Fixing rotating member, fixing device, electrophotographic image forming apparatus, and method for manufacturing fixing rotating member
A fixing rotating member comprising: a base material and an electro-conductive layer on the base material; the electro-conductive layer extending in a circumferential direction of an outer peripheral surface of the base material, the electro-conductive layer comprising silver, an average crystal grain size of crystals of the silver observed in a cross section along a circumferential direction of the electro-conductive layer being 20 to 200 nm, and the electro-conductive layer having a volume resistivity of 1.0×10 −8 to 8.0×10 −8 Ω·m.
1. A fixing device comprising:
a fixing rotating member; and
an induction heating device that causes the fixing rotating member to generate heat by induction heating,
wherein the fixing rotating member comprises a base material and an electro-conductive layer on the base material,
wherein the electro-conductive layer comprises heat generating rings, which are electrically connected in a circumferential direction of an outer peripheral surface of the base material and electrically divided in a longitudinal direction, and which are aligned in the longitudinal direction,
wherein the electro-conductive layer comprises silver,
wherein an average crystal grain size of crystals of the silver observed in a cross section along a circumferential direction of the electro-conductive layer is 20 to 200 nm,
wherein the electro-conductive layer has a volume resistivity of 1.0×10 −8 to 8.0×10 −8 Ω·m, and
wherein the induction heating device comprises:
an excitation coil that is arranged inside the fixing rotating member and has a helical portion with a helical axis substantially parallel to a direction along a rotation axis of the fixing rotating member, the excitation coil serving to form an alternating magnetic field for causing the electro-conductive layer to generate heat by electromagnetic induction; and
a magnetic core arranged in the helical portion and extending in the rotation axis direction so as not to form a loop outside the fixing rotating member, the magnetic core serving to guide lines of magnetic force of the alternating magnetic field,
wherein the magnetic core is made of a ferromagnetic material, and
wherein heat is mainly generated in the electro-conductive layer by an induced current induced by lines of magnetic force that exit from one longitudinal end of the magnetic core, pass outside the electro-conductive layer, and return to the other longitudinal end of the magnetic core.
2. The fixing device according to claim 1 , wherein the fixing rotating member is a fixing belt having endless belt shape.
3. The fixing device according to claim 1 , wherein the electro-conductive layer has a maximum thickness of 4 μm or less.
4. The fixing device according to claim 1 , wherein a content of the silver in the electro-conductive layer is 99.0% by mass or more.
5. The fixing device according to claim 1 , wherein the electro-conductive layer comprises a sintered body of silver nanoparticles.
6. The fixing device according to claim 1 , wherein a coefficient of variation of the crystal grain size of the silver in the electro-conductive layer is less than 0.60.
7. The fixing device according to claim 1 , wherein:
the fixing rotating member comprises a resin layer on a side of the electro-conductive layer opposite to a side facing the base material;
the base material contains a first heat-resistant resin; and
the resin layer contains a second heat-resistant resin.
8. The fixing device according to claim 7 , wherein the first heat-resistant resin is a polyimide or a polyamideimide, and
wherein the second heat-resistant resin is a polyimide or a polyamideimide.
9. An electrophotographic image forming apparatus, the electrophotographic image forming apparatus comprising:
an image bearing member that bears a toner image;
a transfer device that transfers the toner image onto a recording material; and
a fixing device that fixes the transferred toner image onto the recording material,
wherein the fixing device comprises a fixing rotating member and an induction heating device that causes the fixing rotating member to generate heat by induction heating,
wherein the fixing rotating member comprises a base material and an electro-conductive layer on the base material,
wherein the electro-conductive layer comprises heat generating rings, which are electrically connected in a circumferential direction of an outer peripheral surface of the base material and electrically divided in a longitudinal direction, and which are aligned in the longitudinal direction,
wherein the electro-conductive layer comprises silver,
wherein an average crystal grain size of crystals of the silver observed in a cross section along a circumferential direction of the electro-conductive layer is 20 to 200 nm, and
wherein the electro-conductive layer has a volume resistivity of 1.0×10 −8 to 8.0×10 −8 Ω·m.