JP3465622B2 - Sound absorbing material - Google Patents

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 on roads, railroads, buildings and the like.

[0002]

2. Description of the Related Art A sound absorbing material which has been proposed or used has been one in which a glass fiber aggregate is used as a middle material and is wrapped with a synthetic resin film or a glass fiber woven fabric to make up for the drawbacks. Is the majority. The drawback of such a sound absorbing material is that the weather resistance is extremely poor and the durability is not good, the drying property after water absorption is poor, and the shape is deformed, or the human body is adversely affected by scattering of fiber cut pieces during processing, and sound absorption. The strength of the material itself is insufficient. Recently, in order to improve such drawbacks, an aggregate using synthetic fibers which has been surface-treated has been proposed.

In any case, sound absorbing materials used in railways, roads, constructions, etc., have sound absorbing properties, weather resistance, shape stability, strength, workability, road workability, and water retention after absorbing water. There is still a need to improve properties, flame retardancy, breathability, etc.

[0004]

SUMMARY OF THE INVENTION In view of the background of such prior art, the present invention is a sound-absorbing material satisfying good sound-absorbing properties, weather resistance, flame retardancy, processability / workability, water absorption and air permeability at the same time. Is intended to be provided.

[0005]

The present invention employs the following means in order to solve the above problems.

[0006] That is, a sound absorbing material composed of a middle material and a skin material obtained by wrapping the middle material, wherein the skin material is JIS
The air flow rate measured based on L-1096 is 80cc / cm ²
/ sec or more, the inner material has a specific gravity of 0.02 g / cc or more,
It is composed of a fiber aggregate having a surface hardness of 50 degrees or more and a thickness of 50 mm or more, in which fibers are partially adhered to each other, and the inner material and the skin material are composed of the same kind of synthetic fiber. It is a characteristic sound absorbing material.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the fibers constituting the intermediate material and the skin material must be synthetic fibers from the viewpoint of weather resistance. As the fiber material, polyester,
Any of polyamide, acrylic, polypropylene, polyethylene etc. can be used, but weather resistance, flame resistance,
From the viewpoint of recyclability, it is most preferable to use polyester fiber.

The fiber having a thickness of 1 to 100 denier can be used. As will be described later, in order to obtain a water retention amount of 0.2 g / cm ³ or less, a thick fiber has less water retention when wet, and recovery to a normal dry state is quicker. From the above viewpoints, a denier having 1 to 20 denier is preferably used since it is also good in terms of breathability. From the viewpoint of workability and handleability, the thicker the better, the more preferably 3 to 15 denier is used in view of improving the productivity with an opening machine. From the viewpoint of sound absorption, it is preferable that the fiber is thin, and in particular, in order to improve the sound absorption in the low frequency range of 200 to 1500 Hz, it is preferable to use a thin fiber of 5 denier or less.

The fiber length is preferably 10 mm or more. Either filaments or staples may be used, but in the case of staples, a fiber length of 30 to 100 mm is preferable.

The shape of the fiber cross section is a normal round cross section,
It may be a T-shaped or flat cross section, or may be a hollow fiber. Further, it may be a crimped fiber, and for example, the crimped form may be a corrugated form, a spiral type or an eclectic type of both, but a spiral type is preferably used from the viewpoint of elasticity and sag resistance. . If the Ken number is small, elasticity and hardness are insufficient, and if it is too large, processing problems occur.
0 ridges / 25 mm, more preferably 10 to 50 ridges / 25 mm are used.

In the present invention, the intermediate material has a specific gravity of 0.02 g / cc or more and a surface hardness of 50 at the same time in view of weather resistance, water absorption, form stability of construction work on site, strength and the like.
It must be more than once. Below 0.02g / cc,
For example, in terms of the normal incident sound absorption coefficient, there is a phenomenon that the sound absorption coefficient in the low frequency region of 2000 Hz or less is significantly deteriorated.
In addition, since the texture becomes soft, the shape is not stable, and the strength is not strong, so that the shape collapses when absorbing water or working on site, which makes it difficult to use. Considering the manufacturing cost and workability, the specific gravity is preferably 0.06 g / cc or less.

The intermediate material of the present invention has a surface hardness of 50 degrees or more. The term "surface hardness" as used herein means that measured by applying a rubber / plastic hardness meter F type manufactured by Kobunshi Keiki Co., Ltd. to the surface of the intermediate material. If the surface hardness is less than 50 degrees, it becomes too soft, the shape is not stable, and various troubles occur, which is not preferable. The higher the surface hardness, the better, and stable durable morphological stability can be obtained.

Fibers (main fibers) constituting such an intermediate material
The fibers need to be partially bonded to each other in order to obtain a high surface hardness. The adhesion may be performed with an adhesive or a low melting point fiber (adhesive fiber). The adhesive may be any one of synthetic resin, rubber and the like, and may be in the form of a film, a particle or a liquid. From the viewpoint of processing and practical use, a low melting point fiber (adhesive fiber) is preferably used, and a fiber made of a low melting point polymer is mixed or used, or a high melting point polyester such as polyethylene terephthalate is used as a core, and isophthalic acid is used. A core-sheath type composite fiber having a sheath of a low-melting polyester obtained by copolymerizing the above can be used. Preferably,
The latter, which is bonded by using the conjugate fiber, is preferable. The mixing ratio of the adhesive fiber and the main fiber constituting the intermediate material is preferably 5/95 to 50/50, and 10/90.
-40/60 is more preferable. If the mixing ratio of the adhesive fibers is less than 5% by weight, the adhesion is not sufficient and elasticity and hardness are lost. If the adhesive fiber is mixed at 50% by weight at most, sufficient adhesion can be given.

As the adhering means, methods such as drying, pressure and heat can be adopted, but a welding means by heat is preferably used because of the ease of processing. In this case, the adhesive fiber preferably has a melting point of 2 or higher than the melting point of the main fiber.
Fibers consisting of polymers having a low melting point of 0 to 150 ° C. are preferably used.

Further, it is preferable that the axis of the monofilament constituting the middle material is oriented substantially in the sound source direction from the viewpoint of the efficiency of sound absorption coefficient. That is, by arranging the fibers in the same direction as the direction in which sound is made, for example, a sound absorbing material with a thickness of 50 mm is
When sound is received in the thickness direction, it is preferable that the fiber axes of the constituent single fibers are arranged substantially in the thickness direction. As a result, not only the sound absorption property of vertical incidence, but also the sound absorption characteristic of obliquely incident sound is exhibited. Further, by arranging the single fiber axes in the thickness direction, particularly in the case of the back surface sound absorbing material of the bridge, the water permeation after the water absorption such as rainwater is good, and the water is not retained for a long time. Since it has good breathability and few factors that change the shape, it is possible to provide a durable product.

In the middle material of the sound absorbing material of the present invention, the fact that the single fiber axes constituting the fiber assembly are arranged substantially in the sound source direction means that, for example, card webs are laminated in almost parallel,
A fiber structure formed by partially adhering fibers to each other,
This involves cutting the fibers arranged in the running direction of the card substantially perpendicularly and directing the single fiber axis to the sound source. Furthermore, it includes arranging the single fiber axes in parallel with a plane substantially perpendicular to the compression direction by packing and compressing the fibers with high-pressure air, and orienting that plane in the sound source direction. In this case, the single fiber axis exists parallel to the surface in a plane substantially perpendicular to the compression direction, but the single fiber axis exists in the plane in a random direction.

The thicker the intermediate material is, the better the sound absorbing property is, but it is necessary that the thickness is 50 mm or more in view of economy, easiness of handling, and space as the sound absorbing material. When it is less than 50 mm, good sound absorbing performance cannot be obtained. Preferably 5
Those of 0 mm to 200 mm are used.

For example, as shown in Table 1, the thickness is 40 mm.
As for the normal incident sound absorption coefficient in the case of a specific gravity of 0.04 g / cc, the sound absorption coefficient of 90%, which is considered favorable, cannot be obtained when the sound absorption coefficient of 800 to 1600 Hz in the medium wave region is observed.

The sound absorption coefficient is measured by Denshi Sokki Co., Ltd.
It is measured based on JIS-A1405 using an automatic vertical incidence sound absorption coefficient measuring instrument type 10041A.

[0020]

[Table 1]

The intermediate material used in the present invention is obtained by mixing the main fiber and the adhesive fiber with a cotton opening and fiber opening machine, and then applying them to a card machine to make a web, and polymerizing and laminating with a cross layer to make a web laminated body. Can be produced by a method of dissolving the adhesive fiber with an air-through type heat treatment machine, a method of filling the opened and mixed fiber in a mold with high pressure air, and then heat-treating.

Next, the sound absorbing material of the present invention comprises the above-mentioned middle material wrapped with a skin material, and the air permeability of this skin material is 8
It should be 0 cc / cm ² / sec or more. The ventilation amount here is measured based on JIS L-1096. When used outdoors like a road sound absorbing material, it is necessary to quickly drain water when absorbing rainwater and to dry quickly due to its high ventilation characteristics. If it is less than 80 cc / cm ² / sec, the sound-absorbing material of the present invention has a high water retention rate, and the weight increases due to water absorption, which easily causes a change in shape. You can use as many people as you like,
It is preferably up to about 2000 cc / cm ² / sec.

The skin material must be made of the same material as the middle material. That is, for example, sound absorbing materials used on roads are required to be used in large quantities, highly public, and recyclable. Therefore, if other materials are used, it becomes necessary to disassemble and it becomes difficult to recycle. For example, a polypropylene skin material is used as the middle material of polypropylene.

When flame retardancy is required, polyester fiber is advantageous. That is, polyester 10
The one composed of 0% burns only the part in contact with the flame and can escape the burning, but the third component other than polyester, for example, natural fibers, other synthetic fibers, adhesives of other components, etc. If they are mixed, a burning effect may occur and the whole may be burned.

The form of the skin material is preferably a cloth-like one, which has strength and does not cause "smoke" when rubbed. The fibers constituting such a cloth may be staples or filaments, and for example, non-woven fabric, woven fabric or knitted fabric may be used. Among them, a nonwoven fabric composed of long fibers is most preferably used from the viewpoints of manufacturing cost and strength characteristics, and in particular, a spunbond manufacturing method is a thermal bonding method in which fibers are partially bonded to each other. This is preferable because it can eliminate "momoke" on the surface.

The thickness of the skin material is preferably thin.
It is preferably about 0.1 to 5 mm. The weight of such cloth is preferably light, but from the viewpoint of strength, it is preferably 2
0 to 200 g / m ² , more preferably 50 to 100 g /
It is better to use the thing of about m ² .

Further, it is preferable that the skin material is separated from the middle material, that is, they are not integrally bonded to each other. For example, if the middle material and the skin material are bonded with an adhesive, the middle material is elastic due to the voids and bends when used in applications that require bending of the sound absorbing material, but the skin material does not bond. Therefore, there is no elongation and it is easy for cutting to occur. Therefore, the skin material is preferably used in the form of a bag, and the one in which the intermediate material is inserted into the skin material without being bonded thereto is preferable. Here, the bag shape means that the six sides of the cubic sound absorbing material, or the sides of the boundary between the two surfaces, the front surface and the back surface, are joined by a thread or heat.

The sound absorbing material of the present invention must have a water content of 0.2 g / cm ³ or less in order to absorb rainwater, discharge it quickly, and dry it in a short time. Is preferred. If the amount of water retained exceeds 0.2 g / cm ³ , the sound absorbing material becomes heavy when absorbing rainwater, which tends to cause deformation, which makes it difficult to put it into practical use. The smaller the amount of water retained, the better, but if it is too small, capillarity will occur between the constituent fibers, making it difficult for water to escape, so it is preferably at most 0.1 g / cm ³ . The amount of water retention is 50 cm vertically, 10 cm horizontally, and 50 in height.
After measuring the weight (W0) of a cm (volume 25000 cm ³ ) middle material, the whole material was submerged in water and left for 5 minutes, then taken out, and left for 5 minutes with a vertical surface of 50 cm and a horizontal surface of 10 cm as the bottom surface. After that, the weight (W1) is measured again,
It is calculated by subtracting W0 from W1 and calculating it as the water content contained in the middle material, and converted into the amount of water per cm ^{3 of} the middle material.

Next, an example of the sound absorbing material of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the sound absorbing material of the present invention, and FIG. 2 is a sectional view thereof. In this figure, the bag-shaped skin material 1 and the middle material 2 are not integrally connected, that is, the middle material 2 is wrapped in a separated form. The fibers 3 forming the middle material 2 are arranged three-dimensionally with respect to a plane so that the fiber axes thereof face the sound source direction.

[0031]

EXAMPLES The present invention will be described in more detail by way of examples.

Example 1 First, the middle material was prepared as follows.

As the fibers to be used, polyethylene terephthalate staple raw cotton (6 denier, fiber length 64 mm,
Hollow section, Ken number 12 threads / 25 mm, Ken degree 20%,
Three-dimensional kemp product) and polyester staple core-sheath type composite fiber as adhesive fiber (polyethylene terephthalate is used for the core, and copolyester having a melting temperature of 110 ° C is arranged in the sheath, 4 denier, fiber length 51 mm ) Was prepared.

The fibers of both of these are used as the former / the latter = 70: 3
Sandwiches were laminated at a ratio of 0, mixed with a cotton opener, opened, and hung on a card machine to form a web. Further, after the web is put on the opening machine, the thickness of the web is reduced to 7 by high pressure air.
16.8 in a 5 cm, 150 cm long, 75 cm wide mold
I packed 8kg. The mold was compressed 75 cm in the length direction to form a 75 cm square.

Then, the mold was put in a high-pressure steam setter, heat-treated at 130 ° C. for 30 minutes, and then cooled. This block was sliced with a cutter having a thickness of 80 mm and a belt-shaped blade rotating in the same direction as the direction in which the mold was compressed to prepare a middle material having a size of 75 cm × 75 cm and a thickness of 8 cm.

The specific gravity of this intermediate material was 0.04 g / cc, and the surface hardness was 70 degrees. At this time, the axes of the monofilaments constituting the middle material were arranged substantially in the thickness direction.

Next, as a skin material, a non-woven fabric made of 100% polyethylene terephthalate by a spunbond thermal bond method (Basis weight: 50 g / m ² , thickness: 0.19 m)
m) prepared. The ventilation rate of this non-woven fabric is 120cc / cm ² / se
It was c.

Using this non-woven fabric, 75 cm × 75 cm,
A bag having a thickness of 8 cm was prepared, and the above-mentioned middle material was inserted into this bag to prepare a sound absorbing material.

Comparative Example 1 First, as the fibers constituting the intermediate material, polyethylene terephthalate staple raw cotton (1 denier, fiber length 64 mm,
The same polyester staple core-sheath type composite fiber as that used in Example 1 was prepared as an adhesive fiber having a circular cross section, a Ken shrinkage of 12 threads / 25 mm, a crimping degree of 12%, and a corrugated crimped product.

The fibers of both of these are former / latter = 95: 5
Sandwich laminated in the ratio of, mix with a cotton opener, open cotton,
It was hung on a card machine to make a web. After polymerizing and laminating such webs in a cross layer, the web was heat-treated by an air-sulve heat treatment machine at a hot air discharge temperature of 170 ° C. for 5 minutes, and then cooled to prepare a middle material.

The size of this intermediate material was 75 cm × 75 cm, the thickness was 8 cm, the weight was 675 g, the specific gravity was 0.015 g / cc, and the surface hardness was 20 degrees.

Next, as a skin material, a non-woven fabric made of 100% polyethylene terephthalate by a spunbond thermal bond method (Basis weight: 260 g / m ² , thickness: 0.62).
mm) prepared. The ventilation rate of this non-woven fabric is 11cc / cm ² / s
It was ec.

Using this non-woven fabric, 75 cm × 75 cm,
A bag having a thickness of 8 cm was prepared, and the above-mentioned middle material was inserted into this bag to prepare the sound absorbing material of Comparative Example 1.

Table 2 shows the results of measuring the performances of the two intermediate materials. As is clear from Table 2, it can be seen that the material of Example 1 exhibits excellent sound absorption properties as compared with the material of Comparative Example 1.

[0045]

[Table 2]

[0046]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a sound absorbing material which is stable and has good sound absorbing properties, handling workability, water absorbing and draining properties, air permeability, and durability.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a sound absorbing material of the present invention.

FIG. 2 is a cross-sectional view showing an example of the sound absorbing material of the present invention.

[Explanation of symbols]

1: Skin material 2: Middle material 3: Fiber

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G10K 11/162 B32B 5/26 E01F 8/00 E04B 1/86 G10K 11/16

Claims (6)

(57) [Claims] 1. A sound absorbing material comprising a middle material and a skin material obtained by wrapping the middle material, wherein the skin material is JIS L-10.
The air permeability measured based on 96 is 80 cc / cm ² / sec or more, and the inner material has a specific gravity of 0.02 g / cc or more and a surface hardness of 5
A fiber aggregate having a thickness of 0 ° or more and a thickness of 50 mm or more, in which the fibers are partially adhered to each other, and the middle material and the skin material are composed of the same kind of synthetic fiber. Sound absorbing material. 2. The sound absorbing material according to claim 1, wherein the water content of the inner material is 0.2 g / cm ³ or less. 3. The sound absorbing material according to claim 1, wherein the single fiber axes constituting the fiber assembly are arranged substantially in the sound source direction. 4. The sound absorbing material according to claim 1, wherein the skin material is a long fiber non-woven fabric in which fibers are partially bonded to each other. 5. The sound absorbing material according to claim 1, wherein the skin material has a bag shape. 6. The sound absorbing material according to claim 1, wherein the skin material and the middle material are separated from each other.