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US5364720A
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Magnetic developer for developing electrostatic images
Assignee: Canon Inc
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Filing: 1993-10-14
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Granted: 1994-11-15
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Expires: 2013-10-14
Abstract
Abstract A magnetic developer for developing electrostatic images is constituted by magnetic toner particles, each containing a binder resin having a melt viscosity of at most 5.0×10 6 poise at 150° C. and a magnetic material. The magnetic material is blended with a proportion (C) [wt. %] of inorganic fine particles based on the magnetic material to carry 0.2-5 wt. % of the inorganic fine particles secured to the magnetic material surface. The magnetic material has a specific surface area (A) [m 2 /g] before securing of the inorganic fine particles and is provided with an increase in surface area (B) [m 2 /g] by the securing of the inorganic fine particles; wherein the parameters A, B and C satisfy the following formulae (1) and (2): 0.1≦B/A≦0.8 (1) B<30×C (2). As a result, the magnetic developer is provided with an improved low-temperature fixability without causing problems accompanying the use of a low-temperature softening binder resin, such as deterioration of anti-offset characteristic, storage characteristic, developing characteristic.
Inventors
- 👤 Akihiko Nakazawa
- 👤 Masayoshi Kato
- 👤 Manabu Ohno
- 👤 Nobuyuki Okubo
- 👤 Shunji Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:43
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/083; G03G9/0836; G03G9/0839; G03G9/087; G03G9/08784; G03G9/08797
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
129 words
A magnetic developer for developing electrostatic images, comprising: magnetic toner particles, each containing a binder resin having a melt viscosity of at most 5.0×10 6 poise at 150° C. and a magnetic material, wherein said magnetic material is blended with a proportion (C) [wt. %] of inorganic fine particles based on the magnetic material to carry 0.2-5 wt. % of the inorganic fine particles secured to the magnetic material surface, and said magnetic material has a specific surface area (A) [m 2 /g] before securing of the inorganic fine particles and is provided with an increase in surface area (B) [m 2 /g] by the securing of the inorganic fine particles; wherein the parameters A, B and C satisfy the following formulae (1) and (2): 0.1≦B/A≦0.8 (1) B<30×C (2).
Claim 2
Dependent Claim
129 words
A magnetic developer for developing electrostatic images, comprising: magnetic toner particles, each containing a binder resin having a melt viscosity of at most 5.0×10 6 poise at 150° C. and a magnetic material, wherein said magnetic material is blended with a proportion (C) [wt. %] of inorganic fine particles based on the magnetic material to carry 0.2-5 wt. % of the inorganic fine particles secured to the magnetic material surface, and said magnetic material has a specific surface area (A) [m 2 /g] before securing of the inorganic fine particles and is provided with an increase in surface area (B) [m 2 /g] by the securing of the inorganic fine particles; wherein the parameters A, B and C satisfy the following formulae (1) and (2): 0.1≦B/A≦0.8 (1) B<30×C (2).
Claim 3
Dependent Claim
23 words
The magnetic developer according to claim 1, wherein the inorganic fine particles secured to the magnetic material surface have been imparted with hydrophobicity.
Claim 4
Dependent Claim
23 words
The magnetic developer according to claim 1, wherein the inorganic fine particle have been secured to the magnetic material surface by mechanical treatment.
Claim 5
Dependent Claim
15 words
The magnetic developer according to claim 1, wherein the parameters A and B satisfy 0.3≦B/A≦0.6.
Claim 6
Dependent Claim
15 words
The magnetic developer according to claim 1, wherein the parameters B and C satisfy B<20×C.
Claim 7
Dependent Claim
15 words
The magnetic developer according to claim 1, wherein the parameters B and C satisfy B<15×C.
Claim 8
Dependent Claim
37 words
The magnetic developer according to claim 1, wherein the inorganic fine particles have a BET specific surface area (D) [m 2 /g] satisfying the following formula (3) in combination with the parameters B and C: 0.4≦B/(0.01×C×D)≦2.5 (3).
Claim 9
Dependent Claim
16 words
The magnetic developer according to claim 7, wherein the parameters B, C and D satisfy: 0.6≦B/(0.01×C×D)≦1.8.
Claim 10
Dependent Claim
21 words
The magnetic developer according to claim 1, wherein the magnetic material has a specific surface area of 4-15 m 2 /g.
Claim 11
Dependent Claim
21 words
The magnetic developer according to claim 1, wherein the magnetic material has a specific surface area of 5-12 m 2 /g.
Claim 12
Dependent Claim
23 words
The magnetic developer according to claim 1, wherein the inorganic fine particles have a BET specific surface area of 50-450 m 2 /g.
Claim 13
Dependent Claim
23 words
The magnetic developer according to claim 1, wherein the inorganic fine particles have a BET specific surface area of 80-400 m 2 /g.
Claim 14
Dependent Claim
28 words
The magnetic developer according to claim 1, wherein the magnetic material is contained in an amount of 30-150 wt. parts per 100 wt. parts of the binder resin.
Claim 15
Dependent Claim
28 words
The magnetic developer according to claim 1, wherein the magnetic material is contained in an amount of 40-120 wt. parts per 100 wt. parts of the binder resin.
Claim 16
Dependent Claim
40 words
The magnetic developer according to claim 1, wherein the inorganic fine particles comprise an inorganic substance selected from the group consisting of silica, titania, alumina, zirconium oxide, magnesium oxide, zinc oxide, cerium oxide, boron nitride, aluminum nitride, and carbon nitride.
Claim 17
Dependent Claim
14 words
The magnetic developer according to claim 1, wherein the inorganic fine particles comprise silica.
Claim 18
Dependent Claim
14 words
The magnetic developer according to claim 1, wherein the inorganic fine particles comprise alumina.
Claim 19
Dependent Claim
15 words
The magnetic developer according to claim 1, wherein the inorganic fine particles comprise titanium oxide.
Claim 20
Dependent Claim
19 words
The magnetic developer according to claim 1, wherein the inorganic fine particles have a hydrophobicity of at least 30%.
Claim 21
Dependent Claim
19 words
The magnetic developer according to claim 1, wherein the inorganic fine particles have a hydrophobicity of at least 50%.
Claim 22
Dependent Claim
35 words
The magnetic developer according to claim 1, wherein the magnetic toner has been blended with 0.1-3 wt. % of inorganic fine powder having a BET specific surface area of at least 50 m 2 /g.
Claim 23
Dependent Claim
35 words
The magnetic developer according to claim 1, wherein the magnetic toner has been blended with 0.1-3 wt. % of inorganic fine powder having a BET specific surface area of at least 100 m 2 /g.
Claim 24
Dependent Claim
26 words
The magnetic developer according to claim 1, wherein the inorganic fine particles are added in a proportion (C) of 0.1-3.5 wt. % of the magnetic material.
Claim 25
Dependent Claim
26 words
The magnetic developer according to claim 1, wherein the inorganic fine particles are added in a proportion (C) of 0.2-3 wt. % of the magnetic material.
Claim 26
Dependent Claim
20 words
The magnetic developer according to claim 1, wherein said magnetic toner particles have a weight-average particle size of 3-9 μm.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-11-14 | 1998-05-16 | 1998-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-14 | 2002-05-16 | 2002-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-14 | 2006-05-16 | 2006-11-15 | $7700.00 | Window Closed / Lapsed |