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Title:
COMPOSITIONS FOR THE MANUFACTURE OF FLOORING ELEMENTS
Document Type and Number:
WIPO Patent Application WO/2017/191319
Kind Code:
A2
Abstract:
The present invention provides a composition for manufacturing a flooring element comprising cementitious binding material, polymeric fibres, cellulosic fibres, and fibrous processing aid, as well as a process for manufacturing such flooring elements.

Inventors:
ENDL, Thomas (Stadtplatz 22a/53, 4840 Vöcklabruck, 4840, AT)
Application Number:
EP2017/060833
Publication Date:
November 09, 2017
Filing Date:
May 05, 2017
Export Citation:
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Assignee:
SWISSPEARL GROUP AG (Eternitstrasse 3, 8837 Niederurnen, 8837, CH)
International Classes:
C04B28/02; B28B1/52; B28B11/12; C04B28/04; E04F15/10
Attorney, Agent or Firm:
SCHMITZ, Joseph (Postfach 1772, 8027 Zürich, 8027, CH)
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Claims:
CLAIMS

1. A composition for manufacturing a flooring element comprising

a. cementitious binding material,

b. polymeric fibres,

c. cellulosic fibres, and

d. fibrous processing aid.

2. The composition according to claim 1, wherein the polymeric fibres are present of from 1.5 to 3, preferably of from 1.7 to 2.3 dry weight percent, and/or the cellulosic fibres are present of from 1.5 to 6 dry weight percent, and/or the fibrous processing aid is present of from 1.5-6, preferably of from 1.5 to 4 dry weight percent.

3. The composition according to claim 1 or 2, wherein the polymeric fibers are chosen from fibres having a tenacity of more than 1000 mPa and/or a young modulus of more than 30 GPa, and preferably are made of polyacrylonitrile (PAN), polypropylene (PP) or polyvinyl alcohol (PVA), and preferably are made of polyvinyl alcohol (PVA).

4. The composition according to any preceding claim 1, wherein the cellulosic fibres are chosen from synthetic or natural cellulosic fibres, and preferably are chosen from natural cellulosic fibres such as virgin or recycled wood pulp.

5. The composition according to claim 1, wherein the fibrous processing aid comprises fibres made of a polymer, preferably made of polyacrylonitrile (PAN), polypropylene (PP) or polyethylene (PE), and wherein the fibrous processing aid more preferably comprises fibres made of polyethylene (PE).

6. The composition according to claim! , wherein the cementitious binding material is present of from 60 to 90, preferably of from 70 to 75 dry weight percent, and wherein the cementitious binding material is a hydraulic binder material, preferably according to EN 197-1.

7. The composition according to any preceding claim, wherein it further comprises silica, filler, pigments, or additives, or any combination thereof, and if present the filler is present in an amount of less than 30, preferably of from 10 to 20 dry weight percent, and if present the silica is present of in an amount of less than 15, preferably less than 8 dry weight percent.

8. A flooring element or multilayer flooring element, comprising at least a structure made from a cured composition according to any of the claims 1 to 7, and wherein said structure is preferably a load-bearing layer.

9. The flooring element or multilayer flooring element according to claim 8, wherein the structure is obtained by machining, and in particular milling, a blank flooring element made from a cured composition according to any of the claims 1 to 7.

10. An interlocking flooring element or multilayer interlocking flooring element comprising at least a structure, a first interlocking structure and a second interlocking structure made from a cured composition according to any of the claims 1 to 7, and wherein said structure is preferably a load-bearing layer, and wherein the first and the second interlocking structures are made from a cured composition according to any of the claims 1 to 7, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure, and wherein most preferably the load-bearing layer, the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to any of claims 1 to 7. 1. The interlocking flooring element or multilayer interlocking flooring element according to claim 10, wherein the structure, the first interlocking structure and the second interlocking structure is obtained by machining, and in particular milling, a multilayer blank flooring element comprising a cured composition according to any of the claims 1 to 7, wherein preferably the first and second interlocking structures are formed into a tongue having a bulge on one side of the tongue and a groove having a complementary recess on the corresponding side of the groove, respectively.

12. A process for manufacturing a flooring element or interlocking flooring element, comprising the steps of

a. combining a liquid with a composition according to any of claim 1 to 7 and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet,

d. removing the liquid from the wet green sheet and curing the wet green sheet to form a blank flooring element, e. forming the blank flooring element into the flooring element or interlocking flooring element,

wherein the flooring element or interlocking flooring element is formed from the blank flooring element by machining said blank flooring element such as to form a flooring element or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to any of claims 1 to 7.

13. A process for manufacturing a multilayer flooring element or interlocking multilayer flooring element comprising a load-bearing layer at least partially made from a cured composition according to any of claim 1 to 7, comprising the steps of a. combining a liquid with a composition according to any of claim 1 to 7 and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet,

d. removing the liquid from the wet green sheet and curing the wet green sheet to form a solid blank flooring element,

e. applying one or more layers to the solid blank flooring element such as to form a multilayer blank flooring element,

f. forming the multilayer blank flooring element into the multilayer flooring element or interlocking multilayer flooring element comprising a load- bearing layer at least partially made from a cured composition according to any of claim 1 to 7,

wherein the multilayer flooring element or interlocking multilayer flooring element is formed from the multilayer blank flooring element by machining said multilayer blank flooring element such as to form a multilayer flooring element, or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first and second interlocking structures and the load-bearing layer are formed from one body of a cured composition according to any of claims 1 to 7.

14. The process according to claim 12 or 13, wherein the wet green web is pressed to form a wet green sheet at a maximum pressure of 150 bar (15 MPa) to 350 bar (35 MPa).

15. The process according to claim 12 or 13, wherein in step d., the liquid from the wet green sheet is removed by first curing the wet green sheet and subsequently evaporating residual water such as to preferably form a blank flooring element having a moisture content of from 1.5 w/w% to 9 w/w%, more preferably from 3 w/w% to 7 w/w%.

16. Use of a composition according to any claim 1 to 7 in the manufacture of a flooring element, interlocking multilayer flooring element, multilayer flooring element or interlocking multilayer flooring element.

Description:
TITLE COMPOSITIONS FOR THE MANUFACTURE OF FLOORING ELEMENTS

TECHNICAL FIELD

The present invention relates to compositions suitable in the manufacture of flooring elements, a process for the manufacture of said flooring elements, as well as to the use of said composition in such a process for the manufacture.

PRIOR ART

In houses and other types of buildings, the flooring may be made from a vast array of possible materials. Traditionally, most flooring has been wood flooring such as plank or parquet. While even to this day, the look and feel of wood flooring is sought after, the wood flooring that is commercially available suffers from several disadvantages. On one hand, the wood flooring will have a heterogeneous appearance, since no two pieces of wood flooring are be identical, while on the other hand wood flooring suffers from dimensional shrinkage in response to changes in air humidity and/or temperature. This propensity for dimensional shrinkage makes the use of wood flooring impractical, since in the worst case the buildup of tension can lead to significant damage to the wood flooring.

Another inherent drawback of wood flooring is that it constitutes a fire hazard. While it is possible to apply a fire retarding agent to wood flooring, such agents increase the cost of the wood flooring and can furthermore be problematic from a toxicological perspective. The same can be said about composite wood flooring that is based on MDF (medium density fiberboard) and HDF (high density fiberboard). While dimensional shrinkage is improved, these fiberboards release volatile organic components (VOCs) from the resin that is used as a binder material in the MDF and HDF flooring. A further drawback is that these boards cannot be used in wet rooms such as bathrooms floors due to swelling after intense contact with water. Polymer materials are also used for flooring and do not exhibit significant swelling when in contact with water but have the drawback of elongating in response to a temperature rise, for example when sunlight shines directly on the flooring. In any case, flooring based mainly on wood or polymer materials has the problem of being inherently flammable, and while the addition of fire retardants can at least reduce flammability, a toxicological problem can arise due to the chemical composition of the fire retardants. Mineral flooring such as for example fiber cement does not suffer, or to a lesser extent, from the above-mentioned disadvantages, since in general mineral materials do not burn and do not display important dimensional shrinkage in response to changes in humidity or temperature. However, in addition to flammability and dimensional shrinkage, fiber cement needs to fulfill a vast range of mechanical properties when used in flooring applications in order to fully substitute existing flooring types.

Two important properties are strength and hardness. On one hand, the flooring made of fiber cement needs to be able to elastically spring back into its original shape after being deformed and on the other hand, the material needs to be hard enough to be able to be easily be cut into a desired final shape and size with high precision.

Thus, it is desirable to provide alternatives to wood or plastic flooring, such as for example fiber cement compositions, that when formed in to a flooring element, have a lesser propensity for dimensional shrinkage in response to a change of humidity and/or temperature, which are able to elastically spring back into the original shape after being deformed and which are hard enough to be able to be easily be cut into a desired final shape and size with high precision. Additionally fire hazard and the very low emission of VOCs to indoor air of such fiber cement compositions are further advantages. SUMMARY OF THE I VENTION

The above-mentioned problems have been overcome by the present invention which provides a composition for manufacturing flooring elements which are essentially non- flammable, do not display significant dimensional shrinkage in response to a change in humidity and/or temperature, are resilient and capable of elastically springing back into their original shape when deformed in use as flooring, and which can be easily cut into a desired shape and size with high precision, especially when cut by machining.

The present invention thus provides a composition for manufacturing a flooring element comprising a cementitious binding material, polymeric fibres, cellulosic fibres, and fibrous processing aid. The present invention thus further provides a flooring element or multilayer flooring element, comprising at least a structure made from a cured composition according to the above composition, and wherein said structure is preferably a load-bearing layer.

The present invention further provides an interlocking flooring element or multilayer interlocking flooring element comprising at least a structure, a first interlocking structure and a second interlocking structure made from a cured composition to the above composition, and wherein said structure is preferably a load-bearing layer, and wherein the first and the second interlocking structures are made from a cured composition according to the above composition, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure, and wherein most preferably the load-bearing layer, the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to the above composition. The present invention further provides a process for manufacturing a flooring element or interlocking flooring element, comprising the steps of

a. combining a liquid such as water with a composition according to the above composition and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet,

d. removing the liquid from the wet green sheet by for example curing the wet green sheet and optionally drying the wet green sheet to form a blank flooring element, e. forming the blank flooring element into the flooring element or interlocking flooring element,

wherein the flooring element or interlocking flooring element is formed from the blank flooring element by machining said blank flooring element such as to form a flooring element or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to the above composition.

The present invention further provides a process for manufacturing a multilayer flooring element or interlocking multilayer flooring element comprising a load-bearing layer made from a cured composition according to the above composition, comprising the steps of a. combining a liquid such as water with a composition according to the above composition and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet,

d. removing the liquid from the wet green sheet by for example curing the wet green sheet and optionally drying the wet green sheet to form a solid blank flooring element, e. applying one or more layers to the solid blank flooring element such as to form a multilayer blank flooring element,

f. forming the multilayer blank flooring element into the multilayer flooring element or interlocking multilayer flooring element comprising a load-bearing layer at least partially made from a cured composition according to the above composition,

wherein the multilayer flooring element or interlocking multilayer flooring element is formed from the multilayer blank flooring element by machining said multilayer blank flooring element such as to form a multilayer flooring element, or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first and second interlocking structures and the load-bearing layer are formed from one body of a cured composition according to the above composition.

The present invention further provides a use of the composition according to the above composition in the manufacture of any of the flooring element, interlocking multilayer flooring element, multilayer flooring element or interlocking multilayer flooring element.

Further embodiments of the invention are laid down in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the puipose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

Fig. 1 shows the flow chart of the manufacturing process for the flooring elements, in which a scale for the cellulose (1) and a water tank (2) determine the amount of cellulose provided to the pulper and refiner (3), from which the formed cellulose pulp is directed to the cellulose pulp tank (4). From the cellulose pulp tank (4), cellulose pulp is dosed to the mixer II (10). From the polymeric fibre tank (5), polymeric fibre is dosed to the mixer II (10). From the cement slurry mixer I (9), a cement slurry is dosed to the mixer II (10). The cement slurry is prepared by dosing dry cement from the cement tank (6), water from the water tank (8), and filler from the filler tank (7) to the cement slurry mixer I (9) and mixing the dry cement, water and filler. In the mixer II (10), the cement slurry, the cellulose pulp and the polymeric fibre are mixed and dosed to a horizontal mixer III (11), from where the composition for forming the flooring element is conveyed to the Hatschek machine (12) in which the unshaped wet green web (13) is formed and then shaped into a given shape in the stamp (14). Any wet green stamping waste (15) can be recycled into the horizontal mixer III (11) The wet green webs are then conveyed to a stack press (16) to be pressed and form the wet green sheets. The wet green sheets are stacked and subsequently allowed to cure in the curing chamber (17) to form flooring element blanks, after which the individual flooring element blanks are un-stacked (18) and conveyed to a drying apparatus (19), in which the individual flooring element blanks are further dried to desired moisture content. Following the drying, the flooring element blanks may be temporarily stored in a stock (20), and may then be finished into multilayer flooring element blanks in a finishing line (21) for example in the case of multilayer flooring elements. The thus formed flooring element or multilayer flooring element blanks are then formed into flooring elements or multilayer flooring elements by machining said blanks in a milling apparatus (22). The lines (15) and (23) indicate recirculation means that enable to recirculate stamp waste and water, respectively, into the horizontal mixer III (11) and the water tanks (2, 8).

Fig. 2 shows a part of a multilayered interlocking flooring element having an upper layer (24) and a load-bearing-layer (25), where a first interlocking structure is formed into a tongue (27) having a bulge (26) on the lower side of the tongue.

Fig. 3 shows a part of a multilayered interlocking flooring element having an upper layer (24) and a load-bearing-layer (25), where a second interlocking structure which is complementary to a first interlocking structure shown in Fig. 2, is formed into a groove (30) having a recess (31) on the lower side of the groove (30).

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a composition for manufacturing a flooring element, comprising a cementitious binding material, polymeric fibres, cellulosic fibres, and fibrous processing aid.

In the composition for manufacturing a flooring element of the present invention, the cementitious binding material serves the purpose of binding together the polymeric fibres, cellulosic fibres and fibrous processing aid upon curing that leads to the solidification of the cementitious binding material.

The cementitious binding material can be a hydraulic binder material such as cement. Suitable cements are Portland cement, blast-furnace Portland cement, trass cement, and others. Several types of Portland clinker cements can be used, but ordinary Portland cement is particularly preferred. In the case where the cementitious binding material is a hydraulic binder, solidification is brought about in a known manner by addition of water to the hydraulic binder of the composition for manufacturing a flooring element, to allow the hydraulic binder to cure and become adhesive due to a chemical hydration reaction between the hydraulic binder and water.

In preferred embodiment of the composition for manufacturing a flooring element of the present invention, the cementitious binding material is present of from 60 to 90, preferably of from 70 to 75 dry weight percent, and the cementitious binding material is a hydraulic binder material such as Portland cement, more preferably is a hydraulic binder material according to EN 197-1 of the Type I, II, III, IV, and/or V.

In the composition for manufacturing a flooring element of the present invention, the polymeric fibers serve the purpose of reinforcing fibers. Apart from certain mechanical properties, it is also advantageous that the polymeric fibers are made from a suitable polymer having a good resistance against alkaline hydrolytic degradation. Thus, suitable polymers for use in the polymeric fibers are polyolefins in general, and it has been found that fibers made from polyacrylonitrile (PAN), polypropylene (PP) or polyvinyl alcohol (PVA) can be used in composition for manufacturing a flooring element.

In preferred embodiment of the composition for manufacturing a flooring element of the present invention, the polymeric fibres are present of from 1.5 to 3, preferably of from 1.7 to 2.3 dry weight percent. When the amount of polymeric fibers is below the lower limit of 1 dry weight percent, the reinforcing effect achieved in the final flooring elements becomes insufficient, whereas adding more than the upper limit of 3 dry weight percent of polymeric fibres will result in complications of the Hatschek-type manufacturing process. In another preferred embodiment of the composition for manufacturing a flooring element of the present invention, the polymeric fibers are chosen from fibers having a tenacity of more than 8 cN/dtex or of between 8 and 25 cN/dtex, preferably of more than 10 cN/dtex or of between 10 and 25 cN/dtex and/or a young modulus of more than 200 cN/dtex or of between 200 cN/dtex and 500cN/dtex, preferably of more than 220 cN/dtex or of between 220 cN/dtex and 500cN/dtex; and preferably are made of polyacrylonitrile (PAN), polypropylene (PP) or polyvinyl alcohol (PVA), and preferably are made of polyvinyl alcohol (PVA). In another preferred embodiment of the composition for manufacturing a flooring element of the present invention, the polymeric fibers have an average linear mass density of 0,5 to 10 dtex and preferably of from 0,7 to 3 dtex and/or an average length of from 2, or 3, to 10 mm, or more than 3 mm up to 10 mm, and preferably of from 4 to 6 mm. In preferred embodiment, the polymeric fiber length distribution is bimodal, i.e. two different lengths of polymeric fibers are present in the composition for manufacturing a flooring element of the present invention, namely one having a shorter length and one having a longer length.

In a much preferred embodiment of the composition for manufacturing a flooring element of the present invention, the polymeric fibers are made of polyvinyl alcohol (PVA) having a tenacity of more than 8 cN/dtex and/or a young modulus of more than 200 cN/dtex.

In the composition for manufacturing a flooring element of the present invention, the cellulosic fibres, besides serving the purpose of filtration and process aid, can further act as additional reinforcing fibers. In the blank flooring element made from the composition for manufacturing a flooring element, the cellulosic fibers provide a good particle and interlayer bond and so a required hardness which in turn allows the blank flooring element to be cleanly machined with the required precision, Without this bonding and strength effect of the cellulosic fibers, the edges or surfaces formed after machining of the blank flooring element, display imperfections mainly in the form of the polymeric fibers starting to fray. This is not compatible with required aesthetics and can afterwards interfere with the installing of the flooring elements. The cellulosic fibers can be synthetic or natural cellulosic fibers. Examples of synthetic cellulosic fibers are rayon, viscose or surface- modified cellulosic fibers, whereas natural cellulosic fibers can be chosen from pulp, which can either be sourced from plant material such as wood (virgin wood pulp) or be sourced from paper waste streams such as recycled paper or cardboard (recycled wood pulp). Wood pulp can either be used as premanufactured slurry or as dried wood pulp chips or powder.

In preferred embodiment of the composition for manufacturing a flooring element of the present invention, the cellulosic fibres are present of from 1.5 to 6 dry weight percent.

In another preferred embodiment of the composition for manufacturing a flooring element of the present invention, the cellulosic fibres are chosen from synthetic or natural cellulosic fibres, and preferably are chosen from natural cellulosic fibres such as virgin or recycled wood pulp.

In the composition for manufacturing a flooring element of the present invention, the fibrous processing aid serves as filtering aid during the manufacturing process. The fibrous processing aid can comprise, or consist of, polymer fibres of a given length, such as for example of from 0.05 to 3.0 mm, or from 0.05 up to 3.0 mm. The type of polymer can be chosen freely, but as with the polymeric fibres, it is in general advantageous to choose a polymer that is resistant against hydrolysis, for example a polyolefin such as polyacrylonitrile (PAN), polypropylene (PP) or polyethylene (PE).

In a preferred embodiment of the composition for manufacturing a flooring element of the present invention, the fibrous processing aid comprises fibres made of a polymer, preferably made of polyacrylonitrile (PAN), polypropylene (PP) or polyethylene (PE), and wherein the fibrous processing aid more preferably comprises fibres made of polyethylene (PE).

In a preferred embodiment of the composition for manufacturing a flooring element of the present invention, the fibrous processing aid comprises or consists of fibres having an average length of from 0.1 to 2 mm, and more preferably having an average length of 0.5 to 1.5 mm. It is noted that the type of polymer used for the polymeric fibres and fibrous processing aid can in theory be the same, but preferably the polymer of the fibrous processing is different from the polymer of the polymeric fiber. Therefore, in a preferred embodiment of the composition for manufacturing a flooring element of the present invention, the polymer of the fibrous processing is different from the polymer of the polymeric fiber.

In a preferred embodiment of the composition for manufacturing a flooring element of the present invention, the fibrous processing aid is present of from 1.5 to 6, preferably of from 1.5 to 4 dry weight percent.

In a preferred embodiment of the composition for manufacturing a flooring element of the present invention, the composition for manufacturing a flooring element of the present invention may further comprise silica, filler, pigments or additives, or any combination thereof.

If present in the composition for manufacturing a flooring element of the present invention, the silica is present of in an amount of less than 15, preferably less than 8 dry weight percent. The silica serves to control the density of the flooring element and rises the strength and interlayer bond of the flooring element. This can have a favorable impact on strength, thermal and acoustic dampening properties of the flooring element, and can thus be adjusted by controlling the amount of silica in the composition for manufacturing a flooring element. The silica may be supplied in powder form or in a slurry.

In general, the silica useful in the composition for manufacturing a flooring element of the present invention has a particle size of about 50, or 100, to 200 nm. This fine particles are usually agglomerated.

In general, the silica useful in the composition for manufacturing a flooring element of the present invention is amorphous silica.

In general, the silica useful in the composition for manufacturing a flooring element of the present invention has a density at 20°C of no more than 1000 kg/m 3 , and preferably has a density of from 150 to 750 kg/m . If present in the composition for manufacturing a flooring element of the present invention, the filler is present in an amount of less than 30, preferably of from 10 to 20 dry weight percent.

In general, the filler useful in the composition for manufacturing a flooring element of the present invention is chosen from calcium carbonate (GCC or PCC), e.g. limestone, chalkstone, chalk, or marble. If present in the composition for manufacturing a flooring element of the present invention, the additive is preferably chosen from wollastonite, mica to improve fire behavior, strength and allow ease of production.

The present invention further provides a flooring element comprising at least a structure made from any of the above-mentioned compositions. The structure made from the above- mentioned compositions, such as for example a load-bearing layer of the flooring element may have a density of from 1600 to 1875 kg/m 3 .

It is understood that in general, when using the term "made from any of the above- mentioned compositions" or "formed from any of the above-mentioned compositions" in conjunction with the term "flooring element", "structure", "interlocking structure", "interlocking flooring element", "interlocking structure", or "load-bearing layer", thus refers to the cured and/or dried slurry of the above-mentioned compositions. The flooring element can be formed in part through known processes for manufacturing fiberboard such as the Hatschek process, both in the air-cured version and the steam-cured version or the flow on process, to the extent that such a process yields a blank structure, or blank flooring element. The blank flooring element is then further machined according to the process of the present invention to yield either a machined structure that is then incorporated in to a more complex flooring element such as for example a multilayer flooring element, or to yield a flooring element itself, respectively. In a preferred embodiment the flooring element is incorporated in a more complex flooring element and is then further machined.

A flooring element according to the present invention may thus be formed essentially integrally from the composition for manufacturing a flooring element of the present invention, and is preferably machined, and in particular milled, to the desired shape. Alternatively, a load-bearing layer may be formed from the composition for manufacturing a flooring element of the present invention and incorporated into a more complex flooring elements, such as for example a multilayer flooring element. Also in this case, the load- bearing layer is preferably machined, and in particular milled, to the desired shape together with the additional layer comprised in the multilayer flooring element.

The present invention further provides an interlocking flooring element or multilayer interlocking flooring element comprising at least a structure, a first interlocking structure and a second interlocking structure made from a cured composition to the above composition, and wherein said structure is preferably a load-bearing layer, and wherein the first and the second interlocking structures are made from a cured composition according to the above composition, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure, and wherein most preferably the load-bearing layer, the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to the above composition. The first and second interlocking elements may be arranged on opposite sides of the interlocking flooring element or multilayer interlocking flooring element such as to join adjacent interlocking flooring elements by joining the first interlocking element of an interlocking flooring element with the second interlocking element of an adjacent interlocking flooring element.

For example, the first interlocking structure and at least a second interlocking structure can be a first shoulder and cheek and a second shoulder and cheek capable of forming a lap joint when the two or more interlocking flooring elements are installed side by side, or can be a first tongue structure and a second groove structure capable of forming a tongue and groove joint when the two or more interlocking flooring elements are installed side by side.

In a preferred embodiment of the flooring element or the interlocking flooring element according to the present invention, the flooring element or interlocking flooring element is essentially integrally formed from a composition for manufacturing a flooring element described above, and is preferably machined, and in particular milled, to the desired shape. In another preferred embodiment of the flooring element or interlocking flooring element according to the present invention, the flooring element or interlocking flooring element is a multilayered flooring element or interlocking flooring element where at least a load- bearing layer is formed from a composition for manufacturing a flooring element described above.

In a more preferred embodiment of the flooring element or interlocking flooring element according to the present invention, the flooring element or interlocking flooring element is a multilayered flooring element or interlocking flooring element comprising a top layer, a load-bearing middle layer formed from a composition for manufacturing a flooring element described above, and optionally a bottom layer, where the top layer may for example be a decorative layer, a wear-resistant layer or a watertight layer and the bottom layer may for example be provided with fastening elements such as for example adhesive strips or preformed locking means designed to lock onto a underlying ground structure, and where in the case of the interlocking flooring element, the first and second interlocking structures are formed from a composition for manufacturing a flooring element described above, and are preferably machined, and in particular milled, to the desired shape, and where most preferably at least the first and second interlocking structures and the load- bearing layer are formed from one body of from a composition for manufacturing a flooring element described above.

In a much preferred embodiment of the multilayered interlocking flooring element, the first and second interlocking structures are formed into a tongue having a bulge on one side of the tongue and a groove having a recess on the corresponding side of the groove, respectively, such that when adjacent multilayered interlocking flooring elements are joined during assembly of a flooring, the bulge of the tongue of a first interlocking flooring element is fitted into recess of the groove of an adjacent interlocking flooring element. In order to assemble the flooring, two adjoining multilayered interlocking flooring elements are forced laterally against each other such that the tongue and groove snap together by elastically deforming for a moment. The fitting of the bulge of the tongue into the recess of the groove allows the lateral locking of two adjoining multilayered interlocking flooring elements. By using the composition for manufacturing a flooring element described above, it becomes possible to provide a material that can be easily machined, but which also has the elastic properties for the above-described assembly in which the tongue and groove snap together by elastically deforming.

In a most preferred embodiment of the multilayered interlocking flooring element, the first and second interlocking structures are formed into a tongue having a bulge on the lower side of the tongue and a groove having a recess on the lower side of the groove, respectively, such that when adjacent multilayered interlocking flooring elements are joined during assembly of a flooring, the bulge of the tongue of a first interlocking flooring element is fitted into the recess of the groove of an adjacent interlocking flooring element.

The flooring element according to the present invention may have any form suitable to form a flooring, and the form may for example be that of a tile or a plank, which flooring element may optionally display pre-formed perforations that allow to fasten the flooring element, for example nail, screw or bolt to the underlying ground structure.

In a more preferred embodiment of the multilayered flooring element or interlocking flooring element according to the present invention, the multilayered flooring element or multilayered interlocking flooring element comprises a polymer top layer a load-bearing middle layer formed from a composition for manufacturing a flooring element described above, wherein and having a thickness of from 2 to 20 mm.

The present invention further provides a process for manufacturing a flooring element or interlocking flooring element, comprising the steps of

a. combining a liquid such as water with a composition according to the above composition and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet, d. removing the liquid from the wet green sheet by for example curing the wet green sheet and optionally drying the wet green sheet to form a blank flooring element, e. forming the blank flooring element into the flooring element or interlocking flooring element,

wherein the flooring element or interlocking flooring element is formed from the blank flooring element by machining said blank flooring element such as to form a flooring element or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first interlocking structure and the second interlocking structure are integrally formed from one body of a cured composition according to the above composition.

In the process for manufacturing a flooring element or interlocking flooring element of the present invention made from the above-mentioned composition, the steps a. to d. correspond in essence, but are not limited to, the Hatschek process, which is well-known to the person skilled in the art of manufacturing fiber cement panels or cement board. A schematic representation of the Hatschek process is depicted in the drawings section in more detail for illustrative purposes. While the Hatscheck process allows for some degree of control with respect to the shape of the solid blank flooring element, the means for controlling the shape of the solid blank flooring element are however insufficient to achieve the degree of shaping precision required in flooring application, and in any case are unsuited to form interlocking structures of an interlocking flooring element. Therefore, the solid blank flooring elements must be shaped through more precise forming methods.

In the process for manufacturing a flooring element or interlocking flooring element of the present invention made from the above-mentioned composition, the flooring element is formed from the blank flooring element that is yielded after removing the liquid from the wet green sheet, i.e. after curing and/or drying of the wet green sheet, by machining said solid blank flooring element into the desired shape. This step may be performed in-line or on-site in the manufacturing facility, or alternatively blank flooring elements may be stored and then transported to a machining or milling facility to be machined or milled into the desired shape. 10

In an embodiment of the process for manufacturing a flooring element, in step d. the liquid from the cured wet green sheet is removed, e.g. by curing and/or subsequently drying, such as to form a blank flooring element preferably having a moisture content of from 1.5 to 9 w/w% or more preferably of 3 to 7 w/w%.

In an embodiment of the process for manufacturing a flooring element of the present invention made from the above-mentioned composition, the wet green web is pressed to form a wet green sheet at a maximum pressure of from 150 bar (15 MPa) to 400 bar (40 MPa), preferably for at least 30 seconds if a wet green web is pressed alone, or for at least 5 minutes if a large stack of 30 to 200 green webs is jointly pressed.

The present invention further provides a process for manufacturing a multilayer flooring element or interlocking multilayer flooring element comprising a load-bearing layer made from a cured composition according to the above composition, comprising the steps of a. combining a liquid such as water with a composition according to the above composition and optionally silica, filler, pigments, additives, or any combination thereof, to form a slurry,

b. forming the slurry into a web such to form a wet green web,

c. pressing the wet green web to form a wet green sheet,

d. removing the liquid from the wet green sheet by for example curing the wet green sheet and optionally drying the wet green sheet to form a solid blank flooring element, e. applying one or more layers to the solid blank flooring element such as to form a multilayer blank flooring element,

f. forming the multilayer blank flooring element into the multilayer flooring element or interlocking multilayer flooring element comprising a load-bearing layer at least partially made from a cured composition according to the above composition,

wherein the multilayer flooring element or interlocking multilayer flooring element is formed from the multilayer blank flooring element by machining said multilayer blank flooring element such as to form a multilayer flooring element, or interlocking multilayer flooring element, said interlocking multilayer flooring element comprising at least a first interlocking structure and at least a second interlocking structure, and wherein preferably the form of the first interlocking structure is essentially complementary to the form of the second interlocking structure and/or preferably the first and second interlocking structures and the load-bearing layer are formed from one body of a cured composition according to the above composition. The step of applying one or more layers to the solid blank flooring element such as to form a multilayer blank flooring element can be carried out through different methods, such as for example, but not limited to, calendaring, spray-coating, laminating or roller coating, gluing and such.

EXAMPLES

Compositions for the manufacturing a flooring element comprising 75% dry weight of the cement CEM I 42.5 R were combined with 1.7% dry weight of polymeric fiber PVA having a linear density of 2 dtex and an average length of 4 mm, 3% dry weight of PE fibrid , 2% dry weight cellulose and 18.3% dry weight of limestone.

Compositions for the manufacturing a flooring elements were provided as specified in Table 1 and were processed according to the Hatschek-type process depicted in Fig. 1 to be formed into testing blank flooring elements for which milling behavior, climatic behavior, elasticity of board and elasticity of interlocking were recorded. In examples 1 to 4, the process parameters of pressing and drying were varied while composition was kept nearly identical, whereas in examples 5 to 7 the composition was varied while keeping the process parameters identical.

In example 1 and 2, none, or little pressure (5 MPa), was applied on the wet green web to form a wet green sheet, whereas in the case of Example 3 and , the pressure applied was 20 Mpa.

As a consequence of little or no pressure during the step of forming the wet green sheet and of furthermore no drying, the testing flooring elements obtained according to Example 1 and 2 showed poor milling behavior and unsuitable or barely sufficient climatic behavior. In contrast, the testing flooring elements obtained according to Example 4, in which a pressure of 20 MPa was applied to form a wet green sheet and in which the cured element was dried as well to a moisture content of about 3 to 5 w/w% displayed good milling behavior without fraying of the fiber. With respect to elasticity of the board and elasticity of the interlocking element, there were no significant differences between Examples 1, 2, 3 and 4 .

For examples 5, 6 and 7, the pressure applied on the wet green web to form a wet green sheet was kept at 20 MPa and after curing, the thus obtained testing blank elements were dried to a moisture content of about 3 to 4 w/w%. In example 5, the replacement of some of the limestone with 8% dry weight silica fume impaired the climatic behavior of the testing blank elements. A decrease to 8% dry weight silica fume and an increase of the cellulose fiber to 3 % dry weight, as well as an increase to 2 % dry weight in PVA fiber yielded a blank element with overall good properties, as shown for example 6. In example 7, the content of the PVA fiber and the cellulose fiber were too low at 1% dry weight, along with a high content of silica fume, and none of suitable properties were reached.

Table 1 :

Evaluation

++ good + suitable poor not suitable

LIST OF REFERENCE SIGNS

1.. .scale for the cellulose

2.. .water tank

5 3.. ..pulper and refiner

4.. ..cellulose pulp tank

5. , ..polymeric fibre tank

6.. ..cement tank

7. ..filler tank

10 8. ..water tank

9. ..mixer I

10.. .mixer II

11 .. .horizontal mixer III

12.. ..Hatschek machine

15 13.. , .wet green web

14. , ..stamp

15. ..stamping waste

16. ..stack press

17. ..curing chamber

20 18. ..blanks are un-stacked

19. ..drying apparatus

20. ..stock

21 . ..finishing line

22. ..milling apparatus

25 23. ..recirculation

24. ..top layer

25. ..load-bearing layer

26. ..bulge

27. ..tongue

30 28. ..groove

29. ..recess