Homogeneous polymer alloys based on sulfonated aromatic polyether ketones

Homogeneous polymer alloys based on sulfonated, aromatic polyether ketones Homogeneous polymer alloys comprising sulfonated, aromatic polyether ketones and at least one polyamide as the main constituents, wherein the polyamide is a completely aromatic polyamide.

The invention relates to polymer alloys which comprise sulfonated, aromatic 
polyether ketones and at least one completely aromatic polyamide as the 
main constituents in a homogeneous mixture, a process for the preparation 
of the alloys and their use. 
The principle of modification of the properties of polymer materials by 
preparation of homogeneous polymer alloys is known. In this way, 
technologically important properties of polymer materials can be improved 
or adjusted in a controlled manner, these properties often being 
realizable only with difficulty, if at all, in another manner, such as, 
for example, by copolymerization. 
A fundamental prerequisite for the possibility of preparation of a 
homogeneous polymer alloy is the complete miscibility of the alloy 
components. However, complete miscibility is an unusual property in 
polymer systems, which normally tend to form multiphase systems (Polymer, 
volume 24, page 60 (1983)). 
Even modern thermodynamic theories have had only limited success to date 
regarding prediction of miscibility. It has therefore been doubted that 
any practical theory can be developed which takes into account the real 
complexities imparted to polymer-polymer interactions by nature 
(Macromolecules, Volume 16, page 753 (1983)). 
The ability to predict with certainty the properties of an alloy from the 
properties of its individual components is therefore as yet still a long 
way off, so that alloying of polymers is still largely empirical (Olabisi, 
Robeson, Shaw: Polymer-Polymer-Miscibility, Academic Press, New York 1979, 
pages 321-327). In particular, the homogeneous miscibility of polymer 
alloys which comprise highly interactive polymers cannot be predicted, in 
spite of a very large number of experimental and theoretical studies in 
this field (Journal of Polymer Science, Polymer Physics Edition, volume 
21, page 11 (1983)). 
In industry, however, there is very great interest in homogeneous mixed 
polymer alloys, since their properties can be adjusted in a controlled 
manner to suit particular requirements by varying the alloy components and 
their mixing ratios. 
Sulfonated polyether ketones are already known. They can be prepared by 
conventional sulfonation processes (for example in accordance with 
EP-A-008895 and EP-A-041780), but are also accessible by a novel process 
(German Patent Application P 4 219 077.0). They are distinguished in 
particular by a high heat resistance, an excellent hydrophilicity and by a 
good solubility in organic solvents, such as N-methylpyrrolidone or 
N,N-dimethylformamide. 
Sulfonated polyether ketones have already been alloyed with partly 
aliphatic polyamides (EP-A-0 337 626). However, the lack of chemical 
stability of these alloys, especially toward polar organic solvents, is a 
disadvantage in particular in respect of applications where hydrophilic 
properties of materials coupled with stability to solvents are required. 
Thus, for example, fibers are required to achieve a certain water 
absorption capacity in order to guarantee good wearing comfort of fabrics. 
In respect of their use for "fouling-resistant" semipermeable membranes, 
i.e. semipermeable membranes with a low tendency to block, the materials 
employed must also display adequate hydrophilicity. 
Furthermore, it is necessary for the mechanical properties of a polymer 
alloy to be adapted to suit the particular desired field of use. 
This invention was therefore based on the object of providing homogeneous 
polymer alloys based on sulfonated polyether ketones and polyamides, the 
water absorption capacity of which and the mechanical properties of which 
can be adjusted in a controlled manner by varying the components of the 
mixture and/or the mixing ratios. Furthermore, the novel systems should be 
resistant to chemicals and heat. 
This object is achieved by providing homogeneous polymer alloys which 
comprise sulfonated, aromatic polyether ketones and at least one polyamide 
as the main constituents and in which the polyamide is a completely 
aromatic polyamide. A completely aromatic polyamide is derived formally 
from an aromatic dicarboxylic acid and an aromatic diamine. In addition to 
the sulfonated, aromatic polyether ketone and completely aromatic 
polyamide, the homogeneous polymer alloy according to the invention can 
also contain other polymers to a lesser extent. The alloys according to 
the invention are preferably free from partly aliphatic polyamides 
according to EP-A-337 626. 
According to one embodiment of the invention, the polymer alloy comprises 
at least one sulfonated, aromatic polyether ketone and at least one 
completely aromatic polyamide. 
In addition to the sulfonated, aromatic polyether ketone and the completely 
aromatic polyamide, even smaller amounts of poly-N-vinyl-2-pyrrolidone can 
also be present--according to one embodiment of the invention. The polymer 
alloy can also comprise a copolymer which is built up from the monomers 
N-vinyl-2-pyrrolidone and vinyl acetate, in addition to the 
poly-N-vinyl-2-pyrrolidone. According to another embodiment of the 
invention, a copolymer of N-vinyl-2-pyrrolidone and vinyl acetate (but no 
poly-N-vinyl-2-pyrrolidone) is present in the polymer alloy, in addition 
to the sulfonated, aromatic polyether ketone and the completely aromatic 
polyamide. 
If the polymer alloy comprises a sulfonated, aromatic polyether ketone and 
a completely aromatic polyamide, each of the two constituents is present 
in an amount of 1 to 99% by weight. 
If the polymer alloy also comprises poly-N-vinyl-2-pyrrolidone and/or a 
copolymer of N-vinyl-2-pyrrolidone and vinyl acetate, it is advantageous 
if the content of sulfonated, aromatic polyether ketone is 5 to 60% by 
weight and the content of completely aromatic polyamide is 20 to 90% by 
weight. The content of polyvinylpyrrolidone and/or a copolymer of 
N-vinyl-2-pyrrolidone and vinyl acetate is preferably 0.1 to 30% by 
weight. 
It is advantageous if the sulfonated, aromatic polyether ketones are built 
up from recurring units of the formula I 
##STR1## 
in which Ar is a phenylene ring with para and/or meta bonds, 
Ar'--is a phenylene, naphthylene, biphenylene or anthrylene unit or another 
divalent aromatic unit, 
X, M and N independently of one another are zero or 1, 
Y is zero, 1, 2 or 3 and 
p is 1, 2, 3 or 4, 
and in which, in the formula I, 20 to 100% of the O-phenylene-O units are 
substituted by an SO.sub.3 H group. Preferably, in the formula I, the 
indices p, X and M are coordinated with one another such that 
p=2-(1-X).multidot.M. 
Sulfonated polyether ketones which are preferably employed are those of the 
formula II 
##STR2## 
in which a is a number from 0.2 to 1, c is a number from 0 to 0.8 and the 
sum of a+c=1, of the formula III 
##STR3## 
in which a is a number from 0.2 to 1, c is a number from 0 to 0.8 and the 
sum of a+c=1, and of the formula IV 
##STR4## 
in which a is a number from 0 to 1, b is a number from 0 to 1, c is a 
number from 0 to 0.5 and the sum of a+b+c=1. 
Sulfonated polyether ketones which are composed of at least two different 
recurring units of the formulae II, III and IV furthermore can also be 
employed. 
They can be prepared by copolymerization of units of the formulae II, III 
and IV (but which are free from sulfonic acid groups) and subsequent 
sulfonation of the copolymer obtained. 
The sulfonated polyether ketones employed preferably have molecular 
weights, stated as the weight-average, in the range from 10,000 to 60,000 
g/mol, in particular in the range from 20,000 to 30,000 g/mol. 
The sulfonated polyether ketones can be prepared by a customary sulfonation 
process (for example EP-A0-008 895 and EP-A0-041 780). Sulfonation is 
preferably carried out by the process described in German Patent 
Application P 4 219 077.0, which is expressly referred to here. 
The polymer alloys according to the invention comprise, as the completely 
aromatic copolyamide, preferably at least one copolyamide which contains 
structural units of the formula (V) 
EQU --HN--Ar.sup.2 --Z.sup.1 --Ar.sup.3 --(--Z.sup.2 --Ar.sup.3 --Z.sup.3 
--Ar.sup.2 --).sub.n --NH--OC--Ar.sup.1 --CO-- (V) 
in which 
--Ar.sup.1 -- is a 1,4-phenylene radical or another divalent (C.sub.6 
-C.sub.12)-aromatic or heteroaromatic radical optionally containing 
sulfonic acid groups or ether bridges, which is optionally substituted by 
one or two branched or unbranched C.sub.1 -C.sub.4 -alkyl or alkoxy 
radicals or by one or more halogen atoms, for example chlorine, fluorine 
or bromine, 
--Ar.sup.2 -- and --Ar.sup.3 -- are identical or different 1,2-phenylene, 
1,3-phenylene or 1,4-phenylene radicals, which are optionally substituted 
by one or two branched or unbranched C.sub.1 -C.sub.4 -alkyl or alkoxy 
radicals or by one or more halogen atoms, for example chlorine, fluorine 
or bromine, 
--Z.sup.1, --Z.sup.2 -- and --Z.sup.3 -- independently of one another are a 
direct bond or one of the following divalent radicals: --O--, 
--C--(CH.sub.3).sub.2 --, --C(CF.sub.3).sub.2 --, --SO.sub.2 -- or 
--O--Ar.sup.2 --O--, in which --Ar.sup.2 -- has the abovementioned 
meaning, and 
n is an integer, in particular n=0, 1 or 2. 
Preferred copolyamides are those of the formula V which contain the 
structural unit 
EQU --OC--Ar.sup.2 --CO--, (A) 
and three different structural units of the formulae 
EQU --NH--Ar.sup.2 --NH-- (B) 
and 
EQU --HN--Ar.sup.2 --Z.sup.1 --Ar.sup.3 --(--Z.sup.2 --Ar.sup.3 --Z.sup.3 
--Ar.sup.2 --).sub.n --NH-- (D) 
wherein in each case at least one structural unit B and D should be present 
and Ar.sup.2 can have different meanings in B and D. 
Preferably, n=0 here. 
Examples of the unit --Ar.sup.1 -- in the recurring units A are 
##STR5## 
in particular 
##STR6## 
Examples of --Ar.sup.2 -- in the recurring units B are substituted or 
unsubstituted p-phenylene units, such as, for example, 
##STR7## 
and substituted or unsubstituted m-phenylene units, such as, for example, 
##STR8## 
Examples of Ar.sup.2 --Z.sup.1 --Ar.sup.3 in the recurring units D are 
##STR9## 
in particular 
##STR10## 
The following are particularly preferred: 
##STR11## 
Preferably, in the completely aromatic copolyamide, the structural units A, 
B and D are present in the molar ratios of B/A=0.3-0.9 and D/A=0.1-0.7, 
and the molar ratio of (B+D)/A is 0.9 to 1.1. 
The diamines B', B", D' and D" which are necessary for the structural units 
(B) and (D) and are employed in the synthesis of the completely aromatic 
copolyaramides having the structural units A, B and D are usually employed 
in the following concentrations: 
Diamine (B'): 0 to 50 mol % 
Second diamine (B"): 0 to 60 mol % 
Diamines (D', D"): 10 to 70 mol % (per diamine unit (D') or (D")) 
based on 100 mol % of the acid component (A') employed, the molar ratio of 
diamine components to acid components being 0.90:1.10 to 1.10:0.90, 
preferably 1:1. 
The copolyamides mentioned here can be prepared by solution condensation of 
the aromatic di-acid chlorides with the mixtures of the aromatic diamines, 
analogously to the processes described in the European Patents EP-A-0 199 
090, EP-A-0 322 837 and EP-A-0 445 673 and in the German Patent 
Applications P 41 04 394, P 41 21 801 and P 42 02 16 5.0, in aprotic, 
polar solvents of the amide type, such as, for example, in 
N,N-dimethylacetamide or, in particular, in N-methyl-2-pyrrolidone. If 
appropriate, halide salts of the first and second group of the Periodic 
Table can be added to these solvents in a known manner in order to 
increase the dissolving capacity and to stabilize the polyamide solutions. 
Preferred additions are calcium chloride and/or lithium chloride. 
The intrinsic viscosity, which is a measure of the average chain length of 
the polymers formed, of the copolyamides used as alloy components is 
preferably between 50 and 1000 cm.sup.3 /g, preferably between 100 and 500 
cm.sup.3 /g, especially preferably between 150 and 350 cm.sup.3 /g. It was 
determined on solutions of in each case 0.5 g of polymer in 100 ml of 96% 
strength sulfuric acid at 25.degree. C. 
The molecular weights of the polyvinylpyrrolidone (=PVP) and of the 
copolyvinylpyrrolidone/polyvinyl acetate (abbreviated to: CoPVPAc), the 
other possible components of the homogeneous polymer alloys according to 
the invention, are, stated as the weight-average, usually 1000 to 3 
million, preferably 20,000 to 200,000, in particular 40,000 to 100,000. 
The homogeneously miscible polymer alloys according to the invention can be 
prepared from a common solution which comprises at least one sulfonated, 
aromatic polyether ketone and polyvinylpyrrolidone and/or CoPVPAc or which 
comprises at least one sulfonated, aromatic polyether ketone and at least 
one polyaramide or at least one sulfonated polyether ketone, at least one 
polyaramide and polyvinylpyrrolidone and/or CoPVPAc, in an aprotic organic 
solvent, for example dimethylformamide, dimethylsulfoxide, 
N-methylpyrrolidone or N,N-dimethylacetamide. For this, for example, the 
polyaramide can be subjected to polycondensation in the corresponding 
solvent, the sulfonated polyether ketone (and if appropriate 
polyvinylpyrrolidone and/or CoPVPAc) can be dissolved in a suitable 
concentration and a mixture of the particular polymer solutions in the 
calculated ratio of amounts can then be prepared. 
If appropriate, halide salts of the first and second group of the Periodic 
Table can be added to these solvents in a known manner in order to 
increase the solubility and to stabilize the polyamide solutions. 
Alternatively, sulfonated polyether ketone (and if appropriate 
polyvinylpyrrolidone and/or CoPVPAc) can be added directly in the dry form 
to the polyaramide solution when the polycondensation has ended. 
For preparation of the ternary alloy, polycondensation of the polyaramide 
in the presence of polyvinylpyrrolidone or CoPVPAc and subsequent addition 
of sulfonated polyether ketone in solution or in the dry form is 
preferred. 
Polycondensation of the polyaramide in the presence of polyvinylpyrrolidone 
and CoPVPAc and subsequent addition of the sulfonated polyether ketone in 
solution or in the dry form is preferred in respect of the preparation of 
the quaternary alloy. 
A process in which the polycondensation for the preparation of the 
polyaramide is carried out in the presence of the sulfonated polyether 
ketone and, if appropriate, in the presence of polyvinylpyrrolidone and/or 
CoPVPAc is particularly preferred. 
The polymer alloys according to the invention can be isolated from the 
solutions by removal of the solvent, for example by evaporation, and 
further processed to intermediate products (granules or powder), which can 
then be employed as raw materials for the production of shaped articles, 
films, fibers or coatings. 
Advantageous properties of the homogeneously miscible polymer alloys 
according to the invention which are based on sulfonated polyether ketones 
and completely aromatic polyaramides are their mechanical properties, 
which are improved, for example compared with sulfonated polyether 
ketones, and the improved elongation at break is particularly advantageous 
(Table 2). Moreover, the hydrophilicity of the alloys can be adjusted in a 
controlled manner by admixing polyvinylpyrrolidone or CoPVPAc (Table 3). 
The invention is illustrated in more detail by the following examples.