Abstract:
The invention relates to an interior fitting for the trim of a motor vehicle interior. Said interior fitting comprises a base element and a coating which at least partially covers at least the visible side of said base element. The aim of the invention is to develop one such interior fitting in such a way that it has a long-lasting surface quality. To this end, the coating comprises an outer layer element which is fixed to the base element by means of a connection layer. The invention also relates to a method for producing one such interior fitting.

Description:
[0001]     The present invention relates to the subject matter disclosed in international application No. PCT/EP02/01473 of Feb. 13, 2002, which is incorporated herein by reference in its entirety and for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to an interior fitting with the features of the preamble of claim  1  and to a method for producing it.  
         [0003]     Interior fittings with a coated, for example varnished, base part are frequently used for the interior trim of motor vehicles. Wooden molded parts, which may be of a solid form or formed as veneer parts, are especially used as base parts. On the visible side of the base part, it is usual for a coating in the form of a transparent varnish or resin layer to be applied, so that a usually shiny and long-lasting surface is produced. The base part is thereby sealed on the visible side and its structure is additionally emphasized. For this purpose, the base part is usually coated with a layer of varnish about 0.5 to around 0.8 mm thick.  
         [0004]     The production of the coating generally takes place by the varnish being sprayed or painted onto the surface of the base part to be coated. To obtain the desired sealing and a shiny surface emphasizing the structure of the base part, a number of layers are required for this. This entails considerable expenditure in terms of cost and time.  
         [0005]     In DE-C-43 20 893 it is proposed to place the base part into a cavity of a mold part, a gap being formed between the surface region of the base part to be coated and the associated wall of the cavity and filled with a liquid surface coating material, which subsequently cures.  
         [0006]     Although the use of a coating in the form of a layer of varnish which is produced either by spraying on or by a molding operation as explained above lends the interior fitting an optically appealing effect and also produces a sealing effect, in particular when base parts produced from wood are used, the desired long-lasting surface quality of the interior fitting cannot be ensured in all cases.  
         [0007]     DE-A-199 09 869 discloses an interior fitting in which a base part in the form of a carrier element is coated on the visible side with an adhesive, and a decorative layer, for example a frangible thin layer of stone, is then applied to the layer of adhesive. The decorative layer is covered with an elastic element, for example a rubber sheet, which is then subjected to pressure for adhesively bonding the decorative layer to the carrier element. Subsequently, the elastic element is removed from the decorative layer again by exposure to heat and/or exposure to a solvent.  
         [0008]     In U.S. Pat. No. 3,551,232 there is a description of an interior fitting with a substrate and an outer layer, in which the substrate has a multiplicity of through-openings. The substrate is coated on the visible side with an adhesive, on which the outer layer is then positioned. On the rear side, facing away from the outer layer, the substrate is subsequently subjected to a negative pressure and the outer layer is heated, so that it is sucked through the through-openings of the substrate, adapts itself in its form to the profile of the substrate and is adhesively bonded to the substrate. An interior fitting which is produced using a similar vacuum forming process is disclosed in U.S. Pat. No. 5,629,085.  
         [0009]     It is an object of the present invention to develop an interior fitting of the generic type in such a way that it has an improved surface quality.  
       SUMMARY OF THE INVENTION  
       [0010]     This object is achieved according to the invention in the case of an interior fitting of the type stated at the beginning by the connecting layer comprising a connecting material which is introduced between the base part and the outer layer element under application of pressure.  
         [0011]     The forming of the coating with an outer layer element and a connecting layer has the advantage that the individual layer elements can be respectively optimized for different functional requirements of the coating, so that for example a sealing of the base part and also both an appealing esthetic effect and a long-lasting surface quality are ensured. The sealing may in this case take place by means of the connecting layer, while a high abrasion resistance and the long-lasting surface quality of the coating are ensured by the use of an outer layer element.  
         [0012]     According to the invention, the connecting layer comprises a connecting material which is introduced between the base part and the outer layer element under application of pressure. For example, it may be provided that the connecting material can be pressed between the base part and the outer layer element by means of a piston-cylinder unit.  
         [0013]     It is advantageous if the connecting material can be introduced by means of a positive pressure of around 0.3 bar to about 3.5 bar, preferably 0.5 bar to 2 bar. The use of such a positive pressure ensures that the connecting material in the liquid state distributes itself uniformly between the base part and the outer layer element, with virtually no gas bubbles being formed.  
         [0014]     It is of particular advantage if the connecting layer comprises a connecting material which can be introduced in the liquid state between the base part and the outer layer element and subsequently can be cured. This permits efficient production of the interior fitting, with short process times being achievable, in that the base part and the outer layer element are placed one on top of the other and a liquid connecting material is subsequently introduced between the base part and the outer layer element and then cures. The connecting material may not only serve for the sealing of the base part and the fixing of the outer layer element, but may additionally perform a buffering function, in order to compensate for the different thermal expansions of the base part and the outer layer element. The outer layer element in turn not only provides the interior fitting with a high surface quality, but reduces the gas emission of toxic substances, for example styrene, which are used for the connecting material. The finished interior fitting is therefore also distinguished by particularly low gas emission of harmful substances.  
         [0015]     Especially low-cost production of the interior fitting can be achieved by the connecting material being able to be cured by being subjected to UV radiation. For this purpose, it may be provided that the connecting material comprises UV-radiation-sensitive sensitizers, which are selected in such a way that, when they are subjected to UV radiation, they trigger a chain reaction which leads to curing of the connecting material. The proportion of UV-radiation-sensitive sensitizers is preferably chosen such that, when it is subjected to UV radiation, the connecting material cures within a time period of a few minutes, for example less than 3 minutes, at least to the extent that the interior fitting can be handled. The application of a coating to the base part can consequently be carried out within a few minutes.  
         [0016]     The connecting material is preferably transparent in the cured state, since this allows the esthetic effect of the interior fitting to be additionally improved.  
         [0017]     The connecting layer may for example comprise a layer of adhesive, with a two-component adhesive especially being used.  
         [0018]     In the case of a particularly preferred embodiment it is provided that the connecting layer comprises a layer of varnish or resin. In this case, a synthetic resin material may be used especially, for example a polyester or a polyurethane-, acrylic- or epoxy-based synthetic resin.  
         [0019]     The fixing of the outer layer element on the visible side of the base part takes place, as explained, by means of the connecting layer. The outer layer element consequently does not have to have any holding function.  
         [0020]     To achieve an esthetically especially advantageous surface quality of the interior fitting, it is advantageous if the outer layer element is produced from a transparent material.  
         [0021]     The outer layer element is preferably produced from plastic. Thermoplastics have proven to be advantageous for this, especially polycarbonates.  
         [0022]     In the case of an embodiment of the interior fitting according to the invention which can be produced at particularly low cost, the outer layer element is produced from a film. The use of a film permits easy handling. In particular, the film can be preformed, for example deep drawn, at low cost. In this case, it is advantageous if the film can be clamped onto the base part to be coated.  
         [0023]     It is of advantage if the film can be applied to the base part by deep drawing. For this purpose, a deep drawing installation known per se can be used, with the aid of which the base part can be coated with the film.  
         [0024]     The thickness of the preformed film may comprise in particular about 50% to approximately 90% of the overall layer thickness of the coating, preferably a thickness of approximately 0.4 mm to around 0.7 mm.  
         [0025]     Alternatively it may be provided that the outer layer element takes the form of a prefabricated injection-molded part. The injection-molded part can preferably be placed on the visible side of the base part and fixed on the latter by means of the connecting layer.  
         [0026]     It is of particular advantage if the injection-molded part is shaped in the form of a shell, since the mounting of the interior fitting is simplified as a result. Particularly simple mounting can be achieved by it being possible for the injection-molded part to be placed onto the base part.  
         [0027]     To increase the esthetic effect of the interior fitting, it may be provided that a decorative material or various decorative materials are disposed between the outer layer element and the base part. For this purpose, textiles, shavings, natural materials, such as for example leaves, horn, sand and the like, glass-fiber and/or carbon-fiber fabric or any other visually appealing substances can be used especially. The decorative materials are fixed on the base part by means of the connecting layer and subsequently covered by the outer layer element. The connecting layer may completely surround the decorative materials.  
         [0028]     The connecting layer may not only be used for fixing the outer layer element, but additionally serve for fixing a supporting element, supporting the base part on the rear side. For this purpose, it may be provided that the connecting layer is disposed on the visible side and on the rear side of the base part and that the base part is held on the rear side by the supporting element, which is fixed on the base part by means of the connecting layer. It may be provided in particular that the connecting layer completely surrounds the base part, so that the base part is sealed on all sides. The supporting element lends the base part the desired dimensional stability and can be fixed on the base part by means of the connecting layer. In addition, the supporting element may comprise holding parts, with the aid of which the interior fitting can be fastened in the interior of a motor vehicle.  
         [0029]     Decorative parts, for example a textile material, mineral substances, wood and in particular a laminate which is preformed but not independently dimensionally stable, for example with use of a wood veneer, may be used especially as the base part.  
         [0030]     It is of particular advantage if the supporting element is produced from a transparent material, in particular from a plastics material.  
         [0031]     It has proven to be advantageous to form the supporting element as a prefabricated injection-molded part, especially shaped in the form of a shell, which can preferably be mounted on the rear side of the base part.  
         [0032]     It is advantageous if the supporting element has a receptacle for a lighting element, since this provides the possibility of backlighting the interior fitting in a visually appealing manner.  
         [0033]     As mentioned at the beginning, the invention also relates to a method for producing an interior fitting with improved abrasion resistance.  
         [0034]     This object is achieved by a method with the features of claim  23 .  
         [0035]     The method according to the invention is distinguished inter alia by the fact that an outer layer element is preformed and clamped to the base part, in order to introduce between the outer layer element and the base part the connecting material in the liquid state and cure it.  
         [0036]     It is of advantage if the outer layer element is produced from a plastics material, for example in the form of a film of plastic. This provides the possibility of preforming the outer layer element, preferably by a deep drawing process. It is particularly advantageous here if the outer layer element is applied to the base part by deep drawing and is subsequently clamped to the latter. This permits especially low-cost production of the internal fitting, since the molding of the outer layer element can be performed at the same time as it is applied to the base part.  
         [0037]     Alternatively, it may be provided that the outer layer element is preformed by an injection-molding process, for example in the form of a half shell which can be joined together with the base part.  
         [0038]     In the case of a particularly preferred embodiment of the method according to the invention, it is provided that the preformed outer layer element and the base part are positioned in a receptacle of a mold and clamped to the mold by means of a clamping device. Subsequently, the liquid connecting material can be forced between the rear side of the outer layer element and the visible side of the base part. The mold may be adapted in a low-cost way to the three-dimensional surface shaping of the visible side of the outer layer element, so that the outer layer element can be supported over its surface area by the mold during clamping to the base part.  
         [0039]     It is of particular advantage if a UV-radiation-permeable mold is used, for example a glass or silicone mold, which preferably has a receptacle shaped in the form of a pan.  
         [0040]     A synthetic resin varnish is preferably used as the connecting material, especially a synthetic resin varnish which can be cured by means of UV radiation. This makes it possible to cure the connecting material within a short time, for example within less than around 3 minutes, while the outer layer element and the base part are clamped to the mold by means of the clamping device.  
         [0041]     According to an advantageous development of the method, it is provided that at least one decorative material, for example leaves, horn, sand, wood shavings or the like, is disposed between the outer layer element and the base part.  
         [0042]     Here it may be provided that the preformed outer layer element is in the first instance positioned in the receptacle of the mold, the decorative material is subsequently disposed on the rear side of the decorative layer element, in a further method step the base part is placed onto the decorative material and is then clamped to the outer layer element by means of the clamping device. In a subsequent method step, the connecting material in liquid form can then be forced between the outer layer element and the base part and be cured—preferably by means of UV radiation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0043]      FIG. 1  shows a base part clamped onto a deep drawing mold of a deep drawing installation;  
         [0044]      FIG. 2  shows the base part according to  FIG. 1  with the outer layer element drawn on;  
         [0045]      FIG. 3  shows the base part with the outer layer element drawn on according to  FIG. 2  when the connecting material is being introduced between the base part and the outer layer element;  
         [0046]      FIG. 4  shows the base part with the outer layer element drawn on according to  FIG. 2  when the connecting material is being cured;  
         [0047]      FIG. 5  shows a finished interior fitting according to a first embodiment of the invention;  
         [0048]      FIG. 6  shows an interior fitting according to a second embodiment of the invention when a connecting element is being cured and  
         [0049]      FIG. 7  shows the finished interior fitting according to  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0050]     In FIGS.  1  to  4 , four method steps for the production of an interior fitting according to a first embodiment of the invention, schematically represented in  FIG. 5 , are represented in a schematic representation.  
         [0051]     The interior fitting is designated in  FIG. 5  by the reference numeral  10  and comprises a base part  12 , which is coated on its visible side  13  by an outer layer element  14  in the form of a polycarbonate (PC) film around 0.4 mm to around 0.7 mm thick, with a connecting layer in the form of a layer of transparent varnish  16  being disposed between the PC film  14  and the visible side  13  of the base part  12 . On the rear side, the base part  12  carries holding parts in the form of latching elements  17 ,  18 , with the aid of which the internal fitting  10  can be fastened in the interior of a motor vehicle. The interior fitting  10  has a clearance  48  and, as a result, can be mounted for example on a control element of the motor vehicle.  
         [0052]     The base part  12  forms a decorative part and, in the exemplary embodiment represented, takes the form of a wood veneer part. However, it may also be provided for the base part to take the form of a metal part for example, especially an aluminum part, preferably a printed aluminum part. Furthermore, a leather part or a textile material stabilized on its rear side, for example a carbon fabric, may be used for example as the base part. It is also possible to combine a number of materials to form a base part. Furthermore, it may be provided for the base part to take the form of a rear part supporting the interior fitting on the rear side, which at most is given a secondary decorative function but, facing the outer layer element, receives an embellishing decorative material, as explained further below.  
         [0053]     Like the layer of varnish  16 , the PC film  14  takes a transparent form and is distinguished by especially high abrasion resistance. The layer of varnish  16  is produced from a synthetic resin, for example based on a polyester, polyurethane or acrylic- or epoxy-based. The layer of varnish  16  effects a sealing of the visible side  13  of the base part  12  and serves at the same time as a buffering layer, with the aid of which it is possible to compensate for the different thermal expansions of the base part  12  and the PC film  14 .  
         [0054]     The production of the interior fitting  10  is explained in more detail below with reference to FIGS.  1  to  4 . In a first method step, the preformed base part  12 , provided on the rear side with the latching elements  17  and  18 , is clamped onto a deep drawing mold  20  of a deep drawing installation, said mold being known per se and therefore only represented schematically in the drawing. The latter has a supporting surface  21 , which is adapted to the shape of the base part  12 , and, at a distance from the base part  12 , suction channels  22 ,  23 , which open out into the supporting surface  21 , are in flow connection with a suction source not represented in the drawing, for example a pump, and can be subjected to a negative pressure.  
         [0055]     In a second method step, schematically represented in  FIG. 2 , the PC film  14  is placed onto the visible side  13  of the base part  12 . The film  14  is chosen here to be larger than the visible side  13  of the base part  12 , so that it covers over the mouth regions  24  and  25  of the suction channels  22  and  23 . Subsequently, the suction channels  22  and  23  are subjected to negative pressure, so that the PC film  14  is drawn over the base part  12  on the visible side. The PC film  14  hereby adapts itself completely to the shape of the visible side  13  of the base part  12 .  
         [0056]     In a further method step, illustrated in  FIG. 3 , the base part  12  with the drawn-on PC film  14  is removed from the thermoforming mold  20  and clamped to a mold part  30  by means of a clamping device  28 . The mold part  30  comprises a carrying plate  32  made of a UV-radiation-permeable plastics or glass material, preferably quartz glass, which has only low absorption for ultraviolet (UV) radiation. The carrying plate  32  carries a mold  34 , which has on its side facing away from the carrying plate  32  a pan-shaped receptacle  35 , adapted to the shaping of the visible side  13  of the base part  12  covered with the PC film  14 . The mold  34  is likewise produced from a UV-radiation-permeable material, preferably from a silicone material.  
         [0057]     The clamping device  38  comprises a clamping lever  37 , from which there protrude in the direction of the carrying plate  32  a number of clamping pins  38 , which respectively carry at their free end a clamping plate  39 , which engages against the rear side of the base part  12 , so that the latter is held undisplaceably within the pan-shaped receptacle  35 .  
         [0058]     The base part  12  has a filling opening  41  passing through it, which is covered over on the visible side by the PC film  14 . A liquid synthetic resin varnish is injected into the region between the visible side  13  of the base part  12  and the PC film  14  via the filling opening  41  by means of a filling nozzle  43 . The synthetic resin varnish distributes itself over the entire visible side  13  of the base part  12  and subsequently—as represented in  FIG. 4 —can be cured by means of UV radiation  45 , which is provided by a UV radiation source  46  disposed underneath the carrying plate  32 .  
         [0059]     After the curing of the varnish, the base part  12  covered with the PC film  14  on the visible side can be removed from the mold part  30 . Further surface working of the interior fitting  10  to improve its surface quality is not required. In the case of the exemplary embodiment according to  FIG. 5 , it is merely provided that, after removal from the mold part  30 , the clearance  48  is introduced into the interior fitting  10 , for example by milling. The clearance  48  is disposed here in a region in which the filling opening  41  of the base part  12  was originally positioned. If no such clearance  48  is provided on the finished interior fitting  10 , the introduction of the varnish into the intermediate space between the visible side  13  of the base part  12  and the PC film  14  by means of the filling nozzle  43  can be performed in an edge region of the base part  12 , for example directly alongside a latching element  17  or  18 .  
         [0060]     A second embodiment of an interior fitting according to the invention is schematically represented in  FIG. 7 . It is designated overall by the reference numeral  50  and comprises a base part  51 , which in the exemplary embodiment represented is likewise produced using wood. While in the exemplary embodiment described above the base part is covered by an outer layer element in the form of a film of plastic  14 , the base part  51  of the interior fitting  50  is covered over on its visible side  52  by an outer layer element in the form of a front plastics shell  54 , formed as a prefabricated injection-molded part. Disposed on the rear side  56  of the base part  51  is a rear plastics shell  58 , which likewise takes the form of a prefabricated injection-molded part and forms a supporting element for the base part  51  and has on its outer side facing away from the rear side  56  formed-on latching elements  60 ,  61  and also a receptacle  62 , which receives a lighting element when the interior fitting  50  is fitted into the interior of a motor vehicle.  
         [0061]     The front plastics shell  54  and the rear plastics shell  58  form a housing completely surrounding the base part  51  and are respectively produced from a transparent plastic by the injection-molding process. Disposed between the plastics shells  54  and  58  on the one hand and the base part  51  on the other hand is a connecting layer, completely surrounding the base part  51 , in the form of a layer of varnish  64 , which likewise takes a transparent form and fixes the front plastics shell  54  and the rear plastics shell  58  on the base part  51 .  
         [0062]     Since the plastics shells  54  and  58  and the layer of varnish  64  are of a transparent form, the interior fitting  50  can be backlit in a simple way by means of the lighting element to be positioned in the receptacle  63 , so that the interior fitting  50  is distinguished by an esthetically especially pleasing configuration.  
         [0063]     The production of the interior fitting  50  is illustrated especially clearly by  FIG. 6 . In a way corresponding to the statements made with respect to  FIGS. 3 and 4 , in the production of the interior fitting  50  a mold part  66  is provided. This comprises an upper mold  68  and a lower mold  70 , which, facing each other, respectively have a dish-shaped receptacle  72  and  73 . The upper mold  68  and the lower mold  70  respectively comprise a mold  74  and  75  which is produced from a UV-radiation-permeable material, especially a silicone material, and into which the pan-shaped receptacles  72  and  73  have been introduced. The lower mold  70  also comprises a carrying plate  76 , which is produced from a UV-radiation-permeable material, especially from quartz glass, and supports the mold  75 . Positioned underneath the carrying plate  76  is a lower UV radiation source  77 .  
         [0064]     The upper mold  68  has on its upper side, facing away from the dish-shaped receptacle  72 , a top plate  79 , which is produced from a UV-radiation-permeable material, preferably from quartz glass. Disposed above the top plate  79  is an upper UV radiation source  80 .  
         [0065]     In a first method step, with the upper and lower molds  68 ,  70  still separated, the front plastics shell  54  of the interior component  50 , prefabricated by the injection-molding process, is introduced into the pan-shaped receptacle  73  of the lower mold  70 . Subsequently, the base part  51  is positioned in the plastics shell  54 . In a further method step, the rear plastics shell  58  is then placed onto the rear side of the base part  51 , and subsequently the mold part  66  is closed. Then, a liquid synthetic resin varnish is forced into the intermediate space between the base part  51  on the one hand and the front and rear plastics shells  54  and  58  on the other hand via a filling channel not represented in the drawing. The still liquid synthetic resin varnish here surrounds the base part  51  completely and is subsequently cured by being subjected on both sides to UV radiation within the mold part  66  by means of the lower radiation source  77  and the upper radiation source  80 . The cured layer of varnish  64  forms a connecting layer reliably connecting the plastics shells  54  and  58  on the base part  51  and also represents a buffer, with the aid of which it is possible to compensate for the different thermal expansions of the plastics shells  54  and  58  on the one hand and of the base part  51  on the other hand.  
         [0066]     The plastics shells  54  and  58  form a transparent covering for the base part  51 . This provides the possibility of disposing additional decorative materials between the base part  51  and the plastics shells  54  and  58 . For example, it may be provided that natural materials such as for example leaves, horn, sand etc. are positioned on the rear side of the front plastics shell  54 , facing the base part  51 , before the base part  51  is placed onto the front plastics shell  54 .  
         [0067]     Subsequently, as explained above, the varnish can be forced in, completely surrounding the decorative material, and then cured. As a result, the esthetic effect of the interior fitting  50  can be additionally improved.