JP2018146942A - Laminated sound absorption material including ultrafine fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorption material exhibiting excellent sound absorbing performance in a low frequency region and also having an excellent space-saving property.SOLUTION: A laminated sound absorption material comprises a plurality of fiber layers and a base material layer interposed between the fiber layers. The laminated sound absorption material includes at least three fiber layers. Each of the fiber layers is made of fibers having a fiber diameter of more than or equal to 500 nm and less than 35 μm and a basis weight of 10 to 500 g/m. The base material layer has a basis weight of more than or equal to 10 g/mand a thickness of more than or equal to 0.1 mm. The base material layer is at least one selected from the group consisting of nonwoven fabric and woven fabric.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sound-absorbing material having a laminated structure that includes ultrafine fibers.

  The sound absorbing material is a product having a function of absorbing sound, and is often used in the construction field and the automobile field. It is known to use a nonwoven fabric as a material constituting the sound absorbing material. For example, Patent Document 1 discloses a composite nonwoven web including submicron fibers having a median diameter of less than 1 μm and microfibers having a median diameter of at least 1 μm. The composite fiber web of Patent Document 1 is a mixture of fibers having two different median diameters called sub-micron fibers and microfibers, and the mixing ratio is changed in the thickness direction by changing the mixing ratio. To form a heterogeneous fiber mixture. In an exemplary embodiment, it is disclosed that a microfiber stream can be formed and a sub-micron fiber stream can be separately formed and added to the microfiber stream to form a web of different fibers mixed together. .

Further, Patent Document 2 includes a support layer and a submicron fiber layer laminated on the support layer as a multilayer article having sound absorption properties. The submicron fiber layer has a center fiber diameter of less than 1 μm and an average value. It is disclosed that the fiber diameter is in the range of 0.5 to 0.7 μm and formed by a melt film fibrillation method or an electrospinning method. In Examples of Patent Document 2, a polypropylene spunbonded nonwoven fabric having a basis weight (weight per unit area) of 100 g / m ² and a diameter of about 18 μm is used as a support layer, and a basis weight of 14 to 50 g / m ² and an average fiber diameter of about 0 are used. Laminated articles laminated with .56 μm submicron polypropylene fibers are disclosed. In another embodiment, the basis weight 62 g / ^m on a polyester card processing web ^2, basis weight 6~32g / ^{m 2,} the multilayer article is disclosed as a laminate of electrospun polycaprolactone fibers having an average fiber diameter of 0.60μm Has been. The multilayer articles made in the examples are measured for acoustic absorption properties and have been shown to have better acoustic absorption properties than those of the support alone.

Patent Document 3 discloses a laminated sound-absorbing nonwoven fabric that absorbs low-frequency and high-frequency sounds, and includes a resonance film and at least one other fiber material layer. The resonance film has a surface weight (weight per unit area) up to a diameter of 600 nm. ) What is formed by 0.1-5 g / m < ² > nanofiber layer is disclosed. The nanofiber layer is typically created by electrospinning, while the substrate layer is a fiber fabric having a diameter of 10 to 45 μm and a basis weight of 5 to 100 g / m ² , and further layers may be laminated. Is disclosed. Further, it is disclosed that this laminate may be further laminated in order to reach an appropriate thickness and basis weight.

Patent Document 4 discloses a non-woven fabric structure that is excellent in sound absorption characteristics using nanofibers. The nonwoven fabric structure of Patent Document 4 includes a fibrous body containing nanofibers having a fiber diameter of less than 1 μm, and the thickness of the fibrous body is 10 mm or more. Further, it is disclosed that the fibrous body may be supported by a support, or may have a structure in which the fibrous body and the support are repeatedly laminated. The nanofibers are formed by, for example, a melt-blowing method. In an embodiment, a nanofiber body layer having a fiber diameter of 0.5 μm and a basis weight of 350 g / m ² is formed on a polypropylene spunlace nonwoven fabric as a support. Has been.

Special table 2011-508113 gazette JP 2014-15042 A Special table 2008-537798 gazette JP 2016-112426 A

  As described above, non-woven fabric laminates having various configurations have been studied as sound absorbing materials, and it is also known to use ultrafine fibers called nanofibers or submicron fibers whose fiber diameter is less than 1 μm. However, there is a demand for a sound-absorbing material having more excellent sound-absorbing characteristics, particularly a sound-absorbing material that exhibits excellent sound-absorbing performance in a relatively low frequency region of 1000 Hz or less and is excellent in space saving. In view of this situation, an object of the present invention is to provide a sound-absorbing material that exhibits excellent sound-absorbing properties in a low-frequency region.

  The inventor has repeatedly studied to solve the above-described problems. As a result, the laminated sound-absorbing material including the base material layer and the fiber layer includes at least three fiber layers having a specific range of fiber diameter and basis weight, and has a specific range of basis weight and thickness between the fiber layers. The laminated sound-absorbing material including the base material layer was found to exhibit excellent sound-absorbing properties in the low-frequency region and excellent in space-saving properties, thus completing the present invention.

［６］垂直入射吸音率測定法（２００〜１０００Ｈｚ）において、周波数ｘが２００Ｈｚから３２００Ｈｚまでの吸音率を１Ｈｚ間隔で測定し、得られる曲線をｆ（ｘ）としたとき、２００Ｈｚから１０００Ｈｚまでの積分した値Ｓが、下記式を満たす範囲である、
［１］〜［４］のいずれか１項に記載の積層吸音材。

The present invention has the following configuration.
[1] A laminated sound-absorbing material comprising a plurality of fiber layers and a base material layer interposed between the fiber layers,
The laminated sound absorbing material includes at least three fiber layers,
Each fiber layer is composed of fibers having a fiber diameter of 500 nm or more and less than 35 μm, and has a basis weight of 10 to 500 g / m ² .
The base material layer has a basis weight of 10 g / m ² or more, a thickness of 0.1 mm or more,
The said base material layer is a laminated sound-absorbing material which is at least 1 chosen from the group which consists of a nonwoven fabric and a woven fabric.
[2] The laminated sound-absorbing material according to [1], wherein the fiber layer has a basis weight of 10 to ²⁰⁰ g / m ² .
[3] The fibers forming the fiber layer are made of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polytetrafluoroethylene, polyvinylidene fluoride, nylon 6.6, polyacrylonitrile, polystyrene, polyurethane, polysulfone and polyvinyl alcohol. The laminated sound-absorbing material according to [1] or [2], which is at least one selected from the group consisting of:
[4] The base material contained in the base material layer is a non-woven fabric made of at least one selected from the group consisting of polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene fiber and polypropylene fiber, and the basis weight of the base material is 10 a ^{~500g / m 2, [1]} ~ stacked sound-absorbing material according to any one of [3].
[5] In the normal incident sound absorption coefficient measurement method (200 to 1000 Hz), the sound absorption coefficient from 200 Hz to 3200 Hz is measured at intervals of 1 Hz, and the obtained curve is f (x), from 200 Hz to 1000 Hz. The laminated sound-absorbing material according to any one of [1] to [4], wherein the integrated value S is a range satisfying the following formula.

[6] In the normal incidence sound absorption coefficient measurement method (200 to 1000 Hz), the sound absorption coefficient at a frequency x from 200 Hz to 3200 Hz is measured at intervals of 1 Hz, and the obtained curve is f (x), from 200 Hz to 1000 Hz. The integrated value S is in a range that satisfies the following formula:
The laminated sound-absorbing material according to any one of [1] to [4].

  According to the present invention having the above-described configuration, a laminated sound absorbing material having excellent sound absorbing characteristics in a low frequency region can be obtained. The laminated sound-absorbing material of the present invention is in a region where the peak of sound-absorbing characteristics is lower than that of conventional sound-absorbing materials, and is excellent in sound-absorbing performance in a region of 1000 Hz or less. In the construction field, most of the daily noise is said to be about 200 to 500 Hz. In the automobile field, road noise is about 100 to 500 Hz, and noise during acceleration and transmission fluctuation is said to be about 100 to 2000 Hz. . The laminated sound-absorbing material of the present invention is useful for such noise countermeasures. In addition, since the laminated sound absorbing material of the present invention is lighter than the sound absorbing material made of porous material, glass fiber, etc., it is possible to reduce the weight of the member and save space. It is useful as a sound absorbing material.

It is a graph which shows the sound absorption characteristic of the Example (Example 1) of this invention, and a comparative example (comparative example 1).

  Hereinafter, the present invention will be described in detail.

(Structure of laminated sound absorbing material)
The laminated sound absorbing material of the present invention is a laminated sound absorbing material including a plurality of fiber layers and a base material layer interposed between the fiber layers, and the laminated sound absorbing material includes at least three fiber layers. each fiber layer comprises fibers having a fiber diameter of less than 500 nm 35 [mu] m, and a basis weight of 10 to 500 g / ^{m 2,} the base layer is 10 g / ^{m 2} or more basis weight, thickness 0 The base material layer is at least one selected from the group consisting of a nonwoven fabric and a woven fabric. Thus, the laminated sound-absorbing material of the present invention includes the base material layer and the fiber layer. Three or more fiber layers are included in the laminated sound-absorbing material, and a base material layer is interposed between the fiber layers.

In the laminated sound-absorbing material, the fiber layer includes three or more layers, preferably 3 to 6 layers, more preferably 3 to 4 layers. Each fiber layer may be one fiber assembly or may be a form in which a plurality of fiber assemblies are stacked in one fiber layer.
In the laminated sound-absorbing material, a base material layer is interposed between the fiber layers. Each base material layer may consist of one base material, or may have a form in which a plurality of base materials are stacked.

  The fiber layer and the base material layer included in the laminated sound-absorbing material may each be one kind, but two or more different fiber layers or base material layers may be included. Moreover, unless the effect of this invention is impaired, structures other than a fiber layer and a base material layer may be contained, for example, the additional fiber layer (1 layer or 2 layers or more outside the range prescribed | regulated to this invention may be sufficient. ), Printed layers, foams, foils, meshes, woven fabrics, and the like. Further, an adhesive layer, a clip, a suture thread and the like for connecting the respective layers may be included.

  The layers of the laminated sound absorbing material may be physically and / or chemically bonded, or may not be bonded. The laminated sound-absorbing material may have a form in which a part of the plurality of layers is bonded and a part of the laminated sound-absorbing material is not bonded. Adhesion is performed, for example, by heating in the fiber layer forming step or as a subsequent step, melting a part of the fibers constituting the fiber layer, and fusing the fiber layer to the substrate. May be adhered. Moreover, it is also preferable to adhere | attach an interlayer by providing an adhesive agent on the surface of a base material or a fiber layer, and also overlaying a base material layer or a fiber layer.

  The thickness of the laminated sound-absorbing material is not particularly limited as long as the effects of the present invention can be obtained. For example, it can be 0.1 to 50 mm, preferably 0.3 to 40 mm, from the viewpoint of space saving. More preferably, the thickness is 0.3 to 30 mm. The thickness of the laminated sound-absorbing material typically means the total thickness of the fiber layer and the base material layer. When an exterior body such as a cartridge or a lid is attached, the thickness of that portion is included. Make it not exist.

  The air permeability of the laminated sound absorbing material is not particularly limited as long as the desired sound absorbing performance can be obtained, but can be 10 to 1000 μm / Pa · s, and more preferably 10 to 500 μm / Pa · s. . Conventionally, in a sound absorbing material that was expected to have a sound absorbing performance as well as a sound absorbing performance, it was thought that the lower the air permeability, the harder the sound passes, that is, it is considered effective for the sound insulating property, but the laminated sound absorbing material of the present invention is high. By having a breathability, sound reflection is reduced, and by adopting a fiber layer excellent in sound absorption, high sound absorption is obtained. The air permeability can be measured by a known method, for example, the Gurley tester method.

  The laminated sound-absorbing material has a laminated structure in which a fiber layer is sandwiched between base layers. In such a form, the distance between the fiber layer (also referred to as the thickness of the base material layer and the interlayer distance) is preferably 100 μm to 15 mm, and more preferably 100 μm to 10 mm. . If the interlayer distance is 100 μm or more, the sound absorption performance in the low frequency region is good, and if the interlayer distance is 15 mm or less, the thickness of the sound absorbing material does not become too large, which is suitable for space saving.

(Fiber layer)
The fiber layer contained in the laminated sound-absorbing material of the present invention is a layer made of fibers having a fiber diameter of 500 nm or more and less than 35 μm. Preferably, it is a layer made of fibers having a fiber diameter of 500 nm or more and less than 30 μm. That the fiber diameter is 500 nm or more and less than 35 μm means that the average fiber diameter is within this numerical range. A fiber diameter in the range of 500 nm to 35 μm is preferable because high sound absorption is obtained. The fiber diameter can be measured by a known method. For example, it is a value obtained by measurement or calculation from an enlarged photograph of the fiber layer surface, and a detailed measurement method will be described in detail in Examples.

The fiber layer included in the laminated sound-absorbing material of the present invention may have one fiber layer made of one fiber assembly, and a plurality of fiber assemblies in one fiber layer, The layer of body layers may form a single fiber layer. In addition, in this specification, a fiber assembly means the fiber assembly used as one continuous body formed on one layer of a base material. The basis weight of the fiber assembly is preferably 10 to 500 g / m ² . If the basis weight is 10 g / m ² or more, the control of the flow resistance due to the density difference between the fine fiber layer and the base fiber is good, and if it is less than 500 g / m ² , the sound absorbing material is excellent in productivity.

  The fiber aggregate constituting the fiber layer is preferably a non-woven fabric, and is not particularly limited as long as it has a fiber diameter and basis weight in the above-mentioned range. Is preferred. According to the melt blown nonwoven fabric, the ultrafine fibers can be efficiently laminated on the substrate. Details of the melt blown nonwoven fabric will be described in detail in the production method.

  The resin constituting the fiber assembly is not particularly limited as long as the effects of the invention can be obtained. For example, polyolefin resins, polyurethane, polylactic acid, acrylic resins, polyesters such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, Nylon 6.6, nylon 12 such as nylon (amide resin), polyphenylene sulfide, polyvinyl alcohol, polystyrene, polysulfone, liquid crystal polymer, polyethylene-vinyl acetate copolymer, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride Examples include hexafluoropropylene. Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of the polyethylene resin include low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE). Examples of the polypropylene resin include propylene homopolymers, propylene and others. And a copolymerized polypropylene obtained by polymerizing ethylene, butene and the like. The fiber assembly preferably contains one kind of the above-mentioned resins, and may contain two or more kinds.

  The laminated sound-absorbing material of the present invention can be produced using a known method, and the production method is not particularly limited. For example, the laminated sound-absorbing material can be produced by laminating a base material layer and an adhesive layer nonwoven fabric in this order and thermally bonding them. Specifically, an elastomer resin or a hot melt resin to be an adhesive layer is extruded in a molten state from a nozzle, sprayed onto a base material layer with heated and compressed air, and laminated in a sheet shape to form an adhesive layer of a melt blown nonwoven fabric. . Subsequently, a fiber layer of a melt blown nonwoven fabric can be formed on the adhesive layer by extruding a resin to be a fiber layer in a molten state from the nozzle and spraying it with heated compressed air. The basis weight can be arbitrarily set by adjusting the speed of the conveyor that conveys the base material layer.

  This laminated sound-absorbing material is, for example, passed through a calendering machine having a flat (smooth) roll and a flat (smooth) roll to melt the adhesive layer to bond each layer, and simultaneously perform the surface treatment of the fiber layer. A laminated sound-absorbing material can be obtained. The conditions for the calendar treatment can be, for example, a speed of 10 to 200 m / min, a roll temperature of 60/60 to 160/160 ° C., and a pressure of 20 to 100 N / mm, but may be adjusted according to the purpose and is not particularly limited. .

  The fiber assembly may contain various additives other than the resin. Examples of additives that can be added to the resin include fillers, stabilizers, plasticizers, adhesives, adhesion promoters (eg, silanes and titanates), silica, glass, clay, talc. Pigments, colorants, antioxidants, fluorescent brighteners, antibacterial agents, surfactants, flame retardants, and fluorinated polymers. One or more of the above additives may be used to reduce the weight and / or cost of the resulting fiber and layer, to adjust the viscosity, or to modify the thermal properties of the fiber. Alternatively, various physical property activities derived from the properties of the additive may be imparted, including electrical properties, optical properties, density properties, liquid barrier or tack properties.

(Base material layer)
The base material layer in the laminated sound absorbing material has a sound absorbing property and also has a function of supporting the fiber layer and maintaining the shape of the entire sound absorbing material. The base material layer may consist of a single base material, or may have a form in which a plurality of base materials are stacked.
The base material constituting the base material layer is not particularly limited as long as the fiber aggregate can be laminated on at least one surface thereof, and at least one selected from the group consisting of a nonwoven fabric and a woven fabric can be used. . In particular, the base material layer is more preferably a nonwoven fabric. One type of substrate may be included in the laminated sound-absorbing material, and it is also preferable that two or more types of substrates are included. Since these are particularly preferable to have air permeability, when the air permeability is low, it is preferable to have an opening.

  When the substrate is a nonwoven fabric, the type of nonwoven fabric can be selected from melt blown nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, through-air nonwoven fabric, thermal bond nonwoven fabric, needle punched nonwoven fabric, and the like depending on the desired physical properties and functions. .

As the resin constituting the fibers of the nonwoven fabric, a thermoplastic resin can be used. Examples thereof include polyolefin resins, polyester resins such as polyethylene terephthalate, and polyamide resins. Examples of polyolefin resins include homopolymers such as ethylene, propylene, butene-1, or 4-methylpentene-1, and these and other α-olefins, that is, ethylene, propylene, butene-1, pentene-1, A random or block copolymer with one or more of hexene-1 or 4-methylpentene-1, or a combination of these, or a mixture thereof. Polyamide resins include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 6.6, nylon 6.10, polymetaxylidene adipamide, polyparaxylidenedecanamide, polybiscyclohexylmethanedecane. Amides or their copolyamides can be mentioned. Examples of the polyester resin include polyethylene terephthalate, polytetramethylene terephthalate, polybutyl terephthalate, polyethylene oxybenzoate, poly (1,4-dimethylcyclohexane terephthalate), and copolymers thereof. Among these, it is preferable to use one or a combination of two or more of polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene fiber, and polypropylene fiber.
The same resin can be used when the substrate is a woven fabric.

  As the fiber constituting the nonwoven fabric of the base material, it can be used with only one component, but considering the fusion effect at the intersection of the heat-adhesive fibers, from the composite component of the low melting point resin and the high melting point resin It is also preferable to use a composite fiber composed of two or more components having different melting points. Examples of the composite form include a sheath core type, an eccentric sheath core type, and a parallel type. Moreover, it is also preferable to use a mixed fiber of two or more components having different melting points as the fiber constituting the nonwoven fabric of the base material. The mixed fiber means a fiber in which fibers made of a high melting point resin and fibers made of a low melting point resin exist independently and are mixed. Similar fibers can also be used when the substrate is a woven fabric.

  Although the fiber diameter of the fiber which comprises the nonwoven fabric of a base material is not restrict | limited in particular, what consists of a fiber whose fiber diameter is 1 micrometer-1 mm can be used. The fiber diameter of 1 μm to 1 mm means that the average fiber diameter is within this numerical range. If the fiber diameter is 1 μm or more, the flow resistance due to the density difference between the fiber layer and the base fiber can be controlled, and if it is less than 1 mm, versatility is not lost and it is easy to obtain. . A fiber diameter of 1.0 to 100 μm is more preferable because the flow resistance due to the density difference between the fiber layer and the base fiber can be controlled and is easily available. The measurement of the fiber diameter can be performed by the same method as the measurement of the fiber diameter of the fiber layer. The flow resistance referred to here is an index representing the difficulty of the air flowing through the sound absorbing material. Even when the substrate is a woven fabric, fibers having the same fiber diameter can be used.

  The base material is interposed between the fiber layers. In addition to being interposed between the fiber layers, the laminated sound-absorbing material may be included as two layers located on the outermost surface. A base material may comprise a base material layer only by 1 layer, and it is also preferable that 2 or more layers are arrange | positioned continuously and comprise the 1-layer base material layer. By arranging two or more base materials continuously, there is an advantage that the interlayer distance of the fiber layer can be controlled by the thickness of the base material layer.

Basis weight of the substrate may be any 10 g / ^{m 2} or more, preferably 10 to 300 g / ^{m 2,} and more preferably 15~300g / ^{m 2.} If the basis weight of the substrate is 10 g / m ² or more, the strength required as a sound absorbing material can be obtained.

  In the present invention, the base material layer has a thickness of 0.1 mm or more. Although the upper limit of the thickness of the base material layer is not particularly limited, it is preferably 0.1 to 60 mm, more preferably 0.1 to 30 mm from the viewpoint of space saving. The thickness of the base material which comprises a base material layer can be 20 micrometers-20 mm, for example, and it is more preferable to set it as 30 micrometers-10 mm. If the thickness of the base material is 20 μm or more, wrinkles are not generated and handling is easy and productivity is good. If the thickness of the base material is 20 mm or less, there is no risk of hindering space saving.

  For the base material, various additives such as a colorant, an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizing agent, a nucleating agent, a lubricant, and an antibacterial agent are provided as long as the effects of the present invention are not impaired. In addition, flame retardants, plasticizers and other thermoplastic resins may be added. Moreover, the surface may be processed with various finishing agents, and functions, such as water repellency, antistatic property, surface smoothness, and abrasion resistance, may be provided by this.

(Sound absorption characteristics of laminated sound absorbing material)
The laminated sound-absorbing material of the present invention is particularly characterized by excellent sound-absorbing properties in a low frequency region (frequency region of 1000 Hz or less). The laminated sound-absorbing material of the present invention exhibits sound-absorbing characteristics different from those of conventional sound-absorbing materials, in particular, excellent in sound-absorbing properties in the 400 Hz to 1000 Hz region. Although not bound by a specific theory, the laminated sound-absorbing material of the present invention is superior in absorbency in the low-frequency region as a result of controlling the flow resistance of sound waves using the density difference between the fiber layer and the base material layer. It is believed that performance can be obtained.
The sound absorption evaluation method is described in detail in Examples.

(Production method of laminated sound-absorbing material)
The production method of the laminated sound-absorbing material is not particularly limited, but for example, a step of forming a fiber layer that forms a single fiber assembly on a single base material, and a plurality of fiber layers in a predetermined order and number It can obtain by the manufacturing method including the process of superimposing and integrating. In the step of overlapping the fiber layers, additional layers other than the fiber layers (for example, further base materials) can be further added and laminated.

  When using a nonwoven fabric as a base material, a nonwoven fabric may be manufactured and used by a well-known method, and a commercially available nonwoven fabric can also be selected and used. The step of forming the fiber layer on the substrate preferably uses a melt blow method or an electrospinning method. Moreover, when using a woven fabric as a base material, a woven fabric may be manufactured and used by a well-known method, and a commercially available woven fabric can also be selected and used.

  The melt blow method is a method of forming a nonwoven fabric by extruding a resin that becomes a fiber layer on a base material layer from a nozzle in a molten state and spraying it with heated compressed air. For example, two extruders having a screw, a heating element and a gear pump, a spinneret for blending fibers, a compressed air generator and an air heater, a collecting conveyor equipped with a polyester net, and a nonwoven fabric manufacturing apparatus comprising a winder Can be used to produce a nonwoven fabric. The basis weight can be arbitrarily set by adjusting the speed of the conveyor that conveys the base material layer. The resin used for spinning is not particularly limited as long as it has thermoplasticity and has spinnability.

  The electrospinning method is a method in which a spinning solution is discharged and an electric field is applied to fiberize the discharged spinning solution to obtain fibers on a collector. For example, a method of spinning by spinning the spinning solution from the nozzle and applying an electric field, a method of spinning by spinning the spinning solution and applying an electric field, and spinning by directing the spinning solution to the surface of a cylindrical electrode and applying an electric field. And the like. In this invention, the nonwoven fabric etc. which become a base material can be inserted on a collector, and a fiber can be integrated | stacked on a base material. The spinning solution is not particularly limited as long as it has spinnability, but a solution in which a resin is dispersed in a solvent, a solution in which a resin is dissolved in a solvent, a solution in which a resin is melted by heat or laser irradiation, and the like. Can be used.

  For the purpose of improving the spinning stability and fiber forming property, a surfactant may be further added to the spinning solution. Examples of the surfactant include an anionic surfactant such as sodium dodecyl sulfate, a cationic surfactant such as tetrabutylammonium bromide, and a nonionic surfactant such as polyoxyethylene sorbitamon monolaurate. Can be mentioned. The concentration of the surfactant is preferably in the range of 5% by weight or less with respect to the spinning solution. If it is 5 weight% or less, since the improvement of an effect commensurate with use is obtained, it is preferable. In addition, components other than those described above may be included as components of the spinning solution as long as the effects of the present invention are not significantly impaired.

  The method of stacking and integrating a plurality of laminates of fibers comprising two layers of the base material / fiber structure obtained as described above is not particularly limited. It is also possible to employ various bonding methods, that is, thermocompression bonding using a heated flat roll or embossing roll, bonding using a hot melt agent or a chemical adhesive, thermal bonding using circulating hot air or radiant heat, and the like. From the viewpoint of suppressing deterioration of physical properties of the fiber layer containing ultrafine fibers, heat treatment with circulating hot air or radiant heat is particularly preferable. In the case of thermocompression bonding using a flat roll or embossing roll, the fiber layer may be melted to form a film, or damage may occur such as tearing around the embossing point, which may make stable production difficult. In addition, it tends to cause performance degradation such as deterioration of sound absorption characteristics. Moreover, in the case of adhesion | attachment by a hot-melt agent or a chemical adhesive agent, the inter-fiber space | gap of a fiber layer is filled with this component, and it may be easy to produce a performance fall. On the other hand, it is preferable to integrate by heat treatment with circulating hot air or radiant heat because the fiber layer is less damaged and can be integrated with sufficient delamination strength. In the case of integration by heat treatment with circulating hot air or radiant heat, although not particularly limited, it is preferable to use a nonwoven fabric and a laminate made of heat-fusible conjugate fibers.

  The following examples are for illustrative purposes only. The scope of the present invention is not limited to this example.

積分値Ｓは２００〜１０００Ｈｚの周波数領域の吸音性能を示し、数値が高ければ、吸音性が高いと判断される。Ｓ値が１７０を超える場合、低周波数領域の吸音性を良好と評価し、１７０未満の場合、吸音性を不良と評価した。
＜通気度＞
通気度測定は、株式会社東洋精機製作所製ガーレ式デンソメーター（型式：ＧＢ−３Ｃ）にてＩＳＯ ５６３６に準拠し測定した。
＜ＭＦＲ＞
ポリプロピレン樹脂のＭＦＲは、ＪＩＳ Ｋ ７２１０（１９９９）に準拠し、２１６０ｇ荷重条件下、２３０℃で測定した値である。
ポリエチレン樹脂のＭＦＲは、ＪＩＳ Ｋ ７２１０（１９９９）に準拠し、２１６０ｇ荷重条件下、１９０℃で測定した値である。 The measurement methods and definitions of the physical property values shown in the examples are shown below.
<Average fiber diameter>
A scanning electron microscope SU8020 manufactured by Hitachi High-Technologies Corporation was used to observe the ultrafine fibers, and the diameter of 50 ultrafine fibers was measured using image analysis software. The average value of the fiber diameters of 50 ultrafine fibers was defined as the average fiber diameter.
<Measurement of sound absorption coefficient>
The sound absorption coefficient is obtained by collecting a sample having a diameter of 63 mm from each fiber laminate, laminating the respective conditions, and using a normal incident sound absorption coefficient measuring device “TYPE 4206 manufactured by Brüel & Care Co.” in accordance with ASTM E 1050. The normal incidence sound absorption coefficient when a plane sound wave was perpendicularly incident on a test piece at 200 to 3200 Hz was measured.
<Sound absorption in low frequency range>
When the sound absorption rate from the frequency x of 200 Hz to 3200 Hz is measured at intervals of 1 Hz, and the obtained curve is f (x), an integral value S from 200 Hz to 1000 Hz is obtained by the following equation.

The integrated value S indicates the sound absorption performance in the frequency range of 200 to 1000 Hz. If the numerical value is high, it is determined that the sound absorption is high. When the S value exceeded 170, the sound absorption in the low frequency region was evaluated as good, and when it was less than 170, the sound absorption was evaluated as poor.
<Air permeability>
The air permeability was measured according to ISO 5636 using a Gurley type densometer (model: GB-3C) manufactured by Toyo Seiki Seisakusho.
<MFR>
The MFR of the polypropylene resin is a value measured at 230 ° C. under a load of 2160 g in accordance with JIS K 7210 (1999).
The MFR of the polyethylene resin is a value measured at 190 ° C. under a load of 2160 g in accordance with JIS K 7210 (1999).

[Example 1]
A high-density polyethylene “M6900” (MFR 17 g / 10 min) made by KEIYO polyethylene is used as the high-density polyethylene resin, and a polypropylene homopolymer “SA3A” (MFR = 11 g / 10 min) made by Nippon Polypro is used as the polypropylene resin. Then, a sheath-core type heat-fusible conjugate fiber having a sheath component with a fiber diameter of 22 μm and a core component composed of a high-density polyethylene resin and a core component composed of a polypropylene resin was produced by a hot melt spinning method. Using the obtained sheath-core type heat-fusible conjugate fiber, a card method through-air nonwoven fabric having a basis weight of 200 g / m ² , a thickness of 5 mm, and a width of 1000 mm was prepared and used as a base material.
For the formation of the fiber layer, two extruders having a screw (50 mm diameter), a heating element and a gear pump, a spinneret for blending fibers (hole diameter 0.3 mm, holes through which resin is alternately discharged from two extruders) A non-woven fabric manufacturing apparatus including an effective width of 500 mm in which several 501 holes are arranged in a line, a compressed air generator and an air heater, a collection conveyor provided with a polyester net, and a winder was used.
As a raw material polypropylene resin, polypropylene homopolymer 1 (MFR = 82 g / 10 min) and polypropylene homopolymer 2 (“FR-185” (MFR = 1400 g / 10 min) manufactured by LOTTE CHEMICAL) are used. The two types of polypropylene resins are put into two extruders, the extruder is heated and melted at 240 ° C., and the mass ratio of the gear pump is set to 50/50, and 0.3 g per single hole from the spinneret. The molten resin was discharged at a spinning speed of / min. The discharged fiber is sprayed onto the laminated body on which the fiber layer and the base material layer are laminated on the collection conveyor at a distance of 30 cm from the spinneret by compressed air of 98 kPa (gauge pressure) heated to 400 ° C. Formed. The basis weight was arbitrarily set by adjusting the speed of the collecting conveyor. The average fiber diameters were 0.7 μm and 2 μm, respectively, and the basis weight of the fiber layer was 80 g / m ² .
Using the obtained fiber layer and base material, the layers were laminated so as to be fiber layer / base material layer / base material layer / fiber layer / base material layer / base material layer / fiber layer, cut into a 63 mm diameter circle, and measured for sound absorption coefficient. A sample was created. When the normal incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (integrated value S from 200 Hz to 1000 Hz) was evaluated, it was 447.2, which was favorable.

[Example 2]
A PTFE (polytetrafluoroethylene) thickness 1 mm and a basis weight of 500 g / m ² (model number PF100) manufactured by ADVANTEC, which are commercially available as a fiber layer, were prepared.
Further, as a base material layer, a card method through-air nonwoven fabric having a basis weight of 200 g / m ² , a thickness of 5 mm, and a width of 1000 mm (here, the sheath-core type heat-fusible conjugate fiber manufactured in Example 1 was used). Prepared and prepared.
Using a fiber layer and a base material, the fiber layer / base material layer / base material layer / fiber layer / base material layer / base material layer / fiber layer are laminated and cut into a 63 mm diameter circle for measuring sound absorption coefficient. A sample was created. When the normal incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (integrated value S from 200 Hz to 1000 Hz) was evaluated, it was 424.6, which was good.

[Example 3]
A PTFE (polytetrafluoroethylene) thickness 0.95 mm and a basis weight of 500 g / m ² (model number PF040) manufactured by ADVANTEC, which are commercially available as a fiber layer, were prepared.
A card method through-air non-woven fabric having a basis weight of 200 g / m ² , a thickness of 5 mm, and a width of 1000 mm was used as a base material (here, the sheath-core type heat-fusible conjugate fiber manufactured in Example 1 was used).
Using these fiber layers and base materials, they are laminated so as to be fiber layer / base material layer / base material layer / fiber layer / base material layer / base material layer / fiber layer and cut into a 63 mm diameter circle to absorb sound. A measurement sample was prepared. When the normal incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (integrated value S from 200 Hz to 1000 Hz) was evaluated, it was 397.4, which was favorable.

[Comparative Example 1]
The substrate was peeled from the fiber layer obtained as the fiber layer under the same conditions as in Example 1. The average fiber diameters were 0.7 μm and 2 μm, respectively, and a nonwoven fabric with a basis weight of 80 g / m ² was used.
A card method through-air non-woven fabric having a basis weight of 200 g / m ² , a thickness of 5 mm, and a width of 1000 mm was used as a base material (here, the sheath-core type heat-fusible conjugate fiber manufactured in Example 1 was used).
Using these fiber layers and the base material, they were laminated so as to be base material layer / fiber layer / fiber layer / fiber layer / base material layer, and cut into a 63 mm diameter circle to prepare a sample for measuring sound absorption coefficient. When the normal incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (integrated value S from 200 Hz to 1000 Hz) was evaluated, it was 114.8, which was poor.

  A summary of Examples 1 to 3 and Comparative Example 1 is shown in Table 1.

  Since the laminated sound-absorbing material of the present invention is particularly excellent in the sound-absorbing property in the low-frequency region, it can be used as a sound-absorbing material in a field where noise in the low-frequency region is a problem. Specifically, as sound-absorbing material used for ceilings, walls, floors, etc. of houses, sound-proofing walls such as highways and railway lines, sound-proofing materials for home appliances, and sound-absorbing materials arranged in various parts of vehicles such as railways and automobiles Can be used

Claims (6)

A laminated sound-absorbing material comprising a plurality of fiber layers and a base material layer interposed between the fiber layers and the fiber layers,
The laminated sound absorbing material includes at least three fiber layers,
Each fiber layer is composed of fibers having a fiber diameter of 500 nm or more and less than 35 μm,
And a basis weight of 10 to 500 g / m ² ,
The base material layer has a basis weight of 10 g / m ² or more, a thickness of 0.1 mm or more,
The base material layer is at least one selected from the group consisting of a nonwoven fabric and a woven fabric.
Laminated sound absorbing material. The laminated sound-absorbing material according to claim 1, wherein the fiber layer has a basis weight of 10 to ²⁰⁰ g / m ² . The group forming the fiber layer is made of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polytetrafluoroethylene, polyvinylidene fluoride, nylon 6.6, polyacrylonitrile, polystyrene, polyurethane, polysulfone and polyvinyl alcohol. The laminated sound-absorbing material according to claim 1 or 2, which is at least one selected from the group consisting of: The base material contained in the base material layer is a nonwoven fabric made of at least one selected from the group consisting of polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene fiber and polypropylene fiber, and the basis weight of the base material is 10 to 500 g / it is m ^2, and stacked sound-absorbing material according to any one of claims 1 to 3. In the normal incidence sound absorption rate measurement method (200 to 1000 Hz), the sound absorption rate from 200 Hz to 3200 Hz is measured at intervals of 1 Hz, and the obtained curve is f (x), and the integrated value from 200 Hz to 1000 Hz. The laminated sound-absorbing material according to any one of claims 1 to 4, wherein S is a range satisfying the following formula.

In the normal incidence sound absorption rate measurement method (200 to 1000 Hz), the sound absorption rate from 200 Hz to 3200 Hz is measured at intervals of 1 Hz, and the obtained curve is f (x), and the integrated value from 200 Hz to 1000 Hz. The laminated sound-absorbing material according to any one of claims 1 to 4, wherein S is a range satisfying the following formula.

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