To provide a powder coating material causing little cohesion and aggregation of the powder coating particles during storage, giving a coating film having excellent smoothness, gloss, hardness, scratch resistance, acid resistance and solvent resistance, especially having distinct superiority to a powder coating material to use a dodecanedioic acid linear poly acid anhydride as a hardener, having low hydrolyzability of the hardener A present in the powder coating material and high stability as a coating raw material.
The thermosetting powder coating composition contains (A) a tetradecaneodioic acid linear poly acid anhydride having a residual nitrogen concentration of ≤150 ppm, an average condensation degree of ≥2 and an ash concentration of ≤1,000 ppm and produced by using a linear aliphatic dibasic acid having a tetradecanedioic acid content of ≥90 wt.% and obtained from a n-paraffin mixture composed mainly of 14C fractions by fermentation method and carrying out a condensation reaction of the linear aliphatic dibasic acid having high tetradecanedioic acid content and (B) an epoxy resin exhibiting solid state at normal temperature, containing glycidyl group and having an epoxy equivalent of 200-2,000 g/eq and a number-average molecular weight Mn of 300-8,000.
HIROSE YOSHIHARU
ASAMI KEIICHI
