Process for the forming of a covering element particularly for vehicle interiors and the covering element manufactured with said process

Abstract: The process for the forming of a covering element particularly for vehicle interiors consists in associating, by means of a preset pressure, a wooden plate-like element with a malleable support defined by at least one layer made of a fabric impregnated with a product based on epoxy resin; subsequently, during the application of the pressure, the assembly is heated to a preset temperature to give the wooden plate-like element and the support the pre-required configuration; the covering element obtained with the above process comprises a layer of wooden material (2) associated with a support (3) which is defined by at least one layer of fabric impregnated by a product based on epoxy resin.

Description: The present invention relates to a process for the forming of a covering element particularly for vehicle interiors and to the covering element manufactured with said process. As is known, mechanical means of transport are currently mainly made of plastic materials due to technical, economical and aesthetical reasons. The typical fundamental properties of plastic materials in general, i.e. the high ratio between mechanical strength and weight, impact strength, weatherability, resistance to chemical agents, almost nil electric conductivity, dimensional stability, ability to elastically absorb vibrations and consequent acoustic deadening, convertibility by means of rapid and precise mass-production processes, and aesthetics, have in fact made this type of material primarily important in the manufacture of mechanical means of transport. The interior of any vehicle, be it a motor vehicle, a ship, an aircraft, a train and the like, has furthermore currently assumed an importance which is as fundamental as that which derives from the technical characteristics of the means of transport. For example, in the field of car manufacturing, the aesthetics of the interior of a vehicle can even determine the choice thereof on the part of the buyer. Sometimes, however, the use of fine materials, such as for example wood or the like, for the covering of an interior of a vehicle poorly complies with the current need to manufacture vehicles having an extremely low weight, since the weight of the vehicle, the power of the engine, and therefore also the fuel consumption and the running costs per kilometer are generally closely interdependent. For example, in the case of seagoing transport, the weight indeed determines the displacement of the hull, and the resistance of water on the immersed parts mainly depends on the volume of displacement, which is indeed calculated by dividing the displacement in tons by the relative density of water. The problem worsens in aircraft, in which weight is the main force to be overcome for takeoff. Consequently, the materials which provide the finishing of the interior of a mechanical means of transport, in view of the above, must simultaneously have a low relative density and be aesthetically pleasant. One of the materials still currently most used for vehicle interiors is wood, and more precisely brier. In the field of car manufacturing, for example, brier, due to reasons of strength, is glued directly onto pre-shaped aluminum supports which are then associated with the vehicle. Besides the above, one of the main disadvantages, as regards for example the interior of a motor vehicle, is that the materials which constitute it must be able to withstand considerable temperature variations without problems, passing for example from temperatures below zero to much higher temperatures above zero, for example when the vehicle is left in the sun. In these operating conditions, since the thermal expansion of brier is considerably different from that of aluminum, the brier often tends to separate from the aluminum support or to crack, so that after a relatively short period of time the aesthetic appearance of said brier is completely and inexorably deteriorated. Aluminum furthermore obviously has a high purchase and processing cost. Aluminum, before being associated with the brier, must in fact be treated on its surface and requires, in order to give it a particular configuration, particular dies which have a high cost and the execution whereof is justified only for mass-productions. Not least disadvantage of aluminum is also that, despite being one of the lightest metallic materials, its weight penalizes, if used massively, the lightness of the vehicle. Document FR-A-2 563 153 discloses a process for forming a covering element, particularly for vehicle interiors, and a covering element produced by the process, wherein a fabric impregnated with a suitable resin is bonded under heat and pressure in a single step to, inter alia, a wooden plate-like element. Essential for this document is that the resin penentrates the pores of the wooden plate-like element, to perform the 'hooking' of the wooden plate-like element to the fabric by drying of the resin. If the resin, however, penetrates into the pores of the wooden plate-like element, operations such as bleaching of said wooden element, after its connection with the fabric support, are hindered. In this situation, the technical aim of the present invention is to solve the above described problems of the known art. Within the scope of this technical aim, an important object of the present invention is to provide a process for the forming of a covering element particularly for vehicle interiors and a covering element manufactured with said process which is insensitive to even large temperature variations and has a high ratio between mechanical strength and weight. Another important object of the present invention is to provide a process for the forming of a covering element particularly for vehicle interiors and a covering element manufactured with said process which has high impact strength, weatherability and resistance to chemical agents, and also has an almost nil electric conductivity, has dimensional stability and an ability to elastically absorb vibrations, with the consequent acoustic deadening (these being extremely important factors in a means of transport). Not least object of the present invention is to provide a process for the forming of a covering element particularly for vehicle interiors and a covering element manufactured with said process which can be easily shaped by means of rapid and precise mass-production treatments and has an extremely pleasant and valid aesthetics. This aim, these objects and others are achieved by a process for the forming of a covering element particularly for vehicle interiors, in accordance with independent Claim 1. The covering element particularly for vehicle interiors obtained by means of the above process is a covering element in accordance with independent Claim 9. Further characteristics and advantages of the invention will become apparent with the description of a preferred but not exclusive embodiment of a process for the forming of a covering element particularly for vehicle interiors and of a covering element manufactured with said process, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a schematic perspective view of an interior of a motor vehicle which has brier covering elements executed according to the invention; Figure 2 is a sectional view, taken along the line II-II, of a covering element according to the invention; and Figure 3 is a sectional view of a panel with an aluminum support in which a layer of fabric impregnated with epoxy resin is interposed between the wood and the aluminum. With reference to the above figures, the process according to the invention is performed by means of the following succession of steps. A woven or non-woven fabric, for example made of glass fiber or cotton, defined by one or more layers, is prepared initially, and each layer is individually impregnated with a product based on epoxy resin. In particular, said epoxy resin-based product is composed of liquid epoxy resin which has an average relative molecular mass equal to 400 in a percentage substantially equal to 10%; of solid epoxy resin having an average relative molecular mass equal to 800 in a percentage substantially equal to 10%; of a hardness regulator defined by a trifunctional or tetrafunctional epoxy resin in a percentage substantially equal to 75%; and of a reaction catalyst which is present in a percentage substantially equal to 5%. Generally, the amount of epoxy resin-based product which is used per amount of fabric to be impregnated is substantially comprised between 200 and 400 g/m² for glass fiber fabric and non-woven fabric and between 90 and 250 g/m² for cotton fabric. Once the various layers are fully impregnated with the epoxy resin-based product, they are passed in an oven which progressively raises them from ambient temperature to a temperature close to 100 °C for a time substantially equal to approximately 3 minutes. Obviously, both the temperature and the time are variable according to the percentages of the components used. When it leaves the oven, the supporting element defined by one or more layers of glass fiber or cotton fabric or non-woven fabric impregnated with an epoxy-resin based product is dry but very malleable according to the percentages of the components used, so that once it has been associated with the brier plate-like element it can assume the pre-required shape simultaneously therewith during its permanence in the press. In particular, once the malleable supporting element has left the oven, the wooden plate-like element is associated therewith and a gradual pressure, which can vary from 49.035 to 784.56 kPa (0.5 to 8 kg per square centimeter), is applied to both for a preset time at a high temperature comprised between 120 and 180 °C. In this manner one obtains an element which has brier on its surface and is therefore aesthetically pleasant and has a support with such strength and rigidity characteristics as to favor its application inside mechanical means of transport, coverings of interior decoration articles, pieces of furniture and anything which can be covered. In particular, the basic characteristics of the brier covering element thus obtained are its light weight and its already mentioned chemical-physical properties. Furthermore, by means of the above described process, as can be easily understood, it is possible to give the brier plate-like element practically any configuration, even one having extremely small bending angles, without the brier having all the disadvantages, such as for example cracks, breakages or splinterings, which are produced by the method used so far. Essentially, it is possible to state that the brier and the epoxy resin form a unit, i.e. a monolithic body which is even better, from the physical-mechanical point of view, with respect to a solid high-thickness brier element, and can be shaped in any manner even with extremely small bending radii. The covering element executed with said process according to the invention, shown in Figure 2, is generally indicated by the reference numeral 1. As can be seen, the covering element mainly usable for interiors of means of transport comprises a layer of wooden material 2, for example brier, which is indissolubly associated with a support which is defined by at least one, and in particular a plurality of, layers of woven or non-woven fabric 3 impregnated by a product based on epoxy resin. In particular, as already mentioned, the epoxy resin-based product is defined by a liquid epoxy resin and by a solid epoxy resin, which have an average relative molecular mass equal to 400 and 800 respectively, by a hardness regulator defined by a trifunctional or tetrafunctional epoxy resin, and by a reaction catalyst. In a constructive variated embodiment, as illustrated in Figure 3, in replacement of the support defined by glass fiber or cotton fabric it is possible to apply the resin for example on a metallic material 4 such as aluminum. In this constructive variated embodiment, in order to prevent the brier from tending to break or splinter, due to its different thermal expansion with respect to the aluminum, a layer defined by a polyester fabric 5, again impregnated with an epoxy resin-based product as described above, is interposed between said two elements. Obviously, the percentages of the liquid epoxy resin, of the solid epoxy resin, of the hardness regulator and of the reaction catalyst will vary in the epoxy resin-based product of this last solution and will be approximately 30%, substantially 5%, approximately 60% and approximately 5% respectively. In this case also, in which aluminum is used as main supporting element, the polyester fabric which is impregnated with epoxy resin-based product is passed in an oven at a temperature close to 100 °C for approximately 4 minutes, and the amount of epoxy resin-based product is substantially equal to 120 grams per square meter. In this case, the pressure and temperature used during the pressing of the aluminum simultaneously with the brier plate-like element are substantially equal to those mentioned for glass fiber or cotton fabric. The invention achieves the proposed aim and objects and furthermore achieves important and numerous advantages. Among these, it should be mentioned that besides the extremely valid aesthetic appearance of the brier and the extremely low cost of the panel or covering element obtained, one achieves a high ratio between mechanical strength and weight, impact strength, weatherability and resistance to chemical agents, almost nil electric conductivity, dimensional stability, ability to elastically absorb vibrations with consequent acoustic deadening, which make the product according to the invention extremely suitable for the current requirements for the finishing or manufacture of interiors of means of transport or of any type of covering. The process and the covering element which form the subject of the invention can furthermore be advantageous even and most of all for small production runs.

Claims: Process for forming a covering element, particularly for vehicle interiors, which consists in: impregnating a woven or non-woven fabric with an epoxy resin based product; drying said impregnated fabric in an oven at a first predetermined temperature and for a period sufficient to form a dry and malleable support; applying a wooden plate-like element to said support and shaping said support together with the wooden plate-like element by pressing said plate-like element against said support at a preset pressure and simultaneously heating, for a preset time, at a temperature which is substantially higher than said first temperature to form said covering element with a given configuration and with a required rigidity and said plate-like element bonded to said support to impart a wood aesthetic appearance thereto. Process according to claim 1, characterized in that said fabric is made of glass fiber and is defined by one or more individually impregnated layers. Process according to claim 1, characterized in that said fabric is made of cotton and is defined by one or more individually impregnated layers. Process according to claim 1, characterized in that said epoxy resin-based product comprises a percentage of a liquid epoxy resin, a percentage of a solid epoxy resin, a hardness regulator and a reaction catalyst. Process according to claim 1, characterized in that the heating temperature in the oven is comprised between 80 and 110 °C. Process according to claim 1, characterized in that said fabric is impregnated with said epoxy-resin product in an amount comprised between 80 and 220 g/m². Process according to claim 1, characterized in that in the shaping step the pressure is comprised between 49.035 to 784.56 kPa(0.5 and 8 kg/cm².) and the temperature is comprised between 120 and 180 °C. Process according to claim 4, characterized in that said liquid epoxy resin has an average relative molecular mass equal to 400 and that said solid epoxy resin has an average relative molecular mass equal to 800. Covering element, particularly for vehicle interiors, comprising a layer of wooden material (2) associated with a support which is defined by at-least one layer of woven or non-woven fabric (3) impregnated by a product based on epoxy resin, characterized in that said epoxy resin-based product comprises a liquid epoxy resin which has an average relative molecular mass equal to 400, a solid epoxy resin which has an average relative molecular mass equal to 800, a hardness regulator and a reaction catalyst. Covering element according to claim 9, characterized in that said layer made of wooden material is made of brier. Covering element according to claim 9, characterized in that said product comprises a percentage of liquid epoxy resin comprised between 5% and 15%, a percentage of solid epoxy resin which is substantially equal to that of said liquid epoxy resin, a percentage of hardness regulator comprised between 60% and 90%, and a percentage of reaction catalyst comprised between 2% and 8%.

Inventors: ABELTINO ETTORE, ABELTINO, ETTORE
Applicants: ORDINAN TRADING LTD
Application year: 1991
Main classification: B32B21
IPC codes: B32B17, B60R13, B32B37, B32B27, B32B21