KR101738918B1 - Method of fabricating Quantum Dot - Google Patents

Abstract

Provided is a method for fabricating quantum dots in a core-shell structure. The method comprises the following steps: preparing a first solution including a first metal; preparing a second solution including a chalcogen element; preparing a third solution including a second metal; mixing the first solution, the second solution and the third solution; and supplying the mixed solution into a reactor. The first metal and the second metal are different group 12 elements. The mixed solution comprises a crystal growth regulator including an amine group.

Description

Method of Fabricating Quantum Dot [

The present invention relates to a method of manufacturing a quantum dot, and more particularly to a method of manufacturing a quantum dot having a core shell structure.

The quantum dot is a material composed of spherical semiconductor nanoparticles or capable of releasing various spectra by controlling the size of quantum dots, and capable of emitting light at various wavelengths as well as in the visible light region. Due to these characteristics, quantum dots are not only spotlighted as materials capable of producing various colors in LEDs, displays, etc., but also various studies are being conducted for application to solar cells, bio-imaging, light emitting diodes and photodetectors.

In order to improve the safety and quantum efficiency of such quantum dots, a core shell (core / shell) type quantum dot has been proposed. In the case of a core-shell type quantum dot, quantum efficiency can be improved by 30 to 50% by applying a material having a different band gap to a core and a shell. However, conventionally, in order to manufacture a core-shell quantum dot, a core is first formed by a wet chemical method, and after the particles are washed, a shell is formed by a wet chemical method, so that the process is complicated and the production cost is high , And various studies have been carried out to improve this.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a quantum dot having a simplified manufacturing process.

Another aspect of the present invention is to provide a method of manufacturing a quantum dot having a reduced production cost.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problems, the present invention provides a method of manufacturing a quantum dot of a core shell structure.

According to one embodiment, a method of making a quantum dot comprises the steps of: preparing a first aqueous solution comprising a first metal, producing a second aqueous solution comprising a chalcogen element, forming a third aqueous solution comprising a second metal Mixing the first aqueous solution, the second aqueous solution and the third aqueous solution, and supplying the mixed solution to the reactor, wherein the first metal and the second metal are different from each other in group 12 Element, and the mixed solution may include a crystal growth regulator containing an amine group.

According to one embodiment, the step of supplying the mixed solution to the reactor may include gradually increasing the concentration of the second metal.

According to one embodiment, the step of supplying the mixed solution to the reactor may be performed at a reaction temperature of 150 to 330 ° C.

According to one embodiment, the mixed solution may be supplied at a flow rate of 50 to 600 μl / min.

According to one embodiment, the concentration ratio of the second metal to the concentration of the first metal in the mixed solution may be 0.2 or less.

According to one embodiment, mixing the first aqueous solution, the second aqueous solution and the third aqueous solution comprises: mixing the first aqueous solution and the second aqueous solution; And mixing the second aqueous solution and the third aqueous solution, wherein the step of supplying the mixed solution to the reactor includes supplying a mixed solution of the first aqueous solution and the second aqueous solution to the reactor, And a step of supplying a mixed solution of the aqueous solution and the third aqueous solution to the reactor in sequence.

According to the embodiment of the present invention, when an additive including an amine group capable of controlling the growth rate of the core is added to an aqueous solution to form quantum dots of the core shell structure, a process of washing the core particles formed before forming the shell is performed The quantum dots of the core shell structure can be continuously formed in the reactor without the need for the quantum dots, thereby simplifying the manufacturing process of the quantum dots with improved quantum efficiency and reducing the manufacturing cost.

FIG. 1 is a flowchart illustrating a method for fabricating a quantum dot according to an embodiment of the present invention.
2 is an on-line UV analysis graph for quantum dots prepared at a flow rate of the mixed solution exceeding 600 / / min.
FIG. 3 is a graph showing the quantum yield and the photoluminescence peak according to the reaction temperature prepared according to the method of manufacturing a quantum dot according to the present invention.
4 is a schematic diagram of an apparatus for manufacturing quantum dots according to a method for manufacturing quantum dots according to an embodiment of the present invention.
FIG. 5 is a photograph of a reaction solution according to a flow rate of a mixed solution prepared according to the method of manufacturing a quantum dot according to the present invention.
6 is a photograph of a reaction solution according to a reaction temperature prepared according to the method for preparing a quantum dot according to the present invention.
7 is a photograph of a reaction solution prepared at a reaction temperature of 230 ° C or lower according to the method of the present invention.
8 to 9 are photographs of a reaction solution according to the concentration of the second metal according to the method of manufacturing a quantum dot according to the present invention.
10 is a photograph of a reaction solution to which octylamine is added as a crystal growth regulator according to the method of manufacturing a quantum dot according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content. Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof. In addition, various numerical ranges described below are interpreted to include numerical values substantially within the numerical range.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 1 is a flowchart illustrating a method for fabricating a quantum dot according to an embodiment of the present invention.

Referring to FIG. 1, a first aqueous solution containing a first metal, a second aqueous solution containing a chalcogen element, and a third aqueous solution containing a second metal are prepared to form a mixed solution (S10).

The first aqueous solution may be prepared by mixing a first metal-containing compound with an organic solvent. The first aqueous solution may be prepared by adding the first metal-containing compound to the organic solvent and stirring at 100 to 200 ° C. When stirring, a purge gas can be injected. The purge gas may be an inert gas. For example, the purge gas may be argon. The stirring process may be carried out for about 30 minutes to 2 hours, preferably for 1 hour.

The first metal may be one of Group 12 elements. For example, the first may be a first metal is cadmium, the first metal-containing compound is cadmium acetate (Cd (CH ₃ COO) ₂ H ₂ O).

The organic solvent may be hexadecylamine, trioctylamine, octadecene, octadecane, trioctylphosphine, oleylamine, or combinations thereof.

The first aqueous solution may further include an unsaturated fatty acid. The unsaturated fatty acids may be selected from the group consisting of oleic acid, stearic acid, myristic acid, lauric acid, palmitic acid, elaidic acid, The organic acid may be selected from the group consisting of eicosanoic acid, heneicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, It may be at least one of heptacosanoic acid, octacosanoic acid and cis-13-docosenoic acid.

The second aqueous solution may be prepared by mixing a chalcogen element-containing compound with a solvent. The first aqueous solution may be prepared by adding the chalcogen element-containing compound to the solvent and stirring at room temperature. When stirring, a purge gas can be injected. The purge gas may be an inert gas. For example, the purge gas may be argon. The stirring process may be carried out for about 30 minutes to 2 hours, preferably for 1 hour.

The chalcogen element-containing compound may be at least one of sulfur powder, selenium powder, tellurium powder, polonium powder and octanethiol. For example, the chalcogen element-containing compound may be selenium powder.

The solvent may be one or a combination of trioctylphosphine, tributylphosphine, and trioctylamine. For example, the solvent may be trioctylphosphine.

The third aqueous solution may be prepared by mixing a second metal-containing compound with an organic solvent. The third aqueous solution may be prepared by adding the second metal-containing compound to the organic solvent and stirring at 100-200 ° C. When stirring, a purge gas can be injected. The purge gas may be an inert gas. For example, the purge gas may be argon. The stirring process may be carried out for about 30 minutes to 2 hours, preferably for 1 hour.

The second metal may be one of a group 12 element different from the first metal. For example, the first metal may be cadmium and the second metal may be zinc. In this case, the second metal-containing material may be zinc acetic acid (Zn (CH ₃ COO) ₂ 2H ₂ O).

The organic solvent may be hexadecylamine, trioctylamine, octadecene, octadecane, trioctylphosphine, oleylamine, or combinations thereof.

The first aqueous solution may further include an unsaturated fatty acid. The unsaturated fatty acids may be selected from the group consisting of oleic acid, stearic acid, myristic acid, lauric acid, palmitic acid, elaidic acid, The organic acid may be selected from the group consisting of eicosanoic acid, heneicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, It may be at least one of heptacosanoic acid, octacosanoic acid and cis-13-docosenoic acid.

The mixed solution may be prepared by mixing the first aqueous solution, the second aqueous solution and the third aqueous solution prepared by the above-described method (S20). A crystal growth regulator including an amine group may be added to the mixed solution. For example, the crystal growth modifier may be one or a combination of dodecylamine (DDA) and octylamine. Since the amine included in the crystal growth regulator has weak binding force with the surface of the nanoparticles, when the quantum dot is prepared using the mixed solution, the growth rate can be controlled during nucleation and crystal growth have. When the quantum dots of the core shell structure are formed by adding the crystal growth regulator to the mixed solution, the core and the shell are formed at one time by omitting the washing process, . This makes it possible to simplify the manufacturing process and lower the manufacturing cost.

The mixed solution may be supplied to the reactor to form the quantum dots of the core shell structure (S30). When the mixed solution is continuously supplied through the tube 106 in the reactor containing the silicone oil, the nuclei of the quantum dot phosphors are generated when the concentration exceeds the critical point, and the quantum dots gradually grow due to the reaction parameters after the nucleation. According to the present invention, after the first metal contained in the mixed solution and the chalcogen element first react to form a core, the second metal contained in the mixed solution and the chalcogen element react with each other to form a shell .

According to one embodiment, the concentration of the second metal in the mixed solution supplied to the reactor can be gradually increased. In this case, when nuclei for forming quantum dots are generated, the concentration of the second metal is very low, so that the first metal and the chalcogen element can react smoothly. When forming the shell, the concentration of the second metal So that the second metal and the chalcogen element can react well.

According to one embodiment, the mixed solution may be supplied to the reactor at a flow rate of 150-600 μl / min. When the flow rate of the mixed solution is lower than 150 / / min, the amount of the first metal, the second metal and the chalcogen element supplied into the reactor may be too small to produce nucleation and crystal growth. When the flow rate of the mixed solution is more than 600 / / min, the flow rate is too fast and the nucleation and crystal growth are not smooth. Therefore, the peak of the quantum dot in the wavelength band where the peak should occur It may not occur.

According to one embodiment, preparing the quantum dot by supplying the mixed solution to the reactor can be performed at a reaction temperature of 230 to 260 ° C. If the reaction temperature is lower than 230 ° C, the nucleation and crystal growth are not performed well, and the quantum efficiency may be lowered due to deterioration of the characteristics of the quantum dots. When the reaction temperature is higher than 260 ° C, the photoluminescence peak shifts toward the longer wavelength side and the quantum efficiency may drop sharply as shown in FIG.

According to an embodiment, the ratio of the concentration of the first metal to the concentration of the second metal in the mixed solution may be 0.2 or less. If the ratio of the concentration of the second metal is high, the concentration of the second metal in the whole mixed solution is high, so that the reaction between the first metal and the chalcogen element may not be smooth at the initial stage of crystal growth. In this case, the formed quantum dots do not have a core shell structure, and the characteristics such as quantum efficiency and the like may be degraded.

The mixing solution is prepared by mixing the first aqueous solution and the second aqueous solution to prepare a first mixed solution and mixing the second aqueous solution and the third aqueous solution to form a second mixed solution step . ≪ / RTI > In this case, the step of supplying the mixed solution to the reactor may include supplying the first mixed solution of the first aqueous solution and the second aqueous solution to the reactor, and supplying the second mixed solution of the second aqueous solution and the third aqueous solution To the reactor, in order. By sequentially supplying the first mixed solution and the second mixed solution, quantum dots having a core shell structure with improved characteristics can be formed.

In this case, according to an embodiment, the second mixed solution may be supplied to the reactor sequentially while supplying the first mixed solution to the reactor. In other words, the proportion of the second mixed solution supplied into the reactor can be gradually increased. Thus, it can be easily formed in the quantum dots of the core shell structure.

A crystal growth regulator including an amine group may be added to the first mixed solution and the second mixed solution. For example, the crystal growth modifier may be one or a combination of dodecylamine (DDA) and octylamine.

According to an embodiment, the concentration of the second metal in the second mixed solution supplied to the reactor may be gradually increased.

In order to manufacture the quantum dot according to the present invention, a manufacturing apparatus as shown in FIG. 4 can be used. 4 is an example of an apparatus for fabricating quantum dots according to an embodiment of the present invention. For example, the manufacturing apparatus may be a microreactor.

4, the apparatus for manufacturing quantum dots includes a reactor 101, a temperature control mantle 102, a solution injection pump 103, a UV inspection unit 104, and a particle recovery unit 105 can do. The mixed solution is reacted in the tube 106 in the reactor 101 to form quantum dots.

According to one embodiment, the diameter of the tube 106 in the thermostatic mantle 102 may be varied. For example, the diameter of the first portion of the tube 106 adjacent the UV inspection portion 104 may be narrower than the diameter of the second portion of the tube 106 adjacent the solution injection pump 103. Alternatively, for example, the diameter of the first portion of the tube 106 adjacent to the UV inspection portion 104 may be greater than the diameter of the second portion of the tube 106 adjacent the solution injection pump 103 It can be wider. The diameter of the tube 106 may gradually become narrower or wider as it goes from the solution injection pump 103 to the UV inspection unit 104. Accordingly, the flow rate of the mixed solution injected into the tube 106 is controlled, and the time during which the mixed solution stays in the temperature regulation mantle 102 is adjusted, thereby controlling the quantum dot characteristic, Quantum dots having various properties according to the application can be easily manufactured.

Alternatively, according to one embodiment, the reactor 101 may be divided into a plurality of sections separated from each other. For example, when the reactor 101 comprises a first section and a second section that are independently separated from each other, the first temperature control mantle in the first section and the second temperature control mantle in the second section One end of the tube 106 is connected to the solution injection pump 130 and the other end of the tube 106 is connected to the UV inspection unit 104 so that the tube 106 The first temperature control mantle and the second temperature control mantle. That is, a first portion adjacent to the one end of the tube 106 may be disposed within the first temperature control mantle, and a second portion adjacent the other end of the tube 106 may be disposed within the second temperature control mantle. have. In this case, the first temperature control mantle and the second temperature control mantle may have different temperatures. Accordingly, the mixed solution injected into the tube 106 can be thermally treated at different temperatures by the first temperature control mantle and the second temperature control mantle, whereby the quantum dot characteristics to be manufactured are controlled , Quantum dots having various characteristics can be easily manufactured depending on the application.

The reactor 101 may be surrounded by the temperature control mantle 102. The temperature control mantle 102 maintains the reaction temperature in the reactor at a constant temperature since it must be maintained at a constant temperature when the quantum dots are manufactured.

The quantum dot manufacturing apparatus may include a solution injection pump 103 for supplying the mixed solution to the reactor 101. The solution injection pump 103 can supply the mixed solution into the reactor at a constant flow rate. The solution injection pump may be a syringe pump or a constant speed pump.

The quantum dot manufacturing apparatus may include a UV inspection unit 104. The UV inspecting unit 104 irradiates UV light before the quantum dot particles are collected to check the characteristics of the quantum dots formed in the reactor 101. The quantum dot particles inspected by the UV inspection unit 104 may be recovered to the recovery unit 105. The recovered quantum dot particles may be washed by the recovery unit 105.

<Experimental Example According to Flow Rate of Mixed Solution>

In Experimental Examples 1 to 6, mixed solutions were prepared by mixing 50 ml of cadmium aqueous solution, 50 ml of selenium aqueous solution, 10 ml of zinc aqueous solution and 10 g of dodecylamine. Experimental Examples 1 to 3 proceeded at a reaction temperature of 270 ° C, and Experimental Examples 4 to 6 proceeded at a reaction temperature of 290 ° C. The mixed solution was supplied to the reactor at a flow rate of 150 占 퐉 / min in Experimental Examples 1 and 4, 300 占 퐉 / min in Experiment Examples 2 and 5, and 600 占 퐉 / min in Experimental Examples 3 and 6, The UV peak (UV-P), the photoluminescence peak (PL-P) and the quantum yield (QY-6G, QY-B) were measured for the quantum dot particles. QY-6G in the quantum yield shows the luminescence and fluorescence intensities measured by relative comparison using Rhodamine 6G dye. QY-B shows luminescence intensity and fluorescence intensity measured by relative comparison using rhodamine B Rhodamine B) dye.

As shown in FIG. 5 and Table 1, as the flow rate of the mixed solution is increased, the wavelengths of the UV peak (UV-P) and the photoluminescence peak (PL-P) are shortened and the quantum yield is increased. However, as described above, when the flow rate exceeds 600 탆 / min, the nucleation of the flow rate is not properly performed and the UV peak does not appear and the characteristics of the quantum dot may be deteriorated. Table 1 shows the characteristics of the quantum dots according to the flow rate.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Experimental Example 6 UV-P (nm) 595.4 577.1 554.6 597.2 585.6 569.9 PL-P (nm) 604 588 567 606 594 577 QY-6G (%) 17.3 23.5 33.2 22.5 24.7 26.5 QY-B (%) 18.5 25.2 35.6 24.1 30.6 32.8

<Experimental Example According to Reaction Temperature>

In Experimental Examples 7 to 11, mixed solutions were prepared by mixing 50 ml of cadmium aqueous solution, 50 ml of selenium aqueous solution, 10 ml of zinc aqueous solution and 10 g of dodecylamine. Experimental Example 7 was conducted at a reaction temperature of 250 ° C, Experimental Example 8 was 270 ° C and Experimental Example 9 was conducted at a reaction temperature of 290 ° C. In Experimental Examples 7 to 9, the mixed solution was supplied to the reactor at a flow rate of 150 μm / min (UV-P), photoluminescence peak (PL-P) and quantum yield (QY-6G, QY-B) were measured for the quantum dot particles.

Also, the reaction solution was observed at 210 캜 for Experimental Example 10 and at a reaction rate of 150 탆 / min at a reaction temperature of 230 캜 for Experimental Example 11, and the reaction solution for the produced quantum dots was confirmed.

As shown in Fig. 6 and Table 2, the wavelengths of the upper UV peak (UV-P) and the photoluminescence peak (PL-P) at which the reaction temperature is higher are shortened and the quantum yield is increased. However, when the reaction temperature is lower than 230 ° C as shown in the above description and in FIG. 7, the reaction temperature is too low to form the core shell structure of the produced quantum dots and the characteristics may be deteriorated. Table 2 shows the characteristics of the quantum dots according to the reaction temperature.

Experimental Example 7 Experimental Example 8 Experimental Example 9 UV-P (nm) 595.4 577.1 554.6 PL-P (nm) 604 588 567 QY-6G (%) 17.3 23.5 33.2 QY-B (%) 18.5 25.2 35.6

<According to composition ratio of zinc Experimental Example >

In Experimental Examples 12, 13, 16 and 17, mixed solutions were prepared by mixing 50 ml of aqueous cadmium solution, 50 ml of selenium aqueous solution, 5 ml of aqueous zinc solution and 3.83 g of dodecylamine. In Experimental Example 14, Experimental Example 15, Experimental Example 18 and Experimental Example 19, a mixed solution was prepared by mixing 50 ml of aqueous cadmium solution, 50 ml of selenium aqueous solution, 1 ml of zinc aqueous solution and 3.83 g of dodecylamine.

In Experimental Examples 12 to 19, the reaction temperature was 270 ° C., and in Experimental Examples 12, 14, 16 and 18, the mixed solution was supplied at a flow rate of 150 μm / min. 19 was supplied with the mixed solution at a flow rate of 300 mu m / min. In Experimental Examples 12 to 15, a mixed solution was supplied by a syringe pump. In Experimental Examples 16 to 19, quantum dots were prepared by supplying a mixed solution with a constant speed pump.

The UV peak (UV-P), the photoluminescence peak (PL-P) and the quantum yield (QY-6G, QY-B) were measured for each of the produced quantum dot particles.

8, 9 and Table 3, it can be seen that the quantum yield increases when the composition ratio of zinc is low. That is, when the composition ratio of zinc is high, zinc may react with selenium at the beginning of crystal growth of the quantum dots and ZnSe may be formed in the core region, so that the characteristics of the quantum dots may be deteriorated. Also, it was confirmed that the smaller the flow rate, the higher the quantum yield even in the same concentration.

In addition, when the mixed solution was supplied to the reactor using a constant speed pump rather than the syringe pump, it was confirmed that the quantum yield was high and the peak of the UV peak and the photoluminescence peak (PL-P) shifted to the short side. Table 3 shows the characteristics of the quantum dots according to the composition ratio of zinc.

Experimental Example 12 Experimental Example 13 Experimental Example 14 Experimental Example 15 Experimental Example 16 Experimental Example 17 Experimental Example 18 Experimental Example 19 UV-P (nm) 552.0 536.5 541.0 523.5 536.7 505.3 520.7 497.6 PL-P (nm) 566 549 555 538 549 519 536 512 QY-6G (%) 17.1 19.7 22.4 20.9 35.3 33.6 33.5 34.3 QY-B (%) 14.6 16.8 19.1 17.8 30 28.6 28.5 29.2

<According to Crystal Growth Regulator Experimental Example >

In Experimental Examples 20 and 21, a mixed solution was prepared by mixing 50 ml of aqueous cadmium solution, 50 ml of selenium aqueous solution, 5 ml of zinc aqueous solution and 4 g of octylamine. Experimental Example 22 and Experimental Example 23 contained 50 ml of aqueous cadmium solution, , 1 ml of zinc solution and 4 g of octylamine were mixed to prepare a mixed solution.

In Experimental Examples 20 to 23, the reaction temperature was 270 DEG C, and in Experimental Examples 20 and 22, the mixed solution was supplied at a flow rate of 150 mu m / min. In Experimental Examples 21 and 23, (UV-P), photoluminescence peak (PL-P), and quantum yield (QY-6G, QY-B) were measured for each quantum dot particle after the mixed solution was supplied at a flow rate Respectively.

9, 10 and Table 4, the peak of the UV peak and the photoluminescence peak (PL-P) was longer when octylamine was added than when dodecylamine was added as the growth regulator Respectively. However, both dodecylamine and octylamine exhibited similar efficiencies in terms of quantum yield. <Table 4> shows the characteristics of quantum dots according to crystal growth regulators

Experimental Example 16 Experimental Example 17 Experimental Example 18 Experimental Example 19 Experimental Example 20 Experimental Example 21 Experimental Example 22 Experimental Example 22 UV-P (nm) 536.7 505.3 520.7 497.6 574.4 552.8 559.1 529.8 PL-P (nm) 549 519 536 512 581 560 539 567 QY-6G (%) 35.3 33.6 33.5 34.3 22.4 38.5 33.6 31.6 QY-B (%) 30 28.6 28.5 29.2 19.1 24.2 28.6 26.9

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

101: Reactor
102: Temperature control mantle
103: solution injection pump
104: UV inspection section
105: Particle recovery unit
106: tube

Claims (6)

Preparing a first aqueous solution comprising a first metal;
Preparing a second aqueous solution comprising a chalcogen element;
Preparing a third aqueous solution comprising a second metal;
Mixing the first aqueous solution, the second aqueous solution and the third aqueous solution; And
And supplying the mixed solution to the reactor,
Wherein the first metal and the second metal are different Group 12 elements,
Wherein the mixed solution comprises a crystal growth regulator comprising an amine group,
Wherein the step of supplying the mixed solution to the reactor comprises gradually increasing the concentration of the second metal,
The reactor is placed in a thermostatic mantle,
A tube through which the mixed solution flows is disposed in the reactor,
Wherein the diameter of the tube gradually narrows or gradually increases to control the flow rate of the mixed solution and the time during which the mixed solution stays in the temperature control mantle.
The method according to claim 1,
Wherein the temperature regulating mantle comprises a first temperature regulating mantle and a second temperature regulating mantle having different temperatures,
The tube is disposed within the first thermostatting mantle and the second thermostatting mantle,
Wherein the mixed solution flowing in the tube is heat-treated by the first temperature control mantle and then heat-treated by the second temperature control mantle at a temperature different from the heat treatment temperature by the first temperature control mantle. Way.
The method according to claim 1,
Wherein the step of supplying the mixed solution to the reactor is performed at a reaction temperature of 230 to 260 ° C.
The method according to claim 1,
Wherein the mixed solution is supplied at a flow rate of 150 to 600 L / min.
The method according to claim 1,
Wherein the concentration ratio of the second metal to the concentration of the first metal in the mixed solution is 0.2 or less.
The method according to claim 1,
Mixing the first aqueous solution, the second aqueous solution and the third aqueous solution comprises:
Mixing the first aqueous solution and the second aqueous solution; And
Mixing the second aqueous solution and the third aqueous solution,
Wherein the step of supplying the mixed solution to the reactor comprises:
Supplying a mixed solution of the first aqueous solution and the second aqueous solution to a reactor, and supplying a mixed solution of the second aqueous solution and the third aqueous solution to the reactor.

Images