Acoustic felt structures and methods of making the same

Abstract

Disclosed herein is an acoustic structure. The acoustic structure includes a substrate having a first surface opposite a second surface. The substrate includes a web of non-woven natural fibrous material and a binding composition distributed throughout the web. The binding composition includes a waterborne reactive emulsion or a thermoplastic latex. Also disclosed are methods for manufacturing acoustic structures.

Description

ACOUSTIC FELT STRUCTURES AND METHODS OF MAKING THE SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a PCT International Application that claims the benefit of U.S. Provisional Application No. 63 / 612274 filed on December 19, 2023. The disclosure of the above application is incorporated herein by reference.FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to felt structures, such as ceiling and wall panels, and more particularly to acoustic felt structures comprised of sustainable materials.BACKGROUND

[0003] Building materials, such as acoustics structures, planks, and panels for ceiling and wall systems, are designed to balance interests with respect to aesthetics, material cost, structural integrity, fire safety, acoustics, and environmental impact.

[0004] Accordingly, those skilled in the art continue research and development in the field of acoustic felt structures.SUMMARY

[0005] This summary is intended merely to introduce a simplified summary of some aspects of one or more implementations of the present disclosure. Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description below.

[0006] Applicants have discovered acoustic structures, such as wall or ceiling panels, comprised of sustainable, biodegradable materials.

[0007] In one example, the disclosed acoustic structure includes a substrate having a first surface opposite a second surface. The substrate includes a web of non-woven natural fibrous material and a binding composition distributed throughout the web. The binding composition includes a waterborne reactive emulsion or a thermoplastic latex.

[0008] In certain examples, the non-woven natural fibrous material is felt including one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool. In certain examples, the non-woven natural fibrous material includes hemp.

[0009] In certain examples, the web has basis weight ranging from about 300 gsm to about 2500 gsm. In certain examples, the web has a thickness ranging from about 5mm to about 50 mm. In certain examples, the web has a porosity ranging from about 70% to about 95%. In certain examples, the web further includes at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0010] In certain examples, the binding composition includes a cross-linking alkyd, a polyester, an acrylic or an epoxy resin. In certain examples, the binding composition includes a biobased cross-linking alkyd resin. In certain examples, the binding composition includes styrene acrylic, vinyl acrylic, or polyvinyl acetate. In certain examples, the binding composition has a glass transition temperature above 50°C. In certain examples, the binding composition further includes a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition. In certain examples, the flame retardant includes one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides. In certain examples, the flame retardant includes ammonium polyphosphate. In certain examples, the flame retardant includes aluminum trihydrate. In certain examples, the binding composition further includes one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes calcium carbonate present in an amount from about 20 wt. % to about 40 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a foaming agent present in an amount from about 0.01 wt. % to about 3 wt. %, based on the total dry weight of the composition. In certain examples, the foaming agent is a biobased foaming agent derived from sugar. In certain examples, the binding composition further includes a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0011] In certain examples, the substrate is comprised of about 85% to about 99% natural materials. In certain examples, the acoustic structure exhibits an NRC from about 0.65 to about 0.90.

[0012] Also disclosed are methods for manufacturing acoustic structures.

[0013] In one example, the method includes providing a web having a first surface opposite a second surface, the web comprised of non-woven natural fibrous material. The method further includes applying a binding composition to at least one of the first surface and the second surface, wherein the binding composition includes a waterborne reactive emulsion or a thermoplastic latex.

[0014] In certain examples, the method includes applying the binding composition to the opposing surface of the web. In certain examples, the method includes infusing the binding composition into the web. In certain examples, the method includes dipping the web into the binding composition to saturate the web and subsequently squeezing the web in the nip remove excess binding composition. In certain examples, the method includes drying the web after applying the binding composition. In certain examples, the method includes curing the web after applying the binding composition.

[0015] In certain examples, the non-woven natural fibrous material includes one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool. In certain examples, the non-woven natural fibrous material includes hemp. In certain examples, the web has basis weight ranging from about 300 gsm to about 2500 gsm. In certain examples, the web has a thickness ranging from about 5mm to about 50 mm. In certain examples, the web has a porosity ranging from about 70% to about 95%. In certain examples, the web further includes at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0016] In certain examples, the binding composition includes a cross-linking alkyd, a polyester, an acrylic or an epoxy resin. In certain examples, the binding composition includes a biobased cross-linking alkyd resin. In certain examples, the binding composition includes styrene acrylic, vinyl acrylic, or polyvinyl acetate. In certain examples, the binding composition has a glass transition temperature above 50°C. In certain examples, the binding composition further includes a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition. In certain examples, the flame retardant includes one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides. In certain examples, the flame retardant includes ammonium polyphosphate. In certain examples, the flame retardant includes aluminum trihydrate. In certain examples, the binding composition further includes one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition. In certain examples, the bindingcomposition further includes calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a foaming agent present in an amount from about 0.01 wt. % to about 3 wt. %, based on the total dry weight of the composition. In certain examples, the foaming agent is a biobased foaming agent derived from sugar. In certain examples, the binding composition further includes a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0017] In certain examples, the substrate is comprised of about 85% to about 99% natural materials. In certain examples, the acoustic structure exhibits an NRC from about 0.65 to about 0.90.

[0018] In another example, a method for manufacturing an acoustic structure includes providing a web of non-woven natural fibrous material having a first surface opposite a second surface, mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion, foaming the binder dispersion to form a foamed binder dispersion, and applying the foamed binder dispersion to at least one of the first surface and the second surface of the web.

[0019] In certain examples, the method includes applying the foamed binder dispersion to the opposing surface of the web. In certain examples, the method includes drying the web after applying the foamed binder dispersion. In certain examples, the drying is performed at a temperature below 100 °C. In certain examples, the non-woven natural fibrous material includes one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool. In certain examples, the non-woven natural fibrous material includes hemp. In certain examples, the web has basis weight ranging from about 300 gsm to about 2500 gsm. In certain examples, web has a thickness ranging from about 5mm to about 50 mm. In certain examples, the web has a porosity ranging from about 70% to about 95%. In certain examples, the web further includes at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0020] In certain examples, the binding composition includes a cross-linking alkyd, a polyester, an acrylic or an epoxy resin. In certain examples, the binding composition includes a biobased cross-linking alkyd resin. In certain examples, the binding composition includes styrene acrylic, vinyl acrylic, or polyvinyl acetate. In certain examples, the binding composition has a glass transition temperature above 50°C. In certain examples, the binding composition further includes a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition. In certain examples, the flame retardant includes one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides. In certain examples, the flame retardant includes ammonium polyphosphate. In certain examples, the flame retardant includes aluminum trihydrate. In certain examples, the binding composition further includes one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition. In certain examples, the binding composition further includes a foaming agent present in an amount from about 0.01 wt. % to about 3 wt. %, based on the total dry weight of the composition. In certain examples, the foaming agent is a biobased foaming agent derived from sugar. In certain examples, the binding composition further includes a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0021] In certain examples, the substrate is comprised of about 85% to about 99% natural materials. In certain examples, the acoustic structure exhibits an NRC from about 0.65 to about 0.90.

[0022] In another example, a method for manufacturing an acoustic structure includes carding a plurality of natural fibers, blending the plurality of natural fibers, forming the plurality of natural fibers into a mat, lapping the mat to form a web having a first surface opposed a second surface, needle punching the web, mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion, foaming the binder dispersion to form a foamedbinder dispersion, applying the foamed binder dispersion to at least one of the first surface and the second surface of the web, drying the web, and curing the web to yield an acoustic structure.

[0023] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred examples of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.DESCRIPTION OF THE DR WINGS

[0024] The detailed description of the disclosure will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the examples shown in the drawings.

[0025] Fig. 1 is a perspective view of an acoustic structure;

[0026] Fig. 2 is a front view of the acoustic structure of Fig. 1;

[0027] Fig, 3 is a side view of the acoustic structure of Fig. 1;

[0028] Fig. 4 is a perspective view of an acoustic system; and

[0029] Fig. 5 is a side view of the acoustic system of Fig. 4.DETAILED DESCRIPTION

[0030] For illustrative purposes, the principles of the present disclosure are described by referencing various examples thereof. Although certain examples of the disclosure are specifically described herein, one of ordinary skill in the art will readily recognize that the same principles are equally applicable to, and can be employed in other applications and methods. It is to be understood that the disclosure is not limited in its application to the details of any particular example shown. The terminology used herein is for the purpose of description and not to limit the disclosure, its application, or uses.

[0031] As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context dictates otherwise. The singular form of any class of the ingredients refers not only to one chemical species within that class, but also to a mixture of those chemical species. The terms “a” (or “an”), “one or more” and “at least one” may be used interchangeably herein. The terms “comprising”, “including”, “containing”, and “having” may be used interchangeably. The term “include” should be interpreted as “include, but are not limited to”. The term “including” should be interpreted as “including, but are not limited to”.

[0032] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range.

[0033] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight of the total composition. Unless otherwise specified, reference to a molecule, or to molecules, being present at a “wt. %” refers to the amount of that molecule, or molecules, present in the composition based on the total weight of the composition. Unless otherwise specified, reference to a molecule, or to molecules, being present “based on the dry weight of the composition” refers to that molecule, or molecules, being present in the composition based on the total weight of the composition in a dry state. The “dry state” refers to solvent being present in the composition at an amount less than 5.0 wt. %, less than about 3.0 wt. %, less than about 1.0 wt. %; preferably less than about 0.5 wt. %, and more preferably less than about 0.25 wt. % of the composition. For example, a composition in the dry state may refer to a composition having about 95% solids, about 98% solids, preferably about 99% solids, or more preferably about 100% solids. By contrast, unless otherwise specified, reference to a molecule, or to molecules, being present “based on the wet weight of the composition” refers to that molecule, or molecules, being present in the composition based on the total weight of the composition which includes at least 5 wt. % of solvent.

[0034] According to the present application, use of the term “about” in conjunction with a numeral value refers to a value that may be + / - 5% of that numeral. As used herein, the term “substantially free” is intended to mean an amount less than about 5.0 wt. %, less than 3.0 wt. %, less than 1.0 wt. %; preferably less than about 0.5 wt. %, and more preferably less than about 0.25 wt. % of the composition.

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, patent applications, publications, and other references cited or referred to herein are incorporated by reference in their entireties for all purposes. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

[0036] In the description of examples disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present disclosure. Relative terms such as "lower," "upper," “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g.,“horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing (if applicable) under discussion. These relative terms are for convenience of description only and, unless specified otherwise, do not require that the apparatus be constructed or operated in a particular orientation.

[0037] As used herein, terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and the like refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Accordingly, the disclosure is not limited to such examples illustrating certain combinations of features that may exist alone or in combination with other features.

[0038] The present disclosure relates to acoustic felt structures. In one aspect, the disclosed acoustic felt structures are comprised of natural, sustainable, biodegradable materials. The present disclosure balances material and mechanical property considerations including acoustics, aesthetics, fire safety, structural integrity, and environmental impact.

[0039] Referring to Fig. 1, disclosed is an acoustic structure 100 and building structure assembly 50. The acoustic structure 100 may be suitable as a ceiling structure or a wall structure, such as a panel, blade, lattice, or other aesthetic design, designed to provide acoustic properties as described herein while offering desired aesthetics. The acoustic structure 100 may be part of a building structure assembly 50 such that it is coupled with building attachment hardware 70 configured to removably couple the acoustic structure 100 to a building structure. In one example, the building attachment hardware 70 is integrally formed with the acoustic structure 100. In another example, the building attachment hardware 70 is removably attachable to the acoustic structure 100.

[0040] Referring to Fig. 2, the acoustic structure 100 is characterized by a width Wp ranging from about 6 inches to about 10 inches. The acoustic structure 100 is further characterized by a length Lp ranging from about 48 inches to about 96 inches. Referring to Fig. 3, the acoustic structure 100 is further characterized by its thickness tp ranging from about 0.35 inches to about 2 inches.

[0041] The acoustic structure 100 includes a substrate 110 having a first major surface 112 opposite a second major surface 114 and a side surface 113 extending therebetween. The side surface includes a first side 113a, a second side 113b, a third side 113c, and a fourth side 113d. the building attachment hardware 70 may be coupled to the second side surface 113b of acoustic structure 100. In other examples, the building attachment hardware 70 may be coupled to eitherthe first and / or second major surfaces 112, 114 of the acoustic structure 100 at a location immediately adjacent to the second side surface 113b of the acoustic structure 100.

[0042] In one or more examples, the substrate 110 includes natural fibrous material in the form of a web 120. The substrate is comprised of about 85% to about 99% natural materials- including all values and sub-ranges there-between. In one example, the web 120 is nonwoven. The web 120 may be formed by being carded, cross-lapped, and needle punched. In another example, the web 120 may be carded, air-laid, and needle punched.

[0043] In one example, the web 120 includes 100% of a natural fibrous material. The natural fibrous material may include one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, or wool. In another example, the natural fibrous material includes hemp. In yet another example, the web 120 includes a blend of natural fibrous material and synthetic fibrous material. The synthetic fibrous material may include one or more of polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, or nylon.

[0044] The web 120 may be characterized by its material and physical properties. In one example, the web 120 has basis weight ranging from about 300 gsm to about 2500 gsm, from about 500 gsm to about 2000 gsm, from about 750 gsm to about 1850 gsm, from about 1000 gsm to about 1700 gsm, or from about 1200 gsm to about 1600 gsm - including all values and sub-ranges therebetween. In another aspect, the web 12 has a porosity ranging from about 70% to about 95%, from about 75% to about 95%, from about 80% to about 95%, from about 85% to about 95%, or greater than about 85%- including all values and sub-ranges there-between.

[0045] The web 120 may have any thickness needed for the desired application. In one example, the web 120 has a thickness ranging from about 5mm to about 50mm, from about 8mm to about 40mm, from about 10mm to about 15mm, or from about 9mm to about 12mm - including all values and sub-ranges there-between.

[0046] In one or more examples, the substrate 110 includes a binding composition infused in the web such that it is present throughout the web 120 among the fibers. The binding composition is selected to cure the web 120 and bind or fuse the fibers together to provide requisite rigidity and strength of the acoustic structure 100.

[0047] The binding composition includes one of a waterborne reactive emulsion or a thermoplastic latex. In one example, the binding composition includes a cross-linking alkyd, a polyester, an acrylic or an epoxy resin. In another example, the binding composition includes a biobased cross-linking alkyd resin. In yet another example, the binding composition includes styrene acrylic, vinyl acrylic, or polyvinyl acetate. The binding composition may be further defined by its glass transition temperature. In one example, the binding composition has a glass transition temperature above 50°C.

[0048] In one or more examples, the binding composition includes at least one filler. The at least one filler is selected from a flame retardant, biocide or antimicrobial, dispersant, pigment, viscosity modifier, iron drier, and foaming agent.

[0049] In one or more examples, the binding composition includes a flame retardant. In one example, the flame retardant is present in an amount from about 2 wt. % to about 15 wt. %, from about 3 wt. % to about 9 wt. %, or from about 4 wt. % to about 8 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition. In one example, the flame retardant includes aluminum trihydrate. In another example, the flame retardant includes ammonium polyphosphate.

[0050] In one or more examples, the binding composition includes a pigment. The pigment may include one or more of calcium carbonate, titanium dioxide, barium sulfate, diatomaceous earth, and aluminum hydroxide. In one example, the pigment is present in an amount from about 10 wt. % to about 70 wt. %, from about 15 wt. % to about 65 wt. %, from about 20 wt. % to about 60 wt.%, or from about 30 wt. % to about 55 wt.% - including all values and sub-ranges therebetween, based on the total dry weight of the composition. In one example, the binding composition includes calcium carbonate present in an amount from about 20 wt. % to about 40 wt. %, from about 25 wt. % to about 35 wt. %, or from about 38 wt. % to about 32 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0051] In one or more examples, the binding composition includes a surfactant dispersant. In one example, the surfactant dispersant is present in an amount from about 0.05 wt. % to about 1.0 wt. %, from about 0.07 to about 0.5 wt. %, or from about 0.1 wt. % to about 0. 5 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0052] In one or more examples, the binding composition includes an iron catalyst. In one example, the iron catalyst is present in an amount from about 0.001 wt. % to about 0.01 wt. %, from about 0.002 wt. % to about 0.008 wt. %, or from about 0.003 wt. % to about 0.006 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0053] In one or more examples, the binding composition includes a foaming agent. In one example, the foaming agent is present in an amount from about 0.05 wt. % to about 3 wt. %, from about 0.08 wt. % to about 2 wt. %, or from about 0.1 wt. % to about 1.0 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition. In one example, the foaming agent is a biobased foaming agent derived from sugar.

[0054] In one or more examples, the binding composition includes a viscosity modifier. In one example, the viscosity modifier is present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition. In another example, the viscosity modifier is present in an amount from about 0.3 wt. % to 2 wt. %, based on the total wet weight of the composition.

[0055] The acoustic structure 100 may be further characterized by its acoustic properties. In one example, the acoustic structure 100 is defined by having a sufficiently high noise reduction coefficient (NRC) rating to be characterized as an acoustic structure 100. NRC is a measure of sound energy absorption of a material. An NRC rating of 0 is a perfect sound reflection material. An NRC rating of 1 is a perfect sound absorption material. In one example, the acoustic structure 100 has an NRC value ranging from about 0.65 to about 0.90.

[0056] Referring to Fig. 4 and Fig. 5, the acoustic structure 100 may part of an acoustic system 10 including more than one acoustic structure 100. In the acoustic system 10, each acoustic structure 100 may be coupled to a support structure 7, such as a strut 5. The support structure 7 may include one or more parallel stmts 5. The support structure 7 may be installed into an interior space 2 by attaching strut attachment hardware 6 directly or indirectly to both the stmts 5 and a stmctural barrier 4. In the installed state, the acoustic system 10 may comprise the acoustic structure 100 being supported by the stmts 5 of the support stmcture 7 in the interior space 2 by the panel attachment hardware 70.

[0057] In the installed state, each acoustic structure 100 of the plurality of acoustic stmcture may be horizontally offset by a lateral offset distance Di that is a positive non-zero value. Specifically, the later offset distance Di may be the distance between the first major surface 112 of a first acoustic structure 100 and the second major surface 114 of an adjacent-most second acoustic structure 100. The lateral offset distance Di may range from about 10 cm to about 244 cm - including all distances and sub-ranges there-between.

[0058] Also disclosed is a method for manufacturing an acoustic structure 100. In one example, the method includes providing a web 120 having a first surface 122 opposite a second surface 124. The web 120 is comprised of non-woven natural fibrous material, such as hemp, jute, kenaf, flax, sisal, fique, coir, cotton, or wool.

[0059] In one example, the web 120 is nonwoven. The web 120 may be formed by being carded, cross-lapped, and needle punched. In another example, the web 120 may be carded, air-laid, and needle punched.

[0060] In one example, the web 120 includes 100% of a natural fibrous material. In another example, the natural fibrous material includes hemp. In yet another example, the web 120 includes a blend of natural fibrous material and synthetic fibrous material. The synthetic fibrous material may include one or more of polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, or nylon.

[0061] The web 120 may be characterized by its material and physical properties. In one example, the web 120 has basis weight ranging from about 300 gsm to about 2500 gsm, from about 500 gsm to about 2000 gsm, from about 750 gsm to about 1850 gsm, from about 1000 gsm to about 1700 gsm, or from about 1200 gsm to about 1600 gsm - including all values and sub-ranges therebetween. In another aspect, the web 12 has a porosity ranging from about 70% to about 95%, from about 75% to about 95%, from about 80% to about 95%, from about 85% to about 95%, or greater than about 85%- including all values and sub-ranges there-between.

[0062] The web 120 may have any thickness needed for the desired application. In one example, the web 120 has a thickness ranging from about 5mm to about 50mm, from about 8mm to about 40mm, from about 10mm to about 15mm, or from about 9mm to about 12mm- including all values and sub-ranges there-between.

[0063] The method includes applying a binding composition to at least one of the first surface 122 and the second surface 124 of the web 120. The applying may be achieved by spraying the binding composition onto at least one of the first surface 122 and the second surface 124 of the web 120 such that the binding composition infuses the web. In another example, the applying includes foaming the binding composition and distributing the foamed binding composition over at least one of the first surface 122 and the second surface 124 of the web 120 such that the foamed binding composition penetrates the web 120 and is distributed around the nonwoven fibers of the web 120.

[0064] In yet another example, the applying includes dipping the web 120 into a trough or other container having the binding composition to saturate the web 120 with the bonding composition, and subsequently squeezing the web 120 in the nip between two rollers to remove excess binding composition from the web 120. The latter method of applying may be referred to as a dip and squeeze method.

[0065] The binding composition includes one of a waterborne reactive emulsion or a thermoplastic latex. In one example, the binding composition includes a cross-linking alkyd, a polyester, an acrylic or an epoxy resin. In another example, the binding composition includes a biobased crosslinking alkyd resin. In yet another example, the binding composition includes styrene acrylic, vinyl acrylic, or polyvinyl acetate. The binding composition may be further defined by its glass transition temperature. In one example, the binding composition has a glass transition temperature above 50°C.

[0066] The binding composition may include a flame retardant. In one example, the flame retardant is present in an amount from about 2 wt. % to about 15 wt. %, from about 3 wt. % to about 9 wt. %, or from about 4 wt. % to about 8 wt. %- including all values and sub-ranges therebetween, based on the total dry weight of the composition. In one example, the flame retardant includes aluminum trihydrate. In another example, the flame retardant includes ammonium polyphosphate.

[0067] The binding composition may include a pigment. The pigment may include one or more of calcium carbonate, titanium dioxide, barium sulfate, diatomaceous earth, and aluminum hydroxide. In one example, the pigment is present in an amount from about 10 wt. % to about 70 wt. %, from about 15 wt. % to about 65 wt. %, from about 20 wt. % to about 60 wt.%, or from about 30 wt. % to about 55 wt.% - including all values and sub-ranges there-between, based on the total dry weight of the composition. In one example, the binding composition includes calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, from about 25 wt. % to about 45 wt. %, or from about 30 wt. % to about 40 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0068] In one or more examples, the binding composition includes a surfactant dispersant. In one example, the surfactant dispersant is present in an amount from about 0.05 wt. % to about 1.0 wt. %, from about 0.07 to about 0.5 wt. %, or from about 0.1 wt. % to about 0. 5 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0069] In one or more examples, the binding composition includes an iron catalyst. In one example, the iron catalyst is present in an amount from about 0.001 wt. % to about 0.01 wt. %, from about 0.002 wt. % to about 0.008 wt. %, or from about 0.003 wt. % to about 0.006 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition.

[0070] In one or more examples, the binding composition includes a foaming agent. In one example, the foaming agent is present in an amount from about 0.5 wt. % to about 3 wt. %, from about 0.7 wt. % to about 2 wt. %, or from about 1 wt. % to about 1.5 wt. %- including all values and sub-ranges there-between, based on the total dry weight of the composition. In one example, the foaming agent is a biobased foaming agent derived from sugar.

[0071] In one or more examples, the binding composition includes a viscosity modifier. In one example, the viscosity modifier is present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0072] In one or more examples, the method includes applying the binding composition to the opposing surface of the web 120. The applying may be achieved by spraying the binding composition onto the opposing surface of the web 120 such that the binding composition infuses the web. In another example, the applying includes foaming the binding composition and distributing the foamed binding composition over the opposing surface of the web 120 such that the foamed binding composition penetrates the entire thickness of the web 120 and is distributed around the nonwoven fibers of the web 120.

[0073] In yet another example, the applying includes dipping the web 120 into a trough or other container having the binding composition to saturate the web 120 with the bonding composition, and subsequently squeezing the web 120 in the nip between two rollers to remove excess binding composition from the web 120. The latter method of applying may be referred to as a dip and squeeze method.

[0074] In one or more examples, the method includes infusing the binding composition into the web 120. The infusing may be achieved simultaneously with the applying or concurrent to the applying such that after the binding composition is applied to the web 120, the binding composition infuses the web 120.

[0075] In one or more examples, the method includes drying the web 120 after applying the binding composition. In one example, the drying is performed at room temperature. In anotherexample, the drying is performed at a temperature from about 120 F to about 160 F. In another example, the drying is performed for a period of time from about 5 minutes to about 240 minutes.

[0076] In one or more examples, the method includes curing the web 120 after applying the binding composition. The curing may occur simultaneously with the drying such that upon drying, the binding composition binds the natural fibrous material of the web 120.

[0077] In one or more examples, the method for manufacturing an acoustic structure 100 includes providing a web 120 of non-woven natural fibrous material having a first surface 122 opposite a second surface 124, mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion, foaming the binder dispersion to form a foamed binder dispersion, and applying the foamed binder dispersion to at least one of the first surface 122 and the second surface 124 of the web 120.

[0078] In one or more examples, the method for manufacturing an acoustic structure 100 includes carding a plurality of natural fibers, blending the plurality of natural fibers, forming the plurality of natural fibers into a mat, lapping the mat to form a web 120 having a first surface 122 opposed a second surface 124, needle punching the web 120, mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion, foaming the binder dispersion to form a foamed binder dispersion, applying the foamed binder dispersion to at least one of the first surface 122 and the second surface 124 of the web 120, drying the web 120, and curing the web to yield the acoustic structure 100.

[0079] The disclosure may be further characterized by the following clauses:

[0080] Clause 1: An acoustic structure comprising: a substrate having a first surface opposite a second surface, the substrate comprising: a web comprising a non-woven natural fibrous material; and a binding composition distributed throughout the web, wherein the binding composition comprises a waterborne reactive emulsion or a thermoplastic latex.

[0081] Clause 2: The acoustic structure of clause 1, wherein the non-woven natural fibrous material is felt comprising one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool.

[0082] Clause 3: The acoustic structure of any one of clauses 1 or 2, wherein the non-woven natural fibrous material comprises hemp.

[0083] Clause 4: The acoustic structure of any one of clauses 1 to 3, wherein the web has basis weight ranging from about 300 gsm to about 2500 gsm.

[0084] Clause 5: The acoustic structure of any one of clauses 1 to 4, wherein the web has a thickness ranging from about 5mm to about 50 mm.

[0085] Clause 6: The acoustic structure of any one of clauses 1 to 5, wherein the web has a porosity ranging from about 70% to about 95%.

[0086] Clause 7: The acoustic structure of any one of clauses 1 to 6, wherein the web further comprises at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0087] Clause 8: The acoustic structure of any one of clauses 1 to 7, wherein the binding composition comprises a cross-linking alkyd, a polyester, an acrylic or an epoxy resin.

[0088] Clause 9: The acoustic structure of any one of clauses 1 to 8 wherein the binding composition comprises a biobased cross-linking alkyd resin.

[0089] Clause 10: The acoustic structure of any one of clauses 1 to 9, wherein the binding composition comprises styrene acrylic, vinyl acrylic, or polyvinyl acetate.

[0090] Clause 11: The acoustic structure of any one of clauses 1 to 10, wherein the binding composition has a glass transition temperature above 50°C

[0091] Clause 12: The acoustic structure of any one of clauses 1 to 11, wherein the binding composition further comprises a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition.

[0092] Clause 13: The acoustic structure of any one of clauses 1 to 12, wherein the flame retardant comprises one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides.

[0093] Clause 14: The acoustic structure of any one of clauses 1 to 13, wherein the flame retardant comprises ammonium polyphosphate.

[0094] Clause 15: The acoustic structure of any one of clauses 1 to 14, wherein the flame retardant comprises aluminum trihydrate.

[0095] Clause 16: The acoustic structure of any one of clauses 1 to 15, wherein the binding composition further comprises one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition.

[0096] Clause 17: The acoustic structure of any one of clauses 1 to 16, wherein the binding composition further comprises calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition.

[0097] Clause 18: The acoustic structure of any one of clauses 1 to 17, wherein the binding composition further comprises a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition.

[0098] Clause 19: The acoustic structure of any one of clauses 1 to 18, wherein the binding composition further comprises an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition.

[0099] Clause 20: The acoustic structure of any one of clauses 1 to 19, wherein the binding composition further comprises a foaming agent present in an amount from about 0.5 wt. % to about 3 wt. %, based on the total dry weight of the composition.

[0100] Clause 21: The acoustic structure of any one of clauses 1 to 20, wherein the foaming agent is a biobased foaming agent derived from sugar.

[0101] Clause 22: The acoustic structure of any one of clauses 1 to 21, wherein the binding composition further comprises a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0102] Clause 23: The acoustic structure of any one of clauses 1 to 22, wherein the binding composition further comprises a biocide.

[0103] Clause 24: The acoustic structure of any one of clauses 1 to 23, wherein the substrate is comprised of about 85% to about 99% natural materials.

[0104] Clause 25: The acoustic structure of any one of clauses 1 to 24 exhibiting an NRC from about 0.65 to about 0.90.

[0105] Clause 26: A ceiling structure formed from the acoustic structure of any one of clauses 1 to 25.

[0106] Clause 27 : A wall structure formed from the acoustic structure of any one of clauses 1 to 25.

[0107] Clause 28: A method for manufacturing an acoustic structure, the method comprising: providing a web having a first surface opposite a second surface, the web comprised of non-woven natural fibrous material; and applying a binding composition to at least one of the first surface and the second surface, wherein the binding composition comprises a waterborne reactive emulsion or a thermoplastic latex.

[0108] Clause 29: The method according to clause 28, further comprising applying the binding composition to the opposing surface of the web.

[0109] Clause 30: The method according to any one of clauses 28 or 29, wherein the applying comprises dipping the web into the binding composition.

[0110] Clause 31 : The method according to any one of clauses 28 to 30, further comprising drying the web after applying the binding composition.

[0111] Clause 32: The method according to any one of clauses 28 to 31, further comprising curing the web after applying the binding composition.

[0112] Clause 33: The method according to any one of clauses 28 to 32, wherein the non-woven natural fibrous material comprises one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool.

[0113] Clause 34: The method according to any one of clauses 28 to 33, wherein the non-woven natural fibrous material comprises hemp.

[0114] Clause 35: The method according to any one of clauses 28 to 34, wherein the web has basis weight ranging from about 300 gsm to about 2500 gsm.

[0115] Clause 36: The method according to any one of clauses 28 to 35, wherein the web has a thickness ranging from about 5mm to about 50 mm.

[0116] Clause 37: The method according to any one of clauses 28 to 36, wherein the web has a porosity ranging from about 70% to about 95%.

[0117] Clause 38: The method according to any one of clauses 28 to 37, wherein the web further comprises at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0118] Clause 39: The method according to any one of clauses 28 to 38, wherein the binding composition comprises a cross-linking alkyd, a polyester, an acrylic or an epoxy resin.

[0119] Clause 40: The method according to any one of clauses 28 to 39, wherein the binding composition comprises a biobased cross-linking alkyd resin.

[0120] Clause 41: The method according to any one of clauses 28 to 40, wherein the binding composition comprises styrene acrylic, vinyl acrylic, or polyvinyl acetate.

[0121] Clause 42: The method according to any one of clauses 28 to 41, wherein the binding composition has a glass transition temperature above 50°C

[0122] Clause 43: The method according to any one of clauses 28 to 42, wherein the binding composition further comprises a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition.

[0123] Clause 44: The method according to any one of clauses 28 to 43, wherein the flame retardant comprises one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides.

[0124] Clause 45: The method according to clause 44, wherein the flame retardant comprises ammonium polyphosphate.

[0125] Clause 46: The method according to any one of clauses 44 or 45, wherein the flame retardant comprises aluminum trihydrate.

[0126] Clause 47: The method according to any one of clauses 28 to 46, wherein the binding composition further comprises one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition.

[0127] Clause 48: The method according to any one of clauses 28 to 47, wherein the binding composition further comprises calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition.

[0128] Clause 49: The method according to any one of clauses 28 to 48, wherein the binding composition further comprises a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition.

[0129] Clause 50: The method according to any one of clauses 28 to 49, wherein the binding composition further comprises an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition.

[0130] Clause 51: The method according to any one of clauses 28 to 50, wherein the binding composition further comprises a foaming agent present in an amount from about 0.5 wt. % to about 3 wt. %, based on the total dry weight of the composition.

[0131] Clause 52: The method according to any one of clauses 28 to 51, wherein the foaming agent is a biobased foaming agent derived from sugar.

[0132] Clause 53: The method according to any one of clauses 28 to 52, wherein the binding composition further comprises a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0133] Clause 54: The method according to any one of clauses 28 to 53, wherein the binding composition further comprises a biocide.

[0134] Clause 55: The method according to any one of clauses 28 to 54, wherein the substrate is comprised of about 85% to about 99% natural materials.

[0135] Clause 56: The method according to any one of clauses 28 to 55, wherein the acoustic structure exhibits an NRC from about 0.65 to about 0.90.

[0136] Clause 57: A method for manufacturing an acoustic structure, the method comprising: providing a web of non-woven natural fibrous material having a first surface opposite a second surface; mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion; foaming the binder dispersion to form a foamed binder dispersion; and applying the foamed binder dispersion to at least one of the first surface and the second surface of the web.

[0137] Clause 58: The method according to clause 57, further comprising applying the foamed binder dispersion to the opposing surface of the web.

[0138] Clause 59: The method according to any one of clauses 57 or 58, further comprising drying the web after applying the foamed binder dispersion.

[0139] Clause 60: The method according to any one of clauses 57 to 59, wherein the drying is performed at a temperature below 100 °C.

[0140] Clause 61: The method according to any one of clauses 57 to 60, wherein the non-woven natural fibrous material comprises one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool.

[0141] Clause 62: The method according to any one of clauses 57 to 61, wherein the non-woven natural fibrous material comprises hemp.

[0142] Clause 63: The method according to any one of clauses 57 to 62, wherein the web has basis weight ranging from about 300 gsm to about 2500 gsm.

[0143] Clause 64: The method according to any one of clauses 57 to 63, wherein the web has a thickness ranging from about 5mm to about 50 mm.

[0144] Clause 65: The method according to any one of clauses 57 to 64, wherein the web has a porosity ranging from about 70% to about 95%.

[0145] Clause 66: The method according to any one of clauses 57 to 65, wherein the web further comprises at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

[0146] Clause 67: The method according to any one of clauses 57 to 66, wherein the binding composition comprises a cross-linking alkyd, a polyester, an acrylic or an epoxy resin.

[0147] Clause 68: The method according to any one of clauses 57 to 67, wherein the binding composition comprises a biobased cross-linking alkyd resin.

[0148] Clause 69: The method according to any one of clauses 57 to 68, wherein the binding composition comprises styrene acrylic, vinyl acrylic, or polyvinyl acetate.

[0149] Clause 70: The method according to any one of clauses 57 to 69, wherein the binding composition has a glass transition temperature above 50°C

[0150] Clause 71: The method according to any one of clauses 57 to 70, wherein the binding composition further comprises a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition.

[0151] Clause 72: The method according to clause 71, wherein the flame retardant comprises one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides.

[0152] Clause 73: The method according to any one of clauses 71 or 72, wherein the flame retardant comprises ammonium polyphosphate.

[0153] Clause 74: The method according to any one of clauses 71 to 73, wherein the flame retardant comprises aluminum trihydrate.

[0154] Clause 75: The method according to any one of clauses 57 to 74, wherein the binding composition further comprises one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition.

[0155] Clause 76: The method according to any one of clauses 57 to 75, wherein the binding composition further comprises calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition.

[0156] Clause 77: The method according to any one of clauses 57 to 76, wherein the binding composition further comprises a surfactant dispersant present in an amount from about 0.05 wt. % to about 1.0 wt. %, based on the total dry weight of the composition.

[0157] Clause 78: The method according to any one of clauses 57 to 77, wherein the binding composition further comprises an iron catalyst present in an amount from about 0.001 wt. % to about 0.01 wt. %, based on the total dry weight of the composition.

[0158] Clause 79: The method according to any one of clauses 57 to 78, wherein the binding composition further comprises a foaming agent present in an amount from about 0.5 wt. % to about 3 wt. %, based on the total dry weight of the composition.

[0159] Clause 80: The method according to clause 79, wherein the foaming agent is a biobased foaming agent derived from sugar.

[0160] Clause 81: The method according to any one of clauses 57 to 80, wherein the binding composition further comprises a viscosity modifier present in an amount from about 0.17 wt. % to about 1.13 wt. %, based on the total dry weight of the composition.

[0161] Clause 82: The method according to any one of clauses 57 to 81, wherein the web is comprised of about 85% to about 99% natural materials.

[0162] Clause 83: The method according to any one of clauses 57 to 82, wherein the acoustic structure exhibits an NRC from about 0.65 to about 0.90.

[0163] Clause 84: A method for manufacturing an acoustic structure, the method comprising: carding a plurality of natural fibers; blending the plurality of natural fibers; forming the plurality of natural fibers into a mat; lapping the mat to form a web having a first surface opposed a second surface; needle punching the web; mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion; foaming the binder dispersion to form a foamed binder dispersion; applying the foamed binder dispersion to at least one of the first surface and the second surface of the web; drying the web; and curing the web to yield an acoustic structure.EXAMPLES

[0164] The examples and other implementations described herein are exemplary and not intended to be limiting in describing the full scope of compositions and methods of this disclosure. Equivalent changes, modifications and variations of specific implementations, materials, compositions, and methods may be made within the scope of the present disclosure, with substantially similar results.

[0165] Table 1 below illustrates the composition of Example 1 of an acoustic structure 100 as described herein.TABLE 1

[0166] Table 2 illustrates the composition of Example 2 of an acoustic structure 100 as described herein.TABLE 2

[0167] Table 3 illustrates the composition of Example 3 of a binding composition applied to and infused into a web as disclosed herein.TABLE 3

[0168] While the present disclosure has been described with reference to several examples, which examples have been set forth in considerable detail for the purposes of making a complete disclosure of the disclosure, such examples are merely representative and are not intended to be limiting or represent an exhaustive enumeration of all aspects of the disclosure. The scope of the disclosure is to be determined from the claims appended hereto. Further, it will be apparent to those of skill in the art that numerous changes may be made in such details without departing from the spirit and the principles of the disclosure.

Claims

CLAIMSWhat Is Claimed Is:

1. An acoustic structure comprising: a substrate having a first surface opposite a second surface, the substrate comprising: a web comprising a non-woven natural fibrous material; and a binding composition distributed throughout the web, wherein the binding composition comprises a waterborne reactive emulsion or a thermoplastic latex.

2. The acoustic structure of claim 1, wherein the non-woven natural fibrous material is felt comprising one or more of hemp, jute, kenaf, flax, sisal, fique, coir, cotton, and wool.

3. The acoustic structure of any one of claims 1 to 2, wherein the web has basis weight ranging from about 300 gsm to about 2500 gsm.

4. The acoustic structure of any one of claims 1 to 3, wherein the web has a porosity ranging from about 70% to about 95%.

5. The acoustic structure of any one of claims 1 to 4, wherein the web further comprises at least one synthetic fibrous material selected from Polyester PET, polypropylene, polyethylene, acrylic, poly(lactic acid) PLA, and nylon.

6. The acoustic structure of any one of claims 1 to 5, wherein the binding composition comprises a cross-linking alkyd, a polyester, an acrylic or an epoxy resin.

7. The acoustic structure of any one of claims 1 to 6, wherein the binding composition comprises a biobased cross-linking alkyd resin.

8. The acoustic structure of any one of claims 1 to 7, wherein the binding composition comprises styrene acrylic, vinyl acrylic, or polyvinyl acetate.

9. The acoustic structure of any one of claims 1 to 8, wherein the binding composition further comprises a flame retardant present in an amount from about 2 wt. % to about 15 wt. %, based on the total dry weight of the composition.

10. The acoustic structure of any one of claims 1 to 9, wherein the flame retardant comprises one or more phosphates, sulfates, certain borates and hydrated minerals, halogens compounds and antimony oxides.

11. The acoustic structure of any one of claims 1 to 10, wherein the binding composition further comprises one or more pigment present in an amount from about 10 wt. % to about 70 wt. %, based on the total dry weight of the composition.

12. The acoustic structure of any one of claims 1 to 11 , wherein the binding composition further comprises calcium carbonate present in an amount from about 20 wt. % to about 50 wt. %, based on the total dry weight of the composition.

13. The acoustic structure of any one of claims 1 to 12, wherein the binding composition further comprises a foaming agent present in an amount from about 0.5 wt. % to about 3 wt. %, based on the total dry weight of the composition.

14. A ceiling structure formed from the acoustic structure of any one of claims 1 to 13.

15. A wall structure formed from the acoustic structure of any one of claims 1 to 14.

16. A method for manufacturing an acoustic structure, the method comprising: providing a web having a first surface opposite a second surface, the web comprised of non-woven natural fibrous material; and applying a binding composition to at least one of the first surface and the second surface, wherein the binding composition comprises a waterborne reactive emulsion or a thermoplastic latex.

17. The method according to claim 16, wherein the applying comprises dipping the web into the binding composition.

18. The method according to any one of claims 16 to 17, further comprising drying the web after applying the binding composition.

19. The method according to any one of claims 16 to 18, further comprising curing the web after applying the binding composition.

20. A method for manufacturing an acoustic structure, the method comprising: providing a web of non-woven natural fibrous material having a first surface opposite a second surface; mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion;foaming the binder dispersion to form a foamed binder dispersion; and applying the foamed binder dispersion to at least one of the first surface and the second surface of the web.

21. The method according to claim 20, further comprising drying the web after applying the foamed binder dispersion.

22. The method according to any one of claims 20 to 21, wherein the drying is performed at a temperature below 100 °C.

23. A method for manufacturing an acoustic structure, the method comprising: carding a plurality of natural fibers; blending the plurality of natural fibers; forming the plurality of natural fibers into a mat; lapping the mat to form a web having a first surface opposed a second surface; needle punching the web; mixing a liquid carrier with a waterborne reactive emulsion or a thermoplastic latex to form a binder dispersion; foaming the binder dispersion to form a foamed binder dispersion; applying the foamed binder dispersion to at least one of the first surface and the second surface of the web; drying the web; and curing the web to yield an acoustic structure.

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