JP3400658B2 - Sound insulation cover for vehicles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound insulation cover for a vehicle that reduces noise generated from equipment mounted on the vehicle.

[0002]

2. Description of the Related Art Conventionally, a vehicle such as a truck equipped with a diesel engine is equipped with a sound insulating cover in order to prevent noise generated by the engine and its reflected sound from leaking out of the vehicle. As such a sound insulation cover, as shown in FIG. 3, a rigid member 5 made of an iron plate or the like attached to the vehicle body frame 4, a urethane foam layer 6 fixed to the rigid member 5, and a surface of the urethane foam layer 6 are covered. It is known to be composed of a skin material 7 made of a polyurethane film or the like.

[0003]

The urethane foam constituting the urethane foam layer is preferably used because it has excellent sound absorbing properties, and is usually formed by using polyether polyol. However, since such urethane foam has a high water absorption rate, when it is used in a portion that is in contact with rainwater or the like like the above sound insulation cover, it absorbs water to increase the mass and deteriorate the durability of the sound insulation cover. Problems such as occur. Therefore, in the above conventional sound insulation cover, the skin material 7 is attached in order to prevent water absorption of the urethane foam layer 6.

However, since the skin material 7 such as a polyurethane film has a poor sound absorption property as compared with urethane foam, the skin material 7 arranged so as to cover the surface of the urethane foam layer 6 has an excellent sound absorbing performance. Is hindered.
Further, since the skin material 7 is attached, the number of manufacturing steps increases accordingly, and special equipment such as a vacuuming device is required for the foaming mold, which causes a problem of increasing cost.

The present invention has been devised in view of the above circumstances, and it is an object to be solved to provide a sound insulation cover for a vehicle, which is capable of further improving the sound absorbing property by eliminating the skin material. Is.

[0006]

The invention according to claim 1 for solving the above-mentioned problems is a sound insulation cover for a vehicle, comprising a plate-shaped rigid member and a urethane foam layer fixed to the rigid member, The urethane foam layer is formed of a foam obtained by reacting a mixture of a polyolefin polyol having a saturated hydrocarbon resin skeleton, water as a foaming agent, and an organic polyisocyanate, and the water absorption rate of the foam is 1
It is characterized by being set to 0% or less.

According to a second aspect of the present invention, in the vehicle sound-insulating cover according to the first aspect, the foam contains a surfactant whose basic skeleton is a fatty acid ester having a hydrophilic group in the chain of the mixture. It is characterized by being formed by reacting below. According to a third aspect of the present invention, in the vehicle sound insulation cover according to the first and second aspects, the surface of the urethane foam layer is an uneven surface having a grain pattern.

According to a fourth aspect of the present invention, in the vehicle sound insulation cover according to the first to third aspects, the rigid member is
At least one side has a mounting portion, and the other side is an open end.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the rigid member in the present invention, a member formed of a metal plate, a hard resin plate or the like can be used. The rigid member may have a mounting portion mounted on the vehicle at least on one side in accordance with a mounting position of the sound insulation cover, and may be configured such that the other side has an open end.

The urethane foam layer in the present invention is formed of a foam obtained by reacting a mixture of a polyolefin polyol having a saturated hydrocarbon resin skeleton, water as a foaming agent, and an organic polyisocyanate. The polyolefin polyol having a saturated hydrocarbon resin skeleton means, for example, atactic butadiene oligomer as described in Chemical formula 1 or hydrogenated polybutadiene. This polyolefin polyol is
For example, it can be produced by anion-living polymerization of butadiene.

[0011]

[Chemical 1]

This polyolefin polyol preferably has a side chain and has a reactive primary hydroxyl group at the molecular end. By having a side chain, the vibration damping property of the formed foam is further improved. The polyolefin polyol preferably has a number average molecular weight in the range of 1,000 to 9000. If the number average molecular weight is less than 1000, the foam becomes hard and brittle, and if it exceeds 9000, the viscosity may be too high and foam molding may be difficult. Particularly desirable is the range of 1500 to 3000. In order to set the number average molecular weight in the range of 1000 to 9000, the hydroxyl value is preferably set to 10 to 140.

As the organic polyisocyanate, those used for urethane foam using a usual polyether polyol can be used as they are. Examples of such organic polyisocyanates include MDI type and TDI type.
Examples include systems, XDI systems, HMDI systems, IPDI systems, and the like. The present inventors conducted experiments using various surfactants in order to uniformly disperse water in the polyolefin polyol. As a result, they have found that a surfactant having a basic skeleton of a fatty acid ester having a hydrophilic group in the chain gives particularly preferable results. As this surfactant, one having an HLB value of 10 or more is preferable.

In order to introduce a hydrophilic group into the chain of a fatty acid ester, a fatty acid ester having a hydroxyl group or a double bond is used, and the hydrophilic group is substituted or added to the hydroxyl group or the double bond and introduced. it can. Typical examples of such fatty acid ester include castor oil, but not limited to castor oil, fatty acid esters such as peanut oil, olive oil, fish oil, and whale oil can also be used.

In particular, when a hydrophilic group is introduced by using a fatty acid ester having a hydroxyl group in the chain, the substitution of the hydrophilic group is facilitated and the water can be uniformly dispersed. Further, even if the hydroxyl group which is not substituted by the hydrophilic group remains, because it is integrated as a part of the foam by the reaction with isocyanate,
The foam can be made more hydrophobic and the water absorption can be greatly reduced.

The polyolefin polyol, the surfactant and the organic polyisocyanate have an NCO / OH ratio of 60 to 1
It is desirable to mix in the range of 50. NCO / O
When H is less than 60, the crosslink density is lowered, and the vibration damping property and the sound absorbing property of the obtained foam are lowered. Further, when NCO / OH exceeds 150, there arises a problem that the foam becomes brittle. Particularly desirable range is NCO / OH of 80 to 120
Is the range.

Further, it is desirable to add the surfactant in an amount of 20 to 200 parts by weight based on 100 parts by weight of water used. If the amount of the surfactant is less than 20 parts by weight, the mixing of water will be non-uniform and uniform foam molding will be difficult.
Further, even if the amount is more than 200 parts by weight, no further effect of the surfactant is exhibited. When the viscosity of the polyolefin polyol is high and foam molding is difficult, it is also preferable to add a plasticizer. The viscosity of the system can be reduced by the plasticizer, and foam molding can be performed at room temperature. As the plasticizer, known plasticizers such as phthalic acid ester type and phosphoric acid type can be used.
In addition to the above-mentioned components, a foam stabilizer, a flame retardant, etc. can be used.

To produce the foam of the present invention, by mixing the above components, the polyolefin polyol and the organic isocyanate react with each other, and carbon dioxide is generated by the reaction between water and the organic isocyanate to foam. An ordinary foam molding method can be used. In other words, by performing this reaction in the molding die, a foamed molded body that fills the inside of the cavity is formed. It should be noted that this reaction needs to be performed in a liquid state, but when the viscosity of the polyolefin polyol is high, the viscosity may be lowered by heating to cause the reaction, or as described above, the viscosity may be lowered with a plasticizer to cause the reaction. You can also

In the foam of the present invention produced as described above, since the foam cells are finely divided and the ventilation resistance is increased, a high sound absorbing characteristic can be obtained from a relatively low frequency sound to a high frequency sound. Further, since it is hydrophobic due to the polyolefin polyol, the water absorption rate is small. In the present invention, a foam having a water absorption rate of 10% or less is preferable. Further, when compared at the same foam density, tan δ and loss coefficient are large and vibration damping properties are excellent, and also heat resistance is excellent as compared with urethane foam using polyether polyol.

Further, in the foam of the present invention, it is desirable that the above-mentioned mixture is foamed at a foaming ratio of 2 to 30 times. When the expansion ratio is lower than 2 times, almost no sound absorption is obtained, and when the expansion ratio is higher than 30 times, the vibration damping property is rapidly lowered. Further, the urethane foam layer in the present invention can structurally improve the sound absorption coefficient by forming the surface of the urethane foam layer into a textured pattern. This uneven surface having a grainy pattern can be appropriately set according to the frequency region of noise for the purpose of reduction. For example, the depth is 0.2 to 0.5
mm, the distance between the tops of the peaks is 0.5 to 2.0 mm.
It is particularly effective in noise attenuation of 1250H _Z.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a perspective view of a vehicle sound insulation cover according to this embodiment, and FIG. 2 is a sectional view of the vehicle sound insulation cover.

The sound insulation cover of this embodiment prevents leakage of noise generated in the engine room of a truck, and is fixed to the rigid member 1 having a plate-shaped base portion 11 and the base portion 11 of the rigid member 1. The urethane foam layer 2 is formed. The rigid member 1 is formed by bending an iron plate having a thickness of about 1.6 mm to have an inverted L-shaped cross section, and has a base 11 formed in a rectangular shape having a predetermined size and an upper end of the base 11. And a mounting portion 12 extending in a substantially right-angled direction. The mounting portion 12 is formed with a mounting hole 13 for screwing to a vehicle body frame (not shown).

The urethane foam layer 2 is the base 1 of the rigid member 1.
It is composed of urethane foam having a thickness of about 20 mm formed so as to cover one surface of the No. 1. The surface of the urethane foam layer 2 is provided with a grainy pattern in the depth range of 0.2 to 0.5 mm and the distance between the tops of the peaks is 0.5 to 2.0 mm. . The urethane foam layer 2 is formed as follows.

[0024]

[Chemical 2]

That is, 100 parts by weight of a saturated hydrocarbon polyolefin polyol having a side chain (a hydroxyl value of 48 and a number average molecular weight of 2000) represented by the chemical formula 2 and a hydroxyl group of castor oil which is a fatty acid ester are hydrophilic groups. 2.5 parts by weight of a surfactant substituted with sodium sulfate (SO ₄ Na) group, 2.5 parts by weight of water, and a plasticizer (DUP)
20 parts by weight and 20 parts by weight of a flame retardant or the like are mixed by stirring, and an organic isocyanate (Pure / Crud =
80/20, NCO% = 32.2, manufactured by Sumitomo Bayer Urethane Co., Ltd. were mixed so that the NCO index (100 × NCO equivalent / OH equivalent) was 100.

Then, the mixture was immediately poured into a mold for foam molding in which the rigid member 1 was arranged, and foam molding was performed. As a result, the urethane foam layer 2 made of foam is integrally fixed to the surface of the base portion 11 of the rigid member 1.
It should be noted that the foam thus formed is submerged in water at room temperature.
It was 5.1% when the water absorption was examined from the increased weight after immersion for 4 hours. Moreover, when the sound absorption coefficient was measured according to the normal incidence sound absorption measurement method (JIS A1405) using a test piece having a thickness of 30 mm, a sound wave of 500 Hz was 0.57.
1 and the sound wave of 1000 Hz is 0.695, and 2
The 000 Hz sound wave was 0.584 and the 5000 Hz sound wave was 0.652.

The sound insulation cover of this embodiment constructed as described above is arranged as a side wall of the engine room of the truck so that the urethane foam layer 2 faces the engine, and the mounting portion 12 of the rigid member 1 is mounted on the vehicle body frame. It is attached by screwing to the lower surface via the attachment hole 13. And
When the noise generated from the engine room collides with the sound insulating cover, the rigid member 1 shields the noise, and the urethane foam layer 2 absorbs the noise energy to prevent the noise from leaking to the outside. In this case, the urethane foam layer 2 is made of a foam material having an excellent sound absorption rate without being covered with a skin material or the like, and since the surface thereof has a grain-like unevenness, the noise energy is extremely good. Is absorbed by.

Further, since the urethane foam layer 2 is made of a foam having a low water absorption rate, the amount of water absorption is small even if rain water or the like comes into contact therewith, so that excellent sound absorbing performance is maintained. As described above, according to the sound insulation cover of the present embodiment, since the urethane foam layer 2 is made of a foam having a high sound absorption coefficient and a low water absorption coefficient, the skin material covering the urethane foam layer 2 can be omitted. As a result, the sound absorption can be further improved.

Further, since the foam forming the urethane foam layer 2 is also excellent in vibration damping property, in the case where a slight vibration of the vehicle body frame is transmitted to the sound insulation cover and the sound insulation cover produces a radiated sound. Also, it is possible to suppress the surface resonance of the sound insulation cover and contribute to the reduction of noise. Furthermore, the sound insulation cover of the present embodiment can be manufactured at a low cost because the skin material can be eliminated, and the special device is not required.

Further, as in the sound insulation cover of this embodiment, the structure in which one side of the rigid member 1 is attached to the vehicle body and the other side is an open end, the water absorption is high when the urethane foam layer 2 has a high water absorption rate. Therefore, if the weight is increased, the strength of the mounting portion at the time of vibration becomes insufficient, and damage from this portion may be considered. Therefore, when using a foam with a high water absorption rate as in the past, it is necessary to attach a waterproof skin material, partially reinforce the attachment portion, or make the entire rigid member thick. However, in the case of the present embodiment, these needs can be eliminated.

[Embodiment 2] The sound insulation cover of this embodiment has the same basic structure as that of Embodiment 1 described above, but the foam constituting the urethane foam layer is different. That is, the urethane foam layer of this example was formed in the same manner as in Example 1 except that the plasticizer was 40 parts by weight, the surfactant was 3.5 parts by weight, and the water was 3.5 parts by weight. There is. The water absorption of the foam constituting this urethane foam layer was 7.8% as measured by the same method as in Example 1 above. Moreover, when the sound absorption coefficient of this foam was measured by the same method as in Example 1, the sound wave at 500 Hz was 0.315,
The sound wave of 1000Hz is 0.360 and 2000Hz
Sound wave is 0.331, and the sound wave of 5000 Hz is 0.
It was 363.

In the sound insulation cover of the present embodiment having the above-mentioned structure, the skin material covering the urethane foam layer can be eliminated and the sound absorption can be further improved, as in the case of the first embodiment. It has excellent effects such as being able to. [Embodiment 3] The sound insulation cover of the present embodiment has the same basic structure as that of the above-mentioned embodiment 1, but the foam constituting the urethane foam layer is different.

That is, in the urethane foam layer of this example, without using a plasticizer, the surfactant was 3.5 parts by weight, the water was 3.5 parts by weight, and the mixture was heated to 60 ° C. to form a mold. It is formed in the same manner as in Example 1 except that it is injected. The water absorption of the foam constituting this urethane foam layer was 5.3% as measured by the same method as in Example 1 above.
Moreover, when the sound absorption coefficient of this foam was measured by the same method as in Example 1 above, the sound wave of 500 Hz was 0.558, the sound wave of 1000 Hz was 0.665, and 2000
The Hz sound wave was 0.572 and the 5000 Hz sound wave was 0.598.

In the sound insulation cover of the present embodiment having the above-mentioned structure, the skin material covering the urethane foam layer can be eliminated and the sound absorption can be further improved as in the case of the first embodiment. It has excellent effects such as being able to. [Embodiment 4] The sound insulating cover of the present embodiment has the same basic structure as that of the above-mentioned embodiment 1, but the foam constituting the urethane foam layer is different.

That is, the urethane foam layer of this embodiment was prepared by using 100 parts by weight of hydrogenated polybutadiene (hydroxyl value 47, number average molecular weight 2100, manufactured by Nippon Soda Co., Ltd.) in place of the saturated hydrocarbon polyolefin polyol and plasticizing it. It was formed in the same manner as in Example 1 except that 40 parts by weight of the agent, 3.5 parts by weight of the surfactant and 3.5 parts by weight of water were used.
The water absorption of the foam forming this urethane foam layer was 8.1% as measured by the same method as in Example 1 above. Further, when the sound absorption coefficient of this foam was measured by the same method as in Example 1, a sound wave of 500 Hz was 0.340.
And the sound wave at 1000 Hz is 0.382, 20
The 00 Hz sound wave was 0.361 and the 5000 Hz sound wave was 0.379.

In the sound insulation cover of the present embodiment having the above-described structure, the skin material covering the urethane foam layer can be eliminated and the sound absorption can be further improved as in the case of the first embodiment. It has excellent effects such as being able to. [Test] In order to confirm the excellent effect of the sound insulating cover of the present invention, the invention product, the conventional product 1 and the conventional product 2 were produced and a water absorption test was conducted.

The invention product has a thickness of 0.8 mm and a length of 100 m.
A urethane foam layer made of the same foam (single cell, apparent specific gravity 0.10) as in Example 1 having a thickness of about 20 mm, a length of 80 mm, and a width of 330 mm was integrally formed on one surface of an iron plate having a width of m and a width of 350 mm. It was done. Conventional product 1
Is a polyether polyol (having a hydroxyl value of 28 and a number average molecular weight of 600 when replacing the saturated hydrocarbon polyolefin polyol in forming the foamed urethane foam layer).
0, 100 parts by weight of "Sumiphen 3063" manufactured by Sumitomo Bayer Urethane Co., Ltd., and 0.5 parts by weight of a silicone oil type foam stabilizer ("SZ-1313" manufactured by Nippon Unicar Co., Ltd.) as a surfactant. Using 2.0 parts by weight of water,
It was produced in the same manner as the invention product except that no plasticizer was used. In addition, this foam is an open cell,
The apparent specific gravity is 0.11.

Conventional product 2 is obtained by coating the surface of the urethane foam layer of conventional product 1 with a 40 μm thick polyurethane film. These invention products, the conventional products 1 and the conventional products 2 were immersed in a water tank having a depth of 100 mm at room temperature, and the respective weight changes after 10 minutes, 20 minutes and 30 minutes were measured. The results are shown in Table 1.

[0039]

[Table 1] As is clear from Table 1, in the case of the conventional product 1, the weight increase rate of the foam after 10 minutes was 20.7%, and the weight increase rate of the foam after 20 minutes and 30 minutes was 24. It was 1%. From this, it is understood that when the urethane foam layer comes into contact with water, it absorbs water rapidly and has a high water absorption rate. Therefore,
It is inappropriate to use the conventional product 1 in a portion that is in contact with rainwater or the like.

Further, in the case of the conventional product 2, since it has the skin material covering the surface of the urethane foam layer, it is understood that the urethane foam layer does not absorb water at all. On the other hand, in the case of the invention product, the rate of increase in the weight of the foam after 10 minutes was only 0.2%.
It was only 0.4% after 30 minutes and after 30 minutes.
From this, it can be seen that the urethane foam layer of the invention product hardly absorbs water even if it comes into contact with water. Therefore, the invention product does not require a skin material or the like, and can be suitably used for a portion that comes into contact with rainwater or the like.

[0041]

According to the sound-insulating cover of the first aspect of the invention, the urethane foam layer reacts with a mixture of a polyolefin polyol having a saturated hydrocarbon resin skeleton, water as a foaming agent, and an organic polyisocyanate. Since it is made of a foam having a low water absorption rate, it is possible to further improve the sound absorbing property by eliminating the skin material.

Further, the sound insulation cover of the present invention can be manufactured at a low cost because the skin material can be omitted, the manufacture is simplified, and no special device is required. According to the invention of claim 2, the foam is formed by reacting the mixture in the presence of a surfactant having a fatty acid ester having a hydrophilic group in the chain as a basic skeleton. Water can be uniformly dispersed in the polyolefin polyol, and the water absorption of the foam can be greatly reduced.

According to the third aspect of the invention, since the surface of the urethane foam layer is the uneven surface having a grain pattern, the sound absorption coefficient of the urethane foam layer can be improved. When the rigid member has a mounting portion on at least one side and the other side has an open end as in the invention described in claim 4, the urethane foam layer is a foam body having a small water absorption rate. By being formed, it is possible to eliminate the need for a waterproof skin material and the need for measures to strengthen the rigid member.

[Brief description of drawings]

FIG. 1 is a perspective view of a vehicle sound insulation cover according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a vehicle sound insulation cover according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a mounting state of a conventional sound insulation cover for a vehicle.

[Explanation of symbols]

1, 5 ... Rigid member 11 ... Base portion 12 ... Mounting portion
13 ... Mounting holes 2, 6 ... Urethane foam layer 4 ... Body frame 7 ...
Skin material

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Koyamauchi 3600 Amigazu, Kita Sotoyama, Komaki City, Aichi Prefecture, Tokai Rubber Industry Co., Ltd. (72) Inventor Kiyomi Nishida, Komaki City, Aichi Prefecture 1 Tokai Kasei Kogyo Co., Ltd. at No. 4203 (72) Inventor Hiroshi Ando In 1 Tokai Kasei Kogyo Co., Ltd. at No. 4203, Shimokowa, Komagaki City, Aichi Prefecture (56) Reference JP-A-8-150884 (JP, A) JP-A-8-40154 (JP, A) JP-A-10-87776 (JP, A) JP-A-10-81142 (JP, A) JP 59-7840 (JP, U) JP Kai 62-194027 (JP, U) Actual Kai 58-194966 (JP, U) Actual Kaihei 2-105051 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1 / 00-35/00 B60R 13/08

Claims (4)

(57) [Claims] 1. A sound insulation cover for vehicles, comprising a plate-shaped rigid member and a urethane foam layer fixed to the rigid member, wherein the urethane foam layer comprises a polyolefin polyol having a saturated hydrocarbon resin skeleton, A sound insulation cover for a vehicle, which is formed of a foam made by reacting a mixture of water as a foaming agent and an organic polyisocyanate, and has a water absorption rate of 10% or less. 2. The foam is formed by reacting the mixture in the presence of a surfactant having a basic skeleton of a fatty acid ester having a hydrophilic group in the chain. Sound insulation cover for vehicle as described. 3. The vehicle sound insulation cover according to claim 1 or 2, wherein the surface of the urethane foam layer is an uneven surface having a grain pattern. 4. The sound insulation cover for a vehicle according to claim 1, wherein the rigid member has a mounting portion on at least one side and the other side has an open end.