JP2018131013A - Soundproof material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soundproof material which improves sound insulation performance only in a necessary portion with a simple structure to attain high soundproof performance as a whole while attaining sound absorption performance with a sound absorption material.SOLUTION: In a sheet-like soundproof material 10 formed by a sound absorption material including air, a sound insulation improvement part 15 which compressively deforms in a thickness direction to attain surface density higher than that of other portions of the soundproof material 10 is provided.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a soundproofing material provided in, for example, a vehicle door, and particularly relates to a technical field of a structure capable of changing sound absorption performance and sound insulation performance depending on a portion.

  Conventionally, soundproofing materials have been used in various fields. For example, in the field of automobiles, as disclosed in Patent Documents 1 and 2, a sealing material for sealing a door hole formed in an inner panel of a door. It is used as That is, a door hole such as a service hole is formed in the inner panel of the door, and the door hole seal material is provided with a soundproofing performance in order to prevent noise outside the vehicle compartment from entering the vehicle compartment through the door hole. In this way, the passenger compartment is quieted.

  In the peripheral part of the sealing material of the door hole of Patent Document 1, an adhesive part that is bonded to the inner panel is provided. The adhesive portion is formed in a step shape bulging from the other part of the sealing material, and is formed thinner than the other part of the sealing material.

  The sealing material of Patent Document 2 has a multilayer structure including a core layer made of an elastic material and inelastic skin layers provided on both sides in the thickness direction of the core layer. A bulging portion bulging so as to avoid the protruding portion is formed in a portion corresponding to the protruding portion of the interior trim in the sealing material. The bulging part is formed by plastically deforming the skin layer.

JP 2005-47377 A JP 2007-290668 A

  In Patent Document 1, the adhesive part is formed in a stepped shape and swelled from the other part of the sealing material, that is, is stretched, which means that the surface density is lowered and the sound insulation performance is inevitably lowered at the part. Resulting in. Similarly, in Patent Document 2, since the skin layer is plastically deformed to form the bulging portion, the skin layer is stretched and thinned, thereby reducing the surface density and reducing the sound insulation performance. End up. That is, in both Patent Documents 1 and 2, the sound insulation performance of the portion where the bonding portion and the bulging portion are formed is lower than that of the other portions.

  By the way, for example, when considering the soundproofing of the door of an automobile, the noise from the outside of the passenger compartment includes sounds in various frequency bands from a low frequency range to a high frequency range, and noise with a lot of low frequency components depending on the part of the door. There are places that are easy to enter, and places that are not. In the case of sealing materials for door holes as in Patent Documents 1 and 2, in general, sound absorption performance that reduces noise entering the passenger compartment by absorbing sound into the sealing material, and noise that enters the passenger compartment by sound insulation by the sealing material is reduced. Sound insulation performance can be obtained by using sound insulation performance, but it is difficult to absorb noise with a lot of low frequency components with thin objects such as door hole seal materials. Will do.

  However, in Patent Document 1, the bonded portion is necessarily a portion having a low sound insulation performance, and in Patent Document 2, the bulging portion is necessarily a portion having a low sound insulation performance, so these portions are likely to receive noise with a lot of low frequency components. If it is a portion, the soundproofing performance is degraded.

  On the other hand, it is conceivable to improve the sound insulation performance partially by separately arranging a sound insulation member having a large specific gravity, etc., but the weight increases, the number of parts increases and the assembly man-hour increases. This increases the cost and is not preferable.

  The present invention has been made in view of the above points, and the object of the present invention is to obtain a sound absorbing performance by a sound absorbing material, while improving the sound insulating performance only for necessary portions with a simple structure, and to achieve a high soundproof performance as a whole. There is to get.

  In order to achieve the above object, in the present invention, a part of the sound-absorbing material containing air is compressed and deformed to provide a portion having a relatively high surface density to partially improve the sound insulation performance.

  1st invention is a sheet-like soundproof material which consists of a sound-absorbing material containing air, Comprising: The said soundproof material was compressively deformed in the thickness direction and the surface density was raised rather than the other part of this soundproof material. A sound insulation improving part is provided.

  According to this configuration, since the soundproof material is made of a sound absorbing material containing air, high sound absorbing performance can be obtained. Thereby, entering into a room etc. is suppressed by absorbing noise. In addition, the noise includes, for example, noise with a lot of low frequency components, and the noise with a lot of low frequency components may enter a part of the soundproofing material. In this case, since the surface density of the sound insulation improving portion is increased by arranging the sound insulation improving portion in the portion where the noise having a lot of low frequency components is incident, the noise having a lot of low frequency components is sound insulated. . In addition, some of the noise having a lot of low frequency components is absorbed by the soundproofing material. Therefore, the soundproof performance is enhanced by the sound absorption performance and the sound insulation performance.

  In addition, since the sound insulation improving portion is obtained by compressing and deforming a part of the soundproof material, it is not necessary to provide a separate part with a high specific gravity and can be realized with a simple structure.

  According to a second invention, in the first invention, the soundproofing material has a foam structure having a large number of bubbles, and the sound insulation improving portion is compressed so that a bubble ratio is smaller than other portions of the soundproofing material. It is deformed.

  According to this configuration, the soundproofing material has a foam structure, so that high sound absorption performance can be obtained while being lightweight. Moreover, since the bubble ratio of the sound insulation improvement part is small, the surface density is improved and the sound insulation performance is enhanced. The bubble ratio can be calculated, for example, by measuring specific gravity, the ratio of the total volume of bubbles per unit volume, or the ratio of the total opening area of bubbles opened per unit area in the cross section. However, it is not restricted to these, It can calculate by the calculation method of various bubble ratios.

  According to a third invention, in the second invention, the soundproof material includes a core layer having a large number of bubbles, and skin layers provided on both sides in the thickness direction of the core layer, The core layer is compressively deformed.

  According to this configuration, since the core layer is protected by the skin layer, it becomes difficult for water or the like to enter the air bubbles in the core layer, and a decrease in sound absorption performance is suppressed over a long period of time. Moreover, a sound insulation improvement part with a high surface density is obtained by compressively deforming a core layer.

  According to a fourth invention, in any one of the first to third inventions, a plurality of grooves are formed on a side surface of the soundproof material, and a depth of the groove formed in the sound insulation improvement portion is as follows. The depth of the groove formed in the other part is shallower.

  According to this configuration, the sound absorbing effect is further enhanced by forming a large number of grooves on the side surface of the soundproofing material. In addition, in the sound insulation improving portion, it is only necessary to enhance the sound insulation effect rather than the sound absorption effect. For this reason, it is possible to reliably improve the surface density by relatively reducing the depth of the groove.

  According to a fifth invention, in any one of the first to fourth inventions, the soundproof material is formed so as to close a door hole formed in a door of an automobile and is attached to the door, thereby improving the sound insulation performance. The portion is provided so as to be disposed on the belt line portion side of the door.

  According to this configuration, the soundproofing material can be used as a sealant for a door hole formed on the door of the automobile. At this time, there may be a tendency that noise with a lot of low frequency components tends to enter the passenger compartment from the vicinity of the beltline part of the door, but in this case, by arranging the sound insulation improvement part on the beltline part side of the door, Noise with many low-frequency components is effectively insulated.

  According to the first aspect of the invention, since the sound insulation performance improving portion that is compressed and deformed to increase the surface density is provided in a part of the sound insulation material containing air, it is necessary with a simple structure while obtaining the sound absorption performance by the sound insulation material. It is possible to improve the sound insulation performance of only the part and obtain a high sound insulation performance as a whole.

  According to the second invention, since the sound insulating material has a foam structure and the sound insulating property improving portion is compressed and deformed so as to reduce the bubble ratio, high sound insulating performance can be obtained while achieving weight reduction.

  According to the third invention, since the soundproof material has the core layer and the skin layer, the durability can be enhanced. Moreover, the core layer of the sound insulation improvement part can be compressed and deformed to obtain a sound insulation improvement part having a high surface density.

  According to the fourth invention, the sound absorbing performance can be enhanced by forming a large number of grooves. Moreover, by making the depth of the groove formed in the sound insulation improvement portion relatively shallow, it is possible to reliably increase the surface density and obtain a high sound insulation improvement portion.

  According to the fifth aspect of the present invention, when a door hole formed in the door of the automobile is closed by the soundproof material, it is possible to effectively insulate noise with a lot of low frequency components that enters from the vicinity of the belt line portion of the door.

It is a side view of the motor vehicle provided with the soundproof material which concerns on embodiment. It is the II-II sectional view taken on the line in FIG. It is a side view of a soundproof material. It is the IV-IV sectional view taken on the line in FIG. FIG. 5 is a view corresponding to FIG. 4 before compression deformation. It is a graph which shows the transmission loss of the soundproof material of this invention, and the soundproof material of a comparative example. It is a graph which shows the noise test result of the soundproof material of this invention, and the soundproof material of a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a side view of an automobile 100 to which soundproof materials 10 and 20 according to an embodiment of the present invention are attached. A front door 110 and a rear door 120 are provided on the side of the automobile 100. The front door 110 includes a door main body 111 and a door glass 112 provided so as to be movable up and down with respect to the door main body 111. As shown in FIG. 2, the door main body 111 of the front door 110 includes an outer panel 113 that constitutes the vehicle interior side and an inner panel 114 that constitutes the vehicle interior side. A door glass 112 in a lowered state is accommodated between the outer panel 113 and the inner panel 114. Between the outer panel 113 and the inner panel 114, there are disposed a rail 115 for guiding the door glass 112 in the vertical direction when moving up and down, and a window regulator 116 for moving the door glass 112 up and down.

  A door hole 114 a is formed in the inner panel 114 of the front door 110. The door hole 114a is for inserting, for example, a window regulator 116 or the like into the door body 111 when the front door 110 is assembled, and is greatly opened in the inner panel 114. The soundproofing material 10 is a sheet-like member made of a sound absorbing material formed so as to close the door hole 114a, and can be attached to the inner panel 114 directly or via other members. ing. The soundproofing material 10 can be attached to the inner panel 114 using, for example, a double-sided tape, an adhesive, a clip, or the like.

  The belt line part 110a of the front door 110 is an upper part of the door main body part 111 and is a part extending in the vehicle front-rear direction. The belt line portion 110a is located at a height similar to the vicinity of the upper arm around the shoulder of the front seat occupant, and is the portion closest to the ear of the front occupant in the door main body 111.

  As shown in FIG. 1, the rear door 120 has the same basic structure as the front door 110 and includes a door main body 121 and a door glass 122. The door body 121 of the rear door 120 includes an outer panel 123 and an inner panel (not shown). A door hole 124 a is formed in the inner panel, and the door hole 124 a is closed by the soundproof material 20 like the front door 110. Further, the belt line part 120a of the rear door 120 is an upper part of the door main body part 121 and is a part extending in the vehicle front-rear direction.

  The soundproofing material 10 attached to the front door 110 and the soundproofing material 20 attached to the rear door 120 are only different in shape and are usually composed of the same member. 10 will be described in detail. In addition, the soundproof material 10 can also be used by attaching to a slide door or a hatch back door, for example.

(Configuration of soundproof material 10)
The soundproof material 10 is formed by extruding a raw material such as rubber, thermoplastic elastomer, or thermoplastic resin so as to form a sheet having a predetermined thickness, and is a sound absorbing material containing air. Examples of the rubber include synthetic rubbers such as ethylene / propylene / diene rubber (EPDM), chloroprene rubber (CR), styrene / butadiene rubber (SBR), and acrylonitrile / butadiene rubber (NBR). Examples of the thermoplastic elastomer include olefin (TPO) and styrene (TPS). Examples of the thermoplastic resin include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and ethylene vinyl acetate copolymer (EVA).

  As shown in FIG. 1, the external shape of the soundproof material 10 is set larger than the door hole 114 a of the inner panel 114. Thereby, the entire door hole 114a of the inner panel 114 is covered with the soundproofing material 10. Although it is preferable to cover the entire door hole 114a of the inner panel 114 with the soundproofing material 10, the soundproofing material 10 may have a shape that does not cover a part of the doorhole 114a. Moreover, although the thickness of the soundproof material 10 can be set to 8 mm, for example, it is not restricted to this, For example, it can set to 4 mm or more and 15 mm or less. Further, the thickness of the soundproof material 10 is changed between the belt line side portion and the other portions. This will be described later.

  As shown in FIG. 4, the soundproof material 10 has a three-layer structure. That is, the front side and the back side skin layers 11 and 12 made of a solid layer without bubbles are formed on the front side and the back side, respectively, and the front side skin layer 11 and the back side skin layer 12 are interposed between the front side and the back side skin layers 11 and 12. A foam layer (core layer) 13 is formed. The thicknesses of the front and back skin layers 11 and 12 are set to be thinner than the thickness of the foam layer 13. For example, it is preferable that the thickness of the front skin layer 11 is 1/5 or less of the thickness of the foam layer 13, whereby the thickness of the foam layer 13 occupying the soundproof material 10 is sufficiently secured and the sound absorbing performance is improved. Since there are no air bubbles in the front side and back side skin layers 11 and 12, the front side and back side skin layers 11 and 12 have a water-stopping property that prevents water and the like from passing therethrough. Moreover, the front side and back side skin layers 11 and 12 also have sound insulation. The thickness of the front side and back side skin layers 11 and 12 can be, for example, 0.5 mm or more and 1 mm, and the thickness of the foam layer 13 can be, for example, about 2 mm to 14 mm, more specifically, about 6 mm or more and 7 mm.

  The foam layer 13 has a foam structure having a large and small number of bubbles 13a, 13a,. As a form of formation of the bubbles 13a, for example, a continuous bubble (continuous bubble) structure in which the bubbles 13a are continuous may be used, or some of the bubbles 13a are continuous and other bubbles 13a are not continuous. A bubble (semi-continuous bubble) structure may be used, or a closed cell structure in which the bubbles 13a are not continuous may be used. The specific gravity of the foam layer 13 is preferably 0.05 or more and 0.15 or less, for example, but is not limited to this range. By making the soundproofing material 10 into a foam structure, high sound absorption performance can be obtained while being lightweight.

  A large number of grooves 14, 14,... Are formed on the surface of the soundproof material 10 on the front skin layer 11 side. By forming the groove 14, the sound absorption performance can be enhanced. The groove 14 may be omitted. A number of holes (not shown) may be formed instead of the grooves 14. Moreover, you may form both the groove | channel 14 and a hole. The grooves 14 may be formed on the surface on the back side skin layer 12 side.

  The soundproofing material 10 is provided with a sound insulating property improving portion 15 that is compressed and deformed in the thickness direction and has a higher surface density than other portions of the soundproofing material 10. The sound insulation improving part 15 is provided so as to be arranged on the belt line part 110 a side of the front door 110, that is, to be arranged on the upper side of the soundproof material 10. In FIG. 3, the hatched range is a portion of the front door 110 on the belt line portion 110 a side, and the sound insulation improving portion 15 is provided in the hatched range. Moreover, in FIG. 4, the sound insulation improvement part 15 is provided above the virtual line L1.

  Since the sound insulation improvement part 15 is made by compressing and deforming only a part of the soundproofing material 10 in the thickness direction, the thickness is thinner than other parts of the soundproofing material 10. When the soundproofing material 10 is compressed and deformed in the thickness direction, the foamed layer 13 is mainly compressed and deformed. As a result, the sound insulation improving portion 15 has the bubbles 13a smaller than other portions of the soundproofing material 10. The bubble rate is reduced. In addition, when the foam layer 13 is compressed and deformed, there are some in which the bubbles 13a become smaller than before the deformation and others disappear. By reducing the bubble ratio of the sound insulation improvement part 15, the surface density of the sound insulation improvement part 15 is improved as compared with other parts of the soundproof material 10, and the sound insulation performance is enhanced. The bubble ratio can be calculated, for example, by measuring specific gravity, the ratio of the total volume of bubbles per unit volume, or the ratio of the total opening area of bubbles opened per unit area in the cross section. However, it is not restricted to these, It can calculate by the calculation method of various bubble ratios.

  Moreover, since the sound insulation improvement part 15 is compressively deformed in the thickness direction, as shown in FIG. 4, the depth of the groove 14 formed in the sound insulation improvement part 15 is the other part of the sound insulation material 10. It becomes shallower than the depth of the groove formed.

  As shown in FIG. 4, the maximum thickness (thickness of the portion where the groove 14 is not formed) T1 of the sound insulation improving portion 15 is the maximum thickness (the portion where the groove 14 is not formed) of the other portions of the soundproofing material 10. Thickness) It is preferable to set it in the range of 60% to 80% of T2, but it is most preferable to set T1 to about 70% of T2. If it exceeds 80%, it is difficult to obtain the effect of improving sound insulation. If it is less than 60%, the effect of improving the sound insulation is enhanced. However, depending on the combination of the raw material and the bubbles to be formed, it is difficult to make it smaller than 60% even if heat compression described later is performed, and it is made smaller than 60%. For this reason, if the heat compression is continued forcibly, the material may be deteriorated, and the sound insulation performance may be lowered.

(Manufacturing method of the soundproofing material 10)
Next, the manufacturing method of the soundproof material 10 comprised as mentioned above is demonstrated. First, as shown in FIG. 5, a sheet-like sound absorbing material 40 having a large number of grooves 44 is formed. The sound absorbing material 40 has a foam layer 43, a front side skin layer 41, and a back side skin layer 42, and corresponds to the foam layer 13, the front side skin layer 11, and the back side skin layer 12 of the soundproof material 10, respectively.

  Thereafter, the portion of the sound absorbing material 40 above the virtual line L1 (shown in FIG. 5) is heated and compressed until it is softened or melted. By this compression, the surface density of the portion above the virtual line L1 in the sound absorbing material 40 is increased. Thereafter, by cooling, the shape is maintained while the surface density of the portion above the imaginary line L1 is increased as shown in FIG. 4, and this portion becomes the sound insulation improving portion 15, and the soundproofing material 10 is obtained.

  By using heat when molding the sound insulation improving portion 15, the shape at the time of compressive deformation can be maintained even after the compressive force is removed. Thereby, for example, since the sound insulation improvement part 15 can be held in a thin state in a state where the sound insulation material 10 is attached to the inner panel 114 of the front door 110, interference between the other members and the sound insulation material 10 is suppressed. Can do.

(Effect of embodiment)
Next, the operational effects of the present embodiment will be described. Since the soundproofing material 10 is made of a sound absorbing material containing air, high sound absorbing performance can be obtained. Thereby, entering into a room etc. is suppressed by absorbing noise. Further, the noise includes, for example, noise having a lot of low frequency components, and the noise having a lot of low frequency components may enter a part of the soundproofing material 10. In this case, since the surface density of the sound insulation improvement unit 15 is increased by arranging the sound insulation improvement unit 15 in a portion where noise with a lot of low frequency components is incident, noise with a lot of low frequency components is sound insulation. Is done. Further, a part of the noise having many low frequency components is absorbed by the soundproofing material 10. Therefore, the soundproof performance is enhanced by the sound absorption performance and the sound insulation performance.

  Moreover, since the sound insulation improvement part 15 is obtained by compressing and deforming a part of the soundproof material 10, it is not necessary to provide a high specific gravity separate part etc., and it is realizable with a simple structure.

  In FIG. 6, the result of having compared the transmission loss of the sound of this embodiment and a comparative example is shown. The vertical axis of the graph shown in FIG. 6 is sound transmission loss (dB), and the horizontal axis is frequency (Hz). The “present embodiment” in FIG. 6 is the soundproofing material 10 provided with the sound insulation improving part 15, and the “comparative example” is the sound absorbing material not provided with the sound insulation improving part 15 (shape as shown in FIG. 5). It is. The test piece of the present embodiment is a circular member with a diameter of 29 mm obtained by hollowing out the sound insulation improvement portion 15, and the test piece of the comparative example is a circular member with a diameter of 29 mm obtained by hollowing out the sound absorbing material shown in FIG. 5. is there. As can be seen from FIG. 6, in this embodiment, the sound transmission loss is increased in the low frequency band of 1000 Hz to 4000 Hz as compared with the comparative example, and a difference of about 2 dB at maximum occurs.

  The test method using this test piece is a normal incidence measurement method based on JIS 1405-2, and the measurement apparatus uses a 4206 measurement system manufactured by B & K.

  Moreover, in FIG. 7, the result compared about the noise test result of this embodiment and a comparative example is shown. The vertical axis of the graph shown in FIG. 7 is the sound pressure level (dB), and the horizontal axis is the frequency (Hz). “This embodiment” in FIG. 7 means that the soundproof material 10 provided with the sound insulation improvement unit 15 is attached to the actual front door 110 and travels in an actual vehicle, and at that time, noise is measured near the ear position of the driver's seat occupant. It is the result. The “comparative example” means that the sound absorbing material (the shape shown in FIG. 5) not provided with the sound insulation improvement unit 15 is attached to the actual front door 110 and travels in an actual vehicle, and at that time, the ear position of the driver's seat occupant It is the result of measuring noise in the vicinity.

  The measuring method is as follows. First, on the side of the driver's seat outside the vehicle, an omnidirectional speaker is installed at a height of 1.4 m at a distance of 2 m laterally from the door glass on the driver's seat side, and a sound of 250 Hz to 8 kHz is 80 to 90 dB. Outputs the sound pressure level. The microphone for collecting sound is arranged near the ear position of the driver's seat occupant in the passenger compartment.

  Both “this embodiment” and “comparative example” were attached so as to close the door hole 114a. As can be seen from FIG. 7, the sound pressure level is lowered particularly in the low frequency band of 800 Hz to 1000 Hz, and a difference of about 2 dB at maximum occurs. In addition, according to the prior measurement result, since the sound pressure level of the low frequency component near 1000 Hz tends to be high in the vicinity of the belt line portion 110a of the front door 110, the sound insulation performance improving portion 15 is on the belt line portion 110a side. The soundproofing material 10 was provided so that it might be arrange | positioned.

(Other embodiments)
Although the said embodiment demonstrated the case where the sound-insulation material 10 was comprised with the sound-absorbing material of the foam structure, you may comprise not only this but the sound-absorbing material consisting of a fiber. In this case, a sound absorbing material is configured by combining a large number of fibers so as to include air, and a part of the sound absorbing material is compressed and deformed in the thickness direction so as to have a higher surface density than other parts of the sound insulating material. What is necessary is just to provide a property improvement part.

  Moreover, in the said embodiment, although the soundproof material 10 is provided so that the sound-insulation improvement part 15 may be arrange | positioned at the beltline part 110a side, it is not restricted to this, The sound pressure level of the low frequency component of 1000 Hz vicinity is high. It is only necessary to provide the soundproofing material 10 so that the sound insulation improving portion 15 is disposed in the portion, and the soundproofing material can be changed according to the structure of the door.

  Moreover, although the said embodiment demonstrated the case where the soundproof material 10 was provided in the doors 110 and 120 of a motor vehicle, it can also provide in housings, such as not only this but various vehicles, such as a train, an airplane, a ship, etc., for example.

  The above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the soundproofing material according to the present invention can be provided in a vehicle, for example.

10 Soundproof material 11 Front side skin layer 12 Back side skin layer 13 Foam layer (core layer)
14 Groove 15 Sound insulation improvement part 110 Front door 110a Belt line part 114a Door hole

Claims (5)

A sheet-like soundproofing material made of a sound-absorbing material containing air,
The soundproofing material, wherein the soundproofing material is provided with a sound insulation improving portion that is compressed and deformed in the thickness direction and has a higher surface density than other parts of the soundproofing material. The soundproof material according to claim 1,
The soundproofing material has a foam structure having a large number of bubbles,
The sound insulating material, wherein the sound insulating property improving portion is compressed and deformed so that a bubble ratio is smaller than other portions of the sound insulating material. The soundproof material according to claim 2,
The soundproofing material has a core layer having a large number of bubbles, and a skin layer provided on both sides in the thickness direction of the core layer,
A soundproof material, wherein the core layer of the sound insulation improving portion is compressed and deformed. In the soundproof material according to any one of claims 1 to 3,
A number of grooves are formed on the side surface of the soundproofing material,
The soundproof material, wherein a depth of the groove formed in the sound insulation improving portion is shallower than a depth of the groove formed in another portion. The soundproof material according to any one of claims 1 to 4,
The soundproof material is formed so as to close a door hole formed in the door of the automobile and is attached to the door,
The soundproofing material, wherein the sound insulation improving part is provided so as to be disposed on the belt line part side of the door.

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