Cyanourea compounds or polymers thereof as epoxy resin curing agents

A heat curable composition comprising

• (1) an epoxy resin, and
• (2)a polymer having the following recurring structural units:
• ##STR13## wherein R is the organic moiety of a polyisocyanate remaining after reaction of the isocyanate groups to form cyanourea groups and m is at least 2, the equivalent ratio of epoxide:N-cyanourea being 1 to 30:2.

A process for forming a thermoset material which comprises heating an epoxy resin and a cyanourea compound of the formula:

• ##STR14## wherein R is the organic moiety of a mono- or polyisocyanate remaining after reaction of the isocyanate groups to form cyanourea groups and n is 1 or more at a temperature above 100.degree. C., the equivalent ratio of epoxide:N-cyanourea being 1 to 30:2.

A process for forming a thermoset material which comprises heating an epoxy resin and a polymer having the following recurring structural units:

• ##STR15## wherein R is the organic moiety of a polyisocyanate remaining after reaction of the isocyanate groups to form cyanourea groups and m is at least 2 at a temperature above 100.degree. C., the equivalent ratio of epoxide:N-cyanourea being 1 to 30:2.

The process of adhering two substrates which comprises applying to at least one of said substrates a heat curable composition comprising an epoxy resin and a cyanourea compound of the formula:

• ##STR16## wherein R is the organic moiety of a mono- or polyisocyanate remaining after reaction of the isocyanate groups to form cyanourea groups and n is 1 or more, the equivalent ratio of epoxide:N-cyanourea being 1 to 30:2 contacting the substrates with the composition therebetween and heating the thus contacted substrates at a temperature above 100.degree. C.

The process of adhering two substrates which comprises applying to at least one of said substrates a heat curable composition comprising

• (1) an epoxy resin, and
• (2) a polymer having the following recurring structural units:
• ##STR17## wherein R is the organic moiety of a polyisocyanate remaining after reaction of the isocyanate groups to form cyanourea groups and m is at least 2, the equivalent ratio of epoxide:N-cyanourea being 1 to 30:2 contacting the substrates with the composition therebetween and heating the thus contacted substrates at a temperature above 100.degree. C.