Patent Description:
More particularly, the present invention relates to a method for manufacturing floor panels, wherein the floor panels comprise a carrier on the basis of thermoplastic material and a top layer provided on the carrier. It is noted that by the term "thermoplastic material", a material has to be understood which comprises at least a thermoplastic synthetic material. Apart from the thermoplastic synthetic material, the thermoplastic material may also comprise fillers, such as chalk or lime, and/or additives, such as plasticizers, impact modifiers and stabilizers. It is also noted that by "a carrier on the basis of thermoplastic material" a carrier has to be understood which indeed comprises thermoplastic material, however, which does not have to consist thereof entirely or substantially. Floor panels with a carrier on the basis of thermoplastic material have the advantage that they can be made waterproof. It is also noted that by the term "carrier", the portion of the floor panels is indicated except the top layer. Thus, the carrier has a supporting function for the top layer provided thereon. The top layer which is applied on top of the carrier preferably is of a decorative nature.

Still more particularly, the invention relates to a method as described herein above, wherein the floor panels are suitable for being applied in a so-called floating floor covering. For forming such floating floor covering, the floor panels can be provided with mechanical coupling means or coupling parts on one or more of their edges. These coupling means allow coupling the floor panels to each other, and preferably they effect a horizontal as well as a vertical locking among the coupled floor panels. The coupling parts preferably are at least partially manufactured from the material of the carrier, and they may or may not make use of a separate locking element or an insert, as described as such in, amongst others, the documents <CIT>, <CIT> and <CIT>.

From the state of the art, various methods such as described herein above are known, wherein below a non-exhaustive list of such known methods will be given.

Documents <CIT> and <CIT> describe the application of an extrusion process for forming the thermoplastic carrier described therein. Such extrusion process, however, mostly is slow. Moreover, extruded boards or panels tend to warp. Apart therefrom, when extruding rigid thermoplastic material, there is a risk of degradation of the material. Such rigid material indeed mostly is characterized by a high melt viscosity, which during extruding may lead to a disadvantageously high friction heat. The presence of fillers, such as chalk or lime, does not help here, in view of the fact that they will further increase the melt viscosity of the thermoplastic material. The extrusion process also offers only limited possibilities for varying the composition of the carrier material across the thickness thereof. A possibility is providing empty chambers in the carrier, such as described in US '<NUM>. Although this may lead to a certain weight reduction, the thermoplastic carrier still remains quite expensive. WO '<NUM> further describes the foaming of the thermoplastic carrier. This may result in a certain weight reduction.

From document <CIT>, a floor product is known which comprises two synthetic material-based semi-finished products laminated together, namely a first and a second semi-finished product. For forming the second semi-finished product, calendering and laminating techniques are applied. However, such calendering techniques mostly are expensive. Moreover, the calendering process results in floor panels with very high density. Apart therefrom, with rigid thermoplastic material, the speed of the calendering process is limited due to the mostly high melt viscosity of such material.

Document <CIT> discloses the strewing of thermoplastic granulates, after which said strewn granulates are consolidated between the belts of a continuous press device. More specifically, according to WO `<NUM> successively two layers of granulate are strewn, wherein a reinforcement layer is enclosed between these two layers. Such strewing process allows a smooth production. Such process also offers the possibility of variation in the composition of the substrate. For example, various granulates can be strewn in the successive layers. The strewing technique, such as described in WO `<NUM>, however also results in floor panels with high density.

<CIT> which is regarded as the closest prior art, upon which the preamble of claim <NUM> has been based, discloses a method for manufacturing floor panels, comprising at least the step of strewing wood plastic composite material and consolidating the strewn material. The wood plastic composite material may comprise a polymer having a polyolefin group. The top layer of the floor panels of US'<NUM> may comprise a polymer sheet, for example of a sheet of polypropylene, in the top layer.

The present invention relates in particular to a method for manufacturing floor panels, wherein the floor panels comprise a carrier on the basis of thermoplastic material and a top layer provided on the carrier; and wherein the method comprises at least the steps of strewing the thermoplastic material, for example, on an underlying transport conveyor, and consolidating the strewn thermoplastic material.

Such method is known as such from the already herein above-mentioned documents WO '<NUM> and US '<NUM>, as well as, amongst others, from the documents <CIT>, <CIT>, which is related to WO '<NUM>, <CIT> and <CIT>.

WO '<NUM> describes a method for manufacturing laminated floor panels with a core of Wood Plastic Composite or WPC. The method comprises, amongst others, the strewing of WPC material on an underlying transport belt, after which the strewn WPC material, under the influence of pressure and temperature, is treated further and is consolidated. The WPC material is strewn in the form of granulates.

From WO '<NUM>, a method is known for manufacturing a carrier for decorative floor panels. The method comprises the strewing of a granulated thermoplastic basic material. Apart from the thermoplastic, the basic material also comprises a filler and a pore-forming agent. As an example of a pore-forming agent, an expandable microsphere is mentioned. The strewn basic material is consolidated. To this aim, as described, a double-belt press can be applied.

WO '<NUM> discloses a method for manufacturing floor panels, which comprises the step of strewing a thermoplastic material in the form of a granulate. Thereafter, the strewn material is processed and consolidated by means of a press device.

In each of the herein above-mentioned documents WO '<NUM>. WO '<NUM>, WO '<NUM>, WO '<NUM> and WO '<NUM>, the thermoplastic material described therein is strewn as a granulate. Such granulate is obtained by granulating an extrudate on the basis of a heated or molten dry-blend. By a dry-blend, as known as such from the state of the art, a dry, freely flowing powder has to be understood, which apart from the synthetic material also comprises additives, such as plasticizers and stabilizers, and/or fillers, such as chalk or lime. For forming the dry-blend, the synthetic material is mixed with the additives and/or the fillers, wherein the applied temperature will remain below the glass transition temperature (Tg) of the synthetic material.

When manufacturing a carrier on the basis of strewn and consolidated synthetic material granulate, obtaining a homogeneous carrier is difficult. In fact, the original synthetic material granulates rarely are completely molten again during consolidating. Moreover, the dimension of the granulate limits the minimally obtainable layer thickness. WO '<NUM> provides the strewing of so-called micro-granulate, whereby the limit of the minimally obtainable layer thickness is lowered further. Preparing micro-granulate, however, requires special techniques. Moreover, the granulating process can alter the features of a component of the dry-blend such that the function of the component will be lost entirely or partially. Such loss of function may be, for example, the consequence of a heating of the dry-blend up into the region of or above the glass transition temperature of the respective synthetic material.

The present invention primarily aims at an alternative method for manufacturing floor panels, wherein according to various preferred embodiments solutions are offered for problems with the methods of the state of the art.

To this aim, the present invention is defined in claim <NUM>. According to a first special preferred embodiment, the invention relates to a method for manufacturing floor panels, wherein the floor panels comprise a carrier on the basis of thermoplastic material and a top layer provided on the carrier; and wherein the method comprises at least the steps of strewing the thermoplastic material and consolidating the strewn thermoplastic material; with the characteristic that the thermoplastic material is strewn as a dry-blend.

Thus, the thermoplastic material is not strewn as a granulate, but as a dry-blend. Thus, in other words, it has not undergone a granulating process prior to the actual strewing. That the thermoplastic material is strewn as a dry-blend and the granulating process thus does not have to be performed, may entrain various advantages. On the one hand, a more ecological production of floor panels can be provided. The energy consumed during the granulating process thus can be economized. On the other hand, a more economical production of floor panels is allowed. Namely, a process step, namely the granulating step, can be omitted. Apart therefrom, the features of the individual components or elements of the dry-blend, such as, for example, the synthetic material, additives and/or fillers, can be guaranteed better. Also, a more homogeneous composition of the consolidated layer can be obtained. Further, by means of dry-blends very thin layers can be strewn, for example, layers having a thickness of <NUM> millimeter or less.

The dry-blend can be composed similarly to a dry-blend which is on the basis of a granulate to be formed, such as a dry-blend which is on the basis of an extrudate such as described herein above. The dry-blend may comprise, for example, a thermoplastic synthetic material with a (Fikentscher) K-value which is smaller than or equal to <NUM>. For example, polyvinyl chloride (PVC) can be applied having a (Fikentscher) K-value which is smaller than or equal to <NUM>.

Preferably, the composition of the dry-blend in fact is different from the composition of a dry-blend which is on the basis of a granulate to be formed. For forming the granulate, the last-mentioned dry-blend also is subjected to a shear treatment, for example, during the forming of the extrudate. Such shear treatment contributes to a good flow and fusion of the components of the dry-blend. In view of the fact that the dry-blend to be strewn is not processed to a granulate, such shear treatment in that case is absent. Surprisingly, it has shown that in that case still a good mixing of the components of the dry-blend can be obtained. To this end, the thermoplastic material preferably shows one or more of the following characteristics:.

Most preferably, the thermoplastic material shows all of the herein above-mentioned characteristics. Such thermoplastic material shows a particularly good mixture between the components of the dry-blend, even in the absence of a shear treatment as described herein above.

It is also noted that the invention does not exclude that the thermoplastic material, instead of PVC, comprises another thermoplastic synthetic material, such as, for example, polyethylene, polypropylene or polyurethane, or such as, for example, a thermoplastic polyester, such as polyethylene terephthalate (PET). The thermoplastic material may also comprise a combination of two or more of the herein above-mentioned thermoplastic synthetic materials.

The thermoplastic material preferably relates to a so-called rigid thermoplastic material, which has the advantage that the risk of telegraphing of possible imperfections on an underlying surface across the floor panels can be minimized. Herein, it is advantageous that a strewing process is applied, in view of the fact that rigid material can be processed smoothly by means of a strewing process and in particular can be processed smoother than by means of an extrusion or calendering process.

Preferably, the thermoplastic material comprises a filler. The filler can be an organic filler. Example of organic fillers are wood-based fillers, such as wood particles, which wood particles in particular can relate to wood flour, wood fibers and/or wood chips. According to an alternative, the filler can be an inorganic filler, such as chalk or lime. According to still another alternative, the thermoplastic material can comprise an organic as well as an inorganic filler.

The thermoplastic material can comprise an impact modifier, preferably in an amount of <NUM> to <NUM> phr, a stabilizer, such as a Ca/Zn stabilizer, preferably in an amount of <NUM> to <NUM> phr, and/or a color pigment, such as carbon black. In the case of a color pigment, the color pigment preferably is added in liquid form to the thermoplastic material. The inventor in fact has found that color pigments in liquid form can be smoothly blended into a dry-blend.

In particular, the thermoplastic material can comprise separate glass fibers, as described as such in WO '<NUM>.

It is also noted that the invention does not exclude that the carrier relates to a multi-layered carrier. In the case of a multi-layered carrier, at least one layer of the carrier is realized on the basis of the thermoplastic material, as described herein above, herein below called the layer strewn as a dry-blend. The one or more remaining layers can also be made on the basis of thermoplastic material and can be formed in any manner. So, a remaining layer can be formed by means of strewing, extrusion, calendering and/or coating techniques. If a strewing process is applied for forming a remaining layer, the material of this remaining layer can be strewn in any form, for example, as a dry-blend or as a granulate. According to another example, one or more of the remaining layers can be extruded online or offline with the strewing process of the layer strewn as a dry-blend. In any case, the one or more remaining layers are adhered to the layer strewn as a dry-blend preferably by means of a thermal lamination process, for example, in that the layer strewn as a dry-blend is consolidated together with or in the presence of the material of the one or more remaining layers, or in that the consolidated layer strewn as a dry-blend is thermally laminated to the one or more remaining layers, or in that the one or more remaining layers are formed on the consolidated layer strewn as a dry-blend.

In accordance with the invention, the method according to the first special preferred embodiment also comprises the step of foaming the thermoplastic material, and the thermoplastic material to this end is provided with a chemical blowing agent. This preferred embodiment of the method according to the first special preferred embodiment offers the advantage that a particularly good foaming of the carrier can be obtained. The inventor in fact has found that, as the thermoplastic material is strewn as a dry-blend, the features of the blowing agent incorporated into the dry-blend can be guaranteed such that a very good foaming of the thermoplastic material is obtained. Consequently, the method according to the first special preferred embodiment allows reducing the density of the carrier, such that an economization of raw materials and energy can be realized, as well as new features can be effected, such as comfort and dimensional stability.

The step of foaming the thermoplastic material is performed after the step of strewing the thermoplastic material; however, foaming does not have to take place immediately after strewing. In accordance with the invention, the step of foaming is performed during the step of consolidating the strewn thermoplastic material. The inventor in fact has found that the conditions during consolidating are excellently suitable for performing the foaming process. That the thermoplastic material is foamed during the consolidation process, further offers the possibility of an energy-efficient foaming. The foaming and consolidating process in fact can be performed in one and the same device, for example, a preferably heated press device. Moreover, such press device can calibrate the obtained thickness of the foamed layer.

The blowing agent is a chemical blowing agent, for example, azoisobutyronitrile or azodicarbonamide. Although the use of a chemical blowing agent for foaming polymer materials is known as such, for example, in an extrusion or injection molding process, the inventor has found that such chemical blowing agent also provides for an excellent foaming when it is integrated into a dry-blend to be strewn. Apart therefrom, it is apparent that such chemical blowing agent behaves excellently in conditions which are typical for the consolidating process subsequent to strewing.

According to a variant not pertaining to the claimed invention, the blowing agent relates to an expandable microsphere. The use of such microsphere as a blowing agent is known as such from, amongst others, the documents <CIT> and WO '<NUM>. However, the inventor has found that embedding such microsphere in a dry-blend to be strewn can be extremely advantageous. The dry-blend to be strewn in fact provides for that the features of the microsphere can be guaranteed such that a very good foaming of the thermoplastic material is effected. The risk of degradation of the expandable microsphere, for example, as a result of a granulating process, can be minimized, for example. Such microsphere comprises a preferably thermoplastic covering which encloses a gas, more particularly butane or pentane. When they are heated, for example, during the consolidation process, due to the gas the internal pressure will rise and at the same time the covering becomes softer, resulting in a significant expansion of the microspheres.

According to another preferred embodiment of the method according to the first special preferred embodiment, the thermoplastic material comprises a density-reducing filler, such as perlite, vermiculite and/or silicate. Here, this relates in particular to an expanded, foamed, porous or hollow filler. In the case of an expanded filler, here a filler is intended which is already expanded prior to being added to the dry-blend. In particular, the expanded filler relates to an already expanded microsphere.

According to an alternative not pertaining to the present invention as claimed, the blowing agent relates to a physical blowing agent.

Preferably, when applying a blowing agent, or with foaming in general, at least a weight reduction of <NUM>%, more preferably at least a weight reduction of <NUM>%, and still more preferably at least a weight reduction of <NUM>% is obtained, wherein it even has proven possible to achieve a weight reduction of at least <NUM>%.

The step of consolidating of the strewn thermoplastic material preferably is performed under the influence of pressure and/or temperature. To this aim, a preferably heated press device can be applied. The press device relates in particular to a belt press, such a, for example, a double-belt press. The press device may relate to an isobaric press.

The method according to the first special preferred embodiment preferably also comprises the step of providing the carrier with a reinforcement layer, more particularly a glass fiber cloth or glass fleece. The reinforcement layer can increase the dimensional stability of the floor panels, which is desirable with floor panels on the basis of a thermoplastic material. Such floor panels in fact may be subject to considerable shrinkage or expansion. Apart therefrom, it is noted that the method offers a smooth possibility for enclosing or embedding a reinforcement layer into a carrier on the basis of foamed thermoplastic material.

Preferably, the step of providing the reinforcement layer takes place prior to the step of consolidating the thermoplastic material. A good embedding of the reinforcement layer then can be effected in the consolidating process. However, it is not excluded that, in the case that the reinforcement layer is provided on the thermoplastic material, this thermoplastic material already has been compressed or pressed.

According to a particular embodiment, the reinforcement layer is provided such that, during consolidating by means of a press device, it is directly supported by a press element, such as a press platen or a pressing belt. This manner of providing the reinforcement layer is described as such in the document with the application number <CIT> and can minimize the risk of deforming the reinforcement layer or of damaging the reinforcement layer during the press treatment.

According to an alternative embodiment, the reinforcement layer, in the case of a multi-layered carrier, is provided between two layers prior to consolidation of these layers, as described as such in WO '<NUM>. Preferably, the reinforcement layer thus is provided between two layers which are strewn and/or foamed. In such case preferably at least one, and still better both, of these layers are strewn as a dry-blend. Strewing as a dry-blend provides for good embedding of the reinforcement layer, whereas still a high weight reduction by means of foaming can be achieved.

In particular, a plastisol can be provided on the aforementioned reinforcement layer, as described as such in <CIT> (published as <CIT>). So, an excellent adherence of the reinforcement layer in the carrier can be effected. The plastisol preferably relates to a suspension of PVC particles in liquid plasticizer.

It is also noted that the present invention does not exclude that the carrier is provided with a plurality of reinforcement layers, in particularly a plurality of glass fiber cloths or glass fleeces.

The carrier preferably has a thickness of at least <NUM> millimeters, more preferably a thickness of at least <NUM> millimeters, and still more preferably a thickness of at least <NUM> millimeters. Such thickness of the carrier reduces the risk of telegraphing of possible imperfections on an underlying surface across the floor panels. This risk is reduced even more as the carrier also comprises a thermoplastic material of the rigid type.

The carrier may also be calibrated, for example, by means of a roller. The roller may relate to an S-roller. The calibrating step may be applied, for example, for calibrating the foamed carrier.

It is also noted that in the case of a multi-layered carrier at least one layer of the carrier is realized on the basis of a thermoplastic material, such as described herein above, whereas the material of the one or more remaining layers may show one or more of the characteristics of the herein above-mentioned thermoplastic material. The plurality of layers of the carrier may or may not have been made equal to each other.

According to a preferred embodiment of the method according to the first special preferred embodiment, the method also comprises the step of providing the carrier with a counter layer on the basis of a thermoplastic material, which is softer than the aforementioned thermoplastic material strewn as a dry-blend. It is noted that by the term "counter layer" a layer is intended which is provided underneath the aforementioned thermoplastic material strewn as a dry-blend, however, does not necessary have to be directly adjacent thereto. As the thermoplastic material of the counter layer should be softer than the aforementioned material strewn as a dry-blend, the thermoplastic material of the counter layer may comprise more plasticizer. Preferably, the thermoplastic material of the counter layer comprises plasticizer in an amount of minimum <NUM> phr, still more preferably in an amount larger than <NUM> phr. The rather soft counter layer may provide new features for the floor panels, such as comfort or sound adsorption, and forms in particular a layer with acoustic features, such as reducing the noise production of the floor panels, for example, when the floor panels are being walked on. The thermoplastic material of the counter layer may or may not comprise the same thermoplastic synthetic material as the thermoplastic material strewn as a dry-blend. The thermoplastic synthetic material of the counter layer may relate, for example, to PVC, preferably PVC of the soft or supple type. The thermoplastic material of the counter layer can be foamed and to this aim can be provided with one or more of the blowing agents already described herein above.

The step of providing the carrier with the counter layer preferably is performed in-line with the already above-mentioned steps of strewing and consolidating the material strewn as a dry-blend. Although the counter layer preferably is applied prior to consolidating the material strewn as a dry-blend, wherein the counter layer then can be bonded to the material strewn as a dry-blend during the consolidating process, the invention does not exclude that the counter layer is provided on the already compressed and pressed material strewn as a dry-blend.

Most preferably, the step of providing the counter layer comprises strewing the thermoplastic material of the counter layer and consolidating the strewn thermoplastic material of the counter layer. Moreover, consolidating the strewn thermoplastic material of the counter layer preferably is performed during the step of consolidating the thermoplastic material strewn as a dry-blend. This offers the advantage that providing the counter layer simply can be integrated into the herein-above described method. For example, only an additional strewing device has to be provided, which then performs the strewing of the thermoplastic material of the counter layer. The thermoplastic material of the counter layer can be strewn as a dry-blend, however, can also be strewn in any other form, for example, as a granulate.

The aforementioned steps of the method according to the first special preferred embodiment preferably are performed as a continuous process.

It is also noted that applying a strewing process for foaming a carrier on the basis of rigid thermoplastic material as such forms a preferred embodiment of the invention, independent of the characteristic that the thermoplastic material is strewn as a dry-blend. A carrier on the basis of foamed, rigid thermoplastic material offers the advantage that particularly stable and economical floor panels can be obtained, wherein moreover the risk of telegraphing of possible imperfections on an underlying surface across the floor panels can be minimized. Apart therefrom, the strewing and consolidating process allows manufacturing such floor panels in a particularly efficient manner, in view of the fact that the strewing process, on the one hand, allows a smooth processing of rigid thermoplastic materials and, on the other hand, provides excellent conditions for foaming the thermoplastic material.

Thus, the present invention, according to a second special preferred embodiment thereof, relates to a method for manufacturing floor panels, as defined in claim <NUM>, wherein the floor panels comprise a carrier on the basis of thermoplastic material, and a top layer provided on the carrier; with the characteristic that the method comprises at least the steps of strewing the thermoplastic material and consolidating the strewn thermoplastic material; that the method also comprises the step of foaming the thermoplastic material and the thermoplastic material to this aim is provided with a chemical blowing agent; and that the thermoplastic material comprises a plasticizer in an amount of maximum <NUM> phr, preferably in an amount smaller than <NUM> phr, and still more preferably in an amount between <NUM> and <NUM> phr.

In a particularly preferred embodiment of the method according to the second special preferred embodiment, the method also comprises the step of providing the carrier with a reinforcement layer, more particularly a glass fiber cloth or glass fleece. A carrier manufactured in this manner allows obtaining an extremely stable floor panel.

It is also noted that the herein-above described second special preferred embodiment of the invention can be combined with one or more of the characteristics which are described herein above within the scope of the first special preferred embodiment, independent of the characteristic that the thermoplastic material is strewn as a dry-blend.

It is also noted that applying a strewing process for foaming a carrier on the basis of thermoplastic material by means of a chemical blowing agent forms the independent inventive idea of the invention. Thus, the present invention, as defined in claim <NUM>, relates to a method for manufacturing floor panels, wherein the floor panels comprise a carrier on the basis of thermoplastic material and a top layer provided on the carrier, with the characteristic that the method comprises at least the steps of strewing the thermoplastic material and consolidating the strewn thermoplastic material; that the method also comprises the step of foaming the thermoplastic material, and the thermoplastic material to this aim is provided with a chemical blowing agent. Although the use of a chemical blowing agent for foaming polymer materials is known as such, for example, in an extrusion or injection molding process, the inventor has found that such chemical blowing agent also provides for an excellent foaming when said blowing agent is applied in a strewing process. Apart therefrom, it has shown that such chemical blowing agent behaves excellently in conditions which are typical for the consolidating process subsequent to strewing.

It is also noted that the invention can be combined with one or more of the characteristics which are described herein above within the scope of the first special preferred embodiment, independent of the characteristic that the thermoplastic material is strewn as a dry-blend.

Of course, the carrier, as described herein above in the method of the first and the second special preferred embodiment, still has to be processed with other material, whether or not in layers, for forming the final floor panels. Generally, this further treatment can take place according to various manners, wherein, for connecting the other material to the carrier, various processes can be applied, such as, amongst others, laminating and coating processes.

According to a first possibility, by means of heat and pressure the carrier, at least on the surface, is fused together with one or more further layers, such as a printed decor film and/or a wear layer and/or a further thermoplastic layer. According to a second possibility, the material of one or more further layers, in particular one or more further thermoplastic layers, can be applied in liquid or pasty form by calendering them or providing them on the carrier in any other manner. According to a third possibility, one or more further layers are bonded to the carrier by means of an adhesive agent or glue.

The top layer preferably comprises at least a decor and a transparent or translucent wear layer situated on top of the decor.

The decor of the top layer preferably comprises a motif or pattern, more particularly a wood motif or wood pattern, which is realized in form of a print on a synthetic material film, for example, a polyvinyl chloride film, a polyurethane film, a polypropylene film or a polyethylene film. Such decor preferably is bonded to the carrier by means of a thermal laminating process, whether or not together with one or more remaining layers of the top layer, such as the wear layer. Herein, the decor can be provided and laminated onto the carrier as a continuous film, as described as such in PCT/IB2015/<NUM> (published as <CIT>). In the case of such laminating process, preferably an isobaric press is applied, as described as such in <CIT>.

According to another alternative, the decor can be provided as a print on the underside of the wear layer.

The wear layer preferably is a synthetic material-based wear layer, which either is provided as a film, whether or not together with said printed film, for example, by means of a thermal laminating process, or is applied in liquid condition and subsequently is solidified on the carrier. In the case that the wear layer comprises a film, this preferably relates to a thermoplastic film, in particularly a polyvinyl chloride film, a polyurethane film, a polypropylene film or a polyethylene film.

In accordance with the invention, the top layer comprises a thermoplastic backing layer. It is noted that by the term "thermoplastic backing layer", a backing layer is meant which is realized on the basis of a thermoplastic material. The thermoplastic backing layer may be fused together with the carrier under the influence of pressure and temperature, whether or not together with the herein above-mentioned film and/or the wear layer, or may be applied in liquid or pasty form by calendering it or providing it on the carrier in any other manner.

The thermoplastic backing layer preferably is provided on the carrier as a not-strewn layer, preferably after the thermoplastic material of the carrier is consolidated. In that the thermoplastic backing layer is provided in a different manner than the earlier-mentioned thermoplastic material, a greater freedom in view of the process configuration is obtained, wherein strewn and not-strewn layers can be combined in an advantageous manner. Preferably, the thermoplastic backing layer is provided in the form of a sheet or film, more particularly by means of calendering. According to an alternative, the backing layer can be applied by means of an adhesive agent or glue, or also by means of thermal lamination.

The thermoplastic backing layer can show one or more of the following characteristics:.

That a supple backing layer is applied, i.e. a backing layer with a supple thermoplastic, for example, soft or supple PVC, has the advantage that the floor panels can be provided with a certain flexibility. Such flexibility can contribute to the ease of installation of the floor panels, as well as, for example, to a reduction of the noise production of the floor panels, for example, when the floor panels are being walked on. Preferably, the thermoplastic material of the backing layer comprises a plasticizer in an amount of maximum <NUM> phr, and more particularly in an amount larger than <NUM> phr.

Herein, it is also noted that the composition of the thermoplastic material of the backing layer may or may not be equal to the composition of the herein-above mentioned thermoplastic material which is strewn as a dry-blend, independent of the manner in which the backing layer is applied, however, preferably is different therefrom.

The top layer can be finished with a lacquer layer, which is provided on said wear layer and/or said decor as a liquid layer and subsequently has solidified. Preferably, this relates to a lacquer layer which can be solidified by UV light or excimer radiation. Preferably, a lacquer layer is provided on top of the possible wear layer.

In a particular embodiment, the top layer is realized such as the first semi-finished product described in <CIT>, wherein this first semi-finished product is combined with the carrier as described herein above, by means of laminating.

Although the top layer preferably is applied after the carrier is formed or consolidated, the invention does not exclude that the top layer is entirely or partially provided before the carrier is formed. So, one or more layers of the top layer can be applied prior to consolidating the carrier and subsequently can be bonded to the carrier during the consolidating process.

The top layer can also be provided with embossments, which may or may not be performed in register with the possibly present decor. To this aim, a roller can be applied, as described as such in <CIT> (published as <CIT>). The embossments provide the floor panels with a relief, such that they can simulate a real wood structure even better. The embossments can be performed, for example, according to a wood nerve pattern.

According to the invention, it is possible that the carrier, whether or not together with still other layers, forms a material web from which floor panels are obtained by dividing, more particularly by cutting, to preferably oblong rectangular or square floor panels.

Preferably, the invention, for example according to its first and its second preferred embodiment, is applied for manufacturing floor panels which, on at least two opposite edges, are provided with mechanical coupling means, more particularly coupling parts, which allow that two of such floor panels can be coupled to each other in such a manner that a locking is obtained in a vertical direction perpendicular to the plane of the coupled panels as well as in a horizontal direction perpendicular to the coupled edges and in the plane of the floor panels.

Preferably, the coupling means show one or a combination of the following characteristics:.

Preferably, the aforementioned coupling means or coupling parts, or at least a part of the coupling means or coupling parts, are provided in the material of the carrier, more particularly by means of a milling treatment with rotating milling tools. In particularly, the coupling means are realized at least partially in the herein above-described thermoplastic material strewn as a dry-blend, which shows excellent features for this purpose.

The floor panels preferably relate to oblong rectangular or square floor panels, which on their both pairs of opposite edges are provided with coupling means or coupling parts, as described herein above.

However, it is not excluded that the floor panels at their edges are free from coupling means or coupling parts, wherein these floor panels then are intended for being glued with their underside on an underlying surface or for being loosely installed.

With the intention of better showing the characteristics of the invention, herein below, as an example without any limitative character, some preferred embodiments are described, with reference to the accompanying drawings, wherein:.

<FIG> represents a floor panel <NUM> obtained according to the invention. In the example, the floor panel <NUM> is rectangular and oblong and comprises a pair of long sides <NUM>-<NUM> and a pair of short sides <NUM>-<NUM>.

<FIG> represents a cross-section according to the line II-II in <FIG>. From the cross-section, it is clear that floor panel <NUM> is composed of a, in this case multi-layered, carrier <NUM> and a top layer <NUM> provided on the carrier <NUM>. The carrier <NUM> is realized on the basis of thermoplastic material.

The carrier <NUM> here comprises two layers 9A and 9B, which both are realized on the basis of thermoplastic material. Both layers 9A and 9B comprise a strewn and pressed dry-blend. The thermoplastic material of at least one of the layers 9A-9B, and preferably of both layers 9A-9B, shows the following characteristics:.

The layers 9A and/or 9B are foamed, wherein the foaming of the layers are performed such as described in the introduction.

Further, the carrier <NUM> comprises a glass fiber fleece <NUM>, which in the example is enclosed in between the layers 9A-9B.

The carrier <NUM> further also comprises a counter layer <NUM>, which is provided on the underside <NUM> of the layer 9B and also is realized on the basis of PVC. In particular, this relates to PVC of the soft or supple type. The counter layer <NUM> is optional and it is, for example, possible that one of the layers 9A-9B, namely the lowermost layer 9B, forms the underside of the carrier <NUM> and thus also the underside of the floor panel <NUM>.

The top layer <NUM> provided on the carrier <NUM> comprises a printed decor film <NUM> and a transparent wear layer <NUM> on the basis of thermoplastic material. The top layer <NUM> further also comprises a thermoplastic backing layer <NUM> situated underneath the decor film <NUM>. In the example, the backing layer <NUM>, the decor film <NUM> as well as the wear layer <NUM> are realized on the basis of PVC. Herein, the backing layer preferably is realized on the basis of soft or supple PVC.

In the example, the decor film <NUM> is provided with a print with a wood pattern <NUM>, wherein per floor panel <NUM> each time the image of a single wooden plank is provided.

<FIG> further also represents that the carrier <NUM> has a thickness T which forms at least <NUM> percent, and here even more than half of the thickness T1 of the floor panel <NUM>.

Further, the floor panel <NUM> of the example is provided with mechanical coupling means or coupling parts <NUM> on both opposite edges <NUM>-<NUM>. <FIG> shows that at least the mechanical coupling parts <NUM> on the long pair of edges <NUM>-<NUM> allow that two of such floor panels <NUM> can be coupled to each other, such that a locking is created in a vertical direction V1 perpendicular to the plane of the coupled floor panels <NUM>, as well as in a horizontal direction H1 perpendicular to the coupled edges <NUM>-<NUM> and in the plane of the floor panels <NUM>. The illustrated coupling means <NUM> show the feature that they are substantially realized as a tongue <NUM> and a groove <NUM> bordered by an upper lip <NUM> and a lower lip <NUM>, wherein this tongue <NUM> and groove <NUM> are substantially responsible for the locking in said vertical direction V1, and wherein the tongue <NUM> and the groove <NUM> are provided with additional locking parts <NUM>-<NUM>, substantially responsible for the locking in said horizontal direction H1. In this case, the locking parts comprise a protrusion <NUM> on the underside of the tongue <NUM> and a cooperating therewith recess <NUM> in the lower lip <NUM>. The coupling means <NUM> represented here allow at least a coupling by means of a turning movement W along the respective edges <NUM>-<NUM>. The mechanical coupling means <NUM> are substantially realized in the layers 9A-9B, which enclose the glass fiber layer <NUM>. In the example, they are provided by means of a milling treatment, for example, by means of rotating tools.

<FIG> represents some steps of a method according to the invention. The method can be applied for manufacturing the floor panel <NUM> from <FIG>. In particular, some steps are represented for forming the carrier <NUM>.

For forming the layers 9A-9B, strewing devices <NUM> are applied which perform the strewing of the dry-blend <NUM> of which the layers 9A-9B are composed. The strewing devices <NUM> deposit the dry-blend <NUM> of the layer 9B and the layer 9A, respectively, on a transport device <NUM> and the glass fiber layer <NUM>, which can be supplied to the layer 9B, for example, from a roll.

Subsequently, the strewn dry-blend <NUM> is consolidated between the belts <NUM> of a continuous press device <NUM> under the influence of pressure and temperature. Hereby, the dry-blend <NUM> is fed along one or more heating devices <NUM> and possibly can be cooled again after the press treatment or at the end of the press treatment. By cooling, it is obtained that the pressed plates, sheets or layers are relatively fast in a manageable condition for further processing.

The dry-blend <NUM> of the layers 9A and/or 9B is foamed and to this end is provided with a chemical blowing agent. For the foaming of the layers 9A-9B, or at least the partial foaming thereof, the press device <NUM> as well as the heating devices <NUM> are applied.

<FIG> further also represents that simultaneously with pressing, a further layer, in this case at least the decor film <NUM>, can be provided or integrated by supplying this on the dry-blend <NUM> in the press treatment. Instead of a decor film, in accordance with the invention, this may relate to a backing layer <NUM>. This may also relate to an assembly of layers already laminated to each other, such as an already entirely or partially composed top layer <NUM>, which, for example, comprises at least a backing layer <NUM> and a decor film <NUM>, or the backing layer <NUM>, decor film <NUM> as well as the wear layer <NUM>. A possible superficial lacquer layer preferably is provided after the press treatment. This is not represented here.

Although <FIG> represents two strewing devices <NUM>, according to the invention it is not excluded that only one strewing device <NUM> is provided. This strewing device <NUM> then is applied for strewing the dry-blend <NUM>.

It is also noted that the invention does not exclude that only one of the strewing devices <NUM> from <FIG> is applied for strewing a dry-blend <NUM>, whereas the other strewing device <NUM> can be applied, for example, for strewing a granulate or for strewing thermoplastic material in any other form.

Also, the invention does not exclude that more than two strewing devices <NUM>, for example, a third and a fourth strewing device, are provided.

Further, it is clear that, in case that a plurality of strewing devices <NUM> are applied, these strewing devices <NUM> can deposit thermoplastic material with a mutually different composition and/or average particle size.

It is also noted that the carrier <NUM> which is formed by means of the steps represented in <FIG> can be processed further for forming the final floor panels. So, a top layer can also be provided on top of this carrier <NUM>, and the carrier itself can also be provided with a counter layer, as described in the introduction.

In <FIG>, some steps are represented of an alternative, however, also preferred method according to the invention.

Two layers 9A-9B are strewn by means of the strewing devices <NUM>. At least one of the two layers 9A-9B comprises a thermoplastic material strewn as a dry-blend <NUM>. In the example, both layers 9A-9B comprise a strewn dry-blend <NUM>. The strewing devices <NUM> strew the dry-blend <NUM> of the first layer 9A and the second layer 9A, respectively, onto the transport device <NUM> and the layer 9B.

Further, a glass fiber layer <NUM> is provided on the upper layer 9A. This glass fiber layer <NUM> can be supplied from on a roll.

Subsequently, the strewn layers 9A-9B, together with the glass fiber layer <NUM>, are transported between the conveyor belts <NUM> and <NUM> along one or more heating devices <NUM>. The heating devices <NUM> are applied for melting the layers 9A-9B or at least for melting them at least partially. Also, the heating devices <NUM> are employed for foaming the layers 9A and/or 9B.

Thereafter, the layers 9A-9B, together with the glass fiber layer <NUM>, are pressed by means of the press unit <NUM>. The glass fiber layer <NUM> is bonded under pressure to the layer 9A by means of the adhesive properties of the molten layer 9A. the glass fiber layer <NUM> here is directly supported by a press element, such as a press platen or a pressing belt, as described as such in the document with application number <CIT>. Subsequently, the layers 9A-9B and the glass fiber layer <NUM> are transported along cooling installations <NUM>.

After the press treatment, in the example of <FIG> also a backing layer <NUM> is provided, being on the basis of thermoplastic material, with a preferably soft or supple thermoplastic. The thermoplastic material of the backing layer <NUM> is melted and pressed to a sheet, after which it is pressed together with the layers 9A-9B and the glass fiber layer <NUM> by means of calendaring rolls <NUM>.

Claim 1:
Method for manufacturing floor panels, wherein the floor panels (<NUM>) comprise a carrier (<NUM>) on the basis of thermoplastic material and a top layer (<NUM>) provided on the carrier (<NUM>); wherein the method comprises at least the steps of strewing the thermoplastic material and consolidating the strewn thermoplastic material, and wherein the top layer (<NUM>) comprises a thermoplastic backing layer (<NUM>), which preferably is of the supple or soft type and to this aim more particularly comprises a supple or soft thermoplastic, for example, supple or soft polyvinyl chloride
characterized in that the method comprises the step of foaming the thermoplastic material, and that the thermoplastic material to this aim is provided with a chemical blowing agent, and in that said step of foaming is performed during said consolidating the strewn thermoplastic material.