BYK内部公司培训资料-消泡剂作用原理
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hydrophilic polar
Surfactant
Foam Stabilization by Surfactants
8/3/2020, Page 9, Defoamer
Types of Foam
Wet foam
Dry foam
8/3/2020, Page 10, Defoamer
Electrostatic Repulsion
• Defoamer: E > 0 and S > 0
F = Surface tension of fluid int = Interfacial tension fluid/defoamer D = Surface tension of defoamer
8/3/2020, Page 16, Defoamer
8/3/2020, Page 3, Defoamer
Foam Prevention • Optimization of production process • Wetting of solid particles • Minimize utilization of foam stabilizing components • Adjusting application conditions
8/3/2020, Page 18, Defoamer
Composition of Mineral Oil Defoamers
Mineral oil Hydrophobic particles Emulsifier Modified polysiloxanes
% 85 - 95
1 -3 3 -6 0,5 - 3
8/3/2020, Page 2, Defoamer
Causes for Foam Bubbles • Adsorbed air (pigments, extenders) • Reaction bubbles (e.g., carbon dioxide in PU systems) • Incorporated air (production, application) • Air from the substrate (wood, concrete, ...)
Defoamer
Wesel, 2007, Max Mustermann
Content • What is foam - foam stabilization • Mode of action of defoamers • Defoamer classes • Defoamer test methods
++ ++ ++ ++ ++
8/3/2020, Page 11, Defoamer
++ ++ ++ ++ ++
>10 nm
Defoamers: Mode of Action
8/3/2020, Page 12, Defoamer
Spreading of DefoHale Waihona Puke Baidumer
8/3/2020, Page 13, Defoamer
• Marking water surface with inert powder
• Adding one droplet of defoamer
Rapid spreading
Spreading of Defoamer (Slow-motion)
8/3/2020, Page 14, Defoamer
BYK-033 BYK-034
Interior paints Industrial
Plasters
emulsions
Gloss and semigloss paints
Alkylphenol-ethoxylate-free defoamers
BYK-031 BYK-035 BYK-037 BYK-038
Defoaming
8/3/2020, Page 17, Defoamer
Defoamer Classes for Aqueous Systems • Mineral oil defoamers • Silicone defoamers • Silicone-free polymeric defoamers
Emulsion production
Emulsion type
100% 100%
Contains silicone
No Yes
w/o
No
100%
Yes
w/o
Yes
100%
Yes
good
excellent
8/3/2020, Page 21, Defoamer
Defoaming
8/3/2020, Page 15, Defoamer
Definition: Entering and Spreading Coefficient
• Entering coefficient E = F + int - D
• Spreading coefficient S = F - int - D
8/3/2020, Page 19, Defoamer
Defoaming Through Hydrophobic Particles
Hydrophobic particle
Foam lamella
8/3/2020, Page 20, Defoamer
Destabilization
Mineral Oil Defoamers for Emulsion Paints and Plasters
Pure liquids do not foam !
8/3/2020, Page 6, Defoamer
No Foam in Pure Water
8/3/2020, Page 7, Defoamer
Foam Stabilization
8/3/2020, Page 8, Defoamer
hydrophobic non-polar
8/3/2020, Page 4, Defoamer
Bubbles Rise to Surface
8/3/2020, Page 5, Defoamer
V
~
_r_2
V = Velocity of rise r = Bubble radius = Viscosity of liquid
Bubbles Break at Surface
Surfactant
Foam Stabilization by Surfactants
8/3/2020, Page 9, Defoamer
Types of Foam
Wet foam
Dry foam
8/3/2020, Page 10, Defoamer
Electrostatic Repulsion
• Defoamer: E > 0 and S > 0
F = Surface tension of fluid int = Interfacial tension fluid/defoamer D = Surface tension of defoamer
8/3/2020, Page 16, Defoamer
8/3/2020, Page 3, Defoamer
Foam Prevention • Optimization of production process • Wetting of solid particles • Minimize utilization of foam stabilizing components • Adjusting application conditions
8/3/2020, Page 18, Defoamer
Composition of Mineral Oil Defoamers
Mineral oil Hydrophobic particles Emulsifier Modified polysiloxanes
% 85 - 95
1 -3 3 -6 0,5 - 3
8/3/2020, Page 2, Defoamer
Causes for Foam Bubbles • Adsorbed air (pigments, extenders) • Reaction bubbles (e.g., carbon dioxide in PU systems) • Incorporated air (production, application) • Air from the substrate (wood, concrete, ...)
Defoamer
Wesel, 2007, Max Mustermann
Content • What is foam - foam stabilization • Mode of action of defoamers • Defoamer classes • Defoamer test methods
++ ++ ++ ++ ++
8/3/2020, Page 11, Defoamer
++ ++ ++ ++ ++
>10 nm
Defoamers: Mode of Action
8/3/2020, Page 12, Defoamer
Spreading of DefoHale Waihona Puke Baidumer
8/3/2020, Page 13, Defoamer
• Marking water surface with inert powder
• Adding one droplet of defoamer
Rapid spreading
Spreading of Defoamer (Slow-motion)
8/3/2020, Page 14, Defoamer
BYK-033 BYK-034
Interior paints Industrial
Plasters
emulsions
Gloss and semigloss paints
Alkylphenol-ethoxylate-free defoamers
BYK-031 BYK-035 BYK-037 BYK-038
Defoaming
8/3/2020, Page 17, Defoamer
Defoamer Classes for Aqueous Systems • Mineral oil defoamers • Silicone defoamers • Silicone-free polymeric defoamers
Emulsion production
Emulsion type
100% 100%
Contains silicone
No Yes
w/o
No
100%
Yes
w/o
Yes
100%
Yes
good
excellent
8/3/2020, Page 21, Defoamer
Defoaming
8/3/2020, Page 15, Defoamer
Definition: Entering and Spreading Coefficient
• Entering coefficient E = F + int - D
• Spreading coefficient S = F - int - D
8/3/2020, Page 19, Defoamer
Defoaming Through Hydrophobic Particles
Hydrophobic particle
Foam lamella
8/3/2020, Page 20, Defoamer
Destabilization
Mineral Oil Defoamers for Emulsion Paints and Plasters
Pure liquids do not foam !
8/3/2020, Page 6, Defoamer
No Foam in Pure Water
8/3/2020, Page 7, Defoamer
Foam Stabilization
8/3/2020, Page 8, Defoamer
hydrophobic non-polar
8/3/2020, Page 4, Defoamer
Bubbles Rise to Surface
8/3/2020, Page 5, Defoamer
V
~
_r_2
V = Velocity of rise r = Bubble radius = Viscosity of liquid
Bubbles Break at Surface