| 摘要 |
PURPOSE:To obtain a carrier which is stable and is negatively electrostatically charged by incorporating styrene more in the carrier of a developing agent consisting of a magnetic carrier contg. carbon black having specific pH or above and styrene polymer and a toner cong. a styrene-acryl copolymer and a coloring agent. CONSTITUTION:A developer wherein % of the styrene monomer in the carrier is larger by >=10% than % of the styrene monomer in the toner is prepd. of a developer consisting of the magnetic carrier which is a copolymer resin of 60wt% a styrene monomer and a monomer, such as (meth)acrylate, acrylonitrile or the like, and has 5,000-200,000 average Mw., 2,000-1000,000 average Mn, and 10- 40mu average grain size and contains magnetic powder and carbon black having >=5 pH as well as a toner which contains a copolymer resin of 20-80wt% styrene monomer and (meth)acrylate monomer and a coloring agent (pigment or dye) and has 5,000-20,000 average Mn, 30,000-500,000 average Mw. and 40- 70 deg.C glass transition temp. |
