New glass fibre reinforced polyether TPUs - Plasticker

glass fi bre reinforced tpu
Tough and fl exible even at low temperatures
New glass fi bre reinforced
polyether TPUs
J. Hättig, J. Winkler, P. Kläne*
High stiffness, very good impact resistance and flexibility even at low temperatures –
these are the strengths of new glass fibre reinforced polyetherdiol based thermoplastic
polyurethanes (TPUs). Bayer MaterialScience AG and geba Kunststoffcompounds GmbH
developed the new TPU materials and they complement the recently introduced glass
fibre reinforced polyester TPUs of the same product family.
Demand for glass fibre reinforced TPU
grades has increased noticeably in recent
years. They are increasingly in demand, for
example in mechanical engineering, automotive
and sports industries, security technology,
tools, at household appliance manufacturers
and producers of offshore technical equipment.
The range of applications for glass fi bre
reinforced TPU has therefore become highly
differentiated. The to some extent very different
and specifi c technical performance requirements
set by the various customer industries
cannot therefore be covered with just a
few universal types of material.
Bayer MaterialScience and geba Kunststoffcompounds
have taken this trend as
an opportunity to jointly develop a range
of reinforced and additive modifi ed TPUs.
The trade name of these compounds is Desmovit
R (R = reinforced). They are all based
on Desmopan, a TPU from Bayer Material-
Science. The company has given geba a
trade name license to produce reinforced
* Jürgen Hättig
Jürgen Winkler
TPUemea@bayer.com
Business Development TPU resins,
Europe, Middle East, Africa and Latin America
(EMEA/LA) region, Polyurethanes Business Unit,
Bayer MaterialScience AG, Dormagen, Germany
Peter Kläne
Marketing Manager,
geba Kunststoff compounds GmbH,
Ennigerloh, Germany
compounds from the TPU, and market them
under the Desmovit R brand name. Their
nomenclature is similar to that of TPU products
from Bayer MaterialScience, only that
the two numbers at the end of the product
code identify not the hardness, but the
fl exible modulus at room temperature, as
a much more important property for reinforced
products.
Impact strength at –30 °C higher
than at room temperature
The latest representatives of the product
family are Desmovit DP R 9918, 9920,
9924, 9929 and 9930. These polyether TPUs
have glass fi bre content of 20 wt.-% and
cover a wide fl exural modulus range from
1,800 MPa to 3,000 MPa (at room temperature).
They complement glass fibre reinforced
polyester TPUs that are already sold
in the market, which have fl exural modulus
values of 1,400 MPa to 3,200 MPa. The
Fig. 1:
With their very good cold
impact strengths, the
new ether TPUs are very
suitable for production
of ski tips. The parts are
produced by Arwö-Plast,
Neumarkt, Wallersee,
Austria. (Source: Völkl,
Fisher)
new ether TPUs are wear resistant, yet also
very fl exible. A particular strength is very
good impact strength at low temperatures
for grades with fl exural modulus in
the range of 1,800 MPa to 3,000 MPa. Cold
impact strengths at –30 °C are comparable
to those at room temperature and in some
cases even better (tab. 1).
For example, Desmovit DP R 9929 has
Charpy impact strength (ISO 179/1eU) of
75 kJ/m 2 at room temperature and 82 kJ/m 2
at –30 °C. Test bars in Desmovit DP R 9918,
9920 and 9924 withstand this test at –30 °C
without even breaking.
Low stiffening factors
The increase in stiffness of the new materials
when exposed to cold temperatures
is relatively moderate. Individual stiffening
factors, which are shown by the ratio
of fl exural modulus values at –30 and
at +23 °C, are therefore relatively low and
lie between 1.5 and 1.8. The mechanical
properties profi le of the materials therefore
varies to only to a small extent over
a wide temperature range and remains
to a large extent both constant and usable,
right down to low temperatures. This
opens up a wide application window for
the polyether TPUs. Low stiffening factors
additionally result in high rebound
elasticity, which is one of the reasons for
the high shock resistance of the materials.
These still show elastic behaviour at temperatures
below –30 °C. In contrast, their
ester-based “siblings” are rigid and brittle
at –30 °C (tab. 2).
100 TPE Magazine · 2|2012

Thermal expansion comparable
with metals
The new TPUs exhibit good UV stability,
alongside high heat distortion temperatures.
Some values of over 126 °C have been obtained
in heat distortion temperature (HDT)
testing according to DIN EN ISO 75/1-3,
Method A, at 1.8 Mpa load, as well as 174 °C
under Method B at 0.45 MPa load (tab. 1).
Thermal expansion is signifi cantly lower than
for many other plastics and approaches that
of metals. Coeffi cients of thermal expansion
are comparable with those of aluminium. It
is therefore easier with the new ether TPUs
to design narrow gaps between adjacent
parts of assembled components (zero-gap
appearance). This is important in automotive
engineering or in high-end equipment
with demanding design features.
As the new TPUs are based on materials
such as polyetherdiols, they are more resistant
against microbes and decomposition
through hydrolysis compared with their
polyester based “siblings”. This also applies
for permanent contact with seawater. Their
fl ow capability and precision in reproduction
of surface structures are both at a high
level. They may be easily painted and printed.
Compared with other plastics, they dampen
noise very effectively. Relatively low density
of 1.3 g/cm 3 facilitates economic production
of components through low weight of the
material consumed.
High load bearing
The polyether TPUs have potential for
applications involving mainly components
exposed to high mechanical load and that
also have to perform well at low temperatures.
This applies, e. g. for functional parts
of sports articles such as ski tips (fi g. 1),
covers, binders, goggles and edge protectors,
functional parts in ski shoes, technical
functional parts, as well as housings for
Tab. 1: Properties of Desmovit R glass fi bre reinforced polyether TPU (n. b. = no breakage) (Source: geba)
agricultural and building construction machinery.
There are also large opportunities
in riding and motor sport protection, safety
helmets, as well as housings and switches
for household appliances and electric tools.
The high seawater resistance, cold impact
strength and shock resistance predestine the
new TPUs equally well for use in ship equipment
and in the fi shing industry – such as
for fi shing net weights.
Their application in the offshore area is
especially attractive. They lend themselves
for example as housing materials for geophysical
measurement probes. Such components
sometimes spend more than a year
in seawater – often in polar regions – and
may not fail, on account of the enormous
costs for repair and replacement. With wear
resistance, fl exibility and seawater resistance,
the new TPUs are suitable in addition
as material for production of zips for
divers’ suits. On account of noise-dampening
properties, they are also an interesting
Properties Test conditions Unit Standard DP R 9918 DP R 9920 DP R 9924 DP R 9929 DP R 9930
Mechanical properties
Tear resistance 200 mm/min MPa ISO 527 59 59 67 71 73
Elongation at break 200 mm/min % ISO 527 17 14.5 10 8 6
Flexural modulus 1 mm/min 23 °C MPa ISO 178 1,800 2,000 2,400 2,900 3,000
Flexural modulus 1 mm/min –30 °C MPa ISO 178 3,000 3,500 3,900 4,300 4,600
Bending strength 2 mm/min 23 °C MPa ISO 178 54 60 68 78 87.2
Bending strength 2 mm/min –30 °C MPa ISO 178 118 131 142 154 161
Charpy impact strength 23 °C kJ/m2 ISO 179/1eU n. b. n. b. n. b. 75 60
Charpy impact strength –30 °C kJ/m2 ISO 179/1eU n. b. n. b. n. b. 82 70
Charpy notched impact strength 23 °C kJ/m2 ISO 179/1eA 45 40 33 26 18
Charpy notched impact strength –30 °C KJ/m2 ISO 179/1eA 22 20 15 14 8.5
Shore hardness
Thermal properties
Shore D ISO 868 D 64 67 68 68 71
Heat distortion temperature, method A 1.8 MPa ISO 75/1-3 126 119 126 122 121
Heat distortion temperature, method B 0.45 MPa ISO 75/1-3 167 156 172 161 174
Vicat softening temperature
Other properties
50 N, 50 °C/h ISO 306 B 92 94 105 104 115
Density g/cm3 ISO 1183-1-A 1.29 1.3 1.31 1.32 1.31
Abrasion mm3 ISO 4649 80 78 82 83 102
Linear expansion coeffi cient longitudinal ppm/K DIN 53752-A 10.3 10.3 7.2 9.6 13.7
Linear expansion coeffi cient transverse ppm/K DIN 53752-A 114 114 120 117 123
Shrinkage after conditioning longitudinal % 0.1 0.12 0.12 0.13 0.2
Shrinkage after conditioning
Processing guidelines
transverse % 0.32 0.51 0.36 0.38 0.58
Injection moulding melt temperature °C 200 – 230
Injection moulding tool temperature °C 40 – 80
Drying temperature (dry air drier) °C 120 – 130 (2 h residual moisture < 0.03 %)
TPE Magazine · 2|2012 101

glass fi bre reinforced tpu
material alternative in production of noiseabsorbing
elements for vehicle bodies or of
noise-dampening components in automotive
engineering, such as parts for heating
and ventilation systems.
Glass fi bre reinforcement of
ether TPU
The relatively limited offer in the market
of ether TPU with glass fi bre reinforcement
has a reason. TPU is sensitive to the
high temperatures that arise as a matter of
course due to high shear as the glass fi bres
are compounded into the TPU. Bayer MaterialScience
and geba therefore had to build
up broad process technology know-how as
part of their co-operation in development of
Desmovit R. Here, geba ran various trials with
different types of glass fi bres while varying,
e. g. the processing parameters, screw geometries
and screw confi guration. The result is
a process that allows relatively gentle but
yet effective compounding of special glass
fi bres, even though high temperatures are
involved. The know-how created also fl owed
into optimisation of the already commercialised
polyester TPUs.
Outlook
Desmovit R is a range of products that
should become continually extended. Beyond
the presently available material grades, stiffer
or softer material grades with higher or
lower glass fi bre contents can be compounded,
according to customer requirements. The
prerequisite is that the amounts to be supplied
are economic to produce. In addition,
geba offers glass bead fi lled material versions.
They are the material of choice if components
have to be especially dimensionally
stable with low shrinkage. Reinforcement of
ether TPU with carbon fi bres is possible for
components with increased strength combined
with low weight.
Tab. 2: Properties of Desmovit R glass fi bre reinforced polyester TPU (n. b. = no breakage) (Source: geba)
In the medium term, the co-operation
partners plan to extend the product range
not only with long glass fibre reinforced
grades, but also with bio-based polyether
and polyester TPUs that should then be reinforced
with natural fi bres. This development
is an answer to the large trend towards
conservation of resources and thereby also
to sustainable materials.
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Properties Test conditions Unit Standard 3914 3918 3922 3926 3932
Mechanical properties
Tear resistance 200 mm/min MPa ISO 527 58 64 67 76 83
Elongation at break 200 mm/min % ISO 527 23.4 22 18.1 14.6 11.4
Flexural modulus 1 mm/min 23 °C MPa ISO 178 1,365 1,785 2,160 2,610 3,195
Flexural modulus 1 mm/min –30 °C MPa ISO 178 3,620 4,690 5,350 5,860 6,220
Bending strength 2 mm/min 23 °C MPa ISO 178 43 56 66 81 99
Bending strength 2 mm/min –30 °C MPa ISO 178 129 163 191 209 227
Charpy impact strength 23 °C kJ/m2 ISO 179/1eU n. b. 142 117 104 92
Charpy impact strength –30°C kJ/m2 ISO 179/1eU 100 91 86 75 60
Charpy notched impact strength 23 °C kJ/m2 ISO 179/1eA 70 60 52 40 24
Charpy notched impact strength –30 °C KJ/m2 ISO 179/1eA 20 14 11 10 9
Shore hardness
Thermal properties
Shore D ISO 868 D 62 67 70 72 72
Heat distortion temperature, method A 1.8 MPa ISO 75/1-3 130 127 127 130 130
Heat distortion temperature, method B 0.45 MPa ISO 75/1-3 162 155 157 162 159
Vicat softening temperature
Other properties
50 N, 50 °C/h ISO 306 B 125 125 131 139 146
Density g/cm3 ISO 1183-1-A 1.36 1.36 1.35 1.36 1.38
Abrasion mm3 ISO 4649 65 64 64 58 61
Linear expansion coeffi cient longitudinal ppm/K DIN 53752-A 9 7 11 16 21
Linear expansion coeffi cient transverse ppm/K DIN 53752-A 139 131 140 130 131
Shrinkage after conditioning longitudinal % 0.36 0.49 0.45 0.49 0.58
Shrinkage after conditioning
Processing guidelines
transverse % 0.11 0.11 0.14 0.12 0.16
Injection moulding melt temperature °C 220 – 245
Injection moulding tool temperature °C 40 – 80
Drying temperature (dry air drier) °C 120 (4 h residual moisture < 0.03 %)
102 TPE Magazine · 2|2012