JP2001279567A - Sound-absorbing material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound-absorbing material which is lightweight and thin but has an excellent sound-absorbing property and an excellent vibration- damping characteristic. SOLUTION: This sound-absorbing material is characterized in that the fibers of a nonwoven fabric having a base weight of 30 to 200 g/m2 and containing superfine fibers having a fiber diameter of <=6 micron meter are interlaced with the fibers of a staple fiber nonwoven fabric having a METSUKE of 50 to 2,000 g/m2 and a fiber fineness of 7 to 40 micron meter to interlace the fabrics with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material having excellent sound absorbing properties and vibration damping characteristics despite its light weight and small thickness.

[0002]

2. Description of the Related Art Short-fiber nonwoven fabrics are widely used as sound-absorbing materials for automobiles and construction purposes. In order to enhance the sound absorption performance, methods such as reducing the fiber diameter to increase the air passage resistance and increasing the basis weight have been adopted. As a result, when high sound absorption performance is required, the fiber diameter is 1
Uses relatively thin fiber of about 5 microns, and has a basis weight of 500
Thick and heavy short-fiber nonwoven fabrics of up to 5000 g / m ² are used. Conventionally, non-woven fabrics containing ultra-fine fibers have been used for many applications because of their excellent properties such as excellent sound absorption properties, filter properties, and shielding properties, but they have problems such as low strength and poor form stability. For improvement, it has been used by laminating and compounding with another nonwoven fabric. At this time, as a method of laminating and integrating the nonwoven fabric, there are a method of applying a resin serving as a binder by spraying or transfer, and a method of using a heat fusion fiber. However, in these methods, it is necessary to perform heat treatment for the purpose of drying or melting and bonding the resin, which is not so preferable from the viewpoint of environmental pollution and energy saving. In addition, there is also a problem that the binder resin forms a film at the interface between the nonwoven fabrics and the sound absorbing property is reduced. On the other hand, a method of laminating and unifying a microfiber nonwoven fabric and a long-fiber nonwoven fabric is known by a name such as S / M / S. A meltblown nonwoven fabric which is a microfiber is laminated between spunbonded nonwoven fabrics and joined by a hot embossing method. There are known ways to do this. However, these nonwoven fabrics have a problem that they lack volume feeling and have a hard texture, which limits their use.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin and lightweight sound absorbing material which has high sound absorbing performance, is thin, and has good shape stability, at a low cost. In particular, in the field of automobiles, a lightweight and excellent sound absorbing material is demanded in order to improve fuel efficiency and comfort, and the purpose is to meet the demand.

[0004]

The present invention employs the following means to solve such a problem. The first invention has a weight per unit area of 30 to 50 μm or less containing ultrafine fibers having a fiber diameter of 6 μm or less.
And the nonwoven fabric 200 g / m ^2, is a sound absorbing material, characterized in that the fiber diameter is basis weight in 7-40 microns and a short fiber nonwoven fabric of 50 to 2000 g / m ² are integrated by entanglement of these fibers .

[0005] In a second aspect of the invention, the surface of the sound absorbing material of the first aspect has a fiber diameter of 5 to 20 microns and a basis weight of 50 to 250 g.
/ M ² short-fiber nonwoven fabric is bonded by a heat-fusible nonwoven fabric.

A third invention is a nonwoven fabric having a basis weight of 30 to 200 g / m ² containing ultrafine fibers having a fiber diameter of 6 μm or less, and a nonwoven fabric having a fiber diameter of 7 to 40 μm and a basis weight of 50 to 200 g / m ^2.
A method for producing a sound-absorbing material, wherein a nonwoven fabric of 0 g / m ^{2 and} a short fiber nonwoven fabric are integrated by either a fluid entanglement method or a needle punch method.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The composite nonwoven fabric of the present invention requires that at least two or more nonwoven fabrics be joined and integrated. Laminating a film or the like on a nonwoven fabric layer containing microfibers in order to control the air permeability and the like is also one of the desirable modes. In addition, it is preferable to form a composite with a woven fabric or a knitted fabric depending on the use. Further, a surface non-woven fabric having a design and a color or a pattern may be attached to the outside of the composite non-woven fabric, so that the composite non-woven fabric can be suitably used as a vehicle interior material or a soundproofing material for architectural use.

[0008] The ultrafine fiber-containing nonwoven fabric of the present invention preferably contains at least 10% by weight of ultrafine fibers having a fiber diameter of 6 microns or less. The entire nonwoven fabric may be composed of only ultrafine fibers, but if the content is too low, it is difficult to obtain the effect of the characteristics of ultrafine fibers. The fiber diameter of the ultrafine fibers is more preferably 5 microns or less, particularly preferably,
0.5-4 microns, most preferably 1.5-3
It is around a micron.

The method for producing the non-woven fabric containing ultrafine fibers is not particularly limited, but non-woven fabrics obtained by a melt-blowing method, in which fibers can be randomly arranged and production cost is low, are particularly preferred. Since the melt blown nonwoven fabric has low strength, it is preferable to use a nonwoven fabric bonded to a reinforcing nonwoven fabric such as a spunbonded nonwoven fabric, or to laminate three or more nonwoven fabrics simultaneously in the laminating step. At this time, it is preferable that the spunbonded nonwoven fabric having excellent abrasion resistance is placed on the surface layer side when used. Embossed laminated nonwoven fabric of meltblown nonwoven fabric and spunbonded nonwoven fabric is called S / M / S or S / M and is commercially available. It is also preferable to use these (S is spunbonded nonwoven fabric, M is meltblown nonwoven fabric). Represent).

It is also a preferable embodiment to use ultrafine fibers obtained by using split fibers or sea-island type fibers. As the split fiber, a split fiber may be used in advance, or splitting may be performed simultaneously at the time of lamination.

The ultrafine fiber-containing nonwoven fabric of the present invention preferably has a basis weight of 30 to 200 g / m ² . If the basis weight is less than 30 g / m ² , the effects of the ultrafine fibers such as shielding properties, filter performance, softness, and sound absorbing properties cannot be expected so much, which is not preferable. On the other hand, if the basis weight is more than 200 g / m ² , wrinkles may occur during the compounding with the short-fiber nonwoven fabric, or a problem that the bonding strength is weak may occur. Further, if the basis weight is too large, the intended effects of improving the shielding properties, filter performance, softness, sound absorbing properties, and the like do not change so much, which is not preferable in terms of cost reduction and weight reduction.

The material constituting the nonwoven fabric containing ultrafine fibers is not particularly limited, but polyester or polyolefin is particularly preferred from the viewpoint of recyclability.
Preferably, the same material as the short-fiber nonwoven fabric to be laminated is easily recycled and particularly preferable. On the other hand, there is no problem even if fibers composed of a plurality of materials are mixed.

Next, the nonwoven fabric composed of relatively thick fibers laminated with the ultrafine fiber-containing nonwoven fabric may be a long-fiber nonwoven fabric or a short-fiber nonwoven fabric. However, the short-fiber nonwoven fabric forms a loop by needle punching. It is easy to generate and is more preferable. The fiber diameter is preferably between 7 and 40 microns, particularly preferably between 7 and 20 microns. A fiber diameter smaller than 7 microns does not directly cause a serious problem. However, in the case of a short fiber non-woven fabric, it is not preferable in view of productivity such as spinning property from a card machine. If the fiber diameter is much smaller than 7 microns, the laminating effect according to the present invention will be reduced. Another problem may occur in that the nonwoven fabric is easily fluffed. When the fiber diameter is larger than 40 microns, the contribution to the sound absorbing performance is reduced, which is not preferable. When the nonwoven fabric composed of the thick fibers laminated with the ultrafine fiber-containing nonwoven fabric is a long-fiber nonwoven fabric, it is preferable that the fibers have a three-dimensional crimp to increase the peel strength of the laminate.

In the present invention, by laminating the above-mentioned non-woven fabric of relatively thick fibers with the non-woven fabric containing ultra-fine fibers, the non-woven fabric containing ultra-fine fibers is low in shape stability (easy to be fragile and easy to fluff), thereby maintaining bulkiness. It is possible to improve the problem that a problem easily occurs, and to exhibit high cushioning property and vibration damping property. In general, it is considered that the larger the thickness of the sound absorbing material, the higher the performance can be obtained, and the effect of laminating the sound absorbing material is great for the purpose of controlling the thickness.

[0015] The basis weight of the relatively thick fiber non-woven fabric is as follows.
It is a non-woven fabric of 50 to 2000 g / m ^2. Weight is 50g
If it is smaller than / m ² , the laminating effect is small and the nonwoven fabric is not preferred in terms of bulkiness and soft texture. On the other hand, 20
If the basis weight is larger than 00 g / m ² , the thickness becomes too large to take up space and the weight increases, which is not preferable.

When the relatively thick fiber non-woven fabric is a short fiber non-woven fabric, the length of the short fibers is preferably 38 to 150 mm, particularly preferably 50 to 100 mm. When a composite nonwoven fabric is used as a sound absorbing material, the longer the fiber length, the better the sound absorption coefficient is. However, if the fiber length is too long, the spinning property from the card deteriorates, which is not preferable. The short fiber may be a single component, or may be a mixture of two or more types or a multicomponent fiber. If the weight fraction is about 30% or less in order to adjust the hardness of the nonwoven fabric, the characteristics will not change much even if thicker fibers are mixed. If there are too many thick fibers, problems such as the texture of the nonwoven fabric becoming too hard tend to occur, which is not so preferable. It is also preferable to use heat fusible fibers having different melting points from the viewpoint of improving dimensional stability.

The packing density on a weight basis of the short fiber nonwoven fabric is as follows:
It is preferably from 0.005 to 0.3 g / cm ³ from the viewpoint of bulkiness. If the packing density is too low, the morphological stability deteriorates, which is not preferred. 0.3g / c packing density
If it is larger than m ³ , the bulkiness is poor and it is difficult to satisfy the object of the present invention.

In the method of laminating and integrating the nonwoven fabric according to the present invention, the nonwoven fabric is integrated by either a fluid entanglement method or a needle punch method. Needle punch method can be adopted a method that is generally implemented as a nonwoven fabric processing method, for example,
This is a method described in "Foundations and applications of nonwoven fabrics" edited by the Japan Society of Textile Machinery Nonwovens Study Group. When the meltblown nonwoven fabric and the short-fiber nonwoven fabric are combined using the needle punch method, it is generally expected that holes will be formed in the meltblown ultrafine fiber nonwoven fabric, and that sound absorption performance and filter performance will be reduced. However, surprisingly, the present invention does not exhibit such disadvantages.

When performing the needle punching process, it is preferable to use a needle (needle) thinner than 38 count, particularly preferably 40 to 42 count. It is preferable that the needle enters from the short fiber nonwoven fabric side and causes a short fiber loop to be generated outside the ultrafine fiber-containing nonwoven fabric. The ultrafine fiber-containing nonwoven fabric is easily fuzzed because the fiber is caught by other objects or cut by it, but the short fiber loop prevents the superficial fiber-containing nonwoven fabric from fuzzing,
As a cushion layer, the external force applied to the microfiber-containing nonwoven fabric layer is reduced, which is effective in preventing breakage.

Further, when laminating with another nonwoven fabric or film, the melt blown nonwoven fabric is broken when an external force such as bending or pulling is applied by bonding the short fiber loop and the third material to be laminated. Can be prevented from being performed. In order to form an appropriate loop size, the needle depth of the needle punch is preferably 15 mm or less. If the needle depth exceeds 15 mm, the nonwoven fabric breaks due to the impact when the needle and the short fiber penetrate the ultrafine fiber nonwoven fabric, and the needle hole after penetrating becomes too large, which is not preferable. The needle depth depends on the barb position of the needle, but is preferably 5 mm or more in order to increase the entanglement of the nonwoven fabric and prevent peeling.

The puncture density is preferably 30 to ²⁰⁰ holes / cm ² . If the puncture density is less than 30 holes / cm ² , the problem of peeling of the nonwoven fabric is likely to occur, and 250 holes / cm ²
If it is larger, the total opening area due to the piercing hole is too large, or the melt-blown ultrafine fiber nonwoven fabric is easily broken or broken, which is not preferable.

The nonwoven fabric, which is particularly suitable as a mating member to be laminated on the sound-absorbing material of the first invention, for preventing fluff and improving form stability of the sound-absorbing material, has a fiber diameter of 5 to 20 microns and a basis weight of 50 to 50. It is a short fiber nonwoven fabric of 250 g / m ² . When the fiber diameter of the short fiber non-woven fabric is less than 5 microns, the effect of improving the form stability and the like is small, which is not preferable. 2
Above 0 microns, non-uniform spots on the nonwoven fabric are noticeable and not very desirable. With respect to the basis weight, if it exceeds 50 g / m ² , the unevenness of the formation is unnoticeable, and if it exceeds 250 g / m ² , it is not preferable because it does not conform to the purpose of the present invention for the purpose of weight reduction. It is preferable that the surface of the nonwoven fabric to be laminated is colored or printed with a pattern to impart design. This makes it possible to visually harmonize with the surroundings as a sound-absorbing material for a building structure or an automobile interior material.

As a method for bonding the short-fiber nonwoven fabric, it is preferable to use a heat-fusible nonwoven fabric. Adhesion with a heat-adhesive film or the like may result in loss of air permeability and reduced sound absorption performance. When the film is thin, there is not much problem. However, when the film is thicker than about 30 μm, the sound flow may be reduced because the flow of air is blocked and sound waves are reflected on the surface. Further, the adhesive strength is higher when the heat-adhesive nonwoven fabric is used, and peeling off at the interface is less likely to occur.

[0024]

The present invention will be described below with reference to examples. The evaluation method was as follows. (Average fiber diameter): A scanning electron micrograph was taken at an appropriate magnification, 20 or more fiber sides were measured, and the average value was measured. When the microfiber nonwoven fabric is melt blown,
Due to large variations in fiber diameter, 100 or more fibers were measured and the average value was adopted.

(Fabric weight and packing density): Non-woven fabric 20c
It was cut out into m-squares and the measured weight was converted to about 1 m ² to obtain the basis weight. Packing density is 2
A value obtained by dividing the thickness under a load of 0 g / cm ² by g
/ Cm ³ as a unit.

(Peeling): The operation of bending the composite nonwoven fabric back and forth by 90 degrees by hand was repeated 20 times, and it was visually evaluated whether peeling occurred.

(Sound absorption coefficient): The sound absorption coefficient by the normal incidence method was determined according to JIS A-1405. 1000 as representative value
The average value of Hz and 2000 Hz was used.

Example 1 An average fiber diameter of 14 μm was formed on a polypropylene melt-blown nonwoven fabric having an average fiber diameter of 3 μm and a basis weight of 100 g / m ^2.
Micron, fiber length 51 mm, crimp count: 12 g / m ² , short fiber having a basis weight of 250 g / m ² , packing density: 0.06 g /
A needle-punched nonwoven fabric made of polyethylene terephthalate of cm ³ was overlaid, and a needle-punch lamination process was performed using a 40th needle at a puncture density of 50 needles / cm ² and a needle depth of 10 mm. Even if the sound absorbing material was bent about 20 times, the problem of peeling did not occur, and the sound absorbing coefficient was as high as 68%, which was good.

Example 2 A sound absorbing material was prepared under the same conditions as in Example 1 except that the short fiber had a fiber length of 38 mm. The sound absorption coefficient was 60%, which was inferior to that of Example 1, but showed good performance.

Example 3 A polyethylene terephthalate melt-blown nonwoven fabric having an average fiber diameter of 3 μm and a basis weight of 100 g / m ² was overlaid on a polyethylene terephthalate spunbonded nonwoven fabric having an average fiber diameter of 14 μm and a basis weight of 20 g / m ^2. An average fiber diameter of 14 micron, a fiber length of 51 mm, and a crimping number of 12 pieces / inch.
A needle-punched nonwoven fabric made of polyethylene terephthalate having an m ² of 0.06 g / cm ³ and a packing density of 0.06 g / cm ³ is superimposed, and a puncture density of 50 needles / cm ² and a needle depth of 1 are obtained using a 40th needle.
Needle punch lamination processing was performed at 0 mm. Even if the created nonwoven fabric is bent about 20 times, the problem of peeling does not occur,
The sound absorption coefficient was as high as 71%, which was good.

Example 4 The sound absorbing material prepared in Example 1 had a fiber diameter of 12 μm.
8 grey-colored short fibers with a basis weight of 150 g / m ²
0%, 20 low-melting-point heat-fusible fibers of the same fiber diameter and the same color
% Mixed non-woven fabric by heat treatment
Adhesion was performed at 140 ° C. with a heat-fusible long-fiber nonwoven fabric (Dynac, manufactured by Kureha Tech Co., Ltd.) of 5 g / m ² . Even if the produced nonwoven fabric was folded about 20 times, no problem of peeling occurred, and the sound absorption coefficient was as high as 74%, which was good. In addition, the appearance of the nonwoven fabric was extremely good, and it was at a level suitable for use in interior materials of automobiles without any problem of fluff.

Comparative Example 1 The two types of nonwoven fabrics used in Example 1 were combined with each other by applying an acrylic resin binder at 15 g / m ² . Even if the composite nonwoven fabric was bent, the problem of initial peeling did not occur, but repeated peeling caused partial peeling. It is considered that the adhesiveness of the melt blown nonwoven fabric constituent fibers was weak, and the inside was broken. The sound absorption coefficient was as high as 70%, which was as good as that of Example 1. Although the sound absorption coefficient is slightly higher than that in Example 1, there is also the effect of the adhesion of the resin, and there is no difference due to the trace of the puncture hole by the needle punch, and it is considered that the sound absorption coefficient is about a measurement error.

Comparative Example 2 ^On a polypropylene melt-blown nonwoven fabric having an average fiber diameter of 3 μm and a basis weight of 15 g / m ² , a basis weight of 250 g of short fibers having an average fiber diameter of 14 μm, a fiber length of 51 mm and a number of crimps of 12 / inch was prepared. / M ² , packing density 0.06 g / c
A needle-punched nonwoven fabric made of polyethylene terephthalate of m ³ was stacked, and needle-punch lamination was performed using a 32nd needle at a puncture density of 50 needles / cm ² and a needle depth of 18 mm. Meltblown nonwoven of about 5 to 20 per layered nonwoven fabric 1 m ² was broken has occurred a problem with the needle hole near. Although the problem of peeling did not occur even when the composite nonwoven fabric was bent, the number of torn spots increased, which was a problem. The sound absorption coefficient was measured at the place where there was no breakage.
It was a low problem.

Comparative Example 3 A short fiber made of polyethylene terephthalate having an average fiber diameter of 14 μm, a fiber length of 51 mm, and a crimp count of 12 / inch and having a basis weight of 500 g / m ² was prepared by using a 40th needle. Puncture density of 30 holes / c from both sides
Needle punching was performed at m ² and a needle depth of 10 mm to obtain a nonwoven fabric having a packing density of 0.05 g / cm ³ . The nonwoven fabric is
Although the basis weight was higher than that of Example 1, when the sound absorption coefficient was measured, it was as low as 21%, which was a problem.

[0035]

The sound-absorbing material of the present invention can be provided at a low cost as a thin and lightweight sound-absorbing material having high sound absorbing performance, good shape stability and low weight. In particular, it can be used as a lightweight and excellent sound absorbing material for improving fuel efficiency and comfort in automobiles. It is suitably used as a sound absorbing material in a wide range of other industrial applications.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G10K 11/162 G10K 11/16 A

Claims (3)

[Claims] 1. A nonwoven fabric having a basis weight of 30 to 200 g / m ² containing ultrafine fibers having a fiber diameter of 6 μm or less, and a short fiber nonwoven fabric having a basis weight of 7 to 40 μm and a basis weight of 50 to 2000 g / m ^2. Characterized by being integrated by entanglement of these fibers. ^2. A short-fiber nonwoven fabric having a fiber diameter of 5 to 20 microns and a basis weight of 50 to 250 g / m ² is adhered to the surface of the sound absorbing material according to claim 1 by a heat-fusible nonwoven fabric. A sound absorbing material characterized by the following. 3. A non-woven fabric having a basis weight of 30 to 200 g / m ² containing ultrafine fibers having a fiber diameter of 6 μm or less, and a short fiber non-woven fabric having a basis weight of 7 to 40 μm and a basis weight of 50 to 2000 g / m ^2. A sound absorbing material, which is integrated by either a fluid entanglement method or a needle punch method.