Plastic paint defoamer: From microscopic bubble breaking to the invisible promoter of industrial revolution
In the car bumper spraying workshop, the paint without defoamer was entrained in air due to high-speed stirring, forming
dense bubbles on the surface. These bubbles expanded and burst when baked and cured at 180°C, resulting in defects such
as pinholes and orange peel on the surface of the paint film, causing the yield rate to drop sharply to 88%. After scientifically
adding 0.3% of special defoamer, the bubble defect rate can be controlled below 0.3%. This case reveals the core value of
defoamer in the plastic paint industry-it is not only the guardian of paint quality, but also the key technical support for
modern precision manufacturing.
1. Automobile industry: invisible defense line of precision coating
In the coating of automobile interior and exterior decoration, defoamers need to deal with complex scenarios:
Bumper spraying:
Epoxy resin system is prone to produce microbubbles due to high shear force during the dilution stage.
Using polyether modified silicone defoamer, its hydrophobic particles can accurately puncture the bubble nucleus. Under the
stirring condition of 800rpm, 0.2% addition can reduce the foam volume by 95%.
Instrument panel injection molding:
When polycarbonate (PC) materials are molded at 220°C, a heat-resistant defoamer is
required. A new type of core-shell nanoparticle defoamer can maintain continuous defoaming for 24 hours at 200°C, solving the
problem of high-temperature failure of traditional products.
Electrophoretic coating:
Cathodic electrophoretic paint (CED) is prone to bubbles due to its high solid content. Fluorine-modified
silicone defoamers can quickly spread and destroy the elastic film of bubbles by reducing the surface tension to 16mN/m, thereby
improving the thickness uniformity of the electrophoretic layer by 30%.
2. 3C electronics: a bubble-breaking revolution with nano-level precision
In the coating of precision electronic products such as smartphones and tablets, defoamers must meet nano-level precision
requirements:
UV coating of mobile phone shells:
When ultraviolet light-cured coatings (UV) are cured instantly, bubbles will be "frozen" in the paint film due to volume shrinkage.
Temperature/pH dual-sensitive defoamers can remain inert below 80°C, and automatically activate the bubble-breaking function
when exceeding 120°C to solve the pinhole defects of UV coatings.
Laptop keyboard coating: Water-based polyurethane systems are prone to foaming due to surfactant residues. Polyether-modified
silicone defoamers achieve a balance between system compatibility and defoaming efficiency by adjusting the HLB value to 8-10,
which improves the wear resistance of keyboard coating by 40%.
Smart watch glass coating:
Silicon-free defoamers are required for vacuum coating pretreatment. Bio-based defoamers replace petroleum-based raw materials
with castor oil derivatives, reducing VOC content by 80% and avoiding silicon residues affecting coating adhesion.
3. Home appliance industry: Dual optimization of efficiency and cost
In home appliance shell coating, defoamers need to take into account both efficiency and cost:
Refrigerator door spraying:
Acrylic resin systems are prone to produce a lot of foam when stirred at high speed. Mineral oil defoamers
are widely used because of their fast defoaming and good economy. Experimental data show that adding 0.5% of mineral oil defoamers
can reduce the foam volume by 92%, and the coating cost of a single refrigerator can be reduced by 0.12 yuan.
Washing machine inner drum coating:
Powder coatings are prone to produce bubbles due to charge accumulation during electrostatic
spraying. Defoamers containing hydrophobic silica (particle size D50 = 8μm) can effectively puncture the elastic membrane of bubbles,
increase the powder application rate by 15%, and increase the spraying area by 20%.
Anti-mildew coating of air conditioner blades:
Water-based epoxy resin systems require the use of anti-shrinkage defoamers. A defoamer with excellent leveling properties can avoid
the fogging of the paint film caused by excessive defoamers, and increase the pass rate of the moisture resistance test of the anti-mildew
coating to 99%.
4. Special fields: bubble breaking challenges in extreme environments
In special fields such as aerospace and rail transportation, defoamers need to break through technical limits:
High-speed rail body coating:
During the operation of high-speed trains, the body coating needs to withstand the impact of 250km/h
wind speed. A weather-resistant defoamer introduces fluorocarbon segments to enable the coating to maintain defoaming efficiency in
a temperature change environment of -40℃ to 80℃, solving the problem of low-temperature failure of traditional products.
Wind turbine blade coating:
Offshore wind turbine equipment needs to resist salt spray corrosion for a long time. Anticorrosive coating systems containing zinc powder
are prone to foaming due to metal ion catalysis. A modified siloxane defoamer extends the salt spray resistance of the anticorrosive coating
to 5,000 hours by chelating metal ions.
Medical device coating:
Medical-grade defoamers must pass ISO 10993 biocompatibility testing. A polyether defoamer uses food-grade
raw materials, which can meet FDA certification requirements and is used in the production of antirust coatings for surgical instruments.
