KR100763036B1 - A method for preparation of silver nano colloid controlling particle size - Google Patents

Abstract

A method for manufacturing nano-silver colloids is provided to improve heat transfer efficiency or electric conductivity, by uniformly dispersing nano-silver colloids in a heat transfer medium or electron ink. Ammonia water is added into silver nitrate aqueous solution. Surfactant is added into the solution where the ammonia water is added. Polyhydric alcohol is added into the solution where the surfactant is added, thereby forming silver particles. The polyhydric alcohol is selected from a group consisting of glucose, ethylene glycol, glycerol, threitol, aribitol, mannitol, galacitol, sorbitol, and a mixture thereof.

Description

A method for preparation of silver nano colloid controlling particle size

FIG. 1 is a scanning electron microscope (SEM) photograph of silver nano colloid prepared without adding a co-surfactant in Example 1. FIG.

FIG. 2 shows the results of UV spectral analysis of silver nanocolloids prepared without the addition of cosurfactants in Example 1. FIG.

FIG. 3 is a scanning electron microscope (SEM) photograph of silver nano colloid prepared by adding butanol in a molar ratio of silver nitrate 1:30 as a co-surfactant in Example 2. FIG.

FIG. 4 is a scanning electron microscope (SEM) photograph of silver nano colloid prepared by adding butanol in a molar ratio of silver nitrate 1:60 as a co-surfactant in Example 3. FIG.

FIG. 5 is a scanning electron microscope (SEM) photograph of silver nano colloid prepared by adding butanol in a molar ratio of silver 90: 1 as a co-surfactant in Example 4. FIG.

FIG. 6 shows particle distribution analysis results of silver nano colloids prepared by adding butanol as a molar ratio of 1: 0, 1:30, 1:60, and 1:90 to silver nitrate as co-surfactants in Examples 1 to 4. FIG.

FIG. 7 is a scanning electron microscope (SEM) photograph of silver nano colloids prepared by adding hexanol as a molar ratio of silver nitrate 1:30 as a co-surfactant in Example 5.

FIG. 8 is a scanning electron microscope (SEM) photograph of silver nano colloid prepared by adding octanol to a molar ratio of silver nitrate 1:30 as a co-surfactant in Example 6. FIG.

The present invention relates to a method for preparing silver nanocolloids having easy particle size control, and more particularly, adding ammonia water to an aqueous solution of silver nitrate, adding a surfactant to a solution containing ammonia water, and the surfactant It relates to a nano-colloid manufacturing method comprising the step of forming a silver particle by adding polyhydric alcohol to the added solution.

Silver nanoparticles have good antibacterial and bactericidal effects, and are widely used in industrial fields because they have excellent thermal and electrical conductivity. In particular, by incorporating a heat transfer medium to improve heat transfer efficiency, or by using a conductive nano-ink using silver nano colloids can be printed circuit boards using inkjet printers, such as paper, vinyl instead of conventional printed circuit boards. As an example, a radio frequency identification (RFID) antenna can be printed on the product packaging. The circuit is printed using silver nanocolloid ink, which can replace the existing antenna. In addition to RFID, it can be used as a wireless recognition antenna for traffic cards, and can be widely used in the electronics industry such as electromagnetic shielding and various display devices. In general, silver nano colloids having a particle size of about 5 nm are suitable for incorporation into a heat transfer medium to increase thermal efficiency, and silver nano colloids used for electronic ink are known to have a suitable particle size of about 10-50 nm.

The manufacturing method of silver nanoparticles can be divided into a manufacturing method using a gas phase, a manufacturing method using a liquid phase, a mechanical manufacturing method and a manufacturing method using electromagnetic waves. Gas phase evaporation condensation and gaseous reduction method are used for the gas phase production method, and chemical reduction method and spray drying method are used for the liquid phase method and mechanical grinding method using mechanical force. As a manufacturing method using electromagnetic waves, there is a manufacturing method using gamma rays or plasma. In general, the manufacturing method using the liquid phase has the advantage that the powder can be produced at a low cost of the device. However, the manufacturing method using the liquid phase has a disadvantage in that the aggregation of individual particles is strong, so that the particle shape is not uniform, the dispersibility is lowered, or the particle size is difficult to control.

An object of the present invention is to prepare a silver nano colloid in a liquid phase by using a chemical reduction method, by dispersing uniformly in the medium used, such as a heat transfer medium or electronic ink to improve heat transfer efficiency or electrical conductivity It is to provide a manufacturing method for producing an excellent silver nano colloid.

In addition, another object of the present invention to provide a method for producing a silver nano colloid that can easily control the size of the silver nanoparticles to control the particle size according to the intended use.

The present inventors can produce silver nanocolloids having a uniform particle size distribution by preparing a silver nanocolloid by adding a polyhydric alcohol as a reducing agent to a silver solution containing a surfactant in a method of producing silver colloid by a chemical reduction method in a liquid phase. In particular, by further using a co-surfactant in the step of adding the surfactant to develop a silver nano-colloid manufacturing method that can easily control the size of the particles according to the amount of the co-surfactant to complete the present invention Reached.

The present invention relates to a method for preparing a silver nano colloid with easy particle size control, and more particularly, adding ammonia water to an aqueous solution of silver nitrate, adding a surfactant to a solution to which ammonia water is added, and the surfactant It relates to a nano-colloid manufacturing method comprising the step of forming a silver particle by adding polyhydric alcohol to the added solution.

More preferably, the cosurfactant is added to make it easier to control the particle size in the surfactant addition step to easily increase the size of the silver nanoparticles to a size of several to several hundred nm, more preferably several to several tens of nm. It provides a controllable silver nano colloid manufacturing method.

In addition, the silver nano colloidal particles produced by the production method according to the present invention has a uniform distribution in size and is characterized in that the particles are uniformly dispersed without agglomeration, in combination with a surfactant, a polyhydric alcohol and a cosurfactant. The size can be adjusted in the range of several hundreds to several hundred nm, and more preferably, the size can be controlled in several tens to several tens nm suitable for use in a heat transfer medium mixed material or an electronic ink.

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

Silver nano-colloid manufacturing method of the present invention is characterized by comprising the following steps.

Adding aqueous ammonia to the silver aqueous solution;

Adding a surfactant to the solution to which ammonia water is added; And

Adding polyhydric alcohol to the solution to which the surfactant is added to form silver particles.

The production method of preparing an aqueous solution of silver nitrate, adding ammonia water to the solution, preparing a transparent solution of silver ammonia nitrate, and then adding a reducing organic compound such as formaldehyde as a reducing agent is widely known as a silver mirror reaction. In the conventional silver mirror reaction, a thin silver thin film is formed.

The production method of the present invention for producing a silver colloid is to form a reduced silver particles using a reducing agent that serves to reduce the silver ions, such as the silver mirror reaction, the silver ions do not aggregate into a thin film to form nanoparticles In order to ensure that the surfactant is added to the aqueous solution of silver ammonia, more preferably co-surfactant which serves to control the particle size in the process of forming nanoparticles.

In general, sodium borohydride and hydrazine are known as reducing agents. However, these reducing agents have a good reducing power, but are expensive and thus have disadvantages in production cost. In addition, since the reducing power is high, it is difficult to uniformly control the size distribution of the particles, and it is difficult to control the size by a method of changing the type of surfactant or the type or content of the cosurfactant. Accordingly, in the present invention, the particle size distribution according to the type of surfactant, the type and content of the co-surfactant can be easily adjusted by inexpensive, eco-friendly, easy to handle, low reducing power, but mild reduction reaction compared to the conventional reducing agent. The above effects were obtained by using a polyhydric alcohol which can be used as a reducing agent. In the case of using monohydric alcohols such as ethanol instead of polyhydric alcohols as the reducing agent, the reducing power is so weak that the reaction time is long, which is not suitable for the production of silver nano colloids, and the effect of controlling the desired particle size in the present invention was not obtained.

The polyhydric alcohol used as the reducing agent in the present invention does not need to be limited to the type, glucose (Glucose), ethylene glycol (Ethylene glycol), glycerol (Glycerol), Thritol (Atriitol), aryitol (Arabitol), mannitol (Mannitol), galactitol, sorbitol (Sorbitol) or mixtures thereof can be used, and glucose as a reducing agent can form silver particles of several to several tens of nm with appropriate reducing power and according to the content of the cosurfactant It is more preferable to control the size, but is not limited thereto.

The polyhydric alcohol may be added in a molar ratio of 0.1 to 100 with respect to silver nitrate, and preferably added in a content of 1 to 50 molar ratios. Since polyhydric alcohol acts as a reducing agent, it shows a proper reducing power only at a molar ratio of 1 to silver nitrate. If the amount of polyhydric alcohol is more than 100 molar ratio or less than 0.1 molar ratio with respect to silver nitrate, there is a problem in that the silver nano colloid is not properly manufactured. That is, when the content of polyhydric alcohol is too small, it is difficult to form silver particles properly due to low reducing power, and when it exceeds 100 molar ratio, silver nano colloids are not properly manufactured and large lumps are formed.

In the present invention, when silver ions in the aqueous solution of silver nitrate added with ammonia are reacted with a reducing agent to form silver nanoparticles, the resulting particles are agglomerated with one another, resulting in large particle sizes and uneven particle size distribution. Surfactants were used to prevent silver and to produce silver nanoparticles with a uniform particle size distribution. Surfactants that can be used include cationic surfactants, anionic surfactants, nonionic surfactants and the like.

In the present invention, the material that can be used as a surfactant is cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, sodium dodecyl sulfate, steric acid, methyl Glucoside (Methyl glucoside), Octyl glucoside, Polyoxyethylene sorbitan monolaurate, Polyoxyethylene sorbitan monopalmitate, Polyoxyethylene sorbitan monostea Polyoxyethylene sorbitan monostearate, Polyoxyethylene sorbitan monooleate, Sorbitan monolaurate, Ethylene glycol monolaurate, Propylene glycol monolaurate glycol monolaurate), triglycerol monola Triglycerol monostearate or a mixture thereof. Cetyltrimethylammonium bromide or cetyltrimethylammonium chloride is more preferable because it is easy to control the size of the silver particles to a size of several tens to several tens of nm, but not necessarily It is not limited.

The surfactant may be added in an amount of 0.1 to 100 molar ratio with respect to silver nitrate, and more preferably in an amount of 1 to 50 molar ratio. If less than 0.1 molar ratio, it is difficult to produce silver particles having a uniform size distribution due to agglomeration of silver particles, and when used in excess of 100 molar ratios, the production time of silver particles may be too long, resulting in no productivity. However, it is not economical because it is not meaningful by the addition.

In the present invention, when preparing a silver nano colloid, micelles are generated by a surfactant in an aqueous reaction solution, and when the hydrocarbon chain alcohol is added thereto, the size of the micelles is changed. This change in the size of the micelle changes the size of the silver nano colloidal particles produced. That is, the hydrocarbon chain alcohol can easily control the size of the silver particles formed by acting as a co-surfactant, and the size of the silver nanoparticles can be adjusted according to the type and concentration of the hydrocarbon alcohol added.

The material that can be used as the co-surfactant is an alcohol compound having an alkyl group of C ₄ ~ C ₁₈ , for example, butanol, pentanol, hexanol, heptanol, octanol, octanol ), Nonanol, decyl alcohol, undecanol, octadecanol, and the like. In the case of using butanol as the co-surfactant, the effect of controlling the particle size of silver is apparent in the range of several to several tens of nm depending on the content, more preferably hexanol or octanol in terms of particle shape or size distribution. Do.

The co-surfactant may be further added to the step of adding a surfactant to control the size of the particles, it is an advantage that the size of the particles can be more easily adjusted when added. When adding a co-surfactant, it is preferable that the addition amount is added in 0.1-200 molar ratio content with respect to silver nitrate, and it is more preferable to use 1-200 molar ratio. If the co-surfactant is added in less than 0.1 molar ratio with respect to silver nitrate, the function of controlling the particle size is insignificant. If the co-surfactant exceeds 200 molar ratio, particles are not formed in nano size and silver is precipitated in thin film or lump form. May occur.

In the production method according to the present invention, it is preferable to use ultrapure water from which oxygen is removed as the water used for preparing the silver nitrate solution. In addition, it is preferable to continuously flow an inert gas such as nitrogen into the reaction solution so that oxygen is not dissolved. When oxygen is present in the reaction system, silver nanoparticles are formed and oxidized to form a silver oxide, so it is preferable to use a reaction system that suppresses dissolved oxygen.

In addition, in the step of forming the silver particles by adding a reducing agent, it is not necessary to limit the reaction temperature, but it is preferable to maintain 70 to 100 degrees to facilitate the reduction reaction.

As shown in FIGS. 1, 3, 4, 5, 7 and 8, the silver nano colloidal particles produced by the manufacturing method according to the present invention have uniform particle sizes, and the particles are not aggregated and uniform. It can be confirmed that the dispersion, and as can be seen in the particle size analysis results of FIG. 6, the average particle diameter can be changed according to the addition of the co-surfactant, and the particle size distribution has an excellent uniformity while the average particle diameter is increased. Can be.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only for illustrating the present invention, and the content of the present invention is not limited by the following Examples.

To cosurfactants  According Silver nano  Colloidal synthesis

Example 1 In the absence of a cosurfactant

Replace the 100 ml flask with nitrogen for 5 minutes. Put a Stirring Bar into the flask. 0.05 g of silver nitrate (AgNO ₃ ) and 60 ml of distilled water are administered to the flask, and 0.05 ml (28 wt%) of ammonia water is added while stirring, followed by stirring for 10 minutes. To this clear solution, 2.04 ml (28 wt%) of Cetyltrimethylammonium chloride is added (molar ratio of silver nitrate 1: 6) and stirred for 30 minutes. 0.424 g of glucose is added (molar ratio 1: 8 relative to silver nitrate), and the reaction temperature is raised to 90 to 100 ° C. in 30 minutes. Nitrogen is allowed to flow continuously in a small amount and allowed to react for 36 hours. After the reaction is completed, the reaction mixture is cooled to room temperature and a product is obtained. The ultrapure water used in the synthesis process uses ultrapure water deoxygenated. Scanning electron microscopy (SEM) analysis of the prepared silver nanocolloids was performed by Sirion of FEI, the Netherlands. The results are the same as in FIG. It is the same as the first distribution at and the average particle size is 6.3 nm. The UV-Visible Spectrophotometer was analyzed by UV-1700 of Shimadzu Co., Ltd. in Japan, and the result of the UV spectrum analysis showed a silver nano-specific peak at a wavelength of 420 nm as shown in FIG. 2.

<Examples 2 to 4> Butanol as a cosurfactant

Silver nano colloids were prepared under the same conditions as in Example 1, except that normal butanol was added in the content (30, 60, 90 molar ratio) of Table 1 when cetyltrimethylammonium chloride was added as a surfactant.

The SEM photograph of the silver nanocolloid prepared in Example 2 is shown in FIG. 3, the SEM photograph of the silver nanocolloid of Example 3 is shown in FIG. 4, and the SEM photograph of the silver nano colloid prepared by Example 4 is shown in FIG. 5. Particle size distribution for silver colloids of Examples 1 to 4 is shown in FIG. 6.

<Comparative Example 1> Excessive addition of cosurfactant

Silver nano colloids were prepared under the same conditions as in Example 1, except that normal butanol was added in an amount of 240 mole ratio with respect to silver nitrate when cetyltrimethylammonium chloride was added as a surfactant.

TABLE 1

Referring to Table 1 and the results of FIGS. 1 and 3 to 5, the silver colloid manufactured without using the co-surfactant in Example 1 had an average particle diameter of 6.3 nm, but the silver produced as the butanol content was increased. It can be seen that the average particle diameter of the particles is increased and uniformly dispersed without forming the aggregation phenomenon between the particles. In addition, referring to Figure 6 it can be seen that the average particle diameter is increased while maintaining a uniform particle size distribution even if the addition amount of butanol increases.

On the other hand, in the case of using an excess butanol as in Comparative Example 1, silver was not formed as a nano-sized particle, but silver was precipitated as a thin film or a large particle mass, which was not preferable.

Example 5 When Hexanol was Used as Cosurfactant

Co-surfactant was added in an amount of 30 molar ratio to silver nitrate in the same manner as in Example 2 except that n-hexanol was used instead of n-butanol as a co-surfactant, thereby preparing silver nanocolloids. Prepared. Scanning electron microscope (SEM) analysis results of the prepared silver nano colloid were as shown in FIG. 7, and the average particle size was 6.6 nm.

Example 6 Octanol as Cosurfactant

Co-surfactant was added in an amount of 30 molar ratio to silver nitrate in the same manner as in Example 2 except that n-hexanol was used instead of n-butanol as a co-surfactant, thereby preparing silver nanocolloids. Prepared. Scanning electron microscopy (SEM) analysis results of the prepared silver nano colloid are as shown in FIG. 8, and the silver nanoparticles having an average particle size of 3.7 nm were prepared.

Silver Nano Colloid Synthesis by Surfactant

Example 7 When Sodium Dodecyl Sulfate was Used as a Surfactant

Silver nanocolloids were prepared under the same conditions as in Example 3 except that sodium dodecyl sulfate was used in place of cetyltrimethylammonium chloride in the same molar ratio (6 molar ratio to silver nitrate). . As a result of the particle size analysis of the prepared silver nano colloid, silver nanoparticles having an average particle size of 10 nm were prepared.

Example 8 When Sorbent Monolaurate was Used as a Surfactant

Silver nanocolloids were prepared under the same conditions as in Example 3, except that sorbitan monolaurate was used instead of cetyltrimethylammonium chloride as the surfactant (6 mol to silver nitrate). . As a result of particle size analysis of the prepared silver nanocolloids, silver nanoparticles having an average particle size of 132 nm were prepared.

Example 9 When Polyoxyethylene Sorbent Monolaurate was Used as a Surfactant

Silver nanoparticles were prepared under the same conditions as in Example 3, except that polyoxyethylene sorbitan monolaurate was used instead of cetyltrimethylammonium chloride as the surfactant (6 mol to silver nitrate). Colloids were prepared. As a result of the particle size analysis of the prepared silver nanocolloids, silver nanoparticles having an average particle size of 211 nm were prepared.

Silver Nano Colloid Synthesis by Reducing Agent

Example 10 When Mannitol was Used as a Reducing Agent

Silver nanocolloids were prepared under the same conditions as in Example 3 except for using the same molar ratio (8 molar ratio to silver nitrate) instead of glucose as a reducing agent. As a result of the particle size analysis of the prepared silver nano colloid, silver nanoparticles having an average particle size of 12.9 nm were prepared.

Example 11 When Sorbitol is Used as a Reducing Agent

Silver nanocolloids were prepared under the same conditions as in Example 3, except that sorbitol (Sorbitol) was used instead of glucose as the reducing agent (eight molar ratios to silver nitrate). As a result of the particle size analysis of the prepared silver nano colloid, silver nanoparticles having an average particle size of 17.1 nm were prepared.

As described above, according to the present invention, a silver nanocolloid having a uniform distribution could be prepared using polyhydric alcohol as a reducing agent, and particle size could be adjusted according to the type of surfactant and reducing agent, in particular cosurfactant. There is an effect that can control the silver nano colloidal particle size while maintaining a uniform particle size distribution according to the addition amount, it is possible to easily produce silver nano colloidal particles of various uses according to the size of the particle, in particular heat transfer media or electronic ink There is an advantage that it is easy to produce a silver nano-colloid whose particle size is controlled in the range of several to several tens nm suitable for the application.

Claims (8)

Adding aqueous ammonia to the silver aqueous solution; Adding a surfactant to the solution to which ammonia water is added; And Adding polyhydric alcohol to the solution to which the surfactant is added to form silver particles; Method for producing a silver nano-colloids easy to control the particle size comprising a. The method of claim 1, The polyhydric alcohol is selected from the group consisting of glucose, ethylene glycol, glycerol, pentitol, aviitol, mannitol, galactitol, sorbitol and mixtures thereof. The method of claim 2, The amount of polyhydric alcohol added is 0.1 to 100 molar ratio with respect to silver nitrate manufacturing method of the silver nano-colloid. The method of claim 1, The surfactant may be cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, sodium dodecyl sulfate, steric acid, methyl glucoside, octylglucoside, polyoxyethylene sorbitan bonolaurate, polyoxyethylene sorbitan monopalmitate, Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, sorbitan monolaurate, ethylene glycol monolaurate, propylene glycol monolaurate, triglycerol monolaurate and mixtures thereof Method for producing a silver nano colloid, characterized in that selected. The method of claim 4, wherein The addition amount of the surfactant is a method for producing silver nano colloids, characterized in that 0.1 to 100 molar ratio with respect to silver nitrate. The method of claim 1, In the step of adding the surfactant further added co-surfactant selected from the group consisting of butanol, pentanol, hexanol, heptanol, octanol, nonanol, decyl alcohol, undecanol, octadecanol and mixtures thereof Method for producing a silver nano colloid, characterized in that. The method of claim 6, The amount of the co-surfactant added is 0.1 to 200 molar ratio with respect to silver nitrate manufacturing method of the silver nano-colloid. The method of claim 6, The surfactant is 1-50 molar ratio of cetyltrimethylammonium bromide or cetyltrimethylammonium chloride with respect to silver nitrate, the polyhydric alcohol is 1-50 molar ratio of glucose with respect to silver nitrate, and the cosurfactant is butanol, pentanol, hetanol or A method for producing silver nanocolloids, characterized in that at least one selected from octanol is used at a molar ratio of 1 to 200 with respect to silver nitrate.

Images