Toner for developing electrostatic image, apparatus unit and image forming method

• US 5,712,073 A
• Filed: 12/31/1996
• Issued: 01/27/1998
• Est. Priority Date: 01/10/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Katada, Masaichiro, Kasuya, Takashige, Kobori, Takakuni
• Primary Examiner(s): MARTIN, ROLAND E
• Application Number:
  US08/777,241
• Time in Patent Office: 392 Days
• Field of Search: 430/110, 430/111
• US Class Current: 430/108.4
• CPC Class Codes: G03G 9/0819 characterised by the dimensions of the particles
• CPC Class Codes: G03G 9/09708 Inorganic compounds
• CPC Class Codes: G03G 9/09733 Organic compounds G03G9/08782 takes precedence

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 μm and contains at most 30% by number of particles having a particle size of at most 3.17 μm. 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 μm 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 μm 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 a long life.

Claims

1. A toner for developing electrostatic images, comprising:

toner particles said inorganic fine powder being different from said metal oxide particles, inorganic fine powder, resin fine particles, and metal oxide particles;

wherein

the toner has a weight-average particle size of 4-12 μ

m and contains at most 30% by number of particles having a particle size of at most 3.17 μ

m;

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 μ

m and a shape factor SF1 of at least 100 and below 150, and

the metal oxide particles have an average particle size of 0.3-3 μ

m and a shape factor SF1 of 150-250.

2. The toner 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.

3. The toner 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.

4. The toner 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.

5. The toner 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 resistivity of 10⁷ -10¹⁴ ohm.cm, and the metal oxide particles have a charging polarity opposite to that of the toner particles.

6. The toner 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.

7. The toner according to claim 1, wherein the inorganic fine powder, the resin fine particles and the metal oxide particles have specific surface areas of 70-300 m² /g, 5.0-20.0 m² /g, and 0.5-10.0 m² /g, respectively.

8. The toner according to claim 1, wherein the inorganic fine powder comprises hydrophobic silica.

9. The toner according to claim 1, wherein the inorganic fine powder has been treated with silicone oil.

10. The toner according to claim 1, wherein the resin fine particles comprise a styrene resin or an acrylic resin.

11. The toner according to claim 1, wherein the metal oxide particles comprise strontium titanate.

12. The toner according to claim 1, wherein the metal oxide particles comprise cerium oxide.

13. The toner 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 3×

10³ -3×

10⁴, and a sub-peak or shoulder in a molecular weight region of 1×

10⁵ -3×

10⁶, and

(C) having an acid value of at least 1 mgKOH/g.

14. The toner according to claim 13, wherein the polymer components include a low-molecular weight polymer component having molecular weights of below 5×

10⁴ on the GPC chromatogram and an acid value A_VL, and a high-molecular weight polymer component having molecular weights of at least 5×

10⁴ and an acid value A_VH satisfying A_VL >

A_VH.

15. The toner according to claim 14, wherein the acid value A_VL of the low-molecular weight polymer component is 21-35 mgKOH/, and the acid value A_VH of the high-molecular weight polymer component is 0.5-11 mgKOH/g, giving a difference satisfying 10≧

(A_VL -A_VH 0≧

27.

16. The toner according to claim 14, wherein the polymer components provide an acid value/total acid value ratio of at most 0.7.

17. The toner according to claim 13, 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 3×

10⁴ and below 1×

10⁵.

18. The toner according to claim 1, wherein the toner particles contain a magnetic material.

19. The toner according to claim 1, wherein the toner particles contain a silicon-containing magnetic material.

20. An apparatus unit, comprising:

an electrostatic image-bearing member, and developing means for developing an electrostatic image formed on the electrostatic image-bearing member with a toner contained therein;

the electrostatic image-bearing member and the developing means being integrally assembled to form a unit, which is detachably mountable to a main assembly of the image forming apparatus;

wherein the toner comprises toner particles, inorganic fine powder, resin fine particles, and metal oxide particles said inorganic fine powder being different from said metal oxide particles;

wherein

the toner has a weight-average particle size of 4-12 μ

m and contains at most 30% by number of particles having a particle size of at most 3.17 μ

m;

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 μ

m and a shape factor SF1 of at least 100 and below 150, and

the metal oxide particles have an average particle size of 0.3-3 μ

m and a shape factor SF1 of 150-250.

21. The apparatus unit according to claim 20, wherein the electrostatic image-bearing member is a photosensitive drum, and the photosensitive drum is provided with a contact-charging means.

22. The apparatus unit according to claim 21, wherein the contact-charging means is a charging roller.

23. The apparatus unit according to claim 21, wherein the electrostatic image-bearing member is provided with a cleaning means.

24. The apparatus unit according to claim 23, wherein the cleaning means is a blade cleaning means.

25. The apparatus unit according to claim 20, 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.

26. The apparatus unit according to claim 20, 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.

27. The apparatus unit according to claim 20, 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.

28. The apparatus unit according to claim 20, 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 resistivity of 10⁷ -10¹⁴ ohm.cm, and the metal oxide particles have a charging polarity opposite to that of the toner particles.

29. The apparatus unit according to claim 20, 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.

30. The apparatus unit according to claim 20, wherein the inorganic fine powder, the resin fine particles and the metal oxide particles have specific surface areas of 70-300 m² /g, 5.0-20.0 m² /g, and 0.5-10.0 m² /g, respectively.

31. The apparatus unit according to claim 20, wherein the inorganic fine powder comprises hydrophobic silica.

32. The apparatus unit according to claim 20, wherein the inorganic fine powder has been treated with silicone oil.

33. The apparatus unit according to claim 20, wherein the resin fine particles comprise a styrene resin or an acrylic resin.

34. The apparatus unit according to claim 20, wherein the metal oxide particles comprise strontium titanate.

35. The apparatus unit according to claim 20, wherein the metal oxide particles comprise cerium oxide.

36. The apparatus unit according to claim 20, 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 3×

10³ -3×

10⁴, and a sub-peak or shoulder in a molecular weight region of 1×

10⁵ -3×

10⁶, and

(c) having an acid value of at least 1 mgKOH/g.

37. The apparatus unit according to claim 36, wherein the polymer components include a low-molecular weight polymer component having molecular weights of below 5×

10⁴ on the GPC chromatogram and an acid value A_VL, and a high-molecular weight polymer component having molecular weights of at least 5×

10⁴ and an acid value A_VH satisfying A_VL >

A_VH.

38. The apparatus unit according to claim 37, wherein the acid value A_VL of the low-molecular weight polymer component is 21-35 mgKOH/, and the acid value A_VH of the high-molecular weight polymer component is 0.5-11 mgKOH/g, giving a difference satisfying 10≧

(A_VL -A_VH 0≧

27.

39. The apparatus unit according to claim 36, wherein the polymer components provide an acid value/total acid value ratio of at most 0.7.

40. The apparatus unit according to claim 36, 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 3×

10⁴ and below 1×

10⁵.

41. The apparatus unit according to claim 20, wherein the toner particles contain a magnetic material.

42. The apparatus unit according to claim 20, wherein the toner particles contain a silicon-containing magnetic material.

43. 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 said inorganic fine powder being different from said metal oxide particles;

wherein

the toner has a weight-average particle size of 4-12 μ

m and contains at most 30% by number of particles having a particle size of at most 3.17 μ

m;

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 μ

m and a shape factor SF1 of at least 100 and below 150, and

the metal oxide particles have an average particle size of 0.3-3 μ

m and a shape factor SF1 of 150-250.

44. The method according to claim 43, wherein the electrostatic image-bearing member is charged with a contact-charging means supplied with a bias voltage.

45. The method according to claim 44, wherein the electrostatic image-bearing member is a photosensitive drum, and the contact-charging means is a charging roller.

46. The method according to claim 43, 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.

47. The method according to claim 43, 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.

48. The method according to claim 43, 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.

49. The method according to claim 43, 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 resistivity of 10⁷ -10¹⁴ ohm.cm, and the metal oxide particles have a charging polarity opposite to that of the toner particles.

50. The method according to claim 43, 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.

51. The method according to claim 43, wherein the inorganic fine powder, the resin fine particles and the metal oxide particles have specific surface areas of 70-300 m² /g, 5.0-20.0 m² /g, and 0.5-10.0 m² /g, respectively.

52. The method according to claim 43, wherein the inorganic fine powder comprises hydrophobic silica.

53. The method according to claim 43, wherein the inorganic fine powder has been treated with silicone oil.

54. The method according to claim 43, wherein the resin fine particles comprise a styrene resin or an acrylic resin.

55. The method according to claim 43, wherein the metal oxide particles comprise strontium titanate.

56. The method according to claim 43, wherein the metal oxide particles comprise cerium oxide.

57. The method according to claim 43, 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 3×

10³ -3×

10⁴, and a sub-peak or shoulder in a molecular weight region of 1×

10⁵ -3×

10⁶, and

(c) having an acid value of at least 1 mgKOH/g.

58. The method according to claim 57, wherein the polymer components include a low-molecular weight polymer component having molecular weights of below 5×

10⁴ on the GPC chromatogram and an acid value A_VL, and a high-molecular weight polymer component having molecular weights of at least 5×

10⁴ and an acid value A_VH satisfying A_VL >

A_VH.

59. The method according to claim 58, wherein the acid value A_VL of the low-molecular weight polymer component is 21-35 mgKOH/, and the acid value A_VH of the high-molecular weight polymer component is 0.5-11 mgKOH/g, giving a difference satisfying 10≧

(A_VL -A_VH 0≧

27.

60. The method according to claim 57, wherein the polymer components provide an acid value/total acid value ratio of at most 0.7.

61. The method according to claim 57, 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 3×

10⁴ and below 1×

10⁵.

62. The method according to claim 43, wherein the toner particles contain a magnetic material.

63. The method according to claim 43, wherein the toner particles contain a silicon-containing magnetic material.

64. A toner for developing electrostatic images, comprising:

toner particles said inorganic fine powder being different from said metal oxide particles, inorganic fine powder, resin fine particles, and metal oxide particles;

wherein

the inorganic fine powder has a charging polarity identical to that of the toner particles and a specific surface area of 70-300 m² /g,

the resin fine particles have a charging polarity identical to that of the toner particles, a specific surface area of 5.0-20.0 m² /g and a volume resistivity of 10⁷ -10¹⁴ ohm.cm, and

the metal oxide particles have a charging polarity opposite to that of the toner particles and a specific surface area of 0.5-10.0 m² /g.

65. 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 said inorganic fine powder being different from said metal oxide particles;

the inorganic fine powder has a charging polarity identical to that of the toner particles and a specific surface area of 70-300 m² /g,

the resin fine particles have a charging polarity identical to that of the toner particles, a specific surface area of 5.0-20.0 m² /g and a volume resistivity of 10⁷ 10¹⁴ ohm.cm, and

the metal oxide particles have a charging polarity opposite to that of the toner particles and a specific surface area of 0.5-10.0 m² /g.