Method of producing a panel unit and panel

Abstract

The invention relates to a method of producing a panel unit (10), comprising: providing a core (1) having a first surface (11) and a second surface (12) opposite the first surface (11); applying a surface layer to the first surface (11) of the core (1), the surface layer comprising a wood veneer layer (4) and a first binder layer (2) for attaching the wood veneer layer (4) to the first surface (11) of the core (1); applying a balancing layer to the second surface (12) of the core (1), the balancing layer comprising an unimpregnated paper (5) and a second binder layer (3) for attaching the unimpregnated paper (5) to the second surface (12) of the core (1); applying pressure to the surface layer, the balancing layer and the core (1) to form the panel unit (10). The disclosure also relates to a panel (10).

Description

Technical Field

[0001] Embodiments of this disclosure relate to a method for producing a panel unit, a panel unit, and a panel. Background Technology

[0002] Architectural panels, such as floor panels, typically have a bottom layer called a balancing layer, sometimes also referred to as a reaction layer. The balancing layer is designed to balance the surface layer, thus maintaining the panel's essentially flatness both after pressing and during installation.

[0003] For laminates having a surface layer comprising at least one layer of resin-impregnated paper, such as DPL (Direct Pressure Laminate), a balancing layer is typically formed of resin-impregnated paper to balance the forces formed by the resin-impregnated paper of the surface layer.

[0004] For veneered architectural panels with a surface layer including a wood veneer layer, the balancing layer typically includes the wood veneer layer. However, having wood veneer panels on both sides increases the cost of the panel and consumes more wood veneer panel resources.

[0005] When the surface layer comprises a thermosetting resin such as an amino resin, the balancing layer is adapted to counteract or balance the forces generated by the curing of the thermosetting resin during pressing, cooling, and installation under various climatic conditions.

[0006] When the thermosetting resins in the surface layer and balancing layer cure during pressing, the layer on the front surface of the core (suitable for forming the surface layer during installation) and the layer disposed on the rear surface of the core (referred to as the balancing layer) undergo a first shrinkage. The balancing layer balances the tension generated by the surface layer, and when the panel leaves the press, the panel is substantially flat with a small convex rearward bend. This first shrinkage and balancing of the panel is referred to below as "pressing balance". A second temperature shrinkage that occurs when the panel cools from approximately 150-200°C to room temperature is also balanced by the balancing layer, and the panel is substantially flat. This second balance is referred to below as "cooling balance". The small convex rearward bend is preferred because it counteracts the upward bend of the edges that occurs under dry conditions where the relative humidity may drop to 20% or lower in winter.

[0007] One issue is that this essentially flat panel involves tension caused by the shrinkage of the surface and balancing layers during pressing and cooling to room temperature.

[0008] The surface layer and core expand when indoor humidity is high in summer and contract when indoor humidity is low in winter. The panels will shrink and expand, and the edges may develop a tile-like deformation. A balancing layer is used to counteract this tile-like deformation. In installed panels, the balancing layer acts as a barrier to the diffusion of moisture from the underlying structure and minimizes the influence of the surrounding climate. Therefore, the balancing layer is suitable for balancing the contraction and expansion caused by compression, cooling, and changing climatic conditions.

[0009] In laminate flooring, standard SS-EN 13329:2016+A1:2018 specifies that, viewed from the finished surface of the flooring, the wadding at the long edges should be ≤0.50% indentation and ≤1.00% protrusion, and at the short edges, the wadding should be ≤0.15% indentation and ≤0.20% protrusion. Similar ranges are ideal for wood veneer flooring. However, it may be desirable to control the wadding within more restrictive limits, especially for the short edges. For the short edges, virtually no wadding, i.e., close to 0, may be advantageous. Numbers above 0 indicate convex wadding on the upper surface, and numbers below 0 indicate concave wadding on the upper surface. Wadding at the long edges typically decreases when floor panels are installed and mechanically locked to adjacent floor panels, especially for long planks. However, wadding at the short edges usually remains after the floor panels are installed. After installation, short side edges with residual corrugation can affect the visual perception of the installed flooring, making it appear warped. It is desirable to limit this curvature of the installed flooring panels to less than 0.2% of the panel width. Zero indicates no corrugation (flat), numbers above zero indicate convex corrugation on the upper surface, and numbers below zero indicate concave corrugation on the upper surface of the flooring panel. Summary of the Invention

[0010] The purpose of at least one embodiment of this disclosure is to provide improvements over the above-described and known technologies.

[0011] According to a first aspect, a method for manufacturing panel units is provided. The method includes:

[0012] A core having a first surface and a second surface opposite to the first surface is provided;

[0013] A surface layer is applied to a first surface of the core, the surface layer including a wood veneer layer and a first adhesive layer for attaching the wood veneer layer to the first surface of the core;

[0014] A balancing layer is applied to the second surface of the core, the balancing layer comprising unimpregnated paper and a second bonding layer for attaching the unimpregnated paper to the second surface of the core; and

[0015] Pressure is applied to the surface layer, balancing layer, and core to form panel units.

[0016] The steps of applying pressure may include applying heat and pressure.

[0017] "Unimpregnated" is understood to mean that it contains no synthetic resin or is substantially free of synthetic resin before being applied to the core, for example, containing less than 10% by weight of synthetic resin, preferably less than 5% by weight, such as less than 2.5% by weight of synthetic resin. In one example, no synthetic resin is added to the paper before it is applied to the core.

[0018] After pressing, the panel unit can be divided into individual panels. Panels can be architectural panels, such as floor panels, wall panels, furniture panels, countertop panels, etc.

[0019] The balancing layer may consist of unimpregnated paper and a second binder layer.

[0020] Unimpregnated paper can form the bottom surface of the panel unit after pressing.

[0021] The fiber orientation of the unimpregnated paper can follow the grain direction of the wood veneer layer.

[0022] The fiber orientation of unimpregnated paper can be oriented substantially parallel to the grain direction of the wood veneer layer, for example, at an angle of 25° or less to the parallel direction.

[0023] Unimpregnated paper may contain α-cellulose, for example, 80% by weight of α-cellulose, for example, at least 90% by weight of α-cellulose, for example, at least 95% by weight of α-cellulose. Unimpregnated paper may be α-cellulose paper.

[0024] Unimpregnated paper may be substantially free of natural resins, for example, containing less than 10% by weight of natural resins, for example, less than 5% by weight of natural resins, for example, less than 1% by weight of natural resins.

[0025] Unimpregnated paper may contain bleached fibers. Unimpregnated paper may be made from bleached pulp. Unimpregnated paper may be derived from delignified pulp.

[0026] Unimpregnated paper can have a strength of 15-150 g / m². 2 For example, 15-50g / m 2 For example, 20-40g / m 2 The weight.

[0027] Unimpregnated paper may be or may include unimpregnated decorative paper. This decorative paper may be colored or include printed patterns. This decorative paper may contain at least 80% by weight of α-cellulose, for example, at least 90% by weight of α-cellulose, for example, at least 95% by weight of α-cellulose. The decorative paper may be of a type intended for use in forming a decorative layer in laminated flooring.

[0028] Unimpregnated paper may be or may include unimpregnated cover paper. This cover paper may not have any printed patterns and / or decorations. This cover paper may contain at least 90% by weight α-cellulose, for example, at least 95% by weight α-cellulose, or at least 99% by weight α-cellulose. The cover paper may be of a type intended for use in forming a protective abrasion-resistant layer in laminated flooring.

[0029] The cover paper may include abrasion-resistant particles, such as corundum.

[0030] The balancing layer may be free of kraft paper or other paper containing unbleached fibers and / or natural resins.

[0031] The balancing layer may not have a wood veneer layer.

[0032] The second binder layer can be applied in liquid form.

[0033] The second binder layer may be provided in the form of a second resin-impregnated paper disposed between the second surface of the core and the unimpregnated paper, or may be or include a second resin-impregnated paper disposed between the second surface of the core and the unimpregnated paper.

[0034] The fiber orientation of the second resin-impregnated paper forming the first binder layer can be aligned along the grain direction of the wood veneer layer.

[0035] The fiber orientation of the second resin-impregnated paper forming the first binder layer can be oriented substantially parallel to the grain direction of the wood veneer layer, for example, at an angle of 25° or less to the parallel direction.

[0036] The fiber orientation of the second resin-impregnated paper forming the second binder layer can be aligned with the grain direction of the wood veneer layer.

[0037] The fiber orientation of the second resin-impregnated paper forming the second binder layer can be oriented substantially parallel to the grain direction of the wood veneer layer, for example, at an angle of 25° or less to the parallel direction.

[0038] The first binder layer can be applied in liquid form.

[0039] The first binder layer may be provided in the form of a first resin-impregnated paper disposed between the first surface of the wood veneer layer and the core, or may be or include a first resin-impregnated paper disposed between the first surface of the wood veneer layer and the core.

[0040] Applying pressure may include pressing the surface layer at a first temperature and pressing the balance layer at a second temperature, wherein the second temperature is lower than the first temperature.

[0041] The core can be a wood substrate.

[0042] The method may also include dividing the panel unit into individual panels after pressing.

[0043] The method may also include dividing the panel unit into individual panels after pressing, wherein each panel conforms to the requirements for tile-like deformation specified in SS-EN 13329:2016+A1:2018.

[0044] The upper surface of the panel may have a tile-like deformation of -0.15% to 0.2% at the short side edge of the panel.

[0045] The upper surface of the panel may have a tile-like deformation ranging from -0.5% to 1% at the long side edge of the panel.

[0046] From the top surface, values ​​greater than 0 indicate convex tile-like deformation, while values ​​less than 0 indicate concave tile-like deformation.

[0047] The method may also include dividing the panel unit into individual panels after pressing, wherein the tile-like deformation of the short side edge of the panel is less than 0.2% of the width of the short side edge, for example in the range of -0.15% to 0.2%.

[0048] According to a second aspect, a panel is provided. The panel includes: a core having a first surface and a second surface opposite to the first surface; a surface layer disposed on the first surface of the core, the surface layer including a wood veneer layer attached to the core by a first adhesive layer; and a balancing layer disposed on the second surface of the core, the balancing layer including unimpregnated paper attached to the core by the second adhesive layer.

[0049] Paneling can be architectural paneling, such as floor paneling, wall paneling, furniture components, building components, countertops, etc.

[0050] The balancing layer may consist of unimpregnated paper and a second binder layer.

[0051] Unimpregnated paper can form the bottom surface of the panel unit after pressing.

[0052] The fiber orientation of the unimpregnated paper can follow the grain direction of the wood veneer layer.

[0053] The fiber orientation of unimpregnated paper can be oriented substantially parallel to the grain direction of the wood veneer layer, for example, at an angle of 25° or less to the parallel direction.

[0054] Unimpregnated paper may contain α-cellulose, for example, 80% by weight of α-cellulose, for example, at least 90% by weight of α-cellulose, for example, at least 95% by weight of α-cellulose. Unimpregnated paper may be α-cellulose paper.

[0055] Unimpregnated paper may be substantially free of natural resins, for example, containing less than 10% by weight of natural resins, for example, less than 5% by weight of natural resins, for example, less than 1% by weight of natural resins.

[0056] Unimpregnated paper may contain bleached fibers. Unimpregnated paper may be made from bleached pulp. Unimpregnated paper may be derived from delignified pulp.

[0057] Unimpregnated paper can have a strength of 15-150 g / m². 2 For example, 15-50g / m 2 For example, 20-40g / m 2 The weight.

[0058] Unimpregnated paper may be or may include unimpregnated decorative paper. This decorative paper may be colored or include printed patterns. This decorative paper may contain at least 80% by weight of α-cellulose, for example, at least 90% by weight of α-cellulose, for example, at least 95% by weight of α-cellulose. The decorative paper may be of a type intended for use in forming a decorative layer in laminated flooring.

[0059] Unimpregnated paper may be or may include unimpregnated cover paper. This cover paper may not have any printed patterns and / or decorations. This cover paper may contain at least 90% by weight α-cellulose, for example, at least 95% by weight α-cellulose, or at least 99% by weight α-cellulose. The cover paper may be of a type intended for use in forming a protective abrasion-resistant layer in laminated flooring.

[0060] The cover paper may include abrasion-resistant particles, such as corundum.

[0061] The balancing layer may be free of kraft paper or other paper containing unbleached fibers and / or natural resins.

[0062] The balancing layer may not have a wood veneer layer.

[0063] The paneling may comply with the requirements for paneling tile deformation in SS-EN 13329:2016+A1:2018.

[0064] The upper surface of the panel may have a tile-like deformation of -0.15% to 0.2% at the short side edge of the panel.

[0065] The upper surface of the panel may have a tile-like deformation ranging from -0.5% to 1% along the long side of the panel.

[0066] The degree of tile-like deformation of the short side edge of the panel can be less than 0.2% of the panel width, for example, in the range of -0.15% to 0.2%.

[0067] From the top surface, values ​​greater than 0 indicate convex tile-like deformation, while values ​​less than 0 indicate concave tile-like deformation.

[0068] Unimpregnated should be understood as containing no synthetic resin or substantially no synthetic resin prior to pressing, for example, containing less than 10% by weight of synthetic resin, preferably less than 5% by weight, such as less than 2.5% by weight of synthetic resin. In one example, no synthetic resin is added to the paper prior to pressing.

[0069] Unimpregnated paper may be unimpregnated at the time of application, but may have absorbed some resin during pressing. The term "unimpregnated" refers to the original properties of the paper before it is formed as part of a panel unit.

[0070] The core can be a wood substrate.

[0071] According to a third aspect, a method for manufacturing panel units is provided. The method includes:

[0072] A core having a first surface and a second surface opposite to the first surface is provided;

[0073] A surface layer is applied to a first surface of the core, the surface layer including a wood veneer layer and a first adhesive layer for attaching the wood veneer layer to the first surface of the core;

[0074] A balancing layer is applied to the second surface of the core;

[0075] Pressure is applied to the surface layer, balancing layer, and core to form panel units;

[0076] The pressure application includes pressing a surface layer at a first temperature and pressing a balance layer at a second temperature, wherein the second temperature is lower than the first temperature.

[0077] The steps of applying pressure may include applying heat and pressure.

[0078] The balancing layer may include a second binder layer.

[0079] After pressing, the panel unit can be divided into individual panels. Panels can be architectural panels, such as floor panels, wall panels, furniture panels, countertop panels, etc.

[0080] The temperature difference between the first temperature and the second temperature can be at least 10°C.

[0081] The temperature difference can be less than 20℃.

[0082] The temperature difference can be in the range of 10-20℃.

[0083] Both the first and second temperatures can exceed the ambient temperature.

[0084] Both the first and second temperatures can exceed 120°C.

[0085] The first binder layer may be provided in the form of a first resin-impregnated paper disposed between the first surface of the wood veneer layer and the core, or may be or include a first resin-impregnated paper disposed between the first surface of the wood veneer layer and the core.

[0086] The balancing layer may include unimpregnated paper and a second binder layer.

[0087] The second binder layer can be arranged between the core and the unimpregnated paper.

[0088] Unimpregnated paper may contain α-cellulose.

[0089] The balancing layer may be provided in the form of a second resin-impregnated paper disposed on the second surface of the core, or may be or include a second resin-impregnated paper disposed on the second surface of the core.

[0090] The first binder layer can be applied in liquid form.

[0091] The second binder layer can be applied in liquid form.

[0092] The method may also include dividing the panel unit into individual panels after pressing.

[0093] The method may also include dividing the panel unit into individual panels after pressing, wherein each panel conforms to the requirements for tile-like deformation specified in SS-EN 13329:2016+A1:2018.

[0094] The upper surface of the panel may have a tile-like deformation of -0.15% to 0.2% at the short side edge of the panel.

[0095] The upper surface of the panel may have a tile-like deformation ranging from -0.5% to 1% at the long side edge of the panel.

[0096] The method may also include dividing the panel unit into individual panels after pressing, wherein the tile-like deformation of the short side edge of the panel is less than 0.2% of the width of the short side edge of the panel, for example in the range of -0.15% to 0.2%.

[0097] The balancing layer may not have a wood veneer layer.

[0098] The core can be a wood substrate. Attached Figure Description

[0099] The present disclosure will be described in more detail by way of embodiments, with reference to the accompanying drawings which illustrate embodiments thereof.

[0100] Figure 1 An embodiment of the process for producing panel units is shown.

[0101] Figure 2 It shows that according to Figure 1 The process shown produces a panel unit or part of a panel.

[0102] Figure 3 An embodiment of the process for producing panel units is shown.

[0103] Figure 4 It shows that according to Figure 3 The process shown produces a panel unit or part of a panel. Detailed Implementation

[0104] Figure 1 An example of the process for producing panel unit 10 is shown. Panel unit 10 may be designed to form a single panel or may be designed to be divided into multiple individual panels. The panel may be an architectural panel, such as a floor panel, wall panel, furniture component, building component, work surface, etc. The architectural panel may be provided with a mechanical locking system designed to connect one architectural panel to another.

[0105] exist Figure 1 In this process, a core 1 is provided. Core 1 can be a wood-based substrate, such as MDF or HDF board. Core 1 can be plywood. Core 1 can be a thin-sheet core. Core 1 can be particleboard. Core 1 can be thermoplastic board. Core 1 is preferably produced prior to this method. Core 1 can be wood fiber based. Core 1 may include binders and fillers, such as organic and / or inorganic binders.

[0106] In one example, core 1 is a single-layer core, not a multi-layer core, such as plywood. In one example, core 1 differs from the wood veneer layer 4, for example, in material or construction. In one example, the thickness of core 1 is at least twice the thickness of the wood veneer layer 4, for example, 2-20 times, or 3-10 times. Core 1 may not have a veneer layer.

[0107] The core 1 may have a thickness of 3-12 mm, for example 3-10 mm, or for example 5-10 mm. The core 1 may be rigid, for example inflexible, or a sheet at least 1 m long that is inflexible under its own weight at ambient temperature (20°C).

[0108] Figure 1 An example is shown where the process is a so-called continuous process. Certain layers may be provided in the form of webs and fed into the press.

[0109] A first binder layer 2 is disposed on the first surface 11 of the core 1. Figure 1 In the example shown, the first binder layer 2 is formed of a first resin-impregnated paper 2a. The resin-impregnated paper 2a is applied to the first surface 11 of the core 1.

[0110] The resin can be a thermosetting binder, such as an amino resin, melamine-formaldehyde resin, or urea-formaldehyde resin. The resin can be urea-formaldehyde resin, phenolic resin, melamine-formaldehyde resin, polyurethane, polyester, emulsion polymer isocyanate (EPI), or a combination thereof. Alternatively, the resin can be a thermoplastic binder. Thermoplastic binders can be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyvinyl alcohol (PVOH), polyvinyl butyral (PVB), and / or polyvinyl acetate (PVAc), or a combination thereof. The resin may include a hot melt or pressure-sensitive adhesive. The resin can be an acrylic resin or a methacrylic resin.

[0111] In alternative examples, the first binder layer 2 can be provided and applied in different forms. For example, the first binder layer 2 can be applied as a first binder in liquid form to the first surface 11 of the core 1. Alternatively, the first binder layer 2 can be applied as a first binder in powder form to the first surface 11 of the core 1. Referring to the binder of the resin-impregnated paper 2a, the first binder can be one of the two examples of the types disclosed above.

[0112] The amount of binder applied can be 75-150 g / m². 2 Within a certain range. In one example, the amount of binder applied can be 50-300 g / m². 2 Within the range.

[0113] like Figure 1 As shown, the wood veneer layer 4 is applied onto the first adhesive layer 2. The first wood veneer layer 4 may be a flat-cut veneer, a rotary-cut veneer, a sawn veneer, and / or a semi-circular cut veneer.

[0114] Wood veneer layer 4 can be selected from oak, maple, birch, walnut, ash, and pine. Wood veneer layer 4 can have a thickness of less than 1 mm, for example, from 0.2 mm to 0.8 mm.

[0115] The thickness of the core layer 1 can exceed the thickness of the wood veneer layer 4. For example, the core layer 1 can have a thickness of 1-12 mm, such as 3-10 mm.

[0116] The fiber direction of the first resin-impregnated paper 2a can be substantially parallel to the grain direction of the wood veneer layer 4. "Substantially parallel" means within 25° of the parallel direction, for example, within 15° of the parallel direction.

[0117] The fiber orientation of paper is formed during the papermaking process, in which the fibers align themselves along the direction of the wire mesh during paper formation. Fiber orientation refers to the average fiber orientation, along which at least 70%, for example, at least 80%, of the fibers are oriented.

[0118] As the tree grows, a grain direction is formed. The slender, longitudinal cells align with the axis of the trunk, branches, or roots, thus creating the grain direction. The grain direction refers to the average grain direction, in which at least 70%, for example, at least 80%, of the wood fibers in the wood veneer layer 4 points towards this average grain direction.

[0119] When the wood veneer layer 4 has been applied, the first adhesive layer 2 is disposed between the first surface 11 of the core 1 and the wood veneer layer 4.

[0120] The first binder layer 2 and the wood veneer layer 4 are intended to be pressed together to form the surface layer 20.

[0121] A second binder layer 3 is applied to the second surface 12 of the core 1. The second surface 12 of the core 1 is opposite to the first surface 11 of the core 1. Figure 1 In the example shown, the second binder layer 3 is formed of a second resin-impregnated paper 3a. The second resin-impregnated paper 3a is applied to the second surface 12 of the core 1. The fiber direction of the second impregnated paper 3a may be oriented along the grain direction of the wood veneer layer 4. The fiber direction of the second impregnated paper 3a may be oriented substantially parallel to the grain direction of the wood veneer layer 4. "Substantially parallel" means within 25° of the parallel direction, for example, within 15° of the parallel direction.

[0122] The resin can be a thermosetting binder, such as an amino resin, melamine-formaldehyde resin, or urea-formaldehyde resin. The resin can be urea-formaldehyde resin, phenolic resin, melamine-formaldehyde resin, polyurethane, polyester, emulsion polymer isocyanate (EPI), or a combination thereof. Alternatively, the resin can be a thermoplastic binder. Thermoplastic binders can be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyvinyl alcohol (PVOH), polyvinyl butyral (PVB), and / or polyvinyl acetate (PVAc), or a combination thereof. The resin may include a hot melt or pressure-sensitive adhesive. The resin can be an acrylic resin or a methacrylic resin.

[0123] In alternative examples, the second binder layer 3 can be provided and applied in different forms. For example, the second binder layer 3 can be applied as a second binder in liquid form to the second surface 12 of the core 1. As a further alternative, the second binder layer 3 can be applied as a second binder in powder form to the second surface 12 of the core 1. Referring to the binder of the second resin-impregnated paper 3a, the second binder can be one of the two examples of the types disclosed above.

[0124] The amount of binder applied can be 75-150 g / m². 2 Within a certain range. In one example, the amount of binder applied can be 50-300 g / m². 2 Within the range.

[0125] Unimpregnated paper 5 is applied to the second binder layer 3. Unimpregnated paper 5 may contain at least 80% by weight of α-cellulose, such as at least 90% by weight of α-cellulose, such as at least 95% by weight of α-cellulose.

[0126] Unimpregnated paper 5 can be an unimpregnated cover paper. In another example, unimpregnated paper 5 can be the type of decorative paper used in the production of laminated products, although it is not impregnated.

[0127] Unimpregnated cover paper may contain at least 90% by weight of α-cellulose, such as at least 95% by weight of α-cellulose, such as at least 99% by weight of α-cellulose.

[0128] Unimpregnated paper 5 can have 15-150 g / m 2 For example, 15-50g / m 2 The weight. In one example, unimpregnated paper 5 may have 18-50 g / m². 2 For example, 20-40g / m 2 The weight. In another example, unimpregnated paper 5 can have 15-50 g / m². 2 The weight.

[0129] Unimpregnated should be understood as containing no synthetic resin, or substantially no synthetic resin, for example, containing less than 10% by weight of synthetic resin, preferably less than 5% by weight, such as less than 2.5% by weight of synthetic resin. In one example, no synthetic resin is added to the paper before it is applied to the core.

[0130] In addition, unimpregnated paper may be substantially free of natural resins, for example, containing less than 10% by weight of natural resins, for example, less than 5% by weight of resins, for example, less than 1% by weight of natural resins.

[0131] Unimpregnated paper may contain bleached fibers. Unimpregnated paper may be made from bleached pulp. Unimpregnated paper may be derived from delignified pulp.

[0132] The fiber orientation of the unimpregnated paper 3a can be substantially parallel to the grain direction of the wood veneer layer 4. "Substantially parallel" means within 20° of the parallel direction, for example, within 10° of the parallel direction.

[0133] The second binder layer 3 and the unimpregnated paper 5 are intended to form a balancing layer 30 after pressing. The balancing layer 30 is intended to balance the forces formed by the surface layer 20, which includes the wood veneer layer 4 and the first binder layer 2, during the pressing process, after pressing, and during installation.

[0134] The wood veneer layer 4, the first adhesive layer 2, the core 1, the second adhesive layer 3, and the unimpregnated paper 5 are pressed together in a press 40 to form the panel unit 10. The press can be stationary, or as... Figure 1 The example shown is a continuous press 40.

[0135] The applied pressure can be in the range of 30-60 bar. The pressurization time can be 10-60 seconds. The applied temperature can be in the range of 120-250°C, for example, in the range of 150-200°C, such as in the range of 180-200°C.

[0136] In one example, a temperature difference exists between a first pressing surface 41, intended to apply pressure to the surface layer 20, and a second pressing surface 42, intended to apply pressure to the balancing layer 30. The temperature of the first pressing surface 41 may be higher than that of the second pressing surface 42. The wood veneer layer 4 of the surface layer 20 thermally insulates the first adhesive layer 2, resulting in a lower temperature at the first adhesive layer 2 than at the wood veneer layer 4. To compensate for the insulating effect of the wood veneer layer 4, the applied temperature can be increased. However, from the perspective of balancing the final product, the correspondingly increased temperature at the balancing layer 30 has proven to be disadvantageous.

[0137] The temperature difference between the first pressing surface 41, intended for pressing the surface layer 20 including the wood veneer layer 4, and the second pressing surface 42, intended for pressing the balancing layer 30, can be at least 10°C. The temperature difference can be less than 20°C. The temperature difference can be in the range of 10-20°C.

[0138] Both surface layer 20 and balancing layer 30 can be pressed at temperatures exceeding ambient temperature, such as above 120°C, for example, 120-250°C. Cold pressing is not intended, and layers 20 and 30 are both hot-pressed.

[0139] The temperature difference between the first pressing surface 41, which is intended to press the surface layer 20 including the wood veneer layer 4, and the second pressing surface 42, which is intended to press the surface of the balance layer 30, can be used to control the shape of the panel 100 formed by the panel unit 10 after pressing. By increasing the temperature difference, a more concave shape of the panel 100 can be obtained.

[0140] After pressing, panel unit 10 is obtained. Panel unit 10 can be divided into multiple individual panels 100, such as architectural panels. The width and length of such panels 100 are smaller than the width and / or length of panel unit 10. For example, depending on the original dimensions of panel unit 10 and the desired dimensions of architectural panels 100, panel unit 10 can be divided into 2-10 panels 100, for example, each panel unit 10 can be divided into 4-6 panels 100. Panel 100 can have a rectangular shape, with two opposing long side edges and two opposing short side edges. Panel 100 can be architectural panels, such as floor panels, wall panels, furniture components, architectural components, worktops, etc. Panel 100 can be provided with a mechanical locking system designed to connect panels to adjacent panels.

[0141] After pressing, the panel 100 obtained from panel unit 10 shall at least meet the requirements for wavy deformation regarding the long side edges as specified in standard SS-EN 13329:2016+A1:2018. After pressing, the panel 100 obtained from panel unit 10 shall at least meet the requirements for wavy deformation regarding the short side edges as specified in standard SS-EN 13329:2016+A1:2018. Although laminate flooring is specified, the requirements specified in this standard also apply to panels with finished surfaces. Regarding wavy deformation, standard SS-EN 13329:2016+A1:2018 specifies that for laminate flooring, the wavy deformation of the upper surface of the panel, such as the decorative surface of the panel (optionally including a transparent abrasion layer), shall have a concavity of ≤0.5% and a protrusion of ≤1% at the long side edges. Tiling deformation is measured as the maximum deviation of the decorative surface from a straight line at its edge divided by the length of the edge. Viewed from the top surface, values ​​greater than 0 indicate convex tiling deformation, while values ​​less than 0 indicate concave tiling deformation. In one example, the top surface 11 of panel 100 meets the requirements of ≤0.50% indentation and ≤1.00% protrusion at its long edge. In another example, the top surface 11 of panel 100 meets the requirements of ≤0.50% indentation and ≤1.00% protrusion at its short edge. In yet another example, the top surface 11 of panel 100 meets the requirements of ≤0.15% indentation and ≤0.20% protrusion at its short edge. In yet another example, the top surface 11 of panel 100 exhibits essentially no tiling deformation at its short edge, i.e., close to 0 and substantially flat, for example, ≤0.15% indentation and ≤0.2% protrusion. In one example, the upper surface 11 of panel 100 has essentially no tile-like deformation at the short side edge, i.e., close to 0, with a recess of, for example, <0.15% and a protrusion of ≤0.2%, and the upper surface 11 of panel 100 has a recess of ≤0.5% and a protrusion of ≤1% at the long side edge.

[0142] In this disclosure, the wood veneer layer traditionally used as a balancing layer has been replaced by unimpregnated paper. It has been shown that the properties of unimpregnated paper are equivalent to those of wood veneer panels in controlling corrugation. For example, the fiber orientation of the unimpregnated paper can be used to mimic the grain orientation of the wood veneer layer. By excluding wood veneer panels from the balancing layer, less wood is consumed because the balancing layer without wood veneer panels achieves proper balance. The use of wood veneer panels is limited to surfaces that are intended to be visible when panel 100 is installed, for example, as floor paneling or the like.

[0143] Furthermore, it has been shown that replacing the wood veneer balancing layer with unimpregnated paper results in favorable waviness control of panel 100. Short-side waviness after pressing is close to zero. Compared to the wood veneer balancing layer, unimpregnated paper provides improved control over waviness control of panel 100.

[0144] Figure 2 The pressed panel unit 10 or panel 100 is shown. Panel 100 can be an architectural panel, such as a floor panel, wall panel, furniture component, building component, work surface, etc.

[0145] Figure 2 Including the cross-section, and the cross-sectional view of the pressed panel unit 10 corresponds to the cross-sectional view of the panel 100 obtained by dividing the panel unit 10 after pressing. Therefore, Figure 2 Both panel unit 10 and panel 100 can be referred to. For simplicity, in the following text, only panel unit 10 will be referred to.

[0146] The panel unit 10 includes a surface layer 20 disposed on a first surface 11 of the core 1 and a balancing layer 30 disposed on a second surface 12 of the core 1. The core 1 is as shown above. Figure 1 The type of description.

[0147] Surface layer 20 includes a wood veneer layer 4 and a first adhesive layer 2. The wood veneer layer 4 is as shown above. Figure 1 The type described. The first binder layer 2 is the reference above. Figure 1 The type described. As described above, the first binder layer 2 may include a first resin-impregnated paper 2a. The first binder layer 2 is disposed between the first surface 11 of the core 1 and the wood veneer layer 4. An additional layer may be applied to the upper surface of the wood veneer layer 4. The wood veneer layer 4 may be provided with a coating, such as one or more layers of paint, or a protective layer, such as a cover layer.

[0148] The balancing layer 30 includes a second binder layer 3 and unimpregnated paper 5. The second binder layer 4 is disposed between the second surface 12 of the core 1 and the unimpregnated paper 5. The balancing layer 30 has no wood veneer panel. The type and arrangement of the unimpregnated paper 5 are as described above. Figure 1 The second binder layer 5 is as described above. Figure 1 The type described. As an example, the second binder layer 3 may include a second resin-impregnated paper 3a.

[0149] During the pressing process, the unimpregnated paper 5 may absorb at least some of the binder 3a from the second binder layer 3. Therefore, in some cases, the unimpregnated paper 5 may contain some resin after pressing. However, the term "unimpregnated" is intended to refer to the original composition of the paper, i.e., the composition of the paper as defined above before application.

[0150] As described above, the unimpregnated paper 5 accordingly serves as the wood veneer panel arranged in the balancing layer 30. The corrugation of the panel 100 is controlled to be less than the desired value. As an example, the panel 100 can meet the requirements for corrugation specified for the long side edge in SS-EN 13329:2016+A1:2018. As an example, the panel 100 can meet the requirements for corrugation specified for the short side edge in SS-EN 13329:2016+A1:2018. For the short side edge of the panel 100, the requirements for corrugation of the long side edge of the panel in SS-EN 13329:2016+A1:2018 can also be met. For the long side edge of the panel 100, the requirements for corrugation of the short side edge of the panel in SS-EN 13329:2016+A1:2018 can also be met.

[0151] Figure 3 An example of the process for producing panel unit 10' is shown. Panel unit 10' can be in the form of a single panel, or it can be intended to be divided into several individual panels. The panel can be an architectural panel, such as a floor panel, wall panel, furniture component, building component, work surface, etc. The architectural panel may be provided with a mechanical locking system designed for connecting one architectural panel to another.

[0152] exist Figure 3 In this process, a core 1 is provided. Core 1 can be a wood substrate, such as MDF or HDF board. Core 1 can be plywood. Core 1 can be a thin-sheet core. Core 1 can be particleboard. Core 1 can be thermoplastic board. Core 1 is preferably produced prior to this method.

[0153] A second binder layer 3 is applied to the second surface 12 of the core 1, such as Figure 3 As shown in step A.

[0154] exist Figure 3 In the example shown, the second binder layer 3 is in the form of a second binder 3a applied in liquid form. The second binder 3a can be applied by a roller 50 or any other suitable application device.

[0155] The second binder 3a of the second binder layer 3 may be a thermosetting binder, such as an amino resin, such as melamine-formaldehyde resin or urea-formaldehyde resin. The second binder 3a may be urea-formaldehyde, phenolic, melamine-formaldehyde, polyurethane, polyester, emulsion polymer isocyanate (EPI), or a combination thereof. Alternatively, the second binder 3a may be a thermoplastic binder. Thermoplastic binders may be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyvinyl alcohol (PVOH), polyvinyl butyral (PVB), and / or polyvinyl acetate (PVAc), or a combination thereof. The second binder 3a may include a hot melt or pressure-sensitive adhesive. The second binder 3a may be an acrylic resin or a methacrylic resin. The terms "resin" and "binder" are used as alternatives and have the same meaning in this disclosure.

[0156] The second binder 3a of the second binder layer 3 can be 75-150 g / m³. 2 The amount of binder applied. In one example, the amount of binder applied can be 50-300 g / m³. 2 Within a certain range. In one example, the second binder 3a can be applied as an aqueous solution containing 50% water and 50% binder. This aqueous solution can be applied at a concentration of 150-300 g / m³. 2 The amount applied. In another example, the aqueous solution contains more than 50% water. The second binder layer 32 may also include fillers and additives.

[0157] The second binder 3a can be dried in the drying apparatus 60, for example by applying an IR to the binder 3a. After drying, the second binder 3a forms a second binder layer 3.

[0158] After the second binder 3a has dried, the core 1 on which the second binder layer 3 has been applied can be flipped over. This occurs... Figure 3 Between steps A and B. After the core 1 is flipped, the second surface 12 of the core 1, which has the second binder layer 3, faces downwards. As... Figure 3 As shown, the first surface 11 of the core 1 faces upward.

[0159] After flipping the core 1, the core 1 can be placed on the unimpregnated paper 5, as shown in step B. The unimpregnated paper 5 can be an unimpregnated cover paper. In another example, the unimpregnated paper 5 can be the type of decorative paper used in the production of laminated products, but it is not impregnated.

[0160] Unimpregnated should be understood as containing no resin or substantially no synthetic resin, for example, containing less than 10% by weight of synthetic resin, preferably less than 5% by weight, such as less than 2.5% by weight of synthetic resin. In one example, no synthetic resin is added to the paper before it is applied to the core.

[0161] Unimpregnated paper 5 can be referenced above. Figure 1 and 2 The type of description.

[0162] As an alternative or supplement, the second binder 3b may be applied to the surface of the unimpregnated paper 5, for example in a similar manner as described above, and for example in liquid form as described above. The unimpregnated paper 5 to which the second binder 3b is applied is then arranged on the second surface 12 of the core 1. The second binder 3b is disposed between the second surface 12 of the core 1 and the unimpregnated paper 5.

[0163] exist Figure 3 Step C shows the core 1, where a second binder layer 3 is applied to the second surface of the core 12 and the unimpregnated paper 5. The second binder layer 3 is disposed between the second surface 12 of the core 1 and the unimpregnated paper 5. The second binder layer 3 and the unimpregnated paper 5 are intended to form a balancing layer 20 after pressing. The balancing layer 30 is intended to balance the forces formed on the surface layer 20 during pressing, after pressing, and during mounting.

[0164] exist Figure 3 In step D, the first binder layer 2 is applied to the first surface 11 of the core 1. Figure 3 In the example shown, the first binder layer 2 is in the form of a first binder 2a applied in liquid form. The first binder 2a can be applied by a roller 70 or any other suitable application device.

[0165] The first binder 2a of the first binder layer 2 may be a thermosetting binder, such as an amino resin, such as melamine-formaldehyde resin or urea-formaldehyde resin. The first binder 2a may be urea-formaldehyde resin, phenolic resin, melamine-formaldehyde resin, polyurethane, polyester, emulsion polymer isocyanate (EPI), or a combination thereof. Alternatively, the first binder 2a may be a thermoplastic binder. Thermoplastic binders may be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyurethane (PU), polyvinyl alcohol (PVOH), polyvinyl butyral (PVB), and / or polyvinyl acetate (PVAc), or a combination thereof. The first binder 2a may include a hot melt or pressure-sensitive adhesive. The first binder 2a may be an acrylic resin or a methacrylic resin. The terms "resin" and "binder" are used as alternatives and have the same meaning in this disclosure.

[0166] The first binder 2a of the first binder layer 2 can be 75-150g / m 2 The amount of binder applied. In one example, the amount of binder applied can be 50-300 g / m³. 2Within the range. If the first binder 2a is applied as an aqueous solution containing 50% water and 50% binder. This aqueous solution can be 150-300 g / m³. 2 The amount applied. In another example, the aqueous solution contains more than 50% water. The first binder layer 2 may also contain fillers and additives.

[0167] The first binder layer 2 can be dried after application.

[0168] exist Figure 3 In step E, the wood veneer layer 4 is applied onto the first adhesive layer 2. The wood veneer layer 4 may be a flat-cut veneer, a rotary-cut veneer, a sawn veneer, and / or a semi-circular cut veneer.

[0169] Wood veneer layer 4 can be selected from oak, maple, birch, walnut, ash, and pine. Wood veneer layer 4 can have a thickness of less than 1 mm, for example, from 0.2 mm to 0.8 mm.

[0170] When the wood veneer layer 4 is applied, the first adhesive layer 2 is disposed between the first surface 11 of the core 1 and the wood veneer layer 4.

[0171] The first binder layer 2 and the wood veneer layer 4 are intended to be pressed together to form the surface layer 20.

[0172] The grain direction of the wood veneer layer 4 can be aligned with the fiber direction of the unimpregnated paper 5, such that the unimpregnated paper 5 is arranged so that the fiber direction of the unimpregnated paper 5 is substantially parallel to the grain direction of the wood veneer layer 4. "Substantially parallel" means within 25° of the parallel direction, for example, within 15° of the parallel direction.

[0173] As an alternative or supplement, the first binder 2b, in one example applied as described above, and in another example applied in liquid form, may be applied to the surface of the wood veneer layer 4. The wood veneer layer 4 may then be disposed on the first surface 11 of the core 1. The first binder 2b may be disposed between the first surface 11 of the core and the wood veneer layer 4.

[0174] When the wood veneer layer 4 has been applied onto the first adhesive layer 2, the component is pressed down, as... Figure 3 As shown in step F, the component is pressed in a fixed press 80. The wood veneer layer 4, the first binder layer 2, the core 1, the second binder layer 3, and the unimpregnated layer 5 are pressed together under pressure, preferably also under heat, to form the panel unit 10'.

[0175] The applied pressure can be in the range of 30-60 bar. The pressurization time can be 10-60 seconds. The applied temperature can be in the range of 120-250°C.

[0176] In one example, a temperature difference exists between a first pressing surface 81, intended to apply pressure to the surface layer 20, and a second pressing surface 82, intended to apply pressure to the balancing layer 30. The temperature of the first pressing surface 81 may be higher than the temperature of the second pressing surface 82. The wood veneer layer 4 of the surface layer 20 thermally insulates the first adhesive layer 2, such that the temperature at the first adhesive layer 2 is lower than the temperature at the wood veneer layer 4. To compensate for the thermal insulation effect of the wood veneer layer 4, the applied temperature may be increased. However, from the perspective of balancing the final product, the correspondingly increased temperature at the balancing layer 30 has proven to be disadvantageous.

[0177] The temperature difference between the first pressing surface 81, which is intended to press the surface layer 20 including the wood veneer layer 4, and the second pressing surface 82, which is intended to press the balancing layer 30, can be at least 10°C. This temperature difference can be less than 20°C. It can be in the range of 10-20°C.

[0178] The temperature difference between the first pressing surface 41, which is intended to press the surface layer 20 including the wood veneer layer 4, and the second pressing surface 42, which is intended to press the surface of the balancing layer 30, can be used to control the shape of the panel 100 formed by the panel unit 10 after pressing. By increasing the temperature difference, a more concave shape of the panel 100 can be obtained. If a specific shape is required, the temperature difference can be outside the range described above.

[0179] After pressing, panel unit 10' is obtained. Panel unit 10' can be divided into several individual panels 100', such as architectural panels. The width and length of such panels 100' are smaller than the width and length of panel unit 10'. For example, depending on the original size of panel unit 10' and the desired size of architectural panel 100', panel unit 10' can be divided into 1-10 panels 100', for example, each panel unit 10' can be divided into 4-6 panels 100'. Panel 100' can have a rectangular shape with opposing long side edges and opposing short side edges. Panel 100' can be architectural panels, such as floor panels, wall panels, furniture components, architectural components, worktops, etc. Panel 100' can be provided with a mechanical locking system designed for connecting panels to adjacent panels.

[0180] After pressing, the panel 100' obtained from panel unit 10' shall at least meet the requirements for wavy deformation regarding long-side wavy deformation as specified in standard SS-EN 13329:2016+A1:2018. After pressing, the panel 100' obtained from panel unit 10' shall at least meet the requirements for wavy deformation regarding short-side wavy deformation as specified in standard SS-EN 13329:2016+A1:2018. Although laminated flooring is specified, the requirements specified in this standard also apply to panels with finished surfaces. Standard SS-EN 13329:2016+A1:2018 specifies that, for laminated flooring, the wavy deformation of the upper surface of the panel at the long-side edge shall be ≤0.50% indentation and ≤1.00% protrusion. Standard SS-EN 13329:2016+A1:2018 specifies that, for laminated flooring, the wavy deformation of the upper surface of the panel at the short edge should be ≤0.15% indentation and ≤0.20% protrusion. In one example, the upper surface 11 of panel 100' at the long edge meets the requirement of less than 0.5% indentation and a maximum of 1% protrusion. In another example, the upper surface 11 of panel 100' at the short edge meets the requirement of less than 0.5% indentation and a maximum of 1% protrusion. In yet another example, the upper surface 11 of panel 100' at the short edge meets the requirement of ≤0.15% indentation and ≤0.20% protrusion. In yet another example, the short edge of the panel is substantially free of wavy deformation, i.e., close to 0 and flat, for example, with a maximum indentation of 0.15% and a maximum protrusion of 0.2%. In one example, the upper surface 11 of panel 100' has essentially no tile-like deformation at the short side edge, i.e., close to 0, for example, with a maximum of 0.15% concavity and a maximum of 0.2% protrusion, and the upper surface 11 of panel 100' has a maximum of 0.5% concavity and a maximum of 1% protrusion at the long side edge.

[0181] In this disclosure, the wood veneer layer that traditionally forms the balancing layer has been replaced by unimpregnated paper. It has been shown that the properties of unimpregnated paper can substitute for those of wood veneer panels in controlling bridging deformation. For example, the fiber orientation of the unimpregnated paper can be used to mimic the grain orientation of the wood veneer layer. Therefore, less wood can be consumed because proper balance can be achieved using a balancing layer without wood veneer panels. The use of wood veneer panels is limited to the surface of board 100' intended to be visible during installation, such as as floor paneling or the like.

[0182] Furthermore, it has been shown that replacing the wood veneer balancing layer with unimpregnated paper results in favorable corrugation of panel 100'. Short-side corrugation after pressing is close to zero. Compared to the wood veneer balancing layer, unimpregnated paper provides improved control over corrugation of panel 100'.

[0183] Figure 4 The pressed panel unit 10' or panel 100' is shown. Panel 100' can be an architectural panel, such as a floor panel, wall panel, furniture component, building component, work surface, etc.

[0184] Figure 4 Including a cross-section, the cross-sectional view of the pressed panel unit 10' corresponds to the cross-sectional view of the panel 100', which is obtained by dividing the panel unit 10' after pressing. Therefore, Figure 4 Both panel unit 10' and panel 100' can be referred to. For simplicity, in the following text, only panel unit 10' will be referred to.

[0185] The panel unit 10' includes a surface layer 20 disposed on a first surface 11 of the core 1 and a balancing layer 30 disposed on a second surface 12 of the core 1. The core 1 is as shown above. Figure 1 The type of description.

[0186] Surface layer 20 includes a wood veneer layer 4 and a first adhesive layer 2. After pressing, as... Figure 4 As shown, the first binder layer 2 can be invisible as a separate layer because during pressing, the binder 2b attaches the first surface 11 of the core to the lower surface of the wood veneer layer 4. After pressing, the binder 2b can be at least partially absorbed by the first surface 11 of the core 1 and the wood veneer layer 4.

[0187] Wood veneer layer 4 is the reference above. Figure 3 The type described. The first binder layer 2 is the reference above. Figure 3 The type described. As described above, the first binder layer 2 may include a first binder 2b, which has been applied in liquid form and subsequently dried. The first binder layer 2 is disposed between the first surface 11 of the core 1 and the wood veneer layer 4. An additional layer may be applied to the upper surface of the wood veneer layer 4. The wood veneer layer 4 may be provided with a coating, such as one or more layers of paint, or a protective layer, such as a coating layer.

[0188] The balancing layer 30 includes a second binder layer 3 and unimpregnated paper 5. The second binder layer 3 is disposed between the second surface 12 of the core 1 and the unimpregnated paper 5. After pressing, as... Figure 4 As shown, the second binder layer 3 may be invisible as a separate layer because during pressing, the second binder 3b adheres to the second surface 12 of the core 1 and to the lower surface of the wood veneer layer 4. After pressing, the second binder 3b may be at least partially absorbed by the second surface 12 of the core 1 and the unimpregnated paper 5.

[0189] The balancing layer 30 has no wood veneer panel. The type and arrangement of the unimpregnated paper 5 are as described above. Figure 3 The second binder layer 5 is as described above. Figure 3 The type described. For example, the second binder layer 3 can be applied as a second binder 3b applied in liquid form.

[0190] As described above, during the pressing process, the unimpregnated paper 5 can absorb at least some of the second binder 3b from the second binder layer 3. Therefore, the unimpregnated paper 5 may contain some resin after pressing. However, the term "unimpregnated" is intended to refer to the original composition of the paper, i.e., the composition of the paper 5 before application, as described above.

[0191] As described above, the unimpregnated paper 5 accordingly serves as the wood veneer panel arranged in the balancing layer 30. The corrugation of the panel 100' is controlled to be less than the desired value. As an example, the panel 100' can meet the corrugation requirements specified for the long side edge in SS-EN 13329:2016+A1:2018. As an example, the panel 100' can meet the corrugation requirements specified for the short side edge in SS-EN 13329:2016+A1:2018. For the short side edge of the panel 100', the corrugation requirements for the long side edge of the panel in SS-EN 13329:2016+A1:2018 can be met. For the long side edge of the panel 100', the corrugation requirements for the short side edge of the panel in SS-EN 13329:2016+A1:2018 can be met. In one example, the upper surface 11 of panel 100' has essentially no tile-like deformation at its short edge, i.e., close to zero, with, for example, ≤0.15% indentation and ≤0.20% protrusion, and the upper surface 11 of panel 100' has ≤0.50% indentation and ≤1.00% protrusion at its long edge. In another example, the tile-like deformation at the short edge of the upper surface 11 of panel 100' may have ≤0.15% indentation and ≤0.20% protrusion.

[0192] The aspect disclosed herein, which adjusts the temperature of a first pressed surface intended for a surface layer including a wood veneer layer to a higher temperature than a second pressed surface intended for a balance layer, can be combined with any type of balance layer and any type of binder layer. This aspect is not limited to balance layers including unimpregnated paper, but can be used with any type of balance layer without a wood veneer layer. The balance layer may include resin-impregnated paper, a binder layer applied in powder form, a binder layer applied in liquid form, and / or combinations thereof. The first binder layer attaching the wood veneer layer to the core can be of any type, such as including resin-impregnated paper, a binder layer applied in powder form, a binder layer applied in liquid form, and / or combinations thereof. The core may be as described above. Figure 1 and Figure 3 Publicly available types.

[0193] The temperature difference between a first pressing surface intended for pressing a surface layer including a wood veneer layer and a second pressing surface intended for pressing a balancing layer can be at least 10°C. The temperature difference can be less than 20°C. The temperature difference can be in the range of 10-20°C. As mentioned above, the temperature at the first pressing surface exceeds the temperature at the second pressing surface. The applied pressure can be in the range of 30-60 bar. The pressing time can be 10-60 seconds. The applied temperature can be in the range of 120-250°C, for example, in the range of 150-200°C, for example, 180-200°C. For example, the surface layer can be pressed at approximately 180°C, while the balancing layer can be pressed at approximately 170°C.

[0194] The surface layer of the wood veneer heat-insulates the first adhesive layer, causing the temperature at the first adhesive layer to be lower than the temperature at the wood veneer layer. To compensate for the insulation effect of the wood veneer layer, the applied temperature can be increased. However, from the perspective of balancing the final product, the corresponding temperature increase at the balancing layer has proven to be disadvantageous.

[0195] It has been shown that controlling the pressing temperature at the pressing surface facing the balance layer is beneficial for achieving a slight, waviness-like deformation of the long edges of the panel, which is desirable. During installation, the long edges of the panel are pressed down during locking and forced to be substantially flat when locked to adjacent long edges. However, if the short edges are not substantially flat, locking adjacent short edges becomes difficult. In known schemes, the effort to achieve flat short edges results in waviness-like deformation of the long edges, which is undesirable. This waviness-like deformation of the long edges can cause difficulties when locking adjacent long edges together.

[0196] The temperature difference between the first pressing surface 41, which is intended to press the surface layer 20 including the wood veneer layer 4, and the second pressing surface 42, which is intended to press the surface of the balance layer 30, can be used to control the shape of the panel 100 formed by the panel unit 10 after pressing. By increasing the temperature difference, a more concave shape can be obtained on the upper surface of the panel 100. If a specific shape is required, the temperature difference can be outside the range described above.

[0197] The pressing temperature of the first and second pressing surfaces can be in the range of 120-250°C. The pressure applied by the first and second pressing surfaces can be in the range of 30-60 bar. The pressurization time can be 10-60 seconds.

[0198] Example

[0199] Example 1A: Refer to Example

[0200] With approximately 126g / m 2A liquid solution containing melamine-formaldehyde resin, comprising 50 wt% water and 50 wt% melamine-formaldehyde, is applied to the HDF core. A 0.6 mm thick oak veneer layer is applied over the melamine-formaldehyde layer, and heat and pressure are applied to form panel units. The applied pressure is 50 bar, the temperature is 180°C, and the pressing time is 30 seconds.

[0201] After pressing, the panel unit is divided into panels with a long side length of 750mm and a short side width of 250mm. The panel does not have a balancing layer designed to balance the surface layer, which includes the wood veneer layer.

[0202] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. The tiling deformation on the upper surface of the panel along the long side was measured to be -1.762 mm, and the tiling deformation on the upper surface of the panel along the short side was measured to be -0.391 mm, as shown in Table 1. The maximum deviation from zero is recorded. Zero indicates no tiling deformation (flatness), numbers above zero indicate convex tiling deformation on the upper surface, and numbers below zero indicate concave tiling deformation on the upper surface. In this example, the upper surface of the panel exhibits concave tiling deformation on both the long and short sides.

[0203] Example 1B

[0204] At 126g / m 2 A first layer comprising a liquid solution of melamine-formaldehyde resin, having a composition of 50 wt% water and 50 wt% melamine-formaldehyde, is applied to the HDF core. An oak veneer layer with a thickness of 0.6 mm is then applied over the melamine-formaldehyde resin layer. The veneer layer and the melamine-formaldehyde resin layer form a surface layer.

[0205] The second liquid solution containing melamine-formaldehyde resin was prepared at 126 g / m³. 2 An amount of melamine-formaldehyde resin, comprising 50 wt% water and 50 wt% melamine-formaldehyde, is applied to the opposing surfaces of the HDF core. Unimpregnated cover paper is applied onto the melamine-formaldehyde resin layer. The unimpregnated paper is arranged such that the fiber direction of the unimpregnated paper is substantially parallel to the grain direction of the wood veneer layer. A second layer of melamine-formaldehyde resin and the unimpregnated cover paper form a balancing layer.

[0206] The component is pressed into a panel unit by applying heat and pressure. The applied pressure is 50 bar, the temperature at both the upper and lower pressure plates is 180°C, and the pressing time is 30 seconds. After pressing, the panel unit is divided into panels with a long side length of 750 mm and a short side width of 250 mm.

[0207] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. The tiling deformation on the upper surface of the panel was measured to be 0.220 mm at the long edge and -0.38 mm at the short edge (see Table 1). The maximum deviation from zero is recorded. Zero indicates no tiling deformation (flatness), numbers above zero indicate convex tiling deformation on the upper surface, and numbers below zero indicate concave tiling deformation. In this example, the upper surface of the panel exhibits convex tiling deformation at the long edge and concave tiling deformation at the short edge.

[0208] Example 1C

[0209] At 126g / m 2 A first layer comprising a liquid solution of melamine-formaldehyde resin, having a composition of 50 wt% water and 50 wt% melamine-formaldehyde, is applied to the HDF core. An oak veneer layer with a thickness of 0.6 mm is then applied over the melamine-formaldehyde resin layer. The veneer layer and the melamine-formaldehyde resin layer form a surface layer.

[0210] At 126g / m 2 A second layer of liquid solution containing melamine-formaldehyde resin, comprising 50% by weight water and 50% by weight melamine-formaldehyde, is applied to the opposing surface of the HDF core. Unimpregnated decorative paper is then applied onto the melamine-formaldehyde resin layer. The unimpregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the wood veneer layer. The second layer of melamine-formaldehyde resin and the unimpregnated decorative paper form a balancing layer.

[0211] The component is pressed into a panel unit by applying heat and pressure. The applied pressure is 50 bar, the temperature at both the upper and lower pressure plates is 180°C, and the pressing time is 30 seconds. After pressing, the panel unit is divided into panels with a long side length of 750 mm and a short side width of 250 mm.

[0212] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. The tiling deformation on the upper surface of the panel at the long edge was measured to be 0.244 mm, and the tiling deformation on the upper surface of the panel at the short edge was measured to be -0.28 mm, as shown in Table 1. The maximum deviation of the measurement from zero is indicated. Zero represents no tiling deformation (flatness), numbers above 0 represent convex tiling deformation on the upper surface, and numbers below 0 represent concave tiling deformation on the upper surface. In this example, the upper surface of the panel exhibits convex tiling deformation at both the long and short edges.

[0213] Example 2A: Refer to Example

[0214] Resin-impregnated decorative paper containing melamine-formaldehyde resin was applied to the HDF core. A 0.6 mm thick oak veneer layer was then applied to the resin-impregnated paper, and heat and pressure were applied to form panel units. The applied pressure was 50 bar, the temperature was 180°C, and the pressing time was 30 seconds.

[0215] After pressing, the panel unit is divided into panels with a long side length of 750mm and a short side width of 250mm. The panel does not have a balancing layer designed to balance the surface layer, which includes the wood veneer layer.

[0216] After pressing and cooling to ambient temperature (approximately 20°C), the tack deformation was measured on one of the panels. The tack deformation on the upper surface of the panel was measured to be -2.069 mm on the long side and -0.479 mm on the short side (see Table 1). The maximum deviation from zero is recorded. Zero indicates no tack deformation (flatness), numbers above zero indicate convex tack deformation on the upper surface, and numbers below zero indicate concave tack deformation on the upper surface. In this example, the upper surface of the panel exhibits concave tack deformation on both the long and short sides.

[0217] Example 2B

[0218] A first resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the upper surface of the HDF core. A 0.6 mm thick oak veneer layer is then applied onto the first resin-impregnated paper. The first resin-impregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the veneer layer. The veneer layer and the first resin-impregnated paper form a surface layer.

[0219] Decorative paper impregnated with a second resin, comprising melamine-formaldehyde resin, was applied to the lower surface of the HDF core. The corresponding binding dose was 126 g / m². 2 Unimpregnated decorative paper is applied onto a second resin-impregnated paper. The unimpregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the wood veneer layer. The second resin-impregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the wood veneer layer. The second impregnated paper and the unimpregnated paper form a balanced layer.

[0220] The component is pressed into a panel unit by applying heat and pressure. The applied pressure is 50 bar, the temperature at both the upper and lower pressure plates is 180°C, and the pressing time is 30 seconds. After pressing, the panel unit is divided into panels with a long side length of 750 mm and a short side width of 250 mm.

[0221] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. The tiling deformation on the upper surface of the panel at the long edge was measured to be 1.281 mm, and the tiling deformation on the upper surface of the panel at the short edge was measured to be 0.033 mm, as shown in Table 1. The maximum deviation of the measurement from zero is indicated. Zero represents no tiling deformation (flatness), numbers above zero represent convex tiling deformation on the upper surface, and numbers below zero represent concave tiling deformation on the upper surface. In this example, the upper surface of the panel exhibits convex tiling deformation at both the long and short edges.

[0222] Example 2C

[0223] A first resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the upper surface of the HDF core. A 0.6 mm thick oak veneer layer is then applied onto the first resin-impregnated paper. The first resin-impregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the veneer layer. The veneer layer and the first resin-impregnated paper form a surface layer.

[0224] A second resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the lower surface of the HDF core. Unimpregnated decorative paper is then applied onto the second resin-impregnated paper. The unimpregnated paper is arranged such that its fiber direction is substantially transverse to the grain direction of the wood veneer layer. The second resin-impregnated paper is arranged such that its fiber direction is substantially parallel to the grain direction of the wood veneer layer. The second impregnated paper and the unimpregnated paper form a balancing layer.

[0225] The component is pressed into a panel unit by applying heat and pressure. The applied pressure is 50 bar, the temperature at both the upper and lower pressure plates is 180°C, and the pressing time is 30 seconds. After pressing, the panel unit is divided into panels with a long side length of 750 mm and a short side width of 250 mm.

[0226] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. Referring to Table 1, the tiling deformation on the upper surface of the panel, measured at the long side edge, was 0.912 mm, and at the short side edge, it was 0.031 mm. The maximum deviation from zero is recorded. Zero indicates no tiling deformation (flatness), numbers above zero indicate convex tiling deformation on the upper surface, and numbers below zero indicate concave tiling deformation on the upper surface. In this example, the upper surface of the panel exhibits convex tiling deformation at both the long and short sides.

[0227] Example 3A: Refer to Example

[0228] A first resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the HDF core. A 0.6 mm thick oak veneer layer is then applied to the resin-impregnated paper. The oak veneer layer and the first resin-impregnated paper form the surface layer.

[0229] A second resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the lower surface of the HDF core. The second impregnated paper forms a balancing layer.

[0230] The applied pressure was 50 bar, the temperature was 180°C, and the pressing time was 30 seconds. The panel unit was divided into panels with a long side length of 750 mm and a short side width of 250 mm. The pressure plate facing the surface layer and the pressure plate facing the balance layer were at approximately the same temperature, i.e., both pressure plates had a temperature of 180°C.

[0231] After pressing, the panel unit is divided into panels with a long side length of 750mm and a short side width of 250mm.

[0232] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. Referring to Table 1, the tiling deformation on the upper surface of the panel, measured at the long edge, was 0.613 mm, and at the short edge, it was 0.043 mm. The maximum deviation from zero is recorded. Zero indicates no tiling deformation (flatness), numbers above zero indicate convex tiling deformation on the upper surface, and numbers below zero indicate concave tiling deformation. In this example, the upper surface of the panel exhibits convex tiling deformation at both the short and long edges.

[0233] Example 3B

[0234] A first resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the HDF core. A 0.6 mm thick oak veneer layer is then applied to the resin-impregnated paper. The oak veneer layer and the first resin-impregnated paper form the surface layer.

[0235] A second resin-impregnated decorative paper containing melamine-formaldehyde resin is applied to the lower surface of the HDF core. The second impregnated paper forms a balancing layer.

[0236] The applied pressure is 50 bar, and the pressing time is 30 seconds. The panel unit is divided into panels with a long side length of 750 mm and a short side width of 250 mm. The temperature of the pressing plate facing the surface layer is approximately 180°C. The temperature of the pressing plate facing the surface layer is approximately 170°C.

[0237] After pressing, the panel unit is divided into panels with a long side length of 750mm and a short side width of 250mm.

[0238] After pressing and cooling to ambient temperature (approximately 20°C), the tiling deformation was measured on one of the panels. The tiling deformation of the upper surface of the panel at the long edge was measured to be 0.110 mm, and the tiling deformation of the upper surface of the panel at the short edge was measured to be -0.216 mm, as shown in Table 1. The maximum deviation from zero is recorded. Zero indicates no tiling deformation (flatness), numbers above zero indicate convex tiling deformation of the upper surface, and numbers below zero indicate concave tiling deformation of the upper surface. In this example, the upper surface at the short edge exhibits slight concave tiling deformation, while the upper surface at the long edge exhibits convex tiling deformation.

[0239] Table 1

[0240]

[0241] The degree of tile-like deformation, expressed as a percentage, is calculated by dividing the maximum long / short side measurement by the length of the long / short side, and expressed as a percentage.

Claims

1. A method for producing panel units (10; The method of 10'), wherein the panel unit is configured to be divided into individual floor panels, the method comprising: A core (1) is provided having a first surface (11) and a second surface (12) opposite to the first surface (11), the core being a wood substrate; A surface layer (20) is applied to the first surface (11) of the core (1), the surface layer (20) comprising a wood veneer layer (4) and a first adhesive layer (2) for attaching the wood veneer layer (4) to the first surface (11) of the core (1); A balancing layer (30) is applied to the second surface (12) of the core (1), the balancing layer (30) comprising unimpregnated paper (5) and a second binder layer (3) for attaching the unimpregnated paper (5) to the second surface (12) of the core (1), wherein the fiber direction of the unimpregnated paper (5) is oriented substantially parallel to the grain direction of the wood veneer layer (4); Heat and pressure are applied to the surface layer (20), the balancing layer (30), and the core (1) to form the panel unit (10; 10'). The unimpregnated paper (5) is paper that has not been impregnated with resin and contains at least 80% by weight of α-cellulose. The unimpregnated paper (5) is unimpregnated decorative paper or unimpregnated cover paper.

2. The method according to claim 1, wherein, The balancing layer (30) consists of the unimpregnated paper (5) and the second binder layer (3).

3. The method according to claim 1 or 2, wherein, After pressing, the unimpregnated paper (5) forms the lowermost surface of the panel unit (10; 10′).

4. The method according to claim 1 or 2, wherein, The balancing layer (30) does not contain a wood veneer layer.

5. The method according to claim 1 or 2, wherein, The second binder layer (3) is applied in liquid form.

6. The method according to claim 1 or 2, wherein, The second binder layer (3) is a second resin-impregnated paper (3a) disposed between the second surface (12) of the core (1) and the unimpregnated paper (5).

7. The method according to claim 6, wherein, The fiber direction of the second resin-impregnated paper is substantially parallel to the grain direction of the wood veneer layer.

8. The method according to claim 1 or 2, wherein, The first binder layer (2) is applied in liquid form.

9. The method according to claim 1 or 2, wherein, The first binder layer (2) is a first resin-impregnated paper (2a) disposed between the wood veneer layer (4) and the first surface (11) of the core (1).

10. The method according to claim 1 or 2, wherein, Applying pressure includes pressing the surface layer at a first temperature and pressing the balance layer at a second temperature, wherein the second temperature is lower than the first temperature.

11. The method according to claim 1 or 2, further comprising dividing the panel unit (10; 10') into individual panels (100; 100') after pressing, wherein the tile-like deformation of the short side edge of the panel is less than 0.2% of the width of the short side edge of the panel.

12. The method of claim 1 or 2, further comprising dividing the panel unit (10; 10') into individual panels (100; 100') after pressing, wherein the tile-like deformation of the short side edge of the panel is in the range of -0.15% to 0.2% of the width of the short side edge of the panel.

13. A floor panel (100; 10) 0'), including: A core (1) having a first surface (11) and a second surface (12) opposite to the first surface (11), the core being a wood substrate; A surface layer (20) disposed on the first surface (11) of the core (1), the surface layer (20) comprising a wood veneer layer (4) attached to the core (1) by a first adhesive layer (2); A balancing layer (30) is disposed on the second surface (12) of the core (1), the balancing layer (30) comprising unimpregnated paper (5) attached to the core (1) by a second binder layer (3), wherein the fiber direction of the unimpregnated paper (5) is substantially parallel to the grain direction of the wood veneer layer (4). The unimpregnated paper (5) is paper that has not been impregnated with resin and contains at least 80% by weight of α-cellulose. The unimpregnated paper (5) is unimpregnated decorative paper or unimpregnated cover paper.

14. The floor panel according to claim 13, wherein, The balancing layer (30) consists of the unimpregnated paper (5) and the second binder layer (3).

15. The floor paneling according to claim 13 or 14, wherein, The unimpregnated paper (5) forms the lowermost surface of the panel (100; 100').

16. The floor paneling according to claim 13 or 14, wherein, The balancing layer (30) does not contain a wood veneer layer.

17. A method for producing panel units (10; The method of 10'), wherein the panel unit is configured to be divided into individual floor panels, the method comprising: A core (1) is provided having a first surface (11) and a second surface (12) opposite to the first surface (11), the core being a wood substrate; A surface layer (20) is applied to the first surface (11) of the core (1), the surface layer (20) comprising a wood veneer layer (4) and a first adhesive layer (2) for attaching the wood veneer layer (4) to the first surface (11) of the core (1); A balancing layer (30) is applied to the second surface (12) of the core (1), wherein the balancing layer (30) comprises an unimpregnated paper (5) and a second binder layer (3); Heat and pressure are applied to the surface layer (20), the balancing layer (30), and the core (1) to form the panel unit (10; 10'). The application of heat and pressure includes pressing the surface layer (20) at a first temperature and pressing the balancing layer (30) at a second temperature, wherein the second temperature is lower than the first temperature. The unimpregnated paper (5) is paper that has not been impregnated with resin and contains at least 80% by weight of α-cellulose. The unimpregnated paper (5) is unimpregnated decorative paper or unimpregnated cover paper.

18. The method according to claim 17, wherein, The temperature difference between the first temperature and the second temperature is at least 10°C.

19. The method according to claim 18, wherein, The temperature difference is less than 20℃.

20. The method according to any one of claims 17-19, wherein, The second binder layer (3) is applied in liquid form.

21. The method according to any one of claims 17-19, wherein, The second binder layer (3) is a second resin-impregnated paper (3a) disposed between the second surface (12) of the core (1) and the unimpregnated paper (5).

22. The method according to any one of claims 17-19, wherein, The first binder layer (2) is a first resin-impregnated paper (2a) disposed between the wood veneer layer (4) and the first surface (11) of the core (1).

23. The method according to any one of claims 17-19, wherein, The first binder layer is applied in liquid form.

24. The method according to any one of claims 17-19, wherein, The balancing layer (30) does not contain a wood veneer layer.

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