JPH05158483A - Sound absorbent material - Google Patents

Abstract

PURPOSE:To obtain the sound absorbent material consisting of powder which is further lowered in sound absorption characteristic to a lower frequency region than the conventional powders at the same thickness by sticking structural bodies of fibers, such as metallic whiskers onto the particle surfaces of the powder of mica, silica, etc., having a good sound absorption characteristic in a low-frequency region. CONSTITUTION:The structural bodies 3 of the silicon carbide whiskers (8.5X104N/m<2> dynamic Young's modulus) having the grain size of 1/10 the grain size of the particles 1 of the silica powder having, characteristic 150mum average grain size are stuck to the surfaces of the particles 1, by which the sound absorption characteristic of the silica powder is lowered to the lower frequency region. This powder is not limited to the silica and any powders are usable, insofar as the powders absorb sound by the vibration of the powder layer. The structural bodies 3 of the fibers are not limited to the silicon carbide whiskers and the structural bodies of any fibers are usable, insofar as the fibers have <=1X10<3>N/m<2> dynamic Young's modulus. The grain size thereof is not limited to 1/10 the grain size of the particles of the powder. Further, the surfaces of the powder particles 1 may be coated fully with the structural bodies 3 of the fibers. The structural bodies 3 of the fibers are not limited to the assemblies formed by blending straight fibers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material used for acoustic processing in listening rooms, musical instrument practice rooms and the like.

[0002]

2. Description of the Related Art One of the big problems in a small space such as a listening room or a musical instrument practice room is a booming phenomenon in which a sound of a specific frequency is emphasized and sounds like "pompon".

This is a phenomenon caused by the resonance of the sound due to the relationship between the wavelength of the sound generated from the stereo device and the musical instrument and the size of the room.

That is, in a listening room, a musical instrument practice room, etc., in the sound wavelength range of 20 to 20 kHz (that is, in the range of 1.7 cm to 17 m), the sound in the low frequency range (500 Hz or less) This is caused by the fact that the wavelength is almost the same as the length of one side of the room, and normally, when the indoor space is large like a concert hall, its frequency falls below the audible range, so it is not a problem, In a small space such as a listening room or a musical instrument practice room, it appears in the low frequency range and becomes a problem because it is evaluated as "the sound is muffled" or "the sound is not clean".

In order to eliminate this booming phenomenon, it is sufficient to absorb the sound in the low range. Conventionally, as a sound absorbing material in the low sound range, powder as disclosed in Japanese Patent Application No. 02-223529 is known.

[0006]

In the above-mentioned prior art, the sound absorption characteristics of the powder are generally mountain-shaped with the sound absorption peak frequency fr as the center shown by the alternate long and short dash line in FIG. The sound absorbing mechanism is to absorb sound energy by longitudinal vibration of the powder layer. FIG. 4 schematically shows a state of longitudinal vibration over one period (second) of the powder layers laminated in seven layers. This fr can be expressed by the following equation by Young's modulus E of the powder layer, bulk density ρ, and powder layer thickness t. In glass wool, which is commonly used as a sound absorbing material,
As shown by the dotted line in FIG. 5, it has a high sound absorption coefficient in the low sound range, but it is still insufficient from the viewpoint of the audible range.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sound absorbing material made of a powder having the same thickness and a sound absorption characteristic lower than that of a conventional powder. Is.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to powder particles 1
The sound absorbing material is characterized by having a fiber structure 2 attached to the surface thereof, and is mainly filled in a box body 4 having an opening on one side as shown in FIG. 3, and the opening is acoustically transparent. It is used as a panel closed with the sheet 5.

The panel has a width of 300 to 900.
[Mm] and a height of 1800 to 2400 [mm].

As the powder, the powder used in the present invention usually has a particle size of about 0.1 to 1000 μm and a bulk density of about 1.0 g / cm ³ , and gold mica powder,
Examples thereof include silica powder, acrylic ultrafine powder, talc powder, calcium silicate powder and the like. For example, average particle size 40μ
m, gold mica powder having a bulk density of 0.37 g / cm ³ , average particle size of 1.7 to 7.5 μm, bulk density of 0.06 to 0.14 g
/ Cm ³ wet silica powder, average particle size 23 to 28 μm, bulk density 0.84 to 0.92 g / cm ³ spherical silica powder,
The average particle diameter of 1 to 2 [mu] m, acrylic ultrafine powder of bulk density 0.30 g / cm ^3, average particle size 1.5～3.2Myuemu, talc powder bulk density 0.25 g / cm ^3, average particle diameter 20~30μ
Calcium silicate powder having m 2 and a bulk density of 0.08 g / cm ³ may be mentioned. The thickness of the packed layer of powder is usually 1
The range is about 100 mm.

As the fiber structure, there are used metal whiskers, plastic fibers, plant fibers, glass fibers and the like which are finely cut and mixed or wound. In addition, box 4
Wood, gypsum board, calcareous board, wood wool cement board,
A piece of wood cement board, a breathable woven fabric for the acoustically transparent sheet 5, such as Saran cloth, glass cloth,
Alternatively, a thin film having a thickness of about 0.05 mm or less, such as a polyethylene sheet or a vinyl film, is generally used.

[0012]

[Operation] In the sound absorbing material of the present invention, the soft fiber structure is sandwiched at the contact point of the particles of the powder with respect to the conventional single powder having good sound absorbing characteristics in the low sound range, so that the Young's modulus becomes small and the sound absorbing characteristics are improved. The bass range can be further improved.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view relating to a first embodiment of the present invention, in which the surface of a particle 1 of silica powder having an average particle size of 150 [μm] has a particle size of 1/10 of the particle 1 of silicon carbide. The structure 2 having whiskers (dynamic Young's modulus: 8.5 × 10 ⁴ [N / m ² ]) is adhered. Thus, by adhering the structure 2 of silicon carbide whiskers, silica powder 5, the sound absorption characteristics are made lower than the one-dot chain line in FIG. 5. The powder of the present invention is not limited to silica, and as described above, it absorbs sound by longitudinal vibration of the powder layer. Any powder will do.

Further, the fiber 1 structure 2 is not limited to the silicon carbide whiskers, and its dynamic Young's modulus is 1 × 10.
Any fiber structure having a fiber density of ⁵ [N / m ² ] or less may be used, and the particle size is not limited to 1/10 of the particle size of the powder. Further, the entire surface of the powder particles may be covered with the fiber structure 2.

The fiber structure 2 as shown in FIG. 1 is not limited to an assembly in which linear fibers are mixed, but a coiled ceramic fiber or the like may be used as shown in FIG.

[0017]

EFFECTS OF THE INVENTION The present invention is a powder sound absorbing material characterized in that a fiber structure is attached to the surface of a powder particle having good sound absorbing characteristics in the low sound range. The sound absorption characteristics can be made lower than that of the powder alone.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a plan view showing another embodiment of the present invention.

FIG. 3 is a partially cutaway sectional view showing a usage state of the sound absorbing material according to the present invention.

FIG. 4 is a diagram showing a sound absorption principle of powder.

FIG. 5 is a graph showing sound absorption characteristics.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Powder particles 2 Fiber structure (silicon carbide whisker structure in the example) 3 Box body 4 Acoustically transparent sheet 5 Powder layer

Claims (1)

[Claims] 1. A sound absorbing material, characterized in that a fiber structure is attached to the surface of powder particles.