KR101268956B1 - Ion exchange method for strengthening or simultaneous antibacterial treatment of glass for display and the product of the same - Google Patents

Abstract

The present invention relates to an ion exchange method for tempered or simultaneous antibacterial treatment of display glass and to a glass for display tempered or concurrently antibacterial treatment by the method, and more particularly, by etching at least one surface of the glass substrate surface First strengthening the glass substrate by removing the oxide film and the microcracks; Ion exchange by contacting or applying a potassium-based material to the etched at least one surface of the glass substrate to strengthen the glass substrate by secondary; ion exchange method for the strengthening or simultaneous antibacterial treatment of the glass for display comprising the Thereby providing a glass for display which is tempered or simultaneously antibacterial.
According to the present invention as described above, the glass substrate may be first strengthened by performing an etching process on at least one surface of the glass substrate in advance, and then secondly strengthened by performing ion exchange thereon, so that the glass substrate may have a strength value of 600 MPa or more. In the ion exchange strengthening method of glass by immersion of molten salt, the properties of each tempered glass are different according to the immersion order, the location of the immersion, etc., while maintaining the same process variables and conditions while maintaining the same physical properties. It can be reproducibly strengthened, and by strengthening the glass substrate under such batched process variables and conditions, it is possible to reduce the defect rate and increase the yield, and to increase the reliability of the product because the glass product for the final display has the same physical properties.

Description

Ion exchange method for strengthening or simultaneous antibacterial treatment of glass for display and the product of the same}

The present invention relates to an ion exchange method for tempered or simultaneous antibacterial treatment of display glass and to a glass for display tempered or concurrently antibacterial treatment by the method, and more particularly, by etching at least one surface of the glass substrate surface First strengthening the glass substrate by removing the oxide film and the microcracks; Ion exchange by contacting or applying a potassium-based material to the etched at least one surface of the glass substrate to strengthen the glass substrate by secondary; ion exchange method for the strengthening or simultaneous antibacterial treatment of the glass for display comprising the Thereby providing a glass for display which is tempered or simultaneously antibacterial.

According to the present invention as described above, the glass substrate may be first strengthened by performing an etching process on at least one surface of the glass substrate in advance, and then secondly strengthened by performing ion exchange thereon, so that the glass substrate may have a strength value of 600 MPa or more. In the ion exchange strengthening method of glass by immersion of molten salt, the properties of each tempered glass are different according to the immersion order, the location of the immersion, etc., while maintaining the same process variables and conditions while maintaining the same physical properties. It can be reproducibly strengthened, and by strengthening the glass substrate under such batched process variables and conditions, it is possible to reduce the defect rate and increase the yield, and to increase the reliability of the product because the glass product for the final display has the same physical properties.

It is known that glass reinforcement methods include thermal reinforcement, chemical reinforcement, and physical reinforcement methods. Among these, chemical strengthening is reported to have the advantages of similar stress distribution to crystallized glass, a moderate stress gradient, and no rapid transition from compression to tension.

A typical chemical strengthening method is the ion exchange method, which converts alkali ions such as Li ⁺ and Na ^{+ on the} surface of the glass into alkali ions such as Na ⁺ and K ⁺ having a larger ion radius and the same charge. It is a method of increasing the strength by forming a compressive stress as the volume of the glass surface is increased by substitution.

The ion exchange method described above is a function of temperature and time since it is a Diffusion-controlled process. As a result, the higher the temperature of the ion exchange, the shorter the time required to produce a compressed layer of real thickness. The increase in strength that can be achieved by ion exchange is governed by the processing conditions, namely temperature and time, and for a given glass composition the maximum strength is achieved in a shorter time as the temperature increases. The thickness of the compressive layer can vary from several hundred to several thousand micrometers depending on the exact glass composition, processing conditions, and starting glass thickness. If the layer is very thin relative to the total thickness of the glass, the balance strength is so small that, unlike thermally strengthened glass, chemically tempered glass has the advantage of being able to be cut or machined after treatment.

Such an ion exchange method generally refers to a case where a molten salt immersion method is used. The molten salt immersion method is a method of strengthening glass by immersing glass in an alkali molten salt and exchanging molten salt-containing ions and glass-containing ions. First, the glass to be ion-exchanged is heated at a transition temperature of 300 to 450 ° C or lower. On the other hand, the alkali salt is melted at a temperature of 380 ° C. or higher, and then the glass preheated to the molten salt is deposited and held for a predetermined time or more to form a compressive stress layer on the surface of the glass to strengthen it.

However, the molten salt immersion method must be equipped with a device for heating the glass in advance and a molten salt bath separately to increase the size and complexity of the equipment, and the heating process such as ion exchange or preheating must be intermittently without continuity, and also strengthened. Depending on the immersion order of the target glass can be a difference in the retention time for strengthening may cause a difference in the degree of strengthening, and also, because a difference in the substitution target ion concentration of the molten salt occurs according to the repeated strengthening process, Conditions had to be corrected or molten salts had to be replaced and reheated, resulting in a complicated process.

In addition, in the ion exchange process using molten salt, the salt is heated at a specific temperature and the glass is deposited to proceed with the ion exchange process. Even though the salt is heated and completely melted, the temperature in all parts (positions) of the molten salt bath is increased. It is difficult to see the same, and thus this causes a problem that the temperature, which is the most important condition of ion exchange, varies depending on the location, and thus, it was difficult to stably implement the same final physical properties.

In addition, considering the process temperature and the holding time, the ion exchange process for infiltrating the antibacterial component such as Ag or Cu by molten salt has a relatively high temperature and holding time in the range of 300 to 450 ° C. There was also an uneconomical problem in terms of temperature and maintenance time for about 1 hour.

In addition, the ion exchange process by molten salt is difficult to see evenly distributed concentration of ions of Ag or Cu in all parts of the molten salt bath. The concentration of the ions distributed is difficult to achieve the same physical properties, which also has a problem of lowering the yield for the normal final product.

On the other hand, in performing the ion exchange process, there are certain limitations in terms of strength or light transmittance of the ion-exchanged glass, and thus, it is necessary to derive more desirable process elements to overcome these limitations. to be.

The present invention has been made to solve the above-described problems, the present invention is to first strengthen the glass by performing an etching process on at least one surface of the glass substrate in advance, and then secondary strengthening by performing ion exchange to 600MPa To prepare a high strength glass substrate having the above strength value, and by removing the flaw of the glass surface as much as possible by the etching process to reduce the loss of light transmittance even after ion exchange or to maintain the light transmittance level before and after ion exchange For the purpose of

In addition, the present invention is strengthened, unlike the conditions of the ion exchange is changed due to the order of immersion in the same sequence in the ion exchange method by the molten salt immersion, the change of the ion concentration of the substitution target in the molten salt according to the repeating process, etc. The target glass substrates can be tempered or antibacterial while maintaining the same conditions as much as possible, and the other purpose is to reduce the defect rate and increase the yield of the display glass by strengthening or antibacterial the glass substrate under the same conditions.

In addition, another object of the present invention is to increase the reliability of the product by allowing the final glass substrate reinforced or antimicrobial treated by the same ion exchange process to have the same physical properties as a whole.

In addition, with the recent trend of eco-friendly and well-being, the nature of glass, an eco-friendly material, and the expansion of the mobile display market and the spread of smartphones and tablet PCs, many devices are using touch-based operation systems. In light of the environment in which it is used, it is another object to maintain the cleanliness of the display area itself in touch-based devices, but in particular to establish optimum ion permeation conditions by ion exchange, a new method. do.

In addition, the present invention is based on the invention features that both the antibacterial and strengthening of the glass in a similar temperature range, it is possible to give the function of reinforcement and antimicrobial at the same time in a single process instead of two processes economical of the process It is another purpose to be able to pursue.

In addition, the present invention is to recognize and solve the disadvantage that the conventional molten salt immersion method is intermittently proceeded to the preheating process and the immersion process for ion exchange, it can be carried out continuously from the coating to ion exchange. Therefore, it has a great advantage in the process, it has the characteristics to proceed the process simultaneously or continuously until the antibacterial treatment.

This is expected to be effective in terms of economics and time as it can reduce one process in the industrial view. In addition, as mentioned above, the interest in display glass is increasing due to the spread of portable display. To achieve the purpose of environment-friendly by providing antimicrobial functionality, at the same time to ensure the safety of the glass for display.

The present invention to achieve the above object, by etching at least one side of the glass substrate to remove the oxide film and fine cracks on the surface of the glass substrate to first strengthen the glass substrate; It provides an ion exchange method for strengthening the glass for a display, comprising the step of ion-exchanging the glass substrate by contacting or applying a potassium-based material on at least one etched surface of the glass substrate.

As a result of removing the oxide film and the microcracks through the etching, a glass having a light transmittance value of 90 to 93% is manufactured.

The potassium-based material is preferably a solution containing powder, ground powder or sol of potassium nitrate.

In the ion exchange step, it is preferable to perform a heating process including a heating history of maintaining a temperature increase rate of 8 to 15 ° C. per minute and heating at a temperature of 440 to 460 ° C. for 10 to 20 minutes in order to increase the temperature to the ion exchange temperature. Do.

The second step of strengthening the glass substrate is preferably a step of simultaneously strengthening the glass substrate by simultaneously adding silver or a copper material to the glass substrate and providing antimicrobial activity.

After the second step of strengthening the glass substrate, it is preferable to further include the step of ion exchange by contacting or applying a silver or copper-based material to impart antimicrobial properties to the glass substrate.

In the step of imparting antimicrobial activity, the heating rate is 8 to 15 ° C. per minute when the temperature is raised to the ion exchange temperature, and a heating history of applying a holding time of more than 0 minutes and 10 minutes or less at a temperature of 240 to 280 ° C. It is preferable to carry out the heating process.

It is preferable to contact or apply silver or copper-based material only on one surface of the glass substrate.

Ion exchange is applied on both sides of the glass substrate, but it is preferable that the relative amount of silver or copper-based material to potassium-based material is more than 0 and 0.05% or less.

The silver-based material and the copper-based material are preferably powders, powders or solutions of silver nitrate and copper nitrate, respectively.

In addition, the present invention is prepared by the above method to provide an ion exchange tempered glass having a light transmittance of 90 to 93%, an intensity value of 650 ~ 700MPa.

In addition, the present invention is prepared by the above method to provide an ion exchange strengthening and antibacterial glass having a light transmittance of 90 ~ 92%, an intensity value of 580 ~ 620MPa.

According to the present invention as described above, the strength of the glass is drastically increased, so that the risk of breakage caused in handling can be greatly reduced.

In addition to the polishing method, the present invention may improve the strength of the glass by introducing the etching method of the glass, or the light transmittance may not be lowered or increased even by the ion permeation process for the antibacterial treatment. Both the improvement and the strength can be improved.

In addition, unlike the ion strengthening by the molten salt immersion method, which requires the equipment to be constructed separately, there is no need to construct a separate complex or large equipment other than the heat treatment equipment, and the process up to ion exchange can be continuously performed. This can simplify equipment and simplify the process.

In addition, by solving the problem that the degree of strengthening of the glass due to the concentration gradient according to the position of the molten salt bath in the molten salt dipping method, it is possible to improve the reliability of the reinforced glass product.

Since the process of ion exchange by the solid-state coating method or the spreading powder according to the present invention is performed within 10 minutes at a relatively lower temperature of 260 ° C (Ag +) and 230 ° C (Cu2 +), in terms of unit cost and yield, There is an excellent effect.

In addition, the ion exchange by the solid phase coating method or the liquid phase coating method shows a higher yield than the molten salt method, which is a conventional strengthening method, due to the stable temperature gradient of the furnace used during ion exchange.

The molten salt method, which is a chemical strengthening method of conventional glass, is complicated in its process and requires a long time of several hours to several tens of hours in order to obtain a practical surface compressive stress layer, resulting in low productivity, and problems such as deterioration of ion exchange reaction due to adsorption of impurities. In particular, in order to use to strengthen the LCD glass, the glass used in the LCD is mostly thin because the thickness is about 0.7mm thin and large size causes a problem that the distortion occurs. In addition, the entire glass is ion-exchanged, which may affect the circuit coated on one surface of the glass, making it difficult to drive, and because impurities contained in the ion-exchange solution cause fine corrosion on the surface of the glass after ion exchange, the glass for display There is a restriction to use it as a strengthening method. There is also a need to develop a system that can cope with changes in concentration of reinforcement solutions due to ion exchange in mass production processes. In order to solve these problems, first, we found the optimized ion exchange conditions and anticipated problems in the production process to establish the process conditions for producing tempered glass or antibacterial glass finished products with uniform optical and mechanical properties.

After exchange of K + ions for glass strengthening, ion exchange penetrates Ag + and Cu + ions for antimicrobial in glass to check the optimum conditions for strengthening glass according to ion exchange temperature and time and antibacterial activity against many bacteria in living environment It is an object of the present invention and an effect derived therefrom to produce a multifunctional tempered glass such as tempered glass, antibacterial, scratch resistance and the like in parallel with the evaluation.

1 is a process chart showing a flow from processing of the glass substrate to the ion exchange process according to an embodiment of the present invention.
2 is a graph showing ion exchange conditions according to a preferred embodiment of the present invention.
3 to 6 are profiles of the distribution of K + ions in the surface of the strengthened glass substrate under ion exchange conditions corresponding to Table 6, which is one preferred embodiment of the present invention.
7 to 9 are graphs showing the distribution of K + ions and Ag + ions in the glass substrate surface under ion exchange conditions corresponding to Table 7, which is a preferred embodiment of the present invention.
10 to 12 are graphs showing the distribution of K + ions and Ag + ions in the glass substrate surface under ion exchange conditions corresponding to Table 9, which is a preferred embodiment of the present invention.
13 and 14 are graphs showing light transmittances obtained by etching a glass substrate in a NaOH solution according to a preferred embodiment of the present invention.
15 and 16 are photographs showing the antimicrobial treatment of glass according to one embodiment of the present invention, and the results of the antimicrobial evaluation thereof for the cultured Salmonella bacteria and E-coli.
FIG. 17 is a photograph showing antimicrobial treatment of glass by the solid phase coating method according to an embodiment of the present invention, and treatment of the antimicrobial evaluation result against the cultured Staphylococcus aureus.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments.

The destruction of glass has the following characteristics.

1. The strength of glass is 100 ~ 1000 times smaller than the theoretical value.

2. Destruction always starts on the surface.

3. The average deviation of the intensity observed in the same sample group is 15 to 20%.

4. The discrepancy between theoretical and real strengths is due to the flaw on the glass surface.

That is, the breakdown of the glass begins from the surface by the presence of stress concentration defects. Thus, the glass can be strengthened by eliminating or minimizing these defects or by compressing the surface to create a compressive stress on the surface before the defects increase under tension. The strength of glass with surface compressive stress is equal to "breaking strength of untreated glass plus magnitude of compressive stress".

In the present invention, various variables were considered in order to maximize the strengthening of glass, especially considering the mass production process, considering the processing speed, the size of the system for the treatment, and at the same time deriving a manufacturing method for the glass having the best strength characteristics. Therefore, the glass strengthening process of the present invention described below is to maximize the effect of the glass strengthening through the organic bonding relationship of each process.

The present invention is to reinforce the glass (size around 20 inches) for small display devices, such as mobile phones, notebooks, and even to antibacterial treatment, the shape processing is completed, but the strengthening, anti-bacterial treatment, such as not complete mass reinforcement of the mass Or antimicrobial treatment method is considered. However, the present invention should not be construed as being limited to the glass for such a small display device, and it should be noted that the glass may be applied regardless of its use.

In short, the present invention, by applying the solid phase coating method, the liquid coating method to improve the problems of the melt immersion method for ion permeation, and introduced the etching method to enhance the mechanical properties such as optical properties, strength, such as light transmittance It is characterized by.

Here, the solid phase coating method is defined as a process of ion-exchanging salts from a glass surface by contacting a solid salt with glass, and the solid salt is used as a powder, but is not limited to powder. In addition, the liquid coating method may be defined as a process of applying a liquid phase and then ion exchange.

1 shows a process chart from processing of a glass substrate to ion exchange in order to manufacture a display glass according to an embodiment of the present invention.

<Production of Glass Substrate>

The composition and physical properties of the mother glass substrate used for reinforcement and / or antibacterial in the present invention are shown in Table 1 below.

Chemical composition
(wt.%) 70-73 SiO ₂ , 13-15 Na ₂ O, 7-12 CaO, 1.0-1.9 Al ₂ O ₃ ,
1.0 ~ 4.5 MgO, 0.02 TiO ₂ , 0.08 ~ 0.14 Fe ₂ O ₃ Glass transition temperature (℃) 500 Refractive Index 1.51 Softening temperature (℃) 730 Hardness (H _v ) 549.7 Transmittance (%) 91.83 (370-700 nm) Fracture toughness (MPam)  0.7144 Reflectance (%) 4.13 (single face) 3-Point Bending Strength (MPa) 151.5

The mother glass substrate having the composition and physical properties as described above was processed to be evaluated by reinforcing or antibacterial treatment. In particular, in order to measure the mechanical properties such as strength was processed to suit the strength measurement, using the specimens thus processed, the reinforcement by ion exchange, observation of the microstructure was performed in parallel. The details are as follows.

1. Processing

In consideration of the 3-point bending strength measurement, the mother glass substrate was processed to a size of 3 × 0.7 × 3.6mm.

2. washing and drying

The cut glass substrate was ultrasonically washed with ethanol and distilled water and then blown with N ₂ gas and dried at 100 ° C. for 10 minutes in a drier.

3. Polishing

The cutting edges and the surfaces were polished using SiC abrasive cloth (# 400, 600, 800, 1000, 1200, 1500, 2000, 2400, 4000) to remove the fine cracks generated at the edges of the cut glass substrate. .

4. washing and drying

The polished mother glass substrate was ultrasonically washed with ethanol and distilled water and then blown with N ₂ gas, and dried in a drier at 100 ° C. for 10 minutes.

5. Etching

The washed and dried mother glass substrate was etched by immersion in an aqueous solution of about 0.2 N concentration of hydrochloric acid (HCl) for about 30 seconds. Here, since the etching solution and concentration can be applied in various ways, the above etching solution and concentration is not limited to the above solution and concentration.

In relation to the etching process, the strength of the base glass substrate having a thickness of 0.55 mm is only 206.4 MPa on the basis of the three-point bending strength, but the strength after the ion exchange (450 ° C./10 min condition) is significantly improved to 471.1 MPa. Indicated. Here, if the etching process before the ion exchange is further shown, the strength after the ion exchange is not shown, but has a maximum strength of 891.4 MPa, and thus it can be seen that the strength value is much higher than that of the mother glass. This strength value of up to 891.4 MPa far exceeds the expected value, and can be evaluated with the obvious effect derived from the introduction of the etching process. On the other hand, after performing only the etching process and measured the strength value shows a value of 156.9 MPa, the etching alone has no effect of increasing the strength, but after reducing the fine cracks of the surface due to the etching, as described later, using a solid-state coating using KNO ₃ powder When ion exchange was carried out by the liquid coating method using the method or liquid KNO ₃ , the effect of etching can be maximized by the penetration of K + ions into the glass surface. The surface compressive stress is uniformly formed by removing the surface microcracks by etching, and the strength is maximized by fine control of ion exchange temperature and time.Etching and ion exchange is an excellent strength effect exceeding expectations due to the organic bonding of the process. Was expressed.

6. Washing and drying

The etched glass substrates were ultrasonically washed with ethanol and distilled water and then blown with N ₂ gas and dried at 100 ° C. for 10 minutes in a drier.

In the present invention, both a polishing process and an etching process for glass are performed, and both etching and polishing correspond to a process for removing flaw present in the glass substrate. However, the two processes have obvious differences, and the features of the present invention exist in recognizing these differences and in introducing and applying the etching and polishing processes, respectively. The polishing process is to remove cracks and flaws at the edges of the glass substrate, and the etching is carried out for the purpose of removing flaws on the surface. The breakdown of the glass by impact propagates from where the crack is and basically starts from the surface. Therefore, the purpose of polishing and etching are both flaw removal, but the difference is that the flaw does not target the same flaw. In addition, the effect of increasing the strength value by polishing the edges through the polishing process and further reinforcing the increase of the strength value through etching are not known at all in the ordinary glass processing process and are not applied in the general field. Given its industrial reality as a process, the performance of these two processes ultimately results in a significant increase in the strength value of the glass substrate. Therefore, the introduction of such a process forms one of the core ideas of the present invention. As described later, the etching method also serves to maintain sufficient light transmittance so as not to be contrary to the use of the glass for display even after the ion exchange process for the antibacterial treatment is completed.

By removing the surface flaw of the glass substrate by performing both such polishing and etching processes, it is possible to finely adjust the strength value according to the precise adjustment of the ion exchange schedule described later, and to remove the flaw which is the cause of the undesired strength decrease value. The strength value of the glass substrate can be reproducibly implemented. It should be taken into account that the reproducibility of these intensity values is of great importance in the process according to the invention.

<Ion exchange>

The present invention aims to maximize the strength of the glass substrate and to maintain or improve the light transmittance from the combination process of the etching process and the ion exchange process. In this process, both the etching process and the ion exchange process, With the simplification of the process progress method and the process system in mind, it is therefore aimed to produce a glass substrate having excellent strength and light transmittance while being suitable for mass production processes. Furthermore, it is also a core idea of the present invention to impart antimicrobial properties of the glass substrate through the ion exchange process as a concept of the expansion of the ion exchange process. In addition, the process by ion exchange strengthening was adopted as it is in view of the economical efficiency of the process. Therefore, the strengthening process by etching and ion exchange and the antimicrobial characterization of the glass by ion exchange should be regarded as specific features of the invention, respectively.

In the present invention, the respective inventive features were examined by separately performing an ion exchange process for strengthening the glass substrate by ion exchange or an antibacterial treatment of the glass substrate. In addition, by performing the above two processes in a combination of the various forms, the effect of one process on the other will be examined.

In order to reinforce the glass substrate by the ion exchange method, the glass substrate was embedded in the powder in a state in which KNO ₃ powder was accommodated in an alumina square tray as a solid phase coating method. The lower surface was strengthened. At this time, the KNO ₃ powder was applied to both sides of the glass substrate by 20g, and then glass tempering was performed by the ion exchange method under the following temperature conditions. However, the coating amount of the KNO ₃ powder is not limited as described above, and in this embodiment, the powder is applied once and the entire amount of the powder is discarded after ion exchange is completed. This also applies to the following AgNO ₃ powder.

In addition, KNO ₃ , AgNO _3, etc., which are not the solid phase coating method, may be prepared in a liquid phase, and ion exchange may be performed by a liquid coating method for coating the surface of the glass. Such a liquid coating method, for example, may be prepared by preparing a sol for KNO ₃ , AgNO _3, etc., coating it on a glass surface, and performing ion exchange according to an ion exchange temperature schedule. However, this method of coating is for the state of the material to be applied, and the resulting physical properties are about the same, so the following specific ion exchange process will mainly describe the solid phase coating method.

On the other hand, antibacterial glass was prepared separately or together with strengthening by ion exchange, and after placing the glass substrate in an alumina square tray for antimicrobial test through the production of antibacterial glass, AgNO ₃ powder was placed on the upper surface of the placed glass substrate. The cross-coating was performed by 10 g each to carry out an ion exchange process.

Here, AgNO ₃ was used as a starting material for the purpose of specifically selecting Ag as a material exhibiting antimicrobial properties, but it is not limited to AgNO ₃ , and all possible Ag salts will be targeted as starting materials. . In addition, in order to exhibit antimicrobial properties, it may be used in place of Cu salts, and Cu (NO ₃ ) ₂ may be used corresponding to AgNO ₃ . For reference, Cu (NO ₃ ) ₂ is more advantageous than AgNO _{3 in terms of} manufacturing cost. However, since the ion exchange process and the ion exchange mechanism are almost similar for both Ag and Cu, the experiment and result data for Cu ion exchange are replaced by the experiment and result data for Ag ion exchange.

On the other hand, in the manufacturing process of the antimicrobial glass according to the present invention, in particular, the use of the application method (including solid, liquid) can be described from the following contents. Among the materials used for antibacterial treatment, for example, when Ag ions are ion-exchanged by the molten salt method, it is difficult to coat only one surface of the glass of the touch screen by ion-exchanging the entire glass. Since the other side of the display glass is located on the opposite side of the touch surface, it is derived from the technical idea that the antibacterial treatment is not necessary. Therefore, when the coating method is used, since only one side of the display glass can be treated with antibacterial, the process economy becomes more advantageous. However, it should not be limited to antibacterial treatment on only one side.

Looking at the process, the ion exchange by the coating method is the melting point (KNO ₃ : 334 ℃, AgNO ₃ : 212 ℃, Cu (NO ₃ ) ₂ : KNO ₃ for reinforcement, AgNO ₃ for antibacterial activity, Cu (NO ₃ ) ₂ powder): It is ion exchanged by diffusion process by applying heat up to around 256 ℃). Even if a large amount of powder is applied to one side, the glass sinks and covers the glass substrate when melting the powder. Exchanged. Therefore, in the case of ion exchange tempered glass coated with only one side to give antimicrobial activity, after the powder is applied in the alumina square tray, the fixed plates are placed at both ends of the glass (not shown), so that the glass sinks after powder melting and ion exchanged on both sides. It can be prevented. That is, such an application method is much easier to antibacterial treatment on only one surface than the ion exchange method by the melting method. However, exactly one side of the antibacterial glass is prepared by KNO ₃ , AgNO ₃ for antibacterial and Cu (NO ₃ ) ₂ as a solution containing a sol form and coated on one side of the glass substrate using a spin coater. Can be obtained by heat treatment.

In addition, if ion exchange is applied not only through Ag + ions but also Cu + ions with low raw materials, the ion exchange can be selectively performed on one side after strengthening. 100% antimicrobial activity against bacteria such as aureus. In particular, by dividing into 1min, 5min, 60min, etc., it is possible to secure the price competitiveness by securing the optimal conditions of ion exchange which shows antimicrobial effect in a short time. This will be described later.

In performing the ion exchange process for the strengthening or antibacterial treatment, the ion exchange temperature, the ion exchange heat treatment schedule and the ion exchange time were considered as the main variables. This will also be described later.

More specific ion exchange process and evaluation of the ion exchanged glass can be described as follows.

-First, using KNO ₃ powder was heat-treated for 0 to 30 minutes at 420 ~ 480 ℃, and then compared to the parent glass substrate and physical properties.

-KNO ₃ second After mixing the powder and AgNO ₃ powder in a certain mol%, after 15 minutes ion exchange at 450 ℃ to check the mechanical properties, antibacterial and light transmittance.

-Third, KNO ₃ powder was ion exchanged at 450 ° C. for 15 minutes and AgNO ₃ powder was ion exchanged at 240 to 280 ° C. for 1 to 10 minutes to confirm mechanical properties, antimicrobial activity and light transmittance. Meanwhile, when Cu (NO ₃ ) ₂ powder is used instead of AgNO ₃ powder, the ion exchange temperature may be lowered to about 225 ° C. on the basis of the commercially available temperature as the display glass.

Here, this process was not performed for the ion exchange process using AgNO ₃ powder independently, but the antimicrobial characteristics did not change due to the antimicrobial treatment process in parallel with the reinforcement process. It is enough to figure out. This antimicrobial property will be described later.

This ion exchange process is summarized in Table 2 below.

Powder Ion exchange conditions KNO ₃ Powder 420 ~ 480 ℃, 0 ~ 30 min KNO ₃ : AgNO ₃ powder mixing 450 ° C., 15 min
0.01 to 100 mol% AgNO ₃ KNO ₃ ion exchange
AgNO ₃ powder KNO ₃ : 450 ℃, 15 min
AgNO ₃ : 240 ~ 280 ℃, 1 ~ 10 min

In addition, the properties of the salt used for ion exchange in the present invention are summarized as shown in Table 3 below.

type Potassium nitrate Silver nitrate Molecular formula KNO ₃ AgNO ₃ M.P. 334 ℃ 212 ℃ B.P. 400 ° C 444 ℃ Solubility in water 216kg / L (20 ℃) 0.36kg / L (20 ℃) density 2.11 g / cm3 (16 ° C) 4.35 g / cm3 (16 ° C)

In addition, the ion exchange conditions carried out by way of example in the present invention are shown in FIG. 2. (a) shows a heat treatment schedule required for strengthening the glass substrate by ion exchange, and (b) shows a heat treatment schedule necessary for imparting antimicrobial properties of the glass substrate by ion exchange.

As shown, the temperature increase rate required to reach the ion exchange temperature was set to 5 ℃, 10 ℃, 20 ℃ value per minute, and experimentally derived that it is desirable to maintain the preferable temperature increase rate at a value of 8 ~ 15 ℃ per minute Could. At this time, the light transmittance was 90 to 93% based on the glass subjected to the etching treatment, the strength was able to produce a glass having a value of 650 ~ 700MPa.

Faster heating rate means faster passage through the non-target temperature, which would mean reducing ion exchange time at a temperature other than the target temperature during heating. Similarly, slowing the rate of heating may be thought to further increase the ion exchange time at other temperatures during the heating.

Therefore, the temperature raising rate schedule is an important factor in ion exchange. Since the strengthening by ion exchange is the result of K + ions forming a compressive stress on the glass surface, the temperature increase rate is increased so that K + ions move toward the inside of the surface. Not digging too deeply has a better effect on reinforcement. However, if the temperature rises too fast, it can be considered that K + ions do not exchange sufficiently on the glass surface, so it can be concluded that scheduling an appropriate temperature rise will produce good results.

In addition, if the temperature rise rate is changed, the degree of ion exchange occurs while the temperature rises toward the target temperature, that is, the depth and amount of ions penetrated are changed, which means that the position of the compressive stress layer The amount will be determined, which will ultimately affect the strength properties, so the rate of temperature increase is a very important factor. That is, the range of temperature rise rate above has a critical meaning in relation to the depth of penetration of ions.

In addition, the ion exchange progress temperature according to the present invention is preferably 440 to 460 ° C. Such a temperature range would mean purely ion exchange at this temperature. In practice, however, as the temperature rises, it does not matter much at low temperatures, but closer to the temperatures mentioned above, ion exchange will occur at slightly lower temperatures, not 440 to 460 ° C. In other words, it should be seen that some degree of ion exchange takes place at temperatures close to 440 to 460 ° C. both during the temperature rise and during the temperature drop.

Therefore, the present invention can be carried out by adjusting the temperature range of 440 ~ 460 ℃ and the temperature increase rate of 8 ~ 15 ℃ per minute, experimentally such a numerical range makes the meaning of the present invention. This is because the heat treatment schedule can derive the preferable light transmittance and intensity values as described above.

Such critical ion exchange temperature and temperature increase rate can be derived from the critical significance, which will be described in the evaluation of the reinforced or antimicrobial glass produced by the present invention as described below.

<Evaluation of reinforcing and antibacterial properties by ion exchange>

Through the ion exchange process carried out as described above, the properties of the glass substrate given the strengthening and antimicrobial properties were evaluated, and the items used for evaluation items, evaluation purposes and evaluation are shown in Table 4 below.

Evaluation item Purpose of Evaluation Equipment used burglar Bending Strength (R.T): KS L 1591 Bending strength tester
(H-10K, Hounsfield, UK) Hardness Hardness of Coating Film Surface: KS L 1603 Vickers Microhardness Tester (MXD-CX3E, Matsuzawa, Japan) Fracture toughness Fracture Toughness by Measuring Crack Length Around Indentation: KS L 1600 Vickers Microhardness Tester (MXD-CX3E, Matsuzawa, Japan) Light transmittance Measurement of transmittance by ion exchange (visible light range: 370 ~ 800nm) UV / Vis. / NIR spectrometer
(Jasco, V-570, Japan) Ion penetration depth K ⁺ , Ag ⁺ penetration depth by ion exchange Electron probe micro analyzer
(JXA-8900R, JEOL, Japan) Microstructure Microstructure of Ion Exchange Interface Scanning electron microscope (SEM, Hitachi S-3000M, Japan) Antimicrobial test Review of antimicrobial activity against used bacteria: ISO 22196 Film adhesion type (used strain: Salmonella, Escherichia coli, etc.)

1. Measurement of mechanical properties

end. Strength

In order to determine the strength of the glass, a three-point bending strength was measured using a universal testing machine (UTM), Hounsfield Test Equipment, Ltd. UK. Specimens for strength measurements were made with a size of 3 × 0.7 × 3.6mm and the number of strength measurements was 10 times.

In looking at the strength characteristics of the glass substrate according to the present invention, comparative data were needed.

To this end, in the drop ball tester after the ion exchange strengthening according to the present invention to convert the required strength according to the drop height of the ball (ball) of 130g in units of MPa was used as comparison data, it is shown in Table 5 below. The conversion method is potential energy (E _p = mgh) was converted into N units and calculated by the following bending strength formula.

σ = 3PL / 2wt ²

σ: 3-fold bending strength

P: Maximum load of the test piece (N)

L: External Spacing (40mm)

w: width of test piece (3mm)

t: thickness of test piece (0.7mm)

When 130g of steel ball was dropped at 90cm, the three-point bending strength increased to 468 MPa.

Required bending strength (MPa) according to drop ball test conditions Drop ball test Required bending strength (MPa) 130g, 30cm 156 130g, 50cm 260 130g, 80cm 416 130g, 90cm 468

Current methods for evaluating mechanical properties after tempering glass for display include bending strength test and drop ball test. In particular, the drop ball test is used a lot of methods to measure the glass strength of the 0.7mm thickness thin like the display glass. Drop ball test is to check the fracture of tempered glass by dropping 130g steel ball at height of 0.3 ~ 1.0m and convert it to the bending strength (MPa) value, which is widely used in the evaluation of mechanical properties. .

I. Hardness

Hardness was measured a total of 10 times using a Micro hardness tester (MXD-CX3E, Matsuzawa, Japan).

All. Fracture toughness

Fracture toughness was measured based on the above hardness values. The number of times was the same as the number of hardness measurements.

la. result

(1) Mechanical Properties by Ion Exchange Reinforcement of Glass Substrate

In accordance with an embodiment of the present invention by comparing the strength, hardness, fracture toughness values of the glass substrate reinforced by KNO ₃ shown in Table 6 below.

Serial Number Ion Exchange Conditions K + penetration depth (μm, up / down) Strength (MPa) Hardness (Hv) Fracture Toughness (MPa√m) 1-1 450 ℃ / 10 minutes / 1 day 15.7 /- 411 681 1.2287 1-2 450 ℃ / 15 minutes / day 18.9 / 19.4 448 694 1.2364 1-3 450 ℃ / 20 minutes / day 24.9 /- 405 670 1.1988 1-4 420 ℃ / 15 minutes / day 16.1 / 17.0 251 633 1.0119 1-5 450 ℃ / 15 minutes / day 18.9 / 19.4 448 694 1.2364 1-6 480 ℃ / 15 minutes / day 27.8 / 28.6 279 638 0.9900 1-7 450 ℃ / 15 minutes / day 18.9 / 19.4 448 694 1.2364 1-8 450 ℃ / 15 minutes / 7 days 18.7 / 19.1 459 686 1.2341 1-9 450 ℃ / 15 minutes / 14 days 18.6 / 19.0 440 681 1.2328 1-10 450 ° C / 15 minutes / 42 days 17.8 / 18.5 433 677 1.1976 1-11 450 ℃ / 10 minutes / 1 day 15.7 /- 411 681 1.2287 1-12 450 ℃ / 10 minutes / 7 days 15.5 /- 404 678 1.1985

Here, as the ion exchange conditions, the temperature means the ion exchange temperature, the time in minutes means the holding time required for ion exchange, and the time in days means the elapsed time for measuring the decrease in strength with time after the ion exchange. do.

The values in Table 6 above are data measured by ion exchange strengthening in a state in which the glass substrate is not accompanied by an etching process, and strength values are measured at 400 MPa.

This contrasts with the fact that the strength of the ion-exchanged tempered glass at 420 ° C and 480 ° C remains at 200 MPa. Here, optimal ion exchange temperature conditions can be derived.

Therefore, the strength values measured by ion exchange strengthening after the glass substrate further includes the etching process are again shown in Table 7 below. Here, the measured values are values obtained by sampling, etching, and averaging some of the data in Table 6.

Serial Number Ion Exchange Conditions burglar
(MPa) Hardness
(Hv) Fracture toughness
(MPam) 1-13 HCl 0.7 N 30sec,
450/10 minutes / 1 day 704 726 1.2676 1-14 HCl 0.9N 30sec,
450/10 minutes / 1 day 688 745 1.2612 1-15 HCl 0.9N 60sec,
450/10 minutes / 1 day 676 718 1.2554 1-16 NaOH 0.1N 60sec,
450/10 minutes / 1 day 654 703 1.2317

As can be seen from Table 7, the value in the range of about 650 ~ 700MPa is derived, it can be seen that the strength value is significantly increased by the etching of the glass substrate.

Profiles of the distribution in the surface of the strengthened glass substrate of K + ions at the ion exchange conditions corresponding to Table 6 above are shown in FIGS. 3 to 6, respectively.

The graph above shows the surface of the glass substrate subjected to the ion exchange process vertically and finely polished the surface, and then using the Electron Probe Micro Analyzer (JXA-8900R, JEOL, Japan). K +, Ag + according to the change The penetration depth and ion concentration profile of the ions were investigated. For the surface reinforcement of the glass substrate, the concentration of exchange ions (herein, K +), the penetration depth of the exchange ions, and the antimicrobial characteristics of the reinforcement are distributed on the surface of the glass substrate. In order to impart, the distribution relationship according to the penetration depth with the exchanged ions should be investigated to derive the glass substrate having the best reinforcing properties and / or antibacterial properties. This is also related to the light transmittance described later.

At this time, all samples were strengthened by solid-state coating on both sides of the glass substrate, and the upper part of the glass surface in order to determine the ion exchange conditions (ion exchange temperature and time change) at the time of the K + ion penetration depth analysis (EPMA). At 0.5 μm (point interval) with resolution up to 100 μm. After securing the ion exchange condition showing the highest strength value, the whole glass (0 ~ 700㎛) was scanned to determine the penetration depth of both the upper and lower K + ions.

As can be seen from Table 6, the maximum intensity value of 448 MPa was shown when the ion exchange temperature was 450 ° C. and the ion exchange holding time was 15 minutes. In addition, it is known from Table 7 As can be seen, the glass substrate was etched under the same conditions as above, and the ion exchange strengthening resulted in more than 650 MPa.

That is, as can be seen from FIGS. 3 to 6, it can be seen that the strength is improved as the K + is distributed on the surface of the glass and the larger the amount is distributed on the surface. Therefore, when the temperature required for ion exchange is too high or the holding time is too long, the penetration depth of K + becomes deeper from the glass surface, and therefore the concentration of K + distributed on the glass surface is lower, which is undesirable. Of course, the temperature increase rate will also affect the depth of penetration of K + ions, as described above.

In addition, even after a maximum of 42 days had elapsed after ion exchange of the glass substrate surface according to the present invention, the phenomenon of decreasing the strength value of the glass substrate was measured in the range of the error level, and no obvious degradation phenomenon was observed. This supports the fact that they were ion exchanged at temperatures above room temperature and hardly eluted at room temperature.

In general, the ion exchange temperature required to strengthen the glass substrate experimentally can be controlled within the range of 440 ~ 460 ℃, the holding time required for the ion exchange is in the range of 10 minutes to 20 minutes, the desired mechanical properties It may be possible to produce a strengthened glass substrate that retains.

If the ion exchange process is performed outside the upper and lower limit values in the above temperature range, the glass substrate may not have sufficient mechanical properties such as sufficient strength value regardless of the holding time, and it may be out of the upper limit of the above holding time range. In this case, K + ions penetrate too deeply from the glass surface, which may adversely affect the mechanical strength of the glass which has been ion-exchanged and strengthened. If it is outside the lower limit, ion exchange is not sufficient, and thus the glass substrate having a desired strength value. There is a problem that can not be prepared. Thus, the above ion exchange temperature and retention time are of critical significance in the above range.

(2) Strength Characteristics by Enhancing Ion Exchange and Antimicrobial Properties of Glass

Next, the KNO ₃ powder and AgNO ₃ powder are mixed according to one embodiment of the present invention, and the glass substrate is provided with reinforcing and antimicrobial properties by ion exchange using the same (antibacterial activity of serial numbers 2-6 in the table below). Including only the glass substrate imparted) was measured as shown in Table 8 below.

Serial Number Ion Exchange Conditions K + penetration depth (μm, up / down)
Ag + penetration depth (μm, up / down) K + input amount (%, up / down)
Ag + input amount (%, up / down) ion
Exchange surface Strength (MPa) 2-1 450 ° C./15 minutes 18.9 / 23.1
38.6 / 41.3 99.99 / 99.99
0.01 / 0.01 both sides 450.10 2-2 450 ° C./15 minutes 22.5 / 29.7
37.0 / 42.1 99.95 / 99.95
0.05 / 0.05 both sides 437.70 2-3 450 ° C./15 minutes 18.8 / 22.9
44.1 / 56.1 99.50 / 99.50
0.50 / 0.50 both sides 424.00 2-4 450 ° C./15 minutes 17.5 / 18.3
58.4 / 62.3 99.00 / 99.00
1.00 / 1.00 both sides 412.18 2-5 450 ° C./15 minutes 18.5 / 19.2
78.4 / 84.2 95.00 / 95.00
5.00 / 5.00 both sides 402.04 2-6 450 ° C./15 minutes 17.8 / 14.5
85.5 / 122.7 0.00 / 0.00
100.00 / 100.00 both sides 283.04 2-7 450 ° C./15 minutes 17.9 / 30.7
19.1 / 68.0 100.00 / 95.00
0.00 / 5.00 K double side
Ag section 448.20

Here, as the ion exchange conditions, the temperature means the ion exchange temperature, and the time in minutes means the holding time required for the ion exchange, respectively. In the present embodiment, the temperature as the ion exchange condition is the ion exchange temperature necessary for the strengthening. In this embodiment, the effect of Ag + ion exchange on the strengthening rather than the antimicrobial properties of the Ag + ion exchange is to be investigated. Experiments with optimized temperature are omitted.

7 to 9 are graphs showing distributions of K + ions and Ag + ions in the glass substrate surface under ion exchange conditions corresponding to Table 8 above.

As can be seen from Table 8 and FIGS. 7 to 9, compared with the above-described results of performing the ion exchange process using only K +, it was found that the strength of the glass substrate in which K + and Ag + were ion-exchanged at the same time is reduced overall. Can be. This is because the K + ions introduced in the meaning of reinforcement retreat in the depth direction from the surface of the glass substrate by the Ag + ions, that is, the deeper penetration depth of K +. Among them, the mechanical properties of K and Ag powders were changed under the same ion exchange conditions. As a result, the strength of glass ionized under the conditions of KNO ₃ 99.5%, AgNO ₃ 0.5%, KNO ₃ 95%, and AgNO ₃ 5% Was found to be related to K + ion penetration depth. The penetration depth of K + ions was measured to be 17.5 and 17.9, respectively, which is similar to the K + ion penetration depth (18.9) of the optimum ion exchange conditions. Inferences can be made from the fact that they exhibit high mechanical properties.

However, in particular, the antimicrobial properties of the glass for display devices need to be applied only to one surface exposed to the outside. Therefore, both surfaces of the glass substrate are strengthened as shown in the serial number 2-7 of Table 8 above, but only Ag is used on one surface. The ion exchange resulted in a satisfactory level of strength of 448.20 MPa. Therefore, in order to maintain the strength value of the glass substrate by preserving the distribution of K + ions on the glass surface while retaining the antimicrobial properties by Ag + ions, it would be preferable to give the antimicrobial property to only one surface. That is, if Ag + ion penetrates only one side and the penetration of Ag + ion does not affect the K + penetration depth of the other side, it is preferable to penetrate Ag + on both sides in terms of strength value. Since it is also compatible with the object of the present invention, it is very preferable.

In the case of the glass substrate not subjected to the ion exchange strengthening process as shown in the serial number 2-6 of Table 8, the low strength value, but since the ion exchange of Ag does not contribute to the improvement of the strength, comparative data It only makes sense.

In the following items, the glass substrates by ion exchange and the antibacterial treatment by ion exchange were separated. As will be described later, strength and antibacterial treatment were simultaneously performed by mixing powder of potassium and silver materials. The results show that the value is improved.

That is, the problem of ion exchange due to powder mixing is caused by the difference between the melting points of the two salts used during ion exchange. The KNO ₃ melting point is 334 ° C and AgNO ₃ is 212 ° C. When the heat treatment is performed in the process, the penetration depth of Ag + ions becomes deeper when the process is performed separately. In the range of 0.01 to 5wt% of Ag powder, the penetration depth is 38.6 ~ 84.2㎛ and the penetration depth of Ag ions exceeds the penetration depth of K ions. In addition, due to the low melting point, ion exchange is performed first. As described above, Ag ions penetrating deeper and earlier than K interfere with formation of uniform surface compressive stress of K ions, thereby affecting strength. Since it is K ions that determine the strength, it is reasonable to consider that it affects the strength by interfering with the formation of a uniform compressive stress layer of K ions rather than simply infiltrating Ag ions deeply. Therefore, mixed ion exchange should be performed at appropriate optimum conditions.

(3) Strength characteristics when antimicrobial is given after ion exchange strengthening of glass

Next, the glass substrate is strengthened by ion exchange at 450 ° C. for 15 minutes using KNO ₃ powder according to one embodiment of the present invention, and subsequently by ion exchange at various temperatures necessary for ion exchange of Ag + using AgNO ₃ powder. After giving the antimicrobial properties to the glass substrate was measured by the intensity value shown in Table 9 below. In view of the foregoing, it is more preferable that Ag ions penetrate only the cross section of the glass substrate, so that Ag ion penetrates only the cross section. It is to be noted that the present invention has an inventive feature that can very easily implement the process of ion permeation only in cross section.

Serial Number Ag + ion exchange
Condition K + penetration depth (μm, up / down)
Ag + penetration depth (μm, up / down) ion
Exchange surface Strength (MPa) 3-1 240 ℃ / 2 minutes 18.0 / 21.5
0.0 / 0.0 Ag section
K both sides 447.45 3-2 240 ℃ / 5 minutes 17.4 / 19.4
0.0 / 0.0 Ag section
K both sides 457.09 3-3 240 ℃ / 10 minutes 18.8 / 22.9
0.0 / 0.0 Ag section
K both sides 475.48 3-4 250 ℃ / 2 minutes 18.7 / 19.5
0.0 / 0.0 Ag section
K both sides 449.10 3-5 250 ° C / 5 minutes 17.2 / 28.2
0.0 / 0.0 Ag section
K both sides 455.27 3-6 250 ° C / 10 minutes 16.7 / 17.7
0.0 / 3.5 Ag section
K both sides 467.03 3-7 255 ° C / 1 minute 17.2 / 18.5
0.0 / 0.4 Ag section
K both sides 445.10 3-8 260 ℃ / 0min 16.8 / 18.1
0.0 / 0.5 Ag section
K both sides 441.51 3-9 260 ° C / 1 min 17.0 / 17.5
0.0 / 0.8 Ag section
K both sides 449.25

Here, as the ion exchange conditions, the temperature means the ion exchange temperature, and the time in minutes means the holding time required for the ion exchange, respectively. Serial numbers 3-7 to 3-9 in Table 9 were to investigate the strength characteristics of the glass substrate derived from the very short holding time required for ion exchange by the minimum Ag + ion permeation experiment.

10 and 12 show graphs of distributions of K + ions and Ag + ions in the glass substrate surface under ion exchange conditions corresponding to Table 9 above.

After the glass substrate was ion-exchanged at 450 ° C. for 15 minutes using KNO ₃ powder, the Ag + ion permeation amount was confirmed by AgNO ₃ powder according to the ion exchange temperature and time change. As shown in Table 9, the minimum penetration depth was obtained at 255 ° C. / 1 minute. Indicated. Ag + The minimum ion exchangeable temperature of ions was found to be 250 ℃ or more. On the other hand, although not shown, it can also be seen that the minimum ion exchangeable temperature of Cu 2+ ions is about 225 ° C.

As can be seen from Table 9 and FIGS. 10 to 12, penetration of Ag + by ion exchange hardly occurred until the holding time of 240 ° C. and 250 ° C. for 5 minutes. However, it was found that ion exchange by Ag + occurred at a temperature of 250 ° C. for 10 minutes and higher. Note that there was almost no change in the strength value even after the ion exchange with Ag +. Compared with Table 8, the ion exchange with K + and the ion exchange with Ag + are performed simultaneously, or the ion exchange with Ag + is sequentially performed after the ion exchange with K +, or one surface of the glass substrate. It can be seen that the Ag + ion exchange only has a similar level of strength. Therefore, in view of the simplicity of the process, it is advantageous to mix the KNO ₃ and AgNO ₃ to proceed the strengthening and antimicrobial at the same time. At this time, the ion exchange conditions for the antimicrobial treatment will be said to be very preferable in terms of strength to be carried out in the range of more than 0 to 10 minutes in the temperature range of 240 ~ 280 ℃. The above range is critical for implementing such strength values.

In addition, the strength was measured by adding an etching process to the antibacterial treatment and the strengthening process is shown in Table 10 below.

Serial Number Ion Exchange Conditions burglar
(MPa) Hardness
(Hv) Fracture toughness
(MPam) 1-13 HCl 0.7 N 30sec,
450/10 minutes / 1 day 617.2 708 1.1887 1-14 HCl 0.9N 30sec,
450/10 minutes / 1 day 621.7 707 1.1904 1-15 HCl 0.9N 60sec,
450/10 minutes / 1 day 588.3 698 1.1789 1-16 NaOH 0.1N 60sec,
450/10 minutes / 1 day 592.4 695 1.1774

As can be seen from the above table, it can be seen that a value ranging from about 580 to 620 MPa is derived. As shown in Table 7 above, although the strength value is lower than that of the non-antibacterial process, it can be seen that the strength level is maintained by etching to the extent that the strength decrease due to the antibacterial treatment can be buffered. In view of this, the strength effect of etching is very significant.

2. Optical Characterization

In order to investigate the optical properties of the glass by ion exchange, the light transmittance of the specimens before and after ion exchange at 200-800 nm was measured using a UV-VIS-NIR spectrophotometer (V-570, JASCO, Japan). For example, when a glass substrate is used for a display device, such light transmittance is a very important property to be dealt with, and if the light transmittance is reduced due to the strengthening or antimicrobial properties of the glass, there is a significant limit to the use of the display glass. As it can be generated, consideration should be given to the provision of the light transmittance and the strengthening and antibacterial properties of the glass at the same time.

According to the ion exchange conditions disclosed in Tables 6 to 10, the light transmittance was measured for each of the glass substrates treated with reinforcement or antibacterial treatment, and the results are shown in Tables 11 to 14. In particular, Table 14 shows the results of the etching.

Serial Number Ion Exchange Conditions K + penetration depth (μm, up / down) Light transmittance (%) 1-1 450 ℃ / 10 minutes / 1 day 15.7 /- 90.77 1-2 450 ℃ / 15 minutes / day 18.9 / 19.4 90.79 1-3 450 ℃ / 20 minutes / day 24.9 /- 90.58 1-4 420 ℃ / 15 minutes / day 16.1 / 17.0 90.85 1-5 450 ℃ / 15 minutes / day 18.9 / 19.4 90.79 1-6 480 ℃ / 15 minutes / day 27.8 / 28.6 90.65 1-7 450 ℃ / 15 minutes / day 18.9 / 19.4 90.79 1-8 450 ℃ / 15 minutes / 7 days 18.7 / 19.1 90.71 1-9 450 ℃ / 15 minutes / 14 days 18.6 / 19.0 90.81 1-10 450 ° C / 15 minutes / 42 days 17.8 / 18.5 90.72 1-11 450 ℃ / 10 minutes / 1 day 15.7 /- 90.77 1-12 450 ℃ / 10 minutes / 7 days 15.5 /- 90.82

Serial Number Ion Exchange Conditions K + penetration depth (μm, up / down)
Ag + penetration depth (μm, up / down) K + input amount (%, up / down)
Ag + input amount (%, up / down) Light transmittance
(%) 2-1 450 ° C./15 minutes 18.9 / 23.1
38.6 / 41.3 99.99 / 99.99
0.01 / 0.01 91.36 2-2 450 ° C./15 minutes 22.5 / 29.7
37.0 / 42.1 99.95 / 99.95
0.05 / 0.05 88.88 2-3 450 ° C./15 minutes 18.8 / 22.9
44.1 / 56.1 99.50 / 99.50
0.50 / 0.50 85.77 2-4 450 ° C./15 minutes 17.5 / 18.3
58.4 / 62.3 99.00 / 99.00
1.00 / 1.00 82.04 2-5 450 ° C./15 minutes 17.5 / 31.7
0 / 48.5 0.00 / 99.50
0.00 / 0.50 90.63

Serial Number Ag + ion exchange
Condition K + penetration depth (μm, up / down)
Ag + penetration depth (μm, up / down) Light transmittance (%) 3-1 240 ℃ / 2 minutes 18.0 / 21.5
0.0 / 0.0 90.98 3-2 240 ℃ / 5 minutes 17.4 / 19.4
0.0 / 0.0 90.89 3-3 240 ℃ / 10 minutes 18.8 / 22.9
0.0 / 0.0 90.95 3-4 250 ℃ / 2 minutes 18.7 / 19.5
0.0 / 0.0 90.82 3-5 250 ° C / 5 minutes 17.2 / 28.2
0.0 / 0.0 90.94 3-6 250 ° C / 10 minutes 16.7 / 17.7
0.0 / 3.5 90.70 3-7 255 ° C / 1 minute 17.2 / 18.5
0.0 / 0.4 90.75 3-8 260 ℃ / 0min 16.8 / 18.1
0.0 / 0.5 90.71 3-9 260 ° C / 1 min 17.0 / 17.5
0.0 / 0.8 90.63

As can be seen from Tables 11 to 13 above, although the value was slightly lower in the strengthening process of the glass substrate by ion exchange, it corresponds to 91.83% of the transmittance of the mother glass and very different, KNO ₃ and AgNO ₃ In the case of mixing and ion-exchanging, it can be seen that as the amount of exchange of Ag + ions increases, the light transmittance decreases significantly. However, when only one surface of the glass substrate is strengthened and antibacterial, and ion exchange is applied to both surfaces of the glass substrate, the total amount of K + ions and Ag + ions is 100%. When the amount was 0.05% or less, light transmittance close to the mother glass could be obtained. In addition, in the step of imparting antimicrobial properties after ion strengthening, the light transmittance close to the light transmittance of the mother glass can be obtained by giving the antibacterial treatment to the end surface. In this case, however, the penetration depth of Ag + was very small.

On the other hand, when Ag + ions were infiltrated at temperatures of 250, 255, 260, 270, and 280 ° C, the penetration rates were 0.35, 0.40, 0.80, 0.98, 1.20 / min, which was 260 ° C, indicating the ion exchange antimicrobial activity of Ag +. In case of 1min ion exchange, Ag means 0.8 per minute penetration into the glass surface, and it is a condition for producing antimicrobial glass with little decrease in light transmittance. On the other hand, although not shown, in the case of Cu2 +, ion exchange at 225 ℃ and 230 ℃, showed an antimicrobial effect without lowering the light transmittance, as described above.

In addition, when the ion exchange holding time was maintained within 10 minutes, the antimicrobial effect and the ion penetration depth of Ag + in Table 13 were obtained.

From this, the ion exchange conditions that can maintain the light transmittance at a commercially available level, when the temperature range of 225 ~ 270 ℃ and ion exchange time conditions of less than 0 seconds and 10 minutes or less, the present invention can be optimized.

Therefore, at 450 and 15 minutes, which is the optimal ion exchange strengthening condition, it is possible to selectively manufacture multifunctional (antibacterial, tempered, light transmittance) tempered glass when ion exchanged with an antimicrobial effect and a minimum penetration depth of Ag ions. can do.

Thus, in the case where both etching, antibacterial treatment, and reinforcement were performed, an attempt was made to determine the degree of improvement in light transmittance, which is shown in Table 14 below.

Serial Number Ion Exchange Conditions Light transmittance (%) 4-1 HCl 0.7 N 30sec,
450/10 minutes / 1 day 91.18 4-2 HCl 0.9N 30sec,
450/10 minutes / 1 day 91.67 4-3 HCl 0.9N 60sec,
450/10 minutes / 1 day 91.32 4-4 NaOH 0.1N 60sec,
450/10 minutes / 1 day 90.91

As can be seen from the above table, light transmittance values ranging from about 90 to 92% were derived, and light transmittances were measured around 91%. From this, it can be seen that the light transmittance was reduced after ion exchange compared to the mother glass, but it was recovered again by the etching process. Therefore, the etching process is meaningful in that it improves light transmittance.

13 and 14 show the light transmittance as a result of etching in NaOH solution.

If the above is about light transmittance before etching, the depicted shows the light transmittance after strengthening of the etched glass substrate. As shown, it can be seen that the light transmittance exhibits a light transmittance in the range of 90 to 94% improved over the light transmittance of the mother glass. Therefore, it can be said that the etching of the present invention corresponds to a process capable of realizing excellent light transmittance as glass applications for displays.

3. Antimicrobial Evaluation

15 and 16 show the results of the evaluation of the antimicrobial activity of the glass substrate imparted by the present invention. Antimicrobial evaluation was evaluated by analyzing the antimicrobial activity (log) of the ion exchanged glass substrates for salmonella typhimurium bacteria (FIG. 15) and E-coli bacteria (FIG. 16) by a film adhesion method according to ISO 22196. More specifically, sallmonella typhimurium and E-coli bacteria were put in petri dish, respectively, and cultured in 37 incubators for 24 hours, and then the antimicrobial activity was evaluated by checking the antimicrobial activity against ion exchange glass. As a result, it was shown that the antibacterial activity of the glass ion-exchanged for Ag 260 ° C., 1 min, and Cu 230 ° C., 1 min, which was tested separately, was 100%, respectively.

In addition, the antimicrobial evaluation of the glass substrate to which the antimicrobial properties are imparted according to the present invention is shown in FIG. 15 and 16 will be referred to as the result with reinforcement, Figure 17 will be referred to as a result without reinforcement. In this case, the solid-state coating method is used, respectively, and the antimicrobial activity is exhibited when exposed to Staphylococcus aureus for 1 minute as a result of Ag and Cu ion exchange under the above-described ion exchange conditions. As shown, the antimicrobial activity of each glass was found to be close to 100%.

Here, the above results are intended to show the same results as the antimicrobial treatment with glass strengthening or antimicrobial treatment without strengthening. In other words, despite the reinforcement, the antimicrobial performance did not decrease at all.

Although not shown in the other experimental results, it can be seen that the antimicrobial activity of 99% or more by the ion-treated antibacterial glass in the range of 240 ~ 280 ℃.

Claims (12)

Etching at least one surface of the glass substrate to remove oxide films and microcracks on the surface of the glass substrate to primarily strengthen the glass substrate;
And secondly strengthening the glass substrate by ion exchange by contacting or applying a potassium-based material to at least one etched surface of the glass substrate.
The second step of strengthening the glass substrate is to strengthen the glass substrate for the display, characterized in that at the same time to give a further antimicrobial to the glass substrate by further mixing silver or silver salt or copper-based material to the potassium-based material Ion exchange method. The method of claim 1,
The ion exchange method for strengthening the glass for display, characterized in that the glass having a light transmittance value of 90 ~ 93% as a result of removing the oxide film and microcracks through the etching. The method of claim 1,
The potassium-based material is an ion exchange method for strengthening the glass for display, characterized in that the solution containing a powder, pulverized powder, sol (sol) of potassium nitrate. The method of claim 1,
In the ion exchange step, the heating rate is 8 to 15 ℃ per minute in the temperature increase to the ion exchange temperature, and the heating process including a heating history to maintain for 10 to 20 minutes at a temperature of 440 ~ 460 ℃ Ion exchange method for strengthening the display glass. delete The method of claim 1,
After the second step of strengthening the glass substrate, further comprising the step of ion exchange by contacting or applying silver or silver salts or copper-based material to impart antimicrobial properties to the glass substrate, characterized in that it further comprises Ion exchange method for treatment. The method according to claim 6,
In the step of imparting antimicrobial activity, the heating rate is 8 to 15 ° C. per minute when the temperature is raised to the ion exchange temperature, and a heating history of applying a holding time of more than 0 minutes and 10 minutes or less at a temperature of 240 to 280 ° C. Ion exchange method for strengthening and antibacterial treatment of the display glass, characterized in that the heating process. 7. The method according to claim 1 or 6,
Ion exchange method for strengthening and antimicrobial treatment of the display glass, characterized in that the contact or coating the silver or copper-based material on only one surface of the glass substrate. 7. The method according to claim 1 or 6,
Ion exchange is applied to both surfaces of the glass substrate, but the relative amount of silver or silver salt or copper-based material relative to the potassium-based material is greater than 0 and 0.05% or less for the strengthening and antibacterial treatment of the glass for display. 7. The method according to claim 1 or 6,
The silver salt and the copper-based material is a powder, a pulverized product or a solution of silver nitrate and copper nitrate, respectively. delete An antimicrobial glass for display reinforced by ion exchange, which is prepared by the method of claim 1 or 6 and has a light transmittance of 90 to 92% and an intensity value of 580 to 620 MPa.

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