KR101718505B1 - Method of manufacturing of magnetic particle for security ink and security ink using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing AlNiCo-based magnetic particles for security ink which includes core particles containing Al, Ni, and Co; and an inorganic shell covering at least a portion of the surface of the core particle. The method includes the steps of: a) dissolving a raw material of core particles and preparing spherical fine particles in a mixed spraying method; b) heat-treating the produced fine particles at 700C to 800C, and then sorting the particles to obtain core particles; and c) sequentially forming a dielectric shell and a metal shell on the core particle to produce a magnetic particle for security ink, where the core particles obtained after the step b) satisfy the following inequalities 1 to 3. [Inequality 1]3 m <= D_50 <= 9 m [Inequality 2]10 m <= D_90 <= 20 m [Inequality 3]10 kA/m <= Hc <= 50 kA/m In Inequality 1, D_ 50 is a particle size corresponding to 50% of the particle cumulative distribution of the core particles. In Inequality 2, D_ 90 is a particle size corresponding to 90% of the particle cumulative distribution of the core particles. In Inequality 3, Hc is a coercive force of the core particle.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing magnetic particles of AlNiCo for security ink, and a security ink using the same,

The present invention relates to a method of manufacturing AlNiCo-based magnetic particles for security ink and a security ink using the same, and more particularly, to a method of manufacturing a magnetic ink for security ink by forming spherical fine particles by a gas atomization method for maximizing security, A core shell structure in which the coercive force is controlled and the average particle diameter is controlled, and a security ink using the same.

The security material may be necessary in areas where forgery prevention is required. For example, in the field of security printing, security materials are used for certificates such as checks, stamps, gift certificates, stamps, and bonds.

Among the security materials, magnetic particles having a core shell structure formed by coating an inorganic material on a magnetic material are known. In order to brighten the dark color of the magnetic material, an inorganic material is coated, or a different kind of inorganic material (Korean Patent Publication No. 2013-0072444).

In recent years, studies have been made to maximize the security of security products using the security material. As a first step of the research, a method of making the coercive force and magnetization density of the magnetic particles have a specific region, more specifically, a method of mixing a soft magnetic particle having a relatively large coercive force and a soft magnetic particle having a relatively small coercive force, It is possible to maximize the security of the security product.

However, through the evolution of highly developed measuring equipment, if the security material has a simple pattern or if the coercive force difference of the incorporated magnetic particles is too large, it can be easily recognized from general equipment, so that the security material can be used as an expensive high- It is required to have a coercive force and a coercive force in a specific region so that it can be recognized only by the "expensive recognition equipment"

However, existing magnetic particles have the following problems in solving this problem. 1) If the magnetization density of the magnetic particles is too large or small, it is difficult to measure the intrinsic signals of the magnetic particles. 2) When the size of the magnetic particles is too large or small, it is difficult for the magnetic particles to effectively reflect sunlight, so that it is difficult to conceal the magnetic particles of dark colors originally, In addition, it can cause problems such as printing defects during the security printing process.

To solve this problem, it is possible to provide i) a method of crushing relatively large particles to a desired size, and ii) a method of producing relatively small nanoparticles by aggregation with a binder.

However, the pulverizing method of i) may cause the magnetic properties such as coercive force to be lowered when the magnetic particles are pulverized, and the method of agglomerating the binder of ii) has problems of swelling the binder when coagulated with the magnetic particles It is difficult to manufacture magnetic particles for security having a specific size and a specific shape.

In addition to the above two methods, the atomization method is known as a method of producing magnetic particles with a specific size. The atomization method is classified into gas spraying method, water dispersion method and mixed spraying method depending on the kind of the cooling medium. Generally, in the atomization method, the molten metal of an alloy is sprayed into a cooling medium through a nozzle or the like, and the molten metal is cooled by colliding the molten metal with the cooling medium, whereby the magnetic particles having a particle diameter of several tens or several hundreds of micrometers It is possible to manufacture.

However, since the water atomization process uses relatively low-cost water (H ₂ O) instead of gas or air as the main cooling medium, there is a great problem of oxidation of the powder produced. For this reason, it is used only in a limited amount of cases where oxidation problems can be solved by a substance having a low oxidation problem or by a post-treatment process.

In addition, since the inert gas (N ₂ , Ar, He) or air is used as a cooling medium in the gas atomization method, it is possible to manufacture a high-quality powder with less problems of oxidation and mixing of impurities in the production of powder, , There is a possibility of occurrence of fine segregation during the manufacturing process, and there is a technical difficulty in manufacturing magnetic particles having a specific shape (Japanese Patent No. 4055709).

Accordingly, the magnetic particles for a security ink according to the present invention are required to have a specific size and a specific shape capable of effectively reflecting sunlight and concealing dark-colored magnetic particles, It is required to have a coercive force and a magnetization density of the region to induce the improvement of the printing defective rate in the security printing process. Further, even when the raw material of the magnetic particles for the security ink is produced by the gas atomization method, Is required to be selected and formulated.

Korean Patent Publication No. 2013-0072444 Japanese Patent No. 4055709

The present invention relates to a core-shell type security ink for controlling the coercive force and controlling the average particle size to maximize security by manufacturing spherical fine particles by using a gas spraying method for raw materials including Al, Ni, and Co, A method of producing AlNiCo-based magnetic particles is provided.

In addition, the present invention provides a security ink for a liquid ink using a manufacturing method according to the present invention.

In order to accomplish the above object, the present invention provides a core particle comprising Al, Ni, and Co; And an inorganic shell covering at least a part of the surface of the core particle, the method comprising the steps of:

a) dissolving the raw material of the core particles and preparing spherical fine particles by gas spraying; b) subjecting the produced fine particles to heat treatment at 700 to 800 占 폚, and then sorting the particles to obtain core particles; And c) sequentially forming a dielectric shell and a metal shell on the core particles to produce magnetic particles for a security ink, wherein the core particles obtained after the step b) Method of producing AlNiCo-based magnetic particles for ink:

[Relation 1]

3 μm ≤ D ₅₀ ≤ 9 μm

[Relation 2]

10 μm ≤ D ₉₀ ≤ 20 μm

[Relation 3]

10 kA / m ≤ Hc ≤ 50 kA / m

[In the above relational expression 1, D ₅₀ is a particle size corresponding to 50% in the cumulative cumulative distribution of the particle diameter of the core particles,

In the above formula (2), D ₉₀ is a particle size corresponding to 90% of the particle cumulative distribution of the core particles,

In the above-mentioned relational expression 3, Hc is the coercive force of the core particle.

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, in the step a), the gas atomization method includes an inert gas, and the inert gas may be injected through the annular atomizing nozzle.

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, the gas spraying pressure may be 15 to 80 bar.

In the method for producing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, in the step (a), a method for producing AlNiCo-based magnetic particles for security ink satisfying the following relational expression 4:

[Relation 4]

0.1? LF? 10

[In the above equation 4, and _{LF = d m (M m /} M g) 1/2, d m represents the diameter (mm) of the melt orifices, M _m denotes a molten metal mass feed rate (g / s) , And M _g represents the gas mass feed rate (g / s).]

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, the core particles further include Cu, Si, Mn, Ti, and C, , Ni: 15 to 20%, Co: 21 to 27%, Cu: 0.5 to 5 percent, Si: 3 percent or less (0 percent excluded), Mn: 1 percent or less (0 percent excluded) C: 1% or less (without 0%), the balance Fe and other unavoidable impurities.

In the method for producing the AlNiCo-based magnetic particles for security ink according to the embodiment of the present invention, the following relation (5) can be satisfied during the heat treatment in step (b):

[Equation 5]

19600? LMP? 20700

In the above relation, LMP = T (logt _r + C) where T is temperature (K), t _r is time (hr), and C is a constant 20. [

In the method for producing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, the core particles have a saturation magnetization (Ms) of 80 to 180 emu / g and a remanent magnetization Mr of 8 to 45 emu / g Lt; / RTI &gt;

In the method of manufacturing the AlNiCo-based magnetic particles for security ink according to the embodiment of the present invention, in the step c), the magnetic particles may be selected from titanium dioxide, silicon dioxide, alumina, calcium carbonate, zirconium oxide, magnesium fluoride, A dielectric shell comprising at least one of the group consisting of zinc; And a metal shell comprising at least one of the group consisting of copper, nickel, gold, platinum, silver, aluminum and chromium.

According to another aspect of the present invention, there is provided a security ink for a liquid ink containing an AlNiCo magnetic particle, a varnish, a pigment, a surfactant, a wax, and a solvent for security ink using the above-described manufacturing method.

In the security ink for ink-to-be-marketed according to an embodiment of the present invention, the security ink may contain 5-15 wt% AlNiCo magnetic particles, 20-40 wt% varnish, 30-50 wt% pigment, 5-10 wt% Active agent, 1 to 10 wt% wax, and 2 to 10 wt% solvent.

The method of manufacturing AlNiCo-based magnetic particles for security ink according to the present invention has a specific size and a spherical shape capable of effectively reflecting sunlight to conceal dark-colored magnetic particles, and can be applied to expensive recognition equipment The security of the secure medium can be further improved.

In addition, the method of manufacturing AlNiCo-based magnetic particles for security ink according to the present invention has a coercive force and a coercive force in a specific area so that it can be recognized only by expensive recognition equipment, thereby improving the security of the security medium.

In addition, the method of manufacturing AlNiCo-based magnetic particles for security ink according to the present invention can produce a core shell structure that brightens the dark color of the magnetic powder, so that the magnetic particles can have high brightness and bright colors.

In addition, since the method of producing AlNiCo-based magnetic particles for security ink according to the present invention is made of spherical core particles, it is possible to coat the expensive inorganic shell with a smaller amount of the core particles having a lot of distortion, And the core particles can be controlled to a few micrometers, which is an effective method because the expensive inorganic shell can be coated in a smaller amount than the nano-sized core particles.

In addition, the security ink for oil markers employing the magnetic particles, which can be applied to the security ink and the oil grade certificate using the method of manufacturing AlNiCo-based magnetic particles for security ink of the present invention, improves the printing defect rate in the security printing process, There is an advantage that the physical properties of the ink can be easily controlled.

Further, the magnetic particles using the method for producing AlNiCo-based magnetic particles for security ink of the present invention exhibit hardness, and when distributed in a patterned shape together with the soft magnetic particles produced by the gas atomization method of the present invention, It is possible to maximize the security in the form of a binary number.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram showing a method for producing AlNiCo-based magnetic particles for security ink according to Example 1 of the present invention. FIG.
2 is an SEM photograph of core particles according to Example 1 of the present invention.
3 is an SEM photograph of the core particle according to Comparative Example 1 of the present invention.
4 is a graph showing the coercive force according to the heat treatment conditions of the present invention.

Hereinafter, the present invention will be described in detail. The following embodiments and drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. In addition, unless otherwise defined in the technical and scientific terms used herein, unless otherwise defined, the meaning of what is commonly understood by one of ordinary skill in the art to which this invention belongs is as follows, A description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

In describing the present invention, the term &quot; hard magnetism particle &quot; is difficult to magnetize, but it is difficult to demagnetize once it is magnetized. It has a higher coercive force (Hc) and remanent magnetization density (Mr) than soft magnetism particles it means. In the magnetic particles for a security ink according to the present invention, the hardness means that the coercive force is 10 to 50 kA / m.

In describing the present invention, the term "soft magnetic particle" means that it can be easily magnetized by a relatively weak magnetic field, and when the external magnetic field is removed, the magnetization rapidly disappears with time. In the magnetic particles for a security ink according to the present invention, the softness means that the coercive force is 1 to 10 kA / m (not including 10 kA / m).

In describing the present invention, the term "gas spraying method" may mean a process or a manufacturing method in which an inert gas or air is used as a cooling medium when the molten alloy is sprayed through a nozzle or the like. In the method for producing AlNiCo-based magnetic particles for security ink according to the present invention, the inert gas may be N ₂ , Ar, He, Ne, or a mixed gas thereof.

In describing the present invention, the term " spherical "may mean not only a purely symmetrical spherical shape but also an average value of the eccentricity defined by the following equation: 0 to 0.5:

[Equation 1]

[In the above equation (1), e is the eccentricity, a is the major axis of the spherical particle, and b is the minor axis of the spherical particle.

The Applicant has long been devoted to the type, composition and manufacturing method of magnetic particles for a long time in order to maximize the security of a security material for which forgery and falsification prevention is absolutely required. In particular, the raw material containing Al, Ni, and Co by the gas atomization process, a heat treatment step, and shell forming step was prepared the AlNiCo type magnetic particles of a core-shell structure and, as a result, the magnetic particles are formed in a spherical shape, D ₅₀ Is controlled at 3 to 9 占 퐉 and the coercive force is controlled at 10 to 50 kA / m, and thus the security material using the magnetic particles has been found to maximize security, and has been filed for the above manufacturing method.

The method of manufacturing AlNiCo-based magnetic particles for security ink according to the present invention is characterized in that, in order to improve the security of the magnetic particles, the magnetic particles are formed of a core shell, and the magnetic particles include Al, Ni, and Co Core particles; And an inorganic shell covering at least a part of the surface of the core particle.

The method of manufacturing the magnetic particles may further comprise the steps of: a) dissolving the raw material of the core particles and then preparing spherical fine particles by gas spraying; b) subjecting the produced fine particles to heat treatment at 700 to 800 占 폚, and then sorting the particles to obtain core particles; And c) sequentially forming a dielectric shell and a metal shell on the core particles to produce magnetic particles for a security ink, wherein the core particles obtained after the step b) satisfy the following relational formulas 1 to 3:

[Relation 1]

3 μm ≤ D ₅₀ ≤ 9 μm

[Relation 2]

10 μm ≤ D ₉₀ ≤ 20 μm

[Relation 3]

10 kA / m ≤ Hc ≤ 50 kA / m

[In the above relational expression 1, D ₅₀ is a particle size corresponding to 50% in the cumulative cumulative distribution of the particle diameter of the core particles,

In the above formula (2), D ₉₀ is a particle size corresponding to 90% of the particle cumulative distribution of the core particles,

In the above-mentioned relational expression 3, Hc is the coercive force of the core particle.

In detail, in the step a), the raw material of the core particles may be an alloy containing Al (aluminum), Ni (nickel), and Co (cobalt) excellent in coercive force, saturation magnetization and residual magnetization. As an example of a specific raw material for the core particles, the core particle may be a non-ferrous material including at least one selected from the group consisting of Al, Ni, Co, Cu (copper), Si (silicon), Mn (manganese), and Ti (titanium); Iron-containing iron (Fe); And other unavoidable impurities. However, the present invention is not limited thereto.

Further, the gas spraying method may be implemented by including an inert gas (N ₂ , Ar, He, air or a mixture thereof) as a cooling medium. In detail, the gas spraying method may spray the inert gas through a ring-shaped spray nozzle, but the present invention is not limited thereto. When the raw material of the dissolved core particles is injected through the injection nozzle, the core particles according to the present invention can be formed into a spherical shape, and can satisfy the relational expressions 1 to 2 described above.

Further, the spherical fine particles produced by the gas spraying method of the present invention can be heat-treated at 700 to 800 ° C. In detail, the saturation magnetization (Ms) of the fine particles produced by the gas atomization method may be about 100 to 200 emu / g, but the coercive force (Hc) may be 5 kA / m or less. Therefore, when the heat treatment is performed under the heat treatment temperature range, the coercive force is improved and the relation (3) is satisfied, so that it can be used for expensive recognition equipment capable of distinguishing between softness and lightness.

As a specific and non-limiting example, the heat treatment temperature is preferably 720 to 800 ° C, more preferably 750 to 800 ° C, which may be advantageous for achieving the object of the present invention.

Further, by selecting the particle size of the heat-treated spherical fine particles, the core particles satisfying the relational expressions 1 and 2 have a more uniform particle size distribution. In other words, since the method for manufacturing AlNiCo-based magnetic particles for security ink according to the present invention uses a process of sequentially forming the dielectric shell and the metal shell on the core particles, the result after sorting is immediately reflected in the blend design, Can be reduced.

Further, the dielectric particles and the metal shell are sequentially formed on the core particles obtained in the step (b), so that the core particles having a dark color can be concealed and the durability can be improved at the same time.

In addition, since the magnetic particles having the shells formed thereon satisfy the relational expression 3 described above, they have hard magnetic properties, and when the magnetic particles are used together with other magnetic particles having soft magnetic properties, the security of the security product can be improved.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a process diagram showing a method for producing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention. As shown in FIG. 1, the method for manufacturing the AlNiCo-based magnetic particles for security ink includes the steps of preparing an ingot (S100), preparing a molten metal (S200), a gas spraying step (S300), a heat treatment step (S400) (S500), and a core-shell magnetic particle production step (S600).

In detail, the ingot manufacturing step (S100) may be a step of manufacturing a master ingot, which is a raw material of core particles. The master ingot may include Al, Ni, Co, Cu, Si, Mn, Ti, Fe, and other inevitable impurities.

In a specific and non-limiting example, the master ingot is produced by compression-molding powders containing Al, Ni, Co, Cu, Si, Mn, Ti, and carbon steel to produce a shaped body, And then cooling it to produce an AlNiCo-based master ingot.

In addition, the carbon steel is a carbon steel having a carbon content of 0.15 to 0.3% based on the total weight of the carbon steel, which is effective in preventing oxidation in the heat treatment step, but the present invention is not limited to the content of the heavy carbon steel.

The molten metal manufacturing step (S200) may be a step of melting the master ingot produced in the ingot manufacturing step (S100) to produce a molten metal by high frequency dissolution. Specifically, the high-frequency dissolution may be a step of dissolving the master ingot in an inert atmosphere by induction heating for high frequency, but the present invention is not limited thereto.

As a specific and non-limiting example, the high-frequency dissolution temperature is in the range of 1300 to 1800 ° C for achieving the object of the present invention.

In the gas spraying step S300, when the molten metal produced in the molten metal producing step S200 is sprayed at a high pressure through an orifice, the above-mentioned cooling medium is sprayed at a high pressure from an annular injection nozzle to form a semi- As shown in Fig.

In addition, the atomizing nozzle may be installed in two or more. Specifically, the cooling medium may be sprayed through two or more spray nozzles independently of each other. The two or more spray nozzle outlets may be positioned apart from each other in the direction in which the molten metal falls. This can increase the cooling effect to reduce micro-segregation and obtain a more homogeneous microstructure. The average particle diameter of the fine particles produced in the gas spraying step (S300) can be satisfied by the above-described relational expressions 1 to 2, But the present invention is not limited thereto.

In addition, the semi-liquid phase particles produced in the gas spraying step (S300) can be treated by an additional cooling process. Specifically, the cooling step includes a first cooling step in which the semi-liquid phase particulate is cooled by colliding with a conical cooling roller rotating at a high speed, after the first cooling step, the particulates are separated from the outside of the conical cooling roller, And a fine particle discharging step of discharging fine particles cooled after the second cooling step to the outside by a spiral impeller installed on the lower side of the conical cooling roller However, the present invention is not limited thereto.

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, the spray pressure of the inert gas may be 15 to 80 bar. At this time, the core particles according to the present invention may be formed into a spherical shape, and the above-described relational expressions 1 and 2 may be satisfied.

In a specific and non-limiting example, the pressure of the inert gas is preferably 20 to 60 bar, more preferably 35 to 45 bar, but the present invention is not limited thereto.

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to an embodiment of the present invention, the above-mentioned molten metal and cooling medium in the gas spraying step (S300) may satisfy the following relational expression 4:

[Relation 4]

0.1? LF? 10

[In the above equation _{4, LF = d m (M} m / M g) 1/2 , and the process parameters to be defined by, d _m is the diameter M _m of the molten metal the orifice is the mass feed rate of M _g of the molten metal mass feed rate of the gas .]

That is, the relationship between the average particle size D of the fine particles by the gas spraying method and the mixed atomization (atomization) condition can satisfy the Lubanska equation defined by the following equation (1): &lt; EMI ID =

[Equation 1]

[In the above formula 1, K is an integer, d _m is the diameter of the melt flow (diameter of the melt orifices), ν _m is the same viscosity, ν _g of the molten metal has the same viscosity of the gas, W is V ² by the number of Weber ρ _m d _m / σ _m , where V is the flow velocity, ρ _m is the density of the molten metal, σ _m is the surface tension of the molten metal, M _m is the mass supply rate of the molten metal, and M _g is the mass supply rate of the gas. ]

According to the equation (1), the factor of decreasing the average particle diameter D means that the gas ejection speed or the amount thereof is increased, and it is understood that the diameter of the molten metal flow is greatly influenced. However, since the high-temperature molten metal has a high viscosity and a large surface tension, the diameter is not necessarily reduced to obtain fine particles. Therefore, in order to obtain particles having a uniform particle size, the diameter (dm) of the molten metal orifice, Mass feed rate (Mm), and gas mass feed rate (Mg).

In one embodiment of the present invention, when the gas spraying method is carried out under the process conditions of the above-mentioned Relational expression 4, the fine particles produced by the gas atomization method satisfy the relational expressions 1 and 2 described above, It is close to the sphere.

As a specific and non-limiting example, the LF of the above formula (4) is preferably from 0.5 to 8, more preferably from 1 to 5, for achieving the object of the present invention.

In addition, the heat treatment step (S400) of FIG. 1 may be a step of heat treating the fine particles produced in the gas spraying step (S300) into the heat treatment temperature range described above.

In detail, the fine particles may be formed into core particles by the heat treatment step (S400), and magnetic characteristics such as coercive force may be changed depending on the composition and composition of the core particles.

The method of measuring the composition and the composition of the core particles is not particularly limited and can be measured using a conventional component analysis measuring instrument. For example, Energy Dispersive X-ray Spectroscopy (EDS) and Inductively Coupled Plasma (ICP) may be used, but the present invention is not limited thereto.

Based on the composition and composition of the core particles measured by the measurement equipment, the core particles according to the present invention can be represented as follows.

Al (aluminum): 2 to 12 wt%

When the content of aluminum satisfies the above-mentioned category, the effect of preventing sintering is sufficient when the above-mentioned fine particles are heat-treated, so that the shape of the fine particles can be maintained. If the content of aluminum is out of the above range, it is necessary to carry out the annealing at a temperature higher than the above-mentioned heat treatment temperature, thereby increasing the amount of components that deteriorate the magnetic properties. If the content of aluminum is too high, the mechanical properties of the core particles deteriorate, which is not preferable from the viewpoint of cost. Accordingly, it is preferable that heat treatment in the above-mentioned aluminum range satisfies the above-described relational expressions 1 to 3, and it is preferable from the viewpoint of improving saturation magnetization and residual magnetization characteristics to be described later.

As a specific, non-limiting example, the content of aluminum is preferably 4 to 10% by weight, more preferably 5 to 8% by weight.

Ni (nickel): 15 to 20 wt%

When the content of nickel satisfies the above-mentioned category, it is preferable to increase the coercive force and residual magnetization, which are the magnetic characteristics of the present invention. If the content of nickel is out of the above range, the residual magnetization may be reduced and the coercive force may be remarkably deteriorated.

In a specific, non-limiting example, the nickel content is preferably 16 to 19 wt%, more preferably 17 to 18.5 wt%.

Co (cobalt): 21 to 27 wt%

When the content of the cobalt satisfies the above-mentioned range, it is advantageous in terms of increasing the coercive force, which is the magnetic property of the present invention, and is also effective in terms of the cost of the final product.

As a specific, non-limiting example, the content of cobalt is preferably 22 to 26% by weight, more preferably 23 to 25% by weight.

Cu (copper): 0.5 to 5 wt%

When the content of copper satisfies the above-mentioned category, the coercive force of the core particles according to the present invention can be maximized. If the content of copper exceeds 5% by weight, the coercive force may drop sharply.

In a specific, non-limiting example, the content of copper is preferably 1 to 4% by weight, more preferably 2 to 3% by weight.

Ti (titanium): 1 to 10 wt%

When the content of the titanium satisfies the above-mentioned category, it is preferable in terms of increasing the coercive force of the core particles according to the present invention. If the content of titanium deviates from the above range, the residual magnetization may be reduced.

As a specific, non-limiting example, the content of titanium is preferably 2 to 8 wt%, more preferably 3 to 6 wt%.

Mn (manganese): 1% by weight or less (excluding 0% by weight)

When the content of manganese satisfies the above-mentioned category, the strength and entrapping property of the AlNiCo-based alloy can be improved. If the content of manganese exceeds 1% by weight, it is likely to be oxidized during the execution of the gas atomization method described above, and the oxygen content in the metal powder (fine particles) becomes large. Therefore, pore generation, It may cause deterioration.

Si (silicon): 1% by weight or less (excluding 0% by weight)

The silicon is preferably added in an amount of 0.1% or more for deoxidation in the above-described melt-making step (S200) and for maintaining the stable shape of the fine particles in the mixing spraying step (S300). However, It is preferably 1% by weight or less.

Particularly, even when the raw material of the magnetic particles for security ink having the above composition is produced by the gas atomization method, the coercive force and the magnetization density are not changed as the size is reduced, and the magnetic properties of the magnetic particles Can be further improved.

That is, when the heat treatment step S400 satisfies the following relational expression 5, the coercive force of the relational expression 3 described above is improved, and the magnetic particles manufactured from the magnetic particles are applied to expensive security recognition equipment, thereby improving the security:

[Equation 5]

19600? LMP? 20700

In the above relation, LMP = T (logt _r + C) where T is temperature (K), t _r is time (hr), and C is a constant 20. [

In detail, in the above-mentioned formula (5), LMP is a heat treatment parameter and t _r means a holding time at the heat treatment temperature (T).

The reason why the LMP is set to 19600 or more and 20700 or less in accordance with the heat treatment temperature (T) and the time (t _r ) is that if the LMP is out of the above range, mechanical strength is insufficient and the coercive force Phase transition in the AlNiCo system phase diagram may occur. Therefore, the present invention is not limited to the LMP category, although it is not preferable from the viewpoint of magnetic property and shape retention.

Thus, the coercive force of the AlNiCo-based magnetic particles for security ink according to the present invention is not particularly limited, but may be preferably 15 to 50 kA / m, more preferably 20 to 45 kA / m.

In the method of manufacturing AlNiCo-based magnetic particles for security ink according to the present invention, the saturation magnetization (Ms) of the core particles produced by the heat treatment step (S400) may be 80 to 180 emu / g, May be 90 to 160 emu / g, and more preferably 100 to 150 emu / g, but the present invention is not limited thereto. For example, when the core satisfies the category of saturation magnetization, the magnetic signal of the magnetic particles according to the present invention can be detected by expensive recognition equipment.

Particularly, in the case where the magnetic signal including the hard magnetic particles and the soft magnetic particles are mixed with the security ink and then the magnetic signal is discriminated by the expensive recognition device, the magnetic particles including the saturated magnetization are classified into the soft magnetic particles The security characteristic of the security ink can be improved.

Further, in the magnetic particles for a security ink according to an embodiment of the present invention, the residual magnetization (Mr) of the core may be 8 to 45 emu / g, preferably 10 to 40 emu / g, May be 20 to 30 emu / g, but the present invention is not limited thereto. For example, if the core satisfies both the category of saturation magnetization (Ms) and the category of remanence magnetization (Mr) simultaneously, the discrimination probability of soft magnetic particles by expensive recognition equipment can be maximized.

In addition, the step of obtaining the core (S500) of FIG. 1 may be a step of selecting the particles produced in the heat treatment step (S400) to obtain a core.

In detail, the particle size selection at the step S500 of obtaining the core may include dry or wet classification of the particles produced in the heat treatment step S400. As a result, the particle size distribution is narrower than the relational expressions 1 and 2 described above And it is possible to prevent a difficulty such as a printing failure which may occur in a secure printing process, but the present invention is not limited thereto.

Further, in the method of manufacturing magnetic particles for security ink according to an embodiment of the present invention, after the step of obtaining the core (S500), the method may further include a step of injecting a dispersant into which the dispersant is injected.

Specifically, the dispersing agent is an inorganic compound composed of at least one or more of silicon, aluminum, and iron; And an organic compound composed of at least one of hydrogen, oxygen, and nitrogen.

As a specific, non-limiting example, the dispersant may comprise at least one of a silanol-based polymer, a siloxane-based polymer, and a silane-based polymer.

In addition, the dispersant may be 0.1 to 10 parts by weight based on 100 parts by weight of the core, and may be a hydrophilic polymer containing a silanol group, but the present invention is not limited thereto.

If the core according to the present invention is manufactured including the above-mentioned dispersant injecting step, the monodispersibility of the core can be improved, and the magnetic particles having a core shell structure with improved durability can be produced.

In the method of manufacturing magnetic particles for security ink according to an embodiment of the present invention, the core-shell magnetic particle manufacturing step (S600) may be performed after the core obtaining step (S500).

In more detail, the core-shell magnetic particle production step (S600) may be a step of sequentially forming a dielectric shell and a metal shell on the core particles obtained in the step (S500) of obtaining the core to produce magnetic particles.

For example, the magnetic particle production step (S600) may include: k1) applying a paste or a solution containing a dielectric precursor to the core particles to form a dielectric shell; k2) applying a paste or solution containing a metal precursor to the dielectric shell To form a metal shell; and k3) drying the coating containing the dielectric shell and the metal shell to form an inorganic shell disposed outside the core.

As a specific, non-limiting example, the dielectric precursor is preferably one or more selected from titanium dioxide precursors, silicon dioxide precursors, alumina precursors, calcium carbonate precursors, zirconium oxide precursors, magnesium fluoride precursors, zinc oxide precursors and zinc sulfide precursors . The metal precursor is preferably at least one selected from a copper precursor, a nickel precursor, a gold precursor, a platinum precursor, a silver precursor, an aluminum precursor, and a chromium precursor.

In addition, the pH during the k1) and / or k2) may be 7 to 10. This may be more effective in uniformly applying the precursor to the core according to the present invention to form a shell of uniform thickness.

In the step k3), the drying temperature may be 40 to 70 ° C, and the drying time may be 1 to 24 hours. However, the present invention is not limited thereto.

Also, the paste or solution comprising the dielectric precursor and the metal precursor may include polar and nonpolar solvents, which may include methanol, ethanol, distilled water, etc., and the nonpolar solvent may include toluene, benzene, minerals Oils, and the like.

In addition, the paste or solution may further comprise an additive. For example, sugars, salts and the like are preferable as additives. More specifically, the saccharide may be at least one selected from monosaccharides, glucose, fructose, galactose, and the like, and the salts may be selected from the group consisting of sodium chloride, potassium chloride, magnesium chloride At least one selected from sodium sulfate, magnesium sulfate, sodium tartrates, potassium tartrates, potassium sodium tartrate, calcium tartrate, stearyl tartrate and the like. It can be one.

In addition, the present invention provides a security ink for a liquid ink using the above-described method for producing AlNiCo-based magnetic particles for security ink.

In the security ink for ink-to-be-marketed according to an embodiment of the present invention, the security ink may contain AlNiCo-based magnetic particles, varnish, pigment, surfactant, wax, and solvent for the security ink described above.

In detail, the security ink comprises 5 to 15 wt% AlNiCo magnetic particles, 20 to 40 wt% varnish, 30 to 50 wt% pigment, 5 to 10 wt% surfactant, 1 to 10 wt% wax, and 2 to 10 wt % Solvent.

For example, the varnish may be a thermoplastic resin, a thermosetting resin, or a photo-curable resin, and is not limited to any kind as long as it is soluble in an organic solvent. Examples of the varnish which can be used in the present invention include thermoplastic resins such as petroleum resin, casein, shellac, rosin-modified maleic resin, rosin-modified phenolic resin, nitrocellulose, cellulose acetate butyrate, cyclized rubber, chlorinated rubber, An epoxy resin, a vinyl resin, a vinyl chloride resin, a vinylidene chloride resin, a vinyl chloride acetate resin, an ethylene vinyl acetate resin, an acrylic resin, a methacrylic resin, an acrylic resin, a methacrylic resin, a phenol resin, an alkyd resin, a polyester resin, an unsaturated polyester resin, , Polyurethane resin, silicone resin, fluorine resin, drying oil, synthetic drying oil, styrene-maleic acid resin, styrene-acrylic resin, polyamide resin, or butyral resin. Examples of the thermosetting resin include an epoxy resin, a phenol resin, a benzoguanamine resin, a melamine resin, and a urea resin. As the photo-curing 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, (Meth) acryloyl group, or a styryl group is introduced into the linear polymer. The linear polymer containing an acid anhydride such as a styrene-maleic anhydride copolymer or an alpha -olefin-maleic anhydride copolymer may be copolymerized with a (meth) acrylic compound having a hydroxyl group such as hydroxyalkyl (meth) It is also possible to use an esterified product.

The pigment is not particularly limited, and examples thereof include pigments such as soluble azo pigments, insoluble azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindolin pigments, perylene pigments, , Dioxazine pigments, anthraquinone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, pyranthrone pigments, and diketopyrrolopyrrole pigments. Pigment Blue 15, Pigment Blue 15: 1, Pigment Blue 15: 3, Pigment Blue 15: 4, Pigment Blue 15: 6, Pigment Blue 15: 22, Pigment Blue 60, or Pigment Blue 64;

Pigment Green 7, Pigment Green 36, or Pigment Green 58;

Pigment Red 9, Pigment Red 48, Pigment Red 49, Pigment Red 52, Pigment Red 53, Pigment Red 57, Pigment Red 97, Pigment Red 122, Pigment Red 123, Pigment Red 144, Pigment Red 147, Pigment Red 166, Pigment Red 166, Pigment Red 168, Pigment Red 177, Pigment Red 178, Pigment Red 179, Pigment Red 180, Pigment Red 185, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Red 215, Pigment Red 216, Pigment Red 217, Pigment Red 220, Pigment Red 221, Pigment Red 223, Pigment Red 224, Pigment Red 226, Pigment Red 227, Pigment Red 228, Pigment Red 238, Pigment Red 240, Pigment Red 242, Pigment Red 254, or Pigment Red 255;

Violet pigments such as Pigment Violet 19, Pigment Violet 23, Pigment Violet 29, Pigment Violet 30, Pigment Violet 37, Pigment Violet 40, or Pigment Violet 50;

Pigment Yellow 13, Pigment Yellow 13, Pigment Yellow 13, Pigment Yellow 17, Pigment Yellow 20, Pigment Yellow 24, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 86, Pigment Yellow 93, Pigment Yellow 94, Pigment Yellow 95, Pigment Yellow 109, Pigment Yellow 110, Pigment Yellow 117, Pigment Yellow 120, Pigment Yellow 125, Pigment Yellow 128, Pigment Yellow 137, Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 147, Pigment Yellow 148, Pigment Yellow 150, Pigment Yellow 151, Pigment Yellow 153, Pigment Yellow 154, Pigment Yellow 155, Pigment Yellow 166, Pigment Yellow 168, Yellow pigments such as Pigment Yellow 180, Pigment Yellow 185, or Pigment Yellow 213;

Pigment Orange 13, Pigment Orange 36, Pigment Orange 37, Pigment Orange 38, Pigment Orange 43, Pigment Orange 51, Pigment Orange 55, Pigment Orange 59, Pigment Orange 61, Pigment Orange 64, Pigment Orange 71, or Pigment Orange 74; or,

Pigment Brown 23, Pigment Brown 25, Pigment Brown 26, and the like.

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

The wax is not limited to a powder type as long as it can reduce the tack of the resin. Examples of the wax include polyethylene wax, amide wax, erucamide wax, polypropylene wax, paraffin wax, Teflon Carnauba wax, and the like, but is not limited thereto.

The solvent is not limited to any kind as long as it is a general organic solvent capable of uniformly mixing substances such as wax, pigment, and varnish. Examples of usable solvents 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 monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether acetate, and the like.

In the security ink for ink-to-be-marketed according to an embodiment of the present invention, the absorption induction of the AlNiCo-based magnetic particles may be 5 to 50. In the case of manufacturing the ink using the magnetic particles within the above-mentioned range, the suction induction of the pigment is lowered and the physical properties of the ink can be easily controlled.

The present invention also provides a first security ink composition comprising the above-mentioned AlNiCo-based magnetic particles for security ink (hereinafter referred to as first magnetic particles); And a second security ink composition comprising magnetic particles (hereinafter referred to as second magnetic particles) produced through the above-described melt manufacturing step (S200).

In detail, the second magnetic particles may mean the soft magnetic particles described above.

In addition, the first security ink composition and the second security ink composition may be similar or identical to each other independently of the composition of the security ink for a cash register.

In the security ink cartridge according to an embodiment of the present invention, the first security ink composition and the second security ink composition may be characterized by satisfying the following relational expression (6).

[Relation 6]

1.5? Q? 50, q = q1 / q2

Q1 is the coercive force of the first security ink composition, and q2 is the coercive force of the second security ink composition.

In addition, the present invention can provide the security patterned securities for security with the first security ink composition and the second security ink composition.

In the security certificate for security according to an embodiment of the present invention, the first security ink composition and the second security ink composition may satisfy the relationship (6).

Thus, the oil price certificate using the security ink according to the present invention is separated from the soft magnetic particles by expensive recognition equipment and distributed in a patterned shape, so that the security certificate of the oil price certificate can be improved, that is, Security can be maximized.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1

The ingot, which is a raw material of the core particles, conformed to the composition listed in Table 1, and 200 g of the ingot was placed in a crucible heated by a high-frequency generator and maintained at a temperature of 1650 ° C. At this time, the ingot was made of molten metal, and the molten metal was poured through a orifice on a rotating disk placed in a vacuum atomization confinement, and the rotation speed of the rotating disk was 30,000 rpm.

element C Si Mn Ni Al Cu Co Ti N O Fe content
(weight%) 0.023 0.32 0.05 17.63 6.61 2.50 24.07 4.24 0.005 0.18 Remainder

The molten metal was separated by the centrifugal force of the rotating disk and formed fine particles which were directed to the wall surface of the conformant through the cooling medium. The cooling medium was argon gas, and the argon gas was sprayed through the annular spray nozzle at 30 bar. Also, at the time of spraying, the diameter of the injection nozzle was 2.3 mm, and the LF parameter of the above-mentioned Relation 4 was 5. [

The sprayed fine particles were cooled by being blown against a cooling roller and discharged by a helical impeller installed at the lower part of the cooling roller, and spherical fine particles were produced.

The discharged fine particles were heat-treated at 750 ° C in an argon gas atmosphere. During the heat treatment, the LMP parameter of the above-mentioned formula 5 was 19664.

After the heat treatment, the obtained particles were sieved through a 500-mesh sieve to obtain core particles according to the present invention. The yield of the core particles satisfying the above-mentioned relational expressions 1 and 2 was 60% as calculated by the following relational expression 6:

[Relation 6]

(%) = (A2 / A1) x 100

[In the above relational expression 6, A1 is the total weight of the particles obtained after the heat treatment, and A2 is the total weight of the particles obtained after the sieving.

Thereafter, the core was separated from the magnet, washed twice with ethanol, and dried at 60 ° C. The average particle size of the obtained core was measured using a particle size analyzer (Beckman, Coulter Multisizer 3). The results are shown in Table 2.

The coercive force, saturation magnetization (Ms) and residual magnetization (Mr) of the core were measured using a VSM (vibrating sample magnetometer, Lakeshore, 7400 series).

The washed core was charged with 1 g of the core powder, 1 ml of TBOT (tetrabuthoxy titanium) (Aldrich), 1 ml of distilled water, 170 ml of ethanol, stirred at a temperature of 85 ° C for 2 hours at a rotating speed of 300 rpm , And the surface of the core was coated with a titanium oxide layer. The core particle powder coated with titanium oxide was separated by a magnet, washed twice with ethanol, and then dried.

Thereafter, 70 g of glucose and 5 g of potassium tartrate were dissolved in 800 ml of distilled water to prepare a reducing solution. Subsequently, 10 g of sodium hydroxide (NaOH), 86 ml of ammonium hydroxide (NH ₄ OH) and 45 g of silver nitrate (AgNO ₃ ) were added to the reducing solution and stirred at 300 rpm for 30 minutes to obtain a colorless transparent silver carboxylate Solution.

The silver complex solution, 80 g of the core coated with the titanium oxide layer and 2.4 L of distilled water were further mixed and stirred. The agitation was carried out at a speed of 300 rpm for 1 hour to prepare silver-coated core-shell magnetic particles. Then, the core-shell magnetic particles were separated by a magnet, washed twice with ethanol, and dried at 60 ° C.

Example 2

Except that the argon gas was sprayed at 45 bar, the injection nozzle had a diameter of 1 mm, and the LF parameter was 1. The yield of the core particles prepared in Example 2 was 80%, and the size distribution of the core particles was more uniform than in Example 1.

Example 3

The discharged fine particles were subjected to heat treatment at 800 ° C and the same as in Example 1, except that the LMP was 20625 during the heat treatment. The core particles produced by Example 3 had a coercive force of about 252% higher than that of Example 1. [

Comparative Example 1

The same procedure as in Example 1 was carried out except that the cooling medium was used as liquid H ₂ O. [ As shown in FIG. 3, the core particles produced by Comparative Example 1 appeared amorphous or random, and many fine segregations were observed, and problems such as a very wide distribution of particle diameters occurred.

Comparative Example 2

Example 1 was carried out in the same manner as Example 1 except that the diameter of the melt orifice was 50% of that of Example 1, the diameter of the injection nozzle was 0.5 mm and the LF parameter was 0.05. However, Irregularly poured, fine segregation occurred a lot, and the particle size distribution was very broad compared to Example 1 and fine particles having a size of 1 μm or less were produced.

Comparative Example 3

Example 1 was repeated except that the diameter of the melt orifice was 200% of the diameter of Example 1, the diameter of the injection nozzle was 5 mm and the LF parameter was 12. The core particles prepared in Comparative Example 3 had many sphere shapes and nonuniform particle size distribution. In addition, the yield of the core particles according to the above-mentioned relational expression 6 was extremely low at 30%.

Comparative Example 4

The discharged fine particles were subjected to a heat treatment at 690 ° C and the same as in Example 1, except that the LMP was 19167 during the heat treatment. The coercive force of the core particles prepared in Comparative Example 3 was greatly reduced to about 38% as compared with Example 1.

Comparative Example 5

The discharged fine particles were subjected to a heat treatment at 850 ° C and the same as in Example 1, except that the LMP was 21137 during the heat treatment. The coercive force of the core particle prepared in Comparative Example 4 was remarkably reduced to about 34% as compared with that in Example 1.

Comparative Example 3

For inductance measurement, commercially available Fe ₃ O ₄ (Lanxess , E8840). Unlike the AlNiCo-based magnetic particles of the core shell structure according to Example 1, the Fe ₃ O ₄ Had no shells and were magnetic particles with an aspect ratio of about 10 and an average major axis length of about 500 nm.

Particle size
( μm ) Example  One
(Number, % ) Example  2
(Number, % ) Comparative Example  3
(Number, % ) One 5.065 1.585 - 3 20.135 21.256 0.358 5 41.256 55.860 1.585 8 61.648 95.852 5.482 12 78.886 98.998 7.580 16 86.145 100 10.468 20 95.864 - 20.874 24 99.984 - 41.846 28 100 - 65.585

Saturation magnetization
(emu / g) Residual magnetization
(emu / g) Coercivity
(kA / m) Example  One 121.54 10.62 16.21 Example  2 122.35 12.35 18.56 Example  3 124.66 23.36 40.86 Comparative Example  4 130.44 4.77 6.26 Comparative Example  5 126.62 4.16 5.53

Example 4

The security ink for oil-for-degaussing was prepared using the magnetic particles prepared in Example 3, and the ingredients were mixed in the ingredients and contents shown in Table 4, and the mixture was put into a kneader and kneaded four to five times in the kneader. To prepare a composition suitable for the printability of the security ink.

Ink composition weight% First varnish
(Construction Chemicals, KR-KU) 18 Second varnish
(Construction Chemicals, KR-KA) 14 Colored pigment
(Clariant, FBB02) 5 Extender pigment
(Dong Ho Calcium, TL-2000) 34 AlNiCo-based magnetic particles 10 Mixed wax
(Micro Powders, Polyfluo 540XF) 8 Aliphatic hydrocarbon
(SK chemicals, YK-D130) 2 solvent
(Diethylene glycol monobutyl ether) 2 Surfactants
(Korenul-263Na) 5 drier 2 Sum 100

Referring to FIG. 2, the surface of AlNiCo-based magnetic particles for security ink according to Example 1 is measured with an SEM (FEI company, Magellan 400). As shown in FIG. 2, the AlNiCo-based magnetic particles for security ink according to the present invention are prepared by sequentially forming a dielectric shell containing TiO ₂ and a metal shell containing Ag on the surface of core particles, . The average particle diameter of the magnetic particles was found to be about 3.5 μm.

Referring to FIG. 4, the graphs of the coercive force according to the heat treatment conditions including the above-described embodiments and the comparative examples are shown. As shown in FIG. 4, when the LPM value is set to 19664 to 20625, the coercive force can have a very suitable value applicable to expensive recognition equipment. In detail, when the LMP is 19664, the coercive force is 16.21 kA / m and when the LMP is 20625, the coercive force is 39.86 kA / m. Also, the coercive force by the LMP value in the above-mentioned category was included in the above-mentioned Relation 3.

The results of the inductance measurements of Example 3 and Comparative Example 6 are shown in Table 5 below. According to the results shown in Table 5, it can be seen that the absorption induction of AlNiCo-based magnetic particles for security ink according to the present invention is 16.66. As a result, the AlNiCo-based magnetic particles for security inks of the present invention are low in the absorption induction, so that the compatibility can be improved, the viscosity can be easily controlled, the printability can be improved, and the smoothness can be improved .

sample Amount of sample
(g) Amount of oil used
(g) Suction induction (g / 100 g) Example 3 1.08 0.18 16.66 Comparative Example 6 1.02 0.72 70.58

In addition, the oil absorption measurement was performed by a general test method for measuring the oil absorption amount of pigments and extender pigments as a part of Korean Industrial Standard KS M ISO 787. Oil absorption value is the amount of refined linseed oil that is absorbed into pigment or sieving pigment samples under defined conditions and expresses the amount of oil per gram of sample in grams (g).

Further, the lightness of the magnetic particles including up to the silver layer obtained according to the above embodiments (Examples 1 to 3) was evaluated by measuring the lightness at the values of L, a, and b of the colorimeter. As a result, Respectively.

The magnetic particles according to Example 3 and the magnetic particles according to Comparative Example 6 described above were used to evaluate the printability according to the average particle diameter. The results are shown in Table 6. In Comparative Example 6 of the present invention, since the ink absorption was high, the viscosity of the ink was high, and thus printing failure occurred.

sample Average particle diameter D ₅₀  (μm) content
(g) Whether to print Example 3 5 5 Good Comparative Example 6 0.5 5 Bad

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (9)

Core particles containing Al, Ni, and Co; And an inorganic shell covering at least a part of the surface of the core particle, the method comprising the steps of:
a) dissolving the raw material of the core particles and preparing spherical fine particles by gas spraying;
b) subjecting the produced fine particles to heat treatment at 700 to 800 占 폚, and then sorting the particles to obtain core particles; And
c) sequentially forming a dielectric shell and a metal shell on the core particles to produce magnetic particles for security ink,
The core particle obtained after the step (b) satisfies the following relational equations (1) to (3): (1) A method for producing an AlNiCo-
[Relation 1]
3 μm ≤ D ₅₀ ≤ 9 μm
[Relation 2]
10 μm ≤ D ₉₀ ≤ 20 μm
[Relation 3]
10 kA / m ≤ Hc ≤ 50 kA / m
[In the above relational expression 1, D ₅₀ is a particle size corresponding to 50% in the cumulative cumulative distribution of the particle diameter of the core particles,
In the above formula (2), D ₉₀ is a particle size corresponding to 90% of the particle cumulative distribution of the core particles,
In the above-mentioned relational expression 3, Hc is the coercive force of the core particle.
The method according to claim 1,
In the step a)
Wherein the gas spraying method comprises an inert gas, and the inert gas is injected through an annular injection nozzle.
3. The method of claim 2,
Wherein the spray pressure of the gas is from 15 to 80 bar. &Lt; RTI ID = 0.0 &gt; 15. &lt; / RTI &gt;
The method of claim 3,
A method for producing an AlNiCo-based magnetic particle for security ink satisfying the following relational expression (4) in the step (a)
[Relation 4]
0.1? LF? 10
[In the above equation 4, and _{LF = d m (M m /} M g) 1/2, d m represents the diameter (mm) of the melt orifices, M _m denotes a molten metal mass feed rate (g / s) , And M _g represents the gas mass feed rate (g / s).]
The method according to claim 1,
Wherein the core particles further comprise Cu, Si, Mn, Ti, and C,
The steel sheet according to any one of claims 1 to 3, wherein the steel sheet has a composition of Al: 2 to 12%, Ni: 15 to 20%, Co: 21 to 27%, Cu: 0.5 to 5% %, Ti: 1 to 10%, C: 1% or less (0% inclusive), the balance Fe and other unavoidable impurities.
6. The method of claim 5,
A method for producing an AlNiCo-based magnetic particle for security ink satisfying the following relational expression (5) at the time of heat treatment in the step (b)
[Equation 5]
19600? LMP? 20700
In the above relation, LMP = T (logt _r + C) where T is temperature (K), t _r is time (hr), and C is a constant 20. [
The method according to claim 1,
Wherein the core particles have a saturation magnetization (Ms) of 80 to 180 emu / g and a residual magnetization (Mr) of 8 to 45 emu / g.
The method according to claim 1,
In the step c)
The magnetic particles
A dielectric shell comprising at least one member selected from the group consisting of titanium dioxide, silicon dioxide, alumina, calcium carbonate, zirconium oxide, magnesium fluoride, zinc oxide and zinc sulfide; And
Wherein the metal shell comprises at least one metal selected from the group consisting of copper, nickel, gold, platinum, silver, aluminum and chromium.
A security ink for a liquid ink containing an AlNiCo-based magnetic particle, a varnish, a pigment, a surfactant, a wax, and a solvent for security ink prepared according to any one of claims 1 to 8.

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