WO2009125742A1 - Sound-absorbing composite structure - Google Patents

Abstract

A sound-absorbing composite structure obtained by combining and uniting a skin layer constituted of one layer or two or more superposed layers of a nonwoven fabric comprising a polymeric material, e.g., a polyester, polyethylene, or nylon, and having a diameter of 11-35 µm in terms of equivalent single-fiber diameter (flow resistance, 3.5×10⁵ to 7×10⁶ N⋅sec/m⁴) with a base layer consisting mainly of a porous material constituted of polymer fibers (flow resistance, 0.5×10⁴ to 3.5×10⁴ N⋅sec/m⁴). This composite has a unit-area flow resistance of 1×10⁴ to 7×10⁴ N⋅sec/m⁴.

Description

Composite sound absorbing structure

The present invention relates to a novel invention relating to a sound absorbing structure using a fibrous porous material.

Conventionally, various porous materials have been proposed as sound absorbing materials, and among them, fiber-based sound absorbing materials are the most commonly used as a base material. Glass wool has long been preferred as a fiber-based sound absorbing material, but recently, polyester fiber-based sound absorbing materials have been used because of environmental problems, recycling, sound absorbing performance, work environment preservation, long-term durability, and the like. In most cases, this polyester fiber-based sound absorbing material is treated with a non-woven fabric composed of polyester fibers to adjust the water repellency, durability, and sound absorbing properties, and the heat-melt material is heat-sealed to the base material layer. It is used by arranging the side surface on the sound incident side.

Although the overall unit area flow resistance (hereinafter sometimes referred to simply as "flow resistance") due to the base material layer and the skin layer is adjusted to provide sound absorption characteristics, practical use such as strength, durability, processability, etc. In terms of sound absorption performance, there are problems in terms of sound absorption performance as well, but in terms of sound absorption performance, there is a limit in trying to obtain higher sound absorption performance within a certain limited thickness. was there.

In general, porous materials such as glass wool and polyester fibers exhibit sound absorption properties because sound waves incident from the surface of the porous material vibrate air in a three-dimensionally formed interstice between fibers. As a result, viscous resistance is generated, and incident acoustic energy is consumed as heat energy, and as a result, it is the main sound absorption mechanism that reflected acoustic energy is suppressed.

It is closely related to the flow resistance, and the point of development is how to adjust the appropriate flow resistance to obtain higher sound absorption performance. If the flow resistance is too small, the air will move easily, if the flow resistance is too large, the air will not move, the conversion efficiency from incident acoustic energy to thermal energy will be reduced, and high sound absorption performance can not be obtained. It can be said that the possibility of development of a new structure still remains. In addition, although not a main factor, it is thought that the friction between constituent fibers, the internal attenuation of the fibers themselves, etc. also contribute to the conversion to thermal energy.

The unit area flow resistance is defined by the following equation from the velocity when a constant minute air flow V flows in the direction perpendicular to the surface of the material and the pressure difference between the two surfaces of the material.
R = ΔP / (V · d)
R: Unit area flow resistance [N · sec / m ⁴ ]
ΔP: Pressure difference between both sides of the material V: Air flow rate per unit area [m ³ / (m ² / sec)]
d: Thickness of sample (m)

To measure the unit area flow resistance, insert a sound absorbing material of φ30 mm and thickness 30 mm into a metal tube of φ29 mm and use Kato Tech KES-F8-API Permeability Tester (flow velocity 4 × 10 ⁻² m / Sec).

In the case of a composite sound absorbing structure in which the surface layer and the base material layer are combined, the flow resistance of the composite determines the sound absorption coefficient of the sound absorbing material. This flow resistance is a: of the porous material which is a base material layer Changing the density, b: changing the diameter or blending ratio of fibers constituting the porous material, c: changing the fiber characteristics constituting the porous material, d: non-woven fabric of the skin layer (for example, spunbond) It can be controlled by changing characteristics and specifications, but at present it can not be said that it is optimized in the prior art.

According to the knowledge of the prior art, for example, in order to improve the sound absorbing performance, the diameter of the single fiber constituting the nonwoven fabric of the skin layer is recommended to be 10 μm or less, preferably 5 μm or less (Japanese Patent No. 3494332). However, in this case, although it is easy to obtain the sound absorbing performance, there are many extremely inconvenient aspects such as strength, durability, composite manufacture with the base material layer, and difficulty in handling on a processed surface (such as wrinkles) in practical use.

In addition, as a method of enhancing the sound absorption performance of the polymeric porous material, a film structure may be inserted or formed between the surface layer and the base material layer, and the sound absorption performance in the middle and low frequency bands is considerable. Although it improves, on the other hand, the sound absorption performance in the high frequency band generally decreases, and it is not suitable for the purpose of improving the sound absorption performance in a wide frequency band from the middle and low frequency bands to the high frequency band.

The present invention has been made in view of the prior art as described above, and its object is to use a non-woven fabric using a specific single fiber diameter, and a skin layer and polyester made of one or more non-woven fabric. A porous sound absorbing material in which the sound absorbing performance is further improved in a wide frequency band from low to high bands without complexing the fiber or the matrix layer mainly composed thereof and thickening the volume as a sound absorbing structure It is to provide at an appropriate cost.

The first aspect of the present invention is a composite integration of a skin layer on which at least one non-woven fabric of a polymeric material such as polyester, polyethylene, nylon, etc. is laminated, and a matrix layer mainly composed of a porous polymer fiber material. The composite sound absorbing structure is characterized in that the unit area flow resistance of the composite of the skin layer and the base material layer is preferably 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ .

The polymer fiber-based porous material of the matrix layer is mainly made of polyester fibers, and the orientation of this material is either longitudinal orientation, transverse orientation, or irregular orientation. In addition, the polymer fiber-based porous material is a melt fiber having a melting point at 100 to 200 ° C. and one having a fiber diameter of 2 to 20 denier appropriately mixed to have an area density of 500 to 2500 g / m ² integrally. A heat-molded product is exemplified, and the unit area flow resistance of the base material layer is 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ .

The nonwoven fabric used for the skin layer has a cross-sectional shape of single fiber of circular or flat shape, equivalent single fiber diameter is 11 to 35 μm, and area density is 50 to 130 g / m ² Or a single layer of non-woven fabric which is coated or transferred in advance, or two or more non-woven fabrics are laminated and heat-sealed to form a single-layer non-woven fabric. The unit area flow resistance of the skin layer is 3.5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ⁴ . The non-woven fabric is, of course, the same type but it is also possible to use different types.

As the hot melt material, polyester, polyethylene or nylon having a basis weight of 20 to 120 g / m ² is selected.

The second composite sound absorbing structure of the present invention is characterized in that the first invention is further characterized, and it comprises an outer skin layer made of a non-woven fabric of a polymeric material and a matrix layer made of a porous polymer fiber material. A composite sound absorbing structure in which a skin layer of a non-woven fabric is disposed on the incident side of sound, and the skin layer is A non-woven fabric selected from polyester, polyethylene, and nylon with a cross-sectional shape of single fiber of circular or flat shape, equivalent single fiber diameter of 11 to 35 μm, and surface density of 50 to 130 g / m ^2. Obtained by applying or transferring in advance a hot melt material selected from powdery or comb-like (network) shape of 20 to 120 g / m ² and having a unit area flow resistance of 3 .5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ^4, and the matrix layer is a polymeric fiber-based porous material mainly composed of polyester fibers, It is a base material layer having a unit area flow resistance of 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ , and a unit area flow resistance of the obtained composite is 1 × 10 ⁴ to 7 × It is a composite sound absorbing structure adjusted to be 10 ⁴ N · sec / m ⁴ . The skin layer is preferably formed by laminating two or more non-woven fabrics on which a hot melt material such as powdery or comb-like (reticulated) is previously applied or transferred on the back surface and integrated by heat fusion.

The present invention is, for example, a polyester fiber-based sound absorbing material with good sound absorbing performance, which comprises a non-woven fabric to be a skin layer with a single fiber diameter of 11 μm or more, withstands practical use, and meets needs such as weight reduction and space narrowing. In order to make the flow resistance of each of the skin layer, the base material layer, and the composite structure an optimal sound absorber, and various construction fields, including construction machines and automobiles, in the field of application. The present invention can be applied in the field of (1), and can provide a sound absorbing material excellent in sound absorbing characteristics with a thickness reduced as much as possible.

It is the schematic which shows the state which attached the sound absorbing material A to the rigid wall surface P. FIG. It is a perspective view showing the 1st example of the compound sound absorption structure of the present invention. It is a perspective view which shows the 2nd example of the compound sound absorption structure of this invention. (A) Composite sound absorbing structure having a skin layer formed by stacking three non-woven fabrics of the same kind (B) Composite sound absorbing structure having a skin layer formed by stacking two different non-woven fabrics It is a graph which shows the sound absorption performance of samples A and B. It is a graph which shows the sound absorption performance of sample A, B, C1. It is a graph which shows the sound absorption performance of sample B, BC, and BS. It is a graph which shows the sound absorption performance of sample B, C2, and D. It is a graph which shows the sound absorption performance of sample B, B25-3. It is a graph which shows the sound absorption performance of sample B25-3, B25-2.

As described above, Japanese Patent No. 3494332 has already been present as a sound absorbing material composed of the non-woven fabric of the skin layer and the matrix layer. However, the diameter of the single fiber constituting the skin layer is preferably 10 μm or less, preferably 5 μm or less. Certainly, when the fiber diameter is thin, the flow resistance is increased, so it can be said that the sound absorbing performance is relatively improved, but practically, the strength, the durability, the composite production with the base material layer, the processed surface There are many inconveniences, such as being difficult to handle and difficult to handle, and having problems with cost. When the nonwoven fabric of the skin layer is composited with the base material layer by hot melt, the fiber diameter is small, and clogging easily occurs. For this reason, the sound absorption coefficient tends to decrease in the high tone range, and there is a problem that the data is easily changed by a small amount.

The present invention is intended to provide a highly practicable structure as a sound absorbing material, and is excellent in practicality as a non-woven fabric of the skin layer, good in availability, and preferably inexpensive. The sound absorption characteristics can be greatly improved by applying a special method to the surface layer when composited with the base material layer, using a single fiber diameter of 11 to 35 μm, and a superior and inexpensive composite sound absorption It is possible to provide a structure.

That is, the main part of the technology of the present invention is a polyester fiber or a nonwoven fabric having a single fiber diameter of 11 to 35 μm which can withstand practical use, such as good strength, durability, processability and appearance as a skin layer. It is possible to obtain stable sound absorption characteristics from middle to low frequency bands to high frequency bands by devising a method of combining with a base material mainly composed of It is in.

In order to realize that, it is effective to first pay attention to the flow resistance of the skin layer and to control this, preferably the flow resistance of the composite structure of the skin layer and the base material is 1 × 10 ⁴ to 7 × ¹⁰ 4 is N · sec / ^{m 4,} particularly draws excellent sound absorbing performance in a wide band, preferably the flow resistance of the complex ^{2 × 10 4 ~ 3.5 × 10} 4 N · sec / m 4 It has been found that it is extremely effective to achieve the object to achieve the object, and the present invention has been made. As a sound absorbing material, the flow resistance when made into a composite is important, but even in that case, it is more effective to improve the sound absorbing performance by adjusting the flow resistance in the skin layer.

When the flow resistance of the composite becomes smaller than 1 × 10 ⁴ N · sec / m ⁴ , the high range is maintained, but the sound absorption performance in the low range is considerably reduced, conversely, 7 × 10 ⁴ N · sec / When the value is larger than m ^4, the sound absorption performance of the high-pitched range is considerably reduced, and it tends to exhibit irregular sound absorption characteristics. And preferably, it is preferable to adjust to 2 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ^4, and when the flow resistance of the composite is less than 2 × 10 ⁴ N · sec / m ⁴ There is a tendency for the sound absorption performance in the low range to slightly decrease, and when it exceeds 3.5 × 10 ⁴ N · sec / m ⁴ , the sound absorption performance in the low range improves but the sound absorption in the high range tends to deteriorate .

In the following, the points of the invention and the means for adjusting the flow resistance are described.
(Point 1)
The constituent material of the invention is mainly a polyester fiber material, which exhibits a novel, wide band and excellent sound absorbing performance, is highly practical in strength, durability, economy and the like, and is recyclable, environmental protection, safety And so on. The same effect can be obtained with other polymer fiber materials such as polyethylene and nylon.

(Point 2)
The basic configuration of the invention is a sound absorbing structure in which a skin layer (spun-bonded non-woven fabric) and a base material are heated and pressed through a hot melt material (hower-like, spider-like, etc.) to form a composite.

(Point 3)
From the practical point of surface strength, durability, easiness of processing and manufacturing, appearance, etc., the spunbonded nonwoven fabric constituting the skin layer is one having a single fiber diameter or an equivalent single fiber diameter of 11 to 35 μm, The practicality is particularly high around 15 μm. If the fiber diameter is 10 μm or less, it is thin, and wrinkles etc. are easily generated when combined with the base material layer, and handling and processability are not good, and if it exceeds 35 μm, the nonwoven fabric feels fluffy and the base material The rigidity after compounding with the layer is increased, and the adaptability becomes worse when being made to follow a curved surface part or the like.

(Point 4)
In the prior art, it is said that the use of the spunbond nonwoven fabric of (point 3) is disadvantageous in terms of sound absorption performance in the prior art, and the present invention uses the following two means to the skin layer disposed on the sound incident side We found that it can be solved by adjusting the flow resistance as a composite sound absorbing structure including a base material, and the flow resistance is preferably set to 2 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ . By adjusting, it has been demonstrated that a composite sound absorbing structure having excellent sound absorbing properties in a wide frequency band can be provided.

Flow resistance adjustment means 1
As a skin layer, a polymeric hot melt material with a basis weight (weight per unit area) of 20 to 120 g / m ² is applied or transferred to the back of one spun bond nonwoven fabric and disposed on the base material layer, Heat and pressure are adjusted to adjust the integrated combined flow resistance to a desired value.

Flow resistance adjustment means 2
Two or more spun bond non-woven fabrics are laminated as a skin layer, placed on a base material layer, heated and pressed, and integrated so that the flow resistance after combined becomes a desired value.
The plurality of spunbonded nonwoven fabrics may have the same specifications or may have different specifications in combination. For example, the number of two spunbond nonwoven fabrics on the top of the skin layer is a fiber whose cross section is circular (area density 100 g / m ² , single fiber diameter 15 μm), and the second spunbond nonwoven fabric is a fiber Two different spunbond non-woven fabrics having a flat cross section (area density 90 g / m ² , equivalent single fiber diameter 14.5 μm) superimposed on a base material, heated and pressed, and composited; If the composite sound absorbing structure has a value of 2.7 × 10 ⁴ N · sec / m ⁴ , excellent sound absorbing performance can be obtained in a wide frequency band. In addition, when using multiple sheets of nonwoven fabric as a skin layer, it is needless to say that fiber diameters other than those specified in the present invention can be used as nonwoven fabrics other than the skin layer.

FIG. 1 shows a state in which a sound absorbing material A made of a porous material is attached to a hard wall surface P. As shown in FIG. Reference numeral 1 denotes a skin layer, 2 denotes a base material layer, and 3 denotes a hot melt material for integrating the two. When sound waves are incident from the left side (skin layer 1 side) of FIG. 1, the velocity of the air particle is 0 at the hard wall P and c / 4f (c: sound velocity in air (cm / sec), f from the hard wall P to the left) : The frequency of the incident sound wave is maximum at a distant position [Hz]). However, in the 500 to 2000 Hz band, where noise is a real problem, the velocity of the air particles is maximum at 40 mm or more, so adjusting the flow resistance with the skin layer 1 up to about 40 mm thick is more viscous By the resistance, the conversion efficiency from acoustic reflection energy to heat energy becomes high, and the sound absorption performance can be efficiently enhanced.

One of the methods of controlling the flow resistance of the skin layer 1 according to the present invention is a sound absorbing material shown in FIG. 2, which is a single layer non-woven fabric used for the skin layer 1, that is, the cross section of single fiber is circular or flat. With an equivalent single fiber diameter of 11 to 35 μm and a surface density of 50 to 130 g / m ² , more preferably 80 to 100 g / m ² , such as powdery or comb-like (reticulated) The hot melt material 3 is previously applied or transferred, and the flow resistance as the skin layer is a combination such that 3.5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ⁴ .

The base material layer 2 is a non-woven fabric mainly composed of polyester fibers, and has a flow resistance of 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ .

For example, a hot melt material such as powdery or comb-like (mesh) shape is applied or transferred in advance to the back surface of the non-woven fabric, and the application or transfer amount is adjusted with a fabric weight of 20 to 120 g / m ² It will be.

In the present embodiment, the skin layer 1 and the base material layer 2 are stacked via the hot melt material 3, heated and pressed, and the two are thermally fused to form an integral composite, and the flow resistance as a composite is 1 × 10 ⁴ It is a sound absorbing structure set to 7 to 10 × 10 ⁴ N · sec / m ⁴ . In order to obtain sound absorption performance in a wide frequency range, the flow resistance may be adjusted to 2 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ .

In addition, another method of controlling the flow resistance of the skin layer is, as shown in FIG. 3, a flow resistance of 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ . The back surface of a base material layer 2 made of a polymer fiber-based porous material and a non-woven fabric 1 having a single fiber with a circular or flat cross section and an equivalent single fiber diameter of 11 to 35 μm and a surface density of 50 to 130 g / m ² 2 or more sheets (in the example shown in FIG. 3 (A), the same non-woven fabric as described in FIG. 2 is used). The flow resistance of the skin layer 1 is 3.5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ⁴ when the sheets (1a, 1b, 1c) are stacked and integrated by heat fusion into multiple layers. It is a non-woven fabric adjusted. Then, the two are stacked, heated and pressurized, and heat fusion integrated into a composite, so that the flow resistance as the composite is 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ to increase the sound absorption coefficient. Sound absorption structure. Of course, also in the present embodiment, the surface layer 1 is used on the sound incident side.

In addition, it is also possible to use different types of non-woven fabrics as the skin layer 1, and the composite shown in FIG. 3B uses the same non-woven fabric 1a as the non-woven fabric described in FIG. As an example 1d, one having a flat cross section, an equivalent single fiber diameter of 11 to 35 μm, and an area density of 50 to 130 g / m ² and using the same hot melt treatment on the back surface is used.

In any of the methods, it is a new discovery that higher sound absorbing performance can be obtained by applying the skin layer to the surface having high density when there is a density gradient in the base material. Also, in actual use, it goes without saying that the surrounding side can be surrounded with a non-woven fabric in order to prevent the infiltration of rain water etc. In this case, heating and pressing through a hot melt film etc. A double-sided adhesive sheet may be used instead of the hot melt film.

(Sound absorption test 1)
It proves mainly that the sound absorption performance of the composite sound absorption structure of the present invention is effective.

Sound absorbing structure A composed only of matrix layer 2 (bulk density 44 kg / m ³ , thickness 35 mm, flow resistance 1 × 10 ⁴ N · sec / m ⁴ ) composed of polyester fiber, and the product of the present invention Using a spunbond non-woven fabric (area density 100 g / m ² ) 1 composed of a polyester fiber system having a single fiber diameter of about 15 μm, and applying a powdery hot melt material (20 g / m ² basis weight) on the back side; The composite sound absorbing structure B (flow resistance: 1.5 × 10 ⁴ N · sec / m ⁴ ) is shown in comparison with the base material layer 2 of (1) by overlapping, heating and pressurizing, and integrated.

FIG. 4 is a graph showing the sound absorption performance of the two samples A and B described above.
Even in the case of the product B of the present invention, even when using a polyester fiber non-woven fabric having a fiber thickness of 15 μm which is practically sufficient for single fiber diameter, it is appropriately treated and composited with an appropriate matrix layer 2 It proves that it is possible to obtain a large sound absorption performance if it is done.
This sound absorbing performance is, for example, comparable to glass wool (bulk density 32 kg / m ³ , thickness 40 to 50 mm) which is normally used as a sound absorbing material. The sound absorption performance is shown by the measurement by the normal incidence method (ISO 10543 · 2).

In FIG. 5, the powdery hot-melt material of sample B shown in FIG. 4 is doubled in weight (40 g / m ² basis weight) and one sample of sample A is composited, and the flow resistance of the composite is 3 The sound absorption performance of the composite sound absorption structure C1 with 2 × 10 ⁴ N · sec / m ⁴ is shown by comparison, but the sound absorption performance in the middle and low frequency bands is significantly improved compared to Sample A. I understand.

As described above, even if the polyester fiber spunbond non-woven fabric 1 having a single fiber diameter of 15 μm is used, the flow resistance of the composite sound absorbing structure is 3 × 10 ⁴ N · sec / m by the application amount of the hot melt material on the back surface. ^By adjusting to around ⁴ , excellent sound absorption characteristics can be obtained in a wide frequency band. Of course, if the flow resistance is further increased, it is also possible to shift to the low frequency side. Thus, the present invention demonstrates the superiority, flexibility, and applicability of the present invention which is extremely practical and still provides excellent sound absorption performance.

(Sound absorption test 2)
It is mainly proved that the sound absorbing performance of the composite sound absorbing structure in which two or more skin layers 1 closest to the sound incident side are stacked and integrated by heating and pressing is effective.

In order to improve the sound absorption performance in the middle and low frequency bands while maintaining the sound absorption performance in the high frequency band further than the sample B in FIG. 4, the flow resistance of the composite sound absorption structure is adjusted. The skin layer 1 and the base material layer are more than inserting the spunbond non-woven fabric 1 (the same as the skin layer 1 of sample B and the same hot melt treatment) in the middle of the base material layer 2 even with almost the same flow resistance. It is shown that it is more effective to insert between the two and increase the flow resistance of the skin layer 1.

In FIG. 6, sample BC is a composite sound absorbing structure in which the same spunbond nonwoven fabric as the skin layer is inserted in the center of the base material of sample B, and the flow resistance of the composite is 2.0 × 10 ⁴ N · sec / m It was ^four . Sample BS is a composite sound absorbing structure in which the same spunbond non-woven fabric as the skin layer is inserted between the surface layer of sample B and the base material, and the two sheets are laminated, and the flow resistance of the composite is 2.2 × It was 10 ⁴ N · sec / m ⁴ .

(Sound absorption test 3)
Further, the effectiveness of the present invention is illustrated in FIG. The same spunbonded nonwoven fabric between the spunbonded nonwoven fabric and the base material layer 2 of the skin layer 1 of the sample B (hot-melt treatment on the back surface) to improve the sound absorption characteristics of the wide frequency band of the sample B shown in FIG. The same applies to two sheets inserted and stacked, heated and pressurized to form a composite sound absorbing structure C2, and its flow resistance is set to 2.9 × 10 ⁴ N · sec / m ^4. It can be seen that the sound absorption performance is dramatically improved in a wide frequency band, demonstrating the effectiveness of the method of the present invention.

Also, the composite sound absorbing structure D is a structure in which four sheets of the same spunbond non-woven fabric are inserted and the flow resistance as the composite sound absorber is 3.9 × 10 ⁴ N · sec / m ^4. Although the performance is improved, the sound absorption coefficient in the band of 630 Hz or higher tends to decrease.

Therefore, the adjustment range of the flow resistance as a practical composite sound absorbing structure is 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ , and 2 × 10 ⁴ to improve sound absorbing performance in a wide band. It is desirable that the value be 3.5 to 10 ⁴ N · sec / m ⁴ . However, in order to improve the sound absorption performance at a specific frequency, for example, 400 Hz or less or 2 kHz or more, the flow resistance may be adjusted in the range of 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ . That is, the flow resistance is increased to improve the low frequency sound absorption performance, and the flow resistance is decreased to improve the high frequency sound absorption performance. This is true of the other method described above. In any case, with the two methods of the present invention, an appropriate base material can be selected, and thereafter, the skin layer can adjust the flow resistance of the composite sound absorbing structure to provide a sound absorbing material having appropriate sound absorbing performance. became.

(Sound absorption test 4)
In the sound absorption test 1, a composite sound absorption structure is formed by adjusting the flow resistance with the application amount of the hot melt material for compounding with the base material on the back surface of one spun bond nonwoven fabric forming the skin layer of the present invention In 2 and 3, two or more spunbond non-woven fabrics (on the back surface coated with a hot melt material) that form the skin layer are laminated on the base material to form a composite sound absorbing structure with flow resistance adjusted. In particular, if the flow resistance of the composite sound absorbing structure is adjusted to 2 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ , excellent sound absorbing performance can be obtained in a wide range from low frequency band to high frequency band. Revealed that This is because, as shown in FIG. 8, the sample B according to the present invention, which is an example of the present invention, is comparable to the commonly used glass wool (bulk density 32 kg / m ³ , thickness 40 to 50 mm). Composite sound absorbing structure sample B25-3 (flow resistance 2.6) obtained by overlapping the skin layer with three same spunbond nonwoven fabrics on the same base material (thickness 25 mm) as sample B by applying one of the methods described above Sound absorption performance equal to or higher than 10 ⁴ N · sec / m ⁴ ) can be obtained, which can be said to show a great advantage of the present invention. This will be able to provide sound absorbing materials with a good space factor, and will also meet the needs of society.

(Sound absorption test 5)
The same spunbond nonwoven fabric of the skin layer as sample B25-3 shown in FIG. 8 on the first skin (area density: 100 g / m ² , single fiber diameter: circular 15 μm), span of a specification different from the second sheet A composite non-woven fabric (surface density: 90 g / m ² , equivalent single fiber diameter: flat shape 14.5 μm) is stacked, and a composite sound absorbing structure B 25-is formed of the two spun bond non-woven fabrics and the same base material as sample B 25-3. 2 was formed. As shown in FIG. 9, the flow resistance of the sample B25-3 and the sample B25-2 as a composite sound absorbing structure is adjusted to 2.6 × 10 ⁴ N · sec / m ⁴ as the former, By adjusting the latter to approximately the same 2.7 × 10 ⁴ N · sec / m ⁴ , the two can obtain approximately the same sound absorption performance (the latter slightly exceeds), and different spunbond nonwoven fabrics as the skin layer By combining the two, it is possible to provide a sound absorbing material which is even more superior to the sample B25-3 even with two spunbonded nonwoven fabrics. This not only excels in practical strength and sound absorption performance in a wide frequency band, but also contributes to economy.
The material used in the present invention is excellent in recyclability and environment because both the skin layer and the base material use a polyester fiber system as a standard.

The present invention can provide a highly practical sound absorbing material having a thin thickness, a wide band, and high sound absorbing performance as compared with the conventional porous sound absorbing material. In addition, the composite sound absorbing structure of the present invention is superior in weight reduction, recyclability, economy, environmental conservation, etc., and has high versatility, so it can be used in construction machinery, agricultural machinery, pneumatic machinery and other industries. It can be used in a wide range of fields, including civil engineering, such as fields, railways, roads, and various construction works, construction fields, and home appliances.

Claims (17)

1. What is claimed is: 1. A composite sound absorbing structure comprising: a skin layer in which one or more non-woven layers of a polymeric material are laminated; and a matrix layer mainly composed of a porous polymer fiber material.
2. The composite sound absorbing structure according to claim 1, wherein the non-woven polymeric material used for the skin layer is polyester, polyethylene or nylon.
3. The composite sound absorbing structure according to claim 1, wherein the porous polymer fiber material of the matrix layer is a polyester fiber.
4. The composite sound absorbing structure according to claim 1, wherein the orientation of the polymeric fiber-based porous material of the matrix layer is any of longitudinal orientation, transverse orientation, or random orientation.
5. The base material layer is composed mainly of polyester fiber, melt fiber having a melting point at 100 to 200 ° C. and appropriately mixed one having a fiber diameter of 2 to 20 denier to have an area density of 500 to 2500 g / m ² integrally. The composite sound absorbing structure according to claim 1, which is molded.
6. The composite sound absorbing structure according to claim 1, wherein the unit area flow resistance of the base material layer is 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m ⁴ .
7. The composite sound absorbing structure according to claim 1, wherein the cross-sectional shape of the single fiber of the non-woven fabric used for the skin layer is circular or flat, the equivalent single fiber diameter is 11 to 35 μm, and the surface density is 50 to 130 g / m ² .
8. The composite sound absorbing structure according to claim 1, wherein the skin layer is a single layer non-woven fabric in which a powdery, honeycomb or network hot melt material is previously applied or transferred on the back surface.
9. 8. The composite sound absorbing structure according to claim 7, wherein the outer skin layer is a single layer non-woven fabric having a powdery, comb-like or reticulated hot melt material applied or transferred on the back side in advance.
10. The composite sound absorption according to claim 1, wherein the skin layer is formed by laminating two or more sheets of non-woven fabric on the back surface of which a powder-like, spider-like or network-like hot melt material is applied or transferred in advance. Structure.
11. The composite sound absorption according to claim 7, wherein the skin layer is formed by laminating two or more sheets of non-woven fabric on the back surface of which a powder-like, spider-like or network-like hot melt material is previously applied or transferred. Structure.
12. The composite sound absorbing structure according to claim 11, wherein the skin layer is a nonwoven fabric of different or the same kind.
13. The composite sound absorbing structure according to claim 1, wherein the unit area flow resistance of the skin layer is 3.5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ⁴ .
14. The composite sound absorbing structure according to claim 1, wherein polyester, polyethylene or nylon having a basis weight of 20 to 120 g / m ² is used as a hot melt material for combining and integrating the skin layer and the base material layer.
15. The composite sound absorbing structure according to claim 1, wherein the unit area flow resistance of the composite of the skin layer and the base material layer is 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ .
16. A skin layer made of a non-woven material of a polymer material and a matrix layer made of a porous material of a polymer fiber are superposed via a hot melt material, heated and pressed, and heat-fused to form an integral composite, non-woven fabric A composite sound absorbing structure in which the skin layer of the air conditioner is disposed on the sound incident side,
    The skin layer is a non-woven fabric selected from polyester, polyethylene, and nylon in which the shape of the single fiber is circular or flat and the equivalent single fiber diameter is 11 to 35 μm, and the surface density is 50 to 130 g / m ² . Obtained by coating or transferring in advance a hot melt material selected from polyester, polyethylene, and nylon in the form of powder, web or net shape with a basis weight of 20 to 120 g / m ^{2 on} the back surface, A skin layer with an area flow resistance of 3.5 × 10 ⁵ to 7 × 10 ⁶ N · sec / m ⁴ ,
    The matrix layer is a polymer fiber based porous material mainly made of polyester fiber, and the unit area flow resistance of this porous material is 0.5 × 10 ⁴ to 3.5 × 10 ⁴ N · sec / m. It is a matrix layer which is ⁴
    A composite sound absorbing structure characterized in that the unit area flow resistance of the obtained composite is adjusted to 1 × 10 ⁴ to 7 × 10 ⁴ N · sec / m ⁴ .
17. The skin layer is a skin layer in which two or more non-woven fabrics on which a powder, spider web or mesh hot melt material is previously applied or transferred on the back surface are laminated and integrated by heat fusion. Complex sound absorption structure.

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