Patent ID: 7811738
Filing Date: 2010-10-12
Classification: G03G

Abstract:
1. An image forming method comprising the following steps 1 to 6: (1) a charging step 1 of charging the surface of a photosensitive member having a layer structure that a photosensitive layer is arranged on an electrically conductive base; (2) an exposure step 2 of exposing the charged surface of the photosensitive member to a patterned light to form an electrostatic latent image; (3) a development step 3 of developing the electrostatic latent image on the surface of the photosensitive member in contact with a toner supplied on a developing roll to form a toner image; (4) a transfer step 4 of transferring the toner image on the surface of the photosensitive member to a transfer material; (5) a fixing step 5 of fixing the toner image transferred to the transfer material; and (6) a cleaning step 6 of removing the toner remaining on the surface of the photosensitive member after the transfer step by means of a cleaning blade brought into contact with the surface of the photosensitive member, wherein (a) the developing roll has a surface brightness from 60 to 140 and a surface roughness Rz from 3 to 8 μm, wherein the developing roll has a structure that the roll is equipped with a columnar electrically-conductive shaft and an elastic layer covering the surface of the electrically-conductive shaft, and a resin coating layer is further formed on the surface of the elastic layer, and wherein the columnar electrically-conductive shaft includes a metal core, (b) the cleaning blade is a cleaning blade made of a polyurethane elastomer and has a peak temperature of viscoelasticity tan δ from −15 to 10° C., a width at half maximum of viscoelasticity tan δ of at least 25° C., and a hardness in Japanese Industrial Standards from 60 to 90, wherein the polyurethane elastomer making up the cleaning blade is a polyester polyol type polyurethane elastomer, (c) the photosensitive member is a photosensitive drum having a diameter from 20 to 60 mm and a layer structure that an organic photoconductor layer (C) having a thickness from 15 to 100 μm is arranged on a cylindrical aluminum base (A) through a sublayer (B) composed of an alumite layer formed by an anodic oxidation treatment of the surface of the aluminum base or an undercoating layer formed by a resin composition containing an inorganic pigment and having a thickness from 5 to 50 μm, (d) the toner contains colored resin particles having a volume average particle diameter from 4 to 10 μm and an average circularity from 0.950 to 0.995 and an external additive, wherein the toner comprises 0.1 to 2 parts by weight, per 100 parts by weight of colored resin particles, of fine silica particles, the number average particle diameter of primary particles of which is 5 to 20 nm, and 0.5 to 2.5 parts by weight of spherical fine silica particles having a volume average particle diameter from 0.1 to 0.5 μm as external additives, and wherein the colored resin particles are those obtained by a polymerization process, (e) the charge level of the toner on the surface of the photosensitive member after the development is 10 to 45 μC/g in terms of an absolute value, and wherein the amount of the toner on the surface of the photosensitive member after the development is within a range from 0.3 to 0.8 mg/cm (f) the toner shows a pH from 3 to 8 as measured in the form of an extract obtained by a boiling treatment in ion-exchanged water having a pH of 7.