Exolit® for

Unsaturated polyester resins
(UP resins)
Lightweight constructions
with Exolit
Fiberglass reinforced composites play an important part in construction,
transportation, tanks, pipes and electrical components.
These composites can be manufactured by Sheet Moulding
Compound (SMC)/Bulk Moulding Compound (BMC), Resin
Transfer Moulding (RTM) processing or open mold techniques.
Unsaturated polyester resins are important for those applications.
Very often these composites have to fulfill stringent fire and
safety regulations, necessitating the use of flame retardants.
To meet these requirements, the use of halogenated UP resins
(frequently combined with antimony trioxide as synergist) and
aluminium trihydroxide (ATH, flame retardant filler) has become
standard practice in recent years. But ATH in particular is likely
to bring an increase in viscosity (owing to higher filler levels to
reach the required fire retardation) and higher densities of the
components. Moreover, halogenated flame retardants have come
under public and legislative pressure because of widespread findings
in the environment, toxic effects and the potential formation
of halogenated dioxins by uncontrolled combustion [ lit.: Beard A.,
Angeler D. (2010): Flame Retardants: Chemistry, Applications,
and Environmental Impacts. Wiley-VCH, Weinheim. Wiley-VCH.
pp. 415-439. ]
The Exolit grades offer major advantages especially in construction
and rolling stock applications. By combining the Exolit products
with aluminium trihydroxide stringent flammability requirements
can be met even with low filler levels. In addition, Exolit grades can
be used to formulate intumescent (gel)-coats which drastically
improve the fire endurance of the whole composite part. Clariant
is a world wide leader in the manufacturing of ammonium polyphosphate,
one of the key raw materials for the formulation of
intumescent (gel)-coatings.
In addition to the traditional hand lay-up process, the Exolit
flame retardants can be used in pultrusion and other advanced
techniques.
Advantages of systems with Exolit:
· Low density of the components
· Low processing viscosity
· High glass contents are possible
· Halogen free hand lay-up formulations are possible
· Pultrusion and advanced composite techniques possible
· Low smoke density, no corrosive combustion gases
Figure 1: Formulation examples with Exolit AP 740 and AP 422
for different flame tests
250
Picture 1:
Intumescent gel-coating
after flammability test
200
FR content [phr]
150
100
50
0
BS 476 NF P 92 501 EN 45545 DIN 5510
part 2
UL 94
n Exolit AP 750 n Exolit AP 422 n ATH
6
Exolit for Thermosets