Patent ID: 6531256
Filing Date: 2003-03-11
Classification: C08J,G03G

Abstract:
A process for producing a particulate composition comprising:(a) forming a first aqueous dispersion comprising pigmentary particles stabilised by a reversibly protonatable or deprotonatable first species, one of the protonated or deprotonated states of said first species providing more stability to the pigmentary particles than the other of said states; (b) forming a second aqueous dispersion miscible with the first aqueous dispersion and comprising polymer particles stabilised by a reversibly protonatable or deprotonatable second species, one of the protonated or deprotonated states of said second species providing more stability to the polymer particles than the other of said states; (c) mixing the first and second dispersions optionally under conditions where the net electric charge on the particles is not substantially mutually attractive, to obtain a substantially homogeneous mixture in the absence of substantial association; adjusting the pH of the mixture to alter the protonation state of the first and/or second species so the net electric charge on the first and second particles is not substantially mutually repulsive and association between the first and second particles to form clusters can be substantially induced; and inducing by heating growth of the clusters into dispersed matrices of loosely associated clusters; (d) heating the mixture from step (c) at a temperature above the glass transition temperature of the constituent polymers to fuse together the particles within the matrices; and (e) collecting the particles obtained from step (d) to produce, after optional washing, drying and/or blending with surface additives, an electroreprographically effective toner.