Charging member, process cartridge, and image forming apparatus

1. A charging member, comprising:

a substrate; and

an outermost layer that is on the substrate, is in contact with a member to be charged, and contains a cross-linking fluorocarbon siloxane rubber composition,

wherein

the charging member charges the member to be charged by being brought into contact with the member to be charged while a voltage is applied, and

the cross-linking fluorocarbon siloxane rubber composition comprises:

(A) a fluorocarbon polymer having an aliphatic unsaturated group and mainly composed of fluorocarbon siloxane represented by the structural formula (1), (3), or (4) below;

(B) organopolysiloxane and/or fluorocarbon siloxane having two or more silyl groups per molecule, the molar amount of the silyl groups being 1 to 4 times the molar amount of the aliphatic unsaturated group in the fluorocarbon polymer;

(C) a filler; and

(D) a catalyst,

where in the structural formula (I):

R 10 represents an unsubstituted or substituted monovalent hydrocarbon group,

a and e each independently represent 0 or 1,

b and d each independently represent an integer of 1 to 4,

c represents an integer of 0 to 8, and

x represents an integer of 1 or more,

CH 2 ═CH—(X) p -Rf′—(X′) p -CH═CH 2   (3)

CH 2 ═CH—(X) p -Q-Rf′-Q-(X′) p -CH═CH 2   (4)

where in the structural formulas (3) and (4):

X is —CH 2 —, —CH 2 O—, —CH 2 OCH 2 —, or —Y—NR—CO—, wherein Y is —CH 2 — or a group represented by the structural formula (5A) below and R is a hydrogen atom, a methyl group, a phenyl group, or an allyl group,

X′ is —CH 2 —, —OCH 2 —, —CH 2 OCH 2 —, or —CO—NR′—Y′—, wherein Y′ is —CH 2 — or a group represented by the structural formula (5B) below and R′ is a hydrogen atom, a methyl group, a phenyl group, or an allyl group,

Rf′ has a divalent perfluoropolyether structure,

p is independently 0 or 1, and

Q is a divalent hydrocarbon group with 1 to 15 carbon atoms that may have an ether linkage.

2. The charging member according to claim 1 , wherein a gel fraction of the outermost layer is about 50% or more.

3. The charging member according to claim 2 , wherein an elastic layer containing a synthetic rubber is between the substrate and the outermost layer.

4. The charging member according to claim 3 , wherein the elastic layer contains conductive particles.

5. The charging member according to claim 3 , wherein the synthetic rubber is a member selected from the group consisting of polyurethane, silicone rubber, ethylene-propylene-diene copolymer rubber, epichlorohydrin-ethyleneoxide copolymer rubber, epichlorohydrin-ethyleneoxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and a blend rubber of the foregoing.

6. The charging member according to claim 1 , wherein an elastic layer containing a synthetic rubber is between the substrate and the outermost layer.

7. The charging member according to claim 6 , wherein the elastic layer contains conductive particles.

8. The charging member according to claim 6 , wherein the synthetic rubber is a member selected from the group consisting of polyurethane, silicone rubber, ethylene-propylene-diene copolymer rubber, epichlorohydrin-ethyleneoxide copolymer rubber, epichlorohydrin-ethyleneoxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and a blend rubber of the foregoing.

9. A process cartridge comprising at least one unit selected from the group of:

an image carrier;

a charging unit that charges the image carrier;

an exposing unit that forms an electrostatic latent image on the charged image carrier by exposing the image carrier;

a developing unit that forms a toner image by developing the electrostatic latent image with a developer for developing an electrostatic charge image;

a transfer unit that transfers the toner image from the image carrier onto a transfer-receiving body; and

a cleaning unit that removes a toner left on a surface of the image carrier,

wherein a charging member used in the charging unit is the charging member according to claim 1 .

10. The process cartridge according to claim 9 , wherein a gel fraction of the outermost layer is about 50% or more.

11. The process cartridge according to claim 9 , wherein an elastic layer containing a synthetic rubber is between the substrate and the outermost layer.

12. An image forming apparatus, comprising:

a latent image forming unit that contains the charging member of claim 1 and forms a latent image on a latent image carrier using the charging member;

a developing unit that develops the latent image with a developer for developing an electrostatic charge image;

a transfer unit that transfers a developed toner image onto a transfer-receiving body with or without an intermediate transfer body; and

a fixing unit that fixes the toner image formed on the transfer-receiving body.

13. The image forming apparatus according to claim 12 , wherein a gel fraction of the outermost layer is about 50% or more.

14. The image forming apparatus according to claim 12 , wherein an elastic layer containing a synthetic rubber is between the substrate and the outermost layer.