Heat-sensitive record material and microcapsule

Abstract From the Canadian patent

The invention describes a heat-sensitive record system employing capsules formed of excess polyisocyanate compared to the stoichiometric quantity needed for encapsulation. The microcapsules comprise an integral outer wall material and an open-pore sponge-like networked core extending from the wall material into the microcapsule and defined by a plurality of substantially discrete but extensively interconnected void spaces a core material filling, said void spaces said microcapsule being a reaction product of an excess, compared to a stoichiometric amount for effecting encapsulation, of a polyisocyanate having a functionality greater than two with an active hydrogen-containing compound said, …