Electrophotographic photoreceptor, process cartridge and image forming apparatus

1. An electrophotographic photoreceptor comprising at least a photosensitive layer on a conductive support, the photosensitive layer having a surface layer, the surface layer comprising:

fluororesin particles, and

a fluorocarbon comb graft polymer including a repeating unit derived from a monomer having a fluoroalkyl group having 1 to 8 carbon atoms and a repeating unit derived from a macromonomer produced using a phosphonium salt compound,

wherein the surface layer contains phosphorus in an amount from 1 ppm to 5 ppm, the phosphorus being derived from the phosphonium salt compound used to produce the macromonomer.

2. The electrophotographic photoreceptor of claim 1 , wherein the macromonomer comprises a polymer or a copolymer of an acrylic acid ester, a methacrylic acid ester, or a styrene compound.

3. The electrophotographic photoreceptor of claim 1 , wherein the phosphonium salt compound is selected from the group consisting of a triphenylphosphonium salt compound, a tetraphenylphosphonium salt compound, a tributylphosphonium salt compound, and a tetrabutylphosphonium salt compound.

4. The electrophotographic photoreceptor of claim 1 , wherein a content of fluorine in the fluorocarbon comb graft polymer is from 10% by weight to 40% by weight.

5. The electrophotographic photoreceptor of claim 1 , wherein a content of fluorine in the fluorocarbon comb graft polymer is from 10% by weight to 30% by weight.

6. The electrophotographic photoreceptor of claim 1 , wherein a number average molecular weight of the fluorocarbon comb graft polymer is from 5,000 to 20,000.

7. The electrophotographic photoreceptor of claim 1 , wherein a number average molecular weight of the fluorocarbon comb graft polymer is from 6,000 to 15,000.

8. The electrophotographic photoreceptor of claim 1 , wherein the fluorocarbon comb graft polymer is contained in an amount of 0.5% by weight to 5% by weight with respect to a weight of the fluororesin particles.

9. The electrophotographic photoreceptor of claim 1 , wherein the fluorocarbon comb graft polymer contains a repeating unit represented by the following Structural Formula A and a repeating unit represented by the following Structural Formula B:

wherein in Structural Formulae A and B,

l, m, and n each independently represent an integer of 1 or more;

p, q, r, and s each independently represent 0 or an integer of 1 or more;

t represents an integer of 1 to 7;

R 1 , R 2 , R 3 , and R 4 each independently represent a hydrogen atom or an alkyl group;

X represents an alkylene group, a halogen-substituted alkylene group, —S—, —O—, —NH—, or a single bond;

Y represents an alkylene group, a halogen-substituted alkylene group, —(C z H 2z-1 (OH))—or a single bond; and

z represents an integer of 1 or more.

10. A process cartridge that is detachably attached to an image forming apparatus and comprises the electrophotographic photoreceptor of claim 1 .

11. An image forming apparatus comprising:

the electrophotographic photoreceptor of claim 1 ;

a developing unit that develops an electrostatic latent image formed on the electrophotographic photoreceptor with an electrostatic latent image developer to form a toner image;

a transfer unit that transfers the toner image formed on the electrophotographic photoreceptor onto a receiving body; and

a fixing unit that fixes the transferred toner image on the receiving body.

12. The image forming apparatus of claim 11 , wherein a content of fluorine in the fluorocarbon comb graft polymer is from 10% by weight to 40% by weight.

13. The image forming apparatus of claim 11 , wherein the fluorocarbon comb graft polymer contains a repeating unit represented by the following Structural Formula A and a repeating unit represented by the following Structural Formula B:

wherein in Structural Formulae A and B,

l, m, and n each independently represent an integer of 1 or more;

p, q, r, and s each independently represent 0 or an integer of 1 or more;

t represents an integer of 1 to 7;

R 1 , R 2 , R 3 , and R 4 each independently represent a hydrogen atom or an alkyl group;

X represents an alkylene group, a halogen-substituted alkylene group, —S—, —O—, —NH—, or a single bond;

Y represents an alkylene group, a halogen-substituted alkylene group, —(C z H 2z-1 (OH))—or a single bond; and

z represents an integer of 1 or more.

14. The electrophotographic photoreceptor of claim 1 , wherein the surface layer comprises the phosphorus derived from the phosphonium salt compound in an amount of from 1 ppm to 4 ppm.