Note: Descriptions are shown in the official language in which they were submitted.
41,~43-F
POLYURETHANE BACKED TEXTILES HAVING IMPROVED FLAME 2~7~21.
RETARDANCY AND METHOD FOR THE PREPARATION THEREOF
The present invention relates to polyurethane backed textiles having
improved flame retardancy. The present invention particularly relates to
polyurethane backed carpets and carpet tiles having improved flame
retardancy.
It is known in the art of preparing textile articles to use
polyurethanes in various forms. For example, U.S. Patent No. 4,296,159 to
Jenkines, et al. discloses preparing a tufted or woven article having a
unitary backing prepared by applying a polyurethane forming composition to
the underside of the tufted or woven article. A different form of
polyurethane backing is disclosed in U.S. Patent No. 5,102,714 to Mobley,
et al. wherein the polyurethane backing is a tacky adhesive. It is also
known to use polyurethane foam as a cushioning textile backing.
But preparing polyurethane backed textile articles is not always
trouble free. Preparing new articles can be particularly troubling. For
example, U.S. Patent No. 4,689,256 discloses that preparing a carpet from
nylon and poly vinyl chloride, each of which alone are ~low smoke~
materials can result in a carpet which is not low smoke. As in this
example, using new materials to prepare polyurethane backed textiles to
improve one property of the backed textile can result in another property
being degraded. When this occurs, it is sometimes necessary to modify
formulations to accommodate the new materials and yet maintain desirable
physical properties.
In order to meet contingencies such as the use of new textile
materials having high smoke values or just to comply with increasingly
stringent fire retardant requirements, it is desirable in the art to
prepare flame retardant polyurethane backed textile articles. It is also
desirable in the art to prepare polyurethane backed textile articles with
flame retardant polyurethane backings. And it is particularly desirable in
the art that the flame retardant polyurethane backings be useful in textile
applications having rigorous physical property requirements such as carpet
and carpet tiles.
-1-
41,443-F
X~278~1.
In one aspect, the present invention is a polyurethane backed textile
having improved flame retardancy comprising (A) a top-most textile facing
layer, (B) a polymeric textile backing prepared from a polyurethane
formulation including (lj a polyisocyanate, (2) a polyol, (3) a catalyst,
(4) a flame retardant selected from the group consisting of ZnC03, MgCO3
and mixtures thereof and, optionally, (5) a blowing agent.
In another aspect, the present invention is a polyurethane textile
backing comprising a polyurethane prepared from a formulation including (1)
a polyisocyanate, (2) a polyol, (3) a catalyst, (4) a flame retardant
selected from the group consisting of ZnC03, MgC03 and mixtures thereof
and, optionally, (5) a blowing agent.
Another aspect of the present invention is a method for preparing a
polyurethane backed textile having improved flame retardancy comprising
applying to a textile facing layer one or more polyurethane backing layers
prepared from a formulation including (1) a polyisocyanate, (2) a polyol,
(3) a catalyst, (4) a flame retardant selected from the group consisting of
ZnCO3, MgCO3 and mixtures thereof and, optionally, (5)a blowing agent.
In yet another aspect, the present invention is a polyurethane
formulation useful for preparing a polyurethane backed textile having
improved flame retardancy comprising (1) a polyisocyanate, (2) a polyol,
(3) a catalyst, (4) a flame retardant selected from the group consisting of
ZnCO3, MgCO3 and mixtures thereof and, optionally, (5) a blowing agent.
In one embodiment, the present invention is a polyurethane backed
textile having improved flame retardancy. Preferably the polyurethane
backed textile is a carpet or carpet tile. The polyurethane layer can take
several forms. In one form, it is a cellular polyurethane foam which acts
as an integral pad. This application of a polyurethane layer in a carpet
is disclosed in, for example, U. S. Patent No. 4,853,054, to Turner, et
al., which is incorporated herein by reference, and U.S. Patent No.
5,104,693 to Jenkines, et al., also incorporated herein by reference.
-` 2~27821.
In another form, the polyurethane layer of the present invention is a
microcellular polyurethane textile backing which, when applied to the
primary textile backing, can provide dimensional stability and serve to
anchor the textile tufts, also known as the face, to the textile primary
backing. The microcellular polyurethane of the present invention is useful
in the form of a layer adherent to the primary or secondary textile backing
serving to provide a suitable surface for the application of a polyurethane
foam wherein it is known as a precoat. This application of a polyurethane
backing layer in a carpet is disclosed in, for example, V.S. Patent No.
4,696,849 to Mobley, et al., which is incorporated herein by reference.
In yet another form, the polyurethane layer is a removable adhesive
such as that which is disclosed in U.S. Patent No. 5,102,714, also to
Mobley, et al, which is also incorporated herein by reference. In this form
the polyurethane adhesive can function to anchor floor coverings or to
anchor protective coverings such as a painter's drop cloth in place.
However, the removable character of the adhesive can allow the textile to
be removed easily.
When the polyurethane is in the form of a foamed polyurethane pad, it
can be prepared from a formulation including: (l) a polyisocyanate, (2) a
polyol, (3) a catalyst, and (4) a flame retardant, and additionally
including such materials as a filler; a catalyst, a surfactant, pigments,
molecular sieves, other flame retardants, antimicrobial materials and
blowing agents. The foamed polyurethane layer functions as an integral foam
pad thereby eliminating the need for a separate foam pad. The formulation
can be any foam formulation known to those skilled in the art of preparing
polyurethane foam for carpet applications to be useful. For example, the
formulation can be one of those disclosed U.S. Patent No. 4,853,05~ to
Turner, et al. additionally containing the flame retardant of the present
invention.
In the '054 patent to Turner, it is disclosed that the polyisocyanate
can be toluene diisocyanate or a prepolymer thereof with glycerine or -
trimethylolpropane or mixture thereof with an alkylene glycol or glycol
ether, the prepolymer having an average functionality of 2.03 to 2.2.
Preferably, the polyisocyanate is a mixture of a liquid methylene
-3- -
- . . : , - : -
L ' . , ~ "
41,443-F
~ 21Z7821
diphenyldiisocyanate (MDI) having an equivalent weight of 130 to 200 and
polyphenyl polymethylene polyisocyanate (also known as polymeric MDI and
hereinafter PMDI), the mixture having an average functionality of 2.03 to
2.2.
The polyol component of the foam formulation can be any polyol
or polyol mixture which can be used to prepare a foam which can withstand
the rigorous physical property and handling requirements of foams used in
carpet applications. The foamed polyurethane polyol component of a Turner
'054 type foam is preferably a polyol mixture h~ving as one part of the
mixture a polyol based on a C3-Cg alkylene oxide, which has an equivalent
weight of 1000 to 5000, and an internal poly(ethylene oxide) block or a
terminal ethylene oxide cap constituting 15 to 30 percent of the weight of
the polyol, or mixture of such polyols wherein the polyol or mixture
thereof has an average functionality of 1.8 to 2.2. The other portion of
the polyol mixture is preferably a minor amount of a low equivalent weight
compound having 2 active hydrogen containing groups per molecule.
Another example of the foamed form of the present invention is a
polyurethane foam prepared from a formulation such as those disclosed by
U.S. Patent No. 5,104,693 to Jenkines additionally including the flame
retardant of the present invention. In formulations of this type, the
polyol component can be at least one isocyanate reactive material having an
average equivalent weight of 1,000 to 5,000. The polyisocyanate can be any
polyisocyanate in an amount to provide an isocyanate index of 90 to 130,
wherein at least 30 percent by weight of the polyisocyanate is a soft
segment prepolymer which is the reaction product of a stoichiometric excess
of MDI or a MDI derivative and an isocyanate reactive organic polymer
having an equivalent weight from 500 to 5,000, the prepolymer having an
isocyanate group content of 10 to 30 percent by weight.
With either type of foam, the blowing agent is preferably air,
however, other gasses, such as carbon dioxide, and nitrogen can be used.
It is preferably injected into the polymer by frothing. The fillers can be
aluminum oxide trihydrate (alumina), calcium carbonate, barium sulfate or
mixtures thereof.
.:
-4-
... - ~ ; . ::
:. . . . . :, . ,
41,443-F
21~7821.
When the polyurethane is in the form of a microcellular polyurethane,
it can be prepared from a formulation including: (1) a polyisocyanate, (2)
a polyol, (3) a catalyst and (4~ a flame retardant, and additionally
including such materials as a filler, a surfactant, pigments, molecular
sieves, other flame retardants, antimicrobial materials and blowing agents.
Any formulation known to those skilled in the art of preparing
polyurethanes for carpet applications can be used to prepare the polymers
of the present invention except that they will additionally have a flame
retardant of the present invention. Polymers of this type are generally
applied to textiles as an unfoamed, non cellular layer which functions to
stiffen a textile and to adhere the tufts of the textile to the primary
backing. Particularly when the polyurethane layer is a precoat, the
polyisocyanate can be, for example, MDI, an MVI prepolymer or a modified
MDI material.
For example, the polyol component of a microcellular polyurethane can
include a first polyol which comprises a relatively high equivalent weight
polyol containing an average of 1.4-1.95 hydroxyl groups per molecule, of
which hydroxyl groups at least 30 percent are primary hydroxyls or a
mixture thereof with at least one additional relatively high equivalent
weight polyol containing at least 2.05 hydroxyl groups per molecule, of -which at least 30 percent are primary hydroxyls. Additionally the polyol
component can include a relatively low equivalent weight compound having 2
active hydrogen containing moieties per molecule. Desirably, the polyol
component has an average functionality of 0.97 - 2.03. The polyurethane is
preferably prepared such that the polyisocyanate and the polyol component
has an isocyanate index of 85-125.
When the polyurethane polymer of the present invention is prepared in ~ ~
the form of a removable adhesive, it can be prepared from a formulation - ~-
including: (l) a polyisocyanate; (2) a polyol; (3) a catalyst and (4) a
flame retardant. The formulation is applied in the form of a tacky
adhesive, preferably to a precoat layer. The polyisocyanate can have an
average functionality of 2.2 or less.
The polyol component of the removable adhesive can be a complex
admixture. It can have, as a first component, a mixture of a monoalcohol
-5-
: :~ ,.,; .~.-: ., : - .
41,443-F
21;;~7~32~.
and a polyether or polyester polyol, the mixture having an average actual
funct-onality of 2.2 or less, an equivalent weight of at least 50V and
containing from 10 to 70 mole percent monoalcohol. As a second component,
the polyol can have less than 10 weight percent, based on the weight of the
first polyol component of a compound or mixture of compounds having at
least two active hydrogen containing groups per molecule and an equivalent
weight from 30 to 500.
The polyurethane polymer adhesive, when prepared by the method of
U.S. Patent 5,102,70q to Mobley, is prepared with no more than 0.1 percent
water present. The polyurethane adhesive is prepared at an isocyanate index
of from 85 to 115. The adhesive can contain other additives such as
catalysts, and fillers. However, preferably, it contains no blowing agent.
If a blowing agent is used, the blowing agent is selected such that the
proscription of 0.1 percent water is not exceeded.
Polyurethane catalysts can be suitably used with all forms of the
present invention. The catalyst is preferably incorporated into the
formulation in an amount suitable to increase the rate of reaction between
the polyisocyanate and the polyol components of the present invention.
Although a wide variety of materials is known to be useful for this
purpose, the most widely used and preferred catalysts are the tertiary
amine catalysts and the organotin catalysts.
Examples of the tertiary amine catalysts include, for example,
triethylenediamine, N-methyl morpholine, N-ethyl morpholine, diethyl
ethanolamine, N-coco morpholine, l-methyl-4-dimethylaminoethyl piperazine,
3-methoxy-N-dimethylpropylamine, N,N-diethyl-3-diethyl aminopropylamine, :
and dimethylbenzyl amine. Tertiary amine catalysts are advantageously ~;
employed in an amount from 0.01 to 2 percent by weight of the polyol
formulation.
Examples of organotin catalysts include dimethyltin dilaurate,
dibutyltin dilaurate, dioctyltin dilaurate, and stannous octoate. Other
examples of effective catalysts include those taught in, for example, U.S.
Patent No. 2,846,408. Preferably the organotin catalyst is employed in an
amount from 0.001 to 0.5 percent by weight of the polyol formulation.
--6-
41,443-F
Z~7821
The flame retardants of the present invention are selected from the
group consisting of ZnCO3, MgCO3 and mixtures thereof. Preferably the
agent is ZnCO3. Either the ZnCO3 or the MgCO3 can include other materials.
For example, MgCO3 commonly includes minor amounts of Mg(OH)2 and is often
hydrated with the pentahydrate often predominating. Where other materials
are present in the ZnCO3 or MgCO3, preferably they are materials which are
low in iron and chloride salts as these species can interfere with urethane
reactions. The ZnCO3 and MgCO3 materials are solids and have particle
sizes sufficiently large to facilitate handling yet not so large as to make
it too difficult to admix them with the polyurethane backing formulation.
Preferably, the particle size distribution of the ZnCO3 and MgCO3 is such
that little dust is generated during handling but 99 percent will pass
through a 325 mesh screen.
Use of the flame retardants of the present invention is advantageous
for several reasons. Firstly, ZnCO3 and MgCO3 decompose at advantageous
temperature. ZnCO3 decomposes at 300C to produce CO2 which is believed to
be one mechanism whereby it retards flammability. MgCO3 similarly
decomposes at 800C. However MgCO3 dehydrates at 230C and Mg(oH12
decomposes to produce water at 350C. Polyurethane textiles can be subject
to temperatures of up to 160C during processing. Polyurethane backings
such as those used with the present invention begin to decompose at 180C.
A standard test for textiles, particularly for carpets and carpet tiles is
ASTM E 6~8-9la UStandard Test Method for Critical Radiant Flux of Floor-
Covering Systems Using a Radiant Heat Energy Source~. During this test,
the textile is exposed to temperatures of 600C and greater. The 230C
temperature where the flame retardants of the present invention can begin
decomposition is greater than the processing temperature of the textile, so
that the retardant does not decompose releasing CO2 prematurely. These
temperatures are near the polyurethane decomposition and testing
temperatures so that the flammability retarding agents can decompose in
time to improve flammability performance of the polyurethane backed
textiles. -~
Another reason that the flame retardants of the present invention are
advantageously used with polyurethane backed textiles is that as well as
--7--
41,443-F
-`` 21;~7821
being very economical, they can have minimal effect upon the curing times
of polyurethane formulations. The retardants will generally neither
substantially accelerate nor substantially slow polyurethane cure. This is
particularly important in polyurethane foam backed textile production. In
commercial carpet manufacturing operations, production equipment is often
sized based upon the cure time of the foam. For example, if it is
desirable to xun the textile through the foam backing application device at
a rate of x feet per second, and it is known that the foam will cure in y
seconds, then there needs to be x times y feet of carpet between the point
of foam application and the point at which the foam must be cured. If a
flame retardant were to significantly affect the cure time of a
polyurethane, it could result in undesirable quick cures wherein the
polymer might delaminate from the textile, or in a too slow cure wherein
the foam layer might be deformed or be squeezed out of the carpet and
damage the carpet facing.
The flame retardants of the present invention can be used alone, but
in some applications, they can also be used with other flame retardants.
For example, the flame retardants can be used with materials such as -
alumina. The primary reason that this can be desirable is that it allows
for minimal reformulation of the polyurethane backings. In a polyurethane
backed textile application which was adequate with only alumina, a change
in textile to one with poorer flammability can require that the
polyurethane backing be modified to supply additional flame retardancy to
compensate. Since the present invention can be used in conjunction with
alumina, a minor change to the formulation, adding an effective amount of
the retardants of the present invention, can be easily made.
The amount of flame retardants of the present invention used will
vary with the polyurethane formulations and choice of textiles for the
particular polyurethane backed textile application. However, generally,
where ZnC03 and MgC03 are used as sole flame retardants, they are used at
from 5 to 500 parts (by weight) per 100 parts of active hydrogen containing
materials. Preferably, they are used at from 10 to 300 parts ~by weight)
per 100 parts of active hydrogen containing materials. And more
preferably, they are used at from 50 to 225 parts (by weight) per 100 parts
of active hydrogen containing materials. Where they are used in
-8-
41,443-F
Z~7~32~.
conjunction with other flame retardants, they are used in an amount
effective to produce a polyurethane backed textile having Class I
flammability which is one having a critical radiant flux greater than or
equal to 0.4S watts/cm2. While this level of fire retardant will vary with
the textile and amount of flame retardant already present, it will
preferably be from 1 to 250, more preferably from 5 to 100, and even more
preferably from 5 to 50 parts (by weight) per 100 parts of active hydrogen
containing materials.
Alth~ugh they can be admixed with polyisocyanates, the flame
retardants of the present invention are desirably added to the non-
polyisocyanate component of the formulations of the present invention. For
example, when preparing a foam backed textile, the individual components of
the polyurethane formulation are admixed and added as a layer of preferably
uniform thickness on the textile. ~hile the flame retardants of the
present invention desirably do not substantially negatively affect the
physically properties of the polymers prepared therewith, they can increase
the viscosity of the polymer formulations in which they are included.
Often, this viscosity increase does not adversely affect handling, but
where it does, a surfactant can be used to alleviate the problem. Any
surfactant which does not adversely affect the polymer formulation can be
used for this purpose. Preferably the surfactant is an anionic/nonionic
surfactant. Care should be taken to use no more surfactant than is
necessary to avoid degrading polymer physical properties.
It is often preferable to premix all of the components except the
polyisocyanate (and the blowing agent when a gas is used) to form a ~B~
component. The polyisocyanate and the B component are admixed and then the
gas is blended in using, for example, an OAKES FROTHER* (*OAKES FROTHER is
a trade designation of the E.T. Oakes Corporation). The composition is
preferably applied prior to any significant level of curing using equipment
such as a doctor knife, air knife, or extruder to apply and gauge the
layer. In the alternative, the forming polyurethane can be applied by
forming it into a layer using a moving belt, allowing it to partially cure,
and then marrying it to the textile using equipment such as a double belt
laminator. After application of the foam layer, the polyurethane is cured
41,443-F
-
21;~82~.
by applying heat by means of an infrared oven, open flame forced draft
convection impingement oven, heated plates or the like.
Textiles useful with the present invention can include broadloom
carpet, automotive carpet, fabrics for automotive trim and automotive trunk
liners. In addition, the textiles useful with the present invention can
include synthetic playing surfaces, woven polymeric scrim, nonwoven
polymeric scrim, wall coverings, sheet polymers, and furniture covers. One
preferred embodiment of the present invention is carpet tile prepared by
incorporating the flame retardants of the present invention into a carpet
tile production process such as that disclosed in U.S. Patent No. ~,657,790
to Wing, et al. The '790 Wing, et al. patent is incorporated herein by ~
reference. :
Non-textile materials commonly used to prepare textiles can also be
used with the present invention. For example, latex precoats and adhesives
can be used with the present invention to prepare carpets. Other adhesives,
and coatings can be used with the present invention as long as they do not
substantially interfere with the flame retardant character of the
components of the carpets of the present invention.
In addition to carpets, the present invention can be used to prepare
furniture covers, and wall coverings. Useful applications of the present
invention include unusual applications such as a drop cloth having one side
coated with a removable adhesive.
The following examples are provided to illustrate the present
invention. The examples are not intended to limit the scope of the present
invention and they should not be so interpreted. Amounts are in weight
parts or weight percentages unless otherwise indicated.
E~ :;
A polyurethane backed textile was prepared with a precoat and a foam
backing, the formulations for which are disclosed in the Tables 1 and 2
below, according to the following steps:
-10 -
41,443-F
21;;~7~321.
a. A Precoat polyol/filler compound was prepared according to the
formulation below by placing the indicated amount of polyol(s) in a
suitably sized container;
b. The indicated amount of D-~0* calcium carbonate filler (*D-70
was a trade designation of Georgia Marble) was added to the polyol
while under high sheer agitation;
c. The indicated amount of H-36U* hydrated alumina (*H-36U is a
trade designation of Solem Industries) was added to the polyol
while under agitation;
d. The indicated amount of Zinc Carbonate (Mineral Research and
Development Corp.) or MagCarb H~ (*MagCarb H is a trade designation
of Marine Magnesium Company) was added to the polyol while under
agitation;
e. High shear agitation of the polyol/filler compound was continued
until a temperature of 50C was reached in order to thoroughly
disperse and break up agglomerate filler particles;
f. The polyol/filler compound was cooled to 20C;
g. The indicated amount of the isocyanate component was added to
the polyol/filler compound and the two thoroughly mixed;
h. The indicated amount of polyurethane catalyst was added to the
reaction mixture with agitation;
i. The reaction mixture was then spread onto the back of the
textile by means of a knife coating process and cured by means of
heated platens and/or an oven.
j. A foam polyol/filler compound was prepared according to the
formulation below and reacted with the isocyanate component using
the same procedures in steps a-h, above, except no metal carbonate
was used.
k. Air was metered into the reaction mixture which was frothed to a
foam of approximately 288 kg/M3 density.
1. The frothed foam reaction mixture was applied to the textile
according to step I above.
The textile was tested for radiant heat flux and the results are
displayed in Table 3 below. -
~:.
41,443-F
21~7~
A polyurethane backed textile was prepared and tested substantially
identically to Example 1 except that the formulation components indicated
in Tables 1 and 2 were used. Testing results are displayed in Table 3
below.
COMPARATIVE ~XAMPLE 3
A polyurethane backed textile was prepared and tested substantially
identically to Example 1 except that the formulation components indicated
in Tables 1 and 2 were used. Testing results are displayed in Table 3
below.
TABLE 1 - PRECOAT
. . ... .. , .. ~................. .
EXAMPLE 1 EXAMPLE 2 EXAMPLE
I
V-91201 85 85 85
lDPG2 15 15 15
¦D-703 61.5 61.5 70
¦H-36U4 135 135 135
¦ ZnCO~5 8.5 __ __
~ __ 10 __
~ 1.0 0.5 __
¦Catalyst8 0.2 0.2 0.2
S4 54 54
*Not an Example of the present invention.
1. VORANOL 9120* is a 2,000 molecular weight propylene oxide polyether
polyol having a nominal functionality of 2 (*VORANOL 9120 is a trade
designation of The Dow Chemical Company).
2. Dipropylene glycol .
3. D-70* is a calcium carbonate filler (*D-70 is a trade designation of
Georgia Marble).
4. H-36U* is a hydrated alumina filler (*H-36U is a trade designation of
Solem Industries).
5. Zinc Carbonate is available from Mineral Research and Development Corp.
-12-
41,44~-F
21~321
6. MagCarb H* iS an admixture having an approximate formulation of
(MgCO3)4 Mg(OH)2 5H2O (~MagCarb H iS a trade de~ignation of Marine
Magnesium Company).
7. Code 5027* is a anionic/nonionic surfactant (*Code 5027 is a trade
designation of Fibro Chem, Inc.).
8. Dibutyl tin maleate and ethylene diamine dispersed in a copolymer
polyol.
9. Is a polyisocyanate admixture of PMDI and MDI prepolymer having an NCO
percent of 27.6 and an isocyanate equivalent weight of 152.2.
TABLE 2 - FOAM
. _
EXAMPLE 1 EXAMPLE 2 EXAMPLE
I V-97411 90 90 90
¦DEG2 10 10 10 1
D-703 60 60 60
H-36U4 50 50 50 ¦
L-54405 0.38 0.38 0.38 l
Catalyst6 0.15 0.15 0.15 -¦
PMDI7 40.7 40.7 40.7
*Not an Example of the present invention.
1. VORANOL 9741* is a 4,800 molecular weight ethylene oxide capped
propylene oxide polyether polyol having a nominal functionality of 3
(*VORANOL 9741 is a trade designation of The Dow Chemical Company). -
2. Diethylene glycol
3. D-70* is a calcium carbonate filler (*D-70 is a trade designation of -
Georgia Marble).
4. H-36U* is a hydrated alumina filler (*H-36U is a trade designation of
Solem Industries).
5. L-5440* is a silicone surfactant (*L-5440 is a trade designation of
Union Carbide Corp.). -:~
6. Dioctyl tin diisooctylmercaptoacetate.
7. Is a polyisocyanate admixture of PMDI and an MDI prepolymer having an
NCO percent of 27.6 and an isocyanate equivalent weight of 152.2.
~; ~ . ~ ........ ..
: : : ", ~
41, 443-F
r~ 2127821
TABLE 3
= r~Mn] 1 E :~LC Z _ ,3,~
Critical .
Radiant 0.70 0.68 0.39
(w/ cnl2 ~ . .. ,.. , .. . .
*Not an Example of the present invention.
-14-
