JPH10237978A - Sound-absorbing material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound-absorbing material, which has excellent sound- absorbing characteristics even in a low frequency band and in which the deterioration of sound-absorbing performance due to deviation by the movement, etc., of powder can be prevented. SOLUTION: Powder 4 is mixed with fiber collecting materials 7, in which fibers 3 having core sheath structure, in which the surfaces of core materials are covered with covering materials having the melting point lower than the melting point of the core materials, and fibers 6 having shape restoring force larger than the fibers 3 having the core sheath structure coexist. The fibers and the fibers and at least parts of powder 4 and the fibers are fused by the covering materials of the fibers 3 having core sheath structure. The movement of the powder 4 can be prevented by fusing the powder to the fibers 3. The sound-absorbing material, in which bulkiness is held by the fibers 6 having large shape restoring force can be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material used for sound processing in a listening room, a musical instrument practice room, and the like, and for reducing noise propagating in an air conditioning duct, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A sound-absorbing material is used in a listening room or a musical instrument practice room or the like where the acoustic characteristics of a room are problematic. It is used as a filling material that fills the walls and ceiling formed in the building, a lining material that stretches to the side of the air conditioning duct to prevent the propagation of noise, and a lining material that stretches inside the soundproof cover of equipment that generates noise. .

As a sound absorbing material used in such applications, porous sound absorbing materials such as glass wool, rock wool, and polyurethane foam have been mainly used. Since these porous sound-absorbing materials have voids that communicate with each other, when sound waves enter the voids, viscous friction occurs between the surface of the fiber and the wall surface of the urethane bubble during propagation in the voids, and the acoustic wave Sound is absorbed by absorbing energy into the material.

[0004] However, these porous sound absorbing materials have a sufficient sound absorption coefficient in a high frequency range, but the sound absorption rate decreases as the sound frequency decreases, and it is not possible to obtain a sufficient sound absorption rate in a low frequency range. There's a problem. Increasing the thickness of the porous sound-absorbing material increases the sound absorption rate in the low-frequency range, but the sound-absorbing material becomes extremely bulky, and, for example, when used as an interior material for a room, there is a problem that the room becomes narrow, When used as the lining of an air-conditioning duct, problems such as a narrow air passage arise.

Accordingly, a sound absorbing material formed of a powder layer such as silica powder has been provided as a sound absorbing material having excellent sound absorbing performance in a low frequency range even though it is thin. In this sound absorbing material,
When sound is incident on the powder layer, the powder particles vibrate, and the sound wave energy is absorbed by the vibration, thereby exhibiting a sound absorbing effect. However, the sound absorbing material made of this powder is
For example, filling a powder in a box-shaped container to form a powder layer,
It can be formed by covering with a film etc. with good sound transmission, but even if the container is evenly filled with powder, the powder gradually moves in the process of use and the powder is biased, and the sound absorption performance There is a problem that may change. Also, the sound absorbing material can be formed by filling and holding the powder in the pores of a very coarse porous material such as glass wool, but also in this case, the powder is initially filled uniformly. Even in this case, there is a possibility that the powder gradually moves and becomes unbalanced in the use process, and the sound absorbing performance similarly changes.

Further, JP-A-5-323973, JP-A-6-110468, and JP-A-6-158748
Japanese Patent Application Publication No. JP-A-2005-64139 and the like provide a sound absorbing material having a structure in which a powder layer is alternately laminated with a fiber layer. However, even in this case, the powder in the powder layer remains in a free state, and the problem due to the movement of the powder has not been solved. In contrast, Japanese Patent Application Laid-Open No. 8-39
No. 596 discloses a sound-absorbing material in which a foamable resin binder is interposed in the voids of fibers, and the powder is held by the foamable resin binder. However, in this case, since the ratio of the powder in the sound absorbing material is reduced by the foamable resin binder, there is a problem that the sound absorbing characteristics in a low frequency range due to the powder are deteriorated. There is also a problem that the production becomes complicated because a foamable resin binder is used.

[0007]

Accordingly, the present invention provides a sound-absorbing material which has good sound-absorbing characteristics even in a low-frequency range, and which can prevent the sound-absorbing performance from deteriorating due to bias due to powder movement or the like. It is another object of the present invention to provide a method of manufacturing a sound absorbing material that can easily manufacture such a sound absorbing material.

[0008]

According to a first aspect of the present invention, there is provided a sound-absorbing material comprising a core-sheath structure fiber in which the surface of a core is coated with a coating having a melting point lower than the melting point of the core. The powder 4 is mixed with the fiber aggregate 7 in which the fiber 6 having a greater shape restoring force than the fiber 3 having the core-sheath structure coexists. Characterized in that at least a part of the fiber is fused to the fiber.

The sound absorbing material according to claim 2 of the present invention is a core material 1
A fiber aggregate 7 in which a core-sheath structure fiber 3 whose surface is covered with a coating material 2 having a melting point lower than the melting point of the core material 1 and a fiber 6 having a greater shape restoring force than the core-sheath structure fiber 3 coexist The fibers 4 are mixed with the fibers 4 and the fibers and at least a part of the powders 4 are fusion-bonded to each other by the covering material 2 of the fibers 3 having the core-sheath structure. 8 are joined.

The invention according to claim 3 is characterized in that the powder 4 is talc. Claim 4
The present invention is characterized in that the powder 4 is a shirasu balloon. The invention according to claim 5 is characterized in that the above-mentioned sound absorbing material is laminated with a porous material 9.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a sound-absorbing material, comprising: a core-sheath fiber 3 in which the surface of a core material 1 is coated with a coating material 2 having a melting point lower than the melting point of the core material 1; The powder 4 is mixed with the fiber aggregate 7 in which the fiber 6 having a larger shape restoring force than the fiber 3 having the sheath structure coexists, and this is heated at a temperature equal to or higher than the melting temperature of the coating material 2 of the fiber 3 having the core-sheath structure. By
At least a part of the fiber and the fiber and the powder 4 are bonded to the fiber by fusing the coating material 2.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a sound-absorbing material, comprising: a core-sheath structure fiber in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material; The powder 4 is mixed with the fiber aggregate 7 in which the fiber 6 having a larger shape restoring force than the fiber 3 having the sheath structure coexists, and the surface material 8 is further superimposed on the surface of the fiber aggregate 7 to form a core-sheath structure. By heating the fiber 3 at a temperature equal to or higher than the melting temperature of the coating material 2, the fiber is bonded to at least a part of the fiber and the powder 4 by the fusion of the coating material 2 and the surface of the fiber aggregate 7 is bonded to the surface. It is characterized in that the members 8 are joined.

[0013] The method for producing a sound absorbing material according to claim 8 of the present invention comprises a core-sheath structure fiber 3 in which the surface of a core material 1 is coated with a coating material 2 having a melting point lower than the melting point of the core material 1; After adhering a surface material 8 to one surface of a fiber aggregate 7 in which a fiber 6 having a greater shape restoring force than the fiber 3 having a sheath structure coexists, a powder 4 is mixed with the fiber aggregate 7, and this is used as a core. By heating at a temperature equal to or higher than the melting temperature of the coating material 2 of the sheathed fiber 3, the fiber is bonded to at least a part of the fiber and the powder 4 by fusion of the coating material 2. It is.

According to a ninth aspect of the present invention, there is provided a fiber 3 having a core-sheath structure in which the surface of a core material 1 is coated with a coating material 2 having a melting point lower than the melting point of the core material 1, and a shape formed by the fiber 3 having the core-sheath structure. It is characterized in that a fiber aggregate 7 in which fibers 6 having a large restoring force coexist is produced as a material whose fiber density changes in the thickness direction, and a powder 4 is mixed with the fiber aggregate 7. .

[0015]

Embodiments of the present invention will be described below. The fiber 3 having a core-sheath structure used in the present invention is formed into a two-layer structure as shown in FIG. 2 by coating the outer periphery of a core material 1 serving as a fiber main body with a coating material 2. The core material 1 can be formed of organic fibers or inorganic fibers,
Organic fibers include synthetic resin fibers such as polyester, nylon, polyacrylonitrile, polypropylene, polyethylene, and polyvinyl chloride, wood fibers, cotton,
Natural fibers such as hemp, bamboo, linter, silk, wool and the like and regenerated fibers such as rayon can be exemplified. As inorganic fibers, fibers such as rock fiber, glass, alumina, silicon carbide, carbon, steel and the like are exemplified. be able to.

The coating material 2 coated on the core material 1 made of organic fibers or inorganic fibers is formed of a material having a melting point lower than the melting point of the core material 1. Coating material 2 is core material 1
The material is not particularly limited as long as the material has a lower melting point than the above. For example, the material may be formed of the above-mentioned organic fiber material.
It is preferably about 0 ° C. lower, and 40 to 60 ° C.
More preferably, it is low. Core sheath fiber 3
It is preferable that the core material 1 and the coating material 2 have a weight ratio of 30:70 to 50:50.

The fiber 3 having a core-sheath structure in which the outer periphery of the core material 1 is coated with the coating material 2 is not particularly limited, but preferably has a fiber diameter in the range of 1 to 15 denier. The fiber length is preferably in the range of 5 to 100 mm. On the other hand, the fiber 6 having a larger shape restoring force than the core-sheath structure fiber 3 has a higher so-called stiffness than the core-sheath structure fiber 3. Fibers of the same material as the constituent fibers,
A fiber having a higher denier than the core-sheath structure fiber 3 can be used.

On the other hand, the powder 4 in the present invention can be used without any particular limitation, but includes gold mica, silica, acrylic resin, talc, shirasu balloon,
Powders of calcium silicate, fluororesin, perlite, fused silica, graphite, crystalline cellulose, silicon carbide, diatomaceous earth, nylon, polyester, carbon fiber, titanium dioxide, calcium carbonate, polyvinyl chloride, polymethyl methacrylate, barium ferrite, silicone, etc. These can be exemplified, and one or more of these can be used in combination. Of these, talc is preferably used as the powder 4 in order to obtain a high sound absorbing effect in a low frequency range. In addition, by using a shirasu balloon, it is possible to obtain a high sound absorbing effect particularly in a middle and low frequency range. The powder 4 preferably has a particle size in the range of 0.1 to 1000 μm, and the bulk density of the powder 4 is 0.1 to 1.5 μm.
The range is preferably about g / cm ³ .

In manufacturing the sound absorbing material A using the above-mentioned fiber 3 having the core-sheath structure, the fiber 6 having a large shape restoring force, and the powder 4, first, the fiber 3 having the core-sheath structure and the fiber 6 having a large shape restoring force are used. Are entangled to form a web (sheet), and a fiber aggregate 7 in which fibers 3 having a core-sheath structure and fibers 6 having a large shape restoring force coexist is prepared. Next, the powder 4 is sprinkled from above onto the web-like fiber aggregate 7 and mechanical vibration is applied to the fiber aggregate 7 so that the powder 4 is filled into the voids inside the fiber aggregate 7, Assembly material 7
And the powder 4 are mixed.

Here, in the case of preparing a web-like fiber aggregate 7 by assembling only the fibers 3 having a core-sheath structure, the fibers 3 having a core-sheath structure become weak due to the influence of the coating material 2 having a low melting point on the surface. Since the shape restoring force is small, the fiber aggregate 7 cannot maintain the thickness, and the thickness becomes thin and the bulkiness becomes small.
Therefore, in this material, the gap between the fibers of the fiber aggregate 7 becomes small, and the powder 4 becomes difficult to enter the fiber aggregate 7, and the powder 4 is uniformly dispersed and mixed in the fiber aggregate 7. It becomes difficult to do. Therefore, in the present invention, the fiber aggregate 7 is prepared by coexisting the fiber 6 having a larger shape restoring force than the fiber 3 having the core-sheath structure, and the fiber 6 having the large shape restoring force reduces the thickness of the fiber aggregate 7. By holding, the bulkiness of the fiber aggregate 7 can be increased. Therefore, in the fiber aggregate 7 of the present invention, the voids between the fibers are large, and the powder 4 can easily enter the inside of the fiber aggregate 7, and the powder 4 is uniformly dispersed in the fiber aggregate 7. And can be mixed. The mixing ratio of the fiber 3 having a core-sheath structure and the fiber 6 having a large shape restoring force is preferably in the range of 5: 5 to 3: 7 by weight.

The mixing amount of the powder 4 with respect to the web-like fiber aggregate 7 is set so that the amount of the powder 4 is in the range of 100 to 5000 parts by weight with respect to 100 parts by weight of the fiber aggregate 7. preferable. Powder 4 is added to fiber aggregate 7 as described above.
Is heated at a temperature about 30 to 40 ° C. higher than the melting point of the coating material 2 of the core-sheath structure fiber 3. The heating temperature is set at a temperature lower than the melting point of the core material 1 of the core-sheath fiber 3 and the melting point of the fiber 6 having a large shape restoring force (and lower than the melting point of the powder 4). Although the material 1 and the fiber 6 having a large shape restoring force do not melt, the coating material 2 melts, so that the entangled fibers 3 and 6 are fused at the intersection of the coating material 2 and the fibers 3 and 6 are joined together. Can be formed into a microscopic network structure. The powder 4 is fused to the coating material 2 by the melting of the coating material 2 by this heating, and is adhered to the fiber 3 and held. Ideally, all of the powder 4 is fused and held to the fiber 3, but this is not necessary. It is sufficient that at least a part of the powder 4 is fused to the fiber 3, and it is sufficient that about 10% by weight or more of the powder 4 is fused and held to the fiber 3.

As described above, it is possible to obtain a sound absorbing material A as shown in FIG. 1 in which the fibers 3 and 6 and at least a part of the fiber 3 and the powder 4 are fused. In A, the powder 4 is held in the voids of the fiber aggregate 7, so that the movement of the powder 4 due to vibration during use can be suppressed, and the low frequency sound absorbing characteristics of the powder 4 can be utilized. In addition, it is possible to prevent the sound absorbing performance from deteriorating due to the movement and bias of the powder 4. Further, since the fiber 6 having a larger shape restoring force than the fiber 3 having the core-sheath structure coexists with the fiber aggregate 7 of the sound absorbing material A, the sound absorbing material A can maintain a bulky thickness. It is possible to prevent the sound absorbing characteristic from deteriorating due to the reduction in thickness.

FIG. 3 shows an embodiment of a sound absorbing material A produced by joining a surface material 8 to the surface of a fiber aggregate 7. The surface material 8 may be anything as long as it does not allow the powder 4 to pass through, and a nonwoven fabric of synthetic resin fiber or glass fiber, or a sheet material such as paper or film can be used. The surface material 8 may be bonded to one surface of the fiber aggregate 7 or to both surfaces of the fiber aggregate 7, but both surfaces are preferably covered with the surface material 7. .

As described above, the surface of the fiber aggregate 7 is
In the sound absorbing material A covered with, the gap between the fibers 3 and 6 on the surface of the fiber aggregate 7 is closed by the surface material 8, and the powder 4 may fall off or move from the gap of the fiber aggregate 7. Can be prevented, and the bias due to the movement of the powder 4 can be further reduced. Further, the surface material 8 is bonded to the fibers 3 and 6 on the surface of the fiber aggregate 7 so that the surface material 8 is tied to the fibers 3 and 6. It is possible to prevent the powder 4 from moving to the generated space, and to further reduce the bias of the powder 4 in this respect.

The surface material 8 is applied to the surface of the fiber aggregate 7.
In producing the sound absorbing material A in which the powder 4 is mixed with the fiber aggregate 7 as described above,
The surface material 8 is superimposed on one or both surfaces of the core material, and in this state, the temperature is higher than the melting point of the coating material 2 of the core-sheath structure fiber 3 (and the core material 1 of the core-sheath structure fiber 3 has a large shape restoring force). This can be performed by heating at a temperature lower than the melting points of the fibers 6, the powder 4, and the surface material 8). The surface material 8 can be joined to the surface. Of course, the surface material 8 is bonded to the surface of the fiber aggregate 7 using the fusion to the fiber 3 having the core-sheath structure, and the surface material 8 is bonded to the surface of the fiber aggregate 7 using an adhesive. You may make it.

In producing the sound absorbing material A in which the surface material 8 is joined to the surface of the fiber aggregate 7, first, the fiber 3 having the core-sheath structure and the fiber 6 having a large shape restoring force are mixed as described above. Web-like fiber aggregate 7 in which both fibers 3 and 6 coexist
Is prepared, a surface material 8 is bonded and bonded to one surface of the fiber aggregate 7 and the powder 4 is sprayed from above onto the fiber aggregate 7 with the surface material 8 facing downward, and mixed. Later, if necessary, another surface material 8 is stacked on the upper surface of the fiber aggregate 7,
This temperature is higher than the melting point of the coating material 2 of the core-sheath structure fiber 3 (and the melting point of the core material 1 of the core-sheath structure fiber 3, the fiber 6 having a large shape restoring force, the powder 4, and the surface material 8). It may be performed by heating at a low temperature. Before the powder 4 is sprinkled and mixed with the fiber aggregate 7 in this way,
If the surface material 8 is previously bonded to the lower surface side of the fiber aggregate 7, the powder 4 scattered from the upper surface side to the fiber aggregate 7 passes through the fiber aggregate 7 and forms the fiber aggregate 7 and the surface material 8. It is possible to prevent the fiber aggregate 7 and the surface material 8 from being hindered due to the fusion of the coating material 2 with the fiber 3 having the core-sheath structure. For this reason, the bonding of the fiber aggregate 7 and the surface material 8 is reliably achieved, and the powder 4 is prevented from moving to the space created between the fibers 3 and 6 due to the loosening of the surface material 8, Can be prevented.

Web-shaped (non-woven) fiber aggregate 7 in which fibers 3 having a core-sheath structure and fibers 6 having a large shape restoring force coexist.
A material whose fiber density changes in the thickness direction can be used. Then, the fiber aggregate 7 manufactured so that the fiber density changes in the thickness direction is arranged with the fiber density high side down and the fiber density low side up,
The powder 4 is sprayed from above onto the fiber aggregate 7 to
In order to disperse and mix the powder 4 inside,
Since the upper part of the fiber aggregate 7 has a low fiber density and is coarse and the gap between the fibers is large, the powder 4 is favorably introduced into the fiber aggregate 7 and dispersed, and the lower part of the fiber aggregate 7 is Since the fiber density is high and dense and the gap between the fibers is small, the powder 4 does not locally accumulate under the fiber aggregate 7 and the powder 4 is uniformly dispersed in the fiber aggregate 7. What can be mixed.

The change in fiber density is, for example, 0.5 g / cm
It can be varied between ³ and 0.01 g / cm ³ . The fiber aggregate 7 in which the fiber density changes in the thickness direction can be manufactured, for example, as follows. That is, a web in which fibers 3 having a core-sheath structure and fibers 6 having a large shape restoring force are mixed is sandwiched between two plates, and one plate is heated at a temperature of, for example, about 150 ° C. and the other plate is not heated. And 0.35
By applying a pressure of about 1.0 g / cm ² , the fibers 3 and 6 are fused with the coating material 2 of the core-sheath structure fiber 3 in the fiber aggregate 7 on the heated plate side. The fiber density is higher and the fiber density on the unheated plate side is lower. Thus, the fiber aggregate 7 whose fiber density changes in the thickness direction can be manufactured.

The sound absorbing material B shown in FIG. 4 is obtained by laminating the sound absorbing material A obtained as shown in FIG. 3 with a porous material 9 such as glass wool, rock wool, foamed polyurethane, felt, nonwoven fabric, paper and the like. is there. The porous material 7 which has excellent sound absorption characteristics in the high frequency range but has low sound absorption characteristics in the low frequency range,
By laminating the above-mentioned sound absorbing material A having high sound absorbing characteristics in a low frequency range, it is possible to obtain a sound absorbing material B having excellent sound absorbing characteristics from a low frequency range to a high frequency range. Further, by laminating and integrating the porous material 9 in this manner, the mechanical strength of the sound absorbing material B can be increased. Further, the porous material 9 acts as a back air layer so that the low frequency band can be obtained. Can be further improved. Here, even if the sound absorbing material A and the porous material 9 are laminated and integrated by bonding with an adhesive or the like,
Any of them may be simply superimposed and laminated. The sound absorbing material B can be formed by laminating the sound absorbing material A without the surface material 8 obtained in FIG. 1 instead of the sound absorbing material A with the surface material 8 obtained in FIG.

[0030]

Next, the present invention will be described specifically with reference to examples. (Example 1) "Melty <4080" manufactured by Unitika Ltd., whose core material is polyester (melting point 150 ° C.) and coating material is low melting point polyester (melting point 110 ° C.) as the core-sheath structure fiber.
> ”(Fiber diameter 4 denier, average length 51 mm)
As a fiber having a large shape restoring force, a polyester fiber "Conju Crimped Wire <H38F>" manufactured by Unitika Ltd. (28.6% by weight of a polyester fiber having a fiber diameter of 6 denier and an average length of 51 mm, a fiber diameter of 13 denier and an average length of 13 mm) Sa51
mm of 72.4% by weight of polyester fiber), 30% by weight of fibers having a core-sheath structure and 70% by weight of fibers having a large shape restoring force are collected and accumulated, so that the areal density is 800 g. / M ² of a web-like fiber aggregate was formed. A talc powder having an average particle diameter of 20 μm was evenly sprayed on the fiber aggregate at a spray amount of 6500 g / m ² , and further mechanically vibrated to drop the talc powder into the fiber aggregate. Next, while pressing the mixture of the fiber aggregate and the talc powder to a thickness of 30 mm,
By performing a heat treatment at 50 ° C. for 30 minutes, a sound absorbing material having a thickness of 30 mm as shown in FIG. 1 was obtained.

Example 2 The upper and lower surfaces of a mixture of a fiber aggregate and talc powder prepared in the same manner as in Example 1 were coated on a polyester nonwoven fabric (“Melty <40” manufactured by Unitika Co., Ltd.).
80>"(fiber diameter 1.5 denier, average length 50mm)
Has a surface density of 70 g produced by hot roll treatment at 114 ° C.
/ M ² ), and heat-treating at 150 ° C. for 30 minutes while applying pressure to a thickness of 30 mm to obtain a 30 mm thick sound absorbing material covered with the surface material as shown in FIG. Wood was obtained.

Example 3 A fiber having the same core-sheath structure as in Example 1 was mixed at a ratio of 30% by weight, and a fiber having a large shape restoring force as in Example 1 was mixed at a ratio of 70% by weight and accumulated. A web-like fiber aggregate having a density of 100 g / m ² was formed. A talc powder having an average particle diameter of 20 μm was evenly sprayed on the fiber aggregate at a spray amount of 1000 g / m ² , and further mechanically vibrated to drop the talc powder into the fiber aggregate. Upper and lower surfaces of the mixture of the fiber aggregate and the talc powder are sandwiched between surface materials made of the same polyester nonwoven fabric as in Example 2, and the mixture is heated at 150 ° C. for 30 minutes while being pressed to a thickness of 3 mm. Thus, a 3 mm thick sound absorbing material having the structure shown in FIG. 3 was obtained. Then, this sound absorbing material is made of open-cell foamed polyurethane (density 16k).
(g / m ³ , thickness 30 mm) to obtain a sound absorbing material having a total thickness of 33 mm as shown in FIG.

(Example 4) By mixing and accumulating 30% by weight of fibers having the same core-sheath structure as in Example 1 and 70% by weight of fibers having a large shape restoring force as in Example 1, the surface area is increased. A web-like fiber aggregate having a density of 100 g / m ² was formed. Shirasu balloon powder having an average particle diameter of 200 μm was evenly sprayed on the fiber aggregate at a spraying amount of 500 g / m ² , and further mechanically vibrated to drop the Shirasu balloon powder into the fiber aggregate. . The upper and lower surfaces of the mixture of the fiber aggregate and the shirasu balloon powder are sandwiched between surface materials made of the same polyester non-woven fabric as in Example 2, and pressed at 150 ° C. while pressing to a thickness of 5 mm.
By heating for 0 minutes, the thickness of the structure of FIG.
m of the sound absorbing material was obtained. Then, this sound absorbing material was made of the same foamed polyurethane as in Example 3 (density: 16 kg / m ³ , thickness: 30 m).
m), a sound absorbing material with a total thickness of 35 mm as shown in FIG. 4 was obtained.

(Example 5) The fibers having the same core-sheath structure as in Example 1 were mixed at a ratio of 30% by weight and the fibers having the same shape restoring force as in Example 1 at a ratio of 70% by weight to be accumulated. A web having a density of 100 g / m ² was formed. A surface material made of the same polyester non-woven fabric as in Example 2 was placed on one side of this web, sandwiched between two metal plates, and pressed with a pressure of 0.55 kg / cm ² to form a metal plate on the side of the surface material. Is heated at a temperature of 150 ° C. for 1 minute to bond the surface material to one side and change the fiber density in the thickness direction so that the fiber density on the side to which the surface material is bonded is high and the fiber density on the other side is low. A fiber assembly material was produced. This fiber aggregate is arranged such that the surface material is on the lower side, and talc powder having an average particle diameter of 20 μm is evenly sprayed on the fiber aggregate at a spray amount of 1000 g / m ² and further mechanically vibrated. Then, the talc powder was dropped into the fiber aggregate. Further, the same surface material as in Example 2 was overlaid on the upper surface of the fiber aggregate, and was heated at 150 ° C. for 30 minutes while being pressed so as to have a thickness of 3 mm, whereby the sound absorbing material having the structure of FIG. Obtained.

Comparative Example 1 An open-cell foamed polyurethane (density: 16 kg / m ³ ) having a thickness of 30 mm was directly used as a sound absorbing material. Comparative Example 2 A layer having a bulk density of 0.5 g / cm ³ of talc powder (average particle size: 20 μm) having a thickness of 30 mm was placed between ^two polyester nonwoven fabrics (“Elves” manufactured by Unitika Ltd .; 50 g / m ² ). To obtain a sound absorbing material.

Comparative Example ³ A layer having a bulk density of 0.2 g / cm ³ of shirasu balloon powder (average particle size: 200 μm) between ^two polyester nonwoven fabrics (“Elves” manufactured by Unitika Ltd .; 50 g / m ² ). Was sandwiched with a thickness of 30 mm to obtain a sound absorbing material. (Comparative Example 4) "Melty <6080" manufactured by Unitika Co., Ltd., whose core material is polyester (melting point 150 ° C.) and coating material is low melting point polyethylene (melting point 115 ° C.)
> ”(2 denier fiber diameter, 51 mm average length)
This was integrated to form a web having an areal density of 100 g / m ² . A talc powder having an average particle diameter of 20 μm
The talc powder was evenly sprayed at a spraying rate of 000 g / m ² and further mechanically vibrated so that the talc powder was dropped into the web. Both upper and lower surfaces of the mixture of the web and the talc powder are sandwiched between surface materials made of a polyester nonwoven fabric (“Elves” manufactured by Unitika Ltd .; 50 g / m ² ), and pressed at 150 ° C. to a thickness of 3 mm. For 30 minutes to obtain a sound absorbing material having a thickness of 3 mm.

The sound absorbing properties of each of the sound absorbing materials obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were measured according to JIS A 1405.
The measurement was carried out based on "Method of measuring normal incidence sound absorption coefficient of building material by pipe method". The results are shown in FIGS. 5, 6, and 7. As shown in FIGS. 5, 6, and 7, all of Examples 1 to 4 show superior sound absorption characteristics in a low frequency range as compared with that of Comparative Example 1 which is a porous sound absorbing material. . In Comparative Examples 2 and 3, since the sound-absorbing material was composed only of the powder, the sound-absorbing characteristics showed a sharp peak at a specific frequency, and in Comparative Example 2 particularly, the sound-absorbing peak frequency was particularly low. Although the sound absorption coefficient is high, the width of the frequency to be absorbed is extremely narrow. On the other hand, in the sound absorbing materials of Examples 1 and 2, the same talc powder as that of Comparative Example 2 was used. However, although the frequency of the sound absorbing peak was increased, the sound absorbing characteristics extended over a wide frequency range. Further, the same can be said for Examples 3 and 4, and the sound absorption coefficient is also significantly improved. Further, Examples 1 and 2 weigh about 7 kg / m ² , while Comparative Example 2 using talc powder also weighs 30 m / m ^2.
It is about 15 kg / m ^{2 in} thickness m. Example 3
In No. 4 and No. 4, excellent sound absorbing properties were exhibited at a thickness of about 3 mm to 5 mm in combination with the foamed polyurethane, and a great reduction in weight was achieved, and a significant improvement in sound absorbing properties was recognized. In particular, Example 4 is about 0.7 k
g / m ² , and can be greatly reduced in weight as compared with Examples 1, 2 and 3. Comparative Examples 2 and 3
In Nos. 4 and 4, the powder is only sandwiched between polyester non-woven fabrics, so that the powder is biased or scattered when tilted or shaken. And stable characteristics were obtained.

A sample having a length of 10 cm, a width of 10 cm and a thickness of 3 mm was prepared from the sound absorbing materials of Example 5 and Comparative Example 4 and subjected to vibration for 5 minutes by a reciprocating shaker in parallel with the surface direction of the sample. Light was transmitted through each sample before and after the quake, and the transmitted light was photographed to observe the movement of the powder. FIG. 6 shows an image of the photographed image processed by a computer to express gradations of gradation in a stepwise manner. In FIG. 6, a dark portion is a portion with a large amount of powder, and a thin portion is a portion with a small amount of powder. In Example 5, since the powder particles were uniformly dispersed inside the web and the fibers and the fibers, and the fibers and the powder were effectively bonded, almost no movement of the powder inside was observed. In the case of No. 4, the dispersibility of the powder inside the web is poor, and the local presence of the powder hinders the fiber-fiber bonding. In addition, the effective bonding between the fiber and the powder is not sufficiently formed. It can be seen that the powder has moved considerably after a minute of shaking.

As described above, the sound-absorbing materials of the respective embodiments show good sound-absorbing characteristics even in the low-frequency range with respect to the conventional sound-absorbing materials, and are unlikely to cause performance deterioration due to powder spillage, unevenness and the like. Was something.

[0040]

As described above, the sound-absorbing material according to claim 1 of the present invention comprises a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material. Powder is mixed with a fiber aggregate in which fibers having a greater shape restoring force than the fibers of the structure coexist, and the fibers are fused with at least a part of the fibers and the fibers and the powder by the coating material of the core-sheath structure fibers. It is characterized by the fact that the powder can be prevented from moving by fusing the powder to the fiber. Can be prevented, and a sound-absorbing material having a high bulk can be obtained by a fiber having a large shape restoring force, and the sound absorbing characteristics can be prevented from deteriorating due to a decrease in the bulk. .

The sound-absorbing material according to claim 2 of the present invention has a core-sheath structure fiber in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a shape-recovery structure obtained from the core-sheath structure fiber. Powder is mixed with fiber aggregate that coexists with strong fibers,
At least a part of the fiber and the fiber and the powder are fusion-bonded to the fiber by the sheath material of the core-sheath structure, and the surface material is bonded to the surface of the fiber aggregate. In addition, it is possible to prevent the movement of the powder by fusing the powder to the fiber, and to prevent the powder from falling off from between the fibers by closing the gap between the fibers with the surface material, Deterioration of the sound absorption characteristics due to the bias of the powder can be effectively prevented, and a sound absorbing material having a high bulkiness can be obtained by a fiber having a large shape restoring force, and the sound absorption characteristics deteriorate due to the decrease in the bulkiness. It can also prevent things.

According to the third aspect of the present invention, since talc is used as the powder, a high sound absorbing effect can be obtained particularly in a low frequency range. According to the fourth aspect of the present invention, since a shirasu balloon is used as the powder, it is possible to obtain a high sound absorbing effect particularly in a middle and low frequency range. According to the invention of claim 5, since the above-described sound absorbing material is laminated with a porous material, a sound absorbing material having high mechanical strength can be obtained by the reinforcing effect of the porous material. The sound absorbing material having the sound absorbing characteristics in a wide frequency range can be obtained by synergistic effects of the sound absorbing characteristics of the porous material and the powder and the effect of the back air layer of the porous material.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a sound-absorbing material, comprising: a core-sheath fiber in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material; By mixing powder with a fiber aggregate in which fibers having a larger shape restoring force coexist, and heating the mixture at a temperature equal to or higher than the melting temperature of the sheathing material of the core-sheath structure fiber, the fiber and the fiber and the powder are mixed. It is characterized in that at least a part and the fiber are bonded by fusion of the coating material, and the fiber and the fiber and the powder and the fiber are fused only by mixing and heating the powder to the fiber aggregate. The sound absorbing material can be manufactured in a simple process, and the fibers having a large shape restoring force can maintain the bulkiness of the fiber aggregate, facilitating the dispersion of the powder inside the fiber aggregate. And can be performed uniformly.

According to a seventh aspect of the present invention, there is provided a method for producing a sound-absorbing material, comprising: a core-sheath structure fiber in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material; The powder is mixed with a fiber aggregate in which fibers having a larger shape restoring force coexist, and a surface material is further laminated on the surface of the fiber aggregate,
By heating this at a temperature equal to or higher than the melting temperature of the core-sheath fiber coating material, at least a part of the fiber and the fiber and the powder are bonded to the fiber by fusing the coating material, and the fiber is bonded to the surface of the fiber aggregate. It is characterized by joining the surface material, and the powder is mixed with the fiber aggregate and the surface material is superimposed on the fiber aggregate only by heating, and the fiber and the fiber and the powder and the fiber, and further the fiber aggregate It is possible to produce a sound absorbing material in which the material and the surface material are fused by a simple process,
Moreover, the bulkiness of the fiber aggregate can be maintained by the fibers having a large shape restoring force, and the powder can be easily and uniformly dispersed in the fiber aggregate.

The method for producing a sound-absorbing material according to claim 8 of the present invention is characterized in that a core-sheath structure fiber in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, After adhering a surface material to one surface of a fiber aggregate in which fibers having a larger shape restoring force coexist, a powder is mixed into the fiber aggregate, and this is a melting temperature of a core-sheath structure fiber coating material. By heating at the above temperature, at least a part of the fiber and the fiber and the powder and the fiber is bonded by fusion of the coating material, when mixing the powder to the fiber aggregate It can prevent the powder from entering between the surface material and the fiber aggregate, improving the bonding between the surface material and the delicate integrated material, thereby reducing the space in which the powder can move. This makes it possible to more reliably prevent the dressing body from moving or biasing.

The ninth aspect of the present invention provides a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a fiber having a greater shape restoring force than the fiber having the core-sheath structure. The fiber aggregate in which the fiber density changes in the thickness direction was prepared, and the powder was mixed with the fiber aggregate. When dispersing and mixing the powder in the fiber aggregate by spraying the powder from above with the low fiber density side up, the powder is placed on top of the fiber aggregate with a low fiber density and a large gap between the fibers. The body penetrates well and is dispersed, and the powder is uniformly dispersed in the fiber aggregate without the local accumulation of powder below the fiber aggregate where the fiber density is high and the gap between fibers is small. What can be mixed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 2 is an enlarged partially cutaway perspective view of a fiber having a core-sheath structure used in the present invention.

FIG. 3 is a schematic diagram showing an example of another embodiment of the present invention.

FIG. 4 is a schematic diagram showing an example of still another embodiment of the present invention.

FIG. 5 is a graph showing sound absorption characteristics (relation between sound absorption coefficient and frequency) of Examples 1 and 2 and Comparative Examples 1 and 2.

FIG. 6 is a graph showing sound absorption characteristics (relation between sound absorption coefficient and frequency) of Example 3 and Comparative Examples 1 and 2.

FIG. 7 is a graph showing sound absorption characteristics (relation between sound absorption coefficient and frequency) of Example 4 and Comparative Examples 1 and 3.

FIG. 8 is a diagram in which a photograph of transmitted light of a sound absorbing material sample is image-processed and printed by a computer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core material 2 Coating material 3 Core-sheath structure fiber 4 Powder 6 Fiber with large shape restoring force 7 Fiber aggregate 8 Surface material 9 Porous material

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Onishi 1048 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (9)

[Claims] 1. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a fiber having a greater shape restoring force than the fiber having the core-sheath structure coexist. A sound-absorbing material, wherein a powder is mixed with a material, and the fiber is fused to at least a part of the fiber, the fiber, and the powder by a covering material of a fiber having a core-sheath structure. 2. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material and a fiber having a greater shape restoring force than the fiber having the core-sheath structure coexist. The powder is mixed with the material, and at least a part of the fiber and the fiber and the fiber are fusion-bonded to the fiber by the core-sheath fiber covering material, and the surface material is bonded to the surface of the fiber aggregate. A sound absorbing material characterized in that: 3. The sound-absorbing material according to claim 1, wherein the powder is talc. 4. The sound-absorbing material according to claim 1, wherein the powder is a shirasu balloon. 5. The sound-absorbing material according to claim 1, wherein
A sound absorbing material characterized by being laminated with a porous material. 6. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material and a fiber having a greater shape restoring force than the fiber having the core-sheath structure coexist. By mixing powder into the material and heating it at a temperature equal to or higher than the melting temperature of the sheathing of the core-sheathed fiber, the fibers are bonded to at least a portion of the fiber and the powder by fusion of the sheathing. The method for producing a sound absorbing material according to claim 1, wherein: 7. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a fiber having a larger shape restoring force than the fiber having the core-sheath structure coexist. The powder is mixed with the material, and the surface material is further superimposed on the surface of the fiber aggregate material, and heated at a temperature equal to or higher than the melting temperature of the sheathing material of the core-sheath structure fiber, whereby the fiber and the fiber and the powder are mixed. The method for producing a sound absorbing material according to claim 2, wherein at least a part of the fiber is bonded to the fiber by fusing the coating material, and a surface material is bonded to a surface of the fiber aggregate. 8. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a fiber having a greater shape restoring force than the fiber having the core-sheath structure coexist. After adhering the surface material to one surface of the material, powder is mixed into the fiber aggregate, and heated at a temperature equal to or higher than the melting temperature of the sheathing material of the core-sheath structure fiber, whereby the fiber and the fiber and The method for producing a sound absorbing material according to claim 2, wherein at least a part of the powder and the fiber are joined by fusing the covering material. 9. A fiber assembly in which a fiber having a core-sheath structure in which the surface of a core material is coated with a coating material having a melting point lower than the melting point of the core material, and a fiber having a greater shape restoring force than the fiber having the core-sheath structure coexist. The method for producing a sound absorbing material according to any one of claims 6 to 8, wherein the material is produced as a material whose fiber density changes in the thickness direction, and powder is mixed with the fiber aggregate.