Abstract: An image forming apparatus includes a member to be charged for carrying an electrostatic latent image; a contact charging means for contact charging the member to be charged and a developing means for developing the latent image. The developing means includes a developer having a magnetic toner and fine powder treated with a silicone oil or varnish-treating agent, wherein the magnetic toner particles include a binder resin and contain from 10-70 wt. % of magnetic fine powder. An image forming method includes the steps of contact charging, latent image forming and developing with a developer having the binder resin, 10 to 70 wt. % magnetic fine powder and fine powder treated with a silicone oil or varnish-treating agent.

Abstract: An image forming apparatus includes a member to be charged for carrying an electrostatic image, a contact-charging means for charging the member to be charged in contact with the member to be charged, and a developing means for developing the electrostatic image carried on the member to be charged. The developing means includes a developer for developing the electrostatic image comprising a toner and hydrophobic inorganic fine powder. The hydrophobic fine powder has a hydrophobicity of 60% or higher and the toner has a volume average particle size of 4-8 microns. The hydrophobic inorganic fine powder not only improves the fluidity of the developer and adjusts the chargeability of the developer but also prevents difficulties due to interaction between the member to be charged and the contact charging means in the presence of residual developer, such as damages of the member to be charged and toner-sticking onto the member to be charged.

Abstract: An image forming method, including the steps of: developing an electrostatic image formed on an electrostatic image-bearing member with a developer to form thereon thereon a developed image, the developer containing 100 wt. parts of a toner and 0.05 to 3 wt. parts of fine powder treated with a silicone oil or silicone varnish; and transferring the developed image on the electrostatic image-bearing member to a transfer material while causing a transfer device, such as a roller or belt to contact the electrostatic image-bearing member by the medium of the transfer material under a line pressure of 3 g/cm or higher.

Abstract: An image forming method, including the steps of: developing an electrostatic image formed on an electrostatic image-bearing member with a developer to form thereon thereon a developed image, the developer containing 100 wt. parts of a toner and 0.05 to 3 wt. parts of fine powder treated with a silicone oil or silicone varnish; and transferring the developed image on the electrostatic image-bearing member to a transfer material while causing a transfer device, such as a roller or belt to contact the electrostatic image-bearing member by the medium of the transfer material under a line pressure of 3 g/cm or higher.

Abstract: The present invention provide a toner for developing an electrostatic image. The toner comprises a binder resin and a coloring agent. The binder resin comprises a styrene type binder resin. The amount of an aldehyde contained in the binder resin is not more than 0.005% by weight based on the weight of the toner. The binder resin is produced by a process comprising the steps of preparing a monomer composition comprising a polymerizable monomer containing at least not less than 50% by weight of a styrene monomer, and a polymerization initiator, and subjecting said monomer composition to suspension polymerization in an aqueous medium having dissolved oxygen in an amount of not more than 2.5 mg/lit to form a styrene polymer or copolymer containing an aldehyde monomer in an amount of not more than 0.01% by weight.

Abstract: An image forming apparatus includes a member to be charged for carrying an electrostatic image, a contact-charging means for charging the member to be charged in contact with the member to be charged, and a developing means for developing the electrostatic image carried on the member to be charged. The developing means includes a developer for developing the electrostatic image comprising a toner and hydrophobic inorganic fine powder. The hydrophobic inorganic fine powder not only improves the fluidity of the developer and adjusts the chargeability of the developer but also prevents difficulties due to interaction between the member to be charged and the contact charging means in the presence of residual developer, such as damages of the member to be charged and toner-sticking onto the member to be charged.

Abstract: An image forming method, including the steps of: developing an electrostatic image formed on an electrostatic image-bearing member with a developer to form thereon thereon a developed image, the developer containing 100 wt. parts of a toner and 0.05 to 3 wt. parts of fine powder treated with a silicone oil or silicone varnish; and transferring the developed image on the electrostatic image-bearing member to a transfer material while causing a transfer device, such as a roller or belt, to contact the electrostatic image-bearing member by the medium of the transfer material under a line pressure of 3 g/cm or higher.

Abstract: A magnetic developer for developing an electrostatic latent image, including hydrophobic silica fine powder and an insulating magnetic toner comprising at least a binder resin and a magnetic material comprising spherical magnetic particles; wherein 0.16 to 1.6 wt. parts of the hydrophobic silica fine powder is mixed with 100 wt. parts of the insulating magnetic toner; the developer contains 17-60% by number of magnetic toner particles having a particle size of 5 microns or smaller, 5-50% by number of magnetic toner particles having a particle size of 6.35-10.08 microns, and 2.0% by volume or less of magnetic toner particles having a particle size of 12.7 microns or larger.

Abstract: A developer for developing electrostatic latent images is constituted by a toner, and negatively chargeable spherical resin particles having an average particle size of 0.03-1.0 micron and a volume resistivity of 10.sup.6 -10.sup.12 ohm.cm. The toner may comprise toner particles and hydrophobic inorganic fine powder, which is generally used in a larger amount than the negatively chargeable spherical resin particles. The negatively chargeable spherical resin particles function to provide a toner image which is faithful to an electrostatic latent image formed on a photosensitive member while preventing toner-sticking onto the photosensitive member preferably in combination with a contact-charging means for charging the photosensitive member.

Abstract: An image forming apparatus has a charging device for charging a photosensitive member containing an organic photoconducter, an exposure device, a developing device including a developer, a transfer device and a cleaning device. The photosensitive member employs an organic photoconductor and a polycarbonate resin layer which forms the surface of the photosensitive member. The developer device has a sleeve with a thin layer of an electrical coating material containing dispersed carbon particles. The developer contains insulating magnetic toner particles of relatively small particle size formed from a styrene-acrylic type copolymer or a polyester resin and a magnetic powder.

Abstract: A developer for developing electrostatic latent images is constituted by a toner, and negatively chargeable spherical resin particles having an average particle size of 0.03-1.0 micron and a volume resistivity of 10.sup.6 -10.sup.12 ohm.cm. The toner may comprise toner particles and hydrophobic inorganic fine powder, which is generally used in a larger amount than the negatively charageable spherical resin particles. The negatively chargeable spherical resin particles function to provide a toner image which is faithful to an electrostatic latent image formed on a photosensitive member while preventing toner-sticking onto the photosensitive member preferably in combination with a contact-charging means for charging the photosensitive member.

Abstract: A magnetic developer for developing an electrostatic latent image, including hydrophobic silica fine powder and an insulating magnetic toner comprising at least a binder resin and a magnetic material comprising spherical magnetic particles; wherein 0.16 to 1.6 wt. parts of the hydrophobic silica fine powder is mixed with 100 wt. parts of the insulating magnetic toner; the developer contains 17-60% by number of magnetic toner particles having a particles size of 5 microns of smaller, 5-50% by number of magnetic toner particles having a particle size of 6.35-10.08 microns, and 2.0% by volume or less of magnetic toner particles having a particle size of 12.7 microns or larger.

Abstract: The present invention provide a toner for developing an electrostatic image. The toner comprises a binder resin and a coloring agent. The binder resin comprises a styrene type binder resin. The amount of an aldehyde contained in the binder resin is not more than 0.005% by weight based on the weight of the toner. The binder resin is produced by a process comprising the steps of preparing a monomer composition comprising a polymerizable monomer containing at least not less than 50% by weight of a styrene monomer, and a polymerization initiator, and subjecting said monomer composition to suspension polymerization in an aqueous medium having dissolved oxygen in an amount of not more than 2.5 mg/lit to form a styrene polymer or copolymer containing an aldehyde monomer in an amount of not more than 0.01% by weight.

Abstract: A dry developer for developing electrostatic images comprises a) toner particles comprising 100 parts by weight of a binder resin and 1-20 parts by weight of polyalkylene having a ratio of weight average molecular weight to number average molecular weight of 2.0-10.0 and Z average molecular weight determined by gel permeation chromatography of 10,000-200,000, and containing 5-60% by weight of a component soluble in n-hexane at boiling point, kinetic friction coefficient of the toner particles being 0.20-0.50, and b) non-magnetic inorganic fine powders having BET specific surface area according to a nitrogen adsorbing method of 0.5-500 m.sup.2 /g.An image forming method comprises using the dry developer to develop electrostatic latent images on a photosensitive member having a surface hardness of 8 g or more, transferring the developed images to a receiving member, and removing the toner particles remaining on the photosensitive member by a cleaning means accompanying abrasion.

Abstract: A triboelectrically chargeable composition for use in development of electrostatic latent images. The composition comprises a positively chargeable compound and a base material carrying the positively chargeable compound. The positively chargeable compound has an oxidation potential of 750 mV or below, a whiteness W of 0.5 or above and an average particle size of 5.0 microns or smaller. The composition is embodied typically as a positively chargeable toner and also as a charge-imparting material for charging a toner. The positively chargeable toner is especially adapted for development of digital latent images, e.g., as produced by laser beam scanning.

Abstract: A dispersion stabilizer having a nitrogen-containing organic group and a water-soluble acidic substance are added to an aqueous medium. Into the aqueous medium, a monomer composition comprising at least a polymerizable monomer, an anionic polymer, a polymerization initiator and a colorant is added and dispersed therein into a prescribed particle size. The particles of the monomer composition are subjected to suspension polymerization. The resultant toner is caused to have a sharp particle size distribution and an improved anti-blocking property because of the combined effects of the dispersion stabilizer and the acidic substance contained in the aqueous medium and the anionic polymer contained in the monomer composition.

Abstract: A process for preparing a toner obtained by a suspension polymerization method comprises stirring a mixture containing at least a polymerizable monomer containing 5 to 500 ppm of a polymerization inhibitor dissolved in the polymerizable monomer and a colorant; preparing a polymerizable monomer composition by adding a polymerization initiator to said mixture; stirring the prepared polymerizable monomer composition; and carrying out suspension polymerization of the polymerizable monomer composition dispersed in an aqueous medium.

Abstract: A positively chargeable developer, comprising: positively chargeable toner particles, positively chargeable silicate fine powder having a positive triboelectric chargeability higher than that of the toner and a mean particle size of 3 microns or smaller, and a microdisperser having a triboelectric chargeability lower than that of the toner and a mean particle size which is larger than that of the silicate powder and smaller than that of the toner particles. The microdisperser has a function of disintegrating particularly the positively chargeable silicate fine powder and enhances the attachment thereof to the toner particles, whereby the developing characteristics including the triboelectric chargeability are stabilized from the initial stage of electrophotographic copying operation, and the storage stability is also improved.

Abstract: A dry developer for developing electrostatic images comprises (a) toner particles comprising 100 parts by weight of a binder resin and 1-20 parts by weight of polyalkylene having a ratio of weight average molecular weight to number average molecular weight of 2.0-10.0 and Z average molecular weight determined by gel permeation chromatography of 10,000-200,000, and containing 5-60% by weight of a component soluble in n-hexane at boiling point, kinetic friction coefficient of the toner particles being 0.20-0.50, and (b) non-magnetic inorganic fine powders having BET specific surface area according to a nitrogen adsorbing method of 0.5-500 m.sup.2 /g.An image forming method comprises using the dry developer to develop electrostatic latent images on a photosensitive member having a surface hardness of 8 g or more, transferring the developed images to a receiving member, and removing the toner particles remaining on the photosensitive member by a cleaning means accompanying abrasion.

Abstract: An electrostatic image is developed by disposing an electrostatic image bearing member which holds an electrostatic image on its surface and a developer carrying member which carries an insulating developer on its surface with a certain gap provided therebetween, at a developing section bringing an insulating developer containing a nitrogen-containing compound to a thickness thinner than the gap on the developer carrying member and transferring said developer onto the above electrostatic image bearing member at the developing section. The nitrogen-containing compound has nitrogen in the form of a heterocyclic ring and imparts stable positive chargeability to the developer.