Fixing device
A fixing device includes an endless belt, a rotatable pressing member, a pad member inside of the belt, and a sliding member held by the pad member and sliding on an inner circumferential surface of the belt in a nip. The rotatable pressing member nips and feeds a recording material in the nip in cooperation with the belt and fixes a toner image on the recording material by applying heat and pressure. The sliding member includes a base material layer on which a plurality of projections projecting toward the rotatable pressing member are formed on a side sliding with the belt and a sliding layer provided on an outer surface of the plurality of projections. A leading end of the plurality of projections is a plane and an average roughness (Ra) of the plane satisfies 0.13 μm≤Ra≤1.67 μm.
1. A fixing device comprising:
an endless belt configured to apply heat to a recording material;
a rotatable pressing member contacting an outer circumferential surface of the belt;
a pad member inside of the belt, configured to form a nip portion by nipping and feeding the belt between itself and the rotatable pressing member; and
a sliding member held by the pad member and configured to slide on an inner circumferential surface of the belt in the nip portion,
wherein the rotatable pressing member nips and feeds the recording material in the nip portion in cooperation with the belt and fixes a toner image on the recording material by applying heat and pressure,
wherein the sliding member includes a base material layer on which a plurality of projections projecting toward the rotatable pressing member are formed on a side sliding with the belt and a sliding layer provided on an outer surface of the plurality of projections, and
wherein a leading end of the plurality of projections is a plane and an average roughness (Ra) of the plane satisfies 0.13 μm≤Ra≤1.67 μm.
2. The fixing device according to claim 1 , wherein an average roughness Ra of a side surface of the plurality of projects satisfies 0.13 μm≤Ra≤1.67 μm.
3. The fixing device according to claim 2 , wherein in a surface of a side of the basic material layer on which the sliding layer is provided, an average roughness Ra of a bottom surface of a recessed portion between the plurality of adjacent projections satisfies 0.13 μm≤Ra≤1.67 μm.
4. The fixing device according to claim 1 , wherein between the basic material layer and the sliding layer, an adhesive layer adhering the sliding layer to the basic material layer is provided.
5. The fixing device according to claim 1 , wherein a width Wbc of the plane is 150 μm to 450 μm.
6. The fixing device according to claim 1 , wherein the plurality of projections are disposed over in a feeding direction of the recording material in the nip portion and over a widthwise direction of the recording material crossing the feeding direction in a plurality, respectively, and a distance between centers of adjacent projections in the feeding direction and a distance between centers of adjacent projections in the widthwise direction are not less than 1.4 mm, respectively.
7. The fixing device according to claim 1 , wherein the sliding layer is formed by baking at a high temperature after spray coating of a coating agent to a surface of a side of the basic material layer which slides on the belt, and
wherein a viscosity of the coating agent during spray is not more than 10 Pa·sec at a normal temperature.
8. The fixing device according to claim 1 , wherein the basic material layer is made of a metal, and
wherein the sliding layer is made of a resin.
9. The fixing device according to claim 8 , wherein the sliding layer is made of a fluororesin.
10. The fixing device according to claim 1 , wherein a fixing operation continues in a state in which the plane slides on the inner circumference of the belt.