Carpet Comprising A Propylene-Based Elastomer and Methods of Making the Same

Abstract

Provided are carpets comprising at least one propylene-based elastomer. The presence of the propylene-based elastomer provides the carpet with improved properties, including good tuft bind strength and tuft lock strength, and reliable construction.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Ser. No. 61/669,842 filed Jul. 10, 2012, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to carpets comprising propylene-based elastomers and methods of making the same.

BACKGROUND OF THE INVENTION

[0003] As illustrated in FIG. 1a, typical carpets may be laminated structures which include face yarn (which is also known as a fiber bundle), a primary backing layer having a face side and a back side, a precoat layer, a thermoplastic laminate layer, a reinforcement layer, and a thermoplastic cap layer. To form the face side of the carpet, yarn is typically tufted through the primary backing layer such that two ends are exposed at both sides of the primary backing layer, either left looped or cut on the face side. Generally, the primary backing layer is made of a woven or non-woven material.

[0004] The precoat layer is typically applied to the back side of the primary backing layer to affix the yarn to the primary backing layer. The extent or tenacity to which the yarn is affixed is referred to as tuft lock or tuft bind strength. Carpets with sufficient tuft bind strength and tuft lock strength exhibit reliable construction, and, as such, have long service lives. Also, the precoat layer may substantially penetrate the yarn (fiber bundle) exposed on the backside of the primary backing layer and may substantially consolidate individual fibers within the yarn.

[0005] Known precoat materials include latex, urethane, and vinyl systems, with latex systems being most popular. Styrene butadiene rubbers (SBR) and vinyl acetate ethylene (VAE) are the most common polymers used for latex adhesive backing materials. Typically, the latex backing system is heavily filled with an inorganic filler such as calcium carbonate or aluminum trihydrate and includes other ingredients such as antioxidants, antimicrobials, flame retardants, smoke suppressants, wetting agents, and froth aids.

[0006] The thermoplastic laminate layer is typically made of a filled thermoplastic polymer. The thermoplastic laminate layer is applied to the backside of the carpet onto the precoat layer, primarily to provide enhanced dimensional stability to the carpet structure as well as to provide more surface area for the application of direct glue-down adhesives. Thermoplastic compounds such as polyolefins have been suggested as additional backing materials for use in the thermoplastic laminate layer due in part to their low cost, good moisture stability, and no-cure requirements. Various methods are available for applying polyolefin backing materials, including roll coating, hot melt application, extrusion coating, and extruded film or sheet lamination. For example, to overcome the viscosity and recrystallization deficiencies of ordinary polyolefins and extrusion coating difficulties, ordinary polyolefins with sufficient flexibility can be applied between the primary backing and the thermoplastic cap layer as the thermoplastic laminate layer by extrusion coating or sheet lamination techniques to insure adequate yarn-to-backing adhesion.

[0007] A reinforcement layer can also be added between the laminate layer and the thermoplastic cap layer, to achieve enhanced dimensional stability.

[0008] The combination of tufted yarn and a primary backing layer without the application of a precoat layer is referred to in the carpet industry as raw tufted carpet or greige goods. Greige goods become finished tufted carpet with the application of a precoat layer and optionally a thermoplastic laminate layer to the back side of the primary backing layer. Finished tufted carpet can be prepared as broad-loomed carpet in rolls typically six or 12 feet (1.83 or 3.66 m) wide. Alternatively, carpets can be prepared as carpet tiles, typically 18 inches (about 45.7 cm) square or 24 inches (about 61.0 cm) square in the United States and 50 cm square elsewhere.

[0009] U.S. Pat. No. 7,741,397 describes a filled polymer composition comprising (i) an ethylene/a-olefin interpolymer, and (ii) a filler. The ethylene/a-olefin interpolymer is a block copolymer. The filled polymer composition can be used in automotive floorings, roofings, wire and cable coating applications.

[0010] U.S. Patent Publication Nos. 2007/0095453 and 2008/0280093 relate to carpets and method of making carpets. The carpet includes (a) a primary backing which has a face and a back surface, (b) a plurality of fibers attached to the primary backing and extending from the face of the primary backing and exposed at the back surface of the primary backing, (c) an adhesive backing, (d) an optional secondary backing adjacent to the adhesive backing, and (e) at least one homogeneously branched linear ethylene polymer. The method includes extrusion coating at least one homogeneously branched linear ethylene polymer onto the back surface of a primary backing to provide an adhesive backing.

[0011] Although there are various systems known in the art of carpet backings, there remains a need for a carpet backing system which provides adequate tuft bind strength and tuft lock strength, reliable construction and enhanced flexibility. Preferably such a carpet backing system could be used to replace latex backing systems. Applicants have found that the above desirable properties can be surprisingly achieved by using at least one layer comprising propylene-based elastomers. In some embodiments, a layer comprising propylene-based elastomers can act as a substitute for both the current precoat layer, mainly comprising latex, and the thermoplastic laminate layer. This can be advantageous in cases where the carpet surface becomes wet, as the absence of latex avoids latex decomposition which can significantly decrease the performance for the carpet. Furthermore, the layer comprising propylene-based elastomers may be filled with fillers, which can also lead to additional advantages such as improved flame retardant properties and reduced cost for carpet application.

SUMMARY OF THE INVENTION

[0012] Provided are carpets comprising a propylene-based elastomer, and methods of making the same. In accordance with one embodiment of the present invention, a carpet comprises: (a) a primary backing layer having a face side and a back side; (b) a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; and (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

[0013] In another embodiment, the present invention relates to a method for making a carpet comprising the steps of: (a) providing a primary backing layer having a face side and a back side, with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; (b) applying a second layer to the back side of the primary backing layer, wherein the layer comprises at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; and (c) forming a carpet, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1a exemplifies a conventional laminated structure for a tufted carpet tile.

[0015] FIG. 1b exemplifies an embodiment of the inventive laminated structure for a tufted carpet tile.

[0016] FIG. 2 depicts the resulting appearances on the back and front sides of Sample 1 and Sample 2 after a Velcro roller test. In particular, FIGS. 2a and 2b illustrate the back and front, respectively, of Sample 1 of the Examples after a Velcro roller test. FIGS. 2c and 2d illustrate the back and front, respectively, of Sample 2 of the Examples after a Velcro roller test.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0017] Various specific embodiments, versions of the present invention will now be described, including preferred embodiments and definitions that are adopted herein. While the following detailed description gives specific preferred embodiments, those skilled in the art will appreciate that these embodiments are exemplary only, and that the present invention can be practiced in other ways. Any reference to the "invention" may refer to one or more, but not necessarily all, of the present inventions defined by the claims. The use of headings is for purposes of convenience only and does not limit the scope of the present invention.

[0018] As used herein, a "polymer" may be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc.

[0019] As used herein, when a polymer is referred to as comprising a monomer, the monomer is present in the polymer in the polymerized form of the monomer or in the derivative form of the monomer.

[0020] As used herein, when a polymer composition or blend is said to comprise a certain percentage, wt %, of a monomer, that percentage of monomer is based on the total amount of monomer units of all the polymer components of the polymer composition or blend.

[0021] As used herein, "elastomer" or "elastomeric composition" refers to any polymer or composition of polymers (such as blends of polymers) consistent with the ASTM D1566 definition. Elastomer includes mixed blends of polymers such as melt mixing and/or reactor blends of polymers. The terms may be used interchangeably with the term "rubber(s)."

[0022] A "polyolefin" is a polymer comprising at least 50 wt % of one or more olefin monomers. Preferably, a polyolefin comprises at least 60 wt %, or at least 70 wt %, or at least is 80 w t%, or at least 90 wt %, or at least 95 wt %, or 100 wt %, of one or more olefin monomers.

[0023] Preferably, a polyolefin comprises 1-olefins, having carbon numbers of 2 to 20, or 2 to 16, or 2 to 10, or 2 to 8, or 2 to 6.

[0024] As used herein, "primary backing" layer, "second" layer, "third" layer, and "middle" layer are merely identifiers used for convenience, and shall not be construed as limitation on individual layers, their relative positions, or the laminated structure, unless otherwise specified.

[0025] As used herein, when a layer is referred to as "substantially" locking the plurality of fibers extending from the back side of the primary backing layer in, it means that at least about 90%, at least about 92%, at least about 94%, at least about 96%, or at least about 98% of the fibers are held in place after being rolled over by a Velcro type tool for about 20 times in a Velcro roller test. Preferably, no fuzzing is visible to the naked eye.

[0026] As used herein, "carpet" also includes carpet tiles and portions of a carpet.

[0027] The present invention relates to a carpet comprising a propylene-based elastomer, and methods of making the same. In one embodiment, a carpet comprises: (a) a primary backing layer having a face side and a back side; (b) a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; and (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

Propylene-based elastomer

[0028] The carpets described herein comprise a propylene-based elastomer. The propylene-based elastomer may be a copolymer of propylene-derived units and units derived from at least one of ethylene or a C.sub.4-10 alpha-olefin. The propylene-based elastomer may contain at least about 60 wt % propylene-derived units based on the weight of the propylene-based elastomer. The propylene-based elastomer may have limited crystallinity due to adjacent isotactic propylene units and a melting point as described herein. The crystallinity and the melting point of the propylene-based elastomer can be reduced compared to highly isotactic polypropylene by the introduction of errors in the insertion of propylene. The propylene-based elastomer is generally devoid of any substantial intermolecular heterogeneity in tacticity and comonomer composition, and also generally devoid of any substantial heterogeneity in intramolecular composition distribution.

[0029] The amount of propylene-derived units present in the propylene-based elastomer may range from an upper limit of about 95 wt %, about 94 wt %, about 92 wt %, about 90 wt %, or about 85 wt %, to a lower limit of about 60 wt %, about 65 wt %, about 70 wt %, about 75 wt %, about 80 wt %, about 84 wt %, or about 85 wt % of the propylene-based elastomer.

[0030] The units, or comonomers, derived from at least one of ethylene or a C.sub.4-10 alpha-olefin may be present in an amount of about 1 to about 35 wt %, or about 5 to about 35 wt %, or about 7 to about 32 wt %, or about 8 to about 25 wt %, or about 8 to about 20 wt %, or about 8 to about 18 wt %, based on the weight of the propylene-based elastomer.

[0031] In preferred embodiments, the comonomer is ethylene, 1-hexene, or 1-octene. In some embodiments, the propylene-based elastomer comprises ethylene-derived units or consists essentially of units derived from propylene and ethylene, i.e., the propylene-based elastomer does not contain any other comonomer in an amount other than that typically present as impurities in the ethylene and/or propylene feedstreams used during polymerization, or in an amount that would materially affect the heat of fusion, melting point, crystallinity, or MI of the propylene-based elastomer, or any other comonomer intentionally added to the polymerization process. In such embodiments, the propylene-based elastomer may comprise about 5 to about 25 wt %, or about 6 to about 22 wt %, or about 7 to about 20 wt %, or about 8 to about 17 wt %, or about 9 to 16 wt % ethylene-derived units based on the weight of the propylene-based elastomer.

[0032] The propylene-based elastomer may comprise more than one comonomer. Preferred embodiments of a propylene-based elastomer having more than one comonomer include propylene-ethylene-octene, propylene-ethylene-hexene, and propylene-ethylene-butene polymers. In embodiments where more than one comonomer derived from at least one of ethylene or a C.sub.4-10 alpha-olefin is present, the amount of one comonomer may be less than about 5 wt % of the propylene-based elastomer, but the combined amount of comonomers of the propylene-based elastomer is about 5 wt % or greater.

[0033] In some embodiments, the propylene-based elastomer may further comprise a diene. The optional diene may be any hydrocarbon structure having at least two unsaturated bonds wherein at least one of the unsaturated bonds is readily incorporated into a polymer. For example, the optional diene may be selected from straight chain acyclic olefins, such as 1,4-hexadiene and 1,6-octadiene; branched chain acyclic olefins, such as 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, and 3,7-dimethyl-1,7-octadiene; single ring alicyclic olefins, such as 1,4-cyclohexadiene, 1,5-cyclooctadiene, and 1,7-cyclododecadiene; multi-ring alicyclic fused and bridged ring olefins, such as tetrahydroindene, norbornadiene, methyl-tetrahydroindene, dicyclopentadiene, bicyclo-(2.2.1)-hepta-2,5-diene, norbornadiene, alkenyl norbornenes, alkylidene norbornenes, e.g., ethylidiene norbornene ("ENB"), cycloalkenyl norbornenes, and cycloalkyliene norbornenes (such as 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-propenyl-2-norbornene, 5-isopropylidene-2-norbomene, 5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene); and cycloalkenyl-substituted alkenes, such as vinyl cyclohexene, allyl cyclohexene, vinyl cyclooctene, 4-vinyl cyclohexene, allyl cyclodecene, vinyl cyclododecene, and tetracyclo (A-11,12)-5,8-dodecene. The amount of diene-derived units present in the propylene-based elastomer may range from an upper limit of about 15%, about 10%, about 7%, about 5%, about 4.5%, about 3%, about 2.5%, or about 1.5%, to a lower limit of about 0%, about 0.1%, about 0.2%, about 0.3%, about 0.5%, or about 1%, based on the total weight of the propylene-based elastomer. In some embodiments, the propylene-based elastomer does not contain any diene-derived units.

[0034] The propylene-based elastomer may have a triad tacticity of three propylene units, as measured by 13C NMR, of at least about 75%, at least about 80%, at least about 82%, at least about 85%, or at least about 90%. Preferably, the propylene-based elastomer has a triad tacticity of about 50 to about 99%, about 60 to about 99%, about 75 to about 99%, or about 80 to about 99%. In some embodiments, the propylene-based elastomer may have a triad tacticity of about 60 to 97%.

[0035] The propylene-based elastomer may have a heat of fusion ("H.sub.f"), as determined by DSC, of about 75 J/g or less, about 70 J/g or less, about 50 J/g or less, or about 45 J/g or less, or about 35 J/g or less. The propylene-based elastomer may have a lower limit H.sub.f of about 0.5 J/g, about 1 J/g, or about 5 J/g. For example, the H.sub.f value may be anywhere from 1.0, 1.5, 3.0, 4.0, 6.0, or 7.0 J/g, to 30, 35, 40, 50, 60, 70, or 75 J/g.

[0036] The propylene-based elastomer may have a percent crystallinity, as determined according to the DSC procedure described herein, of about 2 to about 65%, about 0.5 to about 40%, about 1 to about 30%, or about 5 to about 35%, of the crystallinity of isotactic polypropylene. The thermal energy for the highest order of propylene (i.e., 100% crystallinity) is estimated at 189 J/g. In some embodiments, the copolymer has crystallinity less than 40%, or in the range of about 0.25 to about 25%, or about 0.5 to about 22%, of isotactic polypropylene. Embodiments of the propylene-based elastomer may have a tacticity index m/r from a lower limit of about 4 or about 6 to an upper limit of about 8 or about 10 or about 12. In some embodiments, the propylene-based elastomer has an isotacticity index greater than 0%, or within the range having an upper limit of about 50% or about 25%, and a lower limit of about 3% or about 10%.

[0037] The propylene-based elastomer may have a single peak melting transition as determined by DSC. In one embodiment, the copolymer has a primary peak transition of about 90.degree. C. or less, with a broad end-of-melt transition of about 110.degree. C. or greater. The peak "melting point" ("T.sub.m") is defined as the temperature of the greatest heat absorption within the range of melting of the sample. However, the copolymer may show secondary melting peaks adjacent to the principal peak, and/or at the end-of-melt transition. For the purposes of this disclosure, such secondary melting peaks are considered together as a single melting point, with the highest of these peaks being considered the Tm of the propylene-based elastomer. The propylene-based elastomer may have a T.sub.m of about 105.degree. C. or less, about 100.degree. C. or less, about 90.degree. C. or less, about 80.degree. C. or less, or about 70.degree. C. or less. In some embodiments, the propylene-based elastomer has a Tm of about 25 to about 105.degree. C., about 60 to about 105.degree. C., about 70 to about 105.degree. C., or about 90 to about 105.degree. C.

[0038] The propylene-based elastomer may have a density of about 0.850 to about 0.920 g/cm3, or about 0.860 to about 0.880 g/cm3, at room temperature as measured per ASTM D1505.

[0039] The propylene-based elastomer may have a MI, as measured per ASTM D1238, 2.16 kg at 190.degree. C., of at least about 1 g/10 min. In some embodiments, the propylene-based elastomer may have an MI of from a lower limit of about 25 g/10 min, about 40 g/10 min, about 60 g/10 min, about 80 g/10 min, about 100 g/10 min, about 150 g/10 min, about 200 g/10 min, or about 300 g/10 min, to an upper limit of about 15,000 g/10 min, 10,000 g/10 min, 5,000 g/10 min, 2,000 g/10 min, about 1500 g/10 min, about 1200 g/10 min, about 1000 g/10 min, about 800 g/10 min, about 600 g/10 min, about 500 g/10 min, or about 400 g/10 min.

[0040] The propylene-based elastomer may have an Elongation at Break of less than about 2000%, less than about 1000%, or less than about 900%, as measured per ASTM D412.

[0041] The propylene-based elastomer may have a weight average molecular weight (Mw) of about 5,000 to about 5,000,000 g/mole, about 10,000 to about 1,000,000 g/mole, about 20,000 to about 750,000 g/mole, about 30,000 to about 400,000 g/mole.

[0042] The propylene-based elastomer may have a number average molecular weight (Mn) of about 2,500 to about 250,000 g/mole, about 10,000 to about 250,000 g/mole, or about 25,000 to about 200,000 g/mole.

[0043] The propylene-based elastomer may have a z-average molecular weight (Mz) of about 10,000 to about 7,000,000 g/mole, about 80,000 to about 700,000 g/mole, or about 100,000 to about 500,000 g/mole.

[0044] The propylene-based elastomer may have a molecular weight distribution ("MWD") of about 1.5 to about 20, or about 1.5 to about 15, preferably about 1.5 to about 5, and more preferably about 1.8 to about 3, and most preferably about 1.8 to about 2.5.

[0045] The comonomer content may be adjusted so that the propylene-based elastomer has a heat of fusion of less than about 75 J/g, a melting point of about 105.degree. C. or less, and a crystallinity of about 2% to about 65% of the crystallinity of isotactic polypropylene, and a melt index (MI) of at least about 25 g/10 min. The propylene-based elastomer may comprise copolymers prepared according to the procedures described in WO 02/36651, U.S. Patent No. 6,992,158, and/or WO 00/01745, the contents of which are incorporated herein by reference. Preferred methods for producing the propylene-based elastomer may be found in U.S. Pat. Nos. 7,232,871 and 6,881,800, the contents of which are incorporated herein by reference. The invention is not limited by any particular polymerization method for preparing the propylene-based elastomer, and the polymerization processes are not limited by any particular type of reaction vessel.

[0046] Suitable propylene-based elastomers may be available commercially under the trade names VISTAMAXX.TM. (ExxonMobil Chemical Company, Tex., USA), VERSIFY.TM. (The Dow Chemical Company, Mich., USA), certain grades of TAFMER.TM. XM or NOTIO.TM. (Mitsui Company, Japan), and certain grades of SOFTEL.TM. (Basell Polyolefins of the Netherlands). The particular grade(s) of commercially available propylene-based elastomer suitable for use in the invention can be readily determined using methods commonly known in the art.

Thermoplastic polyolefin

[0047] In some embodiments of the present invention, the primary backing layer, middle, and/or third layer of the carpet may comprise at least one thermoplastic polyolefin. The thermoplastic polyolefin in the third layer and the middle layer may be the same as or different from the propylene-based elastomer in the primary backing layer. Depending on the type and amount of the thermoplastic polyolefin, the final structure comprising the thermoplastic olefin may have thermoplastic, elastomeric, or thermoplastic elastomeric properties.

[0048] Thermoplastic polyolefins suitable for use in the carpet include thermoplastic, crystalline polyolefin homopolymers and copolymers. They are desirably prepared from monoolefin monomers having 2 to 7 carbon atoms, such as ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1 -pentene, 4-methyl-1-pentene, 5-methyl-1-hexene, mixtures thereof and copolymers thereof with (meth)acrylates and/or vinyl acetates. Preferred, however, are monomers having 3 to 6 carbon atoms, with propylene being most preferred.

[0049] In some embodiments the thermoplastic polyolefin may be a functionalized ethylene copolymer, preferably a maleic anhydride functionalized elastomeric ethylene copolymer, e.g., those commercially available under the trade name EXXELOR.TM. (ExxonMobil Chemical Company, Tex., USA).

[0050] As used in the specification and claims the term polypropylene includes homopolymers of propylene as well as copolymers comprising propylene. Copolymers comprising propylene refer to reactor copolymers of polypropylene (reacted blends) and random copolymers containing more than 94% by weight of propylene, the remainder being selected from the comonomers (other than propylene) mentioned above, preferably ethylene. Typically, the random copolymers of polypropylene with ethylene contain about 1 to about 6 wt %, preferably less than about 6 wt % of ethylene and/or about 1 to about 30 wt % of an alpha-olefin comonomer of 4 to 16 carbon atoms, and mixtures thereof The polypropylene can be highly crystalline isotactic or syndiotactic polypropylene. Commercially available polyolefins may be used in the practice of the present invention. Further polyolefins which can be used in terms of the invention are high, low, linear-low, very low-density polyethylenes and copolymers of ethylene with (meth)acrylates and/or vinyl acetates.

[0051] The thermoplastic polyolefins mentioned above can be made by conventional Ziegler-Natta catalyst systems or by single-site catalyst systems, including polyolefins such as polyethylene copolymers obtained by metallocene catalysis with butene, hexene or octene as the comonomer. The amount of comonomer present in a polyethylene copolymer determines the density of the copolymer. Metallocene polymers or plastomers refer to polymers or plastomers prepared using a class of well-known highly active olefin catalysts known as metallocenes. These catalysts, particularly those based on group IV B transition metals such as zirconium, titanium and hafnium, show high activity in ethylene polymerization. The metallocene catalysts are also flexible in that, by manipulation of catalyst composition and reaction conditions, they can provide polyolefins with controllable molecular weights, as low as about 200 up to about 1 million or higher, and molecular weight distribution, from extremely narrow to broad. Metallocene catalysts are useful in making controlled ultra-uniform and super random specialty copolymers. For example, if a lower density ethylene copolymer is made with a metallocene catalyst, such as very low density polyethylene (VLDPE), an ultra-uniform and super random copolymerization will occur, as contrasted with the polymer produced by copolymerization using a conventional Ziegler catalyst.

Filler

[0052] One or more layers of the carpet of the present invention may include a filler. In another embodiment, the second and/or third layers may include a filler. The classes of materials described herein that are useful as fillers can be utilized alone or admixed to obtain desired properties. In any of the embodiments, the filler may be present at up to about 80 wt %, preferably up to about 70 wt %, more preferably from about 60 wt % to about 65 wt %, based on the total weight of the layer.

[0053] Desirable fillers can be organic fillers and/or inorganic fillers. Useful fillers include such materials as carbon black, fly ash, graphite, cellulose, starch, flour, wood flour, and polymeric fibers like polyester-based, polyamide-based materials, etc. Preferred examples of fillers are calcium carbonate, aluminum trihydrate, talc, glass fibers, marble dust, cement dust, clay, feldspar, silica or glass, fumed silica, alumina, magnesium oxide, antimony oxide, zinc oxide, barium sulfate, calcium sulfate, aluminum silicate, calcium silicate, titanium dioxide, titanates, clay, nanoclay, organo-modified clay or nanoclay, glass microspheres and chalk. In some embodiments, the one or more layers of the carpet comprise a filler for improving the flame retardant properties of the carpet, such as aluminum trihydrate or calcium carbonate.

Carpet Layers

[0054] The carpets described herein have a primary backing layer having a face side and a back side with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer. A second layer is attached to the back side of the primary backing layer and locks in the plurality of fibers extending from the back side of the primary backing layer. In some embodiments, the carpet further comprises a third layer on the back side of the second layer opposite to the primary backing layer. In some embodiments, the carpet further comprises a reinforcement layer between the second layer and the third layer.

[0055] In some embodiments, the primary backing layer may comprise a thermoplastic polyolefin as described above. In other embodiments, the primary backing layer may be a nonwoven layer comprising bicomponent filaments. For example, the primary backing layer may comprise bicomponent continuous filaments having a polyethylene terephthalate core and a polyamide or polypropylene skin/sheath.

[0056] The face yarn may comprise various materials including, but not limited to, polypropylene, nylon, wool, cotton, acrylic, polyester and polyethylene terephthalate (PET).

[0057] The second layer of the carpet may include one or more different propylene-based elastomers as described above. For example, the second layer of the carpet may comprise at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g.

[0058] In some embodiments, the second layer may comprise more than one propylene-based elastomers each having one or more different properties such as, for example, different comonomer or comonomer content. Such combinations of various propylene-based elastomers are all within the scope of the invention.

[0059] In some embodiment, the third layer also comprises one or more propylene-based elastomers. In other embodiments, the third layer comprises at least one thermoplastic polyolefin. It is preferred that the third layer is made from a thermoplastic polyolefin to facilitate recycling, which can be the same as or different from the propylene-based elastomer in the second layer.

[0060] In some embodiments, the reinforcement layer may comprise at least one of thermoplastic fabrics and fiberglass.

[0061] In some embodiments, the carpet may comprise a primary backing layer having a face side and a back side with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer. A second layer that acts as a precoat layer may be attached to the back side of the primary backing layer and lock in the plurality of fibers extending from the back side of the primary backing layer. In such embodiments, the second layer may comprise latex. The carpet further comprises a middle layer on the back side of the second layer opposite to the primary backing layer and a third layer on the back side of the middle layer opposite to the second layer. The middle and third layers may comprise propylene-based elastomers as described herein. The carpet may further comprise a reinforcement layer between the middle layer and the third layer.

[0062] In some embodiments, the carpet may comprise a primary backing layer having a face side and a back side with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer. A second layer may be attached to the back side of the primary backing layer and lock in the plurality of fibers extending from the back side of the primary backing layer. In such embodiments, the second layer may comprise a propylene-based elastomer as described herein. The carpet further comprises a middle layer on the back side of the second layer opposite to the primary backing layer and a third layer on the back side of the middle layer opposite to the second layer. The middle and third layers may comprise propylene-based elastomers as described herein. The carpet may further comprise a reinforcement layer between the middle layer and the third layer.

[0063] In some embodiments, the carpet may comprise a primary backing layer having a face side and a back side with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer. A second layer attached to the back side of the primary backing layer and lock in the plurality of fibers extending from the back side of the primary backing layer. The carpet further comprises a third layer on the back side of the second layer opposite to the second layer. The third layer may comprise propylene-based elastomers as described herein. The carpet may further comprise a reinforcement layer between the second layer and the third layer. In such embodiments, the carpet may not comprise a middle layer.

[0064] In some embodiments, compared to the conventional carpet comprising a latex precoat layer present in an amount of 18-28 oz /yd.sup.2 (about 612-952 g/m.sup.2 of latex), the inventive second or middle layer containing a propylene-based elastomer may substantially eliminate the need of using latex in the carpet. For example, in such embodiments the carpet may comprise a trace amount of no more than 150 g/m.sup.2 of latex, or no more than 100 g/m.sup.2 of latex, or no more than 50 g/m.sup.2 of latex, or no more than 20 g/m.sup.2 of latex, or 0 g/m.sup.2 of latex.

Methods For Making the Carpet

[0065] Also provided are methods for making the carpet. The method for making a carpet may comprise the steps of: (a) providing a primary backing layer having a face side and a back side, with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; (b) applying a second layer to the back side of the primary backing layer, wherein the layer comprises at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; and (c) forming a carpet, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

[0066] Any conventional tufting or needle-punching apparatus and stitch patterns can be used. Tufted yarn loops may be left uncut to produce a loop pile; cut to make cut pile; or cut, partially cut and uncut to make a face texture known as tip sheared.

[0067] After the yarn is tufted or needle-punched into the primary backing layer, the greige good is typically rolled up with the back side of the primary backing layer facing outward and held until it is transferred to the backing line.

[0068] In a preferred embodiment, the greige good is scoured or washed before it has a second layer extruded thereon. In particular, yarn that is tufted or needle-punched to make carpet often has varying quantities of processing materials, most commonly oily or waxy chemicals, known as spin-finish chemicals, remaining thereon from the yarn manufacturing processes. It has been found to be preferable to remove or displace all or substantially all of these processing materials prior to extruding the second layer comprising the propylene-based elastomer onto the back surface of the primary backing layer.

[0069] The second layer can be applied by various methods, including extrusion coating and sheet lamination, with the preferred method involving the use of an extruded sheet of a propylene-based elastomer, onto which a third layer is extrusion coated or sheet laminated. In particular, a molten propylene-based elastomer is preferably extruded through a die so as to make a sheet which is as wide as the carpet. The molten, extruded sheet is applied to the back side of the primary carpet backing layer. Since the sheet is molten, the sheet will conform to the shape of the loops of yarn and further serve to fix the loops in the primary backing.

[0070] Extrusion coating configurations include a monolayer T-type die, single-lip die coextrusion coating, dual-lip die coextrusion coating, and multiple stage extrusion coating.

[0071] The line speed of the extrusion process will depend on factors such as the particular polymer being extruded, the exact equipment being used, and the weight of polymer being applied. The extrusion coating melt temperature principally depends on the particular polymer being extruded.

[0072] Since the second layer may be relied on to encapsulate and lock the yarn in place, this layer may have a MI high enough (melt viscosity low enough), for example, of from a lower limit of about 25 g/10 min, about 40 g/10 min, about 60 g/10 min, about 80 g/10 min, about 100 g/10 min, about 150 g/10 min, about 200 g/10 min, or about 300 g/10 min, to an upper limit of about 15000g/10 min, about 1500 g/10 min, about 1200 g/10 min, about 1000 g/10 min, about 800 g/10 min, about 600 g/10 min, about 500 g/10 min, or about 400 g/10 min, to promote encapsulation and locking of the yarn.

[0073] Auxiliary equipment such as a pre-heater can be used. In particular, a heater, such as a convection oven or infrared panels can be used to heat the back of the greige good before the second layer is extruded thereon. In doing so, it has been found that the encapsulation is and locking of the yarn bundles can be enhanced.

[0074] The extruded polymer(s) can either be used neat, or can have one or more additive included. A preferred additive is an inorganic filler. Examples of such fillers include, but are not limited to, calcium carbonate, aluminum trihydrate, talc, and barite. Inorganic mineral fillers can improve yarn encapsulation and locking which in turn improves the performance of the tuft bind strength and tuft lock strength of extrusion coated carpet samples. Preferably, filler is added at a level of up to about 80 wt %, preferably up to about 70 wt %, more preferably from about 60 wt % to about 65 wt %, based on the total weight of the extruded layer. For the second layer of the present invention, fillers which may serve as flame retardant are preferred, such as aluminum trihydrate or calcium carbonate.

[0075] Other additives that may also be included include antioxidants such as sterically hindered phenols, sterically hindered amines and phospites may be used. Other possible additives include antiblock additives, pigments and colorants, anti-static agents, tackifiers (such as aromatic modified aliphatic hydrocarbon resins, e.g., those commercially available under the trade name ESCOREZ.TM. (ExxonMobil Chemical Company, Tex., USA)), compatibilizers (functionalized ethylene copolymers, preferably maleic anhydride functionalized elastomeric ethylene copolymers, e.g., those commercially available under the trade name EXXELOR.TM. (ExxonMobil Chemical Company, Tex., USA)), processing aids (such as stearic acid), antimicrobial agents (such as quaternary ammonium salts), chill roll release additives (such as fatty acid amides) and other aids (such as metallocene-based homopolymers, e.g., those commercially available under the trade name ACHIEVE.TM. (ExxonMobil Chemical Company, Tex., USA)).

[0076] As noted above, the carpet may also include a third layer. The third layer can be laminated in a later step by reheating and/or remelting at least the outermost portion of the extruded layer or by a coextrusion coating technique using at least two dedicated extruders.

[0077] The extrusion backed carpet construction and the methods described herein are particularly suited for making carpet tile. In one embodiment, yarn is tufted into a primary backing layer, so as to leave a carpet pile face on top of the primary backing layer and back stitches below the primary backing. Applied to the back of the primary backing layer and the back stitches is a second layer comprising a propylene-based elastomer. Preferably, the second layer further comprises a filler. The filler can be aluminum trihydrate with a loading of about 60 wt %, based on the total weight of the extruded layer.

[0078] In preferred embodiments, the carpet includes no more than 150 g/m.sup.2 of latex, no more than 100 g/m.sup.2 of latex, no more than 50 g/m.sup.2 of latex, no more than 20 g/m.sup.2 of latex, or 0 g/m.sup.2 of latex.

[0079] When making carpet tile, it is preferable to embed a reinforcement layer between the second and third layers. An important property of carpet tile is dimensional stability, i.e., the ability of the tile to maintain its size and flatness over time. The inclusion of this layer of reinforcing material has been found to enhance the dimensional stability of carpet tile made according to this preferred embodiment. Suitable materials for the reinforcement layer include dimensionally and thermally stable fabrics such as fiberglass, as well as thermoplastic fabrics (e.g., polypropylene, nylon and polyester). Optionally, there is a middle layer present between the second layer and the reinforcement layer, preferably, also made from a thermoplastic polyolefin, which can be the same as or different from the propylene-based elastomer in the second layer.

[0080] Carpet tile is typically made by producing a length of backed carpet and then cutting the carpet into the appropriate sized squares. The most common sizes include 18 inches (45.7 cm) square, 24 inches (about 61.0 cm) square, or 50 cm square.

[0081] The carpets described herein may have improved properties, including tuft bind strength and tuft lock strength, and reliable construction, by substantially locking face yarn in place with use of a propylene-based elastomer, typically in a single layer replacing both the current precoat primarily comprising latex and the thermoplastic laminate layer. It can also be expected that the carpet, preferably without latex, may show such improved yarn adhesion when exposed to water, for there would be little latex decomposition leading to loss of tuft bind and tuft lock as it occurs in the conventional carpet. Meanwhile, the propylene-based elastomer, if filled, may further impart enhanced flame retardant properties of the carpet. Even when highly filled, the propylene-based elastomer is still able to remain flexible and durable, enhance adhesion and toughness to other carpet components.

[0082] Exemplary embodiments can include those described in the following paragraphs.

[0083] Embodiment A: A carpet comprising: (a) a primary backing layer having a face side and a back side; (b) a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; and (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer comprising at least about 60 wt% propylene-derived units and about 5 to about 25 wt% ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

[0084] Embodiment B: The carpet of Embodiment A, wherein the carpet comprises no more than 150 g/m.sup.2 of latex.

[0085] Embodiment C: The carpet of Embodiments A or B, wherein the carpet comprises no more than 100 g/m.sup.2 of latex.

[0086] Embodiment D: The carpet of any of Embodiments A to C, wherein the carpet comprises no more than 50 g/m.sup.2 of latex.

[0087] Embodiment E: The carpet of any of Embodiments A to D, wherein the carpet comprises no more than 20 g/m.sup.2 of latex.

[0088] Embodiment F: The carpet of any of Embodiments A to E, wherein the carpet comprises 0 g/m.sup.2 of latex.

[0089] Embodiment G: The carpet of any of Embodiments A to F, wherein the fibers comprise at least one of polypropylene, nylon, wool, cotton, acrylic, polyester, and polyethylene terephthalate.

[0090] Embodiment H: The carpet of any of Embodiments A to G, wherein the primary backing layer comprises at least one thermoplastic polyolefin.

[0091] Embodiment I: The carpet of any of Embodiments A to H, wherein the second layer further comprises a filler.

[0092] Embodiment J: The carpet of Embodiment I, wherein the filler is a flame retardant.

[0093] Embodiment K: The carpet of Embodiments I or J, wherein the filler is aluminum trihydrate.

[0094] Embodiment L: The carpet of any of Embodiments A to K, further comprising a third layer attached to the second layer opposite to the primary backing layer.

[0095] Embodiment M: The carpet of Embodiment L, wherein the third layer comprises at least one thermoplastic polyolefin.

[0096] Embodiment N: The carpet of Embodiment M, wherein the third layer further comprises a filler.

[0097] Embodiment O: The carpet of any of Embodiments L to N, wherein a reinforcement layer is present between the second layer and the third layer.

[0098] Embodiment P: The carpet of Embodiment O, wherein the reinforcement layer comprises at least one of thermoplastic fabrics and fiberglass.

[0099] Embodiment Q: The carpet of Embodiments O to P, wherein a middle layer is present between the second layer and the reinforcement layer.

[0100] Embodiment R: The carpet of Embodiment Q, wherein the middle layer comprises at least one thermoplastic polyolefin.

[0101] Embodiment S: A method for making a carpet comprising the steps of: (a) providing a primary backing layer having a face side and a back side, with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; (b) applying a second layer to the back side of the primary backing layer, wherein the layer comprises at least one propylene-based elastomer comprising at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; and (c) forming a carpet; wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

[0102] Embodiment T: The method of Embodiment S, wherein in (b) the second layer is applied to the back side of the primary backing layer by extrusion coating or sheet lamination.

[0103] Embodiment U: A carpet comprising: (a) a primary backing layer having a face side and a back side, wherein the primary backing layer comprises at least one thermoplastic polyolefin; (b) a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer and aluminum trihydrate, wherein the propylene-based elastomer comprises at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, and wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; (d) a third layer attached to the second layer opposite to the primary backing layer, wherein the third layer comprises at least one thermoplastic polyolefin; and (e) a reinforcement layer between the second layer and the third layer, wherein the reinforcement layer comprises at least one of thermoplastic fabrics and fiberglass; wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer, and wherein the carpet comprises 0 g/m.sup.2 of latex.

EXAMPLES

[0104] The foregoing discussion can be further described with reference to the following non-limiting Examples. The examples show the effects of a propylene-based elastomer on yarn adhesion property of a carpet by Samples 1 and 2 in a Velcro roller test. Sample 1 is a carpet sample with a second layer made from 100 wt % of Vistamaxx.TM. 2330 propylene-based elastomer and Sample 2 is one with a second layer made from Vistamaxx.TM. 2330 propylene-based elastomer filled with 60 wt % of aluminum trihydrate (ATH). Areas covered with only yarn were set aside for comparison. Percentages here are based on the total weight of the second layer. The test was conducted by rolling a Velcro type tool back and forth against the surface of Samples 1 and 2 for 20 times. The resulting appearances on the back and front sides of the two samples were examined.

[0105] It is shown in FIG. 2 that the surface appearance was maintained well in the areas with coverage of the propylene-based elastomer while fray or fuzz was formed in the areas with no coverage of the propylene-based elastomer, reflecting good yarn adhesion resulted from the second layer comprising the propylene-based elastomer. It can also be seen by comparing Samples 1 and 2 that the presence of fillers does not produce noticeable difference to the yarn adhesion.

[0106] All documents described herein are incorporated by reference herein, including any priority documents and/or testing procedures. When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. As is apparent from the foregoing general description and the specific embodiments, while forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited thereby.

Claims

1. A carpet comprising: (a) a primary backing layer having a face side and a back side; (b) a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; and (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer comprising at least about 60 wt% propylene-derived units and about 5 to about 25 wt% ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

2. The carpet of claim 1, wherein the carpet comprises no more than 150 g/m.sup.2 of latex.

3. The carpet of claim 1, wherein the carpet comprises no more than 100 g/m.sup.2 of latex.

4. The carpet of claim 1, wherein the carpet comprises no more than 50 g/m.sup.2 of latex.

5. The carpet of claim 1, wherein the carpet comprises no more than 20 g/m.sup.2 of latex.

6. The carpet of claim 1, wherein the carpet comprises 0 g/m.sup.2 of latex.

7. The carpet of claim 1, wherein the fibers comprise at least one of polypropylene, nylon, wool, cotton, acrylic, polyester, and polyethylene terephthalate.

8. The carpet of claim 1, wherein the primary backing layer comprises at least one thermoplastic polyolefin.

9. The carpet of claim 1, wherein the second layer further comprises a filler.

10. The carpet of claim 9, wherein the filler is a flame retardant.

11. The carpet of claim 9, wherein the filler is aluminum trihydrate or calcium carbonate.

12. The carpet of claim 1, further comprising a third layer attached to the second layer opposite to the primary backing layer.

13. The carpet of claim 12, wherein the third layer comprises at least one thermoplastic polyolefin.

14. The carpet of claim 13, wherein the third layer further comprises a filler.

15. The carpet of claim 12, wherein a reinforcement layer is present between the second layer and the third layer.

16. The carpet of claim 15, wherein the reinforcement layer comprises at least one of thermoplastic fabrics and fiberglass.

17. The carpet of claim 15, wherein a middle layer is present between the second layer and the reinforcement layer.

18. The carpet of claim 17, wherein the middle layer comprises at least one thermoplastic polyolefin.

19. A method for making a carpet comprising the steps of: (a) providing a primary backing layer having a face side and a back side, with a plurality of fibers attached to the primary backing layer and extending from both the face side and the back side of the primary backing layer; (b) applying a second layer to the back side of the primary backing layer, wherein the layer comprises at least one propylene-based elastomer comprising at least about 60 wt% propylene-derived units and about 5 to about 25 wt% ethylene-derived units, by weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; and (c) forming a carpet, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer.

20. The method of claim 19, wherein in (b) the second layer is applied to the back side of the primary backing layer by extrusion coating or sheet lamination.

21. A carpet comprising: (a) a primary backing layer having a face side and a back side, wherein the primary backing layer comprises at least one thermoplastic polyolefin; (b) a plurality of fibers tufted into the primary backing layer and extending from both the face side and the back side of the primary backing layer; (c) a second layer attached to the back side of the primary backing layer, comprising at least one propylene-based elastomer, wherein the propylene-based elastomer comprises at least about 60 wt % propylene-derived units and about 5 to about 25 wt % ethylene-derived units, by weight of the propylene-based elastomer, and wherein the propylene-based elastomer has a heat of fusion of less than about 75 J/g; (d) a third layer attached to the second layer opposite to the primary backing layer, wherein the third layer comprises at least one thermoplastic polyolefin; and (e) a reinforcement layer between the second layer and the third layer, wherein the reinforcement layer comprises at least one of thermoplastic fabrics and fiberglass, wherein the second layer substantially locks in the plurality of fibers extending from the back side of the primary backing layer, and wherein the carpet comprises 0 g/m.sup.2 of latex.