US 6,319,647 B1 · Toner and developer for magnetic brush development system

Abstract

A toner of toner particles containing at least one binder, at least one colorant, and preferably one or more external additives is advantageously formed into a developer and used in a magnetic brush development system to achieve consistent, high quality copy images. The toner particles, following triboelectric contact with carrier particles, exhibit a charge per particle diameter (Q/D) of from 0.6 to 0.9 fC/μm and a triboelectric charge of from 20 to 25 μC/g. The toner particles preferably have an average particle diameter of from 7.8 to 8.3 microns. The toner is combined with carrier particles to achieve a developer, the carrier particles preferably having an average diameter of from 45 to 55 microns and including a core of ferrite substantially free of copper and zinc coated with a coating comprising a polyvinylidenefluoride polymer or copolymer and a polymethyl methacrylate polymer or copolymer.

Claims18

Dependent claims

A toner comprising toner particles comprised of at least one binder, at least one colorant, and optionally one or more additives,

wherein following triboelectric contact with carrier particles comprising a core of ferrite coated with 0.1 to 3.0% by weight of the carrier particles of a coating comprising a polyvinylidenefluoride polymer or copolymer and a polymethyl methacrylate polymer or copolymer, and in which from 3 parts to 5 parts by weight of the toner is contacted with from 90 parts to 110 parts by weight of the carrier particles, the toner has a charge per particle diameter (Q/D) of from 0.6 to 0.9 fC/μm and a triboelectric charge of from 20 to 25 μC/g,
wherein the toner melt viscosity at 100° C. ranges from 35,000 to 70,000 poise, and
wherein the toner particles have a volume average particle diameter of from 7.8 to 8.3 microns.

A toner comprising toner particles comprised of

at least one binder resin comprising a propoxylated bisphenol A fumarate resin,
at least one colorant comprising pigment having a color selected from the group consisting of cyan, yellow, magenta and black, wherein if the pigment color is cyan, magenta or black, the binder resin has a gel content of from 10 to 15 percent by weight of the binder resin and if the pigment color is yellow, the binder resin contains no gel, and
external additives comprising untreated titania in an amount of 0.5 to 5.0 percent by weight of a total weight of the toner, hexamethyldisilazane treated silica in an amount of 0.1 to 3.0 percent by weight of the total weight of the toner, and zinc stearate in an amount of 0.1 to 2.0 percent by weight of the total weight of the toner,
and wherein following triboelectric contact with carrier particles comprising a core of ferrite coated with 0.1 to 3.0% by weight of the carrier particles of a coating comprising a polyvinylidenefluoride polymer or copolymer and a polymethyl methacrylate polymer or copolymer, and in which from 3 parts to 5 parts by weight of the toner is contacted with from 90 parts to 110 parts by weight of the carrier particles, the toner has a charge per particle diameter (Q/D) of from 0.6 to 0.9 fC/g μm and a triboelectric charge of from 20 to 25 μC/g.

1 more element

Dependencies are inferred from the claim text.

Toner and developer for magnetic brush development system

Life of this patent

Toner and developer for magnetic brush development system

Life of this patent

Abstract

Claims18