JP3525654B2 - High rigidity sound absorbing material and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-rigidity sound absorbing material and a manufacturing method thereof, and more particularly to a high-rigidity sound absorbing material used in an engine room for the purpose of absorbing and insulating engine sound and a manufacturing method thereof. .

[0002]

2. Description of the Related Art Conventionally, various sound and vibration parts have been used in an engine room in order to reduce noise generated by an engine. For example, a hood insulator installed on the back of the hood, a resonator for reducing intake noise, or an in-engine insulator installed on a wall surface.

Among these sound and vibration parts, the engine proximity shield cover is one of the parts closest to the engine, and only a material having sufficient heat resistance is applied. Conventionally, in order to meet this requirement, As the material composition, only resin plates were used, and most of the parts provided with sound absorbing materials were made of glass wool, so that sound absorption and sound insulation frequency newing were impossible.

The conventional engine cover is made of a thin steel plate in order to improve the sound insulation performance in terms of structure, and a specific example thereof is a type having a Helmholtz resonator in a part of the plate (Actual exploitation No. 57-25144). Japanese Patent Laid-Open No. 54-
No. 47020), a type having a weather strip at the grounding portion to prevent water leakage on the engine (Actual No. 57-25).
No. 143), a type that is directly installed in a portion where sound is generated (Japanese Utility Model Publication No. 63-40232, Japanese Utility Model Publication No. 64-5).
1738), a Helmholtz type (Japanese Patent Laid-Open No. 7-13573, Japanese Patent Laid-Open No. 7-64564), which has both air permeability and sound insulation performance, have been proposed.

However, in these types, the effect is mainly applied only to a specific frequency, and it is difficult to exert the effect in the entire frequency range.

Further, a general sound absorbing material is used to improve the sound insulation performance and the sound absorbing performance (Japanese Patent Laid-Open No. 53-900).
No. 01, No. 56-176388, and No. 62-70922), these have some effect over the whole area in contrast to the above structure type, but especially in the low frequency range. It is difficult to have an effect.

[0007]

The engine noise of a vehicle, in particular, changes basically in accordance with the engine speed, but basically, noise in a low frequency region of 500 Hz or less is a problem. It has been a problem to obtain a sound absorbing structure that is particularly effective over the entire frequency range. At the same time, since the space inside the vehicle engine room is limited, achieving a high-performance and compact structure was also a serious issue. Further, since the engine room has a relatively high temperature atmosphere, the sound absorbing material is also required to have some heat resistance.

Therefore, an object of the present invention is to have excellent sound absorbing performance in a low frequency region of 500 Hz or less, and
An object of the present invention is to provide a compact sound absorbing structure that has sufficient sound absorbing performance even in a high frequency range and further does not take up space.

[0009]

The above objects of the present invention are as follows.
A sound absorbing material made of a woven fabric or a non-woven fabric made of a fiber aggregate composed of short fibers and / or long fibers, wherein the fibers constituting the sound absorbing material are made of polyester having a diameter of 10 to 40 μm. 70-100% by weight
Is a binder fiber having a double core portion and a surface portion in the cross-sectional direction, and the core portion has a high softening point and the surface portion has a low softening point, and the difference between the softening points is 20 to 150 ° C. It is a fiber in the range, and the average thickness of the sound absorbing material is 3 to 3 as a whole.
It was achieved by a high-rigidity sound absorbing material having a surface density of 0 mm and an area density of 200 to 2,000 g / m ² and a method for producing the same.

The present invention will be described in more detail below. The high-rigidity sound absorbing material of the present invention needs to be made of a fiber assembly composed of short fibers having a fiber length of 100 mm or less and / or long fibers having a fiber length of 100 mm or more.
Sound absorption is the conversion of sound energy into heat energy and the like, so it is necessary to improve the energy conversion efficiency in order to improve this performance. This efficiency can be improved by increasing friction with air, and increasing the surface area of the sound absorbing material is effective for achieving this purpose. From this point, among various sound absorbing materials, a fiber assembly having a large surface area per unit weight is suitable. Further, since the sound absorbing performance does not depend on the length of the constituent fibers, there is almost no need to specify the fiber length to secure the sound absorbing performance.

Further, depending on the purpose of using the sound absorbing material, it may be better to use short fibers or long fibers. For example, since short fibers themselves are short, when molded into a sound-absorbing material, the sound-absorbing material has good mold followability and high shape retention. Moreover, since long fibers have high mechanical strength, they are good when it is desired to obtain rigidity in the sound absorbing material, but not particularly limited thereto.

However, when the sound absorbing material is manufactured or the rigidity of the sound absorbing material itself is taken into consideration, the mechanical strength of the sound absorbing material is influenced by the fiber length, so that it has the meaning of defining the fiber length. When the fiber is molded into a sound absorbing material, the fiber length is 30
It is preferably in the range of -100 mm. Fiber length is 3
If it is less than 0 mm, the fiber length is too short, and it is difficult to mold it into a sound absorbing material. On the other hand, it is difficult to uniformly disperse fibers having a length of more than 100 mm and mold them in a general fiber sound absorbing material manufacturing apparatus. Therefore,
There is a high possibility that some of the fibrous bodies will become uneven sound absorbing materials in the sound absorbing material, and it will be difficult to always ensure a certain performance.

The fiber assembly constituting the sound absorbing material may be in the form of woven fabric or non-woven fabric. This is because the sound absorbing performance does not depend on the form of this fiber assembly. However, in order to secure the bulkiness and the mechanical strength of the sound absorbing material, the shape of the fiber assembly strongly depends, so it is necessary to determine the shape of the sound absorbing material in consideration of the environment around which the sound absorbing material is installed. is there. At this time, the non-woven fabric form is preferable when the bulkiness is important, and the woven fabric form is preferable when the mechanical strength is important.

The fiber constituting the sound absorbing material has a diameter of 10
It is necessary to be in the range of -40 μm. The sound absorbing performance of the sound absorbing material depends on the average fiber diameter of the fiber assembly that constitutes the sound absorbing material, and the smaller the fiber diameter, the higher the sound absorbing performance. However, fibers having a diameter of less than 10 μm are not common, and the rigidity of the fibers themselves is small, so that it is difficult to use them as parts, and when the rigidity of the fibers is small, it is one of the performances of the sound absorbing material that is bulky. It is difficult to give
Furthermore, the binding force of the fiber itself also becomes small. on the other hand,
If fibers having a diameter of more than 40 μm are used, the sound absorbing performance is deteriorated.

Further, the fibers constituting the sound absorbing material must be made of polyester. This is because polyester has many polymers having a relatively high melting point and is suitable as a material for a sound absorbing material used in a relatively high temperature atmosphere such as in an engine room of an automobile. In particular, polyethylene terephthalate, which is a general polyester, has a melting point of about 250 ° C. and is suitable, but not particularly limited. Further, polyester has high recyclability, and it is possible to manufacture the nonwoven fabric again by re-opening the end material after being cut out as a sound absorbing material. Furthermore, it is also possible to melt polyester fibers such as scraps and re-spin the fibers.

The fibers constituting the sound absorbing material are 70 to 10 thereof.
It is necessary that 0% by weight is a binder fiber having a double core portion and a surface portion in the cross-sectional direction, and the core portion has a high softening point and a surface portion has a low softening point. . Binder fibers are used for imparting moldability to non-woven fabrics, but since the low softening point parts of the fiber surface are fused together during heat molding, it is possible to mold according to the mold. There is.

When the sound absorbing material is used in the intake system in the engine room, a skin such as a spun bond is attached to the surface of the sound absorbing material so that the fibers of the sound absorbing material are not removed by the intake air. The sound absorbing material was protected. When the binder fiber is used in the skin in the range of 70 to 100% by weight, the above-mentioned problem does not occur because the surface fiber is bonded by the binder fiber. Therefore, it is not necessary to install a skin to prevent the sound absorbing material from scattering.

At this time, if the content of the binder fibers is less than 70% by weight, there is no problem in molding, but there is a risk that some of the surface fibers will be scattered by the intake air. The fibers constituting the sound absorbing material may be 100% by weight of the binder fiber, have a very high rigidity, and become a high quality sound absorbing material in which the fibers do not scatter.

The melting point of the low softening point portion of the surface portion of the binder fiber must be low in the range of 20 to 150 ° C. with respect to the core portion. This is because it is necessary for imparting moldability to the sound absorbing material. Therefore, depending on the difference in the softening point, in the temperature range in which only some of the fibers are softened,
By using the softened fiber as a binder, moldability can be imparted to the fiber assembly. When the difference in softening point is less than 20 ° C., it becomes difficult to control the temperature at the time of heat molding, which is not practical. vice versa,
When the difference in softening point exceeds 150 ° C., the temperature of the softening point is extremely lowered, and it may be difficult to secure the shape of the sound absorbing material used at room temperature or high temperature.

This is because the polyester fibers other than the binder fibers are considered to have a melting point similar to that of the core material of the binder fibers, so that the larger the temperature difference of the softening points of the binder fibers, the easier the molding. However, when the surface part melts in a high temperature atmosphere, the shape of the molded sound absorbing material returns to the original sheet shape of the sound absorbing material, which is a problem.

For example, a sound absorbing material used for an engine cover is required to have high heat resistance in order to withstand radiant heat of an engine. Therefore, in the case of a binder fiber using polyethylene terephthalate, which is the most common polyester, as the core material, the melting point of the core material is about 250 ° C.,
It is necessary that the softening point of the surface portion be in the range of 110 to 230 ° C. From the viewpoint of heat resistance and moldability, the temperature of the softening point of the surface portion is more preferably in the range of 170 to 200 ° C., but is not particularly limited.

The thickness of the sound absorbing material needs to be in the range of 3 to 30 mm. If the thickness is less than 3 mm, the sound absorbing performance cannot be ensured. On the contrary, if the thickness is more than 30 mm, the sound absorbing material is too thick and a space for installation is required, so that the layout cannot be established in many cases. , The applications are narrowed.

The surface density of the sound absorbing material is 200 to 2,000 g /
It is effective that it is within the range of m ² . Area density is 200
If it is less than g / m ² , the rigidity as a sound absorbing material cannot be secured. On the other hand, if it exceeds 2,000 g / m ² , the performance is not improved because the weight and the cost associated therewith are exceeded, and it is not effective. In addition, as the surface density increases, the air permeation amount of the sound absorbing material itself increases. Is reduced, so that sound may be reflected.

The structure in which the above-mentioned sound absorbing material is installed on one or both sides of the core material of any material, while maintaining the sound absorbing performance,
Furthermore, since it is possible to increase the rigidity of the sound absorbing material,
Suitable for the purposes of the invention.

The substance constituting the core material is a resin plate, a metal plate,
A plate-like member having a certain degree of rigidity, such as a fiber aggregate or a resin-impregnated fiber aggregate, may be used, but is not particularly limited.

The fiber assembly constituting the core material may be a natural fiber or a synthetic fiber, but the thickness of the fiber, the unit length of the fiber, the distribution of the fiber body, etc. can all be regulated, and they are always the same. It is preferable to use a synthetic fiber that can produce a uniform density distribution.

As the synthetic fibers constituting the fiber assembly,
It can be appropriately selected from known synthetic fibers and used, and examples thereof include nylon, polyacrylonitrile, polyacetate, polyethylene, linear polyester, polyamide and the like. Among these synthetic fibers, it is preferable to use polyester fibers which can be blended with fibers having different softening points in view of advantages such as recycling of the sound absorbing material, simultaneous integral moldability, and ability to maintain the shape.

Further, it is also effective that the fiber body is formed into a fiber aggregate by using a method such as needle punching, since the rigidity of the fiber body can be improved.

In the case of a laminated sound absorbing material having a core material, the thickness ratio of the sound absorbing material layer is preferably in the range of 3 to 40% of the total thickness of each surface. Therefore, when installing the sound absorbing material on only one side, install the sound absorbing material with a thickness in the range of 3 to 40% of the total thickness, and when installing the sound absorbing material on both sides, each surface has the total thickness. It is preferable to install the sound absorbing material with a thickness in the range of 3 to 40%. If the installed thickness of the sound absorbing material is less than 3%, the sound absorbing performance cannot be secured, which is not suitable. On the other hand, when the thickness exceeds 40%, there is no problem in sound absorbing performance, but since there is almost no difference from the case where there is no core material as a whole, there is no point in installing the core material.

In the present invention, a part of the plate-shaped sound absorbing material is used.
At least 1 or more 4-100 cm ²Opening in the range
Part or missing part, where sound absorbing material is installed and sound absorption
The volume 1 formed between the material and the thickness of the sound absorbing material
Depending on the ratio with the volume 2 formed by the opening and the like
The resonance of its constituent system in the range of 50 to 450 Hz.
Preferably, it can be formed.

This is first established by constructing the Helmholtz resonator section with a sound absorbing material. The Helmholtz resonator will be described below.

The Helmholtz resonator is a structure that absorbs sound at a target frequency by newly forming resonance, and is composed of the volume of the neck and the volume of the volume as shown in FIG. The set frequency fr for the purpose of absorbing sound is calculated by the following formula: Formula 1 according to the ratio between the volume of the neck and the volume of the volume.
Can be set like.

[0033]

[Equation 1] c: speed of sound S: cross-sectional area of neck L: length of neck V: volume of volume

Here, the volume of the neck means a hole formed in the sound absorbing material by an opening formed in a part of the plate-like sound absorbing material or a missing portion of the sound absorbing material (see FIG. 2). The volume formed by the thickness of the sound absorbing material. Further, the volume part means a space formed on the back surface of the portion where the sound absorbing material is installed.

At this time, since a new resonance is formed at the set frequency, the antinode of the sound pressure, which has existed there conventionally, is crushed by the formed resonance, and as a result, the silencing at the target frequency can be achieved.

In order to most effectively use the Helmholtz resonator constituted by the sound absorbing material, it is preferable to install the resonator when the resonance of the sound pressure of the set frequency occurs, and the sound pressure is also attenuated. growing. However, in practice, it is often difficult to install a resonator at a place where a desired resonance is generated, and a resonator having large attenuation may not be obtained. In this case, by utilizing the property that the rebound does not increase unless the newly formed resonance increases, intentionally removing the resonator from the mode and installing it has an effect on the entire frequency range. It is effective as a sound absorbing structure.

It is also possible to install a weak Helmholtz resonator having a small volume in order to form a weak resonance. Since the setting of the frequency of the Helmholtz resonator is determined by the ratio of the neck portion and the volume portion from Equation 1, theoretically it does not depend on the volume capacity. However, since the damping effect depends on the volume, a larger volume is more effective for silencing the same set frequency.

In order to absorb a plurality of frequencies,
It is effective to install a plurality of Helmholtz resonators set to at least two frequencies or a plurality of Helmholtz resonators set to at least two or more same frequencies, and a sound absorbing effect can be obtained. At this time, whether or not the volume is the actual level is determined in consideration of the total volume, but there is no particular limitation.

The cross-sectional area of the opening or missing portion of the sound absorbing material is 4
It is preferably in the range of -100 cm ² . The frequency of the Helmholtz resonator is set by the volume of the neck and the volume of the volume. Therefore, when tuning the set frequency with the sound absorbing material, the volume of the neck portion is determined by the area of the opening or missing portion on the surface of the sound absorbing material and the thickness of the sound absorbing material, and the sound absorbing material is installed. The space formed on the back surface of the sound absorbing material becomes a volume part. Therefore, when it is desired to operate the set frequency, this area and the thickness of the sound absorbing material may be changed.

At this time, if the cross-sectional area of the neck portion is less than 4 cm ² , the frequency can be set, but the minimum necessary damping effect cannot be obtained, which is meaningless as the sound absorbing duct structure. On the contrary, a Helmholtz type resonator having a cross-sectional area exceeding 100 cm ² has a very large capacity, and there is almost no situation in which a resonator having such a large size is used.
It is unsuitable because it is out of the practical level. When used as a small passenger car, it is particularly preferable that the cross-sectional area of the neck is in the range of 5 to 25 cm ^{2 in view} of the balance between volume and performance.

The opening or the like may be a single hole type having one hole or a slit type having a plurality of holes. These can be selected depending on the volume of the Helmholtz resonator and the set frequency, but are not particularly limited. Further, a Helmholtz resonator having a neck portion of a type in which the neck portion is inserted in the volume portion is particularly effective in order to set the frequency on the low frequency side under a smaller volume while securing the cross-sectional area. Further, the sound absorbing material can be installed at any place such as an opening.

By adjusting the volume of the neck portion and the tuning of the volume portion, it is possible to set the frequency to a certain degree from the equation (1). However, since the sound absorbing material does not completely stop ventilation and its rigidity is lower than that of a plate made of general resin or the like, the frequency setting cannot be completely determined by the formula (1). Therefore, the formula 1 is merely a guideline for setting the frequency within a certain range. On the contrary, this wide frequency setting is often convenient when used as a sound absorbing material, and further, this setting reduces bounce.

In the present invention, the sound absorbing material is 50 to 4
It is preferable to set in the range of 50 Hz. 50 Hz
At frequencies below 1, the size of the volume formed behind becomes extremely large when the opening or the like is made to have an actual size, and the size is not a realistic size. Conversely, 450Hz
At frequencies above, the sound absorbing material alone already has sufficient sound absorbing performance, so setting the resonator becomes meaningless.

Naturally, the sound absorbing material has a sufficient sound absorbing effect in the medium frequency and high frequency regions exceeding 450 Hz. Therefore, the above-mentioned frequency setting is a limited item necessary when sound absorbing performance is given in a region other than the medium frequency region and the high frequency region.

The high-rigidity sound absorbing material of the present invention is preferably used for parts in the engine room of a vehicle in order to reduce the sound pressure in the engine room. Conventional sound absorbing materials have almost no rigidity, so when seeking rigidity for sound absorbing materials,
The epidermis with high rigidity was attached. Since the sound absorbing material alone has high rigidity, the present invention has an advantage that it can be used without a skin material in a part of a portion where rigidity is required. Further, since the sound pressure distribution is wide in the engine room and there are many parts with high sound pressure, it is most suitable to apply the high-rigidity sound absorbing material of the present invention to the engine room.

Further, in order to completely prevent the fibers from falling out of the sound absorbing material or to protect the sound absorbing material, the side surface of the sound absorbing material on the engine side or the sound absorbing material is covered, and the average fiber length is 1 to 1.
00 cm, average diameter 1 to 30 μm, areal density 20 to 200 g
It is effective to install a non-woven fabric skin made of synthetic fibers in the range of / m ² , but not particularly limited thereto.

The fibers to be constituted may be short fibers having a length of 10 cm or less, or long fibers having a length longer than that. These fibers are formed into a cloth-like non-woven fabric or a woven fabric. In the case of a non-woven fabric, the needle punch manufacturing method or the manufacturing method in which a part of the cloth is heat-sealed to increase the rigidity of the cloth, It is effective because it can also secure the property. In addition, it is particularly effective to use only long fibers having a length of 10 cm or more as the constituent fibers because the rigidity of the fabric can be further improved. Further, it is possible to apply water repellency or oil repellency treatment to this skin material, which is very effective for protecting the sound absorbing material in the vicinity of the engine, but is not particularly limited.

The high-rigidity sound absorbing material of the present invention is preferably used by being installed in a part of the intake duct in order to reduce the intake sound of the vehicle. Conventionally, a resonator is installed in the intake system as a means of reducing the intake sound of the engine, but by replacing this resonator with this sound absorbing material,
It is possible to expand the effective space in the engine room, and it is possible to obtain a sufficient intake noise reduction effect even in the high frequency range other than the set frequency.

The high-rigidity sound-absorbing material of the present invention can be produced by opening polyester fibers, mixing them, and making them into a bulky shape by a card-type nonwoven fabric process or an air-laid nonwoven fabric process, and then a far-infrared oven or a hot-air oven. A non-woven sound absorbing material is processed in a needle-punching process using the above, and after pre-softening the sound absorbing material in a temperature range of 150 to 250 ° C., a sound absorbing material layer is press-formed into a required shape in a cold press mold. Is used.

In order to uniformly mix the fibers constituting the sound absorbing material, the polyester fibers are put into a fiber opening machine, and the fibers are opened until the fibers are uniformly dispersed. If polyester fibers that are not uniformly dispersed are used here, there is a possibility that when the sound absorbing material is molded, it becomes a non-uniform sound absorbing material with partially different rigidity.

The uniformly dispersed fibers are further made into a bulky nonwoven fabric by a card layer type nonwoven fabric manufacturing apparatus or an air laid type nonwoven fabric manufacturing apparatus. The card layer type is
It is often used because it has the advantage that the constituent fibers are particularly uniform. In addition, since the line speed is high in the air-laid system, it is preferable to carry out the manufacturing when the manufacturing time is particularly important.

After being made into a bulky nonwoven fabric, in order to adjust the thickness and areal density to a desired value, it is preheated by using a far infrared oven or a hot air oven, and then a sound absorbing material is put into two rolls having a specified thickness. To define the thickness. In order to increase the surface rigidity of the surface of the sound absorbing material, if you want to make the sound absorbing material so thin that it cannot be compressed in the roll processing process, perform a needle punching step at the end to obtain an appropriate needle density, sound absorbing material feed speed, needle Stipulates the stroke length through which the sound absorbing material penetrates to obtain the desired sound absorbing material.

When the high-rigidity sound absorbing material thus obtained is actually used, it is pre-softened in a temperature range of 150 to 250 ° C. by a hot air circulation oven or a far infrared oven, and then used in a shape to be used thereafter. Cold press with mold. The high-rigidity sound absorbing material of the present invention can be molded into an arbitrary shape by blending binder fibers, and the molding is performed according to the intended use.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of installing the high-rigidity sound absorbing material of the present invention in the vicinity of a vehicle engine, it was confirmed that the sound absorbing material has a high sound deadening characteristic not only in a low frequency region but also in a middle frequency region and a high frequency region. We were able to.

[0055]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.

Example 1 A nonwoven fabric was formed of polyester short fibers having an average diameter of 15 μm, and 80% by weight of the nonwoven fabric was mixed with binder fibers. The softening point of the binder fibers was the melting point of general polyester (polyethylene terephthalate). (About 25
0 ° C.) to about 40 ° C. lower. Thickness of this sound absorbing material is 1
A high-rigidity sound absorbing material 1 was manufactured by molding to 0 mm and an areal density of 1000 g / m ² . At this time, the polyester fibers having the above-mentioned composition were uniformly mixed by an opening machine, and a bulky nonwoven fabric was manufactured by a card type nonwoven fabric process. This bulky nonwoven fabric was inserted into a hot air oven and processed to a thickness of 10 mm with a rotary roll. The obtained nonwoven fabric sound absorbing material was placed in a hot air oven at 250 ° C. for 3 minutes, and immediately thereafter, cold-pressed into a mold in the shape of a jig for experiment to obtain a high-rigidity sound absorbing material 1 having a thickness of 10 mm.

Example 2 A high-rigidity sound absorbing material 2 was manufactured in exactly the same manner as in Example 1 except that the binder fiber content was 70% by weight. At this time, the polyester fibers having the above-mentioned composition were uniformly mixed by an opening machine, and a bulky nonwoven fabric was manufactured by an air-laid nonwoven fabric process. This bulky nonwoven fabric was processed into a thickness of 10 mm by a needle punching process. The obtained non-woven sound absorbing material is 2
It was placed in a hot air oven at 50 ° C. for 3 minutes, and immediately thereafter, cold-pressed into a mold in the shape of an experimental jig to obtain a high-rigidity sound absorbing material 2 having a thickness of 10 mm.

Example 3 A high-rigidity sound absorbing material 3 was manufactured in exactly the same manner as in Example 1 except that the blending amount of the binder fiber was 100% by weight. At this time, the polyester fibers having the above-mentioned composition were uniformly mixed by an opening machine, and a bulky nonwoven fabric was manufactured by an air-laid nonwoven fabric process. This bulky nonwoven fabric was inserted into a far-infrared oven and processed into a thickness of 10 mm with a rotary roll. The obtained non-woven sound absorbing material was placed in a hot air oven at 250 ° C. for 3 minutes, and immediately thereafter, cold pressed into a mold having the shape of an experimental jig to obtain a high-rigidity sound absorbing material 3 having a thickness of 10 mm.

Example 4 A high-rigidity sound absorbing material 4 was manufactured in exactly the same manner as in Example 1 except that the average diameter of the polyester fiber was 10 μm. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 4.

Example 5 A high-rigidity sound absorbing material 5 was manufactured in exactly the same manner as in Example 1 except that the average diameter of the polyester fiber was 40 μm. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 5.

Example 6 A high-rigidity sound absorbing material 6 was manufactured in exactly the same manner as in Example 1 except that the difference in softening point of the binder fiber was set to about 20 ° C. The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 6.

Example 7 A high-rigidity sound absorbing material 7 was manufactured in exactly the same manner as in Example 1 except that the difference in softening point of the binder fiber was set to about 80 ° C. The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 7.

Example 8 Except that the difference in softening point of the binder fiber was set to about 150 ° C.,
A highly rigid sound absorbing material 8 was manufactured in exactly the same manner as in Example 1.
The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 8.

Example 9 A high-rigidity sound absorbing material 9 was manufactured in exactly the same manner as in Example 1.
The manufacturing method at this time was also carried out in exactly the same manner as in Example 1, and the high-rigidity sound absorbing material 9 was obtained by forming the thickness to 3 mm by cold pressing.

Example 10 A high-rigidity sound absorbing material 10 was manufactured in exactly the same manner as in Example 1. The manufacturing method at this time was performed in exactly the same manner as in Example 1, and the high-rigidity sound absorbing material 10 was obtained by molding to a thickness of 30 mm by cold pressing.

Example 11 Example 1 was repeated except that the surface density of the sound absorbing material was set to 200 g / m ^2.
A highly rigid sound absorbing material 11 was manufactured in exactly the same manner as in. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 11.

Example 12 A high-rigidity sound absorbing material 12 was manufactured in exactly the same manner as in Example 1 except that the surface density of the sound absorbing material was 1500 g / m ² . The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 12.

Example 13 A high-rigidity sound absorbing material 13 was manufactured in exactly the same manner as in Example 1 except that the surface density of the sound absorbing material was 2000 g / m ² . The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 13.

Example 14 A high-rigidity sound absorbing material 14 was manufactured in exactly the same manner as in Example 1 except that the sound absorbing material was made of woven cloth. The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a high-rigidity sound absorbing material 14.

Example 15 A highly rigid sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was installed on one surface of the wooden board, and the high-rigidity sound absorbing material 15 was obtained by making the thickness of the high-rigidity sound absorbing material 30% of the total thickness.

Example 16 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was installed on one side of a polypropylene plate, and the thickness of the high-rigidity sound absorbing material was set to 30% of the total thickness to obtain a high-rigidity sound absorbing material 16.

Example 17 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was installed on one surface of a polyester plate, and the high-rigidity sound absorbing material 17 was obtained by making the thickness of the high-rigidity sound absorbing material 30% of the total thickness.

Example 18 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound-absorbing material was installed on both sides of the polyester plate, and the thickness of the high-rigidity sound-absorbing material on one side was 30% of the total thickness to obtain a high-rigidity sound-absorbing material 18.

Example 19 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was installed on one surface of a polyester plate, and the thickness of the high-rigidity sound absorbing material on one surface was 3% with respect to the total thickness to obtain a high-rigidity sound absorbing material 19.

Example 20 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material is processed into shape 1 (see FIG. 3),
The area of the opening was set to 9 cm ^2, and the volume of the body stack behind was adjusted to obtain a high-rigidity sound absorbing material 20 having a resonator whose frequency was set to 300 Hz.

Example 21 A high-rigidity sound absorbing material 21 was obtained in exactly the same manner as in Example 20 except that the high-rigidity sound absorbing material was processed into the shape 2 (see FIG. 4).

Example 22 A high-rigidity sound absorbing material 22 was obtained in the same manner as in Example 20 except that the high-rigidity sound absorbing material was processed into the shape 3 (see FIG. 5).

Example 23 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 16.
This high-rigidity sound absorbing material is processed into a shape 1 so that the area of the opening becomes 9 cm ^2, and the volume of the body stack behind is adjusted to have a resonator with a frequency set to 300 Hz. I got 23.

Example 24 A high-rigidity sound absorbing material 24 was obtained in exactly the same manner as in Example 20 except that the area of the opening was set to 4 cm ² and the set frequency of the resonator was set to 100 Hz.

Example 25 A high-rigidity sound absorbing material 25 was obtained in the same manner as in Example 20 except that the area of the opening was 100 cm ² and the set frequency of the resonator was 400 Hz.

Comparative Example 1 A sound absorbing material was produced in exactly the same manner as in Example 1, except that the binder fiber content was 60% by weight. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a sound absorbing material.
When this sound absorbing material was installed in an experimental device and an experiment was conducted, fibers were scattered during the experiment and accurate data could not be captured.

Comparative Example 2 A sound absorbing material was produced in exactly the same manner as in Example 1 except that the average diameter of the polyester fiber was 50 μm. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a sound absorbing material.

Comparative Example 3 A sound absorbing material was manufactured in exactly the same manner as in Example 1. The manufacturing method at this time was performed in exactly the same manner as in Example 1, and a sound absorbing material was obtained by forming the thickness to 2 mm by cold pressing.

Comparative Example 4 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. The manufacturing method at this time was performed in exactly the same manner as in Example 1, and a high-rigidity sound absorbing material was obtained by forming the thickness to 35 mm by cold pressing. I tried to set up this sound absorbing material in the experimental equipment, but the sound absorbing material was too thick to stop the ventilation, so I could not do the experiment.

Comparative Example 5 Example 1 was repeated except that the surface density of the sound absorbing material was 100 g / m ^2.
A sound absorbing material was manufactured in exactly the same manner as. The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a sound absorbing material.

Comparative Example 6 A sound absorbing material was manufactured in exactly the same manner as in Example 1 except that the surface density of the sound absorbing material was 2500 g / m ² . The manufacturing method at this time was performed in exactly the same manner as in Example 1 to obtain a sound absorbing material.

Comparative Example 7 A sound absorbing material was manufactured in exactly the same manner as in Example 1 except that the difference in softening point of the binder fiber was set to about 15 ° C. The manufacturing method at this time was performed in exactly the same manner as in Example 1, but the difference in the softening point was small, and the whole melted, and the sound absorbing material could not be obtained.

Comparative Example 8 A sound absorbing material was produced in exactly the same manner as in Example 1 except that the difference in softening point of the binder fiber was set to 160 ° C. The manufacturing method at this time was performed in the same manner as in Example 1 to obtain a sound absorbing material.
Although this sound absorbing material was installed in the experimental device and the experiment was conducted, the shape of the acoustic absorbing material could not be maintained due to heat transfer of the experimental device during the experiment, and accurate data could not be obtained.

Comparative Example 9 A highly rigid sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was placed on one surface of a wooden board, and the thickness of the high-rigidity sound absorbing material on one surface was 2% with respect to the total thickness to obtain a sound absorbing material.

Comparative Example 10 A high-rigidity sound absorbing material was manufactured in exactly the same manner as in Example 1. This high-rigidity sound absorbing material was installed on one side of a wooden board, and the sound absorbing material was obtained by making the thickness of the high-rigidity sound absorbing material on one surface 42% of the total thickness. Is no longer sufficient, and the feeling of rigidity is reduced, and it is meaningless to provide a core material.

Comparative Example 11 A sound absorbing material was obtained in exactly the same manner as in Example 20 except that the area of the opening was set to 3 cm ² , but sound was absorbed at that frequency despite setting the resonator. The effect was not obtained, and the performance was the same as that of a general sound absorbing material.

Comparative Example 12 A sound absorbing material was obtained in exactly the same manner as in Example 20 except that the area of the opening was set to 110 cm ^2, and a resonator was used at a frequency of 50 to 450 Hz with the area of this opening. When setting, the volume part becomes large capacity, lacking in practicality,
Furthermore, it was difficult to install in the experimental device, and it was not possible to capture the sound absorption data.

Comparative Example 13 Example 20 was repeated except that the set frequency of the resonator was set to 40 Hz.
A sound absorbing material was obtained in exactly the same manner as the above, but when the resonator was set to a frequency of 50 to 450 Hz in the area of this opening, the volume became large, which was impractical, and further in the experimental apparatus. Since it was difficult to install the sound absorption data, it was not possible to capture the sound absorption data.

Comparative Example 14 Example 2 was repeated except that the set frequency of the resonator was set to 500 Hz.
Although a sound absorbing material was obtained in exactly the same manner as 0, the sound absorbing performance at frequencies around 500 Hz before and after the installation of the 500 Hz resonator was hardly changed, and there was no merit to install the resonator.

Conventional Example 1 A molding felt having an areal density of 1.0 kg / m ² and a thickness of 10 mm composed of opened natural fibers and synthetic fibers was used as a sound absorbing material, and after heating, cold pressing was carried out, An experiment was conducted.

Reference Example 1 The high-rigidity sound absorbing materials of Examples 1, 17 and 20 were installed in the vicinity of the engine of a vehicle, and the engine was run to measure the sound pressure level for each frequency. It was possible to confirm that there was no omission and that there was a sound absorption effect that was almost the same as the result of acoustic excitation.

Reference Example 2 The high-rigidity sound absorbing materials of Example 1, Example 17, and Example 20 were installed closer to the intake side than the air cleaner of the intake system of the vehicle, and the engine was started to produce intake sound at each frequency. When the pressure level was measured, it was confirmed that the sound absorbing material did not come off and that the sound absorbing effect was almost the same as the result of the acoustic excitation.

Reference Example 3 The high-rigidity sound absorbing materials of Example 1, Example 17, and Example 20 were installed closer to the engine side than the air cleaner of the intake system of the vehicle, and the engine was turned on to produce sound pressure at each frequency. When the level was measured, it was confirmed that the sound absorbing material did not come off and that the sound absorbing effect was almost the same as the result of the acoustic excitation.

Test Examples The following experiments were carried out on the high-rigidity sound absorbing materials obtained in the above-mentioned examples, conventional examples and comparative examples.

Test Example 1 The high-rigidity sound absorbing material obtained by the method of each of the above-mentioned Examples and Comparative Examples was attached near a four-cylinder engine installed in a semi-anechoic chamber. With this system, an actual engine firing experiment was performed, sound pressure levels were measured at 1 m in four directions in the front, rear, left, and right of the engine and 1 m above the engine. The four positions were averaged and the sound without sound absorbing material was measured. The difference from the pressure level is displayed in dB for each frequency. At this time 50 ~
The average value is shown in Table 1, with 300 Hz as the low frequency, 300 to 500 Hz as the medium frequency, and 500 to 2 kHz as the high frequency.
It was noted in a few. The results of these tests are shown in Tables 1, 2, and 3.

[0101]

[Table 1]

[0102]

[Table 2]

[0103]

[Table 3]

From Table 1, the various high-rigidity sound absorbing materials prepared in the examples are lower in frequency (50 to 300H) than the conventional examples.
z), medium frequency (300 to 500 Hz), and high frequency (500 to 2 kHz), it was confirmed that it is a high-rigidity sound absorbing material that exhibits excellent sound absorbing characteristics, does not take up space, and has excellent mountability. .

Further, in the comparative example prepared with the specifications outside the specified range of the present invention, the sound absorbing performance in the particularly required low frequency and middle frequency regions (5d at low frequency as a judgment standard)
B, those having no silencing performance of 8 dB at medium frequency were considered as unacceptable. Further, in Examples 15 to 19 in which the core is provided and the rigidity is further increased, it is not possible to use a resonator having a feeling of rigidity lower than that of the high-rigidity sound absorbing material alone, and Example 2 in which a resonator is configured.
0 to 25 were disapproved when the effect when the resonator was attached was not significant. ), And it was confirmed that they could not be satisfied in terms of space (things that could not fit in the actual engine compartment of the vehicle were not allowed).

[0106]

As described above, according to the high-rigidity sound absorbing material of the present invention, it has excellent sound absorbing performance in the low frequency region of 500 Hz or less and sufficient sound absorbing performance in the high frequency region. It is possible to provide a compact sound absorbing structure that does not take up space.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a Helmholtz resonator.

FIG. 2 is a schematic view of a high-rigidity sound absorbing material.

FIG. 3 is a schematic diagram of a shape 1 of a high-rigidity sound absorbing material.

FIG. 4 is a schematic view of a shape 2 of the high-rigidity sound absorbing material.

FIG. 5 is a schematic diagram of the shape 3 of the high-rigidity sound absorbing material.

[Explanation of symbols]

1 volume part 1 2 volume part 2 3 Opening area S 4 neck length L 5 volume V 6 Volume 1 7 Volume 2 8 missing parts 9 High rigidity sound absorbing material 10 Missing part 11 High rigidity sound absorbing material 12 Missing part 13 High rigidity sound absorbing material

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G10K 11/162 F02B 77/13 F02M 35/12 G10K 11/16

Claims (6)

(57) [Claims] 1. A sound absorbing material made of a woven fabric or a non-woven fabric made of a fiber aggregate made of short fibers and / or long fibers, wherein the fibers constituting the sound absorbing material have a diameter of 10 to 40 μm.
made of polyester in the m range, 70% of this fiber
-100% by weight is a binder fiber having a double core portion and a surface portion in the cross-sectional direction, and the core portion has a high softening point and the surface portion has a low softening point, and the difference between the softening points is 20. ~
It is a fiber in the range of 150 ° C., the sound absorbing material as a whole has an average thickness of 3 to 30 mm, and an areal density of 200 to 2.0.
Highly rigid sound absorbing material characterized by being in the range of 00 g / m ² . 2. A laminated sound-absorbing material having a fiber aggregate on one or both sides of a core material of any material, wherein the thickness is 3 to 40% of the total thickness of the laminated sound-absorbing material. A high-rigidity sound absorbing material, characterized in that the sound absorbing material of is located on one side or both sides. 3. A plate-like sound absorbing material having at least one or more openings or missing portions in the range of 4 to 100 cm ² between a portion where the sound absorbing material is installed and the sound absorbing material. Depending on the ratio of the volume part 1 formed by (1) to the volume part 2 formed by the opening or the lacking part having the thickness of the sound absorbing material, the resonance of the system is in the range of 50 to 450 Hz. The high-rigidity sound absorbing material according to claim 1, which can be formed. 4. The high-rigidity sound absorbing material according to claim 1, which is used as a component in an engine room for reducing a sound pressure in the engine room of a vehicle. 5. The air intake system duct is installed in a part of the air intake system in order to reduce the intake air intake noise of the vehicle.
The high-rigidity sound absorbing material according to any one of 3 to 3. 6. A high-rigidity sound-absorbing material as claimed in any one of claims 1 to 5.
A method of manufacturing, which comprises opening polyester fibers, mixing them, making them into a bulky shape by a card-type nonwoven fabric process or an air-laying nonwoven fabric process, and heating them in a far-infrared oven or a hot-air oven, and then a roll processing process or needle punching. The thickness is adjusted in the step to make a non-woven sound absorbing material, and the non-woven sound absorbing material is pre-softened in a temperature range of 150 to 250 ° C., and then the formed sound absorbing material layer is press-molded into a required shape in a cold press mold. A method for manufacturing a high-rigidity sound absorbing material, which is characterized by the above.