COLLES THIXOTROPIQUES FORMATRICES DE POLYURETHANE POUR DOSSIER DE TAPIS

THIXOTROPIC POLYURETHANE-FORMING ADHESIVES FOR CARPETING BACKING

Abrégé anglais

Abstract of the Disclosure
A carpet backing is formed by applying a thixo-
tropic polyurethane adhesive composition as either a
laminating adhesive, a precoat adhesive or a unitary backing
to the underside of the primary fabric of tufted carpet.
The thixotropic adhesive composition, comprising a liquid,
hydroxyl-terminated diene polymer, a low molecular weight
reinforcing polyol, an isocyanate, a filler, and a catalyst,
provides substantially complete bundle wrap of each fiber
tuft without penetration through the primary fabric backing
material to the top side or face of the carpet. The
thixotropic polyurethane adhesive composition is applied to
the underside of the primary fabric backing material in
measured quantity and cured by the application of heat with
or without a secondary fabric being applied prior to curing.

Revendications

The embodiment of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A thixotropic adhesive composition having an initial
Brookfield viscosity of between about 3,000 and about 100,000
centipoises, as determined using a Model RVT Brookfield device
operated at 5 rpm using a number 5 spindle, said viscosity being
measured before addition of catalyst to the composition, and a
thixotropic ratio based on the Brookfield viscosity at 1 rpm and
at 20 rpm of between 1.3:1 and 10:1, said composition comprising
liquid, hydroxyl-terminated diene polymer having a hydroxyl
content of between about 0.6 and about 0.9 milliequivalents per
gram and a viscosity at 30°C of between about 30 and about 300
poises; polyol having an equivalent weight of between about 50
and about 300 and an average functionality of between 2.0 and 2.5
present in an amount between about 1.5 and about 8 times the
equivalents of diene polymer; isocyanate having a functionality of
between 2 and 3 present in an amount to provide a NCO/OH equivalents
ratio of between 0.95:1 and 1.5:1; an inorganic filler present in
an amount between about 40 and about 800 parts per 100 parts by
weight of diene polymer; and catalyst for said composition
present in an amount between about 0.02 and about 4 parts per 100
parts by weight of diene polymer.
2. The thixotropic adhesive composition of claim 1 in
which polyol having an average equivalent weight between 500 and
2200 is also present in an amount between about 0.1 and 5 times
the equivalents of diene polymer.
3. The thixotropic adhesive composition of claim 1 in
which the diene polymer is a homopolymer having the general
formula:
<IMG>
where n equals 44 to 65.
29

4. The thixotropic adhesive composition of claim 1 in
which the diene polymer is a copolymer having the general
formula:
<IMG>
where X is the benzene moiety and n equals 57 to 65.
5. A thixotropic adhesive composition for carpets having
an initial Brookfield viscosity of between about 3,000 and about
100,000 centipoises, as determined using a Model RVT Brookfield
device operated at a 5 rpm using a number 5 spindle, said viscosity
being measured before addition of catalyst to the composition,
and a thixotropic ratio based on the viscosity at 1 rpm and at 20
rpm of between 1.3:1 and 10:1, said composition comprising:
diene polymer having an average between about
2.1 and about 2.5 of predominantly primary, terminal allylic
hydroxyls per molecule and being an addition polymer of 0 to 75
percent by weight of an alphamonoolefinically unsaturated monomer
of 2 to 12 carbon atoms, the balance consisting essentially of a
1,3-diene hydrocarbon of 4 to 12 carbon atoms, said polymer
having the majority of its unsaturation in the main hydrocarbon
chain and a number average molecular weight of 400 to 25,000;
low molecular weight polyol having an average
equivalent weight of between about 50 and about 300 and an
average functionality of between 2 and 2.5 percent present in
an amount between about 1.5 and about 8 times the equivalents of
diene polymer;
high molecular weight polyol having an average
equivalent weight of between 500 and 2200 present in an amount
up to 5 times the equivalents of diene polymer;
isocyanate having a functionality between 2 and
3 present in an amount which provides a NCO/OH equivalents ratio
of between 0.95:1 and 1.5:1;

an inorganic filler present in an amount
between about 40 and about 800 parts per 100 parts by weight
of diene polymer;
hydrocarbon oil having a viscosity at 100°F of
between 50 and 2500 Saybolt universal seconds present in an amount
up to 200 parts of oil per 100 parts by weight of diene polymer;
and
catalyst for said composition present in an
amount of between 0.02 and 4 parts per 100 parts by weight of
diene polymer.
6. The thixotropic adhesive composition of claim 5 which
further includes up to 10 parts of water per 100 parts by weight
of diene polymer.
7. The thixotropic adhesive composition of claim 5 in
which the isocyanate is present in an amount which provides a
NCO/OH equivalents ratio of between 1.1:1 and 1.2:1; the filler
is present in an amount between about 100 and about 600 parts
per 100 parts by weight of diene polymer; the hydrocarbon oil
is an aromatic hydrocarbon oil having a viscosity at 100°F of
between 150 and 1500 Saybolt universal seconds; and the catalyst
is present in an amount between about 0.1 and about 2.0 parts
per 100 parts by weight of diene polymer.
8. The thixotropic adhesive composition of claim 5 in
which the diene polymer is a butadiene homopolymer having an
equivalent weight of 1180; the low molecular weight polyol is
bisisopropanol aniline; the high molecular weight polyol is
polypropylene glycol; the hydrocarbon oil is naphthenic process
oil; the isocyanate is diphenyl methane 4,4' diisocyanate, the
filler is kaolin; and the catalyst is dibutyl tin dilaurate.
31

9. The thixotropic adhesive composition of claim 8
in which up to about 100 parts of calcium carbonate per hundred
parts by weight of diene polymer and between about 0.3 and about
8 parts of water per 100 parts by weight of diene polymer are
also present.
10. The thixotropic adhesive composition of claim 5 in
which the diene polymer is a butadiene styrene copolymer having
an equivalent weight of 1530, the low molecular weight polyol
is bisisopropanol aniline; the high molecular weight polyol is
polypropylene glycol; the hydrocarbon oil is naphthenic process
oil; the isocyanate is diphenyl methane 4,4' diisocyanate; the
filler is kaolin; and the catalyst is dibutyl tin dilaurate.
11. Carpet including a primary backing material, tufted
yarn stitched through the primary fabric backing to provide a
pile surface on one side of the primary backing and a loop of
yarn on the underside of the primary backing and a layer of
thixotropic adhesive composition adhered to the underside of the
primary backing and the loop of yarn, said thixotropic composi-
tion having an initial Brookfield viscosity of between about
3,000 and about 100,000 centipoises, as determined using a Model
RVT Brookfield device operated at 5 rpm using a number 5 spindle,
said viscosity being measured before addition of catalyst to the
composition, and a thixotropic ratio based on the viscosity at 1
rpm and at 20 rpm of between 1.3:1 and 10:1, said composition
comprising liquid, hydroxyl-terminated diene polymer having a
hydroxyl content of between about 0.6 and about 0.9 milliequivalents
per gram and a viscosity at 30°C of between about 30 and about
300 poises; high molecular weight polyol having an average
equivalent weight between about 500 and 2200 present in an amount
up to 5 times the equivalents of the diene polymer; low molecular
weight polyol having an equivalent weight of between about 50 and
32

about 300 and an average functionality of between 2.0 and 2.5
present in an amount between about 1.5 and about 8 times the
equivalents of diene polymer; isocyanate having a functionality
of between 2 and 3 present in an amount to provide a NCO/OH
equivalents ratio of between 0.95:1 and 1.5:1; an inorganic filler
present in an amount between about 40 and about 800 parts per
100 parts by weight of diene polymer; oil extending hydrocarbon
liquid present in an amount of up to 200 parts per 100 parts by
weight of diene polymer; water present in an amount up to 10 parts
per 100 parts by weight of diene polymer; and catalyst for said
composition present in an amount between about 0.02 and about 4
parts per 100 parts by weight of the diene polymer.
12. The process of producing carpeting which comprises
applying to the underside of a pile-faced primary fabric backing
material a thixotropic polyurethane composition having a thixo-
tropic ratio based on the viscosity, as determined using a Model
RVT Brookfield device operated at 1 rpm and at 20 rpm, of between
1.3 to 1 and 10 to 1, said composition comprising liquid, hydroxyl-
terminated diene polymer having a hydroxyl content of between about
0.6 and about 0.9 milliequivalents per gram and a viscosity at
30°C of between about 30 and 300 poises; high molecular weight
polyol having an average equivalent weight between about 500 and
2200 present in an amount up to 5 times the equivalents of the
diene polymer; low molecular weight polyol having an equivalent
weight of between about 50 and about 300 and an average functionality
of between 2.0 and 2.5 present in an amount between about 1.5
and about 8 times the equivalents of diene polymer; isocyanate
having a functionality of between 2 and 3 present in an amount to
provide a NCO/OH equivalents ratio of between 0.95:1 and 1.5:1; an
inorganic filler present in an amount between about 40 and about
800 parts per 100 parts by weight of diene polymer; oil extending
hydrocarbon liquid present in an amount of up to 200 parts per
100 parts by weight of diene polymer; water present in an amount
33

up to 10 parts per 100 parts by weight of diene polymer; and
catalyst for said composition present in an amount between
about 0.02 and about 4 parts per 100 parts by weight of the
diene polymer, said viscosity being measured before addition of
catalyst to the composition.
13. The process of claim 12 in which the composition is
applied to the underside of the primary fabric backing at an
application rate of between about 12 and about 37 ounces per
square yard.
14. The process of claim 12 which further includes the
step of applying another layer of material to the composition
prior to curing but after the composition has been spread over
the underside of the primary fabric backing material.
15. The process of claim 14 which comprises applying a
foam as the layer of material applied prior to curing.
34

Description

1063'~78
Field of the Invention
The present invention relates to thixotropic
adhesive compositions, their application to carpets, and to
the resulting carpet material. More particularly, the
present invention is directed to thixotropic polyurethane
adhesive compositions which can be advantageously applied
to carpets as a unitary backing, a precoat adhesive~ or a
laminating adhesive, the application of such compositions
and the resulting carpet material.
Background of the Invention
The tufting method which is now generally employed
for the manufacture of carpets comprises looping pile fibers
of natural or synthetic material through a relatively
inexpensive woven or non-woven textile base, known as the
primary fabric backing material. Short loops of the long
pile fibers are pushed through the primary fabric backing
material such that one single continuous length of fiber
constituting a complete row of pile in the carpet is formed.
me elongated loops extending from the base (the top side)
of the primary fabric backing material can remain connected
or severed, depending on whether a loop pile or a cut pile
carpet is desired. The loops on the bottom side of the
carpet are not cut. These pile loops or tufts are not
securely fastened in the tufting process. Without
additional anchorage these fibers or the tufts can be
pulled from the primary fabric or otherwise disarrayed.
Necessary anchorage is provided by applying an adhesive
material in liquid form to the underside of the carpet. The
adhesive applied to the underside of the carpet is
accordingly of major importance to the quality and
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performance of the carpet. It retains the pile fibers or
tufts in place, secures the individual fibers of the yarn,
prevents pilling o~ the yarn and controls dimensional
stability.
~ ithout additional backing material applied to the
adhesive material on the underside of the carpet, the carpet
is said to have a unitary backing. Carpets having a unitary
backing are used principally as commercial carpeting. If a
sponge like material (or foam) is applied after the adhesive
material is applied, the adhesive coating is referred to as
a precoat composition. Uncured foam material can be applied
directly to the precoated carpet back and cured in place, or
it can be cured as a separate sheet and then laminated to
the back of the carpet by means of the precoat or use of
another adhesive. m e precoat provides good tuft lock, while
the foam material, such as polyvinyl chloride or styrene
butadiene copolymer, serves as a cushion back for the carpet
For the standard double back carpet, the adhesive
layer is referred to as a laminating adhesive. After the
laminating adhesive is applied to the underside of the
primary fabric backing material of a double back carpet, a
further backing layer of secondary fabric material, known as
the scrim, is applied to the coated underside of the carpet.
m e scrim serves to improve dimensional stability,
appearance of the carpet and also to enhance tuft lock~ i.e.
the strength with which the fibers are retained in the
primary fabric backing. The laminating adhesive for double
back carpets serves not only to anchor the pile fibers or
tufts, but also to adhere the scrim to the carpet. Con-
ventionally, in the process of making double back tufted

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carpets the laminating adhesive is applied in liquid form tothe underside of the carpet and the scrim is applied to the
same side while the laminating adhesive is still wet and
uncured. The carpet is then passed through an oven to dry
and cure the laminating adhesive.
When reference is made herein to carpets, it will
be understood that any fabric like sheet material is
contemplated, whether tufted, woven, ~nitted, felted,
cemented or otherwise, and that the fabric can be a carpet,
rug, mat, floor covering, floor tile, wall covering or the
like. The primary fabric is normally a material such as
jute, burlap or polypropylene. The scrim or secondary fabric
can consist of natural and/or synthetic materials, such as
jute, hessian, burlap, nylon, polypropylene and the like.
The pile fibers can also be natural or synthetic materials,
such as wool, polyacrylate~ cellulose acetate, polyester,
nylon, polyacrylonitrile, polypropylene and the like, as
well as mixtures of such materials.
Styrene butadiene rubber latex or carboxylated
styrene butadiene rubber latex of the type commonly employed
as a laminating adhesive has several known disadvantages.
Such adhesive requires a long cure time at relatively high
temperatures (e.g., 300F. for 8 to 10 minutes) and this
means that large expensive curing ovens must be employed.
With certain heat sensitive fibers that require lower curing
temperatures, even longer curing times are necessary.
Carboxylated styrene-butadiene latex adhesive may have a
strong odor of ammonia associated with it and sometimes
finished carpets have a heavy and unpleasant odor o~ styrene.
In addition, carboxylated butadiene-styrene polymer adhesives

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can contain some residual unsaturation which tends to cause
unsatisfactory aging characteristics, resulting in a loss
of flexibility. In fact, polymerization which occurs as a
result of such residual unsaturation has caused the backing
of carpets and rugs to become stiff after only a few years.
Another disadvantage o~ carboxylated styrene butadiene
rubber latex adhesive is the required method of application.
In general a pan coater consisting of a latex pan, one or
two adjustable doctor or striker bars, one or two variable
speed coater rolls and one or two adjustable tension rolls
are required for the application of such adhesive. These
require a fairly high degree of operator skill and
attention to achieve a proper degree of penetration of
adhesive into tufts. It is important that the adhesive
employed for carpets not migrate past the primary backing
fabric to the face or top side of the carpet since this
migration can cause the yarn to become stiff and render the
final carpet unacceptable. If the settings are not correct
for the particular type of yarn used rejects become quite
high. Quality of the finished carpet thus becomes highly
dependent on operator skill and conscientiousness and
increased expenses are incurred from the fact that several
employees are required to operate the equipment. Another
disadvantage is the poor green strength of carboxylated
styrene butadiene rubber latex adhesive. If effective
adhesion does not occur until near the end of a curing
cycle the chances of delamination and product waste increase
greatly The advent of certain synthetic materials in the
carpet industry which permit a carpet to be used both
indoors and outdoors has given rise to further problems in

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connection with the preparation or the manufacture of
carpeting. Polypropylene is a relatively cheap material which
in most respects is quite satisfactory for use as the pile
fiber, the primary fabric backing material, and the scrim, or
the secondary fabric substrate, of a carpetO However, poly-
propylene presents an adhesion problem since latex compositions
normally employed in carpet manufacture do not adhere well to
the surface of polypropylene. Carpets prepared from poly-
propylene have been subject to delamination of the scrim or
secondary fabric substrate. In order to overcome this problem
attempts have been made to employ multiple intervening
adhesive layers, resulting in increased production costs.
Summary of the Invention
An object of the present invention is to provide
improved adhesive compositions which find particular applica-
tion for rug and carpet backing applications.
Another object of the present invention is to
provide a solvent-free polymer composition to avoid evapora-
tion of water and/or organic volatile materials into the
atmosphere while curing.
A further object of the present invention is to
provide improved thixotropic polyurethane adhesive compositions
which can be used as carpet backing adhesive.
Still a further object of the present invention is
to provide low coat adhesive compositions which have excellent
adhesion with respect to natural and synthetic materials and
good resistance to aging.
Yet another object o~ the present invention is to
provide thixotropic polyurethane compositions which can be
used as unitary backing, precoat adhesive or laminating

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adhesive for carpets.
Another object of the present inventio~ is to
provide improved procedures for applying carpet backing
adhesive compositions.
A still further object of the present invention
is to provide carpet material having good tuft lock and
bundle wrap.
The thixotropic adhesive compositions provided in
a~cordance with the present invention comprise a mixture o~
a liquid hydroxyl-terminated diene homopolymer or copolymer,
a low molecular weight polyol, an isocyanate, a filler, and
catalyst. These compositions have an initial Brookfield
viscosity of between about 3,000 and about 100,000
centipoises at 5 rpm using a number 5 spindle. More
especially, the adhesive compositions of the invention
comprise a mixture of a liquid hydroxyl-terminated diene
homopolymer or copolymer, a polyol having an equivalent
weight of between about 5Do and about 2200 present in an
amount up to 5 times the equivalents of diene polymer; a
polyol having an equivalent weight of between about 50 and
about 300 present in an amount between about 1.5 and about
8 times the equivalents of diene polymer, an isocyanate
material having a functionality of between 2 and 3 present
in an amount to provide a NCO/OH equi~alents ratio of
between 0.95:1 and 1.5:1; at least one filler present in an
amount between about 40 and about 800 parts per 100 parts
by weight of diene polymer; an oil extending hydrocarbon
liquid present in an amount up to 200 parts per 100 parts
by weight of the diene polymer; water present in an amount
up to 10 parts per 100 parts by weight o~ the diene polymer,

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and at least one catalyst capable of accelerating the cure
time of the composition, present in an amount between
about 0.02 and about 4 parts per hundred parts by weight
of the diene polymer. m e resulting composition has an
initial ~rookfield viscosity at 5 rpm using a number 5
spindle of between about 3,000 and about 100,000 and the
ratio of the viscosity at 1 rpm and 20 rpm ~or the
thixotropic composition is between about 1.3:1 and 10:1.
Conventional additives such as oxidation inhibitors, pot
li~e inhibitors, stabilizers, pigments and the like can
be incorporated in the adhesive compositions for improved
characteristics.
Description of the Preferred Embodiments
m e polymeric materials combined with isocyanate
to produce the urethane adhesive compositions of the
present invention are liquid, hydroxyl-terminated diene
homopolymers and copolymers. The polymers possess
predominantly primary, terminal hydroxyl groups of the
allylic type and have a hydroxyl content of between about
o.6 and about 0.9 milliequivalents per gram and a
viscosity at 30C. of between about 30 and about 300
poises. m e structure of the polymers accounts for their
high reactivity, especially with aromatic diisocyanates.
Oil extension, using low cost process oils, provides
formulation flexibility in controlling properties while
the liquid systems are uncured, such as viscosity pot life,
gel time and the like, as well as properties o~ the cured
product, including flexibility, cut growth, elongation
and the like.
Hydroxyl terminated homopolymers and copolymers

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contemplated for the present invention are disclosed in
more detail in U.S. Letters Patent Nos. 3,637,558,
3,674,743 and 3,714,110. These patents disclose polymers
which have an average of at least 2.1 and preferably between
about 2.1 and about 2.5 predominantly primary, terminal
allylic hydroxyls per molecular and being an addition polymer
of 0 to 75 percent by weight of an alpha-monoolefinically
unsaturated monomer of 2 to 12 carbon atoms, the balance
consisting essentially of a 1,3-diene hydrocarbon of about
4 to about 12 carbon atoms, said polymer having the majority
of its unsaturation in the main hydrocarbon chain and a
number average molecular weight of about 400 to about 25,000
as determined by cryoscopic, ebullioscopic and osmometric
methods.
As disclosed in the aforementioned patents, the
dienes which can be employed are unsubstituted, 2-substi-
tuted or 3,3-disubstituted 1,3-dienes of up to about 12
carbon atoms. The diene preferably has up to six carbon
atoms and the substituents in the 2- and/or 3-position can
be hydrogen, alkyl, generally lower alkyl, e.g., of one to
four carbon atoms, aryl (substituted or unsubstituted),
halogen, nitro, nitrole, etc. Typical dienes which can be
employed are 1,3-butadiene, isoprene, chloroprene, 2-cyano-
1,3-butadiene, isoprene, chloroprene, 2-cyano-1, 3-butadiene,
2,3-dimethyl-1,3-butadiene, etc.
Olefinically unsaturated monomers which can be
incorporated into the diene polymer products used in this
invention include alpha-mono olefinic materials of about
two or three to 10 or 12 carbon atoms such as styrene,
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vinyl ~oluene, methyl methacrylate, methylacrylate,
acrylic es~ers, vinyl chloride, vinylidene chloride, etc.
Acrylonitrile, acrylic acid, vinylidene cyanide, acrylamide,
etc., provide low-molecular weight hyd-oxy-terminated diene
intermediate copolymers which have sites suitable for
cross-linking. As can be seen, the usable olefinic
monomers can be ethylenes, substituted with halogen,
aromatic hydrocarbon, or even cyano or carboxyl-containing
radicals in some instances. The choice and amount of mono
olefinic monomer employed will often be determined on the
basis of properties desired. Generally the amount of
monoolefinic monomer in the polymer will be about 0-75
percent by weight of the total addition polymer, preferably
about 1 to 40 percent, or even about 10-40 percent.
Specific hydroxyl-terminated homopolymers
contemplated for the present invention are those having the
general formula:
HO~(CH2CH=CHCH2).2--(CH2C(CH=CH2)H) 2--(CH2cH=cHcH2) 63 OH
where n = 44 to 65. Specific examples include resin R-45M
having an equivalent weight of 1330 and a hydroxyl content
of 0.75 milliequivalents per gram; where n equals 44 to 60.
Another example is resin R-45HT having an equivalent weight
of 1180 and a hydroxyl content of o.85 milliequivalents per
gram where n equals 57 to 65.
Specific hydroxyl-terminated copolymers con-
templated for the present invention are those having the
general formula:
HOr (cH2cH=c~IcH2)a--(C(X)HC~2)b3nOH
~Jhere a = 0.75, b = 0.25, n = 57 to 65, and X is the
benzene moiety. An example of such a styrene-butadiene
*Trade Mark 10
,' ~ ,
! LS

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copolymer is re~in*CS-15 which has an equivalent weight of
1530, an iodine number of 335, and a hydroxyl content of
0.~5 milliequiv21ents per gram.
The lo~ molecular weight reinforcing polyols which
can be employed in the present invention in order to obtain
improved tensile strength, tear strength and adhesion are
those polyols having an equivalent weight of between about
50 and about 300 and preferably those which have an average
equivalent weight of between about 90 and about 2~0. The
contemplated polyols, which can be di, tri or tetra
functional, should have an average functionality of between
2.0 and 2.5. In general, these polyols are employed in an
amount between about 1.5 and about 8 times the equivalents
of liquid, hydroxy-terminated diene polymer utilized in
connection with the invention. Although bisisopropanol
aniline is a preferred polyol for the invention, other
polyols which can be used include bisisopropanol bisphenol A,
2-ethyl-1, 3-hexanediol, dipropylene glycol, diethyleneglycol
and bisisopropanol isophthalate.
Higher equivalent weight polyols, having an
equivalent weight of between about 500 and about 2200, can
also be included in an amount up to about 5 times the
equivalents of diene polymer, preferably between about 0.1
and about 5.0 times the equivalents of liquid, hydroxyl-
terminated diene polymer. For example, polypropylene
glycol can, if desired, be included in the polyurethane
compositions.
Isocyanates which can be employed to form the
polyurethane upon reaction with the liquid, hydroxyl-
terminated diene polymers include tolylene diisocyanate
*Trade Mark
- 11 -
tB

1063278
(TDI), diphenyl meth~ne 4,4'-diisocyanate (MDI) and
polymeric diisocyanates such as polyphenylmethane polyiso-
cyanate (PAPI). Other isocyanate materials which can be
used to produce urethane resin compositions of this
invention include any one of a number of materials containing
two or more isocyanate radicals, such as 1,5-naphthalene
diisocyanate, phenylene diisocyanates, trans-vinylene
diisocyanate, hexamethylene diisocyanate, octamethylene
diisocyanate, 3,3~-dimethoxy-4,4'-biphenyl diisocyanate, as
well as related aromatic and aliphatic isocyanates, which
can also be substituted with other organic or inorganic
groups that do not adversely affect the course of the
urethane forming reaction. The isocyanate material has a
functionality of between 2 and 3 and is used in an amount
to provide a NCO/OH equivalents ratio of between about
0.95:1 and about 1.5:1 and prefera~ly between about 1.0:1
and about 1.2:1.
A prepolymer can be employed as the isocyanate.
An isocyanate terminated prepolymer can be formed by adding
an excess of diisocyanate (e.g. tolylene diisocyanate) to
the hydroxyl-terminated diene homopolymer or copolymer.
Inorganic fillers are added in order to control
viscosity and prevent overpenetration into the carpet
fibers. Among the fillers which can be incorporated into
the adhesive compositions of this invention include
calcium carbonate, talc, clay, silica, zinc oxide, feldspar,
asbestos, carbon black and mixtures of these fillers. In
addition, fillers such a~ titanium dioxide, hydrated
alumina and barium sulfates can be employed. Generally,
the amount of filler utilized is between about 40 and about
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800 parts per 100 parts by weight of the liquid, hydroxyl-
terminated diene polymer and preferably the amount of
filler is between about 100 and about 600 parts per
hundred parts by weight of hydroxyl-terminated diene
polymer. The fact that high filler levels can be employed
means that a significant economic advantage can be obtained
using large amounts of inexpensive filler in the formula-
tion.
In order to keep the viscosity from becoming too
high with the filler loads utilized in connection with the
invention up to about 200 and preferably up to about 100
parts of a hydrocarbon oil per 100 parts by weight of
diene polymer are added. Preferably such hydrocarbon oil
is a naphthenic or aromatic oil which has a viscosity at
100F. of between about 50 and about 2500 Saybolt universal
seconds and preferably between about 150 and about 1500
Saybolt seconds. Because of odor characteristics,
naphthenic oils are the preferred materials. Paraffinic
oils can be used, but occasionally a compatibility problem
occurs with such oils. Since oil extension, which is
desirable for lowering costs and improving processibility,
sometimes tends to beharmful to certain physical properties,
including adhesion and tuft lock, higher molecular weight
extenders can be used to replace part or all of the oil
employed. Examples of such extenders include asphalt,
vulcanized vegetable oils, factice and lower molecular
weight polystyrene.
Catalysts employed in connection with
compositions of the present invention in order to provide
the necessary acceleration of cure time include triethylene

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diamine (DABC0), various tin, lead and ~inc containing
catalysts such as dibu~yl tin dilaurate, nickel acetyl
acetonate, ferric acetyl acetonate, stannous octoate,
cobalt naphthenate and the like as well as combinations of
such catalysts. The amount of catalyst employed depends
on the desired rate of cure at the curing temperature.
Generally, catalyst is used in an amount varying between
about 0.02 and about 4 parts per 100 parts by weight of the
liquid, hydr~xyl-terminated diene polymer and preferably
10 is employed in an amount between about 0.1 and about 2.0
parts per 100 parts by weight of the diene polymer.
Water can also be added to the compositions to
create a polyurethane foam or sponge. Specifically,
between 0 and about 10 parts o~ water per 100 parts by
weight of the liquid, hydroxyl terminated diene polymer can
be incorporated in the composition. Pre~erably, water is
incorporated between about 1.0 and about 8 parts per
hundred parts by weight of the diene polymer. Since the
isocyanate moiety is sensitive to water, the isocyanate
20 should be essentially isolated from water, air and the like
before reaction. In addition, the diene polymer and other
reactants, and particularly the fillers, which can contain
variable amounts of water, should be dried or degassed in
a vacuum to remove moisture before the reaction. The
preferred procedure is to remove all the moisture from the
ingredients and then incorporate the desired amount of
water into the reaction mixture. By following this
procedure it is possible to know precisely how much water
is in the composition, and it is accordingly possible to
30 obtain consistent results for each formulation.
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Generally when larger amounts of high molecular
weight polyol are used, amounts of the other ingredients
used are at the upper end of the ranges listed above.
Conversely, when low amounts of high molecular weight
polyol are used, amounts of the other ingredients are at
the lower end of the ranges listed above~ These various
amounts are adjusted to provide workable viscosities,
desirable cure times, and required fire retardancy, etc.
for each specific application.
Economically, it is often desirable to also
incorporate various inhibitors and other conventional
additives in the adhesive composition of the present
invention. For example, oxidation inhibitors can be
added to improve aging characteristics. Such inhibitors
include alkylated phenol and aromatic amines.
Other substances, which can be added to the
reaction mixture are pigments, plasticizers, surfactants,
stabilizers and the like. Surfactants, for instance,
can be added in order to increase the penetration of the
adhesive composition in the backing cloth or primary
fabric and around the pile so as to firmly bind the pile
to the backing cloth. Surfactants, such as various
silicone materials, serve to stabilize bubble formation.
In some instances small amounts of diluting agents, which
decrease the viscosity of the reaction mixture, can also
be added to increase penetration. Emulsifiers can be
incorporated to disperse limited soluble components.
Dispersing aids can be incorporated to prevent filler
settlement. In addition, dehydrating agents such as
molecular sieves or zeolite materials, e.g., ~inde 5A

1063Z78
molecular sieve, can be incorporated in order to regulate
water content. Preferably these materials are incorporated
in the polyol blend, as herinafter defined.
Generally, all ingredients except the isocyanate
are preblended. This is commonly called the polyol blend.
Conventional procedures can be employed for mixing or
blending the ingredients for the polyol blend, including
the use of double planetary arm mixers and Cowles high
speed mixers. The order of mixing can be varied to suit
the characteristics of the mixing equipment being used.
The powder material can be blended with a little liquid to
obtain a good dispersion and then the remainder of the
liquid is added or liquid can be blended and then the powder
material is incorporated. Mixing times will vary depending
on the efficiency of the mixing equipment and the type of
filler used. Thepowder material can be blended with a
little liquid to obtain a good dispersion and then the
remainder of the liquid is added or liquid can be blended
and then the powder material is incorporated. Mixing times
will vary depending on the efficiency of the mixing equip-
ment and the type of filler used.
As previously indicated the isocyanate moiety is
sensitive to water and accordingly in the preferred
practice moisture is initially removed from the reactants.
Alternatively, the reactants can be mixed and then degassed,
usually in a vacuum, to remove air bubbles and moisture
from the mixture. Following this procedure a mixture can
be degassed in a steam jacket kettle maintained under a
vacuum of 10 to 50 millimeters of mercury for a time period
which can be up to about 2 hours. Sometimes thin film
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1063278
evaporator type equipment is used to remove moisture.
m e viscosity o~ the resulting adhesive composi-
tion after the isocyanate is added to the polyol blend is
between about 3,000 and about 100,000 centipoises and
preferably between about 8,ooo and about 50,000 centipoises
as measured using a Brookfield viscosity device, Model RVT,
operated at 5 rpm (revolutions per minute) using a number
5 spindle. The viscosity measurement is made before
catalyst is added to the composition so as to eliminate the
effects of polymerization. The Brookfield viscometer and
its operation are described in "Development of Research
Technique for Evaluating the Low Temperature Fluidity of
Automatic Transmission ~luids" published by Coordinating
Research Council, Inc., February 1963, Appendix A. The
thixotropic ratio for the adhesive composition should be
high enough that filler does not settle out of the
composition and also high enough to prevent overpenetration
of the carpet while being low enough to enable the adhesive
composition to be pumped, readily blended, and easily
applied by doctoring procedures conventional in the art.
m e thixotropic ratio determined by viscosity measurements
made at 1 and at 20 revolutions per minute is between
about 1.3:1 and about 10:1 and preferably between about
2:1 and about 8:1 Among the thixotropic agents which can
be incorporated to achieve the desired viscosity and the
aforementioned ratio are clays, such as kaolinj asbestos;
amines; and silica.
To apply the reactive ingredients to the carpet,
the polyol blend and the isocyanate are preferably
accurately metered and mixed in a multi-component mix
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meter machine and continuously and immediately fed by
hose onto the underside of carpet (underside being up).
If desired, the catalyst, or water, or other components
(including fire retardant compound) can be fed into a
multi-component mi~ meter machine as separate accurately
metered streams. To assure better mixing a portion of
the extender oil can be incorporated with the isocyanate.
Usually the ingredients are applied at a temperature
between room temperature and about 150~. Preferably the
temperature of application is between about 80 and about
100F.
After the adhesive composition has been applied
to the underside of pile fiber or primary fabric substrate
the adhesive composition is then conventionally spread
with a doctor blade. As the mixture passes under the
blade, the shearing action of the blade reduces the
viscosity so that the mixture can be forced down into and
around the tufts of yarn. After passing under the blade,
the original high viscosity is regained preventing
undesirable overpenetration. The amount of adhesive
composition applied is normally just sufficient to obtain
adequate adhesion of the pile fibers to the primary
fabric substrate. Excess adhesive composition is not
only wasteful, but also can cause penetration of the
primary fabric, rendering yarn stiff and the final carpet
unacceptable. Typically, coating weights for carpets
vary from about 12 to about 37 ounces per square yard.
Preferably, however, the amount of adhesive composition
applied to the carpet ranges from about 20 to about 30
ounces per square yard. In effect the lower limit with
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respect to the amount applied is limited by the amount
necessary to adequately achieve the desired goal, whether
it be that of a laminating adhesive, precoat composition
or unitary backing.
Curing time and temperature can be varied.
Normally, curing is accomplished at a temperature in the
range between about 225 and about 350F. and preferably
in the range of from about 275 to about 325F. for a
period of about 0.3 to about 3 minutes. An oven or
heated drum can be used for curing.
Among the properties of a carpet which are
directly affected by the nature of the adhesive applied
are tuft lock, anti-fray properties, appearance and
dimensional stability. Whereas closely woven carpets
of high pile density may have adequate tuft lock
retention without application of an adhesive, tufted
carpets have virtually no tuft retention in the absence
of an adhesive. Anti-fray properties are important with
respect to the elimination of fraying of cut edges of
tufted carpets. To achieve complete anti-fray
characteristics, appreciable weight of adhesive coating
is normally required. me appearance of a carpet is
judged by hand and visual appearance after being laid.
Certain adhesive compositions can provide a better hand
to a carpet by introducing a certain degree of stiffness
in the carpet. In addition, carpet stiffness also tends
to prevent buckling, imparts a high degree of resilience
and prevents slipping on a polished floor. Dimensional
stability of a carpet is obtained by locking the fibers
together.
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1063278
In addition to other requirements, the adhesive
employed for carpets must have long effectiveness and
should have a high tensile strength. In addition, the
adhesive should not be degraded by water or other common
solvents which could be spilled on carpeting or with
which the carpet is likely to come in contact. Moreover,
the adhesive composition must be capable of application
by simple conventional techniques. m us, in addition to
good adhesion characteristics, adhesive compositions must
be judged by other criteria.
Some of the important characteristics of
adhesive compositions utilized for carpet backing
applications are T-peel, tuft lock and pill te~t. T-peel
is a value obtained when the secondary fabric backing is
pulled away from the primary ~abric backing. This value
is determined using a Scott tester. Adhesion of the scrim
or secondary fabric backing to the primary fabric is
referred to as the "peel strength". This expression is
used in its normal sense in the carpet manufacturing
industry to mean the force required to peel apart a strip
of two adhered components two inches wide which have been
aged 24 hours. It is measured by gripping components in
separate jaws of the Scott tensile tester and then moving
the jaws apart at a rate of two inches per minute. A
value of between 6 and 15 pounds is normally obtained.
Generally, the lighter the coating weight, the lower the
T-peel.
Tuft lock is a determination of the ability of
the rug backing adhesive composition to hold fiber to both
the primary and secondary fabric backing material. Tuft
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~063278
lock is determined by using a Scott tester to pull on one
tuft of the pile to measure the force required to pull the
tuft away from the primary and secondary fabric backing
material. Norm~lly, values for styrene-bùtadiene rubber
latex will vary from 6 to 15 pounds of pull. At 20 to 30
pounds of pull, the yarns used in the carpet industry
usually break.
The pilling test is a determination of the ability
of rug backing composition to completely enclose individual
fibers. Should the fibers in the construction not be
completely enclosed, mild rubbing of the carpet produces
loose strands of fibers which tend to form into a small ball
of fiber or a "pill".
m e invention will be illustrated by the following
examples, it being understood that there is no intention to
be necessarily limited by any details thereof, since
variations can be made within the scope of the invention.
Example I
A thixotropic adhesive composition was prepared by
blending 100 parts by weight of a liquid, hydroxyl-terminated
polybutadiene (Resin R-45HT, manufactured b~ ARC0 Chemical
Company) having an equivalent weight of 1180, a hydroxyl
content of o.85 milliequivalents per gram, and 0.05 weight
percent moisture; with 24 parts by weight of bisisopropanol
isophthalate ha~ing an equivalent weight of 141 grams; 196
parts by weight of naphthenic process oil ~cme S-60 oil,
manufactured by Atlantic Richfield); 310 parts by weight
of calcined kaolin ~Glomax H. E., manufactured by Georgia
Kaolin Company); 0.02 parts by weight of dibutyltin
dilaurate (T-12, manufactured by M&T Chemical Company); and
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1063278
43.8 parts by weight of diphenyl methane 4,4'-diisocyanate
(Isonate 143-L, manufactured by Upjohn Company), having an
equivalent weight of 144 grams. This formulation can be
used as an adhesîve composition for rug and carpet backing
applications.
Exam~le II
A thixotropic adhesive composition was prepared
by blending 100 parts by weight of R-45HT resin (identified
in Example I) with 17.7 parts by weight of bisisopropanol
aniline (Isonol C-100, manufactured by Upjohn Company)
having an equivalent wei~ht of 105 grams; 118 parts by
weight of saturated naphthenic process oil tTufflo 6024 Oil,
manufactured by Atlantic Richfield Company); 141 parts by
weight of talc (Mistron Vapor, manufactured by United
Sierra); 94 parts by weight of dry ground fatty acid treated
*
calcium carbonate (Quincy-2-Electro, manufactured by
Calcium Carbonate ~ompany); 0.25 parts by weight of
dibutyltin dilaurate; and 40.4 parts by weight~of diphenyl
methane 4,4' diisocyanate. The resulting adhesive
formulation gave good adhesion of jute backing to carpet at
a 15 ounce per square yard rate of application.
It was found that calcium carbonate (whiting)
can be introduced at higher levels than clay (Example I) or
talc without causing excessive viscosity increases and thus
can be used to contribute to lower cost. The use of higher
levels of calcium carbonate does not impart thixotropy and
contributes little to reinforcement; hence a balance
between the filler and calcium carbonate loadings must be
achieved.
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1063278
Examp]e III
An adhesive formulation was prepared by
blending 100 parts by weight of R-~5HT resin (identified
in Example I), 16.6 parts by weight of bisisopropanol
aniline; 100 parts by weight of a low viscosity saturated
naphthenic process oil ~ufflo 600~ Oil, manufactured by
Atlantic Richfield); 100 parts by weight of dry ground
calcium carbonate; 200 parts by weight of calcined kaolin;
1~06 parts b~ weight of water; 0.07 parts by weight of
dibutyltin dilauratej and 70.8 parts by wei~ht of
diphenyl methane 4~4'-diisocyanate.
m e resulting adhesive composition had a NCO/OH
ratio of 1.36. When applied at an application rate of 28
ounces per square yard, tuft lock equaled 12.7 pounds
(average) and 15 pounds (maximum). In addition, adhesion
of the backing was excellentj jute was destroyed when
attempting to delaminate double backed carpet.
Addition of water to the formulation of this
example prior to isocyanate cure was found to be very
beneficial for the following reasons: -
(a) The thixotropy of the uncured mix was
greatly increased, presumably due to floculation of kaolin
clay.
(b) Tuft lock was increased. m e same formula-
tion without added water and the equivalent amount of
diisocyanate had a maximum tuft lock of only 8.5 pounds.
The water reaction contributes urea linkages to the
polymer which should provide additional reinforcement.
(c) Water reaction with isocyanate results in a
chemical flow (foam formation) which appears to be
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1063Z78
i
beneficial since it increases the volume of the mix and
allows lower application rates, provides continued blow
after application which helps prevent voids between the 1,
carpet tufts, thereby resulting in more effective use of
the adhesive, particularly if the foam is crushed at the
proper stage of tackiness~ and chemical blow brings the
adhesive out of the tufts into contac~ with the secondary
backing thereby assuring good adhesion of the latter to
` the carpet e~en if initial penetration of the miX is
excessive.
Example IV
The following prepolymer precoat formulation
was pr~pared and applied to red nylon carpet. The
formulation consisted of 100 parts by weight of liquid,
hydroxyl-terminated polybutadiene prepolymer having 8.3
weight percent free ~CO groups (R-45HT resin identified
in Example I reacted with tolylene diisocyanate); 13.5
parts by weight of bisisopropanol anilinej 2.9 grams of
bisisopropanol bisphenol A; 100 grams of dry ground fatty
acid treated calcium carbonate; and 2.5 parts by weight
of 5A molecular sieve; 0.10 part by weight of dibutyltin
dilaurate.
me resulting prepolymer composition had a
NCO/OH ratio of 1.1 and was cured for 30 minutes at 220F.
It was applied to carpet at 28 ounces per square yard.
The resulting tuft lock was 20 pounds while bundle wrap
was 90 to 100.
Example V
A prepolymer precoat formulation was prepared
in the following manner and applied to red nylon carpet.
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~ 063278
The formulation consisted of 100 parts by weight of liquid,
hydroxyl-terminated polybutadiene prepolymer (identified
in Example IV); 13.5 parts by weight of bisisopropanol
aniline; 11.6 grams of bisisopropanol bisphenol A; 100
grams of dry ground fatty acid treated calcium carbonate;
2.5 parts by wei~ht of 5A molecular sieve; and 0.10 part
by weight o~ dibutyltin dilaurate.
The resul~ing prepolymer formulation had a
NCO/OH ratio of 1.1 and was cured 30 minutes at a
temperature of 220F. It was applied to tufted nylon
carpet at 28 ounces per square yard. The carpet had a
tuft lock of 20 pounds and a bundle wrap of 75.
Example VI
A prepolymer adhesive precoat formulation was
prepared in the following manner. 100 parts by weight of
liquid, hydroxyl-terminated polybutadiene prepolymer
(identified in Example IV) was mixed with 18 parts by
weight of bisisopropanol aniline; 0.10 part by weight of
dibutyltin dilaurate; 2 grams of silicone (GE SF 1156
surfactant), and 1 gram of water.
The resulting formulation had a NCO/OH ratio of
1.1. After being applied to blue nylon carpet the
formulation was treated for 30 minutes at a temperature
of 220F. me coating was applied at 32 ounces per
square yard. The resulting tuft lock was 15 pounds and
a bundle wrap of 90 was obtained.
Example VII
A prepolymer adhesive precoat formulation was
prepared by adding 100 parts by weight of liquid,
hydroxyl-terminated polybutadiene prepolymer (identified
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1063278
in Example IV); 4.3 parts by weight of bisisopropanol
aniline; 34.8 grams of bisisopropanol bisphenol A; 200
grams of dry ground fatty acid treated calcium carbonate;
2.5 grams of 5A molecular sieve; and 0~10 part by weight of
dibutyltin dilaurate.
The resulting prepolymer composition, having an
NCO/OH ratio of 1.1, was àpplied to blue nylon carpet and
heated ~or 30 minutes at a temperature o~ 220F. The
coating was applied at 28 ounces per square yard. A tuft
lock measur`ement of 18 pounds and an average bundle wrap
of 97 were obtained.
Example VIII
A prepolymer adhesive precoat formulation was
prepared by adding 100 parts by weight of liquid, hydroxyl-
terminated polybutadiene prepolymer (identified in Example
IV), 4.3 parts by weight of bisisopropanol aniline; 34.8
grams of bisisopropanol bisphenol A; 100 grams of dry
ground fatty acid treated calcium carbonate; 2-grams of
silicone (GE SF 1156 surfactant); 1 gram of water; 2.5
grams of 5A molecular sieve; and 0.10 part by weight of
dibutyltin dilaurate.
The resulting prepolymer composition, having an
NCO/OH ratio of 1.1, was applied to blue nylon carpet and
heated for 30 minutes at a temperature of 220F. m e
coating was applied at 28 ounces per square yard. A tuft
lock measurement of 14 pounds and an average bundle wrap
of 90 were obtained.
The compositions of the foregoing examples had
a viscosity between about 3,000 and about 100,000
centipoises as measured using a ~rookfield Viscosity Device,
26
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1063278
Model RVT, operated at 5 rpm using a number 5 spindle.
The thixotropic ratio of said compositions, determined by
viscosity measurements made at 1 and at 20 rpm, was
between about 1.3:1 and about 10:1.
From the foregoing it will be seen that this
invention is well adapted to obtain all of the ends and
objects hereinabove set forth, together with other
advantages which are obvious or inherent in the system.
Characteristics of formulations prepared in accordance
with the present invention include a 12 to 20 pound tuft
lock; 75 to 100 percent bundle wrap; a backing destroying
bond (i.e., the secondary fabric backing is torn upon
attempted delamination), a good hand which is soft to
firm without causing "boardiness"; a viscosity low enough
to allow pumping, mixing and ease of application but high
enough to prevent rapid uncontrolled penetration into the
fibers (i.e., a thixotropic formulation); and rapid
curing.
The thixotropic polyurethane adhesive composi-
tions of the present invention have several advantagesover the carboxylated styrene butadiene rubber latex
adhesives which have been used for so many years. First
the "cure" of carboxylated latex adhesive is primarily a
drying cycle which cannot be catalyzed in order to
shorten the time. In contrast, the thixotropic adhesive
compositions of the present invention cure through
reaction with diisocyanate which can be catalyzed to any
desired degree. Moreover, the cure, if sufficiently
catalyzed, will take place rapidly at lower temperatures
(e.g., 200F.) Rapid cure increases production and

1063278
greatly decreases capital investment since smaller curing
ovens are required. Fuel requirements are also greatly
reduced. The thixotropic adhesive compositions of the
present invention also have the advantage of having a
higher early green strength which thereby reduces the
chances of accidental delamination. Application of the
thixotropic adhesive compositions of the present invention
is also simpler than application of carboxylated latex
adhesives. The composition of the invention can be
discharged onto a carpet continuously by means of a hose
or nozzle and the resulting adhesive adjusted using a
conventional doctor blade to give the desired rate of
application and degree of penetration. Another advantage
is the fact that smaller and simpler equipment can be
used with the thixotropic adhesive compositions of the
present invention and this means a reduction in capital
investment and required operators, thus reducing production
costs.
Obviously, many modifications and variations of
the invention as hereinbefore set forth can be made
without departing from the spirit and scope thereof.
3o
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