Passivation of iron particles

Abstract

To provide coated iron particles hard to be corroded, and also maintaining its magnetic properties even after passivation, a composition, and a coating method therefor.SOLUTION: Provided is a method for passivating iron particles comprising: a step where a passivation agent including one or more sulfur parts is introduced into a solvent to form a passivation liquid; and a step where the iron particles are contacted with a passivation solution to form coated iron particles.SELECTED DRAWING: None

Description

[Technical field]

[0001] Aspects of the invention provide thiol-coated iron particles, compositions including thiol-coated iron particles, components having the compositions deposited thereon, and methods for passivating iron particles. [Background technology]

[0002] In recent years, magnetic particles, especially iron particles, have attracted much attention and are widely used due to their excellent magnetic properties. They can be applied in various fields of technology, biomedical applications, absorption and catalytic processes, or for producing magnetorheological fluids and composites. Depending on the desired size, the iron particles can be nano-, micro- or macroscopic in size.

[0003] For example, carbonyl iron particles are the main component for the design of magnetic electromagnetic wave absorbers. Carbonyl iron consists of iron-containing carbonyl moieties (e.g. Fe(CO) 5 Carbonyl iron powder (CIP) is a substantially pure iron (iron content of 99.9% or more) formed from carbonyl iron powder (CIP), which has unique magnetic properties that make it useful in many applications and is a desirable additive for coatings due to its magnetic properties. However, carbonyl iron is susceptible to oxidation and corrosion at high temperatures, which leads to a decrease in its magnetic properties. In addition, CIP is difficult to disperse uniformly and failure to disperse properly can affect CIP performance. For example, methods such as coating particles with polymers can cause particle agglomeration, which prevents the particles from dispersing.

[0004] For example, silicate iron has been used instead of carbonyl iron because it is relatively less susceptible to corrosion and easier to process. Known passivation techniques for carbonyl iron or silicate iron include: carbon dioxide passivation, electroless plating of cobalt, polyaniline passivation, microwave plasma, and silica coating. These methods involve multiple / complex processing steps that can result in a substantial increase in the mass and volume of the particles, leading to agglomeration of the resulting particles and potentially compromising their magnetic properties.

[0005] There is a need for passivated iron particles while retaining or improving their magnetic properties, and for improved methods for passivating iron particles. Summary of the Invention

[0006] The present invention provides coated iron particles, or reaction products thereof, comprising iron particles and a thiol coating deposited on the iron particles.

[0007] Aspects of the invention further provide compositions comprising coated iron particles and a polymer or adhesion promoter.

[0008] A further aspect of the invention provides a component, such as a vehicle component, having a surface and a composition of the invention attached to the surface.

[0009] Aspects of the invention further provide a method for passivating iron particles by introducing a passivation agent having one or more sulfur moieties into a solvent to form a passivation solution; and contacting the iron particles with the passivation solution to form coated iron particles.

[0010] Aspects of the invention further provide a method for passivating iron particles by introducing iron particles into a solvent to form an iron particle solution; and contacting a passivation agent having one or more sulfur moieties with the iron particle solution to form coated iron particles. [Brief description of the drawings]

[0011] In order that the above-mentioned features of the present invention may be understood in detail, a more detailed description of the above summary will be made with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that since the present invention admits of other equally effective embodiments, the accompanying drawings illustrate only typical embodiments of the invention and are therefore not intended to limit the scope of the present disclosure.

[0012] [Figure 1] SUMMARY OF THE DISCLOSURE An aircraft having a vehicle component in accordance with at least one embodiment of the present invention. [Diagram 2] FIG. 1 is a flow diagram of a method for forming thiol-coated iron particles in accordance with at least one embodiment of the present invention. [Figure 3A] 1 is a scanning electron microscope image of carbonyl iron particles that have not undergone thiol passivation, in accordance with at least one embodiment of the present invention. [Figure 3B] 1 is a scanning electron microscope image of carbonyl iron particles that have not undergone thiol passivation, in accordance with at least one embodiment of the present invention. [Figure 3C] 1 is a scanning electron microscope image of carbonyl iron particles that have not undergone thiol passivation, in accordance with at least one embodiment of the present invention. [Figure 4A] 1 is a scanning electron microscope image of carbonyl iron particles passivated with 2,5-dimercapto-1,3,4-thiadiazole, in accordance with at least one embodiment of the present invention. [Figure 4B] 1 is a scanning electron microscope image of carbonyl iron particles passivated with 2,5-dimercapto-1,3,4-thiadiazole, in accordance with at least one embodiment of the present invention. [Figure 4C] 1 is a scanning electron microscope image of carbonyl iron particles passivated with 2,5-dimercapto-1,3,4-thiadiazole, in accordance with at least one embodiment of the present invention. [Figure 5A]FIG. 4 is an energy dispersive spectroscopy spectrum of an SEM image of the carbonyl iron particles of FIGS. 3A-3C, in accordance with at least one embodiment of the present invention. [Figure 5B] 4A-4C are energy dispersive spectroscopy spectra of SEM images of iron particles passivated with 2,5-dimercapto-1,3,4-thiadiazole, in accordance with at least one embodiment of the present invention. [Figure 6] A is a photograph of a panel coated with a polyurethane coating with unmodified carbonyl iron particles, and B is a photograph of a panel coated with a polyurethane coating with thiol-coated iron particles.

[0013] To facilitate understanding, the same reference numbers have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention relates to coated iron particles and compositions that provide iron particles that are resistant to corrosion and that maintain their magnetic properties after passivation. The method of forming the coated iron particles of the present invention provides a simple (e.g., three-step) process that uses relatively inexpensive materials, all of which reduces manufacturing time and costs compared to conventional iron coating methods.

[0015] Coated iron particles The present invention provides iron particles having a thiol coating. The thiol coating can partially or completely coat the outer surface of the iron particles. The iron particles can be substantially pure iron. The iron particles can include carbonyl iron particles or silica iron particles. In at least one embodiment, the coated iron particles have a diameter of about 0.5 microns to about 1000 microns, such as about 1 micron to about 100 microns, such as about 1 micron to about 20 microns, such as about 1 micron to about 5 microns, such as about 1 micron to about 3 microns, such as about 1.2 microns. It has been found that large particles (e.g., larger than 1000 microns) are difficult to disperse and spray coat uniformly due to their weight. Smaller particles are easier to disperse and spray coat uniformly. The iron particles of the present invention can have an iron content of about 90 wt% or more, such as about 95 wt% or more, such as about 99 wt% or more, such as about 99.9 wt% or more. Iron particles can be obtained from commercial sources such as BASF (Ludwigshafen, Germany).

[0016] In at least one embodiment, a thiol coating is deposited on the iron particles, the coating having a thickness of about 30 Angstroms to about 15,000 Angstroms, e.g., about 100 Angstroms to about 1,000 Angstroms. In at least one embodiment, the coated iron particles have a thiol coating content of about 0.01 volume percent (vol%) to about 30 vol%, e.g., about 0.05 vol% to about 10 vol%, e.g., about 0.1 vol% to about 1 vol%, e.g., about 0.5 vol%, based on the total volume of the thiol-coated iron particles, as determined by the difference in weight and density of the particles before and after coating the particles. In at least one embodiment, the coated iron particles have a thiol coating content of about 0.5 weight percent (wt%) to about 30 wt%, e.g., about 1 wt% to about 10 wt%, e.g., about 2 wt% to about 5 wt%, e.g., about 3 wt%, based on the total weight of the thiol-coated iron particles, as determined by the difference in weight of the particles before and after coating the particles. As used herein, the "thiol coating content" of the iron particles is the percentage of the volume or weight of the coated iron particles that is thiol-coated.

[0017] The thiol coating of the present invention has no or negligible effect on the magnetic susceptibility of the iron particles. In electromagnetism, magnetic susceptibility (Latin: susceptibilis, "receptive"; χ s The susceptibility, denoted by χ, is a measure of one of the magnetic properties of a material. The susceptibility indicates whether a material is attracted to or repelled by a magnetic field, and thus may have implications for practical applications. As the volume of the particle increases (for pure iron), the χ s In the coating, as the volume fraction increases, χ s Therefore, in the core-shell case (where the core is iron and the shell is a passivation layer), χ s will decrease as the shell becomes thicker. Also, as the particle erodes, the core size decreases, and χ sThe thiol coating of the present invention prevents or inhibits corrosion of iron particles.

[0018] In at least one embodiment, the coated iron particles of the present invention have a diameter of about 1 micron to about 5 microns and a particle size of about 3×. s About 10x from s In at least one embodiment, the coated iron particles of the present invention have a χ of about 0.5:1 to about 1.5:1, such as about 0.7:1 to about 1.2:1, e.g., about 1:1. s and the particle diameter. s The ratio of the particle diameter to the surface area indicates that the thiol coating of the present invention has no or negligible effect on the magnetic susceptibility of the iron particles, thereby maintaining the dispersibility of the coated particles. The coated iron particles and compositions of the present invention, unlike conventional coated iron particles, such as silica-coated iron particles, are uniformly well dispersed (e.g., do not agglomerate) compared to unpassivated iron particles.

[0019] The thiol coating provides corrosion resistance to the iron particles in addition to facilitating dispersion of the coated particles when in a composition containing other iron particles, e.g., other coated iron particles. Furthermore, the thiol coating of the present invention is thick enough to adequately protect the iron particles from corrosion, but thin enough that the magnetic properties of the iron particles are not substantially reduced. The thiol coating of the present invention can be a self-assembled passivation monolayer on the iron particle surface. Without being bound by theory, the thiol compound(s) of the thiol coating can be covalently bonded to the iron particle surface.

[0020] The thiol coating of the present invention comprises and / or is the reaction product of one or more thiol compounds. In at least one embodiment, the thiol compounds are selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols.

[0021] The thiol compound of the present invention can be an organic compound containing disulfide and / or thiolate groups (e.g., metal-sulfide bonds). The thiol compound can be an alkyl polythiol, such as a dithiol, trithiol, or tetrathiol. Compared to monothiols, polythiols can provide additional thiol moieties that can interactively bond / covalently bond to iron particles, resulting in a thiol coating attached to the iron particles with reduced thickness, increased overall bond strength to the iron particles, and maintained / improved magnetic properties of the coated iron particles. Dithiols can include ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, hexanedithiol, pentanedithiol, octanedithiol, nonanedithiol, and decanedithiol. The trithiols can include ethane trithiol, propane trithiol, butane trithiol, pentane trithiol, hexane trithiol, pentane trithiol, octane trithiol, nonane trithiol, and decane trithiol. The tetrathiols can include ethane tetrathiol, propane tetrathiol, butane tetrathiol, pentane tetrathiol, hexane tetrathiol, pentane tetrathiol, octane tetrathiol, nonane tetrathiol, and decane tetrathiol.

[0022] In at least one embodiment, the thiol compound has the formula: 1 --S n --X--R 2 (In the formula, R 1 is an organic group, n is an integer of 1 or more, X is a sulfur or metal atom, and R 2 R is an organic group. 1 and R 2 In at least one embodiment, one or both of the thiol compounds may include additional polysulfide groups and / or thiol groups. Further, in at least one embodiment, the thiol compound may be represented by the formula -(R 1 --S n --X--R 2 ) q -(In the formula, R 1is an organic group, n is a positive integer, X is a sulfur or metal atom, R 2 is an organic group and q is a positive integer. In at least one embodiment, R (of the polymeric or monomeric corrosion inhibitor) 1 and R 2 is independently selected from H, alkyl, cycloalkyl, aryl, thiol, polysulfide, or thione. 1 and R 2 Each of R may be independently substituted with a moiety selected from alkyl, amino (phosphorus-containing), ether, alkoxy, hydroxy (sulfur-containing), selenium, or tellurium. 1 and R 2 Each of R has 1 to 24 carbon and / or non-hydrogen atoms. For example, R 1 and R 2 Examples of heterocyclic rings of groups include azoles, triazoles, thiazoles, dithiazoles and / or thiadiazoles.

[0023] In at least one embodiment, the thiol compound comprises a metal in a metal-thiolate complex. The thiol compound may comprise a metal center and one or more thiol groups (ligands) bonded and / or coordinated to the metal center with a metal-sulfide bond. Thiolates are derivatives of thiols in which a metal atom replaces the hydrogen bonded to the sulfur. Thiolates can be represented by the general formula MSR 1 (wherein M is a metal and R 1 R is an organic group. 1 can contain a disulfide group. Metal-thiolate complexes can be represented by the general formula M-(SR 1 ) n where n is generally an integer from 2 to 9, and M is a metal atom. The metal is copper, zinc, zirconium, aluminum, iron, cadmium, lead, mercury, silver, platinum, palladium, gold, and / or cobalt.

[0024] In at least one embodiment, the thiol compound comprises an azole. Examples of suitable azoles include cyclic compounds with one nitrogen atom, such as pyrrole, two or more nitrogen atoms, such as pyrazole, imidazole, triazole, tetrazole and pentazole, one nitrogen atom and one oxygen atom, such as oxazole and isoxazole, and one nitrogen atom and one sulfur atom, such as thiazole and isothiazole. Non-limiting examples of suitable azole-containing thiol compounds include 2,5-dimercapto-1,3,4-thiadiazole, 1H-benzotriazole, 1H-1,2,3-triazole, 2-amino-5-mercapto-1,3,4-thiadiazole, also known as 5-amino-1,3,4-thiadiazole-2-thiol, 2-amino-1,3,4-thiadiazole. In at least one embodiment, for example, the azole can be 2,5-dimercapto-1,3,4-thiadiazole. In some embodiments, the azole-containing thiol compound comprises benzotriazole and / or 2,5-dimercapto-1,3,4-thiadiazole.

[0025] The thiol compounds of the present invention include heterocyclic thiols and amines that can provide elimination of oxygen reduction. Heterocyclic thiols include thiadiazoles having one or more thiol moieties. Non-limiting examples of thiadiazoles having one or more thiol moieties include those represented by formula (I) or formula (II): This includes 1,3,4-thiadiazole-2,5-dithiol and thiadiazole represented by TIFF0007658710000001.tif30170.

[0026] The thiadiazole of formula (I) can be purchased from Vanderbilt Chemicals, LLC, Norwalk, Connecticut, and is known as Vanlube® 829. The thiadiazole of formula (II) can be purchased from WPC Technologies, Inc. TM (Oak Creek, Wisconsin) and InhibiCor TM It is known as the 1000.

[0027] The thiol compounds of the present invention include selected derivatives of trithiocyanuric acid ("TMT"), which may be used as corrosion inhibitors in conjunction with paints, and HS-CN. 2 It may be a derivative of 2,5-dimercapto-1,3,4 thiadiazole, represented by SC-SH or "DMTD". Examples include 2,5-dimercapto-1,3,4 thiadiazole (DMTD) and 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole, and trithiocyanuric acid (TMT). Other examples include N-, S- and N,N-, S,S- and N,S-substituted derivatives of DMTD, such as 5-mercapto-3-phenyl-1,3,4-thiadiazoline-2-thione or bismuthiol II (3-phenyl-1,3,4-thiadiazolidine-2,5-dithione), and various S-substituted derivatives of trithiocyanuric acid. Other examples include 5,5'dithio-bis(1,3,4 thiadiazole-2(3H)-thione or (DMTD) 2 or a polymer of DMTD (DMTD); 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione); or a dimer and polymer of TMT (TMT) 2 Other examples include the general formula: M(DMTD) n (Wherein, n=1, 2 or 3, and M is a metal cation such as M=Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I, Sb(III), Sn(II), Fe(II) or Cu(II) (e.g., ZnDMTD, Zn(DMTD) 2 , Bi(DMTD) 3 )) salts of DMTD; analogous salts of TMT in a 1:1 ratio, such as ZnTMT; and similarly soluble Li(I), Ca(II), Sr(II), Mg(II), La(III), Ce(III), Pr(III) or Zr(IV) salts. Additional examples include salts of the general formula M[(DMTD) n ] m(DMTD) where n=2 or n>2, m=1, 2 or 3, and M is a metal cation, e.g., M=Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I), Sb(III), Sn(II), Fe(II) or Cu(II). n A typical example is Zn[(DMTD) 2 ], Zn[(DMTD) 2 ] 2 It is.

[0028] Additional examples include DMTD, (DMTD) n or ammonium-, aryl- or alkyl-ammonium salts of 5,5'thio-bis(1,3,4 thiadiazole-2(3H)-thione or 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole. Typical examples include cyclohexylamine:DMTD in ratios of 1:1 and 2:1; di-cyclohexylamine:DMTD in ratios of 1:1 and 2:1; aniline:DMTD in ratios of 1:1 and 2:1; analogous salts of TMT (e.g. di-cyclohexylamine:TMT) in a ratio of 1:1. Further examples include DMTD or (DMTD) formed with polyamines. n and polyammonium salts of TMT.

[0029] Further examples include DMTD or (DMTD) 2 or 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione and intrinsically conductive polyaniline doped with TMT; DMTD, (DMTD) 2 and intrinsically conductive polypyrroles and / or polythiophenes doped with 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione and / or TMT.

[0030] Further examples include polyDMTD / polyaniline, polyDMTD / polypyrrole and polyDMTD / polythiophene micro- or nanocomposites; similar micro- or nanocomposites with TMT and with 5,5'thio-bis(1,3,4 thiadiazole-2(3H)-thione; DMTD or salts of DMTD or derivatives of DMTD and TMT as organic components of various pigment grade inorganic matrices or physical mixtures. In some embodiments, such inorganic matrices contain anionic and cationic species with corrosion inhibitor properties, such as MoO 4 - , P.O. 4 - , H.P.O. 3 - , Poly-phosphate, BO 2 - , SiO 4 - , N.C.N. - , WO 4 - , phosphomolybdate, and phosphotungstate, respectively, containing Mg, Ca, Sr, La, Ce, Zn, Fe, Al, and Bi.

[0031] DMTD in pigment grade form is Zn(DMTD) with inorganic products or corrosion inhibitor pigments 2 and Zn-DMTD (among other organic and inorganic salts of the former), including phosphates, molybdates, borates, silicates, tungstates, phosphotungstates, phosphomolybdates, cyanamides or carbonates, and oxides of the aforementioned cationic species. Examples include zinc phosphate, cerium molybdate, calcium silicate, strontium borate, zinc cyanamide, cerium phosphotungstate, ZnO, CeO 2 , ZrO 2 , and amorphous SiO 2 Includes:

[0032] Compositions and Coated Components The thiol-coated iron particles of the present invention may be present in a composition. In at least one embodiment, the composition of the present invention includes thiol-coated iron particles and one or more polymers or adhesion promoters. In at least one embodiment, the polymer includes at least one of a thermosetting polymer or a thermoplastic polymer. In at least one embodiment, the polymer is at least one of an epoxy, a bismaleimide, a polyimide, a polyaryletherketone (e.g., a polyetheretherketone or a polyetherketone), a sol-gel, a polyurethane, a sealant, or a magnetorheological particle fluid. The adhesion promoter can be a sol-gel. The sol-gel can be Boegel®, e.g., 3M Surface Pre-Treatment AC-131 CB. A 3% AC-131 kit can be obtained from 3M Corporation. 3% AC-131 is a non-chrome conversion coating that typically adheres on aluminum, nickel, stainless steel, magnesium, and titanium alloys. AC-131 has Part A, which is an aqueous mixture of glacial acetic acid (GAA) and zirconium tetra-n-propoxide (TPOZ), and Part B, which is (3-glycidyloxypropyl)trimethoxysilane (GTMS). These two components are mixed together (Part A+Part B), and the molar ratio of silicon to zirconium in the mixture is 2.77:1. The molar ratio of acetic acid to TPOZ in Part A is 0.45:1. Measured volumes of GAA and TPOZ can be mixed vigorously for about 10 minutes and then added to Part A from the AC-131 kit. The premixed Part A solution can then be added to a measured volume of Part B solution from the AC-131 kit with stirring, followed by a 30 minute induction period. The coated iron particles of the present invention can be added to the Part A / Part B mixture before, during, or after the incubation period. The composition can then be deposited on a surface of a component, such as on a surface of a vehicle component.

[0033] Sealant materials include silicones, polyurethanes and epoxies.

[0034] Magnetorheological particulate fluids include particles dispersed in hydrocarbon oils, silicone oils, water phosphate ester fluids, and synthetic oils.

[0035] Synthetic oils include the following groups:Group I: conventional non-synthetic oils. Made from fractionated petroleum that has been refined to improve certain performance categories such as wax content and oxidation resistance;Group II: conventional, non-synthetic oils. Made from fractionated petroleum that has been further refined by hydrocracking (hydrogen-based processing);Group III: synthetic oils considered, but with some important similarities to conventional oils. Similar to Group II, but with a higher viscosity index due to further hydrocracking refinement;Group IV: synthetic oils. Includes polyalphaolefins (PAOs);Group V: This separate group describes any material that does not fit into any of the above four groups.

[0036] The compositions of the present invention may have a coated iron particle content of about 0.1 wt% to about 50 wt%, such as about 0.5 wt% to about 10 wt%, such as about 1 wt% to about 5 wt%, such as about 2 wt%. As used herein, the "iron particle content" of a composition is the percentage by weight of the composition that includes the coated iron particles.

[0037] The compositions of the present invention can be deposited onto a surface, such as the surface of a vehicle component. When deposited onto a component, such as a vehicle component, the compositions of the present invention provide a magnetic radar absorber capable of absorbing incoming radio wave radiation at frequencies from about 30 MHz to about 300 Gz, such as from about 300 MHz to about 30 GHz, such as from about 3,000 MHz to about 3 GHz.

[0038] The compositions of the present invention may also be deposited on one or more surfaces of a wind turbine, satellite, or other vehicle, such as a car, boat, or the like.

[0039] Depositing the composition on the surface can be performed by spraying, dipping, brushing, and / or wiping to form a layer of the composition. For example, suitable forms of spraying include spraying with a spray gun, a high volume low pressure spray gun, and / or a hand pump sprayer. The solution is then cured (at room temperature or elevated temperature). In at least one embodiment, the curing temperature is from about 10° C. to about 150° C., such as from about 20° C. to about 100° C., such as from about 30° C. to about 70° C., such as from about 40° C. to about 50° C. Curing can be performed for a period of from about 15 minutes to about 72 hours. A layer of the cured composition of the present invention can have a thickness of from about 0.5 mm to about 500 mm, such as from about 5 mm to about 100 mm, such as from about 10 mm to about 50 mm.

[0040] A vehicle component is a structural component of a vehicle, such as an aircraft landing gear, a panel, a joint, etc. Examples of vehicle components include an airfoil (e.g., a rotor blade), an auxiliary power unit, an aircraft nose, a fuel tank, a tail cone, a panel, a coated lap joint between two or more panels, a wing-fuselage assembly, a structural aircraft composite, a fuselage body-joint, a wing rib-to-skin joint, and / or other internal components.

[0041] Figure 1 is an aircraft with vehicle components according to at least one embodiment of the present invention. As shown in Figure 1, the aircraft 100 includes an aircraft structure 102 including vehicle components such as an elongated fuselage 104, wings 106 extending laterally from the fuselage 104, and a tail section 108 extending longitudinally from the fuselage 104. The composition of the present invention may be deposited onto one or more surfaces of such aircraft components to form one or more aircraft component(s) having the composition adhered thereto.

[0042] Other possible end uses of the coated iron particles and / or compositions of the invention may include incorporating the coated iron particles and / or compositions into magnetic tapes (e.g., storage media), motors (e.g., magnetic bearings), wind turbines (e.g., Doppler radar absorbers that absorb electromagnetic radiation), shielding for nuclear magnetic resonance spectroscopy (NMR) (e.g., magnetic coatings), lining anechoic chambers (as foam absorbers), mu metals to effect changes in magnetic field strength, and in or on protecting computer chips from frequency exposure as "RF blankets". The methods of the invention may also include passivating copper particles (e.g., any small particles of metal that are prone to corrosion) for use in products such as conductive inks.

[0043] Passivation of iron particles The present invention provides a method for forming thiol-coated iron particles by passivating the iron particles with a passivation agent. Figure 2 illustrates a method 200 for forming thiol-coated iron particles. The method 200 includes forming a passivation solution by dissolving or dispersing a passivation agent having one or more sulfur moieties in a solvent (Block 202).

[0044] The solvent may be aqueous or non-aqueous (e.g., organic). Preferably, the solvent is non-aqueous and contains little or no ammonium hydroxide. It has been found that non-aqueous solvents prevent iron particles from caking when present in the passivation solution. In at least one embodiment, the organic solvent is selected from alcohol, alkyl carbonate (e.g., dimethyl carbonate, diethyl carbonate, or dipropyl carbonate), ether (e.g., dimethyl ether or dipropylene glycol dimethyl ether), glycol ether, tetrahydrofuran (THF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), or mixtures thereof. In at least one embodiment, the alcohol solvent is one or more of ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and amyl alcohol (e.g., n-pentanol, isopentanol, and sec-pentanol). Non-aqueous solvents can be degassed to remove air and moisture from the solvent by (1) introducing 3 Å or 4 Å molecular sieves into the solvent and heating the solvent, and / or (2) bubbling an inert gas (such as nitrogen or argon) through the solvent for a period of from about 10 minutes to about 24 hours.

[0045] In at least one embodiment, the concentration of the passivation agent (moles per liter) in the passivation solution is from about 0.01 moles / liter (M) to about 10M, such as from about 0.5M to about 5M, such as from about 1M to about 2M.

[0046] In at least one embodiment, the passivation agent is a thiol compound. In at least one embodiment, the passivation agent is selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols.

[0047] The thiol compound of the present invention can be an organic compound containing a disulfide group and / or a thiolate group (e.g., a metal-sulfide bond). The thiol compound is an alkyl polythiol, such as a dithiol, trithiol, or tetrathiol. The dithiol can include ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, hexanedithiol, pentanedithiol, octanedithiol, nonanedithiol, and decanedithiol. The trithiol can include ethanetrithiol, propanetrithiol, butanedithiol, pentanetrithiol, hexanetrithiol, pentanetrithiol, octanetrithiol, nonanedithiol, and decanetrithiol. The tetrathiols can include ethane tetrathiol, propane tetrathiol, butane tetrathiol, pentane tetrathiol, hexane tetrathiol, pentane tetrathiol, octane tetrathiol, nonane tetrathiol, and decane tetrathiol.

[0048] In at least one embodiment, the thiol compound has the formula: 1 --S n --X--R 2 (In the formula, R 1 is an organic group, n is an integer of 1 or more, X is a sulfur or metal atom, and R 2 R is an organic group. 1 and R 2 In at least one embodiment, one or both of the thiol compounds may include additional polysulfide groups and / or thiol groups. Further, in at least one embodiment, the thiol compound may be represented by the formula -(R 1 --S n --X--R 2 ) q -(In the formula, R 1 is an organic group, n is a positive integer, X is a sulfur or metal atom, R 2 is an organic group and q is a positive integer. In at least one embodiment, R (of the polymeric or monomeric corrosion inhibitor) 1 and R 2is independently selected from H, alkyl, cycloalkyl, aryl, thiol, polysulfide, or thione. 1 and R 2 Each of R1 and R2 may be independently substituted with a moiety selected from alkyl, amino, phosphorus-containing, ether, alkoxy, hydroxy, sulfur-containing, selenium, or tellurium. In at least one embodiment, R1 and R2 each have 1 to 24 carbon and / or non-hydrogen atoms. For example, R 1 and R 2 Examples of heterocyclic rings of groups include azoles, triazoles, thiazoles, dithiazoles and / or thiadiazoles.

[0049] In at least one embodiment, the thiol compound comprises a metal in a metal-thiolate complex. The thiol compound may comprise a metal center and one or more thiol groups (ligands) bonded and / or coordinated to the metal center with a metal-sulfide bond. Thiolates are derivatives of thiols in which a metal atom replaces the hydrogen bonded to the sulfur. Thiolates can be represented by the general formula MSR 1 (wherein M is a metal and R 1 R is an organic group. 1 can contain a disulfide group. Metal-thiolate complexes can be represented by the general formula M-(SR 1 ) n where n is generally an integer from 2 to 9, and M is a metal atom. The metal is copper, zinc, zirconium, aluminum, iron, cadmium, lead, mercury, silver, platinum, palladium, gold, and / or cobalt.

[0050] In at least one embodiment, the thiol compound comprises an azole. Examples of suitable azoles include cyclic compounds having one nitrogen atom, such as pyrrole, two or more nitrogen atoms, such as pyrazole, imidazole, triazole, tetrazole and pentazole, one nitrogen atom and one oxygen atom, such as oxazole and isoxazole, and one nitrogen atom and one sulfur atom, such as thiazole and isothiazole. Non-limiting examples of suitable azole-containing thiol compounds include 2,5-dimercapto-1,3,4-thiadiazole, 1H-benzotriazole, 1H-1,2,3-triazole, 2-amino-5-mercapto-1,3,4-thiadiazole, also known as 5-amino-1,3,4-thiadiazole-2-thiol, 2-amino-1,3,4-thiadiazole. In at least one embodiment, for example, the azole is 2,5-dimercapto-1,3,4-thiadiazole. In some embodiments, the azole-containing thiol compound comprises benzotriazole and / or 2,5-dimercapto-1,3,4-thiadiazole.

[0051] The thiol compounds of the present invention include heterocyclic thiols and amines that can provide elimination of oxygen reduction. Heterocyclic thiols include thiadiazoles having one or more thiol moieties. Non-limiting examples of thiadiazoles having one or more thiol moieties include those represented by formula (I) or formula (II): This includes 1,3,4-thiadiazole-2,5-dithiol and thiadiazole represented by TIFF0007658710000002.tif31170.

[0052] Thiadiazoles of formula (I) can be purchased from Vanderbilt Chemicals, LLC, Norwalk, Connecticut, and are known as Vanlube® 829. Thiadiazoles of formula (II) can be purchased from WPC Technologies, Inc. TM (Oak Creek, Wisconsin) and InhibiCor TM It is known as the 1000.

[0053] The thiol compounds of the present invention include selected derivatives of trithiocyanuric acid ("TMT"), which may be used as corrosion inhibitors in conjunction with paints, and HS-CN. 2 It may be a derivative of 2,5-dimercapto-1,3,4 thiadiazole, represented by SC-SH or "DMTD". Examples include 2,5-dimercapto-1,3,4 thiadiazole (DMTD) and 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole, and trithiocyanuric acid (TMT). Other examples include N-, S- and N,N-, S,S- and N,S-substituted derivatives of DMTD, such as 5-mercapto-3-phenyl-1,3,4-thiadiazoline-2-thione or bismuthiol II (3-phenyl-1,3,4-thiadiazolidine-2,5-dithione), and various S-substituted derivatives of trithiocyanuric acid. Other examples include polymers of 5,5'-dithio-bis(1,3,4-thiadiazole-2(3H)-thione, or DMTD (DMTD). 2 or (DMTD); 5,5'thio-bis(1,3,4 thiadiazole-2(3H)-thione; or dimers and polymers of TMT (TMT) 2 Other examples include the general formula: M(DMTD) n (Wherein, n=1, 2 or 3, and M is a metal cation such as M=Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I, Sb(III), Sn(II), Fe(II) or Cu(II) (e.g., ZnDMTD, Zn(DMTD) 2 , Bi(DMTD) 3 )) salts of DMTD; analogous salts of TMT in a 1:1 ratio, such as ZnTMT; and also comparable soluble Li(I), Ca(II), Sr(II), Mg(II), La(III), Ce(III), Pr(III) or Zr(IV) salts. Additional examples include salts of the general formula M[(DMTD) n ] mwhere n=2 or n>2, m=1, 2 or 3, and M is a metal cation, e.g., M=Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I), Sb(III), Sn(II), Fe(II) or Cu(II). A typical example is Zn[(DMTD) 2 ], Zn[(DMTD) 2 ] 2 It is.

[0054] Additional examples include DMTD, (DMTD) n or 5,5'thio-bis(1,3,4 thiadiazole-2(3H)-thione or 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole. Typical examples include cyclohexylamine:DMTD in ratios of 1:1 and 2:1; di-cyclohexylamine:DMTD in ratios of 1:1 and 2:1; aniline:DMTD in ratios of 1:1 and 2:1; analogous salts of TMT (e.g. di-cyclohexylamine:TMT) in a ratio of 1:1. Further examples include DMTD or (DMTD) formed with polyamines. n and polyammonium salts of TMT.

[0055] Further examples include DMTD or (DMTD) 2 or 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione and intrinsically conductive polyaniline doped with TMT; DMTD, (DMTD) 2 and intrinsically conductive polypyrroles and / or polythiophenes doped with 5,5′-thio-bis(1,3,4-thiadiazole-2(3H)-thione and / or TMT.

[0056] Further examples include polyDMTD / polyaniline, polyDMTD / polypyrrole and polyDMTD / polythiophene micro- or nanocomposites; similar micro- or nanocomposites with TMT; and with 5,5'thio-bis(1,3,4 thiadiazole-2(3H)-thione); DMTD or salts of DMTD or derivatives of DMTD and TMT as organic components of various pigment grade inorganic matrices or physical mixtures. In some embodiments, such inorganic matrices contain anionic and cationic species with corrosion inhibitor properties, e.g., MoO 4 - , P.O. 4 - , H.P.O. 3 - , Poly-phosphate, BO 2 - , SiO 4 - , N.C.N. - , WO 4 - , phosphomolybdate, and phosphotungstate, and respectively Mg, Ca, Sr, La, Ce, Zn, Fe, Al, and Bi.

[0057] Further examples include DMTD or salts of DMTD or derivatives of DMTD and TMT in encapsulated form (eg, as inclusion bodies within various polymer matrices or as cyclodextrin inclusion compounds) or in microencapsulated form.

[0058] DMTD in pigment grade form is Zn(DMTD) with inorganic products or corrosion inhibitor pigments 2 and Zn-DMTD (among other organic and inorganic salts of the former), including phosphates, molybdates, borates, silicates, tungstates, phosphotungstates, phosphomolybdates, cyanamides or carbonates, and oxides of the aforementioned cationic species. Examples include zinc phosphate, cerium molybdate, calcium silicate, strontium borate, zinc cyanamide, cerium phosphotungstate, ZnO, CeO 2 , ZrO 2 , and amorphous SiO2 Includes:

[0059] The method 200 includes introducing iron particles (e.g., carbonyl iron powder) into the passivation solution (block 204) to form iron particles fully or partially coated (e.g., encapsulated) in the passivation agent. Alternatively, block 204 may include introducing iron particles into a solvent to form an iron particle solution, and subsequently introducing a passivation agent into the iron particle solution to form iron particles fully or partially coated (e.g., encapsulated) in the passivation agent. The introducing (block 204) may include gently mixing the iron particles into the passivation solution or the iron particle solution using any suitable stirring device, such as a stirring bar or stirring propeller or vortex stirrer. The stirring may be performed in a Roller Mixer to provide a gentle mixing environment. Overly aggressive mixing (or exposure to harsh chemicals in solutions such as acid solutions with a pH of about 3 or base solutions with a pH of about 11 (e.g., ammonium hydroxide)) can oxidize the iron particles and degrade their magnetic properties. For example, mixing iron particles with concentrated 2,5-dimercapto-1,3,4-thiadiazole (DMcT) in a Thinky Mixer can erode the iron particles. Additionally, some thiol compounds can be considered acidic and / or basic. For example, DMcT is acidic, and exposure of the iron particles to concentrated DMcT solutions for too long can erode the iron particles.

[0060] In at least one embodiment, the weight ratio (g / g) of passivation agent to iron particles is from about 0.01:1 to about 1:0.01, such as from about 0.05:1 to about 0.5:1, such as from about 0.1:1 to about 0.4:1, such as about 0.11:1.

[0061] The passivation solution or the iron particle solution can be heated before and / or during the introduction of the iron particles into the passivation solution. In at least one embodiment, the method includes heating the passivation solution to a temperature of about 20° C. to about 120° C., such as about 40° C. to about 80° C., such as about 60° C. In at least one embodiment, the method includes heating the iron particle solution to a temperature of about 20° C. to about 120° C., such as about 40° C. to about 80° C., such as about 60° C.

[0062] In at least one embodiment, the stirring / mixing is performed at a stirring / shaking speed of about 50 revolutions per minute (rpm) to about 5000 rpm, e.g., about 300 rpm to about 2000 rpm. In at least one embodiment, the mixing is performed for a period of about 10 seconds to about 1 hour, e.g., about 30 seconds to about 5 minutes.

[0063] The method 200 includes removing the coated iron particles from the passivation solution (Block 206). The removal can be performed using any suitable filtration setup, such as a filter paper or a wire mesh filter. In at least one embodiment, the method includes filtering the coated iron particles. The filter paper or wire mesh can have an average pore size of 100 microns or less, such as about 0.1 microns to about 50 microns, such as about 3 microns to about 20 microns, such as about 11 microns (Grade 1). Increased or decreased pressure (e.g., vacuum) can be applied to the filtering setup to facilitate filtering the coated iron particles as filtered off and the solvent as filtrate. The method 200 further includes washing the filtered coated particles with a solvent (Block 208). In at least one embodiment, the solvent is one or more of an alcohol (e.g., isopropanol, ethanol, or methanol), an alkane (e.g., hexane), or an alkyl carbonate (e.g., dimethyl carbonate, diethyl carbonate, or dipropyl carbonate).

[0064] The method 200 includes drying the coated iron particles (Block 210). Drying can be performed with a filter cloth, towels, and / or compressed air / inert gas. Inert gas includes nitrogen and / or argon. Drying can alternatively or additionally be performed by curing the coated iron particles at room temperature or at an elevated temperature. In at least one embodiment, the method includes drying the coated iron particles by curing the particles at a temperature of about 10° C. to about 150° C., such as about 20° C. to about 100° C., such as about 30° C. to about 70° C., such as about 40° C. to about 50° C. Curing can be performed for a period of about 15 minutes to about 72 hours. EXAMPLES

[0065] Example 1: material 1. 2,5-Dimercapto-1,3,4-thiadiazole (DMcT), molecular weight: 150.232 g / mol (Acros). 2. Vanlube 829, 871 and 972M were obtained from RT Vanderbilt. 3. Carbonyl iron powder (CIP) HQ was obtained from BASF.

[0066] Roller mill sample preparation DMcT-CIP: Dissolve 3 grams of DMcT in 150.85 grams of degassed isopropanol (density 0.786 g / cm 3 ) to give a 2.0 wt.% or 0.104M solution. Dispersions of CIP were prepared in small glass vials as described in Table 1. All solutions were degassed with nitrogen. The vials were mixed using a roller mill for three days.

[0067] TIFF0007658710000003.tif78170

[0068] TIFF0007658710000004.tif63170

[0069] After milling, the IPA was removed from the vial using a rotovap with a dedicated adapter to accommodate the vial. The above samples were evaluated for corrosion resistance to 5% NaCl (pH 2.9) acetic acid. A piece of filter paper was placed at the bottom of the vial and a small amount of powdered sample was sprinkled on top of the filter paper. A few drops of acidified NaCl solution were then added on top of the sample to saturate the filter paper. The vial was then sealed with a screw cap top and allowed to react for 24 hours. It was observed that the highest rate of DMcT / CIP exhibited corrosion protection compared to the other samples. Other examples and data using the Thinky orbital mixer provided similar results.

[0070] Orbital mixer preparation of DMcT-CIP 25.33 grams of CIP was mixed with 140.38 grams of 0.1M DMcT in IPA and mixed using a Thinky mixer. 11 to 15 gram samples were taken from the mixing vessel at intervals as shown in Table 2 and placed in sealed vials.

[0071] TIFF0007658710000005.tif72170

[0072] The samples were separated from the DMcT IPA solution by vacuum filtration through a 0.2 micron Teflon filter and washed with IPA. The samples were tested for corrosion resistance to acetic acid at pH 2.8 in 5% NaCl by saturating a piece of filter paper with the solution and sprinkling it on the CIP powder and compared to a control. The samples were placed in a sealed container and visible corrosion, i.e., brown rust formation, was compared between the samples after 24 hours of exposure.

[0073] Orbital Mixer Preparation of VL829-CIP 5.96 grams of Vanlube 829 (VL829) (FW=298.48) was dispersed in 200 ml of 1M ammonium hydroxide to obtain a 1.0M solution. The solution was heated to boiling. After 10 minutes, the solution changed color from dark yellow to very light yellow. The solution was passed through a 1 micron vacuum filter to remove any undissolved material (which was minimal, if any). 24.62 grams of CIP was added to the VL829 ammonium hydroxide solution and mixed in the Thinky at 1100 RPM with samples taken at 29.5 minute intervals as shown in Table 3. From Table 1, the weight ratio of DMcT to CIP is 0.11.

[0074] TIFF0007658710000006.tif54170

[0075] The collected samples were allowed to settle and the supernatant was decanted. The wet powder was then dried overnight at 60° C. under vacuum. The samples were tested for corrosion resistance to acetic acid at pH 2.8 in 5% NaCl. Samples 1-3 showed some improvement in corrosion protection.

[0076] Sonication methods for the Vanlube 871 and 972M. Vanlube 871 and 972M were also evaluated as coating formulations for CIP. Vanlube 972M is a thiadiazole derivative in polyalkylene glycol and Vanlube 871 is a 2,5,dimercapto-1,3,4-thiadiazole alkyl carboxylate. In this case, both materials were dispersed with CIP and isopropanol and sonicated as described in Table 4.

[0077] TIFF0007658710000007.tif49170

[0078] The coated CIPs were removed from the solution, air dried and tested for corrosion resistance. VL972M offered better corrosion protection than VL871.

[0079] Orbital mixer preparation of IC 1000-CIP 7.2 grams of Inhibicor 1000 (Wayne Pigments) was mixed into 200 ml of 0.1M ammonium hydroxide and boiled for 15 minutes. It was then placed on a roller mill and mixed over the weekend. After filtration, a white powder remained on the filter and the filtrate was yellow. 10 grams of CIP was mixed with 200 ml of the filtrate and mixed at 1100 RPM in a Thinky orbital mixer and samples were taken at 29.5 minutes, 59 minutes, and 88.5 minutes. The samples were filtered, rinsed with DI water, and air dried. They were then evaluated for corrosion resistance. Results showed that sample 2 (the 59 minute sample) exhibited the best corrosion resistance. Upon further investigation, it appears likely that the yellow filtrate is DMcT and the white powder is zinc oxide / hydroxide. Thus, this experiment evaluated the effect of DMcT in ammonium hydroxide.

[0080] Example 1 observation: 1. DMcT-CIP was prepared from a solution of DMcT in IPA using a roller mill and an orbital Thinky mill. 2. DMcT-CIP with a weight ratio of 0.11, prepared using the orbital mixing method in IPA, was shown to significantly improve the corrosion resistance of CIP iron particles when exposed to acidic salt solutions. 3. VL829-CIP exhibited marginal corrosion protection performance when prepared using the orbital mixing method in ammonium hydroxide. 4. When IPA was used as the diluent, the performance of VL972M was higher than VL871 but somewhat lower than DMcT when using the sonication method. 5. The roller milling method was shown to be a superior method to the Thinky method when coating particles with DMcT using IPA as the solvent.

[0081] Additionally, Figures 3A, 3B, and 3C are scanning electron microscope images of carbonyl iron particles without thiol passivation. The particles are substantially spherical. Figures 4A, 4B, and 4C are scanning electron microscope images of carbonyl iron particles passivated with DMcT. Many of the particles are rectangular in shape, and many others are spherical.

[0082] In addition, the SEM backscattered electron images show the compositional contrast resulting from elements with different atomic numbers and their distribution. Energy dispersive spectroscopy (EDS) allows identification of these specific elements and their percentages (e.g. atomic %). Figure 5A shows the EDS spectrum of the SEM images of the carbonyl iron particles of Figures 3A-3C. As shown in Figure 5A, the sulfur content in these particles is zero. Figure 5B shows the EDS spectrum of the SEM images of the DMcT passivated iron particles of Figures 4A-4C. As shown in Figure 5B, the particles contain a substantial amount of sulfur content, which indicates a thiol passivation layer deposited thereon.

[0083] Example 2: Further testing of the coated particles was performed using SO 2 , which has a lower pH (3) and is considered a very aggressive test. 2 The test was performed under spray (ASTM B117). No corrosion was observed and the particle pack exhibited magnetic susceptibility.

[0084] Example 3: The coated CIP particles were formulated into a polyurethane coating. Tests were run on this coating placed on polycarbonate in a standard salt spray cabinet for 500 hours. Such panels show no signs of corrosion. The coating does not interfere with the magnetic properties of the iron particles. A control was run which failed.

[0085] Example 3 material: 1. Modified and unmodified CIP powders 2. PPG Polyurethane PR1664 Base (Part B) and 73008-001 (Part A); 10:1 weight ratio 3. Dimethyl carbonate (DMC) solvent 4.3x5 Polycarbonate (PC) Panel

[0086] Example 3 device: 1. Thinky Mixer (Continuous setting) 500RPM for 30 seconds, 1000RPM for 30 seconds, 1500RPM for 30 seconds 2. Disposable 200ml polypropylene cups

[0087] Example 3 Procedure (for modified and unmodified CIP): 1. Dissolve 50 grams of Part B in 60 grams of DMC in a 200 ml disposable cup. 2. 50 grams of CIP was added to the above solution. 3. Thinky was run each time the above program was run. 4.5 grams of Part A was added to the mixed dispersion. 5. Thinky was run each time the above program was run. 6. Contents transferred to a spray bottle and diluted with DMC as needed to achieve a sprayable viscosity. 7.10 PC panels were sprayed. The formulations were sprayed immediately after mixing. 8. The coated panels were allowed to air dry for 24 hours.

[0088] Example 3 Observations: Figure 6A is a photograph of a panel coated with a polyurethane coating having unmodified carbonyl iron particles. The coated panel was exposed to salt spray for 1000 hours according to ASTM B117. As shown in Figure 6A, substantial corrosion is observed. Figure 6B is a photograph of a panel coated with a polyurethane coating having thiol-coated iron particles. The coated panel was exposed to salt spray for 1000 hours according to ASTM B117. As shown in Figure 6A, there is no observable corrosion of the panel.

[0089] Overall, the coated iron particles and compositions of the present invention provide iron particles that are less susceptible to corrosion and that maintain their magnetic properties after passivation. Furthermore, unlike conventional coated iron particles, the coated iron particles and compositions of the present invention are well dispersed (e.g., do not clump) uniformly compared to unpassivated iron particles. The method of forming the coated iron particles of the present invention provides a simple (e.g., three-step) process that uses relatively inexpensive materials, all of which reduces manufacturing time and costs compared to conventional iron coating methods.

[0090] definition The term "alkyl" includes substituted or unsubstituted straight or branched acyclic alkyl radicals containing from 1 to about 20 carbon atoms. In at least one embodiment, alkyl includes straight or branched C 1-20 Contains alkyl. 1-20 Alkyl includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosanyl, and structural isomers thereof.

[0091] The term "cycloalkyl" embraces substituted or unsubstituted cyclic alkyl radicals containing 1 to about 20 carbon atoms.

[0092] The term "aryl" refers to any monocyclic, bicyclic, or tricyclic carbocyclic ring of up to six atoms in each ring, in which at least one ring is an aromatic or aromatic ring system of 5 to 14 carbon atoms containing a carbocyclic aromatic group fused to a 5- or 6-membered cycloalkyl group. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, anthracenyl, or pyrenyl.

[0093] The term "alkoxy" refers to RO--, where R is alkyl as defined herein. The terms alkyloxy, alkoxyl, and alkoxy can be used interchangeably. Examples of alkoxy include, but are not limited to, methoxyl, ethoxyl, propoxyl, butoxyl, pentoxyl, hexyloxyl, heptyloxyl, octyloxyl, nonyloxyl, decyloxy, and structural isomers thereof.

[0094] The term "ether" is an oxygen atom bridging two carbon atoms.

[0095] The term "thione" has the structure -CR 2 -(C=S)-CR 2 -, where each R is independently hydrogen, alkyl, acyl, heteroalkyl, aryl, cycloalkyl, heteroaryl, or heterocycloalkyl.

[0096] The term "heterocyclyl" refers to monocyclic, bicyclic, or tricyclic rings having up to 10 atoms in each ring, in which at least one ring is aromatic and contains from 1 to 4 heteroatoms in the ring selected from N, O, and S. Non-limiting examples of heterocyclyl include pyridyl, thienyl, furanyl, pyrimidyl, imidazolyl, pyranyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, oxazolyl, isoxazoyl, pyrrolyl, pyridazinyl, pyrazinyl, quinolinyl, isoquinolinyl, benzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzothienyl, indolyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, isoindolyl, benzotriazolyl, purinyl, thianaphthenyl, pyrazinyl, azole, triazole, thiazole, dithiazole, and thiadiazole. Attachment of a heterocyclyl can occur via an aromatic ring or via a non-aromatic ring or a ring that does not contain a heteroatom.

[0097] The term "amino" refers to a primary, secondary, or tertiary amine-containing radical. An example of an amino radical is -NH 2 The amino radical is R 4 or R 5 (for example, TIFF0007658710000008.tif21170), where R 4 R can be, for example, cyano, haloacyl, alkenylcarbonyl, hydroxyalkenylcarbonyl, aminoalkenylcarbonyl, monoalkylaminoalkenylcarbonyl, dialkylaminoalkenylcarbonyl, haloalkenylcarbonyl, cyanoalkenylcarbonyl, alkoxycarbonylalkenylcarbonyl, alkynylcarbonyl, hydroxyalkynylcarbonyl, alkylcarbonylalkenylcarbonyl, cycloalkylcarbonylalkenylcarbonyl, arylcarbonylalkenylcarbonyl, aminocarbonylalkenylcarbonyl, monoalkylaminocarbonylalkenylcarbonyl, dialkylaminocarbonylalkenylcarbonyl or alkenylsulfonyl; R 5 can be, for example, H, alkyl or cycloalkyl.

[0098] The compounds of the present invention include tautomeric, geometric, or stereoisomeric forms of the compounds. Ester, oxime, onium, hydrate, solvate, and N-oxide forms of the compounds are also included in the present invention. The present invention contemplates all such compounds, including cis- and trans-geometric isomers (Z- and E-geometric isomers), R- and S-enantiomers, diastereomers, d-isomers, l-isomers, atropisomers, epimers, conformers, rotamers, mixtures of isomers, and racemates thereof.

[0099] Furthermore, the present invention includes embodiments according to the following provisions: Clause 1. Iron particles having a diameter of about 0.5 microns to about 1000 microns; and Thiol coating on iron particles or a reaction product thereof. Clause 2. The coated iron particles of clause 1 having a diameter of about 1 micron to about 1000 microns. Clause 3. The coated iron particles of clause 2, having an iron content of about 99 wt% or greater. Clause 4. The coated iron particles of any one of clauses 1 to 3, wherein the thiol coating has a thickness of about 10 Angstroms to about 1000 Angstroms. Clause 5. The coated iron particles of clause 4, having a thiol coating content of about 1 vol.% to about 10 vol.%, based on the total volume of the thiol-coated iron particles, as determined by the difference in weight and density of the particles before and after coating the particles. Clause 6. The coated iron particles of clause 4, having a thiol coating content of about 1 wt.% to about 10 wt.%, based on the total weight of the thiol-coated iron particles, as determined by the difference in weight of the particles before and after coating the particles. Clause 7. The coated iron particles of clause 6, having a thiol coating content of about 2 wt.% to about 5 wt.%, based on the total weight of the thiol-coated iron particles, as determined by the difference in weight of the particles before and after coating the particles. Article 8. χ of about 0.5:1 to about 1.5:1 s 8. The coated iron particles of any one of clauses 1 to 7, having a ratio of: Clause 9. The coated iron particles of any one of clauses 1 to 8, wherein the thiol coating comprises or is a reaction product of a thiol compound selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols. Clause 10. The coated iron particle of clause 9, wherein the thiol coating comprises or is a reaction product of an alkyl polythiol selected from ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, hexanedithiol, pentanedithiol, octanedithiol, nonanedithiol, and decanedithiol. Clause 11. The coated iron particle of clause 9, wherein the thiol coating comprises or is a reaction product of a heterocyclic thiol that is 2,5-dimercapto-1,3,4-thiadiazole. Clause 12. Coated iron particles according to any one of clauses 1 to 11; and Polymer or Adhesion Promoter or a reaction product thereof. Clause 13. The composition of clause 12, comprising a polymer selected from an epoxy, a bismaleimide, a polyimide, a polyaryletherketone, a sol-gel, a polyurethane, a silicone, or a magnetorheological particle fluid. Clause 14. The composition of clause 13, having a coated iron particle content of about 0.5 wt% to about 10 wt%. Clause 15. A composition comprising a surface and, deposited on said surface, the composition of any one of clauses 12 to 14. Clause 16. A method for passivating iron particles comprising: introducing a passivation agent having one or more sulfur moieties into a solvent to form a passivation solution; and contacting iron particles having a diameter of about 0.5 microns to about 1000 microns with a passivation solution to form coated iron particles; The method includes: Clause 17. The method of clause 16, wherein introducing the passivation agent into a solvent comprises introducing the passivation agent into a solvent selected from an alcohol, an alkyl carbonate, an ether, a glycol ether, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide, or a mixture thereof. Clause 18. The method of clause 17, wherein the concentration of the passivation agent in the passivation solution is from about 1M to about 2M. Clause 19. The method of any one of clauses 16 to 18, wherein the passivation agent is selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols. Clause 20. The method of clause 19, wherein contacting the iron particles with the passivation solution includes introducing the iron particles into the passivation solution to form a solution including the passivation agent and the iron particles. Clause 21. The method of clause 20, further comprising agitating the solution comprising the passivation agent and the iron particles. Clause 22. The method of clause 21, further comprising heating the passivation solution to a temperature of about 40° C. to about 80° C. prior to introducing the iron particles into the passivation solution. Clause 23. The method of any one of clauses 16 to 22, further comprising filtering the coated iron particles and drying the coated iron particles by curing at a temperature of about 30° C. to about 70° C. Clause 24. A method for passivating iron particles comprising: introducing iron particles having a diameter of about 0.5 microns to about 1000 microns into a solvent to form an iron particle solution; and contacting a passivation agent having one or more sulfur moieties with a solution of iron particles to form coated iron particles; The method includes: Clause 25. The method of clause 24, wherein introducing the iron particles into a solvent comprises introducing the iron particles into a solvent selected from an alcohol, an alkyl carbonate, an ether, a glycol ether, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide, or a mixture thereof. Clause 26. The method of clause 25, wherein contacting the passivation agent with the iron particle solution comprises introducing the passivation agent into the iron particle solution to form a solution comprising the passivation agent and the iron particles. Clause 27. The method of clause 26, further comprising heating the iron particle solution to a temperature of from about 40°C to about 80°C. Clause 28. The method of clause 27, further comprising filtering the coated iron particles and drying the coated iron particles by curing at a temperature of about 30°C to about 70°C.

[0100] The description of the various aspects of the present disclosure is provided for illustrative purposes and is not intended to be exhaustive or limited to the disclosed aspects. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described aspects. The terms used herein are selected to best explain the principles, practical applications or technical improvements of the aspects with respect to the art found in the marketplace, or to enable those skilled in the art to understand the aspects disclosed herein. While the above is directed to aspects of the present invention, other and further aspects of the invention may be devised without departing from its basic scope.

Claims

1. Iron particles having a diameter of 0.5 micrometers to 1000 micrometers; and Thiol coating on iron particles wherein the thiol coating comprises a thiol compound selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols.

2. 10. The coated iron particles of claim 1 having an iron content of 99 wt% or greater.

3. 3. The coated iron particles of claim 1 or 2, wherein the thiol coating has a thickness of from 1 nanometer to 100 nanometers.

4. 4. The coated iron particles of claim 3, wherein the coated iron particles have a thiol coating content of 1 vol.% to 10 vol.%, based on the total volume of the thiol-coated iron particles, when the thiol coating content is determined by the difference in weight and density of the particles before and after coating the particles.

5. 4. The coated iron particles of claim 3, wherein the coated iron particles have a thiol coating content of 1 wt. % to 10 wt. %, based on the total weight of the thiol-coated iron particles, when the thiol coating content is determined by the difference in weight of the particles before and after coating the particles.

6. 2. The coated iron particles of claim 1, wherein the thiol coating comprises an alkyl polythiol selected from ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, hexanedithiol, pentanedithiol, octanedithiol, nonanedithiol, and decanedithiol.

7. 2. The coated iron particles of claim 1, wherein the thiol coating comprises a heterocyclic thiol that is 2,5-dimercapto-1,3,4-thiadiazole.

8. Coated iron particles according to any one of claims 1 to 7; and polymer A composition comprising:

9. 9. The composition of claim 8 comprising a polymer selected from an epoxy, a bismaleimide, a polyimide, a polyaryletherketone, a sol-gel, a polyurethane, a silicone, or particles dispersed in a hydrocarbon oil, a silicone oil, a water phosphate ester fluid, or a synthetic oil.

10. 10. The composition of claim 9 having a coated iron particle content of 0.5 wt% to 10 wt%.

11. 11. A component comprising a surface and a composition according to any one of claims 8 to 10 deposited on said surface.

12. 1. A method for passivating iron particles, comprising: introducing a passivation agent having one or more sulfur moieties into a solvent to form a passivation solution; and contacting iron particles having a diameter of 0.5 micrometers to 1000 micrometers with a passivation solution to form coated iron particles; wherein the passivation agent is selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols.

13. 13. The method of claim 12, wherein introducing the passivation agent into a solvent comprises introducing the passivation agent into a solvent selected from an alcohol, an alkyl carbonate, an ether, a glycol ether, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide, or a mixture thereof.

14. The method of claim 12, wherein the concentration of the passivation agent in the passivation solution is from 1M to 2M.

15. 15. The method of claim 14, wherein contacting the iron particles with the passivation solution comprises introducing the iron particles into the passivation solution to form a solution comprising the passivation agent and the iron particles.

16. The method of claim 15 further comprising agitating the solution containing the passivation agent and the iron particles.

17. 17. The method of claim 16, further comprising heating the passivation solution to a temperature of from 40°C to 80°C prior to introducing the iron particles into the passivation solution.

18. 18. The method of any one of claims 12 to 17, further comprising filtering the coated iron particles and drying the coated iron particles by curing at a temperature of from 30°C to 70°C.

19. 1. A method for passivating iron particles, comprising: introducing iron particles having a diameter of 0.5 micrometers to 1000 micrometers into a solvent to form an iron particle solution; and contacting a passivation agent having one or more sulfur moieties with a solution of iron particles to form coated iron particles; wherein the passivation agent is selected from heterocyclic thiols, disulfide compounds, thiolate compounds, and alkyl polythiols.

20. 20. The method of claim 19, wherein introducing the iron particles into the solvent comprises introducing the iron particles into a solvent selected from an alcohol, an alkyl carbonate, an ether, a glycol ether, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide, or a mixture thereof.

21. 21. The method of claim 20, wherein contacting the passivation agent with the iron particle solution comprises introducing the passivation agent into the iron particle solution to form a solution comprising the passivation agent and the iron particles.

22. 22. The method of claim 21, further comprising heating the iron particle solution to a temperature of from 40°C to 80°C.

23. 23. The method of claim 22, further comprising filtering the coated iron particles and drying the coated iron particles by curing at a temperature of from 30° C. to 70° C.

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