JP2013139188A - Insulator in engine room of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorbing material that exhibits excellent sound-absorbing properties from a low frequency domain to a high frequency domain without increasing a layer thickness or weight of the sound absorbing material, and in which a large number of rough cotton are reused.SOLUTION: An insulator in an engine room of an automobile includes the sound absorbing material 1 provided with: a sound absorbing layer 2 formed of a fiber material mainly containing the rough cotton, a binder resin and a glass fiber; a synthetic resin-made film 3 overlapped with the sound absorbing layer 2; and a skin layer 4 formed of a nonwoven fabric overlapped with the synthetic resin-made film 3. On the synthetic resin-made film 3, a predetermined opening diameter, a predetermined pitch distance, and a vent hole 5 having a predetermined rate of hole area are formed.

Description

  The present invention particularly relates to an insulator for reducing the noise of an automobile, and more particularly to a sound absorbing material suitable for reducing noise in an engine room.

  As an insulator in an engine room for reducing engine noise of an automobile, a sound absorbing material is disposed on the inner surface of a bonnet or the like. As a sound-absorbing material used for such an application, a material in which a nonwoven fabric is laminated and integrally formed on the surface of a glass fiber mat to which a binder resin such as a phenol resin is attached is known (Patent Documents 1 and 2). .

Japanese Utility Model Publication No. 5-12299 JP 2006-027467 A

  Recently, recyclability is strongly demanded from the viewpoint of the environment, and it is strongly demanded to reuse felts of used sound-absorbing materials, particularly cotton. Although it is actually possible to mix used felt and cotton if the amount is small, the amount of mixing is limited because the properties such as sound absorption performance deteriorate, so much is mixed. The current situation is not.

  Moreover, in the thing of patent document 1 and 2, since the thermosetting resin is impregnated into the sound-absorbing base material, it is molded into a required shape by hot press molding and has heat resistance and rigidity. However, if a large amount of cotton (such as several tens of weight percent) is mixed into such a sound absorbing material, the sound absorbing performance will deteriorate in all regions from the low frequency region to the high frequency region, resulting in an acceptable sound absorbing performance. It was not reached.

  As a countermeasure, it has been found that increasing the layer thickness or the weight of the entire sound absorbing material improves the sound absorbing performance. However, because insulators in engine rooms are used in limited engine rooms, increasing the thickness of the sound absorbing material tends to be disliked, and increasing the thickness to satisfy the sound absorption characteristics Was not suitable as an insulator in the engine room.

  Therefore, the present inventors tried a method for increasing the weight. For example, the basis weight of the entire sound absorbing material was increased by 20%. Then, it was found that the performance close to the original sound absorption characteristic can be obtained. However, increasing the basis weight increases the weight, which is a technique against the weight reduction of the vehicle body and is difficult to be adopted. Furthermore, when the weight increases, the cost increases, which is disadvantageous in terms of workability and handling, and a method that does not increase the weight is strongly desired.

  Therefore, the present inventors further examined another method that does not increase the layer thickness and weight of the sound absorbing material. Specifically, the present inventors have tried to interpose a film layer in a sound absorbing material composed of a sound absorbing layer and a skin layer. However, simply by interposing a film, even if the low frequency region is improved, the high frequency region is worsened, and good sound absorption performance is not obtained in all regions from the low frequency region to the high frequency region.

  Therefore, in the present invention, without increasing the layer thickness and weight of the sound absorbing material, an object is to provide a sound absorbing material that exhibits good sound absorption characteristics from a low frequency region to a high frequency region and can be reused with a lot of miscellaneous cotton. To do.

  The first invention is made of a synthetic resin having a skin layer made of nonwoven fabric, a sound absorbing layer made of a fiber material, a binder resin and glass fibers, and a synthetic resin having an air vent between the skin layer and the sound absorbing layer. An insulator in an engine room of an automobile provided with a film, wherein a main material of a fiber material of the sound absorbing layer is made of cotton.

  According to a second aspect of the invention, there is provided an insulator in an engine compartment of an automobile according to the first aspect of the invention, wherein the sound absorbing layer is 40 to 55% by weight of the cotton, 25 to 35% by weight of the binder resin, and the glass. The fiber is characterized by 20 to 25% by weight.

  3rd invention is the insulator in the engine room of the motor vehicle of the 1st or 2nd invention, The opening diameter of this ventilation hole of this synthetic resin film is (phi) 1-10 mm, The pitch space | interval is 5-15 mm, The open area ratio is 2.5 to 10%.

  According to a fourth aspect of the invention, in the insulator in an engine compartment of an automobile according to the third aspect of the invention, the thickness of the synthetic resin film is 20 to 50 μm.

According to a fifth aspect of the invention, in the insulator in the engine compartment of the automobile according to any one of the first to fourth aspects, the basis weight of the sound absorbing layer is 500 to 2000 g / m ² , and the layer thickness of the entire insulator is Is 5 to 30 mm.

  In the first aspect of the invention, it is possible to reuse a large amount of miscellaneous cotton without increasing the layer thickness and weight of the sound absorbing material, and to exhibit good sound absorbing characteristics from the low frequency region to the high frequency region.

  In the 2nd invention, the insulator in an engine room which shows a still more favorable sound absorption characteristic can be obtained by setting appropriately the ratio of a fluff, binder resin, and glass fiber.

  According to the third aspect of the present invention, by appropriately selecting the aperture diameter, pitch interval, and aperture ratio of the synthetic resin film, the sound absorption performance due to the membrane vibration of the synthetic resin film and the sound absorption layer entering the sound absorption layer through the ventilation holes. Therefore, it is possible to effectively achieve both the sound absorption performance and balance, so that high sound absorption performance can be obtained in a wide frequency range from a low frequency range to a high frequency range.

  In the fourth invention, higher sound absorption performance can be obtained in a wide frequency range from a low frequency range to a high frequency range.

  In the fifth invention, as the insulator in the engine room, high sound absorption performance can be obtained without increasing the overall layer thickness.

It is an embodiment of the present invention and is a sectional view schematically showing a laminated structure of insulators. It is a graph which compares and shows the sound absorption performance of the Example and comparative example of this invention. It is a table | surface which shows the sound absorption performance at the time of changing the thickness of a synthetic resin film, an aperture diameter, and an aperture ratio.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  As shown in FIG. 1, a sound absorbing material 1 constituting an insulator in an engine room is integrally formed by laminating a synthetic resin film 3 on a sound absorbing layer 2 and a skin layer 4 thereon. A plurality of ventilation holes 5 are formed in the synthetic resin film 3.

  The sound absorbing material 1 is attached to a wall surface in an engine room of an automobile (not shown) and is used to reduce noise in the engine room.

  The sound-absorbing layer 2 is required to have a high sound-absorbing property, as well as formability and shape retention. The sound absorbing layer 2 is made of glass fiber, binder resin, and fiber material. The binder resin is made of at least one selected from a phenol resin, an acrylic resin, polyvinyl alcohol, and polyvinyl acetate. The fiber material is mainly made of cotton. As used herein, the term “cotton” is representative of used resin fibers, natural fibers, and the like, and includes, for example, crushed thermosetting felt, cotton, and the like.

  The cotton of the sound absorbing layer 2 is preferably 40 to 55% by weight, the binder resin is 25 to 35% by weight, and the glass fiber is preferably 20 to 25% by weight. If the amount of glass fiber is too small, the shape retention and sound absorption performance will deteriorate. If the amount of the binder resin is too small, the adhesiveness and moldability are deteriorated. Therefore, it is preferable that the glass fiber and the binder resin are within the above ranges. Although it is preferable that as much cotton as possible can be mixed, glass fiber and binder resin are relatively reduced in this case, so that the above range is preferable.

  The synthetic resin film 3 remains without being completely melted at the time of heat molding, and a polyethylene resin, particularly LDPE (low density polyethylene resin) is preferable in order to obtain appropriate film vibration characteristics. The thickness of the synthetic resin film 3 is preferably 20 to 50 μm. If it is too thick, the membrane vibration property is deteriorated and the sound absorbing performance is deteriorated.

  The vent holes 5 of the synthetic resin film 3 preferably have an aperture diameter of φ1 to 10 mm and a pitch interval of 5 to 15 mm and an aperture ratio of 2.5 to 10%. If the aperture diameter is too small, the predetermined sound absorbing performance cannot be obtained, and if it is too large, the membrane vibration function is lowered.

  If the pitch interval is too wide, the sound absorption performance in the high frequency region is lowered, and if it is too narrow, the sound absorption performance in the low frequency region is lowered.

  If the aperture ratio is small, the sound absorption performance in the high frequency region is lowered, and if it is large, the sound absorption performance in the low frequency region is lowered. Therefore, the above range is preferable.

  The aperture diameter, pitch interval, and aperture ratio of the vent hole 5 of the present invention are values before heat forming. At the time of thermoforming, the value may be slightly changed depending on the molten state. Moreover, the preferable range of an aperture diameter and an aperture ratio changes with thickness of the synthetic resin film 3, and the range of the allowable aperture ratio becomes wider, so that thickness is thin and an aperture diameter is small.

The total layer thickness of the sound absorbing material 1 (that is, the total thickness of the sound absorbing layer 2, the synthetic resin film 3, and the skin layer 4) is preferably 5 to 30 mm. The basis weight of the entire layer is preferably 500 to 2000 g / m ² . If it is thicker than this range, it cannot be employed in the engine room space, and if it is too thin, the necessary functions cannot be obtained.

  The skin layer 4 is a nonwoven fabric made of a synthetic resin mainly composed of PET or PP, or a laminate thereof. The skin layer 4 is required to have heat resistance in the engine room, appearance, and prevention of glass fiber scattering.

  The manufacturing method of the insulator in an engine room of the present invention is as follows. Prepare a sheet material that will be the sound absorbing layer 2 mixed with cotton, glass fiber and binder resin. Overlay the synthetic resin film 3 and the skin material 4 on this sheet material, and heat and press in a mold to form. . The molding temperature during molding is preferably 160 to 250 ° C. If the molding temperature is too low, the moldability and the adhesive strength are deteriorated. If the molding temperature is too high, the synthetic resin film is completely melted.

  Next, the present invention will be specifically described with reference to examples.

Example 1
The skin layer is a PET resin nonwoven fabric having a basis weight of 40 g / m ² .

  The synthetic resin film is LDPE (low density polyethylene resin) having a thickness (thickness before molding) of 20 μm. The hole diameter of the air holes of this film is φ2 mm, the hole area ratio is 10%, and the pitch. The interval is 10 mm.

The sound-absorbing layer has a basis weight of 1000 g / m ² and is composed of 23% by weight of glass fiber, 30% by weight of phenol resin (binder resin), and 47% by weight of cotton.

  The total thickness of the sound absorbing material is 20 mm.

A sound-absorbing material comprising a sound-absorbing layer, a synthetic resin film, and a skin layer is maintained at a mold temperature of 200 ° C., a mold interval of 20 mm and 10 kg / cm ² , and held for 60 seconds. Such a sound absorbing material was produced.

(Example 2)
In Example 2, the difference from Example 1 is that glass fiber is 25% by weight, phenol resin is 35% by weight, and cotton is 40% by weight. Others are the same as Example 1.

(Example 3)
In Example 3, the difference from Example 1 is that the glass fiber is 22% by weight, the phenol resin is 28% by weight, and the cotton is 50% by weight. Others are the same as Example 1.

Example 4
In Example 4, the difference from Example 1 is that the glass fiber is 20% by weight, the phenol resin is 25% by weight, and the cotton is 55% by weight. Others are the same as Example 1.

(Comparative Example 1)
In contrast to Example 1, the sound absorbing layer was made of glass fiber and phenol resin. Actually, the skin layer is a non-woven fabric made of PET resin having a basis weight of 40 g / m ² , the sound absorbing layer is composed of 60% by weight of glass fiber and 40% by weight of phenol resin, and the basis weight of the sound absorbing layer is 1000 g / m ^2. The thickness was set to 20 mm. Unlike Example 1, the comparative example 1 is not provided with a synthetic resin film.

(Comparative Example 2)
Comparative Example 2 is a sound absorbing layer in which miscellaneous cotton is added to Comparative Example 1 by reducing the number of glass fibers and phenolic resin in the sound absorbing layer.

Actually, the skin layer is a non-woven fabric made of PET resin having a basis weight of 40 g / m ² , and the sound absorbing layer is made of glass fiber, phenol resin, and cotton, respectively 23%, 30%, and 47% by weight. The basis weight was 1000 g / m ² and the thickness of the sound absorbing material was 20 mm. Others are the same as those in Comparative Example 1.

(Comparative Example 3)
Comparative Example 3 is obtained by increasing the basis weight of the sound absorbing layer as compared with Comparative Example 2.

Actually, the skin layer is a non-woven fabric made of PET resin having a basis weight of 40 g / m ² , and the sound absorbing layer is made of glass fiber, phenol resin, and cotton, respectively 23%, 30%, and 47% by weight. The basis weight was 1200 g / m ² and the thickness of the sound absorbing material was 20 mm. Others are the same as those of Comparative Example 2.

  The sound absorption performance of Example 1 and Comparative Examples 1 to 3 was compared. In order to measure the sound absorption coefficient, each sample was prepared by cutting to φ50 mm.

  FIG. 2 shows the results of measuring the reverberation chamber method sound absorption rate according to JIS A 1409 for Example 1 and Comparative Examples 1 to 3. At the same time, Comparative Example 1 shows good results, but Comparative Example 1 is not preferable because it does not reuse any cotton. On the other hand, in Comparative Example 2 in which miscellaneous cotton was added in the same manner as in Example 1, the sound absorption performance was degraded in all of the low frequency region to the high frequency region. In Comparative Example 3 in which the basis weight is increased compared to Comparative Example 2, the sound absorption performance is restored to the level of Comparative Example 1, but since Comparative Example 3 has a larger basis weight than Comparative Examples 1 and 2, Not suitable as an engine room insulator. On the other hand, in Example 1, although the basis weight is the same as that of Comparative Examples 1 and 2, and the mixed cotton is considerably mixed in the sound absorbing layer, any of Comparative Examples 1 to 3 may be used. Sound absorption performance was shown. This can be said to be because the synthetic resin film is provided with the air holes having the predetermined aperture diameter at the predetermined pitch intervals and the predetermined aperture ratio.

  In addition, the following experiment was conducted in order to confirm the relationship between the thickness of the synthetic resin film, the diameter of the air holes, and the hole area ratio. That is, in Example 1, the film thickness was set to 20 μm, 30 μm, 50 μm, and 100 μm, and the diameter of the air holes was changed to φ2 mm, φ4 mm, φ6 mm, and φ10 mm, and the aperture ratio was 2.5%. The sound-absorbing characteristics were measured with the percentage changed to%, 7.5%, and 10%. The pitch interval was constant at 10 mm. The method for measuring the reverberation chamber sound absorption rate conformed to JIS A 1409.

  As a result, the results of the reverberation room sound absorption coefficient are shown in FIG. 3, where 70% or more is indicated by ○, 60% or more by Δ, and less than 60% by X. Moreover, the measurement result about Examples 1-4 was also shown in FIG.

  As described above, the effective aperture ratio and aperture diameter differ depending on the thickness of the synthetic resin film, but by setting to an appropriate value, without increasing the thickness and weight, Good sound-absorbing characteristics were obtained, and the recyclability was greatly improved by mixing miscellaneous cotton, and a sound-absorbing material superior to the conventional one could be obtained.

  It is suitable for an insulator in an engine room that reduces noise in the engine room of an automobile.

DESCRIPTION OF SYMBOLS 1 Sound-absorbing material 2 Sound-absorbing layer 3 Synthetic resin film 4 Skin layer 5 Vent

Claims (5)

A skin layer made of non-woven fabric,
A sound absorbing layer made of fiber material, binder resin and glass fiber;
An insulator in an engine room of an automobile provided with a synthetic resin film having a vent hole interposed between the skin layer and the sound absorbing layer,
An insulator in an engine compartment of an automobile, wherein the fiber material of the sound absorbing layer is mainly made of cotton. The insulator in the engine compartment of the automobile according to claim 1,
The sound-absorbing layer is composed of 40 to 55% by weight of the cotton, 25 to 35% by weight of the binder resin, and 20 to 25% by weight of the glass fiber. Inner insulator. In the insulator in the engine room of the automobile according to claim 1 or 2,
Inside the engine room of an automobile, wherein the synthetic resin film has a vent diameter of φ1 to 10 mm, a pitch interval of 5 to 15 mm, and an aperture ratio of 2.5 to 10%. Insulator. In the insulator in the engine room of the automobile according to claim 3,
An insulator in an engine compartment of an automobile, wherein the synthetic resin film has a thickness of 20 to 50 µm. The insulator in the engine compartment of the motor vehicle according to any one of claims 1 to 4,
The basis weight of the sound absorbing layer is 500 to 2000 g / m ² ,
An insulator in an engine room of an automobile, wherein the layer thickness of the entire insulator is 5 to 30 mm.

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