Abstract: A toner suitable for use in an image forming method including a contact charging step is provided. The toner includes: toner particles comprising at least a binder resin and a colorant, and fine particles. The fine particles comprise: (i) a tungsten-containing tin oxide, or (ii) base particles, and a tungsten-containing tin compound coating the base particles, the fine particles contain tin (Sn) in a weight ratio (Sn/b) of 0.01 to 2.0 with respect to the base particles (B). In the fine particles, tungsten (W) is contained in a mol ratio (W/Sn) of 0.001 to 0.3 with respect to the tin (Sn).

Abstract: A toner suitable for use in an image forming method including a contact charging step is provided. The toner includes: toner particles comprising at least a binder resin and a colorant, and fine particles. The fine particles comprise: (i) a tungsten-containing tin oxide, or (ii) base particles, and a tungsten-containing tin compound coating the base particles, the fine particles contain tin (Sn) in a weight ratio (Sn/b) of 0.01 to 2.0 with respect to the base particles (B). In the fine particles, tungsten (W) is contained in a mol ratio (W/Sn) of 0.001 to 0.3 with respect to the tin (Sn).

Abstract: Magnetic particles for charging an image-bearing member electrostatically. The charging magnetic particles have magnetic particles, first surface coat layers containing a first surface coating agent and covering the surfaces of the magnetic particles and second surface coat layers containing a second surface coating agent and covering the first surface coat layers. The charging magnetic particles contain magnetic particles for charging which have a maximum chord length of 5 &mgr;m or larger, and the magnetic particles for charging which have a maximum chord length of 5 &mgr;m or larger having a minor-axis length/major-axis length standard deviation of 0.08 or more. Also, a process for producing the charging magnetic particles is disclosed together with a charging member, a process cartridge and an image forming apparatus which make use of the charging magnetic particles.

Abstract: An electrophotographic apparatus includes an electrophotographic photosensitive member, and (i) a charger, (ii) an imagewise exposure device, (iii) a developing device and (iv) a transfer device, disposed in this order opposite to the photosensitive member. The charger includes a charging member including magnetic particles disposed in contact with the photosensitive member so as to charge the photosensitive member based on a voltage received thereby. The magnetic particles are surface-coated with a coupling agent having a linear alkyl group having a least 6 carbon atoms. The developing device also functions to recover residual toner remaining on the photosensitive member processing by the transfer device and the charger. Because of the coating with such a specific coupling agent, the charging magnetic particles can exhibit good triboelectric changeability for the transfer residual toner for a long period.

Abstract: A magnetic particle for charging is disclosed. The magnetic particle includes magnetic particles having particle diameters of 5 .mu.m or more. The magnetic particles having particle diameters of 5 .mu.m or more have a standard deviation of short-axis length/long-axis length of 0.08 or more, and a volume resistance value in the range of 10.sup.4 to 10.sup.9 .OMEGA.cm. Also, provided are a charging member, a charging device, a process cartridge and an electrophotographic apparatus, using the magnetic particle.

Abstract: An electrophotographic apparatus includes: an electrophotographic photosensitive member, a charging device including a charging member formed of magnetic particles and disposed contactable to the photosensitive member so as to charge the photosensitive member based on a voltage applied thereto, exposure device, developing device, and a transfer device. The magnetic particles exhibit a good charging ability for a long period and therefore provide a good continuous image-forming performance because they are formed of ferrite particles including a ferrite having a very limited composition represented by the formula of:(MnO).sub.x (MgO).sub.y (Fe.sub.2 O.sub.3).sub.z,wherein x, y and z are numbers satisfying x+y+z.ltoreq.1, 0.2<x<0.5, 0.05<y<0.25 and 0.4<z<0.6, and 0.01-3 wt. parts of phosphorus added per 100 wt. parts of the ferrite and contained preferentially at a larger concentration at the surfaces of the magnetic particles than in the entirety of the magnetic particles.

Abstract: A charging apparatus which comprises an electrophotographic photosensitive member and a charging member which comprises magnetic particles and placed in contact with the electrophotographic photosensitive member to charge the electrophotographic photosensitive member upon application of a voltage, wherein each magnetic particle has a surface layer containing a polyolefin resin of which weight average molecular weight is 10,000 or more, and has a volume resistivity of 1.times.10.sup.4 to 1.times.10.sup.11 .OMEGA.cm.

Abstract: A charging member, which electrically charges an object to be charged by being placed in contact with the object to be charged and by being applied with a voltage, is provided where the charging member includes an electroconductive base and brush bristles to come into contact with the object to be charged, and the brush bristles include at least one of etching fibers and divided fibers.

Abstract: A charging member includes a conductive substrate and a surface layer which is to be brought into contact with a member to be charged. On the surface layer a raised fiber entangled material is provided.

Abstract: A charging member suitable for charging, e.g., a photosensitive member for electrophotography, is provided with improve surface-properties. The charging member is surface with a resin formed by plasticizing a rigid polymer with a plasticizing polymer chemically bonded to the rigid polymer.

Abstract: A charging apparatus or an electrophotographic apparatus includes an electrophotographic photosensitive member including a photosensitive layer provided on a conductive supporting member, and a charging member including magnetic particles, disposed to be in contact with the electrophotographic photosensitive member, for charging the electrophotographic photosensitive member when a voltage is applied to the charging member. The layer of the electrophotographic photosensitive member most separated from the conductive supporting member has a volume resistivity between 10.sup.8 .OMEGA..cm and 10.sup.15 .OMEGA..cm, and the magnetic particles have a hygroscopic property such that the ratio H/L of the maximum value H to the minimum value L of the amount of water contained within the particles is at least 1 and less than 4.

Abstract: A charging member for charging a charge-receiving member, such as an electrophotographic photosensitive member, by disposing the charging member in contact with the charge-receiving member and applying a voltage to the charging member is constituted by disposing an electroconductive support, an elastic layer, and a surface coating layer having a tensile modulus of above 2000 kgf/cm.sup.2 to at most 30000 kgf/cm.sup.2 in this order. The coating layer may preferably contain an acrylic polymer-modified urethane resin. The charging member is effective in providing the charge-receiving member with a nip portion showing a uniform electric resistance distribution for a long period to provide excellent images.

Abstract: A charging member contactable to a member to be charged to electrically charge it, the improvement residing in that a microhardness of an end region, with respect to a longitudinal direction, of the charging member is larger than that in a central region of the charging member.

Abstract: A toner for developing an electrostatic image is composed by a binder resin, and a magnetic material and/or a colorant. The binder resin (a) comprises a styrene resin polymerized in the presence of a poly-functional polymerization initiator, (b) provides a molecular weight distribution on a GPC chromatogram showing a maximum (P1) in a molecular weight range of 3.5.times.10.sup.3 -5.times.10.sup.4 and a maximum (P2) or shoulder in a molecular weight range of at least 1.times.10.sup.5, and (c) contains 15 wt. % or less of a resin component in a molecular weight range of at most 3.times.10.sup.3. Further the toner contains at most 100 ppm of styrene and benzaldehyde.

Abstract: The present invention relates to an electrophotographic image forming method characterized in using a photosensitive member having an organic photoconductive layer and fluorine-containing resin particles in the surface, a contact charging means being in contact with the photosensitive member to electrostatically charge it, a contact transfer means being in contact with the photosensitive member to transfer the developed image to the transfer medium;wherein the toner to be used for developing the latent image is a magnetic toner comprising at least a magnetic material and a binder resin, wherein the binder resin contains a polymer synthesized from vinyl monomer in the presence of an aromatic organic solvent in an amount of 50 parts by weight or more on the basis of 100 parts of the binder resin, and the amount of the residual aromatic organic solvent in the magnetic toner is 500 ppm by weight or less.

Abstract: A process for producing a toner comprises the steps of mixing toner particles having a weight average particle diameter of from 2 to 15 .mu.m, with an external additive to prepare a toner, and passing the resulting toner through a sieve. The sieve has a wire cloth of twill weave that satisfies the following condition:0.052.ltoreq.d mm .ltoreq.0.208100.ltoreq.W .mu.m .ltoreq.1807.3.times.10.sup.-4 .ltoreq.d mm / W .mu.m.ltoreq.9.1.times.10.sup.-4wherein d represents average diameter of the wire used in the sieve, and W represents an aperture size of the sieve.

Abstract: The present invention provides a developer which is comprised of the magnetic toner having the specific binder resin component and low-molecular weight wax and the additives of the fine silica powder, metal oxide powder and fluorine-containing fine resin powder which are used in combination in given amounts. Hence, it is possible to prevent the melt-adhesion of toner to the surfaces of the contact charging member and contact transfer member, to cause no faulty images and to obtain images with the enjoyment of superior low-temperature fixing performance and anti-offset properties, even when copies are taken on a large number of sheets using the image forming method having contact charging and contact transfer systems.