Patent ID: 6987161

Claim:
A method of designing a hardener for an epoxy resin to produce a hardened epoxy resin having good mechanical and thermal properties by curing under pre-determined cure temperature and time conditions, the method comprising the steps of: a) selecting a component from the group consisting of a mixture of polyamines and tertiary amines, imidazole, and dicyandiamide; b) selecting a polyol mixture comprising a first polyol having phenolic hydroxy groups, secondary hydroxy groups, and combinations thereof, and a second polyol having methylol functional groups, secondary hydroxy groups and combinations thereof, or only the combination of methylol functional groups and secondary hydroxy groups; c) forming the hardener by combining the component and the polyol; d) combining the hardener with the epoxy resin to form an epoxy-hardener system; e) curing the epoxy-hardener system at a pre-determined cure temperature and time; f) determining whether a glass transition temperature of the epoxy-hardener system is approximately equal to the pre-determined cure temperature plus 45° C. as represented by the equation T g ≈T c +45° C.; g) determining whether the ultimate glass transition temperature is approximately equal to the glass transition temperature as represented by the equation T gu ≈T g ; and h) accepting the hardener if the equations in both steps f and g) are satisfied, or otherwise reformulating the hardener until both steps f) and g) are satisfied.