Boron trifluoride monoethylamine

The two most common BF3 amine catalysts used commercially to cure epoxies are boron trifluoride monoethylamine, BF3 NH2C2H5, and boron trifluoride piperidine, BF3 NHCsHi0, complexes. Such complexes are latent catalysts at room temperature but enhance epoxide group reactivity at higher temperatures. 

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,... 

It easily forms double compds, such as boron trifluoride etherate. Another compd, boron trifluoride-monoethylamine, BF3— C2H5NH2 is wh to pale tan flakes, melting at 88—90°. It released BF3 above 110° and is used for elevated temp cure of epoxy resins Refs 1) Gmelin-Kraut Syst Number 13(1954), 168 2) CondChemDict (1961), 166-tL R ... 

Previous Work on Latent Catalysts for Epoxy Resins. Numerous patents (, , ) have been issued in recent years on the development of latent catalysts for DGEBA (i.e., diglycidylether of bisphenol a ) resins, but most fulfill only a few of the conditions outlined above. One of the most successful of these has been the boron trifluoride-monoethylamine complex ( ). However, one of the serious disadvantages of this particular latent catalyst is the poor electrical properties at elevated temperatures of the epoxy resin in the cured state (7 ). 

Resin III is based upon DGEBA and an epoxy novolac in a one-to-two weight ratio. The curing agent is 3 percent boron trifluoride monoethylamine complex. The supplier s recommend cure cycle is 0.75 hour at 165 C followed by 4 hours post cure at 177 C. Some samples were cured for 24 hours at 80°C before post cure, while other samples were cured for the standard 0.75 hour at 165 C and subjected to different post cure times (2). There is still residual epoxide absorbance following initiaT 165°C cure. This absorbance decreases during post cure reaching zero after 4 hours. 

Boron trifluoride-monoethylamine. See Boron trifluoride-ethylamine... 

Lewis Acids. Lewis acids, eg, boron trihalides, contain an empty outer orbital and therefore seek reaction with areas of high electron density. Boron trifluoride, BF3, a corrosive gas, reacts easily with epoxy resins, causing gelation within a few minutes. Complexation of boron trihalides with amines enhances the curing action. Reasonable pot lives using these complexes can be achieved because elevated temperatures are required for cure. Reactivity is controlled by the choices of the halide and the amine. The amine choice also affects other properties such as solubility in resin and moisture-sensitivity. Boron trifluoride monoethylamine (BF3 NH2C2H5), a crystalline material which is a commonly used catalyst, cures epoxy resins at 80-100°C. A chloride version is also commercially available. Other Lewis acids used in epoxy curing include stannic chloride and tin octanate. 

Figure 3.5 Thermogravimetric curves with boron trifluoride monoethylamine (BF3MEA) as curing agent. Reproduced with permission from J.A. Bremner, Industrial Engineering Chemistry Product Research and Development, 1964, 3, 1,...

Boron trifluoride monoethylamine Butylated hydroxy toluene Bismaleimide... 

The amount of catalyst used may vary from 2 to 10 parts per 100 parts resin. To determine the best ratio of catalyst to resin, several different catalyst levels should be evaluated to determine which level provides maximum properties. Several common catalytic curing agents are benzyldimethylamine (BDMA), boron trifluoride monoethylamine (BF3 MEA), and 2-methylimidazole (2-MI). 

Boron trifluoride hardeners Boron trifluoride monoethylamine melts at 95 °C and is used in one-part adhesives... 

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