USOO8409341B2
`
`(12) United States Patent
`Iftime et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,409,341 B2
`*Apr. 2, 2013
`
`(54)
`
`(75)
`
`(73)
`(*)
`
`(21)
`(22)
`(65)
`
`(51)
`
`(52)
`
`(58)
`
`SOLVENT-BASED INKS COMPRISING
`COATED MAGNETICNANOPARTICLES
`
`Inventors: Gabriel Iftime, Mississauga (CA); Peter
`G. Odell, Mississauga (CA); C.
`Geoffrey Allen, Waterdown (CA);
`Marcel P. Breton, Mississauga (CA);
`Richard P. N. Veregin, Mississauga
`(CA)
`Assignee: Xerox Corporation, Norwalk, CT (US)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 39 days.
`This patent is Subject to a terminal dis
`claimer.
`
`Appl. No.: 13/050,223
`
`Filed:
`
`Mar 17, 2011
`
`Prior Publication Data
`US 2012/O235074 A1
`Sep. 20, 2012
`
`Int. C.
`(2006.01)
`C09D II/00
`U.S. Cl. ................... 106/31.6; 106/31.9; 106/31.65;
`106/31.92
`Field of Classification Search ................. 106/31.6,
`106/31.65, 31.9, 31.92
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,463,034 A
`7, 1984 Tokunaga et al.
`5,866,637 A
`2f1999 Lorenz
`6.262,129 B1* 7/2001 Murray et al. .................. 516.33
`6,767,396 B2
`7/2004 McElligottet al.
`7,407,572 B2
`8, 2008 Steffenset al.
`2006/0003163 A1* 1/2006 Mayes .......................... 428/407
`2007/0249747 A1 10/2007 Tsuji et al.
`2009/0321676 A1 12/2009 Breton et al.
`2010, OO15472 A1
`1/2010 Bradshaw et al.
`2010.0060539 A1
`3/2010 SuetSuna et al. .............. 343,787
`2010/0292467 A1 11/2010 Goredema et al.
`2010/0304006 Al 12/2010 Delpechet al.
`FOREIGN PATENT DOCUMENTS
`WO WO 2008148201 A1 * 12/2008
`* cited by examiner
`Primary Examiner — Kaj K Olsen
`Assistant Examiner — Veronica F Faison
`(74) Attorney, Agent, or Firm — Pillsbury Winthrop Shaw
`Pittman LLP
`
`ABSTRACT
`(57)
`Solvent-based ink compositions which can be used for inkjet
`printing in a variety of applications. In particular, the present
`embodiments are directed to magnetic inks having desirable
`ink properties. The ink of the present embodiments comprise
`magnetic nanoparticles that are coated with various materials
`to prevent the exposure of the nanoparticles to oxygen, and
`provides robust prints.
`
`19 Claims, 1 Drawing Sheet
`
`5
`
`
`
`Ex.1027 / IPR2022-00117 / Page 1 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`U.S. Patent
`
`Apr. 2, 2013
`
`US 8,409,341 B2
`
`
`
`Ex.1027 / IPR2022-00117 / Page 2 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`1.
`SOLVENT-BASED INKS COMPRISING
`COATED MAGNETICNANOPARTICLES
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`10
`
`15
`
`Reference is made to commonly owned and co-pending,
`U.S. patent application Ser. No. 13/050,268 entitled “Curable
`Inks Comprising Inorganic Oxide-Coated Magnetic Nano
`particles' to Iftime et al.; U.S. patent application Ser. No.
`13/050,152 entitled “Solvent-Based Inks Comprising Coated
`Magnetic Nanoparticles' to Iftime et al.; U.S. patent applica
`tion Ser. No. 13/050,403 entitled “Magnetic Curable Inks' to
`Iftime et al.: U.S. patent application Ser. No. 13/049,936
`entitled “Phase Change Magnetic Ink Comprising Carbon
`Coated Magnetic Nanoparticles And Process For Preparing
`Same to Iftime et al.; U.S. patent application Ser. No.
`13/049,937 entitled “Solvent Based Magnetic Ink Compris
`ing Carbon Coated Magnetic Nanoparticles And Process For
`Preparing Same to Iftime et al.; U.S. patent application Ser.
`No. 13/049,942 entitled “Phase Change Magnetic Ink Com
`prising Coated Magnetic Nanoparticles And Process For Pre
`paring Same' to Iftime et al. U.S. patent application Ser. No.
`13/049.945 entitled “Phase Change Magnetic Ink Compris
`ing Inorganic Oxide Coated Magnetic Nanoparticles And
`25
`Process For Preparing Same to Iftime et al.; U.S. patent
`application Ser. No. 13/050,341 entitled “Curable Inks Com
`prising Surfactant-Coated Magnetic Nanoparticles' to Iftime
`et al.; U.S. patent application Ser. No. 13/050,383 entitled
`“Curable inks Comprising Polymer-Coated Magnetic Nano
`30
`particles' to Iftime et al.; U.S. patent application Ser. No.
`13/049.950entitled “Phase Change Magnetic Ink Comprising
`Surfactant Coated Magnetic Nanoparticles and Process For
`Preparing the Same' to Iftime et al.; and U.S. patent applica
`tion Ser. No. 13/049,954 entitled “Phase Change Magnetic
`Ink Comprising Polymer Coated Magnetic Nanoparticles and
`Process for Preparing the Same to Iftime at al., all filed
`electronically on the same day as the present application, the
`entire disclosures of which are incorporated herein by refer
`ence in its entirety.
`
`35
`
`40
`
`BACKGROUND
`
`Non-digital inks and printing elements Suitable for Mag
`netic Ink Character Recognition (MICR) printing are gener
`45
`ally 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 dis
`persed 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 mol
`ecule 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 contain
`60
`ing Soy-based varnishes. Such inks are, for example, com
`mercially available at Heath Custom Press (Auburn, Wash.).
`Digital water-based ink-jet inks composition for MICR appli
`cations 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.).
`
`50
`
`55
`
`65
`
`US 8,409,341 B2
`
`2
`The present embodiments relate to solvent-based ink com
`positions. These ink compositions can be used for inkjet
`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 ink of
`the present embodiments comprise magnetic nanoparticles
`that are coated with various materials to prevent the exposure
`of the nanoparticles to oxygen. The present embodiments are
`also directed to a solvent-based magnetic ink that provides
`robust prints.
`The present embodiments are directed to solvent-based
`magnetic inks which comprise an organic solvent, an optional
`dispersant, an optional Synergist, an optional antioxidant, an
`optional viscosity controlling agent, an optional colorant, and
`coated magnetic nanoparticles comprising a magnetic core
`and a coated shell disposed thereover. These magnetic inks
`are required for specific applications such as Magnetic Ink
`Character Recognition (MICR) for automated check process
`ing and security printing for document authentication. One of
`the challenges in formulating Such a solvent-based ink, how
`ever, is that many of these metal nanoparticles are pyrophoric
`and extremely sensitive to air and water. For example, iron
`nanoparticles can burst into flame instantly upon exposure to
`air. As such, uncoated magnetic metal nanoparticles are a
`serious fire hazard. As such, large scale production of the
`Solvent-based 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. Lastly, a problem associated with the use of
`the magnetic solid inks is the solid ink vehicle is designed for
`normal office use and not the highly abrasive environment of
`multiple passes through a magnetic reader. As a result, a
`magnetic Solid ink print may wear off quickly during
`machine-reading process, either for MICR or for document
`authentication procedures.
`Thus, there is a need for a magnetic ink which can be
`printed with piezoelectric print-heads and which can be made
`both safely and provides robust prints compatible with sol
`Vent-based compositions.
`Thus, while the disclosed solid 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 solvent-based ink but is also more
`easily produced and derived from components that do not
`require special handling conditions.
`
`SUMMARY
`
`According to embodiments illustrated herein, there are
`provided solvent-based ink compositions which produce
`robust prints and which can be used for inkjet printing in a
`variety of applications. The ink of the present embodiments
`comprise magnetic nanoparticles that are coated with various
`materials, such as for example, polymers, Surfactants and
`inorganic oxides, to prevent the exposure of the nanoparticles
`to oxygen. The present embodiments are also directed to a
`Solvent-based magnetic ink that provides robust prints.
`In particular, the present embodiments provide a magnetic
`ink comprising: an organic solvent carrier; an optional dis
`persant; an optional Synergist; an optional antioxidant; an
`optional viscosity controlling agent; an optional colorant; an
`optional binder; and coated magnetic nanoparticles, wherein
`the coated magnetic nanoparticles are comprised of a mag
`netic metal core and a protective coating disposed on the
`magnetic metal core, the coated magnetic nanoparticles being
`
`Ex.1027 / IPR2022-00117 / Page 3 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`US 8,409,341 B2
`
`3
`dispersed in the solvent carrier and further wherein the pro
`tective coating is selected from the group consisting of poly
`meric materials, inorganic oxides, Surfactants and mixtures
`thereof.
`In further embodiments, there is provided a magnetic ink
`comprising: a solvent carrier, an optional dispersant; an
`optional synergist; an optional antioxidant; an optional vis
`cosity controlling agent; an optional colorant; an optional
`binder; and coated magnetic nanoparticles comprising a mag
`netic metal core and a protective coating disposed on the
`10
`magnetic metal core, the coated magnetic nanoparticles being
`dispersed in the solvent carrier and wherein the protective
`coating comprises a protective material selected from the
`group consisting of polymeric materials, inorganic oxides,
`surfactants and mixtures thereof and further wherein the pro
`tective coating has a thickness of from about 0.2 nm to about
`100 nm.
`In yet other embodiments, there is provided a magnetic ink
`comprising: a solvent carrier, an optional dispersant; an
`optional synergist; an optional antioxidant; an optional vis
`cosity controlling agent; an optional colorant; an optional
`binder; and coated magnetic nanoparticles comprising a mag
`netic metal core and a protective coating disposed on the
`magnetic metal core, the coated magnetic nanoparticles being
`dispersed in the solvent carrier and the protective coating is
`selected from the group consisting of polymeric materials,
`inorganic oxides, Surfactants and mixtures thereof, and fur
`ther wherein the ink is used for Magnetic Ink Character Rec
`ognition (MICR) applications.
`
`15
`
`25
`
`30
`
`4
`a few tens of nanometers or less, ignite spontaneously when
`exposed to oxygen in the ambient environment. For example,
`bare iron, cobalt and alloys nanoparticles are a serious fire
`hazard. Thus, the present embodiments provide a safe method
`for preparation of stable inks suitable for applications that
`require the use of magnetic inks. The present embodiments
`provide coated magnetic metal nanoparticles which are pro
`tected from exposure to water and air. These nanoparticles
`have a coating of various materials, such as for example,
`carbon, polymers, inorganic oxides, Surfactants, or mixtures
`thereof, which acts as a barrier to water or air.
`Magnetic inks are required for two main applications: (1)
`Magnetic Ink Character Recognition (MICR) for automated
`check processing and (2) security printing for document
`authentication. The resulting solvent-based ink can be used
`for these applications. Moreover, as mentioned above, Solid
`ink compositions are not normally designed for multiple
`passes across a magnetic reader. Thus, magnetic Solid ink
`print may wear off during the machine-reading process, either
`for MICR or for document authentication procedures. The
`present embodiments provide a magnetic ink that is solvent
`based. More specifically, the ink of the present embodiments
`is made by dispersing coated magnetic metal nanoparticles in
`a solvent-based composition containing a solvent, an optional
`Viscosity controlling agent, an optional dispersant, an
`optional synergist and optional binder. These solvent-based
`inks comprising the coated magnetic nanoparticles are jetted
`as a liquid dispersion onto the print Substrate. Because the ink
`is in a liquid State when applied to the Substrate, such as paper,
`the magnetic inkpenetrates into the Substrate when printed. In
`contrast to conventional Solid inks which sit on top of the
`substrate, the solvent carrier allows the ink of the present
`embodiments to penetrate the Substrate coating and fibers to
`ensure deposition of the ink components. As a result, the inks
`proved robust magnetic prints that can pass the machine
`reading process steps of MICR or document authentication
`procedures, and be overprinted with other ink types. The
`added robustness also removes the need for adding a clear
`protective overcoat layer over the print, which increases the
`amount of ink used and adds to the pile height of the printed
`documents.
`The resulting solvent ink can also be applied using with
`piezoelectric inkjet print heads. Currently only water based
`MICR inkjet ink are commercially available. Water based
`inks require special care of the printhead to prevent evapora
`tion of the ink or deposition of salts within the channel ren
`dering the jetting ineffective. Furthermore high quality print
`ing with aqueous inks generally requires specially treated
`image substrates. In addition, there is generally a concern
`with respect to possible incompatibility when operating both
`organic materials based inks like Solid, solvent or curable
`Solid inks and water-based inks within the same printer.
`Issues like water evaporation due to the proximity to the
`organic heated ink tanks, rust, high humidity sensitivity of the
`organic inks are key problems which may prevent implemen
`tation of the water-based MICR solution. Thus, the present
`embodiments further avoid these issues.
`The present embodiments provide a solvent-based ink
`made from coated metal magnetic nanoparticles dispersed in
`a solvent-based ink base. The process of ink fabrication com
`prise the following key steps: (1) preparation of a solvent
`Solution containing appropriate dispersant and optionally a
`synergist; (2) addition and breaking of solidaggregates of the
`coated nanoparticles (this step can be achieved by various
`processes including ball milling, attrition or high speed
`homogenizer mixing); (3) optional addition of viscosity con
`trolling agents; and (4) filtration of the ink.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a better understanding of the present embodiments,
`reference may be had to the accompanying figures.
`FIG. 1 illustrates a cross-section of a coated magnetic
`nanoparticle according to the present embodiments;
`FIG. 2 illustrates a cross-section of a coated magnetic
`nanoparticle according to an alternative embodiment to FIG.
`1; and
`FIG. 3 illustrates a cross-section of a coated magnetic
`nanoparticle according to an alternative embodiment to FIG.
`1 or FIG 2.
`
`35
`
`40
`
`DETAILED DESCRIPTION
`
`45
`
`50
`
`60
`
`In the following description, it is understood that other
`embodiments may be utilized and structural and operational
`changes may be made without departure from the scope of the
`present embodiments disclosed herein.
`Solvent ink technology broadens printing capability and
`customer base across many markets, and the diversity of
`printing applications will be facilitated by effective integra
`tion of printhead technology, print process and ink materials.
`As discussed above, while current ink options are Successful
`for printing on various Substrates, there is a need a less com
`55
`plicated method to produce magnetic Solvent inks comprising
`magnetic metal nanoparticles which avoids the safety risks
`associated with the nanoparticles. In addition, solvent-based
`magnetic inks provide for enhanced robustness of the prints.
`The present embodiments are directed generally to sol
`Vent-based magnetic Solid inks. In particular, the present
`embodiments provide inks that are made with coated mag
`netic metal nanoparticles dispersed in a solvent ink base. One
`of the inherent properties of uncoated magnetic metal nano
`particles which precludes their use in the fabrication of com
`65
`mercial inks is their pyrophoric nature; uncoated (bare) mag
`netic nanoparticles of a certain size, typically in the order of
`
`Ex.1027 / IPR2022-00117 / Page 4 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`US 8,409,341 B2
`
`5
`
`10
`
`15
`
`25
`
`5
`The inks are suitable for use in various applications,
`including MICR applications. In addition, the printed inks
`may be used for decoration and for security printing purposes,
`even if the resulting inks do not sufficiently exhibit coercivity
`and remanence suitable for use in MICR applications. The ink
`of the present disclosure exhibits stability, dispersion proper
`ties and magnetic properties that are Superior to that of an ink
`including magnetite.
`The coated magnetic nanoparticles 5 are made of a core
`magnetic nanoparticle 15 coated on the Surface with a coating
`material 10 as shown in FIGS. 1-3. The coated magnetic
`nanoparticles can be produced to have different shapes such
`as oval (FIG. 1), cubed (FIG. 2), and spherical (FIG. 3). The
`shapes are not limited to those depicted in these three figures.
`Suitable coating materials may include a variety of materials,
`including for example, polymers, inorganic oxides, Surfac
`tants and mixtures thereof. Polymeric materials may be
`selected from the group consisting of amorphous, crystalline,
`polymers and oligomers with a low molecular weight (for
`example, a Mw of from about 500 to about 5000, polymers
`with a high molecular weight (for example, a Mw of from
`about 5000 to about 1,000,000), homopolymers, copolymers
`made of one or more types of monomers, and the like, and
`mixtures thereof. Inorganic oxides may be selected from the
`group consisting of silica, titanium oxide, iron oxide, Zinc
`oxide, aluminum oxide, and the like, and mixtures thereof.
`Surfactants may be selected from the group consisting of
`anionic, cationic, non-ionic, Zwitterionic Surfactants, and the
`like, and mixtures thereof. The magnetic ink is made by
`dispersing the coated nanoparticles in a solvent ink base. The
`coating present on the Surface of the nanoparticles provides
`air and moisture stability such that the nanoparticles are safe
`to handle. The amount of the different materials used in the
`coatings depends on the densities of the materials used. In
`general embodiments, the polymer may be present in the
`coating in an amount of from about 0.1 to about 50 percent by
`weight of the total weight of the coating, the Surfactant may be
`present in the coating in an amount of from about 0.1 to about
`30 percent by weight of the total weight of the coating, and the
`inorganic oxide may be present in an amount of from about
`0.5 to about 70 percent by weight of the total weight of the
`coating.
`Solvent Carrier Material
`The ink composition includes a carrier material, or a mix
`ture of two or more carrier materials. In the present embodi
`45
`ments, there is provided a liquid inkjet ink composition in
`which the carrier is one or more organic solvents.
`In the present embodiments, the coated magnetic metal
`nanoparticles are dispersed into the solvent ink base. The
`Solvent may be selected from the group consisting ofisopar
`affins like ISOPAR(R) manufactured by the Exxon Corpora
`tion, hexane, toluene, methanol, ethanol, n-propanol, n-bu
`tanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve,
`acetone, methyl ethyl ketone, cyclohexanone, chloroben
`Zene, methyl acetate, n-butyl acetate, dioxane, tetrahydrofu
`ran, methylene chloride and chloroform, and mixtures and
`combinations thereof. Additional commercially available
`hydrocarbon liquids that may be used include, for example,
`the NORPAR series available from Exxon Corporation, the
`SOLTROL series available from the Phillips Petroleum Com
`60
`pany, and the SHELLSOL series available from the Shell Oil
`Company. In embodiments, the solvent is present in the over
`all ink composition in an amount of from about 0.1 to about 99
`percent, or of from about 10 to about 90 percent, or of from
`about 30 to about 90 percent by weight of the total weight of
`the ink, although the specific amount can be outside of these
`ranges.
`
`6
`In embodiments, the ink exhibits a viscosity, typically on
`the order of less than 15 centipoise (cP) or about 2 to 12 cl at
`jetting temperature (jetting temperature ranging from about
`25° C. to about 140° C.
`Coating Materials for Magnetic Metal Nanoparticles
`Various materials may be used for the nanoparticle coating
`materials, for example, polymers, inorganic oxides, Surfac
`tants and mixtures thereof. The coating is disposed on the
`Surface of the magnetic metal nanoparticles and may have a
`layer thickness of from about 0.2 nm to about 100 nm, or from
`about 0.5 nm to about 50 nm, or from about 1 nm to about 20
`.
`Polymers
`Various polymers are suitable for producing protective
`coating layers for the magnetic metal cores in nanoparticles.
`Suitable examples include Poly(methyl methacrylate)
`(PMMA), polystyrene, polyesters, and the like. Additional
`suitable polymer materials include, without limitation, ther
`moplastic resins, homopolymers of styrene or Substituted
`styrenes such as polystyrene, polychloroethylene, and poly
`vinyltoluene; styrene copolymers such as styrene-p-chlo
`rostyrene copolymer, styrene-propylene copolymer, styrene
`vinyltoluene
`copolymer,
`styrene-vinylnaphthalene
`copolymer, styrene-methyl acrylate copolymer, styrene-ethyl
`acrylate copolymer, styrene-butyl acrylate copolymer, Sty
`rene-octyl acrylate copolymer, styrene-methyl methacrylate
`copolymer, styrene-ethyl methacrylate copolymer, styrene
`butyl methacrylate copolymer, styrene-methyl C-chlo
`romethacrylate copolymer, styrene-acrylonitrile copolymer,
`styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl
`ether copolymer, styrene-vinyl methyl ketone copolymer,
`styrene-butadiene copolymer, styrene-isoprene copolymer,
`styrene-acrylonitrile-indene copolymer, styrene-maleic acid
`copolymer, and styrene-maleic acid ester copolymer, polym
`ethyl methacrylate; polybutyl methacrylate; polyvinyl chlo
`ride; polyvinyl acetate; polyethylene; polypropylene; polyes
`ter, polyvinyl butyral; polyacrylic resin; rosin; modified
`rosin; terpene resin; phenolic resin; aliphatic or aliphatic
`hydrocarbon resin; aromatic petroleum resin: chlorinated
`paraffin, paraffin wax, and the like. In embodiments, the
`protective coating comprises a polymer terminated with a
`functional group which is selected from a group of amide,
`amine, carboxylic acid, phosphine oxide, carboxyklic ester,
`alcohol, thiol. Polymers can be homopolymers or copoly
`mers, linear or branched, random and block copolymers. In
`further embodiments, oxygenbarrier polymeric materials are
`particularly suitable coating materials. Examples of oxygen
`barrier polymeric materials include polyvinylidene chloride
`(PVDC), Ethylene Vinyl Alcohol (EVOH), High Density
`Polyethylene (HDPE), NYLON 6 and the like. Suitable oxy
`gen barrier materials are also available from Dow Chemicals
`(SARAN series resins (e.g., SARAN 168 and SARAN519)).
`Copolymers are also Suitable polymeric coating materials.
`For example, a copolymer made of PVDC and methyl acry
`late monomers may be used for coating. This copolymer is
`also available from Dow Chemicals (e.g., SARAN XU
`32019). Other examples include 10L Blend, SARAN XU
`32019.39 Blend and SARAN XU 32019.40 Blend. Addition
`ally, some of the oxygen barrier polymers, particularly
`copolymers of PVDC with other co-monomers, are soluble in
`various solvents at various temperatures as shown in Table 1.
`
`30
`
`35
`
`40
`
`50
`
`55
`
`65
`
`Ex.1027 / IPR2022-00117 / Page 5 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`US 8,409,341 B2
`
`7
`TABLE 1.
`
`8
`dispersion in the presence of a -SH terminated polymer.
`Suitable polymers include, for example PMMA.
`The Surface of magnetic nanoparticles can be modified: by
`grafting; atom transfer radical polymerization (ATRP) and
`reversible addition-fragmentation chain transfer (RAFT)
`polymerization techniques (the latter using a chain transfer
`agent but no metal catalyst); Solvent evaporation method;
`layer by layer process; phase separation method; sol-gel tran
`sition; precipitation technique; heterogeneous polymeriza
`tion in the presence of magnetic particles; Suspension/emul
`sion polymerization; microemulsion polymerization; and
`dispersion polymerization.
`In addition to the known methods described above, a num
`ber of specific techniques are of interest, such as for example,
`use of Sonochemistry for chemical grafting of anti-oxidant
`molecules with additional hydrophobic polymer coating
`directly onto TiO, particle surfaces (Chem. Commun., 4815
`4817 (2007)); use of pulse-plasma techniques (J. of Macro
`molecular Science, Part B: Physics, 45: 899-909 (2006)); use
`of Supercritical fluids and anti-solvent process for coating/
`encapsulation of microparticles with a polymer (J. of Super
`critical Fluids, 28: 85-890 (2004)); and use of electrohydro
`dynamic atomization for the production of narrow-size
`distribution polymer-pigment-nanoparticle composites.
`Encapsulation/coating and Surface modifications of nano
`particles, and particularly magnetic nanoparticles with poly
`mers, also provide useful methods that can be used to fabri
`cate the ink of the present embodiments. For example,
`polymer-coated iron nanoparticles may beformed by thermal
`decomposition of iron pentacarbonyl in a solvent in the pres
`ence of a modified polymer structure with a terminal anchor
`ing group, tetraethylenepentaamine (TEPA) (Burke et al.,
`Chemical Materials, 14: 4752-61 (2002)). After filtration and
`Solvent removal, the core-shell iron nanoparticles contain a
`shell made out of the polymeric material, for example, poly
`isobutylene (PIB), polystyrene (PS), and polyethylene (PE).
`Polystyrene coated nanoparticles may be obtained by thermal
`decomposition of iron carbonyl gas in the presence of styrene
`monomer by using plasma polymerization techniques (Sri
`kanthet al., Applied Physics Letters, 79:3503-5 (2001)). The
`plasma generated heat initiates fast decomposition of the iron
`carbonyl while at the same time the styrene breaks down
`forming free radicals which initiate the polymerization pro
`cess on the Surface of the generated iron nanoparticles.
`All of the above literature are hereby incorporated by ref
`erence in their entirety as disclosing methods for providing
`polymer coated magnetic nanoparticles.
`Inorganic Oxides
`Suitable inorganic oxides for use as coating materials
`include silica, titania, iron oxide, aluminum oxide, Zinc oxide
`and other similar inorganic oxides and mixtures thereof.
`Generally, the process of ink fabrication comprise a few
`main steps: (1) prepare a solvent solution containing an
`appropriate dispersant and optionally a synergist; (2) addition
`and breaking of Solid aggregates of inorganic oxide-coated
`nanoparticles, which can be achieved by various processes,
`including but not limited to, ball milling, attrition or high
`speed homogenizer mixing; (3) optionally adding viscosity
`controlling agents; and (4) filtration of the ink. Methods for
`fabrication of the inorganic oxide coated nanoparticles and
`particularly suitable for magnetic nanoparticle coating are
`known and some representative examples described below.
`Methods for fabrication of such core-shell particles having
`a protective layer (shell) made out of inorganic oxide are
`described in, for example, U.S. Patent Publication No. 2010/
`0304006, which describes a method wherein the silica coat
`ing on the Surface of metal nanoparticles is provided by
`
`Polymer Material
`PVDC homopolymer
`PVDC homopolymer
`PVDC homopolymer
`PVDC copolymers
`PVDC copolymers
`PVDC copolymers
`
`Solvent
`N-methylpyrrollidine
`tetramethylene sufloxide
`N-acetylpiperidine
`tetrahydrofuran
`1,4-dioxane
`cyclohexanone
`
`Temperature at
`which polymer
`dissolves (C.)
`42
`28
`34
`<60
`SO-100
`SO-100
`
`10
`
`15
`
`25
`
`The polymer coating on magnetic nanoparticles provides
`stability against air and moisture but also increases compat
`ibility of the magnetic particles with the ink base due to the
`fact that both the polymer coating and the ink base are organic
`materials. Thus, this compatibility results in good dispersibil
`ity of the magnetic nanoparticles as compared to bare mag
`netic metal nanoparticles. As a result, there may be situations
`when, depending on the actual ink base components and the
`type of polymer, a synergist or dispersant may not be required
`at all or the amount needed is significantly decreased, thus
`saving extra components and costs.
`Generally, the process of ink fabrication comprise a few
`main steps: (1) prepare a solvent solution containing an
`appropriate dispersant and optionally a synergist; (2) addition
`and breaking of solid aggregates of polymer-coated nanopar
`ticles, which can be achieved by various processes, including
`but not limited to, ball milling, attrition or high speed homog
`enizer mixing; (3) optionally adding Viscosity controlling
`30
`agents; and (4) filtration of the ink. Methods for fabrication of
`the polymer coated nanoparticles and particularly suitable for
`magnetic nanoparticle coating are known and some represen
`tative examples described below.
`Coatings and methods for coating particles with polymers
`layers are described in, for example, Caruso. F., Advanced
`Materials, 13: 11-22 (2001). Polymer coated nanoparticles
`can be obtained via synthetic and non synthetic routes: poly
`merization of the particle Surface; adsorption onto the par
`ticles; Surface modifications via polymerization processes;
`self-assembled polymer layers; inorganic and composite
`coatings including precipitation and Surface reactions and
`controlled deposition of preformed inorganic colloids; and
`use of biomacromolecular layer in specific applications. A
`number of techniques for the preparation of magnetic nano
`45
`and micronized particles are also described in Journal of
`Separation Science, 30: 1751-1772 (2007). Polystyrene
`coated cobalt nanoparticles are described in U.S. Publication
`No. 2010/0015472 to Bradshaw, which is hereby incorpo
`rated by reference. The disclosed process consists of thermal
`decomposition of dicobalt octacarbonyl in dichlorobenzene
`as a solvent in the presence of a polystyrene polymer termi
`nated with a phosphine oxide group and an amine terminated
`polystyrene, at 160° C. under argon. The process provided
`magnetic cobalt nanoparticles having a polymer coating
`including a polystyrene shell. Additionally, other polymer
`shells can be placed on the surface of the coated cobalt nano
`particles by exchange of the original polystyrene shell with
`other polymers. The reference further describes replacement
`of the polystyrene shell on coated nanoparticles by polym
`ethylmethacrylate shell, through exchange reaction with
`polymethyl methacrylate (PMMA) in toluene. These poly
`mer coated magnetic nanoparticle materials are also suitable
`for fabrication of magnetic inks. U.S. Publication No. 2007/
`0249747 to Tsuji et al. discloses fabrication of polymer
`coated metal nanoparticles from magnetic FePt nanoparticles
`of a particle size of about 4 nm by stirring FePt nanoparticle
`
`35
`
`40
`
`50
`
`55
`
`60
`
`65
`
`Ex.1027 / IPR2022-00117 / Page 6 of 13
`APPLE INC. v. SCRAMOGE TECHNOLOGY, LTD.
`
`

`

`US 8,409,341