BF3-Monoethylamine

Boron trifluoride monoethylamine (BF3-MEA) is a Lewis acid catalyst. Lewis acids are electron pair acceptors that function as curing agents by coordinating with the epoxy oxygen, [Pg.104]

BF3-MEA is a complex that is formed between boron trifluoride gas and monoethy-lamine. It is a solid melting at close to its dissociation temperature (80 to 85°C). BF3-MEA shows hydroscopic tendencies. On exposure to moist air, it hydrolyzes into a viscous liquid that is unsuitable as a curing agent. [Pg.105]

The BF3-MEA must be melted and dissolved in liquid epoxy resins. For small batches, the procedure is to heat the resin to 85°C and stir in the curing agent. For larger batches, about 3 parts by weight of the catalyst is stirred into about 5 parts by weight of the resin preheated to 50°C. This produces a smooth paste, which then may be added to the remainder of the resin heated to 85°C. Alternatively, the BF3-MEA can be dissolved in a solvent such as furfural alcohol, which will also dissolve the epoxy resin. [Pg.105]

Although it is formed from a very reactive catalyst (BF3 gas), the monoethylamine blocks the reactions sufficiently that BF3-MEA can be considered to be a latent catalyst. It provides a pot life of 6 to 12 months at room temperature. It does not show significant curing activity until temperatures of 100 to 125°C have been reached. [Pg.105]

In most formulations, the concentration of BF3-MEA in DGEB A epoxy resins is on the order of 2 to 4 pph. Curing temperatures are usually 2 h at 105°C followed by a postcure at 150 to 200°C for 4 h for optimum properties. The rate of cure is very sensitive to temperature below 100°C the rate is negligible, and at 120°C it is very rapid and accompanied by a significant exotherm. [Pg.105]

Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...