New Sol-Gel Based Silane Systems for Metal - Smart Formulating

Resins
New Sol-Gel Based Silane Systems
for Metal Treatment Formulations
Established surface pretreatment processes – chiefl y
chro matization and phosphatization – are of utmost economical
signifi cance. The drawback of these otherwise
very eff ective methods, however, is the poor environmental
compatibility, since they work with aggressive
media. Processing techniques involving substances containing
chromium(VI) are especially problematic. Due to
new legal provisions, the use of chromatization processes
with chromium(VI) is no longer approved in many industries.
Silane based systems off er an attractive alternative
to these processes. Silanes are not the only alternative
metal pre-treatment system, but they provide the benefi t
being particularly environmentally benign.
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to passivate the surface by reaction of the silane with the
metal surface
to form a hydrophobic protection layer
to adhere to the next layer via reaction with a subsequent
coating
Passivation of metal surface
due to reaction with the metal
substrate
Further functionality is added to a metal pre-treatment
system by various additives and other ingredients chosen
by the formulator. In addition, they can o� en be added to
existing formulations to improve performance.
Multifunctional Silane Systems Provide the Basis for
Many Formulations
It is for the variability of the diff erent applications in
the metal treatment area that Evonik has developed the
range of Multifunctional Silane Systems. These silane
systems combine a variety of functions in a single product.
One of the most successful examples is the Dynasylan®
HYDROSIL product family. Products of this series
are water-based silanes that, although highly reactive,
are storage stable. This product range is now being
supplemented by the latest generation of Multifunctional
Silane Systems, the Dynasylan® SIVO products.
Accordingly, this new product line is being launched
with the release of the first water-based modularly
structured sol-gel system under the Dynasylan® SIVO
brand name. Each of these products has a diff erent area
of application.
Additives
Coloring
Crosslinkers
Matting
Resin Components
Resins
10 Smart Formulating Journal
Metal substrate
Adhesion promoter for a
subsequent coating
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Hydrophobic inner layer
Barrier layer for chloride
and water
Test substrates with and without primer on aluminum and steel were placed into the salt spray chamber and regularly observed for corrosion.
Multifunctional Silane Systems are designed for most
metal surfaces. Preferred substrates include aluminum,
steel, zinc, phosphatized and other treated metal
surfaces. For the customer, the new technology means
much easier processing and easier waste disposal. Heavy
metal waste is commonly very restricted and costly to
dispose of, and local regulations o� en make waste management
costly and complex. A reduction in the complexity
of the treatment process also reduces costs, as
for example a rinsing step a� er silane application can
o� en be avoided.
Substrate Pretreatment
with Dynasylan®
Evonik has designed a range of Multifunctional Silane
Systems for a multitude of applications and uses.
For use as adhesion promotion primer and additive in
many corrosion protection formulations there are the
products from the Dynasylan® HYDROSIL range. The
SIVO® SOL Technology is an inorganic binder system
with specifically designed additives that can be
used to formulate a large range of diff erent corrosion
and coating systems. The most advanced new system,
Dynasylan® SIVO 160, is for use in conversion coatings
on aluminum.
Coating Curing Temperature (°C) Advantage
Sand blasted steel SIVO 110 + SIVO 111 Polyester powder coating 200 Improved durability and
corrosion resistance
Hot dip galvanized steel SIVO 110 +
Acrylic Dispersion
Aluminum 6061 HYDROSIL 2909
5 % in DI water
Electro galvanized steel HYDROSIL 2909
5 % in DI water
Cold rolled Steel HYDROSIL 2909
5 % in DI water
Aluminum SIVO 160
1 % in DI water
Aluminum SIVO 160
1 % in DI water
Polyester powder coating 200 Improved durability and
better adhesion
2K PUR
(solvent based)
2K PUR
(solvent based)
2K PUR
(solvent based)
2K Epoxy primer
(solvent based)
Reactive PUR powder
coating
60 Excellent corrosion
protection
60 Excellent corrosion
protection
60 Excellent corrosion
protection
60 Excellent corrosion protection,
equal to chromate
140 Excellent corrosion protection,
similar to chromate
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Dynasylan® for Corrosion Protection
The corrosion protection properties are equal to or better
than with traditional pre-treatment systems, e. g. iron
or zinc phosphate and chromate. Dynasylan® HYDROSIL
can be applied directly on cleaned bare metal surfaces.
The application of Dynasylan® HYDROSIL doesn't
require as many steps as traditional pre-treatments,
which improves the effi ciency of the process and leads
to signifi cant cost savings. The thickness of a Dynasylan®
HYDROSIL layer (o� en much less than 1 µ) is considerably
thinner than with traditional pre-treatment systems.
SIVO® SOL Technology consists of four components
resulting in formulating fl exibility for the user. The base
component is a nearly VOC-free inorganic resin, with
a long shelf life. This base component, called Dynasylan®
SIVO 110, is an inorganic particle containing condensed
organofunctional siloxane oligomer. It allows for
the formulation of a large number of pre-treatment and
coating systems, from transparent oleophobic inorganic
top-coats to corrosion protection systems. A range of
additives has been designed specifi cally for use with the
Dynasylan® SIVO 110 binder. The additives can be used
to formulate diff erent types of metal pre-treatment or
coating systems. The additive Dynasylan® SIVO 111 is
a neutralizing agent for formulations to be applied on
steel. Dynasylan® SIVO 112 is a hydro and oleophobation
additive that allows for the formulation of oleophobic
topcoats. Dynasylan® SIVO 113 is a hydrophobizing
additive that can be used to signifi cantly increase weatherability
of the coating.
Dynasylan® SIVO 160
Dynasylan® SIVO 160 is a new water-based silane system
which is especially eff ective for the pre-treatment of aluminum.
It is nearly VOC free and was designed to be highly
reactive and to cure at a relatively low temperature. This
enables the use of this new sol-gel system in many fi elds
where high temperatures are prohibitive. Dynasylan®
SIVO 160 reacts with the metal surface and forms a very
tight inorganic-organic network which forms an excellent
corrosion protection system in combination with an
organic topcoat. The product can be applied by industry
standard methods such as spraying or immersion.
Furthermore, Dynasylan® SIVO 160 is a new versatile
component for formulation and thus can be formulated
with components of the SIVO® SOL Technology and the
Dynasylan® HYDROSIL products. It allows high formulation
fl exibility for special applications.
Technical Contact
NAFTA: ramon.sanchez-morillo@evonik.com
Asia: frank.gao@evonik.com
Europa / ROW: phillipp.albert@evonik.com