KR100734178B1 - Process for preparing zinc oxide powder - Google Patents

Abstract

Provided is a process for preparing zinc oxide powder with uniform particle size through a single-step of surface treatment and the preparation of zinc oxide, to thereby simplify the overall process. The process for preparing zinc oxide powder comprises the steps of: mixing 5-10wt.% silicon group surface treatment agent and 0.5-1.5wt% of binder in presence of 100wt.% of an organic solvent, and blending the resulting solution with 300-700wt% acidic solution; neutralizing, at 10-20 deg.C, the acidic mixture by slowly adding an alkaline solution at speed of 0.5-1.0wt.%/min with respect to a total quantity of the alkaline solution to be added; and performing a hydrothermal process at 80-100deg.C for 20-30 hours. The alkaline solution is used at an amount of 500-1000wt.% of 100wt.% of the organic solvent.

Description

Process for preparing Zinc Oxide powder

1 is a graph showing the XRD analysis of the zinc oxide powders obtained in Example 1 and Comparative Example 1,

2 is a SEM photograph of the zinc oxide powder obtained in Example 1, which is an embodiment of the present invention;

3 is a SEM photograph of the zinc oxide powder obtained in Comparative Example 1,

4 is a SEM photograph of the zinc oxide powder obtained in Comparative Example 1,

5 is a photograph showing the results of measuring the water repellency of the zinc oxide powders obtained in Example 1 and Comparative Example 1.

The present invention relates to a method for producing zinc oxide powder.

Recently, as the destruction of the ozone layer due to environmental pollution increases, not only is it an environmental problem, but as a result, an excessive exposure to ultraviolet rays increases premature aging of the skin, skin cancer, etc., and accordingly, interest in sunscreens is also increasing.

Generally, sunscreens used in cosmetics are classified into organic sunscreens and inorganic sunscreens. As organic sunscreens, parsol MCX having a conjugation bond capable of absorbing ultraviolet light in its molecular structure. The main type of chemicals (chemical name: Octyl methoxycinnamate) UV absorber. However, Pasol MCX, an organic sunscreen, has disadvantages such as skin toxicity, allergies, and discoloration. Recently, inorganic sunscreens are used instead of organic sunscreens.

On the other hand, the inorganic sunscreen mainly has a sunscreen effect by the ultraviolet absorption and scattering, typical inorganic sunscreens are metal oxides having high refractive index TiO ₂ , CeO ₂ , ZnO Etc. are used. The refractive index of the sunscreen is shown in Table 1 below.

White pigment Refractive index SiO ₂ 1.55 TiO ₂ , rutile 2.76 TiO ₂ , anatase 2.55 ZnO 2.02 ZrO ₂ 2.40 ZnS 2.37 BaSO ₄ 1.64 CaSO ₄ 1.59

Among them, zinc oxide is widely used in pigments, industrial drugs, pharmaceuticals, and cosmetics because the particles are fine, nontoxic and white. In particular, recently, cosmetics have been increasing the amount of zinc oxide for the purpose of blocking long-wavelength ultraviolet rays (UV-A region) for the sunscreen effect.

At this time, the zinc oxide contained in the particles is preferably uniform to be evenly dispersed when included in the cosmetic.

Generally, when zinc oxide powder is mixed with cosmetics such as an emulsified sunscreen cosmetic, zinc oxide powder obtained by producing zinc oxide powder and then hydrophobizing the surface thereof is used.

However, when manufacturing the zinc oxide powder by the same method as in the prior art, there was a limit in preparing the zinc oxide powder of uniform particles, and there is a problem in that the economical efficiency in the manufacturing process because of the separate surface treatment.

Accordingly, the inventors have confirmed through experiments that zinc oxide powder of uniform particles can be produced while producing a surface treatment in a single process simultaneously with the production of zinc oxide, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a method for producing zinc oxide powder, which simultaneously prepares zinc oxide and surface treatments in a single process.

It is another object of the present invention to provide a method for producing zinc oxide powder which can provide zinc oxide powder of uniform particles.

The present invention for achieving the above object is mixed with 5 to 10 parts by weight of the silicon-based surface treatment agent and 0.5 to 1.5 parts by weight of the binder with respect to 100 parts by weight of the organic solvent, and put it in 300 to 700 parts by weight of an acid solution containing zinc Mixing step of uniformly mixing; Adding an alkaline solution to the mixed solution, but neutralizing step of slowly adding the alkaline solution at a rate of 0.5 to 1.0 wt% / min relative to the total weight of the alkaline solution so as not to exceed 20 ° C .; And it provides a method for producing zinc oxide powder comprising a hydrothermal synthesis step of reacting for 20 to 30 hours at 80 ~ 100 ℃.

The neutralization step is characterized in that the temperature is maintained at 10 ~ 20 ℃.

The silicone-based surface treatment agent is an alkyl acrylate copolymer methylpolysiloxane ester, stearic acid, n-octyl triethoxy silane, methylhydrogenpolysiloxane, methylhydrogenpolysiloxane, It is characterized in that at least one member selected from the group consisting of dimethylpolysiloxane (Dimethylpolysiloxane), methylphenylpolysiloxane (Methylphenylpolysiloxane), hydroxy terminated dimethylpolysiloxane (mixture thereof).

The acid solution is characterized in that at least one selected from zinc chloride aqueous solution, zinc nitrate aqueous solution, zinc sulfate aqueous solution and zinc acetate aqueous solution.

The alkaline solution is characterized in that at least one selected from sodium hydroxide solution, potassium hydroxide solution, ammonium hydroxide solution and sodium carbonate solution.

The alkaline solution is characterized by using 500 to 1000 parts by weight based on 100 parts by weight of the organic solvent.

Hereinafter, the present invention will be described in more detail.

First, in order to prepare the zinc oxide powder of the present invention, a silicon surface treatment agent and a binder are dissolved in an organic solvent. The content is 5 to 10 parts by weight of the silicon-based surface treatment agent and 0.5 to 1.0 parts by weight of the binder with respect to 100 parts by weight of the organic solvent is the optimum condition for bonding the zinc oxide and silicon-based surface treatment agent.

The silicone-based surface treatment agent is not particularly limited, alkyl acrylate copolymer Methylpolysiloxane ester, stearic acid, n-octyl triethoxy Silane, methylhydro It is preferable to use at least one selected from the group consisting of methylhydrogenpolysiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, hydroxy terminated dimethylpolysiloxane and mixtures thereof.

As the coupling agent, a commonly known one may be used, and a silane system such as aminoethylaminopropyltriethoxysilane may be used.

As the organic solvent, alcohols such as methanol, ethanol and isopropyl alcohol are preferably used.

The mixed solution mixed as described above is added to an acid solution containing zinc such as zinc chloride aqueous solution, zinc nitrate aqueous solution, zinc sulfate aqueous solution and zinc acetate aqueous solution, and the like to prepare a uniform mixed solution while stirring until the insoluble matter disappears.

The acid solution containing zinc is preferably used in an amount of 300 to 700 parts by weight based on 100 parts by weight of the organic solvent.

As described above, the present invention was a two-step manufacturing process in which a silicon oxide surface treatment agent was mixed with a reaction raw material in the manufacture of zinc oxide and surface treated simultaneously with the production of zinc oxide. It can be shortened to a one-step manufacturing process.

While stirring the mixed solution at 250 ~ 300rpm, the alkaline solution is gradually added to neutralize. At this time, the alkaline solution is slowly added at a rate of 0.5 to 1.0% by weight relative to the total weight of the alkaline solution so that the temperature of the solution does not exceed 20 ° C. The temperature of the solution is more preferably 10 to 20 ° C. If it is less than 10 ℃ zinc hydroxide formation is too slow, and if the temperature exceeds 20 ℃ zinc oxide is formed non-uniformly, there is a problem that it is difficult to control the particle size of the zinc oxide powder.

Since the heat is generated during the neutralization reaction, in addition to controlling the speed of the alkaline solution to be added, it is also possible to control the temperature using a cooler.

As the alkaline solution, one or more selected from sodium hydroxide solution, potassium hydroxide solution, ammonium hydroxide solution and sodium carbonate solution may be used. The alkali solution is preferably used in an amount of 500 to 1000 parts by weight based on 100 parts by weight of the organic solvent in consideration of pH.

After the addition of alkaline solution is completed, the reactor is sealed and hydrothermally synthesized at 80 to 100 ° C for 20 to 30 hours.

After the reaction is completed, the mixture is cooled to about 40 ~ 50 ℃ to separate the powder and the liquid using a filter, and the sodium chloride formed during the reaction by washing with distilled water.

The obtained powder is dried using a dryer until the moisture content is 1% or less, and ground to a size of 100 to 200 nm using a grinder.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

<Example 1>

3 mol (408.0 g) of zinc chloride (ZnCl ₂ ) is dissolved in 900 ml of water to form an aqueous zinc chloride solution. 12.0564 g of n-Octyl Triethoxy Silane and 1.95 g of aminoethylaminopropyl triethoxy silane are dissolved in 210 ml of isopropyl alcohol and mixed in an aqueous zinc chloride solution. The mixed solution is placed in a 3 L reactor and made into a homogeneous mixed solution while stirring until there is no insoluble matter.

While stirring the solution at 250-300 rpm, a solution of 6 mol (240 g) of sodium hydroxide (NaOH) in 1300 ml of water was gradually neutralized by adding 6.5 to 13.0 ml / min at a rate not to exceed 20 degrees. Thereafter, the reactor is reacted at 85 ° C. for 24 hours in a sealed state.

After the reaction was completed, cooled to 40 ~ 50 ℃ to separate the powder and liquid by using a filter, 500ml of distilled water to wash the sodium chloride.

The powder obtained is dried in a vacuum dryer for 24 to 48 hours until the moisture content is less than 1%. The dried powder is ground to a size of 100 ~ 200 nm using a grinder.

<Example 2>

3 mol (408.0 g) of zinc chloride (ZnCl ₂ ) is dissolved in 900 ml of water to form an aqueous zinc chloride solution. 12.0564 g of n-Octyl Triethoxy Silane and 1.95 g of aminoethylaminopropyl triethoxy silane are dissolved in 210 ml of isopropyl alcohol and mixed in an aqueous zinc chloride solution. The mixed solution is placed in a 3 L reactor and made into a homogeneous mixed solution while stirring until there is no insoluble matter.

While stirring the solution at 250-300 rpm, a solution of 6 mol (336 g) of potassium hydroxide (KOH) in 1300 ml of water was gradually neutralized by adding 6.5 to 13.0 ml / min at a rate such that the temperature of the reactant was not more than 20 degrees. Thereafter, the reactor is reacted at 85 ° C. for 24 hours in a sealed state.

After the reaction was completed, cooled to 40 ~ 50 ℃ to separate the powder and liquid using a filter, 500ml of distilled water to wash the potassium chloride.

The powder obtained is dried in a vacuum dryer for 24 to 48 hours until the moisture content is less than 1%. The dried powder is ground to a size of 100 ~ 200 nm using a grinder.

<Example 3>

3 mol (408.0 g) of zinc chloride (ZnCl ₂ ) is dissolved in 900 ml of water to form an aqueous zinc chloride solution. 12.0564 g of n-Octyl Triethoxy Silane and 1.95 g of aminoethylaminopropyl triethoxy silane are dissolved in 210 ml of isopropyl alcohol and mixed in an aqueous zinc chloride solution. The mixed solution is placed in a 3 L reactor and made into a homogeneous mixed solution while stirring until there is no insoluble matter.

While stirring this at 250-300 rpm, a solution of 3 mol (318 g) of sodium carbonate (Na ₂ CO ₃ ) in 1300 ml of water is gradually neutralized by adding a solution at a rate of 6.5 to 13.0 ml / min so that the temperature of the reactant does not exceed 20 degrees. Thereafter, the reactor is reacted at 85 ° C. for 24 hours in a sealed state.

After the reaction was completed, cooled to 40 ~ 50 ℃ to separate the powder and liquid by using a filter, 500ml of distilled water to wash the sodium chloride.

The powder obtained is dried in a vacuum dryer for 24 to 48 hours until the moisture content is less than 1%. The dried powder is ground to a size of 100 ~ 200 nm using a grinder.

<Example 4>

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except for using dimethylpolysiloxane instead of n-Octyl Triethoxy Silane.

Example 5

Nano-size zinc oxide was prepared in the same manner as in Example 1 except that methylhydrogenpolysiloxane was used instead of n-Octyl Triethoxy Silane.

<Example 6>

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except that hydroxy terminated dimethypolysiloxane was used instead of n-Octyl Triethoxy Silane.

<Example 7>

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except that stearic acid was used instead of n-octyl triethoxy silane.

<Example 8>

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except that zinc nitrate (Zn (NO ₃ ) ₂ ) was used instead of zinc chloride (ZnCl ₂ ).

Example 9

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except that zinc sulfate (ZnSO ₄ ) was used instead of zinc chloride (ZnCl ₂ ).

<Example 10>

Nano-sized zinc oxide was prepared in the same manner as in Example 1 except that zinc acetate (Zn (CH ₃ COO) ₂ ) was used instead of zinc chloride (ZnCl ₂ ).

Comparative Example 1

In Example 1, the sodium hydroxide solution was added at a rate of 25 ml / min without rate control during neutralization, and zinc oxide powder was prepared in the same manner except that the temperature was raised to 30 ° C.

Comparative Example 1

3 mol (408.0 g) of zinc chloride (ZnCl ₂ ) is dissolved in 900 ml of water to form an aqueous zinc chloride solution. The solution is placed in a 3 L reactor and made into a homogeneous mixed solution with stirring until there are no insolubles.

While stirring at 250 to 300 rpm, a solution of 6 mol (240 g) of sodium hydroxide (NaOH) in 1300 ml of water was added to the reactant at a rate of 20 to 30 ml / min without temperature control and neutralized. Thereafter, the reactor is reacted at 85 ° C. for 24 hours in a sealed state.

After the reaction was completed, cooled to 40 ~ 50 ℃ to separate the powder and liquid by using a filter, 500ml of distilled water to wash the sodium chloride.

The powder obtained is dried in a vacuum dryer for 24 to 48 hours until the moisture content is less than 1%. The dried powder is ground to a size of 100 ~ 200 nm using a grinder.

2,100 ml of distilled water was added to 240 g of dried zinc oxide powder (A solution), 12.0564 g of n-Octyl Triethoxy Silane and 1.95 g of aminoethylaminopropyl triethoxy silane Is dissolved in 210ml of isopropyl alcohol (B solution) and mixed with A solution.

The reaction is carried out at 80 ° C. for 24 hours while the reactor is sealed while stirring at 250 to 300 rpm.

After the reaction is completed, the mixture is cooled to 40-50 ° C., and the powder and the liquid are separated using a filter.

The powder obtained is dried in a vacuum dryer for 24 to 48 hours until the moisture content is less than 1%. The dried powder is ground to a size of 100 ~ 200 nm using a grinder.

Physical properties were evaluated using the zinc oxide powders obtained in Examples and Comparative Examples as follows.

(1) XRD analysis

The zinc oxide powders obtained in Example 1 and Comparative Example 1 were analyzed using an XRD analyzer (manufacturer: RIGAKU, model name: DMAX 2500), and the results are shown in FIG. 1.

As a result, it can be seen that there is no difference in the components of the zinc oxide powders obtained in Examples and Comparative Examples.

(2) UV protection index

The UV protection index of the zinc oxide powders obtained in Examples 1 to 10, Comparative Example 1 and Comparative Example 1 was obtained by applying 1 mg / cm 2 using a UV protection index analyzer (manufacturer: OPTOMETRICS, model name: SPF 290 S). It measured, and the result is shown in Table 2.

division SUN PROTECTION FACTOR (SPF) Example 1 78 Example 2 79 Example 3 78 Example 4 80 Example 5 80 Example 6 77 Example 7 78 Example 8 79 Example 9 78 Example 10 80 Comparative Example 1 71 Comparative Example 1 76

As a result, it can be seen that the zinc oxide powders obtained in Examples 1 to 10 are excellent in UV protection index, which is equivalent to or more than that of Comparative Example 1, in which the surface treatment was separately performed, even if the surface treatment was not separately performed.

In addition, although the surface treatment was not performed separately, it can be seen that the UV blocking index is low in Comparative Example 1 in which the rate of addition of the alkaline solution is not controlled.

The UV blocking index is also related to the particle size of the zinc oxide powder. When the particle size is small, the UV blocking index is high because the area covered by the same amount is large. From this, the zinc oxide powder prepared in the embodiment according to the present invention can be seen that the particle size is small and uniformly formed even after the grinding step only once without undergoing the surface treatment step separately, and thus the zinc oxide prepared according to the present invention. When the powder is used, it is not necessary to increase the amount of zinc oxide used in order to increase the UV blocking effect.

(3) SEM measurement

Using the SEM (manufacturer: HITACHI, model name: S-4700) was taken in the form of the zinc oxide powder prepared in Example 1, Comparative Example 1 and Comparative Example 1, the results are shown in Figures 2, 3 and Same as 4.

As a result, the zinc oxide powder according to the present invention had a uniform particle size and was not agglomerated, whereas the zinc oxide powder prepared by Comparative Example 1 did not have a uniform particle size, and the zinc oxide powder according to Comparative Example 1 had a uniform particle size. You can see it stuck together.

(4) particle size distribution

Particle size distribution was measured by using the MASTERSIZER 2000 of MALVERN company, the results are shown in Table 3 below.

division Particle size distribution Example 1 173 nm Example 2 175 nm Example 3 173 nm Example 4 178 nm Example 5 171 nm Example 6 180 nm Example 7 176 nm Example 8 181 nm Example 9 183 nm Example 10 177 nm Comparative Example 1 285 nm Comparative Example 1 245 nm

As a result of the particle size analysis, Examples 1 to 10 obtained a small particle size distribution, but Comparative Example 1 and Comparative Example 1 can be seen that a large particle size distribution was obtained compared to the examples. From this, it can be seen that the zinc oxide powder obtained from the examples according to the present invention has uniform particles.

(5) Water repellant power

Water repellency was measured by putting 10 g of zinc oxide powder in 100 ml of distilled water and cutting off at 100 ° C. for 10 minutes.

The results measured as described above are shown in FIG. 4.

As a result of measuring the water repellency, the zinc oxide prepared in Example 1 hardly produced precipitated zinc oxide, but Comparative Example 1 could visually confirm that a large amount of zinc oxide was precipitated.

As described above, the present invention can manufacture the zinc oxide and the surface treatment at the same time in a single process, the manufacturing process is simple compared to the existing method can save the manufacturing process cost, uniform surface treatment by a single process There is an advantage to the surface coating.

In addition, the present invention can prepare a zinc oxide powder having a small particle size and uniform particle size distribution by controlling the rate of addition of the alkaline solution.

In addition, the present invention has the advantage that it is not necessary to increase the amount of zinc oxide used in order to increase the UV blocking effect to produce a zinc oxide powder having a small and uniform particle size and excellent physical properties such as UV protection index by a simple manufacturing process.

Claims (6)

A mixing step of mixing 5-10 parts by weight of the silicon-based surface treating agent and 0.5-1.5 parts by weight of the binder with respect to 100 parts by weight of the organic solvent, and putting the same in an acid solution containing zinc in 300-700 parts by weight; Adding an alkaline solution to the mixed solution, but neutralizing step of slowly adding the alkaline solution at a rate of 0.5 to 1.0 wt% / min relative to the total weight of the alkaline solution so as not to exceed 20 ° C .; And Hydrothermal synthesis step of reacting at 80 to 100 ° C. for 20 to 30 hours; Method for producing a zinc oxide powder comprising a. The method of claim 1, The neutralization step is a method for producing zinc oxide powder, characterized in that the temperature is maintained at 10 ~ 20 ℃. The method of claim 1, The silicone-based surface treatment agent is an alkyl acrylate copolymer methylpolysiloxane ester, stearic acid, n-octyl triethoxy silane, methylhydrogenpolysiloxane, methylhydrogenpolysiloxane, Dimethyl polysiloxane (Dimethylpolysiloxane), methylphenyl polysiloxane (Methylphenylpolysiloxane), hydroxy terminated dimethylpolysiloxane (hydroxy terminated dimethylpolysiloxane) A method for producing zinc oxide powder, characterized in that at least one selected from the group consisting of. The method of claim 1, The acid solution is a method for producing zinc oxide powder, characterized in that at least one selected from zinc chloride aqueous solution, zinc nitrate aqueous solution, zinc sulfate aqueous solution and zinc acetate aqueous solution. The method of claim 1, The alkaline solution is a method for producing zinc oxide powder, characterized in that at least one selected from sodium hydroxide solution, potassium hydroxide solution, ammonium hydroxide solution and sodium carbonate solution. The method of claim 1, The alkaline solution is used in the production of zinc oxide powder, characterized in that 500 to 1000 parts by weight based on 100 parts by weight of the organic solvent.

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