Particulate polymer, electrophotographic toner, and preparation method

摘要

A method for making a polymeric particulate, polymeric electrophotographic toner and the particulate and toner. In the method a reaction mixture is prepared that includes vinyl type monomer, crosslinker, and chain transfer agent. The crosslinker has a concentration greater than 0.4 parts by weight per 100 parts by weight of the monomer. The crosslinker and the chain transfer agent together have a combined concentration of greater than 0.6 parts by weight per hundred parts of the monomer. The reaction mixture is subjected to addition polymerization conditions favoring formation of polymer including a first portion having a molecular weight in excess of 1 x 10<6> and a second, tetrahydrofuran soluble portion having a molecular weight distribution determined by molecular exclusion chromatography including a first peak centered in the molecular weight range of from 0.8 x 10<4> to 1 x 10<5>. The polymer is melt processed resulting in a melt product, which is then pulverizing to a volume average particle size of from 5 to 20 micrometers to produce particulate. The particulate includes polymer having a molecular weight distribution determined by molecular exclusion chromatography substantially retaining the first peak and including a second peak in the molecular weight range of from 1 x 10<5> to 1 x 10<7>.