Note: Descriptions are shown in the official language in which they were submitted.
21~~~~~
GAF-HULS Chemie C~nbH 0 . Z . 4 8 3 8
Polyester shaped articles having an excellent heat
stability
The invention relates to shaped articles having an
excellent heat stability based on high molecular weight
polyesters which contain olefinic double bonds.
Shaped articles based on the polyesters mentioned are
known from EP-A-0 559 072. However, the long-chain
compounds primarily employed therein are very expens-
ive, and moreover are accessible only with extreme
difficulty. Although an increase in the heat distortion
temperature is achieved under the process parameters
described as essential, this is not sufficient to with-
stand brief exposure to heat, such as occurs during
various soldering processes in electrical engineering
(bath soldering, reflow soldering), without visible
damage or deformation. In this technology, components
are usually exposed to temperatures of 200 to 400°C for
a period of 3 to 60 seconds.
According to the prior art, thermoplastics which have a
high heat stability, such as, for example, poly-
phenylene sulphide (PPS), polyether-imide (PEI) or
polyether-ether-ketone (PEEK), are used, inter alia,
for this purpose. However, on the one hand the high
processing temperatures of 300 to 400°C and on the
other hand the high price prove to be disadvantageous
here.
The object of the present invention was accordingly to
render possible shaped articles from polyester moulding
compositions which are easy and inexpensive to produce
and furthermore withstand the brief exposure to heat
during the soldering processes customary in electrical
engineering without damage.
This object is achieved according to the invention in
that the shaped articles are based on polyesters which
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are built up from units which are derived from the
following monomers:
A. organic dicarboxylic acid and.
B. a. 0 to 99.9 mol ~ of an alkanediol or cyclo-
alkanediol having 2 to 12 C atoms in the
carbon chain and
b. 0.1 to 100 mol $ of an alkenediol having 4
to 12 C atoms in the carbon chain
and in that, after shaping, they have been subjected to
a treatment with ionizing radiation, the irradiated
dose being in the range above 200 to not more than
2,000 kGy in cases where component B comprises more
than 2.5 mol $ of alkenediol and the irradiated dose
being in the range above 400 to not more than 2,000 kGy
in cases where component B comprises 0.1 to 2.5 mol $
of alkenediol.
The polyesters are prepared by esterification or trans-
esterification and subsequent polycondensation of
organic dicarboxylic acids or polyester-forming deriva-
tives thereof and the corresponding diol mixture in the
presence of catalysts (Sorenson and Campbell, Prepara-
tive Methods of Polymer Chemistry, Interscience Pub-
lishers Inc., (N.Y.), 1961, pages 111 to 127; Kunst-
stoff-Handbuch (Plastics Handbook), Volume VIII, C.
Hanser Verlag Munich, 1973; J. Polym. Sci., Part A 1,
4, pages 1851 to 1859, 1966).
The reaction temperatures here are in the range from
160 to 350°C, preferably in the range from 170 to
280°C. The reaction mentioned is carried out with sub-
stantial exclusion of oxygen. For this reason, the
esterification or transesterification is preferably
carried out in an inert gas atmosphere. Suitable inert
gases are, for example, noble gases, nitrogen, carbon
dioxide and the like. The polycondensation stage is
2~.~~~4a
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preferably carried out in vacuo.
(Cyclo)aliphatic and preferably aromatic acids, if
appropriate also as a mixture, are employed as the
organic dicarboxylic acid. They have 2 to 36, preferab-
ly 4 to 18 C atoms in the carbon skeleton.
Examples which may be mentioned of {cyclo)aliphatic
acids are 1,4-cyclohexanedicarboxylic acid, adipic
acid, sebacic acid, azelaic acid, decanedicarboxylic
acid and dimeric fatty acids; possible aromatic acids
are chiefly phthalic acid, isophthalic acid, naphtha-
lenedicarboxylic acid and, in particular, terephthalic
acid. The acids can in each case be employed individ-
ually or also as a mixture. Instead of the free acids,
derivatives thereof, such as, for example, esters, in
particular methyl esters, can advantageously be
employed.
The diol component B. a. is formed by alkanediols or
cycloalkanediols having 2 to 12 C atoms in the carbon
chain. Examples which are suitable here are ethylene
glycol, butane-1,4-diol, hexane-1,6-diol, 1,4- and 1,3-
dimethylolcyclohexane or neopentylglycol. It is of
course also possible for mixtures of different diols to
be employed here.
Compounds which are preferably used as the alkenediol
{component B. b.) are those having 4 to 6 C atoms in
the carbon chain, such as, for example, 2-butene-1,4-
diol, 3-hexene-1,6-diol, 2-pentene-1,5-diol or 3-
methyl-2-pentene-1,5-diol. 2-Butene-1,4-diol is parti-
cularly preferably employed.
The alkenediol is preferably employed in amounts of 1
to 40 mol ~.
The term polyester also includes block copolyesters.
Such products are described, for example, in Chimia 28
2~.~~4D
- 4 - O.Z. 4838
(9), pages 544 to 552 (1974) and in Rubber Chemistry
and Technology 50, pages 688 to 703 (1977). In addition
to the abovementioned aromatic dicarboxylic acids and
diols, these block copolyesters comprise a
poly(oxyalkylene)diol having a molecular weight in the
range from about 600 to 2,500. Preferred poly(oxyalkyl-
ene)diols are poly(oxyethylene)diol,
poly(oxypropylene)diol and poly(oxytetramethylene)diol.
The content of poly(oxyalkylene)diols is in the range
from 4 to 40$ by weight, preferably 10 to 35$ by weight
(based on the total block copolyester).
When the polycondensation has ended, the polyesters
usually have a viscosity number in the range from 50 to
200 cm3/g, preferably 70 to 180 cm3/g.
The moulding compositions employed for preparation of
the shaped articles according to the invention can also
comprise auxiliaries and additives. Possible substances
for this purpose are, for example, nucleating, matting
and flow agents or other processing auxiliaries, as
well as pigments, fillers and reinforcing substances,
flameproofing agents and impact modifiers.
The moulding compositions can comprise nucleating,
matting and flow agents and other processing auxili-
aries in amounts of up to 6~ by weight, preferably 0.2
to 3.5~ by weight.
The moulding compositions comprise pigments, fillers
and reinforcing substances, flameproofing agents and
impact modifiers in amounts of up to 60~ by weight,
preferably 1 to 50$ by weight.
The shaped articles according to the invention can be
produced on the customary machines, for example by
injection moulding or extrusion.
Shaped articles according to the invention include not
214~aQ
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only mouldings having a pronounced three-dimensiona l
structure, but also films, foils, fibres and the like.
After the shaping, the resulting shaped articles are
subjected to a treatment with ionizing rays. Commer-
cially available sources of ~- or y-rays, for example,
are employed for this operation. Thus, electron beam
accelerators having an output of 150 kV to 5 MV can be
used as a source of ~-rays, and, for example, Co6° and
Cs'3' preparations with high radiation output can be
used as sources of y-rays.
The dose required for the irradiated ionizing radiation
is above 200 to not more than 2,000 kGy, and in par-
ticular in the range from 300 to 1,000 kGy.
The process according to the invention is distinguished
by the following advantages:
- the irradiated shaped articles can be exposed to very
high temperatures in the short term, for example in a
flow soldering bath at 250 to 260°C or even higher;
- the shaped articles according to the invention can be
produced by the processing processes customary for
thermoplastics, such as injection moulding or extru-
sion;
- the mechanical properties, such as tensile strength,,
impact strength and the like, are influenced posi- -
tively by the irradiation.
Shaped articles which have been produced by the process
according to the invention are particularly suitable
for fields of use where a high resistance to heat in
the short term is required, for example for electrical
components which are resistant to soldering baths, such
as, for example, plug-in connectors, relays,
resistances, capacitors, semiconductor components, and
2~~8~4~
._ - 6 - O.Z. 4838
as films for printed circuits. Profiles, pipes, sheath-
ings and hollow bodies can likewise be produced.
The invention is to be illustrated by way of example
below. The experiments identified with letters are not
according to the invention.
Examyles
Preparation of the polyester moulding compositions
The composition of the polyester moulding compositions
according to the invention is shown in Table 1. The
polyesters were prepared by known processes by trans-
esterification and subsequent polycondensation of
dimethyl terephthalate with the diol mixture mentioned
using iso-propyl titanate as the catalyst.
Production of the test specimens
To determine the mechanical properties and the resis-
tance to soldering baths, tensile bars S3 according to
DIN 53455 and flat bars (80 x 10 x 4 mm) were produced
by the injection moulding process at processing tem-
peratures of 240 to 260°C and mould temperatures of 60
to 80°C. The test specimens were then exposed to ~3-
radiation with the radiation doses shown in Table 1.
Determination of the use properties
The tensile test to determine yield stress, elongation
and tear strength was carried out on irradiated test
specimens (test bar S3) in accordance with DIN 53455.
The impact strength was determined in accordance with
ISO 180 lU. Testing of the resistance to soldering
baths was carried out in a liquid metal bath (Wood's
alloy) at 250°C and 260°C. For this, the test specimens
were in each case immersed completely in the metal bath
for 10 seconds and then evaluated visually.
~14~~4~
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Comparison Examples (identified with letters)
Because of the inaccessibility of the diol component
10-eicosene-1,20-diol (no CAS No.) described in EP-A-
0 559 072, the comparison experiments were carried out
with 2-butene-1,4-diol and irradiated in accordance
with the radiation dose of 100 kGy stated therein.
After immersion in the liquid metal bath at 250°C, the
test specimens showed clearly visible deformations.
Furthermore, the surface was superficially fused.
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Table 1 Composition
Example Diol component in mol ~ Radiation intensity
B1D* B2D** in kGy
A 99 1 100
1 99 1 600
B 95 5 100
2 95 5 250
3 95 5 400
4 95 5 600
C 75 25 100
5 75 25 250
6 75 25 400
7 75 25 600
8 75 25 1,000
*B1D = 1,4-butanediol
**B2D = 2-butene-1,4-diol
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