*These pre-accelerated Synolite resins cure exclusively with benzoyl peroxide
(BPO).
Car Refinishes Offers High cure speed, excellent adhesion!
The majority of DSM putty resins are tailor made for car repair application,
with a complete range of Synolite resins for knifing fillers and spray putties.
Knifing fillers
The putties cure with conventional benzoyl peroxide as the hardener, allowing
high curing speed also at lower temperatures. The soft-sanding properties of
Synolite are highly appreciated, as well as its excellent adhesion to a
variety of substrates including steel, aluminium and galvanized steel. The
(semi-)flexible resins Synolite 6494-U-2, 7259-U-2, 2710-U-2 and 5241-U-1 have
a low styrene content (below 35%) to give label-free putties (below 12.5%
styrene in the putty).
The excellent compatibility of Synolite putty resins with various paint
systems in the car refinish process results from the state-of-the-art
polymeric amine cure systems.
In response to specific customer needs, the ready-for use resins Synolite
6494-U-2 and Synolite 7259-U-2 are available which give high technical
performance and easy logistics (only one resin needed). Alternatively, blends
can be made with Synolite 9248-U-3 for boosting of e.g. mechanical strength
and curing speed at lower temperatures. Blends with Synolite 2710-U-2 or
Synolite 5241-U-1 can be used to increase flexibility in the cured state, and
to give ultra-soft sanding properties of putties.
Spray putties
Spray putties are applied in thin layers, and use conventional cobalt / methyl
ethyl ketone peroxide cure systems. DSM has selected two specialty resins
based on tetrahydrophthalic anhydride for spray putties. Blending of Palatal
P51-01 (40-50 parts by weight) and Palatal E240-02 (50-60 pbw) ensures rapid
curing and excellent adhesion to various substrates.
The Car Refinish Process
The major application area for polyester putties is Car Refinishes. The putty
is part of a total repair system including several coating layers. The purpose
of the putty is to fill pits, scratches, hide damages marks and deep or
superficial dents or other isolated damages on the car body surface prior to
refinish, for >300 micron. Application of a spray putty as the final putty
layer ensures a smooth surface, which is essential to obtain high quality car
refinishes.
The second step in the repair process (Scheme 1) is that in which the first
coat of paint (5-10 micron) is applied by spraying over the abraded steel over
the putty spot, over the abraded steel and over the aged coating system.
The purpose of a filler (50-300 micron, step 3) is to adjust for small
defects, sanding scratches or pores arising in the relatively coarse putty
surface. The binder system for this system is typically hydroxy-functional
acrylic-isocyanate-based and one pack alkyd filler. Finally, the color topcoat
is applied in such a way that nothing of the damage should be visible
afterwards. This can be done in one coat, or alternatively with two coats in
case of metallic effects (two-layer clear-over-base system).
