Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2000-08-24
2001-07-31
Goodrow, John (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
06268103
ABSTRACT:
BACKGROUND
This invention relates to toner and wax processes, and more specifically to the preparation of a surfactant free colorant, such as a pigment dispersion, wherein the colorant is melt blended into a wax that has been functionalized by the incorporation of from about 150 to about 600 of ionic groups such as carboxylic acid, sulfonate or phosphate groups resulting in an anionic functionality and an amino or amide groups with respect to cationic functionality to for example, allow the wax to be dispersable into a particulate aqueous dispersion when heated above room temperature in water at a pH value in the range of from about 2 to about 11 pH, wherein the resulting submicron particle size diameter is for example, in the range of about 80 to about 300 nanometers and wherein the colorant/wax particles are aggregated with a surfactant free latex containing submicron resin particles to provide toner compositions. More specifically, the present invention relates to a surfactant free chemical toner process wherein the process comprises (i) the preparation of an latex emulsion comprised of about 20 to about 50 weight percent of submicron resin particles in a diameter size range of, for example, from about 100 to about 300 nanometers suspended in an aqueous phase, such as water present, for example, in an amount of from about 80 to about 50 percent by weight, wherein the total amount of resin and water is about 100 percent and wherein the latex emulsion is surfactant free, (ii) preparing a wax which is functionalized with either anionic or cationic groups; (iii) melt blending this wax with a colorant to provide a colorant/wax mixture which is capable of being readily dispersable in warm water, for example from about 30 to about 50° C., at a suitable pH to provide a dispersion of submicron particles in the size range of about 50 to about 300 nanometers followed by aggregation and coalescence with the latex emulsion of (i) to provide a toner composition. The wax of (ii) utilized primarily to stabilize the colorant, such as pigment particles is for example, a polypropylene maleic anhydride with a saponification number of between about 42 and about 46, and which wax is capable of self dispersing in warm water, for example from about 30 to about 90° C., providing a submicron size dispersion. The resulting dispersion contains submicron wax particles suspended in water and wherein the wax possesses a diameter size of for example, in the range of about 80 to about 300 nanometers, wherein the dispersion comprises about 35 percent colorant, about 15 percent functionalized wax and about 50 percent water. More specifically, with the processes of the present invention an inorganic cationic metal salt can be selected as a coagulant to facilitate aggregation of the resin particles of the emulsion latex and submicron colorant particles stabilized by the functionalized wax by providing a coating or a shell on the colorant particles. With further respect to the processes of the present invention, there can be accomplished the staged increasing of the temperature during the coalescence wherein two or more heating temperatures are conducted to achieve the final coalescence to for example, retain the toner particle size distribution, followed by staged changing of the pH of the aggregate mixture wherein the pH is lowered in two or more sequences to, for example, provide toner processes which are surfactant free.
PRIOR ART
In forming toner compositions for use with reprographic or xerographic print devices, emulsion aggregation processes are known. For example, emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in a number of Xerox Corporation patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,370,963, 5,344,738, 5,403,693, 5,418,108, 5,364,729, and 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 forming toner compositions. U.S. Pat. No. 5,922,501 discloses a process for the preparation of toner by blending an aqueous colorant dispersion and a latex resin emulsion, and which latex resin is 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 below about the glass transition temperature (Tg) of the latex resin to form aggregates; heating the resulting aggregates at a temperature about equal to, or above about 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 certain complexing agents.
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 in the amount range of from about 0.1 to about 10 percent by weight of water to control, prevent, or minimize further growth or enlargement of the particles in the coalescence (iii); and (v) heating and coalescing from about 5° C. to 50° C. about above the resin glass transition temperature, Tg, which resin Tg is 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 said 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 with a narrow particle size distribution; (v) adding additional ionic surfactant to the aggregated suspension of (iv) to ensure that no, or minimal additional particle growth of the electrostatically bound toner size aggregates occurs on further increasing the temperature to coalesce the aggregates into toner particles (vi); (vi) heating the mixture of (v) with bound aggregates above about or at the Tg of the resin; and optionally (vii) separating the toner particles from the aqueous slurry by filtration and thereafter optionally washing.
U.S. Pat. No. 5,622,806 illustrates a process for the preparation of toner compositions with contr
Hopper Michael A.
Patel Raj D.
Goodrow John
Palazzo E. O.
Xerox Corporation
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