KR100536459B1 - Nanofibers web of cellulose acetate containing silver - Google Patents

Abstract

In the present invention, a nanofiber web of cellulose acetate containing silver is provided. Also provided is a filter for air purification and water treatment using the nanofiber web. The cellulose acetate nanofiber web may be prepared by dissolving a solution of cellulose acetate and silver nitrate in a solvent and then electrospinning.

The nanofiber web of the present invention performs air purification and water treatment by blocking the invasion of bacteria from outside air or water, and is advantageous for antibacterial action due to silver ions. Therefore, it can be used in various fields such as vehicle cabin air, commercial or residential filtration, water treatment in a water treatment plant, and household water purifier.

Description

Nanofiber web of cellulose acetate containing silver {NANOFIBERS WEB OF CELLULOSE ACETATE CONTAINING SILVER}

The present invention relates to a nanofiber web, and more particularly to a nanofiber web of silver-containing cellulose acetate (cellulose acetate), and a nanofiber web prepared by dissolving a solution of cellulose acetate and silver nitrate in a solvent and then electrospun will be.

In recent years, as the industrial development is highly developed, the increase of industrial pollution odor and water pollution has emerged as a serious environmental problem. Therefore, the suppression and prevention of various microorganisms present in the water quality and the air have become an urgent problem. In addition, there is a strong demand for the purification of low-contamination pollution under all environments including working and living environments of various industries.

In general, due to the pollution of the natural environment, indoor air, such as the living space, office or home where we live, is not clean, causing various problems. For example, nowadays there are many people who catch cold regardless of season, all due to the influence of environment where air is not clean. Also, when people living in the polluted environment of the city travel to the clean mountainous air, they can see the natural healing of mild respiratory diseases such as the cold, which shows how important clean air affects our human body. have. In addition, water can be a very important factor in our human body as long as it can last more than 10 days if we can only drink water without eating food. If such water is contaminated, our body can consume impurities or E. coli in it. Easily exposed to germs such as can be fatally affected.

Therefore, air purifiers for purifying contaminated air and water purifiers for water treatment of contaminated water have been widely recognized by recognizing these problems. Among these, air purifiers are usually forced to be sucked by the air intake fan by using a filter. Various impurities contained in the filtration are to be discharged again. Therefore, in the air purifier, a filter for filtering impurities in the air is a very important component. This is just like a filter that filters impurities in water in a water purifier is an important component.

The filter medium comprises one or more nanofiber web layers with substrate material in a mechanically stable filter structure. Together these layers provide efficiency for good filtration, high particle trapping, and minimum flow restriction when fluids (eg, gas or liquid) pass through the filter media. The substrate may be located in an upper stream, a lower stream or an inner layer in the fluid stream. Various industries have been of substantial interest in recent years for the use of filtration media for filtration, i.e. removal of unwanted particles from a fluid (eg gas or liquid).

Conventional filtration methods remove particulates from a fluid comprising an air stream or other gaseous stream or from a liquid stream (eg hydraulic fluid, lubricating oil, fuel, water stream or other fluid). Such filtration methods require the mechanical strength, chemical and physical stability of nanofiber webs and substrate materials.

Spinning techniques for producing ultra-fine nanofibers are known as conjugate spinning, melt blown spinning, flash spinnig, electrospinning, etc. Electrospinning is the only radiation method that can be produced.

In the spinning process, the fibers can form physical bonds between the fibers to interlock the fiber mats in an integrated layer. This material can then be made in the desired filter format (eg cartridge, flat disc, can, panel, bag and pouch). Within such a structure, the medium may be substantially corrugated, rolled, or otherwise disposed over the support structure.

The nanofiber webs described herein can be used as filters in a variety of applications, including, for example, dust collectors, air compressors, on-load and off-load engines, gas turbine systems, power generators (eg fuel cells), and the like. Can be.

In the manufacture of nanofiber filter media, a variety of materials have been used, including glass fibers, metals, ceramics and a wide range of polymeric compositions, and various techniques have been used to produce nanofibers with small diameters. One method includes passing the material through a fine capillary or opening as a molten material or into a solution and then evaporating it. The fibers can also be made using conventional 'spinning caps' in the production of synthetic fibers (eg nylon). In addition, electrostatic radiation is known. Such techniques include the use of trace needles, nozzles, capillaries or mobile emitters. These structures provide a liquid solution of polymer that is attracted to the recovery region by a high pressure electrostatic field. When the material is pulled out of the emitter and accelerated through the electrostatic area, the fibers become very thin and can form into the fiber structure by solvent evaporation. In the present invention, a method of preparing nanofibers using electrospinning was used.

When more demanding applications are anticipated for the filtration media, high temperatures of 100 to 250 ° F and up to 300 ° F, high humidity of 10 to 90%, high humidity of up to 100% RH, high flow rates of both gases and liquids, filtration of nanoparticles And a significantly improved material capable of withstanding the difficulty of removing both attrition and non-abrasion, reactive and non-reactive particulates from the fluid stream. Thus, there is a substantial need for filters and nanofiber materials that provide improved properties for filtering streams with high temperatures, high humidity, high flow rates and even particulate matter.

Cellulose acetate is widely used as various structures, for example, as a fiber for woven fabrics such as tobacco filter material and medical use, as a film, and as a structure (molded product) obtained by other injection molding or extrusion molding. Representative examples of cellulose acetate structures are fibers.

Such cellulose acetate fibers are currently manufactured as follows. First, a flake of cellulose acetate which is a raw material is dissolved in a solvent such as acetone to prepare a spinning solution of cellulose acetate. This spinning stock solution is supplied to a spinning nozzle apparatus and spun by a dry spinning method discharged in a high temperature atmosphere to obtain cellulose acetate fibers. It is also possible to use wet spinning instead of dry spinning.

Currently, we are exposed to many microorganisms such as bacteria and fungi that are harmful to humans in our daily living environment, and these bacteria and fungi are not only very diverse, but also widely distributed in the natural world such as soil, air, water and seawater. These microorganisms are damaging to humans and cause great problems both nationally and socially. For example, bacteria were detected in the O-157 bacteria wave, which became a major social problem in Japan in 1997, and various meats and ice creams in Korea. It is an example. Now, as the standard of living of Korean people improves, interest in life hygiene has been released. Therefore, unlike the past, we want to keep healthy life by preventing damage from harmful microorganisms (bacteria, mold, etc.) in advance.

As one of such measures, the company makes a strong preference for and purchases antimicrobial products when purchasing products, and various companies are investing heavily in research and development to launch antimicrobial products in order to meet consumer needs. It is true.

Ag is a semi-permanent compound that exerts antibacterial function by converting into sulfide attached to -SH group of protein cysteine, which constitutes bacteria, virus, fungi, etc. It is a very economical antibacterial agent. Ag has been neglected due to its high manufacturing cost compared to scientific and medical value. Inexpensive antibiotics have been exposed to many problems due to toxicity, side effects, and bacterial resistance. It is widely used as an antibiotic because its manufacturing cost is lower than that of general antibiotics. In addition, Ag has the ability to sterilize various pathogens and bacteria such as Escherichia coli, H. alveoli, and O-157. It can be used semi-permanently as an antimicrobial agent.

The ordinary filter only removes contaminants, so it removes fine bacteria and various contaminants, sterilizes and removes organics, and sterilizes and purifies the air to balance the cations and anions that are indispensable for the activity of life. Since they do not have the ability to adjust or decompose various toxins, air or water with a lot of pollutants is supplied to the inside, and oxygen is depleted in the human body, which causes the accumulation of undecomposed toxins and various diseases.

Accordingly, the present invention has been made to solve the above problems, and as a result of efforts to develop nanofibers that satisfies both effective air purification and water treatment, as well as excellent antibacterial effect, economic efficiency, nanofibers of cellulose acetate containing silver The present invention was completed by confirming that all of the above requirements can be satisfied.

An object of the present invention is to provide a nanofiber web that satisfies both air purification and water treatment functions, antibacterial and economical.

Another object of the present invention is to provide a nanofiber web of cellulose acetate containing silver.

It is another object of the present invention to provide a method for producing nanofibers and filters comprising the step of dissolving a cellulose acetate / silver nitrate solution in a solvent and then electrospinning.

Nanofibers according to the present invention comprise cellulose acetate containing silver as a component. As used herein, the term “nanofiber (or ultrafine fiber)” refers to a fiber having a nanometer diameter, and nanofibers having a diameter of 50 to 1000 nm can be easily manufactured by appropriately adjusting conditions during electrospinning. .

The nanofiber web of the present invention is a fiber assembly composed of nanofibers having a diameter of nanometers, which is flexible in nature, prevents accidental fine particles from passing through the nanofiber layer, and achieves substantial surface loading of the filtered particles. . In addition, particles comprising dust or other accidental particulates quickly form a dust cake on the nanofiber surface and maintain a high initial and overall efficiency of particulate removal. Even in the case of relatively fine contaminants with a particle size of about 0.01 to about 1 μm, the filter media comprising nanofibers has a very high dust capacity, which prevents the ingress of dust or bacteria from the outside, thus providing an air purifying function. To perform efficiently.

When the nanofibers of the present invention are used to perform an air purification function, an antimicrobial agent is added to sterilize a myriad of Escherichia coli, Staphylococcus aureus, Lung chirus, mold, Vibrio bacteria, bacteria, etc. As an antibacterial agent, it is economical and has an excellent antibacterial effect. ₃ ) A solution was used.

The cellulose acetate / silver nitrate solution is dissolved in a spinning solvent and then applied to an electrospinning apparatus to produce nanofibers. The choice of solvent is strict for several reasons. If the solvent dries too quickly, the fibers become flat and large in diameter. On the other hand, if the solvent dries too slowly, the solvent will dissolve the formed fibers again. Therefore, it is important to match the drying rate and fiber formation. As used herein, the term "spinning solvent" refers to a solvent that can be applied to electrospinning on the premise that a solution of cellulose acetate / silver nitrate should be dissolved. Examples thereof include a single solvent such as methylene chloride and acetone, or methylene chloride and methanol. Mixed solvents, such as these, can be used. Of these, acetone / water mixed solvent is most preferred as in the embodiment. At this time, the ratio of preferable water is 5-20 weight%. If the concentration is less than 5% by weight, silver nitrate, which is dissolved in acetone but insoluble in water, is decomposed, whereas if it exceeds 20% by weight, decomposed in cellulose acetate is water-soluble but insoluble in acetone. Because.

The electrospinning device that can be used for electrospinning is not particularly limited, and may be appropriately selected in consideration of the diameter of the nanofibers, the thickness of the nanofibers, and the like, and is capable of applying a high voltage (5-50 kV) that is generally used. Spinning devices can be widely used.

The diameter of the nanofibers (or ultrafine fibers) is within the range of 100-1,000 nm, preferably 200-700 nm by appropriately adjusting the concentration of cellulose acetate / silver nitrate solution, the type of electrospinning apparatus used, and the conditions during electrospinning. It can be adjusted appropriately. According to an embodiment of the present invention, the concentration of cellulose acetate is preferably 1 to 25% by weight, more preferably 5 to 15% by weight based on the acetone / water mixed solvent. This is because if the amount of solute is less than 1% by weight, the productivity is low because the amount of solute is too low, and if it exceeds 25% by weight, the viscosity is so high that electrospinning becomes difficult.

In addition, in the case of the silver nitrate solution used as a source of silver (Ag) ions, according to an embodiment of the present invention, ₃ ) The concentration of the solution was used 0.001-10% by weight, preferably 0.001-0.1% by weight, more preferably 0.01-0.05% by weight. If the content is less than 0.001% by weight relative to the amount of cellulose acetate, the antimicrobial activity of the antimicrobial agent is lowered. If the content exceeds 10% by weight, ammonia silver complex salt is formed upon addition to cellulose acetate, and precipitation occurs. This turns brown and causes a color change.

Further, the given voltage is preferably carried out in the range of 5-30 kV, more preferably 7-20 kV. The distance between the spinneret and the integrated plate is preferably 5-30 cm, more preferably 5-15 cm. However, the cellulose acetate / nitric acid solution concentration, the voltage and the distance between the spinneret and the integrated plate should be determined in consideration of the type of electrospinning apparatus, the required physical properties, the shape of the filter as a whole. The electrospun nanofibers formed web forms intertwined with each other.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples. Those skilled in the art to which the present invention pertains may make modifications or improvements with reference to the present specification without departing from the scope and object of the present invention.

* Antimicrobial degree: Determination of bacteria reduction rate by Keske 0693 (KS K 0693) method.

<Example 1>

0.3% by weight of silver nitrate in cellulose acetate ( ₃ ) The solution is mixed and dissolved in 13% by weight of acetone / water mixed solvent to prepare a 10% solution. Then, the distance from the spinneret tip to the integrated plate was 5 cm, and the voltage was fixed at 15 kV, followed by electrospinning to prepare a fiber assembly of cellulose acetate nanofibers. The prepared non-woven fabrics of ultrafine fiber yarns were immersed in an aqueous methanol solution for 10 minutes and then crystallized. After the crystallization was completed, methanol and water were removed to prepare an insoluble fiber aggregate. The fiber assembly prepared above was observed at a magnification of 5,000 times using a scanning electron microscope (Hidachi S-2350, Japan), and the results are shown in FIG. 2. As can be seen from the above results, the fiber assembly had a structure in which nanofibers having a uniform thickness of 250-450 nm were intertwined in a web form.

<Example 2>

0.1% by weight of silver nitrate in cellulose acetate ( ₃ ) The solution is mixed and dissolved in 13% by weight of acetone (acetone) / water mixed solvent to prepare a 10% solution was carried out in the same manner as in Example 1.

<Example 3>

1% by weight of silver nitrate in cellulose acetate ( ₃ ) The solution was mixed and dissolved in 13% by weight of acetone / water mixed solvent to prepare a 10% solution.

<Example 4>

0.01% by weight of silver nitrate in cellulose acetate ( ₃ ) The solution was mixed and dissolved in 13% by weight of acetone / water mixed solvent to prepare a 10% solution.

Comparative Example 1

Nanofibers were prepared using a solution in which a common cellulose acetate was dissolved in an acetone / water mixed solvent without adding a silver nitrate solution.

Table 1

    division    Example 1   Example 2   Example 3   Example 4   Comparative Example 1 Silver Nitrate Solution (wt%)     0.3     0.1      One     0.01      0 Average diameter (nm)     300     300    297     308    303 % Reduction     > 99    > 99   > 99    > 99   15.3

As shown in Table 1, the cellulose acetate nanofibers containing silver of the present invention have a high antibacterial property of 99% or more.

The fiber assembly made of nano-sized microfibers produced in the present invention is flexible in nature, prevents accidental fine particles from passing through the nanofiber layer, and has a very high dust capacity, thereby preventing dust from outside. It is possible to prevent the infiltration of bacteria can efficiently perform the air purification and water treatment functions.

In addition, silver nitrate which has antimicrobial activity to cellulose acetate ( ₃ ) When the nanofibers of the present invention are used to perform air purification and water treatment functions by adding a solution, since Ag has strong sterilization and antibacterial activity, such as air purification or water purification plant in underground air where air is not good, such as subway. It can be applied to water treatment, and can also be used in various parts of the medical industry such as wound dressings to heal wounds and abrasions.

1 is a schematic diagram showing an example of an electrospinning apparatus used for electrospinning.

FIG. 2 is a scanning electron micrograph of the cellulose acetate / silver nitrate solution prepared in Example 1 of the present invention in a 5,000 times magnification.

      Figure 3 is a transmission electron micrograph of the cellulose acetate / silver nitrate prepared in Example 1 of the present invention to observe a 200,000 times magnification of the ultrafine fiber yarn.

Claims (7)

Nanofiber web prepared by dissolving a solution of cellulose acetate and silver nitrate in a solvent and then electrospinning. The method of claim 1, Nanofiber web, characterized in that the composition ratio of the silver nitrate to cellulose acetate is 0.001 to 10% by weight. The method of claim 1, The concentration of cellulose acetate in an acetone / water mixed solvent is 1 to 25% by weight nanofiber web. The method of claim 1, The nanofiber web, characterized in that the solvent is acetone / water mixed solution. The method of claim 4, wherein The composition ratio of the acetone / water mixed solution is 95/5 to 80/20 nanofiber web, characterized in that. The filter of claim 1, wherein the cellulose acetate nanofibers are applied to an air purifier. The filter of claim 1, wherein the cellulose acetate nanofibers are applied to a water treatment apparatus.