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Multi-functional Lewis Acid: Amine Curing Agents

IP.com Disclosure Number: IPCOM000122450D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 111K

Publishing Venue

IBM

Related People

Kuczynski, JP: AUTHOR

Abstract

This article describes a method for preparing thermally latent, multi- functional Lewis acid:amine complexes for use as thermally latent catalysts for epoxy curing.

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This is the abbreviated version, containing approximately 52% of the total text.

Multi-functional Lewis Acid: Amine Curing Agents

      This article describes a method for preparing thermally
latent, multi- functional Lewis acid:amine complexes for use as
thermally latent catalysts for epoxy curing.

      Epoxy resins have enjoyed considerable technical attention due
to their numerous attractive properties, including excellent adhesion
and chemical resistance.  Of the various techniques for crosslinking
epoxies, a great deal of effort has been focused on room temperature
polyaddition reactions with polyamines or aminic products, or
cationic initiation via Lewis acid:amine complexes [1].
Unfortunately, the resultant crosslinked networks tend to be somewhat
brittle (high modulus of elasticity).  Attempts to decrease the
elasticity modulus via external addition of a plasticizer generally
results in a degradation of mechanical properties.  An alternative
method involves internal plasticization by means of co-curing
urethane elastomers with epoxy resins, as illustrated in the drawing
[2]. Urethane polymers readily react at room temperature with the
polyamines routinely used to cure epoxies.  By judiciously balancing
the epoxy:urethane ratio, flexibilized urethane-urea modified epoxies
result.  The drawback to this approach is the room temperature
reactivity of epoxy and urethane resins, resulting in a poor shelf
life formulation and necessitating a two-component system.  From an
end-user perspective, it is desirable for the material to exhibit an
indefinite pot life at ambient temperatures, yet react readily at
elevated temperatures.  This is precisely the concept behind the
commercially available Lewis acid:monofunctional amine complexes.
However, proper network formation in cured epoxies, or urethane-urea
modified epoxies, cannot be achieved with monofunctional amines.  To
overcome this problem, multifunctional amine adducts of Lewis acids
were prepared.

      In the general synthetic procedure a molar excess of the Lewis
acid (as neat liquid, gas or ether or alcohol complex) is added
dropwise to a stirred solution of the multifunctional amine in a
suitable solvent.  Due to the magni...