Carpet, carpet backings and methods

Abstract

The present invention pertains to carpet and method of making it. In one aspect, 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. The method can include additional steps or procedures, either separately or in various combinations. Additional steps and procedures include preheating the primary backing prior the extrusion step, multilayer adhesive backings, washing or scouring the primary backing prior the extrusion step, and utilizing adhesive polymeric additives, high heat content fillers, blowing agents and / or implosion agents. The constructions and methods described herein are particularly suited for making carpet tile.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001] This application is a continuation-in-part application from U.S. Provisional Application No. 60 / 039,217 filed Feb. 28, 1997, which application was in turn related to pending applications: Serial No. ______, entitled "ETHYLENE POLYMER CARPET, CARPET BACKINGS AND METHODS"; Serial No. ______ entitled "CARPET BACKINGS AND METHODS USING SUBSTANTIALLY LINEAR ETHYLENE POLYMERS METHODS"; Serial No. ______ entitled "CARPETS, CARPET BACKINGS AND METHODS USING SUBSTANTIALLY LINEAR ETHYLENE POLYMERS METHODS"; and Serial No. ______ entitled "CARPETS, CARPET BACKINGS AND METHODS USING HOMOGENEOUS LINEAR ETHYLENE POLYMERS," all four of which were filed on Feb. 28, 1997, and the disclosures of which are incorporated herein by reference.FIELD OF THE INVENTION[0002] This invention relates to carpets and methods of making carpets, wherein, for each, the carpets comprise at least one flexible ethylene polymer backing material. In a particular instance, the ...

AI Technical Summary

Benefits of technology

[0030] A fifth aspect of the present invention is a method of making a carpet, the carpet comprising yarn attached to a primary backing material and an adhesive backing material, the adhesive backing material comprises at least one homogeneously branched ethylene polymer characterized as having a short chain branching distribution index (SCBDI) of greater than or equal to 50 percent, and wherein the adhesive backing material is in intimate contact with the primary backing material and has substantially penetrated and substantially consolidated the yarn, the method comprising the step of adding an effective amount of a high heat content filler to the adhesive backing material to substantially extend the semi-molten or molten time of the adhesive backing material and enhance the penetration of the adhesive backing material into the yarn.

[0037] A twelfth aspect of the invention is a method of making a carpet, and the carpet so made, which method includes the steps of providing a primary backing material having a face and a back side, tufting a yarn into the primary backing material to produce a carpet pile on the faze side of the primary backing material and loops of the yarn on the back side of the primary backing material, extruding a first sheet of a first thermoplastic material to the back side of the primary backing, and extruding a second sheet of a second thermoplastic material adjacent the first sheet. In this twelfth aspect, the melt viscosity of the thermoplastic material in the first sheet is lower than the melt viscosity of the thermoplastic material in the second sheet so as to provide for enhanced penetration of the thermoplastic material in the first sheet into at least one of the primary backing material or the loops of yarn on the back side of the primary backing material.

[0038] A thirteenth aspect of the present invention is a method of making a carpet with an extruded sheet as part of its backing wherein prior to the extruding step, at least the back side of the primary backing and loops of the yarn on the back side of the primary backing are treated to remove undesirable chemicals from the surface and thereby enhance the adhesion of the extruded sheet.

Problems solved by technology

Third, some carpet styles include both loop and cut pile.

As one important drawback, typical latex adhesive backing systems do not provide a moisture barrier.

Another possible drawback, particularly with a carpet having polypropylene yarn and polypropylene primary and secondary backing materials, is the dissimilar polymer of latex systems along with the inorganic filler can reduce the recyclability of the carpet.

However, urethane backing systems also have important drawbacks, including their relatively high cost and demanding curing requirements which necessitate application at slow carpet production rates relative to latex systems.

However, using polyolefins to replace latex adhesive backings can also present difficulties.

For example, U.S. Pat. No. 5,240,530, Table A at Col. 10, indicates that ordinary polyolefin resins possess inadequate adhesion for use in carpet construction.

Additionally, relative to latex and other cured systems, ordinary polyolefins have relatively high application viscosities and relatively high thermal requirements.

High recrystallization temperatures result in relatively short molten times during processing and, combined with high melt viscosities can make it difficult to achieve adequate penetration of the yarn, especially at conventional adhesive backing application rates.

Unfortunately, hot melt adhesive systems are generally considered not completely suitable replacements for conventional latex adhesive backings.

Typical hot melt systems based on EVA and other copolymers of ethylene and unsaturated comonomers can require considerable formulating and yet often yield inadequate tuft bind strengths.

However, the most significant deficiency of typical hot melt system is their melt strengths which are generally too low to permit application by a direct extrusion coating technique.

As such, polyolefin hot melt systems are typically applied to primary backings by relatively slow, less efficient techniques such as by the use of heated doctor blades or rotating melt transfer rollers.

While unformulated high pressure low density polyethylene (LDPE) can be applied by a conventional extrusion coating technique, LDPE resins typically have poor flexibility which can result in excessive carpet stiffness.

Conversely, those ordinary polyolefins that have improved flexibility, such as ultra low density polyethylene (ULDPE) and ethylene / propylene interpolymers, still do not possess sufficient flexibility, have excessively low melt strengths and / or tend to draw resonate during extrusion coating.

To overcome extrusion coating difficulties, ordinary polyolefins with sufficient flexibility can be applied by lamination techniques to insure adequate yarn-to-backing adhesion; however, lamination techniques are typically expensive and can result in extended production rates relative to direct extrusion coating techniques.

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