ADHESIVES
Adhesive
solutions for
automotive
The unceasing push for lightweighting in automotive is seeing adhesives
used where previously mechanical or metal-based solutions were common.
A s automotive
electrification continues
to evolve, powerful
lithium-ion (li-ion) battery
architectures are at the center
of discussions around electric
vehicles. While battery system
designs vary by manufacturer,
the joint performance
objectives for all automotive
battery technologies are longer
lifetime, operational safety, cost
efficiency and reliability. In
their most recent collaboration,
Henkel and Covestro developed
a solution enabling the efficient
fixation of cylindrical li-ion
battery cells inside a plastic cell
holder. The solution is based
on a UV-curing adhesive from
Henkel and a UV-transparent
polycarbonate blend from
Covestro.
With a strong consumer
push to reduce electric vehicle
prices, large-scale and costefficient
li-ion battery cell
assembly is a prerequisite
for every automotive OEM.
As such, Henkel’s Loctite
AA 3963 battery assembly
adhesives and Covestro’s UV
transparent polycarbonate
blend Bayblend were developed
for compatibility with highvolume
automated dispensing
techniques and offer flexible
and fast cure mechanisms. The
acrylic adhesive was formulated
for use with the cell holder,
which is constructed of a
special flame-retardant plastic.
It provides strong adhesion
to the substrate material and
offers production adaptability
through long open times and
short cure cycles.
EFFICIENT AND FLEXIBLE
PRODUCTION
“High-volume manufacturing
operations with short cycle
times and process flexibility
are essential,” explains Frank
Kerstan, Head of e-Mobility
Europe at Henkel. “The Loctite
OEM-approved adhesive
designed to secure cylindrical
li-ion cells into a carrier is a
one-part, cure-on-demand
formulation. After high-speed
dispensing, the material’s
long open time inherently
builds adaptability into the
process by allowing for any
unexpected production
interruption. Once all cells are
placed into the adhesive and
secured in the holder, curing
is activated with ultra-violet
(UV) light and takes place in
less than five seconds.” This
is a major advantage over
conventional manufacturing
where curing times can range
from several minutes to hours,
thus requiring additional
storage capacity for parts.
The cell holders are
manufactured from
Covestro’s PC+ABS blend
Bayblend FR3040 EV. With
a thickness of only one
millimetre, the plastic already
meets category V-0 of the
Underwriters Laboratories’
UL94 flammability rating but
shows good permeability for
UV radiation in the wavelength
range above 380 nanometers.
“The material allows us to
construct dimensionally stable
parts that are necessary for
automated mass assembly,”
says Steven Daelemans,
Market Development
Manager E-Mobility in the
Polycarbonates segment at
Covestro. “Together with the
fast-curing capability of the
Loctite adhesives, this material
combination delivers an
innovative approach to largescale
cylindrical li-ion battery
module production.”
“The material allows us to construct
dimensionally stable parts that are
necessary for automated mass assembly”
20 Issue 2 2020