Acrylic Resins: Synthesis, Properties and Applications
Acrylic resin is an important type of polymer, prepared from the copolymerization of acrylates, methacrylates and other olefinic monomers. These resins are broadly defined to include polymerized methacrylic acid and its derivatives, as well as homopolymers and copolymers. Homopolymers include poly(meth)acrylic acid and its salts, polymethyl(meth)acrylate, butyl ester, polyacrylamide, polyacrylonitrile, etc. According to needs, different types and proportions of monomers can be used to synthesize various copolymer. In addition, acrylic resin can be prepared into different forms of resin such as solid, solution and latex according to different polymerization methods, and is suitable for a variety of different application fields. These resins can be dissolved in a variety of organic solvents such as aromatics, esters and ketones.
Acrylic resins can be produced using a variety of methods, including emulsion polymerization, suspension polymerization, and bulk polymerization. Emulsion polymerization is formed by polymerizing monomers, initiators and reaction solvents. The reaction solvent can be benzene (such as toluene or xylene) or ester (such as ethyl acetate or butyl acetate). This method can prepare resin solutions with a solids content of 50%. In addition, acrylic resins prepared by bulk polymerization have high purity and recommended product stability.
The main band of the spectrum in which acrylics absorb light lies outside the solar spectrum, so acrylic paints have excellent lightfastness and outdoor aging resistance.
According to different structures and film-forming mechanisms, acrylic resins can be divided into two types: thermoplastic and thermosetting. Thermoplastic acrylic resins do not undergo further cross-linking during film formation. The relative molecular weight of this type of resin is relatively high. For example, the weight average molecular weight Mw is usually between 8,000 and 90,000, while the number average molecular weight Mn of ordinary hydroxy acrylic resin is approximately between 1,000 and 20,000. Thermoplastic acrylic resin has excellent gloss retention, color retention, water resistance, chemical resistance, fast drying speed and convenient construction. Therefore, it is widely used in automobiles, electrical appliances, machinery, construction and other fields.
Thermosetting acrylic resin is based on acrylic monomers (such as methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, etc.) and is cross-linked to form a three-dimensional network structure. Insoluble and infusible acrylic polymer. Cross-linking can be achieved in two ways: one is the reaction cross-linking type, which requires the addition of a cross-linking resin with at least two functional groups (such as amino resin, epoxy resin, polyurethane, etc.) to achieve cross-linking and curing; the other is Self-crosslinking type, the polymer chain itself contains two or more reactive functional groups. When the temperature is raised to a certain temperature, these functional groups can react with each other to complete cross-linking. Thermosetting acrylic paint has the characteristics of high fullness, good gloss, high hardness, strong solvent resistance, and good weather resistance. It will not change color or yellow when baked at high temperatures. Used in conjunction with amino resin, amino-acrylic baking paint can be prepared, which is widely used in the manufacturing of automobiles, motorcycles, bicycles, coiled steel and other products.
In short, acrylic resin is a multifunctional resin that plays an important role in various application fields. By selecting different types of acrylic resin and the ratio with other ingredients, diversified performance requirements can be achieved to meet the needs of different fields. With the continuous advancement of science and technology, acrylic resin and its application fields will continue to expand, providing more innovations and solutions for various industrial applications.
