Mineral oil defoamer vs. polyether defoamer
1. Basic chemical structure and defoaming mechanism
1. Mineral oil defoamer (hydrocarbon defoamer, often compounded with hydrophobic white carbon black and emulsifier)
Main body: paraffin based/naphthenic mineral oil+hydrophobic silica+non-ionic emulsification system
Defoaming principle: mineral oil penetrates into foam liquid membrane, replaces foam surfactant, and destroys the elasticity of liquid membrane; White carbon black particles puncture the foam film. Belongs to non-ionic oil phase defoaming system.
2. Polyether defoamer (polyethylene oxide propylene oxide block copolymer, PEO-PPO)
Main body: Block polymerization of ethylene oxide and propylene oxide;
Subdivision: GP type, PPE type, EP type, random polyether.
Defoamer principle: relying on cloud point characteristics. When the temperature is higher than the cloud point, polyether will separate out from the water, forming tiny oil drops and destroying the foam interface; Low temperature solubility in water, no defoaming ability, and effective precipitation after heating. Pure polyether does not contain mineral oil or silicon.
Addendum: The market also has polyether modified organosilicon, which does not belong to the above two categories and should not be confused.
2. Comparison of core performance item by item
1. Defoamer ability and anti foaming ability
- Strong foam breaking: the large foam that has been generated can be eliminated quickly;
- Foam suppression is general: continuous foam generation system, long-term inhibition of foam is weak;
- Under high shear conditions, it is easy to emulsify and fail, and the foam inhibition attenuation is significant under continuous stirring.
- Weak bubble breaking, the speed of eliminating existing bubbles is not as fast as mineral oil;
- Excellent long-term foam suppression, suitable for continuous foam generation;
- Resistant to continuous stirring, shear resistance, and long-term system stability.
2. Compatibility (the most critical pain point of paint film, a key focus of the paint industry)
The polarity of mineral oil differs greatly from that of acrylic acid lotion and resin. Excessive addition can easily lead to shrinkage, fisheye, loss of gloss, decreased gloss, decreased interlayer adhesion, and poor recoating. Especially for high gloss topcoats, varnishes, and decorative coatings, use with caution.
Adjustable polarity, excellent compatibility with water-borne acrylic acid, waterborne epoxy, polyurethane lotion; Reasonable addition causes minimal loss of gloss and shrinkage, suitable for high gloss systems, varnishes, and thin topcoats.
3. Temperature resistance characteristics
Suitable for temperatures < 80 ℃; High temperature is prone to volatilization and migration; Mineral oil above 100 ℃ is prone to volatilization and decomposition, losing its defoaming effect.
With a wider temperature resistance range (usually 80-120 ℃); Suitable for baking water-based industrial paints and high-temperature slurry systems; But it must be above the cloud point temperature to defoam!
Important knowledge point: Polyether below the cloud point has almost no defoaming effect at room temperature.
4. Impact on the water resistance and scrub resistance of the system
Belongs to inert hydrocarbon oil and remains inside the paint film: it reduces the water resistance, salt spray resistance, and scrub resistance of the paint film, and is prone to oil leakage and whitening in the later stage. It is strictly prohibited to use it in large quantities in exterior wall paint, anti-corrosion water-based industrial paint, expansion fireproof coating, and high water resistance systems.
Molecules with ether bond polar groups do not continuously migrate or precipitate; The negative impact on the water and weather resistance of the paint film is much smaller than that of mineral oil.
5. Stable foam/side effects, interaction with other additives
Easily conflicts with hydrophobic dispersants and high HLB emulsifiers; Excessive use can easily cause surface oil shrinkage.
Some polyethers have certain surface activity, and excessive amounts can actually increase foaming; Not sensitive to pH, but when exposed to high concentrations of electrolytes (such as APP polyphosphate ammonium and other flame retardant powders), some polyethers will precipitate.
6. Transparency and Applicability of Varnish
Prone to causing varnish turbidity and haze;
Preferred for clear varnish and high gloss paint, not prone to fogging.
7. Cost
Equivalent effective dosage: Mineral oil defoamer has a lower price;
Equivalent effective dosage: Polyether has a higher unit price.
3. Applicable Scenario Division (Practical Guide for Coatings/Slurry Industry)
Mineral Oil Defoamer Scenarios
- 1. High filling thick slurry system: interior wall putty, thick slurry primer, mortar coating, floor thick coating primer;
- 2. Industrial primer with matte, low gloss, and low appearance requirements;
- 3. Intermittent production, centralized elimination of foam (no need for long-term foam suppression);
- 4. Water based ink, paper coating, and building pulp;
Polyether Defoamer Scenarios
- 1. High gloss topcoat, transparent varnish, self crosslinking acrylic system, decorative coating;
- 2. Water based industrial paint (single/two-component water-based acrylic, water-based epoxy topcoat);
- 3. Water based baking paint that needs to be baked;
- 4. Expansion type water-based fireproof coating (key! Mineral oil can seriously damage the carbon layer, reduce the expansion ratio, and affect temperature resistance. Polyether or polyether modified silicon are commonly used in the industry);
- 5. Continuous production line, continuous stirring and continuous foam production conditions;
- 6. High end coatings for interior and exterior walls with requirements for appearance, gloss, recoating ability, water resistance, and weather resistance;
- 7. Synthesis of lotion, defoaming of polymerizer (polyether used for production of many acrylic lotion).
4. Summary of high-frequency classic problems in the industry
Pursuing ultimate foam suppression and selecting polyether; Pursuing rapid breaking of large bubbles to select mineral oil.
Post time: Jul-31-2026