KR20050123137A - Acoustically effective nonwoven material for vehicle liners - Google Patents

Abstract

An acoustically effective nonwoven for linings of motor vehicles comprises a porous fibrous skeleton made of coarse fibers (8). These coarse fibers (8) comprise in particular staple fibers or spun-bonded fibers. A continuously changing weight quota of melted-on microfibrous material (7) is foreseen in a front and/or rear surface region (4). This melted-on microfibrous material (7) clings to the coarse fibers (8) and bonds these in such a manner that the nonwoven has a predetermined airflow resistance and is stiffened at least in its surface region (4). The airflow resistance in the surface region (4) has a value of between 200 - 60000 Nsm-3, in particular between 800 - 35000 Nsm-3, preferably between 1000 - 20000 Nsm-3, and mainly about 1400 Nsm-3. The bending stiffness of this fibrous nonwoven has a value of between 0.005 and 10 Nm, and in particular a value of between 0.25 and 6.0 Nm.

Description

ACOUSTICALLY EFFECTIVE NONWOVEN MATERIAL FOR VEHICLE LINERS}

The present invention relates to an acoustically effective nonwoven material according to the end of claim 1.

Nonwovens are increasingly used in the automotive industry because of their favorable acoustic properties. In particular, there is a desire in the automotive industry to use liners that have a variety of acoustic properties, depending on the use, and are lightweight, relatively thin, easily molded but stable and easily recycled. Thus, it is desirable to benefit from liners that meet many technical functions while minimizing the cost for expensive materials.

Known liner parts are disclosed in US-2001 / 0036788 or EP-0,939,007, all of which have a composite structure by a number of separate layers, each of which separate layers fulfill different technical functions. .

The production of composite structures has proved to be a disadvantage because these different layers of material have to be prepared in advance and attached to one another. In addition, these composite structures tend to delaminate over time. The effort required to suppress such delamination using adhesive foils and / or dots is relatively large and makes the manufacturing process more costly.

It is therefore an object of the present invention to provide an acoustically effective nonwoven for automotive linings without the disadvantages of known parts. In particular, it is an object of the present invention to provide a porous nonwoven fabric that can be improved and can easily control sound absorption and morphological stability. At the same time, the nonwovens of the present invention should be lightweight, thin, durable and easily recycled.

This object is achieved by providing a nonwoven fabric having the features of claim 1, in particular, consisting of a fibrous skeleton having a certain airflow resistance and form stability, comprising support fibers or coarse fibers, wherein microfibers are introduced into the skeleton and a part thereof It is achieved by the present invention by providing an acoustically effective nonwoven that melts completely into the backbone. This configuration makes it possible for the nonwoven fabric to be strengthened at one half of the thickness, preferably one third of the thickness, in the surface area thereof and have a certain airflow resistance. Thus, the required different technical functions of the nonwoven of the present invention are achieved by introducing the same or different types of microfibers into the surface area of a given fiber backbone. Thus, the liner of the present invention does not include individual layers but has a continuously varying weight quarter of fiber material.

The present invention utilizes known manufacturing processes as described, for example, in DE-100,44,694. This publication discloses a method of making a nonwoven as used to make soft and tensile clean towels. This manufacturing method couples the spunbonded fiber layer to the meltblown fiber layer by a hydro-entanglement process.

In addition, EP-0,418,493 is a two-layer nonwoven fabric used as a panty liner or disposable diaper where each layer is bonded to each other, applying a fine jet of water to a particular layer, from which fibers are directed from this direct heat layer. A two-layer nonwoven fabric is disclosed in which each layer is bonded to each other by forming a wear resistant bond between the two layers in a manner that allows partial transport to another layer.

Nonwoven fibers made in this way are generally used for products in the field of personal or household hygiene, and are typically not particularly suitable for use as safety parts, ie ceilings for supporting automotive liners, or as sound-efficient automotive parts. In particular, in these known nonwovens the fine fibers are evenly distributed throughout the whole fiber backbone (wet wipes) or are only twisted together at the mutual surface of separate layers (clean towels).

In contrast and according to the invention, all the microfibers are completely shifted to the surface area, ie less than half the thickness of the fiber skeleton consisting of the coarse fibers. The depth of this surface area is determined by the penetration depth of the microfibers and is defined herein below as the statistical average penetration depth. Statistically, the weight quarter of the microfiber material in the surface area continuously changes, ie, decreases constantly with depth.

Thus, the preparation of the nonwovens described above has a microfiber (ie 0.01 to 1.0 dtex, preferably 0.1 to 0.6 dtex) on top of the nonwoven made of skeletal fibers (ie, fibers having a titer greater than 1 dtex). By positioning a nonwoven fabric). This fiber material is selected such that the melting temperature of the skeletal fibers is higher than the melting temperature of the microfibers. Subsequently, many microjets of water are directed onto the microfibers under high pressure causing the fibers of the microfiber nonwovens to twist around the coarse fibers of the fiber backbone. After the subsequent drying step, the microfiber reinforced nonwoven is treated to a specific temperature by a hot gas stream directed to a heat source, for example a nonwoven, at which temperature the fibers of the microfiber nonwoven are at least surface-preferably Is fully-melted and after this heat treatment, the skeletal fibers are bonded and strengthened in the surface area of the nonwoven fabric.

The manufacturing method may be modified such that the microfibers are melted by radiant heat from other heat sources, such as microwave ovens, by contact heat, or by hot steam or other fluids. The temperature and holding time of the heat source on the nonwoven fabric can be determined in advance by those skilled in the art.

The product produced by the process of the present invention is thus characterized by a fibrous backbone comprising a weight quarter melt-on microfiber material in which the front and / or rear regions vary continuously. The skeletal fibers, hereinafter referred to herein as coarse fibers, have a fineness of more than 1 dtex, preferably 6 to 17 dtex. Suitable skeletal fibers are staple fibers as well as infinite spunbonded fibers. These may be made of suitable polymers or may comprise inorganic fibers, in particular glass fibers, metal fibers or natural fibers. In advantageous embodiments, such fiber backbones have an area weight of about 20 to 150 g / m ² . The area weight can be predetermined by a person skilled in the art according to the requirements, and can also have an area weight of about 800 g / m ² . Coarse fibers made of PET are used in preferred embodiments of this fibrous backbone.

The claimed nonwoven fabric is reinforced in its surface area by applying a melt-on microfiber material, in particular a meltblown fiber material, having a diameter of 2 to 8 μm and a fiber length of 2 to 80 mm. Depending on the length of the fiber, it has been found advantageous to shorten the microfibers prior to delivery of the microfibers into the fiber backbone (possibly by hydroentangled method). The materials of these melt-on microfibers are mainly present at the junctions of the coarse fibers or must be deposited on the respective coarse fiber filaments. According to the invention, such deposits must be present in the surface area of the nonwoven in statistically continuously varying weight quarters and in quarters that decrease in depth direction. In a preferred embodiment described, the total area weight of this melt-on microfiber material is about 5-50 g / m ² (about 10-30% of the area weight of the fibrous backbone) and this material is Co-PET. The surface area reinforced with the melt-on microfiber material (about 5 to 35%, up to 50% of the total thickness of the claimed nonwoven) is still porous and substantially determines the airflow resistance of the entire nonwoven. The nonwoven fabric according to the invention has an air flow of 200 Nsm ⁻³ <R _t <60,000 Nsm ⁻³ , in particular 800 to 35,000 Nsm ⁻³ , preferably 1,000 to 20,000 Nsm ⁻³ , mainly about 1,400 Nsm ⁻³ after the molding press step It is formed in such a way as to have a resistance.

In addition, the deposition of the microfiber material on the coarse fibers substantially strengthens the fiber backbone in the surface region of the fiber backbone in a manner that allows the nonwovens of the present invention to self-support. In particular, by means of nonwoven fabrics having skeletal fibers of more than 1 dtex, referred to herein as coarse fibers, and by using the hydroentangled method described above in conjunction with the melting process, particularly enhanced stability and form strength can be achieved because On the one hand, the simple twisting of the coarse fibers leads to specific reinforcement in the surface area, on the other hand the drop-like melt-on microfiber material adheres to the coarse fibers and thereby reinforces them when solidified, in particular the junction point. Because it strengthens. The combination of these two reinforcing mechanisms induces the required bending stiffness of the nonwovens of the present invention and produces certain form reinforced and self supporting nonwovens that can be used in the automotive industry.

The above mentioned elasticity and resilience of the coarse fibers in the interior of the nonwovens with the continuously varying stiffness in the surface area create a high acoustically effective part. This part acts like an acoustic spring-mass-system where the mass is substantially replaced by porous enhancement in the surface area. By such an acoustic system, the unavoidable initiation of the resonance characteristics of conventional spring-mass-systems can be offset or avoided.

However, it should be understood that the specific design of the nonwovens of the present invention depends on their intended use. Accordingly, the front surface of the nonwoven fabric of the present invention may be open pores, while the back surface of the same nonwoven fabric may be air impermeable.

It may be possible to use microfiber nonwoven fabrics made of meltblown fibers having varying degrees of fineness and having different melting points or combinations thereof. In addition, it is possible to control the penetration depth of one or another type of microfiber by adjusting the impact of the water microjet moving the microfibers by adjusting the pressure and the holding time. In this way, after the heat treatment, a nonwoven fabric having a viscous nonwoven surface comprising partial melt-on microfibers can be provided, which configuration allows another standard nonwoven fabric or nonwoven fabric of the invention to adhere to the microfibers. . It should be understood that the use of suitable mixtures of microfibers facilitates the adjustment of airflow resistance to the surface area.

The advantages of the present invention are readily apparent to those skilled in the art. In particular, the combination of known manufacturing methods used in other fields can produce nonwoven fabrics suitable for automotive linings that have the desired airflow resistance and the required bonding stiffness but do not have a separate layer. The possibility of obtaining a nonwoven fabric suitable for use as an automotive liner and having an area integrated into a surface area that produces a strong surface area and a desired airflow resistance is surprising. Nonwoven fabrics made in accordance with the present invention can be designed in such a way that they are extremely thin, lightweight, and easily adjusted and have a certain stiffness and selectable acoustic efficiency. It has been demonstrated that the nonwovens of the present invention have the particular advantage that they may not peel off even after prolonged and intensive use. Elimination of the risk of delamination also increases the durability of the nonwovens of the present invention. In addition, the nonwovens of the present invention can be made from only one type of material and still have all the properties required for automotive liners in the modern world. Thus, the nonwovens of the present invention are made from single-material parts, allowing such parts to be discarded or reused at low cost.

For clarity, there will be no distinction between endless filaments or fibers having a particular length, and the term "fiber" includes both. For those skilled in the art, the term "microfiber" means a meltblown fiber which typically has a titer of 0.01 to 1.0 dtex, preferably of 0.1 to 0.6 dtex and typically of 0.2 dtex. Coarse fibers described herein have a titer greater than 1.0 dtex and / or natural fibers such as sisal, coir, hemp, bark or glass fibers, metal fibers or Inorganic fibers.

Advantageous embodiments of the nonwoven according to the invention have the features of the appended claims.

Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments and drawings.

1 is a schematic diagram of a method for producing a nonwoven fabric of the present invention.

FIG. 2 is an enlarged view of the region A in FIG. 1.

3A-3D are schematic diagrams of the physical properties of the nonwovens of the present invention.

4 is a schematic enlarged cross-sectional view of a nonwoven fabric of the present invention.

5 is a schematic view of a method for producing a nonwoven fabric of the present invention further developed.

In order to produce the nonwoven fabric 1 according to the invention and as schematically shown in FIG. 1, the coarse fibrous nonwoven fabric 2 is covered with a microfiber layer. This coarse nonwoven fabric 2 preferably comprises spunbonded fibers made of PET and having a titer of greater than 1.0 dtex. These coarse fibrous nonwovens act as fibrous frameworks, have the soft spring properties of acoustic spring-mass-systems and have good resilience. This fiber backbone has an area weight of 20 to 800 g / m ² and is preferably made of PET material. It should be understood that such frameworks may include natural fibers, glass fibers, metal fibers or inorganic fibers. In this embodiment, the covered nonwoven is treated in a so-called hydroentanglement process in which the microfiber layer 3 lying in this process is transferred into the surface area 4 by the water microjet 5. As used herein, the term "surface area" defines an area of nonwoven that includes microfiber material and spans 1/3 to 1/2 of the total nonwoven thickness. During this process, the microfibers slide along the skeletal fibers and wind themselves around the skeletal fibers, or are preferably twisted around the junctions of the fibrous frameworks. These microfibers have a titer of 0.01 to 1.0 dtex, preferably a titer of 0.1 to 0.6 dtex, typically of 0.2 dtex, and are preferably made of PET or Co-PET. This method controls the penetration depth of the microfibers and allows the weight quarter of the introduced microfibers to be selectively and continuously distributed throughout the surface area of the fiber skeleton, in particular in a continuously varyable manner; This configuration means that the gradient of the weight quarter of the introduced microfiber material can be selectively adjusted. The fiber skeleton 2 treated in this way is subsequently subjected to a drying and heating process, in particular in which the microfibers introduced into the surface region 4 of the fiber skeleton 2 are subjected to hot air or any other heating device 6. Conveyed through a processing station that is melted by After passing through this processing station, the shape of the microfibers 3 changes into a droplet, and these droplets bind the coarse fibers together in the region of the junction or intersection point to strengthen the fiber skeleton in these regions. In this way porous and form resistant nonwovens are produced, and acoustically effective and self-supporting form parts can be produced which can be used in the automotive industry of the modern world. It is to be understood that the acoustic properties and stiffness of the nonwoven can be selectively affected by changes and distribution of the fiber material, and / or the fineness of the fiber and / or the quarter of the selected fiber.

The area A of FIG. 1 is shown in FIG. This figure demonstrates how a drop-like melt-on microfiber material 7 is deposited on the coarse fibers 8 of the fiber backbone 2 to strengthen the nonwoven in the surface region 4.

3A shows the correlation between the different properties of the nonwoven fabric 1 of the present invention. The nonwoven fabric 1 shown schematically has three regions: microporous surface region 4; A springable core region 19; And air impermeable substrate region 10. The substrate region 10 and the surface region 4 are produced in a similar manner, but their melt-on microfiber materials may have different weight quarters and different penetration depths.

3B shows an exemplary curve of airflow resistance R _t value according to the depth d of the nonwoven of the present invention. The characteristic values for the airflow resistance in the surface region 4 are 500 to 5000 Nsm ⁻³ , these values in the core region 19 are about 200 Nsm ⁻³ and in the substrate region 10 200 to 10,000 Nsm ^−3. Or more.

The curve shown in FIG. 3C illustratively illustrates the dependence of the bending stiffness B on the depth d. This bending stiffness is substantially dependent on the weight quarter of the melt-on microfiber material and the density of the fiber in the surface area. In this example, the gradient is smaller in the microporous surface region 4 than the gradient in the air impermeable substrate region 10. In the nonwoven fabric of the present invention, the value for bending stiffness can vary from 0.005 to 10.5 Nm; In particular, these values are 0.025-6.0 Nm.

3D shows the density quarter K of different fibers and melt-on fiber materials. Curve a shows representative density values for spunbonded or coarse fibers, which fibers are present at greater density in the surface area because of the hydroentangled process. Curve b shows an exemplary density distribution of the melt-on microfiber material, demonstrating that its weight quarter has a process of continuously changing. The gradient of this fiber material depends on the holding time and hydraulic pressure of the hydroentanglement process. The ratio of coarse to microfibers is in the range of 3: 1. Curve c shows the quarter of the meltblown fibers that are introduced into the surface area of the nonwoven but do not melt. By such a melt blown fiber, it is possible to specifically adjust the airflow resistance. These non-melt-on microfibers are in particular meltblown fibers having a titer of 0.01 to 1.0 dtex, in particular polyester, copolyester, polyamide, polypropylene or similar synthetic materials, preferably PET or Co- It is made of PET.

4 is a schematic view of the nonwoven fabric of the present invention observed under a microscope. This figure clearly illustrates how the porous fiber backbone made of the coarse fibers 8 is filled with the melt-on microfiber material 7 and the non-melt-on microfiber material 9. The weight quarter of the melt-on fibers present just below the surface is significantly higher inside the surface area 4. The distribution of non-melt-on microfibers in this region is clearly shown. Formation of the microporous reinforcement layer in the surface region of the fiber skeleton is essential in the nonwoven fabric of the present invention.

It is to be understood that the nonwoven fabric 1 of the present invention may be combined with other nonwoven fabrics of the same kind to obtain parts having application specific properties. Such a manufacturing method is schematically illustrated in FIG. 5. Differently designed nonwoven fabrics 11, 12 in this process are treated with known hydroentanglement processes (station 13) to obtain different intermediate products 14, 15, 16, 17, and the intermediate products are mutually compatible in a suitable manner. It is loaded on top of the liver and joined together by a known heat treatment process 18.

It will be apparent to those skilled in the art that the nonwoven fabric of the present invention may be provided with an air permeable decorative layer, air and / or water impermeable foil. In the case of decorative layers, woven layers, knits, wovens, decorative nonwovens and / or foam layers are particularly suitable.

Claims (12)

Acoustic effective nonwoven fabric 1 for automobile lining comprising a porous fibrous skeleton 2 made of coarse fibers 8, in particular a nonwoven fabric comprising staple fibers or spunbonded fibers, the fibrous skeleton 2 being front And / or melt in a manner such that the nonwoven fabric 1 has a predetermined airflow resistance, with a continuously varying weight quarter of the melted on microfiber material 7 in the back region 4, 10. A motor vehicle characterized in that the on-microfiber material 7 is reinforced at least in the surface areas 4, 10 by a predetermined bending stiffness in such a way that the microfiber material 7 adheres to and binds to the coarse fibers 8 and causes the nonwoven to self-support. Acoustic effective nonwoven fabric for lining (1). 2. The nonwoven fabric according to claim 1, wherein the coarse fibers (8) have a titer above 1 dtex, in particular a titer in the range of 1 to 35 dtex, preferably 6 to 17 dtex. The nonwoven fabric according to claim 1 or 2, wherein the coarse fibers (8) are spunbonded fibers, in particular made of polyester, polypropylene or polyamide, preferably made of PET. 4. The nonwoven fabric according to any one of claims 1 to 3, wherein the nonwoven fabric (1) comprises non-melt-on microfibers (9). 5. The non-melt-on microfiber 9 according to claim 4, characterized in that the non-melt-on microfiber 9 has a titer in the range of 0.01 to 1.0 dtex, preferably a titer of 0.1 to 0.6 dtex, typically about 0.2 dtex. Non-woven. 6. The microfiber material 7 according to claim 1, wherein the microfiber material 7 is a meltblown fiber material, in particular polyester, co-polyester, polyamide, co-polyamide, polypropylene, co-poly Non-woven fabric, characterized in that it is made of propylene or similar components, preferably made of PET or Co-PET. The nonwoven fabric as claimed in claim 1, wherein the coarse fibers have a higher melting point than the microfiber material. The airflow resistance in the surface region of the fibrous nonwoven fabric 1 is 200 to 60,000 Nsm- ³ , in particular 800 to 35,000 Nsm- ³ , preferably 1,000 to 20,000 Nsm. A nonwoven fabric characterized by a value of ^-3 and predominantly about 1,400 Nsm ^-3 . 9. A nonwoven fabric according to any one of the preceding claims, characterized in that the fibrous nonwoven fabric (1) has a bending stiffness (B) of 0.005 to 10 Nm, in particular a value of 0.025 to 6.0 Nm. . 10. The nonwoven fabric of any of claims 1-9, wherein the nonwoven fabric is combined with one or more additional nonwoven fabrics. 11. The nonwoven fabric of any of claims 1 to 10, wherein the nonwoven fabric is provided with an air impermeable layer. The nonwoven fabric of claim 1, wherein the nonwoven fabric is provided with a decorative layer.