JP2005105456A - Acoustic material for high temperature and acoustic structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic material for high temperature, keeping the shape without damaging the structure of a porous body constituted of fibers even in a high temperature atmosphere, and having effective acoustic characteristics; and to provide an acoustic structure for the high temperature. <P>SOLUTION: The acoustic material for the high temperature is obtained by using a composite twisted yarn obtained by subjecting a heat-resistant artificial inorganic amorphous staple fiber and a small amount of an organic fiber to blend spinning and reinforcing the resultant yarn with a heat-resistant reinforcing wire, and is in a shape of a cloth having 1.5-3 mm thickness, and 600-1,400 g/m<SP>2</SP>surface density. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sound-absorbing material and a sound-absorbing structure that can be used in a high-temperature atmosphere of about 350 ° C. to 1000 ° C.

  The practical maximum temperature of the inorganic fiber aggregate sound-absorbing material such as glass wool and rock wool, which has been most commonly used in the past, is about 350 ° C., depending on the heat resistance of the binder. Moreover, the practical maximum temperature of the aluminum fiber-based sound absorbing material is about 150 ° C., and it cannot be used as a sound absorbing material used in a high temperature condition of about 350 ° C. or higher, or has many practical disadvantages.

  Now, inorganic fiber aggregate sound-absorbing materials such as glass fiber and rock wool are made of glass fiber or molten mineral, and all of them are constant in the temperature range up to their transition point and softening point temperature. Although it has heat resistance, the binder for fixing each fiber of the inorganic fiber aggregate sound-absorbing material constituting the porous body is an organic polymer substance such as phenol resin, so that it is exposed to an atmosphere of 350 ° C. or higher. If this happens, decomposition and carbonization will start, and smoke and ignition will occur at higher temperatures, causing problems such as the separation of individual fibers from the inorganic fiber aggregate sound-absorbing material, separation and scattering, and collapse of the porous structure. So there is a big problem in practical use.

  Moreover, in order to solve the said subject, there exists an inorganic fiber aggregate sound-absorbing material made by the method which uses heat-resistant fibers, such as a glass fiber and ceramic fiber which carried out the silica process, as a base material, and does not use a binding material. These are formed by making the aggregate of the fiber bases into a certain thickness, performing needle processing, which is one of the non-woven fabric manufacturing methods, and entangled the short fibers in the thickness direction. Since this method does not use a binding material, there is no loss of the binding material at high temperatures, but because these heat-resistant fibers have a smooth, straight and short surface, the binding force between the fibers due to the entanglement between the fibers is weak. Since the porosity is not determined, it is extremely difficult to obtain a stable product as a sound absorbing material having an arbitrary thickness and surface density. Furthermore, since the fiber mutual bonding force of the sound absorbing material is not sufficient, the fiber is detached or scattered due to wind pressure or the like during use in a high temperature atmosphere.

  An object of the present invention is to solve the above-mentioned conventional problems, and to maintain the shape of a porous body composed of fibers even in a high-temperature atmosphere without breaking the structure and to have an effective sound-absorbing characteristic. It is to provide a material and a sound absorbing structure for high temperature.

  The inventors of the present invention are fiber aggregate porous bodies in which each fiber is not bonded by an organic polymer, and each fiber is not a loose bond due to entanglement or friction like a nonwoven fabric. Attention was paid to the presence of a fiber aggregate porous body in which a woven fabric (cloth shape) is formed by forming twisted yarns in which fibers are twisted together, and the fiber structure is further stabilized.

  That is, it is composed of a composite twisted yarn obtained by mixing and spinning short fibers of artificial inorganic amorphous fibers having heat resistance and a small amount of organic fibers according to claims 1 to 3, and further increasing the strength with various reinforcing wires. Textile fibers are known as heat-resistant packings and heat-insulating coating materials, but no use as a sound-absorbing material has been found so far.

  Accordingly, the present inventors have conducted extensive research such as measuring the sound absorption coefficient of the woven fabric obtained by changing the composition of the yarn as the starting material of the present invention, and the thickness and area density shown in claim 1. It was found that this product has good sound absorption characteristics. Furthermore, it is found that the sound absorption characteristics are greatly improved by burning and disappearing the organic fibers in the product in advance, and that the sound absorption characteristics are not deteriorated even if the product is exposed to a high temperature atmosphere for a long time. It came to.

The first aspect of the present invention is a woven fabric made of a composite twisted yarn in which short fibers of heat-resistant artificial inorganic amorphous fibers and a small amount of organic fibers are mixed and spun up with various reinforcing wires. Te, a thickness of 1.5 mm to 3 mm, and wherein the surface density of the cloth-like ^{600g / m 2 ~1400g / m 2} , a hot sound absorbing material.

  According to a second aspect of the present invention, there is provided a high-temperature sound-absorbing material characterized in that the porosity is improved by burning the organic fibers of the high-temperature sound-absorbing material described in the first aspect in advance.

  A third aspect of the present invention is characterized in that a high-temperature heat-resistant wire mesh is attached to one side of the high-temperature sound-absorbing material according to the first and second aspects using a heat-resistant wire. It is a high-temperature sound-absorbing material.

  According to a fourth aspect of the present invention, the sound absorbing material for high temperature according to any one of claims 1 to 3 is disposed in a flat plate shape or a curved surface on the sound source side through a rigid wall having heat resistance and an air layer. This is a high-temperature sound-absorbing structure.

  According to a fifth aspect of the present invention, the sound absorbing material for high temperature according to the first aspect or the second aspect is formed into a corrugated shape in the air layer portion of the sound absorbing structure for high temperature according to the fourth aspect. This is a high-temperature sound-absorbing structure.

  By constituting the woven fiber according to the present invention, a cloth-like sound-absorbing material that is heat-resistant, thin, lightweight, self-holding, and excellent in sound-absorbing properties can be obtained economically and reasonably. Further, by firing in advance, a new sound absorbing material free from any concern about toxic gas generated during combustion due to the organic binder (binder) found in conventional sound absorbing materials can be obtained. Furthermore, since the design flexibility is increased by the thin and light characteristics of the cloth-like high-temperature sound-absorbing material, it is possible to provide a high-temperature sound-absorbing structure having excellent sound-absorbing characteristics.

The starting material of the composite twisted yarn used for the cloth-like high-temperature sound-absorbing material (woven fabric) of the present invention is composed of short fibers of artificial inorganic amorphous fibers, organic fibers interposed between these short fibers, and reinforcing wires. Short fibers of artificial inorganic amorphous fibers are refractory ceramic fibers, that is, the total of alumina (Al ₂ O ₃ ) and silica (SiO ₂ ) in the composition is 85% or more, and the fiber diameter is 2 to 4 μm, or It is called super wool, and is a heat-resistant short fiber having a fiber diameter of 3 to 5 μm, usually composed of silica (SiO ₂ ) and participating alkaline earths (CaO, MgO), usually having a fiber length of less than 10 mm. .

  As the intervening organic fiber, a short fiber obtained by cutting a fermentor or a crimp with a rayon fiber crimped to 6 to 25 mm is used. In addition to the rayon fiber, it can be replaced with short fibers such as vinylon, acrylic and polyester. However, the shape and material of the intervening organic fiber are additional elements in the production process and are not an essential problem in the present invention.

  For the reinforcing wire, filament yarn such as cotton yarn, long glass fiber yarn, stainless fiber yarn, alumina fiber yarn, etc. is used depending on the heat-resistant use conditions. In addition, if reinforcement in a high temperature atmosphere is required, in addition to the above filament yarn Various heat-resistant metal fine wires having a diameter of 200 μm or less, that is, stainless steel wires, nichrome wires, inconel wires, and the like are used.

  The cloth-like high-temperature sound-absorbing material of the present invention can be made into a woven fabric with a normal loom using the composite twisted yarn made of the material described in the preceding paragraph. That is, in the production of the composite twisted yarn, in the spinning process, first, organic fibers (15 to 20% by weight) are mixed into the short fibers of the artificial inorganic amorphous fibers, and then the steps of cotton battering, carding, and kneading are performed. A web and sliver (thick soft string-like fiber aggregate) is obtained. Next, the sliver is drawn by a roughing / spinning machine and twisted, and a filament yarn such as a long glass fiber yarn is inserted into a pre-reinforced base twisted yarn (called a raw yarn). Further, a plurality of the raw yarns and a heat-resistant metal fine wire such as a stainless steel wire are twisted to form a composite twisted yarn.

The composite twisted yarn obtained here can be made into a woven fabric having an arbitrary thickness and areal density with a normal loom. The areal density and thickness of the woven fabric are defined by the number of warp yarns and weft yarns constituting the woven fabric, yarn count (weight in unit length), thickness, and plastic deformability of the yarn. The mixing ratio of the artificial inorganic amorphous fiber (true specific gravity 2.4 to 2.7) and the intervening organic fiber (true specific gravity 0.9 to 1.2) is 80% by weight to 20% by weight. When the volume is set to several percent or less, a composite twisted yarn having plastic deformability with a thickness of 2 to 3 mm is obtained. A woven fabric having a thickness of 1.2 to 3.5 mm and an area density of 400 to 1700 g / m ² can be obtained using the composite twisted yarn.

These composite twisted yarns and fabrics made of the composite twisted yarns are fiber aggregate porous bodies. The composite twisted yarn is composed of artificial inorganic amorphous fiber (true specific gravity 2.6) and intervening organic fiber (true specific gravity 1), the mixing ratio thereof is 80% by weight to 20% by weight, and the thickness of the yarn is 2 mm. In the case of plastic deformation, if the volume of the entire reinforcing wire is ignored, the porosity of the composite twisted yarn is about 86%. Further, when the number of warp and weft yarns is adjusted using the composite twisted yarn so as to have a thickness of 2 mm and an area density of 1000 g / m ² , a porosity of about 78% is obtained. If the composite twisted yarn in this state is baked and the intervening organic fibers disappear, the burned-out part becomes new voids (micropores), and it is calculated that the apparent thickness does not change. ) Is 84%.

  As is apparent from Table 1 and FIG. 5 in the examples, the present inventors greatly improve the sound absorption characteristics by firing the untreated product (raw fabric) used in the present invention. Was found by measuring the sound absorption coefficient of the reverberation chamber method.

  In the first place, sound absorption of the high-temperature sound-absorbing material of the present invention is first manifested in a process in which sound waves pass through fine holes penetrating through the fiber assembly porous body. That is, when sound waves generated from a noise source enter the porous body, air particles in a large number of micropores vibrate and receive frictional resistance on the inner surface of the micropores, so that sound (vibration) energy is converted into thermal energy. It is said that sound absorption occurs when converted.

  Furthermore, the sound wave penetrating the sound absorbing material moves in the air layer of the sound absorbing structure, and collides with and reflects the heat-resistant rigid wall described later. The frequency indicating the maximum sound absorption rate is determined by the relationship between the interference phenomenon generated from the reflected wave and the incident wave and the mounting position of the sound absorbing material, that is, the size of the air layer.

  In Table 1 and FIG. 5, the reason why the sound absorption rate of the fired product is greatly improved compared to that before firing (before treatment) in any of the high-temperature sound-absorbing materials is that the firing treatment is performed as described above. Organic fibers disappear. The burned-out portion becomes a new void, and the increase in the void proportionally increases the number of micropores, that is, the pores penetrating through the fiber assembly porous body. As a result, it is presumed that the sound absorption rate is improved by increasing the frictional resistance on the inner surface of the fine hole against the sound wave.

Incidentally, the range of high temperature sound absorbing material of the present invention as specified in claim 1, and a thickness of 1.5 mm to 3 mm, is a surface density ^{600g / m 2 ~1400g / m 2} , are shown in Table 1, As is clear from comparison between Comparative Example 1 and Comparative Example 3 without firing treatment, the sound absorption characteristics of Comparative Example 3 having a sound absorbing material thickness of 3.5 mm exceeding the above range are inferior to those of Comparative Example 1. This reason is presumed to be caused by the fact that when the original thickness exceeds 3 mm, the number of fine pores penetrating the fiber aggregate porous body, that is, the sound absorbing material, decreases with an increase in fiber overlap.

  However, if the thickness and surface density of the high-temperature sound-absorbing material are below the range defined above, the mesh between the fibers constituting the sound-absorbing material is excessively open, so that it is difficult to maintain stability as a woven fabric.

  Moreover, as a result of holding the high-temperature sound-absorbing material in a preferable form specified in Example 1 and Comparative Examples 1 and 2 to be described later for 4 hours at an in-furnace temperature of 800 ° C., substantial dimensional change, shrinkage, cracking, No fiber detachment or the like occurred. In addition, no deterioration of the sound absorption characteristics was observed.

  The reverberation chamber method sound absorption coefficient shown in FIG. 5 is measured at room temperature (about 25 ° C.), but in a high temperature state, the sound absorption characteristics tend to move to a high temperature region as the sound speed increases due to temperature rise. . According to the calculation result, it moves 2/3 octaves at 500 ° C. and 1 octave right at 1000 ° C. However, in terms of sound absorption characteristics, it is presumed that there is no practical problem at all due to selection of the size of the air layer or the like.

  Next, the high temperature sound absorbing structure of the present invention will be described. The rigid wall having heat resistance means a rigid wall constructed of refractory bricks, irregular refractories, heat-resistant steel plates and the like. Further, a rigid wall is also included in which a heat insulating layer is formed of an indeterminate refractory or a ceramic fiber blanket on the inner surface of the steel plate, that is, the side facing the high-temperature sound absorbing material of the present invention. In addition, a steel-walled box-type structure, which includes a rigid wall that is continuously cooled by circulating air or water, is also included.

  The sound absorbing structure of the present invention is a structure in which the sound absorbing material for high temperature of the present invention is disposed on the sound source side through the rigid wall having heat resistance and an air layer. The thickness of the air layer is not particularly limited and may be appropriately selected depending on the intended sound absorption characteristics, but is usually about 50 to 150 mm. The air layer of the structure does not need to be constant in the structure, and may vary as appropriate within the above range depending on the construction layout. The cloth-like high-temperature sound absorbing material of the present invention may be arranged in a flat plate shape when the rigid wall is a flat plate and the air layer is constant. Further, when the rigid wall has an arch shape, it may be arranged so as to form an arch-shaped curved surface in accordance with the shape of the arch.

  When the cloth-like high-temperature sound-absorbing material of the present invention requires a higher wind pressure resistance, a stainless steel wire mesh is attached to the rigid wall side of the cloth-like high-temperature sound-absorbing material of the present invention to improve the rigidity. That's fine. The mesh of the metal mesh is not particular about the square shape, but in the case of a square, the length of one side is generally about 10 mm to 75 mm. The wire diameter of the wire mesh may be appropriately selected depending on the required wind-resistant pressure, but a wire having a diameter of 1.0 mmΦ to 4.0 mmΦ can be selected in relation to the length of one side of the wire mesh.

  By arranging the high-temperature sound absorbing material of the first or second aspect of the present invention in a corrugated form in the air layer portion of the high-temperature sound-absorbing structure, the sound absorption characteristics can be further improved. As shown in FIG. 4, the sound absorption coefficient in a specific frequency band can be adjusted by selecting the corrugated pitch (λ) and the size (X, Y) of the air layer in the peaks and valleys. .

(Corresponding to Claims 1 and 4) As the artificial inorganic amorphous fiber of the composite twisted yarn, a refractory ceramic fiber having a fiber diameter of ₂ to 4 μm and a composition of 46% by weight of Al ₂ O _{3 and} 54% by weight of SiO ₂ is used. It was. As the intervening organic fiber, a rayon fiber having a length of 12 mm and a fiber diameter of about 10 μm and having a crimp was used. The mixing ratio was 80% by weight of refractory ceramic fiber and 20% by weight of rayon fiber.

A single yarn of glass long fiber (ECG150 1/2) was used as the yarn reinforcing wire to obtain a yarn of 500 g / 1000 m. Further, one 150 μm stainless steel wire (SUS310S) and two of the above-mentioned raw yarns were twisted as metal fibers to form a composite twisted yarn of 1150 g / 1000 m. The composite twisted yarn was woven at a density (57 warps / 100 mm, 28 wefts / 100 mm), and a flat, high-temperature sound-absorbing material a, which is a woven fabric having a surface density of 1030 g / m ² and a thickness of 2 mm, was prepared.

  Now, as shown in FIG. 2B, a housing 5 having 2000 mm (length) × 500 mm (width) × 100 mm (depth) and having only the upper surface opened was prepared. The bottom member 6 (rigid wall) of the casing 5 is a stainless steel (SUS302) steel plate having a thickness of 1.6 mm. Further, the frame member of the side wall 7 is a combination of plate materials having a width of 25 mm (that is, the thickness of the side wall 7) formed into a box shape using the steel plate having a thickness of 1 mm. The high-temperature sound-absorbing material a4 was cut and fixed so as to close the upper surface (open surface) of the casing 5, and the high-temperature sound-absorbing structure 8 was manufactured. The sound absorption structure a8 was measured for the reverberation chamber method sound absorption coefficient according to JIS A1409-1998. The measurement result is shown by curve a in FIG. In both cases, relatively effective sound absorption characteristics were obtained in a frequency region of 315 Hz or higher.

(Corresponding to Claims 2 and 4) The fabric of Example 1 was fired. The firing process was performed by spreading the fabric vertically in the length direction, igniting from the lower end, firing the entire fabric, and removing contained rayon fibers and the like. The fabric dimensions after the baking treatment were not changed, and the mass was 860 g / m ² and the thickness was 1.9 mm. A flat plate-shaped sound absorbing material b for high temperature was prepared using this fiber.

  A housing 5 similar to the sound absorbing structure a is manufactured, and the high temperature sound absorbing material b4 is cut and fixed so as to close the upper surface (open surface) of the housing, and the high temperature sound absorbing structure b8. Was made. The sound absorption structure b is shown by a curve b in FIG. 5, similar to the result of measuring the reverberation chamber method sound absorption rate according to JIS A1409-1998 as in Example 1. Both exhibit effective sound absorption characteristics in a frequency band of 315 Hz or higher. In addition, it is apparent that the present embodiment, which has been subjected to the firing treatment in advance, has more effective sound absorption characteristics than the untreated high-temperature sound-absorbing structure a that is not subjected to the firing treatment of the first embodiment.

(Comparative Example 1) As a comparative example, another preferred embodiment of the high-temperature sound-absorbing material fabric of the present invention is the same specification material described in Example 1, using a refractory ceramic fiber for the composite twisted yarn, and intervening organic fiber A 500 g / 1000 m yarn was obtained by using rayon fiber and a glass long fiber yarn for the yarn reinforcing wire. Furthermore, one stainless steel wire and three of the above-mentioned raw yarns were twisted as metal fibers to form a composite twisted yarn of 1650 g / 1000 m. The composite twisted yarn was woven at a density of 40 warp yarns / 100 mm and 18 weft yarns / 100 mm to obtain a woven fabric having a mass of 1020 g / m ² and a thickness of 2.7 mm. When the sound absorption coefficient of the reverberation chamber method was measured for the woven fabric in the same manner as in Example 1, effective sound absorption characteristics were obtained as shown in Comparative Example 1 in Table 1.

(Comparative Example 2) The fabric of Comparative Example 1 was fired. The firing process was performed by spreading the fabric vertically in the length direction and igniting the bottom of the fabric to fire the entire surface of the fabric and removing the rayon fibers and the like. The dimensions of the fabric after the baking treatment remained unchanged, and the surface density was 855 g / m ² and the thickness was 2.6 mm. A flat plate-like sound absorbing material for high temperature was prepared using this fabric. The result of measuring the reverberation chamber method sound absorption rate of the woven fabric in the same manner as in Example 1 is shown in Comparative Example 2 of Table 1. Improvement of sound absorption characteristics was recognized by performing the baking treatment.

(Comparative Example 3) Further, as an unfavorable comparative example, a composite twisted yarn (1650 g / 1000 m) having the same specifications as described above is woven with a density: 54 warps / 100 mm, weft 28/100 mm, surface density 1510 g / m ² , A woven fabric having a thickness of 3.5 mm was obtained. When the sound absorption coefficient of the reverberation chamber method was measured in accordance with JIS A1409-1998, the result was unfavorable as shown in Comparative Example 3 in Table 1.

(Comparative Example 4) The fabric of Comparative Example 3 was fired. The firing process was performed by spreading the fabric vertically in the length direction, firing it from the lower end, firing the entire fabric, and removing contained rayon fibers and the like. The dimensions of the fabric after the baking treatment were not changed, and the surface density was 1270 g / m ² and the thickness was 3.3 mm. A flat plate-like sound absorbing material for high temperature was prepared using this fabric. The result of measuring the sound absorption coefficient of the reverberation chamber method in the same manner as in Example 1 is shown in Comparative Example 4 in Table 1. Although an improvement in sound absorption characteristics was recognized by applying the baking treatment, it did not reach a level that can be adopted as a sound absorbing material.

  (Corresponding to Claims 3 and 5) A stainless steel reinforced high temperature sound absorbing material c11 was prepared as described below. That is, as shown in FIG. 3, on one side of the fire-treated sound absorbing material b4, a wire mesh 9 made of stainless steel (SUS304), having a wire diameter of 2 mmΦ, a mesh shape of square, and a side of the grid of 30 mm is provided. Attached. For attachment, a wire 10 made of stainless steel (SUS304) and having a wire diameter of 1 mmΦ was used. The sound-absorbing material and the lattice were fixed by the wire 10 through the creases of the high-temperature sound-absorbing material at approximately every 10 lattice points of the wire mesh having a square lattice with a side of 30 mm, that is, approximately every 30 cm in the linear direction. (C) of FIG. 3 is explanatory drawing, and is not the figure fixed about every 10 lattice points.

  A casing 5 having a size of 2000 mm (length) × 500 mm (width) × 100 mm (depth), which is the same as in Examples 1 and 2, was opened. As shown in FIG. 4B, the high-temperature sound-absorbing material b that has been subjected to the firing treatment is placed in the casing 5 with a wave pitch λ (distance from the peak to the next peak) of 325 mm. The air layer in the mountain part (distance X from the lower part of the housing) is 100 mm, the air layer Y in the valley part is 50 mm, and the seismic amplitude of the waves is 50 mm. This is called a high-temperature wave-type sound absorbing material d13. In order to form a waveform as shown in FIG. 4B, a steel rod 12 made of stainless steel (SUS302) and having an outer diameter of 4 mmφ was used.

  The stainless steel reinforced high temperature sound absorbing material c11 is disposed on the high temperature wave type sound absorbing material d13, and is fixed to the casing to obtain a high temperature sound absorbing structure c14. FIG. 5 shows the result of measuring the sound absorption coefficient of the reverberation chamber method according to JIS A1409-1998 for the high temperature sound absorbing structure c14 in the same manner as in Examples 1 and 2. As apparent from the curve c in FIG. 5, the effect of improving the sound absorption characteristics is remarkable in the frequency region of 250 Hz or higher.

  Can be used for mufflers of automobiles with an atmospheric temperature of 350 ° C or higher, jet engine test operation rooms, engine rooms of large internal combustion engines such as ships, and silencers of cogeneration systems that are expected to develop rapidly in the future. There is sex.

It is explanatory drawing of a cloth-like high temperature sound-absorbing material, (a) is a figure which shows the planar structure. Moreover, (b) is a figure which shows the aa cross section of (a). It is a figure which shows the structure of the high temperature sound-absorbing structure a and b, (a) is the top view. Moreover, (b) is a figure which shows the bb cross section of (a). It is a figure which shows the structure of the stainless steel net strengthening type high temperature sound-absorbing material c, (a) is a flat plate-shaped high-temperature sound-absorbing material a or b, (b) is a figure which shows a stainless steel net. Moreover, (c) is a figure which shows the bb cross section in the state which accumulated (a) on the net | network of (b). It is a figure which shows the structure of the high-temperature sound-absorbing structure c, (a) is the top view. Moreover, (b) is a figure which shows the cc cross section of (a). It is a figure which shows the measurement result of the reverberation room sound absorption rate of the sound-absorption structure a for high temperature, b, and c.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Warp 2 Weft 3 Reinforcing wire 5 Case 6 Bottom member (rigid wall)
7 Side wall 8 High-temperature sound-absorbing structure a or High-temperature sound-absorbing structure b
9 Wire mesh 10 Wire 11 Stainless steel reinforced sound absorbing material for high temperature c
12 Steel bar 13 High-temperature wave type sound absorbing material d
14 High-temperature sound absorbing structure c
λ Pitch of wave-type sound absorbing material mountain X Air layer depth of mountain part Y Air layer depth of valley part

Claims (5)

A woven fabric made of a composite twisted yarn in which short fibers of artificial inorganic amorphous fibers with heat resistance and a small amount of organic fibers are mixed and increased in strength with various reinforcing wires, and the thickness is 1.5 mm to in 3 mm, and wherein the surface density of the cloth-like ^{600g / m 2 ~1400g / m 2} , high temperature sound absorbing material.   A high-temperature sound-absorbing material, wherein the porosity is improved by burning the organic fiber of the high-temperature sound-absorbing material according to claim 1 in advance and burning it.   A high-temperature sound-absorbing material, comprising a heat-resistant wire mesh having high rigidity attached to one surface of the high-temperature sound-absorbing material according to claim 1 or 2 using a heat-resistant wire.   A high-temperature sound absorbing material characterized in that the high-temperature sound-absorbing material according to any one of claims 1 to 3 is disposed in a flat plate shape or a curved surface on a sound source side through a rigid wall having heat resistance and an air layer. Structure.   The sound absorbing material for high temperature according to claim 4, wherein the sound absorbing material for high temperature according to claim 1 or 2 is formed into a wave shape in the air layer portion of the sound absorbing structure for high temperature according to claim 4. Structure.