Needled sandwich nonwoven structure, and method of making it

Abstract

The disclosure provides needled sandwich material structures in which a core nonwoven with vertically oriented fibres is used; and a method of manufacturing these sandwich material structures.

Claims

1. A micro-perforated needle-punched sandwich nonwoven structure, having a core nonwoven with vertical fibre orientation, com-prising PET and/or PET/PP fibres and bonding fibres of PE, PP and/or BiCo fibre (coPET), wherein the core nonwoven being provided on one or both sides with cover materials wherein the area between the vertically oriented fibres of the core nonwoven contains interspersed identical or different filling materials of ground material, fibres, flakes and/or powder, wherein the cover materials are the same or different and each independently of each other comprises a nonwoven, woven, knitted fabric, paper or film.

2. The sandwich nonwoven structure according to claim 1, comprising a film between the core nonwoven and the cover materials.

3. A method of manufacturing sandwich nonwoven structures according to claim 1, wherein the fibres of a mechanically or aerodynamically formed nonwoven are oriented in-line in a vertical lay-up device in the range of predominantly 90° and 45°, spreads the oriented fibres/fibre layers, by a scattering device, filler materials are scattered between the vertically oriented fibres, the structure obtained is thermoset in an oven, after solidification, cover materials are fed in on one or both sides and needling the obtained composite in a needling unit.

4. The method according to claim 3, wherein comprising spreading the vertically oriented fibres of the core nonwoven by pairs of rollers, which (a) before and after the scattering device or (b) are arranged after the scattering device by a pair of roll-ers, wherein the pairs of rollers are controlled separately, if necessary.

5. A method of manufacturing sandwich nonwoven structures according to claim 2, wherein the fibres of a mechanically or aerodynamically formed nonwoven are oriented in-line in a vertical lay-up device in the range of predominantly 90° and 45°, spreads the oriented fibres/fibre layers, by a scattering device, filler materials are scattered between the vertically oriented fibres, the structure obtained is thermoset in an oven, after solidification, cover materials are fed in on one or both sides and needling the obtained composite in a needling unit.

6. The method according to claim 5, wherein comprising spreading the vertically oriented fibres of the core nonwoven by pairs of rollers, which (a) before and after the scattering device or (b) are arranged after the scattering device by a pair of rollers, wherein the pairs of rollers are controlled separately, if necessary.

Description

[0010] FIG. 1 shows an apparatus for manufacturing the microperforated needle-punched sandwich nonwoven structures 1 according to the invention and their basic manufacturing process. A mechanically or aerodynamically produced nonwoven 6 is fed to the vertical lay-up device 7 and the fibres are erected at an angle of approximately 90° to 45°. The thus “vertically laid” fibres are fed inline to a scattering device 8, which adds filling materials 4 to the fibres, which are held between the aforementioned fibres. The preform thus obtained is then fed to an oven 9 where the structure is thermoset. The composite thus obtained is then provided with a covering material 3a, 3b on one or both sides. In the subsequent needling unit 10, the entire composite is then needled to form the finished end product 1. FIG. 1 also shows the preferred embodiment in which, in addition to the cover materials 3a, 3b, a further film 5 is fed in here on one side between the core nonwoven 2 and the cover materials 3a, 3b. The film 5 is additionally fed—between the cover material 3a, 3b and the core fleece (2)—if acoustic or mechanical properties are to be influenced. If the cover material 3a,3b includes a film, then the additional film 5 is omitted.

[0011] FIG. 2 shows a variant of the apparatus according to FIG. 1. Following its passage through the scattering device 8, the non-woven obtained from the vertical lay-up device 7 is fed to a pair of rollers 11 and compressed and spread accordingly. Alternatively, FIG. 3 describes a process variant that comprises two pairs of rollers 12, 13, wherein the pair of rollers 12 is arranged upstream of the scattering device 8 and the pair of rollers 13 is arranged downstream of the scattering device.

[0012] No nonwoven structures are known in the prior art that have a vertical fibre orientation based on mechanical or aerodynamic nonwoven formation with needled cover webs, films or papers on one or both sides. Furthermore, there are no disclosures on the interspersing of different scattering materials between the vertical fibre orientations. Processes and plants for the production of such nonwoven structures are also not known.

[0013] In addition to covering the core nonwoven 2 on one side, it is also preferred to cover it on both sides with the above-mentioned cover materials 3a,3b. These can be the same or different, have different materials, different thicknesses, different densities, different flow resistances (air permeability), etc.

[0014] In a further embodiment, a film 5 is furthermore located on one or both sides between the core nonwoven 2 with vertical fibre orientation and the cover materials 3a, 3b; which is also microperforated by the needling of the overall composite. Materials of the film(s) include in particular PE/PA/PE and PA/PE. Pure PE films are also used. The films 5 essentially have a thickness in the range of 40 μm to 180 μm. If only one film fleece (PE/PA/PE+PET) is used as cover material (3a,b), thicknesses up to 450 μm are preferred. The weight per unit area of the nonwovens 3a,3b is preferably in the range of 60 to 450 g/m.sup.2.

[0015] A method according to the invention for the production of microperforated needle-punched sandwich nonwoven structures 1 (see FIG. 1), which makes it possible to feed a cover material 3a,3b in-line to a core nonwoven 2 with vertical fibre orientation at least on one side and to needle-punch the overall composite, is characterised in that

the fibres of a mechanically or aerodynamically formed nonwoven 6 are oriented in a vertical lay-up device 7 in the range of predominantly 90° and 45°,
spreads the oriented fibres/fibre layers,
by means of scattering device 8 scatters filling materials 4 between the vertically oriented fibres,
the structure obtained is thermoset in an oven 9,
after solidification, cover materials 3a, 3b are fed in on one or both sides and
needle the obtained composite in a needling unit 10.

[0016] It is advantageous if the oven 9 is equipped with two conveyor belts and two separate drives. By using different speeds of the upper and lower belt, the tightness of the oriented fibres/fibre layers can be adjusted independently of each other.

[0017] Furthermore, it is advantageous if different temperatures (top and bottom) can be set in the oven in the range of preferably 120 to 180° C., for example by means of special hot air slot nozzles transverse to the throughput direction, which can be controlled separately if necessary. In particular, it is advantageous that one can thus influence the properties of the fibre/scatter composite via the thickness.

[0018] The focus here is mainly on the cross-linking of the materials, namely the influence of the mechanical properties stiffness, strength and the processing behaviour in subsequent processes.

[0019] The spreading of the vertically (90°) to 45° oriented fibres/fibre layers is done, for example, by arranging a pair of rollers 11 in the direction of travel behind the scattering device 8, i.e. between the scattering device 8 and the oven 9 (see FIG. 2). The speed of the roller pair 11 can be variably adjusted and can be greater than the operating speed of the vertical lay-up device 7.

[0020] It is also possible to work with two pairs of rollers 12, 13. One pair of rollers 12 is arranged upstream of the scattering device 8 and one pair of rollers 13 is arranged downstream of the scattering device (upstream of the oven 9) (see FIG. 3). Both roller pairs 12 and 13 can be controlled separately.

[0021] Essential elements of the present invention are a micro-perforated needle-punched sandwich nonwoven structure in which acoustic, mechanical and processing properties are achieved, on the one hand, by scattering property-influencing scattering material into vertically oriented fibres and, on the other hand, the process of needle-punching this structure on one or both sides with nonwovens, wovens, knitted fabrics, paper or film. Furthermore, the in-line process for the production of such sandwich nonwoven structures, in particular by means of the integrated scattering plant, and precisely the scattering of scattering material into vertical fibre orientations, represents a novelty in the plant sector.

[0022] The advantage of the present invention lies in particular in the in-line production of micro-perforated needle-punched sandwich nonwoven structures with (in the core) vertical fibre orientation; in that, on the one hand, the acoustic, mechanical and processing properties of the nonwoven (and thus ultimately the component properties) can be influenced by the fibre orientation, the fibre mix, the fibre fineness of the core nonwoven and the scattering material contained therein and, on the other hand, by needling this scatter-filled core nonwoven formed with vertically oriented fibres with nonwovens, wovens, knitted fabrics, paper or film and thus provide new, property-optimised sandwich nonwoven structures.

[0023] The following materials, among others, are used as scattering material between the vertically oriented fibres of the core nonwoven with vertical fibre orientation, which influence the following properties:

Acoustics: Hollow fibres with different cross-sectional geometry, GF/BiCo/PET ground/fibrous material, foam flakes;
Water absorption: hydrophobised fibres (inter alia H-PET), GF/PP/BiCo ground/fibrous material;
Stone chipping: PP/PE ground/fibrous material;
Ice accumulation/adhesion: hydrophobised fibres (inter alia H-PET), PP/PET ground material;
Stiffness: carbon fibres, natural fibres;
Temperature resistance: PP/GF ground/fibre material, mineral fibres, glass fibres (GF);
Burning behaviour: GF/Panox/PET/BiCo ground/fibrous material, flame retardant, flame retardant treated fibre, mineral fibres, glass fibres;
Tear resistance: Aramid fibres.

[0024] The sandwich nonwoven structures according to the present invention are microperforated by needling. Microperforation in the sense of the present invention is defined by hole diameters in the range of 0.05 to 2.4 mm.

EXAMPLE OF EXECUTION

Example 1

[0025] According to the method of the invention, a commercial 500 g/m.sup.2 nonwoven 2 with vertically oriented fibres (65% PET/35% coPET) was interspersed with 50 g/m.sup.2 75% PP/25% PE ground/fibrous material 4, which was needled on both sides with an 80 g/m.sup.2 needled nonwoven (75% PET/25% PP) 3.

[0026] After forming into a wheel arch liner, comparative tests were made with a conventional wheel arch liner made with conventional nonwoven (800 g/m.sup.2 40% PP/30% PET/30% BiCo). Significant differences were found with regard to bending stiffness (10% increase), stone impact resistance (in shot through and weight loss) and deformation behaviour.

Example 2

[0027] According to the method of the invention,

a 1300 g/m.sup.2 nonwoven with vertically oriented fibres
(70% PET/30% coPET) 2, 100 g/m.sup.2 40%PP/30%PET/30% BiCo-ground material 4 was interspersed and then needle-punched on both sides with 150 g/m.sup.2 needled nonwoven (75% PET/25% PP) 3. Here, too, a significant improvement in the mechanical properties was seen after forming into an underbody shield, compared to the conventional underbody shield material structures.

LIST OF REFERENCE SIGNS

[0028] 1 sandwich nonwoven structure [0029] 2 core nonwoven [0030] 3a,3b cover material [0031] 4 filling material [0032] film [0033] 6 nonwoven [0034] 7 vertical lay-up device [0035] 8 scattering device [0036] 9 oven [0037] needling unit [0038] 11 pair of rollers [0039] 12 pair of rollers [0040] 13 pair of rollers