PURPOSE: To obtain a good picture quality excellent in heat stability preventive of generating heat fogging to a copied material even after keeping in a state of elevated temp. for a long term by surface treating a toner with a specific polymethylmethacrylate powder and granular material.
CONSTITUTION: When the toner using a low melting point resin as a binder is used, a polymethyl methacrylate(PMMA) power and granular material having smaller average particle diameter than that of the toner particle and charge positive to a carrier constituting a developer is externally added to the surface of the toner by surface treating. As the surface treating, after the toner is obtained by executing necessary processes such as kneading, pulverizing classifying or the like, a desired quantity of PMMA is added the toner together with an external-additive such as a silica particulate and is putted into an agitating mixer to surface treat by externally adding and the product toner is obtained. As a result, rising of charged quantity in a developing vessel is accelerated and also charge saturation value becomes high.
NAKAMURA MASA
NAKANO NOBUHIKO
OKAMOTO KANJIROU
OUCHI TAKEAKI
MURAKAMI TOSHIHIKO
