JP4540417B2 - Sound absorbing material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sound-absorbing material excellent in sound absorption at a medium frequency, thin, lightweight, and excellent in form stability and suitable for automobile interiors and the like and a method for producing the same.

Conventionally, glass wool, rock wool, aluminum fibers, porous ceramics, scrap cotton, and the like have been used as sound absorbing materials in the interior of automobiles and houses. However, since these sound absorbing materials have problems in terms of workability, obstacles to the human body, recycling, environment, and the like, in recent years, various sound absorbing materials using nonwoven fabrics have been proposed.
For example, Patent Document 1 proposes a soundproof sheet material using a melt blown ultrafine fiber nonwoven fabric having a density of 0.013 to 0.05 g / 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, but thickness deformation tends to occur at a density of 0.01 to 0.1 g / cm ³ , and there is a problem in handling properties.
Patent Document 3, the fiber diameter contained the following ultrafine fibers 6 [mu] m, fluid and having a basis weight of 30 to 200 g / m ² nonwoven fabric having a fiber diameter of the short fiber nonwoven fabric having a basis weight of 50 to 2000 g / m ² in 7~40μm A sound absorbing material integrated by a confounding method or a needle punch method has been proposed. However, when the integration process is carried out by such a method, there is a drawback 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 300 g / m ² , and an apparent density of 0.01 to 0.10 g / cm ^3. A sound absorbing material comprising a fiber assembly having a basis weight of 50 to 2000 g / m ² has been proposed. However, this sound-absorbing material has low strength on the surface of the meltblown nonwoven fabric, and has problems in form stability, handling properties, and the like.
Further, Patent Document 5 includes a melt blown nonwoven fabric containing ultrafine fibers having a fiber diameter of 6 μm or less, a basis weight of 20 to 100 g / m ² , a fiber diameter of 7 to 40 μm, a basis weight of 50 to 2000 g / m ² , and a thickness of 5 to 30 mm. A sound absorbing material in which a short fiber nonwoven fabric is laminated and integrated has been proposed. However, even this sound-absorbing material has low strength on the surface of the meltblown nonwoven fabric, and has problems in form stability, handleability, and price.
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

  The object of the present invention is to solve the above-mentioned problems of the prior art, to obtain a sound absorbing material having a high sound absorbing property at a medium frequency range, thin, lightweight, excellent in form stability, and suitable for automobile interior use and the like. To provide a law.

As a result of diligent research in view of the above problems, the inventors of the present invention have made the surface material small by joining the surface material having a dense structure that has been thermocompression bonded and the back material having a rough structure with a hot melt adhesive or the like. The sound that penetrated into the air gap was transmitted to the single fiber yarn on the back material and vibrated to efficiently convert it into thermal energy, so it was found that the sound energy was reduced and the sound absorption was greatly improved. The invention has been reached.
That is, the invention claimed in the present application is as follows.

(1) A bonded non-woven fabric of a surface material composed of a thermoplastic synthetic long- fiber non-woven fabric and a back surface composed of a synthetic non-woven fabric by a spunbond method, which is further calendered after partial thermocompression bonding, and the average of the fibers of the surface material The fiber diameter is 10 to 30 μm, the thickness is 0.03 to 1 mm, the average apparent density is 0.3 g / cm ³ or more, the basis weight is 20 to 250 g / m ² , and the thickness of the back material is 5 to 45 mm and the average appearance A sound-absorbing material having a density of 0.1 g / cm ³ or less, a thickness of the bonded nonwoven fabric of 5 to 50 mm, a basis weight of 100 to 1000 g / m ^2, and a sound absorption rate of 4000 Hz or more. .
(2) The sound absorbing material according to (1), wherein an average fiber diameter of fibers constituting the surface material and the back surface material is 10 to 30 μm.
(3) The sound-absorbing material according to (1) or (2), wherein the surface material and the back material are composed of fibers mainly composed of a polyester fiber or a polyester copolymer fiber.
(4) The sound absorbing material according to any one of (1) to (3), wherein the constituent fibers of the surface material are irregular cross-section fibers.
(5) The sound absorbing material according to any one of (1) to (4), wherein the constituent fiber of the surface material is a composite fiber.
(6) The sound absorbing material according to any one of (1) to (5), wherein the surface material is a long-fiber non-woven fabric and is thermocompression bonded at a partial thermocompression rate of 3 to 35%.
(7) Any one of (1) to (6), wherein the back material is a short fiber nonwoven fabric and contains 5 to 50% by weight of heat-fusible fiber and / or flame-retardant fiber. The sound absorbing material according to crab.
(8) The sound absorbing material according to any one of (1) to (7), wherein 5 to 50% by weight of a synthetic resin is applied to the nonwoven fabric constituting the back material.

(9) Heat by a partial thermocompression-bonded spunbond method having a thickness of 0.03 to 1 mm, an average apparent density of 0.3 g / cm ³ or more, a basis weight of 20 to 250 g / m ² and an average fiber diameter of 10 to 30 μm When producing a sound-absorbing material by joining a surface material made of a plastic synthetic long- fiber nonwoven fabric and a back material made of a synthetic fiber nonwoven fabric having a thickness of 5 to 45 mm and an average apparent density of 0.1 g / cm ³ or less, the surface material A method for producing a sound-absorbing material, characterized in that heat treatment is performed with an adhesive or a heat-sealing fiber interposed between the back surface material and the back surface material.

The sound-absorbing material of the present invention is made of a thermoplastic synthetic fiber nonwoven fabric having a high density structure with small voids on the surface material. Therefore, the sound absorbing material has a rough structure having a small sound wavelength and entering into the voids of the nonwoven fabric and having large voids. The invading sound wave is transmitted to and vibrated into the single fiber yarn of the back material made of synthetic fiber nonwoven fabric, so that sound energy can be efficiently converted into thermal energy, and an excellent sound absorption effect can be obtained. In addition, by joining the surface material and the back material by using a hot melt adhesive or the like, it is possible to obtain a bonded nonwoven fabric having a specific thickness, basis weight, etc., so there is no formation of through holes and an excellent sound absorbing effect. getting can, or friction strength, excellent in piercing strength, has excellent dimensional stability, excellent in such cutting processability, good handling properties are obtained.

The present invention will be described in detail below.
The sound-absorbing material of the present invention is composed of a bonded non-woven fabric of a surface material made of a thermoplastic synthetic fiber non-woven fabric and a back material made of a synthetic fiber non-woven fabric.
The surface material used in the present invention has a thickness of 0.03 to 1 mm, preferably 0.04 to 0.7 mm, and an average apparent density of 0.3 g / cm ³ or more, preferably 0.35 to 1.0 g. / M ² and a basis weight of 20 to 250 g / m ² , preferably 30 to 200 g / m ² . By adopting such a configuration, the surface material has a high-density structure, and the wavelength of sound that enters can be reduced by the frictional resistance in the pores. When the thickness of the surface material is less than 0.03 mm, the average apparent density is less than 0.3 g / cm ³ , and the basis weight is less than 20 g / m ² , the strength, rigidity, handleability, fiber density, etc. are lowered, and the sound absorption effect is lowered. To do. On the other hand, when the thickness exceeds 1 mm and the basis weight exceeds 250 g / m ² , the strength and the fiber density increase, but the rigidity is too high and the cutting property and the handling property deteriorate.

The thermoplastic synthetic fiber nonwoven fabric constituting the surface material is preferably a partially thermocompressed long fiber nonwoven fabric obtained by a known spunbond method or the like, and the partial thermocompression bonding rate is preferably in the range of 3 to 35%, more Preferably it is 5 to 30%. The partial thermocompression bonding is preferably made uniform over the entire surface, but the shape of the partial thermocompression bonding is not particularly limited. If the partial thermocompression rate is less than 3%, sufficient strength of the nonwoven fabric cannot be obtained, and if it exceeds 35%, the non-partial crimping portion is reduced and the voids of the nonwoven fabric through which sound enters decreases. As a method of partial thermocompression bonding, it is basically carried out once with an uneven metal embossing roll / metal flat roll, but the entire surface is calendered with a combination of metal embossing / rubber, paper, cotton roll, etc. May be.
Or after partial thermocompression bonding, it is further divided into two stages by a pair of metal flat roll / metal flat roll, metal flat roll / paper roll, metal flat roll / cotton roll, metal flat roll / resin roll, and the entire surface is calendered Is preferable from the viewpoint of densification of the surface material. The thermocompression bonding or calendering is preferably performed at a temperature lower by about 15 to 80 ° C. than the resin melting point of the thermoplastic synthetic fiber at a linear pressure of 100 to 1000 N / cm.

Back sheet used in the present invention has a thickness 5～45Mm, preferably 7～40Mm, average apparent density of 0.1 g / cm ³ or less, preferably 0.01~0.07g / cm ^3. By adopting such a configuration, a rough structure can be obtained, and a sound wave having a reduced wavelength invading from a surface material having a dense structure can be efficiently transmitted to the fiber single yarn to vibrate the fiber single yarn. Can do. When sound energy is converted into thermal energy by vibration of a single yarn, a sound absorbing effect is exhibited. If the thickness of the back material is less than 5 mm, the sound absorbing effect is reduced because the thickness is too thin. On the other hand, when the average apparent density exceeds 0.1 g / cm ³ , a dense structure is obtained, and the vibration of the fiber single yarn is lowered, so that the sound absorbing effect is lowered. As described above, the back material has a role of effectively vibrating the constituent fiber single yarn of the synthetic fiber nonwoven fabric having a rough structure to reduce sound energy and greatly improve sound absorption.

  The nonwoven fabric made of the synthetic fiber of the back material can be obtained by laminating short fibers or short fibers and long fibers, and entangled by a known needle punch method or the like. Further, in order to bond the entangled fibers, a synthetic resin may be applied to the nonwoven fabric by a heat treatment, a spray method, a dipping method, a kiss roll method, or the like. By combining the entangled fibers, vibration energy can be efficiently converted into thermal energy, and the change in the thickness of the nonwoven fabric can be reduced, thereby improving the handleability. Examples of the synthetic resin to be applied include water-based emulsions such as known acrylic resins, synthetic rubber resins, vinyl acetate resins, urethane resins, ester resins, and the like. More preferably, it is 7 to 30%.

In addition, functions such as adhesion of constituent fibers, rigidity and flame retardancy can be added to the nonwoven fabric used for the back material. For example, a heat-fusible fiber, a flame-retardant fiber, or the like may be contained in the range of 5 to 50% by weight with respect to the fiber weight. More preferably, it is 10 to 30% by weight.
Examples of the heat-fusible fiber include a composite fiber having a sheath part made of polyethylene, polypropylene, copolymerized ester, etc. and a core part made of polypropylene, polyethylene terephthalate, or the like, and a low-melting copolymer polyester fiber. Examples of the flame retardant fiber include fibers kneaded into a resin such as a phosphorus resin, a thiourea resin, and a halogen resin. Further, a flame retardant resin may be mixed with the aqueous emulsion.

  In the present invention, the surface material and the back material include, for example, polyolefin fibers such as polyethylene, polypropylene, copolymer polypropylene, polyamide fibers such as nylon 6, nylon 66, copolymer polyamide, polyethylene terephthalate, polybutylene terephthalate, co-polymer. Polyester-based fibers such as polymerized polyester and aliphatic polyester, composite fibers such as a core-sheath structure in which the sheath is composed of polyethylene, polypropylene or copolymer polyester and the core is composed of polypropylene or polyester, polylactic acid, polybutylene succinate, polyethylene succin Thermoplastic synthetic fibers such as biodegradable fibers such as nates can be used. In addition to these, synthetic fibers such as polyurethane fibers can be used as the back material. These fibers can be used alone or in admixture of two or more, and can also be used by mixing or laminating irregular cross-section fibers such as flat yarns, crimped fibers, split fibers and the like. In particular, polyester fibers are preferred from the viewpoint of heat resistance and flame retardancy.

  Moreover, the average fiber diameter of the fibers constituting the surface material and the back material is preferably in the range of 10 to 30 μm, more preferably 12 to 25 μm. In particular, the fiber diameter of the surface material is preferably reduced in order to obtain a high-density structure having small voids. In order to form smaller fiber voids in thermocompression bonding, it is more preferable to use thick fibers mixed with thin fibers, irregular cross-section fibers, composite fibers, amorphous fibers, and the like.

The sound-absorbing material of the present invention is obtained by joining the above-described surface material having a dense structure and the back material having a rough structure. Examples of the bonding method include a method of performing heat treatment by interposing an adhesive fiber or an adhesive on the bonding surface of the front surface material or the back surface material. Specifically, after applying about 5 to 30 g / m ^{2 of} heat-fusible fiber, hot-melt powder resin, and adhesive, heat treatment, or applying hot-melt resin by curtain spray method and then joining. A method is mentioned. In particular, it is preferable to laminate or mix the heat-sealing fibers on the back surface material and heat-treat at the time of joining with the surface material to melt the heat-sealing fibers and join them.

Sound-absorbing material of the present invention has a thickness of 5 to 50 mm, preferably 8 to 40 mm, more preferably 10 to 30 mm, a basis weight of 100 to 1000 g / m ^2, preferably 120~800g / m ^2, more preferably 140 a ~600g / m ^2, also the sound absorption coefficient of frequency 4000Hz is 50% or more, preferably 60% or more, more preferably 70% or more.
The sound absorption coefficient in the medium frequency range (2000 to 4000 Hz) can be improved by increasing the thickness of the sound absorbing material and increasing the apparent density of the surface material. Although this causes a problem, in the present invention, by setting the thickness and basis weight of the sound absorbing material within the above range, the sound absorption rate at a frequency of 4000 Hz is ensured to be 50% or more, and the winding workability, the cutting workability, the overpacking and the transportation are ensured. A sound-absorbing material excellent in handling properties such as time can be obtained. In addition, the sound absorbing material of the present invention has little edge sag during handling and the thickness of the entire thickness, and can provide stable sound absorbing properties after construction.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. The characteristics in the examples were measured by the following methods.
1) Weight per unit area (g / m ² ): According to JIS-1913.
2) Average fiber diameter (μm): Take a 500 times magnified photograph with a microscope, and obtain the average value of 10 fibers.
3) Average apparent density (g / cm ³ ): Calculated from (weight per unit area) / (thickness) to determine the weight per unit volume.
4) Thickness (mm): According to JIS-L-1913-B method. Three or more thicknesses of pressure with a load of 0.02 kPa are measured, and the average value is shown. However, the thickness of the surface material was measured at a load of 20 kPa.
5) Sound absorption (%): Frequency 2000 to 4000 Hz is measured with a measuring device using a vertical incidence method according to JIS-1405.
6) Breathability (cc / cm ² / sec): Measured by JIS-L-1906 Frajour type method.

[Example 1-9, Comparative Examples 1-3]
Using a known spunbond method, polyethylene terephthalate (1% using o-chlorophenol, melt viscosity ηsp / c 0.77 of the 25 ° C. method) was spun from a spinneret at a temperature of 300 ° C. by a melt spinning method, The fiber diameters and basis weight long fiber webs shown in Table 1 were obtained by drawing, opening, and collecting processes using a high-speed traction device. The long fiber web is partially thermocompression bonded with a pair of embossing rolls / flat rolls at a temperature of 230 ° C. and a linear pressure of 500 N / cm, and further with a pair of metal flat rolls / metal flat rolls at a temperature of 235 ° C. and a linear pressure of 1000 N / cm. Were subjected to calendering (Examples 1 to 7) shown in Table 1 to obtain an apparent density nonwoven fabric for surface material.

In addition, the nonwoven fabric for surface material of Example 8 was obtained by a known spunbond method using a polyethylene terephthalate resin (melting point: 256 ° C., intrinsic viscosity: 0.71) at an extruder temperature of 300 ° C. and a flatness ratio of 2.5 (fiber cross section). A filament is spun using a flat-shaped atypical cross-section spinneret with a short axis length A and a long axis length B ratio B / A), and is drawn with an air soccer ball at a high-speed airflow traction device (spinning speed 4500 m / s). min), cooling, fiber opening, and collecting steps, a long fiber web having a fiber diameter of 18 μm and a basis weight of 70 g / m ² shown in Table 1 was obtained. The long fiber web is partially thermocompression bonded at a pair of embossing roll / flat roll temperature of 220 ° C. and a linear pressure of 300 N / cm, and further at a temperature of 230 ° C. and a linear pressure of 500 N / cm with a pair of metal flat roll / metal flat roll. The nonwoven fabric for surface materials having an apparent density shown in Table 1 was obtained by calendering (Example 8).

Further, the nonwoven fabric for surface material of Example 9 is a known spunbond method, which is a two-component spinning method in which the core is a polyethylene terephthalate resin (melting point 256 ° C., intrinsic viscosity 0.71) and the sheath is a polyethylene resin (melting point 130 ° C.). By melt spinning, a long fiber web having a fiber diameter of 15 μm and a basis weight of 100 g / m ² was obtained. The long fiber web is partially thermocompression bonded at a pair of embossing roll / flat roll temperature of 110 ° C. and a linear pressure of 300 N / cm, and further at a temperature of 115 ° C. and a linear pressure of 500 N / cm with a pair of metal flat roll / metal flat roll. The nonwoven fabric for surface material with an apparent density shown in Table 1 was obtained by calendering (Example 9).

As the nonwoven fabric for the back material, in Examples 1 to 3 and 8 to 9 , a polyester short fiber card web having a fiber diameter of 25, a fiber length of 51 mm, and a basis weight of 180 g / m ² is needle punched, and further an aromatic phosphate ester The nonwoven fabric for back materials shown in Table 1 was used, in which a water-soluble acrylic resin containing 30% of a water-based flame retardant was attached by spraying at a rate of 20 g / m ² .
In Examples 4 to 7, a card web of 70% polyester short fibers having a fiber diameter of 25 μm and a fiber length of 51 mm, and 30% copolymer polyester short fibers having a fiber diameter of 18 μm, a fiber length of 51 mm, and a melting point of 135 ° C. is needle punched. Furthermore, the nonwoven fabric for back materials shown in Table 1 in which a water-soluble acrylic resin containing 30% of an aromatic phosphate ester water-dispersed flame retardant was attached by spraying at 20 g / m ² was used.
Next, the surface material and the back material were bonded using a hot melt adhesive to obtain the sound absorbing material of the present invention. Specifically, a hot melt powder of a copolyester resin (melting point 130 ° C.) is uniformly placed at 20 g / m ² on the surface material, and then heated and melted with a heat treatment machine, and then the surface material is overlaid. And glued.

In Comparative Example 1, only the thin surface material is used as the sound absorbing material, in Comparative Example 2, only the back material having a rough structure is used as the sound absorbing material, and in Comparative Example 3, the surface material is low in bulk density and has high air permeability. The back material was joined by the hot melt powder method in the same manner as in Example 1 to obtain a sound absorbing material.
The properties of the obtained sound absorbing material are shown in Table 1. It was found that the sound absorbing material of the present invention has excellent sound absorbing properties. Further, these sound absorbing materials had a low rate of change in thickness and excellent handleability. On the other hand, the sound absorbing materials of Comparative Examples 1 to 3 had a low sound absorbing property.

The sound-absorbing material of the present invention has a high sound-absorbing property at a medium peripheral wavelength, is thin and lightweight, and has excellent shape stability.

Claims (9)

After partial thermocompression bonding, a non-woven fabric bonded with a surface material made of a thermoplastic synthetic long- fiber non-woven fabric and a back material made of a synthetic fiber non-woven fabric by a calendered spunbond method, and the average fiber diameter of the fibers of the surface material is 10 to 30 μm, thickness is 0.03 to 1 mm, average apparent density is 0.3 g / cm ³ or more and basis weight is 20 to 250 g / m ² , the thickness of the back material is 5 to 45 mm and average apparent density is 0 .1g / cm ³ or less, sound absorbing material further thickness of the bonding nonwoven 5 to 50 mm, a basis weight of 100 to 1000 g / m ² and the frequency 4000Hz sound absorption coefficient is equal to or less than 50%.   The sound absorbing material according to claim 1, wherein an average fiber diameter of fibers constituting the surface material and the back material is 10 to 30 µm.   The sound absorbing material according to claim 1 or 2, wherein the front surface material and the back surface material are composed of fibers mainly composed of polyester fibers or polyester copolymer fibers.   The sound absorbing material according to any one of claims 1 to 3, wherein the constituent material of the surface material is a modified cross-section fiber.   The sound absorbing material according to any one of claims 1 to 4, wherein the constituent fiber of the surface material is a composite fiber.   The sound absorbing material according to any one of claims 1 to 5, wherein the surface material is a long-fiber non-woven fabric and is thermocompression bonded at a partial thermocompression bonding rate of 3 to 35%.   The sound absorbing material according to any one of claims 1 to 6, wherein the back material is a short fiber nonwoven fabric and contains 5 to 50% by weight of heat-fusible fiber and / or flame retardant fiber. Wood.   The sound absorbing material according to any one of claims 1 to 7, wherein 5 to 50% by weight of a synthetic resin is applied to the nonwoven fabric constituting the back material. Thickness 0.03～1Mm, average apparent density of 0.3 g / cm ³ or more, thermoplastic synthetic long by partial thermal crimped spunbond an average fiber diameter of 10~30μm having a basis weight of 20 to 250 g / m ² and fibers When manufacturing a sound-absorbing material by joining a surface material made of a fiber nonwoven fabric and a back material made of a synthetic fiber nonwoven fabric having a thickness of 5 to 45 mm and an average apparent density of 0.1 g / cm ³ or less, the surface material and the back material A method for producing a sound-absorbing material, characterized in that a heat treatment is performed with an adhesive or a heat-sealing fiber interposed therebetween.