METHOD FOR PRODUCING A PLASTIC VEHICLE ATTACHMENT PART

Abstract

A method for producing a polymeric vehicle attachment part with a decorative element is obtained when a polymeric attachment part is prepared, a decorative element is transferred from a carrier film onto a first surface of the attachment part by hot stamping using a stamp, and at least the first surface is provided with a protective coating.

Claims

1-15. (canceled)

16. A method for producing a polymeric vehicle attachment part with a decorative element, comprising the steps of a. preparing a polymeric attachment part, b. transferring a decorative element from a carrier film onto a first surface of the attachment part by hot stamping using a stamp, and c. providing a protective coating on at least the first surface.

17. The method according to claim 16, wherein step (b) further comprises: arranging the carrier film with the decorative element such that the decorative element faces the attachment part, acting the stamp on the surface of the carrier film facing away from the decorative element such that the decorative element is pressed against the first surface, and detaching the carrier film, wherein the decorative element remains on the first surface.

18. The method according to claim 16, wherein the protective coating comprises thermally curing or UV curing coatings.

19. The method according to claim 18, wherein the protective coating comprises polysiloxanes, polyacrylates, polymethyacrylates, polyurethanes, or mixtures or copolymers thereof.

20. The method according to claim 16, wherein the decorative element includes at least one decorative layer and at least one adhesive layer.

21. The method according to claim 20, wherein the decorative element further comprises a protective layer such that the decorative layer is arranged between the protective layer and the adhesive layer.

22. The method according to claim 16, wherein the thickness of the decorative element is less than or equal to 100 μm.

23. The method according to claim 22, where in the thickness of the decorative element is between 2 μm to 20 μm.

24. The method according to claim 16, wherein a separating layer is arranged between the carrier film and the decorative element.

25. The method according to claim 16, wherein, process step (b) further comprises setting the stamp to a temperature between 120° C. to 250° C.

26. The method according to claim 25, wherein the temperature is between 140° C. to 200° C.

27. The method according to claim 16, wherein the stamp acts with a pressure of 15 kg/cm.sup.2 to 50 kg/cm.sup.2 on the first surface with a duration of action of at least 1 second.

28. The method according to claim 27, wherein the pressure is 20 kg/cm.sup.2 to 40 kg/cm.sup.2.

29. The method according to claim 27, wherein the pressure is 25 kg/cm.sup.2 to 35 kg/cm.sup.2.

30. The method according to claim 27, wherein the duration of action is 2 to 4 seconds.

31. The method according to claim 16, wherein the step c) of providing the protective coating comprises flow coating.

32. The method according to claim 16, wherein the attachment part contains polycarbonate (PC), polymethylmethacrylate (PMMA), styrene acrylonitrile (SAN), acrylonitrile styrene acrylester (ASA), polyethylene terephthalate (PET), or copolymers or mixtures thereof.

33. The method according to claim 16, wherein the attachment part has a thickness between 1 mm and 20 mm.

34. The method according to claim 31, wherein the attachment part has a thickness between 2 mm and 10 mm.

35. The method according to claim 16, wherein the adhesive layer comprises an acrylic-based adhesive.

36. A polymeric vehicle attachment part with a decorative element, comprising: a polymeric attachment part, a decorative element applied onto a first surface of the attachment part by hot stamping, and a protective coating at least on the first surface with the decorative element.

37. A method of using a polymeric vehicle attachment part according to claim 36 as an exterior attachment part for motor vehicles, comprising applying the polymeric vehicle attachment part to a vehicle window, pillar cover, luminaire cover, radiator grill panel, or spoiler.

Description

[0049] The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are a schematic representation and not true to scale. The drawings in no way restrict the invention.

[0050] They depict:

[0051] FIG. 1 a cross-section of a polymeric attachment part during the method according to the invention,

[0052] FIG. 2 a cross-section through one embodiment of a carrier film with a decorative element,

[0053] FIG. 3 a cross-section through one embodiment of the polymeric attachment part with a decorative element according to the invention, and

[0054] FIG. 4 an exemplary embodiment of the method according to the invention with reference to a flowchart.

[0055] FIG. 1 depicts a cross-section of a polymeric attachment part at different times in the method according to the invention: (a) before hot stamping, (b) during hot stamping, (c) after hot stamping, and (d) after application of the protective coating. The polymeric attachment part 1 is, for example, a plastic window for a motor vehicle, for example, a rear side window pane. The polymeric attachment part 1 can, however, also be another external attachment part of a motor vehicle, for example, a pillar cover, a spoiler, or a luminaire cover. The polymeric attachment part 1 is made, for example, of polycarbonate and has a thickness of 4 cm. The window pane, which, in reality, typically consists of two material phases or material components, namely, a transparent material phase comprising the entire surface and an opaque component applied thereon peripherally in the edge region, is depicted homogeneously in the figure for the sake of simplicity. The method according to the invention can also be performed at any location of the attachment part 1, i.e., both in transparent and opaque regions such that the precise structure of the attachment part 1 is not significant.

[0056] The attachment part 1 is positioned under a stamp 4 (FIG. 1(a)), with the first surface (I) of the attachment part, which is later provided as the outside surface in the installed position, facing the stamp 4. A decorative element 2 on a carrier film 5 is positioned between the stamp 4 and the attachment part 1. The carrier film 5 is a flat film with a plurality of decorative elements 2 that is rolled onto two rollers (not shown). Thus, the carrier film 5 can be transported farther such that another decorative element 2 is conveyed under the stamp 4 and is provided for application on another attachment part 1.

[0057] The decorative element 2 is implemented as a multilayer film, which will be described more precisely in the following. For the sake of better understanding, the various decorative elements 2 are depicted as discrete elements on the carrier film 5. Typically, in reality, the multilayer film will cover the carrier film substantially over its entire surface, with the individual decorative elements 2 being detached from the overall film by adhesive action on attachment part 1. This detachment can also be facilitated by incisions or perforations in the overall film.

[0058] The stamp 4 acts on the surface of the carrier film 5 facing away from the decorative element 2 such that the decorative element 2 is pressed onto the first surface (I) of the attachment part 1 (FIG. 1(b)), for example, with a pressure of 30 kg/cm.sup.2. The stamp 4 has a temperature of, for example, roughly 160° C. The duration of action of the stamp 4 on the surface (I) of the attachment part 1 is, for example, 2.5 s. The action of the stamp 4 is typically accomplished by its lowering onto the attachment part 1, but can also be accomplished, alternatively or additionally, by raising the attachment part 1 toward the stamp 4.

[0059] Then, the stamp 4 and the attachment part 1 are again separated from one another and the carrier film 5 is detached, with the decorative element 2 remaining on the surface (I) of the attachment part 1 (FIG. 1(c)).

[0060] Then, the attachment part 1 with the decorative element 2 is provided with a protective coating 3 (FIG. 1(d)), which is implemented, for example, in two layers, and comprises an acrylic-based primer and a polysiloxane-based hardcoat applied thereon.

[0061] Because of the fact that the decorative element 2 is applied on the outer surface (I) of the attachment part 1, it is always readily discernible later in the installed position, even when the attachment part has low or no light transmittance. This is a major advantage compared to some conventional decorative elements introduced by film insert molding, which are arranged behind the attachment part or at least a component of the attachment part) in the direction of vision. Nevertheless, the decorative element 2 is protected by the protective coating 3 against mechanical damage, as a result of which the hot stamping technique can be used for external parts and also complies with the high stability requirements for motor vehicle parts (Rigid Plastic Glazings, ECE R43 Appendix 14, Class /M). This finding was unexpected and surprising for the person skilled in the art.

[0062] FIG. 2 depicts by way of example the structure of a suitable carrier film 5 with a decorative element 2. The carrier film is made of PET and has a thickness of 20 μm. The decorative element 2 consists of three layers, namely, with increasing distance from the carrier film: a protective layer 2a, a decorative layer 2b, and an adhesive layer 2c. The decorative element 2 makes contact with the attachment part 1 via the adhesive layer 2c. The adhesive layer 2c effects strong adhesion between the decorative element 2 and the attachment part 1. The adhesive layer 2c is, for example, a layer of an acrylic-based adhesive with a thickness of 1.0 μm. The decorative layer 2b effects the actual visual impression of the decorative element 2. The decorative layer 2b is, for example, a layer with a thickness of 5.0 μm based on polyacrylate, which is colored by embedded or printed-on pigments or dyes in the form of the desired decoration. The protective layer 2a is, for example, an acrylic-based polymeric layer with a thickness of 1.0 μm. The protective layer protects the decorative layer against mechanical damage when the decorative element 2 is applied on the attachment part 1.

[0063] A separating layer 6 that promotes the detachment of the decorative element 2 from the carrier film 5 is arranged between the carrier film 5 and the decorative element 2. The separating layer has, for example, a thickness of 0.5 μm.

[0064] FIG. 3 depicts a cross-section through an attachment part 1 according to the invention with a decorative element 2. The attachment part 1 consists of a transparent material phase 1a and an opaque material phase 1b. Such a structure occurs, for example, in the edge region of windowpanes or over the whole surface in pillar covers. In the latter case, the transparent phase produces a glasslike effect with a depth effect on the surface of the opaque phase, which is very appealing visually. The transparent material phase 1a is made, for example, from polycarbonate (PC) and has a thickness of 4 mm. The opaque material phase 1b is made, for example, from a PC/ABS mixture and has a thickness of 2.5 mm. The transparent material phase 1a, which is to face the external environment in the installation position, can be clear and colorless, but can also be tinted or colored, as is the case, for example, with privacy glazings. Nevertheless, the decorative element 2 is readily discernible on the outer surface (I).

[0065] The attachment part 1 with the decorative element 2 is provided with a protective coating 3, by which means the attachment part 1 and in particular the decorative element 2 as well are protected against mechanical damage. Without the protective coating 3, the decorative element 2 would be too susceptible to abrasion, as a result of which use of the attachment part 1 as an external attachment part, i.e., in the exterior of the vehicle, would be ruled out. The protective coating 3 and the protective layer 2a of the decorative element 2 are preferably coordinated with one another. If the decorative element 2 of FIG. 2 is used with the acrylic-based protective layer 2a, an acrylic-based primer in combination with a polysiloxane hardcoat is preferably used as the protective coating 3. Thus, the adhesion of the protective layer 3 on the decorative element 2 is advantageously influenced.

[0066] The protective coating also includes UV blockers, by means of which the decorative element 2 is protected against fading due to UV irradiation.

[0067] The thickness of the protective layer 3 is, for example, roughly 20 μm. The thickness of the protective layer 3 can be constant over the entire attachment part. However, the thickness of the protective layer 3 can also be—as depicted schematically in the figure—somewhat thinner in the region of the decorative element 2 such that the total thickness of the protective coating 3 and the decorative element 2 is approx. equal to the thickness of the protective coating 3 in the regions of the first surface (I) without the decorative element 2. Thus, a homogeneous surface without disruptive bumps is created.

[0068] FIG. 4 depicts a flowchart of an exemplary embodiment of the method according to the invention for producing a polymeric vehicle attachment part with a decorative element.

[0069] The strength of the adhesive bond of attachment parts with a decorative element produced according to the invention was determined using test procedures per DIN EN ISO 2409 as well as test procedures, as are required by many auto manufacturers, for example, H.sub.2O high-pressure spraying. Scratch or abrasion resistance was tested using the Crock meter test and processing with brushes of a carwash. Here, the layer structure proved to be adequately stable in terms of adhesion, abrasion resistance, and scratch resistance to be used on the outer surface of an external vehicle attachment part. Moreover, UV resistance was tested by intensive UV irradiation. No radiation-induced degradation, such as color shifting, yellowing, fading, micro-fissures, or delamination were observed.

[0070] It was unexpected and surprising for the person skilled in the art that a decorative element applied by hot stamping can be used on the external surface of a motor vehicle attachment part. Until now, it was assumed that no adequate abrasion resistance and mechanical resistance can be ensured.

LIST OF REFERENCE CHARACTERS

[0071] (1) polymeric vehicle attachment part

[0072] (1a) transparent material phase of 1

[0073] (1b) opaque material phase of 1

[0074] (2) decorative element

[0075] (2a) protective layer of 2

[0076] (2b) decorative layer of 2

[0077] (2c) adhesive layer of 2

[0078] (3) protective coating

[0079] (4) stamp

[0080] (5) carrier film

[0081] (6) separating layer

[0082] (I) first surface of 1