Electrostatographic developer mixtures comprising ferrite carrier beads

Claim 2

AN ELECTROSTATOGRAPHIC DEVELOPER MIXTURE COMPRISING FINELY-DIVIDED TONER PARTICLES ELECTROSTATICALLY CLINGING TO THE SURFACES OF CARRIER BEADS HAVING A PARTICLE SIZE FROM ABOUT 30 TO ABOUT 1,000 MICRONS, EACH OF SAID CARRIER BEADS COMPRISING NICKEL-ZINC FERRITE BEADS COMPRISING ABOUT 0.1 TO ABOUT 0.9 MOLES OF NICKEL, ABOUT 0.1 TO ABOUT 0.9 MOLES OF ZINC, AND ABOUT 1.4 TO ABOUT 4.0 MOLES OF IRON, SAID CARRIER BEADS BEING FURTHER CHARACTERIZED AS BEING SUBSTANTIALLY DENSE AND UNIFORM IN SIZE AND SHAPE WITH MAXIMUM ROUNDNESS AND SPHERICITY AND HAVING SUBSTANTIALLY UNIFORM ELECTROSTATOGRAPHIC PROPERTIES SUCH AS TRIBOELECTRICITY, MAGNETIC PERMEABILITY, AND ELECTRICAL CONDUCTIVITY.

Claim 3

An electrostatographic developer mixture according to claim 1 wherein said developer mixture comprises about 1 part by weight of said toner particles and between about 10 and about 200 parts by weight of said nickel-zinc ferrite beads.

Claim 4

An electrostatographic developer mixture according to claim 1 wherein said toner particles have an average particle diameter between about 1 and about 30 microns.

Claim 5

An electrostatographic developer mixture according to claim 1 wherein said nickel-zinc ferrite beads have a triboelectric charging capacity of from about 8 to about 40 microcoulombs per gram of said toner particles.

Claim 6

AN ELECTROSTATOGRAPHIC DEVELOPER MIXTURE COMPRISING FINELY-DIVIDED TONER PARTICLES ELECTROSTATICALLY CLINGING TO THE SURFACES OF CARRIER BEADS HAVING A PARTICLE SIZE FROM ABOUT 30 TO ABOUT 1,000 MICRONS, EACH OF SAID CARRIER BEADS COMPRISING MANGANESE-ZINC FERRITE BEADS COMPRISING ABOUT 0.1 TO ABOUT 0.9 MOLES OF MANGANESE, ABOUT 0.1 TO ABOUT 0.9 MOLES OF ZINC, AND ABOUT 1.4 TO ABOUT 4.0 MOLES OF IRONN, SAID CARRIER BEADS BEING FURTHER CHARACTERIZED AS BEING SUBSTANTIALLY DENSE AND UNIFORM IN SIZE AND SHAPE WITH MAXIMUM ROUNDNESS AND SPHERICITY AND HAVING SUBSTANTIALLY UNIFORM ELECTROSTATOGRAPHIC PROPERTIES SUCH AS TRIBOELECTRICITY, MAGNETIC PERMEABILITY, AND ELECTRICAL CONDUCTIVITY.

Claim 7

AN ELECTROSTATOGRAPHIC DEVELOPER MIXTURE COMPRISING FINELY-DIVIDED TONER PARTICLES ELECTROSTATICALLY CLINGING TO THE SURFACES OF CARRIER BEADS HAVING A PARTICLE SIZE FROM ABOUT 30 TO ABOUT 1,000 MICRONS, EACH OF SAID CARRIER BEADS COMPRISING MANGANESE-ZINC FERRITE BEADS COMPRISING ABOUT 0.1 TO ABOUT 0.9 MOLES OF MANGANESE, ABOUT 0.1 TO ABOUT 0.9 MOLES OF ZINC, AND ABOUT 1.4 TO ABOUT 4.0 MOLES OF IRONN, SAID CARRIER BEADS BEING FURTHER CHARACTERIZED AS BEING SUBSTANTIALLY DENSE AND UNIFORM IN SIZE AND SHAPE WITH MAXIMUM ROUNDNESS AND SPHERICITY AND HAVING SUBSTANTIALLY UNIFORM ELECTROSTATOGRAPHIC PROPERTIES SUCH AS TRIBOELECTRICITY, MAGNETIC PERMEABILITY, AND ELECTRICAL CONDUCTIVITY.

Claim 8

An electrostatographic developer mixture according to claim 5 wherein said developer mixture comprises about 1 part by weight of said toner particles and between about 10 and about 200 parts by weight of said manganese-zinc ferrite beads.

Claim 9

An electrostatographic developer mixture according to claim 5 wherein said toner particles have an average particle diameter between about 1 and about 30 microns.

Claim 10

An electrostatographic developer mixture according to claim 5 wherein said manganese-zinc ferrite beads have a triboelectric charging capacity of from about 8 to about 40 microcoulombs per gram of said toner particles.

Claim 11

An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surfaces of carrier beads having a particle size from about 30 to about 1,000 microns, each of said carrier beads comprising nickel-zinc ferrite beads comprising about 0.1 to about 0.9 moles of nickel, about 0.1 to about 0.9 moles of zinc, and about 1.4 to about 4.0 moles of iron, said carrier beads having been produced by preparing a slurry of ferrite forming metal oxides in a liquid, spray drying said slurry of said ferrite forming metal oxides to form substantially spherical metal oxide beads and sintering said substantially spherical metal oxide beads to form ferrite beads while maintaining the spherical shape and particulate naTure of the beads, said carrier beads being further characterized as being substantially dense and uniform in size and shape with maximum roundness and sphericity and having substantially uniform electrostatographic properties such as triboelectricity, magnetic permeability, and electrical conductivity.

Claim 12

An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surfaces of carrier beads having a particle size from about 30 to about 1,000 microns, each of said carrier beads comprising nickel-zinc ferrite beads comprising about 0.1 to about 0.9 moles of nickel, about 0.1 to about 0.9 moles of zinc, and about 1.4 to about 4.0 moles of iron, said carrier beads having been produced by preparing a slurry of ferrite forming metal oxides in a liquid, spray drying said slurry of said ferrite forming metal oxides to form substantially spherical metal oxide beads and sintering said substantially spherical metal oxide beads to form ferrite beads while maintaining the spherical shape and particulate naTure of the beads, said carrier beads being further characterized as being substantially dense and uniform in size and shape with maximum roundness and sphericity and having substantially uniform electrostatographic properties such as triboelectricity, magnetic permeability, and electrical conductivity.

Claim 13

An electrostatographic developer mixture according to claim 9 wherein said metal oxide beads have been sintered at a temperature of between about 900*C and about 1,600*C for between about 5 minutes to about 5 hours.

Claim 14

An electrostatographic developer mixture according to claim 9 wherein said developer mixture comprises about 1 part of said toner particles and between about 10 and about 200 parts by weight of said carrier beads.

Claim 15

An electrostatographic developer mixture according to claim 9 wherein said nickel-zinc ferrite comprises a nickel to zinc molar ratio of at least about 0.3.

Claim 16

An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of carrier beads having a particle size from about 30 to about 1, 000 microns, each of said carrier beads comprising manganese-zinc ferrite beads comprising about 0.1 to about 0.9 moles of manganese, about 0.1 to about 0.9 moles of zinc, and about 1.4 to about 4.0 moles of iron, said carrier beads having been produced by preparing a slurry of ferrite forming metal oxides in a liquid, spray drying said slurry of said ferrite forming metal oxides to form substantially spherical metal oxide beads and sintering said substantially spherical metal oxide beads to form ferrite beads while maintaining the spherical shape and particulate nature of the beads, said carrier beads being further characterized as being substantially dense and uniform in size and shape with maximum roundness and sphericity and having substantially uniform electrostatographic properties such as triboelectricity, magnetic permeability, and electrical conductivity.

Claim 17

An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of carrier beads having a particle size from about 30 to about 1, 000 microns, each of said carrier beads comprising manganese-zinc ferrite beads comprising about 0.1 to about 0.9 moles of manganese, about 0.1 to about 0.9 moles of zinc, and about 1.4 to about 4.0 moles of iron, said carrier beads having been produced by preparing a slurry of ferrite forming metal oxides in a liquid, spray drying said slurry of said ferrite forming metal oxides to form substantially spherical metal oxide beads and sintering said substantially spherical metal oxide beads to form ferrite beads while maintaining the spherical shape and particulate nature of the beads, said carrier beads being further characterized as being substantially dense and uniform in size and shape with maximum roundness and sphericity and having substantially uniform electrostatographic properties such as triboelectricity, magnetic permeability, and electrical conductivity.