Abstract: The invention relates to a developer for developing electrostatic images. The developer includes magnetic carrier particles at a loading of from 60 to 99 weight percent of the developer. Toner particles are at a loading of 1 to 40 weight percent of the developer. The toner particles include a resin core particle having an outer surface and 0.05 to 5 weight percent a first metal oxide powder is substantially fixed to the outer surface. The toner particles further include 0.05 to 2 weight percent of a second metal oxide powder that is substantially free to transfer between outer surface of the toner particles and an outer surface of the magnetic carrier surface.

Abstract: It is contemplated to provide irregular shaped ferrite carrier which has a lower resistance, a high specific surface area, a low specific gravity and a longer operational life, and an electrophotographic developer comprising the ferrite carrier which prevents the toner scattering, has a high image density, and is responsive to high-speed and color imaging. The irregular shaped ferrite carrier is characterized in that the carrier particles are irregular shaped, and 40 percent by number or more of the particles have a rock candy sugar shape and/or an oyster shell shape, and that the shape factor (SF-1=R2/S×?/4×100, wherein R is a maximum length and S is a projected area.) is 140 to 250, and the distribution width (?) is 60 or less.

Abstract: Carrier particles for forming a wiring circuit pattern by an electrophotographic developing method which are used for directly forming a circuit shape on an insulating layer, with any of a metal powder, an inorganic compound powder, or a mixed raw material powder thereof used as a toner powder for forming a circuit, the toner powder for forming a circuit being adhered to a surface of the carrier particles by electrostatic force and then transported to a surface of the insulating layer, wherein the carrier particles include a resin coated layer of an acrylic resin composition containing an amino-group-containing polymer on the surface of the carrier core material particles, the coating amount of the acrylic resin composition is 0.3 to 3.0% by weight based on a carrier core material weight of 100% by weight, and a shape factor SF-1 of the carrier core material particles is 100 to 110.

Abstract: Provided is a two-component developer with which degradation of development is inhibited even in the case of prolonged use, and thereby a high quality image exhibiting high resolution and sufficient image density can be formed for a long duration. Also disclosed is a two-component developer possessing a carrier and a toner, wherein the carrier in which magnetic material powder is dispersed in a binder resin containing a phenol formaldehyde resin has a shape coefficient SF-1 of 1.0-1.2, a shape coefficient SF-2 of 1.1-2.5 and a volume-based median particle diameter of 10-100 ?m, and the toner possesses a colored particle and an external additive particle, wherein the external additive particle comprises a titanic acid compound and iron, and the iron content is 100-1,000 ppm, based on the titanic acid compound.

Abstract: There is provided a toner having narrow charge distribution, high chargeability and low image contamination, as well as excellent physical properties such as long-term stability, transfer property and image uniformity, by improving shapes of toner core particles and adding a suitable external additive to surfaces of the toner core particles. The toner includes spheroidized toner core particles; and an external additive coated onto surfaces of the toner core particles, wherein the external additive comprises organic powder, silica and spherical titanium dioxide powder. The toner may be useful to obtain a highly uniform and high-quality image even when the toner of the present invention is used for an extended time since the toner has high chargeability, excellent image uniformity in which charge uniformity and narrow charge distribution are maintained for a long time, low image contamination, as well as excellent physical properties such as transfer property and long-term stability.

Abstract: A toner patch including a toner having a given excitation wavelength and a given emission wavelength may be deposited onto a control surface. Light may be provided onto the toner patch and at least a portion of emitted light may be detected from the toner patch at the given emission wavelength by a detector. Furthermore, an operating parameter may be adjusted based on the detected emitted light.

Abstract: Pigment particles with at least one metal oxide surface additive, wherein the at least one metal oxide surface additive is a metal oxide particle covalently bonded with at least one polycondensation polymer, wherein the pigment particle is a pearlescent or metallic pigment.

Abstract: Single component toners having a core with a first latex having a specific glass transition temperature and molecular weight, further having a shell surrounding the core with a second latex having a specific glass transition temperature and molecular weight, and additives added thereto, and processes for producing the same. In embodiments, the toner is a non-magnetic single component toner produced by emulsion aggregation methods.

Abstract: It is an object of the present invention to provide a toner containing toner particles and inorganic fine particles wherein the inorganic fine particles are externally added to the toner particles which contain a binder resin and a colorant and at least one type of the inorganic fine particles is a compound oxide having a relative permittivity measured at 1 MHz of 2 to 10 and a volume resistivity of 1011?·cm or more and an image forming method using the toner.

Abstract: The present invention relates to a magnetic mono-component toner composition with positive charge comprising i) a magnetic toner particle containing a charge control agent with positive charge; ii) a hydrophobic silica with negative charge; iii) a fluorinated organic fine powder; and iv) a metal oxide fine powder containing 20 to 80 wt % of tin oxide. The toner has an advantageous in the extended life of the drum, reduction of the background contamination, and improvement of long-term reliability, and thus can be used effectively for image forming apparatus.

Abstract: A toner for developing electrostatic images which contains an external additive A containing an irregular-shaped metal oxide and having an average value of the feret's horizontal diameter of from 20 nm to 1370 nm, and an external additive B containing a hydrophobic particle having an average value of the feret's horizontal diameter of from 10 nm to 45 nm.

Abstract: Disclosed is a toner which can be charged at a designated level even when a lot of print is carried out with severity of charging by stirring and when the printing is carried out under the low temperature-low humidity or the high temperature-high humidity condition. A toner comprising (a) a particle comprising a resin and a colorant; and (b) a titanate compound on the surface of the particle, in which the titanate compound contains iron in an amount of from 100 ppm to 1,000 ppm.

Abstract: An image forming method including charging an image bearing member by applying combination of DC voltage and AC voltage with frequency of 6.5 to 8.5 cycle/mm; irradiating the image bearing member with light to form an electrostatic image; developing the electrostatic image with a developer including toner to form a toner image; transferring the toner image onto a receiving material; fixing the toner image; cleaning the image bearing member with a blade; then applying a lubricant to the image bearing member; and then spreading the lubricant with a spreading member countering the image bearing member. The toner includes toner particles granulated in an aqueous medium; and at least three kinds of external additives including a first particulate hydrophobic silica, a particulate hydrophobic titanium oxide and a second particulate hydrophobic silica respectively having BET specific surface areas of 20 to 40 m2/g, 40 to 80 m2/g, and 130 to 300 m2/g.

Abstract: Disclosed is an electrostatic charge image developing toner containing external additives possessing at least amorphous silica and a crystallized metal oxide selected from titanium oxide, aluminum oxide, zirconium oxide, or calcium oxide, wherein the amorphous silica is placed as a nucleus, and the crystallized metal oxide is present on the silica surface.

Abstract: A toner is provided which can stably provide a favorable density stability, line reproducibility and dot reproducibility even in high-speed copying machines, printers and the like which form high resolution latent images over a long period regardless of environmental conditions, and can provide the image quality adaptable to embedded pattern printing, QR code printing and the like. The present invention is characterized in that the toner which includes toner particles including at least a binder resin and a colorant, and a fine silica powder, has a volume median diameter (D50) of not less than 0.70 ?m and not more than 3.00 ?m, and a total pore volume of not more than 0.200 cm3/g, measured in the range of the pore diameter from not less than 1.7 nm and not more than 300.0 nm.

Abstract: A developing agent includes a carrier; a toner in which an inorganic oxide external additive has a coverage of from 60 to 120% relative to a core toner; and a charging auxiliary particle having charge properties of a positive electrode and having a volume average particle size of from 5 to 15 ?m in an addition amount of from 0.5 to 6% by weight relative to the developing agent.

Abstract: A toner manufacturing method is provided including emulsion-polymerizing monomers including an aromatic vinyl monomer, to prepare a particulate resin dispersion; mixing the particulate resin dispersion and a colorant dispersion including a black metallic material, to prepare an aggregation dispersion including aggregated resin particles including the colorant therein; heating the aggregation dispersion to a temperature of not less than a glass transition temperature of the particulate resin to unite each of the aggregated particles to prepare a toner dispersion; and washing the toner dispersion to obtain the toner; a toner manufactured by the above method, and a developer using the toner.

Abstract: The present invention provides a toner for electrostatic latent image development and a method of magnetic monocomponent development using the toner which can prevent the toner adhesion to a photoconductor for a long time period and can obtain an image having high quality by maintaining functions of the toner for a long time period or by favorably adjusting the conveying property of the toner on a developing sleeve. In a toner for electrostatic latent image development which contains toner particles and inorganic particles and a method of development using the toner, the toner particles exhibit a shape factor SF-1 which satisfies the relationship 115?SF-1?150 and a shape factor SF-2 which satisfies the relationship 115?SF-2?145 and, at the same time, a quantity of inorganic particles which are in a floating state is set to a value which falls within a range from 10 weight % to 25 weight % with respect to the total quantity of the inorganic particles.

Abstract: An electrostatic charge image developer includes a toner containing an external additive and a carrier comprising a resin-coated layer formed on a surface of a core material. The average shape factor SF1 of the toner is from 125 to 135, the number of particles having shape factor SF1 of less than 125 is from 5% to 30% by number with respect to the total number of toner particles, the number of particles having shape factor SF1 of greater than 135 is from 5% to 30% by number with respect to the total number of toner particles, the scratch line width in a scratch strength test of the resin used in the resin-coated layer is from 80 ?m to 200 ?m, and the scratch depth is from 60 ?m to 150 ?m.

Abstract: Toner particles, including at least one binder, at least one colorant, and at least one metal surface additive, wherein the at least one metal oxide surface additive is a metal oxide particle covalently bonded with at least one polycondensation polymer.

Abstract: An emissive toner composition for producing an emissive image component of an image indicia on a substrate. The emissive toner composition includes a photoluminescent agent, a charge control agent, and one or more additives, each selected and present in an amount such that when the toner composition is printed to produce an image component on a substrate, the toner composition has stable spectral characteristics. In one embodiment, the emission spectra of the image component printed on the substrate, for irradiation with an excitation energy includes only dominant emission peaks corresponding to one or more emission peaks of the photoluminescent agent. In another embodiment, the image component has a photoluminescent toner stability factor of about greater than or equal to 25.

Abstract: Disclosed is an electrostatic charge image developing toner containing external additives comprising at least amorphous silica and a crystallized metal oxide selected from titanium oxide, aluminum oxide, zirconium oxide, or calcium oxide, wherein the amorphous silica is present on the crystallized metal.

Abstract: An image forming method, includes: forming a latent electrostatic image on a latent electrostatic image carrier; developing the latent electrostatic image with a toner to thereby form a visible image; transferring the visible image to a recording medium; and fixing the image transferred to the recording medium. The latent electrostatic image carrier includes: a support, a photoconductive layer on the support, and a surface protective layer on the support. The surface protective layer includes a reactant made by cross-linking the following: an electric charge transporting material which comprises a reactive functional group, a cross-linking resin, and a fluorine surfactant. The toner comprises an inorganic fine particle which defines an effective inorganic fine particle amount in a range of 0.8% by mass to 3.

Abstract: In a black toner having at least a binder resin and an iron-titanium composite oxide as a colorant; the iron-titanium composite oxide is contained in a specific amount; the black toner has a specific weight average particle diameter and a specific saturation magnetization; the black toner has, in X-ray diffraction thereof, a maximum peak at 2?=from 32.5 to 33.1 degrees, having a half width of 0.25 degree or less. The black toner has, in a proportion of less than 30% by number, an iron-titanium composite oxide having, in a sectional photograph of the toner, a maximum frequency of linearity within the range where the linearity is smaller than 2.4 and having a linearity of 3.0 or more, in regard to the number frequency distribution of the linearity of the iron-titanium composite oxide.

Abstract: An electrophotographic toner is provided including parent toner particles having a small average particle diameter and external additives applied to the surface of the parent toner particles. The external additives include: a large particulate silica; a small particulate silica; a conductive titanium oxide; strontium titanate; and an aluminum oxide. High-quality and high-speed imaging can be performed using the toner since the amount of toner charge can be stably maintained for both initial and long-term use.

Abstract: An electrophotographic toner for visualizing an electrostatic latent image formed by an electrophotographic process, an electrostatic printing process, an electrostatic recording process, etc., which is produced in consideration of the environment and safety. The electrophotographic toner includes a fixing resin and a colorant. The electrophotographic toner is a black toner using a titanium compound containing no carbon black as the colorant. The electrophotographic toner may be an electrophotographic two-component black toner using magnetic iron oxide containing no carbon black as the colorant.

Abstract: Disclosed is a magnetic one-component toner for development of an electrostatic latent image used in a magnetic one-component jumping development system in which a photoconductor is an a-Si photoconductor having a thickness of 30 ?m or less and Rz of a developer carrier is from 2.0 to 6.0 ?m. A cleaning means for removing the toner from the surface of the photoconductor is a cleaning blade. Titanium oxide, as an external additive, is added to the toner. The titanium oxide has a liberation rate within a range from 10 to 22% and contains a low resistance titanium oxide having a volume resistivity within a range from 100 to 107?·cm and a high resistance titanium oxide having a volume resistivity within a range from 108 to 1013?·cm, a mass ratio of the low resistance titanium oxide to the high resistance titanium oxide within a range from 1.3:1 to 4:1.

Abstract: The toner includes emulsion aggregation toner particles of a binder including a non-crosslinked styrene acrylate polymer, at least one colorant, at least one wax, and aluminized silica, wherein an amount of aluminum metal in the toner particles is from about 50 ppm to about 600 ppm. Such toner is able to provide a high level of gloss while maintaining a low minimum fixing temperature. The aluminized silica acts as a coagulant during the emulsion aggregation formation process of the toner.

Abstract: It is an object of the present invention to provide a toner that can sustain favorable transferability and cleaning ability for prolonged periods; prevent photoconductor filming; exhibit no variation in image nonuniformity or external additive immersion induced by developer agitation at the time of use; excels in stability with flowability and charge stability over prolonged periods. Therefore, provided is the toner of which the quantity of aggregate of residual external additives found on the sieve of 635-mesh and 452 cm2 of mesh area, after 0.2 g of the toner on the sieve is blasted with air at a blow pressure of 0.2 MPa from 160 mm above the sieve while being air-suctioned at a suction force of 5 mmHg, and then air-suctioned at a suction force of 20 mmHg, is 4,500 or less and 5 or more.

Abstract: An image forming apparatus and process cartridge which uses a two-component developer comprising a toner and a carrier. By using toner and carrier having a small-particle size, deterioration of the toner fluidity over time can be avoided, and further by maintaining stable toner charge even in a low-humidity environment, stable high-quality image formation can be achieved. The occurrence of adherence of carrier to the solid portions of the toner image is reduced in addition to the occurrence of adherence of carrier to the edge portions, and image abnormalities, toner scattering and the like are prevented.

Abstract: A toner is disclosed, for developing electrostatic images by means of image forming apparatuses, that comprises toner particles, and an external additive, wherein the toner particles comprise a binder resin and a colorant, the external additive is introduced onto the surface of the toner particles, the external additive liberates from the surface of the toner particles in a rate of 7% to 50% under the condition that the toner is dispersed within a surfactant-containing electrolyte at 20 W output power and 20 kHz frequency for one minute by means of an ultrasonic homogenizer.

Abstract: The present invention is to provide a nonmagnetic one-component toner containing a colorant, and a binder resin, wherein metal oxide fine particles are fixed on a toner surface with an adhesion strength of 95% to 99%, the toner has a direct current resistance of 1E7 ?·cm to 1E9 ?·cm, and an electrostatic capacity of 1.0E-12F to 1.5E-11F.

Abstract: An objective is to provide an electrostatic latent image developing toner exhibiting ultra-low temperature fixability together with high resolution, excellent fluidity and anti-blocking property, and excellent aging stability in a toner vessel, in which the toner is supplied into an image forming apparatus. Also disclosed is an electrostatic latent image developing toner stored in a vessel possessing an ejecting outlet, capable of fitting into an image forming apparatus, wherein the vessel has a cross-sectional area of the outlet of 0.07-2.00 cm2; the toner possesses a resin, a colorant and an external additive; the toner has a Tg of 16-44° C.; an X-ray intensity ratio of Ti/Si via fluorescent X-ray analysis of toner, is 1.0-2.5; and toner particles, and having a ratio of 2nd short axis to 1st short axis being 1.1-1.6 have an amount of 5-50% in terms of the number of particles.

Abstract: A magnetic black toner for electrophotography comprising a binding resin, a magnetic substance, and a pigment, wherein the pigment is at least one of phthalocyanine pigment and Mn containing hematite, and the content ratio of the magnetic substance and the pigment in the toner satisfy the following formulae: 10?A?30, 0.1?B?3, 5?C?40, wherein A denotes the content ratio (mass %) of the magnetic substance in the toner, B denotes the content ratio (mass %) of the phthalocyanine pigment in the toner, and C denotes the content ratio (mass %) of the Mn containing hematite in the toner.

Abstract: Provided is an electrophotographic developing agent including: toner particles including a binder resin, a colorant, and a charge control agent; and an external additive added to the surface of the toner particles, wherein the external additive includes at least one inorganic particulate component and at least two types of strontium titanate particulate component having different mean primary particle diameters. Typically, the inorganic particulate component is not strontium titanate. Also, an electrophotographic image forming apparatus using the electrophotographic developing agent is provided. The strontium titanate particulate component having different mean primary particle diameters are used as an external additive to maintain uniform charging characteristics and to prevent fog in a non-image area, thereby obtaining good image quality.

Abstract: In order to solve the foregoing inconveniences, specified addition amounts of a low-resistance external additive and a high-resistance external additive are used in this invention. Furthermore, the toner having been subjected to external addition is subjected to cyclone classification to separate the external additives by force, thereby producing a toner in the same state as in the toner to which a mechanical stress has been applied within the developing unit. When a value of resistance of the toner after externally adding the external additives and a value of resistance of the toner after cyclone classification and a relationship between the both are specified as described later, so far as they fall within the specified ranges, it is possible to provide a developing agent which is free from deterioration of the image quality and is less in toner scattering even by an environmental change or after long-term use.

Abstract: There is provided a toner which contains at least a binder resin, and filler including a layered inorganic compound, wherein the layered inorganic compound is cleaved to form particles in the toner, and the particles have a breadth of 0.5 nm to 4 nm, and a length of 10 nm to 90 nm.

Abstract: A toner, including a parent particulate material including a colorant and a binder resin, and an external additive including particles having an average primary particle diameter from 80 to less than 150 nm in an amount of from 0.03 to 2% by number, particles having an average primary particle diameter from 5 nm to less than 15 nm in an amount of from 50 to 95% by number, and particles having an average primary particle diameter from 15 to less than 40 nm in an amount of from 5 to 40% by number, and the particles having an average primary particle diameter from 80 to less than 150 nm include particles having an average primary particle diameter not less than 200 nm in an amount of from 10 to 30% by number, and have a weight reduction rate not greater than 3.00% when heated from 30 to 250° C.

Abstract: The present invention provides a toner for electrostatic latent image development and a method of magnetic monocomponent development using the toner which can prevent the toner adhesion to a photoconductor for a long time period and can obtain an image having high quality by maintaining functions of the toner for a long time period or by favorably adjusting the conveying property of the toner on a developing sleeve. In a toner for electrostatic latent image development which contains toner particles and inorganic particles and a method of development using the toner, the toner particles exhibit a shape factor SF-1 which satisfies the relationship 115?SF-1?150 and a shape factor SF-2 which satisfies the relationship 115?SF-2?145 and, at the same time, a quantity of inorganic particles which are in a floating state is set to a value which falls within a range from 10 weight % to 25 weight % with respect to the total quantity of the inorganic particles.

Abstract: An external additives for electrophtographic toner comprising finely divided oxide particulate including a silicon compound and a compound for doping said oxide particulate, wherein particle diameter of the primary particle of said finely divided oxide particulate is in the range of 30 nm to 150 nm, and the primary particle of said finely divided oxide particles is substantially spherical shape having the roundness in the range of 0.95 to 0.996, is provided. And this external additives is capable of evading from the embedding of external additives into toner even if after the toner is held in the storage under the condition of high temperature and high humidity, thereby the additives is capable of showing sufficient functions as fluidizing agent and charge supplement agent, and is capable of inhibiting an abnormal charge elevation even after being stored under the low temperature and low humidity.

Abstract: The present invention relates to oxidation-stable iron oxide pigments which have a coating of at least one organic substance, to their preparation and to their use.

Abstract: A toner for developing electrostatic images in a single component development (SCD) system free of carrier and including emulsion aggregation toner particles of a styrene acrylate polymer binder, at least one release agent and at least one colorant, wherein the toner particles have a volume average particle size of from about 5 ?m to about 10 ?m, an average circularity of about 0.95 to about 0.99, a volume and number geometric standard deviation (GSDv and n) of from about 1.10 to about 1.30, and an onset glass transition temperature of from about 45° C. to about 65° C., is ideally suited for forming an image using a single component image forming device.

Abstract: A toner comprising a compound represented by the following formula: R1O(R2O)nH where R1 is an aliphatic hydrocarbon group having 10 to 22 carbon atoms or a distyrene-substituted phenyl group; R2 is an alkylene group having 2 to 6 carbon atoms; and n is an integer of 1 to 15.

Abstract: Toner including toner particles having a calcium-containing material at least in a surface portion of the toner particle, wherein the toner particles contain calcium in an amount of from 20 ppm to about 300 ppm of calcium by dry weight of the toner. Developer including a carrier and a toner, wherein the toner includes toner particles having a calcium-containing material at least in a surface portion of the toner particles. In an emulsion aggregation process for making toner particles, the toner particles are treated with calcium. The addition of calcium to the toner particles improves toner performance by lowering cohesion and charging, thereby generating an image of high gloss.

Abstract: The present invention provides a toner improved in dispersibility of a colorant in the toner particles and excellent in the color reproducibility including color mixability and transparency. The toner is also excellent in the stability in long-term of the chargeability and capable of forming images maintaining high image quality. The present invention provides a toner for forming a full-color image which includes at least toner particles containing a binder resin, a colorant and a wax, and inorganic fine particles, wherein the binder resin comprises a resin having polyester units which is synthesized by use of an aromatic carboxylic acid titanium compound as a catalyst, and the inorganic fine particles comprise fine titanium oxide particles.

Abstract: A carrier and a two-component developer are provided. A coating resin layer for coating a core material contains fine particles of titanium oxide which comprise an anatase-type crystal and a rutile-type crystal, and a carrier coating amount of the coating resin layer falls in a range of from 5% by weight to 20% by weight. In addition, a content rate of the rutile-type crystal falls in a range of from 5% to 20% on the basis of the total amount of crystal, and the weight of the fine particles of titanium oxide falls in a range of from 5% by weight to 50% by weight relative to the weight of the core material. Further, the primary particle size of the fine particles of titanium oxide falls in a range of from 40 nm to 80 nm.

Abstract: A toner composition for an electrophotography image forming apparatus includes toner particles and external additives. The toner particles include a colorant, a charge control agent and a release agent with binder resins. The external additives include a first silica having an opposite polarity to the toner particles, a second silica having the same polarity as the toner particles, a sodium titanate having the same polarity as the toner particles, and an aluminum oxide having the same polarity as the toner particles.

Abstract: The present invention provides An image forming apparatus having: a negatively chargeable spherical toner; an latent image carrier; a charging member for charging a surface of the latent image carrier uniformly without contacting the latent image carrier; an electrostatic latent image forming member for forming an electrostatic latent image on the surface of the latent image carrier; a developing member for developing the electrostatic latent image, without contacting the latent image carrier, by using the negatively chargeable spherical toner so as to form a toner image on the latent image carrier; and an intermediate transfer medium to which the toner image is transferred, wherein the negatively chargeable spherical toner haves: a toner mother particle having a binder resin and a colorant; and a hydrophobic alumina particle as an external additive, wherein the hydrophobic alumina particle has a work function (?A1) larger than a work function (?TM) of a surface of the intermediate transfer medium.

Abstract: The present invention provides a negatively chargeable spherical toner having: a toner mother particle having a binder resin and a colorant, which has: a number average particle size of from 4.5 to 9 ?m; a particle size distribution that has an integrated value of particle sizes of 3 ?m or less of 1% or less; and an average sphericity of from 0.95 to 0.99; and an alumina fine particle externally added to the toner mother particle, which has a number average particle size of from 0.1 to 1.0 ?m, wherein a work function (?t) of the toner mother particle is larger than a work function (?A) of the alumina fine particle by at least 0.4 eV.

Abstract: An object of the present invention is to provide a toner for development of an electrostatic latent image, which has excellent developability and which is used in an electrophotographic image forming apparatus. One aspect of the present invention pertains to a toner for development of an electrostatic latent image, comprising cylindrical toner particles and titanium oxide particles added externally to the cylindrical toner particles, wherein the titanium oxide particles have an average primary particle size within a range from 10 to 100 nm, and the titanium oxide particles have a specific volume resistivity value within a specific range. Such a toner for development of an electrostatic latent image suppresses an image deletion phenomenon and is excellent in charge characteristics, and also exerts an extremely excellent effect on long-term printing durability.