JPH10268871A - Sound absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sound absorber that has superior incombustibility and audio frequency band absorptivity and can be recycled, by constituting the sound absorber of >=2 kinds of specific fiber. SOLUTION: The sound absorber is formed of >=2 kinds of fiber and has measured sound absorptivity of >=30% at 400 hertz and >=70% at 100 hertz and also includes fiber A containing a thermoplastic polymer R1 having its fusion point lower than that of other fiber and incombustible fiber B. The fiber A consists preferably of two components of a thermoplastic polymer R1 and thermoplastic polymer R2 and specially of compound fiber of a core sheath type having the thermoplastic polymer R2 as a core part and the thermoplastic polymer R1 as a sheath part. Further, the weight ratio of the fiber A represented as R1/R2 is preferably 20/80 to 60/40 in terms of the shape holding property or cost of the sound absorber and the fusion point of the thermoplastic polymer R1 is preferably in the range of 80 to 170 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing material having flame retardancy, and more particularly to a sound-absorbing material having flame retardancy and sound absorbing properties, which can be recycled.

[0002]

2. Description of the Related Art Conventionally, glass wool, rock wool, aluminum fiber, lightweight foamed concrete, porous ceramic, and the like have been used as sound absorbing materials for vehicles, houses, and highway noise barriers. However, with these sound absorbing materials, satisfactory sound absorbing materials could not be obtained in terms of improving workability and preventing obstacles to the human body.

As a sound absorbing material, for example, Japanese Patent Publication No. Sho 6
JP-A-2-2155, JP-B-1-18183, JP-B-4-33478, JP-A-3-140185, and the like can also be used to form a fiber. It has been desired to further improve the sound absorption in the audible frequency band.

[0004] On the other hand, due to the two needs of environmental protection of the earth and efficient use of resources, the problem of treatment and reuse of industrial waste and general household waste has been increasing in importance, and many fields have been increasing. , Many people are interested. However, most used sound absorbing materials have been incinerated or landfilled, and recycling technology is still in the development stage.

Heretofore, recycling technologies for textile products can be roughly classified into the following three types.

[0006] The first is thermal recycling. In this method, the product is cut into an appropriate form, burned, and reused as in-house power generation and various types of heat energy. However, this method is not preferable from the viewpoint of resource reuse.

[0007] The second is material recycling. This method differs from the following chemical recycling in that the pellets are physically and mechanically pelletized. When this recycled pellet is reused, it is divided into two cases. One is to develop products as a new material in consideration of the mixture of various types of materials, which are reused in flower beds, bonsai pots, sidewalk decorative piles, and the like. The other is composed of 100% the same material as described in JP-A-5-219935 and JP-A-6-123052, and collected, pelletized,
This is the case of melting and reusing.

[0008] The third is chemical recycling. The chemical recycling that best matches the basic concept of recycling is chemical recycling, which collects products, decomposes them, and returns them to their original raw materials. However, fiber products are generally rarely produced as a single material, and the composition of the material is diverse. Therefore, an economical depolymerization system has not yet been successfully developed. Means for solving this problem is described in Japanese Patent Application Laid-Open No. 5-117441, for example, in the case of carpet products. As an auxiliary means for improving the efficiency of depolymerization, the carpet is fragmented, separated into small pieces containing nylon 6 which is a pile material and other small pieces by a separator, and the small pieces containing nylon 6 are supplied to a depolymerization system. This is a method of recovering ε-caprolactam as a raw material. However, even if the fiber product is divided into small pieces and separated by mechanical means such as a specific gravity difference due to a cyclone, it has been difficult to efficiently recycle the fiber product.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recyclable sound absorbing material which is excellent in flame retardancy and audible frequency band sound absorbing properties.

[0010]

The sound-absorbing material of the present invention has the following structure to solve the above-mentioned problems.

That is, a sound absorbing material composed of two or more kinds of fibers having a sound absorption coefficient of 400 measured by a method described later.
A sound absorption characterized by comprising a fiber A and a flame-retardant fiber B containing 30% or more at Hertz and 70% or more at 1000 Hertz and at least a melting point lower than the melting points of other fibers. Material.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sound absorbing material of the present invention will be described below in detail with reference to the drawings and by using embodiments.

The present invention is a sound-absorbing material composed of two or more kinds of fibers. The sound-absorbing coefficient measured by the method described later is 30% or more at 400 Hz, 70% or more at 1000 Hz, and at least the melting point. Contains a fiber A containing a thermoplastic polymer R1 lower than the melting point of other fibers and a flame-retardant fiber B.

From the viewpoint of imparting shape retention and durability of the sound absorbing material, the content of the fiber A containing the thermoplastic polymer R1 is preferably at least 10% by weight. Especially 15
The range of 〜60% by weight is more preferred. The fiber A is preferably composed of the two components of the thermoplastic polymer R1 and the thermoplastic polymer R2. The fiber A is a thermoplastic polymer in that it has low form stability and small particle generation due to a frictional effect when the sound absorbing material is used. A core-sheath type conjugate fiber having the combined R2 component as the core and the thermoplastic polymer R1 component as the sheath is particularly preferred. As the thermoplastic polymer R1, for example, in the case of a polyester, a polyolefin such as polyethylene, polypropylene, ethylene propylene copolymer, ethylene butene copolymer, ethylene vinyl acetate copolymer or olefin copolymer, polyhexamethylene terephthalate Selected from thermoplastic polymers such as polyesters such as polyhexamethylene butylene terephthalate, polyhexamethylene terephthalate isophthalate or copolymerized polyesters,
At least one polymer can be used. R2
Is not particularly limited, for example, terephthalic acid, 2,6
Polyesters such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene 2,6-naphthalate having naphthalene dicarboxylic acid or an ester thereof as a main dicarboxylic acid component and ethylene glycol or tetramethylene glycol as a main glycol component can be used.

When the fiber A is of a nylon type, for example, the thermoplastic polymer R2 component may be nylon 6 and the thermoplastic polymer R1 component may be nylon 6 and nylon 66 to lower the melting point. Can be used.

In the selection of the thermoplastic polymer R1, it is preferable that the melting point of the fibers other than the fiber A and the thermoplastic polymer R2 is lower than that of the lowest melting point, and is lower by 20 ° C. or more from the viewpoint of thermal adhesion. Preferably, the temperature is lower by at least 50 ° C.

Further, the melting point of R1 is preferably in the range of 80 to 170 ° C., more preferably in the range of 100 to 170 ° C., from the viewpoint of the effect of adhesion and prevention of thermal deterioration.

The weight ratio represented by R1 / R2 in the fiber A is preferably in the range of 20/80 to 60/40 from the viewpoints of shape retention, durability and cost of the sound absorbing material. In the fiber A, if necessary, R1, R
In addition to pigments other than 2, such as titanium oxide and carbon black, various antioxidants, anti-coloring agents, light-proofing agents, antistatic agents and the like may of course be added. Such a fiber A can be produced by an ordinary composite spinning method.

Next, in order to improve the sound absorbing property of the sound absorbing material of the present invention, the fiber A preferably has a mechanical crimp or the like. The number of crimps is preferably in the range of 3 to 10 peaks / 25 mm, and the degree of crimp is preferably in the range of 5 to 30%. Further, in order to improve the sound absorbing property, the fineness of the fiber A is preferably small, but from the viewpoint of processing stability in the manufacturing process of the sound absorbing material, the fineness is 0.2 to 30 denier, and the fiber length is as short as 10 to 100 mm. Fibers are preferably used. The sound absorbing material of the present invention needs to contain the flame retardant fiber B as a constituent fiber.

There is a problem that flame retardancy cannot be imparted unless the flame retardant fiber B is contained. The method of imparting flame retardancy to fibers may be a method of kneading a flame retardant component into a polymer,
A method in which the flame retardant component is applied by post-processing may be used. In terms of flame retardancy, compounds containing elements such as phosphorus, halogen, and antimony in the fiber can be preferably used. Of these, phosphorus-based compounds that do not generate harmful gases such as halogen gas during combustion are preferred.

When the flame-retardant fiber B is a polyester fiber and imparts flame retardancy by post-processing, a phosphazene compound having a high phosphorus content is preferred. Further, the phosphazene compound is more effective because it contains nitrogen having a flame retardant assisting action. As the phosphazene compound, a compound containing a linear or cyclic phosphazene compound represented by the following formula (I) or (II) is more preferable.

[0022]

Embedded image (X1 to X3 in the formula (I) represent an amino group or a phenoxy group, and Y1 to Y3 represent an amino group or a phenoxy group.)

Embedded image (X1 to X4 in the formula (II) represent an amino group or a phenoxy group, and Y1 to Y4 represent an amino group or a phenoxy group.) From the viewpoint of the efficiency of applying the phosphazene compound to the fiber, the total number of phenoxy groups in the phosphazene compound Is preferably two or more. In particular, in formula (I), the total number of phenoxy groups is preferably 2 or more and 6 or less. In the formula (II), the total number of phenoxy groups is preferably 2 or more and 8 or less.

When the flame-retardant fiber of the present invention is polyester,
Controlling the solubility of phosphazene compounds in water, which has been used as a water-soluble compound, in water with a substituent, increases the affinity for polyester, and at room temperature, modifies the compound into a solid that can be exhausted. It is preferable to use those that have been used.

As a method of applying a phosphazene compound to a polyester fiber to obtain a flame-retardant fiber, a method of applying a padding method or a spray method and performing dry curing may be used, or a method of performing a treatment in a bath similar to dyeing. May be.
The polyester flame-retardant fiber obtained by such a method shows high durability even by a treatment such as washing since the phosphazene compound is exhausted by the polyester fiber.

The amount of the phosphazene compound for obtaining flame retardancy depends on the phosphorus element content in the compound. For example, the amount of the phosphazene compound is set so that 0.2% or more of the phosphorus element is contained in the polyester fiber. Is preferred.

In actual use of the phosphazene compound, it is preferable to use it by dispersing it in water. The method of dispersing in water is not particularly limited, but from the viewpoint of dispersion efficiency, a phosphazene compound, a dispersant and water are mixed,
Stir and disperse. This dispersion is generally crushed and dispersed by a glass bead crusher.

As another method for finely dispersing the phosphazene compound in water, it may be dissolved in a solvent capable of dissolving the phosphazene compound, and then stirred and mixed with water to form an emulsion.

When the phosphazene compound is applied to the polyester by treatment in a bath, the treatment temperature is preferably 100 ° C. or higher. From the viewpoint of the exhaustion efficiency, at a temperature of 120 to 135 ° C., 3
It is preferable to carry out the treatment for 0 to 60 minutes, and then perform the usual washing and drying.

Further, it is also preferable to carry out a reduction cleaning after the treatment in the bath or a heat treatment after the drying.

On the other hand, when applying by a padding method or a spraying method and performing dry curing, after drying, 150 ° C.
This is a method of performing the exhaust treatment under the above atmosphere. From the viewpoint of providing uniform exhaustion, after drying at 100 to 120 ° C, 170 to 2
The exhaust treatment is preferably performed at a temperature of 00 ° C. or higher. The exhaust heat treatment time is preferably from 10 to 180 seconds or more.

The particle size of the phosphazene compound is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less, from the viewpoint of uniform exhaustion and stability of the dispersion.

The flame-retardant fiber B constituting the sound-absorbing material of the present invention is not particularly limited as long as it has a melting point higher than that of the thermoplastic polymer R1 of the fiber A. Further, in order to improve the sound absorbing property, it is preferable to have mechanical crimping or the like, the number of crimps is preferably in a range of 3 to 10 ridges / 25 mm, and the degree of crimp is preferably in a range of 5 to 30%.

Further, it is more preferable to have a crimp by side-by-side composite using a polymer having a viscosity difference at the time of spinning, a side-by-side composite using a different kind of polymer, or a three-dimensional structural difference crimp obtained by asymmetric cooling just below a die. .

In order to improve the sound absorbing property, the fineness is preferably small. However, from the viewpoint of processing stability in the process of manufacturing the sound absorbing material, the fineness is 0.2 to 30 denier and the fiber length is 10%.
Short fibers of １００100 mm are preferably used.

The fibers constituting the sound-absorbing material of the present invention may contain other fibers in addition to the fibers A and the flame-retardant fibers B. The other fibers preferably have a mechanical crimp or the like in order to improve the sound absorption, and the number of crimps is 3 to 10.
The range of peak / 25 mm is preferable, and the degree of crimp is preferably in the range of 5 to 30%. It is more preferable to have a crimp by a side-by-side composite using a polymer having a viscosity difference when spinning other fibers, a side-by-side composite using a different kind of polymer, or a three-dimensional structural difference crimp obtained by asymmetric cooling just below a die. . Further, in order to improve the sound absorbing property, the fineness of the other fibers is preferably fine, but from the viewpoint of processing stability in the process of manufacturing the sound absorbing material, the fineness is 0.2 to 30 denier, and the fiber length is 10 to 100 mm. Short fibers are preferably used.

Next, the sound absorbing material of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view schematically showing an example of the fiber arrangement of the sound absorbing material of the present invention.

The fiber arrangement of the fiber A, the flame-retardant fiber B and other fibers in the sound absorbing material is, for example, as shown in FIG. 1, parallel to the surface of the sound absorbing material as shown in FIG. It is preferable that they are arranged in a random direction in the plane. Further, it is more preferable that the sound absorbing material is arranged in a random direction within a plane parallel to the surface irohani, and the fiber axis direction is arranged substantially parallel to the surface irohani of the sound absorbing material. Generally, when a fiber is used as a sound absorbing material, the sound absorbing material has a higher density, a greater thickness, and a smaller fineness of the constituent fibers, indicating a better sound absorbing property. However, the density, thickness, and fineness of the constituent fibers of the sound absorbing material are naturally limited depending on the processing stability in the manufacturing process, the cost, or the place of use. For sound-absorbing materials of the same density, thickness and fineness of constituent fibers, by arranging the fiber arrangement in a random direction within a plane parallel to the surface of the sound-absorbing material as described above, for example, the fibers are put on a card to form a web. In addition, as compared to a web obtained by laminating the webs, the web exhibits excellent sound absorbing properties as compared with a web in which fibers are arranged in one direction.

The sound absorption coefficient is 100 in the human audible frequency band.
% Is preferable, but the sound absorption at 400 Hz is set to 30% or more as a representative value of the low frequency in the audible frequencies measured by the method described later. In addition, the sound absorption coefficient at 1000 Hz as a representative value of the treble is set to 70% or more. 4
If the sound absorption coefficient of 00 Hz is less than 30%, there is a problem that the sound absorption of low sound is low, and it is difficult to obtain a sufficient sound absorbing effect of low sound.
If the sound absorption at 1000 Hz is less than 70%, there is a problem that the sound absorption of high sounds is low, and it is difficult to obtain a sufficiently high sound absorption effect.

The conventional sound absorbing material is composed of various structure forming materials and adhesives. It is not easy to recycle the sound absorbing material composed of these various materials. In the sound-absorbing material of the present invention, in order to obtain an easily recyclable sound-absorbing material while maintaining the required quality of the sound-absorbing material, it is preferable that all the fibers constituting the sound absorbing material are made of fibers of the same polymer. When the fiber made of the same polymer of the sound absorbing material in the present invention is a polyester fiber, the heat absorbing and fixing property is excellent, the toxicity of the combustion gas is low, the recovered sound absorbing material is cut, opened, melted into pellets, and reused. Material recycling is possible, which is preferable. When the fiber made of the same polymer is nylon 6 fiber, the recovered sound-absorbing material is cut and spread, and the method disclosed in, for example, Japanese Patent Publication No. 42-18476 and Japanese Patent Application No. 6-127468. Depolymerization,
Purification, recovery as ε-caprolactam, and 6-caprolactam again
It can be reused as a raw material for nylon.

The fibers used in the present invention may contain various antioxidants, anti-coloring agents, light-proofing agents, antistatic agents, etc., as required, in addition to various pigments such as titanium oxide and carbon black. Is also good. Further, the cross-sectional shape of the fiber may be a round cross-section, an irregular cross-section such as a polygon, a multi-leaf, or an ellipse, or a hollow cross-section thereof.

Next, a method for producing the sound absorbing material of the present invention will be described. FIG. 2 is a schematic longitudinal sectional view schematically showing an example of a mold of an apparatus used in the method for producing a sound absorbing material of the present invention. A cotton-feeding machine, a cotton-mixing machine, and a fiber-spreading machine using fibers including at least the fiber A and the flame-retardant fiber B in a usual spinning process. The frame is filled by blowing with a gas such as an airflow from a cotton fan. In order to fill by blowing,
It is preferable that the mold has a moderate air permeability. For example, J
When measured with an IS L 1079-1966 Frazier-type air permeability tester, the air permeability is 5 to 200 c.
It is preferably in the range of c / cm ² · sec.

As such a mold, for example, an upper mold 2 and a lower mold 1 using a punched metal plate shown in FIG.
Can be used.

As a method of blowing into the air-permeable lower mold 1, first, fibers including at least the fiber A and the flame-retardant fiber B are mixed, opened, and blown from the blow opening 3. Next, the filling fiber is compressed with the air permeable upper mold 2, and the air permeable upper mold 2 is compressed and fixed at a target density. Further, the compression-fixed fibers can be heat-treated together with the air-permeable mold to substantially adhere a part of the contact points between the fibers A and between the fibers A and other fibers to fix the form. The temperature of the heat treatment may be a temperature at which the thermoplastic polymer R1 of the fiber A is melted and bonded. In general, the temperature is preferably equal to or higher than the melting point of the thermoplastic polymer R1, and is preferably 200 ° C or lower. The filling density may be appropriately selected according to the sound absorbing target of the sound absorbing material, but is generally preferably in the range of 0.01 to 0.1 g / cm ³ . If the density is less than 0.01 g / cm ³ , the sound-absorbing material tends to be too soft and the form stability tends to deteriorate, and if it exceeds 0.1 g / cm ³ , it may be disadvantageous in terms of cost.

[0045]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. The measuring methods of various characteristics described in the present invention are as follows.

(1) Sound absorption coefficient JIS A 1495 Normal incidence sound absorption measurement method (in-tube method)
It measured according to.

However, when the thickness of the sound absorbing material exceeded 30 mm, it was sliced into 30 mm and measured.

(2) Fineness The fineness was measured according to the method of JIS L 1015-7-51A.

(3) Average fiber length (cut length) Measured according to JIS L 1015A method (staple diagram method). (4) The number of crimps and the degree of crimp The number of crimps and the degree of crimp are as defined in JIS L 1015-7-12.
-1 and JIS L1015-7-12-2.

(5) Density sound absorbing material (vertical: 20 cm, horizontal: 20 cm, thickness: 1 c
m) was allowed to stand in an atmosphere of 20 ° C. × 65% RH for 24 hours, and the weight (w) was measured.

Density (g / cm ³ ) = w / 400 (6) Flame retardancy A part of the sound-absorbing material was taken out, opened with a hand opening machine into cotton, and measured according to the method of JIS L 1091D. .

[Example 1] A polyethylene terephthalate polyester having a melting point of 110 ° C copolymerized with 40 mol% of isophthalic acid as the thermoplastic polymer R1 and a normal polyethylene terephthalate having a melting point of 255 ° C as the thermoplastic polymer R2 were used. The spinning temperature is 285 ° C., the take-off speed is 1350 m / min, and the weight ratio represented by R1 / R2 is 50 /
50 thermoplastic polymer R2 as a core portion, thermoplastic polymer R1
Spinning undrawn yarn of concentric conjugate fiber with the sheath as
This undrawn yarn was drawn at a draw ratio of 3 times at a drawing bath temperature of 80 ° C., and mechanically crimped with a crimper. Furthermore, after drying with a heat setter at 70 ° C., a finishing oil is applied, cut into a cut length of 30 mm, the fineness is about 1.5 denier, the number of crimps is 4.7 / 25 mm, and the degree of crimp is 16. %, A fiber A having a surface layer having a melting point of about 110 ° C.

First, 20 parts by weight of a dispersant composed of a condensation product of naphthalenesulfonic acid and formaldehyde and 60 parts by weight of water were mixed with 100 parts by weight of tetraphenoxydiaminocyclotriphosphazene as a flame retardant, and stirred. After preparing the dispersion, the dispersion was pulverized with a glass bead pulverizer for 18 hours. After grinding, 10
% Carboxymethylcellulose solution (etherification degree 0.
(85%) 20 parts by weight were added to the dispersion and mixed thoroughly to obtain a 50% by weight dispersion of tetraphenoxydiaminocyclotriphosphazene.

Separately, an undrawn yarn is spun from ordinary polyethylene terephthalate having a melting point of 255 ° C. at a spinning temperature of 280 ° C. and a take-up speed of 1350 m / min. After stretching at ℃, mechanical crimping with a crimper and cutting to a cut length of 30 mm, the dispersion of tetraphenoxydiaminocyclotriphosphazene was applied by a spraying device, preliminarily dried at 120 ° C. for 3 minutes, and dried at 165 ° C. Dry exhaustion treatment was performed at 2 ° C. × 2 minutes to obtain an exhaustion amount of tetraphenoxydiaminocyclotriphosphazene of 7.2% owf, an exhaustion amount of phosphorus element of 1.22% owf, a fineness of about 1 denier, and a number of crimps of 4. 7 piles / 25mm, crimp degree 1
8.4% flame retardant polyester fiber B was produced.

25% by weight of the fiber A and 75% by weight of the flame-retardant polyester fiber B were blended and opened with a card, and punched on each side through a mold inlet 3 as shown in FIG. 1000 × 1000 × 10
It is blown into the lower mold 1 of 00 mm together with the air flow, and compressed by the upper mold 2 having each surface punched to a thickness of 25 mm.
Fixed. Using a heat setter used for setting the spun yarn together with the mold filled with the fiber and compressed, steam 130
After heat setting for 20 minutes at ℃, cool to a density of 0.05g
/ Cm ³ of a fiber sound absorbing material was produced.

The sound absorbing material is stable in form, and the constituent fibers are arranged in random directions in a plane parallel to the surface of the sound absorbing material, so that the 400 Hz sound absorbing coefficient is 43.5.
%, And 1000 Hz of sound absorption of 89.1%.

When the flame retardancy (the number of times of flame contact) was evaluated in three places, the results were 4, 3, and 3, indicating excellent flame retardancy.

The sound absorbing material was formed into a tile of 100 cm × 100 cm, mounted on an outdoor table, and left for one year.
The fiber was peeled off from the table and opened with an anti-hair machine. The opened fiber was melt-pelletized, melt-spun and stretched again to obtain a 6-denier, 51-mm polyester staple. The obtained staples were slightly lower in strength than commercially available polyester staples, but were sufficiently usable as wadding.

Comparative Example 1 The fiber A obtained in Example 1 was 25% by weight, and the other flame-retardant polyester fibers B obtained in Example 1 were produced without spraying the flame retardant with a spraying device. A sound absorbing material was produced in the same manner as in Example 1, except that 75% by weight of the fiber C was mixed.

The obtained sound-absorbing material has a stable form and the constituent fibers are arranged in random directions in a plane parallel to the surface of the sound-absorbing material.
It has excellent sound absorption of 2.2% and 1000 Hz sound absorption of 88.9%, but has flame retardancy (number of times of flame contact) of 3%.
When the parts were evaluated, they were 1, 1, and 1 with low flame retardancy.

Comparative Example 2 Using the fiber A and the fiber B obtained in Example 1, a density was set to 0.032 g / cm ³ at the time of producing the fiber sound-absorbing material. A fiber sound absorbing material was manufactured. The obtained sound-absorbing material was stable in form, and exhibited excellent flame retardancy with flame retardancy of 3, 4, and 3, but 400 Hz sound absorption was 20.5.
%, 1000 Hz sound absorption coefficient was 62.3%, which was inferior in sound absorption.

Example 2 20% by weight of the fiber A obtained in Example 1, 60% by weight of the flame-retardant polyester fiber B, and 20% by weight of the other fiber C obtained in Comparative Example 2 A fiber sound-absorbing material was produced in the same manner as in Example 1 except for the above.

The obtained sound-absorbing material has a stable form and the constituent fibers are arranged in random directions in a plane parallel to the surface of the sound-absorbing material, so that the 400-Hz sound absorbing coefficient is 44.1.
%, 1000 Hertz sound absorption is 89.2%, and the flame retardancy (the number of times of flame contact) is evaluated at three places. Was.

[0064]

According to the present invention, it has excellent flame retardancy,
It is possible to provide a sound-absorbing material having a fiber assembly structure that is excellent in audible frequency band sound absorption and that can be recycled.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view schematically showing an example of a sound absorbing material of the present invention.

FIG. 2 is a schematic vertical sectional view schematically showing an example of an apparatus used for producing the sound absorbing material of the present invention.

[Explanation of symbols]

 1: Lower mold 2: Upper mold 3: Gas inlet 4: Fiber

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 13/44

Claims (10)

[Claims] 1. A sound-absorbing material composed of two or more kinds of fibers, wherein the sound-absorbing coefficient measured by the method described in the text is 30% or more at 400 Hz, 70% or more at 1000 Hz, and A sound-absorbing material comprising a fiber A containing a thermoplastic polymer R1 and a flame-retardant fiber B having at least a melting point lower than the melting points of other fibers. 2. The fiber A is a core-sheath type composite fiber, wherein the thermoplastic polymer R1 is used as a sheath portion, and the thermoplastic polymer R2 having a melting point higher than the melting point of the thermoplastic polymer R1 is used as a core portion. The sound absorbing material according to claim 1, wherein 3. The sound-absorbing material according to claim 2, wherein the weight ratio of the fiber A represented by R1 / R2 is in the range of 20/80 to 60/40. 4. The sound-absorbing material according to claim 2, wherein the melting point of the thermoplastic polymer R1 is lower than the melting points of the other fibers and is in the range of 80 to 170 ° C. 5. The flame-retardant fiber B according to the following formula (I) or (I)
The sound absorbing material according to any one of claims 1 to 4, further comprising a linear or cyclic phosphazene compound represented by the formula (I). Embedded image (X1 to X3 in the formula (I) represent an amino group or a phenoxy group, and Y1 to Y3 represent an amino group or a phenoxy group.) (X1 to X4 in the formula (II) represent an amino group or a phenoxy group, and Y1 to Y4 represent an amino group or a phenoxy group.) 6. The sound absorbing material according to claim 5, wherein the total number of phenoxy groups in the phosphazene compound is 2 or more. 7. The sound-absorbing material according to claim 1, wherein the fineness of the constituent fibers is in the range of 0.2 to 30 denier. 8. The sound-absorbing material according to claim 1, wherein the constituent fibers are arranged in a random direction in one section of the sound-absorbing material. 9. The method according to claim 1, wherein the constituent fibers are all formed from a polyester polymer.
8. The sound absorbing material according to any one of 8. 10. A fiber according to claim 1, wherein all of the constituent fibers are formed from a nylon 6-based polymer.
8. The sound absorbing material according to any one of 8.