JP6478471B2 - Sound absorbing material - Google Patents

Description

  The present invention relates to a sound absorbing material made of a bubble board.

  Conventionally, as this type of sound absorbing material, a cap sheet having a plurality of protrusions for forming bubbles, and a back sheet that is attached to the open side of the protrusions of the cap sheet and forms a plurality of bubbles corresponding to the protrusions. And a liner sheet attached to the front end side of the protrusion of the cap sheet, an air chamber formed in each protrusion between the back sheet and the liner sheet, and each protrusion outside Various types of foam boards made by processing an air bubble board having a non-air chamber formed on the surface are known (see, for example, Patent Document 1 or 2 below).

  These sound-absorbing materials use a large number of small holes in a large number of air chambers from the back sheet side or the liner sheet side, thereby utilizing the air chambers and small holes as so-called Helmholtz resonators. In other words, the sound-absorbing effect is expressed by directing the surface with the small holes toward the sound source side, allowing sound emitted from the sound source to enter the air chamber through the small holes, and attenuating energy in the air chamber. . However, there is a problem that these sound absorbing materials do not have sufficient performance.

JP-A-10-245907 Japanese Utility Model Publication No. 57-107677

  As a result of investigation of the cause of the above-mentioned problems, the present inventors have found that the following phenomenon occurs. That is, the sound that has entered the air chamber through the small holes reverberates in the air chamber and attenuates energy, while at the same time, the projection of the cap sheet constituting the air chamber is vibrated, and the non-adjacent air chamber is adjacent to the projection. It will propagate to the air chamber. Unlike the air chamber in which a finite space is formed between the cap sheet and the back sheet, the non-air chamber has an infinite space communicating with the outside of the sound absorbing material at the end of the sound absorbing material. Therefore, the sound propagated to the non-air chamber through the projection after entering the air chamber from the small hole leaks from the end of the sound absorbing material, and thus the performance as the sound absorbing material is sufficient. I couldn't say that.

  Therefore, an object of the present invention is to provide a sound absorbing material made of a bubble board with improved sound absorbing performance.

The present invention employs the following configuration in order to solve the above-described problems. That is, the sound absorbing material according to the present invention includes a cap sheet having a plurality of protrusions for forming bubbles, and a bag that is attached to the open side of the protrusions of the cap sheet and forms a plurality of bubbles corresponding to the protrusions. At least a liner sheet attached to a tip side of the cap sheet protrusion, an air chamber formed in each protrusion between the back sheet and the liner sheet, and each protrusion A sound-absorbing material made of a bubble board having a non-air chamber formed outside, provided with a small hole for communicating the air chamber to the outside in a sound-absorbing material body made of the bubble board, and a sealing member provided so as to suppress the sound end surface of the sound absorbing material body propagated to the outside of the projection through the projection of the sound absorbing member is a body and the separate the cap sheet from leaking to the outside Ri sealed in characterized in that it blocks the communication between the non-air chamber and the outside at the end face.

  As a preferable aspect in the case where the sound-absorbing material main body includes a plurality of small holes and air chambers corresponding to the small holes, those having different sizes of the small holes may be mentioned. It is done.

  Further, as another preferable aspect in the case where the sound absorbing material main body is provided with a plurality of small holes and air chambers corresponding to these small holes, the volume of the air chambers is different from each other. Is mentioned.

  As a specific example of the sound-absorbing material main body, a back sheet and / or a liner sheet provided with a small hole that allows the non-air chamber to communicate with the outside.

The sound-absorbing material body is preferably a back sheet provided with the small holes.
If the sound-absorbing material main body includes a plurality of small holes provided in a back sheet and air chambers corresponding to the small holes, the sound absorbing material main body is provided around the small holes, which are openings that allow the air chambers to communicate with the outside. More preferably, the actual length of the opening is changed by varying the thickness of the backsheet.

  Since this invention is the above structures, it can provide the sound-absorbing material which uses the bubble board which improved the sound-absorbing performance as a material.

The external appearance perspective view which shows the sound-absorbing material concerning 1st Embodiment of this invention. The disassembled perspective view which shows the sound-absorbing material according to the same embodiment partially broken. The top view which shows the sound-absorbing material concerning the embodiment. AA line sectional view in FIG. The top view which shows the sound-absorbing material concerning 2nd Embodiment of this invention. BB sectional drawing in FIG. The top view which shows the sound-absorbing material concerning 3rd Embodiment of this invention. CC sectional view taken on the line in FIG. The top view which shows the sound-absorbing material concerning 4th Embodiment of this invention. DD sectional view taken on the line in FIG. Sectional drawing corresponding to FIG. 4 of the sound-absorbing material concerning 5th Embodiment of this invention. The external appearance perspective view which shows the sound-absorbing material concerning the 1st reference example relevant to this invention. The external appearance perspective view which shows the sound-absorbing material concerning the 2nd reference example relevant to this invention. The external appearance perspective view which shows the sound-absorbing material concerning the 3rd reference example relevant to this invention.

<First Embodiment (FIGS. 1 to 4)>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  The sound absorbing material 1 according to the present embodiment is used as a sound absorbing material for interiors in vehicles, buildings, assembly materials, and the like, and is made of a bubble board 4. Specifically, the sound absorbing material 1 is made of a synthetic resin bubble board 4 having a three-layer structure, and the sound absorbing material body 2 formed by cutting the bubble board 4 into a desired shape; The sealing member 3 that seals the end face 21 of the sound-absorbing material main body 2 is provided.

  The bubble board 4 includes a cap sheet 41 having a plurality of protrusions 47 for forming bubbles 44 and a plurality of bubbles 44 that are attached to the open side of the protrusions 47 of the cap sheet 41 and correspond to the protrusions 47. At least a back sheet 42 to be formed and a liner sheet 43 attached to the tip side of the protrusion 47 of the cap sheet 41 are provided.

  The cap sheet 41 has a three-dimensional structure including a large number of projections 47 having a circular shape in plan view, and the projections 47 are arranged in a line along the width direction and are staggered along the flow direction. Has been. The cap sheet 41 of this embodiment has a thickness dimension of about 950 μm where the protrusions 47 are not formed, a height dimension of the protrusions 47 of about 9 mm, and a diameter of about 16 mm. In addition, the preferable thickness dimension of the location where the protrusion 47 of the cap sheet 41 is not molded is 350 μm to 1700 μm, the preferable height dimension of the protrusion 47 is 4 mm to 20 mm, and the preferable diameter of the protrusion 47 is 5 mm to 25 mm. Degree.

  The back sheet 42 is a flat sheet that is attached to one surface of the cap sheet 41, and forms a large number of bubbles 44 that are sealed spaces in cooperation with the protrusions 47 of the cap sheet 41. The back sheet 42 of the present embodiment has the same thickness dimension as the cap sheet 41, specifically, a thickness dimension of 500 μm. In addition, the preferable thickness dimension of the back sheet 42 is 280 micrometers-1500 micrometers.

  The liner sheet 43 is a flat sheet that is attached to the other surface of the cap sheet 41. The liner sheet 43 of this embodiment has the same thickness dimension as the cap sheet 41 and the back sheet 42, specifically, a thickness dimension of 800 μm. In addition, the preferable thickness dimension of the liner sheet | seat 43 is 180 micrometers-1500 micrometers.

  Needless to say, the dimensions of the cap sheet 41, the back sheet 42, and the liner sheet 43 are not limited to those described above.

  Examples of the material resin for the bubble board 4 (hollow plate material) as described above include polyolefin resins such as polypropylene and polyethylene, polystyrene resins such as polystyrene, polyester resins such as polyethylene terephthalate, and polyamide resins such as nylon. Can be mentioned.

  An air chamber 45 formed in each projection 47 and a non-air chamber 46 formed outside each projection 47 are provided between the back sheet 42 and the liner sheet 43. Each of the air chambers 45 is formed in each of the protrusions 47. Specifically, the back of the cap sheet 41 that is in close contact with the inner surface of the protrusion 47 and the open side of the protrusion 47 of the cap sheet 41. It is a sealed finite space formed between the sheet 42. The bubble board 4 includes a plurality of air chambers 45, and the air chambers 45 are independent of each other. On the other hand, the non-air chamber 46 is formed outside the protrusions 47, and specifically, is in close contact with the outer surface side of the protrusion 47 of the cap sheet 41 and the tip end side of the protrusion 47 of the cap sheet 41. It is an infinite space formed between the liner sheet 43. The non-air chamber 46 communicates with the outside through the end of the bubble board 4. Thus, the bubble board 4 includes a single non-air chamber 46 in a portion other than the plurality of air chambers 45. The air chamber 45 is filled with air, and the non-air chamber 46 is also filled with air.

  The bubble board 4 as described above is cut into a predetermined size and shape to form the sound absorbing material body 2. Thus, the sound absorbing material 1 according to the present embodiment is manufactured using the bubble board 4, and the air is added to the sound absorbing material body 2 having the same structure as the whole or part of the bubble board 4. A small hole 22 that allows the chamber 45 to communicate with the outside is provided, and the end surface 21 of the sound-absorbing material body 2 is sealed by the sealing member 3 to block communication between the non-air chamber 46 and the outside at the end surface 21. ing.

  The small hole 22 is a through hole that is formed on the backsheet 42 side and communicates the air chamber 45 with the outside, and can form a Helmholtz resonator, which will be described later, in cooperation with the air in the air chamber 45. It has a size. The small holes 22 are provided one by one for the air chambers 45, and are arranged at an appropriate pitch on the back sheet 42 side. Specifically, each of the small holes 22 is formed so as to open at a central portion corresponding to each air chamber 45 in the backsheet 42, in other words, at an intermediate position of the finite space. It has a circular shape in plan view set to about 1.5 mm to 5.0 mm. In addition, as for the diameter of each small hole 22, 0.5 mm-5.0 mm are preferable. If it is smaller than 0.3 mm, it is difficult to process, and if it exceeds 12.0 mm, it is difficult to process, and the rigidity of the sound absorbing material 1 in the thickness direction is lowered. Of course, the diameter of the small hole 22 can be variously changed in accordance with the diameter of the protrusion 47. Further, as the method for forming the small hole 22, various methods such as drilling, needles, punching and the like can be applied.

  The said sealing member 3 is a plate-shaped thing which covers the end surface 21 (side surface) of the said sound-absorbing-material main body 2, Comprising: For example, it covers so that all the fore-edge end surfaces 21 of the four-sided sound-absorbing-material main body 2 which makes a planar shape rectangular shape. It is arranged in. The sealing member 3 is made of a synthetic resin made of materials such as those listed in the bubble board 4 and is joined to the end surface 21 of the sound absorbing material body 2 by heat fusion. Needless to say, the method of joining the sealing member 3 to the sound absorbing material body 2 may be by bonding using an adhesive or the like.

  Next, the sound absorbing action of the sound absorbing material 1 of the present embodiment will be described.

  The sound-absorbing material 1 of the present embodiment allows the communication between the air chamber 45 and the outside through the small hole 22, thereby forming an opening having a small diameter due to the small hole 22 and a cavity located behind the opening. The air chamber 45 is provided with a structure. And the air which exists in this opening part becomes a lump, and the said air chamber 45 acts like a spring with respect to this lump. In this way, the sound acting on the back sheet 42 side where the small hole 22 is provided is directly guided into the air chamber 45 formed by the cap sheet 41 and the back sheet 42 and reflected on the inner wall of the air chamber 45. The protrusion 47 of the cap sheet 41 is vibrated. The sound absorbing material 1 of the present embodiment uses the principle of a so-called Helmholtz resonator that obtains a sound absorbing effect by attenuating sound energy as described above.

  The Helmholtz resonator includes the cross-sectional area of the opening (that is, the opening area of the small hole 22), the actual length of the opening (that is, the thickness dimension of the back sheet 42 in which the small hole 22 is formed), and the volume of the air part ( That is, it is known that resonance motion occurs at a specific frequency in accordance with each element constituting the Helmholtz resonator, such as the size of the projection 47). Thus, the sound-absorbing material 1 of the present embodiment is a Helmholtz resonator having characteristics that depend on the cross-sectional area of the opening, the actual length of the opening, and the volume of the air, and by appropriately setting these values The sound absorption rate can be greatly improved.

  In the present embodiment, the end surface 21 of the sound-absorbing material main body 2 is sealed to block communication between the non-air chamber 46 and the outside of the end surface 21. The sound transmitted from the chamber 45 to the non-air chamber 46 can be prevented from leaking outside from the end of the non-air chamber 46. That is, the function of the sealing member 3 can form a huge sealed space in the non-air chamber 46 inside the sound absorbing material 1 as compared with the air chamber 45. The sound absorption performance can be improved as compared with the case where the end portion is opened to make an infinite space.

  As described above, according to the present embodiment, the cap sheet 41 having the plurality of protrusions 47 for forming the bubbles 44 and the protrusions 47 attached to the open side of the protrusions 47 of the cap sheet 41. And a liner sheet 43 attached to the front end side of the protrusion 47 of the cap sheet 41, and between the back sheet 42 and the liner sheet 43. The air bubble board 4 including the air chambers 45 formed in the protrusions 47 and the non-air chambers 46 formed outside the protrusions 47 is made of the air bubble board 4. The sound absorbing material body 2 is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside, and the end surface 21 of the sound absorbing material body 2 is sealed to form the non-air chamber 46 on the end surface 21. It was constructed of sound-absorbing material 1, characterized in that cuts off the communication between the parts.

  Therefore, even if the vibration of the sound absorbed in the air chamber 45 propagates to the non-air chamber 46 through the protrusion 47, the sound does not leak from the end of the sound absorbing material 1. Therefore, the sound absorption performance can be improved as compared with the conventional one.

  Further, the sound-absorbing material body 2 of the present embodiment includes a plurality of small holes 22 and air chambers 45 corresponding to the small holes 22, and the sizes of the small holes 22 are the same. In addition to easy manufacturing, it is possible to efficiently absorb sound having a frequency that requires noise countermeasures.

  Furthermore, since the volume of the air chamber 45 is the same, the sound-absorbing material body 2 of the present embodiment is relatively easy to manufacture, and the rigidity of the sound-absorbing material 1 can be made uniform.

  In particular, since the sound absorbing material main body 2 is provided with the small holes 22 only on one side, that is, the back sheet 42, the sound absorbing material main body 2 can be given directionality with respect to sound absorbing performance.

  In addition, since the back sheet 42 and the liner sheet 43 that form the outer layer of the present embodiment are flat plate-like materials each having a uniform thickness, workability during manufacturing is facilitated while maintaining sound absorption performance. be able to. Moreover, since the surface of the sound absorbing material 1 is flat, it has versatility as an interior material or the like.

  Furthermore, the sound absorbing material 1 of the present embodiment has a three-layer structure including a cap sheet 41 serving as a core layer, a back sheet 42 serving as a surface layer, and a liner sheet 43 serving as a back layer. It becomes difficult to cause bending deformation in the direction, and it is possible to provide rigidity. Therefore, according to the sound-absorbing material 1 of the present embodiment, the sound-absorbing material 1 has a sound-absorbing effect and also has a structural strength that firmly holds the flat plate shape, and is suitable for industrial fields that require rigidity. It is possible to provide a sound-absorbing material 1. That is, unlike a conventional sound absorbing material such as sponge or glass wool that needs to hold a structural member, the sound absorbing material 1 can be used as it is in a room, a vehicle interior, a cover of a noise source, or the like.

  Specifically, when the sound-absorbing material 1 according to the present embodiment is used as a part such as a motor case or an engine cover, an effect of further enhancing the silencing effect can be obtained by matching the frequency that requires noise countermeasures with the sound-absorbing frequency. I can expect. Further, by arranging the small holes 22 only on one side of the sound absorbing material 1, it is possible to improve the air tightness and to expect a sound insulation effect. In addition, for automobiles, it can be used for interior flooring, trunk boards, shelves, partitioning materials, and the like. In addition, in an electric vehicle that is expected to be widely used in the future, light weight and quietness are further required as a member. Therefore, the sound absorbing material 1 according to the present embodiment can be suitably used as an interior material or a sound deadening material. Furthermore, as for construction and civil engineering, it is highly possible to use it for wall materials and ceiling materials for house interiors, and as a soundproofing measure for construction work sites, factories, and offices, use the sound absorbing material 1 according to this embodiment. Is also possible.

  Moreover, since the end surface 21 of the sound-absorbing material body 2 is sealed with the sealing member 3 in the sound-absorbing material 1 of the present embodiment, foreign matters such as water and dust may enter the sound-absorbing material body 2. Can be suitably suppressed.

<Second Embodiment (FIGS. 5 and 6)>
Next, the sound absorbing material 1 according to the second embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

  The sound absorbing material 1 of the present embodiment is provided with small holes 22a and 22b that allow the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and seals the end face 21 of the sound absorbing material main body 2. The communication between the non-air chamber 46 and the outside at the end surface 21 is blocked. The sound-absorbing material body 2 includes a plurality of small holes 22a and 22b and air chambers 45 corresponding to the small holes 22a and 22b, and the sizes of the small holes 22a and 22b are different from each other. This is different from the first embodiment. Details will be described below.

  The cap sheet 41 constituting the bubble board 4 has a three-dimensional structure including a large number of projections 47 having a circular shape in plan view, and the projections 47 are arranged in a line along the width direction and flow. Staggered along the direction. The size and shape of each protrusion 47 are all set to be the same. The air chambers 45 formed in the protrusions 47 have the same size and shape, and their volumes are also the same.

  The sound-absorbing material body 2 corresponds to the first small holes 22a formed corresponding to the first row of air chambers 45 and the second row of air chambers 45 adjacent to the first row. The second small hole 22b is formed, and the size of the first small hole 22a and the size of the second small hole 22b are different from each other. Specifically, each of the first small holes 22a is formed so as to open at a central portion corresponding to each of the air chambers 45 in the first row in the backsheet 42, in other words, at an intermediate position of the finite space. It is provided and has a circular shape in plan view with a diameter set to about 1.0 mm. On the other hand, each of the second small holes 22b is formed so as to open at a central portion corresponding to each of the air chambers 45 in the second row in the backsheet 42, in other words, at an intermediate position of the finite space. It has a circular shape in plan view with a diameter of about 5.0 mm.

  That is, in the sound-absorbing material 1 according to the present embodiment, among the elements constituting the Helmholtz resonator, the actual length of the opening (that is, the thickness dimension of the back sheet 42 in which the small holes 22a and 22b are formed) and the volume of the air part A plurality of Helmholtz resonators having the same size (that is, the size of the protrusion 47) and different sectional areas of the openings (that is, the opening areas of the small holes 22a and 22b) are provided.

  If it is such, the effect according to 1st Embodiment is acquired. In addition, the frequency absorbed by the first Helmholtz resonator composed mainly of the first small hole 22a and the air chamber 45 behind it, the second small hole 22b and the air chamber 45 behind the second small hole 22b, Therefore, the sound absorbing performance of the entire sound absorbing material 1 can be improved. In other words, for a sound including a plurality of peak frequencies, a plurality of types of frequencies, specifically, frequencies that enter the air chamber 45 from the first small hole 22a and resonate in the air chamber 45. And the frequency that enters the air chamber 45 through the second small hole 22b and resonates in the air chamber 45 can be absorbed, so that the frequency bandwidth in which the sound absorption effect appears is widened and the sound absorption effect is exerted on the peak frequency sound source. Can be improved.

  The method of making the size of the small holes different from each other is not limited to (1) changing the diameter as described above. For example, (2) changing the shape of the small holes (the shape of the small holes is the same as that described above). The shape of the small hole is related to the cross-sectional area of the opening among the elements constituting the Helmholtz resonator), and (3) the backsheet around the small hole. Of course, the actual length of the opening may be changed by changing the thickness dimension, or (1) to (3) may be combined.

  Further, the diameter of the small holes may be plural, or the ratio of the small holes having different diameters may be arbitrarily set. That is, in the above-described second embodiment, two types of small holes, the first small hole and the second small hole, are formed, but three or more types of small holes may be formed. Furthermore, the ratio of each small hole to the entire sound-absorbing material is not limited to the above-described arrangement in which the first small hole is 50%, the second small hole is 50%, and the small holes are arranged in the same ratio. Alternatively, the first small holes may be arranged at different ratios such as 20%, the second small holes may be 80%, and the like.

<Third Embodiment (FIGS. 7 and 8)>
Next, a sound absorbing material 1 according to a third embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

  The sound absorbing material 1 of the present embodiment is provided with small holes 22a and 22b that allow the air chambers 45a and 45b to communicate with the outside in the sound absorbing material body 2 made of the bubble board 4, and seals the end surface 21 of the sound absorbing material body 2. The communication between the non-air chamber 46 on the end surface 21 and the outside is blocked. The sound-absorbing material body 2 includes a plurality of small holes 22a and 22b and air chambers 45a and 45b corresponding to the small holes 22a and 22b, and the volumes of the air chambers 45a and 45b are different from each other. This is different from the first embodiment. Details will be described below.

  The cap sheet 41 constituting the bubble board 4 has a three-dimensional structure including a large number of projections 47a and 47b having a circular shape in plan view, and the projections 47a and 47b are arranged in a line along the width direction. And staggered along the flow direction. The sizes of the protrusions 47a and 47b of the present embodiment are different between the first row and the second row adjacent to the first row. Specifically, the first protrusions 47a arranged in the first row have a height dimension of the protrusion 47a of about 5 mm and a diameter of about 6 mm. On the other hand, the second protrusions 47b arranged in the second row have a height dimension of the protrusion 47b of about 5 mm and a diameter of about 12 mm. The sizes of the air chambers 45a and 45b formed in the protrusions 47a and 47b are different between the first row and the second row, and the volume of the air chamber 45b in the second row is the same. It is set to be larger than the volume of the air chambers 45a in the first row.

  The sound-absorbing material body 2 is made to correspond to the first small holes 22a formed corresponding to the first row of air chambers 45a and the second row of air chambers 45b adjacent to the first row. The second small hole 22b is formed, and the size of the first small hole 22a and the size of the second small hole 22b are set to the same size. Specifically, each of the first small holes 22a is formed so as to open to a central portion corresponding to each of the air chambers 45a in the first row in the backsheet 42, in other words, to open at an intermediate position of the finite space. It is provided and has a circular shape in plan view with a diameter set to about 1.5 mm to 2.0 mm. On the other hand, each of the second small holes 22b is formed so as to open to a central portion corresponding to each of the air chambers 45b in the second row of the backsheet 42, in other words, to open at an intermediate position of the finite space. It has a circular shape in plan view with a diameter set to about 1.5 mm to 2.0 mm.

  That is, in the sound-absorbing material 1 according to the present embodiment, among the elements constituting the Helmholtz resonator, the sectional area of the opening (that is, the opening area of the small holes 22a and 22b) and the actual length of the opening (that is, the small holes 22a, And a plurality of Helmholtz resonators having the same air volume (that is, the size of the projections 47a and 47b).

  If it is such, not only the effect according to the first embodiment can be obtained but also the effect according to the second embodiment can be obtained. That is, the frequency absorbed by the first Helmholtz resonator composed mainly of the first small hole 22a and the air chamber 45a behind the first small hole 22a, and the second small hole 22b and the air chamber 45b behind the second small hole 22b. Since the frequency of sound absorption by the second Helmholtz resonator configured as the main body can be made different, it is possible to widen the frequency bandwidth in which the sound absorption effect appears in the sound absorbing material 1 as a whole.

  In addition, the method of making the volume of the air chambers different from each other is not limited to (1) changing the diameter of the protrusion as described above. For example, (2) changing the shape of the protrusion (the shape of the protrusion is the same as described above). The shape of the protrusion is related to the volume of the air part among the elements constituting the Helmholtz resonator), (3) the height of the protrusion is changed (the height of the protrusion) Of course, these dimensions (1) to (3) may be combined with each other in relation to the volume of the air portion among the elements constituting the Helmholtz resonator.

  Further, the diameter of the protrusion may be plural, or the ratio of the protrusions having different diameters may be arbitrarily set. That is, in the above-described third embodiment, two types of air chambers, the first row of air chambers and the second row of air chambers, are formed, but three or more types of air chambers may be formed. . Further, the ratio of each air chamber to the entire sound absorbing material is 50% for the first row of air chambers and 50% for the second row of air chambers as described above, and the air chambers are arranged in the same ratio. For example, the air chambers in the first row may be arranged at different ratios such as 20%, the air chambers in the second row, 80%, and the like.

  Further, by combining the method of differentiating the volume of the air chamber of the present embodiment with the method of differentiating the size of the small holes of the second embodiment described above, a single sound absorbing material can be obtained. Of course, a plurality of different resonance frequencies may be present to widen the frequency bandwidth having a sound absorbing effect.

<Fourth Embodiment (FIGS. 9 and 10)>
Next, a sound absorbing material 1 according to a fourth embodiment of the present invention will be described with reference to FIGS. 9 and 10. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

  The sound absorbing material 1 of the present embodiment is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and the end surface 21 of the sound absorbing material main body 2 is sealed to Communication between the non-air chamber 46 on the end face 21 and the outside is blocked. The sound absorbing material main body 2 is different from the first embodiment in that a small hole 23 that allows the non-air chamber 46 to communicate with the outside is provided in the back sheet 42. Details will be described below.

  The sound absorbing material body 2 includes a first small hole 22 formed corresponding to each air chamber 45 and a second small hole 23 formed corresponding to the non-air chamber 46. The size of the first small hole 22 and the size of the second small hole 23 are set to the same size. Specifically, each of the first small holes 22 is formed so as to open at a central portion corresponding to each air chamber 45 in the back sheet 42, in other words, at an intermediate position of the finite space. , And has a circular shape in plan view with a diameter set to about 1.5 mm to 2.0 mm. On the other hand, each of the second small holes 22 is a portion where the air bubbles 44 are not formed in the back sheet 42, in other words, a portion where the projection 47 of the cap sheet 41 is not formed and the back sheet 42 is in close contact. It is formed. Specifically, each of the second small holes 23 is formed so as to open between the adjacent first small holes 22 and has a diameter set to about 1.5 mm to 2.0 mm in plan view. It has a circular shape.

  If it is such, the effect according to 1st Embodiment is acquired. In addition, the first Helmholtz resonator mainly composed of the first small hole 22 and the air chamber 45 behind the first small hole 22 can absorb sound of a predetermined frequency, and the second small hole 23 and the back thereof. Since the second Helmholtz resonator composed mainly of the non-air chamber 46 can absorb sound different from the predetermined frequency, sound absorption performance is improved. More specifically, in this embodiment, the end surface 21 of the sound-absorbing material main body 2 is sealed to block communication between the non-air chamber 46 on the end surface 21 and the outside. It is a finite space with a larger volume than Therefore, a huge Helmholtz resonator can be formed by the non-air chamber 46 and the second small hole 23.

  That is, the sound-absorbing material 1 according to the present embodiment includes a plurality of Helmholtz resonators having different cross-sectional areas of the openings, actual lengths of the openings, and volumes of the air portions among the elements constituting the Helmholtz resonator. ing. Specifically, the first Helmholtz resonator has a single small hole 22 for each air chamber 45, while the second Helmholtz resonator has a large number of small holes for the non-air chamber 46. 23, and the sectional area of the opening of the first Helmholtz resonator is set smaller than the sectional area of the opening of the second Helmholtz resonator. In the first Helmholtz resonator, the small holes 22 are formed in the thickness dimension of the back sheet 42 alone, while the second Helmholtz resonator has the small holes in the total thickness dimension of the back sheet 42 and the cap sheet 41. 23 is formed, and the actual length of the opening of the first Helmholtz resonator is set smaller than the actual length of the opening of the second Helmholtz resonator. Furthermore, in the first Helmholtz resonator, the volume of the air part depends on the size of each air chamber 45, whereas in the second Helmholtz resonator, the volume of the air part depends on the size of the entire non-air chamber 46. The volume of the air part of the first Helmholtz resonator is set smaller than the volume of the air part of the second Helmholtz resonator.

  The small holes that allow the non-air chamber to communicate with the outside may be provided on the liner sheet side, and the number of small holes, the size, shape, and arrangement of the small holes are not limited to those illustrated. However, various changes can be made.

<Fifth Embodiment (FIG. 11)>
Next, a sound absorbing material 1 according to a fifth embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

  The sound absorbing material 1 of the present embodiment is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and the end surface 21 of the sound absorbing material main body 2 is sealed to Communication between the non-air chamber 46 on the end face 21 and the outside is blocked. And the point from which the said sound-absorbing-material main body 2 is provided with the outer-layer sheet | seat 5 on the surface of the back seat | sheet 42 differs from 1st Embodiment.

  The outer layer sheet 5 is, for example, a non-woven fabric having a sound absorbing effect, and is laminated by heat welding to the outer surface side of the back sheet 42 without closing the small holes 22 formed in the back sheet 42. The small holes 22 formed in the back sheet 42 are set to dimensions that are not closed by the heat of heat welding when the outer layer sheet 5 is heat welded.

  If it is such, the effect according to the sound-absorbing material 1 of 1st Embodiment mentioned above is acquired. Moreover, according to the sound absorbing material 1 of this embodiment, the outer layer sheet 5 can protect the dust and dirt from adhering directly to the small holes 22. Further, by covering the small holes 22 with a non-woven fabric so that the small holes 22 are not visible, the interior decoration can be achieved.

  The outer layer sheet laminated on the outer surface of the sound-absorbing material body is not limited to a non-woven fabric and can be variously changed.However, the outer-layer sheet may be a non-woven fabric or other porous material having a sound absorbing effect as in this embodiment. For example, noise in a predetermined frequency band can be absorbed by the outer layer sheet, and noise in other frequency bands can be absorbed using an air chamber that opens through a small hole. Therefore, a sound-absorbing material having high sound-absorbing performance over the entire audible range can be obtained without canceling the effects of the sound-absorbing material body and the outer layer sheet.

  Further, the outer layer sheet may be attached to the liner sheet side, or may be attached to both the back sheet side and the liner sheet side, in addition to those attached to the back sheet side. Furthermore, the outer layer sheet may cover not only the entire sound absorbing material body, but also cover only a part of the sound absorbing material, or a plurality of types of outer layer sheets may be laminated on the outer surface of the sound absorbing material body. .

< First Reference Example (FIG. 12)>
Next, the sound-absorbing material 1 according to the first reference example that exhibits an effect similar to that of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

The sound absorbing material 1 of the present reference example is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and the end surface 21 of the sound absorbing material main body 2 is sealed. Communication between the non-air chamber 46 on the end face 21 and the outside is blocked. And the method of sealing the end surface 21 of the said sound-absorbing material main body 2 differs from 1st Embodiment. Details will be described below.

The sealing member 3 of the present reference example covers the end surface 21 (side surface) of the sound absorbing material main body 2 and is arranged so as to close all the end edge surfaces 21 of the sound absorbing material main body 2. The sealing member 3 is formed integrally with the back sheet 42, and the end of the sealing member 3 and the end of the liner sheet 43 are joined in a substantially orthogonal state. The joining between the sealing member 3 and the liner sheet 43 and the joining between the sealing member 3 and the edge of the small edge of the cap sheet 41 are performed by thermal welding. Of course, these bondings may be performed by bonding using an adhesive or the like.

If it is such, the effect according to the sound-absorbing material 1 of 1st Embodiment mentioned above is acquired. Moreover, according to the sound absorbing material 1 of the present reference example , the end of the back sheet 42 can be extended and used as the sealing member 3. The score can be reduced. Therefore, the number of man-hours required for parts management and manufacturing can be reduced without difficulty. In addition, the length dimension of the sealing member may be set larger than the thickness dimension of the cap sheet so that the end of the sealing member reaches a part of the outer surface of the liner sheet.

< Second Reference Example (FIG. 13)>
Next, a sound absorbing material 1 according to a second reference example that exhibits an effect similar to that of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

The sound absorbing material 1 of the present reference example is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and the end surface 21 of the sound absorbing material main body 2 is sealed. Communication between the non-air chamber 46 on the end face 21 and the outside is blocked. And the method of sealing the end surface 21 of the said sound-absorbing material main body 2 differs from 1st Embodiment. Details will be described below.

The sealing member 3 of the present reference example covers the end surface 21 (side surface) of the sound absorbing material main body 2 and is arranged so as to close all the end edge surfaces 21 of the sound absorbing material main body 2. The sealing member 3 is formed integrally with the liner sheet 43, and the end of the sealing member 3 and the end of the back sheet 42 are joined in a substantially orthogonal state. The joining between the sealing member 3 and the back sheet 42 and the joining between the sealing member 3 and the edge of the small edge of the cap sheet 41 are performed by thermal welding. Of course, these bondings may be performed by bonding using an adhesive or the like.

If it is such, the effect according to the sound-absorbing material 1 of 1st Embodiment mentioned above is acquired. In addition, according to the sound absorbing material 1 of the present reference example , the end of the liner sheet 43 can be extended and used as the sealing member 3. The score can be reduced. Therefore, the number of man-hours required for parts management and manufacturing can be reduced without difficulty. Furthermore, compared to the first reference example , the sealing member 3 has a smooth curved surface and is joined to the back sheet 42, so that the corners are removed, and safety requirements and appearance are improved. Can respond appropriately to requests. As in the first reference example , the length of the sealing member is set larger than the thickness of the cap sheet so that the end of the sealing member reaches a part of the outer surface of the back sheet. It may be the one.

< Third Reference Example (FIG. 14)>
Next, a sound-absorbing material 1 according to a third reference example that exhibits an effect similar to that of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 1st Embodiment, or respond | corresponds to this, and detailed description is abbreviate | omitted.

The sound absorbing material 1 of the present reference example is provided with a small hole 22 that allows the air chamber 45 to communicate with the outside in the sound absorbing material main body 2 made of the bubble board 4, and the end surface 21 of the sound absorbing material main body 2 is sealed. Communication between the non-air chamber 46 on the end face 21 and the outside is blocked. And the method of sealing the end surface 21 of the said sound-absorbing material main body 2 differs from 1st Embodiment. Details will be described below.

The sealing member 3 of the present reference example covers the end surface 21 (side surface) of the sound absorbing material main body 2 and is arranged so as to close all the end edge surfaces 21 of the sound absorbing material main body 2. The sealing member 3 is formed integrally with the back sheet 42 and the liner sheet 43, and an end portion of the sealing member 3 extending from the back sheet 42 side and the liner sheet at an intermediate portion of the sealing member 3. The end of the sealing member 3 extending from the 43 side is joined. Bonding between the end of the sealing member 3 extending from the back sheet 42 side and the end of the sealing member 3 extending from the liner sheet 43 side, and bonding between the sealing member 3 and the edge edge of the cap sheet 41 are as follows: This is done by heat welding. Specifically, a pair of heat seal bars (not shown) are moved in the direction of approaching so that the corners thereof are along the virtual sealing end face, and the back sheet 42 and the liner sheet 43 are heated in the direction in which they are in close contact with each other. Press. Thereafter, the back sheet 42 and the liner sheet 43 are cut by a heat seal bar to seal the end face 21, and a portion curved by the pressing of the back sheet 42 and the liner sheet 43 is used as the sealing member 3.

If it is such, the effect according to the sound-absorbing material 1 of 1st Embodiment mentioned above is acquired. Moreover, according to the sound absorbing material 1 of the present reference example , the ends of the back sheet 42 and the liner sheet 43 can be extended and used as the sealing member 3, so that the special sealing member 3 is used. Compared to this, the number of parts can be reduced. Therefore, the number of man-hours required for parts management and manufacturing can be reduced without difficulty. Furthermore, the sealing member 3 has a smooth curved surface as compared with the first reference example , and can appropriately respond to safety requirements and appearance requirements.

The material, shape, and the like of the sealing member are not limited to those illustrated, and can be variously changed.

  The present invention is not limited to the embodiment described above.

  For example, the small holes need not be disposed in all the air chambers. Moreover, the arrangement | positioning method of each small hole may be regular, and may be irregular. Further, the number of small holes formed, the total area where the small holes are formed, and the size and / or shape of each small hole can be variously changed as long as the strength of the sound absorbing material is not lowered. That is, the natural frequency can be changed and the degree of freedom of design can be increased by variously changing the size of the small holes, the opening ratio, and the like.

  The shape of the air chamber may be a semicircular shape, a rectangular parallelepiped shape, a so-called honeycomb shape, a cone shape (conical shape), or the like in addition to the illustrated cylindrical shape.

  Furthermore, the material of the bubble board is not limited to that made of synthetic resin, and may be made of fiber (for example, wood or paper) or metal that can be easily press-molded.

  Further, the shape of the sound absorbing material is not limited to a rectangular shape in plan view, and can be variously changed.

  Furthermore, the sound-absorbing material main body may be provided with a small hole in the liner sheet that allows the air chamber to communicate with the outside. In addition, when providing a small hole in the liner sheet, it is necessary to form a hole that penetrates both the liner sheet and the top surface of the protrusion of the cap sheet, but this part melts the liner sheet and the cap sheet. Because of the close contact, it is difficult to accurately grasp the actual length of the opening (that is, the total thickness dimension of the back sheet and the cap sheet in which small holes are formed). However, when a small hole is provided on the backsheet side as in the above-described embodiment, the backsheet set to a certain thickness is used, so that the actual length of the opening can be grasped in advance. Therefore, it is possible to easily form a sound absorbing material that can handle a desired frequency.

  Further, in addition to the sound absorbing effect of the Helmholtz resonator described above, small holes may be provided on both the back sheet side and the liner sheet side for the purpose of guiding the sound source to the opposite side of the sound absorbing material. In this case, the sound absorbing material can be enclosed by a member for holding the sound absorbing material, a structural housing or a wall disposed behind the sound absorbing material, and a finite space can be configured to absorb the sound.

  In addition, various changes may be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Sound absorption material 2 ... Sound absorption material main body 21 ... End surface 22, 22a, 22b, 23 ... Small hole 4 ... Bubble board 41 ... Cap sheet 42 ... Back sheet 43 ... Liner sheet 44, 44a, 44b ... Bubble 45, 45a, 45b ... Air chamber 46, 46a, 46b ... Non-air chamber 47, 47a, 47b ... Projection

Claims (6)

A cap sheet having a plurality of protrusions for forming bubbles, a back sheet that is attached to the open side of the protrusions of the cap sheet and forms a plurality of bubbles corresponding to the protrusions, and tips of the protrusions of the cap sheet A liner sheet attached to the side, and an air chamber formed in each projection between the back sheet and the liner sheet, and a non-air chamber formed outside each projection. A sound-absorbing material made of a bubble board provided,
The sound absorbing material body made of the bubble board is provided with a small hole for communicating the air chamber to the outside, and the end surface of the sound absorbing material body is separate from the sound absorbing material body and protrudes through the protrusion of the cap sheet A sound absorbing material, characterized in that it is sealed by a sealing member provided to prevent the sound propagated outside from leaking to the outside, and communication between the non-air chamber at the end surface and the outside is blocked . The sound-absorbing material according to claim 1, wherein the sound-absorbing material main body includes a plurality of small holes and air chambers corresponding to the small holes, and the sizes of the small holes are different from each other. The sound-absorbing material according to claim 1 or 2, wherein the sound-absorbing material main body includes a plurality of small holes and air chambers corresponding to the small holes, and the volumes of the air chambers are different from each other. The sound-absorbing material according to claim 1, 2, or 3, wherein the sound-absorbing material body is provided with a small hole in the back sheet and / or liner sheet for communicating the non-air chamber to the outside. The sound-absorbing material according to claim 1, 2, 3, or 4, wherein the sound-absorbing material body is a back sheet provided with the small holes. The sound-absorbing material body includes a plurality of small holes provided in a back sheet and air chambers corresponding to the small holes, and the periphery of the small holes is an opening that allows the air chamber to communicate with the outside. The sound-absorbing material according to claim 1, 2, 3, 4 or 5, wherein the thickness of the back sheet is varied to change the actual length of the opening.

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