Note: Descriptions are shown in the official language in which they were submitted.
1 ~ 23443 428
HULS ARTIENGESELLSCHAFT O.Z- 4437
- PATENTABT~ILUNG -
Proceqs for the preparation of a thermoDlastically
processible aromatlc polyamide
~he invention relates to a process for the preparation of
a thermoplastically proceqsible aromatic polyamide by
polycondensation of the following starting monomers~
. HOOC - Ar - COOH
B. H2N - Ar' - NH2
in which the ~y~bol~ have the meaning~ which follow
Ar: 1,3- or 1,4-Phenylene; 1,4-, 1,5-, 2,6- or
2,7-naphthylene,
~ Zn
or
~Y~X~ ~
Ar':
~Y~X~Y~
X: -52-; -CO-;
y: -0-; -S-;
Z: -0-; -S-; -S02-; -C0-; -CR2-;
R: -H Cl - C4-Alkyl;
n: 0; 1;
in the melt in the pre~ence of a catslyst at temperatures
in the range of from 200 to 400-C.
The preparation of polyamides of this type is known in prin-
ciple(German Published Patent Application No. 3,609,011). How-
ever, the melt viscosity of these aromatic polyamides is high.
Very high temperatures are therefore necessary in their
preparation and processing - generally at least 350C. At these
- 2 ~ i o.z. 4437
temperatures, damage to the product is often observed,
recognizable from discolorations or a deterioration in
the mechanical properties.
A further disadvantage of the polyamides which have been
prepared in this manner is their sen~itivity to
hydrolytic degradation, resulting from a hiqh water
absorption. To prevent this, other measures are necessary
during processing, for example dryinq.
The object of the invention is to provide moulding
compositions based on aromatic polyamides, which do not
have the described disadvantage~ of the prior art
products.
This ob~ect is achieved by using the component A. in a
molar excess relative to the component B..
The mole ratio of component A.: component B. i~ prefer-
ably in the range of from 1.1 to 1.01:1.0 and in par-
ticular 1.08 to 1.02:1Ø
Suitable aromatic dicarboxylic acids (component A.) are
isophthalic acid, terephthalic acid, 1,4-, 1,5-, 2,6-,
and 2,7-naphthalenedicarboxylic acid, 4,4~-diphenyl ether
dicarboxylic acid or 4,4~-benzophenonedicarboxylic acid,
4,4'-diphenyl sulphone dicarboxylic acid, 2-phenoxy-
terephthalic acid, 4,4'-biphenyldicarboxylic acid or
mixtures thereof.
Preference i8 given to the use of isophthalic acid alone
or a mixture of isophthalic acid and one of the other
abovementioned acids, as component A.. Ultimately up to
45 mol % of isophthalic acid is replaced.
Examples of suitable aromatic diamines (component B.) are
4,4'-bis(4-amino-phenoxy)diphenyl sulphone, 4,4'-bis(3-
aminophenoxy)diphenylsulphone~4r4~-bist4-aminophenoxy)
benzophenone,4,4'-bis(3-aminophenoxy)benzophenone~4~4~-
~ i 23443-428
- 3 - O.Z. 4437
bis(p-aminophenylmercapto)benzophenon0, 4,4'-b$s~p-amino-
phenylmercapto)diphenyl ~ulphone or mixture~ thereof.
Preference i8 given to the u~e of 4,4'-bi3(4-amino-
phenoxy)diphenyl sulphone.
The glass tran~ition temperature (T,) of the polyamides
according to the invention i8 in the range of from 190 to
270-C and the visco~ity number~ (J value3) are
approximately 30 to 100 cm3~g; preferably 6 to 80 cm3/q.
The preparation of the aromatic polyamides is known in
principle. I~ i~ desc~ibsd in, amon~ other source~,
German Published Patent Application No. 3,609,011.
The polycondensation i~ carried out in the pre~ence of
catalysts. Suitable catalyst~ for this purpose are
pho~phorus-containlng compounds ~uch as triphenyl
phosphite or acids of the general formula H3P0~ in which
m - 2 to 4. It ie also pos~ible to u~e, mixed with these
substances, tin~II) compounda such a~, for example,
tin(II) ~alts of organic carboxylic acida.
It is al~o known to addition~lly u~e co-catalysts such
as, for ex~mple, dialkylam$nopyridine~.
~he catalysts are used in amount~ ~rom 0.05 to 4 mol ~,
preferably 0.1 to 2 mol %, relAtive to the 8um of the
components A. and B
~he reaction i8 carried out ~n the melt at temperatures
in the range of from 200 to 400-C, preferably from 230 to
360-C.
It i8 normal to operate at atmo~pheric pressure under an
inert ga~. However, it io ~180 poa~ible to employ
elevated pre~ure or reduced pre~sure.
The molecular weight can be increased by sub~ecting the
- 4 - ~ .Z. 4437
aromatic polyamides ~o solid phase post-conden~ation in
an inert gas atmosphere.
The polyamides can be processed on conventional machines
by in~ection moulding or extrusion to give moulding
compositions.
The moulding compositions may additionally contain
fillers such as talc or reinforcing agents ~uch as glas~
fibres, ARAMIDR fibres or carbon fibres and also other
customary additives such as, for example, pigments or
~tabilizers.
The moulding compositions are processed by conventional
processes such as in~ection moulding, extrusion and the
liXe to give moulding~, fibres, films and 50 on. Equally,
it is possible to use the said moulding compositions as
coating compositions starting from powder (for example
fluidized bed coating), from a liquid dispersion or from
a solution.
Aromatic polyamides which have been prepared by the
process according to the invention withstand unexpectedly
high temperature~. The products can be processed at
temperatures even in excess of 340C without diminution
of the molecular weight or brown discoloration occurring.
Furthermore, moulding compositions obtained according to
the invention have an excellent resistance to thermo-
oxidation so that they can be used at significantlyhigher temperatures than the corresponding prior art
composi~ions. These properties include good heat
resi~tance, i.e. moulding compositions which are based on
aromatic polyamides according to the invention can be
exposed to high temperatures for long period-~ without a
significant loss of mechanical properties. Furthermore,
the said compositions have an unexpectedly high
hydrolysis resistance.
The quantities mentioned in the description and in the
- 5 ~ O.Z. 4437
examples were determined using the processes which are
given below.
The glass transition temperature (T~) was determined by
DSC using a heating rate of 10C/min.
The viscosity numbers (J) were determined from 0.5 %
strength by weight solutions of the polyamide~ in a
phenol/o-dichlorobenzene mixture (1:1 by weight) at 25C
in accordance with DIN 53 728.
The heat ageing of the test pieces was carried out at
250C in a circulating-air oven with a fresh air supply
of 10 %.
The examples designated by letters are not according to
the invention.
Examples
_xam~le 1:
21.62 g (O.OS mol) of 4,4'-bis(4-aminophenoxy)diphenyl
sulphone and 8.64 g (0.052 mol) of isophthalic acid were
melted with 155 mg (0.0005 mol) of triphenyl phosphite
and 61.1 mg (0.005 mol) of 4-dimethylaminopyridine in a
polycondensation reactor fitted with a stirrer, nitrogen
feed and distillation arm at 250C. After 20 minute~, the
temperature was increased to 300C. At the same time the
viscosity of the melt increased steadily while the water
liberated in the course of the reaction was distilled
off. After 10 minutes at 300C, the reaction was
terminated.
The viscosity number (J) was 24 cm3/g. Solid phase post-
condensation at 250C and 0.5 mbar gave, after 24 h, a
polyamide having J = 68 cm3/g .
- 6 ~ 3~ ~ 0.2. 4437
ExamDles 2 - 6 and Exam~les A and B
The Examples 2 - 6 and also Examples A and B were poly-
condensed similarly to Example 1, but the excess of
dicarboxylic acid and the catalyst components were varied
S in accordance with the following table.
Heat aaeina
The polyamides prepared in Examples 1 to 6 and also in A
and B were press-moulded at 310C and a pressure of
lO0 bar to sheetY of 1 mm thickness and aged for 2 hours
in an circulating-air oven. The polyamides prepared in
Examples A and B were dark brown in colour while the
polyamides prepared according to Examples 1 to 6 showed
virtually no discoloration.
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