JPS59186750A - Sound absorption panel for automobile hood - Google Patents

Abstract

PURPOSE:To prevent the noise of an engine from being transmitted, by press- forming a prescribed bulky nonwoven fabric and providing a skin on the fabric to obtain a sound absorption panel whose bulk density and air flow resistance are set in prescribed ranges and by mounting the panel so that an air layer is defined between the panel and a hood. CONSTITUTION:A bulky nonwoven fabric is press-formed from one or plural kinds of discontinuous-fiber material and a synthetic resin. A skin is provided on one or both sides of the fabric. The bulk density and air flow resistance of the fabric with the skin are set at 0.05-0.66g/cm<3> and 30-300C.G.S.RAYLS, respectively. After the fabric with the skin is cut to an appropriate shape, the fabric with the skin is mounted so that an air layer is defined between the fabric and a hood. A sound absorption panel for the hood is thus provided. The discontinuous-fiber material derives from animals, plants, minerals, synthetic resins or the like. The skin is a thin nonwoven fabric of good appearance and high resistance to water and oil, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile headphone hood absorbing plate, and more particularly to a sound absorbing plate for an automobile hood, and more particularly to an extremely remarkable sound absorbing plate that reduces noise inside and outside the vehicle through a sound absorbing process in the engine compartment. This invention relates to a sound-absorbing board for a bonnet foot that can realize the effects.

Conventionally, measures have been taken to prevent engine noise from propagating into the passenger compartment, such as installing sound insulating pads on the dash, and preventing the transmission of vibration through the floor panels by not using damping materials. However, such methods alone are still insufficient as a measure against vehicle interior noise, and can hardly contribute to measures against vehicle exterior noise, which has recently become a social problem.

As a sound absorbing treatment method for an engine compartment, it is known to adhere or attach a sound absorbing material to the back surface of the hood. For example, the earliest attempts were to attach urethane foam or cut pieces of glass fiber cotton with an adhesive, and attempts were made to externally pressure-form bulky glass fiber cotton into a predetermined shape (1986-1985).
981) is known.

Attempts to attach urethane ohms were made in the first issue of Q Koyori 1.
A number of finely cut fish are placed on the divided bonnet base.
Due to the complicated process of attaching different types of urethane foam, it is difficult to control the size and number of bubbles during the production of urethane foam, resulting in stable sound absorption performance.

Furthermore, it is inferior in heat resistance and is currently hardly used in practical use.

According to Japanese Utility Model Publication No. 52-56981, glass fiber cotton is made of high-density reinforcing parts that fit into the framework of the bonnet, while other parts have low-density, and one surface of the low-density part is provided with many uneven parts, and Sound absorbing materials with a skin attached to them have been proposed. In this proposal, it is recommended to use the low-density bulky part as it is as the sound-absorbing part. There is no mention of whether air flow resistance should be selected or not. Furthermore,
This proposal has the drawback of irritating the skin, and requires the use of highly densely compressed parts that fit the frame, so sound-absorbing materials with different shapes are produced for each car model. In addition, new molds must be made for each car model and each time the model is changed.

There were complex problems in terms of production, management, and costs, including high mold production costs. However, the above-mentioned problem becomes extremely serious especially when the number of vehicle types increases dramatically.

The present inventor has continued research in order to provide a sound absorbing board that satisfies these demands for a sound absorbing material to be attached to the back surface of a bonnet hood.

As a result, the entire surface is almost uniform, which is completely different from the sound-absorbing material, which is a sound-absorbing board with a specific bulk density and air flow resistance and has a bulky sound-absorbing part that reaches the bonnet base recommended in Utility Model Publication No. 52-56981. The compressed sound-absorbing plate becomes a sound-absorbing material that conveniently satisfies the above requirements.
It was also discovered that the sound-absorbing plate is a flat plate and can exhibit sound-absorbing properties in any part, so it can be used in any car make or model.

Furthermore, the flat sound-absorbing board, combined with the back air layer between it and the main body of the phone, can achieve sound-absorbing properties that exceed that of conventional bulky sound-absorbing materials. It was discovered that a sound-absorbing board for a boxwood net hood could be made by simply cutting the material and punching a clear hole for installation using a leather punch or cork bowler.

Therefore, it is an object of the present invention to provide a sound absorbing board for a telephone hood that achieves the above-mentioned improvements.

First, the gist of the present invention is as follows.

A bulky nonwoven fabric made of one or more discontinuous fiber materials and a synthetic resin is compression molded, has a skin on one or both sides, and has a bulk density of 0, 05 to 0.
．． 669r7ctx.

Air flow resistance is 30-300C, G, S.

A sound absorbing board for a bonnet hood, which is a RAYLS sound absorbing board, characterized in that it is cut into an appropriate shape and then installed with an air layer provided between it and the bonnet base.

It is in.

Later, as shown experimentally by giving examples and comparative examples, it is difficult to achieve the excellent improvement of the present invention by using a sound absorbing plate that does not satisfy either the bulk density or air flow resistance.

The present invention is fundamentally based on a sound absorption treatment method that seeks to obtain an effect by providing a rear air layer.

The principle is already known. However, a method that can be easily used even by the owner/driver of a car by applying this principle to the limited volume of the engine compartment has not yet been considered, As a sound-absorbing measure, it has only been proposed to apply a glass wool mat to the entire back of the bonnet hood with adhesive.

According to the present invention, the frame of the bonnet, which has a reinforced structure, is effectively used during installation, and the height of the frame is effectively used as a rear air layer, and can be applied to any type of automobile. This makes it possible to reduce noise.

The bulky nonwoven fabric used in the present invention is mainly composed of a binder made of one or more of animal, vegetable, mineral, and synthetic resin discontinuous fiber materials and a synthetic resin, and is itself known in the art. However, if the bonding material is a thermosetting resin, it is in an uncured state before heating and compression molding, and furthermore, it can be obtained by melting the thermosetting resin or using a thermoplastic resin together, etc. By other means, industrial wastes such as bulky cotton wool, waste cotton, and synthetic fiber waste can be used economically.

In this state, the bulky nonwoven fabric preferably has a thickness of 15 to 50 rtr and an areal density of 400 to 200,037 rtr.

In the present invention, an excellent sound absorption effect can be obtained even if the bulky nonwoven fabric is heat-formed as it is, but it is also possible to use it by heat-forming it after pasting a non-flammable or non-combustible thin nonwoven fabric, or It is absolutely preferable to use heat molding after applying a flame retardant, etc., or heat molding and applying #& flame retardant treatment agent 9 anti-fuzzing agent, etc. . In order to make (1) flammable or non-flammable, the content of mineral fibers such as glass fibers and carbon fibers may be increased, or a flammable phenol resin may be used as a binder. It is also effective to apply waterproofing, and even when such treatment is applied, the bulk density of the sound absorbing plate after treatment is 0.05 to 0.66"/cJ, the air flow resistance is 30 to 300 C, It is an essential requirement that it be within the range of G, S, and RAYLS.

In the present invention, the skin provided on one or both sides of the sound-absorbing plate imparts water resistance and oil resistance, and is also an essential requirement from an aesthetic point of view. , synthetic fibers with high softening points are used. As the synthetic fibers used for the fleece, polyester fibers, polyamide fibers, acrylic fibers, etc. are used. The binder used in the fleece is:

Preferably, the thermoplastic resin having a softening point of 100° C. or higher is used as the main component, and the thermosetting resin is preferably mixed in an amount equal to or less than that of the resin.

The skin described above is laminated on one or both sides of a bulky nonwoven fabric and molded under heat and pressure, and the temperature during molding is 150 to 230°C.
A molding time of about 15 to 300 seconds is sufficient. A pressure of 100 mm or less during molding is sufficient.

The sound absorbing plate of the present invention obtained by these molding processes has a thickness of 3 to 10.
! The sound absorbing board is compression molded to a thickness of Im, but the most important thing in obtaining the sound absorbing board is that the bulk density is 0゜(1
If the bulk density is smaller than 0.05 and is too bulky, there is a risk of dry contact, which is undesirable.If the bulk density is larger than 0.66, which results in an excessively dense port shape, air permeability is lost and sound absorbing properties cannot be realized at all, which is not preferable.

Air flow resistance is an important factor governing the sound absorption properties of porous sound absorbing materials.5 In the present invention, air flow resistance is 30
If the air flow resistance is smaller and the air permeability is higher, the sound absorption property will be significantly lowered, and if the air flow resistance is greater than 300 and the air permeability is lacking, no sound absorption property can be expected.

The sound absorbing board according to the present invention is cut into an appropriate shape and then
Although it is attached to the back side, it is essential to provide an air layer between it and the bonnet base, and it is preferable to provide an air layer of 5 to 40 degrees. If the air layer is less than 5M, the peak frequency of the sound absorption coefficient will be in a high frequency range, which is not practical as a noise countermeasure for the engine storage area. Also 40III
If it exceeds I+, it is common that it becomes structurally difficult to remove.

The sound absorption coefficient peaks in the low frequency range, making it difficult to put it to practical use. For example, it is easiest to use a skeleton height of about 10-30 mm. It may also be attached during installation.

If there are no holes in the frame, use a drill or the like to make holes at appropriate locations.

If there is no hole or narrow hole in the frame that can be used as a foothold for installation, the bonnet base should have a height of about 10 to 30 dragons,
A bracket supporting a hole with a diameter of about 5 to 10 dragons may be directly attached, and a sound absorbing plate may be attached to the bracket. Even if there are holes or narrow holes in the frame that can be used as scaffolding, 101
If the above is too large.

An auxiliary board having holes of 5 to 10 diameters may be attached and used. When using the bracket 1 or an auxiliary board, you may use one that has been threaded so that screws can be used.

Furthermore, it may be directly attached to the frame with an adhesive.

The clip used for attachment may be any conventionally known clip, such as a bush type, a plunger quive, a Christmas tree clip, etc.

An example of the method of mounting the sound absorbing plate of the present invention is as follows.

Place a transparent sheet or film on the back of the bonnet hood and mark the frame and hole positions. Next, place the film on the sound absorbing board of the present invention and temporarily secure it with cellophane tape, punch 8 to 10 holes directly from the bottom of the film with a weeding punch, and then cut the outer periphery with a utility knife in a shape that roughly follows the frame. Cut it out. The obtained sound absorbing plate may be attached with a clip.

Examples are given below to provide a more detailed understanding of the present invention.

Naturally, the present invention is not limited to the following examples.

Example 1 30 parts by weight of recycled wool and 50 parts by weight of fallen cotton were opened and mixed, and the melting point was 1.
Phenolic resin powder 2 with reaction temperature 170'c at 40°C
0 parts by weight were dispersed and mixed to form a fleece using a fleece forming machine, and then passed through a heating furnace at 150°C to obtain a bulky nonwoven having a thickness of 21i+n and an areal density of 950'T/kidney.

Bulk density 10) containing 25 parts by weight solids of acrylic resin as an adhesive binder per 100 parts by weight of fibers.
/ cJ (thickness lQmm, areal density t, oo') 7m) polyester fiber fleece (if+ name resin cotton),
The bulky nonwoven fabric was laminated on both sides.

Then, the sound absorbing plate of the present invention was obtained by pressure molding for 1 minute under heating conditions of 200°C. The thickness of the obtained sound absorbing plate is 5
mm, bulk density was t+, 197/cj air flow resistance was 132 C,G,S,RAYLS.

The frame of the phone and the film with the clip holes marked in advance were placed on the sound absorbing board obtained in Example 1 and temporarily fixed with cellophane tape, and 81 holes were punched directly on the film using a weeding punch, and then almost the frame was removed. The outer periphery was cut with a cutter knife in the shape of , and the resulting sound absorbing plate was attached to the frame using clips. The height of the frame was about 25 mm, and the distance between the sound absorbing plate and the curved bonnet hood base was between about 22 and 28 mm.Example 2: 30 parts by weight of recycled wool, 25 parts by weight of fallen cotton, 30 parts by weight of glass fiber. Parts by weight were opened and mixed, 15 parts by weight of phenolic resin powder with a melting point of 140°C and a reaction temperature of 170°C was sprinkled and mixed, formed into a fleece using a fleece forming machine, and passed through a heating furnace at 150°C to a thickness of 18 mm and an areal density. A bulky nonwoven of 8300#/Cl1l was obtained.

A bulk density of 10'j containing 25 parts by weight of acrylic resin as an adhesive binder based on 100 parts by weight of the fiber tanka.
A polyester fiber fleece (commonly known as resin cotton) having a thickness of /c, d (thickness: 10 x 2 surface density: 100')/d) was laminated on both sides of the bulky nonwoven fabric.

Then, the sound absorbing plate of the present invention was formed by pressure molding for 1 minute under heating conditions of 200°C. The thickness of the obtained sound absorbing board is 4
+u+, and the bulk density is 0.2L'f/cJ
.

Air flow resistance was 166 C,G,S,RAYLS.

A sound absorbing plate was processed in the same manner as in Example 1 and attached to the same car hood as in Example 1. Needless to say, the distance between the sound absorbing plate and the main foot base is the same.

Example 3 One side of a glass fiber bulky nonwoven fabric with a thickness of 45 and a surface density of 100 (1')/cJ contains 25 parts by weight of acrylic resin as an adhesive binder in terms of solid content per 100 parts by weight of the fibers. Polyester fiber fleece (commonly known as resin cotton) having a bulk density of 1 [1'i/cJ (thickness: 10 parts, 9 areal density: 100), 7 m] was laminated.

Then, the sound absorbing plate of the present invention was obtained by pressure molding for 2 minutes under heating conditions of 210°C. The thickness of the obtained sound-absorbing plate was 6 fins, and the bulk density was 0.166′g/cnt.

Air flow resistance was 104 C, G, S, RAYLS.

A sound absorbing plate was processed in the same manner as in Example 1, and was attached to the hood of a car in the same manner as in Example 1. Needless to say, the distance between the sound absorbing plate and the bonnet hood base is the same.

Comparative Example 1 30 parts by weight of recycled wool, 50 parts by weight of fallen cotton (spreading and mixing, phenol resin powder 2 with a melting point of 140°C and a reaction temperature of 170°C)
After scattering and mixing 0 parts by weight to form a fleece with a fleece forming machine, it is passed through a heating furnace at 150°C to a thickness of 18 fins and a 3-sided density of 6 o.
A bulky nonwoven of oi/= was obtained.

A polyester fiber fleece (commonly known as resin cotton) having a solid content of 25 weight d) based on 100 parts by weight of the fiber type N was laminated on one side of the bulky nonwoven fabric.

Then, a sound absorbing plate as a comparative example was obtained by pressure molding for 1 minute under heating conditions of 180'C. The thickness of the obtained sound absorbing plate is 1
3), the bulk density was 0.046 i/cl, and the air flow resistance was 21 C, G, S, RAYLS.

A sound absorbing plate was processed in the same manner as in Example 1 and attached to the bonnet hood of the same automobile as in Example 1. Needless to say, the distance between the sound absorbing plate and the bonnet hood base is the same.

Comparative Example 2 30 parts by weight of recycled wool and 50 parts by weight of fallen cotton were opened and mixed, and the melting point was 1.
20 parts by weight of phenolic resin powder with a reaction temperature of 170'C was sprinkled and mixed at 40°C, formed into a fleece using a fleece forming machine, and passed through a heating furnace at 150°C to a thickness of 38 x 1 area density of 2.
A bulky nonwoven of 100'J/m was obtained.

Bulk density 10 containing 25 parts by weight of acrylic resin as an adhesive binder in solid content per part of fiber type i100ffi
)/cn+ (thickness: 10 tuna, surface density: 100?/m) polyester fiber fleece (commonly known as resin cotton) was laminated on one side of the bulky nonwoven fabric.

Then, it was pressure-molded for 2 minutes under heating conditions of 220° C. to obtain a sound absorbing plate as a comparative example. The thickness of the iM sound absorbing board is 3
It is a dragon, and its bulk density is 0.70'7/c♂.

Air flow resistance was 340 C,G,S,RAYLS.

A sound absorbing plate was processed in the same manner as in Example ①, and was attached to the bonnet hood of a car in the same manner as in Example 1. Needless to say, the distance between the sound absorbing plate and the bonnet hood base is the same.

Comparative Example 3 The sound-absorbing plate obtained in Example 1 was cut into a size 11 using a framework, and directly attached to a Bonnet-nod hood substrate G with an adhesive.

Comparative Example 4 Bulk density force with aluminum foil on one side <0.0251
/ cJ "?'A commercially available sound absorbing N4 was attached directly to the Honne Nodo hood base with an adhesive.

When the sound absorption coefficients of these materials were determined using the reverberation room method G611, the following results were obtained.

It has become clear that a sound absorption effect can be realized.

Patent applicant: Japan Special Paint Co., Ltd.

Claims (1)

[Scope of Claims] A bulky nonwoven fabric made of one or more discontinuous fiber materials and a synthetic resin is compression molded, has a skin on one or both sides, and has a bulk density of 0.05. ~0.6
6/Ca. Air flow resistance is 30-300C, G, S. A sound absorbing board for a bonnet hood, which is a RAYLS sound absorbing board, characterized in that it is cut into an appropriate shape and then installed with an air layer provided between it and the bonnet base.