PROCEDE DE FABRICATION DE FIBRES A DENIER ELEVE COMPOSEES DE CRISTAUX LIQUIDES POLYMERIQUES THERMOTROPIQUES ET COMPOSITIONS DE CES PRODUITS

PROCESS FOR MAKING HIGH DENIER FILAMENTS OF THERMOTROPIC LIQUID CRYSTALLINE POLYMERS AND COMPOSITIONS THEREOF

Abrégé anglais

The present invention discloses and claims a novel process for the formation
of
high denier as-spun and heat-treated filaments of a thermotropic liquid
crystalline
polymer. Preferred embodiments include process for the formation of as-spun
and heat
treated monofilaments of a few wholly aromatic polyesters and polyesteramides.
The
process involves (a) heating of a thermotropic liquid crystalline polymer to
above its
melting transition temperature; (b) passing said molten polymer through an
extrusion
chamber equipped with an extrusion capillary of an aspect ratio of greater
than about 1
and less than about 15 to form a filament; and (c) winding the filament at a
draw-down
ratio of at least about 4. The filaments so formed are of at least 50 denier
per filament
(dpf) and feature essentially uniform molecular orientation across the cross-
section. In
a final optional step, the filaments are heat treated in stages to form
filaments
exhibiting excellent tensile properties. Both as-spun and heat-treated
filaments feature
remarkably good tensile properties retaining at least 80 to 90 percent of the
properties
expected of conventional low denier (5 to 10 dpf) filaments.

Revendications

1. A process for forming an as-spun filament of a thermotropic liquid
crystalline
polymer having the following properties:
(i) denier of at least about 50 denier per filament;
(ii) tenacity of at least about 8 grams per denier;
(iii) modulus of at least about 450 grams per denier; and
(iv) elongation of at least about 2 percent;
said process comprising the steps of:
(a) heating a thermotropic liquid crystalline polymer to a temperature of at
least about 15 °C above its melting transition to form a fluid stream
of
said thermotropic polymer;
(b) passing said stream through a heated extrusion chamber, wherein said
chamber is disposed with a suitable cylindrical orifice to form the
filament of said polymer, and wherein said cylindrical orifice has an
aspect ratio of length to diameter (L/D) greater than about 1 and less
than about 15; and
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down (DD) ratio of at least about 4; and with the
proviso that when L/D is between 0 to 2, the DD is at least 4 so as to
form the filament of essentially uniform molecular orientation across its
cross-section and having a denier of at least about 50 denier per
filament.
2. The process as set forth in claim 1, wherein said thermotropic liquid
crystalline
polymer is selected from the group consisting of wholly aromatic polyesters,
aromatic-aliphatic polyesters, aromatic polyazomethines, aromatic
polyesteramides, aromatic
polyamides, and aromatic polyester-carbonates.
3. The process as set forth in claim 1, wherein said thermotropic liquid
crystalline
polymer is a wholly aromatic polyester.
4. The process as set forth in claim 3, wherein said polyester comprises a
melt
processable wholly aromatic polyester capable of forming an anisotropic melt
phase at
33

a temperature below approximately 350 °C consisting essentially of the
recurring
moieties I and II wherein:
<IMG>
wherein said polyester comprises about 10 to about 90 mole percent of moiety
I, and
about 10 to about 90 mole percent of moiety II.
5. The process as set forth in claim 3, wherein said polyester comprises a
melt
processable wholly aromatic polyester capable of forming an anisotropic melt
phase at
a temperature below approximately 400 °C consisting essentially of the
recurring
moieties I, II, III, and VII wherein:
<IMG>
34

<IMG>
wherein said polyester comprises about 40 to about 70 mole percent of moiety
I, about
1 to about 20 mole percent of moiety II, and about 14.5 to about 30 mole
percent each
of moieties III and VII.
6. The process as set forth in claim 1, wherein said thermotropic liquid
crystalline
polymer is a wholly aromatic polyesteramide.
7. The process as set forth in claim 6, wherein said polyesteramide comprises
a
melt processable wholly aromatic polyesteramide capable of forming an
anisotropic
melt phase at a temperature below approximately 360°C consisting
essentially of the
recurring moieties II, I, and VI wherein:
<IMG>
35

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety
II, about 15 to about 30 mole percent each of moieties I, and VI.
8. The process as set forth in claim 6, wherein said polyesteramide comprises
a
melt processable wholly aromatic polyesteramide capable of forming an
anisotropic
melt phase at a temperature below approximately 380 °C consisting
essentially of the
recurring moieties I, II, III, VII and VI wherein:
<IMG>
36

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 1 to about 20 mole percent of moiety II, about 14.5 to about 30 mole
percent of
moiety III, about 7 to about 27.5 mole percent of moiety VII, and about 2.5 to
about
7.5 mole percent of moiety VI.
9. The process as set forth in claim 6, wherein said polyesteramide comprises
a
melt processable wholly aromatic polyesteramide capable of forming an
anisotropic
melt phase at a temperature below approximately 350 °C consisting
essentially of the
recurring moieties I, II, III, IV, V, and VI wherein:
<IMG>
37

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 10 to about 20 mole percent of moiety II, about 2.5 to about 20 mole
percent of
moiety III, about 0 to about 3 mole percent of moiety IV, about 12.5 to about
27.5
mole percent of moiety V and about 2.5 to about 7.5 mole percent of moiety VI.
38

10. The process as set forth in claim 1, wherein said thermotropic liquid
crystalline
polymer is heated to a temperature of from about 20 °C to about 50
°C above its
melting transition.
11. The process as set forth in claim 1, wherein said aspect ratio (L/D) is
from
about 1 to about 10.
12. The process as set forth in claim 1, wherein said aspect ratio (L/D) is
from
about 1 to about 3.
13. The process as set forth in claim 1, wherein said draw-down ratio is from
about
4 to about 20.
14. The process as set forth in claim 1, wherein said draw-down ratio is from
about
4 to about 15.
15. The process as set forth in claim 1, wherein said filaments are a
monofilament.
16. The process as set forth in claim 15, wherein denier of said filament is
from
about 100 to about 1000 denier per filament.
17. The process as set forth in claim 15, wherein denier of said filament is
from
about 150 to about 500 denier per filament.
18. The process as set forth in claim 15, wherein denier of said filament is
from
about 180 to about 300 denier per filament.
19. The product produced by the process of claim 1.
20. The product produced by the process of claim 4.
21. The product produced by the process of claim 5.
39

22. The product produced by the process of claim 7.
23. The product produced by the process of claim 8.
24. The product produced by the process of claim 9.
25. The product produced by the process of claim 17.
26. The product produced by the process of claim 18.
27. A process for forming a heat-treated filament of a thermotropic liquid
crystalline polymer having the following properties:
(i) denier of at least about 50 denier per filament;
(ii) tenacity of at least about 20 grams per denier;
(iii) modulus of at least about 600 grams per denier; and
(iv) elongation of at least about 3 percent;
said process comprising the steps of:
(a) heating a thermotropic liquid crystalline polymer to a temperature of
about 15°C to about 50°C above its melting transition to form a
fluid
stream of said polymer;
(b) extruding said stream of polymer through a heated cylindrical spinneret
having at least one extrusion capillary to form a filament, wherein said
capillary has an aspect ratio of length to diameter (L/D) in the range of
from about 1 to about 10;
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down ratio of from about 5 to about 40 so as to
form a filament of essentially uniform molecular orientation across the
cross-section and having a denier in the range of from about 50 to
about 1000 denier per filament; and
(d) heat-treating said filament at suitable temperature and pressure
conditions for a sufficient period of time, optionally in the presence of
an inert atmosphere, to form the heat-treated filament.
40

28. The process as set forth in claim 27, wherein said thermotropic liquid
crystalline polymer is selected from the group consisting of:
(i) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I and II wherein:
<IMG>
wherein said polyester comprises about 10 to about 90 mole percent of moiety
I, and
about 10 to about 90 mole percent of moiety II;
(ii) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 400°C
consisting
essentially of the recurring moieties I, II, III, and VII wherein:
<IMG>
41

<IMG>
wherein said polyester comprises about 40 to about 70 mole percent of moiety
I, about
1 to about 20 mole percent of moiety II, and about 14.5 to about 30 mole
percent each
of moieties III and VII;
(iii) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 360°C
consisting
essentially of the recurring moieties II, I, and VI wherein:
<IMG>
42

I is
<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety
II, about 15 to about 30 mole percent each of moieties I, and VI;
(iv) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 380°C
consisting
essentially of the recurring moieties I, II, III, VII and VI wherein:
<IMG>
43

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 1 to about 20 mole percent of moiety II, about 14.5 to about 30 mole
percent of
moiety III, about 7 to about 27.5 mole percent of moiety VII, and about 2.5 to
about
7.5 mole percent of moiety VI; and
(v) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I, II, III, IV, V, and VI wherein:
<IMG>
44

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 10 to about 20 mole percent of moiety II, about 2.5 to about 20 mole
percent of
moiety III, about 0 to about 3 mole percent of moiety IV, about 12.5 to about
27.5
mole percent of moiety V and about 2.5 to about 7.5 mole percent of moiety VI.
29. The process as set forth in claim 27, wherein said aspect ratio (L/D) is
from
about 1 to about 3.
30. The process as set forth in claim 27, wherein said heat treatment in step
(d) is
carried out in stages at a final temperature of about 10°C to about 15
°C below the
melting transition of said thermotropic liquid crystalline polymer.
45

31. The process as set forth in claim 27, wherein denier of said filament is
from
about 150 to about 500 denier per filament.
32. The process as set forth in claim 27, wherein denier of said filament is
from
about 180 to about 300 denier per filament.
33. The product produced by the process of claim 27.
34. The product produced by the process of claim 28.
35. The product produced by the process of claim 29.
36. The product produced by the process of claim 30.
37. The product produced by the process of claim 31.
38. An as-spun filament of a thermotropic liquid crystalline polymer having
the
following properties:
(a) denier of at least about 50 denier per filament;
(b) tenacity of at least about 8 grams per denier;
(c) modulus of at least about 450 grams per denier; and
(d) elongation of at least about 2 percent.
39. The filament as set forth in claim 38, wherein said thermotropic liquid
crystalline polymer is selected from the group consisting of:
(i) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I and II wherein:
46

<IMG>
wherein said polyester comprises about 10 to about 90 mole percent of moiety
I, and
about 10 to about 90 mole percent of moiety II;
(ii) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 400°C
consisting
essentially of the recurring moieties I, II, III, and VII wherein:
<IMG>
47

<IMG>
wherein said polyester comprises about 40 to about 70 mole percent of moiety
I, about
I to about 20 mole percent of moiety II, and about 14.5 to about 30 mole
percent each
of moieties III and VII;
(iii) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 360 °C
consisting
essentially of the recurring moieties II, I, and VI wherein:
<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 15 to about 30 mole percent each of moieties II, and III;
48

(iv) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 380°C
consisting
essentially of the recurring moieties I, II, III, VII and VI wherein:
<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 1 to about 20 mole percent of moiety II, about 14.5 to about 30 mole
percent of
49

moiety III, about 7 to about 27.5 mole percent of moiety VII, and about 2.5 to
about
7.5 mole percent of moiety VI; and
(v) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I, II, III, IV, V, and VI wherein:
<IMG>
50

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 10 to about 20 mole percent of moiety II, about 2.5 to about 20 mole
percent of
moiety III, about 0 to about 3 mole percent of moiety IV, about 12.5 to about
27.5
mole percent of moiety V and about 2.5 to about 7.5 mole percent of moiety VI.
40. The filament as set forth in claim 38, wherein denier of said filament is
from
about 100 to about 1000 denier per filament.
41. The filament as set forth in claim 38, wherein denier of said filament is
from
about 150 to about 500 denier per filament.
42. The filament as set forth in claim 38, wherein denier of said filament is
from
about 180 to about 300 denier per filament.
43. A heat-treated filament of a thermotropic liquid crystalline polymer
having the
following properties:
(a) denier of at least about 50 denier per filament;
(b) tenacity of at least about 20 grams per denier;
(c) modulus of at least about 600 grams per denier; and
(d) elongation of at least about 3 percent.
44. The filament as set forth in claim 43, wherein said thermotropic liquid
crystalline polymer is selected from the group consisting of:
(i) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I and II wherein:
I is
51

<IMG>
wherein said polyester comprises about 10 to about 90 mole percent of moiety
I, and
about 10 to about 90 mole percent of moiety II;
(ii) a melt processable wholly aromatic polyester capable of forming an
anisotropic melt phase at a temperature below approximately 400 °C
consisting
essentially of the recurring moieties I, II, III, and VII wherein:
I is
<IMG>
52

<IMG>
wherein said polyester comprises about 40 to about 70 mole percent of moiety
I, about
1 to about 20 mole percent of moiety II, and about 14.5 to about 30 mole
percent each
of moieties III and VII;
(iii) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 360°C
consisting
essentially of the recurring moieties II, I, and VI wherein:
<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety
II, about 15 to about 30 mole percent each of moieties I, and VI;
(iv) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 380°C
consisting
essentially of the recurring moieties I, II, III, VII and VI wherein:
53

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 1 to about 20 mole percent of moiety II, about 14.5 to about 30 mole
percent of
moiety III, about 7 to about 27.5 mole percent of moiety VII, and about 2.5 to
about
7.5 mole percent of moiety VI; and
54

(v) a melt processable wholly aromatic polyesteramide capable of forming
an anisotropic melt phase at a temperature below approximately 350°C
consisting
essentially of the recurring moieties I, II, III, IV, V, and VI wherein:
<IMG>
55

<IMG>
wherein said polyesteramide comprises about 40 to about 70 mole percent of
moiety I,
about 10 to about 20 mole percent of moiety II, about 2.5 to about 20 mole
percent of
moiety III, about 0 to about 3 mole percent of moiety II, about 12.5 to about
27.5
mole percent of moiety V and about 2.5 to about 7.5 mole percent of moiety VI.
45. The filament as set forth in claim 43, wherein denier of said filament is
from
about 100 to about 1000 denier per filament.
46. The filament as set forth in claim 43, wherein denier of said filament is
from
about 150 to about 500 denier per filament.
47. The filament as set forth in claim 43, wherein denier of said filament is
from
about 180 to about 300 denier per filament.
56

Description

CA 02280627 1999-08-17
Docket 8298
PROCESS FOR MAKING HIGH DENIER FILAMENTS OF
THERMOTROP1C LIQU1D CRYSTALLINE POLYMERS AND
COMPOS1TIONS THEREOF
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to processes for forming filaments of a
thermotropic liquid crystalline polymer. Specifically, the present invention
provides
processes for forming as-spun and heat-treated high denier filaments of a
variety of
thermotropic liquid crystalline wholly aromatic polyesters and
polyesteramides. This
invention also relates to as-spun and heat-treated high denier filaments of
thermotropic
liquid crystalline polyesters and polyesteramides.
Description of the Prior Art
Thermotropic liquid crystalline polymers (LCPs) are an important class of
15 polymers, which are generally wholly aromatic molecules containing a
variety of
heteroatom linkages including ester and/or esteramide linkages. Upon heating
to
sufficiently high temperature, LCPs melt to form a liquid crystalline melt
phase (often
referred to as "anisotropic phase") rather than an isotropic melt. Generally,
LCPs
consist of linear ("rigid rod") molecules that can line up to yield the
desired liquid
2o crystalline order. As a result, LCPs feature low melt viscosity and thus
improved
performance and processabilities.
Because LCPs orient to form "rigid rod" linear molecules, LCPs exhibit
extremely high mechanical properties. Thus, it is well known in the art that
LCPs can
be formed into shaped articles, such as films, rods, pipes, fibers, and
various other
25 molded articles. In addition, it is also known in the art that LCPs,
particularly in the
fiber form, exhibit exceptionally high mechanical properties after a heat
treatment
process. However, all of the known methods in the art describe formation of
only the
low denier fibers, e.g., of about 10 deniers per filament (dpf), which exhibit
high
mechanical properties in their as-spun as well as heat-treated forms.
3o Thus it is an object of the present invention to provide a process for
forming
uniformly oriented high denier LCP filaments. The high denier filament means a
filament of higher than SO dpf.

CA 02280627 1999-08-17
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It is also an object of the present invention to provide a process for forming
high denier LCP filaments of higher than 50 dpf, which exhibit enhanced
mechanical,
thermal and chemical resistance properties in the as-spun as well as heat-
treated form.
It is further an object of the present invention to provide a process for
forming
high denier LCP filaments, which exhibit properties comparable to those of low
denier
LCP filaments (i.e., filaments of less than 10 dpf) in their as-spun as well
as heat
treated states.
It is also an object of the present invention to provide high denier LCP
filaments of higher than 50 dpf having properties comparable to those of low
denier
to LCP filaments of less than 10 dpf.
Finally, it is an object of the present invention to provide a cost-effective,
industrially economic way to heat-treat the high denier filaments of this
invention
directly on the bobbin to produce high denier filaments of superior mechanical
and
physical properties.
There is high desirability in forming uniformly oriented high denier LCP
filaments, which exhibit enhanced mechanical, thermal and chemical resistance
properties in the as-spun as well as heat-treated form. For example, high
denier LCP
filaments can replace steel wires in steel belted tires. Furthermore, since
LCP filaments
are of substantially lower density when compared with steel wires, LCP
filaments are
2o expected to feature much superior properties than that exhibited by the
steel wires. It
is further obvious from the following prior art that there is a real need for
high denier
LCP filaments that exhibit enhanced mechanical, thermal, and chemical
resistance
properties.
Prior Art
The following references are disclosed as background prior art.
U. S. Patent No. 4, I 83,895 describes a process for treating anisotropic melt
forming polymeric products. A process of heat treatment obtained the fibers
having
enhanced mechanical properties and the fiber tenacity was increased by at
least 50%
and to at least 10 grams per denier.
3o U.S. Patent No. 4,468,364 teaches a process for extruding thermotropic
liquid
crystalline polymers (LCPs). It is claimed that extrusion of an LCP through a
die
orifice having an L/D ratio of less than 2 (preferably 0), and at a draw-down
ratio of
2

CA 02280627 1999-08-17
Docket 8298
less than 4 (preferably 1), one can obtain filaments featuring high mechanical
properties.
U.S. Patent No. 4,910,057 describes a highly elongated member of
substantially uniform cross-sectional configuration, which is capable of
improved
service as a stiffening support in an optical fiber cable.
U.S. Patent No. 5,246,776 teaches an aramid monofilament and method of
making the same.
U.S. Patent No. 5,427,165 describes a reinforcement assemblage formed at
least in part of continuous monofilaments of liquid crystal organic
polymer(s). The
to polymers used therein are primarily aramids.
Japanese laid open Patent No. 4-333616 teaches a method of manufacturing
filaments of 50 to 2000 dpf from molten liquid crystalline polymers. The heat-
treated
mechanical properties of these filaments were significantly inferior than the
properties
reported for the corresponding lower denier filaments of S to 10 dpf.
J. Rheology 1992, Vol. 36 (p. 1057-1078) reports a study of the rheology and
orientation behavior of a thermotropic liquid crystalline polyester using
capillary dies
of different aspect ratios.
J. Appl. Polym. Sci. 1995, Vol. 55 (p. 1489-1493) reports orientation
distribution in extruded rods of a thermotropic liquid crystalline polyesters.
The
orientation function increases with increasing apparent shear rate from 166 to
270
sec', but decreases with increasing apparent shear rate from 566 to 780 sec 1.
All of the references described herein are incorporated herein by reference in
their entirety.
SUMMARY OF THE INVENTION
Unexpectedly and surprisingly it has now been found that both as-spun and
heat-treated high denier filaments of at least 50 denier per filaments can be
made that
feature essentially uniform molecular orientation across the cross-section.
Furthermore, these high denier filaments feature remarkably good tensile
properties
retaining at least 80 to 90 percent of the properties expected of conventional
low
3o denier - 5 to 10 dpf - filaments, which was hitherto unattainable by any of
the known
prior art references as briefly described hereinabove.
3

CA 02280627 1999-08-17
Docket 8298
Thus, in accordance with this invention there is provided a process for
forming
an as spun filament of a thermotropic liquid crystalline polymer having the
following
properties:
(i) denier of at least about SO denier per filament;
(ii) tenacity of at least about 8 grams per denier;
(iii) modulus of at least about 450 grams per denier; and
(iv) elongation of at least about 2 percent.
The process of the present invention is comprised of the following steps:
(a) heating a thennotropic liquid crystalline polymer to a temperature of at
least about 15 °C above its melting transition to form a fluid stream
of
said thermotropic polymer;
(b) passing said stream through a heated extrusion chamber, wherein said
chamber is disposed with a suitable cylindrical orifice to form the
filament of said polymer, and wherein said cylindrical orifice has an
aspect ratio of length to diameter (L/D) greater than about 1 and less
than about 15; and
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down (DD) ratio of at least about 4; and with the
proviso that when L/D is between 0 to 2, the DD is at least 4 so as to
2o form the filament of essentially uniform molecular orientation across its
cross-section and having a denier of at least about 50 denier per
filament.
In another aspect of the invention there is also provided a process for
forming a
heat-treated filament of a thermotropic liquid crystalline polymer having the
following
properties:
(i) denier of at least about 50 denier per filament;
(ii) tenacity of at least about 20 grams per denier;
(iii) modulus of at least about 600 grams per denier; and
(iv) elongation of at least about 3 percent.
so Thus in accordance with this aspect of the present invention, the process
is
comprised of the following steps:
4

CA 02280627 1999-08-17
Docket 8298
(a) heating a thermotropic liquid crystalline polymer to a temperature of
about 15 °C to about 50 °C above its melting transition to form
a fluid
stream of said polymer;
(b) extruding said stream of polymer through a heated cylindrical spinneret
having at least one extrusion capillary to form a filament, wherein said
capillary has an aspect ratio of length to diameter (L/D) in the range of
from about 1 to about 10;
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down ratio of from about 5 to about 40 so as to
Io form a filament of essentially uniform molecular orientation across the
cross-section and having a denier in the range of from about 50 to
about 1000 denier per filament; and
(d) heat-treating said filament at suitable temperature and pressure
conditions for a sufficient period of time, optionally in the presence of
an inert atmosphere, to form the heat-treated filament.
In yet another aspect of this invention there is also provided an as-spun
filament
of a thermotropic liquid crystalline polymer.
In a further aspect of this invention there is also provided a heat-treated
filament of a thermotropic liquid crystalline polymer.
2o In another facet of this invention there is also provided a process for
heat
treating the high denier filaments of this invention directly on the bobbin on
which they
were wound while spinning.
Other aspects and advantages of the present invention are described further in
the following detailed description of the preferred embodiments thereof.
Examples of the aromatic-aliphatic polyesters and polyesteramides which may
be used in practicing the invention may include those having the following
structures.
I is
O
w
~O
5

II is
CA 02280627 1999-08-17
a
III is
~l
IV is
O O
V is
/ \ O
W
to
VI is
L. \~ ~ / ~~
ana
VII is
'O ~ ~ O
6

CA 02280627 1999-08-17
Docket 8298
DETA1LED DESCRIPTION OF THE 1NVENTION
In accordance with this invention there is provided a process for forming a
filament of a thermotropic liquid crystalline polymer having the following
properties:
(i) denier of at least about SO denier per filament;
(ii) tenacity of at least about 8 grams per denier;
(iii) modulus of at least about 450 grams per denier; and
(iv) elongation of at least about 2 percent.
The process of the present invention is comprised of the following steps:
(a) heating a thermotropic liquid crystalline polymer to a temperature of at
to least about 15 °C above its melting transition to form a fluid
stream of
said thermotropic polymer;
(b) passing said stream through a heated extrusion chamber, wherein said
chamber is disposed with a suitable cylindrical orifice to form the
filament of said polymer, and wherein said cylindrical orifice has an
aspect ratio of length to diameter (L/D) greater than about 1 and less
than about 15; and
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down (DD) ratio of at least about 4; and with the
proviso that when L/D is between 0 to about 2, the DD is at least 4 so
2o as to form the filament of essentially uniform molecular orientation
across its cross-section and having a denier of at least about 50 denier
per filament.
As discussed hereinabove, prior art references disclose various processes for
the manufacture of filaments of thermotropic polymers, including high denier
filaments.
A specific example of a method to prepare high denier filaments is disclosed
in U. S.
Patent No. 4,468,364, which is incorporated herein by reference in its
entirety. In this
work, the thermotropic polymers were extruded from larger diameter jets at low
draw-
downs which automatically gave thicker filaments. The polymer melt was also
extruded at low throughputs, i.e., speed of polymer in the jet, and taking the
filaments
3o up at low speed. This means that most of the orientation of the filament is
obtained
from the converging flow in the jet itself which explains why increasing the
capillary
length causes a reduction in orientation, i.e. orientation or filament
modulus. Passage
7

CA 02280627 1999-08-17
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of the polymer through the capillary prior to exiting the jet will lead to
disorientation of
the flow which had been induced by the converging part of the jet above the
capillary.
Unlike the process conditions of the prior art discussed hereinabove, the
process of the present invention operates at higher draw-downs with the result
that the
filament undergoes elongation to decrease the filament diameter once it
emerges from
the jet orifice. This elongational flow puts most of the orientation into the
filament,
thus providing a filament having essentially uniform cross-sectional
orientation.
Furthermore, the present invention also provides a commercially practical
process in which the polymer throughput can be increased. Because the pressure
over
1o the jet will increase linearly with throughput, the pressure will reach
impractical levels
for small jets.
In accordance with the process of the present invention, the preferred
polymers
are thermotropic liquid crystalline polymers. Thermotropic liquid crystal
polymers are
polymers which are liquid crystalline (i.e., anisotropic) in the melt phase.
Thermotropic liquid crystal polymers include wholly aromatic polyesters,
aromatic-
aliphatic polyesters, aromatic polyazomethines, aromatic polyesteramides,
aromatic
polyamides, and aromatic polyester-carbonates. The aromatic polyesters are
considered to be "wholly" aromatic in the sense that each moiety present in
the
polyester contributes at least one aromatic ring to the polymer backbone.
2o Specific examples of suitable aromatic-aliphatic polyesters are copolymers
of
polyethylene terephthalate and hydroxybenzoic acid as disclosed in Polyester
X7G-A
Self Reinforced Thermoplastic, by W. J. Jackson, Jr., H. F. Kuhfuss, and T. F.
Gray,
Jr., 30th Anniversary Technical Conference, 1975 Reinforced
Plastics/Composites
Institute, The Society of the Plastics Industry, Inc., Section 17-D, Pages 1-
4. A
further disclosure of such copolymer can be found in "Liquid Crystal Polymers:
I.
Preparation and Properties of p-Hydroxybenzoic Acid Copolymers," Journal of
Polymer Science, Polymer Chemistry Edition, Vol. 14, pp. 2043-58 (1976), by W.
J.
Jackson, Jr. and H. F. Kuhfuss. The above-cited references are herein
incorporated by
reference in their entirety.
3o Aromatic polyazomethines and processes of preparing the same are disclosed
in
the U.S. Patent Nos. 3,493,522; 3,493,524; 3,503,739; 3,516,970; 3,516,971;
3,526,611; 4,048,148; and 4,122,070. Each of these patents is herein
incorporated by
reference in its entirety. Specific examples of such polymers include
poly(nitrilo-2-
8

CA 02280627 1999-08-17
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methyl-1,4-phenylenenitriloethylidyne-1,4-phenyleneethylidyne); poly(nitrilo-2-
methyl-
1,4-phenylene-nitrilomethylidyne-1,4-phenylenemethylidyne); and poly(nitrilo-2-
chloro-1,4-phenylenenitrilomethylidyne-1,4-phenylene-methylidyne).
Aromatic polyesteramides are disclosed in U.S. Patent Nos. 5,204,443,
4,330,457, 4,966,956, 4,355,132, 4,339,375, 4,351,917 and 4,351,918. Each of
these
patents is herein incorporated by reference in its entirety. Specific examples
of such
polymers include polymer formed from the monomers comprising 4-hydroxybenzoic
acid, 2,6-hydroxynaphthoic acid, terephthalic acid, 4,4'-biphenol, and 4-
aminophenol;
and polymer formed from the monomers comprising 4-hydroxybenzoic acid, 2,6-
naphthalene dicarboxylic acid, terephthalic acid, isophthalic acid,
hydroquinone, and 4-
aminophenol.
Preferred aromatic polyamides are those which are melt processable and form
thermotropic melt phase as described hereinabove. Specific examples of such
polymers include polymer formed from the monomers comprising terephthalic
acid,
isophthalic acid, and 2,2'-bis(4-aminophenyl)propane.
Aromatic polyester-carbonates are disclosed in U. S. Patent No. 4,107,143,
which is herein incorporated by reference in its entirety. Examples of such
polymers
include those consisting essentially of hydroxybenzoic acid units,
hydroquinone units,
carbonate units, and aromatic carboxylic acid units.
2o The liquid crystal polymers which are preferred for use in the process of
the
present invention are the thermotropic wholly aromatic polyesters. Specific
examples
of such polymers may be found in U.S. Patent Nos. 3,991,013; 3,991,014;
4,057,597;
4,066,620; 4,075,262; 4,118,372; 4,146,702; 4,153,779; 4,156,070; 4,159,365;
4,169,933; 4,181,792; and 4,188,476, and U.K. Application No. 2,002,404. Each
of
these patents is herein incorporated by reference in its entirety.
Wholly aromatic polyesters which are preferred for use in the present
invention
are disclosed in commonly-assigned U.S. Patent Nos. 4,067,852; 4,083,829;
4,130,545; 4,161,470; 4,184,996; 4,238,599; 4,238,598; 4,230,817; 4,224,433;
4,219,461; and 4,256,624. The disclosures of all of the above-identified
commonly-
3o assigned U.S. patents and applications are herein incorporated by reference
in their
entirety. The wholly aromatic polyesters disclosed therein typically are
capable of
forming an anisotropic melt phase at a temperature below approximately 350
°C.

CA 02280627 1999-08-17
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The wholly aromatic polyesters which are suitable for use in the process of
the
present invention may be formed by a variety of ester-forming techniques
whereby
organic monomer compounds possessing functional groups which upon condensation
form the requisite recurring moieties are reacted. For instance, the
functional groups
of the organic monomer compounds may be carboxylic acid groups, hydroxyl
groups,
ester groups, acyloxy groups, acid halides, etc. The organic monomer compounds
may
be reacted in the absence of a heat exchange fluid via a melt acidolysis
procedure.
They, accordingly, may be heated initially to form a melt solution of the
reactants with
the reaction continuing as solid polymer particles are suspended therein. A
vacuum
to may be applied to facilitate removal of volatiles formed during the final
stage of the
condensation (e.g., acetic acid or water).
In commonly-assigned U.S. Patent No. 4,083,829, entitled "Melt Processable
Thermotropic Wholly Aromatic Polyester," is described a slurry polymerization
process which may be employed to form the wholly aromatic polyesters which are
Is preferred for use in the present invention. According to such a process,
the solid
product is suspended in a heat exchange medium. The disclosure of this patent
has
previously been incorporated herein by reference in its entirety.
When employing either the melt acidolysis procedure or the slurry procedure of
U.S. Patent No. 4,083,829, the organic monomer reactants from which the wholly
2o aromatic polyesters are derived may be initially provided in a modified
form whereby
the usual hydroxy groups of such monomers are esterified (i.e., they are
provided as
lower acyl esters). The lower acyl groups preferably have from about two to
about
four carbon atoms. Preferably, the acetate esters of organic monomer reactants
are
provided.
25 Representative catalysts which optionally may be employed in either the
melt
acidolysis procedure or in the slurry procedure of U.S. Patent No. 4,083,829
include
dialkyl tin oxide (for example, dibutyl tin oxide), diaryl tin oxide, titanium
dioxide,
antimony trioxide, alkoxy titanium silicates, titanium alkoxides, alkali and
alkaline earth
metal salts of carboxylic acids (for example, zinc acetate), gaseous acid
catalysts such
3o as Lewis acids (for example, BF3), hydrogen halides (for example, HCl), and
similar
catalyst known to one skilled in the art. The quantity of catalyst utilized
typically is
about 0.001 to about 1 percent by weight based upon the total monomer weight,
and
most commonly about 0.01 to about 0.2 percent by weight.

CA 02280627 1999-08-17
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The wholly aromatic polyesters which are preferred for use in the present
invention commonly exhibit a weight average molecular weight of about 10,000
to
about 200,000, and preferably about 20,000 to about 50,000, (for example,
about
30,000 to about 40,000). Such molecular weight may be determined by commonly
used techniques, such as, gel permeation chromatography or solution viscosity
measurements. Other methods include end group determination via infrared
spectroscopy on compression molded films or nuclear magnetic resonance
spectroscopic (NNm) measurements of polymeric solutions or solid phase NMR of
polymer powder or films. Alternatively, light scattering techniques in a
1o pentafluorophenol solution may be employed to determine the molecular
weight.
The wholly aromatic polyesters or polyesteramides additionally commonly
exhibit an inherent viscosity (i.e., I.V.) of at least about 2.0 dL/g, for
example, about
2.0 to about 10.0 dL/g, when dissolved in a concentration of 0.1 percent by
weight in a
1:1 solvent mixture of hexafluoroisopropanol(HFIP)/pentafluorophenol (PFP)
(v/v) at
25 °C.
Especially preferred polymers for the process of this invention are wholly
aromatic polyesters and polyesteramides. In preferred embodiments of this
invention,
specifically preferred polyesters are listed below:
a) The wholly aromatic polyester capable of forming an anisotropic melt phase
2o at a temperature below approximately 350 °C consisting essentially
of the recurring
moieties I and II wherein:
I is
O
\ w
O
1~

CA 02280627 1999-08-17
Docket 8298
and
II is
O
\ \
/ /
O
The wholly aromatic polyester as described above is disclosed in U. S. Patent
No. 4,161,470. The polyester comprises about 10 to about 90 mole percent of
moiety
I, and about 10 to about 90 mole percent of moiety II. In one embodiment,
moiety II
is present in a concentration of about 65 to about 85 mole percent, and
preferably in a
concentration of about 70 to about 80 mole percent; for example, about 75 mole
1o percent. In another embodiment, moiety II is present in a lesser proportion
of about
to about 35 mole percent, and preferably in a concentration of about 20 to
about 30
mole percent.
b) The wholly aromatic polyester capable of forming an anisotropic melt phase
at a temperature below approximately 400 °C consisting essentially of
the recurring
15 moieties I, II, III, and VII wherein:
I is
O
\ w
II is
O
\ \
/ /
0
12

CA 02280627 1999-08-17
Docket 8298
III is
y
and
VII is
~O ~ ~ O~
s
The polyester comprises about 40 to about 60 mole percent of moiety I, about
2 to about 30 mole percent of moiety II, and about 19 to about 29 mole percent
each
of moieties III and VII. In one of the preferred embodiments, the polyester
comprises
about 60 to about 70 mole percent of moiety I, about 3 to about 5 mole percent
of
to moiety II, and about 12.5 to about 18.5 mole percent each of moieties III
and VII.
The preferred polyesteramides of the process of the present invention are
summarized below:
a) The wholly aromatic polyesteramide capable of forming an anisotropic melt
phase at a temperature below approximately 360 °C consisting
essentially of the
15 recurring moieties II, I, and VI wherein:
II is
O
w w
~O
I is
13

CA 02280627 1999-08-17
Docket 8298
and
VI is
/
The wholly aromatic polyesteramide as described above is disclosed in U. S.
Patent No. 4,330,457, which is hereby incorporated herein by reference in its
entirety.
The polyesteramide comprises about 25 to about 75 mole percent of moiety II,
about
37.5 to about 12.5 mole percent each of moieties I and VI. The polyesteramide
preferably comprises about 40 to about 70 mole percent of moiety II, and about
15 to
about 30 mole percent each of moieties I and VI. In one of the preferred
to embodiments of this invention, the polyesteramide comprises about 60 to
about 65
mole percent of moiety II, and about 17.5 to about 20 mole percent each of
moieties I,
and VI.
b) The wholly aromatic polyesteramide capable of forming an anisotropic melt
phase at a temperature below approximately 380 °C consisting
essentially of the
recurring moieties I, II, III, VII and VI wherein:
I is
O
\ w
~O /
II is
0
\ \
w w0 / / w
14

CA 02280627 1999-08-17
Docket 8298
III is
U J
VII is
/ ~ -
and
VI is
The wholly aromatic polyesteramide as described above is disclosed in U. S.
Patent No. 5,204,443, which is hereby incorporated herein by reference in its
entirety.
1o The polyesteramide comprises approximately 40 to 70 mole percent of moiety
I, about
1 to about 20 mole percent of moiety II, about 14.5 to about 30 mole percent
of
moiety III, about 7 to about 27.5 mole percent of moiety VII, and about 2.5 to
about
7.5 mole percent of moiety VI.
c) The wholly aromatic polyesteramide capable of forming an anisotropic melt
phase at a temperature below approximately 350 °C consisting
essentially of the
recurring moieties I, II, III, IV, V, and VI wherein:
I is
O
\ w

CA 02280627 1999-08-17
Docket 8298
II is
~L
III is
J
IV is
V is
~o ~ ~ O
and
to VI is
The polyesteramide as described above, comprises about 40 to about 70 mole
percent of moiety I, about 10 to about 20 mole percent of moiety II, about 2.5
to
about 20 mole percent of moiety III, about 0 to about 3 mole percent of moiety
IV,
t5 about 12.5 to about 27.5 mole percent of moiety V and about 2.5 to about
7.5 mole
percent of moiety VI.
1G

CA 02280627 1999-08-17
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According to the process of the present invention, a fluid stream of liquid
crystal polymer is provided to any conventional extrusion apparatus. This is
achieved
by heating the thermotropic liquid crystalline polymer of the present
invention to form
a melt. Any of the known methods to heat the polymer to form a melt can be
employed in this invention. The particular apparatus used is not critical to
the
operation of the process of the present invention, and any suitable apparatus
may be
used herein. One such apparatus which has been found to be suitable for use
with
thermotropic liquid crystal polymers employs a contact melting method so that
melt
residence time can be kept short and constant. The apparatus includes a heated
surface
to against which a molded rod of liquid crystal polymer is pressed. The fluid
stream of
molten polymer is then introduced to the extrusion chamber inside of which are
disposed a filter pack and a cylindrical orifice. After being passed through
the filter
pack, the polymer melt is extruded through the cylindrical orifice.
In a preferred embodiment, the extrusion chamber is comprised of a single
orifice cylindrical chamber in which the polymer is heated to a temperature in
the range
of about 20 °C to about 50 °C above its melting transition. In
this preferred
embodiment the cylindrical orifice having an aspect ratio (L/D) of about 1 to
about 10
is employed. As used herein, the aspect ratio is meant to define the ratio of
length (L)
to diameter (D) of the cylindrical orifice. In a more preferred embodiment of
this
2o invention, the aspect ratio of the cylindrical orifice is in the range of
about 1 to about
3.
After the fluid stream of the liquid crystal polymer is extruded through the
orifice, the polymer forms an elongated shaped article having the polymer
molecules
oriented substantially parallel to the flow direction. The orientation of the
polymer
molecules can be confirmed by determining orientation angle by X-ray analysis.
The
extruded shaped articles in the form of filaments are then drawn-down and
taken-up on
a filament spool. In accordance with the process of this invention, it is
critical that the
appropriate draw-down ratio be used to exploit maximum benefit from the
practice of
this invention. Thus, in a preferred embodiment, the draw-down ratio in the
range of
3o from about 4 to about 20 is employed. In a more preferred embodiment, the
draw-
down ratio in the range of from about 4 to about 15 is employed. The draw-down
ratio (DD) as used herein is defined as the ratio of cross-sectional area of
the orifice
(A,) to the cross-sectional area of the filament (AZ). This ratio is often
also expressed
17

CA 02280627 1999-08-17
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as the ratio of the take-up speed of the filament (VZ) to the extrusion speed
of the
filament (V,). Thus the draw-down ratio, DD, may be expressed in terms of the
following equation:
DD - Al/Az - V2/V,
Thus, in accordance with the process of the present invention, thermotropic
liquid crystalline polymeric filaments havilng essentially uniform molecular
orientation
that exhibit unusually superior mechanical properties can be made. For
example, by
properly practicing the process of the present invention, it is now possible
to obtain a
high denier filament having hitherto unattainable properties. More
specifically, it has
1o now been found that filaments having a denier in the range of from about
100 to about
1000 denier per filament (dpi can readily be made by following the process of
this
invention. In a preferred embodiment, filaments having a denier in the range
of from
about 150 to about 500 dpf can readily be made. In a more preferred
embodiment,
filaments having a denier in the range of from about 180 to about 300 dpf can
readily
be made. The denier as used herein is defined as a weight in grams of 9,000
meters of
the filament. The dpf as used herein is the denier of an individual continuous
filament.
The conditions of temperature and pressure under which the liquid crystal
polymer can be extruded are not critical to the process of the present
invention and can
easily be determined by one of ordinary skill in the art. Typically,
thermotropic
2o polymers are extruded at a temperature of about 280 °C. to about 400
°C. and at a
pressure of about 100 p.s.i. to about 5,000 p.s.i.
As discussed hereinabove, liquid crystal polymers have very stir, rod-like
molecules. In the quiescent state, the polymer molecules line up in local
regions,
thereby forming ordered arrays or domains. The existence of domain texture
within
the microstructure of a liquid crystal polymer may be confirmed by
conventional
polarized light techniques whereby a polarizing microscope utilizing crossed-
polarizers
is employed.
The mechanical properties of filaments produced in accordance with the
process of the present invention can be improved still further by subjecting
the articles
3o to a heat treatment following extrusion. The articles may be thermally
treated in an
inert atmosphere (e.g., nitrogen, argon, helium). For instance, the article
may be
brought to a temperature about 10 °C to about 30 °C below the
melting temperature of
the liquid crystal polymer, at which temperature the filament remains as a
solid object.
is

CA 02280627 1999-08-17
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The heat treatment times commonly range from a few minutes to a number of
days,
e.g., from about 0.5 to 200 hours, or more. Preferably, the heat treatment is
conducted for a time of about 1 to about 48 hours (e.g., about 24 to about 30
hours).
The heat treatment improves the properties of the article by increasing the
molecular
weight of the liquid crystalline polymer and increasing the degree of
crystallinity.
Thus, in accordance with one of the preferred embodiments of the present
invention there is also provided a process for forming a heat-treated filament
of a
thermotropic liquid crystalline polymer having the following properties:
(i) denier of at least about 50 denier per filament;
to (ii) tenacity of at least about 20 grams per denier;
(iii) modulus of at least about 600 grams per denier; and
(iv) elongation of at least about 3 percent.
The process for forming such a filament is comprised of the following steps:
(a) heating a thermotropic liquid crystalline polymer to a temperature of
about I 5 °C to about 50 °C above its melting transition to form
a fluid
stream of said polymer;
(b) extruding said stream of polymer through a heated cylindrical spinneret
having at least one extrusion capillary to form a filament, wherein said
capillary has an aspect ratio of length to diameter (L/D) in the range of
2o from about 1 to about 10;
(c) winding said filament at a take-up speed of at least about 200 meters
per minute and draw-down ratio of from about 5 to about 40 so as to
form a filament of essentially uniform molecular orientation across the
cross-section and having a denier in the range of from about SO to
2s about 1000 denier per filament; and
(d) heat-treating said filament at suitable temperature and pressure
conditions for a suf~'~cient period of time, optionally in the presence of
an inert atmosphere, to form the heat-treated filament.
Any of the preferred thermotropic polyesters or polyesteramides described
3o hereinabove may be used in this preferred embodiment. Further, as described
herein,
the heat treatment can be carried out in stages at a final temperature of
about 15 °C
below the melting transition of the thermotropic polymer.
19

CA 02280627 1999-08-17
Docket 8298
In another preferred embodiment of this invention there is also provided an as-
spun filament of a thermotropic liquid crystalline polymer having the
following
properties:
(a) denier of at least about 50 denier per filament;
(b) tenacity of at least about 8 grams per denier;
(c) modulus of at least about 450 grams per denier; and
(d) elongation of at least about 2 percent.
In a particularly preferred embodiment of this invention the denier of as-spun
filament is in the range of from about 100 to about 1000 dpf. In a more
particularly
1o preferred embodiment of this invention the denier of as-spun filament is in
the range of
from about 150 to about 500 dpf. In a most particularly preferred embodiment
of this
invention the denier of as-spun filament is in the range of from about 180 to
about 300
dpf.
In yet another preferred embodiment of this invention there is also provided a
heat-treated filament of a thermotropic liquid crystalline polymer having the
following
properties:
(a) denier of at least about 50 denier per filament;
(b) tenacity of at least about 20 grams per denier;
(c) modulus of at least about 600 grams per denier; and
(d) elongation of at least about 3 percent.
In a further aspect of this invention there is also provided a process for
heat
treating the high denier filaments produced in accordance of the process of
this
invention described hereinabove. In this aspect of the invention, the
filaments wound
on the bobbin are directly heat treated to obtain the heat-treated filaments,
thus
of~'ering significant cost savings.
Thus, in accordance with this aspect of the invention, the process is
comprised
of the following steps:
(a) heating a thermotropic liquid crystalline polymer to a temperature of at
least about 15 °C above its melting transition to form a fluid stream
of
3o said thermotropic polymer;
(b) passing said stream through a heated extrusion chamber, wherein said
chamber is disposed with a suitable cylindrical orifice to form the
filament of said polymer, and wherein said cylindrical orifice has an

CA 02280627 1999-08-17
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aspect ratio of length to diameter (L/D) greater than about I and less
than about 15; and
(c) winding said filament on to a bobbin at a low tension of at least about 5
grams and take-up speed of at least about 200 meters per minute and
draw-down (DD) ratio of at least about 4 so as to form the filament of
essentially uniform molecular orientation across its cross-section and
having a denier of at least about SO denier per filament; and
(d) heat treating said filament directly on said bobbin at suitable
temperature and pressure conditions for a suffcient period of time,
to optionally in the presence of an inert atmosphere, to form the heat
treated filament.
Thus, by practicing this aspect of the present invention, it is now possible
to
obtain a heat-treated filament having the following properties:
(i) denier of at least about 50 denier per filament;
(ii) tenacity of at least about 20 grams per denier;
(iii) modulus of at least about 600 grams per denier; and
(iv) elongation of at least about 3 percent.
Any of the thermotropic polymers described hereinabove may be used in this
aspect of the invention. Preferred thermotropic polymers are the polyesters
and
2o polyesteramides as described hereinabove.
Surprisingly, it has now been found that applying low tension while winding
the
filament on to the bobbin markedly improves the tensile properties of the
filaments
after heat treatment. For example, tensions of about 5 grams to 30 grams
appears to
be essential. It is preferred that tensions of about 10 grams is applied to
obtain
maximum benefit from the practice of this invention.
This invention is further illustrated by the following examples, which are
provided for illustration purposes and in no way limit the scope of the
present
invention.
21

CA 02280627 1999-08-17
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Examples (General
In the Examples that follow, the following abbreviations are used:
HBA = 4-Hydroxybenzoic acid
HNA = 2,6-Hydroxynaphthoic acid
TA = Terephthalic acid
IA = Isophthalic acid
NDA = 2,6-Naphthalene dicarboxylic acid
BP = 4,4'-Biphenol
HQ = Hydroquinone
to AA = I-Acetoxy-4-acetamidobenzene
IV = Inherent viscosity
dL/g = deciliters per gram; an unit of measure of IV
wt.% = weight per cent; generally used to represent the concentration of a
solution to measure IV - means grams of polymer in 100 mL of a solvent
mixture.
MV = Melt viscosity
DSC = Differential Scanning Calorimetry
T = Tenacity
M = Modulus
E = Elongation
2o gpd = grams per denier
General Analytical Techniques used for the Characterization of the Polymer: A
variety
of analytical techniques were used to characterize the polymer used and the
filaments
formed according to the present invention, which included the following:
IV: The solution viscosity of the polymer samples, IV, was measured at 25
°C in a
concentration of 0.1 wt.% solution in equal parts by volume of
pentafluorophenol and hexafluoroisopropanol.
MV: MV of polymer samples was measured using a Kayeness Melt Rheometer
Model 2052 equipped with a Hastalloy barrel and plunger tip. The radius of
the die orifice was 0.015 inch and the length was I inch. For the purpose of
determining melt viscosity, a plot of viscosity vs. shear rate was generated
by
measuring the viscosities at shear rates of 56, 166, 944, 2388, and 8333 sec-
',
and viscosities at 100 and 1000 sec'' were interpolated.
22

CA 02280627 1999-08-17
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DSC: DSC of polymer samples was performed on a Perkin Elmer 7700 Thermal
Analysis System. In all runs the samples, sealed in aluminum pans, were heated
or cooled at a rate of 20 °C/min. under a nitrogen atmosphere. The DSC
curves obtained from the second heating run were taken for the analysis.
Light Microscopy: Samples were prepared for microscopic analysis by thin
sectioning using a glass knife microtome. The sections were examined by
polarized light microscopy to observe morphological behavior at ambient
temperatures.
Example 1
This Example 1 demonstrates the general increase in mechanical properties of
an as-spun high denier filament of a liquid crystalline wholly aromatic
polyester
produced in accordance with the present invention, i.e., filaments formed from
a die
having an aspect ratio (L/D) higher than 2 and at a draw-down ratio (DD) equal
to or
higher than 4.
Filaments were formed from a thermotropic liquid crystalline wholly aromatic
HBA/HNA polyester sold under the tradename of "VECTRATM A" (Ticona LLC,
Summit, NJ). This polymer exhibited a melting temperature of 280 °C and
an inherent
viscosity of 6.30 dL/g when measured in a concentration of 0.1 percent by
weight
2o solution in equal parts by volume of pentafluorophenol and
hexafluoroisopropanol at
°C.
A sample of the polymer was dried overnight at 130 °C under
vacuum. The
polymer was melted in a 1 inch diameter extruder, and the extrudate was
metered
using a conventional polymer meter pump to the spinning pack where it was
filtered
25 through 50/80 shattered metal. The melt was then extruded through a single
hole
spinneret of various aspect ratios (L/D) as listed in Table 1. Crossflow
quench was
applied to the emerging filament to provide cooling and a stable spinning
environment.
The quench was situated 4 cm below the spinneret face, and was 120 cm long by
15
cm wide. The quench flow rate at the top was 30 mpm (0.5 mpsec). The
3o monofilament was dressed either with water or with a spinning finish before
passing
around a system of godets which controlled the take-up speed. It was finally
taken up
on a Sahm spool winder.
23

CA 02280627 1999-08-17
Docket 8298
Mechanical properties of the monofilaments produced in accordance with this
Example 1 were measured in accordance with ASTM D3822, and the results are
listed
in Table I. For purposes of comparison, monofilaments were also extruded in
the
manner described above with the exception that the DD ratios were maintained
below
4. In a few of these comparative runs, spinnerets with low aspect ratios (L/D
less than
2) were also used, as listed in Table I. Mechanical properties of these
monofilaments
were measured using the same procedures as described above and are also listed
in
Table I.
The data given in Table I indicate a dramatic improvement in properties of
1o monofilaments extruded with spinnerets having aspect ratio (L!D) higher
than 1 and
DD ratio higher than 4 as compared to those of monofilaments extruded with
spinnerets having aspect ratio (L/D) lower than 2 and at DD ratios lower than
4. This
Example thus demonstrates the beneficial effects achieved by extruding liquid
crystal
polymer through a spinnerets having L/D higher than 2 at a draw-down ratio of
higher
than 4 in accordance with the process of the present invention.
Note: In all Tables herein, all samples were tested at 10-inch gauge length,
20% strain rate, 10
filament break.
Table I
Denier Tenacity Modulus Elongation
Sam le No. L/D Draw-Down d d
38592-46-1 0 56.5 239 5.7 466 1.4
38592-49-1 0 3.0 216 7.4 589 1.6
38445-37-7 I 6.2 219 9 615 1.8
38592-48-1 1 54.7 247 6.4 475 1.5
38664-I-1 1 6.4 225 10.2 597 2
38592-43-1 2 17.3 231 8.5 587 1.8
38592-45-I 10 57.0 237 6 533 1.4
-....
38592-47-2 10 2.3 276 I 466 I 2.4
~ 8.g
Example 2
Monofilaments produced in accordance with Example 1 were subjected to a
heat treatment in stages as follows. Heat treatment of short lengths of the
monofilament was carried out on racks under zero tension in a flow of dry
nitrogen
using a programmed temperature profile. The programmed temperature profiles of
each of the heat treatment of monofilaments are listed in Table II. The heat-
treated
24

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monofilament was tested at 10 inch gauge length; 20% strain rate and 10
filament
break. Following heat treatment, the mechanical properties of the
monofilaments were
measured and are listed in Table II.
The measurements were made using the same tests as in Example 1. The data
demonstrate the increase in properties, which is obtained by subjecting the
monofilaments to staged heat treatment conditions.
Table II
Sample Preheat Heat TreatmentOrifice Den. Ten. Mod. Elong.
Number ConditionCondition Size (g) (gpd)(gpd)(%)
(Draw-down)
38543-02-123UC/2 2 hr hold 0.015" 207 25.64699 3.25
hr a, 270C 6.2
38543-02-3230C/2 8 hr hold 0.015" 211 25.64690 3.31
hr (a~ 270C 6.2
38543-02-5230C/2 14 hr hold 0.015" 213 24.36633 3.17
hr (a7 270C 6.2
38543-03-1None 2 hr hold 0.015" 211 21.69621 3.03
~ 270C (6.2)
38445-38-6None As-S un (Control)0.025" 205 10.1 593 1.88
(17.1)
38543-02-2230C/2 2 hr hold 0.025" 201 22.45682 3.04
hr n 270C 17.1
38543-02-4230C/2 8 hr hold 0.025" 203 24.76641 3.25
hr (aO 270C 17.1)
38543-02-3230C/2 14 hr hold 0.0 213 23.44613 3.31
hr (a7 270C 25'
' (17.1)
38543-03-2None 2 hr hold _ 200 18.12586 2.78
a, 270C _ ~ ~ ~
025 (17.1)
J
to Example 3
Examples 1 and 2 were repeated in this Example 3 except that the high denier
filaments of Vectra A polymer were formed. The Table III summarizes the as-
spun
and heat-treated properties of the filaments.
Table III
Sample Hcat TreatmentOrifice Den. Ten. Mod. Elong.
Size
Number Condition (Draw-down)( ( d d)
38538-1G-6As-Spun 0.015" 228 10.4 546 2.0
38543-09-1230C/2 hr; (G.2) 228 22.3 G08 3.2
270C/2 hr
38538-1G-7As-Spun 0.015" 339 9.8 531 2.0
38543-09-2230C/2 hr; (G.2) 334 18.8 625 2.5
270C/2 hr
38538-1G-8As-Spun 0.015" 449 10.0 532 2.1
38543-09-3230C/2 hr; (G.2) 439 17.1 583 2.7
270C/2 hr
38538-20-3As-Spun 0.025" 461 9.5 543 2.0
38543-09-4230C/2 hr; (17.1) 454 18.5 G48 2.8
270C/2 hr
38538-20-5As-Spun 0.025" G67 9.0 540 1.9
38543-09-5230Cl2 hr; (17.1) 645 17.G 562 2.8
270C/2 hr
38538-20-7As-Spun 0.025" 8G8 8.8 48G 2.1
38543-09-G230C/2 hr; (17.1) 8G6 14.2 528 2.6
270C/2 hr
Example 4

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Examples 1 and 2 were repeated in this Example 4 except that the thermotropic
polyesteramide was employed in this Example 4. A HNA/AA/TA polyesteramide was
used in Example 4 was sold under the tradename of "VECTRATM B" (Ticona LLC,
Summit, NJ). The Table IV-A summarizes the as-spun and heat-treated properties
of
the high denier single filaments formed from this polymer.
Table IV-A
Sample Heat TreatmentOrificeDen. Ten. Mod. Elong.
Number Condition Size ( d %)
d
38445-44-2As-S nn 0.015" 213 9.5 698 1.80
38543-OG-12 hr Prchcat 0.015" 211 11.1 G76 1.92
a, 230C;
2 hr hold (n),
270C
38543-OG-32 hr Prchcat 0.015" 208 16.8 697 2.60
a 230C;
8 hr hold a,
270C
38543-OG-52 hr Preheat 0.015" 208 21.6 710 3.00
a 230C;
14 hr hold
n, 270C
38445-44-4As-S nn 0.025" 235 9.4 705 1.?8
38543-OG-22 hr Preheat 0.025" 228 11.0 680 1.89
n 230C;
2 hr hold a,
270C
38543-OG-42 hr Preheat 0.025" 228 17.1 702 2.59
a 230C;
8 hr hold n,
270C
38543-OG-G2 hr Preheat 0.025" 232 20.8 698 2.97
O 230C;
14 hr hold
rr, 270C
to A few of the filament samples extruded from VECTRATM B were also heat
treated under optimal temperature and time conditions. The results of which
are listed
in Table IV-B
Table IV-B
Sample Heat TreatmentOrifice Den. Ten. Mod. Elong.
Number Condition Size ( ( ( %)
~) d) d)
38445-44-2As-S un 0.015" 213 9.5 698 1.80
38543-10-12G0C/lhr; 290C/2hr;0.015" 207 15.4 676 2.4
300C/2hr
38543-10-22G0C/lhr; 280C/2hr;0.015" 204 24.9 705 3.6
300C/2hr
38543-10-3230C/2hr; 270C/2hr;0.015" 206 20.1 709 3.0
290C/2hr
38543-10-4230C/2hr; 250C/2hr;0.015" 210 7.7 717 1.3
280C/2hr
38543-10-5230C/2hr; 0.015" 212 17.7 739 2.6
270C/l8hr
38445-44-4As-S un 0.025" 235 9.4 705 1.78
38543-10-G230C/2hr; 0.015" 230 18.6 755 2.6
270C/l8hr
Example 5
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Examples 1 and 2 were repeated in this Example 5 except that the thermotropic
polyesteramide was employed in this Example 5. The polyesteramide used in this
Example comprises HBA, HNA, TA, BP and AA units, and is sold under the
tradename of "VECTRAT"' Ei" (Ticona LLC, Summit, NJ). Table V summarizes the
as-spun and heat-treated properties of the high denier single filaments formed
from this
polymer.
Table V
Sample Hcat TreatmentOrificeDenier TenacityModulusElongation
Size
Number Condition (Draw- (g) (gpd) (gpd) (%)
down)
38445-49-8As-Spun 0.015" 219 7.0 576 1.30
(6.2)
38543-07-1No Preheat 0.015" 214 21.7 819 2.6
2 hr o, (6.2)
300C
38543-07-3No Preheat 0.015" 214 23.5 837 2.5
6 hr a, (6.2)
300C
38543-07-5No Preheat 0.015" 210 23.6 857 2.5
10 hr n, (6.2)
300C
38538-O1-1As-Spun 0.025" 227 6.6 608 1.15
(17.1)
38543-07-2No Preheat 0.025" 216 19.8 838 2.2
2 hr (n7, (17.1)
300C
38543-07-4No Prchcat 0.025" 222 21.2 856 2.2
6 hr n, (17.1)
300C
38543-07-6No Prchcat 0.015" 230 21.4 841 2.3
10 hr a, (17.1)
300C
Example 6
Examples 1 and 2 were repeated in this Example 6 except that the thermotropic
polyesteramide was employed in this Example G. The polyesteramide used in this
Example comprises HBA, 1-INA, TA, BP and AA units, and is sold under the
tradename of "VECTRATM L" (Ticona LLC, Summit, NJ). Table VI summarizes the
as-spun and heat-treated properties of the high denier single filaments formed
from this
polymer.
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Table VI
Sample Heat TreatmentOrifice Den. Ten. Mod. Elong.
No. Size
Condition Draw-down d d
38538-25-1As-Spun 0.015" 228 8.6 551 1.6
6.2
38543-11-1230C/2hrs. 0.015" 223 20.4 671 3.0
270C/8hrs. 6.2
38543-11-3230C/2hrs. 0.015" 225 21.7 697 2.6
270C/l6hrs. 6.2
38543-11-5300C/8hrs. 0.015" 221 19.0 607 2.7
6.2
38538-26-1As-Spun 0.025" 233 7.5 564 1.5
17.1
38543-11-2230C/2hrs. 0.025" 227 17.1 673 2.4
270C/8hrs. 17.1
38543-11-4230C/2hrs. 0.025" 225 18.5 687 2.3
270C/l6hrs. 17.1
38543-11-6300C/8hrs. 0.025" 216 17.8 616 2.5
17.1
Example 7
In Example 7, VECTRATM L filaments were prepared as in Example 6, except
at higher denier. Draw-down was similar. Table VII summarizes the as-spun and
heat-treated properties of the filament formed from this polymer.
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Table VII
Heat Treated Properties for High Denier VectraTML Monofils
Sample Heat Treatment Orifice Den. Ten. Mod. Elong.
No. Size
Condition Draw-down d d
38538-25-1As-Spun (Control)0.015" 228 8.6 551 1.6
38543-I 230C/2 hr; 270C/8(6.2) 223 20.4 671 3.0
1-I hr
38538-26-6As-Spun (Control)0.015" 337 8.6 558 1.6
38543-00-1230C/2 hr; 270Cl8(6.2)
hr
38538-25-7As-Spun (Control)0.015" 444 8.8 543 1.7
38543-00-0230C/2hr; 270C/8hr(6.2)
38538-25-8As-Spun (Control)0.015" 545 8.8 544 1.7
38543-00-0230C/2hr; 270C/8 (6.2)
hr
38538-25-9As-Spun (Control)0.015" 656 8.5 520 1.7
38543-00-0230C/2 hr; 270C/8(6.2)
hr
38534-25-10As-Spun (Control)0.015" 745 8.1 510 1.7
38543-00-0230C/2 hr; 270C/8(6.2
hr
38538-26-IAs-Spun (Control)0.025" 233 7.5 564 1.5
38543-00-0230C/2hr;270C/8hr.(17.1) 227 17.1 673 2.4
38538-26-6As-Spun (Control)0.025" 350 7.9 580 1.5
38543-00-0230C/2hr; 270C/8hr(17.1)
38538-26-7As-Spun (Control)0.025" 467 8.0 551 1.6
38543-00-0230C/2hr; 270C/8hr(17.1)
38538-26-8As-Spun (Control)0.025" 578 7.8 534 1.6
38543-00-0230C/2hr; 270C/8hr(17.1)
38538-20-9As-Spun (Control)0.025" 676 7.3 530 1.6
38543-00-0230C/2hr; 270C/8 (17.1)
hr
38538-20-l0As-Spun (Control)0.025" 781 7.3 501 1.6
38543-00-0230C/2hr; 270C/8 (17.1)
hr
Example 8
Example 8 demonstrates that the heat treatment of filament wound directly on-
bobbin in accordance with one of the preferred embodiments of this invention.
To develop the on-bobbin heat treatment capabilities, a heat treatment setup
using a canister eduipped with rubber gaskets was built. A programmable forced
air
Precision oven with copper tubing running along the inside walls was used to
heat the
1o bobbins after it was placed and sealed in the canister. Nitrogen gas was
introduced
into the copper tubing at 60 to 100 SCFH, making sure that the nitrogen gas
penetrates the heat treatment package. The purge gas was heated as it passed
through
the oven tubing. The heated nitrogen was passed into the canister and flowed
from
the center of the bobbin outward. The nitrogen was then exhausted out of the
canister
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and out of the oven guaranteeing the removal of the reaction products which
otherwise could inhibit the property buildup.
The heat treatment bobbins, 6-inch in diameter and about 13-inch wide, was
constructed of perforated aluminum cylinders. The outside of the cylinders
were
covered with fiberfrax, a porous ceramic matting, to accommodate for the
shrinkage
of the monofilaments during heat treatment. For safety reasons (glass
particulate
containment), the fiberfrax was enclosed with polybenzimidazole (PBI) socks.
Based
on empirical findings, a permanent layer of VectranTM yarn wrapped on top of
the PBI
enclosure offered better heat treated properties. To improve package formation
to (dough) for the monofilament processing, aluminum flanges were also added
at each
end of the bobbins. For bobbin preparation, the as-spun monofilaments were
wound
on to the heat treatment bobbins at low tension by using a Leesona winder at
50
m/min. After heat treatment, the fiber was re-wound on to the final product
spool.
For on-bobbin heat treatment, it was found that winding the fiber at low
tension is essential for making high tensile properties. By using low rewind
tension,
low speed and fiber lubricant (finish or water), monofilaments with
outstanding
mechanical properties were obtained. The standard heat treatment process for
monofilaments formed according to the process of this invention is shown
below. The
initial dwell at 230 °C was added to allow the softening point to
increase and eliminate
2o fiber tapiness.
Heat Treatment Cycle:
(1) - Fast ramp to 230°C
(2) - Dwell a 230°C for two hours
(3) - Ramp O 15°C/hr. to 270°C
(4) - Dwell @ 270°C for 8 hours
(5) - Cool down to 100°C before opening oven.
Monofilaments of VECTRA A were spun at 300 m/min and an appropriate
draw-down to make a 220 denier. For physical property enhancement, the
filaments
were heat treated on the bobbin to make continuous heat treated monofilaments.
Low
3o tension during winding and rewinding is very important in the determination
of the
final properties. For this experiment, approximately 10 grams of tension was
considered as critical during winding on to the heat treatment bobbins in
order to

CA 02280627 1999-08-17
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achieve optimum properties while making a neat bobbin that can be heat treated
and
unwound without any difficulty. Tensions lower than 10 grams produced bobbins
in
which the fiber was falling of~'the bobbin and were difficult to unwound. The
physical
properties of samples rewound with 10 grams of tension @ 50 m/m is as follows:
Tenacity = 25.89 g/d; Elongation = 3.28% and Modulus = 660.1 g/d.
Example 9
Example 8 was repeated in Example 9 with the exception that the increased
rewound tension of 20 grams was employed. The physical properties of the heat
to treated monofilament are as follows:
Tenacity = 18.03 g/d; Elongation = 2.50% and Modulus = 650.8 g/d.
Example 10
Example 8 was repeated in this Example 10 with the exception that two as-
spun monofilament samples were taken-up directly (during spinning at 300
m/min.) on
to the heat treatment bobbins. The spinline tensions were measured as 10 and
20
grams with the physical properties shown below.
Sample No. 1: Sample as-spun to Leesona @ 300 m/m and 10 grams of tension:
Tenacity = 20.3 g/d; Elongation = 2.9%; Modulus = 663 g/d
Sample No. 2: Sample as-spun to Leesona @ 300 m/m and 20 grams of tension:
Tenacity = 15.6 g/d; Elongation = 2.2%; Modulus = 652 g/d
Examples 11
Comparison with a conventional rop cess.
Examples I and 2 were repeated in this Example 11, except that the high denier
VECTRAT'~ A polymer monofilaments were extruded using a water bath as the
quench
system. The extruded monofilaments were about 200 denier and were heat treated
3o using the same system and conditions as Example 2. The results in the
following Table
VIII, summarizing the as-spun and heat-treated properties of the filaments,
clearly
indicate that the water quenched monofilaments have inferior properties
relative to
those shown in Table II.
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TABLE VIII
Sample Heat Treatment Denier Tenacity Mod. Elong.
No.
Condition d d
38479-01-1Control, as-spun 221 6.7 502 1.58
38543-08-12 hr Preheat @ 218 12.5 588 2.21
230 C
2 hr hold 270
C
38543-08-22 hr Preheat a 220 112.6 530 2.27
230 C
2 hr hold r 270
C
Although the invention has been illustrated by certain of the preceding
examples, it is not to be construed as being limited thereby; but rather, the
invention
encompasses the generic area as hereinbefore disclosed. Various modifications
and
embodiments can be made without departing from the spirit and scope thereof.
I claim:
32