The present disclosure relates to the subject matter disclosed in German application No. 102 09 014.9 of Feb. 25, 2002, which is incorporated herein by reference in its entirety.
The invention relates to a method of producing an interior fitment for vehicles, the interior fitment having on its facing side a wood molding which is provided with a coating.
The invention also relates to an interior fitment for vehicles which comprises a wood molding coated on its facing side.
Interior fitments are increasingly being employed as trim components for the design of vehicle interiors, especially interiors of automobiles. They serve for decoration and are fitted predominantly in the region of the dashboard and the vehicle doors. On their facing side, the interior fitments comprise a wood moldingxe2x80x94wood veneer or even solid wood, for examplexe2x80x94and on the reverse they are normally equipped with a support layer which gives the wood molding the required mechanical stability and which allows the interior fitment to be anchored in the interior of the vehicle.
The wood moldings are customarily provided with a high-gloss varnish coating. For this purpose, a varnish is applied to the facing side of the wood molding, often by spraying. In such a process, two or more coats are generally needed in order to obtain the desired sealing of the wood molding and an extremely glossy surface. The varnishes are customarily based on polyester or polyurethane. They give the interior fitment a clearly visible coating, which admittedly has the advantage that it emphasizes the grain of the wood molding and produces a visually appealing xe2x80x9cdepth effectxe2x80x9d. The varnish coatings of this kind have the disadvantage, however, that they greatly alienate the feel of the wood molding and give it a very unnatural appearance.
It is an object of the present invention to provide a method of producing an interior fitment of the generic type, and to provide an interior fitment produced accordingly, which gives an impression as close as possible to that of nature.
In a method of the type specified at the outset, this object is achieved in accordance with the invention by applying to the wood molding a coating material based on vegetable-oil-modified resins and natural vegetable oils, with the addition to the coating material of ceramic microparticles.
On application, the coating material may have, for example, a waxlike or liquid consistency, and penetrate into the surface of the wood molding.
In a departure from the normal coatings for interior fitments, the method in accordance with the invention does not use a varnish which alienates the natural appearance and feel of the wood molding or forms a covering layer; instead, a coating material is employed which penetrates the wood molding and forms a polymeric network having good resistance properties, with practically complete retention of the natural surface of the wood molding. Accordingly, the wood molding imparts the natural impression of wood both to the eye and the hand, and thereby acquires a particular value. Nevertheless, the interior fitment satisfies the stringent requirements imposed on motor vehicle interior fitments, displaying in particular a high scratch resistance and hardness. The interior fitment in accordance with the invention has the advantage, moreover, that it is inexpensive to repair if damaged, since such repair merely requires that the coating material be reapplied to the wood molding, with no need to uninstall the interior fitment from the vehicle.
The coating employed in accordance with the invention is biodegradable, and so the interior fitment can be disposed of without problems. The use of vegetable-oil-modified resins and natural vegetable oils makes it possible to use only mild-odor solvents for the coating material; in particular, it is possible to do away with the use of toxic and intensely odorous styrene, toluene, benzenes or the like, and also with that of sensitizing isocyanates and intensely odorous solvents.
It has been found, moreover, that the coating of the wood molding can be carried out inexpensively on account of the fact that much less coating material and fewer worksteps are required than is the case when varnishing with polyester or polyurethane varnishes.
It is of particular advantage to apply the coating material in two or more coats: in a first application step, the coating material is applied as a primer without the addition of ceramic microparticles, and at least in a final application step the coating material is applied with the addition of ceramic microparticles. In the first application step, the coating material adopts the function of a primer oil or sealer which penetrates deep into the wood molding, wets the wood substrate, and ensures an optimal bond, i.e., good anchoring and firm adhesion. At least in a final application step, abrasion-enhancing ceramic micro-particles are added to the coating material. The final application step serves to produce a topcoat or performance coat, the coating material with addition of the ceramic microparticles forming a covering material which gives the interior fitment the required service properties. The addition of the abrasion-improved ceramic microparticles ensures the requisite hardness, scratch resistance, and abrasion resistance of the coating.
One preferred embodiment of the method in accordance with the invention envisages drying the applied coating material after the first application step and then in a second application step applying the coating material again as a further primer, without the addition of ceramic microparticles, and in turn drying it. This allows particularly good adhesion of the coating.
It is useful to sand the wood molding after the first application step. By means of the sanding it is possible to ensure particularly effective bonding of the overall coating system.
Drying of the applied coating material is preferably accompanied by the supplying of oxygen; for example, supply of air. This assists the oxidative curing process which takes place following application of the coating material. In the course of this curing process the double bonds present in the unsaturated fatty acids of the dry [sic] oils of the coating material react intermolecularly with one another and form a polymeric network having good resistance properties.
The applied coating material dries preferably at room temperature. It has been found that a drying operation of this kind gives the coating on the wood molding particularly good stability.
The coating material may comprise, for example, linseed- and/or soybean-oil-modified resins.
Natural vegetable oils which can be employed for the coating material include, for example, linseed oils and/or soybean oils.
For applying the coating material a diluent is employed, preferably volatile aliphatic hydrocarbons: isoparaffins and white spirit free from aromatics, for example.
Diluents of this kind are very low in odor and ensure that in its end state the interior fitment exhibits virtually no extraneous odors.
It is useful to add a lead-free drying agent to the coating material, since this makes it possible to accelerate the drying operation.
In order to accelerate the crosslinking reaction of the fatty acids in the coating material, it is of advantage if the coating material comprises zirconium compounds and/or cobalt compounds as drying agents, since these act as catalysts for the crosslinking reaction.
The ceramic microparticles employed in accordance with the invention are added preferably in powder form to the coating material. Ceramic microparticles which can be employed in this context include porcelain powders or porcelainlike powders.
One preferred embodiment of the method in accordance with the invention envisages applying the coating material in a total amount of not more than approximately 150 g/m2. It has been found that such an amount of coating material is sufficient to give the wood molding the properties required for use in the interior of a vehicle, such as scratch resistance and light stability, for example, while ensuring that there is no alienation of the xe2x80x9cwood impressionxe2x80x9d; in other words, both in respect of look and in respect of touch, the natural impression of the wood is retained.
It is useful if in a first application step the coating material is applied in an amount of not more than about 40 g/m2, preferably about 20 g/m2 to about 40 g/m2. It has proven particularly useful if the coating material in the first application step is applied in an amount of about 25 g/m2 to about 35 g/m2.
The final application step takes place preferably with an amount of coating material, including added ceramic microparticles, of not more than about 20 g/m2, preferably about 10 g/m2 to about 15 g/m2.
It is useful if the second application step takes place with an amount of coating material of not more than about 35 g/m2, preferably about 15 g/m2 to about 35 g/m2, with an amount of about 20 g/m2 to about 30 g/m2 having proven particularly useful for giving the coating particularly high hardness and also scratch resistance and abrasion resistance.
The application of the coating material to the wood molding can take place at least in one application step by means of spray application.
Alternatively and/or additionally it is possible to envisage applying the coating material, at least in one application step, by means of a roller or brush to the wood molding.
It has proven particularly advantageous for the coating material to be applied by means of a roller or brush in the first application step and to be sprayed onto the wood molding in the subsequent application steps.
As mentioned at the outset, the invention also extends to an interior fitment for vehicles which comprises a wood molding coated on its facing side, the interior fitment having been produced preferably by the method specified above. In order to ensure that the interior fitment gives an impression close to that of nature, the invention envisages applying to the wood molding a coating material based on vegetable-oil-modified resins and natural vegetable oils, ceramic microparticles being added to the coating material.
As explained above, an interior fitment of this kind has the advantage that it gives the impression of natural wood, both in a visual respect and with a view to its haptic properties, with the fitment being repairable inexpensively at any time in the event of damage, by renewed application of the coating material. Moreover, the interior fitment has extremely low emissions; in particular, it does not include any toxic and intensely odorous styrene.
Ceramic microparticles added to the coating material preferably comprise porcelain powders or porcelainlike powders, which impart particularly high scratch resistance to the interior fitment.
On its reverse the interior fitment preferably has a support layer on which the wood molding is mounted and which comprises anchoring elements for attaching the interior fitment in the interior of the vehicle.