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
2001-02-20
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...
C430S137170, C430S109500
Reexamination Certificate
active
06190815
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 coated silica surface additives. The coated silicas are available from Cabosil, and more specifically these silicas preferably possess a primary particle size of about 25 nanometers to about 55 nanometers and an aggregate size of about 225 nanometers to about 400 nanometers. With the toners of the present invention, in embodiments thereof a number of advantages are achievable, such as excellent stable triboelectric charging characteristics, substantial insensitivity to humidity, especially humidities of from about 20 to about 80 weight percent, superior toner flow through, acceptable triboelectric charging values, such as from about 15 to about 55 microcoulombs per gram as determined, for example, by the known Faraday Cage, and wherein the toners enable the generation of developed images with superior resolution, and excellent color intensity. The aforementioned toner compositions can contain colorants, such as dyes or pigments comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof, thereby providing for the development and generation of black and/or colored images, and in embodiments the toner can be selected for two component development and single component development wherein a carrier or carrier particles are avoided.
The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including color, digital processes, and multisystems apparatus and machines.
PRIOR ART
Toner compositions with certain surface additives, including certain silicas, are known. Examples of these additives include colloidal silicas, such as certain AEROSILS like R972® available from Degussa, metal salts and metal salts of fatty acids inclusive of zinc stearate, aluminum oxides, cerium oxides, and mixtures thereof, which additives are each generally present in an amount of from about 1 weight percent by weight to about 5 weight percent by weight, and preferably in an amount of from about 1 weight percent by weight to about 3 weight percent by weight. Several 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 a mixture of hexamethyldisilazane (HMDZ) and APTES, an aminopropyltriethoxysilane.
Further, toner compositions with charge enhancing additives, which impart a positive charge to the toner resin, 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, reference the Abstract of the Disclosure and column 3; 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 applying 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 documents 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 '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 '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 which contains a metal complex represented by the formula in column 2, for example, and wherein ME can be chromium, cobalt or iron. Additionally, other patents disclosing various metal containing azo dyestuff structures wherein the metal is chromium or cobalt include U.S. Pat. Nos. 2,891,939; 2,871,233; 2,891,938; 2,933,489; 4,053,462 and 4,314,937. 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. These and other charge enhancing additives, such as these illustrated in U.S. Pat. Nos. 5,304,449, 4,904,762, and 5,223,368, the disclosures of which are totally incorporated herein by reference, 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 a mixture of certain surface additives, and wherein the toners possess a number of advantages.
In another feature of the present invention there are provided negatively charged toner compositions useful for the development of electrostatic latent images including color images.
In yet another feature of the present invention there are provided negatively charged toner compositions useful for the development of electrostatic latent images including full process color images.
In another feature of the present invention there are provided toner surface additives that enable fast toner admix as measured by a charge spectrograph.
Also, in another feature of the present invention there are provided coated silica surface additives that enable toner unimodal charge distribution as measured by a charge spectrograph.
Further, in another feature of the present invention there are provided certain surface additives that enable an unimodal charge distribution upon admix of fresh toner into aged toner as measured by a charge spectrograph.
Other features of the present invention include providing toner and developer compositions with a mixture of certain surface additives that enable acceptable high stable triboelectric charging characteristics from for example about 15 to about 60 microcoulombs per gram, and preferably from about 25 to about 40 microcoulombs per gram; toner and developer compositions wit
Bayley Denise R.
Bertrand Jacques C.
Ciccarelli Roger N.
Combes James R.
Pickering Thomas R.
Palazzo E. O.
Rodee Christopher D.
Xerox Corporation
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