Soundproof material for vehicle

Abstract

This soundproof material (1) for a vehicle comprises a polyurethane foam (10). The polyurethane foam (10) has body parts (20a, 20b, 20c) and high-rigidity parts (21a, 21b) that are continuous with the body parts (20a, 20b, 20c) in the surface direction. The thickness of the high-rigidity parts (21a, 21b) is smaller than the thickness of the body parts (20a, 20b, 20c). The tensile strength of the high-rigidity parts (21a, 21b) is greater than the tensile strength of the body parts (20a, 20b, 20c) and is 1190-3420 kPa.

Description

Soundproofing material for vehicles

[0001] The present disclosure relates to a soundproofing material for vehicles used in engine rooms and the like of vehicles.

[0002] In vehicles such as automobiles, various countermeasures are implemented to reduce noise leaking to the outside and interior of the vehicle. For example, in the engine room of a vehicle, soundproofing materials such as an engine cover, a side cover, and an oil pan cover are arranged around the engine in order to reduce noise radiated from the engine, which is a noise source. This type of soundproofing material, as described for example in Patent Document 1, is composed of a hard cover member made of resin or the like, and a flexible polyurethane foam arranged on the back side of the cover member, and is attached to a mating member (noise source) by, for example, bolting the cover member.

[0003] Japanese Patent Application Laid-Open No. 2004-44526 Japanese Patent Application Laid-Open No. 2020-185967

[0004] In general, flexible polyurethane foam has high air permeability and sound absorption properties, but has low rigidity and thus poor self-supporting properties. For this reason, in consideration of ease of attachment to a mating member and the like, it is used together with a hard cover member having high rigidity. However, the use of a cover member increases the mass and raises the cost accordingly. In addition, the increase in thickness makes application to narrow spaces difficult. In the engine room of a vehicle, not only noise radiated from the noise source but also sound reverberating in the space is a target for reduction. However, when the cover member is arranged on the vehicle compartment side, sound absorbency against reverberant sound from the vehicle compartment side decreases.

[0005] On the other hand, the shapes of mating members to which soundproofing materials are attached vary, including curved surfaces and uneven surfaces. Soundproofing materials are required to be able to be attached as closely as possible to the shape of the mating member and to exhibit the desired soundproofing performance. For example, Patent Document 2 describes a resin molded product comprising two panels and an integral hinge that connects the panels and is thinner than the panels, in which a hinge reinforcement region with a higher density than the panels is placed on the integral hinge to improve the strength of the integral hinge. However, Patent Document 2 describes increasing the strength of the hinge portion that is used when bent, and does not consider the ease of attachment to the mating member. Furthermore, the resin molded product described in Patent Document 2 is a vehicle exterior component such as a side mudguard, and is not made of polyurethane foam, nor is soundproofing considered.

[0006] This disclosure is made in view of the above circumstances and aims to provide a soundproofing material for vehicles that can be used on its own and has excellent attachability to mating components, comprising polyurethane foam.

[0007] (1) The soundproofing material for vehicles according to the present disclosure is a soundproofing material for vehicles comprising polyurethane foam, wherein the polyurethane foam has a main body and a high-rigidity portion continuous in the planar direction with respect to the main body, wherein the thickness of the high-rigidity portion is less than the thickness of the main body and the tensile strength is greater than the tensile strength of the main body and is 1190 kPa or more and 3420 kPa or less.

[0008] The polyurethane foam constituting the soundproofing material for vehicles disclosed herein (hereinafter sometimes referred to as "the polyurethane foam of this disclosure") has a high-rigidity portion with greater tensile strength than the main body. Because the high-rigidity portion can be used to attach the material to a mating member, such as by engaging it with the mounting portion of the mating member, the polyurethane foam of this disclosure can be used alone without support from a rigid cover member. Furthermore, the high-rigidity portion is thinner than the main body, making it easier to bend, and its high tensile strength makes it less susceptible to damage when bent or stretched. Therefore, with the polyurethane foam of this disclosure, the soundproofing material for vehicles can be attached to conform to the shape of the mating member by utilizing the high-rigidity portion, and can be placed even in narrow spaces. Thus, the polyurethane foam of this disclosure improves conformability to the shape of the mating member and allows attachment to areas that could not be covered due to space constraints, thereby increasing the coverage rate of the mating member. As a result, the soundproofing effect of the soundproofing material for vehicles disclosed can be further enhanced.

[0009] As mentioned above, in a vehicle's engine compartment, not only radiated noise from noise sources but also reverberating noise within the space needs to be reduced. When the polyurethane foam of this disclosure is used alone, sound absorption is exhibited on both sides of the polyurethane foam (the side facing the noise source and the opposite side), thus further improving its effectiveness as a soundproofing material. Furthermore, by not using a rigid cover member, the soundproofing material for vehicles of this disclosure can be made lighter and less expensive, and it can also be fixed to the mating member using a simple method such as clips.

[0010] (2) In the configuration of (1) above, the normal incidence sound absorption coefficient of the main body may be 0.30 or more at a frequency of 800 Hz and 0.50 or more at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm and a thickness of 10 mm.

[0011] The normal incidence sound absorption coefficient is an indicator of sound absorption, and a higher normal incidence sound absorption coefficient indicates higher sound absorption. In electric vehicles, which have become increasingly popular in recent years, sound absorption in the high-frequency range of around 5000 Hz generated by motors and other components is required. With this configuration, the sound absorption of the main body can be improved in both the low-frequency range including 800 Hz and the high-frequency range including 5000 Hz.

[0012] (3) In the configuration of (1) above, the thickness of the main body may be 5 mm or more and 17.5 mm or less, the tensile strength of the main body may be 700 kPa or more and 1480 kPa or less, and the normal incidence sound absorption coefficient of the main body may be 0.34 or more at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm.

[0013] In this configuration, the tensile strength of the main body is relatively high, and the desired rigidity can be achieved with the polyurethane foam alone. Therefore, the polyurethane foam in this configuration is self-supporting and easy to use on its own. In addition, because the thickness of the main body is relatively small in this configuration, it is easy to apply to narrow spaces. Furthermore, with this configuration, it is possible to enhance the sound absorption in the high-frequency range of the main body, thereby achieving a balance between rigidity and sound absorption.

[0014] (4) In the configuration of (3) above, the normal incidence sound absorption coefficient of the main body at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 0.14 or higher.

[0015] Increasing the thickness of the polyurethane foam might improve sound absorption in the low-frequency range of around 800-1000 Hz. However, in this configuration, sound absorption in the low-frequency range is enhanced while keeping the thickness of the main body relatively small. With this configuration, sound absorption of the main body can be enhanced in both the low-frequency and high-frequency ranges.

[0016] (5) In the configuration of (3) or (4) above, the normal incidence transmission loss of the main body at a frequency of 5000 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 23.00 dB or more.

[0017] Normal incidence transmission loss is an indicator of sound insulation; a higher normal incidence transmission loss indicates higher sound insulation. In this configuration, the sound insulation in the high-frequency range of the main body is relatively high. Therefore, high sound absorption and sound insulation can be achieved in the high-frequency range.

[0018] (6) In any of the configurations described in (3) to (5) above, the normal incidence transmission loss of the main body at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 14.82 dB or more. This configuration makes it possible to improve the sound insulation in the low-frequency range of the main body.

[0019] (7) In any of the above configurations, the thickness of the high-rigidity part may be 1 mm or more and 5 mm or less.

[0020] With this configuration, the thickness of the high-rigidity section is relatively small, making it easier to apply to narrow spaces. This improves conformability to the mating member and ease of installation, and increases the coverage rate of the mating member. As a result, the sound insulation effect of the vehicle sound insulation material disclosed herein can be further enhanced.

[0021] (8) In the configuration of (7) above, the normal incidence sound absorption coefficient of the high-rigidity part may be set to be 0.22 or higher at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm. With this configuration, the sound absorption in the high-frequency range of the high-rigidity part is relatively high. Therefore, the decrease in sound absorption in the high-frequency range can be suppressed in the high-rigidity part, which is mainly used to improve the ease of attachment to the mating member. Furthermore, by combining this configuration with the configuration of (2) or (3) above, the sound absorption in the high-frequency range can be improved not only in the main body but also in the high-rigidity part. This makes it possible to improve the sound absorption of the entire polyurethane foam.

[0022] (9) In the configuration of (7) or (8) above, the normal incidence sound absorption coefficient of the high-rigidity part at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 0.07 or higher. With this configuration, the sound absorption in the low-frequency range of the high-rigidity part is relatively high. Therefore, the decrease in sound absorption in the low-frequency range of the high-rigidity part can be suppressed. Furthermore, by combining this configuration with the configuration of (8) above, the sound absorption of the high-rigidity part can be improved in both the low-frequency and high-frequency ranges.

[0023] (10) In any of the configurations (7) to (9) above, the normal incidence transmission loss of the high-rigidity part at a frequency of 5000 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 22.32 dB or more. In this configuration, the sound insulation performance in the high-frequency range of the high-rigidity part is relatively high. Therefore, the decrease in sound insulation performance in the high-frequency range of the high-rigidity part can be suppressed. Furthermore, by combining this configuration with the configuration of (8) above, high sound absorption and sound insulation performance in the high-frequency range can be achieved.

[0024] (11) In any of the configurations described in (7) to (10) above, the normal incidence transmission loss of the high-rigidity part at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, may be 12.29 dB or more. This configuration makes it possible to improve the sound insulation in the low-frequency range of the high-rigidity part.

[0025] (12) In any of the above configurations, the polyurethane foam may have a plurality of main body portions, and the high-rigidity portion may be arranged between adjacent main body portions. With this configuration, for example, the high-rigidity portion can be engaged with the mounting portion of the mating member, or the polyurethane foam can be bent starting from the high-rigidity portion, thereby improving the ease of attachment to the mating member.

[0026] (13) In the configuration of (12) above, the high-rigidity part is a hinge part that connects a pair of adjacent main body parts, and the polyurethane foam may be configured to be attached to the mating member by curving the hinge part. With this configuration, it is easy to attach the soundproofing material for vehicles so as to conform to the shape of the mating member. As a result, the coverage rate on the mating member can be increased, and the soundproofing effect can be enhanced.

[0027] (14) In any of the configurations (1) to (12) above, the high-rigidity part may have a recess surrounded by the main body. With this configuration, even if the mating member has a protrusion, the ability to conform to the shape of the mating member can be improved by engaging the recess (high-rigidity part) with it. Also, if the protrusion of the mating member is a mounting part, the soundproofing material for vehicles can be easily fixed by engaging the recess with it.

[0028] (15) In the configuration of (14) above, the recess may be configured to engage with the protrusion of the mating member. This configuration improves the ability to conform to the shape of the mating member and improves the sound insulation effect. In addition, if the sound insulation material for vehicles can be fixed by engagement with the protrusion, the ease of installation is improved.

[0029] (16) In any of the configurations described in (12) to (15) above, the polyurethane foam may have a configuration having a plurality of high-rigidity parts. With this configuration, by appropriately arranging the high-rigidity parts according to the mating member, the conformability to the mating member, ease of attachment, etc. can be improved.

[0030] The soundproofing material for vehicles disclosed herein can be used on its own and offers excellent attachment to mating components. The soundproofing material for vehicles disclosed herein allows for increased coverage of mating components, thereby improving the soundproofing effect.

[0031] This is a top view of the soundproofing material for vehicles according to the first embodiment. This is a cross-sectional view taken along line II-II in Figure 1. This is a graph of the normal incidence sound absorption coefficient for samples 1 to 3. This is a graph of the normal incidence sound absorption coefficient for samples 4 to 6. This is a graph of the normal incidence sound absorption coefficient for samples 7 to 9 and 13. This is a graph of the normal incidence sound absorption coefficient for samples 10 to 12. This is a graph of the normal incidence transmission loss for samples 1 to 3. This is a graph of the normal incidence transmission loss for samples 4 to 6. This is a graph of the normal incidence transmission loss for samples 7 to 9 and 13. This is a graph of the normal incidence transmission loss for samples 10 to 12. This is a perspective view of the soundproofing material for vehicles according to the second embodiment. This is an unfolded view of the same soundproofing material for vehicles.

[0032] The embodiments of the soundproofing material for vehicles described herein will be described below. However, the embodiments are not limited to those described below, and can be implemented in various modified and improved forms as possible for those skilled in the art. In this specification, numerical ranges using "~" indicate a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the individually described upper and lower limits can be combined arbitrarily. Furthermore, the upper and lower limits of the numerical ranges can be replaced with the values ​​shown in the examples.

[0033] <First Embodiment> [Configuration] The configuration of the first embodiment of the soundproofing material for vehicles of the present disclosure will be described. Figure 1 shows a top view of the soundproofing material for vehicles of this embodiment. Figure 2 shows a cross-sectional view taken along line II-II of Figure 1. In Figure 1, for the sake of explanation, the thin-walled high-rigidity section is shown by a dashed line. As shown in Figures 1 and 2, the soundproofing material for vehicles 1 consists of polyurethane foam 10. The polyurethane foam 10 has three main body sections 20a, 20b, and 20c, two first high-rigidity sections 21a and 21b, and four second high-rigidity sections 22a, 22b, 22c, and 22d.

[0034] The main body sections 20a, 20b, and 20c are rectangular plates of the same size and are arranged to divide the polyurethane foam 10 into three parts in the longitudinal direction via the first high-rigidity sections 21a and 21b. The thickness of the main body sections 20a, 20b, and 20c is 10 mm. The tensile strength of the main body sections 20a, 20b, and 20c is 1038 kPa each. The first high-rigidity section 21a is arranged in a strip shape in the short direction between the main body sections 20a and 20b. The first high-rigidity section 21b is arranged in a strip shape in the short direction between the main body sections 20b and 20c. The thickness of the first high-rigidity sections 21a and 21b is 2.5 mm each, which is thinner than the main body sections 20a, 20b, and 20c. The tensile strength of the first high-rigidity sections 21a and 21b is 2794 kPa each, which is greater than that of the main body sections 20a, 20b, and 20c. The first high-rigidity sections 21a and 21b are hinge sections that connect adjacent pairs of main body sections. As shown by the white arrows in Figure 2, the polyurethane foam 10 (vehicle soundproofing material 1) is mounted on a mating member (noise source) (not shown) by curving the first high-rigidity sections (hinge sections) 21a and 21b to erect the main body sections 20a and 20c.

[0035] The second high-rigidity sections 22a and 22b both have circular openings and are arranged as recesses surrounded by the main body section 20a. The second high-rigidity sections 22a and 22b are spaced apart in the short direction. The second high-rigidity sections 22a and 22b are the same size. The thickness of the second high-rigidity sections 22a and 22b (thickness from the bottom surface of the polyurethane foam 10) is 5 mm, which is thinner than the main body section 20a that is continuous with them. The tensile strength of the second high-rigidity sections 22a and 22b is greater than that of the main body section 20a, at 1476 kPa. The second high-rigidity sections 22c and 22d are the same as the second high-rigidity sections 22a and 22b, except that their location is within the main body section 20c. The second high-rigidity sections 22a, 22b, 22c, and 22d engage with protrusions arranged on the mating member.

[0036] [Effects] The vehicle soundproofing material 1 of this embodiment is attached to conform to the shape of the mating member by utilizing the first high-rigidity parts 21a and 21b as hinge parts. In addition, the second high-rigidity parts 22a, 22b, 22c, and 22d engage with the protrusions of the mating member. This improves the ability to conform to the shape of the mating member and increases the coverage rate. As a result, the soundproofing effect of the vehicle soundproofing material 1 can be fully demonstrated. In this embodiment, the main body part 20b has a protruding part 23. The protruding part 23 is located in the center of the upper surface of the main body part 20b and engages with the recess of the mating member. In this way, by not only arranging high-rigidity parts in the polyurethane foam 10 but also forming the main body part to conform to the shape of the mating member, the conformability can be further improved.

[0037] <Second Embodiment> [Configuration] The configuration of the second embodiment of the soundproofing material for vehicles of the present disclosure will be described. Figure 11 shows a perspective view of the soundproofing material for vehicles of this embodiment. Figure 12 shows an unfolded view of the soundproofing material for vehicles. In Figure 12, for the sake of explanation, the thin-walled, high-rigidity portion is shown by a dashed line. As shown in Figures 11 and 12, the soundproofing material for vehicles 3 has a rectangular box shape and covers the entire mating member (noise source) which is not shown. The soundproofing material for vehicles 3 is made of polyurethane foam 30. The polyurethane foam 30 has eleven main body portions 40a to 40k and a high-rigidity portion 41 arranged between adjacent main body portions.

[0038] The main body sections 40a to 40g constitute the six faces of a rectangular parallelepiped. Of these, the main body section 40a, which constitutes the upper part of the front surface of the rectangular parallelepiped, has a rectangular parallelepiped-shaped locking projection 42 that protrudes inward. The main body section 40e, which constitutes the lower part of the front surface of the rectangular parallelepiped, has a locking hole 430 into which the locking projection 42 is inserted. The main body section 40a and the main body section 40e are fixed together by the insertion of the locking projection 42 into the locking hole 430. Furthermore, the main body section 40j is connected to the left side of the main body section 40e, with the high-rigidity section 41 in between, and the main body section 40k is connected to the right side, with the high-rigidity section 41 in between. Both the main body sections 40j and 40k are in the same small piece shape and are inserted into locking holes 431 and 432, respectively, which will be described later. The main body section 40f, which constitutes the left face of the rectangular parallelepiped, has the main body section 40h positioned to the left of the high-rigidity section 41. The main body portion 40h has a locking hole portion 431. The main body portion 40h is bent when attached to the mating member, and the main body portion 40j is inserted through the locking hole portion 431. Similarly, the main body portion 40g, which constitutes the right side of the rectangular parallelepiped, has a main body portion 40i positioned to the right of the high-rigidity portion 41. The main body portion 40i has a locking hole portion 432. The main body portion 40i is bent when attached to the mating member, and the main body portion 40k is inserted through the locking hole portion 432.

[0039] The thickness of the main body sections 40a to 40k is 12.5 mm. The tensile strength of the main body sections 40a to 40k is 1065 kPa. Furthermore, when measured using a disc-shaped sample with a diameter of 30 mm, the normal incidence sound absorption coefficient of the main body sections 40a to 40k is 0.14 or higher at a frequency of 800 Hz, and 0.34 or higher at a frequency of 5000 Hz. The normal incidence transmission loss at a frequency of 800 Hz is 14.82 dB or higher, and the normal incidence transmission loss at a frequency of 5000 Hz is 23.00 dB or higher.

[0040] The high-rigidity section 41 is arranged in a strip shape between adjacent main body sections. The high-rigidity section 41 is a hinge section that connects adjacent main body sections. The thickness of the high-rigidity section 41 is 2.5 mm, which is thinner than that of the main body sections 40a to 40k. The tensile strength of the high-rigidity section 41 is 1584 kPa, which is greater than that of the main body sections 40a to 40k. Furthermore, when measured using a disc-shaped sample with a diameter of 30 mm, the normal incidence sound absorption coefficient of the high-rigidity section 41 at a frequency of 800 Hz is 0.07 or more, and at a frequency of 5000 Hz it is 0.22 or more. The normal incidence transmission loss at a frequency of 800 Hz is 12.29 dB or more, and at a frequency of 5000 Hz it is 22.32 dB or more.

[0041] After the polyurethane foam 30 is foam-molded into the unfolded shape shown in Figure 12, it is assembled into a box shape to cover the entire mating member (noise source). For example, the mating member is placed on the main body portion 40d, and the remaining main body portions 40a to 40c and 40e to 40k are bent inward by approximately 90° (valley fold) around the high-rigidity portion (hinge portion) 41 as the axis, the small pieces of main body portions 40j and 40k are inserted through the locking holes 431 and 432, and the locking projection 42 is inserted into the locking hole 430.

[0042] [Effects and Effects] The soundproofing material 3 for vehicles of this embodiment has the same effects and effects as the soundproofing material 1 for vehicles of the first embodiment in respect of the parts that share the same structure. With the soundproofing material 3 for vehicles, the polyurethane foam 30 is integrally foam-molded into an unfolded shape, and the high-rigidity part 41, which serves as a hinge, can be easily assembled into a box shape. At this time, the main body parts 40j and 40k are inserted through the locking holes 431 and 432, and the locking projection 42 is inserted into the locking hole 430, which is a simple method of attachment to the mating member. As a result, the entire mating member is housed inside the soundproofing material 3 for vehicles, which further enhances the soundproofing effect.

[0043] The thickness of the high-rigidity portion 41 is smaller than the thickness of the main body portions 40a to 40k, and the tensile strength of the high-rigidity portion 41 is greater than the tensile strength of the main body portions 40a to 40k. Therefore, when assembling from a developed shape into a three-dimensional shape, it is easy to bend with the high-rigidity portion 41 as an axis, and the high-rigidity portion 41 is less likely to be damaged. Further, the tensile strength of the main body portions 40a to 40k is 1065 kPa, which is relatively large. Therefore, the desired rigidity can be achieved by the polyurethane foam 30 alone, and the soundproofing material 3 for vehicles can be configured. Thereby, sound absorption performance is exhibited on both the front and back surfaces of the polyurethane foam 30 (the outer surface and the surface on the mating member side), and not only the sound radiated from the mating member but also the sound reverberating in the space can be reduced. In addition, the thickness of the main body portions 40a to 40k is 12.5 mm, which is relatively small, so it is easy to apply to narrow spaces. Further, since not only the main body portions 40a to 40k but also the high-rigidity portion 41 have high sound absorption and sound insulation properties, the soundproofing effect of the vehicle soundproofing material 3 is high.

[0044] <Other Embodiments> In the vehicle soundproofing material of the present disclosure, configurations other than polyurethane foam are not particularly limited. The vehicle soundproofing material of the present disclosure may be composed of only polyurethane foam as in the first and second embodiments described above, or may be composed by combining polyurethane foam with other members. For example, when the vehicle soundproofing material of the present disclosure is embodied as an engine cover, the engine cover may have a single-layer structure of polyurethane foam, or may have a multi-layer structure including a soundproofing layer made of polyurethane foam and a skin layer covering the soundproofing layer. The skin layer may be formed using resin, elastomer, metal, fiber, or the like. In addition, "vehicles" as the application includes not only automobiles but also airplanes, trains, and the like. Hereinafter, the polyurethane foam constituting the vehicle soundproofing material of the present disclosure will be described.

[0045] [Configuration of Polyurethane Foam] The polyurethane foam comprises a main body portion and a high-rigidity portion continuously connected to the main body portion in the planar direction.

[0046] (1) Main body portion The main body portion primarily contributes to sound insulation. The main body portion may be a single continuous member, or may be a plurality of members divided by high-rigidity portions. The thickness of the main body portion may be appropriately adjusted depending on the application. The thickness of the main body portion may be constant or may vary, for example, due to the formation of irregularities. For example, from the viewpoint that when the thickness is relatively small, it is easy to apply to narrow spaces in vehicles, the thickness of the main body portion is preferably 5 mm or more and 17.5 mm or less. Further, from the viewpoint of increasing rigidity to impart self-supporting properties, the tensile strength of the main body portion is preferably 700 kPa or more, more preferably 800 kPa or more. On the other hand, in consideration of sound absorption, the tensile strength of the main body portion is preferably 1480 kPa or less, more preferably 1200 kPa or less. The tensile strength in the present disclosure is the tensile strength at break (TS ｂ ) measured by a tensile test in accordance with JIS K6251:2023. A dumbbell-shaped No. 1 test piece shall be used as the test piece.

[0047] The following two examples are given of the normal incidence sound absorption coefficient, which is an index of the sound absorption property of the main body portion. In the present disclosure, the value measured by the method described in JIS A1405-2:2007 is employed as the normal incidence sound absorption coefficient.

[0048] (A) First Example When the normal incidence sound absorption coefficient is measured using a disk-shaped sample having a diameter of 30 mm and a thickness of 10 mm, it is 0.30 or more at a frequency of 800 Hz and 0.50 or more at a frequency of 5000 Hz. In the case of the first example, it is desirable that the values of the normal incidence sound absorption coefficient at 800 Hz and 5000 Hz are 0.30 or more and 0.50 or more, respectively, but an embodiment that satisfies only one of them is also acceptable. Further, it is more preferable that the normal incidence sound absorption coefficient is 0.30 or more in the frequency range of 800 to 5000 Hz, and also in the frequency range exceeding 5000 Hz up to 6300 Hz.

[0049] (B) In the second example, when the thickness of the main body is 5 mm or more and 17.5 mm or less, the normal incidence sound absorption coefficient is measured using a disc-shaped sample with a diameter of 30 mm and is 0.14 or more at a frequency of 800 Hz and 0.34 or more at a frequency of 5000 Hz. In the second example, the thickness of the disc-shaped sample is the same as the thickness of the main body to be measured. In the second example, it is desirable that the normal incidence sound absorption coefficients at 800 Hz and 5000 Hz are 0.14 or more and 0.34 or more, respectively, but it is also acceptable to satisfy only one of them. Furthermore, it is more preferable that the normal incidence sound absorption coefficient is 0.14 or more in the frequency range of 800 to 5000 Hz. Furthermore, it is more preferable that the normal incidence sound absorption coefficient is 0.34 or more in the frequency range of 5000 Hz to 6300 Hz.

[0050] In the second example, it is desirable that the normal incidence transmission loss, an indicator of sound insulation, be 14.82 dB or higher at a frequency of 800 Hz and 23.00 dB or higher at a frequency of 5000 Hz, when measured using a disc-shaped sample with a diameter of 30 mm. In this disclosure, the normal incidence transmission loss is the value measured by the method described in ASTM E 2611. The thickness of the disc-shaped sample used is the same as the thickness of the main body to be measured. It is desirable that the normal incidence transmission loss is 14.82 dB or higher and 23.00 dB or higher at 800 Hz and 5000 Hz, respectively, but it is also acceptable to satisfy only one of them. Furthermore, it is more preferable that the normal incidence transmission loss is 14.82 dB or higher in the frequency range of 800 to 5000 Hz. Furthermore, it is more preferable that the normal incidence transmission loss is 23.00 dB or higher in the frequency range of 5000 Hz to 6300 Hz.

[0051] (2) High-rigidity part The high-rigidity part may be one or more, and its shape, size, arrangement, etc., are not particularly limited. For example, as in the first and second embodiments described above, multiple main body parts may be connected via the high-rigidity part. In this configuration, by using the high-rigidity part as a hinge part, the main body parts to be connected can be arranged to conform to the shape of the mating member. Alternatively, it may be formed as a recess within the main body part. In this configuration, the high-rigidity part can be engaged with a protrusion on the mating member to improve its conformability to the shape of the mating member. Furthermore, if the protrusion on the mating member is a mounting part, it becomes easier to fix the soundproofing material for vehicles.

[0052] The thickness of the high-rigidity section is smaller than the thickness of the main body. More specifically, the thickness of the high-rigidity section should be smaller than the thickness of the adjacent main body section. The thickness of the high-rigidity section should be between 1 mm and 5 mm from the viewpoint of being easy to apply to the narrow space of a vehicle and easy to deform. In addition, the tensile strength should be greater than the tensile strength of the main body, between 1190 kPa and 3420 kPa.

[0053] To enhance the sound insulation properties of polyurethane foam, it is desirable that sound insulation properties be exhibited even in the high-rigidity section. For example, when the thickness of the high-rigidity section is 1 mm or more and 5 mm or less, it is desirable that the normal incidence sound absorption coefficient, when measured using a disc-shaped sample with a diameter of 30 mm, be 0.07 or more at a frequency of 800 Hz and 0.22 or more at a frequency of 5000 Hz. Here, the thickness of the disc-shaped sample used should be the same as the thickness of the high-rigidity section being measured. While it is desirable that the normal incidence sound absorption coefficient values ​​at 800 Hz and 5000 Hz be 0.07 or more and 0.22 or more, respectively, a configuration that satisfies only one of these conditions is also acceptable. Furthermore, it is more preferable that the normal incidence sound absorption coefficient is 0.07 or more in the frequency range of 800 to 5000 Hz. Furthermore, it is more preferable that the normal incidence sound absorption coefficient is 0.22 or more in the frequency range of 5000 Hz to 6300 Hz.

[0054] Furthermore, when the thickness of the high-rigidity section is 1 mm or more and 5 mm or less, it is desirable that the normal incidence transmission loss, when measured using a disc-shaped sample with a diameter of 30 mm, be 12.29 dB or more at a frequency of 800 Hz and 22.32 dB or more at a frequency of 5000 Hz. It is desirable that the normal incidence transmission loss values ​​at 800 Hz and 5000 Hz are 12.29 dB or more and 22.32 dB or more, respectively, but it is also acceptable to satisfy only one of them. Moreover, it is more preferable that the normal incidence transmission loss is 12.29 dB or more in the frequency range of 800 to 5000 Hz. Furthermore, it is more preferable that the normal incidence transmission loss is 22.32 dB or more in the frequency range of 5000 Hz to 6300 Hz.

[0055] [Method for Manufacturing Polyurethane Foam] The polyurethane foam of this disclosure can be manufactured by foam molding a foamed urethane resin raw material composed of an isocyanate component, a polyol component, a catalyst, a blowing agent, etc. For example, by compressing the foamed urethane resin raw material in the front-to-back direction before the curing reaction is completed, the thickness and tensile strength can be adjusted. This allows for adjustment of sound insulation performance. Furthermore, by compressing the foamed urethane resin raw material in the front-to-back direction before the curing reaction is completed, an intermediate layer is formed between the surface layer, which includes the front surface, and the back layer, which includes the back surface, making it easier to achieve desired rigidity and sound absorption. Here, in order to manufacture a thin-walled, high-rigidity section with relatively high tensile strength, it is advisable to increase the compression ratio [(thickness before compression - thickness after compression) / thickness before compression × 100]. In addition, the cell structure of the surface and back layers may be adjusted by crushing with a roll or the like after foam molding to achieve desired sound insulation performance.

[0056] The isocyanate component is not particularly limited as long as it forms a urethane bond through reaction with the polyol component. For example, it can be appropriately selected from tolylene diisocyanate (TDI), phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate (MDI), triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, naphthalene diisocyanate (NDI), and their derivatives. Examples of derivatives include prepolymers obtained by the reaction of isocyanate and polyol, modified polyisocyanates, and polymeric MDI (multinuclear) having three or more isocyanate groups and benzene rings in one molecule.

[0057] The polyol component can be appropriately selected from among polyhydric hydroxy compounds, polyether polyols, polyester polyols, polymer polyols, polyether polyamines, polyester polyamines, alkylene polyols, urea-dispersed polyols, melamine-modified polyols, polycarbonate polyols, acrylic polyols, polybutadiene polyols, phenol-modified polyols, and others.

[0058] Examples of catalysts include amine catalysts such as tetraethylenediamine, triethylenediamine, and dimethylethanolamine, as well as organometallic catalysts such as tin laurate and tin octanoate. Examples of blowing agents include water, methylene chloride, chlorofluorocarbons, and CO2. ２ Examples include gas.

[0059] The foamed urethane resin raw material may further contain foam stabilizers, plasticizers, crosslinking agents, chain extenders, flame retardants, antistatic agents, viscosity reducers, stabilizers, fillers, colorants, etc. Examples of foam stabilizers include silicone-based foam stabilizers. Examples of crosslinking agents include diethylene glycol, triethanolamine, and diethanolamine. Examples of flame retardants include expanded graphite, phosphorus-based, halogen-based, and metal hydroxide-based flame retardants.

[0060] The foamed urethane resin raw material is preferably prepared by adding the isocyanate component to a premixed polyol, which is made by pre-mixing components other than the isocyanate component with the polyol component. In this case, the premixed polyol and the isocyanate component may be mechanically stirred using a propeller or the like, or they may be mixed by discharging the premixed polyol and the isocyanate component separately at high pressure using a high-pressure injector or the like, causing the two components to collide. It is desirable that the premixed polyol and the isocyanate component be blended so that the isocyanate index (equivalents of isocyanate groups / equivalents of active hydrogen groups × 100) is between 100 and 150, preferably between 100 and 120.

[0061] Next, the present disclosure will be described in more detail with reference to examples.

[0062] <Manufacturing of Polyurethane Foam> [Manufacturing Example A] First, 70 parts by mass of polyether polyol (AGC Inc.'s "Exenol® 837") and 30 parts by mass of polymer polyol (Sanyo Chemical Industries, Ltd.'s "Sannix® KC-900") were added as polyol components, 1 part by mass of diethanolamine as a crosslinking agent, 3 parts by mass of water as a blowing agent, 0.3 parts by mass of amine catalyst A (EVONIK's "DABCO® 33LV"), and 0.1 parts by mass of amine catalyst B (MOMENTIVE's "Niax® Catalyst A-1") were added and mixed to prepare a premix polyol. Next, the prepared premixed polyol and polymeric MDI (BASF INOAC Polyurethane Co., Ltd.'s "Luplanate® M20S") as an isocyanate component were mixed to achieve an isocyanate index of 100, thereby preparing a foamed urethane resin raw material.

[0063] Next, a wax-based water-based release agent was applied to the mold surface of the mold, which had been pre-adjusted to 50°C. The foamed polyurethane resin raw material was then injected into rectangular cavities (500 mm long, 600 mm wide, with four thicknesses: 20 mm, 15 mm, 10 mm, and 5 mm), sealed, and maintained for 1 minute. After that, the mold was opened, a plate (500 mm long, 600 mm wide) was placed on top of the partially cured foamed polyurethane resin raw material, the mold was clamped again, and maintained for another 3 minutes. At this time, the compression ratio was adjusted by changing the thickness of the plate used. The foam curing reaction was completed while the material was compressed by the plate, and a polyurethane foam was produced having a surface layer including the top surface, a back layer including the bottom surface, and an intermediate layer placed between them. The obtained polyurethane foam was passed between a pair of rolls, and both the top and bottom surfaces were roll-crushed. In this way, twelve samples of polyurethane foam with different thicknesses and compression ratios were produced. Hereinafter, the produced polyurethane foams will be referred to as Samples 1 to 12. The thickness and compression ratio of each sample are summarized in Table 1 below. In Table 1, the thickness before compression is the same as the thickness of the mold cavity.

[0064] [Manufacturing Example B] A sample of polyurethane foam was manufactured in the same manner as in Manufacturing Example A, except that a mold with a cavity thickness of 10 mm was used and compression was not performed using a plate during foam molding. The foamed polyurethane resin raw material was held in the mold for 5 minutes. The manufactured polyurethane foam is referred to as Sample 13.

[0065]

[0066] <Evaluation of Polyurethane Foam> The tensile strength, density, normal incidence sound absorption coefficient, and normal incidence transmission loss of the manufactured samples were measured to evaluate their rigidity and sound absorption properties.

[0067] [Measurement Method] (1) Tensile Strength A tensile test was performed on each sample in accordance with JIS K6251:2023, and the tensile strength at break (TS) was measured. ｂ The following measurements were taken: A dumbbell-shaped specimen (Type 1) was used, and the tensile speed was set to 200 mm / min.

[0068] (2) Density: The density of each sample was calculated by dividing its mass by its volume.

[0069] (3) Normal incidence sound absorption coefficient: The normal incidence sound absorption coefficient was measured using a 30 mm diameter disc-shaped sample cut from each sample, according to the method described in JIS A1405-2:2007. The thickness of the disc-shaped sample was the same as the thickness of the manufactured sample.

[0070] (4) Normal incidence transmission loss A 30 mm diameter disc-shaped sample was cut from each sample, and the normal incidence transmission loss was measured using the method described in ASTM E 2611. The thickness of the disc-shaped sample was the same as the thickness of the manufactured sample.

[0071] [Measurement Results] Table 1, shown above, summarizes the tensile strength and density of samples 1 to 13. Samples 1 to 13 are classified by their thickness before compression, and Figures 3 to 6 show graphs of the normal incidence sound absorption coefficient against frequency for each sample. Figure 3 shows the graphs for samples 1 to 3, Figure 4 shows the graphs for samples 4 to 6, Figure 5 shows the graphs for samples 7 to 9 and 13, and Figure 6 shows the graphs for samples 10 to 12. Similarly, Figures 7 to 10 show graphs of the normal incidence transmission loss against frequency for each sample. Figure 7 shows the graphs for samples 1 to 3, Figure 8 shows the graphs for samples 4 to 6, Figure 9 shows the graphs for samples 7 to 9 and 13, and Figure 10 shows the graphs for samples 10 to 12.

[0072] As shown in Table 1, samples 1 to 8, with a thickness of 5 mm to 17.5 mm, had a tensile strength of 708 kPa to 1476 kPa, indicating sufficient rigidity to be self-supporting. Furthermore, as shown in Figures 3 to 5, all samples had a normal incidence sound absorption coefficient of 0.14 or higher at 800 Hz and a normal incidence sound absorption coefficient of 0.34 or higher at 5000 Hz, confirming high sound absorption in both low and high frequency ranges. In addition, as shown in Figures 7 to 9, all samples had a normal incidence transmission loss of 14.82 dB or higher at 800 Hz and a normal incidence transmission loss of 23.00 dB or higher at 5000 Hz, confirming high sound insulation in both low and high frequency ranges.

[0073] In sample 13, which had a thickness of 10 mm, the normal incidence sound absorption coefficient at a frequency of 800 Hz was 0.32, and the normal incidence sound absorption coefficient at a frequency of 5000 Hz was 0.52. As shown in Figure 5, it was confirmed that it had high sound absorption in both the low-frequency and high-frequency ranges. On the other hand, the tensile strength was low, and as shown in Figure 9, the sound insulation was poor.

[0074] Based on the above, Samples 1 to 8 are suitable for the main body because they have relatively high rigidity and excellent sound absorption and sound insulation properties. Sample 13 is also suitable for the main body because it has excellent sound absorption properties.

[0075] Samples 8-12, with a thickness of 1 mm to 5 mm, were foam-molded with a compression ratio of 40% or more. As a result, their tensile strength was between 1476 kPa and 3414 kPa, indicating greater rigidity than the other samples. Furthermore, as shown in Figures 5 and 6, the normal incidence sound absorption coefficient at 800 Hz was 0.07 or higher for all samples, and at 5000 Hz it was 0.22 or higher. In addition, as shown in Figures 8 and 9, the normal incidence transmission loss at 800 Hz was 12.29 dB or higher for all samples, and at 5000 Hz it was 22.32 dB or higher for all samples. Therefore, samples 8-12 are suitable as high-rigidity parts due to their relatively small thickness and high rigidity.

[0076] The soundproofing material for vehicles disclosed herein is suitable for use as an eAxle (electric drive module integrating motor, transaxle, and inverter) cover, motor cover, engine cover, timing chain cover, side cover, oil pan cover, inverter cover, compressor cover, dash insulator, floor insulator, rear package tray, wheelhouse liner, and under cover, as well as for use as a soundproofing material placed around the transmission and other components.

[0077] 1: Soundproofing material for vehicles, 10: Polyurethane foam, 20a, 20b, 20c: Main body, 21a, 21b: First high-rigidity part, 22a, 22b, 22c, 22d: Second high-rigidity part, 23: Protruding part, 3: Soundproofing material for vehicles, 30: Polyurethane foam, 40a to 40k: Main body, 41: High-rigidity part, 42: Locking projection, 430, 431, 432: Locking hole.

Claims

1. A soundproofing material for vehicles comprising polyurethane foam, wherein the polyurethane foam has a main body and a high-rigidity portion continuous with the main body in the planar direction, the thickness of the high-rigidity portion being smaller than the thickness of the main body, and the tensile strength being greater than the tensile strength of the main body, being 1190 kPa or more and 3420 kPa or less.

2. The sound-absorbing material for vehicles according to claim 1, wherein the normal incidence sound absorption coefficient of the main body is 0.30 or more at a frequency of 800 Hz and 0.50 or more at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm and a thickness of 10 mm.

3. The soundproofing material for vehicles according to claim 1, wherein the thickness of the main body is 5 mm or more and 17.5 mm or less, the tensile strength of the main body is 700 kPa or more and 1480 kPa or less, and the normal incidence sound absorption coefficient of the main body is 0.34 or more at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm.

4. The soundproofing material for vehicles according to claim 3, wherein the normal incidence sound absorption coefficient of the main body at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, is 0.14 or more.

5. The soundproofing material for vehicles according to claim 3, wherein the normal incidence transmission loss of the main body at a frequency of 5000 Hz, measured using a disc-shaped sample with a diameter of 30 mm, is 23.00 dB or more.

6. The soundproofing material for vehicles according to claim 5, wherein the normal incidence transmission loss of the main body at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, is 14.82 dB or more.

7. The soundproofing material for vehicles according to claim 1, wherein the thickness of the high-rigidity portion is 1 mm or more and 5 mm or less.

8. The soundproofing material for vehicles according to claim 7, wherein the normal incidence sound absorption coefficient of the high-rigidity part is 0.22 or more at a frequency of 5000 Hz when measured using a disc-shaped sample with a diameter of 30 mm.

9. The soundproofing material for vehicles according to claim 8, wherein the normal incidence sound absorption coefficient of the high-rigidity portion at a frequency of 800 Hz, measured using a disc-shaped sample with a diameter of 30 mm, is 0.07 or more.

10. The soundproofing material for vehicles according to claim 7, wherein the normal incidence transmission loss of the high-rigidity portion at a frequency of 5000 Hz, measured using a disc-shaped sample with a diameter of 30 mm, is 22.32 dB or more.

11. The soundproofing material for vehicles according to claim 10, wherein the normal incidence transmission loss at a frequency of 800 Hz of the high-rigidity portion, measured using a disc-shaped sample with a diameter of 30 mm, is 12.29 dB or more.

12. The soundproofing material for vehicles according to claim 1, wherein the polyurethane foam has a plurality of main body portions, and the high-rigidity portion is arranged between adjacent main body portions.

13. The high-rigidity portion is a hinge portion connecting a pair of adjacent main body portions, and the polyurethane foam is attached to the mating member by curving the hinge portion, as described in claim 12.

14. The soundproofing material for vehicles according to claim 1, wherein the high-rigidity portion has a recess surrounded by the main body portion.

15. The soundproofing material for vehicles according to claim 14, wherein the recess engages with a protrusion on a mating member.

16. The soundproofing material for vehicles according to claim 12 or claim 14, wherein the polyurethane foam has a plurality of the high-rigidity parts.

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