Cover Material for Covering an Airbag Unit

Abstract

The invention relates to a cover material for covering an airbag unit, comprising a textile carrier material (1) composed of threads and comprising a coating (2) based on thermoplastic materials applied to the textile carrier material (1) on the visible side, wherein the textile carrier material (1) has, in a longitudinal direction (L) and/or in the transverse direction (Q) orthogonal with respect thereto, linear regions (100) of lower strength than in the remaining regions (101), which linear regions form weakening lines (30) for the cover material (3), and along the weakening lines (30) the cover material has an ultimate tensile strength of 150 to 700 N and a tear propagation resistance of 3 to 45 N.

Claims

1.-13. (canceled)

14. A cover material for covering an airbag unit, comprising a textile carrier material composed of threads and comprising a coating based on thermoplastic materials applied to a textile carrier material on a visible side, wherein the textile carrier material has, in a longitudinal direction (L) and/or in the transverse direction (Q) orthogonal with respect thereto, linear regions of lower strength than in remaining regions, wherein the linear regions form weakening lines for the cover material, and along the weakening lines the cover material has an ultimate tensile strength of from 150 to 700 N and a tear propagation resistance of from 3 to 45 N.

15. The cover material as claimed in claim 14, wherein the weakening lines run parallel at a distance of 0.5 to 500 mm from one another.

16. The cover material as claimed in claim 14 having an ultimate tensile strength elongation of from 3 to 200% along the weakening lines.

17. The cover material as claimed in claim 14, wherein a separating force required to separate the textile carrier material from the coating in a temperature range between −40° C. and 120° C. is greater than 18 N/5 m.

18. The cover material as claimed in claim 14 having a weight per unit area of 300 to 1200 g/m.sup.2.

19. The cover material as claimed in claim 14, wherein in the linear regions of lower strength, the textile carrier material comprises threads which are thinner than in the remaining regions.

20. The cover material as claimed in claim 14, wherein in the linear regions of lower strength, the textile carrier material comprises threads which have a lower strength than in the remaining regions.

21. The cover material as claimed in claim 14, wherein the textile carrier material is formed on the basis of threads composed of polyester, polyamide, polyacetate, rayon, viscose and/or cotton.

22. The cover material as claimed in claim 21, wherein the textile carrier material is a woven fabric, knitted fabric or nonwoven.

23. The cover material as claimed in claim 14, wherein the textile carrier material has a thickness of 0.2 to 4.9 mm.

24. The cover material as claimed in claim 14, wherein the coating is formed on the basis of polyvinyl chloride (PVC), polyurethane (PUR), thermoplastic polyolefin (TPO), or mixtures thereof.

25. The cover material as claimed in claim 14, wherein the coating comprises a plurality of discrete successive layers.

26. The cover material as claimed in claim 14, wherein at least one varnish layer is applied to the coating on the visible side.

27. The cover material as claimed in claim 14, wherein the total thickness of the cover material is from 0.5 mm to 5 mm.

28. The cover material as claimed in claim 14 provided with a profiling at least in the region of the visible side.

29. The cover material as claimed in claim 14, wherein the coating has a thickness of from 0.1 to 4.8 mm.

30. The cover material as claimed in claim 14, wherein the textile carrier material has a thickness of from 0.2 to 4.9 mm.

31. The cover material as claimed in claim 14, wherein the textile carrier material is a warp-knit material composed of polyacetate fibers with a weight of 50-350 g/m.sup.2 and a thickness of 0.2-1.2 mm.

32. The cover material as claimed in claim 14, wherein the textile carrier material is a circular-knit material composed of 100% polyester fibers with a weight of 50-350 g/m.sup.2 and a thickness of 0.20-1.20 mm

33. The cover material as claimed in claim 14, wherein the coating is formed on the basis of polyurethane (PUR).

Description

[0024] The invention will be explained in further detail below on the basis of the drawing and the exemplary embodiments. In the drawing:

[0025] FIG. 1 is a greatly enlarged schematic illustration showing a section through a cover material according to the invention;

[0026] FIG. 2 is a schematic perspective illustration showing a partially sectioned construction of the cover material according to the invention.

[0027] FIG. 1 illustrates in a cross section a cover material 3 for covering an airbag unit (not shown here) in a motor vehicle interior, for example in the region of the dashboard.

[0028] The cover material has on its bottom side a textile carrier material 1 which is formed for example from polyester threads in the form of a woven fabric with warp threads running in a longitudinal direction L and weft threads running in a transverse direction Q; see FIG. 2.

[0029] A multilayered coating 2 is applied to this textile carrier material 1, with the layer coming to lie directly on the textile carrier material 1 being denoted by reference sign 20 and the subsequent layer applied discretely thereon being denoted by reference sign 21. These layers are for example compact layers on the basis of PVC or polyurethane, with in particular the layer 20 being tailored in its formulation in such a way that it enters into particularly intimate adhesion with the underlying textile carrier material 1, specifically at least in a temperature range between −40° C. and 120° C. The adhesion achieved brings about separating forces between the textile carrier material 1 and the coating of considerably more than 18 N/5 m.

[0030] A foamed layer 22, for example likewise on the basis of PVC or polyurethane, is applied to the compact layer 21 and imparts a pleasant soft and elastic feel to the entire coating 2. Above the foamed layer 22 there adjoins a further compact layer 23 composed of compatible plastic. The uppermost layer 24, which also forms the visible surface or visible side S, can be formed for example by a printed layer which, moreover, can also be provided with a surface profiling, for example in the form of a leather grain. Hence, the cover material 3 can be classified as artificial leather.

[0031] As can be seen in particular from the further illustration according to FIG. 2, linear regions 100 of lower strength than in the remaining regions 101 are formed in the textile carrier material 1 along the longitudinal direction L and also along the transverse direction Q orthogonal with respect thereto, said linear regions running parallel to one another and having for example a regular distance A from one another of approximately 1 mm. These linear regions 100 of lower strength are formed by virtue of the fact that the warp threads or weft threads each lying on the linear regions 100 have a lower strength than those threads which are woven in the remaining regions 101 to form the textile carrier material 1. This can be realized for example by using threads of smaller diameter in relation to the remaining regions 101. Although not illustrated for reasons of clarity, the linear regions 100 can be arranged at regular intervals over the entire longitudinal and/or transverse direction (L, Q).

[0032] The textile carrier material 1 thus has, along the linear regions 100 of lower strength at the desired spacing A, linear weakened regions which, after the coating 2 has been applied to the textile carrier material 1 to form the cover material 3, define weakening lines 30 within the obtained cover material 3 which run exactly along the course of the linear regions 100 of lower strength in the textile carrier 1. However, by virtue of the homogeneous coating 2 on the visible side of the textile carrier 1, they are not visually evident.

[0033] In the region of these weakening lines 30, the cover material 3 has an ultimate tensile strength of only 150-700 N, a tear propagation resistance of 3-45 N and an ultimate tensile strength elongation of 3-200% along the course of the weakening lines 30. Depending on the positioning, the latter can run either along the longitudinal direction L or along the transverse direction Q or both along the longitudinal direction L and the transverse direction Q.

[0034] However, when placing such a cover material 3 on an airbag unit (not shown here) for covering the latter, one of these weakening lines 30 comes reliably into overlap with the periphery of the airbag unit as a result of the small spacing A of the individual weakening lines 30 and causes the cover material to tear open along this weakening line 30 upon triggering of the airbag. No particular requirements or specifications are therefore placed on the positioning of the cover material 3 with respect to the course of the weakening lines 30 in relation to the airbag unit to be covered, which considerably simplifies the application and processing.

[0035] However, the by contrast considerably higher strength of the cover material 3 outside the weakening lines 30 ensures sufficient stability and stitchability of the cover material 3 for applications in the motor vehicle interior.

[0036] Further details become evident from the exemplary embodiments specified below, which nevertheless serve only to illustrate the invention and are not intended to limit it in any way:

[0037] For the formation of cover materials for covering an airbag unit in motor vehicle interiors, cover materials were produced from a bottom-side textile carrier material and coatings applied on the upper side in various embodiments and tested with regard to their tear-open properties.

[0038] The textile carrier material used was either a warp-knit material composed of 100% polyacetate fibers with a weight of 50-350 g/m.sup.2 and a thickness of 0.2-1.2 mm or a circular-knit material composed of 100% polyester fibers with a weight of 50-350 g/m.sup.2 and a thickness of 0.20-1.20 mm, in each case having linear regions of lower strength both in the longitudinal and transverse direction (Example 1) on the one hand and only in the transverse direction (Example 2) on the other hand and provided with the following examples of a coating.

TABLE-US-00001 PVC-based coating Example 1 Example 2 Total weight: 770 g/m.sup.2 740 g/m.sup.2 Total thickness: 1.0 mm 1.15 mm Burning: <100 mm/min <100 mm/min Tear propagation resistance: L 10 N 60 N Q 9 N 15 N Ultimate tensile strength: L 290 N/5 cm 350 N/5 cm Q 200 N/5 cm 200 N/5 cm Ultimate tensile strength L 25%  50% elongation: Q 37% 167% Separating force:  >18 N/5 mm  >18 N/5 mm

TABLE-US-00002 PUR-based coating Example 1 Example 2 Total weight: 530 g/m.sup.2 630 g/m.sup.2 Total thickness: 0.9 mm 1.05 mm Burning: <100 mm/min <100 mm/min Tear propagation resistance: L 9 N 55 N Q 7 N 12 N Ultimate tensile strength: L 270 N/5 cm 330 N/5 cm Q 180 N/5 cm 210 N/5 cm Ultimate tensile strength L 20%  54% elongation: Q 31% 155% Separating force:  >18 N/5 mm  >18 N/5 mm

TABLE-US-00003 TPO-based coating Example 1 Example 2 Total weight: 600 g/m.sup.2 650 g/m.sup.2 Total thickness: 1.0 mm 1.05 mm Burning: <100 mm/min <100 mm/min Tear propagation resistance: L 11 N 63 N Q 10 N 10 N Ultimate tensile strength: L 300 N/5 cm 370 N/5 cm Q 220 N/5 cm 220 N/5 cm Ultimate tensile strength L 30%  45% elongation: Q 29% 153% Separating force:  >18 N/5 mm  >18 N/5 mm

[0039] The cover materials obtained had a leather grain structure and could be finished by stitching as an artificial leather cover material for dashboards, door side linings and seat linings for covering airbag units in the motor vehicle interior, and ensured, without fixed positioning with respect to the airbag unit to be covered, a reliable tear-open behavior to deploy the airbag.