U.S. patent application number 11/337102 was filed with the patent office on 2006-09-14 for carpets with improved fuzz-resistance.
This patent application is currently assigned to Propex Fabrics, Inc.. Invention is credited to Hugh Chester Gardner, Jeffrey H. Mumm.
Application Number | 20060204711 11/337102 |
Document ID | / |
Family ID | 26858787 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060204711 |
Kind Code |
A1 |
Mumm; Jeffrey H. ; et
al. |
September 14, 2006 |
Carpets with improved fuzz-resistance
Abstract
Tufted carpets bonded with thermoplastic binders and having
improved resistance to fuzz formation due to removal of pile yarn
filaments from tuft bundles comprise one or more backings, face
yarn that forms a pile on one side and stitches on an opposite
side, a thermoplastic binder that binds stitches and the backing or
backings, and an organic polymer that bonds filaments of the
stitches. Processes for making carpets comprise applying to a
stitched side of a tufted backing a liquid stitch bind composition
comprising an organic polymer component, removing a liquid
component of the composition to bond filaments of the stitches and
bonding stitches and one or more backings with a thermoplastic
binder that is melted or applied as a melt in contact with the
stitched side and the backing or backings and solidified.
Inventors: |
Mumm; Jeffrey H.; (Marietta,
GA) ; Gardner; Hugh Chester; (Roswell, GA) |
Correspondence
Address: |
KING & SPALDING LLP
1180 PEACHTREE STREET
ATLANTA
GA
30309
US
|
Assignee: |
Propex Fabrics, Inc.
Austell
GA
|
Family ID: |
26858787 |
Appl. No.: |
11/337102 |
Filed: |
January 20, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
09696519 |
Oct 25, 2000 |
7018492 |
|
|
11337102 |
Jan 20, 2006 |
|
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60162463 |
Oct 29, 1999 |
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Current U.S.
Class: |
428/95 ;
428/97 |
Current CPC
Class: |
D06N 7/0076 20130101;
D06N 2201/02 20130101; Y10T 428/23979 20150401; Y10T 428/23993
20150401; D06N 2201/0254 20130101; D06N 2201/0263 20130101; D06N
2205/06 20130101; D06N 2213/065 20130101; D06N 7/0073 20130101;
Y10T 428/23986 20150401; D06N 2201/0227 20130101 |
Class at
Publication: |
428/095 ;
428/097 |
International
Class: |
D05C 17/00 20060101
D05C017/00 |
Claims
1-27. (canceled)
28. A tufted carpet comprising: a backing; face yarn comprising a
plurality of filaments; an organic polymer component; a
thermoplastic binder, wherein the face yarn penetrates the backing
such that a plurality of tufts of the face yarn project from a
surface of the backing, wherein the thermoplastic binder consists
entirely or essentially of a thermoplastic polyethylene-having flow
properties corresponding to an MI of about 2.2 to about 105 g/10
min. as measured in accordance with ASTM D 1238; and a viscosity
between approximately 230,000 and 4,881,000 cps at about
270.degree. F. with a shear rate of about 10 sec.sup.-1 as measured
in accordance with ASTM D 3835; a plurality of face yarn stitches
are disposed on an opposite surface of the backing; a plurality of
filaments of the face yarn stitches are bonded by the organic
polymer component; and a plurality of stitches are bonded within
the tufted carpet with the thermoplastic binder.
29. The carpet of claim 28, further comprising a secondary backing
that is bonded to a stitched surface of the backing with the
thermoplastic binder.
30. The carpet of claim 28, having a Fuzz Rating of 4 or less.
31. The carpet according to claim 28, having a tuft bind strength
of at least about 2 pounds.
32. The carpet according to claim 28, having a tuft bind strength
of at least about 5 pounds.
33. The carpet according to claim 28, containing less than 3 osy
crosslinked polymer solids.
34. The carpet according to claim 28, wherein the organic polymer
has a weight of 0.2 to 3 ounces per square yard of stitched surface
of the tufted carpet.
35. The carpet of claim 28, wherein the backing comprises a woven
polypropylene fabric tufted with face yarn.
37. The carpet of claim 28, wherein the face yarn comprises nylon
filaments.
38. The carpet of claim 28, wherein the face yarn comprises
polyester filaments.
39. A carpet comprising: a backing comprising a stitched side; face
yarn comprising a plurality of filaments; a stitch bind composition
comprising an organic polymer component, the stitch bind
composition joined with the stitched side of the backing; a
thermoplastic binder, wherein the face yarn penetrates the backing
such that a plurality of tufts of the face yarn project from a
surface of the backing opposite to the stitched side of the
backing, wherein the thermoplastic binder consists entirely or
essentially of a thermoplastic polyethylene-having flow properties
corresponding to an MI of about 2.2 to about 105 g/10 min. as
measured in accordance with ASTM D 1238; and a viscosity between
approximately 230,000 and 4,881,000 cps at about 270.degree. F.
with a shear rate of about 10 sec.sup.-1 as measured in accordance
with ASTM D 3835; a plurality of filaments of face yarn stitches
are bonded by stitch bind composition on the stitched side of the
backing; and a plurality of stitches are bonded within the carpet
with the thermoplastic binder.
40. The carpet of claim 39, wherein the thermoplastic binder
comprises a nonwoven fabric needled to the backing.
41. The carpet of claim 39, wherein the organic polymer component
comprises a film-forming organic polymer.
42. The carpet of claim 39, wherein the organic polymer component
comprises a thermoplastic polymer.
43. The carpet of claim 39, wherein the organic polymer component
comprises a crosslinkable organic polymer.
44. The carpet of claim 39, wherein the stitch bind composition
comprises a crosslinking agent for the organic polymer.
45. The carpet of claim 39, wherein the organic polymer component
comprises an olefin-unsaturated acid, olefin-unsaturated acid ester
or olefin-diene copolymer.
46. The carpet of claim 39, wherein the organic polymer component
comprises an ethylene acrylic acid copolymer.
47. The carpet of claim 39, wherein the organic polymer component
comprises a styrene acrylate copolymer.
48. The carpet of claim 39, wherein the organic polymer component
comprises a carboxylated styrene butadiene copolymer.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/162,463 filed Oct. 29, 1999.
FIELD OF THE INVENTION
[0002] This intention relates to carpets and their manufacture and
more particularly carpets and carpet manufacture involving
thermoplastic binders.
BACKGROUND OF THE INVENTION
[0003] Tufted carpets generally comprise a backing, face yarn and a
binder. The face yarn penetrates the backing such that a plurality
of tufts projects from one side of the backing and a plurality of
face yarn stitches is disposed on an opposite side of the backing.
The binder is present on the stitched side, anchoring tufts in and
to the backing. Many carpets also include an additional backing for
added stability. In those carpets, face yarn typically penetrates a
primary backing, as described above, and an additional backing,
such as a relatively open weave secondary backing fabric, is
secured to the stitched side with the binder. Alternative
structures in which face yarn penetrates a composite backing made
up of two or more individual components, such as superposed dual
primary backings or primary and secondary backings, also are well
known; a recent example is disclosed in International Application
WO 98/49000. In manufacture of carpets, a backing is tufted with
face yarn and the stitched side of the tufted backing is typically
coated with a liquid binder formulation capable of being cured to
form a solid binder that anchors tufts to the stitched surface or
between that surface and an additional backing. The binder, both
before and after curing, is commonly referred to as a
"backcoat."
[0004] Currently, woven polypropylene fabrics are most commonly
used as backings. Face yarns comprise a plurality of filaments and
are typically continuous multifilament yarns or spun yarns formed
by spinning staple fiber into yarn. Filaments of yarns most
commonly used as face yarn comprise synthetic resins, such as
nylon, olefin, polyester and acrylics, although natural fiber yarns
such as wool yarns are also used. Conventional backcoats used in
carpet manufacture are most commonly particulate-filled, aqueous
latexes of organic polymer compositions that set up or cure on
heating to drive off their aqueous contents. Crosslinkable
styrene-butadiene copolymers are most commonly used as the organic
polymer of the backcoat formulations. The particulate filler most
commonly is calcium carbonate and typically is present in the
latexes in significant amounts (e.g., 60-85 weight %) to impart
viscosities high enough to allow application of backcoats uniformly
over the entire surfaces of intermediate carpet structures with
simple equipment during carpet manufacture.
[0005] Although carboxylated styrene-butadiene copolymers are most
commonly used in filled latex binders due to cost and performance,
the cured binders are deficient due to their uptake of water and
tendency to lose considerable strength when wet. In finished
carpets with such binders, contact with water, for example from
spills and splashes, can lead to marked losses of tuft lock or tuft
bind such that face yarn tufts are easily pulled out of the
carpets. It has been proposed to reduce or eliminate the use of
filled, aqueous latex binders by use of binders based on
thermoplastic resins. In general, proposals of this type involve
bonding the face yarn stitches to a backing or backings by cooling
a softened or melted thermoplastic resin in contact with the
stitched side of a tufted backing and, when used, with an
additional backing, to solidify the resin. Thermoplastic resins
used for adhering the stitches and the backing are those that exist
in solid form at temperatures normally encountered during use of
carpets but can be softened or melted in contact with backings and
face yarn stitches, or softened or melted and then contacted while
softened or melted with the backings and stitches, at temperatures
low enough that the other components of the carpets are not
damaged. Thermoplastic binders comprising such resins can be
provided in solid form, such as a film or coating on or applied to
backings, as powder or loose fiber applied to the backings or
stitches, as loose fiber needled or otherwise affixed to backings,
and as fabrics secured or applied to the backings or their stitched
sides. The binders can also be provided with the resin thereof
softened or melted, for example by extruding melted resin
formulations directly onto the stitched side of a backing or by
laminating a tufted primary backing to a secondary backing with
softened or melted resin formulations applied to or between the
backings as they are brought together. Carpets made using such
binders are more resistant to loss of strength due to water uptake
than carpets with conventional, cured carboxylated
styrene-butadiene copolymer binders. Such alternative binders also
can offer advantages over conventional carpets because
thermoplastic binders are better suited for recycle to melt
processing operations than conventional binders. Thus, while face
yarns and backings most commonly used in carpets are composed
primarily of thermoplastic resins capable of being reused in
melt-forming operations, cured latex binders typically contain
levels of crosslinked polymer solids that can make such
reprocessing impractical due to burning, smoking and impairment of
flow of melted resins.
[0006] AdBac.RTM. Composite System carpets with backings made and
sold by Amoco Fabrics and Fibers Company are an example of known
carpets with thermoplastic binders. In one embodiment, AdBac.RTM.
System carpets use a light weight nonwoven web of filaments of a
thermoplastic resin needled to a woven polypropylene carpet
backing. After tufting the needled backing with face yarn, the
structure is heated to melt the resin of the filaments of the web
such that the melted resin flows around the face yarn stitches and
their junctions with the backing. The resulting structure is cooled
to solidify the melted resin, thereby anchoring the tufts and, when
a secondary backing is also used, securing it to the stitched side
of the tufted backing. Alternative AdBac.RTM. Composite System
carpets have stitches and backings adhered through use of woven
secondary backing fabrics coated with lower melting thermoplastic
resin compositions that can be melted and cooled in contact with
the stitched side of a tufted primary backing to secure the tufts
and laminate the backings. AdBac.RTM. System carpets have better
tuft lock retention when wet than conventional carpets. They also
are lighter, more flexible and easier to handle than conventional
carpets with their mineral-filled, cured latex binders and,
therefore, easier to install. They also can be installed over a
considerably broader range of temperatures and their backings and
binders afford greater potential for melt reprocessing in carpet
manufacture. Commonly assigned International Application
PCT/US96/03485 discloses carpets, backings and carpet manufacture
involving binders comprising thermoplastic resins and substantially
free of latex and mineral fillers, including AdBac.RTM. Composite
System carpets and backings and binders therefor.
[0007] Other proposals and concepts for carpets prepared using
softened or melted thermoplastic resin compositions that are cooled
in contact with face yarn stitches of a tufted backing and/or a
secondary backing to help secure tufts and/or bond primary and
secondary backings are found in commonly assigned U.S. Pat. No.
4,844,765, disclosing lamination of tufted primary carpet backings
to secondary backings with a composite hot melt adhesive sheet made
up of adhesive formulations with higher and lower melt viscosities;
U.S. Pat. No. 5,240,530, disclosing lamination of tufted primary
backings to secondary backings with a sheet of extruded isotactic
polypropylene; U.S. Pat. No. 5,532,035 disclosing tufted fabrics of
a single type of thermoplastic material in which a primary backing
of nonwoven polyester fibers and lower melting polyester binder
fibers is tufted with polyester face yarn and the tufts are
anchored and a secondary backing is laminated by partial melting of
the primary backing and then cooling the same; and European Patent
Application 80304253.0 disclosing tufted pile fabrics in which
tufts are secured to a primary backing and an anchor coat is formed
by needling or otherwise applying to both surfaces of the backing a
layer of low melting nylon or other fibers, tufting the backing
with the applied layer of fibers, and melting the layer on the side
of the backing opposite the pile surface.
[0008] A difficulty with carpets with thermoplastic binders,
however, is their tendency to fuzz during use. Fuzzing occurs when
individual filaments of yarn tufts pull completely or partially out
of the tufts and manifests itself in a fuzzy appearance and pilling
of the carpet pile and, in time, an uneven, thinning appearance.
For many types of carpets, fuzzing is encountered less frequently
and severely in carpets prepared with conventional aqueous latex
binders. The difference may be related, at least in part, to
different properties and behaviors of the softened or melted resins
of thermoplastic binders and of aqueous liquid latex formulations
as used as binders in carpet manufacture.
[0009] In the case of conventional aqueous latex binders, their
liquid nature makes uniform application easy and inexpensive. Flow
properties are easily controlled to achieve effective coating of
stitched backing surfaces and wetting of filaments of the stitches
by simple adjustment of filler, polymer and water levels of the
formulations. Unfilled or low viscosity latex formulations are
sometimes used in conjunction with conventional highly filled
formulations. In most carpet constructions and with most common
materials of construction, heating to drive off water and cure the
latex binders results in good bonding of stitches to backings and
of filaments within stitches. Surfactants can also be used to
adjust surface tensions of binder formulations in relation to tuft
stitches and backings. It also is known from U.S. Pat. No.
4,654,247 to prime face yarn stitches for application of latex
binders by applying in advance of the binder an aqueous dispersion
of surfactant or polymer with surface tension less than or equal to
that of the face yarns; the primer is reported to promote uptake of
binder by face yarns and reduce fuzzing of yarns that resist
penetration by binders due to treatments against soiling, staining,
mold, mildew and static buildup.
[0010] With thermoplastic binders, in contrast, dispersibility,
flow properties and affinity to backings and face yarns of melted
thermoplastic resins are less conducive to effective application
and bonding. In some cases, uniform application of thermoplastic
binders is hindered by their physical form. For example,
thermoplastic binders in the form of loose fiber are difficult to
apply consistently and uniformly over stitched backing surfaces;
melting and cooling of the resin of the fibers can produce
irregular gaps and thick and thin areas of binder, leaving entire
stitches or groups of stitches unbonded or only superficially
bonded. Powdered thermoplastic binders can be applied somewhat more
uniformly than loose fibers but special equipment is usually
needed. Thermoplastic films, sheets, coatings and nonwoven fabrics
tend to be more effective, not only because their sheetlike or
fabric form makes them well suited for application to the entire
stitched side of a tufted backing, but also because they can be
prepared to provide the thermoplastic binder resin in consistent
weights per unit area tailored to carpet and manufacturing
requirements. However, even the more uniformly applied
thermoplastic binders suffer due to high viscosities and poor flow
of their melted resins as compared to the liquid latex binders.
Surface tensions of the melted thermoplastic resins can also lessen
affinities to face yarns and backings and are not as easily
adjusted as those of conventional aqueous latexes. High flow rate
resins, special resin compositions, application of pressure to
intermediate carpet structures to promote flow and improve
distribution of melted resin, special application techniques and
other measures can provide improvement but not to the degree
desired and usually not without equipment modifications, added
process complexity and increased cost.
[0011] Whatever the cause or causes, fuzzing in carpets with
thermoplastic binders remains a problem and an obstacle to more
widespread realization of the benefits of such carpets. There is a
need for improvement so that filaments of face yarn tufts are more
effectively held in the carpets.
SUMMARY OF THE INVENTION
[0012] This invention provides a solution to the difficulties
described above. In one embodiment, the invention provides a
process for manufacture of tufted carpets using thermoplastic
binders in which improved bonding is achieved. In another
embodiment, the invention provides carpets with improved fuzz
resistance. In many cases, tuft lock is also improved. Such
improvements are achieved while also retaining other benefits of
carpets with thermoplastic binders, such as good retention of tuft
bind strength when wet, lighter weight, greater flexibility, easier
cold weather and cold climate installability, and greater potential
for melt reprocessibility.
[0013] Briefly, in one embodiment, the invention provides an
improvement to processes for manufacture of tufted carpets that
comprise adhering to a stitched side of a tufted backing a
plurality of stitches of face yarn comprising a plurality of
filaments by cooling in contact with the stitched side a
thermoplastic binder comprising a softened thermoplastic resin to
solidify the softened resin, wherein the improvement comprises
steps comprising applying to a plurality of stitches, before the
resin solidifies, a stitch bind composition comprising a liquid
component capable of being removed by heating at a temperature less
than the temperature at which the tufted backing is damaged by heat
and an organic polymer component capable of bonding filaments of
the stitches on removal of the liquid component; and, after
applying the stitch bind composition but before the resin
solidifies, heating the stitch bind composition to substantially
remove the liquid component without damaging the tufted
backing.
[0014] In another embodiment, the invention provides a process for
manufacture of carpets comprising the steps of providing a tufted
backing having a stitched side with a plurality of stitches of face
yarn comprising filaments, wherein filaments of a plurality of the
stitches are bonded with an organic polymer, contacting the
stitched side of the tufted backing with a thermoplastic binder
comprising a thermoplastic resin capable of being softened in
contact with the tufted backing, or of being softened and then
contacted with the tufted backing, without damaging the tufted
backing, heating the thermoplastic binder to soften the resin
without damaging the tufted backing, and cooling the backing with
softened resin in contact with the stitched side to solidify the
resin. In an alternative to this embodiment, the tufted backing
provided to the process also includes the thermoplastic binder,
thereby rendering optional the step of contacting the tufted
backing with the binder.
[0015] In another embodiment the invention provides an improvement
to processes for making carpets that include steps comprising:
[0016] providing a tufted backing comprising a backing and having a
pile side and an opposite stitched side, wherein the pile side has
a plurality of tufts of face yarn that comprise a plurality of
filaments and the stitched side has a plurality of stitches of the
face yarn; [0017] contacting the stitched side of the tufted
backing with a thermoplastic binder that comprises a thermoplastic
resin capable of being softened in contact with the tufted backing,
or of being softened and then contacted with the tufted backing,
without damaging the tufted backing; [0018] heating the
thermoplastic binder to soften the thermoplastic resin without
damaging the tufted backing; and [0019] cooling the thermoplastic
binder with the softened resin thereof in contact with at least the
stitched side of the tufted backing to solidify the thermoplastic
resin; wherein the improvement to such processes comprises steps
that comprise applying to a plurality of stitches, before the resin
solidifies, a stitch bind composition that comprises a liquid
component capable of being removed by heating at a temperature less
than a temperature at which the tufted backing is damaged by heat
and an organic polymer component capable of bonding filaments of
the stitches on removal of the liquid component; and after applying
the stitch bind composition but before the resin solidifies,
heating the stitch bind composition to remove the liquid component
without damaging the tufted backing.
[0020] In another embodiment, the invention provides a process for
making carpets comprising steps that comprise [0021] bonding to a
stitched side of a tufted backing a plurality of stitches of face
yarn comprising a plurality of filaments by cooling in contact with
the stitched side a binder comprising a softened thermoplastic
resin to solidify the resin; [0022] applying to a plurality of the
stitches, before the resin solidifies, a stitch bind composition
comprising a liquid component capable of being removed by heating
at a temperature less than a temperature at which the tufted
backing is damaged by heat and an organic polymer component capable
of bonding filaments of the stitches on removal of the liquid
component; and [0023] heating the stitch bind composition, after
application thereof to the stitches and before the resin
solidifies, at a temperature less than a temperature at which the
tufted backing is damaged by heat to remove the liquid
component.
[0024] In a further embodiment, the invention provides a process
for making a tufted carpet comprising steps that comprise [0025]
providing a tufted backing comprising a backing and face yarn
comprising a plurality of filaments, wherein face yarn penetrates
the backing and forms a pile surface comprising a plurality of
tufts on one side of the backing and a plurality of stitches on an
opposite, stitched side of the backing; [0026] applying to the
stitched side of the tufted backing and in contact with a plurality
of the stitches a stitch bind composition comprising a liquid
component capable of being removed by heating at a temperature less
than a temperature at which the tufted backing is damaged by heat
and an organic polymer component capable of bonding filaments of
the stitches on removal of the liquid component; [0027] contacting
the stitched side of the tufted backing with a binder comprising a
thermoplastic resin capable of being softened in contact with the
tufted backing, or of being softened and then contacted with the
tufted backing, without damaging the tufted backing; [0028] heating
the tufted backing in contact with the stitch bind composition to
remove the liquid component without damaging the tufted backing;
[0029] heating the binder to soften the thermoplastic resin without
damaging the tufted backing; and [0030] cooling the binder with the
softened resin thereof in contact with the stitched side of the
tufted backing to solidify the resin.
[0031] In a more specific embodiment using an additional backing
structure that is separate from the tufted backing, the invention
provides a process for manufacturing carpets comprising steps that
comprise [0032] providing a tufted primary backing having a pile
side comprising face yarn tufts and an opposite side having a
plurality of stitches of face yarn; [0033] applying to a plurality
of the stitches a stitch bind composition comprising a liquid
component capable of being removed by heating at a temperature less
than a temperature at which the tufted backing is damaged by heat
and an organic polymer component capable of bonding filaments of
the stitches on removal of the liquid component; [0034] contacting
the tufted primary backing, an additional backing and a binder
comprising a thermoplastic resin capable of being softened in
contact with the tufted backing and the additional backing, or of
being softened and then contacted with the tufted backing and the
additional backing, without damaging the tufted backing or the
additional backing, to form an intermediate structure having binder
disposed between the stitched side of the tufted primary backing
and the additional backing; [0035] heating the tufted primary
backing or the intermediate structure after application of the
stitch bind composition to remove the liquid component without
damaging the tufted primary or additional backings; [0036] heating
the binder to soften the thermoplastic resin without damaging the
tufted primary or additional backing; and [0037] cooling the
intermediate structure with the thermoplastic resin in softened
form to solidify the resin.
[0038] Another aspect of the invention provides improved carpets
prepared according to the invented process.
[0039] In yet another embodiment, the invention provides tufted
carpets comprising a backing, face yarn comprising a plurality of
filaments, an organic polymer component and a thermoplastic binder,
wherein the face yarn penetrates the backing such that a plurality
of tufts of the face yarn project from a surface of the backing and
a plurality of face yarn stitches are disposed on an opposite
surface of the backing, a plurality of filaments of the stitches
are bonded by the organic polymer component, and a plurality of
stitches are bonded to the backing with the thermoplastic binder.
In another embodiment, carpets according to the invention further
comprise an additional backing bonded to at least the stitches with
the thermoplastic binder.
[0040] The invented process is described with reference to "steps"
thereof to make clear that, except as expressed otherwise, it is
the physical manipulations or operations, without regard to timing
or sequence that make up the invented process. As will be evident
from the detailed description appearing below, except as otherwise
made clear in context, steps may be carried out together or
separately and in any sequence.
[0041] Also for purposes hereof, the expression "thermoplastic
binder" is to be understood to mean a material that comprises a
thermoplastic resin and does not contain added thermosetting,
crosslinked or crosslinkable components to an extent that destroys
or significantly reduces the resin's fundamental thermoplastic
characteristic of being or becoming plastic, or softened and
formable, on application of appropriate heat. Minor amounts of
crosslinked or crosslinkable components or moieties inherently
present in commercially available thermoplastic resins or formed
during melt processing thereof are not excluded by the expression
"thermoplastic binder", nor are such components or moieties added
to thermoplastic resins or binders for the purpose of improving
performance of the resins in melt processing. An example of the
former are gel particles, typically comprising crosslinked polymer
solids, that are normally present in minor amounts in fiber, film
and molding grade thermoplastic resins supplied by some commercial
manufacturers or that can form in minor amounts during melt
processing thereof. An example of the latter is the addition of
polyfunctional compounds, such as organic tricarboxylic acids, to
polyethylene terephthalate and other thermoplastic polyesters to
promote crosslinking to increase melt strength in melt
processing.
[0042] Except as otherwise indicated, the term "softened" when used
in reference to thermoplastic resins of the thermoplastic binders
used according to the invention means that the resin is in a
plastic state, such that it is capable of being formed and, on
cooling, will retain such form. Thus, unless context is otherwise,
the term "softened" includes resins in both heat-softened and
melted states.
[0043] The expression "osy" as used herein is an abbreviation for
"ounces per square yard." Unless indicated otherwise in context,
the term "copolymer" is used herein in a broad sense to refer to
polymers of two or more monomers. The term "suspension" is used
interchangeably with the term "dispersion" to refer to a two-phase
system having solid particles suspended or dispersed in a
continuous liquid phase. The term "emulsion" refers to a
liquid-liquid multi-phase system having a continuous liquid phase
and one or more other liquid phases dispersed therein as a
discontinuous phase. Unless stated otherwise, the abbreviation "MI"
refers to polymer melt flow rate determined according to ASTM D1238
(190.degree. C./2.16 kg) and expressed in grams per ten minutes
(g/10 min.). Also unless otherwise indicated, viscosities referred
to herein are Brookfield viscosities determined by ASTM D2196
Method A (1995) and expressed in centipoises (cps). Tuft Bind
strengths and Fuzz Ratings are determined as described in
connection with the Examples.
BRIEF DESCRIPTION OF THE DRAWING
[0044] The invention is described with reference to the drawing,
which depicts a preferred embodiment of the invented process.
DETAILED DESCRIPTION
[0045] In greater detail, the invention solves the problem of
fuzzing of carpets made with thermoplastic binders through the use
of a stitch bind composition that is applied to the yarn bundles
disposed as stitches on the stitched side of a tufted backing and
imparts improved retention of filaments and fuzz resistance to
carpets. The stitch bind composition includes a liquid component
that aids in achieving application of the composition so that it
contacts filaments of the stitches, but is easily removed during
carpet manufacture. The stitch bind composition also includes an
organic polymer component that is capable of bonding filaments of
the stitches on removal of the liquid component. The organic
polymer component is preferably used in a form that promotes its
contact with filaments of the tuft stitches. In addition to
imparting bonding of filaments in the face yarn stitches, the
organic polymer component or its residue can contribute to bonding
of tuft stitches to backing surfaces. The enhanced bonding of
filaments within stitches results in significant improvements in
fuzz resistance of carpets as compared to known carpet structures
in which tuft lock, or tuft lock and lamination of primary and
secondary backings, is accomplished using thermoplastic binders.
Surprisingly, improved fuzz resistance is achieved even in carpets
according to the invention having constructions or made from
materials such that fuzz resistance is difficult to achieve even
with conventional latex binders.
[0046] The dramatic improvements in fuzz resistance achieved
according to the invention are accomplished with surprisingly low
levels of organic polymer component. Use of the stitch bind
composition in amounts providing as little as a fraction of an
ounce of organic polymer component or residue thereof per square
yard of finished carpet can provide significant improvements in
fuzz resistance. Another advantage of the invention is the improved
tuft bind that often accompanies the improved fuzz resistance
imparted by the organic polymer component or its residue. Not only
do individual filaments of tufts resist fuzzing better than in
known carpets, other things being equal, but tufts are less prone
to being pulled out or otherwise removed from finished carpet
structures in handling, installation and use. For carpets according
to the invention, tuft bind strengths according to ASTM D1335 are
often at least about 2 pounds in cut pile carpets and at least
about 5 pounds in loop pile carpets, and preferably greater than 3
pounds and 6.25 pounds, respectively. The form and low levels of
stitch bind composition used to achieve such improvements are such
that the invented process can be implemented without complicated
and expensive equipment additions or modifications. Further,
carpets according to the invention have the water resistance
benefits of thermoplastic binders and the potential for recycle by
melt processing.
[0047] Carpets according to the invention, when constructed from
thermoplastic backings and face yarns, are advantageous by reason
of their potential for reuse in plastics reprocessing operations.
As noted above, use of thermoplastic binders, as opposed to
conventional latexes, avoids the crosslinked latex particles that
typically result from curing conventional latexes and, in turn,
difficulties they cause in attempts to reprocess the same in melt
fabrication processes. Consequently, not only trim and waste from
carpet manufacturing operations, but even post-consumer carpet are
more easily used in recycle operations in which plastic waste is
reduced to a form and size suitable for use in extrusion, molding,
spinning or other melt processing operations and so-processed
either alone or blended with virgin or other plastics recycle
streams. Preferred organic polymer components of the invented
carpets are processible with plastics from backings, face yarns and
thermoplastic binders in melt reprocessing operations, and even in
the case of organic polymer compositions normally considered
incompatible or ill-suited for such operations, the levels used or
present for achieving improved fuzz resistance are often low enough
that they do not impair reprocessing. The invented carpets and
process also afford opportunities for avoiding the expense of
recycle operations in which pile surfaces are sheared to remove
face yarn tufts for reuse of the plastics thereof, and for disposal
of backings and binders through use in melt reprocessing operations
even when pile surfaces are sheared.
[0048] The benefits of the invented carpets provide opportunities
to expand utility of carpets with thermoplastic binders to a
broader range of applications, many of which have been considered
beyond the reach of such carpets due to their demanding
requirements. Specific examples include commercial carpets, such as
are used in office buildings, airports, schools and the like, and
hospitality carpets, such as hotel and motel carpeting, all of
which are subject to heavy wear due to extensive and rigorous
traffic, frequent cleaning and sometimes careless or inattentive
use. Benefits of the invention can be realized over the entire life
of a carpet, including greater potential for reuse of carpet
materials during manufacture, easier and less labor-intensive
installation due to the carpets' lower weights, expanded cold
weather and cold climate installability due to their greater
flexibility, better appearance during use and longer useful life
due to reduced fuzzing and retention of tuft lock when exposed to
water, and the potential for melt reprocessing instead of disposal
at the end of the carpet's life.
[0049] As described above, in one of its aspects the invention
provides a process for manufacture of carpets using thermoplastic
binders to anchor tufts of face yarn to or between backings wherein
improved retention of filaments of the tufts is achieved through
use of a stitch bind composition that is applied to the stitches of
a tufted backing and bonds filaments of a plurality of stitches so
that they are more resistant to being removed from the tufts that
form the carpet pile. The process and the improved carpet
performance it provides are broadly applicable in manufacture of
carpets in which stitches of face yarn are anchored to a backing or
between backings by cooling a thermoplastic binder comprising
softened or melted thermoplastic resin in contact with the stitched
side of a tufted backing or between such a stitched side and an
additional backing. Such processes can vary considerably in their
specific aspects but they preferably comprise basic steps that
involve providing a tufted backing having a pile side comprising
face yarn tufts and a stitched side having face yarn stitches,
contacting the stitched side of the tufted backing with a
thermoplastic binder comprising a thermoplastic resin capable of
being softened in contact with the tufted backing, or of being
softened and then contacted with the tufted backing, without damage
to the tufted backing, heating the thermoplastic binder to soften
the resin without damaging the tufted backing, and cooling the
binder with the softened resin thereof in contact with the stitched
side of the tufted backing to solidify the resin. When an
additional backing is to be bonded to the stitched side of the
tufted backing in such processes, the processes include a step in
which the additional backing, thermoplastic binder and tufted
backing are contacted to form an intermediate structure in which
the binder is disposed between the stitched side of the tufted
backing and the additional backing, and a step in which the
intermediate structure with the thermoplastic resin of the
thermoplastic binder in softened form is cooled to solidify the
resin. The improvements according to the present invention result
from including in such processes, before the softened resin of the
thermoplastic binder solidifies, steps comprising applying to a
plurality of the stitches a stitch bind composition comprising an
organic polymer component capable of bonding filaments of the
stitches and a liquid carrier for the organic polymer component
that can be removed by heating without damaging the tufted backing,
and heating the stitch bind composition, after application thereof,
to remove the liquid component without damaging the tufted
backing.
[0050] Thus, in some of its embodiments, the process according to
the invention may be considered an improvement that is applicable
to a wide range of processes for carpet manufacture utilizing
thermoplastic binders. In other embodiments, the invention resides
in processes for manufacture of carpets in which particular steps
or aspects or combinations thereof provide new and improved
results. The drawing illustrates an embodiment of a process
according to the invention. While the process is susceptible,
without departing from the scope of the invention, to variation in
its steps, their sequence, materials used therein and in other
respects, the drawing and the following description thereof will
contribute to understanding of both the particular embodiment
exemplified in the drawing and of various broader aspects of the
invention.
[0051] In the process illustrated in the drawing, stitch bind
composition is applied to a stitched side of a tufted backing, the
backing with applied stitch bind composition is heated to remove
the liquid component, the result is contacted with a thermoplastic
binder and then heated to soften or melt the resin of the binder,
and the stitched side of the backing in contact with the softened
or melted resin of the binder is cooled to solidify the resin.
Referring to the drawing, tufted backing 1, comprising a backing
having a pile formed from face yarn tufts extending therefrom on
pile side 3 and face yarn stitches disposed on an opposite,
stitched side 2 is unwound from roll 10. The tufted backing, with
its stitched side up and pile side down, is advanced past
applicator 12 at which stitch bind composition 5, in liquid form,
is applied to the stitched side into contact with a plurality of
stitches across the width of the tufted backing. Applicator 12 has
spray heads 14 configured to apply a spray to the stitched side
across its width as the tufted backing advances. The applicator
includes a reservoir and associated controls, pump and transfer
lines (not shown) for holding the stitch bind composition and
delivering it to the nozzles under pressure adequate to form a
spray. The stitch bind composition is a solution, suspension or
emulsion comprising organic polymer and liquid components. The
composition is formulated with a viscosity effective for coating or
penetrating the stitches and organic polymer content effective for
bonding filaments of the stitches after the liquid component is
removed.
[0052] The tufted backing with stitch bind composition applied to
its stitched side is passed to oven 20. During passage through the
oven, the backing with applied stitch bind composition is heated to
drive off the liquid of the stitch bind composition, leaving the
organic polymer component or a residue thereof that bonds filaments
of the stitches. Heating is conducted at a temperature and for a
time sufficient for substantial removal of the liquid of the stitch
bind composition but without damaging the tufted backing. Vapors of
the liquid component are removed from the oven by a suitable vent
or exhaust system (not shown).
[0053] From oven 20, the tufted backing with organic polymer
component or residue bonding filaments of a plurality of the
stitches is conveyed to roll 22 at which it is brought into contact
with thermoplastic binder 7. In the embodiment of the invention
illustrated in the drawing, the thermoplastic binder is in
sheet-like form, such as a film or a nonwoven fabric comprising a
thermoplastic resin that softens or melts at a temperature below
the temperature at which the tufted backing is damaged by heat. The
binder is supplied from roll 24 over guide roll 26 and into contact
with the stitched side of the tufted backing at roll 22. It will be
appreciated that the equipment configuration illustrated in the
drawing is also suitable for use of other thermoplastic binders
that can be supplied from a roll, such as other fibrous webs or
assemblies or additional backings that include or incorporate a
thermoplastic binder.
[0054] The tufted backing with its stitched side in contact with
the binder is then passed to oven 28 in which the assembly is
heated at a temperature and for a time such that the resin of the
thermoplastic binder softens or melts without damage to the backing
or face yarn. From oven 28, the assembly with softened or melted
thermoplastic resin is passed through nip roll system 30. The nip
roll assembly is located near enough the exit of the oven that the
resin of the thermoplastic binder is still in a softened or melted
state when the assembly passes through the nip. Application of
force during passage through the nip between the rolls compresses
the resin into and around the tuft stitches, thereby promoting more
uniform distribution of softened or melted resin throughout the
structure. The resulting assembly cools after leaving the nip roll
system and the softened or melted resin solidifies. The resulting
carpet structure is then collected on takeup roll 32.
[0055] The invention is not to be considered limited to the
preferred embodiments, materials, equipment configurations or other
features depicted in the drawing or described above. While the
process and equipment configuration illustrated in the drawing uses
thermoplastic binder supplied from a roll, it will be appreciated
that when binders in other forms are used, the illustrated binder
supply and guide rolls can be eliminated and suitable alternative
feeding devices, such as hoppers, extruders, and other solids and
liquids feeders, can be added. Other equipment illustrated in the
FIGURE can also be varied. Belt and screen conveyors are suitable
alternatives to the various feed and guide rolls depicted in the
drawing. Hot air and forced air ovens are well suited for heating
the various intermediate structures; however, other suitable
equipment such as heated rolls, electric and infrared heaters and
other suitable means can be utilized provided heat transfer
capabilities are adequate to achieve suitable temperatures and
dwell times.
[0056] In a variation of the process illustrated in the drawing,
the tufted backing has a thermoplastic binder included or
incorporated therein, such that a separate step for contacting the
binder and the stitched side of the backing can be eliminated or
employed to contact additional binder or a binder in different form
with the backing. Another variation of the process comprises
contacting the stitched side of the tufted backing, thermoplastic
binder and an additional backing to form an intermediate structure
with the binder disposed between the stitched side and the
additional backing; heating the binder to soften the resin thereof
and cooling the intermediate structure to solidify the softened
resin results in a carpet structure having stitches anchored
between the backings by the solidified resin. In such processes,
either or both of the tufted backing and the additional backing can
include or incorporate a thermoplastic binder. Thus, referring
again to the drawing, an additional backing, such as a secondary
backing, having a coating of suitably low softening thermoplastic
resin formulation or a nonwoven web of filaments of such a resin
formulation needled thereto, can be supplied from roll 24 into
contact with stitched side of tufted backing at roll 22. The
resulting intermediate structure advances to oven 28 where it is
heated to soften the resin of the binder, again without damaging
the backings or face yarn, and then to the nip roll assembly and is
taken up after cooling to solidify the resin of the binder.
[0057] In another preferred embodiment of the process, the tufted
backing is provided with filaments of its stitches already bonded
by an organic polymer or residue thereof. In such an embodiment,
steps of the process comprise contacting the tufted backing with a
thermoplastic binder, heating the thermoplastic binder to soften
the resin thereof and cooling the softened resin to solidify the
resin in contact with the stitched side of the tufted backing. The
tufted backing provided to such a process can also include or have
incorporated into the backing thereof a thermoplastic binder, in
which case steps of the process comprise heating the binder to
soften the resin thereof and cooling the softened resin to solidify
the same in contact with the stitched side of the tufted
backing.
[0058] Irrespective of particular steps and combinations thereof
used in the invented process, preferred materials used therein
include tufted backings in which the backing comprises a woven
polypropylene fabric and the face yarns comprise filaments of
polypropylene, polyester or nylon. More preferably, the backing is
a plain weave fabric woven from polypropylene tapes. Carpet yarns
are more preferably continuous multifilament yarns and spun yarns,
which typically are textured or bulked, such as by one or more of
entanglement, crimping, twisting, cabling, and also can be heat set
to improve retention of texture.
[0059] Preferred thermoplastic binders are films, coatings and
nonwoven fabrics, including continuous filament nonwovens, such as
spunbonded and centrifugally spun webs, and staple fiber webs, such
as needlepunched, thermal bonded and carded webs. Such binders more
preferably have weights of about 1 to about 15 osy. The
thermoplastic resins of the binders melt at temperatures above
about 50.degree. C., and preferably above about 60.degree. C.,
because lower melting resins may not withstand heat encountered in
use of final carpets. In processes in which a thermoplastic binder
is contacted with a tufted backing with the resin of the binder in
solid form and then heated in contact with the backing to soften
the resin, the resin of such binders preferably softens at about
100 to about 145.degree. C. In processes in which softening or
melting of the resin of a thermoplastic binder precedes contacting
of the binder and a tufted backing, higher melting resins are
suitable provided they can be contacted with the tufted backing and
any additional backings that are used with the resin in softened or
melted form without damage to the tufted and other backings. In
either case, thermoplastic resins comprising at least one
polyolefin homopolymer or copolymer resin that softens within a
suitable temperature range are particularly useful. Particularly
preferred resins include polyethylene resins (including high, low
and linear low density resins and so-called metallocene
polyethylenes), polypropylene resins (including metallocene
polypropylenes), copolymers of ethylene and propylene, optionally
with other monomers (including both ethylene and propylene
dominated copolymers, block, random and segmented copolymers and
elastomeric and thermoplastic-elastomer copolymer resins), and
combinations of such resins or comprising one or more such resin
and one or more other resins.
[0060] Additional backings, when used, preferably are polypropylene
fabrics, including those woven in close or relatively open or
coarse weaves, and nonwoven fabrics comprising polypropylene or
polyester filaments. More preferably, woven backings are woven from
tapes in one direction and spun or continuous filament yarns in the
other direction in a plain or leno weave.
[0061] Preferred backings, for either or both of the backing that
is tufted and additional backing, when used, also include such
backings that include or have incorporated a thermoplastic binder.
Backing-binder composites comprising thermoplastic binder at one or
both surfaces in the form of an adhered layer comprising a suitably
low softening point thermoplastic resin or an affixed nonwoven
fabric having filaments comprising such a resin are particularly
suitable. Backings coated with a layer comprising the thermoplastic
resin or having needled or thermally bonded nonwoven webs of
filaments comprising the resin are most preferred.
[0062] The stitch bind composition is most preferably a dispersion
or emulsion of organic polymer having a viscosity of about 1.5 to
about 400 centipoises and organic polymer content of about 5 to
about 25 weight %. Particularly preferred stitch bind compositions
comprise stable aqueous dispersions and emulsions of organic
film-forming polymers, and particularly film forming
olefin-unsaturated acid, -unsaturated acid ester and -diene
copolymers. Specific examples include film-forming ethylene acrylic
acid copolymers, styrene acrylate copolymers and styrene butadiene
copolymers.
[0063] When using the preferred materials described above,
preferred operating conditions for the invented process include use
of the stitch bind composition in amounts effective to provide
about 0.25 to about 2 osy of organic polymer to the stitched side
of the tufted backing, heating at about 105 to about 140.degree. C.
to remove the liquid of the stitch bind composition, use of
thermoplastic binder in amounts providing about 2 to about 12 osy
in finished carpets, heating at about 105 to about 150.degree. C.
to soften or melt the resin of the binder without damaging the
tufted backing or additional backings that may be used, and, when
force is applied to promote flow or distribution of softened or
melted resin of the thermoplastic binder, force of about 10 to
about 70 pounds per linear inch.
[0064] While the invented process has been described above in
reference to various steps, compositions, constructions and other
features and aspects reflecting operational, materials and finished
product preferences, the invention contemplates not only broader
applicability to manufacture of carpets using thermoplastic binders
but also considerable variation in both its broad and more specific
aspects, including its steps, combinations and operational aspects
thereof, choices of materials used therein, features of products
thereof and in other respects. Broader aspects of the invented
process are discussed below.
[0065] Generally, the stitch bind composition used according to the
invention comprises an organic polymer component that is capable of
bonding filaments of the face yarn stitches, and a liquid component
that serves as a carrier for the organic polymer and is capable of
being removed by heating at a temperature below that at which the
tufted backing is damaged by heat. The liquid form of the stitch
bind composition facilitates application thereof to the stitched
side of the tufted backing so that it contacts a plurality of
stitches thereof. The composition as used in the process preferably
has viscosities suited to coating or penetrating yarn bundles
disposed as stitches on the stitched side of tufted backings so
that it contacts filaments thereof.
[0066] The composition is conveniently used as a dispersion,
emulsion or solution of the organic polymer component in the liquid
component, and preferably has a viscosity of about 0.5 to about
3000 centipoises to afford good coating of stitches. More
preferably, viscosity is about 1 to about 1200 centipoises, with
about 1.5 to about 400 centipoises being most preferred. It is also
preferred that the organic polymer content of the stitch bind
composition, whether dissolved, suspended or emulsified, be at
least about 5 weight %; at lower levels, volumes of stitch bind
composition containing adequate organic polymer for effective
bonding of filaments can require handling and removal of excessive
amounts of liquid component. More preferably, organic polymer
contents are about 5 to about 60 weight %. Higher levels can lead
to viscosities not conducive to efficient application of the
composition and effective penetration of the filament bundles
making up the stitches. It also is beneficial for process
efficiency to use stable dispersions or emulsions of organic
polymer component in the liquid component. As is known, stability
of dispersions and emulsions is influenced by factors such as
composition and particle size of dispersed or emulsified particles,
ionic or polar character of the particles, composition and
properties of the liquid component of the system and presence of
other components. While the range of factors and complexity of
their interrelationships make quantitative characterization of
stability difficult, it is adequate for purposes of the invention
to characterize preferred stitch bind compositions as stable
dispersions, emulsions and solutions with suitable viscosities and
organic polymer contents. For purposes hereof, the term "stable",
when used in reference to a dispersion or emulsion, means that the
dispersion or emulsion retains its two-phase character of
relatively small particles or droplets of organic polymer component
distributed essentially uniformly in a liquid medium, or, when used
in reference to a solution, that the solution retains its one phase
character, for a prolonged period of time at temperatures
convenient for handling and use of the same according to the
invented process, for example at a temperature within the range of
about 5 to about 60.degree. C. for a period of one or more days.
Stable dispersions and emulsions of organic polymer in suitable
liquids with organic polymer contents of about 10 to about 40
weight % and viscosities described above, and especially about 1.5
to about 175 cps are particularly preferred.
[0067] The organic polymer component of the stitch bind composition
is a material that, on removal of the liquid component, bonds
filaments of the stitches. Such bonding of filaments of the
stitches may be provided by the organic polymer component as such
or by a residue resulting from reaction of the organic polymer
component, or reaction thereof with other components of the stitch
bind composition, on removal of the liquid component. The organic
polymer or its residue bonds filaments of the stitches in the sense
that it encapsulates or agglomerates between or around filaments of
the stitches with sufficient strength to make filaments of the
tufts more resistant to being removed. Film-forming organic
polymers generally have adequate strength for such purposes and are
preferred materials for the organic polymer of the stitch bind
composition. As is known, film-forming characteristics of a polymer
are a function of a number of properties and interrelationships,
including composition, polymer chain flexibility and molecular
weight, and interactions with particular substrates to which it is
applied.
[0068] Preferred organic polymer components also are compositions
that can be formulated with a suitably low boiling liquid component
to provide dispersions, emulsions or solutions having the preferred
organic polymer contents and viscosities described above with
respect to the stitch bind composition. Polymers capable of forming
stable aqueous dispersions or emulsions are particularly preferred
due to the inert nature of water relative to other carpet
components and the relatively low temperatures that can be used for
heating to remove the same in the process. Water-soluble polymers,
while effective for imparting fuzz resistance, are less preferred
than water-based suspensions and emulsions because in finished
carpets, water-solubility can lead to loss of fuzz resistance due
to contact with water such as from spills, splashes and cleaning.
Preferred organic polymers also are compositions that are swelled
by not more than about 20% of their weight in contact with water at
room temperature. Higher levels of moisture uptake by the polymer
may affect its ability to bond filaments and, in finished carpets,
may also diminish tuft bind strength.
[0069] Natural and synthetic organic polymers are suitable for use
according to the invention. The term "organic polymer" is used in a
broad sense to mean any polymeric or oligomeric material in which
the repeat units of the polymer or oligomer chain comprise one or
more carbon atoms to which is bonded one or more hydrogen atoms.
Synthetic polymers are preferred due to their generally greater
resistance to biodegradability than natural materials. Suitable
synthetic polymers include thermoplastic polymers as well as
crosslinking polymers that set up or cure into rubbery or
intractable solids on heating and/or removal of the liquid
component of the stitch bind composition. Thermoplastic materials
are preferred for their greater processibility with other materials
in melt reprocessing carpet manufacturing scrap and waste as well
as spent carpets. Preferred thermoplastic polymers melt at
temperatures above about 50.degree. C., and more preferably between
about 60 and about 140.degree. C. Lower melting polymers can soften
at temperatures close to those experienced in use of carpets, to
the detriment of fuzz resistance. Higher melting polymers are
useful, particularly when backings and face yarns are composed of
suitably high softening point polymer components or other materials
that can withstand the melting temperatures; however, backings most
commonly used are composed of polypropylene resins, which melt at
about 168.degree. C., and accordingly, organic polymers with
melting points up to about 140.degree. C. are most useful because
softening or melting thereof during heating to remove the liquid
component of the stitch bind composition can result in flow or
deformation of the polymer so that it better contacts or
encapsulates filaments of the stitches.
[0070] Examples of polymers suitable as the organic polymer
component of the liquid stitch bind composition include the
thermoplastic and/or crosslinkable olefin-acid, -ester and -diene
copolymers described above, specific examples of which include
those previously identified and ethylene vinyl acetate copolymers,
styrene-acrylate-acrylonitrile copolymers and vinyl chloride
acrylic acid copolymers. Other thermoplastic olefinic polymers,
including copolymers, are also suitable as are urethane polymers.
Specific examples include vinyl chloride and vinylidene chloride
polymers, maleated and other acid-grafted polyethylenes and
polypropylenes and aliphatic urethanes. Examples of crosslinkable
organic polymers suitable as the organic polymer component include
styrene acrylate copolymers, carboxylated styrene butadiene
copolymers, carboxylated and other crosslinking or crosslinkable
acrylic polymers and crosslinkable ethylene vinyl acetate
copolymers. As is known, crosslinkable polymers can be made
crosslinking by addition of suitable crosslinking agents for the
polymers. Examples of typical carboxyl-reactive crosslinking agents
include melamine-formaldehyde resins, phenol-formaldehyde resins,
epoxy resins, zinc complexes, polyamines and urea-formaldehyde
resins.
[0071] Particularly preferred organic polymers used as components
of the stitch bind compositions are ethylene-acrylic acid
copolymers, styrene-acrylate copolymers,
styrene-acrylate-acrylonitrile copolymers and carboxylated
styrene-butadiene copolymers. Among these, the ethylene acrylic
acid copolymers, and particularly those with about 10 to about 30
wt % ethylene units are preferred thermoplastic organic polymers
due to their good aqueous dispersibility at effective polymer
contents and viscosities and excellent filament bonding
capabilities with a wide range of face yarn compositions and
configurations. These preferred polymers are most preferably used
in the form of stable aqueous dispersions or emulsions having
viscosities of about 1 to about 500 cps and organic polymer
contents of about 5 to about 40 weight %, and most preferably with
viscosities of about 1.2 to about 400 cps and organic polymer
contents of about 10 to about 25 wt %.
[0072] The liquid component of the stitch bind composition is a
liquid in which the organic polymer can be dispersed, emulsified or
dissolved and which boils or vaporizes at a temperature such that
it can be removed by heating at a temperature below that at which
the other carpet materials used in the process are damaged by heat.
As noted above, aqueous liquid components are most preferred
because water is easily removed at temperatures well below those at
which carpet components are damaged by heat and is a good medium
for dispersion and emulsification of many suitable organic
polymers. While aqueous liquid components have significant
practical advantages, other suitably performing liquids include low
boiling alcohols, ketones and halogenated hydrocarbons. Preferably,
the liquid component is one that can be removed at temperatures not
greater than about 140.degree. C. to provide a safety margin
against damaging backings and face yarn during removal of the
component.
[0073] The stitch bind composition can also contain stabilizers,
dispersing aids, thickeners, plasticizers, crosslinking agents,
surfactants and other additives if desired. Inclusion of thickening
agents can be beneficial for adjusting viscosities of stitch bind
compositions to desired levels. As described above, crosslinking
agents can be added to stitch bind compositions in which a
crosslinkable organic polymer is present to provide a crosslinking
organic polymer component. Application of stitch bind composition
by foam and froth application techniques can benefit from inclusion
in the compositions of surfactants to assist in forming and
maintaining foams and froths for process use; however, use of too
much surfactant can be detrimental to fuzz resistance due to
increased moisture uptake often imparted by surfactants.
[0074] While suitable stitch bind compositions can be formulated
from organic polymer and liquid components and other components as
desired, a variety of commercially available dispersions, emulsions
and other materials can be used as, or to prepare, suitable
compositions. Specific examples of commercially available materials
include aqueous styrene acrylate copolymer emulsions such as those
available from Rohm and Haas Company under the Rhoplex.RTM. name,
styrene acrylate copolymer formulations, acrylic
acid-styrene-acrylonitrile formulations and self-crosslinking
carboxylated styrene-butadiene copolymer emulsions known as
Acronal.RTM. and Styrofan.RTM., respectively, from BASF, aqueous
ethylene-acrylic acid copolymer formulations available from
Michelman Corp. under the Michem.RTM. trademark, self-crosslinking
acrylic polymer and ethylene-vinyl acetate emulsions sold under
National Starch and Chemical Company's Nacrylic.RTM. and
Dur-O-Set.RTM. names, aqueous, anionic emulsions of acrylic
polymers such as Hycar.RTM. Acrylic Emulsions from BFGoodrich,
aqueous anionic emulsions of crosslinking or carboxylated vinyl
chloride acrylic copolymers such as Vycar.TM. PVC Emulsions from
BFGoodrich, crosslinking and carboxylated styrene-butadiene
copolymer emulsions such as Good-rite.RTM. Styrene-Butadiene
Emulsions from BFGoodrich and aqueous aliphatic urethane
formulations such as Sancure.RTM. Waterborne Aliphatic Urethane
Polymers from BFGoodrich. Many of these materials are available as
stable, 30 to 50 wt % polymer content formulations with viscosities
generally in the range of about 30 to about 1000 cps and can be
adjusted to polymer contents, viscosities and otherwise as desired
for process use.
[0075] In the invented process, the stitch bind composition is
applied to the stitched side of the tufted backing. It is applied
to substantially the entire stitched side so that it contacts all
or at least a substantial portion of the stitches. The stitch bind
composition is applied in an amount such that sufficient organic
polymer is delivered to the stitches so that on heating to remove
the liquid of the binder, effective bonding of filaments of the
stitches by the organic polymer component or its residue is
achieved. Surprisingly low levels of the organic polymer component
or its residue provide significant bonding of filaments and,
frequently, increased tuft bind strength. Further increases in tuft
bind strength often are achieved at higher levels. Particular
amounts for a given application will vary somewhat depending on
choice of the stitch bind composition and characteristics and
composition of the components of the tufted backing. Generally,
greater amounts of organic polymer give better results when face
yarns of the tufted backing have greater yarn deniers or tighter or
more compact structure, such as in cabled and twisted yarns, those
with low bulk levels and with relatively small and tight yarn
bundles often found in wool carpet face yarns. Greater amounts also
are beneficial with tufting patterns having higher numbers of
stitches per unit area or complex stitch patterns such as the
stepover stitches commonly used in patterned and multi-level pile
constructions.
[0076] Preferred amounts of organic polymer useful for a wide range
of stitch bind compositions over a broad spectrum of carpet and
face yarn choices are about 0.2 to about 3 osy, with about 0.3 to
about 1.5 osy being preferred for typical velvet and plush carpet
styles with face yarns having yarn deniers up to about 5000 and
about 0.5 to about 2 osy preferred for heavier yarns and in carpet
constructions with high stitch levels, stitch patterns with
significant stepovers or overlap of stitches or otherwise having
significant amounts of face yarn present on the stitched side of
the tufted backing. It will be appreciated that the amounts of
organic polymer component described above are expressed in weights
of solid polymer applied to the stitched side of backings and that
amounts of stitch bind composition applied to stitched sides of
backings to provide such amounts of organic polymer and application
rates will be determined based on organic polymer contents of the
compositions and relevant process parameters such as the particular
technique by which the composition is applied and line speeds.
[0077] The stitch bind composition can be applied to the stitched
backing surface by any means suitable for effective application.
Examples include application by spraying, as a froth or foam and
with kiss roll or dip bath systems. The application system should
be configured in relation to line speeds and widths and
characteristics of the stitch bind composition to deliver the
composition at rates effective to achieve the application amounts
described above. For preferred stitch bind compositions having
viscosities of about 1 to about 400 cps, application by spraying is
convenient and provides good control over amounts applied. Spraying
is conveniently accomplished using one or more spray nozzles
configured to deliver a spray of effective volumes of the
composition to the stitched side of a tufted backing. Most
preferably, the stitch bind composition is sprayed from one or more
nozzles disposed across the width, of the carpet manufacturing line
with the spray directed downward toward the stitched side of the
tufted backing as it advances horizontally through the process
line. Spray patterns are most preferably overlapped to account for
typical reductions in volume and increasingly diffuse delivery of
spray as distance from the center of the patterns increases.
[0078] After application of the stitch bind composition, but before
softened resin of the thermoplastic binder solidifies in contact
with the stitched side of the tufted backing, the stitched side
with the liquid composition applied thereto is heated to remove the
liquid component. This heating can take place in the same step as
heating to soften the resin of the thermoplastic binder if desired
or it can be conducted in a separate step. Heating is conducted at
a temperature and for a time effective to drive off the liquid
component of the stitch bind composition without damaging the
tufted backing. Such damage can include melting or undesirable
softening of the backing or face yarns, loss of face yarn bulk,
development of a crispy or harsh-texture in the face yarn tufts and
curling, loss of strength or other undesirable effects on backings.
Preferably, heating to remove the liquid component is such that the
tufted backing does not reach temperatures higher than about
10.degree. C. below the thermal damage temperature of the backing
and face yarn, and more preferably at about 20.degree. C. or more
below such temperature. As will be appreciated, depending on the
nature of the heating means employed and product characteristics,
temperature settings of heating devices may exceed the temperature
at which a particular tufted backing is damaged because factors
such as heat transfer or dwell time in the device are such that
damage to the tufted backing does not occur even at the higher
temperature setting.
[0079] Specific temperatures and times for heating to remove the
liquid component will depend on particular choices of materials and
on equipment capabilities and configuration. For manufacture of
carpets from commonly used materials of construction, heating is
preferably conducted such that temperature of the tufted backing
does not exceed about 150.degree. C. and is more preferably about
140.degree. C. Dwell times at the heating temperatures depend on
temperature, nature and heat transfer capabilities of the heating
means and mass of the carpet to be heated, and typically range from
several seconds to several minutes. For carpets made from common
materials of construction, aqueous stitch bind compositions in
which polymer contents are about 5 to about 60 wt % and heating
using circulating air ovens of the type generally employed in
carpet manufacture, dwell times of about 0.2 to about 5 minutes are
generally adequate for removal of liquid component. When heating to
remove the liquid component and heating to soften the resin of a
thermoplastic binder are conducted in the same step, temperatures
and/or dwell times to soften the resin are typically adequate or
more than adequate for removal of the liquid component.
[0080] As described above, the steps of applying stitch bind
composition to a stitched side of a tufted backing and heating to
remove the liquid component of the composition can be conducted as
part of or in conjunction with manufacture of carpets using
thermoplastic binders in which stitches of face yarn are anchored
to a backing or between backings by cooling a softened
thermoplastic resin in contact with a tufted backing surface or
between backings to solidify the softened resin. Preferred carpet
manufacturing processes using thermoplastic binders include as
basic steps providing a tufted backing; contacting a stitched side
of the tufted backing with a thermoplastic binder that comprises a
thermoplastic resin capable of being softened in contact with the
tufted backing, or of being softened and then contacted with the
tufted backing, without damaging the tufted backing; heating the
thermoplastic binder to soften the thermoplastic resin without
damaging the tufted backing; and cooling the thermoplastic binder
with the softened resin thereof in contact with at least the
stitched side of the tufted backing to solidify the thermoplastic
resin. Such steps are described in greater detail below.
[0081] One step comprises providing a tufted backing. The tufted
backing comprises a backing and has a pile side and an opposite
stitched side. The backing can be a single structure or it can be a
composite comprising two or more individual backings or components.
The pile side of the tufted backing is made up of tufts of face
yarn that comprises a plurality of filaments. The stitched side has
a plurality of stitches of the face yarn. The tufted backing can be
provided by any suitable means. It can be made in a separate
operation and provided to the process as a pre-formed structure,
for example from rolls or other suitable sources of supply.
Alternatively, formation of a tufted backing can be integrated with
other steps so that the tufted backing is formed in-line and fed
directly to one or more other steps. When pre-formed, the tufted
backings are most conveniently provided from a roll.
[0082] Whether formed in a separate step or in-line, tufted
backings are most commonly formed by advancing a backing through a
tufting machine. Tufting machines typically have a plurality of
reciprocating needles disposed so that they can be inserted into
and retracted from a backing across its width as it advances
through the machine. In use, the needles are threaded with face
yarn and their reciprocating action together with advancement of
the backing causes the needles to continuously penetrate through
and out of the backing along the length thereof. The yarns with
which the needles are threaded penetrate through and out of the
backing, thereby forming a plurality of tufts on one side of the
backing and a plurality of stitches on the opposite side. Tufts can
be cut, typically by action of cutting blades acting in association
with the tufting needles, to form so-called cut-pile carpets, or
they can be left uncut to form so-called loop pile carpets. Needle
spacing, distance of the needle stroke and speed of the backing
through the machine can be varied to provide desired levels of tuft
or pile density and pile height. Complex and patterned pile
surfaces can be formed through use of different yarns, variations
in needles, needle patterns or tufting parameters or other suitable
means as known to those skilled in the tufting arts.
[0083] The backing used to form the tufted backing can include or
incorporate a thermoplastic binder if desired. Thus, the backing
can include or have needled, thermally bonded or otherwise secured
to at least one surface thereof fibers or a fibrous assembly, such
as a nonwoven web or loosely woven scrim, comprising a
thermoplastic resin that softens or melts at a lower temperature
than that at which the tufted backing is damaged by heat. Binder
can also be included or incorporated in the backing to be tufted by
coating or laminating to one or both backing surfaces a layer
comprising such a thermoplastic resin. Such backings are best
suited for use in manufacture of carpets in which the backing of
the tufted backing is the only backing included in the carpets or
in which an additional backing is secured to the stitched side of a
tufted backing with thermoplastic binder in addition to that
incorporated into the tufted backing.
[0084] The tufted backing can also be subjected to various
intermediate finishing steps before use in the invented process. As
noted above, tufts can be cut to form a cut pile. When face yarn of
the tufted backing lacks desired coloration, as is often the case
with nylon yarns, piece dying or continuous dying of the tufted
backing can be conducted. Other examples include topical treatments
with or applications of stain resisting agents, mold and mildew
preventatives and combinations thereof. Generally, any such
intermediate treatments can be performed provided they do not
introduce into the tufted backing materials that will not withstand
temperatures encountered during subsequent contact between the
tufted backing and the softened resin of the thermoplastic binder.
As with manufacture of the tufted backing, intermediate finishing
steps can be performed separately from the invented process or they
can be integrated into the same.
[0085] In embodiments of such processes in which preparation of a
tufted backing is conducted in a separate operation from softening
and cooling the resin of the thermoplastic binder, stitch bind
composition can be applied and the liquid component removed
therefrom as part of or in conjunction with preparation of the
tufted backing. In such cases, the tufted backing provided to
subsequent operations involving heating a thermoplastic binder and
cooling softened resin thereof to solidify the same is a tufted
backing having filaments of a plurality of the stitches thereof
adhered with an organic polymer component or residue thereof.
[0086] Another step of processes using thermoplastic binders
comprises contacting the stitched side of the tufted backing with a
thermoplastic binder comprising a thermoplastic resin capable of
being softened in contact with the tufted backing, or of being
softened and then contacted with the tufted backing, without
damaging the tufted backing. Contact can be accomplished by any
suitable means, in a separate step or in the same step as other
process steps, and with the binder in any suitable form, including
solid form, with the resin of the binder softened or melted or
combinations thereof. Contacting the stitched side of the tufted
backing with the binder can occur at any of the structure on the
stitched side of the backing, for example at one or more of the
surfaces thereof formed by the stitches, between the backing and
the backs of the stitches and between stitches.
[0087] In greater detail, the binder can be contacted with the
stitched side of the tufted backing in solid form, such as a
powder, pellets, granules or flakes of a thermoplastic resin
formulation, fibers comprising the thermoplastic resin, nonwoven
fabrics, scrims and other fibrous assemblies comprising filaments
of resin formulation, films or sheets comprising the thermoplastic
resin, layers or coatings comprising thermoplastic resin coated
onto or applied to a backing or stitched side of a tufted backing,
and fibers or any of the aforementioned fibrous assemblies secured
to a backing such as by needling, thermal bonding, with adhesives
or by other suitable means. It will be appreciated that when
thermoplastic binder is incorporated into a backing that is
subsequently tufted, contacting the binder and the stitched side
occurs on tufting of the backing. The binder can also be contacted
with the stitched side with the thermoplastic resin of the binder
in softened or melted form, such as by extruding, coating or
otherwise applying softened or melted resin to the backing or
spinning melted or softened fibers directly onto a backing. Binders
in more than one form and/or of one or more composition can be
used.
[0088] With the wide range of forms in which the thermoplastic
binder can be used, it will be appreciated that a wide range of
techniques can be used for contacting the stitched side of the
tufted backing with a binder. While any suitable technique can be
used, preferred contacting techniques for binder in any particular
form are those adapted to the form of the binder in a way that
facilitates or promotes contact between softened resin of the
binder and the stitched side of the backing. More preferably, the
contacting technique is one that facilitates or promotes such
contact such that softened resin contacts the stitched side in a
substantially uniform manner relative to the entire stitched
surface or at least a substantial portion of its area. Binder in
particulate form, e.g., powder, pellets, flake, granules, can be
contacted with stitched sides of backings by depositing the same
onto stitched surfaces or otherwise applying the binder from
suitable solids feeding equipment such as hoppers or other
dispensers suitably positioned in relation to the tufted backing.
Loose fiber can be sprinkled, spun or otherwise deposited onto
stitched surfaces, with combs or other spreading devices used as
may be desired or needed to aid in distribution of the fibers.
Liquids can be used to aid in applying binders in the form of
particulates or fiber, for example by forming pastes or slurries of
binder that are spread onto backings. In such cases, the liquid
should be one that is easily removed, such as by heating at
temperatures below that at which the tufted backing is damaged;
liquids used as the liquid component of the stitch bind composition
are preferred. Binders in the form of film, sheet, fabrics or other
fibrous assemblies can be fed into contact with the tufted backing
from rolls, moving belt conveying systems or other sources of
supply. As discussed above, binders in the form of coatings,
layers, fibers or fibrous assemblies can be included or
incorporated into backings to be tufted before tufting thereof,
into additional backings when the same are used, or into both. Such
composites of backings and binders can have the binder disposed on
one or both surfaces of the backing. Thermoplastic binders with
resin in softened or melted form can be extruded, coated, spun as
filaments or otherwise applied to stitched surfaces or other
backings.
[0089] Contacting a thermoplastic binder and the stitched side can
be conducted at any stage of the process prior to cooling the
softened resin of the thermoplastic binder to solidify the resin.
As discussed above, such contact can be affected during tufting if
the binder is included in a backing to be tufted or incorporated
into such a backing before tufting. Binder in other forms can be
contacted before, after or both before and after application of the
stitch bind composition and before, after or both before and after
heating to remove the liquid component thereof. When binder is
applied to the stitched side of the backing with the resin of the
binder in softened form, contacting the binder and the stitched
side takes place after heating to at least soften the resin of the
binder. When using binders that are applied to the stitched side
with the resin of the binder in solid form, contacting takes place
before heating the binder to soften the resin thereof. When
combinations of binders in different forms or of different
compositions are used, they can be contacted with the stitched side
of the tufted backing in the same or separate steps. Contacting the
binder with the stitched side is most preferably conducted so that
the presence of binder in contact with the stitched side will not
adversely affect application of stitch bind composition in contact
with the stitches. To this end, contacting the thermoplastic binder
and the stitched side of a tufted backing during tufting or after
application of stitch bind composition are especially preferred.
When used to secure tuft stitches and to bond additional backings
to the stitched side of the tufted backing, the thermoplastic
binder, tufted backing and additional backing are contacted in the
same or separate operations to form an intermediate structure in
which binder is disposed between the stitched side of the tufted
backing and the surface of the additional backing to be secured
thereto.
[0090] The thermoplastic binder is used in an amount effective to
secure the tuft stitches in the final carpet structure and, if also
used for bonding of additional backings, to secure the same to the
stitched side of the tufted backing. Specific amounts will vary
depending on factors such as form of the binder and manner in which
it is applied, composition and flow properties of the resin of the
binder, face yarn characteristics, carpet style and properties.
Preferably, the binder is used in amounts effective to provide at
least about 1 ounce of resin per square yard of area of the
stitched side of the tufted backing because lesser amounts may
provide insufficient resin for adequate bonding or be difficult to
apply in a manner conducive to good distribution of softened or
melted resin in contact with the stitched side of the backing. More
preferably, the amount of binder is such as to provide about 2 to
about 15 osy to promote good contact, distribution of softened
resin and bonding without use of amounts so large that they can
increase weight or reduce flexibility of final carpet structures
and thereby limit installation benefits otherwise attainable. Most
preferably, thermoplastic binder is used in an amount providing
about 3 to about 12 ounces of thermoplastic resin per square yard
of carpet to achieve desirable tuft bind and lamination of
additional backings while also ensuring other benefits of the
thermoplastic binder.
[0091] Another step of the carpet manufacturing processes in which
application of stitch bind composition and heating to remove the
liquid component thereof are employed comprises heating a
thermoplastic binder to soften a thermoplastic resin component
thereof without damaging the tufted backing. As noted above, the
term "soften" is used to mean heat softening or melting of the
resin. Although a subsequent step of such processes involves
cooling the binder with the resin thereof in softened form in
contact with the stitched side of the tufted backing to solidify
the resin, it will be understood from the preceding description
that heating to soften the resin of the binder can be conducted
with or without the binder and the stitched side in contact that
is, before or after contacting the binder and the stitched side.
Thus, heating to soften the resin of the thermoplastic binder can
be conducted by heating the binder in contact with the stitched
side of the backing, as where binder in the form of a powder, loose
fiber, fabric, film, coating on a backing or other solid is applied
or brought into contact with the stitched side of the tufted
backing or is part of or added to a backing to be tufted.
Alternatively, the binder can be softened before being brought into
contact with the stitched side of the tufted backing, as when
binder with softened resin is extruded, spun or coated onto the
stitched side of the tufted backing or into contact with the
stitched side and an additional backing.
[0092] Heating to soften the resin of the binder is conducted at a
temperature equal to or above the softening point of the resin and
without damaging the components of the tufted backing. Preferably,
heating is such that temperature of the tufted backing as a result
of the heating, or of its contact with softened resin of a
previously heated binder, does not exceed a temperature about
10.degree. C. less than that at which the tufted backing is
damaged, and more preferably about 20.degree. C. less, to provide a
safety margin against such damage. For manufacture of carpets in
which the backing and face yarn are composed of thermoplastic
resins, heating to soften the binder preferably is such that
temperature of the tufted backing does not exceed a temperature
about 15.degree. C. below the melting point of the lowest melting
resin of such face yarn and backing. For carpets made from commonly
used materials of construction, heating is preferably such that the
temperature of the tufted backing does not exceed about 150.degree.
C. Heating times generally range from several seconds to several
minutes, with more specific times varying with heating
temperatures, composition of the binder and tufted backing, manner
of contacting and equipment configuration, capabilities and
operation. For common carpet materials, when thermoplastic binders
in solid form and comprising preferred resins as described herein
are contacted with a tufted backing, or with a tufted backing and
an additional backing, and then heated to soften the resin of the
binder, heating times of about 0.3 to about 8 minutes are preferred
when heating is conducted using circulating air ovens or other
heating devices with similar heat transfer capabilities. Particular
times for specific combinations of materials, equipment
configurations and other variables can be easily determined by
routine experimentation guided by the description provided
herein.
[0093] Heating to soften the resin of the binder can be conducted
by any suitable technique. When such heating precedes contacting
the binder and the stitched side of the tufted backing, it is most
conveniently accomplished using an extruder. When such heating is
conducted with the binder and the stitched side in contact, heating
in a circulating air oven, by passage over heated rolls, or with
electric or infrared heaters are examples of suitable
techniques.
[0094] Another step of the processes in which application and
heating of the stitch bind composition according to this invention
are conducted comprises cooling the thermoplastic binder with the
resin thereof in softened form in contact with the stitched side of
the tufted backing to solidify the resin. Although considerable
variation is possible in the sequence of other steps of the
process, cooling to solidify softened resin of the binder is
completed last among the steps of providing a tufted backing,
contacting the backing and thermoplastic binder, heating the binder
to soften the resin thereof and cooling to solidify the resin.
[0095] The result of the cooling step is to convert the softened
resin of the binder to solid form in contact with a plurality of
the stitches or the stitches and the backing surface on the
stitched side of the tufted backing, thereby anchoring tufts to the
backing within the final carpet structure. When an additional
backing is to be laminated to the stitched side of the tufted
backing, the binder with softened resin disposed between the
stitched side of the tufted backing and a surface of the additional
backing is cooled and the solidified resin of the binder serves to
anchor the tufts and to secure the additional backing to the tufted
backing at the stitched side thereof.
[0096] Cooling occurs at a temperature below the softening
temperature of the thermoplastic resin of the binder; in this
particular context the term "softening temperature" refers to the
temperature at which the resin changes from a heat softened or
plastified state to a solid. Cooling times vary depending on
factors such as choice of resin of the thermoplastic binder,
temperature of the softened binder resin, method of cooling and
equipment configuration. In general, cooling takes place for at
least long enough that the resulting cooled structure can be
handled, for example by winding onto a roll, or subjected to
further processing without flow or irreversible deformation of the
resin. Cooling generally takes place over a period of several
seconds to several minutes. Conveniently, cooling is accomplished
by simply exposing the backing or backings in contact with softened
or melted binder to ambient conditions, for example by passing the
same out of or away from a heat source. Other cooling techniques,
such as circulating cool air or passage of the structure into a
zone, or over rolls, maintained at a desired cooling temperature
are also suitable.
[0097] In manufacture of carpets from backings that can undergo
shrinkage as a result of heat exposures encountered during contact
with the softened resin of the thermoplastic binder, it is
preferred to apply tension to the intermediate carpet structure
during all or part of the heating and cooling steps. Tension is
preferably applied in the cross direction--that is, perpendicular
to the direction of advancement of the structure through the
process line, also referred to as the machine direction--or in both
the machine and cross directions. Forces conventionally applied to
prevent shrinkage during heating and cooling of carpets or backings
for other purposes are suitable in the invented process and are
known to persons skilled in the art. Tension in the cross direction
is conveniently applied using a tenter frame or other suitable
widthwise stretching device. Machine direction tension can be
applied by adjusting equipment drives for advancement of the
intermediate carpet to and from cooling so that the latter is
slightly faster.
[0098] While not required, when the softened resin of the
thermoplastic binder is in contact with the stitched side of the
tufted backing, or with that surface and a surface of an additional
backing, application of force to the so-contacted materials can be
beneficial to improve distribution of the resin within the
structure and, on cooling to solidify the resin, encapsulation of
tufts and bonding to the backing or backings. When such contact
occurs with the pile surface of the tufted backing disposed
downward, gravity alone can be an effective force. Other convenient
means for application of force include passing the tufted backing,
or the tufted and additional backings, in contact with the softened
resin of the binder between rolls or over a roll under tension.
Preferably, force of about 5 to about 100 pounds per linear inch is
applied to promote this distribution while guarding against damage
to face yarn tufts.
[0099] As described previously and evident from the foregoing
description of processes using thermoplastic binders, the invented
process is capable of considerable variation in many respects. It
can be conducted continuously or discontinuously, with the former
being generally preferred for its greater efficiency. The tufted
backing can be prepared in a discrete operation conducted
separately from the process or tufting can be integrated with the
process. Stitch bind composition can be applied to a tufted backing
and the result heated to remove the liquid component in one
operation or location and the resulting tufted backing with
filaments of a plurality of its stitches bonded by the organic
polymer or residue thereof taken up on rolls and subsequently used
with thermoplastic binders in completely discrete operations or
locations. Alternatively, the tufted backing can be prepared and
fed in-line to downstream processing. Stitch bind composition can
be applied to the stitched side of the backing at any point in the
process after tufting a backing but before the softened resin of
the thermoplastic binder is solidified in contact with the stitched
side. Also as described above, the thermoplastic binder can be
applied in solid form or with the resin of the binder softened.
Backing-thermoplastic binder composites can be prepared, or binders
otherwise applied to or incorporated into backings before tufting
thereof, such as by coating a backing or affixing binder fibers or
fabric thereto in advance of tufting. The binder can also be
applied to the tufted backing after tufting. One or more additional
backing structures can be used in the process, with the same being
laminated to the tufted backing, included as part of the tufted
backing, or both. Binder can be applied to or incorporated-into
backings that are not tufted but are laminated to the tufted
backing or otherwise incorporated into the carpet structure.
Heating to remove the liquid component and heating to soften the
resin of the thermoplastic binder can be conducted in the same or
different steps. Preferably, application of the stitch bind
composition and heating to remove the liquid component thereof are
conducted before cooling of the softened resin of the thermoplastic
binder so that vaporized liquid component does not interfere with
cooling of the resin or become entrapped or create voids in the
solidified resin. When using thermoplastic binders that are applied
to the tufted backing in solid form with subsequent softening of
the resin of the binder in contact with the stitched side of the
backing, it is most preferred to apply the stitch bind composition
to the stitched side and remove the liquid component before
softening the resin of the thermoplastic binder. When using
thermoplastic binders that are contacted with the stitched side
with the resin of the binder in softened form, it is most preferred
to apply the stitch bind composition to the stitched side and heat
the structure to remove the liquid component before application of
the thermoplastic binder. Intermediate or finishing steps can also
be included in the processes; examples include dying and washing of
intermediate or finished carpets, cutting of looped tufts and
application of topical treatments for stain, mold, mildew
resistance or other improved properties and taking up carpets in
finished form. Persons skilled in the art will appreciate that
other variations and modifications of the process can be made
without departing from the scope of the invention.
[0100] It also will be appreciated that a wide range of materials
is suitable for use in the invented process. The stitch bind
composition and components thereof are described above. Other
materials include backings, face yarn and thermoplastic binder.
[0101] Any suitable backing can be used for or included in the
tufted backing. A wide range of backings for carpets is well known.
They are generally flat or sheet-like, tuftable materials with
flexibility and integrity suited for process manipulations and
sufficient strength and tuftability to allow penetration by needles
and face yarn during tufting while retaining strength and integrity
for carpet performance. Backings can be constructed in any suitable
manner and from any suitable materials for attaining desired
performance characteristics. Examples include woven, knitted and
nonwoven fabrics, films, sheets and composite structures having one
of more of the above combined with one or more others or with other
materials such as scrims and netlike nonwoven fabrics. Preferred
materials of construction for the backing comprise thermoplastic
resins due to their desirable combination of cost and properties.
Examples include polyolefins, such as polypropylene, polyethylene
(low, linear low, medium or high density or so-called metallocene
polyethylenes), copolymers of ethylene or propylene with each other
and/or other monomers, nylons, polyesters and blends comprising
such resins. Backings constructed from paper, natural materials
such as jute and hemp, and other non-thermoplastic materials also
can be used although they do not afford the potential melt
reprocessing benefits of thermoplastic backings.
[0102] Woven polypropylene fabrics, and particularly those woven
from tapes, also referred to as slit film or ribbon yarns, are most
commonly used for such backings owing to their superior combination
of cost, tuftability, and properties such as strength, durability,
mold and mildew resistance. An example is Polybac.RTM. Fabric which
is a woven polypropylene primary backing made and sold in a wide
range of styles by Amoco Fabrics and Fibers Company.
[0103] Preferred woven backings for the tufted backing are flat
fabrics woven from tapes in a plain weave with an average of about
10 to about 32 yarns per inch in each of the warp and weft
directions. Tape dimensions generally vary from about 30 to about
125 mils wide and about 1 to about 3 mils thick; tape deniers
generally range from about 300 to about 1500. Particularly
preferred primary backings are plain weave fabrics woven from
polypropylene tapes with about 18 to about 28 warp tapes per inch
and about 8 to about 18 weft tapes per inch wherein the warp tapes
are about 1.3 to about 2 mils thick and about 30 to about 60 mils
wide and the weft tapes are about 1.7 to about 2.3 mils thick and
about 80 to about 120 mils wide. Tapes can be contoured or
uncontoured. Contoured tapes can provide particular advantages when
woven into a backing and coated with a lower melting thermoplastic
resin to stabilize the weave and facilitate tufting by preventing
shifting of tapes due to impingement of tufting needles. Coated
backings woven from contoured tapes are disclosed in commonly
assigned U.S. Pat. No. 5,925,434. The lower melting point of the
coating resin also makes such coatings suitable as thermoplastic
binders or as components thereof. Fibrillated tapes can also be
included in backings to be tufted.
[0104] Preferred nonwoven backings are generally relatively dense
mats or webs of continuous filaments or staple fibers. The
filaments or fibers commonly comprise polyester or polyolefin
resins, such as polyethylene terephthalate and polypropylene,
respectively. Polyester is generally preferred for nonwoven
backings due to its greater heat stability and greater resistance
to shrinkage. An example of a known polyester nonwoven backing is
Lutradur.RTM. fabric. Nonwoven backings can also be composed of
higher and lower softening point fibers or filaments, such that
thermoplastic binder is thereby incorporated into the backings.
Nonwoven backings also can be calendered or needled to improve
their integrity, dimensional stability or other properties.
Nonwoven backings generally have basis weights in the range of 3 to
about 6 osy with filament deniers generally ranging from about 3 to
about 20. Although nonwoven backings are generally less
dimensionally stable than woven backings, and therefore less
commonly used in many conventional carpet applications, use of the
stitch bind composition and thermoplastic binder with tufted
nonwoven backings according to this invention can provide
improvements that expand potential utility of the backings.
[0105] As additional backings useful according to the invention,
whether used in preparation of the tufted backing, laminated to the
stitched side of the tufted backing or in other ways, any suitable
backing can also be used. Generally, any of the backings described
above can be used as an additional backing, including the
aforementioned films, woven, knitted and nonwoven goods and
composite materials. In addition, scrims, netlike nonwovens and the
like can be used or laminated to such other structures to provide
high levels of dimensional stability and/or improved tuftlock.
Preferred additional backings are materials constructed of
thermoplastic resins, and particularly polypropylene tapes and/or
yarns. While woven, nonwoven and knitted fabrics are most commonly
used, particularly preferred additional backings are conventional
polypropylene secondary backing fabrics which are typically woven
from polypropylene tapes, or from such tapes in one direction and
polypropylene filament or spun yarns in a perpendicular direction.
Plain weave and leno constructions are preferred. Secondary
backings used in carpets with conventional latex binders are often
constructed in an open weave to promote uptake of binder by the
backings. While such open weave backings are useful in the invented
process, flow properties of the thermoplastic binders used
according to the invented process are such that close weave
constructions are also well suited.
[0106] For use in the invented process, especially preferred
additional backings are fabrics woven from polypropylene tapes, and
especially those with such tapes in the warp and polypropylene spun
or multifilament weft yarns, in a plain or leno weave construction
with about 10 to about 24 warp tapes per inch and about 4 to about
14 weft tapes or yarns per inch. Specific examples of such
secondary backings are ActionBac.RTM. Fabrics available from
Amoco.
[0107] As discussed above and described below in connection with
the thermoplastic binders used according to the processes to which
the invention relates, it also is contemplated to include or
incorporate one or more thermoplastic binders in a backing,
including the backing or backings to be tufted, additional
backings, or both. Composite backings having a binder attached or
affixed to a backing are suitable as are backings in which the
binder is directly included or incorporated into the backing, such
as in the case of backings constructed from tapes or yarns
comprising higher and lower softening point resins.
[0108] Face yarns suitable as components of the tufted backings
used according to the invented process also are well known and can
be composed of any suitable material. The yarns comprise a
plurality of filaments. Preferably, filaments comprise at least one
thermoplastic resin; examples include nylon, polyester,
polypropylene or acrylic resins. Continuous filament yarns and spun
yarns are suitable. Natural fiber yarns, such as those in which the
filaments are wool or cotton also are contemplated although they do
not afford the melt reprocessing benefits of yarns with
thermoplastic filaments. Continuous filament yarns used for carpet
face yarn are usually bulked to provide texture resembling natural
fiber yarns. Bulking is introduced by various techniques such as
crimping, texturing with fluid jets, twisting and detwisting and
the like. Twisting, cabling, plying, heatsetting and combinations
of such techniques are often used to impart or preserve bulk in
such yarns. Such bulked continuous filament yarns are commonly
referred to as "BCF" yarns. Nylon BCF yarns, composed of either
nylon 66 or nylon 6, are most commonly used in carpets although
polypropylene BCF yarns are also widely used, as are nylon spun
yarns and polyester yarns. All are well suited for use in the
present invention. Pigmented, or so-called solution-dyed yarns,
prepared by incorporating pigments into the resin from which
filaments are melt spun, are suitable as are natural color yarns
that are dyed after tufting, for example as part of a finishing
step during carpet manufacture. Generally, BCF face yarns have
linear densities of at least about 1200. Deniers up to about 10,000
are common in most conventional carpet styles although in some
styles, such as Berbers, yarn deniers as high as 20,000 and even
greater are known. Filament counts of typical face yarns range from
about 70 to about 1200, with about 8 to about 30 denier per
filament.
[0109] Thermoplastic binders used for bonding of backings and
anchoring tufts to or between backings are also well known and can
be provided in a wide range of forms and from a wide range of
materials, as described above. The binder comprises a thermoplastic
resin that is capable of being softened in contact with the tufted
backing and additional backings that may be used, or of being
softened and then contacted with the tufted backing and additional
backings if used, without damaging the tufted backing or the
additional backing. Thus, the resin is one that can exist in a
softened state in contact with the tufted backing, or with the
tufted backing and additional backing or backings, at a temperature
that does not damage such other components. For thermoplastic
binders that are contacted with tufted backings or tufted backings
and additional backings before heating to soften the resin of the
binder, softening temperature of the resin of the binder is below
the temperature at which the backings are damaged by heat. For
binders contacted with backings with the resin of the binder
already in a softened state, resin softening points can exceed
temperatures at which the backings are damaged provided that
contacting of the binder and the backing or backings does not
damage the backing or backings, for example as a result of cooling
that inherently occurs as an extruded film or filament of resin
passes from a die to a substrate and/or when it contacts a lower
temperature substrate or a roll at a lower temperature. Preferred
binder resins are those that can be heat-softened or melted, or can
be contacted in a heat softened or melted state with a tufted
backing and additional backings if used, at a temperature at least
about 10.degree. C. below the lowest temperature at which backings
and face yarns are damaged by heat, and more preferably at least
about 20.degree. C. below such temperature.
[0110] Preferred binder resins also exhibit sufficient flow or
formability when softened or melted so that they flow around or
encapsulate the tuft stitches and/or the junctions of the stitches
with the backing. The resins also should have sufficient cohesive
strength that, on cooling, solid resin encapsulates or coats the
tufts and adheres tufts to additional backings with sufficient
strength and integrity to anchor the tufts and provide a good bond
between the stitched side of the tufted backing and any additional
backing laminated thereto. For use with backings and face yarns
composed of thermoplastic resins, particularly preferred resins of
the thermoplastic binder are those in which the onset of softening
occurs at temperatures about 10.degree. C. or more below the lowest
softening-onset temperature of the thermoplastic resins of the
other components, and more preferably at about 15 to about
30.degree. C. below such temperature because these temperatures are
high enough to allow a wide range of candidate resins for the
binders when using backings and face yarns that are commonly used
in carpets, but also low enough that heating to soften the resin
can easily be accomplished without damage to backings and face
yarns. In general, when using polypropylene backings and face yarns
composed of nylon, polypropylene, polyester or natural fibers,
preferred resins for the thermoplastic binder soften at
temperatures of about 100 to about 150.degree. C.
[0111] As described above, the thermoplastic binder preferably is
used in a form that facilitates contact of the stitched side of the
tufted backing with softened resin of the binder so that the
softened resin is or can be distributed in substantially uniform
weights per unit area in contact with the stitched side. It will be
understood that the distribution of resin in contact with the
stitched side can be continuous or discontinuous. As described
above, the binder can be used in a variety of solid forms,
including by way of example, pellets, powder, flake, or other
particulates, loose fibers or fibrous assemblies such as webs,
scrims or grids and woven or nonwoven fabrics, films, sheets and
coatings. The binder can also be present in or incorporated into
backings as in backing-binder composites or otherwise, for example
by bonding a fibrous web, nonwoven fabric or loose fibers to a
surface of a backing by needling, thermal bonding, with adhesives
or by other suitable means. The binder can also be in the form of a
coating, film or layer disposed on at least one surface of a
backing. In any of these cases, the backing or composite into which
the binder is incorporated or in which it is present or to which it
is adhered can be a backing from which the tufted backing is formed
or it can be an additional backing that is laminated or otherwise
affixed to the tufted backing. The binder can also be provided in
the form of a melt or softened resin as when resin is extruded or
otherwise applied in a heat softened state to a backing surface. As
noted above, binders in the form of film, sheet, fabric or coating,
and those applied as a softened or melted layer or film, are
advantageous because they are in a form that is well matched to
process operations and facilitate substantially uniform application
of binders to backings. Binders of the same or different form and
composition can be used in combination. As an example, use of a
primary backing with needled binder fibers or fabric as a backing
to be tufted and a secondary backing with a layer or coating of
binder bonded thereto can be used with good results. Use of
combinations of binders in different forms and/or with different
thermoplastic resins is also contemplated and can allow tailoring
components of binders to elements of carpet structure, style or
components, for example to match resin melt viscosities to backing
constructions or resin compositions or polarities to backing or
face yarn compositions.
[0112] In the case of binders in the form of fibers, continuous or
discontinuous fibers are suitable, with the latter generally being
better suited to process use and more uniform application to
stitched sides of backings. For discontinuous fibers, fibers of any
suitable length and diameter can be used. Lengths up to about 8
inches are preferred because longer fibers can be difficult to
apply. Combinations of fibers with different dimensions can be used
to promote more even distribution of binder resin on softening
thereof and, in turn, more uniform and consistent bonding on
cooling of the resin. Loose fibers can be supplied to the stitched
side of a tufted backing from a hopper or other suitable dispenser.
Fibers also can be needled to backings to be tufted or to
additional backings to be laminated to the stitched side of a
tufted backing. Also as described above, when one or more backings
used according to the process is a nonwoven backing, thermoplastic
binder in the form of fibers can be incorporated directly into the
backings by using the fibers in combination with other fibers from
which the backings are made. The resulting backings thus comprise a
combination of higher softening and lower softening fibers.
[0113] Binders in the form of powder, flakes or particulates
comprising thermoplastic resin can be of any suitable dimensions
and configuration for use in the process. As with loose fiber,
binder in the form of powder, flake or particulates can be applied
from a hopper or other suitable solid feeding device. Binders in
such form can also be slurried in liquids or formed into a paste to
facilitate application. Also as with loose fibers, application of
combinations of different particle sizes can contribute to more
uniform distribution of binder in contact with stitched or other
backing surfaces and bonding on cooling of the binder to bond
carpet components.
[0114] Nonwoven fabrics, or webs, suitable for use as thermoplastic
binders according to the invention include both continuous filament
nonwovens, such as spunbonded and centrifugally spun fabrics, and
fabrics comprising discontinuous or staple fibers, such as carded
staple fiber webs, needlepunched nonwovens, hydroentangled webs and
the like. Melt blown webs of continuous or discontinuous fibers can
also be used, as can other fibrous assemblies such as woven fibers,
scrims and needlepunched fibers. Filaments or fibers of these
materials can be of any suitable dimensions, with deniers of about
0.1 to about 20 being particularly well suited. Fabrics and webs
can be used in weights corresponding to desired application rates
and can be conveniently provided to the process from rolls,
provided in-line from manufacture thereof or by other suitable
means. Preferred fibrous assemblies are nonwoven, continuous
filament webs and staple fiber webs, and particularly those having
basis weights of about 1 to about 12 osy. Such webs having
sufficient strength and integrity that they can be easily and
conveniently handled for use in the process and having sufficient
uniformity of coverage as to aid in achieving good distribution of
softened resin on heating are more preferred, both for use in the
process as freestanding webs and in composites with backings.
Centrifugally spun continuous filament webs, spunbonded webs and
needlepunched staple fiber nonwoven fabrics or webs with such
properties are especially preferred.
[0115] In the case of binders provided in combination with, or as
part of, one or more backings used in the process, the composites
and combinations can also be provided in a wide range of forms. As
noted above, binder in the form of a layer can be coated or
laminated to one or more backing surfaces, binder in the form of
fibers or fibrous assemblies can be affixed to one or more backings
or binder in the form of fibers can be included in nonwoven
backings. In greater detail, binders in the form of a layer applied
to a backing can be disposed continuously or discontinuously over
the backing and to one or both surfaces thereof. Continuous layers
are preferred for better distribution of softened resin. Layer
thickness will depend on nature of the backing and composition of
the resin of the binder and can be selected with reference to the
weight of resin to be used. Preferably, layer thicknesses do not
exceed about 1/4 inch because thicker layers may make tufting or
other handling of backings more difficult. Backings having binder
in the form of fibers or fabrics affixed thereto can be prepared by
any suitable means. Needling of binder in such form to backings can
be advantageous because needling typically results in presence of
fibers on both surfaces of backings. When presence of the fibrous
binder on only one surface of a backing is desired, thermal or
adhesive bonding of the fibers to the backing surface is preferred.
Binder fibers can also be included in the fibers or yarns from
which backings are made and bicomponent fibers and yarns containing
higher and lower softening point resins can be used to form
backings.
[0116] Binders supplied in the form of softened resin are typically
extruded directly onto stitched backing surfaces or between the
same and another backing as the same are brought together. Resin
can be extruded from a suitably configured and dimensioned die.
Other suitable means for applying binder with the resin thereof in
melted form include spinning and melt blowing fibers of softened
resin directly onto backing surfaces.
[0117] Suitable resins of the thermoplastic binder are
thermoplastic resins that soften in relation to temperatures at
which other carpet components are damaged as described above. In
addition, the resins soften above about 50.degree. C. because lower
softening point resins may not withstand temperatures encountered
in storage and use of finished carpets. Preferred resins have flow
properties that are conducive to flow or formability of softened or
melted resin in contact with backings and encapsulation of
stitches. Particularly preferred resins for use with common carpet
materials, such as polypropylene backings and nylon, polyester and
polypropylene face yarns, soften at temperatures up to about
190.degree. C., provided that in the case of thermoplastic binders
that are contacted with a tufted backing before heating to soften
the resin of the binder, softening points are up to about
150.degree. C. Such resins preferably have flow properties at such
temperatures corresponding to MIs of about 1 to about 200 g/10
min., more preferably from about 2 to about 150 g/10 min., and most
preferably from about 5 to about 100 g/10 min.
[0118] As previously described, preferred compositions of the
resins are polyethylenes, ethylene-propylene copolymers and blends
containing the same due to their beneficial combination of
softening points well suited to use with common backing and face
yarn materials, good flow properties or deformability when melted
or softened, and suitable cohesive strength for good bonding of
stitches and lamination of secondary backings if used. For carpets
with nylon face yarns, thermoplastic binders comprising resins with
polar functionality or resins modified by addition of such
functional groups, and especially hydroxyl, carboxyl or amide
functionality, can provide enhanced bonding to face yarns as a
result of interaction between the functional groups of the binder
resin and the amide linkages of the nylon. Examples of resins
having polar functionality include ethylene-acrylic acid
copolymers, maleated polypropylenes and maleated styrene-butadiene
and styrene-ethylene-butylene copolymers.
[0119] The thermoplastic binder can consist entirely or essentially
of one or more thermoplastic resins or it can contain one or more
resins in combination with additives and modifiers if desired;
examples include pigments and colorants, flow aids, flame
retardants, antimicrobials, stabilizers and process aids, fillers
and extenders. Binders consisting entirely or essentially of
thermoplastic resin are preferred for maximizing resin content of
the binders.
[0120] Another embodiment of the invention provides carpets,
including carpets made by the invented process and carpets with
features of construction that can provide improved performance in
use.
[0121] Carpets prepared according to the invented process are
advantageous over conventional carpets in a number of respects.
When thermoplastic backings and face yarns are employed, trim and
waste generated in their manufacture can be used in melt
reprocessing operations. As a result, manufacture of carpets
according to the invention can be performed with improved
efficiency in materials usage. Manufacture of carpets according to
the invented process also eliminates need for preparation and
handling of latex formulations. Further, for a given carpet style
in terms of tufting pattern and gauge, pile height and face yarn
type, carpets made according to the invented process can be made in
lighter weights than conventional carpets and are more flexible and
more easily manipulated in process operations as well as subsequent
handling and installation. Other advantages of carpets according to
the invention are described above.
[0122] While carpets made according to the invented process
represent an aspect of the invention, the invention also provides
carpets that are considered novel and improved over known carpets
by their structure, or their structure and properties, but without
regard to the particular manner in which they are made. While the
invented process represents a preferred method for making such
improved carpets, carpets with the improved features according to
this aspect of the invention are considered a part of the invention
without regard to any particular method of manufacture.
[0123] Carpets according to this aspect of the invention comprise a
backing, face yarn, organic polymer component and a thermoplastic
binder that is substantially free of crosslinked polymer solids and
inorganic particulates. These components are associated such that
the face yarn penetrates the backing such that a plurality of tufts
of the face yarn project from a surface of the backing and a
plurality of face yarn stitches are disposed on an opposite surface
of the backing, filaments of a plurality of stitches are bonded by
the organic polymer component, and a plurality of stitches are
bonded to the backing with the thermoplastic binder. In another
embodiment, carpets according to the invention further comprise a
secondary backing that is bonded to the stitched side of the
backing described above with the thermoplastic binder. The carpets
preferably contain less than 3 osy crosslinked polymer solids, and
more preferably less than about 2 osy of such crosslinked solids,
exclusive of species such as the gel particles and crosslinked
particles or domains that may result from melt processing aids
noted above.
[0124] In greater detail, penetration of the backing by face yarns
in the invented carpets is as described above with respect to the
tufted backings used in or provided to the invented process. Tufts
are further secured within the carpets by the thermoplastic binder
which is distributed continuously or discontinuously in contact
with the stitches of the backing and encapsulates all or part of
the stitches, and may also contact the backing, to anchor or lock
the tufts within the carpet structure. Preferably, the binder is
present in the finished carpet so that it is distributed within the
carpet at substantially uniform amounts per unit area of the
carpets. The thermoplastic binder is present in an amount effective
to bond tuft stitches within the carpet and to bond to the stitched
side of the tufted backing any additional backing that may be
laminated thereto with the binder. Preferably, carpets contain
about 2-15 osy of thermoplastic binder because lesser amounts may
provide insufficient bonding and greater amounts can increase
stiffness and weight. More preferably, about 3 to about 10 osy
thermoplastic binder is present.
[0125] The carpets also comprise an organic polymer component
bonded to filaments of the stitches. The organic polymer component
of the carpet normally is present in discontinuous form and
preferably in the form of small, discrete domains bonded at least
to filaments of the stitches and usually also to the backing
surface, the thermoplastic binder or both. The organic polymer
component of the invented carpets comprises an organic polymer or
residue of the type described above in connection with the invented
process. Accordingly, the organic polymer component of the carpets
can comprise an organic polymer that is the same as organic
polymers of the type described above in connection with the stitch
bind compositions used in the invented process or it can comprise a
reaction product of such a polymer or of such a polymer with other
components. The organic polymer component bonds filaments of the
stitches so that filaments of the face yarn tufts are more securely
held in the carpet structure. Preferred carpets according to the
invention contain about 0.2 to about 3 osy of organic polymer
component, a substantial portion of which is adhered to filaments
of the stitches. More preferably, the organic polymer content of
carpets is about 0.3 to about 2 osy.
[0126] The invented carpets are composed of other materials as
described above in reference to the invented process. Preferred
backings are woven polypropylene fabrics. Preferred face yarns
comprise nylon, polypropylene and polyester filaments. Preferred
thermoplastic binders comprise the polyethylenes, copolymers and
blends as described above.
[0127] The carpets can be provided in styles, weights, tuft
densities and pile heights as desired. Tufted carpets can be
provided in a broad range of styles and weights. Examples of the
former include Saxony, Berber, velvet, cut-and-loop, cut pile,
high-low, and loop pile carpets. Cut pile styles are frequently
used for residential carpet applications while loop pile styles are
typically used for commercial, hospitality and carpet tile
applications. Weights typically range from about 10 to about 80
osy, with about 14 to about 45 osy being preferred for commercial
carpets and about 12 to about 65 osy for residential carpets. Pile
heights of about 3/8 to about 7/8 inch are common in residential
carpets while about 3/16 to about 1/2 inch are common of commercial
carpets. Tuft densities typically range from about 20 to about 300
needle penetrations per square inch for both types of carpets.
While these constructions are typical of the types of carpets
currently used in various applications, it will be appreciated by
those skilled in the art that heavier and lighter weights, longer
or shorter pile heights and greater or lesser tuft densities also
can be suitable for various end uses and are contemplated for the
invented carpets. Other things being equal, the invented carpets
are lighter in weight than carpets made using conventional aqueous
latexes because the relatively high filler loadings found in the
latter are not used in the invented carpets.
[0128] Carpets according to this aspect of the invention preferably
have improved fuzz resistance, and often have improved tuft bind
strength as compared to comparable carpets lacking the organic
polymer component. More preferably, the carpets have Fuzz Ratings
determined according to the examples appearing below, and reported
on the 11 point scale used therein, of 4 or lower, and more
preferably of 2 or lower. Tuft bind strengths of the carpets
preferably are at least about 2 pounds in cut pile carpets and at
least about 5 pounds in loop pile carpets. More preferably, cut
pile carpets have tuft bind strengths of at least 3 pounds and loop
pile carpets have tuft bind strengths of at least about 6.25
pounds. The invented carpets also are resistant to water uptake and
consequently retain their fuzz resistance and tuft bind strength
even when used in environments in which contact with water
occurs.
[0129] The following examples illustrate the invention. They are
not to be considered limiting.
[0130] In the examples, Fuzz Ratings of loop pile carpets were
determined using a test generally referred to as the Velcro Roller
test. The test is commonly, though not universally, recognized in
the carpet industry. It is not considered useful for testing cut
pile carpets because the test device used does not cause adequate
fuzzing of cut pile tufts for meaningful evaluation. The test uses
a two pound, three inch wide, two inch diameter cylindrical steel
roller equipped with a handle and covered with the hook portion of
Velcro.RTM. brand tape. The roller is manually rolled back and
forth over a section of carpet about six inches long for a total of
twenty passes, ten in each direction. Fuzz Rating is determined by
visual observation of filaments on the Velcro covered roll. Ratings
sometimes use a 5 point scale and sometimes an 11 point scale. In
the following examples, and otherwise for purposes of the
invention, the 11 point scale is used. Fuzz levels corresponding to
ratings on the two scales are generally as follows: TABLE-US-00001
Rating (5 Point Rating (11 Point Filaments on Roll Scale) Scale)
None 1 0 Extremely low 1 1-2 Very low - slight 2 3-4 fuzzing Low -
moderate 3 5-6 fuzzing Medium - 4 7-8 considerable fuzzing High -
severe 5 9-10 fuzzing
[0131] Carpets displaying no, extremely low, or very low fuzzing
are generally considered acceptable. U.S. Pat. No. 3,684,600
presents a similar ranking scale.
[0132] Tuft Bind strengths reported in the examples were determined
according to ASTM D1335.
EXAMPLE 1
[0133] A tufted carpet is prepared on a carpet line as illustrated
in the drawing operated at a line speed of 50 feet per minute (15
m/min). The tufted backing has a 152 inch wide primary backing
woven from polypropylene tapes in a plain weave construction with
24 warp tapes per inch by 15 weft tapes per inch. The primary
backing is tufted in a straight stitch pattern with 4000 denier,
cabled, heatset nylon BCF face yarn to form a cut pile with 8
stitches per inch on the stitched side, 1/8 gauge and face yarn
weight of 42 osy.
[0134] The stitch bind composition is a 15 wt % solids content, 3.3
cps, aqueous dispersion of solid ethylene acrylic acid copolymer
prepared by diluting a commercially available ethylene acrylic acid
copolymer dispersion in ammonia water, designated MichemPrime
4983-30R. The dispersion, before dilution, has nominal polymer
solids content of 30 wt %, viscosity of 1000 cps and its
ethylene-acrylic acid copolymer has nominal acrylic acid unit
content of 20 wt % and melt index of 300 g/10 min. The dispersion
is sprayed onto the stitched side of the tufted backing at 3.3 osy,
corresponding to 0.5 osy dry weight of the ethylene acrylic acid
copolymer, using a spray applicator system having 20 spray heads
positioned at intervals of about eight inches across the width of
the line and about 12 inches above the tufted backing. Spray is
delivered under pressure of about 30 psig in the form of a curtain
of droplets in a fan pattern about 12 inches wide at the surface of
the stitched side and with about half of the width of the spray
from each nozzle overlapped by spray from each of its adjacent
nozzles.
[0135] After application of the dispersion, the tufted backing with
the dispersion applied thereto is passed into a forced air oven
with air temperature maintained at 280.degree. F. (138.degree. C.).
At the line speed utilized, dwell time in the oven is one
minute.
[0136] A composite of a secondary backing and thermoplastic binder
is unwound from a roll and supplied into contact with the tufted
backing. The backing-binder composite has a 6.5 mil thick, 4.5 osy
layer of binder coated on a surface of a woven secondary backing.
The coating is composed of a linear low density polyethylene, with
nominal MI of 27 g/10 min, density of 0.941 g/cc and melting point
of 125.degree. C., identified as Aspun 6811A from Dow. The coating
was applied by extrusion coating a 6.5 mil thick layer of the
polyethylene resin onto a secondary backing fabric, identified as
ActionBac Style 3865 from Amoco, woven from polypropylene warp
tapes and polypropylene spun yarns in the weft in a 16.times.5 leno
weave construction. The coated secondary backing is contacted with
the stitched side of the tufted primary backing so that the coating
contacts the stitched side of the tufted backing. The resulting
intermediate structure advances into a forced air oven set at
300.degree. F. (149.degree. C.). At the line speed used, dwell time
in the oven is 21/2 minutes, which is sufficient to melt the resin
of the coating on the secondary backing fabric.
[0137] The intermediate structure with melted resin of the binder
passes from the oven into the nip between two steel rolls at
ambient temperature. The rolls are located within about three feet
from the oven so that the resin is still melted when the structure
reaches the nip. A force of 30 pounds per linear inch is applied at
the nip. The carpet is then taken up on a roll, with the takeup
located about 40 feet from the nip. The resin of the binder cools
to solid form during advancement of the structure away from the nip
roll pair to the takeup.
[0138] The resulting cut pile carpet has a construction and
properties, including tuft bind strength and fuzz resistance,
suitable for use in many typical residential carpet
applications.
EXAMPLE 2
[0139] A tufted carpet is prepared on a carpet line as illustrated
in the drawing operated at a line speed of 30 feet per minute (9
m/min).
[0140] The tufted backing has a primary backing fabric as in
Example 1 to which had been needled a thermoplastic binder in the
form of a 3 osy continuous filament nonwoven fabric prepared
according to U.S. Pat. No. 5,173,356. The filaments of the nonwoven
fabric were composed of a linear low density polyethylene resin
having nominal MI of 105 g/10 min, density of 0.930 g/cc and
melting point of 125.degree. C. The nonwoven fabric is needled to
the primary backing with 400 needle punches per square inch such
that a web is disposed on one side of the backing and a plurality
of filaments from the web penetrate to the other side of the
backing.
[0141] The primary backing with affixed binder is tufted in a
stepover stitch pattern with 5000 denier nylon BCF face yarn to
form a 1/4 inch high, loop pile with 8 stitches per inch and 1/8
gauge. Pile weight is 28 osy. The backing-binder composite is
tufted so that the pile extends from the side of the composite
having a plurality of filaments from the web and the stitches are
disposed on the web side of the composite.
[0142] Stitch bind composition as used in Example 1 is sprayed onto
the stitched side of the resulting tufted backing using the spray
system as in Example 1 at an application rate of 6.7 osy,
corresponding to 1.0 osy dry weight of polymer.
[0143] After application of the dispersion, the tufted backing with
the dispersion applied thereto is passed into an oven as in Example
1 set at 260.degree. F. (127.degree. C.). At the line speed
utilized, dwell time in the oven is 2 minutes.
[0144] A secondary backing-thermoplastic binder composite as in
Example 1 is unwound from a roll and advanced into contact with the
stitched side of the tufted backing so that the coating contacts
the stitched side.
[0145] The resulting intermediate structure is advanced into an
oven as in Example 1 set at 300.degree. F. (149.degree. C.). At the
line speed used, dwell time in the oven is 3.1 minutes, which is
sufficient to melt the resin of the filaments of the web needled to
the primary backing fabric and the coating on the secondary backing
fabric.
[0146] The intermediate structure with melted resin of the binders
passes from the oven to the nip roll pair configured as in Example
1 and through the nip where it is subjected to force of 30 pounds
per linear inch. The result is then cooled and the finished carpet
is wound onto a roll.
[0147] The resulting loop pile carpet has excellent tuft bind and
fuzz resistance properties and is constructed in a style
representative of typical commercial carpets such as are used in
office buildings, airports, retail stores and showrooms.
EXAMPLES 3-37
[0148] In the following examples, carpet samples were prepared from
various materials and Fuzz Ratings of loop pile samples and Tuft
Bind strengths of all samples were determined. Carpet samples were
made according to the following general procedure.
[0149] Tufted primary backings with various face yarns and primary
backing fabrics, as described in detail in connection with the
specific examples in which they were used, were prepared on a
laboratory scale tufting machine or obtained from commercial
sources. Additional backings, or composites thereof with
thermoplastic binders, were also used, again as described in
connection with specific examples in which they were used.
[0150] Samples of tufted primary backings and of additional
backings or additional backing-thermoplastic binder composites were
cut into rectangles 18 inches long and 12 inches wide, with the
longer dimension in the machine direction. Stitch bind compositions
in the form of aqueous dispersions or emulsions were prepared by
diluting various commercially available materials with water to
10-15 wt % solids or polymer contents. The materials from which the
stitch bind compositions were prepared and their solids or polymer
contents and viscosities as used are described in detail in Table
I. The dispersions were sprayed in a fine mist onto the stitched
sides of tufted backing samples using a household garden sprayer.
Spray was applied to substantially all of the stitches of the
stitched sides until estimated polymer contents reached desired
levels. Immediately after spraying, the wet, tufted backings were
placed stitched side up in a Hix 021 Infra-Air Conveyer Dryer that
had been preheated to 220.degree. F. (104.degree. C.). The samples
were removed from the oven after 10 to 12 minutes. Samples removed
from the oven were dry and filaments of the stitches were bonded
with polymer from the stitch bind composition or a residue
thereof.
[0151] Following drying, the tufted backings with bonded filaments
and an additional backing or additional backing-binder composite
were placed together onto the pins of a 12 inch by 18 inch tenter
frame. When using additional backing-thermoplastic binder
composites, the tufted backing and composites were brought together
so that the composite surface formed by the binder was in contact
with the stitched side of the tufted backing. The resulting
structures were then passed, pile side down, through the Conveyer
Dryer set at 290.degree. F. (143.degree. C.) for a dwell time of
about 6 minutes. During passage through the dryer, the resin of the
binder melted. Immediately after the 6 minute dwell time, the
structure, with the resin still melted, was removed from the tenter
frame and passed between two smooth steel rolls with a force
applied at the nip. In examples using nylon or polyester face
yarns, force at the nip was 73 pounds per linear inch. In examples
using polypropylene face yarns, force at the nip was 10 to 15
pounds per linear inch.
[0152] Materials from which the stitch bind compositions were
prepared and polymer contents and viscosities of the compositions
as used in the examples are shown in the following table.
TABLE-US-00002 TABLE I Binder Tradename No. Composition or Source 1
30 wt %, 1000 cps dispersion in ammonia Michem-Prime water of
ethylene acrylic acid copolymer 4983-30R (Primacor 5985 from Dow
with nominal 20 wt % acrylic acid units; melt index of 300 g/ 10
min, molecular weight of 18000); as used, solids content was 10-15
wt % and viscosity was 3.3 cps 2 52.5 wt %, 362 cps emulsion in
water of Tylac carboxylated styrene-butadiene copolymer 69809-00
rubber with about 65 wt % bound styrene; as used, polymer content
was 15 wt % and viscosity was 1.6 cps 3 25 wt %, 450 cps dispersion
in water of Experimental maleated polypropylene resin with Tg of
product about 15.degree. C. and nominal molecular weight of 80,000;
as used, polymer content was 10 wt % and viscosity was 10.6 cps 4
52 wt %, 200 cps emulsion in water of self Elite-33 crosslinking
ethylene vinyl acetate copolymer with Tg of 10.degree. C.; as used,
polymer content was 10 wt % and viscosity was <10 cps 5 52 wt %,
100 cps emulsion in water of Dur-O-Set self-crosslinking, ethylene
vinyl acetate E-623 copolymer with Tg of 0.degree. C.; as used,
polymer content was 10 wt % and viscosity was <10 cps 6 44 wt %,
150 cps emulsion in water of Rhoplex crosslinkable, carboxylated
styrene NW-1715K acrylate copolymer with Tg of -6.degree. C.; as
used, polymer content was 10 wt % and viscosity was <10 cps 7 50
wt %, 352 cps emulsion in water of Acronal styrene-n-butyl acrylate
copolymer with S728 Tg of 25.degree. C., believed to have about 50
wt % styrene units and about 50 wt % acrylate units; as used,
polymer content was 15 wt % and viscosity was 1.5 cps 8 51 wt %,
100 cps emulsion in water of Nacrylic acrylic polymer with Tg of
-4.degree. C.; as used, X4280 polymer content was 10 wt % and
viscosity was <10 cps 9 49 wt %, 30 cps emulsion in water with
BFGoodrich synthetic anionic emulsifier of vinyl TN-2000
chloride-acrylic copolymer; as used, polymer content was 15 wt %
and viscosity was <5 cps 10 50 wt %, 615 cps emulsion in water,
Acronal without plasticizers or solvents, of n- S504 butyl
acrylate/acrylonitrile/styrene copolymer with Tg of 4.degree. C.;
as used, polymer content was 10-15 wt % and viscosity at 15 wt %
polymer content was 1.7 cps
EXAMPLES 3-10
[0153] These examples illustrate carpets according to the invention
prepared as described above from woven polypropylene backings and
nylon face yarns, with about 1/2 osy organic polymer or residue and
about 4-6 osy thermoplastic binder, in a loop pile
construction.
[0154] Tufted backings were prepared from solution dyed, 2-ply,
cabled, 3300 denier continuous filament nylon face yarn having 4.8
turns per inch and a primary backing fabric, identified as PolyBac
Fabric Style 2261 from Amoco, woven from polypropylene tapes in a
plain weave construction with 24 warp tapes per inch and 15 weft
tapes per inch. The backing fabric was tufted with the face yarn in
a straight stitch pattern and loop pile construction at 1/8 gauge,
8 stitches per inch and pile weight of 22 osy.
[0155] The additional backing was a 2.43 osy, plain weave secondary
backing fabric woven from polypropylene warp tapes and 1800 denier
polypropylene spun yarns in the weft direction in a 12.times.6
construction.
[0156] The thermoplastic binder was in the form of a layer of
thermoplastic resin coated onto the additional backing. The resin
was a linear low density polyethylene resin, identified as Aspun
6811A from Dow Chemical, having nominal MI of 27 g/10 min at
190.degree. C., density of 0.941 g/cc and melting point of
125.degree. C. The resin was extrusion coated onto the secondary
backing fabric to form a continuous coating on the surface of the
fabric. Coating was conducted on an extrusion coating line using a
two inch diameter, single screw extruder with a twenty inch slot
die having a die gap adjusted within the range of about 10 mils to
provide different coating thicknesses and weights. The extruder was
operated at screw speed settings of 50 rpm, barrel temperature
settings of about 185.degree. C. and die temperature setting of
200.degree. C. The melted resin was extruded onto the fabric
backing about two inches upstream from a stainless steel chill
roll-rubber coated press roll combination with the chill roll
maintained at 30.degree. C. with circulating water. The coated
fabric was passed to a nip between the rolls such that the coating
contacted the chill roll. Force of about 50 pounds per linear inch
was applied at the nip between the rolls. After solidification of
the coating, the resulting secondary backing-thermoplastic binder
composite was taken up on a roll located downstream of the nip roll
pair.
[0157] Fuzz Ratings and Tuft Bind strengths with different stitch
bind compositions, identified with reference to Table 1, as well as
stitch bind polymer and thermoplastic binder contents of the
samples, are reported in the following table. TABLE-US-00003 TABLE
2 Stitch Bind Composition Weight Thermoplastic Fuzz Tuft Bind
Example No. (osy) Binder (osy) Rating (lbs) Control A -- 0 4.9 10
2.3 Control B -- 0 4.2 9 2.0 3 1 0.57 5.0 0 6.1 4 3 0.61 4.6 1 5.1
5 10 0.54 5.4 1 2.7 6 7 0.58 5.0 2 4.6 7 2 0.52 4.9 1 4.2 8 4 0.51
5.4 1 3.3 9 8 0.52 5.5 3 2.7 10 5 0.50 5.3 3 2.6
[0158] As seen from these examples and the table, all of the
samples prepared using the stitch bind compositions showed
significant improvements in Fuzz Ratings as compared to the
Controls. The good Fuzz Ratings were achieved even though the face
yarn used in these examples was a twisted yarn with a compact
structure that hinders good penetration into the interior of the
yarn bundles making up the stitches. In addition, Tuft Bind
strength increased significantly with some of the stitch bind
compositions.
EXAMPLES 11-14
[0159] Example 3 was repeated except that the amount of stitch bind
composition was varied. Results are reported in Table 3.
TABLE-US-00004 TABLE 3 Stitch Bind Composition Weight Thermoplastic
Fuzz Tuft Bind Example No. (osy) Binder (osy) Rating (lbs) Control
A -- 0 4.9 10 2.3 11 1 0.25 4.8 1-5* 4.6 12 1 0.52 4.7 0 5.8 13 1
1.02 4.7 0 6.8 14 1 1.51 4.7 0 7.6 *Results varied for different
areas of the sample; variability is believed to reflect
inconsistent application of organic polymer component to the
stitched backing at the level of polymer used in this example.
[0160] As seen from these examples and the table, in this carpet
construction fuzz resistance at about 1/4 osy was just acceptable
or variable but at about 1/2 osy became superior. Tuft bind
strengths also increased with increasing amounts of stitch bind
polymer 1.
EXAMPLES 15-16
[0161] The procedure of Examples 3-10 was repeated except that the
tufted backing had 2750 denier, nylon 6 continuous filament face
yarns tufted into the primary backing fabric in a loop pile
construction with 1/8 gauge, 8 stitches per inch, a straight stitch
pattern and pile weight of 18 osy. Stitch bind composition No. 6,
as described in Table 1, was used in varying amounts. Fuzz ratings
and Tuft Bind strengths of the resulting samples are reported in
the following table. TABLE-US-00005 TABLE 4 Stitch Bind Composition
Weight Thermoplastic Fuzz Tuft Bind Example No. (osy) Binder (osy)
Rating (lbs) Control C -- 0 5.8 8 4.8 15 6 0.23 5.8 4 5.4 16 6 0.63
4.7 1 5.2
[0162] As seen from these examples and the table, in this carpet
construction, fuzz resistance at about 1/4 osy was acceptable but
was significantly better at about 1/2 osy.
EXAMPLES 17-18
[0163] In these examples, carpet samples were prepared using stitch
bind compositions 1 and 2 and materials otherwise the same as in
Examples 3-10, except that before tufting the primary backing
fabric was needled as in Example 2 with a thermoplastic binder in
the form of a two-ply, 3 osy nonwoven fabric. The nonwoven fabric
binder was prepared from a formulation containing 99 parts by
weight of a linear low density polyethylene resin, identified as
Aspun 6806A from Dow Chemical, having nominal MI of 105 g/10 min at
190.degree. C. and melting point of 125.degree. C., and one part by
weight of a multiphase, thermoplastic elastomeric
polypropylene-polyethylene copolymer, identified as Montell KS-057
having nominal MFR of 30 g/10 min at 230.degree. C.
[0164] Stitch bind polymer and thermoplastic binder contents, Fuzz
Ratings and Tuft Bind strengths of the resulting samples and of a
control made without use of stitch bind composition are reported in
Table 5. Thermoplastic binder amounts shown in the table are weight
of binder coated on the secondary backing plus weight of nonwoven
fabric needled to the primary backing. TABLE-US-00006 TABLE 5
Stitch Bind Composition Weight Thermoplastic Fuzz Tuft Bind Example
No. (osy) Binder (osy) Rating (lbs) Control D -- 0 7.8 9 2.9 17 1
0.47 7.7 0 7.2 18 2 0.51 7.7 0 4.9
[0165] Comparing Control D with Controls A and B, it can be seen
that the additional 3 osy of thermoplastic binder used in these
examples increased Tuft Bind strength but did not improve Fuzz
Rating. Tuft Bind was further improved as a result of use of stitch
bind compositions in Examples 17 and 18. From these results and
those in Examples 3 and 7, in which the same stitch bind
compositions were used, it also can be seen that the presence of
the additional 3 osy of thermoplastic binder did not impair fuzz
resistance imparted by the stitch bind composition. As in examples
3-10, these results are considered impressive in view of the
compact nature of the twisted face yarn of the tufted backing.
EXAMPLES 19-21
[0166] These examples illustrate carpet according to the invention
with cabled nylon BCF yarns tufted in a woven polypropylene backing
in a multi-level loop pile construction with extreme stepover
stitches. This style and these materials are representative of
carpet tiles. Extreme stepover stitching as in this sample makes
good fuzz resistance difficult to achieve.
[0167] Face yarns were a 2880 denier, cabled nylon BCF yarn, a 4150
denier nylon BCF yarn and a 2750 denier nylon BCF yarn. The face
yarns were tufted into a primary backing fabric woven from
polypropylene tapes in a plain weave construction. Face yarns were
tufted in a multi-level, loop pile construction with a stepover
stitch pattern at 1/10 gauge, 11 stitches per inch and pile weight
of 24 osy. Tufting with the three different face yarn types
produced a pile with a patterned effect.
[0168] Carpet samples prepared in these examples also included a
secondary backing which was a fabric woven from polypropylene warp
tapes and 1800 denier polypropylene spun yarn in the weft in a leno
construction with 16 warp tapes per inch and 5 weft yarns per inch
and nominal weight of 2.1 osy.
[0169] Thermoplastic binder was used in the form of a 9.5 mil thick
coating on the secondary backing. The binder had the same
composition and was applied to the secondary backing fabric as in
Examples 3-10.
[0170] Stitch bind polymer and thermoplastic binder weights, Fuzz
Ratings and Tuft Bind strengths of the resulting samples are
reported in Table 6. TABLE-US-00007 TABLE 6 Stitch Bind Composition
Weight Thermoplastic Fuzz Tuft Bind Example No. (osy) Binder (osy)
Rating (lbs) Control E -- 0 6.6 8 4.6 19 1 1.0 6.6 2 6.7 20 7 1.0
6.6 2 6.3 21 2 1.0 6.6 3 6.2
[0171] As seen from the table, in this carpet construction, use of
the stitch bind composition resulted in significant improvements in
Fuzz Ratings and Tuft Bind as compared to the control. These
results are considered surprising in view of difficulties in
achieving good fuzz resistance in carpet constructions of this
type, as noted above.
EXAMPLES 22-27
[0172] These examples illustrate effectiveness of the invention in
carpets tufted with polypropylene face yarn in a typical commercial
carpet style.
[0173] Tufted backings were prepared with a loop pile and straight
stitch pattern with 1/10 gauge, 10 stitches per inch and pile
weight of 20 osy. Face yarn was 2750 denier, pigmented
polypropylene BCF yarn. The face yarn was tufted into a primary
backing fabric, identified as PolyBac Fabric Style 2205, of woven
polypropylene tapes in a 24.times.13 plain weave construction.
[0174] These examples also used a secondary backing
fabric-thermoplastic binder composite as in Examples 3-10.
[0175] Stitch bind polymer and thermoplastic binder weights, Fuzz
Ratings and Tuft Bind strengths of the resulting samples are
reported in Table 7. TABLE-US-00008 TABLE 7 Stitch Bind Composition
Weight Thermoplastic Fuzz Tuft Bind Example No. (osy) Binder (osy)
Rating (lbs) Control F -- 0 4.2 8 3.7 22 1 0.59 4.5 3 7.7 23 3 0.49
4.2 1 8.1 24 4 0.51 4.2 3 5.7 25 8 0.51 4.4 3 3.4 26 10 0.57 4.2 2
8.1 27 6 0.57 4.1 5 4.4
[0176] As seen from these examples, all of the stitch bind
compositions were effective in reducing fuzzing and all but one
also increased tuft lock of this polypropylene face yarn-tufted
carpet. Fuzz Ratings improved significantly in all cases except
with the styrene-acrylate copolymer dispersion in Example 27.
EXAMPLES 28-30
[0177] These examples illustrate carpets according to the invention
constructed in a Berber pattern. Berber patterns have significantly
larger face yarn bundles than many other carpet styles, which
typically is conducive to good Tuft Bind strength with
thermoplastic binders but detrimental to fuzz resistance. Fuzz
resistance of Berber carpets made with conventional latex binders
is also difficult to achieve.
[0178] Face yarns used to prepare tufted backings were 16,800
denier, entangled, pigmented polypropylene BCF yarns. The backing
was a primary backing fabric woven from polypropylene tapes in a
24.times.11 plain weave. The face yarn was tufted in a multilevel
loop construction with a wiggle stitch pattern at 1/4 gauge, 5.5
stitches per inch and 45 osy pile weight.
[0179] In these examples the secondary backing fabric-thermoplastic
binder composite as in Examples 3-10 was also used.
[0180] Stitch bind polymer and thermoplastic binder weights, Fuzz
Ratings and Tuft Bind strengths of the resulting samples are
reported in Table 8. TABLE-US-00009 TABLE 8 Stitch Bind Composition
Weight Thermoplastic Fuzz Tuft Bind Example No. (osy) Binder (osy)
Rating (lbs) Control G -- 0 5.0 10 10.0 28 1 1.0 5.0 4 16.1 29 7
1.5 5.0 4 17.1 30 9 1.5 5.0 6 14.8
[0181] As seen from the table, fuzz resistance increased in the
Berber carpet samples according to the invention. Weights of stitch
bind polymer in these samples exceeded those in most other examples
due to the large yarn bundles, but were still minor relative to
overall carpet weight and provided surprising improvements in Fuzz
Ratings.
EXAMPLES 31-36
[0182] In these examples, carpets according to the invention were
made with polyester face yarn in a cut pile construction
representative of residential carpets.
[0183] Tufted backings were prepared from cabled, stuffer
box-crimped, heat set, 2-ply polyester (polyethylene terephthalate)
spun yarns with 4400 total denier and 5.5 turns per inch. The yarns
were tufted into a woven primary backing fabric as used in Examples
22-27 in a cut pile construction with a stepover stitch, 1/8 gauge,
8 stitches per inch, pile height of 1/2 inch and pile weight of 40
osy. The secondary backing fabric-thermoplastic binder composite as
in Examples 3-10 was also used. Stitch bind polymer contents,
thermoplastic binder weights and Tuft Binds are reported in Table
9. TABLE-US-00010 TABLE 9 Stitch Bind Composition Weight
Thermoplastic Fuzz Tuft Bind Example No. (osy) Binder (osy) Rating
(lbs) Control H -- 0 4.2 -- 3.2 31 1 0.57 4.4 -- 3.9 32 3 0.63 4.6
-- 2.7 33 4 0.53 4.4 -- 4.2 34 8 0.53 4.2 -- 2.1 35 6 0.59 4.3 --
3.2 36 10 0.53 4.3 -- 3.5
[0184] This example demonstrates results with this polyester face
yarn-tufted carpet according to the invention. Fuzz Ratings were
not obtained for these samples because the Velcro roller doesn't
cause fuzzing suitable for evaluation on cut pile carpets. For an
indication of fuzzing, samples were subjected to a non-standardized
test known as the "coin rub test." In that test, a US quarter
dollar coin was rubbed by hand back and forth for 5 seconds on a
small area, about 2 inches by 2 inches, of the carpet samples and
the amount of fuzz kicked up due to the rubbing was assessed.
Although the test is poor for comparison of different samples
because the intensity of rubbing is not standardized, coin rub test
results for the samples made using the stitch bind composition
generally indicated significantly better fuzz resistance than for
the control.
EXAMPLE 37
[0185] In this example, a carpet according to the invention was
prepared with wool face yarn.
[0186] The tufted backing had a woven primary backing fabric of
polypropylene tapes in a 28.times.24 plain weave construction to
which had been needled a thermoplastic binder in the form of a 4.5
osy continuous filament nonwoven fabric as in Examples 17-18. The
primary backing-binder composite was tufted with a 2900 denier, 3
turns per inch twisted yarn spun from 80 wt % wool and 20 wt %
nylon fiber in a cut pile, straight stitch pattern with 1/10 gauge,
10 stitches per inch and 1/4 inch pile height.
[0187] Heating time to melt the resin of the thermoplastic binder
was 81/2 minutes in this example.
[0188] The secondary backing fabric-thermoplastic binder composite
as in Examples 3-10 was also used. Nip force applied to the
intermediate carpet with melted thermoplastic binder resin was 50
pounds per linear inch.
[0189] Stitch bind polymer contents, thermoplastic binder weights
and Tuft Bind strengths of the resulting samples are reported in
Table 10. Thermoplastic binder weights reported in the table are
weights of coating on the secondary backing plus nonwoven fabric
needled to the primary backing. TABLE-US-00011 TABLE 10 Stitch Bind
Composition Weight Thermoplastic Fuzz Tuft Bind Example No. (osy)
Binder (osy) Rating (lbs) Control I -- 0 9.0 -- 1.4 37 1 0.5 9.0 --
2.6
[0190] As seen from the table, Tuft Bind strength of the carpet
sample according to the invention was almost double that of the
control. However, the low Tuft Bind strengths for both the control
and example as compared to other examples reflect the relatively
small yarn bundle size of the face yarn used in this example and
the fact that wool yarns are generally less conducive to bonding
with thermoplastic binders than synthetic yarns. Coin rub test
results indicated that fuzz resistance was better in the example
than in the control.
EXAMPLE 38
[0191] A tufted backing was prepared in a cut pile construction,
1/8 gauge, with a stepover stitch pattern, 8 stitches per inch,
pile height of 1/2 inch and pile weight of 42 osy, from a woven
polypropylene primary backing as in Examples 22-27 and a 2-ply
cabled nylon BCF yarn.
[0192] The tufted primary backing was passed pile side down to a 90
feet long carpet finishing oven preheated to 220.degree. F.
(104.degree. C.) at a speed of 15 ft per minute. Just prior to
entering the oven, the stitched side of the tufted primary backing
was sprayed with a stitch bind composition as in Table 1, No. 1,
except that polymer solids had been diluted to 10 wt % and
viscosity was 2.2 cps. The spray was applied at a rate of about 5
osy. The treated backing was passed through the oven; residence
time was about 6 minutes. The dried tufted backing had an average
stitch bind polymer content of about 0.5 osy disposed as a
discontinuous coating and agglomerates on and within the stitches
on the stitched side such that filaments of most of the stitches
were bonded.
[0193] The tufted backing with bonded filaments was then combined
with a composite of a secondary backing as in Examples 3-10 that
had been extrusion coated with a thermoplastic binder in the form
of a 4.5 osy layer of the linear low density polyethylene resin
used in Examples 3-10. The tufted backing and secondary
backing-binder composite were brought together so that the binder
contacted the stitched side of the tufted backing. The resulting
intermediate structure was run pile side up through a 120 feet
long, forced air oven at 30 feet per minute and oven air
temperature of 335.degree. F. (168.degree. C.) Immediately after
the carpet exited the oven, it was passed through a driven nip roll
set where a nip force of 70 pounds per linear inch was applied. The
carpet was allowed to cool for about 10 minutes and then was taken
up on a roll. The finished carpet had an average Tuft Bind strength
of 4.7 lbs and good fuzz resistance by the coin rub test.
[0194] For comparison, the procedure described above was repeated
except the tufted backing was contacted with the secondary
backing-binder composite without application of stitch bind
dispersion or drying. The resulting finished carpet had a lower
Tuft Bind strength (3.6 pounds) and was less resistant to fuzzing
in the coin rub test than when the stitch bind composition was
used.
EXAMPLE 39
[0195] Following the procedures, and using a tufted backing, stitch
bind dispersion, spray applicator and oven as in Example 1, the
dispersion is sprayed onto the stitches of the tufted backing and
then dried in the oven. The resulting tufted backing has filaments
of a plurality of its stitches bonded with about 1/2 osy ethylene
acrylic acid copolymer in the form of a discontinuous coating on
and penetrating into the stitches. The result is taken up on a
roll.
[0196] In a separate operation, the tufted backing with adhered
filaments is unwound and fed into contact with a secondary
backing-thermoplastic binder composite as in Example 1. The
resulting intermediate structure is advanced into an oven and
heated as in Example 1 to melt the resin of the binder coated onto
the secondary backing. The result, with the resin of the coating
still melted, is advanced to a nip system as in Example 1, force of
30 pounds per linear inch is applied and the result is cooled and
taken up.
[0197] The resulting carpet has properties similar to the carpet of
Example 1.
EXAMPLE 40
[0198] A tufted backing as in Example 1 with stitch bind
composition applied and dried as in that example is extrusion
coated across the full width of its stitched side with a melted
film of linear low density polyethylene resin having nominal MI of
27 g/10 min, density of 0.941 g/cc and melting point of 125.degree.
C. to form an 8.5 osy, 9.5 mil thick layer of the resin coated onto
the tufted backing. Extrusion coating is conducted using single
screw extruder with a slot die and operated at screw speed of 59
rpm, extruder barrel temperature setting of 185.degree. C., die
temperature of 200.degree. C. and die gap of 10 mils. The melted
resin is coated onto the tufted backing about two inches upstream
from a stainless steel chill roll-rubber coated press roll
combination with the chili roll maintained at 30.degree. C. with
circulating water. The coated structure advances into the nip
between the rolls such that the coating contacts the chill roll and
the pile side contacts the press roll. Force of 50 pounds per
linear inch is applied at the nip between the rolls to press the
melted resin into the stitched side without compressing the tufts
making up the pile surface. The coating cools to solidify the resin
shortly downstream of the roll pair and is taken up.
[0199] The resulting carpet has good fuzz resistance and tuft bind
strength. Comparable results are attained when a secondary backing
in the form of a 16.times.5 leno weave fabric of polypropylene warp
tapes and polypropylene spun weft yarns is unwound from a roll and
advanced into the nip between the press roll and the chill roll so
that it contacts the melted resin extruded onto the tufted backing
at the nip.
EXAMPLE 41
[0200] A tufted primary backing as in Example 1 is sprayed with
stitch bind composition according to Table 1, No. 1, and then dried
in a forced air oven as in Example 1. The amount of organic polymer
in the dried product is about 1/2 osy. The dried, tufted backing
having filaments of a plurality of its stitches bonded with the
organic polymer is taken up on a roll.
[0201] In a separate operation, the tufted backing with bonded
filaments is unwound and passed pile side down through an oven with
infrared heaters positioned about 12 inches above the surface of
the stitched side. A uniform coating of low density polyethylene
powder with density of 0.92 g/cc, MI of 3 g/10 min and melting
point of 108.degree. C. is sprinkled onto the stitched side as the
tufted backing passes through the oven. The amount of polyethylene
powder is 5 osy. The belt speed and power to the heaters are
adjusted so that the polyethylene powder melts and reaches a
temperature of 270.degree. F. Immediately prior to exiting the
oven, a woven secondary backing as in Example 40 is advanced into
contact with the stitched side of the tufted primary backing with
the polyethylene powder still melted. The resulting laminate of
melted resin disposed between the secondary backing and the
stitched side of the tufted primary backing is passed out of the
oven to and through a pair of steel nip rolls that apply a force of
30 pounds per linear inch. The result is allowed to cool for about
four minutes and is then taken up on a roll. The resulting carpet
has properties similar to the carpet of Example 1.
* * * * *