JP2003216161A - Acoustic material for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic material for automobiles having a high sound absorbing property in middle and high tone ranges, such as hitting sounds on the under surface of a fender section and the noise in an engine room. <P>SOLUTION: The acoustic material consists of a felt material formed by integrating fibers alone or a plurality of the fibers after blending by needle punching and flame-retardant resin layers formed by coating on both surfaces of the felt material and the layers of the fibers alone remain in the middle of the felt material, by which the high sound absorbing property in the middle and high tone ranges is imparted to the acoustic material. Also, the acoustic material consists of the felt material formed by blending at least two kinds of the fibers varying in Young's modulus, then integrating the fibers by needle punching and the flame-retardant resin layers formed by coating on one surface of the felt material and the layers of the fibers alone remain on the opposite surface of the resin layers, by which the high sound absorbing property in the middle and high tone ranges may be imparted to the acoustic material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material suitable for being attached to a lower surface of a fender portion of an automobile body or an apron side in an engine room.

[0002]

2. Description of the Related Art An automobile has many noise sources such as an engine room. By efficiently absorbing various noises generated from the automobile, a driver can enjoy quiet and comfortable touring. For example, since an engine, a fan, etc. that generate noise are installed in the engine room, it is necessary to install a sound absorbing material near the noise source. In addition, in order to mitigate the damage to the fender part and the generation of noise due to this collision, the wheel bounces up pebbles, sand, water, etc. while the vehicle is running, and collides with the fender part of the vehicle body surrounding the upper part of the wheel. It is desirable to bond a fender liner to the lower surface of the fender portion.

Conventionally, the fender liner has mainly been a molded product of high-density polyethylene, and has been selected in consideration of durability and cost, and has almost no effect of mitigating the collision sound of pebbles or sand. In order to improve this point, a foaming paint such as polyurethane or polyvinyl chloride is applied as a fender liner, or a sheet material of a thermoplastic resin such as an isotactic polyethylene resin or an ethylene-propylene-rubber copolymer. It has been proposed to use a molded product obtained by vacuum molding or stamp molding of.

On the other hand, since various parts are densely arranged in the engine room, there is very little space in which the sound absorbing material can be arranged. Therefore, the sound absorbing material is thin and heat resistant. It is necessary. As this kind of sound absorbing material, a thin non-woven fabric mainly composed of glass fibers is generally used, and it is attached after being molded into a predetermined shape.

[0005]

The glass fiber wool used as the sound absorbing material has a high sound absorption coefficient of 0.6 or more in the middle / high frequency range of 500 Hz or higher, and a frequency of 250 Hz, when the sound absorption coefficient measurement by the reverberation chamber method is referred to. In the following, the sound absorption rate drops to 0.2 or less, and at a frequency of 200 Hz, the sound absorption rate is 0.2
Worst, like 1. Although glass fiber wool absorbs about 80% of sound in the middle and high range even if it has low sound absorption in the low range where vibration reverberation is large, it is preferable for applications where this property can be utilized. As a result, it is effective to install it on the lower surface of the fender or in the engine room.

On the other hand, the non-woven sound absorbing material mainly composed of glass fibers is impregnated with a thermosetting resin because it can be molded by hot heating press. In this type of impregnated non-woven fabric, minute pores between glass fibers are often closed by the impregnating resin, and viscous resistance of air due to fibers and sound vibration damping due to vibration of the fibers themselves are reduced,
Medium frequency above about 400Hz, which is a characteristic of fiber wool
Even in the high sound range, the sound absorption property is likely to decrease, and in combination with the sound absorption property in the low sound range which is originally low, the transmission of the sound generated in the engine room cannot be suppressed so much.

On the other hand, the foaming paint used for the fender liner is not suitable as a sound absorbing material for automobiles, because the coating film is relatively thin and the collision sound of pebbles or sand is easily transmitted directly into the vehicle interior. This foaming paint has insufficient strength due to the coating film having a cell structure, and is easily damaged or peeled off by collision of pebbles or sand. Also, the molded product of the thermoplastic resin sheet material,
Even if the soundproofing performance is slightly better than that of the high-density polyethylene, the soundproofing performance as a sound absorbing material for automobiles is not sufficient because the absorption of collision sounds is still small.

The present invention has been proposed in order to improve the conventional problems relating to the sound absorbing material for automobiles, and has a high sound absorbing property in the middle and high sound ranges such as the collision sound of the lower surface of the fender and the noise in the engine room. The purpose of the present invention is to provide a sound-absorbing material for automobiles having properties. Another object of the present invention is to provide a sound absorbing material for automobiles, which has a good sound absorbing property from the low sound range to the middle and high sound ranges and is relatively inexpensive.

[0009]

In order to achieve the above object, a sound absorbing material for an automobile according to the present invention comprises a felt material obtained by mixing a single fiber or a plurality of fibers and then integrating them with a needle punch, and the felt material. And a flame-retardant resin layer coated on both sides of the material. This sound absorbing material imparts a high sound absorbing property in the middle / high range by leaving the fiber single layer in the middle of the felt material, and can be molded into a desired three-dimensional shape by hot pressing at a predetermined temperature.

In the sound absorbing material, the felt material is
It is preferable that the polyester fiber and the polyolefin fiber are mixed and then integrated by needle punching. The fiber single layer existing in the middle of the felt material preferably has a large number of fine pores and has a thickness of 1 mm or more.

The sound absorbing material for automobiles of the present invention comprises a felt material in which at least two kinds of fibers having different Young's moduli are mixed and then integrated by needle punching, and a flame-retardant resin layer coated on one side of the felt material. And may have. This sound absorbing material imparts a high sound absorbing property in the middle / high range by leaving the fiber single layer on the surface opposite to the resin layer in the felt material, and can be molded into a desired three-dimensional shape by hot pressing at a predetermined temperature.

In the sound absorbing material, the felt material is
It is preferable that the polyester fiber and the polyolefin fiber are mixed and then integrated by needle punching. The fiber single layer present on the opposite side of the resin layer in the felt material is
Preferably, it has a large number of fine holes and has a thickness of 2 mm or more.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The sound-absorbing material 1 of the present invention has a structure in which the felt material 2 is coated with thin flame-retardant resin layers 3 and 3 as shown in FIG. The flame-retardant resin layer 5 may be coated on one surface of No. 2. In either configuration, it is necessary that the fiber single layer 7 or 8 is present in the middle (FIG. 1) or the opposite surface (FIG. 2) of the felt material 2.

The felt material 2 is formed by needle punching card wraps made by blending single fibers or a plurality of fibers. In the felt material 2, the fibers may be mixed with each other uniformly by a known wrap forming method, and then spread and laminated, and a wrap manufactured by a method other than the card method may be used. The obtained card wrap is 50-400 pieces / cm in total using a normal locking needle.
And needle punching and felting with ² needle density, obtained thickness 3.0～6.0Mm, the felt material 2 weighing 500 to 1000 g / ^{m 2.}

The main fibers used for the felt material 2 are required to be relatively hard and heat resistant fibers. Examples of the main fiber include polyester fiber, rayon fiber, nylon 66 fiber, aromatic polyamide fiber, acrylic fiber, acetate fiber, fluorine fiber and the like, and polyester fiber is preferable from the viewpoint of physical properties and cost. In the felt material 2, it is preferable to color each fiber in black, gray or the like in order to improve weather resistance and heat resistance of the mixed cotton fiber.

The felt material 2 may be composed of the main fibers alone, or may be a mixture of the main fibers with other fibers. The other fibers have Young's modulus, that is, hardness, different from that of the main fibers, and thus impart higher sound absorbing property than that of the single fiber in the middle and high range. For example, the other fiber is a polyolefin fiber such as polypropylene fiber or polyethylene fiber when the main fiber is a polyester fiber or rayon fiber, and a higher Young's modulus polyester fiber when the main fiber is a fluorine fiber, Polyolefin fibers such as rayon fiber, acrylic fiber, polypropylene fiber and polyethylene fiber. The amount of other fibers added is generally 30% by weight or more, and if the amount is less than 30% by weight, the effect of imparting higher sound absorption in the middle and high range is small.

On the other hand, the flame-retardant resin layers 3 and 5 are made of an acrylic resin such as methyl methacrylate, methyl acrylate, or butyl acrylate, which is mainly produced by emulsion polymerization.
It is preferable to use latex of methacrylonitrile, styrene, PVC or the like, which has a relatively high viscosity to prevent it from penetrating into the felt material 2 during coating. For the flame-retardant resin layer, a reactive polymer that is crosslinked by heat treatment to form a three-dimensional network may be used in order to make the hardness relatively high and enhance the sound absorbing property in the low tone range. A suitable amount of flame retardants such as phosphoric acid ester, antimony oxide, zinc borate, chlorinated paraffin and ethylene tetrabromide is added to these latexes.

By making the flame-retardant resin layer 3 or 5 have a relatively high hardness, it is possible to configure a resonance system in which the single fiber layers 7 and 8 are air layers, and sound in the low frequency range around 200 Hz is converted into thermal energy. Sound can be effectively absorbed by changing it. Here, the flame-retardant resin layer 3 or 5 is a resonance system in which the mass is the air and the air in the fiber single layers 7 and 8 is the spring. Therefore, it is preferable that the flame-retardant resin layer is hard and heavy to some extent.

As shown in FIG. 1, the flame-retardant resin layers 3, 3
If both are formed on both sides of the felt material 2, the intermediate fiber single layer 7 maintains sound absorption in the middle and high range,
Sound in the low frequency range can be absorbed by the flame-retardant resin layers 3 and 3 and the air layer between both resin layers. When the intermediate fiber single layer 7 has a thickness of 1 mm or more, it is preferable because the single fiber layer can impart high sound absorption in the middle and high range, and when the thickness is less than 1 mm, the sound absorption in the middle and high range is achieved. It drops considerably. The weight of the flame-retardant resin layer 3 is 100 to 250 g / m ² or more per one side, and within this range, the sound absorbing property is exhibited even in the low sound range. A black pigment or the like is preferably added to the flame-retardant resin layer 3 in order to improve weather resistance and heat resistance. Since the sound absorbing material 1 shown in FIG. 1 is in a mode in which the fibers of the intermediate fiber single layer 7 are bound by the flame-retardant resin layers 3 and 3 on both sides, the lighter the harder the flame-retardant resin layers 3 and 3, the lighter the weight. It has a high damping effect to effectively damp the vibration of.

Further, as shown in FIG. 2, if the flame-retardant resin layer 5 is formed on one side of the felt material 2, while the sound absorbing property in the middle and high range is maintained by the fiber single layer 8 on the opposite side. The noise in the low range can be absorbed by the flame-retardant resin layer 5 and the air layer behind the resin layer. When the fiber single layer 8 has a thickness of 2 mm or more, it is preferable because the fiber single layer provides high sound absorption in the middle and high range, and when the thickness is less than 2 mm, the sound absorption in the middle and high range is considerably achieved. Will fall. The weight of the flame-retardant resin layer 5 is 100 to 250 g / m ² , and within this range, the sound absorbing property is exhibited even in the low sound range. Since the sound absorbing material 10 shown in FIG. 2 is in a mode in which the fibers of the single fiber layer 8 are not constrained by the flame-retardant resin layer 5, the damping effect of damping the vibration of the lightweight object is relatively small.

The sheet-shaped sound absorbing material is attached to the lower surface of the fender portion 12 or the engine room (not shown) of the automobile as illustrated in FIG.
It is necessary to heat press at a temperature of about 0 ° C. to form a desired three-dimensional shape as shown in FIG. This molding process may be carried out by directly hot pressing the sheet-shaped sound absorbing material, or heat-setting the sound absorbing material at a desired temperature and then cold pressing. Due to the presence of the flame-retardant resin layers 3 and 5, the sound absorbing material can be accurately molded into a desired three-dimensional shape by hot pressing.

This sound absorbing material has a high sound absorbing property in the middle and high range due to the presence of the single fiber layers 7 and 8, and also absorbs low range noise by the flame-retardant resin layers 3 and 5 and the enclosed air. As a result, the sound absorbing characteristics are good over almost all frequencies of the audible sound, and the fender liner 14 (FIG. 3) and the sound absorbing material for the engine room have a high sound insulating performance, that is, a sound insulating effect. This sound absorbing material is easily formed into a three-dimensional shape due to the presence of the flame-retardant resin layers 3, 3 or 5, and is less likely to undergo thermal deformation and dimensional change during the molding process, and can be fitted to the lower surface of the fender portion 12 or the engine room, Wrinkles can be avoided at the corners.

The sound absorbing material 1 shown in FIG. 1 is in a cardboard-like mode in which the fibers of the intermediate fiber single layer 7 are constrained by the flame-retardant resin layers 3 and 3 on both sides. 7
By relying on the shear deformation of, it has higher rigidity and shape retention than ordinary felt materials and resin sheets. Therefore, the sound absorbing material 1 is superior to the conventional product in mechanical properties such as abrasion resistance and tensile strength even in a severe use environment.

The sound absorbing material of the present invention comprises a felt material 2 made of a thin thermoplastic fiber and a flame-retardant resin layer 3, 3 or 5.
If desired, it is possible to interpose a base fabric such as a very thin spunbonded non-woven fabric. The sound absorbing material of the present invention can be recycled when the attached vehicle is discarded and incinerated, and no toxic gas such as chlorine gas which is a pollution source is generated, and sewing machine sewing such as overlock is temporarily performed. The surroundings will not be torn.

[0025]

EXAMPLES Next, the present invention will be explained based on examples, but the present invention is not limited to the examples.

Example 1 To manufacture the sound absorbing material 1 shown in FIG. 1, 60 wt% of 6-denier black polyester and 60 wt% of 3-denier black polypropylene fiber were used as the felt material 2, and these were mixed with each other. -Laminate to obtain card wrap. This card wrap 1
Felt by needle punching with a needle density of 50 needles / cm ² . The felt material 2 obtained has a thickness of about 4.0 m.
m, and the weight is 600 g / m ² .

One side of the felt material 2 is coated with 200 g / m ^{2 of} a flame-retardant acrylic resin (trade name: Acronal, manufactured by Mitsubishi BASF) containing a black pigment and dried. Next, the felt material 2 is turned over, and the same flame-retardant acrylic resin is further coated at 200 g / m ² and dried. The obtained sound absorbing material 1 has a thickness of about 4.0 mm and a weight of 100.
Was 0 g / ^{m 2,} about 1.5mm each thickness of the flame-retardant resin layer 3,3, the thickness of the fiber alone layer 7 is about 1 mm.

The sheet-shaped sound absorbing material 1 is put in a heating furnace (not shown), heated at about 200 ° C. for 3 minutes, cold pressed, and then trimmed appropriately to manufacture the fender liner 14 (FIG. 3). Fender liner 14
Is a three-dimensional shape that fits the lower surface of the fender portion 12,
The whole has elongated, generally arcuate sides. The fender liner 14 has a vertical semi-circular cutout portion 15 formed in the center thereof, and has a small diameter clip hole 1 in both shoulders of the liner.
A large number of 7, 17 are provided.

As shown in FIG. 4, the fender liner 14 is fixed to the lower surface of the fender portion 12 of the vehicle body by a large number of clip pins (not shown). The fender liner 14 covers the upper portion of the wheel 20, and a suspension shaft (not shown) penetrates through the cutout portion 15.

The fender liner 14 maintains the sound absorbing property in the middle and high range by the intermediate fiber single layer 7, while the noise in the low range is relatively hard, and the air between the resin layers 3 and 3 and both resin layers is relatively hard. Can effectively absorb sound with layers. Fender liner 1
No. 4 prevents damage to the fender portion 12 due to these collisions even if the wheels bounce up pebbles, sand, water, etc. while the vehicle is traveling, and alleviates the noise that echoes inside the vehicle.

Example 2 In order to manufacture the sound absorbing material 10 shown in FIG. 2, as the felt material 2, 60% by weight of black polyester having 6 denier and 40% by weight of black polypropylene fiber having 3 denier are used,
These are mixed and laminated with each other to obtain a card wrap. This card wrap is made into a felt by needle punching at a needle density of 200 needles / cm ² using a normal locking needle. The felt material 2 obtained has a thickness of about 4.0.
mm, and the weight is 700 g / m ² .

One side of the felt material 2 is coated with the flame-retardant acrylic resin used in Example 1 at 150 g / m ² and dried. The obtained sound absorbing material 10 has a thickness of about 4.0 mm,
The weight is 850 g / m ² , the thickness of the flame-retardant resin layer 5 is about 1.2 mm, and the thickness of the single fiber layer 8 is about 2.8 mm.

The sheet-shaped sound absorbing material 10 includes the fiber single layer 8
Is set on the outer side, and hot pressed at about 180 ° C. for 3 minutes, and then a fender liner is manufactured by appropriate trimming. This fender liner has a three-dimensional shape that conforms to the lower surface of the fender portion of the vehicle body, and has a slender and substantially arcuate side surface as a whole.

In the molded fender liner, the single fiber layer 8 is located outside. In this fender liner, a single fiber layer 8 is sandwiched between the fender portion and the flame-retardant resin layer 5 by being fixed to the lower surface of the fender portion 12 of the vehicle body with a large number of clip pins. This fender liner effectively retains the sound absorbing property in the middle / high range by the single fiber layer 8 and effectively uses the flame-retardant resin layer 5 and the air layer behind the resin layer which are relatively hard in the low range noise. Can absorb sound.

Example 3 To manufacture the sound absorbing material 10 shown in FIG. 2, 70 wt% of 6-denier black polyester and 30 wt% of 3-denier black polypropylene fiber were used as the felt material 2.
These are mixed and laminated with each other to obtain a card wrap. This card wrap is made into a felt by needle punching at a needle density of 200 needles / cm ² using a normal locking needle. The felt material 2 obtained has a thickness of about 4.0.
mm, and the weight is 700 g / m ² .

One side of the felt material 2 is coated with the flame-retardant acrylic resin used in Example 1 at 150 g / m ² and dried. The obtained sound absorbing material 10 has a thickness of about 4.0 mm,
The weight is 850 g / m ² , the thickness of the flame-retardant resin layer 5 is about 1.2 mm, and the thickness of the single fiber layer 8 is about 2.8 mm.

The sheet-shaped sound absorbing material 10 is hot-pressed at about 180 ° C. for 3 minutes and then subjected to appropriate trimming to manufacture a fender liner. This fender liner has a three-dimensional shape that conforms to the lower surface of the fender portion of the vehicle body, and has a slender and substantially arcuate side surface as a whole. This fender liner is attached to the lower surface of the fender portion of the vehicle body similarly to the first embodiment, and has substantially the same soundproofing performance as that of the second embodiment.

[0038]

EFFECTS OF THE INVENTION The sound absorbing material according to the present invention has a high sound absorbing property in the middle and high range by the fiber single layer remaining on the middle or one side, and the noise in the low range is also effective in the flame-retardant resin layer. By absorbing the sound, the sound absorbing characteristic is good over almost all frequencies of the audible sound. Therefore, the sound absorbing material of the present invention has higher sound absorbing characteristics than the conventional sound absorbing material containing glass fiber as a main component and is lighter than the conventional sound absorbing material made of glass fiber.

In the sound absorbing material of the present invention, if a felt material in which at least two kinds of fibers having different Young's moduli are mixed is used, it is possible to impart a higher sound absorbing property than a single fiber in the middle and high range. In particular, the sound absorbing material coated with a flame-retardant resin layer on both sides is a cardboard-like mode in which the fibers of the intermediate fiber single layer are constrained by the flame-retardant resin layers on both sides, and the fiber single layer is applied against the applied pressure. By relying on the shear deformation of, it has higher rigidity and shape retention than ordinary felt materials and resin sheets. Therefore, the sound absorbing material of the present invention is superior in mechanical properties such as abrasion resistance and tensile strength to the conventional sound absorbing material in a severe environment of use.

The sound absorbing material of the present invention is composed of only thermoplastic fibers and flame-retardant resin, and can be sufficiently recycled as an automobile part. Therefore, the sound absorbing material of the present invention is preferable in that it can reuse resources on the earth, and is economical in that it can be recycled, as compared with the sound absorbing material mainly composed of glass fibers.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a sound absorbing material for an automobile according to the present invention.

FIG. 2 is a schematic sectional view showing a modified example of the present invention.

FIG. 3 is a schematic perspective view showing an example of a fender liner manufactured from the sound absorbing material of the present invention.

FIG. 4 is a cross-sectional view of relevant parts schematically showing a state in which the fender liner of FIG. 3 is attached to a fender portion of a vehicle body.

[Explanation of symbols]

1 sound absorbing material 2 felt material 3,3 Flame-retardant resin layer 5 Flame-retardant resin layer 7 Fiber single layer 14 Fender Liner

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) D04H 1/42 D04H 1/46 Z 1/46 G10K 11/16 A G10K 11/172 EF term (reference) 3D003 AA07 BB01 CA03 CA63 DA03 3D023 BA02 BA03 BB21 BD21 BE04 BE31 4F100 AK03A AK03B AK03C AK07 AK25 AK41A AK41B AK41C BA03 BA10B BA10C CA13 DG15A DG15B DG15C DG18A DG18B DG18C DH02B DH02C EC09A EC09B EC09C GB32 JH01 JJ07B JJ07C JK07A JK07B JK07C JK09 JL01 JL04 JL16 YY00A 4L047 AA14 AA21 AA28 AB02 BA03 CA07 CB01 CB03 CB04 CC09 5D061 AA06 AA22 AA25 BB02 BB24 DD04 DD11

Claims (4)

[Claims] 1. A felt material comprising a single material or a plurality of fibers mixed together and then integrated by needle punching, and a flame-retardant resin layer coated on both sides of the felt material. A sound absorbing material for automobiles, which has high sound absorbing properties in the middle and high frequencies due to the remaining layer, and can be molded into a desired three-dimensional shape when heated and pressed at a predetermined temperature. 2. A felt material obtained by mixing polyester fibers and polyolefin fibers together with a needle punch, and a flame-retardant resin layer coated on both sides of the felt material. A single layer of fibers with a thickness of 1 mm or more, which has a large number of pores, has a high sound absorbing property in the middle and high range, and can be molded into a desired three-dimensional shape by hot pressing at high temperature. 3. A felt material obtained by mixing at least two kinds of fibers having different Young's moduli and then integrated with a needle punch, and a flame-retardant resin layer coated on one side of the felt material. A sound absorbing material for automobiles, which has a single fiber layer remaining on the opposite side of the layer, imparts high sound absorbing properties in the middle and high frequencies, and can be molded into a desired three-dimensional shape by hot pressing at a predetermined temperature. 4. A felt material comprising polyester fibers and polyolefin fibers mixed with each other and then integrated by needle punching, and a flame-retardant resin layer coated on one side of the felt material, the felt material being opposite to the resin layer. A single layer of fibers with a thickness of 2 mm or more, which has a large number of fine pores on the surface, gives high sound absorption in the middle and high frequencies, and can be molded into a desired three-dimensional shape by hot pressing at high temperature. Sound absorbing material.