WHOLLY AROMATIC POLYETHER ESTERS AND THE PREPARATION THEREOF

ESTERS DE POLYESTERS ENTIEREMENT AROMATIQUES ET PROCEDE DE PREPARATION

English Abstract

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Abstract of the Disclosure: Wholly aromatic polyether
esters which form a liquid-crystalline fiber-forming melt
at below 300°C are composed of
a) not less than 10 mol % of repeat units of the for-
mula I
<IMG> I
b) a molar amount equivalent to the total amount of
components c) and d) of repeat units of the formula II
<IMG> II
c) from 5 to 20 mol % of repeat units of the formula
III
<IMG> III
and
d) from 10 to 30 mol % of repeat units of the formula
IV
<IMG> IV
the molar proportions of components a, b, c and d adding
up to 100 mol % in each case,
the preparation thereof, andfibers, films, moldings and
surface coating materials prepared therefrom.

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:
1. A wholly aromatic polyether ester which forms
a liquid-crystalline fiber-forming melt below 300°C and is
composed of:
a) not less than 10 mol % of repeat units of the formula
(I):
<IMG> (I)
b) a molar amount equivalent to the total amount of
components c) and d) of repeat units of the formula (II):
<IMG>
(II)
c) from 5 to 20 mol % of repeat units of the formula (III):
<IMG> (III)
and
d) from 10 to 30 mol % of repeat units of the formula (IV):
-8-

<IMG>
(IV)
the molar proportions of components a), b), c) and d) adding
up to 100 mol %.
2. A wholly aromatic mesomorphic polyether ester
as claimed in claim 1, which contains from 10 to 15 mol % of
component c) and from 15 to 25 mol % of component d).
3. A wholly aromatic mesomorphic polyether ester
as claimed in claim 1, which further contains one or more
repeat units selected from the group consisting of:
e) repeat units of the formula (V):
<IMG> (V)
f) repeat units of the formula (VI):
(VI)
<IMG>
and
g) repeat units of the formula (VII):
-9-

<IMG> (VII)
where R is methyl, phenyl or chlorine, and n is 1, 2 or 3,
the molar proportion of components d), e), f) and g) adding
up to 10 to 30 mol %.
4. A wholly aromatic mesomorphic polyether ester
as claimed in claim 3, wherein the molar proportions of the
components of the formulae (V), (VI) or (V) and (VI) are
from 5 to 10 mol %.
5. A wholly aromatic mesomorphic polyether ester
as claimed in claim 3 or 4, wherein the molar proportion of
component (VII) is from 5 to 20 mol %.
6. A wholly aromatic mesomorphic polyether ester
as claimed in claim 1, 2 or 3, which has a glass transition
temperature Tg of ? 150°C.
7. A process for preparing polyether esters as
claimed in claim 1 comprising reacting the monomers in a
single stage in the form of underivatized hydroxy and
carboxy compounds in the molar ratios recited in claiml in
the presence of excess fatty acid anhydride at elevated
temperatures ranging from 150 to 350°C, and distilling fatty
acid anhydride and fatty acid out of the reaction mixture.
8. A process as claimed in claim 7, where.in the
wholly aromatic polyether ester is postcondensed in the
solid phase at 150-250°C.
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9. A fiber prepared from a wholly aromatic
polyether ester as claimed in claim 1, 2 ou 3.
10. A film prepared from a wholly aromatic
polyether ester as claimed in claim 1, 2 or 3.
11. A molding prepared from a wholly aromatic
polyether ester as claimed in claim 1, 2 or 3.
12. A surface coating material as prepared from a
wholly aromatic polyether ester as claimed in claim 1, 2
or 3.
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Description

` ~26~3a~3~
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Wholly aromatic polyether esters and the
preparation thereof
The present invention relates to wholly aromatic
polyether esters which form a liquid-crystalline fiber-
forming melt below 300C.
Wholly aromatic liquid-crystall;ne polyesters ~re
known. However, these polyesters lack adequate heat dis-
tortion resistance, and the surface quality thereof, in
particular the abrasion resistance, is also unsatisfactory.
EP Application 115,967 describes add;ng from 10 to 70%
by volume of wollastonite to aromatic polyesters which
are based on hydroxynaphthalenecarboxylic acid, tereph-
thalic acid and aromatic dihydroxy compounds, to improve
the abrasion resistance. However, the addition of such
fillers impairs other properties of the polymer. EP App-
lication ~1,900 proposes 4,4 -d;(p-hydroxyphenoxy)diphenyl
sulfone as a possibLe starting material for the prePara-
tion of anisotropic polyester amides and polyesters, but
provides no indication as to the surface quality of the
products obtained or the heat distortion resistance thereof.
lt is an object of the present invention to pro-
vide wholly aromatic liquid-crystalline polyether esters
which form a liquid-crystalline fiber-forming melt below
300C and thus are easy to process and which also have a
very high glass transition temperature, a high abrasion
resistance and a high chemical resistance.
~e have found that this object is achieved with
wholly aromatic polyether esters which form a liquid-
crystalline fiber-forming melt below 300C and are cc,mposed
of
a) not less than 10 mol % of repeat units of the for-
mula I
r~ !l
~ ' I
b) a molar amount equivalent to the ~otal amoun~ of
components c) and d) of repeat units of the formula II

12~
. ~
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c) from 5 to 20 mol % of repeat units of the formula
III
-o ~ o ~ 502 ~ o- III
and
d) from 10 to 30 mol % of repeat units of the formula
IV
CH~
H3C-C-CH3
~ IV
the molar proportions of components a, b, c and d adding
1û up to 1~0 mol % in each case.
The novel wholly aromatic liquid-crystalline poly-
ether esters have the advantage of not requiring high pro-
cessing temperatures and, what is more, of having excel-
lent sustained use properties even at elevated tempera-
tures. They also have high abrasion resistance and chemi-
cal resistance.
The liquid-crystalline state of the polyether es
ters can be detected with a polarization microscope by a
method described in German Published Application DAS
Z0 2,520,810. Applied in a thickness of 10 ~m between glass
plates and viewed between crossed polarizers, the polymer
melts have ~extures which can be ascribed to a mesomorphic
~nematic) phase.
The polyether esters accurding to the invention
are composed of
a) not less than 10 mol % of repeat units of the
formula I
o
~_ I

88~
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a possible starting material being, for exampLe, p-hydroxy-
benzoic acid,
b) a molar amount corresponding to the total amount
of c) and d) of repeat units of the formula II
~ f
C ~ C- II
a preferred starting compound being terephthalic acid,
c) from 5 to 20 mol % of repeat units of the formula
III
--O~ O ~ SO2 ~ o ~ o-- III
a starting compound being, for example, 4,4'-di(p-hydroxy-
phenoxy)diphenyl sulfone and
d) from 10 to 30 mol % of repeat units of the formula
IV
ICH3
H~C-C-CH3
I V
an advantageous starting compound being tert-butylhydro-
quinone.
Preferred wholly aromatic polyether esters contain
in addition to component a) from 10 to 15 mol % of com-
ponent c), from 15 to 25 mol % of component d) and a molar
Z0 amount equivalent to the total amount of c) and d) of com-
ponent b).
In other preferred wholly aromatic polyether
esters, some of units d) are replaced by
e) repeat units of the formula V
~0 V
a starting compound being~ for example, hydroquinone, and/
or
f) repeat units of the formula VI

~,88~
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- ~ YI
a suitable starting compound being, preferably, 4,4'-dihy-
droxybiphenyl, and/or
g) repeat units of the formula VII
_ ~ o-
~l~n VII
where R is methyl, phenyl or chlorine and n is 1, 2 or 3.
Suitable starting compounds are methylhydroquinone, tri-
methylhydroquinone, phenylhydroquinone and chlorohydro-
quinone.
Advantageously these wholly aromatic polyether
esters contain repeat units e) and/or f3 in an a~ount of
from 5 to 10 mol %. In another preferred composition,
the wholly aromatic polyether esters contain component g)
in an amount from 5 to 20 mol %.
It ~ill be readily understood that the propor-
tions of components a, b, c and d add up to 100 mol % in
each case.
Preferred wholly aromat;c li~uid-crystalline poly-
ether esters have a glass transition temperature of > 150C,
in particular > 160C. This glass transition temperature
is measured by the DSC method described by K. H~ Illers
et al. in Makromol. Chem. 127 (1969), 1. Preference is
given to li~uid-crystalline polyether esters which have
partial crystallinity at > 220C and < 280C. The poly~
ether esters according to the invention form a liquicl-
crystalline fiber-forming melt at < 300C.
The liquid-crystalline polyether esters according
to the invention can be prepared by various methods, for
example as described in US Patents 4,375,530 and 4,118,372.
The mass condensation generally includes an alka-
noylating stage, where the monomers used are reacted with
anhydridesr and a polymerization stage, in which the

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O~Z. 0050/38135
polycondensate is formed by elimination of aliphatic carb-
oxylic acids. Processes which include a prepolymeriza-
tion stage are described in German Laid-Open Application
DOS 3,320,118. However, these processes require reaction
times of more than 10 hours.
In an advantageous embodiment, the polyesters ac-
cording to the invention are obtained in a single-stage
process by converting the underivatized starting materials
us;ng anhydrides of lower fatty acids, for example fatty
acids of 2 to 4 carbon atoms, in particular acetic anhyd-
ride~ Advantageously this reaction is catalyzed with
known catalysts for polycondensation and transesterifica-
tion reactions, used in an amount of from 0.001 to 1% by
weight, based on the starting materials. The starting
materials are heated together with, for example, acetic
anhydride, which is advantageously present in a molar ex-
cess of not less than 5%, based on the hydroxyl groups
present, with stirring, preferably under an inert gas, to
a temperature at which reflux occurs. Advantageously the
temperature is increased in stages, for example to 150-
220C in not more than 5 hours, preferably up to 2 hours,
and the temperature is then slowly raised to 250-350C,
while excess fatty ac;d anhydride and fatty acid are dis-
tilled off. To remove the last residues of fatty acid, it
is expedient to employ recluced pressure, ~or example do~n
to 0.5 mbar, to~ard the end of the condensation.
It is a remarkable and unforeseeable feature of
this single-stage process that the desired poLymers are
obtained in a relatively short time in a troublefree and
complete reaction even without catalysts. This is all the
more astonishing as the large number of chemically diff-
erent hydroxyl groups would be expected tv lead to differ-
ences in reactivity and hence to inadequate polymer synthe-
s i s .
The wholly aromatic liquid-crystalline polyether
esters thus obtained are advantageously further condensed
in the solid state, for example at 150 250C~ until the

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desired viscosity is obtained. This solid phase condensa-
tion can take place not only be~ore but also after thermo-
plastic forming. The wholly aromatic liquid-crystalline
polyether esters according to the invention are suitable
for preparing filaments, films, foams and industrial mold-
ings by injection molding or extruding.
The invention is illustrated by the following
Examples.
EXAMPLE 1
0.2 mol (30.3 mol %) of terephthalic acid, 0.26
mol (39.4 mol %) of 4-hydroxybenzoic ac;d, 0.16 mol (24.24
mol %) of t-butylhydroquinone, 0.04 mol ~.06 mol X) of
4,4'-di(p-hydroxyphenoxy)diphenyl sulfone and 0.86 mol of
acetic anhydride are weighed into a flask equipped with
stirrer, nitrogen inlet and distillation attachment.
Under nitrogen the contents are then heated in a metal
bath to 100C. The temperature is then raised to 150C
in 30', to 200C ;n a further 100' and finally to 325C in
120'.
The pressure is then reduced to 560 mbar and sub-
sequently halved every 10'. The final vacuum is 10 mbar.
In this way a highly viscous fiber-forming mesomorphic
melt is obtain~d. DSC measurements indicate a glass tran-
sition temperature of 156C. The intrinsic viscosity is
25 0.9 dl/g, measured at 50C in an 0.5% strength by weight
solution in p-chlorophenol.
The polymer can be processed from the melt at T
> Tg, in particular at T 2 200C.
EXAMPLE 2
0.2 mol (30.3 mol %) of terephthalic acid~ 0.26 mol
(39.4 mol X) of 4-hydroxybenzoic acid, 0.12 mol (18.2 mol %)
of t-butylhydroquinone, 0.08 mol (12.1 mol X) of 4,4'-di(p-
hydroxyphenoxy)phenyl sulfone and 0.86 mol of acetic anhy-
dride are reacted as in Example 1. DSC measurements indi-
cate a glass transition temperature of 166C~ The intrin-
sic viscosity is 0.5 dl/g. The polymer can be processed
from the melt at T > Tg, in particular at T 2 200C.

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7 O.~. 0050/38135
EXAMPLE 3
0.2 mol (27.03 mol %) of terephthalic acid, 0.34
mol (45.94 mol %) of 4-hydroxybenzoic acid, 0.16 mol
(21.62 mol %) of t-butylhydroquinone, 0.04 mol (5.41 mol
~) of 4,4'-di(p-hydroxyphenoxy)diphenyl sulfone and 0.86
mol of acetic anhydride are reacted as in Example 1. DSC
measurements indicate a glass transition temperature of
165C. The intrinsic viscosity is 0.93 dl/g. The poly-
mer can be processed from the melt at T > Tg, in particu-
lar at T 2 200C.