KR20070032260A - Method of Producing Metal-Containing Particles - Google Patents

Abstract

The present invention relates to a method for producing metal-containing particles. Metal containing particles are micro sized and / or nano sized particles. The particles may have antibacterial properties depending on the metal used. In embodiments in which silver is used, the particles can provide antifungal properties, antistatic properties, electromagnetic interference shielding properties, and / or conducting properties. The particle size may be about 0.01 to about 300 μm.

Metal-containing particles, micro size, nano size, silver nitrate

Description

Method of Producing Metal-Containing Particles {Method of Producing Metal-Containing Particles}

The present invention relates to a process for producing particles, more particularly micro-particles and / or nano-particles.

In recent years, a great deal of attention has been focused on the risk of bacterial contamination by daily potential exposure. Increasing consumer interest in these areas has led manufacturers to introduce antimicrobials to a variety of household products. For example, certain brands of polypropylene cutting boards, liquid soaps, and the like all contain antimicrobial compounds.

In addition, the risk of bacterial contamination is widespread in the medical field. For example, various medical articles are specifically designed to be in contact with the body fluids of a patient. This contact period may be relatively short, as in the case of wound dressing, or may be a long period, as in the case of a prosthetic heart implanted in the recipient's body. Some articles, such as catheters, are capable of both short or relatively long contact periods. Other articles that are in relatively short contact with the patient include, but are not limited to, burn dressings or contact lenses. Other articles in prolonged contact with the patient include, but are not limited to, implanted prostheses.

Contacting body fluids and articles raises the risk of infection. These risks can be very serious and can be life threatening. In addition, infections incur significant costs and may stay in hospital for longer periods or in addition. For example, infections associated with dressings can exacerbate wounds in burn patients. In addition, infections associated with implanted prostheses may require replacement of the device.

Thus, there have been efforts to investigate methods known to help reduce the risk of bacterial infection and / or even prevent infection from development. One approach is to use antibacterial and / or fungicides.

The most popular antimicrobial for many articles is triclosan. Although incorporating such compounds into liquid or polymeric media is relatively simple, it has proven more difficult to incorporate into other substrates, including fabric and fiber surfaces. There is a need for effective, durable and long-lasting antimicrobial properties on fabric surfaces, particularly on garment fabrics and film surfaces. This proposed application is very difficult to achieve when using triclosan, especially when laundry durability is required (triclosan is easily washed off from such surfaces). In addition, although triclosan has proven effective as an antimicrobial compound, it is highly recommended that such antimicrobial compounds be used in conjunction with fibers, films and woven fabrics for use in clothing because hydrochloric acid present in such compounds causes skin irritation. It is not desirable.

There is also a commercial woven fabric comprising acrylic and / or acetate fibers co-molded with triclosan (e.g. Celanese market such as acetate fabrics under the tradename Microsafe ^™ , and under the tradename Amicor ^™ ). Accordis market such as acrylic fibers). However, this application is limited to this type of fiber. That is, it does not apply to natural fibers, in particular to fabrics such as polyester, polyamide, cotton, spandex and the like. In addition, such co-molding procedures are expensive. In addition, antimicrobial inhibitor regions are limited in such applications.

Silver containing inorganic fungicides have recently been developed and used as antibacterial agents in many different substrates and surfaces. In particular, such fungicides are used to impregnate into melt spun synthetic fibers to provide certain fabrics that selectively and uniquely exhibit antimicrobial properties as taught in Japanese Unexamined Patent Application No. H11-124729. In addition, attempts have been made to apply such specific fungicides to the surface of fabrics or yarns but have not been successful in terms of durability. Topical treatments with such compounds as durable finishes or coatings on textile or spun yarn substrate surfaces have not been successfully applied.

Improved techniques exist in the textile art to make silver fabrics in an efficient and / or cost effective way. However, such a method still aims only at the production of silver-containing fibers and fabrics. For example, such fabrics and fibers are not useful because the size of the fabric or fibers is too large for use in the selected application.

Therefore, there is a need for a method of preparing metal based particles having a larger use than known antimicrobial solutions. There is also a need for a method of producing micro- and / or nano-sized silver containing particles.

Summary of the Invention

The present invention provides a method for producing metal containing particles. Metal containing particles are micro sized and / or nano sized particles. The metal is complexed with the alkaline agent to form particles. In one embodiment, the metal is silver and the particles comprise silver hydroxide. The particles have anti-microbial properties. In embodiments in which silver is used, the particles may also provide anti-fungal properties, anti-static properties and / or conductive properties. The particles can have a particle size of about 0.01 to 300 μm.

Such and other embodiments will be described in more detail below.

The present invention is described in more detail through the following description and examples with the intention of illustrating various modifications and changes apparent to those skilled in the art. As used in this specification and claims, the singular forms “a”, “an” and “the” may include the plural meanings unless stated otherwise. Also, as used herein and in the claims, "comprising" may include the meaning of "consisting of" and "consisting essentially of."

The present invention provides a method of making metal based particles. In one aspect, the method of the present invention is used to produce micro-sized and / or nano-sized particles comprising metals. In one embodiment, the metal is silver. Such micro and / or nano size particles can be used for a wide variety of different applications due to their size. Such particles also retain the antibacterial, antifungal, antistatic and / or conductive properties of the metals used. As a result, the micro- and / or nano-sized particles containing silver provide one or more properties such as antimicrobial, antistatic and / or conductive properties.

Thus, in one aspect, the present invention provides a method for producing silver and / or nano sized particles containing silver. In one embodiment, the metal is silver. In other embodiments, the metal may be copper, aluminum, zinc, nickel, or the like. The method produces micro-sized and / or nano-sized particles comprising a metal such as silver. As used herein, “micro sized particles” means particles having a diameter of about 1 to about 300 μm. Depending on the different process parameters, the process uses only the resulting mixture, which is used as a mixture or additionally comprises a separation step of classifying the particles into different size ranges, so that only micro-sized particles, only nano-sized particles or combinations thereof are used. Can be used to manufacture. An example of such a separation step is a screening step that separates particles of different sizes.

The process of the present invention uses a series of process steps to produce such metal containing particles, although not all process steps are necessary in each embodiment. One step is to collect a metal source, such as silver nitrate powder, and dissolve in water for an embodiment of producing silver particles. In one embodiment, the water is deionized water. In another embodiment, the pre-dissolved silver nitrate solution can be used on the premise that the amount of water in the solution is known. The table below describes different embodiments for various amounts of silver nitrate and water that may be used in one embodiment where the silver source is silver nitrate and deionized water is used.

Amount of silver nitrate (g) present in 1 liter of deionized water Primary implementation About 3 to about 500 Secondary implementation About 50 to about 350 Tertiary Embodiment About 100 to about 200 Fourth Embodiment About 150

The solution described above can then be treated with an alkaline solution. In one embodiment, the alkaline solution is sodium hydroxide. Sodium hydroxide can be used because of its strong tendency to form complexes with metal solutions. However, any alkaline solution capable of forming a complex with the metal solution used in certain embodiments may be used in the present invention. In such embodiments, the metal solution is silver nitrate dissolved in DI water. Other alkaline solutions that can be used are, but are not limited to, ammonium hydroxide.

The table below describes different embodiments of the present invention for various amounts of sodium hydroxide that can be used in such embodiments where sodium hydroxide is an alkaline solution. It should be noted that the starting point for preparing the solution is a 50% sodium hydroxide solution (50:50 v / v) readily available from various vendors.

NaOH content from 50:50 (ml) Primary implementation About 10 to about 500 Secondary implementation About 50 to about 300 Tertiary Embodiment About 75 to about 150 Fourth Embodiment About 100

The reaction can take place at room temperature, or from about 15 to about 30 ° C. During the reaction, the alkaline solution forms a complex with the metal to form a precipitate containing the metal. In such embodiments in which sodium hydroxide is used, brown precipitates are produced by the addition of sodium hydroxide. The solution can be stirred while the precipitate is produced. After all the alkaline solution has been added, the resulting mixture can be allowed to stand for a period of time to allow the precipitate to settle. Settling time may vary and may be about 5 to about 15 minutes.

Remove the precipitate after settling. The precipitate can be filtered using standard filter papers such as Buckner funnel. The solution may be neutralized depending on the pH of the solution. Since alkaline solutions generally increase the pH above 7, an acid can be used to prepare a solution of about pH 7. In one embodiment, sulfuric acid may be used, although not limited thereto, although other acids, including hydrochloric acid and nitric acid, may be used among the various acids. Adjusting the pH of the solution to about 7 has the advantage of facilitating easy treatment in terms of waste treatment, although such steps are not required for the preparation of the micro and nano size particles of the present invention.

The precipitate is then washed with water, such as deionized water. It is advantageous to use water to thoroughly wash out the precipitate. Cleaning the precipitate helps to collect nano and micro sized particles of complexed metal precipitates in pure form. In one embodiment where silver is a metal and sodium hydroxide is an alkaline solution, the resulting precipitate contains nano and micro size silver hydroxide particles. The cleaning may be performed at any location, including inside its funnel.

The precipitate may then be dried in a known oven or by another drying mechanism until the precipitate is substantially dried. In one embodiment, the drying temperature is about 50 to about 90 ° C. The product produced after drying the precipitate comprises the micro and / or nano size particles of the invention.

It is to be understood that the micro and / or nano sized particles of the present invention contain silver so that useful properties of silver can be retained even in smaller sized particles. As a result, the particles of the present invention can be used in any application that utilizes the useful properties of one or more silver. Such properties include, but are not limited to, antibacterial, antifungal, antistatic, conductive, electromagnetic interference (EMI) shielding, filtering, or combinations thereof.

The invention will be further described by way of examples. It should be noted that such embodiments are not intended to limit the present invention, but are provided to more easily understand various embodiments of the present invention.

Example 1

75 g silver nitrate was weighed. It was then dissolved in 500 ml deionized water at room temperature (about 22 ° C.). After the salt was dissolved the final volume was brought to 600 ml. 100 ml of 50:50 NaOH was slowly added dropwise to the silver nitrate solution. A brown precipitate formed immediately. The solution from which the precipitate formed was then stirred with a rod. The mixture was then left to stand for about 10 minutes. The precipitate was filtered using Buckner funnel, a standard filter paper.

The solution was neutralized with 50% sulfuric acid. Then, the precipitate was washed with 50-100 ml deionized water for a period of time through a Buckner funnel. In this example, 5000 ml of deionized water (DI) was used to wash the precipitate.

The resulting precipitate was dried in a known oven until it dried at about 60-80 ° C.

About 46 g of brown silver hydroxide nano and micro size particles were obtained.

Example 2

The nanopowders obtained from Example 1 were heat treated for a few minutes at high temperature (ie at least about 100 ° C.). Through heat treatment, shiny white micro size and nano size silver particles were prepared. The resulting powder is about 43 g.

Example 3

The resulting powder obtained in Example 1 contained a weight ratio of hydrogel to silver powder on the outer surface of the hydrogel bandage at 10: 1. The surface was impregnated to apply the hydrogel mixture to the surface. This sample was then treated with Dow Corning Corporate Test Method 0923 using Staphylococcus aureus ATCC 6538. After 1 hour, viable cell count (CFU / ml) decreased to less than 10 at 1.6 × 10 ⁵ CFU / ml at the first hour. The reduction rate was over 99.99%. As a result, the antimicrobial properties of the micro and nano size silver hydroxide particles were clearly verified.

Example 4

The resulting powder obtained in Example 1 contained a weight ratio of hydrogel to silver powder of 10: 1 on the outer surface of the hydrogel bandage, and then the same test as in Example 3 was conducted for at least 4 hours. The reduction rate was over 99.99%. These results indicate that nanoparticles have a large surface area and are effective in small amounts.

Example 5

The resulting powder obtained in Example 1 was included in a weight ratio of hydrogel to silver powder of 100: 1 on the outer surface of the hydrogel bandage, and then the same test as in Example 3 was conducted for at least 4 hours. The reduction rate is 94%, which again shows the efficiency and surface area benefits of the nanoparticles. The test results also show a huge inhibition zone of the nanoparticles.

The foregoing description is provided for the purpose of illustrating, describing, and describing embodiments of the present invention. Modifications and adaptations of such embodiments will be apparent to those skilled in the art, and may be performed without departing from the scope or spirit of the invention.

Claims (20)

Preparing a metal solution in which a metal is dissolved in a solvent; Mixing the metal solution with the alkaline solution to prepare a precipitate comprising a metal; Separating the precipitate; And Drying the precipitate to produce metal-containing particles Method for producing a metal-containing particles comprising a. The method of claim 1, wherein the metal is selected from silver, copper, nickel, zinc, aluminum, or a combination thereof. The method of claim 2, wherein the metal is silver. The method of claim 1 wherein the metal containing particle size is about 0.01 μm to about 300 μm. The method of claim 4, wherein the metal containing particle size is about 1 μm to about 300 μm. The method of claim 4, wherein the metal containing particle size is about 0.01 μm to about 1 μm. The process according to claim 1, wherein the method further comprises the step of washing the precipitate with water prior to the drying step. The method according to claim 1, wherein the metal solution in which the metal is dissolved in the solvent comprises silver nitrate powder dissolved in water. 9. A process according to claim 8 wherein the content of silver nitrate is from about 3 g to about 500 g per liter of water. 10. A process according to claim 9 wherein the content of silver nitrate is from about 100 g to about 200 g per liter of water. The method of claim 1 wherein the alkaline solution is selected from sodium hydroxide, ammonium hydroxide or a combination thereof. 12. The process according to claim 11, wherein said alkaline solution is sodium hydroxide. The method of claim 12, wherein the sodium hydroxide solution is a 50% (v / v) sodium hydroxide solution. Particles prepared by the method of claim 1. The particle of claim 1, wherein the metal is selected from silver, copper, nickel, zinc, aluminum, or a combination thereof. The particle of claim 15, wherein the metal is silver. The particle of claim 14, wherein the metal containing particle size is about 0.01 μm to about 300 μm. 18. The particle of claim 17, wherein the metal containing particle size is about 1 μm to about 300 μm. 18. The particle of claim 17, wherein the metal containing particle size is about 0.01 μm to about 1 μm. Silver hydroxide particles comprising silver complexed with hydroxide and having a particle diameter of about 0.01 μm to about 300 μm.