TR201810582T4 - Floor panels with reduced weight and material content. - Google Patents

Abstract

The disclosure relates generally to the field of shaping floor panels, for example LVT floor panels. More particularly, the disclosure relates to a method of shaping floor panels and to floor panels produced therefrom.

Description

DESCRIPTION FLOOR PANELS WITH LOWED WEIGHT AND MATERIAL CONTENT technical area Ifsaat is the shaping of floor panels in general, LVT floor panels for example. relates to the field. More specifically, disclosure is a method for shaping floor panels. and the floor panels produced by this method.

Field of Application of the Invention Embodiments of the present invention, in particular, are laminated and mechanically joined by a locking system. decorative material one or more top layers, an intermediate of wood fiber-based material consisting of parquets consisting of the core and a lower balance layer on the back of the core. It is particularly suitable for use on floating floors. Known technique, known systems The following description of the problems and the objects and features of the invention, therefore, is non-restrictive. As an example, this area of application, and especially the long and short sides of mechanical paper or powder-based, formed as rectangular parquet with the purpose of joining It will be intended for laminated floors.

Background of the Invention Conventional laminate intended to be used, for example, for flooring or furniture components the panels are produced through the following steps as shown in Figures 1a - 1d. A decorative paper (2b) and an abrasion-resistant clear coating paper (2a) it is impregnated with thermoset resin and applied to the upper part of an HDF core (3).

A balance sheet impregnated with a melamine resin, commonly referred to as a backing (4) is applied to the rear of an HDF hub. Core with upper (2) and lower (4) layers (3) is moved into a press (5) and the thermoset resins are cured and the layers are deposited. It is pressed under heat and pressure so that it will be connected to the core as shown in 1b. is the temperature.

This method of production and the product produced by such methods are generally the DPL process and DPL products. (Direct Pressure Laminate). Upper and lower surface layers, usually 0.1 - It is 0.2 mm thick.

HDF (High density fibreboard), approx. 6 - 12 mm thick and approx. 800 kg/m3 wood fiber that is heat and pressure cured to be converted into a Contains thermoset resin.

The most common floor size is a 1.3*0.2 meter rectangle with a thickness of about 8mm is the panel. The panels are in a package that takes about 10 panels with a floor area of approximately 2 m2 packaged and supplied. The weight of each package is approximately 16 kg.

Recently, new floor panels with a wood powder-based surface and backing have been developed.

Paper; wood fiber scattered on one side of a core (3), which is usually a sheet of HDF, and a powder backing (4) containing melamine particles and wood sprinkled on the other side of the core fibers, thermoset resins, preferably melamine particles, aluminum oxide particles and color is replaced by a powder-based surface layer (2) containing pigments. Spreader, rollers and with the help of brushes and very delicate layers of about 100 - 800 gr/m2, high on HDF core material, which usually has a thickness of about 7 - 10 mm. can be sprinkled with precision. Surface (2), hub (3) and backrest (4), a paperless and solid surface heat and pressure in a continuous or discontinuous press (5) to obtain a product with a layer and backing pressed under.

The princely powder-based layers can have a thickness of about 0.2 - 1.0 mm. Typical press parameters are similar to conventional laminate flooring, with a pressure of 40 - 80 bar and 10 - It can be a temperature of 160 - 200°C with a pressing time of 40 seconds.

Such wood fiber-based floors, commonly referred to as WFF floors, are thicker and cost-effectively produce a surface with greater impact and abrasion resistance significantly better properties than conventional laminate floors due to the fact that it can be produced they have.

These two production methods can be combined.

A laminate floor with a paper-based surface layer provides better impact resistance and a deeper It may have a powder-based substrate underneath the decorative paper to provide embossing.

The paper backing can be replaced with a dust backing. The substrate is made of resins from the substrate. for impregnation of decorative paper during pressing, where it penetrates the decorative paper can be used.

The WFF floor also has many different layers on the top, for example a high-quality top. layer (2a) and a lower cost substrate (2b) under the top layer can happen. The substrate may contain lower resin content and may contain aluminum oxide. particles are not required.

Paper or powder based surface layers, paper or powder based backing layers and HDF core A common feature for all these materials is wood fibers and preferably thermosetting such as melamine or urea. binders and that they can be cured by heat and pressure. Wood fibers of the same type can happen. When the thermoset resin in the upper and lower layers hardens during pressing, the layers form a first are subject to traction. The HDF core is also heated and soft and easy to bend. is becoming. The backing layer represents the tension generated by the surface layer. stabilizes and the panel is greatly reduced with a small convex backbending when it comes out of the print. is straight. When panels are cooled from approximately 160 - 200 °C to room temperature The second heat shrinkage that occurs is likewise compensated by the backing layer and the panel (1) are mainly flat. A small convex backbend is preferred. Because this in dry conditions in winter, when the relative humidity can drop to 20% or less It prevents the edges from bending upwards.

This pressed plate, which is mostly flat, is caused by the shrinkage of the surface and balance layers. It can contain the tension forces.

The plate is usually equipped with locking systems on the long and short sides as shown in Figure 1c. It is cut into several floor panels and formed. The locking system, in general, with a tongue (10) and a tongue groove (9) for vertical locking and a locking groove (14) for horizontal locking a strip (6) having a cooperating locking member (8).

The surface layer (2) has the same length and width as the backing layer (4) as shown in Figure 1d. has. The locking system can be formed in one piece with the hub. As an alternaive, For example, separate materials may be used to form the tongue (10) and/or the strip (6).

The prices of wood fibers and thermoset resins are increasing, and wood is used for scarcity and energy production. Larger increases are expected in the future due to the possibility of using fiber.

Various methods have been used to protect the material and reduce costs. This kind The methods aim to reveal finer products containing a minimum of resins. More great cost savings, minimal quality related to floor panel and geometry of locking system Meet; only one intermediate core, one surface, all of which are made of thermoplastic material. It relates to floor panels having a layer and a backing layer. Such floor panels are the most It is described in EP2339092 A1 which represents the recent prior art. Weight and material content It would be a great advantage if it were possible to reduce it. Regarding existing laminate and WFF floors problem; these are needed to withstand the heat and pressure arising from the printing process. A high-density material such as HDF, which is essential for stability, impact resistance and strength. they have a belly. Another problem is; panels will allow easy installation. to provide a locking system with sufficient strength and geometry. have a core with high shear strength and a minimum thickness is needed.

Grooves on the back of solid wood floors to increase the flexibility of more panels known to be created. Such panels are easier to attach to the subfloor.

Grooves on the back of the panels, laminate and WFF with mechanical locking systems It is not used on floors. The main reason for this is; of this groove, the balance layer and the locking the stability of the panel and the locking system due to the material being taken from the lower parts of the system will have a negative impact on

Definition of some terms In the text below, the visible surface of the installed parquet is referred to as "front side" or "surface". while the other side of the parquet facing the subfloor is called the "back side".

The starting sheet material used as the base material is called the "core".

The core is a surface layer closest to the front and preferably a balance closest to the rear. When it is covered with a layer of slab, the so-called "plate" and the next step in the general process A semi-finished product that is separated as a 'floor panel' and processed into a plurality of "floor panels" forms.

The upper parts of the two adjacent connection edges of the two parquets joined side by side, however, it defines a "vertical plane" perpendicular to the horizontal plane.

The outer parts of the parquet between the front and the back are called "joint edge". are given. As a rule, the connecting edge; vertical, horizontal, angled, rounded, chamfered etc. It has several "connecting surfaces" that can be movable connecting means. With the "mechanical locking system", the connection It is meant that it can be realized without adhesive. means. By "inward" is meant towards the center of the parquet, and by "outward", means in the opposite direction. using one or more carving tool configurations with a fixed chip removal surface. A method of forming a trough or a ridge until it takes its shape is expressed.

Summary of the invention One purpose of the embodiments of the present invention is to determine the weight and material content of such floor panels. reduce and use such cost saving and material reduction methods as high-quality locking systems and adequate stability during the pressing process and as long as the floor is used. laminated floor containing a thermoplastic material to combine with a core that provides to provide the panels. Another purpose of an aspect of the invention that is not currently claimed is to to provide solid wood floors with reduced weight and material content and increased stability.

A first aspect of the invention; a surface layer on the front, an intermediate core, and on the rear of the core having a backing layer and the core and layers are all made of a thermoplastic material. are floor panels. The panels are a second side of a first side of a first floor panel. a locking system for vertically and horizontally locking the floor panel to an adjacent second edge is equipped with. In a locked position, the tops of the first and second sides are parallel to the surface. They form a vertical plane perpendicular to a horizontal plane. Said locking system is a a tongue and a tongue groove configured to work together for vertical locking, a a downward-open locking provided with a locking element and formed on an adjacent edge a strip with its groove configured to work together for horizontal locking contains. The backing sheet and hub are arranged in several verticals with an opening towards the rear. extending umbilical groove. The area of the backing layer is approximately the area of the surface layer. The backing layer is horizontally and inwardly spaced through a pair of opposing side locking systems. may contain at least three umbilical grooves located.

The area of the backing layer may be less than 80% of the area of the surface layer.

All portions of at least one umbilical groove are enclosed in a vertical plane (VP) on all sides. can be placed.

The panels can be rectangular with long sides and short sides, and the core grooves are may be parallel to the edges.

Core grooves may have a groove depth of at least 0.3 times the floor thickness.

The core grooves may include an opening larger than an interior portion of the grooves.

The backing layer may contain essentially the same fibers as the core.

A second aspect of the invention not claimed here is; each on the front to a surface layer, an intermediate having a core and a backing layer on the back of the core and for the production of floor panels, all of which are made of wood fiber and thermosetting resin. method. The method includes the following steps: - wood fiber forming core grooves on the back of the prefabricated panel creation of filings; o obtaining a mixture by mixing wood chips with thermosetting resin, o sprinkling a mixture of wood chips and thermoset resin on the top and/or bottom of the core, o creation of a sheet by curing the mixture with heat and pressure, o cutting the sheet into several floor panels, and o a strip for horizontal locking on a first and a second panel edge, a locking element and a locking groove and a tongue and a tongue groove for vertical locking the creation of a locking system that includes

The mixture may be sprinkled on the underside of the navel.

The mixture may be sprinkled on the lower and upper parts of the navel.

The hub can be HDF.

Hub grooves on long or short sides before the locking system is created can be created.

With a jigsaw tool that includes hub grooves, several rotary saw blades or a carving tool can be created.

The pressed sheet may be more convex than the floor panel.

The core grooves form a second layer to form the top or bottom layers of the floor panel. It is used to create wood fiber material that can be used in the step. belly button material removed from the core while forming, although the original panel thickness is retained reduces the weight of the panel and reduces the chipping caused by the formation of the core grooves. A panel that is thicker than the original core can be created using Upper and lower layers an entire floor panel containing material originating from the core can be created.

Core and layers, alternatively PVC, PET, preferably reinforced with a filler or a thermoplastic material such as vinyl, and these resulting chips are plastic chips for structuring.

The locking system may alternatively be a protruding strip on the first or second panel edge and a recess from said first or second panel edge to the underside of the other. An upper surface of the protruding strip or a lower surface of the recess, preferably; preferably removable Equipped with an adhesive such as an adhesive tape equipped with a strip.

A third aspect of the invention that has not yet been claimed is a hardwood top and a bottom layer. It is a wood-based floor panel with The bottom layer contains gaps and the top layer contains gaps. forms an upper part.

The panels may have a mechanical locking system on the two opposite sides.

A fourth aspect of the invention not yet claimed; a surface on each front backing layer, a backing layer on a rear side, and an intermediate core intended to produce substantially flat floor panels whose layers are composed of thermosetting resins. is a method, wherein the method includes the following steps: - heat and pressure combined with core, surface layer and backing layers forming a large plate with the correct convex prestress; . splitting the slab into several floor panels; . the rear of the panels so that the convex prestress is at least partially released. creation of hub grooves on the sides.

Core grooves, after the slab has been split into multiple floor panels can be created.

With locking systems, floor panels and production methods suitable for the embodiments of the invention the above-mentioned objectives can be achieved in whole or in part.

Brief Description of Figures The present invention is further elaborated, for example, with reference to the accompanying schematic drawings illustrating their embodiments. will be explained in detail.

Figures 1a - d show the prior art.

Figures 2a - d show a floor panel according to one embodiment of the invention.

Figures 3a - e show alternative embodiments of the invention.

Figures 4a - d illustrate the construction of a floor panel according to one embodiment of the invention. shows.

Figures 5a - e show the configurations of the umbilical grooves.

Figures Sa - e show the core grooves on a solid wood floor according to embodiments of the invention and shows the stabilization of a panel with core grooves.

Figures 7a - C show configurations of tools for forming hub grooves.

Figures 8a - 0 of cost-effective locking systems that can be combined with hub grooves. shows their configuration.

Description of Embodiments of the Invention A first construction of parquets equipped with an inventive mechanical locking system, Figures 2a - Shown in 2d. The floor panel has a locking on the long (1 a, 1b) and short (1 0, 1d) sides. includes the system. Figure 2a shows the front with the surface layer (2) and Figure 2b shows the backrest layer (4) reveals the back side. The area (A') of the surface layer is mainly the backing The area of the layer (4) is the same as (A). Figure 20; a wood such as HDF, chipboard or plywood in the backing layer (4) on the back side towards the core (3), which can be a base plate essentially vertical core grooves with an opening facing the rear of the buildable panel (19a, 19b). The hub can also be made of plastic material. This kind shaping can be done with rotary saw blades (20a) as shown in Figure 2d.

Carving can also be used. The panels are usually with a downward facing surface layer (2). they are processed. Jigsaw blade; from top to panel (20a) or through the surface layer (2) facing up, down towards the panel (20a) and into the panel rotary saw blades it is moved away from the panel (200) when it is displaced relative to it. This is preferred placed inward from the sides and preferably from the vertical plane (VP) in the configuration, and so that it will not interfere with any part of the locking systems on the long and short sides Several umbilical grooves (19a, 19b) are formed in the figure. Grooves (19) can also be fixed or jigsaw can be formed with non-rotary engraving tools.

Creation of grooves; which can be mixed with thermosetting resin according to the embodiments according to the invention and wood powder that can be sprinkled on a core to form the surface and/or backing layer. wood chips (21) which can be ground and sieved to transform brings. The core grooves are mainly used to protect the material, the upper (2) or the lower (4). It is used to provide wood fiber material that can be used in layers. of the floor panel They can also be used to reduce weight.

Figures Sa - 3e show that the hub grooves (19) can be created with many different geometries and patterns. shows. The umbilical grooves (19) have different widths as shown in Figure 3b. can happen. The groove length may be smaller than the length of the backing layer (BL).

They can be discontinuous, as shown in Figures 30 and 3d, and have a gradation as shown in Figure 3e. They can extend from one edge to the other. The grooves are mainly the outer layer of the backing layer. It can be placed in parts of it and can be a middle area (MA) without any grooves.

This is to increase the stability of the panel and to remove the backing layer when parts are separated from the backing layer. can be used to reduce the negative impact on Grooves, long sides and/or short can be created by the parties. Panels can also be square.

The core grooves reduce the area of the backing layer (A). The area of the backing layer (A), approximately 60% to 85% of the area of the surface layer (A') in the embodiments shown. This, This means that the balance layer will lose 40-15% of its strength. A thicker back layer or increased resin content compensates for the narrowed backing area of this type.

The starting area after pressing and the backing area (A) compared to the area of the surface layer (A') Figures 4a - 4d illustrate the construction of a floor panel (1) according to embodiments of the invention. shows. A wood powder based substrate (2b) is applied over a core (3). Shape 4b; a surface comprising a wood powder topsheet (2a) or a decorative paper and coating It can show that the layer (2) can be applied on the substrate (2b). A dust back layer (4) can be applied on the back side of the core (3). Figure 40 sawdust (21) occur shows the creation of an umbilical groove (19) This type of sawdust; can be ground, sieved and can be mixed with thermoset binders. This material is in Figure 4b. to create a wood-based top layer and/or bottom layer and/or backing layer as seen It can be sprinkled on the belly. Finally, the locking system as seen in Figure 4d (10, 9, 6, 8, 14) are created.

Milling or carving of core grooves, after pressing and single large before cutting into panels, after cutting only after forming the locking system before, after the locking system has been formed on the two opposite sides, or after the locking It can be created as a final operation after the creation of the system. This type of production steps can be combined and some troughs can be formed in various production steps.

The core grooves provide sufficient wood fiber material for the various layers described above. can. Cured thermosetting resins consisting of sawdust, mixed with wood dust It is compatible with melamine powder and no separation of fibers and cured resins is required. Backrest and the surface may contain new pure thermoset resins and already cured resins.

Figures 53 - e; a vertically extending groove at a ratio of, for example, 0.1 - 0.5 times the floor thickness (T) depth (GD) includes a groove width (GW) of approximately 0.5 - 1 times the floor thickness (T). shows the different preferred geometries of the hub grooves that can horizontal between the core grooves at a rate of approximately 0.2 - 1 times the floor thickness (T) as shown. an interval (S) extending as

The core grooves can have different shapes and the inner core grooves 19b improve the stability of the panel. They can be formed with a smaller groove depth (SE) than the outer grooves (1%) to increase

The hub grooves 190 are, for example, with an undercut by a carving tool (20). can be created. For example, core grooves with a groove depth (SE) of 0.8 times the panel thickness (T), wall whose impact resistance requirements are much lower than those for floor panels can be created on the panels.

Figures 50 - 5e show the hub grooves 19 seen from the long sides. panels. short bendable with a flexible tongue (10) that allows locking by vertical folding at the edges (10, 1d) Includes a locking system. Figure 50, between locking systems on opposite short sides a hub groove (19) with a groove length (GL) smaller than the distance found shows. Figure 5d shows that the hub groove (10) is curved at one short edge (1d) and the locking that it is parallel to the surface on the other edge (10), intersecting part of its groove (14). shows. Such configurations only begin when the formation of the hub grooves 19 begins. or when finishing allows the jigsaw tool to be moved during shaping. Shape 5e is a hub formed with a fixed tool and intersecting the locking strip (6) and the locking groove (14). (19) shows the case.

To create core grooves, eg 0.5 mm backing layer and 0.5 mm substrate can provide sufficient material. The backing layer and preferably the most of the surface layers. at least some parts of it were created using material obtained from the core, with an 8 mm a 7 mm HDF core can be used to produce the floor panel. This saves material and can result in a weight reduction of approximately 15%.

Core grooves, a groove worth 50% of the floor surface and 40% of the floor thickness (T) When formed in such a way as to reduce the backing layer with depth (SE) material savings and a weight reduction of approximately 20% can be achieved.

Core grooves, preferably cheaper than wood and/or greater reduction of sound for example It can be filled with material that gives other features to the floor, such as

Chips can of course also be used to generate thermal energy wholly or partially.

Embodiments of the invention therefore include a wood-based core and the weight of the core grooves. reduction and where sawdust is used for energy or as a filler in various applications It can also be used on floors.

Shaping the navel grooves after the printing process; pressing of the backing layer and During cooling, it acts against the shrinkage of the upper layer and the pressed sheet from the core grooves formed in the floor panel after pressing. provides the advantage of being unaffected.

However, the formation of the core grooves part of the balance layer. away, and this will allow tension to be released and the grooves of the panel edges It can cause it to bend upwards after it is formed. Such a panel it will not be completely straight and may be slightly concave along its length and width.

Figures 6a - 60; Caused by the formation of umbilical grooves as shown in Figure 6a large Ievhanin with a backward bias adapted to dimensional changes that such problems can be countered and completely eliminated if they are created. indicates that it can be removed. Prestressing, for example, may contain more resin and with a thicker backing layer that can be cured at a higher temperature than can be realized. Such a production method; when pressed and cooled, Ievhanin, a larger rearward than the final floor panel with hub grooves on the rear characterized by its bending. immediately before pressing while the sheet is still hot. to obtain a plastic deformation even after a mechanical bending and the surface It can be used to stretch the layer. In this way, "over-bending" occurs backwards and partially back to a largely straight position when the bellybuttons (19) are formed is spreading. Figure Gb shows that some of the tension is released when the hub grooves are formed. the floor panel by forming the grooves and edges as shown in Figure 6c. shows that it is mostly flat.

Figure 60 shows that the core grooves are e.g. paper, plastic foil, foam, cork or a piece of wood. It shows that it can be coated with a separate coating layer (23) such as a coating. This; grooves It can be used to hide, provide moisture tightness or reduce sound. find it core grooves suitable for their configuration, therefore, an upper and lower wood veneer plywood, It can also be used on coated floors where it is bonded to a wood-based core such as HDF or chipboard. can be used.

Figure 6d; the core grooves (19) forming method, on solid wood bodies (3) the core grooves (19) preferably solid wood in which the panel is formed along the fibers (24) in the longitudinal direction It shows that it can also be used on floors. Closing the opening (25) of the navel grooves (19) a wood veneer or a wood veneer as a veneer layer (23) for can be used. For example, such wood, which may have a thickness of 0.5 - 1.0 mm or more The base coating layer (23) can also provide stability and prevent bending and twisting. can prevent. A tension is produced when the moisture content of the polish shrinks the veneer or wood layer. It can be adapted to the moisture content of the solid wood body.

Figure Se illustrates a wood-based floor panel with a solid wood top (2) and an underside (4) layer. shows. The sheet can be manufactured from different types of wood glued together. Lower layer (4) includes spaces (26). The top layer covers the upper part (27) of such voids. can create. Gaps can also be created in the upper layer and the lower layer may form a sub-part of the voids.

Different types of wood glued together can have approximately the same thickness.

The locking system can be formed partially or completely in the substrate (4). In the substrate (4) Hub grooves (19) with a downward facing opening can be formed. in figure oe the configuration shown is solid, which can be shaped and glued in the same way as described above. It may contain HDF sheets instead of wooden sheets. This type of joint hub is a traditional It can be laminated as solid HDF board. This method gives a thickness of about 8 - 12 mm. It is particularly suitable to be used for thicker laminated panels with

Core grooves or gaps made of solid wood allow the weight of the solid wood floor It provides advantages that can be reduced and increased stability can be obtained.

Sawdust from core grooves or cavities can be used for thermal energy or as particle boards. It can be used for the production of other powder-based floors or fiber-based boards.

Mixing wood chips with a binder and a core that can be machined as a separate layer It is also possible to produce an artificial wood veneer that is glued against the opening of the grooves.

The same technology is used with a plywood-based core and a coated surface layer. can be used on the ground.

Figure 7a is a diagram containing several rotary saw blades that can be used to form the hub grooves (19). shows the tool (20).

Figure 7b shows an engraving tool (20) with several horizontally offset engraving teeth (20a-d). shows. The engraving tool is preferably fixed in the horizontal direction and the panel is held against the tool. it is moved towards the engraving tool in the feed direction (FD). Each disc is made of HDF material It can engrave a section of about 0.3 - 0.5 mm. The groove may be V or U shaped or even larger than the opening, having an interior with a horizontal extension perpendicular to the length of the groove available in the form of an undercut.

Figures 8a - 8c, locking adapted to separate from the large Plate with overlapping edges (OL) further with a non-linear cut made with carving systems and preferably with engraving tools (20a, 20b). demonstrates that substantial cost savings can be achieved. Figure 8a shows a protruding tongue (10) and illustrates a locking system comprising a strip (6) protruding on the same edge. This kind of connection geometry, which is revealed when panels are cut and locking systems are created. It can be used to ensure that material waste (W) is significantly reduced. Figure 8c; so that the rear side (Sa) of the strip (6) is sloping upwards and that one outer portion of the strip, one shows that it can be formed in such a way that it is closer to the surface than the interior. All this kind forming and material waste, wood that can be used in the top or bottom layers of a panel can be used to supply the fibers.

umbilical grooves; can be placed in the same horizontal plane (HP) with overlapping edges non-linear separation, which makes it possible to divide into several panels with such a geometry, and Can be combined with locking systems.

The entire floor panel is made of wood material obtained from the core of the other floor panels. possible to create. Only melamine powder needs to be added to the mix. Top layer, as a higher density can be created during pressing of the powder mixture. It may be harder than the navel. Such panels can be formed with embossed structures and can be factory painted, varnished or digitally printed, or removed from installation. It can then be painted and/or polished.

Claims (1)

REQUIREMENTS Floor panels (1, 1'), each comprising a surface layer (2) on one front side, a backing layer (4) and intermediate core (3) on the other side, the intermediate core, surface layer and backing layer all made of thermoplastic material. wherein said floor panels are provided with a locking system for vertically and horizontally locking a first edge of a first floor panel (1) to an adjacent second edge of a second floor panel (1), wherein, when in a locked position the tops of the first and second sides form a vertical plane (VP) perpendicular to a horizontal plane (HP) parallel to the surface layer (2), said locking system being a tongue (10) and a tongue (10) configured to work together for vertical locking. The groove (9) and a downwardly open locking groove (14) on the first edge, provided with a locking element (8) and formed on the second edge, are to work together for horizontal locking. e includes a structured strip (6), floor panels (1, 1'); The backing layer (4) and the intermediate core (3) comprise at least two vertically extending core grooves (19) with an opening towards the rear, and the area of the backing layer (A) is greater than approximately 90% of the area (A') of the surface layer. characterized by low It is the floor panels according to claim 1 and its feature is; the backing layer (4) comprises at least three core grooves (19) spaced horizontally and inwardly from a pair of opposing side locking systems. It is floor panels according to claim 1 or 2, and its feature is; the area (A) of the backing layer is less than 80% of the area (A') of the surface layer. It is floor panels according to any of the claims 1-3, and its feature is; all portions of at least one umbilical groove (19) are arranged in the vertical plane (VP) on all sides. It is floor panels according to any of the preceding claims, and its feature is; the floor panels are rectangular with long sides (1a, 1b) and short sides (10, 1d) and the core grooves (19) are substantially parallel to the long sides. It is floor panels according to any of the preceding claims, and its feature is; the core groove depth (SE) is at least 0.3 times the floor thickness (T). It is floor panels according to any of the preceding claims, and its feature is; The floor panels according to any one of the preceding claims, characterized in that the core grooves (19) have a groove width (GW) greater than an interior part of said groove; thermoplastic material is PVC, PET or vinyl. It is floor panels according to any of the preceding claims, and its feature is; the intermediate core, the surface layer and the backing layer contain a filler. It is floor panels according to any of the preceding claims, and its feature is; the floor panels comprise a bendable locking system with a flexible tongue (10) that allows locking with vertical folding at the short edges (10, 1d). It is floor panels according to any of the preceding claims, and its feature is; hub grooves (19) have a groove length (GL) smaller than the distance between the locking systems on opposite short sides. It is floor panels according to any of the preceding claims, and its feature is; the intersection of the hub grooves (19) with the strip (6) and the locking groove (14). It is floor panels according to any of the preceding claims, and its feature is; the core grooves (19) extend from one edge of the floor panels to the other. It is floor panels according to any of the preceding claims, and its feature is; is that a trough length is smaller than a length (BL) of the backing layer. It is floor panels according to any of the preceding claims, and its feature is; umbilical grooves (19) are discontinuous.