GB2630357A - Burnt wood for automotive interior surface - Google Patents

Abstract

A method of applying a decorative finish to an interior veneer for an automobile, the method comprising controlled burning of a surface of the veneer, and an interior veneer for an automobile having a burnt wood finish.

Description

Burnt Wood for Automotive Interior Surface

Introduction

The present invention relates to methods of applying a decorative finish to an interior veneer for an automobile, methods of forming a veneer on a three dimensional part for an automobile and applying a decorative finish, and to interior veneers and three dimensional interior parts for an automobile comprising such veneers having a decorative finish.

Background

It is desirable to add an aesthetically pleasing decorative finish to interior veneer for an automobile. As such, a method of applying a decorative finish to a veneer is desired, especially when the veneer is applied to interior parts of an automobile having complex three dimensional surface geometries.

A traditional technique for preserving and applying a decorative finish to wood is the Japanese technique of Yakisugi or burnt cedar. The Yakisugi technique involves limited burning or charring of the surface of wood, without complete combustion, to protect the wood from decay and water damage, and to increase fire resistance. The resulting charred effect is also considered to be aesthetically pleasing. This technique is traditionally applied in outdoor environments, for example to the exterior of wooden buildings. As such, it is applied to solid, bulk timbers or to exterior cladding of significant thickness. Exterior wooden cladding might for example have a thickness of about 15mm.

The Yakisugi technique has not been applied to thin veneers, for example veneers of less than about 1.5mm in thickness, as might be used for fine furniture and automotive interiors.

In addition, traditional exterior application of the Yakisugi technique results in an uncoated surface or may additionally comprise further protection with an exterior-grade preservative, such as a polyurethane coating or an oil. Such finishes are not suited to the interior environment of an automobile as they can have undesirable tactile -2 -qualities and/or result in a surface with a coating that could be transferred to skin and/or clothing.

Accordingly, translating the Yakisugi technique to fine veneers suitable for use in automotive interiors, as such veneers are much thinner than the bulk timber or cladding used in traditional Yakisugi techniques, and are thus more fragile and less rigid. Veneers suitable for automotive interiors are also more susceptible to damage and/or distortion during the burning process than the substrates used in the traditional Yakisugi techniques. In addition, different surface finishes are required, that are suitable for an automobile interior rather than the original external application.

In addition, application of a burnt finish to veneered parts is challenging, as such parts have complex three dimensional geometries, rather than having a generally flat surface, as is seen in the traditional exterior application of the Yakisugi technique.

Accordingly, an aim of the present invention is the provision of methods for applying a decorative finish to veneers, and for forming a veneer on a three dimensional part and applying a decorative finish without the problems noted above. A further aim is to provide interior veneers and three dimensional interior parts for an automobile comprising such veneers comprising a decorative finish.

Summary of the Invention

The invention provides a method of applying a decorative finish to an interior veneer for an automobile, the method comprising controlled burning of a surface of the veneer. 25 The veneer is typically a thin layer of fine wood that can be applied to a surface to give the appearance that the entire surface is wood. It is envisaged that the veneer provided in the first step of the method of the invention could be any known wood veneer. The veneer may be formed from natural wood (comprising only a single type of wood) or it may be engineered (comprising a mixture of woods). Suitable woods include Ash, Beech, Birch, Bocote, Bubinga, Chestnut, Cherry, Ebony, Elm, Eucalyptus, Mahogany, Maple, Koa, Larch, Lemonwood, Oak, Olive, Paldao, Palm, Rosewood, Santos palisander, Sapele, Sindora, Sycamore, Teak, Tulip, Walnut, Wenge, and Zebrano. -3 -

Typically, the thickness of the veneer is from 0.2mm to 1.5mm, preferably from 0.3mm to 1.0mm, most preferably from 0.4mm to 0.75mm (for example approximately 0.5mm).

Generally in methods of the invention, the controlled burning is limited to the outer layer of the veneer. Thus, the controlled burning is limited to the top layer, or face layer, of the veneer. Typically, the controlled burning does not extend to the full thickness of the veneer, and damage to the structural layers below the top layer of the veneer, and damage to underlying substrate materials, such as backing layers and the interior part to which the veneer is applied, is avoided.

This can be achieved by carrying out the controlled burning using a blow torch with a limited flame size to burn the top layer of the veneer, whilst avoiding ignition and or excessive heat transfer to the layers below the outer layer of the veneer. The flame can be controlled manually, allowing the operator to react immediately to different responses of different sections of the veneer to the application of heat, and to move the flame to follow the contours of the object to which the veneer is applied. Optionally, a guide can be used, for example in the form of a rail mounted at a fixed distance from the surface of the veneer, to help achieve a consistent burn across the surface of the veneer. Optionally, the flame size can be adjusted for different sections of the veneer. For example, a larger flame may be used on relatively flat sections of the veneer, and a smaller flame may be used on the edges or on sections having complex geometries.

Controlled burning as described herein, including use of a limited flame size, can reduce or avoid delamination and deformation of veneers and veneered parts.

Alternatively, the controlled burning can be carried out using a fixed heat source such as a blow torch, with the veneer being moved relative to the heat source. For example, 30 the veneer or veneered part can be mounted on a movable armature or rig and moved relative to the heat source, either manually or under the control of a robotics system.

Optionally, the controlled burning is applied to only a portion of a veneer or veneered part, resulting in a product that has areas having a burnt wood finish and other areas -4 -having a natural wood finish. The areas of burning can be demarcated, by applying a mask to the surface of the veneer prior to carrying out the controlled burning, so that the areas having a natural wood finish are protected from the heat source.

Preferably, the veneer is brushed and/or air blasted after the controlled burning.

Physical brushing, and/or blasting with an air gun helps to remove soot, ash, and or friable sections of the burnt surface layer of the veneer prior to the application of sealant and/or lacquer layers. The brushing and/or air blasting step or steps may improve adhesion of the sealant and/or lacquer layers to the veneer, and these steps may also help achieve a more uniform finish on the final product.

Optionally, a sealant is applied after the controlled burning. Thus, the method may comprise a step of applying a sealant to the veneer. In preferred embodiments, at least a single layer of sealant is applied to the veneer. In some embodiments two or more layers of sealant may be applied to the veneer. Typically, the sealant is applied as a continuous layer over the entire veneer. Typically, the sealant is a polyurethane-based sealant. Suitable sealants can be obtained from Votteler®.

Typically, a sealant is applied before a lacquer (see below) to stabilise the burnt surface of the veneer. The presence of a sealant layer additionally promotes adhesion of the subsequent lacquer layers to the veneer. The use of two or more sealant layers is preferred, to ensure sealant penetration into the burnt surface of the veneer and to provide for improved adherence of any subsequent lacquer layers.

Optionally, a lacquer layer is applied after the controlled burning and, when present, after a sealant has been applied. In some embodiments, two or more lacquer layers are applied.

Accordingly, the method may comprise a step of applying a lacquer. It is preferred that a lacquer layer is applied, since a lacquer layer is believed to assist in preserving the wood of the veneer whilst also leading to the desired wood finish. Typically, a lacquer layer (when present) is the outer layer -5 -The lacquer may be selected depending on the desired finish of the interior part. Examples of suitable lacquer types include high gloss lacquer and open pore lacquer (also referred to as matt satin finish lacquer). The type of lacquer selected may affect the number of lacquer layers applied to the veneer. Typically, a greater number of lacquer layers are applied when using high gloss lacquer (for example 6 layers of more, preferably 8 layers or more, more preferably 10 layers or more), leading to a greater thickness of the lacquer overall compared to when open pore lacquer is used.

Typically, high gloss lacquer on a veneer has a total thickness of 0.5mm to 2mm, preferably 0.7mm to 1.5mm, most preferably 0.8mm to 1.2mm (for example approximately 1 mm). Excess layers of lacquer may be applied leading to an initial greater lacquer thickness, before the total lacquer thickness is reduced to the desired range during polishing.

The thickness of individual lacquer layers depends on the material of the lacquer.

Typically, individual layers of high gloss polyester lacquer have a thickness of approximately 100 microns to 150 microns. Typically, individual layers of high gloss polyurethane lacquer have a thickness of from 40 microns to 50 microns.

When open pore lacquer is used, typically only a single layer of lacquer is used of negligible thickness. This allows the texture of the wood veneer to be felt through the lacquer. The thickness of a single layer of open pore lacquer is typically negligible.

As for the sealant, the lacquer is typically applied as a continuous layer over the entire 25 veneer.

Suitable high gloss lacquers include polyester and polyurethane lacquers, and a suitable open pore lacquer is a polyurethane lacquer After or during application of the lacquer, there may be additional finishing steps. For example, the lacquered veneer may be sanded to produce a smooth finish. Sanding is typically preferred when high gloss lacquer is used to produce a smooth untextured finish, with a sanding step being carried out at least before application of the final lacquer layer, preferably before application of the second and all subsequent lacquer -6 -layers. When high gloss lacquer is used, there is typically also a polishing step after the final lacquer layers are applied. However, a sanding step is typically not used with open pore lacquer. Therefore, when open pore lacquer is used, the texture of the veneer can typically still be felt through the lacquer.

In some embodiments, a milling step is carried out as an additional finishing step. This step may be used, for example, to smooth the edges of the veneer. Suitable milling machines are known in the art, and include CNC milling machines from Hamuel Reichenbacher, Kelch GmbH and Maka.

As a final step, the method may include applying the veneer onto an interior part of an automobile. Methods of applying veneer onto separate parts are standard in the art. Preferably, the veneer is applied to the interior part using a membrane press or a hydraulic press.

The interior part may be any interior part of an automobile to which a veneer can be applied. Suitable interior parts include the dashboard, the door panels, the centre console, the footplates, armrests, boot floors, floor mats, seat backs and individual panels or sections thereof.

Alternatively, the veneer may be formed on a three dimensional part before the controlled burning, rather than carrying out controlled burning on the veneer, either alone or mounted on a backing layer. By forming the veneer on a three dimensional part before the controlled burning, steps involving handling the veneer after burning are reduced, thus avoiding potential damage resulting from altered mechanical properties of the veneer after burning. For example, after burning, some veneers may become more brittle or prone to damage, and reducing the handling of the veneer and processing steps after burning reduces the risk of damage and/or wastage of materials.

The invention also provides a method of applying a decorative finish to an interior veneer for an automobile, the method comprising: (i) controlled burning of the face layer of a veneer; (ii) applying one or more layers of a sealant to the burned veneer; and -7 - (Hi) applying one or more layers of lacquer to the sealed burned veneer.

The invention also provides a method of forming a veneer on a three dimensional part for an automobile and applying a decorative finish, the method comprising: (i) providing a veneer; (H) optionally mounting the veneer on a backing; (Hi) pressing the veneer onto the three dimensional part; (iv) optionally repairing the veneer, if required; (v) controlled burning of the face layer of the veneer; (vi) optionally applying a sealant to the veneer; (vii) optionally milling the veneer; (viii) applying one or more layers of lacquer; and (ix) optionally milling the veneer Optionally, the veneer may be sanded to form a rough surface at any stage before the controlled burning, for example after mounting onto a backing or after pressing. Typically, the veneer is sanded using sandpaper with grit of from 80 to 320. In some cases, the veneer may be sanded multiple times with progressively finer grit sandpaper. For example, the veneer may first be sanded using 120 grit sandpaper, followed by sanding with 240 grit sandpaper.

The method may comprise mounting the veneer on a backing. This can provide useful structural support for the veneer. Suitable materials for the backing include pre-impregnated glue sheets. These sheets can be applied to the veneer using the pressure and heat of a conventional hydraulic press, without the need for additional adhesive. Typically, the thickness of a backing layer (where present) is approximately 0.2mm to 1.5mm, preferably from 0.3mm to 1mm, most preferably from 0.4mm to 0.8m m.

In embodiments where the method additionally comprises a step of mounting the veneer on a backing, this step is typically carried out prior to the sanding step. The sanding step can therefore reduce the effect of any glue bleed through the veneer as a result of the backing process. -8 -

The step of pressing the veneer onto the three dimensional pad is typically carried out using a membrane press. Typically, the pressing step is carried out at a temperature of less 90°C, preferably less than 80°C, most preferably less than 70°C (for example approximately 65°C).

The use of a membrane press is conventional in the art. An example of a suitable membrane press can be obtained from Global Vacuum Presses®. Alternatively, a hydraulic press can be used.

Following the pressing step, a repairing step may be carried out in which any tears in the veneer or minor damage as a result of the pressing step can be repaired. A repairing step is only required in embodiments where minor damage occurs to the veneer during pressing. Tears in the veneer may be repaired by pressing additional small sections of veneer to the teared area. Minor damage may also be repaired by hand colouring small sections of the veneer.

The controlled burning step, and the steps of applying a sealant and/or a lacquer are as described above.

In some embodiments, a milling step is carried out as an additional finishing step. This step may be used, for example, to smooth the edges of the veneer. When high gloss lacquer is used, the milling step (when present) is typically carried out after the one or more layers of lacquer have been applied. When open pore lacquer is used, the milling step (when present) is typically carried out before the one or more layers of lacquer are applied. Suitable milling machines are known in the art, and include CNC milling machines from Hamuel Reichenbacher, Kelch GmbH and Maka.

The invention also provides an interior veneer for an automobile having a burnt wood finish. Preferably, the burnt wood finish is obtained using the methods of the invention.

Also provided is a three dimensional interior part for an automobile comprising a veneer having a burnt wood finish. Preferably, three dimensional interior pad is formed according to a method of the invention. -9 -

Brief Description of the Drawings

Fig. 1 shows a sample panel comprising a veneer that has been partially subjected to controlled burning according to the invention, sealed and lacquered with an open pore polyurethane lacquer.

Fig. 2 shows a sample panel comprising a veneer that has been partially subjected to controlled burning according to the invention, sealed and lacquered with a high gloss polyurethane lacquer.

Fig. 3 shows an exemplary car interior comprising a dashboard insert having a bunt wood veneer according to the invention.

Detailed Description of the Invention

Figure 1 shows a sample panel comprising a veneer that has been partially subjected to controlled burning according to the invention. First, a 0.5 mm thick veneer formed of ash burr wood was obtained. The veneer was then rough cut to approximately 50 cm by 40 cm in size. The veneer was then applied to a substate (in this case a solid wood block) using a Global Vacuum Presses® membrane press at 65°C to press veneer onto the substrate.

The veneer was sanded using 120 grit sandpaper, followed by 240 grit sandpaper. A section of the veneer was then exposed to controlled burning using a standard blow torch with a limited flame size. Part of the veneer surface (1) was left untreated, whereas another part of the veneer surface (2) was subjected to controlled burning of the surface layer. Care was taken to avoid igniting the veneer or burning deeper than the surface layer of the veneer.

After allowing the veneer to cool, the surface layer was brushed and then blasted with an air gun to remove, soot, ash and any loose surface material, and to improve adhesion of the subsequent sealant and lacquer layers.

After the brushing and air blasting steps, two layers of sealant was applied across the whole surface of the veneer. The sealant was applied using a gravity-fed spray gun. The sealant used was a polyurethane-based sealant from Votteler GmbH. The -10 -thickness of the sealant layer was negligible. Sealant was used to stabilise the burnt surface of the veneer and to improve the adhesion of the lacquer to the veneer, improving the long term durability of the printed veneer. Application of two sealant layers resulted in better penetration of sealant into the burnt surface region of the veneer.

After the sealant was applied, one layer of open pore polyurethane lacquer was applied by spraying using a gravity-fed spray gun and this was then left to dry. The use of open pore lacquer enables the grain and texture of the wood to be both seen and felt through the lacquer. The polyurethane lacquer used to produce the printed design of figure 1 was obtained from Votteler GmbH.

Figure 2 shows a sample panel comprising a veneer that has been partially subjected to controlled burning according to the invention using the same initial steps as the panel shown in figure 1. As was the case for the veneer of Figure 1, part of the veneer surface (3) was left untreated, whereas another part of the veneer surface (4) was subjected to controlled burning of the surface layer.

After the sealing step, the veneer shown in Figure 2 was further coated with a high gloss polyurethane lacquer, rather than the open pore lacquer shown in Figure 1. The lacquer was applied in a similar manner, but ten layers of high gloss lacquer were applied. Before application of each subsequent layer of lacquer, the surface was sanded with 240 grit sandpaper, and after application of the final layer of lacquer, the surface was polished. This resulted in a smooth, untextured finish.

Figure 3 shows an exemplary automotive interior comprising a wooden dashboard panel (5) with an applied burnt wood finish according to the invention. Thus, Figure 3 illustrates an application of veneered parts treated according to the invention.

Examples

Testing Samples Samples of three dimensional parts having applied veneers treated according to the method of the invention have undergone and successfully completed standard adhesion testing.

Claims (1)

1. Claims 1. A method of applying a decorative finish to an interior veneer for an automobile, the method comprising controlled burning of a surface of the veneer 2. A method according to claim 1, wherein the controlled burning is limited to the outer layer of the veneer.3. A method according to claim 1 or claim 2, wherein the veneer is brushed after the controlled burning.4. A method according to any of claims 1 to 3, wherein the veneer is air blasted after the controlled burning.5. A method according to any preceding claim, wherein a sealant is applied after the controlled burning.6. A method according to any preceding claim, wherein the sealant is a polyurethane-based sealant.7. A method according to any preceding claim, wherein a lacquer layer is applied after the controlled burning and, when present, after a sealant has been applied.8. A method according to claim 7, wherein two or more lacquer layers are applied.9. A method according to claim 7 or claim 8, wherein the lacquer is selected from a polyester or polyurethane lacquer 10. A method according to any preceding claim, wherein the veneer is applied to an interior part of an automobile.11. A method according to claim 10, wherein the interior part is selected from the list comprising the dashboard, the door panels, the centre console, the footplates, armrests, boot floors, floor mats, seat backs and individual panels or sections thereof.-12 - 12. A method according to any preceding claim, wherein the veneer is formed on a three dimensional part before the controlled burning.13. A method of applying a decorative finish to an interior veneer for an automobile, the method comprising: (i) controlled burning of the face layer of a veneer; (ii) applying one or more layers of a sealant to the burned veneer; and (Hi) applying one or more layers of lacquer to the sealed burned veneer 10 14. A method of forming a veneer on a three dimensional part for an automobile and applying a decorative finish, the method comprising: (i) providing a veneer; (H) optionally mounting the veneer on a backing; (iii) pressing the veneer onto the three dimensional part; (iv) optionally repairing the veneer, if required; (v) controlled burning of the face layer of the veneer; (vi) optionally applying a sealant to the veneer; (vii) optionally milling the veneer; (viii) applying one or more layers of lacquer; and (ix) optionally milling the veneer 15. An interior veneer for an automobile having a burnt wood finish.16. An interior veneer for an automobile according to claim 15, wherein the burnt wood finish is obtained using the method of any of claims 1 to 13.17. A three dimensional interior part for an automobile comprising a veneer having a burnt wood finish.18. A three dimensional interior part for an automobile comprising a veneer having a burnt wood finish formed according to the method of claim 14.