Analysis of Molecular Structure Changes of Baked Epoxy Resin for Steel Coating Using Field Desorption Mass Spectrometry

Abstract

Using field desorption MS, we studied the molecular structures of both pure epoxy resin and epoxy resin with thermal stabilizer, which is used as pre-coated steel.
These experiments show that these epoxy resins are bis-phenol A type, which has usually two glycidyl radicals at both end of molecule, but this resin has only one glycidyl radical at the end of molecule, and hydroxyl radical at the other end. Furthermore, it is also shown that this resin shifts to large part of distribution of molecular weight by being baked both at 270 and 285°C, and that glycidyl radical is taken off and re-coupled molecule is formed. These changes occur sharply at 285°C than at 270°C, without thermal stabilizer. However, with thermal stabilizer, there is less change between these temperatures. Therefore, we conclude that thermal stabilizer is effective.