Carpet and carpet making methods

Abstract

The disclosure relates to a carpet product, a process for manufacturing carpet, and an apparatus used in a carpet manufacturing process. The carpet product is made from tufted polymer filament yarn wherein the individual yarn filaments of the yarn back loops are integrally fused so that the carpet resists fuzzing. The primary backing preferably is modified polypropylene in the fill direction. Further, the primary backing may be coated with a polymer before tufting to adhere or integrally fuse the inside of the fiber tuft to the primary backing. An optional secondary backing is preferably made of tape yarn in both directions. The process includes providing a carpet base having a primary backing penetrated by yarn, applying heat to the underside of the primary backing, extruding a heated sheet of polymer and continuously contacting the heated extruded sheet of polymer with the base. The apparatus includes a source of carpet precursor, a heated cylinder for heating the underside of the carpet, an extruder and a casting roll against which the extruded sheet and heated carpet are pressed.

Description

RELATED APPLICATIONS AND PATENTS[0001] This application is a continuation of application Serial No. 09 / 289,581 filed Apr. 12, 1999, the contents of which is hereby incorporated by reference.FIELD OF THE DISCLOSURE[0002] The application relates to pile carpet and, in particular, to a carpet in which the face yarn is secured to one or more backing layers. Apparatus and methods for manufacturing such carpet are also disclosed.[0003] Most carpets are composite structures in which the face fiber forming the pile, i.e., the surface of the carpet, penetrates at least one backing layer. The base portions of the facing yarn extend through the backing and are exposed on the bottom surface of the primary backing. Such carpets, generally termed tufted carpets, may be cut pile or loop pile. Aspects of the present invention are also applicable to most other types of carpet, including woven or knitted carpets such as Berber carpets and certain sports surfaces, such as artificial turf or grass.[000...

AI Technical Summary

Benefits of technology

[0033] It is a further object of the invention that the primary backing adhere or integrally fuse to the yarn fibers. Preferably, the primary backing comprises at least in either the warp or fill direction a thermoplastic polyolefin polymer having recurring polar moieties, allowing the fibers of the face yarn to better adhere to the primary backing around which they are wrapped, thereby preventing pull-out of the fibers. Advantageously, the thermoplastic polyolefin polymer having recurring polar moieties is in the fill direction. Further, it is preferable that the thermoplastic polyolefin polymer having recurring polar moieties for use in the primary backing is a propylene copolymer or polypropylene graft polymer. Various specific compositions are employed in preferred embodiment of the present invention.

[0098] Referring once more to FIG. 4a, the rollers 444 may be mounted so that their axes of rotation can be selectively positioned along lines 445. An additional roller 447 may be provided, whose axis of rotation may be selectively positioned along line 449. During line start-up, rollers 44 and 47 may be moved downwardly so that the path of the greige goods 430 is located out of contact with the heated roller 432, thereby preventing overheating of the greige goods as it is being threaded into the line. In addition, during operation, the location of rollers 444 along lines 445 may be adjusted to vary the heat input into the greige goods. Thus, the heated roller temperature can be maintained constant and the wrap angle (i.e. residence time) of the greige goods adjusted for line parameter variations such as greige goods weight.

Problems solved by technology

However, the spin finish complicates adhesion of other materials in later processing, for example, in coating the yarns.

The spun staple fiber is very costly, but is used to increase adhesion between the backing and latex adhesive coating normally used.

However, spun staple yarn is not as strong as tape yarn.

The above-described methods have disadvantages in that they require a drying step and thus an oven to dry the latex polymer binder.

The drying step increases the cost of the carpet and limits production speed.

Furthermore, it has been reported that latex adhesive compositions generate gasses that may be the cause of headaches, watery eyes, breathing difficulties and nausea, especially when used in tightly sealed buildings.

An additional problem sometimes encountered with the latex coating is that the latex may go all the way through the primary backing and ruin the appearance of the carpet due to excessive penetration caused by the low viscosity of the latex.

In addition, overheating of the carpet may occur during drying of the latex, which in turn may affect the shade of the carpet.

Furthermore, hot-melt adhesives tend to adhere to the backing surfaces and / or tuft stitches.

Otherwise, the backing and face yarns may suffer other damage due to heating.

Therefore, hot-melt adhesive carpets generally are deficient in tuft pull strength (force required to remove a tuft from the carpet), particularly as measured by the fiberblock test or "Velcro Test," wherein a two pound Velcro.RTM. roller approximately three and one-half inches wide and one and one-half inches in diameter of well-known hook and loop fastening material is rolled repeatedly over the loop pile of the carpet, for example, ten times. The carpet is then inspected for protruding fibers or fuzz (short individual filaments removed from the fiber bundles).

A further problem with hot-melt adhesive is that it begins to loose temperature and increase in viscosity as soon as it leaves the die or is extracted from the reservoir.

Nip pressure can be applied to help the hot-melt adhesive to penetrate the greige goods, but this forces the melt against and into the relatively cold carpet, even further lowering the melt temperature and viscosity.

This is even further complicated by the fact that the carpet can be made from yarns that have been twisted together, for example, two or more feeder yarns twisted into one larger yarn.

Any finish or coating such as a spin finish that may have been originally applied to the yarn also complicates this by making adhesion of the melt difficult.

The result is that total penetration and wetting of the yarn back loops is usually not achieved and, thus, the tuft pull strength is very low.

Thus, conventional carpet and carpet manufacturing processes have inherent problems.

Specifically, the adhesives used to adhere the tufts of face fiber to the primary backing and to adhere the secondary backing to the primary backing include compositions which require lengthy drying times, thus slowing down the manufacturing process.

Further, these adhesives may excessively penetrate the fibers, distorting the appearance of the carpet face.

In addition, use of latex compositions as adhesives may produce noxious gases which create health hazards.

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