Treated ferromagnetic carrier particles for development powders
AssigneePitney Bowes Inc.
InventorsGeorge Brana, Bheema Rao Vijayendran
Life of this patent
Estimating the term…
Abstract
Carrier particles of development powders are treated with a sodium salt of polystyrene sulfonic acid. As a result of the treatment, the triboelectric properties of the carrier particles are better controlled.
Claims7
A ferromagnetic carrier particle for use in electrophotographic development of latent images capable of inducing an electrostatic charge in a toner mixed therewith the surface of which has been treated with a sodium salt of polystyrene sulfonic acid having a minimum molecular weight of 50,000, said treated particle having a charge to mass ratio of 24 .times. 10.sup.-6 to 36 .times. 10.sup.-6 coul/gm.
In a method of treating ferromagnetic carrier particles for development powders, the combination comprising:
- A. adding a quantity of the sodium salts of polystyrene sulfonic acid to a solvent to produce a 10-80% solution of said sulfonic acid salt to solvent;
- B. adding a second acid to said solution to obtain a pH of 2.0 to 2.5;
- C. placing the carrier particles having a particle size of 50 to 400 microns into the solution in the proportion of up to 500 grams of particles per 100 cc of solution to form a mixture;
- D. rolling the mixture;
- E. decanting the excess solution from the mixture;
- F. washing the carrier particles;
- and
- G. drying the carrier particles.
Dependencies are inferred from the claim text.