Method for manufacturing a panel including a reinforcement sheet, and a floor panel

Abstract

A method for manufacturing a panel including a reinforcement sheet having the steps of: providing a first layer of thermoplastic material, providing a reinforcement sheet, laying the reinforcement sheet and the first layer onto each other, applying a second layer of thermoplastic material on top of the reinforcement sheet at a side facing away from the first layer, at least partially melting the thermoplastic materials of the first layer and the second layer, adhering the at least partially melted first layer, the at least partially melted second layer and the reinforcement sheet to each other so as to form the panel. Additionally, the reinforcement sheet and the first layer are adhered to each other by pressing them together after at least partially melting the thermoplastic material of the first layer, but before applying the second layer of thermoplastic material onto the reinforcement sheet.

Claims

1. A method for manufacturing a panel including a reinforcement sheet, comprising the steps of: providing a first layer of thermoplastic material, providing a reinforcement sheet having a thickness, providing a second layer of thermoplastic material, combining the reinforcement sheet and the first layer by laying the reinforcement sheet on the first layer, or alternatively, by performing the step of providing the first layer of thermoplastic material by applying the thermoplastic material of the first layer onto the reinforcement sheet, after the step of combining the reinforcement sheet and the first layer, applying the second layer of thermoplastic material onto the reinforcement sheet at a side of the reinforcement sheet facing away from the first layer, at least partially melting the thermoplastic material of the first layer to form an at least partially melted first layer, at least partially melting the thermoplastic material of the second layer to form an at least partially melted second layer, adhering the at least partially melted first layer, the at least partially melted second layer and the reinforcement sheet to each other so as to form the panel, wherein the reinforcement sheet and the first layer are adhered to each other by pressing them together after the step of at least partially melting the thermoplastic material of the first layer, wherein an applied pressure during the step of pressing the reinforcement sheet and the first layer together and a rate of melting the thermoplastic material of the first layer during the step of at least partially melting the thermoplastic material of the first layer are selected such that the reinforcement sheet is impregnated by the thermoplastic material of the first layer over at least 80% of its thickness, wherein the step of providing the first layer of thermoplastic material comprises spreading granular thermoplastic material prior to the step of at least partially melting the thermoplastic material of the first layer, wherein the step of providing the second layer of thermoplastic material comprises providing the second layer in the form of a sheet or a film, and wherein the reinforcement sheet and the second layer are adhered to each other after the step of at least partially melting the thermoplastic material of the second layer, while the thermoplastic material of the second layer is still at least partially melted, and separately from the step of pressing the reinforcement sheet and the first layer together, by pressing the at least partially melted second layer onto the reinforcement sheet, wherein, in the panel, a thickness of the first layer is between 1 and 3.5 mm and the reinforcement sheet is located at a middle of the panel in a thickness direction or at a position in the thickness direction other than the middle, and wherein the panel has a total product thickness between 1.5 and 6.5 mm.

2. The method of claim 1, wherein the method is performed as a continuous process.

3. The method of claim 2, wherein the reinforcement sheet and the first layer are pressed together with a double belt press in the step of pressing the reinforcement sheet and the first layer together.

4. The method of claim 3, wherein pressing the second layer of at least partially melted thermoplastic material onto the reinforcement sheet is comprises calendering the second layer of at least partially melted thermoplastic material onto the reinforcement sheet.

5. The method of claim 4, wherein the step of calendering is performed with a calendering device which comprises more than two calendering rolls.

6. The method of claim 1, wherein the reinforcement sheet comprises a glass fiber foil.

7. The method of claim 6, wherein the glass fiber foil has a basis weight of 25-70 g/m.sup.2.

8. The method of claim 1, wherein the thermoplastic material of the first layer and the thermoplastic material of the second layer are the same.

9. The method of claim 1, wherein the reinforcement sheet is placed on top of the first layer before the step of pressing them together.

10. The method of claim 1, wherein the step of applying the second layer comprises applying the second layer on top of the reinforcement sheet.

11. The method of claim 1, wherein the first layer of thermoplastic material is made of semi rigid PVC containing at least 35% of inorganic fillers.

12. The method of claim 1, wherein the thermoplastic material of the first layer is provided in the form of granules having a cylindrical shape with a cylinder diameter in the range of 2.5-3.5 mm and a cylinder height in the range of 0.2-2.0 mm.

13. The method of claim 12, wherein the cylinder height is 0.5 mm.

14. The method of claim 1, further comprising a step of cooling the first layer of thermoplastic material and the reinforcement sheet before the step of applying the second layer of thermoplastic material onto the reinforcement sheet.

15. The method of claim 1, wherein: the step of combining the reinforcement sheet and the first layer comprises placing the reinforcement sheet on a lower press plate or press member and spreading granules of the thermoplastic material of the first layer over the reinforcement sheet before the step of pressing the reinforcement sheet and the first layer together, and the method further includes a step of turning the reinforcement sheet and the first layer upside down before the step of applying the second layer of thermoplastic material onto the reinforcement sheet.

16. A method for manufacturing a panel including a reinforcement sheet, consisting of the steps of: providing a first layer of thermoplastic material, providing a reinforcement sheet having a thickness, providing a second layer of thermoplastic material, combining the reinforcement sheet and the first layer by laying the reinforcement sheet on the first layer, or alternatively, by performing the step of providing the first layer of thermoplastic material by applying the thermoplastic material of the first layer onto the reinforcement sheet, after the step of combining the reinforcement sheet and the first layer, applying the second layer of thermoplastic material onto the reinforcement sheet at a side of the reinforcement sheet facing away from the first layer, at least partially melting the thermoplastic material of the first layer to form an at least partially melted first layer, at least partially melting the thermoplastic material of the second layer to form an at least partially melted second layer, adhering the at least partially melted first layer, the at least partially melted second layer and the reinforcement sheet to each other so as to form the panel, wherein the reinforcement sheet and the first layer are adhered to each other by pressing them together after the step of at least partially melting the thermoplastic material of the first layer, wherein an applied pressure during the step of pressing the reinforcement sheet and the first layer together and a rate of melting the thermoplastic material of the first layer during the step of at least partially melting the thermoplastic material of the first layer are selected such that the reinforcement sheet is impregnated by the thermoplastic material of the first layer over at least 80% of its thickness, wherein the step of providing the first layer of thermoplastic material comprises spreading granular thermoplastic material prior to the step of at least partially melting the thermoplastic material of the first layer, wherein the step of providing the second layer of thermoplastic material comprises providing the second layer in the form of a sheet or a film, and wherein the reinforcement sheet and the second layer are adhered to each other after the step of at least partially melting the thermoplastic material of the second layer, while the thermoplastic material of the second layer is still at least partially melted, and separately from the step of pressing the reinforcement sheet and the first layer together, by pressing the at least partially melted second layer onto the reinforcement sheet.

17. The method of claim 16, wherein, in the panel, a thickness of the first layer is between 1 and 3.5 mm and the reinforcement sheet is located at middle of the panel in a thickness direction or at a position in the thickness direction other than the middle.

18. The method of claim 17, wherein the panel has a total product thickness between 1.5 and 6.5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will hereafter be elucidated with reference to a very schematic drawing showing an embodiment of the invention by way of example.

(2) FIG. 1 is an illustrative side view of an apparatus for performing an embodiment of the method for manufacturing a panel according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) FIG. 1 shows a part of an apparatus 1 for continuously processing a web and illustrates some steps of an embodiment of a method for manufacturing a panel including a reinforcement sheet according to the invention. The apparatus 1 includes a granulate supply 2 which is adapted to supply a first layer or base layer 3 of granulate on a supporting lower conveyor belt 4. The lower conveyor belt 4 is an endless belt. The granulate is spread evenly on the lower conveyor belt 4. The granulate is made from a thermoplastic material, for example flexible PVC.

(4) The lower conveyor belt 4 has a greater length than a second, upper endless conveyor belt 5 which is positioned at a distance downstream of the granulate supply 2 and runs along a part of the lower conveyor belt 4. At the upper portion of the lower conveyor belt 4, both conveyor belts 4, 5 run in the same manufacturing direction, in FIG. 1 from left to right as indicated by an arrow at the lower conveyor belt 4.

(5) There is supplied a reinforcement sheet 6 on top of the base layer 3 of granulate. The reinforcement sheet 6 may be a glass fibre foil or any alternative foil which has reinforcement properties. The reinforcement sheet 6 is supplied by unwinding it from a supply roll 7. Subsequently, the reinforcement sheet 6 and the base layer 3 of granulate are transported between the lower and upper conveyor belts 4, 5 along a heating device 8 in order to melt the base layer 3 of granulates, and then pressed together by a pressing unit 9. The rate of melting may be such that the granulates are fully converted into a pasty substance, but it is also conceivable that the granulates are partially melted. The reinforcement sheet 6 and the base layer 3 are attached to each other under pressure through adhering properties of the melted thermoplastic material. Subsequently, the base layer 3 including the reinforcement sheet 6 are transported along a cooling unit 10. It is advantageous that the reinforcement sheet 6 is directly supported by a rigid press element of the pressing unit 9, since a soft layer between the reinforcement sheet 6 and the rigid press element would increase the risk of deformation or damage of the reinforcement sheet 6 by granulates of the first layer 3 that are not fully melted. It provides the opportunity to apply relative large granulates in the base layer 3.

(6) In a next step a second layer or top layer 11 is provided on top of the reinforcement sheet 6. The top layer 11 is made from the same thermoplastic material as the base layer 3, but this may be different in an alternative embodiment. The thermoplastic material of the top layer 11 is melted and pressed into a sheet by nip rollers, and the still at least partially melted sheet 11 and the base layer 3 including the reinforcement sheet 6 are then pressed together by means of calandering rolls 12, resulting in a web having a smooth upper surface.

(7) At a position downstream of the calandering rolls 12 there may be arranged a cutting mechanism (not shown) to cut the resulting continuous web into separate panels which are then collected for further processing.

(8) In an alternative embodiment (not illustrated) the reinforcement sheet may be placed on top of a lower press plate or press member in a first step, after which thermoplastic granulates are spread over the reinforcement sheet to form the first layer. The granulates may be at least partially melted before or after spreading. Subsequently an upper press plate or press member is placed on top of the first layer and the lower and upper press plates or press members can press the first layer and the reinforcement sheet to each other. The resulting intermediate product may be turned upside down and the second layer of thermoplastic material, for example an at least partially melted sheet, can be applied on top of the reinforcement sheet at its side facing away from the first layer. In case of placing an at least partially melted sheet on top of the reinforcement sheet, this can be fixed thereto by means of calandering. It is also possible that the resulting intermediate product is not turned upside down and that second layer is applied onto the reinforcement sheet when the reinforcement sheet extends below the first layer.

(9) From the foregoing, it will be clear that the invention provides an improved method for manufacturing a panel including a reinforcement sheet.

(10) The invention is not limited to the embodiment shown in the drawing and described hereinbefore, which may be varied in different manners within the scope of the claims and their technical equivalents. For example, the first layer may be applied on the lower conveyor belt in melted condition instead of first spreading and then melting the granulates. Furthermore, heating of the granulates of the first layer may be performed before laying the reinforcement sheet and the first layer onto each other.