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1. (WO1998050828) PROCESS FOR MAKING PARTICULATE COMPOSITIONS

Pub. No.:    WO/1998/050828    International Application No.:    PCT/GB1998/000964
Publication Date: Fri Nov 13 00:59:59 CET 1998 International Filing Date: Thu Apr 02 01:59:59 CEST 1998
IPC: C08J 3/215
G03G 9/08
Applicants: AVECIA LIMITED
BEDELLS, Alison, Dawn
EDWARDS, Martin, Russell
MORRIS, Daniel, Patrick
ABHINAVA, Kumar
WOOD, William, Malcolm, Logan
Inventors: BEDELLS, Alison, Dawn
EDWARDS, Martin, Russell
MORRIS, Daniel, Patrick
ABHINAVA, Kumar
WOOD, William, Malcolm, Logan
Title: PROCESS FOR MAKING PARTICULATE COMPOSITIONS
Abstract:
There is described a process for producing a particulate composition comprising the steps of: (a) forming a first dispersion comprising first particles stabilised in a first fluid by a first species in an initial state, the first species changeable between the initial state and a further state, where the initial state provides (directly or indirectly) more stability to the particles within the dispersion than the further state; (b) optionally the step of forming a second dispersion comprising second particles stabilised in a second fluid, miscible with the first fluid, by a second species in the, or another, initial state, the second species also changeable between the, or another, initial state and the, or another, further state, where said initial state provides (directly or indirectly) more stability to the particles within the dispersion than said further state; (c) after the optional step of mixing the first and second dispersions together if the second dispersion was formed in step (b), changing the state(s) of the first and/or optionally second species from the initial state(s) to the further state(s) substantially to induce association between the dispersed particles to form clusters; and (d) binding together the particles within the clusters. A preferred embodiment of the process comprises mixing together two aqueous dispersions of particles (e.g. pigment particles with particles of latex polymer formed by emulsion polymerisation). The dispersions are stabilised by ionic surfactants of same sign charge. Association of the particles into clusters is induced by adjusting pH to selectively protonate or deprotonate the surfactants. The clusters are grown by aggregation into loose matrices which are fused together to form particles which can be used in electroreprographic toners.