JP2009186825A - Sound absorbing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing structure which has wide and excellent sound absorption characteristics from low frequency to high frequency without impairing a lightweight performance and a shape stabilization. <P>SOLUTION: The sound absorbing structure is characterized in that nonwoven fabrics of the thickness of <5 mm in thickness are laminated in a fiber structure of 5 to 50 mm in thickness, the nonwoven fabrics are arranged at a sound source side, and gas permeability of the nonwoven fabric is within 15 to 100 cc/cm<SP>3</SP>/sec. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure that can be suitably used for noise reduction in vehicles, houses, roads, and the like. More particularly, the present invention relates to a sound absorbing structure having a wide and good sound absorbing characteristic from low frequency to high frequency without impairing lightness and form stability.

  Conventionally, glass wool, urethane foam, polyester fiber, and high-melting thermoplastic fiber and low-melting thermoplastic fiber are used as sound absorbing and sound insulating materials for vehicles, houses, and highways (see, for example, Patent Document 1). Many sound-absorbing materials using various fibers have been proposed.

The properties required for such a sound absorbing material include sound absorbing properties, light weight, and form stability. In particular, in terms of sound absorption, wide and good sound absorption characteristics are required from low frequencies to high frequencies.
As a method for improving the sound absorption of such a sound absorbing material, methods such as reducing the fiber diameter or increasing the basis weight have been conventionally used.

However, if the fiber diameter is simply reduced, a wide and good sound absorption characteristic from low frequency to high frequency cannot be obtained sufficiently, and the form stability is also impaired. On the other hand, there is a problem in that lightness is impaired simply by increasing the basis weight.
For this reason, a method for improving sound absorption by constructing a sound absorbing material with a fiber structure wrapped with a highly ventilated skin material (see, for example, Patent Document 2) or a nonwoven fabric containing ultrafine fibers (for example, Patent Document) 3) is proposed.

Although these methods can achieve sound absorption in the medium and high frequency region of 800 Hz or higher without impairing lightness and form stability, it is still not sufficient in terms of sound absorption in the low frequency region, and the improvement is It was desired.
On the other hand, Patent Document 4 proposes a sound-absorbing structure in which a nonwoven fabric having a low air permeability is laminated on a fiber structure and the nonwoven fabric is arranged on the sound source side. However, it has been found that the sound absorbing structure still has room for improvement in terms of sound absorption characteristics.

JP-A-7-3599 JP 2000-305574 A JP 2002-161464 A JP 2004-145180 A

  The present invention has been made in view of the above background, and an object of the present invention is to provide a sound-absorbing structure that has wide and good sound-absorbing characteristics from low frequencies to high frequencies without impairing lightness and form stability. .

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have laminated a non-woven fabric on a fiber structure and arranged the non-woven fabric on the sound source side to obtain a sound-absorbing structure. It was found that when the manufactured nonwoven fabric or the wet spunlace nonwoven fabric was used and the air permeability of the nonwoven fabric was increased to some extent, better sound absorption characteristics were obtained from low frequencies to high frequencies, and the present invention was further intensively studied. It came to be completed.

Thus, according to the present invention, “a non-woven fabric having a thickness of less than 5 mm is laminated on a fiber structure having a thickness of 5 to 50 mm, and the non-woven fabric is disposed on the sound source side. The nonwoven fabric is a nonwoven fabric produced by a wet papermaking method or a wet spunlace nonwoven fabric, and the air permeability of the nonwoven fabric is in the range of 15 to 100 cc / cm ³ / sec. Body. "

In that case, it is preferable that the single fiber fineness of the fiber which comprises the said nonwoven fabric exists in the range of 0.01-2 dtex. Moreover, it is preferable that the fabric weight of the said nonwoven fabric exists in the range of 5-80 g / m < ² >. The non-woven fabric is a non-woven fabric produced by a wet papermaking method, and the non-woven fabric is composed of a polyester fiber and a binder fiber, and the weight ratio of the polyester fiber and the binder fiber is (the former: the latter) 80:20. It is preferable to be within the range of ˜20: 80. The nonwoven fabric is a wet spunlace nonwoven fabric, the nonwoven fabric is composed of polyester fibers and / or binder fibers, and the weight ratio of the polyester fibers to the binder fibers (the former: the latter) 100: 0 to 70: Preferably it is within the range of 30. In that case, it is preferable that the binder fiber is an unstretched fiber or a heat-adhesive conjugate fiber composed of a heat-fusion component and a fiber-forming thermoplastic polymer, at least the heat-fusion component being exposed on the fiber surface .

In the sound absorbing structure of the present invention, it is preferable that the single fiber fineness of the fibers constituting the fiber structure is in the range of 0.9 to 20 dtex. Moreover, it is preferable that the density of the said fiber structure exists in the range of 0.005-0.10 g / cm < ³ >. Moreover, the said fiber structure is comprised from a polyester-type fiber and a binder fiber, and the weight ratio of a polyester-type fiber and a binder fiber exists in the range of 90: 10-50: 50 (the former: latter). preferable.
In the sound absorbing structure of the present invention, it is preferable that the weight ratio of the nonwoven fabric to the fiber structure is in the range of (the former: the latter) 20:80 to 1:99.

  ADVANTAGE OF THE INVENTION According to this invention, the sound-absorbing structure which has a wide and favorable sound absorption characteristic from a low frequency to a high frequency is obtained, without impairing lightweight property and form stability.

Hereinafter, embodiments of the present invention will be described in detail.
The sound absorbing structure of the present invention has a two-layer structure in which a nonwoven fabric and a fiber structure are laminated.
First, it is important that the nonwoven fabric has a thickness of less than 5 mm (preferably 0.01 to 3 mm). When the thickness is 5 mm or more, not only the weight of the sound absorbing structure is increased, but the air permeability is too low, and the air permeability in the following range may not be obtained.

Moreover, in such a nonwoven fabric, it is important that the air permeability is in the range of 15 to 100 cc / cm ³ / sec (preferably 30 to 80 cc / cm ³ / sec). If the air permeability of the nonwoven fabric is larger than 100 cc / cm ³ / sec, the surface resistance against sound energy is too small and does not contribute to energy attenuation, which is not preferable. On the other hand, if the air permeability of the nonwoven fabric is less than 15 cc / cm ³ / sec, the nonwoven fabric vibrates due to sound waves, and the sound waves do not propagate to the fiber structure located behind and are undesirably reflected on the surface of the nonwoven fabric. . The air permeability is measured according to JIS L1096 6.27.1 (Fragile method).

  The nonwoven fabric preferably has a single fiber fineness within a range of 0.01 to 2 dtex (more preferably 0.05 to 0.3 dtex). If the single fiber fineness is larger than 2 dtex, there is a possibility that the sound absorbing property of the sound absorbing material, particularly sufficient sound absorbing property in the low frequency region cannot be obtained. On the other hand, if the single fiber fineness is less than 0.01 dtex, not only is it difficult to produce the fiber, but there is a risk that the handleability may be reduced, which is not preferable. As the fineness, if there are many types of fibers constituting the nonwoven fabric, a value obtained by weighted averaging the single yarn fineness is used.

Further, the basis weight of the nonwoven fabric is 5 to 80 g / m ² (in the case where the nonwoven fabric is a nonwoven fabric produced by a wet papermaking method, it is particularly preferably within the range of 10 to ²⁰ g / m ² , and the nonwoven fabric is a wet spunlace. In the case of a nonwoven fabric, it is particularly preferably within the range of 30 to 50 g / m ² . If the basis weight is less than 5 g / m ² , the air permeability becomes too high, and the air permeability in the above range may not be obtained, so that sufficient sound absorption may not be obtained. On the contrary, if the basis weight is larger than 80 g / m ² , not only does the weight of the sound absorbing structure increase, but also the air permeability becomes too low, and the air permeability in the above range cannot be obtained and sufficient sound absorbing properties cannot be obtained. There is a fear.

  It is important that the nonwoven fabric is (1) a nonwoven fabric produced by a wet papermaking method, or (2) a wet spunlace nonwoven fabric. At that time, (1) the nonwoven fabric is a nonwoven fabric produced by a wet papermaking method, the nonwoven fabric is composed of polyester fibers and binder fibers, and the weight ratio of the polyester fibers and binder fibers is (the former: the latter) The nonwoven fabric in the range of 80:20 to 20:80, or (2) the nonwoven fabric is a wet spunlace nonwoven fabric (a nonwoven fabric in which fibers are entangled with each other by a high-pressure water flow after obtaining a sheet by a wet papermaking method), The nonwoven fabric is preferably a nonwoven fabric composed of polyester fibers and / or binder fibers, and the weight ratio of the polyester fibers to the binder fibers (the former: the latter) being in the range of 100: 0 to 70:30. . In particular, a wet spunlace nonwoven fabric is preferable because of its excellent moldability. Non-woven fabrics (spunbond, meltblown, etc.) from direct spinning, dry raid methods such as card, airlaid, etc., because the average fiber diameter is thin, the texture is good (small spots), and stable production is difficult. The nonwoven fabric that can be used in the present invention cannot be obtained, which is not preferable.

  Here, in the nonwoven fabric produced by the (1) wet papermaking method, the weight ratio of the polyester fiber that is the main fiber is larger than 80 wt% (the weight ratio of the binder fiber is smaller than 20 wt%), Since there are too few adhesion points for maintaining the structure of the nonwoven fabric, the nonwoven fabric may be destroyed even with a slight impact. On the contrary, if the weight ratio of the polyester fiber as the main fiber is smaller than 20% by weight (the weight ratio of the binder fiber is larger than 80% by weight), the nonwoven fabric is strong, but shrinks during the production of the nonwoven fabric. In addition, there is a risk of spots and adhesion to the dryer. (2) In wet spunlace nonwoven fabric, if the weight ratio of polyester fiber as the main fiber is smaller than 70% by weight (weight ratio of binder fiber is larger than 30% by weight), the nonwoven fabric is strong However, it shrinks during the production of the nonwoven fabric, and there is a possibility that spots and adhesion to the dryer may occur.

Examples of the polyester fiber include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyhexamethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, fiber made of polypivalolactone or a copolymer thereof, or the above Examples thereof include composite fibers composed of two or more types selected from the group of polymer components, polylactic acid fibers, stereocomplex polylactic acid fibers, and chemically or material recycled polyester fibers. Of these, polyethylene terephthalate fiber, polybutylene terephthalate fiber, and composite fiber containing polyethylene terephthalate as one component are particularly preferred from the viewpoint of fiber formation.
In addition, various stabilizers, ultraviolet absorbers, thickening and branching agents, matting agents, colorants, other various improving agents, and the like may be blended in the polymer constituting the fibers as necessary.

And as a form of these fibers, a long fiber may be sufficient and a short fiber may be sufficient. Furthermore, the short fiber to which crimp was provided may be sufficient. In this case, the crimping method is as follows: 1) Using a composite fiber in which polymers having different heat shrinkage rates are bonded to the side-by-side type, the crimp is applied in a spiral shape. 2) The spiral crimp is applied by anisotropic cooling. 3) Various methods such as providing a zigzag crimp by the indentation crimp method can be used.
Moreover, the single fiber cross-sectional shape of a fiber can use well-known things, such as a circle, a triangle, and a flat shape.

Here, the polyester fiber used as the main fiber is preferably crimped in terms of sound absorption, and in particular, crimped in a spiral shape by anisotropic cooling in terms of bulkiness and manufacturing cost. Those provided with are preferred.
On the other hand, the binder fiber is an unstretched fiber (for example, unstretched polyester fiber), or a thermal adhesive property in which at least the heat-sealable component is exposed on the fiber surface. Bicomponent fibers are preferred.

  As such a heat-adhesive conjugate fiber, a fiber composed of a heat-fusible component and a fiber-forming thermoplastic polymer, at least the former being exposed on the fiber surface, can be used. As a weight ratio, the range of 30/70 to 70/30 is appropriate for the former and the latter. The composite form of the heat-adhesive conjugate fiber may be a side-by-side type or a core-sheath type, but the latter is preferred. In this core-sheath type, the fiber-forming thermoplastic polymer becomes the core, but the core may be concentric or eccentric. In particular, an eccentric shape is preferable because spiral crimps appear. The cross-sectional shape of the composite fiber may be hollow, solid, or atypical.

The heat-fusible component of the heat-adhesive conjugate fiber preferably has a melting point that is lower by 40 ° C. or more than the polymer component constituting the polyester short fiber. If this temperature difference is less than 40 ° C., the adhesion is insufficient, and there is a risk that a sound absorbing structure which does not have a waist and is difficult to handle can be obtained.
Here, examples of the polymer arranged as the heat fusion component include polyurethane elastomers, polyester elastomers, inelastic polyester polymers and copolymers thereof, polyolefin polymers and copolymers thereof, polyvinyl alcohol polymers, and the like. be able to.

  Examples of the polyurethane elastomer include low melting point polyols having a molecular weight of about 500 to 6000, such as dihydroxy polyether, dihydroxy polyester, dihydroxy polycarbonate, dihydroxy polyester amide and the like, and organic diisocyanates having a molecular weight of 500 or less, such as p, p′-diphenyl. Methane diisocyanate, tolylene diisocyanate, isophorone diisocyanate hydrogenated diphenyl methane isocyanate, xylylene isocyanate, 2,6-diisocyanate methylcaproate, hexamethylene diisocyanate and the like, and chain extenders having a molecular weight of 500 or less, such as glycol amino alcohol or triol It is a polymer obtained by reaction with.

  Among these polymers, particularly preferred is a polyurethane using polytetramethylene glycol, poly-ε-caprolactam or polybutylene adipate as a polyol. Examples of the organic diisocyanate in this case include p, p'-bishydroxyethoxybenzene and 1,4-butanediol.

  In addition, as a polyester-based elastomer, a polyetherester copolymer obtained by copolymerizing thermoplastic polyester as a hard segment and poly (alkylene oxide) glycol as a soft segment, more specifically, terephthalic acid, isophthalic acid, phthalic acid Alicyclic dicarboxylic acids such as naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, oxalic acid, At least one dicarboxylic acid selected from aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dodecanedioic acid, dimer acid, or ester-forming derivatives thereof, 1,4-butanediol, ethylene glycol trimethylene glycol, Tetramethylene glycol, Aliphatic diols such as tamethylene glycol, hexamethylene glycol neopentyl glycol, decamethylene glycol, or alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane methanol, or the like At least one diol component selected from ester-forming derivatives and the like, and polyethylene glycol, poly (1,2- and 1,3-polypropylene oxide) glycol, poly (tetramethylene oxide) having an average molecular weight of about 400 to 5000 ) Consists of at least one of poly (alkylene oxide) glycols such as glycol, a copolymer of ethylene oxide and propylene oxide, and a copolymer of ethylene oxide and tetrahydrofuran It can be mentioned terpolymer.

  In particular, from the viewpoint of adhesiveness, temperature characteristics, and strength, a block copolymer polyether ester having polybutylene terephthalate as a hard component and polyoxybutylene glycol as a soft segment is preferable.

  In this case, the polyester portion constituting the hard segment is polybutylene terephthalate in which the main acid component is terephthalic acid and the main diol component is a butylene glycol component. Of course, part of this acid component (usually 30 mol% or less) may be substituted with another dicarboxylic acid component or oxycarboxylic acid component, and part of the glycol component (usually 30 mol% or less) is also butylene. It may be substituted with a dioxy component other than the glycol component. Moreover, the polyether part which comprises a soft segment may be the polyether substituted by dioxy components other than butylene glycol.

Copolyester polymers include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and naphthalenedicarboxylic acid and / or fats such as hexahydroterephthalic acid and hexahydroisophthalic acid. A co-polymer containing a predetermined number of cyclic dicarboxylic acids and aliphatic or alicyclic diols such as diethylene glycol, polyethylene glycol, propylene glycol, and paraxylene glycol, with addition of oxyacids such as parahydroxybenzoic acid as desired. Polymerized esters and the like can be mentioned, and for example, polyester obtained by adding and copolymerizing isophthalic acid and 1,6-hexanediol to terephthalic acid and ethylene glycol is preferable.
Examples of the polyolefin polymer include low density polyethylene, high density polyethylene, and polypropylene.

Examples of the fiber-forming thermoplastic polymer that is the counterpart component of the above heat-fusion component include polyesters such as polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, and polyolefin polymers.
The binder fiber is also preferably a short fiber and has been crimped, like the polyester fiber that is a main fiber.

  Further, as a method for obtaining the specific weight and air permeability as described above, a resin may be attached to the fibers forming the nonwoven fabric. Such a method is particularly suitable for controlling the air permeability. Further, by attaching resin to the fibers, it becomes possible to suppress the fluff on the surface of the nonwoven fabric, and further, the effect of improving the rigidity of the nonwoven fabric and improving the shape stability of the sound absorbing structure can be obtained.

As such a resin, a known resin can be used, and examples thereof include acrylate resin, urethane resin, polyester resin, silicone resin, melamine resin, polypropylene resin, and fluororesin acrylic resin.
In this case, the amount of resin attached is suitably in the range of 5 to 50% by weight with respect to the fiber weight.

  In the sound absorbing structure of the present invention, the thickness of the fiber structure is preferably 5 to 50 mm (more preferably 8 to 20 mm). When the thickness is larger than 50 mm, it is difficult to integrate the nonwoven fabric and the fiber structure, and there is a possibility that the stability as a product, such as peeling, may be lacked during use. On the other hand, when the thickness is smaller than 5 mm, even if a nonwoven fabric is laminated, the sound absorbing property may be too low.

  Moreover, it is preferable that a fiber structure is comprised with the main fiber and binder fiber which consist of polyester type fibers similarly to the said nonwoven fabric. At that time, the ratio of the main fiber to the binder fiber is preferably 90/10 to 50/50 (more preferably 80/20 to 60/40). When the main fiber is larger than 90% (the binder fiber is smaller than 10%), the number of adhesion points of the fiber structure is too small, and the structure maintenance may become unstable. Conversely, if the main fiber is smaller than 50% (the binder fiber is larger than 50%), the fiber structure becomes too hard, and it is difficult to integrate with the nonwoven fabric, and even if it can be apparently, it is easy to peel off. Problems may arise.

  Moreover, it is preferable that the single fiber fineness of the fiber which comprises a fiber structure exists in the range of 0.9-20 dtex. If the single fiber fineness is larger than 20 dtex, the voids of the fiber structure may be greatly scrambled and satisfactory sound absorption, which is the main object of the present invention, may not be obtained. On the other hand, if the single fiber fineness is less than 0.9 dtex, not only will it be difficult to produce the fiber structure, but there is a risk that the substrate will be stiff and easy to loose. In addition, when the fiber which comprises a fiber structure has many types, the value which carried out the weighted average of those single yarn fineness shall be used for this fineness.

  For example, the fiber structure is obtained by mixing the main fiber and the heat-adhesive composite short fiber, and heat-treating the heat-bonded composite short fibers so that the heat-adhesive composite short fibers intersect with each other and the fixing points. A fiber structure is formed in which the heat-bonded fixing points are scattered in a state where the heat-adhesive composite short fibers and the main fibers intersect.

  The fiber arrangement direction in the fiber structure may be either the horizontal direction using the cross layer after the card machine or when the web is folded so that it is arranged vertically with respect to the thickness. In view of the stability of the structure of the product produced stably, it is more preferable that the fibers are arranged in the thickness direction.

In the fiber structure thus obtained, the density needs to be in the range of 0.005 to 0.10 g / cm ³ (preferably 0.02 to 0.08 g / cm ³ ). When the density is greater than 0.10 g / cm ³ , it is not preferable because it is hard and has a board shape, and sufficient sound absorption is not obtained. On the other hand, if the density is less than 0.01 g / cm ³ , it becomes unsatisfactory because it becomes a fluffy state and the handleability decreases.

  In the sound absorbing structure of the present invention, it is preferable that the weight ratio of the nonwoven fabric to the fiber structure is in the range of (the former: the latter) 20:80 to 1:99. If the weight ratio of the nonwoven fabric is larger than 20% by weight, sound energy may be reflected on the nonwoven fabric surface.

  There is no particular limitation on the method for integrating the nonwoven fabric and the fiber structure. Adhesion with a binder component in the fiber structure is also possible. However, when adhesiveness is required, it is possible to use a method currently used. A method using a powdery binder, a spider web-like low melting point fiber sheet (Nittobo, Spunfab) and the like can be used.

  In the sound absorbing structure thus obtained, a layer made of a nonwoven fabric is arranged on the sound source side. As a result, the sound absorption effect of the nonwoven fabric having a specific basis weight and air permeability and the sound absorption effect of the fiber structure having a specific density, thickness, and fineness can be widely used from low to high frequencies without impairing lightness and form stability. And good sound absorption is obtained.

  Note that the sound absorbing structure of the present invention may be subjected to dyeing or raising. Furthermore, a known functional process such as a water repellent process, a flameproof process, a flame retardant process, or a negative ion process may be added.

Next, although the Example and comparative example of this invention are explained in full detail, this invention is not limited by these. In addition, each measurement item in an Example was measured with the following method.
<Thickness>
The thickness (mm) was measured according to JISL1096. The average value was calculated with n = 5.
<Air permeability>
The air permeability (cc / cm ³ / sec) was measured according to JIS L1096 6.27.1 (Fragile method). The average value was calculated with n = 5.
<Melting point, softening point>
A Du Pont thermal differential analyzer model 990 was used and measured at a temperature increase of 20 ° C./min to obtain a melting peak. If the melting temperature is not clearly observed, the melting point is the temperature at which the polymer softens and starts to flow (softening point) using a trace melting point measuring device (manufactured by Yanagimoto Seisakusho). In addition, the average value was calculated | required by n number 5.
<Density>
The density (g / cm ³ ) was measured according to JISL1097. The average value was calculated with n = 5.
<Sound absorption characteristics>
Based on JISA1405, the normal incident sound absorption coefficient of building materials by the pipe method was measured at 1/3 octave center frequencies of 1000 Hz, 2000 Hz, and 4000 Hz. The average value was calculated with n = 5.
<Simple molding test>
The sound absorbing structure was preheated at 160 ° C. for 5 minutes, and then a molding test was performed (cold press) using a metal mold (room temperature) having an uneven structure. Three testers made a five-step judgment based on the appearance of the finished sample.
5: Best moldability (no wrinkles)
4: Good formability (small wrinkles enter)
3: Formability average (with slightly larger wrinkles)
2: Formability is bad (wrinkles are considerably included)
1: Worst formability (contains many wrinkles)

[Example 1]
(Thin leaf nonwoven fabric)
Prepared a short stretched polyethylene terephthalate fiber with a single fiber fineness of 0.1 dtex and a fiber length of 3 mm and an unstretched polyethylene terephthalate short fiber with a single fiber fineness of 0.2 dtex and a fiber length of 3 mm at a weight ratio of 60/40. A 10 g / m ² wet paper was obtained using a paper machine and then heat treated with a Yankee dryer (135 ° C.) to obtain a uniform thin-leaf nonwoven fabric.
(Fiber structure)
Single fiber fineness 2.2dtex, fiber length 51mm stretched polyethylene terephthalate single fiber (main fiber), polyethylene terephthalate (melting point 256 ° C) at the core, terephthalic acid and isophthalic acid mixed at 60/40 (mol%) Copolymer polyethylene terephthalate (softening point 110 ° C.) composed of a diol component obtained by mixing 85/15 (mol%) of ethylene glycol and diethylene glycol with a sheath portion and a sheath / core weight ratio of 50 / A core-sheath-type heat-adhesive composite short fiber (single yarn fineness 4.4 dtex, fiber length 51 mm) obtained by spinning by a conventional method so as to be 50 was blended at a weight ratio of 70/30, A uniform web was obtained. Next, the web was heat-treated at 160 ° C. for 10 minutes using a hot-air circulating dryer to obtain a fiber structure (weight per unit area 150 g / m ² , thickness 10 mm, density 0.015 g / cm ³ ).
(Stacked integration)
A high-performance sound-absorbing structure in which the two were integrated was obtained by laminating and heat-treating them between them via a heat-bonding sheet (Nittobo's spunfab basis weight 15 g / m ² ). And when the thin-leaf nonwoven fabric side was arranged on the sound source side and evaluated, it showed excellent performance. The evaluation results are shown in Table 1.

[Example 2]
(Thin leaf nonwoven fabric)
Prepared a 60/40 weight ratio of stretched polyethylene terephthalate short fibers with a single fiber fineness of 0.06 dtex and fiber length of 3 mm and unstretched polyethylene terephthalate short fibers with a single fiber fineness of 0.2 dtex and a fiber length of 3 mm. A 25 g / m ² wet paper was obtained using a paper machine and then heat treated with a Yankee dryer (135 ° C.) to obtain a uniform thin-leaf nonwoven fabric.
A high-performance sound absorbing structure was obtained by using the same method for the fiber structure and integration except that only the thin-leaf nonwoven fabric was changed to the above for Example 1. The evaluation results are shown in Table 1.

[Example 3]
(Fiber structure)
Single fiber fineness 6.6 dtex, fiber length 51mm stretched polyethylene terephthalate single fiber (main fiber), polyethylene terephthalate (melting point 256 ° C) in the core, terephthalic acid and isophthalic acid mixed at 60/40 (mol%) Copolymer polyethylene terephthalate (softening point 110 ° C.) composed of a diol component obtained by mixing 85/15 (mol%) of ethylene glycol and diethylene glycol with a sheath portion and a sheath / core weight ratio of 50 / A core-sheath-type heat-adhesive composite short fiber (single yarn fineness 4.4 dtex, fiber length 51 mm) obtained by spinning by a conventional method so as to be 50 was blended at a weight ratio of 70/30, A uniform web was obtained. Next, the web was heat-treated at 160 ° C. for 10 minutes using a hot-air circulating dryer to obtain a fiber structure (weighing 2000 g / m ² , thickness 20 mm, density 0.010 g / cm ³ ).
With respect to Example 1, except that only the fiber structure was changed to the above, a thin high-performance sound absorbing structure was obtained using the same method for thin-leaf nonwoven fabric and integration. The evaluation results are shown in Table 1.

[Example 4]
(Thin leaf nonwoven fabric)
Prepared a short stretched polyethylene terephthalate fiber with a single fiber fineness of 0.3 dtex and a fiber length of 3 mm and an unstretched polyethylene terephthalate short fiber with a single fiber fineness of 0.2 dtex and a fiber length of 3 mm at a weight ratio of 60/40. A 10 g / m ² wet paper was obtained using a paper machine and then heat treated with a Yankee dryer (135 ° C.) to obtain a uniform thin-leaf nonwoven fabric.
A high-performance sound absorbing structure was obtained by using the same method for the fiber structure and integration except that only the thin-leaf nonwoven fabric was changed to the above for Example 1. The evaluation results are shown in Table 1.

[Comparative Example 1]
(Thin leaf nonwoven fabric)
Prepared 60/40 by weight ratio of stretched polyethylene terephthalate short fibers with a single fiber fineness of 0.6 dtex and fiber length of 3 mm and unstretched polyethylene terephthalate short fibers with a single fiber fineness of 1.2 dtex and fiber length of 3 mm. A 50 g / m ² wet paper was obtained using a paper machine and then heat treated with a Yankee dryer (135 ° C.) to obtain a uniform thin leaf nonwoven fabric.
For Example 1, except that only the thin-leaf nonwoven fabric was changed to the above, the fiber structure and integration were measured using the same method. The evaluation results are shown in Table 1.

[Comparative Example 2]
(Thin leaf nonwoven fabric)
An acid component in which a stretched polyethylene terephthalate short fiber having a single fiber fineness of 0.3 dtex and a fiber length of 3 mm and polyethylene terephthalate (melting point: 256 ° C.) are mixed with terephthalic acid and isophthalic acid at 60/40 (mol%); Copolymer polyethylene terephthalate (softening point 110 ° C.) composed of a diol component obtained by mixing ethylene glycol and diethylene glycol at 85/15 (mol%) in the sheath portion so that the sheath / core weight ratio is 50/50. A core-sheath type heat-adhesive composite short fiber (single yarn fineness of 1.7 dtex, fiber length of 5 mm) obtained by spinning by a conventional method was prepared at a weight ratio of 70/30, and a regular inclined short net paper machine was used. After obtaining 25 g / m ² of wet paper, heat treatment was performed with a Yankee dryer (135 ° C.) to obtain a uniform thin leaf nonwoven fabric.
For Example 1, except that only the thin-leaf nonwoven fabric was changed to the above, the fiber structure and integration were measured using the same method. The evaluation results are shown in Table 1.

[Comparative Example 3]
Measurement was carried out using the same method as in Example 1 except that a polyethylene terephthalate long fiber nonwoven fabric (spunbond, 50 g / m ² ) was used instead of the thin leaf nonwoven fabric. The evaluation results are shown in Table 1.

[Comparative Example 4]
In Example 1, it measured using the method similar to Example 1 except having used the ultrafine nonwoven fabric (melt blow, 15 g / m < ² >) made from a polypropylene instead of a thin-leaf nonwoven fabric. The evaluation results are shown in Table 1.

[Comparative Example 5]
Measurement was carried out only with the fiber structure used in Example 1 (without the nonwoven fabric on the surface). The evaluation results are shown in Table 1.

[Example 5]
(Wet spunlace nonwoven fabric)
Prepared with 100% stretched polyethylene terephthalate short fibers with a single fiber fineness of 0.1 dtex and a fiber length of 3 mm, and obtained a wet paper of 30 g / m ² using a regular inclined short net paper machine, then using a high-pressure water stream After intertwining the fibers, heat treatment was performed with an air-through dryer (100 ° C.) to obtain a uniform wet spunlace nonwoven fabric.
(Fiber structure)
Single fiber fineness 2.2dtex, fiber length 51mm stretched polyethylene terephthalate single fiber (main fiber), polyethylene terephthalate (melting point 256 ° C) in the core, terephthalic acid and isophthalic acid mixed at 60/40 (mol%) Copolymer polyethylene terephthalate (softening point 110 ° C.) composed of a diol component obtained by mixing 85/15 (mol%) of ethylene glycol and diethylene glycol with a sheath portion and a sheath / core weight ratio of 50 / A core-sheath-type heat-adhesive composite short fiber (single yarn fineness 4.4 dtex, fiber length 51 mm) obtained by spinning by a conventional method so as to be 50 was blended at a weight ratio of 70/30, A uniform web was obtained. Next, the web was heat-treated at 160 ° C. for 10 minutes using a hot-air circulating dryer to obtain a fiber structure (weight per unit area 150 g / m ² , thickness 10 mm, density 0.015 g / cm ³ ).
(Stacked integration)
A high-performance sound-absorbing structure in which the two were integrated was obtained by laminating and heat-treating them between them via a heat-bonding sheet (Nittobo's spunfab basis weight 15 g / m ² ).
When the thin non-woven fabric side was placed on the sound source side and evaluated, it showed excellent performance. Moreover, the moldability was also excellent. The evaluation results are shown in Table 2.

[Example 6]
(Wet spunlace nonwoven fabric)
Prepared with 100% stretched polyethylene terephthalate short fibers with a single fiber fineness of 0.06 dtex and a fiber length of 3 mm, and obtained a 25 g / m ² wet paper using a regular slanted short net paper machine, then using a high-pressure water stream After intertwining the fibers, heat treatment was performed with an air-through dryer (100 ° C.) to obtain a uniform wet spunlace nonwoven fabric.
In Example 5, only the wet spunlace nonwoven fabric was changed to the above, and a fiber structure and integration were obtained using the same method to obtain a high performance sound absorbing structure. When the thin non-woven fabric side was arranged on the sound source side and evaluated, it showed excellent performance. Moreover, the moldability was also excellent. The evaluation results are shown in Table 2.

[Example 7]
(Fiber structure)
Single fiber fineness 6.6 dtex, fiber length 51mm stretched polyethylene terephthalate single fiber (main fiber), polyethylene terephthalate (melting point 256 ° C) in the core, terephthalic acid and isophthalic acid mixed at 60/40 (mol%) Copolymer polyethylene terephthalate (softening point 110 ° C.) composed of a diol component obtained by mixing 85/15 (mol%) of ethylene glycol and diethylene glycol with a sheath portion and a sheath / core weight ratio of 50 / A core-sheath-type heat-adhesive composite short fiber (single yarn fineness 4.4 dtex, fiber length 51 mm) obtained by spinning by a conventional method so as to be 50 was blended at a weight ratio of 70/30, A uniform web was obtained. Next, the web was heat-treated at 160 ° C. for 10 minutes using a hot air circulation dryer to obtain a fiber structure (weight per unit area: 200 g / m ² , thickness: 20 mm, density: 0.010 g / cm ³ ).
Except that only the fiber structure was changed to the above in Example 5, a thin sound nonwoven fabric and integration were obtained using the same method to obtain a high performance sound absorbing structure. When the thin non-woven fabric side was arranged on the sound source side and evaluated, it showed excellent performance. Moreover, the moldability was also excellent. The evaluation results are shown in Table 2.

[Comparative Example 6]
(Thin leaf nonwoven fabric)
Prepared at a 60/40 weight ratio with a stretched polyethylene terephthalate short fiber with a single fiber fineness of 0.1 dtex and a fiber length of 3 mm and an unstretched polyethylene terephthalate short fiber with a single fiber fineness of 0.2 dtex and a fiber length of 3 mm. Using a paper machine, 30 g / m ² wet paper was obtained, and then heat treated with a Yankee dryer (135 ° C.) to obtain a uniform thin-leaf nonwoven fabric.
For Example 5, except for the thin-leaf nonwoven fabric, the sound absorbing structure was obtained using the same method for the fiber structure and the integration except that the above was changed. The evaluation results are shown in Table 2.

[Comparative Example 7]
(Thin leaf nonwoven fabric)
Preparation of 60/40 by weight ratio of stretched polyethylene terephthalate short fibers with a single fiber fineness of 0.1 dtex and fiber length of 3 mm and unstretched polyethylene terephthalate short fibers with a single fiber fineness of 0.6 dtex and fiber length of 3 mm. After obtaining 30 g / m ² wet paper using a paper machine, fibers were entangled with each other using a high-pressure water stream, and then heat treated with an air-through dryer (100 ° C.) to obtain a uniform wet spunlace nonwoven fabric. Got.
For Example 5, except for the non-woven fabric, the sound absorbing structure was obtained using the same method for the fiber structure and the integration except that the above was changed. The evaluation results are shown in Table 2.

  ADVANTAGE OF THE INVENTION According to this invention, the sound absorption structure which has a wide and favorable sound absorption characteristic from low frequency to high frequency without impairing lightweight property and form stability is provided, and the industrial value is very large.

Claims (10)

A non-woven fabric having a thickness of less than 5 mm is laminated on a fiber structure having a thickness of 5 to 50 mm, and the non-woven fabric is disposed on the sound source side, wherein the non-woven fabric is a wet papermaking A sound-absorbing structure, which is a nonwoven fabric produced by a method or a wet spunlace nonwoven fabric, and the air permeability of the nonwoven fabric is in the range of 15 to 100 cc / cm ³ / sec.   The sound-absorbing structure according to claim 1, wherein a single fiber fineness of a fiber constituting the nonwoven fabric is in a range of 0.01 to 2 dtex. The sound-absorbing structure according to claim 1 or ² , wherein the nonwoven fabric has a basis weight within a range of 5 to 80 g / m2.   The non-woven fabric is a non-woven fabric produced by a wet papermaking method, and the non-woven fabric is composed of polyester fibers and binder fibers, and the weight ratio of the polyester fibers to the binder fibers (the former: the latter) is 80: 20-20. The sound-absorbing structure according to any one of claims 1 to 3, which is within a range of 80.   The nonwoven fabric is a wet spunlace nonwoven fabric, the nonwoven fabric is composed of polyester fibers and / or binder fibers, and the weight ratio of the polyester fibers to the binder fibers (the former: the latter) is 100: 0 to 70:30. The sound-absorbing structure according to any one of claims 1 to 3, which is within a range.   5. The binder fiber according to claim 4, wherein the binder fiber is an unstretched fiber or a heat-adhesive conjugate fiber composed of a heat-fusion component and a fiber-forming thermoplastic polymer, at least the heat-fusion component being exposed on the fiber surface. Item 6. The sound absorbing structure according to Item 5.   The sound-absorbing structure according to any one of claims 1 to 6, wherein a single fiber fineness of a fiber constituting the fiber structure is in a range of 0.9 to 20 dtex. The sound-absorbing structure according to any one of claims 1 to 7, wherein a density of the fiber structure is in a range of 0.005 to 0.10 g / cm ³ .   The said fiber structure is comprised from a polyester-type fiber and a binder fiber, and the weight ratio of a polyester-type fiber and a binder fiber exists in the range of 90: 10-50: 50 (the former: latter). Sound absorbing structure according to any one of -8.   The sound-absorbing structure according to any one of claims 1 to 9, wherein a weight ratio of the nonwoven fabric to the fiber structure is within a range of (the former: the latter) 20:80 to 1:99.