CN112810268A

CN112810268A - Sound-absorbing textile composite material

Info

Publication number: CN112810268A
Application number: CN201911118425.1A
Authority: CN
Inventors: 张伟; A·魏克
Original assignee: Freudenberg SAS
Current assignee: Freudenberg SAS
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2021-05-18
Anticipated expiration: 2039-11-15
Also published as: CN112810268B

Abstract

The invention relates to a flow resistance of 250Ns/m³To 5000Ns/m³In particular a composite nonwoven fabric, comprising: a) first of allAn apertured carrier layer comprising as skeleton fibers thick staple fibers having a denier of 3 to 17dtex and thin staple fibers having a denier of 0.3 to 2.9 dtex; b) a microporous flow layer disposed on the first apertured support layer, said flow layer comprising microfibers having fiber diameters less than 10 micrometers; c) a second apertured carrier layer comprising as skeleton fibres coarse staple fibres having a titre of 3 to 17dtex and fine staple fibres having a titre of 0.3 to 2.9dtex, wherein the second apertured carrier layer is arranged on the side of the microporous flow layer facing away from the first apertured carrier layer; and d) an additional microporous flow layer comprising microfine fibers having a diameter of less than 10 microns, wherein the additional microporous flow layer is arranged on the side of the second apertured carrier layer facing away from the additional microporous flow layer.

Description

Sound-absorbing textile composite material

Technical Field

The application relates to a sound absorbing textile composite. The application also relates to a method for producing said textile composite material and to the use thereof as a sound absorber in the automotive field.

Background

In US5298694 a method for sound absorption is described, wherein a sound-insulating nonwoven fabric is used, which comprises an ultrafine fibrous component (meltblown ultrafine fibers) mixed with a crimped fill fibrous component (crimped bulking fibers). The microfine fibers have an average fiber diameter of less than 15 microns, preferably in the range of 5 to 10 microns, and are distributed in the creped staple fiber nonwoven fabric in a weight ratio of 40:60 to 95: 5. For such a material structure, the acoustic effect is thus produced: the use of more microfibers allows for a larger internal surface area in the nonwoven fabric, thereby doubling the kinetic energy of the sound waves into heat energy. A disadvantage of the nonwoven fabric is that the air flow resistance in the individual layers cannot be set or adjusted, as a result of which the sound absorption properties of the sound-insulating nonwoven fabric are not optimal.

Furthermore, DE 10163576B4 discloses an insulating material for sound absorption and thermal insulation, which consists of two different thermoplastic matrix fibers (in the range of 0.8 to 1.7 dtex) and a thermoplastic melt fiber component (2.2 dtex). Whereby the average fiber diameter in the entire nonwoven fabric reached 1.3 dtex. Obviously, by reducing the use of binder fibers (10% of the fiber mixture), a nonwoven fabric is produced that possesses good drape characteristics and also has the internal strength of the nonwoven fabric, the latter being achieved due to mechanical and thermal strengthening. It is not possible to tailor the acoustic properties of the isolation material, either, subject to the process. Furthermore, the absorption properties of the sound waves cannot be further improved by using finer staple fibers, since according to the current state of the art finer fibers below 0.5dtex cannot be reliably processed on a carding machine.

EP1058618B1 describes an acoustically absorbent laminate composed of an apertured carrier layer and an apertured second fibrous layer. For a perforated carrier layer, a grammage of less than 2000g/m is involved²A web of less than 50 mm in thickness, or a density of 16 to 32kg/m³And an ultra-light plastic foam having a thickness of at least 6 mm. The second, apertured, fibrous layer is made from meltblown microfibers having a fiber diameter preferably between 2 and 5 microns. Also described are 500 to 4000Ns/m³The resistance to airflow of (a). By the stacked structure of the sound-absorbing film laminate, a flow layer is provided, which can be acoustically tuned. The disadvantage of this type of joint lies in the fact that: the carrier layer does not show a significant acoustic dependence.

EP 3375923a1 shows an acoustic absorbent textile composite material, in particular a nonwoven composite material, comprising:

a) at least one carrier layer comprising coarse staple fibers having a titer of 3 to 17dtex and fine staple fibers having a titer of 0.3 to 2.9dtex, more preferably 0.4 to 2.9dtex, in particular 0.5 to 2.9dtex, as skeleton fibers (Gerstfasern), and

b) a microporous flow layer disposed on the carrier layer, the flow layer comprising ultrafine fibers having a fiber diameter of less than 10 microns, wherein the sound absorbing textile composite has a flow resistance of 250Ns/m³To 5000Ns/m³Preferably 250Ns/m³To 4000Ns/m³More preferably 250Ns/m³To 3000Ns/m³In particular 250Ns/m³To 2000Ns/m³。

The sound-absorbing material exhibits very good sound-absorbing properties in the frequency range of 800Hz to 2000Hz, which is essential for the automotive industry. In addition, the sound absorption is easy to adjust, and the material can be produced with high compressibility and very good resilience at low grammage. With regard to the advantageous acoustic properties of the combination of fine and coarse staple fibers in the carrier layer, reference can be made to EP 3375923a 1.

Disclosure of Invention

The present invention is based on EP 3375923a1, the object of which is to provide a sound-absorbing material which preferably shows improved acoustic properties in the high frequency range, for example from 3000Hz to 10000Hz, and/or 4000Hz to 8000Hz, and/or 5000Hz to 6300 Hz.

This object is achieved by a sound-absorbing textile composite material, in particular a composite nonwoven fabric, comprising:

a) a first apertured carrier layer comprising as skeleton fibers thick staple fibers having a titer of 3 to 17dtex and thin staple fibers having a titer of 0.3 to 2.9dtex, more preferably 0.4 to 2.9dtex, especially 0.5 to 2.9 dtex; and

b) a microporous flow layer disposed on the first apertured support layer comprising microfibers having fiber diameters less than 10 micrometers;

c) a second apertured carrier layer comprising as skeleton fibers coarse staple fibers having a titer of 3 to 17dtex and fine staple fibers having a titer of 0.3 to 2.9dtex, more preferably 0.4 to 2.9dtex, in particular 0.5 to 2.9dtex, wherein the second apertured carrier layer is arranged on that side of the microporous flow layer which faces away from the first apertured carrier layer;

d) an additional microporous flow layer comprising microfine fibers having a fiber diameter of less than 10 microns, wherein said additional microporous flow layer is disposed on the side of the second apertured support layer facing away from said microporous flow layer.

Wherein the sound-absorbing textile composite material has a flow resistance of 250Ns/m³To 5000Ns/m³Preferably 250Ns/m³To 4000Ns/m³More preferably 250Ns/m³To 3000Ns/m³In particular 250Ns/m³To 2000Ns/m³。

It has surprisingly been found that the sound absorber according to the invention has better acoustic properties in the high frequency range, in particular in the range from 3000Hz to 10000Hz, than described in EP 3375923a 1. In addition, the above-mentioned disadvantages of the prior art can be avoided with the textile composite material according to the invention. Good acoustic performance in the high frequency range is particularly advantageous for electric vehicles, since the inverter generates high frequency noise.

It is hypothesized that the surprisingly high sound absorption coefficient is due to the combination of the flow layer and the synergistic interaction between the fine and coarse fibers of the carrier layer. It is hypothesized that the particular choice of fine staple fibres having a titre of 0.3 to 2.9dtex, in particular 0.5 to 2.9dtex, and coarse staple fibres having a titre of 3 to 17dtex, in the carrier layer, enables a particularly suitable framework structure for sound absorption, which framework structure is itself capable of absorbing sound waves. By a suitable selection of the fine and coarse staple fibers, the carrier layer can be given a high compressibility and a high resilience, whereby the flow layer on the carrier layer can optimally enter into vibrations and thus can absorb sound energy particularly effectively in accordance with the mode of action of the "flexplate absorber".

Furthermore, the combination of the apertured carrier layer with the microporous flow layer enables easy, targeted adjustment and variability of the acoustic properties of the textile composite. It was further found that the textile composite material according to the invention can be manufactured with high compressibility and good resilience, while the grammage is low. The textile composite material of a preferred embodiment of the present application thus has a compressibility of from 70% to 100%, more preferably from 75% to 100%, in particular from 80% to 100%; and/or have a resilience of from 70% to 100%, more preferably from 75% to 100%, especially from 80% to 100%. The textile composite material can thus be easily compressed and thus at the same time be well positioned in the intended installation space, since it can be recoiled well in the installation space by good resilience. This makes it possible to fit into installation spaces having complex geometries and different thickness dimensions.

The carrier layer can in principle be a woven, knitted and/or nonwoven fabric. According to the application, the carrier layer is preferably a nonwoven fabric according to DIN EN ISO 9092, from which a composite nonwoven fabric is formed.

The coarse staple fibers of the carrier layer have a fiber titer of 3 to 17 dtex. In a preferred embodiment, the fiber titer amounts to 3dtex to 12dtex, in particular 3dtex to 9 dtex. The coarse staple fibers give the textile composite the necessary structure and ensure that the textile composite also remains dimensionally stable in the installed state.

If the carrier layer does not contain binding fibers, in a preferred embodiment of the present application, the carrier layer contains coarse staple fibers in a proportion of 10 to 90 wt.%, more preferably 10 to 80 wt.%, still more preferably 10 to 70 wt.%, still more preferably 10 to 60 wt.%, still more preferably 10 to 50 wt.%, especially 10 to 40 wt.%, based on the total weight of the respective carrier layer. If the carrier layer contains binder fibers as further fibers, the proportion of coarse staple fibers is preferably 5 to 90 wt.%, more preferably 5 to 80 wt.%, more preferably 5 to 70 wt.%, even more preferably 5 to 60 wt.%, even more preferably 5 to 50 wt.%, even more preferably 5 to 40 wt.%, especially 5 to 30 wt.%, based on the total weight of the respective carrier layer.

The fine staple fibers of the carrier layer of the textile composite material according to the application have a fiber titer of 0.3dtex to 2.9dtex, in particular 0.5dtex to 2.9 dtex. In a preferred embodiment, the fine staple fibers have a fiber titer of up to 0.5dtex to 2.5dtex, in particular 0.5dtex to 2.0 dtex. By using fine short fibers in the carrier layer, sound energy can also be converted into heat in this layer due to the much larger inner surface of the carrier layer.

If the carrier layer does not contain binding fibers, in a preferred embodiment of the present application, the carrier layer comprises fine short fibers in a proportion of 10 to 90 wt.%, more preferably 20 to 90 wt.%, more preferably 30 to 90 wt.%, more preferably 40 to 90 wt.%, still more preferably 45 to 90 wt.%, still more preferably 50 to 90 wt.%, especially 55 to 90 wt.%, based on the total weight of the respective carrier layer. If the carrier layer comprises binder fibers as further fibers, the carrier layer comprises a proportion of fine staple fibers of from 5 wt.% to 90 wt.%, more preferably from 10 wt.% to 90 wt.%, more preferably from 20 wt.% to 90 wt.%, still more preferably from 30 wt.% to 90 wt.%, still more preferably from 40 wt.% to 90 wt.%, still more preferably from 50 wt.% to 90 wt.%, in particular from 55 wt.% to 90 wt.%, based on the total weight of the respective carrier layer.

According to the present application, the skeletal fibers are staple fibers. Unlike the binder fibers that may be included in each carrier layer, the backbone fibers do not, or only insubstantially, melt. Unlike filaments, which theoretically have an infinite length, staple fibers have a finite fiber length. According to the present application, the fine short fibers and the coarse short fibers preferably used as the skeleton fibers have a fiber length of 20 to 80mm, more preferably 25 to 80mm, and particularly 30 to 80mm, independently of each other. As the skeleton fiber, natural fiber, synthetic fiber, or a mixture thereof can be used. Synthetic fibers are preferably used.

In a preferred embodiment of the present application, the fine staple fibers and the coarse staple fibers used as the skeleton fibers contain, independently of each other, at least a polymer selected from the group consisting of: polyacrylonitrile, polyvinyl alcohol, viscose, polyamides, in particular polyamide 6 and polyamide 6.6, preferably polyolefins, in particular polypropylene, particularly preferably polyesters, in particular polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, mixtures and/or copolymers of the aforementioned substances. Preferably the backbone fibre contains at least one polymer in a proportion of 90 wt.%, more preferably 95 wt.%, especially more than 97 wt.%.

In a particularly preferred embodiment of the present application, the skeleton fiber comprises at least one polymer selected from the group consisting of: polyesters, in particular polyethylene terephthalate, polyolefins, mixtures or copolymers of the aforementioned. In a particularly preferred embodiment of the invention, the skeleton fiber is a polyester fiber, in particular polyethylene terephthalate. The advantage of this is the self-extinguishing flame behavior of polyethylene terephthalate, which in turn is relevant for the use of textile composites in the automotive field.

In addition to the fine and coarse staple fibers, the carrier layer can also contain other fibers. According to the invention, it is preferred that each carrier layer independently contains at least partially melted binder fibers as further fibers. As the binder fiber, fibers generally used for this purpose may be employed as long as they are capable of being at least partially heat-fused. The binder fibers may be single fibers or multicomponent fibers. Particularly suitable binder fibers according to the present application are the following fibers: the melting point of the binding component of the fiber is below the melting point of the backbone fiber to be bound, preferably 250 ℃ or below, more preferably in the range of 70 to 235 ℃, still more preferably in the range of 90 to 225 ℃, and particularly preferably in the range of 110 to 200 ℃. Suitable binder fibers are, in particular, fibers which contain and/or consist of: thermoplastic polyesters and/or copolyesters, in particular polybutylene terephthalate; polyolefins, in particular polypropylene; a polyamide; polyvinyl alcohol; and copolymers and mixtures thereof.

Particularly suitable binder fibers according to the present application are multicomponent fibers, preferably bicomponent fibers, especially core/shell fibers. The core/shell fibers comprise at least two fiber polymers having different softening and/or melting temperatures. Preferably, the core/shell fibers are composed of both fiber polymers. Wherein the component with the lower softening and/or melting temperature is present at the surface (shell) of the fiber and the component with the higher softening and/or melting temperature is present in the core.

In core/shell fibers, the bonding function may be achieved by a material disposed on the surface of the fiber. For the shell, various materials may be used. According to the application, preferred materials for the shell are polybutylene terephthalate, polyamide, polyethylene, copolyamides and/or copolyesters. Various materials may be used for the core as well. According to the application, the preferred materials for the core are polyesters, in particular polyethylene terephthalate and/or polyolefins.

According to the present application, the use of core-shell binder fibers is advantageous because it enables a particularly uniform distribution of the binder component in the nonwoven fabric. In addition, bicomponent fibers also have advantages over conventional binder fibers with respect to acoustic properties. Thus, in contrast to conventional binder fibers, when the binder component melts, the fiber core is retained. However, this is more effective than the melted binder component in terms of sound absorption properties.

If the carrier layer contains binder fibers as further fibers, the carrier layer preferably contains binder fibers in a proportion of from 5 to 50 wt.%, more preferably from 5 to 45 wt.%, even more preferably from 5 to 40 wt.%, in particular from 5 to 30 wt.%, based on the total weight of the respective carrier layer.

According to the application, it is preferred that the carrier layer is bonded and solidified by means of at least partially melted bonding fibers. The at least partially melted binder fibers are preferably melted without mechanical stress, for example, with a continuous furnace. Among other benefits, nonwoven fabrics can be manufactured to have a large volume without losing volume through mechanical action. In another preferred embodiment of the present application, the volume ratio of air to fiber in each carrier layer is, independently of each other, from 75:1 to 250:1, more preferably from 100:1 to 225:1, especially from 125:1 to 200: 1.

In another embodiment of the application, at least one of the carrier layers is bonded, preferably additionally reinforced with bonding fibers. As binders it is possible to use polyacrylates, polystyrenes, polyvinyl acetates, polyurethanes and mixtures and copolymers thereof.

According to the application, it is preferred that at least one of the carrier layers is easily reinforced, so that the sound-absorbing textile composite is easily draped and compressed, and thus can be applied in different installation spaces.

The carrier layer can in principle be a woven, knitted and/or nonwoven fabric. According to the application, at least one of the carrier layers preferably uses a nonwoven fabric according to DIN EN ISO 9092, whereby a composite nonwoven fabric is formed.

A microporous flow layer is understood to mean, according to the present application, a microporous layer which has a specific flow resistance, in particular greater than 250Ns/m³E.g. 250Ns/m³To 5000Ns/m³Preferably 250Ns/m³To 4000Ns/m³More preferably 250Ns/m³To 3000Ns/m³Especially 250Ns/m³To 2000Ns/m³. Advantageously, the carrier layer is provided with a flow layer, so that the sound absorption properties of the carrier layer can be improved. The grammage of the carrier layer can thereby be kept low and the product has outstanding acoustic properties.

The adjustment of the flow resistance of the flow layer can be achieved by targeted adjustment of the porosity and thickness in a manner and method known to the person skilled in the art. For a material that is too porous, sufficient friction will not be generated on the fibers and therefore kinetic energy will not be efficiently converted to thermal energy and thus less likely to be absorbed. In contrast, for a material that is too dense, the acoustic waves will be reflected primarily at the surface of the material and therefore may not be absorbed into the material.

According to the present application, the flow layer comprises microfine fibers having a fineness of 10 microns or less, preferably from 0.5 to 5 microns, more preferably from 1 to 3 microns. The use of ultra-fine fibers is advantageous in that very large internal surfaces are provided in the nonwoven fabric by the very small fiber diameter, on which surfaces sound energy can be absorbed particularly well. Fibers having such a fineness (meltblown fibers) can be obtained in a simple manner, for example, by means of a meltblown method, whereby a meltblown fiber nonwoven fabric is formed. The use of meltblown fibers is advantageous in that nonwoven fabrics having a high density and good acoustic properties can be obtained in a simple manner.

As the ultrafine fibers used for the fluidized bed, synthetic fibers are preferably used. Such fibers are preferably composed of at least one polymer selected from the group consisting of: polyolefins, in particular polypropylene; polyethylene terephthalate; a polyamide; mixtures and/or copolymers of the above. Preferably, the microfine fibers contain the above polymers, mixtures and/or copolymers in a proportion of at least 90 wt.%, more preferably of more than 95 wt.%, in particular of more than 97 wt.%.

Preferably, the flow layers independently of each other have an amount of microfine fibers of more than 50 wt.%, more preferably more than 70 wt.%, especially more than 90 wt.%, based on the total weight of each flow layer.

It is contemplated that the textile composite material according to the present application may be comprised of only two carrier layers and two flow layers. According to the application, the textile composite preferably also has further layers, in particular at least one cover layer arranged on the outer flow layer. Wherein it is advantageous that the flow layer can be better protected against damage. It has proven particularly suitable to use a melt-spun nonwoven as a cover layer. Preferably, the grammage of the cover layer is 50g/m²Below, for example, 12g/m²To 30g/m². Also haveThe cover layer is advantageously composed of thermoplastic filaments, in particular polypropylene filaments and/or polyethylene terephthalate filaments.

In a preferred embodiment, the textile composite material according to the invention has a third microporous flow layer on the side of the first apertured carrier layer facing away from the microporous flow layer, which third microporous flow layer comprises ultrafine fibers having a fiber diameter of less than 10 micrometers. Among these are the symmetrical structure of the textile composite material, which simplifies the use (Verbau). The third microporous flow layer may also be provided with a cover layer.

The carrier layer, the flow layer and the possible cover layer can be brought together in various ways. It is therefore conceivable to bond the layers to one another with an adhesive material. If a flow layer in the form of a meltblown nonwoven fabric is used, in a preferred embodiment of the present application the flow layer is prepared by spraying meltblown fibers directly onto a carrier layer. This makes it possible to obtain a composite nonwoven fabric in which no clear phase boundary is identified between the carrier layer and the flow layer. This makes it possible to adjust the fiber titer gradient in the boundary region of the carrier layer and the flow layer, which beneficially affects the acoustic properties. Furthermore, an additional adhesive layer can be dispensed with, which likewise advantageously influences the acoustic properties.

In a preferred embodiment of the invention, the layers, in particular the first, microporous flow layer, the second, microporous flow layer, the additional microporous flow layer and the possibly present third microporous flow layer and the possibly present cover layer, are bonded to one another only at their edges.

According to the application, the textile composite material has a flow resistance of 250Ns/m³To 5000Ns/m³Preferably 250Ns/m³To 4000Ns/m³More preferably 250Ns/m³To 3000Ns/m³Especially 250Ns/m³To 2000Ns/m³And/or 350Ns/m³To 5000Ns/m³Preferably 450Ns/m³To 5000Ns/m³More preferably 550Ns/m³To 5000Ns/m³And/or 350Ns/m³To 2000Ns/m³More preferably 450Ns/m³To 2000Ns/m³In particular 550Ns/m³To 2000Ns/m³. It is also conceivable that the flow resistance of the textile composite is in the range of 2000Ns/m³And 5000Ns/m³E.g. 2001Ns/m³To 5000Ns/m³. The flow resistance of the textile composite is equal to the sum of the flow resistance of the carrier layer and the flow resistance of the flow layer. Wherein the flow layer generally contributes significantly more to the flow resistance. The adjustment of the flow resistance can be achieved in a simple manner by selecting a suitable flow layer with the desired flow resistance.

With the textile composite material according to the application, outstanding sound absorption levels can be achieved, the sound absorption coefficient always being greater than 0.85, more preferably always greater than 0.90 (at a grammage of 350 g/m) in the measurement range from 3000Hz to 10000Hz²And a thickness of 20mm, in accordance with DIN EN ISO 354:2003 to perform measurements).

The grammage of the textile composite material is preferably 50g/m²To 500g/m²More preferably 100g/m²To 450g/m²In particular 150g/m²To 400g/m². It is advantageous for such grammage to be able to provide a textile composite material that is lightweight, thereby enabling reduced emissions in automobiles due to the reduced weight.

The thickness of the textile composite material is preferably from 5mm to 40mm, more preferably from 10mm to 35mm, in particular from 15mm to 30 mm. It is beneficial for the thickness to be at least 10mm to produce a large wall spacing so that the medium and long wavelengths of the mid and low frequency sound waves can also be absorbed into the textile composite.

A further subject matter of the present application is a process for producing a textile composite material according to the invention, which has a flow resistance of 250Ns/m³To 5000Ns/m³The method comprises the following steps:

a) providing and/or producing at least two apertured carrier layers comprising as skeleton fibres thick staple fibres having a titre of 3 to 17dtex and thin staple fibres having a titre of 0.5 to 2.9 dtex;

b) providing and/or preparing at least two microporous flow layers comprising microfibers having fiber diameters of less than 10 micrometers;

c) placing the flow layer on the carrier layer;

d) joining the carrier layer and the flow layer.

If a flow layer in the form of a meltblown nonwoven fabric is used, the flow layer may also be prepared by spraying meltblown fibers directly onto a carrier layer.

Providing and/or preparing at least one apertured carrier layer may be accomplished by preparation processes known to those skilled in the art, such as those used for dry-laid staple nonwoven fabrics. Suitable preparation processes for the carrier layer according to the invention are, for example, carding processes, and also aerodynamic processes, such as, for example, the Airlaid process (Airlay-Verfahren) and the air-deposition process (Airlay-Verfahren). In the classical carding process, staple fibers are broken down into individual fibers, typically using a hand-guided roll (Arbeiter-Wenderwalzen), and deposited as a rib yarn. These fibers can then be doubled, for example by a stacker (Kreuzleger), to form a single-layer or multi-layer web. The aerodynamic method is particularly suitable if a nonwoven fabric is produced in which the fiber arrangement is randomly oriented. Random orientation is advantageous because a voluminous, compression-elastic web can thereby be obtained, while having a low density. If binder fibers are used, the binder fibers can be heated to a melting point, for example, in a continuous furnace, thereby serving to cure the nonwoven fabric. The heat curing can be carried out before, during and/or after the joining between the carrier layer and the flow layer. Other non-contact curing means are also possible, such as application of an adhesive. It is particularly preferred that the nonwoven is cured in a non-mechanical curing process, in particular without needling, since this does not adversely affect the bulk of the carrier layer.

The flow layer can likewise be prepared by means and methods known to the person skilled in the art. Particularly preferred according to the invention is a melt blowing process. Among other things, it is advantageous to be able to produce fine fibers in a simple manner in one process step at low cost.

The joining between the carrier layer and the flow layer can be effected in a manner known to the person skilled in the art, for example by means of a hot-melt adhesive (Schmelzklebstoff) or an adhesive (Haftklebstoff). Preferably, the hot melt adhesive or mastic is applied in-line (inline) to the carrier layer while the flowable layer is conveyed in-line by an unwinder (abbickler).

Joining of the layers may also be achieved by thermally consolidating thermoplastic fibers contained in the layers. Preferably, the thermal curing of the layer takes place only at the edges.

If at least one microporous flow layer in the form of a meltblown nonwoven fabric is used, it is in a particularly preferred embodiment of the invention spun directly onto the carrier layer. This makes it possible to obtain a composite nonwoven fabric in which no distinct phase boundary is discernible between the carrier layer and the flow layer. This makes it possible to adjust the fiber fineness gradient in the boundary region of the carrier layer and the flow layer, which in turn advantageously influences the acoustic effect. In addition, an additional adhesive layer can be dispensed with, which in turn advantageously affects the acoustic properties.

In order to protect the outermost flow layer, this layer is optimally provided with a cover layer, as described above. This is particularly beneficial for meltblown nonwovens.

The textile composite material according to the invention is outstandingly suitable for sound absorption in the automotive field, for example for textiles for acoustic components of the interior of automobiles, in particular as sound-absorbing linings in interior trims of automobiles.

Drawings

FIG. 1: the sound absorption coefficient in the Alpha cabin according to example 3 of the invention (DIN EN ISO 354: 2003) is compared with that of comparative examples 1 and 2.

The invention will be further illustrated with reference to a number of examples.

Detailed Description

1. Comparative example 1

The prepared gram weight is 260g/m²A 20mm thick staple nonwoven fabric of fine polyethylene terephthalate (PET) staple fibers (35 wt.%), having a denier of 1.0dtex, polypropylene (PP) staple fibers (40 wt.%), having a denier of 2.0dtex, and coarse PE staple fibers (6.7 dtex)T staple fibers (15 wt.%), and PET/co-PET bicomponent fibers (10 wt.%) having a denier of 2.2 dtex. These staple fiber nonwoven fabrics were applied with a grammage of 45g/m²And a polypropylene melt-blown nonwoven fabric having a thickness of 0.5mm and an average fiber diameter of 2.5 μm.

2. Comparative example 2

Providing a grammage of 260g/m²And 20mm thick, consisting of fine PET staple fibers (35 wt.%) having a fineness of 1.0dtex, PP staple fibers (40 wt.%) having a fineness of 2.0dtex, coarse PET staple fibers (15 wt.%) having a fineness of 6.7dtex, and PET/co-PET bicomponent fibers (10 wt.%) having a fineness of 2.2 dtex. The short fibers are thermally bonded. Applying a grammage of 45g/m to both sides of the staple fiber nonwoven fabric²And a polypropylene melt-blown nonwoven fabric having a thickness of 0.5mm and an average fiber diameter of 2.5 μm.

3. Inventive example 3

Two kinds of the particles are provided, each of which has a density of 130g/m²Short-staple nonwoven fabric of grammage and thickness 10mm, consisting of fine PET staple fibers (35 wt.%) with a titer of 1.0dtex, PP staple fibers (40 wt.%) with a titer of 2.0dtex, coarse PET staple fibers (15 wt.%) with a titer of 6.7dtex, and PET/co-PET bicomponent fibers (10 wt.%) with a titer of 2.2 dtex. The staple fiber nonwoven is thermally bonded. A first staple fiber nonwoven fabric is prepared. Applying a basis weight of 45g/m on the first nonwoven²And a polypropylene melt-blown nonwoven fabric having a thickness of 0.5mm and an average fiber diameter of 2.5 μm. Another staple nonwoven fabric was applied to the polypropylene melt-blown nonwoven fabric and another polypropylene melt-blown nonwoven fabric was applied thereto.

4. Determining sound absorption coefficient

The sound absorption coefficient of example 3, comparative examples 1 and 2 was measured in accordance with DIN EN ISO 354: 2003. The results are shown in FIG. 1.

It can be seen that example 3 has excellent sound absorption performance in the frequency range of 3000Hz to 10000Hz, which is particularly important for electric vehicles. Although the parameters relating to sound absorption (grammage and thickness) are the same, they are much better than comparative examples 1 and 2.

In order to determine the parameters used according to the invention, the following measurement methods were used:

test method for nonwoven fabrics for determining grammage

According to ISO 9073-1, wherein the area of the test specimen amounts to 100mm x 100 mm.

Test method for nonwoven fabrics for determining thickness

According to DIN EN ISO 9073-2, methods B and C.

Determination of fiber titer

The fiber diameter was determined according to DIN 53810 (fineness of textile fibers-concept and test principle) with the aid of a microscope and corresponding software. Preparing 4 microscopic specimens with more than 20 single fibers

For each microscopic specimen, the fibers were cut down to about 2-3 mm long with scissors and placed on slides with the aid of dissecting needles

The above. The fiber diameter (micrometers) was then determined and reported with the aid of corresponding software. The reported fiber diameter can then be converted to a fiber titer Tt by means of the following equation:

d fiber diameter in microns

ρ g/cm³Density of fiber as unit

Determination of short fiber length

From an existing fiber sample, 10 fiber bundles were selected, wherein a single fiber was taken out of each of the 10 fiber bundles by means of tweezers, and by clamping the fiber free end into one of two clamping jaws, the second free end of the fiber was clamped into the remaining one of the clamping jaws to determine the fiber length of the 10 single fibers. By rotating the handwheel, the fiber is stretched until it is not crimped. The length of the fiber is read from the scale of the tester and is marked in millimeters. The average of all the results obtained represents the staple length:

sum of lengths of single fibres of Sigma L

number of n samples

Determination of melting Point

Dynamic differential thermal analysis (DSC) according to DIN EN ISO 11357-3, part 3: the melting and crystallization temperatures, and the enthalpy of fusion and crystallization were determined, with a heating rate of 10K/min being used.

Determining compressibility

By reference to DIN 53885 (determination of the compressibility of textiles and textile products), the determination of the compressibility is achieved by means of other measuring devices as described in the standard. Thus, a test specimen having a size of 100mm x 100mm, a measuring table (Messtafel) having a length dimension of mm, a metal plate having a size of 120 mm x 120 mm, and a cylindrical weight having a diameter of 55 mm and a mass of one kilogram were prepared.

Before the measurement, the thickness of the test specimen is determined with the aid of the measuring table in the unloaded state. This value describes the initial thickness d in millimeters₀. After determining the initial thickness in the unloaded state, the next step is to place a metal plate (100g) on the test specimen and align it with the center. A circular weight was then placed on the circular mark of the measuring plate, and thus the test specimen was loaded by about 1.1 kg. The absolute compressibility of the test specimen is determined by the following equation, which reflects the difference between the initial thickness and the thickness under load:

K₂[mm]＝d₀-d_b

d₀initial thickness in millimeters

d_bFinal thickness in millimeters of the test specimen in the respective loaded state

The relative compressibility Kr expressed in percentage is:

determining rebound resilience

Reference is made to DIN EN ISO 1856 (Soft elastic Polymer foam-determination of the compression set residue). As the measuring means, the same structure was used as described in the section "determination of compressibility". In determining the resilience, the difference between the initial thickness and the final thickness of the material is determined at a certain temperature and a fixed recovery time after a certain time of compression set.

Before the measurement, the thickness of the test specimen is determined with the aid of a measuring table in the unloaded state. This value describes the initial thickness in millimeters. After determining the initial thickness in the unloaded state, the next step is to place a metal plate (100g) on the specimen with its center aligned. A cylindrical weight was then placed on the circular mark of the measuring plate and the test specimen was loaded with about 1.1kg over a period of 24 hours and at room temperature (23 ℃ +/-2 ℃). After 24 hours loading, the weight and the metal plate were removed from the test specimen and the thickness of the test specimen was measured again after a 30 minute recovery period, the compression set residue being determined as follows:

d₀initial thickness of test body in millimeters

d_rThickness of test body after recovery

The resiliency of a material can be calculated from the compression set residual using the following equation:

R[％]＝100-DVR

determining the air: volume ratio of fiber

The air to fiber volume ratio provides information about the porosity of the material. Thus, assuming a high proportion of air compared to the fibres,the material has a high porosity. Volume ratio V_{Air (a)}Ratio V_FiberCan be determined as follows. To this end, the volume of the test body is first calculated using the following formula:

V_{test body}[cm³]＝l*b*d

length of test body in l mm

Width of test body in units of b mm

The thickness of the test bodies in d mm is measured in accordance with DIN EN ISO 9073-2, methods B and C

After the volume of the test body was determined, the volume of the fibers contained in the nonwoven fabric was determined in the next step using the following formula:

m_fiberFiber mass of test body in grams

ρ_{Fibrous polymers}In g/cm³Density of fibrous polymer as unit

Preferably, short fibers made of the polymer polyethylene terephthalate are used in the carrier layer, so that it can be from about 1.38g/cm³The fiber density of (a) begins. After the fiber volume has been calculated, the air volume can now be determined in the next step by means of the following formula:

V_{air (a)}[cm³]＝V_{Test body}-V_Fiber

If the air volume and the fibre volume of the test body are determined, the two volume values can now be used to set the relationship with respect to one another.

Test method for determining flow resistance

According to DIN EN 29053, method A (air flow method), the effective sample diameter is 100mm and the air pressure is 1000 mbar.

Test method for measuring sound absorption in reverberation room (Alpha cabin)

According to DIN EN ISO 354:2003, measurements were made in Alpha chamber. The test specimens were placed directly on the base plate.

Claims

1. Flow resistance of 250Ns/m³To 5000Ns/m³In particular a composite nonwoven fabric, comprising:

a) a first holed carrier layer containing coarse short fibers and fine short fibers as skeleton fibers, the coarse short fibers having a fineness of 3dtex to 17dtex, the fine short fibers having a fineness of 0.3dtex to 2.9dtex,

b) a microporous flow layer disposed on the first apertured support layer, the flow layer comprising microfibers having fiber diameters less than 10 micrometers,

it is characterized by also comprising:

c) a second apertured carrier layer comprising coarse staple fibers and fine staple fibers as skeletal fibers, said coarse staple fibers having a denier of from 3dtex to 17dtex and said fine staple fibers having a denier of from 0.3dtex to 2.9dtex, wherein said second apertured carrier layer is arranged on the side of said microporous flow layer facing away from said first apertured carrier layer; and

d) an additional microporous flow layer comprising microfibers having a fiber diameter of less than 10 micrometers, wherein the additional microporous flow layer is disposed on a side of the second apertured support layer facing away from the microporous flow layer.

2. The sound absorbing textile composite material according to claim 1, wherein the sound absorbing textile composite material has a compressibility of 70% to 100%, more preferably 75% to 100%, in particular 80% to 100%, and/or a resilience of 70% to 100%, more preferably 75% to 100%, in particular 80% to 100%.

3. The sound absorbing textile composite of claim 1 or 2, wherein the first and/or second carrier layer of apertures is a non-woven fabric.

4. The sound-absorbing textile composite material according to one or more of the preceding claims, characterized in that the first and/or the second apertured carrier layer contain as further fibers at least partially fused binder fibers, in particular core/shell fibers.

5. The sound absorbing textile composite according to any one or more of the preceding claims, wherein the first and/or second apertured carrier layer is/are free of binder fibres, said carrier layers independently of each other comprising coarse staple fibres in a proportion of 10 to 90 wt.%, more preferably 10 to 80 wt.%, in particular 10 to 70 wt.%, based on the total weight of the respective carrier layer; or the first and/or second apertured carrier layer contains binder fibres as further fibres, the proportion of coarse staple fibres being 5 to 90 wt.%, preferably 5 to 80 wt.%, in particular 5 to 70 wt.%, based on the total weight of the respective carrier layer.

6. The sound absorbing textile composite according to any one or more of the preceding claims, wherein the first and/or second apertured carrier layer is free of binder fibres, said carrier layers independently comprising fine staple fibres in a proportion of 10 to 90 wt.%, more preferably 20 to 90 wt.%, in particular 30 to 90 wt.%, based on the total weight of the respective carrier layer; or the first and/or second apertured carrier layer contains as further fibers binder fibers in a proportion of fine staple fibers of from 5 to 90 wt.%, preferably from 10 to 90 wt.%, in particular from 20 to 90 wt.%, based on the total weight of the respective carrier layer.

7. An acoustic textile composite material as claimed in any one or more of the preceding claims, wherein the fine staple fibres and the coarse staple fibres used as skeleton fibres have, independently of each other, a fibre length of 20mm to 80mm, more preferably the length is 25mm to 80mm, in particular 30mm to 80 mm.

8. The sound absorbing textile composite of any one or more of the preceding claims, wherein the first and/or second carrier layer of apertures is thermally bonded.

9. The sound absorbing textile composite according to any one or more of the preceding claims, wherein the first and/or second carrier layer has a volume ratio of air to fibres of from 75:1 to 250:1, more preferably from 100:1 to 225:1, in particular from 125:1 to 200: 1.

10. The sound absorbing textile composite material according to any one or more of the preceding claims, wherein at least one of said flow layers comprises ultra fine fibers, in particular melt blown fibers, having a denier of less than 10 microns, preferably from 0.5 microns to 5 microns, more preferably from 1 micron to 3 microns.

11. The sound absorbing textile composite of any one or more of the preceding claims, wherein the individual layers of the sound absorbing textile composite are bonded to each other only at the edges.

12. The sound absorbing textile composite material according to any one or more of the preceding claims, wherein said sound absorbing textile composite material has a grammage of 50g/m²To 500g/m²More preferably 100g/m²To 450g/m²In particular 150g/m²To 400g/m²。

13. The sound absorbing textile composite material according to any one or more of the preceding claims, wherein the sound absorbing textile composite material has a thickness of from 5mm to 40mm, more preferably from 10mm to 35mm, in particular from 15mm to 30 mm.

14. The manufacturing flow resistance is 250Ns/m³To 5000Ns/m³In particular 250Ns/m³To 2000Ns/m³The method of weaving a composite material, characterized in that it comprises the steps of:

a) providing and/or producing at least two perforated carrier layers, which carrier layers comprise coarse staple fibers and fine staple fibers as skeleton fibers, the fineness of the coarse staple fibers is 3dtex to 17dtex, and the fineness of the fine staple fibers is 0.3dtex to 2.9 dtex;

c) disposing the flow layer on the carrier layer;

d) joining the carrier layer and the flow layer.

15. Use of the sound-absorbing textile composite material according to one or more of claims 1 to 13 as sound absorber in the automotive field.