SURFACE COATING FOR AN EXTERIOR TRIM PART

Abstract

An exterior trim part comprising at least a fibrous layer forming the carrier, characterized in that at least one surface consists of a splat polymer coating deposited at least along a portion of the surface forming a splat polymer coating layer.

Claims

1. An exterior trim part comprising at least a fibrous layer forming the carrier, wherein at least one surface consists of a splat polymer coating deposited at least along a portion of the surface forming a splat polymer coating layer.

2. The exterior trim part of claim 1, whereby the splat polymer coating has shore hardness at room temperature below shore 50D, preferably a hardness below shore 70A.

3. The exterior trim part of claim 1, whereby the splat polymer coating is a thermoplastic polymer, or a mixture of at least two thermoplastic polymers, preferably at least one polymer of the group of polyolefins such as linear density polyethylene (LDPE) or polypropylene (PP), ethylene-vinyl acetate (EVA), polyester (PES) or copolymer of polyester (CoPes), thermoplastic elastomers (TPE), such as thermoplastic polyurethane (TPU) or thermoplastic polyester elastomer (TPE-E) or thermoplastic polyolefin (TPO).

4. The exterior trim part of claim 3, whereby the polymer further comprises at least one additive of the groups of flame retarders, stabilizers, anti-oxidants, colour agents or pigments, like carbon black, Titanium dioxide, calcium carbonate, Calcium sulphate, Silicon dioxide, aluminium oxide or organic colouring molecules or polyphosphates.

5. The exterior trim part of claim 1, whereby each polymer of the splat coating has a melt flow index at about 190 C. above about 20.

6. The exterior trim part of claim 1, whereby at least one splat polymer coating layers is air permeable, preferably the air flow resistance over the carrier layer including the splat coating layer or layers is between about 100 and about 8000 N.Math.s.Math.m-3.

7. The exterior trim part of claim 1, whereby the fibrous layer comprises fibers or endless filaments and a thermoplastic binder.

8. The exterior trim part of claim 7, whereby the fibers or endless filaments are at least one of mineral fibers, preferably glass fibers, thermoplastic fibers, preferably polyester, like polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), or natural fibers, like cotton.

9. The exterior trim part of claim 7, whereby the binder is at least one of a copolymer of polyester, polyolefin, like polypropylene or polyethylene, polyamide.

10. The exterior trim part of claim 1, whereby the fibrous layer consists of polyester bi-component endless filaments with a core-sheath structure, and whereby the sheath material is a copolymer of polyester forming the binder for the fibrous layer.

11. The exterior trim part of claim 1, further comprising at least one additional layer on the surface of the carrier opposite the coated surface, preferably one of a scrim, film or additional noise absorbing layer like a foam or felt.

12. The exterior trim part of claim 1, further comprising a scrim layer, like a nonwoven, woven or knit layer, between the fibrous carrier layer and the deposited splat coating layer.

13. The exterior trim part of claim 1, whereby the splat coating layer has an area weight of between about 50 and about 500 g.Math.m-2.

14. A method of using the exterior trim part with the splat coating according to claim 1 for a vehicle as an underbody panel, an outer wheel arch liner, an under engine shield, an aerodynamic panel, a cover or panel for the engine or gearing, a rocker panel, or a diffuser panel.

15. A method of producing an exterior trim part comprising at least the steps of forming and moulding a fibrous carrier in an exterior trim part and coating at least partially at least one surface using thermal polymer spray to splat molten droplets on the carrier surface forming a layer integrally bonded to the carrier surface.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] FIG. 1 is a schematic drawing of an outer wheel arch liner according to the state of the art.

[0049] FIG. 2 is a schematic drawing of the a polymer spray technology

[0050] FIG. 3 is a schematic drawing of the spray direction on the outer wheel arch liner.

[0051] FIG. 4 shows a vehicle from underneath.

[0052] FIG. 5 shows an example of a set of different exterior panels.

[0053] FIG. 6 shows a microscopic view of a surface thermal spray coating.

DETAILED DESCRIPTION

[0054] FIG. 1 shows an arched shaped wheel arch liner that can be placed in the wheel well of a vehicle opposite the wheel tread (not shown). Depending on the front or the rear wheel and left or right side of the car and on the design of the car, the wheel arch liner might be slightly different formed. A first surface 1 is facing towards the car body, while a second surface 2 is facing towards the wheel tread. Both surfaces might be treated with a coating according to the invention. However surface 2 is more prone to icing, soiling and or stone chipping and is therefore preferably at least partially coated according to the invention.

[0055] FIG. 2 shows schematically an example of a polymer thermal spray process to deposit the splat polymer coating on the fibrous substrate.

[0056] In a first step of the process a thermal fluid spray gun is producing a stream of hot air or fluid 3, in which a feedstock 4 of polymer particles is fed. These particles can originate from a polymer powder or a pressure exploded polymer melt 4. All feed and airflow functions are preferably combined in one spray gun head. Due to the interaction of the temperature on the polymer particles they are accelerated and molten to form liquid or partially-liquid droplets in the powder spray embodiment 5, 6. In the molten spray process, the molten particles are accelerated towards the substrate using the hot air or fluid 3. These droplets are colliding with the substrate face layer and form splats 7flattened solidified droplets or fibers, eventually leggingthat partly fuse and or interlock with neighbouring splats as well as with the fibers or filaments on the surface of the carrier layer 2, forming an irregular coating on the surface of the carrier layer. Surprisingly the splats form fusion bonds as well as mechanical interlocking bond with the carrier layer, causing a preferred strong bond between the carrier layer and the coat that cannot be easily broken again.

[0057] The shown process is just an example; other processes known in the art to produce a similar coating according to the invention may be used as well.

[0058] FIG. 3 shows a moulded outer wheel arch liner 1 ready to get a coat. The arrows 2 indicate a possible direction of the sprayed coating at the inner side of the arched wheel arch liner. In this case the wheel arch liner contains a fold line 9 to make the inner side of the wheel arch liner more accessible for the spray coating process.

[0059] It is not necessary that the complete surface of the inner side of the outer wheel arch liner is coated, for instance the outer areas that are facing the side of the tire when placed in the car might not need a coating, while the areas close to the road (indicated with A) might need a thicker coat, as icing might be building up in these areas quicker and more pronounced as in the middle areas (indicated with B) where a lower air flow resistance might be more beneficial for the overall acoustic attenuation. Preferably also the outer surface in zone A, in particularly the area closer to the front of the car, might be coated with a thicker coat to prevent stone chipping damage from stones flipping over the rim hitting the back surface (indicated with 2 in FIG. 1) in this lower area.

[0060] In areas more prone to stone chipping the coating layer might be thicker, for instance in zone A.

[0061] Preferably the spray coating process is done with help of an automated process, preferably a robotic arm, ensuring an even distance to the surface layer and an even layering of the droplets on the surface.

[0062] Preferably the surface is coated directly after the moulding without a substantially cooling of the part. In this way the heat of the moulding still available in the part can be used to further optimise the coating process. If the difference between the temperature of the surface and the temperature of the droplets would be too large, the droplets would be solidified upon the impact and would not form a good fusion and or bond with neighbouring splats or with the fibrous carrier layer. The coating would become grainy and might not bind to the surface. Alternatively the spray coating can be done in a well-tempered room or onto a heated substrate.

[0063] FIG. 4 shows the underside of a vehicle with examples of under body panels 10, 11 mounted to the chassis 12 of the vehicle, for instance to the cross beams of the steel carrying body of a vehicle. The panel 10 in front, also known as under engine panel is the most exposed to the forces during driving or for instance driving through fresh snow.

[0064] FIG. 5 shows additional under body panels and a layout for such panelling, with the front or under engine panel 16, the main under body panel 13, in this case divided in 2 parts, a centre panel 14 and the back panel 15, situated under the boot or trunk of the vehicle.

[0065] All these panels for the underside of the vehicle might be designed according to the invention, and may benefit from a partial or full thermal spray coating.

[0066] FIG. 6 shows a microscopic view of a surface thermal spray coating according to the invention with a splat polymer coating deposited on the surface, forming an air permeable layer. The surface coating shows areas where an irregular pattern of the splats are formed and solidified 18, while in other areas 17 the fibrous carrier layer can still be seen in uncoated spots. Considering the size of these uncoated spots this will cause the air flow resistance necessary to obtain a good sound attenuation.