KR101659449B1 - Preparation method for silver colloid - Google Patents

Abstract

The present invention relates to a method for producing silver colloid, and more particularly, to a method for producing silver colloid of the present invention, comprising the steps of: preparing a mixed solution by dissolving silver salt in an organic solvent; And dissolving the vinyl polymer in the mixed solution to prepare a silver colloid. In the step of preparing the silver colloid, nano-sized silver colloid particles are formed without adding a reducing agent and a stabilizer .

Description

PREPARATION METHOD FOR SILVER COLLOID < RTI ID = 0.0 >

The present invention relates to a method of preparing silver colloid, and more particularly, it does not require any additive such as a stabilizer, a dispersant, and a complexing agent, and a high purity of nanoparticle size can produce colloidal particles, Which is applicable to various industrial fields such as conductive adhesives, electromagnetic wave shielding agents, paints, enhancers for surface enhanced Raman scattering, ink additives, antibacterial agents, antibiotics, and the like.

Metal particles such as nano-sized copper (Cu), zinc (Zn), platinum (Pt), and silver (Ag) have been widely used as antibacterial agents for a long time. Among them, colloidal silver has been widely used as antibacterial and antiviral materials because of its low cost and relatively low human toxicity. In particular, silver nanoparticles of 1 to 100 nm in size are known to be very useful for the destruction of bacteria or viruses because they readily penetrate into cells and inhibit the metabolic process. The active research on colloidal silver particles is closely related to the discovery of surface plasmonic resonance (SPR) phenomenon.

Plasmon resonance is a phenomenon in which incident electromagnetic waves are absorbed as electromagnetic waves having an externally incident electromagnetic wave and a negative dielectric surface function of metal surface free electrons coincide with each other. Electromagnetic wave absorption causes surface electrons present at the metal and dielectric interfaces to vibrate collectively, generating surface plasmonic waves traveling along the interface from the excited electrons. This phenomenon is mainly observed in a metal having a negative dielectric constant and easy to emit electrons by external stimuli such as gold, silver, copper, and aluminum.

The silver colloid in which the silver particles in the metallic state are uniformly dispersed can be prepared by chemical reduction. Basically, silver salts (precursors) to be reduced, reducing agents capable of reducing silver ions to metals, A stabilizer for inhibiting the growth and aggregation of silver particles of a size or an organic solvent in which a surfactant and silver are dispersed.

The following Table 1 shows the constituents mainly used in the chemical reduction method.

Constituent compound Silver salt _{AgNO 3, AgSO 4, CH 3} COOAg, AgCl reducing agent NaBH ₄ , hydrazine, hydrazine salt, HCHO, citrate, ascorbic acid, H ₂ O ₂ , glucose Surfactants and stabilizers oleic acid, polyvinyl pyrrolidone, poly (amido amine), dodecanthiol, polyaniline, lignosulfonate, CTAB, triphenylphosphine Dispersive medium H ₂ O, DMA, DMF, DEG, EG, ethanol, acetone, methanol, NMP pH control HCl, KOH, NaOH

As shown in Table 1, various chemical compounds such as silver salts, reducing agents, surfactant, dispersion medium, and pH control are required in the chemical reduction method. Despite the relatively simple preparation method, the pH generated during unreacted silver salt and silver ion reduction change, requires the use of powerful reducing agents such as hydrazine _{(hydrazine), HCHO, NaBH 4} . However, these additives have caused problems such as explosive reduction reaction, hydroxide formation and coagulation from metal silver due to pH control, inactivation and purification of metal surface due to excessive concentration of surfactants and stabilizers.

Recently, pyrrole, aniline, chitosan, soluble starch, poly (arylene ether), which act as a surfactant or stabilizer for particle growth inhibition and dispersion stability, Methods for producing silver colloids by compounds such as polypeptides, heparin, hyaluronan, sodium alginate, lignosulfonate, and polyamidoamine were reported in turn .

Korean Patent Laid-Open Publication No. 2003-75231 discloses a silver colloid produced by such a chemical reduction method. The silver colloid is prepared by dissolving silver particles in an aqueous nitric acid solution to prepare a silver ion aqueous solution. And a step of adding a reducing agent and a surfactant to the solution, wherein a high concentration of silver colloid capable of controlling the particle size and the particle distribution is disclosed.

In Korean Patent No. 477,912, silver nitrate aqueous solution and an alkaline substance are reacted with each other by mixing an aqueous solution of nitric acid and a silver lump to form a silver precipitate. The silver precipitate is filtered and dried, dispersed in water, And then adding a reducing agent to form a silver colloid.

Korean Patent Publication No. 2005-40226 discloses a chelating dispersant comprising a copolymer of an acrylic acid derivative and maleic anhydride, a water-soluble alcohol and a reducing agent selected from thioglycol, thioglycolic acid and thiourea. An electroless plating solution of a noble metal is disclosed.

Japanese Patent No. 4,872,083 discloses a method for producing a metal colloid utilizing microwave irradiation and the reducing power of the dispersion medium itself without using a dispersant. In this way, the production of relatively inexpensive silver colloids has been attempted through the use of excessive amounts of compounds and shortening of process steps.

However, the above-mentioned preparation methods are difficult to obtain a uniform particle shape due to butterfly shape and agglomeration, and it is necessary to control the pH and to form a complex compound even though a compound acting as a reducing agent and a stabilizer together with microwave irradiation is used. There is a problem that a strongly acidic solvent such as methanesulfonic acid or ammonium peroxysulfate and a polymerization initiator are required for the purpose of reducing agent and stabilizer.

KR 2003-75231 A KR 10-477912 B1 KR 2005-40226 A JP 10-4872083 B2

 Droddowicz-Tomsia, Krystyna, Goldys, Ewa. M., Gold and Silver Nanowires for Fluorescence Enhancement, Nanowires - Fundamental Research, Abbass Hashim (Ed.), 2011, ISBN: 978-953-307-327-9, 309-313  Kim, Dong-Ha, Application of surface plasmon resonance, Polymer Science and Technology, Vol. 19, No. 4, 2008, 318-324  Daghestani, H. N., Day, B. N., Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors, Sensors, 10, 9630-9646, 2010  Milczarek, G., Rebis, T., Fabianska, J., One-step synthesis of lignosulfonate-stabilized silver nanoparticles, Colloids and Surface B: Biointerfaces, 105, 335-341, 2013  Bober, P., Stejskal, J., Prokes, T.J., In-Situ prepared polyaniline-silver composites: Singla and Two-step strategies, 122, 259-266, 2014  Conservative inks: Polypyrrole, Pseudomonas spp., Pseudomonas spp., Pseudomonas spp., Pseudomonas spp. -silver colloids, Electrochimica Acta, 122, 296-302. 2014  Zhao, M., Xia, Y., Li, Q., Ma, X., Quan, F., Geng, C., Han, Z., Microwave-assisted synthesis of silver nanoparticles using sodium alginate and their antibacterial activity, Colloids and Surfaces A: Physicochemical Engineering Aspects, 444, 180-188, 2014  Al-Thabaiti, SA, El-Mossalamy, EH, Starch-directed Green Synthesis, Characterization and Morphology of Silver Nanoparticles, Colloids Surface B: Biointerfaces, 102 , 578-584, 2013  Baset, S., Akbari, H., Zeynali, H., Shafie, M., Size Measurement of Metal and Semiconductor Nanoparticles via UV-VIS Absorption Spectra, Digest Journal of Nanomaterials and Biostructures, 6 (2), 709-716, 2011

Accordingly, the present invention has been made to solve the problems in the silver colloid production method, and as a result, it has been found that by applying an organic solvent and a vinyl-based polymer to silver salts, a separate additive such as a stabilizer, a dispersant, a polymerization initiator, It is possible to reduce the number of processing steps and to form uniform nano-sized silver colloid particles, and at the same time, it is possible to manufacture silver colloids of high purity by preventing the incorporation of unnecessary foreign substances, thereby completing the invention.

It is an object of the present invention to provide a method for producing high-purity silver colloid by preventing the incorporation of unnecessary foreign matter without adding a reducing agent and a stabilizer.

The method for producing silver colloid of the present invention comprises the steps of: preparing a mixed solution by dissolving silver salt in an organic solvent; And dissolving the vinyl polymer in the mixed solution to prepare a silver colloid. In the step of preparing the silver colloid, nano-sized silver colloid particles are formed without adding a reducing agent and a stabilizer .

The silver salt may be one or more selected from the group consisting of silver nitrate, silver nitrate, silver sulfate and silver iodide.

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The organic solvent may be one or more selected from the group consisting of ethanol, methanol, N-methyl-2-pyrrolidone, tetrahydrofuran, dimethylsulfoxide and N, N-dimethylacetamide.

The vinyl-based polymer may be a polyvinylformal, poly (N-vinylcarbazole), or a mixture of the two.

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Each of the above steps may be performed at a temperature of 25 to 100 ° C.

The silver colloid may have a particle size of 0.1 to 100 nm.

The silver colloid production method of the present invention does not require a separate additive such as a stabilizer, a dispersant, a polymerization initiator, and a complexing agent by adding a vinyl-based polymer, thereby reducing a process step and a processing cost, The silver colloid of high purity can be produced by preventing the incorporation.

In addition, the silver colloid of the present invention can form uniform nano-sized silver colloid particles and can be used in various industrial fields such as conductive adhesives, electromagnetic wave shielding agents, paints, enhancers for surface enhanced Raman scattering, ink additives, antibacterial agents, Can be utilized.

1 is a UV-VIS spectrum of the silver colloid solution prepared in Example 1 of the present invention.
2 is a UV-VIS spectrum of the silver colloid solution prepared in Example 2 of the present invention.
3 is a UV-VIS spectrum of the silver colloid solution prepared in Example 3 of the present invention.
4 is a UV-VIS spectrum of the silver colloid solution prepared in the comparative example of the present invention.

Hereinafter, the present invention will be described in more detail through examples and the like.

The method for producing silver colloid of the present invention comprises the steps of: preparing a mixed solution by dissolving silver salt in an organic solvent; And dissolving the vinyl polymer in the mixed solution to prepare a silver colloid. In the step of preparing the silver colloid, nano-sized silver colloid particles are formed without adding a reducing agent and a stabilizer .

The silver salt may be one or more selected from the group consisting of silver nitrate, silver nitrate, silver sulfate and silver iodide. It is preferable to use silver nitrate or silver sulfate.

When the content of the silver salt is small, the concentration of the silver colloid to be produced may be very low. On the contrary, when the silver salt is insoluble in the organic solvent in many cases, irregular silver particles can be formed and the time required for the precipitation and reduction reaction is long There may be a problem losing.

The organic solvent may be at least one selected from the group consisting of ethanol, methanol, N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), dimethyl sulfoxide , DMSO), and N, N-dimethylacetamide (DMA). The organic solvent is advantageous for forming nano-sized silver colloid particles because of its high ionization tendency and electron-rich Lewis acid properties compared to conventional organic solvents. In addition, the organic solvent has a high solubility in vinyl-based polymers and silver salts.

The vinyl-based polymer may be poly (vinyformal), PVF, poly (N-vinylcarbazole), PNVC, or a mixture of the two. The vinyl polymer may be formed by complexing and reducing silver ions by oxygen (O) and nitrogen (N) atoms originating from an acetal group and a carbazole group bonded to a vinyl group, It serves as a dispersing agent for dispersing the particles, and uniform nano-sized silver colloid particles can be formed without using any additive.

If the content of the vinyl polymer is small, it may not be dissolved in the organic solvent. On the contrary, in many cases, deposition of metal particles may occur due to rapid reduction.

Each of the above steps may be performed at a temperature of 25 to 100 ° C. In particular, when the vinyl polymer is dissolved, if the melting temperature is lower than 25 ° C, the solubility of the organic solvent with respect to the polymer may be low. On the contrary, if the vinyl polymer is higher than 100 ° C, the organic solvent used as the dispersion medium may be evaporated . And preferably at a temperature of 50 to 80 캜.

The silver colloid prepared in the present invention may have a particle size of 0.1 to 100 nm. If the particle size is less than 0.1 nm, the effect of surface plasmon is insufficient, which is not suitable for amplification using the Raman effect, or the quantum yield may be lowered. On the contrary, when the particle size is larger than 100 nm, There may be a problem that dispersion is not done properly.

The average particle diameter of the silver colloid particles was calculated by the following equation.

[Mathematical Expression]

G is the full width at half maximum (FWHM) calculated at the surface plasmonic peak, g ₀ is the velocity of bulk scattering and the value is 5 * 10 ¹² s ^-1 , A is 0.75 for silver particles, v _f is the Fermi velocity and its value is 1.39 * 10 ⁶ m / s. The half width value (FWHM) is a value calculated when a peak at which a surface plasmon occurs is approximated by a Lorentz curve.

The silver colloid of the present invention can be applied to a film having antimicrobial, bactericidal, antistatic, electromagnetic wave shielding, insoluble, photosensitive, and deodorant properties dispersed in a water-soluble polymer substrate such as water-dispersed polyurethane or water- In addition, it can be utilized in various industrial fields such as functionalized glass, metal, ceramic, surface enhanced Raman scattering spectroscopy (SERS) enhancer, ink active additive, conductive adhesive which can be used in electrical products.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

 [Example 1]

At 50 ° C, 0.1 g of silver nitrate was placed in a 25-ml glass bottle and 10 g of DMA (N, N-dimethylacetamide) was added to completely dissolve the silver nitrate. To the solution was added 0.1 g of PVF to obtain a completely dissolved solution. After 5 hours, a yellow color appeared in the solution, indicating that a silver particle with a size of 0.4 nm was generated by the reduction of the silver ion.

To observe the reduction of the silver colloid, the formation of silver particles was observed using UV-VIS spectroscopy. Nano - sized silver particles showed a peak due to surface plasmon resonance in the wavelength range of about 390 to 420 nm.

1 is a UV-VIS spectrum of the silver colloid solution obtained in Example 2. Fig. As shown in FIG. 12, a peak due to surface plasmon resonance of silver particles was observed at a wavelength of 410 nm. After 5 hours, the intensity of the surface plasmon resonance peak did not increase any longer, indicating that the silver ion reduction reaction was completed.

 [Example 2]

At 25 ° C, 0.1 g of silver nitrate was placed in a 25-ml glass bottle and 10 g of NMP was added to completely dissolve the silver nitrate. To the solution was added 0.1 g of PVF to obtain a completely dissolved solution. After one hour, the solution showed a yellow color, indicating that a silver particle size of 0.2 nm was generated by the reduction of the silver ion.

2 is a UV-VIS spectrum of the silver colloid solution obtained in Example 2. Fig. As can be seen from FIG. 2, a peak due to surface plasmon resonance of silver particles was observed at a wavelength of 400 nm. The intensity of the surface plasmon resonance peak did not increase any more after 1 hour, indicating that the silver ion reduction reaction was terminated.

[Example 3]

At 70 ° C, 0.1 g of silver nitrate was placed in a 25-ml glass bottle, and 10 g of DMA was added to completely dissolve the silver nitrate. To the solution was added 0.1 g of PVF to obtain a completely dissolved solution. After 2 hours, yellow color appeared in the solution, indicating that the reduction of the silver ion resulted in the generation of silver particles of 0.2 nm in size.

3 is a UV-VIS spectrum of the silver colloid solution obtained in Example 3. Fig. As shown in FIG. 3, a peak due to surface plasmon resonance of silver particles was observed at a wavelength of 400 nm. After 2 hours, the intensity of the surface plasmon resonance peak did not increase any more, confirming that the silver ion reduction reaction was completed.

[Comparative Example]

At 25 ° C, 0.1 g of silver nitrate was placed in a 25-ml glass bottle and 10 g of 1,4-dioxane was added to completely dissolve the silver nitrate. To this solution was added 0.01 g of PVF to obtain a completely dissolved solution. After one day, no yellow color appeared in the solution.

4 is a UV-VIS spectrum of the silver colloid solution obtained in Comparative Example. As can be seen from FIG. 4, no peak due to surface plasmon resonance of silver particles was observed at a wavelength of 420 nm. Compared with Examples 1, 2 and 3, in Comparative Example using an organic solvent of 1,4-Dioxane, the reduction reaction proceeds at a very slow rate even though the compound is a sufficient electron.

Accordingly, the silver colloid of the present invention can be prepared by dissolving silver salt in an organic solvent such as NMP and DMA, and then adding a vinyl polymer such as PVF or PNVC to prepare a silver colloid, It is possible to reduce the process steps and the process cost by eliminating the need for the additive such as the additive, and it is possible to prevent the incorporation of unnecessary foreign substances and to produce silver colloid of high purity.

Claims (8)

Dissolving silver salt in an organic solvent to prepare a mixed solution; And
And dissolving the vinyl polymer in the mixed solution to prepare a silver colloid,
The step of producing the silver colloid is to form nano-sized silver colloid particles without adding a reducing agent and a stabilizer,
Wherein the organic solvent is N-methyl-2-pyrrolidone, N, N-dimethylacetamide or a mixture of the two,
Wherein the vinyl-based polymer is polyvinylformal, poly (N-vinylcarbazole), or a mixture of the two.
The method according to claim 1,
Wherein the silver salt is at least one selected from the group consisting of silver nitrate, silver acetate, silver sulfate and silver iodide.
delete delete delete delete The method according to claim 1,
Wherein each of the steps is carried out at a temperature of 25 to 100 < 0 > C.
The method according to claim 1,
Wherein the silver colloid has a particle size of 0.1 to 100 nm.

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