JPH09119177A - Sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sound absorbing material high in a sound absorbing rate in a low frequency area even with thin thickness and excellent in handling performance as material. SOLUTION: Sound absorbing material is provided with a porous material Al with a bulk density of 200-500kg/m<3> and a Young's modulus of 1.0×10<6> -1.0×10<8> N/m<2> and porous material B2 laminated on the surface of the porous material Al and having a bulk density of 100kg/m<3> or less and a Young' modulus of 1.0×10<3> -1.0×10<6> N/m<2> . The porous material Al side is made the incident side of sound wave, and the porous material B2 side is made the transmission side of this sound wave.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sound absorbing material.

[0002]

2. Description of the Related Art Conventionally, sound absorbing materials have been used for the following applications. Used as interior materials for listening rooms, musical instrument practice rooms, etc. It is used as a finishing interior material for controlling indoor reverberation time characteristics, reflection characteristics, and the like in a room where acoustic characteristics in the room are problematic.

Used as a filler for walls and ceilings. In rooms where sound insulation properties are required, a double panel structure is often employed to improve the sound insulation performance of walls and ceilings. The space between these panels is filled with a sound absorbing material and used to further improve the performance. In addition, it is used for sticking inside sound absorbing ducts and inside soundproof covers of equipment that generates noise.

Conventional sound absorbing materials used in these applications utilize the porosity of materials such as urethane foam and glass wool. The sound absorption mechanism is based on the fact that when sound waves enter into communicating bubbles or holes such as urethane foam or glass wool, the communicating bubbles or holes are open cells with a complicated cross-sectional shape. It is considered that the sound pressure is reduced by viscous friction or the like, and as a result, sound wave energy is absorbed in the sound absorbing material.

The sound absorption coefficient of the porous material increases as the frequency of the sound wave increases and as the thickness increases, but is small for the sound wave in the low frequency range (particularly 250 Hz or less). If the thickness of the porous material is increased, the sound absorption in the low frequency range can be increased. However, when a porous material is used as the interior material of a room, if the porous material is thick, there is a problem that the room becomes narrow. If the porous material is thick when used as an inner lining of a duct, there is a problem that the air passage is narrowed. Therefore, a method of increasing the thickness of the porous material to increase the sound absorption coefficient in a low frequency range is not an appropriate method.

From another point of view, the applicant of the present invention, as a sound absorbing material having a sufficient sound absorption coefficient in a low frequency range different from that of the porous material, is a powder having a sound absorbing effect on sound waves in a low frequency band. Have proposed a sound absorbing material utilizing the vibration (Japanese Patent Application No. 2-294220, Japanese Patent Application No. 4-120103, Japanese Patent Application No. 6-176295). Even with sound absorbing materials that use such powders, in order to obtain better sound absorbing performance in the low frequency range, it is necessary to thicken the powder layer as in the above case. When using a sound absorbing material utilizing the above, there is a problem that handleability as a material is deteriorated, and there is a performance deterioration due to spilling or uneven distribution of powder during use of such a sound absorbing material.

[0007] In order to improve these, the applicant of the present invention, in order to improve the handleability as a material, by laminating a porous material layer on the sound wave transmitting side of the sound absorbing powder layer, A sound-absorbing material having a significantly reduced layer thickness is proposed (Japanese Patent Application No. 6-257217). Further, the present applicant has proposed a powder holding sheet in which a powder having excellent sound absorbing characteristics is formed into a sheet shape. This powder holding sheet has a thin powder layer that can be cut and processed, has high handleability as a material, and does not show performance deterioration due to powder spills, uneven distribution, etc. The sound absorbing material has excellent sound absorbing characteristics against the sound wave of.

However, at present, rather than these sound absorbing materials,
It is desired to develop a material having a high sound absorption coefficient in a low frequency range and a thinner thickness. In addition, regarding the sound absorbing material using powder, it is the current situation that development of a sound absorbing material having a high sound absorbing coefficient in a low frequency region and a thinner thickness is desired. It is more desirable that a sound absorbing material using powder has high stability over time and does not deteriorate in performance.

[0009]

The problem to be solved by the present invention is to provide a sound absorbing material which has a high sound absorption coefficient in a low frequency range even if the thickness is thin and is excellent in handleability as a material. . Another problem to be solved by the present invention is to provide a sound absorbing material which has a higher sound absorbing coefficient in a low frequency range even when the thickness is thin and is excellent in handleability as a material.

[0010]

The first sound absorbing material of the present invention has a bulk density of 200 to 500 kg / m ³ and 1.0 × 10 ^6.
A porous material (A) having a Young's modulus of ˜1.0 × 10 ⁸ N / m ² , and 10 laminated on the surface of the porous material (A).
Bulk density of 0 kg / m ³ or less and 1.0 × 10 ^{3 to} 1.0 × 1
A porous material (B) having a Young's modulus of 0 ⁶ N / m ^2, the porous material (A) side being a sound wave incident side, and the porous material (B) side being a sound wave transmitting side. Is.

The second sound absorbing material of the present invention is 200 to 500.
Bulk density of kg / m ³ and 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ N / m
A porous material (A) having a Young's modulus of ² , a bulk density of 100 kg / m ³ or less and 1.0 × 10 ^{3 to} 1.0 × 10 ⁶ laminated on the surface of the porous material (A). Porous material (B) having a Young's modulus of N / m ² and a sound absorbing action by vibration of particles laminated on the surface of the porous material (A) on the opposite side of the porous material (B). And a powder layer that expresses the above, wherein the powder layer side is the sound wave incident side, and the porous material (B) side is the sound wave transmitting side.

It is preferable that the powder layer is a sheet-like material in which powder exhibiting sound absorbing performance is held by an acoustically transparent substrate, and the thickness of the powder layer is 5 mm or less. The powder is
0.1-1000μm average particle size and 0.1-1.5g / cm
^It is preferred to have a bulk density in the range of ³ . It is preferable that the powder is a mixed powder of a powder composed of granular particles and a powder composed of fine fiber bodies having a spring constant of 1 × 10 ² N / m or less.

The powder has granular particles and fine fiber bodies adhered to the surfaces of the granular particles, and the fine fiber bodies are 1
It is preferable to have a spring constant of × 10 ² N / m or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Sound Absorbing Material] The first sound absorbing material of the present invention is, for example,
It is a laminated material having a cross-sectional structure as shown in FIG. This sound absorbing material has a bulk density of 200 to 500 kg / m ³ and 1.0 × 10 ⁶
A porous material (A) 1 having a Young's modulus of up to 1.0 × 10 ⁸ N / m ² , and a bulk density of 100 kg / m ³ or less laminated on the surface of the porous material (A) 1 and 1 0.0 × 10 ^{3 to} 1.0
A porous material (B) 2 having a Young's modulus of × 10 ⁶ N / m ² , the porous material (A) 1 side is a sound wave incident side, and the porous material (B) 2 The side is the transmission side of the sound wave.

The porous material (A) is 200 to 500 kg / m ³
There is no particular limitation as long as it has a bulk density and a Young's modulus of 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ N / m ² . Specific examples of the porous material (A) include a rock wool sound absorbing plate composed of rock wool fiber and a binder; a board made of inorganic fiber such as rock wool or glass wool molded with a binder such as phenol resin; foaming of urethane board or the like. A sex board etc. can be mentioned.

The porous material (B) is not particularly limited as long as it has a bulk density of 100 kg / m ³ or less and a Young's modulus of 1.0 × 10 ^{3 to} 1.0 × 10 ⁶ N / m ^2. Absent. Specific examples of the porous material (B) include inorganic or organic porous materials such as rock wool, glass wool, and non-woven fabric; foamed resin bodies such as urethane. Porous material (A)
The thickness of the porous material (B) is not particularly limited, but when the thickness of the porous material (A) is 2 to 20 mm and the thickness of the porous material (B) is 5 to 50 mm, the porous material is When (B) is laminated on the porous material (A), the thickness is thin, the handleability is excellent, and the sound absorbing effect in the low frequency range can be imparted, which is preferable. Further, the thickness ratio of the porous material (A) and the porous material (B) [porous material (A): porous material (B)] is 4: 1.
If the ratio is up to 1:20, the peak frequency (f
It is preferable because r) can be set.

In the first sound absorbing material, the porous material (B) is laminated on the surface of the porous material (A). The method of laminating the porous material (B) on the porous material (A) is not particularly limited, but for example, a method of laminating using an adhesive or a method of laminating using a heat-fusible binder. , There is a method of adhering with an adhesive tape. The first sound absorbing material has a porous material (B) laminated on the surface of the porous material (A) so as to be integrated. Further, by laminating materials having different bulk densities, sound absorption due to resonance described later is achieved. Since the action occurs, the thickness can be reduced, and thus the material is excellent in handleability.

In the first sound absorbing material, the porous material (A)
The side is the sound wave incident side, and the porous material (B) side is the sound wave transmitting side. If the incident and transmitted sides of the sound wave are reversed,
It is not preferable because the sound absorbing effect in the low frequency range is reduced. A porous material with a bulk density of 500 kg / m ³ or less, such as rock wool, exhibits sound absorption characteristics in the middle and high range,
The sound absorption effect in the low frequency range is very small. Nevertheless, the first sound absorbing material has a high sound absorption coefficient in the low frequency range. The reason for this is believed to be as follows. That is, to explain with the structure shown in FIG. 1, the porous material (A) 1 on the sound wave incident side is “mass” and the porous material (B) 2 on the sound wave transmission side is “spring”. It is considered that the resonance phenomenon described above occurs, and the sound absorption function due to the resonance improves the sound absorption performance in the low frequency range. Moreover, if the incident side and the transmitting side of the sound wave are reversed in the first sound absorbing material,
The reason why the sound absorbing action in the low frequency range is lowered is that the above-mentioned sound absorbing action due to resonance cannot be obtained. Further, the porous material (A) and the porous material (B) need to have the bulk density and the Young's modulus in the above ranges. If it is outside this range, the resonance phenomenon of the porous material may not occur when a sound wave is incident, or the resonance level may decrease even if the resonance phenomenon occurs, and the sound absorption performance in the low frequency range is I can not expect it.

When the porous material (A) or the porous material (B) is used alone as a sound absorbing material, there is little or no sound absorbing effect in the low frequency range. Therefore, in order to increase the sound absorption coefficient in the low frequency range by itself, it is necessary to thicken the porous material for use. On the other hand, in the first sound absorbing material, since the sound absorbing action by resonance is obtained as described above, the porous material can be made thin.

In the sound absorbing mechanism by the resonance action, the sound absorbing coefficient becomes large in the frequency band in which the resonance of the spring-mass system occurs. When the frequency at which the sound absorption coefficient increases due to the resonance phenomenon is defined as the peak frequency (fr), fr is expressed by the following equation (1). In the formula (1), ρ ₁ is the bulk density of the porous material (A), t ₁ is the thickness of the porous material (A), and t ₂ is the thickness of the porous material (B).

Fr = [1.4 × 10 ⁵ / (ρ ₁ × t ₁ × t ₂ )] ^1/2 / 2π (1) where ρ ₁ × t ₁ is the surface weight of the porous material (A) (kg/
m ² ), the peak frequency (fr) is determined by the surface weight (kg / m ² ) of the porous material (A) and the thickness of the porous material (B). The surface weight of A),
It can be seen that the thickness of the porous material (B) on the sound wave transmitting side affects the peak frequency (fr), which is the frequency at which the sound absorption coefficient increases due to the resonance phenomenon. Porous material (A)
And the thickness, material, bulk density of the porous material (B),
It is necessary to appropriately select the physical properties such as the Young's modulus while balancing the sound absorbing performance in the low frequency range with the thinness and the handleability as a material. [Second Sound Absorbing Material] The second sound absorbing material of the present invention is, for example,
It is a laminated material having a cross-sectional structure as shown in FIG. This sound absorbing material has a bulk density of 200 to 500 kg / m ³ and 1.0 × 10 ⁶
A porous material (A) 4 having a Young's modulus of ˜1.0 × 10 ⁸ N / m ² , and a bulk density of 100 kg / m ³ or less laminated on the surface of the porous material (A) 1 and 1 0.0 × 10 ^{3 to} 1.0
Porous material (B) 3 having Young's modulus of × 10 ⁶ N / m ²
And a powder layer 5 exhibiting a sound absorbing action by vibration of particles laminated on the surface of the porous material (A) 4 on the side opposite to the porous material (B) 3 The layer 5 side is the sound wave incident side, and the porous material (B) 3 side is the sound wave transmitting side.

The second sound absorbing material is the same as the first sound absorbing material,
A porous material (A) on the side opposite to the porous material (B) has a powder layer laminated on the surface of the porous material (A), which exhibits a sound absorbing effect due to the vibration of particles, and has a lower frequency than that of the first sound absorbing material. Higher sound absorption in the range. In the first sound absorbing material, the peak frequency (fr) can be reduced by increasing the surface weight of the porous material (A) or increasing the thickness of the porous material (B). Increasing the surface weight of the material (A) may reduce the resonance level, which is not preferable. Such a point is eliminated by using the second sound absorbing material.

In the second sound absorbing material, the powder layer side is the sound wave incident side and the porous material (B) side is the sound wave transmitting side. It is not preferable to reverse the incident side and the transmitting side of the sound wave because the sound absorbing effect in the low frequency range is reduced. The reason for this is that, as in the case of the second sound absorbing material, the sound absorbing effect due to the resonance of the porous material (A) and the porous material (B) can no longer be obtained, and the incident sound wave first enters the powder layer. This is because if it does not hit, it becomes difficult to obtain a sound absorbing effect due to the vibration of the particles in the powder layer.

Porous material (A) used as the second sound absorbing material
The porous material (B) is not particularly limited as long as it has the bulk density and Young's modulus described above, and the porous material (A) and the porous material (B) described in the first sound absorbing material are used as they are. can do. In the second sound absorbing material, the porous material (B) is laminated on the surface of the porous material (A), and the powder is formed on the surface of the porous material (A) on the side opposite to the porous material (B). Body layers are stacked. As for the stacking method for the second sound absorbing material, the stacking method described for the first sound absorbing material can be used as it is.

The powder layer used in the second sound absorbing material is not particularly limited as long as it exhibits a sound absorbing effect by the vibration of the particles. Such a powder layer is a sheet-like material in which a powder exhibiting sound absorbing performance is held by an acoustically transparent base material, and the thickness of the powder layer is 5 mm or less, the handling property is improved. This is preferable because it is possible to suppress the deterioration of the sound absorption characteristics due to the unevenness of the powder, etc., and to enhance the sound absorption action in the low frequency range.

The sheet-like material is a material in which a powder exhibiting sound absorbing performance is held by an acoustically transparent base material. The structure of the sheet-like material is not particularly limited, but, for example, as shown in the cross section of FIG. 3, the powder 8 that exhibits a sound absorbing effect due to the vibration of the particles is blocked by the acoustically transparent surface sheet 6. There is a structure. The surface sheets 6 are partially adhered to each other, and the powder 8 inside the surface sheet 6 is adhered to the adhered portion 7.
The structure is divided into cell-shaped units by. In FIG. 3, the sheet-like material has a cell structure by partially adhering the surface sheet 6, and the powder 8 is divided and held inside the surface sheet 6. The adhesive portions 7 are appropriately provided, and the number of the adhesive portions 7 is increased or decreased according to the size of the area of the sheet-shaped material.

The method of partially adhering the surface sheet 6 is not particularly limited as long as the adhering portion 7 can be maintained without being damaged in a normal use condition. Examples of the method include a method of adhering an adhesive or a pressure-sensitive adhesive to adhere, a method of adhering with a binder of heat welding, and the like. The size of the cell part surrounded by the surface sheet 6 and the adhesive part 7 is several
The sound absorption characteristics are not affected in the range of cm to several tens of cm. The smaller the size of the cell portion, the better because the cell structure is not crushed due to breakage or cutting and the powder 8 is prevented from spilling out from the cell.

The acoustically transparent substrate is not particularly limited as long as it can confine the powder and prevent the powder from spilling. The surface sheet 6 is one of acoustically transparent base materials. Specific examples of the acoustically transparent base material include breathable paper, woven fabric, non-woven fabric sheet, glass cloth; polyester film having a thickness of about 50 μm or less, polyethylene sheet, polymer sheet such as vinyl sheet, and aluminum foil. Acoustically transparent topsheets such as metal foils of. The acoustically transparent base material is appropriately selected depending on the average particle size and the filling amount of the powder that exhibits sound absorbing performance.

The sheet-like material may have a structure other than the above-mentioned structure in which the powder exhibiting the sound absorbing function by the vibration of the particles is closed by the acoustically transparent surface sheet. The powder that exhibits the sound absorption effect by
Non-woven fabric of rayon, nylon, polypropylene, etc., which is filled inside a sheet-like fibrous structure such as glass wool, rock wool, etc., or a polymer in the form of a mesh that is a powder that exhibits a sound absorbing effect due to vibration of particles Examples thereof include a structure in which a cell, such as a sheet or a paper honeycomb, is filled inside and is closed by an acoustically transparent surface sheet. When the cell structure is flexible, the sheet-like material is easy to handle, which is preferable. Further, the surface sheet also needs to be integrated with the sheet-shaped fibrous structure or the cell structure, and therefore it is preferable that the surface sheet has tackiness, adhesiveness and heat-sealing property. In this case, the structure may be adhered to the binder or the like.

The powder in the sheet material is 0.1
A powder having an average particle size of ˜1000 μm and a bulk density in the range of 0.1 to 1.5 g / cm ³ is desirable. If the average particle diameter or the bulk density is out of the above range, the sound absorption characteristics in the low sound range may be deteriorated. From the viewpoint of further enhancing the sound absorption characteristics in the low sound range, the powder in the sheet-like material is
A powder having an average particle size of 300 μm and a bulk density in the range of 0.1 to 0.8 g / cm ³ is more desirable. Examples of the powder used in the present invention include flat type and peak type powders having sound absorption frequency characteristics. Unless the frequency characteristics of the sound absorption coefficient are flat type or peak type, the sound absorption characteristics in the low sound range may be inferior. Having a flat type sound absorption coefficient frequency characteristic means having a substantially constant sound absorption coefficient when a sound wave having a frequency higher than a specific frequency is incident. Here, since the specific frequency changes depending on the thickness of the powder layer, its value is not particularly limited.

It has a flat type sound absorption coefficient frequency characteristic.
The powder includes: vermiculite (average particle size: 200 to 400 μm,
Bulk density: 0.1g / cm^Three) ・ Wet silica (average particle size: 400-500 μm, bulky
Degree: About 0.1-0.2g / cm^Three) ・ Soft calcium carbonate (average particle size: 1-2 μm, bulky)
Degree: About 0.4g / cm^Three) Nylon powder (average particle size: 180-500 μm,
Bulk density: About 0.5g / cm ^Three) ・ Ferrite calcined product (average particle size: 1.3-1.5 μm,
Bulk density: about 1.0 g / cm ^Three) Gold mica (average particle size: 650 μm, bulk density: about 0.
5 to 0.6 g / cm^Three) Etc., each used alone, or
, Two or more powders are used together.

With a frequency characteristic of peak type sound absorption coefficient
Has the maximum value of the frequency characteristic curve of the sound absorption coefficient that is convex upward
That is. Here, the frequency that has a convex maximum is
The value is particularly limited because it changes depending on the thickness of the powder layer.
I don't know. Powder with peak-type sound absorption frequency characteristics
Examples thereof include silica, mica, talc and the like. Yo
More specifically, for example, gold mica (average particle size: 40 μm, bulk density: about 0.4
g / cm^Three) ・ Wet silica (average particle size: 7 to 150 μm, bulk density:
About 0.1-0.3g / cm^Three) ・ Spherical silica (average particle size: 3 to 28 μm, bulk density: approx.
0.3-0.9 g / cm^Three) Talc (average particle size: 1.5 to 9.4 μm, bulk density:
About 0.3-0.5g / cm^Three・ Acrylic resin fine powder (average particle size: 1-2 μm, bulky)
Degree: About 0.3g / cm^Three) Calcium silicate powder (average particle size: 20 to 30 μm,
Bulk density: about 0.1 g / cm ^Three・ Perlite powder (average particle size: 100-150 μm,
Density: About 0.1-0.2g / cm^Three) Fluororesin powder (average particle size: 5-25 μm, bulky)
Degree: About 0.4-0.5g / cm ^Three) ・ Bentonite (average particle size: 0.3-3.5 μm, bulk
Density: About 0.5-0.8g / cm^Three) Shirasu balloon (average particle size: 30-50 μm, bulky)
Degree: About 0.2-0.3g / cm^Three) ・ Fused silica (average particle size: 5 to 32 μm, bulk density: approx.
0.5-0.8g / cm^Three) ・ Silicon carbide powder (average particle size: 0.4 to 5.0 μm,
Density: about 0.6 to 1.1 g / cm^Three) ・ Nylon powder (average particle size: 5-250 μm, bulk
Density: About 0.3-0.5g / cm^Three) ・ Acrylic resin powder (average particle size: 45 μm, bulk density:
About 0.6-0.7g / cm^Three) ・ Carbon fiber powder (average fiber diameter: 14-18 μm, fiber
Length: 100-200 μm, Bulk density: About 0.5-0.6
g / cm^Three・ Titanium dioxide powder (average particle size: 0.1 to 0.25μ)
m, bulk density: about 0.5-0.7 g / cm^Three) Calcium carbonate powder (average particle size: 3 to 30 μm, bulk
Density: About 0.6-1.0g / cm^Three) ・ Vinyl chloride resin powder (average particle size: 130 μm, bulky)
Degree: about 0.5g / cm^ThreeBarium ferrite magnetic powder (average particle size: 1.8 to 2.2)
μm, bulk density: about 1.5g / cm^Three) ・ Silicone powder (average particle size: 0.3-0.7μ)
m, bulk density: about 0.2 to 0.3 g / cm^Three) Etc., each used alone, or
, Two or more powders are used together.

As an example, from the powder having the frequency characteristic of peak type sound absorption coefficient, the average particle diameter is 1.5 to 3.2 μm.
m, talc having a bulk density of about 0.4 g / cm ³ , and a powder having a flat type frequency characteristic of sound absorption coefficient has an average particle size of 200 to 400 μm and a bulk density of about 0.1 g / cm ³ . Choosing vermiculite, their normal incident sound absorption characteristics at a thickness of 30 mm are shown in FIG. In FIG. 4, a curve 9 shows the sound absorption coefficient characteristic of talc, and a curve 10 shows the sound absorption coefficient characteristic of vermiculite.

As the powder in the sheet-like material, a mixed powder of a powder composed of granular particles and a powder composed of fine fiber having a spring constant of 1 × 10 ² N / m or less (preferably a spring constant of 10 N / m or less). Or a powder having granular particles and fine fiber bodies attached to the surfaces of the granular particles, the fine fiber bodies having a spring constant of 1 × 10 ² N / m or less (preferably a spring constant of 10 N / m or less) It is even more desirable to use the body. By using these powders, the sound absorption characteristics in the low sound range are further improved. If the spring constant of the fine fiber body deviates from the above range, the sound absorption characteristics in the low sound range may be deteriorated. The powder composed of granular particles may be, for example, 0.1 to
A powder having an average particle size of 1000 μm and a bulk density in the range of 0.1 to 1.5 g / cm ³ , preferably 1 to 3
A powder having an average particle size of 00 μm and a bulk density in the range of 0.1 to 0.8 g / cm ³ is desirable.

Specifically, as shown in FIG. 5, a powder consisting of granular particles 11 and a powder consisting of fine fiber bodies 12 having a spring constant within the above numerical range are mixed or granular By attaching the fine fibrous body 12 of the fine fibrous body 12 to the surface of the granular grain 11 of the fine grained particle 11, the sound absorbing characteristic can be further lowered in the low-frequency range as compared with the powder of the fine grain body. Therefore, the thickness of the powder layer (or the thickness of the sheet-like material) can be further reduced.

As the fine fibrous body 12 to be adhered to and mixed with the granular particles 11, whiskers such as metal whiskers, plastic fibers, plant fibers, glass fibers and a structure in which these are aggregated are used. More specifically, mention may be made of potassium titanate whiskers, silicon carbide whiskers, zinc oxide whiskers, calcium silicate needle powder, sepiolite and the like. The fiber diameter and fiber length are not particularly limited, but usually the average fiber diameter is 0.1 to 10 μm.
And the fiber length is in the range of several μm to several tens of μm.

The microfibrous body 12 is not limited to these, and may have a spring constant of 1 × 10 ² N / m or less, preferably a spring constant of 10 N / m or less. Further, the mixing ratio of the granular particles 11 and the fine fiber bodies 12 is not particularly limited, but the weight ratio of the powder of the granular particles and the powder of the fine fiber bodies is, for example, 2
It is within the range of 0: 1 to 1:10, and preferably within the range of 5: 1 to 1: 3. If the ratio of the fine fibrous body powder is out of the above range, the sound absorption characteristics in the low sound range may be deteriorated. The method for adhering the fine fiber bodies 12 to the granular particles 11 is not particularly limited. For example, a method in which the fine fiber bodies are mixed with a diluted binder and sprayed on the granular particles flowing in hot air, or There is a method in which granular particles coated with a heat-fusible binder and fine fiber bodies are mixed and heated.

Next, the sound absorbing mechanism of powder particles will be described. When a sound wave is incident on the powder layer, the longitudinal vibration mode of the powder layer is excited, and the sound absorption coefficient increases in the frequency band in which the mode occurs. The frequency at which the sound absorption coefficient increases becomes the peak frequency (f
If r), fr can be expressed by the Young's modulus E of the powder layer, the bulk density ρ, and the powder layer thickness t as in the following expression (2).

Fr∝ (E / ρ) ^1/2 / 4t (2) The Young's modulus E of the powder layer is determined by the spring constant of the powder particle surface. Normally, the spring constant of the surface of granular particles is 1 × 10
^Since it is larger than ² N / m, the spring constant of the microfiber body is 1
If it is less than × 10 ² N / m, which is smaller than the spring constant of one granular particle, the sound absorption characteristics can be further lowered.

As described above, if the thickness of the powder layer is 5 mm or less, the handling property is improved, and the deterioration of the sound absorbing property due to the uneven distribution of the powder can be suppressed, and the sound absorbing action in the low frequency range becomes high. Therefore, the thickness is preferably 3 mm or less, and more preferably 3 mm or less. Peak frequency (fr) is powder physical property (E / ρ)
^Since it is greatly affected by ^1/2 and the thickness t of the powder layer, it is necessary to appropriately select the thickness and type of the powder layer according to the required sound absorption characteristics.

The first sound absorbing material of the present invention is a porous material (A).
And since the porous material (B) is laminated, it is excellent in handleability as a material. Furthermore, the porous material (A) acts as a mass and the porous material (B) acts as a spring,
A resonance phenomenon occurs, and the sound absorbing action due to resonance enhances the sound absorbing performance in the low frequency range, and even if the thickness is thin, the sound absorbing performance does not deteriorate in the low frequency range.

The second sound absorbing material of the present invention is excellent in handleability as a material because the porous material (A), the porous material (B) and the powder layer are laminated and integrated. There is. Further, in addition to the sound absorbing action due to the resonance described above, the sound absorbing action in the low frequency region due to the vibration of the powder layer works, so that the sound absorbing performance in the low frequency region is further enhanced, and the thickness may be thin. Also, since the powder layer has sound wave permeability,
Since the sound wave that has passed through the powder layer is incident on the inside of the porous material,
It is possible to impart sound absorption characteristics in the mid-high range.

Further, the powder layer is a sheet-like material in which powder exhibiting sound absorbing performance is held by an acoustically transparent base material, and when the thickness of the powder layer is 5 mm or less, the handling property is further improved. In addition, since the deterioration of the sound absorption characteristics due to the unevenness of the powder can be suppressed, the performance does not deteriorate over time, and the deterioration of the sound absorption performance in the low frequency range is suppressed. INDUSTRIAL APPLICABILITY The sound absorbing material of the present invention is used as a thin low-frequency range sound absorbing material as an interior material for a listening room, a musical instrument practice room, a sound absorbing duct inner sticking material, and a soundproof cover inner sticking material for a device generating noise. You can Further, by installing in a space such as a double floor or a double wall panel, an excellent floor impact noise reduction effect and a sound insulation improving effect can be obtained.

[0044]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples. (Embodiment 1) FIG. 6 is a sectional view showing the structure of an embodiment of the first sound absorbing material according to the present invention. This sound absorbing material is as described above, and is a porous material (A having a bulk density of 200 to 500 kg / m ³ and a Young's modulus of 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ N / m ² ). ) 14 and this porous material (A) 14
Bulk density of less than 100 kg / m ³ and 1.
The porous material (B) 13 having a Young's modulus of 0 × 10 ^{3 to} 1.0 × 10 ⁶ N / m ² is provided, and the porous material (A) 1
4 side is a sound wave incident side, and the porous material (B) 13 side is a sound wave transmitting side.

The porous material (A) 14 is a rock wool sound absorbing plate (thickness 12 mm, density 400 kg / m ³ , Young's modulus 7 ×).
10 ⁶ N / m ² ) and the porous material (B) 13 is rock wool fiber (thickness 12 mm, density 24 kg / m ³ , Young's modulus 3 × 10 ³ N / m ² ). The porous material (B) 13 was laminated on the porous material (A) 14 using an adhesive tape.

Porous Material (A) and Porous Material (B) Seed
The types are rock wool sound absorbing boards and rock wool fabs of the above example.
The porous material (A) is not limited to iv
0-500kg / m^ThreeBulk density and 1.0 × 10⁶~ 1.0
× 10⁸N / m^TwoAnd the Young's modulus of the porous material (B)
By the way, 100kg / m^ThreeThe following bulk density and 1.0 × 10 ^Three
~ 1.0 × 10⁶N / m^TwoWith a Young's modulus of
I just need. If it is outside this range, it will not permeate when sound waves enter.
Resonance phenomenon of quality material does not occur, or resonance phenomenon occurs.
Even if this happens, the resonance level may decrease,
Sound absorption performance in the frequency range cannot be expected.

(Embodiment 2) FIG. 7 is a sectional view showing the construction of an embodiment of the second sound absorbing material according to the present invention. This sound absorbing material is as described above, 200-500 kg / m
A porous material (A) 16 having a bulk density of ³ and a Young's modulus of 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ N / m ² and a porous material (A) 16 laminated on the surface of the porous material (A) 16. A porous material (B) 15 having a bulk density of 100 kg / m ³ or less and a Young's modulus of 1.0 × 10 ^{3 to} 1.0 × 10 ⁶ N / m ² , and a porous material (B) 1
5, a powder layer 17 that exhibits a sound absorbing effect by vibrating particles stacked on the surface of the porous material (A) 16 on the opposite side to the powder layer 17 side is a sound wave incident side, The quality material (B) 15 side is the transmission side of the sound waves.

The porous material (A) 16 is a rock wool sound absorbing plate (thickness 12 mm, density 400 kg / m ³ , Young's modulus 7 ×).
10 ⁶ N / m ² ) and the porous material (B) 15 is rockwool fiber (thickness 12 mm, density 24 kg / m ³ , Young's modulus 3 × 10 ³ N / m ² ). Further, as the powder layer 17,
As shown in FIG. 8, a sheet-like material (thickness 2 mm) in which a powder exhibiting sound absorbing performance is held by an acoustically transparent substrate is used. The sheet-like material 11 is made of silica (average particle diameter 150 μ
m, density 350 kg / m ³ ) calcium silicate acicular powder (spring constant 16 N / m, average fiber length 5 to 20 μm, average fiber diameter 0.8 μm) powder 18 (silica and silicic acid) (1: 1 by weight ratio of acicular calcium powder)
Is contained in the voids of the fibers 19 of the polypropylene-based nonwoven fabric, the surface is covered with the acoustically transparent polyester film 20 (thickness 25 μm), and the sheet is molded.

A porous material (B) was prepared using an adhesive tape.
15 was laminated on the porous material (A) 16. Further, in the same manner, the powder layer 17 was laminated on the porous material (A) 16. As described above, the sound absorbing material includes the porous material (A) and the porous material (B).
And a powder layer are laminated, and the thickness is about 26.
mm. In Example 2, the thickness of the sheet-like material, the type of powder, the physical properties, etc. are not limited to those in the above-described Examples, and are appropriately selected according to the required sound absorbing characteristics.

The powder in the sheet material is not limited to those shown above. However, if the powder is a mixed powder of powder composed of granular particles and powder composed of fine fibrous materials having a spring constant of 1 × 10 ² N / m or less, or the spring constant is on the surface of the granular particles. It is even more desirable to use a powder having a structure in which a fine fiber body having a particle size of 1 × 10 ² N / m or less is attached. That is, by using the powder having excellent sound absorbing characteristics, the sound absorbing performance in the low frequency range can be exhibited by reducing the filling amount of the powder, that is, the thickness of the powder layer. Therefore, the sound absorbing material using the sheet-like material can satisfy both the sound absorbing performance and the handleability as a material.

The base material for holding the powder, which constitutes the sheet material, is not particularly limited as long as it is acoustically transparent and can prevent the powder from spilling. Examples of such a base material (top sheet) include breathable paper, woven fabric, non-woven fabric sheet, glass cloth and the like, or polymer sheets such as polyester sheet, polyethylene sheet and vinyl sheet having a thickness of about 50 μm or less, Examples include metal foil such as aluminum foil.

In Example 2, in addition to the sound absorbing effect due to the resonance phenomenon of the spring-mass system due to the lamination of the porous material, the sound absorbing effect in the low frequency region due to the vibration of the powder layer is exerted. Sound absorption performance in the range is further enhanced. Furthermore, since the sound wave that has passed through the powder layer is incident on the inside of the porous material, it is possible to absorb the sound wave in the mid-high range. further,
In Example 2, since the powder layer is a sheet-like material in which the powder exhibiting the sound absorbing performance is held by the acoustically transparent base material, the handleability is further improved. The sheet-like material suppresses the deterioration of the sound absorption characteristics due to the uneven distribution of the powder, does not deteriorate in performance over time, and does not deteriorate the sound absorption performance in the low frequency range.

In Example 2, the thickness of the powder layer, the powder
The types, porous materials, etc. are not limited to the above examples, and are required.
It is appropriately selected according to the sound absorption characteristics. For example, porous
The types of the porous material (A) and the porous material (B) are the same as those in the above example.
Limited to wool wool sound absorbing board and rock wool fiber
No, for porous material (A), 200-500 kg / m ^Three
Bulk density and 1.0 × 10⁶~ 1.0 × 10⁸N / m^TwoNo ya
And the porous material (B) is 100 kg.
/ m^ThreeThe following bulk density and 1.0 × 10^Three~ 1.0 × 10⁶N
/ m^TwoThe Young's modulus of This range
If it is outside, the resonance phenomenon of the porous material will occur when a sound wave is incident.
Resonance that does not occur or even if resonance phenomenon occurs
There is a risk that the level will decrease, and sound absorption in the low frequency range
Performance cannot be expected.

Next, the results of measuring the sound absorbing performance of the sound absorbing materials shown in Examples 1 and 2 based on the method of measuring the sound absorption coefficient of a reverberation room in JIS A1409 will be shown. FIG. 9 shows that when the installation area of the sound absorbing material is 3 m ² , the sound absorbing material of Example 1 and rock wool are used, and the bulk density is 40 kg /
The results obtained by measuring the sound absorption coefficient of a commercially available porous sound absorbing material having a thickness of m ³ and a thickness of 25 mm (sound absorbing material of Comparative Example) are shown. In the sound absorbing material of the comparative example, the sound absorbing performance of 500 Hz or less has a reverberation room sound absorption coefficient (sound absorption coefficient) of 0.4 or less, whereas in the first embodiment, it is 50
It exhibits excellent sound absorption performance in the low frequency range of 0 Hz or less.

FIG. 10 shows the sound absorbing characteristics of the sound absorbing materials of Examples 1 and 2 when the installation area of the sound absorbing material was 1.3 m ^2, and the performances were compared. In Example 2, the powder layers having a thickness of 2 mm are laminated, and the sound absorbing performance is superior to that of the sound absorbing material of Example 1 in the low frequency range of 250 Hz or less.

[0056]

The first sound absorbing material of the present invention is excellent in handleability as a material because the porous material (B) is laminated on the porous material (A) and integrated. . Further, in the first sound absorbing material, the porous material (A) acts as a mass and the porous material (B) acts as a spring to cause a resonance phenomenon, and the sound absorbing effect due to resonance causes sound absorbing performance in a low frequency range. Even if the thickness becomes high and the thickness is thin, the sound absorption performance in the low frequency range does not decrease, and the sound absorption rate is high.

The second sound absorbing material of the present invention is excellent in handleability as a material because the porous material (A), the porous material (B) and the powder layer are laminated and integrated. There is. Further, in addition to the sound absorbing action due to the resonance described above, the sound absorbing action in the low frequency region due to the vibration of the powder layer works, so that the sound absorbing performance in the low frequency region is further enhanced, and the thickness may be thin. Also, since the powder layer has sound wave permeability,
The sound waves that have passed through the powder layer enter the inside of the porous material and also have sound absorption characteristics in the mid-high range.

Further, in the second sound absorbing material, the powder layer is a sheet-like material in which powder exhibiting sound absorbing performance is held by an acoustically transparent base material, and the thickness of the powder layer is 5 mm or less. Since it is a sheet material, the handling property is further improved, and since the powder is held by the base material, it is possible to suppress the deterioration of the sound absorption characteristics due to the uneven distribution of the powder, etc. There is no deterioration in sound absorption performance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a first sound absorbing material of the present invention.

FIG. 2 is a sectional view showing one embodiment of a second sound absorbing material of the present invention.

FIG. 3 is a cross-sectional view showing the structure of a sheet-shaped material.

FIG. 4 is a diagram showing sound absorbing characteristics of a powder layer having flat type and peak type sound absorbing characteristics.

FIG. 5 is a conceptual diagram of a powder in which fine fibrous bodies are attached to the surface of granular particles.

FIG. 6 is a cross-sectional view showing a sound absorbing material in Example 1.

FIG. 7 is a cross-sectional view showing a sound absorbing material in Example 2.

FIG. 8 is a cross-sectional view showing a sheet-shaped material in Example 2.

FIG. 9 is a diagram showing sound absorbing characteristics of the sound absorbing materials of Example 1 and Comparative Example.

FIG. 10 is a diagram showing sound absorbing characteristics of the sound absorbing materials of Example 1 and Example 2.

[Explanation of symbols]

1 Porous Material (A) 2 Porous Material (B) 3 Porous Material (B) 4 Porous Material (A) 5 Powder Layer 6 Surface Sheet 7 Adhesive Part 8 Powder 11 Granular Particles 12 Microfiber Body 13 Porous Material (B) 14 Porous material (A) 15 Porous material (B) 16 Porous material (A) 17 Powder layer 18 Powder obtained by adhering acicular calcium silicate powder to silica 19 Polypropylene non-woven fabric Fiber 20 Polyester film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G10K 11/16 G10K 11/16 D

Claims (6)

[Claims] 1. Bulk density of 200 to 500 kg / m ³ and 1.0
A porous material (A) having a Young's modulus of × 10 ^{6 to} 1.0 × 10 ⁸ N / m ² , and a bulk density of 100 kg / m ³ or less laminated on the surface of the porous material (A). 1.0 × 10 ³ -1.
A porous material (B) having a Young's modulus of 0 × 10 ⁶ N / m ² , and the porous material (A) side is a sound wave incident side,
A sound absorbing material in which the porous material (B) side is the sound wave transmitting side. 2. Bulk density of 200 to 500 kg / m ³ and 1.0
A porous material (A) having a Young's modulus of × 10 ^{6 to} 1.0 × 10 ⁸ N / m ² , and a bulk density of 100 kg / m ³ or less laminated on the surface of the porous material (A). 1.0 × 10 ³ -1.
Porous material (B) having Young's modulus of 0 × 10 ⁶ N / m ²
And a powder layer on the opposite side of the porous material (B) that exhibits a sound absorbing action by vibrating particles laminated on the surface of the porous material (A). Is the incident side of the sound absorbing material, and the porous material (B) side is the sound transmitting side of the sound wave. 3. The sheet according to claim 2, wherein the powder layer is a sheet-like material in which a powder exhibiting sound absorbing performance is held by an acoustically transparent substrate, and the thickness of the powder layer is 5 mm or less. Sound absorbing material described. 4. The sound absorbing material according to claim 3, wherein the powder has an average particle diameter of 0.1 to 1000 μm and a bulk density in the range of 0.1 to 1.5 g / cm ³ . 5. The sound absorption according to claim 3, wherein the powder is a mixed powder of a powder composed of granular particles and a powder composed of a fine fiber body having a spring constant of 1 × 10 ² N / m or less. Material. 6. The powder has granular particles and fine fiber bodies attached to the surfaces of the granular particles, wherein the fine fiber bodies are 1
The sound absorbing material according to claim 3, which has a spring constant of 10 ² N / m or less.