Note: Descriptions are shown in the official language in which they were submitted.
C-14-54-0221
~063294
POLYAMIDES DERIVED FROM HEXAMETHYLENE DIAMINE,
TEREPHTHALIC ACID, ISOPHTHALIC ACID AND A
Cs TO Clo ALIPHATIC DIBASIC ACID
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to fiber-forming random
copolyamides prepared by melt polymerization of the
hexamethylene diamine salts of certain aromatic and aliphatic
dibasic acids. Annealed fibers made from copolyamides of
the invention have exceptional properties such as dimensional
stability and are useful in industrial and textile fiber
applioations.
As used herein, the term "fiber" means continuous
filament yarns, monofilaments, tows and spinnable staples;
the term "6TA units" refers to units of the formula
1 f~
-NH-~-CH2 ~ NH-C ~ C-; the term "6IA units" refers to
O O
units of the formula -NH-~-CH2-~-6NH-C ~ C-; the term
"6RA units" refers to units of the formula
O O
-NH-~-CH2-~-6NH-C-R-C-, where R is a C3 to C10 alkylene; the
term "66 units" refers to 6RA units where R is -~-CH2 ~ ;
the term "6TA/6IA polymer" means a random copolymer consisting
of recurring 6TA and 6IA units of which from 50 to 80 mole %
of the units are 6TA units; and the term "6TA/6IA/6RA polymer"
means a random copolymer consisting essentially of 6TA, 6IA
and 6RA units.
-2-
C-14-54-0221
~063294
2. Description of the prior art
British Patent 1,382,551 describes the preparation
of dimensionally stable fibers of 6TA/6IA polymers by a
batch process wherein an aqueous solution o the hexamethylene
diamine salts of terephthalic and isophthalic acids (6TA
and 6IA salts) is heated in an autoclave under conditions
of controlled time, temperature and pressure to provide
molten 6TA/6IA polymer which is then extruded directly from
the base of the autoclave into fibers. The fibers are
essentially amorphous and are drawn and annealed to increase
the crystallinity and enhance the tensile properties thereof.
A small amount of the 6TA/6IA polymer remains as a shell on
the inner wall and agitator of the autoclave after extrusion.
Unfortunately, the 6TA/6IA polymer shell does not entirely
melt during the next polymerization. Particles of the
6TA/6IA polymer shell disperse in the molten 6TA/6IA polymer
formed in the next polymerization to yield a heterogeneous
6TA/6IA polymer, a condition referred to herein as "polymer
heterogeneity". Attempts to provide useful fibers by the
melt spinning of heterogeneous 6TA/6IA polymer has not been
entirely successful and in some instances fibers cannot be
obtained at all. In those instances where fibers are obtained,
the fibers are opaque in appearance, contain particles of
noticeable size, and generally have unacceptable properties.
Therefore, to obtain high quality fibers it is necessary to
clean the autoclave between each run (i.e. polymerization
and extrusion) to remove the 6TA/6IA polymer shell that
remains therein after extrusion. Cleaning of the autoclave
after each run is time consuming and costly and, therefore,
` C-14-54-0221
1063Z94
is not feasible for commercial operations.
An object of the present invention is to provide a
modified, fiber-forming 6TA/6IA polymer composition which can
be prepared by a batch process in an autoclave without
encountering polymer heterogeneity and without cleaning the
autoclave between successive runs to remove the polymer shell
therefrom.
Another object of the invention is to provide a
modified 6TA/6IA polymer composition from which useful fibers
can be shaped.
SUMMARY OF THE INVENTION
In accordance with the present invention melt
polymerization of 6TA and 6IA salts is carried out in the
presence of one or more hexamethylene diamine salts of an
O ~
aliphatic dibasic acid of the formula HO-C-R-C-OH, wherein
R is an alkylene having from 3 to 10 carbon atoms, to provide
a copolyamide consisting essentially of recurring units of
the formulas:
O O
Il /=\ 11
(A) -NH t CH2 -t~ NH-C ~ C-
O O
(B) -NH -~ CH2 ~ NH-C ~ C-
1l 1l
(C) -NH -1~ CH2 -~-6 NH-C-R-C-
wherein R is a C3 to Clo alkylene and is the same or different
in successive (C) units; and from 30 to 40 percent of the
recurring units are (B~ units, from 2-15 percent of the
C-14-54-0221
1063294
recurring units are (C) units, and the remainder of the
recurring units are (A) units.
Copolyamides of the invention can be prepared by a
batch process in an autoclave and extruded therefrom without
encountering polymer heterogeneity and without cleaning the
autoclave between successive runs to remove the polymer
shell therefrom.
As-spun fibers prepared from copolyamides of the
invention normally are essentially amorphous and can be
annealed according to annealing procedures described in the
above mentioned British Patent to increase the crystallinity
thereof. The annealing may be accomplished either during or
after the as-spun fibers are drawn (i.e., stretched) to a
desired orientation and denier. While drawing of the as-spun
fibers result in orientation of the polymer molecules in the
direction of the axis of the fibers, drawing without annealing
does not significantly increase the crystallinity of the as-
spun fibers. Crystalline fibers prepared from 6TA/6IA/6RA
polymers of the invention have boiling water shrinkage
values of less than about 10% and combine many of the best
properties of both nylon 66 and PET (polyethylene terephthalate)
fibers. For example, the crystalline fibers have adhesion-
to-rubber and dye performance properties comparable to nylon
66 fibers and moduli and wrinkle resistance properties
comparable to PET fibers.
C-14-54-0~21
1063Z94
DETAILED DESCRIPTION OF THE PRE~%RRED EMBODIMENTS
OF THE INVENTION
6TA/6IA/6RA polymers of the invention can be
prepared by melt polymerization of a salt mixture consisting
of appropriate amounts of 6TA salt, 6IA salt and 6RA salt
wherein an aqueous solution of the salt mixture is heated in
an autoclave in a conventional manner under controlled
conditions of time, temperature and pressure. Preferably,
the polymerization is conducted in three cycles. During the
first cycle the reaction mixture is heated in the presence
of an inert gas such as nitrogen from room temperature to
about 200C. while under pressure of about 250 psig (18 atm).
During the second cycle the reaction mixture is heated to
about 300C. while holding the pressure substantially
constant. During the third cycle the temperature is increased
slightly, for example, an additional 10 to 20C. while the
pressure is reduced to atmospheric pressure. Optionally,
after completion of the third cycle the resulting molten mass
is held at atmospheric pressure at or above the melting
temperature thereof for a period of time sufficient to bring
the molten mass to equilibrium, for example, 30 minutes. The
optimum time, temperature and pressures involved in
conducting each of the polymerization cycles will vary some-
what depending on the melting point of the particular
6TA/6IA/6RA polymer being prepared. The resulting molten
6TA/6IA/6RA polymer can be extruded through a spinneret
attached to the base of the autoclave to obtain essentially
amorphous fibers. Successive runs can be made in the auto-
clave without removing the polymer shell from the autoclave
between runs and without encountering polymer heterogenity.
C-14-54-0221
1063294
The resulting fibers are then drawn and annealed to increase
the crystallinity and otherwise to enhance the physical
properties thereof.
The annealing of the essentially amorphous fiber
may be accomplished during or after the fiber is drawn to a
desired denier. Generally, the fiber is drawn a total of 3.0
to 5.0 times its original length. When the fiber is drawn
prior to annealing, it may be drawn in a single stage over a
heated pin t85-115C.). Drawing of the essentially amorphous
fiber without annealing results in orientation o, the polymer
molecules in the direction of the fiber axis but does not
significantly increase the crystallinity of the fibers. How-
ever, after the drawn, essentially amorphous fiber is annealed
in the manner described herein, the fiber has a relatively
high degree of crystallinity. Annealing of the fiber is con-
veniently accomplished by heating the fiber to a temperature
which is above the glass transition temperature (Tg) of the
polymer and below the temperature at which the fiber becomes
molten and, preferably, at a temperature above about 160C.
Annealing of the fiber may be accomplished by subjecting the
fiber to a heated environment, such as a heated inert fluid
(e.g., steam, air or nitrogen) or a heated surface such as a
hot shoe. A preferred means for heating the fiber is
accomplished by continuously advancing the fiber through an
electrically heated tube blanketed with steam or heated
nitrogen. Other means include continuously advancing
the fiber through a chamber equipped with an infrared heater
or over a heated curved surface. If desired, the fiber
may be merely placed in an oven and heated. The length of
time the fiber is in contact with the heated environment
C-14-54-0221
1063Z94
will depend on factors such as the temperature of the heated
environment and denier of .he fiber. Various means and
conditions that may be used in annealing fibers of the
invention will be apparent to those skilled in the art.
It has been found that the physical properties of
the annealed fibers are influenced by the amount of tension
the fibers are under while being annealed. For example,
drawn fibers which are slack when annealed will have minimum
boiling water shrinkage (BWS) values, for example lower than
2%, while drawn fibers which are under considerable tension
when annealed (e.g., when further drawn at a draw ratio of
1.12 to 1.2 during annealing) generally will have BWS values
between 8% and 10%. Accordingly, drawn fibers which are under
intermediate tensions when annealed will have BWS values
ranging from 2% to 8%. The strength of the fibers on the
other hand is directly proportional to the amount of tension
the fibers are under during annealing. Fibers which are
under tension when annealed will have greater strength than
fibers which are slack when annealed.
Salt mixtures useful in preparing 6TA/6IA/6RA
polymers of the invention consist of from 30 to 40 mole %
of 6IA salt and from 2 to 15 mole % of 6RA salt with the
remainder thereof consisting of 6TA salt. The molar
amounts of 6TA, 6IA and 6RA units in the resulting polymers
correspond to the respective molar amounts of 6TA, 6IA
and 6RA salts employed in their preparation.
C-14-54-0221
1063Z94
In order to eliminate polymer heterogeneity
effectively, at least about 2 mole % of the salt mixture
must consist of 6RA salt. On the other hand, if more than
about 15 mole % of the salt mixture consists of 6RA salt,
the boiling water shrinkage values and tensile properties
of fibers prepared from the resulting polymers are
adversely affected. Satisfactory results are generally
obtained when from 7 to 12 mole % of the salt mixture
used in preparing polymers of the invention consists of
6RA salt. In general, if more than about 40 mole % of the
salt mixture consists of 6IA salt, fibers prepared from the
resulting polymers are difficult to crystallize, whereas
if less than about 30 mole % of the salt mixture consists
of 6IA salt, it is difficult to shape fibers from the
resulting polymer due to the high melting point of the
resulting polymer.
6RA salts useful in preparing copolyamides of the
invention include the hexamethylene diamine salts of glutaric,
adipic, azelaic, suberic, sebacic or dodecanedioic acids. If
desired, a mixture of two or more 6~A salts may be used.
Hexamethylenediammonium adipate (66 salt) is a preferred 6RA
salt for use in preparing polymers of the invention.
The salts used in preparing polymers of the
invention should be of the 'nighest possible purity and may be
made by conventional techniques commonly employed in making
simple polyamide salts, for example, hexamethylene diammonium
adipate (66 salt).
The following examples are given for purposes of
further illustrating the invention and are not intended to in
any way limit the scope of the invention.
- 1063294
Tensile properties of fibers given in the examples
were measured on a tester marketed under the trade mark
"INSTRON". IntrinsiC viscosities [~] given in the examples
are defined by the following equation:
[~] = ~2(RV-l-lnRV) , where RV represents the
C
relative viscosity and C represents a concentration of 0.4
gram of the polymer in 100 ml. of solvent. The relative
viscosity is determined by dividing the flow time in a
capillary viscometer of a dilute solution of the polymer by
the flow time for pure solvent. The dilute solutions used
herein for determining RV are of the concentration expressed
by (C) above; flow times are determined at 25C. using 95%-98%
concentrated sulfuric acid as the solvent. Percent boiling
water shrinkage (% BWS) values given in the examples were
determined by the following procedure. Two clamps are secured
along a length of fiber (Ll) so that the distance between the
clamps when the fiber is extended is between 15 and 50 cm.
The fiber with the clamps secured thereto is then immersed
in boiling water for 10 minutes. The fiber is then removed
and dried under ambient conditions. The distance between the
clamps when the fiber is extended is again measured (L2).
The % boiling water shrinkage (BWS) is determined by the
following equation:
% BWS = ( Ll-L2 ) x 100
Ll
EXAMPLE 1
This example illustrates the preparation of 6TA/
6IA/66 (60/35/5) polymer, i.e. ~6TA/6IA/6RA polymer consist-
ing of 60 mole% of 6TA units, 35 mole % of 6IA units and 5
mole % of 66 units, and the melt spinning thereof into yarn.
--10--
C-14-54-0221
1063Z94
90.0 g. (0.3188 mole) of 6TA salt, 52.5 g. (0.1859 mole) of
6IA salt, 7.0 g. (0.0267 mole) 66 salt, and 100 g. of
deionized water were charged to a stainless steel autoclave.
After thoroughly purging the autoclave and its contents with
nitrogen, the autoclave was pressurized to 250 psiR (18 atm)
with nitrogen. The autoclave was then heated to 220C. over
a period of 25 minutes while stirring and maintaining the
pressure constant at 250 psig. The temperature was then
increased to 300C. over a period of 27 minutes while
maintaining the pressure at 250 psig. The pressure was then
reduced to atmospheric over a period of 25 minutes while
increasing the temperature to 316C. A 14-hole spinneret
was then attached to the base of the autoclave and the polymer
( [n] ) = O . 824) was extruded through the spinneret by the
application of 250 psig (18 atm) nitrogen. The resulting yarn
was collected on a bobbin using a conventional winder. The
yarn was then drawn 3.60X over a 2" pin at 100C. to provide
an 80 denier yarn having an elongation of 18% and a tenacity
of 3.8 gpd.
EXAMPLE 2
This example illustrates the preparation of
6TA/6IA/66(60/30/10) polymer ([n]) = 0.81) and the melt
spinning thereof into yarn. The polymer and yarn were
prepared according to the procedure of example 1. In this
instance the polymer was prepared from a mixture of 6TA,
6IA and 66 salts in which the salts were present in a molar
ratio of 60:30:10, respectively. The yarn was collected
and then drawn 3.70 times to a denier of 80. The drawn yarn
had an elongation of 18VL and a tenacity of 3.7 gpd.
C-14-54-0221
1063294
EXAMPLE 3
This example illustrates the preparation of
6TA/6IA/66(55/35/10) polymer ([n]) = 0.80) and the melt
spinning thereof into yarn. The polymer and yarn were prepared
according to the procedure of example 1. In this instance
the polymer was prepared from a mixture of 6TA, 6IA and 66
salts in which the salts were present in a molar ratio of
55:35:10, respectively. The yarn was collected and then
drawn 3.95 times to a denier of 71. The drawn yarn had an
elongation of 16% and a tenacity of 3.7 gpd.
EXAMPLE 4
This example illustrates the preParation of
6TA/6IA/66(50/35/15) Polymer and the melt s~innin~ thereof
into yarn. The polymer and yarn were prepared according to
the procedure of example 1. In this instance the polymer
was prepared from a mixture of 6TA, 6IA and 66 salts in which
the salts were Present in mole ratio of 50:35:15, respectively.
The yarn was collected and then drawn 3.80 times to a denier
of 74. The drawn yarn had an elongation of 20% and a tenacity
of 2.8 gpd.
EXAMPLE 5
A sample of each of the yarns of examples 2-4 was
annealed by continuously advancing the yarn at constant length
(draw ratio of 1.0) and at a speed of 125 feet (38.1 meters)
per minute through a chamber ha~ing a length of 30.5 cm and
containing infra-red heaters. The chamber was maintained at a
temperature of about 300C. For purposes of comparison a 70
denier, 14 filament yarn prepared from 6TA/6IA(65/35) was
also annealed under the same conditions. The % BWS of each of
the yarns was determined before and after annealing and is
given in Table I.
-12-
~-14-54-0~1
1063Z94
TABLE I
Molar Composition % BWS
6TA/6IA/66 Before Annealin~After Annealing
65/35/0 2~.0 6.6
60/30/10 22.2 5.6
55/35/10 21.9 8.7
50/35/15 38.7 9.5
The results in Table I show that yarns made from
polymers of the present invention may be annealed to provide
dimensionally stable yarns which are comparable to annealed
yarns of 6TA/6IA polymer.
EXAMPLE 6
This example illustrates that fibers of polymers of
the present invention can be made by a batch process in an
autoclave without cleaning the autoclave between successive
runs to remove the polymer shell from the autoclave and
without encountering polymer heterogeneity. In the batch
process two successive runs were made without cleaning the
autoclave after the first run. In each run a mixture of 6TA,
6IA and 66 salts were polymerized in the autoclave to form
molten polymer. The molten polymer was then extruded from
the base of the autoclave into water, recovered and, where
possible, melt spun into yarn.
6TA/6IA/66(55/35/10) polymer was prepared by
charging 825 g. (2.922 mole) of 6TA salt, 525 g. (1.859 mole)
of 6IA salt> 140 g. (0.534 mole) of 66 salt, and 1000 g. H20
to a clean autoclave. After purging thoroughly with
purified nitrogen, the autoclave was sealed and heated to
200C. while stirring and allowing the pressure to increase
to 200 psig (14.6 atm). The temperature and pressure were
-13-
C-14-54-0221
1063Z94
then held constant for 15 minutes. The temperature was then
increased to 218C. over a period of 3 minutes while allowing
the pressure to increase to 250 psig (18 atm) and remain
constant. The temperature was then raised to 300~. (250
psig or 18 atm) over a period of 30 minutes. The pressure
was then reduced to atmospheric pressure over a period of 65
minutes while increasing the melt temperature to 320C. The
polymer was then extruded from the autoclave and quenched in
water. The extruded polymeric mass was clean and
homogeneous. Following extrusion about 150 g. of polymer were
left in the clave as a shell on the walls and agitator. A
second polymerization was then carried out in the autoclave
in the presence of the polymer shell using substantially the
same procedure and conditions that were used in the first
polymerization. The extruded polymeric mass was clear,
homogeneous and easily melt spun into yarn. After the second
polymerization about 145 g. of polymer remained in the auto-
clave after extrusion.
For purposes of comparison 6TA/6IA(65/35) polymer
was prepared by charging 975 g. (3.453 mole) of 6TA salt,
525 g. (1.859 mole) of 6IA salt, and 1000 g. H20 to a clean
autoclave. Polymerization was accomplished using substantially
the same procedure and conditions that were used above.
About 145 g. of polymer remained in the autoclave after
extrusion. A second polymerization was then carried out in the
autoclave in the presence of the polymer shell using
substantially the same procedure and conditions that were
used in the first polymerization. The resulting extruded
polymeric mass contained lumps of white, opaque material
dispersed in a clear polymer matrix, i.e. the polymeric
-14-
C-14-54-0221
1063Z94
mass was heterogeneous. The heterogeneities prevented melt
spinning of the polymer into the yarn.
The foregoing examples illustrate that the
modified 6TA/6IA polymers of the invention can be made without
encountering polymer heterogeneity and can be melt spun into
fibers which, when annealed, have substantially the same
properties as annealed 6TA/6IA fibers. An important
advantage of the polymers of the invention over 6TA/6IA
polymers is that polymers of the invention can be prepared in
a batch autoclave without cleaning the autoclave after each
run. In contrast, in preparing 6TA/6IA polymers in a batch
autoclave the autoclave must be cleaned after each run to
prevent polymer heterogeneity. Cleaning of the autoclave
after each run is time consuming and costly and cannot be
tolerated in commercial operations.
While the foregoing examples illustrate polymers
prepared from 6TA, 6IA and 66 salts, similar results will
also be obtained when the 66 salt is replaced with an
equivalent molar amount of another hexamethylene diamine salt
of a Cs to C12 dicarboxylic acid, for example, glutaric,
suberic or dodecanedioic acids, or mixtures thereof.
-15-
