WO2023189959A1 - Matériau absorbant acoustique et élément de véhicule - Google Patents

Matériau absorbant acoustique et élément de véhicule Download PDF

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Publication number
WO2023189959A1
WO2023189959A1 PCT/JP2023/011290 JP2023011290W WO2023189959A1 WO 2023189959 A1 WO2023189959 A1 WO 2023189959A1 JP 2023011290 W JP2023011290 W JP 2023011290W WO 2023189959 A1 WO2023189959 A1 WO 2023189959A1
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Prior art keywords
porous layer
absorbing material
sound absorbing
sound
holes
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PCT/JP2023/011290
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English (en)
Japanese (ja)
Inventor
光朗 海野
太希 枝元
圭三 下谷
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株式会社レゾナック
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Publication of WO2023189959A1 publication Critical patent/WO2023189959A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
    • B60R13/08—Insulating elements, e.g. for sound insulation
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials
    • G10K11/168—Plural layers of different materials, e.g. sandwiches
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects

Definitions

  • the present invention relates to sound absorbing materials and vehicle members.
  • a first breathable sound-absorbing layer, a non-breathable resin film layer, and a first breathable sound-absorbing layer are used in order from the passenger compartment side.
  • a soundproofing material in which two air-permeable sound-absorbing layers are bonded in this order is known (for example, see Patent Document 1).
  • a mixture of urethane foam and fiber is used for the first and second air-permeable sound absorbing layers, and a laminate of a plurality of resin films is used for the non-air-permeable resin film layer.
  • a sound-absorbing felt with a gradient air flow resistance value which has a high air flow resistance value part and a low air flow resistance value part between the layers (for example, patented (See Reference 2).
  • the conventional technology still has room for improvement in terms of exhibiting excellent sound absorption characteristics in a wide frequency band even with a thin thickness. Expectations for such improvements are particularly noticeable in sound absorbing materials for vehicles such as automobiles.
  • the present invention has been made in view of the above circumstances, and aims to provide a new sound absorbing material that can exhibit excellent sound absorbing properties in a wide frequency band even if it is thin. Another object of the present invention is to provide a vehicle member including the sound absorbing material.
  • One aspect of the present invention includes a porous layer made of a non-breathable material and a porous layer made of a breathable material, the porous layer having a base having a plurality of pores and at least a portion of the porous layer having a plurality of pores. and a hollow neck extending from the hole into the porous layer, and when the porous layer side is placed facing the target member, two types with different resonance frequencies resonate with sound incident from the hole.
  • a sound absorbing material in which the above Helmholtz resonance box structure is formed. Such a sound absorbing material has an unprecedented structure and can exhibit excellent sound absorbing characteristics in a wide frequency band even if it is thin.
  • the Helmholtz resonant box structure may include a Helmholtz resonant box structure with a resonant frequency of less than 2000 Hz, and a Helmholtz resonant box structure with a resonant frequency of 2000 Hz or more.
  • the Helmholtz resonant box structure includes a Helmholtz resonant box structure with a resonant frequency less than 2000 Hz, a Helmholtz resonant box structure with a resonant frequency between 2000 and 3000 Hz, and a Helmholtz resonant box structure with a resonant frequency greater than 3000 Hz. good.
  • adjacent Helmholtz resonant box structures may have different resonant frequencies.
  • the sound absorbing material may include, in this order, a porous layer, a porous layer, and a backing layer made of a non-breathable material.
  • the aperture ratio of the base may be 1 to 20%.
  • the thickness of the sound absorbing material may be 15 mm or less.
  • the porous layer may contain rubber, and the porous layer may contain nonwoven fabric.
  • the porous layer may include a composite material including rubber and nonwoven fabric.
  • the porous layer may have an air permeability resistance of 1 to 4 kPa ⁇ sec/m.
  • One aspect of the present invention provides a vehicle member including the above sound absorbing material.
  • the present invention it is possible to provide a new sound absorbing material that can exhibit excellent sound absorbing properties in a wide frequency band even if it is thin. Further, according to the present invention, a vehicle member including the sound absorbing material can be provided.
  • FIG. 1 is a schematic cross-sectional view of a sound absorbing material according to one embodiment.
  • FIG. 2 is a schematic cross-sectional view of a sound absorbing material according to another embodiment.
  • FIG. 3 is a schematic cross-sectional view of a sound absorbing material according to another embodiment.
  • FIG. 4 is a schematic cross-sectional view of a sound absorbing material according to another embodiment.
  • FIG. 5 is a schematic cross-sectional view of a sound absorbing material according to another embodiment.
  • FIG. 6 is a diagram schematically showing the arrangement of holes in the sound absorbing material.
  • FIG. 7 is a diagram showing a method of calculating the resonance frequency of the Helmholtz resonance box structure.
  • the term "process” is used not only to refer to an independent process, but also to include any process that achieves the intended effect even if it cannot be clearly distinguished from other processes. It will be done.
  • the term "layer” includes not only a structure formed on the entire surface but also a structure formed on a part of the layer when observed in a plan view.
  • a numerical range indicated using "-" indicates a range that includes the numerical values written before and after "-" as the minimum and maximum values, respectively.
  • the upper limit or lower limit of the numerical range of one step may be replaced with the upper limit or lower limit of the numerical range of another step.
  • the upper limit or lower limit of the numerical range may be replaced with the value shown in the Examples.
  • FIG. 1 is a schematic cross-sectional view of a sound absorbing material according to one embodiment.
  • the sound absorbing material 10 includes a porous layer 1 made of a non-breathable material and a porous layer 2 made of a breathable material, and the porous layer 1 has a plurality of holes h (planar ) A hollow neck portion 1b extending into the porous layer 2 from at least some of the holes h.
  • the porous layer 1 may include a hollow neck portion 1b extending into the porous layer 2 from all the holes h.
  • the porous layer 2 has pores communicating with the pores h and having the same depth as the extension length of the neck portion 1b into the porous layer 2.
  • the space inside the hole h may be a cavity or may be filled with a porous material described below.
  • the sound absorbing material 10 can be used by arranging the porous layer 1 side on the sound incident side and the porous layer 2 side on the other member (object member) side from which sound is to be absorbed.
  • the sound absorbing material 10 and the target member may or may not be in contact with each other.
  • the target parts may be made of non-breathable materials, and specific examples include automobile parts, particularly body panels such as wheel house panels, door panels, and floor panels, and cover parts such as undercovers and wheel house covers. Can be mentioned.
  • the target member may be made of a breathable material.
  • the sound absorbing material 10 can also be called a sound absorbing property improving member from the viewpoint of improving the sound absorbing properties of other members. Further, a structure including the sound absorbing material 10 and the target member can also be referred to as a sound absorbing structure.
  • a Helmholtz resonance box structure When the sound absorbing material 10 is placed with the porous layer 2 side facing the target member, a Helmholtz resonance box structure is formed that resonates with sound incident from the holes h.
  • the hollow neck portion 1b extending within the porous layer 2 allows the resonance frequency of the pores h to be reduced, making it easier to obtain low-frequency sound absorption performance.
  • the sound absorbing material 10 has two or more types of Helmholtz resonance box structures having different resonance frequencies. It is thought that sound (acoustic energy) incident from the porous layer 1 side undergoes Helmholtz resonance within the sound absorbing material 10 and is dissipated as thermal energy. As a result, sound attenuation is observed.
  • FIGS. 2 to 5 are schematic cross-sectional views of sound absorbing materials according to other embodiments.
  • the sound absorbing materials shown in FIGS. 2 to 4 are provided with a backing layer made of a non-breathable material on the entire surface opposite to the sound incident side.
  • the Helmholtz resonance box structure can be formed independently without arranging the target member as described above.
  • the sound absorbing material 11 includes a porous layer 1, a porous layer 2, and a backing layer 3 made of a non-breathable material in this order.
  • the sound absorbing material 12 includes, in this order, a porous layer 1, a porous layer 2, and a backing layer 3 made of a non-breathable material.
  • the porous layer 2 has holes (through holes) communicating with the holes h and having the same depth as the thickness of the porous layer 2.
  • the sound absorbing material 13 includes, in this order, a porous layer 1, a porous layer 2, and a backing layer 3 made of a non-breathable material.
  • the sound absorbing material 14 includes a porous layer 1, a porous layer 2, and a backing layer 3 made of a non-breathable material in this order.
  • the porous layer 2 has holes (through holes) that communicate with the holes h and have the same depth as the thickness of the porous layer 2, and the lining layer 3 also communicates with these holes. It has a hole.
  • the thickness of the sound-absorbing material can be 5 mm or more from the viewpoint of sound-absorbing performance, and may be 8 mm or more, and since it has excellent sound-absorbing properties even with a thin thickness, it can be 30 mm or less, and 25 mm or less. 20 mm or less, 15 mm or less, 13 mm or less, or 12 mm or less.
  • the porous layer and the end faces of the porous layer may be exposed, or the end faces of the porous layer may be covered with a material (covering material) for forming the porous layer.
  • a material covering material
  • the porous layer is constructed from a non-breathable material.
  • the porous layer is a non-air permeable layer, that is, the non-air permeable layer refers to a layer with few continuous pores and high air permeability resistance.
  • the non-permeable layer may be a layer in which continuous pores extending from the sound wave incidence side to the side opposite to the sound wave incidence side account for 10% or less by area when the cross section of the layer is observed.
  • the specific method for confirming continuous pores is as follows. That is, the porous layer to be observed is cast using epoxy resin for embedding (product name Epomount 27-771, 27-772, manufactured by Refinetech Co., Ltd.), and a diamond cutter is used to cut the surface of the porous layer. The cutting process is performed perpendicular to and passing through the center of the pores on the surface of the porous layer. The cut cross section is polished using a liquid compound (product name L120P, manufactured by Sankyo Corporation), and the cross section is observed using a digital microscope (product name VHX-100F, manufactured by Keyence Corporation).
  • the non-air permeable material constituting the porous layer is not limited as long as it has a high air permeability resistance as confirmed above, and includes, for example, plastic, rubber, metal, and composite materials thereof.
  • the base may be made of these materials, such as a thin film with a thickness of less than 200 ⁇ m, a soft sheet with a thickness of 200 ⁇ m or more, a rigid plate with a thickness of more than 1 mm (perforated film, perforated sheet, perforated sheet, etc., respectively). (can be called a board, etc.).
  • the neck portion may be formed using these materials, or may be formed using a tube or the like made of these materials.
  • the non-breathable material constituting the porous layer include rubber or a composite material containing rubber and nonwoven fabric. Due to the manufacturing process of the sound absorbing material, the porous layer (base and neck portion) may include a material that is a composite of the material forming the porous layer and the porous material, for example, a composite material containing rubber and nonwoven fabric. . The porous layer may be composed of the composite material.
  • Plastics include polyesters such as polyethylene terephthalate (PET), polyolefins such as polypropylene (PP), high density polyethylene (HDPE), and low density polyethylene (LDPE), ethylene-vinyl acetate copolymer resin (EVA), ABS, AES, Examples include ASA, polyphenylene ether (PPE), and the like. Rubbers include urethane rubber (PU), silicone rubber, natural rubber (NR), butyl rubber, styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene diene rubber (EPDM), and fluorine rubber. Examples include rubber (FKM).
  • PET polyethylene terephthalate
  • PP polypropylene
  • HDPE high density polyethylene
  • LDPE low density polyethylene
  • EVA ethylene-vinyl acetate copolymer resin
  • ABS AES
  • Rubbers include urethane rubber (PU), silicone rubber,
  • Examples of metals include stainless steel, aluminum, and copper.
  • Examples of the composite material include fiber reinforced rubber (FRR) and fiber reinforced plastic (FRP).
  • the material for forming the porous layer is preferably rubber or plastic from the viewpoint of workability when integrating with the porous layer as a molded product with a complex shape, and the material is preferably rubber or plastic, which is applied to the porous layer and dried.
  • Natural rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, and chloroprene rubber can be used in the form of latex from the viewpoint that it is possible to easily form a non-breathable layer (a layer that becomes a porous layer) on a porous layer. Rubbers such as , urethane rubber, and fluororubber are more preferred.
  • the thickness of the base can be 50 ⁇ m or more, and may be 100 ⁇ m or more, from the viewpoint of durability, and can be 5 mm or less, and 2 mm or less, from the viewpoint of weight reduction, thinning, etc. There may be.
  • the thickness of the base can be measured as follows. That is, the base to be observed is cast using an embedding epoxy resin, and cut using a diamond cutter so that the diamond cutter is perpendicular to the surface of the porous layer. The cut cross section is polished using a liquid compound, and the cross section is observed using a digital microscope. Measure the thickness of the base from the cross-sectional observation photograph.
  • the aperture ratio of the base can be 1% or more, from the viewpoint of sufficiently injecting sound waves into the sound absorbing material, and may be 2% or more, and from the viewpoint of suitably generating Helmholtz resonance, it is 20% or less. It may be 15% or less.
  • the aperture ratio can be calculated by dividing the area of the pores when the porous layer of the sound absorbing material is viewed from the thickness direction by the area of the porous layer (base).
  • the shape of the hole in the base may be circular, elliptical, rectangular, polygonal, irregular, etc., and any shape suitable for adjusting the opening ratio and convenience of the construction method can be adopted. By adjusting the hole diameter, pitch, etc., the resonance frequency during sound absorption can be adjusted.
  • the shape of the hole is preferably circular from the viewpoint of workability.
  • the diameter of the hole that is, the inner diameter of the hollow neck part
  • the diameter of the pores can be measured as follows. That is, the base to be observed is cast using an embedding epoxy resin, and cut using a diamond cutter so that the diamond cutter is perpendicular to the surface of the porous layer and passes through the center of the hole on the surface of the base. The cut cross section is polished using a liquid compound, and the cross section is observed using a digital microscope. Measure the hole diameter from the cross-sectional observation photograph. The diameter of the pore is determined as the average value of the measurements for 5 pores.
  • the holes may be arranged in a lattice pattern, such as a rhombic lattice (orthorhombic lattice), hexagonal lattice (triangular lattice), etc., from the viewpoint of obtaining excellent sound absorption properties. They may be arranged in a square lattice shape, a rectangular lattice shape, a distorted oblique lattice shape, etc.
  • the pitch of the holes can be 1 mm or more, and may be 5 mm or more, from the viewpoint of workability, and can be 30 mm or less, and may be 20 mm or less, from the viewpoint of improving the aperture ratio. .
  • the pitch of holes refers to the distance between the centers of adjacent holes, as shown in P in FIG. 6, which will be described later.
  • the hole pitch is determined as the average value of measurements for five holes.
  • the length of the neck portion may be 5% or more of the thickness of the porous layer, may be 10% or more, or may be 30% or more of the thickness of the porous layer, from the viewpoint of further improving sound absorption characteristics. It may be 50% or more.
  • the length of the neck part can be 90% or less of the thickness of the porous layer, from the viewpoint of ensuring a gap between the back surface of the sound absorbing material (the surface opposite to the sound wave incident side) and the tip of the neck part, and 80% of the thickness of the porous layer. % or less.
  • the length of the neck portion is not particularly limited as it varies depending on the thickness of the porous layer, etc., but may be 1 mm or more, may be 3 mm or more, or may be 5 mm or more. Similarly, the length of the neck portion can be 9 mm or less, and may be 8 mm or less.
  • the thickness of the neck portion that is, the difference between the inner diameter and outer diameter of the hollow structure, can be 50 ⁇ m or more, and can be 100 ⁇ m or more, from the viewpoint of making the neck rigid and obtaining better durability against vibration. Good too.
  • the thickness of the neck portion may be 5 mm or less, and may be 2 mm or less, from the viewpoint of ensuring the volume of the porous layer and particularly improving low frequency sound absorption performance.
  • the length and thickness of the neck can be measured by observing the cross section in the same manner as the base described above and from the cross-sectional observation photograph.
  • the length and thickness of the neck are determined as the average value of measurements for five necks.
  • the porous layer and the porous layer may be bonded or integrated. Thereby, it is easy to prevent the porous layer from peeling off from the porous layer due to vibration or the like, or the neck portion from vibrating alone and being damaged. Adhesion or integration of the two may be performed using an adhesive, or may be performed by impregnating at least a portion of the material constituting the porous layer into the porous layer and drying it.
  • an adhesive layer can be provided between the porous layer and the porous layer.
  • the adhesive layer includes 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, and 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, layer containing adhesive components such as silicate, or paper, cloth, resin.
  • Examples include laminates (for example, double-sided tapes) comprising layers containing these adhesive components on both sides of a support made of a film, a metal tape, or the like.
  • the thickness of the adhesive is not particularly limited, but may be 0.01 to 500 ⁇ m, and may be 1 to 250 ⁇ m.
  • the porous layer (base and neck) can include a composite material including, for example, rubber and non-woven fabric.
  • the porous layer may include, for example, a composite material layer (composite material layer) on the porous layer side, or may be a composite material layer.
  • Examples of the advantages of using such a composite material as the porous layer include the following. - By adjusting the solid content concentration of the latex rubber solution to be impregnated, the amount of rubber can be partially increased or decreased, making it easy to control the structure of the non-porous layer/porous layer. ⁇ Excellent durability as the non-ventilated layer and ventilated layer are strongly integrated. - The ventilation resistance of the ventilation layer can be controlled by the amount of rubber, making it easy to adjust sound absorption performance and density. - Vibration damping effect can be imparted due to the viscoelasticity of rubber.
  • the porous layer is composed of a breathable material.
  • the porous layer refers to a layer containing an air-permeable porous material, and specifically refers to a layer having an air-flow resistance of 4 kPa ⁇ sec/m or less.
  • the ventilation resistance of the porous layer may be 1 kPa sec/m or more, and may be 2 kPa sec/m or more, from the viewpoint of easily maintaining the viscosity loss due to air of the sound wave incident on the porous layer. Further, from the viewpoint of making it easier for sound waves to enter the porous layer, the pressure can be set to 4 kPa ⁇ sec/m or less, and may be 3 kPa ⁇ sec/m or less.
  • the specific method for checking ventilation resistance is as follows.
  • the porous layer may be obtained by mechanically removing the porous layer from the sound absorbing material.
  • the curved surface can be transformed into a flat surface for measurement.
  • the breathable material constituting the porous layer is not limited as long as it is a material with low ventilation resistance as confirmed above, and includes nonwoven fabrics, foams, and the like.
  • nonwoven fabric examples include nonwoven fabrics made of fibers such as glass, silica, rock wool, and plastics (PET, PP, nylon, cellulose, natural fibers, or composites thereof).
  • PET glass, silica, rock wool, and plastics
  • PP polypropylene
  • nylon polypropylene
  • cellulose polymethyl methacrylate
  • natural fibers or composites thereof.
  • the nonwoven fabric it is also possible to use a nonwoven fabric that contains a binder and can be shaped, and a nonwoven fabric that contains inorganic particles, elastomer, rubber, etc. and has adjusted ventilation resistance.
  • the foam include urethane foam, polyethylene foam, melamine foam, rubber sponge (rubber foam), and the like.
  • the porous layer can include a composite material that includes a porous material and rubber.
  • the porous material and rubber can be combined by impregnating the porous material with a material containing rubber and drying the impregnated material.
  • the composite of a porous material and rubber may mean, for example, that the surface of a material (fiber) constituting a nonwoven fabric is covered with rubber while maintaining air permeability as a porous layer.
  • the average fiber diameter of the fibers constituting the nonwoven fabric is not particularly limited, but from the viewpoint of obtaining better sound absorption properties, it can be, for example, 1 to 30 ⁇ m, and may be 5 to 15 ⁇ m.
  • the average fiber diameter is determined by taking the average of the fiber diameters of individual fibers measured from photographs taken with an electron microscope at 1000 times magnification. Specifically, the average fiber diameter is determined by measuring the fiber diameters of a total of 100 fibers arbitrarily selected from 10 photographs and averaging them.
  • the thickness of the porous layer can be 5 mm or more, especially from the viewpoint of sound absorption performance at low frequencies, and may be 8 mm or more, and from the viewpoint of applications for automobile parts that require a thin thickness, it can be 15 mm or more. or less, and may be 12 mm or less.
  • the depth of the holes is determined by the extension of the neck from the viewpoint that it is easy to form the neck after drilling the holes.
  • the length may be longer than that, and may be the same as the thickness of the porous layer (the porous layer may have through holes).
  • the porous layer may have no pores, in which case the neck portion may be embedded within the porous layer. That is, the hollow portion of the neck portion may contain (fill) the material of the porous layer.
  • the backing layer is constructed from a non-breathable material.
  • the backing layer can improve the durability, rigidity, etc. of the sound absorbing material.
  • the backing layer may be formed on the entire surface of the porous layer, and may have pores that communicate with the porous layer and the pores of the porous layer.
  • an adhesive sheet or film for adhering to a sound-absorbing object, or a damping sheet or film for imparting vibration damping properties can also be used.
  • the thickness of the backing layer can be 50 ⁇ m or more from the viewpoint of improving durability and rigidity, and may be 100 ⁇ m or more, and from the viewpoint of applications for automobile parts that require thin thickness, It can be 5 mm or less, and may be 2 mm or less.
  • the sound absorbing material can include other layers (sheets, films, etc.) in addition to the porous layer and the porous layer. These other layers can be attached via an adhesive layer or the like.
  • the layer that can be provided on the sound incident side, that is, on the porous layer side is a breathable layer (layer with ventilation resistance of 4 kPa sec/m or less) or a non-breathable layer that the porous layer has. Examples include a layer having holes at the same positions as the holes (a layer that does not prevent sound from entering).
  • a breathable layer can be provided on the side opposite to the sound incident side, that is, on the porous layer side.
  • the breathable layer examples include porous sound absorbing materials (foam, nonwoven fabric, felt, etc.), porous films, etc. for the purpose of improving sound absorption properties, covering pores, improving design, and the like.
  • a non-breathable layer with holes in the same positions as the holes in the porous layer a porous metal plate is used for the purpose of protecting the surface of the sound incident side, improving durability, improving rigidity, improving mechanical strength, etc. , porous plastic sheets, etc.
  • Helmholtz resonance box structure When the sound absorbing material is placed with the porous layer side facing the target member, two or more types of Helmholtz resonance box structures having different resonance frequencies are formed, which resonate with sound incident through the pores of the porous layer. Thereby, the sound absorbing material can exhibit high sound absorbing properties over a wide range from the low frequency side to the high frequency side.
  • the Helmholtz resonance box structure refers to the components of the Helmholtz resonator, namely the opening (pores in the porous layer), the neck (the thickness of the porous layer, or the thickness of the porous layer and the length of the neck), and the body (the porous layer). It has a structure that theoretically functions as a Helmholtz resonance box.
  • the Helmholtz resonance box structure preferably includes a Helmholtz resonance box structure having a resonance frequency of less than 2000 Hz and a Helmholtz resonance box structure having a resonance frequency of 2000 Hz or more, and a resonance frequency less than 2000 Hz. More preferably, the present invention includes a Helmholtz resonant box structure having a resonant frequency of 2000 to 3000 Hz, and a Helmholtz resonant box structure having a resonant frequency of greater than 3000 Hz. In this case, it is more preferable that adjacent Helmholtz resonance box structures have different resonance frequencies. That is, by arranging holes that exhibit different resonance frequencies (holes with different sound absorption frequency classifications) adjacent to each other, it becomes easier for sound waves to diffract and enter the respective holes, making it easier to widen the sound absorption frequency range.
  • FIG. 6 is a diagram schematically showing the arrangement of holes in the sound absorbing material.
  • the figure shows a suitable arrangement of holes A to C that exhibit different resonance frequencies when the porous layer of the sound absorbing material is viewed from the thickness direction.
  • holes A and C are arranged in a square lattice, and holes that exhibit different resonance frequencies are adjacent to each other.
  • holes A to C are arranged in a triangular lattice shape (regular triangular lattice shape), and holes that exhibit different resonance frequencies are adjacent to each of the holes A to C.
  • the same number of holes B and C are adjacent to each other around hole A, and holes A are not adjacent to each other.
  • FIG. 7 is a diagram showing a method for calculating the resonance frequency of the Helmholtz resonance box structure.
  • each portion surrounded by a broken line represents a Helmholtz resonance box unit.
  • the resonant frequency of the Helmholtz resonance box structure that resonates with sound incident through each hole can be adjusted from various dimensions of the sound-absorbing material according to this calculation method.
  • V is the volume of the porous layer when the porous layer is divided into Helmholtz resonance box units.
  • V is a square or rectangle (see the broken line in Figure 6) of the porous layer starting from the center of the adjacent pores and passing through the midpoint between the pores. It is calculated as the volume of a rectangular parallelepiped or cube multiplied by the thickness T. If there are multiple drawing methods when drawing a rectangle that passes through the midpoints of the holes, the drawing is done so that adjacent rectangles do not overlap and their area is maximized.
  • V is a porous polygon whose starting point is the center of the adjacent pores and whose apex is the midpoint between the pores. It is calculated as the volume of a polygonal prism multiplied by the layer thickness T. In either case, if a neck extends within the porous layer, the volume obtained by subtracting the volume of the neck is defined as V.
  • ⁇ is an opening end correction; for example, when the shape of the hole is circular, ⁇ can be calculated as 0.8 times the diameter of the hole. If the shape of the hole is not circular, ⁇ can be calculated as 0.8 times the diameter of a perfect circle having the same area as the hole.
  • a method for manufacturing the sound absorbing material 10 shown in FIG. 1 will be described below, but there is no particular restriction on the method for manufacturing the sound absorbing material.
  • a latex rubber solution with a low solid content concentration and a latex rubber solution with a high solid content concentration are prepared.
  • the amount of solids in a latex rubber solution with a low solids concentration can be 15 to 35% by mass, and the amount of solids in a latex rubber solution with a high solids concentration can be 40 to 70% by mass.
  • Each latex rubber solution can contain one or more of the rubbers listed above. Further, various commonly used additives can be added to each latex rubber solution depending on the purpose. Additives include wetting agents or viscosity modifiers for adjusting the impregnability of nonwoven fabrics, colorants for coloring (carbon black, etc.), and vulcanizing agents (such as sulfur or oxidation agents) for improving heat resistance and durability. Zinc), vulcanization accelerators, anti-aging agents, inorganic fillers (talc or clay), heat-sensitizing materials to improve cohesion and prevent segregation during heat drying, stabilizers to improve solution stability (interfacial activator or pH adjuster), etc.
  • Additives include wetting agents or viscosity modifiers for adjusting the impregnability of nonwoven fabrics, colorants for coloring (carbon black, etc.), and vulcanizing agents (such as sulfur or oxidation agents) for improving heat resistance and durability. Zinc), vulcanization accelerators, anti-aging agents, inorganic fillers (
  • Impregnate the porous layer with a latex rubber solution with a low solid content concentration examples include a method of spraying a latex rubber solution onto the porous layer, a method of immersing the porous layer in a latex rubber solution, and the like. At this time, the amount of latex rubber is adjusted so that the ventilation resistance of the porous layer does not exceed 4 kPa ⁇ sec/m.
  • a nonwoven fabric coated with a latex rubber solution having a low solid content concentration is heated and dried to coagulate and harden the latex rubber. As a result, a porous layer made of a composite material containing nonwoven fabric and rubber is formed.
  • a pointed member (perforating member) is used as necessary to form holes with a desired arrangement and depth in a nonwoven fabric made of agglomerated and hardened latex rubber.
  • the pointed member include a needle pin and a punch.
  • the shape of the pointed member (shape of the pointed end) can be adjusted as appropriate so that the hole formed has a desired shape.
  • the pointed member may be a member in which a plurality of pointed projections are arranged on a plane.
  • a latex rubber solution with a high solid content concentration is applied to the porous layer in which pores are formed.
  • Application methods include spray coating, dip coating, brush coating, roller coating, and the like.
  • the latex rubber solution with a high solids concentration permeates near the surface of the porous layer and near the inner wall surfaces of the pores.
  • the amount and method of application are adjusted so that the holes are not blocked and the latex rubber solution is not applied to the bottoms of the holes.
  • a nonwoven fabric coated with a latex rubber solution with a high solid content concentration is heated and dried to coagulate and harden the latex rubber. Due to this cohesive hardening, the area where latex rubber with a high solid content concentration is present becomes impermeable.
  • This includes a porous layer made of a non-breathable material and a porous layer, the porous layer having a base having a plurality of pores and a hollow portion extending into the porous layer from at least some of the pores. It is possible to obtain the sound absorbing material 10 shown in FIG. 1, which includes a neck portion having a shape.
  • the heat drying can be carried out at, for example, 60 to 100°C, and the appropriate equipment and conditions may be appropriately set according to the formulation of the latex rubber.
  • a heat press in addition to a heat press, an atmospheric furnace, a microwave heating device, etc. can be used.
  • a shape may be imparted to the nonwoven fabric by performing heat pressing using a mold or the like during heating and drying.
  • backing layer may be laminated together and integrally molded before hot pressing, or may be separately molded and laminated with the sound absorbing material.
  • a pointed member is used to form holes with the desired configuration in a plastic film, which is a non-breathable material.
  • a rubber tube made of non-breathable material and having the same inner diameter as this hole is bonded to the hole using an adhesive.
  • the adhesive include agents that form porous layers and adhesive layers between porous layers.
  • a pointed member is used to form pores with a desired arrangement and depth in the porous layer of nonwoven fabric.
  • the arrangement of the holes is made to match the arrangement of the rubber tube. Also, adjust the diameter of the hole to be the same as the outer diameter of the rubber tube.
  • the rubber tubes of the plastic film prepared as described above are laminated so as to fit into the holes of the nonwoven fabric, and the plastic film and the nonwoven fabric are bonded together using an adhesive.
  • the sound-absorbing material obtained in this way may be used in the form of a flat plate as a sound-absorbing sheet, or may be used in the form of a three-dimensional molded product.
  • This sound absorbing material in which the characteristic Helmholtz resonance box structure described above is formed, absorbs noise in a wide frequency range from low frequencies to high frequencies. Therefore, it can be suitably used as a sound-absorbing material in automobile parts, etc., and particularly suitably used as a fender liner or undercover that requires sound absorption of low-frequency road noise.
  • the wide frequency range referred to herein can be a frequency range of 500 to 6000 Hz, and the sound absorbing material has excellent sound absorption properties in the frequency range of 800 to 5000 Hz, particularly 1000 to 4000 Hz.
  • the vehicle member includes the above sound absorbing material.
  • the vehicle component may be an automobile component.
  • Exterior Vehicle parts and vehicle exterior materials that are sound absorbing materials for vehicle exterior materials. Exteriors include undercovers or under protectors (for vehicles), wheel house covers, soundproof covers, body panels, etc. Specifically, engine undercovers, floor undercovers, rear undercovers, transmission covers, fender liners/ Examples include protectors or mudguards, wheel house panels, door panels, floor panels, etc.
  • Interior Vehicle parts that are sound absorbing materials for vehicle interior materials, vehicle interior materials.
  • interior materials include vehicle silencers, vehicle soundproof bodies, etc., and specific examples include ceiling materials (roof silencers), dash silencers, floor silencers, floor carpets, hood silencers, and the like.
  • Others Sound absorbing materials for tires.
  • Examples of sound-absorbing materials for tires include sound-absorbing structures in which the above-mentioned sound-absorbing materials are combined with vehicle covers, cases, and the like.
  • a porous layer made of a non-breathable material and a porous layer made of a breathable material The porous layer includes a base having a plurality of pores and a hollow neck extending into the porous layer from at least some of the pores,
  • the Helmholtz resonant box structure includes a Helmholtz resonant box structure with a resonant frequency of less than 2000 Hz, a Helmholtz resonant box structure with a resonant frequency of 2000 to 3000 Hz, and a Helmholtz resonant box structure with a resonant frequency of greater than 3000 Hz.
  • ⁇ Materials used Examples 1 to 3> ⁇ PET film: ⁇ 29mm (for high frequency side measurement) or ⁇ 98mm (for low frequency side measurement), thickness 0.1mm ⁇ Silicone tube: length 7mm or 1mm, outer diameter 3mm, inner diameter 2mm ⁇ Glass nonwoven fabric: ⁇ 29mm (for high frequency side measurement) or ⁇ 98mm (for low frequency side measurement), thickness 12mm, ventilation resistance 2.0kPa ⁇ sec/m ⁇ Polypropylene/polyester mixed nonwoven fabric (product name Thinsulate (manufactured by 3M)): ⁇ 29mm (for high frequency side measurement) or ⁇ 98mm (for low frequency side measurement), thickness 13mm ⁇ Chloroprene rubber (CR) latex: Chauprene 671A (manufactured by Showa Denko K.K.) The air permeability resistance of the glass nonwoven fabric was measured by processing the glass nonwoven fabric into a size of ⁇ 40 mm using a punch and using an air permeability tester
  • Example 1 A circular hole with a diameter of 2 mm was punched in the PET film using a punch. Then, the inner diameter of the silicone rubber tube (length 7 mm) and the hole of the PET film were aligned with respect to some of the holes, and the silicone rubber tube was adhered. For adhesion, a plastic/synthetic rubber adhesive (trade name: Cemedine UT110 (urethane adhesive), manufactured by Cemedine Co., Ltd.) was used. As a result, a hole A portion (a hole having a neck portion) provided with a silicone rubber tube and a hole C portion (a hole having no neck portion) not including the silicone rubber tube were formed. The holes were arranged in a square lattice shape (see FIG.
  • Example 2 A circular hole with a diameter of 2 mm or 3 mm was punched in the PET film using a punch.
  • silicone rubber tubes with a length of 7 mm and a silicone rubber tube with a length of 1 mm were used together.
  • a hole A part and a hole B part holes having neck parts of lengths 7 mm and 1 mm, respectively, diameter 2 mm
  • a hole C part not provided with the silicone rubber tube a neck part A hole with a diameter of 3 mm
  • the holes were arranged in a regular triangular lattice shape (see FIG.
  • a metal/plastic adhesive was applied in the same manner as in Example 1 to the surfaces of the silicone rubber tube and PET film that were in contact with the glass nonwoven fabric. Holes with a diameter of 3 mm and a depth of 7 mm or 1 mm were punched in the glass nonwoven fabric at locations corresponding to the hole A section and hole B section, respectively, using a punch. Then, a silicone rubber tube of the PET film was inserted into the hole, and the PET film and the glass nonwoven fabric were laminated and bonded. In this way, a sound absorbing material (thickness: 12.1 mm) was produced.
  • Example 3 A glass nonwoven fabric was impregnated with the first CR latex solution having a solid content concentration of 20% by mass by spray coating. The amount of impregnation was 6000 g/m 2 . By heating this in an atmospheric furnace at 90° C., water was removed and the first CR latex was coagulated and hardened. The airflow resistance of the glass nonwoven fabric after the first CR latex was cured was 2.4 kPa ⁇ sec/m. A punch was used to form through holes with a diameter of 2 mm or 3 mm at desired locations in the glass nonwoven fabric in which the first CR latex was agglomerated and cured.
  • the holes were circular and arranged at a pitch of 8 mm in a regular triangular lattice pattern (see FIG. 6(b)).
  • a second CR latex solution having a solid content concentration of 50% by mass was applied by spray coating to the surface of the glass nonwoven fabric in which the through holes were formed and the surface of the holes.
  • the coating amount was 2000 g/m 2 .
  • holes with different neck lengths of 7 mm hole A part, ⁇ 2 mm), 1 mm (hole B part, ⁇ 2 mm), or 0 mm (hole C part, ⁇ 3 mm: no neck part is formed) are formed.
  • the coating method was adjusted so that holes of the same type were not adjacent to each other.
  • the porous layer was made of a composite material (non-breathable material) containing chloroprene rubber and glass nonwoven fabric, and the thickness of each of the base and neck was 1 mm.
  • the aperture ratio of the porous layer was 8%.
  • the porous layer consisted of a composite material (breathable material) containing non-woven glass and chloroprene rubber. In this way, a sound absorbing material (thickness: 12 mm) was produced.
  • Example 2 In the same manner as in Example 3, a glass nonwoven fabric was produced by coagulating and curing the first CR latex. This was used as a sound absorbing material (thickness: 12 mm).
  • Example 4 In a polycup, the solid content ratio was 100 parts by mass of Chauprene 671A (manufactured by Showa Denko Co., Ltd., chloroprene rubber latex), 7.5 parts by mass of zinc oxide AZ-SW (manufactured by Osaki Kogyo Co., Ltd., accelerator), and Adekanol UH- 752 (manufactured by ADEKA Corporation, thickener) was added, and the mixture was stirred and mixed for 15 minutes at 700 rpm using a magnetic stirrer RS-1DN (manufactured by As One As One). This was used as latex for skin layer (porous layer).
  • a magnetic stirrer RS-1DN manufactured by As One As One
  • a foam stabilizer and a gelling agent were added to a polycup, and mixed using a magnetic stirrer at 700 rpm for 10 minutes. This was added to the latex for the skin layer, and stirred and mixed for 3 minutes at 700 rpm using a magnetic stirrer. This was used as a skin layer (porous layer) forming liquid.
  • a foam stabilizer and a gelling agent were added to a polycup, and mixed using a magnetic stirrer at 700 rpm for 10 minutes. This was added to the latex for the porous layer, and stirred and mixed for 1 minute at 700 rpm using a magnetic stirrer. The mixed solution was further stirred for 2 minutes at high rotational speed using a swing cook hand mixer MEK-66 (manufactured by Estale, attachments: whipper, switch II (ultra high speed)) to raise the foaming ratio to 7 times. Made it foam. This was used as a porous layer forming liquid.
  • An upper mold having a flat plate portion having a plurality of holes and a hollow extending portion extending from at least some of the holes was immersed in a skin layer forming liquid to adhere the skin layer forming liquid to the surface of the upper mold. .
  • As the upper mold one having a hole and an extension part such that the three types of neck parts shown in Table 3 and FIG. 6(b) were formed was used. Air was flowed into the hollow extension part from the hole in the upper part of the upper mold, and the skin layer forming liquid covering the tip of the extension part was removed. Then, the holes in the upper mold were covered with masking tape.
  • the porous layer forming liquid was poured into the lower mold, and the upper mold to which the skin layer forming liquid was attached was placed on top of the mold and the mold was clamped. This state was left at room temperature (25° C.) for 10 minutes to gel each solution.
  • the gelled product of each solution was taken out from the mold and heated in a constant temperature bath at 120°C for 4 hours.
  • the sample after heating was taken out from the constant temperature bath and washed with water.
  • a sound absorbing material was produced as described above.
  • the produced sound absorbing material includes a porous layer containing a rubber foam, a porous layer provided on the porous layer and containing rubber having a lower open porosity than the porous layer, and the porous layer has a plurality of pores. and a hollow neck extending into the porous layer from at least some of the pores.
  • Example 4 When the sound absorbing material of Example 4 was analyzed using a three-dimensional measurement X-ray CT device (inspeXio SMX-225CT, manufactured by Shimadzu Corporation), the open porosity of the porous layer was 1.2%, and the open porosity of the porous layer was 1.2%. : 84.2%, base thickness: 0.36 mm, neck thickness: 0.46 mm, and neck length: 7.02 mm. Further, the thickness of the sound absorbing material was 12 mm. The aperture ratio of the base was 7.68%.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Mechanical Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)

Abstract

L'invention concerne un matériau absorbant acoustique pourvu d'une couche à trous multiples comprenant un matériau non perméable à l'air, et une couche poreuse comprenant un matériau perméable à l'air, la couche à trous multiples étant pourvue d'une partie de base dotée d'une pluralité de trous, et de parties de col creuses s'étendant à partir d'au moins certains des trous de la couche poreuse, et lorsque le matériau absorbant acoustique est disposé avec le côté de couche poreuse faisant face à un élément d'objet, deux types ou plus de structures de boîtier de résonance de Helmholtz ayant différentes fréquences de résonance, qui sont résonantes avec des sons incidents à partir des trous, sont formés.
PCT/JP2023/011290 2022-03-28 2023-03-22 Matériau absorbant acoustique et élément de véhicule WO2023189959A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011180381A (ja) * 2010-03-01 2011-09-15 Nagoya Oil Chem Co Ltd 吸遮音パネル部材
JP2012123293A (ja) * 2010-12-10 2012-06-28 Toshiba Corp 静止誘導電器および低周波吸音壁
JP2012255967A (ja) * 2011-06-10 2012-12-27 Aisin Chemical Co Ltd 熱硬化防音塗料組成物
JP2018101001A (ja) * 2016-12-19 2018-06-28 三菱重工業株式会社 消音装置、回転機械、消音装置の製造方法
JP2018141839A (ja) * 2017-02-27 2018-09-13 日東電工株式会社 吸音材
JP2020122917A (ja) * 2019-01-31 2020-08-13 イビデン株式会社 吸音材

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011180381A (ja) * 2010-03-01 2011-09-15 Nagoya Oil Chem Co Ltd 吸遮音パネル部材
JP2012123293A (ja) * 2010-12-10 2012-06-28 Toshiba Corp 静止誘導電器および低周波吸音壁
JP2012255967A (ja) * 2011-06-10 2012-12-27 Aisin Chemical Co Ltd 熱硬化防音塗料組成物
JP2018101001A (ja) * 2016-12-19 2018-06-28 三菱重工業株式会社 消音装置、回転機械、消音装置の製造方法
JP2018141839A (ja) * 2017-02-27 2018-09-13 日東電工株式会社 吸音材
JP2020122917A (ja) * 2019-01-31 2020-08-13 イビデン株式会社 吸音材

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