JP4361201B2 - Sound-absorbing material including meltblown nonwoven fabric - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound absorbing material made of a fiber assembly including a meltblown nonwoven fabric layer.
[0002]
[Prior art]
Conventionally, single-layer organic and inorganic fiber aggregates are often used as sound-absorbing materials contained in automobile engine rooms and home appliances. These fiber aggregates have the function of absorbing and attenuating the generated noise, but the effect is not always sufficient and is often unsatisfactory. In addition, there is a sound-absorbing material composed of two or more fiber aggregates having an ultrafine fiber layer with a very small apparent density as a surface layer, but there is a problem that the sound insulation performance on the surface is inferior.
[0003]
[Problems to be solved by the invention]
The present invention is intended to solve the above-described problems, and an object of the present invention is to provide a novel sound absorbing material that is excellent in heat resistance and remarkably excellent in sound absorbing performance such as noise.
[0004]
[Means for Solving the Problems]
As a result of various studies on the above problems, the present inventor has obtained a melt blown nonwoven fabric having a specific apparent density and a dense structure in which constituent fibers are integrated in a planar shape and other fiber aggregates, and a plane of the melt blown nonwoven fabric. It has been found that the sound absorption performance can be remarkably improved and the above problems can be solved by joining and integrating while maintaining the state, and the present invention has been completed.
[0005]
That is, the present invention comprises a base layer composed of a fiber assembly having an apparent density of 0.01 to 0.10 g / cm ³ and a basis weight of 50 to 2000 g / m ² , and a thermoplastic polymer having a melting point of 200 ° C. or higher. A melt blown nonwoven fabric having an apparent density of 0.1 to 0.4 g / cm ³ , a basis weight of 5 to 300 g / m ² , and a heat embossing area of 40% or less . A sound-absorbing material comprising a laminate, wherein a resin adhesive or a fused fiber is used at the joint between the base layer comprising the fiber assembly and the meltblown nonwoven fabric, and there is no entanglement or opening by needle punching The sound-absorbing material has a thickness of 5 to 50 mm, and a surface made of a melt-blown nonwoven fabric is used as a sound incident surface.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The melt-blown nonwoven fabric used for the sound-absorbing material of the present invention is made of a thermoplastic polymer having a melting point of 200 ° C. or higher, such as polyester, nylon, polyvinyl alcohol, polycarbonate, polyphenylene sulfide, etc. Is desirable. For example, in the field of sound-absorbing materials that are particularly required to have heat resistance such as automobile engine rooms, it is desirable to use polymers such as polybutylene terephthalate having excellent heat resistance and polymers such as polyphenylene sulfide.
In addition, it is important that the melt blown nonwoven fabric is composed of fibers having an average fiber diameter of 10 μm or less, and the constituent fibers are substantially accumulated in a planar shape after being laminated with the base layer. Although it is possible to obtain a nonwoven fabric having an average fiber diameter exceeding 10 μm by the melt blown method, a melt blown nonwoven fabric having an average fiber diameter exceeding 10 μm cannot achieve the object of the present invention. More preferably, it is desired to use a melt blown nonwoven fabric made of fibers having an average fiber diameter of 2 μm to 8 μm.
Furthermore, the basis weight of the melt blown nonwoven fabric used in the present invention needs to be 5 g / m ² or more, preferably 20 g / m ² or more. When the basis weight is less than 5 g / m ² , it is not possible to exhibit a sufficient sound absorbing effect when bonded and integrated with the fiber aggregate as the base layer. The upper limit of the basis weight is 300 g / m ² or less, preferably 100 g / m ² or less from the viewpoint of economy.
[0007]
Further, the apparent density of the meltblown nonwoven fabric, it is important that a 0.1 to 0.4 g / cm ^3, an apparent density of undesirable difficult to handle is less than 0.1 g / cm ^3, whereas the apparent density of 0. If it exceeds 4 g / cm ³ , the effect is reduced. Therefore, it is desirable to have an apparent density of preferably 0.15 to 0.35 g / cm ³ .
[0008]
Furthermore, in the sound-absorbing material of the present invention, the meltblown nonwoven fabric is accumulated in a planar shape on a collection surface such as an accumulation net in the nonwoven fabric production process, and the fibers are hardly arranged in the three-dimensional direction. Such a fiber web is heat-sealed by the fibers to form a sheet, but if it cannot be handled in the next joining step, it may be formed into a sheet by a method such as heat embossing or heat calendering. Although it is desirable not to perform hot embossing as much as possible, when embossing calendar is performed, the embossed area is preferably 40% or less, particularly preferably 10% or less. This is because the embossed portion is easily filmed, and such a filmed portion has a lower sound absorbing effect than the fiber portion.
[0009]
The base layer bonded and integrated with the meltblown nonwoven fabric is a fiber assembly having an apparent density of 0.01 to 0.10 g / cm ³ and a basis weight of 50 to 2000 g / m ² , and includes organic and inorganic natural fibers and A fiber assembly obtained by appropriately using synthetic fibers can be used.
If the apparent density is less than 0.01 g / cm ³ , the problem is that it is difficult to handle, and if it exceeds 0.10 g / cm ³ , the sound absorbing effect is inferior. Therefore, it is preferable that the apparent density is 0.02 to 0.08 g / cm ³ .
Further, if the basis weight is less than 50 g / m ² , the effect is difficult to obtain, and if it exceeds 2000 g / m ² , it is not economical. Accordingly, the basis weight is preferably 100 to 1500 g / cm ³ .
[0010]
This fiber assembly can be produced, for example, by a dry method such as a spunbond method or a card method, or a wet method using papermaking. The prepared fiber assembly is bonded by various means such as resin bonding by impregnation or spraying, heat melting bonding by fusing fibers, mechanical entanglement such as needle punch or water entanglement, and combinations thereof. It becomes the fiber assembly of the base layer.
[0011]
The base layer and the meltblown nonwoven fabric are preferably integrated by bonding. As a joining method, a resin adhesive such as hot melt or an adhesive net, a fused fiber, or the like is mainly used, but there is no particular limitation on the order of superposition or the number of layers in this case. If the melt blown nonwoven fabric is laminated and arranged so as to appear on at least one surface of the sound absorbing material, a plurality of melt blown nonwoven fabrics can be laminated within a range not exceeding the basis weight and the thickness of the sound absorbing material defined in the present invention. Similarly, the fiber assembly serving as the base layer is not limited to a single layer, and two or more layers can be laminated as necessary. These can be appropriately changed according to the required level of sound absorption performance, together with the basis weight of the melt blown nonwoven fabric.
It is preferable to avoid a mechanical entanglement means such as a needle punch if possible in the interlayer bonding between the melt blown nonwoven fabric and the base layer if possible. In such a means, a hole is formed in the dense melt-blown nonwoven fabric layer by the action of the needles penetrating each other. Further, the constituent fibers of the meltblown nonwoven fabric accumulated in a planar shape are rearranged three-dimensionally by the action of the above means. These two points both have a very bad influence on the sound absorption performance. Therefore, it is necessary to join the layers so as not to damage the two-dimensional fiber arrangement of the meltblown nonwoven fabric as much as possible.
[0012]
The overall thickness of the sound absorbing material of the present invention is 5 to 50 mm. If the thickness is less than 5 mm, a sufficient effect on the sound absorbing performance cannot be obtained, which is not preferable. On the other hand, when the thickness exceeds 50 mm, it is preferable in terms of sound absorbing performance, but when used as a sound absorbing material, the installation space becomes excessive, which is not desirable in product design. Furthermore, since it becomes difficult to handle in terms of processing such as cutting and molding, it is preferable and imparting excessive performance is also uneconomical.
[0013]
The sound absorbing material of the present invention obtained in this way is excellent in heat resistance and sound absorbing performance such as noise, and as a sound absorbing material included in an engine room of a vehicle such as an automobile or a home appliance, It can be used for building wall coverings, house wraps, etc.
[0014]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these at all.
[0015]
Example 1 and Comparative Example 1
A melt blown nonwoven fabric made of polybutylene terephthalate (melting point: 230 ° C.) is prepared, and heat embossed calendering is performed to obtain a nonwoven fabric having an average fiber diameter of 4.2 μm, an apparent density of 0.25 g / cm ³ , and a basis weight of 35 g / m ^2. It was. The embossed area by the dot-like pattern of the nonwoven fabric was 4.1%.
Next, 40% by mass of polyester fiber having a single fiber fineness of 13 dtex and 51 mm cut length, 45% by mass of polyester fiber having a single fiber fineness of 3.3 dtex and 40 mm cut length, and a softening point of about 170 ° C. using polyethylene terephthalate as a core component. A card web having a basis weight of 200 g / m ^{2 and} a punch felt having a basis weight of 245 g / m ² comprising 15% by mass of a polyester composite fiber having a single fiber fineness of 2.2 dtex and having a copolymer polyester as a sheath component were prepared.
Next, the above-mentioned card web having a basis weight of 200 g / m ² was passed through a dryer at 180 ° C. for heat-sealing. The apparent density was 0.017 g / cm ³ .
Subsequently, a polyamide melt-bonding net having a basis weight of 10 g / m ² is placed on the surface side of the nonwoven fabric, and the melt-blown nonwoven fabric is laminated thereon to form a laminate, which is fused and joined by passing between heating rolls. A sound-absorbing material (Example 1) having a basis weight of 245 g / m ² and a thickness of 13 mm was obtained. When the arrangement state of the fibers constituting the melt-blown nonwoven fabric of this sound absorbing material was enlarged and observed, it was confirmed that the fibers constituting the melt-blown nonwoven fabric were present in a substantially flat state.
[0016]
The sound absorbing performance of the sound absorbing material of the present invention and the punch felt only sound absorbing material having a weight per unit area of 245 g / m ² (Comparative Example 1, thickness 15 mm) was examined by the reverberation chamber method sound absorption coefficient measuring method of JIS A1409. However, it was found that the sound-absorbing material of the present invention is an excellent sound-absorbing material because it exhibits a sound-absorbing performance of about 30% or more in the region of 1000 Hz or more and about 50% or more at 3000 Hz.
[0017]
Example 2
Polyester composite fiber having a single fiber fineness of 13 dtex and a cut length of 51 mm of polyester fiber of 38% by mass, a single fiber fineness of 3.3 dtex and a cut length of 51 mm of polyvinyl alcohol fiber of 50% by mass, and the single fiber fineness of 2.2 dtex used in Example 1 A card web composed of 12% by mass was prepared, and the web was treated with hot air to obtain a felt having a thickness of 15 mm and a basis weight of 250 g / m ² .
On the other hand, a melt blown nonwoven fabric having an average fiber diameter of 3 μm, a basis weight of 50 g / m ² and an apparent density of 0.30 g / cm ³ was prepared. On this nonwoven fabric, an ethylene-vinyl acetate hot melt adhesive was applied at a rate of 30 g / m ² by a sintering method.
Next, the felt and the meltblown nonwoven fabric were laminated so that the hot melt adhesive application surface was in the middle, and both were adhered by a thermal calendar. The obtained laminate was 14 mm thick and had excellent sound absorbing performance similar to that of Example 1.
[0018]
【The invention's effect】
Unlike the conventional sound absorbing material, the sound absorbing material of the present invention includes at least one melt blown nonwoven fabric layer having a specific apparent density and basis weight as a surface layer, and therefore has excellent sound absorbing performance.

Claims (4)

It consists of a base layer made of a fiber assembly having an apparent density of 0.01 to 0.10 g / cm ³ and a basis weight of 50 to 2000 g / m ² , and a thermoplastic polymer having a melting point of 200 ° C. or higher, and has an average fiber diameter of 10 μm or less. A sound-absorbing material comprising a laminate of an apparent density of 0.1 to 0.4 g / cm ³ , a basis weight of 5 to 300 g / m ² , and a heat-embossed area having a heat embossing area of 40% or less. And a resin adhesive or a fusion fiber is used at a joint portion between the base layer composed of the fiber assembly and the meltblown nonwoven fabric, and there is no entanglement or opening by a needle punch, and the thickness of the sound absorbing material Is a sound-absorbing material characterized in that a surface made of melt-blown nonwoven fabric is used as a sound incident surface. A vehicle using the sound absorbing material according to claim 1. An electrical product using the sound absorbing material according to claim 1. A wall covering made of the sound absorbing material according to claim 1.