Abstract
The synthesis of methacrylate stars by an arm-first process using ethylene glycol dimethacrylate as the core-forming material is described. The level of free arm is an indicator for the extent of termination during the preparation. Using 0.2% (mole basis) of catalyst on initiator instead of higher concentration is helpful. Modifiers for the anion catalyst used in group transfer polymerization (GTP) can be used to reduce termination. Clarity of the two-phase blends with polyester polyol and isocyanate crosslinking agent depended on star composition, hydroxyl-number (OH#) and star level. Recently, benzyl methacrylate has been introduced into this technology to give improved film hardness and clarity with cycloaliphatic polyester coreactants. This permits use of 25–30% star to give fast dry and improved hardness/flexibility balance while also allowing the application at less than 3.5 Ib/gallon of solvent.
Published Version
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