JP5982006B2 - Manufacturing method of antibacterial communication board - Google Patents

Description

The present invention provides a bi-directional (or otherwise) optical communication board coated with enamel, ie a white board that can be written using an erasable felt pen, or a colored board that can be written using chalk. It is about blackboards.

Because the communication board provided in the office or classroom is used by many people every day, the communication board bears the potential risk of transmitting microorganisms, for example as a result of contamination by contact or coughing, and acts as a microbial infection medium become.

Users of such boards are interested in antibacterial boards to limit the number of antibacterial products used in the classroom or office.

  In general, antibacterial agents or antibacterial coatings are obtained by adding specific agents with antibacterial action.

Inorganic materials with antibacterial properties, such as metals (such as Ag, Cu, Au, Zn), metal oxides such as ZnO, CaO or MgO, or salts such as AgNO ₃ have antibacterial properties. Unlike organic materials, it is desirable because of its resistance to temperature.

For some metals, the active component is actually a metal ion (Ag ⁺ , Cu ²⁺ , Zn ^2+, etc.). This means that the metal must have moisture in order for the metal to form ions.

Antimicrobial effects of metal oxide such as ZnO _{is, H 2 O 2, O ·} ( oxygen radical), which penetrates the walls of the cells can kill bacteria and OH ^- due to the formation of.

  The most prevalent metals are Ag and Cu, which can be added as nanoparticles, as metal oxide particles, in metal salts or in more complex forms, and in ion exchange media such as zeolites. It can also be added directly in various forms as ions.

  Enamel-coated steel communication boards have certain advantages such as erasability when dry, acid resistance, discoloration resistance, and even abrasion resistance.

  The antibacterial enamel in which the antibacterial agent is integrally incorporated in the enamel itself has already been disclosed as follows.

  US Pat. No. 6,303,183 (registered in 2001) describes an antibacterial wrinkle where metallic silver is preferably used at a concentration of 0.1% to 3%, but zinc or copper is also used.

Antibacterial effect of enamel containing silver has been clearly demonstrated by Voss et al. (Paper presented at the meeting, which was held in Istanbul on May 15 to 19, 2005 "20 ^th International Enamellers Congress", "Evaluation of bacterial growth on various materials ").

  WO 2006/133075 describes a cost-effective and practical acid-resistant kite with antibacterial properties for a steel substrate. The soot contains an optimal amount of zinc or other composition with sufficient antimicrobial properties without losing other important properties such as acid resistance.

More recently, a research paper by Luca Pignatti et al. Describes the addition of Ag ₂ O, CuO and ZnO to another type of enamel composition (performed in Shanghai on May 18-22, 2008). paper presented at the crack was meeting "21 ^st International enamellers Congress", "Definition of a new range of porcelain enamels with antibacterial characteristics and the method of the antibacterial power control ").

  However, an enameled communication board needs to be an antibacterial coating that not only has an antibacterial action on the enamel cover but also has durability to maintain the antibacterial action.

  This is certainly true if the position coding pattern is held optically readable even after long-term use and the reading device cannot electronically reproduce the information written on the communication panel at a predetermined position. It is applied to a bidirectional communication board with enamel coating.

  Such a bi-directional communication board and accompanying reading device are described in WO 01/16872, the contents of which are incorporated in this specification with reference thereto.

  WO 2009/000053 describes a steel two-way communication board with enamel coating, which is located by printing on the ceramic material annealed to the surface of the enamel at a temperature above 500 ° C. A coding pattern is attached.

  In order to obtain an antibacterial surface on the enamel surface, as described in WO2005 / 115151, a biocide in the form of a metal such as silver nanoparticles is cast on the surface of the substrate by a sol-gel coating method. May be incorporated into several layers.

  The disadvantage of such a sol-gel coating is that it is difficult to apply to the position coding pattern of an interactive communication board.

  Another disadvantage is that it takes time to apply several such layers by the sol-gel coating method. Because it involves several steps, such as making metal nanoparticles separately from the coating process itself, resulting in a continuous industrial production process that achieves low cost with fast passage speed in the manufacturing process This is because it is more unsuitable.

  A technique that makes it possible to apply an antibacterial layer of metal nanoparticles or metal oxides to a metal substrate at a fast passage speed in the manufacturing process is chemical vapor deposition.

  Chemical vapor deposition at normal pressure is particularly suited for this purpose. This is because it is suitable for a continuous or semi-continuous production process where the passing speed in the manufacturing process is high.

  This technique is used to apply a thin metal layer such as a rust stop layer or a scratch resistant layer.

  Thermal chemical vapor deposition at normal pressure reaches temperatures in excess of 500 ° C., thereby obtaining the desired hardness, durability and structure.

  However, at such high temperatures, the hot metal surface is damaged by the oxidation of the deposited chemicals, which increases the undesirable properties of the surface, and this technique is more effective for coating the metal itself. That would be inappropriate.

  British Patent GB 2466805 describes a technique that allows coating of iron or steel by chemical vapor deposition at normal pressure.

  For this purpose, flame-assisted chemical vapor deposition at atmospheric pressure is used, which provides all or part of the energy required to operate the vapor process. To do.

  There are two variations of chemical vapor deposition. One is combustion chemical vapor deposition, where its precursor or its melt is flammable and therefore contributes to the energy of combustion. The other is flame-assisted chemical vapor deposition in which little or no energy is obtained from its precursor or its melt.

  In British patent GB 2466805, this technique is used to apply an antibacterial layer to a substrate at higher temperatures (eg, 300 ° C.).

  For this purpose, low-cost and less toxic precursors and melts are used.

  For example, a water soluble solvent of silver salt is atomized in a combustion carrier gas such as propane, thereby producing silver vaporized on a metal substrate at 300 ° C., where the layer of silver is Good transparency and durability can be obtained because several tens of nanometers of metallic silver separated from each other by tens or hundreds of nanometers are made of isolated islands. It was.

  On top of this a second layer is applied, which consists of silicon dioxide with a thickness of about 20 nm to 1 μm, depending on the desired properties.

  The amount of silver diffusing into this silicon layer can be controlled by temperature.

  Alternatively, silver can be applied to a layer simultaneously with silicon in a single deposition process.

  The antibacterial action can be further enhanced by coating again with silver in a flame assisted chemical vapor deposition as a final finishing step.

  Since this technique is suitable for applying an antibacterial layer in a continuous process at high temperatures (500 ° C.), we also tested it on a metal communication board with an enamel coating on the writing and back surfaces.

  Such a communication board is manufactured by, of course, enamelling the steel base at a temperature above 500 ° C. and then applying the antibacterial coating by chemical vapor deposition immediately and at atmospheric pressure on the enamel-coated steel. To do.

The object of the present invention is to provide a solution to the above or other disadvantages, which comprises an enamel coating annealed at a temperature above 500 ° C. on both the writing surface and the back surface of the communication board, said writing surface. Is coated with an antibacterial coating consisting of a number of nanoparticles of an antibacterial metal or an antibacterial metal oxide or an antibacterial metal salt, the antibacterial coating being a sol-gel dip coating or atmospheric pressure The solution is to provide an antibacterial communication board that is applied by one or two layers to the surface by chemical vapor deposition of a sol-gel coating.

  The advantage of such a communication board is that the writing surface exhibits a high antibacterial action without adversely affecting the beneficial properties of the application as a communication board.

  Certainly, the high scratch resistance and durability of such antibacterial communication boards, as well as enabling good wiping, good acid resistance and good discoloration resistance are ensured, these properties are many times It is maintained even after use for a long time.

  The antimicrobial action is ensured by a long-lasting layer that is maintained as a source of antimicrobial metal ions for the lifetime of the board. This is because silver ions can constantly diffuse into the sol-gel coat.

  Chemical vapor deposition technology can form part of the continuous production process of numerous communication boards, thereby reducing manufacturing time and preventing material loss, more specifically silver loss. There is an advantage of being able to.

  The advantage of silver or silver oxide is that it has already produced an antibacterial effect with a small amount of silver ions used, and the amount of silver or silver oxide required in the antibacterial coating is only 10% by weight. It is in. Incidentally, an antibacterial action has already been observed at 0.1% by weight.

1 shows a schematic perspective view of an antibacterial communication board according to the present invention. FIG. The perspective view of the continuous production process of the antibacterial communication board by this invention is shown. A discontinuous production process for applying an antibacterial sol-gel coating on the surface of an enameled communication board is shown.

  In order to better illustrate the features of the present invention, a preferred embodiment of an enamel-coated bi-directional optical communication board according to the present invention will be described by way of example, without limitation, with reference to the accompanying drawings. This will be described later.

  The antibacterial enameled communication board 1 shown in FIG. 1 is first made of a steel plate with a thickness of 0.35 mm in this example, with a front surface 3 and a back surface 4 of 0.035 mm in this example. An undercoat 5 with a thick enamel is applied, and a second, mainly white enamel overcoat 6 is applied on one side 3 thereof. Further thereon, an antibacterial sol-gel coating 7 having a thickness of 10 to 200 nm is applied.

  FIG. 2 shows a continuous production process of the antibacterial communication board 1 according to the present invention. In the first stage, both sides of the steel 2 are enameled at a temperature of 820 ° C., and in the second stage, the eye of those faces The surface to be touched is overcoated mainly with white enamel and annealed at a temperature of about 800 ° C. In the third stage, the enamel topcoat is coated with an antibacterial coating 7 comprising an antibacterial metal and a metal oxide as a single layer by thermal chemical vapor deposition, or chemical vapor deposition at normal pressure. Coated as two layers by the method, cutting the coated communication board into the desired format or rolling it for the next step is all done in one flow throughout the production .

  FIG. 3 shows the production process of applying the antibacterial sol-gel 12 coating to the enamel-coated communication board 1, which does not proceed continuously but is divided into several times. Enamel is primed on both sides at high temperature, and enamel is primed at high temperature, then cooled and cut. The enamel-coated communication board 1 is then processed in a solution tank 13 by coating with a desired sol-gel 12 to which the desired dip coating method is applied in a batch mode.

Experimental Data Enamel-coated communication board 1 was provided with a silver-containing finish layer by dip coating of 12 silver-containing sol-gel layers or chemical vapor deposition at normal pressure in the following experiments.

The antibacterial action of the cast sol-gel 12 layer and the layer formed by vapor deposition is measured each time by an antibacterial test according to ISO 22196 (JIS Z2801), and the rate of bacterial reduction due to the action of the antibacterial layer for a certain strain is measured. It was. The bacterial reduction rate is expressed on a logarithmic scale as a difference between the number of bacteria per unit cm ² when the antibacterial layer is not used and the number of bacteria per unit cm ² when the antibacterial layer is used. Is done.

For example, when the number of bacteria is 1 million per 1 cm ² (Log 6) to 100 per 1 cm ² (Log 2), the difference is Log 4 and the bacterial reduction rate by logarithm is 4.

Experiment 1
A solution of the following mixture was made.

2-propanol 94%
TEOS (tetraethyl orthosilicate) 4%
1 mol AgNO ₃ solution 1%
HNO ₃ 0.8%

For this purpose, 17.71 g TEOS was added to 22.7 g 2-propanol. This mixture was mixed with 3.41 g of a 1 molar solution of AgNO ₃ and oxidized with 3.41 g of 1 molar solution of HNO ₃ . This mixture was then mixed for 20 minutes. After mixing, an additional 360.40 g of 2-propanol was added.

  The solution was applied by dip coating, resulting in a layer thickness of 40-60 nm, followed by a heat curing step at 400 ° C. for 10 minutes.

The following were used to perform antibacterial tests.

Suspension medium: NB medium 1/500 NB

Inoculation Test: 1/500 suspension of bacteria in the NB, the target density of 6x10 ⁵ cells / ml, in order to obtain a concentration of bacteria between 2.5x10 ⁵ cells / ml and 10x10 ⁵ cells / ml, were diluted .


The following strains:
-Staphylococcus aureus-E. coli

Incubation: Several samples inoculated with the bacterial suspension were cultured at 35 +/− 1 ° C. for 24 +/− 1 hour at 90% relative humidity.

The following antibacterial activity was measured against E. coli bacteria.

Without antibacterial layer: 13,666,667 KVE / ml, or 854,167 KVE / cm ² (Log 7.13, or Log 5.88).

When there is an antibacterial layer: 17 KVE / ml, or 1 KVE / cm ² (Log 1.23 or Log 0).

  The bacteria reduction rate due to the antibacterial layer is eventually Log 5.9, that is, a reduction rate of about 1 million.

A solution with the following composition was made.

2-propanol 94%
TEOS (tetraethyl orthosilicate) 4%
1 mol AgNO ₃ solution 1%
HNO ₃ 0.8%

For this purpose, 17.71 g TEOS was added to 22.7 g 2-propanol. This mixture was mixed with 3.41 g of a 1 molar solution of AgNO ₃ and oxidized with 3.41 g of 1 molar solution of HNO ₃ . This mixture was then mixed for 20 minutes. After mixing, an additional 360.40 g of 2-propanol was added.

This solution is applied by chemical vapor deposition with combustion by spraying on propane, and the energy of the flame is used to heat cure the coating. A coating thickness of 40-60 nm was obtained.

The antibacterial test was performed as described above for E. coli, and the following results were obtained.

Without antibacterial layer: 12,100,000 KVE / ml, or 756,250 KVE / cm ² (Log 7.08, or Log 5.88).

With antibacterial layer: 99,017 KVE / ml, or 6,245 KVE / cm ² (Log 5.0 or Log 3.8).

The bacteria reduction rate due to the antibacterial coating eventually results in a reduction of over 100 in Log 2.1 or 24 hours.

  The continuous production process of the antibacterial agent using the chemical vapor deposition method is much more efficient and cost effective than the non-continuous production process using the antibacterial sol-gel solution coating solution.

  The present invention is in no way limited to the examples described by way of example in this specification and drawings, and a communication board comprising an antibacterial metal or metal oxide may be coated with an antibacterial sol-gel, Alternatively, other implementations in which the antimicrobial composition is chemically deposited by vapor can be realized without departing from the scope of the present invention.

Claims (6)

An enamel coating (5) annealed at a temperature exceeding 500 ° C. is provided on both the writing surface and the back surface of the communication board (1), and the writing surface is provided with a sol-gel (12) dip coating or a sol-gel coating at normal pressure. Chemical vapor deposition of an antibacterial coating (7) consisting of a number of nanoparticle components of one type of antibacterial metal or one type of antibacterial metal oxide or one type of antibacterial metal salt A method for producing an antibacterial communication board (1) , characterized in that it is applied by one (7) or two (8, 9) layers, and the metal oxide is silicate or silver oxide . The method for producing an antibacterial communication board (1) according to claim 1, wherein the antibacterial metal is silver or copper . The method for producing an antibacterial communication board (1) according to claim 1, wherein the chemical vapor deposition is chemical vapor deposition or combustion chemical vapor deposition with flame assistance at normal pressure. The method for producing an antibacterial communication board (1) according to claim 1 or 2, wherein the metal or metal salt is made of silver or silver nitrate . The method for producing an antibacterial communication board according to claim 1, characterized in that, by the action of the antibacterial coating (6), the number of E. coli per unit area is reduced at a reduction rate of at least 100 in 24 hours. . 2. The method of manufacturing an antibacterial communication board (1) according to claim 1, wherein the method comprises annealing both sides of the steel (2) at a temperature of 820 [deg.] C. in the first stage; Surface (6) is coated with mainly white enamel and annealed at a temperature of about 800 ° C .; antibacterial coating with antibacterial metals and metal oxides by thermal chemical vapor deposition in the third stage (7) Is applied in one layer (7) or two layers (8), (9); the coated communication board is cut into a desired format or rolled for subsequent processing. A method characterized by comprising a continuous production process realized by a single manufacturing flow.

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