KR100422568B1 - Production of inorganic antimicrobial agent having high antibacterial potency suitable for manufacture of antimicrobial resin as well as improved color and low toxicity by treating waste supported silver catalyst - Google Patents

Abstract

PURPOSE: Provided is a method of making an inorganic antimicrobial agent by treating a waste supported silver catalyst, wherein the silver is supported on porous alumina, in three stages including a chlorination reaction, calcination, grinding and classification. The product has high antibacterial potency suitable for the manufacture of antimicrobial resin as well as improved color and low toxicity. CONSTITUTION: A waste supported silver catalyst, wherein the silver is supported on porous alumina for production of ethylene oxide is treated in three stages including a negative ion introduction reaction, calcination, grinding and classification to produce an inorganic antimicrobial agent. In the negative ion introduction reaction, the waste supported silver catalyst and negative ion are introduced into a reactor and then reacted at 0 to 50deg.C at 1 to 10atm. The calcination is performed at 100 to 300deg.C for 1 to 3hr in air, the classification is achieved by grinding the catalyst and separating particles having an average particle size of 0.05 to 20μm. The negative ion is one or more selected from chlorine, nitrogen, phosphoric acid, hydrogen oxide, ammonium, amine or organic acid groups.

Description

Manufacturing method of inorganic antibacterial agent using silver catalyst catalyst waste

The present invention relates to a method for producing an inorganic antimicrobial compound having good stability and non-toxic effect on bacteria and fungi by reprocessing silver supported catalyst waste for producing ethylene oxide, and more particularly, silver is added to a porous inorganic carrier. The present invention relates to a method for producing an inorganic antimicrobial compound having high antibacterial activity and low toxicity, which can be reprocessed evenly supported silver supported catalyst.

The catalyst for producing ethylene oxide by gas phase contact partial oxidation of ethylene and molecular oxygen is in a form in which silver is evenly supported on a porous inorganic carrier, and the silver supported catalyst has been used for a long time (about 2 to 5 years). When used for), the yield and selectivity are lowered, making it solid with a new catalyst. The waste catalyst generated for this reason contains silver, which is a noble metal (3 to 16%), and the silver is recovered or disposed of in case of high recovery cost. However, this conventional method is not good because it can cause environmental problems.

Antimicrobials for antimicrobial resins used to improve the problems caused by bacteria and fungi can be generally divided into organic and inorganic antimicrobials. Inorganic antimicrobial agent is an even dispersion of antibacterial metals such as silver, copper, zinc and the like on a carrier such as zeolite, silica, alumina, zirconium phosphate, etc. It is possible to ensure a lasting effect than the organic type antimicrobial agent, and has been widely used in the production of antimicrobial resin compositions because of high heat resistance and high stability.

Commercially produced inorganic antimicrobial agents include at least one antimicrobial metal selected from silver, copper, zinc, mercury, tin, lead, bismuth, cadmium, chromium, palladium, and the like, such as natural zeolite, synthetic zeolite, silica, alumina, zirconium phosphate, and the like. It is supported by the ion exchange method or the wet method. Among these inorganic antimicrobials, the inorganic antimicrobial agent containing silver as the main component is not toxic, so it is most used as an antimicrobial agent used in moldings that can come into contact with the human body, but the price is very high.

In the present invention, the purpose of the present invention is to find that the waste catalyst for producing ethylene oxide has the same composition as an inorganic antimicrobial agent, and to provide a method of reprocessing the inorganic antimicrobial agent for antimicrobial resin having a high antimicrobial activity and a low toxicity which is a function to be used as an antimicrobial agent as a raw material. .

That is, an object of the present invention is to prepare an inorganic antimicrobial compound, characterized in that in the method for producing an inorganic antimicrobial agent for antimicrobial resin, by using a silver supported catalyst waste for the production of ethylene oxide to prepare an inorganic antimicrobial agent having high antibacterial activity and low toxicity. To provide a way.

It is known that the only catalyst used in the oxidation process for converting ethylene into ethylene oxide by catalytic synthesis is silver which is supported on a porous inorganic carrier. Recently, however, a catalyst prepared to obtain high yield of ethylene oxide is a porous carrier by adding silver (0.5-20%) as the main catalyst and alkali metals and alkaline earth metals (less than 1%) as reaction promoters and activators. It is generally molded to have a suitable size and shape by supporting it. The catalyst for producing ethylene oxide is difficult to use any more because the activity of the catalyst is reduced by various contaminants during use, and the waste catalyst generated in such a case varies depending on the history of use.

The catalyst for producing ethylene oxide having 0.5 to 20% by weight of silver finely distributed in the porous carrier may be used as a direct antimicrobial agent due to similar components to the inorganic antimicrobial agent, but the antimicrobial activity is low, the color is blackish brown, and it is harmful to the human body. The catalyst for preparing ethylene oxide itself is difficult to use as an antimicrobial agent because it may contain a trace amount of volatiles.

Therefore, in the present invention, in order to improve this weakness, 3 of the ignition reaction step to increase the antimicrobial power and color, the calcination step to remove volatiles that may remain in the waste catalyst, the grinding step to have a particle distribution suitable for the antimicrobial agent By the step treatment, a method for producing an inorganic antimicrobial agent having excellent antibacterial activity and whiteness using a silver supported waste catalyst is provided. The order of the steps may be changed in some cases.

In the method of the present invention, a silver-based antimicrobial activity mechanism (Mechanism) was used to increase the antimicrobial activity. According to the antimicrobial activity mechanism of the silver-based antimicrobial agent proposed so far, the higher the elution amount of silver when accepting elution, and the higher the ionicity of silver when accepting active oxygen, the higher the antimicrobial activity. In general, since the elution amount of silver can be increased by increasing the ionicity of silver, the ionicity of silver must be increased to increase the antimicrobial activity. As a method of increasing the ionicity of silver, the method of substituting metal silver with a chlorine group, a nitric acid group, a phosphoric acid group, a hydroxyl group, an ammonium group, an amine group, or an organic acid group is mentioned. However, the method of introducing a chlorine group is most preferable to introduce a chlorine group because it can improve the antibacterial activity and whiteness at the same time.

In general, the chlorination method uses a wet method of complexing silver metal with hydrochloric acid, but this method uses a method of directly injecting chlorine into the waste catalyst because a large amount of wastewater is generated and the control of the reaction is difficult. . Controlling the amount of chlorination reaction can be obtained by controlling the temperature and pressure in the reactor, the operating temperature was O ℃ to 50 ℃, the reaction pressure is preferably used 1 to 10 atm, but preferably the reaction temperature By adjusting the reaction pressure at 20 ℃ to 40 ℃ and the pressure of 1 to 4 atm can be adjusted to 1% to 100% of the rate of silver contained in the carrier to silver chloride, but three antimicrobial properties of antibacterial activity, color and change over time The preferred range to satisfy is 10% to 90%.

In order to remove a small amount of water and organic matter which may remain on the unreacted chlorine and the catalyst in the chlorination reaction, it is preferable to bake for 1 hour to 3 hours in air at 100 ℃ to 300 ℃. Through the chlorination and calcining process, a neutral inorganic compound containing almost no volatile substance having a pH value of 6 to 8, measured in 5% slurry within 0.1% of ignition residue, can be obtained.

The final step for preparing the inorganic antimicrobial agent is the grinding and classification process for maintaining the high antibacterial power by uniformly dispersing the neutral inorganic compound obtained in the above process in the medium used. In order to maintain high antimicrobial activity and to disperse with the medium, it is recommended that the average particle size be 0.05 to 20 microns, but preferably 0.1 micron to 1 micron for antibacterial fibers and 1 micron to 10 microns for one reaction. It is good to have a particle size.

The stability (toxicity) of the inorganic antimicrobial agent prepared from the silver supported waste catalyst of the present invention prepared by such a method was evaluated by acute oral toxicity, AMES test and heavy metal dissolution test items. The acute oral toxicity test was conducted in accordance with the "Medical Stability Test Management Criteria" of the Ministry of Health and Social Affairs No. 87-80 (October 29, 1987). According to the "Toxicity Test Standards for Drugs," it is evaluated as the result of mortality, general symptoms, weight change and autopsy findings by oral administration to each of the five male and female rats of SD system at a fixed dose. The AMES test, proposed by Professor Ames of the University of California, USA, is used as a criterion for mutagenicity, carcinogenicity, and stability in the US Environmental Protection Agency and the Labor Department in Japan. The test is assessed by monitoring the development of mutations by administering a constant concentration to Salmonella typhimurium TA100 and Salmonella typhimurium TA98 bacteria.

The antimicrobial properties of the antimicrobial agent can be estimated as the minimum growth inhibitory concentration (MIC) for various general bacteria, yeasts and fungi. The minimum growth inhibitory concentration (MIC) is prescribed by Muller-Hinton Broth, and then inoculated with a certain amount of microbial solution, followed by incubation in a shaking incubator at 35 ° C for 24 hours, followed by visual growth. Determine the minimum concentration to inhibit the growth of bacteria.

Among the properties of antimicrobials, the next most important property is color. If the color of the antimicrobial is colorless, it is most desirable because it can make a variety of products of different colors. The inorganic antimicrobial agent synthesized by the present method may increase the whiteness as the content of silver chloride, an ionic silver salt, increases, but there is a disadvantage in that discoloration occurs due to sunlight. However, since the discoloration by sunlight does not change the performance of the antimicrobial activity, it can be used in the antimicrobial composition by adjusting the ratio of silver chloride according to the use (indoor and outdoor).

The antimicrobial agent prepared according to the present invention is provided for solving problems caused by general bacteria, yeasts and fungi in the antimicrobial woven fabric, paint field, construction field, papermaking field and the like.

The antimicrobial resin field is prepared by impregnating the above-mentioned antimicrobial agent with a resin or coating the surface of such a resin to impart antimicrobial and antifungal properties to the resin. The resin is polyethylene, polypropylene, polyvinyl chloride, polystyrene, ABS resin, polyester resin, nylon, polyamide, polyvinyl alcohol, polyvinylacetate, polycarbonate, polyurethane, epoxy resin, rayon resin, natural or synthetic rubber, etc. It includes.

In the paint field, the antimicrobial agent of the present invention is directly incorporated into or coated with a lipophilic paint lacquer, varnish and alkyd resin type, vinyl resin type, acrylic resin type, epoxy resin type, urethane resin type, phenol resin type solution or powder type paint. Coating on the surface of the film can impart antimicrobial and antifungal properties.

In the construction field, antimicrobial and antifungal properties may be imparted by incorporating the antimicrobial agent of the present invention into a material of various building parts such as walls, ceiling finishes, building or playground sand, tiles, and the like.

Inorganic antimicrobial agents of the present invention are used in all areas in which microorganisms should be suppressed in addition to the above-described fields, such as water cleaners, antibacterial drugs for various cooling waters, and the like for use in fresh tissue paper, paper packaging paper, corrugated paper, and the like.

The antimicrobial agent and the content used in the antimicrobial composition are determined in the concentration range of 10 to 100 times the minimum inhibitory rate (MIC) of the antimicrobial agent itself, and the content of the antimicrobial agent used is 0.01% by weight to 10% by weight, preferably 0.5% by weight. Suitably up to 5% by weight.

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

Example 1 <Preparation of Antimicrobial Agents>

As a raw material used, a new catalyst (Scientific design co., Inc. (US), trade name: Syndox-845) and a waste catalyst used for 3.2 years were used as raw materials for the production of antimicrobial agents. The new catalyst is molded into a Φ10 × 15 mm cylinder by supporting porous gamma alumina with 8.5% silver (Ag) and less than 1% of other alkali metals. The waste catalyst is a catalyst which is carried out after 3.2 years of use in a commercial plant by supporting the new catalyst in a reactor, and is a catalyst that is no longer used for ethylene oxide production. The new and spent catalysts were stored in plastic bags for 4 years for new catalysts and 8 months for spent catalysts in cold and dark places.

Reprocessing with an antimicrobial agent was carried out by grinding first and chlorination and firing later. First, the cylindrical catalyst was ground to an average particle size of 2 to 3 µm using a glass mill hammer mill. 300 g of the pulverized catalyst was fixed at 700-1000 rpm in a reactor equipped with a silver gauge, a pressure gauge, and a stirrer, and a constant amount (10 g) of chlorine was injected, and then the reaction pressure and temperature were adjusted and stirred for 30 minutes. After the reaction was completed (after 30 minutes), the inside of the reactor was sufficiently expanded with nitrogen, and then taken out and calcined at 150 ° C. in air for 3 hours. The silver in this sample is changed from silver (Ag) on the metal to silver salt (AgCl) on the ionic phase. This was confirmed using XRD (X-ray diffraction analysis), and composition analysis is not dissolved in 1: 1 nitric acid when silver is changed to silver chloride, so first dissolve the metallic silver with 1: 1 nitric acid and analyze it by the concentration of silver (Ag). The rest were defined as ionic silver salts contained in silver chloride.

First, according to Table 1, as the reaction temperature was lowered and the pressure was increased, the metallic silver was converted into silver chloride, an ionic silver salt. The XRD graph of the sample for confirming the above result is shown in FIG. 1 compared with the new catalyst used as a raw material. As the new catalyst contained metallic silver in the alumina carrier, only the diffraction peaks of the metallic silver (Ag) and the carrier appeared, but the samples prepared by the manufacturing method of the present invention were not only silver (Ag) but also silver chloride (AgCl). Coexist together.

Table 1

Example 2 <Physical Properties and Antibacterial Activity of Prepared Antibacterials>

As a representative physical property of the sample synthesized as described above, the whiteness (WI) was measured using a pH (pH) and a Hunter Colorimeter (5%) of the slurry, and the antimicrobial activity of E. Coli ATCC 25922 as the representative strain. The minimum growth inhibition concentration (MIC) was measured and shown in Tables 1 and 2. At this time, as a comparative data, the new catalyst was ground and measured in the same manner as in Example 1 only.

According to FIG. 2, the antimicrobial activity and whiteness could be increased by changing the metallic silver to silver chloride in the preparation method of Example 1 in the new catalyst having almost no antimicrobial activity. It can be seen that increases.

Example 3 <antibacterial activity test for each strain>

For the samples (1) and (4), the minimum inhibitory concentration (MIC) of the general bacteria and yeast was measured and shown in Table 2. As shown in Table 2, it was found that the antimicrobial agent prepared by Example 1 did not act only on specific bacteria but was effective against a wide range of strains.

TABLE 2

Example 4 <Toxicity Test>

In the toxicity test, the results of acute oral toxicity, AMES test, and heavy metal dissolution test were performed on the sample (1). Acute oral toxicity is in accordance with the "Drug Safety Test Management Standards" of the Ministry of Health and Social Affairs 87-80 (October 29, 1987) .The test method is "Drugs" of No. 94-3 (April 14, 1994) of the National Institute of Health and Safety. To observe the mortality, general symptoms, weight change and autopsy findings by five oral doses of 0 mg / kg and 5000 mg / kg, respectively, in male and female rats of SD strains according to the Toxicity Criteria. No dead animals, general symptoms, body weight changes and necropsy findings due to administration of the samples prepared by the method of the present invention were observed. Therefore, the LD ₆₀ value of the sample (1) prepared by the method of the present invention could be classified as a non-toxic compound of more than 5000mg / kg. The AMES test, proposed by Professor Ames of the University of California, USA, as a criterion for mutagenicity, carcinogenicity and stability in the US Environmental Protection Agency and the Labor Department in Japan, is the Salmonella typhimurium TA100 and Salmonella. Typhimurium TA98 (Salmonella typhimurium TA98) bacteria were evaluated by observing the occurrence of mutations by introducing a certain concentration of samples. Sample (1) prepared by the method of the present invention was diluted with DMSO (dimethyl sulfoxide) to a concentration of 500ug / ml, 1,000ug / ml, 10,000ug / ml, 50,000ug / ml and 2-nitrofluorene Mutation was observed using the solution dissolved in DMSO to 20 mg / ml as a control bacterium, but no mutation occurred in the entire concentration range used. In other words, the above sample (1) was found to be negative for the mutation. Therefore, the above sample (1) shows that LD ₆₀ value is 5000mg / kg in acute oral toxicity, indicating that it is nontoxic when LD ₆₀ of saline is 4000mg / kg. It can be seen that it is an antimicrobial compound.

Example 5 <Application to Antibacterial Resin>

The antimicrobial and antifungal activity of the antimicrobial agent 1 prepared by the method of Example 1 was added to the resin by kneading LDPE (manufactured by Samsung Synthetic Chemical, 220S) at a ratio of 0.2 to 1.0% by weight. .

The antimicrobial activity was analyzed by the shake flask (Shaks Flask method) method similar to the MIC of the antimicrobial agent itself (Method: KS-K0693 (see the antimicrobial test method of the fabric)) by the reduction rate. In this method, put 0.7g to 1g of sample in a flask with a surface area of 60cm ³ , shake the test bacteria with inoculation 150 times / min for 24 hours at 25 ° C, and divide the initial bacteria count after the shaking before the shaking. Phosphorus reduction rate was set as an evaluation standard. As shown in Table 3, the number of bacteria was increased in the untreated sample, but by reducing the antibacterial agent prepared by the method of the present invention with 0.3% by weight of the resin, the bacterial reduction rate was 80% or more with respect to general bacteria. Therefore, these resins are effective for E. coli (IFO 3972) and Staphylococcus aureus (IFO 12732), so they are not only suitable for general kitchen items such as sanitary cutting boards and water bottles, but also the most common bacteria found in hospitals. Also effective for), it is also suitable for hospital supplies.

Antifungal properties are shown in Table 4 by the ASTM G21 method using a mixed strain and ringworm of ASTM G21. As shown in Table 4, it was shown that the growth of the mixed strain and ringworm bacteria was suppressed compared to the untreated sample by mixing 1.0 wt% of the antimicrobial agent prepared by the method of the present invention with the resin. Therefore, the product prescribed in the antimicrobial agent prepared in the resin of the present invention is effective against the mold, so it can be used in sanitary and construction supplies such as shoe soles that are contaminated from the mold.

TABLE 3

Table 4

1 is an X-ray diffraction graph of an inorganic antimicrobial agent and a catalyst which is a raw material prepared by the preparation method of the present invention.

2 is a graph showing the minimum growth inhibitory concentration (MIC) and the whiteness according to the change in the composition of chlorine, the more the chlorine contained, the minimum growth inhibitory concentration decreases (antibacterial activity increases) and the whiteness increases.

Claims (4)

The silver supported waste catalyst for producing ethylene oxide, in which silver is supported on porous alumina, is treated in three stages: anion introduction reaction, calcination, pulverization, and classification. The reaction is carried out at ~ 50 ℃ and reaction pressure 1 ~ 10 atm, the firing is carried out in the air at 100 ~ 300 ℃ for 1 to 3 hours, the grinding and classification is average of 0.05 to 20 microns after grinding the catalyst Method for producing an inorganic antimicrobial agent, characterized in that performed by classifying particles having a particle size. The method of claim 1, wherein the anion used in the anion introduction reaction is at least one anion selected from chlorine, nitric acid, phosphoric acid, hydroxyl, ammonium, amine or organic acid groups. The method for preparing an inorganic antibacterial agent according to claim 2, wherein the content of chlorine ions relative to the total silver is 0.5 wt% to 24.7 wt% in introducing chlorine groups. The method of claim 1, wherein the ionic phase silver contained in the silver chloride has 10% to 90% by weight of the total silver.