JPH10232681A - Sound absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect a fiber stack together with a resin-made base material and recycle it by composing the sound absorbing member of a base material made of thermoplastic resin and the fiber stack formed of fiber which is laminated on the base material surface and of the same material with the base material, and uniting the fiber stack and base material at least partially by depositing. SOLUTION: This member consists of the base material 1 made of thermoplastic resin and the fiber stack 2 formed of fiber which is laminated on the surface of the base material 1 and of the same material with the base material 1, and the fiber stack 2 and base material 1 are deposited in one body at least partially. Thus, the base material 1 and fiber stack 2 are formed of thermoplastic resin of the same material and then deposited in one body without using an adhesive or both-sided adhesive tape. Therefore, even when the base material 1 and fiber stack 2 are collected in one body without being separated, no foreign n material is mixed, so reproduced articles with excellent characteristics can be obtained. Woven fabric, knitted fabric, or knitted cords are usable as the fiber stack 2, but nonwoven fabric is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing member which is joined to the back of a pillar or door trim of an automobile and suppresses noise by absorbing a sound transmitted through the inside of a door or a vehicle body frame to enter a vehicle interior. More particularly, it relates to a recyclable sound absorbing member.

[0002]

2. Description of the Related Art In order to prevent noise transmitted through the interior of a door or a vehicle body frame and entering a vehicle interior, the back of resin parts such as automobile pillars and door trims is conventionally provided with a fiber assembly such as felt or urethane foam. Etc. are pasted. Specifically, as shown in FIG. 4, a fiber assembly 100 made of anti-haired felt is bonded to a base material 200 made of a resin component through an adhesive layer 300 such as an adhesive or a double-sided adhesive tape.
To form a sound absorbing member. The sound energy that has entered the holes between the entangled fibers in the fiber assembly 100 is gradually attenuated due to the viscous resistance of air near the fibers and the vibration of the fibers themselves. Transmission of sound to the room can be suppressed.

[0003]

SUMMARY OF THE INVENTION In order to make effective use of resources on the earth, in the case of products manufactured from materials that can be melted and reused, such as thermoplastic resin products and glass products, after being recovered from waste, they are melted. New products are being recycled. Also in automobile parts, the names of raw materials are described in various resin members, and it is easy to sort the collected various resin members into the same material, which helps to promote recycling.

However, in the above-described conventional sound absorbing member, since the base material 200, the fiber assembly 100, and the adhesive layer 300 are made of different materials, and the fiber assembly 100 is not thermoplastic, it is difficult to collect and recycle the fiber assembly 100 as it is. Have difficulty. That is, although only the substrate 200 can be recycled, the number of steps for completely separating the substrate 200 and the fiber assembly 100 is extremely large. Further, in the state where the separation is incomplete and the adhesive or the fiber adheres to the base material 200, the use thereof is extremely limited because it is present as an impurity in the melted / recycled recycled product. Therefore, using a new base material 200 is inexpensive and avoids problems in performance, so that the sound absorbing member is often disposed of after use, and resources cannot be used effectively.

Also, a fiber assembly 10 made of anti-hair felt
Since 0 is relatively large in specific gravity, it cannot be said to be a preferable material from another viewpoint of reduction in fuel consumption due to weight reduction. Further, there is a problem that the man-hour and processing cost for joining the base material 200 and the fiber assembly 100 are large. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a lightweight and inexpensive sound-absorbing member that enables a fiber assembly to be integrally collected with a resin substrate and recycled. .

[0006]

According to a first aspect of the present invention, there is provided a sound absorbing member comprising a thermoplastic resin base material and fibers laminated on the base material surface and made of the same material as the base material. It consists of a fiber assembly, and the fiber assembly and the base material are at least partially welded and integrated.

[0007] A feature of the sound absorbing member according to the second aspect, which further characterizes the sound absorbing member of the first aspect, is that the fiber assembly is a nonwoven fabric shaped into a shape conforming to the surface shape of the base material. A feature of the sound absorbing member according to claim 3 that further characterizes the sound absorbing member of claim 2 is that the nonwoven fabric contains 10 to 40% by weight of binder fibers.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the sound absorbing member of the present invention, since the base material and the fiber assembly are made of the same thermoplastic resin, they are integrated by welding without using an adhesive or a double-sided tape. Have been. Therefore, even if the base material and the fiber assembly are collected as a unit without being separated, a recycled product having excellent characteristics can be obtained because there is no mixing of different materials.

In addition, since an adhesive or a double-sided tape is not required, the welding portion between the base material and the fiber assembly is only partial, and the number of joining steps is reduced, so that the cost can be reduced. The substrate in the present invention is not particularly limited as long as it is a recyclable thermoplastic resin, and various thermoplastic resins can be formed into a predetermined shape by various molding methods and used.

As the fiber assembly, one formed of a thermoplastic resin of the same material as the base material is used. The fiber aggregate may be a woven fabric, a knitted fabric, or a braided cord, but is preferably a nonwoven fabric. By using a nonwoven fabric, the size and number of pores existing between the fibers are optimal for sound absorption, and the sound absorption characteristics are improved.

The fibers constituting the fiber assembly have a fineness of 1 to 3
It is desirable that the fibers be mainly composed of D (denier) fibers. When the fineness of the fiber is less than 1D, it is difficult to secure the thickness of the sound absorbing member within a predetermined weight, and when the thickness of the fiber assembly is increased to secure the sound absorbing characteristics, a large amount of fiber is required. Cost and weight increase. On the other hand, when the fineness exceeds 3D, the volume of pores between fibers increases and the number decreases, and the sound absorption characteristics deteriorate.

The apparent density of the fiber assembly is 0.0
It is desirably in the range of 2 to 0.10 g / cm ³ .
If the apparent density is less than 0.02 g / cm ³ , the volume of pores between the fibers becomes large, so that the sound absorbing property is reduced.
If it exceeds 10 g / cm ³ , it is difficult to secure the thickness of the sound absorbing member within a predetermined weight, and if the thickness of the fiber assembly is increased to secure the sound absorbing characteristics, a large amount of fibers is required, resulting in cost and weight. Increase.

It is desirable that the fiber assembly is formed in advance in a shape along the surface shape of the substrate. The shaping of the fiber assembly can be easily performed by heating the fiber assembly to a temperature higher than its thermal deformation temperature and cold pressing. Further, the fiber assembly according to the present invention is composed of thermoplastic resin fibers. Therefore, recycled fibers can be used for at least a part of the fibers constituting the fiber assembly. Recycled products are inferior to new products in color tone and appearance, so they are difficult to use for design parts and the like, but sound absorbing members like the present invention rarely appear on the outermost surface. In addition, since the sound absorbing properties are not affected even if the appearance quality is somewhat poor, global resources can be effectively used by actively using recycled fibers.

It is preferable that the fibers constituting the fiber assembly include binder fibers having a lower melting point than other fibers. When the fiber aggregate is shaped by heating at a temperature equal to or higher than the melting point of the binder fiber and lower than the melting point of the other fiber, only the surface of the binder fiber can be melted, and the other fiber is bonded via the binder fiber. As a result, the shaped shape is maintained, and the binder fiber can be used as a part of the fiber constituting the fiber assembly. Therefore, the holes between the fibers are less likely to be filled with the molten binder, the number of holes formed between the fibers is increased, and the volume of each hole is small and fine. Thereby, the sound absorption characteristics are improved.

It is desirable to use a binder fiber having a fineness of 2 to 4D. Although it is preferable that the fineness is smaller, if it is smaller than the other fibers, the strength for bonding the other fibers becomes small, and it becomes difficult to secure the rigidity. On the other hand, if the fineness exceeds 4D, the pores between the fibers may be closed, and the sound absorbing properties may be reduced.

The binder fiber contains 1
The content is preferably 0 to 40% by weight. 10 binder fibers
When the amount is less than the weight%, the strength for bonding other fibers becomes small, and it is difficult to secure rigidity. On the other hand, if it exceeds 40% by weight, the pores between the fibers may be closed, and the sound absorbing properties may be reduced. It is also preferable to use, as the binder fiber, a fiber whose inside is formed of a resin having a high melting point and whose outer layer is coated with a resin having a low melting point. By using such a two-layer fiber, the amount of fusion during heating can be further reduced, and the pores of the formed fibers are prevented from being closed, so that the sound absorbing properties are further improved.

In the sound absorbing member of the present invention, the base material and the fiber assembly are partially welded and integrated. The number of welding points is not particularly limited, and is preferably as small as possible within a range that can be handled. As a welding method, ultrasonic welding, vibration welding, heat welding, or the like can be used.

[0018]

The present invention will be specifically described below with reference to examples and comparative examples. (Embodiment) FIG. 1 shows a main part of a sound absorbing member according to an embodiment of the present invention. This sound absorbing member includes a pillar 1 made of polypropylene (PP) and a nonwoven fabric 2 made of PP bonded to the back surface of the pillar 1. The PP non-woven fabric 2 is integrally joined to the pillar 1 by a welded portion 20. Hereinafter, a method of manufacturing the sound absorbing member will be described, and the detailed description of the structure will be substituted.

[0019] and the 1PP fiber 70 wt% of the melting point of 170 ° C. in fineness 2D, and cotton mixing the first 2PP fiber 2 having a melting point of 130 ° C. and a 30% by weight fineness 3D, basis weight 400 g / m ² P
P nonwoven fabric 2 was formed. The PP nonwoven fabric 2 is heated at a temperature of 1
Heat to 50 ° C, immediately cold press, thickness 10m
m was formed into a predetermined shape. At this time, the surface of the second PP fiber was melted and acted as a binder, and the first PP fibers 1 were bonded together to complete the shaping. That is, as shown in an enlarged manner in FIG. 1, the surface of the second PP fiber 22 is melted by heat at the time of shaping, and the first PP fiber 2 near the second PP fiber 22 is formed.
1 fuses with the second PP fiber 22. As a result, the first PP
Since the fibers 21 are bonded via the second PP fibers 22, the PP nonwoven fabric 2 can be easily shaped into a predetermined shape, and the shaped state can be maintained.

Next, the pillar 1 previously formed into a predetermined shape is used.
Is prepared, and a nonwoven fabric 2 made of PP is ultrasonically welded to its back surface.
Were welded in a spot shape to form a welded portion 20. As a result, the PP nonwoven fabric 2 was integrally welded to the pillar 1, and a sound absorbing member was manufactured. Comparative Example FIG. 2 shows a sound absorbing member of a comparative example. This sound absorbing member is composed of a pillar 1 made of PP similar to that of the embodiment, and an anti-hair felt 3 joined to the back surface of the pillar 1.

The anti-hair felt 3 has a basis weight of 750 g / m ^{2 and} a thickness of 10 mm, which is the same as that of the PP nonwoven fabric 2. And it is joined to the pillar 1 by the double-sided tape 4. (Test / Evaluation) The sound absorbing members of the example and the comparative example were respectively mounted on a normal incidence sound absorption coefficient measuring device (microphone impedance), and the normal incidence sound absorption coefficient was measured for each frequency. The results are shown in FIG.

From FIG. 3, it can be seen that the sound absorbing member of the example shows higher sound absorbing characteristics than the comparative example, though the basis weight of the nonwoven fabric is smaller than that of the comparative example. Therefore, the sound absorbing member of the example has a lighter weight and higher sound absorbing characteristics than the comparative example. According to the sound absorbing member of the embodiment, since the nonwoven fabric 2 and the pillar 1 are formed of the same PP and are simply welded to each other, they do not include a different material such as an adhesive or a double-sided tape. Therefore, it is possible to collect and recycle the nonwoven fabric 2 and the pillar 1 integrally without separating them, and it is not necessary to remove the adhesive or the double-sided tape, so that the cost required for recycling can be significantly reduced. it can.

Also in manufacturing the sound-absorbing member of the embodiment, an adhesive and a double-sided tape are not required, so that material cost is reduced, and a step of attaching a PP nonwoven fabric via the adhesive or the double-sided tape is unnecessary. Therefore, the number of steps is also reduced. This results in an inexpensive sound absorbing member.

[0024]

According to the sound-absorbing member of the present invention, the sound-absorbing characteristic is equal to or better than that of the conventional sound-absorbing member, and the fiber assembly and the substrate can be collected and recycled without being separated. Therefore, the number of steps required for recycling is reduced, and the cost is reduced. Further, since an adhesive or a double-sided tape is not required, the material cost and the number of steps can be reduced, and the sound absorbing member can be inexpensive.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sound absorbing member according to an embodiment of the present invention and an enlarged explanatory view of a main part thereof.

FIG. 2 is a sectional view of a sound absorbing member of a comparative example.

FIG. 3 is a graph showing a sound absorption coefficient of sound of each frequency of the sound absorbing members of the example and the comparative example.

FIG. 4 is a sectional view of a conventional sound absorbing member.

[Explanation of symbols]

1: pillar (substrate) 2: PP nonwoven fabric (fiber aggregate) 20: welded portion 21: first PP
Fiber 22: second PP fiber (binder fiber) 3: anti-hair felt

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI G10K 11/16 G10K 11/16 D (72) Inventor Kuniyasu Ito Nagahata 1 Ogai-goai, Kasuga-cho, Nishikasugai-gun, Aichi Pref. ) Inventor Masamitsu Tsukahara 1 Ochiai Nagahata, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Inside Toyota Gosei Co., Ltd.

Claims (3)

[Claims] 1. A substrate made of a thermoplastic resin, and a fiber assembly laminated on the surface of the substrate and made of fibers of the same material as the substrate, wherein the fiber assembly and the substrate are at least partially A sound absorbing member characterized by being integrally welded and integrated. 2. The sound-absorbing member according to claim 1, wherein said fiber assembly is a non-woven fabric formed into a shape along the surface shape of said base material. 3. The sound absorbing member according to claim 2, wherein the nonwoven fabric contains 10 to 40% by weight of a binder fiber.