US4265992A
Expired / Lapsed
US
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Coated magnetic developer particles for electrophotography containing vinyl and olefin resins
Assignee: Kyocera Mita Industrial Co Ltd
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Filing: 1978-07-31
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Granted: 1981-05-05
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Expires: 1998-07-31
Abstract
Abstract In a one-component type developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles and flowability- and electric resistance-controlling fine particles, when an aromatic vinyl resin and/or an acrylic resin is used as a binder resin for the magneto-sensitive particles in combination with a low molecular weight olefin resin, the magneto-sensitive particles are much improved in the property of holding the flowability- and electric resistance-controlling fine particles on the surfaces thereof. Accordingly, these fine particles cannot be substantially separated from the magneto-sensitive particles under agitation conditions, development conditions and fixing conditions. As a result, contamination of the interior of a copying machine, especially an optical system, can be completely prevented, and also contamination of the background can be completely prevented. Further, the resulting fixed images have a very high resistance to friction and abrasion, and troubles such as blurring and flow of the image are not caused at all.
Inventors
- 👤 Toshihiro Kouchi
- 👤 Hiroshi Takayama
- 👤 Tatsuo Aizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:57
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/083; G03G9/0839; G03G9/0831; G03G9/0833; G03G9/087; G03G9/08702; G03G9/08704; G03G9/08706; G03G9/08742; G03G9/08746; G03G9/08748; G03G9/08775
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
207 words
A developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50μ and flowability and electric resistance-controlling fine particles having particle size of up to 1 micron in an amount of 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, wherein said fixing magneto-sensitive particles are obtained by kneading a composition comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resins and (D) a low-molecular-weight olefin resin at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), cooling the kneaded composition and pulverizing the cooled composition and said flowability-and electric resistance-controlling fine particles are adhering to and held on the surfaces of said fixing magneto-sensitive particles substantially inseparably therefrom wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 2
Dependent Claim
207 words
A developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50μ and flowability and electric resistance-controlling fine particles having particle size of up to 1 micron in an amount of 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, wherein said fixing magneto-sensitive particles are obtained by kneading a composition comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resins and (D) a low-molecular-weight olefin resin at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), cooling the kneaded composition and pulverizing the cooled composition and said flowability-and electric resistance-controlling fine particles are adhering to and held on the surfaces of said fixing magneto-sensitive particles substantially inseparably therefrom wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 3
Dependent Claim
35 words
A developer as set forth in claim 1 which has an electric resistance of 10 6 to 10 12 Ω-cm, an angle of repose of 30° to 60° and a cohesion ratio lower than 5%.
Claim 4
Dependent Claim
33 words
A developer as set forth in claim 1 wherein said olefin resin has a weight average molecular weight of from 1,000 to about 10,000 and a softening point of 80° to 160° C.
Claim 5
Dependent Claim
21 words
A developer as set forth in claim 1 wherein said flowability and electric resistance-controlling fine particles are composed of carbon black.
Claim 6
Dependent Claim
220 words
A developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50μ and fine carbon black particles having a particle size of up to 1μ in an amount of 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, wherein said fixing magneto-sensitive particles are obtained by kneading a composition comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resins and (D) an olefin resin having a weight average molecular weight of 1,000 to 10,000 and a softening point of 80° to 160° C. at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), cooling the kneaded composition and pulverizing the cooled composition and said fine particles are adhering to and held on the surfaces of said fixing magneto-sensitive particles substantially inseparably therefrom wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 7
Dependent Claim
220 words
A developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50μ and fine carbon black particles having a particle size of up to 1μ in an amount of 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, wherein said fixing magneto-sensitive particles are obtained by kneading a composition comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resins and (D) an olefin resin having a weight average molecular weight of 1,000 to 10,000 and a softening point of 80° to 160° C. at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), cooling the kneaded composition and pulverizing the cooled composition and said fine particles are adhering to and held on the surfaces of said fixing magneto-sensitive particles substantially inseparably therefrom wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 8
Dependent Claim
199 words
A carrierless developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50 microns and flowability-and electric resistance-controlling fine particles having a particle size of up to 1 micron adhered to and held on the surface of said fixing magneto-sensitive particles substantially inseparably therefrom, but without being embedded in said fixing magneto-sensitive particles, the amount of said fine particles being from about 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, said fixing magneto-sensitive particles comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resin and (D) a low-molecular-weight olefin resin at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 9
Dependent Claim
199 words
A carrierless developer for electrophotography consisting essentially of a dry blend of fixing magneto-sensitive particles having a particle size of 5 to 50 microns and flowability-and electric resistance-controlling fine particles having a particle size of up to 1 micron adhered to and held on the surface of said fixing magneto-sensitive particles substantially inseparably therefrom, but without being embedded in said fixing magneto-sensitive particles, the amount of said fine particles being from about 0.001 to 2 parts by weight per 100 parts by weight of said fixing magneto-sensitive particles, said fixing magneto-sensitive particles comprising (A) Fe 3 O 4 or γ-Fe 2 O 3 , (B) carbon black, (C) a binder resin composed mainly of at least one resin selected from the group consisting of aromatic vinyl resins and acrylic resin and (D) a low-molecular-weight olefin resin at an (A):(B):(C):(D) mixing weight ratio of (20-80):(0.5-20):(18-40):(0.5-30), wherein said binder resin (C) is present in the fixing magneto-sensitive particles in the form of a continuous phase and said low-molecular-weight olefin resin (D) is present in the fixing magneto-sensitive particles in the form of a dispersed phase together with Fe 3 O 4 or γ-Fe 2 O 3 (A) and carbon black (B).
Claim 10
Dependent Claim
35 words
A developer as set forth in claim 6 which has an electric resistance of 10 6 to 10 12 Ω-cm, an angle of repose of 30° to 60° and a cohesion ratio lower than 5%.
Claim 11
Dependent Claim
33 words
A developer as set forth in claim 7 wherein said olefin resin has a weight average molecular weight of about 1,000 to about 10,000 and a softening point of 80° to 160° C.
Claim 12
Dependent Claim
21 words
A developer as set forth in claim 8 wherein said flowability and electric resistance-controlling fine particles are composed of carbon black.
Claim 13
Dependent Claim
16 words
A developer as set forth in claim 9 wherein the (A):(B):(C):(D) mixing weight ratio is (40-75):(1-10):(20-35):(1-15).
Claim 14
Dependent Claim
74 words
A developer as set forth in claim 10 wherein said aromatic vinyl resin is a homopolymer or copolymer of a monomer represented by the formula: ##STR4## wherein R 1 stands for a hydrogen atom or a lower alkyl group, R 2 stands for a lower alkyl group, a lower alkoxy group, a nitro group, an amino group, a halogen atom or other substituent, and n is 0 or an integer of 1 or 2.
Claim 15
Dependent Claim
24 words
A developer as set forth in claim 10 wherein said binder resin (C) has a molecular weight in the range of 500 to 75,000.
Claim 16
Dependent Claim
24 words
A developer as set forth in claim 12 wherein said binder resin (C) has a molecular weight in the range of 1,000 to 30,000.
Claim 17
Dependent Claim
31 words
A developer as set forth in claim 13 wherein the amount of the fine carbon black particles range from about 0.1 to 1.0 percent by weight, based on the magneto-sensitive particles.
References Cited (Backward Citations)
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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) | 1984-05-04 | 1984-11-03 | 1985-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-05-04 | 1988-11-03 | 1989-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-05-04 | 1992-11-03 | 1993-05-05 | $7700.00 | Window Closed / Lapsed |