JEC COMPOSITES MAGAZINE - Issue #79 - March 2013 - 108

resins

Thermosets for sustainable production
of automotive composite components
Polymer composite materials can help to substantially reduce the
weight and hence the CO2 emissions of future automobiles. Epoxy
resins, the preferred matrix choice for structural composites in
today’s aerospace and wind turbine industries, were once believed not to be a viable solution for automotive mass markets due
to long processing times. However, recent advances in epoxy
matrix technology have made significant strides toward low-cost
production of composite components.

he latest EPIKOTETM/EPIKURETM liquid moulding resin systems
can be processed in a matter of
seconds using manufacturing technologies
such as compression moulding or RTM.
These new matrices can be processed isothermally in two minutes or less and, unlike
other composite matrices, are non-toxic and
VOC-free, making them viable solutions for
a wide range of future applications.

less. At such speeds, the time used for filling
the mould and completely impregnating
the reinforcing fibres becomes a challenge.
Structural composite parts require relatively
high fibre volumes of 50% or more. Such
parts are difficult to fill, particularly when
carbon fibre is used. Very low viscosity and
sufficient impregnation time are the two key
requirements for achieving quality finished
parts. For instance, the ideal impregnation
viscosity of a RTM resin should be below
200 mPa·s for the duration of the impregnation/mould-filling step. Depending on

Dr roMAn hillerMeier, technology DevelopMent
leADer tAnsportAtion
Dr. tAreq hAsson, r&D MAnAger
coMposites, frAncis Defoor, globAl
MArket segMent leADer trAnsportAtion
MoMentive speciAlty cheMicAls, inc.

part size and geometry, this may take up to
one minute. Liquid compression moulding
resins require slightly different characteristics, as the impregnation regimes are
somewhat less demanding.
Figure 2 shows the viscosity curves of two
different, newly developed fast-curing liquid
moulding resin systems. System A (EPIKOTE resin 05475 and EPIKURE curing
agent 05443) cures fully within 5 minutes
at 120°C. System B (EPIKOTE resin 05475
and EPIKURE curing agent 05500) cures

Development of epoxy matrices
for high-volume liquid moulding
processes
The cure time required to crosslink epoxy
resins has been one of the key bottlenecks
in higher volume composite production.
Hence, much attention has been focused
on so-called “fast cure” systems in recent
years.1,2 Figure 1 shows the recent trend
in automotive industry cure cycle time
improvements.
While high-end premium or super sport car
manufacturers use aerospace industry-derived processes that necessitate cure cycles
of hours, high-volume automotive manufacturing requires cure cycles of minutes or

Fig. 1: Cure times of current generation automotive epoxy composite resins

108 jec composites magazine / No79 March 2013

JEC COMPOSITES MAGAZINE - Issue #79 - March 2013

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