To provide an image forming method for suppressing or preventing disturbance in an image and wrinkles in a sheet under high temperature and high humidity conditions.
The image forming method is carried out by using a fixing apparatus which is equipped with at least a rotatable cylindrical heating roll housing a heating means inside and a pressurizing member, wherein the heating roll and the pressurizing member are disposed to form a pressure contact part continuous and parallel to the rotation axis of the heating roll and axis direction and a recording medium having a unfixed toner image formed on the surface is inserted and passed through the contact pressure part to be heated and pressurized so as to fix the unfixed toner image to the surface of the recording medium. In this method, the nip shape index C defined by formula (1): C=a/b of the contact pressure part is in the range of 0.6 to 0.9, and the bulk density of the toner forming the unfixed toner image is ≤0.5 g/cm3. In formula (1), (a) is the length (center nip width) of the contact pressure part in the direction orthogonal to the rotation axis in a center part along the direction of the rotation axis, and (b) is the length (end nip width) of the contact pressure part in the direction orthogonal to the rotation axis at the ends in the rotation axis direction.
SOYAMA HIDEHIKO
MATSUDA TSUKASA
Kato Kazunori
Katsuichi Nishimoto
Hiroshi Fukuda
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