Abstract
New epoxy resin laminates were developed, which showed high heat resistance including partly oxazolidone rings by a reaction of epoxy groups and isocyanate groups.
These laminates are prepared by using a prepolymer stable at room temperature which was obtained through the reaction of isocyanate groups with hydroxy groups of epoxy resins.
When this prepolymer is used with amine compounds as curing agent for a varnish for laminates, reaction between amino groups and epoxy groups occurs accompanied with oxazolidone ring formation, and an epoxy laminate (CL-I) with high heat resistance can be obtained.
Further, when formulating bisimide compounds in the above varnish of the prepolymer, a laminate (CL- n) with much higher heat resistance can be obtained.
