Method for introducing weaknesses into a decorative material

Abstract

The invention relates to a method for introducing weaknesses into a decorative material comprising a decorative layer and a carrier layer, preferably used for airbag coverings in motor vehicles, wherein the method comprises the following steps: a) introducing different weaknesses (21) by means of a laser (20) into sections (30) of the decorative material (10) for test purposes, wherein the different weaknesses (21) differ from one another in that the different weaknesses (21) are introduced using different parameters of the laser (20); b) measuring the tear properties of the sections (30); c) determining which section (30) which has a desired tear property and associating the relevant parameters of the laser (20) with this section (30); d) setting the laser (20) at the parameters associated in accordance with e); e) introducing weaknesses (22) into the decorative material (10) by means of the laser (20) set in accordance with step e).

Claims

1. A Method for introducing weaknesses into a decorative material, in particular airbag coverings in motor vehicles, wherein the method comprises the following steps: a) providing a decorative material comprising a decorative layer and a carrier layer; b) providing a laser; c) introducing different weaknesses by means of the laser into sections of the decorative material for test purposes, wherein the different weaknesses differ from one another in that the different weaknesses are introduced using different parameters of the laser; d) measuring the tear properties of the sections; e) determining the section which has a desired tear property and associating the relevant parameters of the laser with this section; f) setting the laser at the relevant parameters associated in accordance with e); g) introducing weaknesses into the decorative material by means of the laser set in accordance with step f), wherein the laser is not regulated during the introduction of the weakness.

2. Method according to claim 1, characterized in that the decorative layer is made of plastic, preferably PVC, and particularly preferably PUR.

3. Method according to claim 1, characterized in that the carrier layer is a polymer layer, a textile, a nonwoven fabric, a fiber-polymer mixture, a foam material, a natural fiber, a natural fiber mixture, a knitted spacer fabric, or a combination thereof, or it is a thermoplastic or a thermoplastic resin.

4. Method according to claim 1, characterized in that the decorative material is artificial leather or Alcantara.

5. Method according to claim 1, characterized in that the decorative layer is essentially unweakened.

6. Method according to claim 1, characterized in that impact tests, static tensile tests, or, particularly preferably, dynamic impact tensile tests are used to measure the tear properties of the sections in step d). Method according to claim 1, characterized in that the tensile break strength of the decorative material weakened in accordance with step g) is between 20 N/cm2 and 150 N/cm2, particularly preferably between 50 N/cm2 and 100 N/cm2.

8. Method according to claim 1, characterized in that the laser is an unregulated laser.

9. Method according to claim 1, characterized in that the decorative material is not pretreated.

10. Method according to claim 1, characterized in that the weaknesses are blind holes with a diameter of between 0.1 mm and 2.0 mm.

11. Method according to claim 1, characterized in that the weaknesses are blind holes with a diameter of between 0.3 mm and 1.0 mm.

12. Method according to claim 1, characterized in that the weaknesses are blind holes with a diameter of between 0.5 mm and 0.8 mm.

13. Method according to claim 1, characterized in that the depth of the weaknesses corresponds to the thickness of the carrier layer.

14. Method according to claim 1, characterized in that the depth of the weaknesses corresponds to the thickness of the carrier layer multiplied by from 0.8 to 1.2.

15. Method according to claim 1, characterized in that the positioning of the weaknesses in relation to a preferred direction of elasticity of the decorative material is equal both in the sections and according to step g) introduced in the decorative material.

16. Method according to claim 1, characterized in that the progress of the introduction of the weaknesses is not measured during the introduction of the weakness, in particular not by means of a sensor.

17. Method according to claim 1, characterized in that the sections of the decorative material are a region of the same decorative material or from the same batch of the decorative material.

18. Use of a decorative material produced according to claim 1 as an airbag cover in motor vehicles.

19. An airbag cover for a motor vehicle comprising a decorative layer and a carrier layer, and, having a weakness introduced in the carrier layer and not in the decorative layer, the weakness not visible from a visible side of the decorative layer, and, the decorative material tears in a pre-selected manner when the airbag is triggered.

20. The airbag cover of claim 19 wherein the decorative layer is made from an artificial leather and the carrier layer is made from one selected from a thermoplastic polymer or woven textile.

Description

BRIEF SUMMARY OF THE INVENTION

[0078] FIG. 1 a section through the decorative material,

[0079] FIG. 2 a plan view of the rear side of a section of the decorative material, and

[0080] FIG. 3 a section through the weakened decorative material.

[0081] FIG. 1 shows, schematically in section, a decorative material 10 having a lacquer layer 11, a decorative layer 12, thereunder a haptic layer 13, and a carrier layer 14.

[0082] The lacquer layer 11 is transparent, so the design of the visible side 15 is determined by the decorative layer 12.

[0083] The rear side 16 of the decorative material 10 is formed by the carrier layer 14.

[0084] The decorative material 10 provided in accordance with step a) is in this embodiment an artificial leather. The artificial leather comprises a decorative layer 12 made of polyurethane (PUR). The carrier layer 14 is a textile, in this case preferably consisting of cotton fibers or polyester (PES) fibers.

[0085] FIG. 2 shows a plan view of a section 30 of the decorative material 10, specifically of the carrier layer 14 of the decorative material 10, i.e., the rear side 16 of the decorative material 10. In FIG. 2, the section 30 is a rectangular piece of decorative material 10. A test surface 31 is marked on the section 30. The test surface 31 in this embodiment is club-shaped so that its broad ends can be clamped by a material testing machine.

[0086] A solid-state UV laser 20 provided after step b) with a wavelength of 355 mm is set with a parameter or parameter combination in order to, for test purposes, introduce a first weakness 21 into the carrier layer 14 from the rear side 16 and into the section 30. The test weakness 21 is introduced as centrally as possible within the test surface 31.

[0087] The parameters or parameter combinations are then changed and, similar to the first weakness 21, a second, different weakness 21 is introduced into the carrier layer 14 from the rear side 16 and into a second section 30 of the decorative material 10 (not shown).

[0088] In order to test further parameters for the laser 20, further sections 30 are weakened for test purposes (not shown).

[0089] Preferably, the section 30 includes multiple test surfaces 31 which can be weakened in one pass at the set parameters for the laser 20 in order to be able to perform a statistical evaluation with a suitable number of random samples.

[0090] The weaknesses 21 run along the approximate middle of the tapered areas of the test surfaces 31.

[0091] For testing in the material testing machine, the test surfaces 31 are detached, e.g. cut, from the sections 30 and successively clamped by their widened ends in a materials testing machine.

[0092] The individual test surfaces 31 are destroyed by means of an impact tensile test, and the tear energy is determined. The tear properties of the sections 30 having different weaknesses 21 are thus determined.

[0093] Conventionally, the tearing energy that must be applied in order to cause the test surfaces 31 to tear along the weaknesses 21 is between 0.4 joules and 0.9 joules.

[0094] If the desired and pre-selected tear property is then tearing at a tear energy of between 0.4 joules and 0.9 joules, this will then be associated with a corresponding section 30 on the basis of the average values of the measured tear energy of the test surfaces 31. The parameters for the laser 20, by means of which the weaknesses 21 were introduced, are then known for this section 30.

[0095] The impact tensile testing thus determines the parameters for the laser 20 which must be set in order to produce weaknesses 22 in the decorative material 10 such that the decorative material 10 weakened in accordance with step g) has the desired tear properties.

[0096] Once the parameters for the laser 20 have been determined, the laser 20 is permanently set at these parameters. The decorative material 10 is then weakened using the laser 20 in order to obtain, for example, weakened decorative material 10 for airbag coverings.

[0097] As FIG. 3 shows, essentially only the textile carrier layer 14 is weakened, the thickness of which corresponds to approximately half the thickness of the decorative material 10.

[0098] In FIG. 3, the weakness 22 has the shape of a blind hole. The depth of the blind hole corresponds approximately to the thickness of the carrier layer 14.

[0099] The parameters for the laser 20 are selected such that, statistically speaking, the weakness 22 extends almost not at all into the adjoining haptic layer 13 or the decorative layer 12.

[0100] Once the parameters for the laser 20 have been determined for a batch of the decorative material 10, the number of test surfaces 31 or the number of sections 30 can, for example, be reduced when determining the parameters for the laser 20 for a new batch of the decorative material 10 since, once determined, the parameters may not have to be changed, or they may only need to be changed slightly.

[0101] In principle, a whole series of weakened decorative materials 10 can be produced using the method according to the invention, provided that the material properties do not change, for example due to a new batch. To ensure that the weaknesses 22 are properly introduced into the carrier layer 14 of the decorative material 10, random or even periodic sample weaknesses 21 can be introduced into sections 30 of the decorative material 10 for test purposes using the laser 20 set in accordance with step f). The tear property for these sections 30 is verified in accordance with step d). If said property deviates from the desired tear property, steps c) to f) of the method according to the invention are performed once again.