Coating processes – Particles – flakes – or granules coated or encapsulated – Resin base
Reexamination Certificate
2000-12-06
2001-07-03
Goodrow, John (Department: 1753)
Coating processes
Particles, flakes, or granules coated or encapsulated
Resin base
Reexamination Certificate
active
06254929
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to methods for controllably coating the surfaces of particles with smaller sized colloidal particles. More specifically the present invention relates to processes for forming colloidal particles of useful surface additives, such as an organocarboxylate metal salt and other lubricant or release agent additives, on the surface of suspended resin particles, such as toner particles.
The present invention in turn provides improved toner compositions and imaging processes thereof. The imaging processes of the present invention provide toners and methods of preventing or eliminating background deposits and spotted images and which spots are believed to arise from fugitive aforementioned lubricant or release agent additives that have escaped from the surface of the toner resin particles and result in objectionable deposits in the developer housing, on the imaging member, and on the image itself.
The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics, maintain their triboelectric charging characteristics for an extended number of imaging cycles, and enable the elimination or minimization of undesirable background deposits or spots on the imaging member or photoconductor, and the image receiver sheet or copy paper. Furthermore, the toner compositions of the present invention are substantially insensitive to relative humidity in a machine environment and permit developed images with excellent optical densities and low background. Developers of the present invention are comprised of the aforementioned toners and carrier particles, especially carrier particles comprised of a core with a mixture of polymers thereover. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic and ionographic, imaging and printing processes and preferably ionographic version of magnetic image character recognition processes (MICR) such as processes similar to those selected for the Xerox Corporation 8790/9790 MICR machines, and preferably the Xerox Corporation 4135® MICR test fixture or machine, and wherein for example, personal checks with no, or minimal background deposits can be generated.
PRIOR ART
In U.S. Pat. No. 4,507,378, to Wada et al., issued Mar. 26, 1985, there is disclosed a method for producing a toner by polymerizing an aqueous suspension of a monomer in the presence of a dispersant selected from orthophosphate, pyrophosphate and polyphosphate, a colorant and an anionic surfactant. The polymerization product is then treated with dilute acid and rinsed with water whereby the dispersant is removed from the polymerization product.
In U.S. Pat. No. 4,476,210, to Croucher et al., there is disclosed a liquid developer comprising an amphipathic stabilizer polymer irreversibly anchored to a thermoplastic resin core of marking particles. The stabilizer has a soluble polymer backbone with an insoluble anchoring chain grafted onto the polymer backbone. The stabilizer may comprise an AB or ABA type block copolymer. The block copolymers may include siloxanes. The procedure for preparing the liquid developer comprises the steps of (1) preparation of the amphipathic stabilizer; (2) non-aqueous dispersion polymerization of the core monomer in the presence of the amphipathic stabilizer to provide stabilized particles; (3) dyeing of the non-aqueous dispersion particles; and (4) negatively charging the particles.
U.S. Pat. No. 6,020,101, issued Feb. 1, 2000, to Sacripante, et al., discloses a toner comprised of a core comprised a first resin and colorant, and thereover a shell comprised of a second resin and wherein the first resin is an ion complexed sulfonated polyester resin, and the second resin is a transition metal ion complex sulfonated polyester resin.
U.S. Pat. No. 6,017,668, issued Jan. 25, 2000, to Young, et al., discloses a toner comprised of resin, colorant, and a surface additive mixture of a magnetite and a polyvinylidene fluoride.
U.S. Pat. No. 3,900,588, issued Aug. 19, 1975, to Fisher et al., discloses an imaging technique and composition for developing electrostatographic latent images whereby a developer composition is employed comprising toner, a substantially smearless polymeric additive like KYNAR®, and an abrasive material surface additive such as silica, like AEROSIL R972®, or strontium titanate, see column 7, lines 12 to 17.
U.S. Pat. No. 5,437,955, issued Aug. 1, 1995, to Michlin, discloses a dry toner composition for electrophotography including a binder resin, a coloring agent and a mica-group mineral, which mineral provides the toner composition with lubricity and better flow capabilities. The mica-group mineral is wet ground and may be coated with calcium stearate to reduce static electricity generated during operation of the electrophotographic machine.
U.S. Pat. No. 4,395,485, issued Jul. 26,1983, to Kashiwage, et al., discloses a one component type dry developer for electrophotography which is improved on humidification, and consists of a mixture of toner with a particle size of about 5 to 50 microns and a hydrophobic flow agent. The flow agent is made by coating inorganic, organic, metallic or an alloy powder with a thin film of non-hydrophilic synthetic resin. A flow agent having non-hydrophilic and electrically conductive properties is obtained.
U.S. Pat. No. 4,748,474, issued May 31, 1988, to Karematusu, et al., discloses an imaging forming method and apparatus using an image bearing member, movable along an endless path, for bearing a toner image and having a critical surface tension of not more than 33 dyne/cm, wherein the toner image formed on the image bearing member by a developer containing toner not less than 70% of which has a particle size of 1-5 microns, and lubricant in an amount not less than 0.5% by weight of the toner, and the image bearing member is cleaned by removing the toner image remaining on the image bearing member.
U.S. Pat. No. 5,079,123, issued Jun. 7, 1992, to Nanya, et al., discloses a dry-type toner for electrophotography comprising a binder resin, a coloring agent, and, as a lubricant, a carnauba wax substantially free of free aliphatic acids. The toner may further comprised a magnetic material, and the resulting toner mixture can be used as a magnetic toner.
U.S. Pat. No. 6,017,671, issued Jan. 25, 2000, to Sacripante, et al., a toner composition comprised of a polyester resin with hydrophobic end groups, colorant, optional wax, optional charge additive, and optional surface additives.
The aforementioned patents are incorporated in their entirety by reference herein.
Other patents of interest follow. The following U.S. Patents disclose the addition of zinc stearate to the surface of toners by blending to control the toner resistivity and in some instances to provide for toner release in the developer: U.S. Pat. Nos. 5,043,240; 5,045,428; 5,135,832; and 5,023,159. Toners and developers with surface additives of metal salts of fatty acids like zinc stearate and silica are known, reference for example U.S. Pat. Nos. 3,983,045 and 3,590,000. The commonly owned and assigned U.S. Pat. No. 3,983,045, issued Sep. 28, 1976, to Jugle et al., discloses a developer composition comprising 1) electroscopic toner particles, 2) a friction-reducing material, such as fatty acids, metal salts of fatty acids, fatty alcohols, fluorocarbon compounds, polyethylene glycols, and the like, of a hardness less than the toner and having greater friction-reducing characteristics than the toner material, and 3) a finely divided nonsmearable abrasive material, such as, colloidal silica, surface modified silica, titanium dioxide, and the like metal oxides, of a hardness greater than the friction-reducing and toner material. In U.S. Pat. No. 4,789,613, there is illustrated a toner with an effective amount of, for example, strontium titanate dispersed therein, such as from about 0.3 to about 50 weight percent. Also disclosed in the '613 patent is the importance of the dielectric material with
Duff James M.
Kmiecik-Lawrynowicz Grazyna E.
Sacripante Guerino G.
Goodrow John
Haack John
Palazzo E. O.
Xerox Corporation
LandOfFree
Particulate surface treatment process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Particulate surface treatment process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Particulate surface treatment process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550635