Carrier coating and processes

A process for the preparation of conductive, electronegative, submicron polymeric particles consisting essentially of a first polymer selected in an amount of from about 1 to about 99 weight percent containing from about 1 to about 50 percent by weight of a conductive filler and a second electronegative, contrast polymer, and wherein said conductive polymer particles with filler are prepared by mixing at least one monomer with a polymerization initiator, a crosslinking component and a chain transfer component;

• effecting bulk polymerization at a temperature of from about 45.degree. C. to about 120.degree. C. until from about 5 to about 50 weight percent of the monomer has been polymerized;
• terminating polymerization by cooling the partially polymerized monomer;
• adding thereto from about 1 to about 50 weight percent of a conductive filler, followed by mixing thereof;
• dispersing the resulting mixture of conductive filler, and partially polymerized product in water containing a stabilizing component to obtain a suspension of particles with an average diameter of from about 0.05 to about 1 micron in water;
• polymerizing the resulting suspension at a temperature of from about 45.degree. to about 120.degree. C. by heating;
• adding a second contrast polymer emulsion in an amount of from about 1 to about 99 weight percent with high shear mixing;
• and subsequently washing and drying the polymer particles obtained.

A process for preparation of conductive, electronegative, submicron polymeric particles, subsequently used in the preparation of carrier particles, and wherein said submicron polymeric particles are comprised of a first polymer containing from about 1 to about 50 percent by weight of a conductive filler and a second electronegative, contrast polymer, and wherein said conductive polymer particles with filler is prepared by mixing at least one monomer with a polymerization initiator, a crosslinking component and a chain transfer component;

• effecting bulk polymerization until from about 5 to about 50 weight percent of the monomer has been polymerized;
• terminating polymerization by cooling the partially polymerized monomer;
• adding thereto from about 1 to about 50 weight percent of a conductive filler, followed by mixing thereof;
• dispersing the resulting mixture of said conductive filler, and partially polymerized product in water containing a stabilizing component to obtain a suspension of particles with an average diameter of from about 0.05 to about 1 micron in water;
• polymerizing the resulting suspension by heating;
• adding a second contrast polymer emulsion, suspension or fine dispersion with a high shear mixer;
• subsequently washing and drying the product;
• thereafter heating a carrier core or carrier cores and the resulting conductive polymer particle blend to enable fusing thereof to said core or cores;
• and cooling the carrier particles obtained, which carrier particles have a conductivity of from between about 10.sup.-4 to about 10.sup.-10 (mho-cm.sup.-1).