# US 12,601,996 B2 · Fixing member, fixing device, 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 12,601,996 B2 - Document ID: US12601996B2 - Status: Granted - Kind: B2 - Application number: 18/814,562 - Filed: 2024-08-25 - Published: 2025-07-17 - Granted: 2026-04-14 - Earliest claimed: 2024-01-17 - Assignees: FUJIFILM Business Innovation Corp. - Applicants: FUJIFILM Business Innovation Corp. - Inventors: Kenji Kajiwara; Hiroaki Tanaka; Ryohei Yoshikawa; Taiki Nagamatsu; Tomotake Inagaki; Masayuki Seko - Web page: https://patentgrep.com/patent/US12601996B2 ## CPC - G03G 15/2057: {relating to the chemical composition of the heat element and layers thereof} - G03G 15/206: {Structural details or chemical composition of the pressure elements and layers thereof} - G03G 15/2064: {combined with pressure} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A molded body contains a resin and a filler dispersed in the resin, in which, in a case where a Martens hardness is measured at 10 locations within a region of 50 mm square on a maximum surface of the molded body, a difference between a maximum value and a minimum value of the Martens hardness is 200 N/mm2 or more. ## Claims ### Claim 1 A fixing member, comprising: a molded body, including: a resin; and a filler mixed with the resin, wherein a difference between a maximum value and a minimum value of a Martens hardness at 10 locations within a region of 50 mm square on a maximum surface of the molded body is 200 N/mm2 or more and 500 N/mm2 or less. ### Claim 2 (depends on 1) The fixing member according to claim 1, wherein the filler includes two or more types of fillers having different shapes from each other or two or more types of fillers having different surface properties from each other. ### Claim 3 (depends on 1) The fixing member according to claim 1, wherein the filler includes a first filler having a first functional group on a surface and a second filler having a second functional group different from the first functional group on the surface. ### Claim 4 (depends on 1) The fixing member according to claim 1, wherein an average value of aspect ratios of the filler is 10 or more and 500 or less. ### Claim 5 (depends on 1) The fixing member according to claim 1, wherein a volume proportion of the filler in the molded body is 10% by volume or more and 50% by volume or less. ### Claim 6 (depends on 1) The fixing member according to claim 1, wherein the filler includes at least one of carbon material, silicon carbide, metal nitride, and metal oxide. ### Claim 7 (depends on 1) The fixing member according to claim 1, wherein an average value of a major axis length of the filler is 3 μm or more and 200 μm or less. ### Claim 8 (depends on 1) A fixing device comprising: a first rotating body; and a second rotating body disposed in contact with an outer surface of the first rotating body, wherein at least one of the first rotating body or the second rotating body is the fixing member according to claim 1, and a recording medium on which a toner image is formed on a surface is passed through a contact portion between the first rotating body and the second rotating body to fix the toner image. ### Claim 9 (depends on 8) An image forming apparatus comprising: an image holding body; a charging device that charges a surface of the image holding body; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image holding body; a developing device that develops the electrostatic latent image formed on the surface of the image holding body with a developer containing a toner to form a toner image; a transfer device that transfers the toner image onto a surface of a recording medium; and the fixing device according to claim 8 that fixes the toner image on the recording medium. ### Claim 10 A fixing member, comprising: a molded body, including: a rubber; and a filler mixed with the rubber, wherein a difference between a maximum value and a minimum value of a Martens hardness at 10 locations within a region of 50 mm square on a maximum surface of the molded body is 5 N/mm2 or more and 30 N/mm2 or less. ### Claim 11 (depends on 10) The fixing member according to claim 10, wherein the filler includes two or more types of fillers having different shapes from each other or two or more types of fillers having different surface properties from each other. ### Claim 12 (depends on 10) The fixing member according to claim 10, wherein the filler includes a first filler having a first functional group on a surface and a second filler having a second functional group different from the first functional group on the surface. ### Claim 13 (depends on 10) The fixing member according to claim 10, wherein an average value of aspect ratios of the filler is 10 or more and 500 or less. ### Claim 14 (depends on 10) The fixing member according to claim 10, wherein a volume proportion of the filler in the molded body is 10% by volume or more and 50% by volume or less. ### Claim 15 (depends on 10) A fixing device comprising: a first rotating body; and a second rotating body disposed in contact with an outer surface of the first rotating body, wherein at least one of the first rotating body or the second rotating body is the fixing member according to claim 10, and a recording medium on which a toner image is formed on a surface is passed through a contact portion between the first rotating body and the second rotating body to fix the toner image. ### Claim 16 (depends on 15) An image forming apparatus comprising: an image holding body; a charging device that charges a surface of the image holding body; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image holding body; a developing device that develops the electrostatic latent image formed on the surface of the image holding body with a developer containing a toner to form a toner image; a transfer device that transfers the toner image onto a surface of a recording medium; and the fixing device according to claim 15 that fixes the toner image on the recording medium. ### Claim 17 (depends on 10) The fixing member according to claim 10, wherein the filler includes at least one of carbon material, silicon carbide, metal nitride, and metal oxide. ### Claim 18 (depends on 10) The fixing member according to claim 10, wherein an average value of a major axis length of the filler is 3 μm or more and 200 μm or less.