What Is Alkyd Coating?
Alkyd Coatings are room-temperature drying paints made primarily from alkyd resins, which are ester compounds of polybasic acids like phthalic anhydride and polyhydric alcohols such as glycerin. These are modified with various oils and fatty acids to enhance paint quality.
Modified Alkyd Coatings include variations with silicone resin, epoxy resin, and styrene monomer, offering improved adhesion, weather resistance, and pigment dispersion. They exhibit good color and gloss retention, and the coating film is highly resistant to water, solvents, and heat.
Applications of Alkyd Coating
Alkyd Coating is widely used for finishing and protective coatings due to its quick-drying, adhesive, impact resistance, and durability properties. It’s utilized in indoor and outdoor coatings, building materials, steel structures, ships, vehicles, and metal coating for large electrical equipment, machine tools, agricultural equipment, and woodworking.
Characteristics of Alkyd Coating
Alkyd Coating contains unsaturated fatty acids like linseed oil, soybean oil, and castor oil. Depending on the fatty acid content, they are categorized as long-oil, medium-oil, or short-oil. Short-oil coatings have high gloss and hardness, while long-oil paints are more workable but less resistant to water and chemicals. Medium-oil variants have intermediate properties.
During drying, alkyd coatings undergo oxidative polymerization, where the dry oil component reacts with air oxygen, forming a tough coating film. This reaction generates heat.