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Patent Issued for Curable Inks Comprising Surfactant-Coated Magnetic Nanoparticles

May 14, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Iftime, Gabriel (Mississauga, CA); Chopra, Naveen (Oakville, CA); Keoshkerian, Barkev (Thornhill, CA); Odell, Peter G. (Mississauga, CA); Breton, Marcel P. (Mississauga, CA), filed on March 17, 2011, was published online on April 29, 2014.

The assignee for this patent, patent number 8709274, is Xerox Corporation (Norwalk, CT).

Reporters obtained the following quote from the background information supplied by the inventors: "Non-digital inks and printing elements suitable for Magnetic Ink Character Recognition (MICR) printing are generally known. The two most commonly known technologies are ribbon-based thermal printing systems and offset technology. For example, U.S. Pat. No. 4,463,034 discloses heat sensitive magnetic transfer element for printing MICR, comprising a heat resistant foundation and a heat sensitive imaging layer. The imaging layer is made of ferromagnetic substance dispersed in a wax and is transferred on a receiving paper in the form of magnetic image by a thermal printer which uses a ribbon. U.S. Pat. No. 5,866,637 discloses formulations and ribbons which employ wax, binder resin and organic molecule based magnets which are to be employed for use with a thermal printer which employs a ribbon. MICR ink suitable for offset printing using a numbering box are typically thick, highly concentrated pastes consisting for example in about over 60% magnetic metal oxides dispersed in a base containing soy-based varnishes. Such inks are, for example, commercially available at Heath Custom Press (Auburn, Wash.). Digital water-based ink-jet inks composition for MICR applications using a metal oxide based ferromagnetic particles of a particle size of less than 500 microns are disclosed in U.S. Pat. No. 6,767,396. Water-based inks are commercially available from Diversified Nano Corporation (San Diego, Calif.).

"The present embodiments are directed to curable inks. Curable inks generally comprise at least one curable monomer, a colorant, and a radiation activated initiator that initiates polymerization of curable components of the ink. In particular, the curable ink is a ultraviolet (UV) curable liquid or gel ink. In particular, the curable ink is an ultraviolet (UV) curable ink. These UV curable liquid or gelink compositions can be used for ink jet printing in a variety of applications. In addition to providing desirable ink qualities, the present embodiments are directed to magnetic inks for use in specific applications. The UV curable ink of the present embodiments comprises magnetic nanoparticles that are coated with one or more surfactants to prevent the exposure of the nanoparticles to oxygen.

"UV curable gel inksare known. They are for example disclosed in, for example, U.S. Pat. Nos. 7,153,349, 7,259,275, 7,270,408, 7,271,284, 7,276,614, 7,279,506, 7,279,587, 7,293,868, 7,317,122, 7,323,498, 7,384,463, 7,449,515, 7,459,014, 7,531,582, 7,538,145, 7,541,406, 7,553,011, 7,556,844, 7,559,639, 7,563,489, 7,578,587, 7,625,956, 7,632,546, 7,674,842, 7,681,966, 7,683,102, 7,690,782, 7,691,920, 7,699,922, 7,714,040, 7,754,779, 7,812,064, and 7,820,731, the disclosures of each of which are totally incorporated herein by reference. UV curable gel inks can exhibit desirable characteristics such as improved hardness and scratch-resistance and improved adhesion to various substrates. UV curable gel inks can also exhibit advantages in that dot spread of the ink can be controlled, the ink does not bleed excessively into the substrate, including porous substrates.

"The present embodiments are directed to UV curable magnetic inks which comprise surfactant-coated metal nanoparticles. These magnetic inks are required for specific applications such as Magnetic Ink Character Recognition (MICR) for automated check processing and security printing for document authentication. One of the inherent properties of uncoated magnetic metal nanoparticles which precludes their use in the fabrication of commercial inks is their pyrophoric nature; uncoated (bare) magnetic nanoparticles of a certain size, typically in the order of a few tens of nanometers or less, ignite spontaneously when exposed to oxygen in the ambient environment. As such, uncoated magnetic metal nanoparticles are a serious fire hazard. As such, large scale production of the UV curable inks comprising such particles is difficult because air and water need to be completely removed when handling the particles. In addition, the ink preparation process is particularly challenging with magnetic pigments because inorganic magnetic particles are incompatible with organic base components.

"Thus, while the disclosed curable ink formulation provides some advantages over the prior formulations, there is still a need to achieve a formulation that not only provides the desirable properties of a curable ink and a curable liquid or gel UV ink in particular, but it is also magnetic. Furthermore there is a need to achieve a magnetic curable ink formulation that is easily produced and derived from components that do not require special handling conditions."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "According to embodiments illustrated herein, there is provided novel curable ink compositions comprising surfactant-coated magnetic metal nanoparticles. A particular embodiment provides gel UV curable ink compositions.

"In particular, the present embodiments provided an ink comprising: a curable ink carrier comprising a monomer, a photoinitiator, an optional curable oligomer, and one or more optional additives; coated magnetic nanoparticles, wherein the coated magnetic nanoparticles are comprised of a magnetic metal core and a protective coating disposed on the magnetic metal core, wherein the protective coating comprises one or more surfactants; and an optional colorant.

"In further embodiments, there is provided an ink comprising: a curable ink carrier comprising a monomer, a photoinitiator, an optional curable oligomer, and one or more optional additives; coated magnetic nanoparticles, wherein the coated magnetic nanoparticles are comprised of a magnetic metal core and a protective coating disposed on the magnetic metal core, wherein the protective coating comprises one or more surfactants; a gellant; and an optional colorant.

"In yet other embodiments, there is provided an ink comprising: a curable ink carrier comprising a monomer, a photoinitiator, an optional curable oligomer, and one or more optional additives; coated magnetic nanoparticles, wherein the coated magnetic nanoparticles are comprised of a magnetic metal core and a protective coating disposed on the magnetic metal core, wherein the protective coating comprises one or more surfactants; and an optional colorant, wherein the ink is used for Magnetic Ink Character Recognition applications."

For more information, see this patent: Iftime, Gabriel; Chopra, Naveen; Keoshkerian, Barkev; Odell, Peter G.; Breton, Marcel P.. Curable Inks Comprising Surfactant-Coated Magnetic Nanoparticles. U.S. Patent Number 8709274, filed March 17, 2011, and published online on April 29, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=99&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4938&f=G&l=50&co1=AND&d=PTXT&s1=20140429.PD.&OS=ISD/20140429&RS=ISD/20140429

Keywords for this news article include: Nanotechnology, Xerox Corporation, Metal Nanoparticles, Emerging Technologies.

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Source: Journal of Engineering


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