MANUFACTURING METHOD FOR MULTI-LAYER FLOOR PANELS

Abstract

In a first pressing stage, constituting preliminary pressing, glued layers forming a single multi-layer floor panel (1) are pressed for a time between 5 and 50 seconds, until a physical, local joining of the layers is obtained allowing determination of the position of the sheets of solid wood constituting a top layer (4) being placed on a core composite layer (2) covered with an adhesive. In the next stage, a stack is formed from numerous floor panels (1) thus pressed, after which the said stack of preliminarily pressed floor panels (1) is subjected to pressing, constituting main pressing, for a time longer than 300 seconds, until the adhesive bond of the required durability and strength is obtained, wherein the adhesive (3) applied to the core composite layer (2) is a hot-melt polyurethane adhesive.

Claims

1. A method of producing multi-layer floor panels (1), in which a core composite layer (2) with a thickness of 4 to 7 mm, made of mineral raw materials in an amount of at least 60% by weight and polymers in an amount of no more than 30% by weight, as well as other auxiliary substances, is glued with a top layer (4) made of solid wood sheets with a thickness ranging from 0.5 to 2.5 mm, wherein the core composite layer (2) is provided, the core composite layer (2) is activated, a layer of adhesive (3) is applied to the core composite layer (2), a composition of sheets of solid wood is provided, intended for the top layer (4), in which each of the sheets is obtained using chipless machining and drying, thereafter, onto the applied layer of adhesive, during an open time shorter than 40 s, the composition of sheets of solid wood prepared earlier is placed, constituting the top layer (4), and the multi-layer floor panel prepared in such a manner is subjected to two-stage pressing, characterised in that in the first pressing stage, constituting preliminary pressing, glued layers forming the single multi-layer floor panel (1) are pressed for a time between 5 and 50 seconds, until a physical, local joining of the layers is obtained, with localised delamination (6), allowing determination of the position of the sheets of solid wood constituting the top layer (4) being placed on the core composite layer (2), and then numerous floor panels (1) such pressed are stacked, after which the second stage of pressing of the said stack of preliminarily pressed floor panels (1) is conducted, constituting main pressing, for a period no longer than 300 seconds, until an adhesive bond of the required resilience and strength is obtained, wherein as the adhesive (3) applied to the core composite layer (2) a reactive hot-melt polyurethane adhesive is used.

2. The method of claim 1, characterised in that in the first stage of pressing, the glued layers forming the single multilayer floor panel (1) are pressed for 5 to 20 seconds.

3. The method of claim 2, characterised in that in the first stage of pressing, the glued layers forming the single multilayer floor panel (1) are pressed for 8 seconds.

4. The method of claim 1, characterised in that PVC is used as the polymer in the core composite layer (2).

5. The method of claim 1, characterised in that chalk is used as the raw material in the core composite layer (2).

6. The method of claim 1, characterised in that the absolute humidity of solid wood sheets glued to the core composite layer (2) is in the range of 4 to 12%.

7. The method of claim 1, characterised in that the activation of the core composite layer (2) is conducted by way of grinding.

8. The method of claim 1, characterised in that the activation of the core composite layer (2) is conducted by way of corona treatment.

9. The method of claim 1, characterised in that prior to the application of the layer of adhesive (3), the core composite layer is exposed to infrared radiation.

10. The method of claim 1, characterised in that the amount of polyurethane adhesive applied to the core composite layer (2) is between 35 and 200 g/m.sup.2.

11. The method of claim 1, characterised in that the solid wood sheets provided forming the top layer (4) have a thickness ranging from 0.9 to 1.2 mm.

12. The method of claim 1, characterised in that a stress-relief layer (5) is applied to the lower part of the core composite layer (2).

13. The method of claim 12, characterised in that the stressrelief layer (5) has the form of a varnish layer.

14. The method of claim 1, characterised in that the second pressing stage is conducted cold.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] The embodiments of the invention are presented in the drawings, wherein:

[0037] FIG. 1 shows a cross-section of a section of the multi-layer floor panel.

[0038] FIG. 2 shows a block diagram of the method of producing multi-layer floor panels;

[0039] FIG. 3 presents a block diagram of an alternative method of producing multi-layer floor panels;

[0040] FIG. 4 shows a block diagram of another alternative method of producing multi-layer floor panels;

[0041] FIG. 5 shows a perspective view of a single sheet of solid wood obtained using chipless machining, placed on a flat surface;

[0042] FIG. 6 shows a perspective view of a part of the sheet of solid wood obtained using chipless machining, glued to the core composite layer, after the first pressing stage;

[0043] FIG. 7 presents selected stages of the production method in a schematic view;

[0044] FIG. 8 shows a top view of a ready multi-layer floor panel manufactured using the method according to the invention.

DESCRIPTION OF EMBODIMENTS

[0045] As shown in FIG. 1 the multi-layer floor panel 1 comprises a core composite layer 2, a layer of adhesive 3, a top layer 4 and an optional bottom stress-relief layer 5.

[0046] FIG. 2 shows the stages of the production method for multi-layer floor panels 1, including the core composite layer 2 with a density of 1990 kg/m.sup.3, the layer of adhesive 3, and the top layer 4. The production method is implemented in a production hall, at a temperature of 24 C. and a relative humidity of 55%. The core composite layer 2 is made of 70% chalk by weight, 25% by weight of PVC, and 5% by weight of auxiliary substances, in the form of 4.5% by weight of talcum, 0.3% by weight of stearin, and 0.2% by weight of PE wax, and has a thickness of 6 mm. The used adhesive 3 is a reactive hot-melt polyurethane adhesive, RAPIDEX NP. 2075 LT, with a viscosity of 16,000 mPa-s at a temperature of 150 C. Meanwhile, the top layer 4 consists of sheets of solid oak wood with a thickness of 1 mm obtained through chipless machining and drying.

[0047] According to this production method: [0048] in the first stage SI, the core composite layer 2 is provided, [0049] in the second stage S2, the core composite layer 2 is activated by grinding, [0050] in the third stage S3, the layer of adhesive 3 in the amount of 80 g/m.sup.2 is applied to the core composite layer 2, [0051] in the fourth stage S4, the material for forming the top layer 4 is provided, in the form of rectangular oak veneers with a relative humidity of 10%, [0052] in the fifth stage S5, the composition of solid wood sheets prepared in the previous stage S4 is laid on the layer of adhesive 3 applied in stage S3, within an open time of 15 to 40 seconds, as the top layer 4, [0053] in the sixth stage S6, the multi-layer panel prepared in the stage S5 is subjected to the first pressing stage, being preliminary pressing, for 15 seconds, at a pressure of 1 N/mm.sup.2, [0054] in the seventh stage S7, a stack of 75 pieces of panels that had been subjected to preliminary pressing in the stage S6 is formed, and subsequently, [0055] in the eighth stage S8, the second stage of cold pressing, being main pressing, is performed for a time of 375 seconds, at a pressure of 1.5 N/mm.sup.2.

[0056] In another embodiment of the production method for multi-layer floor panels 1, illustrated schematically in FIG. 3, the core composite layer 2 with a thickness of 7 mm and a density of 1910 kg/m.sup.3 is made of 63% by weight of chalk, 16% by weight of PVC, and 21% by weight of auxiliary substances, including 20.5% by weight of talcum, 0.3% by weight of stearin, and 0.2% by weight of PE wax. The adhesive 3 used is KLEIBERIT 711.9.06 LT, with a viscosity of 20,000 mPa-s at a temperature of 160 C., while the top layer 4 consists of sheets of solid ash wood, each with a thickness of 0.8 mm, obtained through chipless machining and drying. The production method is implemented in a production hall, at a temperature of 25 C. and a relative humidity of 50%.

[0057] According to this production method: [0058] in the first stage S1, the core composite layer 2 is provided, [0059] in the second stage S2, the core composite layer 2 is activated through grinding and corona treatment, where the grinding is implemented first and the ground surface is subsequently subjected to corona treatment in order to increase the surface tension, [0060] in the third stage S3, the surface of the core composite layer 2 is heated with infrared radiation to a temperature of 35 C., and then the layer of adhesive 3 in the amount of 70 g/m.sup.2 is applied to the core composite layer 2, [0061] in the fourth stage S4, material to form the top layer 4 is provided in the form of a composition of rectangular sheets of solid ash wood with an absolute humidity of 12%, [0062] in the fifth stage S5, the composition of solid wood sheets, prepared in the previous stage S4, is placed on the layer of adhesive 3 applied in the stage S3, within an open time of 25 to 30 seconds, as the top layer 4, [0063] in the sixth stage S6, the multi-layer panel prepared in the stage S5 is subjected to the first pressing stage, being preliminary pressing, for 12 seconds, at a pressure of 0.9 N/mm.sup.2, [0064] in the seventh stage S7, a stack of 100 pieces of panels subjected to preliminary pressing in the stage S6 is formed, and subsequently, [0065] in the eighth stage S8, the second stage of pressing, being the main pressing, is performed for a time of 480 seconds, at a pressure of 1.5 N/mm.sup.2.

[0066] FIG. 4 shows another embodiment of the production method for multi-layer floor panels 1, comprising the core composite layer 2 with a density of 2030 kg/m.sup.3, the layer of adhesive 3, the top layer 4, and the bottom stress-relief layer 5 with a thickness of 0.2 mm. The core composite layer 2 is made of 72% by weight of chalk, 23% by weight of PVC, and 5% by weight of auxiliary substances, consisting of 4.5% by weight of talcum, 0.3% by weight of stearin, and 0.2% by weight of PE wax, and has a thickness of 5 mm. The adhesive 3 used is the chemically activated hot-melt KLEIBERIT 706.1.50 LT, with a viscosity of 20,000 mPa-s at a temperature of 160 C. Meanwhile the top layer 4 consists of oak veneer, with a thickness of 1.2 mm, obtained through chipless machining and drying, while the bottom stressrelief layer 5 is applied to the bottom part of the core composite layer 2 as a UV cured varnish. The production method is implemented in a production hall at a temperature of 23 C. and a relative humidity of 45%.

[0067] According to this production method: [0068] in the first stage S1, the core composite layer 2 is provided, with the bottom stress-relief layer 5 applied, [0069] in the second stage S2, the layer is subjected to corona treatment to increase surface tension, [0070] in the third stage S3, the surface of the core composite layer 2 is heated with infrared radiation at a power of 24 KW to a temperature of 25 C., and then a layer of adhesive 3 in the amount of 100 g/m.sup.2 is applied to the core composite layer 2, [0071] in the fourth stage S4, material to form the top layer 4 is provided in the form of a composition of rectangular sheets of solid oak wood with an absolute humidity of 12%, [0072] in the fifth stage S5, the composition of solid wood sheets, prepared in the previous stage S4, is placed on the layer of adhesive 3 applied at the stage S3, within an open time of 25 to 30 seconds, as the top layer 4, [0073] in the sixth stage S6, the multi-layer panel prepared in the stage S5 is subjected to the first pressing stage, being preliminary pressing, for 8 seconds, at a pressure of 1.2 N/mm.sup.2, [0074] in the seventh stage S7, a stack of 120 pieces of panels subjected to preliminary pressing in the stage S6 is formed, and subsequently, [0075] in the eighth stage S8, the second stage of pressing, being the main pressing, is performed for a time of 520 seconds, at a pressure of 1.7 N/mm.sup.2.

[0076] A physical, local joining of the layers to be joined during preliminary pressing is obtained within a time of 5 to 50 seconds, with a pressure used within a range of 0.9 to 1.2 N/mm.sup.2. It is also possible to use longer preliminary pressing times and higher pressures, but in the method according to the invention increasing the time or pressure above the indicated upper limits is not necessary to ensure clear positioning of the top layer 4 on the core composite layer 2.

[0077] The second stage of pressing, constituting the main pressing, does not require special conditions related to air humidity or ambient temperature. This pressing stage is conducted cold, at the temperature of the production hall without additional heating. The required hardness and strength of the layer of adhesive 3, in the embodiments presented in FIG. 2, FIG. 3, and FIG. 4, is obtained within 300 to 600 seconds, at an applied pressure of between 1.5 and 1.7 N/mm.sup.2. It is also possible to use longer main pressing times and higher pressures, but in the method according to the invention, increasing the time or pressure above the indicated upper limits does not significantly increase the strength of the adhesive bond.

[0078] As shown in FIG. 5, a single sheet of solid wood made using chipless machining is not flat. The wavy surface of the sheet is primarily a result of the production and drying technologies used.

[0079] In the stage six S6, as illustrated in the block diagrams from FIG. 2 to FIG. 4 of the embodiments of the production method for multi-layer floor panels 1, preliminary pressing is conducted. The objective of preliminary pressing conducted in the stage S6 is to definitively position the top layer 4 on the core composite layer 2. FIG. 6 shows the localised joining of the top layer 4 and the core composite layer 2 using the layer of adhesive 3 after the preliminary pressing stage. After this stage, delamination of the layers to be joined in the form of localised delamination 6 occurs at the locations of waviness of sheet surfaces forming the top layer 4. However, the layer of pressed adhesive 3, formed, in places of contact with the layers to be joined, sufficient adhesion forces to ensure a stable position of the top layer 4 in relation to the core composite layer 2 and to maintain this stabilised position during the transport of preliminarily pressed panels to the stacking stage.

[0080] A schematic view of the selected stages of the production method for multi-layer floor panels is shown in FIG. 7. In the third stage S3, a roller dispenser 7 is used to provide uniform application of the layer of adhesive 3 on the core composite layer 2. In the fourth stage S4, the material necessary to form the top layer 4 is provided, while in the next stage S5, the composition of sheets of solid wood is laid on the core composite layer 2 covered with the layer of adhesive 3. In the sixth stage S6, a single multi-layer floor panel prepared in the previous stage is subjected to the preliminary pressing process, after which, in the seventh stage S7, several dozen or several hundred panels subjected to preliminary pressing are stacked, and in the eighth stage S8, the such prepared stack is subjected to main pressing.

[0081] FIG. 8 shows a multi-layer floor panel 1 with dimensions of 11652235 mm, made using the method according to the invention, with the top layer 4 composed of 12 rectangular sheets of solid oak wood attached using an adhesive to the core composite layer in the two-stage pressing process.

[0082] Multi-layer floor panels 1, manufactured using the method according to the invention, are characterized by the waterproof nature of the adhesive layer, confirmed by ANSI HPVA EF 2020 tests, and a peel-off strength of the top layer 4 of at least 1.5 N/mm.sup.2 measured according to EN 311 in the direction perpendicular to the surface.