JP6912753B2 - Laminated sound absorbing material containing ultrafine fibers - Google Patents

Description

The present invention relates to a sound absorbing material having a laminated structure, which is composed of ultrafine fibers.

A sound absorbing material is a product having a function of absorbing sound, and is widely used in the fields of construction and automobiles. It is known to use a non-woven fabric as a material constituting the sound absorbing material. For example, Patent Document 1 discloses a composite non-woven fabric web containing 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 made by mixing two kinds of fibers having different median diameters called submicron fibers and microfibers, and by changing the mixing ratio, the gradient of the mixing ratio in the thickness direction. To obtain an inhomogeneous fiber mixture. In a typical embodiment, it is disclosed that by forming a microfiber stream and by forming a submicron fiber stream separately and adding it to the microfiber stream, a web made of a mixture of different fibers can be formed. ..

Further, Patent Document 2 includes a support layer and a submicron fiber layer laminated on the support layer as a multi-layer article having sound absorbing properties, and the submicron fiber layer has a central fiber diameter of less than 1 μm and an average. It is disclosed that the fiber diameter is in the range of 0.5 to 0.7 μm and is formed by a molten film fibrillation method or an electrospinning method. In the examples of Patent Document 2, ^{a polypropylene spunbonded non-woven fabric having a basis weight (grain) of 100 g / m 2} and a diameter of about 18 μm is used as a support layer, and a grain of 14 to 50 g / m ² and an average fiber diameter of about 0 are placed on the support layer. A laminated article in which .56 μm submicron polypropylene fibers are laminated is disclosed. In yet another embodiment, a multilayer article in which an electrospun polycaprolactone fiber having a ^{grain size of 6 to 32 g / m 2} and an average fiber diameter of 0.60 μm is laminated on a polyester card-treated web having a grain size of ^{62 g / m 2 is disclosed.} Has been done. The multilayer article produced in the examples has been measured for sound absorption characteristics and has been shown to have sound absorption characteristics superior to those of the support alone.

Patent Document 3 is a laminated sound-absorbing non-woven 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 (grain) up to a diameter of 600 nm. ) Those formed by a nanofiber layer of 0.1 to 5 g / m ^{2 are disclosed.} The nanofiber layer is typically produced by electrospinning, while the substrate layer is a fiber woven fabric with a diameter of 10 to 45 μm and a basis weight of 5 to 100 g / m ² , and yet another layer may be laminated. Is disclosed. It is also disclosed that the laminate may be further laminated to reach an appropriate thickness and basis weight.

Patent Document 4 discloses a non-woven fabric structure made of nanofibers and having excellent sound absorbing characteristics. The non-woven fabric structure of Patent Document 4 includes a fiber body containing nanofibers having a fiber diameter of less than 1 μm, and the thickness of the fiber body is 10 mm or more. Further, it is disclosed that the fibrous body may be supported by a support and may have a structure in which the fibrous body and the support are repeatedly laminated. It is disclosed that the nanofibers are formed by, for example, the melt blown method, and in the examples, ^{a layer of nanofibers having a fiber diameter of 0.5 μm and a grain size of 350 g / m 2 is formed on a polypropylene spunlace non-woven fabric which is a support.} Has been done.

Japanese Patent Application Laid-Open No. 2011-508113 Japanese Unexamined Patent Publication No. 2014-15042 Japanese Patent Application Laid-Open No. 2008-537798 Japanese Unexamined Patent Publication No. 2016-1214226

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

The inventor has made repeated studies to solve the above-mentioned problems. As a result, the laminated sound absorbing material including the base material layer and the fiber layer contains one or more fiber layers having a specific range of fiber diameters and textures, and further has one or more film structures, thereby solving the above-mentioned problems. We found that it could be solved and completed the present invention.

［７］垂直入射吸音率測定法において、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までの吸音率を積分した値Ｓが、下記式を満たす範囲である、［１］〜［５］のいずれか１項に記載の積層吸音材。

［８］［１］〜［７］のいずれか１項に記載の積層吸音材において、前記繊維層を構成する繊維が、ポリフッ化ビニリデン、ポリフッ化ビニリデンの共重合体、ナイロン６，６、ポリアクリロニトリル、ポリスチレン、ポリウレタン、ポリスルフォンおよびポリビニルアルコールからなる群から選ばれる１種以上の高分子を含む溶液を電界紡糸することによって作り出されることを特徴とする、積層吸音材の製造方法。 The present invention has the following configurations.
[1] A laminated sound absorbing material containing a fiber layer and a base material layer.
The fibrous layer, the included one or more layers during lamination sound absorbing material made of a fiber having an average fiber diameter of less than 450 nm, a basis weight is ^{0.1g / m 2 ~25g / m 2} ,
The base material layer is contained in one or more layers in the laminated sound absorbing material, and is composed of one or more selected from the group consisting of a non-woven fabric made of fibers having an average fiber diameter of 500 nm to 1 mm, a woven fabric, and paper, and has a texture of 1 g. / M ² or more,
Further, the laminated sound absorbing material is a laminated sound absorbing material having one or more layers of a film structure.
[2] The laminated sound absorbing material according to [1], wherein the thickness of the film structure is 10 μm or more and less than 500 μm.
[3] The laminated sound absorbing material according to [1] or [2], wherein the material of the membrane structure is one or more selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate and metal.
[4] The base material layer is a non-woven fabric made of one or more selected from the group consisting of polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene fibers and polypropylene fibers, and the base material layer has a texture of 1 to 300 g / m. ^2. The laminated sound absorbing material according to any one of [1] to [3].
[5] One or more of the fibers forming the fiber layer selected from the group consisting of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, nylons 6 and 6, polyacrylonitrile, polystyrene, polyurethane, polysulphon and polyvinyl alcohol. The laminated sound absorbing material according to any one of [1] to [4].
[6] In the vertical incident sound absorption coefficient measurement method, the sound absorption coefficient from 200 Hz to 3200 Hz was measured at 1 Hz intervals, and the sound absorption coefficient from 200 Hz to 1000 Hz was integrated when the obtained curve was f (x). The laminated sound absorbing material according to any one of [1] to [5], wherein the value S is in a range satisfying the following formula.

[7] In the vertical incident sound absorption coefficient measurement method, the sound absorption coefficient from 200 Hz to 3200 Hz was measured at 1 Hz intervals, and the sound absorption coefficient from 200 Hz to 1000 Hz was integrated when the obtained curve was f (x). The laminated sound absorbing material according to any one of [1] to [5], wherein the value S is in a range satisfying the following formula.

[8] In the laminated sound absorbing material according to any one of [1] to [7], the fibers constituting the fiber layer are polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, nylons 6, 6, and poly. A method for producing a laminated sound absorbing material, which is produced by electrospinning a solution containing one or more polymers selected from the group consisting of acrylonitrile, polystyrene, polyurethane, polysulphon and polyvinyl alcohol.

According to the present invention having the above-described configuration, by having the film structure in the laminated sound absorbing material, it is possible to realize high sound absorbing property with a small number of layers, and it is possible to reduce the thickness of the sound absorbing material. Further, according to the present invention having the above-described configuration, a 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 has a peak of sound absorbing characteristics in a region lower than that of the conventional sound absorbing material, 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, the road noise is said to be about 100 to 500 Hz, and the 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. Further, since the laminated sound absorbing material of the present invention is lighter than the sound absorbing material made of a porous material, glass fiber, etc., it is possible to reduce the weight and space of the member, and this point is particularly suitable for the automobile field. It is useful as a sound absorbing material.

It is a graph which shows the sound absorption characteristic of the Example (Example 7) and the comparative example (Comparative Example 1) of this invention.

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 fiber layer and a base material layer, and the fiber layer is composed of fibers containing one or more layers in the laminated sound absorbing material and having an average fiber diameter of less than 450 nm. basis weight of the fiber layer is ^{0.1g / m 2 ~25g / m 2} . The base material layer is one or more selected from the group consisting of non-woven fabrics and woven fabrics made of fibers having an average fiber diameter of 500 nm to 1 mm, and paper, which are contained in one or more layers in the laminated sound absorbing material. Is 1 g / m ² or more. Further, the laminated sound absorbing material of the present invention is characterized by having one or more layers of a film structure in addition to the above.

In the laminated sound absorbing material, the fiber layer is a fiber aggregate composed of ultrafine fibers having an average fiber diameter of less than 450 nm, and one or more layers are contained in the laminated sound absorbing material, preferably 1 to 6 layers, more preferably. Contains 1 to 3 layers. The one-layer fiber layer may be composed of one fiber aggregate, or a plurality of fiber aggregates are included in the one-layer fiber layer, and one fiber layer is formed from the plurality of fiber aggregates. It may be configured.
When there are two or more fiber layers, another layer (that is, a base material layer or a film structure) is interposed between the fiber layers, but the other layer is one layer. It may have two or more layers.

In the laminated sound absorbing material, the base material layer includes one or more layers, preferably 2 to 6 layers, and more preferably 2 to 4 layers. The base material layer has a function of retaining the entire structure of the laminated sound absorbing material. In particular, it supports the fiber layer, which is a layer of ultrafine fibers, and also acts as an intervening layer between the fiber layer and the fiber layer or between the fiber layer and the film structure to secure an appropriate interlayer distance. Have.

The laminated sound absorbing material contains one or more layers, preferably one to three layers, and more preferably one to two layers.

Each of the fiber layer, the base material layer and the film structure contained in the laminated sound absorbing material may be one type each, but may include two or more types of fiber layers, the base material layer and the film structure. Further, the laminated sound absorbing material of the present invention may include a structure other than the fiber layer, the base material layer and the film structure as long as the effects of the present invention are not impaired. For example, a further fiber layer (which may be one layer or two or more layers), a printing layer, a foam, a mesh, a woven fabric, etc., which are outside the range specified in the present invention, may be included. It may also contain an adhesive, a clip, a suture, or the like for connecting the layers.

Each layer constituting the laminated sound absorbing material may or may not be physically and / or chemically bonded. A part of the layers of the laminated sound absorbing material may be bonded and a part of the laminated sound absorbing material may not be bonded. Adhesion is carried out, for example, by heating in the fiber layer forming step or as a post-step to melt some of the fibers constituting the fiber layer and fuse the fiber layer to another layer to bond the fiber layer to another. It may be adhered to the layer. It is also possible to apply an adhesive to the surface of the layer to bond the layers.

The thickness of the laminated sound absorbing material is not particularly limited as long as the effect of the present invention can be obtained, but can be, for example, 0.1 to 50 mm, preferably 0.3 to 40 mm, preferably 0.3 to 25 mm. If there is, it is more preferable from the viewpoint of space saving. The thickness of the laminated sound absorbing material means the total thickness of the fiber layer, the base material layer, and the membrane structure, and when an exterior body such as a cartridge or a lid is attached, the thickness of that portion is included. Make it not exist.

(Fiber layer)
The fiber layer contained in the laminated sound absorbing material of the present invention is a fiber aggregate composed of fibers having an average fiber diameter of less than 450 nm. If the average fiber diameter is less than 450 nm, high sound absorption can be obtained, which is preferable, and if it is less than 420 nm, higher sound absorption can be obtained, which is more preferable. The lower limit of the average fiber diameter is not particularly limited, but if the average fiber diameter is 10 nm or more, the workability is excellent and it is easy to use. The average fiber diameter can be measured by a known method. For example, it is a value obtained by measuring or calculating from an enlarged photograph of the surface of the fiber layer, and a detailed measuring method is described in detail in Examples.

In the fiber layer contained in the laminated sound absorbing material of the present invention, one fiber layer may be composed of one fiber aggregate, or a plurality of fiber aggregates are contained in one fiber layer, and the fiber aggregate is contained. The layers of the body may be superposed to form one fiber layer.

Basis weight of the fiber layer is preferably 0.1~25g / ^{m 2,} further preferably 0.3 to 20 g / ^{m 2.} If the basis weight is 0.1 g / m ² or more, the control of flow resistance due to the density difference between the fiber layer and the fibers constituting the base material layer is good, and ^{if it is less than 25 g / m 2} , the warp is large as a sound absorbing material. A sound absorbing material having excellent practicality can be obtained.

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 a texture in the above range, but is a melt-blown non-woven fabric, a non-woven fabric of ultrafine fibers formed by an electric field spinning method, or the like. Is preferable. According to the electrospinning method, ultrafine fibers can be efficiently laminated on the base material layer as a fiber aggregate. Details of the electrospinning method will be described in the manufacturing method.

The resin constituting the fiber used for the fiber aggregate is not particularly limited as long as the effects of the invention can be obtained, and for example, polyolefins such as polypropylene and polyethylene, polyurethane, polylactic acid, acrylic resin, polyethylene terephthalate and polybutylene terephthalate, etc. Polyesters, nylon 6, nylon 6, 6, nylon (amide resin) such as nylon 12, polyphenylene sulfide, polyvinyl alcohol, polystyrene, polysulphon, liquid crystal polymers, polyethylene-vinyl acetate copolymer, polyacrylonitrile, polyvinylidene fluoride Examples thereof include copolymers of polyvinylidene fluoride such as vinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene. Among these, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene, nylon 6,6, polyacrylonitrile, polystyrene, polyurethane, polysulfone and polyvinyl alcohol are soluble in various solvents in the electrospinning method. , More preferred.
The fiber preferably contains one kind of the above-mentioned resin, and may contain two or more kinds.

Further, the fiber may contain various additives other than the resin. Additives that can be added to the resin include, for example, fillers, stabilizers, plasticizers, adhesives, adhesion promoters (eg, silanes and titanates), silica, glass, clay, talc, pigments, colorants, etc. Examples include antioxidants, fluorescent whitening agents, antibacterial agents, surfactants, flame retardants, and fluoropolymers. One or more of the additives may be used to reduce the weight and / or cost of the resulting fibers and layers, adjust the viscosity, or modify the thermal properties of the fibers. Alternatively, various physical characteristic activities derived from the properties of the additive may be imparted, including electrical properties, optical properties, density properties, liquid barrier or adhesive properties.

(Base 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. In the laminated sound absorbing material of the present invention, the fiber layer is a fiber aggregate formed of fibers having an extremely fine fiber diameter of less than 450 nm, and therefore has low strength (rigidity). Therefore, the base material layer and the film structure substantially bear the strength of the laminated sound absorbing material.

The base material layer is not particularly limited as long as it has breathability and a fiber layer can be laminated on at least one of the surfaces thereof, and a structure such as a non-woven fabric, a woven fabric, paper, or a resin foam can be used. .. In particular, it is preferably one or more of non-woven fabric, woven fabric, and paper, and more preferably non-woven fabric. The laminated sound absorbing material may contain one type of base material layer, and it is also preferable to include two or more types of base material layers.

When the base material layer is a non-woven fabric composed of fibers made of resin, melt-blown non-woven fabric, spunlace non-woven fabric, spunbond non-woven fabric, through-air non-woven fabric, thermal bond non-woven fabric, needle punch non-woven fabric and the like can be used, and have desired physical properties and functions. Can be selected as appropriate.

As the resin constituting the fibers of the non-woven fabric of the base material layer, a thermoplastic resin can be used, and examples thereof include a polyolefin resin, a polyester resin such as polyethylene terephthalate, and a polyamide resin. Examples of the polyolefin resin include homopolymers such as ethylene, propylene, butene-1, or 4-methylpentene-1, and other α-olefins, that is, ethylene, propylene, butene-1, penten-1, and the like. It is a random or block copolymer with one or more of hexene-1 or 4-methylpentene-1, or a copolymer obtained by combining them, or a mixture thereof. Polyamide-based resins include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 6, 6, nylon 6, 10, polymethaxylylene adipamide, polyparaxylylene decaneamide, and polybiscyclohexylmethanedecaneamide. Alternatively, these copolyamides and the like can be mentioned. Examples of the polyester-based 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 more of polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene fiber and polypropylene fiber.
When the base material layer is a woven fabric, fibers composed of the same resin can be used.

As the fiber constituting the non-woven fabric of the base material layer, a fiber containing only one component can be used, but when the effect of fusion of the intersections of the fibers is taken into consideration, a composite component of the low melting point resin and the high melting point resin is used. It is also preferable to use fibers made of, that is, composite fibers made 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. It is also preferable to use a mixed fiber having two or more components having different melting points as the fiber constituting the non-woven fabric of the base material layer. The mixed fiber means a fiber in which a fiber made of a high melting point resin and a fiber made of a low melting point resin are independently present and mixed. Similar fibers can be used when the base material is a woven fabric.

The fiber diameter of the fibers constituting the non-woven fabric of the base material layer is not particularly limited, but those having a fiber diameter of 500 nm to 1 mm can be used. The fiber diameter of 500 nm to 1 mm means that the average fiber diameter is within this numerical range. If the fiber diameter is 500 nm or more, the flow resistance due to the density difference between the fibers constituting the non-woven fabric of the fiber layer and the base material layer can be controlled, and if it is less than 1 mm, versatility is not lost. It will also be easy to obtain. When the fiber diameter is 1.0 to 100 μm, it is more preferable because the flow resistance due to the density difference of the fibers constituting the non-woven fabric of the fiber layer and the base material layer can be controlled and 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. Similar fibers can be used when the base material is a woven fabric.

When the base material layer is a woven fabric, a woven fabric obtained by a weave such as plain weave, open plain weave, twill weave, satin weave, and imitation weave can be used, and can be appropriately selected depending on desired physical properties and functions. As the woven fabric, for example, a glass cloth manufactured by using glass yarn, or a plain weave or twill weave mesh of fibers made of metal wire or resin can be used.

When the base material layer is paper, any paper produced by sticking plant fibers or other fibers can be used without particular limitation. Paper can be produced by a wet papermaking method using, for example, plant fibers such as pulp, fibers made of resin, and glass fibers as raw materials.

When the base material layer is a resin foam, any resin foam in which gas is finely dispersed in the resin and molded into a foamy or porous shape can be used without particular limitation. As the resin foam, for example, flexible polyurethane foam, hard polyurethane foam, polystyrene foam, silicone foam, polyvinyl chloride foam, acrylic foam, and urea foam can be used.

The base material layer may be included as a layer located on the outermost surface of the laminated sound absorbing material. The one-layer base material layer may be composed of only one non-woven fabric, or two or more non-woven fabrics may be laminated to form one base material layer. By laminating two or more non-woven fabrics, there is an advantage that the interlayer distance between the fiber layer and the film structure can be controlled by the thickness of the base material layer.

Basis weight of the base layer may be any 1 g / ^{m 2} or more, preferably 1 to 300 g / ^{m 2,} and more preferably 15~300g / ^{m 2.} If the basis weight of the base material layer ^{is less than 1 g / m 2} , the strength required as a sound absorbing material may not be obtained.

In the present invention, the total thickness of the base material layer is not particularly limited, but since the thickness of the base material layer often occupies most of the thickness of the laminated sound absorbing material, from the viewpoint of space saving. It is preferably 0.1 to 60 mm, more preferably 0.1 to 30 mm.

The thickness of one structure constituting one base material layer can be, for example, 20 μm to 20 mm, more preferably 30 μm to 10 mm. If the thickness of the base material layer is 20 μm or more, wrinkles do not occur, handling is easy, productivity is good, and if the thickness of the base material layer is 20 mm or less, there is no risk of hindering space saving. The thickness of the base material layer of one layer is, in other words, the thickness of the layer that separates the layers (fiber layer and film structure) other than the base material layer. It is considered that high sound absorption and space saving can be achieved at the same time by making the thickness (interlayer distance) appropriate.

Various additives such as colorants, antioxidants, light stabilizers, UV absorbers, neutralizers, nucleating agents, lubricants, and antibacterial agents are used on the base material layer as long as the effects of the present invention are not impaired. Agents, flame retardants, plasticizers and other thermoplastics may be added. Further, the surface may be treated with various finishing agents, which may impart functions such as water repellency, antistatic property, surface smoothness, and abrasion resistance.

(Membrane structure)
The laminated sound absorbing material of the present invention is characterized by having one or more film structures in addition to the above-mentioned fiber layer and base material layer. The film structure used in the present invention is a non-breathable resin film, sheet or metal leaf, and the above-mentioned fiber layer and base material layer are breathable structures, whereas the film structure is a film. The structure is distinguished in that it is a non-breathable structure.

The film structure is preferably a resin film or sheet, and the resin constituting the film (sheet) is not particularly limited, but for example, a polyolefin resin such as polyethylene or polypropylene, nylon 4, nylon 6, nylon 7, etc. Of In addition, polyester resins such as polytetramethylene terephthalate, polybutyl terephthalate, polyethylene oxybenzoate, poly (1,4-dimethylcyclohexane terephthalate) or copolymers thereof can be mentioned.

The thickness of the film structure is not particularly limited as long as the effects of the present invention can be obtained, but it is preferably 10 μm or more and less than 500 μm. By using a film or sheet having a thickness of 10 to 500 μm, which is highly productive and easily available, the effect of the present invention that the productivity of the sound absorbing material as a whole can be improved and the production cost can be reduced and the sound absorbing characteristics are excellent can be obtained. .. As such a film structure, a film having a desired material and thickness may be produced and used, or a commercially available product may be used. Commercially available products include, for example, unstretched polypropylene film, biaxially stretched polypropylene film, uniaxially stretched film, polyester film, linear rodency polyethylene film, inflation film, polypropylene sheet, polyethylene sheet, polyester sheet, vinyl sheet, and Teflon (registered trademark). A sheet, aluminum foil, or the like having appropriate physical properties can be selected and used.

The position of the film structure in the laminated sound absorbing material is not particularly limited, and may be located inside the laminated structure or may be a layer exposed to the outside as the outermost layer, but is located at the outermost layer. It is more preferable that the structure is located on the outermost layer on the downstream side (the side far from the sound source). When the laminated sound absorbing material contains two or more film structures, it is preferable that one of them is arranged in the outermost layer on the downstream side. Although not bound by a specific theory, in the laminated sound absorbing material, by arranging a non-woven fabric having a relatively low density on the upstream side (the side close to the sound source) and arranging the membrane structure on the downstream side, It is considered that a thin sound absorbing material having a higher sound absorbing function and a higher sound absorbing function can be realized.

(Sound absorption characteristics of laminated sound absorbing material)
The laminated sound absorbing material of the present invention is particularly excellent in sound absorbing property in a low frequency region (frequency region of 1000 Hz or less). The laminated sound absorbing material of the present invention exhibits a sound absorbing characteristic different from that of the conventional sound absorbing material, which is particularly excellent in sound absorbing property in the 400 Hz to 1000 Hz region. Although not bound by a specific theory, the laminated sound absorbing material of the present invention uses the density difference between the fiber layer and the base material layer to control the flow resistance of sound waves, and as a result of installing a film structure, It is considered that the performance of excellent absorption in the low frequency region can be obtained.
The method for evaluating sound absorption is described in detail in Examples.

(Manufacturing method of laminated sound absorbing material)
The method for producing the laminated sound absorbing material is not particularly limited, and for example, a step of producing a laminated body of a fiber layer and a base material layer in which a fiber layer is formed on a base material layer, a plurality of laminated bodies, and a film structure are predetermined. It can be obtained by a manufacturing method including a step of superimposing and integrating in the order and the number of sheets.

When a non-woven fabric is used as the base material layer, the non-woven fabric may be produced and used by a known method, or a commercially available non-woven fabric may be selected and used. It is preferable to use an electric field spinning method for the step of forming the fiber layer on the base material layer. 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 extruding a spinning solution from a nozzle and applying an electric field to spin, a method of foaming the spinning solution and applying an electric field to spin, a method of guiding the spinning solution to the surface of a cylindrical electrode and applying an electric field to spin. You can mention how to do it. In the present invention, a non-woven fabric or the like to be a base material layer can be inserted on the collector, and fibers can be accumulated on the base material layer to form a fiber layer.

The spinning solution is not particularly limited as long as it has spinnability, but is preferably a solution containing a polymer. For example, a solution in which a polymer resin is dispersed in a solvent or a polymer resin is dissolved in a solvent. A solvent, a polymer resin melted by heat or laser irradiation, or the like can be used.

Examples of the solvent for dispersing or dissolving the resin include water, methanol, ethanol, propanol, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, toluene and xylene. , Ppyridine, formic acid, acetic acid, tetrahydrofuran, dichloromethane, chloroform, 1,1,2,2-tetrachloroethane, 1,1,1,3,3,3-hexafluoroisopropanol, trifluoroacetic acid and mixtures thereof. be able to. The mixing ratio when mixed and used is not particularly limited, and can be appropriately set in consideration of the desired spinnability, dispersibility, and physical properties of the obtained fiber.

A surfactant may be further contained in the spinning solution for the purpose of improving the stability and fiber forming property of electrospinning. Examples of the surfactant include anionic surfactants such as sodium dodecyl sulfate, cationic surfactants such as tetrabutylammonium bromide, and nonionic surfactants 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. When it is 5% by weight or less, the effect suitable for use can be improved, which is preferable. In addition, components other than the 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 for preparing the spinning solution is not particularly limited, and examples thereof include methods such as stirring and ultrasonic treatment. Further, the order of mixing is not particularly limited, and they may be mixed at the same time or sequentially. The stirring time when the spinning solution is prepared by stirring is not particularly limited as long as the resin is uniformly dissolved or dispersed in the solvent, and may be stirred for, for example, about 1 to 24 hours.

In order to obtain fibers by electrospinning, the viscosity of the spinning solution is preferably adjusted in the range of 10 to 10,000 cP, more preferably in the range of 50 to 8,000 cP. When the viscosity is 10 cP or more, spinnability for forming fibers is obtained, and when the viscosity is 10,000 cP or less, the spinning solution can be easily discharged. When the viscosity is in the range of 50 to 8,000 cP, good spinnability can be obtained in a wide range of spinning conditions, which is more preferable. The viscosity of the spinning solution can be adjusted by appropriately changing the molecular weight and concentration of the resin, the type of solvent, and the mixing ratio.

The temperature of the spinning solution may be at room temperature, or may be heated and cooled before spinning. Examples of the method of discharging the spinning solution include a method of discharging the spinning solution filled in the syringe into the syringe from the nozzle using a pump. The inner diameter of the nozzle is not particularly limited, but is preferably in the range of 0.1 to 1.5 mm. The discharge amount is not particularly limited, but is preferably 0.1 to 10 mL / hr.

The method of applying an electric field to the spinning solution is not particularly limited as long as an electric field can be formed in the nozzle and the collector. For example, a high voltage may be applied to the nozzle and the collector may be grounded as a ground. The applied voltage is not particularly limited as long as the fibers are formed, but is preferably in the range of 5 to 100 kV. The distance between the nozzle and the collector is not particularly limited as long as the fibers are formed, but is preferably in the range of 5 to 50 cm.

The method for laminating and integrating a plurality of laminated bodies composed of a base material layer and a fiber layer and a separately prepared film structure obtained as described above is not particularly limited, and the laminated bodies are laminated without being bonded. It is also possible to adopt various bonding methods, that is, thermocompression bonding with a heated flat roll or embossed roll, bonding with a hot melt agent or a chemical adhesive, heat bonding with circulating hot air or radiant heat, and the like. From the viewpoint of suppressing deterioration of the physical properties of the fiber layer containing the ultrafine fibers, heat treatment using circulating hot air or radiant heat is particularly preferable. In the case of thermocompression bonding with flat rolls or embossed rolls, it is necessary to adjust the processing temperature so that the fiber layer does not melt and form a film, or the area around the embossed point is not damaged. Is. Further, in the case of adhesion with a hot melt agent or a chemical adhesive, it is necessary to process the components so that the interfiber gaps of the fiber layer are not filled and the performance is not deteriorated. On the other hand, when integrated by heat treatment with circulating hot air or radiant heat, damage to the fiber layer is small and the integration can be performed with sufficient delamination strength, which is preferable. When integrated by heat treatment with circulating hot air or radiant heat, it is not particularly limited, but it is preferable to use a non-woven fabric and a laminate made of heat-sealing composite fibers.

Hereinafter, the present invention will be described in more detail by way of examples, but the following examples are for purposes of illustration only. The scope of the present invention is not limited to this embodiment.
The measurement method or definition of the physical property values used in the examples is shown below.
<Average fiber diameter>
The ultrafine fibers were observed using a scanning electron microscope SU8020 manufactured by Hitachi High-Technologies Corporation, and the diameters of 50 ultrafine fibers were measured using image analysis software. The average value of the fiber diameters of 50 ultrafine fibers was taken as the average fiber diameter.

<Measurement of sound absorption coefficient>
The sound absorption coefficient is measured by collecting a sample with a diameter of 63 mm from each laminate, laminating under each condition, and then using a vertical incident sound absorption coefficient measuring device "TYPE 4206 manufactured by Bruel & Care Co., Ltd." in accordance with ASTM E 1050 and a frequency of 200. The vertical incident sound absorption coefficient when a plane sound wave was vertically incident on the test piece at ~ 3200 Hz was measured.
<Sound absorption in the low frequency range>
When the sound absorption coefficient from 200 Hz to 3200 Hz is measured at 1 Hz intervals and the obtained curve is f (x), the integrated value S of the sound absorption coefficient from 200 Hz to 1000 Hz can be obtained by the following formula.

The integrated value S indicates the sound absorbing performance in the frequency range of 200 to 1000 Hz, and if the numerical value is high, it is judged that the sound absorbing property is high. When the S value exceeds 170, the sound absorption in the low frequency region is evaluated as good, and when it is less than 170, the sound absorption is evaluated as poor.

<Space saving>
When the thickness of the laminated sound absorbing material was less than 25 mm, it was evaluated as good (◯), and when the thickness was 25 mm or more, it was evaluated as insufficient space saving (x).

[Preparation of base material layer A]
High-density polyethylene "M6900" (MFR 17 g / 10 minutes) made of KEIYO polyethylene was used as the high-density polyethylene resin, and polypropylene homopolymer "SA3A" (MFR = 11 g / 10 minutes) made by Nippon Polypro was used as the polypropylene resin. , A sheath-core type heat-sealing composite fiber having a fiber diameter of 22 μm made of a high-density polyethylene resin and a core component of polypropylene resin was produced by a heat-melt spinning method.
Using this sheath-core type heat-sealing composite fiber, ^{a card-method through-air non-woven fabric having a basis weight of 200 g / m 2} and a thickness of 5 mm was produced and used as a base material layer A.

[Example 1]
Arkema's polyvinylidene fluoride-hexafluoropropylene (hereinafter abbreviated as "PVDF-HFP") resin, Kynar (trade name) 3120, is used as a co-solvent of N, N-dimethylacetamide and acetone (60/40 (60/40 (hereinafter abbreviated as "PVDF-HFP")). It was dissolved in w / w)) at a concentration of 15% by mass to prepare a spinning solution. A polyethylene terephthalate through-air non-woven fabric having a grain size of 18 g / m ² , a thickness of 60 μm, and a width of 1000 mm is prepared as a base material layer B, and the PVDF-HFP solution is electrospun onto the polyethylene terephthalate through-air non-woven fabric. A laminate consisting of two layers, a material layer B and a fiber layer made of PVDF-HFP ultrafine fibers, was prepared. The conditions for electric field spinning were that a 24 G needle was used, the supply amount of the single-hole solution was 3.0 mL / h, the applied voltage was 35 kV, and the spinning distance was 17.5 cm. The basis weight of the PVDF-HFP ultrafine fiber layer in the obtained laminate was 1.0 g / m ² , the average fiber diameter was 180 nm, and the melting temperature was 168 ° C. The laminate is punched into a circle with a diameter of 63 mm, and two laminates, a grain of 200 g / m ² , a thickness of 5 mm, a card method through-air non-woven fabric (base material layer A), and a resin film structure (25SS: manufactured by OJK Co., Ltd.) Product name "25SS", thickness 25 μm, unstretched polypropylene film) is prepared to form a fiber layer / base material layer B / base material layer A / fiber layer / base material layer B / base material layer A / membrane structure. These were superposed to prepare a sample for measuring the sound absorption coefficient. The interlayer distance between the fiber layer and the fiber layer and between the fiber layer and the film structure was 5.1 mm (the thickness of the base material layer, which is the sum of the thicknesses of the base material layer B and the base material layer A). The laminated base material layer B / base material layer A was regarded as one base material layer.
When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 187, which was good.

[Example 2]
The same procedure as in Example 1 was carried out except that the fibers layer / base material layer B / base material layer A / film structure / base material layer B / base material layer A / film structure were superposed. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 5.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 201, which was good.

[Example 3]
Examples except that the fibers layer / base material layer B / base material layer A / base material layer A / fiber layer / base material layer B / base material layer A / base material layer A / film structure were overlapped. It was carried out in the same manner as in 1. The interlayer distance between the fiber layer and the fiber layer and between the fiber layer and the film structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 269, which was good.

[Example 4]
Except for superimposing the fiber layer / base material layer B / base material layer A / base material layer A / film structure / base material layer B / base material layer A / base material layer A / film structure. It was carried out in the same manner as in Example 1. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 299, which was good.

[Example 5]
A resin film structure (product name "80A" manufactured by OJK Co., Ltd., thickness 80 μm, unstretched polypropylene film) is prepared as the film structure, and the fiber layer / base material layer B / base material layer A / fiber layer / This was carried out in the same manner as in Example 1 except that the base layer B / base layer A / film structure was overlapped. The interlayer distance between the fiber layer and the fiber layer and between the fiber layer and the film structure was 5.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 270, which was good.

[Example 6]
The same procedure as in Example 5 was carried out except that the fibers layer / base material layer B / base material layer A / film structure / base material layer B / base material layer A / film structure were superposed. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 5.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 204, which was good.

[Example 7]
Examples except that the fibers layer / base material layer B / base material layer A / base material layer A / fiber layer / base material layer B / base material layer A / base material layer A / film structure were overlapped. It was carried out in the same manner as in 5. The interlayer distance between the fiber layer and the fiber layer, and between the film structure and the film structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 300, which was good.

[Example 8]
Except for superimposing the fiber layer / base material layer B / base material layer A / base material layer A / film structure / base material layer B / base material layer A / base material layer A / film structure. It was carried out in the same manner as in Example 5. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 316, which was good.

[Example 9]
As a film structure, a resin film structure 400P (product name "400P" manufactured by OJK Co., Ltd., thickness 400 μm, polypropylene sheet) is prepared, and a fiber layer / base material layer B / base material layer A / fiber layer / group is prepared. It was carried out in the same manner as in Example 1 except that the material layer B / base material layer A / film structure was overlapped. The interlayer distance between the fiber layer and the fiber layer and between the fiber layer and the film structure was 5.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 191 which was good.

[Example 10]
The same procedure as in Example 9 was carried out except that the fibers layer / base material layer B / base material layer A / film structure / base material layer B / base material layer A / film structure were superposed. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 5.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 245, which was good.

[Example 11]
Examples except that the fibers layer / base material layer B / base material layer A / base material layer A / fiber layer / base material layer B / base material layer A / base material layer A / film structure were overlapped. It was carried out in the same manner as in 9. The interlayer distance between the fiber layer and the fiber layer and between the fiber layer and the film structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 218, which was good.

[Example 12]
Except for superimposing the fiber layer / base material layer B / base material layer A / base material layer A / film structure / base material layer B / base material layer A / base material layer A / film structure. It was carried out in the same manner as in Example 9. The interlayer distance between the fiber layer and the membrane structure and between the membrane structure and the membrane structure was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 383, which was good.

[Example 13]
As a film structure, a polyester film having a thickness of 100 μm: PET100 (product name “Lumilar” manufactured by Toray Co., Ltd.) is prepared, and the film structure / base material layer A / base material layer A / base material layer B / fiber layer It was carried out in the same manner as in Example 1 except that they were overlapped so as to be. The interlayer distance between the membrane structure and the fiber layer was 10.1 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 206, which was good.

[Example 14]
The same procedure as in Example 13 was carried out except that the base layer B / fiber layer / film structure / base material layer A / base material layer A / base material layer B / fiber layer were superposed. The interlayer distance between the fiber layers was 10.2 mm. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 250, which was good.

[Comparative Example 1]
The two-layer laminate obtained in Example 1 was cut out to a major axis diameter of 252 mm and a minor axis diameter of 63 mm, and mountain folds and valley folds were repeated at intervals of 10 mm in width to perform pleating. A paper frame having a width of 10 mm and a length of 197.8 mm was processed into a circular shape in the major axis direction to prepare a paper frame. A sample for measuring the sound absorption coefficient is fixed by fixing a commercially available silicon caulking material (chemical reaction type adhesive manufactured by Konishi Co., Ltd.) around the two-layer pleated laminate so that it fits within this paper frame. Obtained. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 50, and the sound absorption property in the low frequency region could not be obtained, which was a defect. rice field. The peak of the absorption characteristic was 3200 Hz or higher.

[Comparative Example 2]
A commercially available polypropylene resin non-woven fabric (Thinsulate T2203 manufactured by 3M, fiber diameter 0.7 μm to 4.0 μm, thickness 29 mm) was punched into a circle with a diameter of 63 mm to prepare a sample for sound absorption measurement. The vertical incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated. rice field.

[Comparative Example 3]
The same procedure as in Example 1 was carried out except that the base layer A / base layer B / fiber layer / fiber layer / base layer B / base layer A were superposed. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 55, and the sound absorption property in the low frequency region could not be obtained, resulting in a defect. there were.

[Comparative Example 4]
The same procedure as in Example 1 was carried out except that the fiber layer / base material layer B / base material layer A / base material layer A / base material layer B / fiber layer were superposed. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 142, and the sound absorption property in the low frequency region could not be obtained, resulting in a defect. there were.

[Comparative Example 5]
The same procedure as in Example 1 was carried out except that the fibers layer / base material layer B / base material layer A were superposed. When the vertically incident sound absorption coefficient was measured and the sound absorption property in the low frequency region (value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz) was evaluated, it was 59, and the sound absorption property in the low frequency region could not be obtained, resulting in a defect. there were.

Table 1 summarizes the structure, physical properties, and sound absorbing performance of the laminated sound absorbing materials of Examples 1 to 7.

Table 2 summarizes the structure, physical properties, and sound absorbing performance of the laminated sound absorbing materials of Examples 8 to 14.

Table 3 summarizes the structure, physical properties, and sound absorption performance of the laminated sound absorbing materials of Comparative Examples 1 to 5.

As shown in Tables 1 to 3, all of the laminated sound absorbing materials of Examples 1 to 14 of the present invention were excellent in sound absorbing property and space saving property in a low frequency region. On the other hand, Comparative Example 1 in which the laminated body was pleated had insufficient sound absorption in the low frequency region. Further, all of Comparative Example 3, Comparative Example 4, and Comparative Example 5 containing the fiber layer and the base material layer but not the film structure had insufficient sound absorption in the low frequency region. Comparative Example 2, which is a conventional product, was insufficient in both sound absorption and space saving in the low frequency region.
Further, FIG. 1 shows graphs of sound absorption characteristics of Example 7 and Comparative Example 1. Example 7 exhibits significantly higher sound absorption than Comparative Example 1 especially in the low frequency region (region of 1000 Hz or less).

Claims (8)

A laminated sound absorbing material containing a fiber layer and a base material layer.
The fibrous layer, the included one or more layers during lamination sound absorbing material made of a fiber having an average fiber diameter of less than 450 nm, a basis weight is ^{0.1g / m 2 ~25g / m 2} ,
The base material layer is contained in one or more layers in the laminated sound absorbing material, and is composed of one or more selected from the group consisting of non-woven fabrics and woven fabrics made of fibers having an average fiber diameter of 500 nm to 1 mm and paper, and has a texture of 1 g. / M ² or more,
Furthermore, the stacked sound-absorbing material, have a membrane structure 1 or more layers,
The membrane structure is arranged on the downstream side far from the sound source from the fiber layer.
The fibrous layer and membrane structure that is laminated via the base layer,
Laminated sound absorbing material. The laminated sound absorbing material according to claim 1, wherein the thickness of the film structure is 10 μm or more and less than 500 μm. The laminated sound absorbing material according to claim 1 or 2, wherein the material of the membrane structure is one or more selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, and metal. The base material layer is a non-woven fabric composed of one or more selected from the group consisting of polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene fibers and polypropylene fibers, and the base material layer has a texture of 1 to 300 g / m ² . , The laminated sound absorbing material according to any one of claims 1 to 3. The fiber forming the fiber layer is one or more selected from the group consisting of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, nylons 6 and 6, polyacrylonitrile, polystyrene, polyurethane, polysulphon and polyvinyl alcohol. The laminated sound absorbing material according to any one of claims 1 to 4. In the vertical incident sound absorption coefficient measurement method, when the sound absorption coefficient with a frequency x of 200 Hz to 3200 Hz is measured at 1 Hz intervals and the obtained curve is f (x), the value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz is The laminated sound absorbing material according to any one of claims 1 to 5, which is within the range satisfying the following formula.

In the vertical incident sound absorption coefficient measurement method, when the sound absorption coefficient with a frequency x of 200 Hz to 3200 Hz is measured at 1 Hz intervals and the obtained curve is f (x), the value S obtained by integrating the sound absorption coefficient from 200 Hz to 1000 Hz is The laminated sound absorbing material according to any one of claims 1 to 5, which is within the range satisfying the following formula.

In the laminated sound absorbing material according to any one of claims 1 to 7, the fibers constituting the fiber layer are polyvinylidene fluoride, a copolymer of polyvinylidene fluoride, nylon 6,6, polyacrylonitrile, polystyrene, polyurethane. , A method for producing a laminated sound absorbing material, which is produced by electrospinning a solution containing one or more polymers selected from the group consisting of polyvinylidene fluoride and polyvinyl alcohol.

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