Sound absorber and sound absorption component

Abstract

To provide a sound absorber that improves convenience.SOLUTION: A sound absorber 10 comprises a fiber bundle structure 13 formed by bundling a plurality of hollow fibers 12 such that a first end surface 11 is formed of end faces of the plurality of hollow fibers 12 in a length direction D, wherein the plurality of hollow fibers 12 are open on the first end face 11 of the fiber bundle structure 13, and an angle θ of contact with a droplet L is 110° or larger.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to sound-absorbing materials and sound-absorbing components. [Background technology]

[0002] Conventionally, technologies related to sound-absorbing materials have been known. For example, Patent Document 1 discloses an acoustic insulation material that is lightweight, has excellent sound absorption and heat insulation properties, does not sink over time, does not emit substances that cause sick house syndrome, and is easy to install. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-307608 Summary of the Invention [Problem to be solved by the invention]

[0004] The sound-absorbing effect of porous sound-absorbing materials drops significantly when they absorb water. Therefore, when using porous sound-absorbing materials outdoors or in wet areas, they are treated with a water-repellent coating to protect them from rainwater and tap water. Fluorine-based water-repellents are the most common type of water-repellent, but there is a trend toward discontinuing their use due to the fact that they are suspected of being environmental pollutants and posing a health hazard.

[0005] There are also durability issues, such as the tendency for the water-repellent coating applied to the porous material to peel off or fall off. Other known techniques include creating irregularities on the surface of the porous material to create a water-repellent effect, and graft-polymerizing fluorine-based monomers onto the fiber surface using electron beam irradiation to achieve a water-repellent effect. However, the water-repellent effect disappears when the surface is worn away by physical actions such as friction, so durability is also an issue. As a result, the usefulness of sound-absorbing materials has decreased.

[0006] An object of the present disclosure is to provide a sound-absorbing material and a sound-absorbing part that are more convenient. [Means for solving the problem]

[0007] The sound-absorbing material to solve the above problems is a fiber bundle structure in which a plurality of hollow fibers are bundled together so that a first end face is formed by an end face in the length direction of each of the plurality of hollow fibers; The first end face of the fiber bundle structure is configured so that each of the plurality of hollow fibers is open and forms a contact angle with a liquid droplet of 110° or more.

[0008] The sound-absorbing parts that solve the above problems are: The above sound-absorbing material, a fixing material including a film or plate-like structure that closes a second end face of the fiber bundle structure opposite to the first end face; Equipped with. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a sound-absorbing material and a sound-absorbing component that improve convenience. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a sound-absorbing material according to an embodiment of the present disclosure. FIG. [Figure 2] 1 is a schematic diagram illustrating an example of a configuration of a sound-absorbing component according to an embodiment of the present disclosure. FIG. [Figure 3] 2 is a diagram showing an example of the configuration of a first end face of the sound-absorbing material of FIG. 1. FIG. [Figure 4] 10A and 10B are schematic diagrams illustrating an example of the configuration of a sound-absorbing component according to a modified example of the present disclosure. [Figure 5] FIG. 2 is a graph showing the sound absorbing effect of the sound absorbing material according to the first embodiment of the present disclosure. [Figure 6] 10A and 10B are diagrams showing the water-repellent effect of a sound-absorbing material according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following mainly describes a sound-absorbing material 10 and a sound-absorbing component 1 according to an embodiment of the present disclosure with reference to the accompanying drawings.

[0012] FIG. 1 is a schematic diagram showing an example of the configuration of a sound-absorbing material 10 according to an embodiment of the present disclosure. FIG. 1 shows a state in which droplets L of liquid are attached to a first end surface 11 of the sound-absorbing material 10. In this disclosure, "liquid" includes, but is not limited to, water, for example. "Liquid" may also include liquids other than water that form spherical droplets at the first end surface 11 of the sound-absorbing material 10 and are repelled. The sound-absorbing material 10 has, for example, water-repellent properties. That is, the sound-absorbing material 10 repels, for example, water that flows onto the first end surface 11 by forming spherical droplets L at the first end surface 11. This prevents liquids such as water from penetrating the interior of the sound-absorbing material 10, thereby reducing moisture absorption.

[0013] The sound-absorbing material 10 has a fiber bundle structure 13 in which a plurality of hollow fibers 12 are bundled together such that a first end face 11 is formed by the end faces of each of the plurality of hollow fibers 12 in the length direction D. The end faces of each of the plurality of hollow fibers 12 in the length direction D are aligned, for example, so as to be flush with each other at the first end face 11. For example, the first end face 11 is configured as a flat surface. This is not a limitation, and the end faces of each of the plurality of hollow fibers 12 in the length direction D may be arranged, for example, so as to be slightly shifted from being flush with each other at the first end face 11. For example, the first end face 11 may be configured as a curved surface. The plurality of hollow fibers 12 are arranged and bundled in parallel to each other along the length direction D.

[0014] An end 14 of the fiber bundle structure 13 located on the opposite side to the first end face 11 is configured by fixing the plurality of hollow fibers 12 to each other by at least one of fusion, adhesion, and cohesion. For example, the plurality of hollow fibers 12 may be fixed to each other at the end 14 of the fiber bundle structure 13 in a state where the resin constituting the hollow fibers 12 is heated and melted to fuse them. For example, the plurality of hollow fibers 12 may be fixed to each other at the end 14 of the fiber bundle structure 13 in a state where they are bonded to each other with an adhesive. For example, the plurality of hollow fibers 12 may be fixed to each other at the end 14 of the fiber bundle structure 13 in a state where the outer periphery of the bundle is wrapped with adhesive tape or the like.

[0015] 2 is a schematic diagram showing an example of the configuration of a sound-absorbing component 1 according to an embodiment of the present disclosure. A sound-absorbing material 10 is used as part of the sound-absorbing component 1 to obtain a sound-absorbing effect. The sound-absorbing component 1 includes the sound-absorbing material 10 and a fixing material 20 including a film or plate-like structure that closes a second end face 15 of the fiber-bundle structure 13 opposite to the first end face 11.

[0016] The fixing material 20 includes any object for fixing and positioning the sound-absorbing material 10 when obtaining a sound-absorbing effect. The object may be a membrane, or a plate-like structure including a wall such as a rigid wall, a sound-insulating material, or other solid object. The sound-absorbing component 1 exhibits properties such as water repellency at the first end surface 11 of the sound-absorbing material 10, and also exhibits a sound-absorbing effect by combining the sound-absorbing material 10 with the fixing material 20 that covers the second end surface 15 of the sound-absorbing material 10.

[0017] FIG. 3 is a diagram showing an example of the configuration of the first end surface 11 of the sound-absorbing material 10 of FIG. 1. The following describes in detail, as an example, the conditions under which the sound-absorbing material 10 exhibits water repellency at the first end surface 11 of the fiber-bundle structure 13. The first end surface 11 is formed by the end surfaces of each of the plurality of hollow fibers 12 in the length direction D. The first end surface 11 is formed by each of the plurality of hollow fibers 12 being open. The first end surface 11 is configured so that the contact angle with the liquid droplet L is 110° or greater by satisfying the following conditions: The contact angle with the liquid droplet L at the first end surface 11 is preferably 110° or greater, more preferably 120° or greater, and even more preferably 123° or greater.

[0018] The material of the hollow fibers 12 is, for example, a material whose surface free energy is lower than the surface tension of water. A material with a low surface free energy of the hollow fibers 12 enhances its water-repellent effect. One example of such a material is PMP (Poly Methyl Pentene) resin, a material with a low surface free energy second only to fluororesin. The material is not limited to this, and may be any other resin with low surface free energy, such as PP (Polypropylene) resin. The surface free energy of the resin material constituting the hollow fibers 12 at room temperature may be equal to or lower than 72.7 mN / m, which is the surface tension of water.

[0019] For example, the diameter L1 of the hollow fibers 12 must be equal to or less than a first predetermined value. Since water repellency according to the Cassie-Baxter theory is believed to be exhibited, it is estimated that water repellency decreases when the area fraction occupied by the resin portion, calculated by subtracting the pore diameter L3 from the diameter L1 of the hollow fibers 12, is large. When bundling hollow fibers 12 to form a fiber bundle structure 13, the distance L2 between the hollow fibers 12 must be equal to or less than a second predetermined value. For example, if the distance L2 is long and the gaps between the hollow fibers 12 are large, water will penetrate into the gaps. The pore diameter L3 of the hollow fibers 12 must be equal to or less than a third predetermined value. For example, if the pore diameter L3 is large, water will penetrate into the holes located at the center of the hollow fibers 12.

[0020] The area fraction can be considered as a parameter that comprehensively expresses the above conditions. For example, the area fraction of the area of ​​the resin that constitutes the multiple hollow fibers 12 relative to the total area of ​​the first end surface 11 is greater than 40% and less than 74%. The lower limit of the area fraction is not limited to 40%, and may more preferably be 45%. The upper limit of the area fraction is not limited to 74%, and may more preferably be 60%, more preferably 55%, or even more preferably 49%.

[0021] 3, the resin portions constituting the plurality of hollow fibers 12 are shown whiter, and the void portions interposed between the resin portions are shown darker. For example, when the resin portions of the hollow fibers 12 occupy 73% of the entire first end face 11, which is the water-repellent surface, the contact angle approaches 110°, the minimum value for high water repellency. Therefore, it is preferable to specify the ratio of the resin portions and void portions occupying the water-repellent surface using an area fraction.

[0022] The sound-absorbing material 10 and sound-absorbing component 1 according to one embodiment described above provide improved convenience. The sound-absorbing material 10 has a fiber bundle structure 13 in which a plurality of hollow fibers 12 are bundled together such that a first end face 11 is formed by the end faces in the length direction D of each of the hollow fibers 12. The first end face 11 of the fiber bundle structure 13, which is formed by the plurality of end faces, is configured so that each of the hollow fibers 12 is open and forms a contact angle with a liquid droplet L of 110° or more. This makes it easy for the sound-absorbing material 10 to achieve water repellency.

[0023] For example, in conventional technology, a water-repellent treatment is separately applied to porous bodies such as sponge, foam, glass fiber, glass wool, chemical fiber, natural fiber, metal fiber, sintered porous metal, and sintered porous plastic. In contrast, the sound-absorbing material 10 according to an embodiment of the present disclosure does not require a chemical water-repellent treatment. The sound-absorbing material 10 can be easily constructed by simply bundling hollow fibers 12 under the above-described conditions, eliminating the need for processes such as coating and electron beam irradiation.

[0024] In addition, because sound-absorbing material 10 does not have a coating, the coating does not fall off due to deterioration or wear of the coating. Even if first end face 11, which is the water-repellent surface, is physically worn away due to wear, sound-absorbing material 10 can easily maintain its water-repellent effect because hollow fibers 12 are similarly arranged in the layer below.

[0025] In addition, a new water-repellent surface can be easily created in the sound-absorbing material 10 by intentionally cutting the surface of the first end face 11 or by cutting the fiber bundle structure 13 with a blade near the first end face 11. Therefore, even if dirt adheres to the first end face 11 of the sound-absorbing material 10 and the water-repellent effect is reduced, the water-repellent effect can be easily reproduced with a new water-repellent surface by cutting or scraping the water-repellent surface. The water-repellent effect of the sound-absorbing material 10 can be easily reproduced by simply cutting the first end face 11, rather than by applying an additional coating as in conventional technology.

[0026] The sound-absorbing material 10 can easily achieve a water-repellent effect without using a fluorine-based water-repellent agent, etc. This allows the sound-absorbing material 10 to reduce environmental pollution and damage to human health.

[0027] At the first end surface 11, the area fraction of the area of ​​the resin that constitutes the plurality of hollow fibers 12 relative to the total area of ​​the first end surface 11 is greater than 40% and less than 74%. This makes it possible for the sound-absorbing material 10 to easily maintain the contact angle between the first end surface 11 and the liquid droplet L at 110° or greater.

[0028] The surface free energy at room temperature of the resin material that makes up the hollow fibers 12 is equal to or less than the surface tension of water, 72.7 mN / m, which allows the sound-absorbing material 10 to have high water repellency. By using a material with low surface free energy, the sound-absorbing material 10 can achieve a sufficient water-repellent effect.

[0029] An end 14 of the fiber bundle structure 13 located on the opposite side to the first end face 11 is configured by fixing the plurality of hollow fibers 12 to one another by at least one of fusion, adhesion, and cohesion. This allows the sound-absorbing material 10 to fix the relative positions of the plurality of hollow fibers 12 to one another, thereby stably maintaining the fiber bundle structure 13.

[0030] The sound-absorbing component 1 includes the sound-absorbing material 10 and a fixing member 20, including a membrane or plate-like structure, that closes the second end face 15 of the fiber bundle structure 13 opposite the first end face 11. This allows the sound-absorbing component 1 to easily achieve a sound-absorbing effect by combining the sound-absorbing material 10 and the fixing member 20. For example, the sound-absorbing component 1 uses hollow fibers 12 in the fiber bundle structure 13 of the sound-absorbing material 10, which can improve the sound-absorbing effect by converting acoustic energy into thermal energy using the hollow fibers 12. That is, the fine sponge structure of the hollow fibers 12 themselves in the sound-absorbing material 10 can also contribute to sound absorption. More precisely, if the resin portion of the hollow fibers 12, calculated by subtracting the pore diameter L3 from the fiber diameter L1, has a sponge structure, i.e., a porous structure, when sound waves pass through the small pores of the hollow fibers 12, some of the acoustic energy is consumed as thermal energy due to friction with the surrounding walls of the resin portion, viscous resistance, and fiber vibration. When the resin portion has a porous structure, it is believed that the sound absorbing effect is higher than when the resin portion does not have a porous structure. The sound absorption coefficient of the sound absorbing material 10 is believed to depend on the fiber diameter L1 of the hollow fibers 12 in the fiber bundle structure 13 and other fine structures.

[0031] As described above, the sound-absorbing material 10 can be used as a water-repellent sound-absorbing material. The sound-absorbing material 10 can be used in bathrooms, outdoors, and other wet areas. In this case, the sound-absorbing material 10 can also achieve a sound-absorbing effect, i.e., soundproofing effect, by being used in combination with a fixed material 20 such as a rigid wall or sound-insulating material.

[0032] 4 is a schematic diagram showing an example of the configuration of a sound-absorbing component 1 according to a modified example of the present disclosure. In the above embodiment, the sound-absorbing component 1 has been described as including a sound-absorbing material 10 and a fixing material 20 including a membrane or plate-like structure that closes the second end face 15 of the fiber-bundle structure 13 opposite the first end face 11, but this is not limiting. The sound-absorbing component 1 may further include another porous body 30 disposed between the sound-absorbing material 10 and the fixing material 20. In this case, the multiple hollow fibers 12 are configured so that they are each open on the side of the other porous body 30, just like the first end face 11.

[0033] That is, the second end face 15 of the fiber bundle structure 13 opposite to the first end face 11 is configured so that each of the plurality of hollow fibers 12 is open and connected to the other porous body 30. The other porous body 30 includes any porous body that can achieve a sound absorbing effect together with the sound-absorbing material 10 in the sound-absorbing component 1. The other porous body 30 includes, for example, sponge, foam, glass fiber, glass wool, chemical fiber, natural fiber, metal fiber, sintered metal porous body, and sintered plastic porous body.

[0034] By connecting the second end face 15 of the fiber bundle structure 13 opposite to the first end face 11 to the other porous body 30, the sound-absorbing material 10 can contribute to improving the sound absorption effect together with the other porous body 30. By having the sound-absorbing material 10 and the other porous body 30, the sound-absorbing component 1 can further improve the sound absorption effect compared to when only the sound-absorbing material 10 is arranged on the fixing material 20. [Example]

[0035] The sound-absorbing material 10 according to an embodiment of the present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples. The numerical values ​​described in the examples are merely examples and do not limit the scope of the present disclosure. The scope of the present disclosure should be determined solely based on the claims. Below, components similar to those in the embodiment will be assigned the same reference numerals, and duplicate explanations will be omitted.

[0036] Fig. 5 is a graph showing the sound absorption effect of the sound-absorbing material 10 according to Example 1 of the present disclosure. The vertical axis of the graph shown in Fig. 5 represents sound absorption coefficient, and the horizontal axis represents frequency. The solid line graph shows the frequency dependence of the sound absorption coefficient of the sound-absorbing material 10 according to Example 1. The dashed line graph shows the frequency dependence of the sound absorption coefficient of the sound-absorbing material according to Comparative Example 1. The two-dot chain line graph shows the frequency dependence of the sound absorption coefficient of the sound-absorbing material according to Comparative Example 2.

[0037] To confirm the sound absorption effect of the sound-absorbing material 10 according to an embodiment of the present disclosure, the normal incidence sound absorption coefficient of an acoustic tube was measured for each of Example 1, Comparative Example 1, and Comparative Example 2 using the transfer function method. Details of the sound absorption coefficient measurement method are as follows. The normal incidence sound absorption coefficient was measured using the two-microphone transfer function method in accordance with JIS A 1405-2:2007 (ISO 10534-2, ASTM E 1050). A Brüel & Kjær 4206T transmission loss tube kit was used as the measurement device. A thin tube with an inner diameter of 29 mm, designed for high-frequency measurements, was selected as the tube type. To measure the normal incidence sound absorption coefficient, the thin tube was attached to the opening of a thick tube equipped with a speaker, and then a thin tube sample holder containing a sample was attached to the thin tube, thereby measuring the sound absorption coefficient. The sound-absorbing material 10 according to Example 1 has the same configuration as that shown in FIG. 1 . The thickness of the fiber bundle structure 13 in the sound-absorbing material 10, i.e., the length of each hollow fiber 12 in the longitudinal direction D, is 10 mm. The sound-absorbing material of Comparative Example 1 is, for example, a coarse-pile felt having a thickness of 10 mm, similar to Example 1. The sound-absorbing material of Comparative Example 2 is, for example, a urethane sponge having a thickness of 10 mm, similar to Example 1.

[0038] 5, the sound-absorbing material 10 of Example 1 exhibits a higher sound absorption coefficient than the sound-absorbing material of Comparative Example 1 and the sound-absorbing material of Comparative Example 2 in almost all bands in the frequency range measured. In all of Example 1, Comparative Example 1, and Comparative Example 2, the sound absorption coefficient tends to increase as the frequency increases, but in frequency bands above 1000 Hz, the sound-absorbing material 10 of Example 1 exhibits a clearly higher sound absorption coefficient than the other two comparative examples. As described above, it was confirmed that the sound-absorbing material 10 of Example 1 has a sound absorption coefficient equal to or greater than that of a general sound-absorbing material such as coarse wool felt.

[0039] FIG. 6 is a diagram showing the water-repellent effect of a sound-absorbing material 10 according to an embodiment of the present disclosure. As shown in FIG. 6, a predetermined liquid is dropped onto the first end surface 11 of the fiber-bundle structure 13 to form a droplet L. At this time, the contact angle θ is the angle between the free surface of the droplet L and the first end surface 11 with which the droplet L is in contact. As shown in FIG. 6, the contact angle θ is an obtuse angle rather than an acute angle. As shown in Table 1 below, the contact angle θ is 110° or more, which indicates high water repellency, in each of Examples 1 to 3.

[0040] [Table 1] Table 1 shows the water-repellent effect of the sound-absorbing material 10 according to each of Examples 1 to 3 of the present disclosure. The columns of Table 1 list items such as area fraction [%], contact angle [°] (theoretical value), and contact angle [°] (measured value). The contact angle [°] (theoretical value) indicates the value of the contact angle derived from the Cassie-Baxter theory using each of the area fractions in Table 1. The contact angle [°] (measured value) indicates the value actually measured as the contact angle θ from photographic data such as that shown in FIG. 6.

[0041] To confirm the water-repellent effect of the sound-absorbing material 10 according to an embodiment of the present disclosure, the area fraction of the area of ​​the resin constituting the plurality of hollow fibers 12 at the first end face 11 relative to the total area of ​​the first end face 11 was calculated for each of Examples 1 and 3. Image acquisition and binarization processing methods for calculating the area fraction will now be described in detail.

[0042] First, the first end face 11, which is the opening face of the fiber bundle structure 13, was imaged using an optical microscope. The optical microscope used was a "Microscope VHX-8000" manufactured by Keyence Corporation. The lens used was a ZS-20. The tilt angle was 0 degrees, the illumination method was coaxial unidirectional, and the brightness was 255, which was the maximum value for the device. Furthermore, the shutter speed was 3.00 ms, the gain was 0 dB, and the imaging magnification was 100x.

[0043] The image of the first end face 11 captured by the optical microscope was subjected to image processing using free software PickMap version 2.7. The brightness of the captured image (hereinafter referred to as "luminance") was divided into 256 gradations from 0 to 255 by image processing, and the occurrence frequency of each luminance was calculated. Next, using 98 as the luminance threshold, the resin portion and void portion of the hollow fiber 12 were binarized, and the area fraction of the resin portion was calculated. Here, the luminance used to distinguish between black and white was the average value of RGB.

[0044] In each of Examples 1 to 3, a sound-absorbing material 10 having a configuration similar to that shown in Fig. 1 was prepared, and the area fraction was calculated using the method described above. In Examples 1, 2, and 3, the area fractions were 49%, 47%, and 45%, respectively. In contrast, the case where the area fraction was 39%, which was below 40%, was defined as Comparative Example 3. On the other hand, the case where the area fraction was 100%, which was above 74%, was defined as Comparative Example 4. In Comparative Example 4, where the area fraction was 100%, a plate made of the same material as the hollow fibers 12 was used instead of a bundle of hollow fibers 12 in place of the fiber bundle structure 13.

[0045] In Example 1, where the area fraction is 49%, the theoretical value of the contact angle is 124°, while the measured value of the contact angle θ is 123°. In Example 2, where the area fraction is 47%, the theoretical value of the contact angle is 125°, while the measured value of the contact angle θ is 126°. In Example 3, where the area fraction is 45%, the theoretical value of the contact angle is 126°, while the measured value of the contact angle θ is 124°. Measurement of the contact angle θ confirmed that the average of the contact angles θ was 126°, including Examples 1 to 3. As such, the sound-absorbing material 10 exhibits an average contact angle θ that exceeds 110°, the minimum value for high water repellency, and exhibits sufficient water repellency.

[0046] Comparative Example 3 shows that if the area fraction of the hollow fibers 12 is made too low, i.e., if the area fraction of the voids is made too high, the contact angle θ becomes small and deviates from the Cassie-Baxter theory. If the area fraction of the voids is too high as in Comparative Example 3, i.e., if the distance L2 between the hollow fibers 12 is too long or the pore diameter L3 is too large, the liquid droplets L penetrate into the fiber bundle structure 13 through the voids and are not repelled.

[0047] Comparative Example 4 shows that if the area fraction of hollow fibers 12 is made too high, i.e., if the area fraction of voids is made too low, the contact angle θ becomes small and deviates from the Cassie-Baxter theory. If the area fraction of voids is set to 0 and the first end face 11 is made entirely of resin, as in Comparative Example 4, the voids disappear and only the water repellency resulting from the resin portion is obtained, making it difficult for the droplets L to be repelled.

[0048] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms other than the above-described embodiments without departing from the spirit or essential characteristics thereof. Therefore, the foregoing description is illustrative and not limiting. The scope of the disclosure is defined not by the foregoing description but by the appended claims. All modifications within the range of equivalents of any modifications are intended to be embraced therein.

[0049] For example, the shape, pattern, size, arrangement, orientation, type, and number of each of the above-mentioned components are not limited to those shown in the above description and drawings. The shape, pattern, size, arrangement, orientation, type, and number of each component may be configured arbitrarily as long as the function can be realized. The illustrated components of the sound-absorbing material 10 and sound-absorbing component 1 are functional concepts. The specific form of each component is not limited to those shown in the drawings.

[0050] In addition, the sound-absorbing material 10 may be manufactured to have a structure similar to that shown in Figure 1 using additive manufacturing, i.e., layered manufacturing such as a 3D printer, instead of or in addition to the hollow fibers 12, using a material with low surface free energy, to achieve a similar effect.

[0051] Some embodiments of the present disclosure will be described below as examples, however, it should be noted that the embodiments of the present disclosure are not limited to these. [Appendix 1] a fiber bundle structure in which a plurality of hollow fibers are bundled together so that a first end face is formed by an end face in the length direction of each of the plurality of hollow fibers; The first end surface of the fiber bundle structure is configured so that each of the plurality of hollow fibers is open and forms a contact angle with a liquid droplet of 110° or more. Sound-absorbing material. [Appendix 2] 10. The sound-absorbing material according to claim 1, At the first end surface, the area fraction of the area of ​​the resin constituting the plurality of hollow fibers relative to the total area of ​​the first end surface is greater than 40% and smaller than 74%. Sound-absorbing material. [Appendix 3] 3. The sound-absorbing material according to claim 1 or 2, The surface free energy of the resin material constituting the hollow fiber at room temperature is 72.7 mN / m or less, which is the surface tension of water. Sound-absorbing material. [Appendix 4] 4. A sound-absorbing material according to any one of claims 1 to 3, an end portion of the fiber bundle structure located opposite to the first end surface is configured by fixing the plurality of hollow fibers to each other by at least one of fusion, adhesion, and cohesion; Sound-absorbing material. [Appendix 5] 5. A sound-absorbing material according to any one of claims 1 to 4, a second end face of the fiber bundle structure opposite to the first end face, in which each of the plurality of hollow fibers is open and connected to another porous body; Sound-absorbing material. [Appendix 6] A sound-absorbing material according to any one of Supplementary Notes 1 to 4; a fixing material including a film or plate-like structure that closes a second end face of the fiber bundle structure opposite to the first end face; Equipped with Sound absorbing parts. [Explanation of symbols]

[0052] 1. Sound-absorbing parts 10 Sound-absorbing material 11 First end surface 12 Hollow Fiber 13 Fiber bundle structure 14 End 15 Second end face 20 Fixing material 30 Other porous materials L droplet L1 wire diameter L2 distance L3 hole diameter θ contact angle

Claims

1. a fiber bundle structure in which a plurality of hollow fibers are bundled together such that a first end face is formed by an end face in a longitudinal direction of each of the plurality of hollow fibers; the first end surface of the fiber bundle structure is configured so that each of the plurality of hollow fibers is open and forms a contact angle with a liquid droplet of 110° or more; Sound-absorbing material.

2. 2. The sound-absorbing material according to claim 1, At the first end surface, an area fraction of the area of ​​the resin constituting the plurality of hollow fibers relative to a total area of ​​the first end surface is greater than 40% and smaller than 74%. Sound-absorbing material.

3. The sound-absorbing material according to claim 1 or 2, The surface free energy of the resin material constituting the hollow fiber at room temperature is 72.7 mN / m or less, which is the surface tension of water. Sound-absorbing material.

4. The sound-absorbing material according to claim 1 or 2, an end portion of the fiber bundle structure located opposite to the first end surface is configured by fixing the plurality of hollow fibers to each other by at least one of fusion, adhesion, and cohesion; Sound-absorbing material.

5. The sound-absorbing material according to claim 1 or 2, a second end face of the fiber bundle structure opposite to the first end face, the second end face being configured so that each of the plurality of hollow fibers is open and connected to another porous body; Sound-absorbing material.

6. The sound-absorbing material according to claim 1 or 2; a fixing material including a film or plate-like structure that closes a second end face of the fiber bundle structure opposite to the first end face; Equipped with Sound absorbing parts.

Images