Charging member and electrophotographic apparatus using the same

Claim 2

A charging member comprising a surface layer, which comprises a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 3

A member according to claim 1, wherein the surface layer has a volume resistivity of 10 6 to 10 12 ohm.cm.

Claim 4

A member according to claim 1, which comprises a base layer and the surface layer disposed thereon; the surface layer having a volume resistivity which is higher than that of the base layer.

Claim 5

A member according to claim 3, wherein the base layer has a volume resistivity of 10 0 to 10 11 ohm.cm.

Claim 6

A member according to claim 1, wherein the raw material has a molar ratio between the isocyanate group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦1.5.

Claim 7

A member according to claim 1, wherein the surface layer has a thickness of 1-500 microns.

Claim 8

A charging member comprising a base layer and a surface layer disposed thereon; said base layer having a volume resistivity in the range of 10 0 -10 11 ohm.cm which is smaller than that of the surface layer; said surface layer having volume resistivity in the range of 10 6 -10 12 ohm cm and comprising a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 9

A charging member comprising a base layer and a surface layer disposed thereon; said base layer having a volume resistivity in the range of 10 0 -10 11 ohm.cm which is smaller than that of the surface layer; said surface layer having volume resistivity in the range of 10 6 -10 12 ohm cm and comprising a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 10

A member according to claim 7, wherein the raw material has a molar ratio between the isocyanate group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦1.5.

Claim 13

An electrophotographic apparatus comprising a photosensitive member, latent image-forming means for forming a latent image on the photosensitive member, means for developing the latent image to form a developed image, and means for transferring the developed image to a transfer material; said latent image-forming means comprising a charging member disposed in contact with the photosensitive member; said charging member comprising a surface layer which comprises a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 14

An electrophotographic apparatus comprising a photosensitive member, latent image-forming means for forming a latent image on the photosensitive member, means for developing the latent image to form a developed image, and means for transferring the developed image to a transfer material; said latent image-forming means comprising a charging member disposed in contact with the photosensitive member; said charging member comprising a surface layer which comprises a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 15

A facsimile comprising an electrophotographic apparatus and receiving means for receiving image information from a remote terminal; said electrophotographic apparatus comprising a photosensitive member, latent image-forming means for forming a latent image on the photosensitive member, means for developing the latent image to form a developed image, and means for transferring the developed image to a transfer material; said latent image-forming means comprising a charging member disposed in contact with the photosensitive member; said charging member comprising a surface layer which comprises a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.

Claim 16

A facsimile comprising an electrophotographic apparatus and receiving means for receiving image information from a remote terminal; said electrophotographic apparatus comprising a photosensitive member, latent image-forming means for forming a latent image on the photosensitive member, means for developing the latent image to form a developed image, and means for transferring the developed image to a transfer material; said latent image-forming means comprising a charging member disposed in contact with the photosensitive member; said charging member comprising a surface layer which comprises a polyurethane resin prepared from a raw material for polyurethane containing an isocyanate group and a hydroxyl group; the raw material having a molar ratio between the isocyanate (NCO) group and hydroxyl group satisfying the following relationship: 1.0<(mol of NCO group)/(mol of OH group)≦2.0.