What are the anti-corrosion properties of waterborne bio-based anti-corrosion coatings?
Publish Time: 2025-08-25
As a new generation of green functional materials, waterborne bio-based anti-corrosion coatings have achieved anti-corrosion performance comparable to, and in some cases surpassing, traditional solvent-based anti-corrosion coatings, becoming a key solution for sustainable development in the industrial and construction sectors. These coatings utilize renewable bioresources (such as vegetable oils, rosin derivatives, and biopolyols) as their primary film-forming materials. Incorporating waterborne dispersion technology, they not only significantly reduce volatile organic compound (VOC) emissions but also achieve long-term protection for metal substrates through molecular structure optimization and a comprehensive anti-corrosion mechanism.The core of their anti-corrosion performance lies primarily in their excellent adhesion. Chemically modified waterborne bio-based resins form strong chemical bonds and physical anchors with metal surfaces such as steel, galvanized steel, and aluminum. This strong adhesion effectively prevents the intrusion of moisture, oxygen, and electrolytes from the coating-substrate interface, serving as the primary barrier against electrochemical corrosion. Furthermore, the coating's dense, uniform coating and low porosity effectively block the penetration of corrosive media. In salt spray tests, high-quality waterborne bio-based anti-corrosion coatings can achieve rust-free performance for over 1,000 hours, meeting the protection requirements for moderate to severe corrosion environments (C3-C4) as specified by international standards such as ISO 9227.The bio-based components in coatings are more than just environmentally friendly alternatives. The long-chain fatty acids, aromatic rings, or hydroxyl groups in their molecular structures participate in cross-linking reactions during film formation, forming a highly cross-linked three-dimensional network. This structure not only enhances the hardness and abrasion resistance of the coating film but also strengthens its resistance to penetration. Water and chloride ions have difficulty penetrating the dense coating film, thus slowing the onset of anodic oxidation and cathodic reduction reactions. Furthermore, some bio-based resins possess a certain degree of hydrophobicity, further reducing the wetting and diffusion rate of water molecules on the coating surface.Waterborne bio-based anti-corrosion coatings are typically formulated with environmentally friendly anti-rust pigments and corrosion inhibitors, such as zinc phosphate, molybdate, or ion-exchange pigments. These ingredients release corrosion-inhibiting ions upon water penetration, forming a passivation film on the metal surface and inhibiting corrosion. Furthermore, some high-end products incorporate nanomaterials (such as nano-silica and graphene oxide) for modification. These nanoparticles fill micropores, extend the diffusion path for corrosive media, and enhance the coating's mechanical strength and resistance to UV aging, thereby improving outdoor durability.Weather resistance is a key indicator of the long-term performance of anti-corrosion coatings. Waterborne bio-based coatings, with an optimized ratio of UV stabilizers and antioxidants, maintain their integrity under prolonged exposure to sunlight, rain, and temperature fluctuations. Their films are resistant to powdering, cracking, or blistering, and exhibit excellent color stability, making them suitable for structures exposed to complex climates, such as bridges, transmission towers, and marine infrastructure. Furthermore, the coatings exhibit excellent flexibility and impact resistance, adapting to subtle metal deformations caused by temperature fluctuations and preventing protective failure due to stress cracking.Application suitability also indirectly impacts anti-corrosion effectiveness. Waterborne systems are environmentally friendly, allowing safe operation under ventilated conditions and reducing the accumulation of harmful gases. Their excellent leveling and permeability ensure uniform coverage of corrosion-prone areas such as welds and corners, preventing missed coatings or thin coatings. The slow evaporation of water during the drying process promotes a denser film structure. Their comprehensive supporting system allows them to be combined with waterborne epoxy primers and polyurethane topcoats to form a multi-layered protection system to meet the needs of projects with varying corrosion levels.In summary, waterborne bio-based anti-corrosion coatings, through advanced resin technology, scientific formulation design, and the synergistic effect of multiple anti-corrosion mechanisms, have achieved superior anti-corrosion performance. They not only meet industrial-grade protection standards but also set new benchmarks in environmental protection, safety, and sustainability. They represent the inevitable transition of anti-corrosion coatings from "high-pollution, high-protection" to "green, high-efficiency protection." With continuous technological advancements, their application scope will continue to expand, becoming a vital force in building green infrastructure.
