Dry toner, and its production process
AssigneeSeiko Epson Corporation
InventorHiroshi Katagiri
Life of this patent
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Abstract
The object of the present invention is to achieve a dry toner that is of improved low-temperature fixability, pulverizability, offset resistance, durability and storability as well as improved transparency and light resistance and so provides a useful color toner, and provide a dry toner production process of improved continuous productivity. The dry toner of the invention is characterized by comprising as a binder resin a polymer that is obtained by bulk polymerization of a compound having at least two isocyanate groups and a compound having at least two functional groups, each containing active hydrogen, contains an urethane bond or urea bond in its main chain and has a number-average molecular weight (Mn) of 1,500 to 20,000 as measured on a polystyrene basis.
Claims11
A dry toner, comprising as a binder resin a polymer that is obtained by bulk polymerization of a compound having at least two isocyanate groups and a compound having at least two functional groups, each containing active hydrogen, contains an urethane bond or urea bond in its main chain and has a number-average molecular weight, Mn, of 1,500 to 20,000 as measured on a polystyrene basis.
A dry toner production process, wherein a polymer containing an urethane bond or urea bond in its main chain and having a number-average molecular weight Mn of 1,500 to 20,000 as measured on a polystyrene basis is obtained by bulk polymerization of a polyisocyanate having at least two isocyanate groups and a compound having at least two function groups, each having active hydrogen, in the absence of any solvent, and said polymer is then kneaded with a coloring agent, followed by grinding.
A dry toner production process, wherein:
- a compound having at least two isocyanate groups and a compound having at least two functional groups, each having active hydrogen, are mixed together in the absence of any solvent,
- a mixture is continuously fed into a double-shaft extrusion reactor comprising a barrel, a barrel inlet, a side feeder provided on an intermediate portion of said barrel and a barrel outlet from said barrel inlet for bulk polymerization, thereby obtaining a polymer containing an urethane bond or urea bond in its main chain and having a number-average molecular weight Mn of 1,500 to 20,000 as measured on a polystyrene basis, and
- a pigment-containing additive is continuously fed from said side feeder, a kneaded mixture of said pigment-containing additive and said bulk polymerization product is continuously discharged from said barrel outlet, and the thus discharged kneaded mixture is ground.
Dependencies are inferred from the claim text.