Dual finish veneer and lacquer system

Abstract

Different finishes are applied to lower and upper layers. A heat activated adhesive film is applied to the lower surface of the upper veneer. The upper veneer and adhesive is selectively perforated

Description

Introduction The present invention relates to a method of forming a dual finish on an interior part for an automobile, and to interior parts for an automobile comprising a dual finish, comprising a lower layer having a first finish and an upper veneer layer having a second finish, wherein the upper veneer layer is perforated to reveal sections of the lower layer. Background It is desirable to add an aesthetically pleasing decorative finish to interior parts for an automobile. In some instances a dual finish is desirable, in which an upper and lower layer have contrasting finishes, with the parts of the lower layer being visible though one or more perforations or openings in the upper layer. Accordingly, a method of forming a dual finish on an interior part for an automobile is desired. It is known to apply a veneer to such automobile interior parts. However, applying a contrasting finish to an upper veneer layer and to a lower layer poses a particular challenge. Such challenges are particularly apparent if the lower layer is to have a high gloss, polished finish and the upper veneer layer is to have a matte finish. Application of a dual finish is not possible after the veneer has been applied to the lower surface as to create a high gloss finish on the lower layer requires polishing the lower layer without polishing the matte veneer. However, tools typically used for polishing high gloss surfaces have dimensions that greatly exceed the dimensions of the perforations or openings created in the upper veneer layer. Standard polishing mops are typically greater than 30cm in diameter and even small mops for detailed work are at least 10-15mm in diameter. Accordingly, it is not possible to polish the lower layer without also undesirably polishing the overlying matte veneer layer. Conversely, it is not possible to apply a matte finish to the upper veneer layer after it has been applied to the lower layer without also applying the matte finish to the lower layer. Inevitably, application of one finish to one of the layers contaminates or damages the contrasting finish on the other layer, resulting in unacceptable final product. Another known option is to finish the upper and lower layers separately and then to assemble the final part by gluing the upper veneer layer to the lower layer. However, this approach also yields unsatisfactory results as a result of glue bleed. On assembly using conventional glues, e.g. liquid glues, some glue inevitably flows into the exposed parts of the lower surface, damaging the high gloss finish. As noted above, this cannot be remedied after assembly, e.g. by incorporating a subsequent polishing step, without undesirably polishing the matte veneer layer. Accordingly, a method of forming a dual finish on an interior part for an automobile is required, without the problems noted above. It is a further aim of the invention to provide an interior part for an automobile having a dual finish. Summary of the Invention The invention provides a method of forming a dual finish on an interior part for an automobile comprising: a) providing a lower layer and applying a first finish to the lower layer; b) providing an upper veneer layer and applying a second finish to the upper veneer layer, wherein the second finish is different to the first finish; c) pre-applying a heat-activated adhesive film to a lower surface of the upper veneer layer; d) selectively removing sections of the upper veneer layer and heat-activated adhesive film by laser cutting to provide a perforated layer; e) applying the upper veneer layer to the lower layer and applying heat and / or pressure to cure the heat-activated adhesive film. The lower layer may be made of any material suitable for use in automobile interior trims that is capable of receiving a high gloss finish. Typically, the lower layer can be made of metal, wood, stone or other materials, optionally painted or with additional decorative elements applied such as shell (for example mother of pearl), or metal leaf (for example gold leaf, silver leaf, copper leaf or other decorative metal leaf). The first finish is typically a high gloss lacquer, which may be applied using conventional methods known in the automobile industry. The upper veneer layer may be made of any suitable material, such as wood, leather or fabric. The upper veneer layer is finished such that it has a contrasting visual effect to the finish applied to the lower layer. Typically, the second finish is an open pore matte lacquer, which may be applied using conventional methods known in the automobile industry. The heat-activated adhesive film is preferably a polymeric film that forms a temporary bond when placed in contact with the upper veneer layer and forms a permanent bond between the upper and lower layers when subjected to a curing process. For example, the temporary bond may be formed at a temperature of 20-50°C, for example at 20°C, 30°C, 40°C or 50°C. The permanent bond may be formed by carrying out the curing process at a temperature of 75-110°C and a pressure of 5-20 N / cm2 The curing temperature can be varied according to the manufacturer’s specifications for the heat-activated adhesive film, and to optimise adhesion without damaging the finish of the lower and upper veneer layers or inducing glue bleed. Typically, the curing step is carried out at 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C or 110°C. Suitable heat-activated adhesive films are available commercially, for example the Flexel™ range of products manufactured by H.B. Fuller. Such heat-activated adhesive films typically are polyurethane-based products provided as a sheet having a thickness of between 25-100 pm, for example 25 pm, 50 pm, 75 pm or 100 pm, and exhibiting high fracture toughness, peel and shear strength, while maintaining flexibility. Such adhesives provide a significant advantage in the context of the present invention in that they are less prone to glue bleed, and hence the lower layer and upper veneer layer can be joined without contamination of either the first finish or the second finish. A further advantage is that the heat-activated adhesive film can conveniently be cut using a laser at the same time as the upper veneer layer. This ensures that the perforations in the upper veneer layer and the heat-activated adhesive film are congruent and avoids the need to align the layers after separate cutting of the veneer and the heat-activated adhesive film. Pressure may be applied during the pre-tacking, temporary bond formation step and during the curing step using a membrane press. A membrane press is conventional in the art, and an example of a suitable membrane press can be obtained from Global Vacuum Presses®. The skilled person can determine suitable times for the pre-tacking step and the curing step. For example, the pre-tacking step may be carried out for a duration of approximately one minute, approximately two minutes, approximately 5 minute or approximately 10 minutes. The curing step may be carried out for a duration in line with the manufacturer’s recommendations. Curing times as low as 30-90 seconds may be appropriate in some instances. In other instances a longer curing time is preferred, for example 30 minutes, 60 minutes, 90 minutes, 120 minutes of longer. In preferred embodiments, a 120 minute curing time is used. In other embodiments, a curing time from 40 to 100 minutes can be used. In preferred embodiments step a) of the method comprises: 1) providing a lower layer; 2) applying a prime foil substrate, 3) applying a sealer layer; 4) optionally applying a paint layer; 5) optionally applying a further sealer or lacquer layer; 6) curing the sealer or lacquer layer; and 7) sanding and polishing the finished lower layer. Such methods are known to the skilled person. For example, the prime foil substrate is known to provide a base layer that provides a good substrate for subsequent layers. Typically a sealer layer, or multiple sealer layers, are then applied to protect the lower layer, e.g. from water and / or UV damage. Typically, the sealer is applied as a continuous layer over the entire surface of the lower layer, for example using a spray gun. Typically, the sealant is a polyurethane-based sealant. Suitable sealants can be obtained from Votteler®. If the lower layer is to be painted, one or more paint layers can then be applied. Any suitable automotive paint can be used, for example a polyurethane-based paint. Again, the paint layer or layers are typically applied using a spray gun. Optionally, further sealer or lacquer layers are then applied, for example to protect the paint layer if present. Typically, one or more layers of a high gloss lacquer, for example a polyester-based or polyurethane-based lacquer, are applied using a spray gun using conventional materials and techniques. The lacquer may then be cured, for example by placing in an oven at approximately 80°C for 2 hours before final sanding and polishing to achieve the final high gloss finish. In some embodiments, the lower layer is additionally finished with a metal leaf. In such embodiments, the following the additional steps may be present: 8) cleaning the finished lower layer; 9) applying a metal leaf size to the lower layer; 10) applying a metal leaf to the prepared surface; 11) applying a further sealer or lacquer layer, 12) curing the sealer or lacquer layer; and 13) sanding and polishing the finished lower layer. The cleaning step ensures a grease-free, clean surface for application of the subsequent layers, first of a suitable size layer to which the metal leaf can adhere, then the metal leaf itself. Standard gilding techniques are typically used. After application of the metal leaf, a sealer or lacquer layer is applied, cured and sanded and polished as described above to protect the metal leaf and to provide a high gloss finish. Similar methods are used for preparing the upper veneer layer. Accordingly, in preferred embodiments step b) comprises: 1) providing an upper veneer layer; 2) optionally removably fixing the veneer layer to a support; 3) sanding the veneer layer; 4) applying a sealer layer; 5) optionally sanding the sealer layer; and 6) applying an open pore lacquer layer. Use of support, such as an MDF backing board is preferred to prevent damage to the upper veneer layer during the initial sanding step and during subsequent processing. Typically the upper veneer layer is taped to an MDF backing board prior to carrying out steps 1-5 above, and then removed from the backing board after these steps have been completed. The sealer layer, and its application, are typically as described above for step a) of the method. The use of an open pore lacquer in step 6) above provides a matte finish to the upper veneer layer. Suitable open-pore lacquers are known such as polyurethane-based open pore lacquers. Typically only a single layer of open pore lacquer is used of negligible thickness. This allows the texture of the veneer to be felt through the lacquer. In preferred embodiments step c) is carried out at a temperature of 20-50°C. This allows the heat-activated adhesive film to bond loosely to the upper veneer layer and allows the laser cutting of step d) to be carried out on both the upper veneer layer and the heat-activated adhesive film simultaneously. In step d), the selective removal of sections of the upper veneer layer and heat-activated adhesive film by laser cutting to provide a perforated layer may be used to create any desired pattern, including geometric, abstract or figurative patterns made up of one or more apertures of any appropriate size. Use of laser cutting enables very precise sections of the upper veneer layer and heat-activated adhesive film to be removed. In some embodiments, the sections removed may only be a few millimetres in one or more linear dimensions, or even less than one millimetre. Reference to perforation or perforations according to the invention includes any intentional removal of sections of the upper veneer layer. The perforations include but are not limited to discrete holes or series of holes. Rather, reference to perforations encompasses decorative openings including holes of substantially circular or oval form, holes of substantially square or rectangular form, channels arranged either as a series of substantially parallel lines or in an intersecting pattern, whether linear or curved, or other decorative abstract or figurative shapes. The perforations may be entirely contained within the upper veneer layer, i.e. internal perforations, or may abut one or more edges of the upper veneer layer. In preferred embodiments step e) is carried out at a temperature of 75-110°C and a pressure of 5-20 N / cm2 This step is typically carried out using a membrane press. As described above, a membrane press is conventional in the art, and an example of a suitable membrane press can be obtained from Global Vacuum Presses®. The interior part may be any suitable interior part of an automobile, for example any part to which an upper veneer layer can be applied. For example, the interior part may be selected from the list comprising a dashboard, a door panel, a centre console, a footplate, an armrest, a boot floor, a seat back and individual panels or sections thereof. The invention also provides a method of forming a dual finish on an interior part for an automobile comprising: 1) providing a lower layer; 2) applying a prime foil substrate to the lower layer, 3) applying a sealer layer to the lower layer; 4) optionally applying a paint layer to the lower layer; 5) optionally applying a further sealer or lacquer layer to the lower layer; 6) curing the sealer or lacquer layer; 7) sanding and polishing the finished lower layer; 8) providing an upper veneer layer; 9) optionally removable fixing the veneer layer to a support; 10) sanding the upper veneer layer; 11) applying a sealer layer to the upper veneer layer; 12) optionally sanding the sealer layer of step 11; 13) applying an open pore lacquer layer to the upper veneer layer; 14) pre-applying a heat-activated adhesive film to a lower surface of the upper veneer layer; 15) selectively removing sections of the upper veneer layer and heat-activated adhesive film by laser cutting to provide a perforated layer; and 16) applying the upper veneer layer to the lower layer and curing the heat-activated adhesive film at a temperature of 75-110°C and a pressure of 5-20 N / cm2 The steps 1) to 15) can be carried out as described herein. The invention also provides an interior part for an automobile comprising a dual finish, comprising a lower layer having a first finish and an upper veneer layer having a second finish, wherein the upper veneer layer is perforated to reveal sections of the lower layer. The interior part can suitably be formed according to the methods described herein. Brief Description of the Drawings Fig. 1 shows views of two exemplary parts with a dual finish according to the invention. Detailed Description of the Invention The following exemplary and non-limiting method describes the steps that were involved in preparing the lower high gloss layer, including the optional steps involved in applying a metal leaf, the steps involved in preparing the upper veneer layer, and the steps involved in applying the veneer to the lower layer to form the final product. The lower layer and the upper veneer layer were initially prepared separately. The lower layer was initially prepared with a prime foil substrate. After this step, a sealer (obtained from Votteler Lackfabrik GmbH &Co. KG) was applied with a spray gun. A polyurethane paint layer was subsequently applied with a spray gun - the paint layer comprised polyurethane paint, hardener and thinner obtained from Votteler Lackfabrik GmbH &Co. KG. Once the paint layer was dry, a polyurethane lacquer was applied (again obtained from Votteler Lackfabrik GmbH &Co. KG) and oven cured at 80°C for two hours. The lacquered lower layer was then sanded and polished to a high gloss finish. In instances where an optional metal leaf finish was desired, the polished surface was cleaned with 3M surface cleaner VHB. A metal leaf size obtained from A. S. Handover Ltd was then applied to provide adhesion for the metal leaf. The metal leaf was then applied and subsequently protected with an additional layer of polyurethane lacquer, as before, applied using a spray gun, subsequently oven cured, and sanded and polished to provide the finished surface. In instances where an optional metal leaf finish was not desired, the polished surface was cleaned but the additional steps of applying size, applying metal leaf and applying an additional lacquer coat were not carried out. Separately, the upper veneer layer was rough cut to shape and, if necessary, multiple veneer pieces were edge glued to form a composite veneer sheet. The veneer layer was then taped to an MDF board to provide stability during subsequent processing and sanded to smooth the upper surface of the veneer. The upper veneer layer was then treated with a UV inhibitor layer and then a sealer (again obtained from Votteler Lackfabrik GmbH &Co. KG), both of which were applied using a spray gun. The treated surface was then denibbed using P320 grit to provide a smooth surface for the application of the open pore lacquer. The open pore lacquer (again obtained from Votteler Lackfabrik GmbH &Co. KG) was also applied using a spray gun. Once these steps had been completed, the veneer layer was removed from the MDF board and a heat-activated adhesive film, or glue sheet, obtained from H.B. Fuller, was applied to the lower surface of the veneer and pre-tacked at 50°C for 5 minutes so that the glue sheet was loosely attached to the veneer layer. A laser was then used to cut the desired pattern into the attached veneer layer and glue sheet. Once the two layers had been formed and the requisite finishes applied, the upper veneer layer was applied to the lower layer using a membrane press to cure the glue sheet. Various temperatures were used in the range of 75-110°C for 40-100 minutes. The curing step was carried out using pressures in the range 5-20 N / cm2 Following curing of the adhesive film, the edges of the assembled product were milled, to smooth the edges of the veneer and yield the final product. Fig. 1 shows two exemplary automotive interior parts comprising a dual finish according to the invention. In Fig. 1(a), the part includes a mixture of round, substantially circular perforations and elongated perforations of differing sizes. In Fig. 1(b), the part includes linear perforations or channels arranged as a series of curved 5 lines that extend to the edge of the part. In each of Fig. 1(a) and Fig. 1(b), the illustrated part (1) comprises a lower layer (2), an upper veneer layer (3). Once assembled, the heat-activated adhesive film joining the two layers is not visible. The perforations (4) in the upper layer permit the lower layer (2) to be seen through the upper veneer layer (3). Thus, Fig. 1 illustrates interior parts prepared according to the 10 invention.

Claims

1. A method of forming a dual finish on an interior part for an automobile comprising:a) providing a lower layer and applying a first finish to the lower layer;b) providing an upper veneer layer and applying a second finish to the upper veneer layer, wherein the second finish is different to the first finish;c) pre-applying a heat-activated adhesive film to a lower surface of the upper veneer layer;d) selectively removing sections of the upper veneer layer and heat-activated adhesive film by laser cutting to provide a perforated layer;e) applying the upper veneer layer to the lower layer and applying heat and / or pressure to cure the heat-activated adhesive film.

2. A method according to claim 1, wherein the first finish is a high gloss lacquer.

3. A method according to claim 1 or claim 2, wherein the second finish is an openpore matte lacquer.

4. A method according to any preceding claim, wherein the heat-activated adhesive film is a polymeric film that forms a temporary bond when placed in contact with the upper veneer layer and forms a permanent bond between the upper and lower layers when subjected to a curing process.

5. A method according to claim 4, wherein the curing process is carried out at a temperature of 75-110°C and a pressure of 5-20 N / cm26. A method according to any preceding claim, wherein step a) comprises:1) providing a lower layer;2) applying a prime foil substrate,3) applying a sealer layer;4) optionally applying a paint layer;5) optionally applying a further sealer or lacquer layer;6) curing the sealer or lacquer layer; and7) sanding and polishing the finished lower layer.

7. A method according to claim 6 , comprising the additional steps:8) cleaning the finished lower layer;9) applying a metal leaf size to the lower layer;10) applying a metal leaf to the prepared surface;11) applying a further sealer or lacquer layer,12) curing the sealer or lacquer layer; and13) sanding and polishing the finished lower layer.

8. A method according to any preceding claim, wherein step b) comprises:1) providing an upper veneer layer;2) optionally removable fixing the veneer layer to a support;3) sanding the veneer layer;4) applying a sealer layer;5) optionally sanding the sealer layer; and6) applying an open pore lacquer layer.

9. A method according to any preceding, wherein step c) is carried out at a temperature of 20-50°C.

10. A method according to any preceding claim, wherein step e) is carried out at a temperature of 75-110°C and a pressure of 5-20 N / cm211. A method according to any preceding claim, wherein the interior part is selected from the list comprising a dashboard, a door panel, a centre console, a footplate, an armrest, a boot floor, a seat back and individual panels or sections thereof.

12. A method of forming a dual finish on an interior part for an automobile comprising:1) providing a lower layer;2) applying a prime foil substrate to the lower layer,3) applying a sealer layer to the lower layer;4) optionally applying a paint layer to the lower layer;5) optionally applying a further sealer or lacquer layer to the lower layer;6) curing the sealer or lacquer layer;7) sanding and polishing the finished lower layer;8) providing an upper veneer layer;9) optionally removable fixing the veneer layer to a support;10) sanding the upper veneer layer;11) applying a sealer layer to the upper veneer layer;12) optionally sanding the sealer layer of step 11;13) applying an open pore lacquer layer to the upper veneer layer;14) pre-applying a heat-activated adhesive film to a lower surface of the upper veneer layer;15) selectively removing sections of the upper veneer layer and heat-activated adhesive film by laser cutting to provide a perforated layer; and16) applying the upper veneer layer to the lower layer and curing the heat-activated adhesive film at a temperature of 75-110°C and a pressure of 5-20 N / cm213. An interior part for an automobile comprising a dual finish, comprising a lower layer having a first finish and an upper veneer layer having a second finish, wherein the upper veneer layer is perforated to reveal sections of the lower layer.

14. An interior part for an automobile comprising a dual finish, formed according to the method of any of claims 1 to 12.

Images