Encapsulated toner for heat-and-pressure fixing

Abstract

An encapsulated toner for heat-and-pressure fixing having excellent offset resistance and blocking resistance, being fixed at a low fixing temperature and being regulated with the charging properties thereof from the inside of the encapsulated toner to stably and repeatedly form a scum-free, clear image many times, comprised of a heat-fusible core containing at least a coloring material, a binder and an electric charge control agent selected from the group consisting of a positive electric charge control agent, a negative electric charge control agent and a mixture thereof at a weight ratio of one to the other ranging from 1:0 (exclusive) to 1:0.5, and a shell formed so as to cover the surface of the core, wherein the main component of the shell is a resin prepared by reacting (A) an iso(thio)cyanate compound comprising (1) 0 to 30 mole % of monovalent isocyanate and/or isothiocyanate compounds, and (2) 100 to 70 mole % of at least divalent isocyanate and/or isothiocyanate compounds, with (B) an active hydrogen compound comprising (3) 0 to 30 mole % of a compound having one active hydrogen atom reactive with isocyanate and/or isothiocyanate groups, and (4) 100 to 70 mole % of a compound having at least two active hydrogen atoms reactive with isocyanate and/or isothiocyanate groups, at a molar ratio of component (A) to component (B) of between 1:1 and 1:20, and wherein at least 30% of all of the linkages in which an isocyanate and/or isothiocyanate group participates are thermally dissociable linkages.

Dependencies are inferred from the claim text.