Lightweight noise absorbing material and substrate having the same attached thereto

Abstract

The present disclosure relates to a lightweight noise absorbing material and a substrate having the same attached thereto, and more particularly, to a lightweight noise absorbing material providing lightweight and excellent noise absorption performance compared to existing noise absorbing materials by including a triple thin fiber layer in which upper and lower fine fiber layers are stacked respectively on upper and lower surfaces of a fibrous non-woven fabric, and a substrate having the lightweight noise absorbing material attached thereto.

Claims

1. A lightweight noise absorbing material for low frequency noise absorption in the range of 2,000 to 3,000 Hz comprising: a triple thin fiber layer including a fibrous non-woven fabric formed of fibers having an average diameter of 10 to 20 μm; upper and lower fine fiber layers formed of fibers having an average diameter of 2 to 6 μm and stacked respectively on upper and lower surfaces of the fibrous non-woven fabric; and a block layer stacked beneath the lower fine fiber layer and having a plurality of blocks arranged with a predetermined interval there between to form air gaps between the blocks, wherein the block layer is formed of a felt or foam material, and wherein the triple thin fiber layer has a weight per unit area of 30 to 75 g/m.sup.2, a thickness of 0.2 to 1 mm, and air resistivity of 1,000,000 to 5,000,000 Pa.Math.s/m.sup.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and other advantages of the present disclosure may be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a schematic cross-sectional view showing a lightweight noise absorbing material including a triple thin fiber layer according to an embodiment in the present disclosure;

(3) FIG. 2 is a schematic cross-sectional view showing the lightweight noise absorbing material further including a block layer stacked beneath the thin fiber layer of FIG. 1;

(4) FIG. 3 is a schematic cross-sectional view showing a state in which the lightweight noise absorbing material of FIG. 1 is attached to a substrate;

(5) FIG. 4 shows graphs comparing noise absorption performance of the lightweight noise absorbing material of FIG. 1 and those of existing noise absorbing materials;

(6) FIG. 5 shows graphs illustrating noise absorption performances of the lightweight noise absorbing material of FIG. 1 depending on air resistivity; and

DESCRIPTION OF SPECIFIC EMBODIMENTS

(7) According to an embodiment in the present disclosure, a lightweight noise absorbing material and a substrate having the same attached thereto is hereinafter described in detail with reference to the accompanying drawings.

(8) The accompanying drawings in the present disclosure may be exaggerated to clearly distinguish the present disclosure from the prior art and to assist in understanding of the technique disclosed in the present disclosure. Further, the following terminologies are defined in consideration of the functions in the present disclosure and may be construed in different ways by the intention of users and operators. Therefore, the definitions thereof should be construed based on the contents throughout the specification. Meanwhile, exemplary embodiments of the present disclosure are only examples of the components disclosed in the claims and the scope of present disclosure is not limited thereto. The scope of the present disclosure should be interpreted based on the technical idea suggested in the entire specification of the present disclosure.

First Exemplary Embodiment

(9) Hereinafter, a lightweight noise absorbing material including a thin fiber layer in accordance with a first exemplary embodiment in the present disclosure is described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing a triple thin fiber layer 110. The thin fiber layer 110 includes a fibrous non-woven fabric 111 and the upper and lower fine fiber layers 112 and 113 stacked respectively on upper and lower surfaces of the fibrous non-woven fabric.

(10) The fibrous non-woven fabric 111 is formed of fibers having an average diameter of 10 to 20 μm, and the upper and lower fine fiber layers 112 and 113 are formed of fibers having an average diameter of 2 to 6 μm and stacked respectively on the upper and lower surfaces of the fibrous non-woven fabric 111.

(11) The fibers included in the fibrous non-woven fabric 111 and the upper and lower fine fiber layers 112 and 113 may be formed of any polymer which may be used as a common noise absorbing material, and may generally be at least one selected from the group consisting of polyethylene, polypropylene, polyamide, polyamide copolymer, polyurethane, polyester, polyester copolymer, polyvinyl acetate and polyvinyl alcohol.

(12) The fibrous non-woven fabric 111 serves to increase physical property (tensile strength) and air resistivity of the thin fiber layer 110. When the fibers included in the fibrous non-woven fabric 111 have the average diameter of 10 to 20 μm, the air resistivity may be increased to a certain level or higher.

(13) The upper and lower fine fiber layers 112 and 113 serve to increase the air resistivity and simultaneously, to convert sound wave energy into heat or vibration energy. The fibers included in the upper and lower fine fiber layers 112 and 113 may be formed to have the average diameter of 2 to 6 μm. The reason is that in the above range, the air resistivity may be increased by weight to increase noise absorption performance.

(14) The thin fiber layer 110 may be formed to have a weight per unit area of 30 to 100 g/m.sup.2 and a thickness of 0.2 to 1 mm. The reason is that in the above range, the thin fiber layer 110 may have excellent noise absorption performance with respect to a price thereof.

(15) In addition, the thin fiber layer 110 may be formed to have air resistivity of 1,000,000 to 5,000,000 Pa.Math.s/m.sup.2. The reason is that in the above range, the thin fiber layer 110 may have better noise absorption performance as seen from FIG. 5.

(16) The thin fiber layer 110 according to the first exemplary embodiment in the present disclosure has higher air resistivity than that of a single-layered fiber layer as seen from a result of a comparison experiment in FIG. 4. For reference, FIG. 4 shows graphs which illustrate an experiment comparing noise absorption performance of the thin fiber layer 110 according to the present disclosure and those of existing single-layered fiber layers. In the present experiment, the thin fiber layer 110 according to the present disclosure is a thin fiber layer formed by stacking the upper and lower fine fiber layers 112 and 113 on the upper and lower surfaces of the fibrous non-woven fabric 111, and having an area density of 70 g/m.sup.2, in which the upper and lower fine fiber layers 112 and 113 include fibers having an average diameter of 3 μm and formed of polypropylene (PP), and the fibrous non-woven fabric 111 has an average diameter of 30 μm and is formed of polyethylene terephthalate (PET). As comparative examples, the existing fiber layers are formed only of PP and have an average diameter of 3 μm and respective area densities of 45 g/m.sup.2, 65 g/m.sup.2 and 75 g/m.sup.2. In the present experiment, for measuring the noise absorption performances, the thin fiber layer 110 of the present disclosure and the existing fiber layers are fixed to an impedance tube to have an air gap thickness of 10 mm, and then the noise absorption performances thereof are measured using an in-tube method.

(17) As a result, even though a noise absorbing material having a higher area density generally has a more improved noise absorption performance, a lightweight noise absorbing material 100 [having the area density of 70 g/m.sup.2] according to the present disclosure is confirmed to have excellent noise absorption performance as compared to those of existing noise absorbing materials [having the area density of 75 g/m.sup.2] in a low frequency band of 3,000 Hz or less. In particular, the low frequency band belongs to a noise frequency region generated when a vehicle is traveling, and thus further excellent noise absorption effect may be achieved when the thin fiber layer 110 is used in an interior of the vehicle.

Second Exemplary Embodiment

(18) Hereinafter, a lightweight noise absorbing material 100 in accordance with a second exemplary embodiment in the present disclosure is described with reference to FIG. 2. FIG. 2 shows that a block layer 130 is stacked beneath the thin fiber layer 110 of the first embodiment described above. The block layer 130 is stacked beneath a lower fine fiber layer 113 of the thin fiber layer 110 and has a plurality of blocks 131 arranged with an equal or unequal interval therebetween. When the lightweight noise absorbing material 100 is attached to a substrate 200, air gaps 300 are formed between the blocks 131 included in the block layer 130. As a result, as compared to an existing noise absorbing material having a single-layer and the same thickness, the lightweight noise absorbing material 100 may have a further reduced area density, and accordingly, may have advantages of light weight, reduced cost, and excellent noise absorption performance. The block 131 may be formed of a felt or polymer foam material.

Third Exemplary Embodiment

(19) Hereinafter, a lightweight noise absorbing material 100 in accordance with a third exemplary embodiment in the present disclosure is described with reference to FIG. 3. As described above, FIG. 3 shows a separately designed substrate 200′ formed to have air gaps when the lightweight noise absorbing material 100 of the present disclosure is attached to the substrate 200′ as described above. FIG. 3 shows a state in which the lightweight noise absorbing material 100 including the thin fiber layer 110 of the first embodiment is attached to the substrate 200′. The substrate 200′ includes a plurality of support protrusions 210 protruding outwardly from the substrate. The lightweight noise absorbing material 100 is attached to the substrate 200′ and thereafter, air gaps 300 are formed between the support protrusions 210. The support protrusions 210 may have a height of 4 to 20 mm and may be formed in a process of injecting the substrate 200′ or integrated with a flat substrate through a separate bonding process.

(20) As described above, the lightweight noise absorbing material and the substrate having the same attached thereto according to the present disclosure may have the following effects:

(21) 1. The triple thin fiber layer according to the present disclosure may have higher air resistivity than that of the single-layered noise absorbing material having the same area density and accordingly, may provide the excellent noise absorption performance.

(22) 2. When the block layer having the plurality of blocks arranged with a predetermined interval therebetween is further stacked beneath the thin fiber layer, the dispersion path of the sound wave may be increased even though the area density of the noise absorbing material is not significantly increased and thus, the noise absorption performance may be further improved.

(23) 3. The substrate may include the plurality of support protrusions protruding outwardly from the substrate to have the air gaps formed by the support protrusions between the substrate and the lightweight noise absorbing material. Therefore, when the lightweight noise absorbing material of the present disclosure is attached to the substrate, the dispersion path of the sound wave may be increased and thus, the noise absorption performance may be further improved.

(24) The exemplary embodiments in the present disclosure described above and illustrated in the drawings should not be interpreted as limiting the technical idea of the present disclosure. The scope of the present disclosure is limited only by the accompanying claims, and those skilled in the art may modify and change the technical idea of the present disclosure in various forms. Therefore, it is obvious to those skilled in the art that these alterations and modifications fall within the scope of the present disclosure.