TWI428411B - Transparent antimicrobial coating - Google Patents

Description

Transparent antibacterial coating

The present invention relates to an antimicrobial coating, and more particularly to a transparent antimicrobial coating.

In recent years, a large number of antibacterial products have been used in household goods to reduce the growth of bacteria to improve the quality of life and environmental sanitation.

The most widely used antibacterial material on the market is a silver-based antibacterial material, for example, a silver nanoparticle is dispersed in a plastic material to produce an antibacterial plastic container. However, the silver-based antibacterial material destroys the cell wall of the bacteria by the release of silver nanoparticles or silver ions, thereby achieving an antibacterial effect, and the persistence of the antibacterial effect is limited. Also, silver is a precious metal and expensive.

Further, although silver is mixed with a transparent plastic or the like, a transparent container having antibacterial properties or the like can be prepared, but the dispersion step of silver ions is complicated and easy to color, and silver ions are easily photoreduced or reacted with chloride ions to lose characteristics. . In order to improve these disadvantages, it is necessary to attach silver ions to silicone rubber, water-soluble glass, or zeolite.

In addition to silver, copper and zinc are also important metals constituting inorganic antibacterial compounds. However, since copper has a weak antibacterial activity against bacteria, it is only about 1/200 of silver. Therefore, antibacterial materials using metal ions of copper or zinc are generally not mainstream. However, the antibacterial materials of different metal ions have different effects on the bacteria caused by molds and the like. For mold, copper ions, nickel ions, and cobalt ions are strong, followed by zinc ions and silver ions. Moreover, it has been known since ancient times that a vase is placed in a copper plate to inhibit the occurrence of fungi or algae, and the flower is relatively long-lasting. Now, there are also shells for sewer water purification plants, ships, and submarines, and the method of sticking copper plates is used to prevent algae. Moreover, since ancient times, an aqueous solution of mixed copper sulfate and quicklime has been used to prevent the bacterial disease of grapes.

There are two kinds of antibacterial mechanisms of copper. The contact between copper ions and microorganisms in combination with microorganisms can reduce the activity and inhibit the metabolism of copper ions. The concentration of copper ions reaches 40ppb, and 50% of coliforms will not survive. The decrease in the number of bacteria is also affected by the concentration of copper ions. Another theory is to decompose organic matter in microorganisms by converting a part of oxygen in air or water into activated oxygen by the catalytic action of copper.

Copper can be used in the form of zeolite or silicone, as in silver. Compared with silver, copper has less deterioration due to the performance of light or chlorine. Therefore, it has high degree of freedom in use, and it can be metal copper itself, alloy, or An inorganic substance of copper, an organic copper compound, or a method of coordinating on a fiber or the like.

Copper-based antibacterial compound, similar to silver-based compounds, can be used for antibacterial and deodorant processing of plastics or fiber products. In addition, it can be widely used in water treatment by its excellent anti-mildew and anti-algae action. Anti-fouling of fishing nets or waterways, anti-corrosion of wood, de-wetting or anti-black mold of products around the flow table, or processing into antibacterial stainless steel, and applied to kitchens, food handling vehicles, conditioning equipment, etc.

It can be seen that copper-based antibacterial materials can be widely used. However, most of the copper-based antibacterial materials are copper metal, copper alloy, copper oxide, cuprous oxide, etc., and all absorb visible light. Coating the material on the surface of the substrate will affect the appearance of the substrate.

In recent years, information terminals such as touch panels have been used not only in smart mobile phones, but also in ticketing systems for mass transit such as convenience stores, railways, and MRT, or touches in hospitals, department stores, and the like. Information system. These touch panels are constantly being touched by most people, and they also virtually increase the path of infection. However, most of today's antibacterial coatings have color and cannot be applied to touch panels. If transparent antibacterial coatings are available, they can be applied not only to the above-mentioned terminals that are touched by most people, but also to glass bottom boats. The viewing glass of the sightseeing submarine can prevent the adhesion of microorganisms, or it can be applied to aquariums, general windows, antibacterial and mildewproof, etc., and can be used in many aspects.

Regarding the colorless transparency of the antibacterial material, Japanese Patent Laid-Open No. Hei 9-40502 discloses that an antimicrobially soluble glass having a characteristic particle diameter is added to a synthetic resin. However, the base material of the antibacterial material is plastic, and generally the wear resistance, weather resistance and light resistance of the plastic are poor. Therefore, the development of a coating material which is transparent and has a good antibacterial effect is a subject to be solved by the present invention.

In view of the above problems, an object of the present invention is to provide a transparent antibacterial coating, the main material compound being copper cerium oxide (SrCu ₂ O ₂ ) or represented by the chemical formula ABO ₂ , which is a compound having a cuprous iron ore structure and having good antibacterial properties. The effect, wherein A is selected from one of silver (Ag) or copper (Cu), and B is selected from the group consisting of aluminum (Al), strontium (Sc), chromium (Cr), yttrium (Y), iron (Fe), and indium ( In), one of gallium (Ga) and cobalt (Co).

Among them, the B metal ion of ABO ₂ is doped with divalent ions. The transparent antibacterial coating compound has a gap of at least 2.5 eV and a thickness of about 5 nm to 300 nm. The transparent antimicrobial coating requires a visible light transmission of at least greater than 50% and an ultraviolet transmittance of less than 10%.

The transparent antibacterial coating provided by the invention can maintain the appearance of the coated substrate and has good antibacterial properties. Since the antibacterial coating of the present invention is transparent in the visible light range, it can be widely applied to glass windows, glass containers, ceramic tiles, toiletries, etc., or to a viewing window of a touch panel, a glass bottom boat, and a sightseeing submarine. .

In order to make the above objects, features and advantages of the present invention more comprehensible, the following is a preferred embodiment of the method for preparing a transparent antibacterial coating and a coating according to the present invention, and with the accompanying drawings. The details are as follows.

The transparent antibacterial coating provided by the embodiment of the present invention comprises a compound having a cuprite structure. The compound may be copper ruthenium oxide (SrCu ₂ O ₂ ) or represented by the molecular formula ABO ₂ , and the structure of the later copper iron ore is as shown in FIG. 1 . Wherein, the A metal ion is selected from one of silver (Ag) or copper (Cu), and the B metal ion is selected from the group consisting of aluminum (Al), strontium (Sc), chromium (Cr), strontium (Y), iron (Fe), One of indium (In), gallium (Ga), and cobalt (Co).

The thickness of the antibacterial coating of the present invention is preferably about 5 nm to 300 nm, and the film thickness is less than 5 nm, the antibacterial effect is difficult to maintain for a long time, and the film thickness exceeding 300 nm reduces the light transmittance of the antibacterial film layer, and Affect the appearance of the coated object.

Since the antibacterial coating energy gap of the present invention is at least greater than 2.5 eV, when selecting materials with different energy gaps, and matching the thickness control of the coating, the visible light transmittance of the antibacterial coating of the present invention is at least greater than 50%, preferably More than 80%. When the antibacterial coating of the present invention is applied to a transparent substrate, the visible light transmittance of the transparent substrate is not greatly affected, and when applied to a non-transparent substrate, the appearance of the substrate can be maintained. Therefore, the antibacterial coating of the present invention can be widely applied to touch panels, glass bottom boats, viewing windows of sightseeing submarines, glass windows, glass containers, ceramic tiles, toiletries, and the like.

When the transparent antibacterial coating provided by the present invention is applied to a substrate, thermal evaporation, electron beam evaporation, molecular beam epitaxy, pulsed laser evaporation, sputtering, plasma spraying, or the like may be selected. A vacuum physical plating method such as a gas gel method, an electroless vapor deposition method, or a wet chemical method such as a chemical solution method, a spray pyrolysis method, or a gel-gel method. Regardless of the method used to form the coating on the substrate, it is sufficient that the coating compound can form a cuprite structure.

Among them, the wet method or the chemical vapor deposition method can form a film having a good gradient coverage, and therefore, the antibacterial coating of the present invention can be formed uniformly on the substrate in such a manner regardless of the surface shape of the substrate. Coating. Therefore, if the transparent antibacterial coating of the present invention is to be applied to an irregularly shaped artificial porcelain tooth or a magnet, it is preferred to use the above method.

In one embodiment of the invention, a clear antimicrobial coating is prepared using a chemical solution process. The metal salt is used as a raw material, and the precursor solution is dissolved in a suitable solvent, and then the coating is applied to the substrate by a wet method. The metal salt is a compound containing a B metal ion. For example: copper salt, chromium salt, aluminum salt, barium salt, indium salt, barium salt, gallium salt, cobalt salt and the like.

The copper salt is not particularly limited as long as it is a compound containing a copper metal ion, and examples thereof include copper acetate, copper nitrate, copper sulfate, copper chloride, cuprous chloride, etc., or bisacetylacetonate-based copper. An organic metal compound such as β-diketone copper or bishexafluoroacetic acid acetonyl copper.

The chromium salt may be selected from the group consisting of chromium acetate, chromium nitrate, chromium sulfate, chromium lactate, chromium oxalate or chromium chloride; the aluminum salt may be selected from aluminum acetate or aluminum nitrate; the barium salt may be selected from barium acetate or barium nitrate. Iron salt can be selected from iron acetate, iron nitrate, iron chloride, iron sulfate, and iron lactate. Other metal salts such as a cerium salt, an indium salt, a gallium salt, and a cobalt salt are not particularly limited as long as they respectively contain metal ions of cerium, indium, gallium, and cobalt.

The solvent used for uniformly dissolving the above metal salt may be selected from water, methanol, ethanol, propanol, butanol, diethyl ether, methyl ethyl ether, methyl butyl ether, ethylene glycol methyl ether, propylene glycol methyl ether, tetrahydrofuran. Wait. If the wettability of the coating and the substrate is considered, ethylene glycol methyl ether, ethanol, and propanol are preferably selected. In the examples of the present invention, the use of ethylene glycol methyl ether has the best effect. When considering safety and cost, water and ethanol are preferred.

In addition, in order to improve the stability of the metal ion in the precursor solution, additives such as a tackifier, a chelating agent, and a pH adjuster may be added.

After the preparation of the precursor solution, when a coating method is to be formed on the substrate by the wet method, spin coating, dip coating, spray coating, screen printing, brush coating, or the like may be selected, and is not particularly limited. Among them, the antibacterial coating is applied to the substrate by spin coating, so that the coating has better uniformity.

After the coating is applied to the substrate by wet coating, the steps of drying, thermal cracking, and reaction crystallization are sequentially performed.

Wherein, the drying step is performed by placing the substrate on a heating plate or in an oven, and the drying temperature is preferably in the range of 80 ° C to 300 ° C, but it is preferably controlled at 120 ° C to 250 ° C to obtain a better effect. If the drying temperature is too low, the drying time will be too long, and if the wettability of the solution is not good, the coating will be uneven, and if the drying temperature is too high, the coating will be easily cracked.

In the subsequent thermal cracking step, the substrate can also be placed on a heating plate or in an oven, and the thermal cracking temperature is preferably in the range of 250 ° C to 500 ° C. In the embodiment of the present invention, the thermal cracking temperature is controlled at 300 ° C to More preferably in the range of 450 ° C. When the thermal cracking temperature is lower than 250 ° C, the cracking reaction is incomplete, and when the precursor solution is applied again, the solvent of the precursor solution dissolves the compound which is not completely cracked in the previous coating layer, and The film quality is deteriorated.

Finally, the crystallization step is carried out, and the substrate is placed in a heating device such as a heating plate, a tubular high temperature furnace, or a rapid annealing furnace. The crystallization temperature depends on the composition of the coating layer and the reaction atmosphere. For example, the crystallization temperature of alumina copper (CuAlO ₂ ) in air needs to reach at least 900 ° C to obtain the pure phase of the copper-copper iron structure, and the chromium oxide. Copper (CuCrO ₂ ) only needs to reach 700 ° C to obtain a pure phase of copper-copper iron ore structure. However, if heated in a passive gas atmosphere or in a reducing atmosphere, alumina copper (CuAlO ₂ ) and copper chromium oxide (CuCrO ₂ ) can be crystallized at a relatively low temperature. However, it is preferred that the crystallization temperature range is controlled to be about 450 ° C to 1000 ° C, but it is preferably controlled at about 500 ° C to 800 ° C, and further preferably the temperature range is controlled from 600 ° C to 700 ° C.

The method for preparing a transparent antibacterial coating by the chemical solution method of the present invention is specifically illustrated by the following examples.

First, a precursor solution of aluminum oxide copper (CuAlO ₂ ) or copper chromium oxide (CuCrO ₂ ) is prepared. A copper scale: aluminum nitrate (or chromium acetate): ethanolamine = 1:1: 4 molar ratio scale. In the preparation, the copper acetate and ethanolamine are first dissolved in ethylene glycol methyl ether, and the mixture is heated and stirred for 2 hours, and then aluminum nitrate (or chromium acetate) is added, and the mixture is stirred for 12 hours, and then the solvent is added to a specific amount to prepare alumina copper ( A precursor solution of CuAlO ₂ ) or chromium oxide copper (CuCrO ₂ ).

Next, alumina copper (CuAlO ₂ ) or copper chromium oxide (CuCrO ₂ ) is applied to a glass substrate or an alumina substrate by a spin coater. Spin coating on a glass substrate for 15 seconds at 4000 rpm. After each spin coating, the glass substrate is placed on a hot plate, heated to about 150 ° C for 4 minutes, and then pre-annealed in a tubular furnace for thermal cracking, first heating the glass substrate to about 400 ° C. After holding the temperature for 5 minutes, cool for another 3 minutes. In another embodiment, aluminum oxide copper (CuAlO ₂ ) or copper chromium oxide (CuCrO ₂ ) is applied to the substrate using a dip coating process.

After the steps of coating, drying, and thermal cracking are repeated five times, the glass substrate is placed in a tubular furnace to perform a crystallization step. In the embodiment of the present invention, annealing is performed at 900 ° C for 30 minutes in an air atmosphere. An aluminum oxide copper (CuAlO ₂ ) film was annealed at 700 ° C for 30 minutes to obtain a chromium chromium copper (CuCrO ₂ ) film.

When the transparent antibacterial coating of the present invention is formed on a substrate by using a physical vapor deposition method such as thermal evaporation, electron beam evaporation, molecular beam epitaxy, pulsed laser vapor deposition, or sputtering, The compound ABO ₂ sintered body having a cuprous iron ore structure may be used as a target, or a plurality of pure metal targets or oxide targets may be used for multi-source evaporation, and a suitable gas may be introduced to form the transparent antibacterial coating of the present invention. Floor. The coating prepared by the physical vacuum method can be further annealed in various atmospheres to enhance the properties of the antibacterial coating such as crystallinity, adhesion, and transparency.

In a preferred embodiment of the present invention, the copper oxide powder is mixed with chromium oxide or aluminum oxide powder at a molar ratio of 2:1, and then stabilized with high-purity alcohol and a diameter of 1 mm. The zirconia grinding balls were mixed in a PE plastic tank with a solid content of about 30 wt.%, and then subjected to wet ball milling for 24 hours using a planetary motion mixer.

The ball milled powder was dried in an oven at 70 ° C for 36 hours, and the dried powder was ground using a high-density agate mortar. After grinding, the powder was placed in an alumina crucible and placed in a high-temperature furnace at 1200 ° C. hour. After that, the powder is reground and sieved, and the obtained powder is pressed into a round ingot having a diameter of 2 Torr by a manual forming machine, and then placed in a high temperature furnace and sintered at 1250 ° C for 8 hours, which is copper chromium oxide (CuCrO ₂ ) or oxidized. Aluminum copper (CuAlO ₂ ) or 2 吋 target.

The target material and a glass substrate or an alumina substrate are placed in a sputtering machine, and an oxygen-argon mixed gas is used for RF magnetron sputtering to form chromium chromium copper (CuCrO ₂ ) or alumina on a glass substrate or an alumina substrate. Copper (CuAlO ₂ ) film.

In order to test the antibacterial ability of the transparent antibacterial coating of the present invention and adhesion to a substrate, the inventors prepared a copper film on a glass substrate by sputtering, and prepared copper oxide (CuO) on a glass substrate by a chemical solution method. The film was used as a comparative example. Wherein, when preparing a copper oxide (CuO) film on a glass substrate by a chemical solution method, the copper acetate and ethanolamine are still weighed in a ratio of 1:4, and copper acetate and ethanolamine are dissolved in ethylene glycol methyl ether, and the mixture is heated and stirred. After 12 hours, the solvent was added to a specific amount to prepare a precursor solution of CuO. The conditions of the spin coating, drying, and thermal cracking steps are the same as those for preparing a chromium chromium copper (CuCrO ₂ ) or aluminum oxide copper (CuAlO ₂ ) coating. Finally, when the substrate was placed in a tubular furnace for crystallization, it was annealed at 600 ° C for 30 minutes to obtain a CuO film.

Further, a commercially available antibacterial stainless steel having a thickness of 0.3 mm, a pure copper sheet, and a glass substrate of the substrate to be coated were cut to a length of 2 cm × 2 cm, and various tests were carried out in the same manner as in the examples of the present invention.

When the antibacterial test was carried out, the antibacterial coatings obtained in the examples and the comparative examples were tested for the antibacterial ability, the adhesion (tape test) and the light transmittance of the coating.

Antibacterial test

In the present invention, the measured antibacterial properties are shown in Table 1 according to the JIS Z 2801 antibacterial test method. Among them, the antibacterial rate (R) = (control group - sample group) / control group × 100%, with the antibacterial rate of 12 hours as the evaluation standard, the antibacterial rate of more than 90% was evaluated as ○, and the antibacterial rate was less than 90%. Those above 50% were evaluated as △, and those with an antibacterial rate below 50% were evaluated as ×. Fig. 2 shows a photograph when the plate test is counted. Fig. 3 is a view showing the antibacterial ability of the examples and comparative examples.

Referring to Fig. 4, a photograph of an aluminum oxide copper (CuAlO ₂ ) or copper chrome copper (CuCrO ₂ ) antibacterial coating layer applied to a glass substrate or an alumina substrate according to an embodiment of the present invention is shown. The inventive examples 1 to 4 and the comparative examples 1 and 2 are placed on the background 30, and the antibacterial coatings of aluminum oxide (CuAlO ₂ ) and copper chromium (CuCrO ₂ ) can be obviously compared in the first and second embodiments of the present invention. The light transmittance on the glass substrate is still high, which proves that the transparent antibacterial coating of the present invention can maintain the appearance of the coated substrate in addition to the antibacterial ability as much as the conventionally used copper coating.

2. Determination of adhesion (tape test)

For the measurement of the adhesion (tape test), the antibacterial coatings obtained in the examples and the comparative examples were adhered to a surface of a 1 cm × 1 cm test piece by a 3 M scotch tape for 1 minute, and then peeled off to observe whether or not an antibacterial coating was observed. The peeling was judged, and the adhesion between the coating and the material was judged, and it was judged as ○ when there was no peeling at all, and it was judged by the naked eye that the peeling was judged to be ×. The results are shown in Table 1.

3. Light penetration test

The antibacterial coatings obtained in the examples and the comparative examples were measured on a UV-Vis spectrometer (JASCO V630) using a glass substrate as a blank test piece, and the results of light transmittance at 550 nm are shown in Table 1. The measured penetration rate is shown in Table 1.

From the results of Table 1, it is understood that the transparent antibacterial coating provided by the present invention not only has good antibacterial properties, but also has high light transmittance. According to the tape adhesion test, it was found that the adhesion of the coating of the present invention to a glass substrate is better than that of copper oxide and copper used in the prior art. Therefore, it can be widely used in various panels, in particular, a viewing panel of a touch panel, a sightseeing submarine and a glass bottom boat, an antibacterial mildew of a general glass, an aquarium, a vase, or various ceramics.

Further, the antibacterial coating of the present invention has a UV-cut function because its energy gap is about 3.1 eV and the ultraviolet transmittance is less than 10%. On the other hand, since the transparent antibacterial coating of the present invention itself has electrical conductivity, the defogging glass can be formed by connecting electrodes. Therefore, the transparent antibacterial coating of the present invention can impart high light transmittance, good antibacterial property, ultraviolet shielding property and antifogging property to the glass at the same time.

The present invention has been described above by way of a preferred example, but it is not intended to limit the spirit of the invention and the inventive subject matter. Those who are familiar with the technology can easily understand and utilize other components or methods to produce the same effect. Modifications made without departing from the spirit and scope of the invention are intended to be included within the scope of the appended claims.

A, B. . . Metal ion

O. . . Oxygen ion

20~26. . . Embodiment 1 to Embodiment 7

27~29. . . Comparative example 1~3

200. . . bacterial

Figure 1 is a schematic view showing the structure of a cuprous iron type antibacterial compound of the present invention;

Figure 2 is a photograph showing the results of the antibacterial test of the examples and comparative examples of the present invention;

Figure 3 is a graph showing the antibacterial properties of the examples and comparative examples of the present invention;

Fig. 4 is a photograph showing an application of an aluminum oxide copper (CuAlO ₂ ) or chromium oxide copper (CuCrO ₂ ) antibacterial coating on a glass substrate or an alumina substrate according to an embodiment of the present invention.

20~26. . . Embodiment 1 to Embodiment 7

27~29. . . Comparative example 1~3

200. . . bacterial

Claims (4)

A transparent antibacterial coating comprising a compound represented by copper ruthenium oxide (SrCu ₂ O ₂ ) or represented by the chemical formula ABO ₂ , wherein the metal ion copper (Cu), the metal ion of B is selected from aluminum (Al), strontium (Sc), chromium (Cr), yttrium (Y), iron (Fe), indium (In), gallium (Ga), cobalt (Co), and the transparent antibacterial coating compound The energy gap is at least greater than 2.5 eV, such that the transparent antimicrobial coating has a visible light transmission of at least greater than 50% and an ultraviolet transmittance of less than 10%. The transparent antibacterial coating according to claim 1, wherein the B metal ion of ABO ₂ is doped with divalent ions. The transparent antibacterial coating of claim 1, wherein the transparent antibacterial coating has a thickness of about 5 nm to 300 nm. The transparent antibacterial coating according to claim 1, wherein the B metal ion is selected from one of aluminum (Al), chromium (Cr) or yttrium (Y), and the transparent antibacterial coating has an energy gap larger than 3.0eV, visible light transmittance of at least 80%, for touch panels, sightseeing submarines and glass bottom boat viewing windows, general glass, aquarium, vase or ceramic substrate, to achieve anti-mildew and antibacterial effects.