JPH09251295A - Sound absorbing material and sound insulating cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorbing material and sound insulating cover which have sound absorption and sound insulation performance of a high level and has low oil absorptivity and water absorptivity and are low in cost. SOLUTION: This sound absorbing material is constituted by coating the surface or entire surface of a melamine resin foam 1 with a surface material 2 having oil repellent and water repellent properties. This sound insulating cover is constituted by using this sound absorbing material and the sound insulating material 4 in combination. The sound absorbing rate of the melamine resin foam 1 coated with the surface material is good and the melamine resin foam formed to >=5 to <=18mm thickness is particularly good in the sound absorbing coefft. of sounds in a range of 1 to 2kHz. The sound absorbing material which is low in cost, light in weight and smaller in space and has the excellent sound absorbing characteristic is thus formed. The sound insulating cover having the excellent sound insulating characteristic by combination use of the sound insulating material 4 is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing member and a sound insulating cover for preventing or reducing engine noise mounted on a vehicle from leaking out of the vehicle.

[0002]

2. Description of the Related Art A sound insulation cover for reducing the noise of an engine mounted on a vehicle from leaking out of the vehicle has a structure in which a sound absorbing material that absorbs sound and a sound insulating material that shields the sound are combined. FIG. 6 shows a conceptual diagram of the sound insulation cover. A sound insulating plate 22 is provided around a sound source 21 such as an engine, and a sound absorbing material 23 is installed on the inner surface of the sound source 21 to prevent or reduce the leakage of noise to the outside. In general, the sound insulation performance of the sound insulation plate 22 follows the mass law, and sound can be shielded better as the mass increases. Therefore, inexpensive and thin (space-saving) coated steel sheets have become the mainstream of the sound insulation plates. As a substitute for the sound insulation plate, a blow molding product made of synthetic resin with an air layer in the middle to improve sound insulation performance more than the mass law, and a sound insulation material made of glass fiber reinforced resin that can integrally mold complex shapes are also used. ing. On the other hand, as the sound absorbing material, glass wool is widely used because it is inexpensive, has excellent heat resistance and durability, and has relatively good sound absorbing property.

FIG. 7 shows a cross section of a glass wool sound absorbing material. Aluminum foil 25 is provided on both sides of glass wool 24 impregnated with about 10 Wt% phenolic resin binder, and aluminum foil 26 for sealing is attached to the periphery with an adhesive or a pressure-sensitive adhesive to prevent the glass wool from being exposed.
The aluminum foil reflects heat, prevents oils and fats such as fuel and oil, and water such as rainwater from penetrating into the glass wool to prevent deterioration of sound absorbing performance, and improves the handling of the glass wool. Usually, this sound absorbing material is provided with a hole and is attached to the sound insulating plate with a clip, a hook or the like. Some of the aluminum foils 25 and 26 have glass fibers bonded to the back surface for reinforcement using a resin such as polyethylene as a binder. For parts where oils and fats and water do not easily penetrate, use glass wool 2
The aluminum foil 25 provided on both sides or only one side of No. 4 and simply crushed at the same time when the terminal portions are stuck together, or those simply sealed with a rubber-based adhesive for sealing are employed.

Japanese Unexamined Patent Publication No. 59-222894 discloses a sound absorbing / damping material in which a damping material and a sound absorbing material are integrated. Further, Japanese Utility Model Application Laid-Open No. 62-94033 describes a sound insulation material in which a glass cloth layer is provided on both sides of glass wool and an FRP layer is formed on at least one of aluminum foils of the glass cloth layer. In addition, 52-75
Japanese Unexamined Patent Publication No. 222 discloses an automobile interior member in which a synthetic resin, synthetic rubber, or a sound-insulating material such as felt or a sound-absorbing sheet is attached to one surface of a paper corrugated board to form an integral structure.

[0005]

The conventional sound-absorbing material shown in FIG. 7 mounted on a sound-insulating plate made of steel plate has a high processing cost because the entire circumference of the glass wool is sealed with aluminum foil, which increases the cost. When the seal portion of the foil is peeled off by heat of the engine, oil mist, or the like, the sound absorbing property may be deteriorated due to the permeation of oils and fats and water. In addition, a clip mounting hole that penetrates aluminum foil and glass wool also reduces sound absorption. In recent years, social demands on vehicle noise have become strict, and regulations on vehicle exterior noise of automobiles, especially trucks, have been tightened.Therefore, there is a need for sound absorbing materials and sound insulation materials that lower the noise level around the exterior of the vehicle at a lower cost than before. There is. Moreover, 1 KHz to 2 KH is required to reduce the noise level outside the vehicle.
It is said that the effect of increasing the sound absorption coefficient of the sound source frequency of z is great.

The one described in the above-mentioned Japanese Patent Laid-Open No. 59-222894 shows only the shape constitution of the damping material and the sound absorbing material, and there is no description about the characteristics of both materials, and the obtained performance and cost are Unknown. In addition, actual development Sho 62-9403
The materials described in Japanese Patent Publication No. 3 and Japanese Utility Model Laid-Open No. 52-75222 do not reach the current required performance in sound absorption and sound insulation, and sound absorbing materials (glass wool, paper corrugated cardboard, felt) are oil absorbing and water absorbing. Sound absorption performance deteriorates. The present invention has a higher level of sound absorption / insulation performance than conventional products,
It is an object of the present invention to provide a low-cost sound-absorbing material and sound-insulating cover with little oil absorption and water absorption.

[0007]

The present invention is a sound absorbing material in which the surface or the whole surface of a melamine resin foam is covered with an oil-repellent / water-repellent surface material, and the sound absorbing material and the sound insulating material are used together to provide a sound insulating cover. To do. The thickness of the melamine resin foam is preferably 5 mm or more and less than 18 mm.
The sound absorption of melamine resin foam is good, and the thickness of the melamine resin foam is 5 mm or more and less than 18 mm.
It is possible to form a sound-absorbing material with excellent sound-absorbing properties by combining it with a sound-insulating material by forming a sound-absorbing material with excellent sound-absorbing properties in the range of KHz to 2 KHz, which is low cost, lightweight, space saving, and has excellent sound absorbing properties. it can. Also, by coating with an oil-repellent / water-repellent surface material, the ingress of oils and fats and water is prevented, and the deterioration of the sound absorbing performance of the melamine resin foam is prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of a first embodiment of the present invention. The surface material 2 is adhered to the melamine resin foam 1 with the adhesive layer 3, and the sound insulating material 4 is attached to the back surface with an adhesive, an adhesive or a double-sided adhesive tape 5. Since the melamine resin foam 1 has water-absorbing property and oil-absorbing property, the sound-absorbing property is deteriorated at the time of water-absorbing and oil-absorbing, so that a surface material is provided to prevent this, and at the same time, the peak of the sound-absorbing property with respect to the frequency is especially used for vehicles. It can be set to around the required 1 KHz to 2 KHz.

The melamine resin foam of the sound absorbing material 1 may be of any size, shape, or thickness from "Basotect" (slab foam) manufactured by BASF, or may be a flat plate having a specified size. Cut out and use. The surface material is aluminum foil or aluminum foil reinforced with glass fiber, resin film (6 nylon, 66 nylon, polyester,
Polycarbodiimide is used as adhesive because most of the cases require heat resistance, such as polypropylene, fluororesin, etc.), non-woven fabric (polyester, polypropylene, etc.) with oil and water repellency, either alone or in combination. It is desirable to use the one based on (Calpositite manufactured by Nisshinbo). Further, as the sound insulating material 4, it is possible to use an appropriate material having a high sound insulating property such as a coated steel plate, a hollow double wall resin plate, a glass fiber reinforced resin, and an aluminum alloy plate.

FIG. 2 shows a cross section of the second embodiment.
Various methods can be used to attach the sound absorbing material to the sound insulating material 4. In FIG. 2A, the end portion of the surface material 6 is bent, and the melamine resin foam 1 is bonded to the inner surface of the surface material 6 with the adhesive layer 3. While covering, the surface material 6 and the melamine resin foam 1 are both attached to the sound insulating material 4 with an adhesive / adhesive or a double-sided adhesive tape 5,
It covers the entire surface of the melamine resin foam 1. FIG. 2B is the same as FIG. 2A, but the application site of the adhesive layer 3 to the melamine resin foam 1 is different.

FIG. 3 shows a cross section of the third embodiment.
FIG. 3A shows that the entire surface of the melamine resin foam 1 is covered with the adhesive layer 3 by being adhered to the inside of the surface materials 7, 8 having the recesses, and the peripheral portions of the surface materials 7, 8 are adhered by the adhesive layer 9. This portion is fixed to the sound insulating material 4 by the hook 10. In FIG. 3B, a thermosetting adhesive 3'is applied to the entire one surface of the surface materials 7'and 8 ', and the melamine resin foam 1 is placed in the middle of the adhesive application surface to heat the surface material 7', The resin foam layer is crushed and hardened by compressing and heating the entire circumference of the end portion of 8'which does not require the sound absorbing function to the state shown in 1a, and this portion P has a flange-like rigidity. is there. A hole is provided in the part P and is fixed to the sound insulating material with a rivet or the like.

FIG. 4 shows a cross section of the fourth embodiment.
The melamine resin foam 1 is fitted into the recess of the surface material 11, and a synthetic resin such as PP, PE or PP + PE is adhered by an adhesive layer 9 to a sound insulating material 12 having a hollow portion formed by blow molding. The sound insulation performance can be further improved by providing a hollow portion in the sound insulation material.

FIG. 5 shows a cross section of the fifth embodiment.
The shapes of the sound absorbing material, the surface material, and the sound insulating material and the combinations thereof have many modes, and these modes are shown. FIG. 5A shows the surface material 1 on both front and back surfaces of the melamine resin foam 1.
3 and 14 are bonded together and fixed to a peripheral end portion of a sound insulating material 15 having a concave space by a plurality of clips 16. In FIG. 5B, the sound absorbing member (1, 13, 14) is the same as that shown in FIG. 5A, and the clip 16 is provided at a position other than the peripheral end portion of the sound insulating material 17 in which a plurality of concave cavities are formed.
It is fixed by. FIG. 5C also shows the sound absorbing member (1,
13 and 14) are the same as those shown in FIG. 5A, and a sound insulation material 1 in which a plurality of voids are formed by blow molding a synthetic resin
It is fixed to 7 '.

FIG. 5D shows a sound absorbing material 1 similar to that shown in FIG. 3B.
And the surface material 7'is fixed to the sound insulation material 15 similar to that shown in FIG. 5A with a clip. FIG. 5E shows a sound insulating material 18 in which a hollow portion and a recess are formed by blow molding synthetic resin,
The melamine resin foam 1 is fitted and attached to the recess with the surface material 13 as the outside. FIG. 5F shows a modification 19 of the sound insulation material of FIG. 5E. Although the melamine resin foam has a flat plate shape in the above figures, it can be formed into a predetermined shape by hot pressing or the like. Further, it is possible to prevent the permeation of fats and oils and water by sealing the necessary parts with an appropriate surface material. The surface material with a thickness of 100 μm or less is the mainstream.
5 shows the thickness of the surface material in an enlarged manner.

Next, a test example of the sound absorbing material will be described.
As for the sound insulation material, the mass law is known, and it is known that the hollow double wall and the back air layer have excellent sound insulation performance.
Only the sound absorption characteristics of the sound absorbing material are tested, and the measurement method is the reverberation room method sound absorption coefficient measurement method (JIS-A14 of Japanese Industrial Standards).
09).

FIG. 8 shows the sound absorption coefficient against frequency of the example and the comparative example A. Table 1 shows the materials of the example and the comparative example A. FIG. 8 compares the sound absorbing material melamine resin foam (10 mm thick) and the glass wool (12 mm thick). In the example, there is a difference between the nylon 6 film as the surface material and the glass fiber reinforced aluminum foil. , All of which have a frequency of 1 KHz to 2 KH from the glass wool of Comparative Example A.
It is shown that the sound absorption coefficient is remarkably excellent in the range of z.

[0017]

[Table 1]

FIG. 9 shows the sound absorption coefficient of Comparative Examples B, C and D against frequency, and Table 2 shows the materials of Comparative Examples B, C and D. In Comparative Examples B and C, a melamine resin foam as a sound absorbing material has a thickness of 20 mm, and a surface material is a nylon 6 film and a glass fiber reinforced aluminum foil. The peak of sound absorption coefficient is frequency 1kHz
It shifts to the low frequency side from the range of up to 2 KHz and is inferior in sound absorption performance. In Comparative Example D, the sound absorbing material is made of glass wool having a thickness of 20 mm, and the sound absorbing coefficient has a peak in the frequency range of 1 KHz to 2 KHz, which is desirable. However, as the sound absorbing material, the thickness is large and the space efficiency is poor. Also, it is not suitable because it becomes heavy.

[0019]

[Table 2]

FIG. 10 shows sound absorption coefficients of the examples and the comparative examples E, F and G with respect to frequency, and Table 3 shows the materials of the examples and the comparative examples. FIG. 10 is for comparison by changing the thickness of the melamine resin foam, and in the examples, and have thicknesses of 5 mm, 10 mm and 15 mm, respectively. It has a frequency in the range of 1 KHz to 2 KHz and is excellent as a sound absorbing material. Comparative examples E, F, and G have respective thicknesses of 18 mm, 20 mm, and 25 mm, and the peak of the sound absorption coefficient is 1 KHz to 2 KH as the thickness increases.
It shows that the performance as a sound absorbing material is deteriorated by shifting from the z range to the low frequency side.

[0021]

[Table 3]

FIG. 11 shows examples and comparative examples H and J.
The sound absorption coefficient with respect to frequency is shown in Table 4, and the materials of Examples and Comparative Examples are shown in Table 4. FIG. 11 compares the thickness of the melamine resin foam and the thickness of the surface material of the nylon 6 film for comparison. In Examples, the thickness of the melamine resin foam is 10 mm and 16 mm, respectively, and the thickness of the surface material of the nylon 6 film is 20 μm and 80 μm, but the peak of the sound absorption coefficient is in the range of frequency 1 KHz to 2 KHz. In Comparative Examples H and J, the thickness of the melamine resin foam is 20 mm and the thickness of the surface material is changed, but the peak of the sound absorption coefficient is 1 KHz to 2 KH in both cases.
It shifts from the z range to the low frequency side.

[0023]

[Table 4]

From the above test, the thickness of the melamine resin foam having the peak of the sound absorption coefficient in the frequency range of 1 KHz to 2 KHz is in the range of 5 mm or more and less than 18 mm, and the influence of the thickness of the nylon 6 film surface material is It turns out that there are relatively few.

[0025]

INDUSTRIAL APPLICABILITY The present invention uses melamine resin foam as a sound absorbing material to obtain excellent sound absorbing properties, reduce thickness and weight, and coat the melamine resin foam with a suitable oil-repellent and water-repellent surface material. By doing so, the penetration of oils and fats can be prevented, and by using it in combination with a sound insulating material, it is possible to provide a sound insulating cover that prevents or reduces the noise of the engine or the like from leaking out of the vehicle at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a fifth embodiment of the present invention.

FIG. 6 is a conceptual diagram of a soundproof structure.

FIG. 7 is a cross-sectional view of a conventional glass wool sound absorbing material.

FIG. 8 is a graph showing the sound absorption coefficient of the first and second examples and the comparative example with respect to frequency.

FIG. 9 is a diagram showing a sound absorption coefficient with respect to frequency in a second comparative example.

FIG. 10 is a graph showing the sound absorption coefficient with respect to frequency of the third to fifth examples and the comparative example.

FIG. 11 is a diagram showing sound absorption coefficients with respect to frequency in the sixth example and the comparative example.

[Explanation of symbols]

1 Melamine resin foam 2 Surface material 3 Adhesive layer 4 Sound insulation material 5 Adhesive

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuya Matsumoto 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Isuzu Motors Limited Kawasaki Plant

Claims (3)

[Claims] 1. A sound-absorbing material, characterized in that the surface or the entire outer surface of a melamine resin foam is covered with a surface material. 2. A sound-insulating cover comprising a sound-absorbing material and a sound-insulating material in which the surface or the entire outer surface of melamine resin foam is covered with a water-repellent surface material. 3. The sound absorbing material according to claim 1, or the sound insulation cover according to claim 2, wherein the melamine resin foam has a thickness of 5 mm or more and less than 18 mm.