Electrophotographic photoreceptor, process cartridge, and image forming apparatus
An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer disposed on the conductive substrate. An outermost surface layer of the electrophotographic photoreceptor contains a fluorine-based graft polymer and a fluorine-containing resin particle. The fluorine-based graft polymer includes at least a first structural unit that does not have an acidic group with a pKa of 3 or less but has a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having the acidic group with a pKa of 3 or less.
1. An electrophotographic photoreceptor comprising:
a conductive substrate; and
a photosensitive layer disposed on the conductive substrate, wherein
an outermost surface layer of the electrophotographic photoreceptor contains a fluorine-based graft polymer and a fluorine-containing resin particle, and
the fluorine-based graft polymer includes at least a first structural unit that does not have an acidic group with a pKa of 3 or less but has a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having the acidic group with a pKa of 3 or less.
2. The electrophotographic photoreceptor according to claim 1 , wherein the acidic group with a pKa of 3 or less includes an acidic group (Ac) which is at least one selected from the group consisting of a sulfo group, a phosphate group, a phosphonate group, and a fluorinated alkyl carboxy group.
3. The electrophotographic photoreceptor according to claim 2 , wherein a number of moles of the acidic group with a pKa of 3 or less per 1 g of the fluorine-containing resin particle is 0.2 μmol/g or more and 5 μmol/g or less.
4. The electrophotographic photoreceptor according to claim 2 , wherein a number of moles of the acidic group (Ac) per 1 g of the fluorine-containing resin particle is 0.2 μmol/g or more and 5 μmol/g or less.
5. The electrophotographic photoreceptor according to claim 1 , wherein a number of moles of the acidic group with a pKa of 3 or less per 1 g of the fluorine-containing resin particle is 0.2 μmol/g or more and 5 μmol/g or less.
6. The electrophotographic photoreceptor according to claim 1 , wherein the macromonomer includes at least one selected from the group consisting of a poly(meth)acrylate having a radical-polymerizable group at one end and polystyrene having a radical-polymerizable group at one end.
7. The electrophotographic photoreceptor according to claim 1 , wherein the first structural unit is a structural unit represented by general formula (1) below, the second structural unit is a structural unit represented by general formula (2) below, and the third structural unit is a structural unit represented by general formula (3) below:
where, in general formula (1), R 1 represents a hydrogen atom or an alkyl group, and Rf represents an organic group having a fluorine atom; in general formula (2), n represents an integer of 2 or more, q represents an integer of 1 or more, R 2 and R 3 each independently represent a hydrogen atom or an alkyl group, Y represents a substituted or unsubstituted alkylene group, —O—, —NH—, —S—, —C(═O)—, a divalent linking group obtained by combining any of these, or a single bond, and Z represents a group represented by general formula (2A) or (2B) below; in general formula (3), L represents a substituted or unsubstituted alkylene group, —O—, —C(═O)—, —NR 10 —, —C 6 H 4 —, a divalent linking group obtained by combining any of these, or a single bond, Q represents a sulfo group, a phosphonate group, a phosphate group, or a fluorinated alkyl carboxy group, and R 6 represents a hydrogen atom, a halogen atom, or an alkyl group; and R 10 represents a hydrogen atom or a substituted or unsubstituted alkyl group;
where, in general formula (2A), R 4 represents a substituted or unsubstituted alkyl group or a mono- or poly-alkyleneoxy chain, and * represents a site bound to a carbon atom; and in general formula (2B), Ra to Re each independently represent a hydrogen atom, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms, and * represents a site bound to a carbon atom.
8. The electrophotographic photoreceptor according to claim 1 , wherein a content of the fluorine-based graft polymer relative to 100 parts by mass of the fluorine-containing resin particle is 0.5 parts by mass or more and 10 parts by mass or less.
9. The electrophotographic photoreceptor according to claim 1 , wherein the fluorine-containing resin particle contains polytetrafluoroethylene.
10. The electrophotographic photoreceptor according to claim 1 , wherein a number of carboxy groups in the fluorine-containing resin particle is 0 or more and 30 or less per 10 6 carbon atoms.
11. The electrophotographic photoreceptor according to claim 10 , wherein the number of carboxy groups in the fluorine-containing resin particle is 0 or more and 20 or less per 10 6 carbon atoms.
12. The electrophotographic photoreceptor according to claim 1 , wherein an amount of perfluorooctanoic acid relative to a mass of the fluorine-containing resin particle is 0 ppb or more and 25 ppb or less.
13. The electrophotographic photoreceptor according to claim 12 , wherein the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particle is 0 ppb or more and 20 ppb or less.
14. The electrophotographic photoreceptor according to claim 1 , wherein the outermost surface layer contains a hole-transporting material.
15. A process cartridge detachably attachable to an image forming apparatus, the process cartridge comprising:
the electrophotographic photoreceptor according to claim 1 .
16. An image forming apparatus comprising:
the electrophotographic photoreceptor according to claim 1 ;
a charging unit that charges a surface of the electrophotographic photoreceptor;
an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;
a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor by using a developer that contains a toner to form a toner image; and
a transfer unit that transfers the toner image onto a surface of a recording medium.
17. An electrophotographic photoreceptor comprising:
a conductive substrate; and
a photosensitive layer disposed on the conductive substrate, wherein
an outermost surface layer of the electrophotographic photoreceptor contains a fluorine-based graft polymer and a fluorine-containing resin particle, and
the fluorine-based graft polymer includes at least a first structural unit that does not have an acidic group (Ac) which is at least one selected from the group consisting of a sulfo group, a phosphate group, a phosphonate group, and a fluorinated alkyl carboxy group but has a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having the acidic group (Ac).
18. The electrophotographic photoreceptor according to claim 17 , wherein a number of moles of the acidic group (Ac) per 1 g of the fluorine-containing resin particle is 0.2 μmol/g or more and 5 μmol/g or less.