Image heating apparatus, pressure roller to be used in the image heating apparatus, and manufacturing method for the pressure roller

A pressure roller to be used in an image heating apparatus for heating a toner image formed on a recording material, comprising:

• a metal core;
• a rubber layer;
• and
• a resin tube layer serving as a surface layer, wherein:
• the rubber layer comprises
• a solid rubber layer having a thermal conductivity of 0.16 W/m·K or more and 0.40 W/m·K or less in a thickness direction of the solid rubber layer, and
• a self-bonded silicone rubber layer provided between the solid rubber layer and the resin tube layer, the self-bonded silicone rubber layer having a thickness of 0.5 mm or more and 5.0 mm or less;
• and
• the self-bonded silicone rubber layer contains needle-shaped fillers at 5 vol % or more and 40 vol % or less, and has a thermal conductivity of 2.5 W/m·K or more in an axial direction of the pressure roller, the needle-shaped fillers having an average length of 0.05 mm or more and 1 mm or less and a thermal conductivity of 500 W/m·K or more in an axial direction of the needle-shaped filler.

A manufacturing method for a pressure roller to be used in an image heating apparatus,

• the pressure roller comprising:
• a metal core;
• a resin tube layer serving as a surface layer;
• a solid rubber layer having a thermal conductivity of 0.16 W/m·K or more and 0.40 W/m·K or less in a thickness direction of the solid rubber layer;
• and
• a self-bonded silicone rubber layer provided between the solid rubber layer and the resin tube layer, the self-bonded silicone rubber layer contains needle-shaped fillers at 5 vol % or more and 40 vol % or less, and has a thermal conductivity of 2.5 W/m·K or more in an axial direction of the pressure roller, the needle-shaped fillers having an average length of 0.05 mm or more and 1 mm or less and a thermal conductivity of 500 W/m·K or more in an axial direction of the needle-shaped filler,
• the manufacturing method comprising:
• placing the metal core provided with the solid rubber layer at a center of a molding die having a cylindrical inner surface;
• placing the resin tube layer on the inner surface of the molding die;
• injecting liquid addition type silicone rubber containing an adhesion-imparting agent and the needle-shaped fillers between the resin tube layer and the metal core provided with the solid rubber layer;
• and
• hardening the liquid addition type silicone rubber and bonding the resin tube layer and the liquid addition type silicone rubber together by an action of the adhesion-imparting agent.