WO2016103646A1

WO2016103646A1 - Sound-absorbing material

Info

Publication number: WO2016103646A1
Application number: PCT/JP2015/006267
Authority: WO
Inventors: 谷　直幸; 悠中嶋; 徹藤澤; 俊文名木野; 基畑中
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-12-25
Filing date: 2015-12-16
Publication date: 2016-06-30
Also published as: JP5866625B1; JP2016121426A

Abstract

The sound-absorbing material according to the present invention comprises a nonwoven-fabric structure including a fibrous object made up of entangled fibers. The fibers include nanofibers which are constituted of polypropylene and have a fiber diameter smaller than 1 µm. The fibrous object has a thickness of 20-36 mm. The fibrous object has a fiber density of 10 kg/m³ or higher but less than 50 kg/m³, and the content of the nanofibers in the fibrous object is 0.5 or higher in terms of ratio by mass. The sound-absorbing material has a sound absorption coefficient for 1-kHz sound of 0.59-0.84 and a sound absorption coefficient for 6-kHz sound of 0.80-0.96.

Description

Sound absorbing material

The present invention relates to a sound absorbing material.

In recent years, there is an increasing need for noise countermeasures in familiar environments such as in-car environments. As one of the countermeasures, a sound absorbing material is used, and as a kind of the sound absorbing material, for example, a structure (nonwoven fabric structure) made of nonwoven fabric fibers is used. The nonwoven fabric structure is used not only for sound absorbing materials but also for various applications. As the nonwoven fabric structure, a nonwoven fabric structure having a fiber body in which resin nanofibers having a fiber diameter of less than 1 μm are entangled is known (see, for example, Patent Documents 1 to 7). Among them, a nonwoven fabric structure in which the fibrous body has a thickness of 10 mm or more is known (see, for example, Patent Documents 3 to 7).

JP 2013-139655 A Japanese Unexamined Patent Publication No. 2014-111850 JP 2014-015042 A JP 2009-512578 A JP 2013-50397A Special table 2011-508113 gazette JP 2013-147771 A

The nonwoven fabric structure is expected to have various functions due to the fine fiber diameter of the nanofiber. However, the production of nanofibers is still more difficult than that of microfibers, and the structural conditions (for example, thickness, density, etc.) of the above-mentioned fibrous body using nanofibers have not been sufficiently studied. For example, regarding the thickness, none of the above-mentioned patent documents discloses knowledge about the function provided by the above-described fibrous body that is thicker than 10 mm.

Thus, although the non-woven fabric structure is expected to be used for various purposes, there is still room for study on the function expressed by the structural conditions of the non-woven fabric structure.

An object of the present invention is to provide a sound-absorbing material having excellent sound-absorbing characteristics using nanofibers.

The present invention is a sound-absorbing material including a nonwoven fabric structure having a fiber body in which fibers are entangled, and the fiber includes a nanofiber made of polypropylene having a fiber diameter of less than 1 μm, and the thickness of the fiber body Is 20 mm or more and 36 mm or less, the fiber density of the fiber body is 10 kg / m ³ or more and less than 50 kg / m ³ , and the content ratio of the nanofibers in the fiber body is 0.5 or more by mass ratio. And a sound-absorbing material having a sound absorption coefficient of 1 kHz sound of 0.59 or more and 0.84 or less and a sound absorption coefficient of 6 kHz sound of 0.80 or more and 0.96 or less.

The sound-absorbing material according to the present invention is superior in the sound-absorbing property of the sound in the low frequency range as compared with the non-woven structure including the fiber body made of microfiber. Moreover, the nonwoven fabric product containing this nonwoven fabric structure can express the expected function other than a sound absorption characteristic, and said outstanding sound absorption characteristic.

Drawing 1A is a figure showing typically the 1st mode of the nonwoven fabric structure concerning a 1st embodiment of the present invention, and Drawing 1B is a figure showing typically the 2nd mode of the above-mentioned nonwoven fabric structure. 1C is a diagram schematically showing a third aspect of the nonwoven fabric structure, FIG. 1D is a diagram schematically showing a fourth aspect of the nonwoven structure, and FIG. FIG. 7 is a diagram schematically showing a fifth aspect of the nonwoven fabric structure. It is a figure which shows the sound absorption characteristic of the

nonwoven fabric structures

1 and 2 and the nonwoven fabric structure C1. FIG. 3A is a scanning electron microscope (SEM) photograph showing a part of an example of a fiber body using nanofibers in the present invention at 200 times magnification, and FIG. 3B is a part of an example of the fiber body of 2000 It is a SEM photograph enlarged and shown twice. FIG. 4A is an SEM photograph showing a part of an example of a fiber body in which nanofibers and microfibers are mixed in the present invention at 200 times magnification, and FIG. 4B is a part of an example of the fiber body 2000 It is a SEM photograph enlarged and shown twice.

Embodiments of the present invention will be described below.
The sound absorbing material according to the present embodiment includes a nonwoven fabric structure. The nonwoven fabric structure has a fiber body in which fibers are entangled. The fiber body is, for example, a nonwoven fabric.

The fiber includes nanofibers having a fiber diameter of less than 1 μm. The fiber diameter of the nanofiber is a value representative of the thickness of the nanofiber, and may be an average value, a median value, or a mode value, for example. Good. When the fiber diameter of the nanofiber is 1 μm or more, the fiber does not correspond to the nanofiber, and the sound absorption effect described later may be insufficient. The fiber diameter is preferably 0.20 to 0.95 μm, more preferably 0.20 to 0.70 μm, from the viewpoint of sound absorption effect and prevention of collapse of the non-planted structure.

The fiber diameter can be obtained by observing an enlarged image of the fiber body. For example, for the fiber diameter, a lump containing the fiber body of about 3 mm square is stuck on a carbon tape, Au is evaporated on the fiber body for about 2 minutes, and a scanning electron microscope VE-7800 (manufactured by Keyence Corporation) is used. Using the above, the fiber body is observed at a magnification of 3000 times, and the fiber diameters of arbitrary 10 nanofibers can be measured and obtained as an average value thereof.

The nanofiber is made of resin. The resin can be appropriately selected from resins used as raw materials for chemical fibers. The resin may be one kind or more, and examples thereof include general-purpose plastic, engineering plastic, and super engineering plastic. Examples of the general-purpose plastic include polypropylene (PP), polyethylene (PE), polyurethane (PU), polylactic acid (PLA), and acrylic resin (for example, PMMA). Examples of the engineering plastic include polyethylene terephthalate (PET), nylon 6 (N6), nylon 6,6 (N66), and nylon 12 (N12). Examples of the super engineering plastic include polyphenylene sulfide (PPS) and liquid crystal polymer (LCP). Especially, it is preferable that the said resin is a polypropylene from the viewpoint of making the sound absorption effect and the versatility with respect to the sound of the low frequency range represented by the sound absorption rate of 1 kHz compatible.

The thickness of the fibrous body is 10 mm or more. The thickness of the fibrous body is measured at an appropriate portion according to the shape of the fibrous body. For example, if the shape of the fibrous body is a sheet, it is the average thickness of the flat portion of the fibrous body. Moreover, when the shape of the said fiber body contains an unevenness | corrugation, it is the average thickness in the deepest recessed part (part where the thickness of a fiber body becomes the minimum), or the area occupation rate in the plane direction of the said recessed part is low In the case of (for example, less than 50%), it is a value obtained by leveling the height difference of the surface shape of the fibrous body.

Moreover, in the nonwoven fabric structure including a plurality of stacked fiber bodies, which will be described later, the thickness of the fiber body is the sum of the thicknesses of the fiber bodies in the stacking direction. When the fiber body is supported by one or more supports described later, the thickness of the fiber body may be the thickness of the fiber body on the support, and the thickness of the support body is that of the fiber body. When the thickness is sufficiently small with respect to the thickness (for example, the thickness of the support is 200 μm or less), the thickness of the support may be included.

If the thickness is less than 10 mm, the absorption rate of sound waves having a frequency of 1 kHz or less may be insufficient. The thickness can be obtained, for example, by measuring the thickness at any of a plurality of locations in the fibrous body and averaging them. The said thickness can be suitably determined according to the use of the said nonwoven fabric structure. There is no upper limit on the sound absorption effect depending on the thickness, but the shape and size of the nonwoven fabric structure may be limited in the space in which the sound absorbing material is installed depending on, for example, in-vehicle use. In addition, it may be limited by the usage environment of the nonwoven fabric structure. Therefore, the upper limit value of the thickness of the nonwoven fabric structure is usually determined as appropriate according to the application.

For example, if it is a sound absorbing material that can be used for in-vehicle use, the thickness of the fibrous body is preferably 20 mm or more from the viewpoint of exhibiting a sufficient sound absorbing effect, and the sound absorbing material can be arranged according to the application. From the viewpoint of space saving, it is preferably 36 mm or less, and more preferably 30 mm or less. For example, from the above viewpoint, the thickness of the fibrous body may be 20 mm.

The sound absorbing effect of the sound absorbing material can be defined by the sound absorption rate of 1 kHz sound and the sound absorption rate of 6 kHz sound.

From the viewpoint of sufficiently absorbing a sound in a lower frequency range as compared with the conventional sound absorbing material, the sound absorption rate of the 1 kHz sound is preferably 0.59 or more, and more preferably 0.68 or more. 0.72 or more is more preferable, and 0.82 or more is even more preferable. Further, from the viewpoint of the balance between the sound absorbing effect and the space saving, the sound absorption rate of the 1 kHz sound may be 0.84 or less, for example, 0.82. The sound absorption coefficient of 1 kHz sound can be increased, for example, by increasing the mass ratio of nanofibers in the fibrous body.

From the viewpoint of expressing sound absorption characteristics equivalent to or higher than those of conventional sound absorbing materials, the sound absorption rate of 6 kHz sound may be, for example, 0.80, preferably 0.80 or more, and preferably 0.84 or more. More preferably, it is more preferably 0.88 or more. Further, from the viewpoint of the balance between the sound absorption effect and the space saving, the sound absorption rate of the 6 kHz sound may be 0.96 or less, or 0.93 or less. A sound absorption coefficient of 6 kHz sound can be achieved, for example, by a sufficient thickness and fiber density of the fiber body.

The fiber density of the fiber body is 10 kg / m ³ or more and less than 50 kg / m ³ . If the fiber density is less than 10 kg / m ³ , the sound absorbing effect described below may be insufficient for both sound having a frequency of 1 kHz or less and sound having a higher frequency. When the fiber density is 50 kg / m ³ or more, the sound absorption effect of a sound in a high frequency region having a frequency of 4 kHz or more (for example, 6 kHz), or a sound in the vicinity of a frequency of 1 kHz may be insufficient.

Further, the fiber density is 10 to 25 kg / m ³ , in addition to the sound absorption effect for sound with a frequency of 1 kHz or less, and for sound in a high frequency range (for example, 2 to 6 kHz) having a higher frequency. It is preferable from the viewpoint of producing and enhancing a sound absorbing effect.

The fiber density is obtained by dividing the basis weight of the fiber body by the thickness. The basis weight is the mass of fibers per unit area in the fiber body. The basis weight is determined, for example, by calculating the mass per unit area from the mass of the fibrous body. The fiber density can be adjusted by one or both of the basis weight and the thickness.

The fiber body may be composed of only nanofibers or may further include microfibers in addition to nanofibers. The microfiber is, for example, a fiber having a fiber diameter of 2 to 50 μm. It is preferable that the fibrous body contains the microfiber from the viewpoint of further increasing the strength of the fibrous body and maintaining the shape of the fibrous body (suppressing deformation due to compression of the fibrous body).

The type of microfiber may be one or more. If the content of the microfiber in the fiber body is too large, the sound absorption effect by the fiber body may be insufficient. If the content is too small, the effect of improving the strength of the fiber body due to the mixing of the microfiber is obtained. It may be insufficient. From the viewpoint of the sound absorption effect and the strength improvement effect, the content ratio of the nanofiber in the fiber body is 0.5 or more in terms of mass ratio.

The above-mentioned content ratio can be appropriately determined within a range that can sufficiently absorb a sound in a lower frequency range than a conventional sound absorbing material represented by a sound of 1 kHz. For example, from the above viewpoint, the content ratio may be 0.5, 0.75, or 1.0.

When microfibers are included, it is preferable that nanofibers are sufficiently present in the thickness direction of the fibrous body from the viewpoint of expressing the sound absorption effect of the nanofibers.

The fiber diameter and the content of the microfiber can be obtained by observing an enlarged image of the fiber body. For example, the fiber diameter of the microfiber can be obtained in the same manner as the fiber diameter of the nanofiber described above except that the magnification in the enlarged image is appropriately adjusted (for example, 100 times). In the measurement of the fiber diameter of the microfiber, it is not necessary to deposit gold if the microfiber can be sufficiently confirmed in an enlarged image of an optical microscope other than the scanning electron microscope.

Further, the content of the microfiber can be obtained from the ratio of the occupied area of the nanofiber and the occupied area of the microfiber in the enlarged image. Alternatively, the content of the microfiber can be determined from the difference in mass of the sample before and after the removal by separating and removing the microfiber or nanofiber from the sample of the fibrous body having a known mass.

The distribution width of the fiber diameter distribution of the nanofiber is narrower than the distribution width of the fiber diameter distribution of the microfiber, and appropriately controls the sound absorption effect by the nanofiber and the strength improvement effect by the microfiber. It is preferable from the viewpoint. The fiber diameter distribution of the nanofiber can be appropriately determined within a range where the fiber diameter of the nanofiber is less than 1 μm.

The non-woven fabric structure may be configured by directly arranging the fibrous body at an intended site, but may further include a support for supporting the fibrous body. It is preferable that the nonwoven fabric structure has the support from the viewpoint of maintaining the desired shape of the fibrous body. The support is a sheet-like member, for example. The material of the support can be appropriately selected within the range where the effects of the present embodiment are exhibited. Examples of the support include a nonwoven fabric, a woven fabric, a film, paper, and a foam layer. It is preferable that the support is sufficiently thin as compared with the fiber body and further excellent in air permeability or liquid permeability from the viewpoint of sufficiently expressing the intended function of the fiber body. The thickness of the support is, for example, 20 to 500 μm.

The support may be one or more. For example, the fiber body may be supported by the support body on one side, or may be supported by being sandwiched between two support bodies. Moreover, the said nonwoven fabric structure may have the said 2 or more said fiber body, and may have the said support body at least between the said fiber bodies. For example, two fiber bodies may be supported on each of both surfaces of one support. The structure in which the support is arranged between the fibrous bodies greatly increases the strength against deformation (for example, collapse) of the fibrous body due to the flexibility of the nanofiber, and deformation or destruction (for example, tearing) in the planar direction. It is effective from the viewpoint of improving it.

The fiber body can be manufactured using a known manufacturing method of nanofibers as described in Patent Document 2, for example. For example, the fibrous body can be manufactured by a melt spinning apparatus using high-speed air. The melt spinning apparatus includes, for example, a melt extruder that melts and transports a thermoplastic resin, a spinning nozzle that discharges the transported molten resin into a fiber shape, and an air nozzle that blows high-temperature heated air near the spinning nozzle. . The fiber body can be produced by using the melt spinning apparatus to quickly stretch the thermoplastic resin with the high-speed air stream. Here, the melt spinning device may further include a voltage applying device that applies a high voltage to the molten resin discharged from the spinning nozzle, if necessary. By having the voltage applying device, the melt spinning device can further adjust the fiber diameter in the fiber body.

In addition, the fiber body further including the microfibers may be obtained by simultaneously spinning a plurality of the melt spinning apparatuses that utilize high-speed air in the longitudinal direction, the lateral direction, or in both directions, and spinning the nanofibers. Can be manufactured by collecting and combining fibers of different resins and fiber diameters.

This method spins nanofiber and microfiber simultaneously. For this reason, it is possible to produce the fiber body in which the nanofibers and the microfibers are substantially uniform, and the nanofibers are sufficiently present and intertwined with the microfibers (see FIGS. 4A and 4B). Said method is preferable from a viewpoint of making a nanofiber fully exist in the thickness direction of a fibrous body.

Further, the fiber body supported by the support body generates, for example, an air flow from the air nozzle toward the surface of the support body, and is provided from one or both of the first spinning nozzle and the second spinning nozzle. It is possible to manufacture by discharging the material of the period and collecting the produced fiber on the surface of the support.

Furthermore, the nonwoven fabric structure composed of a plurality of stacked fiber bodies supported by the support body includes a plurality of the support bodies, or the fibers of the fiber body supported on the support body. It is possible to manufacture by combining the bodies or the support and the fibrous body and bonding, welding, or fixing a part thereof as necessary.

In addition to the melt spinning apparatus utilizing the high-speed air, a known method such as a melt blown method or an electrospinning method is not desirable from the viewpoint of stable productivity, but is used for manufacturing the fibrous body. It is possible. Further, the nanofiber and the microfiber may be manufactured by the same method or may be manufactured by different methods.

A specific example of the nonwoven fabric structure is illustrated. FIG. 1A is a diagram schematically illustrating a first aspect of the nonwoven fabric structure, FIG. 1B is a diagram schematically illustrating a second aspect of the nonwoven fabric structure, and FIG. 1C is a diagram illustrating the nonwoven fabric. FIG. 1D is a diagram schematically showing a fourth aspect of the nonwoven fabric structure, and FIG. 1E is a fifth diagram of the nonwoven fabric structure. It is a figure which shows an aspect typically.

The non-woven fabric structure 10A is composed of only the fiber body 1 as shown in FIG. 1A. The fiber body 1 is configured to satisfy the above-described thickness and density with only nanofibers or with nanofibers and microfibers.

The nonwoven fabric structure 10B is comprised from the fiber body 1 and the support body 2, as FIG. 1B shows. The support 2 is, for example, a resin nonwoven fabric sheet. The fiber body 1 is supported on one surface of the support 2. The nonwoven fabric structure 1B is produced, for example, by forming the fiber body 1 on one surface of the support 2.

As shown in FIG. 1C, the nonwoven fabric structure 10C is composed of a fiber body 1 and two supports 2 that sandwich the fiber body 1 from both sides in the thickness direction. The nonwoven fabric structure 10C is produced, for example, by combining the fiber bodies 1 of the two nonwoven fabric structures 1B.

As shown in FIG. 1D, the nonwoven fabric structure 10 </ b> D is configured such that the fiber body 1 is supported on each of both surfaces of a single support body 2. The nonwoven fabric structure 1D is produced, for example, by forming the fiber body 1 simultaneously on both surfaces of a single support 2 or sequentially on one surface of the support 2.

The nonwoven fabric structure 1E is composed of a plurality of fibrous bodies 1 and a plurality of supports 2 as shown in FIG. 1E. The support body 2 is arrange | positioned at the both sides in the thickness direction of each fiber body 1. FIG. The nonwoven fabric structure 1E is produced, for example, by appropriately stacking one or more of the nonwoven fabric structures 1B, 1C, 1D.

The non-woven fabric structure is excellent in both sound absorption performance with a frequency higher than 1 kHz and sound absorption performance with a frequency of 1 kHz or less. The reason is considered as follows.

The above-mentioned fibrous body is composed of fibers sufficiently containing nanofibers, and has a sufficient thickness and an appropriate fiber density. Very minute voids are formed inside the fibrous body. Sound that is vibration (sound waves) of air passes through the fiber body.

The nanofibers are thin and rich in flexibility. Therefore, the nanofibers resonate due to the vibration of the air. For this reason, the nanofiber vibrates and heat is generated by friction between the nanofibers. Thus, the sound energy that vibrates the nanofibers is converted into thermal energy by vibrating the nanofibers through the fiber body.

In the above-mentioned fibrous body having a thickness of 10 mm or more, a sound absorption effect of sound in a low frequency range of 1 kHz or less is more likely to occur compared to a conventional fibrous body. This is not only because the nanofibers are sufficiently flexible and exist with sufficient fiber density, so that not only the higher frequency, more vibration energy, but also the lower frequency, lower vibration energy. This is probably because it can be converted into thermal energy.

In addition, when the fiber density of the said fiber body is lower than the above-mentioned range, resonance of a nanofiber does not fully generate | occur | produce and the sound absorption effect of the sound of the low frequency range below 1 kHz may become inadequate. Further, if the fiber density of the fibrous body is higher than the above range, sound reflection at the surface of the fibrous body is likely to occur, and the sound absorption effect of the sound in the low frequency range in the fibrous body becomes insufficient. There is. On the other hand, when the fiber density of the fibrous body is 10 to 25 kg / m ³ , the sound absorption effect of the low frequency range sound can be sufficiently obtained, and the sound absorption effect of the medium frequency range sound can be sufficiently obtained. May be.

As is clear from the above description, the sound absorbing material includes a nonwoven fabric structure having a fiber body in which fibers are entangled, and the fiber includes a nanofiber made of polypropylene having a fiber diameter of less than 1 μm, The thickness of the fiber body is 20 mm or more and 36 mm or less, the fiber density of the fiber body is 10 kg / m ³ or more and less than 50 kg / m ³ , and the content ratio of the nanofiber in the fiber body is 0.5 by mass ratio. Since the sound absorption coefficient of 1 kHz sound is 0.59 or more and 0.84 or less and the sound absorption coefficient of 6 kHz sound is 0.80 or more and 0.96 or less, the sound in the low frequency range is excellent. Appears sound absorbing properties.

Moreover, it is much more effective that the said nonwoven fabric structure further has the support body which supports the said fiber body from a viewpoint of maintaining the original shape of the said fiber body, and the viewpoint of raising the intensity | strength of a nonwoven fabric structure. . In addition, from the above viewpoint, the nonwoven fabric structure may be supported by the fiber body supported by the support on one side or sandwiched between the two supports, or the nonwoven fabric. The structure may have two or more of the fiber bodies, and may have the support body at least between the fiber bodies.

Further, the support is at least one selected from the group consisting of a nonwoven fabric, a woven fabric, a film, paper, and a foam layer, and is more effective from the viewpoint of easy availability and enhancing the productivity of the nonwoven fabric structure. It is.

In addition, it is more effective from the viewpoint of maintaining the desired shape of the fibrous body and increasing the strength of the fibrous body that the fibrous body further includes microfibers having a fiber diameter of 2 to 50 μm. It is.

In addition, the distribution width of the fiber diameter distribution of the nanofiber is narrower than the distribution width of the fiber diameter distribution of the microfiber, from the viewpoint of designing the sound absorption effect of the low-frequency sound and the strength improvement effect. More effective.

A structure having continuous fine voids is formed in the fibrous body, and a member having such a structure is usually used for the support. Therefore, the nonwoven fabric structure generally has the above-described unique sound absorption characteristics and also has air permeability or liquid permeability. Therefore, the said nonwoven fabric structure can be employ | adopted for both the use which requires said sound-absorbing characteristic, and the use which requires both the said sound-absorbing characteristic and another function other than that, for example. Moreover, the said nonwoven fabric structure can also be employ | adopted for the use only of said other function. From such a viewpoint, the nonwoven fabric structure is suitably used as a constituent member of nonwoven fabric products such as a sound absorbing material, a sound insulating material, a filtering material, a heat insulating material, an insulating separator, an oil adsorbing material, a surface cleaning cloth, and a medical covering material. Used.

<Example 1>
First, air of high speed and high temperature (for example, 200 m / sec, 300 ° C.) is ejected in one direction from the air nozzle, and a nonwoven fabric made of polypropylene is installed as a support downstream of the high speed and high temperature airflow from the air nozzle. The nonwoven fabric is a nonwoven fabric produced by a spunlace method, and its basis weight is 20 g / m ³ and its thickness is 140 μm.

Next, polypropylene (PP, “Prime Polypro J106G” manufactured by Prime Polymer Co., Ltd.) is passed through a spinning nozzle adjusted to 300 ° C. and sufficiently melted, and then the melted PP is passed from the spinning nozzle to the high-speed high-temperature air flow. The nanofibers having a fiber diameter of 0.50 μm and a fiber length of 100 cm are produced and collected on the surface of the nonwoven fabric on the downstream side. Thus, a fiber body of nanofibers having a fiber diameter of 0.50 μm (500 nm), a basis weight of 350 g / m ² , and a fiber density of 17.5 kg / m ³ is supported on the surface of the nonwoven fabric, as shown in FIG. 1B. A sheet-like nonwoven fabric structure 1 was prepared.

Moreover, the thickness of the nonwoven fabric structure 1 is 20 mm. The thickness of the nonwoven fabric structure 1 is the average value of the total thickness of the nonwoven fabric and the fibrous body, and the average value of the total thickness measured at any five locations in the plane direction of the nonwoven fabric structure 1. It is.

As described above, the fiber diameter was measured by attaching a fiber body 1 sample of about 3 mm square on a carbon tape, then depositing Au on the sample for about 2 minutes, and then scanning electron microscope VE-7800 (Keyence Corporation). The above-mentioned sample was observed at a magnification of 3000 times using a manufactured product, the fiber diameters of arbitrary 10 nanofibers in the obtained enlarged image were measured, and the average value thereof was obtained.

The weight per unit area was calculated from the fibrous body cut into a square having a planar shape of 10 cm × 10 cm, the weight was measured, and the area in the planar direction (100 cm ² ). Moreover, the said fiber density was calculated | required by the product of the said fabric weight and the thickness of the following nonwoven fabric structure.

In addition, by observing the fibrous body with a scanning electron microscope (SEM), as shown in FIGS. 3A and 3B, the nanofiber is uniform and uniform in both the planar direction and the thickness direction of the fibrous body. It is confirmed that a dense fiber body is formed.

<Example 2, Reference Example 4 and Comparative Examples 3, 5 to 7>
Other than adjusting the temperature of the spinning nozzle, adjusting the discharge amount of PP, adjusting the flow rate of the high-speed and high-temperature air flow, adjusting the collection time of the fiber to be generated, and compressing the fiber body in the thickness direction as necessary Produced nonwoven fabric structures 2 to 7 in the same manner as nonwoven fabric structure 1, respectively.

The fiber diameter of the fibrous body in the nonwoven fabric structure 2 is 0.35 μm, the basis weight is 390 g / m ² , and the fiber density is 17.7 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 2 is 22 mm. The fiber diameter of the fibrous body in the nonwoven fabric structure 3 is 0.50 μm, the basis weight is 350 g / m ² , and the fiber density is 35.0 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 3 is 10 mm. The fiber diameter of the fibrous body in the nonwoven fabric structure 4 is 0.50 μm, the basis weight is 756 g / m ² , and the fiber density is 47.3 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 4 is 16 mm. The fiber diameter of the fibrous body in the nonwoven fabric structure 5 is 0.50 μm, the basis weight is 500 g / m ² , and the fiber density is 27.8 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 5 is 18 mm. The fiber diameter of the fibrous body in the nonwoven fabric structure 6 is 0.50 μm, the basis weight is 453 g / m ² , and the fiber density is 25.2 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 6 is 18 mm. Fiber diameter of the fibrous body in a nonwoven structure 7 is 0.35 .mu.m, basis weight is 190 g / ^{m 2,} the fiber density is 19.0 kg / ^{m 3.} Moreover, the thickness of the nonwoven fabric structure 7 is 10 mm.

<Reference Examples 8, 9 and Example 10>
The fiber diameter is 0.50 μm (500 nm) on the surface of the nonwoven fabric in the same manner as the nonwoven fabric structure 1 except that the temperature of the spinning nozzle, the discharge amount of PP, and the flow rate of the high-speed high-temperature airflow are adjusted as necessary. A nonwoven fabric structure unit 8 as shown in FIG. 1B in which a fiber body having a basis weight of 187 g / m ² and a fiber density of 46.8 kg / m ³ was supported was produced. The thickness of the nonwoven fabric structure unit 8 is 4 mm.

A nonwoven fabric structure 8 having three layers of the fibrous body as shown in FIG. 1E is obtained by stacking three nonwoven fabric structure units 8 and further stacking the nonwoven fabric on the uppermost portion and fixing them appropriately. Produced. The thickness of the nonwoven fabric structure 8 is 12 mm.

Furthermore, a nonwoven fabric structure 9 was produced in the same manner as the nonwoven fabric structure 8 except that four nonwoven fabric structure units 8 were stacked. Moreover, the nonwoven fabric structure 10 was produced in the same manner as the nonwoven fabric structure 8 except that five nonwoven fabric structure units 8 were stacked. The thickness of the nonwoven fabric structure 9 is 16 mm, and the thickness of the nonwoven fabric structure 10 is 20 mm.

<Example 11 and Reference Example 12>
A melted polyethylene terephthalate (PET, “TRN-8550T” manufactured by Teijin Ltd.) from the second spinning nozzle adjusted to 280 ° C. arranged toward the high-speed and high-temperature air stream is simultaneously added to the PP. A nonwoven fabric structure 11 was produced in the same manner as the nonwoven fabric structure 1 except that it was discharged into a high-speed high-temperature air stream. The fibrous body of the nonwoven fabric structure 11 is a mixture of PP nanofibers and PET microfibers in a mass ratio of 1: 1.

The fiber diameter of the nanofiber in the fiber body of the nonwoven fabric structure 11 is 0.50 μm, and the fiber diameter of the microfiber is 11 μm. The basis weight of the fibrous body is 1140 g / m ² and the fiber density is 49.6 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 11 is 23 mm.

The fiber diameter of the microfiber was determined by measuring in the same manner as the fiber diameter of the nanofiber, except that the magnification in the enlarged image was 100 times.

Further, by observing the fibrous body with an SEM, as shown in FIGS. 4A and 4B, the nanofibers and the microfibers are uniformly mixed in both the planar direction and the thickness direction of the fibrous body. In addition, it is confirmed that a fiber body in which the nanofibers are sufficiently present between the microfibers is configured.

Also, adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air current, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body The nonwoven fabric structure 12 was produced in the same manner as the nonwoven fabric structure 11 except that the above steps were performed as necessary. The basis weight of the fibrous body of the nonwoven fabric structure 12 is 760 g / m ² , and the fiber density is 47.5 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 12 is 16 mm.

<Reference Examples 13, 15, and 17 and Examples 14 and 16>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body A nonwoven fabric structure 13 was produced in the same manner as the nonwoven fabric structure 11 except that it was performed as necessary. The fiber diameter of the nanofiber in the fiber body of the nonwoven fabric structure 13 is 0.50 μm, and the fiber diameter of the microfiber is 20 μm. The basis weight of the fibrous body is 331 g / m ² and the fiber density is 18.4 kg / m ³ . Furthermore, the thickness of the nonwoven fabric structure 13 is 18 mm. In the fibrous bodies of the nonwoven fabric structures 13 to 17, PP nanofibers and PET microfibers are mixed at a mass ratio of 1: 1.

Also, adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber, and compression in the thickness direction of the fiber body The nonwoven fabric structures 14 to 17 were produced in the same manner as the nonwoven fabric structure 13 except that the above steps were performed as necessary. The fiber diameters of the nanofibers in the nonwoven fabric structures 14 to 17 are all 0.50 μm, and the fiber diameters of the microfibers are all 20 μm.

The fabric weight of the nonwoven fabric structure 14 is 691 g / m ² , and the fiber density is 19.2 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 14 is 36 mm. The basis weight of the fibrous body of the nonwoven fabric structure 15 is 691 g / m ² , and the fiber density is 34.6 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 15 is 20 mm. The basis weight of the fibrous body of the nonwoven fabric structure 16 is 509 g / m ² , and the fiber density is 17.0 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 16 is 30 mm. The basis weight of the fibrous body of the nonwoven fabric structure 17 is 509 g / m ² , and the fiber density is 36.4 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure 17 is 14 mm.

<Examples 18 to 20>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body A nonwoven fabric structure 18 was produced in the same manner as the nonwoven fabric structure 11 except that it was performed as necessary. The fiber diameter of the nanofiber in the fiber body of the nonwoven fabric structure 18 is 0.50 μm, and the fiber diameter of the microfiber is 21 μm. The basis weight of the fibrous body is 480 g / m ² and the fiber density is 16.0 kg / m ³ . Furthermore, the thickness of the nonwoven fabric structure 18 is 30 mm. In the fibrous body of the nonwoven fabric structures 18 to 20, nanofibers made of PP and microfibers made of PET are mixed at a mass ratio of 3: 1.

Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body Nonwoven fabric structures 19 and 20 were respectively produced in the same manner as the nonwoven fabric structure 18 except that it was performed as necessary. In both of the nonwoven fabric structures 19 and 20, the fiber diameter of the nanofiber is 0.50 μm, and the fiber diameter of the microfiber is 21 μm. Moreover, the thickness of the nonwoven fabric structure 19 is 27 mm, and the fiber density of the fibrous body is 17.8 kg / m ³ . Furthermore, the thickness of the nonwoven fabric structure 20 is 20 mm, and the fiber density of the fibrous body is 24.0 kg / m ³ .

<Reference Example 21 and Examples 22 and 23>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body A nonwoven fabric structure unit 21 was produced in the same manner as the nonwoven fabric structure 11 except that it was performed as necessary.

The fiber body of the nonwoven fabric structure unit 21 is a mixture of PP nanofibers and PET microfibers in a mass ratio of 1: 1, and the fiber diameter of the nanofibers in the fiber body is 0.50 μm, The fiber diameter of the microfiber is 11 μm. The basis weight of the fibrous body is 190 g / m ² and the fiber density is 47.5 kg / m ³ . Furthermore, the thickness of the nonwoven fabric structure unit 21 is 4 mm.

The nonwoven fabric structure 21 having three layers of the fibrous body was produced by stacking three nonwoven fabric structure units 21 and further stacking the nonwoven fabric on the uppermost portion and fixing them appropriately. The thickness of the nonwoven fabric structure 21 is 12 mm.

Nonwoven fabric structures 22 and 23 were produced in the same manner as the nonwoven fabric structure 21 except that 5 and 6 nonwoven fabric structure units 21 were stacked, respectively. The thickness of the nonwoven fabric structure 22 is 20 mm, and the thickness of the nonwoven fabric structure 23 is 24 mm.

<Comparative Example 1>
“Thin Sulate TAI3047” (“Thin Sulate” is a registered trademark of the company) manufactured by 3M Japan Ltd. was prepared, and this was designated as a nonwoven fabric structure C1. The nonwoven fabric structure C1 has a fiber body in which polypropylene microfibers 1 and polyester microfibers 2 are mixed. The fiber diameter of the microfiber 1 is about 2 μm, and the fiber diameter of the microfiber 2 is about 25 μm. Further, the ratio (MF1: MF2) of the mass (MF1) of the microfiber 1 and the mass (MF2) of the microfiber 2 is about 65:35. Moreover, the fabric weight of the nonwoven fabric structure C1 in the fiber body is 315 g / m ² , and the fiber density is 17.5 kg / m ³ . Moreover, the thickness of the nonwoven fabric structure C1 is 18 mm.

<Comparative Examples 2 and 3>
Except for adjusting the temperature of the spinning nozzle, adjusting the discharge rate of PP, adjusting the flow rate of the high-speed and high-temperature air flow, adjusting the collection time of the produced fiber, and compressing the fiber body in the thickness direction, as necessary In the same manner as the nonwoven fabric structure 1, nonwoven fabric structures C2 and C3 similar to the nonwoven fabric structure 1 were produced except that the fiber density and thickness were different.

The fiber density of the fibrous body of the nonwoven fabric structure C2 is 50.0 kg / m ³ , and the thickness of the nonwoven fabric structure C2 is 7 mm. Moreover, the fiber density of the fibrous body of the nonwoven fabric structure C3 is 87.5 kg / m ³ , and the thickness of the nonwoven fabric structure C3 is 4 mm.

<Comparative Examples 4 to 6>
Except for adjusting the temperature of the spinning nozzle, adjusting the discharge rate of PP, adjusting the flow rate of the high-speed and high-temperature air flow, adjusting the collection time of the produced fiber, and compressing the fiber body in the thickness direction, as necessary In the same manner as each of the nonwoven fabric structures 4 to 6, nonwoven fabric structures C4 to C6 that were the same as the nonwoven fabric structures 4 to 6 except that the fiber density and thickness were different were produced.

The fiber density of the fibrous body of the nonwoven fabric structure C4 is 75.6 kg / m ³ , and the thickness of the nonwoven fabric structure C4 is 10 mm. The fiber density of the fibrous body of the nonwoven fabric structure C5 is 55.6 kg / m ³ , and the thickness of the nonwoven fabric structure C5 is 9 mm. The fiber density of the fibrous body of the nonwoven fabric structure C6 is 50.3 kg / m ³ , and the thickness of the nonwoven fabric structure C6 is 9 mm.

<Comparative Examples 7 and 8>
The nonwoven fabric structure unit 8 was designated as a nonwoven fabric structure C7. Moreover, the nonwoven fabric structure C8 was produced in the same manner as the nonwoven fabric structure 8 except that the number of the nonwoven fabric structure units stacked was two. The thickness of the nonwoven fabric structure C8 is 8 mm.

<Comparative Examples 9 and 10>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body Non-woven fabric structures C9 and C10 were respectively produced in the same manner as the non-woven fabric structure 11 except for the case where necessary.

The thickness of the nonwoven fabric structure C9 is 7 mm, the basis weight of the fibrous body is 380 g / m ² , and the fiber density is 54.3 kg / m ³ . The thickness of the nonwoven fabric structure C10 is 4 mm, the basis weight of the fibrous body is 190 g / m ² , and the fiber density is 47.5 kg / m ³ . The basis weight and fiber density of the nonwoven fabric structure C10 are equivalent to those of the nonwoven fabric structure unit 21.

<Comparative Example 11>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body A nonwoven fabric structure C11 was produced in the same manner as the nonwoven fabric structure 13 except that it was carried out as necessary. The thickness of the nonwoven fabric structure C11 is 7 mm, the basis weight of the fibrous body is 331 g / m ² , and the fiber density is 47.3 kg / m ³ .

<Comparative Example 12>
Adjustment of spinning nozzle temperature, adjustment of PP discharge amount, adjustment of PET discharge amount, adjustment of flow rate of high-speed and high-temperature air flow, adjustment of collection time of generated fiber and compression in the thickness direction of the fiber body A nonwoven fabric structure C12 was produced in the same manner as the nonwoven fabric structure 18 except that it was performed as necessary. The thickness of the nonwoven fabric structure C12 is 9 mm, the basis weight of the fibrous body is 480 g / m ² , and the fiber density is 53.3 kg / m ³ .

For each of the nonwoven fabric structures 1 to 23 and C1 to C12, the sound absorption coefficient (perpendicular incident absorption coefficient) of sound having a frequency of 200 Hz to 6 kHz from the direction perpendicular to the plane direction of the nonwoven structure is measured with an acoustic impedance tube. It was measured using the vertical sound absorption system used (“DS-200” manufactured by Ono Sokki Co., Ltd.). The structures and physical properties of the nonwoven fabric structures 1 to 23 and C1 to C12 and the measurement results of the normal incidence sound absorption coefficient are shown in Tables 1 to 3, respectively. FIG. 2 shows the normal incidence sound absorption coefficient of the

nonwoven fabric structures

1 and 2 and the nonwoven fabric structure C1. In the figure, the solid line indicates the normal incident sound absorption coefficient of the nonwoven fabric structure 1, the one-dot chain line indicates the non-woven structure 2, and the broken line indicates the normal incident sound absorption coefficient of the nonwoven structure C1, respectively.

As is apparent from Table 3 and FIG. 2, the nonwoven fabric structure C1 having a fibrous body composed of microfibers has an insufficient sound absorption coefficient of about 0.1 in a frequency range of about 1 kHz or less, from about 1 kHz to about 1 kHz. The sound absorption rate gradually increases in the frequency range up to 5 kHz, and a sufficient sound absorption rate of 0.9 or more is shown at a frequency of about 5 kHz or more.

As is apparent from Tables 1 and 2 and FIG. 2, in the fiber body using nanofibers, the nonwoven fabric structures 1 to 6 having a thickness of 10 mm or more and a fiber density of 10 kg / m ³ or more and less than 50 kg / m ^3. Each of the nonwoven fabric structures 8 to 23 has a high sound absorption coefficient higher than that of the nonwoven fabric structure C1 in a frequency range up to about 3 kHz, specifically 0.2 or more at 1 kHz and 0.2 at 2 kHz. A sound absorption coefficient of 0.7 or more is exhibited even at 5 or more and 3 kHz. And these nonwoven fabric structures have a sufficiently high sound absorption coefficient even at a frequency of about 4 kHz or higher.

Thus, it can be seen that the above-described nonwoven fabric structure is superior in sound absorption of sound in a lower frequency range than the nonwoven fabric structure using microfibers. This is presumably because, as described above, the efficiency of conversion of sound into thermal energy due to viscosity in the fiber body of the nanofiber is increased, and the sound absorption effect due to resonance of the fiber body itself is likely to occur.

As shown in FIG. 2, the effect is particularly remarkable in the

nonwoven fabric structures

1 and 2 having a thickness of 16 mm or more and a high ratio of nanofibers, and is 0.8 or more at 1 kHz and 0.7 at 2 kHz. As described above, a sound absorption coefficient of 0.7 or more is shown even at 3 kHz.

Further, according to the comparison between the nonwoven fabric structure 7 and the nonwoven fabric structure C1, it can be said that the sound absorption characteristics of the two are almost equal. However, the thickness of the nonwoven fabric structure 7 is 10 μm, and the basis weight is 190 g / m ² , which is a sufficiently small value compared to those of the nonwoven fabric structure C1. Thus, even when the basis weight is 200 g / cm ² or less and the thickness is 15 mm or less, the sound absorbing effect equivalent to that of the conventional microfiber nonwoven fabric structure is provided. Therefore, by constituting the fibrous body with nanofibers, the same sound absorbing effect can be obtained with a lighter and thinner nonwoven fabric structure as compared with a nonwoven fabric structure including a fibrous body composed of conventional microfibers.

Further, according to the comparison between the nonwoven fabric structure 1 and the nonwoven fabric structure 2, it can be seen that the smaller fiber diameter of the fiber body is effective from the viewpoint of further improving the sound absorption characteristics in the frequency range of 5 kHz or less. . This is because the above-mentioned fibrous body composed of more flexible nanofibers is less rigid, and the nanofibers are more likely to resonate. As a result, the sound absorption effect in the low frequency range is increased. ,it is conceivable that.

Further, according to the comparison between the nonwoven fabric structures 8 to 10 and the nonwoven fabric structure C8, the sound absorption coefficient is reduced by stacking the nonwoven structure units 8 having a low sound absorption coefficient in the vicinity of 1 kHz due to insufficient thickness. It can be seen that it can be increased.

Further, in the nonwoven fabric structures 8 to 10, since the support layer is disposed between the fiber layers, the deformation (for example, collapse) of the nonwoven fabric structure in the thickness direction by the nanofibers and the planar direction The strength against deformation (for example, tearing) or the like is greatly improved as compared with the nonwoven fabric structure 1 or the like that does not have such a support between layers.

As a result, the fiber density of the nonwoven fabric structure becomes more stable over time due to the suppression of crushing. Even if the fiber density in the fiber body is high, it is expected that the loss of the fiber body when a fluid such as gas or liquid passes through the fiber body is suppressed. In addition, it is expected that the sound absorption effect due to resonance in each layer of the fiber body and the resonance effect due to reflection absorption in a part of the wavelength region between the fiber body layers are also generated. Therefore, it is expected that the degree of freedom in designing the sound absorption characteristics in the nonwoven fabric structure can be increased so that the optimum sound absorption characteristics are expressed with a wider fiber density.

Further, according to the nonwoven fabric structures 11 to 23, even if the fiber body is a composite fiber in which at least microfibers and nanofibers are mixed, the mass ratio of the nanofibers is within the range of 0.5 or more. It can be seen that the same effect as the above sound absorption effect by the fiber body can be obtained. In the fiber body of the composite fiber, in addition to the above-described effects, the presence of the microfiber is expected to further improve the strength of the fiber body itself and further suppress deformation of the fiber body itself.

On the other hand, the nonwoven fabric structures C7, C8, C10, and C11 all had insufficient sound absorption characteristics in a frequency range of at least 1 kHz or less. This is presumably because the density of the fibrous body is in a predetermined range, but the thickness of the fibrous body is less than 10 mm, so that the sound absorption effect due to the resonance described above was not sufficiently exhibited.

Further, in the nonwoven fabric structures C2 to C6 and the nonwoven fabric structures C9 and C12, the sound absorption coefficient was 0.7 or less in a frequency range of at least 4 kHz, and the sound absorption characteristics were insufficient. Furthermore, in the nonwoven fabric structures C3, C9, and C12, the sound absorption coefficient is 0.15 or less near 1 kHz, and the sound absorption characteristics are insufficient even in the frequency range. As is apparent from the comparison between the nonwoven fabric structure 1 and the nonwoven fabric structure C2 and the nonwoven fabric structure C3 in particular, the fiber density of the fiber body is too high, and the reflection of sound on the inside of the fiber body or on the surface of the fiber body becomes strong. In addition, since the penetration of the low-frequency sound into the fiber body and the absorption by the fiber body are insufficient, the non-woven fabric structures C3, C9 and C12 have a sufficient sound absorption effect due to the above-described resonance due to the decrease in thickness. This is probably because it was not expressed.

This application claims priority based on Japanese Patent Application No. 2014-263389 filed on December 25, 2014. The contents described in the application specification and the drawings are all incorporated herein.

The non-woven fabric structure according to the present invention has an effect specific to a fiber body using nanofibers, which is excellent in sound absorption characteristics in a low frequency range. Therefore, in addition to the effects unique to the nonwoven fabric structure such as air permeability, liquid permeability, and heat insulation, the nonwoven fabric structure is expected to have an additional effect of preventing the transmission of vibrations of low-frequency fluid. The Therefore, the non-woven fabric structure is expected to be used in applications as a sound absorbing material for absorbing lower frequency sound, and in various fields where prevention of the low frequency vibration is expected. It is expected to be used in various applications as a covering material, a separating material, a partition member, etc. that also have sound absorption characteristics.

DESCRIPTION OF SYMBOLS 1 Fiber body 2 Support body 10A-10E Nonwoven fabric structure

Claims

A sound-absorbing material comprising a nonwoven fabric structure having a fibrous body in which fibers are entangled,
The fiber includes a nanofiber made of polypropylene having a fiber diameter of less than 1 μm,
The thickness of the fibrous body is 20 mm or more and 36 mm or less,
The fiber density of the fibrous body is 10 kg / m 3 or more and less than 50 kg / m 3 ,
The content ratio of the nanofiber in the fibrous body is 0.5 or more by mass ratio,
A sound absorbing material having a sound absorption coefficient of 1 kHz sound of 0.59 to 0.84 and a sound absorption coefficient of 6 kHz sound of 0.80 to 0.96.
The sound absorbing material according to claim 1, wherein the nonwoven fabric structure further includes a support for supporting the fibrous body.
The sound-absorbing material according to claim 2, wherein the fibrous body is supported by the support on one side or sandwiched between the two supports.
The sound-absorbing material according to claim 2 or 3, wherein the nonwoven fabric structure has two or more fiber bodies, and has the support body at least between the fiber bodies.
The sound absorbing material according to any one of claims 2 to 4, wherein the support is one or more selected from the group consisting of a nonwoven fabric, a woven fabric, a film, paper, and a foam layer.
The sound absorbing material according to any one of claims 1 to 5, wherein the fibrous body further includes microfibers having a fiber diameter of 2 to 50 袖 m.