Title of Invention

AN IMAGE FORMING METHOD

Abstract

A toner for developing electrostatic images is constituted as a powdery mixture of toner particles, inorganic fine powder, resin fine particles, and metal oxide particles. The toner has a weight-average particle size of 4 - 12 pm and contains at most 30 % by number of particles having a particle size of at most 3.17 pm. The inorganic fine powder has an average primary particle size of 1 - 50 nm. The resin fine particles have an average particle size of 0.1 - 2 pm and a shape factor SF1 of at least 100 and below 150. The metal oxide particles have an average particle size of 0.3 - 3 pm and a shape factor SF1 of 150 - 250. The toner is effective for preventing toner sticking onto and ununiform abrasion of the electrostatic image-bearing member to allow the formation of high-quality images for along life.

Full Text

ABSTRACT OF THE DISCLOSURE A toner for developing electrostatic images is constituted as a powdery mixture of toner particles, inorganic fine powder, resin fine particles, and metal oxide particles. The toner has a weight-average particle size of 4 - 12 pm and contains at most 30 % by number of particles having a particle size of at most 3.17 pm. The inorganic fine powder has an average primary particle size of 1 - 50 nm. The resin fine particles have an average particle size of 0.1 - 2 van and a shape factor SFl of at least 100 and below 150. The metal oxide particles have an average particle size of 0.3 - 3 pm and a shape factor SFl of 150 - 250. The toner is effective for preventing toner sticking onto and cuneiform abrasion of the electrostatic image-bearing member to allow the formation of high-quality images for a-rating life. WE CLAIM: 1. An image forming method, comprising the steps of charging a surface of an electrostatic image-bearing member, forming an electrostatic image on the electrostatic image-bearing member; developing the electrostatic image with a toner for developing electrostatic images to form a toner image transferring the toner image formed on the electrostatic image-bearing member to a transfer-receiving material, cleaning the surface of the electrostatic image-bearing member after the transfer by abutting a cleaning member thereto, and repeating the above mentioned steps by using the cleaned electrostatic image-bearing member; wherein the toner comprises toner particles, inorganic fine powder, resin fine particles, and metal oxide particles; wherein the toner has a weight-average particle size of 4-12 fxm and contains at most 30% by number of particles having a particle size of at most 3.17 |jam; the inorganic fine powder has an average primary particle size of 1 - 50 nm; the resin fine particles have an average particle size of 0.1 - 2 [im and a shape factor SFl of at least 100 and below 150, and the metal oxide particles have an average particle size of 0.3 - 3 |j,m and a shape factor SFl of 150 -250. 2. The method according to claim 1, wherein the electrostatic image-bearing member is charged with a contact-charging means supplied with a bias voltage. 3. The method according to claim 2, wherein the electrostatic image-bearing member is a photosensitive drum, and the contact-charging means is a charging roller. 4. The method according to claim 1, wherein the resin fine particles have a shape factor SF-1 of at least 115 and below 145, and the metal oxide particles have a shape factor SF-1 of 160 - 230. 5. The method according to claim 1, wherein the resin fine particles have a shape factor SF-2 of at least 110 and below 200, and the metal oxide particles have a shape factor SF-2 of 160 - 300. 6. The method according to claim 1, wherein the resin fine particles have a shape factor SF-2 of at least 120 and below 175, and the metal oxide particles have a shape factor SF-2 of 175 - 270. 7. The method according to claim 1, wherein the inorganic fine powder has a charging polarity identical to that of the toner particles, the resin fine particles have a charging polarity identical to that of the toner particles and a volume resistively of 10 ohm’s, and the metal oxide particles have a charging polarity opposite to that of the toner particles. 8. The method according to claim 1, wherein the inorganic fine powder, the resin fine particles and the metal oxide particles are added in amounts of 0.3 - 3.0 wt. parts, 0.005 - 0.5 wt. parts and 0.05 - 5.0 wt. parts respectively, per 100 wt. parts of the toner particles. 9. The method according to claim 1, wherein the inorganic fine powder, the resin fine particles and the meal oxide particles have specific surface areas of 70 - 300 m^/g, 5.0-20.0 mVg, and 0.5-10.0 m^/g, respectively. 10. The method according to claim 1, wherein the inorganic fine powder comprises hydrophobic silica. 11. The method according to claim 1, wherein the inorganic fine powder has been treated with silicone oil. 12. The method according to claim 1, wherein the resin fine particles comprise a styrene resin or an acrylic resin. 13. The method according to claim 1, wherein the metal oxide particles comprise strontium titanate. 14. The method according to claim 1, wherein the metal oxide particles comprise cerium oxide. 15. The method according to claim 1, wherein the toner particles comprise polymer components characterized by (a) containing substantially no THF (tetrahydrofuran) - insoluble content, (b) containing a THF-soluble content giving a GPC (gel-permeation chromatography) chromatogram showing a main peak in a molecular weight region of 3x10^ - 3x10"*, and a sub peak or shoulder in a molecular weight region of 1x10^ - 3x10^, and (c) having an acid value of at least 1 mgKOH/g. 6. The method according to claim 15, wherein the polymer components comprise a low-molecular weight polymer component having molecular weights of below 5x10^* on the GPC chromatogram and an acid value AvL, and a high molecular weight polymer component having molecular weights of at least 5x10"* and an acid value AVH satisfying AVL >AvH. 17. The method according to claim 16, wherein the acid value AVL of the low-molecular weight polymer component is 21 - 35 mgKOH/g and the acid value AvH of the high molecular weight polymer component is 0.5 -11 mgKOH/g, giving a difference satisfying 10 18. The method according to claim 15, wherein the polymer components provide an acid value/total acid value ratio of at most 0.7. 19. The method according to claim 15, wherein the THF-soluble content of the polymer components provides the GPC chromatogram showing a minimum value in a molecular weight region of at least 3x10"^ and below 1x10^ 20. The method according to claim 1, wherein the toner particles contain a magnetic material. 21. The method according to claim 1, wherein the toner particles contain a silicon-containing magnetic material. 22. An image forming method substantially as herein described with reference to the accompanying drawings.

Documents:

011-mas-1997 abstract-duplicate.pdf

011-mas-1997 abstract.pdf

011-mas-1997 claims-duplicate.pdf

011-mas-1997 claims.pdf

011-mas-1997 correspondence-others.pdf

011-mas-1997 correspondence-po.pdf

011-mas-1997 description (complete)-duplicate.pdf

011-mas-1997 description (complete).pdf

011-mas-1997 drawings.pdf

011-mas-1997 form-2.pdf

011-mas-1997 form-26.pdf

011-mas-1997 form-4.pdf

011-mas-1997 others.pdf

011-mas-1997 petition.pdf