Image carrier, process cartridge and image-forming apparatus

1. An image carrier comprising:

a conductive base material; and

a photosensitive layer formed on the base material, wherein

the photosensitive layer includes an undercoat layer formed on the base material, a charge-generating layer formed on the undercoat layer, and a charge-transporting layer which is formed on the charge-generating layer and which is an outermost surface layer,

the charge-transporting layer contains aggregate particles of a fluorine resin in an amount of 4.5% or more and 7.5% or less by weight, each particle of the aggregate particles having a number-averaged particle sphericality represented by Formula (1) of 0.62 or more and 0.7 or less: sphericality=4πA/L 2 (1), where π represents the circular constant, A represents a projection area of each particle of the aggregate particles, and L represents a peripheral length of a projected image of each particle of the aggregate particles, and

the charge-transporting layer has a surface having a center-line average roughness (Ra) of 0.1 μm or more and 0.5 μm or less.

2. The image carrier according to claim 1 , wherein the particles are particles of an ethylene tetrafluoride resin.

3. The image carrier according to claim 1 , wherein the base material is formed of aluminum.

4. The image carrier according to claim 1 , wherein

the undercoat layer prevents light entering the image carrier from being reflected on a surface of the base material,

the charge-generating layer generates a charged carrier by receiving the light, and

the charge-transporting layer transports the charged carrier.

5. The image carrier according to claim 1 , wherein the charge-generating layer is a layer containing phthalocyanine.

6. A process cartridge comprising:

an image carrier having a conductive base material and a photosensitive layer formed on the base material, wherein

the photosensitive layer includes an undercoat layer formed on the base material, a charge-generating layer formed on the undercoat layer, and a charge-transporting layer which is formed on the charge-generating layer and which is an outermost surface layer;

the charge-transporting layer contains aggregate particles of a fluorine resin in an amount of 4.5% or more and 7.5% or less by weight, each particle of the aggregate particles having a number-averaged particle sphericality represented by Formula (1) of 0.62 or more and 0.7 or less: sphericality=4πA/L 2 (1), where it represents the circular constant, A represents a projection area of each particle of the aggregate particles, and L represents a peripheral length of a projected image of each particle of the aggregate particles;

the charge-transporting layer has a surface having a center-line average roughness (Ra) of 0.1 μm or more and 0.5 μm or less; and

an electrostatically charging unit that charges the image carrier by contacting the image carrier.

7. An image-forming apparatus comprising:

an image carrier having a conductive base material and a photosensitive layer formed on the base material, wherein

the photosensitive layer includes an undercoat layer formed on the base material, a charge-generating layer formed on the undercoat layer, and a charge-transporting layer which is formed on the charge-generating layer and which is an outermost surface layer;

the charge-transporting layer contains aggregate particles of a fluorine resin in an amount of 4.5% or more and 7.5% or less by weight, each particle of the aggregate particles having a number-averaged particle sphericality represented by Formula (1) of 0.62 or more and 0.7 or less: sphericality=4πA/L 2 (1), where π represents the circular constant, A represents a projection area of each particle of the aggregate particles, and L represents a peripheral length of a projected image of each particle of the aggregate particles;

the charge-transporting layer has a surface having a center-line average roughness (Ra) of 0.1 μm or more and 0.5 μm or less;

an electrostatically charging unit that charges the image carrier by contacting the image carrier; and

an image-forming unit that forms an electrostatic latent image on the image carrier charged by the electrostatically charging unit and thereby forms a developed image by developing the electrostatic latent image.