WO2000061853A1

WO2000061853A1 - Carpet and carpet making methods

Info

Publication number: WO2000061853A1
Application number: PCT/US2000/009537
Authority: WO
Inventors: Wilbert E. Fink; Jean-Claude Auguste
Original assignee: Tennessee Valley Patent Development Company
Priority date: 1999-04-12
Filing date: 2000-04-11
Publication date: 2000-10-19
Also published as: US20020039636A1; AU4224900A

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, and extruder and a casting roll against which the extruded sheet and heated carpet are pressed.

Description

WO 00/61853 PCT/TJSOO/09537

CARPET AND CARPET MAKING METHODS

FIELD OF THE DISCLOSURE

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.

BACKGROUND

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.

The basic manufacturing approach to the commercial

production of tufted carpeting is to start with a woven scrim

or primary carpet backing and to feed this into a tufting machine or a loom. The carpet face fiber is needled through

and embedded in the primary carpet backing, thus forming a

carpet precursor or base, sometimes called greige goods.

Upstanding loops on the upper side of the carpet may be cut

to produce cut pile carpet. Yarn loops or knots are usually

exposed on the underside of the greige goods.

Greige goods are typically backed with an adhesive

coating in order to secure the face yarn to the primary

backing. Low cost carpet often receives only a latex

adhesive coating as the backing. This type of carpet is

widely used in boats and is called marine backed carpet .

Typically, the marine backed carpets are backed with a latex

adhesive coating that is water and/or mildew resistant.

Higher cost carpet often receives both a latex adhesive

coating and a secondary backing.

The face fiber or yarn used in forming the pile of a

tufted carpet is typically made of any one of a number of

types of fiber, e.g., nylon, acrylic, polypropylene,

polyethylene, polyester, rayon, wool, cotton and the like.

Face yarns used in carpet include spun staple yarn and bulk

continuous filament (BCF) yarn which is made up of tens or

hundreds of individual fibers, generally about 50-200

individual fibers, though more or less fibers can be used. Fibrillated polypropylene grass yarn is also often used as a

face yarn.

The individual yarn, once made, is often twisted by

itself or in combination with two or more yarns to increase

the total denier. For example, two yarns of 1500 denier each

can be twisted together to produce a 3000 denier yarn, or

three yarns of 1000 denier each can be twisted together to

produce a 3000 denier yarn made up of BCF or spun staple

feeder yarn. The two or more yarns can be the same color or

different colors. Thus, a much wider range of yarn deniers

and colorations is made possible. The yarns often are

textured or air entangled to achieve a different appearance.

The twisting, texturing and air entangling may require that

the yarn receive a spin finish that makes the yarn surface

easier to work with in the fiber processing. However, the

spin finish complicates adhesion of other materials in later

processing, for example, in coating the yarns.

Primary backings for tufted pile carpets are typically

woven or non-woven fabrics made of one or more natural or

synthetic fibers or yarns, such as jute, wool, polypropylene,

polyethylene, polyester, nylon, rayon and the like. Films of

synthetic materials, such as polypropylene, polyethylene and

ethylene-propylene copolymers, may also be used to form the tape for weaving the primary backing. When tape yarns are

used, they are woven into a backing fabric which may consist

of the same or different materials in the warp and fill

directions. The carpet face fiber is usually embedded in the

primary backing such that it wraps around the fill material.

The application of the latex adhesive to the primary

backing involves coating the bottom surface of the formed

greige goods with a latex polymer binder such as a styrene-

butadiene copolymer. The viscosity of the latex adhesive is

similar to water and the latex adhesive flows relatively

easily into the back of the carpet, wetting out the fiber

bundles and penetrating the primary backing. The coated

greige goods are passed through an oven to dry the latex

adhesive coating. In this manner, the face fibers are

attached to the primary backing by the latex binder.

It is known in the art to prepare the greige goods for

coating by subjecting the back of the greige goods to a gas

flame to reduce the bulk of the protruding face yarn,

particularly in greige goods with large knots, in order to

reduce the amount of latex adhesive necessary to provide a

smooth, well -covered surface. It is also known to apply

pressure and low level heat (i.e. below yarn melting temperature) to flatten the knots prior to the application of

the latex adhesive.

If desired, a secondary backing may be bonded to the

undersurface of the primary backing. To produce tufted

carpets with a secondary backing, the bottom surface of the

greige goods is coated with a latex polymer binder. The

secondary backing is applied to the coated bottom surface and

the resulting structure is passed through an oven to dry the

latex adhesive coating to bond the secondary backing to the

greige goods.

Secondary backings for tufted pile carpets are typically

woven or non-woven fabrics made of one or more natural or

synthetic fibers or yarns. In particular, secondary backings

for tufted pile carpets are open weave or leno weave, having

tape yarn in the warp direction, usually of polypropylene,

and spun staple fiber in the fill direction. The spun staple

fiber is very costly, but is used to increase adhesion

between the backing and latex adhesive coating normally used.

The spun stable fiber is hairy when formed and, after the

yarn is woven, it is actually run against an abrasive roll to

make the spun yarn more hairy. The latex is then able to wet

out all the little hairs, improving adhesion of the secondary

backing to the carpet. However, spun staple yarn is not as strong as tape yarn. Therefore, a strong and less expensive

secondary backing material is desirable.

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. See Herligy, The Carpet & Rug Industry,

October 1990. 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 .

Consequently, carpet manufacturers have been attempting

to develop a new approach for the preparation of tufted

carpets. One such method is the preparation of tufted

carpets with a hot-melt adhesive composition instead of a

latex composition. Hot-melt adhesives are amorphous polymers that soften

and flow sufficiently to wet and penetrate the backing

surfaces and tuft stitches of carpets upon application of

sufficient heat. Furthermore, hot-melt adhesives tend to

adhere to the backing surfaces and/or tuft stitches.

The hot-melt compositions are selected for their

adhesive properties in adhering to the tufts of face yarn, to

the primary backing and to the secondary backing, as well as

adhering the various layers of the carpet product to each

other. Such compositions are generally amorphous or

substantially non-crystalline due to the adhesive properties

of such polymers .

By the use of hot-melt adhesive, the necessity of drying

the composition after application is eliminated and, further,

when a secondary backing material is desired, it can be

applied directly after, or in conjunction with, the hot-melt

composition application without requiring an intervening

drying step.

Application of a hot -melt composition is generally

accomplished by passing the bottom surface of the greige

goods over an applicator roll positioned in a reservoir

containing the hot-melt composition in a molten state. A

doctor blade is ordinarily employed to control the amount of adhesive which is transferred from the application roll to

the bottom surface of the structure. Alternatively, the hot

melt adhesive is extruded from a die and falls onto the

greige goods, thereby coating the greige goods. After

application of the hot-melt composition to the bottom surface

of the greige goods, and prior to cooling, the secondary

backing, if desired, is brought into contact with the bottom

surface, and the resulting structure is then passed through

nip rolls and heated.

The activation temperature of a hot-melt adhesive, i.e.,

the temperature at which the adhesive softens and flows

sufficiently to wet and penetrate the backing surfaces and

tuft stitches, is below the temperature at which the backing

and face yarns melt or otherwise distort. Otherwise, the

backing and face yarns may suffer other damage due to

heating.

The compositions which work best as adhesives are those

that can adhere to nylon or other materials from which the

fibers are made. For example, as discussed in GB 971,958,

the adhesive composition may include modified olefins such as

olefin copolymers of ethylene, butylene or propylene with

polar monomers such as, but not limited to, methyl

methacrylate, vinyl acetate, ethyl acrylate and methyl acrylate. The resulting carpet looks good and has many

potential benefits over the latex-coated carpet.

However, it has been found that the tensile strength of

hot-melt adhesives is very low, on the order of one-tenth the

tensile strength of polypropylene, and about one-seventh the

strength of ethylene copolymers. 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^® 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. The

hot-melt adhesive loses some heat to the surrounding air in

the short distance from die or reservoir to carpet . The

carpet further acts as a heat sink for the heat of the hot-

melt adhesive, causing the viscosity to drop off sharply. 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. The tufting process may also stitch several

yarns over each other, in effect burying yarns under

overlapping stitches, thus preventing the adhesive from

reaching all of the fibers. 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. Many of the hot-

melt adhesive compositions conventionally employed in the

manufacture of carpet do not result in reproducible

consistency regarding scrim bonds (force required to remove

the secondary backing from the finished carpet) , tuft pull

strength and fuzz resistance, (an indication of the amount the

individual carpet yarns may fuzz and form pills) .

In the original parent application Serial No.

07/883,093, now U.S. Patent No. 5,240,530, there are

disclosed certain methods for producing carpet. According to

the teachings of that application, a thermoplastic polymer

sheet may be extruded into contact with greige goods to

integrally fuse the primary backing, face yarn and extruded

sheet. Cut pile carpet is presented as exemplifying the use

of the methods. No latex or adhesive application is

required, nor is a backing step required, though one may be

employed in some products .

It is known that latex adhesives, if properly applied,

can provide sufficient binding of carpet fibers to permit

manufacture of loop pile carpets which can pass the Velcro^®

test. It is important that any proposal to replace the use of conventional adhesives be likewise capable of producing a

carpet in which the face yarn or fibers are securely attached

to the carpet, and, in particular, capable of producing loop

pile carpet made with bulk continuous filament (BCF) face

yarn or spun staple yarn which can pass the Velcro^® test.

The present application includes disclosure of improved

carpets and improved techniques for manufacturing carpets

which retain various advantages of the carpets and methods

initially disclosed in the original parent application.

SUMMARY OF THE DISCLOSURE AND

OBJECTS OF THE INVENTION

The present disclosure relates to a novel carpet product

and method and apparatus for producing such a carpet . The

present disclosure further relates to an improved carpet and

method for producing a carpet that overcomes many of the

problems associated with a conventional carpet and carpet

manufacturing processes.

The present disclosure particularly relates to a carpet

having at least a primary backing, a yarn made up of a

plurality of thermoplastic fibers wherein the yarn is tufted

in the primary backing with back loops of fiber on the

underside of the primary backing wherein a portion of substantially all of the plurality of fibers is integrally

fused together, and a greige goods coating of a thermoplastic

polyolefin polymer having recurring polar moieties which

contacts one or more of the integrally fused fibers and

primary backing.

The present disclosure further relates to a process for

manufacturing a carpet including tufting a primary backing

with a yarn to form a carpet base having portions of the yarn

protruding from the upper side of the primary backing and

back loop portions of the yarn exposed on the underside of

the primary backing, heating the underside of the carpet base

to heat the back loop portions of the yarn to integrally fuse

individual fibers of the yarn together, and applying a greige

goods coating of thermoplastic polyolefin polymer having

recurring polar moieties directly to the underside of the

carpet base to adhere or integrally fuse a portion of

substantially all the fibers in the back loops.

A further object of the invention is a carpet having a

primary backing coated on one side with a primary backing

coating of thermoplastic polyolefin polymer having recurring

polar moieties wherein a face yarn made of a plurality of

fibers in a fiber bundle is tufted through the coated primary

backing, having back loops on the underside of the coated primary backing, which adhere or integrally fuse thereto, and

a greige goods coating comprising a second thermoplastic

polyolefin polymer having recurring polar moieties contacting

one or more of the fiber back loops and coated primary

backing .

Another object of the invention is a method for

manufacturing a carpet including coating a primary backing

with a primary backing coating of thermoplastic polyolefin

polymer having recurring polar moieties, fixing tufts of

carpet fibers to the coated primary backing so that the tufts

protrude from the top surface of the coated primary backing

to form a tufted base and back loop portions of the carpet

fibers are exposed on the underside of the primary backing,

contacting the lower surface of the tufted base with a greige

goods coating of thermoplastic polyolefin polymer having

recurring polar moieties, and adhering or integrally fusing

at least one of the coated primary backing or fiber back

loops to the greige goods coating.

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.

The present disclosure further provides a secondary

backing which comprises polypropylene tape yarn in both the

warp and fill directions, thus reducing cost and improving

strength.

It is another object of the present invention to provide

a process for manufacturing a carpet made from thermoplastic

polymers which satisfies commercial requirements relating to

resistance to fuzzing, yarn integrity, tuft binding and

lamination strength.

It is another object of this invention to reduce the

cost of manufacturing carpets.

It is a further object of this invention to improve the

adhesion between layers binding the carpet, thereby improving carpet strength, yarn integrity, tuft binding, laminative

strength and resistance to fuzzing.

The present disclosure also relates to carpet making

machinery. In one embodiment, a carpet precursor is supplied

to an arrangement of rollers including a fluid heated roller

which is pressed against the underside of the carpet

precursor. In a preferred embodiment, an extruder directly

extrudes a hot thermoplastic sheet onto the heated underside

of the carpet precursor. The laminate so formed is pressed

against a cooled casting roll.

In an alternate embodiment of the present invention, a

preformed sheet of thermoplastic polymer is simultaneously

heated and laminated with a carpet precursor in an apparatus

including a continuous moving surface or belt. The belt is

differentially heated so that it is relatively hot at the

location where it first contacts the polymer sheet. The belt

is moved and cooled so that it readily separates from the

underside of the carpet after the carpet precursor and

polymer sheet have been adhered or integrally fused.

Accordingly, it is an object of the present invention to

provide machinery for producing a carpet from a carpet

precursor contacting a polymer sheet. These and other objects and features will be apparent

from the detailed descriptive material which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures listed below represent preferred embodiments

of the invention described herein.

Figure 1 is a cross-sectional view of a carpet being

manufactured in accordance with a preferred embodiment of the

present invention;

Figures 2a is a cross-sectional view of a cut pile

carpet precursor;

Figure 2b is a cross-sectional view of a cut pile carpet

made in accordance with the teachings of the present

invention;

Figure 3a is a cross-sectional view of a carpet

precursor for a loop pile carpet;

Figure 3b is a cross-sectional view of a loop pile

carpet made in accordance with the teachings of the present

invention;

Figure 3c is a cross-sectional view of a loop pile

carpet with secondary backing made in accordance with the

teachings of the present invention; Figure 4a is a side schematic view of an apparatus used

in the making of carpet, employing a heated roller;

Figure 4b is a pictorial view of an apparatus of the

type described generally in connection with Figure 2a;

Figures 5a and 5b are graphs illustrating the estimated

temperatures of carpet components as a function of time for .

the apparatus of Figures 2 ;

Figure 6 is a side schematic view of an apparatus used

in the making of carpet, employing a heated plate;

Figure 7 is a side schematic view of an apparatus used

in making carpet employing a continuous, temperature-

controlled surface; and

Figure 8 is a cross-sectional view of a loop pile carpet

with a coated primary backing made in accordance with the

teachings of one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, a thermoplastic

polymer sheet is laminated with a carpet precursor to form a

carpet product with desirable physical properties.

Generally, the carpet precursor is made of a face yarn which

interpenetrates a primary backing or grid defining the plane of the finished carpet. The carpet precursor may be woven or

knitted.

In preferred embodiments, the carpet precursor has face

yarn tufted in a primary backing and integrally fused to

itself. A greige goods coating of thermoplastic polyolefin

polymer having recurring polar moieties is contacted with the

underside of the formed carpet precursor. A carpet product

with excellent physical properties may be made using the

techniques and apparatus described as follows.

The carpet of the present disclosure is desirably

prepared by feeding a primary carpet backing into a

conventional tufting machine. During the tufting process,

carpet face yarn is also fed into the tufting machine wherein

hundreds of individual tufting needles may be employed to

stitch through the primary carpet backing, thus forming a

continuous web of face fiber tufted through the primary

backing. At this point, the carpet face fiber is secured to

the backing to a degree sufficient for movement of the tufted

material for further processing, but not sufficient for its

use as a finished carpet. The tufted fibers removed from the

tufting machine are called greige goods. The greige goods taken from the tufting machine are

finished to make the material suitable for finished carpet.

First, the greige goods are preferably heated to melt the

tufted fibers together within the primary backing, thereby

integrally fusing the tufted fibers to themselves and/or to

the.primary backing. After fusing the tufted fibers, a

greige goods coating comprising a thermoplastic polyolefin

polymer having recurring polar moieties is applied to the

underside of the greige goods at a temperature sufficiently

high so as to create a heat bond between the primary backing

layer and/or carpet face fiber and the greige goods coating.

A temperature sufficiently high to create a heat bond is a

temperature at least equal to the melting temperature of the

greige goods coating. More preferably, a temperature

sufficiently high enough to create a bond is a temperature at

least about 100°F higher than the melting point of the greige

goods coating, even more preferably at least about 125°F

higher, and even more preferably at least about 150°F higher

than the melting point of the greige goods coating. For

example, if the greige goods coating is polypropylene, a

preferred temperature is at least about 450°F, more

preferably at least about 475°F, even more preferably at

least about 500°F. Of course, temperatures too high may result in unwanted degradation of the polymers.

Figure 1 illustrates some of the features of a carpet

product of a preferred embodiment of the present invention.

A primary backing layer is designated by the numeral 10.

Face yarn is tufted in the primary backing forming a yarn

pile 12 on the upper side of the carpet and back loops or

knots 14 on the bottom. The tufted primary backing 16 is

referred to here as the carpet precursor, carpet base or

greige goods. On the left-hand side of Figure 1, the carpet

face yarn is loosely secured to the backing 10 by the tufting

process to a degree sufficient for movement of the precursor

for further processing, but the precursor is not sufficiently

mechanically stable for use as a finished carpet.

The carpet precursor is desirably heated to a

temperature sufficient to cause melting of the back loops

such that at least a portion of substantially all of the

fibers therein integrally fuse together and/or at least a

portion of the back loops integrally fuse with other back

loops .

The precursor is then laminated with a greige goods

coating 18 in a thickness of from about 3 to 15 mils to form

the carpet product 20. Advantageously, the greige goods

coating is a thermoplastic polyolefin polymer having recurring polar moieties. The carpet precursor is adhered to

or integrally fused with the greige goods coating.

CARPET PRODUCTS

Figure 1 illustrates a preferred embodiment of the

present invention: a carpet product including a face yarn and

a backing material coated with a polymer.

More specifically, preferred embodiments of the carpet

may comprise a primary backing, a face yarn protruding from a

top surface of the primary backing, where the fibers of the

10 face yarn are integrally fused, and a greige goods coating of

a thermoplastic polyolefin polymer having recurring polar

moieties adhered or integrally fused to the back loops of the

face yarn and/or to the bottom surface of the primary

backing.

1.5 The primary backing may preferably be a polypropylene

woven or non-woven material wherein the fill yarn is a

thermoplastic polyolefin polymer having recurring polar

moieties to better facilitate adherence to or integral fusing

with the inside of the fiber bundle back loop.

20 Alternatively, the primary backing may be coated with a

thermoplastic polyolefin polymer having recurring polar moieties before tufting. Again, this facilitates better

adherence to or integral bonding between the primary backing

and the inside of the fiber bundle back loop. Further,

because this primary backing coating may adhere or integrally

fuse with the greige goods coating, it further helps to lock

the fiber bundle in place on the primary backing, preventing

pull-out and fuzzing of the fibers.

The carpet product of the present invention may also

include one or more secondary backing layers adhered or

integrally fused to the carpet precursor by a greige goods

coating. Preferably, the secondary backing comprises tape

yarn in both the warp and fill direction.

The tufts of fiber protruding from the top surface of

the primary backing layer may be of any of the conventionally

used fibers or yarns for tufting carpet. Such materials

preferably include nylon, polyester and polypropylene, or

other thermoplastic synthetic materials when the fibers are

to be integrally fused to themselves. However, the yarns can

include any of the natural or synthetic fibers known by those

skilled in the art. The fibers protruding from the primary

backing may be made of the same material as the primary

backing itself.

Any one or more of the face yarn, primary backing, primary backing coating, secondary backing and greige goods

coating may comprise the same thermoplastic polymer.

Preferably, the thermoplastic polymer is a thermoplastic

polyolefin polymer having recurring polar moieties, also

termed a "polar modified polyolefin" . As used herein, the

phrase "thermoplastic polyolefin polymer having recurring

polar moieties", or "polar modified polyolefin," is meant to

include a random, impact or block copolymer, or a graft

polymer. The polyolefin copolymer comprises, for example,

ethylene, propylene or butylene and polar monomers including,

but not limited to, methacrylate, vinyl acetate, acrylic

acid, methacrylic acid, ethyl acrylate, butyl acrylate and

vinyl alcohol. The graft polymers comprise, for example,

polyethylene, polypropylene or polybutylene having a polar

moiety grafted thereon, wherein the polar moiety is

preferably maleic anhydride (MAH) . Modified polypropylene as

used herein is meant to include both the copolymers of

propylene and graft polymers of polypropylene set forth

above. A polymer of polyolefin and an acrylate as used

herein is meant to include a copolymer of ethylene, propylene

or butylene with one or more of methacrylate, ethyl acrylate

or butyl acrylate, or a graft polymer of polyethylene,

polypropylene or polybutylene with one or more of methacrylate, ethyl acrylate or butyl acrylate. Polymers of

this type are set forth in Table A of U.S. Patent No.

5,240,530, herein incorporated by reference.

In a preferred embodiment, all of the layers of the

carpet comprise the same thermoplastic polyolefin polymer

having recurring polar moieties. In this embodiment, all

layers of the carpet integrally fuse with all other layers,

forming a strong carpet product .

In another embodiment, the primary and secondary backing

and greige goods coating are formed of one polymer and the

face yarn is formed of a different polymer. For example, the

primary and secondary backing and greige goods coating are

formed of a thermoplastic polyolefin polymer having recurring

polar moieties and the face yarn is formed of nylon or

polyester, or of natural materials such as cotton or wool.

In other embodiments, some or all of the backing may be

formed from thermoplastic polyolefin polymer having recurring

polar moieties. It is preferred, however, to use a polymer

for the primary and secondary backings with melting points

similar to that of the greige goods coating to facilitate

adhesion to, or, preferably, integral fusion with the greige

goods coating. In some carpets, the bottom layer (either the greige

goods coating or secondary backing) may be formed from a

blend of thermoplastic polyolefin polymer having recurring

polar moieties and thermoplastic elastomer to provide some

properties of the elastomer such as flexibility, non-skid

character and other properties similar to rubber.

The primary backing of the carpet product may include

any synthetic resin that will integrally fuse with the greige

goods coating and may be, for example, a woven or non-woven

fabric, a film or a web. Preferably, the primary backing is

made of a thermoplastic polyolefin polymer, copolymer or

terpolymer in the warp direction, with a thermoplastic

polyolefin polymer having recurring polar moieties in the

fill direction, preferably a maleic anhydride graft polymer

of polypropylene. This facilitates adhesion or integral

fusion of the interior of the fiber bundle with the primary

backing, helping to prevent pull-out of the fibers and making

total penetration of the adhesive coating into the fiber

bundle unnecessary.

Further, the primary backing may be coated with a

thermoplastic polymer, such as a thermoplastic polyolefin

polymer having recurring polar moieties as discussed herein

throughout, before tufting of the fibers through the primary backing. The primary backing coating is preferably in an

amount of from about 0.5 to 5.0 mils thick. Coating the

primary backing before tufting promotes adhesion or integral

fusion of the interior of the fiber bundles with the primary

backing upon heating. Again, this helps to secure the fibers

in place without necessitating total penetration of the fiber

bundle by the adhesive coating. Further, where the primary

backing coating is exposed to the greige goods coating

through the fiber back loops, adhesion or integral fusion of

the primary backing coating and greige goods coating will

occur, effectively trapping the fiber bundle between the

primary backing coating and greige goods coating. This

increases tuft bind strength of the resultant carpet.

The secondary backing material, if applied, may

preferably include any synthetic resin that will adhere or

integrally fuse with the greige goods coating.

Advantageously, the secondary backing will comprise the same

thermoplastic polyolefin polymer having recurring polar

moieties as the primary backing. The secondary backing for

the carpets of the present disclosure may comprise a woven or

non-woven fabric. A woven secondary backing may be an open

weave or leno weave, preferably having tape yarn in both the

warp direction and in the fill direction. However, the open weave is not necessary to obtain a suitable bond as may be

required with use of a latex adhesive.

The greige goods coating may be formed from a

thermoplastic polyolefin polymer having recurring polar

moieties. A preferred greige goods coating is a copolymer of

ethylene or a graft polymer of polypropylene. Preferably,

the greige goods coating is applied in an amount of from

about 3 to 15 mils.

The thermoplastic polyolefin polymer having recurring

polar moieties used in the greige goods coating may be

compounded with inert fillers by either extrusion compounding

or mixing operations. Such fillers may include calcium

carbonate, silicates, talc, calcium, glass fibers, carbon

black and wood flour. Other fillers may also be suitable.

The use of such fillers in the greige goods coating may

range from about 0.1% to as high as about 50%. At the high

levels, an exceedingly stiff board like material may be made

that may be used, e.g., as a trunk liner, molded floor mat or

a ■ door panel in an automobile. Because addition of a filler

significantly alters the performance and process ability of

the polymer, filled systems may be designed to satisfy a

particular product need with minimum effect on other

performance aspects. It is desirable that, for some use applications, carpet

made in accordance with the present invention pass the "pill

test" (ASTM D-2859) for fire resistance. Thus, in some

applications where enhanced flame resistance is required, a

fire-retardant may be added to the feedstock used to produce

the greige goods coating.

Optionally, blends of the thermoplastic polyolefin

polymers having recurring polar moieties and thermoplastic

elastomers may be used to make the greige goods coating or

co-extruded layer. The thermoplastic elastomers (TPE's) are

a diverse family of rubber-like materials that, unlike

vulcanized rubbers, may be processed and recycled as

thermoplastics. A listing of some suitable TPE's is given in

parent patent U.S. Patent No. 5,240,530 at Table A, column

11, which is hereby incorporated by reference. The TPE's are

not merely substitutes for thermosetting polymers, but may

also replace or improve their properties. There are four

general groups of TPE ' s that may be suitable for use in the

present invention. The four general groups include

polyurethanes, copolyesters, styrene block copolymers, and

polyolefins. Blending the elastomer with the polyolefin

polymer provides some of the properties of the elastomer at a

lower cost. The compatibility is good for blends ranging from about 10 to 97% elastomer based on the total amount of

thermoplastic polyolefin polymer having recurring polar

moieties and elastomer.

As a class, the TPE's may provide toughness, flexibility

over a wide temperature range, and resistance to abrasion,

weathering, and a variety of solvents and other chemicals.

Thus, the properties of each of the materials in the group

may be tailored for use in the carpet of the present

invention by polymerization methods, blending, and

incorporation of additives, fillers, and reinforcements to

form carpets having enhanced abrasion, weathering and

chemical resistance.

Depending on the material composition of each of the

possible carpet layers (yarn, primary backing, primary

backing coating, greige goods coating, secondary backing) ,

various adjacent or overlapping carpet layers will adhere or integrally fuse. Integral fusion is typically achieved using

chemically similar thermoplastics which melt together, while

adhesion requires that the materials stick together by either

chemical or mechanical means. Adhered materials typically

may be separated into the component parts. Adhesion and

integral fusion of the various carpet components as disclosed may provide a carpet having improved strength, fuzz

resistance and longevity.

IMPROVED METHODS AND APPARATUS FOR CARPET MANUFACTURE

With reference to Figure 1, an improved method of making

a carpet product according to the invention is generally

illustrated. Heat and pressure are applied (for example, by

a heated roller) to the underside of the carpet precursor at

location 22 sufficient to heat the underside of the carpet

precursor to above the melting point of the face yarn. This

preheating of the carpet precursor causes a portion of

substantially all of the fibers in the back loops of the face

yarn to integrally fuse together. Generally, the temperature

should be about 50°F above the melting point of the face

yarn, preferably at least 100°F above the melting point of

the face yarn. A heated greige goods coating of

thermoplastic polyolefin polymer having recurring polar

moieties 18 is brought into contact with the heated carpet

precursor at location 24 whereby the laminated carpet product

20 is produced. The carpet product may either be the

finished carpet or subjected to further processing, e.g.

application of additional backings. Figures 2 and 3 illustrate, by way of example, two types

of carpet products made in accordance with the teachings of

the present invention. Figure 2 relates to a cut pile, or

grass, carpet and Figure 3 relates to a loop pile carpet with

optional secondary backing.

Figure 2a depicts a carpet precursor 200 from which a

carpet, for example, grass carpet, is made. A woven primary

backing 202 is interpenetrated by fibrillated isotactic

polypropylene yarn 204 in a preferred embodiment. Cut yarn

ends or tufts 206 form the pile of the carpet. The yarn is

loosely secured in place by back loops 208 exposed on the

underside of the carpet precursor. In this example the

backing 202 is a woven fabric made of polypropylene.

Figure 2b depicts a carpet product 210 made from the

carpet precursor of Figure 2a. A greige goods coating 212 of

thermoplastic polyolefin polymer having recurring polar

moieties has been integrally fused to the carpet precursor

200. As shown in the figure, the back loops 208 and portions

of the primary backing 202 have been heat bonded (i.e.,

adhered or integrally fused) with the greige goods coating

212. Spaces between the primary backing 202 and the greige

goods coating 212 may be larger or smaller depending on the

penetration of the greige goods coating into the primary backing during manufacture. In fact, the greige goods

coating may more or less conform to the shape of the bottom

surface of the primary backing and encapsulate the back

loops. Thus, there may be little, if any, space between the

greige goods coating and the primary backing. The underside

214 of the carpet product may be essentially flat due to the

cooling contact made with the surface of a casting roller

during processing.

During manufacture, the back loops 208 may be heated

sufficiently for individual fibrils of the yarn to integrally

fuse with each other. The preliminary heating of the carpet

precursor raises the temperature of the carpet precursor

above the melting point of the yarn, melting at least a

portion of substantially all of the individual fibers of the

yarn in the back loops such that the yarn fibers melt and

flow together, integrally fusing the individual fibers to

each other both within a tuft and between tufts of yarn. The

heat of the greige goods coating contacting the primary

backing and integrally fused fibrils of yarn also may

partially melt the polymers therein sufficient to form a heat

bond with the greige goods coating. This enhances the

mechanical durability of the resulting carpet product.

Further, the integral fusing of the fibers lessens the need for the greige goods coating to fully wet and penetrate the

back loops of yarn. The integral fusing of the fibers around

the primary backing sufficiently secures the fibers in place

such that the carpet material will pass the Velcro^® test

without complete wetting by the greige goods coating of the

fiber bundles.

Preferably, the primary backing comprises a

thermoplastic polyolefin polymer having recurring polar

moieties in the fill direction, such that heating the carpet

precursor allows the fill yarn to bond with the inside of the

fiber bundle loop. A fill yarn made from thermoplastic

polyolefin polymer having recurring polar moieties,

preferably a graft polyolefin polymer such as maleic

anhydride modified polypropylene, adheres to the innermost

part of the fiber bundle back loop when heated. This

provides a more secure bond between the fiber bundle back

loop and the fill yarn around which it is wrapped, helping to

prevent pull-out of the fibers from the primary backing. By

bonding the internal part of the fiber bundle back loop to

the fill yarn of the primary backing, total penetration and

wetting of the back loops by the greige goods coating is no

longer required to hold the fibers in place. Alternatively, the primary backing may be coated with a

primary backing coating of thermoplastic polyolefin polymer

having recurring polar moieties before tufting the yarn

through the backing. The primary backing coating is

preferably a polypropylene graft polymer with maleic

anhydride. The primary backing coating is preferably in an

amount of from about 0.5 to 5.0 mils thick. Upon heating,

the coated primary backing will adhere or integrally fuse to

the inside of the fiber bundle back loop, preventing pull-out

of the fibers and reducing the need to totally penetrate the

fiber bundles with the greige goods coating to ensure

sufficient tuft bond strength. Further, the primary backing

coating may adhere or integrally fuse with the greige goods

coating, thereby locking the fiber back loop between the two

coatings, holding it securely in place (see Fig. 8) .

Figure 3a depicts a carpet precursor 300 from which a

level loop pile carpet is made. A woven primary backing 302

is interpenetrated by a multi-fiber face yarn or bulk

continuous filament (BCF) yarn 304. Such yarn may be a

twisted array of, for example, 120 small denier fibers. Yarn

loops or tufts 306 form the pile of the carpet. The yarn is

mechanically secured to the backing 302 by back loops 308

exposed on the underside of the carpet precursor. In this example the BCF yarn is made of polypropylene and the backing

302 is a woven fabric also made of polypropylene.

Figure 3b depicts a carpet product 310 made from the

carpet precursor of Figure 3a. A greige goods coating 312 of

thermoplastic polyolefin polymer having recurring polar

moieties has been integrally fused to the carpet precursor

300. As shown in the figure, the back loops 308 and portions

of the backing have been heat bonded with the greige goods

coating 312. As in the example of Figure 2a, some voids or

spaces may occur between the greige goods coating and carpet

precursor. Alternatively, the upper portion of the greige

goods coating may partially or totally encapsulate the back

loops .

During manufacture, the back loops 308 are preferably

partially melted so that individual fibers making up the yarn

are integrally fused with each other by preheating of the

carpet precursor before contacting it with the hot greige

goods coating. The heat of the greige goods coating may

further partially melt the integrally fused fibers such that

they heat bond with the greige goods coating and/or the

primary backing 302. It has been observed experimentally

that this improves the mechanical stability of the resulting

carpet product and secures the tufts and component yarn fibers to a sufficient degree that the carpet product can

pass the Velcro^® test, as explained previously herein.

Figure 3c depicts a carpet product 320 which includes an

optional secondary backing 322. In this example, the

secondary backing is laminated with the hot greige goods

coating 312 and integrally fuses with it. Preferably, the

secondary backing is a tape yarn in both the weave and fill

directions. More preferably, the tape yarn is a

thermoplastic polyolefin polymer having recurring polar

moieties for optimal adherence to or integral fusing with the

greige goods coating.

An apparatus for producing a carpet product is

illustrated in Figures 4a and 4b. Carpet precursor or greige

goods 430 is supplied at location 431 with the carpet pile

facing downwardly. The carpet precursor is placed in contact

with a heated roller 432, whereby the underside of the carpet

precursor is heated. This results in heating of the back

loops or knots of the carpet precursor which may be partially

melted therefrom, causing the fibers of the back loops to

integrally fuse. The heated carpet precursor 434 travels

downstream in the apparatus for lamination with a greige

goods coating 436. The greige goods coating may be a thermoplastic

polyolefin polymer having recurring polar moieties, such as a

copolymer or a graft polymer. The coating may be applied as

a hot extrusion such as from a die as shown in Figure 4, or

as a preformed film or sheet which is heated to allow heat

bonding to the carpet precursor, which preferentially is

itself preheated. The greige goods coating may be heated

before application to the carpet precursor, or after contact

therewith.

The heated roller 432 may advantageously be a fluid or

oil heated roller, although other means may be employed to

uniformly heat the surface of the roller, such as electrical

resistance elements. When heated fluid is employed, the

fluid enters the system at 438 (while shown in Figure 4a off-

center, the fluid inlet is typically at the center of the

roll) , is circulated in the roller 432 and exits at 440

(while shown in Figure 4a off-center, the fluid outlet is

typically at the center of the roll) . The oil is reheated

and recirculated in a closed loop system designated generally

by numeral 441. Advantageously, the system is operated to

maintain the surface of the roller 432 at a uniform

temperature across the width of the roller. The optimum

surface temperature of the roller is dependent on a number of variables, including the structure and composition of the

carpet precursor, line speed, roller pressure and the area of

the contact between the roller 432 and the carpet precursor.

In the system illustrated in Figure 4, the roller 432 is 5.9

inches in diameter. The surface of the roller may be

maintained between 330°F and 650°F or even higher, and

preferably between 400°F and 500°F. At a line speed of about

10 feet per minute, the preferred roller surface temperature

was about 400 to 450 °F using certain common carpet precursors

as described in greater detail in the examples below.

The roller 432 may be provided with a surface or coating

which resists sticking. In the system illustrated in Figure

4, the roller 432 is wrapped with teflon tape. A doctor

blade 442 may be provided to remove built-up polymer melted

from the underside of the carpet precursor.

Water cooled nip roll 444 may be provided which,

together with the tension in the running carpet precursor,

holds the underside of the carpet precursor against the

heated roller. With reference to Figure 4b, which shows some

additional aspects of the apparatus of Figure 4a in

perspective view, the heated roller and auxiliary rollers are

designated 432' and 444', respectively. The auxiliary

rollers 444 ' are rotatably mounted to a pivoting bar assembly 446. The pressure of the carpet precursor against the heated

roller is controlled by applying pressure to the pivoting bar

assembly 446 by means of hydraulic actuators 448. The

pressure at nips 450 and 450' have been desirably controlled

to provide a contact pressure at a tangential point between

the nip rolls 450 and 450' and chill roll 432 of between 1

and 4 pounds per linear inch of width with a gap setting

between the respective rolls prior to introducing the carpet

precursor of between zero and one inch. The contact pressure

and gap setting will depend upon the thickness and density of

the carpet precursor. In the apparatus of Figure 4, the

hydraulic pressure may typically be set at 460 to 480 pounds

per square inch to obtain the desired contact pressure at the

recited gap setting.

Referring once more to Figure 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 .

As shown in Figure 4a, the heated carpet precursor 434

travels a short distance "d" to be laminated with the greige

goods coating 436. Preferably, this distance is as short as

possible to minimize heat loss from the carpet precursor.

The heated carpet precursor 434 preferably may contact the

heated greige goods coating as it is directly extruded

downwardly onto the underside of the carpet precursor. The

greige goods coating is formed by forcing a thermoplastic

polyolefin polymer having recurring polar moieties feedstock

451 through an extrusion die 452. In examples discussed

below, the extrusion die temperature is about 510°F.

Alternatively, the greige goods coating may be a preformed

sheet or film made by any method known in the art, including

extrusion and casting. It is desirable that the greige goods

coating be above its melting temperature when it contacts the

carpet precursor, advantageously 100°F or more above its

melting temperature, to assure good heat bonding. The greige goods coating and carpet precursor together

pass between nip roll 454 and casting or chill roll 456. As

shown in Figure 4b, the nip roller 454' may be rotatably

mounted on parallel pivoting arms 458. The nip roller and

pivoting arms exert a pressure against the upper side of the

carpet precursor which consequently presses the greige goods

coating against the casting roller 456 ' . A contact pressure

at a tangential point between the nip roller 454 and the

chill roller 456 of between 1 and 4 pounds per linear inch of

width with a gap setting between the respective rolls prior

to introducing the carpet precursor of between zero and one

inch has been desirably utilized. The contact pressure and

gap setting will depend upon the thickness and density of the

carpet precursor. Advantageously, the casting roller is

maintained at a controlled temperature. In the examples

discussed below, that temperature is 130°F.

A carpet product 460 is produced which may be subjected

to additional processing. Optionally a secondary woven

backing or non-woven backing (not shown) may be

simultaneously laminated to the greige goods coating 436 at

the casting roll 456.

In order to control shrinking of the carpet precursor or

carpet product, a tenter frame (not shown) may be employed during the preheating and lamination operations or

thereafter.

Various polymers have been extruded or laminated onto

carpet precursors as greige goods coatings. In particular,

trials have been conducted using polypropylene homopolymer

(prime virgin 5 mils) , polypropylene copolymer (recycled from

shrink film) , polypropylene homopolymer (recycled from

fiber) , and thermoplastic elastomer polypropylene blend

(50/50 blend) . Alternatively, other thermoplastic polyolefin

polymers having recurring polar moieties, including

copolymers of ethylene, propylene and butylene with polar

monomers such as methacrylate, vinyl acetate, acrylic acid,

methacrylic acid, ethyl acrylate, butyl acrylate and vinyl

alcohol, or graft polymers of polyethylene, polypropylene and

polybutylene with polar moieties such as maleic anhydride,

may be used as greige goods coatings. In all the trials, the

extruded sheet exhibited good bonding strength to the back of

the carpet. The greige goods used in the trials included a

polypropylene primary backing with polypropylene face fiber

and a polypropylene primary backing with nylon face fiber.

In addition, certain carpet trials included a secondary

backing of woven polypropylene. The secondary backing was found to exhibit good adhesion with all the polymer types

listed.

The extrusion trials were conducted with a 1.5 inch

diameter, 24:1 (barrel length to diameter ratio) Sterling

extruder. The extruder had a 20 horsepower DC drive and a

single stage screw. The extruder was equipped with three

heating zones, a screen pack collar and a pressure gauge.

Speed was controlled by a variable resistor dial and a

tachometer was connected to an RPM dial for speed indication.

Typical extruder temperatures range from 340°F to 600°F and

pressures from 1000-3000 psi . Typical die melt temperatures

range from 450-580°F.

The apparatus used in the examples described below

included a heated roller of the type shown in Figure 4. In

that apparatus, the die width was 12 inches. The molten

polymer from the die was deposited on a water cooled casting

roll (7.9 inch diameter, 13 inch width) . Water was passed

through helical passages within the casting roll at high

velocity to cool the casting roll as required. The nip roll

was 3 inches in diameter. The casting roll assembly was

driven by an eddy current clutch and a 1.5 horsepower motor.

While speeds of 10 feet per minute were actually used in

the examples described below, it is contemplated that higher speeds would be used in commercial production. In

particular, since there is no drying step, speeds of 100 to

300 feet per minute appear possible. Carpet widths of 12 to

15 feet may be produced. Such speeds and widths require

appropriate material and handling capability to move large

rolls in and out of the process quickly. Thus, in contrast

to conventional processes, the factor limiting line speed may

be material handling and not the conventional adhesive drying

step, which is eliminated in the practice of the present

method.

Figure 5a presents a calculated temperature profile for

the apparatus of Figure 4 in graphical form. Temperature is

represented on the vertical axis; time/position is

represented on the horizontal axis. Trace 500 represents the

back loop temperature at various points in the process

designated by letters A though E which correspond to

similarly labeled locations in the apparatus of Figure 4 (a) .

Trace 504 represents the carpet face temperature at the

points A though E of Figure 4 (a) . The dotted line 504

represents the melting temperature of the back loop yarn.

Figure 5a illustrates a temperature profile in which the back

loops are maintained above their melting temperature, while the temperature of the carpet face always remains below the

melting temperature.

The temperature of the carpet product at various depths

(w) as a function of time (processing stage) was simulated.

Figure 5b is an example of such a simulation, and contains

plots of temperature at three depths, wl , w2 and w3 , which

are respectively 2 mils, 6 mils and 14 mils into the backside

of the carpet base. The simulation is based on the following

assumed properties and parameters:

Material = polypropylene; mp 325°F

Line Speed = 20 ft per minute

Ambient temperature = 90°F

Temp, of melt at extrusion die = 480°F

Temp, of casting roller =100°F

Temp, of heated roller surface = 420°F

Cast roller diameter = 5.9 ft .

Cast roller wrap angle = 200°

Heated roller diameter = 5.9 ft.

Heated roller wrap angle = 220°

The times indicated as A, B and C correspond to the similarly

labeled locations in the apparatus of Figure 4a. More specifically, time A corresponds to t=o, time B corresponds

to t=t (the time at which the carpet base leaves the heated

roller) , and time C corresponds to t=t₂ (the time when the

extruded sheet first comes into contact with the carpet

base) . The time t₃ is the time when the carpet product

leaves the cast roller.

The following table presents a summary of simulations,

including the simulation described in connection with Figure

5(b), which is labeled Example 5 in the table.

Examples 1 and 2 compare a simulated process with and

without heat being applied to the heated roller. Example 3

illustrates the effect on the simulation of eliminating the

greige goods coating. Examples 4 and 5 employ a 5 mil extruded coating and compare the process for a heated roll

wrap angle of 90° (Example 4) and 220° (Example 5) . Examples

1-4 have a cast roller wrap angle of 90°. As indicated

above, Example 5 has a cast roller wrap angle of 200°.

The examples illustrate how process parameters may be

used to control the internal temperatures of the carpet

product at various depths to achieve melting of yarn fibers

and integral fusing of yarn fibers with each other and with

the greige goods coating and primary backing, without

thermally degrading the face yarn or primary backing during

processing.

The carpet base of preferred embodiments of the

present invention is a woven polypropylene primary carpet

backing. This backing is woven from polypropylene tapes

(tape thickness 1.0 to 2.0 mils). Preferably, one tape is a

modified tape of thermoplastic polyolefin polymer having

recurring polar moieties, preferably in the fill direction.

The thermoplastic polyolefin polymer having recurring polar

moieties may consist of an ethylene, propylene or butylene

copolymer, or graft polymer of polyethylene, polypropylene or

polybutylene. Preferably, the modified tape is a graft polymer of polypropylene and maleic anhydride. The tapes are

machine direction oriented to arrive at tensile strengths in

the range of about 4 to 6 grams per denier. Orientation of

the thermoplastic polyolefin polymer involves organization of

the crystalline structure by controlled handling and cooling

during production. This process makes it possible to make

the backing strong enough for the end carpet use. However,

the backing cannot be heated for too long to a temperature

above the original orientation temperature (240 to 280°F)

without damaging the orientations of the thermoplastic

polyolefin polymer. If the orientation is lost substantially

throughout the tape thickness, the strength of the backing is

compromised.

It will be clear from the foregoing that variable

wrap angles may be used at a constant line speed to change

the internal carpet temperatures without changing the

apparatus temperature settings or the process speed. The

process response to a wrap angle change is relatively

instantaneous. The process response to apparatus temperature

setting and line speed changes is much slower (i.e., it takes a relatively long time to reach the desired equilibrium

process temperature at points wl, w2 , and w3) .

This feature is very important, particularly for a

commercial carpet manufacturer who must routinely make many

varieties of carpet (e.g. often the same carpet style will be

offered in one color line but at three different face fiber

weights or qualities) . In such cases, adjustment of the wrap

angles can provide the necessary heat adjustment (to

accommodate the three different face weights) on the fly.

Likewise, adjustment of wrap angles may facilitate start-up

of a line and avoid burning through the carpet base when the

line runs initially at a slow speed.

While adjustment of line speed and process

temperature settings may be used, the temperatures wl , w2 and

w3 reach equilibrium much more slowly and involve more

complicated interactions.

Figure 6 is a schematic side view of an alternative

embodiment of the present invention. The underside of a

carpet precursor 600 is passed in contact with an

electrically heated plate 602. The carpet precursor 600 may

be pressed between the electrically heated plate 602 and a second plate 604 whose temperature is not controlled.

Preferentially, electrically heated plate 602 is oriented at

an angle with respect to second plate 604 in order to

gradually increase the pressure exerted on the carpet

precursor and iron the back loops as the carpet precursor

moves from right to left across the electrically heated plate

602. Successful trials of the apparatus have been run where

the surface temperature of the plate 604 was set at 600°F.

Alternatively, a radiant heater (not shown) may be

substituted for the heated plate 602.

With continuing reference to Figure 6, heated carpet

precursor 606 is drawn to the nip 607 formed between nip

roller 608 and casting roller 610. A greige goods coating

612 is extruded directly onto the underside of the heated

carpet precursor from extrusion die 614. Casting roll

temperatures between 80 and 120°F have been employed.

Pressures of between 50 to 70 psi at the nip 607 have been

employed.

Temperature variations across the heated plate 602

have been observed to produce variation across the width of

the carpet product. Cool areas produce regions in loop pile BCF carpet, for example, which fail the Velcro^® test. Hot

areas produce regions of apparent excess shrinkage and face

yarn damage. In addition, the hot areas may deposit

excessive melted polymer from the greige goods coating onto

the heated plate.

Figure 7 is a schematic side view of another

embodiment of the present invention. In Figure 7, a carpet

precursor 700 is supplied to the apparatus, pile side down.

A sheet 702 of greige goods coating is also supplied to the

apparatus. The sheet 702 may either be freshly extruded in a

manner similar to that described above, or it may be formed

at a different time and/or location and supplied from a feed

roll.

The apparatus of Figure 7 includes a first

differentially heated and cooled surface 704. The surface

functions both as a heated surface for integrally fusing the

greige goods coating sheet 702 to the carpet precursor 700

and as a casting surface for forming and cooling the

underside of the carpet product .

In preferred embodiments of the present invention,

the surface 704 is a continuous belt which travels around heated cylinder 706 and cooled cylinder 708. Stationery

heating and cooling units 710 and 712, respectively, may also

be provided to adjust the temperature profile around the path

of travel of the belt 714.

In operation, the belt is differentially heated so

that it is relatively hot at location 714 where it first

contacts the greige goods coating sheet 702. At a

downstream location 716, the heated greige goods coating

sheet contacts the carpet precursor, the combination of which

is moved and cooled as the belt travels from left to right in

Figure 7.

A lower continuous belt system 718 may be provided

for applying pressure to the upper side of the carpet

product. An upper surface 720 of the lower belt may be

oriented at an angle with respect to the upper belt as

illustrated in order to gradually increase the pressure

exerted on the carpet product . The temperature of the lower

belt 718 may also be controlled in a manner similar to belt

704, albeit at lower temperatures.

At location 722, the carpet product and belt are

sufficiently cool that the carpet product readily separates from the belt without leaving significant amounts of melted

polymer (preferably no melted polymer) on the belt 704. From

this location the carpet product travels downstream in the

production 1ine .

Figure 8 is a cross-sectional view illustrating a

carpet and carpet-making process in accordance with a more

preferred embodiment of the present invention. In the

Figure, processing distances have been compressed for

illustration purposes, and processing steps illustrated

schematically. Though this process is shown as a continuous

process, it will be understood that various steps may be

performed on different manufacturing lines at different

times. The illustrated process begins with a primary backing

800 (shown here as a woven primary carpet backing with warp

strands 802 and fill strands 804) . Advantageously the

primary backing is made of thermoplastic polyolefin polymer

having recurring polar moieties.

A thermoplastic primary backing coating 806 may be

applied to the primary backing 800. This layer may be

omitted in some embodiments. Preferably, the primary backing

coating 806 is produced by extruding a thermoplastic polyolefin polymer having recurrent polar moieties onto one

side of the primary backing 800 from extruder 808. Yarn 810

interpenetrates the coated primary backing 812.

Advantageously, the yarn may be a nylon multi-filament yarn.

The yarn is tufted, looped or punched through the coated

primary backing to form back loops such as 814.

At the indicated location, pressure and/or heat may

be applied to the product . This process may be performed by

the heated roller systems described above. Where the yarn is

multi-filament yarn, at least a portion of the back loop will

be heated above the melting point of the yarn material so

that at least a portion of substantially all of the filaments

integrally fuse to one another. If the yarn is nylon, this

may require temperatures in the range of 520°F to 550°F.

Because the yarn is typically twisted, it will be understood

that this step may require heating only a portion (for

example about 50%) of the thickness of the yarn to a

temperature and pressure sufficient to affect integral

fusing.

At a point later in the process, a second

thermoplastic layer, or greige goods coating, 816 is applied to the carpet product. In a preferred embodiment, this layer

is produced by extruding a second thermoplastic polyolefin

polymer having recurrent polar moieties onto the carpet base

812 from extruder 818. The greige goods coating may be

extruded in hot, essentially molten, form directly onto the

carpet product while the carpet base is still hot from the

heating and pressing step.

The end product of various of the processing steps

depicted in Figure 8 may have some or all of the following

advantageous features :

(1) Integrally fused filaments (such as nylon

filaments) in the back loops of the yarn,

whereby the finished carpet resists fuzzing.

(2) A primary backing 800 of thermoplastic

polyolefin polymer (especially one having

recurring polar moieties) integrally fused

or adhered with the primary backing coating

806 such as at interface 820.

(3) A primary backing 800 of

thermoplastic polyolefin polymer

(especially one having recurring polar moieties) integrally fused or

adhered with the integrally fused

filaments in the back loops 814.

(4) A primary backing coating of thermoplastic

polyolefin polymer having recurring polar

moieties adhered or integrally fused to

inner portions of carpet back loops, such as

at interface 822.

(5) Pressure flattened back loops such as at 824

onto which further layers or backings may

readily be applied. The back loops

themselves may be integrally fused to one

another .

(6) A greige goods coating 816 adhered or

integrally fused to the lower portions of

the back loops and/or the primary backing

coating 806 such as at interface 826.

(7) A greige goods coating 816 integrally fused

or adhered to portions of the primary

backing 800 and/or primary backing coating

806 such as at interface 828. (8) An extruded and cast greige goods

coating 816 to which further layers

or backings may be readily adhered or

integrally fused.

One product of the foregoing process is a durable

carpet with nylon face yarn and a flexible, rollable

polyolefin based backing which has physical properties

described in the art as a "good hand."

EXAMPLES

The process parameters for preparing the carpet

products of the following inventive Example 1 and Comparative

Example appear in the following table.

EXAMPLE 1

A sample of carpet of the present disclosure was

prepared according to the methods described herein. In

particular, a nylon face fiber was tufted on a primary

backing, to form a carpet precursor. The back side of the

formed carpet precursor was heated on a hot oil drum at a

temperature of 475°F to pre-fuse the nylon face fibers to

themselves. A greige goods coating of a polypropylene graft

polymer with maleic anhydride manufactured by Morton Chemical

under the name of Tymor 212599-2 was extruded in molten form

from a die at a temperature of 600°F onto the pre-fused

carpet precursor at a thickness of 10 mils. The coated

carpet precursor was then run through a nip roll at a nip pressure of 90 psi and a back pressure of 430 psi before

cooling. A Velcro test performed 24 hours after formation of

the carpet product indicated a very good bond with little to

no fuzzing, indicative of integral fusing of the nylon fibers

to themselves and good adhesion or integral fusing between

each of the greige goods coating, primary backing and fused

fibers.

COMPARATIVE EXAMPLE

This example was prepared using a nylon face fiber

and a greige goods coating of ethylene methacrylate (EMA)

(24% methacrylate content) provided by Exxon. This sample

was not pre-fused or pre-heated. After tufting, the carpet

precursor was contacted with the greige goods coating

extruded at a temperature of 575°F to a thickness of 10 mils.

The nip pressure was 80 psi, and the back pressure was 710

psi. The Velcro test, performed 24 hours after formation of

the carpet product, resulted in moderate to heavy fuzz, with

large numbers of individual fibers being pulled out of the

carpet product . EXAMPLE 2

A carpet is made having a nylon face fiber and a

primary backing of polypropylene in the warp direction and

maleic anhydride graft polypropylene polymer in the fill

direction. Upon preheating to a temperature of about 460-

550°F, portions of substantially all of the nylon fibers

integrally fuse together, and the fill yarn adheres to the

inside portion of the nylon fiber back loop. The pre-fused

carpet precursor is coated with about 10 mils of extruded

maleic anhydride graft polypropylene polymer and cooled. The

greige goods coating integrally fuses to at least the fill

yarn of the primary backing and adheres to the nylon fibers .

The carpet thus made will have little to no fuzz and a high

tuft pull strength.

EXAMPLE 3

A carpet is made having a nylon face fiber and a

primary backing of polypropylene coated on one side with a

primary backing coating of ethylene methacrylate. Upon

preheating to a. temperature of about 460-550°F, portions of

substantially all of the nylon fibers integrally fuse together, and the primary backing coating adheres to the

inside portion of the nylon fiber back loop. The preheated

carpet precursor is coated with about 10 mils of extruded

ethylene methacrylate and cooled. The greige goods coating

integrally fuses to at least the primary backing coating and

adheres to the nylon fibers. The carpet thus made will have

little to no fuzz and a high tuft pull strength.

As shown by the above Examples, the most preferred

embodiments of the invention described herein are as follows:

(1) A carpet having a primary backing,

preferably of polypropylene, a face yarn made up of a

plurality of nylon fibers tufted in the primary backing so

that back loops of yarn are on the underside of the primary

backing, wherein the nylon fibers are integrally fused

together by pre-heating, and a greige goods coating of a

thermoplastic polyolefin polymer having recurring polar

moieties, preferably a maleic anhydride graft polymer of

polypropylene, applied to the carpet precursor after pre¬

heating so that the greige goods coating adheres to one or

more of the integrally fused fibers and primary backing. (2) A carpet having a primary backing wherein

the fill yarn is a thermoplastic polyolefin polymer having

recurring polar moieties, preferably a maleic anhydride graft

polymer of polypropylene, a face yarn made up of a plurality

of nylon fibers tufted in the primary backing so that back

loops of yarn are on the underside of the primary backing,

and a greige goods coating of thermoplastic polyolefin,

wherein the fill yarn adheres to the inside of the nylon

fiber back loop.

(3) A carpet having a primary backing coated

with a thermoplastic polyolefin polymer having recurring

polar moieties, preferably ethylene methacrylate, a face yarn

made up of a plurality of nylon fibers tufted in the primary

backing so that back loops of yarn are on the underside of

the primary backing, and a greige goods coating of

thermoplastic polyolefin, preferably of the same composition

as the primary backing coating, wherein the inside of the

back loops of the face yarn adheres to the primary backing

coating, and the primary backing coating and greige goods

coating integrally fuse, locking the yarn fibers in place. From the foregoing description, one of ordinary skill

in the art can ascertain the essential characteristics of the

present invention, and without departing from the spirit and

scope thereof, can make changes and modifications of the

disclosed techniques to adapt them to various uses and

conditions. As such, these changes and modifications are

properly within the scope of the range of equivalents of the

following claims.

Claims

WE CLAIM:

1. A carpet comprising: a primary backing; a yarn made up of a plurality of thermoplastic fibers, said yarn being tufted in said primary backing and having back loops on the underside of the primary backing, wherein a portion of substantially all of the plurality of fibers of the yarn in said back loops is integrally fused together; and a greige goods coating of a thermoplastic polyolefin polymer having recurring polar moieties which contacts one or more of said integrally fused fibers and said primary backing.

2. The carpet of claim 1, wherein the greige goods coating is a copolymer of propylene, ethylene or butylene with a polar moiety selected from the group consisting of methacrylate, vinyl acetate, acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate and vinyl alcohol.

3. The carpet of claim 1, wherein the greige goods coating is a graft polymer of polypropylene, polyethylene or polybutylene with a polar moiety.

4. The carpet of claim 1, wherein the plurality of fibers is integrally fused at a temperature at least 50°F greater than the melting point of the fibers.

5. The carpet of claim 1, wherein the plurality of fibers is integrally fused at a temperature at least 100°F greater than the melting point of the fibers.

6. The carpet of claim 1, wherein the primary backing comprises polypropylene.

7. The carpet of claim 6, wherein the primary backing comprises propylene copolymer or polypropylene graft polymer in either a warp or a fill direction which adheres to the integrally fused fibers.

8. The carpet of claim 6 , wherein the primary backing comprises propylene copolymer or polypropylene graft polymer in either a warp or a fill direction which integrally fuses to the integrally fused fibers.

9. The carpet of claim 1, wherein the yarn is nylon bulk continuous fiber yarn, the primary backing is a thermoplastic polyolefin polymer, and the greige goods coating is an extruded sheet comprising a copolymer of ethylene, propylene or butylene and a polar acrylate.

10. The carpet of claim 1, wherein the primary backing is coated with a primary backing coating comprising a thermoplastic polyolefin polymer having recurring polar moieties before said yarn is tufted in said primary backing, and wherein said tufted yarn integrally fuses or adheres to the coated primary backing.

11. The carpet of claim 10, wherein the primary backing coating is 0.5-5.0 mils thick.

12. The carpet of claim 10, wherein the primary backing coating comprises a graft polymer of polypropylene and maleic anhydride .

13. The carpet of claim 1, further comprising a second backing adhered or integrally fused to the greige goods coating such that the greige goods coating is between the primary backing and second backing.

14. The carpet of claim 13, wherein the second backing comprises polyolefin tape yarn in both warp and fill directions.

15. The carpet of claim 1, wherein the greige goods coating adheres to one or more of the integrally fused fibers and the primary backing.

16. The carpet of claim 1, wherein the greige goods coating integrally fuses to one or more of the integrally fused fibers and the primary backing.

17. The carpet of claim 1, wherein the greige goods coating is between 3 and 15 mils in thickness, and wherein upper portions of the coating surround said back loops.

18. The carpet of claim 1, wherein the yarn fibers are selected from the group consisting of nylon, polypropylene, polyester, polyethylene, acrylic and a combination thereof.

19. The carpet of claim 1, wherein the carpet has a tuft bind strength of at least 4 pounds .

20. A carpet which comprises: a primary backing having a primary backing coating of a thermoplastic polyolefin polymer having recurring polar moieties; a face yarn made of a plurality of fibers in a fiber bundle, said yarn being tufted in said coated primary backing and having back loops on the underside of the coated primary backing, wherein the fiber bundle contacts the coated primary backing; and a greige goods coating comprising a thermoplastic polyolefin polymer which contacts one or more of said fiber back loops and coated primary backing.

21. The carpet of claim 20, wherein the fiber bundle adheres or integrally fuses to the coated primary backing.

22. The carpet of claim 20, wherein the plurality of fibers of the yarn in said back loops is integrally fused.

23. The carpet of claim 22, wherein the plurality of fibers is integrally fused at a temperature at least 50°F greater than the melting point of the fibers.

24. The carpet of claim 22, wherein the plurality of fibers is integrally fused at a temperature at least 100°F greater than the melting point of the fibers.

25. The carpet of claim 20, wherein the primary backing comprises polypropylene.

26. The carpet of claim 20, wherein the primary backing coating is 0.5-5.0 mils thick.

27. The carpet of claim 20, wherein the primary backing coating comprises a graft polymer of polypropylene and maleic anhydride .

28. The carpet of claim 20, further comprising a second backing such that the greige goods coating is between the primary backing and second backing.

29. The carpet of claim 28, wherein the second backing comprises polyolefin tape yarn in both the warp and fill directions .

30. The carpet of claim 20, wherein the greige goods coating adheres to one or more of the fiber back loops and the coated primary backing.

31. The carpet of claim 20, wherein the greige goods coating integrally fuses to one or more of the fiber back loops and the coated primary backing.

32. The carpet of claim 20, wherein the greige goods coating is a thermoplastic polyolefin polymer having recurring polar moieties.

33. The carpet of claim 20, wherein the greige goods coating is between 3 and 15 mils in thickness, and wherein upper portions of the greige goods coating surround said back loops.

34. The carpet of claim 20, wherein the yarn fibers are selected from the group consisting of nylon, polypropylene, polyester, polyethylene, acrylic and a combination thereof.

35. The carpet of claim 20, wherein the carpet has a tuft bind strength of at least 4 pounds.

36. A carpet comprising: a primary backing; a yarn made up of a plurality of thermoplastic fibers, said yarn being tufted in said primary backing and having back loops on the underside of the primary backing; a greige goods coating of a thermoplastic polyolefin polymer which contacts one or more of said plurality of fibers and said primary backing, wherein said primary backing comprises polypropylene tape in one direction, and a tape of thermoplastic polyolefin polymer having recurring polar moieties in a second direction.

37. The carpet of claim 36, wherein the tape of thermoplastic polyolefin polymer having recurring polar moieties is a polypropylene graft polymer or propylene copolymer .

38. The carpet of claim 36, wherein the tape of thermoplastic polyolefin polymer having recurring polar moieties is a maleic anhydride graft polymer of polypropylene .

39. The carpet of claim 36, wherein the tape of thermoplastic polyolefin polymer having recurring polar moieties is in a fill direction.

40. A method of making a carpet comprising: tufting a primary backing with yarn to form a carpet base with portions of the yarn protruding from the upper side of the primary backing and with back loop portions of the yarn exposed on the underside of the primary backing; heating the underside of the carpet base to heat the back loop portions of the yarn sufficient to integrally fuse the individual fibers of the yarn together; applying a greige goods coating of a thermoplastic polyolefin polymer having recurring polar moieties onto the underside of the carpet base., whereby said greige goods coating adheres to fibers in the back loops.

41. The method of claim 40, wherein the yarn, greige goods coating and primary backing are integrally fused.

42. The method of claim 40, wherein the greige goods coating is 3 to 15 mils thick.

43. The method of claim 40, wherein the primary backing comprises polypropylene.

44. The method of claim 43, wherein the primary backing comprises propylene copolymer or polypropylene graft polymer in one or more of a warp or a fill direction and is adhered to the integrally fused fibers.

45. The method of claim 43, wherein the primary backing comprises propylene copolymer or polypropylene graft polymer in one or more of a warp or a fill direction and is integrally fused to the integrally fused fibers.

46. The method of claim 40, further comprising contacting a second backing to the greige goods coating such that the greige goods coating is between the primary backing and second backing.

47. The method of claim 46, wherein the second backing comprises polyolefin tape yarn in both the warp and fill directions.

48. The method of claim 40, wherein the carpet has a tuft bind strength of at least 4 pounds.

49. The method of claim 40, wherein the yarn fibers are selected from the group consisting of nylon, polypropylene, polyester, polyethylene, acrylic and a combination thereof.

50. A method for manufacturing a carpet comprising; coating a primary backing with a primary backing coating of a thermoplastic polyolefin polymer having recurring polar moieties; fixing tufts of carpet fibers to the coated primary backing so that the tufts protrude from the top surface of the coated primary backing to form a tufted base and back loop portions of the carpet fibers are exposed on the underside of the primary backing; applying a greige goods coating of a thermoplastic polyolefin polymer to at least one of the coated primary backing or back loops .

51. The method of claim 50, further comprising the step of applying a second backing such that the greige goods coating is between the primary backing and second backing.

52. The method of claim 51, wherein the second backing comprises polyolefin tape yarn in both the warp and fill directions .

53. The method of claim 50, wherein the carpet has a tuft bind strength of at least 4 pounds.

54. The method of claim 50, wherein the step of applying the greige goods coating integrally fuses the greige goods coating to one or more of the fiber back loops and the coated primary backing.

55. The method of claim 50, wherein the primary backing coating is 0.5-5.0 mils thick.

56. The method of claim 50, wherein the primary backing coating comprises a graft polymer of polypropylene and maleic anhydride .

57. The method of claim 50, wherein the yarn fibers are selected from the group consisting of nylon, polypropylene, polyester, polyethylene, acrylic and a combination thereof.

58. The carpet of claim 50, wherein the greige goods coating is a thermoplastic polyolefin polymer having recurring polar moieties.

59. The method of claim 50, further comprising integrally fusing the fibers to themselves.

60. The method of claim 59, wherein the fibers are integrally fused at a temperature at least 50°F greater than the melting point of the fibers.

61. The method of claim 60, wherein the fibers are integrally fused at a temperature at least 100°F greater than the melting point of the fibers.

62. A method of making a carpet comprising: forming a primary baking comprising a polypropylene tape in one direction and a tape of thermoplastic polyolefin polymer having recurring polar moieties in the other direction; tufting the primary backing with yarn to form a carpet base with portions of the yarn protruding from the upper side of the primary backing and with back loop portions of the yarn exposed on the underside of the primary backing; and applying a greige goods coating of a thermoplastic polyolefin polymer to the underside of the carpet base, whereby said greige goods coating adheres to the fibers of the back loops .