Electrographic developing composition and process

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely-divided crosslinked toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.1 to about 100 microns and comprising at least about 25 percent by weight of a fusible binder polymer, said polymer being covalently crosslinked to an extent sufficient (a) to provide a useful fusing range for said toner particles of at least about 90.degree. C. and (b) to extend the useful fusing range of the toner particles by at least about 20.degree. C. relative to comparable uncrosslinked toner particles comprising the same binder polymer except in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided toner particles electrostatically attractable thereto, said toner particles having an average particle size of from about 0.1 to about 100 microns and comprising at least about 50 percent by weight of a fusible binder polymer, the improvement wherein said binder is a covalently crossliked polymeric reaction product of (1) one or more crosslinking organic compounds possessing two or more polymerizable ethylenically unsaturated groups and (2) one or more organic compounds possessing one polymerizable ethylenically unsaturated group, said binder being crosslinked to an extent sufficient (a) to provide a useful fusing range for said toner particles of at least about 90.degree. C. and (b) to extend the useful fusing range of said toner particles by at least about 20.degree. C. relative to comparable uncrosslinked toner particles comprising the same binder polymer except in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.1 to about 100 microns and comprising at least about 50 percent by weight of a fusible polymeric binder, the improvement wherein said binder is a covalently crosslinked polymeric reaction product of (1) one or more crosslinking organic compounds possessing a polymerizable functionality greater than two and (2) a blend comprising a dicarboxylic acid and a polyhydric alcohol capable of reacting with one another to form a polymer having individual units thereof linked by ester groups, said binder being crosslinked to an extent sufficient (a) to provide a fusing range for said toner particles of at least about 90.degree. C. and (b) to extend the useful fusing range of said toner particles by at least about 20.degree. C. relative to comparable uncrosslinked toner particles comprising the same binder polymer in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided tone particles electrostatically attractable thereto, said toner particles having an average particle size of from about 0.1 to about 100 microns and comprising at least about 50 percent by weight of a fusible polymeric binder, the improvement wherein said binder is a covalently crosslinked polymeric reaction product of a curing agent and a polymer having crosslinking sites along its molecular structure capable of reacting with said curing agent, said binder being crosslinked (a) to provide a useful fusing range for said toner particles of at least about 90.degree. C. and (b) to an extent sufficient to extend the useful fusing range of said toner particles by at least about 20.degree. C. relative to comparable uncrosslinked toner particles comprising the same binder polymer in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided crosslinked toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.1 to about 100 microns and comprising a dye and/or pigment as colorant and a fusible styrene-containing binder polymer, said binder polymer being covalently crosslinked (a) to provide a useful fusing range for said toner particles of at least about 90.degree. C. and (b) to an extent sufficient to extend the useful fusing range of the toner particles by at least about 10.degree. C. relative to comparable uncrosslinked toner particles comprising said styrene-containing polymer in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided magnetically attractable carrier particles and from about 1 to about 15 percent by weight of finely divided crosslinked toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.1 to about 100 microns, and comprising at least about 75 percent by weight of a fusible binder polymer, said polymer having a softening temperature within the range of about 40.degree. C. to 200.degree. C. and being covalently crosslinked to an extent sufficient (a) to provide a useful fusing range for said toner particles of at least about 100.degree. C. and (b) to extend the useful fusing range of the toner particles by at least about 40.degree. C. relative to comparable uncrosslinked toner particles comprising said binder polymer in uncrosslinked form.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided crosslinked toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.01 to about 100 microns and comprising at least about 25 weight percent of a covalently crosslinked binder polymer, said polymer a polymeric reaction product of a mixture comprising (1) from about 0.01 to about 5 weight percent of one or more crosslinking organic compounds possessing two or more polymerizable ethylenically unsaturated groups and (2) one or more organic compounds possessing one polymerizable ethylenically unsaturated group.

An electrographic developing composition comprising a mixture of from about 85 to about 99 percent by weight of finely divided carrier particles and from about 1 to about 15 percent by weight of finely divided crosslinked toner particles electrostatically attractable thereto, said toner particles having an average particle size within the range of from about 0.1 to about 100 microns and comprising a pigment as colorant and at least about 50 percent by weight of a fusible covalently crosslinked styrene-containing polymer, said polymer a polymeric reaction product of a mixture comprising (1) from about 0.01 to about 5 weight percent of one or more crosslinking compounds possessing two or more polymerizable ethylenically unsaturated groups and (2) a monomeric blend having one polymerizable ethylenically unsaturated group and comprising from about 40 to 100 percent by weight of styrene or styrene homolog, said polymer having a softening temperature within the range of 40.degree. C. to 200.degree. C.

The developer composition as defined in claim [14] 13 wherein said polymer has a softening temperature within the range of from about 40.degree. C. to about 65.degree. C. and wherein said monomeric blend comprises from about 40 to about 90 percent by weight of styrene or styrene homolog and from about 10 to about 60 percent by weight of an alkyl acrylate or methacrylate having from about 1 to about 20 carbon atoms in the alkyl moiety.

In an electrographic imaging process wherein an electrostatic charge pattern is contacted with dry finely divided toner particles having an average particle size within the range of about 0.01 to about 100 microns comprising a fusible binder polymer to develop said charge pattern and, subsequently, the developed toner particle image corresponding to said charge pattern is fixed to a suitable receiving support by fusing said particles to said support, the improvement wherein (a) the molecular chains of said polymer are crosslinked, and remain crosslinked during fusing, to an extent sufficient to extend the useful fusing range of said toner particles by at least about 10.degree. C. relative to comparable uncrosslinked toner particles comprising said binder polymer in uncrosslinked form and (b) said polymer has a crosslink bond energy in excess of about 8 kcal/mole.

An electrographic imaging process according to claim [16] 15 wherein said molecular chains are covalently crosslinked.

An electrographic imaging process according to claim [16] 15 wherein molecular chains are ionically crosslinked.

A method for developing a latent electrostatic image bearing member comprising forming a latent electrostatic image on said member and applying a developer thereto, said developer including at least a toner where said toner is affected by said latent image to effect development thereof, said toner comprising a pulverized, colored, crosslinked, vinylic polymer resin obtained by (a) polymerizing the monomer thereof in the presence of a crosslinking agent of at least 0.01 percent by weight of the monomer, said crosslinking agent being a compound which forms a crosslinked polymer having a crosslink bond energy in excess of about 8 kcal/mole, (b) mixing at least one coloring material with the thus obtained resin and (c) pulverizing the obtained mixture.

A method for developing a latent electrostatic image bearing member comprising forming a latent electrostatic image on said member and applying a developer thereto, said developer including at least a toner where said toner is affected by said latent image to effect development thereof, said toner comprising a pulverized, colored, crosslinked, vinylic polymer resin obtained by (a) polymerizing the monomer thereof in the presence of a crosslinking agent of at least 0.01 percent by weight of the monomer, said crosslinking agent being selected from the group consisting of aromatic divinyl compounds, diethylenecarboxylate esters, and mixtures thereof, (b) mixing at least one coloring material with the thus obtained resin and (c) pulverizing the obtained mixture.