The present invention concerns a method for manufacturing laminate constructions.

More particularly, the present invention concerns a method for manufacturing laminate constructions such as those which are usually used for the inside trim of a car interior.

Such laminate constructions are generally realised by taking a core as a basis, for example polyurethane foam, whereby a wire cloth or a fibre mat is applied on both sides of the core.

These wire cloths or fibre mats are laminated against the above-mentioned polyurethane foam by means of films or powders which can be thermally activated.

A disadvantage of this method is that the plate-shaped core with the wire cloths or fibre mats applied on it must be laminated one after the other in a press, as a result of which the whole process is slowed down.

According to an alternative known method, the wire cloths or fibre mats are connected to the plate-shaped base layers by applying special glues or films which can be thermally activated between the core and the wire cloths or fibre mats and by putting the different materials on top of each other in a heated mould, whereby the different layers are fastened and given the required shape in a single movement.

This known method combines two operations indeed, but it is still disadvantageous in that the process takes place in a discontinuous manner.

According to another known method, the laminate constructions are realised by mixing polypropylene and glass fibres, and by casting this mixture on an endless belt to subsequently dry the thus formed layer by means of hot air. The thus formed layer is simultaneously provided with a thin adhesive film or a screening layer of fibres on both sides which is fastened to the core by leading the whole between two pressure rollers, whereby the intermediate layer is simultaneously compressed.

The latter method is disadvantageous in that the thus obtained laminate constructions are relatively heavy, as the core must be strongly compressed to obtain the necessary stiffness, more particularly as the stiffness is not considerably raised by applying the above-mentioned thin adhesive film or screening layer of fibres.

The present invention aims to remedy the above-mentioned and other disadvantages.

To this end, the invention concerns a method for realising laminate constructions, whereby a core is taken as a basis which is mainly made of a thermoplastic material, for example polyalkene, polyamide or polyester; whereby a layer reinforced with fibres is applied on at least one side of this core, which is composed of at least one layer of fibres provided with a layer of polymer on both sides, such as for example polypropylene or polyethylene ; whereby the core and the layer reinforced with fibres, layers respectively, provided on it are then compressed ; whereby

the above-mentioned steps are carried out in a continuous manner and during the production process of the core.

An advantage of this method according to the invention is that the entire method is carried out in a continuous and consequently also a fast manner.

Another advantage of the method according to the invention is that such layers reinforced with fibres influence the rigidity in a positive manner, such that the core can be made very light and with good insulating qualities.

The fact that the core can be made light moreover implies an even faster production process.

According to another application, at least one of the above-mentioned layers reinforced with fibres is provided with an adhesive layer on its outer side which can be activated.

The advantage which is thus obtained is that the thus obtained laminate construction is already provided with an adhesive layer by means of which, in a later stage, a decorative layer or any other layer whatsoever can be connected to the laminate construction.

According to another preferred embodiment, at least one of the above-mentioned layers reinforced with fibres are provided with an extra layer of fibres on its outside which protects the fibres of the core against tears and as a result of which the layer reinforced with fibres obtains soft and dampening qualities, as a result of which any possible vibrations are dampened.

According to another embodiment, at least one of the above- mentioned layers reinforced with fibres are perforated before applying them to the core, as a result of which is obtained that the sound-damping characteristics of the laminate construction are much improved.

According to a special embodiment, the core is compressed between the pressure rollers together with the layers reinforced with fibres, whereby the layers which are reinforced with fibres are fastened against the core, and whereby the core is simultaneously compressed up to a controlled thickness.

The advantage is that the bond to the core of the layers reinforced with fibres is combined in a single motion with the controlled adjusting of the thickness of the laminate construction.

According to a special embodiment, the core is made by mixing a polymer with fibres; by subsequently applying this mixture in a viscous layer on an endless belt and by then leading this layer along a drying installation.

According to an alternative embodiment, the core is made by extruding a thermoplastic material, for example polyalkene, polyamide or polyester. If necessary, foam additives will be added, such that an extruded foam is obtained.

In order to better explain the characteristics of the invention, the following preferred application of the method for realising laminate constructions according to the invention is described as an example only without being limitative in any way, with reference to the accompanying drawings, in which:

figure 1 schematically represents a device which makes it possible to realise the method according to the invention; figure 2 represents the part indicated by F2 in figure 1 to a larger scale.

Figure 1 represents a flask 1 which contains a mixture of a thermoplastic material, for example polypropylene, and additives, and next to it a flask 2 containing cut-up fibres.

At the bottom of the flasks 1 and 2 are provided pipes 3 leading into a mixer installation 4, whereby the latter is in turn provided with a pipe 5 at the bottom which opens at the top of a distributing basin 6.

This distributing basin 6 is provided at the top of an endless belt 7 which is made of a porous material and which is provided clockwise around two return pulleys, 8 and 9 respectively, whereby the return pulley 8 functions as a drive wheel, whereas the return pulley 9 functions as a pressure roller.

Between the distributing basin 6 and the above-mentioned return pulley 9 is provided a vacuum device 10 on the one hand, more particularly just under the topmost part of the endless belt 7, and in the further course of the endless belt 7 is provided a drying installation 11 on the other hand, more particularly around the top part of the endless belt 7, through which the endless belt 7 runs.

Above the return pulley 9 is provided a pressure roller 12, whereby the distance between the return pulley 9 and the pressure roller 12 can be adjusted in a suitable manner which is not represented in the drawings.

Under the return pulley 9 is provided a bobbin 13 which is equipped with a mat 14 reinforced with fibres, which consists of a layer of fibres 15 of which each side is provided with a layer of polymer 16, for example polypropylene, and whereby one of these layers of polymer 16 is provided with a second layer of fibres 17.

Above the pressure roller 12 is provided a bobbin 18 which is also equipped with a mat 19 reinforced with fibres, which consists of a layer of fibres 15 of which each side is provided with a layer of polymer 16, for example polypropylene, and whereby one of these layers of polymer 16 is provided with an adhesive layer 20 which can be activated, for example an adhesive layer which can be thermally activated.

Between the pressure roller 12 and the bobbin 18 is provided a perforator 21 which consists of a drum 22 provided with pointed protrusions 23.

In the extension of the endless belt 7 are provided guide rollers 24 and knives 25.

The device, as represented in figures 1 and 2, makes it possible to realise laminate constructions.

The mixture of the thermoplastic material, more particularly the polypropylene and the additives contained in the flask 1, and the cut-up fibres contained in the flask 2 are led into the mixer device 4 via the pipes 3, and they are mixed there until a viscous mixture 26 is obtained.

Via the pipe 5, this mixture is gradually poured in the distributing basin 6, which evenly distributes this viscous mixture 26, and at the required thickness, over the width of the endless belt 7.

On the bottom side of the endless belt 7 is created a vacuum by means of the vacuum device 10, such that the viscous layer 27 is sucked against the endless belt 7.

This vacuum prevents that the viscous layer 27 assumes an irregular and strongly expanded shape and it keeps the viscous layer 27 better in place.

The viscous layer 27 is moved by means of the endless belt 7 and led through the drying installation 11, where the viscous layer 27 is transformed into a core 28 which at that time consists of a layer of fibres bonded by the polymer, for example polypropylene.

Just before the return pulley 9 and the pressure roller 12 is provided the layer 14 reinforced with fibres on the bottom side of the core 28 as of the bobbin 13, whereby the second layer of fibres 16 is directed towards the free bottom side.

Simultaneously, the bobbin 18 is gradually unwound, and the layer 19 reinforced with fibres is guided along the perforator 21, where the pointed protrusions 23 pierce the layer 19 reinforced with fibres and provide the latter with holes 29.

Next, the layer 19 reinforced with fibres is provided against the top side of the core 28, whereby the adhesive layer 20 which can be activated is directed towards the free top side.

Immediately after the layers 14 and 19 reinforced with fibres have been applied against the core 28, the whole is led between the return pulley 9, which functions as a pressure roller, and the pressure roller 12, whereby the layers 14 and 19 reinforced with fibres are fastened to the core 28 in a single movement, and whereby the core 28 is compressed to a controlled thickness.

The bond is realised thanks to the chemical seal created under pressure between the polypropylene of the core 28 and the polymer of the layers 14 and 19 reinforced with fibres.

The core 28 must only be compressed to a limited extent thanks to the increased stiffness caused by the layers 14 and 19 reinforced with fibres, such that the core 28 stays light and strongly insulating, also after the compression.

Thus is obtained a laminate construction 30, consisting of a compressed core 28 with, on the bottom side, a layer 14 reinforced with fibres connected thereto provided with an outward directed second layer of fibres 17, and with a perforated layer 19 reinforced with fibres on the top side of the compressed core 28, provided with an outward directed adhesive layer 20 which can be activated.

The laminate construction 30 is then led between guiding rollers 24, after which the laminate construction 30 is cut off at fixed lengths by the knives 25. The thus obtained sheets 31 can be stacked on a pallet 32 if required.

Is it clear that the adhesive layer 20 which can be activated will only fulfil its task at a later stage, more particularly when a decorative layer or another layer is fastened to the laminate construction 30. At that time,

the adhesive layer 20 which can be activated is put into action, in the case of an adhesive layer which can be thermally activated by applying a raised temperature.

On the same side of the laminate construction 30 have been provided holes 29, more particularly to improve the sound- damping qualities.

On the other side of the laminate construction 30 has been provided a second layer of fibres 17 on the free outer side, which can be fixed for example against the inner wall of the roof of an automobile at a later stage.

It is clear that the layers 14 and 19 reinforced with fibres, which are being unwound from the bobbins 13 and 18 in figure 1, can also be produced simultaneously and can be provided directly, i. e. without winding them on bobbins first.

Conversely, it is also possible, if the sound-damping holes 29 are required, to provide them immediately after the layer 19 reinforced with fibres has been produced and before it is wound on a bobbin 18.

It is clear that the core can be made of other materials, as long as the main component is a thermoplastic material, such as for example polyalkene, polyamide or polyester.

It is clear that the core 28 can be realised in various manners while still remaining within the scope of the invention, such as for example by extruding a thermoplastic material, for example polyalkene, polyamide or polyester.

It is also clear that foam additives can be added before or during the extrusion process, such that a core 28 of extruded foam is obtained.

The present invention is by no means limited to the above- described method given as an example; on the contrary, it can be realised in all sorts of variants while still remaining within the scope of the invention.