Method for the preparation of electrostatographic toner of controlled shape by evaporative limited coalescence
First Claim
1. A method for the preparation of electrostatographic toner comprising the steps of:
- (a) mixing carnauba wax in a first solvent heated to a temperature sufficient to dissolve the wax and cooling the resultant solution, so resulting in the precipitation of the wax in the form of fine needle-like structures;
(b) mixing the wax needles with a polymer material, a pigment, a second solvent and optionally a charge control agent to form an organic phase;
(c) dispersing the organic phase in an aqueous phase comprising a promoter and a particulate stabilizer and homogenizing the resultant mixture; and
(d) evaporating the second solvent and washing and drying the resultant product.
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Abstract
A method is described for the preparation of electrostatographic toner particles which involves the use of carnauba wax for treating the surface of a pigment employed The method involves recrystallizing carnauba wax from its natural state by dissolution in ethyl acetate and cooling to precipitate needle like structures The structures so obtained are then added to a mixture comprising a pigment, a polymer material, a solvent and optionally a charge control agent which mixture serves as the organic phase in a limited coalescence process. The toner particles produced in accordance with this method are non spherical in nature and evidence excellent fluidity and anti-blocking properties.
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Citations
18 Claims
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1. A method for the preparation of electrostatographic toner comprising the steps of:
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(a) mixing carnauba wax in a first solvent heated to a temperature sufficient to dissolve the wax and cooling the resultant solution, so resulting in the precipitation of the wax in the form of fine needle-like structures; (b) mixing the wax needles with a polymer material, a pigment, a second solvent and optionally a charge control agent to form an organic phase; (c) dispersing the organic phase in an aqueous phase comprising a promoter and a particulate stabilizer and homogenizing the resultant mixture; and (d) evaporating the second solvent and washing and drying the resultant product. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 16, 18)
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5. The method of claim I wherein the particulate stabilizer is selected from the group consisting of highly cross-linked latex particles and SiO2.
- 10. In a method for preparing electrostatographic toner by dispersing an organic phase in an aqueous phase to yield a layer of particulate stabilizer on the surface of a polymer, the improvement which comprises adding carnauba wax in a solvent to a polymer material, a pigment and optionally a charge control agent to form an organic phase for dispersing in the aqueous phase.
Specification