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 compound, and
(b) an epoxy resin, and
(c) an elastomer-epoxy adduct wherein the amine compound and the epoxy resin are reacted in the presence of the adduct, as a reactive dispersant, in an amount of about 5 to 50% (w/w) of the adduct based on the combined weights of the reactive dispersant and the amine compound to produce a dispersion of epoxy resin particles; wherein the particles are encapsulated in a polymer shell.
2. The curing agent of claim 1 wherein the curing agent comprises the reaction product of:
(a) an amine compound, and
(b) an epoxy resin, and
(c) a carboxyl-terminated butadiene-acrylonitrile (CTBN)-epoxy adduct.
3. The curing agent of claim 2 wherein the nitrile content of the CTBN is about 12-35% by weight.
4. The curing agent of claim 3 wherein the nitrile content is about 20-33% by weight.
5. The curing agent of claim 2 wherein the curing agent is formed as the core phase of a dispersion and the particles are encapsulated in a polymer shell.
6. The curing agent claim of 5 wherein two or more polymer shells are formed in a step-wise fashion by reacting the particles with a multi-functional isocyanate.
7. The curing agent of claim 5 wherein additionally two or more polymer shells are formed in a step-wise fashion by reacting the particles with a multifunctional isocyanate and a multifunctional epoxy compound.
8. The curing agent of claim 5 wherein additionally two or more polymer shells are formed in a step-wise fashion by reacting the particles with a multifunctional isocyanate and a multifunctional epoxy compatible compound.
9. The curing agent of claim 5 wherein additionally two or more polymer shells are formed in a step-wise fashion by reacting the particles with a multifunctional isocyanate, a multifunctional epoxy compound, and epoxy compatible compound.