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Bubbles generated during coating production or application not only compromise surface smoothness but also reduce adhesion and densification. Key causes include:
Surfactants (e.g., wetting agents) in coatings reduce surface tension. However, air entrapment during stirring or spraying forms stable foam encapsulated by liquid films.
During high-temperature baking, coating viscosity drops, allowing bubbles to rise. Rapid solvent evaporation then solidifies the surface, trapping bubbles as pinholes. High-pressure spraying or roller coating exacerbates air entrainment.
In high-solids or high-viscosity coatings, bubbles migrate slowly, and high elasticity further prevents rupture.
Addressing these challenges requires synergistic defoamer properties and process adjustments:
Chemi Tech defoamers utilize fluorosilicone modifiers to achieve surface tension (≤22 mN/m) lower than coatings, enabling rapid bubble rupture without cratering.
For bake-cure coatings, defoamers withstand ≥150°C without decomposition. Chemi Tech’s polyether-siloxane copolymers ensure continuous defoaming while maintaining compatibility with epoxy/polyurethane systems.
For spray processes, Chemi Tech foam-suppressing defoamers (0.1%~0.3% dosage) inhibit bubble regeneration. For brush/roller applications, fast-defoaming agents shorten bubble duration.
An industrial coating client resolved bubble-induced bumps during high-pressure spraying by:
Adding Chemi Tech defoamers during resin grinding for uniform dispersion;
Reducing spray pressure from 0.6MPa to 0.4MPa to minimize air entrapment;
Achieving 95% reduction in pinholes and surface roughness (Ra) ≤0.3μm.
Effective bubble elimination combines material science and process optimization. Chemi Tech defoamers deliver precise surface tension control tailored to diverse application scenarios, ensuring superior coating quality.
Guangzhou Chemi Tech New Material Co., Ltd.
Address : No. 3 Road, Lanshan Village, Xiancun Town, Zengcheng District, Guangzhou City
Contact : +86-19820415595(Manager Fang)
Tel : +86-13414362583(Manager Lee)
E-mail : crystal@gzchemitech.com