Method for manufacturing a decorative part with natural fiber look and decorative part

Abstract

Method for manufacturing a decorative part with a natural fiber look for vehicles, with a fiber layer arranged on a visible side of the decorative part and recognizable from the outside, in particular in a predetermined color shade, wherein the fiber layer has a fiber structure with interstices, which is formed from fibers, at least some of which are natural fibers, comprehensively the procedural steps: - Dyeing through natural fibers, whereby the natural fibers are treated with a primer, a mordant and a varnish during the dyeing process, - Creating the fiber layer from the fibers, - Wet impregnation of the fiber layer with an aqueous polymer dispersion, so that the polymer dispersion penetrates the fiber layer at least partially and increases the suitability for the penetration of a varnish into the spaces between the fiber structure, - Drying of the wet-impregnated fiber layer, - Securing the fiber layer onto a decorative carrier with an orientation towards the visible side of the decorative part, - Applying a layer of lacquer over the fiber layer arranged on the decorative part carrier to form a transparent surface layer on the visible side of the decorative part, whereby lacquer penetrates into the spaces between the fiber layer.

Description

[0001] The invention relates to a method for manufacturing a decorative part with a natural fiber look for vehicles, having a natural fiber layer arranged on a visible side of the decorative part and recognizable from the outside, and to a decorative part manufactured by the method according to the invention.

[0002] Motor vehicles can utilize a variety of fiber-reinforced composite components or decorative parts containing fibers, some of which also provide fiber optics. Currently, synthetic or mineral fibers, such as carbon fibers, are often used.

[0003] For various reasons, such as changing aesthetic sensibilities and greater environmental awareness, the use of natural materials in vehicles is to be increased, and they are expected to significantly influence surface appearance. However, the natural fibers, or the decorative elements incorporating these fibers, must still meet the requirements, particularly in automotive manufacturing.

[0004] Therefore, decorative parts made with natural fibers must also be adjustable to match the color scheme of the vehicle or the vehicle interior, be temperature and UV light resistant, and abrasion resistant.

[0005] The problem is that natural fibers in their original form do not meet these requirements.

[0006] Fiber layers formed with natural fibers, or the decorative parts made from them, are also often susceptible to warping and edge trimming during processing.

[0007] Dyeing fiber layers or decorative parts containing such natural fibers has also proven difficult, as the fibers absorb mordant strongly and a high application of dye is necessary.

[0008] The prior art is disclosed, for example, in documents DE 10 2009 006 130 A1, DE 20 2004 003 214 U1, WO 2004 / 076 506 A1, DE 197 23 504 C1 and WO 2016 / 075 015 A1.

[0009] A method for manufacturing a decorative part with a natural fiber look for vehicles, featuring a fiber layer arranged on a visible side of the decorative part and visible from the outside, is known, for example, from German patent application DE 10 2015 100 925 A1. This method involves dyeing the natural fibers before processing them into a fiber layer. After the fiber layer is produced, it undergoes wet impregnation, subsequent drying, bonding of the fiber layer to a substrate, and the application of a lacquer coating.

[0010] Further aspects of such processes, particularly with regard to the dyeing of fibers, are also known, for example, from documents EP 2 739 469 B1 and US 2010 / 0 285 274 A1.

[0011] The invention is therefore based on the objective of overcoming the aforementioned disadvantages and providing a method with which decorative parts for motor vehicles can be manufactured with a natural fiber look and improved quality with regard to surface finish, abrasion resistance, UV light and temperature resistance as well as processability.

[0012] This problem is solved by both a combination of features according to claim 1 and claim 2.

[0013] According to the invention, natural fibers are dyed through before being processed into a fiber layer and before impregnation or wet impregnation. Furthermore, a fiber layer, which is at least partially and preferably entirely composed of natural fibers and provides the fiber optics on the visible side of the decorative element, is pre-impregnated with a polymer dispersion to improve the penetration of lacquer, in particular a clear lacquer, into the spaces between the fibers or the fiber layer and to reduce the tendency of any air contained therein to outgas. This also eliminates the need for the otherwise often necessary application of a primer to the fiber layer.

[0014] Specifically, a method for manufacturing a decorative part with a natural fiber look for vehicles is proposed, comprising a fiber layer arranged on a visible side of the decorative part and recognizable from the outside, particularly in a predetermined color, wherein the fiber layer has a fiber structure with spaces, which is formed from fibers, at least some of which are natural fibers. The method according to the invention comprises at least the following process steps: - Dyeing or through-dyeing of natural fibers, wherein the natural fibers are in a raw state during dyeing, i.e., cleaned and preferably separated, but not yet further processed. Accordingly, the dyeing is carried out before the fiber layer is produced and wet impregnation is performed. Through dyeing or through-dyeing, the fibers, and thus also the fiber layer subsequently formed from them, are preferably directly imparted with the intended or predetermined color. - Creating the fiber layer from the fibers. - Wet impregnation of the fiber layer with an aqueous polymer dispersion, so that the polymer dispersion penetrates the fiber layer at least partially and increases the suitability for the penetration of a varnish into the spaces between the fiber structure. - Drying of the wet-impregnated fiber layer. - Securing the fiber layer on a decorative carrier with an orientation towards the visible side of the decorative part, i.e. on a side of the decorative carrier facing the visible side. - Applying a layer of lacquer over the fiber layer arranged on the decorative element carrier to form a transparent surface layer on the visible side of the decorative element, wherein the lacquer penetrates the spaces between the fiber layer. In a cured or solidified state, the lacquer layer is also transparent and preferably completely transparent or translucent.

[0015] Furthermore, a process is proposed which is also characterized by the fact that the natural fibers are dyed through and differs from the aforementioned process in that the fibers are wet-impregnated and dried before the fiber layer is produced from the fibers or the fibers are processed into the fiber layer.

[0016] The wet impregnation of the fiber layer or the individual fibers with the aqueous polymer dispersion, which is based in particular on polyurethane, acrylate or polyvinyl acetate or a mixture thereof, alters the surface structure of the natural fibers or fiber filaments and, if other fibers such as synthetic or mineral fibers are present, also their surface structure, so that the coating cross-links with the fiber layer without leaving air inclusions.

[0017] By dyeing and treating the natural fibers before wet impregnation and before the fiber layer is created, it is prevented that the individual fibers or natural fibers protrude from a plane determined by the fiber layer or from the visible side determined by the fiber layer, thus preventing unevenness.

[0018] Preferably the fibers, in particular the natural fibers and / or the fiber layer formed therefrom, are sized.

[0019] In a particularly advantageous development, the fiber structure consists entirely of natural fibers, such as flax or flax fibers. If the fiber structure does not consist entirely of natural fibers, it can also be partially composed of synthetic and / or mineral fibers, whereby the natural fiber appearance is still provided or determined by the natural fibers.

[0020] In both proposed methods, it is provided according to the invention that the natural fibers are treated with a primer, a mordant and, in particular, a colorless varnish during dyeing.

[0021] For example, during dyeing, before dyeing, or after dyeing, but in any case before wet impregnation, the natural fibers can be treated at least once and preferably several times with at least one additive to increase temperature resistance and / or UV light resistance.

[0022] One variant of the process involves applying the additive directly to the preferably untreated, i.e., not yet dyed, natural fibers and / or adding it to the primer and / or mordant and / or varnish during the dyeing process of the fibers.

[0023] In particular, it is intended that the additive(s) be applied directly to the fibers before dyeing and / or added to the primer and / or mordant and / or varnish during the dyeing process, and that the additive(s) be tailored to the material used as natural fibers and its original color tone, the desired color tone, and the properties to be achieved.

[0024] After the fiber layer has been produced, at least one color layer can be applied, particularly to the visible or dominant side of the fiber layer or its fiber structure, to fine-tune the color. This color layer thus forms an intermediate layer between the fiber layer and the lacquer layer. The color layer is preferably applied by spraying, and the color layer, and in particular the lacquer forming the color layer, can be water- or solvent-based. The color layer not only allows for color adjustment and fine-tuning, but also increases the durability, and especially the UV resistance, of the fiber layer or its fiber structure.

[0025] The fiber layer can also preferably be produced by weaving or interlacing the fibers, at least some of which are natural fibers, so that the fiber layer is in particular a woven fabric.

[0026] Furthermore, when dyeing natural fibers, it can be provided that a first portion of the natural fibers is dyed in a first predetermined shade and a second portion in a second predetermined shade. During the production of the fiber layer, and especially during the weaving of the fibers into the fiber layer, a fiber layer with a predetermined color pattern in the first and second shades can then be produced from the first and second portions of the natural fibers.

[0027] The aqueous dispersion to be used, based on polyurethane, acrylate or polyvinyl acetate or a mixture thereof, has a solids content of 1-70%, more preferably 10-60% and more preferably 25-50%.

[0028] While it is generally not common practice for decorative fiber optic components, one embodiment provides for the fiber layer to receive a primer layer, i.e., an adhesion promoter or bonding agent layer, before being arranged on the decorative component carrier. This primer layer is preferably applied to a side of the fiber layer or fiber structure facing away from the visible side, so that the fiber layer can adhere better to the decorative component carrier via this bonding agent layer.

[0029] In addition to or as an alternative to the primer layer, a fiber interlayer can also be applied to the fiber layer as an adhesion promoter. This fiber interlayer can be made of a nonwoven fabric or nonwoven fibers. The fiber interlayer is particularly advantageous as an adhesion promoter when the decorative element carrier is formed by back-injection of the fiber layer.

[0030] For wet impregnation, the fiber layer is preferably conveyed through a dispersion bath as part of the manufacturing process, so that production takes place on a production line with seamlessly integrated process steps. The fiber layer is transported through the dispersion bath at a speed of 0.5–10 m / min, preferably 1–2 m / min, and remains immersed for 10–60 seconds. The wet impregnation process results in an increase in the fiber layer's basis weight of 1–50 g / m², depending on the fabric type. 2 , preferably 5 to 20 g / m² 2 learns.

[0031] After wet impregnation, the drying step advantageously takes place in a drying section at a temperature of 20–120°C, particularly preferably 60–120°C, until a residual moisture content of less than 1% is reached. Like passing through the dispersion bath, a drying section enables drying to be integrated into the manufacturing process within the same production line.

[0032] In one alternative, the wet-impregnated and dried fiber layer is attached to the decorative carrier by laminating. In a second alternative, the attachment is achieved by back-injecting the decorative carrier to the fiber layer using an injection molding process. Furthermore, three-dimensional forming processes of the decorative carrier with the attached fiber layer are also possible. The wet impregnation with the aforementioned polymer dispersions also improves fiber and shear strength and reduces the tendency for fiber breakage, particularly of natural fibers, during laminating and forming processes.

[0033] The same applies to subsequent processing steps and in particular edge processing, for example by machining, such as milling.

[0034] In an advantageous embodiment, the application of the lacquer layer is carried out, in particular to produce a high-gloss surface forming the visible side, by pouring over the fiber layer.

[0035] The coating layer is formed in particular from a two-component polyurethane casting system, whereby both aromatic or aliphatic as well as lightfast and non-lightfast polyurethane coatings can be used.

[0036] Alternatively, if an open-pore surface is to be created on the visible side, the coating is preferably applied using a spraying method.

[0037] The process is particularly cost-effective if the fibers from which the fiber fabric is formed, and especially the natural fibers, are processed as individual fibers or as fiber bundles, or the fiber fabric as pre-made roll goods, are processed in an integrated manufacturing process, i.e., unwound from a roll, dyed, wet-impregnated, dried, and either rewound onto a roll or cut directly to size for arranging the fiber layer on the decorative carrier according to the size of the decorative carrier.

[0038] In a further embodiment, the fiber layer is provided with an additional support fabric, making it easier to process and position on the decorative carrier. The support fabric is preferably arranged on a side of the fiber layer facing away from the visible side, so that the visible side and the overall appearance remain defined by the natural fibers.

[0039] In addition to the process steps, possible steps include milling the decorative part after applying the paint and polishing the surface, whereby the polishing effort required due to the application of the method according to the invention is reduced many times over.

[0040] Other advantageous embodiments of the invention are characterized in the dependent claims.

[0041] The invention is not limited in its implementation to the preferred embodiments described above. Rather, a number of variants are conceivable, which utilize the illustrated solution even in fundamentally different designs. For example, the lamination of the fiber layer can be carried out manually or mechanically. The decorative element carrier can also be made of injection-molded material or wood laminate.

Claims

[1] Method for producing a decorative part with natural fibre optics for vehicles with a fibre layer arranged on a visible side of the decorative part and visible from the outside, in particular in a predetermined colour, wherein the fiber layer has a fiber structure having interstices which is formed from fibers, at least a part of which are natural fibers, comprehensively the procedural steps: - Dyeing of natural fibres, whereby the natural fibres are treated with a primer, a stain and a varnish during the dyeing process, - Producing the fiber layer from the fibers, - wet impregnation of the fiber layer with an aqueous polymer dispersion, so that the polymer dispersion penetrates at least partially into the fiber layer and increases the suitability of a varnish for penetrating into the interstices of the fiber structure, - Drying the wet-impregnated fibre layer, - Fixing the fiber layer on a trim support with an orientation towards the visible side of the trim, - Applying a layer of lacquer over the fibre layer arranged on the trim support to form a transparent surface layer on the visible side of the trim, whereby lacquer penetrates into the spaces between the fibre layer. [2] Method for producing a decorative part with natural fibre optics for vehicles with a fibre layer arranged on a visible side of the decorative part and visible from the outside, in particular in a predetermined colour, wherein the fiber layer has a fiber structure having interstices which is formed from fibers, at least a part of which are natural fibers, comprehensively the procedural steps: - Dyeing of natural fibres, whereby the natural fibres are treated with a primer, a stain and a varnish during the dyeing process, - wet impregnation of the fibers with an aqueous polymer dispersion, so that the polymer dispersion penetrates at least partially into the fibers and increases the suitability of a varnish for penetrating into the interstices of the fiber structure of the fiber layer, - Drying the wet-impregnated fibers, - Producing the fibre layer from the wet-impregnated and dried fibres, - Fixing the fiber layer on a trim support with an orientation towards the visible side of the trim, - Applying a layer of lacquer over the fibre layer arranged on the trim support to form a transparent surface layer on the visible side of the trim, whereby lacquer penetrates into the spaces between the fibre layer. [3] Method according to claim 1 or 2, wherein the fiber layer and / or the fibers and in particular the natural fibers are sized. [4] Method according to one of the preceding claims, on a side of the fiber layer facing the visible side, in particular by spraying, at least one color layer is applied for fine adjustment of the color tone, which forms an intermediate layer between the fiber layer and the lacquer layer. [5] Method according to one of the preceding claims, wherein the fibre structure is made entirely of natural fibres and in particular flax fibres or wherein the fiber structure is partly formed from synthetic fibers and / or mineral fibers. [6] Method according to one of the preceding claims, wherein the lacquer with which the natural fibres are treated during dyeing is colourless. [7] Method according to one of the preceding claims, wherein the natural fibers are treated with at least one additive to increase temperature resistance and / or UV light resistance before wet impregnation. [8] Process according to the preceding claim, wherein the natural fibres are treated several times with the additive. [9] Method according to the two preceding claims, wherein the additive is applied directly to the natural fibres and / or is added to the primer and / or the stain and / or the varnish. [10] A method according to any one of the preceding claims, wherein the fiber layer is produced by weaving. [11] Method according to one of the preceding claims, characterized by that the aqueous polymer dispersion is based on polyurethane, acrylate or polyvinyl acetate or a mixture thereof. [12] Method according to one of the preceding claims, characterized by that the fibre layer receives a primer layer and / or intermediate fibre layer to create adhesion before being arranged on the trim part carrier, in particular on its side facing away from the visible side. [13] Method according to one of the preceding claims, characterized bythat the fiber layer is attached to the trim part carrier by lamination. [14] Method according to one of the preceding claims 1 to 12, characterized by that the trim part carrier is back-injected onto the fiber layer. [15] Method according to one of the preceding claims, characterized by that the fiber layer also has a supporting fabric. [16] Decorative part with natural fiber optics manufactured according to at least one of the preceding claims.