seabeds in areas where seaweed has not previously grown. The kelp is then allowed to grow during the winter and harvested in early summer. Sugar kelp requires no fertilizers or pesticides to grow and does not disrupt any ecosystem. The cultivation area simply needs to be located in an area with high salinity and nutrients. Because seaweed performs photosynthesis, it removes CO2 from the ocean, produces oxygen, and filters toxins from the ocean. Furthermore, sugar kelp sheds 50% of its mass during its growth process, meaning that even after harvesting, it still provides an equivalent amount of nutrients to the ecosystem. Furthermore, sugar kelp provides a nurturing habitat for species such as herring to lay their eggs in the spring before the seaweed is harvested. Economically speaking, sugar kelp farming is inexpensive and requires little initial investment. From a broader perspective, one kilogram of dried seaweed is produced per meter of rope in a sugar kelp farm. The other component, paper, is recovered from waste paper bins and does not end up in landfills or highly intensive water and energy recycling processes.

[0041] Compared to wood and other natural acoustic materials such as cork, sugar kelp is one of the fastest-growing organisms on Earth, with a growth cycle of one year. In comparison, cork harvesting takes more than nine years, and wood takes more than 20 years. Acoustic damping materials are not only sustainable but also regenerative, meaning they are beneficial to the ecosystems they are part of.

[0042] Educational tools Acoustic damping materials can also be used in schools as an educational tool to share different perspectives on material properties while respecting the environment. Students can be taught how to create acoustic damping materials step by step, starting with learning about harvesting seaweed and the ecosystems it belongs to, and eventually progressing to creating acoustic panels that can be used in the classroom and ultimately composted in the garden.

[0043] insulation The acoustic damping material may also be molded as a panel having a thickness and size that allows it to be used as a thermal insulator.

[0044] While this disclosure has been described using certain non-limiting exemplary embodiments and examples thereof, it will be apparent to those skilled in the art that modifications may be made to certain embodiments of the invention without departing from the scope of this disclosure, as claimed hereafter.

Claims

1. A method for producing an acoustically damping material capable of sound absorption, wherein the method is a) A step of mixing a mixture consisting only of natural and biodegradable materials, consisting of dried seaweed powder, fine cellulose fiber raw materials, and water, to form a homogeneous paste, b) The step of shaping the paste into a desired shape and size, c) A step of removing water from the paste and forming a solid paste to produce the sound-damping material, wherein the sound-damping material is biodegradable, Methods that include...

2. The method according to claim 1, wherein molding the paste into a desired shape and size includes applying the paste in a foamy manner into a mold of the desired shape and size, or extruding it.

3. The aforementioned acoustic damping material has an acoustic damping capacity of approximately 60 to 120 kg / m³. ３ The method according to claim 1, wherein the density is 0.5 cm and the minimum thickness is 0.5 cm.

4. The method according to claim 2, wherein the mold has a depth in the range of about 1 cm to 5 cm.

5. The method according to claim 1, wherein the sound-damping material has a thickness in the range of about 0.5 cm to 4 cm.

6. The method according to claim 1, wherein the sound-damping material has a thickness in the range of about 1.5 cm to 2.5 cm.

7. The method according to claim 1, wherein the sound-damping material has a thickness in the range of about 2 cm.

8. The method according to claim 1, further comprising drying seaweed and crushing the dried seaweed to obtain dried seaweed powder.

9. A method for producing an acoustic damping material according to claim 1, wherein in step 1), the mixture contains at least 3 parts water by weight to 1 part dry component.

10. A method for producing an acoustic damping material according to claim 1, further comprising step d) forming the acoustic damping material into a panel by laser cutting, mechanical cutting, laser etching, perforation, or sewing.

11. The method according to claim 1, further comprising adding a pore-forming agent to the mixture in order to increase the porosity of the sound-damping material and improve its sound absorption.

12. The method according to claim 11, wherein the porosity-forming agent is one or more of baking powder, baking soda, or Epsom salt.

13. The method according to claim 12, wherein the porosity-forming agent comprises about 5% by weight of baking powder.

14. The method according to claim 1, further comprising mixing the mixture comprising the seaweed powder, shredded paper, and water with a biodegradable additive to form the homogeneous paste.

15. The method according to claim 14, wherein the additive is one or more of clay, calcium carbonate, eggshell powder, and seashell powder to increase the strength, density, and sound insulation quality of the sound-damping material.

16. The method according to claim 14, wherein the additive is a binder comprising one or more of glycerol, starch, gelatin, gum arabic, and chitosan for increasing the strength and flexibility of the sound-damping material.

17. The method according to claim 2, wherein the mold includes a textured wall formwork that imparts a surface texture to the sound-damping material.

18. The method according to claim 1, further comprising adding surface pores to the sound-damping material.

19. An acoustic damping material capable of sound absorption, comprising natural and biodegradable input materials for making a paste, wherein the solid paste comprises a homogeneous paste made from a mixture of seaweed powder, fine cellulose fibers, and water, and the density of the acoustic damping material is approximately 60 to 120 kg / m³. ３ The sound-damping material is a biodegradable sound-damping material.

20. The acoustic damping material according to claim 19, wherein the mixture contains at least 3 parts of water by weight to 1 part of the dry component.

21. The acoustic damping material according to claim 19, which is formed into a panel by laser cutting, mechanical cutting, laser etching, perforation, or sewing.

22. The acoustic damping material according to claim 19, comprising a pore-forming agent.

23. The sound-damping material according to claim 22, wherein the pore-forming agent is one or more of baking powder, baking soda, or Epsom salt.

24. The sound-damping material according to claim 19, comprising a biodegradable additive, wherein the additive is one or more of clay, calcium carbonate, powdered eggshell, powdered seashell, dye, flame retardant, and ginger.

25. The acoustic damping material according to claim 19, comprising a surface texture.

26. The acoustic damping material according to claim 19, comprising a plurality of surface pores with a diameter of 1 mm or less.

27. The sound-damping material according to claim 19 for use as tiles or panels for ceilings, walls, or floors.

28. The acoustic damping material according to claim 19 for use as an insulating material.

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