JP2003345362A - Sound absorbing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing material superior to conventional sound absorbing materials in sound absorbing effect. <P>SOLUTION: In the sound absorbing material in which cover sheets are superposed on both surfaces of a base sheet and are fixed by a proper fixing means, the base sheet is made of nonwoven fabric of extra fine fiber manufactured by a melt blown method and the cover sheet is made of nonwoven fabric of long fiber and further these sheets are superposed in a nonadhesive state. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like sound absorbing material, and is used for a gasoline tank cover, an air conditioner cover, a hood inner wall covering material, and other parts of a transportation equipment, etc., which require a sound absorbing effect.

[0002]

2. Description of the Related Art As a sound absorbing material of this type, in the past, (1) an average diameter of about 2 μm was produced by the melt blown method.
Of a non-woven fabric in which polypropylene ultrafine fibers of (1) and polyester short fibers having an average diameter of about 25 μm for thickness are integrated (Conventional example 1), (2) Non-woven fabric made of polyester long fibers (Conventional example 2) Are known, and each has a sound absorbing effect.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sound absorbing material which has a better sound absorbing effect than the conventional sound absorbing material described above.

In order to achieve this object, the inventor conducted extensive research and completed the present invention.

[0005]

In a sound absorbing material according to the present invention, a cover sheet is placed on both sides of a base sheet, and the base sheet is an ultrafine material made by a melt blown method in which the cover sheet is fixed by appropriate fixing means. Since it is a nonwoven fabric made of fibers, and the cover sheet is a nonwoven fabric made of long fibers, and these are stacked in a non-adhesive state, as shown in Graph 2, the sound absorbing effect is higher than that of the conventional sound absorbing material. Will improve synergistically.

The base sheet is a non-woven fabric (conventional example 1) in which polypropylene ultrafine fibers having an average diameter of about 2 μm and polyester short fibers having an average diameter of about 25 μm, which are produced by a melt blown method, are integrated. If the cover sheet is a non-woven fabric made of polyester long fibers (conventional example 2), the sound absorbing material according to the present invention can be easily manufactured.

[0007]

1 is a sectional view of a sound absorbing material according to the present invention, and FIG. 2 is a graph showing a sound absorbing effect of the sound absorbing material.

In FIG. 1, 10 is a sound absorbing material according to the present invention, and 20 is a base sheet thereof. This base sheet 20 is a non-woven fabric made by melt blown method, which is made by integrating polypropylene ultrafine fibers with an average diameter of about 2 μm and polyester short fibers with an average diameter of about 25 μm to obtain a thickness, and a large amount of air between fine fibers. It has elasticity because it has layers.

The physical properties of the non-woven fabric forming the base sheet 10 (test method in parentheses) are 10 mm (0.
(Measured under a load of 002 psi), weight 200 g / m ² , water content 0.
4% (JIS L3203), thermal conductivity (0.0342W / mK) (ASTM C
518 and JIS A1412, using Rapid K manufactured by Holometrix) (average temperature: 22.5 ° C), heat resistance is 120 ° C, 2000
No change in sound absorption coefficient with time (measured according to ASTM E1050), tensile strength: longitudinal: 9.3N (0.95kgf), lateral: 10.0 N
(1.02kgf) (Sample width: 50MM, gripping interval: 200mm,
Tensile speed: 200mm / min), flame retardancy is FMVSS No. Equivalent to 302 (FMVSSNo.302), composition is polypropylene: 65%, polyester: 35%. The non-woven fabric forming the base sheet 20 corresponds to the so-called conventional example 1, and as an example thereof,
There exists Thinsulate (trademark) manufactured by Sumitomo 3M Limited.

Next, 30 and 30 are cover sheets. The cover sheets 30, 30 are laminated on both sides of the base sheet 20 in a non-adhesive state. This cover sheet 30 is a non-woven fabric made of polyester filaments and has a thickness of about 0.2 to 0.3 mm.
It is a sheet having flexibility.

The physical properties of the nonwoven fabric forming the cover sheet 20 (test methods in parentheses) are as follows. The measuring method is based on JIS L1906. However, the chuck spacing is 100, the sample thickness is 0.28 mm, and the tensile test conditions are as shown. (1). Tensile strength (N / 5cm) Vertical …… 205 Horizontal …… 80 (2). Elongation rate (%) Vertical …… 40 Horizontal …… 35 (3). Tear strength (N) (Pendulum method) Vertical) ...... 9.2

Further, the composition is such that the main components are polyester (polyethylene terephthalate, modified polyester) and a trace amount of carbon black and titanium oxide as a colorant, and no adhesive or finishing oil agent is used.
The non-woven fabric forming the cover sheet 30 corresponds to the so-called conventional example 2, and an example thereof is Spunbond (trademark) manufactured by Unitika Ltd.

The cover sheets 30 and 30 are the base sheets 20.
The heat source temperature in the press is set to 120 ° C on the upper surface and 130 ° C on the lower surface, and the mold temperature is kept at 110 ° C, and the press pressure is 3 to 10 kgf / cm. ^2. Hot press molding (corresponding to "appropriate fixing means" of the present invention) 50 with pressing time of 6 to 8 seconds. It is also possible to provide the thermocompression bonding portion 51 in a spot shape and to provide a cross-shaped notch through which the mounting member penetrates in this portion.

Next, in FIG. 2, a polygonal line A indicates the sound absorption coefficient of the sound absorbing material 10 according to this embodiment, a polygonal line B indicates the sound absorption coefficient of the sound absorbing material according to the conventional example 1, and a polygonal line C indicates the sound absorption coefficient of the conventional example 2. It shows the sound absorption coefficient of a material (a state in which two sheets are stacked). The measuring instrument is a normal incidence measuring instrument, and the measuring temperature is 27 ° C. The size of the sample is 90φ.

As is clear from this graph, the sound absorption coefficient of the sound absorbing material 10 according to the present invention is not simply the sound absorption coefficient of the conventional example 1 and the sound absorption coefficient of the conventional example 2 (a state where two sheets are stacked). However, it exhibits a unique and excellent sound absorption coefficient at about 300 Hz to 1800 Hz. In particular, it exhibits an outstanding sound absorption coefficient at 600 Hz to 1600 Hz.

[0016]

The sound-absorbing material according to the present invention is a sound-absorbing material in which cover sheets are superposed on both sides of a base sheet and fixed by appropriate fixing means, wherein the base sheet is a non-woven fabric made of ultrafine fibers produced by the melt blown method. In addition, since the cover sheet is a non-woven fabric made of long fibers and these are stacked in a non-adhesive state, as shown in the graph of FIG. 2, the sound absorbing effect is more synergistic than that of the conventional sound absorbing material. Improve to.

Therefore, the use value of the sound absorbing material is increased as compared with the conventional one, and the range of use thereof is expanded.

The base sheet is a non-woven fabric (conventional example 1) in which polypropylene ultrafine fibers having an average diameter of about 2 μm and polyester short fibers having an average diameter of about 25 μm, which are made by a melt blown method, are integrated. If the cover sheet is a non-woven fabric made of polyester long fibers (conventional example 2), the sound absorbing material according to the present invention can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a sound absorbing material according to the present invention.

FIG. 2 is a graph showing a sound absorbing effect of the sound absorbing material.

[Explanation of symbols]

10… Sound absorbing material 20… Base sheet 30… Cover sheet 50… Thermo-compression bonding part (appropriate fixing means)

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Claims (2)

[Claims] 1. A cover sheet is laminated on both sides of a base sheet,
In the sound absorbing material fixed by an appropriate fixing means, the base sheet is a non-woven fabric made of ultrafine fibers made by a melt blown method, and the cover sheet is a non-woven fabric made of long fibers, and these are non-adhesive. A sound absorbing material characterized by being stacked in a state. 2. The sound-absorbing material according to claim 1, wherein the base sheet is a polypropylene ultrafine fiber having an average diameter of about 2 μm, which is produced by a melt blown method, and an average diameter of about 25 to give a thickness.
A non-woven fabric that integrates polyester short fibers of μm,
Moreover, the sound absorbing material, wherein the cover sheet is a non-woven fabric made of polyester long fibers.