Patent Publication Number: US-2013236683-A1

Title: Laminated floor covering

Description:
TECHNICAL FIELD 
     The present invention relates to a laminated floor covering such as a carpet or carpet tile and to a method for making the laminated floor covering. 
     BACKGROUND OF THE INVENTION 
     Carpets, such as free-lay carpet or backed carpet tiles are typically prepared as either a tufted or a fusion bonded carpet material having a wear fibrous or pile surface from which pile yarns upwardly project. Carpet tiles differ from the production of ordinary tufted or other fibrous-faced carpets because there is no requirement on a typical carpet for a heavy backing layer. In a carpet tile, a rigid stabilized mass of a thermoplastic backing layer is required in order to hold down the carpet tile so that it can function as a free-lay carpet tile. Generally, the backing layer has a high filler content (e.g., limestone) and is employed with various scrim materials such as glass fibres, polyester or a combinations thereof, to impart dimensional stability. Generally the thermoplastic backing layer is one or more polyvinyl chloride layers. 
     As an example, a tufted carpet tile generally comprises a primary backing base sheet material such as polyester or polypropylene having a plurality of tufted yarns such as Nylon® through the primary backing to form a wear surface of loop or cut pile (carpet pile). The primary backing is used to tuft the carpet yarn into and to provide the required top cloth of the product. A precoat of a latex type material such as EVA (polyethylene vinyl acetate) or carboxylated styrene-butadiene-styrene may be applied on the back (underside) surface to bond the yarn to the primary backing and to aid in the securing of the primary backing to the backing layer. The backing layer may be comprised of a first PVC layer, a fiberglass layer and a second PVC layer (reback layer)—the first layer of PVC bonding the primary backing to the fiberglass layer, the fiberglass layer ensuring dimensional stability of the carpet tile and the second layer of PVC gluing the layers above it and providing the final backing of the carpet tile. 
     In an alternative construction of the above carpet tiles, the PVC layer is replaced with a bitumen layer. 
     Fusion-bonded carpet generally has a similar backing to tufted carpet except that the fusion-bonded carpet has a plurality of cut pile yarns of nylon or other suitable fibrous material implanted in an adhesive layer, particularly thermoplastic such as PVC or hot-melt adhesive, which may be further laminated to a reinforcement or substrate layer of a woven or non-woven material such as fibreglass, Nylon®, polypropylene or polyester. The plurality of fibrous yarns are bonded to and extend generally upright from the adhesive base layer to form the wear surface. 
     The above constructions suffer from the disadvantages that the carpet and carpet tiles are made from environmentally unfriendly materials. For example Nylon® use in the fibrous or pile surface is made from oil and is a non-renewable resource. 
     It would be desirable to provide a carpet or carpet tile which is formed from more environmentally friendly materials. 
     OBJECT OF THE INVENTION 
     It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages or at least provide a suitable alternative. 
     DEFINITIONS 
     The following are some definitions that may be helpful in understanding the description of the present invention: These are intended as general definitions and should in no way limit the scope of the present invention to those terms alone, but are put forth for a better understanding of the following description. 
     Unless the context requires otherwise or specifically stated to the contrary, integers, steps, or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements. 
     Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers, but not the exclusion of any other step or element or integer or group of elements or integers. Thus, in the context of this specification, the term “comprising” means “including principally, but not necessarily solely”. 
     The information provided herein and references cited are provided solely to assist the understanding of the reader, and do not constitute an admission that any of the references or information is prior art to the present invention. 
     The term “filament” or “filaments” means strands of extreme or indefinite length. The term “yarn” means a collection of numerous filaments which may or may not be entangled, twisted or laid together. 
     The term “texturing” means any operation of filaments which results in crimping, looping or otherwise modifying such filaments to increase cover, resilience, bulk or to provide a different surface texture or hand. It follows that a “bulked continuous filament” is a filament which has been subjected to one or more “texturing” operation(s). 
     By “biobased” is meant that the relevant material is made from substances derived from living matter. 
     A biobased fibre is herein defined as a fibre comprised of a polymer, or a blend or alloy of two or more polymers, in which one or more of said polymers has as at least one of the components making up the macromolecule thereof a substance ultimately derived wholly or partially from a biological, renewable, source. Such source may, for example, be a plant, or part of said plant such as roots, stems, leaves, flowers or seeds. 
     It will be understood that although the description of the carpet or carpet tile of the present invention has been given in terms of “layers”, that following processing the carpet tile is a bonded unitary integral structure in which the individual layers are not necessarily readily discernible or removable from one another. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, there is provided a floor covering including a primary backing layer having a fibrous face and an underside, wherein the fibrous face is formed from a bulked continuous filament yarn comprising a plurality of continuous filaments formed from a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer. 
     According to second aspect of the present invention, there is provided a method of making a floor covering comprising 
     tufting or implanting a bulked continuous filament yarn into a primary backing material, wherein the yarn comprises a plurality of continuous filaments formed from a multi-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer. 
     According to a third aspect of the present invention there is provided a floor covering comprising: 
     a primary backing having a fibrous face and an underside, wherein the fibrous face is formed from a bulked continuous filament yarn comprising a plurality of continuous filaments formed from a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer; 
     a cured precoat layer on the underside of the primary backing, and a backing layer fixed to the primary backing. 
     According to a fourth aspect of the present invention, there is provided a method of making a floor covering comprising: 
     tufting or implanting a bulked continuous filament yarn into a primary backing, wherein the yarn comprises a plurality of continuous filaments formed from a multi-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer; 
     precoating the underside of the primary backing layer by applying a precoating composition, applying a backing layer to the precoated primary backing layer, and 
     curing the precoating composition. 
     According to a fifth aspect of the present invention, there is provided a method of making a floor covering comprising: 
     coating a first layer of a thermoplastic resin plastisol on a support surface 
     optionally placing a dimensionally stable sheet material onto the top surface of the first layer and heating the layer to gel the layer and position the sheet material 
     optionally applying a second layer of a thermoplastic resin plastisol onto the gelled surface of the first layer; 
     tufting or implanting a bulked continuous filament yarn into a primary backing material, wherein the yarn comprises a plurality of continuous filaments formed from a multi-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer, 
     precoating the underside of the primary backing; 
     optionally coating a thermoplastic resin plastisol over the precoat layer; 
     layering the precoated primary backing onto the top surface of the plastisol of the first or second thermoplastic resin layer, 
     heating the floor covering so formed to fuse the thermoplastic layers into an integrally-fused backing layer, 
     cooling the flooring covering, and 
     optionally cutting the floor covering into a carpet tile. 
     According to a sixth aspect of the invention, there is provided a floor covering produced by the method of the fifth aspect. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to a floor covering including a primary backing layer having a fibrous face and an underside, wherein the fibrous face is formed from a bulked continuous filament yarn comprising a plurality of continuous filaments formed from a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer. 
     The present invention also relates to a method of making a floor covering comprising tufting or implanting a bulked continuous filament yarn into a primary backing material, wherein the yarn comprises a plurality of continuous filaments formed from a multi-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer. 
     There is also provided a floor covering comprising: 
     a primary backing having a fibrous face and an underside, wherein the fibrous face is formed from a bulked continuous filament yarn comprising a plurality of continuous filaments formed from a a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer; 
     a cured precoat layer on the underside of the primary backing, 
     and a backing layer fixed to the primary backing. 
     There is also provided a method of making a floor covering comprising: 
     tufting or implanting a bulked continuous filament yarn into a primary backing, wherein the yarn comprises a plurality of continuous filaments formed from a multi-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer; 
     precoating the underside of the primary backing layer by applying a precoating composition, 
     applying a backing layer to the precoated primary backing layer, and 
     curing the precoating composition. 
     There is also provided a method of making a floor covering comprising: 
     coating a first layer of a thermoplastic resin plastisol on a support surface 
     optionally placing a dimensionally stable sheet material onto the top surface of the first layer and heating the layer to gel the layer and position the sheet material 
     optionally applying a second layer of a thermoplastic resin plastisol onto the gelled surface of the first layer; 
     tufting or implanting a bulked continuous filament yarn into a primary backing material, wherein the yarn comprises a plurality of continuous filaments formed from a mufti-component fibre comprising a biobased polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer, 
     precoating the underside of the primary backing; 
     optionally coating a thermoplastic resin plastisol over the precoat layer; 
     layering the precoated primary backing onto the top surface of the plastisol of the first or second thermoplastic resin layer, 
     heating the floor covering so formed to fuse the thermoplastic layers into an integrally-fused backing layer, 
     cooling the flooring covering, and 
     optionally cutting the floor covering into a carpet tile. 
     There is also provided a floor covering produced by the methods. 
     Yarn 
     The biobased polyhexamethylene sebacamide polymer is suitably Ultramid Balance 6,10 available from BASF. This material is a polyamide 6,10 based on over 60% on sebacic acid derived from castor oil, which is itself a renewable resource obtained from the seeds of  Ricinus Communis . Suitably the polymer is 63% biobased. In one embodiment the biobased polyhexamethylene sebacamide polymer is blended with up to 80 wt % of at least one polymer compatible with the biobased polyhexamethylene sebacamide polymer. Suitable polymers for blending with the biobased polyhexamethylene sebacamide polymer include, but are not limited to nylon 6,6 or nylon 6,12. 
     The biobased polyhexamethylene sebacamide bulked continuous filament (BCF) yarn may be prepared by melt-spinning a polymer melt containing polyhexamethylene sebacamide polymer or a blend of a biobased polyhexamethylene sebacamide polymer together with up to 80 wt % of at least one other polymer compatible with the biobased polyhexamethylene sebacamide polymer to form at least one filament, passing the at least one filament to a drawing stage where the filament is drawn and lengthened, followed by texturing. 
     In one embodiment the process is conducted continuously. In another embodiment, the process is conducted as independent sequential operations. 
     Suitably the polymer melt may have a colourant dispersed therein prior to spinning, the colourant selected from at least one pigment and/or polymer soluble dyestuff. Alternatively, the resulting spun filaments, drawn filaments or bulked continuous yarn may be dyed. The at least one dispersed colourant may be any suitable pigment and may be chosen from organic and/or inorganic classes. In one embodiment the pigment is at least one pigment chosen from among: quinacridone magenta PR202, perylene red PR178, iron oxide red PR101, zinc iron yellow PY119, nickel azo yellow PY150, phthalocyanine green PG7, phthalocyanine blue PB15:1, titanium dioxide PW6 and carbon black PBlk7. The range of colourant to be added is typically bounded by a functional minimum below which appearance or lightfastness is unsuitable or a functional maximum at which chromatic saturation is achieved. While different for each of the aforenamed inorganic and organic colourants, a typical minimum of 0.05 wt % and a typical maximum of 2.5 wt % may be encountered. 
     Suitably the polymer melt includes at least one stabiliser. In this regard, the stabiliser may be any suitable stabiliser. In one embodiment the stabiliser is a mixture of cuprous iodide, potassium iodide and potassium bromide or other suitable stabiliser. Other suitable stabilisers included members of the benzatriazole or hindered amine families. In one embodiment cuprous cation may be included in a range between 10 and 100 ppm. In another embodiment halide anion may be included in the range between 100 and 5000 ppm. In another embodiment benzatriazole or hindered amines may be included in the range of 0.1 to 2.0 wt %. 
     Other optional additives which may be added to the polymeric melt include, but are not limited to, one or more of antistatics, antioxidants, antimicrobials, flameproofing agents, delustering agents, and lubricants. 
     Any or all of the above colourants, stabilisers and additives may be incorporated into the polymer melt by direct metering. Any or all of the above colourants, stabilisers and additives may be incorporated into the polymer melt in the form of a masterbatch, which term is well know to those skilled in the art. The carrier resin for use in the masterbatch is preferably the same polymer as that forming the continuous filaments but may also be any fibre-forming polymer fully miscible with the biobased polyhexamethylene sebacamide. Resins such as functionally modified polyesters and functionally modified or unmodified polyamides such as Nylon 6,6 and Nylon 6, 12 may also be used as carrier resin. Suitably, the colourants and/or stabilisers and/or additives are compounded into the carrier so that they are suitably dispersed. The colourants and/or stabilisers and/or additives and the prepared masterbatch are suitably dried to a moisture content of less than 0.2 wt %. 
     The speed and temperature of the process is suitably chosen to optimise the physical properties of the formed fibre whilst maximising throughput economics. 
     Suitably the spin speed of the polymeric melt is about 400 m/min-1500 m/min, for example about 1100 m/min. In one embodiment an extruder supplies molten polymeric material to a spinning head, the spinning head including spinnerettes having multiple small orifices through which the molten polymer material is extruded to form filaments which are then suitably passed to a quench chamber where a quench gas (such as air, steam or an inert gas such as nitrogen) is provided to cool and solidify the filaments. Suitably the quench gas is directed at the filament in a direction perpendicular to the filament travel. 
     Suitably the filaments are converged into a multifilament yarn prior to passing the yarn through the drawing stage. Suitably drawing is either over a contact point or around a roll. In this regard typically drawing is conducted on separated pairs of godet rolls or pairs (duos) operating at different rotational speeds. The filament(s) are drawn between the rolls at a desired draw ratio dependent on the speed differential, yarn temperature and yarn speed. The rolls are suitably heated to the same or similar temperature to elevate the filament temperature prior to texturing. In one embodiment the fibre is subjected to orientation through drawing and by allowing for crystalline growth and morphological alignment for example by allowing the fibre to dwell in repetitive transitory residence across at least one roller which may anisotropically orient the molecules in the filament thereby improving lateral strength. 
     Suitably the draw ratio is 2:1 to 4:1, more preferably the draw ratio is approximately 3 or below. Suitably, the filament is passed into the drawing stage at a speed of 1500 m/min or less, exiting at the described multiple speed thereof, whereby texturing may be practically accomplished. Suitably the texturing is conducted by means of a fluid jet texturing unit and the filament is fed into the unit at a rate faster than the rate at which the textured yarn is drawn off. Alternatively the texturing is conducted by means of mechanical crimping. Suitably the texturing increases the bulk of the fibre. The texturing imparted is suitably sufficient to induce dry heat shrinkage in excess of the linear shrinkage solely induced by orientation. Following texturing the yarn may be allowed to equilibrate naturally or in an accelerated manner by applying a moist heat environment. 
     At some suitable stage during the aforementioned processes, yarn is brought into contact with a finish applicator whereby a liquid finish is applied as desired. The finish may be applied at a single point or in multiple stages. 
     The textured or textured and finished yarn may be suitably combined with other yarns of the same or different type to form larger assemblies through air entanglement of multiple colours (such as on a Gilbos unit or one of suitable design) or through cable twisting, air twisting or braiding to form a finished yarn of the required design and aesthetic requirements. 
     The textured or textured and finished yarn may then be wound onto a package. 
     The above process steps may be conducted in a continuous sequence or may be conducted separately. Preferably the process steps are conducted in an uninterrupted sequence. 
     Typically, but without limitation; each yarn will have a denier of 15 to 21, a tenacity of 2.5 to 3.5 grams/denier and an elongation to break of greater than 30%. Denier is defined as the number of grams in 9,000 m length. 
     Primary Backing Layer 
     The primary backing may be a tufted fibrous layer or a fusion bonded material. When a tufted fibrous layer is used, it may be prepared by feeding the primary backing material to a conventional tufting machine which tufts fibres through interstices in the material. Tufting is typically performed such the resulting tufts protrude from the underside face with back stitches which hold the tufts in place on the topside of the material during processing 
     The primary backing is suitably formed from a woven or non-woven synthetic or non-synthetic fibre. Suitably a thermoplastic backing such as a woven polypropylene backing or a non-woven polyester, with a fibrous face or wear surface such as a tufted face, and a fibrous back surface, such as a loop or tufted surface where the carpet tile is tufted is used. A polyester such as Lutradur® is preferably used when making a PVC backed floor covering because it does not suffer too much from shrinkage due to heat during the gelling process thus minimizing the risk of tile uplift due to not enough drape. Other suitable backings include Nylon®, fibreglass, cotton, jute, rayon, paper, natural or synthetic rubbers, sponge or foam rubbers, polychloroprene, acrylonitrile-butadiene copolymers, ethylene-propylene-diene rubbers, petroleum resin, vinyl polymers (such as polyvinylchloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, copolymers or mixtures thereof), polybutene resin, polyisobutene-butadiene resins and copolymers and mixtures thereof. 
     The yarn may be used together with other fibrous materials and yarns employed in the floor coverings. Such fibrous materials and yarns may include synthetic, natural or a combination of synthetic and natural fibre, such as but not limited to other polyamides like nylon, olefins like polypropylene, wool and wool blends, cotton, acrylic, acrylic-nylon blends, polyester yarns and combinations and blends thereof. The yarns/fibrous materials may be used to form face or back yarn with the primary backing. 
     For a fusion bonded carpet tile, the fibrous material and yarns employed in the carpet tile are implanted into a material such as PVC or a hot melt adhesive which may be laminated to a substrate such as a woven or nonwoven material such as fibreglass, Nylon®, polypropylene or polyester. 
     The primary backing layer may be precoated with Latex or with another suitable precoating composition of the invention prior to applying a backing layer. Typically the precast is applied to cover the loop backs and to lock in the loops. 
     Latex 
     The latex may be an EVA latex or another vinyl polymer or acrylic-like polymer latex. For example, the latex may be a copolymer of acrylic and methacrylic acid and alkyl acrylates and esters (such as ethyl acrylate or methyl acrylate), acrylic-styrene copolymers, acrylonitrile-styrene copolymers, vinylidene chloride-acrylonitrile copolymers, and combinations thereof. Suitably the latex is non-halogenated. Other suitable latex materials which can be use include other vinyl, short-chain carboxylic acid copolymers, butadiene-acrylonitrile copolymer, styrene-butadiene, carboxylated styrene-butadiene, carboxylated styrene-butadiene-styrene. Urethane, PVC, acrylics or vinylidine chloride may also be used. 
     The precoating composition/latex may further comprise a thickener, an antibacterial, a fire retardant and/or a surfactant. A suitable antibacterial is zinc omadine—zinc2-pyridinethiol-1-oxide. A suitable fire retardant is aluminium hydroxide. A suitable surfactant is sodium lauryl sulphate. 
     In one embodiment a precoating composition is used comprising: at least one copolymer derived from an acrylic or methacrylic monomer and a styrenic monomer; at least one copolymer derived from an acrylic ester and a methacrylic ester, at least one thickener; and water. The copolymer derived from an acrylic or methacrylic monomer and a styrenic monomer is suitably an acrylate/styrene copolymer dispersion such as that supplied by BASF Corporation as Acronal® S 728 na. Acronal® S 728 na is a butyl acrylate/styrene copolymer dispersion and contains water in an amount of 49 to 51% w/w and a proprietory copolymer in an amount of about 49 to 51% w/w. The dispersion has a flash point greater than 300° F. (149° C.), a milky white with a faint ester-like odour, a pH of about 6.5 to 7.5, a boiling point of 212° C. (760 mmHg), a vapour pressure of 23 mbar (20° C.), a relative density of 1.04 (20° C.), a viscosity of 200 to 700 mPa·s and is miscible in water. This copolymer is traditionally used for coating in the paper industry but to date has not been used in the preparation of carpet tiles. Prior to addition to the precoating composition, the copolymer is suitably diluted to 25% solids with water. As indicated above the precoating composition may also contain a copolymer derived from an acrylic ester and a methacrylic ester. This copolymer facilitates the acrylic styrene sticking to thermoplastic materials such as PVC suitably used in the manufacture of the floor coverings. A suitable polymer is Acronal® AX 8281 AP available from BASF Aktiengesellschaft. This dispersion is white in colour with faint odour and a pH value of 7 to 8, a density of about 1.02 g/cm 3  at 20° C., a dynamic viscosity of 300 to 1500 mPa·s (23° C.) and a solids content of 48.5 to 51.5%. The polymeric dispersion is miscible in water. This acrylic addition raises the glass temperature in the aqueous solution. If used alone this acrylic resin is very brittle. Inclusion together with the acrylate/styrene copolymer allows the composition to stick/lock to the backing layer. Suitably about 20% dry weight of Acronal® is added (16% volume). The precoating composition suitably contains a thickener. Suitably the thickener is a thickener suitable for polymer dispersions, for example, an acrylic copolymer containing carboxyl groups. A suitable thickener is Latekoll® D available from BASF Aktiengesellschaft and is a low-viscosity, milky white anionic dispersion. Latekoll® D has a solids content (ISO 1625) of about 25±1%, a pH value of 2.3 to 3.3, a viscosity at 23° C., shear rate 250 s −1  of 2-10 mPa·s and a density at 20° C. of about 1.05 g/cm 3 . The thickener helps to prevent the precoating composition from wicking down holes in the primary backing layer. The thickener is suitably pre-diluted with water to form a homogeneous solution prior to the addition to the resins. 
     The precoating composition described above can be prepared by first mixing the copolymer derived from an acrylic or methacrylic monomer and a styrenic monomer and the copolymer derived from an acrylic ester and a methacrylic ester followed by addition of the thickener which has been pre-diluted with water, followed by addition of additional water. About 20% (of the dry weight of S728) of the AX8281 Acronal® is suitably added to the Acronal® S728 and suitably 1 to 2 wt % (up to 5%) of thickener added. It is important not to add too much thickener as strike through of the primary backing may occur. It is also important not add thickener to the base material followed by addition of water as the composition may overthicken locally. It is also important not to add the water/thickener solution too quickly to the Acronal® as this will result in curdling and an ineffective solution. The amount of AX8281 can range from 10% of the dry weight of S728 up to 40%, for example 20 to 35%. When present, the antibacterial, fire retardant and surfactant may be added at the end of the mixing cycle after the addition of water and thickener. 
     Application of the Latex/Precoating Composition to the Primary Backing Layer 
     The latex/precoating composition can be applied to the primary backing by roller coating, spraying or by foaming. The amount of latex/precoating used for a 850 g/m 2  carpet can be up to 100 g/m 2 . The latex/precoating composition serves to lock in the fibre on the back of the primary, such as a tufted back layer and acts as a barrier, separating the fibrous carpet from the underlying backing. The pre-coating is suitably heated to drive off sufficient water to provide a solid barrier and to allow for possible cross-linking. 
     The precoating layer has a thickness which is typically quite thin. Suitably the thickness is about 0.005 mm to 0.1 mm when dry. The thickness is suitably controlled by the use of spray nozzles and spray pressure. The precoating layer is suitably placed directly on and against the back surface of the loop or fibre containing primary backing and is applied in an amount to cover completely the loop backs and to lock in loops so that no mountains or valleys are evident. During processing the copolymers are cured and crosslinked. The resulting precoated product is very flexible. 
     Backing Layer 
     The floor covering may include a backing layer which imparts stability and free-laying properties to the floor covering. 
     Prior to applying the backing layer, it is possible to shear the carpet fibres it desired. Shearing is performed to cut the closed loop, tufted yarn on the face surface and to provide for the cut, tufted yarn to have the same general height as the height of the face wear surface fibres. 
     The backing layer may be formed from one or more layers of a thermoplastic polymer or other suitable backing material such as described above for the primary backing. In one embodiment the thermoplastic is a vinyl halide. A suitably vinyl halide is PVC (polyvinylchloride). Other suitable backings include bitumen, atactic polypropylene, polyolefin, ethylene vinyl acetate copolymer, thermoplastic elastomers, polyurethanes, PVC/Latex, Bitumen backed latex and polyurethane, polyamines, jute, urethane, polyvinylidine chloride, polyvinyl acetate, polyvinyl butyral, natural or synthetic rubber, polychloroprene. The backing layer may be in the form of a foam, sponge or solid. When in the form of a foam, the backing layer adds resilience and/or stability. 
     The backing layer can have a range of properties depending on the nature of polymers, plasticizers, stabilizers and fillers used. 
     Generally about 2.88 kg/m 2  of PVC is required to make carpet. When using the optional precoating composition of the present invention, whilst it is possible to still use 2.88 kg/m 2 , it is desired to reduce the amount of PVC to about 1 kg to 2 kg/m 2 , with 1.5 kg to 1.6 kg/m 2  being particularly suitable and still retain the flexibility. For bitumen tiles 2.8 kg/m 2  of bitumen paste is suitably added. 
     Backing Composition According to One Embodiment of the Invention 
     In one embodiment the backing is formed from a composition including a filler and a plasticizer together with a thermoplastic polymer such as PVC. In one embodiment of the invention, there is provided the use of recycled glass as filler in a PVC plastisol for the manufacture of a carpet tile. In one embodiment a composition for preparing a floor covering is used comprising: a thermoplastic resin; a plasticizer which is a mixture of an epoxidized soybean oil with an acetic acid ester of castor oil, and a filler. In another embodiment a composition for preparing a floor covering is used comprising: a thermoplastic resin; at least one plasticizer; and recycled glass. 
     The filler may be limestone or recycled glass or a combination of both recycled glass and limestone in any ratio of both. In a particularly preferred embodiment the filler is recycled glass. As the glass that may be used has a specific gravity of 2.0 to 2.5 and limestone a specific gravity of 2.7, less volume of glass is required than that of limestone. For example for 1357 kg of PVC paste, about 825 kg of limestone filler is required whereas only 611 kg of recycled glass is required. 
     The recycled glass fibres suitably have a particle size smaller than sand grains and are prepared by use of a ball mill so that they are round glass particles. They are typically an inert by-product (consumer waste) and do not absorb any of the plasticizer oil whereas limestone when used may absorb about 17 wt % plasticizer oil. 
     The recycled glass may be Enviro-glass available from Recycled Glass Mediums Australia Pty Ltd of 95 Wisemans Ferry Road Somersby NSW 2250, Australia and available in particle size ranges less than 0.106 mm up to 10 mm, for example 2.5 mm to 1.5 mm, 1.5 mm to 0.75 mm, 0.75 mm to 0.3 mm and 0.3 mm to 0.106 mm. 
     In one embodiment a 300 μm or less fine is used with preference for a fine having a majority of particles of less than 200 microns. 
     The product may be crushed glass—colourless, blue, mixed amber, mixed green, may be odourless, inorganic solid, ground and graded glass having a melting point above 800° C., a specific gravity of about 2.5 (this value is generic, the measured specific gravity of the product may be 2) and is typically insoluble in water. 
     The recycled glass may contain soda lime silica glass of the following chemical composition: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Na 2 O + K 2 O + Li 2 O 
                 12-15% 
               
               
                   
                 CaO + MgO 
                 10-13% 
               
               
                   
                 Al 2 O 3   
                 1-2% 
               
               
                   
                 Other oxides (except SiO 2 ) 
                 0-1% 
               
               
                   
                 Bound silica 
                 balance (contains 
               
               
                   
                   
                 no free silica) 
               
               
                   
                   
               
            
           
         
       
     
     About 40 to 70 wt % of the recycled glass may be used with respect to the total mix of plastisol. Suitably 50 to 61 wt % is used. 
     The plasticizer may be a standard phthalate plasticizer such as DINP, DEHP, DOP, PEG 100, or PEG 200 
     A particularly preferred plasticizer is the combination of epoxide soy bean oil and a castor oil derivative. In view of the fact that the epoxidised soy bean oil winters (i.e. at low temperatures the oil solidifies), it is difficult to get the required viscosity and consequently when used alone, suffers from plastic migration. Epoxide soy bean oil also does not have a long shelf life. The castor oil derivative results in good viscosity and avoids uptake and migration of the soy bean oil. A suitable composition includes 30% castor oil and 70% soybean oil. A suitable range of plasticizer is 40 to 20 wt % castor oil and 60 to 80 wt % soybean oil. A viscosity modifier such as an alcohol may be present as required to lower viscosity. A suitable viscosity modifier is ethanol. In one embodiment 5 to 10 wt % ethanol may be present. 
     The combination of epoxidised soy bean oil and a castor oil derivative acts synergistically. Suitably the combination is mixed at room temperature. 
     A suitable soy bean plasticizer is an epoxidised soya bean oil such as Lankroflex E2307 (ESBO) AG available from Swift and Company Limited, 372 Wellington Road, Mulgrave, Victoria 3170, Australia. Lankroflex E2307 is a low odour epoxy plasticizer containing pure epoxidised soya bean oil and having an oxirane oxygen content of 6.6% min, an iodine value of 2.5 max, a viscosity (30° C.) of 350 c-Poise max., an acid value of 0.4 KOH mg/g max., a moisture content of 0.1% max., a specific gravity (25° C.) of 0.992±0.01, a refractive index (25° C.) of 1.470±0.002 and a colour—120 APHA max. Lankroflex E2307 is a clear, yellow, oily liquid having a faint fatty odour and is a liquid at normal temperatures. The product has a boiling point above 200° C. at 100 kPa and a flashpoint of about 314° C., a specific gravity of 0.99 at 25° C., insoluble in water and a viscosity of 350 centipoise at 25° C. 
     The castor oil derivative is suitably an acetic acid ester of monoglycerides made from fully hydrogenated castor oil such as Grindsted® Soft-n-Safe/C available from Danisco Emulsifiers. The product has a degree of acetylation of about 0.9, an iodine value of 4 max, an acid value of 3 max, a saponification value of about 435 and is in the form of a clear liquid. The product contains octadecanoic acid, 12-(acetyloxy), bis(acetyloxy)propyl ester (about 85%) and octadecanoic acid, 2,3-bis(acetyloxy)propyl ester (about 10%). The product is a liquid at room temperature and is insoluble in water, decomposes above 300° C., and has a flash point above 100° C., a neutral odour, a density of 1.0030 g/ml at 20° C. and a vapour pressure of 1.05×10 −4  Torr at 123.6° C. 
     A preferred backing layer is formed from a composition comprising recycled glass and the soy bean oil/castor oil combination. This result is a more renewable and less fossil based product. In such a combination the composition may include up to about 60% thermoplastic (fossil origin) 
     Optional Additives and Layers 
     The primary backing and backing layer or latex/precoating composition may include any one or more of flame or fire retardants, inert fillers such as limestone or barytes, calcium oxide, carbon-black, antibacterials, surfactants, defoamers, thickeners, dispersing agents, elastomers, antioxidants, colourants, hardeners, plasticizers, UV/heat stabilizers, viscosity modifiers, cross-linking agents and/or tackifiers. 
     The use of a plasticizer in combination with the thermoplastic resin provides the required flexibility, durability and hardness. The presence of a heat stabilizer stabilizes the thermoplastic and prevents thermal decomposition, a UV stabilizer stabilizes the thermoplastic preventing decomposition as a result of exposure to UV light, calcium oxide ensures any moisture is removed from the mixing process, calcium carbonate (limestone) acts as filler, increasing the volume of the thermoplastic compound mix at reduced cost and a viscosity modifier maintains viscosity to ensure that the mix remains well mixed and in suspension (slowing the dropping out of solids). 
     The floor covering may include one or more woven or non-woven layers of glass, fibreglass, polyester, Nylon® or polypropylene such as tissue, mesh or fleece or scrim sheet materials or a combination thereof in the primary backing and backing layer. The scrim material may be employed adjacent to the primary backing or closely adjacent thereto. Glass fibre or tissue materials may be employed within the thermoplastic backing layer to impart dimensional stability and improve laying properties of the carpet tile. Cushion layers for example, formed of foam may also be included. 
     The underside of the backing layer may be provided with an adhesive with a shippable protective layer attached thereto, where, in use the protective layer is stripped off and the floor covering applied to the floor surface or applied with a pressure sensitive adhesive. 
     Application of the Backing Layer and Preparation of the Carpet Tile 
     The floor covering may be prepared in any suitable manner. 
     For example, a layer of thermoplastic may be applied/cast in a defined thickness onto the underside of the primary backing layer as a wet plastisol. The coated material is leveled with a doctor blade which levels and smooths the thermoplastic layer and forces the thermoplastic layer into engagement with any glass scrim and the primary backing. 
     Alternatively, the backing layer may be preformed on a releasable support such as a fluorocarbon, glass fibre endless belt, Teflon® coated fibreglass belt or stainless steel support sheet through casting. The precoated primary backing layer is then laid into the liquid backing layer. 
     Following application of the backing layer, the carpet is suitably heated to fuse/gel and cure the thermoplastic, cooled and optionally cut into carpet tile sections. Heating may be by use of a heater, radiant panels or heating elements. The heating cures the thermoplastic material and for a tufted carpet, thereby locks back stitches in place, the primary backing is thereby bonded to the backing layer by fibres of the primary backing being embedded in the backing layer. The carpet tile may be heated to a curing temperature within the range of 50° C. to 170° C., for example 90° C. to 160° C., 100° C. to 150° C. or 140° C. to 150° C. For example for PVC, the plasticizer melts and begins diffusing into particles at 50° C., gelation begins at about 50° C. and continues to about 130° C., at which point the particles swell, between 130° C. and 170° C. the gelation stage ends. At 91° C. the polymer flows into a continuous mass. 
     A suitable apparatus for finishing the carpet tile may be an apparatus including a heater having a chamber to operate at a desired temperature and through which the primary backing and backing layers pass to be heated to provide for plastic deformation of the backing layer, a pair of press rollers to which the primary backing, backing and any additional cushion layers are delivered, after the primary and backing layers have been heated by the heater, to apply a force thereto to cause the layers to bond, and a controller operatively associated with the heater, the controller being configured to maintain the temperature within the chamber to provide for heating of the backing layer so that the backing layer is relatively deformed by the rollers to bond the layers. 
     During gelling or after gelling the carpet may be passed under an embossing roller which embosses the back of the carpet with indentations, corrugations or the like to form a friction-increasing surface (resisting movement and maintaining position when placed in situ) and assists in consolidating the layers into a unitary product. The consolidated carpet material may then be severed by suitable cutting means into appropriate length sections (for example into squares). The laminated construction may be cooled for example to about 105° C. to allow removal of the construction from the support. The construction may then be passed through a heater and raised to about 100° C. prior to being engaged by an embossing roller that embosses the thermoplastic layer. 
     In one embodiment, the backing layer is formed of a layer of thermoplastic such as PVC, a fibreglass scrim and a second thermoplastic layer such as PVC. The first layer of thermoplastic bonds the primary backing to the fibreglass layer, the thickness of the layer suitably being controlled by a doctor blade. The fibreglass layer is to ensure dimensional stability of the carpet tile. The second layer of thermoplastic glues the layers above it and provides the final backing of the carpet tile. The thickness of this layer is also suitably controlled by a doctor blade. 
     The backing layer may be applied to the primary backing in a continuous fashion to produce an indeterminate length of material which may be subsequently cut as desired to form the carpet tile. 
     The thickness of each layer may vary depending on whether a solid layer or foam layer is used. For example, the first PVC layer range is dependant on the weight of the PVC backing i.e., 2.64 kg/m 2  would be two layers of 0.88 mm, 2 kg/m 2  would be two layers at 0.67 mm, while 1.5 kg/m 2  would be two layers at 0.5 mm. The overall carpet thickness may suitably be between about 4 and 12 mm, for example about 6 mm without foam backing and about 10 mm with foam backing. 
     Application 
     The resulting floor covering is suitable for use as a floor covering in home and/or commercial use. Pressure Sensitive adhesives may be required for installation and where floor tiles are prepared, the floor tiles can be replaced or rotated as desired. The floor covering has dimensional stability with substantially no curling, slipping, buckling, stretching or shrinkage and a low smoke emission. The floor covering is also stain resistant having a stain factor of 5 compared to previous nylons which have a stain factor of 2. 
     EXAMPLES 
     Example 1 
     Ultramid Balance® biobased nylon 6,10 resin available from BASF was dried, melt spun, drawn and air-jet textured to produce bulked continuous filament yarns of 1000 denier containing 60 filaments of tri-lobe cross-section. Four coloured yarns were produced via the addition during the melt spinning stage of formulated masterbatches containing various pigments. The four colours were dark brown (“Raisin”), light grey (“Hawk Grey”), medium grey (“Elephant”) and dark grey (“Seal”). The spin speed was 1100 m/min with a draw ratio of about 2.7:1. Finish oil was applied to the yarn during the spinning stage to give about 0.45% wt finish on yarn. The tenacities and elongations to break of the four yarns produced were as follows: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 Tenacity/ 
                 % Elongation 
               
               
                   
                 Yarn Colour 
                 g/denier 
                 at break 
               
               
                   
                   
               
             
            
               
                   
                 Raisin 
                 3.19 
                 76 
               
               
                   
                 Hawk Grey 
                 3.18 
                 81 
               
               
                   
                 Elephant 
                 3.15 
                 73 
               
               
                   
                 Seal 
                 3.04 
                 73 
               
               
                   
                   
               
            
           
         
       
     
     Example 2 
     A yarn comprising 90% wt of the 6,10 resin used in Example 1 and 10% of a nylon 6,6 resin with a sulfuric acid relative solution viscosity of 3.1 was produced using a similar process to Example 1. The nylon 6,10 and the nylon 6,6 were melt blended during the melt spinning stage. The bulked continuous yarn produced had a denier of 600 and consisted of 30 filaments of a tri-lobe cross-section. 
     Example 3 
     Carpet Tiles were prepared using the yarns prepared in Example 1 and 2. The resulting carpet tiles were found to pass the following property tests: Colourfastness, Tuflock, Lisson, Castor Chair, Dimensional Stability, Hexapod and Critical Heat Flux. 
     While the invention has been described with respect to a preferred embodiment, it will be understood that the invention is not limited to the preferred embodiment but is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.