JP2006017983A - Sound insulation member for dashpanel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the man-hours for mounting while maintaining sound insulation performance. <P>SOLUTION: The sound insulation member has a base layer 1 composed of a rigid foamed urethane having an open-cell structure of ≥50% in open cell percentage and having properties of ≥5 N/cm<SP>2</SP>in hardness, 0.03 to 0.15 g/cm<SP>3</SP>in density, 0.5 to 10 mm in cell diameter, and ≥45% in average sound absorption coefficient of sound of 1 to 2 KHz. The base layer 1 has the above characteristics and therefore has a sufficient shape retaining property and excellent sound absorption property as well. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a soundproofing member used for a dash panel of an automobile, and more particularly to a soundproofing member that can prevent noise in an engine room and noise outside the vehicle from entering the vehicle interior and reduce the number of mounting steps.

  In recent years, there has been a demand for improvement in the quietness of an automobile interior, and various means for suppressing the intrusion of noise from an engine room, wind noise, noise from tires, and the like into the passenger compartment have been adopted. For example, as one means for suppressing the propagation of noise from the engine room into the passenger compartment, a dash silencer is arranged along the passenger compartment side surface of the dash panel.

  This dash silencer is formed by laminating a felt layer and a sheet layer made of PVC, for example, and the felt layer is disposed to face the dash panel, and the seat layer is disposed on the vehicle compartment side. The felt layer acts as a sound absorbing layer that absorbs noise, and the sheet layer is laminated as a design layer constituting the design surface.

  However, the felt layer is inferior in the ability to follow the uneven shape of the dash panel, and there is a problem that a gap is generated between the dash panel and the vibration damping performance and sound insulation performance are reduced. Therefore, in recent years, as described in Patent Document 1, a sound absorbing layer is formed by molding from soft foamed urethane on the back surface side of the sheet layer, thereby forming a shape that conforms to the uneven shape of the dash panel. ing.

  By the way, in recent years, automation is also progressing in the assembly process of the dash silencer, and the softness of the dash silencer is becoming a major obstacle to material handling (material handling). In other words, if the sheet layer is soft and the sound absorbing layer made of urethane foam is also soft, the entire dash silencer is soft and not only difficult to carry automatically, but also easily deformed when mounted on the vehicle. This causes a problem that it cannot be mounted with high accuracy. If the sheet layer is replaced with a hard resin plate that also serves as a design layer, the shape can be maintained, so it can be easily transported, and it can be attached with high precision simply by pressing it in one direction toward the dash panel. Since the layer is not soft as in the prior art, the vibration of the dash panel is likely to be transmitted to the hard resin plate through the fixing means, which may cause secondary noise. If a grommet such as rubber is interposed in the fixing means, the problem of secondary noise is solved, but the number of parts increases and the number of assembling steps increases, resulting in an increase in cost. Further, even if a hard resin plate is to be secured to have a thickness sufficient to maintain the shape, the weight of the dash silencer itself increases and the running performance is affected.

  Therefore, it is conceivable to use hard foamed urethane instead of the conventional felt layer or soft foamed urethane from the viewpoints of following the uneven shape of the dash panel, reducing the weight, and maintaining the shape during mounting. If the design layer is soft like a conventional sheet layer, generation of secondary noise is also suppressed. However, general hard foamed urethane has a lower sound absorption characteristic than soft foamed urethane, and is not preferable as a soundproof member for a dash panel in terms of soundproofing function. In Patent Document 1, it is described that a shock absorbing pad made of hard urethane is laminated on a part of a sound absorbing layer made of soft foamed urethane. It does not solve various problems.

Incidentally, the characteristic values of general rigid foamed urethane are as follows: the open cell ratio is about 15%, the hardness is about 70 N / cm ² , the density is about 0.1 g / cm ³ , and the cell diameter is about 0.1 to 0.5 mm. The average sound absorption rate of 2KHz sound is less than 10%.
Actual Kaihei 07-005966

  The present invention has been made in view of the above-described circumstances, and it should be solved to prevent the noise in the engine room and the noise outside the vehicle from entering the vehicle interior and to reduce the number of mounting steps. Let it be an issue.

A feature of the soundproof member for a dash panel of the present invention that solves the above problems is a soundproof member for a dash panel that is installed so as to face the dash panel, and the soundproof member for the dash panel is at least a soundproof member for a dash panel. It consists of a base material layer capable of holding the shape and a design layer provided on the side of the passenger compartment opposite to the dash panel with respect to the base material layer,
The base material layer is made of hard foamed urethane, which has an open cell structure with a hardness of 5 N / cm ² or more, a density of 0.03 to 0.15 g / cm ³ , and an open cell ratio of 50% or more. ,
By making the cell diameter 0.5 to 10 mm by including the defoaming agent component, the average sound absorption coefficient of the sound of 1 to 2 kHz is configured to be 45% or more in the entire soundproof member excluding the design layer. is there.

  The average sound absorption rate at 1 to 2 kHz here is the average value of sound absorption rate (measured by the normal incidence method according to the standard of JIS A 1405) at a frequency of 1/3 octave of 1, 1.25, 1.6 and 2 kHz. Say.

  A soft sound absorbing layer is preferably laminated on at least one surface of the base material layer on the dash panel side and the design layer side. In this case, the sound absorbing layer is preferably laminated on the surface of the base material layer facing the dash panel side.

  It is preferable that the cell formed inside the base material layer communicates with the outside of the base material layer. In the case of a base material layer formed by molding, it is desirable that the surface skin layer is configured to have an average thickness of 2 mm or less. Furthermore, it is preferable that a sound insulation layer is provided between the vehicle compartment side surface of the base material layer and the design layer.

  According to the soundproof member for a dash panel of the present invention, since the base material layer is formed of hard foamed urethane having the above characteristics, it has sufficient shape retention. Accordingly, it is difficult to be deformed when being mounted on the vehicle, so that it can be easily mounted and automation of assembly and the like is facilitated. And by having the said characteristic, a base material layer is excellent in the sound absorption characteristic, and can suppress that the noise in an engine compartment propagates into a vehicle interior. Furthermore, since the hard foamed urethane forming the base material layer also has an impact absorbing function, it is possible to protect the occupant's legs, and the light weight effect is not impaired.

  The soundproof member for a dash panel of the present invention is composed of at least a base material layer and a design layer. The base material layer is installed so as to face the dash panel, and the shape of the soundproof member is maintained by the rigidity of the base material layer. Therefore, since the soundproof member is not easily deformed when mounted on the vehicle, automation is facilitated and the soundproof member can be mounted with high accuracy.

This base material layer has an open cell structure with a hardness of 5 N / cm ² or more, a density of 0.03 to 0.15 g / cm ³ , and an open cell ratio of 50% or more. It is ~ 10mm, and the average sound absorption coefficient of sound of 1-2KHz is equal to that of soft foamed urethane because it is made of hard foamed urethane with each characteristic of 45% or more of the entire soundproofing member excluding the design layer. Sound absorption characteristics are expressed.

If the hardness is less than 5 N / cm ² , the shape tends to be deformed at the time of mounting, and there is a problem in shape retention. If the hardness exceeds 100 N / cm ² , the sound absorption function may be impaired due to sound reflection, etc. / Cm ² is preferable. Further, in order to suppress deformation at the time of mounting and to secure a larger sound absorbing function, the hardness is preferably 10 to 80 N / cm ² , more preferably 20 to 70 N / cm ² . The hardness is a numerical value measured according to JIS K 6400.

Density it is difficult to both the hardness and Ren'awaritsu the above range is less than 0.03 g / cm ^3, density of air permeability to provide a sufficient sound absorption properties decrease exceeds 0.15 g / cm ³ As it disappears, the weight increases. More preferably the density is 0.04~0.12g / cm ^3, particularly preferably 0.05~ 0.1g / cm ^3.

  If the open cell ratio is less than 50%, the sound absorption characteristics are insufficient and it is not practical as a soundproof member for a dash panel. The higher the open cell ratio, the better. It may be 100%, but if it is less than 50%, the sound absorption characteristics are insufficient and it is not practical as a soundproof member for a dash panel.

  Also, if the cell diameter is less than 0.5 mm, the sound absorption characteristics deteriorate, and if it exceeds 10 mm, sufficient strength cannot be obtained. In order to maintain strength and ensure a sound absorbing function, the cell diameter is more preferably 1 to 8 mm, further preferably 1.5 to 7 mm, and particularly preferably 2 to 6 mm.

  Furthermore, the soundproof member of the present invention has a characteristic that the average sound absorption coefficient of sound of 1 to 2 kHz is 45% or more in the whole soundproof member excluding the design layer. By having such a sound absorption characteristic, it is possible to effectively absorb the noise of the engine room, and it is particularly effective as a soundproof member for a dash panel.

  General hard foaming urethane is hard and has a small sound absorption characteristic because it has a small internal cell diameter. However, by foaming by adding an antifoaming agent, the surface tension of the foamed resin can be partially reduced, and when foamed, the cell has an open cell structure and the average cell diameter can be increased. Therefore, it is possible to produce a rigid foamed urethane having the characteristics as described above.

  In addition, a component and content required when manufacturing the rigid foaming urethane used for this invention are as follows.

  Examples of the polyol include polyether polyols, polyester polyols, polyether ester polyols, and the like, and these can be used alone or in combination of two or more.

  As the polyisocyanate, various polyisocyanates selected from aromatic, aliphatic and alicyclic systems can be used. Crude MDI is particularly preferred. The blending amount of this polyisocyanate is 50 to 500, preferably 80 to 400, more preferably 100 to 300 as an isocyanate index. When the isocyanate index is less than 50, foaming may not be performed normally, cracking may occur, and foam collapse may occur.

  The blowing agent is not particularly limited, but usually water is used. Further, alkylene chloride such as methylene chloride and ethylene chloride, isopentane and the like may be used. Although the compounding quantity of this foaming agent is not specifically limited, It is 1-15 mass parts normally with respect to 100 mass parts of polyols, Preferably it is 2-10 mass parts, More preferably, it is 3-8 mass parts.

  Examples of the antifoaming agent include silicone-based, oil-fat diameter, fatty acid-based, fatty acid ester-based, and phosphate ester-based ones. Of these, silicone antifoaming agents are particularly preferred. Examples of the silicone-based antifoaming agent include oil type, oil compound type, solution type, emulsion type, self-emulsifying type and powder type, and oil type is particularly preferable.

  The antifoaming agent preferably has an HLB value of 5 or less, more preferably 4 or less, still more preferably 0.5 to 3.5, and particularly preferably 1 to 3. When the HLB value exceeds 5, the hydrophilicity becomes too strong, and thus a rigid foamed urethane having an open cell structure may not be obtained. The HLB value is a value calculated based on the Griffin equation {20 × (mass ratio of hydrophilic groups)}.

  The blending amount of the antifoaming agent is usually 0.001 to 1 part by mass, preferably 0.002 to 0.8 part by mass, and more preferably 0.004 to 0.6 part by mass with respect to 100 parts by mass of the polyol. By blending in this range, open-celled rigid foamed urethane having a preferred average cell diameter is obtained. When the amount is less than 0.001 part by mass, the cells are rough and uniform cells cannot be obtained, and the hardness is insufficient. Moreover, when it exceeds 1 mass part, an average cell diameter will become small and a sound absorption characteristic will become inadequate.

  If a crosslinking agent is blended, a rigid foamed urethane having excellent resin strength can be formed by the crosslinked structure. Examples of the crosslinking agent include triols such as glycerin, trimethylolpropane and triethanolamine, and tetraols such as hydroxypropylethylenediamine and pentaerythritol.

  The thickness of the base material layer is desirably 5 mm or more. If the thickness is less than 5 mm, desired sound absorption characteristics may not be exhibited, or strength may be insufficient to maintain the shape. The thicker the thickness, the better, but the upper limit is determined by problems such as space constraints and weight increase.

  The base material layer can be formed into a predetermined shape by cutting out from a plate-like hard foamed urethane formed in advance, but it is desirable that the base material layer be formed into a final shape by molding. If it does in this way, even if the surface shape of a dash panel is complicated, it will be easy to make it the shape which follows the surface shape, and even if there is a difference in thickness locally, it can be formed easily. Therefore, it is possible to easily increase only the portion where it is desired to absorb the shock.

  Moreover, it is preferable to communicate from one surface of the base material layer to the other surface through cells inside the base material layer. That is, it is preferable that the cells formed inside the base material layer are not in a closed state, but are in a state in which the cells communicate with each other so as to be able to go back and forth. Accordingly, even when a skin layer is formed on the surface of the base material layer in the mold forming process, it is possible to avoid a decrease in sound absorption characteristics of the soundproof member due to the skin layer.

  In addition, as described above, since the substrate layer communicates from one surface to the other surface, it becomes possible to perform a resonator function together with the cells inside the soundproof member, so that higher soundproof performance is achieved. It can also be brought about.

  In the manufacturing process of the base material layer, by creating a cavity that communicates in advance from the surface of the base material layer to the inside, the base material layer is in a state of communication, but when the skin layer is formed on the surface of the base material layer Therefore, it is necessary to scrape the skin layer to expose an opening on the surface of the base material layer, or to form a hole in the skin layer, thereby forming a state in which the base material layer communicates as described above.

  Further, if the skin layer is made thin, the sound absorption characteristics can be satisfied without intentional communication. In this case, the average thickness of the skin layer may be 2 mm or less, more preferably 1 mm or less. Such a thin skin layer can be formed by shortening the foam molding time. Specifically, there are a method of increasing the mold temperature, a method of adjusting the curing time with a catalyst, and the like.

  The base material layer may have relatively low sound absorption characteristics depending on the combination of the above characteristic values. In such a case, it is preferable to further laminate a soft sound absorbing layer on the surface of the base material layer. Thus, by using a two-color laminate of hard foamed urethane and a soft sound-absorbing layer, the sound-absorbing characteristics may be improved in a wide frequency range compared to the case of only the hard foamed urethane having the same thickness and the same weight. . The material of the sound absorbing layer is particularly preferably soft foamed urethane having excellent sound absorbing characteristics.

  When soft urethane foams having different peak frequencies are combined, the individual characteristics are not necessarily utilized, and the sound absorption characteristics are not excellent in a wide frequency range. However, as in the present invention, it has been confirmed that when a hard foamed urethane and a soft foamed urethane having different peak frequencies are combined, the sound absorption characteristics are excellent in a relatively wide frequency range.

  When a soft sound-absorbing layer is further laminated, the sound-absorbing property is improved by using either the front or back surface of the base material layer, but the sound-absorbing layer is preferably laminated on the surface side of the base material layer facing the dash panel. In this way, since the followability to the surface shape of the dash panel is enhanced, the generation of a gap is suppressed and the soundproof performance is further improved. In this case, the thickness of the base material layer may be 5 mm or more as long as the shape retainability can be secured.

  It is also preferable that the base material layer has a sound insulation layer laminated on the surface opposite to the surface facing the dash panel. If it does in this way, whenever the sound which permeate | transmitted the base material layer reflects with a sound-insulation layer and a dash panel, it will pass through a base material layer, and, thereby, a sound absorption characteristic further improves. The sound insulation layer requires a certain amount of mass, but is preferably soft considering the secondary noise. For example, PVC, thermoplastic elastomer, rubber and the like can be used, and those in which various fillers are added to increase the mass are particularly preferable. This sound insulation layer may be formed at the interface between the base material layer and the design layer, but the sound insulation layer can be improved by improving the design by adjusting the color of other interior parts or applying a texture pattern. Can also serve as a design layer. In consideration of manufacturing cost and space restrictions, it is preferable that the sound insulation layer also serves as a design layer.

  The design layer is provided on the side opposite to the dash panel with respect to the base material layer, and when the design layer has a sound insulation effect as described above, the sound insulation layer is in contact with the base material layer. When there is no interposition, it is desirable to be integral with the base material layer. As a method of integration, the base material layer may be joined with an adhesive or the like. However, when the design layer is placed in the mold and the base material layer is foam-molded and integrated, the number of joining processes is reduced. Therefore, it is more preferable.

  The material of the design layer is not particularly limited as long as it basically has design properties, but in addition to the same PVC as the conventional sheet layer, the thermoplastic elastomer and rubber exemplified in the sound insulation layer Etc. can be formed. Further, if this design layer has a sound absorbing function like a foam or felt, it is also possible to absorb noise entering the room.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 1 shows a state in which the dash panel soundproof member of this embodiment is attached to the dash panel. The soundproofing member is formed of a base material layer 1 having a thickness of 5 to 30 mm and a design layer 2 having a thickness of 1 mm laminated integrally on the surface of the base material layer 1, and the surface of the base material layer 1 is a dash. It is attached so as to contact the panel 3.

The base material layer 1 is made of rigid foamed urethane, has an open cell structure with an open cell ratio of 95% or more, has a hardness of 30 N / cm ² , a density of 0.1 g / cm ³ , and a cell diameter of 4 mm. ing.

  The design layer 2 is formed of PVC containing 20 to 50% by weight of calcium carbonate, and has a hardness of Shore A50 or higher.

  This soundproofing member first forms the design layer 2 into a predetermined shape by a vacuum forming method, arranges the design layer 2 along the mold surface of the foaming mold, and includes an antifoaming agent with the composition shown in Table 1. The base material layer 1 was formed from a hard foamed urethane resin. Thereby, the design layer 2 is integrally joined to the base material layer 1. A skin layer (not shown) having a thickness of 1 mm is formed on the surface of the base material layer 1.

Since the soundproof member of Example 1 has the base material layer 1 having a hardness of 30 N / cm ² and excellent shape retention, deformation is unlikely to occur during mounting on the dash panel 3, and the assembly process can be automated. It can be done easily.

(Example 2)
FIG. 2 shows a state in which the dash panel soundproof member of this embodiment is attached to the dash panel. This soundproofing member includes a base material layer 10 made of rigid foamed urethane similar to that in Example 1, and a sound absorbing layer 11 made of soft foamed urethane B formed with the composition shown in Table 2 and having excellent sound absorption characteristics in a low frequency range. The design layer 2 is the same as that of Example 1 except that the same design layer 2 as that of Example 1 is integrally laminated on the surface of the base material layer 10. The sound-absorbing layer 11 has an open cell structure with an open cell rate of 92%, and has various properties such as a hardness of 3 N / cm ² , a density of 0.1 g / cm ³ , and a cell diameter of 0.2 mm.

  Since the soundproof member of Example 2 has the base material layer 10 that is excellent in shape retention as in Example 1, deformation is unlikely to occur during attachment to the dash panel 3. Further, since the soft sound-absorbing layer 11 is provided on the surface facing the dash panel 3, it is easy to follow the surface shape of the dash panel 3 and a gap is not easily formed, so that the soundproofing characteristics are further improved.

Example 3
The soundproof member of Example 2 was pierced 7 mm from the surface with a sword-shaped needle to form a needle hole. The diameter of one needle was 1 mm, and the needle holes were formed at a ratio of ^two to 1 cm ² of the surface area.

  FIG. 3 shows an enlarged cross-sectional view of the soundproof member of this embodiment. This soundproofing member is composed of a base material layer 10 made of the same hard foamed urethane as in Example 1 and a sound absorbing layer 11 made of the same soft foamed urethane B as in Example 2, and is applied to the surface of the base material layer 10. A design layer 2 similar to that in Example 1 is integrally laminated. The base material layer 10 has a needle hole 12 penetrating the base material layer 10 in the thickness direction.

  Since the soundproof member of Example 3 has the base material layer 10 that is excellent in shape retention as in Example 1, deformation is unlikely to occur during attachment to the dash panel 3. Furthermore, since the soft sound-absorbing layer 11 is provided on the surface facing the dash panel 3 as in the second embodiment, the soundproofing characteristics are further improved because the surface shape of the dash panel 3 is easy to follow and a gap is hardly formed.

(Comparative Example 1)
The base material layer 1 of Example 1 was formed from the conventionally known soft foamed urethane A with the formulation shown in Table 3 as Comparative Example 1. This base material layer 1 has an open cell structure with an open cell ratio of 90 to 95%, a hardness of 0.01 to 0.05 N / cm ² , a density of 0.07 g / cm ³ , and a cell diameter of 0.1 to 0.5 mm. It has.

  In the soundproof member of Comparative Example 1, since both the base material layer 1 and the design layer 2 are soft, the shape retention is inferior, and deformation is likely to occur in the assembly process.

(Comparative Example 2)
Comparative Example 2 was obtained by forming the base material layer 1 of Example 1 from the soft foamed urethane B used for the sound absorbing layer 11 of Example 2.

  In the soundproof member of Comparative Example 2, since the base material layer 1 and the design layer 2 are both soft as in Comparative Example 1, the shape retention is inferior, and deformation is likely to occur in the assembly process.

(Comparative Example 3)
A base material layer 1 was formed in the same manner as in Example 1 except that the temperature of the foaming mold was changed. In both Example 1 and Comparative Example 3, a skin layer is formed on the base material layer 1, but the thickness of the skin layer of Example 1 is 1 mm, whereas that of Comparative Example 3 is 3 mm. .

  Since the soundproof member of Comparative Example 3 has the base material layer 1 excellent in shape retention as in Example 1, it is difficult to be deformed when attached to the dash panel 3.

  In addition, in order to confirm the sound absorption characteristic in each Example and a comparative example, the test of 1-4 described below was done.

<Test Example 1>
In order to compare the sound absorption characteristics of Example 1 and Comparative Example 1, the sound absorption characteristics were evaluated using test pieces in which the thickness of the base material layer 1 was 15 mm. The design layer 2 is not formed. The sound absorption characteristics were determined by measuring the sound absorption rate at each frequency according to the method specified in JIS A 1405, and comparing the sound absorption rate of the sound with a frequency of 200 to 3150 Hz. The results are shown in FIG.

  As shown in FIG. 4, the base material layer of Example 1 has an average sound absorption rate of 1 to 2 KHz of sound of 45% or more (46.9%), and the average sound absorption rate of sound of 1 to 2 kHz in the base material layer of Comparative Example 1 ( 39.4%) higher sound absorption characteristics. Moreover, it shows a sound absorption characteristic higher than that of Comparative Example 1 in a high frequency range exceeding 1 KHz, and is found to be particularly suitable as a soundproof member for a dash panel.

<Test Example 2>
In order to compare the sound absorption characteristics of Example 2, Comparative Example 2 and Example 1, a test piece having a total thickness of the base material layer 10 and the sound absorption layer 11 and a thickness of the base material layer 1 of 15 mm was used. The sound absorption characteristics were evaluated in the same manner as in Example 1. The design layer 2 is not formed. Moreover, in the test piece of Example 2, the thickness of the base material layer 10 is 5 mm, and the thickness of the sound absorbing layer 11 is 10 mm. The results are shown in FIG.

  From FIG. 5, Example 2 has an average sound absorption coefficient of 45% or more (70.4%) for sound of 1 to 2 kHz, and higher sound absorption characteristics than the average sound absorption coefficient (46.9%) of sound of 1 to 2 kHz in Example 1. Show. In addition, Example 2 shows higher sound absorption characteristics than Comparative Example 2 in a high frequency range of 2 kHz or higher, and is clearly superior in sound absorption characteristics in a wide frequency range.

  That is, by combining soft foamed urethane having good sound absorption characteristics in a relatively low frequency range, high sound absorption characteristics can be secured in a wide frequency range even with the same thickness and substantially the same weight.

<Test Example 3>
In order to compare the sound absorption characteristics of Example 2 and Example 3, the sound absorption characteristics were evaluated in the same manner as in Test Example 1 using test pieces having a total thickness of the base material layer 10 and the sound absorption layer 11 of 15 mm. The results are shown in FIG. The design layer 2 is not formed.

  From FIG. 6, it can be seen that in Example 3, the average sound absorption coefficient of sound of 1 to 2 kHz is further improved to 73.1% than in Example 2, and this is clearly the effect of forming a needle hole. That is, by forming a needle hole (communication portion) that communicates with the cells inside the base material layer 10 in the skin layer, the sound absorption characteristics are further improved.

<Test Example 4>
In order to compare the sound absorption characteristics of Example 1 and Comparative Example 3, each of the sound absorption characteristics was evaluated in the same manner as in Test Example 1 using a test piece with a base layer 1 having a thickness of 15 mm. Shown in The design layer 2 is not formed.

  From FIG. 7, in Comparative Example 3, the average sound absorption rate of the sound of 1 to 2 kHz is lower than that of Example 1 at 19.5%, and it is clear that the sound absorption rate is lowered when the skin layer is thickened.

  The soundproof member of the present invention can be used as a soundproof member for dash panels of various automobiles such as passenger cars, trucks, buses, and industrial vehicles.

It is sectional drawing shown in the state which attached the soundproof member of one Example of this invention to the dash panel. It is sectional drawing which shows the soundproof member of 2nd Example of this invention in the state attached to the dash panel. It is an expanded sectional view showing the soundproof member of the 3rd example of the present invention in the state where it attached to the dash panel. It is a graph which shows the relationship between a frequency and a sound absorption coefficient. It is a graph which shows the relationship between a frequency and a sound absorption coefficient. It is a graph which shows the relationship between a frequency and a sound absorption coefficient. It is a graph which shows the relationship between a frequency and a sound absorption coefficient.

Explanation of symbols

1: Base material layer 2: Design layer 3: Dash panel
10: Base material layer 11: Sound absorption layer

Claims (6)

A dash panel soundproofing member installed to face the dash panel,
The dash panel soundproof member includes at least a base material layer capable of maintaining the shape of the dash panel soundproof member, and a design layer provided on the side of the passenger compartment opposite to the dash panel with respect to the base material layer. Become
The base material layer is formed from rigid foamed urethane,
The rigid foamed urethane has an open cell structure with a hardness of 5 N / cm ² or more, a density of 0.03 to 0.15 g / cm ³ , and an open cell ratio of 50% or more.
By making the cell diameter 0.5 to 10 mm by including the defoaming agent component, the average sound absorption coefficient of the sound of 1 to 2 KHz is configured to be 45% or more in the entire soundproof member excluding the design layer. Soundproof member for dash panel characterized by   The soundproof member for a dash panel according to claim 1, wherein a soft sound absorbing layer is laminated on at least one surface of the base material layer on the dash panel side and the design layer side.   The soundproof member for a dash panel according to claim 2, wherein the sound absorbing layer is laminated on a surface of the base material layer facing the dash panel side.   The soundproof member for a dash panel according to any one of claims 1 to 3, wherein a cell formed inside the base material layer communicates with an outside of the base material layer.   The soundproof member for a dash panel according to any one of claims 1 to 3, wherein the skin layer on the surface of the base material layer formed by molding is configured to have an average thickness of 2 mm or less.   The soundproof member for a dash panel according to any one of claims 1 to 5, wherein a sound insulation layer is provided between a surface of the base material layer on the vehicle compartment side and the design layer.

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