Conductive member, image forming apparatus, conductive particle and method for manufacturing the same
Conductive particle 10 has conductive carbon black particle (CB) 11 and cover layer 12 . The amount of an insulating resin in conductive particle 10 is from 10 to 50% by mass. The number-average primary particle diameter of CB 11 is from 20 to 60 nm; DBP absorption amount is from 100 to 200 mL/100 g. Cover layer 12 is formed by a phase-inversion emulsification method that contains an insulating resin having an amino group and CB 11 in an oil phase. Conductive particle 10 is used suitably for a conductive agent of an intermediate transfer belt of an image forming apparatus.
1. A conductive member comprising a matrix resin and conductive particles dispersed in the matrix resin, wherein:
a surface resistivity is from 1.0×10 9 to 1.0×10 13 Ω/□;
the conductive particles each have a conductive carbon black particle and a cover layer that is in contact with and covers a surface of the conductive carbon black particle;
a number-average primary particle diameter of the conductive carbon black particle is from 20 to 60 nm;
a dibutylphthalate absorption amount of the conductive carbon black particle is from 100 to 200 mL/100 g;
the cover layer is formed of an insulating resin having an amino group;
the insulating resin is an amine-modified styrene elastomer, a polyamide elastomer, a polyamide, or a polyamideimide; and
an amount of the insulating resin in the conductive particle is from 10 to 50% by mass.
2. The conductive member according to claim 1 , wherein the number-average primary particle diameter of the conductive carbon black particle is from 30 to 50 nm.
3. The conductive member according to claim 1 , wherein the dibutylphthalate absorption amount of the conductive carbon black particle is from 100 to 150 mL/100 g.
4. The conductive member according to claim 1 , wherein a surface resistivity of the insulating resin is 1×10 13 Ω/□ or more.
5. The conductive member according to claim 1 , wherein the insulating resin is the amine-modified styrene elastomer or the polyamide elastomer.
6. The conductive member according to claim 1 , wherein an amount of the conductive particles is from 1 to 50 parts by mass relative to 100 parts by mass of the matrix resin.
7. An image forming apparatus comprising an intermediate transfer belt for transferring a toner image formed on an electrophotographic photoconductor to a recording medium, wherein the intermediate transfer belt is formed of the conductive member according to claim 1 .
8. A conductive particle comprising a conductive carbon black particle and a cover layer that is in contact with and covers a surface of the conductive carbon black particle, wherein:
a number-average primary particle diameter of the conductive carbon black particle is from 20 to 60 nm;
a dibutylphthalate absorption amount of the conductive carbon black particle is from 100 to 200 mL/100 g;
the cover layer is formed of an insulating resin having an amino group;
the insulating resin is an amine-modified styrene elastomer, a polyamide elastomer, a polyamide, or a polyamideimide; and
an amount of the insulating resin in the conductive particle is from 10 to 50% by mass.
9. The conductive particle according to claim 8 , wherein the number-average primary particle diameter of the conductive carbon black particle is from 30 to 50 nm.
10. The conductive particle according to claim 8 , wherein the dibutylphthalate absorption amount of the conductive carbon black particle is from 100 to 150 mL/100 g.
11. The conductive particle according to claim 8 , wherein a surface resistivity of the insulating resin is 1×10 13 Ω/□ or more.
12. The conductive particle according to claim 8 , wherein the insulating resin is the amine-modified styrene elastomer or the polyamide elastomer.
13. A method for manufacturing a conductive particle having a conductive carbon black particle a surface of which is in contact with and covered with a cover layer formed of an insulating resin, comprising:
adding an aqueous medium to a hydrophobic dispersion liquid that is prepared by dissolving an insulating resin in a hydrophobic organic solvent and dispersing conductive carbon black particles, in an amount larger than that of the hydrophobic dispersion liquid to emulsify the aqueous medium and the hydrophobic dispersion liquid; and
distilling away the organic solvent from an emulsion of the hydrophobic dispersion liquid and the aqueous medium to fix the insulating resin to a surface of the conductive carbon black particle, wherein;
a number-average primary particle diameter of the conductive carbon black particle is from 20 to 60 nm;
a dibutylphthalate absorption amount of the conductive carbon black particle is from 100 to 200 mL/100 g; and
the insulating resin is an amine-modified styrene elastomer, a polyamide elastomer, a polyamide, or a polyamideimide.
14. The conductive member according to claim 1 , wherein the cover layer uniformly adheres to the surface of the conductive carbon black particle.
15. The conductive member according to claim 1 , wherein the cover layer is formed by a phase-inversion emulsification method that employs as an oil phase a hydrophobic dispersion liquid containing the conductive carbon black particle dispersed and the insulating resin dissolved.
16. The conductive particle according to claim 8 , wherein the cover layer is formed by a phase-inversion emulsification method that employs as an oil phase a hydrophobic dispersion liquid containing the conductive carbon black particle dispersed and the insulating resin dissolved.
17. The conductive member according to claim 1 , wherein a thickness of the cover layer is from 1 to 10 nm.