Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2000-09-07
2001-02-20
Martin, Roland (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
Reexamination Certificate
active
06190820
ABSTRACT:
COPENDING APPLICATIONS
Illustrated in U.S. Ser. No. (not yet assigned—D/99677), “Surfactant free Toner Aggregation Process”, filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of toner comprising: a process for the preparation of toner comprising: (i) generating by emulsion polymerization in the presence of an initiator a first resin latex emulsion; (ii) generating by polycondensation reaction a second resin latex in the presence of a catalyst; (iib) dispersing the resin of (ii) in warm water which is in the range of 50 95 degrees Centigrade and preferably in the range of 60 to 80 degrees Centigrade to provide a resin dispersion (iii) mixing (iib) with a colorant thereby providing a colorant dispersion; (iiib) mixing the resin latex emulsion of (I) with the resin/colorant mixture of (iii) to provide a blend of a resin and colorant; (iv) adding an aqueous inorganic cationic coagulant solution of a polymeric metal salt and optionally an organic cationic coagulant to the resin/colorant blend of (iiib); (v) heating at a temperature of from about 5 to about 10 degrees Centigrade below the resin Tg of (I), to thereby form aggregates particles and which particles are at a pH of form about 2 to about 3.5; (vi) adjusting the pH of (v) to about 6.5 to about 9 by the addition of a base; (vii) heating the aggregate particles of (v) at temperatures of from about 5 to about 50 degrees Centigrade above the Tg of the resin of (I), followed by a reduction of the pH to from about 2.5 to about 5 and preferably in the range of from about 3 to about 4.5 by the addition of an acid resulting in coalesced toner; (viii) optionally isolating the toner.
The appropriate components, reactants, process parameters, and the like of the above copending application may be selected for the present invention in embodiments thereof.
BACKGROUND OF THE INVENTION
The present invention relates to toner processes, and more specifically, to the preparation of a surfactant free latex wherein the resin particles contained therein are aggregated and coalesced with a colorant to provide toner compositions. More specifically, the present invention relates to a surfactant free toner process comprising (i) the preparation of an latex emulsion, containing submicron resin particles suspended in an aqueous phase, which phase is surfactant free, (ii) preparing a second resin which resin is readily dispersible in water to provide a dispersion of submicron particles in the diameter size range of, for example, about 50 to about 300 nanometers, and wherein the dispersion can be selected as a dispersant for the toner colorant particles thereby providing a stable colorant dispersion, followed by aggregation and coalescence with the latex emulsion of (i) to provide a toner composition. The resin (ii) utilized to stabilize the colorant, such as pigment particles is, for example, a styrene-butylacrylate-acrylic acid-4 styrene sulfonic acid, the sodium salt (sodium styrene sulfonate) or the like, and which resin is capable of self dispersing in warm water, for example from about 35° C. to about 85 degrees centigrade to provide a submicron particle size resin dispersion. Also, more specifically, the processes of the present invention can select dual coagulants such as an inorganic cationic metal salt and an organic cationic coagulant to, for example, facilitate aggregation of resin and colorant, such as pigment particles, both which can, for example, be in the size range of about 80 to about 4,000 nanometers and optionally a release agent such as a wax which can also be in the submicron diameter range and a charge control agent can be selected. With further respect to the processes of the present invention, there can be selected a staged increasing of the temperature during the coalescence wherein two or more temperature regions are selected to achieve the final coalescence followed by a staged changing of the pH of the aggregate mixture wherein the pH is lowered to, for example, provide toner process which are surfactant free.
PRIOR ART
Emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in a number of Xerox patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. No. 5,290,654, U.S. Pat. No. 5,278,020, U.S. Pat. No. 5,308,734, U.S. Pat. No. 5,370,963, U.S. Pat. No. 5,344,738, U.S. Pat. No. 5,403,693, U.S. Pat. No. 5,418,108, U.S. Pat. No. 5,364,729, and U.S. Pat. No. 5,346,797. Also of interest may be U.S. Pat. Nos. 5,348,832; 5,405,728; 5,366,841; 5,496,676; 5,527,658; 5,585,215; 5,650,255; 5,650,256 and 5,501,935.
In addition, the following U.S. Patents, the disclosures of which are incorporated herein by reference in their entireties, relate to processes for the preparation of toner compositions.
U.S. Pat. No. 5,922,501 illustrates a process for the preparation of toner comprising blending an aqueous colorant dispersion and a latex resin emulsion, and which latex resin can be generated from a dimeric acrylic acid, an oligomer acrylic acid, or mixtures thereof and a monomer; heating the resulting mixture at a temperature about equal, or about below the glass transition temperature (Tg) of the latex resin to form aggregates; heating the resulting aggregates at a temperature about equal to, or about above the Tg of the latex resin to effect coalescence and fusing of the aggregates; and optionally isolating the toner product, washing, and drying. U.S. Pat. No. 5,945,245 illustrates a surfactant free process for the preparation of toner comprising heating a mixture of an emulsion latex, a colorant, and an organic complexing agent.
U.S. Pat. No. 5,403,693 illustrates a process for the preparation of toner compositions with controlled particle size comprising (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.5 to about 10 percent by weight of water, and an optional charge control agent; (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of the ionic surfactant, a nonionic surfactant, and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin, and charge control agent; (iii) stirring the resulting sheared viscous mixture of (ii) at from about 300 to about 1,000 revolutions per minute to form electrostatically bound substantially stable toner size aggregates with a narrow particle size distribution; (iv) reducing the stirring speed in (iii) to from about 100 to about 600 revolutions per minute, and subsequently adding further anionic or nonionic surfactant to control, prevent, or minimize further growth or enlargement of the particles in the coalescence step (iii); and (v) heating and coalescing from about 5 to about 50° C. above about the resin glass transition temperature, Tg, which resin Tg is, for example, from between about 45° C. to about 90° C. and preferably from between about 50° C. and about 80° C. the statically bound aggregated particles to form a toner composition comprised of resin, pigment and optional charge control agent.
U.S. Pat. No. 5,482,812 illustrates a process for the preparation of toner compositions or toner particles comprising (i) providing an aqueous pigment dispersion comprised of a pigment, an ionic surfactant, and optionally a charge control agent; (ii) providing a wax dispersion comprised of wax, a dispersant comprised of nonionic surfactant, ionic surfactant or mixtures thereof; (iii) shearing a mixture of the wax dispersion and the pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of the ionic surfactant and a nonionic surfactant; (iv) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates; (v) adding additional ionic surfactant to the agg
Hopper Michael A.
Mychajlowskij Walter
Patel Raj D.
Martin Roland
Palazzo E. O.
Xerox Corporation
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