US 12,174,583 B2
Electrostatic charge image developing carrier, electrostatic charge image developer, process cartridge, image forming apparatus and image forming method
Takuro Watanabe, Minamiashigara (JP); Kazutsuna Sasaki, Minamiashigara (JP); Yosuke Tsurumi, Minamiashigara (JP); Yasuo Kadokura, Minamiashigara (JP); and Karin Sakai, Minamiashigara (JP)
Assigned to FUJIFILM Business Innovation Corp., Tokyo (JP)
Filed by FUJIFILM Business Innovation Corp., Tokyo (JP)
Filed on Aug. 24, 2021, as Appl. No. 17/410,051.
Claims priority of application No. 2021-049113 (JP), filed on Mar. 23, 2021.
Prior Publication US 2022/0308485 A1, Sep. 29, 2022
Int. Cl. G03G 9/083 (2006.01)
CPC G03G 9/0839 (2013.01) [G03G 9/0834 (2013.01); G03G 9/0836 (2013.01); G03G 9/0837 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An electrostatic charge image developing carrier comprising:
a magnetic particle; and
a coating resin layer that covers the magnetic particle and contains a silica particle as an internal additive,
wherein a ratio of Si on a surface of the coating resin layer, determined by an X-ray photoelectron spectroscopy (XPS), is 6 atom % or more and 12 atom % or less;
an average particle diameter of the silica particle is 5 nm or more and 70 nm or less;
a content of the silica particle is 25 mass % or more and 45 mass % or less relative to a total mass of the coating resin layer;
an average thickness of the coating resin layer is 0.6 μm or more and 1.4 μm or less; and
an average length RSm of a roughness curve element of a surface of the carrier is 0.5 μm or more and 0.8 μm or less;
an arithmetic average height Ra of a roughness curve of the surface of the carrier is 0.1 μm or more and 1.0 μm or less; and
the arithmetic average height Ra of the roughness curve of the surface of the carrier is different from an arithmetic average height of a roughness curve of a surface of the magnetic particle.