JP2021096304A - Soundproof structure - Google Patents

Abstract

To provide a soundproof material which exhibits high soundproof performance over a wide range of frequencies 2000 Hz or lower and capable of demonstrating sufficient soundproof performance even when applied to a substrate having curved faces, and, furthermore, suppresses a decrease in strength against external forces.SOLUTION: A soundproof material 10 is constituted from an elastic sheet 110 and a plurality of lattice-shaped structures 100 for holding the sheet 110 and having a hollow cell that divides the sheet 110 into a plurality of sections. The soundproof material 10 is arranged on a substrate having curved faces such that the sheet 110 is arranged on a substrate 20 side relative to the lattice-shaped structures 100 and a normal h of the sections divided by each of the hollow cells is approximately perpendicular to the substrate, whereby the soundproof structure 1 is constituted.SELECTED DRAWING: Figure 1

Description

The present invention relates to a soundproof structure.

There are many sound sources in the car. Since quietness from noise inside and outside the vehicle is required, various soundproofing measures are taken for automobiles. In particular, for parts that generate loud noise (unique sound sources) such as engines, transmissions, and drive trains, soundproofing measures are required at positions close to the source. For this reason, a dedicated soundproof cover having excellent sound absorption and insulation performance is used for these sound sources. Here, the demand for noise-reducing parts in automobiles is extremely high, due to the fact that the regulations on the noise level outside the vehicle are strengthened due to successive revisions of the law and that the noise reduction inside the vehicle is directly linked to the value (luxury) of the vehicle. .. In particular, the external noise regulation introduced in the European Union (EU) in 2013 is finally stricter than the conventional regulation value of -3dB (reduction of sound pressure energy by 1/2). .. For this purpose, it is indispensable to take noise reduction measures for the engine body and the inherent sound source such as the transmission as the main noise source in the engine room. Various soundproofing parts such as the engine top cover on the upper surface side of the engine have been used so far, but further improvement in performance is required. Further, from the viewpoint of fuel efficiency, it is preferable that the soundproofing measures can meet the demand for weight reduction.

There are various known configurations of soundproof structures aimed at soundproofing, but among them, there is a material called "acoustic metamaterial". An "acoustic metamaterial" is an artificial medium designed to exhibit acoustic properties that naturally occurring substances do not normally exhibit. Conventionally, acoustic metamaterials exhibiting a desired soundproofing effect have been enthusiastically developed, and various proposals have been made.

Here, when a sound wave having a frequency on a single wall made of a homogeneous material is vertically incident, the value of transmission loss (TL) due to the single wall is the frequency (f) and the surface density of the single wall. It is known that TL ≈ 20 log ₁₀ (m · f) −43 [dB] is calculated using (m) (mass rule). That is, in general, the lighter the soundproofing material and the lower the frequency of the sound wave, the smaller the transmission loss (TL) and the lower the soundproofing performance. For example, in the case of a sound wave of 500 Hz, in order to achieve an STL of 20 dB, a size of 12 cm is required for a concrete wall and a size of more than 35 cm is required for a urethane foam sound insulating material.

In view of such a situation, for example, in Non-Patent Document 1, a lattice-like structure in which a latex rubber film is airtightly supported by a honeycomb made of an aramid fiber sheet having a plurality of continuously formed tubular cells. Acoustic metamaterials have been proposed. Here, in the lattice-like structure disclosed in Non-Patent Document 1, the latex rubber film is formed into a compartment having a regular hexagonal shape (one side length is 3.65 mm) by a plurality of tubular cells. It is partitioned.

According to Non-Patent Document 1, it is said that by using such an acoustic metamaterial, it is possible to provide a material that is lightweight but has excellent soundproofing performance particularly against low frequency sound waves. Is also disclosed to be able to achieve STL greater than 25 dB.

Ni Sui et al., Applied Physics Letters 106, 171905 (2015)

However, when the above acoustic metamaterial as described in Non-Patent Document 1 is used as a soundproofing material, it may not be possible to exhibit sufficient soundproofing performance over a wide frequency range of 2000 Hz or less. Was found by the examination of the present inventors.

Further, when the soundproofing material (acoustic metamaterial) as described above is applied to a vehicle or the like, it is generally laminated with a substrate for arranging the soundproofing material. However, according to the study by the present inventors, when the substrate to which the soundproofing material is applied has a curved surface, even if the acoustic metamaterial is used as the soundproofing material and applied as it is to the curved surface of the substrate, the present invention is concerned. It was also found that the soundproofing material could not follow the curved surface and sufficient soundproofing performance could not be obtained. In this case, if the soundproofing material is forcibly curved to follow the curved surface of the substrate, stress is generated inside the soundproofing material, which in turn causes deformation of the constituent members of the soundproofing material. As a result, it is not possible to obtain the soundproofing performance as originally designed, and there is a problem that the strength of the soundproofing material against an external force is also lowered.

Therefore, the present invention can exhibit high soundproofing performance over a wide range of a frequency range of 2000 Hz or less, can exhibit sufficient soundproofing performance even when applied to a substrate having a curved surface, and can reduce the strength against external force. The purpose is to provide a means capable of suppressing.

The present inventors have studied for the purpose of providing a means capable of exhibiting high soundproofing performance over a wide range of a frequency range of 2000 Hz or less. As a result, as disclosed in Non-Patent Document 1, soundproofing having an elastic sheet and a support portion composed of a plurality of hollow cells for partitioning the sheet into a plurality of compartments and supporting the sheet. In a material (acoustic metamaterial), the surface rigidity and surface density of the sheets constituting the section are controlled to satisfy a predetermined relationship, so that the material (acoustic metamaterial) is high over a wide frequency range of 2000 Hz or less (particularly 400 to 1000 Hz). We have found that soundproofing performance can be demonstrated.

Further, when the soundproofing material is arranged on the substrate, the normal line of the division portion is arranged so that the sheet is arranged on the substrate side with respect to the support portion and is partitioned by each of the hollow cells. We have found that the above problems that occur when a soundproofing material is applied to a substrate having a curved surface can be solved by arranging the substrates so as to be substantially perpendicular to the substrate, and have completed the present invention.

That is, according to one embodiment of the present invention, there is provided a soundproof structure having a substrate having a curved surface and a soundproof material arranged on the substrate. Here, the soundproofing material includes an elastic sheet and a support portion that is composed of a plurality of hollow cells that partition the sheet into a plurality of compartments and supports the sheet. The soundproofing material is characterized in that the surface rigidity (k) and surface density (m) of the sheet in the compartment satisfy the relationship of the following formula 1.

Further, in the soundproof structure, the sheet is arranged on the substrate side with respect to the support portion, and the normal of the partition portion partitioned by each of the hollow cells is relative to the substrate. Another feature is that the soundproofing material is arranged on the substrate so as to be substantially vertical.

According to the soundproof structure according to the present invention, high soundproof performance can be exhibited over a wide range of a frequency range of 2000 Hz or less, and sufficient soundproof performance can be exhibited even when applied to a substrate having a curved surface. Moreover, it is possible to suppress a decrease in strength against an external force.

It is a side view which shows the appearance of the soundproof structure which concerns on one Embodiment of this invention. It is a perspective view which shows the appearance of the soundproof material which constitutes the soundproof structure which concerns on one Embodiment of this invention. It is a top view of the soundproof material which constitutes the soundproof structure which concerns on one Embodiment of this invention. It is a graph for demonstrating the soundproofing performance (transmission loss @ 500Hz) of the soundproofing material which concerns on this invention in comparison with the performance trend in the conventionally known soundproofing material. It is a graph for demonstrating the change of the soundproofing performance (transmission loss) according to the mass rule when the surface density of a soundproofing material is increased. The soundproofing performance (transmission loss) of the soundproofing material according to the present invention is compared with the soundproofing material consisting only of a lattice-like structure (support portion) having a honeycomb structure, the soundproofing material consisting of only a single wall, and the soundproofing material made of an iron plate. It is a graph for explaining. It is a figure for demonstrating the soundproofing performance according to the rigidity law. A graph showing a model formula assuming that both the mass law (FIG. 5) and the rigidity law (FIG. 7) are involved in the soundproofing performance of the soundproofing material according to the present invention, in comparison with the measured values of transmission loss. Is. It is a perspective view which shows the appearance of the soundproof material which constitutes the soundproof structure which concerns on other embodiment of this invention. It is a side view which shows the appearance of the soundproof structure which concerns on other embodiment of this invention. It is a top view which shows the modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a top view which shows the other modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a top view which shows the further modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a top view which shows the further modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a perspective view which shows the appearance of the soundproof material which constitutes the soundproof structure which concerns on still another Embodiment of this invention. It is a top view which shows the further modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a top view which shows the further modification of the soundproof material which constitutes the soundproof structure which concerns on this invention. It is a photograph for demonstrating the state of the measurement system (sound insulation box) used for evaluating the soundproofing performance in the column of Examples described later. It is a photograph which evaluated the soundproofing performance of the soundproofing material produced in the comparative example described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in the comparative example described later. It is a photograph of a state in which the soundproofing performance of the soundproofing material produced in Example 1 described later was evaluated. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 1 which will be described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 2 described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 3 described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 4 described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 5 described later. It is a graph which shows the result of having measured the insertion loss about the soundproofing material produced in Example 6 which will be described later.

One embodiment of the present invention comprises a substrate having a curved surface; an elastic sheet, and a support portion composed of a plurality of hollow cells for partitioning the sheet into a plurality of compartments and supporting the sheet. The surface rigidity (k) of the sheet and the surface density (m) of the sheet in the section satisfy the relationship of the following formula 1 and have a soundproofing material arranged on the substrate; the sheet is the support portion. The soundproofing material is placed on the substrate so as to be arranged on the substrate side with respect to the substrate and so that the normal of the compartmentalized portion partitioned by each of the hollow cells is substantially perpendicular to the substrate. It is a soundproof structure that is arranged.

The method of calculating the surface rigidity (k) and the surface density (m) in Equation 1 will be described later.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios. In the present specification, "X to Y" indicating a range means "X or more and Y or less". Unless otherwise specified, operations and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50%.

FIG. 1 is a side view showing the appearance of the soundproof structure according to the embodiment of the present invention. FIG. 2 is a perspective view showing the appearance of the soundproofing material constituting the soundproofing structure according to the embodiment of the present invention. FIG. 3 is a top view of a soundproof material constituting the soundproof structure according to the embodiment of the present invention.

As shown in FIG. 1, the soundproof structure 1 according to the embodiment of the present invention is soundproof in which the surface rigidity (k) of the sheet and the surface density (m) of the sheet in the compartment satisfy the relationship of the above-mentioned formula 1. It has a material 10 and a substrate 20. As shown in FIGS. 1 to 3, the soundproofing material 10 according to the embodiment of the present invention has a plurality of lattice-like structures 100 (consisting of a plurality of hollow cells 100a arranged continuously (regularly)). A support portion) and a latex rubber sheet 110 made of elastic latex rubber are provided. Here, the plurality of lattice-like structures 100 are arranged on the latex rubber sheet 110 so as to exist independently of each other (that is, in a state of being configured as a separate body from other lattice-like structures). .. The latex rubber sheet 110 is airtightly bonded to the grid-like structure 100 so as to close one side of the openings on both sides of the grid-like structure 100, and functions as a sheet-like base material. The thickness of the latex rubber sheet 110 in this embodiment is 0.25 mm (250 μm). On the other hand, in the present embodiment, the lattice structure 100 is made of polypropylene (PP) resin.

Further, as shown in FIG. 1, in the soundproof structure 1 according to the present embodiment, the substrate 20 has a curved surface. The soundproofing material 10 is arranged on the substrate 20 so that the latex rubber sheet 110 constituting the soundproofing material 10 is arranged on the substrate 20 side with respect to the lattice structure 100. At this time, since the latex rubber sheet 110 is flexible, it is deformed so as to follow the curved surface of the substrate 20. As a result, as shown in FIG. 1, each grid-like structure 100 determines its relative arrangement so as to correspond to the deformation of the latex rubber sheet 110 to which it is joined. That is, the soundproofing material 10 is provided so that the normal line (for example, the virtual line h shown in FIG. 1) of the section defined by each of the hollow cells 100a of the lattice structure 100 is perpendicular to the substrate 20. It is arranged on the substrate 20. In other words, the soundproofing material 10 is arranged on the substrate 20 so that the latex rubber sheet 110 corresponding to the compartments partitioned by each of the hollow cells 100a of the lattice structure 100 is parallel to the substrate 20. .. Here, in the present specification, "the soundproofing material is arranged on the substrate" does not mean only that the soundproofing material is arranged vertically above the substrate. As long as the soundproofing material and the substrate are arranged so that the sheet constituting the soundproofing material is arranged on the substrate side with respect to the support portion, the soundproofing material can be arranged in any direction with respect to the substrate. For example, the soundproofing material 10 may be arranged vertically below the substrate 20.

In this way, the soundproofing material 10 is arranged on the substrate 20 so that the normal of the compartments partitioned by each of the hollow cells 100a of the lattice structure 100 is perpendicular to the substrate 20, 2000 Hz. High soundproofing performance can be exhibited over a wide range of the following frequency range, sufficient soundproofing performance can be exhibited even when applied to a substrate having a curved surface, and a decrease in strength against external force can be suppressed. It becomes. Further, when the soundproofing material cannot follow the substrate having a curved surface, a dead space is generated in the space above the substrate. On the other hand, according to the soundproof structure according to the present embodiment, as a result of the soundproof material being able to follow the curved surface of the substrate, it is possible to prevent the occurrence of such a dead space, which also contributes to the improvement of space efficiency. can do.

As described above, in the soundproof structure of the form shown in FIG. 1, the soundproofing is performed so that the normal of the section defined by each of the hollow cells of the lattice structure is perpendicular to the substrate. The material is arranged on the substrate. However, in the present invention, the angle between the normal line and the substrate is not limited to vertical (90 °), and may be "substantially vertical". "Approximately vertical" means that the deviation of the normal from the vertical is within 15 °, preferably within 12 °, more preferably within 10 °, and even more preferably within 7 °. , Even more preferably within 5 °, even more preferably within 2 °, particularly preferably within 1 °, and most preferably within 0 ° (vertical).

Further, as shown in FIGS. 2 and 3, in the soundproofing material 10 according to the present embodiment, the hollow cell in the cross section (paper surface of FIG. 3) perpendicular to the extending direction of the hollow cell 100a constituting the lattice structure 100. The cross-sectional shape of 100a is rectangular. As a result, the lattice structure 100 according to the present embodiment supports the latex rubber sheet 110 as a sheet-like base material, and the latex rubber sheet 110 is divided into a plurality of (many in FIGS. 2 and 3) compartments. It is partitioned. The plurality of compartments form a regular array structure in which the plurality of compartments having the same outer shape are regularly arranged.

As described above, the soundproofing material having the configurations shown in FIGS. 2 and 3 can realize excellent soundproofing performance with a very simple configuration. In particular, despite its lightweight and simple configuration, it is possible to exhibit characteristics that cannot be achieved by conventional techniques, such as being able to exhibit high soundproofing performance over a wide range of frequencies of 2000 Hz or less.

The present inventors have energetically studied the mechanism by which the soundproofing material as in the above-described embodiment exhibits such excellent soundproofing performance. As a result, it was found that a mechanism different from the soundproofing material conventionally applied to vehicles and the like is involved, and the present invention has been completed. The mechanism finally found has overturned the conventional wisdom regarding soundproofing materials applied to vehicles and the like. Hereinafter, the mechanism by which the soundproofing material according to the present embodiment exhibits excellent soundproofing performance and the configuration of the present invention completed based on the mechanism elucidated by the present inventors will be described step by step.

First, FIG. 4 shows the soundproofing performance (@ 500Hz) of the soundproofing material according to the present invention in comparison with the performance trend of the conventionally known soundproofing material. As shown in FIG. 4, in conventionally known soundproofing materials, there has been a performance trend that the soundproofing performance (transmission loss) improves as the density of the constituent materials increases. The performance trend in such conventionally known soundproofing materials is known as the "mass law". The theoretical value (TL) of transmission loss in a soundproofing material according to this mass law is calculated according to the following formula 2 using the frequency (f) of the sound wave of interest and the surface density (m; mass per unit area) of the soundproofing material. Will be done.

Therefore, if the surface density of the soundproofing material is increased, the soundproofing performance (transmission loss (TL)) can be improved, but on the other hand, in order to improve the soundproofing performance, the surface density of the soundproofing material must be increased. That was the common wisdom in the prior art based on the mass law (Fig. 5). In other words, it was believed that it was impossible to construct a soundproofing material that exhibits high soundproofing performance over a wide range of frequencies below 2000 Hz from a lightweight material. On the other hand, the soundproofing material according to the present invention exhibits excellent soundproofing performance so as to deviate significantly from this performance trend (that is, exhibits relatively high soundproofing performance even at low density (lightweight)) (Fig.). 6).

More specifically, as shown in FIG. 6, the soundproofing performance is not exhibited at all only by the lattice-shaped structure (support portion) having the honeycomb structure. In addition, in the case of a soundproofing material consisting of a single wall, the soundproofing performance according to the mass law (the transmission loss increases in the high frequency range but decreases in the low frequency range) with only the elastic sheet (rubber film). It will only be demonstrated. Therefore, in order to exhibit the soundproofing performance in the low frequency region (particularly in the region of 2000 Hz or less), it is necessary to use a material having a very large surface density (that is, heavy) such as an iron plate. On the other hand, the soundproofing material according to the present invention having the above-described configuration exhibits soundproofing performance in accordance with the mass law in the high frequency range, and the value of transmission loss decreases as the frequency decreases. On the other hand, although the soundproofing material according to the present invention is lightweight, it can exhibit excellent soundproofing performance even in a low frequency region (particularly in a region of 2000 Hz or less) with a certain frequency (resonance frequency) as a boundary.

Such a significant improvement in soundproofing performance in the low frequency range cannot be explained by the mass law. Therefore, the present inventors have diligently studied various patterns as a model for explaining such a phenomenon that cannot be explained by the conventional technique. In the process, the present inventors surprisingly discovered that the soundproofing performance in the low frequency range is exhibited according to the "rigidity law", which is a sound insulation principle different from the mass law. This point will be described below.

The theoretical value (TL) of transmission loss in a soundproofing material according to the rigidity law is the frequency (f) of the target sound source, the surface density (m; mass per unit area) of the soundproofing material, and the surface rigidity (K) of the soundproofing material. It is calculated according to the following equation 3. The surface rigidity (K) is similar to a mass spring model in which one of the compartments of the sheet partitioned by the support portion (lattice-like structure) has a mass m and vibrates in response to the incident of sound waves. It is the spring constant at the time of this, and the larger K is, the more difficult it is to deform with respect to the input.

Then, when this equation is solved for the frequency (f) under the condition that the TL takes a minimum value, the value of the resonance frequency (f ₀ ) is expressed by the following mathematical formula 4 (FIG. 7).

Based on this, the present inventors attempted to create a model formula assuming that both the mass law (FIG. 5) and the stiffness law (FIG. 7) are involved in the development of soundproofing performance. Then, it was confirmed that this model formula was consistent with the result of the transmission loss (TL) actually measured, and both the mass law and the rigidity law were involved in the mechanism for exerting the soundproofing performance by the soundproofing material according to this embodiment. We have come to verify that this is the case (Fig. 8).

Although it is not completely clear why not only the mass law but also the rigidity law is involved in the mechanism for exerting the soundproofing performance by the soundproofing material according to this embodiment, the sections of the elastic sheet are each divided. It is considered that the rigidity of the sheet is improved (that is, it is less likely to vibrate) because it is partitioned by the support portion (a lattice-like structure having a tubular cell). Therefore, the present inventors speculate that the mechanism may be well explained by the above-mentioned approximation by the mass spring model.

On the premise of the above mechanism, the present inventors further studied the elements necessary for designing the soundproofing characteristics of the soundproofing material. In the process, the present inventors approximate each section of the elastic sheet with a disk having a radius a having the same area, and the surface rigidity (k; In this specification, the value of the surface stiffness when following this approximation is represented by a lower k), using _{the average deflection (wave) when the disk vibrates in the peripheral fixed / evenly distributed load mode.} The calculation was performed as shown in Equation 5 below. In this specification, the value of k is used in Equation 1.

In Equation 5, ν is the Poisson's ratio of the sheet in the compartment, E is the Young's modulus [Pa] of the sheet in the compartment, and h is the film thickness [m] of the sheet in the compartment. Further, the radius a when the partition portion is approximated to a disk is the area equivalent circular radius [m] of the partition portion. As an example, when the partition portion is a hexagon having a side length of l (L), the area _Shex of the partition portion (hexagon) is calculated by the following mathematical formula 6.

_{Then, the equivalent circle radius aeq} (radius of a circle having an area equal to the area of the section (hexagon)) of this section (hexagon) is calculated by the following mathematical formula 7.

As another example, when the shape of the section is rectangular and the lengths of the sides of the rectangle are p and q, the area _Srec of the section (rectangle) is calculated by the following mathematical formula 8. Will be done.

_{Then, the equivalent salt radius aeq} (radius of a circle having an area equal to the area of the section (rectangle)) of this section (rectangle) is calculated by the following mathematical formula 9.

Then, when the value of the surface rigidity (k) calculated in this way is adopted as the value of the surface rigidity (K) in the above-mentioned equation 4, the value of the resonance frequency (f ₀ ) is as shown in the following equation 10. Can be represented.

The surface density (m) of the sheet in the section can be expressed by the following mathematical formula 11.

In Equation 3, ρ is the density of the sheet in the compartment [kg / m ³ ], and h is the film thickness [m] of the sheet in the compartment.

Therefore, from Equation 10 and Equation 11, _{the value of the resonance frequency (f 0} ) is the value of the sheet density (ρ; mass per unit volume; kg / m ³ ) in the compartment and the above-mentioned compartment. Using the value of the sheet film thickness [m], it can be expressed as in the following mathematical formula 12. This means that the value of the _{resonance frequency (f 0} ) indicated by the soundproofing material can be controlled by variously changing the size and shape of the compartment, the material and the film thickness of the sheet in the compartment.

As described above, the problem to be solved by the present invention is to provide a soundproofing material capable of exhibiting high soundproofing performance over a wide range of a frequency range of 2000 Hz or less. Then, as shown in FIGS. 7 and 8, the soundproofing performance (value of transmission loss) according to the rigidity law becomes more excellent as the frequency becomes smaller with _{the resonance frequency (f 0) as a boundary.} Therefore, the present inventors have considered that the soundproofing performance for sounds in the frequency range of 2000 Hz or less can be improved by setting the _{resonance frequency (f 0) to a value higher than a certain level.} Then, based on this idea, in accordance with the above-mentioned mathematical formula 10, in a soundproof material provided with an elastic sheet and a support portion for supporting the sheet and partitioning the sheet into compartments, the size and shape of the compartments are determined. By variously changing the material and film thickness of the sheet in the compartment _{, a large number of soundproofing materials having different resonance frequencies (f 0} ) were produced, and the soundproofing performance of each of them (particularly in the frequency range of 2000 Hz or less) was evaluated. As a result, the surface rigidity of the sheet (k; calculated by the above formula 5) and the surface density of the sheet (m; calculated by the above formula 9) in the compartment satisfy the relationship of the following formula 1. In particular, it was confirmed that excellent soundproofing performance can be exhibited even in the frequency range of 2000 Hz or less. The following formula 1 means that the resonance frequency (f ₀ ) calculated based on the above approximation is larger than 900 [Hz].

Here, the form of the value on the left side in Equation 1 is not particularly limited, and can be appropriately set according to the frequency region in which the soundproofing material is desired to exhibit soundproofing performance. In general, the larger the value on the left side in Equation 1, the higher the resonance frequency shifts to the higher frequency side. Therefore, the resonance frequency may be appropriately set in consideration of this. As an example, the value on the left side in Equation 1 is preferably 1400 Hz or higher, more preferably 2000 Hz or higher, still more preferably 3000 Hz or higher, even more preferably 4000 Hz or higher, and particularly preferably 5000 Hz or higher. The value on the left side in Equation 1 is, for example, 10000 Hz or higher, for example, 50,000 Hz or higher, and for example, 100,000 Hz or higher. In the soundproofing material exhibiting soundproofing performance within the scope of the technical idea according to the present invention, the upper limit of the value on the left side in Equation 1 is preferably 1000000 Hz or less, more preferably 800,000 Hz or less, and further. It is preferably 600,000 Hz or less.

By the way, in the technique disclosed in Non-Patent Document 1, as a result of the cell size being too large, the surface rigidity of the elastic sheet becomes small, and ^{the value of (k / m) 1/2} / 2π does not become sufficiently large. Therefore, it is considered that excellent soundproofing performance cannot be exhibited especially in the frequency range of 2000 Hz or less.

Further, conventionally, resin structures composed of a core layer in which a plurality of cells are arranged side by side and skin layers arranged on both sides of the core layer have been proposed for various purposes, and the resin structure absorbs sound. Attempts have also been made to provide properties and sound insulation. However, the conventional technique intended to give such a resin structure sound absorption and sound insulation presupposes that the skin layer is provided with communication holes for communicating the inside and outside of the cells constituting the core layer. There is. Further, even when the skin layer is provided with the communication holes in this way, it is also impossible to sufficiently secure the surface rigidity of the sheet having elasticity. As a result, the value of (k / m) ^1/2 / 2π does not become sufficiently large, so that excellent soundproofing performance cannot be exhibited especially in the frequency range of 2000 Hz or less. On the other hand, in a resin structure having the same structure as described above, techniques that do not presuppose the provision of communication holes as described above in the skin layer have been conventionally proposed, but these techniques relate to sound absorption, sound insulation, soundproofing, and the like. It's not a thing. Some of these technologies are intended to be applied to applications requiring rigidity such as containers, shelves, pallets, and panels for the purpose of improving mechanical strength such as bending rigidity and bending strength. .. Furthermore, in another proposal using a similar resin structure, the skin layer is required to contain an impact resistance improving material for reducing the elastic modulus of the skin layer. There is a high possibility that it does not correspond to the "elastic sheet" in the present invention. Further, in yet another proposal using the same resin structure, a metal member having a thickness of about 0.05 to several mm is arranged as the skin layer, and a material having high rigidity is also used for the skin layer. .. Therefore, in the prior art relating to the resin structure in which the skin layer is not provided with the communication holes, the value of the surface rigidity in the present invention becomes too large, and as a result, the value of (k / m) ^1/2 / 2π cannot be measured. It is considered that the value will be large (on the high frequency side).

Hereinafter, the components of the soundproofing material 10 will be described in more detail.

(Sheet with elasticity)
The constituent materials of the elastic sheet (corresponding to the latex rubber sheet 200 shown in FIGS. 1 and 2) are not particularly limited, and various materials can be used as long as they are elastic materials. As used herein, the term "elastic" means that the sheet is composed of a material whose Young's modulus value is in the range of 0.001 to 70 [GPa]. The Young's modulus value can be measured by JIS K7161-1 (2014) for resins. The Young's modulus of the metal can be measured by JIS Z2241 (2011). The Young's modulus of rubber can be measured by JIS Z6251 (2010). As the constituent material of the elastic sheet, in addition to the latex rubber used in the above-described embodiment, chloroprene rubber (CR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene Rubber materials such as rubber (NBR) can be used as well. Further, a resin material, a metal material, a paper material, or the like may be used as an elastic sheet. In addition, cushioning materials such as air cushions can also be used. All of these materials, including the rubber material, have high elasticity to the extent that the effect of the soundproofing material according to the present embodiment can be exhibited. Resin materials include polyethylene (for example, low-density polyethylene, high-density polyethylene, etc.), polyolefin resin such as polypropylene, polyvinyl chloride resin, acrylic resin, methacrylic resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin, ethylene-acetic acid. Examples thereof include vinyl resin and styrene-butadiene resin. Further, as the thermosetting resin, silicone resin, urethane resin, melamine resin, thermosetting acrylic resin, urea resin, phenol resin, resorcin resin, alkylresorcin resin, epoxy resin, thermosetting polyester and the like can be used. In addition, urethane resin prepolymer, urea resin prepolymer (initial condensate), phenol resin prepolymer (initial condensate), diallyl phthalate prepolymer, acrylic oligomer, polyvalent isocyanate, methacrylic ester monomer, which produce these resins, Prepolymers such as diallyl phthalate monomers and resin precursors such as oligomers and monomers may be used. Examples of the metal material include copper and aluminum. The constituent material of the elastic sheet is not limited to the above, and other materials may of course be used. A rubber material is preferable as a constituent material of the elastic sheet, and latex rubber or EPDM rubber is more preferable. By using these rubber materials as a constituent material of an elastic sheet, the soundproofing effect of the soundproofing body according to the present invention can be suitably exhibited. In addition, these rubber materials are particularly preferable because they are lightweight and contribute significantly to fuel efficiency, especially when considering application to vehicle applications. Further, from the viewpoint of cost reduction, a polyolefin resin such as polypropylene is also preferable as a constituent material of an elastic sheet.

The film thickness of the elastic sheet is preferably 10 to 1000 μm, more preferably 100 to 500 μm, from the viewpoint of the soundproofing effect of the soundproofing material.

(Support part (lattice structure))
The support portion has a function of supporting the elastic sheet described above. This support is composed of a plurality of hollow cells that partition the elastic sheet described above into a plurality of (airtightly partitioned) compartments. As long as it has a configuration capable of exhibiting such a function, there is no particular limitation on the specific configuration of the support portion.

The constituent material of the support portion is not particularly limited, and in addition to the polypropylene resin used in the above-described embodiment, a conventionally known thermoplastic resin or thermosetting resin can be used. Further, a metal material or other material may be used as a constituent material of the support portion. All of these materials have physical properties suitable for holding an elastic sheet and partitioning it into compartments.

The thermoplastic resin includes polypropylene resin, polyolefin resin such as polyethylene (for example, low density polyethylene, high density polyethylene, etc.), polyvinyl chloride resin, acrylic resin, methacrylic resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin. , Ethylene-vinyl acetate resin, styrene-butadiene resin and the like are exemplified. Further, as the thermosetting resin, urethane resin, melamine resin, thermosetting acrylic resin, urea resin, phenol resin, resorcin resin, alkylresorcin resin, epoxy resin, thermosetting polyester and the like can be used. In addition, urethane resin prepolymer, urea resin prepolymer (initial condensate), phenol resin prepolymer (initial condensate), diallyl phthalate prepolymer, acrylic oligomer, polyvalent isocyanate, methacrylic ester monomer, which produce these resins, Prepolymers such as diallyl phthalate monomers and resin precursors such as oligomers and monomers may be used. Among them, a thermoplastic resin is preferably used from the viewpoint of easy molding, and a vinyl chloride resin or a polyolefin resin is particularly preferable because it is lightweight, has excellent durability, and is inexpensive.

As described above, in the embodiments shown in FIGS. 1 to 3, the support portion is composed of a plurality of grid-like structures having a plurality of hollow cells arranged continuously (regularly). Then, at least a part of the plurality of hollow cells constituting the support portion constitutes a lattice-like structure in which the hollow cells having the same cross-sectional shape perpendicular to the extending direction are regularly arranged. Is preferable. With such a configuration, it is easy to manufacture, and the soundproofing performance against sound waves in a desired frequency range can be specifically exhibited by the presence of a large number of compartments having the same shape. At this time, from the viewpoint of further exerting the soundproofing performance, the ratio of the area of the lattice structure to the area of the support portion is preferably 80 to 100%, more preferably 90 to 100%. It is more preferably 95 to 100%, even more preferably 98 to 100%, particularly preferably 99 to 100%, and most preferably 100%.

The cross-sectional shape of the hollow cell in the above-mentioned lattice structure (cross-sectional shape of the hollow cell in the cross section perpendicular to the extending direction of the hollow cell) is not limited to the rectangle as shown in FIGS. 2 and 3, and other shapes. It may be. If a large number of tubular cells are arranged by continuously forming regular polygons with the same cross-sectional shape, in addition to rectangles, regular squares, equilateral triangles, and regular hexagons are used as the cross-sectional shapes. Can be done. By adopting these shapes, a support that is easy to manufacture and exhibits excellent strength can be provided. Further, the cross-sectional shape of the hollow cell may be circular or elliptical. If the cross section of the grid-like structure is a pattern in which a plurality of regular polygons are regularly arranged, for example, by the plane filling method of Archimedes (4 squares, 1 square), ( 3 regular triangles, 2 regular squares) x 2 ways, (1 regular triangle, 2 regular squares, 1 regular hexagon), (2 regular triangles, 2 regular hexagons), ( 1 regular triangle, 2 regular hexagons), (1 regular square (square), 1 regular hexagon, 1 regular hexagon), (1 regular square (square), 2 regular octagons) By any combination, the cross section of the lattice structure can be configured to have the above pattern.

The size of the hollow cells forming the lattice structure is not particularly limited as long as it satisfies the above-mentioned formula 1. The wall thickness of the hollow cell is preferably 10 to 150 μm, more preferably 30 to 100 μm.

In this embodiment, the larger the height of the grid-like structure (support portion) in the extending direction, the more excellent soundproofing performance tends to be exhibited over a wide range in the low frequency range of 2000 Hz or less. From this point of view, the grid-like structure (support portion) is preferably a structure having a uniform height. Further, in this case, the height of the lattice structure in the extending direction is preferably 5 mm or more, more preferably 6 mm or more, still more preferably 13 mm or more, still more preferably 19 mm or more. It is particularly preferably 22 mm or more, and most preferably 25 mm or more.

As described above, the soundproofing material according to this embodiment is preferably lightweight. In this respect, the surface density of the overall sound insulation according to the present embodiment is preferably less than 3.24kg / ^{m 2,} more preferably not more than 2.0 kg / ^{m 2,} more preferably 1.5 kg / It is m ² or less, and particularly preferably 1.0 kg / m ² or less.

The configuration of the soundproofing material according to the preferred embodiment of the present invention has been described above with reference to FIGS. 1 to 3, but the present invention is not limited to these embodiments and may be modified as appropriate. For example, as shown in FIGS. 9 and 10, for connecting the plurality of grid-like structures 100 to each other on an opening cross section (upper surface in each figure) of the plurality of grid-like structures 100 on the side opposite to the substrate 20. A connecting portion (here, elastic tape 30) may be provided. With such a configuration, it is possible to suppress a decrease in the strength of the soundproofing material 10 due to the plurality of lattice-like structures 100 constituting the soundproofing material 10 being separated from each other as they move toward the opposite side of the substrate 20. ..

Further, in FIGS. 1 to 3, a case where a plurality of hollow cells 100a are regularly arranged to form a grid-like structure 100 has been described as an example, but the plurality of hollow cells 100a are not necessarily in a grid pattern. It is not necessary to construct the structure 100, and it may be arranged on an elastic sheet so as to exist independently of other hollow cells. Examples of such a form include, as shown in FIG. 11A, a form in which a plurality of hollow cells 100a having a circular cross-sectional shape are arranged so as to exist independently of the other hollow cells 100a. FIG. 11B is an example in which the cross-sectional shape of the hollow cell 100a is square. Even with such a configuration, the action and effect of the soundproof structure according to the present embodiment can be similarly exhibited.

Further, when a plurality of hollow cells 100a are regularly arranged to form a lattice-like structure 100 and the plurality of lattice-like structures 100 are arranged on an elastic sheet so as to exist independently of each other. The pattern in which a plurality of lattice-like structures independent of each other are arranged is not limited to the form shown in FIG. For example, as shown in FIG. 12A, a form in which a plurality of grid-like structures are independently arranged so as to be divided into a cross along a line connecting the midpoints of the opposite sides of the rectangular support is exemplified. Will be done. Further, FIG. 12B shows a state in which four lattice-like structures arranged so as to exist independently of each other shown in FIG. 12A are connected by using a connecting portion (here, elastic tape).

Further, when a plurality of hollow cells 100a are regularly arranged to form a lattice-like structure 100, and the plurality of lattice-like structures 100 are arranged on an elastic sheet so as to exist independently of each other. The grid-like structure 100 may have a notch portion along the extending direction of the hollow cell 100a in the opening cross section on the side opposite to the substrate 20. For example, the soundproofing material 10 shown in FIG. 13A has a grid-like structure 100 similar to the soundproofing material shown in FIG. 2, but has an opening cross section on the side opposite to the substrate 20 of the grid-like structure 100. A notch 100b is provided along the extending direction of the hollow cell 100a. By providing such a notch portion 30, the grid-like structure 100 is easily deformed so that the notch portion is opened. As a result, when the soundproofing material 10 is arranged on the substrate 20 having a curved surface in which the grid-like structure 100 is deformed so that the notch portion is opened, it becomes easier to follow the case, and the effect of the present invention becomes more remarkable. Can be expressed. The pattern for providing the notch is not limited to the form shown in FIG. 13A, and the soundproof structure according to the present invention may be configured by providing the notch in the support portion composed of a single lattice-like structure. For example, as shown in FIG. 13B, notches may be provided in a cross shape along the diagonal line of the rectangular grid-like structure, or as shown in FIG. 13C, in the opposite sides of the rectangular grid-like structure. A notch may be provided in a cross shape along a line connecting the points.

Further, the substrate may have an opening. In such a case, the arrangement of the soundproofing material on the substrate is not particularly limited, but the elastic sheet is fixed to the substrate along the peripheral edge of the opening so that the soundproofing material covers the opening of the substrate. Is preferable. According to such a configuration, even when the substrate has an opening, the soundproofing material can be reliably made to follow the curved surface existing in the portion other than the opening. At this time, another member such as a rubber sheet may be arranged between the sheet and the substrate (peripheral portion of the opening) as a fixing means, but such a portion corresponding to the opening may be arranged. It is preferable not to arrange another member. Further, even when the substrate does not have an opening, a fixing means such as a rubber sheet may be arranged between the elastic sheet and the substrate.

The soundproofing material according to this embodiment can be suitably used for shielding noise derived from various sound sources by arranging the soundproofing material on a substrate to form a soundproofing structure.

As the substrate constituting the soundproof structure, basically a non-breathable metal plate (iron plate, aluminum plate, etc.), a resin plate, or the like can be used. The thickness of the substrate is preferably in the range of 0.5 to 2.0 mm in the case of a metal plate, and preferably in the range of 0.5 to 20 mm in the case of a resin plate.

The substrate constituting the soundproof structure according to this embodiment has a curved surface. The "curved surface" means an arbitrary surface shape other than a flat surface, but is preferably a curved surface that protrudes (convex) with respect to the side on which the soundproofing material is arranged.

There is no particular limitation on the radius of curvature and the size of the bending depth of the curved surface of the substrate, and any value is adopted according to the shape of the portion to which the soundproofing material is applied. A substrate having a bent surface may have a twisted structure on its curved surface. The term "twist" as used herein means a shape obtained when the radius of curvature of a curved surface is not constant or the opening angle is not constant. Further, the substrate having a curved surface may have a flat surface at a portion other than the curved surface.

The soundproofing material according to this embodiment and the soundproofing structure using the soundproofing material can be constructed to be extremely lightweight. Since the soundproofing material and the soundproofing structure according to the present embodiment can be reduced in weight in this way, it is preferable that the soundproofing material and the soundproofing structure are mounted on a vehicle and used. In particular, it is most preferably applied to a soundproofing application against noise generated from a part (inherent sound source) that generates a loud sound such as an engine, a transmission, and a drive system. As an example of the application site, in the engine compartment, it can be applied to an engine head cover, an engine body cover, a hood insulator, an insulator in front of a dash, a partition wall of an air box, an air cleaner of an air intake, a dust side duct, an undercover and the like. In the cabin, dash insulators, dash panels, floor carpets, spacers, door trims for doors, soundproofing materials in door trims, soundproofing materials in compartments, instrument panels, instrument center boxes, instapper boxes, air conditioner housings, etc. Roof trim, soundproofing material in roof trim, sun visor, air conditioning duct for rear seats, cooling duct of battery cooling system in battery-equipped vehicles, cooling fan, center console trim, soundproofing material in console, parcel trim, parcel panel , Seat headrest, front seat back, rear seat back, etc. Further, in the trunk, it can be applied to a trunk floor trim, a trunk board, a trunk side trim, a soundproofing material in the trim, a drafter cover, and the like. It can also be applied within the skeleton of a vehicle or between panels, and can be applied to, for example, pillar trims and fenders. Furthermore, it can be applied to each member outside the vehicle, for example, an undercover under the floor, a fender protector, a back door, a wheel cover, an aerodynamic cover of a suspension, and the like. Therefore, as the substrate constituting the soundproof structure, a metal plate, a resin plate, or the like as a constituent material of the various application parts described above can be used as it is.

There is no particular limitation on the arrangement form when the soundproof structure according to this embodiment is arranged with respect to the sound source. When arranging the soundproof structure according to the present embodiment with respect to the sound source, it is preferable to arrange the soundproof structure so that the sound source is located in the extending direction of the hollow cells constituting the grid-like structure (support portion). Further, when arranging in this way, the elastic sheet constituting the soundproofing material may be arranged so as to be located on the sound source side, or the opening of the tubular cell constituting the soundproofing material may be arranged on the sound source side. It may be arranged so as to be located.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the technical scope of the present invention is not limited to the following examples.

<< Evaluation of soundproofing performance of soundproofing structure >>
The soundproofing performance of the soundproofing structures produced in Examples and Comparative Examples described later was measured for sound waves at each frequency. Specifically, as shown in FIG. 14, a sound insulation box made of an iron jar having a curved enclosure around the opening is prepared, and the enclosure having this curved surface is regarded as a substrate, and examples and comparative examples are used. The performance of the soundproofing material was evaluated. Specifically, a speaker (sound source) was placed inside the sound insulation box prepared above, and a sample (soundproof material) was placed at the opening of the sound insulation box. Further, in order to prevent sound leakage from the periphery of the sample (soundproof material) at the opening of the sound insulation box, a rubber sheet was arranged around the sample (soundproof material). Then, the soundproofing performance is evaluated by generating sound from the speaker (sound source) installed inside the soundproofing box and measuring the insertion loss [unit: dB] for the case where the sample (soundproofing material) is not placed (control). did. The larger the value of the insertion loss at a certain frequency, the better the soundproofing performance against the sound wave at that frequency. The conditions for generating the sound source were as follows:
Spectrum level: White noise (100-8192Hz)
F _max : 8192Hz
Average value: 300 times of addition average (300 measurements were performed while shifting the time little by little in one measurement, and the addition average was used as the measured value).
Overlap: 75%.

<< Production of soundproofing material >>
[Comparison example]
An elastic sheet (latex rubber sheet; film thickness 0.25 mm) and a substantially square honeycomb structure made of polyvinyl chloride (PVC) (honeycomb support having a large number of regular hexagonal cross sections) (support thickness) 25 mm) and prepared. Here, the size of the hollow cells constituting the honeycomb structure (distance between the opposing parallel sides in the regular hexagon of the cross-sectional shape of the honeycomb structure) was set to 4 mm. Next, the opening cross section of the honeycomb structure was airtightly adhered to one surface of the sheet to prepare a soundproofing material of the present comparative example having a flat plate-like structure.

The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 15A shows a photograph of the soundproofing performance of the soundproofing material evaluated. As shown in FIG. 15A, when the soundproofing material of this comparative example is arranged, there is a portion where the enclosure having a curved surface resembling a substrate and the normal of the section defined by the hollow cell are not substantially vertical. Occurred.

Here, with respect to this comparative example, the result of the insertion loss obtained by evaluating the soundproofing performance is shown in FIG. 15B. In the result shown in FIG. 15B, the straight line graph shows a graph of the insertion loss assumed when the soundproofing material of this comparative example follows the mass law (the same applies hereinafter).

[Example 1]
A grid-like structure as shown in FIG. 2 was produced by utilizing extrusion molding. More specifically, a lattice structure in which 40 hollow cells having a substantially square shape (size is about 1 cm square) are arranged is produced by extrusion molding of polypropylene, and cut to a length corresponding to the height of the lattice structure. did. Next, 16 of the cut lattice-like structures were laminated so that the hollow cells were regularly arranged, and all the laminated surfaces were adhered with an adhesive to prepare a lattice-like structure. Two identical lattice-like structures are prepared, arranged side by side on one surface of an elastic sheet (sheet made of latex rubber; film thickness 0.25 mm), and the open cross section of the lattice-like structure is airtightly bonded. The soundproofing material of this example was prepared. The thus-obtained deadening the overall surface density of 4.99 kg / ^{m 2,} the surface density of the support is 4.75 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 42248 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2101 Hz. FIG. 16A shows a photograph of the soundproofing performance of the soundproofing material evaluated. As shown in FIG. 16A, when the soundproofing material of the present embodiment is arranged, the enclosure having a curved surface resembling a substrate and the normal of the section defined by the hollow cell are substantially vertical in all the portions. It became.

Here, for this embodiment, the result of the insertion loss obtained by evaluating the soundproofing performance is shown in FIG. 16B.

[Example 2]
In the soundproofing material of the above-mentioned comparative example, the soundproofing material of the present embodiment was produced by the same method as that of the above-mentioned comparative example except that the X-shaped notch portion as shown in FIG. 13B was formed in the support portion. The depth of the notch was 80% of the thickness of the support. The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 17 shows the result of the insertion loss obtained by evaluating the soundproofing performance of this embodiment.

[Example 3]
In the soundproofing material of the above-mentioned comparative example, the soundproofing material of the present embodiment was produced by the same method as that of the above-mentioned comparative example except that a cross cutout portion as shown in FIG. 13C was formed in the support portion. The depth of the notch was 80% of the thickness of the support. The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 18 shows the result of the insertion loss obtained by evaluating the soundproofing performance of this embodiment.

[Example 4]
In the soundproofing material of the comparative example described above, the support portion is divided into four grid-like structures as shown in FIG. 12A and arranged on the sheet so that they exist independently of each other. The soundproofing material of this example was produced by the same method as in the above. The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 19 shows the result of the insertion loss obtained by evaluating the soundproofing performance of this embodiment.

[Example 5]
In the soundproofing material of Example 4 described above, the same method as in Example 4 described above is used except that the adjacent portions of the lattice-like structures existing independently of each other are connected by using a metal leaf tape as a connecting portion. The soundproofing material of this example was produced. The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 20 shows the result of the insertion loss obtained by evaluating the soundproofing performance of this embodiment.

[Example 6]
In the soundproofing material of the above-mentioned Example 4, the same as the above-mentioned Example 4 except that the adjacent portions of the lattice-like structures existing independently of each other are connected by using the elastic tape (Kapton tape) as the connecting portion. The soundproofing material of this example was produced by the method of. The thus-obtained deadening the overall surface density of 1.88 kg / ^{m 2,} the surface density of the support is 1.64 kg / ^{m 2,} the surface density m of the sheet 0.24 kg / ^{m 2,} the sheet The surface density k was 82474 N / mm, and ^{the value of (k / m) 1/2} / 2π was 2935 Hz. FIG. 21 shows the result of the insertion loss obtained by evaluating the soundproofing performance of this embodiment.

As can be seen from the results of the above-mentioned insertion loss graph, the soundproofing material of each example has a higher insertion loss value over a wide range of the frequency range of 2000 Hz or less (particularly 1000 Hz or less) as compared with the soundproofing material of the comparative example. showed that. Therefore, according to the soundproof structure according to the embodiment of the present invention, it can be seen that high soundproof performance can be exhibited over a wide range of the frequency range of 2000 Hz or less even when applied to a substrate having a curved surface. .. In addition, it can be expected to suppress a decrease in strength against an external force.

1 Soundproof structure,
10 Soundproofing material,
20 boards,
30 Elastic tape (connecting part)
100 Lattice structure (support part),
100a hollow cell,
100b notch,
110 Latex rubber sheet (elastic sheet),
h The normal of the compartment partitioned by the hollow cell.

Claims (7)

A board with a curved surface and
A sheet having elasticity and a support portion formed of a plurality of hollow cells for partitioning the sheet into a plurality of compartments to support the sheet are provided, and the surface rigidity (k) of the sheet in the compartment and the sheet are provided. The surface density (m) of the above satisfies the relationship of the following formula 1, and the soundproofing material arranged on the substrate and
Have,
The soundproofing so that the sheet is arranged on the substrate side with respect to the support portion and the normal of the compartmentalized portion partitioned by each of the hollow cells is substantially perpendicular to the substrate. Soundproof structure in which the material is arranged on the substrate:

The soundproof structure according to claim 1, wherein at least a part of the hollow cell constituting the support portion is arranged on the sheet so as to exist independently of other hollow cells. The first aspect of the present invention, wherein at least a part of the plurality of hollow cells constitutes a lattice-like structure in which the hollow cells having the same cross-sectional shape perpendicular to the extending direction are regularly arranged. Soundproof structure. The soundproof structure according to claim 3, wherein the lattice-like structure has a cutout portion along the extending direction of the hollow cell in an opening cross section on the opposite side of the substrate. The support portion has a plurality of the lattice-like structures, and the support portion has a plurality of the lattice-like structures.
The soundproof structure according to claim 3, wherein the plurality of lattice-like structures are arranged on the sheet so as to exist independently of each other. The soundproof structure according to claim 5, wherein a connecting portion for connecting the plurality of lattice-like structures to each other is provided in an opening cross section of the plurality of lattice-like structures on the side opposite to the substrate. The substrate has an opening
The soundproof structure according to any one of claims 1 to 6, wherein the sheet is fixed to the substrate along the peripheral edge of the opening so that the soundproof material covers the opening.

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