Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2002-03-25
2003-09-09
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S106200
Reexamination Certificate
active
06617092
ABSTRACT:
BACKGROUND
The present invention relates to toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner compositions containing magnetite. More specifically, the present invention in embodiments relates to processes for the preparation of a toner composition by a chemical process, such as emulsion aggregation, wherein latex particles are aggregated with colorant particles, such as magnetite or iron oxides, and wherein such particles can simultaneously function as colorant particles and as a coagulating or flocculating agent, and thereafter coalescing or fusing to provide toner size particles which when developed by an electrographic process generates documents suitable for magnetic image character recognition or MICR. The use of iron oxide particles, which can exhibit a positive of about +10 to about −40 coulombs per square centimeter (coulombs/cm
2
) at low pH conditions, such as for example, from about 1.5 to about 5 and a charge of about −2 to about −40 coulombs/cm
2
at a high pH, such as for example about 6.5 to about 10, permits such particles to function as coagulating or flocculating agents for anionically charged species and catatonically charged species, respectively.
REFERENCES
In U.S. Pat. No. 6,132,924, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant a latex, and a coagulant, followed by aggregation and coalescence, wherein the coagulant may be a polyaluminum chloride.
In U.S. Pat. No. 6,268,102, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant, a latex, and a coagulant, followed by aggregation and coalescence wherein the coagulant may be a polyaluminum sulfosilicate.
Illustrated in U.S. Pat. No. 5,994,020, the disclosure of which is totally incorporated herein by reference, are toner preparation processes, and more specifically, a process for the preparation of toner comprising
(i) preparing, or providing a colorant dispersion;
(ii) preparing, or providing a functionalized wax dispersion comprised of a functionalized wax contained in a dispersant mixture comprised of a nonionic surfactant, an ionic surfactant, or mixtures thereof;
(iii) shearing the resulting mixture of the functionalized wax dispersion (ii) and the colorant dispersion (i) with a latex or emulsion blend comprised of resin contained in a mixture of an anionic surfactant and a nonionic surfactant;
(iv) heating the resulting sheared blend of (iii) below about the glass transition temperature (Tg) of the resin particles;
(v) optionally adding additional anionic surfactant to the resulting aggregated suspension of (iv) to prevent, or minimize additional particle growth of the resulting electrostatically bound toner size aggregates during coalescence (iv);
(vi) heating the resulting mixture of (v) above about the Tg of the resin; and optionally,
(vii) separating the toner particles.
With respect to the references, only a small part thereof has been selected and this part may or may not be fully representative of the prior art teachings or disclosures.
Magnetic ink printing methods with inks containing magnetic particles are known. For example, there is disclosed in U.S. Pat. No. 3,998,160 that various magnetic. inks have been used in printing digits, characters, or artistic designs, on checks or bank notes. The magnetic ink used for these processes contains, for example, acicular magnetic particles, such as magnetite in a fluid medium, and a magnetic coating of ferric oxide, chromium dioxide, or similar materials-dispersed in a vehicle of binders, and plasticizers. Disclosed in U.S. Pat. No. 4,128,202 is a device for transporting a document that has been mutilated or erroneously encoded, and wherein there is provided a predetermined area for the receipt of correctly encoded magnetic image character recognition information (MICR). As indicated in this patent, the information involved. is referred to as MICR characters, which characters appear, for example, at the bottom of personal checks as printed numbers and symbols. These checks can be printed in an ink containing magnetizable particles therein, and when the information contained on the document is to be read, the document is passed through a sorter/reader which first magnetizes the magnetizable particles, and subsequently detects a magnetic field of the symbols resulting from the magnetic retentivity of the ink. The characters and symbols involved, according to the '202 patent are generally segregated into three separate fields, the first field being termed a transient field, which contains the appropriate symbols and characters to identify the bank, bank branch, or the issuing source. The second field contains the account affected by the transactions, and the third field, which is not prerecorded, indicates the amount of the check.
In U.S. Pat. No. 5,914,209, the disclosure of which is totally incorporated by reference, there is illustrated a process of preparing MICR toners using a combination of hard and soft magnetites and lubricating, and melt mixing this combination with a resin followed by jetting and classifying the blend to provide toner compositions.
In U.S. Pat. No. 4,517,268, the disclosure of which is totally incorporated by reference, there is illustrated a process for the preparation of MICR toners by melt mixing the appropriate components in a Banbury apparatus, following by pulverizing the magnetite and the resin, and then jetting and classifying to provide, for example, about 10 to about 12 micron toner size particles, which when mixed with an additive package and carrier can provide a developer suitable for the Xerox Corporation 9700®.
Other patents relating to MICR processes include U.S. Pat. Nos. 4,859,550; 5,510,221, and 5,034,298.
In U.S. Pat. No. 5,780,190 there is disclosed an ionographic process which comprises the generation of a latent image comprised of characters; developing the image with an encapsulated magnetic toner comprised of a core comprised of a polymer and soft magnetite, and wherein the core is encapsulated within a polymeric shell; and subsequently providing the developed image with magnetic ink characters thereon to a reader/sorter device.
Illustrated in U.S. Pat. No. 4,758,506, the disclosure of which is, totally incorporated herein by reference, are single component development cold pressure fixable toner compositions, wherein the shell selected can be prepared by an interfacial polymerization process. Also known are single component magnetic cold pressure fixable toner compositions comprised of magnetite and a polyisobutylene encapsulated in a polymeric shell material generated by an interfacial polymerization process.
In applications requiring MICR capabilities, the toners selected usually contain magnetites having specific properties, an important one of which is a high enough level of remanence or retentivity. Retentivity is a measure of the magnetism remaining when the magnetite is removed from the magnetic field, i.e. the residual magnetism. Also, of interest is a high retentivity such that when the characters are read, the magnetite produces a sufficient signal strength. The magnetic signal level is of value in MICR systems, and the signal level can vary in proportion to the amount of toner deposited on the document being generated; the signal strength of the toner composition can be measured by using known devices, including the MICR-Mate 1, manufactured by Checkmate Electronics, Inc.
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 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.
Hopper Michael A.
Patel Raj D.
Goodrow John
Palazzo E. O.
Xerox Corporation
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