Thermotropic liquid crystal polymer pulp and method of preparation thereof wherein said polymer comprises recurring units which contain a 2,6-dioxyanthraquinone moiety

A novel pulp is provided comprised of fibrils of a thermotropic liquid crystal polymer which comprises recurring units which contain a 2,6-dioxyanthraquinone moiety. Materials comprised of thermotropic liquid crystal polymers which contain such a moiety are readily broken up to form a pulp comprised of fibrils which can be incorporated into a variety of articles such as papers.

CROSS-REFERENCE TO RELATED APPLICATIONS 
This application is related to U.S. patent applications (1) Ser. No. 
319,525, filed Nov. 9, 1981, of Alan Buckley and Gordon W. Calundann 
entitled "Non-Woven Articles Comprised of Thermotropic Liquid Crystal 
Polymer Fibers;" (2) Ser. No. 319,524, filed Nov. 9, 1981, of Alan 
Buckley, Gordon W. Calundann and John R. Kastelic entitled "High 
Performance Papers Comprised of Fibrils of Thermotropic Liquid Crystal 
Polymers;" and (3) Ser. No. 319,522, filed Nov. 9, 1981, of Alan Buckley, 
Gordon W. Calundann and John R. Kastelic entitled "Thermotropic Liquid 
Crystal Polymer Pulp and Method of Production Thereof." 
BACKGROUND OF THE INVENTION 
The present invention is directed to a pulp comprised of fibrils of 
thermotropic liquid crystal polymers. 
Various articles such as papers comprised of polymeric materials have been 
employed for many purposes. For example, such structures have been 
employed as filters and electrical insulation, etc. However, such articles 
are frequently not appropriate for use in a high temperature environment 
(e.g., temperatures in excess of about 200.degree. C.) or in an 
environment where the structure will come into contact with corrosive 
chemicals or solvents. It is therefore desirable to provide articles 
comprised of a polymeric material which is resistant to solvents or 
corrosive chemicals and suitable for use at high temperatures. 
It has been recently found that thermotropic liquid crystal polymers can be 
advantageously used in non-woven articles and papers to impart the desired 
thermal and chemical resistance thereto. See, for example, the 
above-referenced related U.S. Patent applications (1) and (2). 
As noted in the above-referenced application (3), a pulp comprised of 
fibrils of thermotropic liquid crystal polymers can be provided by 
masticating various articles comprised of such polymers. While such 
articles can be broken up without too much difficulty due to the high 
degree of orientation of the polymer within the article, it has been found 
that a significant amount of time and energy is frequently required to 
provide a pulp comprised of submicron size particles (e.g., fibrils) of 
thermotropic liquid crystal polymers. 
It is therefore desirable to provide a thermotropic liquid crystal polymer 
which can readily be broken up into submicron size particles to form a 
pulp suitable for use in articles such as papers. 
It is also desirable to provide a method by which a thermotropic liquid 
crystal polymer can be readily broken up into submicron size particles to 
provide a pulp suitable for use in articles such as papers. 
It is also known to those skilled in the art that the heat treatment of 
shaped articles of liquid crystal polymers increases the melting 
temperature, molecular weight and mechanical properties of the polymer. 
See, for example, U.S. Pat. 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 a method by 
which a thermotropic liquid crystal polymer can be readily broken up into 
submicron size particles. 
It is also an object of the present invention to provide a pulp produced by 
such a method. 
In accordance with one aspect of the present invention, there is thus 
provided a method for providing a pulp comprised of fibrils of a polymer 
which exhibits desirable thermal stability and chemical and solvent 
resistance comprising the steps of: 
providing a shaped article comprised of a polymer capable of forming an 
anisotropic melt phase which comprises not less than about 5 mole percent 
of recurring units which include a 2,6-dioxyanthraquinone moiety; and 
masticating said shaped article to form fibrils comprised of said polymer. 
In accordance with another aspect of the present invention, there is 
provided a pulp comprised of fibrils of a polymer which is capable of 
forming an anisotropic melt phase and which comprises not less than about 
5 mole percent of recurring units which include a 2,6-dioxyanthraquinone 
moiety. 
DETAILED DESCRIPTION OF THE INVENTION 
Thermotropic liquid crystal 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," "liquid 
crystal" and anisotropic." Briefly, the polymers of this class are thought 
to involve a parallel 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 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., exhibit 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 
40.times. with the sample on a Leitz hot stage and under nitrogen 
atmosphere. The polymer 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. 
These thermotropic liquid crystal polymers suitable for use in the present 
invention are those polymers which comprise not less than about 5 mole 
percent of recurring units which include a 2,6-dioxyanthraquinone moiety. 
Such polymers may include but are not limited to wholly aromatic 
polyesters, aromatic-aliphatic polyesters, aromatic polyazomethines, 
wholly and non-wholly aromatic poly(ester-amide)s and aromatic 
polyestercarbonates. Recurring units which contain the 
2,6-dioxyanthraquinone moiety are preferably present in amounts ranging 
from about 5 to about 25 mole percent, and most preferably, from about 5 
to about 15 mole percent. 
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 polymer to exhibit anisotropic properties in 
the melt phase. Such moieties include but are not limited to aromatic 
diols, aromatic amides, aromatic diacids and aromatic hydroxy acids. 
Moieties (in addition to 2,6-dioxyanthraquinone) which may be present in 
the thermotropic liquid crystal polymers employed in the present invention 
(wholly or non-wholly aromatic) include but are not limited to the 
following: 
##STR1## 
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 U.S. Pat. No. 4,224,433 and U.S. Pat. 
No. 4,341,688. Additional wholly aromatic polyesters which are suitable 
for use in the present invention are disclosed in U.S. Pat. No. 4,188,476. 
The disclosures of all of the above-identified U.S. patents and 
applications are herein incorporated by reference in their entirety. 
The wholly aromatic polymers including wholy aromatic polyesters and 
poly(ester-amide)s which are suitable 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, 
hydroxyl groups, 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 said 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., acetate acid or water). 
Commonly-assigned U.S. Pat. No. 4,083,829, entitled "Melt Processable 
Thermotropic Wholly Aromtic 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. The 
disclosure of this patent is herein incorporated by reference in its 
entirety. 
When employing either the melt acidolysis procedure or the slurry procedure 
of U.S. Pat. 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). The lower acyl 
groups preferably have from about two to about four carbon atoms. 
Preferably, the acetate esters of organic monomer reactants are provided. 
Representative catalysts which optionally may be employed in either the 
melt acidolysis procedure or in the slurry procedure of U.S. Pat. No. 
4,083,829 include dialkyl tin oxide (e.g., dibutyl tin oxide), diaryl tin 
oxide, titanium dioxide, antimony trioxide, alkoxy titanium silicates, 
titanium alkoxides, alkali and alkaline earth metal salts of carboxylic 
acids (e.g., zinc acetate), the gaseous acid catalysts such as Lewis acids 
(e.g., BF.sub.3), hydrogen halides (e.g., HCl), etc. The quantity of 
catalyst utilized typically is about 0.001 to 1 percent by weight based 
upon the total monomer weight, and most commonly about 0.01 to 0.2 percent 
by weight. 
The aromatic polymers suitable for use in the present invention tend to be 
substantially insoluble in common solvents and accordingly are not 
susceptible to solution processing. 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 
extent. 
The wholly aromatic polyesters which are preferred for use in the present 
invention commonly exhibit a weight average molecular weight of about 
2,000 to 200,000, and preferably about 10,000 to 50,000, and most 
preferably about 20,000 to 25,000. The wholly aromatic poly(ester-amide)s 
which are preferred commonly exhibit a molecular weight of about 5000 to 
50,000 and preferably about 10,000 to 30,000; e.g., 15,000 to 17,000. Such 
molecular weight may be determined by gel permeation chromatography as 
well as by other standard techniques not involving the solutioning of the 
polymer, e.g., by end group determination via infrared spectroscopy on 
compression molded films. Alternatively, light scattering techniques in a 
pentafluorophenol 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 1.0 
dl./g., e.g., approximately 1.0 to 10.0 dl./g., when dissolved in a 
concentration of 0.1 percent by weight in pentafluorophenol at 60.degree. 
C. 
Especially preferred wholly aromatic polymers are those which are disclosed 
in above-noted U.S. Pat. No. 4,224,433 and in U.S. Pat. No. 4,341,688. 
For the purpose 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 and 
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 polyester disclosed in U.S. Pat. No. 4,224,433 is a melt processable 
wholly aromatic polyester which is capable of forming an anisotropic melt 
phase at a temperature below approximately 375.degree. C. The polyester 
consists essentially of the recurring moieties I, II and III wherein: 
##STR2## 
where X is selected from at least one member of the group consisting of 
(a) 1,3-phenylene radicals which optionally are replaced with up to 75 
mole percent of 1,4-phenylene radicals based upon the total concentration 
of 1,3-phenylene and 1,4-phenylene radicals present in the polyester, 
##STR3## 
and wherein the polyester comprises approximately 15 to 30 mole percent of 
moiety I, approximately 35 to 70 mole percent of moiety II, and 
approximately 15 to 30 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 conisting 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. 
U.S. Pat. No. 4,341,688 discloses a melt processable poly(ester-amide) 
capable of forming an anisotropic melt phase at a temperature below 
approximately 400.degree. C. consisting essentially of recurring moieties 
I, II, III, and IV wherein: 
##STR4## 
where X is selected from at least one member of the group consisting of 
(a) 1,3-phenylene radicals which optionally are replaced with up to 75 
mole percent of 1,4-phenylene radicals based upon the total concentration 
of 1,3-phenylene and 1,4-phenylene radicals present in moiety III, 
##STR5## 
(h) a divalent aliphatic carbocyclic radical, and (i) mixtures of the 
foregoing; and 
IV 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, 
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, and wherein moiety I is present in a concentration within the 
range of approximately 5 to 35 mole percent, moiety II is present in a 
concentration within the range of approximately 20 to 80 mole percent, 
moiety III is present in a concentration within the range of approximately 
10 to 40 mole percent, and moiety IV is present in a concentration within 
the range of approximately 5 to 35 mole percent, with the total molar 
concentration of moieties I and IV being substantially equal to the molar 
concentration of moiety III. Preferably, moiety I is present in a 
concentration in the range of approximately 5 to 30 mole percent, moiety 
II is present in a concentration in the range of approximately 30 to 70 
mole percent, and moiety III is present in a concentration in the range of 
approximately 15 to 35 mole percent. 
The pulp of the present invention is comprised of fibrils of thermotropic 
liquid crystal polymers (i.e., polymers which are capable of forming an 
anisotropic melt phase) and which comprise not less than about 5 mole 
percent of recurring units which include a 2,6-dioxyanthraquinone moiety. 
It has been surprisingly and unexpectedly found that fibrils of submicron 
size can be obtained from thermotropic liquid crystal polymers which 
contain the 2,6-dioxyanthraquinone moiety with significantly less energy 
input and over a shorter period of time than is required when fibrils are 
produced from thermotropic liquid crystal polymers which do not contain 
such a moiety. 
The fibrils may be produced by several methods including mechanically 
masticating shaped articles (such as as-spun fibers) of thermotropic 
liquid crystal polymers. Since the as-spun fibers are highly oriented 
along their longitudinal axis, the fibers are able to withstand much less 
stress along the transverse axis as opposed to along the longitudinal 
axis. Accordingly, the fibers break up length-wise into much narrower 
fibrils as they are masticated to form a pulp. Such articles are 
preferably masticated while in the form of an aqueous slurry. The term 
"masticating" as used herein is intended to include various mechanical 
processes such as grinding whereby the shaped article is subjected to 
crushing and/or shearing forces of sufficient magnitude to break up the 
shaped article into fibrils. Preferably, the shaped article is masticated 
for a sufficient period of time to ensure that a major portion of the 
fibrils (based on the number of fibrils present) are of submicron size 
(i.e., less than one micron in longest dimension). 
The term "pulp" is intended to refer to a mass of fibers which have been 
mechanically masticated or ground, causing the fibers to separate, split, 
fray, fibrillate and/or shred into generally finer diameter units. The 
intertangling between the units, or "interfelting," is thereby enhanced, 
thus allowing the formation of thin, yet coherent sheets. The fibers and 
fragments may, in addition, become crimped, branched, or multiply 
bifurcated to improve the interfelting. 
The grinding/masticating step required to produce the pulp may involve a 
series of techniques rater than just a single operation. The term 
"pulping" is herein used to collectively refer to the entire 
grinding/mastication operation employed in the production of pulp. The 
pulping is normally performed in a water slurry. A typical solids ratio 
during pulping is 0.05 to 5 percent by weight with the most preferred 
range being 0.5 to 2 percent by weight solids. 
The fibrils which are produced commonly exhibit a ratio of length to 
diameter which is generally greater than that exhibited by the fibers. For 
example, the length to diameter ratio exhibited by the fibers generally 
ranges from about 30:1 to about 300:1, while the corresponding ratio for 
the fibrils ranges from about 50:1 to about 600:1. The fibrils preferably 
exhibit a diameter of about 0.5 micron to about 5 microns and a length of 
about 50 microns to about 3 millimeters. 
The denier of the starting fibers typically ranges from 2 to 10 denier 
(i.e., 14 to 35 microns in diameter). However, fibers can be employed over 
a much broader size range, such as, for example, 0.5 to 100 denier (i.e., 
7 to 100 microns in diameter). A typical starting length ranges from 1/32 
to 1/4 inch. If a starting length of greater than 1/8" is employed, the 
pulping method chosen should be capable of length reduction as well as 
fibrillation to avoid the possibility of clumping of pulp particles in the 
slurry. 
Common pulping methods which may be employed include air fibrillation, or 
the use of a pulp refiner, open disk emulsifier, blender, grindstone, 
mill, Jordan or Valley pulp beater, or segmented impeller emulsifier. The 
use of surface wetting agents or 50 percent isopropanol or ethanol may 
facilitate the fibrillation of the polymer. 
While the use of fibers is preferred, it is also possible to use articles 
of other shapes and configurations. For example, the polymer may also be 
in the form of pellets or sheets, etc. The term shaped article as used 
herein is intended to include particles, pellets, filaments, staple 
fibers, films, sheets and other extruded, molded, cast or otherwise formed 
shaped articles. 
It should be noted, however, that the more highly oriented is the polymer 
in the article, the higher the aspect ratio of the fibrils which are 
formed will be. It is therefore preferable to employ articles in the 
method of the present invention which are highly oriented as a result of 
being formed (e.g., as spun fibers) so as to provide fibrils having a high 
aspect ratio. 
The fibrils which are produced can subsequently be slurried with a liquid 
which is a non-solvent for the polymer of which the fibrils are comprised 
such as water and collected (e.g., filtered) onto a web or a screen to 
provide a random (i.e., multi-dimensional) array or sheet of fibrils. In 
additon to wet laying, webs may be formed by air lay processes wherein the 
fibrous material is entrained in and deposited from a moving air stream. 
With either type of formed web, appropriate methods can then be employed 
to bond the fibrils together to form an article such as paper. For 
example, the fibrils may be thermally bonded to one another at a 
temperature below the melting temperature of the liquid crystal polymer 
comprising the fibrils by conventional means such as heat pressing or 
calendering to at least bond the fibrils together at their cross-over 
points. Heat pressing is essentially a batch process wherein the web of 
fibrils is pressed between two heated plates. Calendering involves the 
passage of the fibrils in the form of a web between heated rolls. The use 
of a padded backup roll against a heated metal roll is preferred. The 
thermal bonding temperature will generally range from about 100.degree. to 
about 250.degree. C. 
Alternatively, adhesives may be used to bond the fibrils. Suitable 
adhesives include but are not limited to the following: epoxies, 
thermosetting or thermoplastic resins such as thermosetting polyesters, 
water soluble adhesives such as casine, guar gum or polyacrylic acid, 
solvent-based adhesives and emulsion or latex based adhesives such as the 
styrene/butyl/acrylic copolymer systems. 
The temperature as well as the method of thermal bonding employed affects 
the physical characteristics exhibited by the article which is produced. 
For example, when temperatures below about 140.degree. C. are used, an 
opaque paper is provided. Such papers are essentially a mat of 
intertangled fibrous particulates (the fibrils) which exhibits substantial 
porosity and low density. On the other hand, when temperatures in excess 
of about 140.degree. C. are employed in conjunction with a pressing or 
calendering step (and especially in the range of 170.degree. C. or so), a 
transparent film or membrane resembling a glassine film is produced which 
exhibits minimal porosity. Accordingly, the use of excessively high 
temperatures and high pressure should generally be avoided if a paper of 
substantial porosity is desired since such temperatures and pressure 
increase the compaction and the degree of fusion of the fibrils to each 
other while correspondingly decreasing the porosity. 
Articles comprised of the pulp of fibrils of the present invention possess 
many advantageous properties due to the presence of thermotropic liquid 
crystal polymers therein. Since the liquid crystal polymers are highly 
oriented, the fibrils which comprise the pulp of the present invention 
possess relatively high tensile strength and high modulus. Accordingly, 
articles comprised of the pulp similarly exhibit relatively high modulus 
and high tensile strength. In addition, the articles exhibit such tensile 
strength and modulus in a multi-dimensional manner due to the 
multi-dimensional (i.e., random) orientation of the fibrils within the 
article. 
The mechanical properties of the fibrils contained in the pulp produced in 
accordance with the present invention can be improved still further by 
subjecting the fibrils to a heat treatment following formation thereof. 
The heat treatment improves the properties of the fibrils by increasing 
the molecular weight of the liquid crystalline polymer which comprises the 
fibrils 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 fibrils together during formation of a non-woven 
article. 
The fibrils 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 fibrils may be 
brought to a temperature approximately 10 to 30 centigrade degrees below 
the melting temperature of the liquid crystal polymer, at which 
temperature the fibrils remain solid. It is preferable for the temperature 
of the heat treatment to be as high as possible without equaling or 
exceeding the melting temperature of the polymer. It is most preferable to 
gradually increase the temperature of 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 from a few minutes 
to a number of days, e.g., from 0.5 to 200 hours, or more. Preferably, the 
heat treatment is conducted for a time of 1 to 48 hours and typically from 
about 5 to 30 hours. 
Generally, the 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 temperatures can be applied without melting the polymer. 
Preferably, the heat treatment is conducted under conditions 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 result 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. 
While advantages can be obtained by heat treating the fibrils prior to 
their incorporation into a non-woven article, it may be preferable to heat 
treat the fibrils subsequent to incorporation into the article since the 
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 anisotropic properties in the 
melt phase is intended to refer to the temperature below which the polymer 
exhibits such properties prior to heat treatment thereof. 
The chemical resistance of the liquid crystal polymer also increases with 
the heat treatment and the solubility into pentafluorophenol, one of the 
rare solvents for these thermotropic liquid crystal polymers, continuously 
decreases with increasing heat treatment time such that eventually the 
polymer does not dissolving even minimally (such as in amounts of 0.1 
percent by weight). 
The physical characteristics of articles produced from the pulp of the 
present invention may be varied by the addition of various additives to 
the pulp in the web formation process. For example, wetting agents, 
surface treatment agents, coloring agents and fillers can be added. Such 
additives can include reinforcing fibers of various materials including 
thermotropic liquid crystal polymeric fibers. 
The reinforcing fiber can be incorporated into the pulp over a wide range 
of proportions ranging from 0 to about 95 percent by weight or so. 
Dimensions of common reinforcing fibers range from 1 micron to 50 microns 
in diameter and from 1/32 to several inches in length, depending on the 
type of fiber and the physical characteristics desired in the final 
product. It is even possible to add continuous fiber.

The invention is additionally illustrated in connection with the following 
Examples which are to be considered as illustrative of the present 
invention. It should be understood, however, that the invention is not 
limited to the specific details of the Examples. 
EXAMPLE 1 
A polymer consisting of 30 mole percent of 6-hydroxy-2-naphthoic acid, 40 
mole percent of 4-hydroxybenzoic acid, 10 mole percent of isophthalic 
acid, 5 mole percent of terephthalic acid and 15 mole percent of 
2,6-dihydroxyanthraquinone was prepared from the following monomers: 
______________________________________ 
6-acetoxy-2-naphthoic acid 
69.1 grams 
4-acetoxy benzoic acid 72.1 grams 
isophthalic acid 16.61 grams 
terephthalic acid 8.31 grams 
2,6-diacetoxy-anthraquinone 
48.6 grams 
______________________________________ 
A one liter 3-necked flask (equipped with a glass paddle stirrer, nitrogen 
inlet and distillation head) was charged with the above monomers and 
evacuated and flushed with nitrogen three times. The flask was warmed via 
a sand bath to 250.degree.. to initiate polymerization. The polymerization 
was conducted in a nitrogen atmosphere by programming the temperature to 
increase to 310.degree. C. over a five hour period. Polymerization was 
continued under vacuum (0.7 torr) for an additional one-half hour, then 
allowed to cool to room temperature under nitrogen. The flask was broken 
to recover the polymer in the form of a solidified mass. The mass was 
broken up into small pieces by sawing. The pieces were then ground in a 
Wiley mill to a fluffy fibrillar material. 
The polymer had an inherent viscosity of 1.47 when measured at a 0.1% w/N 
solution in pentafluorophenol. When examined by differential scanning 
colorimetry (scan rate of 20.degree. C./minute), the glass transition 
temperature was found to be 120.degree. C. 
EXAMPLE 2 
The following demonstrates the advantageous fibrillation properties of the 
polymers of the present invention. Fibers comprised of 
polyparaphenyleneterephthalate (Polymer A), a polymer consisting of 40 
mole percent of 6-hydroxy-2-naphthoic acid and 60 mole percent of 
p-hydroxy benzoic acid (Polymer B) and a polymer of the present invention 
described in Example 1 (Polymer C) were masticated by use of an Ultrasonic 
Inc. sonicator, model W-375 with a Standard Microtip. Polymer B was 
masticated by pulsing the sonicator on a 50% cycle, while the remaining 
two were masticated at a continuous mode. The power output was the same 
for all runs. 
The various pulps were masticated until fully fibrillated as evidenced by 
reduction of all particulates to fibrils. The Polymer A pulp took at least 
60 minutes to fully fibrillate, the Polymer B pulp took at least 60 
minutes to fully fibrillate, and the Polymer C pulp took less than 20 
minutes to fibrillate to the same extent as the other two. 
The principles, 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.