U.S. patent application number 16/868158 was filed with the patent office on 2020-08-27 for liquid crystalline polyester compositions and methods.
The applicant listed for this patent is ExxonMobil Chemical Patents Inc., Virginia Tech Intellectual Properties, Inc.. Invention is credited to Ting Chen, Javier Guzman, Katherine V. Heifferon, Timothy E. Long, Syamal Tallury, S. Richard Turner, Yong Yang.
Application Number | 20200270396 16/868158 |
Document ID | / |
Family ID | 1000004867469 |
Filed Date | 2020-08-27 |
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United States Patent
Application |
20200270396 |
Kind Code |
A1 |
Heifferon; Katherine V. ; et
al. |
August 27, 2020 |
LIQUID CRYSTALLINE POLYESTER COMPOSITIONS AND METHODS
Abstract
Liquid crystalline hydroquinone-3,4'-biphenyl dicarboxylate
polyesters, and methods of making them. The polyesters may be melt
processed at a temperature below the thermal decomposition
temperature and the isotropic temperature, and may form a liquid
crystalline glass phase. The polyesters may be formed by
polycondensation of hydroquinone or a hydroquinone derivative with
3,4'-biphenyl dicarboxylic acid.
Inventors: |
Heifferon; Katherine V.;
(Bear, DE) ; Long; Timothy E.; (Blacksburg,
VA) ; Turner; S. Richard; (Blacksburg, VA) ;
Yang; Yong; (Kingwood, TX) ; Tallury; Syamal;
(Katy, TX) ; Chen; Ting; (Friendswood, TX)
; Guzman; Javier; (Porter, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Chemical Patents Inc.
Virginia Tech Intellectual Properties, Inc. |
Baytown
Blacksburg |
TX
VA |
US
US |
|
|
Family ID: |
1000004867469 |
Appl. No.: |
16/868158 |
Filed: |
May 6, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2018/049462 |
Sep 5, 2018 |
|
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16868158 |
|
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62586283 |
Nov 15, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 63/06 20130101;
C08G 63/185 20130101; C08G 63/191 20130101; C08G 2250/00 20130101;
C09K 19/38 20130101; C08G 63/80 20130101 |
International
Class: |
C08G 63/191 20060101
C08G063/191; C08G 63/185 20060101 C08G063/185; C08G 63/06 20060101
C08G063/06; C08G 63/80 20060101 C08G063/80 |
Claims
1. A liquid crystalline polyester comprising: a dihydroxy component
comprising at least about 80 mole percent of hydroquinone, based on
the total moles of the dihydroxy component; and a diacid component
comprising at least about 80 mole percent of 3,4'-biphenyl
dicarboxylate, based on the total moles of the diacid component;
wherein the polyester has a flow temperature (T.sub.f) as
determined by ASTM D4065 at 1 Hz below an isotropic temperature
(T.sub.i) determined by DSC with a heat/cool/heat cycle (second
heating) at a heating rate of 10.degree. C./min and cooling rate of
100.degree. C./min.
2. The polyester of claim 1, further comprising a
hydroxy-carboxylic acid component in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-carboxylic acid component.
3. The polyester of claim 1, consisting essentially of hydroquinone
and 3,4'-biphenyl dicarboxylate.
4. The polyester of claim 1, wherein the dihydroxy component
consists of hydroquinone, and the diacid component consists of
3,4'-biphenyl dicarboxylate.
5. The polyester of claim 4, wherein the polyester is free of a
hydroxy-carboxylic acid component.
6. The polyester of claim 1, further comprising one or more
comonomers in an amount effective to modify: crystallinity as
determined by ASTM D3418; heat of fusion (.DELTA.H.sub.f) as
determined by ASTM D341; glass transition temperature (T.sub.g), as
determined by ASTM D3418; thermal decomposition temperature
(T.sub.d,5%) as determined by ASTM D3850 using a temperature ramp
of 10.degree. C./min under nitrogen; the T.sub.f; the T.sub.i; zero
shear melt viscosity (.eta.*) determined at 340.degree. C. at a
frequency of 0.1 radians/second, by frequency sweep on 8 mm
parallel plates under nitrogen at 1% strain; or a combination
thereof.
7. The polyester of claim 6, further comprising one or more of the
following: wherein the dihydroxy component comprises one or more
aromatic dihydroxy component comonomers in an amount up to 20 mole
percent, based on the total moles of the dihydroxy component;
wherein the diacid component comprises one or more aromatic diacid
component comonomers in an amount up to 20 mole percent, based on
the total moles of the diacid component; wherein the polyester
comprises a hydroxy-carboxylic acid comonomer in an amount up to 20
mole percent, based on the total moles of the diacid component and
the hydroxy-acid comonomer.
8. The polyester of claim 7, further comprising one or more of the
following: wherein the one or more aromatic dihydroxy comonomers is
selected from: resorcinol, 4,4-dihydroxybiphenyl, and combinations
thereof; wherein the one or more aromatic diacid comonomers is
selected from: terephthalic acid (TA), naphthalene dicarboxylic
acid (NDA), 4,4'-biphenyl dicarboxylate (4,4'BB), isophthalic acid
(IA), and combinations thereof; wherein the hydroxy-carboxylic acid
comonomer is p-hydroxy benzoic acid.
9. The polyester of claim 1, wherein the T.sub.i is less than the
thermal decomposition temperature (T.sub.d,5%) as determined by
ASTM D3850 using a temperature ramp of 10.degree. C./min under
nitrogen.
10. The polyester of claim 1, wherein the polyester exhibits one or
more of the following: a thermal decomposition temperature
(T.sub.d,5%) as determined by ASTM D3850 using a temperature ramp
of 10.degree. C./min under nitrogen, of about 400.degree. C. or
more; the T.sub.f is about 350.degree. C. or less; the T.sub.i is
about 350.degree. C. or less; a glass transition temperature
(T.sub.g) as determined by ASTM D3418, of about 220.degree. C. or
less; a zero-shear melt viscosity (.eta.*) determined at
340.degree. C. at a frequency of 0.1 radians/second, by frequency
sweep on 8 mm parallel plates under nitrogen at 1% strain, of at
least about 50,000 Pa-s.
11. A method comprising: contacting a dihydroxy component
comprising at least about 80 mole percent of hydroquinone or a
hydroquinone diester derivative, based on the total moles of the
dihydroxy component, with a diacid component comprising at least
about 80 mole percent of 3,4'-biphenyl dicarboxylic acid (3,4'-BB)
or an ester derivative of 3,4'-BB, based on the total moles of the
diacid component, under polycondensation conditions; forming a
polyester comprising the dihydroxy and diacid components; and
processing the polyester in a liquid crystalline glass phase.
12. The method of claim 11, wherein the contacting is in the
presence of a hydroxy-carboxylic acid component in an amount up to
20 mole percent, based on the total moles of the diacid component
and the hydroxy-carboxylic acid component
13. The method of claim 11, wherein the polyester consists
essentially of hydroquinone and 3,4'-biphenyl dicarboxylate.
14. The method of claim 11, wherein the dihydroxy component
consists of hydroquinone, and the diacid component consists of
3,4'-biphenyl dicarboxylate.
15. The method of claim 14, wherein the polyester is free of a
hydroxy-carboxylic acid component.
16. The method of claim 11, wherein the dihydroxy component
comprises the hydroquinone diester derivative comprising the
reaction product of a hydroquinone with a carboxylic acid
comprising from 1 to 6 carbon atoms or an anhydride comprising from
2 to 14 carbon atoms, to form the hydroquinone diester
derivative.
17. The method of claim 16, wherein the hydroquinone diester
derivative is hydroquinone dipivalate.
18. The method of claim 11, wherein the diacid component comprises
3,4'-BB in the free acid form.
19. The method of claim 11, wherein the polyester further comprises
one or more comonomers in an amount effective to modify:
crystallinity as determined by ASTM D3418; heat of fusion
(.DELTA.H.sub.f) as determined by ASTM D341; glass transition
temperature (T.sub.g), as determined by ASTM D3418; thermal
decomposition temperature (T.sub.d,5%) as determined by ASTM D3850
using a temperature ramp of 10.degree. C./min under nitrogen; the
T.sub.f; the T.sub.i; zero shear melt viscosity (.eta.*) determined
at 340.degree. C. at a frequency of 0.1 radians/second, by
frequency sweep on 8 mm parallel plates under nitrogen at 1%
strain; or a combination thereof.
20. The method of claim 19, further comprising one or more of:
wherein the dihydroxy component comprises one or more aromatic
dihydroxy component comonomers in an amount up to 20 mole percent,
based on the total moles of the dihydroxy component; wherein the
diacid component comprises one or more aromatic diacid component
comonomers in an amount up to 20 mole percent, based on the total
moles of the diacid component; wherein the polyester comprises a
hydroxy-carboxylic acid comonomer in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-acid comonomer.
21. The method of claim 20, further comprising one or more of the
following: wherein the one or more aromatic dihydroxy comonomers is
selected from: resorcinol, 4,4-dihydroxybiphenyl, and combinations
thereof; wherein the one or more aromatic diacid comonomers is
selected from: terephthalic acid (TA), naphthalene dicarboxylic
acid (NDA), 4,4'-biphenyl dicarboxylate (4,4'BB), isophthalic acid
(IA), and combinations thereof; wherein the hydroxy-carboxylic acid
comonomer is p-hydroxy benzoic acid.
22. The method of claim 11, wherein the polyester formation is by
acidolysis polycondensation.
23. The method of claim 22, further comprising hydrolyzing a
3,4'-bibenzoate diester to form the 3,4'-BB free acid.
24. The method of claim 22, further comprising esterifying
hydroquinone with an ester-forming carboxylic acid, carboxylic acid
anhydride, or combination thereof.
25. The method claim 24, wherein the carboxylic acid or anhydride
is selected from acetic acid, acetic anhydride, pivalic acid,
pivalic anhydride, or a combination thereof.
26. The method of claim 11, further comprising forming the
polyester into a shaped article.
27. The method of claim 26, wherein the shaped article comprises a
fiber, a nonwoven fabric, a film, or a molded article.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation in part of PCT
US2018/049462, filed 5 Sep. 2018, which claims the benefit of and
priority to provisional application U.S. 62/586,283, filed 15 Nov.
2017.
THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
[0002] ExxonMobil Chemical Company, a division of ExxonMobil
Corporation, and Virginia Polytechnic Institute and State
University.
BACKGROUND OF THE INVENTION
[0003] There is a need in the art for new liquid crystalline
polymers. Such polymers must have a working temperature for melt
processing before the onset of degradation. Desirably, such
polymers would also have good thermomechanical properties, high
flame resistance, and good processability.
[0004] Liquid crystalline polyesters generally require linear
aromatic monomers, e.g., 1,4-aromatic carbocyclic ring systems or
4,4'-biphenylenes, and/or comonomers to reduce the glass and
isotropic transition temperatures below the degradation temperature
of the polymer, and thus their syntheses can be complicated. For
example, U.S. Pat. No. 4,118,372 discloses an anisotropic
(co)polyester made from chlorohydroquinone diacetate, terephthalic
acid, and 4,4'-bibenzoic acid.
[0005] Aromatic polyesters where the aromatic diacid component is
isophthalic acid, terephthalic acid, or naphthalene dicarboxylic
acid, have only produced semi-crystalline polymers or polymers with
transition temperatures above the polymer degradation temperature,
e.g., poly(p-phenylene terephthalate) and poly(p-hydroxybenzoic
acid) melt above 600.degree. C. These polymers typically require
three, four or more comonomers to achieve heat resistance and a
melting temperature range suitable for processing. For example,
U.S. Pat. Nos. 5,110,896, 5,250,654, 5,397,502, and 6,656,386
disclose liquid crystalline polymers made from several comonomers
derived from hydroquinone, 4,4'-dihydroxybiphenyl, terephthalic
acid, 2,6-naphthalenedicarboxylic acid, 4,4'-bibenzoic acid,
4-hydroxybenzoic acid, isophthalic acid, 3,4'-bibenzoic acid,
etc.
[0006] There is thus a need for new aromatic liquid crystalline
polyesters that do not necessarily require the presence of
comonomers, and/or that have a reduced or no comonomer content, to
achieve heat resistance and/or a melting temperature range that may
facilitate a commercial manufacturing process, and/or for a
simplified method to make and/or process liquid crystalline
polyesters.
SUMMARY OF THE INVENTION
[0007] This summary is provided to introduce a selection of
concepts that are further described below in the detailed
description. This summary is not intended to find key or essential
features of the claimed subject matter, nor is it intended to be
used as an aid in limiting the scope of the claimed subject
matter.
[0008] We have discovered a melt processable liquid crystalline
polyester that may consist of or consist essentially of
hydroquinone as the dihydroxy component and 3,4'-biphenyl
dicarboxylate as the diacid component.
[0009] In one aspect, the present disclosure provides a liquid
crystalline polyester comprising: a dihydroxy component comprising
at least about 80 mole percent of hydroquinone, based on the total
moles of the dihydroxy component; a diacid component comprising at
least about 80 mole percent of 3,4'-biphenyl dicarboxylate, based
on the total moles of the diacid component. The polyester
preferably has a flow temperature (T.sub.f) as determined by ASTM
D4065 at 1 Hz below an isotropic temperature (T.sub.i) determined
by DSC with a heat/cool/heat cycle (second heating) at a heating
rate of 10.degree. C./min and cooling rate of 100.degree. C./min.
The polyester may further comprise an optional hydroxy-carboxylic
acid component in an amount up to 20 mole percent, based on the
total moles of the diacid component and the hydroxy-carboxylic acid
component.
[0010] In another aspect, the present disclosure provides a method
comprising contacting a dihydroxy component comprising at least
about 80 mole percent of hydroquinone or a hydroquinone derivative,
with a diacid component comprising at least about 80 mole percent
of 3,4'-biphenyl dicarboxylic acid (3,4'-BB), based on the total
moles of the diacid component, under polycondensation conditions;
forming a polyester comprising the dihydroxy component and the
diacid components; and processing the polyester in a liquid
crystalline glass phase.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is a .sup.1H NMR spectrum and peak assignment for
the hydrolyzed 3,4'-bibenzoate according to Example 1 below.
[0012] FIG. 1B is a .sup.13C NMR spectrum and peak assignment for
the hydrolyzed 3,4'-bibenzoate according to Example 1 below.
[0013] FIG. 2A is a line drawing reproduction of a photograph of
the poly(hydroquinone-3,4'-bibenzoate) obtained from the reactor
according to Example 2 below.
[0014] FIG. 2B is a line drawing reproduction of a photograph
indicating the darker color of the
poly(hydroquinone-3,4'-bibenzoate) obtained from the reactor
according to Example 3 below.
[0015] FIG. 2C is a line drawing reproduction of a photograph of a
compression molded disk of the poly(hydroquinone-3,4'-bibenzoate)
of Example 2, partially overlapping a compression molded disk of
the poly(hydroquinone-3,4'-bibenzoate) of Example 3, which uses
gradient stippling to indicate the transparency or opacity of the
examples observed in the photograph.
[0016] FIG. 3A is a line drawing reproduction of a polarized
optical microscopic photograph of
poly(hydroquinone-3,4'-bibenzoate) at 150.degree. C. according to
Examples 2 and 3 below, in which gradient stippling and dashed
lines are used to indicate the birefringence observed in the
photograph of the example.
[0017] FIG. 3B is a line drawing reproduction of a polarized
optical microscopic photograph of
poly(hydroquinone-3,4'-bibenzoate) at 290.degree. C. according to
Examples 2 and 3 below, in which gradient stippling and dashed
lines are used to indicate the observed birefringence in the
photograph of the example.
[0018] FIG. 3C is a line drawing reproduction of a polarized
optical microscopic photograph of
poly(hydroquinone-3,4'-bibenzoate) at 348.degree. C. according to
Examples 2 and 3 below, in which gradient stippling and dashed
lines are used to indicate the observed loss in birefringence
observed in the photograph of the example.
[0019] FIG. 4 shows the second heating curves from differential
scanning calorimetry (DSC) of the
poly(hydroquinone-3,4'-bibenzoates) according to Examples 2 and 3
below.
[0020] FIG. 5 shows the frequency sweep curves for the
poly(hydroquinone-3,4'-bibenzoates) according to Examples 2 and 3
below.
[0021] FIG. 5A shows the power law fits of the frequency sweep
curves for the poly(hydroquinone-3,4'-bibenzoates) of FIG. 5.
[0022] FIG. 6 shows the dynamic mechanical analysis (DMA) curves
for the poly(hydroquinone-3,4'-bibenzoate) according to Example 2
below.
[0023] FIG. 7 shows the second heating curves from DSC of the
poly(hydroquinone-3,4'-bibenzoate-co-isophthalate) series according
to Examples 4-6 below.
[0024] FIG. 8 shows the DMA curves for the
poly(hydroquinone-3,4'-bibenzoate-co-isophthalate) series according
to Examples 4-6 below.
[0025] FIG. 9 is a chart of line drawing reproductions of the
polarized optical microscopic photographs for the
poly(hydroquinone-3,4'-bibenzoate-co-isophthalate) series by
comonomer content versus temperature according to Examples 4-6
below, in which gradient stippling and dashed lines are used to
indicate the observed birefringence or loss in birefringence
observed in the photograph of the example.
[0026] FIG. 10 shows the frequency sweep curves for the
poly(hydroquinone-3,4'-bibenzoate-co-isophthalate) series by
comonomer content versus temperature according to Examples 4-6
below.
[0027] FIG. 11 shows the second heating curves from DSC of the
poly(hydroquinone-3,4'-bibenzoate-co-terephthalate) series
according to Examples 7-9 below.
[0028] FIG. 12 is a chart of line drawing reproductions of the
polarized optical microscopic photographs for the
poly(hydroquinone-3,4'-bibenzoate-co-terephthalate) series by
comonomer content versus temperature according to Examples 7-9
below, in which gradient stippling and dashed lines are used to
indicate the observed birefringence or loss in birefringence
observed in the photograph of the example.
[0029] FIG. 13 shows the DMA curves for the
poly(hydroquinone-3,4'-bibenzoate-co-terephthalate) series
according to Examples 7-9 below.
[0030] FIG. 14 shows the frequency sweep curves for the
poly(hydroquinone-3,4'-bibenzoate-co-terephthalate) series by
comonomer content versus temperature according to Examples 7-9
below.
[0031] FIG. 15 shows the second heating curves from DSC of the
poly(hydroquinone-3,4'-bibenzoate-co-naphthalene dicarboxylate)
series according to Examples 7-9 below.
[0032] FIG. 16 is a chart of line drawing reproductions of the
polarized optical microscopic photographs for the
poly(hydroquinone-3,4'-bibenzoate-co-naphthalene dicarboxylate)
series by comonomer content versus temperature according to
Examples 10-13 below, in which gradient stippling and dashed lines
are used to indicate the observed birefringence or loss in
birefringence observed in the photograph of the example.
[0033] FIG. 17 shows the DMA curves for the
poly(hydroquinone-3,4'-bibenzoate-co-naphthalene dicarboxylate)
series according to Examples 10-13 below.
[0034] FIG. 18 shows the frequency sweep curves for the
poly(hydroquinone-3,4'-bibenzoate-co-naphthalene dicarboxylate)
series by comonomer content versus temperature according to
Examples 10-13 below.
[0035] FIG. 19 shows the second heating curve from DSC of the
poly(hydroquinone-3,4'-bibenzoate-co-4,4'-bibenzoate) according to
Example 14 below.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Throughout the entire specification, including the claims,
the following terms shall have the indicated meanings.
[0037] The term "and/or" refers to both the inclusive "and" case
and the exclusive "or" case, and such term is used herein for
brevity. For example, a composition comprising "A and/or B" may
comprise A alone, B alone, or both A and B.
[0038] The term "consisting essentially of" in reference to a
composition is understood to mean that the composition can include
additional compounds other than those specified, in such amounts to
the extent that they do not substantially interfere with the
essential function of the composition, or if no essential function
is indicated, in any amount up to 5 percent by weight of the
composition or component, preferably an amount up to 2 percent by
weight of the composition or component, more preferably an amount
up to 1 percent by weight of the composition or component.
[0039] For purposes herein, a "polymer" refers to a compound having
two or more "mer" units, that is, a degree of polymerization of two
or more, where the mer units can be of the same or different
species. The term "polyester," as used herein, refers to a polymer
comprised of residues derived from one or more polyfunctional acid
moieties, collectively referred to herein as the "diacid
component," in ester linkage with residues derived from one or more
polyhydroxyl compounds, which may also be referred to herein as
"polyols" and collectively as the "dihydroxy component." The term
"repeating unit," also referred to as the "mer" units, as used
herein with reference to polyesters refers to an organic structure
having a diacid component residue and a dihydroxy component residue
bonded through a carbonyloxy group, i.e., an ester linkage. Mole
percentages of the diacid and dihydroxy components are expressed
herein based on the total moles of the respective component, i.e.,
the polyesters comprise 100 mole percent of the polyfunctional acid
component and 100 mole percent of the polyfunctional hydroxyl
component.
[0040] As used herein, a "homopolymer" is a polymer having mer
units or residues that are the same species, e.g., a homopolyester
has ester residues derived from a single diacid and a single
dihydroxy. A "copolymer" is a polymer having two or more different
species of mer units or residues, e.g., a (co)polyester has more
than one species of ester residues derived from more than one
diacid and/or more than one dihydroxy. Unless otherwise indicated,
reference to a polymer herein includes a copolymer, a terpolymer,
or any polymer comprising a plurality of the same or different
species of repeating units.
[0041] The term "residue," as used herein, means the organic
structure of the monomer in its as-polymerized form as incorporated
into a polymer, e.g., through a polycondensation and/or an
esterification or transesterification reaction from the
corresponding monomer. Throughout the specification and claims,
reference to the monomer(s) in the polymer is understood to mean
the corresponding as-polymerized form or residue of the respective
monomer. For purposes herein, it is to be understood that by
reference to a polyester comprising a diacid component and a
dihydroxy component, the diacid and dihydroxy components are
present in the polymer in the as-polymerized (as-condensed) form.
For example, the diacid component is present in the polymer as
dicarboxylate in alternating ester linkage with the dihydroxy
component, yet the polyester may be described as being comprised of
the dicarboxylic acid (or derivative) and the dihydroxy derivative,
e.g., hydroquinone diacetate-3,4'-bibenzoate polyester
("poly(HQa-3,4'BB)") or hydroquinone dipivilate-3,4'-bibenzoate
polyester ("poly(HQp-3,4'BB)"), where it is understood the acetyl
or pivalyl ester groups in the starting material(s) are not
generally present in the polyester, but may be present in minor or
trivial amounts, e.g., as esters on the ends of some of the polymer
chains.
[0042] The aforementioned dicarboxylic acid residues, e.g.,
3,4'-biphenyl dicarboxylic acid residues, i.e., the dicarboxylate
mer units, may be derived from a polyfunctional acid monomer or an
ester producing equivalent thereof. Examples of ester producing
equivalents of polyfunctional acids include one or more
corresponding acid halide(s), ester(s), salts, the anhydride, or
mixtures thereof. As used herein, therefore, the term "diacid" is
intended to include polycarboxylic acids and any derivative of a
polycarboxylic acid, including its associated acid halides, esters,
half-esters, salts, half-salts, anhydrides, mixed anhydrides, or
mixtures thereof, capable of forming esters useful in a reaction
process with a dihydroxy to make polyesters.
[0043] As used herein, the term "birefringence" refers to the
optical property of a material having a refractive index that
depends on the polarization and propagation direction of light.
Such materials are optically anisotropic and are said to be
birefringent, or birefractive.
[0044] As used herein, the term "liquid crystal" (LC) refers to a
state of matter having properties intermediate those of
conventional liquids and solid crystals, in which the liquid
crystal may flow like a liquid, but its molecules may be oriented
in a crystal-like way that may be observed as birefringence.
[0045] As used herein, a "nematic mesophase" refers to a state of a
liquid crystal in which rod-shaped molecules have no positional
order, but are self-aligned to have their long axes oriented
substantially parallel but not arranged in well-defined planes. As
used herein "smectic mesophase" refers to a liquid crystal in which
rod-shaped molecules are positionally ordered along one direction
in well-defined layers, oriented either along the layer or tilted
away from the layer.
[0046] As used herein, a "liquid crystalline polymer" is a polymer
that is anisotropic and/or birefringent when viewed using polarized
optical microscopy as described in U.S. Pat. No. 4,118,372, which
is hereby incorporated herein by reference. The terms "liquid" and
"crystalline" in "liquid crystalline polymer" refer to the LC type
of crystalline-like ordering that is normally seen in liquid
crystals, and do not necessarily connote that the polymer is in the
liquid phase or has classic crystallinity, e.g., the polymer may
exhibit anisotropy as either or both of liquid and solid phases,
and the solid polymer may have any of crystalline, semicrystalline,
liquid crystal, and amorphous morphologies.
[0047] As used herein, a "liquid crystalline glass" refers to a
polymer that maintains liquid crystalline ordering, but does not
generally form crystalline domains.
[0048] As used herein, the flow temperature (T.sub.flow) is the
temperature below which the fluid will not flow, and is determined
experimentally as the onset point of the second storage modulus
drop during a dynamic mechanical analysis (DMA) scan on a
compression molded film with a thickness of 400 .mu.m at a
frequency of 1 Hz and a temperature increase ramp of 3.degree.
C./min. For purposes herein the flow temperature is determined
according to ASTM D4065 at 1 Hz unless otherwise indicated.
[0049] As used herein, the thermal decomposition temperature
(T.sub.d,5%) refers to the temperature in a thermogravimetric
analysis at which 5 wt % of the sample is lost, and is determined
according to ASTM D3850 by using a temperature ramp of 10.degree.
C./min under nitrogen.
[0050] As used herein, the heat of fusion .DELTA.H.sub.f (i.e., the
specific heat at constant pressure-.DELTA.Cp), and the
crystallinity of a polymer are determined using differential
scanning calorimetry (DSC) according to standard laboratory
practices. Isotropic temperature (T.sub.i) and the heat of melting
(.DELTA.Hi) refers to the temperature at which a material
transitions between isotropic and anisotropic, and is determined
via DSC by using a heat/cool/heat cycle (second heating) at a
heating rate of 10.degree. C./min and cooling rate of 100.degree.
C./min to obtain glass transition temperature (T.sub.g) and
isotropic temperature (T.sub.i), which are determined consistent
with ASTM D3418, unless otherwise indicated.
[0051] As used herein, the zero-shear melt viscosity (.eta.*)
refers to the apparent viscosity at the indicated temperature,
which for purposes herein is 340.degree. C. unless otherwise
indicated, and a frequency of 0.1 radians/second, and is determined
by a frequency sweep study on 8 mm parallel plates under nitrogen
at 1% and/or 1.25% strain. In case of a conflict, the zero-shear
melt viscosity determined at 1% strain is used.
[0052] For purposes herein, the terms flexural modulus, flexural
strength, tensile modulus, tensile strength, at maximum load and
tensile strain to failure are used consistent with their well
understood meaning in the art and are determined consistent with
ASTM D638 unless otherwise specified.
[0053] Unless indicated otherwise, for purposes herein an
essentially amorphous polymer is defined as a polymer that does not
exhibit a substantially crystalline melting point, Tm, i.e., no
discernable heat of fusion or a heat of fusion less than 5 J/g,
when determined by a heat/cool/reheat differential scanning
calorimetry (DSC) analysis from the second heating ramp by heating
of the sample from 0.degree. C. to 360.degree. C. at a heating and
cooling rate of 10.degree. C./min. The sample is held for 3 min
between heating and cooling scans. For purposes herein, an
amorphous polymer may alternatively be indicated if injection
molding of the polymer produces an article which is essentially
clear, wherein the injection molding process used is known to
produce articles having cloudy or opaque character upon injection
molding of a semi-crystalline polymer having similar properties to
the amorphous polymer.
[0054] For purposes herein, the melting temperature,
crystallization temperature, glass transition temperature, etc.,
are determined by a heat/cool/reheat DSC analysis from the second
heating ramp by heating of the sample from 0.degree. C. to
360.degree. C. at a heating and cooling rate of 100.degree. C./min.
The sample is held for 3 min between heating and cooling scans.
Unless otherwise indicated, the heat of fusion, the amount of
crystallization, and glass transition temperatures are determined
at the midpoint of the respective endotherm or exotherm in the
second heating ramp.
[0055] As used herein, "polycondensation" refers to the formation
of a polymer by the linking together of molecules of one or more
monomers with the subsequent releasing of water, or a similarly
small molecule. As used herein, "acidolysis polycondensation"
refers to a unique form of polycondensation in which a
polycarboxylic acid in the free acid form is reacted with a
poly-hydroxy compound or a derivative thereof, to form the
resultant polyester linkages with the subsequent release of water
or other leaving group. Acidolysis polycondensation also includes
the reaction of a polycarboxylic acid in the free acid form with a
polyhydroxy compound comprising a plurality of esterified phenolic
substituents, e.g., hydroquinone dialkanoate (e.g., hydroquinone
diacetate) with the subsequent formation of the phenol
esterification acid; the esterified polyphenol is utilized as the
polyhydroxy compound.
[0056] For purposes herein, a "dihydroxy compound" refers to a
compound comprising a plurality of hydroxyl groups or functional
groups derived from hydroxyl groups, e.g., esters, ethers, and the
like. The term dihydroxy compound is not limited to poly alcohols,
diols and derivatives thereof, but further includes polyphenolic
compounds and esters thereof, e.g., hydroquinone and hydroquinone
diacetate, respectively.
[0057] As used herein, "purifying" refers to removing contaminants.
As used herein, "recrystallization" refers to the purification of a
material by dissolution of the material in a solvent and
precipitating the material from the solution, where the
precipitated material has a higher purity than the starting
material.
[0058] The following abbreviations and symbols are used herein:
ASTM is ASTM International, formerly the American Society for
Testing and Materials; 3,4'BB is 3,4'-biphenyl dicarboxylic acid;
4,4'BB is 4,4'-biphenyl dicarboxylic acid; CDCl.sub.3 is deuterated
chloroform; DCA is dichloroacetic acid; DMA is dynamic mechanical
analysis; DMSO-d6 is deuterated dimethyl sulfoxide; DSC is
differential scanning calorimetry; .eta.* is zero shear melt
viscosity; HDT is heat distortion temperature; HQ is hydroquinone;
HQ.sub.a is hydroquinone diacetate; HQ.sub.p is hydroquinone
dipivalate; IA is isophthalic acid; NDA is naphthalene dicarboxylic
acid; POM is polarized optical microscopy; TA is terephthalic acid;
T.sub.d,5% is thermal decomposition temperature; TFA is
trifluoroacetic acid; TFA-d is deuterated trifluoroacetic acid; the
letter "d" prior to a chemical name also indicates a deuterated
compound; T.sub.f is flow temperature; T.sub.g is glass transition
temperature; TGA is thermogravimetric analysis; THF is
tetrahydrofuran; T.sub.i is isotropic temperature; and T.sub.m is
melting temperature.
[0059] Polyesters according to any embodiment herein may be
prepared from reaction of a diacid component comprising at least
about 80 mole percent of 3,4'BB or a derivative thereof, and a
dihydroxy component comprising at least about 80 mole percent of
hydroquinone or an ester-forming equivalent thereof, based on the
total moles of the diacid component, under polycondensation
conditions, which are incorporated into the polyester as their
corresponding residues (i.e., in polymerized form). The polyesters
useful in the present invention can contain an excess of the diacid
component or an excess of the dihydroxy component to form
corresponding diacid or dihydroxy oligomeric units, but preferably
contain substantially equal molar proportions of diacid residues
and dihydroxy residues such that the total moles of
diacid/dihydroxy repeating units, of a diacid in which one of the
two acid groups is esterified with one of the two hydroxyl groups
of the dihydroxy, are equal to 100 mole percent.
[0060] In any embodiment of the invention, the liquid crystalline
polyester may comprise at least about 80 mole percent of a
dihydroxy component comprising hydroquinone; and a diacid component
comprising at least about 80 mole percent of 3,4'-biphenyl
dicarboxylate. The polyester can have a flow temperature (T.sub.f)
as determined by ASTM D4065 at 1 Hz below an isotropic temperature
(T.sub.i) determined by DSC with a heat/cool/heat cycle (second
heating) at a heating rate of 10.degree. C./min and cooling rate of
100.degree. C./min. In any embodiment, the polyester may further
exhibit birefringence and/or anisotropy, and may preferably
comprise a liquid crystalline polyester comprising
poly(hydroquinone-3,4'-bibenzoate). In any embodiment, the
polyester may further comprise a nematic mesophase or a smectic
mesophase.
[0061] In any embodiment, the polyester may further comprise a
hydroxy-carboxylic acid component in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-carboxylic acid component.
[0062] In any embodiment of the invention, the polyester may
preferably consist essentially of, or consist of, hydroquinone and
3,4'-biphenyl dicarboxylate, e.g., the dihydroxy component can
consist of hydroxyquinone and the diacid component can consist of
3,4-biphenyl dicarboxylate. In any embodiment, the polyester can be
free of or essentially free of the hydroxy-carboxylic acid
component.
[0063] In any embodiment of the invention, the dihydroxy component,
the diacid component, or both the dihydroxy and diacid components,
may further comprise one or more comonomers in an amount effective
to: modify crystallinity, preferably increase crystallinity; modify
heat of fusion (.DELTA.H.sub.f), preferably increase heat of
fusion; modify glass transition temperature (T.sub.g), preferably
increase T.sub.g; modify thermal decomposition temperature
(T.sub.d,5%), preferably increase T.sub.d,5%; modify flow
temperature (T.sub.f), preferably decrease T.sub.f; modify
isotropic temperature (T.sub.i), preferably increase T.sub.i;
modify zero shear melt viscosity (.eta.') at 340.degree. C.,
preferably decrease .eta.*; or modify a combination thereof.
Preferably, the one or more comonomers are aromatic.
[0064] In any embodiment of the invention: (a) the dihydroxy
component may comprise one or more dihydroxy component comonomers,
preferably in an amount up to 20 mole percent, preferably from 0.1
to 20 mole percent, more preferably from 0.1 to 10 mole percent, of
the total moles of the dihydroxy component; (b) the diacid
component may comprise one or more diacid component comonomers in
an amount up to 20 mole percent, preferably from 0.1 to 20 mole
percent, more preferably from 0.1 to 10 mole percent, of the total
moles of the diacid component, based on the total moles of the
diacid component; (c) the polyester may comprise a
hydroxy-carboxylic acid comonomer in an amount up to 20 mole
percent, preferably from 0.1 to 20 mole percent, more preferably
from 0.1 to 10 mole percent, of the total moles of the diacid
component and the hydroxy-carboxylic acid comonomer; or (d) any
combination thereof. Preferably, the one or more comonomers are
aromatic.
[0065] In any embodiment of the invention: (a) the dihydroxy
component may further comprise up to 20 mole percent, preferably
from 0.1 to 20 mole percent, more preferably from 0.1 to 10 mole
percent, of the total moles of the dihydroxy component, of a
dihydroxy comonomer, preferably an aromatic dihydroxy comonomer,
preferably selected from: resorcinol, 4,4-dihydroxybiphenyl, and
combinations thereof, preferably wherein hydroquinone comprises at
least 80 mole percent of the dihydroxy component based on the total
moles of the dihydroxy component; and/or (b) the diacid component
may further comprise up to 20 mole percent, preferably from 0.1 to
20 mole percent, more preferably from 0.1 to 10 mole percent, of
the total moles of the diacid component, of a diacid comonomer,
preferably an aromatic diacid comonomer, preferably selected from:
terephthalic acid (TA), naphthalene dicarboxylic acid (NDA),
4,4'-biphenyl dicarboxylate (4,4'BB), hydroxybenzoic acid (HBA),
isophthalic acid (IA), and combinations thereof, preferably wherein
3,4'-biphenyl dicarboxylate comprises at least 80 mole percent of
the diacid component, based on the total moles of the diacid
component.
[0066] In any embodiment of the invention: (a) the diacid component
may further comprise up to 20 mole percent, preferably from 0.1 to
20 mole percent, preferably from 0.1 to 10 mole percent, of the
total moles of the diacid component of one or more diacid
comonomers to modify T.sub.g, preferably to increase T.sub.g,
preferably wherein the one or more diacid comonomers comprises
isophthalic acid (IA), preferably wherein 3,4'-biphenyl
dicarboxylate comprises at least 80 mole percent of the diacid
component, based on the total moles of the diacid component; or (b)
the dihydroxy component may further comprise up to 20 mole percent,
preferably from 0.1 to 20 mole percent, preferably from 0.1 to 10
mole percent, of the total moles of the dihydroxy component of one
or more dihydroxy comonomers to modify, preferably increase,
T.sub.g, preferably wherein the one or more dihydroxy comonomers
comprises an aromatic dihydroxy comonomer, preferably resorcinol,
preferably wherein hydroquinone comprises at least 80 mole percent
of the dihydroxy component based on the total moles of the
dihydroxy component; or (c) a combination thereof; preferably
wherein the polyester comprises a nematic phase, an amorphous
morphology phase, or a combination thereof.
[0067] In any embodiment of the invention: (a) the diacid component
may further comprise up to 20 mole percent, preferably from 0.1 to
20 mole percent, preferably from 0.1 to 10 mole percent, of the
total moles of the diacid component of one or more diacid
comonomers to modify crystallinity of the polyester, preferably to
increase heat of fusion (.DELTA.H.sub.f), preferably wherein the
one or more diacid comonomers is selected from: terephthalic acid
(TA), naphthalene dicarboxylic acid (NDA), 4,4'-biphenyl
dicarboxylate (4,4'BB), hydroxybenzoic acid (HBA), and combinations
thereof, preferably wherein 3,4'-biphenyl dicarboxylate comprises
at least 80 mole percent of the diacid component, based on the
total moles of the diacid component; or (b) wherein the dihydroxy
component may further comprise up to 20 mole percent of the total
moles of the dihydroxy component of one or more dihydroxy
comonomers to modify crystallinity of the polyester, preferably to
increase heat of fusion (.DELTA.H.sub.f), preferably wherein the
one or more dihydroxy comonomers comprises an aromatic dihydroxy,
preferably 4,4-dihydroxybiphenyl, preferably wherein hydroquinone
comprises at least 80 mole percent of the dihydroxy component based
on the total moles of the dihydroxy component; or (c) a combination
thereof; preferably wherein the polyester comprises a smectic
phase, a semicrystalline morphology, or a combination thereof.
[0068] In any embodiment, the one or more aromatic dihydroxy
comonomers is selected from: resorcinol, 4,4-dihydroxybiphenyl, and
combinations thereof; the one or more aromatic diacid comonomers is
selected from: terephthalic acid (TA), naphthalene dicarboxylic
acid (NDA), 4,4'-biphenyl dicarboxylate (4,4'BB), isophthalic acid
(IA), and combinations thereof; and/or the hydroxy-carboxylic acid
comonomer, if present, is p-hydroxy benzoic acid.
[0069] In any embodiment of the invention, the polyester may
further exhibit a flow temperature (T.sub.f) less than a thermal
decomposition temperature (T.sub.d,5%), and/or an isotropic
temperature (T.sub.i) less than T.sub.d,5%.
[0070] In any embodiment of the invention, the polyester may
further exhibit: (a) a thermal decomposition temperature
(T.sub.d,5%) of about 400.degree. C. or more, preferably about
450.degree. C. or more, about 475.degree. C. or more, about
480.degree. C. or more, about 475.degree. C. to about 495.degree.
C., about 480.degree. C. to about 490.degree. C., or about
484.degree. C. to about 487.degree. C.; or (b) a flow temperature
(T.sub.f) of about 400.degree. C. or less, preferably about
350.degree. C. or less, about 300.degree. C. to about 350.degree.
C., about 310.degree. C. to about 340.degree. C., about 320.degree.
C. to about 330.degree. C., about 322.degree. C. to about
327.degree. C., or about 324.degree. C. to about 325.degree. C.; or
(c) an isotropic temperature (T.sub.i) of about 400.degree. C. or
less, preferably about 350.degree. C. or less, about 300.degree. C.
to about 350.degree. C., about 310.degree. C. to about 340.degree.
C., about 320.degree. C. to about 330.degree. C., about 322.degree.
C. to about 327.degree. C., or about 324.degree. C. to about
325.degree. C.; or (d) a glass transition temperature (T.sub.g) of
about 220.degree. C. or less, preferably about 175.degree. C. to
about 210.degree. C., about 180.degree. C. to about 205.degree. C.,
about 182.degree. C. to about 200.degree. C., about 184.degree. C.
to about 198.degree. C., about 182.degree. C. to about 186.degree.
C., about 184.degree. C., about 196.degree. C. to about 200.degree.
C., or about 198.degree. C.; or (e) a zero shear melt viscosity
(.eta.*) at 340.degree. C. of at least about 50,000 Pa-s,
preferably at least about 75,000 Pa-s, at least about 100,000 Pa-s,
at least about 1,000,000 Pa-s, at least about 2,000,000 Pa-s, about
50,000 Pa-s to about 5,000,000 Pa-s, about 75,000 Pa-s to about
3,500,000 Pa-s, about 100,000 Pa-s to about 2,500,000 Pa-s, about
100,000 Pa-s, or about 2,500,000 Pa-s; or a combination of any or
all thereof.
[0071] In any embodiment of the invention, a method may comprise
contacting a dihydroxy component comprising at least about 80 mole
percent of hydroquinone or an ester forming hydroquinone
derivative, with a diacid component comprising at least about 80
mole percent of 3,4'-biphenyl dicarboxylic acid (3,4'-BB) or an
ester-forming derivative of 3,4'-BB, and optionally with a
hydroxy-carboxylic acid component in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-carboxylic acid component, under polycondensation
conditions; forming a polyester comprising the dihydroxy and diacid
components and any hydroxy-carboxylic acid component; and
processing the polyester in a liquid crystalline glass phase.
Generally, the method may be used to form the polyester of any
embodiment described herein.
[0072] In any embodiment of the method, the polyester may
preferably consist essentially of, or consist of, hydroquinone and
3,4'-biphenyl dicarboxylate, e.g., the dihydroxy component can
consist of hydroxyquinone and the diacid component can consist of
3,4-biphenyl dicarboxylate. In any embodiment of the method, the
polyester can be free of or essentially free of the
hydroxy-carboxylic acid component.
[0073] In any embodiment of the method, the dihydroxy component may
comprise, consist essentially of, or preferably consist of the
hydroquinone derivative, preferably wherein the hydroquinone
derivative comprises a carboxylic acid or anhydride addition
diester, preferably wherein the carboxylic acid comprises from 1 to
6 carbon atoms, preferably from 1 to 4 carbon atoms, or wherein the
carboxylic acid anhydride comprises from 2 to 12 carbon atoms,
preferably 2 to 8 carbon atoms, preferably wherein the hydroquinone
derivative is hydroquinone alkanoate, preferably hydroquinone
diacetate, hydroquinone dipivalate, or a combination thereof. In
any embodiment of the method the dihydroxy component may comprise,
consist essentially of, or consist of the hydroquinone derivative,
preferably wherein the hydroquinone derivative comprises the
reaction product of a hydroquinone with a carboxylic acid,
preferably an alkyl carboxylic acid comprising from 1 to 6 carbon
atoms, preferably an alkyl carboxylic acid comprising 1 to 4 carbon
atoms, or an anhydride comprising from 2 to 14 carbon atoms,
preferably 2 to 8 carbon atoms, to form the hydroquinone diester,
preferably wherein the hydroquinone diester is hydroquinone
dialkanoate, preferably hydroquinone diacetate, hydroquinone
dipivalate, or a combination thereof.
[0074] In any embodiment of the method, the diacid component may
comprise, consist essentially of, or preferably consist of 3,4'-BB,
preferably in the free acid form.
[0075] In any embodiment of the method, the dihydroxy component,
the diacid component, or both the dihydroxy and diacid components,
may further comprise one or more comonomers in an amount effective
to: modify crystallinity, preferably increase crystallinity; modify
heat of fusion (.DELTA.H.sub.f), preferably increase heat of
fusion; modify glass transition temperature (T.sub.g), preferably
increase T.sub.g; modify thermal decomposition temperature
(T.sub.d,5%), preferably increase T.sub.d,5%; modify flow
temperature (T.sub.f), preferably decrease T.sub.f; modify
isotropic temperature (T.sub.i), preferably increase T.sub.i;
modify zero shear melt viscosity (.eta.') at 340.degree. C.,
preferably decrease .eta.*; or modify a combination thereof; of the
polyester formed. Preferably, the one or more comonomers are
aromatic.
[0076] In any embodiment of the method: (a) the dihydroxy component
may comprise one or more dihydroxy component comonomers, preferably
in an amount up to 20 mole percent, preferably from 0.1 to 20 mole
percent, more preferably from 0.1 to 10 mole percent, of the total
moles of the dihydroxy component, preferably wherein hydroquinone
or a derivative thereof comprises at least 80 mole percent of the
dihydroxy component based on the total moles of the dihydroxy
component; (b) the diacid component may comprise one or more diacid
component comonomers in an amount up to 20 mole percent, preferably
from 0.1 to 20 mole percent, more preferably from 0.1 to 10 mole
percent, of the total moles of the diacid component, preferably
wherein 3,4'-biphenyl dicarboxylate comprises at least 80 mole
percent of the diacid component, based on the total moles of the
diacid component; or (c) a combination thereof. Preferably, the one
or more comonomers are aromatic.
[0077] In any embodiment of the method: (a) the dihydroxy component
further comprises up to 20 mole percent, preferably from 0.1 to 20
mole percent, more preferably from 0.1 to 10 mole percent, of the
total moles of the dihydroxy component, of a dihydroxy comonomer,
preferably an aromatic dihydroxy comonomer, preferably selected
from: resorcinol, 4,4-dihydroxybiphenyl, and derivatives and
combinations thereof; or (b) the diacid component may further
comprise up to 20 mole percent, preferably from 0.1 to 20 mole
percent, more preferably from 0.1 to 10 mole percent, of the total
moles of the diacid component, of a diacid comonomer, preferably an
aromatic diacid comonomer, preferably selected from: terephthalic
acid (TA), naphthalene dicarboxylic acid (NDA), 4,4'-biphenyl
dicarboxylate (4,4'BB), hydroxybenzoic acid (HBA), isophthalic acid
(IA), and combinations thereof.
[0078] In any embodiment of the method: (a) the diacid component
may further comprise up to 20 mole percent, preferably from 0.1 to
20 mole percent, preferably from 0.1 to 10 mole percent, of the
total moles of the diacid component of one or more diacid
comonomers to modify T.sub.g, preferably to increase T.sub.g,
preferably wherein the one or more diacid comonomers comprises
isophthalic acid (IA), preferably wherein 3,4'-biphenyl
dicarboxylate comprises at least 80 mole percent of the diacid
component, based on the total moles of the diacid component; or (b)
the dihydroxy component may further comprise up to 20 mole percent,
preferably from 0.1 to 20 mole percent, preferably from 0.1 to 10
mole percent, of the total moles of the dihydroxy component of one
or more dihydroxy comonomers to modify, preferably increase,
T.sub.g, of the polyester formed, preferably wherein the one or
more dihydroxy comonomers comprises an aromatic dihydroxy
comonomer, preferably resorcinol or a derivative thereof,
preferably wherein hydroquinone or a derivative thereof comprises
at least 80 mole percent of the dihydroxy component based on the
total moles of the dihydroxy component; or (c) a combination
thereof; preferably wherein the polyester comprises a nematic
phase, an amorphous morphology phase, or a combination thereof.
[0079] In any embodiment of the method: (a) the diacid component
may further comprise up to 20 mole percent, preferably from 0.1 to
20 mole percent, preferably from 0.1 to 10 mole percent, of the
total moles of the diacid component of one or more diacid
comonomers to modify crystallinity of the polyester formed,
preferably to increase heat of fusion (.DELTA.H.sub.f), preferably
wherein the one or more diacid comonomers is selected from:
terephthalic acid (TA), naphthalene dicarboxylic acid (NDA),
4,4'-biphenyl dicarboxylate (4,4'BB), hydroxybenzoic acid (HBA),
and combinations thereof, preferably wherein 3,4'-biphenyl
dicarboxylate comprises at least 80 mole percent of the diacid
component, based on the total moles of the diacid component; or (b)
wherein the dihydroxy component further comprises up to 20 mole
percent of the total moles of the dihydroxy component of one or
more dihydroxy comonomers to modify crystallinity of the polyester
formed, preferably to increase heat of fusion (.DELTA.H.sub.f),
preferably wherein the one or more dihydroxy comonomers comprises
an aromatic dihydroxy, preferably 4,4-dihydroxybiphenyl or a
derivative thereof, preferably wherein hydroquinone or a derivative
thereof comprises at least 80 mole percent of the dihydroxy
component based on the total moles of the dihydroxy component; or
(c) a combination thereof; preferably wherein the polyester formed
comprises a smectic phase, a semicrystalline morphology, or a
combination thereof.
[0080] In any embodiment of the method, the one or more comonomers
may be aromatic, cycloaliphatic, non-cyclic aliphatic, or a
combination thereof, preferably aromatic.
[0081] In any embodiment of the method, the polyester formation may
be by acidolysis polycondensation.
[0082] In any embodiment of the invention, the method may further
comprise hydrolyzing a 3,4'-bibenzoate diester to form the 3,4'-BB,
followed by acidification to form the 3,4'-BB free acid, preferably
wherein the diester comprises dialkyl 3,4'-bibenzoate, more
preferably dimethyl 3,4'-bibenzoate. Preferably, the hydrolysis
comprises refluxing the 3,4'-bibenzoate diester in an alkaline
solvent, preferably aqueous sodium hydroxide, followed by
acidification with a mineral acid, e.g., HCl.
[0083] In any embodiment of the invention, the method may further
comprise esterifying hydroquinone with the ester-forming
hydrocarbyl, preferably the carboxylic acid, carboxylic acid
anhydride, or combination thereof, more preferably the acetic acid,
acetic anhydride, pivalic acid, pivalic anhydride, or combination
thereof, to form the hydroquinone derivative comprising
hydroquinone diester. Esterification may be accomplished by adding
an ester-forming hydrocarbyl, such as acetic anhydride to the
hydroquinone and/or other monomers. Acetylation, for example, is
generally achieved with an excess of from about 1 to about 10 mole
percent of acetic anhydride, usually with an esterification
catalyst, at temperatures of from about 90.degree. C. to
150.degree. C., optionally with reflux to retain residual acetic
anhydride in the reaction. Acetylation may occur in a separate
reactor vessel, or it may occur in situ within the polymerization
reactor vessel. The esterification catalyst may be the same or
different as the polycondensation catalyst.
[0084] In any embodiment of the invention, the method may further
comprise purifying the hydroquinone derivative, preferably by
recrystallization.
[0085] In any embodiment of the invention, the method may further
comprise melt processing the polyester. Preferably, the method
further comprises cooling the polyester from the melt to form a
liquid crystalline glass phase, preferably a nematic mesophase or a
smectic mesophase. In any embodiment, the method may further
comprise forming the polyester into a shaped article, preferably a
fiber, a nonwoven fabric, a film, or a molded article.
[0086] In any embodiment of the present invention, the polyesters
can have a number average molecular weight of equal to or greater
than about 5,000 g/mol (or equal to or greater than 8,000, or equal
to or greater than 10,000, or equal to or greater than 12,000, or
equal to or greater than 15,000, or equal to or greater than
20,000, or equal to or greater than 30,000, or equal to or greater
than 40,000, or equal to or greater than 50,000 g/mol); and/or a
polydispersity of greater than 1.75 up to 3.5 (or from 1.8 up to 3,
or from 1.8 to 2.5, or from 1.9 to 2.5, or about 2.0) where Mn and
polydispersity are determined by GPC or calculated from the
inherent viscosity. In the event of a conflict, the calculation
from inherent viscosity shall control. In any embodiment of the
invention, the polyester preferably exhibits an inherent viscosity
equal to or greater than about 0.5 dL/g, or equal to or greater
than 0.7 dL/g, or equal to or greater than 0.8 dL/g; and/or less
than or equal to about 1 dL/g, or less than or equal to about 0.9
dL/g.
[0087] In any embodiment, the polyesters preferably have a glass
transition temperature equal to or greater than about 160.degree.
C., or greater than about 170.degree. C., or greater than about
180.degree. C., or greater than about 190.degree. C., or about
194.degree. C.
[0088] Often, the polyesters can exhibit an essentially amorphous
morphology, e.g., the polymer does not exhibit a measurable
crystallization temperature T.sub.c and/or does not exhibit a
discernable melting temperature T.sub.m.
[0089] Often, the polyesters can exhibit a semicrystalline
morphology. In any embodiment, the polymer preferably comprises
relative amounts of 3,4'-biphenyl dicarboxylate and diacid
comonomer(s) sufficient to produce a melting point peak, a
crystallization point peak, or both. When the polyester is
semi-crystalline, it preferably has a melting point of less than
the T.sub.d,5%, preferably a melting point of about 320.degree. C.
or less.
[0090] Often, the polyester copolymer can exhibit less than or
equal to about 20 weight percent crystallinity, or less than or
equal to about 10 weight percent crystallinity, or less than or
equal to about 5 weight percent crystallinity, or less than or
equal to about 1 weight percent crystallinity, determined by DSC
analysis from a second heating ramp at a heating rate of 10.degree.
C./min.
[0091] It is expected that the polyesters according to the present
invention have a flexural modulus greater than 4800 MPa when
determined according to ASTM D638; and/or a flexural strength
greater than 170 MPa when determined according to ASTM D638; and/or
a tensile modulus of greater than 4700 MPa, when determined
according to ASTM D638; and/or a tensile strength at maximum load
of greater than 70 MPa, when determined according to ASTM D638;
and/or a tensile strain to failure of greater than 1.8%.
[0092] In any embodiment of the invention, the polyesters may be
prepared by melt polymerization techniques including
transesterification and polycondensation, in batch, semi-batch, or
continuous processes. The polyesters are preferably prepared in a
reactor equipped with a stirrer, an inert gas (e.g., nitrogen)
inlet, a thermocouple, a distillation column connected to a
water-cooled condenser, a water separator, and a vacuum connection
tube. For example, the equipment and procedures disclosed in U.S.
Pat. Nos. 4,093,603 and 5,681,918, incorporated by reference
herein, may be adapted for implementing the present invention.
[0093] In any embodiment, polycondensation processes may include
melt phase processes conducted with the introduction of an inert
gas stream, such as nitrogen, to shift the equilibrium and advance
to high molecular weight and/or vacuum melt phase polycondensation,
preferably acid hydrolysis polycondensation, at temperatures above
about 150.degree. C., preferably above about 300.degree. C., and
pressures below about 130 Pa (1 mm Hg). The esterification
conditions can generally include a temperature which is gradually
increased from about 300.degree. C. in the initial reaction steps
up to about 330 to 360.degree. C. in the later steps, initially
under normal pressure, then, when necessary, under reduced pressure
at the end of each step, while maintaining these operating
conditions until a polyester with the desired properties is
obtained. The acid hydrolysis polycondensation is preferably
conducted without catalysts or stabilizers, but if desired the
esterification conditions may include an optional esterification
catalyst, preferably in an amount from about 0.05 to 1.5 percent by
weight of the reactants; optional stabilizers, such as, for
example, phenolic antioxidants such as IRGANOX 1010 or phosphonite-
and phosphite-type stabilizers such as tributylphosphite,
preferably in an amount from 0 to 1 percent by weight of the
reactants. If desired, the degree of esterification may be
monitored by measuring the amount of hydroquinone esterification
acid (e.g., acetic acid or pivalic acid) formed and the properties
of the polyester, for example, viscosity, hydroxyl number, acid
number, and so on. In embodiments, the catalyst comprises from 0.05
to 1.5 wt % of an alkyl acid salt, preferably a Group I salt of an
alkyl acid comprising from 1 to 6 carbon atoms, preferably sodium
acetate, potassium acetate, sodium pivalate potassium pivalate, or
a combination thereof.
[0094] In general, the polyesters may include conventional
additives including pigments, colorants, stabilizers, antioxidants,
extrusion aids, reheat agents, slip agents, carbon black, flame
retardants, and mixtures thereof. In any embodiment, the polyester
may be combined or blended with one or more modifiers and/or blend
polymers including polyamides; e.g., NYLON 6,6.RTM. (DuPont),
poly(ether-imides), polyphenylene oxides, e.g.,
poly(2,6-dimethylphenylene oxide), poly(phenylene
oxide)/polystyrene blends; e.g., NORYL.RTM. (SABIC Innovative
Plastics), other polyesters, polyphenylene sulfides, polyphenylene
sulfide/sulfones, poly(ester-carbonates), polycarbonates; e.g.,
LEXAN.RTM. (SABIC Innovative Plastics), polysulfones, polysulfone
ethers, poly(ether-ketones), combinations thereof, and the
like.
[0095] Any of the polyesters and compositions described herein may
be used in the preparation of molded products in any molding
process, including but not limited to, injection molding,
gas-assisted injection molding, extrusion blow molding, injection
blow molding, injection stretch blow molding, compression molding,
rotational molding, foam molding, thermoforming, sheet extrusion,
and profile extrusion. The molding processes are well known to
those of ordinary skill in the art. The polyester compositions
described above may also be used in the preparation of nonwoven
fabrics and fibers. In any embodiment, a shaped article such as an
extruded profile or an extruded or injection molded article can
comprise one or more polyesters according to one or more
embodiments disclosed herein. Accordingly, in any embodiment,
polyesters according to the instant invention can generally be
molded and extruded using conventional melt processing techniques
to produce a shaped article. Such articles may exhibit
birefringence. Such articles may be transparent. The shaped
articles manufactured from the polyesters disclosed herein
generally exhibit birefringence and/or other improved properties as
shown in the examples below.
[0096] Shaped articles comprising any embodiment of the polymers
disclosed herein may generally be produced using thermoplastic
processing procedures such as injection molding, calendaring,
extrusion, blow molding, extrusion blow molding, rotational
molding, and so on. The amorphous and/or semicrystalline
(co)polyesters of the present invention preferably exhibit improved
stability at various melt temperatures. In the conversion of the
polyesters into shaped articles, the carboxylic acid content of
polyesters according to the present invention may often be reduced
to less than about 0.02 percent prior to melt processing.
Embodiments
[0097] The present invention provides the following
embodiments:
1. A polyester comprising: [0098] a dihydroxy component comprising
at least about 80 mole percent of hydroquinone, based on the total
moles of the dihydroxy component; and [0099] a diacid component
comprising at least about 80 mole percent of 3,4'-biphenyl
dicarboxylate, based on the total moles of the diacid component;
[0100] an optional hydroxy-carboxylic acid component in an amount
up to 20 mole percent, based on the total moles of the diacid
component and the hydroxy-carboxylic acid component. 2. The
polyester of embodiment 1, wherein the polyester is a liquid
crystalline polyester having a flow temperature (T.sub.f) as
determined by ASTM D4065 at 1 Hz below an isotropic temperature
(T.sub.i) determined by DSC with a heat/cool/heat cycle (second
heating) at a heating rate of 10.degree. C./min and cooling rate of
100.degree. C./min. 3. The polyester of embodiment 1 or embodiment
2, wherein the polyester exhibits birefringence and/or anisotropy,
preferably wherein the polyester comprises a liquid crystalline
glass phase comprising poly(hydroquinone-3,4'-biphenyl
dicarboxylate), or more preferably a nematic mesophase or a smectic
mesophase comprising poly(hydroquinone-3,4'-biphenyl
dicarboxylate). 4. The polyester of embodiment 1 or embodiment 2,
consisting essentially of or consisting of hydroquinone and
3,4'-biphenyl dicarboxylate. 5. The polyester of any preceding
embodiment, wherein the dihydroxy component consists of
hydroquinone, and the diacid component consists of 3,4'-biphenyl
dicarboxylate. 6. The polyester of any preceding embodiment,
wherein the polyester is free of the hydroxy-carboxylic acid
component. 7. The polyester of any preceding embodiment, further
comprising one or more comonomers in an amount effective to modify:
crystallinity as determined by ASTM D3418; heat of fusion
(.DELTA.H.sub.f) as determined by ASTM D341; glass transition
temperature (T.sub.g), as determined by ASTM D3418; thermal
decomposition temperature (T.sub.d,5%) as determined by ASTM D3850
using a temperature ramp of 10.degree. C./min under nitrogen; the
T.sub.f; the T.sub.i; zero shear melt viscosity (.eta.*) determined
at 340.degree. C. at a frequency of 0.1 radians/second, by
frequency sweep on 8 mm parallel plates under nitrogen at 1%
strain; or a combination thereof. 8. The polyester of embodiment 7,
further comprising one or more of the following: wherein the
dihydroxy component comprises one or more aromatic dihydroxy
component comonomers in an amount up to 20 mole percent, based on
the total moles of the dihydroxy component; wherein the diacid
component comprises one or more aromatic diacid component
comonomers in an amount up to 20 mole percent, based on the total
moles of the diacid component; wherein the polyester comprises a
hydroxy-carboxylic acid comonomer in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-acid comonomer. 9. The polyester of embodiment 8, further
comprising one or more of the following: wherein the one or more
aromatic dihydroxy comonomers is selected from: resorcinol,
4,4-dihydroxybiphenyl, and combinations thereof; wherein the one or
more aromatic diacid comonomers is selected from: terephthalic acid
(TA), naphthalene dicarboxylic acid (NDA), 4,4'-biphenyl
dicarboxylate (4,4'BB), isophthalic acid (IA), and combinations
thereof; wherein the hydroxy-carboxylic acid comonomer is p-hydroxy
benzoic acid. 10. The polyester of any preceding embodiment,
wherein the T.sub.i is less than the thermal decomposition
temperature (T.sub.d,5%) as determined by ASTM D3850 using a
temperature ramp of 10.degree. C./min under nitrogen. 11. The
polyester of any preceding embodiment, wherein the polyester
exhibits one or more of the following: a thermal decomposition
temperature (T.sub.d,5%) as determined by ASTM D3850 using a
temperature ramp of 10.degree. C./min under nitrogen, of about
400.degree. C. or more; the T.sub.f is about 350.degree. C. or
less; the T.sub.i is about 350.degree. C. or less; a glass
transition temperature (T.sub.g) as determined by ASTM D3418, of
about 220.degree. C. or less; a zero-shear melt viscosity (.eta.*)
determined at 340.degree. C. at a frequency of 0.1 radians/second,
by frequency sweep on 8 mm parallel plates under nitrogen at 1.25%
strain, of at least about 50,000 Pa-s. 12. The polyester of any
preceding embodiment, further comprising one or more or all of the
following: [0101] wherein the dihydroxy component, the diacid
component, or both the dihydroxy and diacid components further
comprise: one or more comonomers in an amount effective to modify
(preferably increase) crystallinity, as determined by ASTM D3418,
[0102] wherein the dihydroxy component, the diacid component, or
both the dihydroxy and diacid components further comprise: one or
more comonomers in an amount effective to modify (preferably
increase) heat of fusion (.DELTA.H.sub.f) as determined by ASTM
D341, [0103] wherein the dihydroxy component, the diacid component,
or both the dihydroxy and diacid components further comprise: one
or more comonomers in an amount effective to modify (preferably
increase) glass transition temperature (T.sub.g), as determined by
ASTM D3418, [0104] wherein the dihydroxy component, the diacid
component, or both the dihydroxy and diacid components further
comprise: one or more comonomers in an amount effective to modify
(preferably increase) thermal decomposition temperature
(T.sub.d,5%) as determined by ASTM D3850 using a temperature ramp
of 10.degree. C./min under nitrogen, [0105] wherein the dihydroxy
component, the diacid component, or both the dihydroxy and diacid
components further comprise: one or more comonomers in an amount
effective to modify (preferably decrease) flow temperature (Tf) as
determined by ASTM D4065 at 1 Hz, [0106] wherein the dihydroxy
component, the diacid component, or both the dihydroxy and diacid
components further comprise: one or more comonomers in an amount
effective to modify (preferably decrease) isotropic temperature
(Ti) as determined by ASTM D3418, and/or [0107] wherein the
dihydroxy component, the diacid component, or both the dihydroxy
and diacid components further comprise: one or more comonomers in
an amount effective to modify (preferably decrease) zero shear melt
viscosity (.eta.*) determined at 340.degree. C. at a frequency of
0.1 radians/second, by frequency sweep on 8 mm parallel plates
under nitrogen at 1% strain. 13. The polyester of embodiment 12
wherein the one or more comonomers are aromatic. 14. The polyester
of any preceding embodiment, further comprising wherein (a) the
dihydroxy component comprises one or more dihydroxy component
comonomers in an amount up to 20 mole percent, preferably from 0.1
to 20 mole percent, more preferably from 0.1 to 10 mole percent, of
the total moles of the dihydroxy component, preferably wherein
hydroquinone comprises at least 80 mole percent of the dihydroxy
component based on the total moles of the dihydroxy component; (b)
the diacid component comprises one or more diacid component
comonomers in an amount up to 20 mole percent, preferably from 0.1
to 20 mole percent, more preferably from 0.1 to 10 mole percent, of
the total moles of the diacid component, preferably wherein
3,4'-biphenyl dicarboxylate comprises at least 80 mole percent of
the diacid component based on the total moles of the diacid
component; or (c) a combination thereof; preferably wherein the one
or more comonomers are aromatic. 15. The polyester of any preceding
embodiment, further comprising one or both of the following: [0108]
wherein the dihydroxy component further comprises up to 20 mole
percent, preferably from 0.1 to 20 mole percent, more preferably
from 0.1 to 10 mole percent, of the total moles of the dihydroxy
component, of a dihydroxy comonomer, preferably an aromatic
dihydroxy comonomer, preferably selected from: resorcinol,
4,4-dihydroxybiphenyl, and combinations thereof, preferably wherein
hydroquinone comprises at least 80 mole percent of the dihydroxy
component based on the total moles of the dihydroxy component;
and/or [0109] wherein the diacid component further comprises up to
20 mole percent, preferably from 0.1 to 20 mole percent, more
preferably from 0.1 to 10 mole percent, of the total moles of the
diacid component, of a diacid comonomer, preferably an aromatic
diacid comonomer, preferably selected from: terephthalic acid (TA),
naphthalene dicarboxylic acid (NDA), 4,4'-biphenyl dicarboxylate
(4,4'BB), hydroxybenzoic acid (HBA), isophthalic acid (IA), and
combinations thereof, preferably wherein 3,4'-biphenyl
dicarboxylate comprises at least 80 mole percent of the diacid
component based on the total moles of the diacid component. 16. The
polyester of any preceding embodiment, further comprising one or
both of the following: [0110] wherein the diacid component further
comprises up to 20 mole percent, preferably from 0.1 to 20 mole
percent, preferably from 0.1 to 10 mole percent, of the total moles
of the diacid component of one or more diacid comonomers to modify
(preferably increase) glass transition temperature (T.sub.g) as
determined by ASTM D3418, preferably wherein the one or more diacid
comonomers comprises isophthalic acid (IA), preferably wherein
3,4'-biphenyl dicarboxylate comprises at least 80 mole percent of
the diacid component based on the total moles of the diacid
component; and/or [0111] wherein the dihydroxy component further
comprises up to 20 mole percent, preferably from 0.1 to 20 mole
percent, of the total moles of the dihydroxy component of one or
more dihydroxy comonomers to modify (preferably increase) glass
transition temperature (T.sub.g) as determined by ASTM D3418,
preferably wherein the one or more dihydroxy comonomers comprises
an aromatic dihydroxy comonomer, preferably resorcinol, preferably
wherein hydroquinone comprises at least 80 mole percent of the
dihydroxy component based on the total moles of the dihydroxy
component. 17. The polyester of embodiment 16 wherein the polyester
comprises a nematic phase, an amorphous morphology phase, or a
combination thereof. 18. The polyester of any preceding embodiment,
further comprising one or both of the following: [0112] wherein the
diacid component further comprises up to 20 mole percent,
preferably from 0.1 to 20 mole percent, preferably from 0.1 to 10
mole percent, of the total moles of the diacid component of one or
more diacid comonomers to modify crystallinity of the polyester,
preferably to increase heat of fusion (.DELTA.H.sub.f) as
determined by ASTM D3418, preferably wherein the one or more diacid
comonomers is selected from: terephthalic acid (TA), naphthalene
dicarboxylic acid (NDA), 4,4'-biphenyl dicarboxylate (4,4'BB),
hydroxybenzoic acid (HBA), and combinations thereof, preferably
wherein 3,4'-biphenyl dicarboxylate comprises at least 80 mole
percent of the diacid component based on the total moles of the
diacid component; and/or [0113] wherein the dihydroxy component
further comprises up to 20 mole percent of the total moles of the
dihydroxy component of one or more dihydroxy comonomers to modify
crystallinity of the polyester, preferably to increase heat of
fusion (.DELTA.H.sub.f) as determined by ASTM D3418, preferably
wherein the one or more dihydroxy comonomers comprises an aromatic
dihydroxy, preferably 4,4-dihydroxybiphenyl, preferably wherein
hydroquinone comprises at least 80 mole percent of the dihydroxy
component based on the total moles of the dihydroxy component. 19.
The polyester of embodiment 18 wherein the polyester comprises a
smectic phase, a semicrystalline morphology, or a combination
thereof. 20. The polyester of any preceding embodiment, further
exhibiting a flow temperature (T.sub.f) as determined by ASTM D4065
at 1 Hz, less than a thermal decomposition temperature (T.sub.d,5%)
as determined by ASTM D3850 using a temperature ramp of 10.degree.
C./min under nitrogen. 21. The polyester of any preceding
embodiment, further exhibiting an isotropic temperature (T.sub.i)
as determined by ASTM D3418 less than the thermal decomposition
temperature (T.sub.d,5%) as determined by ASTM D3850 using a
temperature ramp of 10.degree. C./min under nitrogen. 22. The
polyester of any preceding embodiment, wherein the polyester
exhibits one or more or all of the following: [0114] a thermal
decomposition temperature (T.sub.d,5%) as determined by ASTM D3850
using a temperature ramp of 10.degree. C./min under nitrogen, of
about 400.degree. C. or more, preferably about 450.degree. C. or
more, about 475.degree. C. or more, or about 480.degree. C. or
more; [0115] a flow temperature (T.sub.f) as determined by ASTM
D4065 at 1 Hz, of about 400.degree. C. or less, preferably about
350.degree. C. or less, or about 300.degree. C. to about
350.degree. C.; [0116] an isotropic temperature (T.sub.i) as
determined by ASTM D3418, of about 400.degree. C. or less,
preferably about 350.degree. C. or less, or about 300.degree. C. to
about 350.degree. C.; [0117] a glass transition temperature
(T.sub.g) as determined by ASTM D3418, of about 220.degree. C. or
less, preferably about 175.degree. C. to about 210.degree. C., or
about 180.degree. C. to about 205.degree. C.; [0118] a zero-shear
melt viscosity (.eta.*) determined at 340.degree. C. at a frequency
of 0.1 radians/second, by frequency sweep on 8 mm parallel plates
under nitrogen at 1% strain, of at least about 50,000 Pa-s,
preferably at least about 75,000 Pa-s, at least about 100,000 Pa-s,
at least about 1,000,000 Pa-s, or at least about 2,000,000 Pa-s.
23. The polyester of any preceding embodiment, wherein the
polyester exhibits one or more or all of the following: [0119] a
thermal decomposition temperature (T.sub.d,5%) as determined by
ASTM D3850 using a temperature ramp of 10.degree. C./min under
nitrogen, of about 475.degree. C. to about 495.degree. C.,
preferably about 480.degree. C. to about 490.degree. C., or about
484.degree. C. to about 487.degree. C.; [0120] a flow temperature
(T.sub.f) as determined by ASTM D4065 at 1 Hz, of about 300.degree.
C. to about 350.degree. C., preferably about 310.degree. C. to
about 340.degree. C., about 320.degree. C. to about 330.degree. C.,
about 322.degree. C. to about 327.degree. C., or about 324.degree.
C. to about 325.degree. C.; [0121] an isotropic temperature
(T.sub.i) as determined by ASTM D3418, of about 310.degree. C. to
about 340.degree. C., preferably about 320.degree. C. to about
330.degree. C., about 322.degree. C. to about 327.degree. C., or
about 324.degree. C. to about 325.degree. C.; [0122] a glass
transition temperature (T.sub.g) as determined by ASTM D3418, of
about 180.degree. C. to about 205.degree. C., preferably about
182.degree. C. to about 200.degree. C., about 184.degree. C. to
about 198.degree. C., about 182.degree. C. to about 186.degree. C.,
about 184.degree. C., about 196.degree. C. to about 200.degree. C.,
or about 198.degree. C.; [0123] a zero-shear melt viscosity
(.eta.
*) determined at 340.degree. C. at a frequency of 0.1
radians/second, by frequency sweep on 8 mm parallel plates under
nitrogen at 1% strain, of about 50,000 Pa-s to about 5,000,000
Pa-s, preferably about 75,000 Pa-s to about 3,500,000 Pa-s, about
100,000 Pa-s to about 2,500,000 Pa-s, about 100,000 Pa-s, or about
2,500,000 Pa-s. 24. A method comprising: [0124] contacting a
dihydroxy component comprising at least about 80 mole percent of
hydroquinone or a hydroquinone diester derivative, based on the
total moles of the dihydroxy component, with a diacid component
comprising at least about 80 mole percent of 3,4'-biphenyl
dicarboxylic acid (3,4'-BB) or an ester derivative of 3,4'-BB,
based on the total moles of the diacid component, and optionally
with a hydroxy-carboxylic acid component in an amount up to 20 mole
percent, based on the total moles of the diacid component and the
hydroxy-carboxylic acid component, under polycondensation
conditions; and [0125] forming a polyester comprising the dihydroxy
and diacid components; or preferably forming the polyester of any
of embodiments 1 to 23. 25. The method of embodiment 24, further
comprising processing the polyester in a liquid crystalline glass
phase. 26. The method of embodiment 24 or embodiment 25, wherein
the polyester consists essentially of hydroquinone and
3,4'-biphenyl dicarboxylate. 27. The method of any of embodiments
24 to 26, wherein the dihydroxy component consists of hydroquinone,
and the diacid component consists of 3,4'-biphenyl dicarboxylate.
28. The method of any of embodiments 24 to 27, wherein the
polyester is free of the hydroxy-carboxylic acid component. 29. The
method of any of embodiments 24 to 28, wherein the dihydroxy
component comprises the hydroquinone diester derivative comprising
the reaction product of a hydroquinone with a carboxylic acid
comprising from 1 to 6 carbon atoms or an anhydride comprising from
2 to 14 carbon atoms, to form the hydroquinone diester derivative.
30. The method of embodiment 29, wherein the hydroquinone diester
derivative is hydroquinone dipivalate. 31. The method of any of
embodiments 24 to 30, wherein the diacid component comprises
3,4'-BB in the free acid form. 32. The method of any of embodiments
24 to 31, wherein the polyester further comprises one or more
comonomers in an amount effective to modify: crystallinity as
determined by ASTM D3418; heat of fusion (.DELTA.H.sub.f) as
determined by ASTM D341; glass transition temperature (T.sub.g), as
determined by ASTM D3418; thermal decomposition temperature
(T.sub.d,5%) as determined by ASTM D3850 using a temperature ramp
of 10.degree. C./min under nitrogen; the T.sub.f; the T.sub.i; zero
shear melt viscosity (.eta.*) determined at 340.degree. C. at a
frequency of 0.1 radians/second, by frequency sweep on 8 mm
parallel plates under nitrogen at 1% strain; or a combination
thereof. 33. The method of embodiment 32, further comprising one or
more of: wherein the dihydroxy component comprises one or more
aromatic dihydroxy component comonomers in an amount up to 20 mole
percent, based on the total moles of the dihydroxy component;
wherein the diacid component comprises one or more aromatic diacid
component comonomers in an amount up to 20 mole percent, based on
the total moles of the diacid component; wherein the polyester
comprises a hydroxy-carboxylic acid comonomer in an amount up to 20
mole percent, based on the total moles of the diacid component and
the hydroxy-acid comonomer. 34. The method of embodiment 33,
further comprising one or more of the following: wherein the one or
more aromatic dihydroxy comonomers is selected from: resorcinol,
4,4-dihydroxybiphenyl, and combinations thereof; wherein the one or
more aromatic diacid comonomers is selected from: terephthalic acid
(TA), naphthalene dicarboxylic acid (NDA), 4,4'-biphenyl
dicarboxylate (4,4'BB), isophthalic acid (IA), and combinations
thereof; wherein the hydroxy-carboxylic acid comonomer is p-hydroxy
benzoic acid. 35. The method of any of embodiments 24 to 34,
wherein the polyester formation is by acidolysis polycondensation.
36. The method of embodiment 35, further comprising hydrolyzing a
3,4'-bibenzoate diester to form the 3,4'-BB free acid. 37. The
method of embodiment 35 or embodiment 36, further comprising
esterifying hydroquinone with an ester-forming carboxylic acid,
carboxylic acid anhydride, or combination thereof. 38. The method
embodiment 37, wherein the carboxylic acid or anhydride is selected
from acetic acid, acetic anhydride, pivalic acid, pivalic
anhydride, or a combination thereof. 39. The method of any of
embodiments 24 to 38, further comprising forming the polyester into
a shaped article. 40. The method of embodiment 39, wherein the
shaped article comprises a fiber, a nonwoven fabric, a film, or a
molded article.
EXAMPLES
[0126] In the following examples, dimethyl 3,4'-biphenyl
dicarboxylate (3,4'BB) was supplied by EXXONMOBIL. Pivalic
anhydride (>99%) and hydroquinone diacetate were purchased from
Sigma-Aldrich. All solvents, nitrogen gas (Praxair, 99.999%), and
other gases were obtained from commercial sources and used as
received. All other solvents were obtained from Spectrum Chemicals
and used as received.
[0127] NMR analysis:
[0128] .sup.1H and .sup.13C NMR spectra were acquired on a VARIAN
UNITY 400 (400 MHz) instrument at 23.degree. C. in DMSO-d6 and
CDCl.sub.3, and the polymer required TFA-d.
[0129] Thermal Characterization:
[0130] The thermal stability of polymers was demonstrated through
thermal gravimetric analysis (TGA) using a Q50 instrument (TA
Instruments, New Castle, Del.). A one-step weight loss profile was
obtained using a temperature ramp of 10.degree. C./min from 25 to
600.degree. C. under nitrogen. Differential scanning calorimetry
(DSC) was performed on a Q1000 instrument (TA Instruments, New
Castle, Del.), calibrated with indium and zinc standards, using a
heat/cool/heat cycle (second heating) at a heating rate of
10.degree. C./min and cooling rate of 100.degree. C./min. Data
analysis occurred on the second heat cycles using the inflection
point of the T.sub.g and the maximum of the T.sub.i and
T.sub.m.
[0131] Compression Molding:
[0132] Compression molding of the polymers utilized a sandwich of
aluminum plates, Kapton.RTM. sheets coated with a REXCO
PARTALL.RTM. Power Glossy Liquid mold release agent, and 400 .mu.m
thick stainless-steel shims between which the samples were placed.
Heating above the T.sub.i of the polymer at 340.degree. C.
generated films upon molding and an immediate quench in an ice bath
quickly cooled the sample.
[0133] Dynamic Mechanical Analysis:
[0134] Dynamic mechanical analysis (DMA) utilized an oscillatory
amplitude of 15 .mu.m, a frequency of 1 Hz, and a static force of
0.01 N while in tension mode. The TA Instruments Q800 DMA used a
heating rate of 3.degree. C. min-1 until reaching 300.degree. C.,
and subsequently the sample was rapidly cooled to room temperature
prior to restarting the run. Analysis of the DMA measurement
occurred on the second heat and maximum of the tan delta afforded
the Tg of the polymers.
[0135] Wide-Angle X-Ray Scattering (WAXS):
[0136] These tests were performed using a RIGAKU S-Max 3000 3
pinhole SAXS system, equipped with a rotating anode emitting X-rays
with a wavelength of 0.154 nm (Cu K.alpha.). The sample-to-detector
distance was 110 mm and the q-range was calibrated using a silver
behenate standard. Two-dimensional diffraction patterns were
obtained using an image plate with an exposure time of 1 h. WAXS
data were analyzed using the SAXSGUI software package to obtain
radially integrated WAXS intensity versus the scattering vector,
2.theta., where q=(4.pi./.lamda.)sin(.theta.), .theta. is one half
of the scattering angle and .lamda. is the wavelength of X-ray.
[0137] Polarized Optical Microscopy:
[0138] Polarized optical microscopy (POM) was performed by placing
the samples between crossed polarizers of a NIKON LV100 ECLIPSE
optical microscope equipped with a LINKHAM TMS 94 hot stage and a
NIKON DXM1200 digital camera. Samples were pressed between glass
slides after heating past the T.sub.i and cooled at an approximate
rate of either 10.degree. C. min.sup.-1 or 75.degree. C.
min.sup.-1.
[0139] Melt Rheological Analysis:
[0140] Melt rheology was performed on a TA Instruments DHR-2
rheometer at 340.degree. C. using a 1.25% strain with an 8 mm
disposable parallel-plate geometry under N2 flow. A hole punch
generated circular disks of the sample from a compression molded
film, which were stacked 8 tall on the bottom geometry. The sample
was heated to 340.degree. C. then compressed together by lowering
the top geometry into place. The linear viscoelastic region was
determined prior to each frequency sweep using a strain sweep from
0.01 to 10% oscillatory strain at 1 rad s-1 to guarantee melding of
the films. Frequency sweeps ranging from 1 to 100 rad s.sup.-1
afforded complex viscosity values and standard deviations from a
minimum of three runs.
[0141] Mechanical Analysis:
[0142] The polymer samples were injection molded and the mechanical
properties were tested on the molded bars according to the
following procedure. Samples were injection molded for tensile
testing on a BOY-XS injection molding machine, with mold
temperature of 7.degree. C. (45.degree. F.); barrel temperatures:
275.degree. C.-290.degree. C.; holding pressure: 6.9 MPa (1000
psi); and cycle time: .about.60 sec and were used for measurements
without additional conditioning. Testing was conducted on an
INSTRON 5500R with a crosshead motion rate of 10 mm/min and an
initial grip separation of 25.4.+-.2.0 mm, and on an MTS Model No.
4204 with a 1 kN load cell and a crosshead motion rate of 5 mm/min
(before 5% strain) and 10 mm/min (after 5% strain) with an initial
grip-to-grip separation of 25.4.+-.2.0 mm. Tensile modulus was
estimated by crosshead displacement, but would likely be lower
possibly due to sample slippage, which artificially increased the
measured strain. ASTM D638 requires use of an extensometer in the
initial portion of the test to determine strain. For purposes
herein, an EPSILON 3442 miniature extensometer was employed to more
accurately measure the tensile modulus and related parameters.
Example 1: Synthesis of biphenyl 3,4'-dicarboxylic acid
[0143] Dimethyl 3,4'-bibenzoate was hydrolyzed as seen in Scheme
1:
##STR00001##
[0144] Dimethyl 3,4'-bibenzoate (39.94 g, 0.148 mol) was refluxed
for 24 h in a 1M sodium hydroxide solution (400 mL total) of 1:1
deionized water: THF. The solution was filtered and THF removed
using a rotary evaporator. Biphenyl 3,4'-dicarboxylic acid was
precipitated by the addition of concentrated HCl. A pasty white
precipitate was recovered and washed with distilled water until
neutralized. The product was dried overnight at 120.degree. C. in a
vacuum oven. The chemical structure was confirmed by .sup.1H and
.sup.13C NMR as shown in FIGS. 1A and 1B, respectively.
Example 2: Synthesis of poly(hydroquinone-3,4'-bibenzoate) from
hydroquinone diacetate and biphenyl 3,4'-dicarboxylic acid
[0145] Hydroquinone diacetate (HQa) has the following
structure:
##STR00002##
[0146] HQa was obtained commercially and purified by
recrystallization in a 1:1 mixture of ethanol:distilled water.
Long, finger-like white crystals were filtered from the solution
and dried over night at 100.degree. C. in a vacuum oven. Structure
of the purified product was confirmed by .sup.1H and .sup.13C NMR.
Acidolysis polycondensation of HQa and 3,4'BB afforded liquid
crystalline polyesters without copolymerization, as illustrated in
Scheme 2:
##STR00003##
[0147] Biphenyl 3,4'-dicarboxylic acid (6.237 g, 0.026 mol) and
hydroquinone diacetate (5 g, 0.026 mol) were added to an oven-dried
100 mL round-bottom flask. A mechanical stir rod, distillation
apparatus, and t-neck were attached and the reaction purged three
times with nitrogen and vacuum. The reactor was lowered into a
molten metal bath under constant nitrogen purge, heated to
300.degree. C. with stirring for 0.5 h, then to 330.degree. C. for
0.5 h, then to 360.degree. C. for 0.5 h, and finally vacuum (0.15
mmHg) was applied at 360.degree. C. for 0.5 h. The resulting
polymer was a white product as shown in the line drawing
reproduction of the photograph of FIG. 2A. The product was removed
from the stir rod and used without further purification. The
polymer was compression molded at 340.degree. C. followed by a
quench in an ice bath. The transparent film is seen on the left
side of FIG. 2C, which is a line drawing reproduction of a
photograph of the examples. The compression molded disk of Example
2 is shown partially overlapped with and in front of a compression
molded disk produced from Example 3 below. The transparency
observed in the photograph of the examples is indicated using
gradient stippling. The observed transparency of the polymer
produced in Example 2 is not common with traditional,
fully-aromatic liquid crystalline polyesters. .sup.1H NMR was
performed using a 1:1 mixture d-TFA:CDCl.sub.3 to confirm the final
structure of polymer. The photographs of FIGS. 2A, 2B, and 2C as
originally filed are reproduced in the corresponding priority US
patent application.
Example 3: Synthesis of poly(hydroquinone-3,4'-bibenzoate) from
hydroquinone dipivalate and biphenyl 3,4'-dicarboxylic acid
[0148] Hydroquinone dipivalate (HQp) was synthesized, as
illustrated in Scheme 3:
##STR00004##
[0149] Hydroquinone (5.1 g, 0.046 mol) and pivalic anhydride (20
mL, 0.135 mol) were added to an oven-dried 100 mL round-bottom
flask, and a t-neck, distillation apparatus, and mechanical stir
rod were affixed. The reactor was purged three times with nitrogen
and vacuum to achieve an inert environment. The reaction was held
at 170.degree. C. under a constant nitrogen purge to allow the
reaction to proceed and remove pivalic acid as it was produced.
Monitoring the reaction by thin layer chromatography (TLC), the
reaction was complete after 1 h, and then cooled to room
temperature. The product was filtered and rinsed with ethanol.
Structure and purity were confirmed by .sup.1H NMR.
[0150] Acidolysis polycondensation of HQp and 3,4'BB afforded
liquid crystalline polyesters without copolymerization, as
illustrated in Scheme 4:
##STR00005##
[0151] Biphenyl 3,4'-dicarboxylic acid (6.237 g, 0.026 mol) and
hydroquinone dipivalate (7.167 g, 0.026 mol) were added to an
oven-dried 100 mL round-bottom flask. A mechanical stir rod,
distillation apparatus, and t-neck were attached and the reaction
purged three times with nitrogen and vacuum. The reactor was
lowered into a molten metal bath under constant nitrogen purge,
heated to 300.degree. C. with stirring for 0.5 h, then to
330.degree. C. for 0.5 h, then to 360.degree. C. for 0.5 h, and
finally vacuum (0.15 mmHg) was applied at 360.degree. C. for 0.5 h
to remove any residual pivalic acid and drive the reaction to
completion. The resulting polymer was a tan product as shown FIG.
2B, which is a line drawing reproduction of a photograph of polymer
produced in Example 3. The darker color of the polymer produced in
Example 3, relative to the essentially colorless polymer produced
in Example 2, is indicated in the line drawing by gradient
stippling. The product was removed from the stir rod and used
without further purification. The polymer was compression molded at
340.degree. C. followed by a quench in an ice bath. The transparent
film seen in the right side of FIG. 2C, which is a line drawing
reproduction of a photograph of the examples. The compression
molded disk of Example 3 is shown partially overlapped with and
behind the compression molded disk produced from Example 2 above.
The transparency observed in the photograph of the examples is
indicated using gradient stippling. The observed transparency of
the polymer produced in Example 3 is not common with traditional,
fully-aromatic liquid crystalline polyesters. .sup.1H NMR was
performed using a 1:1 mixture d-TFA:CDCl.sub.3 to confirm the final
structure of polymer, and no difference was observed between the
poly(HQp-3,4'BB) and the poly(HQa-3,4'BB) (Example 2).
[0152] Polarized Optical Microscopy:
[0153] POM was performed on the poly(HQ-3,4'BB) of Examples 2 and 3
at a variety of temperatures tracking the changes in liquid
crystalline textures. The results are shown in FIGS. 3A, 3B, and
3C, which are line drawing reproductions of photographs of the
examples under the indicated conditions. The photographs of FIGS.
3A, 3B, and 3C, as originally filed, are reproduced in the
corresponding priority US patent application. As the figures show,
when quenched from an isotropic state to a temperature of
150.degree. C., which is below the T.sub.g, birefringence was
observed in the sample as indicated in FIG. 3A using gradient
stippling and dashed lines in the line drawing reproduction of a
photograph of the example. After heating to 290.degree. C., which
is above the glass transition temperature, a marbled nematic
texture became more apparent in the example, as indicated in FIG.
3B using gradient stippling and dashed lines in the line drawing
reproduction of a photograph of the example. The birefringence
below the T.sub.g was not associated with a crystalline domain.
When heated to 348.degree. C., which is above the isotropic point,
a loss of anisotropy was observed in the example, resulting in a
black image as indicated in FIG. 3C using gradient stippling in the
line drawing reproduction of a photograph of the example. This
optical behavior is consistent with a polymer that cannot form
crystalline domains, but maintains liquid crystalline ordering,
i.e., a liquid crystalline glass.
[0154] WAXS:
[0155] Performing WAXS on a compression molded film of
poly(HQp-3,4' BB) after different thermal treatments verified the
polarized optical microscopy. Rapidly cooling the initial
compression molded film from the isotropic state (340.degree. C.)
in an ice bath provided a quench-cooled sample for analysis. A
single diffuse scattering peak indicated the absence of a 2D layer
structure that often forms lamellar morphologies prevalent in
smectic mesophases; the data also confirmed the absence of the
packing structure of crystalline domains. The few minor peaks
occurring in the quenched film may have indicated insufficient
quenching of the thick film in comparison to the much thinner
polarized optical microscopy sample. Upon heating the polymer film
for 5 min at 280.degree. C., sharp angular reflections emerged at
5.2, 6.1, 13.1, 14.2, 18.6 19.6, 24.6, and 31.7.degree. 20
indicative of a semi-crystalline morphology forming in the polymer
film corroborating the secondary shoulder observed in the DSC
analysis. These sharp reflections increased slightly in intensity
after longer annealing times (2 h at 280.degree. C.). This limited
crystallinity may have hindered the observation of a textural
change in the optical microscopy after 10 min of annealing.
Attempts to orient the quench-cooled sample below the T.sub.i
(310.degree. C.) resulted in strain induced crystallization rather
than orientation. While the crystallization during orientation
limited the ability to confirm the mesophase morphology for the
polymer, the observation of a schlieren texture using polarized
optical microscopy highly suggests a nematic morphology.
[0156] Thermal Characterization:
[0157] Using TGA, poly(HQ.sub.a-3,4'BB) and poly(HQ.sub.p-3,4'BB)
exhibited a T.sub.d,5% of 484.degree. C. and 487.degree. C.,
respectively. DSC was used with a heat/cool/heat cycle (second
heating) at a heating rate of 10.degree. C./min and cooling rate of
100.degree. C./min to obtain glass transition temperature (T.sub.g)
and isotropic temperature (T.sub.i). As seen from FIG. 4, the
T.sub.g was 198.degree. C. and 184.degree. C. for
poly(HQ.sub.a-3,4'BB) and poly(HQ.sub.p-3,4'BB), respectively,
which could be a result of different molecular weights where
poly(HQ.sub.p-3,4'BB) has lower molecular weight. The T.sub.i was
found to be 332.degree. C. and 324.degree. C. for
poly(HQ.sub.a-3,4'BB) and poly(HQ.sub.p-3,4'BB), respectively.
[0158] Rheological Analysis:
[0159] Frequency sweep studies were used to determine the
zero-shear viscosity of the two polymers of Examples 2 and 3, as
seen in FIG. 5. Poly(HQ.sub.a-3,4'BB) had a zero-shear viscosity of
2510 Pa-s, which was higher than poly(HQ.sub.p-3,4'BB) indicating
the poly(HQ.sub.p-3,4'BB) had a lower molecular weight. As those
skilled in the art will appreciate, the zero-shear viscosity can be
adjusted by aiming for higher or lower molecular weights, e.g., by
utilizing the modified Carothers equation. Using a power law model
fit as seen in FIG. 5A, it is seen that the power law coefficient,
n, was about 0.18 for poly(HQ-3,4'BB). In general, the lower the
power law coefficient the larger the shear thinning. The shear
thinning for poly(HQ-3,4'BB) was similar to VECTRA RD501 liquid
crystalline polymer, with a power law coefficient determined
experimentally to be about 0.11, and greater than that of
polycarbonate, with a power law coefficient value reported in the
literature of about 0.98.
[0160] Dynamic Mechanical Analysis:
[0161] As seen in FIG. 6, the T.sub.g obtained as the tan delta
peak was 205.degree. C. for the polymer of Example 2. Above the
T.sub.g, an increase in the modulus was observed, consistent with
an enhanced mobility of the polymer chains allowing more ordering
to occur, and also with the increase in birefringence seen in the
polarized optical microscopy above the T.sub.g in FIG. 3B. The flow
temperature (T.sub.flow) obtained as the onset of the second
modulus drop was 325.degree. C., which correlates with the
isotropic temperature of this polymer.
[0162] Mechanical Analysis:
[0163] The poly(HQ.sub.p-3,4'BB) of Example 2 was evaluated for
mechanical properties, and the results are presented in Table
1.
TABLE-US-00001 TABLE 1 Mechanical Properties of
poly(HQ.sub.p-3,4'BB) Flexural Modulus (MPa) 4842.35 Flexural
Strength (MPa) 179.28 Tensile Modulus (MPa) 4712.23 Tensile
Strength @ Max Load (MPa) 73.93 Tensile Strain to Failure (%)
1.87
Examples 4-6: Synthesis of
poly(hydroquinone-3,4'-bibenzoate-co-isophthalate)
[0164] The (co)polyesters were prepared from equimolar amounts of
hydroquinone diacetate and biphenyl 3,4'-dicarboxylic acid
generally as described in Example 2 above, in which a portion of
the 3,4'BB was exchanged with either 5, 10, or 20 mole percent of
isophthalic acid (IA). The monomers were added into an oven-dried
100 mL round-bottom flask. A mechanical stir rod, distillation
apparatus, and t-neck were attached and the reaction purged three
times with nitrogen and vacuum. The reactor was lowered into a
molten metal bath under constant nitrogen purge, heated to
300.degree. C. with stirring for 0.5 h, then to 330.degree. C. for
0.5 h, then to 360.degree. C. for 0.5 h, and finally vacuum (0.15
mmHg) was applied at 360.degree. C. for 0.5 h to remove any
residual acetic acid and drive the reaction to completion. The
resulting polymer was removed from the stir rod and used without
further purification.
[0165] The introduction of IA as a secondary kinked monomer
appeared to disrupt the liquid crystallinity of poly(HQ-3,4'BB), as
seen in FIG. 7. As higher amounts of IA are utilized, the T.sub.i
shifts to lower temperatures and the heat of transition
(.DELTA.H.sub.i) decreases in size. As seen in FIG. 8, DMA
correlated with the DSC analysis, and demonstrated a systematic
decrease in the T.sub.flow as IA incorporation increased. The
plateau modulus also exhibited a systematic decrease with
increasing IA content, and the (co)polyester became nearly
amorphous at 20 mol % IA. This trend was further confirmed using
polarized optical microscopy (POM), as seen in FIG. 9, which is a
chart of line drawing reproductions of the POM series arranged by
comonomer content in columns (5, 10, and 20 mol % IA) versus
temperature in rows (below T.sub.g, between T.sub.g and T.sub.i,
and above T.sub.i), in which gradient stippling and dashed lines
are used to indicate the observed birefringence or loss in
birefringence observed. The photographs of FIG. 9 as originally
filed are reproduced in the corresponding priority US patent
application. The incorporation of 5 mol % IA showed a clearly
marbled nematic texture. As more IA was incorporated into the
(co)polyester, a decrease in the observed birefringence occurred,
indicating the liquid crystallinity had been disrupted. FIG. 10
shows the rheological frequency sweep curves for the
poly(HQ.sub.a-IA-3,4'BB) (co)polyester series.
Examples 7-9: Synthesis of
poly(hydroquinone-3,4'-bibenzoate-co-terephthalate)
[0166] The (co)polyesters were prepared from equimolar amounts of
hydroquinone diacetate and biphenyl 3,4'-dicarboxylic acid
generally as described in Example 2 above, in which a portion of
the 3,4'BB was exchanged with either 5, 10, or 20 mole percent of
terephthalic acid (TA). The monomers were added into an oven-dried
100 mL round-bottom flask. A mechanical stir rod, distillation
apparatus, and t-neck were attached and the reaction purged three
times with nitrogen and vacuum. The reactor was lowered into a
molten metal bath under constant nitrogen purge, heated to
300.degree. C. with stirring for 0.5 h, then to 330.degree. C. for
0.5 h, then to 360.degree. C. for 0.5 h, and finally vacuum (0.15
mmHg) was applied at 360.degree. C. for 0.5 h to remove any
residual acetic acid and drive the reaction to completion. The
resulting polymer was removed from the stir rod and used without
further purification.
[0167] Incorporation of TA into poly(HQ-3,4'BB) had a varied effect
in comparison to IA, as seen in FIG. 11. Initial incorporation of
TA at 5 and 10 mol % caused a slight decrease in T.sub.i which
could be explained by an initial disruption of the packing and
linearity. As higher levels of TA were added, a significant jump in
the T.sub.i to a temperature above the limit of the DSC was seen,
apparently due to an increase in the polymer linearity, e.g.,
poly(HQ-TA) is known to be a very crystalline polymer that cannot
be processed due to its high degree of linearity and order. POM was
utilized to determine the T.sub.i for the (co)polyester with 20 mol
% TA by watching for the melt to become black at 370.degree. C., as
seen in FIG. 12, which is a chart of line drawing reproductions of
the POM series arranged by comonomer content in columns (5, 10, and
20 mol % TA) versus temperature in rows (below T.sub.g, between
T.sub.g and T.sub.i, and above T.sub.i), in which gradient
stippling and dashed lines are used to indicate the observed
birefringence or loss in birefringence observed. The photographs of
FIG. 12 as originally filed are reproduced in the corresponding
priority US patent application. All (co)polymers exhibited marbled
nematic textures, and did not exhibit any crystalline textures.
Further, the DMA analysis followed closely to the observed thermal
trends of DSC, as seen in FIG. 13. A decrease in T.sub.flow
appeared to correlate with the decrease in T.sub.i of (co)polymers
with 5 and 10 mol % TA, along with a drop in the plateau modulus.
At 80 mol % TA incorporation, the copolymer appeared to have a
further decrease in the plateau modulus and T.sub.flow well below
T.sub.i. FIG. 14 shows the rheological frequency sweep curves for
the poly(HQ.sub.a-TA-3,4'BB) (co)polyester series.
Examples 10-12: Synthesis of
poly(hydroquinone-3,4'-bibenzoate-co-naphthalene dicarboxylate)
[0168] The (co)polyesters were prepared from equimolar amounts of
hydroquinone diacetate and biphenyl 3,4'-dicarboxylic acid
generally as described in Example 2 above, in which a portion of
the 3,4'BB was exchanged with either 5, 10, or 20 mole percent of
naphthalene dicarboxylic acid (NDA). The monomers were added into
an oven-dried 100 mL round-bottom flask. A mechanical stir rod,
distillation apparatus, and t-neck were attached and the reaction
purged three times with nitrogen and vacuum. The reactor was
lowered into a molten metal bath under constant nitrogen purge,
heated to 300.degree. C. with stirring for 0.5 h, then to
330.degree. C. for 0.5 h, then to 360.degree. C. for 0.5 h, and
finally vacuum (0.15 mmHg) was applied at 360.degree. C. for 0.5 h
to remove any residual acetic acid and drive the reaction to
completion. The resulting polymer was removed from the stir rod and
used without further purification.
[0169] The fused ring of NDA appeared to have a more disruptive
effect on the (co)polyester linearity at low mol % incorporation
than TA, as seen in FIG. 15. At 5 mol %, no T.sub.i was observed in
the second heat of the DSC scan, although at 10 mol % a T.sub.i
began to reemerge as the linearity of the polymer apparently
increased. At 20 mol % incorporation the NDA pushed the T.sub.i to
a temperature greater than the limit of the DSC, and instead the
T.sub.i was observed through optical microscopy. FIG. 16 is a chart
of line drawing reproductions of the POM series arranged by
comonomer content in columns (5, 10, and 20 mol % NDA) versus
temperature in rows (below T.sub.g, between T.sub.g and T.sub.i,
and above T.sub.i), in which gradient stippling and dashed lines
are used to indicate the observed birefringence or loss in
birefringence observed As seen in FIG. 16, POM demonstrated a
marbled nematic texture and the inhibition of a crystalline
texture. The photographs of FIG. 16 as originally filed are
reproduced in the corresponding priority US patent application. The
observation of limited birefringence below the T.sub.g at 5 mol %
NDA confirmed the limited liquid crystallinity of this (co)polymer
observed by DSC. The DMA analysis shown in FIG. 17 demonstrated a
systematic drop in plateau modulus and T.sub.flow as the mol % NDA
was increased. This was unexpected for 10 and 20 mol % NDA, since
the results for IA and TA previously seen in Examples 4-9 suggested
higher levels of order and thus less of a decrease in T.sub.flow.
This may indicate that, as linearity of the polymer is increased,
the nematic mesophase is aligning more and enabling higher mobility
between chains allowing for flow in the nematic state. FIG. 18
shows the rheological frequency sweep curves for the
poly(HQ.sub.a-NDA-3,4'BB) (co)polyester series.
Example 13: Synthesis of
poly(hydroquinone-3,4'-bibenzoate-co-4,4'-bibenzoate)
[0170] The (co)polyester was prepared from equimolar amounts of
hydroquinone diacetate and biphenyl 3,4'-dicarboxylic acid
generally as described in Example 2 above, in which 10 mole percent
of the 3,4'BB was exchanged with 10 mole percent of biphenyl
4,4'-dicarboxylic acid (4,4'BB). The monomers were added into an
oven-dried 100 mL round-bottom flask. A mechanical stir rod,
distillation apparatus, and t-neck were attached and the reaction
purged three times with nitrogen and vacuum. The reactor was
lowered into a molten metal bath under constant nitrogen purge,
heated to 300.degree. C. with stirring for 0.5 h, then to
330.degree. C. for 0.5 h, then to 360.degree. C. for 0.5 h, and
finally vacuum (0.15 mmHg) was applied at 360.degree. C. for 0.5 h.
The resulting polymer was removed from the stir rod and used
without further purification. The DSC seen in FIG. 19 demonstrated
a much smaller decrease in T.sub.i for the 4,4'BB comonomer
relative to the other diacid comonomers of Examples 3-12.
[0171] Selected properties of the polyesters of Examples 2-3 and
the (co)polyesters of Examples 4-13 are summarized in Table 2.
TABLE-US-00002 TABLE 2 Properties of 3,4'BB-HQ and its
(co)polyesters .DELTA.H.sub.f T.sub.i.sup.1 .DELTA.H.sub.i T.sub.g,
.degree. C. (.DELTA.C.sub.p), (T.sub.m), (.DELTA.H.sub.m),
T.sub.g,.degree. C. T.sub.flow, .eta.*, Ex. Polyester (DSC) W/g
.degree. C. J/g (DMA) .degree. C. Pa s 2 3,4'-BB-HQa 198 (0.05) 332
26.7 203 315 251824 (320) 3 3,4'-BB-HQp 184 (0.05) 324 20.4 65423
(315) 4 95-3,4'BB- 187 0.0944 317 20.5 199 304 2920 5-IA-HQ 5
90-3,4'BB- 187 0.114 305 16.34 206 293 11115 10-IA-HQ 6 80-3,4'BB-
198 0.107 N/A N/A 211 290 40070 20-IA-HQ 7 95-3,4'BB- 189 0.0277
321 16.1 198 298 7990 5-TA-HQ 8 90-3,4'BB- 175 0.0604 319 16.1 196
293 7079 10-TA-HQ 9 80-3,4'BB- 179 0.0833 370* N/A 194 291 10142
20-TA-HQ 10 95-3,4'BB- 199 0.0578 N/A N/A 205 307 3331 5-NDA-HQ 11
90-3,4'BB- 179 0.0850 312 9.55 209 286 20968 10-NDA-HQ 12
80-3,4'BB- 167 0.0430 >400 NA 181 269 3035 20-NDA-HQ.sup.1 (300)
(3.40) 13 90-3,4'BB-10- 188 0.0484 326 12.9 211 308 N/A 4,4'BB-HQ
.sup.1T.sub.i determined by optical microscopy
[0172] Although only a few example embodiments have been described
in detail above, those skilled in the art will readily appreciate
that many modifications are possible in the example embodiments
without materially departing from this invention. Accordingly, all
such modifications are intended to be included within the scope of
this invention as defined in the following claims. It is the
express intention of the applicant not to invoke 35 U.S.C. .sctn.
112(f) for any limitations of any of the claims herein, except for
those in which the claim expressly uses the words `means for`
together with an associated function and without any recitation of
structure. The priority document is incorporated herein by
reference.
* * * * *