Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-03-26
2003-07-15
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108110
Reexamination Certificate
active
06593049
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing charge enhancing additives, which impart or assist in imparting a negative charge to the toner resin particles and enable in embodiments toners with rapid admix characteristics. In embodiments, there are provided in accordance with the present invention toner compositions comprised of resin particles, colorant particles, and a charge additive of a metal complex comprised, for example, of a hard acid metal ion, such as aluminum with a valence of three, zinc with a valence of two, and a hard base, such as sulfate, acetate, phosphate, and the like. Hard acid refers, for example, to a Lewis acid comprised of an electron-accepting ion or group with a softness character that is, for example, an intrinsic quantity calculated on properties of ions, such as ionization potential, electron affinity, and size, as illustrated by G. Klopman in the R. G. Pearson reference mentioned herein, the disclosure of which is totally incorporated herein by reference, and which softness is, for example, from about 0.0 eV (electron volts) to 7 eV and, more specifically, from about 1 eV to 6.1 eV, including for example, ions of Li
+
(lithium+1 ion), Na
+
(sodium +1 ion), K
+
(potassium +1 ion), Mg
2+
(magnesium +2 ion), Ca
2+
(calcium +2 ion), Ce
4+
(cerium +4 ion), Ti
4+
(titanium +4 ion), Cr
3+
(chromium +3 ion), Fe
3+
(iron +3 ion), Co
3+
(cobalt +3 ion), BF
3
(boron fluoride), Al
3+
(aluminum +3 ion), Sn
4+
(tin +4 ion), HX where X is a heteroatom-containing group such as NH
3
, OH, and the like, as illustrated in a monograph authored by R. G. Pearson, “
Hard and Soft Acids and Bases
”, Dowden, Hutchinson and Roe: Stroudsburg, Pa. 1973, the disclosure of which is totally incorporated herein by reference. Hard base refers, for example, to a Lewis base comprised of an electron-donating ion or group with a softness character of, for example, from about −8.5 eV to about −13 and, more specifically, from about −9 eV to about −12.2 eV or with a softness number that is, for example, the reaction rate with dichlorobis(pyridine)platinum II, Pt(C
5
H
5
N)
2
Cl
2
, as illustrated in the referenced R. G. Pearson reference, of from about 0.0 to about 4.4 and, more specifically, from about 0.0 to about 2.5 and which hard bases include, for example, NH
3
(ammonia), OH
−
(hydroxide), NO
2
−
(nitrite), CH
3
CO
2
−
(acetate), CO
3
2−
(carbonate), NO
3
−
(nitrate), PO
4
3−
(phosphate), SO
4
2−
(sulfate), ClO
4
−
(perchlorate), F
−
(fluoride), and Cl
−
(chloride).
The charge additives in embodiments of the present invention enable, for example, toners with rapid admix of less than about 15 seconds, high triboelectric charging values, such as for example, from about 35 to about 60 and preferably from about 40 to about 50 microcoulombs per gram as measured by the known charge spectrograph, or by the known Faraday cage method, extended developer life, stable electrical properties, high image print quality with substantially no background deposits, improved RH sensitivity especially for polyester toners, and compatibility with fuser rolls including VITON fuser rolls. Also, the aforementioned toner compositions, usually colorless, can be rendered colored with colorant particles 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. The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics as indicated herein, and maintain their triboelectric charging characteristics for an extended number of imaging cycles, exceeding, for example, about 1,000,000 in a number of embodiments. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including color processes, and more specifically, for the Xerox Corporation 265 machine.
PRIOR ART
Developer compositions with charge enhancing additives, which impart a positive charge to the toner resin, are known. Thus, for example, there is described in U.S. Pat. No. 3,893,935, the disclosure of which is totally incorporated herein by reference, the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions. In this patent, there are disclosed quatemary ammonium compounds with four R substituents on the nitrogen atom, which substituents represent an aliphatic hydrocarbon group having 7 or less, and preferably about 3 to about 7 carbon atoms, including straight and branch chain aliphatic hydrocarbon atoms, and wherein X represents an anionic function including, according to this patent, a variety of conventional anionic moieties such as halides, phosphates, acetates, nitrates, benzoates, methylsulfates, perchloride, tetrafluoroborate, benzene sulfonate, and the like; U.S. Pat. No. 4,221,856, the disclosure of which is totally incorporated herein by reference, which 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; 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, the disclosures of which are totally incorporated herein by reference; and similar teachings are presented in U.S. Pat. No. 4,291,112, the disclosure of which is totally incorporated herein by reference, 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, the disclosure of which is totally incorporated herein by reference, reversal developer compositions comprised of toner resin particles coated with 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 colorant 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, the disclosures of which are totally incorporated herein by reference, which illustrates a toner with a distearyl dimethyl ammonium methyl sulfate charge additive.
The following prior art, all United States patents, was located in a search for toners with charge additives: U.S. Pat. No. 4,812,381, the disclosure of which is totally incorporated herein by reference, which discloses toners and developers containing charge control agents comprising quaternary ammonium salts of the formula indicated, for example, in the Abstract of the Disclosure, wherein R is alkyl with f
Carlini Rina
Sacripante Guerino G.
Stegamat Reza
Veregin Richard P. N.
Chapman Mark A.
Palazzo E. O.
Xerox Corporation
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