Mass production method of nano silver, manufacturing method of germicide fiber coated with nano silver and its products
WO 2006135128 A1
Disclosed
herein are a method of mass-producing nanosilver, a method of
manufacturing nanosilver-coated antibacterial fiber, and antibacterial
fiber manufactured thereby. Nanosilver having a size of 5 nm or less can
be produced on a mass scale by applying an electric field of 10,000 to
300,000 volts (DC) across two Ag electrode plates equipped in a water
electrolysis system and allowing only a microcurrent to flow between the
electrode plates. The nanosilver-coated, antibacterial fiber is
manufactured by applying a aqeous solution of the nanosilver to the
surface of the synthetic fibers, adsorbing the nanosilver onto the cloth
using a process selected from the group consisting of thermal fixation,
high frequency radiation, bubbling, and combinations thereof; and
conducting a post-finishing at 160 to 200°C. And thus, an antibacterial
fiber manufactured thereby may be a fundamental solution to the
synthetic fiber's problems, that is, poor perspiration functionality and
the generation of statistic electricity.
Claims (OCR text may contain errors)
[CLAIMS]
[Claim l]
A method of the mass production of
nanosilver, comprising: applying an electric field of 10,000 to 300,000
volts (DC) across two Ag electrode plates equipped in a water
electrolysis system; and allowing only a microcurrent to flow between
the electrode plates. [Claim 2]
The method as set forth in claim 1, wherein
the water hydrolysis system comprises a water reservoir provided with a
water inlet valve for introducing water thereinto and a water outlet
valve for draining water therefrom and filled with water so as to
immerse the Ag electrode plates, said two Ag electrode plates, each
connected to a power source
(DC+, DC-) , being provided on opposite
sides of the water reservoir, respectively, the current flowing between
said Ag electrode plates being controlled by moving a circuit breaker
upwards or downwards along a groove formed in a middle portion of the
water reservoir to divide the water reservoir into two compartments, in
the presence of a high voltage of 10,000 to 300,000 volts (DC+, DC-).
[Claim 3] The method as set forth in claim 1, wherein the
nanosilver ranges in size from 1 to 5 ran. [Claim 4]
A method of manufacturing nanosilver-coated
antibacterial fiber comprises: preparing a aqueous solution of the
nanosilver prepared by the method of claim 1; continuously scouring and
washing synthetic fibers; applying the aqueous solution of the
nanosilver to the surface of the synthetic fibers; adsorbing the
nanosilver onto the synthetic fibers using a process selected from among
thermal fixation, high frequency radiation, bubbling, and combinations
thereof; and conducting a post-finishing at 160 to 200°C. [Claim 5] The method as set forth in claim 4, further comprising a dyeing process before the post-finishing. [Claim 6]
The method as set forth in claim 4, wherein the thermal fixation is carried out at a temperature from 150 to 230°C.
[Claim 7]
The method as set forth in claim 4, wherein
the aqueous solution contains nanosilver in an amount of 10 to 100 ppm.
[Claim 8]
The method as set forth in claim 4, wherein the application step of the
aqueous solution containing the nanosilver is carried out in a process
selected from the group consisting of a spraying process, a coating
process, and a dipping process. [Claim 9l
An antibacterial fiber, having nanosilver
adsorbed thereon in an amount of 0.01 to 0.1 g per 100 g of synthetic
fibers, and being produced according to the method of claim 4.
Description (OCR text may contain errors)
[DESCRIPTION]
[invention Title] MASS PRODUCTION METHOD OF NANO SILVER, MANUFACTURING METHOD OF GERMICIDE FIBER COATED WITH NANO SILVER AND ITS PRODUCTS [Technical Field] The present invention relates to a method of mass- producing nanosilver, a method of manufacturing nanosilver- coated antibacterial fiber, and antibacterial fiber manufactured thereby. More particularly, the present invention relates to the mass production of nanosilver having a size of 5 nm or lower by allowing only a microcurrent to flow between two opposite silver electrode plates in the presence of a high voltage in a water electrolysis system, a method of manufacturing nanosilver- coated, antibacterial fiber by taking advantage of the better applicability of smaller silver particles, and antibacterial fiber and cloth coated with nanosilver. [Background Art] Microbes are everywhere. A variety of microbes are found in large quantities in daily living environments. Particularly, they grow and proliferate on clothes and form flora even on the skin. While they inhabit clothes, microbes degrade fibers or digest nutrients in sweat or contaminants, producing bad odors or causing a great damage to the health of humans. WHO reports disclose that microbial contamination is responsible for about 30% of the mortality in the world. In fact, current scientific technologies fall short of sufficiently controlling harmful microbes. Extensive effort is now being made to develop antimicrobial/germicidal agents or products that are harmless to human bodies and have better improved functions. Long and extensive experiences and experiments have revealed that silver can control almost all single cell pathogens in the world. Having such antimicrobial activity, silver has been long used in a wide range of fields, for example, tableware, such as bowls, spoons, chopsticks, etc., and herbal medicines such as silver-coated pills. As for the antibacterial function of silver, it is reportedly based on the activity of inhibiting certain enzymatic reactions essential for the metabolism of pathogens and thus killing them. Particularly in association with nano technology, silver in a nano state exhibits potent antibacterial and germicidal activity. Many research results report that silver in a nano state can kill as many as 650 kinds of bacteria and other microbes and shows excellent inhibitory activity against fungi. As they become smaller in size, silver particles have more potent antibacterial/germicidal activity due to the increase in surface area. According to experimental data, silver powders show 99.9% antibacterial and germicidal efficiency over a variety of bacteria, including enterobacteria, Staphylococcus aureus, Salmonella, Vibrio, shigella, Pneumococcus, typoid, and even MRSA (methicillin resistant staphylococcus aureus) . Reportedly, almost no bacteria can survive 5 min or longer contact with nanosilver. Nanosilver has tens fold more potent inhibitory activity against bacteria than have chloride-based agents, and does not damage human bodies at all; therefore it is expected to be a useful therapeutic agent against various inflammations. In addition, taking advantage of nanosilver, various functional products having antibacterial and deodorizing activity are on the market. In the fiber and textile industry, accordingly, it is very important to produce nanosilver having such excellent effects on a large scale and to effectively incorporate the nanosilver into fibers. For past tens of years, synthetic fibers have been used in a wide range of fields of human life as complements to or substitutes for natural fibers and even as materials that are functionally superior to natural fibers. During the period, synthetic fibers for clothes have been developed towards practicality, comfort, and other functionalities. Recently, active research has been made on environment- and body-friendly synthetic fibers. In a persistent effort to develop these synthetic fibers, the antibacterial activity of nanosilver is applied to fibers. Conventionally, nanosilver is extracted using a physical method, such as liquid phase reduction, grinding, etc., or an electrolytic method in which, after silver (99.9%) is added to distilled water, silver-containing compounds are electrolyzed and the electolysates are subjected to electrophoresis by taking advantage of the (+) and (-) poles that each molecule possesses, so as to collect silver. The other hands, as a representative method to intercalate nanosilver into fibers, synthetic fibers are manufactured by mixing nanosilver with raw synthetic fiber materials before the synthetic fibers are spun. However, the fibers, which are synthesized in the above mentioned method, is poor in antibacterial or germicidal activity because most silver is deeply intercalated into synthetic fibers while only a small amount of silver is exposed on the surfaces of synthetic fibers. Alternatively, antibacterial agents, such as silver, silver oxide, nanosilver etc., are coated onto synthetic fibers. However, the antibacterial agents have poor adhesive strength with synthetic fibers; therefore the synthetic fibers are inferior to washing durability. Leading to the present invention, intensive and thorough research, conducted by the present inventors, on antibacterial fiber and cloth resulted in the finding that nanosilver must be exposed in a larger amount on the surface of synthetic fibers, rather than be embedded within them, in order to maximize the germicidal or antibacterial effect of silver. The smaller the synthetic fibers are more powerful antibacterial/germicidal activities are. Also, In order to obtain the smaller nanosilver, it is designed that the mass production of nanosilver is generated by controlling a current under a high voltage in a water electrolysis system. [Disclosure] [Technical Problem] Therefore, it is an object of the present invention to provide a method of mass-producing nanosilver by applying a high voltage to a water electrolysis system. It is another object of the present invention to provide a method of manufacturing antibacterial fiber having nanosilver applied in a large quantity thereon. It is a further object of the present invention to provide an antibacterial fiber or cloth coated with nanosilver. [Technical Solution] In accordance with an aspect of the present invention, the above objects could be accomplished by a provision of a method for the mass production of nanosilver. More practically, the nanosilver on a large scale is generated by applying an electric field of 10,000 to 300,000 volts (DC) across two Ag electrode plates equipped in a water electrolysis system; and allowing only a microcurrent to flow between the electrode plates. Wherein, the water electrolysis system comprises: a water reservoir (101) provided with a water inlet valve (102) for introducing water thereinto and a water outlet valve (103) for draining the water therefrom; the two Ag electrode plates (104, 105) connected to a DC+ electric power source and a DC- electric power source respectively, the two Ag electrodes (104, 105) being provided on respective opposite sides of the water reservoir (101) ; a circuit breaker (107) for dividing the water reservoir into two sections, being provided in a middle of the water reservoir; and a groove (106) for the circuit breaker (107) , being formed in a middle portion of the water reservoir. Preferably, the nanosilver ranges in size from 1 to 5 nm. In accordance with another aspect of the present invention, a method for manufacturing nanosilver-adsorbed fiber that nanosilver is intensively adsorbed on surface of synthetic fibers. More practically, the method is comprising; preparing aqueous solution containing the nanosilver on a large scale; scouring and washing synthetic fibers; applying the aqueous solution containing the nanosilver to the surface of the synthetic fibers; adsorbing the nanosilver onto the synthetic fibers using a process selected from the group consisting of thermal fixation, high frequency radiation, bubbling, and combinations thereof; and conducting post-finishing at 160 to 200°C. The method may further comprise a dyeing step before the post-finishing. Preferably, the thermal fixation is carried out at a temperature from 150 to 230°C. The aqueous solution containing the nanosilver is in an amount of 10 to 100 ppm of the nanosilver. The step of applying the aqueous solution containing the nanosilver to the surface of the synthetic fibers is preferable to conducting a process selected from the group consisting of spraying, coating, and dipping. In accordance with a further aspect of the present invention, an antibacterial fiber manufactured thereby, in which antibacterial fiber has the nanosilver has adsorbed thereon in an amount of 0.01 to 0.1 g per 100 g of synthetic fibers . [Advantageous Effects] The present invention provides a method for producing nanosilver on a large scale by applying a high voltage in water electrolysis system, and an antibacterial fiber having intensively nanosilver adsorbed thereon. [Description of Drawings] FIG. 1 shows a device for preparing the solution containing the nanosilver in accordance with the present invention, FIG. 2 shows the particle distribution prepared in the presence of a high voltage in the aqueous solution containing the nanosilver according to the present invention, and FIG. 3 shows the particle distribution prepared in the presence of a low voltage in the aqueous solution containing the nanosilver according to conventional method. <The number explanation in the figures> 101: a water reservoir 102: a water inlet valve 103 a water outlet valve 104,105: Ag electrode plates 106: a groove in the water reservoir 107: a circuit breaker [Best Mode] Hereinafter, the present invention is described in detail. In accordance with one aspect, the present invention provides a method of mass-producing nanosilver is provided, based on the electrolysis of water in which while being applied across two electrodes, each made from an Ag plate, a high voltage from 10,000 to 300,000 V is controlled with a microcurrent . With reference to FIG. 1, the method for the mass production of nanosilver according to the present invention is explained in detail. A water reservoir (101) provided with a water inlet valve (102) for introducing water thereinto and a water outlet valve (103) for draining water therefrom has two Ag plates (104, 105), each connected to a power source (DC+, DC-), on its opposite sides. Fitted into a groove (106), a circuit breaker (107) is installed in a middle portion of the water reservoir (101) to divide the water reservoir into two compartments. After water is introduced in an amount sufficient to immerse the two Ag plates (104, 105), a high voltage of 10,000 ~ 300,000V (DC+, DC-) is applied across the two Ag plates, with the circuit breaker (107) moving up and down to control the electric current with respect to the high voltage. It will be readily understood by those skilled in the art that the water reservoir, the water inlet valve, the water outlet valve, and the circuit breaker are all electrically insulated. Generally speaking, a current rises as a voltage increases, in accordance with the following Formula 1. Thus, electric currents can be controlled under low voltages, using circuits, diodes and the like, but current control is generally impossible under high voltages. [Formula l] Voltage (V) = Current (I) x Resistance (R) The present invention features current control under a high voltage from 10,000 to 300,000 V during water electrolysis. The circuit breaker (107) installed at a middle portion of the reservoir is moved upwards or downwards to allow only a microcurrent to flow through the two electrodes, thereby producing silver particles in a nano size. In more detail, the behavior of the current flowing through the reservoir in the presence of a certain voltage follows Formula 1 when the circuit breaker (107) is absent. The current decreases to half when the circuit breaker (107) is controlled to block half of the reservoir's cross sectional area perpendicular to the current direction. Thus, since the current flowing between the two Ag electrodes decreases as the height of the circuit breaker decreases, only infinitesimal currents is allowed to flow so as to produce nanosilver. The current control is conducted until the nanosilver size becomes 5 nm or less and preferably 1 to 5 nm. When exceeding 5 nm in size, silver particles lose the property of being easily applied, which is characteristic of nanosilver, because their surface area is decreased. In addition, if the current amount is not controlled, silver ions are not isolated as particles, but silver plating occurs. With reference to FIG. 2, there is a photograph of the particle distribution prepared in the presence of a high voltage in the aqueous solution containing the nanosilver according to the present invention, taken using a scanning electron microscopy, showing that the nanosilver having a size of 5 nm or less is uniformly distributed. FIG. 3 is a scanning electron microscopic photograph of an aqueous solution containing the nanosilver prepared in the presence of a low voltage, showing that the particles are non- uniformly distributed, with aggregations found therein. In addition, the nanosilver prepared according to the method of the present invention is in an aqueous solution state so that it can be coated and adsorbed onto synthetic fibers uniformly and readily. In accordance with another aspect of the present invention, a method of manufacturing nanosilver-adsorbed fiber is provided, which comprises preparing an aqueous solution of nanosilver, obtained by the mass production method, scouring and washing synthetic fibers, applying the aqueous silver solution on the surface of the synthetic fibers, fixedly adsorbing the nanosilver onto the surface of the synthetic fibers through thermal fixation, high- frequency radiation, or bubbling, and post-finishing the cloth at 160 to 200°C. The method may further comprise a dyeing step before the post-finishing. The application of nanosilver may be carried out on general cloth types, including leather, natural fibers, and synthetic fibers, and preferably with synthetic fibers. The term "synthetic fibers" as used herein means generic fibers made from chemical materials, such as polyester, nylon, acryl, etc. Particularly, synthetic fiber has smooth surface such that the nanosilver can be easily adsorbed thereon, in contrast with natural fibers consisting of warp and weft. In the case of natural fibers, nanosilver is deeply intercalated into natural fibers, thus antimicrobial activity is poor. The application of a aqueous solution of nanosilver to the surface of synthetic fibers may be carried out using a spraying method, a coating method, or a dipping method in which impregnation is followed by coating using a knife or a roll knife. The antibacterial fiber is preferably adsorbed with nanosilver in an amount of 0.01 to 0.1 g per 100 g of synthetic fibers. The present invention can apply nanosilver in relatively large amounts, as compared to conventional methods. When nanosilver is used in an amount of less than 0.01 g, the synthetic fiber has insufficient antibacterial activity. On the other hand, if the amount of the nanosilver applied is more than 0.1 g, the production cost excessively increases relative to the improvement of antibacterial effects. Next, the adsorption of the nanosilver onto the surface of synthetic fibers may be achieved using various processes. An example of preferred processes is thermal fixation at 150 to 230°C. The thermal fixation process serves to make the cloth flexible enough to introduce the nanosilver solution thereonto as well as to fixedly coat nanosilver onto the surface of the synthetic fibers. When the temperature is below 150 °C, the raw fibers are too flexible. On the other hand, thermal fixation at temperatures higher than 230°C makes the raw fibers too stiff. Thermal fixation at 150 to 230 °C requires about 2 atm. Another process for the adsorption of the nanosilver onto the surface of the synthetic fibers uses high-frequency radiation. The high-frequency radiation suitable for the coating has an ultrasonic wave frequency that exceeds the upper limit of the range of audio frequency (16 to 16000Hz) . Generally, ultrasonic waves may be generated by applying an ultrasonic signal produced in an electric circuit to an ultrasonic oscillator. The irradiation of ultrasonic waves onto the aqueous solution produces innumerable fine voids which are helpful in introducing the nanosilver solution onto the surface of synthetic fibers. Another process for the adsorption of the nanosilver onto the surface of the synthetic fibers may be accomplished through bubbling. In this process, nanosilver particles ionized by electrolysis, which oscillate leftwards and rightwards, upwards and downwards, or backwards and forwards, are moved at an accelerated speed in the presence of a voltage so that they are uniformly distributed over the synthetic fibers. To this end, the target cloth is immersed in a separate inner vessel placed inside the reservoir which has a plurality of openings through which bubbles are generated at its lower portion. Afterwards, post-finishing is conducted, in which the synthetic fibers having nanosilver adsorbed thereon are ironed at 160 to 200°C. In addition, a dyeing process may be further conducted before the post-finishing. In the dyeing process, the nanosilver-adsorbed fiber may be dyed at about 130 "C for 3 to 5 hours with a mixture of acetic acid with a dye and a dispersant . An antibacterial fiber prepared according to the exemplary embodiment of the present invention includes nanosilver adsorbed thereon in an amount from 0.01 to 0.1 g per 100 g of the synthetic fibers. The antibacterial fiber is semi-permanently maintained washing durability, since the silver particles are in such a nano-scaled size that they show sufficient applicability. Test results for washing durability of the antibacterial fiber made of nanosilver-adsorbed fiber reveals that the nanosilver remained thereon even after 50 washes. In addition, the nanosilver is intensively adsorbed onto the surface of the synthetic fibers. Therefore, the antibacterial fiber according to the exemplary embodiment of the present invention may be a fundamental solution to the synthetic fiber's problems, that is, poor perspiration functionality and the generation of statistic electricity. [Mode for Invention] A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed as the limit of the present invention. <EXAMPLE 1> Step 1: Preparation of Solution of Nanosilver in Water First, as in a device for preparing an aqueous nanosilver solution, shown in FIG. 1, a water reservoir (101), provided with a water inlet valve (102) for introducing water thereinto and a water outlet valve (103) for draining water therefrom, having two Ag plates (104, 105) connected to a power source (DC+, DC-) , on its opposite sides, respectively, was filled with sufficient water to immerse the Ag plates completely. Next, 30,000 Volts was applied across the two Ag electrodes. The current flowing between the opposite electrodes was controlled to a desired value by moving up and down a circuit breaker (107) which was fitted into a groove (106) formed in a middle portion of the water reservoir to divide the water reservoir into two compartments. In the presence of the electric field, nanosilver was released into the water. The nono silver thus prepared was identified to have a size of 5 nm or less, with uniform particle distribution as measured using a scanning electron microscope (Model LEICA- STEROSCAN440) in FITI Testing & Research Institute of Korea (FIG. 2) . Step 2: Manufacture of Antibacterial Fiber Coated with nanosilver Synthetic fibers were washed with water and scoured at a maximum temperature of 125 °C so that the synthetic fibers were made clean and neat. Thereafter, the synthetic fibers were immersed in aqueous solution containing the nanosilver. Here, the temperature of the aqueous solution containing the nanosilver for the adsorption process was maintained at 230 °C under a pressure of about 2 atm, so that the nanosilver was thermally fixed on the surface of the synthetic fibers. In order to ensure the thermal fixation of the nanosilver onto the synthetic fibers, ultrasonication was conducted while bubbles were generated to accelerate the motion of the nanosilver. Afterwards, a dye and a dispersant were mixed in acetic acid and the synthetic fibers were dyed at 130 °C for 3 to 5 hours, followed by post-finishing in which the cloth was pressed at 200°C. <EXAMPLE 2> An antibacterial fiber was manufactured in a same manner to that of Example 1, with the exception that nanosilver having a size of 5 nm or less was prepared in the presence of 300,000 volts (DC+, DC-) in Step 1 of Example 1. <Comparative Example 1> The same procedure as in Example 1 was performed, with the exception that 220 volts (DC+, DC-) was applied in Step 1. As seen in FIG. 3, the nanosilver prepared in Comparative Example 1 was observed to aggregate together, with a non-uniform particle distribution under a SEM (model: LEICA-STEROSCAN440) in the FITI Testing & Research Institute of Korea, [industrial Applicability] As described hereinbefore, the present invention provides a method of mass producing nanosilver by applying a high voltage in water electrolysis and an antibacterial fiber having extensive nanosilver adsorbed thereon. Furthermore, the nanosilver adsorbed antibacterial fiber is free of the problems possessed by the general synthetic fibers, that is, poor perspiration functionality and high static electricity generation, and as well, shows potent suppression against a broad range of bacteria and microbes . Although the preferred embodimentsof the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
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