Stabilized carriers with .beta. phase poly(vinylidenefluoride)

• US 5,516,615 A
• Filed: 01/31/1995
• Issued: 05/14/1996
• Est. Priority Date: 01/31/1995
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Tyagi, Dinesh, Anderson, James H., DeMeyer, Dennis E.
• Primary Examiner(s): MARTIN, ROLAND E
• Application Number:
  US08/381,246
• Time in Patent Office: 469 Days
• Field of Search: 430/106.6, 430/108
• US Class Current: 430/111.33
• CPC Class Codes: G03G 9/1085 with non-ferrous metal oxide, e.g. MgO-Fe2O3
• CPC Class Codes: G03G 9/113 having coatings applied thereto
• CPC Class Codes: G03G 9/1131 Coating methods; Structure of coatings
• CPC Class Codes: G03G 9/1134 containing fluorine atoms

Abstract

A method for converting α-phase poly(vinylidene fluoride) to β-phase poly(vinylidene fluoride), for preparing electrostatographic carrier and, electrostatographic developer and carrier. In the method for preparing electrostatographic carrier, uncoated electrostatographic carrier particles are coated with α-phase poly(vinylidene fluoride) to provide α-phase poly(vinylidene fluoride) coated carrier particles. A measurable portion of the α-phase poly(vinylidene fluoride) is then converted to β-phase poly(vinylidene fluoride) by subjecting the α-phase poly(vinylidene fluoride) to a series of viscoelastic collisions having a total energy of from about 5×10⁴ to about 5×10⁵ Joules/kilogram of poly(vinylidene fluoride).

Claims

1. An electrostatographic carrier comprising:

carrier cores having a coating of poly(vinylidene fluoride), said polyvinylidene fluoride having a surface exposed to the ambient environment, said surface being at least 50 mole percent β

-phase poly(vinylidene fluoride).

2. The carrier of claim 1 wherein said poly(vinylidene fluoride) has a concentration relative to said carrier cores of from about 0.001 weight/weight percent to about 5 weight/weight percent.

3. The carrier of claim 1 wherein said carrier cores are metallic.

4. The carrier of claim 1 wherein said carrier cores are strontium ferrites.

5. Electrophotographic developer comprising the carrier of claim 1 and toner.

6. The developer of claim 5 wherein said toner further comprises styrenic/acrylic copolymer.

7. The developer of claim 5 wherein said toner further comprises a positive charge control agent.