JPH0962268A - Sound absorbing material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the modulus of elasticity to assure an excellent sound absorbing performance, thereby prevent change in the performance with the lapse of time by adhering fiber structures having therein entangled fine fibers disposed between sound absorbing particles to the sound absorbing powder particles through binder layers on the surfaces of the particles. SOLUTION: The manufacturing method of a sound absorbing material 6 comprises: (a) a swelling step to prepare swelling particles by adding moisture 4 to water-absorbing resin particles 11 generating a sound absorbing action owing to oscillations of the particles own; (b) a mixing step to prepare powder mixture by mixing the swelling particles with powder composed of fiber structures 2 having therein entangled fibers; and (c) a drying step to make the structures 2 adhere to the particles 11 by drying the powder mixture. With the drying step, a strong adhering force is assured in the adhering part between the binder layer and the structures 2.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sound absorbing material and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a sound absorbing material is an interior material such as a listening room used for improving acoustic characteristics,
Filling material to improve sound insulation of walls, floors, ceilings, etc.
It is used for internal attachment of sound-absorbing ducts and sound-proof covers for devices that generate noise. Such conventional sound absorbing material utilizes the porosity of materials such as urethane foam, glass wool, rock wool, and ceramic foam. Sound-absorbing materials using these materials are generally called porous sound-absorbing materials, and sound waves and bubble wall surfaces are transmitted during the propagation of sound waves through the communicating bubbles and holes in the porous sound-absorbing material. The sound wave energy is absorbed by the porous sound absorbing material due to the action of viscous friction with the sound absorbing material.

Generally, a porous sound absorbing material has a low sound absorption coefficient for sound waves in a low frequency range, but a thick sound absorbing material can increase a sound absorption coefficient in a low frequency range. However,
If the thickness is increased, the volume of the sound absorbing material becomes large and the space becomes narrow, or there is a problem in building construction such that the sound absorbing material cannot be thickly filled because the actual building space is narrow. Further, even if such a problem in building construction can be overcome, the effect of increasing the sound absorption coefficient in the low frequency region is not so large in many cases, and therefore improvement of the sound absorbing material is required.

As an example of such an improvement, the applicant of the present invention has proposed a sound absorbing material containing powder having a large sound absorbing coefficient in a low frequency range even if it is thin in Japanese Patent Laid-Open No. 6184/1993. This sound absorbing material utilizes a phenomenon that specific powder particles vibrate in a low frequency range. Further, the present applicant has proposed a sound absorbing material in which a sound absorbing powder is mixed with a fiber structure having a structure in which fine fibers are entangled with each other, in Japanese Patent Laid-Open No. 5-173577. In this sound absorbing material, because the structure in which fine fibers are entangled with each other, a fiber structure that acts as a flexible spring is placed between the contact points of the sound absorbing powder particles, which reduces the elastic modulus of the powder layer. Thus, the effect that the sound absorption frequency can be further lowered is obtained, but it is desired to further improve the physical properties.

[0005]

The problem to be solved by the present invention is to provide a sound absorbing material which effectively reduces the elastic modulus, obtains an excellent sound absorbing action in the low sound range, and does not change its sound absorbing performance with time. The task is to do. Another problem to be solved by the present invention is to effectively reduce the elastic modulus, obtain an excellent sound absorbing effect in the low sound range, and easily industrially manufacture a sound absorbing material that does not change its sound absorbing performance with time. Is an issue.

[0006]

Means for Solving the Problems The present inventor has studied improvement of a sound absorbing material, and found that in a sound absorbing material in which a sound absorbing powder and a fiber structure having a structure in which fine fibers are entangled are mixed, (1) When the mixing is insufficient, the elastic modulus may not decrease so much that the sound absorption frequency is further lowered, and (2)
Since it is desired that sufficient sound absorption performance in the low frequency range does not change over time, if the fiber structure has a structure in which it is adhered to the sound absorbing powder particles by a binder, it is possible to eliminate the change over time in sound absorption performance. I obtained the knowledge that

Based on such knowledge, a method of adhering the fiber structure to the sound absorbing powder particles with a binder was investigated and studied,
A method of directly adhering a binder such as phenol or vinyl acetate to the powder using a spray, and then mixing the fibrous structure, or a method using a mechanochemical reaction using a special device such as Ongmill. Etc. However, the former has a problem that since the powder particles and the fibrous structure are not sufficiently adhered to each other due to the granulation of the powder particles, the elastic modulus is less decreased, and the sound absorption frequency is not sufficiently lowered. , It became clear that the latter has a problem that industrial production is difficult because it requires a small amount of batch processing.

The inventor of the present invention has made extensive studies to overcome the above problems and further improve the sound absorbing material, and arrived at the present invention. That is, the first sound absorbing material of the present invention has a structure in which fine particles are entwined with sound absorbing powder particles made of water absorbing resin particles that exhibit a sound absorbing effect by vibration of the particles themselves. A sound-absorbing material including a fibrous structure interposed therebetween, wherein the fibrous structure is adhered to the sound-absorbing powder particles by a binder layer composed of a surface layer portion of the sound-absorbing powder particles. And

The second sound absorbing material of the present invention is a fiber having a structure in which fine particles are entangled with sound absorbing powder particles that exhibit a sound absorbing effect by vibration of the particles themselves, and are present between the sound absorbing powder particles. A sound-absorbing material including a structure and a binder made of a water-absorbent resin, wherein the fibrous structure is bonded to the sound-absorbing powder particles by the binder.

A third sound absorbing material of the present invention is the above-mentioned second sound absorbing material, wherein the binder coats the surface of the sound absorbing powder particles with the water absorbing resin in a film form. A fourth sound absorbing material of the present invention is the second sound absorbing material, wherein the binder is water absorbing resin particles made of the water absorbing resin. The method for producing a sound absorbing material of the present invention is a swelling step of adding water to a sound absorbing powder particle composed of water absorbing resin particles that exhibit a sound absorbing function by vibrating the particle itself to expand it to obtain a swollen particle, and a fine fiber. A step of mixing a powder composed of a fiber structure having an entangled structure and the swollen particles to obtain a mixed powder, and drying the mixed powder to convert the fiber structure into the water absorbent resin particles. And a drying step of adhering.

Another method for producing a sound absorbing material of the present invention is to form a film-like coating layer made of a water-absorbent resin on the surface of a sound absorbing powder particle that exhibits a sound absorbing action by vibrating the particle itself to form the coated particle. Obtaining coating step, swelling step of adding water to the coated particles to expand to obtain swollen particles, and mixing powder with the swollen particles and powder consisting of a fiber structure having a structure in which fine fibers are entangled with each other A mixing step of obtaining a body and a drying step of drying the mixed powder to adhere the fibrous structure to the sound absorbing powder particles through the coating layer are included.

Yet another method for manufacturing a sound absorbing material according to the present invention is as follows:
A preparatory step of adhering water-absorbent resin particles to the surface of sound-absorbing powder particles that exhibit a sound-absorbing effect by vibration of the particles themselves, and obtaining adhesive particles by swelling by adding water to the adhesive particles and expanding them to obtain swollen particles. A mixing step of obtaining a mixed powder by mixing a powder composed of a fiber structure having a structure in which fine fibers are entangled with each other and the swollen particles; and the water-absorbent resin particles by drying the mixed powder. And a step of adhering the fibrous structure to the sound absorbing powder particles via a drying step.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The sound absorbing material contains sound absorbing powder particles and a fiber structure which will be described in detail below. Sound Absorbing Powder Particles The sound absorbing powder particles may be of any type as long as they are sound absorbing powder particles that exhibit a sound absorbing action by vibrating the particles themselves. The sound absorbing powder particles usually have a particle size of 0.1 to 100.
The powder is 0 μm and has a bulk density of 0.1 to 1.5 g / cm ³ or less.

Examples of such sound absorbing powder particles include inorganic sound absorbing powder particles made of powder particles of silica, mica, talc, vermiculite and the like. Further, the sound absorbing powder particles are not limited to the inorganic substance, and may be organic sound absorbing powder particles. These sound absorbing powder particles may be used alone or in combination of two or more as required. Among them, the sound absorbing powder particles are gold mica (average particle size: 40 μm, bulk density: about 0.4 g / cm ³ ), wet silica (average particle size:
7 to 150 μm, bulk density: about 0.1 to 0.3 g / cm
³ ), spherical silica (average particle size: 3 to 28 μm, bulk density: about 0.3 to 0.9 g / cm ³ ), talc (average particle size: 1.5 to 9.4 μm, bulk density: about 0. 3 to 0.5
g / cm ³ ), acrylic fine powder (average particle size: 1-2 μ)
m, bulk density: about 0.3 g / cm ³ ), calcium silicate powder (average particle size: 20 to 30 μm, bulk density: about 0.1 g / cm ³ ), barlite powder (average particle size: 1)
00-150 μm, bulk density: about 0.1-0.2 g / c
m ³ ), fluororesin powder (average particle size: 5 to 25 μm,
Bulk density: about 0.4 to 0.5 g / cm ³ ), bainite (average particle size: 0.3 to 3.5 μm, bulk density: about 0.5 to 0.8 g / cm ³ ), shirasu balloon ( Average particle size: 30 to 50 μm, bulk density: about 0.2 to 0.3 g
/ Cm ³ ), fused silica (average particle size: 5 to 32 μm,
Bulk density: about 0.5 to 0.8 g / cm ³ ), silicon carbide powder (average particle size: 0.4 to 5.0 μm, bulk density: about 0.6 to 1.1 g / cm ³ ), nylon Powder (average particle size: 5 to 250 μm, bulk density: about 0.3 to 0.5)
g / cm ³ ), acrylic powder (average particle size: about 45μ)
m, bulk density: about 0.6 to 0.7 g / cm ³ ), carbon fiber powder (average particle diameter: 14 to 18 μm, fiber length: 100)
~ 200 μm, bulk density: about 0.5-0.6 g / c
m ³ ), titanium dioxide powder (average particle size: 0.1 to 0.
25 μm, bulk density: about 0.5 to 0.7 g / cm ³ ),
Calcium carbonate powder (average particle size: 3 to 30 μm, bulk density: about 0.6 to 1.0 g / cm ³ ), vinyl chloride resin powder (average particle size: about 130 μm, bulk density: about 0.5)
g / cm ³ ), barium ferrite magnetic powder (average particle size:
1.8 to 2.2 μm, bulk density: about 1.5 g / c
m ³ ), silicon powder (average particle size: 0.3 to 0.
7 μm, bulk density: about 0.2 to 0.3 g / cm ³ ) and the like are preferable.

The sound-absorbing powder particles may be sound-absorbing powder particles made of water-absorbent resin particles that exhibit a sound-absorbing effect by vibrating the particles themselves. Examples of the water-absorbent resin constituting such water-absorbent resin particles include starch-based, cellulose-based, hyaluronic acid-based, polyvinyl alcohol-based, acrylic-based, acrylamide-based, Poval-based,
Water-absorbent resins such as polyoxyethylene-based and maleic anhydride-based can be mentioned. These water absorbent resins may be used alone or in combination of two or more as required. Among them, when the water-absorbent resin is one selected from polyacrylic acid-based resin that is an acrylic resin and isobutylene-maleic anhydride-based resin that is a maleic anhydride-based resin, the water-absorbent resin does not become a gel after absorbing water. It is preferable because it has a property of retaining the shape before water absorption. Fibrous structure The fibrous structure has a structure in which fine fibers are entangled with each other, and in the sound absorbing material, they are interposed between the sound absorbing powder particles.
In FIG. 8, the fine fibers 21 are intertwined with each other to form the fiber structure 2.
Is formed.

The fine fibers constituting the fiber structure include
Whiskers such as silicon carbide, silicon nitride, zinc oxide, potassium titanate, zonotolite; wollastonite,
Mineral fibers such as sepiolite and slag fiber can be used. As shown in FIG. 8, the fibrous structure has a structure in which individual fine fibers are aggregated. With such a structure, the fiber structure acts like a soft spring, effectively reducing the elastic modulus, and even if the sound absorbing material has the same thickness, excellent sound absorption in the lower range is achieved. The action can be obtained.

The average agglomerated particle diameter of the fiber structure is not particularly limited, but it is preferably 100 μm or less because adhesion to the sound absorbing powder particles is easy and detachment due to its own weight does not easily occur. The average fiber diameter of the fine fibers is not particularly limited, but is 0.1 to 10 μm, and the average fiber length of the fine fibers is not particularly limited, but if it is 1 to 50 μm, the spring of the fiber aggregated particles becomes flexible. preferable. First Sound Absorbing Material and Manufacturing Method Thereof As shown in FIG. 1, a sound absorbing powder particle made of water-absorbent resin particles 11 exhibiting a sound absorbing action by vibration of particles themselves, and a fine fiber 21. The structure in which the
And the fibrous structure 2 interposed between the sound absorbing powder particles. Further, this sound absorbing material is characterized in that the fibrous structure is bonded to the sound absorbing powder particles by a binder layer composed of a surface layer portion of the sound absorbing powder particles.

The mixing ratio of the sound absorbing powder particles composed of the water absorbing resin particles and the fiber structure is not particularly limited, but the mixing ratio [water absorbing resin particles: fiber structure] is 1: 4.
It is preferable for it to be 10: 1 (volume ratio) because the elastic modulus can be effectively reduced and the sound absorbing performance will be more excellent in the low sound range. The binder layer is composed of the surface layer portion of the water absorbent resin particles, and the polymer chain of the water absorbent resin in the surface layer portion of the water absorbent resin particles sandwiches the fiber structure, thereby acting as a binder layer and forming a fiber structure. The body comes to adhere to the sound absorbing powder particles composed of the water absorbing resin particles.

The fibrous structure forming the sound absorbing material acts like a soft spring, effectively reducing the elastic modulus, and exhibiting excellent sound absorbing performance in a lower sound range. Further, the binder layer is composed of the surface layer portion of the water-absorbent resin particles, whereby the fibrous structure is adhered to the water-absorbent resin particles. Does not fall off from the powdery particles, stable sound absorption performance is obtained over a long period of time, and the sound absorption performance does not change over time.

In the sound absorbing material, as shown in FIG. 1, the fibrous structure is interposed between the respective sound absorbing powder particles, which does not necessarily prevent direct contact between the sound absorbing powder particles. However, it is preferable that the sound absorbing powder particles do not come into direct contact with each other, because the elastic modulus is effectively reduced and excellent sound absorbing performance is exhibited in a lower sound range. The first sound absorbing material 6 is, for example, as shown in FIG. 5, swelling particles by adding water 4 to sound absorbing powder particles composed of water absorbing resin particles 11 that exhibit a sound absorbing action by vibration of the particles themselves and expanding the particles. And a swelling step of obtaining a mixed powder 5 by mixing a powder composed of a fiber structure 2 having a structure in which fine fibers are entangled with each other and the swollen particles, and drying the mixed powder. The fibrous structure 2 is replaced with the water absorbent resin particles 11
It can be obtained by a method for producing a sound absorbing material, which includes a drying step of adhering to the sound absorbing material. Hereinafter, a method for manufacturing this sound absorbing material will be described in detail.

The swelling step is a step of obtaining water-absorbent resin particles 11 by adding water 4 to the sound-absorbing powder particles and expanding them to obtain swollen particles. In the swelling step, the surface area of the water-absorbent resin particles increases, and the probability of contact between the particles increases when they are mixed with the fibrous structure. The swelling ratio (particle size ratio before and after swelling) of the water-absorbent resin particles is not particularly limited, but when it is at least twice the water-absorbent resin particles during drying, the surface area of the water-absorbent resin particles increases and the fiber This is preferable because the probability of contact between the two when they are mixed with the structure is improved and a large number of fiber structures can be bonded to the particle surface.

As a method of adding water to the water-absorbent resin particles and swelling them, water may be added by a usual method. For example, the water-absorbent resin particles and an appropriate amount of water are added to a reaction vessel and mechanically stirred. Methods and the like. The mixing step is a step of mixing the powder made of the fiber structure 2 having a structure in which fine fibers are entangled with each other and the swollen particles to obtain the mixed powder 5. In the mixing step, the adhesive force based on the liquid crosslinking force or the like acts between the water existing on the surface of the water absorbent resin particles and the fiber structure, and the fiber structure adheres to the surface of the water absorbent resin particles.

The compounding ratio of the water absorbent resin particles (dry state) and the fiber structure is not particularly limited, but the compounding ratio [water absorbent resin particles (dry state): fiber structure] is 1: 4.
It is preferable for it to be 10: 1 (volume ratio) because the elastic modulus can be effectively reduced and the sound absorbing performance will be more excellent in the low sound range. Examples of the mixing device used in the mixing step include a container rotary type mixer, a mechanical stirring type mixer, and an airflow stirring type mixer.

The drying step is a step of adhering the fibrous structure 2 to the water absorbent resin particles 11 by drying the mixed powder. By the drying step, the water-absorbent resin particles shrink, and the polymer chain of the water-absorbent resin constituting the water-absorbent resin particles is a fine fiber in the adhesion portion between the binder layer formed of the surface portions of the water-absorbent resin particles and the fiber structure. Since the adhesive is sandwiched, a strong adhesive force is obtained, and the sound absorbing performance does not change with time. Further, by drying, the surface area of the water-absorbent resin particles is reduced, the proportion of the fiber structure occupying the surface of the water-absorbent resin particles is increased, the elastic modulus is effectively reduced, and excellent in the bass range. Sound absorption performance is obtained.

The drying temperature of the mixed powder is not particularly limited, but is preferably 80 to 120 ° C. because the evaporation of water is promoted. The drying time is not particularly limited. Furthermore, examples of the drying device used in the drying step include a hot air drying device and a high frequency drying device. Second to fourth sound absorbing materials and method for producing the same The second sound absorbing material has a structure in which fine particles are entangled with sound absorbing powder particles that exhibit a sound absorbing action by vibration of the particles themselves. A sound absorbing material comprising a fibrous structure interposed between the fibrous structure and a binder made of a water absorbent resin, wherein the fibrous structure is bonded to the sound absorbing powder particles by the binder.

As shown in FIG. 3, the third sound absorbing material is the same as the second sound absorbing material, but the binder is sound absorbing powder particles 3
The water absorbent resin 12 is coated in a film shape on the surface of the. As shown in FIG. 4, the fourth sound absorbing material is the second sound absorbing material.
In the sound absorbing material, the binder is the water absorbing resin particles 11 made of a water absorbing resin.

Hereinafter, the second to fourth sound absorbing materials will be described in detail. The binder contained in the sound absorbing material is made of a water absorbing resin. As the water absorbent resin, the water absorbent resin described in the section of the sound absorbing powder particles can be used as it is. The binder may be a film of water-absorbent resin coated on the surface of sound-absorbing powder particles, or may be water-absorbent resin particles made of a water-absorbent resin.

The mixing ratio of the sound absorbing powder particles and the binder made of a water absorbing resin is not particularly limited,
Mixing ratio [sound absorbing powder particles: binder] is 100: 1
The ratio of 10 to 10 (weight ratio) is preferable because the fiber structure can be firmly bonded. The mixing ratio of the sound absorbing powder particles and the fiber structure is not particularly limited, but the mixing ratio [sound absorbing powder particles: fiber structure] is 1: 4.
It is preferable for it to be 10: 1 (volume ratio) because the elastic modulus can be effectively reduced and the sound absorbing performance will be more excellent in the low sound range.

In the second to fourth sound absorbing materials, the binder is made of a water absorbing resin, and since the polymer chains of the water absorbing resin sandwich the fiber structure, the fiber structure is bonded to the sound absorbing powder particles. Become so. As shown in FIG. 3, the binder may be a film in which the surface of the sound absorbing powder particles 3 is coated with the water absorbent resin 12, and the binder is
As shown in FIG. 4, water-absorbent resin particles 11 made of a water-absorbent resin may be used.

The fibrous structure constituting the sound absorbing material acts like a soft spring, effectively reducing the elastic modulus, and exhibiting excellent sound absorbing performance in a lower sound range. Furthermore, the binder is made of a water-absorbent resin, and since the fibrous structure is bonded to the sound absorbing powder particles by this, the fibrous structure does not fall off from the sound absorbing powder particles even if time passes, Stable sound absorption performance is obtained over a long period of time, and the sound absorption performance does not change over time.

In the second to fourth sound absorbing materials, as in the first sound absorbing material, the fibrous structure is interposed between the respective sound absorbing powder particles (for example, FIGS. 3 and 4). , Does not necessarily prevent the sound absorbing powder particles from directly contacting each other, but if the sound absorbing powder particles do not directly contact each other,
It is preferable in that the elastic modulus is effectively reduced and excellent sound absorbing performance is exhibited in a lower range.

The third sound-absorbing material 61 is, for example, as shown in FIG. 6, a film-like coating layer made of a water-absorbent resin 12 on the surface of the sound-absorbing powder particles 3 exhibiting a sound-absorbing effect by vibration of the particles themselves. A powder comprising a fiber structure 2 having a structure in which fine fibers are entangled with each other, And a step of mixing the swollen particles to obtain a mixed powder 51, and drying the mixed powder 51 to bond the fibrous structure 2 to the sound absorbing powder particles 3 through the coating layer. It can be obtained by another method for producing a sound absorbing material, which includes a drying step.

Hereinafter, another method of manufacturing the sound absorbing material will be described in detail. In the coating step, the water-absorbent resin 1 is applied to the surface of the sound-absorbing powder particles 3 that exhibit a sound-absorbing effect by vibrating the particles themselves.
In this step, a film-shaped coating layer composed of 2 is formed to obtain coated particles. As a method for forming such a film-like coating layer, a water-absorbent resin may be coated on the sound absorbing powder particles by a usual method, and examples thereof include fluidized bed coating.

A water absorbent resin used for coating,
Regarding the blending ratio with the sound absorbing powder particles, the water absorbent resin is used as a binder, and the above blending ratio [sound absorbing powder particles: binder] may firmly bond the fiber structure. It is preferable because it is possible. The swelling process is
In this step, water 4 is added to the coated particles 7 and the particles are expanded to obtain swollen particles. In the swelling step, the surface area of the water-absorbent resin forming the coating layer is increased, and the contact probability between the two is improved during mixing with the fibrous structure.

The swelling ratio (particle size ratio before and after swelling) of the water-absorbent resin is not particularly limited, but if it is at least twice as large as the water-absorbent resin during drying, the surface area of the water-absorbent resin will increase.
This is preferable because the probability of contact between the two when they are mixed with the fibrous structure is improved and a large number of fibrous structures can be bonded to the particle surface. As a method of adding water to the coated particles to swell, water may be added by a usual method, for example, by adding the coated particles and an appropriate amount of water to a reaction vessel,
Examples thereof include a method of mechanically stirring.

The mixing step is a step of obtaining a mixed powder 51 by mixing the powder consisting of the fiber structure 2 having a structure in which fine fibers are entangled with each other and the swollen particles. In the mixing step, the adhesive force based on the liquid crosslinking force acts between the water present on the surface of the water absorbent resin forming the coating layer and the fiber structure, and the fiber structure adheres to the surface of the water absorbent resin. To do.

With respect to the mixing ratio of the sound absorbing powder particles and the fiber structure, when the above mixing ratio [sound absorbing powder particles: fiber structure], the elastic modulus can be effectively reduced, It is preferable because the sound absorption performance is further excellent in the low sound range. Examples of the mixing device used in the mixing step include a container rotary type mixer, a mechanical stirring type mixer, and an airflow stirring type mixer.

The drying step is a step of adhering the fiber structure 2 to the sound absorbing powder particles 3 through the coating layer by drying the mixed powder 51. By the drying process, the water-absorbent resin forming the coating layer shrinks, and the polymer chains of the water-absorbent resin sandwich the fine fibers in the area where the water-absorbent resin and the fibrous structure are attached, resulting in a strong adhesive force. , The sound absorption performance does not change with time. Further, by drying, the surface area of the water absorbent resin is reduced,
The ratio of the fiber structure occupying the surface of the water absorbent resin is increased, the elastic modulus is effectively reduced, and excellent sound absorbing performance is obtained in the low sound range.

The drying temperature of the mixed powder is not particularly limited, but 80 to 120 ° C. is preferable because evaporation of water is promoted. The drying time is not particularly limited. Furthermore, examples of the drying device used in the drying step include a hot air drying device and a high frequency drying device. Next, the fourth sound absorbing material 62 is, for example, as shown in FIG. 7, the water absorbing resin particles 1 on the surface of the sound absorbing powder particles 3 that exhibit a sound absorbing action by the vibration of the particles themselves.
1 a step of adhering 1 to obtain adhesive particles, a swelling step of adding water 4 to the adhesive particles to expand them to obtain swollen particles, and a powder composed of a fiber structure 2 having a structure in which fine fibers are entangled with each other. A mixing step of mixing the swollen particles to obtain the mixed powder 52, and drying the mixed powder 52 to cause the fibrous structure 2 to interpose the sound absorbing powder particles 3 through the water absorbent resin particles 11. And a drying step of adhering to the sound absorbing material.

Hereinafter, another method for manufacturing the sound absorbing material will be described in detail. The preparation step is a step of adhering the water-absorbent resin particles 11 to the surface of the sound-absorbing powder particles 3 that exhibit a sound-absorbing effect by vibrating the particles themselves to obtain adhesive particles. As a method for adhering the water-absorbent resin particles to the surface of the sound-absorbing powder particles, the water-absorbing resin particles may be adhered to the sound-absorbing powder particles by a usual method, for example, spraying the sound-absorbing powder particles. A method of adhering a binder using the mixture and then mixing the water-absorbent resin particles can be used.

Regarding the mixing ratio of the water-absorbent resin particles and the sound-absorbing powder particles, the water-absorbing resin particles are used as a binder, and the above-mentioned mixing ratio [sound-absorbing powder particles: binder] It is preferable because the fibrous structure can be firmly bonded. In the swelling process, the adhesive particles have a water content of 4
Is a step of adding and expanding to obtain swollen particles. In the swelling step, the surface area of the water-absorbent resin particles increases, and the probability of contact between the particles increases when they are mixed with the fibrous structure.

The swelling ratio (particle size ratio before and after swelling) of the water-absorbent resin particles is not particularly limited, but if the water-absorbent resin particles are at least twice the dry water-absorbent resin particles, the surface area of the water-absorbent resin particles will increase. However, it is preferable because the probability of contact between the fibrous structures during mixing with the fibrous structures is improved and a large number of fibrous structures can be bonded to the particle surfaces. As a method for adding water to the adhesive particles to allow them to swell, water may be added by a usual method, and examples thereof include a method of adding the adhesive particles and an appropriate amount of water to a reaction vessel and mechanically stirring the mixture.

The mixing step is a step of mixing the powder composed of the fiber structure 2 having a structure in which fine fibers are entangled with each other and the swollen particles to obtain the mixed powder 52. In the mixing step, the adhesive force based on the liquid crosslinking force acts between the water present on the surface of the water absorbent resin particles and the fiber structure, and the fiber structure adheres to the surface of the water absorbent resin. Regarding the mixing ratio of the sound-absorbing powder particles and the fiber structure, when the above-mentioned mixing ratio [sound-absorbing powder particles: fiber structure], the elastic modulus can be effectively reduced and in the low sound range. It is preferable because the sound absorbing performance is further excellent.

The mixing device used in the mixing step is
For example, a container rotary type mixer, a mechanical stirring type mixer, an air flow stirring type mixer and the like can be mentioned. The drying step is a step of adhering the fiber structure 2 to the sound absorbing powder particles 3 through the water absorbing resin particles 11 by drying the mixed powder 52. By the drying step, the water-absorbent resin particles shrink, and at the adhesion portion between the water-absorbent resin particles and the fibrous structure, the polymer chains of the water-absorbent resin forming the water-absorbent resin particles sandwich the fine fibers, resulting in a strong adhesion. The force is obtained, and the sound absorption performance does not change with time. Further, by drying, the surface area of the water-absorbent resin particles is reduced, the proportion of the fiber structure occupying the surface of the water-absorbent resin particles is increased, the elastic modulus is effectively reduced, and excellent in the bass range. A sound absorbing effect is obtained.

The drying temperature of the mixed powder is not particularly limited, but it is preferably 80 to 120 ° C. because the evaporation of water is promoted. The drying time is not particularly limited. Furthermore, examples of the drying device used in the drying step include a hot air drying device and a high frequency drying device. Any of the sound absorbing materials described above is generally filled in a box-shaped body having an opening, and the opening is sealed with a sound-transmitting polymer film, or a sound-transmitting polymer film or the like. It is used in a closed sheet form or the like.

[0046]

Embodiments of the present invention will be described below in detail.
Regarding the sound absorbing powder particles, the fiber structure, the kind of the water absorbent resin, the combination and the mixing ratio thereof, and the respective physical properties (for example, bulk density, particle diameter, fiber diameter, fiber length, etc.), It is not limited to the example. Example 1 As the water-absorbent resin particles 11, polyacrylic acid-based resin particles having a particle size of 70 to 140 μm and a bulk density of 870 kg / m ³ , and as the fiber structure 2, an average fiber diameter of 0.4 μm.
m, an average fiber length of 10 μm, and an average agglomerated particle diameter of 50 μm, a silicon carbide whisker agglomerated structure was prepared. Swelling particles were obtained by swelling 10 parts by weight of water-absorbent resin particles with 500 parts by weight of water. The swollen particles were mixed with 1.8 parts by weight of the fibrous structure to obtain mixed particles in which the fibrous structure was attached to the surfaces of the swollen particles. The mixed particles were dried under a drying condition of 120 ° C. for 5 hours, and the fiber structure was adhered to the surface of the water absorbent resin particles to obtain a sound absorbing material (according to the manufacturing method shown in FIG. 5).

An electron micrograph of the obtained sound absorbing material is shown in FIG. From FIG. 2, it can be seen that the entire surface of the particles of the sound absorbing material is covered with the silicon carbide whisker aggregate structure. That is, since the contact of the sound absorbing powder particles is almost completely replaced by the contact of the fibrous structure, the sound absorption frequency can be sufficiently lowered by the reduction of the elastic modulus. In addition, as a side effect, the present invention does not use any organic solvent or the like, and therefore, industrial production is easy.

[0048]

EFFECTS OF THE INVENTION The sound absorbing material of the present invention can effectively reduce the elastic modulus, obtain an excellent sound absorbing action in the low sound range, and eliminate the time-dependent change of the sound absorbing performance. The method for producing a sound absorbing material of the present invention is capable of effectively reducing the elastic modulus, obtaining an excellent sound absorbing effect in the low sound range, and industrially facilitating the sound absorbing material capable of eliminating the temporal change of the sound absorbing performance. Can be manufactured.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first sound absorbing material of the present invention.

FIG. 2 is an electron micrograph of the sound absorbing material obtained in Example 1.

FIG. 3 is a configuration diagram showing a third sound absorbing material of the present invention.

FIG. 4 is a configuration diagram showing a fourth sound absorbing material of the present invention.

FIG. 5 is a configuration diagram showing a method for manufacturing a sound absorbing material of the present invention.

FIG. 6 is a configuration diagram showing another method for manufacturing the sound absorbing material of the present invention.

FIG. 7 is a configuration diagram showing still another method for manufacturing the sound absorbing material of the present invention.

FIG. 8 is a configuration diagram showing a fiber structure.

[Explanation of symbols]

 11 Water-Absorbing Resin Particles 12 Water-Absorbing Resin 2 Fiber Structure 21 Fine Fibers 3 Sound Absorbing Powder Particles 4 Moisture 5 Mixed Powder 51 Mixed Powder 52 Mixed Powder 6 Sound Absorbing Material 61 Sound Absorbing Material 62 Sound Absorbing Material 7 Adhesive Particles 8 Coating particle

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 26, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

Examples of such sound absorbing powder particles include inorganic sound absorbing powder particles made of powder particles of silica, mica, talc, vermiculite and the like. Further, the sound absorbing powder particles are not limited to the inorganic substance, and may be organic sound absorbing powder particles. These sound absorbing powder particles may be used alone or in combination of two or more as required. Among them, the sound absorbing powder particles are gold mica (average particle size: 40 μm, bulk density: about 0.4 g / cm ³ ), wet silica (average particle size:
7 to 150 μm, bulk density: about 0.1 to 0.3 g / cm
³ ), spherical silica (average particle size: 3 to 28 μm, bulk density: about 0.3 to 0.9 g / cm ³ ), talc (average particle size: 1.5 to 9.4 μm, bulk density: about 0. 3 to 0.5
g / cm ³ ), acrylic fine powder (average particle size: 1-2 μ)
m, a bulk density of about 0.3g / cm ^3), calcium powder (average particle size silica: 20 to 30 [mu] m, bulk density: about 0.1g / cm ^3), Pas Raito powder (average particle size: 1
00-150 μm, bulk density: about 0.1-0.2 g / c
m ³ ), fluororesin powder (average particle size: 5 to 25 μm,
Bulk density: about 0.4~0.5g / cm ^3), base down Tokyo <br/> preparative (average particle size: 0.3～3.5Myuemu, bulk density: about 0.5~0.8g / cm ³ ), Shirasu balloon (average particle size: 30 to 50 μm, bulk density: about 0.2 to 0.3 g)
/ Cm ³ ), fused silica (average particle size: 5 to 32 μm,
Bulk density: about 0.5 to 0.8 g / cm ³ ), silicon carbide powder (average particle size: 0.4 to 5.0 μm, bulk density: about 0.6 to 1.1 g / cm ³ ), nylon Powder (average particle size: 5 to 250 μm, bulk density: about 0.3 to 0.5)
g / cm ³ ), acrylic powder (average particle size: about 45μ)
m, bulk density: about 0.6 to 0.7 g / cm ³ ), carbon fiber powder (average particle diameter: 14 to 18 μm, fiber length: 100)
~ 200 μm, bulk density: about 0.5-0.6 g / c
m ³ ), titanium dioxide powder (average particle size: 0.1 to 0.
25 μm, bulk density: about 0.5 to 0.7 g / cm ³ ),
Calcium carbonate powder (average particle size: 3 to 30 μm, bulk density: about 0.6 to 1.0 g / cm ³ ), vinyl chloride resin powder (average particle size: about 130 μm, bulk density: about 0.5)
g / cm ³ ), barium ferrite magnetic powder (average particle size:
1.8 to 2.2 μm, bulk density: about 1.5 g / c
m ³ ), silicon powder (average particle size: 0.3 to 0.
7 μm, bulk density: about 0.2 to 0.3 g / cm ³ ) and the like are preferable.

Claims (7)

[Claims] 1. A fibrous structure having a structure in which fine particles are entangled with a sound-absorbing powder particle composed of water-absorbing resin particles that exhibit a sound-absorbing effect by vibration of the particle itself, and are interposed between the sound-absorbing powder particles. And a fibrous structure adhered to the sound absorbing powder particles by a binder layer composed of a surface layer portion of the sound absorbing powder particles. 2. From a water-absorbent resin, a sound-absorbing powder particle that exhibits a sound-absorbing effect by vibration of the particle itself, a fiber structure having a structure in which fine fibers are entangled with each other, and interposed between the sound-absorbing powder particles. A sound-absorbing material including the binder, wherein the fibrous structure is adhered to the sound-absorbing powder particles by the binder. 3. The sound absorbing material according to claim 2, wherein the binder is formed by coating the surface of the sound absorbing powder particles with the water absorbing resin in a film shape. 4. The sound absorbing material according to claim 2, wherein the binder is water absorbing resin particles made of the water absorbing resin. 5. A swelling step of adding water to a sound-absorbing powder particle composed of water-absorbent resin particles that exhibit a sound-absorbing effect by vibrating the particle itself to expand and obtain swollen particles, and a structure in which fine fibers are entangled with each other. A mixing step of mixing a powder composed of a fibrous structure and the swollen particles to obtain a mixed powder; and a drying step of adhering the fibrous structure to the water absorbent resin particles by drying the mixed powder. A method for manufacturing a sound absorbing material, including: 6. A coating step of forming a film-like coating layer made of a water-absorbent resin on the surface of a sound-absorbing powder particle which exhibits a sound-absorbing effect by vibration of the particle itself to obtain a coated particle, and a water content on the coated particle. A swelling step of adding and expanding to obtain swollen particles, a mixing step of mixing a powder composed of a fiber structure having a structure in which fine fibers are intertwined with the swollen particles to obtain a mixed powder, and the mixed powder And a drying step of adhering the fibrous structure to the sound absorbing powder particles through the coating layer by drying the body. 7. A preparatory step of adhering water-absorbent resin particles to the surface of sound-absorbing powder particles that exhibit a sound-absorbing effect by vibration of the particles themselves to obtain adhesive particles, and adding water to the adhesive particles to expand them. A swelling step of obtaining swollen particles, a mixing step of obtaining a mixed powder by mixing a powder composed of a fiber structure having a structure in which fine fibers are entangled with each other and the swollen particles, and drying the mixed powder And a drying step of adhering the fibrous structure to the sound absorbing powder particles via the water absorbing resin particles.