Polyester lacquer is known for its unique ability to form both acyclic and cyclic hydrogen bonds between polymer molecules. These hydrogen bonds can break under external force, absorbing energy (approximately 20–25 kJ per mole), which helps the material withstand mechanical stress. Once the force is removed, the bonds can re-form, allowing the material to recover its original structure. This reversible process gives polyurethane coatings excellent toughness and wear resistance. Compared to other types of paint, polyurethane films exhibit higher elongation at break when hardness is similar, making them ideal for applications like floor coatings, industrial paints, and high-performance decorative finishes.
Unlike some other coatings—such as epoxy or chlorinated rubber, which offer good protection but lack aesthetic appeal, or nitrocellulose lacquers, which are highly decorative but not very protective—polyurethane paint provides a perfect balance of both. It is commonly used on high-end wood furniture, pianos, and even large aircraft due to its durability and visual appeal.
The paint film formed by polyurethane exhibits strong adhesion, similar to epoxy resins, making it an excellent binder. As a result, it adheres well to various materials, including metal, wood, rubber, concrete, and certain plastics. While epoxy may have a slight edge over polyurethane in terms of adhesion to metal surfaces, polyurethane performs better on rubber substrates.
Polyurethane coatings offer adjustable elasticity, ranging from extremely rigid to highly flexible, depending on the formulation ratio. In contrast, traditional coatings like epoxy, unsaturated polyester, or alkyd resins typically struggle to achieve high flexibility without compromising rigidity.
These coatings also demonstrate excellent chemical resistance, withstanding exposure to acids, alkalis, salts, and petroleum products. This makes them suitable for use in harsh environments such as offshore drilling platforms, ships, chemical plants, and storage tanks.
Polyurethane paints can be cured at both high and low temperatures. For example, while epoxy and unsaturated polyester struggle to cure below 10°C, polyurethane can still cure effectively at 0°C, extending its usability across different seasons. Additionally, it cures quickly at room temperature, making it ideal for large-scale projects like oil tanks and aircraft, where performance is crucial.
Special formulations of polyurethane paint can withstand extreme temperatures, from -40°C to high-temperature insulation applications, offering properties comparable to polyimide materials.
Electromagnetic wires coated with polyurethane can be automatically soldered without damaging the coating, making them ideal for use in telecommunications equipment and precision instruments.
Polyurethane paint can be combined with various other polymers, such as polyester, polyether, epoxy, alkyd, polyacrylate, cellulose acetate butyrate, vinyl chloride-vinyl acetate copolymers, asphalt, drying oils, and more, allowing for a wide range of customized solutions.
It is also available in multiple forms, including solvent-based, solvent-free, powder, water-based, single-component, and two-component systems, ensuring that it can meet diverse application needs.
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