Antimicrobial communication board

Anti-microbial communication board

[0001] The present invention relates to an interactive (or otherwise) enameled (enamelled) visual communication board (communication board), whether it is possible to use, for example, a dry-erasable felt-tip pen (felt-tip pen) in its The erasable board for writing on it, or the colored chalk board or the like that can be written with chalk.

[0002] Communication boards in offices and classrooms are used by many people every day, which makes the boards potentially dangerous for the spread of microorganisms as a result of contamination by, for example, contact or coughing, so that the boards act as the spread of microorganisms medium.

[0003] Users of such boards are interested in boards that have an antimicrobial effect to limit the use of antimicrobial products in classrooms or offices.

[0004] Generally, antimicrobial materials and coatings are obtained by adding specific agents with microbicidal activity.

[0005] Preferably inorganic antimicrobial agents, such as metal Ag, Cu, Au, Zn, etc., or metal oxides such as ZnO, CaO or

MgO, or salt such as AgNO₃, Because in contrast to organic antimicrobial agents, they are temperature resistant.

[0006] For metals, actually metal ions (Ag\Cu²\ Zn²⁺Etc.) are active ingredients. This means that moisture must be present in the environment to enable the metal to form ions.

[0007] The antimicrobial activity of metal oxides such as ZnO is attributed to the formation of products capable of penetrating cell walls and killing bacteria. 2, 0 "and 0H_.

[0008] The most commonly used metals are Ag and Cu, which can be added in the following different forms: as nanoparticles, as metal oxide particles, as metal salts or even more complex forms, and as ion exchange media such as on zeolites Ions are added directly.

[0009] Communication boards of enamel-coated steel offer specific advantages, such as their dry-erasability, their acid resistance and color stability, and their durability against wear.

[0010] The antimicrobial enamel in which the antimicrobial agent is integrated into the enamel itself has been described:

[0011] US6303183 (2001) describes an antimicrobial porcelain enamel in which metallic silver is preferably used at a concentration of 0.1 to 3%, but zinc or copper is also used.

[0012] Voss et al. (Evaluation of bacterial growth on various materials, 20^thInternational Ename Ilers Congress, May 15-19, 2005, Istanbul) has clearly demonstrated the antimicrobial effect of silver-containing enamel.

[0013] WO2006/133075 describes a cost-effective and practical acid-resistant porcelain enamel with antimicrobial properties for steel substrates. The porcelain enamel contains an optimal amount of zinc and other ingredients with good antimicrobial properties without having to lose other important properties such as acid resistance.

[0014] More recently, a study by Luca Pignatti et al. described adding Ag to different types of enamel compositions.₂O> CuO and ZnO. The antibacterial test clearly proved the antibacterial effect (Definition of a newrange of porcelain enamels with antibacterial characteristics and the method of the antibacterial power control, 21^st International enameIlers Congress, May 18-22, 2008, Shanghai).

[0015] However, enamel-coated communication boards require an antimicrobial coating on top of the enamel coating, in which antimicrobial action is required, and it is still durable to maintain the antimicrobial action.

[0016] This of course applies to such interactive enameled communication boards, in which their position coding patterns must remain optically readable even after long-term use, and thus the reading instrument must remain capable of forming writing on the communication board Positioning electronic reproduction of the information.

[0017] Such an interactive communication board and the accompanying reading instrument have been described in detail in WO 01/16872, and its content is incorporated into this text by reference to it.

[0018] WO2009/000053 describes an interactive enamel-coated steel communication board on which the position coding pattern has been fixed by applying prints in a ceramic material that is enamel-coated at a temperature of more than 500° C. Anneal on the layer.

[0019] In order to obtain an antimicrobial surface on the enamel surface, a biocide in the form of metal such as silver nanoparticles can be introduced into a layer cast on the surface of the substrate via sol-gel coating, as described in WO2005/115151 .

[0020] The disadvantage of such sol-gel coatings is that they are difficult to apply to the position coding patterns of interactive communication boards.

[0021] Another disadvantage is that the application of such a layer via sol-gel coating is time-consuming, because it includes many steps, such as the generation of metal nanoparticles separate from the coating process itself, and is therefore not well suited to have Continuous industrialized production process with high conveying speed and low cost.

[0022] The technology that enables the application of an antimicrobial layer of metal nanoparticles and metal oxides on a metal substrate at a high conveying speed is chemical vapor deposition.

[0023] In this regard, chemical vapor deposition under atmospheric pressure is particularly attractive because it is suitable for continuous or semi-continuous production processes with high conveying speeds.

[0024] This technique is used to apply a thin metal layer, such as an anti-corrosion layer or a scratch-resistant layer.

[0025] Using thermal chemical vapor deposition at atmospheric pressure, temperatures in excess of 500°C can be reached, and this will achieve the required hardness, durability and structural properties.

[0026] However, at such high temperatures, the oxidizing effect of the vaporized chemicals damages the hot metal surface, and undesirable surface properties appear, making this technology less suitable for coating the metal itself.

[0027] GB2466805 describes a technology that enables the coating of iron or steel materials by chemical vapor deposition under atmospheric pressure.

[0028] To this end, flame assisted chemical vapor deposition at atmospheric pressure is used. The flame provides all or part of the energy needed to stimulate the evaporation process.

[0029] There are two variants of it: chemical vapor deposition with combustion, so that the precursor or its solvent is combustible and therefore contributes to the flame energy; or flame-assisted chemical vapor deposition, so that little or no energy comes from the front The body itself or its solvent.

[0030] GB2466805 uses this technology to apply an antimicrobial layer to a metal substrate at a higher temperature (for example, 300°C).

[0031] To this end, low-cost and low-toxic solvents and chemical precursors are used.

[0032] For example, the silver salt aqueous solution is atomized in a combustible carrier gas such as propane, which generates evaporated silver on the metal substrate at 300° C., and thus the silver layer is composed of several tens or hundreds of nanometers apart. It is composed of small islands of ten nanometers of metallic silver, thereby obtaining good transparency and durability.

[0033] Depending on the desired properties, a second layer composed of approximately 20 nm-1 μm thick silicon dioxide is applied thereon.

[0034] The amount of silver diffused into the silicon dioxide layer can be controlled by temperature.

[0035] Alternatively, silver and silicon dioxide can also be simultaneously applied to a layer in a single vapor deposition process.

[0036] The antimicrobial effect can be further enhanced by re-coating silver in the flame-assisted chemical vapor deposition stage as the final finishing stage.

[0037] Since this technology is suitable for applying an antimicrobial layer at high temperatures (500°C) in a continuous process, we also tested this technology against metal communication boards equipped with enamel coatings on the writing side and the back side.

[0038] Such a communication board is actually manufactured by coating a steel substrate with enamel at a temperature exceeding 500° C., and then, through atmospheric pressure chemical vapor deposition, immediately and continuously providing resistance to the formed enamel-coated steel Microbial coating.

[0039] The object of the present invention is to provide a solution to the aforementioned and other shortcomings by providing an anti-microbial communication board equipped with enamel on both the writing side and the back side of the communication board Coating, and on it, an antimicrobial coating consisting of a composition of antimicrobial metal or metal oxide nanoparticles is applied to the writing side, the antimicrobial coating being applied by sol-gel dip coating, or by means of The chemical vapor deposition of sol-gel coatings at atmospheric pressure is applied to the surface in one or two layers.

[0040] The advantage of such a communication board is that the writing side exhibits a high antimicrobial effect without adversely affecting the properties useful for its use as a communication board.

[0041] In fact, the high scratch resistance and durability of such antimicrobial communication boards, as well as good erasability, good acid resistance and color stability are maintained, and even after many cycles of use Still so.

[0042] The antimicrobial effect is ensured by the wear-resistant layer, which maintains the source of antimicrobial metal ions for the life of the board, because silver ions can continuously diffuse into the sol-gel coating.

[0043] The chemical vapor deposition technology provides the advantage that it can form part of a continuous production process for communication boards, thereby saving production time and thereby being able to avoid material loss, and more particularly silver loss .

[0044] The advantage of silver or silver oxide is that its antimicrobial effect has already appeared at low doses of silver ions. Therefore, the amount of silver or silver oxide in the antimicrobial coating does not need to exceed 10% by weight, and from 0.1 weight % From the start, the antimicrobial effect can already be felt.

[0045] In order to better demonstrate the characteristics of the present invention, in the following, with reference to the accompanying drawings, preferred embodiments of the enameled visual communication board according to the present invention are described through examples without any restrictive nature, in which:

[0046] FIG. 1 shows a schematic perspective view of an antimicrobial communication board according to the present invention;

[0047] FIG. 2 shows a perspective view of a continuous production process for the antimicrobial communication board according to the present invention;

[0048] FIG. 3 shows a discontinuous production process for applying an antimicrobial sol-gel coating to an enameled communication board.

[0049] The antimicrobial enamelled communication board 1 shown in FIG. 1 is mainly composed of a 0.35mm thick steel plate 2 in this case, and the front surface 3 and the back surface 4 of the steel plate 2 are equipped with in this case A 0.035 mm thick enamel inner coating 5, on one side 3, a second mainly white enamel outer coating 6 is applied to it. Then, an antimicrobial sol-gel coating 7 with a thickness of 10-200 nm is applied thereon.

[0050] FIG. 2 shows the continuous production process of the antimicrobial communication board 1 according to the present invention, so that, in the first stage, at a temperature of 820°C, the steel 2 is coated with enamel on both sides; in the second In the stage, a mainly white enamel outer coating is applied to the visible side 6 and annealed at a temperature of about 800°C; in the third stage, by means of chemical vapor deposition under atmospheric pressure, an antimicrobial The metal and metal oxide antimicrobial coating 7 is coated with one layer 7 or two coatings 8, 9 by thermal chemical vapor deposition; the coated communication board Cut it into required specifications or roll it into rolls for subsequent processing, and all of this is in one-time delivery during the production process.

[0051] FIG. 3 shows the production of the antimicrobial sol-gel 12 coating applied to the enamelled communication board 1.

The production process, therefore, the process is not carried out continuously, but carried out in batches, and thus the steel 2 is first provided with an inner enamel coating 5 on both sides at a high temperature, and an outer enamel coating 6 is provided at a high temperature, and then cooled And cut. Then, the enameled communication board 1 is processed in batches in a bath 13 with the required sol-gel 12 coating (ie, the required sol-gel 12 coating is applied by dip coating).

[0052] Experimental part

[0053] In the following experiments, on the one hand, by means of dip coating using 12 layers of silver-containing sol-gel, on the other hand, by means of chemical vapor deposition under atmospheric pressure, the enameled communication board 1 was provided with silver-containing Trim the layer.

[0054] The antimicrobial effect of the 12 layers of the cast sol-gel and the layer deposited by evaporation was determined each time by an antimicrobial test according to ISO 22196 (JIS Z2801), thereby determining certain bacteria attributed to the influence of the antimicrobial layer Strain reduction factor (recuction factor) _oThe reduction factor is the difference between the number of bacteria per square centimeter without the antimicrobial layer and the number per square centimeter with the antimicrobial layer expressed on a logarithmic scale.

[0055] For example, if the number of bacteria drops from 1 million/cm? (Log6) to 100/cm² (Log2), the difference is Log4, or the logarithmic reduction factor is 4.

[0056] Experiment 1

[0057] A solution of the following composition was produced.

[0058] 1) 94% 2-propanol

[0059] 2) 4% TEOS (Tetraethyl Orthosilicate)

[0060] 3) 1% IM AgNO₃ Solution

[0061] 4) 0.8% of HNO3

[0062] To this end, 17.71g TEOS was added to 22.7g2-propanol. The mixture was mixed with 3.41g AgN.₃The 1M solution was mixed and acidified with 3.41 IM HNO3. Then, the mixture was mixed for 20 minutes. After mixing, another 360.40 g 2-propanol was added.

[0063] The solution is applied by means of dip coating, thereby obtaining a layer with a thickness of 40-60 nm, followed by a temperature of 400° C.

10 minutes heat curing step.

[0064] In order to implement antimicrobial testing, use:

[0065] 1) Suspension medium: nutrient broth 1/500NB;

5xl0 [0066] 2) Inoculum test: Dilute 1/500NB of bacterial suspension to obtain 2. 5xl0⁵Up to 10x10^s The bacterial concentration of cells/ml, the target concentration is 6x105 cells_/ml ；

[0067] 3) The following bacterial strains:

[0068]-Staphylococcus aureus

[0069]-Escherichia coli.

[0070] 4) Cultivation: The sample inoculated with the bacterial suspension is incubated at a temperature of 35+/-1°C for 24+/-1 hours at a relative humidity of not less than 90%.

[0071] For E. coli bacteria, the following antimicrobial effects were measured:

[0072] No antimicrobial layer: 13, 666, 667KVE/ml or 854, 167KVE/cm² (Log 7. 13 or Log 5. 88).

[0073] With antimicrobial layer: 17KVE/ml or 1KVE/cm² (Logl. 23 or LogO).

[0074] Therefore, the reduction factor attributed to the antimicrobial layer is Log5.9 or a reduction of about one million times.

[0075] Experiment 2

[0076] A solution of the following composition was produced.

[0077] 1) 94% 2-propanol

[0078] 2) 4% TEOS (tetraethyl orthosilicate)

[0079] 3) 1% IM AgNO₃ Solution

[0080] 4) 0.8% Hl·©

[0081] To this end, 17.71g TE0S was added to 22.7g 2-propanol. The mixture was mixed with 3.41g AgN.₃The 1M solution was mixed and acidified with 3.41 IM HNO3. Then, the mixture was mixed for 20 minutes. After mixing, another 360.40 g 2-propanol was added.

[0082] By atomization in propane, the solution is applied by means of chemical vapor deposition with combustion, whereby the energy of the flame is used to thermally cure the coating. Obtain a coating thickness of 40-60nm.

[0083] The antimicrobial test for Escherichia coli as described above has the following results.

[0084] No antimicrobial layer: 12, 100,000 KVE/ml or 756, 250 KVE/cm² (Log 7. 08 or Log 5. 88).

[0085] With antimicrobial layer: 99,017KVE/ml or 6,245KVE/cm² (Log5. 0 or Log3. 8).

[0086] Therefore, the reduction factor through the antimicrobial coating is Log2.1 or reduced by more than 100 times within 24 hours.

[0087] It goes without saying that the continuous production process of chemical vapor deposition using antimicrobial agents is more effective and more cost effective than the non-continuous production process of using antimicrobial sol-gel liquid coating solutions.

[0088] The present invention is by no means limited to the embodiments described as examples and shown in the drawings, and other embodiments in which antimicrobial sol-gel or chemically deposited antimicrobial ingredients are chemically deposited by evaporation can also be used to achieve such a configuration. The communication board of antimicrobial metal or metal oxide does not go beyond the scope of the present invention.