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

[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: Ser. No._____________, entitled "ETHYLENE POLYMER CARPET, CARPET BACKINGS AND METHODS"; Ser. No._______________ entitled "CARPET BACKINGS AND METHODS USING SUBSTANTIALLY LINEAR ETHYLENE POLYMERS METHODS"; Ser. No. ______________ entitled "CARPETS, CARPET BACKINGS AND METHODS USING SUBSTANTIALLY LINEAR ETHYLENE POLYMERS METHODS"; and Ser. 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.[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 invention relates to a carpet and a metho...

AI Technical Summary

Benefits of technology

show that two station extrusion of homogenously branched ethylene polymers results in carpet samples with good flexibility and good cohesion of the carpet components. The top layer can also contain fillers or recycled polymeric materials to modify properties or for cost savings.

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 yam, 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.

However, the preferred TREF technique does not include purge quantities in SCBDI or CDBI calculations.

That is, polyolefin polymer mixtures can involve sufficiently similar polymer chemistries, compatibilities, and / or miscibilities to permit good recyclability without having sufficient similarities to permit integral fusion.

In addition, because it is not relied on for encapsulating or penetrating the fiber bundles, a resin of lower quality and / or less tightly controlled properties may be used in the second layer.

Two high pressure LDPE, a heterogeneously branched LLDPE, and a heterogeneously branched ULDPE extrusion coating (Comparative Runs 9-12) resulted in relatively stiff carpet samples and relatively poor carpet component cohesiveness.

One indication of poor component cohesiveness was relatively low adhesiveness of the backing material to the primary backing material.

That is, lower extrusion temperatures will generally require slower extrusion line speeds to achieve good penetration of the yarn.

Practitioners will also appreciate that excessive chemical stabilization may adversely effect draw down performance, thus additive selection and concentration must be balanced against draw down requirements and penetration requirements.

The high pressure LDPE extrusion coating resin resulted in stiff carpet with poor component cohesiveness.

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