NON-WOVEN ARTICLES COMPRISED OF THERMOTROPIC LIQUID CRYSTAL POLYMER FIBERS AND METHOD OF PRODUCTION THEREOF

ARTICLES NON TISSES FORMES DE FIBRES POLYMERES A CRISTAUX LIQUIDES THERMOTROPES ET METHODE DE FABRICATION CONNEXE

English Abstract

ABSTRACT OF THE DISCLOSURE
Non-woven articles comprised of thermotropic liquid
crystal polymer fibers and a method of production thereof are
disclosed. Such non-woven articles exhibit desirable thermal
stability and chemical and solvent resistance. In addition, the
articles exhibit desirable multi-dimensional tensile strength and
modulus.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A non-woven article which exhibits desirable thermal
stability and chemical and solvent resistance comprised of fib-
ers of a polymer which is capable of forming an anisotropic
melt phase, said fibers being bonded together to an extent suffi-
cient to impart structural integrity to said article.
2. The article of claim 1 wherein said polymer is a
wholly aromatic polymer.
3. The article of claim 1 wherein said polymer is a
wholly aromatic polyester.
4. The article of claim 1 wherein said polymer exhibits
an inherent viscosity of at least 2.0 dl./g. when dissolved in
a concentration of 0.1 percent by weight in pentafluorophenol at
60°C.
5. The article of claim 1 wherein said polymer comprises
not less than about 10 mole percent of recurring units which
include a naphthalene moiety.
6. The article of claim 5 wherein said naphthalene moiety
of said wholly aromatic polymer is selected from the group con-
sisting of a 6-oxy-2-naphthoyl moiety, a 2,6-dioxynaphthalene
moiety, and a 2,6-dicarboxynaphthalene moiety.
7. The article of claim 1 wherein said polymer is capable
of forming an anisotropic melt phase at a temperature below
approximately 400°C.
- 27 -

8. The article of claim 1 wherein said polymer comprises
a melt processable wholly aromatic polyester which is capable
of forming an anisotropic melt phase and consists essentially
of the recurring moieties I, II, and III wherein:
I is <IMG> ,
II is <IMG> , and
III is <IMG> , and
wherein said polyester comprises approximately 30 to 70 mole
percent of moiety I and wherein at least some of the hydrogen
atoms present upon the rings optionally may be replaced by
substitution selected from the group consisting of an alkyl
group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon
atoms, halogen, phenyl, substituted phenyl, and mixtures there-
of.
9. The article of claim 8 wherein said polyester com-
prises approximately 40 to 60 mole percent of moiety I, approxi-
mately 20 to 30 mole percent of moiety II, and approximately 20
to 30 mole percent of moiety II.
10. The article of claim 1 wherein said polymer comprises
a melt processable wholly aromatic polyester which is capable
of forming an anisotropic melt phase and consists essentially
of the recurring moieties I and II wherein:
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and
I is <IMG>, and
II is <IMG> ,
wherein said polyester comprises approximately 10 to 90 mole,
percent of moiety I, and approximately 10 to 90 mole percent of
moiety II and wherein at least some of the hydrogen atoms
present upon the rings optionally may be replaced by substitu-
tion selected from the group consisting of an alkyl group of
1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon atoms,
halogen, phenyl, substituted phenyl, and mixtures thereof.
11. The article of claim 10 wherein said polyester com-
prises approximately 65 to 85 mole percent of moiety II.
12. The article of claim 10 wherein said polyester com-
prises approximately 15 to 35 mole percent of moiety II.
13. The article of claim 1 wherein said polymer comprises
a melt processable wholly aromatic polyester which is capable
of forming an anisotropic melt phase and consists essentially
of the recurring moieties I, II, and III wherein:
I is <IMG>
II is a dioxy aryl moiety of the formula ?O-Ar-O?
where Ar is a divalent radical comprising at least one aromatic
ring, and
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III is a dicarboxy aryl moiety of the formula ??-Ar'-??
where Ar' is a divalent radical comprising at least
one aromatic ring, and
wherein said polyester comprises approximately 10 to 90 mole
percent of moiety I, approximately 5 to 45 mole percent of moiety
II, and approximately 5 to 45 mole percent of moiety III and
wherein at least some of the hydrogen atoms present upon the
rings optionally may be replaced by substitution selected from
the group consisting of an alkyl group of 1 to 4 carbon atoms, an
alkoxy group of 1 to 4 carbon atoms, halogen, phenyl, substituted
phenyl, and mixtures thereof.
14. The article of claim 13 wherein said polyester
comprises approximately 20 to 80 mole percent of moiety I,
approximately 10 to 40 mole percent of moiety II, and approxi-
mately 10 to 40 mole percent of moiety III.
15. The article of claim 1 wherein said polymer com-
prises a melt processable wholly aromatic polyester which is
capable of forming an anisotropic melt phase and consists essen-
tially of the recurring moieties I, II, III and IV wherein:
I is <IMG> ,
II is <IMG> ,
III is a dioxy aryl moiety of the formula ?O-Ar-O?
wherein Ar is a divalent radical comprising at least one
aromatic ring, and
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IV is a dicarboxy aryl moiety of the formula ??-Ar'-??
where Ar' is a divalent radical comprising at least one
aromatic ring, and
wherein the polyester comprises approximately 20 to 40 mole
percent of moiety I, in excess of 10 up to about 50 mole percent
of moiety II, in excess of 5 up to about 30 mole percent of
moiety III, and in excess of 5 up to about 30 mole percent of
moiety IV and wherein at least some of the hydrogen atoms present
upon the rings optionally may be replaced by substitution
selected from the group consisting of an alkyl group of 1 to 4
carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
16. The article of claim 15 wherein said polyester
comprises approximately 20 to 30 mole percent of moiety I,
approximately 25 to 40 mole percent of moiety II, approximately
15 to 25 mole percent of moiety III and approximately 15 to 25
mole percent of moiety IV.
17. The article of claim 1 wherein said polymer
comprises a melt processable poly(ester-amide) which is capable
of forming an anisotropic melt phase and consists essentially of
the recurring moieties I, II, III and optionally IV wherein:
I is <IMG> ,
II is ??-Ar'-?? where A is a divalent radical comprising
at least one aromatic ring or a divalent trans-
-31-

cyclohexane radical;
III is ?Y-Ar-Z?, where Ar is a divalent radical
comprising at least one aromatic ring, Y is O, NH,
or NR, and Z is NH or NR, where R is an alkyl group
of 1 to 6 carbon atoms or an aryl group; and
IV is ?O-Ar'-O?, where Ar' is a divalent radical
comprising at least one aromatic ring;
and wherein said poly(ester-amide) comprises approximately 10 to
90 mole percent of moiety I, approximately 5 to 45 mole percent
of moiety II, approximately 5 to 45 mole percent of moiety III,
and approximately 0 to 40 mole percent of moiety IV and wherein
at least some of the hydrogen atoms present upon the rings
optionally may be replaced by substitution selected from the
group consisting of an alkyl group of 1 to 4 carbon atoms, an
alkoxy group of 1 to 4 carbon atoms, halogen, phenyl, substituted
phenyl, and mixtures thereof.
18. The article of claim 1 wherein said polymer has
been subjected to a heat treatment for a period of time and at a
temperature sufficient to increase the melting temperature of the
polymer between about 20 to 50 centigrade degrees.
19. The article of claim 18 wherein said polymer has
been subjected to a heat treatment after formation of said
article.
20. The article of claim 18 wherein said heat treat-
-32-

ment temperature ranges from about 10 to about 30 centigrade
degrees below the melting temperature of the polymer.
21. The article of claim 20 wherein said period of
time ranges from about 0.5 to about 200 hours.
22. The article of claim 21 wherein said period of
time ranges from about 1 to about 48 hours.
23. The article of claim 22 wherein said period of
time ranges from about 5 to about 30 hours.
24. The article of claim 18 wherein said heat treat-
ment occurs in a non-oxidizing atmosphere.
25. The article of claim 24 wherein said atmosphere is
substantially moisture-free.
26. The article of claim 24 wherein said heat treat-
ment occurs in a nitrogen atmosphere.
27. The article of claim 1 which is in the form of a
sheet.
28. The article of claim 1 which consists essentially
of fibers of a polymer which is capable of forming an anisotropic
melt phase.
29. The article of claim 1 wherein said polymer has a
-33-

melting temperature in excess of about 200°C.
30. The article of claim 29 wherein said polymer has a
melting temperature in excess of about 400°C.
31. The article of claim 1 wherein said fibers are
thermally bonded together.
32. The article of claim 1 wherein said fibers are bond-
ed together by means of an adhesive.
33. A method for forming a non-woven article in the
form of a web or sheet which exhibits desirable thermal stabil-
ity and chemical and solvent resistance comprised of fibers of
a polymer which is capable of forming an anisotropic melt
phase, said method comprising spray spinning said polymer in
the melt phase to form a multitude of discontinuous fibers and
collecting said fibers in the form of a web or sheet the fibres
being bonded together to an extend sufficient to impart
structural integrity to said article.
34. The method of claim 33 wherein said fibers are
collected on a screen.
35. The method of claim 33 wherein said fibers become
thermally bonded together as they are collected.
36. The method of claim 33 wherein said fibers are ad-
hesively bonded together subsequent to being collected.
37. The method of claim 33 wherein said polymer is a
- 34 -

wholly aromatic polymer.
38. The method of claim 33 wherein said polymer is a
wholly aromatic polyester.
39. The method of claim 33 wherein said polymer exhi-
bits an inherent viscosity of at least 2.0 dl./g. when dissolved
in a concentration of 0.1 percent by weight in pentafluorophenol
at 60°C.
40. The method of claim 33 wherein said polymer com-
prises not less than about 10 mole percent of recurring units
which include a naphthalene moiety.
41. The method of claim 40 wherein said naphthalene
moiety of said wholly aromatic polymer is selected from the group
consisting of a 6-oxy-2-naphthoyl moiety, a 2,6-dioxynaphthalene
moiety, and a 2,6-dicarboxynaphthalene moiety.
42. The method of claim 33 wherein said polymer is
capable of forming an anisotropic melt phase at a temperature
below approximately 400°C.
43. The method of claim 33 wherein said polymer com-
prises a melt processable wholly aromatic polyester which is
capable of forming an anisotropic melt phase and consists essen-
tially of the recurring moieties I, II, and III wherein:
I is <IMG> ,
-35-

II is <IMG> , and
III is <IMG> , and
wherein said polyester comprises approximately 30 to
70 mol percent of moiety I and wherein at least
some of the hydrogen atoms present upon the rings
optionally may be replaced by substitution selected
from the group consisting of an alkyl group of 1 to
4 carbon atoms, an alkoxy group of 1 to 4 carbon
atoms, halogen, phenyl, substituted phenyl, and
mixtures thereof.
44. The method of claim 43 wherein said polyester
comprises approximately 40 to 60 mole percent of moiety I,
approximately 20 to 30 mole percent of moiety II, and approxi-
mately 20 to 30 mole percent of moiety III.
45. The method of claim 33 wherein said polymer
comprises a melt processable wholly aromatic polyester which is
capable of forming an anisotropic melt phase and consists essen-
tially of the recurring moieties I and II wherein:
I is <IMG> , and
II is <IMG> ,
wherein said polyester comprises approximately 10 to 90 mole
-36-

percent of moiety I, and approximately 10 to 90 mole percent of
moiety II and wherein at least some of the hydrogen atoms present
upon the rings optionally may be replaced by substitution
selected from the group consisting of an alkyl group of 1 to 4
carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
46. The method of claim 45 wherein said polyester com-
prises approximately 65 to 85 mole percent of moiety II.
47. The method of claim 45 wherein said polyester com-
prises approximately 15 to 35 mole percent of moiety II.
48. The method of claim 33 wherein said polymer comprises
a melt processable wholly aromatic polyester which is capable
of forming an anisotropic melt phase and consists essentially
of the recurring moieties I, II, and III wherein:
I is <IMG> ,
II is a dioxy aryl moiety of the formula ?O-Ar-O?
where Ar is a divalent radical comprising at least one aro-
matic ring, and
III is a dicarboxy aryl moiety of the formula
??-Ar'-?? where Ar' is a divalent radical comprising at least
one aromatic ring, and
wherein said polyester comprises approximately 10 to 90 mole
percent of moiety I, approximately 5 to 45 mole percent of
moiety II, and approximately 5 to 45 mole percent of moiety
III and wherein at least some of the hydrogen atoms present
upon the rings optionally may be replaced by substitution
- 37 -

selected from the group consisting of an alkyl group of 1 to 4
carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
49. The method of claim 48 wherein said polyester com-
prises approximately 20 to 80 mole percent of moiety I, approxi-
mately 10 to 40 mole percent of moiety II, and approximately
10 to 40 mole percent of moiety III.
50. The method of claim 33 wherein said polymer comprises
a melt processable wholly aromatic polyester which is capable
of forming an anisotropic melt phase and consists essentially
of the recurring moieties I, II, III and IV wherein:
I is <IMG> ,
II is <IMG> ,
III is a dioxy axyl moiety of the formula ?O-Ar-O?
wherein Ar is a divalent radical comprising at least one aro-
matic ring, and
IV is a dicarboxy aryl moiety of the formula
??-Ar'-?? where Ar' is a divalent radical comprising at least
one aromatic ring, and
wherein the polyester comprises approximately 20 to 40 mole per-
cent of moiety I, in excess of 10 up to about 50 mole percent
of moiety II, in excess of 5 up to about 30 mole percent of
moiety III, and in excess of 5 up to about 30 mole percent of
moiety IV and wherein at least some of the hydrogen atoms pre-
sent upon the rings optionally may be replaced by substitution
- 38 -

selected from the group consisting of an alkyl group of 1 to
4 carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
51. The method of claim 50 wherein said polyester com-
prises approximately 20 to 30 mole percent of moiety I,
approximately 25 to 40 mole percent of moiety II, approximately
15 to 25 mole percent of moiety III and approximately 15 to 25
mole percent of moiety IV.
52. The method of claim 33 wherein said polymer comprises
a melt processable poly(ester-amide) which is capable of forming
an anisotropic melt phase and consists essentially of the
recurring moieties I, II, III and optionally IV wherein:
I is <IMG> ,
II is ??-A-?? where A is a divalent radical compris-
ing at least one aromatic ring or a divalent transcyclohexane
radical;
III is ?Y-Ar-Z?, where Ar is a divalent radical
comprising at least one aromatic ring, Y is O, NH, or NR, and
Z is NH or NR, where R is an alkyl group of 1 to
- 39 -

6 carbon atoms or an aryl group; and
IV is ?O-Ar'-O?, where Ar' is a divalent radical
comprising at least one aromatic ring;
and wherein said poly(ester-amide) comprises approximately 10 to
90 mole percent of moiety I, approximately 5 to 45 mole percent
of moiety II, approximately 5 to 45 mole percent of moiety III,
and approximately 0 to 40 mole percent of moiety IV and wherein
at least some of the hydrogen atoms present upon the rings
optionally may be replaced by substitution selected from the
group consisting of an alkyl group of 1 to 4 carbon atoms, an
alkoxy group of 1 to 4 carbon atoms, halogen, phenyl, substituted
phenyl, and mixtures thereof.
53. The method of claim 33 wherein said polymer is
subjected to a heat treatment for a period of time and at a
temperature sufficient to increase the melting temperature of the
polymer between about 20 to 50 centigrade degrees subsequent to
formation of said article.
54. The method of claim 53 wherein said heat treatment
temperature ranges from about 10 to about 30 centigrade degrees
below the melting temperature of the polymer.
55. The method of claim 54 wherein said period of time
ranges from about 0.5 to about 200 hours.
56. The method of claim 55 wherein said period of time
ranges from about 1 to about 48 hours.
-40-

57. The method of claim 56 wherein said period of time
ranges from about 5 to about 30 hours.
58. The method of claim 53 wherein said heat treatment
occurs in a non-oxidizing atmosphere.
59. The method of claim 58 wherein said atmosphere is
substantially moisture-free.
60. The method of claim 58 wherein said heat treatment
occurs in a nitrogen atmosphere.
61. The method of claim 33 wherein said polymer has a
melting temperature in excess of about 200°C.
62. The method of claim 61 wherein said polymer has a
melting temperature in excess of about 400°C.
-41-

Description

~46~3~Q
This application is related -to United States Patent
No. 4,395,307 and Canadian Patent Application Serial No. 453,672.
BACKGROUND OF THE INVE~TION
The present invention relates to non-woven articles
comprised of thermotropic liquid crystal polymer fibers.
Various conventional non-woven articles comprised of
polymeric materials have been employed for many purposes. For
example, non-woven articles have been employed as filters,
electrical insulation and reinforcement for resins. However,
such non-woven articles have frequently been found to not be
appropriate for use in a high temperature environment (e.g.,
in excess of about 200C) or in an environment where the
structure will come into contact with solvents or corrosive
chemicals. It is therefore desirable to provide non-woven
articles comprised of a
.
~, 2

polymeric material which is resistant to solvents or corrosive
ehemicals and also suitable for use at high temperatures.
It is known to those skilled in the art that fibers
comprised of lyotropic liquid crystal polymers have been employed
in the production of non-woven scrim sheets in conjunction with
polyester fibers which are not capable of forming an anisotropic
melt phase wherein the polyester fibers are thermally bonded to
the lyotropic liquid crystal polymer fibers.
It is also known to those sXilled in the art ~hat the
heat treatment of shaped articles of l iquid crystal polymers
increases the melting tempera~ure, molecular weight and mecha-
nical properties of the polymer. See~ for example, U.5. Patent
Nos, 3,975,487; 4~183,895; and 4,247,514.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to
provide non-woven articles which are resistant to thermal degra-
dation.
It is also an object of the present invention to pro-
vide non-woven articles which are resistant to solvent and
chemical degradation.
It is further an object of the present invention to
provide non-woven articles which exhibit desirable multi-
dimensional tensile strength and modulus.
In accordance with one aspect of the present invention,
there is thus provided a non-woven article which exhibits desir-
able thermal stability and chemical and solvent resistance
comprised of fibers of a polymer which is capable of forming an
ani~o~rop;.~ P~. s~;d fibers being bonded together to an
extent ~ufficient to impart structural integrity to said article.
--3--
__
.

In accordance with another aspect of the present inven~
tion, there is thus provided 2 method for forming a non-woven
article in the form of a web or sheet which exhibits desirable
thermal stability and chemical and solvent resistance comprised
of fibers of a polymer which is capable of forming an anisotropic
melt phase, said method comprising spray spinning said polymer in
the melt phase to form a multitude of discontinuous fibers and
collecting said fibers in the form of a web or sheet.
DETAILED DESCRIPTION OF THE INVENTION
Thermotropic liquid crys~al polymers are polymers which
are liquid crystalline (i.e., anisotropic) in the melt phase.
These polymers have been described by various terms, including
~liquid crystalline,n nliquid crystal" and ~anisotropic.~
Briefly, the polymers of this class are thought to involve a
parall~l ordering of the molecular chains. The state wherein the
molecules are so ordered is often referred to either as the
liquid crystal state or the nematic phase of the liquid crystal-
line material. These polymers are prepared from monomers which
are generally long, flat and fairly rigid along the long axis of
the molecule and commonly have chain-extending linkages that are
either coaxial or parallel.
Such polymers readily form liquid crystals (i.e., exhi-
bit anisotropic properties) in the melt phase. Such properties
may be confirmed by conventional polarized light techniques
whereby crossed polarizers are utilized. More specifically, the
anisotropic melt phase may be confirmed by the use of a Leitz
polarizing microscope at a magnification of 4~X with the sample
on a Leitz hot stage and under nitrogen atmosphere. The polymer
. ~

~' ~
~f~820
is optically anisotropic; i.e., it transmits light when examined
between crossed polarizers. Polarized light is transmitted when
the sample is optically anisotropic even in the static state.
Those ther~otropic liquid crystal polymers suitable for
use in the present invention include but are not limited to
wholly aromatic polyesters, aromatic-aliphatic polyesters, aroma-
tic polyazomethines, wholly and non-wholly aromatic poly(ester
amide)s and aromatic polyester-carbonates.
The wholly aromatic thermotropic liquid crystal
polymers are comprised of moieties which contribute at least one
aromatic ring to the polymer backbone and which enable the poly-
mer to exhibit anisotropic properties in the melt phase. Such
moieties include ~ut are not limited to aromatic diols, aromatic
amines, aromatic diacids and aromatic hydroxy acidsu Moieties
which may be present in the thermotropic liquid crystal polymers
employed in the present invention (wholly aromatic or non-wholly
aromatic) include but are not limited to the following:
.
_
~ ~C~
~ 0~'' ~~
E ~ ~ CH2-
~O_CH2_C~2-O~ ~ '
. _

~2~6i320
NH~ NH ~ ~ t NH ~
Preferably, the thermotropic liquid crystal polymers
which are employed comprise not less than about 10 mole percent
of recurring units which include a naphthalene moiety.
Preferred naphthalene moieties include 6-oxy-2-naphthoyl, 2,6-
dioxynaphthalene, and 2,6-dicarboxynaphthalene.
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 copolymers 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.
Aromatic polyazomethines and processes of preparing
the same are disclosed in the United States 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. Specific examples of such
polymers include poly(nitrilo-2-methyl-1,4-phenyl-enenitrilo-
ethylidyne-1,4-phenyleneethylidyne); polytnitrilo-2-methyl-1,4-
phenylenenitrilomethylidyne-1,4-phenylene-methylidyne); and
poly(nitrilo-2-chloro-1,4-phenylenenitrilomethylidyne-1,4-

2~
phenylene-methylidyne).
Aromatic polyester-car~onates are disclosed in United
States Patent Mo. 4,107,143. Examples of such polymers include
those consisting essentially o~ hydroxybenzoic acid units,
hydroquinone units, carbonate units, and aromatic carboxylic
acid units~
The liquid crystal polymers which are preferred ~or
use in the present invention include thermotropic wholly
aromatic polyesters~ Recent publications disclosing such poly-
esters include (a) Belgian Patent Nos. 828,935 and 828,936,
(b) Dutch Patent No. 7505551, (c) West German Patent
Nos. 2,520,819, 2,520,820, and 2,722,120, (d) Japanese Patent
Nos. 43-223, 2132-116, 3017-692, and 3021-293, (e) United
States Patent Nos. 3,991,013; 3,991,014; 4,057,597; 4,066,620;
4,075,262; 4,118,372; 4,146,702; 4,153,77g, 4,156,070;
4,159,365; 4,169,933, 4,181,792; 4,188;476; 4,201,856;
4,226,970; 4,232,1~3; 4,232,144; 4,238,600; 4,245,08~;
4,267,304; 4,424,496; and 4,269,965; and (f) United Kingdom
Application No. 2,002,404.
Wholly aromatic polymers which are preferred for
use in the present invention include wholly aromatic polyesters
and poly(ester-amide)s which are disclosed in commonly-assigned
United States Patent Nos. 4,067,852; 4,083,829; 4,130,545;
4,161,470; 4,184,996; 4,219,461; 4,238,599; 4,256,624;
4,279,803; 4,337,191; 4,299,756 and 4,330,457. I'he wholly
aromatic polymers disclosed therein typically are capable of
forming an anisotropic melt phase at a temperature below
approximately 400C, and preferably below approximately 350C.
The wholly aromatic polymers including wholly
aromatic polyesters and poly(ester-amide)s which are suitable
-- 7 --

~29~6B;2~3
for use in 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, hydroxylgroups,ester groups, acyloxy
groups, acid halides, amine groups, 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 the polymer particles are suspended
therein. A vacuum may be applied to facilitate removal of
volatiles formed during the final stage of the condensation
(e.g., acetic acid or water).
Commonly-assigned United States Patent No. 4,083,829,
entitled "Melt Processable Thermotropic Wholly Aromatic
Polyester," describes a slurry polymerization process which
may be employed to form the wholly aromatic polyesters which
are preferred for use in the present invention. According to
such a process, the solid product is suspended in a heat exchange
medium.
When employing either the melt acidolysis procedure
or the slurry procedure of United States Patent No. 4,083,829,
the organic monomer reactants from which the wholly 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~O The lower acyl groups pre-
ferably have frc~ about two to about our carbon atoms. Pre-
ferably, the aceta~e esters of organic ~onomer reactants are
provided.
Representative catalysts which optionally may be
employed in either th~ melt acidolysis procedure or in the slurry
procedure of U.S. Patent No. 4,083,829 include dialkyl tin oxide
(e.g., dibutyl tin oxide) ! diaryl tin oxide, titanium dioxide,
antimony trioxide~ alkoxy titanium silicates, I itanium alkoxides,
alkali and alkaline earth metal salts of carboxylic acids (e.g.,
zinc acetate3, the gaseous acid catalysts such as Lewis acids
(e.y., BF3), hydrogen halides ~e.g., HCl), etc. The quantity of
catalyst utilized typically is about O.OOl to l percent by weight
based upon the total monomer weight, and most commonly about O.Ol
to 0.2 percent by weight.
The wholly aromatic polymers suitable for use in the
present invention 1:end to be substantially insoluble in common
solvents and accordingly are not susceptible to solution proces-
sing. As discussed previously, they can be readily processed by
common melt processing techniques. Most suitable wholly aromatic
polymers are soluble in pentafluorophenol to a limited degree.
The wholly aromatic polyesters which are preferred for
use in the present invention commonly exhibit a weight average
molecular weight of about 2jO00 to 200,000, and preferably about
lO,000 to 50,000, and mo~t preferably about 20,000 to 25,000.
The wholly aromatic poly~ester-amide)s which are preferred com-
monly exhibit a molecular weight of about 5000 to 50,000 and
preferably about lO,000 to 30,000; e.g., 15,000 to l7,000. Such
molecular weight may be dete~;n~d b gel pe~e~t ion ~h~m~
.~ _

~Zf~ 320
graphy as well as by standard techniques not involving the
solutioning of the polymer, e.g., by end group determination
via infrared spectroscopy on compression molded films.
A]ternatively, light scattering techniques in a pentafluoro-
phenol solution may be employed to determine the molecular
weight.
The wholly aromatic polyesters and poly(ester-amide)s
additionally commonly exhibit an inherent viscosity (i.e.,
I.V.) of at least approximately 2.0 dl./g., e.g., approximately
2.0 to 10.0 dl./g., when dissolved in a concentration of 0.1
percent by weight in pentafluorophenol at 60C.
Especially preferred wholly aromatic polymers are
those which are disclosed in above-noted United States Patent
Nos. 4,161,470, 4,184,996, 4,219,461, 4,238,599, 4,256,624 and
4,330,457.
For the purposes of the present invention, the
aromatic rings which are included in the polymer backbones of
the polymer components employed in the present invention may
include substitution of at least some of the hydrogen atoms
present upon an aromatic ring. Such substituents include alkyl
groups of up to four carbon atoms; alkoxy groups having up to
four carbon atoms; halogens; and additional aromatic rings,
such as phenyl or substituted phenyl. Preferred halogens include
fluorine, chlorine, and bromine. Although bromine atoms tend
to be released from organic compounds at high temperatures,
bromine is more stable on aromatic rings than on aliphatic
chains, and therefore is suitable for inclusion as a possible
substituent on the aromatic rings.
The wholly aromatic polyester which is disclosed in
United States Patent No. 4,161,470 is a melt processable wholly
aromatic
-- 10 --

dr~
polyester capable of forming an anisotropic melt phase at a tem-
perature below approximately 350C. The polyester consists
essentially of the recurring moieties I and II wherein:
I is ~ and
II is ~ ~ c~ .
The polyester comprises approximately 10 to 90 mole percent of
moiety I, and approximately 10 to 90 mole percent of moiety II.
In one embodiment, moiety II is present in a concentration of
approximately 65 to 85 mole percent, and preferably in a con-
centration of approximately 70 to 80 mole percent, e.g~, approxi-
mately 75 mole percent. In another embodiment, moiety II is
present in a lesser proportion of approximately 15 to 3~ mole
percent, and preferably in a concentration of approximately 20 to
30 mole percent. In addition, at least some of the hydrogen
atoms present upon the rings optionally may be replaced by sub-
stitution selected fra~ the group consisting of an alkyl group of
1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon atoms,
halogen, phenyl, substituted phenyl, and mixtures thereof.
The wh~lly aromatic polyester which is disclosed in
UOS~ Patent ND. 4,184,996 is a melt processable wholly aromatic
polyester capable of forming an anisotropic melt phase at a tem-
perature below approximately 325C. The polyester consists
essentially of the recurring moieties I, II, and III wherein;
l~s ~-'?~~
s~

~LZ4~GB20
II is ~ I ~ , and
III is
The polyester comprises approximately 30 to 70 mole percent of
moiety I. The polyester preferably comprises approximately 40 to
60 mole percent of moiety I, approximately 20 to 30 mole percent
of moiety II~ and approximately 20 to 30 mole percent of moiety
III. In addition, at least some of the hydrogen atoms present
upon the rings optionally may be replaced b~ substitution
selected from the group consisting of an alkyl group of 1 to 4
carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
The wholly aromatic polyester which is disclosed in
U.S. Patent No. 4,238,599 is a melt processable polyester capable
of forming an anisotropic melt phrase at a temperature no higher
than approximately 320C. consisting essentially of the recurring
moieties I, II, III and IV wherein:
Iis `E'~'l~ ,
II is ~H~ H H ~ ~0~
III is ~ and
-12-
--

~Z4~21~
E~
IV is ~ , where
R is methyl, chloro, bromo, or mixtures thereof, and is
substituted for a hydrogen atom present upon the aro-
matic ring,
and wherein said polyester ~omprises approximately 20 to 60 mole
percent of moiety I, approximately 5 to 18 mole percent of moiety
II, approximately 5 to 35 mole percent of moiety III, and
approximately 20 to 40 mole percent of moiety IY. The polyester
preferably comprises approximately 35 to 45 mole percent of
moiety I, approximately 10 to 15 mole percent of moiety II,
approximately 15 to 25 mole percent of moiety III, and approxi
mately 25 to 35 mole percent of moiety IV, with the proviso that
the total molar concentration of moieties II and III is substan-
tially identical to that of moiety IV. In addition, at least
some of th~ hydrogen atoms present upon the rings optionally may
be replaced by substitution selected from the group consisting of
an alkyl group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4
carbon atoms, halogen, phenyl, substituted phenyl, and mixtures
thereof. This wholly aromatic polyester commonly exhibits an
inherent viscosity of at least 2.0 dl./g., e.g., 2.0 to 10.0
dl./g., when dissolved in a concentration of 0.1 weight/volume
percent in pentafluorphenol at 60C.
The polyester disclosed in U.S. Patent No. 4,219,461 is
a melt processable wholly aromatic polyester which is capable of
forming an anisotropic melt phase at a temperature below approxi-
mately 320C. The polyester consists essentially of the
recurring moieties I, II, III, and IV wherein:
-13-

~ 6820
I is
II i~ ~ c
III is a dioxy aryl moiety of the formula ~O-Ar-O~
wherein Ar is a divalent radical comprising at least,
one aromatic ring, and
o
IV is a dicarboxy aryl moiety of the formula ~C-Ar'-C~
where Ar' is a divalent radical comprising at least
one aromatic ring, and
wherein the polyester ~omprises approximately 20 to 40 mole per-
cen~ of moiety I, in excess of 10 up to about 50 mole percent of
moiety II, in excess of 5 up to about 30 mole percent of moiety
III, and in excess of 5 up to about 30 mole percent of moiety
IV. The polyester preferably comprises approximately 20 to 30
(e.g., approx~mately 25) mole percent of moiety I, approximately
25 to 40 (e.g., approximately 35) mole percent of moiety II,
approximately 15 to 25 (e.g. approximately 20) mole percent of
moiety III, and approximately 15 to 25 (e.g., approximately 20)
mole percent of moiety IV. In addition, at least some of the
hydrogen ato~.s present upon the rings optionally may be replaced
by substitution selected from the group consisting of an alkyl
group of 1 to 4 carbon atoms, an alkoxy group of 1 to 4 carbon
atoms, halogen, phenyl, substituted phenyl, and mixtures
thereof.
Moieties III and IV are preferably symmetrical in the
sense that the divalent bonds which join these moieties to other
-14-
,~_

~ I ~
2~
moieties in the main polymer chain are symmetrically disposed on
one or more aromatic rings ~e.g., are para to each other or
diagonally disposed when present on a naphthalene ring)~ How-
ever~ non-symmetrical moieties, such as those derived from
resorcinol and isophthalic acid, may also be used.
Preferred moieties II I and IV are se$ forth in above-
no~ed U~S. Patent No. 4,219,461. The preferred dioxy aryl moiety
III is:
_ ~~
and the preferred dicarboxy aryl moiety IV is:
~T{~~ .
The polyester disclosed in U.S. Patent No. 4,256,624 is
a melt processable wholly aromatic polyester which is capable of
forming an anisotropic melt phase at a temperature below approxi-
mately 400C. The polyester consists essentially of the
recurring moieties I, II, and III wherein:
I is ~ ~ ~ ,
II is a dioxy aryl moi^'y of the f~rmul~ Ar~ Yh~.-e
-15-

~' ~
Ar is a divalent radical comprising at least one
aromatic ring, and
III is a dicarboxy aryl moiety of the formula ~C-Ar'-C~
where Ar' is a divalent radical comprising at least
one aromatic ring, and
wherein the polyester comprises approximately 10 to 90 mole per-
cent of moiety I, approximately 5 to 4~ mole percent of moiety
II, and approximately 5 to 45 mole percent of moiety III. The
polyester preferably cQmprises approximat~ly 20 to 80 mole
percent of moiety I, approximately 10 to 40 mole percent of
moiety II, and approximately 10 to 40 mole percent of moiety
III. The polyester more preferably comprises approximately 60 to
80 mole percent of moiety I, approximately 10 to 20 mole percent
of moiety II, and approximate~y 10 to 20 mole percent of moiety
III. In addition, at least some of the hydrogen atoms present
upon the rings opt:ionally may be replaced by substitution
selected from the group consisting of an alkyl group of 1 to 4
carbon atoms, an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
As with moieties III and IV of the polyester disclosed
in U.S. Patent No. 4,219,461, moieties II and III of the poly-
ester described immediately above may be symmetrical or nonsym-
metrical, but are preferably symmetrical.
Preferred moieties ~I and III are set forth in above-
noted U.S. Patent No. 4j256,624. The preferred dioxy aryl moiety
II is:
-16-

320
~ o _~o~ ,
and the preferred dicarboxy aryl moiety III is:
~:~ t
United States Patent No. 4,330,457 discloses a melt
processable poly(ester-amide) which is capable of forming an
anisotropic melt phase at a temperature below approximately
400C. The poly(ester-amide) consists essentially of the
recurring moieties I, II, III and optionally IV wherein:
I is ¦ ~ C ~
II is ~C-A-C~, where A is a divalent radical comprising
at least one aromatic ring or a divalent transcyclohexane
radical;
III is ~Y-Ar-Z~, where Ar is a divalent radical com-
prising at least one aromatic ring, Y is O, NH, or NR, and Z
is NH or NR, where R is an alkyl group of 1 to 6 carbon atoms
or an aryl group; and
IV is ~O-Ar'-O~, where Ar' is a divalent radical com-
prising at least one aromatic ring;
- 17 -

~2~6~
and wherein said poly(ester-amide) comprises approximately 10
to 90 mole percent of moiety I, approximately 5 to 4S mole
percent of moiety II, approximately 5 to 45 mole percent of
moiety III, and approximately O to 40 mole percent of moie-ty
IV. In addition, at least some of the hydrogen atoms present
upon the rings optionally may be replaced by subs-titution
selected from the group consisting of an alkyl group of 1 to
4 carbon atoms~ an alkoxy group of 1 to 4 carbon atoms, halogen,
phenyl, substituted phenyl, and mixtures thereof.
lQ Preferred moieties II, III and IV are set forth in
above-noted United States Patent No. 4,330,457. The preferred
dicarboxy aryl moiety II is:
O O
_ ~ _ ,
the preferred moeity III is:
t ~1 ~ O ~ or t N~
and the preferred dioxy aryl moiety IV is:
;. - 18 -

-- :~ - o
The non-woven articles o the present invention are
comprised of fibers o thermotropic liquid crystal polymers and
may be prod~ced in a variety of ways. For example, a thermotro-
pic liquid cxystal polymer may be spray spun onto a web or screen
to provide a random ~rray of polymeric fibers. In the alterna-
tive, melt spun fibers of a thermotropic liquid crystal polymer
cut to appr~priately short lengths can be slurried with a liquid
which is a non-solvent for the polymer (e~g., water) and subse-
quently filtered (or wet-laid) onto a web ox screen to provide a
random (i~e., multi-dimensional ) array of fibers.
The thus-produced random array may then be subjected to
a suitable thermal bonding or heat pressing step at a suitable
t~mperature to ~ond the fibers together and impart the desired
structural integrity thereto. That is, the article at a minimum
will support its own weight and preferahly can be pulled apart
only with difficulty. In such a process the fibers are heated
and pressed together for a period of time and at a pressure suf-
ficient to at least bond the fibers together at the cross-over
points. Such fusion bonding does not result in any significant
loss of orientation (and accordingly, loss of strength) since the
polymer of which the fibers is ~omprised forms an anisotropic
melt phase. Such a characteristic is in direct contrast to con-
ventional thermoplastic polymers which do not form an anisotropic
melt phase and which readily lose their orientation upon being
_~ g_

~L~f~
heated to temperatures in excess of their melting temperature.
This is also in contrast to lyotropic liquid crystal polymers
which cannot be fusion bondedO
It should be noted ~hat if the spray spun fibers are
not allowed to cool sufficiently prior to being deposited on the
web, the fibers will beco~e bonded together as they collect upon
the web or ficreen and a formal hea~ pressing step will not he
required. Polymers which are capable of forming an anisotropic
melt phase are particularly suited for use in such a method since
the pvlymer retains its orientation upon being spun and collected
in the form of a web or sheet. The spray-spun fibers can thus be
thermally bonded together to form a non-woven article having the
desired degree of structural integrity withQut exhibiting a
significant loss of orientation (and strength) as a result of
being bonded together in the melt phase.
The above-described spray spinning and slurry filtering
production processes are conventional processes for the produc-
tion of non-woven articles and are well within the knowledge of
one skilled in the art.
The fibers may also be bonded together by means of
adhesives such as hermoplastic or thermosetting resins, epoxies,
water soluble adhesives such as casine, guar gum, or polyacrylic
acid, solvent-based adhesives, and emulsion or latex based adhe-
sives such as styrene/butyl/acrylic copolymer systems~ The
adhesives may be coated onto the web or array of thermotropic
liquid crystal fibers by use of kiss rolls. In the alternative,
the adhesives may be sprayed upon or deposited upon the web by
known emulsion techniques (for use with wet laid paper). The use
of adhesives in such methods is known and will not be discussed
20-

~ ` ~
in greater detail herein~
The non-woven articles of the present invention possess
many advantageous characteristics due to the presence of thermo-
tropic liquid crystal polymers therein. That is, ~ince liquid
crystal polymers are fully drawn and highly oriented as spun, the
fibers which comprise the non-woven articles of the presen~
invention possess relatively high tensile strength and modulus.
Accordingly, non-woven articles comprised of such fibers simi-
larly exhibit relatively high tenacity and modulus.
In addition, ~he article exhibits such tensile s~rength
and modulus in a multi-dimensicnal manner due to the multi-
dimensional orientation of the fibers within the structure.
The non-woven articles also benefit from other physical
characteristics of thermotropic liquid crystal polymers such as
resistance to chemical corrosion or solvation and high tempera-
ture stability due to the high melting temperatures of the
fibers. For instance, the melting temperature of the polymer is
preferably in excess of 200C. and most preferably in excess of
400C. Such articles thus are well suited for use as filters in
high temperature and~or otherwise destructive environments which
would tend to degrade conventional filters such as treatment of
stack gases from electrical generating plants. The articles can
also be used to filter a variety of liquids without dissolving or
being subject to corrosion or other degradative chemical pro-
cesses.
A particularly interesting use for such non-woven
articles i5 as the matrix material in ballistics pro~ection wear-
ing apparrel. Due to the high tenacity and modulus exhibited by
the liquid crystal polymers which comprise the non-w~ven
-21-
~ ,~

p~ ! ~
~2~
articles, such articles are readily adaptable to such a use~ In
order to take full advanta~e of the properties of the fibers of
thermotropic liquid crystal polymers, it is preferred that the
non-woven article cvmprise at least a major portion ~e.q., at
least about 50 percent by weight) of the fibers and preferably
consists essentially of such fibers. In a most preferred embodi-
ment the article consists entirely of fibers of liquid crystal
polymers.
The mechanical properties of the non-woven articles
produced in accordance with the present invention can be improved
by subjecting the articles to a heat treatment following forma-
tion thereof. me heat treatment improves the properties of the
article by increasing the molecular weight of the liquid crystal-
line polymer which comprises the fibers present within the
article and increasing the degree of crystallinity thereof while
also increasing the melting temperature of the polymer. Such
heat treatment can also serve to bond the fibers together.
The articles may be thermally treated in an inert
atmosphere (e.g., nitrogen, carbon dioxide, argon, helium) or
alternatively, in a flowing oxygen-containing atmosphere (e.g.,
air). The use of a non-oxidizing substantially moisture-free
atmosphere is preferred to avoid the possibility of thermal
degradation. For instance, the article may be brought to a tem-
perature approximately 10 to 30 centigrade degrees below the
melting temperature of the liquid crystal polymer, at which tem-
perature the fibers remain a solid object. It is preferable for
the temperature of the heat treatment to be as high as possible
without e~ualing or exceeding the melting temperature of the
polymer. It is most preferable to gradually increase the tem-
-22-

pera~ure o~ heat treatment in accordance with the increase of the
melting temperature of the polymer during heat treatment.
The duration of the heat treatment will commonly range
frcm a few minutes to a number of days~ e.g , from 0.5 to 200
hours, or more. Prefera~ly, the hea~ treatment is conducted for
a time of 1 to 48 hours and typically from about ~ to 30 hours.
Generally, ~he duration of heat treatment varies -~
depending upon the heat treatment temperature; that is, a shorter
treatment time is required as a higher treatment temperature is
used. Thus, the duration of the heat treatment can be shortened
for higher melting polymers, since higher heat treatment tempera-
tures can be applied withou~ melting the polymer.
Preferably, the heat treatment i5 conducted under con-
ditions sufficient to increase the melting temperature of the
polymer at least 10 centigrade degrees. Most preferably, the
melting temperature of the liquid crystal polymer is increased
from between about 20 to about 50 centigrade degrees as a resul~
of the heat treatment. The amount of increase which is obtained
is dependent upon the temperature used in the heat treatment,
with higher heat treatment temperatures giving greater increases.
Similar advantages can also be obtained by heat treat~
ment of the fibers prior to their incorporation into the non-
woven structure. It is, however, preferable to heat treat the
structure subsequent to its formation since ~he thermal bonding
and heat treatment steps can then be combined.
It should be noted at this time that reference herein
to a temperature below which a specific polymer may exhibit
aniso~ropic properties in the melt phase is intended to refer to
the ~emperature below which the polymer exhibit~ su~h pr~perties
-23-

~ a
"~
prior to any heat treatment thereof.
The chemical resistance of the polymer also increases
with heat treatmen~ and the solubility into pent fluorophenol,
one of the rare ~ol~ents for thermotropic liquid crystal poly-
mers, continuously decreases with increasing heat reatment time
and eventually the material will not dissolve even minimally
~such as in amounts of Ool pexcent by weight). Accordingly,
reference herein to solution characteristics of specific polymers
is intended to refer to such characteristics prior to any heat
treatment of the polymer~
The invention is additionally illustrated in connection
with the following Example~ which are to be considered as illus-
trative of the present inventionr It should be understood,
however, that the invention is not limited to the ~pecific
details of the Examples.
-24-
.,--~

~Z~ Q
EXAI/IPLE 1
As-spun fibers comprised of a thermotropic liquid
crystal polymer consisting of 40 molc percent of a p-oxybenzoyl
moiety and 60 mole percen~ of a 6-oxy-2-naphthoyl moiety are
provided having a denier per filament ranging from about 7 to
10. The fibers are chopped into microfibers ranging in length
from about 1/4 to 3~8 inch in length and admixed with water to
form a slurry. The slurry is well stirred to achieve a uniform
dispersal of the chopped fibers in the slurry.
The slurry admixture is poured into a tall Buchner
filter funnel containing a disk of filter paper. The water is
drained off with the aid of a vacuum leaving a random mat of
chopped fibers upon the filter paper. The web is carefully
removed from contact with the fiiter paper and dried. The dried
web of fibers demonstrates weak structural integrity ~i.e., it
barely supports its own weigh~ and is easily pulled apart).
The fibers are bound together by pressing the web
between two heated plates whereupon the web is heated to approxi-
mately 275C. The web is sandwiched between Kapton release
films to prevent the web from sticking to the plates. The web
subsequent to hot pressing exhibits substantial structural
integrity and is pulled apart only with difficulty while also
exhibiting textile-like draping characteristics.
EXAMPLE 2
Pellets ccmprised of a thermotropic liquid crystal
polymer consisting of 40 mole percent of a p-oxybenzoyl moietY
-25-

0
and 60 mole percent of a 6-oxy-2-naphthoyl m~iety are dried for
24 hours in a warm vacuwn oven~ The pellets are then introduced
into the hopper of a spray spinning unit with the temperature of
the polymer subsequently being raised to 360C wi~hin ~he
extruder section o the unit to provide a polymer melt. The melt
is then spun from a 0.16 mill jet into an air attenuation section
of the spray spinning unit where the melt is exposed to the air
drag of three impinging unheated air jets and reduced to a f iber
of about 50 denier per filament. The spun fiber is collected as
a non-bonded mat upon a wire screen located approximately 30
inches from the jet.
Air heated to between about 200-500C. is also employed
to attenuate ~he melt which results in the production of a mat of
fibers which are bonded together at their cross-over points.
This bonded mat is formed by collecting the fibers on a screen
located approximately 12 to 16 inches from the jet.
The princ:iples, preferred embodiments and modes of
operation of the present invention have been described in the
foregoing specification. The invention which is intended to be
protected herein, however, is not to be construed as limited to
the particular forms disclosed, since these are to be regarded as
illustrative rather than restrictive. Variations and changes may
be made by those skilled in the art without departing from the
spirit of the invention.
-2~-
_