JP2010128005A - Composite sound absorbing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin, lightweight sound absorbing material having high sound absorbing properties in a low frequency region and exhibiting high sound absorbing effect even with low basis weight. <P>SOLUTION: In the composite sound absorbing material produced by sticking a facing material composed of a laminate nonwoven fabric containing at least one very thin fiber layer and a base material composed of staple fiber nonwoven fabric with a mean apparent density of 0.4-0.8 g/cm<SP>3</SP>to each other, adhesiveness between the facing material and the base material is 0.1 N/10 mm or higher while acoustic absorptivity at a frequency of 1,000 Hz is 50% or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a composite sound-absorbing material, and more particularly to a sound-absorbing material having excellent sound-absorbing properties for low-frequency noise represented by driving sounds of automobile engines and construction machinery engines.

  Conventionally, glass wool, rock wool, aluminum fibers, porous ceramics, waste cotton, and the like have been used as sound absorbing materials in interiors of automobiles and houses. However, since these sound absorbing materials have problems in terms of workability, obstacles to the human body, recycling, and environment, various sound absorbing materials using nonwoven fabrics have been proposed in recent years.

For example, Patent Document 1, soundproofing sheet materials have been proposed density using meltblown microfibrous non-woven fabric of 0.013~0.05g / cm ^3. However, this sheet material is prone to thickness deformation, is inferior in handleability, and has problems such as insufficient heat resistance.

Patent Document 2 proposes a sound-absorbing material having flame retardancy, which is composed of two or more kinds of mixed cotton fibers having a melting point difference. However, this sound-absorbing material is excellent in flame retardancy and recyclability. However, since the density is 0.01 to 0.1 g / cm ³ , thickness deformation is likely to occur and there is a problem in handling properties.

Patent Document 3, the fiber diameter contained the following ultrafine fibers 6 [mu] m, and a basis weight of 30 to 200 g / m ² nonwoven, fiber diameter is the basis weight in 7~40μm short fiber nonwoven fabric of 50 to 2000 g / m ² A sound absorbing material integrated by a fluid entanglement method or a needle punch method has been proposed. However, when the integration process is performed by such a method, there is a disadvantage that the ultrafine fibers are cut and a hole is formed, and the sound absorption and form stability are likely to be lowered.

Patent Document 4 discloses a melt blown nonwoven fabric having an average fiber diameter of 10 μm or less, an average apparent density of 0.1 to 0.4 g / cm ³ and a basis weight of 5 to 30 g / m ² , and an apparent density of 0.01 to 0.00. A sound-absorbing material composed of a fiber assembly having a weight of 10 g / cm ³ and a basis weight of 50 to 2000 g / m ² has been proposed. However, this sound-absorbing material has a low strength on the surface of the meltblown nonwoven fabric, and has problems in form stability and handleability.

Further, Patent Document 5, comprising the following ultrafine fibers having a fiber diameter of 6 [mu] m, and melt blown non-woven fabric of a basis weight of 20 to 100 g / m ^2, fiber diameter 7～40Myuemu, basis weight is 50 to 2000 g / m ² and thickness 5 There has been proposed a sound absorbing material in which a 30 mm short fiber nonwoven fabric with a base fabric is laminated and integrated. However, even this sound-absorbing material has low strength on the surface of the melt-blown nonwoven fabric, and there are problems in form stability, handleability and price.

Patent Document 6 describes a sound-absorbing material composed of a surface material composed of a laminated nonwoven fabric of a meltblown ultrafine fiber layer and a synthetic fiber layer and a back material having a rough structure. There is no description.
In contrast to such conventional techniques, there is a demand for a thin and light-weight sound-absorbing material that has a high sound-absorbing property in a low-frequency region and has a high sound-absorbing effect even with low weight.

Japanese Patent Laid-Open No. 06-212546 Japanese Patent Laid-Open No. 10-268871 JP 2001-279567 A JP 2002-69824 A JP 2002-161464 A JP 2006-28708 A

  An object of the present invention is to solve the above-described problems of the prior art, and to provide a thin and lightweight sound absorbing material that has high sound absorption in a low frequency region and has a high sound absorption effect even with low weight. Specifically, it is to provide a sound absorbing material having a high sound absorbing property in a low frequency region of 500 to 1500 HZ.

  As a result of intensive studies on the above problems, the present inventors have found that a composite sound-absorbing material in which a specific face material and a specific base material are combined can obtain high sound-absorbing properties in a low-frequency region, and have reached the present invention. . That is, the present invention provides the following inventions.

(1) Composite sound absorption formed by bonding a face material made of a laminated nonwoven fabric including at least one ultrafine fiber layer and a base material made of a short fiber nonwoven fabric having an average apparent density of 0.4 to 0.8 g / cm ^3. A composite sound-absorbing material, characterized in that an adhesive force between the face material and the substrate is 0.1 N / 10 mm or more, and a sound absorption coefficient at a frequency of 1000 HZ is 50% or more.
(2) The composite sound-absorbing material according to the above item 1, wherein the laminated nonwoven fabric is made of thermoplastic fibers having an average fiber diameter of 10 to 30 μm and includes at least one thermoplastic fiber layer having a basis weight of 40 to 100 g / m ² .
(3) The composite sound-absorbing material as described in 1 or 2 above, wherein the ultrafine fiber layer is made of ultrafine fibers having an average fiber diameter of 0.1 to 5 μm and has a basis weight of 3 to 30 g / m ² .
(4) The composite sound absorbing material according to any one of the above items 1 to 3, wherein the laminated nonwoven fabric is integrated by thermocompression bonding.
(5) the thickness of the face material is 0.1 to 0.3 mm, composite sound absorbing material according to any one of the above 1 to 4, wherein the basis weight is 50 to 120 / m ^2.
(6) The composite sound-absorbing material according to any one of 1 to 5 above, wherein the base material is a mixed fiber of polyester short fibers having an average fiber diameter of 10 to 30 μm and low melting point short fibers.
(7) The composite sound-absorbing material according to any one of 1 to 6 above, wherein the base material has a thickness of 20 to 50 mm and a basis weight of 500 to 1500 g / m ² .
(8) The composite sound-absorbing material according to any one of the above 1 to 7, wherein the face material and the base material are bonded by applying 5 to ²⁰ g / m ^{2 of} a hot melt adhesive.
(9) The composite sound absorbing material according to any one of the above items 1 to 8, wherein the water repellency of the composite sound absorbing material is 50 or more.
(10) The composite sound absorbing material according to any one of 1 to 9 above, wherein the flame retardant property of the composite sound absorbing material is self-digestible.

  The composite sound-absorbing material of the present invention has a high sound-absorbing property in a low frequency region of 400 to 1500 HZ. Therefore, a high sound absorption property can be obtained for noise in a low frequency region generated by a motor which is a member of an automobile, a household appliance, a construction machine, or the like.

In the composite sound-absorbing material of the present invention, the first feature is that the laminated nonwoven fabric having at least one ultrafine fiber layer is used as a face material, so that the sound-absorbing property slides in the low-frequency region, and the sound-absorbing property in the low-frequency region It is to improve.
The face material used in the present invention is made of a laminated non-woven fabric containing an ultrafine fiber layer, converts sound vibration energy into heat energy, and has the effect of sliding the sound absorption suitability region to a low frequency region.

The second feature is that it has a good sound absorbing property in a low frequency region by using a base material having a dense fiber structure.
The base material used in the present invention is formed from a short fiber nonwoven fabric having an average apparent density of 0.4 to 0.8 g / cm ³ , and high sound absorption is obtained in a low frequency region. When a short fiber non-woven fabric is composed of a mixture of polyester short fibers and low melting point short fibers, a thin fiber structure results in a small fiber gap and a high density fiber structure, further improving sound absorption in the low frequency range. Is done.

  The composite sound-absorbing material of the present invention is a combination of the above-described base material having a high sound-absorbing property in a lower frequency region and a face material having an effect that the sound-absorbing suitability region slides in the low-frequency region. High sound absorption is achieved.

The face material constituting the composite sound-absorbing material of the present invention comprises a laminated nonwoven fabric having at least one ultrafine fiber layer.
The average fiber diameter of the ultrafine fibers constituting the ultrafine fiber layer is preferably 0.1 to 5 μm, and more preferably 0.3 to 4 μm. The basis weight of the ultrafine fiber layer is preferably ³ to 30 g / m ² , more preferably 5 to 25 g / m ² . The ultrafine fiber layer constituting the laminated nonwoven fabric is effective for reducing the fiber gap of the laminated nonwoven fabric and converting sound vibration energy into thermal energy to obtain high sound absorption.

The ultrafine fiber layer used in the present invention is preferably formed by a melt blow method.
As the polymer for producing the ultrafine fiber layer, a synthetic resin having a low viscosity and capable of forming ultrafine fibers by a melt blow method is used. For example, polyolefins such as low density polyethylene, high density polyethylene, polypropylene, copolymer polyethylene and copolymer polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate, phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol and 1,4 An aromatic polyester copolymer obtained by copolymerizing one or more compounds of butanediol, poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, and D-lactic acid A biodegradable product comprising a copolymer of L-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or a blend thereof. Polyester, such as aliphatic polyester Such as beauty copolyamide is used.

The laminated nonwoven fabric used in the present invention can contain a thermoplastic synthetic fiber layer in addition to the ultrafine fiber layer.
As for the fiber diameter of the thermoplastic synthetic fiber which comprises a thermoplastic synthetic fiber layer, 10-30 micrometers is preferable, More preferably, it is 12-25 micrometers. The basis weight of the thermoplastic synthetic fiber layer is preferably 40 to 100 g / m ² , more preferably 45 to 90 g / m ² .
Lamination | stacking of a microfiber layer (M layer) and a thermoplastic synthetic fiber layer (S layer) can be selected from multilayered structures, such as SM, SMS, and SMSMS.
The fibers constituting the thermoplastic synthetic fiber layer are formed by a melt spinning method, preferably a spunbond method.

  As the polymer for producing the thermoplastic synthetic fiber constituting the thermoplastic synthetic fiber layer, a synthetic resin having a high viscosity and capable of being fiberized by a melt spinning method is used. For example, polypropylene, copolymerized polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate are copolymerized with one or more compounds of phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol, and 1,4-butanediol. Aromatic polyester copolymer, poly D-lactic acid, poly L-lactic acid, copolymer of D-lactic acid and L-lactic acid, copolymer of D-lactic acid and hydroxycarboxylic acid, L-lactic acid and hydroxy Copolymers with carboxylic acids, copolymers of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or polyesters such as biodegradable aliphatic polyesters composed of blends thereof, and copolyamides are used. It is done. In particular, polyester excellent in heat resistance and water resistance is preferably used.

  Furthermore, in order to maintain good adhesion between the face material and the base material, the layer in contact with the base material can have a low melting point fiber configuration. For example, the low melting point fibers include polyolefin fibers such as low density polyethylene, high density polyethylene, polypropylene, copolymer polyethylene and copolymer polypropylene, and polyethylene terephthalate to phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol and 1, A fiber made of an aromatic polyester copolymer obtained by copolymerizing one or two or more compounds selected from 4-butanediol is preferably used.

Each nonwoven fabric constituting the laminated nonwoven fabric of the present invention is preferably integrated by thermocompression bonding. For example, it is preferable to join by heating and pressure bonding between a known embossing roll and a smooth roll. For example, the heating temperature is preferably in the range of 20 to 150 ° C. lower than the melting point, and for the purpose of alleviating the effects of fiber degradation and roll fusion, a temperature difference can be provided between the upper and lower rolls for thermocompression bonding. The pressure during thermocompression bonding is preferably 10 to 1000 kPa / cm, and more preferably 50 to 700 kPa / cm.
A relatively dense laminated nonwoven fabric can be obtained by partial thermocompression bonding.

The thickness of the laminated nonwoven fabric used in the present invention is preferably 0.1 to 0.3 mm, more preferably 0.12 to 0.27 mm, and the basis weight is preferably 50 to 120 g / m ² , more preferably 60 to 110 g. / M ² . The thickness is less than 0.1 mm, if the basis weight is less than 50 g / m ^2, the strength of the reinforcing material is lowered. On the other hand, when the thickness exceeds 0.3 mm and the basis weight exceeds 120 g / m ² , the strength of the reinforcing material increases, but the bonding processability decreases and the adhesive strength decreases.

  The laminated nonwoven fabric used in the present invention is effective as a reinforcing material for a sound absorbing material, and can be processed to impart surface functions such as black printability, water repellency and flame retardancy. Specifically, coloring processing such as dyeing and printing, water-repellent processing using a fluorine resin, and flame-retardant processing using a flame retardant such as a phosphorus-based material.

The substrate used in the present invention, the average apparent density is composed of the short fiber nonwoven fabric of 0.4 to 0.8 g / cm ^3, a relatively fiber density is high, it is possible to hold a certain thickness. Therefore, an air layer that receives sound vibration is formed on the base material, and the single yarn constituting the base material vibrates, so that the vibration energy of the sound can be converted into heat energy.
As for the average fiber diameter of the short fiber used for a base material, 10-30 micrometers is preferable, More preferably, it is 12-25 micrometers. The fiber length is preferably 25 to 90 mm, more preferably 38 to 76 mm.
The base material used in the present invention can be obtained by mechanically interlacing a fiber web opened by a card method or the like with a knee pan machine using a needle needle. Furthermore, heat treatment is performed with a hot press machine or the like for the purpose of planarizing the surface layer and adjusting the thickness.

The average apparent density of the substrate used in the present invention is preferably 0.4 to 0.8 g / cm ³ , more preferably 0.45 to 0.8 g / cm ³ . In particular, in order to obtain low-frequency sound absorption, a relatively thin fiber configuration and a high-density configuration are preferable.
Furthermore, it is more preferable to mix with the low melting point short fibers in order to bond the constituent fibers to form a dense structure. It is preferable to mix 5 to 60% of low melting point short fibers, more preferably 10 to 50%.

The thickness of the substrate used in the present invention is preferably 20 to 50 mm, more preferably 25 to 40 mm, and the basis weight is preferably 500 to 1500 g / m ² , more preferably 550 to 1400 g / m ² . When the thickness is less than 20 mm and the basis weight is less than 500 g / m ² , the low frequency sound absorption is reduced. On the other hand, when the thickness exceeds 50 mm and the basis weight exceeds 1500 g / m ² , the sound absorption at low frequencies is improved, but the space for the sound absorbing material is increased, and the bonding workability, handling properties, and product transportability are reduced. To do.

  Although the raw material of the thermoplastic synthetic short fiber nonwoven fabric which comprises a base material is not specifically limited, From a viewpoint, such as heat resistance and workability, polyester-type short fibers, such as a polyethylene terephthalate, a polypropylene terephthalate, and a polybutylene terephthalate, are preferable.

Low-melting short fibers to be mixed with the base material include a composite fiber having a core-sheath structure in which the sheath is made of polyethylene, polypropylene and copolymer polyester, the core is made of polypropylene and polyethylene terephthalate, etc., polyethylene terephthalate, phthalic acid, isophthalic acid, sebacin A fiber made of an aromatic polyester copolymer obtained by copolymerizing one or more compounds of acid, adipic acid, diethylene glycol and 1,4-butanediol is preferably used.
Furthermore, 5-30% of acrylic fiber, modacrylic fiber, flame retardant kneaded fiber, polyester fiber, etc. can be included in order to impart flame retardancy to the substrate.

  Adhesion between the face material and the substrate used in the present invention can be performed by thermal adhesion or adhesion using an adhesive. As a heat bonding method, heating is performed from the face material side, and the low melting point component of the constituent fibers of the base material is heated to a temperature of 90 to 230 ° C. and bonded using a press machine or the like that softens or melts. Alternatively, from the face material side, preheating is performed with a far-infrared heater, a carbon heater, or the like, and bonding is performed using a heating and pressing device or the like.

  Accordingly, the composite sound-absorbing material of the present invention is reduced in thickness by pressure bonding by bonding, so that the thickness is increased by 2 to 10 mm from the target thickness before bonding and finished to the target thickness after bonding. It is preferable. At this time, it is preferable to press using a spacer or the like for thickness adjustment.

The bonding method using an adhesive is a curtain spray method, a dot method, a screen method, and the like. A hot melt adhesive is applied to the face material in an amount of ² to 30 g / m ^{2 and is} applied by heating from the face material side. The adhesive is softened and melted, and is pressed and bonded with a press machine.

The adhesive force between the face material and the base material is preferably 0.1 N / 10 mm or more, and more preferably 0.2 N / 10 mm to 5 N / 10 mm.
When the adhesive strength is less than 0.1 N, problems such as peeling due to operations such as cutting and transporting the sound absorbing material occur. Therefore, in order to obtain a high adhesive strength, it is preferable to increase the content of the low-melting-point component of the substrate or to provide a low-melting-point component layer on the bonding surface of the face material. Furthermore, it is also preferable to apply a hot-melt adhesive to the face material.

  The composite sound-absorbing material of the present invention is a composite sound-absorbing material that is excellent in winding workability, cutting workability, wrapping and transportability, etc. is there. Therefore, the composite sound-absorbing material of the present invention has little edge sag during handling and the thickness of the entire thickness, and can provide a stable sound-absorbing property after construction.

The composite sound-absorbing material of the present invention has a high sound-absorbing property in a low frequency region of 500 to 1500 HZ. That is, it has a sound absorbing property of 30% or more at a frequency of 500HZ, 50% or more at 1000HZ, and 60% or more at 1500HZ.
Since the sound-absorbing property of the composite sound-absorbing material of the present invention is combined with the face material, the sound-absorbing property slides in the 200 to 300 Hz low frequency region and has a high sound-absorbing property than the sound-absorbing property of the base material alone. Therefore, the combination of the face material and the base material of the present invention provides a synergistic effect for obtaining high sound absorption in a lower frequency region.

  The composite sound-absorbing material of the present invention is a combination of a face material and a base material, is relatively thin and lightweight, and has a high sound-absorbing property. Moreover, it can also be used as a multilayer which combined the base material of 2 or more layers with the base material, and bonded together the base material and the surface layer of 2 or more layers. This makes it possible to obtain even higher sound absorption.

The thickness of the composite sound absorbing material is preferably 20 to 50 mm, more preferably 20 to 40 mm, and the basis weight is preferably 550 to 1600 g / m ² , more preferably 580 to 1500 g / m ² . When the thickness is less than 20 mm and the basis weight is less than 550 g / m ² , the sound absorption in the low frequency region is lowered.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited only to these. Each characteristic value was measured by the following method.
1) Weight per unit area (g / m ² ): Measured according to JIS-L-1906.
2) Average fiber diameter (μm): 500 times magnified photograph was taken with a microscope, the diameter of 10 fibers was measured, and the average value was obtained.
3) Thickness (mm): Measured according to JIS-L-1906. The thickness was measured at three points under a pressure of 10 kPa and indicated by an average value.
4) Average apparent density (g / cm ³ ): Calculated from (weight per unit area) / (thickness) to determine the weight per unit volume.
5) Sound absorption (%): Frequency of 500 to 1500 HZ was measured with a vertical incidence measuring instrument in accordance with JIS-1405.
6) Joining strength: 180 degree peeling between the base material and the face material was measured at three places in the longitudinal direction and the transverse direction with a tensile tester, and the average value was shown.
7) Water repellency: measured according to JIS-L-1092 (spray method) and evaluated according to the following criteria.
1: The surface shows wetness.
2: Shows wetness on half of the surface and small individual wetness penetrates the fabric.
3: The surface shows small individual water droplets.
4: The surface does not wet, but shows adhesion of small water droplets.
5: The surface has wetness or adhesion of water droplets.
8) Flammability: Measured according to JIS-D-1201 automobile interior material standard (horizontal method).

Example 1
Polyethylene terephthalate (melting point: 263 ° C.) was melt-spun at a spinning temperature of 300 ° C. by a spunbond method to form a fiber web A (weight per unit area: 40 g / m ² , average fiber diameter: 15 μm) on a collection net. Next, polyethylene terephthalate (melting point 260 ° C.) is spun at 300 ° C., heated at 320 ° C., and heated at a flow rate of 1000 Nm ³ / hr. A fiber web B (weighing 20 g / m ² , average fiber diameter 2 μm) was laminated. Further, polyethylene terephthalate (melting point 263 ° C.) is melt spun by a spunbond method at a spinning temperature of 300 ° C. on the ultrafine fiber web B to be fiberized, and the fiber web C (weight is 40 g / m ² , average fiber diameter is 15 μm). ) To obtain a three-layer laminated fiber web. The resulting three-layer fiber web partially thermocompression bonding the pair of embossing rolls / flat roll (temperature 230 ° C. / 215 ° C., a pressure 300N / cm), a basis weight of 100 g / m ^2, an average apparent density 0.27g A face material made of a laminated nonwoven fabric having a / cm ³ and a thermocompression bonding rate of 25% was obtained.

Subsequently, the short fiber nonwoven fabric used as a base material was made of a mixed fiber of polyester short fibers and low melting point short fibers. Polyester short fibers (fiber diameter 17 μm, fiber length 51 mm) and copolymer polyester short fibers (melting point 135 ° C., fiber diameter 20 μm, fiber length 38 mm) are mixed in a ratio of 70:30, opened with a card machine, and short. A fiber web was obtained. The obtained short fiber web was mechanically entangled with a needle punch machine to obtain a base material having a thickness of 30 mm and a basis weight of 1000 g / m ² (average apparent density of 0.33 g / cm ³ ).

After applying a polyamide-based hot melt adhesive (melting point 130 ° C.) at 20 g / m ² to the face material, it was heated to 160 ° C. from the face material side with a hot plate press using a 25 mm spacer. The composite sound-absorbing material of the present invention was obtained by bonding the substrate. The obtained composite sound-absorbing material has a thickness of 25 mm, a basis weight of 1120 g / m ² , an average apparent density of 0.45 g / cm ³ , a sound absorption rate of 55% at a frequency of 500 HZ, a sound absorption rate of 94% at a frequency of 1000 HZ, and a frequency of 1500 HZ. The sound absorption coefficient was 88%, and high sound absorption was obtained in the low frequency region. Further, the weight ratio of the face material to the base material was 10%.
The peel strength between the face material and the base material was 1.6 N / cm, and the face material and the base material were not peeled off during the cutting process and the transport process.

(Example 2)
Polyethylene terephthalate (melting point: 263 ° C.) was melt-spun at a spinning temperature of 300 ° C. by the spunbond method, and fiberized to form a fiber web A (weighing 20 g / m ² , average fiber diameter 13 μm) on the collection net. Then, a polyethylene terephthalate (melting point 260 ° C.) at a spinning temperature of 300 ° C., the temperature is 320 ° C., flow rate using a heated air 1000 Nm ³ / hr, the yarn is ejected directly onto the fiber web A in meltblowing method, ultrafine A fiber web B (weighing 15 g / m ² , average fiber diameter 2 μm) was laminated. Further, polyethylene terephthalate (melting point: 263 ° C.) is melt spun by a spunbond method at a spinning temperature of 300 ° C. on the ultrafine fiber web B to be fiberized, and the fiber web C (weight is 20 g / m ² , average fiber diameter is 13 μm). ) To obtain a three-layer laminated fiber web. The obtained three-layer laminated fiber web was partially thermocompression bonded with a pair of embossing rolls / flat rolls (temperature 225 ° C./215° C., pressure 300 N / cm), basis weight 55 g / m ² , and average apparent density 0.25 g. A face material made of a laminated nonwoven fabric having a thermal compression ratio of 25% / cm ³ was obtained.

Subsequently, the short fiber nonwoven fabric used as a base material was made of a mixed fiber of polyester short fibers and low melting point short fibers. Short polyester fibers (fiber diameter 17 μm, fiber length 51 mm) and copolymerized polyester short fibers (melting point 135 ° C., fiber diameter 20 μm, fiber length 38 mm) are mixed in a ratio of 60:40, opened with a card machine, and short. A fiber web was obtained. The obtained short fiber web was mechanically entangled with a needle punch machine to obtain a base material having a thickness of 25 mm and a basis weight of 1000 g / m ² (average apparent density 0.4 g / cm ³ ).

After applying a polyamide-based hot melt adhesive (melting point 130 ° C.) at 20 g / m ² to the face material, it was heated to 160 ° C. from the face material side with a hot plate press using a 20 mm spacer. The composite sound-absorbing material of the present invention was obtained by bonding the substrate. The obtained composite sound-absorbing material has a thickness of 20 mm, a basis weight of 1075 g / m ² , an average apparent density of 0.54 g / cm ³ , a sound absorption of 45% at a frequency of 500 Hz, a sound absorption of 86% at a frequency of 1000 HZ, and a frequency of 1500 HZ. The sound absorption coefficient was 78%, and high sound absorption was obtained in the low frequency region. The weight ratio of the face material to the base material was 5%.
The peel strength between the face material and the base material was 1.8 N / cm, and the face material and the base material were not peeled off during the cutting process and the transporting process.

(Example 3)
A low melting point fiber layer was provided on the adhesive surface of the laminated nonwoven fabric used for the face material.
Polyethylene terephthalate (melting point: 263 ° C.) was melt-spun at a spinning temperature of 300 ° C. by a spunbond method to form a fiber web A (weight per unit area: 40 g / m ² , average fiber diameter: 13 μm) on a collection net. Next, polyethylene terephthalate (melting point 260 ° C.) is spun at 300 ° C., heated at 320 ° C., and heated at a flow rate of 1000 Nm ³ / hr. A fiber web B (weighing 20 g / m ² , average fiber diameter 2 μm) was laminated. Furthermore, on the ultrafine fiber web B, using a two-component spinneret, a composite long fiber web C (with a sheath component made of a copolyester resin (melting point 160 ° C.) and a core component made of polyethylene terephthalate (melting point 263 ° C.) A basis weight of 40 g / m ² and an average fiber diameter of 17 μm) was laminated to obtain a three-layer laminated fiber web. The obtained three-layer laminated fiber web was partially press-bonded with a pair of embossing rolls / flat rolls (temperature 230 ° C./145° C., linear pressure 300 N / cm), basis weight 100 g / m ² , and average apparent density 0.25 g. A face material made of a laminated nonwoven fabric having a thermal compression ratio of 25% / cm ³ was obtained.

Next, a short fiber nonwoven fabric as a base material was made of a mixed fiber of polyester short fibers, low melting point short fibers and flame retardant short fibers. Polyester short fiber (fiber diameter 17 μm, fiber length 51 mm), copolymer polyester short fiber (melting point 135 ° C., fiber diameter 20 μm, fiber length 38 mm) and phosphorus-based flame retardant kneaded flame retardant polyester short fiber (melting point 260 ° C., fiber (Diameter 18 μm, fiber length 51 mm) were mixed at a ratio of 50:25:25, and opened with a card machine to obtain a short fiber web. The obtained short fiber web was mechanically entangled with a needle punch machine to obtain a substrate having a thickness of 35 mm and a basis weight of 1200 g / m ² (average apparent density 0.34 g / cm ³ ).

After applying a polyamide-based hot melt adhesive (melting point 130 ° C.) at 20 g / m ² to the face material, it was heated to 160 ° C. from the face material side with a hot plate press using a 30 mm spacer. The composite sound-absorbing material of the present invention was obtained by bonding the substrate. The obtained composite sound-absorbing material has a thickness of 30 mm, a basis weight of 1320 g / m ² , an average apparent density of 0.44 g / cm ³ , a sound absorption of 60% at a frequency of 500 HZ, a sound absorption of 97 H at a frequency of 1000 HZ, and a frequency of 1500 HZ. The sound absorptivity was 85%, and high sound absorption was obtained in the low frequency region. The weight ratio of the face material to the base material was 8.3%.
The peel strength between the face material and the base material was 2.3 N / cm, and the face material and the base material were not peeled off during the cutting process and the transport process.

Example 4
Water repellent processing was carried out on one side of the laminated nonwoven fabric obtained in Example 1 with a basis weight of 100 g / m ² by a black gravure printing and gravure method (solvent black ink: manufactured by Toyo Ink Manufacturing Co., Ltd., and solvent -Based fluorine-based water repellent: manufactured by Asahi Glass Co., Ltd.). Next, after applying a hot melt adhesive in the same manner as in Example 1, bonding is performed using the same base material as in Example 1, and the face material and the base material are adhered to each other to combine the sound absorption of the present invention. The material was obtained. The obtained composite sound-absorbing material has a thickness of 20 mm, a basis weight of 1079 g / m ² , an average apparent density of 0.54 g / cm ³ , a sound absorption rate of 48% at a frequency of 500 Hz, a sound absorption rate of 88% at a frequency of 1000 Hz and a frequency of 1500 Hz. The sound absorptivity was 77%, and high sound absorption was obtained in the low frequency region. The water repellency of the surface was 4, and as a result of evaluating the flammability, it was self-digesting.
The peel strength between the face material and the base material was 1.6 N / cm, and the face material and the base material were not peeled off during the cutting process and the transporting process.

(Comparative Example 1)
The sound absorption of only the base material of Example 1 was measured. The sound absorption coefficient at a frequency of 500HZ was 20%, the sound absorption coefficient at a frequency of 1000HZ was 40%, the sound absorption coefficient at a frequency of 1500HZ was 60%, and the sound absorption in the low frequency region was low.

(Comparative Example 2)
The sound absorbing property of only the base material of Example 2 was measured. The sound absorption coefficient at a frequency of 500HZ was 16%, the sound absorption coefficient at a frequency of 1000HZ was 34%, the sound absorption coefficient at a frequency of 1500HZ was 53%, and the sound absorption in the low frequency region was low.

(Comparative Example 3)
The sound absorption property of only the base material of Example 3 was measured. The sound absorption coefficient at a frequency of 500HZ was 26%, the sound absorption coefficient at a frequency of 1000HZ was 46%, the sound absorption coefficient at a frequency of 1500HZ was 69%, and the sound absorption in the low frequency region was low.

  Since the composite sound-absorbing material of the present invention has excellent sound-absorbing properties in the low-frequency region, it has high sound-absorbing properties for motor drive parts such as automobiles, construction machines, and home appliances. Therefore, it is suitably used as a sound absorbing material for automobile members, building materials, home appliances, construction machines and the like.

Claims (10)

A composite sound-absorbing material in which a face material made of a laminated nonwoven fabric including at least one ultrafine fiber layer and a base material made of a short-fiber nonwoven fabric having an average apparent density of 0.4 to 0.8 g / cm ³ are bonded together. A composite sound-absorbing material, wherein the adhesive force between the face material and the base material is 0.1 N / 10 mm or more, and the sound absorption coefficient at a frequency of 1000 HZ is 50% or more. The composite sound-absorbing material according to claim 1, wherein the laminated nonwoven fabric is made of thermoplastic fibers having an average fiber diameter of 10 to 30 μm and includes at least one thermoplastic fiber layer having a basis weight of 40 to 100 g / m ² . The composite sound-absorbing material according to claim 1 or 2, wherein the ultrafine fiber layer is made of ultrafine fibers having an average fiber diameter of 0.1 to 5 µm and has a basis weight of 3 to 30 g / m ² .   The composite sound-absorbing material according to any one of claims 1 to 3, wherein the laminated nonwoven fabric is integrated by thermocompression bonding. The thickness of the facing material is 0.1 to 0.3 mm, composite sound absorbing material according to claim 1 having a basis weight is 50 to 120 / m ^2.   The composite sound-absorbing material according to any one of claims 1 to 5, wherein the base material comprises a mixed fiber of polyester short fibers having an average fiber diameter of 10 to 30 µm and low melting point short fibers. The thickness of a base material is 20-50 mm, and a fabric weight is 500-1500 g / m < ² >, The composite sound-absorbing material as described in any one of Claims 1-6. The composite sound-absorbing material according to any one of claims 1 to 7, wherein the face material and the base material are bonded by applying 5 to ²⁰ g / m ^{2 of} a hot melt adhesive.   The composite sound-absorbing material according to any one of claims 1 to 8, wherein the water-repellent property of the composite sound-absorbing material is 50 or more.   The composite sound-absorbing material according to any one of claims 1 to 9, wherein the flame-retardant property of the composite sound-absorbing material is self-digestible.