Acrylic resins are synthesized by radical polymerization of various monomers and can be used in thermosetting paints when combined with hardeners. Those with a high glass transition temperature are also employed as lacquer-type paints.
1. What is Acrylic Resin?
Acrylic resin is created by the bonding of monomers with double bonds through radical polymerization reactions. The primary component monomer is acrylic acid ester, but other monomers with double bonds, such as styrene and maleic acid ester, may also be used. Acrylic resin is used in applications involving fibers and plastics, and for paint applications, it is synthesized through copolymerization of various monomers, resulting in different properties. New polymerization techniques allow for adjustments in molecular weight and monomer linkages.
Acrylic resin is generally colorless and transparent, offering excellent gloss, weather resistance, water resistance, and chemical resistance. Varieties with a high content of styrene may have poor light resistance and can experience yellowing and cracking. It can be adjusted in various ways, including molecular weight, solubility, and Tg (glass transition temperature) through polymerization conditions and ester groups in the side chains. For instance, longer hydrocarbon side chains result in a lower Tg, a smaller SP value, and better solubility in low-polarity solvents. Additionally, methacrylic acid esters have a higher Tg compared to acrylic acid esters.
Resins with carboxyl, hydroxyl, or epoxy groups in their side chains are used in two-component, room-temperature-curing paints or baking-type paints, with polyisocyanates or melamine resins serving as hardeners. By introducing epoxy groups, curing with dicarboxylic acids or polyamines is possible. When the glass transition temperature is high, it results in a hard, dried paint film and is used as thermoplastic lacquer-type paint. Acrylic resin emulsions are produced through emulsion polymerization and widely used in water-based architectural paints.