KR100479847B1 - Stable metal colloids with uniform shape and narrow size distribution and a method for preparation thereof - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to metal colloids having excellent stability, uniform shape and narrow particle distribution of nanometer size and methods for their preparation, more specifically (1-vinyl pyrrolidone) -acrylic acid copolymer {poly (1-vinyl pyrrolidone-co-acrylic acid}, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer {poly (1-vinyl pyrrolidone-co-vinyl acetate)} as stabilizers It relates to a metal colloid and a method for producing the same.

According to the present invention, silver nanoparticle solutions having a uniform particle size, particle distribution and shape at room temperature can be prepared in large quantities. In addition, since silver nanoparticles of very small size are used, the volume-to-surface area ratio is very large and shows excellent antimicrobial activity even when using a very small amount. Therefore, the silver nanoparticles of the present invention can be used in antibacterial agents, bactericides, deodorants, electromagnetic wave shielding agents, conductive adhesives, conductive inks.

Description

Stable metal colloids with uniform shape and narrow size distribution and a method for preparation according to the present invention.

FIELD OF THE INVENTION The present invention relates to metal colloids having excellent stability, uniform shape and narrow particle distribution of nanometer size and methods for their preparation, more specifically (1-vinyl pyrrolidone) -acrylic acid copolymer {poly (1-vinyl pyrrolidone-co-acrylic acid}, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer {poly (1-vinyl pyrrolidone-co-vinyl acetate)} as stabilizers It relates to a metal colloid and a method for producing the same.

The preparation of metal nanoparticle colloids using gamma rays has recently been developed, and a method for preparing silver colloids in dispersed state using suitable stabilizers such as poly (vinyl alcohol) and SDS (sodium dodecyl sulfate) has been developed. ( Nature 1985 , 317, 344, Materials Letters 1993 , 17 , 314). The methods using gamma rays aim to uniformly disperse the silver nanoparticles in the solvent, but the particle size of the metals produced by these methods has been reported to be about 8 nm to several tens of nm in the best studies. And uniformity of shape is not so good.

Obtaining pure silver with a narrow particle distribution and uniform shape is very important for industrial applications (see Materials Letters 1993 , 17 , 314). For example, in the electronics industry, ultrafine silver particles are conductive inks, pastes, and adhesives that are important for the manufacture of various electronic components (see Metals Handbook ; American Society for Metals: Metals Park, 1984 , 9th Ed., Vol. 7). ).

As can be seen from above, new methods of manufacturing metal nanoparticles as well as particle size control, particle distribution and particle shape uniformity are still areas to be improved and developed. In addition, good dispersion stability that does not aggregate in the metal nanoparticles dispersed in the solvent is an essential task to be achieved for industrial applications. In addition, in order to be compatible with various organic solvents, plasticizers, resins and the like for the diversity of industrial applications, it is also essential to prepare a metal colloidal solution dispersed in a non-aqueous solution.

Accordingly, the present inventors have diligently researched to overcome the problems of the prior art, and as a result, (1-vinyl pyrrolidone) -acrylic acid copolymer, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer When using the as a stabilizer to prepare a metal colloid was confirmed that the excellent stability and uniform shape and obtain a narrow particle distribution effect, to complete the present invention.

Therefore, the main object of the present invention is to provide excellent stability and uniformity by using (1-vinyl pyrrolidone) -acrylic acid copolymer, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer as stabilizers. To provide a metal colloidal solution having a shape and a narrow particle distribution effect and a method for producing the same.

In order to achieve the object of the present invention, the present invention is a metal salt or metal oxide salt and (1-vinyl pyrrolidone) -acrylic acid copolymer, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer One or more polymer stabilizers selected from the group consisting of dissolved in water or a non-aqueous solvent, purge with nitrogen, and then provide a method for producing a metal nanoparticle colloidal solution characterized in that irradiating gamma rays.

In order to achieve another object of the present invention, the present invention provides a metal nanoparticle colloidal solution prepared by the above method.

The metal salts of the invention are selected from the group consisting of Ag salts, Cu salts, Ni salts, Pd salts and Pt salts and metal oxide salts such as TiO ₂ can also be used.

The non-aqueous solvent basically serves to remove radicals after gamma ray treatment in addition to a solvent for dissolving a metal salt or a metal oxide salt and a polymer stabilizer. As such a non-aqueous solvent, at least one selected from the group consisting of ethylene glycol, methanol and isopropyl alcohol is used.

The configuration of the present invention can be described in more detail by exemplifying the preparation of the silver nanoparticle colloidal solution.

As a source of silver, silver salts such as AgNO ₃ , AgClO ₄ , Ag ₂ SO ₄ or CH ₃ COOAg are used. The silver salts mentioned above dissolve well in water and eventually form water-soluble silver nanoparticle colloids. From the group consisting of (1-vinyl pyrrolidone) -acrylic acid copolymer, polyoxyethylene stearate and (1-vinyl pyrrolidone) -vinyl acetate copolymer as stabilizers for excellent dispersibility of silver nanoparticles in the present invention Using more than one produces a stable silver nanoparticle colloidal solution.

The mixing weight ratio of the 1-vinyl pyrrolidone repeating unit and the acrylic acid repeating unit in the (1-vinyl pyrrolidone) -acrylic acid copolymer is preferably 1:99 to 99: 1, especially 75:25, The mixing weight ratio of the 1-vinyl pyrrolidone repeating unit and the vinyl acetate repeating unit in the vinyl pyrrolidone) -vinyl acetate copolymer is preferably 1:99 to 99: 1, especially 57:43.

The polymer stabilizer is used in the range of 0.5 to 5 parts by weight based on 100 parts by weight of the solvent, and the silver salt is used in an amount of 0.01 to 1 parts by weight based on 100 parts by weight of the solvent.

The polymer stabilizer and silver salt are completely dissolved in the solvent and purged with nitrogen gas (N ₂ ) in the mixture for 30 minutes to 1 hour and then the vessel is completely sealed.

Subsequently, irradiating gamma rays with a 10 to 30 KGy linewidth on the resulting silver nanoparticles with a much smaller particle size (1-5 nm) and narrower particle distribution (1-5 nm) than those produced by conventional methods Particle colloidal solutions are prepared.

Korean Patent Application No. 2001-23471 discloses a method for preparing nanometer-sized silver colloids by irradiating radiation after dissolving silver salts in water using polyvinylpyrrolidone (PVP) as a stabilizer. The size of the particles is not preferable as about 60 nm.

In the present invention, the average size of the silver nanoparticles prepared using the (1-vinyl pyrrolidone) -acrylic acid copolymer as a stabilizer is 3.0 ± 0.89 nm, which is higher than that prepared by the method disclosed in Korean Patent Application No. 2001-23471. It has a much smaller particle size and a narrow particle distribution (FIG. 1).

The reason for the larger particle size than the conventional method is that the conventional method disclosed in Korean Patent Application No. 2001-23471 uses PVP as a stabilizer, but in the present invention, (1-vinyl pyrrolidone) -acrylic acid copolymer, poly At least one polymer stabilizer selected from the group consisting of oxyethylenestearate and (1-vinyl pyrrolidone) -vinyl acetate copolymers. In addition, the stabilizers of the present invention allows the formation of silver colloids in water as well as non-aqueous solvents such as ethylene glycol, methanol or isopropyl alcohol.

Such small size silver nanoparticles have a very large volume-to-surface area ratio and exhibit excellent antimicrobial activity even when very small amounts are used. Therefore, the silver nanoparticles can be used as an antimicrobial agent, bactericide, deodorant, electromagnetic wave shielding agent, conductive adhesive, conductive ink.

The variety of industrial applications requires compatibility with various organic solvents, plasticizers, resins, and the like. Therefore, preparation of silver colloidal solutions dispersed in non-aqueous solutions is also essential. In this case, when ethylene glycol is used as the solvent, silver nanoparticle colloid can be produced even in non-aqueous solution. Although isopropyl alcohol is used as a scavenger to remove the radicals formed by gamma rays, ethylene glycol can also act as a scavenger in non-aqueous solutions using ethylene glycol as a solvent, so it is unnecessary to add isopropyl alcohol. do.

In addition to the non-aqueous solution synthesis method such as ethylene glycol in order to have compatibility with various resins, plasticizers and solvents, isopropyl alcohol as a solvent and scavenger instead of water is compatible with alcohol-soluble resin, plasticizer DOP (dioctyl phthalate) and organic solvents. Have a last name

The present invention shows that silver nanoparticle colloidal solution can be produced even in non-aqueous solution using ethylene glycol as a solvent. The silver nanoparticles have a size of 1.5-4 nm (mean approximately 2 nm) and are very small (Figure 5). When ethylene glycol is used as the solvent, it is economical because the isopropyl alcohol used as the scavenger is economical and the risk of explosion is low.

Hereinafter, the present invention will be described in more detail with reference to Examples. Since these examples are only for illustrating the present invention, the scope of the present invention is not to be construed as being limited by these examples.

Example 9 1: Silver nanoparticles prepared using water as solvent and (1-vinyl pyrrolidone) -acrylic acid copolymer as stabilizer

In 592 g of water, 1.863 g of AgNO ₃ , 395 g of isopropyl alcohol and 11.137 g of (1-vinyl pyrrolidone) -acrylic acid copolymer (MW 96,000) in a 75:25 mixed weight ratio are completely dissolved. Purge with N ₂ gas for 1 hour and seal the container completely. Gamma-ray treatment is carried out to make the 30KGy line width. This gives a yellow nanoparticle colloidal solution. The particle distribution is relatively even and the shape is uniform. The particle size is mostly the smallest of the silver nanoparticles reported so far by the gamma ray method with an average size of 3.0 ± 0.89 nm (FIG. 1). From the particle distribution diagram of FIG. 1, it can be seen that the particle distribution is quite narrow.

UV / VIS spectra were taken to confirm that silver nanoparticles were actually formed, and it can be seen that absorption bands of silver nanoparticles appeared at 405 nm (FIG. 2).

Example 2: Silver nanoparticles prepared using water as solvent and polyoxyethylene stearate as stabilizer.

Dissolve 1.863 g of AgNO ₃ , 395 g of isopropyl alcohol and 11.137 g of polyoxyethylene stearate in 592 g of water in the same amount as in Example 1. In this case, the average size of the prepared silver nanoparticles is 7.54 ± 1.79 nm. It can be seen from the particle distribution chart that the particle distribution is quite narrow (FIG. 3).

UV / VIS spectrum was taken to confirm that silver nanoparticles were actually formed, and it can be seen that absorption bands of silver nanoparticles appeared at 405 nm (FIG. 4).

Example 3 Silver Nanoparticles Prepared Using Ethylene Glycol as Solvent and Polyacrylic Acid as Stabilizer

Dissolve 1.863 g of AgNO _{3 and} 395 g of isopropyl alcohol in 592 g of ethylene glycol. To this is added 1.863 g polyacrylic acid (MW 2,000) and an isopropyl alcohol or methanol solution with NaOH dissolved to bring the pH of the solution to 11. Purge with N ₂ gas for 1 hour and seal the container completely. Gamma-ray treatment is carried out to make the 30KGy line width. The yellow silver nanoparticle colloid can then be obtained from non-aqueous solution.

The size and distribution of silver nanoparticles in the silver nanoparticle colloid prepared according to Example 3 were investigated using a transmission electron microscope (TEM), and the results are shown in FIG. 5. Referring to FIG. 5, the size and distribution of silver nanoparticles is very small, 1.5-4 nm (approximately average particle size is 2 nm). The same result is obtained here using the (1-vinyl pyrrolidone) -acrylic acid copolymer and polyoxyethylene stearate of Example 1 instead of polyacrylic acid, where NaOH need not be added. In addition, when ethylene glycol is used in such a non-aqueous solution preparation method, silver nanoparticle colloidal solution is produced even without adding scavenger isopropyl alcohol.

UV / VIS spectra were taken to confirm that silver nanoparticles were actually formed, and it can be seen that absorption bands of silver nanoparticles appeared at 405 nm (FIG. 6).

In Examples 1, 2, or 3, a stable silver nanoparticle colloidal solution can be obtained by using isopropyl alcohol instead of a solvent such as water or ethylene glycol.

According to the present invention, silver nanoparticle solutions having a uniform particle size, particle distribution and shape at room temperature can be prepared in large quantities. Conventional methods using reducing agents are difficult to have uniform particle characteristics when produced in large quantities. In addition, since silver nanoparticles of very small size are used, the volume-to-surface area ratio is very large and shows excellent antimicrobial activity even when a very small amount is used.

1 is a transmission electron microscope (TEM) photograph of silver nanoparticles prepared using water as a solvent and a (1-vinyl pyrrolidone) -acrylic acid copolymer as a stabilizer according to Example 1 of the present invention and particles thereof It is a distribution chart.

2 is a UV / VIS absorption spectrum at 405 nm of silver nanoparticles made according to Example 1 of the present invention.

3 is a transmission electron microscope (TEM) photograph of silver nanoparticles prepared using water as a solvent and polyoxyethylene stearate as a stabilizer according to Example 2 of the present invention, and a particle distribution thereof.

4 is a UV / VIS absorption spectrum at 405 nm of silver nanoparticles made according to Example 2 of the present invention.

FIG. 5 is a transmission electron micrograph of silver nanoparticles prepared using ethylene glycol as a solvent and a polyacrylic acid stabilizer according to Example 3 of the present invention.

6 is a UV / VIS absorption spectrum at 405 nm of silver nanoparticles made according to Example 3 of the present invention.

Claims (7)

At least one polymer stabilizer selected from the group consisting of metal salts or metal oxide salts, and (1-vinyl pyrrolidone) -acrylic acid copolymers, polyoxyethylene stearate, and (1-vinyl pyrrolidone) -vinyl acetate copolymers; Or dissolving in a non-aqueous solvent, purging with nitrogen, and then irradiating with gamma rays. The method of claim 1 wherein the metal salt is an Ag, Cu, Ni, Pd or Pt containing salt and the metal oxide salt is a TiO ₂ containing salt. The method of claim 2, wherein the metal salt is at least one selected from the group consisting of AgNO ₃ , AgClO ₄ , Ag ₂ SO ₄ or CH ₃ COOAg. The method of claim 1, wherein the non-aqueous solvent is at least one selected from the group consisting of ethylene glycol, methanol and isopropyl alcohol. The metal nanoparticle colloidal solution prepared by any one of claims 1 to 4, wherein the metal nanoparticles have a size of 1-5 nm. delete The colloidal metal nanoparticle solution according to claim 5, which is used as an antimicrobial agent, a deodorant, a bactericide, a conductive adhesive, a conductive ink, and an electromagnetic shielding film of an image display device.