KR20110026574A - Ferromagnetic nanoparticles with high magnetocrystalline anisotropy for micr ink applications - Google Patents

Abstract

PURPOSE: An ink is provided to ensure excellent stability, dispersibility and magnetic property compared with ink containing magnetite by comprising stabilized magnetic monocrystal nano particles. CONSTITUTION: An ink comprises a carrier, selective coloring agent and stabilized magnetic mono-crystal nanoparticles. The absolute value of magnetocrystalline anisotropy of magnetic nano particles is 2 × 10^4 J/m^3 or more. The average particle size of the magnetic nano particles is 10-300 nm. A ratio(D_major/D_minor) of big axis to small axis is less than 4:1.

Description

FERROMAGNETIC NANOPARTICLES WITH HIGH MAGNETOCRYSTALLINE ANISOTROPY FOR MICR INK APPLICATIONS}

The present invention relates to a MICR inkjet ink comprising stabilized magnetic single crystal nanoparticles, wherein the absolute value (| K1 |) of magnetic anisotropy of the magnetic nanoparticles is not less than 2 x 10 ⁴ J / m ³ . The magnetic nanoparticles may be ferromagnetic nanoparticles such as FePt. The ink contains magnetic particles that minimize the size of the particles, resulting in good magnetic pigment dispersion and dispersion stability, especially in water-insoluble inkjet inks. Smaller size magnetic ink particles also maintain good magnetic properties, thereby reducing the magnetic particle loading required in the ink.

There have been many opportunities to develop MICR inkjet inks. First, if not all, inkjet printers considerably limit the particle size of any particulate components of the ink due to the very small size of the inkjet print head nozzle that extracts the ink onto the substrate. Inkjet head nozzles are generally similar in size to about 40-50 microns, but may be less than 10 microns. This small nozzle size indicates that the particulate material contained in any inkjet ink composition intended for use in an inkjet printer should be of very small particle size to avoid nozzle clogging problems. However, even when the particle size is smaller than the nozzle size, the particles may still be agglomerated or dense in a range where the size of the mass exceeds the size of the nozzle, and as a result, the nozzle is blocked. Additionally, particulate material may be deposited at the nozzle during printing, thereby forming crusts that result in nozzle blockage and / or defective flow parameters.

 Another concern with the formulation of MICR inkjet inks is that the ink is fluid and should not dry out. Therefore, an increase in pigment size results in a consistent increase in density, thereby making it difficult to maintain the dye in suspension and dispersion in the liquid ink composition.

MICR inks include magnetic materials that provide the necessary magnetic properties. It is essential for the magnetic material to have sufficient magnetic charge so that the printed characters retain their readable characteristics and are easily detected by the detection device or the reader. Magnetism retained by a magnetic material is known as "remanence". "Coercive force" of a magnetic material refers to a magnetic field H that must be applied to the magnetic material in a symmetrical form that is periodically magnetized to dissipate the magnetic induction. Therefore, the coercivity of the magnetic material is the coercive force of the material in the hysterisis loop and its maximum induction is close to the saturation induction. The observed residual magnetization and the observed coercive force of the magnetic material depend on the magnetic material having some anisotropy to provide the desired orientation for the magnetic moment in the crystal. The four major anisotropic forces of magnetic anisotropy, strain anisotropy, exchange anisotropy, and shape anisotropy determine the particle antimagnetic forces. The two main anisotropies are: 1) shape anisotropy where the desired magnetic orientation is along the axis of the magnetic crystal, and 2) aligning the axis and magnetic moment of the crystal structure where electron spin-orbit coupling is desired. It is self-crystalline anisotropy.

The magnetic material must exhibit sufficient residual magnetism when exposed to a source of magnetization to generate a MICR-readable signal and have the ability to hold the same over time. In general, the acceptable level of self as set by industry standards is 50 to 200 signal level structural units, where 100 is a nominal value defined from a standard developed by the American National Standards Institute (ANSI). Less signals may not be detected by the MICR reading device, and larger signals may give accurate readings. Since the documents to be read employ MICR printed characters as a means of verifying or verifying the documents present, it is essential that the MICR characters or other representations are read correctly without randomly reading or being read any characters. Therefore, for the purpose of MICR, the residual magnetism should be at least 20 emu / g. Higher residual magnetic values correspond to stronger readable signals.

Residual magnetism tends to increase as a function of particle size and density of the magnetic dye coating. Thus, when the magnetic particles decrease, the magnetic particles tend to correspondingly reduce the residual magnetism. Therefore, as the magnetic particle size is reduced and a practical limit on the percentage content of magnetic particles in the ink composition is reached, it becomes more difficult to achieve sufficient signal strength. Higher residual magnetic values require less overall percentage of magnetic particles in the ink formula and reduce the likelihood of settling compared to ink formulations with higher percentages of magnetic particle content.

In addition, MICR inkjet inks have a jet temperature for proper functioning in both drop-on-demand printing facilities such as thermal bubble jet printers, piezoelectric printers, and continuous printing mechanisms. The ejection temperature should range from about 25 ° C. to about 140 ° C.), with a low viscosity similar to less than about 15 cP or similar to about 2-8 cP. However, the use of low viscosity fluids adds to the concern of successfully incorporating magnetic particles into ink dispersion since particle fixation increases in thinner fluids of low viscosity compared to thicker fluids of higher viscosity.

Magnetite (iron oxide, Fe ₂ O ₃ ) is a common magnetic material used in MICR inkjet inks. Magnetite has low self-crystallization anisotropy (K1) of -1.1 x 10 ⁴ J / m ³ . Acicular crystalline magnetite with one crystal dimension much larger than the other has a greater than 2: 1 aspect ratio (D _major / D _minor , aspect ratio) of the large size axis to the small size axis of the single crystal, Helps to increase the residual magnetic and coercive force performance. Needle magnetite is typically 0.6 x 0.1 microns in size along the small and large axes, and has a large shape anisotropy (6/1). Typical loadings of iron oxide in the ink are 20 to 40 wt%. However, due to the larger size and aspect ratio of the precipitated crystalline magnetic particles, the particles are difficult to disperse and stabilize in ink, especially for use in ink jet printing. In addition, spherical or cubic magnetite has a small size (less than 200 nm in all dimensions), but has a low shape anisotropy (D _major / D _minor ) of about 1. As a result, because of the low overall anisotropy, the spherical or cube magnetite has low residual magnetism and coercive force, and sometimes a loading greater than 40wt% is needed to provide magnetic performance. Therefore, although spherical and cubular magnetite have the required small particle size of less than 200 nm in all dimensions, much larger loading requirements make it very difficult for the particles to diffuse and maintain stable diffusion. In addition, this high loading of inert, non-melting magnetic material degrades other ink properties such as adhesion to the substrate and scratch resistance. As a result, this worsens the suitability of magnetite for inkjet printing inks.

Additionally, because magnetite has a specific gravity of approximately 7, magnetite has a natural property of settling to the bottom of the fluid ink composition. This creates a heterogeneous fluid having an iron oxide enrichment bottom layer and an iron oxide poverty top layer. Moreover, suitable inkjet oxides should be naturally hydrophilic in order to provide good dispersion properties and good emulsion properties. The latter parameter is directly related to the ability of the magnetic particles to exhibit minimal settling and also to demonstrate proper wetting of the magnetic particles with other water soluble components present in the inkjet ink composition.

Commonly related problems with the use of iron oxides in MICR inkjet inks have been addressed in several different ways. For example, it is known to use combinations of surfactants with metal oxide components of very small size for the purpose of maintaining useful suspensions or dispersions of magnetic components in ink compositions. Another means of achieving inkjet inks suitable for use in inkjet printers and also for generating MICR readable printing is to coat the metallic magnetic material with a specific hydrophilic coating to help retain the magnetic metal of the particles in suspension. .

Yet another type of ink used for MICR inkjet printing is xFerrone ^™ (Iron Composite Dye) Ink, which is a water soluble ink commercialized by G7 Productivity Systems, Inc. (VersaInk ^™ ). These inks can be compatible with HP®, Canon®, Lexmark®, Dell® and Epson® printers and have a variety of uses, for example, to ensure reliable scanning of checks and to eliminate delays at the checkout counter.

However, such inks do not exhibit the properties of reduced size magnetic material particles with good magnetic dye dispersion and dispersion stability, and particles that contain reduced particle loading requirements and also maintain good magnetic properties. This is because the large axis / small axis of the magnetic particles used in the conventional ink should have an aspect ratio of at least 2: 1, and therefore, the particle size of acicular magnetite is 0.6 micron for the large axis. This results in poor dispersion and poor dispersion stability.

It is an object of the present invention to provide a MICR inkjet ink comprising stabilized magnetic single crystal nanoparticles.

In general, the present invention relates to inks comprising magnetic nanoparticles exhibiting large anisotropy dispersed in a carrier medium. The ink may further comprise one or more resins, one or more colorants, and / or one or more additives. In one embodiment, the magnetic nanoparticles are metal nanoparticles. In another embodiment, the magnetic nanoparticles are single crystal ferromagnetic nanoparticles. Inks are suitable for use in a variety of applications, including MICR applications. In addition, the printed ink can be used for decorative purposes even though the resulting ink does not sufficiently exhibit coercive force and residual magnetism suitable for use in MICR ink applications. The ink of the present invention exhibits better stability, dispersion characteristics, and magnetic properties than inks containing magnetite. Ink compositions are described in detail.

The present invention is not limited to the specific examples described herein, and some components and processes may be changed by those skilled in the art based on this application. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

In the description and claims, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates.

In the description and claims, the following "inks" are referred to as "ink compositions" and vice versa.

Magnetic materials suitable for use in the present invention include single crystal nanoparticles that exhibit large anisotropy. As used herein, “large anisotropy” is defined as the absolute value of the self-crystallization anisotropy of a particle, which is at least 2 × 10 ⁴ J / m ³ . Suitable magnetic materials include about 5 x 10 ⁴ J / m 3 to about 5 x 10 ⁶ J / m 3 or about 7 x 10 ⁴ J / m 3 to about 4 x 10 ⁶ J / m ^3, although materials with higher K1 values are suitable. The same has a K1 value of about 2 x 10 ⁴ J / m 3 to about 5 x 10 ⁷ J / m 3. In embodiments, the single crystal nanoparticles may be magnetic metal nanoparticles, or ferromagnetic nanoparticles with large anisotropy including, for example, Co and Fe (cubic), among others. Additionally, the magnetic nanoparticles can be bimetallic, trimetallic, or mixtures thereof. Examples of such suitable binary metal magnetic nanoparticles include, but are not limited to, CoPt, fcc phase FePt, fcc phase fePt, FeCo, MnAl, MnBi, CoO · Fe ₂ O ₃ , BaO 6Fe ₂ O ₃ , mixtures thereof, and the like. In another embodiment, the magnetic nanoparticles are faceted tetragonal lattice FePt. Examples of ternary nanoparticles may include, without limitation, a ternary mixture of the magnetic nanoparticles, or a core / envelope structure forming ternary metal nanoparticles such as Co-coated interfacial tetragonal FePt.

Magnetic nanoparticles can be prepared by any method known in the art (conventional methods used to prepare nano-sized dyes), including ball-milling arrrition of larger particles, and then Annealed. Annealing is generally necessary because of the ball milling of amorphous nanoparticles that need to be later crystallized into the required single crystal form. Nanoparticles can also be made directly by RF plasma. Moderately large scale RF plasma reactors are manufactured by Tekna Plasma Systems. Nanoparticles can also be made by a number of methods in a solvent that includes water in situ.

The average particle size of the magnetic nanoparticles can be, for example, from about 10 nm to about 300 nm in all dimensions. Nanoparticles can be of any shape, including spheres, cubes, and hexagons. In one embodiment, the nanoparticles are about 10 nm to about 500 nm in size, such as about 50 nm to about 300 nm, or about 75 nm to about 250 nm, although the amount is outside of the following range: . Here, the “average” particle size is typically expressed as d ₅₀ or defined as the particle size in the median at the 50th percentile of the particle size distribution, with 50% of the particles in the distribution being d ₅₀ particle size Greater than the value, the other 50% of the particles in the distribution are less than the d ₅₀ value. Average particle size can be measured by methods using light scattering techniques to infer particle size, such as Dynamic Light Scattering. Particle diameter refers to the length of the dye particles as derived from the images of the particles generated by Transmission Electron Microscopy (TEM).

The ratio of the large axis (D _major / D _minor ) to the small axis of the single nanocrystal may be less than about 4: 1, such as less than about 3: 2, or less than about 2: 1.

The loading requirement of the magnetic nanoparticles in the ink may be about 0.5 wt% to about 15 wt%, such as about 5 wt% to about 10 wt%, or about 6 wt% to about 8 wt%, although the total may be out of the range below. .

Magnetic nanoparticles may be from about 20 emu / g to about 100 emu, such as from about 40 emu / g to about 80 emu / g, or from about 50 emu / g to about 70 emu / g, although the total may be out of the ranges below. may have a residual magnetism of / g.

 The coercivity of the magnetic nanoparticles may range from about 200 erstats, such as, for example, from about 1,000 erstats to about 40,000 erstats, or from about 10,000 erstats to about 20,000 erstats, although the total may be out of the range below. About 50,000 erstats.

Magnetic saturation moments may range from about 20 emu / g to about 30 emu / g to about 100 emu / g, or from about 50 emu / g to about 80 emu / g, although the total may be outside the range below. About 150 emu / g.

According to the present invention, there is provided a MICR inkjet ink comprising stabilized magnetic single crystal nanoparticles.

Examples of suitable magnetic nanoparticle compositions with large magnetic crystalline anisotropy (K1) are shown in Table 1. Table 1 also shows the reference magnetite. It should be noted that the actual coercivity obtained for the nanocrystalline particles may be less than the maximum coercivity shown in Table 1 because the coercivity is strongly size dependent. Peak coercive force for Fe and Co occurs when the particle is about 20 nm in size, and peak coercive force for CoO.Fe ₂ O ₃ occurs when the particle is about 30 nm in size. Other suitable magnetic materials with high magnetic crystal anisotropy include CoPt with a K1 value of, for example, 4.9 x 10 ⁶ J / m 3.

Self-crystalline Anisotropy (10 ⁴ J / m ³ ) Maximum coercive force (ersted) MICR Toner Requirements ≥2 ≥300 Reference magnetite ²
(Fe3O4 or FeO · Fe ₂ O ₃ ) 1.1 460 FePt (heart side room grid) ^{Reference 3} 6603 ≥9000 Fe (Cubic) ^{Reference 2} 4 1000 Co ^reference2 40 2100 CoOFe ₂ O ₃ ^{Reference 2} 25 4200 BaO, 6Fe ₂ O ₃ ^{Reference 2} 33 4500 MnAl ^{Reference 2} 100 6000 MnBi ^{Reference 2} 116 12000

Reference 2: F.E. Luborsky, J. Appl. Phys., Supp. to Vol. 32 (3), 171S-184S (1961) and referenced herein

Reference 3: V. Tzitzios et al., Adv. Mater. 17, 2188-92 (2005)

Examples of magnetic nanoparticles with high magnetic crystal anisotropy prepared in the literature are shown in Table 2. Any of the particles shown below are suitable for MICR ink applications.

Particle Chemistry (Crystal Structure) Size (nm) Saturation Moment (emu / g) Residual magnetic moment (emu / g) Coercivity
(Erstat) Magnetic crystal anisotropy
(10 ⁴ J / m ³ ) MICR Toner Condition 10 to 330 No specific requirement > 20 ≥ 300 ≥ 2 FePt
(Face-centered grid) ⁴ 8 cube > 40 30 30,000 660 FePt
(Face-centered grid) ⁴ 15 cube > 50 40 20,000 660 Fe
(Centered cubic grid) ^{Reference 1} 20 x 20 x 200 145 72.7 1540 4.8 ^{Reference 2}

fct = facet square lattice crystal structure; bcc = body-centered cubic crystal structure

Reference 1: F. Watari et al., J. Mater. Sci., 23, pp. 1260-64 (1988).

Reference 4: K. Elkins, et al., J. Phys. D. Appl. Phys., 38, pp. 2306-09 (2005).

Nevertheless, the large intrinsic magnetic crystal anisotropy of the material does not guarantee that the material will have a large residual magnetism or large coercive force to make the material suitable for MICR applications. Similarly, the FePt alloy, Fe or Co, does not have the necessary residual magnetism or coercive force. Certain materials generally only have a material with both single crystal domains of 1) large intrinsic magnetic crystal anisotropy, and 2) domain size of at least about 10 nm (the exact minimum size limit depends on the material). It is generally only suitable for MICR applications.

In addition, it is possible to provide an ink containing binary metal magnetic nanoparticles, wherein the absolute value K1 of the self-crystallization anisotropy of the binary metal magnetic nanoparticles is greater than 2 × 10 ⁴ J / m 3, and FeCo or At least one of Fe ₂ O ₃ . This can be accomplished by any conventionally known talk. For example, an ink containing nanoparticles of FePt crystal structure may be mixed with an ink containing Fe ₂ O ₃ . Alternatively, nanoparticles of FePt crystal structure and Fe ₂ O ₃ may be added into the ink during ink synthesis. Therefore, this mixture combines relatively inexpensive Fe ₂ O ₃ with nanoparticles of FePt crystal structure with improved magnetic and dispersing properties to produce MICR inkjet inks. In such mixtures, the ratio of magnetic nanoparticles to FeCo or Fe ₂ O ₃ is about 0.1: 99.9 or vice versa, such as about 10:90, or about 30:70, or about 50:50. For these mixtures, the loading conditions are about 0.5 wt% to about 15 wt%, such as, for example, about 2 wt% to about 10 wt%, or about 5 wt% to about 8 wt% of the ink, although the total is outside the following range.

The ink composition also includes a carrier material, or a mixture of two or more carrier materials. For example, the water soluble inkjet ink composition may use water or a mixture of water and one or more other solvents as a suitable carrier material.

In the case of a solid (or phase change) inkjet ink composition, the carrier may comprise one or more organic compounds.

In the case of radiation (such as ultraviolet) curable ink compositions, the ink composition typically comprises a carrier material which is a curable monomer, curable oligomer, or curable polymer, or mixtures thereof.

The ink composition according to the present invention may also comprise one or more binder resins.

The binder resin can be any suitable agent.

MICR inks according to the invention can be prepared as colored inks by adding colorants during ink preparation. Any necessary or effective colorant may be employed in the ink composition, including dyes, paints, mixtures of dyes and paints, mixtures of dyes, mixtures of paints, and the like.

One or more waxes may be added to the MICR inkjet ink to increase image density and effectively prevent offsets to reading heads and image smearing.

The ink composition may also optionally contain an antioxidant.

The ink composition may also optionally contain a viscosity modifier.

Other optional additives to the ink include purifiers, tackifiers, adhesives, and plasticizers. Surfactants can be used in the ink.

The ink composition of the present invention may be prepared by any necessary or suitable method.

The MICR ink according to the present invention may be, for example, a water soluble ink, an oil ink, a curable ink, a solid ink or a hot-melt ink.

Magnetic metal particle inks can generally be printed on a suitable substrate.

In order to print MICR ink on a substrate, any suitable printing method can be used.

The inks of the present invention can be used in both MICR and non-MICR applications.

Triamide resin (prepared as described in Example II of US Pat. No. 6,860,930) was processed through a blender to form a powder. About 750.72 g of powdered triamide resin and about 239.7 g of Nipex® 150 carbon black (obtained from Degussa Canada, Burlington, Ontario) were mixed in a LITTLEFORD M5 mixer at 0.8 A for about 30 minutes. The powder mixture was added to the DAVO counter-rotating twin screw extruder (Model VS 104 from Deutsche Apparate-Vertrieborganisation GmbH & Co., Troytov, Germany) at a rate of 0.8 pounds per hour. The contents of the extruder were then mixed at 50 RPM at 70 ° C. The extruded dispersant (Extrudate A) was melt mixed with other ink components to form a carbon black ink as described in Examples 2-5.

Extrusions described in Example 1 (A, 13.13 wt% of total ink weight, about 19.70 g) and petroleum CA-11 diurethane dispersant, 3.95 wt% of total ink weight, about 5.92 g ) Was weighted into the first 250 ml beaker (A). Kemamide® S180 from Crompton Corp. (15.19 wt% of total ink weight, 22.79 g), KE100 resin from Arakawa Chemical Industries Ltd. (10.85 wt% of total ink weight, approximately 16.28 g), and Naugard® N445 from Crompton Corp. (0.12 wt% of total ink weight, about 0.18 g) was added to the second 250 ml beaker B. Polyethylene wax from Baker Petrolite (54.26 wt% of the total ink weight, about 81.39 g), and the urethane resin described in Example 4 of US Pat. No. 6,309,453, incorporated herein by reference in its entirety (2.5 wt. %, About 3.74 g) was added to the third 250 ml beaker (C). Beakers (A, B and C) were heated at 130 ° C. for approximately 3 hours. After 2 hours of heating, the components in the beaker B were stirred with a heated spatula to help melt and dissolve the mixture, which was repeated after 30 minutes. Once the mixture in the beaker (B) was completely dissolved and melted, the contents in the beaker (B) were poured into the beaker (A).

The ultrasonic mill model 500 Sonifier was used to sonify the contents of the beaker A for six times at intervals of 30 seconds each, thus creating a three minute total sonification process time. During sonication, the beaker was rotated to ensure an even treatment throughout the mixture at a temperature maintained below 130 ° C. After the first three minutes of sonication, the beaker A was heated to 110 ° C. for 30 minutes. The sonication treatment was then repeated in beaker A more than once, and the contents in beaker C were gradually poured into beaker A over the first 30 seconds of sonication interval of the third sonication round. Therefore, the prepared carbon black ink showed a viscosity of about 10.8 centipoise (cps) as measured by the TA 2000 AR2000 rheometer. The ink was then filtered through a 1 μm glass fiber disk filter and a 0.45 μm glass fiber disk filter at 110 ° C. with the application of a pressure of 15 psi. The final ink was then cooled to room temperature and tested on a Xerox® PHASER® 8400 piezoelectric inkjet printer. The composition of such inks is described in Table 3 below.

Carbon black inks were prepared as described in Example 2 except that WB-5 polyurethane dispersant (manufactured by Baker Petrolite) was used in place of Petrolite CA-11 (manufactured by Baker Petrolite). The composition of such inks is described in Table 3 below.

Carbon black inks were prepared as described in Example 2 except that WB-17 polyurethane dispersant (manufactured by Baker Petrolite) was used in place of Petrolite CA-11. The composition of such inks is described in Table 3 below.

The following components are melted and stirred-mixed in a 4 L beaker (A) at 125 ° C .: Extruded molding prepared as described in Example 1 (A, 13.13 wt% of total ink weight, about 367.64 g), Petrolite CA-11 (3.94 wt% of total ink weight, about 110.49 g), Kemamide® S180 from Crompton Corp. (15.19 wt% of total ink weight, about 425.41 g), KE100 resin from Arakawa Chemical Industries Ltd. (10.85 wt of total ink weight) %, About 303.86 g), and Naugard® N445 from Crompton Corp. (0.12 wt% of total ink weight, about 3.40 g). Beaker A was equipped with a heating stove and a mechanical stirrer. The carbon black dispersant was heated and stirred at 125 ° C. for 1 hour. In a second 4L beaker (B), distilled polyethylene wax of Baker Petrolite (2.53 wt% of the total weight of the ink, about 70.80 g, as described in US Patent Publication No. 2007/0120916, incorporated herein by reference) This was melt-mixed at 125 ° C. Beaker B was also equipped with a heating stove and a mechanical stirrer. The resin dispersant in the beaker (B) was heated and stirred for 1 hour to ensure that all the resins were completely heat-mixed.

An IKA Ultra Turrax® T50 homogenizer was used to homogenize the components in the beaker (A) for 30 minutes at 125 ° C. The molten resin mixture in the beaker (B) maintained at 125 ° C. was added into the homogenized dye dispersant in the beaker (A). The carbon black ink in the beaker A became more homogenous for an additional 30 minutes. The rheology of the carbon black ink in the beaker (A) was measured using an AR2000 flow meter. The resulting carbon black ink was filtered at 115 ° C. through a 1 μm glass fiber cartridge-filter and then through a 0.45 μm glass fiber cartridge-filter under low pressure (less than 5 psi). The ink was then cooled to room temperature. The final ink was tested on a Xerox® Phaser 8860 piezo inkjet printer.

Magnetic Fe particles are prepared according to the procedures described in aterials Science, 23, 1260-1264 (1988), by Watari et al., Which is hereby incorporated by reference in its entirety. Mineral goethite α-FeOOH with a 0.5 μm particle size is described by Luborsky, J. Appl. Phys, Supplement to Vol. 32 (3), an aspect ratio of 10/1, a residual magnetic moment of 72.2 emu / g, a coercive force of 1540 erstats, and a magnetic crystal of about 4 x 10 ⁴ J / m ³ , as measured by 171S-184S (1961) It was reduced under isothermal heat treatment at 400 ° C. in a hydrogen atmosphere for 2 hours to convert the particles into Fe metal particles of 20 × 20 × 200 nm size with anisotropy.

Magnetic FePt particles are prepared according to the procedure described in Li et al. Journal of Applied Physics 99, 08E911 (2006). 15 nm FePt nanoparticles are chemically synthesized in an argon atmosphere. The x-ray crystal structure of FePt is fcc. NaCl powder is ball milled for 24 hours. The ball milled NaCl powder is then dispersed in hexane and mixed with the hexane dispersion of as-synthesized body centered cubic FePt nanoparticles, so that the ratio of NaCl to FePt is 100: 1. The mixture is stirred until all solvents evaporate and annealed in forming gas (93% H ₂ and 7% Ar) at 700 ° C. for 2 hours to convert FePt to the required facet square lattice crystal structure. The salt is washed with water and the particles are dried. Magnetic Fe particles are cubes having a size of 15 nm, an aspect ratio of 1/1, a residual magnetic moment of about 40 emu / g, and a coercive force of 20,000 Erstets, and magnetic crystal anisotropy of 660 × 10 ⁴ J / m ³ .

In addition to adding 71.91 g of magnetic Fe particles A prepared as described in Example 6, to form an extrusion (B), the steps described in Example 1 are performed.

The steps described in Example 8 are performed in addition to using about 200.00 g of magnetic Fe particles (A) as described in Example 6 instead of 71.91 g.

The extrudates prepared as described in Example 8 (B, 13.13 wt% of the total ink weight, about 19.70 g) and the Petrolite CA-11 polyurethane dispersant (3.95 wt% of the total ink weight, about 5.92 g) were first 250 Weighted in ml beakers (A). Kemamide® S180 from Crompton Corp. (15.19 wt% of total ink weight, about 22.79 g), KE100 resin from Arakawa Chemical Industries Ltd. (10.85 wt% of total ink weight, about 16.28 g), and Naugard® from Crompton Corp. N445 (0.12 wt% of total ink weight, about 0.18 g) is weighted to the second 250 ml beaker B. Polyethylene wax from Baker Petrolite (54.26 wt% of the total ink weight, about 81.39 g), and the urethane resin (2.5 wt% of the total ink weight, about 3.74 g) described in Example 4 of US Pat. It is weighted to the beaker C. Beakers A, B and C are heated at 130 ° C. for approximately 3 hours. After 2 hours of heating, the composition in the beaker B is stirred with a heating spatula to help melt and dissolve the mixture, which is repeated after 30 minutes. Once the mixture in beaker B is completely dissolved and melted, the contents in beaker B are poured into beaker A.

Therefore, the prepared magnetic carbon black ink shows a projected viscosity of about 11 as measured on an TA 2000 rheometer from TA Instruments. This viscosity is only evaluated from the viscosity of the ink containing carbon black, and the viscosity of the carbon black is typically in the range of about 10 to 11 cps at about 110 to about 140 ° C. Once the Fe particles are well dispersed, the particles are not expected to increase to a viscosity of from about 10 or more to about 20% depending on the concentration of the Fe particles. The ink is then filtered through 6 μm and then optionally 1.0 μm glass fiber disc filters at 110 ° C. with application of a pressure of 15 psi in succession. The final ink is cooled to room temperature and printed. The composition of such inks is described in Table 3 below.

The following components are melted and stirred-mixed in a 4 L beaker (A) at 125 ° C .: Extruded molding prepared as described in Example 9 (C, 13.13 wt% of total ink weight, about 367.64 g), Petrolite CA-11 (3.94 wt% of total ink weight, about 110.49 g), Kemamide® S180 from Crompton Corp. (15.19 wt% of total ink weight, about 425.41 g), KE100 resin from Arakawa Chemical Industries Ltd. (10.85 wt of total ink weight) %, About 303.86 g), and Naugard® N445 from Crompton Corp. (0.12 wt% of total ink weight, about 3.40 g). Beaker A is equipped with a heating stove and a mechanical stirrer. Magnetite containing carbon black dispersant is heated and stirred at 125 ° C. for 1 hour. In a 4 l beaker (B), a urethane as described in example 4 of US Pat. No. 6,309,453, incorporated herein by reference in its entirety (54.24 wt%, about 1,519.32 g of the total ink weight) by Baker Petrolite The resin (2.53 wt% of the total ink weight, about 70.80 g) is melt mixed at 125 ° C. Beaker B is also equipped with a heating stove and a mechanical stirrer. The resin dispersant in the beaker B is heated and stirred for 1 hour to ensure that all the resin is completely melt mixed.

An IKA Ultra Turrax® T50 homogenizer is used to homogenize the components in the beaker (A) for 30 minutes and the temperature is maintained at 125 ° C. during homogenization. The molten resin mixture in beaker B maintained at 125 ° C. is then added into the homogenized dye dispersant in beaker A. The magnetic carbon black ink in the beaker A is further homogenized for an additional 30 minutes. After filtering the resulting ink through 6 μm and then 1.0 μm glass fiber filter at 115 ° C. under low pressure (less than 5 psi), the ink is cooled to room temperature. The final ink is then printed using an inkjet printer. The composition of such inks is described in Table 3 below.

Magnetic carbon black ink was prepared as described in Example 11 except that the extrudate (C) was added to the ink after the last 30 minutes of homogenization step, and the ink was homogenized for an additional 20 minutes. The composition of such inks is described in Table 3 below.

The steps described in Example 8 are performed in addition to that 71.91 g of magnetic FePt particles (B) of Example 7 are used in place of 71.91 g of magnetic Fe particles (A) of Example 6.

The extrusion molding prepared as described in Example 13 (D, 13.13 wt% of the total ink weight, about 19.70 g) and Petrolite CA-11 (3.95 wt% of the total ink weight, about 5.92 g) were made of the 250 ml beaker (A Weighted). Kemamide® S180 from Crompton Corp. (15.19 wt% of total ink weight, about 22.79 g), KE100 resin from Arakawa Chemical Industries Ltd. (10.85 wt% of total ink weight, about 16.28 g), and Naugard® from Crompton Corp. N445 (0.12 wt% of total ink weight, about 0.18 g) is weighted to the second 250 ml beaker B. Polyethylene wax from Baker Petrolite (54.26 wt% of the total ink weight, about 81.39 g), and the urethane resin described in Example 4 of US Pat. No. 6,309,453, incorporated herein by reference in its entirety (2.5 wt% of the total ink weight). , About 3.74 g) is weighted to the third 250 ml beaker (C). Beakers A, B and C are heated to 115 ° C. for approximately 3 hours. After 2 hours of heating, the composition in the beaker B is stirred with a heating spatula to help melt and dissolve the mixture, which is repeated after 30 minutes. Once the mixture in beaker B is completely dissolved and melted, the contents in beaker B are poured into beaker A.

Therefore, the prepared magnetic carbon black ink is expected to exhibit a viscosity of about 11 cps at about 110 ° C. to about 140 ° C. as measured on an TA 2000 rheometer from TA Instruments. The ink is then filtered continuously through 6 μm and then 1.0 μm fiberglass disc filter at 110 ° C. with the application of a pressure of 15 psi. The composition of such inks is described in Table 3 below.

In addition to the WB-5 dispersant being used in place of Petrolite CA-11, magnetic carbon black inks were prepared as described in Example 12. The composition of such inks is described in Table 3 below.

In addition to the WB-17 dispersant being used in place of Petrolite CA-11, magnetic carbon black inks were prepared as described in Example 12. The composition of such inks is described in Table 3 below.

The steps described in Example 8 are performed in addition to using about 200.00 g of magnetic FePt particles (B) prepared as described in Example 7 in place of 71.91 g of magnetic Fe particles (A) prepared as described in Example 6 .

Carbon black ink is prepared as described in Example 12 using an extrudate prepared as described in Example 17 (instead of E, Extrusion (C) prepared as described in Example 9). The composition of such inks is described in Table 3 below.

Carbon black ink is semi-empty as described in Example 14 except that WB-5 dispersant was used in place of Petrolite CA-11 E. The composition of such inks is described in Table 3 below.

Carbon black inks are prepared as described in Example 14 except that WB-17 dispersant was used in place of Petrolite CA-11. The composition of such inks is described in Table 3 below.

39.9 g of magnetic FePt particles prepared as described in Example 7 were subjected to ball milling for 3 hours with 83 g of Nipex® 150 carbon black (manufactured by Degussa Canada, Burlington, Canada) solution added to make a dye dispersant. Is added to 300 g of deionized water containing 1.3 g of 20% water soluble anionic surfactant Dowfax 2A1 ™.

The water-soluble ink composition comprises 15.25 g of diethylene glycol, 5.0 g of Jeffamine ED-600, polyether diamine (manufactured by Texaco Chemical Co.), and 20.15 g of prepared dye dispersant in 59.6 g of deionized water. It is prepared by adding and mixing.

Control ink Ink composition
Component (wt% of total ink weight) 2 3 4 5 10 11 12 14 15 16 18 19 20 Triamide resin 9.95 10.3 10.26 9.95 9.28 8.28 11.92 9.28 9.28 9.28 11.92 9.28 9.28 Nipex® 150 Carbon Black 3.18 3.06 3.05 3.18 2.96 2.64 3.81 2.96 2.96 2.96 3.81 2.96 2.96 Urethane induction
Petrolite CA-11 ™ 3.95 0 0 3.94 3.95 3.94 3.68 3.95 0 0 3.68 0 0 Urethane induction
WB-5 ™ 0 2.64 0 0 0 0 0 0 2.87 0 0 2.87 0 Urethane induction
WB-17 ™ 0 0 2.63 0 0 0 0 0 0 2.82 0 0 2.82 Kemamide ™ S180 15.19 15.25 15.4 15.19 15.19 15.19 14.18 15.19 15.25 15.4 14.18 15.25 15.4 KE100 ™ Resin 10.85 10.89 11 10.85 10.85 10.85 10.13 10.85 10.89 11 10.13 10.89 11  Naugard® N445 0.12 0.12 0.13 0.12 0.12 0.12 0.11 0.12 0.12 0.12 0.11 0.12 0.12 Polyethylene wax 54.26 55.2 55 54.24 54.26 54.24 50.63 54.26 55.2 55 50.63 55.2 55 Urethane resin 2.5 2.54 2.53 2.53 2.5 2.53 2.36 2.5 2.54 2.53 2.36 2.54 2.53 Magnetite Dye A 0 0 0 0 0.89 2.21 3.18 0 0.89 0.89 0 0 0 Magnetite Dye B 0.89 3.18 0.89 0.89 Sum 100 100 100 100 100 100 100 100 100 100 100 100 100 After filtration at 110 ° C., the viscosity, cPs, 10.76
10.45
10.66
11.1
Although not tested, predicted about 10.5 to 14 at about 110 ° C. to about 140 ° C.

A stable magnetic carbon black concentrate in dibutyl sebacate (manufactured by Morflex Inc., NC) is obtained as follows: 40 mm classic between an initial rate of 1500 RPM and a final rate of 2500 RPM. 60.0 g Nipex® carbon black (manufactured by Cabot) in a 1 liter, stainless steel beaker attached to a DISPERMAT FT (manufactured by VMA-Getzmann GMBH) equipped with a set of high-shear mixed dissolution devices ) Is slowly added to a solution of 100 g of SOLSPERSE 13940 (40% active, manufactured by Avecia) in 100.18 g of dibutyl sebacinate (manufactured by Morflex Inc.). 40 g of magnetic Fe particles (A) prepared as described in Example 6 were added. The dispersant is continuously stirred for 2 hours after the addition of carbon black and magnetic particles. The loading of the dispersant on the dye is estimated to be about 2.6 mg / m 2, providing optimal conditions for stability.

This dispersion is further processed for 270 minutes in DISPERMAT SL-C 12 (manufactured by VMA-Getzmann GMBH) under the following conditions: rate = 2000 RPM; Temperature = 30-55 ° C. (cooled water); Circulation rate = ˜3 g / s through 125 mL chamber; Amount of milling beads = 100 ml; Morphology of beads = 0.8-1.0 zirconium-silicon dioxide.

Cobalt salts of Linolenic Acid can be prepared as described in Example 5 of US Patent Publication No. 2007 / 0120923A1.

Cobalt salts of linolenic acid can be obtained by direct electrochemical synthesis as described by Kumar et al in the Canadian Journal of Chemistry (1987), 65 (4), 740-3. In particular, 0.1 g of linolenic acid is dissolved in 50 ml of acetone containing 0.04 g of Et ₂ NC10 ₄ . This solution is added to prepare a simple electrochemical cell in form Pt ⁽⁻⁾ / CH ₃ CN + linolenic acid / Co ⁽⁺⁺⁾ and an initial voltage of 25V is applied for 45 minutes. Cobalt (II) linolenic acid salts precipitate directly during electrochemical oxidation.

Alternatively, the cobalt salt of linolenic acid may be prepared by precipitation treatment, such as adding water soluble cobalt sulphate to the hot sodium salt solution of linolenic acid with stirring until the precipitation is complete. The resulting salt is washed and dried by conventional methods. Cobalt salts of linolenic acid can be obtained simply by this method.

Ink compositions 24-27 containing magnetic particles were prepared in a high shear mixer to disperse a stable carbon black concentrate prepared as described in Example 22 in a mixture of linear and branched alcanes with alcohol in a vehicle. Then, it is prepared to add a metal salt. Table 4 sets the specific composition of Example 24-27. Alternatively the metal salt may be manganese stearate.

Yes media Metal salt coloring agent Linear alkanes Branched alkanes Alcohol shape Wt% of total ink weight shape Wt% of total ink weight shape Wt% of total ink weight shape Wt% of total ink weight shape Wt% of total ink weight 24 n-hexadecane (Aldrich) 20 ISOPAR V (EXXON) 47 Oleyl Alcohol (Sigma Aldrich) 20 ADDITOL VXW 6206 (Solutia Inc.) 3 Example 22 10 25 NORPAR 15 (EXXON) 27.5 ISOPAR V (EXXON) 39.5 Oleyl Alcohol (Sigma Aldrich) 20 ADDITOL VXW 6206 (Solutia Inc.) 3 Example 22 12 26 NORPAR 15 (EXXON) 12 ISOPAR L (EXXON) 56 Oleyl Alcohol (Sigma Aldrich) 25 Cobalt salt of linolenic acid
(Example 23) 2 Example 22 5 27 n-hexadecane (Aldrich) SHELLSOL T (Shell) Oleyl Alcohol (Sigma Aldrich) 24 Cobalt salt of linolenic acid
(Example 23) 2 Example 22 7

Claims (1)

carrier; Optional colorants; And Includes stabilized magnetic single crystal nanoparticles, The magnetic anisotropy absolute value of the magnetic nanoparticles is 2 x 10 ⁴ J / ㎥ or more ink.