Latent hardener with improved barrier properties and compatibility
A curing agent for epoxy resins that is comprised of the reaction product of an amine, an epoxy resin, and an elastomer-epoxy adduct; compositions containing the curing agent and an epoxy resin; the compositions are useful in electronic displays, circuit boards, semi conductor devices, flip chips and other applications.
1. A curing agent for epoxy resins that is comprised of the reaction product of:
(a) an amine, and
(b) an epoxy resin, and
(c) an elastomer-epoxy adduct
wherein the elastomer-epoxy adduct is a carboxyl-terminated butadiene-acrylonitrile (CTBN)-epoxy adduct which functions as a dispersant; wherein the amine is reacted with the dispersant followed by the epoxy resin to produce a dispersion of epoxy resin particles; wherein the particles are encapsulated in a polymer shell that is the reaction product of a multifunctional isocyanate and a multifunctional epoxy compound.
2. The curing agent of claim 1 wherein the nitrile content of the CTBN is about 12-35% by weight.
3. The curing agent of claim 2 wherein the nitrile content is about 20-33% by weight.