Process for producing a laminate for a floor covering

Abstract

A method for producing a laminate (1), preferably for a floor covering, wherein the laminate (1) has a decorative layer and a wear layer made of polyurethane, includes the following steps: applying a first liquid polyurethane material (12) on a release layer (11) to form the wear layer, inserting a decorative sheet (14) into the first polyurethane material (12), applying a second liquid polyurethane material (17) on the decorative sheet (14), which is impregnated with the first polyurethane material (12) and with the second polyurethane material (17), supplying heat energy for curing the first polyurethane material (12) and the second polyurethane material (17), and separating the release layer (11) from the wear layer, wherein the heat energy is supplied to the first polyurethane material (12) and the second polyurethane material (17) from below through the release layer.

Claims

1. A method for producing a laminate for a floor covering, the laminate having a decorative layer and a wear layer of polyurethane, comprising following steps: applying a first liquid polyurethane material to a release layer to form the wear layer, inserting a decorative sheet into the first polyurethane material, applying a second liquid polyurethane material to the decorative sheet, which is thereby impregnated with the first polyurethane material and the second polyurethane material, supplying heat energy for curing the first polyurethane material and the second polyurethane material from below through the release layer, separating the release layer from the wear layer.

2. The method of claim 1, wherein the step of supplying heat energy comprises resting the release layer on at least one hotplate, the temperature of which is lower than 100 C.

3. The method of claim 1, further comprising the step of placing a separate reinforcing sheet, which is impregnated with the second polyurethane material, on the decorative sheet.

4. The method of claim 3, wherein the reinforcing sheet is made of a glass mat.

5. The method of claim 3, wherein the decorative sheet, the reinforcing sheet and the release layer are each moved as a continuous sheet over at least one hotplate.

6. The method of claim 5, wherein the release layer is held by negative pressure on the at least one hotplate.

7. The method of claim 3, wherein the separate reinforcing sheet is impregnated with the first polyurethane material.

8. The method of claim 1, wherein the release layer has a surface structure to form an outer surface of the wear layer having a corresponding surface structure.

9. The method of claim 1, further comprising the step of, before the decorative sheet is inserted, scattering mineral particles in a dry form onto the first polyurethane material.

10. The method of claim 1, wherein the first polyurethane material is composed of aliphatic polyurethane components and the second polyurethane material of aromatic polyurethane components.

11. The method of claim 1, wherein the decorative sheet is a decorative paper based on pulp with a weight per unit area of 20 to 80 g/m.sup.2.

12. The method of claim 1, wherein: the decorative sheet is guided as a continuous sheet over a first heating roller, the release layer is guided as a continuous sheet over a second heating roller, or the decorative sheet is guided as a continuous sheet over a first heating roller and the release layer is guided as a continuous sheet over a second heating roller.

13. The method of claim 1, further comprising the step of applying a third polyurethane material on the second polyurethane material.

14. The method of claim 13, further comprising the step of placing a functional sheet the third polyurethane material.

15. The method of claim 1, further comprising the step of placing a functional sheet on the second polyurethane material.

16. The method of claim 15, wherein the functional sheet is a cork plate.

17. The method of claim 15, wherein the functional sheet is a cork plate.

18. The method of claim 1, further comprising the step of applying an adhesive layer with a release film on one of the surfaces of the laminate facing away from the wear layer.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention will be explained in greater detail by means of a single FIGURE. The FIGURE is intended to illustrate the inventive process for producing the laminate diagrammatically.

DETAILED DESCRIPTION

(2) The FIGURE diagrammatically shows several successively arranged hotplates 10 (10a to 10f), over which a release layer 11 is guided in the form of a continuous sheet of release paper to produce a laminate 1. In the representation of the FIGURE, the release layer is moved from left to right, which is also illustrated by a horizontal direction of movement X. To begin with, a first polyurethane material 12 is applied on the release layer 11 from above at the height of the hotplate 10a. The first polyurethane material is in liquid form as it is being applied on the release layer 11. After the first polyurethane material 12 is applied onto the release layer 11, the dry corundum particles 13 are scattered on. Thereafter, a decorative sheet 14 is inserted in or placed on the first polyurethane material 12 (the terms insert and placed on are understood to be synonymous here). Since the first polyurethane material 12 is still liquid when the decorative sheet 14 is inserted, the impregnation of the decorative sheet 14 thus begins. The decorative sheet likewise is an endless sheet. Preferably, It is made of a decorative paper pulp.

(3) The vertical height of a roller 15, with the aid of which the decorative sheet 14 is supplied to the already deposited layers, can be adjusted so that the decorative sheet 14 is pressed slightly into the first polyurethane material 12.

(4) A separate reinforcing sheet 16, which is formed here as a continuous glass mat, is then placed over the decorative sheet 14. After the reinforcing sheet 16 is put down or inserted, a second liquid polyurethane material 17, which differs from the first polyurethane material 12, is applied.

(5) The second liquid polyurethane material 17 is followed by a third liquid polyurethane material 20, which may be fortified for example, with fillers. Finally, to form a functional layer, a functional sheet 21, which is supplied by a roller 22, is placed on the third polyurethane material 20. The individual layers or the laminate are/is not compressed.

(6) The impregnation of the decorative sheet 14 and of the reinforcing sheet 16 takes place both from below (primarily through the first polyurethane material 12) and also from above (primarily through the second polyurethane material 17). The degree of mixing of the polyurethane materials 12, 17 depends, on the one hand, on the permeability of sheets 14 and 16, and on the other, on the viscosity of the materials 12 and 17. The viscosity of the materials 12 and 17 can be adjusted inventively by controlling the heat supplied. The temperature of the hotplates and the feed rate of the release layer 11 can be used as control parameters.

(7) Just as also the decorative sheet 14, the release layer 11 is supplied by a roller, which is labeled 18 here. Another roller, with which the reinforcing sheet 16 is deflected, is labeled 19. Further rollers, which are not shown here and by means of which the respective sheets are supplied or deflected, may be heated in order to reduce the residual moisture of the sheets. It should be noted that the FIGURE shows the production only diagrammatically, so that the position shown of the individual, possibly heated rollers 15, 18, 19 and 22 may differ significantly from the position of a real implementation of the method. This also applies analogously to the distances, dimensions, etc. shown in the FIGURE.

(8) After passing by the last hotplate 10f, the polyurethane materials are cured to such an extent, that the release layer 11 can be separated from the laminate 1 and rolled up once again for further use. The laminate 1 can also be rolled up and thus stored and transported as a rolled-up product.

(9) The heat energy, by means of which curing of the first polymeric material 12 and of the second polymeric material 17 is controlled and/or accelerated, is supplied to the process by the hotplates 10. A heat transfer medium in the form of hot water, the temperature of which ranges from 75 to 90 C., flows through the hotplates 10 and heats these accordingly. The hotplates 10 apply their heat through the release layer 11 to the first polyurethane material 12 and the second polyurethane material 17. The hot water is supplied hotplate-specific. This means, for example, that a different amount of heat is emitted by hotplate 10f than, for example, by hot plate 10a. For example, if the first polyurethane material 12 is still too liquid when the corundum particles 13 are scattered on it, the initial curing can be accelerated somewhat by increasing the input of heat by hotplate 10a. Conversely, the curing of the first polymer material must also not be too fast, if at least a certain degree of impregnation of the sheets 14, 16 through the first polyurethane material is to take place.

(10) Assuming that after they have passed through the hotplate 10e, the decorative sheet 14 and the reinforcing sheet 16 are impregnated to the desired extent, a larger amount of heat may be supplied by the hotplate 10f to bring the curing to a conclusion quickly.

LIST OF REFERENCE SYMBOLS

(11) 1 Laminate 10 Hotplate (10a to 10f) 11 Release layer 12 First polyurethane material 13 Corundum particle 14 Decorative sheet 15 Roller 16 Reinforcng sheet 17 Second polyurethane material 18 Roller 19 Roller 20 Third polyurethane material 21 Funktional sheet 22 Roller X Direction of movement