The Curing of Epoxy Resins with Boron Trifluoride-Amine Complexes or Tetrafluoroborate-Amine Salts

Abstract

The curing of epoxy resins with boron trifluoride-amine complexes (BFs-AC) or tetrafluoroborate-amine salts (BF, -AS) was studied by means of DTA.
The DTA thermogram showed, two exothermic peaks for BF, -AC and one peak for BF, -AS. The temperature Of the peak of higher temperature side for BF8-AC was almost the same as that of the peak for BF, -AS.
On the basis of the analysis made by IR and nitron-acetate methods, BF, -AC was found to react with equimolecular amounts of epoxy group, giving BF, -AS at the temperature of the peak of lower temperature side.
From these results, we suggest that BF3-AC reacts with epoxy resin in the BF3-AC-epoxy resin system to produce BF, -AS before curing, and the "true catalyst" of the curing for both 13F3-AC and BF, -AS systems would be the hydrogen atom located on the amine nitrogen in BF, -AS.