Curable cycloaliphatic epoxy-polyimide compositions

Claim 1

A low temperature curable composition comprising: (a) at least one curable polyimide prepolymer formed at a temperature sufficient to cause thermal reaction between heated components of a mixture of: (i) at least one aliphatic bismaleimide of the formula: ##STR36## wherein Z is a polyaliphatic ether in which each aliphatic group individually contains from one to about six carbon atoms, and in which each R is independently selected from the group consisting of hydrogen, an aliphatic group containing one or two carbon atoms, a benzenoid radical and a halogen; (ii) at least one aromatic polyamine; (iii) at least one aromatic bismaleimide of the formula: ##STR37## wherein each R is independently selected from a group consisting of hydrogen, an aliphatic group containing one or two carbon atoms, a benzenoid radical and a halogen and wherein R' is a bifunctional benzenoid radical selected from the group consisting of: ##STR38## wherein X is selected from the group consisting of: --O--, --S--, --SO 2 --, --CH 2 --, C 2 H 4 --, --CO--, --C 3 H 6 --, and ##STR39## and; (b) at least one cycloaliphatic epoxy resin having melting point less than about 120° F., containing at least two functional epoxy groups and selected from the group consisting of: (i) epoxy resins containing one cycloaliphatic ring formed of from 4 to about 8 carbon atoms in which each epoxy group is independently part of the ring or coupled to the ring by the structure: ##STR40## wherein Y is selected from the group consisting of --CH 2 --, --CH 2 CH 2 O--, ##STR41## --O--, --NH--, and --S-- and m is from 0 to about 20; (ii) epoxy resins containing two fused cycloaliphatic rings each cycloaliphatic ring independently containing from 4 to about 8 carbon atoms and in which each epoxy group is independently part of a ring or coupled to a ring by the structure: ##STR42## wherein Y is selected from the group consisting of --CH 2 --, --CH 2 O--, ##STR43## --O--, --NH--, and --S-- and m is from 0 to about 20, and (iii) epoxy resins containing two bridged cycloaliphatic rings, each cycloaliphatic ring independently containing from 4 to about 8 carbon atoms and coupled by a carbon-carbon bond or a group selected from --O--, --CH 2 --, --S-- and ##STR44## and in which each epoxy group is independently part of a ring or coupled to a ring by the structure: ##STR45## wherein Y is selected from the group consisting of --CH 2 --, --CH 2 O--, --CH 2 CH 2 O--, ##STR46## --O--, --NH--, --S-- and m is from 0 to about 20.