A flame-retardant polyamide that is the polycondensation product of at least one dicarboxylic acid, at least one diamine and a flame-retarding carboxyphosphinic acid monomer, said polyamide comprising between about 0.10% and about 1.0% by weight of phosphorous. The polyamide can be formed into fibers for further fabrication into flame-retardant articles and textiles or directly molded or extruded into shaped articles.

FIELD OF THE INVENTION 
This invention relates to polyamides and, more particularly, to fire 
resistant phosphorous-containing polyamides. 
BACKGROUND OF THE INVENTION 
Fire resistance of polyamides is improved by the use of additives. Low 
molecular weight fire retardant additives, however, are lost from the 
polymer during its lifetime adversely affecting the ultimate performance 
of the products. Leaching out of the additives also causes blooming which 
affects the surface appearance of the product. The loss of such additives 
is very pronounced in polyamide fibers, the most prevalent end use of 
polyamides, due to their high surface area. 
Therefore, there has been considerable effort in the art to address the 
issue of fire retardant additive loss by using polymeric additives. One 
solution attempted is the use of high molecular weight additives. Although 
these additives are not as readily lost from the polymer, in part due to 
low vapor pressure, they present compatibility and miscibility problems 
that arise from fundamental thermodynamics. Further, incompatibility of 
additives increases with increase in the molecular weight of the additive. 
Unique problems arise for every polymer/additive pair. 
Another approach to polyamide fire resistance is the use of reactive 
polymer modifiers which provide the fire retardant properties to the 
polymer by becoming part of the polymer chain. Since these reactive fire 
retardant modifiers are chemically bound within the polymer chain, they 
are not lost with time or use, and are available to provide fire 
retardancy through the useful life of the polymer. 
Generally, halogenated compounds have been used as fire retardant modifiers 
for polyamides. These compounds typically inhibit the vapor phase 
combustion of fuel gases by a free radical reaction. However, there is 
considerable activity in the prior art to replace halogenated fire 
retardants. Industry is under pressure to move to environmentally 
friendly, non-fugitive fire retardants and to provide polymer products 
that don't release toxic gases during a fire. 
Phosphorus containing compounds can provide fire retardant properties by 
altering the pathway of a substrate's thermal degradation, promoting solid 
state reaction leading to carbonization or "char" formation. Methods of 
incorporating other phosphorous-containing additives into copolyamides are 
described in U.S. Pat. No. 4,032,517 (Pickett, Jr. et al.). Phosphoric 
acid, formed during degradation of phosphorus containing polymers, also 
reduces the permeability of the char thus providing an improved barrier to 
passage of air and fuel. Reactive phosphorus containing compounds which 
would form polymer bound polyamide fire retardants would, thus not only be 
useful but would be an attractive solution. Such polyamides would be 
particularly useful in industrial applications of polyamide fiber textiles 
such as carpet and upholstery. 
SUMMARY OF THE INVENTION 
This invention provides new polyamide compositions which exhibit improved 
fire resistance by incorporating fire retarding modifiers into the 
polyamide. 
Accordingly, a principal object of this invention is to provide polyamides 
wherein a comonomer in the copolyamides is a phosphorous-containing 
reactive non-halogen flame retardant (NHFR). 
Other objects of this invention will in part be obvious and will in part 
appear from the following description and claims. 
These and other objects are accomplished by the polyamide of this 
invention, which is the polycondensation product of at least one 
dicarboxylic acid, at least one diamine and a carboxy-phosphinic acid, 
said carboxy-phosphinic acid being a source of flame-retardant phosphorus 
and having the formula: 
##STR1## 
wherein R is saturated or unsaturated, straight chain, branched or cyclic 
C.sub.1 to C.sub.15 alkylene, or a C.sub.5 to C.sub.15 arylene or 
aralkylene, wherein the alkylene portion is saturated or unsaturated, 
straight chain branched or cyclic, and R.sub.1 is saturated or 
unsaturated, straight chain, branched or cyclic lower alkyl, lower alkoxy 
or aryl, alkylaryl or alkoxyaryl, wherein the alkyl portion is saturated 
or unsaturated, straight chain branched or cyclic; and wherein R and 
R.sub.1 may contain one or more O or S atoms; such that the polyamide 
comprises between about 0.10% and about 1.0% by weight of phosphorous. 
DETAILED DESCRIPTION OF THE INVENTION 
Polycondensation of at least one dicarboxylic acid, at least one diamine 
and a carboxy-phosphinic acid produce the polyamide of the invention. The 
carboxy-phosphinic acid used in the invention has the formula: 
##STR2## 
wherein R is saturated or unsaturated, straight chain, branched or cyclic 
C.sub.1 to C.sub.15 alkylene, or a C.sub.5 to C.sub.15 arylene or 
aralkylene, wherein the alkylene portion is saturated or unsaturated, 
straight chain branched or cyclic, and R.sub.1 is lower alkyl, lower 
alkoxy, allyl, aryl alkylaryl or alkoxyaryl, wherein the alkyl portion is 
saturated or unsaturated, straight chain branched or cyclic, and wherein R 
and R.sub.1 may contain one or more O or S atoms; such that the polyamide 
comprises between about 0.10% and about 1.0% by weight of phosphorous. 
The term "polyamide" in this description is intended to encompass 
copolyamides also. The term "lower alkyl" and "lower alkylene" means 
straight or branched chain alkyl and alkylene, respectively, having 1 to 7 
carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, 
methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, 
and the branched chain isomers thereof. The term "lower alkoxy" means 
straight or branched chain alkoxy having 1 to 7 carbon atoms such as 
methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy and the 
branched chain isomers thereof. The term "allyl" as used herein means the 
1-propenyl radical, --CH.sub.2 --CH.sub.2 .dbd.CH.sub.2. The term "aryl" 
means substituted and unsubstituted phenyl and naphthyl wherein the 
substituents comprise lower alkyl, lower alkoxy, allyl and halo moieties. 
The terms "alkylaryl" and "alkoxyaryl" mean combinations of lower alkyl 
and aryl, and lower alkoxy and aryl, respectively, as defined herein. The 
terms "aryl", "alkylaryl" and "alkoxyaryl" are intended to comprise 
C.sub.6 to C.sub.20 moieties. The term "halo" means fluoro, chloro, bromo, 
or iodo. 
In the typical production of polyamides, a dicarboxylic acid, or lower 
alkyl ester thereof, is condensed with a diamine according to the 
following formula: 
EQU HOOC--(CH.sub.2).sub.x --COOH+n H.sub.2 N--(CH.sub.2).sub.y --NH.sub.2 
.rarw..fwdarw.OC--(CH.sub.2).sub.x --CO--HN--(CH.sub.2).sub.y --NH!.sub.n 
+2n H.sub.2 O 
Those of ordinary skill in the art recognized that by mixing more than one 
dicarboxylic acid and more than one diamine a variety of polyamides and 
copolyamides are prepared. The most frequently used dicarboxylic acids are 
adipic and sebacic acids and the most frequently used diamine is 
hexamethylene diamine. Methods of forming polyamide resin compositions 
including dicarboxylic acids and diamines that can be used in the 
production of the polyamide of this invention are described in U.S. Pat. 
No. 4,298,518 (Ohmura et al.), the contents of which are hereby 
incorporated into this description. The flame-retardant polyamide of this 
invention can comprise structural units derived from more than one 
dicarboxylic acid and more than one diamine. In the polyamide of the 
invention, the carboxy-phosphinic acid described above replaces a portion 
of the dicarboxylic acid typically used, thus forming the modified 
polyamide. 
The carboxy phosphinic acids which provide the flame-retardant 
phosphorous-containing structural units of the polyamides of this 
invention are described in U.S. Pat. No. 4,081,463 (Birum et al.) and U.S. 
Pat. No. 3,941,752 (Kleiner et al.), the disclosures of which are hereby 
incorporated into this description. In a preferred embodiment of the 
polyamide of this invention, R.sub.1 is C.sub.6 H.sub.5 and R is 
--CH.sub.2 --CH.sub.2 --. The phosphinic acid 
2-carboxyethyl(phenyl)phosphinic acid, referred to herein as "CEPPA", is 
used to provide the preferred flame-retardant phosphorus-containing 
structural unit. 
The polyamide of the invention typically comprises between about 0.10% and 
about 1.0% by weight phosphorous, preferably between about 0.16% and about 
0.56% by weight phosphorous. In a particularly preferred embodiment the 
polyamide comprises about 0.25% by weight phosphorous. 
In general, the polyamides of this invention may be prepared by 
polycondensation reaction of difunctional polyamide-forming reactants by 
conventional techniques. Such difunctional polyamide-forming reactants 
include but are not limited to diamines and dicarboxylic acids, 
amide-forming derivatives of dicarboxylic acids, lactams, and 
aminocarboxylic acids or amide-forming derivatives of aminocarboxylic 
acids. Generally, when one or more of the difunctional reactants is an 
aromatic diamine, such as para- or meta-phenylene diamine, the polyamide 
is prepared by conventional solution polymerization by reaction of the 
diamine with the acid chloride of the dicarboxylic acid in the appropriate 
solvent (e.g., dimethylacetamide). Interfacial polymerization may also be 
used. 
Conventional techniques for polycondensation, such as melt polymerization 
or solution polymerization, are the preferred methods of making the 
modified polyamides of the invention. Melt polymerization utilizes an 
aqueous solution of an appropriate mixture of two or more 
diamine-dicarboxylic acid salts that is heated to remove water and effect 
polymerization. Each salt is conveniently prepared by mixing substantially 
equimolar amounts of dicarboxylic acid and diamine in water. The salts can 
be isolated from their respective solutions and combined in water to 
provide an aqueous solution of salts or the individual salt solutions may 
be combined. As used herein, the term "salt" refers to both isolated salts 
and salt solutions. 
The salts are combined in a polymerizer such as an autoclave or other 
similar reaction vessel. By varying the concentrations of each salt 
solution, the weight of phosphorus in the polyamide is controlled. The 
total charge to a polymerizer or autoclave is typically 50-75% reactants 
and 50-25% water. For example, an aqueous slurry of salts can be added to 
a stainless steel, high-pressure autoclave which has previously been 
purged of air with purified nitrogen. The temperature and pressure are 
slowly raised, for example to about 220.degree. C. and about 250 psig. 
Then the temperature is typically increased, for example to approximately 
240.degree. C. while the pressure is maintained at approximately 250 psig. 
The temperature is then raised above the melting point, approximately 
275.degree.-285.degree. C., while the steam condensate is continuously 
removed. The pressure is then gradually reduced to atmospheric over an 
approximately 25 minute period. The polymer melt is then allowed to 
equilibrate for approximately 30 minutes at about 275.degree.-285.degree. 
C. The minimum temperature employed for melt polymerization of the 
copolyamides of this invention is usually about 270.degree. C. 
Scheme 1 depicts a two salt solution method to form a preferred embodiment 
of the invention. In Scheme 1, CEPPA is combined with hexamethylene 
diamine to form a first salt solution. Separately, hexamethylene diamine 
and adipic acid are combined to form a second salt solution, a Nylon 6,6 
salt solution. Polyamide copolymers of CEPPA and nylon-6,6 are then 
prepared by polymerizing a mixture of the two salt solutions. In a 
separate preferred embodiment of the invention, in particular where lower 
levels of weight percent of phosphorus are desired, a slurry of diamine, 
dicarboxylic acid and carboxyphosphinic acid can be formed and directly 
polycondensed without the formation of separate salt solutions. 
##STR3## 
The present invention thus also provides a process for making a 
flame-retardant polyamide which comprises polycondensing at least one 
dicarboxylic acid, at least one diamine and a carboxy-phosphinic acid, 
said carboxy-phosphinic acid having the formula: 
##STR4## 
wherein R and R.sub.1 are the same as defined above. 
A preferred embodiment of the process comprises polycondensing a first salt 
of diamine and dicarboxylic acid with a second salt of diamine and the 
carboxy-phosphinic acid defined above, such that the resulting polyamide 
comprises between about 0.1% and about 1.0% by weight of phosphorous. 
In a separately preferred embodiment, the polyamide produced by the melt 
polymerization technique described above is further solid state 
polymerized in order to increase the molecular weight of the polyamide. 
Conditions which would be appropriate to achieve solid state polymerization 
are known to those of ordinary skill in the art. Typically, solid state 
polymerization comprises subjecting a finished polymer pellet to elevated 
temperatures for extended periods of time in order to promote the further 
polymerization of shorter chain polymer molecules, driving off additional 
water, and thereby increase the molecular weight of the polymer. For 
example, polyamide pellets produced by the melt polymerization techniques 
above can be loaded into an autoclave and held at an elevated temperature 
which is below the melting point of the polyamide, such as between 
200.degree. C. and 250.degree. C., for any length of time desired so as to 
produce the molecular weight desired. Example 4 shows the production of 
preferred embodiments of the invention where a copolyamide having a 
molecular weight of 19,700 and containing 0.36% by weight phosphorus, is 
separately solid state polymerized at 220.degree. C. for two, three, and 
four hours to produce copolyamide molding resins having molecular weights 
of 34,800, 40,800, and 48,100, respectively. 
The polymer is typically extruded from the polymerizer, drawn through a 
quench bath of water, and then taken up as fiber on a bobbin, for example 
being wound with a Leesona winder. This fiber bundle can then be drawn to 
approximately 3 to 5 times its original length, for example over a hot pin 
at elevated temperatures such as between 60.degree.-90.degree. C. The 
resultant fiber typically has a denier between 50-150. In a preferred 
embodiment the resultant fiber has a denier of 90-100. 
The polyamides of this invention are most often drawn into synthetic fibers 
to make articles such as textiles, filter cloth, ropes, nets, conveyor 
belts, electrical insulation and tire cords. Polyamide in pellet form 
(molding resin) can also be injection molded or melt cast into articles 
such as bearings, gears, valve plates, pipes, housings, films, nuts, and 
bolts. The molding resins of the invention, as well as any fibers, 
textiles or articles comprising the molding resins, are thus rendered 
flame retardant or fire resistant. As used herein, the terms "flame 
retardant" and "fire resistant" are synonymous. 
In a preferred embodiment, the polyamides of this invention are formed into 
synthetic fibers which can be used as textiles for such applications as 
flame retardant clothing, upholstery, carpeting and wall covering. The 
following examples are provided to illustrate the invention and are not 
intended, and should not be interpreted, to limit in any way the invention 
which is more fully defined in the claims. 
The techniques for measurement of polymer melting point, intrinsic 
viscosity, moisture regain, boiling water-shrinkage, fiber denier, 
tenacity, elongation, and modulus are well known to those of ordinary 
skill in the art. Ridgway, J. S., J. Applied Polymer Science, Vol. 18, 
pages 1517-1528 (1974) discusses such techniques in the production of 
polyamides. The fiber properties of denier, tenacity, elongation, and 
modulus of the drawn fibers prepared according to the invention were 
determined on an Instron tester at a rate of extension of 100%/min with 
the use of a 1-in. gauge length and are typically measured at 72% relative 
humidity (RH), and 74.degree. F. 
The following terms are used in the Examples: 
"RV" - relative viscosity 
"NH.sub.2 & CO.sub.2 H" - content in milliequivalents/g 
"MW" - molecular weight (daltons) 
"Ten" - tenacity (grams per denier, "gpd") 
"Elong" - % elongation 
"Mod" - modulus (gpd)

EXAMPLE 1 
Preparation of CEPPA-hexamethylene Diamine Salt. 
CEPPA-hexamethylene diamine salt was prepared by adding a solution of 
0.0147 moles of the hexamethylene diamine ("HMD") in 8 mls of ethanol to a 
solution of 0.014 moles of CEPPA diacid in 7 ml of ethanol. The diamine 
solution was added dropwise over a six minute period. The temperature of 
the reaction mass increased from 24.2.degree. C. to 38.1.degree. C. in six 
minutes going through a maximum of 42.1.degree. C. in about three minutes. 
Melting point range of the salt was between 220.degree.-226.degree. C. and 
a pH of 7.06 was measured for a 1% salt solution. 
Using ethanol as the solvent the salt crystallizes out of solution. The 
salt solution can also be prepared by dissolving the reactants in water 
instead of ethanol and then can be used directly by mixing with 
HMDA/adipic acid salt solution prepared in Example 2 below. Since the 
resulting salt is soluble in water, it can be crystallized by addition of 
ethanol. 
EXAMPLE 2 
Preparation of Hexamethylenediamine .backslash. Adipic Acid Salt 
Adipic acid (14.60 g; 0.100 mole) was placed in a 250 ml Erlenmeyer flask, 
dissolved in 110 ml absolute ethyl alcohol by warming and cooled to room 
temperature. A solution of 11.83 g (0.12 mole) hexamethylenediamine (b.p. 
90.degree.-92.degree. C./14 mm, m.p. 41.degree.-42.degree. C.) in 20 ml 
absolute ethyl alcohol is added quantitatively to the adipic acid 
solution. The mixing is accompanied by spontaneous warming and 
crystallization soon occurred. After standing overnight, the salt was 
filtered, washed with cold absolute alcohol, and air-dried to constant 
weight. The yield is 25.5 g. (97%). A 2% excess of diamine was used to 
promote a salt that is rich in diamine, since this is the more volatile 
component and may be lost during salt drying or during polycondensation. 
The white crystalline salt melts at 196.degree.-197.degree. C. and has a 
pH of about 7.6, determined on a 1% solution of salt in water, using a pH 
meter. 
A pH tolerance of 0.5 unit is usually acceptable, especially on the high 
side because of the possible diamine loss noted above. Salt imbalance may 
be corrected by recrystallization or the after-addition of a small amount 
of the indicated component. Salts of low and high pH may be mixed to give 
a balanced composition of the proper pH. 
EXAMPLE 3 
Melt Polymerization of Salt Solutions 
A 75% aqueous slurry of salts was added to a stainless steel, high-pressure 
autoclave which was previously purged of air with purified nitrogen. The 
temperature and pressure are slowly raised to 220.degree. C. and 250 psig. 
The temperature was then increased to 240.degree. C. while the pressure 
was maintained at approximately 250 psig. The temperature was then raised 
above the melting point, approximately 275.degree. C.-285.degree. C., 
while the steam condensate was continuously removed. The pressure was then 
gradually reduced to atmospheric over an approximately 25 minute period. 
The polymer melt was allowed to equilibrate for approximately 30 minutes 
at about 275.degree. C.-285.degree. C. The minimum temperature employed 
for melt polymerization of the copolyamides of this invention is usually 
about 270.degree. C. 
Table 1 provides a examples of weight ratios of salt solutions useful for 
producing representative examples of copolyamides of this invention. 
TABLE 1 
______________________________________ 
Wt. % P CEPPA/HMDA salt 
HMDA/AA salt 
______________________________________ 
0.16 1 65 
0.25 1 41 
0.32 1 32 
0.36 1 28 
0.54 1 19 
1.00 1 10 
______________________________________ 
Properties of the fibers drawn from the copolymer of this invention 
containing 0.24% by weight phosphorous are compared with the fibers from 
nylon 6,6 control in Table 2. The numbers in parentheses demonstrate the 
measurements of properties after boiling water extraction for 30 minutes. 
Exposure to boiling water is used to determine the extent to which CEPPA 
is polymer-bound since CEPPA, by itself, is water soluble. Phosphorus 
levels were also tested for the copolymer containing 0.24% by weight 
phosphorous which showed levels of phosphorous of 2396 ppm before and 2193 
ppm after boiling water extraction. The 200 ppm loss in phosphorus levels 
is attributed to the loss of phosphorus supplied by optional 
polymerization co-reactants such as benzene phosphinic acid and manganese 
hypophosphate, which are not polymer bound and are easily washed away in 
the test. Levels of phosphorus are determined using techniques well known 
to those of ordinary skill in the art such as X-ray diffraction and 
.sup.31 P-NMR. 
TABLE 2 
__________________________________________________________________________ 
Relative Mol. 
Melt. Elongatio 
Polymer 
Viscosity 
NH.sub.2 & CO.sub.2 H 
Wt. Point 
Tenacity 
n Modulus 
__________________________________________________________________________ 
Nylon 6, 6 
43 33/87 40,400 
256.degree. C. 
3.2 91.2 25.2 
control 
(41.7) 
(33/89) (2.05) 
(76.7) 
(15.6) 
Copolymer 
25 94/115 27,300 
258.degree. C. 
3.21 86.3 32 
(0.24 wt % 
(25) (82.5/115) (2.05) 
(77) (15.6) 
CEPPA) 
__________________________________________________________________________ 
The data in Table 2 show that although the molecular weight of the 
copolymer containing CEPPA is relatively low compared to the nylon 
control, its physical properties are very similar to the nylon 6,6 
control, indicating that the molecular weight required for critical 
entanglement chain length has been achieved. 
No significant change in the phosphorus content and total retention of 
relative viscosity suggests that phosphorus is bound to the polymer chain 
and the copolymer's hydrolytic stability is very similar to nylon 6,6. 
This is further supported by the fact that the mechanical properties of 
the copolymer, i.e., tenacity, elongation and modulus, after the 30 minute 
water boil are nearly identical to those of the nylon 6,6 control. 
EXAMPLE 4 
Solid State Polymerization 
The molecular weights of the copolymer containing 0.25% by weight 
phosphorus may be acceptable for some fiber and thermoplastic applications 
but, if needed, molecular weight could be further increased to the desired 
level by solid state polymerization. 
Table 3 shows properties of nylon 6,6 copolymers with CEPPA including the 
molecular weights of the copolymers containing different amounts of 
phosphorus, obtained by the melt condensation process and by further solid 
state polymerization at 220.degree. C. "MW #1" and "MW #2" represent the 
average molecular weight of the polymers before and after solid state 
polymerization. The three values presented for the polymer containing 
0.36% CEPPA represent readings after solid state polymerization for two, 
three, and four hours, respectively. 
TABLE 3 
______________________________________ 
Polyamide 
Weight % P MW #1 MW #2 
______________________________________ 
1 0.16 28,000 70,700 
2 0.32 22,000 82,600 
3 0.36 19,700 34,000 
40,800 
-- 48,000 
4 0.54 11,000 27,000 
______________________________________ 
Although the molecular weights of the copolymers decrease with increasing 
CEPPA content, as shown above, polymer compositions can be solid state 
polymerized to higher molecular weight. Molecular weight can be adjusted 
to the desired level by varying the time, temperature or the catalyst 
during the solid state polymerization. For example, as shown in Table 3, a 
copolymer of 19,700 molecular weight, containing 0.36% by weight 
phosphorus, can be solid state polymerized to a molecular weight of 
34,800, 40,800, or 48,100 by varying the length of time of the solid state 
polymerization step. 
EXAMPLE 5 
Fiber Flammability Test 
Flammability of the nylon control and the copolymer was tested by a method, 
devised by John Stoddard, O. A. Pickett, C. J. Cicero and J. H. Saunders 
Text. Res. J., Vol. 45, p. 454 (1975). An eighteen inch long bundle of 
fiber was held vertically and ignited. The fiber bundle was relit each 
time the flame extinguished. The number of relights required for a 
complete burn is the measure of flame resistance of the fiber. Nylon 6,6 
containing 0.36 weight % phosphorus required 30 relights to achieve a 
complete burn compared to 16 relights for the nylon control thus 
indicating substantial improvement in fire retardancy for the modified 
polyamides of this invention. 
EXAMPLE 6 
Finished Article Flammability Tests 
I. Introduction 
Flammability tests were conducted on floor covering material made from 
polyamide fibers of this invention in accordance with the American Society 
for Test and Materials response standard E 648-95a. Critical Radiant Flux 
of Floor-Covering Systems Using a Radiant Heat Energy Source. This method 
is sometimes referred to as the flooring radiant panel test. 
This test method, which has been approved for use by agencies of the 
Department of Defense and for listing in the DoD Index of Specifications 
and Standards, is technically identical to the method described in NFPA 
Number 253. The test results are used as elements of a fire-hazard 
assessment or a fire-risk assessment which also takes into account all of 
the factors pertinent to an assessment of the fire hazard or fire risk of 
a particular end use of polymer fibers. 
The flooring radiant panel test measures the level of incident radiant heat 
energy at flame-out of a horizontally mounted complete floor covering 
systems that duplicate or simulate accepted installation practices. The 
testing methods provide a basis for estimating one aspect of fire behavior 
of systems installed, for example, in corridors or exit ways. Imposed 
radiant flux simulates thermal radiation levels likely to impinge on the 
floors of a building whose upper surfaces are heated by flames or hot 
gases, or both, from a fully developed fire in an adjacent room or 
compartment. 
II. Preparation of Samples 
Floor covering made from the flame retardant polyamide fibers of the 
claimed invention, referred to as "Sample A" were compared to floor 
covering made from polyamide fibers containing no flame retardant, 
referred to as "Control". Sample A was prepared according to the 
procedures outlined in the Examples above including solid state 
polymerization. Tables 4 and 5 show the physical characteristics of the 
fibers. 
TABLE 4 
______________________________________ 
PHOSPHORUS CONTRIBUTION (ppm) 
Theo/ NH2/ 
Item BPA MHP CEPPA Found RV COOH 
______________________________________ 
Control 200 15 0 215/246 
51 59/77 
Sample A 200 15 1850 2063/2032 
29 198/70 
Sample A (solid state) -- 68 -- 
______________________________________ 
"BPA" benzene phosphinic acid 
"MHP" manganese hypophosphate 
TABLE 5 
______________________________________ 
Fiber Spinning and Draw Jet ID 
Spinning 
Tenacity/% Elongation 
Jet Texturing 
______________________________________ 
Control 1.05/440 Yes 
Sample A (solid state) 
1.03/452 Yes 
______________________________________ 
III. Test Procedure 
A gas and air fueled radiant heat energy panel is mounted in the test 
chamber at a 30.degree. angle to the horizontal plane of the specimen. The 
panel generates an energy flux distribution ranging along the length of 
the test specimen from a nominal maximum of 1.0 W/cm.sup.2 to a minimum of 
0.1 W/cm.sup.2. Air flow through the chamber is controlled at a velocity 
of 250 feet per minute. The test is initiated using a gas pilot burner 
brought into contact with the specimen and extinguished after a specified 
time. 
All floor covering specimens were cut pile construction containing a woven 
synthetic secondary back. The coverings were applied over cushion underlay 
(40-ounce Hair/Jute) on a GRC board subfloor. Each floor-covering system 
was tested in triplicate, each specimen measuring 20 cm wide by 100 cm 
long. Prepared specimens were conditioned a minimum of 96 hours in an 
atmosphere maintained at 71.+-.2.degree. F. and 50.+-.3% relative 
humidity. Chamber operating conditions were verified on the day of the 
test by measuring the flux level at the 40 cm mark. An incident flux level 
of 0.50.+-.0.02 W/cm.sup.2 indicates proper operation and calibration of 
the test chamber. 
Specimens were placed in the chamber and allowed to preheat for 5.0 minutes 
followed by a 5.0-minute application of the pilot burner. The specimens 
were allowed to burn until they self-extinguish, at which time they were 
removed from the test chamber and the farthest point of flame propagation 
measured. The critical radiant flux is determined from the flux profile 
determined during calibration of the test instrument. 
IV. Results 
The test results, provided in Tables 6 and 7, represent the average value 
of the three specimens tested expressed in terms of Critical Radiant Flux 
in units of W/cm.sup.2. All pertinent individual specimen data are 
presented in Table II. The flux profile shown in the figure is typical of 
that determined during calibration of the flooring radiant panel 
instrument used for this test. 
The general classification for the floor-covering system identified in this 
report is based on criteria published in the NFPA 101 Life Safety Code. 
The GSA classification is based on criteria published In Amendment 6 to 
GSA Solicitation Number 3FNH-92-F301-N, effective Jun. 16, 1994. However, 
care must be exercised in their use as a material may be otherwise 
classified by the authority having jurisdiction. 
TABLE 6 
______________________________________ 
Control Test Results 
#1 #2 #3 
______________________________________ 
Maximum Burn Distance (cm) 
100.0 100.0 100.0 
Time to Flame Out (min.) 
86.6 88.0 84.1 
Critical Radiant Flux (W/cm.sup.2) 
&lt;0.11 &lt;0.11 &lt;0.11 
______________________________________ 
Average Critical Radiant Flux 
&lt;0.11 W/cm.sup.2 
______________________________________ 
TABLE 7 
______________________________________ 
Sample A Test Results 
#1 #2 #3 
______________________________________ 
Maximum Burn Distance (cm) 
51.7 50.0 49.8 
Time to Flame Out (min.) 
24.9 24.0 23.6 
Critical Radiant Flux (W/cm.sup.2) 
0.33 0.35 0.35 
______________________________________ 
Standard Deviation 0.0123 
Average Critical Radiant Flux 
0.34 W/cm.sup.2 
NFPA 101 Classification 
Type II 
GSA Classification Class B 
______________________________________