{"id":14212,"date":"2023-04-26T06:05:08","date_gmt":"2023-04-26T12:05:08","guid":{"rendered":"https:\/\/www.ulprospector.com\/knowledge\/?p=14212"},"modified":"2023-06-19T12:51:22","modified_gmt":"2023-06-19T18:51:22","slug":"pc-acrylic-resin-fundamentals-2","status":"publish","type":"post","link":"https:\/\/ulprospector.ul.com\/14212\/pc-acrylic-resin-fundamentals-2\/","title":{"rendered":"Acrylic Resin Fundamentals"},"content":{"rendered":"

\"acrylicThe global acrylic coating market size is estimated to be approximately 60,000 million in USD with CAGR of over 4% until 2030. Coatings utilizing acrylic resins<\/a> and oligomers are the leading polymer technology in the coatings industry, being utilized in large market segments including architectural, automotive OEM, automotive refinish, traffic marking coatings, floor finishes and product finishes. Major applications include use in waterborne<\/a>, solvent borne<\/a>, powder<\/a> and light cure coatings<\/a> and contain one or more acrylate, methacrylate and\/or other vinyl monomers to synthesize a copolymer or terpolymer. Acrylic polymers<\/a> as a class provide good weather resistance, resistance to hydrolysis, gloss and color retention in exterior applications. Due to their versatility and performance, acrylic coatings account for over 25% of all coatings with global sales estimated to approach $25 billion. Acrylic resins<\/a> and acrylate functional materials can be thermoplastic or thermoset and are used in organic solvent born, waterborne, powder and radiation-curable coatings.<\/p>\n

\"Table<\/p>\n

\"The<\/p>\n

The Fox equation provides an estimate of the Tg of a polymer and can be calculated as the sum of the weight fractions of the individual monomers in the copolymer. Tg (1), Tg(2), Tg(3)\u2026.etc. are the Tg<\/sub> in degrees Kelvin of their high molecular weight homopolymers.<\/p>\n

\"Relationship<\/p>\n

As Table 1 suggests, the glass transition temperature of the monomers selected for synthesis of a resin can be selected to enhance multiple properties that may include weather resistance, moisture resistance, resistance to oxygen permeation, flexibility, reactivity, cure and hardness. Most acrylic copolymers are comprised of three or more different monomers that are selected for the desired performance. For example, methyl methacrylate is commonly used to adjust the desired glass transition temperature (Tg), whereas BA and 2-EHA are used to provide hydrophobicity and to lower the Tg. Isobornyl Methacrylate<\/a> is an anomaly as it provides a low viscosity even though the Tg of its homopolymer is high and is used as a partial replacement for MMA. IBMA is used in resins for automotive clearcoats. Methacrylic acid and acrylic acid provide polarity and hydrophilicity and can also improve adhesion to metal. Methacrylic and acrylic acid are used in the 1 \u2013 2% range in emulsion formulations, at much higher levels these monomers increase the water solubility of the acrylic polymer.<\/p>\n

Three broad classes of liquid coatings utilizing acrylic resins<\/a> include thermoplastic, thermoset and waterborne. Acrylic resins can be synthesized by numerous methods; including RAFT (Radiation-induced controlled polymerization, FRP (Free Radical Polymerization) or ATRP (Atom Transfer Radical Polymerization), and for Waterborne acrylic resins, the polymerization methods include emulsion, solution, bulk and suspension. Whereas powder coatings<\/a> utilize solid acrylic resins in powder form.\u00a0 These include acrylics functionalized with Glycidyl Methacrylate<\/a> to crosslink with a dicarboxylic acid<\/a> such as dodecanedioic acid or a carboxylic acid functional resin. Carboxyl functional acrylic powder coatings can also be cured with hydroxyalkyl amides. Lastly, some powder coatings also employ hydroxy functional acrylics for crosslinking with a blocked isocyanate or glycoluril.<\/p>\n

Multiple polymeric architectures can be achieved with acrylic polymers and including graft, block, random, star, brush, hyperbranched and functional polymers.<\/p>\n

\"Linear<\/p>\n

Acrylics can also be functionalized (Table 2) with a variety of monomers to provide additional performance benefits.\u00a0 As Table 2 indicates, being able to functionalize an acrylic resin with a wide range of functional moieties offers the ability to tailor the performance of the copolymer to provide improved adhesion over a variety of substrates, improved pigment wetting; and\/or the ability to crosslink with a suitable reactant like an amino or isocyanate functional crosslinker in a single or two-component system. Other acrylic monomers are also available to impart sulfonic acid, or phosphoric acid functionality.<\/p>\n

Functional monomers<\/a> are used for multiple purposes which may include one or more of the following to enhance performance in ambient cure or thermoset coatings:<\/p>\n