Manufacturing method for multi-layer floor panel

Abstract

In a first pressing stage making up the preliminary pressing, the glue layer forming the single multilayer flooring panel (1) is pressed for a time of between 5 seconds and 50 seconds until a physical local bonding of the layers is obtained, allowing the position of the solid wood sheet making up the top layer (4) to be seated on the core composite layer (2) covered with the adhesive. In a next stage, a stack is formed from a plurality of flooring panels (1) so pressed, after which the stack of preliminarily pressed flooring panels (1) is subjected to a second pressing stage constituting the main pressing for a time of more than 300 seconds until an adhesive bond of desired durability and strength is obtained, the adhesive (3) applied to the core composite layer (2) is a reactive hot melt polyurethane adhesive.

Description

[0001] The subject of the invention is a method for manufacturing a multilayer floor panel, wherein at least one layer is a composite panel made of a mineral raw material such as chalk and a polymer, in particular polyvinyl chloride (PVC), polystyrene, polypropylene or other polyolefins, the method being characterized in that at least one layer is made of a wooden veneer obtained by chipless processing. Technical Field

[0002] The low surface energy of panels made of composites with high PVC content, the sensitivity of such thermoplastic composites to temperature changes, and the non-uniform surface structure thereof revealed during the grinding process hinder the effective gluing of such composite layers with wooden veneer layers, in particular with wood layers obtained by chipless processing and drying. Wood layers obtained by chipless processing generally have non-uniform thickness, are not flat, do not exhibit uniform hardness, and are distinguished by variable hygroscopicity and anisotropic properties, which additionally hinder the gluing process. Additional difficulties arise in the manufacture of multilayer floor panels when the layers must be glued in a production line system. In this regard, difficulties arise in achieving an appropriate production volume. An additional problem is the selection of an adhesive system with the required reactivity and a sufficiently long open time, as well as a sufficiently short pressing time, while ensuring constant process conditions. Adhesives that ensure good bonding quality have an open time that is too short, resulting in difficulty in assembling a series of wooden layers quickly enough, and exceeding the open time results in the inability to achieve a durable adhesive bond. At the same time, the use of adhesives characterized by a long open time requires an increase in the pressing time, resulting in a lower efficiency of the manufacturing process or an increase in investment expenditure for additional gluing stations. Background Art

[0003] CN102051969A discloses a method for manufacturing a multilayer floor panel, in which a core plastic layer is glued to a solid wood layer using an epoxy resin-based adhesive in a cold or hot process. The process of gluing the wood layer to the plastic layer according to methods known in the art involves preparing the layers to be glued by cleaning the surfaces of the layers, applying the epoxy adhesive on the core layer to be glued, joining the plastic layer to the solid wood layer, pressing the layers to be joined, and cold pressing within 12 minutes to 30 minutes. In order to reduce the pressing time and at the same time increase the production capacity of the production line, the option of hot pressing at a temperature of 80°C to 100°C can be foreseen, which may however lead to a reduction in the bonding strength of the adhesive. In subsequent stages of the manufacturing process, the glued layered intermediate product is subjected to further processing, such as grooving, grinding and painting, to obtain the final product.

[0004] CN106183132A also discloses a method for manufacturing a multilayer floor panel having a top layer made of PVC joined to a previously prepared substrate in the form of a three-layer panel having a core layer made of softwood, such as poplar. The three-layer panel is glued using urea-formaldehyde resin and heated at a temperature of 95°C at a pressure of 10 kg / cm 2 Up to 12kg / cm 2 The top layer is glued to the substrate in the form of a three-layer panel using a polyurethane adhesive, but the substrate needs to be dried for 2 to 3 days at a temperature of 22°C to 26°C to make the process effective. In addition, considering the difficulty of gluing PVC layers to wood, the substrate is ground to an accuracy of ±0.1 mm and it is expected that the top layer will be pressed to the substrate for a period of 2 to 8 hours. Adhesives based on polyurethane-epoxy resin mixtures have also been successfully used to glue the top layer of floor panels made of PVC to a core based on magnesium chloride and magnesium oxide, stabilized with glass fiber cloth, as provided in DE102012000468B4.

[0005] A multilayer panel construction element manufactured by pressing a top layer into a support layer is also known from EP 3 235 973 B1. The top layer can also be manufactured separately, subsequently covered with a polyurethane material and glued to the support layer. This operation can be done by pressing at high pressure and temperature. In the known solution, the top layer is made of a mixture of wood material and adhesive, while the core layer is a polyurethane or acrylate-based material.

[0006] Known methods do not allow gluing floor panels comprising a core composite layer made mainly of mineral raw materials, such as chalk, with wooden veneers obtained using a chipless method using a bonding process implemented in a simple production line. Only when a number of parallel gluing stations are designed is it possible to perform the gluing operation of such panels in a production line method without negatively affecting the efficiency of the manufacturing process and the quality of the product obtained, which however requires increased investment costs. Summary of the invention

[0007] In the method according to the invention, a core composite layer made of at least 60% by weight of mineral raw materials and not more than 30% by weight of polymers and other auxiliary substances with a thickness of 4 to 7 mm is glued to a top layer made of solid wood sheets with a thickness ranging from 0.5 to 2.5 mm. According to the method:

[0008] - provide a core composite layer,

[0009] - Enable core composite layers,

[0010] - applying an adhesive layer to the core composite layer,

[0011] - providing a composite of solid wood sheets intended for the top layer, wherein each of the sheets is obtained by chip-free processing and drying, after which,

[0012] - applying a composite of previously prepared solid wood sheets constituting the top layer to the applied adhesive layer with an open time of less than 40 seconds, and

[0013] - The multilayer floor panels prepared in the described manner were subjected to a two stage pressing process.

[0014] The solution according to the invention is characterized in that:

[0015] - in a first pressing stage constituting a preliminary pressing, the glued layers forming the individual multilayer floor panels are pressed for a period of 5 to 50 seconds until physical local bonding of the binding layers is achieved, thus allowing the position of the solid wood sheets constituting the top layer to be set on the core composite layer, after which

[0016] - stacking a plurality of floor panels thus pressed, and then

[0017] - subjecting such a stack of preliminarily pressed floor panels to a second pressing stage as a main pressing for a period of more than 300 seconds until an adhesive bond of the desired elasticity and strength is obtained, wherein

[0018] - The adhesive applied to the core composite layer is a hot melt reactive polyurethane adhesive.

[0019] Preferably, in the first pressing stage, the layers constituting the individual multilayer floor panels are pressed for a time of 5 seconds to 20 seconds.

[0020] Preferably, in the first pressing stage, the layers constituting a single multilayer floor panel are pressed for a time of 8 seconds.

[0021] Preferably, PVC is used as the polymer in the core composite layer.

[0022] Preferably, chalk is used as the mineral raw material in the core composite layer.

[0023] Preferably, the absolute humidity of the solid wood sheets glued to the core composite layer is within 4% to 12%.

[0024] Preferably, activation of the core composite layer is achieved by grinding.

[0025] Preferably, activation of the core composite layer is achieved by corona treatment.

[0026] Preferably, the surface of the core composite layer is exposed to infrared radiation to heat it to a temperature between 20°C and 50°C prior to applying the adhesive layer.

[0027] Preferably, the amount of hot melt polyurethane adhesive applied to the core composite layer is 35 g / m 2 Up to 200g / m 2 within the range.

[0028] Preferably, the solid wood sheets forming the top layer are supplied with a thickness in the range of 0.9 mm to 1.2 mm.

[0029] Preferably, a stress relief layer is applied on the bottom portion of the core composite layer.

[0030] Preferably, the stress relief layer takes the form of a varnish layer.

[0031] Preferably, the second pressing stage is carried out in the cold state.

[0032] Beneficial Effects

[0033] The use of a two-stage pressing process for a core composite layer covered with a reactive polyurethane adhesive and covered with a veneer made of solid wood sheets allows maintaining an appropriate production capacity of the production line, thus leading to an increase in efficiency, wherein, in the first stage, the position of the layers to be joined is set and fixed.

[0034] The first pressing stage with expected local delamination bonds the solid wood sheets firmly enough to prevent them from changing position relative to the core composite layer when floor panels are moved and stacked. The production method and materials used allow for higher dimensional stability, adhesive bond moisture resistance and increased temperatures.

[0035] Using solid wood sheets having an absolute humidity in the range of 4% to 12% accelerates the onset of cohesion and results in the formation of covalent bonds, thereby producing an adhesive bond that exhibits the desired durability and strength.

[0036] Enabling the core composite layer by grinding allows for an increase in the contact surface area of ​​the bonded layer.

[0037] Enabling the core composite layer through corona treatment allows for an increase in surface tension.

[0038] Exposure of the core composite layer to infrared radiation increases the open time of the applied adhesive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the invention are presented in the accompanying drawings, in which:

[0040] Figure 1 A cross section of a section of a multilayer floor panel is shown.

[0041] Figure 2 A block diagram showing a method of producing a multi-layer floor panel;

[0042] Figure 3A block diagram of an alternative method of producing multi-layer floor panels is presented;

[0043] Figure 4 A block diagram showing another alternative method of producing a multi-layer floor panel;

[0044] Figure 5 shows a perspective view of a single solid wood sheet placed on a flat surface obtained using chipless machining;

[0045] Figure 6 shows a perspective view of a portion of a solid wood sheet glued to a core composite layer obtained using chipless processing after a first pressing stage;

[0046] Figure 7 Selected stages of the production method are presented schematically;

[0047] Figure 8 A top view of a ready-made multi-layer floor panel manufactured using the method according to the invention is shown. DETAILED DESCRIPTION

[0048] like Figure 1 As shown in FIG. 8 , the multi-layer floor panel 1 comprises a core composite layer 2 , an adhesive layer 3 , a top layer 4 and an optional bottom stress relief layer 5 .

[0049] Figure 2 The stages of a production method for a multilayer floor panel 1 are shown, the multilayer floor panel 1 comprising a density of 1990 kg / m 3 The core composite layer 2, the adhesive layer 3 and the top layer 4. The production method is implemented in a production plant at a temperature of 24°C and a relative humidity of 55%. The core composite layer 2 is made of 70% by weight of chalk, 25% by weight of PVC and 5% by weight of auxiliary substances and has a thickness of 6 mm. The auxiliary substances are in the form of 4.5% by weight of talc, 0.3% by weight of stearin and 0.2% by weight of PE wax. The adhesive 3 used is a reactive hot-melt polyurethane adhesive RAPIDEX NP.2075LT having a viscosity of 16,000 mPa·s at a temperature of 150°C. At the same time, the top layer 4 includes a solid oak sheet with a thickness of 1 mm obtained by chipless processing and drying.

[0050] According to this production method:

[0051] - In a first stage S1, a core composite layer 2 is provided,

[0052] - in a second stage S2, the core composite layer 2 is activated by grinding,

[0053] - In the third stage S3, 80g / m 2 An amount of adhesive layer 3 is applied to the core composite layer 2,

[0054] - in a fourth stage S4, providing material for forming the top layer 4 in the form of rectangular oak veneer sheets having a relative humidity of 10%,

[0055] - in a fifth stage S5, the composite of solid wood sheets prepared in the previous stage S4 is laid as a top layer 4 on the adhesive layer 3 applied in stage S3 with an open time of 15 to 40 seconds,

[0056] - In the sixth stage S6, the multilayer panel prepared in stage S5 is subjected to a pressure of 1 N / mm 2 The first pressing stage, i.e., initial pressing, is carried out for 15 seconds under a pressure of

[0057] - in a seventh stage S7, forming a stack of 75 panels that have undergone preliminary pressing in stage S6, and subsequently,

[0058] - In the eighth stage S8, at 1.5 N / mm 2 The second cold pressing stage, i.e. the main pressing, was performed at a pressure of 375 seconds.

[0059] exist Figure 3 In another embodiment of the schematically illustrated method for producing a multi-layer floor panel 1, a material having a thickness of 7 mm and a density of 1910 kg / m 3 The core composite layer 2 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 talc, 0.3% by weight of stearin and 0.2% by weight of PE wax. The adhesive 3 used is KLEIBERIT 711.9.06LT with a viscosity of 20,000 mPa·s at a temperature of 160° C., while the top layer 4 comprises solid oak sheets obtained by chipless processing and drying, each having a thickness of 0.8 mm. The production method is carried out in a production plant at a temperature of 25° C. and a relative humidity of 50%.

[0060] According to this production method:

[0061] - In a first stage S1, a core composite layer 2 is provided,

[0062] - in a second stage S2', the core composite layer 2 is activated by grinding and corona treatment, wherein firstly grinding is carried out and the ground surface is subsequently subjected to corona treatment to increase the surface tension,

[0063] - In the third stage S3', the surface of the core composite layer 2 is heated to 35°C by infrared radiation, and then 70 g / m 2 An amount of adhesive layer 3 is applied to the core composite layer 2,

[0064] - in a fourth stage S4, providing the material for forming the top layer 4 in the form of a composite of rectangular solid oak sheets having an absolute humidity of 12%,

[0065] - in a fifth stage S5, the composite of solid wood sheets prepared in the previous stage S4 is placed as a top layer 4 on the adhesive layer 3 applied in stage S3' during an open time of 25 to 30 seconds,

[0066] - In the sixth stage S6, the multilayer panel prepared in stage S5 is subjected to a pressure of 0.9 N / mm 2 The first pressing stage, i.e., initial pressing, is carried out for 12 seconds under a pressure of

[0067] - in a seventh stage S7, forming a stack of 100 panels subjected to preliminary pressing in stage S6, and subsequently,

[0068] - In the eighth stage S8, at 1.5 N / mm 2 The second cold pressing stage, i.e. the main pressing, was performed at a pressure of 480 seconds.

[0069] Figure 4 Another embodiment of a production method for a multi-layer floor panel 1 is shown, the multi-layer floor panel 1 comprising a density of 2030 kg / m 3 A core composite layer 2, an adhesive layer 3, a top layer 4, and a bottom stress relief layer 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 and has a thickness of 5 mm, the auxiliary substances including 4.5% by weight of talc, 0.3% by weight of stearin and 0.2% by weight of PE wax. The adhesive 3 used is a chemically activated hot melt KLEIBERIT 706.1.50LT with a viscosity of 20,000 mPa·s at a temperature of 160°C. At the same time, the top layer 4 includes an oak veneer with a thickness of 1.2 mm obtained by chipless processing and drying, and the bottom stress relief 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 plant at a temperature of 23°C and a relative humidity of 45%.

[0070] According to this production method:

[0071] - in a first stage S1 , a core composite layer 2 is provided, wherein a bottom stress relief layer 5 is applied,

[0072] - in a second stage S2″, the layer is subjected to a corona treatment to increase the surface tension,

[0073] - In the third stage S3', the surface of the core composite layer 2 is heated to 25°C by infrared radiation with a power of 24 kW, and then 100 g / m 2 An amount of adhesive layer 3 is applied to the core composite layer 2,

[0074] - in a fourth stage S4, providing the material for forming the top layer 4 in the form of a composite of rectangular solid oak sheets having an absolute humidity of 12%,

[0075] - in a fifth stage S5, the composite of solid wood sheets prepared in the previous stage S4 is placed as a top layer 4 on the adhesive layer 3 applied in stage S3' during an open time of 25 to 30 seconds,

[0076] - In the sixth stage S6, the multilayer panel prepared in stage S5 is subjected to a pressure of 1.2 N / mm 2 The first pressing stage, i.e., initial pressing, is carried out for 8 seconds under a pressure of

[0077] - in a seventh stage S7, forming a stack of 120 panels subjected to preliminary pressing in stage S6, and subsequently,

[0078] - In the eighth stage S8, at 1.7 N / mm 2 The second pressing stage, i.e. the main pressing, was performed at a pressure of 500 s for 520 s.

[0079] During the initial pressing, the pressure is adjusted to 0.9 N / mm for 5 to 50 seconds. 2 Up to 1.2N / mm 2 The pressure used in the range of 5 to 100° is used to obtain a physical partial joining of the layers to be joined. 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 upper limits specified is not necessary to ensure a clear positioning of the top layer 4 on the core composite layer 2.

[0080] The second pressing stage, which constitutes the main pressing, does not require any special conditions with regard to air humidity or ambient temperature. This pressing stage is carried out in the cold at the temperature of the production hall without the need for additional heating. Figure 2 , Figure 3 and Figure 4 In the embodiment presented in FIG. 1 , the required hardness and strength of the adhesive layer 3 are within 300 seconds to 600 seconds and within 1.5 N / mm 2 and 1.7N / mm 2 Longer main pressing times and higher pressures may also be used, but in the process according to the invention, increasing the time or pressure above the upper limits specified does not significantly increase the strength of the adhesive bond.

[0081] like Figure 5 As shown in , the individual solid wood sheets produced using chipless processing are not flat. The wavy surface of the sheet is mainly a result of the production and drying technology used.

[0082] In stage six S6, as in the embodiment of the manufacturing method for the multi-layer floor panel 1 Figures 2 to 4 As shown in the block diagram of , preliminary pressing is performed. The purpose of performing preliminary pressing in stage S6 is to finally position the top layer 4 on the core composite layer 2.

[0083] Figure 6 It is shown that the top layer 4 and the core composite layer 2 are partially joined using the adhesive layer 3 after the preliminary pressing stage. After this stage, delamination of the layers to be joined appears in the form of local delamination 6 at the locations of the corrugations of the surface of the sheet forming the top layer 4. However, the pressed adhesive layer 3 forms sufficient adhesion in the locations in contact with the layers to be joined to ensure a stable position of the top layer 4 relative to the core composite layer 2 and to maintain this stable position during the transportation of the preliminary pressed panel to the stacking stage.

[0084] exist Figure 7 A schematic diagram of selected stages of the production method for a multilayer floor panel is shown in FIG. In a third stage S3, a roller dispenser 7 is used to provide a uniform application of an adhesive layer 3 on the core composite layer 2. In a fourth stage S4, the materials required to form the top layer 4 are provided, while in the next stage S5, a composite of solid wood sheets is laid on the core composite layer 2 covered with the adhesive layer 3. In a sixth stage S6, the single multilayer floor panel prepared in the previous stage is subjected to a preliminary pressing process, after which, in a seventh stage S7, tens or hundreds of panels subjected to the preliminary pressing are stacked, and in an eighth stage S8, the stack thus prepared is subjected to main pressing.

[0085] Figure 8 A multi-layer floor panel 1 of dimensions 1165 mm x 2235 mm is shown, made using the method according to the invention, wherein a top layer 4 consists of 12 rectangular solid oak sheets, attached to a core composite layer using adhesive in a two stage pressing process.

[0086] The multilayer floor panel 1 manufactured using the method according to the invention is characterized by the waterproof properties of the adhesive layer confirmed by the ANSI HPVAEF2020 test and a peel strength of the top layer 4 measured perpendicular to the surface according to EN 311 of at least 1.5 N / mm 2 .

Claims

1. A method for producing a multi-layer floor panel (1), wherein: A core composite layer (2) made of at least 60% by weight of mineral raw materials and not more than 30% by weight of polymers and other auxiliary substances with a thickness of 4 mm to 7 mm is glued to a top layer (4) made of solid wood sheets with a thickness ranging from 0.5 mm to 2.5 mm, wherein Providing the core composite layer (2), activating the core composite layer (2), applying an adhesive layer (3) to the core composite layer (2), providing a composite of solid wood sheets intended for said top layer (4), in which each of the sheets is obtained using chipless processing and drying, Thereafter, during an open time of less than 40 seconds, the previously prepared composite of solid wood sheets is placed onto the applied adhesive layer, thereby constituting the top layer (4), and The multi-layer floor panels prepared in this way are subjected to two-stage pressing, Features: - in a first pressing stage constituting a preliminary pressing, pressing the glued layers forming the individual multilayer floor panels (1) for a time between 5 and 50 seconds, until a physical local bonding of the layers with local delamination (6) is obtained, allowing the position of the solid wood sheets constituting the top layer (4) to be determined on the core composite layer (2), and then - stacking of a plurality of floor panels (1) thus pressed, after said stacking - subjecting the stack of preliminarily pressed floor panels (1) to a second pressing stage constituting a main pressing for a period not exceeding 300 seconds, until an adhesive bond of the desired elasticity and strength is obtained, wherein A reactive hot melt polyurethane adhesive is used as the adhesive (3) applied to the core composite layer (2).

2. The method according to claim 1, characterized in that In the first pressing stage, the glue layers forming the individual multilayer floor panels (1) are pressed for 5 to 20 seconds.

3. The method according to claim 2, characterized in that In the first pressing stage, the glue layers forming the individual multilayer floor panels (1) are pressed for 8 seconds.

4. The method according to claims 1 to 3, characterized in that Polyvinyl chloride is used as the polymer in the core composite layer (2).

5. The method according to claims 1 to 4, characterized in that Chalk is used as a raw material in the core composite layer (2).

6. The method according to claims 1 to 5, characterized in that The absolute humidity of the solid wood sheets glued to the core composite layer (2) is in the range of 4% to 12%.

7. The method according to claims 1 to 6, characterized in that The activation of the core composite layer (2) is carried out by grinding.

8. The method according to claims 1 to 6, characterized in that The activation of the core composite layer (2) is carried out by means of corona treatment.

9. The method according to claims 1 to 8, characterized in that Prior to applying the adhesive layer (3), the core composite layer is exposed to infrared radiation.

10. The method according to claims 1 to 9, characterized in that The amount of polyurethane adhesive applied to the core composite layer (2) is 35 g / m 2 With 200g / m 2 between.

11. The method according to claims 1 to 10, characterized in that The solid wood sheet forming the top layer (4) is provided to have a thickness ranging from 0.9 mm to 1.2 mm.

12. The method according to claims 1 to 11, characterized in that A stress relief layer (5) is applied to a lower portion of the core composite layer (2).

13. The method according to claims 1 to 12, characterized in that The stress relief layer (5) is in the form of a varnish layer.

14. The method according to claims 1 to 13, characterized in that The second pressing stage is carried out in a cold state.

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