Method for sealing a seam, a composite part and use of same

Abstract

A method for sealing seams of a surface layer containing the seams, the sealing being performed on the side of the surface layer to which a foam layer or adhesive layer is connected in a planar manner. The method further relates to a composite part and the use of same. The method preferably includes a non-contact, planar application of a sealing material onto the seam region along the course of the seam. With the help of the method it is possible to prevent the penetration of the foam or adhesive material in a subsequent processing step and at the same time to eliminate the disadvantages of the existing methods.

Claims

1. A method for sealing a seam (4) of a surface layer (2) containing this seam (4), with two sides (2a and 2b), which is part of a composite part (1), which has at least the surface layer (2) and a polyurethane foam layer or adhesive layer (8) applied in a planar manner on one of the sides (2a or 2b) of the surface layer, comprising the following method steps: i) spraying or casting of a sealing material (3) onto a planar application region on the side of the surface layer (2) to which the polyurethane foam layer or adhesive layer (8) is connected, wherein the edge of the planar application region surrounds the seam (4), ii) hardening and adhering of the sprayed on or cast sealing material (3), iii) applying the polyurethane foam layer (8) onto the side of the surface layer (2) on which the hardened sealing material (3) is situated, wherein the sealing material (3) is a fluid reactive mixture based on polyurethane.

2. The method according to claim 1, wherein the method has the following method steps: i) spraying or casting a sealing material (3), which has a temperature of 20 to 90 C., onto a planar application region on the side of the surface layer (2) to which the polyurethane foam layer or adhesive layer (8) is connected, wherein the edge of the planar application region surrounds the seam (4), ii) hardening and adhering of the sprayed on or cast sealing material (3) at temperatures of 20 to 90 C., within 5 seconds to 5 minutes, iii) applying the polyurethane foam layer (8) onto the side of the surface layer (2) on which the hardened sealing material (3) is situated.

3. The method according to claim 1, wherein the sealing material (3) is applied in a contactless manner via a spraying- or casting method onto the side of the surface layer (2) to which the polyurethane foam layer or adhesive layer (8) is connected.

4. The method according to claim 1, wherein the fluid polyurethane-based reactive mixture contains the following components: a) at least one organic polyisocyanate selected from the group consisting of polyisocyanates based on diphenylmethane diisocyanate and/or polyphenylpolymethylene polyisocyanate and modified organic polyisocyanates based on diphenylmethane diisocyanate, b) at least one polyol with a number average molecular weight of 300 to 15000 g/mol, selected from the group consisting of polyether polyols, polyester polyols, polycarbonate diols and polyethercarbonate polyols, c) if applicable chain extenders and/or cross-linking agents with number average molecular weights of 62 to <300 g/mol, d) catalysts e) if applicable adjuvants and/or additives.

5. The method according to claim 1, wherein the surface layer (2) consists of a thermoplastic plastic.

6. The method according to claim 1, wherein the surface layer (2) consists of a thermosetting plastic.

7. The method according to claim 1, wherein the surface layer (2) consists of an elastomer plastic.

8. The method according to claim 1, wherein the surface layer (2) consists of a natural material.

9. The method according to claim 1, wherein the surface layer (2) consists of a synthetic textile, woven or non-woven material.

10. The method according to claim 1, wherein the surface layer (2) consists of a natural textile, woven or non-woven material.

11. The method according to claim 1, wherein the polyurethane foam (8) is formed by spraying-on a corresponding polyurethane reaction mixture onto the side of the surface layer (2) on which the sealing material (3) is situated.

12. The method according to claim 1, wherein the seam (4) is sewn with a thread which requires the piercing of the surface layer in a sewing method.

13. The method according to claim 1, wherein the thread of the seam (4) is embedded into the material of the surface layer in such a way that the thread has contact with the foam material or with the adhesive.

14. A composite part (1) consisting of a) a seam (4) b) a surface layer (2), containing this seam (4), with two sides (2a and 2b) c) a polyurethane foam layer or adhesive layer (8) applied in a planar manner on one of the sides (2a or 2b) of the surface layer (2) d) a planar application region of a sealing material (3) of a fluid reactive mixture based on polyurethane on the side of the surface layer (2) to which the polyurethane foam layer or adhesive layer (8) is connected, wherein the edge of the planar application region surrounds the decorative seam (4).

15. Use of the composite part (1) according to claim 14 for the production of instrument panels, armrests, door side trims, centre consoles and covers for glove compartments.

Description

[0058] FIG. 1 shows a surface layer 2 in cross-section with a decorative seam. This decorative seam is a seam which is intended to convey the impression of two surface layers which are sewn to one another, but which does not physically contain any separation. The surface layer 2 has two decorative seams 4 with respectively a puncture 5. Between the two decorative seams 4, running substantially parallel to one another, an indentation 7 runs on a visible side 2a, which is intended to convey the impression that at this location two e.g. surface layers are sewn to one another (in the style of leatherworking). In order to provide a sealing of the decorative seams 4 for the back-foaming or planar bonding of the surface layer 2, the region between the two seam courses 4 and over the seam courses on the side 2b of the surface layer 2 which is to be foamed or is to be wetted with adhesive, is covered with sealing material 3. The punctures 5 of the two seams 4 are sufficiently covered by the sealing material 3 here so that it can be ruled out that the seam courses are reached by the back-foaming material or the adhesive material.

[0059] FIG. 2 shows a modification of FIG. 1. In this illustration, the use with an actual joining location 7a of the surface layer 2 is shown in cross-section.

[0060] FIG. 3 shows a further modification of FIGS. 1 and 2. In this illustration, the use in a single seam course 4 is illustrated without a second seam 4, running parallel, and without an indentation 7.

EXAMPLE

[0061] Starting Compounds: [0062] Polyol A: polyalkylene oxide based on glycerin as starter and propylene oxide with 18% terminal ethylene oxide block; OH-number 35 mg KOH/g polyol [0063] Polyol B: polyalkylene oxide based on propylene glycol as starter and propylene oxide with 29% terminal ethylene oxide block; OH number 28 mg KOH/g polyol [0064] Chain extender A: diethylene glycol [0065] Chain extender B: 1,4 butanediol [0066] Catalyst A: Dabco@NE1060 of the company Evonik, Essen [0067] Catalyst B: FOMREZ UL-28 of the company Momentive Performance Materials [0068] Adjuvant A: Irganox 1135 of the company BASF [0069] Isocyanate: Desmodur PC-N of Covestro Deutschland AG; [0070] diphenylmethane diisocyanate/polyphenylmethane polyisocyanate mixture of the company Covestro Deutschland AG with an NCO content of 26.0% by weight; viscosity at 25 C. of 120 mPa*s

[0071] Test Description:

[0072] The production took place in a heatable mould with a mould temperature of 25 C. The temperature of the polyol component (components b) to e)) was 70 C. and the temperature of the isocyanate component a) was 65 C. The components were mixed in the mixing head at a pressure of 130 bar (polyol component) or respectively 110 bar (isocyanate component) and sprayed on with decorative seam via an air-protected spray head onto an application region, surrounding the decorative seam, of the moulded skin present in the mould.

[0073] After a 2-minute hardening, in a further step a polyurethane foam layer was produced on the side of the moulded skin on which the hardened sealing material is situated. For this, a polyurethane reactive mixture consisting of the polyol component Bayfill 531F40 of Covestro Deutschland AG and the isocyanate Desmodur581F07 of Covestro Deutschland AG were applied onto the moulded skin with the sealed decorative seam via a high pressure mixing head in a heated mould at 42 C. and the mould was tightly closed. After 90 seconds at 42 C. the mould was opened and the composite element was removed. The tightness of the seal was checked visually.

[0074] Table: Composition of the polyurethane reactive mixture for the sealing of the seam

TABLE-US-00001 Component Polyol A [Parts by weight] 42.35 Polyol B [Parts by weight] 44.05 Chain extender A [Parts by weight] 2.00 Chain extender B [Parts by weight] 11.00 Catalyst A [Parts by weight] 0.08 Catalyst B [Parts by weight] 0.02 Adjuvant A [Parts by weight] 0.5 Isocyanate [Parts by weight] 53 Result: no passage of the foam through the holes of the seam and no damage to the seam or to the thread