KR20200044485A - Method for manufacturing high-purity nano zinc oxide powder and surface-coated high-purity nano zinc oxide powder - Google Patents

Abstract

The present invention relates to a method for manufacturing high-purity nano zinc oxide powder and surface-coated high-purity nano zinc oxide powder. According to one embodiment of the present invention, by controlling a plurality of process conditions, not just temperature, it is possible to precisely and uniformly adjust a particle size, particle shape and purity of the zinc oxide powder. According to another embodiment of the present invention, by forming a uniform coating layer on the zinc oxide powder, it is possible to provide excellent dispersibility and viscosity stability. Due to the effects, it is possible to provide zinc oxide suitable for the purpose of each of the electric, optical, and cosmetic fields.

Description

Manufacturing method of high purity nano zinc oxide powder and surface coated high purity nano zinc oxide powder {METHOD FOR MANUFACTURING HIGH-PURITY NANO ZINC OXIDE POWDER AND SURFACE-COATED HIGH-PURITY NANO ZINC OXIDE POWDER}

It relates to a method for producing a high purity nano zinc oxide powder and a surface-coated high purity nano zinc oxide powder, and more specifically, the conditions of the mixed solution preparation step, the conditions of removing impurities, the conditions of the sodium carbonate aqueous solution reaction step, the basic zinc carbonate (ZnCO) ₃ · Zn (OH) ₂ ) High purity nano zinc oxide powder and surface that can precisely and uniformly control the size and shape of the zinc oxide powder particles by controlling a plurality of process conditions such as the conditions of the separation step and the conditions of the calcination step. It relates to a method for producing a coated high purity nano zinc oxide powder.

In general, zinc oxide has an optical property that transmits 85 to 95% of visible light. Due to these optical properties, it is a material that has attracted much attention both electrically and optically, and has been applied to various fields such as a photocatalyst and a display fluorescent layer, and in particular, studies are being actively conducted to find out the possibility of use as a fuel-sensitized solar cell. have. While zinc oxide transmits visible light as described above, it exhibits an excellent blocking effect against ultraviolet rays, which are known to be harmful to the human body, and has been applied to sunscreens used in cosmetics due to such blocking effect. Ultraviolet rays are subdivided into three areas: UV-A (320-400nm), UV-B (290-320nm), and UV-C (200-290nm), of which zinc oxide penetrates the dermal layer of the skin and promotes skin aging It shows excellent blocking effect against UV-A.

However, despite the advantages of zinc oxide, there is a problem that it is difficult to produce natural makeup due to the irregular feeling of the zinc oxide powder particles, and due to the cloudiness. In Korean Patent Publication No. 10-2003-0038046, the size of the zinc oxide powder particles is controlled by controlling the calcination temperature, but the particle size control depends only on a single temperature control process, resulting in poor uniformity and the shape of the zinc oxide powder particles. There is still the problem of irregularity.

Accordingly, there is a need to develop a particle shape control technology and an improved manufacturing process to which the zinc oxide powder particles have an appropriate particle size and have a uniform shape at the same time.

Republic of Korea Patent Publication No. 10-2003-0038046

Transactions of the Institute of Mining and Metallurgy (Monhemius, A. l, 1977, Vol. 86, pp. 202-206)

The present invention has been devised to solve the above problems, and the object of the present invention is to precisely and uniformly control the size and shape of the zinc oxide powder particles, high purity nano zinc oxide powder and surface coated high purity nano zinc oxide. It is to provide a method for producing a powder.

In order to achieve the above object of the present invention, the present invention (a) dissolving zinc by-products in an acidic solution to prepare a mixed solution, (b) removing impurities from the mixed solution prepared in the step (a) step, (c) reacting with an aqueous solution of sodium carbonate was added to a mixed solution of (b) by the step impurities are removed, (d) ₃ · Zn of basic zinc carbonate (ZnCO generated by the reaction of the step (c) ( OH) ₂ ) by filtering and separating, and (e) adding and calcining the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) into a rotary incinerator. Provided is a method of manufacturing a coated high purity nano zinc oxide powder.

According to an embodiment of the present invention, by controlling a plurality of process conditions, not only temperature control, it is possible to precisely and uniformly control the particle size, particle shape and purity of the zinc oxide powder, and to another embodiment of the present invention According to this, by forming a uniform coating layer on the zinc oxide powder, it is possible to provide excellent dispersibility and viscosity stability. Due to the above effects, it is possible to provide zinc oxide suitable for the purpose of each of the electric, optical, and cosmetic fields.

1 is a flow chart showing a method of manufacturing a zinc oxide powder according to an embodiment of the present invention.
Figure 2 is a flow chart showing the steps of removing impurities from the mixed solution according to an embodiment of the present invention.
Figure 3 is a flow chart showing a method of manufacturing a surface-coated zinc oxide powder according to another embodiment of the present invention.
4 is a view showing the results of a scanning electron microscope analysis of zinc carbonate according to an embodiment of the present invention.
5 is a view showing a scanning electron microscope analysis result and a transmission electron microscope analysis result of the zinc oxide powder according to an embodiment of the present invention.
6 is a view showing the results of X-ray diffraction analysis of the surface coated zinc oxide powder according to another embodiment of the present invention.
7 is a view showing a scanning electron microscope analysis result and a transmission electron microscope analysis result of the surface coated zinc oxide powder according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples and drawings.

The present invention comprises (a) dissolving zinc by-product in an acidic solution to prepare a mixed solution, (b) removing impurities from the mixed solution prepared in step (a), (c) step (b) Reacting by adding an aqueous sodium carbonate solution to the mixed solution from which impurities have been removed, (d) filtering and separating the basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) produced by the reaction of step (c), And (e) adding and calcining the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) into a rotary incinerator to provide a method for producing high purity nano zinc oxide powder.

The zinc by-product, which is a raw material used in step (a) of the manufacturing method of the present invention, can contain any form of zinc by-product as long as it contains a component that can be dissolved in an acidic solution, and is derived from the dry process (French process) manufacturing process. It can be a by-product of zinc. Zinc by-products derived from the dry process (French process) manufacturing process generally contain 65 to 68% by weight of zinc (Zn), and impurities are 2.0 to 3.0% by weight of aluminum (Al), 3.0 to 4.0% by weight % Iron (Fe), 2.0 to 3.0% by weight of lead (Pb), 0.5 to 1.0% by weight of copper (Cu) metal impurities, 20 to 21% by weight of acid insolubles (impurities not soluble in acidic solution) It contains. In the embodiment of the present invention, the zinc by-product derived from the dry process (French process) manufacturing process is described, but is not limited thereto. In addition to zinc, the zinc by-product contains metal impurities such as aluminum, iron, lead, and copper, and impurities (insoluble in acids) that are not dissolved in an acidic solution, and the present invention efficiently removes the impurities from zinc by-products, resulting in high purity nano It is an object to produce zinc oxide powder.

Another raw material used in step (a) of the production method of the present invention can be used as long as a zinc salt solution can be obtained, and it is preferable to use an acidic solution having a hydrogen ion concentration index (pH) of 3 or less. Do. For example, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, and bromic acid, acetic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, fumaric acid, maleic acid, malonic acid, phthalic acid, succinic acid, Organic acids such as lactic acid, citric acid, citric acid, gluconic acid, tartaric acid, salicylic acid, malic acid, oxalic acid, benzoic acid, embonic acid, aspartic acid, glutamic acid can be used. In terms of production cost and side reaction, inorganic acid is preferred, and sulfuric acid or hydrochloric acid is more preferred in terms of calcination under low temperature conditions and reaction with an aqueous sodium carbonate solution.

In the manufacturing method of the present invention, step (b) is (b1) a primary filtration step of removing the slag contained in the mixed solution prepared in step (a), (b2) the slag is removed by the step (b1) A second filtration step of removing the metal ion hydroxide produced by adding an oxidizing agent and a neutralizing agent to the mixed solution, and (b3) a trace amount of residual metal by adding a reducing agent to the mixed solution from which the metal ion hydroxide was removed by the step (b2) And a third filtration step to remove particles.

The slag removed in step (b1) refers to impurities that are not dissolved in the acidic solution and a precipitate formed by reacting with the acidic solution. The impurities that are not soluble in the acidic solution include corundum (Al ₂ O ₃ ), crystalline particles of the alumina system, mullite (Mullite, 3Al ₂ O ₃ · 2SiO ₂ ), and anthite (crystalline particles of the ceramic system). And poorly soluble heavy minerals such as CaAl ₂ Si ₂ O ₈ ), and examples of precipitates generated by reaction with an acidic solution include barium salts or mercury salts.

The oxidizing agent added in step (b2) is added to form iron trivalent ions by oxidizing iron divalent ions contained in the mixed solution from which slag is removed by step (b1). The mixed solution from which the slag was removed contains not only iron divalent ions but also iron trivalent ions, and iron ions are each hydroxide of iron (II) hydroxide (Fe (OH) ₂ ) and iron hydroxide (III) (Fe (OH). ₃ , Bernalite), it is not easy to recover. For example, according to Non-Patent Document 1, at 25 ° C., iron divalent ions precipitate with iron hydroxide (II) as a hydroxide at pH 6.0 or higher, wherein the pH region of the 6.0 is Zn (OH) hydroxide of zinc ions. There is a problem of overlapping with the pH region that precipitates as ₂ . Therefore, by oxidizing the iron trivalent ion state, the iron trivalent ion is precipitated with iron (III) hydroxide as a hydroxide at a pH range of 2 to 3, thereby reducing zinc loss. Therefore, prior to forming a hydroxide-type precipitate, first, when an iron divalent ion is oxidized to an iron trivalent ion using an oxidizing agent, only iron hydroxide (III) generated as a hydroxide of the iron trivalent ion needs to be removed, so the process In terms of economical efficiency, it is possible to increase the purity of the resulting zinc oxide powder.

The oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, permanganic acid, permanganate, sulfate, persulfate, perchloric acid, perchlorate, hypochlorous acid, hypochlorite, periodic acid, periodate, and mixtures thereof. It can be used, and it is preferable to use hydrogen peroxide or hypochlorous acid.

The oxidizing agent may be added in 0.5 to 1 part by weight compared to 100 parts by weight of the mixed solution from which slag is removed by the step (b1). When the content of the oxidizing agent is less than 0.5 parts by weight, the oxidation reaction of the metal ion may be delayed and lowered, and when the content of the oxidizing agent exceeds 1 part by weight, there is a risk of economic loss due to an increase in manufacturing cost.

The iron trivalent ion formed by adding the oxidizing agent reacts with a neutralizing agent on the mixed solution having a hydrogen ion concentration index (pH) of 3 to 4 to generate a precipitate in the form of a metal ion hydroxide. It is preferable that the hydrogen ion concentration index is more than 3 and less than 4.

Therefore, the term 'metal ion hydroxide produced by adding an oxidizing agent and a neutralizing agent' used in the present invention includes (1) a step of forming an iron trivalent ion by adding an oxidizing agent to a mixed solution from which slag is removed, and (2) Refers to the result of the step of producing a metal ion hydroxide from the reaction of an iron trivalent ion and a neutralizing agent.

The neutralizing agent may be one or more selected from the group consisting of a basic substance such as sodium hydroxide, ammonia water, limestone, calcium silicate, calcium carbonate, and sodium hydroxide or ammonia water is preferably used.

The precipitate in the form of metal ion hydroxide can be separated and / or removed through filtration.

The reducing agent added in the step (b2) is added to form metal particles by reducing the remaining metal ions contained in the mixed solution from which the metal ion hydroxide was removed by the step (b2). The remaining metal ions include aluminum ions, iron ions, and copper ions.

The reducing agent is selected from the group consisting of zinc powder, potassium permanganate, hydrazine, hydroquinone, sodium borohydride, hexamethylenetetramine, alkylamine, alkylenediamine, alkylenetriamine, alkylenetetramine, and mixtures thereof. It is possible to use one or more kinds, and it is preferable to use zinc powder or potassium permanganate.

The reducing agent may be added in 0.5 to 1 part by weight compared to 100 parts by weight of the mixed solution from which the metal ion hydroxide is removed by the step (b2). When the content of the reducing agent is less than 0.5 part by weight, there is a fear that the reduction reaction of the metal ion is lowered, and when the content of the reducing agent exceeds 1 part by weight, there is a fear of economic loss due to an increase in manufacturing cost.

The remaining metal ions contained in the mixed solution from which the metal ion hydroxide has been removed react with the following formula to produce a precipitate in the form of metal particles.

The precipitate in the form of metal particles may be separated and / or removed through filtration.

In the manufacturing method of the present invention, the step of removing impurities from the mixed solution prepared in step (a) includes steps (b1) to (b3) to remove impurities of slag, metal ion hydroxide, and metal particles, and finally It is possible to increase the purity of the zinc oxide powder produced.

The sodium carbonate aqueous solution used in step (c) of the manufacturing method of the present invention is reacted with zinc salt contained in the mixed solution from which impurities are removed by step (b) to react basic zinc carbonate (ZnCO ₃ · Zn) (OH) ₂ ) A solid product is formed.

When using sodium hydroxide aqueous solution, which was used to prepare zinc oxide powder in the prior art, it precipitates as zinc hydroxide having an irregular particle structure, whereas when using sodium carbonate aqueous solution, it precipitates as zinc carbonate, and regular spherical zinc oxide through a heat treatment process to be described later. Powders can be prepared. By producing a regular spherical zinc oxide powder, it is possible to increase the feeling of use of a sunscreen used in cosmetic applications.

It is preferable that the pH condition of the step (c) is 7 to 8. If the pH is outside the above range, the yield of the basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) solid product is lowered, and the purity of the resulting zinc oxide powder may be lowered.

The aqueous sodium carbonate solution in step (c) is preferably added at a volume flow rate of 30 to 70 L / min. When the volume flow rate of the aqueous sodium carbonate solution is less than 30 L / min, there is a fear that the time for the reaction of generating a basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) solid product is delayed and there is a fear of productivity decrease. When the volumetric flow rate of the aqueous sodium carbonate solution exceeds 70 L / min, the uniformity of the basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) solid product decreases, resulting in poor particle uniformity of the resulting zinc oxide powder. There is a fear of affecting chromaticity.

The reaction molar ratio of zinc salt contained in the mixed solution from which impurities are removed by step (b) and the sodium carbonate of step (c) may be 1: 0.8 to 1.3, and more preferably 1: 1.2 to 1.3. Do. When the reaction molar ratio is less than 1: 0.8, platelet zinc sulfate is mixed due to precipitation of unreacted zinc salt, which is difficult to remove even through filtration and washing, so that the purity and whiteness of the zinc oxide powder finally produced decreases. It might be. When the reaction molar ratio exceeds 1: 1.3, due to precipitation of unreacted carbonate and formation of a fine-sized solid product, there is a fear that the progress of filtration is delayed or the purity and whiteness of the zinc oxide powder finally produced are lowered.

In step (d) of the production method of the present invention, the basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) produced by the reaction of step (c) is separated through filtration, and formed by the reaction of step (c). Sodium sulfate (Na ₂ SO ₄ ) and unreacted carbonate are washed off with water.

The production method of the present invention may further include drying the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) in a heat dryer.

In the manufacturing method of the present invention, step (e) is a step of preparing a high purity nano zinc oxide powder by calcining the basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) separated by filtration in step (d). The calcination of step (e) is performed by introducing the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) into a rotary incinerator. When the calcination process is performed by a rotary incinerator, there is an advantage in that the internal conditions can be adjusted to suit the purpose, compared to the case where the calcination process is performed by a batch incinerator used to produce a conventional zinc oxide powder. That is, by controlling the internal conditions such as the supply flow rate, rotation speed, and temperature of the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ), which is the calcined raw material, the purity and whiteness of the finally produced zinc oxide powder are controlled. can do.

Through the calcination performed by the rotary incinerator in which the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) is added, a high purity nano zinc oxide (ZnO) powder is produced through the following formula.

In the step (e), it is possible to produce high purity nano zinc oxide nano powder in a temperature range of 500 to 600 ° C by the rotary incinerator. The temperature is more preferably 550 ° C. At this time, the particle size of the zinc oxide powder finally produced according to the calcination temperature may be variously prepared from 5 to 500 nm. When the calcination temperature is less than 500 ° C, the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) may remain, and the particles of zinc oxide powder finally produced when the calcination temperature exceeds 600 ° C There is a fear that the size will increase. Specifically, when the calcination temperature is less than the lower limit, zinc oxide powder having a particle size of less than 5 nm is manufactured to realize nano-class products, but the purity is lowered, and due to the high specific surface area, application to the product is limited. There is, the uniform surface coating to be described later is difficult due to the aggregation phenomenon of the particles. When the calcination temperature exceeds the upper limit, it is difficult to implement nano-type zinc oxide powder due to increased grain growth, it is difficult to realize desired properties, and zinc oxide powder having a particle size exceeding 500 nm is prepared, so that light is visible in the visible light region. The transmittance decreases and the ability to absorb ultraviolet rays decreases.

5 is a view showing a scanning electron microscope analysis result and a transmission electron microscope result of zinc oxide powder according to the calcination temperature, and FIGS. 5A, 5B, 5C, and 5D are zinc oxide powder calcined at 550, 400, 700, and 900 ° C, respectively. It is a view showing.

In the step (e), oxygen may be introduced into the rotary incinerator at a volume flow rate of 10 to 30 L / min, and more preferably 20 L / min. By controlling the volume flow rate, the amount of carbon dioxide (CO ₂ ) produced in step (e) is controlled, so that the whiteness of the finally produced zinc oxide powder can be controlled. When the volume flow rate of the supplied oxygen exceeds the above upper limit, the temperature variation for each section of the rotary incinerator is widely distributed, which may result in a decrease in uniformity and a deviation in purity during heat treatment. In addition, when the volume flow rate of oxygen supplied is less than the above lower limit, the internal oxidizing atmosphere decreases due to an increase in CO ₂ gas generated during thermal decomposition of zinc carbonate, which leads to a decrease in the whiteness of the finally produced product.

In the step (e), the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) may be introduced into the rotary incinerator at a mass flow rate of 50 to 150 kg / hr, more preferably 100 kg / hr. Do. When the mass flow rate is less than 50 kg / hr, there is a fear of economic loss due to productivity decrease, and whiteness of the finally produced product is reduced. When the mass flow rate exceeds 150 kg / hr, there is a concern that the variation in purity and specific surface area of the zinc oxide powder finally produced is widely distributed, making it difficult to implement a uniform particle shape.

In the step (e), the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) in the rotary incinerator may be calcined while rotating at a rotational speed of 1 to 9 rpm, more preferably 5 rpm. If the rotational speed is less than the lower limit, there is a fear that the mixing property between products due to rotation is insufficient due to insufficient rotational force, and if the rotational speed exceeds the upper limit, there is a risk of overloading the dust collection facility due to excessive dust generation. .

The present invention also (a) preparing a mixed solution by mixing the zinc oxide powder and the surface treatment agent prepared by the above method with an organic solvent, (b) wet grinding the mixed solution prepared in the step (a) Providing a method for producing a surface-coated high purity nano zinc oxide powder comprising forming water, (c) vacuum drying the pulverized material to separate solid materials, and (d) dry pulverizing the solid materials. do.

The surface treatment agent of step (a) is preferably a fluorine-based surface treatment agent or a silicone-based surface treatment agent, and more preferably a silicone-based surface treatment agent. The silicone-based surface treatment agent of the present invention is an alkyl acrylate copolymer methylpolysiloxane ester, stearic acid, n-octyl triethoxy silane, methylhydrogenpolysiloxane ), Methylpolysiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, hydroxyterminated dimethylpolysiloxane, and mixtures thereof.

According to the manufacturing method of the present invention, the thickness of the surface coating can be controlled by adjusting the addition amount of the surface treatment agent on the basis of the addition amount of the zinc oxide powder. The zinc oxide powder of step (a) and the surface treatment agent may be added in a weight ratio of 100: 2 to 5. When mixed in the above range, it is possible to obtain a surface coating of the most appropriate thickness, which shows very good light stability.

The organic solvent of the step (a) is not particularly limited as long as it is a compound capable of sufficiently emulsifying the zinc oxide powder, and may be, for example, a ketone-based, alkylene glycol ether-based, alcohol-based and aromatic-based compound. Alcohol- or aromatic-based compounds are preferred from the viewpoint of stability and viscosity control of the emulsified solution.

Ketone-based compounds include acetone, methyl ethyl ketone, and cyclohexanone; Alkylene glycol ether-based compounds include methyl cellosolve (ethylene glycol monomethyl ether), butyl cellosolve (ethylene glycol monobutyl ether), methyl cellosolve salt, ethyl cellosolve salt, butyl cellosolve salt, Ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol Monobutyl ether, propylene glycol monomethyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol propyl ether acetate, diethylene glycol isopropyl ether acetate , Diethylene glycol butyl ether acetate, diethylene glycol t-butyl ether acetate, triethylene glycol methyl ether acetate, triethylene glycol ethyl ether acetate, triethylene glycol propyl ether acetate, triethylene glycol isopropyl ether acetate, triethylene glycol butyl Ether acetate, triethylene glycol t-butyl ether acetate, and the like; Alcohol-based compounds include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, 3-methyl-3-methoxybutanol, and the like; Aromatic compounds include benzene, toluene, xylene, N-methyl-2-pyrrolidone, ethyl N-hydroxymethylpyrrolidone-2 acetate, and the like. Additional other solvents include 1,2-propanediol diacetate, 3-methyl-3-methoxybutyl acetate, ethyl acetate, tetrahydrofuran, and the like. The organic solvents may be used alone or as a mixture of each other.

In the manufacturing method of the present invention, wet grinding in the step (b) is a step of pulverizing the mixed solution prepared in the step (a) to form a pulverized product, an air-jet mill, a roller mill ( It can be performed by various instruments or equipment such as Roller Mill, Ball Mill, Attrition Mill, Vibration Mill, Planetary Mill, or Bead Mill. , In the present invention, wet grinding was performed by a bead mill.

When the step (b) is performed by wet grinding, separation between the particles of the agglomerated zinc oxide powder is easy even under a low shearing force compared to the case of dry grinding, whereby a uniform surface on the particles in the wet state There is an advantage that the modification is easy and the coating layer is uniformly formed. Therefore, the dispersibility of the finally produced surface-coated zinc oxide powder is improved, so that the content of solid content can be increased and excellent viscosity stability can be provided.

Step (b) may be performed at 25 to 50 ° C for 2 to 5 hours. When wet grinding is performed in the above range, it is possible to obtain a nano-scale zinc oxide slurry state that is easy to separate and disperse particles of agglomerated zinc oxide powder. When wet grinding is performed at less than 25 ° C, the hydrolysis of the surface treatment agent may be delayed, and when the temperature exceeds 50 ° C, the organic solvent may volatilize.

In the manufacturing method of the present invention, step (c) is a step of vacuum drying the pulverized product prepared in step (b) to separate solid materials, and the pulverized product is dried using a vacuum oven (Vacuum Oven). Step (c) is preferably performed under a pressure lower than atmospheric pressure, and may be performed for 5 to 7 hours at 60 to 80 ° C. When vacuum drying is performed in the above range, a coating layer of zinc oxide powder finally produced may be uniformly formed.

In the manufacturing method of the present invention, the dry grinding in the step (d) is a step of pulverizing the solids separated in the step (c) without a medium such as a solvent to finally form a high purity nano zinc oxide powder coated on the surface, air- Air-jet mill, roller mill, ball mill, attrition mill, vibratory mill, planetary mill, or pin mill It can be performed by a variety of instruments or equipment, and among these, it is preferably performed by an air-jet mill that is crushed by high pressure and high speed air to minimize damage to the final product.

The step (d) may be performed at 25 to 50 ° C for 3 to 5 hours. When dry grinding is performed in the above range, zinc oxide powder having a uniform surface treatment layer can be finally obtained, and thereby physical properties of the surface coated zinc oxide powder can be uniformly formed.

Figure 6 is a view showing the results of X-ray diffraction analysis of the surface-coated zinc oxide powder according to an embodiment of the present invention, the surface-coated zinc oxide powder prepared by the method of the present invention is dense hexagonal made of oxygen It can be confirmed that half of the tetrahedral sites of the Hexagonal Close Packed Lattice (HCP) have a wurtzite structure made of zinc metal.

7 is a view showing a scanning electron microscope analysis result and a transmission electron microscope analysis result of the surface coated zinc oxide powder according to an embodiment of the present invention, according to FIG. 7, the surface coating prepared by the manufacturing method of the present invention It can be confirmed that the coated thickness of the zinc oxide powder was 2 to 5 nm. When the coating layer of the zinc oxide powder produced by the manufacturing method of the present invention is formed in the above thickness range, it can exhibit very good light stability.

{Example}

Hereinafter, the present invention will be described in detail by examples. However, the following examples are only to illustrate the present invention, the content of the present invention is not limited to the following examples.

<Reference Example> Results of composition analysis of zinc by-products

An analysis of the composition of the components of zinc by-products derived from the process of manufacturing the dry method (French method) was conducted. Analysis of component analysis of zinc by-products was performed using an automatic element analyzer (ICP-AES, manufactured by PerkinElmer). The composition of zinc by-products is shown in Tables 1 and 2 (unit: wt%).

division Ingredient composition Zn Al Fe Pb Cu Insoluble matter Total Zinc byproducts 68.0 3.0 4.0 3.0 1.0 21.0 100

division Ingredient composition Mg Al Si Ca Fe Total Insoluble matter 0.1 9.9 2.7 0.1 8.2 21.0

According to Table 1, the zinc by-product derived from the dry process (French process) manufacturing process contains 68% by weight of zinc (Zn), and impurities include 3.0% by weight of aluminum (Al), 4.0% by weight of iron ( Fe), 3.0% by weight of lead (Pb), 1.0% by weight of metal impurities of copper (Cu), it was confirmed to contain 21% by weight of acid insoluble content (impurity insoluble in acidic solution).

In addition, according to Table 2, the acid insoluble matter removed as slag is 0.1% by weight of magnesium (Mg), 9.9% by weight of aluminum (Al), 2.7% by weight of silicon (Si), 0.1% by weight of calcium (Ca) , 8.2 It was confirmed to contain iron (Fe) by weight.

<Production Example 1> Preparation of basic zinc carbonate of Examples 1 to 3 and Comparative Examples 1 to 5

100 g of zinc by-product of the reference example was dissolved in 95% sulfuric acid solution (pH 3) over 120 minutes to prepare 100 ml of zinc sulfate (ZnSO ₄ ) solution. The slag contained in the solution was removed by filtration through filter paper.

In order to form iron trivalent ions in the solution from which the slag was removed, 1 g of an aqueous 35% hydrogen peroxide solution was added as an oxidizing agent. Thereafter, 3 g of a 25% aqueous sodium hydroxide solution was added as a neutralizing agent to maintain the pH at about 3.5, and the temperature was maintained at 25 to 30 ° C. When 120 minutes elapsed after the addition of the oxidizing agent and neutralizing agent, the resulting iron (III) hydroxide precipitate was removed by filtration through filter paper.

1 g of zinc powder was added as a reducing agent over 60 minutes to reduce aluminum ions, iron ions, and copper ions remaining in the solution from which the iron hydroxide (III) precipitate was removed to metal particles. At this time, the pH was maintained at about 5, and the temperature was maintained at 25 to 30 ° C. When about 120 minutes elapsed after the addition of the reducing agent, the reduced metal particles, which are impurities, were filtered off through filter paper.

Then, a sodium carbonate aqueous solution was added to the solution from which the impurities were removed to generate basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) as a reaction product. The reaction temperature was maintained at 25-30 ° C, and the reaction was allowed to proceed for 120 minutes. At this time, the supply volume flow rate of the aqueous sodium carbonate solution added, the reaction molar ratio of the zinc salt and sodium carbonate, and the reaction conditions of the pH are shown in Table 3.

The sodium sulfate (Na ₂ SO ₄ ) formed by the reaction was removed by washing with unreacted carbonate, and the basic zinc carbonate formed during the reaction was separated through a filter paper (90 g, yield: 98%).

division Reaction conditions Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 (c) step Zinc salt: sodium carbonate
Reaction molar ratio 1: 1.3 1: 0.8 1: 1.3 1: 0.6 1: 0.8 1: 1.3 1: 1.3 1: 1.5 Sodium carbonate aqueous solution supply volume flow rate ((L / min) 50 60 70 50 50 100 150 50 pH 7.6 7.6 7.6 6.4 6.4 7.6 7.6 9

<Test Example 1> Quality evaluation of zinc carbonate

1. Preparation of zinc carbonate

Zinc carbonates of Examples 1 to 3 and Comparative Examples 1 to 5 prepared according to Preparation Example 1 were prepared.

2. Method for evaluating the quality of zinc carbonate

The zinc purity of zinc carbonate was measured using an automatic element analyzer (ICP-AES, manufactured by PerkinElmer), the filtration ease was measured in time using a vacuum filter, and the sedimentation property was measured using a 100 ml measuring cylinder. After standing for a minute, the measured water level was settled.

3. Results of zinc carbonate quality evaluation

Table 4 shows the results of evaluating the quality of zinc carbonate. At this time, the determination of the ease of filtration was expressed as ○ when 60 ml / 10 min or more, ** when 50-60 ml / 10 min, and Х when 50 ml / 10 min or less.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 zinc
water(%) 57 57 57 50> 50> 57 57 57 percolation
Ease ○ ○ ○ ○ ○ Х Х Х Sedimentation
(ml / min) 50 60 60 80 80 10 5 5

From Table 4, in the case of zinc carbonate of Comparative Example 1 in which the reaction amount of sodium carbonate is small compared to the preferred reaction molar ratio of zinc salt and sodium carbonate, it can be confirmed that sedimentation is increased and purity is significantly reduced compared to zinc carbonate of Examples 1 to 3, The increase in sedimentation is expected due to the precipitation of unreacted zinc salt in the form of zinc sulfate. When the unreacted zinc salt is precipitated with zinc sulfate, it not only decreases the purity, but also causes a decrease in the whiteness of the final product.

In the production stage of zinc carbonate, the zinc carbonates of Comparative Examples 1 and 2 in which the pH condition was lower than the preferred condition, it was confirmed that the sedimentation property was increased and the purity was significantly reduced compared to the zinc carbonates of Examples 1 to 3.

In the case of the zinc carbonate of Comparative Example 3 and Comparative Example 4, which was introduced in excess of the preferred supply volume flow rate of the sodium carbonate aqueous solution, it was confirmed that the ease of filtration was significantly reduced compared to the zinc carbonate of Examples 1 to 3, Due to this, it can be expected that there is a problem of a process delay and productivity deterioration in the filtration step. In addition, irregular zinc carbonate particles make it difficult to obtain uniform zinc oxide particles in the heat treatment step.

In the case of zinc carbonate of Comparative Example 5 in which the reaction amount of zinc salt was small compared to the preferred reaction molar ratio of zinc salt and sodium carbonate, it was confirmed that sedimentation property was lower than that of zinc carbonate of Examples 1 to 3, but this precipitated fine particles of unreacted carbonate. Due to the result, the progress of filtration is delayed due to the fine size of the solid product.

<Test Example 2> Measurement of the particle shape of zinc carbonate

1. Preparation of zinc carbonate

Zinc carbonates of Example 1 and Comparative Examples 1 to 4 prepared according to Preparation Example 1 were prepared.

2. Method for measuring particle shape of zinc carbonate

The particle shape of the zinc carbonate of Examples 1 and Comparative Examples 1 to 4 was confirmed using a scanning electron microscope (FE-SEM JSM700F, manufactured by JEOL).

3. Result of measuring the particle shape of zinc carbonate

4A to 4E are views showing the results of a scanning electron microscope analysis of zinc carbonate of Comparative Example 1, Comparative Example 2, Example 1, Comparative Example 3, and Comparative Example 4, respectively.

From FIG. 4, the reaction amount of sodium carbonate is small compared to the preferred reaction molar ratio of zinc salt and sodium carbonate, and in the case of zinc carbonate of Comparative Example 1 below the preferred pH range and Comparative Example 2 below the preferred pH range, Example 1 Since zinc carbonate is formed in a plate shape due to precipitation of zinc sulfate, which is an unreacted zinc salt, as compared with that formed in a spherical shape, it can be expected that there is a problem that the purity of a product finally produced by mixing with zinc sulfate is lowered.

In addition, in the case of the zinc carbonates of Comparative Examples 3 and 4 flowing in excess of the desired supply volume flow rate of the sodium carbonate aqueous solution, the zinc carbonates of Example 1 are formed in an irregular size distribution compared to those formed in the uniform size distribution, and thus, in the heat treatment step. It can be expected that it is difficult to form uniform zinc oxide particles.

<Production Example 2> Preparation of zinc oxide powder of Examples 4 to 5 and Comparative Examples 6 to 12

The zinc carbonate of Example 1 prepared according to Preparation Example 1 was put into a rotary incinerator and calcined under a temperature of about 550 ° C. for 15 to 20 minutes to prepare 70 g of zinc oxide powders of Examples 4 to 5 and Comparative Examples 6 to 12. Did. At this time, the reaction conditions of the mass flow rate of the supplied zinc carbonate, the volume flow rate of the supplied oxygen, and the rotational speed are shown in Tables 5 and 6.

division Reaction conditions Example 4 Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 (e)
step Supply zinc carbonate
Mass flow rate (kg / hr) 100 100 40 160 100 Rotation speed (rpm) 5 9 5 5 15 Oxygen supply
Volume flow rate (L / min) 20 20 20 20 20

division Reaction conditions Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 (e)
step Supply zinc carbonate
Mass flow rate (kg / hr) 100 100 100 100 Rotation speed (rpm) 20 5 5 5 Oxygen supply
Volume flow rate (L / min) 20 5 35 40

<Test Example 3> Quality evaluation of zinc oxide powder

1. Preparation of zinc oxide powder

Zinc oxide powders of Examples 4 to 5 and Comparative Examples 6 to 12 prepared according to Preparation Example 2 were prepared.

2. Method for evaluating the quality of zinc oxide powder

The zinc oxide purity of the zinc oxide powder was measured using an automatic element analyzer (ICP-AES, manufactured by PerkilnElmer), and the specific surface area was measured using a specific surface area measuring device (Tristar, manufactured by Micromeritics), and yellowness (b -value) was measured using a chromatic colorimeter (CR-200, manufactured by MINOLTA).

3. Quality evaluation result of zinc oxide powder

Table 7 shows the results of evaluating the quality of the zinc oxide powder.

division Example 4 Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Zinc oxide purity (%) 98 ~ 99 98 ~ 99 97 ~ 99 95 ~ 99 90 ~ 99 98 ~ 99 97 ~ 99 97 ~ 99 97 ~ 99 Specific surface area (m ² / g) 25 ~ 30 25 ~ 30 25 ~ 30 25 ~ 40 25-50 25 ~ 30 25 ~ 30 25 ~ 30 25 ~ 30 Yellowness
(b-value) 1.5 1.5 2.5 1.5 2.5 3.5 1.5 1.5 1.5

From Table 7, the zinc oxide powder of Comparative Example 6 in which the mass flow rate of zinc carbonate supplied to the rotary incinerator is less than the preferred range, the yellowness (b-value) is increased compared to the zinc oxide powder of Examples 4 and 5 , It can be seen that the whiteness was lowered.

In the case of the zinc oxide powder of Comparative Example 7 in which the mass flow rate of zinc carbonate supplied to the rotary incinerator exceeds a desirable range, the zinc oxide purity range and specific surface area range are wider than those of Example 4 and Example 5 It can be seen that the yellowness is increased and the whiteness is decreased.

In the case of the zinc oxide powder of Comparative Example 8 in which the rotational speed of zinc carbonate in the rotary incinerator exceeds a desirable range, the zinc oxide powder of Examples 4 and 5 shows a broader distribution and a higher yellowness, It can be confirmed that the whiteness decreased. In addition, in the case of the zinc oxide powder of Comparative Example 9 in which the rotational speed of zinc carbonate in the rotary incinerator significantly exceeds a desirable range, the yellowness is higher and the whiteness is lower than that of the zinc oxide powders of Examples 4 and 5 Can be confirmed.

Zinc oxide powder of Comparative Example 10 in which the volumetric flow rate of oxygen supplied to the rotary incinerator is less than a preferred range, Comparative Example 11 in which the volumetric flow rate of oxygen supplied to the rotary incinerator exceeds a desirable range, and zinc oxide of Comparative Example 12 significantly exceeding In the case of the powder, it can be confirmed that the zinc oxide purity range of the zinc oxide powders of Examples 4 and 5 shows a wide distribution. From this, it can be expected that if the volume flow rate of the supplied oxygen is outside the desired range, the temperature variation for each section of the rotary incinerator is widely distributed, resulting in a decrease in uniformity and a deviation in purity during heat treatment. In addition, although not shown in Table 7, in the process of preparing the zinc oxide powders of Comparative Examples 11 and 12, excessive dust was generated.

<Production Example 3> Preparation of zinc oxide powder of Example 4 and Comparative Examples 13-15

Oxidation of Comparative Examples 13 to 15 under the same reaction conditions as in Example 4, except that the zinc carbonate of Example 1 prepared in Preparation Example 1 was put in a rotary incinerator and calcined under temperatures of 400, 700 and 900 ° C, respectively. 70 g of zinc powder was prepared.

<Test Example 4> Measurement of particle shape and size of zinc oxide powder

1. Preparation of zinc oxide powder

The zinc oxide powder of Example 4 prepared according to Preparation Example 2, and the zinc oxide powders of Comparative Examples 13 to 15 prepared according to Preparation Example 3 were prepared.

2. Method for measuring particle shape and size of zinc oxide powder

The particle shape of the zinc oxide powder of Examples 4 and 13 to 15 was confirmed using a scanning electron microscope, and the particle size of the zinc oxide powder of Examples 4 and 13 to 15 was an energy dispersive X-ray analyzer ( It was confirmed using HP-Powder XRD D8 ADVANCE, manufactured by Bruker).

3. Result of measuring particle shape and size of zinc oxide powder

5 is a view showing the results of the scanning electron microscope analysis and the transmission electron microscope analysis of the zinc oxide powder according to an embodiment of the present invention. Figure 5a is a view showing the zinc oxide powder of Example 4 calcined to 550 ℃, Figures 5b, 5c and 5d are views showing the zinc oxide powder of Comparative Examples 13 to 15 calcined to 400, 700 and 900 ℃, respectively .

From FIG. 5, when the calcination temperature is less than a desirable range, nano-class product implementation is possible, but the purity is lowered, and there is a limit in application in the application of the finally produced product due to the high specific surface area, and the calcination temperature is desirable. When it exceeds the range, it can be confirmed that it is difficult to implement nano-type zinc oxide powder due to increased grain growth, and it is difficult to implement desired properties.

<Test Example 5> X-ray diffraction analysis results of the surface coated zinc oxide powder

1. Preparation of surface coated zinc oxide powder

According to the preparation method described above, 100 g of the zinc oxide powder of Example 4 and 3.5 g of n-octyl triethoxy silane, a silicone-based surface treatment agent, were mixed in 500 ml of isopropyl alcohol, an organic solvent, to prepare a mixed solution. The prepared mixed solution was wet-milled by a bead mill (Mechstar, manufactured by DAESUNG CHEMICAL IND) to form a pulverized product, and then the pulverized product was dried in a vacuum oven at 60 to 80 ° C for 120 hours to separate the solid material. The separated solid was dry pulverized by air-jet mill (Jet mill 200DSM, manufactured by DAESUNG CHEMICAL IND) to prepare 70 g of the surface-coated high purity nano zinc oxide powder of Example 6.

2. Surface coated zinc oxide powder X-ray diffraction analysis method

X-ray diffraction of the surface-coated zinc oxide powder of Example 6 was analyzed using an energy dispersive X-ray analyzer (HP-Powder XRD D8 ADVANCE, manufactured by Bruker).

3. Surface coated zinc oxide powder X-ray diffraction analysis  result

Figure 6 is a view showing the results of X-ray diffraction analysis of the surface-coated zinc oxide powder according to Example 6 of the present invention, the surface-coated zinc oxide powder prepared by the method of the present invention is dense hexagonal made of oxygen It can be confirmed that half of the tetrahedral sites of the Hexagonal Close Packed Lattice (HCP) have a wurtzite structure made of zinc metal.

<Test Example 6> Analysis result of the transmission electron microscope analysis of the surface coated zinc oxide powder

One. Surface coated zinc oxide powder  Preparations

100 g of the surface-coated high-purity nano zinc oxide powder of Example 6 prepared and used in Test Example 5 was used.

2. Method for analyzing transmission electron microscope of surface-coated zinc oxide powder

The transmission electron microscope analysis of the surface-coated zinc oxide powder of Example 6 was confirmed using a transmission electron microscope (HR TEM Ⅱ JEM-2100F, manufactured by JEOL).

3.  Transmission electron microscope analysis of surface coated zinc oxide powder

7 is a view showing a scanning electron microscope analysis result and a transmission electron microscope analysis result of the surface-coated zinc oxide powder according to Example 6 of the present invention, according to FIG. 7, the surface coating prepared by the manufacturing method of the present invention It can be seen that the coated thickness of the zinc oxide powder was uniformly formed as 2 to 5 nm.

Although the invention has been described in connection with the preferred embodiments mentioned above, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will include such modifications or variations as long as they fall within the spirit of the invention.

Claims (16)

(A) preparing a mixed solution by dissolving zinc by-products in an acidic solution;
(b) removing impurities from the mixed solution prepared in step (a);
(c) reacting by adding an aqueous sodium carbonate solution to the mixed solution from which impurities were removed by the step (b);
(d) filtering and separating basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) produced by the reaction of step (c); And
(e) The method of preparing a high purity nano zinc oxide powder comprising the step of calcining the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) in a rotary incinerator. The method of claim 1, wherein the step (b),
(b1) a primary filtration step of removing the slag contained in the mixed solution prepared in step (a);
(b2) a second filtration step of removing the metal ion hydroxide produced by adding an oxidizing agent and a neutralizing agent to the mixed solution from which the slag is removed by the step (b1); And
(b3) characterized in that it comprises a third filtration step of removing the metal particles generated by adding a reducing agent to the mixed solution from which the metal ion hydroxide is removed by the step (b2), a method for producing a high purity nano zinc oxide powder . According to claim 2,
The oxidizing agent added in step (b2) is a group consisting of hydrogen peroxide, urea hydrogen peroxide, permanganic acid, permanganate, sulfate, persulfate, perchloric acid, perchlorate, hypochlorous acid, hypochlorite, periodic acid, periodate, and mixtures thereof Method for producing a high purity nano zinc oxide powder, characterized in that at least one selected from. According to claim 2,
The (b2) step of the oxidizing agent is characterized in that it is added in 0.5 to 1 part by weight compared to 100 parts by weight of the slag is removed by the step (b1), high purity nano zinc oxide powder manufacturing method. The method of claim 2
The reducing agent in the step (b3) is zinc powder, potassium permanganate, hydrazine, hydroquinone, sodium borohydride, hexamethylenetetramine, alkylamine, alkylenediamine, alkylenetriamine, alkylenetetramine and their Method of producing a high purity nano zinc oxide powder, characterized in that at least one selected from the group consisting of a mixture. The method of claim 2
The reducing agent in the step (b3) is characterized in that the metal ion hydroxide is removed by the step (b2), characterized in that added in 0.5 to 1 part by weight compared to 100 parts by weight of the mixed solution, the method for producing high purity nano zinc oxide powder. According to claim 1,
The (c) step of the sodium carbonate aqueous solution is characterized in that is added at a volume flow rate of 30 ~ 70 L / min, high purity nano zinc oxide powder manufacturing method. According to claim 1,
Preparation of high purity nano zinc oxide powder, characterized in that the reaction molar ratio of zinc salt contained in the mixed solution from which impurities are removed by step (b) and the sodium carbonate of step (c) is 1: 0.8 to 1.3 Way. According to claim 1,
In the step (e), characterized in that oxygen is introduced into the rotary incinerator at a volume flow rate of 10 to 30 L / min, a method for producing high purity nano zinc oxide powder. According to claim 1,
In the step (e), characterized in that the separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) is introduced into the rotary incinerator at a mass flow rate of 50 to 150 kg / hr, of high purity nano zinc oxide powder. Manufacturing method. According to claim 1,
The separated basic zinc carbonate (ZnCO ₃ · Zn (OH) ₂ ) in the rotary incinerator in step (e) is characterized in that it is calcined while rotating at a rotational speed of 1 to 9 rpm, of high purity nano zinc oxide powder. Manufacturing method. (A) preparing a mixed solution by mixing the zinc oxide powder and the surface treatment agent prepared by the method for producing a high purity nano-zinc oxide powder according to any one of claims 1 to 11 with an organic solvent;
(b) wet grinding the mixed solution prepared in step (a) to form a pulverized product;
(C) separating the solid by vacuum drying the pulverized material; And
(D) a method of manufacturing a surface-coated high purity nano zinc oxide powder comprising the step of dry grinding the solid. The method of claim 12,
The surface treatment agent of step (a) is an alkyl acrylate copolymer methylpolysiloxane ester (Alkyl Acrylate Copolymer Methylpolysiloxane Ester), stearic acid (Stearic Acid), n-octyl triethoxy silane (n-Octyl Triethoxy Silane), methylhydrogenpolysiloxane (Methylhydrogenpolysiloxane), methylpolysiloxane (Methylpolysiloxane), dimethylpolysiloxane (Dimethylpolysiloxane) methylphenylpolysiloxane (Methylphenylpolysiloxane), hydroxy terminated dimethylpolysiloxane (Hydroxy Terminated Dimethylpolysiloxane), and characterized in that at least one member selected from the group consisting of , Surface-coated high purity nano zinc oxide manufacturing method. The method of claim 12,
Zinc oxide powder and the surface treatment agent of the step (a) is characterized in that added in a weight ratio of 100: 2 to 5, the method for producing a surface-coated high purity nano zinc oxide powder. The method of claim 12,
The organic solvent of step (a) is at least one selected from the group consisting of benzene, toluene, xylene, N-methyl-2-pyrrolidone, ethyl N-hydroxymethylpyrrolidone-2 acetate and mixtures thereof. Characterized in that, the method for producing a surface-coated high purity nano zinc oxide powder. The method of claim 12,
The step (b) is characterized in that is performed for 2 to 5 hours at 25 ~ 50 ℃, the method for producing a surface-coated high purity nano zinc oxide powder.

Images