Fixing belt and method of manufacturing the fixing belt

A rotatable endless fixing belt configured to fix a toner image borne on a recording material to the recording material by heating the toner image, the fixing belt being configured to be nipped by a rotary member disposed outside the fixing belt and a backup member disposed inside the fixing belt, a nip portion being formed between the fixing belt and the rotary member by the fixing belt being nipped by the rotary member and the backup member, the nip portion being a portion in which the toner image is fixed to the recording material, the fixing belt comprising:

• a base body;
• and
• a polyimide layer formed on an inner-circumferential-surface of the base body and configured to slide on the backup member in contact with the backup member,
• wherein the polyimide layer comprises filler having shape anisotropy,
• wherein the polyimide layer comprises a plurality of Benard cells formed on an inner circumferential surface of the polyimide layer and having an average diameter equal to or larger than 50 μm and smaller than 200 μm, and
• wherein an arithmetic average roughness of the inner circumferential surface of the polyimide layer is equal to or larger than 0.20 μm and equal to or smaller than 0.50 μm.

A method of manufacturing a fixing belt that fixes a toner image borne on a recording material to the recording material by heating the toner image, the fixing belt being configured to be nipped by a rotary member disposed outside the fixing belt and a backup member disposed inside the fixing belt, a nip portion being formed between the fixing belt and the rotary member by the fixing belt being nipped by the rotary member and the backup member, the nip portion being a portion in which the toner image is fixed to the recording material, the fixing belt comprising a base body and a polyimide layer formed on an inner-circumferential-surface of the base body and configured to slide on the backup member in contact with the backup member, the method comprising:

• coating an inner circumferential surface of the base body with a solution in which a precursor of the polyimide layer and filler are dispersed in a solvent;
• and
• drying the solvent of the solution that has been applied onto the inner circumferential surface of the base body,
• wherein in the drying, the solvent is dried such that a difference between a first temperature and a second temperature is equal to or larger than 10° C. and equal to or smaller than 30° C., where the first temperature is a temperature of an outer circumferential surface of the base body and the second temperature is an ambient temperature of an inner-circumferential-surface side of the polyimide layer that is lower than the first temperature.