Plastics News - Show Daily - October 15, 2024 - 5

FAKUMA 2024
Plastics News, October 15, 2024 * 5
LSR, PEEK, TPU already benefi t from a potential PFAS ban
By David Vink
Plastics News Correspondent
A European Chemical Agency
(ECHA) six-month public consultation
period ended in September
2023. It concerned a proposal
by fi ve European Union member
states to ban the sale, production,
use and import of per- and polyfl
uoroalkyl substances (PFAS).
There were more than 5,600
comments and information submitted
by 4,400 interested parties,
relating to more than 10,000
PFAS types. An 18-month transition
period is due once a PFAS
ban comes into force.
Some fi ve- or 10-year " time-limited
derogations " beyond the
18-month period may be permitted
" based on socioeconomic
considerations and availability
of alternatives. "
Freudenberg Sealing Technologies
(FST) has concerns about
Fluorine Kautschuk Material
(FKM) vinylidene fl uoride-based
vulcanized rubber and polytetrafl
uoroethylene (PTFE) use in
many seals, and PTFE in gas diffusion
layer membranes in proton
exchange membrane fuel cells.
The Organization for Economic
Co-operation and Development
considers polymers such
as FKM and PTFE - as mainly
used by FST - to be " polymers
of low concern. " FST nevertheless
commissioned Freiburg, German-based
Fraunhofer Institute
for Mechanics of Materials (IWM)
to report on the " replacement of
polymeric PFAS in industrial applications
with harsh environments, "
which it did in 2023. FST
also uses PVDF, FEP, FFKM and
FVMQ as base materials for some
of its sealing materials.
In its 49-page report, IWM
concluded: " A full replacement
of PFAS in the sealing industry
is currently unfeasible without
facing signifi cant losses in material
properties, performance and
product longevity. "
FST states: " We expect there
will be very few cases, if any at
all, where a [one-to-one] substitute
is currently available and
which meets performance, service
life and other requirements
for use in our products. "
IWM cites polymer scientists
who have concluded that " replacing
FKM in propeller shaft
seals is practically not realistic
and will require at least many
years of research. "
FST has already made changes
to overcome the potential ban,
however, as a part of " risk mitigation
efforts. " It developed an
OMK-PU 30500 two-piece mobile
hydraulics piston seal in 17 sizes
for tractors, excavators and forklift
trucks in a new blue hydrolysis-
and glycolysis-resistant,
high-performance 98 AU 30500
thermoplastic polyurethane
(TPU). It can replace most PTFE
piston seals and is combined
with a non-PFAS inner elastomer
O-ring " energizer " seal. The IWM
report states: " Pressure resistance
of PTFE hydraulic seals is
signifi cantly higher than that of
elastomer or TPU seals. "
The new FST TPU-based seal
solution can withstand operating
temperatures of -35° to 120° C
(-31° to 248° F) and has 20 times
better leakage performance. Materials
Development
Manager
Jürgen Hieber adds: " The material
even offers a further important
advantage, namely that
it makes previously unfeasible
low-friction and hydrodynamically
optimized sealing geometries
possible in future. "
According to Engineering and Innovation
Manager Martin Goerres,
there is also interest in the new seal
material in food and packaging.
PEEK
Thornton Cleveleys, England-based
Victrex plc (A44106)
presents its beige-colored
polyetheretherketone as a halogen-free
alternative to white-colored
PTFE when properties required
include biocompatibility,
chemical, temperature and electrical
resistance and self-lubricating
wear resistance. It adds
that although PEEK can perform
additional structural roles because
it is " stronger and stiffer, "
this may not always be required.
But PEEK is easier to process,
has lower specifi c gravity of 1.3
compared with 2.16 for PTFE,
lower smoke toxicity and slightly
higher melt temperature of 343°
C (649° F), against 335° C (635°
F) for PTFE.
PEEK is also an alternative to
PCTFE and PVDF fl uoropolymers.
Victrex admits that " a small number "
of Victrex PEEK products
contain PTFE as an additive. But
third-party companies produce
them, with apparent compliance
with EU 2019/1021 POPs PFOA
regulations.
With
its Vestakeep-brand
PEEK, Essen, Germany-based
Evonik Industries AG (A4-4118)
has referred to a statement by
German Chancellor Olaf Scholz
as a " welcome turn to the chemical
industry " when he visited
the company's Marl, Germany,
production site at the end of August.
Scholz said he would take
a " pragmatic approach to PFAS
legislation that does not hinder
Germany's industrial
development
but promotes it. "
Nevertheless, Evonik is concerned
and warns of potential
value chain disruption and serious
impact on applications
in batteries, semiconductors,
electric vehicles and renewable
energy generation. Specifi cally,
Evonik said: " We fi nd it troubling
that the proposed restriction apparently
makes no exception for
PFAS use in an industrial context.
As PFAS-coated pipes, vents and
seals could be prohibited only
1.5 years after the restriction
takes effect, this would impact
the entire industry. "
LSR
Liquid silicone rubber could
benefi t from a PFAS ban.
Bernhard Hennrich, injection
molding research manager at
Würzburg, Germany-based research
institute SKZ Süddeutsches
Kunststoffzentrum (B3-3000)
said: " The impending PFAS ban
and increased requirements in
e-mobility will continue to drive
forward possible applications
of liquid silicone. The material
is enjoying increased demand,
particularly in the fi eld of sealing
and electrical insulation. "
A new non-PFAS TPU seal from FST is used in mobile
hydraulic equipment 02 FST OMK 30500 piston seal
used by UTI. Freudenberg Sealing Technologies photos
In a 2021 IKV.Impulse webinar
on hydrogen technologies, Jürgen
Emig, FST hydrogen applications
development manager, included
LSR in a list of bipolar plate stack
seal materials, alongside EPDM,
FKM and fuel cell polyethylene.
LSR was shown as outperforming
FKM in low temperature
performance, low hardness, processing
and " fuel cell poisoning
behavior. " But FKM outperformed
LSR in compression stress relaxation,
gas permeation, durability
and media resistance to coolant,
water and acids. This comparison
confi rmed that one-to-one
PFAS substitution is not easy.
Molding bipolar plate stack seals at
Freudenberg Sealing Technologies.
Plastics News - Show Daily - October 15, 2024

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