Abstract: An electrophotographic toner constituting a dual component is composed of toner base particles and fine inorganic particles having a volume mean diameter of 250 to 600 nm with a specific surface area of 0.25 to 0.5 m2/g for serving as an abrasive, and is characterized in that 1.5 to 2 parts by weight of the abrasive is externally added to 100 parts by weight of the toner base particles and made to be deposited over the toner base particle surface. Also, the above electrophotographic toner is used for an electrophotographic apparatus which includes a photoreceptor cleaning device located above the level that passes through the center of the photoreceptor drum.

Abstract: A toner, wherein at least a part of inorganic fine particles is fixed on the surface of core particles made of a binder resin containing a colorant, by applying heat in a hot air flow, is designed so as to satisfy the following expression: 2.0×[6/(&rgr;D)]≧S≧1.1×[6/(&rgr;D)]  (1) where S: toner BET specific surface area, &rgr;: toner specific gravity, and D: toner volume average particle size. Thus, it becomes possible to manufacture a toner that is superior in various properties in a stable manner.

Abstract: A particle surface improving method for forming a film of a surface improving agent that improves the property of a particle surface by exposing particles to a supersaturation atmosphere of the surface improving agent to let the surface improving agent condense on the particle surface. This method can improve the particle surface by a simpler manipulation in a shorter time without charging the particles.

Abstract: A method of manufacturing electrophotographic toner according to the present invention includes the step of mixing at least toner particles and an additive for a predetermined mixing time to produce the toner, with the predetermined mixing time being set within a range from a first mixing time, at which chargeability of the toner (which changes according to the duration of mixing of the toner particles and the additive) shows a singular point, through a second mixing time, at which preservation of the toner (which also changes according to the duration of mixing) shows a singular point. By this method, a mixing time which maximizes the effects of the additive can be easily set. Accordingly, using a method simpler than conventional methods, a toner can be obtained which has good characteristics with regard to both chargeability and preservation.

Abstract: A binder resin as the main component of the toner has a low molecular weight polypropylene as a separating agent, encapsulated therein. Using this binder a toner with the wax having a diameter of 0.3 .mu.m or less dispersed therein is produced. The wax is included 0.5 part to 5 parts by weight for 100 parts by weight of the binder resin. This limitation of the toner prevents the setoff phenomenon during the fixing process and at the same time prevents the filming phenomenon over the photoreceptor and achieves an improved fixing performance.

Abstract: In toner 1 containing a binder resin 2, wax particles 3 and a coloring agent, the wax particles 3 are designed so that the ratio of major axis/minor axis is set in the range of 1.4 to 4.0 and so that the major axis L is not more than 6.0 .mu.m. Moreover, the melt index of the binder resin ranges from 5.0 to 11.0, and the dielectric loss tangent (tan .delta.) is not more than 5.0. This arrangement prevents the wax particles 3 inside the toner 1 or at the toner 1 surface layer from exposing to or sticking out of the toner 1 surface, thereby making it possible to provide a superior offset-reducing property during the fixing process and electrophotographing toner that can reduce wax contamination on the surface of the toner-bearing body.

Abstract: A process for preparing a toner includes forming a melt-kneaded mixture by mixing a raw material mixture containing a quaternary ammonium salt compound at a temperature ranging from (M-7).degree. C. to (M+7).degree. C., where M is a melting point of the quaternary ammonium salt compound, with a kneading device having a discharge port whose temperature is set lower than a temperature at which a melt viscosity of the melt-kneaded mixture at the discharge port is not higher than 10,000 Pa.a, removing the melt-kneaded mixture from the kneading device, rolling out the melt-kneaded mixture to a thickness ranging from 1.2 mm to 3.0 mm, and cooling down the melt-kneaded mixture. With the use of the toner produced by this process, the amount of charge during copying is retained in an appropriate range irrespectively of the working atmosphere and conditions of use, thereby maintaining a good image density.

Abstract: An electrophotographic toner is made up of toner particles composed of irregularly-shaped core particles made chiefly of binder resin, and surface-modifying fine particles which are first dispersed over and attached to the surface of the core particles, and then affixed or formed into a film thereon. The BET specific surface area, based on N.sub.2 adsorption, of the toner particles is less than 0.64 times the BET specific surface area of the core particles and surface-modifying fine particles combined together. Further, this value is 1.07 times the BET specific surface area of hypothetical toner particles which are perfect spheres. Consequently, the toner is not prone to problems such as filming, toner scattering, and fogging which are caused by peeling, separation, etc. of the surface-modifying fine particles, nor to poor cleaning due to spherical toner particles.

Abstract: The present invention provides electrophotographic printing-use toner capable of producing a quality image, without depending on excessive addition of a fluidizing agent, even after maintained at high temperature which causes toner to aggregate. The electrophotographic printing-use toner constituting two-component developer with magnetic powder carrier, made of a toner mother particle including binding agent synthetic resin and a coloring agent, whose surface is added with a fluidizing agent is manufactured so that a ratio of .DELTA.Q.sub.h /.DELTA.Q.sub.s is not less than 0.37, more preferably not less than 0.45, where .DELTA.Q.sub.s is a charging rate of the toner mother particle, at a start of mixing with respect to the magnetic powder carrier, maintained at normal temperature, and .DELTA.Q.sub.h is a charging rate of the toner mother particle, at the start of mixing, maintained under a condition of temperature and time which causes the electrophotographic printing-use toner to aggregate.

Abstract: The extra-fine toner arising in the toner producing process, is returned to the mixing step where it is mixed again with the binder resin and the coloring agent, and the compound is sent out to the kneading step. In this procedure, the particle size of the binder resin is set in accordance with the particle size and blending amount of the extra-fine toner, the kind of the binder resin, etc. By using the binder resin having the thus determined particle size, the amount of the binder to be fed into the mixer or the amount of the compound ejected from the mixer are maintained uniform. Further, when the extra-fine toner is mixed with the starting materials, the blending ratio of the extra-fine toner to the starting material is set between 5 wt. % and 10 wt. %, and the blending ratios of the charge control agent and the coloring agent are set equal to those of the normal process where no recycled toner is added.

Abstract: A toner producing system which can efficiently produce toner having a sharp particle size distribution by suppressing the occurrence of microscopic powders and improve energy efficiency in pulverization. The system is furnished with a second pulverizing apparatus having a second colliding plate inclined at an angle in a range between 45.degree. and 90.degree. inclusive with respect to a direction in which a raw material subject to pulverization is introduced into a second pulverizing chamber through a second nozzle, and a third pulverizing apparatus having a third colliding plate with a conical member being placed thereon, so that the raw material introduced into a third pulverizing chamber through a third nozzle collides with an inner surface thereof following the collision with the third colliding plate.

Abstract: The electrostatic charge image-developing toner contains a colorant, a binder resin, and polyethylene having a melt viscosity of 22000 to 26800 mPa.multidot.s at 140.degree. C. This electrostatic charge image-developing toner prevents an offset phenomenon on the surface of a fixing roller, and does not adhere to and fuse on a photoreceptor drum to cause no stripy and dotwise stain on a reproduced image, that is, preventing a so-called filming phenomenon. The toner also prevents an offset phenomenon on the photoreceptor drum.