JP3140610B2 - High rigidity sound absorbing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sound insulation of automobile interior materials.
For interior sound absorbing material with high functionality such as sound absorption, especially used for parts that require high rigidity to maintain shape, such as floor insulator, door trim, head lining, trunk rim, dash insulator, etc. High-rigid sound absorbing material.

[0002]

2. Description of the Related Art As automobiles become more sophisticated and higher in performance, it is now necessary to provide quietness in the interior of the vehicle. As a result, the interior materials for automobiles have become more sophisticated. In particular, there have been few interior materials having additional functions such as sound absorption and sound insulation, and it has generally been considered that the interior materials are inexpensive. These are felts that use thermosetting binders such as phenolic resins for wood boards and recycled fibers,
Alternatively, a thermoplastic resin containing an inorganic fiber such as a glass fiber was hot-pressed or cold-pressed. However, of course, these have little additional performance, and further have the following disadvantages in the conventional interior materials.

[0003] First, there is no recyclability.
This is because the core material has a multilayer structure, and the material for each layer is different.

Second, phenolic resins conventionally used to increase rigidity emit an unpleasant odor.
Unpleasant odors are considered to be a serious problem in practical use because they are used as interior materials for automobiles, and alternative materials have been demanded.

Third, when the conventional material is assembled to a vehicle, there is a high possibility that abnormal noise is generated which interferes with the rigid panel of the vehicle body. In order to solve this, an operation of sandwiching a soft non-woven fabric or urethane foam on the interference surface between the interior core material and the panel was necessary, which was labor intensive and uneconomical.

[0006] In addition, in the case of conventional automobile interior materials having sound absorbing and sound insulating performance, it is very difficult to maintain the shape with only the sound absorbing and insulating material due to insufficient rigidity. In this case, the sound absorbing and insulating performance was significantly reduced. Further, as another method, a method of maintaining a shape of a wood board, a material obtained by impregnating a recycled fiber with a thermosetting resin or the like in order to maintain a shape, and thereby maintaining a shape of a sound absorbing and insulating material is known. At present, the effect of the sound absorbing and insulating material has been reduced.

[0007]

Under these circumstances, it has been attempted to obtain a shape retention and sound absorption / insulation performance of a conventional material as a sandwich structure composed of three layers of a panel, a felt, and a skin. However, sufficient performance could not be obtained because a panel was used to maintain the shape. In addition, when the interior material is formed of only a conventional sound absorbing material or a material having a high function, the rigidity is insufficient, and there is a problem in actually using the interior material in a vehicle in terms of shape retention.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to consider the above problems in order to realize a quiet cabin space in view of such conventional technology, and to have higher sound absorbing and insulating performance and higher rigidity. In order to develop a sound absorbing material, we will provide a high rigidity sound absorbing material used in automotive interior materials with excellent sound absorbing and insulating performance by using a fiber aggregate obtained by fiber blending that can achieve high sound absorption and high rigidity. is there.

[0009]

Means for Solving the Problems The present inventors have analyzed the function of the fiber assembly and the performance of the fiber assembly and found a method for improving the sound absorbing performance and rigidity, and have completed the present invention. In order to solve the above-mentioned problems, the composition of the fiber composition is made to be able to achieve both sound absorbing and insulating performance and rigidity as compared with the conventional one. That is, a high-rigidity sound-absorbing material could be realized by giving a characteristic to the mixing ratio of the high softening point fiber and the low softening point fiber.

Accordingly, the present invention provides a synthetic fiber staple having a fineness of 15 denier or less having an average apparent density of 0.02 to 0.8 g /
A high-rigidity sound-absorbing material consisting of a fiber aggregate molded to a size of ³ cm3 and having a fineness of 1.5 as the main fiber among the fibers used.
20 to 70% by weight of a high softening point fiber (fiber A) having a denier of 0 to 3%, 0 to 50% by weight of a fiber having a high softening point (fiber B) having a denier of 2 to 15 denier, and 1.5 to 3 denier. The present invention relates to a high-rigidity sound-absorbing material characterized by using 30 to 80% by weight of a low softening point fiber (fiber C) having a softening point lower by at least 20 ° C. than a softening point fiber.

In the present invention, the fineness of the synthetic fiber staple is limited to 15 deniers or less because fibers having a thickness larger than this have a large surface area / cross-sectional area value and cannot efficiently absorb sound energy. Yes, preferably 6 denier or less. 0.02 g / cm average apparent density
^The reason for setting it to ³ or more is that if it is less than 0.02 g / cm ³ , the proportion of fibers in the same volume becomes small, sufficient airflow resistance cannot be obtained, and sound absorption performance is not sufficient. The reason for limiting the average apparent density to 0.8 g / cm ³ or less is that the density is
In the state higher than 0.8 g / cm ³ , the movement of the fiber itself is restricted, and it is not possible to expect sufficient sound absorption, and the fiber assembly is too hard, and the fiber assembly is no different from using conventional Hanel. This is because there is no reason to use the body. As the fibers used, thermoplastic polymers such as polyamide, copolymerized polyamide, polyester, copolymerized polyester, polyacrylonitrile, copolymerized polyacrylonitrile, polyolefin, polyvinyl chloride, polyvinylidene chloride, and polyclar are used alone, mixed or composited. Fibers obtained by spinning are exemplified. Among the fiber types, polyester-based fibers are optimal in view of high crystal melting point (T _m ) and relatively low cost, but are not particularly limited.

The necessity of using 1.5 to 3 denier high softening point fiber as the fiber A is that when a fiber having a large diameter is used, the value of the surface area / cross-sectional area becomes large and the sound energy cannot be efficiently absorbed. The most efficient is 1.5 to 3 denier fiber. In order for this fiber to exhibit an effect on sound absorption, it is preferably required to be at least 20% by weight, more preferably at least 30% by weight. However, when using more than 70% by weight,
Since the fiber diameter is small and the rigidity of the fiber itself is low, high rigidity as a fiber aggregate cannot be obtained. Therefore, the content is preferably 70% by weight or less, more preferably 60% by weight or less.

Further, the necessity of using a high softening point fiber of 2 to 15 denier as the fiber B is expected to improve the sound absorbing performance when only a fiber having a small fineness is used, but the rigidity of the fiber itself is low. In some cases, the rigidity of the resulting fibrous polymer cannot be obtained. Therefore, by using a high softening point fiber having a fineness of 2 to 15 denier, high rigidity can be obtained as a fiber aggregate. However, if it is used in an amount of more than 50% by weight, sufficient airflow resistance cannot be obtained, and the sound absorbing performance is not sufficient.
When a fiber having a fineness exceeding denier is used, a fiber surface area per unit weight becomes small, so that sufficient sound absorbing performance cannot be obtained. Therefore, a fiber having 15 denier or less is used. In addition to the high softening point fiber, the fineness of fiber C is
1.5 to 3 denier and at least 20% higher than the high softening point fiber
As for the temperature, 30 to 80% by weight of a low softening point fiber having a low softening point is used. The low softening point fiber is used as a binder used to fix the shape of the fiber assembly, and is preferably a heat-fusible fiber or a short fiber of a heat-fusible conjugate fiber.
When a high softening point fiber is used in a sufficient amount of a low softening point fiber (hereinafter referred to as a binder fiber) to be used as a binder, high rigidity can be maintained by that. There is no particular limitation.

In the present invention, the high softening point fiber is preferably a polyester fiber, and the low softening point fiber is a modified polyester fiber, for the purpose of solving the problem of recyclability. At present, polyester fiber is very often used as a skin material in interiors, and since the skin and base material are all made of polyester, there is no need to separate materials at the time of recycling. Therefore, there is an advantage that energy recycling by combustion or the like is easy and heat molding can be performed again.

The binder is preferably made of heat-fusible fibers or short fibers of heat-fusible conjugate fibers. This is because the mixing of the binder and the fibers is made more uniform and the fiber aggregate is used. In order to maintain the shape of the resin more firmly, when powdered resin is used, the binder is likely to be locally hardened, and when solvent-based resin is used, it adheres uniformly to the main fibers with low fineness and fibers This is because the diameter may be increased. It is preferable to use a conjugate fiber as the fiber B of the main fiber, but this is because when all the fibers used in the fiber assembly are composed of regular fibers,
The entanglement of the fibers and the entanglement of the cards are insufficient, and the cohesion of the fibers and the delamination between the cards occur. Therefore, by using the conjugate fiber, the entanglement between the fibers is provided, and the shape retention property is provided. By using conjugate fibers, it is possible to maintain the shape during heat molding and prevent sagging. However, if it is used in an amount of more than 50% by weight, the sound absorbing performance is inferior to that of the regular fiber. Further, use at less than 10% by weight is inferior in shape retention due to insufficient absolute amount, so use at 10% by weight or more is desirable.

For the above reasons, the most desirable sound absorbing material is a fiber having a fineness of 1.5 to 1.5 as a main fiber for enhancing sound absorbing performance.
3 to 60% by weight of fiber A of 3 denier, 10 to 50% by weight of fiber B made of conjugate fiber of 2 to 15 denier or less in terms of sagging prevention and 20 to 60% by weight, The binder used to fix the shape is a heat-fusible fiber or a heat-fusible conjugate short fiber, and the low softening point fiber of the fiber C having a fineness of 1.5 to 3 denier is 30 to 70. Fiber A, B,
C.

By setting the cross-sectional shape of the main fiber A to be a non-circular cross-sectional shape, it is possible to positively absorb sound energy. Here, the irregular cross-section refers to a fiber having a cross-sectional shape such that the outer circumference of the fiber is longer than a circular outer circumference equivalent to the fiber step area, and is flat, a convex polygon such as a triangle, a Y-shape, a cross-shape, or the like. A cross section of a concave polygon such as a star or the like, or an ultrafine fiber constituted by dividing fibers is included.
However, those having a surface on the inner surface of the fiber such as a hollow fiber do not include the inner surface.

Here, assuming that the fiber cross-sectional area of the main fiber A is S, the circle equivalent radius is given by the following equation.

(Equation 1) The irregular cross-section fiber referred to herein means a fiber whose outer periphery is larger than 2πr by 20% or more, that is, a fiber which satisfies L ≧ 1.2 × (2πr) when the peripheral length is L. For example, in the case of an equilateral triangle, the outer circumference is 28% larger. In the present invention, when such a modified cross-section fiber is used as the fiber A, it is preferable to use 20 to 60% by weight. The reason why the cross-sectional shape is effective for sound absorption is that the surface area of the fiber increases due to the large outer circumference, and the large area facilitates multiple reflection of sound, and also increases the contact area with air I do. Further, it is conceivable that friction between the fibers is more likely to occur because the contact surface between the fibers is wide. As a result, the direction of the force in each minute region of the fiber assembly is dispersed, and a force such as bending or tension is applied to the fiber, so that the vibration energy of air can be efficiently returned to the energy of the fiber. For these reasons, it can be seen that the cross-sectional shape is more effective for sound absorption.

Further, the fiber assembly according to the present invention is preformed into a flat fiber assembly, laid in a mold,
A compact can be obtained by heating and compressing this. The molding temperature shown here is a temperature at which molding can be actually performed. If the temperature is 260 ° C. or more, the fiber may partially melt due to the combination with the melting point and is not suitable. On the other hand, if the temperature is 70 ° C. or lower, the softening point of the binder is not reached, and the bonding between the fibers is insufficient.

[0020]

The present invention will be described below with reference to Examples, Comparative Examples and Test Examples. The fiber A used in the examples is a polyester having a triangular cross section, the fiber B is a polyester conjugate fiber, and the fiber C is a core-sheath structured polyester fiber having a low softening point (melting point at the center 220 ° C., melting point at the periphery 120 ° C.). Parts in the examples indicate parts by weight.

Example 1 20 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 10 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 70 parts of the cut 3 denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 2 20 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 50 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 3 50 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

[0024]

Example 4 60 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 10 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 5 50 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 10 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 40 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ³ and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 6 50 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 3-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 7 50 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 15-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ³ and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 8 50 parts of a short fiber obtained by cutting a 3-denier main fiber A to a length of 50 mm, 20 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Example 9 50 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 2-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

[0031]

Comparative Example 1 60 parts of a short fiber obtained by cutting a 6-denier main fiber A to a length of 50 mm, 10 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Comparative Example 2 10 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 60 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Comparative Example 3 40 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 40 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 20 parts of the cut 3 denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

COMPARATIVE EXAMPLE 4 Apparently, 80 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, and 20 parts of a 3-denier low softening point fiber C cut to a similar length were used as a binder. Charged in a mold to a density of 0.04 g / cm ³ , forming temperature 1
It was molded at 80 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Comparative Example 5 10 parts of a short fiber obtained by cutting 2 denier main fiber A to a length of 50 mm and 90 parts of 2 denier low softening point fiber C cut to the same length as a binder Charged in a mold to a density of 0.04 g / cm ³ , forming temperature 1
It was molded at 80 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

COMPARATIVE EXAMPLE 6 40 parts of a staple fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 30 parts of a 40-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 3-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ³ and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Comparative Example 7 40 parts of a short fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 40 parts of the cut 13-denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.04 g / cm ^3, and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

Comparative Example 8 50 parts of a staple fiber obtained by cutting a 2-denier main fiber A to a length of 50 mm, 20 parts of a 6-denier conjugate fiber B cut to a similar length, and a similar length Using 30 parts of the cut 2 denier low softening point fiber C as a binder, the mixture was charged into a mold so as to have an apparent density of 0.015 g / cm ³ and molded at a molding temperature of 180 ° C. to obtain a fiber aggregate having a thickness of 25 mm.

[0040]

Test Example The fiber aggregates obtained in Examples 1 to 9 and Comparative Examples 1 to 8 were measured for the amount of deflection under heat and the sound absorption coefficient at normal incidence in accordance with the following measuring method. Are shown in Table 1 together with Measuring method 1 (Measurement of deflection during heating) The fiber aggregate obtained by the method of the above example and comparative example was cut into 300 × 300 mm and 290 × 290 mm
4 mm fixed on each side with double-sided tape with a width of 5 mm, a load of 5 g / cm ² was applied to the center of the sample, and left at an orb atmosphere temperature of 90 ° C. for 3 hours. The amount of deflection was measured. Measurement Method 2 (Measurement of Normal Incidence Sound Absorption Coefficient) The fiber aggregates obtained by the methods of the above Examples and Comparative Examples were measured based on JIS 1405-1963 “Method of measuring normal incidence sound absorption coefficient of building material by pipe method”. Sample size diameter 100mm, measurement area 125-1.6Hz.

[0042]

[Table 1]

[0043]

As described above, the present invention provides a quiet cabin by using 20 to 70% by weight of fiber A, 0 to 50% by weight of fiber B, and 30 to 80% by weight of fiber C. In order to realize a space, it is possible to provide a sound absorbing material having higher sound absorbing and insulating performance and higher rigidity,
It is possible to provide a high-rigidity sound-absorbing material used for an interior material for automobiles having excellent sound-absorbing and insulating performance by using a fiber aggregate obtained by blending fibers that can achieve high sound absorption and high rigidity.

Continued on the front page (72) Inventor Hiroki Nagayama 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Hiroshi Sugawara 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56 References JP-A-1-148860 (JP, A) JP-A-2-95838 (JP, A) JP-A-6-238791 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) D04H 1/00-18/00 B32B 1/00-35/00 B60R 13/02 B60R 13/08

Claims (2)

(57) [Claims] 1. A high-rigidity sound-absorbing material comprising a fiber aggregate formed by molding three types of synthetic fiber staples, wherein a high softening point fiber having a fineness of 1.5 to 3 denier is used as a main fiber among fibers used. Fiber A) 20 to 60% by weight and fineness of 2
10 to 15% by weight of a high softening point conjugate fiber (fiber B) having a softening point of 1.5 to 3 denier and a softening point lower than that of the high softening point fiber by at least 20 ° C. C) A high-rigidity sound-absorbing material comprising a fiber aggregate formed by molding 30 to 70% by weight to an average apparent density of 0.02 to 0.8 g / cm ³ . 2. In the fiber assembly, the high softening point fiber is a polyester fiber, and the low softening point fiber is a modified polyester having a core-sheath structure in which the peripheral melting point is lower than the central melting point by 20 ° C. or more. The sound-absorbing material according to claim 1, wherein the sound-absorbing material is made of a conjugate fiber or a low-melting polyester fiber.