Method for manufacturing sound-absorbing member

Abstract

A method for manufacturing a sound-absorbing member that is obtained by laminating a plurality of sheet materials, the method comprising a compression step in which a plurality of sheet materials stacked together with an adhesive therebetween are compressed in the thickness direction of the sheet materials to obtain a compressed body, wherein at least one of the plurality of sheet materials is a porous body, and the thickness of at least one of the sheet materials that is a porous body in the compressed body is 70-99% of the pre-compression thickness.

Description

Manufacturing method of sound-absorbing material

[0001] The present disclosure relates to a method for manufacturing a sound-absorbing material, and more particularly to a method for manufacturing a sound-absorbing material formed by stacking a plurality of sheet-like materials.

[0002] In vehicles, buildings, electrical appliances, etc., porous materials such as nonwoven fabrics and resin foams are used as sound-absorbing materials to reduce noise from noise sources (see, for example, Patent Documents 1 and 2).

[0003] JP 2012-214957 A JP 2019-183008 A

[0004] In order to deal with various noise sources, sound-absorbing materials are required to have sound-absorbing performance that matches the frequency of the noise source. However, in the case of a single porous sound-absorbing material, increasing the sound-absorbing performance at low frequencies (for example, 1500 Hz or less) requires a significant increase in thickness and weight. Considering practical requirements such as space saving and weight reduction, it is desirable to improve the sound-absorbing performance at low frequencies while reducing the thickness of the sound-absorbing material.

[0005] The present inventors have noticed that a laminated structure of porous materials or a porous material and a thin film is effective in improving sound absorption performance in the low frequency range and reducing the thickness of the material. They have investigated the production of a sound-absorbing material by laminating multiple sheet-like materials, and have found the following problems: Compression is necessary to firmly bond the sheet-like materials together, but if the thickness of the laminate is reduced too much by compression, the sound absorption performance becomes insufficient. On the other hand, if the compression is light to prevent the thickness reduction, the bonding between the sheet-like materials becomes insufficient, resulting in a failure to achieve practical durability or the improvement in sound absorption performance in the low frequency range that is achieved by the laminated structure.

[0006] An object of the present disclosure is to provide a method for manufacturing a sound-absorbing material that can achieve both excellent sound-absorbing performance in the low frequency range and durability.

[0007] The present disclosure relates to the following inventions [1] to

[13] .

[0008] [1] A method for producing a sound-absorbing material comprising a plurality of laminated sheet-like materials, the method comprising a compression step of compressing the plurality of laminated sheet-like materials, laminated with an adhesive, in the thickness direction to obtain a compressed body, wherein at least one of the plurality of laminated sheet-like materials is porous, and the thickness of at least one of the porous sheet-like materials in the compressed body is 70 to 99% of its thickness before compression. [2] A method for producing the sound-absorbing material according to [1] above, wherein the compression step results in a compression ratio of 10 to 90% in the thickness direction of the laminated sheet-like materials. [3] A method for producing the sound-absorbing material according to [1] or [2] above, wherein the compression step involves compressing the laminated sheet-like materials at a temperature of 10 to 200°C. [4] A method for producing the sound-absorbing material according to any of [1] to [3] above, wherein the adhesive is applied by spray coating or transfer using a roll coater. [5] A method for producing the sound-absorbing material according to any of [1] to [4] above, wherein the method is a roll-to-roll process. [6] A method for producing a sound-absorbing material according to any one of [1] to [4] above, using a roll-to-sheet method. [7] A method for producing a sound-absorbing material according to any one of [1] to [6] above, in which the porous sheet-like material is a nonwoven fabric or a resin foam. [8] A method for producing a sound-absorbing material according to any one of [1] to [7] above, in which at least one of the plurality of sheet-like materials is a resin film containing at least one selected from the group consisting of polyolefin resin, polyester resin, and polyurethane resin. [9] A method for producing a sound-absorbing material according to [8] above, in which the plurality of overlapping sheet-like materials includes a structure in which a porous sheet-like material and a resin sheet are overlapped via an adhesive.

[10] A method for producing a sound-absorbing material according to any one of [1] to [9] above, in which two or more of the plurality of sheet-like materials are porous, and the plurality of overlapping sheet-like materials includes a structure in which a porous sheet-like material and a porous sheet-like material are overlapped via an adhesive.

[11] A method for producing a sound-absorbing material according to any one of [1] to

[10] above, wherein two or more of the plurality of sheet-like materials are porous, at least one of the plurality of sheet-like materials is a resin film containing at least one resin selected from the group consisting of polyolefin resin, polyester resin, and polyurethane resin, and the stacked plurality of sheet-like materials includes a structure in which the resin film, the porous sheet-like material, and the porous sheet-like material are stacked in this order via an adhesive.

[12] A method for producing a sound-absorbing material according to any one of [1] to

[11] above, wherein the adhesive contains at least one adhesive component selected from the group consisting of polyolefin-based resin, polyester-based resin, polyurethane-based resin, acrylic resin, and silicone-based resin.

[13] A method for producing a sound-absorbing material according to any one of [1] to

[12] above, wherein the adhesive is a hot-melt adhesive.

[0009] According to the present disclosure, it is possible to provide a method for manufacturing a sound-absorbing material that can achieve both excellent sound-absorbing performance in the low frequency range and durability.

[0010] For example, according to the method for producing a sound-absorbing material described in [1] above, a compressed body can be obtained in the compression step, in which a porous structure that enables sound energy attenuation is incorporated with a thickness and adhesive strength that ensures sufficient sound-absorbing performance. A sound-absorbing material containing such a compressed body can have excellent sound-absorbing performance in the low-frequency range while having sufficient durability for practical use.

[0011] FIG. 1 is a schematic diagram for explaining a compression step in a manufacturing method of a sound-absorbing material. FIG. 2 is a schematic diagram for explaining a compression step in a manufacturing method of a sound-absorbing material. FIG. 3 is a schematic diagram for explaining an example of a configuration of a sound-absorbing material. FIG. 4 is a schematic diagram for explaining an example of a manufacturing method of a sound-absorbing material. FIG. 5 is a schematic diagram for explaining an example of a manufacturing method of a sound-absorbing material.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings where necessary. However, the present disclosure is not limited to the following embodiments.

[0013] <Method for manufacturing sound-absorbing material> The method for manufacturing sound-absorbing material of this embodiment is a method for manufacturing a sound-absorbing material formed by stacking a plurality of sheet-like materials, and includes a compression step in which the plurality of sheet-like materials stacked together with an adhesive are compressed in the thickness direction to obtain a compressed body, and at least one of the plurality of sheet-like materials is a porous body.

[0014] Examples of the porous sheet-like material include resin foam, nonwoven fabric, porous polymer material, porous ceramic, etc. Among these, the porous sheet-like material may be resin foam or nonwoven fabric from the viewpoint of excellent sound absorption characteristics in the low frequency range.

[0015] Fibers constituting the nonwoven fabric include organic fibers and inorganic fibers. Examples of organic fibers include polyolefin fibers such as polyethylene (low density or high density), polypropylene, copolymerized polyethylene, and copolymerized polypropylene; polyester fibers such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; acrylic fibers, polyamide fibers, nylon fibers, rayon fibers, and natural fibers such as wool. Examples of inorganic fibers include glass fibers, metal fibers, ceramic fibers, and carbon fibers. The fibers constituting the nonwoven fabric may contain one or more of these fibers.

[0016] The average fiber diameter of the fibers constituting the nonwoven fabric may be 1 to 40 μm, 2 to 30 μm, or 3 to 25 μm, from the viewpoint of sound absorption performance and shape retention.

[0017] From the viewpoint of achieving excellent sound absorption characteristics in the low frequency range, the thickness of the porous sheet-like material can be 0.5 to 15 mm, or alternatively 1 to 12 mm, or alternatively 2 to 10 mm. When the superimposed multiple sheet-like materials include multiple porous sheet-like materials, the multiple porous sheet-like materials may have the same thickness or different thicknesses.

[0018] The density of the porous sheet material is 10 to 250 kg / m from the viewpoint of excellent sound absorption characteristics in the low frequency range. ３and 20 to 200 kg / m ３ and 30 to 150 kg / m ３ When the stacked sheet-like materials include a plurality of porous sheet-like materials, the porous sheet-like materials may have the same density or different densities.

[0019] From the viewpoint of excellent sound absorption characteristics in the low frequency range, the airflow resistance of the porous sheet-like material can be 0.003 to 2.0 kPa·s / m, or alternatively 0.030 to 1.75 kPa·s / m, or alternatively 0.05 to 1.50 kPa·s / m. When the stacked sheet-like materials include a plurality of porous sheet-like materials, the plurality of porous sheet-like materials may have the same airflow resistance or different airflow resistances.

[0020] From the viewpoint of achieving excellent sound absorption characteristics in the low frequency range, the compressive elastic modulus of the porous sheet material can be 0.001 to 5.0 MPa, or alternatively, 0.002 to 2.0 MPa, 0.003 to 1.0 MPa, or 0.010 to 0.50 MPa. When the superposed multiple sheet materials include multiple porous sheet materials, the multiple porous sheet materials may have the same compressive elastic modulus or different compressive elastic moduli.

[0021] In this specification, the compressive modulus of a sheet-like material is determined by the following procedure. First, a sheet-like material is cut into 20 mm x 20 mm pieces to prepare a measurement sample. The thickness of the measurement sample is measured using a vernier caliper. A small tabletop testing machine (Shimadzu Corporation, EZ-Test) is used as the measurement device. A 500 N load cell is used. Stainless steel upper and lower compression platens (φ30 mm) and (φ118 mm) are used as compression measurement jigs. Measurements are performed by placing the measurement sample between the upper and lower compression platens arranged in parallel, with the thickness direction of the measurement sample perpendicular to the upper and lower compression platens, at a speed of 5.0 mm / min, a measurement temperature of 25°C, and in compression mode. The compressive modulus is calculated from the stress-strain curve. Here, strain ε is calculated using the following formula: ε = Δd / d1 In the formula, Δd represents the displacement (mm) of the thickness of the measurement sample due to the load, and d1 represents the thickness (mm) of the measurement sample before the load is applied. The compressive stress σ (MPa) can be calculated using the following formula: σ = F / A In the formula, F represents the compressive force (N), and A represents the cross-sectional area (mm) of the measurement sample before the load is applied. ２ ) The compressive modulus E (MPa) is calculated from the slope of the stress-strain curve between 20% and 30% strain using the following formula: E = (σ2 - σ1) / (ε2 - ε1) In the formula, ε2 indicates a compressive strain of 30%, ε1 indicates a compressive strain of 20%, σ1 indicates the compressive stress measured at compressive strain ε1, and σ2 indicates the compressive stress measured at compressive strain ε2.

[0022] Examples of sheet-like materials other than porous sheet-like materials include resin films.

[0023] Examples of resins constituting the resin film include polyolefin resins such as polyethylene (low density or high density), polypropylene, copolymerized polyethylene, and copolymerized polypropylene; polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; polyamide resins, polyether resins, polyurethane resins, polyacrylic resins, vinyl chloride resins, chlorinated polyethylene resins, silicone resins, polycarbonate resins, synthetic rubber, natural rubber, and modified resins thereof. The resin film may contain one or more of these. From the viewpoints of thinning for weight reduction, heat resistance, durability, and the like, the resin film may contain at least one selected from the group consisting of polyolefin resins, polyester resins, and polyurethane resins.

[0024] From the viewpoint of excellent sound absorption characteristics in the low frequency range, the thickness of the resin film can be 0.5 to 500 mm, or may be 5 to 250 mm, or may be 10 to 150 mm. When multiple resin films are included in multiple overlapping sheet-like materials, the multiple resin films may have the same thickness or different thicknesses.

[0025] The resin film may have a metal vapor-deposited layer on its surface from the viewpoint of improving the sound absorption effect by adjusting the film properties and imparting a heat ray reflection function. The metal vapor-deposited layer can be formed by physical vapor deposition such as vacuum deposition or chemical vapor deposition of a metal such as aluminum, copper, zinc, a zinc alloy, or silver. The metal vapor-deposited layer may be provided on both sides or on one side of the resin film.

[0026] The resin film may be a perforated film from the viewpoint of improving the sound absorption effect in the low frequency range and adjusting the sound absorption frequency peak. The perforated film may have holes arranged in a lattice or diamond shape. From the viewpoint of excellent sound absorption characteristics in the low frequency range, the holes may be circular with a diameter of 0.1 to 50.0 mm, 0.2 to 10.0 mm, or 0.3 to 5.0 mm. The shape of the holes may be circular, elliptical, rectangular, polygonal, etc.

[0027] The stacked multiple sheet-like materials may include a sheet-like material having a thickness of 0.01 mm or more and less than 0.5 mm (hereinafter also referred to as an "intermediate layer-forming sheet-like material"). Such a sheet-like material can form an intermediate layer in the resulting sound-absorbing material, which can improve the sound absorption performance in the low frequency range, as well as improve durability and strength. When the stacked multiple sheet-like materials include the intermediate layer-forming sheet-like material, the thickness of the porous sheet-like material may be 0.5 mm or more.

[0028] The intermediate layer-forming sheet may be made of the same material as the porous sheet described above, or may be a nonwoven fabric from the viewpoint of improving sound absorption performance in the low frequency range. Furthermore, the intermediate layer-forming sheet may be made of the same material as the resin film described above from the viewpoint of improving durability.

[0029] The thickness of the intermediate layer-forming sheet material can be 0.01 mm or more and less than 0.5 mm, and may be 0.02 to 0.3 mm, or may be 0.05 to 0.2 mm, from the viewpoint of processability such as lamination. When the overlapped sheet materials include a plurality of intermediate layer-forming sheet materials, the plurality of intermediate layer-forming sheet materials may have the same thickness or different thicknesses.

[0030] When the intermediate layer-forming sheet-like material is a porous body, its airflow resistance can be 0.01 kPa·s / m or more, and may be 0.01 to 10 kPa·s / m, 0.1 to 7 kPa·s / m, 0.25 to 5 kPa·s / m, or 0.5 to 2 kPa·s / m, from the viewpoint of improving sound absorption performance in the low frequency range. When the overlapped sheet-like materials include a plurality of porous intermediate layer-forming sheet-like materials, the plurality of intermediate layer-forming sheet-like materials may have the same airflow resistance or different airflow resistances.

[0031] Examples of adhesive components of the adhesive include vinyl acetate resin, polyolefin resin, ethylene-vinyl acetate copolymer resin, isobutene-maleic anhydride copolymer resin, acrylic copolymer resin, acrylic monomer, acrylic oligomer, styrene-butadiene rubber, vinyl chloride resin, chloroprene rubber, nitrile rubber, urethane resin, silylated urethane resin, epoxy resin, modified epoxy resin, polyethylene resin, ionomer resin, silicone resin, modified silicone resin, water glass, silicate, etc. From the viewpoint of adhesive handling and durability, the adhesive may contain at least one adhesive component selected from the group consisting of polyolefin-based resin, polyester-based resin, polyurethane-based resin, acrylic resin, and silicone-based resin. The adhesive may also be a layer containing the above adhesive component, or a laminate (e.g., double-sided tape) having layers containing the above adhesive component on both sides of a support made of paper, cloth, resin film, metal tape, etc. Each adhesive layer may be made of the same material or different materials.

[0032] When a plurality of adhesives are present between a plurality of overlapping sheet-like materials, the plurality of adhesives may be composed of the same adhesive component or may be composed of different adhesive components.

[0033] The adhesive may be a hot melt adhesive from the viewpoints of controlling the amount of application and durability. Examples of hot melt adhesives include ethylene vinyl acetate copolymer-based, polyolefin-based, polyamide-based, synthetic rubber-based, acrylic-based, polyurethane-based, and polyester-based adhesives.

[0034] The adhesive may have a viscosity at 120°C of 0.1 to 30 Pa·s, 1 to 20 Pa·s, or 2 to 15 Pa·s.

[0035] The thickness of the adhesive can be 0.1 to 500 μm, and may be 1 to 200 μm. When multiple adhesives are present between multiple overlapping sheet-like materials, the multiple adhesives may have the same thickness or different thicknesses.

[0036] The adhesive coating weight is 1 to 300 g / m２ and 10 to 150 g / m ２ When a plurality of adhesives are present between a plurality of overlapping sheet-like materials, the plurality of adhesives may have the same coating weight or different coating weights.

[0037] The adhesive may be applied by spray coating or transfer using a roll coater. For example, the adhesive may be spray coated onto the main surface of the sheet-like material before lamination, or may be transferred using a roll coater. The viscosity of the adhesive during application or transfer may be 0.1 to 30 Pa·s, or may be 1 to 20 Pa·s, or may be 2 to 15 Pa·s. The viscosity of the adhesive may be adjusted by a solvent. The solvent may be water, an organic solvent, or a mixed solvent containing water and an organic solvent. The organic solvent is not particularly limited as long as it can adjust the viscosity of the adhesive, and examples include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, and p-cymene; aliphatic hydrocarbons such as hexane, heptane, and pentane; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol, and propylene glycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; and amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0038] The adhesive may be provided over the entire area of ​​the main surface of the sheet-like material, or from the viewpoint of achieving both durability, sound absorption characteristics, and weight reduction of the sound-absorbing material, it may be provided over a range of 1 to 99%, 5 to 70%, or 10 to 50% of the area of ​​the main surface of the sheet-like material. The adhesive may be provided in the form of a mist, web, spiral, dot, line, or other shape, or may be provided in a predetermined pattern.

[0039] The total thickness of the multiple sheet-like materials superimposed with an adhesive can be 3 to 35 mm, and from the viewpoint of durability, it may be 25 mm or less, or 15 mm or less, and from the viewpoint of sound absorption performance, it may be 4 mm or more, or 5 mm or more.

[0040] The laminated sheet-like materials may be formed, for example, by supplying the sheets from a plurality of unwinding devices to a roll press device. In this case, a step of applying or transferring adhesive to some or all of the laminated sheet-like materials may be provided so that the adhesive is interposed between the laminated sheet-like materials. The adhesive may be applied to one or both surfaces of the laminated sheet-like materials.

[0041] In the method for producing a sound-absorbing material of this embodiment, multiple overlapping sheet-like materials can be compressed so that the thickness of at least one of the porous sheet-like materials in the compressed body (hereinafter also referred to as the "post-compression thickness") is 70 to 99% of the thickness before compression. The post-compression thickness of the porous sheet-like material can be adjusted to the above range by appropriately setting the pressure and temperature during compression, as well as the compression ratio of the multiple overlapping sheet-like materials described below, depending on the physical properties of the sheet-like material.

[0042] The thickness after compression may be checked immediately after compression, or after 10 to 600 seconds have elapsed since compression, or after 60 seconds have elapsed.

[0043] Examples of means for compressing a plurality of sheet-like materials superposed with an adhesive include a press device equipped with a laminating roll, a press device equipped with a press conveyor, and a press device in which a line and a press are connected.

[0044] From the viewpoint of achieving both sound absorption performance and durability, the thickness after compression may be 80 to 99% or 85 to 95% of the thickness before compression, and the compression step may be carried out so that the thickness after compression of all porous sheet-like materials satisfies the above-mentioned condition.

[0045] In the compression step, the compression ratio in the thickness direction of the stacked multiple sheet-like materials can be 10% to 90%, and from the viewpoints of reducing wrinkles during lamination, reducing warping of the compressed body, and improving durability by ensuring adhesive strength, it may be 20% to 80%, or may be 30% to 70%. The compression ratio can be adjusted by appropriately setting the lamination gap of the roll press device (e.g., the distance between a pair of rolls, the distance between a roll and a conveyor belt, etc.) or the lamination pressure of the lamination roll.

[0046] In the compression step, the stacked sheets may be compressed at a temperature of 10 to 200° C. or 15 to 150° C. In this case, the sheets may be compressed after being heated in a heating furnace or the like, or may be heated simultaneously with compression using a heat roll, a conveyor, a hot plate press, or the like.

[0047] In the compression step, the stacked sheet-like materials may include a structure in which a porous sheet-like material and a resin sheet are stacked via an adhesive. In this case, the resulting compressed material can incorporate a structure in which a resin layer derived from a resin sheet that can exert a membrane vibration sound-absorbing effect that forms a sound absorption peak frequency in the low frequency range and a porous layer derived from a porous sheet-like material that exerts a sound energy attenuation effect are bonded with sufficient adhesive strength, making it easy to further improve the sound absorption performance of the sound-absorbing material in the low frequency range.

[0048] The stacked sheets may also include a structure in which porous sheet-like materials are stacked together with an adhesive. In this case, in addition to obtaining a further sound energy attenuation effect, a damping effect can also be obtained at the interface between the sheet-like materials, making it easier to improve sound absorption performance in the low frequency range while achieving a thinner product.

[0049] Furthermore, the multiple overlapping sheet-like materials may include a structure in which a resin film, a porous sheet-like material, and another porous sheet-like material are overlapped in this order via an adhesive. In this case, it is possible to obtain the effect achieved by the structure in which a resin film and a porous sheet-like material are overlapped via an adhesive, and the effect achieved by the structure in which a porous sheet-like material and another porous sheet-like material are overlapped via an adhesive, and it becomes easy to further improve the sound absorption performance of the sound-absorbing material in the low frequency range.

[0050] In the method for producing a sound-absorbing material of this embodiment, the compressed body obtained through the compression step may be used as the sound-absorbing material as is, or the compressed body may be further laminated with another sheet-like material (for example, the sheet-like material or compressed body described above, or a substrate such as a resin plate or a metal plate) to form a sound-absorbing material, which may be molded into a predetermined shape. The compressed body may have a porous layer derived from the porous sheet-like material, a resin layer derived from the resin film, and an adhesive layer derived from the adhesive.

[0051] In the compression step, the stacked sheet-like materials may include a compressed body obtained in the same manner as in the compression step. That is, the method of the present embodiment includes two or more compression steps, and the stacked sheet-like materials in the subsequent compression step may include a compressed body obtained in the previous compression step. In this case, the thickness after compression in the subsequent compression step can be measured using the thickness of the uncompressed porous sheet-like materials.

[0052] The method for producing the sound-absorbing material of this embodiment may be a roll-to-roll method or a roll-to-sheet method.

[0053] 1 and 2 are schematic diagrams for explaining the compression step in the method for manufacturing a sound-absorbing material.

[0054] In the compression step shown in Fig. 1, the porous sheet-like material 10 and the resin film 30, which are conveyed and superposed with the adhesive 20 interposed therebetween, are compressed by a pair of laminating rolls 50 to obtain a compressed body 100. By this step, the thickness T １０ is compressed to a thickness 10a, and the compressed porous sheet-like material 10a and the resin film 30 are bonded together by an adhesive 20a.

[0055] In the compression step shown in FIG. 1, the thickness T of the porous sheet-like material in the compressed body 100 １０ａ is the thickness before compression T １０ The thickness is 70 to 99% of the thickness T １０ａ is the thickness T １０ It may be 80 to 99%, or 85 to 95% of the total.

[0056] In the compression step shown in FIG. 1, the compression ratio (T ｙ１ x 100 / T ｘ１ ) can be 10% to 90%, and from the viewpoints of reducing wrinkles during lamination, reducing warping of the compressed body, and improving durability by ensuring adhesive strength, it may be 20 to 80%, or 30 to 70%.

[0057] In the compression step shown in Fig. 2, the porous sheet-like material 10 and the porous sheet-like material 12, which are conveyed and superposed with the adhesive 22 interposed therebetween, are compressed by a pair of laminating rolls 50 to obtain a compressed body 101. By this step, the thickness T １０ , T １２ But the thickness T １０ａ , T １２ａ The compressed porous sheet-like material 10a and the porous sheet-like material 12a are bonded together by adhesive 22a.

[0058] In the compression step shown in FIG. 2, the thickness of at least one of the porous sheets 10b and 12b in the compressed body becomes 70 to 99% of the thickness before compression. １０ａ x 100 / T１０ , T １２ａ x 100 / T １２ , or both of these may be 70 to 99%, 80 to 99%, or 85 to 95%.

[0059] In the compression step shown in FIG. 2, the compression ratio (T ｙ２ x 100 / T ｘ２ ) can be 10% to 90%, and from the viewpoint of reducing warping of the compressed body and improving durability by ensuring adhesive strength, it may be 20 to 80%, or 30 to 70%.

[0060] In the compression step shown in FIGS. 1 and 2, a roll press device equipped with a pair of laminating rolls 50 is used, but a press device equipped with laminating rolls and a conveyor belt may also be used.

[0061] 3A and 3B are schematic diagrams showing an example of the structure of a sound-absorbing material that can be obtained by the method for producing a sound-absorbing material of this embodiment. The sound-absorbing material 110 shown in Fig. 3A has a structure in which a resin layer 30c derived from a resin film, a first adhesive layer 20c derived from an adhesive, and a porous layer 10c derived from a porous sheet-like material are laminated in this order. The sound-absorbing material 110 can be formed from a compressed body obtained through the compression step shown in Fig. 1.

[0062] The sound-absorbing material 120 shown in Fig. 3(b) has a structure in which a first porous layer 10c derived from a porous sheet-like material, a second adhesive layer 22c derived from an adhesive, and a second porous layer 12c derived from a porous sheet-like material are laminated in this order. The sound-absorbing material 120 can be made from a compressed body obtained through the compression process shown in Fig. 2.

[0063] 4 to 6 are schematic diagrams showing examples of the structure of a sound-absorbing material that can be obtained by the method for producing a sound-absorbing material according to this embodiment.

[0064] The sound-absorbing material 200 shown in Fig. 4(a) has a structure in which a resin layer 30c derived from a resin film, a first adhesive layer 20c derived from an adhesive, a first porous layer 10c derived from a porous sheet-like material, a second adhesive layer 22c derived from an adhesive, and a second porous layer 12c derived from a porous sheet-like material are laminated in this order. The sound-absorbing material 201 shown in Fig. 4(b) has a structure in which a resin layer 30c derived from a resin film, a first adhesive layer 20c derived from an adhesive, a first porous layer 10c derived from a porous sheet-like material, a second adhesive layer 24c derived from an adhesive, an intermediate layer 40c derived from an intermediate layer-forming sheet-like material, a third adhesive layer 26c derived from an adhesive, and a second porous layer 12c derived from a porous sheet-like material are laminated in this order.

[0065] The sound-absorbing material 202 shown in Fig. 5(a) has a structure in which a third porous layer 14c derived from a porous sheet-like material is further laminated, via a third adhesive layer 28c derived from an adhesive, on the resin layer 30c derived from a resin film in the sound-absorbing material 200 shown in Fig. 4(a). The sound-absorbing material 203 shown in Fig. 5(b) has a structure in which a third porous layer 14c derived from a porous sheet-like material is further laminated, via a third adhesive layer 28c derived from an adhesive, on the resin layer 30c derived from a resin film in the sound-absorbing material 201 shown in Fig. 4(b).

[0066] The sound-absorbing material 204 shown in Fig. 6(a) has a structure in which a second resin layer 32c derived from a resin film is further laminated via a third adhesive layer 28c derived from an adhesive onto the second porous layer 12c derived from a porous sheet-like material in the sound-absorbing material 200 shown in Fig. 4(a). The sound-absorbing material 205 shown in Fig. 6(b) has a structure in which a second resin layer 32c derived from a resin film is further laminated via a third adhesive layer 28c derived from an adhesive onto the second porous layer 12c derived from a porous sheet-like material in the sound-absorbing material 201 shown in Fig. 4(b).

[0067] 4 to 6, all layers may be formed in a single compression step, or when there are multiple porous layers derived from a porous sheet-like material, the porous layers may be provided in multiple compression steps. Also, a resin film may be bonded to the compressed body obtained in the compression step with an adhesive, or compressed bodies obtained in the compression steps may be bonded to each other with an adhesive.

[0068] For example, in the case of the sound-absorbing material 200, it may be formed from a compressed body obtained by compressing a resin film, a porous sheet-like material, and a porous sheet-like material that are superimposed via an adhesive under the conditions of the compression process described above.As shown in Figure 7, it may be formed by obtaining a compressed body having a structure in which a first porous layer 10c derived from a porous sheet-like material, a second adhesive layer 22c derived from an adhesive, and a second porous layer 12c derived from a porous sheet-like material are laminated by the compression process described above, and then joining the obtained compressed body and a resin film via an adhesive.

[0069] The method shown in Figure 7 is a roll-to-roll manufacturing method that includes step A of applying adhesive by spray 60 to the surface of sheet-like material 12, which is a porous material, supplied from unwinding device 54; step B of overlapping sheet-like material 10, which is a porous material, supplied from unwinding device 54, on the side of sheet-like material 12 on which adhesive 22 is provided, and compressing them with a pair of laminating rolls 50 to obtain compressed body 102; step C of applying adhesive by spray 60 to the surface of the porous layer side of compressed body 102 derived from sheet-like material 10, which is a porous material; step D of overlapping resin film 30, which is supplied from unwinding device 58, on the side of compressed body 102 on which adhesive 20 is provided, and bonding them with the pair of laminating rolls 50 to obtain sound-absorbing material 200; and step E of winding up sound-absorbing material 200 with winding device 70.

[0070] In this method, the above-described compression process can be applied to step B (the portion surrounded by the dashed line P1 in FIG. 7).

[0071] 7 includes a series of steps A, B, C, D, and E, but winding up of an intermediate body may be performed in between. For example, the sound-absorbing material may be produced through the following steps: Step A1 of applying an adhesive by spraying to the surface of a porous sheet-like material supplied from an unwinding device; Step B1 of overlapping a porous sheet-like material supplied from another unwinding device on the adhesive side of the sheet-like material and compressing them with a pair of laminating rolls to obtain a compressed body; Step E1 of winding up the compressed body with a winding device to obtain a roll of compressed body as an intermediate body; Step C1 of applying an adhesive by spraying to the surface of the porous layer derived from the porous sheet-like material of the compressed body supplied from the roll obtained in Step E1; Step D1 of overlapping a resin film supplied from another unwinding device on the adhesive side of the compressed body and bonding them with a pair of laminating rolls to obtain a sound-absorbing material; and Step E2 of winding up the sound-absorbing material with a winding device.

[0072] According to the method for producing a sound-absorbing material of the present disclosure, it is possible to obtain a sound-absorbing material having excellent sound-absorbing properties in the low-frequency range. Such a sound-absorbing material can be suitably used in applications such as automobiles, railway vehicles, aircraft, ships, buildings such as houses, electronic devices, precision machinery, and acoustic equipment. The low-frequency range referred to here can be a range of frequencies of 1500 Hz or less, or may be a range of 1000 Hz or less, a range of 800 Hz or less, a range of 750 Hz or less, or a range of 500 Hz or less.

[0073] 10, 12... Porous sheet-like material, 20, 22... Adhesive, 30... Resin film, 50... Laminate roll, 100, 101... Compressed body, 110, 120, 200, 201, 202, 203, 204, 205... Sound-absorbing material.

Claims

1. A method for manufacturing a sound-absorbing material in which a plurality of sheet-like materials are laminated, comprising a compression step of compressing a plurality of sheet-like materials superposed via an adhesive in the thickness direction thereof to obtain a compressed body, wherein the adhesive is provided by spray coating or transfer by a roll coater, at least one of the plurality of sheet-like materials is a porous body, the thickness of at least one of the sheet-like materials that are the porous body in the compressed body is 70 to 99% of the thickness before compression, A method for manufacturing a sound-absorbing material, which is a roll-to-roll method or a roll-to-sheet method.

2. In the compression step, the compression ratio in the thickness direction of the plurality of superposed sheet-like materials is 10% to 90%. The method for manufacturing a sound-absorbing material according to Claim 1.

3. In the compression step, the plurality of superposed sheet-like materials are compressed at a temperature of 10 to 200°C. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

4. The thickness of the sheet-like material that is the porous body is 0.5 to 15 mm. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

5. The density of the sheet-like material that is the porous body is 10 to 250 kg / m3. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

6. The total thickness of the plurality of sheet-like materials superposed via the adhesive is 3 to 35 mm. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

7. The sheet-like material that is the porous body is a non-woven fabric or a resin foam. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

8. At least one of the plurality of sheet-like materials is a resin film containing at least one selected from the group consisting of a polyolefin resin, a polyester resin, and a polyurethane resin. The method for manufacturing a sound-absorbing material according to Claim 1 or 2.

9. In the plurality of superposed sheet-like materials, the manufacturing method of the sound-absorbing material according to claim 8, comprising a structure in which a sheet-like material that is a porous body and a resin sheet are superposed via an adhesive.

10. Two or more of the plurality of sheet-like materials are porous bodies, In the plurality of superposed sheet-like materials, the manufacturing method of the sound-absorbing material according to claim 1 or 2, comprising a structure in which a sheet-like material that is a porous body and a sheet-like material that is a porous body are superposed via an adhesive.

11. Two or more of the plurality of sheet-like materials are porous bodies, At least one of the plurality of sheet-like materials is a resin film containing at least one selected from the group consisting of a polyolefin resin, a polyester resin, and a polyurethane resin, In the plurality of superposed sheet-like materials, the manufacturing method of the sound-absorbing material according to claim 1 or 2, comprising a structure in which a resin film, a sheet-like material that is a porous body, and a sheet-like material that is a porous body are superposed in this order via an adhesive.

12. The manufacturing method of the sound-absorbing material according to claim 1 or 2, wherein the adhesive contains at least one adhesive component selected from the group consisting of a polyolefin-based resin, a polyester-based resin, a polyurethane-based resin, an acrylic-based resin, and a silicone-based resin.

13. The manufacturing method of the sound-absorbing material according to claim 1 or 2, wherein the adhesive is a hot melt adhesive.