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Performance Materials
Stefan Kempka
30.10.2009
Introduction RC PSA Additives Wetting Agent
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Wetting agents
Highly viscous dispersions spread smoothly in an
even film as a shrinkage of the film is
prohibited by the viscosity. Systems of low
viscosity are not subjected to these restrictions
and show therefore a tendency to minimize their
surface area.
Wetting agents are therefore needed to accomodate
the surface tension of the dispersion to the one
of the substrate.
Because of their surface active nature their
dosage should be kept low to avoid additional
foam formation and water take up of the
dispersion film .
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Aggregation of Amphiphiles in Solution Geometric
Considerations
critical packing parameter .
V
P
a0 lc
V lipophilic chain volume ao
hydrocarbon/water interfacial area lc
length of lipophilic chain
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Aggregation of Amphiphiles in Solution Geometric
Considerations
lt1/3
1/3 - 1/2
gt1
1/2 - 1
from J.N. Israelachvilli et al., J. Chem. Soc.,
Faraday Trans. II, 72 (1976) 1525-1568
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Surfactant Bilayer Aggregates in Solution
lamellar phase (La)
bicontinous or sponge phase (L3)
vesicles
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Aggregation of Amphiphiles in Solution Geometric
Considerations
micelle-forming surfactants
vesicle-forming surfactants
soluble monolayer
insoluble monolayer
very low unimer solubility
soluble unimers
micellle (thermodynamically stable)
vesicle (thermodynamically unstable)
spontaneous bursting of vesicles at the
monolayer large amount of surfactant available at
the monolayer
equilibrium between surface monolayer
and micelles through exchange of unimers
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Aggregation of Surfactants on Solid Substrates
Estimation of Interfacial Tension
micelle-forming surfactants
vesicle-forming surfactants
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Process of Superspreading
before drop of vesicle solution
after pancake of water with two monolayers of
surfactant
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What kind of wetting agents are available?
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Wetting agents for PSA
Conventional wetting agents sulfosuccinates
O
O
O
-
S
O

Na
O
O
O
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Wetting agents for PSA
(Bubble pressure tensiometer)
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Wetting agents for Polymerdispersions
Alcoholalkoxylates
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Requirements for "Fast" Low-Foaming Surfactants
no long straight alkyl chain (strong
aggregation at surface monolayer stabilizes
foam) small, nonionic headgroup (no
stabilization of foam lamella by Coulomb forces)
alcohol alkoxylate with short and highly branched
alkyl chain sparingly hydrophilic headgroup (few
EO/PO) TEGO Surten W 111
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Wetting agents for PSA
(Bubble pressure tensiometer)
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Wetting agents for PSA
Organo modified siloxane
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Organo modified siloxane - trisiloxane
Their advantages Their advantage is the low
dosage (0.1) at which they are applied compared
to the commonly used sulfosuccinates (1.0). This
is due to their low surface tension and good
spreading behavior. They cause considerably
lower amounts of foam and show synergetic effects
with organo-modified siloxane antifoams.
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Wetting agents for PSA
(Bubble pressure tensiometer)
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Wetting agents for PSA
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Wetting agents for PSA
Silicone polyether vs. sulfosuccinate
mm²
spreading on polypropylene
spreading on glass
0.05 ml were given on the substrate
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Product Portfolio RC PSA Additives
Wetting Agent
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Foam behavior for wetting agents
shaking test (30 shakes in 10s) 0.1
concentration, measurements after 30s
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Tego Surten W
Si-O-C bonded polyether siloxane Si-O-C bonded
silicon wax Si-C bonded polyether
siloxane Si-C bonded silicon wax Si-C
bonded silicon quats und -betaine Si-C bonded
polyether- und alkyl siloxane
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Organo-modified Polysiloxanes Synthesis
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Tegopren Organo modified Siloxanes
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Performance Additives for PSA
Wetting agents
Antifoam

• no surface defects
• good long time efficiency
• no negative influence on adhesive strength
• high performance at low use levels

• low dosages
• low foaming tendency
• suitable even on critical substrates
• improved water take up properties

TEGO Surten A 2-89
TEGO Surten W 5840
TEGO Antifoam and TEGO Surten W together show
up with synergistic effects and therefore improve
the overall performance
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... meet both our customers and their
customers market requirements...

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ispersion.com