JPH11327562A - Sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sound absorption performance of >=0.90 in average diagonal incident acoustic absorptivity by providing the surface layer part of an inorg. fiber mat with corrugated parts consisting of slopes inclined to the longitudinal surface of this inorg. fiber mat at the time of thermal pressure molding of the inorg. fiber mat in which a binder for the inorg. fibers is not yet cured. SOLUTION: The inorg. fiber mat 1 in which the binder for the inorg. fibers is not yet cured is subjected to thermal pressure molding and at the time of this thermal pressure molding, the surface layer part of the inorg. fiber mat 1 is provided with the corrugated parts 3 consisting of slopes 2 inclined to the longitudinal surface of the inorg. fiber mat 1. Namely, the corrugated parts 3 are formed along the outside surface 1a of the inorg. fiber mat 1 constituting the sound absorbing material 10 by the slopes 2 inclined at the angle within a range of 15 to 60 deg. with the inside surface in the longitudinal direction of the inorg. fiber mat 1. In such a case, mats, such as, for example, glass wool mats and rock wool mats, which are used as the sound absorbing material from heretofore, are usable as the inorg. fiber mat 1 constituting the sound absorbing material 10.

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 excellent sound absorbing properties, durability and aesthetic appearance, for example, used as a sound absorbing plate on a backside of a highway or a machine room. More specifically, the present invention relates to a sound absorbing material having sound absorbing properties suitable for sound absorption of a sound source obliquely incident on the sound absorbing material.

[0002]

2. Description of the Related Art In general, as a sound absorbing material made of inorganic fibers such as glass wool and rock wool, a plate-like body having a predetermined density, thickness, width and length (JIS A6301 standard) is used.
And cylindrical bodies (JIS A 9504 standard) and other JIS standard products, but their shapes are limited to flat plate-like or tubular shapes. On the other hand, in recent years, a sound absorbing material having a tubular shape or a combination of a tubular shape and a plate shape has been used in order to prevent noise on an elevated road or the like. It is preferable that the shape of the sound absorbing material used for the above-mentioned applications is such that it can exhibit the most sound absorbing performance with respect to the sound source, fits in a limited installation space of the sound absorbing material, and is also excellent in aesthetic appearance. However, as described above, the conventional inorganic fiber sound absorbing material is JIS
In most cases, a plate-shaped or cylindrical inorganic fiber sound-absorbing material is cut and attached, as disclosed in Japanese Patent Application Laid-Open No. 9-296533, as a conventional technology, since most of the materials have a plate shape or a cylindrical shape according to the standard. In addition, it was manufactured as a sound absorbing material having a desired shape.

In general, an inorganic fiber mat is formed by applying a binder to inorganic fibers, depositing the inorganic fibers on a cotton collecting conveyor, and curing the binder by applying heat and pressure to a predetermined thickness and density. The fibers are arranged in a direction parallel to the pressing surface, and a layered structure is formed. Therefore, when the sound wave is perpendicularly incident on the plane of the sound absorbing material made of the inorganic fiber mat, the sound wave is incident in a direction perpendicular to the arrangement direction of the inorganic fibers, and the sound wave is incident on the cut surface of the sound absorbing material. When incident perpendicularly, the sound wave is incident in a direction parallel to the arrangement direction of the inorganic fibers. In such a case, it is known that the former, that is, the sound wave is perpendicular to the plane of the sound absorbing material, has a higher sound absorbing effect than the latter, that is, the sound wave is perpendicular to the cut surface of the sound absorbing material. ing. However, in the conventional sound-absorbing material, since the cut surface of the glass wool flat plate is exposed on most of the outer peripheral surface along the longitudinal direction, the sound wave is perpendicular to the cut surface, that is, with respect to the arrangement direction of the glass wool. Therefore, there is a problem that the sound absorbing performance inherent to the glass wool sound absorbing material cannot be sufficiently obtained. The sound absorbing material is manufactured by cutting a plate-shaped glass wool sound-absorbing board and a tubular glass wool heat insulating tube, creating a plurality of members such as a glass wool flat plate and a semi-cylindrical member, and bonding these with an adhesive. Therefore, there is a problem that the operation is complicated, requires labor, is not suitable for industrial mass production, and increases the manufacturing cost. A molded sound absorbing material disclosed in Japanese Patent Application Laid-Open No. 9-296533 has been proposed as a molded sound absorbing material which is excellent in sound absorbing performance to solve the above problems and which can be industrially mass-produced. The invention of the above proposed is a columnar formed by molding an inorganic fiber mat, or a sound absorbing material having a cylindrical shape other than a cylinder,
Since the cut surface of the inorganic fiber is not exposed on the outer peripheral surface along the longitudinal direction of the sound absorbing material, the sound wave incident on the outer peripheral surface should be incident in a direction substantially orthogonal to the arrangement direction of the inorganic fibers. Accordingly, it is an object of the present invention to provide a molded sound absorbing material capable of maximizing the sound absorbing property of the inorganic fiber sound absorbing material.

[0004]

However, the above-mentioned sound-absorbing material needs to be formed in a batch type by winding up an inorganic fiber mat and putting it in a pair of molds, which is not suitable for mass production on an industrial scale. As before. In addition, when installed on the backside of an elevated road, it is necessary to hang it on an elevated road via a suspending member and spread a predetermined number of the molded sound absorbing materials, and as compared with installing a plate-shaped material, However, there is a problem in that the fixing fixture is heavy and requires a heavy one, and the mounting operation is complicated. Conventional sound-absorbing materials are evaluated based on either the reverberation chamber sound absorption coefficient or the normal incidence sound absorption coefficient. However, in places where the effects of reflected sound amplify the noise around the road, such as on the backside of an elevated road. In the evaluation,
The oblique incidence sound absorption coefficient, which is the sound absorption coefficient when incident at a certain angle with respect to the normal of the material surface similar to the noise properties at the site, is suitable. Is required to have a sound absorption performance of 0.90 or more. To satisfy the sound absorbing performance, it is not necessary to have a thickness up to 250 mm as in the above publication, but if it is a flat sound absorbing material, at least 150 mm or more is necessary. From the viewpoint of down, a sound absorbing material having a thinness of less than 100 mm and a sound absorbing property having an average oblique incidence sound absorbing coefficient of 0.90 or more is desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional sound absorbing material, and the binder for binding the inorganic fibers heats and presses the uncured inorganic fiber mat. It is characterized in that a corrugated portion is formed on the surface layer portion of the inorganic fiber mat at the time of heating and pressurizing, and the inclined portion is inclined with respect to the longitudinal surface of the inorganic fiber mat.
Further, the sound absorbing material according to claim 2 is characterized in that the inclined surface is formed within a range of 15 to 60 ° with respect to the longitudinal surface of the inorganic fiber mat. The sound absorbing material according to claim 3 is characterized in that the sound absorbing material according to claim 1 or 2 has a sound absorbing performance with an average oblique incidence sound absorbing coefficient of 0.90 or more. A sound absorbing material according to a fourth aspect is characterized in that, in the sound absorbing material according to any one of the first to third aspects, the wave portion is formed only with an inclined surface. According to a fifth aspect of the present invention, in the sound absorbing material according to any one of the first to fourth aspects, the sound absorbing material is coated with a protective material having an aperture ratio of 50% or more. I do.

[0006]

FIG. 1 shows an embodiment of a sound absorbing material according to the present invention. In FIG. 1, reference numeral 1 denotes an inorganic fiber mat constituting a sound absorbing material 10; The corrugated portion 3 is formed by an inclined surface 2 inclined along the surface 1a at an angle in the range of 15 to 60 ° with respect to the longitudinal surface of the inorganic fiber mat 1. In the present invention,
As the inorganic fiber mat 1 constituting the sound absorbing material 10, for example, a material conventionally used as a sound absorbing material such as a glass wool mat and a rock wool mat can be used. Among them, glass wool mats are lighter than rock wool mats, for example, are excellent in rigidity per unit area, and are difficult to shot, etc., so that the fiberization rate is high, and therefore, the sound absorption performance is also excellent, Particularly preferred.

The amount of the binder to be applied to the inorganic fiber mat is determined in consideration of the curing time and the rigidity after the formation.
The content is preferably 4 to 12% by weight. As the binder, a binder mainly containing a thermosetting resin such as a phenol resin is preferably used.

The unit weight (basis weight) of the inorganic fiber mat containing an uncured binder may be the same as that generally used for a sound absorbing material or a heat insulating material.の も の 4000 g / m ² can be used.

The sound-absorbing material 10 of the present invention uses a curing furnace (heat-press molding) so that the inorganic fiber mat 1 containing the uncured binder does not come out on the outer peripheral surface along the longitudinal direction. Manufacturing the sound-absorbing material 10 having the corrugated portions 3 by conveying the material by a line into a furnace, applying predetermined unevenness to the pressure belt, aerating hot air, and molding by heating and pressing to harden the binder. Can be. The surface layer 1 of the inorganic fiber mat 1 is formed by forming irregularities during the heating and pressing.
The fiber direction of a is pressed against the unevenness of the pressure belt and aligned in parallel along the waveform, and as a result, the incident pulse of the sound to be absorbed easily becomes perpendicular to the fiber direction. If the surface is cut by a cutter or the like after the heat and pressure molding, the incident cross section is likely to be parallel to the fiber orientation, so that the sound absorption coefficient decreases, which is not preferable.

The density of the sound absorbing material 10 of the present invention may be appropriately selected according to the required sound absorbing performance.
It is preferably kg / m ³ .

The inorganic fiber mat 1 of the sound absorbing material 10 of the present invention
By making the inclined surface 2 of the wave portion 3 provided on the surface layer portion 1a have an angle in the range of 15 to 60 ° with respect to the longitudinal surface of the inorganic fiber mat 1, the average oblique incidence sound absorption coefficient is 0. 90 or more. The reason will be described with reference to FIG. 2 together with a method of measuring the oblique incidence sound absorption coefficient. In this measurement method, the oblique incidence sound absorption coefficient α (θ) of a test sample is measured by a technique using pulse sound. The oblique incidence sound absorption coefficient α (θ) is measured by changing the incident angle, and the oblique incidence sound absorption coefficient α (θ) obtained for each angle is averaged to evaluate the average oblique incidence sound absorption coefficient α. Specifically, as shown in FIG. 2A, the sound source speaker 20 is separated from the center of the test body 30 placed on the rigid body 21 by 2 m, and from a height of 1.8 m to 30 to the longitudinal plane of the test body 30. A pulse sound is incident at an angle of up to 90 ° at every 15 °, and the reflected sound is symmetrical to the speaker 20 at a distance of 2 m from the center of the specimen 30 and a height of 1.8 m.
Is collected by the microphone 22 arranged at the position. The surroundings of the test piece 30 were subjected to sound absorption processing so that only signals of the direct sound from the speaker 20 and the reflected sound from the test piece 30 were obtained. According to the test of the oblique incidence sound absorption coefficient, FIG.
As shown in FIG. 2 (b), when the light is obliquely incident on the conventional flat product, the light is obliquely incident on the fiber orientation of the material, and the sound absorption coefficient is low, so that the reflected sound is increased. As shown, by providing an inclined surface having an angle in the range of 15 to 60 °, an incident pulse is received at an angle that is as perpendicular as possible to the fiber orientation on the surface of the test specimen 30, so that the sound absorption coefficient increases, and at the same time, the reflected sound is reduced. It was confirmed that the sound was diffracted and incident on the sound absorbing material, and the reflected sound to the microphone could be reduced.

The sound absorbing material has a total thickness T1 of the inorganic fiber mat of 25 to 150 mm and a wave height T2 of 5 to 5 mm.
It is preferably 0 mm.

The sound absorbing material of the present invention is preferably covered with a waterproof film material. As the waterproof film material, a material that can prevent water absorption of the inorganic fiber mat by rainwater or the like and prevent deterioration of the inorganic fiber due to sunlight or the like without adversely affecting the sound absorbing performance of the inorganic fiber mat is preferably used. For example, it is preferable to use a fluororesin film such as an FTFE (ethylene tetrafluoride ethylene copolymer) film and a PVF (polyvinyl fluoride resin) film. It is preferable that the waterproof film material is formed into a tubular or bag-like shape large enough to wrap the sound-absorbing material by a method such as heat sealing, and the sound-absorbing material is put into the tube and covered.

As the air-permeable protective material used in the present invention, those which improve the strength against external force and the appearance without impairing the sound absorbing performance are preferable, and various porous materials can be used. Punched metal, expanded metal, wire mesh, foamed metal, metal fiber cloth, metal nonwoven fabric, glass cloth, foamed ceramics material woven from aluminum wire or stainless steel wire are preferably used. When the protective material is made of, for example, perforated metal, wire mesh, or the like, the porosity is 30%.
It is preferable to set it to 80%. In particular, it was found that when the aperture ratio was 50% or more, a large sound absorption characteristic was obtained at an oblique incidence sound absorption coefficient.

[0015]

EXAMPLES <Example> Unit area weight 3200 g / m ² ,
A glass wool mat with an uncured binder with an applied amount of resin binder of 80% by weight was molded with a concavo-convex belt conveyor in a heating and pressing molding furnace while a hot air temperature of 230 ° C. was ventilated for 8 minutes to obtain the shape shown in FIG. Average density of 32 kg / m ³ , total thickness of 100 mm, wave height of 25 mm,
A corrugated glass wool board with a slope of 60 degrees is formed from the glass wool board and cut to a size of 750.
× 1980mm sound-absorbing material was obtained and the open area was 68% on the outer surface.
Was provided to make a sound absorbing panel.

<Comparative Example 1> A commercially available glass wool sound-absorbing board having an average density of 32 kg / m ³ and a thickness of 150 mm was used.
A glass wool flat sound-absorbing material was obtained by cutting to 0 × 1980 mm, and a punching metal having an opening ratio of 68% was provided on the outer surface to obtain a sound-absorbing panel.

Comparative Example 2 A commercially available glass wool sound-absorbing board having an average density of 32 kg / m ³ and a thickness of 100 mm
The glass wool plate was cut into a glass wool plate by cutting to 0 × 1980 mm, and the glass wool plate was processed by a cutter to have a total thickness of 100 mm, a wave height of 25 mm, and a projection angle of 95 as in the example.
A corrugated sound absorbing material was obtained, and a punching metal having an opening ratio of 68% was provided on the outer surface to obtain a sound absorbing panel. The oblique incidence sound absorption coefficient of the sound absorbing materials of these examples and comparative examples was measured. The average oblique incidence sound absorption coefficient was 0.9 in Example, 0.92 in Comparative Example 1, and 0.2 in Comparative Example 2. Each measurement result of 85 was obtained.

In the embodiment, the cut surface of the glass wool is not exposed in the sound incident direction, so that the arrangement direction of the glass wool is substantially perpendicular to the sound incident direction and the double effect that the reflected sound is buffered is 100 mm. Despite the thinness, sound absorption performance with an average oblique incidence sound absorption coefficient of 0.9 or more was obtained. On the other hand, in Comparative Example 2 in which the arrangement direction of the glass wool is substantially parallel to the incident direction of the sound, the reflected sound is diffracted and is incident on the sound absorbing material. It can be seen that the sound absorption coefficient as in the example cannot be obtained because only is enlarged. Also,
Comparative Example 1 in which the incident pulse angle is approximately 30 to 90 °
Can obtain an average oblique incidence sound absorption coefficient of 0.9 or more equivalent to that of the embodiment, but the thickness of the sound absorbing material becomes 1.5 times, the weight becomes considerably heavy, and the cost increases economically, which is not preferable.

In the present embodiment, the corrugation is formed such that the apex is formed at the abutting portion between the inclined surfaces. However, the top of the corrugation may be formed as a flat surface.

[0020]

According to the sound-absorbing material of the present invention, since the cut surface of the inorganic fiber is not exposed on the outer peripheral surface along the longitudinal direction, the sound wave incident on the outer peripheral surface is directed to the arrangement direction of the inorganic fibers. Since the light is incident in directions substantially orthogonal to each other, it is possible to have sound absorption performance with an average oblique incidence sound absorption coefficient of 0.90 or more. Further, since it can be manufactured on-line, it is possible to mass-produce industrially. In addition, since it can be formed thin, the weight can be reduced, the sound absorbing material can be installed on the back of the road, and the installation work is simple.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sound absorbing material according to an embodiment of the present invention.

FIGS. 2 (a), (b) and (c) are illustrations of a sound absorbing effect of a sound absorbing material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sound absorbing material 2 Inclined surface 3 Wave part T1 Total thickness of sound absorbing material T2 Wave height of sound absorbing material

Claims (5)

[Claims] An inorganic fiber mat in which a binder for binding inorganic fibers is uncured is heated and pressed, and the surface layer of the inorganic fiber mat is inclined with respect to the longitudinal surface of the inorganic fiber mat during the heating and pressing. A sound-absorbing material characterized by having a wave portion formed by an inclined surface. 2. The sound absorbing material according to claim 1, wherein said inclined surface is formed within a range of 15 to 60 ° with respect to a longitudinal surface of the inorganic fiber mat. 3. The sound absorbing material according to claim 1, wherein the sound absorbing material has an average oblique incidence sound absorption coefficient of 0.90 or more. 4. The sound-absorbing material according to claim 1, wherein the wave portion is formed only by an inclined surface. 5. The sound absorbing material according to claim 1, wherein the sound absorbing material is covered with a protective material having an aperture ratio of 50% or more.