Treatment of electrophotographic toner compositions

Method for separating mineral spirit solvent vehicle constituents from charge-responsive colorant constituents in electrophotographic quality, normally liquid hydrocarbon mineral spirit-based toner compositions containing said charge responsive colorant constituents, which are resin binder coated colorant materials, dispersed in the solvent vehicle, said charge response colorant constituents being responsive to attraction by electrical charge so as to deposit on a sensitized and exposed latent image retaining electroconductive base material whereby the image is fixed and developed in the base, which method comprises the steps of:

• i. uniformly dispersing said toner in water to form a dispersion;
• ii. introducing generally onto the surface of said dispersion, without substantial physical intermixing, a quantity of an extractant mixture comprising a normally liquid hydrocarbon mineral spirit which contains between about 1.0 to about 10.0 wt. % of a conventional charge control agent of the type utilized in liquid toners;
• iii. contacting said quantity of an extractant mixture, without substantial intermixing, with said dispersion for a time sufficient for at least a portion of the charge-responsive colorant constituent in the toner to be attracted to said quantity of an extractant mixture by substantially agglomerating and clustering in close physical proximity thereabout at the interface of the water and dispersed solvent and extractant liquid, thereby forming a colorant constituent agglomeration;
• iv. physically separating said colorant constituent agglomeration and extractant mixture associated therewith from that which remains of said dispersion.