Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1998-08-11
2001-04-10
Rodee, Christopher D. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
Reexamination Certificate
active
06214507
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to positively, or negatively charged toner compositions, or toner particles containing certain additives of silicas especially coated fumed silica surface additives, and wherein the additives selected are for example, of a large size diameter of from about 20 nanometers to about 100 nanometers, preferably from about 30 to about 50 nanometers and more preferably in embodiments about 40 nanometers in diameter. With the toners of the present invention, in embodiments thereof a number of advantages are achievable, such as excellent triboelectric charging characteristics, substantial insensitivity to relative humidity, especially humidities of from about 20 to about 80 percent, superior toner flow through, high stable triboelectric charging values, such as from about 15 to about 35 and more specifically from about 16 to about 24 microcolumbs per gram as determined for example, by the known tribo blow-off technique using a Faraday cage and wherein the toners enable the generation of developed images with superior resolution, and excellent color intensity. Important advantages associated with the toners of the present invention is the enablement of high transfer image efficiencies of, for example, greater than about 90 percent, and more specifically from about 90 percent to about 97 percent, and yet more specifically from about 90 to about 95 percent, and excellent image developability wherein images with high resolution, substantially no defects, such as scratches, non-uniform image density, and excellent optical densities determined by a Macbeth 1200 series optical densitometer, such as from about 1.2 to about 1.4 or greater are obtainable.
The aforementioned toner compositions can contain colorants, such as pigment particles comprised of, for example, carbon black, magnetite's, or mixtures thereof, cyan, magenta, yellow, blue, green, red, brown, or white components, or mixtures thereof, thereby providing for the development and generation of black and/or colored images, and in embodiments single component development wherein a carrier or carrier particles are avoided. Thus, the toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including color and digital processes.
PRIOR ART
Toner compositions with certain surface additives, including certain silicas and titanias, are known. Examples of these additives include colloidal silicas, with a coating of dichlorodimethylsilane, such as certain coated AEROSILS like R972® available from Degussa Chemicals, which silicas are of a small size, that is from about 8 to about 16 nanometers, metal salts and metal salts of fatty acids inclusive of zinc stearate, aluminum oxides, cerium oxides, titanium oxides and mixtures thereof, which additives are each generally present in an amount of from about 1 percent by weight to about 7 percent by weight, and preferably in an amount of from about 1 percent by weight to about 6 percent by weight. A number of the aforementioned additives are illustrated in U.S. Pat. Nos. 3,590,000 and 3,900,588, the disclosures of which are totally incorporated herein by reference.
Also known are toners containing additives of certain characteristics, such as a small size, coated with a mixture of hexamethyidisilazane (HMDZ), and aminosiloxanes. Problems with these toners include their high cost, small size, and a low triboelectric charge of for example, from about 10 to about 15 microcoulombs per gram (&mgr;C/g) and relative humidity sensitivity. These and other disadvantages are avoided or minimized with the toners of the present invention. More specifically, advantages achievable with the toners of the present invention as compared to this prior art include minimal impact on the toner fusing properties, excellent admix charging characteristics, for example from about 15 to about 30 seconds, stable development performance, lower cost, and superior image transfer efficiency of the developed toner image.
Developer compositions with charge enhancing additives, which impart a positive charge to the toner particle, are also known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions. U.S. Pat. No. 4,221,856 discloses electrophotographic toners containing resin compatible quaternary ammonium compounds in which at least two R radicals are hydrocarbons having from 8 to about 22 carbon atoms, and each other R is a hydrogen or hydrocarbon radical with from 1 to about 8 carbon atoms, and A is an anion, for example sulfate, sulfonate, nitrate, borate, chlorate, and the halogens, such as iodide, chloride and bromide, and a similar teaching is presented in U.S. Pat. No. 4,312,933, which is a division of U.S. Pat. No. 4,291,111; and similar teachings are presented in U.S. Pat. No. 4,291,112 wherein A is an anion including, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with certain finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by using a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica.
Also, there is disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can impart a positive charge to the toner composition. Further, there is disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles and pigment particles, and as charge enhancing additives alkyl pyridinium compounds. Additionally, other patents disclosing positively charged toner compositions with charge control additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,430 and 4,560,635 which illustrates a toner with a distearyl dimethyl ammonium methyl sulfate charge additive.
Moreover, toner compositions with negative charge enhancing additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The U.S. Pat. No. 4,411,974 patent discloses negatively charged toner compositions comprised of resin particles, pigment particles, and as a charge enhancing additive ortho-halo phenyl carboxylic acids. Similarly, there are disclosed in the U.S. Pat. No. 4,206,064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing additives.
There is illustrated in U.S. Pat. No. 4,404,271 a toner composition for developing electrostatic images in which the toner contains a metal complex represented by the formula indicated therein and wherein the metal, ME, can be chromium, cobalt or iron. Also, in U.S. Pat. No. 4,433,040, the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions with chromium and cobalt complexes of azo dyes as negative charge enhancing additives. Toners with aluminum complex charge additives are illustrated in U.S. Pat. Nos. 5,324,613 and 5,223,368, the disclosures of each of these patent being totally incorporated herein by reference.
The above components, such as the charge additives may be selected for the present invention in embodiments thereof.
SUMMARY OF THE INVENTION
Examples of features of the present invention in embodiments thereof include:
It is a feature of the present invention to provide toner and developer compositions with certain surface additives, and wherein the ton
Gutman Edward J.
Sokol Jeffrey H.
Oliff & Berridg,e PLC
Palazzo Eugene O.
Rodee Christopher D.
Xerox Corporation
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