Note: Descriptions are shown in the official language in which they were submitted.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
LIGHT AND THERMALLY STABLE POLYAMIDE
Description
This invention relates to a polyamide that achieves high light
and heat stability. More particularly, this invention relates to
a modified nylon polymer containing a hindered piperidine
compound and a chain regulator, wherein the modified nylon poly-
mer has an improved stability to light and heat.
It is known that when unaided nylon is exposed to light and/or
heat, the nylon discolors and loses its physical properties such
as strength retention and resistance to elongation. Therefore,
the addition of light and/or heat stabilizers to nylon is neces-
sary in some cases in order for nylon to achieve acceptable per-
formance. The stabilizers may be added before, during, or after
polymerization. The conventional stabilizers are admixed with the
polymer and are not bound to the polymer chain; therefore, during
processing or use of the polyamide, the stabilizers can readily
migrate out of the polymer, evaporate, or be washed out. This
means that the activity of the stabilization is reduced in an un-
desired manner, and impurities are released to the surroundings
(e. g., air, dye bath, etc.).
Various organic stabilizers are known for use with nylon and ar-
ticles manufactured therefrom. One problem, however, is that
organic stabilizers such as, for example, hindered phenols, are
expensive and have limited effectiveness.
Inorganic stabilizers are generally less expensive and more ef-
fective than organic stabilizers; however, inorganic stabilizers
suffer from a different set of problems. Typically, common
inorganic stabilizers such as, for example, copper compounds,
cause problems during processing. For example, in the melt
extrusion process, copper compounds, may be reduced to insoluble
elemental copper. Formation of elemental copper reduces produc-
tion efficiency and adds significant equipment maintenance costs.
Furthermore, the removal of copper deposits generates environmen-
tally-undesirable effluent. In other processes such as, for
example, the treatment of automotive nylon fibers with copper
complexes in a dye bath, the excess copper complexes that are in
the bath also produce environmentally-undesirable effluent.
Commonly owned United States Serial No. 08/804,312 relates to a
process for preparing photochemically-stable, dyed nylon composi-
tions comprising providing to a dye bath a shaped article of
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
2
poly(epsilon-caprolactam) hydrolytically polymerized in the pre-
sence of water and a hindered piperidine derivative and, in the
dye bath, dyeing the shaped article with one or more metalized or
nonmetalized acid dyestuffs.
Commonly owned United States Serial No. 60/045,269 relates to a
process for making stabilized solution-dyed fibers by melting a
polyamide comprising amide monomers polymerized in the presence
of at least one hindered piperidine compound and coloring the
melted polyamide with a colorant.
A PCT application, International Application No. PCT/EP 95/01349,
describes an inherently stabilized polyamide containing at least
one triacetone diamine compound having a primary amino group
(-NH2) that reacts with a carboxy end group of the polyamide mole-
cule during polymerization, thus rendering the polymer light and
heat stable.
An essay in Poly. Deg. And Stab. 21, 251-262 (1988) describes the
improvement of the light stability of polyamide 6/6 by the addi-
tion of 2,2,6,6-tetramethylpiperidin-4-of ("TMP"). In a reconden-
sation of the TMP-containing polyamide 6/6 in the melt at 275°C
under an atmosphere of water vapor, the authors claim that TMP
reacts with the carboxyl end groups of the polyamide.
A need, therefore, exists for a modified polyamide that reduces
the need for copper-based stabilizers and that avoids discolora-
tion, i.e., yellowing after exposure to light and/or heat. Furt-
hermore, it would be desirable to produce a polyamide having an
improved resistance to yellowing upon exposure to light and/or
heat, especially in engineering plastics applications.
It is an object of the present invention to provide a modified
polyamide that avoids discoloration after exposure to light and/
or heat.
Another object of the present invention is to reduce the need for
copper-based stabilizers in polyamides.
Yet another object of the present invention is to provide an en-
vironmentally-friendly and efficient process of producing a
modified polyamide that is both light and heat stable.
Thus, according to one embodiment of the present invention, there
is provided a method of making a light and thermally stable poly-
amide with built-in stabilizers. The method comprises subjecting
one or more polyamide-forming monomers to a polymerization pro-
CA 02323360 2000-09-OS
WO 99/46323 PC'T/EP99/00889
3
cess in the presence of an effective amount of at least one hin-
dered piperidine compound and an effective amount at least one
aliphatic, dicarboxylic acid chain regulating compound.
In another aspect, the present invention is directed to a light
and thermally stable polyamide comprising a backbone polymer
chain, at least one hindered piperidine radical, and at least one
aliphatic, dicarboxylic acid chain regulating compound wherein
the at least one hindered piperidine radical and the at least one
aliphatic, dicarboxylic acid chain regulating compound are
chemically bonded to the backbone polymer chain. The polyamide of
the present invention is substantially free from copper
compounds.
The modified polyamide with built-in stabilizers made according
to the present invention achieves good light and heat stability
without the use of other stabilizers such as, for example, copper
salts. The combination of at least one aliphatic, dicarboxylic
acid chain regulating compound and at least one hindered
piperidine compound not only functions as a molecular weight re-
gulator in the polymerization process, but also endows the resul-
ting polyamide with light and heat stability. The modified poly-
amide of the present invention does not discolor in the early
stage of ultraviolet exposure.
2s
The above and other objects, effects, features, and advantages of
the present invention will become more apparent from the follo-
wing detailed description of the preferred embodiments thereof,
particularly when viewed in conjunction with the accompanying fi-
gures.
FIG. 1 is a graph illustrating the percent strength retained for
solution-dyed yarns after exposure in a weatherometer.
FIG. 2 is a graph illustrating the yellowing of polymer plaques
after exposure in a weatherometer.
To promote an understanding of the principles of the present in-
vention, descriptions of specific embodiments of the invention
follow, and specific language is used to describe the same. It
will nevertheless be understood that no limitation of the scope
of the invention is intended by the use of this specific language
and that alterations, modifications, equivalents, and further ap-
plications of the principles of the invention discussed are con-
templated as would normally occur to one of ordinary skill in the
art to which the invention pertains.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
4
As used herein, the term "polyamide" denotes homopolymers,
copolymers, blends, and grafts of those long chain polymers ha-
ving recurring amide groups (-CO-NH-) as an integral part of the
main polymer chain. These long chain polyamides are generally re-
ferred to as "nylons."
As used herein with respect to the polyamide of this invention,
the term "built-in" means that the components that render the
polyamide light and heat stable are chemically bonded to the
backbone polymer chain of the polyamide rather than merely physi-
cally admixed with the polyamide.
In one embodiment, the present invention is a modified polyamide
substantially free of copper compounds comprising a backbone po-
lymer chain, at least one hindered piperidine radical, and at
least one aliphatic, dicarboxylic acid chain regulating compound
wherein the at least one hindered piperidine radical and the at
least one aliphatic, dicarboxylic acid chain regulating compound
are chemically bonded to the backbone polymer chain. The light
and thermally stable polyamide of the present invention may be
nylon 6, nylon 6/6, nylon 6/9, nylon 6/10, nylon 6T, nylon 6/12,
nylon 4/6, nylon 11, nylon 12, or aromatic nylons such as, for
example, poly(meta-phenylene isophthalamide) and poly(para-pheny-
lene terephthalamide). Preferably, the light and thermally stable
polyamide of this invention is nylon 6, nylon 6/6, nylon 6T, ny-
lon 6/12, and nylon 4/6. Most preferably, the light and thermally
stable polyamide of the present invention is nylon 6.
Any suitable polyamide-forming monomers may be used to form the
light and thermally stable polyamide of the present invention.
Nonlimiting examples of such suitable polyamide-forming monomers
are diamine compounds, dicarboxylic.acids, caprolactam monomers,
and combinations thereof. In a preferred embodiment of the pre-
sent invention, the polyamide-forming monomers are composed of
caprolactam monomers.
The polymerization process by which the polyamide of the present
invention is formed is preferably carried out according to con-
ventional processes such as, for example, those described in U.S.
Patent No. 5,149,758 to Matthies, the entirety of which is herein
incorporated by reference, except that the polymerization of the
present invention is carried out in the presence of an effective
amount of one or more hindered piperidine compounds and an effec-
tive amount of one or more aliphatic, dicarboxylic acid chain re-
gulating compounds. An effective amount of at least one hindered
piperidine compound is an amount sufficient in combination with
the one or more aliphatic, dicarboxylic acid chain regulating
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
compounds to render the resultant polyamide light and thermally
stable. Preferably, the effective amount of the one or more hin-
dered piperidine compounds is in the range of about 0.030 to ab-
out 0.800, and more preferably about 0.060 to about 0.400, mole
5 percent based on the weight of the polyamide-forming monomers
used. An effective amount of at least one aliphatic, dicarboxylic
acid chain regulating compound is an amount sufficient in combi-
nation with the one or more hindered piperidine compounds to ren-
der the resultant polyamide light and thermally stable. Prefera-
bly, the effective amount of the one or more aliphatic, dicarb-
oxylic chain regulating compounds is in the range of about 0.001
to about 0.800, and more preferably about 0.050 to about 0.500,
mole percent based on the weight of the polyamide-forming
monomers used.
To make the polyamide of the present invention, the one or more
hindered amine compounds and the one or more aliphatic, dicarb-
oxylic acid chain regulating compounds are added to the starting
monomers or to the polymerizing reaction mixture. Thus, the one
or more hindered piperidine compounds, the one or more aliphatic,
dicarboxylic acid chain regulating compounds, and the polyamide-
forming monomers may be added separately or as a mixture to a re-
actor in which polymerization is effected.
The hindered piperidine compound used in the present invention is
represented by the formula:
H H Rz
Rz
H
N-R 3
Ri %
R2
H H R2
wherein R1 comprises an amine- or amide-forming functional group,
Rz is an alkyl, and R3 is selected from the group consisting of
hydrogen, C1-C3 alkyl groups, and -OR4 where R4 is selected from
the group consisting of hydrogen, methyl, and C1-C7 alkyl groups.
R1 is preferably selected from the group consisting of -NHRS where
R5 is hydrogen or a C1-Ce alkyl, carboxyl, carboxylic acid deriva-
tive, -(CHz)X(NH)R5 where x is an integer of from 1 to about 6,
-(CHZ)yCOOH where y is an integer of from 1 to about 6, and
-(CHz)yCOOH acid derivative. The hindered piperidine compound used
in the present invention is preferably an amino polyalkylpiperi-
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
6
dine or a polyalkylpiperidine acid. Nonlimiting examples of such
hindered piperidine compounds include:
4-amino-2,2,6,6-tetramethylpiperidine;
4-(aminoalkyl)-2,2,6,6-tetramethylpiperidine;
4-(aminoaryl)-2,2,6,6-tetramethylpiperidine;
4-(aminoaryl/alkyl)-2,2,6,6-tetramethylpiperidine;
3-amino-2,2,6,6-tetramethylpiperidine;
3-(aminoalkyl)-2,2,6,6-tetramethylpiperidine;
3-(aminoaryl)-2,2,6,6-tetramethylpiperidine;
3-(aminoaryl/alkyl)-2,2,6,6-tetramethylpiperidine;
2,2,6,6-tetramethyl-4-piperidinecarboxylic acid;
2,2,6,6-tetramethyl-4-piperidinealkylcarboxylic acid;
2,2,6,6-tetramethyl-4-piperidinearylcarboxylic acid;
2,2,6,6-tetramethyl-4-piperidinealkyl/arylcarboxylic acid;
2,2,6,6-tetramethyl-3-piperidinecarboxylic acid;
2,2,6,6-tetramethyl-3-piperidinealkylcarboxylic acid;
2,2,6,6-tetramethyl-3-piperidinearylcarboxylic acid; and
2,2,6,6-tetramethyl-3,4-piperidinealkyl/arylcarboxylic acid.
The hindered amine compound may be a mixture of hindered
piperidine compounds as well. More preferably, the hindered
piperidine compound is a 2,2,6,6-tetraalkylpiperidine. Most pre-
ferably, the hindered piperidine compound is 4-amino-2,2,6,6-te-
tramethylpiperidine.
Suitable chain regulating compounds for use in the present inven-
tion are aliphatic, dicarboxylic acids and combinations thereof.
Non-limiting examples of such aliphatic, dicarboxylic acids inc-
lude the following:
malic acid;
malonic acid;
methylmalonic acid;
ethylmalonic acid;
butylmalonic acid;
dimethylmalonic acid,
succinic acid;
methylsuccinic acid;
2,2-dimethylsuccinic acid;
2,3-dimethylsuccinic acid;
2-ethyl-2-methylsuccinic acid;
glutaric acid;
2,2-dimethylglutaric acid;
2,3-dimethylglutaric acid;
2,4-dimethylglutaric acid;
adipic acid;
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
7
3-methyladipic acid;
azelaic acid;
pimelic acid;
sebacic acid;
decanedicarboxylic acid; and
dodecanedioic acid.
The aliphatic, dicarboxylic acid chain regulating compound used
in the present invention may be the same or different from a
dicarboxylic acid that is used as a polyamide-forming compound.
The aliphatic, dicarboxylic acid chain regulating compound is
preferably selected from the group consisting of C4-Clo alkane
dicarboxylic acids, particularly adipic acid, azelaic acid, seba-
cic acid, and decanedicarboxylic acid. Most preferably, the
aliphatic, dicarboxylic acid chain regulating compound is adipic
acid.
Of course, various non-stabilizing additives may be used in the
modified polyamide of the present invention. These include, for
example and without limitation, lubricants, nucleating agents,
antioxidants, antistatic agents, etc.
The present invention produces a modified polyamide that is sta-
bilized from degradation by light and heat and that does not di-
scolor, i.e., yellow, upon exposure to light and/or heat. With
the present invention, it is not necessary to use other stabili-
zers such as, for example, copper compounds, as additives, alt-
hough other stabilizers may be present, if desired. If such other
stabilizers are present, they are present in significantly redu-
ced amounts. The elimination of such stabilizing additives redu-
ces equipment maintenance costs and eliminates harmful effluents
produced in the removal of stabilizer deposits.
The present invention also produces a modified polyamide having
increased spinning efficiency. Spinning efficiency is increased
by at least about 0.5 percent. Such increase in spinning effi-
ciency translates into hundreds of thousands of dollars in redu-
ced annual manufacturing costs. While not wishing to be bound by
any theory, it is currently believed that the increased spinning
efficiency results from that fact that the modified polyamide of
the present invention has a narrower molecular weight distribu-
tion than acetic acid- and propionic acid-regulated polyamides.
For polymers having a relative viscosity of 2.7, the molecular
weight distribution of the modified polyamide of the present in-
vention is about 1.65 to about 1.80, and the molecular weight
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
8
distribution of acetic acid- and propionic acid-regulated poly-
amides is about 1.90 to about 2.00.
The present invention is further directed to articles produced
from the light and thermally stable polyamide of the present in
vention and to methods of producing such articles. Non-limiting
examples of such articles include fibers, yarns, carpets, engi-
neering plastics such as automotive parts, and the like. Fibers
may be formed by subjecting the light and thermally stable poly-
amides of the present invention to any conventional fiber-forming
process such as, for example, that disclosed in U.S. Patents Nos.
4,983,448 to Karageorgiou and 5,487,860 to Kent et al., the ent-
irety of both of which are incorporated herein by reference. Pre-
ferably, the fiber-forming process involves rapidly spinning the
light and thermally stable polyamide at take-off speeds of at
least about 4,000 m/min. Engineering plastics may be formed by
subjecting the light and thermally stable polyamides of the pre-
sent invention to any conventional plastic-forming process such
as, for example, that disclosed in U.S. Patent No. 5,474,853 to
Watanabe et al., the entirety of which is incorporated herein by
ref erence .
Fibers formed from the light and thermally stable polyamides of
the present invention may be dyed with conventional dyes used to
dye nylons such as, for example, metalized and non-metalized acid
dyes. Usual dyebath conditions for dyeing nylon can be employed.
The following general conditions are exemplary and not intended
to be limiting. A dyebath is prepared at a volume equal to about
20 times the weight of the articles to be dyed. Processing
chemicals are added including a chelating agent to prevent the
deposition or complexing of metal ions in hard water, a dye leve-
ling agent, and, in the case of metalized acid dyes, an acid
donor to slowly lower the dyebath pH. The dyestuff is added, and
the dyebath pH is adjusted. The solution is heated to the desired
temperature of typically about from 95°C to about 110°C at a
rate
of from about 0.5°C to about 3.0°C per minute and is held at
that
temperature for about 30 minutes to about 60 minutes. The dyebath
is cooled or emptied, and the articles are thoroughly rinsed with
fresh water. The dyed articles are dried in a tumble drier or an
oven such as a Tenter oven.
Alternatively, fibers made from the light and thermally stable
polyamides of the present invention may be solution-dyed before
being formed into articles. Usual conditions for solution-dyeing
nylon can be employed. The following general conditions are exem-
plary and not intended to be limiting. The polyamide of the pre-
sent invention is melted and colored with a colorant selected
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
9
from the group consisting of pigments, dyes, any colored compound
with properties between pigments and dyes, and combinations the-
reof. The colored polyamide is then spun into fibers or fabric
according to conventional methods such as, for example, those
disclosed in U.S. Patent No. 4,983,448 to Karageorgiou, U.S. Pa-
tent No. 5,487,860 to Kent et al., and U.S. Patent No. 4,918,947
to Speich. For engineering plastics, polymer chips are mixed with
colored compounds such as, for example, pigments and dyes, before
charging into an extruder. The mixing before being charged into
the extruder is a physical mix, not a melt mix.
The invention will be further described by reference to the fol-
lowing detailed examples. The examples are set forth by way of
illustration and are not intended to limit the scope of the in-
vention. In the examples, "ADA" refers to adipic acid, "PPA" re-
f ers to propionic acid, "TPA" refers to terephthalic acid, and
"TAD" refers to 4-amino-2,2,6,6-tetramethylpiperidine. Also as
used in the examples, the following terms and test conditions are
defined as follows:
ao
Weight Percent.
The weight percentage of that component in the charge.
Relative Viscosity (RV).
The relative viscosity compares the viscosity of a solution of
polymer in formic acid with the viscosity of the formic acid it-
self (ASTM D 789). The test results reported herein were obtained
using 0.20 g of nylon 6 dissolved in 20 cc. of formic acid at
25°C.
End Group Content.
The amino end group content is determined by dissolving about 2.0
g of the polymer in about 60 cc. of a phenol-methanol mixture
(68:32). This solution is titrated with about 0.20 normal HC1 at
about 25°C by a potentiometric method, wherein the endpoint is de-
termined by a steep potential increase.
The carboxy end group content is determined by dissolving about
0.30 g of the polymer in about 40 cc. of a mixture of benzyl al-
cohol at 180°C. The solution is titrated with about 0.03 normal
t-butyl ammonium hydroxide at about 80°C to about 100°C by a po-
tentiometric method, wherein the endpoint is determined by a
steep potential increase.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
Exposure Test.
This test is designed to simulate extreme environmental condi-
tions encountered inside a vehicle due to sunlight, heat, and hu-
5 midity for the purpose of predicting the performance of auto-
motive interior trim materials. This test measures the amount of
yellowing (the delta b* value) of each of the exposed samples.
This test is performed in accordance with the GM SAE J1885 Test
Method, which is entitled "Accelerated Exposure of Automotive In-
10 terior Trim Components using a Controlled Irradiance Water-Cooled
Xenon-Arc Apparatus."
Strength Retention.
This test is designed to determine the strength retention of the
controls and the experimental samples. The term "strength reten-
tion" ref ers to the change in tenacity of the material as a re-
sult of exposure of the material to sunlight or an artificial
light source. The tenacity is a measure of fiber strength. This
test is performed in accordance with the AATCC Test Method
16-1993, Colorfastness to Light, Option E (Water-Cooled Xenon-Arc
Lamp, Continuous Light). The materials are exposed for 2125 kJ of
exposure, and the tenacity of each material is measured before
exposure and after each 425 kJ increment of exposure. Percent
strength retention is determined as follows:
Tenaci after ex op sure x 100%
Tenacity before exposure
EXAMPLE 1 (Comparative)
Polymerization of PPA/TAD-Regulated Nylon 6
A mixture of 75 kg of caprolactam, 1800 g of water, 135 g (0.18
weight percent) propionic acid, and 112.5 g (0.15 weight percent)
4-amino-2,2,6,6-tetramethylpiperidine is charged into a 250-liter
autoclave. The mixture is heated to 270°C in one hour, while the
pressure increases to 60 psi (3102 mm Hg). After holding the mix-
ture at 60 psi for 30 minutes, the pressure is slowly released.
To accelerate the polymerization, the system is placed under a
vacuum of 400 mm Hg for 75 minutes. The polymer is then extruded
under a positive nitrogen pressure and cut into chips. The chips
are washed with hot water (90°C) and dried in a tumble dryer. The
relative viscosity measures 2.71. The amino group content measu-
res 42 meq/kg, and the carboxylic end group content measures 45
meq/kg.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
11
EXAMPLE 2
Polymerization of ADA/TAD-Regulated Nylon 6
A mixture of 75 kg of caprolactam, 1800 g of water, 240 g (0.32
weight percent) adipic acid, and 112.5 g (0.15 weight percent)
4-amino-2,2,6,6-tetramethylpiperidine is charged into a 250-liter
autoclave. The mixture is heated to 270°C in one hour, while the
pressure increases to 60 psi (3102 mm Hg). After holding the mix-
ture at 60 psi for 30 minutes, the pressure is slowly released.
To accelerate the polymerization, the system is placed under a
vacuum of 500 mm Hg for 45 minutes. The polymer is then extruded
under a positive nitrogen pressure and cut into chips. The chips
are washed with hot water (90°C) and dried in a tumble dryer. The
relative viscosity measures 2.67. The amino group content measu-
res 37 meq/kg, and the carboxylic end group content measures 70
meq/kg.
EXAMPLE 3 (Comparative)
Polymerization of PPA/0.15~5 TAD-Regulated Nylon 6
A mixture of molten caprolactam containing 0.5 by weight water
and 0.19 by weight propionic acid is continuously introduced into
the top of a polymerization reactor. The polymerization reactor
used is a stainless steel VK column as outlined in U.S. Patent
No. 4,354,020, which is incorporated herein by reference. The
mixture is continuously introduced into the top of the VK column
into reaction zone I at a temperature of about 265°C and at a rate
of about 30-40 kg/h with stirring. The VK column, which has a ca-
pacity of 340 liters, is heated by heat exchange oil. At the same
time, 4-amino-2,2,6,6-tetramethylpiperidine is continuously sup-
plied from a separate stream to the reaction zone I at a rate so
that there is 0.15 weight percent of 4-amino-2,2,6,6-tetramethyl-
piperidine in the mixture at all times. The heat of
polymerization generated in further reaction zones is removed by
appropriate cooling with internal heat exchangers. The
temperature of the last reaction zone is about 265°C. The resul-
ting polymer is extruded at the bottom of the VK column and cut
into chips. The chips are washed with hot water (90°C) and dried
in a tumble dryer. The relative viscosity measures 2.68. Both the
amino group content and the carboxylic end group content measure
44 meq/kg.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
12
EXAMPLE 4
Polymerization of ADA/0.15~ TAD-Regulated Nylon 6
Caprolactam is polymerized in the same VK column as in Example 3,
but with the addition of 0.29 weight percent adipic acid, 0.5
weight percent water, and 0.15 weight percent 4-amino-2,2,6,6-te-
tramethylpiperidine. The dried product has a relative viscosity
of 2.73, an amino end group content of 43 meq/kg, and a
carboxylic end group content of 59 meq/kg.
EXAMPLE 5
Polymerization of ADA/0.30~ TAD-Regulated Nylon 6
Caprolactam is polymerized in the same VK column as in Example 3,
but with the addition of 0.29 weight percent adipic acid, 0.5
weight percent water, and 0.30 weight percent 4-amino-2,2,6,6-te-
tramethylpiperidine. The dried product has a relative viscosity
of 2.70, an amino end group content of 53 meq/kg, and a
carboxylic end group content of 51 meq/kg.
EXAMPLE 6 (Comparative)
Polymerization of TPA/0.15~ TAD-Regulated Nylon 6
Caprolactam was polymerized in the same VK column as in Example 3
with addition of 0.30 weight percent terephthalic acid, 0.5
weight percent water, and 0.15 weight percent 4-amino-2,2,6,6-te-
tramethylpiperidine. The dried product had a relative viscosity
of 2.68, an amino end group content of 42 meq/kg, and a
carboxylic end group content of 63 meq/kg.
EXAMPLE 7
Spinning of 1115 Denier/58 Filament Solution-Dyed Yarn with Tri-
lobal Cross-Section
Nylon 6 polymer from Examples 3-6, as well as commercial nylon 6
(Ultramid B~ nylon 6 available from BASF Corporation of Mount
Olive, NJ), is extruded at 260°C-265°C. Opal gray color
concen-
trate mixed with a proper amount of nylon chip is added to the
spinning machine through volumetric feeders. The extruded fila-
ments are cooled and solidified by a stream of quench air at 15°C.
After the application of spin finish, the yarns are drawn at a
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
13
draw ratio of 3.3 and are textured in a texture jet at 215°C. The
yarns are taken up at a draw roll speed of about 2350 m/min.
EXAMPLE 8
Strength Retention after Ultraviolet Exposure
Opal gray solution-dyed yarns from Example 7 are exposed in an
Atlas Ci65 Weather-Ometer~ for 2125 kJ exposure in increments of
425 kJ under the conditions specified by the AATCC Test Method
16-1993, Colorfastness to Light, Option E. The strength of each
of the yarns is measured before exposure and after each 425 kJ
increment of exposure. The percent strength retention after each
increment of exposure is shown in FIG. 1. These results show a
significant improvement in retained strength for the TAD-contai-
ning polymers, especially the ADA/TAD polymers. The commercial
nylon 6 lost its strength dramatically during the exposure, while
the TAD-containing polymers retained more than 85~ of their
strength after 2125 kJ of exposure.
ao
EXAMPLE 9
Yellowing of Plaques by GM SAE J1885 Test Method
Polymer from Examples 3-6, as well as commercial nylon 6
(Ultramid B~ nylon 6 available from BASF Corporation of Mount
Olive, NJ), is melted in an injection molding machine at about
265°C. The molten polymer is injected into a mold to make 110mm x
110mm x 3mm plaques. These plaques are then cut into smaller pla-
ques, each measuring about 55mm x 110mm x 3mm.
The plaques are then exposed in an Atlas Ci65 Xenon-Arc Weather-
Ometer~ for 1,000 hours (1,410 kJ) in 100 hour (141 kJ) incre-
ments by the conditions specified in the GM SAE J1885 Test
Method. The exposed plaques are measured for yellowing (or "Delta
b*," where a higher Delta b* value indicates a more yellow sam-
ple) at each increment of exposure using an Applied Color Systems
Spectrophotometer. The results of these exposures are plotted in
FIG. 2. The results show that the commercial nylon 6 polymer and
the comparative TPA/0.15~ TAD-regulated polymer yellowed most si-
gnificantly during the exposure. While exposure of the PPA/TAD
polymer resulted in less yellowing than the commercial nylon 6
polymer and the comparative TPA/0.15~ TAD-regulated polymer, ex-
posure of the ADA/TAD polymers resulted only in minimal yello-
wing.
CA 02323360 2000-09-OS
WO 99/46323 PCT/EP99/00889
14
While the invention has been described in connection with what is
presently considered to be the most practical and preferred embo-
diment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is in-
s tended to cover various modifications and equivalents arrange-
ments included within the spirit and scope of the appended
claims.
15
25
35
45
