Claims
- 1. A one component magnetic developer comprising:
- (i) a magnetic toner, said magnetic toner comprising:
- (a) a binder resin, said binder resin selected from the group consisting of a copolymer of styrene and acrylic acid ester, a copolymer of styrene and methacrylic acid ester and polyester resin, said binder resin being contained in an amount of 40-80 % by weight based on the total weight of the magnetic toner,
- (b) a low molecular weight polypropylene or low molecular weight polyethylene,
- (c) a metal complex dye or nigrosine, and
- (d) a magnetic powder having a number average particle size 0.2-0.7 microns, said magnetic powder consisting essentially of iron oxide having an excess Fe.sup.III content in said magnetic powder, said iron oxide containing 16-25% by weight FeO and about 75-84% by weight of Fe.sub.2 O.sub.3, based on the iron oxide, said magnetic powder being contained in an amount of 20-60% by weight based on the total weight of said magnetic toner, and
- (ii) a hydrophobic silica.
- 2. The magnetic toner of claim 1, wherein the specific surface area of the magnetic powder is 2-10 m.sup.2 /g.
- 3. The magnetic toner of claim 1, wherein the coercive force (Hc) is up to 300 oersteds.
- 4. The magnetic toner of claim 1, wherein the saturated magnetizing force (.sigma.s) is at least 60 emu/g.
- 5. The magnetic toner of claim 1, wherein the magnetic powder is prepared by neutralizing a ferrous sulfate solution and filtering and drying the resulting cubic crystal form of tri-iron tetraoxide.
- 6. The magnetic toner of claim 5, wherein the magnetic powder is prepared by oxidizing treatment of the tri-iron tetraoxide after said filtration and drying.
- 7. The magnetic toner of claim 1, wherein the magnetic powder is prepared by neutralizing a ferrous sulfate solution, and subjecting the resulting colloidal precipitate to a pressurized hydrothermal treatment at a pH of the mother liquor of 4-10 to convert the precipitate into a cubic crystal-like .alpha.-Fe.sub.2 O.sub.3, followed by a reducing treatment of the resulting .alpha.-Fe.sub.2 O.sub.3.
- 8. The magnetic toner of claim 1, wherein the magnetic powder contains from 18-24.5% by weight of FeO.
- 9. The magnetic toner of claim 1, wherein the magnetic powder containing 16-25% by weight of FeO is prepared by oxidizing a magnetite powder containing 26-34% by weight of FeO.
- 10. The magnetic toner of claim 1 wherein the binder resin is contained in an amount of 40-80% by weight, the waxy material is contained in an amount of 0.5-5% by weight and the magnetic powder is contained in an amount of 20-60% by weight, based on the total weight of the magnetic toner.
- 11. The magnetic toner of claim 10, wherein the magnetic powder has a coercive force (Hc) up to 300 oersteds.
- 12. The magnetic toner of claim 10, wherein the magnetic powder is prepared by oxidizing a magnetic powder containing 26-34% by weight of FeO.
- 13. The magnetic toner according to claim 1, wherein the magnetic powder comprises oxidized magnetite.
- 14. The magnetic toner of claim 13, wherein the specific surface area of the magnetite powder is 2-10 m.sup.2 /g.
- 15. The magnetic toner of claim 13, wherein the coercive force (Hc) is up to 300 oersteds.
- 16. The magnetic toner of claim 13, wherein the mangetite powder is prepared by neutralizing a ferrous sulfate solution to obtain cubic crystal triiron tetroxide and by filtering and drying the triiron tetraoxide.
- 17. The magnetic toner of claim 16, wherein the magnetite powder is prepared by oxidizing the filtered triiron tetraoxide.
- 18. The magnetic toner of claim 13, wherein the magnetite powder is prepared by neutralizing a ferrous sulfate solution to obtain a colloidal precipitate in a mother liquor, by subjecting the colloidal precipitate to a pressurized hydrothermal treatment at a mother liquor pH of about 4-10 to convert the precipitate into a cubic crystal-like .alpha.-Fe.sub.2 O.sub.3 and by then reducing the .alpha.-Fe.sub.2 O.sub.3.
- 19. The magnetic toner of claim 13, wherein the magnetite powder contains 18-24.5% by weight of FeO.
- 20. The magnetic toner of claim 13, wherein the magnetite powder containing 16-25% by weight of FeO is prepared by oxidizing a magnetite powder containing 26-34% by weight of FeO.
- 21. The magnetic toner of claim 20, wherein the binder is contained in an amount of 40-80% by weight, the waxy material is contained in an amount of 0.5-5% by weight and the magnetite powder is contained in an amount of 20-60% by weight, based on the total weight of the magnetic toner.
- 22. The magnetic toner of claim 21, wherein the magnetite powder has a coercive force (Hc) up to 300 oersteds.
- 23. The magnetic toner of claim 21, wherein the magnetite is prepared by oxidizing a magnetic powder containing 26-34% by weight of FeO.
- 24. A one component magnetic developer comprising:
- (A) a magnetic toner comprising:
- (a) a binder resin, said binder resin selected from the group consisting of a copolymer of styrene and acrylic acid ester, a copolymer of styrene and methacrylic acid ester and a polyester resin, said binder resin being contained in an amount of 40-80% by weight based on the total weight of the magnetic toner,
- (b) a low molecular weight polypropylene or low molecular weight polyethylene,
- (c) a metal complex dye or nigrosine, and
- (d) an oxidized magnetic powder uniformly dispersed in the binder resin, said oxidized magnetic powder consisting essentially of iron oxide having
- (i) an excess Fe.sup.III content in said magnetic powder;
- (ii) a weight ratio of Fe.sub.2 O.sub.3 to FeO from 3:1 to 5.25:1;
- (iii) a number average particle size of 0.2-0.7 microns, and
- (iv) a coercive force (Hc) of up to 300 oersteds, said magnetic powder being contained in an amount of 20-60% by weight based on the total weight of the magnetic toner; and
- (B) a hydrophobic silica.
- 25. The magnetic toner of claim 24 wherein the binder resin is present in amounts from 40 to 80% by weight, the waxy material is present in amounts from 0.5 to 5% by weight and the magnetic powder is present in amounts from 20% to 60% by weight, based on the total weight of the magnetic toner.
- 26. The magnetic toner of claim 24 which includes a free-flow improver.
- 27. The magnetic toner of claim 26 wherein the free flow improver is a hydrophobic silica.
- 28. In the process of forming a toner image, comprising the step of: utilizing a photosensitive material, forming an electric latent image on the photosensitive material, developing the latent image with a developer in a field of A.C. bias and D.C. bias to obtain a toner image, transferring the toner image to an image receiving layer and fixing the transferred toner image, the improvement comprising employing as the developer a one component magnetic developer comprising:
- (i) a magnetic toner comprising:
- (a) a binder resin, said binder resin selected from the group consisting of a copolymer of styrene and acrylic acid ester, a copolymer of styrene and methacrylic acid ester and a polyester resin, said binder resin being contained in an amount of 40-80% weight based on the total weight of the magnetic toner,
- (b) a low molecular weight polypropylene or low molecular weight polyethylene;
- (c) a metal complex dye or nigrosine, and
- (d) a magnetic powder having a number average particle size of 0.2-0.7 microns, said magnetic powder consisting essentially of iron oxide having an excess Fe.sup.III content in said magnetic powder, said iron oxide containing 16-25% by weight of FeO and about 75-84% by weight of Fe.sub.2 O.sub.3, based on the iron oxide, said magnetic powder being contained in an amount of 20-60% by weight based on the total weight of the magnetic toner; and
- (ii) a hydrophobic silica.
- 29. The process according to claim 28, wherein the magnetic toner is supported on a sleeve and is carried in the form of a thin layer while being triboelectrically charged.
- 30. The process according to claim 29, wherein the thin layer of the magnetic toner on the sleeve is not brought into contact with the photosensitive material.
Priority Claims (1)
Number |
Date |
Country |
Kind |
57-54382 |
Apr 1982 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 217,121 filed July 5, 1988, which was a continuation of application Ser. No. 902,135 filed Sept. 2, 1986, which was a continuation of Ser. No. 696,895 filed Jan. 31, 1985, which was a continuation of Ser. No. 479,315 filed Mar. 28, 1983, each now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (3)
Number |
Date |
Country |
1165405 |
Oct 1969 |
GBX |
1165406 |
Oct 1969 |
GBX |
2040488 |
Aug 1980 |
GBX |
Continuations (4)
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Number |
Date |
Country |
Parent |
217121 |
Jul 1988 |
|
Parent |
902135 |
Sep 1986 |
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Parent |
696895 |
Jan 1985 |
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Parent |
479315 |
Mar 1983 |
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