JP6929167B2 - Composite sound absorbing material - Google Patents

Description

The present invention relates to a composite sound absorbing material. More specifically, the present invention is a composite sound absorbing material in which a non-woven face material and an open cell resin foam layer are bonded, and low frequency to medium frequency, particularly frequencies 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz. The present invention relates to a composite sound absorbing material which is excellent in sound absorbing property, thin, lightweight, and excellent in morphological stability, and is particularly suitable as a sound absorbing material in automobiles, houses, home appliances, construction machinery, and the like.

When a vehicle or the like travels, various noises such as noise from the engine and drive system mounted on the vehicle, road noise during traveling, and wind noise are generated. Sound absorbing materials are used as noise countermeasures on the walls of engine hoods, dash panels, ceiling materials, door trims, cab floors, etc. so that these noises do not cause discomfort to the crew.

As the sound absorbing material, a sound absorbing material made of a porous material such as a non-woven fabric or a resin foam, or a laminated structure in which such a sound absorbing material and a skin layer such as a breathable non-woven fabric or a resin film are laminated and integrated is known. There is.

The following Patent Document 1 discloses a soundproof sheet material using a melt-blown ultrafine fiber non-woven fabric having a bulk density of 0.013 to 0.05 g / cm ^3. However, this soundproof sheet material has problems that the thickness is easily deformed, the handleability is poor, and the heat resistance is insufficient.

The following Patent Document 2 describes a surface material made of a laminated non-woven fabric of a melt-blown ultrafine fiber layer and a synthetic fiber layer, and a back material of a synthetic fiber non-woven fabric having a coarse structure with ^{a bulk density of 0.005 to 0.15 g / cm 3.} Although a sound absorbing material made of the above is disclosed, since fibers having a fiber diameter of 10 to 30 μm are used to roughen the synthetic fiber non-woven fabric as the backing material, the sound absorbing property in the low frequency region is poor.

Similar to Patent Document 2, the following Patent Document 3 includes a surface material made of a laminated non-woven fabric of a melt-blown ultrafine fiber layer and a synthetic fiber layer, and a relatively dense structure ^{having a bulk density of 0.4 to 0.8 g / cm 3.} Although a sound absorbing material made of a synthetic fiber non-woven fabric backing material is disclosed, since the synthetic fiber non-woven fabric backing material has a dense structure, the air permeability is deteriorated and the sound absorbing property in a region higher than the medium frequency is poor.

Similar to Patent Documents 2 and 3, the following Patent Document 4 includes a surface material made of a laminated non-woven fabric of a melt-blown ultrafine fiber layer and a synthetic fiber layer, and a synthetic fiber non-woven fabric ^{having a bulk density of 0.05 to 0.5 g / cm 3.} A sound absorbing material capable of obtaining a high sound absorbing effect for a sound in a relatively wide range of frequencies composed of a backing material is disclosed. However, in the sound absorbing material described in Patent Document 4, in order to improve the sound absorbing rate of a sound having a frequency of 1000 to 4000 Hz, the basis weight of the sound absorbing material ^{needs to be 475 g / m 2} or more and the thickness must be 30 mm or more.
As described above, it has not been possible to achieve both the handleability required for vehicle applications, the sound absorption in a wide frequency range, and the weight reduction only with the porous non-woven fabric material and its laminated structure.

The following Patent Document 5 discloses a sound absorbing material composed of a soft urethane foam as an open-cell resin foamed resin body and a synthetic resin layer having fine pores in the epidermis. However, the resin layer of the epidermis does not contribute to sound absorption, and the denseness of the ultrafine fiber layer cannot be ensured.

The following Patent Document 6 discloses a sound absorbing material composed of a melamine-based resin foam as an open-cell resin foam resin and a film layer having fine pores. However, as in Patent Document 5, such a film layer does not contribute to sound absorption, and the fineness of the ultrafine fiber layer cannot be ensured.

Japanese Patent Application Laid-Open No. 06-212546 Japanese Patent No. 4574262 JP-A-2010-128005 Japanese Patent No. 4919881 Japanese Unexamined Patent Publication No. 2008-146001 JP-A-2010-196421

In view of the above-mentioned problems of the prior art, the problem to be solved by the present invention is to have high sound absorption and low frequency in a wide range of low to medium frequencies, specifically, a frequency range of 1000 to 4000 Hz. It is an object of the present invention to provide a sound absorbing material having a high sound absorbing effect even with a texture, being thin and lightweight, and having excellent morphological stability.

As a result of diligent studies and experiments in order to solve the above problems, the present inventors have obtained a composite sound absorbing material in which a specific non-woven face material and a specific open cell resin foam layer are combined, and the frequency is low to medium. We have found that high sound absorption can be obtained in a wide frequency range, and have completed the present invention.

That is, the present invention is as follows.
[1] A composite sound absorbing material obtained by joining a non-woven fabric surface material containing at least one melt-blown ultrafine fiber layer having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ^{2 and an open cell resin foam layer.} Therefore, the thickness of the composite sound absorbing material is 5 to 50 mm, the texture ^{is less than 50 to 475 g / m 2} , and the sound incident from the non-woven fabric surface material side in the vertical incident measurement method conforming to JIS-1405. The composite sound absorbing material is characterized in that the sound absorbing coefficient of the composite sound absorbing material at frequencies of 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz is 40% or more.
[2] The non-woven fabric facing material has a melt-blown ultrafine fiber layer (M) having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ² and a continuous long fiber layer (S) having an average fiber diameter of 10 to 30 μm. A laminated non-woven fabric having an SM-type or SMS-type laminated structure integrated by thermal pressure bonding, the laminated non-woven fabric having a texture of 20 to 250 g / m ² and an air permeability of 100 cc / cm ² / sec or less. 1] The composite sound absorbing material according to.
[3] When there are two or more non-woven fabric layers constituting the non-woven fabric face material, the layer of the non-woven fabric face material in contact with the open cell resin foam layer is from the melting point of the fibers constituting the other layer of the non-woven fabric face material. The composite sound absorbing material according to the above [1] or [2], which also contains a fiber having a melting point as low as 30 ° C. or higher.
[4] The above-mentioned [1] to [3], wherein the open cell resin foam layer has a thickness of less than 5 to 50 mm and a bulk density of 0.01 to 0.1 g / cm ^3. Composite sound absorbing material.

The composite sound absorbing material according to the present invention is thin, lightweight, and morphologically stable in the low to medium frequency range of 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz, while having high sound absorbing properties. Since it is excellent, it is particularly suitable as a sound absorbing material for automobiles, houses, home appliances, construction machinery, and the like.

Hereinafter, embodiments of the present invention will be described in detail.
In the composite sound absorbing material of the present embodiment, a non-woven fabric surface material containing at least one melt-blown ultrafine fiber layer having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ^{2 is bonded to a continuous cell resin foam layer.} The composite sound absorbing material, the thickness of the composite sound absorbing material is 5 to 50 mm, the texture ^{is less than 50 to 475 g / m 2} , and the non-woven fabric facing material is measured by a vertical incident measurement method based on JIS-1405. The composite sound absorbing material is characterized in that the sound absorption coefficient of the composite sound absorbing material is 40% or more at frequencies of 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz of sound incident from the side.
A preferred non-woven fabric facing material is a melt-blown ultrafine fiber layer (M) having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ² and a continuous long fiber layer (S) having an average fiber diameter of 10 to 30 μm by thermal bonding. It is a laminated non-woven fabric having an integrated SM type or SMS type laminated structure, and the weight of the laminated non-woven fabric is 20 to 250 g / m ² , and the air permeability is 100 cc / cm ² / sec or less.

The first feature of the composite sound absorbing material of the present embodiment is that the non-woven surface material has a very small amount of air permeability and has a dense structure having small fiber voids in terms of fiber structure, and the wavelength of the incoming sound is high. The frictional resistance in the pores reduces the sound and the sound enters the fiber voids, so that the sound absorption characteristics slide into the low frequency region and the sound absorption in the low frequency region is improved. That is, since the non-woven fabric face material of the present embodiment contains at least one ultrafine fiber layer, it has the effect of converting the vibration energy of sound into heat energy and sliding the sound absorption suitability region to the low frequency region.

The second feature of the composite sound absorbing material of the present embodiment is that the sound transmitted through the non-woven surface material is reflected by using the open cell resin foam having a fine skeleton with a specific bulk density together with the non-woven surface material. The sound is efficiently converted into heat energy by easily invading the open cell resin foam without having to enter the body, and when the sound invades, the sound is efficiently converted into heat energy by the friction of the open cell resin foam with the fine skeleton and the vibration of the skeleton. Is Rukoto. The bulk density of the open-cell resin foamed resin body of the present embodiment is preferably 0.01 to 0.1 g / cm ³ .

The average fiber diameter of the fibers constituting the melt blow ultrafine fiber layer (M) contained in at least one layer in the non-woven fabric facing material is 0.3 to 7 μm, preferably 0.4 to 5 μm, and more preferably 0.6 to 2 μm. .. Stable fibers cannot be obtained because harsh conditions are required for spinning to a fiber diameter of less than 0.3 μm by the melt blow method. On the other hand, when the fiber diameter exceeds 7 μm, it becomes close to the average fiber diameter of the fibers constituting the continuous long fiber layer (S) having an average fiber diameter of 10 to 30 μm, and enters the gap of the continuous long fiber layer as fine fibers to fill the gap. Since the filling action is not played, a precise structure cannot be obtained.

In the composite of the non-woven fabric face material and the open-cell resin foam layer having a relatively small density and many voids, the non-woven fabric face material arranged on the sound source side may be denser than the open-cell resin foam layer. Although required, in the method of making the fibers denser by increasing the density by excessive heat bonding on the entire surface, the surface area of the fibers is reduced by heat fusion, and the conversion efficiency into heat energy due to the friction between the sound and the fibers is increased. It will drop. Therefore, it is desirable that the densification of the non-woven fabric facing material is composed of finer fibers.

Basis weight of the meltblown microfiber layer contained at least one layer to the nonwoven surface material, in order to obtain adequate sound absorption in the low basis weight is 1 to 40 g / ^{m 2,} preferably 2~25g / ^{m 2,} more preferably It is 3 to 20 g / m ² .

As the fiber material of the melt blow ultrafine fiber layer (M) and the continuous long fiber layer (S), a thermoplastic synthetic resin that can be fibrized by the melt spinning method is used. Examples of the thermoplastic synthetic resin include polypropylene, copolymerized polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene terephthalate, phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol, and 1,4-butanediol. Aromatic polyester copolymer copolymerized with seeds or two or more compounds, poly D-lactic acid, poly L-lactic acid, copolymer of D-lactic acid and L-lactic acid, D-lactic acid and hydroxycarboxylic acid Polyesters such as copolymers, copolymers of L-lactic acid and hydroxycarboxylic acid, copolymers of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, and biodegradable aliphatic polyesters composed of blends thereof. , Copolymerized polyamide, polyphenylene sulfide and the like. As the thermoplastic synthetic resin, polyester and polyphenylene sulfide having excellent heat resistance and water resistance are particularly preferable.

In the case of PET or a copolymer thereof, the solution viscosity (ηsp / c) of the melt-blown ultrafine fibers is preferably 0.2 to 0.8, more preferably 0.2 to 0.6. Further, the melt-blown fine fibers of PET are slower to crystallize than other synthetic fibers and can penetrate into the gaps of the continuous long fiber layer in a state of low crystal fluidity, so that the fiber gaps of the continuous long fiber layer are filled. It is possible to form a dense structure.

In the preparation of the continuous long fiber layer of the non-woven fabric facing material constituting the composite sound absorbing material of the present embodiment, it is preferable to appropriately set the spinning speed and the like in order to develop sufficient strength by stretching. For example, in the case of PET, it is preferable to perform draw spinning at a spinning speed of 3000 m / min or more. The continuous long fiber layer (web) is preferably prepared by uniformly dispersing the threads by triboelectric charging, corona charging, or the like by the spunbond method. According to such a method, it is easy to form an unbonded web, and it is economically advantageous. Further, the continuous long fiber web may be a single layer or a plurality of layers.
The average fiber diameter of the fibers constituting the continuous long fiber layer is preferably 10 to 30 μm, more preferably 12 to 25 μm, from the viewpoint of covering property, strength, spinning stability and the like.

The shape of the fiber cross section of the continuous long fiber layer and the melt blow ultrafine fiber layer is not particularly limited, but a round cross section is preferable from the viewpoint of strength, and a flat yarn is preferable from the viewpoint of increasing the surface area of the fiber and forming fine voids. Atypical cross-section yarns such as are preferred.

The layer in contact with the open cell resin foam layer in the nonwoven fabric facing material preferably contains fibers having a melting point of 30 ° C. or more lower than the melting point of the fibers constituting the other layer of the nonwoven fabric facing material.
For example, in order to maintain good adhesion between the non-woven fabric face material and the open cell resin foam layer, the layer of the non-woven fabric face material in contact with the open cell resin foam layer may have a low melting point fiber composition. can. Examples of low melting point fibers include polyolefin fibers such as low density polyethylene, high density polyethylene, polypropylene, copolymerized polypropylene, and copolymerized polypropylene, phthalic acid, isophthalic acid, sebacic acid, adipic acid, diethylene glycol, and 1, Examples thereof include aromatic polyester copolymers obtained by copolymerizing one or more compounds of 4-butanediol, polyester fibers such as aliphatic esters, and synthetic fibers such as copolymerized polyamides. These fibers may be used alone, may be a composite blend of two or more kinds, or may be a composite blend of a low melting point fiber and a high melting point fiber. The low melting point fiber preferably includes a composite fiber having a sheath core structure having a low melting point component in the sheath portion, and examples thereof include polyethylene terephthalate, polypropylene terephthalate, copolymerized polyester, and nylon having a high melting point component in the core. 6. Nylon 66, copolymerized polyamide, etc., such as low-density polyethylene, high-density polyethylene, polypropylene, copolymerized polyethylene, copolymerized polypropylene, copolymerized polyester, aliphatic ester, etc., whose sheath is a low melting point component. ..

The non-woven fabric facing material needs to include at least one melt-blown ultrafine fiber layer (M). Without the melt-blown ultrafine fiber layer, it is not possible to form a dense structure with small fiber voids, and the wavelength of the incoming sound becomes smaller due to the frictional resistance in the pores, making it impossible to control the sound absorption characteristics. The non-woven fabric facing material may be composed of one melt blow ultrafine fiber layer (M), or two or more layers such as MM type and MMM type. Further, the SM type or SMS type laminated structure may be formed together with the continuous long fiber layer (S). From the viewpoint of reducing basis weight, it is better to be composed of only melt-blown ultrafine fiber layers such as M layer or MM layer, and from the viewpoint of strength and handleability, continuous long fiber layers such as SM type or SMS type. It is good to have a structure that is laminated with.

Each non-woven fabric layer constituting the non-woven fabric face material is preferably integrated by heat crimping, and for example, it is possible to heat and crimp between a known embossed roll and a smoothing roll, or between a smoothing roll and a smoothing roll to join them. preferable. The heating temperature is preferably, for example, 20 to 150 ° C. lower than the melting point of the fibers existing on the heat-bonded surface, and is set to the heating temperature between the upper and lower rolls in order to further mitigate the effects of fiber deterioration and roll fusion. Differences can also be made. The pressure at the time of thermal pressure bonding is preferably 10 to 1000 kPa / cm, more preferably 50 to 700 kPa / cm. By heat-bonding, a relatively dense laminated non-woven fabric can be obtained.

Woven cloth surface material is preferably 20 to 250 g / ^{m 2,} more preferably from 50 to 200 g / ^{m 2.} If the basis weight is ^{less than 20 g / m 2} , the uniformity and denseness of the non-woven fabric are lowered, and small voids cannot be obtained. On the other hand, when the basis weight ^{exceeds 250 g / m 2} , a dense structure with small voids is obtained, but the rigidity is increased, the cutability and handleability are lowered, and the cost is further increased.

The bulk density of the nonwoven surface material is preferably 0.1~0.7g / cm ^3, more preferably 0.15~0.6g / cm ^3, more preferably 0.2~0.55g / Cm ³ . When the bulk density is high, the filling density of the fibers is high, resulting in a dense structure of small voids. Therefore, if the bulk density is ^{less than 0.1 g / cm 3} , the denseness of the non-woven fabric is lowered, and the effect of reducing sound is lowered. On the other hand, when the bulk density ^{exceeds 0.7 g / cm 3} , the non-woven fabric is too dense, the voids are reduced, the sound penetration is insufficient, and the sound absorption coefficient especially around the medium frequency of 4000 Hz is lowered. Workability is also reduced.

Furthermore, air permeability of the nonwoven surface material, preferably 100cc ^/ cm 2 ^/ sec or less, more preferably 1~50cc ^/ cm 2 ^/ sec or less, more preferably from 0.5~30cc ^/ cm 2 ^/ sec. If the air permeability ^{exceeds 100 cc / cm 2} / sec, the wavelength of the incoming sound cannot be reduced, and the effect of reducing the sound energy cannot be obtained.

The non-woven fabric face material of the present embodiment is effective as a reinforcing material for a sound absorbing material, and can be subjected to a process for imparting surface functions such as printability such as black color, water repellency, and flame retardancy. Specific examples thereof include coloring processing such as dyeing and printing, water repellent processing using a fluorine resin, and flame retardant processing using a flame retardant such as phosphorus.

The bulk density of the open cell resin foam layer ^{is preferably 0.01 to 0.1 g / cm 3} , more preferably 0.02 ^{to 0.08 g / cm 3} , and even more preferably 0.03 to 0.05 g / cm. It is ^3. If the bulk density is ^{less than 0.01 g / cm 3} , the sound absorption property is lowered, so that it is necessary to make the thickness more than necessary. When the bulk density ^{exceeds 0.1 g / cm 3} , it is difficult for the sound transmitted through the non-woven fabric facing material to enter the open cell resin foam, and the sound absorption coefficient at frequencies after 4000 Hz is particularly lowered, and the wear resistance is increased. Workability is also reduced.
In this way, in order to combine the open cell resin foam layer and the non-woven fabric facing material to obtain a sound absorbing material that is thin, lightweight, and has excellent morphological stability while having high sound absorbing properties, the open cell resin is used. It is desirable that the foam layer has a specific bulk density. The bulk density of the open cell resin foam may be compression-adjusted by a known heat press or the like before being combined with the non-woven fabric face material, and is integrally molded with the non-woven fabric face material when thermoforming into an automobile member or the like. The compression may be adjusted accordingly.

The thickness of the open cell resin foam layer is preferably 5 to 50 mm, more preferably 10 to 40 mm. The basis weight of the open cell resin foam layer ^{is preferably 10 to 400 g / m 2} , and more preferably 20 to 300 g / m ² . If the thickness is less than 5 mm and the basis weight is ^{less than 10 g / m 2} , the sound absorption property is insufficient, and the sound absorption rate of particularly low frequency sound absorption is lowered. On the other hand, when the thickness exceeds 50 mm and the basis weight exceeds 400 g / m ² , the sound absorption of low frequencies is improved, but the space of the sound absorbing material is increased, and the laminating workability, handleability, product transportability, etc. are deteriorated. do.

Examples of the material of the open cell resin foam include polyethylene resin, polypropylene resin, polyurethane resin, polyester resin, acrylic resin, polystyrene resin, melamine resin, etc., from the viewpoint of sound absorption, flexibility, light weight, and the like. Soft urethane foam is preferred.

The composite sound absorbing material of the present embodiment is obtained by joining and integrating the above-mentioned non-woven fabric face material (surface material) and the open cell resin foam layer (back surface material) having a coarse structure. For joining the front surface material and the back surface material, for example, a method of interposing a heat-sealing fiber on the joint surface and heat-treating, a method of applying a hot-melt resin or an adhesive and then heat-treating, and a curtain spray method of hot-melt resin. It can be done by the method of applying with.

In the bonding method using an adhesive, a hot melt adhesive is applied to the non-woven fabric surface material at a ratio of ² to 30 g / m 2 by a curtain spray method, a dot method, a screen method, etc., and heated from the non-woven fabric surface material side. Then, the applied adhesive can be softened, melted and adhered.

The adhesive force between the non-woven fabric face material and the open cell resin foam is preferably 0.1 N / 10 mm or more, and more preferably 0.2 N / 10 mm to 5 N / 10 mm. If the adhesive strength is less than 0.1 N / 10 mm, problems such as peeling during cutting and transportation of the sound absorbing material occur. In order to obtain high adhesive strength, it is preferable to provide a low melting point component layer on the adhesive surface of the non-woven fabric facing material, and it is also preferable to apply a hot melt adhesive to the open cell resin foam.

The composite sound absorbing material of the present embodiment has a thickness of 5 to 50 mm and a basis weight of ^{less than 50 to 475 g / m 2} , preferably a thickness of 7 to 45 mm and a basis weight of 60 to 400 g / m ² .

In the method for measuring vertical incidence of the composite sound absorbing material of the present embodiment in accordance with JIS-1405, the sound absorbing coefficient at frequencies of 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz of the sound incident from the non-woven fabric surface material side is any. Is also 40% or more, preferably 50 to 95%, and more preferably 60 to 100%.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention should not be construed as being limited to these. Each characteristic value was measured by the following method.
(1) Metsuke (g / m ² )
Compliant with JIS-1913.
(2) Average fiber diameter (μm)
A 500-fold magnified photograph was taken with a microscope, and the average value of 10 fibers was calculated.
(3) Bulk density (g / cm ³ )
It was calculated from (Metsuke) / (Thickness), and the weight per unit volume was calculated.
(4) Thickness (mm)
It conformed to the JIS-L-1913-B method. The thickness of the pressure with a load of 0.02 kPa was measured at three or more places, and the average value was calculated. However, the thickness of the non-woven fabric facing material was measured under a load of 20 kPa.
(5) Sound absorption coefficient (%)
In accordance with JIS-1405, measurements were made over frequencies of 1000 to 4000 Hz using a vertical incident measuring instrument.
(6) Breathability The measurement was performed by the Frajour method based on JIS-L-1906.

[Example 1]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. On the obtained continuous long fiber web (meshing 20.8 g / m ² , average fiber diameter 13 μm), polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun with a melt blow nozzle at a spinning temperature of 300 ° C and heated air. Direct ejection under the conditions of 320 ° C. and 1000 Nm ³ / hr formed ultrafine fiber webs (M) (meshing 8.4 g / m ² , average fiber diameter 1.7 μm). On the obtained ultrafine fiber web, a continuous long fiber web (S2) of polyethylene terephthalate was formed in the same manner as the fiber web (S1). Next, the obtained laminated web was partially heat-bonded at a pair of embossed roll / flat roll temperature of 230 ° C. and a linear pressure of 30 N / mm, and the texture was 50 g / m ² , the bulk density was 0.22 g / cm ³ , and the partial heat-bonded area ratio. An 11% non-woven fabric facing material was obtained.
As the open cell resin foam layer, a soft urethane foam (manufactured by Achilles Corporation, product type: low ventilation foam, product number: PPK) with ^{a thickness of 30 mm, a grain size of 69 g / m 2} , and a bulk density of 0.023 ^{g / cm 3 is used, and the non-woven fabric surface is used.} Joined with wood. The bonding was carried out by applying a ^{copolymerized polyester hot melt powder (melting point 130 ° C.) at a ratio of 20 g / m 2 to} the non-woven fabric facing material and the open cell resin foam layer, and heat-treating. Table 1 below shows various physical characteristics of the obtained composite sound absorbing material.

[Example 2]
A composite sound absorbing material was obtained in the same manner as in Example 1 except that the partial thermal pressure bonding area ratio of the non-woven fabric facing material ^{was changed to 15% and the bulk density was 0.28 g / cm 3.} Table 1 below shows various physical characteristics of the obtained composite sound absorbing material.

[Example 3]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. On the obtained continuous long fiber web (meshing 20.0 g / m ² , average fiber diameter 13 μm), polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun with a melt blow nozzle at a spinning temperature of 330 ° C and heated air. Direct ejection under 370 ° C. 1300 Nm ³ / hr conditions formed ultrafine fiber webs (M) (mesh 40 g.0 / m ² , average fiber diameter 0.8 μm). On the obtained ultrafine fiber web, a continuous long fiber web (S2) of polyethylene terephthalate was formed in the same manner as the fiber web (S1). The resulting laminated web, the pair of embossing rolls / flat roll temperature of 230 ° C., partially thermocompression bonding at a linear pressure of 30 N / mm, basis weight 80 g / m ^2, bulk density 0.29 g / cm ^3, a thermal compression bonding area ratio of 15% A non-woven fabric face material was obtained.
As an open cell resin foam layer, a soft urethane foam (manufactured by Achilles Co., Ltd., product type: low ventilation foam, product number: PPK) with ^{a thickness of 30 mm, a grain size of 69 g / m 2} , and a bulk density of 0.023 ^{g / cm 3 is hot pressed at 130 ° C.} A material compressed to a thickness of 15 mm and a bulk density of 0.46 g / cm ³ was used and bonded to the non-woven face material. For joining, a copolymerized polyester hot melt powder (melting point 130 ° C.) was applied at a ratio of ^{20 g / m 2 to the non-woven fabric facing material and the open cell resin foam layer.} It was heat-treated. Table 1 below shows various physical characteristics of the obtained composite sound absorbing material.

[Example 4]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. Polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun on the obtained continuous long fiber web ( ^{mesh 15.3 g / m 2} , average fiber diameter 13 μm) with a melt blow nozzle at a spinning temperature of 300 ° C and heated air. Direct ejection under the conditions of 320 ° C. and 1000 Nm ³ / hr formed ultrafine fiber webs (M) (mesh ^{size 9.4 g / m 2} , average fiber diameter 1.7 μm). Next, using a two-component spinneret, a yarn having a sheath component of a copolymerized polyester resin (melting point 160 ° C.) and a core component of polyethylene terephthalate (melting point 263 ° C.) is spun into a continuous long fiber web (S2). (Grasping 15.3 g / m ² , average fiber diameter 13 μm) was formed. The resulting laminated web, the pair of embossing rolls / flat roll temperature 230/145 ° C., partially thermocompression bonding at a linear pressure of 30 N / mm, basis weight 40 g / m ^2, bulk density 0.22 g / cm ^3, a thermal compression bonding area ratio 11 % Non-woven fabric face material was obtained.
As the open cell resin foam, a soft urethane foam (manufactured by Achilles Corporation, product type: low ventilation foam, product number: PPK) with ^{a thickness of 30 mm, a grain size of 69 g / m 2} , and a bulk density of 0.023 g / cm ^{3 is used, and the laminated non-woven fabric is used.} It was joined to the face material by hot pressing. At the time of joining, the open cell resin foam layer was heat-pressed at 150 ° C. so that the thickness was 20 mm and the bulk density was 0.046 g / cm ^3. Table 1 below shows various physical characteristics of the obtained composite sound absorbing material.

[Comparative Example 1]
Various physical properties of the soft urethane foam (manufactured by Achilles Corporation, product type: low-ventilation foam, product number: PPK) with a thickness of 30 mm, a ^{grain size of 69 g / m 2} , and a bulk density of 0.023 ^{g / cm 3 used in Examples 1 and 2.} It is shown in Table 1 below. The soft urethane foam alone had a particularly low sound absorption coefficient at frequencies of 1600 Hz or less.

[Comparative Example 2]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. On the obtained continuous long fiber web (meshing 27.0 g / m ² , average fiber diameter 14 μm), polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun with a melt blow nozzle at a spinning temperature of 300 ° C and heated air. Direct ejection under the conditions of 320 ° C. and 1000 Nm ³ / hr formed ultrafine fiber webs (M) (meshing 16 g / m ² , average fiber diameter 2 μm). On the obtained ultrafine fiber web, a continuous long fiber web (S2) of polyethylene terephthalate was formed in the same manner as the fiber web (S1). The resulting laminated web, the pair of embossing rolls / flat roll temperature of 230 ° C., partially thermocompression bonding at a linear pressure of 30 N / mm, basis weight 70 g / m ^2, a bulk density of 0.20 g / cm ^3, a thermal compression bonding area ratio of 12% A non-woven fabric face material was obtained.
Using 70% of polyester short fibers (fiber diameter 25 μm, fiber length 51 mm) and 30% of copolymerized polyester fibers (melting point 135 ° C., fiber diameter 18 μm, fiber length 51 mm), a web is formed by a known card method, and a needle is formed. It was entangled by punching (NP) processing to obtain a fiber with a grain size of ^{150 g / m 2} , a bulk density of 0.012 g / cm ^{3, and a thickness of 13 mm. This was applied to a non-woven fabric facing material at a ratio of 20 g / m 2} of a copolymerized polyester hot melt powder (melting point 130 ° C.), and bonded by heat treatment. The various physical characteristics of the obtained composite sound absorbing material are shown in Table 1 below. Since the composite sound absorbing material of Comparative Example 2 used a short fiber NP-processed non-woven fabric instead of the open cell resin foam, the sound absorbing coefficient having a frequency of 2000 Hz or less was particularly low.

[Comparative Example 3]
The continuous length fiber webs (S1 and S2) of the non-woven fabric facing material are 21 g / m ² respectively, the ultrafine fiber web (M) is 8 g / m ² , and the partial thermal pressure bonding area ratio is 25%, which is short. A composite sound absorbing material was obtained in the same manner as in Comparative Example 2, except that the texture of the fiber NP-processed non-woven fabric was 450 g / m ² , the bulk density was 0.018 g / cm ^{3, and the thickness was 25 mm.} Table 1 below shows various physical characteristics of the obtained composite sound absorbing material. Compared with Comparative Example 2, the composite sound absorbing material of Comparative Example 3 has improved sound absorption due to the increase in the basis weight and thickness of the short fiber NP-processed non-woven fabric, but the weight of the composite sound absorber is heavy (the basis weight is large). ) It was inferior in lightness.

[Comparative Example 4]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. On the obtained continuous long fiber web (meshing 20 g / m ² , average fiber diameter 13 μm), polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun with a melt blow nozzle at a spinning temperature of 300 ° C and heated air 320. Direct ejection under the conditions of ° C. 1000 Nm ³ / hr formed ultrafine fiber webs (M) (meshing 15 g / m ² , average fiber diameter 2 μm). On the obtained ultrafine fiber web, a continuous long fiber web (S2) of polyethylene terephthalate was formed in the same manner as the fiber web (S1). The resulting laminated web, the pair of embossing rolls / flat roll temperature 225 ° C. / 215 ° C., and pressed pressure 300N / cm partial thermal, basis weight 55 g / ^{m 2,} bulk density 0.25 g / cm ^3, partial thermocompression bonding area A non-woven fabric face material having a rate of 25% was obtained.
A web was formed by a known card method using 60% of short polyester fibers (fiber diameter 17 μm, fiber length 51 mm) and 40% of copolymerized polyester short fibers (melting point 135 ° C., fiber diameter 20 μm, fiber length 38 mm). The non-woven fabric was entangled by needle punching to obtain a short fiber NP-processed non-woven fabric having a grain size of 1000 g / m ² , a bulk density of 0.04 g / cm ^{3, and a thickness of 25 mm.} A polyamide hot melt adhesive (melting point 130 ° C.) is ^{applied to the non-woven fabric face material at a ratio of 20 g / m 2} , and then heated to a temperature of 160 ° C. from the non-woven fabric face material side with a hot plate press using a 20 mm spacer. The non-woven fabric facing material and the obtained short fiber NP-processed non-woven fabric were adhered to obtain a composite sound absorbing material having a ^{grain size of 1075 g / m 2} , a bulk density of 0.538 g / cm ^{3, and a thickness of 20 mm.} Table 1 below shows various physical characteristics of the obtained composite sound absorbing material. In the composite sound absorbing material of Comparative Example 4, the basis weight or thickness of the short fiber NP-processed non-woven fabric as the base material was increased as compared with Comparative Examples 2 and 3, so that the sound absorbing property of low frequencies around 1000 Hz was improved. However, the sound absorption coefficient was low at frequencies of 2500 Hz and above.

[Comparative Example 5]
Polyethylene terephthalate (1% using orthochlorophenol, solution viscosity ηsp / c 0.77 by 25 ° C method, melting point 263 ° C) is spun from the spinneret, and the fiber web (S1) is spun at a spinning temperature of 300 ° C by the spunbond method. Formed on the collection net. On the obtained continuous long fiber web (mesh 40 g / m ² , average fiber diameter 12 μm), polyethylene terephthalate (also solution viscosity ηsp / c 0.50, melting point 260 ° C) was spun with a melt blow nozzle at a spinning temperature of 300 ° C and heated air 320. Direct ejection under the conditions of ° C. 1000 Nm ³ / hr formed ultrafine fiber webs (M) (meshing 20 g / m ² , average fiber diameter 2 μm). Next, using a two-component spinneret, a yarn having a sheath component of a copolymerized polyester resin (melting point 160 ° C.) and a core component of polyethylene terephthalate (melting point 263 ° C.) is spun into a continuous long fiber web (S2). (Grasping point 40 g / m ² , average fiber diameter 16 μm) was formed. The resulting laminated web, the pair of embossing rolls / flat roll temperature 230/145 ° C., partially thermocompression bonding at a linear pressure of 30 N / mm, basis weight 100 g / m ^2, bulk density 0.25 g / cm ^3, partial thermocompression bonding area ratio A 20% non-woven fabric facing material was obtained.
A web is formed by a known card method using 70% of short polyester fibers (fiber diameter 25 μm, fiber length 51 mm) and 30% of copolymerized polyester fibers (melting point 135 ° C., fiber diameter 15 μm, fiber length 51 mm), and needle punching. By entanglement by processing, a short fiber NP-processed non-woven fabric having a grain size of 375 g / m ² and a bulk density of 0.013 g / cm ^{3 and a thickness of 30 mm was obtained.} It was sandwiched between mesh conveyor belts and joined by heat treatment under heating and pressure in an atmosphere of 150 ° C. to obtain a composite sound absorbing material with a ^{grain size of 475 g / m 2} , a bulk density of 0.158 g / cm ^{3, and a thickness of 30 mm.} .. Table 1 below shows various physical characteristics of the obtained composite sound absorbing material. Although the composite sound absorbing material of Comparative Example 5 exhibited a wide sound absorbing performance, the weight as the sound absorbing material was heavy (the basis weight was high).

The composite sound absorbing material according to the present invention is thin, lightweight, and excellent in morphological stability in the low to medium frequency range of 1000 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz, while having high sound absorbing properties. Therefore, it can be suitably used as a sound absorbing material for automobile parts, building materials, home appliances, construction machinery, and the like.

Claims (4)

A composite sound absorbing material obtained by joining a non-woven fabric surface material containing at least one melt-blown ultrafine fiber layer having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ^{2 and an open cell resin foam layer.} The thickness of the composite sound absorbing material is 5 to 50 mm, the texture ^{is less than 50 to 475 g / m 2} , and the frequency of the sound incident from the non-woven fabric surface material side is 1000 Hz in the vertical incident measurement method conforming to JIS-1405. The composite sound absorbing material is characterized in that the sound absorbing coefficient of the composite sound absorbing material at 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, and 4000 Hz is 40% or more. In the non-woven fabric facing material, a melt-blown ultrafine fiber layer (M) having an average fiber diameter of 0.3 to 7 μm and a grain size of 1 to 40 g / m ² and a continuous long fiber layer (S) having an average fiber diameter of 10 to 30 μm are thermally pressure-bonded. The first aspect of claim 1, wherein the laminated non-woven fabric has an integrated SM type or SMS type laminated structure, the texture of the laminated nonwoven fabric is 20 to 250 g / m ² , and the air permeability is 100 cc / cm ^{2 / sec or less.} Composite sound absorbing material. When there are two or more non-woven fabric layers constituting the non-woven fabric face material, the layer of the non-woven fabric face material in contact with the open cell resin foam layer is 30 ° C. higher than the melting point of the fibers constituting the other layer of the non-woven fabric face material. The composite sound absorbing material according to claim 1 or 2, which comprises a fiber having a lower melting point. The composite sound absorbing material according to any one of claims 1 to ³ , wherein the open cell resin foam layer has a thickness of less than 5 to 50 mm and a bulk density of 0.01 to 0.1 g / cm 3.