KR20100115201A - Nano-silver controled particles size and preparing thereof - Google Patents

Abstract

PURPOSE: Nano silver with controlled particle size and a preparing method thereof are provided to make nano silver from a stable colloidal nano-silver solution in which nano silver particles are evenly distributed. CONSTITUTION: A method for preparing nano silver with controlled particle size comprises steps of: dissolving silver nitride liquid in the water, adding laponite RDS and a reducing agent in the silver nitrate solution, agitating the colloidal nano-silver solution at a temperature of 25~100°C and a pressure of 10~250 Psi in a high pressure reactor, and then drying the colloidal nano-silver solution with a freeze-drying machine.

Description

Nano silver controlled particle size and preparing method

The present invention relates to a method for producing nano silver and to a nano silver and a method for producing the particle size controlled using a dispersing agent and a reducing agent.

With the development of science and technology, silver is now nano-sized and used in various applications such as refrigerators, air purifiers, toothpastes, soaps, and cosmetics. These nano silvers generally have bactericidal properties that release anions to the extent that they sterilize various germs and inhibit invasion of bacteria, and are antibacterial that inhibit the growth and development of various viruses and bacteria, and deodorant which adsorbs and decomposes unpleasant odors. There is this. In addition, it has an excellent self-cleaning ability to decompose and remove the electromagnetic wave blocking effect and fungi.

As such, the use of nanosilver is being expanded to a wide field, and thus many nanosilver are manufactured.

There are various methods for producing nano silver, but they can be generally divided into a top-down method (physical method) and a bottom-up method (chemical method).

The top-down method is a method of making micro-particles into nano-sized particles. This method has the advantage of easily controlling the size of nanoparticles by slicing bulk materials, but having a uniform size during particle manufacturing. There is a lot of practical limitations in synthesizing particles with and.

On the other hand, the bottom-up method is mainly performed through colloidal solution phase synthesis through chemical molecules or atomic precursors, and is suitable for producing uniform particles, shapes, and structures. It is known that it is much more advantageous for producing nano-sized particles because it starts from the agglomerated atoms in the gas or solution phase. However, when the nano silver is manufactured by the conventional bottom-up method, a large amount of dispersant must be used to prevent aggregation of small nano-sized particles, which increases production costs and causes problems in productivity.

In the case of producing the nano silver, aggregation due to the surface self-reactivity unique to the nano-response caused a problem in the uniformity and control of the particle size. Therefore, in order to solve these problems, methods using various dispersants and chemical reduction methods have been disclosed. These techniques have been proposed as a method of adding a dispersant to an aqueous silver solution and using a buffer solution to control the pH. However, such a method also has a difficulty in producing high concentration nano silver particles of cohesive or precipitated and fine and uniform size.

In addition, Korean Patent Publication No. 2000-0012423 discloses a method of preparing silver nanoparticles using polyoxyethylene sorbitan monolaurate as a dispersant and hydrazine as a reducing agent. However, the nano silver prepared in this way can be manufactured to a particle size of less than 300nm, but there is a disadvantage that can not control the size of the particle.

In addition, the Republic of Korea Patent Publication No. 2005-0040226 and the step of forming a complex ion by adding ammonium hydroxide; After the dispersing agent was added to prepare a mono-dispersed sol (silver) silver nanoparticles, the pH was adjusted to basic conditions with sodium hydroxide, and then a method of producing nano silver through a step of reducing formaldehyde and have. However, such a method uses sodium hydroxide as a pH buffer solution and is prepared by controlling the size of the nano silver particles by controlling the amount of dispersant, but there is a disadvantage in that the size of the particles cannot be accurately identified.

Therefore, in the production of nano silver, it is possible to evenly disperse the nanoparticles, and a method for producing a nano silver colloid solution of high concentration to produce a nano particle with a uniform particle size is desired.

In order to solve the above problems, the present invention has an object to reduce the manufacturing cost in manufacturing nano silver.

It is also an object of the present invention to prepare a nano silver colloidal solution in which the particles are stable by preventing the aggregation or precipitation of the nano silver particles.

It is also an object of the present invention to provide a nano silver colloidal solution in which nano silver particles can be uniformly dispersed in a colloidal solution state.

In addition, an object of the present invention is to control the size of the nano silver particles to produce a nano silver of the desired size.

In order to achieve the above object, the present invention is a nano silver colloid solution made by dissolving a silver nitrate solution in water and adding an inorganic dispersant Laponite RDS and a reducing agent in a high pressure reactor 25 to 100 ℃ temperature and 10 to Nanoparticles with controlled particle size controlled by drying at a pressure of 250 Psi are provided.

The present invention also provides nano silver having a controlled particle size, characterized in that the concentration of the silver nitrate solution is from 0.01 to 10 mol / L.

In another aspect, the present invention provides a nano-silver of the particle size is controlled in which the amount of the inorganic dispersant Laponite RDS is added in a molar ratio of silver nitrate and inorganic dispersant 1: 1 to 1: 3.

The present invention also provides nano silver having a controlled particle size by adding sodium borohydride or hydrazine as the reducing agent.

In another aspect, the present invention provides a nano-silver of the particle size is controlled in which the amount of the reducing agent is added in a molar ratio of the silver nitrate and the reducing agent is 1: 2 to 1:10.

In another aspect, the present invention is to prepare a nano-silver particles, dissolving the silver nitrate solution in water to make a silver salt aqueous solution; Adding an inorganic dispersant laponite RDS to the silver salt solution; Preparing a colloidal solution by adding a reducing agent to the silver salt solution to which the dispersant is added; Stirring the colloidal solution at a temperature of 25 to 100 ° C. and a pressure of 10 to 250 Psi in a high pressure reactor; And it provides a method for producing a particle size controlled nano silver comprising the step of drying with a lyophilizer.

In another aspect, the present invention provides a method for producing nano-silver having a controlled particle size, characterized in that the concentration of the silver nitrate solution is 0.01 to 10 mol / L.

In another aspect, the present invention provides a method for producing nano-silver having a particle size controlled in the amount of the inorganic dispersant Laponite RDS is added in a molar ratio of silver nitrate and inorganic dispersant 1: 1 to 1: 3.

In another aspect, the present invention provides a method for producing nano-silver having a controlled particle size by adding sodium borohydride or hydrazine as the reducing agent.

In another aspect, the present invention provides a method for producing nano-silver having a controlled particle size in which the amount of the reducing agent is added in a molar ratio of silver nitrate and reducing agent in a ratio of 1: 2 to 1:10.

The method of preparing nanosilver according to the present invention has an effect of reducing the manufacturing cost by not using a separate buffer solution.

In addition, in the present invention, the nano silver has an effect of preventing the aggregation or precipitation of the nano silver particles in the colloidal solution when the particles are evenly dispersed to produce nano silver stably.

In addition, it is possible to control the size of the nano silver particles by controlling the temperature and pressure in the high-pressure reactor in the production of the nano silver according to the present invention has the effect of producing a nano silver of the desired size.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation to or in the numerical value of the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

The present invention is a nano-silver of the particle size is controlled as a manufacturing method comprising the steps of dissolving a silver nitrate solution in water to form a silver salt aqueous solution; Adding an inorganic dispersant laponite RDS to the silver salt solution; Preparing a colloidal solution by adding a reducing agent to the silver salt solution to which the dispersant is added; Stirring the colloidal solution at a temperature of 25 to 100 ° C. and a pressure of 10 to 250 Psi in a high pressure reactor; And drying with a lyophilizer.

Silver nitrate is used as a non-limiting example in the step of making the silver salt aqueous solution. The concentration of the silver nitrate solution used is preferably 0.01 to 10 mol / L. When the silver nitrate solution is used at a concentration within the above range, the silver particles are suitably present, and when the dispersing agent and the reducing agent of the next step are added, the silver particles are not dispersed and are evenly dispersed.

As the dispersant used in the present invention, among the inorganic dispersants, laponite RDS is preferably used. The inorganic dispersant Laponite RDS (Laponite RDS) has a feature that can maintain the dispersion more than a certain time more stable than other dispersants. After the dispersant is added, the solution is stirred until the solution becomes transparent. The amount of the inorganic dispersant Laponite RDS is added in a molar ratio of silver nitrate and an inorganic dispersant of 1: 1 to 1: 3. When the dispersant is added within the above range, it is possible to prevent the aggregation or precipitation of the silver particles to form a colloidal solution in which the particles are evenly dispersed, and maintain the desired pH range of the colloidal solution.

In the step of preparing a colloidal solution by adding a reducing agent to the silver salt solution to which the dispersant is added, a reducing agent is added during the stirring process, and sodium borohydride or hydrazine is preferable as the reducing agent. The amount of the reducing agent is added is the ratio of the silver nitrate and the reducing agent is added in a molar ratio of 1: 2 to 1:10, it is possible to maintain the desired pH range of the colloidal solution when the reducing agent is added within the above range.

1 is a view showing the appearance of nano-silver colloid dispersed in Laponite RDS (dispersant) in the colloidal solution state. After sodium borohydride is added as the inorganic dispersant Laponite RDS and the reducing agent, the nano silver is inserted into the dispersant Laponite RDS to prevent the nano silver particles from agglomerating with each other.

Meanwhile, in the present invention, pH is important for stability of the colloidal solution and particle size stabilization of nanosilver, and the pH is preferably 8 to 10.5. Conventional methods for controlling pH used a buffer solution, the present invention is characterized in that the pH is adjusted by changing the molar concentration ratio of the dispersing agent or reducing agent added without separately adding a buffer.

In the step of agitating the colloidal solution at a temperature of 25 to 100 ° C. and a pressure of 10 to 250 Psi in a high pressure reactor, the prepared colloidal solution is stirred until it becomes a transparent solution in a high pressure reactor to stabilize dispersion of silver particles. To achieve this. At this time, the control of the pressure as well as the temperature in the high-pressure reactor is an important factor, by controlling the temperature and pressure in the high-pressure half it can be produced nano-silver with controlled particle size. That is, nano silver particles in a desired range can be obtained. It is preferable to set it as 25-100 degreeC as said temperature of the said high pressure reactor, and it is preferable to set it as 10-250 Psi as said pressure. For example, when the nanosilver particles are manufactured by using a high pressure reactor, the size of the particles may be 300 nm or more. This size control can be seen through the embodiments described below.

Nano silver colloid can be prepared by drying the nano silver colloid after the stirring step through the high pressure reactor as described above.

The nano silver powder prepared by the present invention can control the size of the nano silver by controlling the temperature and pressure using a high pressure reactor in the stabilization step after reduction, thereby producing nano silver of a desired size.

Hereinafter, the Example and comparative example of this invention are demonstrated in detail.

Experimental Example 1 pH Concentration Change According to the Ratio of Silver Nitrate and Dispersant

After dissolving silver nitrate in water, an inorganic dispersant was added to the aqueous solution of silver nitrate at a molar ratio of 1: 1, 1: 2, and 1: 3, respectively, in preparation for the molar ratio of silver nitrate, and the reducing agent was added at a ratio of 1: 2 to silver nitrate at 25 ° C. After stabilization at, the pH change of colloidal solution was investigated. The results are shown in Table 1 below.

Silver Nitrate: Dispersant pH 1: 1 8.5 1: 2 9.3 1: 3 10.2

Experimental Example 2-pH Concentration Change According to Molar Ratio of Silver Nitrate and Reducing Agent

After dissolving silver nitrate in water, the inorganic dispersant Laponite RDS was added to the aqueous solution of silver nitrate in a 1: 3 molar ratio, and the reducing agent was compared with silver nitrate in 1: 2, 1: 3, 1: 4, 1: 5 , And stabilized at 25 ℃ with a molar ratio of 1:10, and investigated the change in pH of the colloidal solution, the results are shown in Table 2 below.

Silver Nitrate: Reducing Agent pH 1: 2 8.5 1: 3 8.8 1: 4 9.3 1: 5 9.7 1:10 10.5

Experimental Example 1 and 2 by adjusting the molar ratio of the inorganic dispersant Laponite RDS (additives) and reducing agent additives without using a buffer to adjust the pH to adjust the pH range from 8 to 10.5 to colloid It can be seen that the solution can be stabilized. In addition, it can be seen that the pH can be in the range of 8 to 10.5 by adjusting the ratio of the dispersant and the reducing agent in the above experiment.

Example 1

The silver nitrate solution was dissolved in water at a concentration of 5 mol / L, and the inorganic dispersant Laponite RDS was added in a 1: 1 molar ratio, that is, 5 mol / L, and stirred until it became transparent, followed by sodium as a reducing agent. 10 mol / L of borohydride 1: 2 ratio was added, and it stirred for 5 minutes. After this, the mixture was stirred for about 2 hours in a high pressure reactor. At this time, the temperature of the high-pressure reactor was 25 ℃, the pressure was 14.7 Psi of atmospheric pressure and stirred for a sufficient time, and then dried through a lyophilizer to prepare nano silver and observed the particles.

Example 2

In the same manner as in Example 1, but the temperature of the high-pressure reactor was 45 ℃, the pressure was set to 50 Psi of atmospheric pressure nano silver was prepared.

Example 3

In the same manner as in Example 1, but the temperature of the high-pressure reactor was 60 ℃, the pressure was set to 100 Psi of atmospheric pressure nano silver was prepared.

Example 4

In the same manner as in Example 1, but the temperature of the high-pressure reactor was 75 ℃, the pressure was set to 150 Psi of atmospheric pressure nano silver was prepared.

Example 5

In the same manner as in Example 1, but the temperature of the high-pressure reactor was 90 ℃, the pressure was set to 200 Psi of atmospheric pressure to prepare nano silver.

Example 6

In the same manner as in Example 1, but the temperature of the high-pressure reactor was 100 ℃, the pressure was set to 250 Psi of atmospheric pressure to prepare nano silver.

Comparative Example 1

In the same manner as in Example 1, an inorganic dispersant Laponite RDS was added in a 1: 0.5 molar ratio, that is, 2.5 mol / L, and sodium borohydride in a reducing agent was 5 mol / L in a 1: 1 ratio. At this time, the pH was 7.4 to thereby produce nanosilver.

Comparative Example 2

In the same manner as in Example 1, the inorganic dispersant Laponite RDS was added in a 1: 4 molar ratio, that is, 20 mol / L, and sodium borohydride in a reducing agent was 55 mol / L in a 1:11 ratio. At this time, the pH was 10.8 to thereby produce nanosilver.

Results for the Example and Comparative Example are shown in Table 3 below.

division Temperature (℃) Pressure (Psi) Nanoparticle size (nm) Example 1 25 14.7 5-20 Example 2 45 50 20-50 Example 3 60 100 50-100 Example 4 75 150 100-200 Example 5 90 200 200-300 Example 6 100 250 300- Comparative Example 1 25 14.7 50-400 Comparative Example 2 25 14.7 50-400

※ Experiment result

As a result, when the inorganic dispersant Laponite RDS and the reducing agent are added in a certain amount, it can be confirmed that nano silver particles are uniformly produced under the control of temperature and pressure. However, in the comparative example, when the amount of the dispersant and the reducing agent was added in small or large amounts, the colloidal solution was not stabilized due to low or high pH, and the particles were rarely spherical. .

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is a view showing the appearance of nano-silver colloid dispersed in Laponite RDS (dispersant) in the colloidal solution state.

2 is a TEM photograph showing nanosilver particles prepared by using a high pressure reactor at a temperature of 45 ° C. and a pressure of 50 Psi according to one embodiment of the present invention.

3 is a TEM photograph showing nanosilver particles prepared by using a high pressure reactor at a temperature of 60 ° C. and a pressure of 100 Psi according to one embodiment of the present invention.

Claims (10)

The particle size of the nano silver colloidal solution prepared by dissolving the silver nitrate solution in water and adding the inorganic dispersant Laponite RDS and the reducing agent was dried in a high pressure reactor by stirring at a temperature of 25 to 100 ° C. and a pressure of 10 to 250 Psi. Controlled nano silver. The method of claim 1, The silver nanoparticles of controlled particle size, characterized in that the concentration of the silver nitrate solution is 0.01 to 10 mol / L. The method of claim 1, The amount of the inorganic dispersant Laponite RDS is added to the nano silver having a controlled particle size in which the ratio of silver nitrate and inorganic dispersant is added in a molar ratio of 1: 1 to 1: 3. The method of claim 1, The reducing agent is nano silver having a particle size controlled by adding sodium borohydride or hydrazine. The method of claim 4, wherein The amount of the reducing agent added is nano silver having a controlled particle size in which the ratio of the silver nitrate and the reducing agent is added in a molar ratio of 1: 2 to 1:10. In preparing nano silver particles, Dissolving the silver nitrate solution in water to form an aqueous silver salt solution; Adding an inorganic dispersant laponite RDS to the silver salt solution; Preparing a colloidal solution by adding a reducing agent to the silver salt solution to which the dispersant is added; Stirring the colloidal solution at a temperature of 25 to 100 ° C. and a pressure of 10 to 250 Psi in a high pressure reactor; And Particle size controlled nano silver manufacturing method comprising the step of drying with a lyophilizer. The method of claim 6, The method for producing nano-silver having a controlled particle size, characterized in that the concentration of the silver nitrate solution is 0.01 to 10 mol / L. The method of claim 6, The amount of the inorganic dispersant Laponite RDS (Laponite RDS) is added in the ratio of the silver nitrate and the inorganic dispersant is a method of producing a nano silver having a controlled particle size is added in a molar ratio of 1: 1 to 1: 3. The method of claim 6, The reducing agent is a method for producing nano-silver having a particle size controlled by adding sodium borohydride or hydrazine. 10. The method of claim 9, The amount of the reducing agent is added is the manufacturing method of the nano-silver of the particle size controlled silver nitrate and the reducing agent is added in a molar ratio of 1: 2 to 1:10.

Images