A process for the manufacture of chemically produced toner - 1. Evolution of structure and rheology

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A process for the manufacture of chemically produced toner (CPT) has been analyzed using model materials. In part 1 of this two-part paper, the impact of pH and temperature in a Couette-type rheometer and in a combination of two mechanically agitated systems with recirculation between them is reported. The initially stable 100 nm latex suspension at pH approximate to 9 was destabilized by the addition of acid accompanied by vigorous agitation. This destabilization led to the formation of primary aggregates of the original latex suspension of similar to 1-2 mu m which, at pH <4, themselves aggregated to give a closely packed paste or gellike structure. This rheologically complex structure had a Yield stress and exhibited internal slippage between primary aggregates at certain shearing conditions. The gel was broken by heating to above T-g, the glass-transition temperature, leading to the reformation of aggregates of the primary 1-2 mu m latex aggregates of similar to 6-12 mu m, which could be stabilized by raising the pH again to similar to 7. The final near-spherical model CPT product was obtained by heating the 6-12 mu m aggregates to >> T-g to cause internal coalescence. These changes of rheological property and structure and the physicochemical reasons for them are reported in detail.


Original languageEnglish
Pages (from-to)6004-1012
JournalIndustrial & Engineering Chemistry Research
Issue number16
Publication statusPublished - 3 Aug 2005