Hydroxy-functional acrylic resin
Hydroxyl-functional acrylic resins paired with aliphatic isocyanates give the classic high-gloss, highly weatherable two-component urethane topcoat.
Acrylic polyols are copolymers of acrylic and methacrylic monomers (for example methyl methacrylate and butyl acrylate) with a hydroxyl-bearing monomer such as HEMA or hydroxyethyl acrylate. The hydroxyl content, molecular weight and Tg are tuned by the monomer recipe; products are identified by OH content or equivalent weight rather than a single CAS number.
Acrylic polyols are the backbone of automotive refinish clearcoats and industrial and architectural 2K polyurethane topcoats. Crosslinked with HDI or IPDI polyisocyanates, they deliver gloss, hardness and long-term UV resistance over epoxy or zinc primers.
The all-carbon acrylic backbone resists UV and hydrolysis well, while the pendant –OH groups provide crosslinking sites. Higher hydroxyl content gives denser networks and better chemical resistance; lower gives more flexibility. Solids, viscosity and Tg determine VOC and application behavior.
Acrylic polyols are typically supplied in solvent, so solvent flammability and exposure controls apply. Once mixed with isocyanate, handle as an isocyanate coating.
Both parts are aliphatic: the acrylic backbone and HDI-based hardeners lack the UV-absorbing aromatic groups that cause yellowing.
Yes. Waterborne acrylic polyol dispersions are used with water-dispersible polyisocyanates to make low-VOC 2K coatings.
