KR102201846B1 - Composition for manufacturing tempered glass and method for manufacturing tempered glass - Google Patents

Abstract

According to an embodiment of the present invention, the first potassium salt; And a second potassium salt different from the first potassium salt, wherein the first potassium salt is a potassium nitrate salt (KNO ₃ ), the second potassium salt is a low specific gravity potassium salt having a specific gravity of 1.4 to 2.0, the The second potassium salt is provided with a composition for preparing a tempered glass, which is contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the total composition.

Description

A composition for manufacturing a tempered glass, and a method for manufacturing a tempered glass TECHNICAL FIELD TECHNICAL FIELD The composition for manufacturing a tempered glass and a method for manufacturing a tempered glass TECHNICAL FIELD

The present invention relates to a composition for producing a tempered glass and a method for producing a tempered glass, and to a composition for producing a tempered glass and a method for producing a tempered glass capable of improving ion exchange rate by increasing ion fluidity.

Recently, as a glass panel is required to be lighter and thinner to reduce thickness and weight, research on a reinforcing method capable of supplementing structural weaknesses is being actively conducted.

In particular, as UTG (Ultra Thin Glass) applicable to foldable smartphones is being manufactured, the need for glass reinforcement technology is further required.

However, in the case of the glass reinforcing technology using the existing high specific gravity potassium nitrate (KNO ₃ ) dissolved salt, there has been a problem in that the productivity and quality uniformity of the tempered glass are poor due to the slow ion exchange rate.

Accordingly, the need for a technology for manufacturing a tempered glass to improve ion exchange rate by increasing ion fluidity is further raised.

An object of the present invention is to provide a composition for producing a tempered glass capable of improving the productivity, yield, and quality uniformity of the tempered glass by increasing ion fluidity to improve the ion exchange rate.

In addition, an object of the present invention is to prepare a tempered glass capable of preventing breakage of the glass and improving impact resistance by controlling the compressive stress and ion penetration depth of the glass, respectively, by separating the reinforcing steps under different conditions. In providing a way.

The composition for manufacturing a tempered glass according to an embodiment of the present invention includes a first potassium salt; And a second potassium salt different from the first potassium salt, and the first potassium salt contains 1 to 30 parts by weight having a specific gravity higher than 2.0. It is a high specific gravity potassium salt, the second potassium salt is a low specific gravity potassium salt having a specific gravity of 1.4 to 2.0, and the second potassium salt is based on 100 parts by weight of the total composition.

In one embodiment of the present invention, the low specific gravity potassium salt is potassium formate (Potassium Formate), potassium oxalate (Potassium Oxalate), potassium acetate (Potassium Acetate), potassium methoxide , Potassium Ethoxide, and Potassium bicarbonate potassium salt.

In one embodiment of the present invention, the composition for preparing a tempered glass is provided at a temperature of 300°C to 550°C.

Tempered glass manufacturing method according to an embodiment of the present invention, a first tempered step of immersing the glass in the composition for producing a first tempered glass in a first temperature range; And a second reinforcing step of immersing the glass in the composition for producing a second tempered glass in a second temperature range different from the first temperature range, wherein each of the composition for producing the first tempered glass and the composition for producing the second tempered glass is a first potassium salt ; And a second potassium salt different from the first potassium salt, wherein the first potassium salt is a high specific gravity potassium salt having a specific gravity higher than 2.0, and the second potassium salt is provided as a low specific gravity potassium salt having a specific gravity of 1.4 to 2.0. do.

In an embodiment of the present invention, the first strengthening step is performed at a temperature of 450°C to 550°C.

In one embodiment of the present invention, the second strengthening step is performed at a lower temperature than the first strengthening step.

In one embodiment of the present invention, the second strengthening step is performed at a temperature of 300°C to 500°C.

In one embodiment of the present invention, the content of the second potassium salt in the composition for producing the first tempered glass and the content of the second potassium salt in the composition for producing the second tempered glass are provided differently from each other.

In one embodiment of the present invention, the content of the second potassium salt in the composition for producing the second tempered glass is provided lower than the content of the second potassium salt in the composition for producing the first tempered glass.

In one embodiment of the present invention, the low specific gravity potassium salt is potassium formate (Potassium Formate), potassium oxalate (Potassium Oxalate), potassium acetate (Potassium Acetate), potassium methoxide , Potassium Ethoxide, and Potassium bicarbonate potassium salt.

When the composition for manufacturing a tempered glass and a method for manufacturing a tempered glass according to an embodiment of the present invention are used, the ion exchange rate is improved by increasing ion fluidity, thereby improving the productivity, yield, and quality uniformity of the tempered glass. There is.

In addition, by separating the reinforcing steps under different conditions, by respectively adjusting the compressive stress and the ion penetration depth of the glass, there is an effect of preventing breakage of the glass and improving the impact resistance.

1 is a flow chart of a method for manufacturing a tempered glass according to an embodiment of the present invention.
2 is a cross-sectional view showing a tempered glass manufactured through a method for manufacturing a tempered glass according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In describing the present invention, when it is determined that a spherical description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In addition, the advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described later in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims.

In general, the method of manufacturing tempered glass is divided into physical strengthening and chemical strengthening.

Physical reinforcement is a method of reinforcing the internal strength of the glass by heating the glass at a temperature between about 550°C and about 700°C and rapidly cooling it. When heat is applied, natural strengthening is achieved as the temperature gradient inside the glass is gently formed. .

The physical reinforcement method is generally used for glass with a thickness of 1 mm or more, and is mainly used for tempered glass doors and automobile glass.

On the other hand, in the case of ultra-thin glass, since it has a thin thickness that is difficult to form a smooth temperature gradient inside, a phenomenon that is easily broken occurs when heat above a certain temperature is applied. Therefore, in the case of ultra-thin glass, it is common to use chemical strengthening.

Chemical strengthening is a technique of forming a chemical strengthening layer (compressive stress layer) in which surface compressive stress remains by contacting glass with an inorganic salt to induce mutual ion exchange with the inorganic salt on the surface of the glass.

For example, alkali metal ions with a small ionic radius on the surface of a glass plate (typically Li ⁺ ions, Na ⁺ ions) are converted to alkali ions with a larger ionic radius (typically Na ⁺ ions or K ⁺ ions for Li ⁺ ions). and, by substituting the K ⁺ ion) for the Na ⁺ ion, and a compressive stress remains on the surface of the glass, thus improving the strength of glass.

As a method of bringing the inorganic salt into contact with glass, there are a dry ion exchange method and a wet ion exchange method.

The dry ion exchange method is carried out by applying, spraying, or depositing a coating liquid or paste containing a salt on a glass surface.

In the case of the wet ion exchange method, it is carried out by immersing the glass in a salt bath containing a molten salt to supply ions to the glass. The ion exchange process between the glass surface and the molten salt is achieved by the penetration of ions into the glass immersed in the salt bath in an elevated temperature atmosphere by diffusion due to the difference in concentration.

The composition for producing tempered glass and the method for producing tempered glass of the present invention can be particularly applied to a wet ion exchange method.

Hereinafter, a composition for manufacturing a tempered glass according to an embodiment of the present invention used in a wet ion exchange method will be described.

The composition for manufacturing a tempered glass according to an embodiment of the present invention may include a first potassium salt and a second potassium salt different from the first potassium salt.

The first potassium salt may be a high specific gravity potassium salt. For example, the first potassium salt may be a potassium nitrate salt (KNO ₃ ). The potassium nitrate salt (KNO ₃ ) is the most common potassium source solution used for chemical strengthening of an immersion method, and may have a specific gravity of about 2.11.

The first potassium salt is potassium hydroxide phosphate (K ₂ HPO ₄ ), potassium chloride (KCl), potassium phosphate (K ₂ PO ₄ ), potassium sulfate (K ₂ SO ₄ ), potassium hydroxide (KOH) or potassium chromate (K _{2 ).} CrO ₄ ) and the like, and in addition, any potassium salt having a specific gravity of more than about 2.0 can be used as the first potassium salt.

The second potassium salt may be a low specific gravity potassium salt. The low specific gravity potassium salt is a potassium source solution having a relatively smaller specific gravity than the potassium nitrate salt (KNO ₃ ), and may be a potassium salt having a specific gravity of about 1.4 to about 2.0.

Low specific gravity potassium salts include: Potassium Formate, Potassium Oxalate, Potassium Acetate, Potassium Methoxide, and Potassium Ethoxide. , And Potassium bicarbonate (Potassium bicarbonate) may include at least one or more of a potassium salt.

The low specific gravity potassium salt is not limited to the above types, and any potassium salt having a specific gravity of about 1.4 to about 2.0 may be used.

Low specific gravity potassium salt has a smaller specific gravity and lighter characteristics than high specific gravity potassium salt. Accordingly, in the case of the composition for preparing a tempered glass of the present invention containing a low specific gravity potassium salt, gas is actively generated at a high temperature, and by improving the fluidity of ions in the composition for producing a tempered glass, the diffusion rate of ions can be improved. have. For this reason, there is an advantage of improving the productivity of the tempered glass, and there is an effect of improving the uniformity of quality on the surface of the tempered glass.

In addition, in the case of the conventional case, despite the demand to simultaneously improve the depth of penetration (DOL) and compressive stress, only the time and temperature variables are controlled, so that when the temperature of the molten salt increases, the ion penetration depth increases. However, there is a problem that the compressive stress is rather reduced.

However, the composition for producing a tempered glass of the present invention has the advantage of lowering the melting point and increasing the activation energy at the same temperature as the low specific gravity potassium salt is included. For this reason, since the ions to be exchanged can penetrate deeper through the glass surface, there is an effect of further improving ion permeability from the surface.

In addition, in the case of a low specific gravity potassium salt, since the glass transition temperature is relatively low compared to other high specific gravity potassium salts, there is an advantage of relatively easy temperature control during the tempering treatment. In addition, since the low specific gravity potassium salt is formed with a low boiling point, the gas generation effect is large even at a relatively low temperature, so that diffusion between ions is easy.

The second potassium salt may be included in an amount of about 1 part by weight to about 30 parts by weight based on 100 parts by weight of the total composition. When the second potassium salt is included in less than about 1 part by weight, the ion diffusion effect by the second potassium salt may be insignificant. In addition, when the second potassium salt is included in an amount greater than about 30 parts by weight, a relatively large amount of energy may be used as the phase shift energy of the second potassium salt in the process, and thus a high process temperature may be required. When the process temperature becomes high, there is a high possibility that the glass will be damaged in the glass reinforcing process. In addition, when the ratio of the second potassium salt is high, the manufacturing cost of the composition for manufacturing a tempered glass may be too high.

The composition for manufacturing a tempered glass of the present invention may be composed of only the low specific gravity potassium salt, but in the case of the low specific gravity potassium salt, there is a problem that the cost of the product is increased because the price is high. Accordingly, when a composition for preparing a tempered glass is prepared by mixing a relatively inexpensive high specific gravity potassium nitrate salt (KNO ₃ ), there is an advantage of lowering the production cost.

Hereinafter, a method of manufacturing a tempered glass using the composition for manufacturing a tempered glass of the present invention will be described.

1 is a flow chart showing a method of manufacturing a tempered glass according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing a tempered glass includes a first tempered step (S100) of immersing the glass in a composition for producing a first tempered glass in a first temperature range.

In the first strengthening step (S100), by immersing the glass in the composition for preparing the first strengthened glass, sodium ions in the glass are mutually substituted with potassium ions, and the strength of the glass may be increased.

The first strengthening step S100 may be performed at a temperature of about 450° C. to about 550° C. for about 2 hours to about 20 hours.

In this case, the tempering temperature is preferably performed at or below the glass transition temperature. When the strengthening temperature exceeds the glass transition temperature, deformation and distortion occur, and it becomes impossible to form a strengthening layer by forming stress between ions in the glass.

The tempering temperature and time are not limited to the above, and may be appropriately adjusted according to the size, thickness, and sodium content of the glass.

For example, a glass having a thickness of about 0.4mm may be immersed for about 3 hours, and a glass having a thickness of about 0.7mm may be immersed for about 4 hours.

When chemical strengthening such as the first strengthening step (S100) is performed, the chemical composition of the glass surface layer is different from before the chemical strengthening. The chemical composition of the surface layer gradually changes from the surface layer of the glass to the inner layer, and properties of the glass such as ion fluidity and electrical conductivity also change from the surface layer to the inner layer of the glass.

In addition, the electrical conductivity of the glass surface layer varies depending on the chemical composition of the glass, which has a strong influence on the resistance of the glass to electrical breakdown. At this time, the lower the fluidity of the ions contained in the glass surface layer, the lower the electrical conductivity and the higher the strength of the glass.

Therefore, in order to lower the ionic fluidity of the glass surface layer, it is possible to reduce the ionic fluidity of the glass surface layer by substituting ions of a small size with ions of a large size having a lower fluidity. The degree of this decrease in ion mobility depends on the type and concentration of ions participating in the ion exchange process.

In the case of the present invention, glass reinforcement can be performed by immersing the glass in a composition for preparing a tempered glass containing a first potassium salt and a second potassium salt. At this time, the first potassium salt may be a high specific gravity potassium salt having a specific gravity higher than 2.0, and the second potassium salt may be a low specific gravity potassium salt having a specific gravity of about 1.4 to about 2.0. When the glass is immersed in the composition for making tempered glass, small Na ⁺ ions (atomic size 0.98 Å) diffuse out of the glass, and large K ⁺ ions (atomic size 1.33 Å) are in the place where Na ⁺ ions exist. Will penetrate.

That is, since K ⁺ ions occupy more space than Na ⁺ ions, as the glass is cooled, pressure is applied to each other, resulting in compressive stress, and a tempered glass having a large surface density is formed. This compressive stress layer (reinforcement layer) can prevent the occurrence of cracks and scratches in the interior or surface of the glass.

The second strengthening step (S200) is performed after the first strengthening step (S100), and is a step of chemical strengthening at a temperature different from that of the first strengthening step (S100).

The second strengthening step (S200) may be performed at a temperature of about 300°C to about 500°C.

The second strengthening step is performed to independently control the ion penetration depth in each step by setting the strengthening environmental conditions different from each other from the first strengthening step S100.

Accordingly, compared to the case of performing only the first reinforcing step (S100), since it is possible to more precisely control the ion penetration depth, there is an advantage in that a stress layer of uniform and excellent quality can be formed.

In an embodiment, the second strengthening step S200 may be performed at a lower temperature than the first strengthening step S100.

For example, the first strengthening step S100 may be performed at a temperature of about 500°C, and the second strengthening step S200 may be performed at a temperature of about 400°C. As a high temperature is applied in the first strengthening step (S100), it is possible to control the potassium ions to penetrate to the deepest penetration depth inside the glass. Thereafter, in the second strengthening step S200, a temperature lower than that of the first strengthening step S100 is applied to control the potassium ions to evenly penetrate the shallow surface of the glass, so that smooth ion exchange may be performed.

If, on the contrary, when a temperature lower than that of the first strengthening step (S100) is applied to the second strengthening step (S200), a sufficient strengthening temperature to allow the large particle potassium ions to penetrate into the glass is not applied, so that the penetration depth There is a problem with falling.

Accordingly, a case of substitution occurs in a shallow layer close to the surface of the glass, and even if a high temperature is applied in the second strengthening step (S200), the potassium ions of the large particles substituted in the surface layer are transferred to the inside of the glass. A phenomenon that prevents movement occurs. That is, it may be difficult to smooth ion exchange or diffusion to deep layers inside the glass tissue. Therefore, it is desirable to design the experiment so that the strengthening is performed step by step from the highest temperature to the lowest temperature.

In the second strengthening step (S200), the glass may be immersed in the composition for manufacturing the second strengthened glass. The composition for manufacturing the second tempered glass and the composition for manufacturing the first tempered glass may each include a first potassium salt and a second potassium salt, as described above. For the composition for producing the first tempered glass and the composition for producing the second tempered glass, the above-described composition for producing the tempered glass may be applied.

The composition for producing the first tempered glass and the composition for producing the second tempered glass may have different compositions. Specifically, the content of the second potassium salt in the composition for producing the first tempered glass and the content of the second potassium salt in the composition for producing the second tempered glass may be different from each other.

In the case of the low specific potassium salt contained in the second potassium salt, the boiling point is formed to be low, and the phase shift occurs more quickly than the high specific potassium salt.

At this time, when the second strengthening step (S200) is performed at a temperature lower than the first strengthening step (S100), a phenomenon in which the thermal energy to be used for ion exchange is first used for the phase transition of the low specific gravity potassium salt occurs. .

Accordingly, there is a problem in that sufficient heat to be used for ion exchange after phase shift is not provided, so that the replacement rate is lowered and ion exchange is not performed smoothly.

Therefore, by lowering the content of the second potassium salt in the immersion solution used in the second strengthening step (S200) compared to the first strengthening step (S100), the thermal energy used for the phase transition of the low specific gravity potassium salt contained in the second potassium salt It is possible to minimize consumption, and thus improve the replacement speed.

According to an embodiment of the present invention, different strengthening conditions are formed by different process conditions of the first strengthening step (S100) and the second strengthening step (S200), and accordingly, ions are exchanged evenly to a relatively deep area. Make it possible.

Due to this, compared to the conventional chemical strengthening method, the occurrence of fine cracks and scratches can be minimized to prevent glass breakage, and there is an effect of further improving impact resistance.

Furthermore, the method for manufacturing a tempered glass according to an embodiment of the present invention may further include the following additional steps.

In an embodiment of the present invention, a preheating step may be performed before the first and second strengthening steps described above.

In the case of preheating glass that has not been preheated in the above-described composition for producing tempered glass and a jig that supports and assists the glass during processing, there is a concern that damage and defects may occur due to the difference in the expansion coefficient of the two materials. There is.

Therefore, by going through a process of preheating the glass prior to the tempering treatment, it is possible to increase the activity of the structure within the glass, as well as to match the degree of thermal expansion with the jig similarly.

The preheating conditions may be appropriately adjusted according to the size and thickness of the glass and the composition ratio or temperature conditions of the composition for producing a tempered glass. However, the preheating temperature should be lower than the tempering temperature, and may be provided in a temperature range of about 70°C to about 400°C.

At this time, if the preheating temperature is less than about 70℃, sufficient preheating may not be achieved, and if it exceeds about 400℃, the reinforcement temperature may be exceeded, so that the temperature is maintained around 350℃. It is desirable.

The preheating time is sufficient as long as heat can be transferred to the inside of the glass, and may be performed for about 20 minutes to about 90 minutes.

Such a preheating step is essential to the method of manufacturing the tempered glass of the present invention, and by performing the preheating step, there is an effect of facilitating the flow of ions inside the glass so that the exchange of ions can occur better.

In addition, in an embodiment, a slow cooling step that is additionally performed after the first strengthening step and before the second strengthening step may be performed.

The slow cooling step is a step of gradually cooling the tempered glass, preventing deformation and breakage of the glass, and removing stress remaining on the glass.

Through the slow cooling step, the compressive strength of the glass surface can be obtained, and at the same time, the density of the internal structure of the glass can be improved, and the surface structure is also maintained uniformly, thereby obtaining a beautiful surface.

The thinner or smaller the glass is, the more necessary multi-stage cooling treatment is required. At this time, in the case of rapid cooling, the strength of the glass may be slightly improved, but there is a risk of damage to the glass, so the method of gradually slow cooling using hot water is most preferable.

During slow cooling, the temperature of hot water may be provided at about 40°C to about 90°C.

In addition, in an embodiment, after the above-described slow cooling step, a washing step for removing foreign substances or chips on the glass surface may be performed.

The cleanliness in each process for manufacturing the tempered glass significantly affects the uniformity of the quality of the tempered glass and lowering the defect rate, and may affect the transmittance of the manufactured glass, so a cleaning process is required.

At this time, since there is a concern that scratches may occur on the glass surface when washing through high-pressure spraying, it is preferable to use a flow washing method using natural pressure.

In addition, in an embodiment, a water and latent heat removal step of removing moisture and latent heat of the tempered glass on which the reinforcement treatment has been completed may be performed.

The glass immediately after the reinforcement treatment is completed, the strength and the latent heat must be removed to fully exhibit the reinforced strength, and thus the prepared tempered glass must be left at room temperature without a separate packaging treatment to remove moisture and latent heat.

The step of removing moisture and latent heat may be performed for about 1 to about 3 days after the slow cooling step.

2 is a cross-sectional view showing a tempered glass manufactured through a method of manufacturing a tempered glass according to an embodiment of the present invention.

Referring to FIG. 2, since the density of the actual tempered glass 10 is gradually increased from the outer edge of the central layer 200 present in the center of the glass toward the surface of the stress layer 100, the central layer 200 and the stress There may not be a clear boundary between the layers 100 in which the density rapidly changes.

Here, the central layer 200 exists in the center of the glass and may represent a layer surrounded by the stress layer 100. Unlike the stress layer 100, the central layer 200 is a layer that is not subjected to ion exchange.

For example, when the glass is immersed in the composition for producing a tempered glass of the present invention, the stress layer 100 is formed as sodium ions inside the glass surface layer are replaced with potassium ions, so that a large number of potassium is distributed.

On the contrary, it is difficult for potassium to penetrate to the central portion of the glass to some extent, so the central layer 200 containing sodium is formed in the central portion of the glass, and is protected by the stress layer 100.

Here, when all of the sodium ions of the central layer 200 are replaced with potassium ions, it is difficult to form the stress layer 100 in the internal structure of the glass, and the strengthening is not performed smoothly.

Therefore, maintaining the sodium content of the central layer 200 within a certain range is the core of the glass strengthening technology.

For this, it is necessary to appropriately control the depth of penetration (DOL) of potassium ions into the glass through the control of the reinforced environmental conditions such as the composition ratio of the immersion solution, the temperature and the immersion time.

According to an embodiment of the present invention, as the method of manufacturing a tempered glass includes a first strengthening step and a second strengthening step performed under different process conditions, it is possible to independently control the ion penetration depth in each step.

In other words, by evenly penetrating potassium ions from the center layer inside the glass to the glass surface layer, it is possible to manufacture a tempered glass of uniform and excellent quality.

Accordingly, it is possible to prevent glass breakage by minimizing the occurrence of fine cracks and scratches compared to the conventional chemical strengthening method, and to further improve impact resistance.

The term "includes" described above means that the corresponding component may be included unless otherwise stated, and thus other components may be further included rather than excluding other components. All terms, including technical or scientific terms, unless otherwise defined, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Terms commonly used, such as terms, should be interpreted as being consistent with the meaning in the context of the related technology, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

10: tempered glass
100: stress layer
200: center floor

Claims (10)

First potassium salt; And
It contains a second potassium salt different from the first potassium salt,
The first potassium salt is a high specific gravity potassium salt having a specific gravity higher than 2.0,
The second potassium salt is a low specific gravity potassium salt having a specific gravity of 1.4 to 2.0,
The second potassium salt is contained 1 to 30 parts by weight based on 100 parts by weight of the total composition, a composition for producing a tempered glass. The method of claim 1,
The low specific gravity potassium salt,
Potassium Formate, Potassium Oxalate, Potassium Acetate, Potassium Methoxide, Potassium Ethoxide, and Potassium Bicarbonate (Potassium bicarbonate) A composition for producing a tempered glass containing at least one or more of potassium salts. The method of claim 1,
The composition for preparing the tempered glass is provided at a temperature of 300°C to 550°C, a composition for producing a tempered glass. A first tempering step of immersing the glass in the composition for producing a first tempered glass in a first temperature range; And
Including a second strengthening step of immersing the glass in the composition for producing a second strengthened glass in a second temperature range different from the first temperature range,
Each of the composition for producing the first tempered glass and the composition for producing the second tempered glass
First potassium salt; And
It contains a second potassium salt different from the first potassium salt,
The first potassium salt is a high specific gravity potassium salt having a specific gravity higher than 2.0,
The second potassium salt is a low specific gravity potassium salt having a specific gravity of 1.4 to 2.0, the tempered glass manufacturing method. The method of claim 4,
The first strengthening step is carried out at a temperature of 450 ℃ to 550 ℃, tempered glass manufacturing method. The method of claim 4,
The second strengthening step is performed at a lower temperature than the first strengthening step. The method of claim 4,
The second strengthening step is performed at a temperature of 300°C to 500°C. The method of claim 4,
The content of the second potassium salt in the composition for producing the first tempered glass and the content of the second potassium salt in the composition for producing the second tempered glass are different from each other, a method for producing a tempered glass. The method of claim 8,
The content of the second potassium salt in the composition for producing the second tempered glass is lower than the content of the second potassium salt in the composition for producing the first tempered glass. The method of claim 4,
The low specific gravity potassium salt,
Potassium Formate, Potassium Oxalate, Potassium Acetate, Potassium Methoxide, Potassium Ethoxide, and Potassium Bicarbonate (Potassium bicarbonate) A method for producing a tempered glass comprising at least one or more of potassium salts.

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