KR20200044549A - Security ink composition comprising AlNiCo based magnetic particle - Google Patents

Abstract

The present invention relates to a security ink composition comprising AlNiCo-based magnetic particles with ultrafine particles of a D50 of 12 μm or less, having uniform magnetic properties for each particle due to remarkably small composition variation, implementing a highly secure element, having pale color properties which can conceal dark colored magnetic particles, having enhanced security which can be distinguished from hard magnetic materials only with expensive recognition equipment, and having an aptitude for printing, thereby being suitable for an ink of various conventional uses.

Description

Security ink composition comprising AlNiCo based magnetic particles

The present invention relates to a security ink composition comprising AlNiCo-based magnetic particles.

Security materials can be said to be essential in areas where anti-counterfeiting is needed. For example, in the secure printing field, a security material is used for oil prices such as checks, stamps, gift certificates, vouchers, and bonds.

Currently, magnetic particles having a core shell structure formed by coating an inorganic substance with a magnetic substance are known, and an inorganic substance is coated to brighten the dark color of the magnetic substance, or another kind of inorganic substance is further coated to improve the mechanical properties of the magnetic particle It is known to do (Korean Patent Publication No. 2013-0072444).

Recently, research has been attempted to maximize the security of security products using security materials. As a first step of the study, a method in which the coercive force and the magnetization density of the magnetic particles are located in a specific region, and more specifically, by mixing ferromagnetic particles having a relatively large coercive force and soft magnetic particles having a relatively low coercive force, When formed in a pattern, the possibility of maximizing the security of a security product was suggested.

However, due to the evolution of highly developed measuring equipment, if the security material has a simple pattern, or if the coercive force difference between the magnetic particles incorporated is too large, it can be easily recognized from general equipment. It is required to have a coercive force and a magnetization density of a specific window so that it can be recognized only as "expensive recognition equipment".

However, the existing magnetic particles solve the problem, but the following problems still exist. 1) If the magnetization density of the magnetic particles is too large or too small, expensive recognition equipment has difficulty in measuring the unique signal of the magnetic particles. 2) If the size of the magnetic particles is too large or small, the magnetic particles are difficult to effectively reflect sunlight, making it difficult to cover up the dark colored magnetic particles, and the security is sharply reduced. During the process, it may cause problems such as poor printing.

As a solution to this problem, i) a method of manufacturing relatively small nanoparticles by agglomerating with a binder, and ii) a method of crushing relatively large particles to a desired size may be presented.

However, the method of aggregating a binder of i) is difficult to manufacture with magnetic particles for security having a specific size and a specific shape because a problem of swelling of the binder may occur when agglomerating with the magnetic particles.

The crushing method of ii) may be advantageous in terms of coercive force, magnetization density, purity, cost, etc. since a binder is not added compared to the binder agglomeration method of i).

However, the grinding method of ii) is generally produced by the Crush method, and the Crush method was found to be difficult to control the particle size at the level of several micros. In addition, the powder starting from a relatively large coercive force as a starting material has a phenomenon in that the coercive force is greatly reduced as the size becomes smaller.

In addition to these two methods, an atomizing method is known as a method of manufacturing magnetic particles in a specific size. The atomizing method is classified into a gas spraying method, a water spraying method and a mixed spraying method according to the type of the cooling medium. In general, the atomizing method sprays a molten metal of an alloy into a cooling medium through a nozzle or the like, thereby colliding the molten metal with the cooling medium to cool the droplets of the molten metal, through which the fine magnetic particles having a particle size of tens or hundreds of μm are obtained. Manufacturing is possible.

However, since the water atomization process uses water (H ₂ O) as the main cooling medium, the oxidation problem of the powder to be manufactured is large.

In addition, since the gas spraying method uses inert gas (N ₂ , Ar, He) or air as a cooling medium, it is possible to manufacture high-quality powder due to less problems of oxidation and impurities mixing during powder production, but the cooling effect is relatively There is a concern that micro segregation may occur during the manufacturing process due to the low, technical difficulties in manufacturing magnetic particles of a specific shape, and the yield is very low, around 5%, leading to very poor commerciality.

Accordingly, the applicant has provided a technique for producing AlNiCo-based magnetic particles having printability while having magnetic properties that can operate as a strong security element while effectively reflecting sunlight and concealing dark colored magnetic particles ( Republic of Korea Registered Patent No. 1718505), as a result of continuing the related studies in more depth, has achieved an improved yield, and improved security, the manufacturing technology of AlNiCo-based magnetic particles has been established, leading to the application of the present invention.

Republic of Korea Patent Publication No. 2013-0072444 Republic of Korea Registered Patent No. 1718505

An object of the present invention is to provide a security ink composition comprising AlNiCo-based magnetic particles having improved security.

In detail, the present invention has magnetic properties that can be distinguished from paramagnetic particles by expensive recognition equipment, has bright colors, has excellent printability, and has a designed composition and an extremely uniform composition, and secures fine linearity. The pattern is also to provide a security ink composition containing AlNiCo-based magnetic particles that can be stably formed.

Another object of the present invention is to provide a security ink composition having high viscosity, uniform elasticity, and high durability, while significantly improving security properties.

The security ink composition according to the present invention is a security ink composition comprising AlNiCo-based magnetic particles, varnish, pigment, surfactant, wax and solvent, wherein the AlNiCo-based magnetic particles include Al, Ni and Co core particles; And an inorganic shell surrounding the core particles, wherein the core particles are ultrafine particles having a particle size of D ₅₀ equal to or less than ₅₀ μm in a cumulative distribution of particle diameters of 12 μm or less. , Equations 2 and 3 have compositional uniformity.

Equation 1: 10 ≤ UNF (Al)

Equation 2: 10 ≤ UNF (Ni)

Equation 3: 10 ≤ UNF (Co)

In Equation 1, UNF (Al) is a weight percent composition basis, the average Al composition between core particles divided by the standard deviation of the Al composition, and in Equation 2, UNF (Ni) is a weight percent composition basis and the average Ni composition between core particles. It is the value divided by the standard deviation of the Ni composition, and UNF (Co) in Equation 3 is the weight% composition standard, and the average Co composition between core particles divided by the standard deviation of the Co composition.

Security ink composition according to an embodiment of the present invention is 5 to 15% by weight of the AlNiCo-based magnetic particles, 10 to 40% by weight of the varnish, 30 to 70% by weight of the pigment, 1 to 20% by weight of the surfactant, the wax 1 To 15% by weight and 1 to 30% by weight of the solvent.

In one example of the present invention, the varnish may include any one or two or more selected from thermoplastic resins, thermosetting resins and photocurable resins.

In one example of the present invention, the pigment is a soluble azo pigment, an insoluble azo pigment, a phthalocyanine pigment, a halogenated phthalocyanine pigment, a quinacridone pigment, an isoindolinone pigment, an isoindolin pigment, a perylene pigment, a perinone pigment, Dioxazine pigment, anthraquinone pigment, dianthraquinonyl pigment, anthrapyrimidine pigment, andandron pigment, indanthrone pigment, flavantron pigment, pyranthrone pigment, and diketopyrrolopyrrole pigment, etc. It can contain.

In one example of the present invention, the surfactant includes any one or two or more selected from fluorinated surfactants, polymerizable fluorinated surfactants, siloxane surfactants, polymerizable siloxane surfactants, polyoxyethylene surfactants, and derivatives thereof can do.

In one example of the present invention, the wax may include any one or two or more selected from polyethylene wax, amide wax, erucamide wax, polypropylene wax, paraffin wax, Teflon, and carnauba wax.

In one example of the present invention, the AlNiCo-based magnetic particles may be manufactured by an atomizing method using a refrigerant containing at least water.

In one example of the present invention, the following formulas 4, 5, and 6 may be satisfied based on a design composition that is a composition of an alloy molten metal containing Al, Ni, and Co used in atomizing.

Equation 4:

Equation 5:

Equation 6:

In the above formulas 4 to 6, C _m (Al) is based on weight percent composition, average Al composition between core particles, C ₀ (Al) is based on weight percent composition, Al composition of design composition, C _m (Ni) is Based on weight percent composition, average Ni composition between core particles, C ₀ (Ni) is based on weight percent composition, Ni composition of design composition, C _m (Co) is based on weight percent composition, average Co composition between core particles , C ₀ (Co) is the Co composition of the design composition, based on weight percent composition.

Security ink composition according to an embodiment of the present invention may satisfy the following equations 7 and 8.

Equation 7: 3 μm ≤ D ₅₀ ≤ 12 μm

Equation 8: 10 μm ≤ D ₉₀ ≤ 20 μm

In Equation 7, D ₅₀ is a particle size corresponding to 50% in the cumulative distribution of particle diameters, and in Equation 8, D ₉₀ is a particle size corresponding to 90% in the cumulative distribution of particle diameters.

In one example of the present invention, the hard magnetic particles may have an L * value measured by a color difference meter of 60 or more.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the inorganic shell includes a metal shell, and the metal shell may satisfy Equations 6 and 7 below.

Equation 9: 50 nm ≤ t _m ≤ 100 nm

Equation 10: σ _t ≤ 30 nm

In equation 9, t _m is the average thickness of the metal shell, and in equation 10, σ _t is the standard deviation of the metal shell thickness.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the inorganic shell may further include a dielectric shell located below or above the metal shell.

In one example of the present invention, the dielectric shell may be located under the metal shell, and the metal shell may include any one or two or more selected from copper, nickel, gold, platinum, silver, aluminum and chromium. The dielectric shell may include any one or two or more selected from titanium oxide, silicon oxide, aluminum oxide, zinc oxide, zirconium oxide, calcium carbonate, magnesium fluoride and zinc sulfide.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the saturation magnetization (Ms) of the magnetic particles is 50 to 150 emu / g, and the residual magnetization (Mr) is 10 to 40 emu / g day You can.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the coercive force of the magnetic particles may be 100 to 500 Oe.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the core particles may further include one or two or more fourth elements selected from Cu, Ti, Fe and Si.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the core particles have a weight-based composition standard, and the value obtained by dividing the average fourth element composition between core particles by the standard deviation of the fourth element composition is 10 or more. You can.

In the AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention, the core particles further contain Ti, Fe, and Cu, based on weight percent, Al 4 to 12%, Ni 10 to 20%, Co 15 to 25%, Ti to 1 to 10%, Cu to 0.5 to 5%, balance Fe and other unavoidable impurities.

AlNiCo-based magnetic particles (I, II) according to an embodiment of the present invention may have an infrared reflectance of 60% or more based on a 900 nm wavelength.

Security ink composition according to an embodiment of the present invention may be used for printing intaglio ink.

The present invention may include a price tag including AlNiCo-based magnetic particles described above, which may be printed with the security ink composition.

The security ink composition according to the present invention has the effect that the AlNiCo-based magnetic particles for security are ultra-fine particles having a D ₅₀ of 12 μm or less, and have a strictly designed composition, thereby improving security.

The security ink composition according to the present invention, while the AlNiCo-based magnetic particles for security according to the present invention are ultra-fine particles having a D ₅₀ of 12 μm or less, the composition deviation is remarkably small, and can have uniform magnetic properties for each particle. It is possible to implement a security element having a shape of.

Security ink composition comprising AlNiCo-based magnetic particles according to an embodiment of the present invention, AlNiCo-based magnetic particles have a pale color property to conceal magnetic particles of dark color, and are distinguished from hard magnetic bodies only with expensive recognition equipment It has an enhanced security that is recognizable and has printability, so it has an advantage suitable for ink of various conventional uses.

Even if the effects are not explicitly mentioned in the present invention, the effects described in the specification expected by the technical features of the present invention and the inherent effects thereof are treated as described in the specification of the present invention.

1 is a scanning electron microscope photograph of AlNiCo-based magnetic particles prepared according to an embodiment of the present invention,
FIG. 2 is a scanning electron microscope photograph of a cross section of an AlNiCo-based magnetic particle manufactured according to an embodiment of the present invention and a measurement of the thickness distribution of a silver shell.
Figure 3 is an optical image, soft magnetic image, hard magnetic image observing a security element formed of a security ink containing the AlNiCo-based magnetic particles and the general soft magnetic particles prepared according to an embodiment of the present invention and This is a diagram showing an infrared image.

Hereinafter, a security ink composition including AlNiCo-based magnetic particles according to the present invention will be described in detail with reference to the accompanying drawings.

The drawings described in this specification are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention is not limited to the presented drawings and may be embodied in other forms, and the drawings may be exaggerated to clarify the spirit of the present invention.

Unless otherwise defined in the technical terms and scientific terms used in the present specification, those skilled in the art to which the present invention pertains have the meanings commonly understood, and the subject matter of the present invention in the following description and the accompanying drawings. Descriptions of well-known functions and configurations that may unnecessarily obscure are omitted.

As used herein, the singular form of the term may be interpreted as including the plural form unless otherwise specified.

 The units of% used in the present specification without specific mention mean the weight% unless otherwise specified.

In the process of actually manufacturing a security element on a price certificate using fine AlNiCo-based hard magnetic particles having a size of a micrometer order (µm order), the applicant is also an expensive recognition device when designing a security element in a fine linear form. It was confirmed that the paramagnetic particle-based security element and the reproducible security element type were not recognized reproducibly or together. As a result of deepening the research to solve these problems, it was confirmed that in order to stably implement the fine linear security element, it is necessary to suppress the uniform composition properties between AlNiCo-based magnetic particles, that is, to suppress the composition deviation between the manufactured magnetic particles. As a result of conducting a long-term continuous study to secure uniform composition characteristics, the conventional gas injection method (atomizing method using gas as a cooling medium) has an aluminum-rich phase or iron due to a slow cooling rate. -There is a limit that cannot prevent segregation that causes a rich phase (Fe-rich phase), and induces rapid cooling using water as a cooling medium, but elements that are easily oxidized during the cooling process (eg, Al , Ti, etc.) must be prevented, the composition variation is suppressed to have uniform magnetic properties, and it has been confirmed that particles of substantially the same composition as the designed composition are prepared, and thus the present invention has been applied.

The security ink composition according to the present invention includes AlNiCo-based magnetic particles, varnish, pigment, surfactant, wax and solvent. The security ink composition according to the present invention includes AlNiCo-based hard magnetic particles, which will be described later, has excellent printability, has a designed composition and an extremely uniform composition, and can also form a fine linear security pattern stably, high viscosity, uniformity It has the effect of significantly improving the security characteristics while having one elastic force and high durability.

Accordingly, the present invention includes one aspect of the magnetic particle (I) in which composition variation between particles is suppressed, and the designed composition, that is, the magnetic particle (II) having a composition substantially the same as the composition of the molten metal used in atomizing is different. One aspect. In describing the present invention, unless otherwise specifically described one aspect, all of the above descriptions apply to both one aspect (magnetic particles (I)) and another aspect (magnetic particles (II)).

In detailing the present invention, AlNiCo-based may mean an alloy containing Al, Ni, and Co, and AlNiCo-based magnetic particles may mean hard-magnetic alloy particles containing Al, Ni, and Co, and oil prices. It may mean a magnetic particle for security used in the security of. Hard magnetism particles are difficult to magnetize, but once magnetized, it is difficult to demagnetize, which means that the coercive force (Hc) and the residual magnetization density (Mr) are higher than those of the soft magnetism particles. In the AlNiCo-based magnetic particles, hard magnetic properties may mean magnetic properties having a coercive force of 100 to 500 Oe. On the other hand, the soft magnetic particles mean that they can be easily magnetized by a relatively weak magnetic field, and when the external magnetic field is removed, it means that the magnetization rapidly disappears with time. The soft magnetic property may mean a magnetic property having a coercive force of 10 to 90 Oe.

In detailing the present invention, the water-based atomizing method may mean a process or a manufacturing method using a cooling medium containing water when spraying a molten metal of an alloy through a nozzle or the like. At this time, the water-based atomizing method should not be interpreted as being limited to using only water as a cooling medium, and water and gas (eg, inert gases such as N ₂ , Ar, He, Ne, etc.) are simultaneously used as a cooling medium. Should also be construed as including.

In detailing the present invention, the AlNiCo-based magnetic particles may mean a group of magnetic particles, that is, aggregates of individual magnetic particles, and individual magnetic particles independent of each other, excluding aggregates in which magnetic particles are aggregated or aggregates in which core particles are aggregated. It can mean a group of people. At this time, the meaning of the 'group' means at least the number of the degree to which the average magnetic property does not change by the number of magnetic particles forming the 'group'. That is, it may mean a group consisting of magnetic particles having a size (number) or more of a degree that the magnetic properties of the magnetic particle group can be uniformly displayed. In other words, 'group' may mean a group of particles having a size that can be obtained with a reliable average size, average composition, and dispersion value. In the above-described aspect, AlNiCo-based magnetic particles are a group of magnetic particles having at least 50 or more, specifically at least 100 or more, more specifically at least 300 or more, more specifically at least 500 or more, and even more specifically at least 1000 or more. Can mean As a manufacturing method, AlNiCo-based magnetic particles are obtained integrally by atomizing an AlNiCo-based alloy molten metal having a composition designed using a refrigerant containing water, that is, particles (s) obtained integrally in a single water-based spraying method ) As a core particle may mean a group of magnetic particle (s).

The Al-based magnetic particles (I) according to an aspect of the present invention are magnetic particles having a compositional variation between magnetic particles suppressed. Specifically, the AlNiCo-based magnetic particles (I) according to the present invention contain Al, Ni, and Co. Core particles; And an inorganic shell surrounding the core particles, wherein the hard magnetic particles include, the core particles are ultra-fine particles having a particle size D ₅₀ of 12 μm or less in the cumulative distribution of the core particles, and the core particles have the following formula: It has the composition uniformity of 1, Formula 2, and Formula 3.

Equation 1: 10 ≤ UNF (Al)

Equation 2: 10 ≤ UNF (Ni)

Equation 3: 10 ≤ UNF (Co)

In Equation 1, UNF (Al) is a weight percent composition basis, the average Al composition between core particles divided by the standard deviation of the Al composition, and in Equation 2, UNF (Ni) is a weight percent composition basis and the average Ni composition between core particles is Ni It is a value divided by the standard deviation of the composition, and in equation 3, UNF (Co) is the weight percent composition basis, and the average Co composition between core particles is divided by the standard deviation of the Co composition.

That is, UNF (Al) is the standard deviation of the Al composition of the average Al composition (average Al weight%) between the core particles, the standard deviation of the Al weight% between core particles ), UNF (Ni) is the standard deviation of the Ni composition (average Ni weight%) between the average Ni composition (average Ni weight%) between the core particles, based on the weight% composition based on the total weight of the core particles being 100%. % Standard deviation), UNF (Co) is the standard deviation of the core composition (average Co weight%) from the average Co composition (average Co weight%) between the core particles, based on the weight percent composition with the total weight of the core particles being 100%. It is the value divided by the standard deviation of Co weight% between particles).

As described above, the magnetic particles may mean a group of magnetic particles, and in Equations 1, 2, and 3, the average Al composition (or Ni composition or Co composition) of the core particles is the magnetic particles constituting the magnetic particle group. The average value of the Al composition (or Ni composition or Co composition) based on the weight percent of each of the core particles may mean, and the standard deviation of the Al composition (or the standard deviation of the Ni composition or the standard deviation of the Co composition) is magnetic. Of course, it may mean a standard deviation in the Al composition (or Ni composition or Co composition) of each of the core particles of the magnetic particles forming the particle group. Further, in the UNF of any arbitrary element, as the uniformity of the composition increases, as the UNF increases, it is meaningless to limit the upper limit of the UNF, but in practice, the upper limit of the UNF may reach 200.

The composition uniformity of AlNiCo-based magnetic particles satisfying Equations 1, 2 and 3 can be obtained by a conventionally known gas atomization process and a conventional water atomization process in which oxidation by water occurs. The composition uniformity of AlNiCo-based particles that cannot be counted, the average particle is on the order of several micrometers, and it is not distinguished from soft magnetic particles by general recognition equipment, and hard magnetism that can be distinguished from soft magnetic particles by expensive recognition equipment It is composition uniformity not reported in AlNiCo-based magnetic particles having properties.

As described above, the AlNiCo-based magnetic particles according to the present invention, while the core particles are ultrafine particles having a D50 of 12 μm or less, the compositional uniformity, which is the main factor for determining the magnetic uniformity of the AlNiCo-based magnetic particles, is expressed in Equation 1, It is characterized by a collection of magnetic particles having a remarkably low compositional deviation that satisfies Equations 2 and 3, whereby the security element is designed by expensive recognition equipment even when the security element is designed in a fine linear manner. It can be recognized stably and reproducibly without damage, and can be significantly improved by recognizing / recognizing stably even when a fine linear security element is intermingled with a paramagnetic particle-based security element. AlNiCo-based magnetic particles according to a more characteristic and advantageous example may satisfy UNF (Al) of 11 or more, UNF (Ni) of 40 or more, and UNF (Co) of 30 or more. The AlNiCo-based magnetic particles may exhibit highly uniform magnetic properties due to the high composition uniformity.

The magnetic particles according to another aspect of the present invention, together with one aspect described above or independently of the one aspect described above, are magnetic particles (II) having a designed composition, that is, a composition substantially identical to the composition of the molten metal used in atomizing. to be. Specifically, the magnetic particles (II) according to another aspect of the present invention include core particles containing Al, Ni, and Co; And an inorganic shell surrounding the core particles, wherein the hard magnetic particles include, the core particles are ultra-fine particles having a particle size of D ₅₀ equal to or less than ₅₀ μm in a cumulative distribution of particle diameters of 12 μm or less, and the core particles include at least water. It is produced by an atomizing method using a refrigerant containing a, and has a composition satisfying the following equations 4, 5 and 6 based on the design composition, which is a composition of an alloy molten metal containing Al, Ni, and Co used in atomizing.

Equation 4:

Equation 5:

Equation 6:

In Equation 4, C _m (Al) is based on weight percent composition, average Al composition between core particles, C ₀ (Al) is based on weight percent composition, Al composition of design composition, C _m (Ni) is weight percent composition Criteria, average Ni composition between core particles, C ₀ (Ni) is the weight percent composition basis, Ni composition of the design composition, C _m (Co) is weight percent composition basis, the average Co composition between core particles, C ₀ ( Co) is the Co composition of the design composition, based on the weight percent composition. That is, C _m (Al) in the equation (4) corresponds to a average Al composition of the expression 1 related above, C _m (Ni) in the expression (5) corresponds to a mean Ni composition of the formula (2) related above, C _m in equation (6) ( Co) corresponds to the average Co composition defined in equation 3. Further, C ₀ (Al) may be Al weight% contained in the AlNiCo-based alloy molten metal used for atomizing, C ₀ (Ni) may be Ni weight% contained in the AlNiCo-based alloy molten metal used for atomizing A, C ₀ (Co) may be Co% by weight contained in the AlNiCo alloy molten metal used for atomizing. At this time, in order to improve the composition uniformity, it is advantageous for the alloy molten metal to melt and solidify the metal powders constituting the alloy according to the predetermined composition in an inert atmosphere, and then to melt the solid ingot in an inert atmosphere. . In the case of such an advantageous example, the design composition, which is the composition of the alloy molten metal, may be a composition based on a mixture of metal powders forming an alloy for ingot production. However, the design composition cannot be interpreted as being limited to the reference composition of the mixture of the raw metal powders, and may mean the composition of the ingot itself, or the composition of the molten ingot (alloy molten metal) itself for atomizing. .

As in relations 4, 5, and 6, the AlNiCo-based magnetic particles according to the present invention are characterized in that the composition of the core particles for determining the magnetic properties is substantially the same as the designed composition, and the magnetic particles having a deviation from the design composition are suppressed. have.

In a manufacturing method, ingot and molten metal are manufactured under an inert atmosphere, and when the molten metal is sprayed, it is rapidly cooled by a water-based refrigerant (a refrigerant containing water) to prevent segregation, and an antioxidant contained in the water-based refrigerant. It is practically the same as the design composition that satisfies the relations 4, 5 and 6 only when the composition change due to oxidation in the spraying process is prevented, in particular, the interparticle composition change due to the oxidation of an element with strong oxidizing properties such as Al Core particles having a composition can be produced, and furthermore, composition uniformity satisfying relations 1, 2, and 3 can be secured.

The magnetic particles according to the present invention may include the above-described two aspects in terms of deviation from the design composition and composition deviation between particles, but the two aspects should not be interpreted as being independent of each other, and the present invention is the first aspect. And magnetic particles belonging to both of the second embodiments.

That is, the magnetic particles according to an example of the present invention include core particles containing Al, Ni and Co; And an inorganic shell surrounding the core particles, wherein the hard magnetic particles include, the core particles are ultra-fine particles having a particle size D ₅₀ of 12 μm or less in the cumulative distribution of the core particles, and the core particles are as described above. Equations 1, 2, and 3 have composition uniformity, and the core particles are produced by an atomizing method using a refrigerant containing at least water, and the core particles contain Al, Ni, and Co used for atomizing. Based on the design composition, which is the composition of the alloy molten metal, it may have a composition that satisfies Equations 4, 5, and 6 described above.

The core particles may be any alloy containing Al (aluminum), Ni (nickel), and Co (cobalt) excellent in coercive force, saturation magnetization, and residual magnetization. As a specific example, the core particles may include one or two or more fourth elements selected from Fe, Cu, Ti, and Si; and other inevitable impurities. As a specific and practical example, the core particles contain Al, Ni, and Co, and a non-ferrous system selected from one or more of the group consisting of Cu, Si, and Ti; Fe-based iron-based; And other unavoidable impurities.

AlNiCo-based magnetic particles, like the compositional uniformity of Al, Ni, and Co, also have a feature of containing the fourth element extremely uniformly. In detail, the core particles have a composition uniformity in which a value based on the composition by weight percent and an average fourth element composition (average content by weight percent) between core particles divided by a standard deviation of the composition of the fourth element is 10 or more. That is, the UNF (4th element) may be 10 or more, and the UNF (4th element) is based on the composition by weight%, and the average 4th element composition (average 4th element weight%) between core particles is the standard of the 4th element composition. It may be a value divided by the deviation (standard deviation of the weight percentage of the fourth element), and when the fourth element is two or more elements, UNF (fourth element) may be 10 or more for each of the two or more elements. At this time, the average fourth element composition between the core particles may mean the average value of the fourth element composition of each of the core particles of the magnetic particles forming the magnetic particle group, and the standard deviation of the fourth element composition is the magnetic particles forming the magnetic particle group It goes without saying that it can mean the standard deviation in the composition of the fourth element of each of the core particles of the particles.

As a practical example, the core particles may further contain Ti, Fe, and Cu together with Al, Ni, Co, and UNF (Ti), in which the fourth element is Ti, and UNF (Fe), in which the fourth element is Fe and Each of the UNF (Cu) having four elements Cu may be 10 or more. As a more practical example, UNF (Ti) may be 15 or more, UNF (Fe) may be 35 or more, and UNF (Cu) may be 30 or more.

That is, in one practical and advantageous example, the core particles may contain Ti, Fe, and Cu together with Al, Ni, Co, 11 or more UNF (Al), 40 or more UNF (Ni), 30 or more UNF (Co), 15 or more UNF (Ti), 35 or more UNF (Fe) and 30 or more UNF (Cu) satisfies a high degree of composition uniformity.

In the AlNiCo-based magnetic particles according to a practical and advantageous example, the core particles are based on a weight percentage based on 100% of the total weight of the core particles, Al 4 to 12%, Ni 10 to 20%, Co 15 to 25%, Ti 1 to 10%, Cu 0.5 to 5%, the balance of Fe and other unavoidable impurities. In the AlNiCo-based magnetic particles according to another practical and advantageous example, the core particles are based on a weight percent based on 100% of the total weight of the core particles, Al 4 to 12%, Ni 10 to 20%, Co 15 to 25%, Ti 1 to 10%, Cu 0.5 to 5%, Si 0.1 to 1%, the balance may include Fe and other unavoidable impurities. At this time, the composition of the core particles refers to the average weight percent of the average weight percent of one element contained in each of the core particles of the magnetic particles constituting the magnetic particle group, and corresponds to the composition of the average one element used when defining UNF of one element can do.

The core particles may contain 4 to 12% by weight, advantageously 5 to 10% by weight, even more advantageously 6 to 9% by weight of Al. When the aluminum content satisfies this composition category, the effect of preventing sintering is sufficient in subsequent heat treatment for segregation and magnetic property control, so that the shape of the fine particles secured by the water spray method can be maintained, and the mechanical properties of the core particles are deteriorated. It is advantageous because it can be prevented and improve the properties of saturation magnetization and residual magnetization.

The core particles may contain 10 to 20% by weight, advantageously 12 to 18% by weight, even more advantageously 13 to 16% by weight Ni. When the content of nickel satisfies this composition category, it is advantageous because the coercive force and residual magnetization can be simultaneously increased.

The core particles may contain 15 to 25% by weight, advantageously 17 to 25% by weight, even more advantageously 17 to 23% by weight of Co. When the content of cobalt satisfies this composition category, it is advantageous to increase the coercive force, which is advantageous for cost reduction.

Ti and Cu can further improve the coercive force of the Al-Ni-Co alloy. The core particles may contain 1 to 10% by weight of Ti, advantageously 2 to 8% by weight, and even more advantageously 3 to 6% by weight of Ti to prevent residual magnetization reduction and improve coercive force. . In addition, to prevent residual magnetization reduction and improve coercive force, the core particles may contain 0.5 to 5% by weight of Cu, advantageously 1 to 4% by weight, and even more advantageously 1 to 3% by weight of Cu. You can.

The core particles may contain 0.1% by weight or more of Si to favor the stable shape of the fine particles during deoxidation and spraying of the molten metal during production, but it is preferable to contain 1% by weight or less to prevent deterioration of magnetic properties. Specifically, the core particles may contain 0.4 to 0.7% by weight of Si in terms of deoxidation, maintaining particulate shape, and suppressing deterioration of magnetic properties. However, as shown in the embodiment, when producing an ingot in an inert atmosphere, melting the ingot in an inert atmosphere to prepare a molten metal, when using a refrigerant (cooling medium) containing an antioxidant with water when spraying the molten metal, Oxidation can be sufficiently suppressed in the particle formation process of the molten metal, so that the magnetic particles having a composition substantially the same as the composition uniformity and the design composition described above can be produced without the molten metal containing a deoxidizing agent such as Si that degrades the magnetic properties. .

In the AlNiCo-based magnetic particles according to an embodiment of the present invention, the core particles are Equations 7 and 8 may be further satisfied.

Equation 7: 3 μm ≤ D50 ≤ 12 μm

Equation 8: 10 μm ≤ D90 ≤ 20 μm

As described above, D ₅₀ in Equation 7 is a particle size corresponding to 50% in the cumulative distribution of particle diameters, and D ₉₀ in Equation 8 is a particle size corresponding to 90% in the cumulative distribution of particle diameters. Substantially, D ₅₀ may be 3 to 9 μm, and D ₉₀ may be 10 to 15 μm.

When the core particle is an ultrafine particle having a D ₅₀ of 12 μm or less, the distribution of the particle size may also affect the magnetic properties. When the AlNiCo-based magnetic particles satisfy Expressions 7 and 8, printability can be secured, and printing defects such as nozzle clogging can be improved during the printing process, and changes in magnetic properties due to size variations can be suppressed. Therefore, AlNiCo-based magnetic particles may have more uniform magnetic properties.

In order to use the magnetic material as a security element, it is necessary to conceal the dark color inherent to the magnetic particles. Accordingly, as proposed by the present applicant, by using a technique of pale-colouring a magnetic body wrapped with a magnetic metal shell of a particle (see Korean Patent Registration No. 1341150), it is possible to conceal the dark color inherent to the magnetic particles.

In the AlNiCo-based magnetic particles, the inorganic shell may serve to conceal the dark colors inherent to the core particles containing Al, Ni, and Co, and to act so that the AlNiCo-based magnetic particles have a pale color.

Specifically, the inorganic shell may include a metal shell, and further include a dielectric shell positioned on the top of the metal shell (ie, the surface side of the metal shell) and / or the bottom of the metal shell (the core particle side of the metal shell). can do. The dielectric shell may serve to improve the binding force between the metal shell and the core particles, or to protect the metal shell from the outside to improve durability.

Through various previous experiments over a long period of time, it was confirmed that the composition uniformity of the core particles, the particle size distribution, and the uniformity of the metal shell, which is the main component for pale coloration, also have a significant effect on the magnetic properties of the AlNiCo-based magnetic particles.

Thus, in the AlNiCo-based magnetic particles according to the present invention, the inorganic shell may include a metal shell, and the metal shell may have thickness uniformity satisfying the following Equations 9 and 10.

Equation 9: 50 nm ≤ t _m ≤ 100 nm

Equation 10: σ _t ≤ 30 nm

In equation 9, t _m is the average thickness of the metal shell, and in equation 10, σ _t is the standard deviation of the metal shell thickness. At this time, the standard deviation of the average thickness and thickness of Equation 9 and Equation 10 is the average thickness of the thickness depending on the position of the one metal shell surrounding one core particle based on the one magnetic particle, and the deviation is also the standard of the thickness at one metal shell. Deviation. Magnetic particles belonging to the AlNiCo-based magnetic particle group may satisfy Equations 9 and 10, respectively.

That is, the magnetic particles belonging to the AlNiCo-based magnetic particle group each have an average thickness of 50 to 100 nm of the metal shell, and at the same time, each of the magnetic particles belonging to the AlNiCo-based magnetic particle group has a metal shell thickness variation within 30 nm, It may be substantially 1 nm to 10 nm.

The metal shell may be one or two or more metals selected from copper, nickel, gold, platinum, silver, aluminum, and chromium. Silver is more effective for pale coloration, and furthermore, the silver shell provides infrared reflectivity to AlNiCo-based magnetic particles. It is more advantageous than can be given.

The dielectric shell located on the upper, lower or upper and lower portions of the metal shell may be a dielectric selected from titanium oxide, silicon oxide, aluminum oxide, zinc oxide, zirconium oxide, calcium carbonate, magnesium fluoride and zinc sulfide. have. The thickness of the dielectric shell may be 10 to 100 nm in terms of stably improving durability and improving pale coloration, but is not limited thereto.

AlNiCo-based magnetic particles according to an embodiment of the present invention may have a coercive force of 100 to 500 Oe, saturation magnetization (Ms) is 50 to 150 emu / g, and residual magnetization (Mr) is 10 to 40 emu / g day. You can. Specifically, AlNiCo-based magnetic particles may have a coercive force of 100 to 500 Oe, saturation magnetization (Ms) may be 50 to 70 emu / g, and residual magnetization (Mr) may be 15 to 30 emu / g. The magnetic properties of the coercive force, saturation magnetization, and residual magnetization are not distinguished from soft magnetic particles by general recognition equipment, and enhanced security performance that can be distinguished from soft magnetic particles by expensive recognition equipment can be secured. That is the magnetic properties.

The AlNiCo-based magnetic particles have the above-described compositional uniformity, a strictly designed design composition to secure the planned magnetic properties, and advantageously by having the compositional uniformity, design composition, uniformity of particle size and uniformity of metal shell thickness, Security elements designed in a high-level shape, such as fine linearity, can also be stably and reproducibly detected with soft magnetic particles and reproducible by expensive recognition equipment, thereby greatly improving security characteristics.

Further, in general, the magnetic particles have a property of absorbing infrared rays, but the AlNiCo-based magnetic particles according to an advantageous embodiment of the present invention may have a property of reflecting infrared rays. Furthermore, the AlNiCo-based magnetic particles according to an advantageous embodiment of the present invention have a very low surface roughness with a uniform thickness of a metal shell, and have a very good infrared reflectance reflecting more than 60% of infrared rays (infrared rays of 900 nm wavelength) based on 900 nm wavelength. Can have It is possible to implement a security element having a highly shaped shape including fine linearity, with magnetic properties in which the magnetic particles according to an embodiment of the present invention are not distinguished from soft magnetic particles by general recognition equipment, and have high infrared reflection. It means that you can have security characteristics. In other words, it means that the magnetic properties, security pattern (shape of the security element), and infrared light are made of various security with AlNiCo-based magnetic particles, which are a single material. In particular, the AlNiCo-based magnetic particles according to an embodiment of the present invention can realize soft magnetic properties with substantially the same composition, and thus can distinguish the difference from the soft magnetic particles with a conventional composition analysis device and a general magnetic recognition device. No, the forgery of security elements is practically impossible.

In addition, in the AlNiCo-based magnetic particles according to the present invention, the hard magnetic particles may have a brightness (L *) value measured by a color difference meter of 60 or more, preferably 70 or more. In this case, limiting the upper limit value is meaningless, but in practice, the upper limit of the L * value may be 95. When the hard magnetic particles have an L * value in the above-described range, hiding properties are further improved, and thus security can be further improved.

The present invention includes a method of manufacturing the AlNiCo-based magnetic particles described above. The manufacturing method according to the present invention includes all the contents described above in the AlNiCo-based magnetic particles.

In the manufacturing method of the present invention, terms such as a cooling medium containing water, an aqueous spray and / or an aqueous cooling medium, etc. should be interpreted to mean at least water, and limited to mean that the cooling medium is made of liquid. It should not be interpreted as being included, and if the cooling medium contains a gaseous phase of inert gas together with water.

A method of manufacturing AlNiCo-based magnetic particles according to the present invention comprises the steps of: a) preparing an ingot by melting and solidifying a raw material containing Al, Ni and Co in an inert atmosphere; b) melting the prepared ingot in an inert atmosphere and preparing particulates by atomization using a cooling medium containing water and an antioxidant; c) heat-treating the produced fine particles; d) airflow classifying the heat-treated fine particles to produce AlNiCo-based core particles having a D ₅₀ of 12 μm or less; And e) forming an inorganic shell on the prepared AlNiCo-based core particles.

As described above, when using a gas atomization (gas atomization method), the cooling rate is slow, the production of particles having uniform magnetic properties is substantially very difficult, and further, the size required for printing (eg, D ₅₀ ≤ 12 μm ), The ultra-fine particle yield is only about 5%, which is unsuitable for mass production.

The manufacturing method according to the present invention, by using a cooling medium containing water, can be rapidly cooled to produce ultra-fine particles of dense tissue with segregation-prevented in very good yield (for example, 35% or more), As the cooling medium contains an antioxidant, it is designed to have excellent composition uniformity (low compositional deviation) as described above, by preventing heterogeneous oxidation of certain highly oxidizing elements in particles produced by water, Core particles having a composition can be produced.

As compositional variation is caused by heterogeneous oxidation of elements with strong oxidizing properties (eg, Al, Ti, etc.), spraying in an inert atmosphere and ingotization (a) by melting of the raw material in an inert gas atmosphere) The remelting of the ingot for the step (b)) is performed, thereby suppressing the occurrence of compositional deviations up to the step immediately before spraying, and by using an aqueous cooling medium containing an antioxidant during spraying, the occurrence of compositional deviations in the spraying process Can be suppressed.

Thereafter, the fine particles produced by spraying may be heat treated to improve coercive force, and by performing air flow classification on the fine particles subjected to heat treatment, D50 is 12 μm or less, preferably D ₅₀ and D ₉₀ are expressed in Equations 7 and Equations. Core particles having a very narrow size distribution satisfying 8 and an ultrafine size can be produced.

In addition, after the core particles are prepared, when forming a metal shell in the step of forming an inorganic shell, a metal shell is formed using electroless plating, but electroless plating is performed at a low temperature of 5 ° C. or less, specifically 1 to 5 ° C. By doing so, it is possible to manufacture a metal film having a thin, uniform, and very low surface roughness satisfying the expressions 9 and 10.

Hereinafter, a detailed manufacturing method will be described, but in detailing the manufacturing method, the size, distribution, composition, element content, magnetic properties, inorganic shell material, and thickness of the core particles are similar to those described above in the AlNiCo-based magnetic particles. Is the same. Accordingly, the method of manufacturing the AlNiCo-based magnetic particles includes all the contents of the above-mentioned related configurations in the AlNiCo-based magnetic particles.

The ingot can be produced by melting a raw material in which the powder of each element containing Al, Ni and Co is mixed in an inert atmosphere so as to have the same composition as the designed core particle, and manufacturing the molten metal, and cooling the prepared molten metal in an inert atmosphere. have. However, when the core particles contain iron, medium carbon steel (0.15 to 0.3 wt% C-containing steel) having an antioxidant effect can be used instead of iron powder, but ingotization and melting of the ingot is performed in an inert atmosphere, and oxidation is performed. Since spraying is performed by an aqueous cooling medium containing an inhibitor, medium carbon steel is not required, and can be optionally used. Thus, it goes without saying that the present invention cannot be limited by the type of iron raw material. Accordingly, the ingot may be an AlNiCo alloy ingot comprising Al, Ni and Co, specifically, one or more elements selected from Fe, Cu, Si and Ti together with Al, Ni and Co and other unavoidable impurities. It may be an AlNiCo alloy ingot comprising a. More substantially, the ingot may be an AlNiCo alloy ingot comprising Ti, Fe, Cu and other inevitable impurities along with Al, Ni and Co. As another practical example, the ingot may be an AlNiCo alloy ingot comprising Ti, Fe, Cu, Si, and other inevitable impurities along with Al, Ni, and Co.

The composition of the raw material, the composition of the ingot, or the composition of the molten metal corresponding to the design composition according to a practical and advantageous example is based on weight percent, Al 4 to 12%, Ni 10 to 20%, Co 15 to 25%, Ti 1 to 10 %, Cu 0.5 to 5%, balance Fe and other unavoidable impurities. The composition of the raw material, the composition of the ingot, or the composition of the molten metal corresponding to the design composition according to another practical and advantageous example is based on a weight percent based on 100% of the total weight of the core particles, Al 4 to 12%, Ni 10 To 20%, Co 15 to 25%, Ti 1 to 10%, Cu 0.5 to 5%, Si 0.1 to 1%, balance Fe and other unavoidable impurities.

At this time, the composition of the raw material corresponding to the design composition, the composition of the ingot or the composition of the molten metal may contain 4 to 12% by weight, advantageously 5 to 10% by weight, and even more advantageously 6 to 9% by weight of Al. have. In addition, the composition of the raw material corresponding to the design composition, the composition of the ingot or the composition of the molten metal may contain 10 to 20% by weight, advantageously 12 to 18% by weight, and even more advantageously 13 to 16% by weight of Ni. have. In addition, the composition of the raw material corresponding to the design composition, the composition of the ingot or the composition of the molten metal may contain 15 to 25% by weight, advantageously 17 to 25% by weight, and even more advantageously 17 to 23% by weight of Co. have. In addition, the composition of the raw material, the composition of the ingot, or the composition of the molten metal corresponding to the design composition contains 1 to 10% by weight of Ti, advantageously 2 to 8% by weight, and even more advantageously 3 to 6% by weight of Ti. can do. In addition, the composition of the raw material, the composition of the ingot, or the composition of the molten metal corresponding to the design composition contains 0.5 to 5% by weight of Cu, advantageously 1 to 4% by weight, and even more advantageously 1 to 3% by weight of Cu. can do. In addition, the composition of the raw material corresponding to the design composition, the composition of the ingot or the composition of the molten metal is the composition of the raw material corresponding to the design composition, the composition of the ingot or the composition of the molten metal is 0.1 wt% or more Si, specifically 0.4 to 0.7 wt% Si may be contained, but like the above-mentioned reasons for carbon steel, Si may be selectively used if necessary.

The ingot melting of step b) may be a process of melting an ingot in an inert atmosphere, and in detail, it may be a process of melting an ingot in an inert atmosphere by induction heating for high frequency, but melting is performed in an inert atmosphere to prevent oxidation. It is not limited by the specific heating method. As a specific and non-limiting example, the temperature at high frequency melting in an inert atmosphere may be 1300 to 1800 ° C.

The spray of step b) may be performed using an aqueous cooling medium containing water and an antioxidant, and may be performed by spraying the aqueous cooling medium through an injection nozzle of a ring shape.

When the ingot melt melted for spraying is called an AlNiCo-based molten metal, in order to suppress oxidation when granulating the AlNiCo-based molten metal by a water-based fluid, the water-based cooling medium may contain water and an antioxidant, and an antioxidant May include one or more selected from a reducing organic solvent and a reducing organic compound. Particularly, the antioxidant may contain a reducing organic compound containing urea, and when spraying is performed by an aqueous cooling medium containing urea and water, heterogeneous oxidation occurs during the granulation of the granulated AlNiCo-based molten metal. Core particles satisfying the above-mentioned relational expressions 1, 2, and 3 can be significantly suppressed, and further, oxidation is significantly suppressed during particle formation, thereby satisfying relational expressions 4, 5, and 6, substantially design composition Matching core particles can be produced.

Specifically, the cooling medium may contain 10 to 100 parts by weight of urea based on 100 parts by weight of water, advantageously 15 to 100 parts by weight of urea, more advantageously 20 to 100 parts by weight of urea, and the content of such urea is AlNiCo It is a content that can substantially completely inhibit oxidation by water and heterogeneous oxidation by water when granulating the molten metal.

However, in the present invention, the antioxidant contained in the cooling medium cannot be interpreted as being limited to urea alone, and if necessary, the cooling medium may further include a reducing organic solvent together with the above-mentioned reducing organic compound containing urea. Of course. It is a reducing organic solvent, which has excellent miscibility with water, has a high boiling point, and has excellent reducing ability. Alkanolamines are advantageous. Alkanolamines are monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), and monoisocyanate. Propylamine (MIPA), diisopropylamine (DIPA), or mixtures thereof, but the present invention is not limited thereto.

When the cooling medium further includes a reducing organic solvent, the cooling medium is 30 parts by weight or less of a reducing organic solvent based on 100 parts by weight of water, specifically 1 to 30 parts by weight, so as not to inhibit the rapid cooling effect by water. Specifically, it may contain 5 to 20 parts by weight of a reducing organic solvent, but the present invention is not limited thereto.

In addition, when the cooling medium further includes a gas phase containing an inert gas, water: an inert gas so that a rapid cooling effect by water to prevent segregation and generation of unwanted abnormalities (eg, Al-rich phase) can be maintained. It is advantageous that the volume ratio of the gas phase comprising 1: 0.05 to 0.3.

When spraying, the spray pressure of the cooling medium containing water and an antioxidant is 500 bar or more, which is advantageous for the production of ultrafine particles having a D ₅₀ of 12 μm or less. Specifically, in order to obtain ultrafine particles having a D ₅₀ of 12 μm or less in excellent yield, the injection pressure of the cooling medium may be 500 to 1000 bar, more specifically 500 to 800 bar.

AlNiCo-based fine particles may be obtained by the above-described spraying process, and then a step of heat-treating the AlNiCo-based fine particles produced by spraying may be performed. In the case of the gas spraying method, heat treatment should be performed to remove segregation and unwanted abnormalities (specific examples, γ phase) caused by slow cooling while improving magnetic properties, but in a manufacturing method according to an embodiment of the present invention In the case of the obtained AlNiCo-based fine particles, segregation and phase separation (abnormal formation) are prevented by rapid cooling, and it is sufficient if heat treatment under favorable conditions is performed to improve the magnetic properties of the AlNiCo-based fine particles. Specifically, the heat treatment in step c) may be performed at a temperature of 700 to 800 ° C. in a normal inert or reducing atmosphere. The heat treatment time may be achieved as long as the desired magnetic properties are improved and the degree of strong binding between AlNiCo-based fine particles may be performed, but may be performed for 30 to 2 hours as a practical example, but the present invention will be limited by the specific time at which the heat treatment is performed. Of course not.

If necessary, after the first heat treatment at 700 to 800 ℃, the second heat treatment at a temperature relatively lower than the first heat treatment, and a multi-stage heat treatment can be performed by performing a third heat treatment at a temperature relatively lower than the second heat treatment temperature, The coercive force of the AlNiCo-based fine particles can be further improved by the multi-stage heat treatment. Specifically, if necessary, a second heat treatment may be performed for 2 to 4 hours at a temperature of 600 to 700 ° C. (not including 700 ° C.) after the first heat treatment is performed at 700 to 800 ° C., and the second heat treatment may be performed. After being performed, a third heat treatment may be performed at 550 to 600 ° C. (not including 600 ° C.) for 10 to 15 hours.

The step d) may be a step of manufacturing airflow classifying on the fine particles subjected to the heat treatment to produce core particles having a D ₅₀ of 12 μm or less. As is known, the cyclone type airflow classification is known by the centrifugal force and fluid drag force of the high-speed airflow, so that the coarse particles move to the outer wall of the classifier and turn along the wall surface to collect it, and the fine particles move to the center (inner) of the classifier to air It can be exhausted and recovered while orbiting together, and the adjustment of the classification point can be mainly controlled by the rotation speed of the classifier and the amount of air injected. The airflow classification is very suitable for the present invention because it allows precise classification of very fine particles, and the classified particles have a very narrow particle size distribution. For a specific and non-limiting example, for classifying and recovering core particles having a D ₅₀ of 12 μm or less, and advantageously satisfying the equations 7 and 8 by classifying airflow, for fines subjected to gas spraying and multistage heat treatment. , The rotational speed at the time of air flow classification may be 2500 to 8000 rpm, and the air injection amount may be 2 to 10 m ³ / min. However, in the field of controlling particle size distribution by air flow classification, the target classification is performed by controlling the main variables of the known classifier to obtain particles having the desired average size and distribution according to the detailed structure of various commercial air flow classifiers. It is obvious that it can be performed.

Core particles having a D ₅₀ of 12 μm or less obtained by airflow classification, advantageously particles satisfying Expressions 7 and 8, are very suitable for fine linear pattern printing, and have difficulties such as printing defects that may occur during the printing process. It can be prevented, it is advantageous because it can prevent the change in the magnetic properties according to the particle size variation.

Step e) is a step of forming a shell on the core particles obtained by air flow classification, and step e) may include a step of forming a metal shell. Specifically, forming a dielectric shell on the core particles; And forming a metal shell over the dielectric shell; however, if necessary, the same or different dielectric shell forming steps for protecting the metal shell over the metal shell may be further performed.

The step of forming the dielectric shell may be any method commonly used to coat the dielectric on the particles, but it is advantageous to use a sol-gel method in terms of thin and uniform film formation. Specifically, considering the dielectric material of the shell to be formed, it may be performed using an alkoxide sol-gel method or a colloidal sol-gel method. As a specific and non-limiting example, titanium tetrabutoxide (Titanium) is used to form a titanium oxide shell. After mixing the core particles dispersed in a dispersion medium containing water in a titanium sol in which a titanium precursor such as Tetrabuthoxide) is dissolved, the core particles can be separated and dried to produce core particles having a titanium oxide shell.

The step of forming the metal shell may be any method commonly used to coat the metal on the particles, but it is advantageous to use electroless plating in terms of thin and uniform film formation. It forms a satisfactory thin and uniform metal film, has a low surface roughness, and allows magnetic particles having extremely excellent infrared reflectance of 60% or more based on 900 nm wavelength to be produced. It is advantageous to form a metal shell using plating. Various electroless plating solutions may be used in consideration of the metal material of the metal shell. According to an advantageous example, in the case of forming a silver shell with a metal shell, the plating bath for electroless plating is a silver precursor (for example, silver nitrate, etc.), a pH adjusting agent (for example, KOH, etc.), a complex (representative work) Examples include ammonia water, ammonium salts, etc.), solvents, and reducing agents. At this time, the reducing agent is monosaccharides, glucose, fructose, galactose, sodium tartrate, sodium tartrates, potassium tartrate, and sodium tartrate. Potassium (potassium sodium tartrate), calcium tartrate (calcium tartrate), stearyl tartrate (stearyl tartrate), may include formaldehyde and the like. At this time, the pH of the plating bath can be adjusted to 7 to 10 by a pH adjusting agent, of course, the plating bath may further include known additives for uniform plating.

The security ink composition according to the present invention may be used as an ink for various purposes such as intaglio printing, screen printing, flat plate printing, and preferably used for intaglio printing, having a high viscosity, uniform elasticity and high durability In can be good.

The security ink composition according to the present invention may have a viscosity between 3 Pa.s to 15 Pa.s, preferably 5 to 10 Pa.s at 40 ° C. When the viscosity range is satisfied, high viscosity, uniform elasticity, and high durability can be secured, and this viscosity range can be adjusted according to the type and content of each component of the security ink composition.

The security ink composition according to the present invention includes AlNiCo-based magnetic particles, varnish, pigment, surfactant, wax and solvent as described above.

Specifically, the security ink composition is 5 to 15 wt% of the AlNiCo-based magnetic particles, 10 to 40 wt% of the varnish, 30 to 70 wt% of the pigment, 1 to 20 wt% of the surfactant, and 1 to 15 wt% of the wax And it may include a solvent 1 to 30% by weight, but is not limited thereto.

As an example, the varnish includes a thermoplastic resin, a thermosetting resin, or a photo-curable resin, and is not limited to the type as long as it is dissolved in an organic solvent. Examples of specific varnishes include thermoplastic resins, petroleum resins, casein, shellac, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrocellulose, cellulose acetate butyrate, cyclized rubber, chlorinated rubber, oxidized rubber, hydrochloric acid rubber, and phenolic resin. Alkyd resin, polyester resin, unsaturated polyester resin, amino resin, epoxy resin, vinyl resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, ethylene vinyl acetate resin, acrylic resin, methacryl resin, polyurethane resin , Silicone resin, fluorine resin, dry oil, synthetic dry oil, styrene-maleic acid resin, styrene-acrylic resin, polyamide resin, or butyral resin. Examples of the thermosetting resin include epoxy resins, phenol resins, benzoguanamine resins, melamine resins, and urea resins. As a photocurable resin (photosensitive resin), a (meth) acrylic compound or cinnamic acid having a reactive substituent such as an isocyanate group, an aldehyde group or an epoxy group is reacted with a linear polymer having a reactive substituent such as a hydroxyl group, a carboxyl group, or an amino group, and (( A resin in which a photocrosslinkable group such as a meta) acryloyl group or a styryl group is introduced into the linear polymer can be used. In addition, linear polymers containing acid anhydrides such as styrene-maleic anhydride copolymers or α-olefin-maleic anhydride copolymers are halved by (meth) acrylic compounds having hydroxyl groups such as hydroxyalkyl (meth) acrylates. It is also possible to use esterified ones.

The pigment is not particularly limited, for example, soluble azo pigment, insoluble azo pigment, phthalocyanine pigment, halogenated phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, isoindoleline pigment, perylene pigment, perinone pigment, Dioxazine pigments, anthraquinone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, andandron pigments, indanthrone pigments, flavanthrone pigments, pyranthrone pigments, or diketopyrrolopyrrole pigments.

The surfactant is not limited, and any one or more selected from the group consisting of fluorinated surfactants, polymerizable fluorinated surfactants, siloxane surfactants, polymerizable siloxane surfactants, polyoxyethylene surfactants, and derivatives thereof may be mentioned. have.

The wax is not limited to any type if it is a powder (powder) type having an effect of reducing the tack of the resin, for example, polyethylene wax, amide wax, erucamide wax, polypropylene wax, paraffin wax, Teflon and Carnauba may include one or more selected from wax, and the like, but is not limited thereto.

The solvent is a general organic solvent, and is not limited to the type as long as it can uniformly mix substances such as wax, pigment, and varnish. Specific examples of the usable solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, acetone, hexane, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate , Diethylene glycol diethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether acetate, or the like.

The present invention includes a price certificate containing AlNiCo-based magnetic particles.

In detail, the present invention includes oil price certificates such as banknotes, checks, stamps, gift certificates, vouchers, bonds, etc. containing the above-described AlNiCo-based magnetic particles as a security element. In this case, the security element including the AlNiCo-based magnetic particles may have a shape designed for security such as an image (including a part of a shape forming an image), numbers, letters, and geometric patterns.

Hereinafter, the present invention will be described in detail through examples, but these are for explaining the present invention in more detail, and the scope of the present invention is not limited by the following examples.

Raw powder (aluminum powder, nickel powder, cobalt powder, titanium powder, copper according to the design composition of 6 wt% Al, 15 wt% Ni, 22 wt% Co, 4 wt% Ti, 3 wt% Cu and 50 wt% Fe Ingots were prepared by mixing powder, iron powder, and purity of the raw material powder ≥ 99.9%), dissolving in an inert atmosphere, and then solidifying. 1 kg of the prepared ingot was heated by a high frequency generator and placed in a crucible placed under an inert atmosphere, and the temperature was maintained at 1650 ° C to form an AlNiCo-based molten metal. For atomization, the molten metal was injected into a vacuum atomization confinement, and the cooling medium, an aqueous urea solution in which 25% by weight of urea was dissolved, was sprayed at 600 bar through an annular spray nozzle.

The produced fine particles were heat treated at 750 ° C. for 1 hour under an argon gas atmosphere.

The particles obtained after the heat treatment were air-classified in a cyclone manner under a condition of a rotational speed of 7500 rpm and an air injection amount of 2.8 m ³ / min to obtain core particles having a D ₅₀ of 7.8 μm and a D ₉₀ of 14.1 μm. Thereafter, the core particles obtained by air flow classification were washed twice with ethanol, and then dried at 60 ° C.

After sampling randomly about 1 g from the obtained core particles, elemental analysis (10 kV, 100 sec) was performed on the central region of the particle cross section by EDS (Energy Dispersive X-Ray Spectroscopy, FEI company, Magellan400), and each of the 50 particles. Elemental analysis was performed, and the average composition of each element and the standard deviation of the composition were calculated, and the results were shown in Table 1 (Table 1-1 Al, Ni, Co analysis results, Table 1-2 Ti, Cu, Fe analysis results). Organized. In addition, the values defined by Equations 4, 5, and 6, that is, the degree deviating from the design composition are shown in Table 2 as 'DEV'.

Separately, for the washed core particles, 1 g of core particles, 1 ml of tetrabuthoxy titanium (TBOT) (Aldrich), and 1 ml of distilled water were added to 170 ml of ethanol, and then 300 rpm was added for 2 hours at a temperature of 85 ° C. After stirring at a rotational speed, a titanium oxide shell (50 nm thick) was coated on the surface of the core particles. The core particles coated with the titanium oxide shell were separated and collected with a magnet, and then washed and dried twice with ethanol.

Thereafter, 21 g of silver nitrate (AgNO ₃ ) and 4 g of sodium hydroxide (NaOH) were added to 1200 mL of distilled water, and then 34 mL of ammonium hydroxide (NH 4 OH) was added thereto, followed by stirring to change the brown precipitate to a transparent silver amine complex solution. 60 g of the titanium oxide shell-coated core particles were added to the silver amine complex solution maintained at 3 ° C., followed by stirring at 300 rpm for 30 minutes. A solution (3 ° C) in which 20 g of glucose and 1.5 g of potassium tartrate were dissolved in 400 mL of distilled water was added to a silver amine complex solution (3 ° C) in which core particles coated with a titanium dioxide shell were dispersed, and then 300 After stirring at rpm speed for 1 hour, a silver shell having a thickness of 58.4 nm was formed on the core particle on which the titanium oxide shell was formed to prepare AlNiCo-based magnetic particles. Thereafter, the prepared magnetic particles were separated with a magnet, washed twice with ethanol, and dried at 60 ° C.

The coercive force, saturation magnetization (Ms), and residual magnetization (Mr) of the prepared magnetic particles were measured using a vibrating sample magnetometer, Lakeshore, 7400 series (VSM), and the results are summarized in Table 3.

[Comparative Example 1]

Performed in the same manner as in Example 1, except that water was used as a cooling medium during spraying, core particles were prepared in the same manner as in Example 1, and then, in the same manner as in Example 1, except that a room temperature solution was used for silver shell production. Magnetic particles were prepared.

The core particles prepared in Comparative Example 1 also confirmed the composition uniformity of the core particles in the same manner as in Example 1, which was summarized in Table 1, and also, the values defined by Equations 4, 5, and 6, that is, The degree deviating from the design composition is shown in Table 2 as 'DEV'. In addition, the magnetic properties of the prepared magnetic particles were also measured in the same manner as in Example 1 and summarized in Table 3.

[Table 1-1]

[Table 1-2]

In Table 1 (Table 1-1 and Table 1-2), C _m (A) is the average weight percent of element A of the core particles, and σ (A) is the standard deviation of element A between core particles (based on weight percent). And UNF (A) is C _m (A) / σ (A). In addition, the reason why the sum of C _m between elements in Table 1 is not 100 is due to inevitable impurities.

As can be seen from Table 1, in the case of AlNiCo-based magnetic particles according to the present invention, D ₅₀ of the core particles is 7.8 μm and D ₉₀ is 14.1 μm, while having remarkably improved composition uniformity. It can be seen that.

[Table 2]

As can be seen from Table 2, in the case of the core particles prepared in the Examples, it can be seen that magnetic particles having a composition substantially the same as the composition of the designed raw material are produced.

[Table 3]

As can be seen from Table 3, segregation and abnormality are prevented by quenching, and compositional deviation due to oxidation is prevented, and thus, through simple and very short heat treatment at 750 ° C. for 1 hour, it is not distinguishable from softness with ordinary measuring equipment, and is It can be seen that hard magnetic particles having magnetic properties capable of securing security are manufactured.

1 is a scanning electron microscope photograph of AlNiCo-based magnetic particles prepared in Example 1. As can be seen in Figure 1, it can be seen that substantially spherical particles are produced, and it can be seen that a silver shell is formed uniformly and stably by low-temperature electroless plating at 3 ° C.

FIG. 2 is a scanning electron micrograph observing the cross section of the prepared AlNiCo-based magnetic particles and measuring the thickness distribution of the silver shell. As can be seen in FIG. 2, it can be seen that the average thickness is 58.4 nm and the standard deviation of the thickness is an extremely uniform silver shell of only 7.9 nm. In addition, as in the concentration uniformity test, 50 AlNiCo-based magnetic particles were randomly selected and the thickness and thickness distribution of the silver shell formed through cross-sectional observation were measured. As a result, the average silver shell thickness of all the AlNiCo-based magnetic particles (in each of the magnetic particles) Silver shell average thickness) of 56.2 to 59.7 nm, and the standard deviation of the silver shell thickness (the standard deviation of the silver shell thickness in each of the magnetic particles) was in the range of 7.1 to 8.3 nm.

In addition, using a spectrophotometer (Carry 5000) and irradiating a 900 nm laser to measure the infrared reflectance of the magnetic particles produced, it was confirmed to have a reflectance of 64%.

In addition, as a result of measuring the brightness (L *) value of the CIELAB colorimeter using a colorimeter (Spectrophotometer CM-5), it was confirmed to have 78.

Using the AlNiCo-based magnetic particles prepared in Example 1, a security ink (hereinafter referred to as a hard magnetic ink) for oil price certificate was prepared. In detail, 18% by weight of the first varnish (construction chemistry, KR-KU), 14% by weight of the second varnish (construction chemistry, KR-KA), 10% by weight of the prepared AlNiCo-based magnetic particles, sieving pigment (Dongho Calcium, TL) -2000) 41% by weight, 6% by weight of mixed wax (Micro Powders, Polyfluo 540XF), 2% by weight of aliphatic hydrocarbons (SK chemicals, YK-D130), 2% by weight of solvent (diethylene glycol monobutyl ether), surfactant ( Hannonghwaseong, Koremul-263Na) After mixing with 5% by weight and 2% by weight of desiccant, it was introduced into a meat grinder and subjected to 4-5 times in the meat grinder to prepare a security ink.

As a paramagnetic ink, an ink was prepared with the same material and composition as the hard magnetic ink, except that 10% by weight of the magnetic pigment (BASF, 025) was mixed instead of 10% by weight of the AlNiCo-based magnetic particles prepared in Example 1 It was prepared in the same manner as a hard magnetic ink.

3 is a view showing an optical image, a soft magnetic image, a ferromagnetic image, and an infrared image observing the security elements produced by printing the manufactured hard magnetic ink and the paramagnetic ink.

As can be seen from the optical photograph of FIG. 3, in the case of the general magnetic particles, it has a dark color inherent to the magnetic particles, but it can be confirmed that the part in which the ink containing AlNiCo-based magnetic particles according to the present invention is printed is capable of implementing bright colors. have. In addition, as can be seen from the soft magnetic image obtained by taking the magnetic image in the soft magnetic mode using a magnetic image measuring device (G & D), the ink containing AlNiCo-based magnetic particles according to the present invention is a general soft magnetic pigment in the soft magnetic mode. It can be seen that it has substantially similar magnetic properties to practically indistinguishable. However, as can be seen from the hard magnetic image obtained by taking the magnetic image in the hard magnetic mode using the same magnetic image measuring device, the AlNiCo-based magnetic particles according to the present invention are stably detected in the hard magnetic mode and form a distinct image, It can be seen that the soft magnetic pigment is not detected. In addition, the AlNiCo-based magnetic particles according to the present invention, as can be seen from the infrared image taken using an infrared image measuring device (Foster & Freeman, VSC 4 PLUS), do not appear as an image due to the infrared reflection characteristics, but the general soft magnetic pigment is It can be seen that the image is formed by the infrared absorption characteristics.

As described above, in the present invention, it has been described by specific matters and limited embodiments and drawings, which are provided to help a more comprehensive understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention Various modifications and variations are possible from those skilled in the art to those skilled in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it will be said that not only the claims to be described later, but also all equivalent or equivalent modifications to the claims belong to the scope of the spirit of the present invention.

Claims (16)

A security ink composition comprising AlNiCo-based magnetic particles, varnish, pigment, surfactant, wax and solvent,
The AlNiCo-based magnetic particles include core particles containing Al, Ni, and Co; And an inorganic shell surrounding the core particles;
The core particles are ultra-fine particles having a particle size of D ₅₀ of 12 μm or less corresponding to 50% in the cumulative distribution of particle diameters of the core particles, and the security ink composition having the composition uniformity of Equations 1, 2, and 3 below.
Equation 1: 10 ≤ UNF (Al)
Equation 2: 10 ≤ UNF (Ni)
Equation 3: 10 ≤ UNF (Co)
(In Equation 1, UNF (Al) is the weight% composition basis, the average Al composition between core particles divided by the standard deviation of the Al composition, UNF (Ni) in Equation 2 is the weight% composition basis, the average Ni composition between the core particles It is the value divided by the standard deviation of the Ni composition, and UNF (Co) in Equation 3 is the weight% composition standard, and the average Co composition between core particles is divided by the standard deviation of the Co composition) According to claim 1,
5 to 15 wt% of the AlNiCo-based magnetic particles, 10 to 40 wt% of the varnish, 30 to 70 wt% of the pigment, 1 to 20 wt% of the surfactant, 1 to 15 wt% of the wax and 1 to 30 wt% of the solvent Security ink composition comprising a. According to claim 1,
The varnish includes any one or two or more selected from thermoplastic resins, thermosetting resins and photocurable resins,
The pigments are soluble azo pigment, insoluble azo pigment, phthalocyanine pigment, halogenated phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, isoindolin pigment, perylene pigment, perinone pigment, dioxazine pigment, anthraquinone pigment, Dianthraquinonyl pigment, anthrapyrimidine pigment, andanthrone pigment, indanthrone pigment, flavanthrone pigment, pyranthrone pigment, and diketopyrrolopyrrole pigment.
The surfactant includes any one or two or more selected from fluorinated surfactants, polymerizable fluorinated surfactants, siloxane surfactants, polymerizable siloxane surfactants, polyoxyethylene surfactants and derivatives thereof,
The wax is a security ink composition comprising any one or two or more selected from polyethylene wax, amide wax, erucamide wax, polypropylene wax, paraffin wax, Teflon and carnauba wax. According to claim 1,
Security ink composition further satisfying the following formulas 7 and 8.
Equation 7: 3 μm ≤ D ₅₀ ≤ 12 μm
Equation 8: 10 μm ≤ D ₉₀ ≤ 20 μm
(In Equation 7, D ₅₀ is the particle size corresponding to 50% in the cumulative distribution of the particle size of the core particle, and in Equation 8, D ₉₀ is the particle size corresponding to 90% in the cumulative distribution of the particle size of the core particle) According to claim 1,
The AlNiCo-based magnetic particles have a security ink composition having an infrared reflectance of 60% or more based on a wavelength of 900 nm. According to claim 1,
The hard magnetic particle is a security ink composition having an L * value of 60 or more measured by a colorimeter. According to claim 1,
The inorganic shell is a security ink composition comprising a metal shell satisfying the following formulas 9 and 10.
Equation 9: 50 nm ≤ t _m ≤ 100 nm
Equation 10: σ _t ≤ 30 nm
(In equation 9, t _m is the average thickness of the metal shell, and in equation 10, σ _t is the standard deviation of the metal shell thickness.) The method of claim 7,
The inorganic shell is a security ink composition further comprising a dielectric shell located on the lower or upper portion of the metal shell. The method of claim 8,
The dielectric shell is located under the metal shell,
The metal shell includes any one or two or more selected from copper, nickel, gold, platinum, silver, aluminum and chromium,
The dielectric shell is a security ink composition comprising any one or more selected from titanium oxide, silicon oxide, aluminum oxide, zinc oxide, zirconium oxide, calcium carbonate, magnesium fluoride and zinc sulfide. According to claim 1,
The saturation magnetization (Ms) of the magnetic particles is 50 to 150 emu / g, and the residual magnetization (Mr) is 10 to 40 emu / g. According to claim 1,
The coercive force of the magnetic particles is 100 to 500 Oe security ink composition. According to claim 1,
The core particle is a security ink composition further comprising one or two or more fourth elements selected from Cu, Ti, Fe and Si. The method of claim 12,
The core particle is a composition based on weight%, and a security ink composition having a value obtained by dividing an average fourth element composition between core particles by a standard deviation of the fourth element composition is 10 or more. According to claim 1,
The core particles further contain Ti, Fe and Cu, based on weight percent, Al 4 to 12%, Ni 10 to 20%, Co 15 to 25%, Ti 1 to 10%, Cu 0.5 to 5%, balance Fe And other inevitable impurities. According to claim 1,
Security ink composition used for printing intaglio ink. A price certificate printed with the security ink composition of any one of claims 1 to 15.

Images