The present invention relates to shaped plastic building panels, in particular roof panels, wall panels, floor panels and the like.

Such shaped plastic roof panels may more specifically consist of panels which take the appearance of a set of roof tiles or roof shingles ; such shaped wall panels may more specifically consist of panels that take the appearance of brick walls or shingle wall coverings (in particular for use on external walls of buildings, or on internal walls or as internal walls) ; such shaped floor panels may more specifically take the appearance of wood flooring, stone flooring, concrete etc..

For producing small size decorative building panels, use has been made of conventional moulding techniques.

These techniques are however not suited for producing large size building panels (such as panels exceeding 1 m ² ); for the production of such larger shaped panels the technique of vacuum forming of extruded plastic sheets has been proposed. Due to the separate process steps of extrusion and subsequent vacuum forming, this technique is very labour intensive and energy consuming, and therefore rather expensive.

The objective of the present invention is to provide an improved method for producing shaped building panels having sizes larger than 1 m ² and even larger than 2 m ² , thus providing less expensive shaped building panels which, very surprisingly, at the same time, involve considerably improved strength properties, visual properties and quality properties.

This objective of the invention is achieved by a method for manufacturing shaped, and optionally textured, plastic building panels, according to which

the panels are produced from a plasticized thermoplastic composition comprising PP material, HDPE material, mixtures of PP and HDPE material, or PET material, by direct transfer moulding of the plasticized thermoplastic material to a panel having the desired shape.

Techniques for the production of large size objects and parts by transfer moulding, involve that the plasticized thermoplastic material mass is conveyed according to an essentially rectilinear path towards the injection zone of the moulding process, more particularly to an injection piston co- operating with a hydraulically operated (semi-closed) mould, which rectilinear path may in particular comprise a shredder / mixer - conveyor for the thermoplastic materials and additives (such as fibers, fillers, etc). Equipment's for carrying out such techniques are for instance disclosed in the German patent publication DE 198 03 422 and in the European patent publication EP 1 263 562. Such equipment's (and similar machines as marketed by REMAPLAN ANLAGEBAU GMBH for the "injection- compression process" and the processing of plastic waste materials) are well suited for performing the method according to the invention.

According to a preferred further feature of the invention, the thermoplastic materials are plasticised, homogenised and/or conveyed towards the transfer moulding step by means of an extruder.

In a preferred embodiment of the invention, the method is carried out with a thermoplastic composition comprising 60-90% by weight of PP material and 10-40% by weight of HDPE material, which is shaped to a building panel by transfer moulding.

According to this embodiment of the invention the thermoplastic composition is preferably processed by means of a single screw extruder.

In another preferred embodiment of the invention, the method is carried out with a thermoplastic composition comprising at least 90% by weigt of PET material, which is shaped to a building panel by transfer moulding. According to this embodiment of the invention, the thermoplastic composition is preferably processed by means of a double screw extruder.

According to a further preferred feature of the invention, the panels are produced from a plasticized thermoplastic composition comprising at least 50% by weight of recycled plastic materials.

According to the invention the various materials leading to the plasticized thermoplastic composition involved in the direct transfer moulding process of the method, can be fed as raw materials into a feeder / mixing unit, without previous compounding thereof. Plastic waste materials of almost any type (sheets, films, relatively large plastic parts and/or rough cuttings), additives (plasticizers, stabilisers, etc.), fibres, fillers, pigments, etc., can thus be fed / dosed, directly into the feeder / mixing unit, through or in a shredder unit, which may contribute to the plasticizing of the material mixture,

According to still a further feature of the invention, subsequent to the transfer moulding step the panels are provided, in a so called "granulation stage" with a rugosity surface layer ("grit layer") consisting of stone grit, fine gravel, sand, pebble work, or the like.

The invention thus specifically covers the principle of using direct transfer moulding technology for manufacturing shaped, and optionally textured, plastic building panels, by processing a plasticized thermoplastic composition comprising PP material, HDPE material, mixtures of PP and HDPE material, or PET material, in particular under the conditions and circumstances set forth here above,

as well as any shaped, and optionally textured, plastic building panels, made of a thermoplastic material comprising PP, HDPE, mixtures of PP and HDPE, or PET, as obtained by direct transfer moulding of the thermoplastic material, or specifically involving such properties as obtainable by direct transfer moulding, and more in particular by using the direct transfer moulding method conditions as set forth here above.

Many modifications to the general principle of the invention will easily be conceived by those skilled in the art, without departing from the essence thereof as set forth in the above description and in the enclosed set of claims.

It will thus be readily understood that the construction panels according to the invention can be made in any kind of shape and/or appearance, merely by properly adapting the shape of the mould and/or by properly selecting the additives, pigments, fillers, etc. and/or by properly designing the surface post-treatment of the panels.