# US 7,608,377 B2 · Image forming method and image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,377 B2 - Document ID: US7608377B2 - Status: Granted - Kind: B2 - Application number: 11/519,057 - Filed: 2006-09-12 - Published: 2007-03-15 - Granted: 2009-10-27 - Earliest claimed: 2005-09-13 - Assignees: Ricoh Company, Ltd. - Inventors: Shinya Nakayama; Hisashi Nakajima; Hideki Sugiura; Fumihiro Sasaki; Akihiro Kotsugai; Satoshi Mochizuki - Web page: https://patentgrep.com/patent/US7608377B2 ## CPC - G03G 15/2007: {using radiant heat, e.g. infrared lamps, microwave heaters} - G03G 9/0827: {characterised by their shape, e.g. degree of sphericity} - G03G 9/09708: {Inorganic compounds} - G03G 9/09716: {treated with organic compounds} - G03G 9/09725: {Silicon-oxides; Silicates} - G03G 15/20: for fixing, e.g. by using heat - G03G 15/2064: {combined with pressure} - G03G 2215/0602: Developer - G03G 2215/2016: Heating belt - G03G 2215/2032: the belt further entrained around additional rotating belt support members - G03G 2215/2035: the fixing nip having a stationary belt support member opposing a pressure member - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract To provide an image forming method including forming a latent electrostatic image on a latent electrostatic image bearing member, developing the latent electrostatic image using a toner to form a visible image, transferring the visible image to a recording medium, and fixing a transfer image transferred on the recording medium, wherein the toner includes a toner base particle containing at least a binder resin, a colorant and an inorganic fine particle, and a charge control agent; and wherein the condition Xsurf>Xtotal is satisfied (where Xsurf is an average proportion of the inorganic fine particles in a near-surface region of the toner base particle, Xtotal is an average proportion of inorganic fine particles in the whole toner base particle. ## Claims ### Claim 1 An image forming method comprising: forming a latent electrostatic image on a latent electrostatic image bearing member; developing the latent electrostatic image using a toner to form a visible image; transferring the visible image to a recording medium; and fixing a transfer image transferred on the recording medium, wherein the toner comprises a toner base particle containing at least a binder resin, a colorant and inorganic fine particles, and a charge control agent, and wherein the condition Xsurf>Xtotal is satisfied (where Xsurf represents an average proportion of the inorganic fine particles present in a near-surface region of the toner base particle, and Xtotal represents an average proportion of the inorganic fine particles present in the whole toner base particle), wherein the average proportion Xsurf is an average proportion of the inorganic fine particles present in the toner base particle in a region within 200 nm from the surface thereof. ### Claim 2 (depends on 1) The image forming method according to claim 1, wherein the fixing is conducted using a fixing unit, wherein the fixing unit comprises: a heating roller which is made of a magnetic metal and is heated by electromagnetic induction; a fixing roller disposed in parallel to the heating roller; a toner heating medium formed of an endless strip which is stretched between the heating roller and the fixing roller and which is heated by the heating roller and rotated by the heating roller and the fixing roller; and a pressure roller which is pressed against the fixing roller through the toner heating medium and which is rotated in a direction in which the toner heating medium moves to thereby form a nip portion. ### Claim 3 (depends on 1) The image forming method according to claim 1, wherein a part of the inorganic fine particle is exposed at the toner surface. ### Claim 4 (depends on 1) The image forming method according to claim 1, wherein the inorganic fine particles are made of silica. ### Claim 5 (depends on 4) The image forming method according to claim 4, wherein the silica is an organosol synthesized with wet a method. ### Claim 6 (depends on 4) The image forming method according to claim 4, wherein the content of silicon atoms which are derived from silica and present on the toner base particle surface is 0.5 atomic % by number to 10 atomic % by number, as determined with an X-ray electron spectroscopy (XPS). ### Claim 7 (depends on 1) The image forming method according to claim 1, wherein the average primary particle diameter of the inorganic fine particles is 100 nm or less. ### Claim 8 (depends on 1) The image forming method according to claim 1, wherein the charge control agent is externally added with a wet method. ### Claim 9 (depends on 1) The image forming method according to claim 1, wherein the charge control agent is a fluorine-containing compound. ### Claim 10 (depends on 9) The image forming method according to claim 9, wherein the content of fluorine atoms which are derived from the fluorine-containing compound and present on the toner surface is 2.0 atomic % by number to 15 atomic % by number, as determined with an X-ray electron spectroscopy (XPS). ### Claim 11 (depends on 1) The image forming method according to claim 1, wherein the average circularity of toner is 0.94 to 0.97. ### Claim 12 (depends on 1) The image forming method according to claim 1, wherein a shape factor SF-1 represented by the following equation 1 is 110 to 140, and a shape factor SF-2 represented by the following equation 2 is 120 to 160 SF-1=(MXLNG)2/AREA×Π/4×100 equation 1 where MXLNG represents the maximum length across a two-dimensional projection of a toner particle, and AREA represents the area of the projection SF-2=(PERI)2/AREA×¼Π×100 equation 2 where PERI represents the perimeter of a two-dimensional projection of a toner particle, and AREA represents the area of the projection. ### Claim 13 (depends on 1) The image forming method according to claim 1, wherein the volume average particle diameter of toner (Dv) is 3 μm to 8 μm, and the ratio of the volume average particle diameter (Dv) to the number average particle diameter (Dn), Dv/Dn is 1.00 to 1.40. ### Claim 14 (depends on 1) The image forming method according to claim 1, wherein toner is obtained by dissolving or dispersing in an organic solvent a toner material containing an active hydrogen group-containing compound, and a polymer capable of being reacted with the active hydrogen group-containing compound to prepare a toner solution, emulsifying or dispersing the toner solution in an aqueous medium to prepare a dispersion, causing the active hydrogen group-containing compound and a polymer capable of being reacted with the active hydrogen group-containing compound to react to generate an adhesive base material in particles, and removing the organic solvent. ### Claim 15 (depends on 1) The image forming method according to claim 1, wherein toner is a two component developer containing a carrier.