| 摘要 |
PROBLEM TO BE SOLVED: To provide magnetic toner exhibiting excellent durable developing property and high cleaning property, and at the same time, improving a start-up stripe defect. SOLUTION: The magnetic toner comprises magnetic toner particles and a fatty acid metal salt, and is characterized in that: (1) the surface tension index I of the toner with respect to 45 vol% methanol aqueous solution, which is measured by a capillary suction time method and calculated according to formula (I):I=P<SB>α</SB>/(A×B×10<SP>6</SP>) is 5.0×10<SP>-3</SP>N/m or more and 1.0×10<SP>-1</SP>N/m or less, wherein I represents a surface tension index (N/m) of the magnetic toner, P<SB>α</SB>represents a capillary pressure (N/m<SP>2</SP>) of the magnetic toner with respect to a 45 vol% methanol aqueous solution, "A" represents a specific surface area (m<SP>2</SP>/g) of the magnetic toner, and "B" represents a true density (g/cm<SP>3</SP>) of the magnetic toner; (2) the fatty acid metal salt has a median diameter (D50) of 0.15μm or more and 0.65μm or less on a volume basis; and (3) the content of the fatty acid metal salt is 0.02 part by mass or more and 0.5 part by mass or less based on 100 parts by mass of the magnetic toner particles. COPYRIGHT: (C)2011,JPO&INPIT
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