Water-based shoe paint defoamers are additives specifically designed for water-based shoe coatings. They achieve
efficient defoaming by destabilizing the foam surface film while maintaining the coating's appearance and performance.
Their application can be summarized in the following key points:
I. Core Function and Mechanism
Rapid Defoaming and Long-Lasting Foam Suppression
Defoamer molecules reduce the local surface tension of the foam, causing the foam film to lose its elasticity and rupture.
Their active components (such as silicones and polyethers) penetrate the double-layer membrane of the bubbles,
accelerating liquid drainage, thinning the foam until it ruptures. For example, silicone defoamers provide continuous
foam suppression over a wide temperature range, while polyethers achieve long-lasting effectiveness through their water
solubility.
Compatibility and Stability
High-quality defoamers must be well compatible with the water-based system to avoid surface defects such as craters
and fisheyes. For example, RK-8401 water-based defoamer is refined through a special process to ensure stable
coexistence with resins, emulsions, and other components in shoe coatings, without affecting film formation and adhesion.
II. Application Scenarios and Advantages
Defoaming During the Production Stage
Resin Synthesis and Pigment Dispersion:
Adding a foam suppressant (such as silicones) during the grinding stage prevents microbubbles generated during mixing
and reduces the risk of pinholes in the subsequent coating.
During the Paint Letdown Stage: Adding a non-silicone defoamer with strong defoaming properties ensures that the paint
remains free of bubbles during
spraying or brushing, improving leveling.
Storage and Transportation Protection
Defoamers suppress foaming caused by temperature fluctuations or the release of volatile organic compounds, preventing
delamination and deterioration of the paint and extending its shelf life.
Optimization During the Application Stage
Airless Spray: Suitable for high-viscosity systems, it prevents foaming caused by pressure fluctuations during spraying and
ensures a uniform coating.
Hand Brushing: Reduces air bubble entrapment, prevents pores on the coating surface, and enhances the appearance and
texture of the shoe material.
III. Selection and Usage Guidelines
Selecting Based on the System
Silicones: They offer high defoaming efficiency (dosage < 0.05%) and are suitable for high-viscosity shoe coatings, but dosage
must be controlled to avoid craters.
Polyether-modified silicones: Combine the advantages of silicones and polyethers, offering excellent defoaming properties
and compatibility, suitable for both clear and pigmented varnishes.
Mineral oils: Low cost, but may affect coating gloss; a trade-off between cost and performance is required.
Dosage and Processing
Recommended Dosage: 0.1%-0.6% of the total formulation, added in two divided doses (1/2 during the grinding stage
and 1/2 during the letdown stage).
Mixing Requirements:
Stir thoroughly before use, ensuring uniform mixing even if no separation occurs. Diluted products should be used
immediately after dilution to avoid long-term storage.
Equilibration Time: Allow at least 24 hours after addition to allow the defoaming performance to balance the risk of edge
shrinkage and cratering in the coating.
Precautions: Risk of Overdosage: Excessive use may result in poor brushability and recoatability.
Environmental Compatibility: Select a defoamer that is temperature- and pH-resistant to ensure stable performance in shoe
production environments (such as high-temperature drying).
IV. Typical Product Examples
RK-8401 Water-Based Defoamer: A milky white liquid with a relative density of 1.112, it is suitable for water-based systems
such as shoe coatings and glass coatings. It offers excellent defoaming and foam suppression, is pinhole-free, and does not affect
recoatability or adhesion.
Silicone-Polyether Composite: Combining high-efficiency defoaming with good compatibility, it is suitable for airless spray
formulations and reduces application defects.
V. Industry Value
Water-based shoe coating defoamers significantly improve coating quality by eliminating foam during production, storage,
and application.
Reduced Rework: Avoids problems such as pinholes and poor leveling caused by bubbles, reducing production costs.
Enhanced Market Competitiveness: Enhances the appearance, quality, and durability of shoe materials, meeting the
demands of the high-end market.
Environmental Compliance: Compatible with the low-VOC characteristics of water-based coatings, helping companies
meet environmental standards.
