Note: Descriptions are shown in the official language in which they were submitted.
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FLOOR COVERING CONTAINING POLYVINYL BUTYRAL AND
METHOD OF MAKING SAME
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application
60/568,966 filed May 6, 2004.
BACKGROUND
Carpets and other floor coverings may include one or more components
that are formed from recycled or reclaimed thermoplastic polymeric materials
that contain volatile organic compounds (VOC's). Carpets and floor coverings
including such recycled or reclaimed thermoplastic polymeric materials must
meet stringent limits on the level of VOC's emitted from the products.
SUMMARY
According to one aspect of the present invention, a reinforced foam
backing for a floor covering such as, for example, carpet, includes a foam
sheet
comprising polyvinyl butyral. The foam sheet has a plurality of cells formed
therein, and at least one reinforcing material joined with the foam sheet. The
polyvinyl butyral may comprise recycled polyvinyl butyral, virgin polyvinyl
butyral, or any combination thereof.
According to another aspect of the invention, a floor covering comprises
a carpet including a plurality of textile fibers at least partially embedded
in a
polymeric pre-coat layer comprising a polyurethane, and a foam backing
comprising polyvinyl butyral attached to the carpet.
According to yet another aspect, a floor covering includes a backing
comprising recycled polyvinyl butyral. The floor covering has a total volatile
organic compound emission factor of less than about 1 mg/m2/hr as measured
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according to ASTM D-5116-1990. The backing used in the floor covering may
be a foam.
According to still another aspect of the invention, a floor covering
comprises a carpet including a plurality of textile fibers, a foamed backing
including polyvinyl butyral joined to the carpet, and a polymeric pre-coat
layer
joining the carpet to the foamed backing. The floor covering has a total
volatile
organic compound emission factor of less than about 0.5 mg/m2/hr as measured
according to ASTM D-5116-1990. The polymeric pre-coat layer may include a
polyurethane, polyvinyl butyral, polyvinyl chloride, or any combination
thereof.
The invention also contemplates a method of manufacturing a floor
covering. The method includes extruding a polymeric material mixture
comprising molten polyvinyl butyral and a blowing agent or cell-forming
material, calendering the extruded polymeric mixture to form a sheet, and
heating the sheet to form a foamed polyvinyl butyral backing.
The invention further contemplates a method of making floor covering
including a recycled PVB foam backing. The floor covering has a total volatile
organic compound emission factor of less than about 0.5 mg/m2/hr as measured
according to ASTM D-5116-1990. The method includes extruding a polymeric
material mixture comprising molten recycled polyvinyl butyral and a cell-
forming material, calendering the extruded polymeric mixture to form a sheet,
and heating the sheet to form a foamed polyvinyl butyral backing, where at
least one of the extruding, calendering, and heating are carried out at a
temperature sufficient to release volatile organic compounds from the
polymeric material mixture.
These and other aspects are set forth in greater detail in the detailed
description below and in the accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a cross-sectional view of an exemplary foam-backed
tufted carpet according to various aspects of the present invention;
FIG. 2 depicts a cross-sectional view of an exemplary foam-backed
woven carpet according to various aspects of the present invention;
FIG. 3 depicts an exemplary processing line for manufacturing foam
backing products according to various aspects of the present invention;
FIG. 4 depicts an exemplary calender unit that may be used in the
processing line of FIG. 3;
FIG. 5A depicts a partial perspective view of an exemplary reinforced
calendered sheet that is an intermediate product of a process for forming a
floor
covering, according to various aspects of the present invention;
FIG. 5B depicts a cross-sectional view of a portion of the reinforced
calendered sheet of FIG. 5A;
FIG. 6 depicts another exemplary calender unit that may be used in a
processing line for manufacturing foam backing products, according to various
aspects of the present invention;
FIG. 7 depicts another exemplary calender unit that may be used in a
processing line for manufacturing foam backing products, according to various
aspects of the present invention;
FIG. 8 depicts a cross-sectional view of another exemplary cushioned
floor covering according to various aspects of the present invention;
FIG. 9 depicts a cross-sectional view of yet another exemplary
cushioned floor covering according to various aspects of the present
invention;
FIG. 10 depicts a cross-sectional view of still another exemplary
cushioned floor covering according to various aspects of the present
invention;
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FIG. 11 depicts another exemplary processing line for manufacturing
foam backing products, according to various aspects of the present invention;
and
FIG. 12 depicts a cross-sectional view of yet another exemplary
cushioned floor covering according to various aspects of the present
invention.
DETAILED DESCRIPTION
Various aspects of the present invention relate to a composition for
forming a backing for a floor covering, a floor covering including such a
backing, a method of making a backing for a floor covering, and a method of
making a floor covering including such a backing. Some of such aspects
employ polyvinyl butyral (PVB). Some of such aspects employ recycled
materials, virgin (non-recycled) materials, or a combination thereof.
The various aspects of the present invention may be used in connection
with numerous types of floor coverings, for example, tufted carpets, woven
carpets, tufted carpet tiles, woven carpet tiles, rugs, and flooring tiles. By
way
of example, and not by way of limitation, carpet is described in detail
herein.
However, it should be understood that the various aspects of the invention
have
broad utility with numerous types of floor coverings, such as vinyl, wood, and
composite floor coverings.
With reference to FIG. 1, an exemplary cushion-backed tufted carpet
100 generally comprises tufted pile yams 102 that are looped through a primary
backing 104. The pile yarns 102 may be cut to form cut pile tufts as
illustrated
in FIG. 1 or may be left in uncut loops. A pre-coat layer 106 may be used to
secure the pile yams 102 on or within the primary backing 104. A secondary
backing 110 may be adhered to the pre-coat layer 106.
The primary backing 104 may be formed using a variety of techniques.
In one aspect, the primary backing 104 is a woven material formed by weaving
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synthetic fibers, such as polypropylene, polyethylene, nylon, polyester, PLA
or
any combination thereof. In another aspect, the primary backing 104 is a
nonwoven fabric, for example, a spunbond, meltblown, or needlepunched
material. Any of the materials used to form the primary backing 104, whether
woven, nonwoven, or a combination thereof, may be formed from bicomponent
fibers having a sheath/core or side by side configuration.
The pre-coat layer 106 may be applied to the textile material using any
suitable technique that allows the pre-coat layer to cure, film form, or fuse
to
the textile material. In one aspect, the pre-coat layer is applied to the
carpet
using extrusion coating techniques. In another aspect, the pre-coat is applied
as
a dispersion. In yet another aspect, the pre-coat is applied as a hot melt.
However, other processes are contemplated hereby.
The pre-coat layer or backcoating 106 may be formed from any material
that secures the pile yarns 102 on or within the primary backing 104. In one
aspect, the pre-coat layer 106 comprises a polymeric material. For example,
the
pre-coat layer 106 may comprise an ethylene/vinyl acetate copolymer, polyvinyl
butyral, a polyurethane, polyvinyl chloride, a tackified polyolefin, or any
combination thereof. One example of a polyurethane that may be suitable for
use with the present invention is DOW 605.01, commercially available from
Dow Chemical Company (Midland, Michigan).
The polymer used to form the pre-coat layer may have a glass transition
temperature of from about -15 C to about 10 C. In another aspect, the polymer
used to form the pre-coat layer has a glass transition temperature of from
about
-10 C to about 5 C. In yet another aspect, the polymer used to form the pre-
coat layer has a glass transition temperature of from about -5 C to about 0 C.
Thus, in one particular aspect, the pre-coat layer comprises a polyurethane
having a glass transition temperature of from about -5 C to about 0 C.
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The polymer used to form the pre-coat layer may have a tensile strength
of from about 1500 to about 5000 psi. In one aspect, the polymer used to form
the pre-coat layer has a tensile strength of from about 1700 to about 4000
psi.
In yet another aspect, the polymer used to form the pre-coat layer has a
tensile
strength of from 2000 to about 3500 psi. Thus, in one particular example, the
pre-coat layer may comprise a polyurethane having a tensile strength of from
2500 to about 3000, for example, about 2840 psi.
The polymer used to form the pre-coat layer may have an ultimate
elongation of from about 700 to about 850%. For instance, the ultimate
elongation may be from about 725 to about 825%, or from about 750 to about
800%, for example, about 776%. The polymer used to form the pre-coat layer
may have a stress at 100% modulus of from about 200 to about 400 psi, or from
about 250 to about 300 psi, for example, 290 psi. Thus, in one particular
example, the pre-coat layer may comprise a polyurethane having an ultimate
elongation of from about 750 to about 800% and a stress at 100% modulus of
from about 250 to about 300 psi.
A polyurethane used in accordance with the present invention may be
applied as an aqueous dispersion, or as a molten polymer using, for example,
extrusion coating. Where applied as a dispersion, the dispersion may have any
suitable solids or non-volatiles content. In one aspect, the polyurethane
dispersion has a solids content of from about 6.0 to about 70%. In another
aspect, the polyurethane dispersion has a solids content of from about 50 to
about 60%. In another aspect, the polyurethane dispersion has a solids content
of from about 40 to about 50%. In another aspect, the polyurethane dispersion
has a solids content of from about 30 to about 40%. In another aspect, the
polyurethane dispersion has a solids content of from about 20 to about 30%.
Polyvinyl butyral used in accordance with the present invention may be
applied as an aqueous dispersion, as a molten polymer using, for example,
extrusion coating, or as a tackified hot melt. Where applied as a dispersion,
the
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dispersion may have any suitable solids or non-volatiles content. In one
aspect,
the polyvinyl butyral dispersion has a solids content of from about 20 to
about
80%. In another aspect, the polyvinyl butyral dispersion has a solids content
of
from about 70 to about 80%. In another aspect, the polyvinyl butyral
dispersion
has a solids content of from about 60 to about 70%. In another aspect, the
polyurethane polyvinyl butyral has a solids content of from about 50 to about
60%. In another aspect, the polyvinyl butyral dispersion has a solids content
of
from about 40 to about 50%. In another aspect, the polyvinyl butyral
dispersion
has a solids content of from about 30 to about 40%. In another aspect, the
polyvinyl butyral dispersion has a solids content of from about 20 to about
30%.
While various polyurethane and polyvinyl butyral dispersions are
provided herein, it will be understood that the optimum level of solids
typically
depends on the kind of equipment being used and the kind and amount of other
components in the formulation. If inorganic fillers and flame retardants are
used, they typically are dispersed in the water phase. The more filler needed,
the lower the solids that are needed to wet out and disperse the fillers.
However, if the solids content is very low, additional drying is needed and
the
linear speed through the drying oven may need to be decreased to a point where
the economics of manufacture are not justified.
The polymeric pre-coat generally may be present in an amount of from
about 5 to about 40 wt % based on the weight of the carpet (dry/dry basis). In
one aspect, the polymeric pre-coat is present in an amount of from about 10 to
about 35 wt % based on the weight of the carpet (dry/dry basis). In another
aspect, the polymeric pre-coat is present in an amount of from about 15 to
about
wt % based on the weight of the carpet (dry/dry basis). In yet another
aspect, the polymeric pre-coat is present in an amount of from about 20 to
about
25 wt % based on the weight of the carpet (dry/dry basis).
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FIG. 2 illustrates an exemplary cushion-backed woven floor covering
200 having a woven carpet layer 202, a back-coating or resin composition layer
208, a backing layer 210 having cells 212 formed therein, and an optional
pressure self-release adhesive layer 220 with a releasable liner 222. The
woven
carpet layer 202 is formed by weaving warp yams 204 and weft yams 206 to
provide a decorative face surface. The cushioned woven floor covering 200
may be a rolled carpet or cut in the shape of a tile.
The secondary backing (also referred to herein as "backing") 110, 210
comprises any suitable material, and in some instances, comprises a flexible
polymeric matrix. The backing 110, 210 typically serves as a resilient cushion
that will compress under an external load and recover when the load is
removed. According to various aspects, the backing 110, 210 may be an open
cell structure, a partially or substantially closed cell structure, or a
closed cell
foam. In general, the greater the percentage of closed cells in the structure,
the
better the cushioning properties of the backing. While the use of foam
backings is described in detail herein, it should be understood that non-foam
backings also may be used, as will be described in greater detail below.
In the exemplary structure shown in FIGS. 1 and 2, the backing 110,
210 comprises a closed cell foam including a plurality of gas pockets or cells
112, 212. The cells 112, 212 may be voids or may contain air or gases, such as
decomposition products of foaming/blowing agents, as will be discussed in
detail below. The secondary backing 110, 210 may be bonded or otherwise
joined to the adjacent layer or layers 106, 208 using any suitable technique,
for
example, heat lamination, adhesive, stitching, or otherwise.
According to one aspect of the invention, the backing 110, 210
comprises polyvinyl butyral (PVB). In another other aspect, the backing 110,
210 comprises PVB foam. The PVB may be recycled from other products or
materials, may be virgin, or may be a combination thereof. Optionally, as
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shown in FIGS. 5A, 5B, 8, 9, 10 and 12, the backing 110, 210 includes a
reinforcement material or layer 82. In one aspect, the reinforcement layer is
positioned between layer 106, 208 and the backing 110, 210. In another aspect,
the reinforcement layer is at least partially embedded in backing 110, 210. In
yet another aspect, the reinforcement layer is positioned adjacent the backing
on
the side distal from layer 106, 208.
In this and other aspects of the present invention, the reinforcing
material 82 may be veil, scrim, tissue, felt, nonwoven, or other planar
textile
fabric that has been created using a weaving, knitting, nonwoven, or other
textile manufacturing process. For example, the reinforcing materia182 may be
an open weave scrim. As another example, the reinforcing material 82 may be
knitted fabric including a weft inserted knit. As yet another example, the
reinforcing material 82 may be a cross-laid scrim including an over/under laid
scrim or a triaxial laid scrim.
The reinforcing material 82 may be formed from any polymer (e.g.
polyester) fibers, or glass fibers, any other suitable material or combination
of
materials that enhances the strength and/or dimensional stability of the
backing
and that does not melt or soften in the expansion oven. While the use of
reinforced backings is described in detail herein, it will be understood that
non-
reinforced backings also find -broad utility with various other aspects of the
present invention.
The invention also contemplates numerous methods of forming a floor
covering. In one aspect, the present invention contemplates a floor covering
including a foam backing. In another aspect, the invention contemplates a
method of forming a carpet backing from recycled materials, virgin materials,
or a combination thereof. In yet another aspect, the invention contemplates a
method of forming a flooring product that has an emission factor of less than
or
equal to 1 mg/m2/hr total VOC's as measured using ASTM D-5116-1990 titled
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"Small-Scale Environmental Chamber Determinations of Organic Emissions
from Indoor Materials/Products."
FIG. 3 depicts an exemplary process for manufacturing a foam backing
for a floor covering. The composition used to form the backing may be housed
in a feeder 55 or other suitable vessel. In one aspect, the composition
includes
a polymeric material, for example, PVB. The PVB in the composition may
comprise waste material, virgin material, or any combination thereof. The
waste PVB material may be surplus material produced in other processes in
making carpet or other products or may be material that is recycled from other
products after use. The PVB component of the backing formulation may
include up to 100% by weight waste PVB material, up to 100% by weight
virgin PVB material, or any combination of waste and virgin material.
In one aspect, the PVB material may comprise from about 90 to about
100 wt % waste PVB and from 0 to about 10 wt % virgin PVB material. In
another aspect, the PVB material may comprise from about 80 to about 90 wt %
waste PVB and from about 10 to about 20 wt % virgin PVB material. In
another aspect, the PVB material may comprise from about 70 to about 80 wt %
waste PVB and from about 20 to about 30 wt % virgin PVB material. In
another aspect, the PVB material may comprise from about 60 to about 70 wt %
waste PVB and from about 30 to about 40 wt % virgin PVB material. In
another aspect, the PVB material may comprise from about 50 to about 60 wt %
waste PVB and from about 40 to about 50 wt % virgin PVB material. In yet
another aspect, the PVB material may comprise from about 40 to about 50 wt %
waste PVB and from about 50 to about 60 wt % virgin PVB material. In yet
another aspect, the PVB material may comprise from about 30 to about 40 wt %
waste PVB and from about 60 to about 70 wt % virgin PVB material. In still
another aspect, the PVB material may comprise from about 30 to about 40 wt %
waste PVB and from about 60 to about 70 wt % virgin PVB material. In yet
another aspect, the PVB material may comprise from about 20 to about 30 wt %
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waste PVB and from about 70 to about 80 wt % virgin PVB material. In still
another aspect, the PVB material may comprise from about 10 to about 20 wt %
waste PVB and from about 80 to about 90 wt % virgin PVB material. In yet
another aspect, the PVB material may comprise from 0 to about 10 wt % waste
PVB and from about 90 to 100 wt % virgin PVB material.
Waste PVB material may be obtained from a variety of sources for use
with various aspects of the present invention. The composition of PVB scrap
material may vary depending upon its source. While certain compositions are
described in detail herein, it will be understood that numerous other
compositions are contemplated hereby.
In one aspect, waste PVB material may be recovered from automobile
windshields. An exemplary sample of waste PVB material taken from an
automobile windshield may include from:
about 65% to about 90% by weight PVB polymer;
0% to about 35% by weight tetraethylene glycol di-n-heptanoate;
0% to about 35% by weight di-n-hexyl adipate;
0% to about 35% by weight dibutyl sebacate;
0% to about 35% by weight triethylene glycol dihexanoate;
0% to about 35% by weight triethylene glycol di-n-heptanoate;
0% to about 35% by weight triethylene glycol di-2-ethyl-hexanoate;
0% to about 35% by weight tetraethylene glycol di-n-heptanoate; and
0% to about 10% by weight calcium carbonate.
While use of PVB is described in detail herein, it should be understood
that various other waste polymeric materials may be used as desired. Examples
of such materials include, but are not limited to, one or more of a wide
variety
of thermoplastic materials, such as polyolefins (e.g., polyethylene and
polypropylene), polymers based on vinyl monomers (e.g., vinyl esters, such as
vinyl acetate), polymers based on acrylic monomers (e.g., acrylic acid, methyl
acrylic acid, esters of these acids, and acrylonitrile), other thermoplastic
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polymers, blends and copolymers thereof, and any combination thereof. A
variety of fibrous polymeric materials also may be included in the mixture.
Other additives also may be included in the composition. Examples of
such additives include, but are not limited to, extenders or fillers, blowing
agents, processing aids, plasticizers, foaming agents, pigments, antioxidants,
antimicrobial agents, cross-linking agents, flame retardants, polymer
stabilizers,
and the like.
Examples of fillers that may be suitable for use in the backing
composition include, but are not limited to, pulverized glass and other glass
based materials, metallic and magnetic materials, ATH, fly ash, coal ash,
other
ash products resulting from energy generation facilities or incineration,
carbon
black, wollastonite, solid microspheres, hollow microspheres, kaolin, clay-
based minerals, bauxite, calcium carbonate, feldspar, nepheline syenite,
barium
sulfate, titanium dioxide, talc, pyrophyllite, quartz, natural silicas, such
as
crystalline silica, microcrystalline silica, synthetic silicates, such as
calcium
silicate, zirconium silicate, and aluminum silicate (including mullite,
sillimanite, cyanite, andalusite, and synthetic alkali metal
aluminosilicates),
microcrystalline novaculite, diatomaceous silica, perlite, synthetic silicas,
such
as fumed silica and precipitated silicas, antimony oxide, bentonite, mica,
vermiculite, zeolite, and combinations of metals with various salts, such as
calcium, magnesium, zinc, barium, aluminum combined with oxide, sulfate,
borate, phosphate, carbonate, hydroxide, and the like, and any combination
thereof.
Other fillers that can be included in the backing formulations include
organic materials such as bagasse fillers, recycled paper fillers, coconut
hull/fiber fillers, cork fillers, coin cob fillers, cotton-based fillers,
gilsonite
fillers, nutshell fillers (such as peanuts), rice hull fillers, sisal fillers,
hemp
fillers, soybean fillers, starch fillers, wood flour fillers, animal fibers
such as
turkey feather fibers, and any combination thereof.
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Likewise, one or more antioxidants or heat stabilizers may be included
in the backing formulation to prevent polymer degradation and for other
purposes. BHT (2,6-di-t-butyl-p-cresol), phosphite antioxidants, such as TNPP
(tris(mono-nonyl phenyl)phosphite), hindered phenolic antioxidants, such as
tetrakis[methylene-3(3',5'-di-tert-butyl-4-hydroxy phenyl)propionate]methane,
and thioesters, such as DLTDP, DSTDP, DTDTDP, or any combination
thereof, may be used along with other antioxidants or heat stabilizers.
One or more flame retardants also may be included in the backing
formulation. Examples of flame retardants that may be suitable include, but
are
not limited to, ATH, magnesium hydroxide, boron compounds, zinc borate,
AOM, halogenated flame retardants, such as deca-DBP, PBDPO, TBBPA,
HBCD, TBPA, antimony trioxide, phosphorus compounds, such as red
phosphorus, ammonium polyphosphate, triphenyl phosphate, resorcinol
diphosphate, bisphenol A diphosphate, 2-ethyl hexyl diphenyl phosphate,
nitrogen containing compounds, mica, and any combination thereof.
The backing formulations also rimay include one or more plasticizers.
Examples of plasticizers that may be suitable include, but are not limited to,
aromatic diesters such as DINP, DIDP, L9P, DOTP, DBP, DOP, BBP, DHP,
aliphatic diesters such as DINA, DIDA, DHA, aromatic sulfonamides such as
BSA, aromatic phosphate esters such as TCP and TXP, Alkyl phosphate esters
such as TBP and TOF, dialkylether aromatic esters such as DBEP, dialkylether
diesters, tricarboxylic esters, polymeric polyester plasticizers, polyglycol
diesters, alkyl alkylether diesters such as DBEG, DBEA, DBEEG, and DBEEA,
aromatic trimesters such as TOTM and TIOTM, epoxodized esters, epoxidized
oils such as ESO, chlorinated hydrocarbons or parrafins, aromatic oils,
alkylether monoesters, naphthenic oils, alkylmonoesters, glyceride oils,
paraffinic oils, and silicone oils. Linseed oils, citrate plasticizers such as
tributyl citrate, process castor oil, raw castor oil, derivatives of castor
oil such
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as butyl ricinoleate, sebacate plasticizers such as dibutyl sebacate, and any
combination thereof also may be used.
One or more pigments also may be included in the backing formulation.
Examples of pigments that may be suitable include, but are not limited to,
carbon black, titanium dioxide, and any combination thereof.
One or more lubricants may be included in the backing formulation.
Examples of lubricants include, but are not limited to, derivatives of fatty
acids,
calcium stearate, zinc stearate, stearic acid, saturated and unsaturated fatty
primary monoamides, fatty glicerides such as C 14-C 18 mono- and
di-glycerides, and any combination thereof.
If desired, the backing formulation also may include one or more cross-
linking agents such as phenolics, dialdehydes, - aziridines, isocyanates, and
melamines, or any combination thereof.
Thus, according to one aspect of the present invention, the backing
formulation may comprise from about 35 to about 99 wt % PVB (including
virgin and/or waste PVB material), about 0 to about 50 wt % filler, from about
0.1 to about 5 wt % blowing agent, and from 0 to about 5 wt % processing aid.
According to another aspect of the present invention, the backing formulation
may comprise from about 40 to about 80 wt % PVB , from about 20 to about 25
wt % filler, from about 0.5 to about 5 wt % blowing agent, and from 0 to about
1 wt % release aid, such as calcium stearate. According to yet another aspect
of
the present invention, the backing formulation may comprise from about 50 to
about 60 wt % PVB, from about 17 to about 25 wt % plasticizer, from about 0.3
to about 0.8 wt % blowing agent, from about 17 to about 25 wt % calcium
carbonate filler, and from about 0.5 to about 0.8 wt % calcium stearate. In
one
particular aspect, the backing formulation may comprise about 53.7 wt % PVB,
about 22.8 wt % plasticizer, about 0.5 wt % blowing agent, about 22.2 wt %
calcium carbonate filler, and about 0.8 wt % calcium stearate.
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The polymeric material and any additives optionally are mixed with a
blowing agent and/or other cell-producing material. The blowing agent may be
added in liquid, powder, or pellet form. The temperature at which the blowing
agent releases gas may vary depending on the blowing agent selected.
Examples of blowing agents that may be suitable for use with the present
invention include, but are not limited to, azodicarbonamide (ADC), expandable
microspheres, OBSH (4-oxy bis benzene sulfonyl hydrazide), p-toluene
sulfonyl semicarbizide, sodium bicarbonate, citric acid, and the like, and any
combination thereof.
One particular example of an ADC blowing agent that may be suitable
for use with various aspects of the present invention is Blo-Foam PMA 50
pellets, commercially available from Rit-Chem Company, Inc. (Pleasantville,
New York). PMA 50 is heat-activated and includes about 50% azo blowing
agent (ADC 1200 grade) and 50% PVC. PMA 50 is therefore 50% active. The
average particle size (i.e., the average diameter of the particle) is from
about 3
to about 11 microns. The PMA 50 may be added in an amount of from about
0.1% to about 5% (wt/wt) based on the percent "active" azodicarbonamide. For
example, the PMA 50 may be added in an amount of from about 0.5 to about
2.0 wt % (about 0.25% to about 1.0% active) of the mixture. The
decomposition temperature of the active azo ingredient, ADC 1200, is
approximately 195 C to 220 C (383 F to 428 F). However, the effective
decomposition temperature of the activated azodicarbonamide of the pellet
ranges from about 175 C to 185 C (347 F to 365 F).
The gas volume resulting from decomposition of azodicarbonamide may
be from about 85 to about 115 ml/gram of azodicarbonamide. When the
blowing agent is heated to its activation temperature, it decomposes and
produces various gases including, for example, nitrogen, carbon monoxide,
carbon dioxide, and ammonia. These gases expand and produce cells or gas
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pockets in the material. When the material hardens or cures, permanent
bubbles, cavities, or voids are established.
While the use of azo blowing agents is described in detail herein, it will
be understood that other blowing agents having decomposition temperatures as
low as about 163 C (325 F) may be used as long as the temperature during
processing can be kept below the decomposition temperature.
The activation or decomposition. rate of any of the various blowing
agents can be altered through the use of an activator. Suitable activators for
azodicarbonamide blowing agents include, but are not limited to, transition
metal salts, particularly those of lead, cadmium, and zinc or organometallic
compounds, such as zinc stearate and barium stearate. Although dependent on
the composition and activation characteristics of the blowing agent,
activators
typically are added at approximately a 1 to 1 ratio of activator to blowing
agent.
If desired, one or more cell-producing materials may be added to the
mixture in addition to, or as a substitute for, a chemical blowing agent. For
example, expandable hollow microspheres, such as those produced by
Expancel, Inc., may be added to the polymeric material. These microspheres
are formed as spherical polymer shells encapsulating a gas. When heated, the
shell softens and the gas pressure inside the shell increases. As a result,
the
microsphere expands. When dispersed in an uncured backing layer, the effect
of the expandable microspheres is similar to that of a blowing agent. When the
backing layer is heated, the microspheres expand creating cells or voids in
the
polymeric material. These cells or voids are established permanently as the
backing layer material is cured or hardens.
Where a non-foam backing is used, a blowing agent is not needed in the
composition. Additionally, more filler may be used if desired, for example,
from about 50 to about 60 wt %. Thus, according to one aspect of the present
invention, the backing formulation may comprise from about 35 to about 99 wt
% PVB (including virgin and/or waste PVB material), about 0 to about 70 wt %
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filler, and from 0 to about 5 wt % processing aid. According to another aspect
of the present invention, the backing formulation may comprise from about 40
to about 65 wt % PVB from about 40 to about 65 wt % filler, and from 0 to
about 1 wt % release aid, such as calcium stearate. According to yet another
aspect of the present invention, the backing formulation may comprise from
about 30 to about 40 wt % PVB, from about 11 to about 17 wt % plasticizer,
from about 45 to about 55 wt % calcium carbonate filler, and from about 0.5 to
about 1.0 wt % calcium stearate. In one particular aspect, the backing
formulation may comprise about 34.7 wt % PVB, about 14.9 wt % plasticizer,
about 49.5 wt % calcium carbonate filler, and about 0.9 wt % calcium stearate.
The polymeric materials and the optional blowing agent and/or cell-
producing materials then are heated to melt and blend the components. In one
aspect, the components include recycled and/or virgin PVB, calcium carbonate
filler, blowing agent concentrate (a masterbatch of azodicarbonamide and
polyolefin), and a calcium stearate calender release aid. The blending may be
accomplished through the use of any suitable batch mixer (e.g., a Banbury
mixer), extruder, FCM (Farrell Continuous Mixer), or other mixing device.
In the exemplary process illustrated in FIG. 3, an extruder 50 is used to .
produce a molten blend of the various components. Examples of extruders that
may be suitable are Model 2DS-K 57M32 and ZSK-170 M 175010G, both
commercially available from Werner & Pfleiderer (Germany). A metal
scavenging station, such as a magnet (not shown), may be located at the
entrance of the feeder 55. A controller 53 is provided to ensure that the
extruder 50 and feeder 55 act cooperatively to maintain a constant feed
condition throughout the conveying zone to one or more kneading zones. The
materials pass through an extruder barrel 57 having a degassing or a vacuum
zone including at least one vent to assist with the removal of volatile
compounds, including water and VOC's. Additional vents are provided
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throughout the extruder to continue to remove volatile compounds from the
extrudate.
The materials then are passed through a pumping zone, which forces the
materials through a die 58. The pumping zone is used to develop sufficient
throughput without creating undesirable back pressure and torque in the
preceding zones or on the thrust bearings of the extruder 50.
The extruder 50 is operated at a temperature high enough to melt the
non-fibrous thermoplastic polymer materials in the material mixture and
produce a uniform, blended extrudate 59. However, if a blowing agent is
included in the material mixture, the temperature in the extruder 50 generally
is
kept below the decomposition temperature of the blowing agent to ensure that
the blowing agent is not activated during extrusion. For example, when an
azodicarbonamide blowing agent is used, the extruder 50 generally is operated
to achieve a melt temperature of from about 200 F to about 380 F as the
extrudate 59 exits the die 58. Thus, for example, the temperature at the die
head may be about 325 F.
Upon exit from the die 58, the blended extrudate 59 may be passed
through a metal detector 60 and fed into a calendering unit 80, which forms
the
blended material of the extrudate into a uniform sheet or rope. The dimensions
of the extrudate 59 may be established to provide ease of handling and feeding
of the calendering unit 80. In an illustrative embodiment, the extrudate 59
has a
substantially circular cross-section with a diameter of about 1 to about 5
in., for
example about 2 in. The material is calendered at a temperature of from about
190 F to 350 F, for example, at about 325 F, and maintained at the elevated
temperature until the material exits the calender, thereby further removing
VOCs.
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Where a non-foamed backing is used, and therefore no blowing agent is
included in the composition, the extruder may be operated at a higher
temperature as needed or desired to drive off additional VOC's.
A variety of calender types may be used in the methods disclosed herein.
As shown in FIG. 4, a standard three cylinder inverted J-stack calender 70 may
be used. The extrudate 59 is fed to a first nip 74 between first and second
counter-rotating heated rolls 71, 72. The extruder 50 provides a continuous
feed of material to the calender 70 to maintain a constant reservoir or bank
of
material 60 at the first nip 74. An intermediate sheet 61 is formed as the
material passes through the gap between the first and second rolls 71, 72.
The first and second rolls 71, 72 are rotated at different speeds so the
bank 60 of blended material ahead of the first nip 74 is rolled constantly and
kneaded in the direction of the rotating rolls 71, 72. In an illustrative
example
where the rolls of the calender have a diameter of about 24 inches, the second
roll 72 may operate at about 5 rpm while the first roll 71 operates at about
4.5
rpm.
The intermediate sheet 61 is passed to a second nip 75 formed between
the second roll 72 and a third heated roll 73. The third roll 73 operates at a
faster speed than the second roll 72. In the illustrative example where the
second roll 72 operates at about 5 rpm, the third roll 73 may operate at about
6
rpm. A second bank of material 62 collects ahead of the second nip 75 and,
like the first bank 60, is rolled constantly in the direction of the rotating
rolls.
Shear and friction in the second bank 62 and the drawing of the intermediate
sheet 61 between the second and third rolls 72, 73 tend to align any fibrous
materials present. The intermediate sheet 61 is thinned and widened as it
passes through the second nip 75 to form a final calendered sheet 63.
Optionally, the sheet 63 is passed between a pair of press rolls 76, where
it is pressed with a sheet of reinforcing material 82 supplied from a
reinforcing
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material roll 83 to form a reinforced sheet 65. The reinforcing material 82
can
be an open weave scrim material that retains its strength at the temperatures
used to activate the blowing agent. Suitable materials include woven polyester
and glass scrim. Non-woven or tissue type materials also may be used, but such
materials may necessitate the use of an additional adhesive layer when the
fmal
backing layer is bonded to the carpet back.
As shown in FIGS. 5A and 5B, the reinforcing material 82 may be
embedded substantially within the calendered sheet 63, although a portion of
the reinforcing material 82 may be exposed or even extend above the surface
64. The embedded reinforcing material 82 helps to provide dimensional
stability to the reinforced sheet 65 and prevent the buildup of residual
stresses
in the material that can cause non-uniform expansion when the void-producing
material is activated.
An alternate calendering process is illustrated in FIG. 6. The
calendering unit 180 uses a calender 170 having first, second, and third rolls
171, 172, 173 to process the blended extrudate 59. Each roll rotates at a
different speed. The calendering unit 180 is configured so that the
reinforcing
material 82, where used, is drawn through a nip 175 between the second and
third rolls 172, 173 along with the intermediate sheet 61. The reinforcing
materia182 may be fed into the nip 175 so that it passes between the surface
of
the third roll 173 and the material bank 62 that is maintained ahead of the
nip
175. The output is a reinforced calendered sheet 165 in which the reinforcing
material 82 is embedded at least partially in the polymeric material. The
optionally reinforced calendered sheet 165 then is passed to an oven 90 (FIG.
3) to produce the foam backing 310 (FIG. 8).
Yet another alternate calendering process is depicted in FIG. 7. The
calender unit 580 includes a calender 570 having four heated rolls 571, 572,
573, 574. The extrudate 59 is fed to the calender 570 at a first nip 575
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the first and second counter-rotating heated rolls 571, 572 and at a second
nip
576 between the third and fourth counter-rotating heated rolls 573, 574. The
first and fourth rolls 571, 574 rotate at a first speed and the second and
third
rolls 572, 573 rotate at a second speed greater than the first speed. A first
bank
of materia1560 is maintained at the first nip 575 and a second bank of
material
562 is maintained at the second nip 576. The first and fourth rolls 571, 574
are
rotated at different speeds from the second and third rolls 572, 573 so that
the
banks 560, 562 of blended material are rolled constantly and kneaded in the
machine direction. A first intermediate sheet 561 is formed as the material
passes through the gap between the first and second rolls 571, 572 and a
second
intermediate sheet 563 is formed as the material passes through the gap
between the third and fourth rolls 573, 574.
The first and second intermediate sheets 561, 563 are pressed together
by passing them both through a third nip 577 between the second and third
rolls
572, 573. A reinforcing material 82 is fed continuously from a supply roll 83
to
the third nip 577 between the first and second intermediate sheets 561, 563.
The result is a reinforced calendered sheet 565 in which the reinforcing
material is embedded substantially or completely. The calendered sheet 565
then can be cooled and rolled or passed to an oven where it is expanded to
form
reinforced foam backing.
In this aspect, because the calender 570 is fed continuously to two
places, additional changes to the processing line may be required. These may
include configuring the line to divide the extrudate 59 before delivery to the
calender 570 or providing two separate extruders 50. It will be understood
that
using multiple extruders would reduce the required throughput of each extruder
50 since the total amount of extruded material required for the foam backing
510 would be about the same as for the other foam backing embodiments. It
also will be understood that the composition in each extruder may be the same
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or may differ. Thus, for example, a first extruder composition may include a
particular polymer(s) and/or additive(s), and the second extruder may include
the same or different polymer(s) and/or additive(s). In doing so, the
properties
of the backing can be adjusted or enhanced for a particular product
application.
It also will be understood that the reinforcing material may be positioned in
any
manner throughout the thickness of the backing. Thus, for example, the
reinforcing material may be proximal one side of the backing or the other, or
may be positioned equidistant or substantially equidistant from both sides, as
desired.
As an alternative to calendering, the sheet of polymeric material may be
formed using a sheet, slot, or film die attachment in combination with the
extruder or may be formed using a second extruder with a sheet die. If a
second
extruder is used, the operating temperature of the second extruder also is
kept
below the decomposition temperature of the blowing agent.
Returning to FIG. 3, the reinforced sheet 65 optionally may be cooled at
a cooling station and formed into rolls, which then can be transferred to
another
processing line or stored.
Alternatively, according to one aspect of the present invention, the
unexpanded reinforced sheet 65 is transported from the calendering unit 80 to
an oven 90, where the reinforced sheet 65 is heated. If a chemical blowing
agent is used, the sheet 65 is heated to a temperature above the decomposition
temperature of the blowing agent. The reinforced sheet 65 may be supported
on and transported through the oven 90 by a conveyer 91. The reinforced sheet
65 may be passed through the oven 90 with the reinforcing material 82 facing
away from or towards the conveyer 90.
The oven 90 generally is configured to assure uniform heating and
airflow over the entire reinforced sheet 65. The oven temperature typically is
from about 300 F to about 450 F, for example, about 420 F. The airflow in the
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oven is maintained at a level sufficient to draw VOC's from the sheet. As the
temperature in the reinforced sheet 65 exceeds the decomposition temperature
of the blowing agent, gas pockets are formed that reduce the density and
increase the thickness of the reinforced sheet 65, thereby producing a
reinforced
foam backing 66. Using a blowing agent level of approximately 1.5% (0.75%
active) by weight of the backing formulation, the foam backing 66 can reach a
post-activation thickness that is 2 to 4 times the thickness of the unexpanded
sheet 65. In a typical carpet backing, this corresponds to a density reduction
from approximately 85 lbs/ft3 at 50 mils thickness to approximately 271bs/ft3
at
150 mils thickness. Similar expansion may be accomplished using expandable
microspheres. The reinforced foam backing may have a thickness of from
about 75 to about 200 mils. In another aspect, the backing may have a
thickness of from about 80 to about 160 mils. In yet another aspect, the
backing may have a thickness of from about 90 to about 100 mils.
Where a non-foamed backing is used, the oven may be maintained at a
temperature of from about 275 F to about 375 F, for example, about.300 F to
remove VOC's.
After exiting the oven 90, the reinforced backing 66 may be cooled and
accumulated into rolls at an accumulation station 92. The rolls may be stored
for later processing. Alternatively, the rolls of backing 66 may be used as a
separate pad or cushion for placement underneath carpeting. Alternatively
still,
the rolls may be passed directly to a finishing station (not shown) where the
backing is adhered to a pre-finished carpet product. The pre-finished carpet
may be formed according to numerous processes. In one exemplary process,
nylon yarns are tufted into a primary backing, thereby forming a textile
fabric.
A polyurethane dispersion pre-coat then is applied to the backside of this
fabric
to lock in the stitches and to create a surface to bond to the foamed backing.
The precoated carpet then is dried in an oven to remove the water in the
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polyurethane dispersion and form the precoat into a film. The resulting carpet
roll stock is wound into a roll for later processing by the finishing station
(not
shown).
The carpet roll stock and backing are aligned and subjected to heat, for
example, infrared heat, to cause the materials to adhere together. The
materials
may be pressed together and compacted using nip rollers. The heat may be
infrared heat or any other suitable source of heat maintained at a temperature
of
from about 900 F to about 1000 F, for example 950 F. This elevated
temperature further removes VOC's from the backing.
In one aspect, the resulting floor covering has a total volatile organic
compound emission factor of less than about 1 mg/m2/hr as measured according
to ASTM D-5116-1990. In another aspect, the floor covering has a total
volatile organic compound emission factor of less than about 0.75 mg/m2/hr as
measured according to ASTM D-5116-1990. In yet another aspect, the floor
covering has a total volatile organic compound emission factor of less than
about 0.5 mg/m2/hr as measured according to ASTM D-5116-1990. In still
another aspect, the floor covering has a total volatile organic compound
emission factor of less than about 0.375 mg/m2/hr as measured according to
ASTM D-5116-1990.
Optionally, an adhesive is applied to the back of the backing, opposite
the pre-fmished carpet. In one aspect, the adhesive is an acrylic polymer. The
adhesive may be applied in any of numerous manners and, in some instances, is
applied using a roll coater. The adhesive on the carpet then is dried to form
a
tacky surface. Any additional VOC's are removed further by heating in the
oven. A release liner is applied over the adhesive and the carpet is cooled
and
rolled up for shipment. If no adhesive is to be applied, the finished carpet
is
ready for shipment.
FIG. 8 illustrates a floor covering product 300 having a reinforced foam
backing 310 produced using the exemplary process described above. The floor
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covering product 300 comprises a tufted carpet 301 having looped pile yams
302 tufted or looped through a primary backing 304 and extending upwardly
therefrom. A polymeric pre-coat or backcoating 306 is used to fix the pile
yams 302 in place in the primary backing 304. The reinforced foam backing
310 includes a foam layer 311 comprising a plurality of substantially
uniformly
distributed closed cells 312. A partially or entirely open cell foam backing
also
may be used. The reinforced foam backing 310 also includes a reinforcing
layer or materia182 at least partially embedded in the upper surface of the
foam
layer 311. The reinforcing material 310 may be any material as described
above.
Another floor covering having a reinforced foam backing layer is shown
in FIG. 9. The floor covering 400 comprises a tufted carpet 401 having looped
pile yams 402 tufted or looped through a primary backing 404 and extending
upwardly therefrom. A polymeric pre-coat or backcoating 406 is used to secure
the pile yams 402 to the primary backing 404. The reinforced foam backing
410 includes a foam layer 411 comprising a plurality of substantially
uniformly
distributed closed cells 412. A substantially or entirely open cell foam
backing
also may be used. The foam layer 411 may comprise any suitable material or
combination of materials as described above.
The reinforced foam backing 410 also may comprise a reinforcing
material 82 adhered to the upper surface of the foam layer 411 using an
adhesive layer 414. The reinforcing materia182 can be an open weave fabric or
scrim formed from woven polyester or glass fibers, or any other material as
described above. The adhesive generally is selected for its ability to retain
structural integrity and adherence to both the reinforcing material and the
calendered sheet when subjected to the temperatures needed to activate the
blowing agent. The adhesive generally is compatible with both the backing
polymers and the pre-coat polymer to provide a suitable bond. In one aspect,
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the adhesive is RS-3120, commercially available from Solutia Inc.
(Springfield,
MA). The adhesive may be applied in an amount of, for example, from about 1
to about 5 ounces per square yard on a dry/dry basis. .
The reinforced foam backing 410 may be manufactured using the
process associated with the processing line shown in FIG. 3 but with the
additional step of applying the adhesive layer 414 to the calendered sheet 63
prior to application of the reinforcing material 82. This method may be used
if
the calendered sheet 63 has been cooled and is no longer soft enough to embed
the reinforcing material into the surface of the sheet. The combined adhesive
layer 414 and reinforcing material 82 serve to maintain the dimensional
stability of the reinforced calendered sheet through the expansion process to
produce a substantially uniform reinforced foam backing 410. The adhesive
used to attach the reinforcing material 82 also may be used to adhere the
reinforced foam backing 410 to the pre-coat 406 using the heat lamination
process discussed above. Alternatively, an additional adhesive may be used.
Yet another exemplary floor covering is illustrated in FIG. 10. The
floor covering 500 comprises a tufted carpet 501 having looped pile yarns 502
tufted or looped through a primary backing 504 and extending upwardly
therefrom. A polymeric pre-coat or backcoating 506 is used to secure the pile
yams 502 to the primary backing 504. The reinforced foam backing 510
includes a foam layer 511 comprising a plurality of substantially uniformly
distributed closed cells 512. A substantially or entirely open cell foam
backing
also may be used. The foam layer 511 may comprise the previously discussed
scrap materials such as the previously described waste polymeric carpet or
automotive windshield interlayer materials. These materials may include
fibrous aliphatic polyamide polymer materials that are in at least partial
alignment. The reinforced foam backing 510 may comprise a reinforcing
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material 82 entirely embedded within the foam layer 511. The reinforcing
material 82 may be any suitable material, as described above.
It will be understood that any of the various reinforced foam backings
formed in accordance with the present invention also may be applied to a
woven floor covering of the type depicted in FIG. 2. Both the tufted floor
covering and a similarly backed woven floor covering may be produced as roll
goods or may be used to produce carpet tiles. In either case, a pressure
sensitive adhesive layer and, if desired, a release cover may be applied to
the
underside of the reinforced foam backing.
According to another aspect of the present invention, a floor covering
backing including other waste polymeric materials is provided. A process for
forming such a backing is depicted in FIG. 11. Some of the waste polymeric
material may include thermoplastic materials generated during the manufacture
and/or disposal of various floor coverings. Virgin and/or recycled PVB also
may be included. Such material may be processed as follows, or may be
delivered directly to the extruder as described above.
Other thermoplastic materials that may be present include aliphatic
polyamides and/or other fibrous materials, polyolefins (e.g., polyethylene and
polypropylene), polymers based on vinyl monomers (e.g., vinyl esters, such as
vinyl acetate, and vinyl acetals), polymers based on acrylic monomers (e.g.,
acrylic acid, methyl acrylic acid, esters of these acids, and acrylonitrile),
other
thermoplastic polymers, and blends and copolymers thereof. Other materials
that are typically present in the scrap material include any of various
plasticizers, inorganic fillers, inorganic flame retardants, organic flame
retardants, fiberglass, blowing agents, polyester, pigments, stabilizers, oils
and
processing aids and antisoiling or antistaining chemicals.
The fibrous materials that may be present in the material in an amount of
from 0 to about 40 wt % of the total amount of material, for example, about 12
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wt % of the total amount of material. The fibrous materials are believed to
add
strength and stability to the fmal recycled backing product.
The waste polymeric material may include aliphatic polyamide
polymers. As used herein, the term "aliphatic polyamide polymer" refers to,
but is not limited to, any long-chain polymeric or copolymeric amide that has
recurring amide groups as an integral part of the main polymer or copolymer
chain, which may be in the form of a fiber. Examples of aliphatic polyamides
can include wool, nylon 6 or poly (omega-caprolactam); nylon 66 or poly
(hexamethylenedia mine-adipic acid) amide; poly (hexamethylenediamine-
sebacic acid) amide or nylon 610; and the like. When present in fibrous form
in
the final manufactured product, alignment of the aliphatic polyamide polymers
in the product material may add to the strength of the material, particularly
the
tear strength of the material lateral to the direction of fiber alignment.
It will be understood that the waste polymeric material may be provided
as a pellet, chip, tiles, sheet, strips, or in any other form. In some
instances, it
may be necessary or advantageous to subject the polymeric material to one or
more processes that further reduce the size of the waste material. In other
instances, the waste polymeric material may be suitable for direct feeding
into
the extruder.
Viewing FIG. 11, waste polymeric material ("scrap") 15 is delivered to
a guillotine chopper 20. The guillotine chopper 20 may be any conventional
guillotine chopper that coarsely chops the waste polymer material into 3/4 to
1
inch in width portions. One example of a suitable guillotine chopper is Model
CT-60 available from Pieret, Inc. The chopped mixture 15A is transported, for
example, via conveyer belts 25 and 26 to a granulator 40, which grinds the one
inch portions into fragments at least an order of magnitude smaller than the
original size of waste polymeric material. Typically, this may be less than
about 3/8 in. in width. One example of a suitable granulator is Model 24-1
available from Cumberland Company.
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The granulated material 15B is typically in the form of a fluffy, fibrous
material and solid polymeric particles. The granulated mixture 15B may be
transported to a densifier or plastcompactor 41, which forms the granulated
mixture into a densified material 42. The densifier 41 can be designed to
heat,
melt, and form or compact the granulated mixture 15B into semi-uniform
pellets. These pellets increase the throughput of the extruder 50 and allow
the
extruder 50 to produce a more uniform blend of molten recycled material. One
exemplary densifier that may be suitable for use with the present invention is
a
Plastcompactor Pelletizer Model No. CV50, commercially available from
HERBOLD ZERKL,EINERUNGSTECHNIK GmbH, has an approximate
volume densification ratio of 2:1 (original granulated material to densified
material volume). The use of the densifier 41 can increase the output of the
extruder 50 from approximately 1,000 lbs per hour to approximately 4,000 to
6,000 lbs per hour.
Optionally, if a finer material is required, the densified, pelletized
material 42 is sent via a conveyor to a cryogenic grinder (not shown) that
uses
liquid nitrogen to freeze and pulverize the densified, pelletized material to
form
a hard cryogenically ground material that is fed into the extruder 50. The
cryoground material may be made up of particles having a diameter of from
about 0.01 to about 0.20 in. These particles may be screened to remove
particles larger than a desired limit. Cryogenic grinding also may be used as
an
alternative to or as a precedent step to the densification of the granulated
material 15B. In such instances, the granulated mixture 15B can be sent via a
conveyor 26 to a cryogenic grinder (not shown). , The cryogenically ground
material then may be sent either to the densifier 41 or directly to the
extruder
50.
The densified material and/or cryogenically ground material 42 may be
transported via air in a conduit 43 to a Gaylord loading station 45 and/or to
a
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silo 46. If desired, fines, dust and/or fibers may be removed and separated
from
the densified material and/or cryogenically ground material 42 using an
elutriation process or other suitable process. The densified material and/or
cryogenically ground material 42 then is conveyed to the extruder feeder 55
which feeds the extruder 50. Additional recycled material, such as granulated
waste thermoplastics, may be added to the waste polymeric material 42 in the
hopper. Virgin material also may be added.
The process continues in a manner similar to that discussed in
connection with FIG. 3. It will be understood that various other processing
times, temperatures, line speeds, and other conditions may vary depending on
the composition of the polymeric materials used to form the floor covering
backing and the quantity of VOC's to be removed. Thus, while certain
processing conditions are described herein, other conditions are contemplated
hereby.
Still viewing FIG. 11, after exiting the oven 90, the foam backing 667
may be cooled and accumulated into rolls at an accumulation station 92. The
rolls of reinforced foam backing 667 then may be stored or transported to a
carpet finishing line where the backing is adhered to a carpet product. In
this
and other aspects, the reinforced foam backing 667 also may be used as a
separate pad or cushion for placement underneath carpeting.
Alternatively, after cooling, the reinforced foam backing 667 may be
passed directly to a finishing station (not shown) where it is adhered to the
carpet product. To bond the reinforced foam backing to a pre-finished carpet
having a polymeric pre-coat layer, heat may be applied to the reinforced side
of
the reinforced foam backing and to the pre-coat layer of the carpet. The
reinforced side of the reinforced foam backing then is contacted with the pre-
coat layer and the two layers are pressed together.
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In one aspect, the resulting floor covering has a total volatile organic
compound emission factor of less than about 1 mg/m2/hr as measured according
to ASTM D-5116-1990. In another aspect, the floor covering has a total
volatile organic compound emission factor of less than about 0.75 mg/m2/hr as
measured according to ASTM D-5116-1990. In yet another aspect, the floor
covering has a total volatile organic compound emission factor of less than
about 0.5 mg/m2/hr as measured according to ASTM D-5116-1990. In still
another aspect, the floor covering has a total volatile organic compound
emission factor of less than about 0.375 mg/m2/hr as measured according to
ASTM D-5116-1990.
FIG. 12 illustrates an exemplary floor covering product 600 having a
reinforced foam backing 667 formed from according to the exemplary process
described above. The floor covering product 600 comprises a tufted carpet 601
having looped pile yarns 602 tufted or looped through a primary backing 604
and extending upwardly therefrom. A polymeric pre-coat or backcoating 606 is
used to fix the pile yarns 602 in place in the primary backing 604. The
reinforced foam backing 667 includes a foam layer 611 that may comprise one
or more of the previously discussed scrap materials, such as waste polymeric
carpet materials or waste safety glass interlayer. The foam layer also
comprises
a plurality of substantially uniformly distributed closed cells 612. However,
it
will be understood that a foam layer comprising open cells also may be used.
The foam layer 611 optionally includes fibrous materials 614 that have
retained their fibrous form. The fibers 614 remain, at least to some degree,
aligned in a direction corresponding to the machine direction 616, despite the
presence of the cells 612.
It will be understood that the backing layer 667 also may be used with a
woven floor covering of the type depicted in FIGS. 2, 8, and 9. Both the
tufted
floor covering and a similarly backed woven floor covering may be produced as
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roll goods or may be used to produce carpet tiles. In either case, a pressure
self-release adhesive layer may be applied to the underside of the reinforced
foam backing. If an adhesive layer is applied, a release liner may be applied
over the adhesive.
EXAIVIPLES
PVB chips and various carpet samples having a PVB backing were
evaluated to determine the level of VOC's present. The PVB chip (Sample 1)
was obtained from Dlubak Glass Company. A description the various carpet
samples (Samples 2-5) is provided in Table 1.
Table 1.
Sample 2 Sample 3 Sample 4 Sample 5
Carpet face style name Kente Unknown Calypso Luminaire
Gauge 1/12 Unknown 1/12 1/10
Pile Height Average (in.) 0.187 Unknown 0.187 0.187
(ASTM D-148, sect. 12)
Fiber system 100% Unknown TDX Antron
DuPont nylon Lumena-
Lumena- Reg.
Reg. Nylon Sol.dyed
6,6 nylon 6,6
Pile Units per inch 8.0 Unknown 6.9 11.0
(ASTM D-148, sect. 12)
Nylon basis wt (osy) 20.0 Unknown 22.0 26
Primary backing basis wt 3.2 3.2 3.2 3.2
Polymer pre-coat Dow 605.01 PUD compounded with additives
Pre-coat basis wt (dry) 22 22 22 22
(osy)
Backing basis wt (osy) 43.4 43.4 43.4 43.4
Total basis wt (osy) 88.6 Unknown 90.6 94.6
Samples 1-3 and 5 were evaluated according to ASTM D-5116-1990.
Sample 4 was evaluated according to California 01350 guidelines. Thus, some
data is not available, as indicated by "NA". The results are provided in Table
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2. A value indicated as "BDL" was beyond the detection limit for the
compound. "NT" means that the sample was not tested for the particular
compound. All values are measured in g/m2/h. It should be noted that the
amount of PVB in Sample 1 was about 10 times greater than the amount of
PVB in Samples 2-5.
Table 2.
CRI Sample Sample Sample Sample Sample
Compound Limit 1 2 3 4 5
Acetaldehyde 20 BDL NT NT Pass Pass
Benzene 55 BDL BDL BDL Pass Pass
Caprolactam 120 BDL BDL BDL Pass Pass
2-Ethylhexanoic
acid 46 157.0 2.9 BDL Pass Pass
Formaldehyde 50 BDL NT NT Pass NT
1-Methyl-2-
pyrrolidinone 300 BDL 96.4 BDL Pass Pass
Naphthalene 20 BDL BDL BDL Pass Pass
Nonanal 24 BDL BDL BDL Pass Pass
Octanal 24 BDL BDL BDL Pass Pass
4-
Phenylcyclohexene 50 BDL NT NT Pass NT
Styrene 410 BDL BDL BDL Pass Pass
Toluene 280 BDL 1.2 BDL Pass Pass
Vinyl acetate 400 BDL BDL BDL Pass Pass
Other VOCs 4377.7 41.7 446.6 NA <500
Total VOC 500 4534.7 142.2 446.6 NA Pass
Total VOC from
PVB chip 4534.7 39.8 255.6 NA NT
Total VOC from
carpet components
other than PVB
chip 0.0 102.4 191.0 NA NT
Total 4534.7 142.2 446.6 NA <500
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Accordingly, it will be readily understood by those persons skilled in the
art that, in view of the above detailed description of the invention, the
present
invention is susceptible of broad utility and application. Many adaptations of
the present invention other than those herein described, as well as many
variations, modifications, and equivalent arrangements will be apparent from
or
reasonably suggested by the present invention and the above detailed
description thereof, without departing from the substance or scope of the
invention.
While the present invention is described herein in detail in relation to
specific aspects, it is to be understood that this detailed description is
only
illustrative and exemplary of the present invention and is made merely for
purposes of providing a full and enabling disclosure of the present invention.
The detailed description set forth herein is not intended nor is to be
construed to
limit the present invention or otherwise to exclude any such other
embodiments,
adaptations, variations, modifications, and equivalent arrangements of the
present invention, the present invention being limited solely by the claims
appended hereto and the equivalents thereof.
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