U.S. patent application number 09/983033 was filed with the patent office on 2002-09-19 for carpet and carpet making methods.
Invention is credited to Auguste, Jean-Claude, Fink, Wilbert E..
Application Number | 20020132084 09/983033 |
Document ID | / |
Family ID | 27574463 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020132084 |
Kind Code |
A1 |
Fink, Wilbert E. ; et
al. |
September 19, 2002 |
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.
Inventors: |
Fink, Wilbert E.;
(Villanova, PA) ; Auguste, Jean-Claude; (Dayton,
TN) |
Correspondence
Address: |
Samuel C. Miller, III
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
27574463 |
Appl. No.: |
09/983033 |
Filed: |
October 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09983033 |
Oct 22, 2001 |
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09289581 |
Apr 12, 1999 |
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09289581 |
Apr 12, 1999 |
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09240597 |
Feb 1, 1999 |
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09240597 |
Feb 1, 1999 |
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08871500 |
Jun 9, 1997 |
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5876827 |
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08871500 |
Jun 9, 1997 |
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08239317 |
May 6, 1994 |
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08871500 |
Jun 9, 1997 |
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08696462 |
Aug 14, 1996 |
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5728444 |
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08696462 |
Aug 14, 1996 |
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08179321 |
Jan 10, 1994 |
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5578357 |
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08179321 |
Jan 10, 1994 |
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08064380 |
May 21, 1993 |
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5288349 |
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08064380 |
May 21, 1993 |
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07833093 |
Feb 10, 1992 |
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5240530 |
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Current U.S.
Class: |
428/85 ;
156/72 |
Current CPC
Class: |
D06N 2203/042 20130101;
B29C 66/723 20130101; Y02W 30/62 20150501; B32B 2309/12 20130101;
B29C 48/914 20190201; B29B 17/00 20130101; B29C 66/72327 20130101;
D06N 2201/0263 20130101; B29B 2017/0234 20130101; B32B 2309/02
20130101; D06N 2201/12 20130101; D06N 7/0065 20130101; B29C 66/71
20130101; B32B 37/153 20130101; B29C 65/425 20130101; B32B 38/004
20130101; D06N 2201/0254 20130101; B29C 65/42 20130101; B29C
66/1122 20130101; B29L 2009/00 20130101; B32B 5/02 20130101; B29C
48/05 20190201; B29C 66/0242 20130101; B29C 66/83415 20130101; D05C
17/02 20130101; D06N 7/0076 20130101; B29C 66/8221 20130101; D06N
2201/02 20130101; Y02W 30/52 20150501; B29K 2105/26 20130101; B29C
48/9145 20190201; B29C 66/729 20130101; B29C 48/9175 20190201; B29C
48/08 20190201; B32B 2309/06 20130101; Y02W 30/625 20150501; B29C
66/45 20130101; B29C 66/83413 20130101; Y02W 30/524 20150501; B29C
48/022 20190201; Y02W 30/622 20150501; B29B 17/04 20130101; B29C
66/8242 20130101; B29L 2031/7322 20130101; B29C 66/71 20130101;
B29K 2077/00 20130101; B29C 66/71 20130101; B29K 2067/00 20130101;
B29C 66/71 20130101; B29K 2033/12 20130101; B29C 66/71 20130101;
B29K 2033/08 20130101; B29C 66/71 20130101; B29K 2023/12 20130101;
B29C 66/71 20130101; B29K 2023/06 20130101; B29C 66/71 20130101;
B29K 2023/00 20130101 |
Class at
Publication: |
428/85 ;
156/72 |
International
Class: |
A46D 001/00 |
Claims
We claim:
1. A method for manufacturing a carpet comprising (a) fixing tufts
of carpet fibers to a primary backing so that the tufts protrude
from the top surface of the primary backing to form a tufted base
(b) applying a heated sheet of thermoplastic polyolefin, (c)
continuously contacting a lower surface of said tufted base with
said heated sheet, and (d) integrally fusing at least one of the
primary backing or tufts to said heated sheet of thermoplastic
polyolefin.
Description
RELATED APPLICATIONS AND PATENTS
[0001] This application is a continuation-in-part of application
Ser. No. 09/240,597, filed Feb. 1, 1999, which is a continuation of
application Ser. No. 08/871,500, filed Jun. 9, 1997, now U.S. Pat.
No, 5,876,827, which is a continuation-in-part of application Ser.
No. 08/239,317 filed May 6, 1994, and also is a
continuation-in-part of application Ser. No. 08/696,462 filed Aug.
14, 1996, now U.S. Pat. No. 5,728,444, which is a continuation of
application Ser. No. 08/179,321 filed Jan. 10, 1994, now U.S. Pat.
No. 5,578,357, which is a division of Ser. No. 08/064,380, filed
May 21, 1993, now U.S. Pat. No. 5,288,349, which is a division of
Ser. No. 07/833,093 filed Feb. 10, 1992, now U.S. Pat. No.
5,240,530, the contents of all of which are 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.
BACKGROUND
[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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.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).
[0022] 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.
[0023] 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.
[0024] 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).
[0025] In the original parent application Ser. No. 07/883,093, now
U.S. Pat. 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.
[0026] 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.RTM. 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.RTM. test.
[0027] 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
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[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.
[0034] 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.
[0035] 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.
[0036] It is another object of this invention to reduce the cost of
manufacturing carpets.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] Accordingly, it is an object of the present invention to
provide machinery for producing a carpet from a carpet precursor
contacting a polymer sheet.
[0041] These and other objects and features will be apparent from
the detailed descriptive material which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The figures listed below represent preferred embodiments of
the invention described herein.
[0043] FIG. 1 is a cross-sectional view of a carpet being
manufactured in accordance with a preferred embodiment of the
present invention;
[0044] FIG. 2a is a cross-sectional view of a cut pile carpet
precursor;
[0045] FIG. 2b is a cross-sectional view of a cut pile carpet made
in accordance with the teachings of the present invention;
[0046] FIG. 3a is a cross-sectional view of a carpet precursor for
a loop pile carpet;
[0047] FIG. 3b is a cross-sectional view of a loop pile carpet made
in accordance with the teachings of the present invention;
[0048] FIG. 3c is a cross-sectional view of a loop pile carpet with
secondary backing made in accordance with the teachings of the
present invention;
[0049] FIG. 4a is a side schematic view of an apparatus used in the
making of carpet, employing a heated roller;
[0050] FIG. 4b is a pictorial view of an apparatus of the type
described generally in connection with FIG. 2a;
[0051] FIGS. 5a and 5b are graphs illustrating the estimated
temperatures of carpet components as a function of time for the
apparatus of FIGS. 2;
[0052] FIG. 6 is a side schematic view of an apparatus used in the
making of carpet, employing a heated plate;
[0053] FIG. 7 is a side schematic view of an apparatus used in
making carpet employing a continuous, temperature-controlled
surface; and
[0054] FIG. 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
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.degree.
F. higher than the melting point of the greige goods coating, even
more preferably at least about 125.degree. F. higher, and even more
preferably at least about 150.degree. 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.degree. F., more preferably at least about 475.degree. F., even
more preferably at least about 500.degree. F. Of course,
temperatures too high may result in unwanted degradation of the
polymers.
[0059] FIG. 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 FIG. 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.
[0060] 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.
[0061] 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
[0062] FIG. 1 illustrates a preferred embodiment of the present
invention: a carpet product including a face yarn and a backing
material coated with a polymer.
[0063] 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 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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. Pat. No. 5,240,530, herein
incorporated by reference.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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. Pat. 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.
[0080] 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.
[0081] 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
[0082] With reference to FIG. 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.degree. F. above the melting point
of the face yarn, preferably at least 100.degree. 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.
[0083] FIGS. 2 and 3 illustrate, by way of example, two types of
carpet products made in accordance with the teachings of the
present invention. FIG. 2 relates to a cut pile, or grass, carpet
and FIG. 3 relates to a loop pile carpet with optional secondary
backing.
[0084] FIG. 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.
[0085] FIG. 2b depicts a carpet product 210 made from the carpet
precursor of FIG. 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.
[0086] 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.RTM. test without complete wetting by the greige goods
coating of the fiber bundles.
[0087] 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.
[0088] 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).
[0089] FIG. 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.
[0090] FIG. 3b depicts a carpet product 310 made from the carpet
precursor of FIG. 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
FIG. 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.
[0091] 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.RTM. test, as explained previously herein.
[0092] FIG. 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.
[0093] An apparatus for producing a carpet product is illustrated
in FIGS. 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.
[0094] 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 FIG. 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.
[0095] 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 FIG. 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 FIG. 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 FIG. 4, the
roller 432 is 5.9 inches in diameter. The surface of the roller may
be maintained between 330.degree. F. and 650.degree. F. or even
higher, and preferably between 400.degree. F. and 500.degree. F. At
a line speed of about 10 feet per minute, the preferred roller
surface temperature was about 400 to 450.degree. F. using certain
common carpet precursors as described in greater detail in the
examples below.
[0096] The roller 432 may be provided with a surface or coating
which resists sticking. In the system illustrated in FIG. 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.
[0097] 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 FIG. 4b, which shows some additional aspects of the
apparatus of FIG. 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 FIG. 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.
[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.
[0099] As shown in FIG. 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.degree. 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.degree. F. or more above its melting
temperature, to assure good heat bonding.
[0100] The greige goods coating and carpet precursor together pass
between nip roll 454 and casting or chill roll 456. As shown in
FIG. 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.degree. F.
[0101] 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.
[0102] 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.
[0103] 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.
[0104] 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.degree. F. to 600.degree. F. and pressures from 1000-3000 psi.
Typical die melt temperatures range from 450-580.degree. F.
[0105] The apparatus used in the examples described below included
a heated roller of the type shown in FIG. 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.
[0106] 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.
[0107] FIG. 5a presents a calculated temperature profile for the
apparatus of FIG. 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
FIG. 4(a). Trace 504 represents the carpet face temperature at the
points A though E of FIG. 4(a). The dotted line 504 represents the
melting temperature of the back loop yarn. FIG. 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.
[0108] The temperature of the carpet product at various depths (w)
as a function of time (processing stage) was simulated. FIG. 5b is
an example of such a simulation, and contains plots of temperature
at three depths, w1, 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:
1 Material = polypropylene; mp 325.degree. F. Line Speed = 20 ft
per minute Ambient temperature = 90.degree. F. Temp. of melt at
480.degree. F. extrusion die = Temp. of casting roller =
100.degree. F. Temp. of heated 420.degree. F. roller surface = Cast
roller diameter = 5.9 ft. Cast roller wrap angle = 200.degree.
Heated roller diameter = 5.9 ft. Heated roller wrap 220.degree.
angle =
[0109] The times indicated as A, B and C correspond to the
similarly labeled locations in the apparatus of FIG. 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=t.sub.2 (the time when the extruded sheet
first comes into contact with the carpet base). The time t.sub.3 is
the time when the carpet product leaves the cast roller.
[0110] The following table presents a summary of simulations,
including the simulation described in connection with FIG. 5(b),
which is labeled Example 5 in the table.
2 Heated Teflon Wide Prefusion Temp. Coated Angle (.degree. F.)
Between Temp. After (t2) Temp. at (t3) Coating Roll on Time Time
Time t>, t, t > t.sub.2 (Maximum) (.degree. F.) (.degree. F.)
Thickness Temp Prefuse t.sub.1 t.sub.2 t.sub.3 Point Point Point
Ex. (mils) (.degree. F.) Roll (sec.) (sec.) (sec.) w1 w2 w3 w1 w2
w3 w1 w2 w3 1 10 120 90 1.158 2.658 5.233 120 <120 <120 390
300 220 250 240 205 2 10 420 90 1.158 2.658 5.233 400 350 260 450
400 305 270 260 <260 3 -- 420 90 1.158 2.658 5.233 400 350 260
No Extruded 155 149 129 Sheet 4 5 420 90 1.158 2.658 5.233 400 350
260 430 370 275 195 205 205 5 5 420 220 2.832 4.332 6.906 405 380
320 430 380 320 195 215 230
[0111] 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.degree.
(Example 4) and 220.degree. (Example 5). Examples 1-4 have a cast
roller wrap angle of 90.degree.. As indicated above, Example 5 has
a cast roller wrap angle of 200.degree..
[0112] 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.
[0113] 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.degree. 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.
[0114] 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 w1, w2, and w3).
[0115] 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.
[0116] While adjustment of line speed and process temperature
settings may be used, the temperatures w1, w2 and w3 reach
equilibrium much more slowly and involve more complicated
interactions.
[0117] FIG. 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.degree. F. Alternatively, a radiant heater
(not shown) may be substituted for the heated plate 602.
[0118] With continuing reference to FIG. 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.degree. F.
have been employed. Pressures of between 50 to 70 psi at the nip
607 have been employed.
[0119] 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.RTM. 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.
[0120] FIG. 7 is a schematic side view of another embodiment of the
present invention. In FIG. 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.
[0121] The apparatus of FIG. 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.
[0122] 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.
[0123] 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 FIG. 7.
[0124] 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.
[0125] 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 line.
[0126] FIG. 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.
[0127] 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 8b8. 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.
[0128] 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.degree. F. to 550.degree. 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.
[0129] 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.
[0130] The end product of various of the processing steps depicted
in FIG. 8 may have some or all of the following advantageous
features:
[0131] (1) Integrally fused filaments (such as nylon filaments) in
the back loops of the yarn, whereby the finished carpet resists
fuzzing.
[0132] (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.
[0133] (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.
[0134] (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.
[0135] (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.
[0136] (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.
[0137] (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.
[0138] (8) An extruded and cast greige goods coating 816 to which
further layers or backings may be readily adhered or integrally
fused.
[0139] 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
[0140] The process parameters for preparing the carpet products of
the following inventive Example 1 and Comparative Example appear in
the following table.
3 Example 1 Comparative Example 2 Extrusion Temp. (.degree. F.) 600
575 Back Pressure (psi) 430 710 Greige Goods Coating 10 10
Thickness (mils) Nip Pressure (psi) 90 80 Drum Temp. (.degree. F.)
475 Not Applicable (hot oil) Face Fiber nylon nylon Greige Goods
modified ethylene methacrylate Coating Material poly-propylene
(EMA) Velcro Test Result very good; little to no fair to poor;
moderate fuzz to heavy fuzz
Example 1
[0141] 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.degree. 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.degree. 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
[0142] 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.degree. 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
[0143] 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.degree. 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
[0144] 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.degree. 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.
[0145] As shown by the above Examples, the most preferred
embodiments of the invention described herein are as follows:
[0146] (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.
[0147] (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.
[0148] (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.
[0149] 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.
* * * * *