JP2001236076A - Sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of efficiently producing a sound absorbing material satisfying good sound absorption characteristic, weatherability, form stability, high tenacity, workability, mounting workability, water-retaining characteristics, fire retardance, ventilatability, etc. SOLUTION: This sound absorbing material is composed of a center material and surface skin cloth of synthetic resin fibers cladding this center material and this center material is formed by laminating at least two layers fiber assemblies partially adhered with the synthesize fibers to each other.

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, railways, buildings, and the like.

[0002]

2. Description of the Related Art A conventional sound absorbing material mainly uses a glass fiber aggregate as a middle material. Such sound-absorbing material has an extremely low elongation of glass fiber, so the production, transportation, construction,
Furthermore, even after installation, breakage and shape collapse are likely to occur. Then, there is a concern that not only the sound absorbing performance is reduced, but also the danger due to scattering of glass fiber pieces. In order to make up for the drawbacks, those in which a glass fiber assembly is wrapped with a synthetic resin film or a glass fiber fabric have been developed, but are still insufficient.

Further, in order to solve the problem of breakage, there has been proposed a fiber assembly using synthetic fibers. In this case, a surface material such as a cloth or a film is attached to a surface of the structure, which is exposed to the outside, for protection, handling, and appearance of the fiber assembly. However, these are low in versatility due to the problem of combustion which may be caused by an adhesive or a surface finishing agent in the skin material, and are not widely used at present.

[0004]

SUMMARY OF THE INVENTION In view of the background of the prior art, the present invention satisfies good sound absorption, form stability, strength, workability, mounting workability, flame retardancy, etc. It is an object of the present invention to provide a technology for efficiently producing a sound absorbing material satisfying the characteristics.

[0005]

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

That is, a sound absorbing material comprising a middle material and a skin material surrounding the middle material, wherein the middle material is formed by laminating at least two fiber aggregates in which fibers are partially adhered to each other. It is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the fibers constituting the middle material and the skin fabric must be synthetic fibers in view of strength and handleability. Such fiber materials include polyester, polyamide, acrylic, polypropylene,
Polyethylene or the like can be used, but polyester fiber is most preferably used in terms of weather resistance, flame retardancy, and recyclability.

Further, it is preferable that the middle material and the skin fabric are composed of the same kind of synthetic fiber. It is desirable that sound-absorbing materials and the like used on roads be used in large quantities and have high publicity, and be recyclable. In this case, recycling is facilitated by using the same type of synthetic fibers. Here, the same type does not need to be composed of exactly the same components, and may be any combination such as polyesters, polyamides, acrylics, polypropylenes, polyethylenes, etc. The components may have different intrinsic viscosities or the like, or the third component may be copolymerized.

The sound-absorbing material of the present invention is obtained by covering a middle material with a skin fabric. The term “wrapping” refers to a structure in which a skin fabric is formed in a bag shape and an intermediate material is stored therein. By doing so, the skin material can be arranged on the surface without bonding the skin material and the middle material with an adhesive or the like or joining them with a thread or the like. Then, the flexibility of the sound absorbing material is not hindered, and the handleability at the time of construction on site is improved. Further, since it is not necessary to apply an adhesive between the intermediate material and the skin material, flame retardancy is improved.

Here, the bag shape may be any shape as long as it has a shape surrounding the middle material, and is not particularly limited. For example, when the middle material is a rectangular parallelepiped, The skin material corresponding to each surface may be joined into a bag shape by fusing, or two skin materials may be joined by joining to form a so-called envelope.

This skin material may be formed into a bag-like material, and then the middle material may be inserted. Alternatively, the middle material may be wrapped with a cloth and then processed into a bag shape.

The intermediate material covered by the skin fabric is formed by laminating at least two fiber aggregates. These fiber aggregates need not necessarily be joined. The performance of the fiber assembly largely depends not only on the thickness but also on the material of the constituent fibers, fineness, cross-sectional shape, density, etc., but by combining the fiber assemblies in different states, the desired sound absorbing performance can be efficiently obtained. be able to. Moreover, even if the sound absorbing material is burned by a fire, the spread of the fire can be prevented more safely by dropping the independent fiber aggregate. Further, in order to obtain sufficient sound absorbing performance, a certain thickness or more is required. However, the thickness of a conventionally produced fiber aggregate called so-called hard cotton (solid cotton) is generally When producing fiber aggregates of about 3 cm and more than 5 cm on the equipment, the production efficiency during heat treatment often decreases and the cost greatly increases, and a plurality of general-purpose fiber aggregates with a thickness of about 3 cm are laminated. It is effective to use it as a middle material.

[0013] The fiber assembly constituting the middle material is formed by partially bonding fibers to each other. The bonding may be performed by using an adhesive or a low-melting fiber (adhesive fiber). The adhesive may be any material such as a synthetic resin and rubber, and may be in any shape such as a film, a particle, and a liquid. From a processing and practical point of view, a low-melting fiber (adhesive fiber) is preferably used. A fiber made of a low-melting polymer is used as a mixture, or a high-melting polyester such as polyethylene terephthalate is used as a core and isophthalic acid Core-in-sheath type composite fibers having a low melting point polyester obtained by copolymerizing the same as a sheath can be used. Preferably, the latter composite fiber is used for bonding. The mixing ratio of the adhesive fiber and the main fiber constituting the intermediate material is 5/95.
50/50 is preferable, and 10/90 to 40/60 is more preferable. By setting the mixing ratio of the adhesive fibers to 5% by weight or more, it is possible to adhere to the extent of forming a fiber aggregate, and to obtain elasticity and hardness. In addition, if the adhesive fibers are mixed at most 50% by weight, sufficient adhesion can be provided.

As the bonding means, a method such as drying, pressure and heat can be adopted. However, a heat welding means is preferably used from the viewpoint of simplicity of processing. In this case, as the adhesive fiber, the melting point of the main fiber is preferably 2 mm.
It is preferable to use a fiber made of a polymer having a melting point lower by 0 to 150 ° C.

The middle material used in the present invention is obtained by mixing the main fiber and the adhesive fiber with a cotton opener or a fiber opening machine, then setting the web on a carding machine, polymerizing and laminating with a cross layer to form a web laminate. Can be produced by means of dissolving the adhesive fibers with an air-through type cotton wool producing machine, or a method of heat-treating the fibers which have been spread and mixed into a form by high-pressure air.

The fineness of the fiber used in the fiber aggregate of the present invention is not particularly limited, and for example, a fineness of 1 to 100 dtex can be used. When using fibers of relatively large fineness, the water retention when wet is small, the recovery to a dry state which is a normal state may be quick, and it also has favorable performance in air permeability. Become. Also, the thicker the better from the viewpoint of workability and handling,
In particular, it is possible to improve the productivity when the raw cotton is opened by the opening machine. On the other hand, thinner fibers are better in terms of sound absorbing properties, and it is preferable to use thin fibers of 5.5 dtex or less in order to improve sound absorbing properties particularly in the low sound range of 200 to 1600 Hz. Therefore, these findings can be used as a reference when designing a fiber assembly as a sound absorbing material, and are preferably 2 to 20 dtex, more preferably 3.3 to 15 dtex. It is also effective to mix raw cotton of various finenesses.

The length of the fiber is preferably at least 10 mm. Filament or staple may be used, but in the case of staple, the fiber length is preferably 30 to 100 mm.

The shape of the fiber cross section is a normal round cross section,
Either T-shaped or flat shaped cross sections may be used, and hollow fibers may be used. In addition, a fiber having crimping may be used. For example, the crimped form may be any of a corrugated shape, a spiral type or a compromise type of both, and a spiral type is preferably used from the viewpoint of elasticity and sag resistance. . When the number of shrinkage is small, the elasticity and hardness are insufficient, and when the number is too large, trouble occurs in processing.
0 peaks / 25 mm, more preferably 8 to 50 peaks / 25 mm are used.

In the present invention, the fiber aggregate used for the intermediate material preferably has an apparent density of 0.02 g / cm ³ or more. Here, the apparent density refers to the mass per volume with respect to the intermediate material cut out without load, including the space between the fibers of the fiber assembly or, in the case of a hollow fiber, the space within the fiber. 0.0
By setting it to 2 g / cm ³ or more, for example, in terms of the normal incidence sound absorption coefficient, the sound absorption coefficient in a low frequency region of 2000 Hz or less can be favorably maintained. Further, since the form is stable and has strength, the form is less likely to collapse during water absorption or on-site work. More preferably, at 0.025 g / cm ³ or more, good sound absorbing performance can be obtained. On the other hand, in consideration of manufacturing cost and workability, the apparent density is 0.06 g / cm.
³ or less is preferred.

As for the thickness of such a middle material, the greater the thickness, the better the sound absorbing property, and it can be set to a desired thickness by laminating. However, from the viewpoint of economy, ease of handling, and space as a sound absorbing material, it is preferable. Is 30 to 500 mm, more preferably 70 to 200 mm.

For example, as shown in Table 1, the thickness is 30 mm
When the specific gravity is 0.04 g / cm ³ , the normal incidence sound absorption coefficient is considered to be good in view of the sound absorption coefficient of 800 to 1600 Hz, which is a medium wave region, in order to obtain a good sound absorption coefficient of 90%. It turns out that the thing of 50 mm or more is preferable.

[0022]

[Table 1]

The skin cloth enclosing the middle material has high strength,
Those which do not cause "mocking" upon rubbing are preferred.
The fibers constituting such a fabric may be either staples or filaments, and for example, non-woven fabrics, woven fabrics and knits can also be used. Among these, from the viewpoint of production cost and strength characteristics, a nonwoven fabric composed of long fibers is most preferably used, and particularly by a spun bond method,
The method using a thermal bond fabric in which the fibers are partially adhered to each other is preferable because "sprinkling" on the fabric surface can be eliminated.

In the present invention, the skin material covering the middle material is:
It is important that the fabric is a fabric. When the skin material is a film, the sound absorbing performance is impaired. Moreover, it becomes easy to burn. The air permeability of the skin fabric is preferably 80 cc / cm ² / sec or more. 80 cc / cm ² / sec
By doing so, it is possible to maintain sound absorption performance particularly in a high frequency region of 3000 Hz or more. Considering water repellency and the like, it is preferably 2000 cc / cm ² / sec or less.

Further, the basis weight of the skin fabric of the present invention is preferably low from the viewpoint of cost, as long as the above-mentioned air permeability is obtained, but from the viewpoint of strength, it is preferably 20 to 200 g / g.
m ² , more preferably 40 to 150 g / m ² .

The skin cloth used in the present invention has a thickness of 1 mm.
The following is preferred. By setting the thickness to 1 mm or less, it is easy to form a bag, and it is easy to store the middle material,
Productivity and handling are improved.

The method of joining the skin material of the present invention into a bag shape is a method of joining with a thread or a stapler,
A method of bonding with an adhesive or an adhesive tape, or a method of directly fusing with a so-called ultrasonic sewing machine can also be used. In particular, direct fusion with an ultrasonic sewing machine can be efficiently processed into a bag shape.

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. In this figure, the bag-shaped skin material 1 and the middle material 2 are not integrally joined, that is, they are separated from each other.
Is wrapped. Further, the heat-sealed portion 3 joins the skin material 1 by heat-sealing. The fibers 3 constituting the middle material 2 are arranged three-dimensionally with respect to a plane such that the fiber axis is directed to the sound source direction.

The sound-absorbing material of the present invention preferably exhibits a self-burning property in combustion performance, which is achieved by using a polyester material as described above. Here, the combustion performance is defined by a combustion test method described later.

[0030]

The present invention will be described in more detail by way of examples. The evaluation method used in the present invention will be described. The evaluation method not described here basically conforms to the method defined in JIS. (1) Aeration rate According to JIS L-1096. (2) Sound absorption coefficient According to JIS A-1405. However, the measuring device is an automatic normal incidence sound absorption coefficient measuring instrument type 100 manufactured by Denshi Sokki
41A was used. The unit of the sound absorption coefficient is%. (3) Combustion performance According to JIS D-1201. However, humidity control is 22 ℃
Performed at × 50% RH. In addition, the test piece is 350 mm long, 100 mm wide, and 12 m thick, with the inner material wrapped with four skin materials.
m. (4) Apparent density According to JIS K-6401.

Example 1 Raw fibers of polyethylene terephthalate (6.6 decitex, fiber length 64 mm, hollow cross section, number of shrinkage 12/25 mm, degree of shrinkage 20%, shrinkage of three-dimensional solid) are used as fibers.
And, as the adhesive fiber, polyester core-sheath type composite raw cotton (polyethylene terephthalate is used for the core, and a copolymer polyester having a dissolution temperature of 110 ° C. is provided for the sheath,
4.4 dtex, fiber length 51 mm).

The ratio of the former and latter fibers was 70/3.
Sandwich is laminated at a ratio of 0, mixed and opened with a cotton opener, put on a card machine to form a web, and the web is laminated in multiple layers with a cross layer. After performing a heat treatment at a hot-air discharge temperature of 150 ° C. for 2 minutes using a mold cotton wool manufacturing machine, the fiber assembly A of the present invention was formed by cooling.

The fiber assembly A is 3.3 cm thick, has a specific gravity of 0.032 g / cm ³ , and has a length of 100 cm and a width of 10 cm.
It was cut to 0 cm to obtain a middle material of the present invention.

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

Using such a non-woven fabric, a gusset portion is heat-sealed with an ultrasonic sewing machine to form a bag-like shape. Three pieces of middle material are laminated and inserted into the bag. The sound-absorbing material of the present invention was produced by fusing and closing via a heat-adhesive tape.

The sound absorption coefficient of this sound absorbing material at normal incidence was measured, and as shown in Table 2, excellent sound absorbing performance was shown. Also, J
When the combustion performance was evaluated based on IS D-1201, the combustion did not reach the A-marked line, and was classified as “self-extinguishing”.

Comparative Example 1 Using the two kinds of raw cotton used in Example 1, an attempt was made to produce a hard cotton having a thickness of 10 cm in the same process as in Example 1. However, the number of laminated webs was too large to be produced by a normal hard cotton producing machine. Therefore, using a hard cotton processing machine capable of thick heat treatment, the interval between the laminated webs during the heat treatment was set to 9.5 cm to produce a hard cotton, but the hot air discharge temperature was 150 ° C. for 2 minutes. Under the conditions, sufficient adhesion could not be obtained, and the form was not stable as a middle material of the sound absorbing material.

Comparative Example 2 A fiber aggregate A prepared in the same manner as in Example 1 was used as an intermediate material.

Next, a film (thickness: 25 μm) made of polyethylene terephthalate was prepared as a skin material.
This film had an air permeability of 0 cc / cm ² / sec and had no air permeability.

Using such a film, a gusset portion is heat-fused with a double-sided adhesive tape to form a bag shape, and three intermediate materials are laminated and inserted into the bag, and finally, the mouth portion of the bag is formed. Was similarly closed to produce a sound absorbing material of the present invention.

When the normal incidence sound absorption coefficient of this sound absorbing material was measured, as shown in Table 2, the sound absorption coefficient was significantly reduced in a high frequency region of 2000 Hz or more. Also, JIS D-12
When the combustion performance was evaluated on the basis of No. 01, the burning speed of the skin material exceeded 100 mm / min and was classified as "flammability".

Example 2 Fiber aggregate A used in Example 1 as a middle material and fineness 6.
The fiber assembly B prepared under the same conditions as in Example 1 was replaced with B / A /, except that 2.2 dtex of raw polyethylene terephthalate was used instead of 6 dtex of raw cotton.
A sound absorbing material was prepared under the same conditions as in Example 1 except that three layers were used in the order of B.

The normal incidence sound absorption coefficient of this sound absorbing material was measured. As shown in Table 2, the sound absorbing material exhibited excellent sound absorbing performance even in the low frequency region as compared with Example 1.

[0044]

[Table 2]

[0045]

According to the present invention, a sound-absorbing material which satisfies good sound absorbing properties, weather resistance, form stability, strongness, workability, workability for mounting, water holding properties, flame retardancy, air permeability and the like can be efficiently produced. We can provide technology to produce well.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of the sound absorbing material of the present invention for clarifying a part of the internal structure, and shows that a skin material is a forging material using two fiber aggregates as an intermediate material. Is shown.

[Explanation of symbols]

 1: skin material 2, 3: fiber aggregate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D001 CB01 CC02 CD03 2E001 DF04 FA30 GA11 GA23 GA26 GA29 GA42 HD11 LA04 LA05 4F100 AK42A AK42B AT00A BA02 BA10B BA11 BA13 DD32 DG01A DG01B DG04B DG06A DG11A JA1 JL09 YY00A YY00B 5D061 AA06 AA22 BB21 DD02

Claims (8)

[Claims] 1. An intermediate material comprising at least two fiber aggregates, each of which is composed of a middle material and a skin fabric of a synthetic fiber surrounding the middle material, wherein the synthetic fibers are partially adhered to each other. Sound absorbing material. 2. The sound-absorbing material according to claim 1, wherein the air permeability of the skin fabric measured according to JIS L-1096 is 80 cc / cm ² / sec or more, and the thickness of the skin fabric is 1 mm or less. 3. The sound absorbing material according to claim 1, wherein the apparent density of the middle material is 0.02 g / cm ³ or more. 4. The sound-absorbing material according to claim 1, wherein the middle material and the skin fabric are composed of the same kind of synthetic fiber. 5. At least one of the fiber aggregates constituting the middle material
The sound absorbing material according to any one of claims 1 to 4, wherein the sheet is different from other fiber aggregates. 6. The sound-absorbing material according to claim 1, wherein the skin material is a long-fiber nonwoven fabric in which fibers are partially adhered to each other. 7. The sound-absorbing material according to claim 1, which exhibits self-extinguishing properties in combustion performance measured according to JIS D-1201. 8. The sound-absorbing material according to claim 1, wherein the thickness of the middle material in the laminating direction is 5 cm or more.