Decorative panel, core layer and method for producing said panel

Abstract

The invention relates to a decorative panel, in particular a decorative floor panel, a decorative ceiling panel or a decorative wall panel, comprising: at least one core layer; a decorative top structure secured directly or indirectly to a top surface of the core layer. The invention also relates to a core layer for use in a decorative panel according to the invention. The invention also relates to a method for producing a decorative panel, in particular a decorative panel according to the invention.

Description

Technical Field

[0001] The invention relates to a decorative panel, in particular a decorative floor panel, a decorative ceiling panel or a decorative wall panel, comprising: at least one core layer; a decorative top structure fixed directly or indirectly to the top surface of the core layer. The invention also relates to a core layer for use in a decorative panel according to the invention. The invention also relates to a method for producing a decorative panel, in particular a decorative panel according to the invention. Background Art

[0002] During the last decades, many improvements have been observed in the field of decorative panels, such as floor panels and wall panels. These improvements cover various aspects of decorative panels, such as improving the aesthetic appearance of the panels, improving the mechanical connection profile of the panels, improving the acoustic performance of the panels, improving the scratch resistance of the panels and improving the core composition of the panels. Regarding the latter aspect, a trend can be seen, that is, traditional core materials such as medium density fiberboard (MDF) and high density fiberboard (HDF) have been partially replaced by other materials such as compositions based on polyvinyl chloride (PVC). In contrast to MDF and HDF, PVC is waterproof and therefore easy to maintain, and it also shows relatively attractive noise reduction properties. However, the use of PVC in the core composition of decorative panels is not uncontroversial. Since this PVC is usually softened by using dangerous plasticizers (such as phthalates), it may involve health risks. In addition, toxic chemicals are used in the production process of PVC and toxic by-products and waste are generated. Furthermore, in the event of a fire, PVC-based panels may generate carcinogens called dioxins and furans, which are less desirable from a health safety and environmental point of view. Apart from this, the carbon footprint of PVC (also known as embodied carbon) is substantial, which also puts pressure on the use of PVC in the core layer of decorative panels. With the increasing awareness of health safety and environment of materials, the industry and its customers are also demanding the use of alternative raw materials for the manufacture of decorative panels. More specifically, there is a need to develop a core composition for decorative panels that is relatively health and safety and has a significantly reduced carbon footprint to protect the environment as much as possible. Summary of the invention

[0003] It is therefore a first object of the present invention to provide a decorative panel having a relatively low carbon footprint.

[0004] Therefore, a second object of the present invention is to provide a decorative panel having an improved core composition.

[0005] Therefore, a third object of the present invention is to provide a decorative panel having a core composition that is healthier, safer and / or more environmentally friendly.

[0006] Therefore, a fourth object of the present invention is to provide a decorative panel that is free of PVC.

[0007] At least one of these objects may be achieved by providing a decorative panel according to the preamble, the decorative panel comprising:

[0008] at least one core layer;

[0009] a decorative top structure secured directly or indirectly to the top surface of the core layer;

[0010] wherein the at least one core layer comprises at least one chain-extended polycondensate, preferably at least one chain-extended polyester, more preferably at least one chain-extended polyethylene terephthalate (PET), at least partially composed of polycondensate-based molecules, preferably polyester-based molecules, more preferably polyethylene terephthalate (PET)-based molecules, wherein each molecule comprises at least two polymer chains composed of recycled polycondensate, preferably recycled polyester, more preferably recycled PET, and the polymer chains are chemically bonded to each other via at least one chain extender.

[0011] The decorative panel according to the present invention has a number of advantages. First, since the material composition of the core layer is based on recycled polycondensates, preferably recycled polyesters, more preferably recycled PET, the carbon footprint of the core composition and therefore the carbon footprint of the decorative panel itself can be significantly reduced, especially compared to the original fossil-based polymers (which are based on non-renewable fossil fuels). In addition, compared to PVC, these recycled polymers are relatively healthy and safe, because these polymers do not require dangerous plasticizers such as phthalates to make the polymers more flexible for target applications. In addition, the production of polycondensates such as polyesters, preferably PET (contrary to PVC) does not lead to toxic by-products, and these polycondensates (contrary to PVC) do not release extremely strong carcinogens, i.e. dioxins and furans, in the event of a fire. Therefore, (recycled) polycondensates (preferably polyesters, more preferably PET) have significant advantages over PVC, and the use of recycled materials further reduces the embodied carbon (carbon footprint) of the core composition, and therefore reduces the embodied carbon (carbon footprint) of the decorative panel itself. In order to keep the carbon footprint of the core composition and hence the decorative panel as limited as possible, it may be preferred that the core layer is free of virgin fossil based polymers. It may also be preferred that the core layer is free of polyvinyl chloride (PVC).

[0012] Compared to PVC, PET has the advantage of being more rigid and more thermally stable. In case the decorative panels are exposed to sunlight, the panel temperature can easily exceed 50 degrees Celsius, which usually leads to deformation of PVC-based panels, while the more heat-resistant panels according to the invention can prevent such deformation. Furthermore, the panels according to the invention are also relatively water- and moisture-proof (contrary to MDF and HDF), which leads to an additional major advantage of the decorative panels according to the invention over conventional panels.

[0013] During thermomechanical processing, PET is subjected to high temperature and shear stress conditions that can cause severe degradation of the PET in terms of molar mass and (interrelated) viscosity. Virgin PET typically has a molar mass between 20,000 and 30,000 g / mol, while recycled PET typically has a molar mass between 10,000 and 20,000 g / mol. The water (and / or PVC (present in trace amounts)) present in the recycled PET material produces PET chain scission during normal extrusion. At processing temperatures (270-290 degrees Celsius), a hydrolysis reaction occurs between water and PET, producing shorter chains with carboxyl and hydroxyl end groups. Thermal cleavage of PET ester bonds results in PET chains with carboxyl and vinyl ester end groups. Broken PET chains (PET with reduced molar mass) are less ideal for use in decorative panels. In order to increase the molar mass of PET and / or the viscosity of PET to a higher level for use in decorative panels, the broken PET chains are chemically bonded (reconnected) by one or more chain extenders, which is preferably achieved by reactive extrusion. These chain extenders are preferably bifunctional or multifunctional chain extenders because of their high reaction rate without producing (undesirable) by-products (possibly except water). In this way, PET with a higher (average) molar mass can be produced, and therefore with a higher viscosity, preferably at least 0.8 dl / g, to allow or improve the manufacture of the core layer, and therefore the manufacture of the decorative panel itself. Before chain extension, the recycled PET used as a raw material for constituting the core composition preferably has a viscosity of 0.5 dl / g to 0.6 dl / g. This viscosity will increase to a value of at least 0.8 dl / g (and preferably less than 1.0 dl / g) during chain extension (usually during reactive extrusion). Preferably, the core layer and / or the decorative panel are substantially free of PVC to reduce the carbon footprint of the decorative panel. It is conceivable, but not essential, that the core layer and / or the decorative panel is substantially free of virgin PET to reduce the carbon footprint of the decorative panel.The viscosity is preferably measured by applying Chinese standard T / CCFA00011-2021, which requires a test temperature of 25 degrees Celsius.

[0014] It may be preferred that at least a portion of the PET-based molecules each comprises at least three or at least four polymer chains consisting of recycled PET, which are chemically bonded to each other via at least one chain extender. This can be achieved, for example, by applying a tetrafunctional chain extender such as pyromellitic dianhydride (PMDA). In the latter example, the PMDA chain extender forms a molecular center to which (the outer ends of) four chains of preferably recycled PET are chemically bonded. It is also conceivable that at least a portion of the PET-based molecules each comprises more than four polymer chains consisting of recycled PET, which are chemically bonded to each other via at least one chain extender. This can be achieved, for example, by using a combination of different chain extenders. By increasing the number of reconnected PET chains, the molar mass of the extended PET can be increased, and therefore its viscosity, to obtain the desired properties for manufacturing (and / or use).

[0015] It is conceivable, but not necessary, that the core layer and / or the decorative panel are substantially free of virgin PET, in order to reduce the carbon footprint of the decorative panel. However, it is also conceivable that the material composition of at least one core layer comprises virgin PET, preferably in addition to recycled PET. Since such virgin PET has the same functional end groups compared to recycled PET, it is also possible and likely that virgin PET will be part of molecules based on chain-extended PET. Therefore, it is conceivable that the core layer comprises chain-extended PET consisting at least partially of PET-based molecules, wherein each molecule comprises at least one polymer chain consisting of recycled PET and at least one polymer chain consisting of virgin PET chemically bonded to each other via at least one chain extender. In order to efficiently process a mixture of virgin PET and recycled PET, in particular by using an extruder, the two raw materials are preferably selected or chosen such that their melting points are substantially the same or close to each other. Preferably, the difference in melting point between the selected virgin PET and the selected recycled PET is less than 10 degrees Celsius, more preferably less than 5 degrees Celsius, even more preferably less than 3 degrees Celsius.

[0016] Typically, the length and therefore also the molar mass of the recycled PET chains is (much) smaller than that of the virgin PET chains. The molar mass of the recycled PET is preferably at least 10,000 g / mol and typically less than 20,000 g / mol, whereas the molar weight of the virgin PET is typically between 20,000 g / mol and 30,000 g / mol. Depending on the number of (re)connected PET chains in the chain-extended PET molecule, the molar mass of these modified chain-extended PET molecules is preferably more than 20,000 g / mol, and may even be more than 30,000 g / mol, 40,000 g / mol and / or 50,000 g / mol, but is preferably less than 100,000 g / mol to ensure a sufficiently low viscosity to allow proper extrusion of the chain-extended PET material. The reconnection of the PET chains typically occurs within the extruder and is considered to be a chemical reaction between the PET chains and at least one chain extender. Optionally, water molecules are produced during this reaction. Depending on the properties of the recycled PET used as feedstock, in particular the average chain length, the type and amount of chain extender can be selected to achieve a preferred molar mass and thus viscosity for proper processing of the material based on the modified, chain-extended PET.

[0017] It is conceivable that not all of the raw materials initially present in the masterbatch to be extruded will react during the reactive extrusion process. Thus, it is conceivable that the core layer comprises unbound recycled PET and / or unbound virgin PET (if applicable, and / or wherein the core layer comprises unbound chain extender molecules).

[0018] As mentioned above, it is conceivable and even preferred that the core layer comprises a chain-extended polyethylene terephthalate (PET) at least partially composed of polyethylene terephthalate (PET)-based molecules, wherein each molecule comprises at least two polymer chains composed of recycled PET chemically bonded to each other via at least two different chain extenders. This can increase the number of chemically bonded PET chains in a single molecule, which can increase the molar mass and viscosity of the core layer composition during extrusion.

[0019] At least one chain extender may be or may include at least one multifunctional epoxide oligomer. Prior to bonding to the PET chain, the multifunctional epoxide oligomer may be represented by the following chemical structure:

[0020] in:

[0021] R1 to R5 are H, CH 3 , higher alkyl or a combination thereof;

[0022] R6 is alkyl; and

[0023] x, y and z are each between 1 and 20.

[0024] This solid multifunctional epoxide oligomer is also known as ADR-4368 (from BASF), abbreviated as "ADR".

[0025] ADR has at least four functional groups and can rapidly bond to at least four PET chains, as shown below:

[0026] Additionally or alternatively, before bonding to the PET chain, at least one chain extender may be or may comprise at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA). PMDA (1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetraone) is represented by the following chemical structure:

[0027] MEDA (1,2:3,4-benzenetetracarboxylic anhydride) can be represented by the following chemical structure:

[0028] Both dianhydrides are tetrafunctional and are capable of chemically bonding four PET chains each. Typically, this bonding process constitutes a two-stage reaction mechanism, where in the first rapid reaction step, two PET chains are chemically bonded to the dianhydride, such as PMDA, as shown below:

[0029] In a second, slower reaction step, two additional PET chains are chemically bonded or capable of chemically bonding to the dianhydride:

[0030] In this second reaction step, a water molecule is produced. This results in a chain-extended PMDA-PET molecule with four PET arms.

[0031] It is conceivable, and perhaps even preferred, that the core layer comprises: (i) at least one (bonded) dianhydride, preferably (bonded) pyromellitic dianhydride (PMDA) and / or (bonded) metamellitic dianhydride (MEDA) and (ii) (bonded) ADR 4368 (from BASF; see above). Preferably, the dianhydride and The mass ratio between ADR 4368 and PMDA is between 1:1 and 2:1; more preferably, the mass ratio is 6:4. The molar mass of ADR is about 6800 g / mol and the molar mass of PMDA is 218.12 g / mol. By applying this balanced ratio, the molar mass of the chain-extended PET molecule is high enough to achieve the desired viscosity for extrusion purposes, while being low enough or limited enough to prevent the viscosity from becoming too high for extrusion. By applying this chain extender mixture, more comprehensive molecules (molecular complexes) can be achieved, such as Figure 8 As shown, each molecule can have at least eight PET chains. In this reaction, each PMDA molecule reacts with four PET chains (as described above), and then each four-arm PMDA-PET molecule chemically bonds with ADR to produce ADR-(PMDA-PET) n Numerator, where n ≥ 2, such as Figure 8 Other variations are also conceivable. ADR-(PMDA-PET) n The presence of the molecule may be combined with the presence of an ADR-PET molecule and / or the presence of a PMDA-PET molecule as described above. Thus, in more general terms, it is conceivable that at least a portion of the PET-based molecules each comprise:

[0032] a plurality of clusters, wherein each cluster comprises a plurality of polymer chains composed of recycled PET chemically bonded to each other via dianhydrides, preferably PMDA and / or MEDA;

[0033] The clusters are chemically bonded to each other via the multifunctional epoxide oligomer.

[0034] Additionally or alternatively, at least one chain extender comprises bis-(2,4-di-tert-butylphenol)pentaerythritol diphosphite (available from Ciba Specialty Chemicals 126) or formed thereof. In addition to one or more primary chain extenders, such as one or more of the above-mentioned chain extenders, the chain extender can also be used as a secondary chain extender. 126 can be represented by the following chemical formula:

[0035] During the chain extension reaction with PET, The 126 molecule will be cut into two 126 fragments, each of which is able to chemically bond to three PET chains (PET molecules). Here, the molar mass of the chain-extended PET molecules also increases depending on the concentration of the chain extender, while the crystallinity tends to lower values.

[0036] The use of one or more additional or alternative chain extenders is also conceivable. For example, the chain extender may be an epoxy chain extender comprising at least one epoxide group such as 2-methyl-oxirane methyl ester. Such epoxy chain extenders are generally suitable for ring-opening polymerization with (recycled) PET chains.

[0037] The amount of chain-extended polyethylene terephthalate (PET) in the core layer is preferably between 25% and 45%, preferably between 30% and 35%, by weight of the core layer. The amount of chain extender in the core layer is preferably between 0.25% and 4%, preferably between 0.5% and 1%, by weight of the core layer. The remainder of the core layer is typically formed by one or more fillers and / or one or more functional additives, as described below.

[0038] In an embodiment of the decorative panel according to the invention, the panel comprises a plurality of laminated core layers, wherein at least one core layer, and preferably at least two core layers or even each core layer comprises PET, preferably recycled PET, more preferably extended (recycled) PET. At least one of the core layers may be a reinforcing layer, such as a glass fiber layer. The core layers comprising recycled PET may have different compositions or may have the same composition. The core layers may be manufactured by coextrusion, in particular reactive coextrusion, wherein preferably during the (co)extrusion process the recycled PET chains are extended by using one or more chain extenders. In a preferred embodiment, the panel comprises at least three laminated core layers in an alternating configuration, wherein core layers having substantially the same composition surround core layers having different compositions. Such an alternating configuration may, for example, be an ABA configuration, wherein the outer layer (A) has substantially the same composition, while the inner layer (B) has a different composition. The outer layer (A) preferably has a lower viscosity than the inner layer (B). This has a dual advantage. The first advantage is that the lower viscosity results in a relatively smooth surface of the outer layer (A), which facilitates easy application of a decorative top structure on top, including, for example, a digitally printed decorative layer. Preferably, at least one of these outer layers (A) is solid (unfoamed). The second advantage of providing a higher viscosity for the inner layer (B) is that it allows more fillers, such as limestone, to be applied in the layer (B), which reduces the cost price of the inner layer (B). In addition, the inner layer (B) can be a foamed layer, which reduces the density and generally improves the sound damping properties and / or comfort of the decorative panel itself. Therefore, at least one core layer can be unfoamed, and / or at least one core layer can be foamed. The thickness of each outer core layer (A) can be less than the thickness of the inner core layer (B), and it can also lead to a situation where the total thickness of the outer core layer (A) (sum) is less than the thickness of the inner core layer (B). Alternative configurations are also conceivable. It is conceivable that only a single core layer is applied, which can be foamed or unfoamed. It is conceivable that at least one core layer, for example the inner core layer (B), comprises recycled PET, while another core layer, for example at least one outer core layer (A), comprises PETG (polyethylene terephthalate) and / or another core layer comprises virgin PET. Such AB and / or ABA and / or (AB) n (wherein n>1) configuration can be realized by coextrusion, particularly due to the structural similarity between PET and PETG. It has been found that, compared with PET, PETG is more suitable for use as a supporting layer and / or adheres to the decorative top structure and / or UV curing layer applied on the PETG layer. Due to the improved adhesive properties of PETG, it may no longer be necessary to apply a separate adhesive layer above the PETG layer to realize reliable and durable connection between core layer and the decorative structure. The type of filler (such as calcium carbonate) can be identical for each core layer, or alternatively, also can be different between at least two core layers.

[0039] Preferably, the mutually bonded recycled PET chains forming part of the chain-extended PET molecule and therefore also the original recycled PET material used to form the chain-extended PET molecule each have an average molar mass of less than 20,000 g / mol, preferably less than 15,000 g / mol, more preferably less than 12,000 g / mol. Preferably, this average molar mass is higher than 10,000 g / mol to ensure a sufficiently high viscosity and is preferably at least 0.5 dl / g. Depending on the number of PET chains to which the at least one chain extender used is bonded (and depending on the molar mass of the chain extender used), the molar mass of the molecules based on the chain-extended PET is approximately a multiple of these preferred values.

[0040] The core layer preferably comprises at least one inorganic filler (e.g. limestone) and / or organic filler (e.g. wood particles). Typically, the chain-extended PET molecules form a polymer matrix in which one or more additives are dispersed. Other possible inert and / or functional fillers are, for example: chalk, calcined clay, glass particles, glass fibers, carbon particles, silicon particles, (another) mineral filler, rice, (another) natural filler, (another) (auxiliary) polymer, such as elastomer and / or latex. These fillers are usually used to reduce the cost price of the core layer and / or to make the core layer more flexible or more rigid (rigid). The amount of filler in the core layer is preferably at least 50% by weight of the core layer, preferably 60% to 70% by weight of the core layer. Preferably, the weight of filler in the core layer is at least 1.5 times the weight of PET, preferably chain-extended PET, of the core layer. The presence of a relatively large proportion (≥ weight percentage) of filler in the core layer leads to a relatively large distance between the recycled PET molecules originally present in the masterbatch (fed into the extruder for extrusion). In order to improve the chain extension process during reactive extrusion, it is preferred to add an excess of chain extender, such as PMDA, to the masterbatch. This will increase the reactivity and thus the yield of the chain extension process during masterbatch processing.

[0041] It may be preferred that the core layer comprises at least one lubricant configured to withstand temperatures of at least 200 degrees Celsius, preferably at least 255 degrees Celsius (which corresponds roughly to the melting temperature of recycled PET), more preferably at least 280 degrees Celsius (which corresponds roughly to the extrusion temperature). The lubricant is preferably present in an amount of less than 1% by weight of the core layer. Typically, extrusion occurs at these higher temperatures (>200 degrees Celsius). The main role of the lubricant is to reduce friction, minimize wear, and prevent overheating of parts during extrusion. Preferably, the core layer comprises at least one lubricant formed by silicone oil, and preferably, the amount of the lubricant is less than 1% by weight of the core layer. Silicone oil is an example of a lubricant that can withstand extrusion temperatures of at least 200 degrees Celsius, as opposed to, for example, ordinary waxes.

[0042] The core layer preferably comprises at least one toughening agent, the amount of which is preferably less than 10% by weight of the core layer, more preferably 3% to 8% by weight of the core layer. The toughening agent can be formed, for example, from a styrene-ethylene-butylene-styrene terpolymer (SEBS-g-MA) functionalized with maleic anhydride (e.g., FG1901X obtained from KRATON Corporation). Such a toughening agent can reduce the melt flow index (MFI) of a masterbatch based on recycled PET to a value of, for example, about 50 g / 10 min during extrusion, which is beneficial to the production of the core layer.

[0043] The decorative top structure preferably comprises a primer layer applied to the top surface of the core layer and at least one further layer applied to the primer layer. The primer may for example contain calcium carbonate and / or hydrogenated castor oil, and wherein preferably the adhesive primer is a two-component adhesive, for example based on a (polyether) polyol and a curing agent. The primer layer helps to adhere another layer (for example a base coating) to the core layer.

[0044] The decorative top structure may include at least one base coating applied directly or indirectly to the top surface of the core layer, and at least one additional layer applied to the base coating. The base coating is generally configured to provide a substrate for applying a decorative layer. At least one base coating is preferably a white layer, which will improve the color authenticity of the decorative layer optionally digitally printed above the base coating. The white base coating may be a UV curing layer. The white base coating may, for example, contain unsaturated aliphatic polyurethane acrylate and / or hydroxyethyl methacrylate and / or titanium dioxide. The white base coating may be covered by another base coating to balance the surface tension, thereby preventing the shrinkage of the ink droplets optionally printed on the base coating. The additional base coating may be a UV curing layer. The additional base coating may, for example, contain unsaturated aliphatic polyurethane acrylate and / or hydroxyethyl methacrylate and / or calcium carbonate and / or silicon dioxide.

[0045] The decorative top structure generally comprises at least one decorative layer applied directly or indirectly to the top surface of the core layer, and preferably comprises at least one further layer applied to the decorative layer, such as a wear-resistant layer and / or an anti-scratch layer. The decorative layer is preferably a digitally printed decorative layer, but may also be formed by a veneer layer (wood layer, stone layer, polymer layer, other synthetic layer or natural layer), or by a decorative, preferably polymer-based film, such as a film comprising PET, in particular a film comprising recycled PET and / or a film comprising PETG. The wear-resistant layer and the anti-scratch layer (which are preferably used as a top coating) are preferably at least partially transparent and / or translucent UV-cured layers. Additionally or alternatively, at least one wear-resistant layer and / or at least one anti-scratch layer comprises PET, wherein the thickness of the PET may be in the range of 10 μm to 100 μm. The wear-resistant layer and / or the anti-scratch layer comprising PET may be a film comprising PET. Such a film has excellent transparency, heat resistance, durability and chemical resistance.

[0046] The top surface of the decorative top structure is provided with a relief pattern, also called an embossed structure, wherein the relief pattern is preferably aligned with the decorative image of the decorative layer. The relief pattern may be initially provided in one of the wear layers or in another intermediate layer and may be covered by the top coating so that the relief of the relief pattern remains visible and / or perceptible at least partially at the top surface of the decorative top structure.

[0047] It is conceivable that the decorative top structure comprises and / or is formed by a single embossed wear layer, preferably comprising PET and / or PETG, wherein the wear layer is provided with a decorative print on its lower side (facing the core layer). The decorative print can simply be a decorative ink layer or can be a separate decorative film. The embossing applied in or on the wear layer is preferably aligned with the decorative print. In this way, a relatively compact, simple and therefore efficient decorative panel construction can be achieved.

[0048] The panel may comprise a backing layer attached (e.g. glued) directly or indirectly to the bottom surface of the core layer, wherein the backing layer preferably consists of at least PET. The backing layer may be foamed or unfoamed. The backing layer may contribute to the sound damping properties and / or comfort of the decorative panel. The backing layer preferably comprises PET, more preferably recycled PET. It is conceivable that, like the core layer, the backing layer comprises at least one extended chain polycondensate, preferably at least one extended chain polyester, more preferably at least one extended chain PET, at least partially consisting of polycondensate-based molecules, preferably polyester-based molecules, more preferably PET-based molecules, wherein each molecule comprises at least two polymer chains consisting of recycled polycondensate, preferably recycled polyester, more preferably recycled PET, the polymer chains being chemically bonded to each other via at least one chain extender.

[0049] It is conceivable that the panel comprises complementary coupling profiles at at least one pair of opposite side edges, thereby allowing mutual coupling of adjacent decorative panels. This allows the decorative panel according to the invention to realize, for example, a so-called floating (unglued) floor covering or wall covering. Each side edge of the panel may be provided with a coupling profile. Each coupling profile may comprise one or more tongues and / or one or more grooves. The coupling profile may be substantially formed by the core material (by removing the core material at the side edges).

[0050] The panels may be rectangular panels. The panels may be rectangular or may have alternative polygonal shapes such as triangles, hexagons and parallelograms. The thickness of the core layer may vary but is typically between 4 mm and 10 mm, preferably between 4.5 mm and 8 mm.

[0051] The present invention also relates to a core layer for use in a decorative panel according to the present invention, wherein the core layer comprises chain-extended polyethylene terephthalate (PET) which at least partly consists of molecules based on polyethylene terephthalate (PET), wherein each molecule comprises at least two polymer chains consisting of recycled PET which are chemically bonded to each other via at least one chain extender.

[0052] The invention also relates to a method for producing a decorative panel, in particular a decorative panel according to the invention, comprising the following steps:

[0053] a) mixing a recycled PET material with at least one chain extender, wherein the recycled PET material preferably has an intrinsic viscosity between 0.50 dl / g and 0.80 dl / g, preferably between 0.50 dl / g and 0.60 dl / g, and / or has a molar mass between 10000 g / mol and 20000 g / mol;

[0054] b) feeding the mixture into an extruder, which is preferably a twin-screw extruder;

[0055] c) extruding the mixture through the extruder, preferably at a temperature between 250 and 300 degrees Celsius, more preferably at a temperature between 256 and 285 degrees Celsius, wherein at least a portion of the PET material reacts with at least a portion of the chain extender to produce chain-extended polyethylene terephthalate (PET), wherein at least two polymer chains consisting of recycled PET are chemically bonded to each other via the chain extender, wherein water is optionally produced, and wherein a core layer of the decorative panel is produced;

[0056] d) cooling the extruded core layer, preferably actively cooling it, to a temperature below 100 degrees Celsius;

[0057] e) Applying a decorative top structure over the core layer, thereby forming a decorative panel.

[0058] Preferably, the mass ratio of recycled PET and chain extender mixed during step a) is between 100:1 and 100:2 (50:1). This results in sufficient chain extender to link sufficient PET chains. Preferably, during step a), at least two chain extenders are mixed, wherein the first chain extender is formed from at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA), and the second chain extender is formed from ADR, wherein the mass ratio of the first chain extender to the second chain extender is preferably between 1:1 and 2:1, more preferably 6:4. By applying such a chain extender mixture, preferably in said preferred mass ratio, it is possible to obtain a desired and / or controlled molar mass of the chain-extended PET and thus a desired viscosity of the chain-extended PET (preferably at least 0.8 dl / g) in the reactive extrusion process according to step c). Further advantages and embodiments have been described above and will be described in a comprehensive manner below.

[0059] Further embodiments of the invention will be presented in the following set of non-limiting clauses.

[0060] Terms:

[0061] 1. A decorative panel (1), in particular a decorative floor panel, a decorative ceiling panel or a decorative wall panel, comprising:

[0062] at least one core layer (2);

[0063] a decorative top structure (6) fixed directly or indirectly to the top surface of the core layer (2);

[0064] The at least one core layer (2) comprises a chain-extended polyethylene terephthalate (PET) at least partially composed of molecules based on polyethylene terephthalate (PET), wherein each molecule comprises at least two polymer chains composed of recycled PET, and the polymer chains are chemically bonded to each other via at least one chain extender.

[0065] 2. Decorative panel (1) according to clause 1, wherein at least a portion of the PET-based molecules each comprises at least four polymer chains consisting of recycled PET chemically bonded to each other via at least one chain extender.

[0066] 3. Decorative panel (1) according to clause 2, wherein at least a portion of the PET-based molecules each comprises more than four polymer chains consisting of recycled PET chemically bonded to each other via at least one chain extender.

[0067] 4. A decorative panel (1) according to any of the preceding clauses, wherein the core layer (2) comprises chain-extended polyethylene terephthalate (PET) at least partially composed of PET-based molecules, each of which comprises at least one polymer chain composed of recycled PET and at least one polymer chain composed of virgin PET chemically bonded to each other via at least one chain extender.

[0068] 5. The decorative panel (1) according to any of the preceding clauses, wherein the core layer (2) comprises unbonded recycled PET and / or unbonded virgin PET.

[0069] 6. The decorative panel (1) according to any of the preceding clauses, wherein the core layer (2) comprises unbonded chain extender molecules.

[0070] 7. A decorative panel (1) according to any of the preceding clauses, wherein the core layer (2) comprises chain-extended polyethylene terephthalate (PET) at least partially composed of PET-based molecules, each of which comprises at least two polymer chains composed of recycled PET chemically bonded to each other via at least two different chain extenders.

[0071] 8. The decorative panel (1) according to any of the preceding clauses, wherein at least one chain extender comprises a multifunctional epoxide oligomer.

[0072] 9. The decorative panel (1) according to clause 8, wherein the multifunctional epoxide oligomer (ADR) is represented by the following chemical structure before bonding to the PET chain:

[0073] in:

[0074] R1 to R5 are H, CH 3 , higher alkyl or a combination thereof;

[0075] R6 is alkyl; and

[0076] x, y and z are each between 1 and 20.

[0077] 10. The decorative panel (1) according to any of the preceding clauses, wherein, before bonding to the PET chains, the at least one chain extender comprises at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA).

[0078] 11. A decorative panel (1) according to clauses 9 and 10, wherein the core layer comprises: (i) a mixture of at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA) and (ii) ADR, wherein preferably the mass ratio of the dianhydride to ADR is between 1:1 and 2:1; more preferably, the mass ratio is 6:4.

[0079] 12. Decorative panel (1) according to clause 8 or 9 and clause 10 or 11, wherein at least a portion of the PET-based molecules each comprise:

[0080] a plurality of clusters, wherein each cluster comprises a plurality of polymer chains composed of recycled PET chemically bonded to each other via dianhydrides, preferably PMDA and / or MEDA;

[0081] Wherein, the clusters are chemically bonded to each other through the multifunctional epoxide oligomers.

[0082] 13. A decorative panel (1) according to any of the preceding clauses, wherein the amount of chain-extended polyethylene terephthalate (PET) in the core layer is between 25% and 45%, preferably between 30% and 35% by weight of the core layer.

[0083] 14. The decorative panel (1) according to any of the preceding clauses, wherein the amount of chain extender in the core layer is between 0.25% and 4%, preferably between 0.5% and 1% by weight of the core layer.

[0084] 15. A decorative panel (1) according to any of the preceding clauses, wherein the panel comprises a plurality of laminated core layers, wherein at least one core layer and preferably each core layer comprises PET, more preferably chain-extended PET.

[0085] 16. Decorative panel (1) according to clause 15, wherein the panel comprises three laminated core layers in an ABA configuration, wherein the outer layers (A) have the same composition and the inner layers (B) have a different composition.

[0086] 17. The decorative panel (1) according to any of the preceding clauses, wherein at least one core layer is unfoamed and at least one core layer is foamed.

[0087] 18. The decorative panel (1) according to any of the preceding clauses, wherein the average molar mass of the mutually bonded recycled PET chains is each less than 20000 g / mol, preferably less than 15000 g / mol, more preferably less than 12000 g / mol.

[0088] 19. The decorative panel (1) according to any of the preceding clauses, wherein the core layer comprises at least one inorganic filler, such as limestone, and / or an organic filler, such as wood particles.

[0089] 20. Decorative panel (1) according to clause 19, wherein the amount of filler in the core layer is at least 50% by weight of the core layer, preferably 60 to 70% by weight of the core layer.

[0090] 21. Decorative panel (1) according to clause 19 or 20, wherein the amount of filler in the core layer is at least 1.5 times the amount of PET, preferably chain-extended PET, of the core layer.

[0091] 22. A decorative panel (1) according to any of the preceding clauses, wherein the core layer comprises at least one lubricant, the lubricant being configured to withstand a temperature of at least 200 degrees Celsius, and the lubricant is preferably present in an amount less than 1% by weight of the core layer.

[0092] 23. The decorative panel (1) according to any of the preceding clauses, wherein the core layer comprises at least one lubricant formed by silicone oil, and preferably the amount of lubricant is less than 1% by weight of the core layer.

[0093] 24. The decorative panel (1) according to any of the preceding clauses, wherein the core layer comprises at least one toughening agent, the amount of toughening agent preferably being less than 10% by weight of the core layer, more preferably from 3 to 8% by weight of the core layer.

[0094] 25. The decorative panel (1) according to any of the preceding clauses, wherein the decorative top structure comprises a primer layer applied to the top surface of the core layer and at least one further layer applied to the primer layer.

[0095] 26. A decorative panel (1) according to any of the preceding clauses, wherein the decorative top structure comprises at least one base coating applied directly or indirectly to the top surface of the core layer, and at least one further layer applied to the base coating.

[0096] 27. A decorative panel (1) according to any of the preceding clauses, wherein the decorative top structure comprises at least one decorative layer applied directly or indirectly to the top surface of the core layer, and preferably comprises at least one additional layer applied to the decorative layer, such as a wear-resistant layer and / or a scratch-resistant layer.

[0097] 28. Decorative panel (1) according to clause 27, wherein the decorative layer is a digitally printed decorative layer.

[0098] 29. The decorative panel (1) according to clause 27, wherein the decorative layer is formed by a facing layer or a decorative film.

[0099] 30. The decorative panel (1) according to any of clauses 27 to 29, wherein the top surface of the decorative top structure is provided with a relief pattern, wherein the relief pattern is preferably aligned with the decorative image of the decorative layer.

[0100] 31. The decorative panel (1) according to any of the preceding clauses, wherein the panel comprises a backing layer directly or indirectly attached to the bottom surface of the core layer, wherein the backing layer preferably consists of at least PET.

[0101] 32. A decorative panel (1) according to any of the preceding clauses, wherein the panel comprises complementary coupling profiles at at least one pair of opposing side edges, thereby allowing mutual coupling of adjacent decorative panels.

[0102] 33. A core layer (2) for use in a decorative panel (1) according to any of the preceding clauses, wherein the core layer comprises chain-extended polyethylene terephthalate (PET) at least partially consisting of molecules based on polyethylene terephthalate (PET), wherein each molecule comprises at least two polymer chains consisting of recycled PET chemically bonded to each other by at least one chain extender.

[0103] 34. A method for producing a decorative panel, in particular a decorative panel (1) according to any of the preceding clauses, comprising the following steps:

[0104] a) mixing a recycled PET material with at least one chain extender, wherein the recycled PET material preferably has an intrinsic viscosity between 0.50 dl / g and 0.80 dl / g, preferably between 0.50 dl / g and 0.60 dl / g, and / or has a molar mass between 10000 g / mol and 20000 g / mol;

[0105] b) feeding the mixture into an extruder, which is preferably a twin-screw extruder;

[0106] c) extruding the mixture through the extruder, preferably at a temperature between 255 and 300 degrees Celsius, wherein at least a portion of the PET material reacts with at least a portion of the chain extender to produce chain-extended polyethylene terephthalate (PET), wherein at least two polymer chains consisting of recycled PET are chemically bonded to each other via the chain extender, wherein water is optionally produced, and wherein the core layer of the decorative panel is produced;

[0107] d) cooling the extruded core layer, preferably actively cooling it, to a temperature below 100 degrees Celsius;

[0108] e) Applying a decorative top structure over said core layer, thereby forming said decorative panel.

[0109] 35. The method according to clause 34, wherein the mass ratio of recycled PET and chain extender mixed during step a) is between 100:1 and 100:2.

[0110] 36. The method according to clause 34 or 35, wherein during step a), at least two chain extenders are mixed, wherein the first chain extender is formed from at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA), and the second chain extender is formed from ADR, wherein the mass ratio of the first chain extender to the second chain extender is preferably between 1:1 and 2:1, more preferably 6:4. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] The invention will be explained on the basis of the following non-limiting exemplary embodiments shown in the accompanying drawings. In the drawings:

[0112] Figure 1 Schematically illustrates a decorative panel according to the invention;

[0113] Figure 2 Shows Figure 1 of paneling without the optional intermediate layer;

[0114] Figure 3 and FIG. 4 schematically shows a possible configuration of a complementary coupling profile according to the invention;

[0115] Figure 5 and Figure 6 Other possible coupling profiles according to the invention are schematically shown;

[0116] Figure 7 Schematically illustrates a decorative panel according to the invention;

[0117] Figure 8 shows a possible example of chain extension according to the invention; and

[0118] Fig. 9 Another exemplary embodiment of a chain extension according to the invention is shown. DETAILED DESCRIPTION

[0119] Figure 1A panel (1) according to the invention is schematically shown, the panel having a centrally arranged core layer (2), wherein the core layer (2) comprises a top surface (3) and a bottom surface (4), preferably on opposite sides of the core layer (2). In this non-limiting embodiment, a backing layer (5) is attached to the bottom surface (4) of the core layer. Figure 1 Also shown is a decorative top layer (6) attached to the top surface (3) of the core layer (2). Although in this non-limiting embodiment, the decorative top structure (6) is shown as a single layer, it is conceivable that the decorative top structure (6) includes more than one layer. For example, the decorative top structure (6) can be formed from: a printed decorative layer, such as a digital print layer, a facing layer or a decorative film; an embossed structure or pattern layer that can form a panel relief; and an optional wear layer or protective layer.

[0120] Complementary coupling parts (9, 10) are provided on two opposite sides (7, 8) of the panel (1), which may alternatively be referred to as a pair of opposite edges (7, 8). The first coupling part (7) is in the form of a downward tongue (11) and the second coupling part (9) is in the form of an upward tongue (12). The second coupling part (9) may comprise a single upward tongue (12), at least one upward wing (13) located at a distance from the upward tongue, and a single upward groove (14) formed between the upward tongue and the upward wing, wherein at least a portion of a side (15) of the upward tongue facing the upward wing is inclined and extends in the direction of a normal (N1) to the upper side or top surface (3) of the core layer, and wherein optionally at least a portion of a side (16) of the upward tongue facing away from the upward wing comprises a substantially rigid first locking element (17); and at the second or fourth edge A panel having a single downward tongue (11), at least one downward wing (18) located at a certain distance from the downward tongue, and a single downward groove (19) formed between the downward tongue and the downward wing, wherein at least a part of the side (20) of the downward tongue facing the downward wing is inclined and extends in the direction of the normal (N2) to the lower side or bottom surface (4) of the core layer, and wherein the downward wing optionally includes a second locking element (21), which is preferably substantially rigid, and the second locking element (21) is suitable for cooperating with the first locking element of the third edge of another panel.

[0121] Figure 1It is further shown that the upper side or front side (22) of the upward tongue (12) slopes downwards from the top side (22A) towards the outer side (16). The transition from the inner side (15) of the upward tongue (12) to the top side (22A) forms an alignment edge (23). A similar configuration is present on the other side, wherein the upper side (24) of the groove (19) is inclined. The alignment edge (25) on the downward tongue (11) is arranged on its outer side (26). On both sides, the transition between the tongues (11, 12) and the core layer (2) is formed by bridges, which are an upper bridge (27) on the side of the downward tongue (11) and a lower bridge (28) on the side of the upward tongue (12). The transition (29) from the downward tongue (11) towards its inner side is shown as rounded to facilitate deformation.

[0122] Figure 1 It is further shown that an optional intermediate layer (30) is arranged between the core layer (2) and the decorative top structure (6), and Figure 2 There is no such intermediate layer.

[0123] The core layer (2) comprises chain-extended PET at least partially composed of molecules based on polyethylene terephthalate (PET), wherein each molecule comprises at least two polymer chains composed of recycled PET, said polymer chains being chemically bonded to each other via at least one chain extender. Figure 8 The extended chain is shown in more detail in FIG.

[0124] Figure 2 The layering of the panel (1) is schematically shown, in particular the decorative top structure (6). The decorative top structure (6) comprises an adhesive primer (61), a base coating (62), a transition layer (63), a printed decorative layer (64), a wear layer (65), a structured layer (66) and a scratch-resistant layer (67) arranged on top.

[0125] Figure 3 and FIG. 4 show other possible configurations of complementary coupling parts which may also be used in the present invention as possible embodiments of lateral tongue and groove combinations.

[0126] For example, Figure 3A lateral tongue (32) on a first edge is shown, wherein the lateral tongue (32) extends in a direction substantially parallel to the top surface of the panel, a bottom front region (33) of the lateral tongue is at least partially circular, and a bottom rear region (24) of the tongue is configured as a supporting region, wherein the bottom rear region is closer to the level of the top surface of the panel than the lowest part of the bottom front region; and, on the opposite second edge (8), includes a recess or lateral groove (35) for accommodating at least a portion of the lateral tongue of another panel, wherein the recess is defined by an upper lip (36) and a lower lip (37), the lower lip being provided with an upwardly protruding shoulder (38) for supporting and / or facing the supporting region of the lateral tongue.

[0127] Figures 4a to 4e Various variations of the shape of the lateral tongue and groove are shown which may be used according to the invention.

[0128] Figure 5 and Figure 6 Other possible configurations of complementary coupling parts are shown which may also be used with the present invention as possible embodiments of downward and upward tongue combinations. Figure 5 In the figure, it is shown that Figure 1 and Figure 2 A similar locking system, but with a slightly different shape and with additional locking elements (31) on the outside of the downward tongue (11) and on the upper side of the upward flank (13). Figure 6 In the embodiment of the present invention, the locking element is shown as an open groove, wherein the inner sides (15, 20) of the tongues (11, 12) are inclined, but not towards the core layer, but away from the core layer. The angle of these inner sides (15, 20) is similar to Figure 1 and Figure 2 The angles shown are opposite.

[0129] Figure 7 A panel (1) is schematically shown, with a top surface (3) and a side bottom surface (4) located on opposite sides of a core layer. The decorative panel (1) is a rectangle with four edges. The four edges are opposite edges (7, 8) on the short sides and two opposite edges (7', 8') on the long sides. Figure 7 The AA section shown in FIG. 1 shows the connection portion on the long side, such as Figure 3 4. Along the BB section, the connection part on the short side is shown, as shown in other drawings of the present application.

[0130] Figure 8Chain extension according to the present invention is schematically shown. On the left, PMDA (71) reacted with a PET chain (72) is shown. The PET chain (72) can be, for example, a recycled PET chain. In this process, the ring of PDMA opens and allows up to four PET chains (72) to be connected at the end to obtain a first intermediate product (73). The first intermediate product (73) can also be the final product (73), but better results may be obtained when the intermediate product (73) is used in further chain extension. The intermediate product (73) or its multiplier can then react with an ADR group (74). The free end of the PET chain (72) that is not connected to the end of PMDA (71) and therefore the intermediate product (73) reacts with the ADR group (74) at this time to form an ADB backbone with preferably multiple intermediate products (73) for further chain extension.

[0131] The reaction product of PMDA may be a four-arm star polymer, and the branching reaction with ADR may form a comb-shaped PET with a very short main chain. The main chain is considered to be relatively short because PET (26300 g / mol) is about 9 times the average molar mass of ADR (3000 g / mol). According to the different reaction mechanisms, ADR is more likely to induce branched structures than PMDA, because ADR can achieve branching in just one step, while PMDA requires two steps, especially the secondary esterification or transesterification reaction of PMDA is relatively slow. This can be confirmed by the short reaction time of ADR during batch mixing.

[0132] Fig. 9 It shows that Figure 8 An alternative example of chain extension is shown in FIG. This figure shows that the ADR group (74) reacts with the PET chain (72). In the final product (75), the PET chain (72) has been attached to the ADR group (74). It is also conceivable to form a Figure 8 and Fig. 9 The chain extension combination is shown, where the combination of PET chain (72) and intermediate (73) is attached to the ADR group (74).

[0133] It is obvious that the invention is not limited to the working examples shown and described herein, but that many variations are possible within the scope of the appended claims that are obvious to a person skilled in the art.

[0134] The ordinal numbers used in this document, such as "first", "second", "third" and "fourth", are used for identification purposes only. Therefore, the use of the expression "third connecting profile" does not necessarily require the simultaneous presence of the "first connecting profile". Similarly, the use of the expressions "third locking element" and "second locking element" does not necessarily require the simultaneous presence of the "first locking element". "Horizontal" refers to a direction extending parallel to the plane defined by the tile panel and which direction may intersect the core layer of the tile panel. "Vertical" refers to a direction perpendicular to the plane defined by the tile panel. "Complementary" connecting profiles mean that these connecting profiles of adjacent tile panels can cooperate with each other. However, for this, the complementary connecting profiles do not necessarily have to have a completely complementary form (reverse design). "Proximal" refers to the side closest to the body of the tile panel, while "distal" refers to the side that is farther from the body of the tile panel than the proximal side. The proximal side may face the body of the tile panel, while the distal side may face away from the body of the tile panel.

[0135] In the above, the expression PET can be selectively replaced by at least one other suitable polycondensate, in particular polyester and / or copolymer of PET and / or derivative of PET, such as PETG (polyethylene terephthalate), wherein the PET copolymer comprises, for example, at least one comonomer selected from diethylene glycol (DEG), cyclohexanedimethanol (CHDM), isophthalic acid (IPA), naphthoic acid (NDC) and a mixture of at least two of these comonomers. PETG is a variant of PET, wherein "G" represents ethylene glycol, which is added at the molecular level to provide different chemical properties and is therefore considered a copolymer of PET. Compared with (virgin or recycled) PET, (virgin or recycled) PETG has greater strength and durability, is more impact-resistant, is more suitable for high temperatures, and is therefore a suitable substitute for PET.

[0136] As previously mentioned, in the present invention, recycled PET can be replaced by recycled PETG and / or original PETG, or by a combination of recycled PETG and original PETG. In the present invention, original PET can be replaced by recycled PETG and / or original PETG, or by a combination of recycled PETG and original PETG. The combination of (recycled and / or original) PET and (recycled and / or original) PETG can also be used in at least one panel layer, for example, a core layer. It is conceivable that (recycled and / or original) PET is used in at least one panel layer, and (recycled and / or original) PETG is used in at least one other panel layer. It is conceivable that a plurality of panel layers all comprise PETG, for example, a core layer, at least one wear-resistant layer and / or at least one intermediate layer (intermediate film) between the core layer and at least one wear-resistant layer. The material based on PETG used in at least one panel layer can be foamed or unfoamed (solid). Especially, the core layer based on PETG can be a core layer based on foamed PETG to save weight.

[0137] In order to achieve a foamed PETG (and / or foamed PET) layer, it is advantageous that the layer contains at least one blowing agent, such as an azodicarbonamide (AC) blowing agent (blowing agent), and / or at least one foaming regulator, such as an acrylate (ACR) foaming regulator. For example, such a foaming layer can be prepared from a raw material containing the following components by mass: 100 parts of PET and / or PETG, 1 to 2 parts of a blowing agent (such as an AC blowing agent) and / or 14 to 16 parts of a foaming regulator (such as an ACR foaming regulator). Optionally, at least 100 parts (such as 150 to 350 parts, especially 300 parts) of an inorganic filler, such as limestone and / or talc, can be added to the raw material composition. Optionally, a wax (such as a polyethylene wax) can be added to the raw material composition in a relative amount of, for example, 1 to 3 parts. Optionally, the raw material composition can contain at least one release agent, such as 3 to 7 parts, especially 5 parts of a release agent. Optionally, at least one reinforcing agent is added to the raw material composition, for example in an amount of 5 to 15 parts, in particular 10 parts.

[0138] In the present invention, the foaming regulator preferably acts as a chain extender. The foaming regulator preferably comprises a polymer having (reactive) epoxy and / or ester groups, preferably based on acrylate. The presence of ester groups provides good compatibility to achieve uniform mixing of foaming regulator and PET (and / or PETG). The reaction between the polymer chain of the foaming regulator and PET and / or PETG expands the molecular weight of PET and / or PETG, and significantly improves the melt strength of the mixture. In addition, the foaming regulator based on acrylate has relatively good compatibility for mixing with inorganic fillers. Each epoxy group of the foaming regulator (chain extender) can react with (carboxyl (carboxyl end group)) hydroxyl to form ester. In the case where the foaming regulator molecule comprises multiple epoxy groups, multiple PET (and / or PETG) chains can be combined with the foaming regulator molecule, so these chains can be combined with each other, effectively causing chain extension.

[0139] In the present invention, the amount of blowing agent in the raw material composition is preferably kept limited, for example, 1 part of blowing agent per 100 parts of PET (and / or PETG). This results in sufficient foaming to reduce the layer density (for example, at 0.8 g / cm 3 Up to 1.0g / cm 3 Between and including 0.8g / cm 3 and 1.0g / cm 3 ), thereby reducing the weight of the panel while maintaining sufficient (bending) strength, for example at least 180 MPa, and typically resulting in a relatively high noise reduction coefficient of at least 0.95, which is preferably measured according to the ASTM C423 (-23) standard.

[0140] In the present invention, the inorganic filler is preferably or preferably comprises a mixture of calcium carbonate (limestone) and talc, wherein the mass ratio of calcium carbonate to talc is preferably in the range of (1-9): (9-1), more preferably 1: 1. In the present invention, the inorganic filler may have a particle size of 200 to 400 mesh in some embodiments.

[0141] Because PETG melt is easy to adhere to metal, PETG is easy to adhere to the mold surface during extrusion processing, so this will hinder the smooth flow of PETG, thus will affect the stable production of the panel layer based on PETG. At the same time, due to the adhesion of PETG, decomposition may occur under long-term heating, which will cause the surface of the extruded layer to be relatively (too) rough. For this reason, it is advantageous to add at least one release agent to the mixture (before extrusion). Such a release agent forms a stable lubricating film between the metal mold surface and the melt containing PETG during extrusion, eliminating the risk of adhesion between the mold and the melt mixture. Preferably, the release agent comprises an ester group, which ensures that the release agent is absorbed and fixed to the surface of the PETG chain. In addition, the addition of the release agent ensures the smooth production of the layer based on foamed PETG. The release agent preferably comprises a long-chain alkane skeleton. The release agent is preferably heat-resistant to a temperature of at least 200°C.

[0142] It is envisioned that the at least one chain extender is configured to chemically bond and / or actually chemically bond to at least one (virgin and / or recycled) PET chain and at least one (virgin and / or recycled) PETG chain. It is envisioned that the at least one chain extender is configured to chemically bond and / or actually chemically bond to (i) at least one (virgin and / or recycled) PET chain and / or at least one (virgin and / or recycled) PETG chain, and (ii) at least one other (virgin and / or recycled) polymer chain.

[0143] The verb "to comprise" and its variations as used in this patent publication should be understood to mean not only "to include", but also to mean the phrases "including", "consisting essentially of", "formed of", and variations thereof.

Claims

1. A decorative panel (1), in particular a decorative floor panel, a decorative ceiling panel or a decorative wall panel, comprising: at least one core layer (2); a decorative top structure (6) fixed directly or indirectly to the top surface of the core layer (2); The at least one core layer (2) comprises a chain-extended polyethylene terephthalate (PET) at least partially composed of molecules based on polyethylene terephthalate (PET), wherein each molecule comprises at least two polymer chains composed of recycled PET, and the polymer chains are chemically bonded to each other via at least one chain extender.

2. The decorative panel (1) according to claim 1, wherein At least a portion of the PET-based molecules each comprise at least four polymer chains composed of recycled PET chemically bonded to one another via at least one chain extender.

3. The decorative panel (1) according to any one of the preceding claims, wherein The core layer (2) comprises chain-extended polyethylene terephthalate (PET) at least partially composed of PET-based molecules, wherein each molecule comprises at least one polymer chain composed of recycled PET and at least one polymer chain composed of virgin PET chemically bonded to each other via at least one chain extender.

4. The decorative panel (1) according to any one of the preceding claims, wherein The core layer (2) comprises unbonded recycled PET and / or unbonded virgin PET.

5. The decorative panel (1) according to any one of the preceding claims, wherein The core layer (2) comprises unbonded chain extender molecules.

6. The decorative panel (1) according to any one of the preceding claims, wherein The core layer (2) comprises chain-extended polyethylene terephthalate (PET) at least partially composed of PET-based molecules, wherein each molecule comprises at least two polymer chains composed of recycled PET chemically bonded to each other via at least two different chain extenders.

7. The decorative panel (1) according to any one of the preceding claims, wherein The at least one chain extender comprises a multifunctional epoxide oligomer.

8. The decorative panel (1) according to claim 7, wherein The multifunctional epoxide oligomer (ADR) is represented by the following chemical structure before bonding to the PET chain: in: R1 to R5 are H, CH3, higher alkyl or a combination thereof; R6 is alkyl; and x, y and z are each between 1 and 20.

9. The decorative panel (1) according to any one of the preceding claims, wherein Prior to bonding to the PET chain, the at least one chain extender comprises at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA).

10. Decorative panel (1) according to claims 8 and 9, wherein The core layer comprises: (i) a mixture of at least one dianhydride, preferably pyromellitic dianhydride (PMDA) and / or metamellitic dianhydride (MEDA) and (ii) ADR, wherein preferably, the mass ratio of the dianhydride to ADR is between 1:1 and 2:1; more preferably, the mass ratio is 6:

4.

11. A decorative panel (1) according to claim 7 or 8 and claim 9 or 10, wherein At least a portion of the PET-based molecules each comprise: a plurality of clusters, wherein each cluster comprises a plurality of polymer chains composed of recycled PET chemically bonded to each other via dianhydrides, preferably PMDA and / or MEDA; Wherein, the clusters are chemically bonded to each other through the multifunctional epoxide oligomers.

12. The decorative panel (1) according to any one of the preceding claims, wherein The panel comprises a plurality of laminated core layers, wherein at least one core layer and preferably each core layer comprises PET, more preferably chain-extended PET; wherein the panel comprises three laminated core layers in an ABA configuration, wherein the outer layers (A) have the same composition and the inner layers (B) have a different composition.

13. The decorative panel (1) according to any one of the preceding claims, wherein The mutually bonded recycled PET chains each have an average molar mass of less than 20,000 g / mol, preferably less than 15,000 g / mol, more preferably less than 12,000 g / mol.

14. The decorative panel (1) according to any one of the preceding claims, wherein The core layer comprises at least one inorganic filler, such as limestone, and / or an organic filler, such as wood particles; wherein the amount of filler in the core layer is at least 50% by weight of the core layer, preferably 60% to 70% by weight of the core layer.

15. The decorative panel (1) according to any one of the preceding claims, wherein The core layer comprises at least one lubricant formed of silicone oil and preferably the amount of said lubricant is less than 1% by weight of the core layer.

16. The decorative panel (1) according to any one of the preceding claims, wherein The core layer comprises at least one toughening agent, the amount of which is preferably less than 10% by weight of the core layer, more preferably from 3% to 8% by weight of the core layer.

17. The decorative panel (1) according to any one of the preceding claims, wherein The decorative top structure comprises at least one decorative layer applied directly or indirectly to the top surface of the core layer and preferably comprises at least one further layer applied to the decorative layer, such as a wear-resistant layer and / or an anti-scratch layer.

18. The decorative panel (1) according to any one of the preceding claims, wherein The panels comprise complementary coupling profiles at at least one pair of opposing side edges, thereby allowing mutual coupling of adjacent decorative panels.

19. A core layer (2) for use in a decorative panel (1) according to any one of the preceding claims, wherein The core layer comprises chain-extended polyethylene terephthalate (PET) consisting at least in part of polyethylene terephthalate (PET)-based molecules, wherein each molecule comprises at least two polymer chains consisting of recycled PET chemically bonded to each other by at least one chain extender.

20. A method for producing a decorative panel, in particular a decorative panel (1) according to any one of claims 1 to 18, comprising the following steps: a) mixing a recycled PET material with at least one chain extender, wherein the recycled PET material preferably has an intrinsic viscosity between 0.50 dl / g and 0.80 dl / g, preferably between 0.50 dl / g and 0.60 dl / g, and / or has a molar mass between 10000 g / mol and 20000 g / mol; b) feeding the mixture into an extruder, which is preferably a twin-screw extruder; c) extruding the mixture through the extruder, preferably at a temperature between 255 and 300 degrees Celsius, wherein at least a portion of the PET material reacts with at least a portion of the chain extender to produce chain-extended polyethylene terephthalate (PET), wherein at least two polymer chains consisting of recycled PET are chemically bonded to each other via the chain extender, wherein water is optionally produced, and wherein the core layer of the decorative panel is produced; d) cooling the extruded core layer, preferably actively cooling it, to a temperature below 100 degrees Celsius; e) Applying a decorative top structure over said core layer, thereby forming said decorative panel.

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