Usual household appliances such as washing machines and dishwashers are generally received into a housing having at the upper side a covering top panel serving as both attractive furnishing member and support surface for the user.

In addition to aesthetical features the top panel should also have a particular mechanical sturdiness for supporting weights without giving way because of loads as well as a perfect straightforwardness of its dimensions to cover the housing completely.

Usual top panels consist presently of chipboard panels with surfaces faced by laminated plastic sheets that protect the chipboard top panel from deterioration and improve the design of the product. The top board is fitted into a frame and forms the support surface to which fasteners and support members of the top panel of the household appliance housing can be secured. Then ^' the top board is glued to the frame by a sealing adhesive seam that is spread along the periphery of the lower surface of the top board and enters the edges of the latter between frame and fasteners so as to glue and to secure the above- mentioned portions and to provide a fluid-tight sealing. The board represents specifically the basis of the top panel as it is the main component featuring the

aesthetics of the whole assembly. In fact the coating laminated sheet of polymer material applied to the raw chipboard protects the latter against the deterioration of the wood and is just used to give it an optimum surface finishing with a colouring which is comparable with its frame and essentially the same as the colour of the whole household appliance. It provides a support surface for the user and should then have a good resistance to bending stress. Presently the board is produced from chipboard sheets of about 10 square meters which are faced with melanin sheets and then cut into boards with suitable size according to the several sizes of the top panels for household appliances. This production method produces wooden shavings due to the cutting of the sheet that cannot be used for the assembling and then discarded. ϋnevenness in the fixed dimensions of the board occurs just during the cutting step, which causes a size unevenness and big problems during assembling. Moreover, there is a restraint in the thickness that should be standardized like the commercial chipboard sheets, i.e. 5, 10, 20 mm. Furthermore, top panel manufacturers have to stock up with a large quantity of panels that should be enough for the production of all top panel sizes so that stocking and storing problems arise due to fire prevention and the hygroscopic nature of the material that can make it useless. The present industrial invention relates to a new

method of producing a board for the covering top panel by using a new material that will bring significant advantages to the top panel manufacturers with the capability for the product of being recycled. As stated above, the board of the state of art consists of pressed chipboard covered by a laminated polymer film.

The invention relates to a method of providing a board by injection moulding having a greater resistance to bending stress than the chipboard wooden panels, a dimension stability ensured both by the composition of the new material and the moulding system and a capability of being recycled as well as the same compact, warm appearance for the user as the wood. The new board consists of a composite material containing wood and natural components such as corn, bran, oath, etc. giving a neutral coloration and an optimum surface finishing as well as an amount of polymer material giving it sturdiness and an amount of additives giving it a wide range of colours.

The novelty brought by these composite materials combines the positive features of the wood with the fully working flexibility required by the plastic material manufacturing industry, thus allowing such composite materials to be transformed into a fibrous material to manufacture novel products with' ' high quality.

The raw material used consists of natural, biological fibres such as wood, rice or coconut wool fibres forming the main components.

Therefore, the raw materials of the board are ecologically bearable.

The board thus obtained has a greater quality and is stable and innovative. One peculiar feature of this composite material that makes it able to be used for the manufacturing of boards for top panels is that the wooden components and natural fibre additives give the material an extremely low shrinkage and guarantee an incomparable dimension stability as the firm structure of the fibres does not allow the macromolecules of the polymer to be relocated during cooling, thus blocking the dimensions achieved during the injection moulding. The polymer entering the interstices of the wood reticule gives the composite material a lower density and a far greater mechanical resistance than the wood as the empty intermolecular spaces of the wood are occupied by polymer components, thus allowing the thickness to be reduced and the inside of the board to be blow moulded as well as keeping its features and properties unchanged. The structure with reduced thickness could at most be reinforced by ribbings to bear the load lying on the top panel. The wood fibres acting as filler produces a very low shrinkage of the product.

Furthermore, as the board is manufactured by injection moulding, i.e. by means of a die, the provision of suitable shaping die inserts allows the requested size for the several board designs to be obtained both as regarding to the thickness and the other dimensions,

no restriction relative to the standard size of the wooden boards being provided for fitter and designer. The equipment for the production of the board is an injection moulding screw press having a screw which is particularly designed to process the composite material and is provided with a degassing system that allows the residual gases to be vented.

This process is based on a particular moulding cycle. In fact, after the injection of the melted material into the closed die, the latter is opened by a few millimetres to allow the inside gases to be vented and then closed again to allow an uniform stretching of the molecular polymer chains that are being formed, thus providing a perfect uniformity of the structure from the surface to the core of the board.

These composite materials have an inside humidity of about 5%, which would produce a poor surface quality of the board because a portion of the residual humidity would be released after the injection moulding during cooling, thus forming blowholes and porous areas.

Therefore, to improve the surface quality it is necessary to place the material in driers for about 12 hours to disperse the humidity until about 0.9%, a value that can then be vented by the degassing system of the press.

The process temperature ranges from 170 ⁰ C to 19O ⁰ C as higher temperature would deteriorate the wooden component of the composite material. The injection pressure is about 1900 bar, i.e. higher

than common PP, because of the fibrous particulate component of the melted material, however, with cycle time being reduced by 40% for the same product. After all, this method allows the board for a covering top panel hitherto made by wood to be manufactured by a composite material processed by an easy method allowing a quick production, a capability for the material to be fully recycled, a dimension stability, optimum mechanical features, perfect straightforwardness, optimum surface quality, and a manufacturing in the strictly necessary amount for the volume of production in the assembling locations, thus avoiding storage and stocking of the boards that are produced in several sizes different from the standard size to which the today production processes of wooden boards are bound so that the boards of the invention can be used for assembling any covering top panels. Moreover the method of the invention allows the board to be produced together with the frame by a double injection method.

This method further allows thermoplastic rubber to be injected into a second die by double injection so as to cover the periphery of the board and to perform seaming and sealing functions. The moulding of the frame around the sheet avoids the use of seaming and sealing glues and adhesives between frame and board.

Furthermore, the boards can be seamed to the frame of the top panel by moulding neoprene gasket or connected thereto by vibration welding processes.

Technical, formal changes can be made to the present inventive solution without departing from the scope of the present industrial invention as defined in the appended claims.