KR101468670B1 - Alkali glass and method for manufacturing the same - Google Patents

Abstract

The present invention discloses an alkali glass which is light and has good processability and is suitable for chemical strengthening treatment, and a method for producing the same. A glass according to one aspect of the present invention is an alkali glass, comprising 55 to 67% of SiO ₂ , expressed as% by weight based on the oxide; Al ₂ O ₃ 10.5 to 15.5%; Na ₂ O 11 to 18%; K ₂ O 0.5 to 8%; 11 to 17% MgO; And 0 to 1% of CaO.

Description

Alkali glass and method of manufacturing same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass manufacturing technique, and more particularly, to an alkali glass composition and a method for manufacturing such a glass.

Among them, flat glass is used in various fields such as window glass, window screen of a vehicle, mirror, and the like, and the kind thereof is also developed and used in various ways to suit the application.

Glass may be required to have a variety of properties depending on the equipment, equipment, and location to which it is applied. Among them, the mechanical strength of glass is one of the characteristics that has recently become important. Since the glass has characteristics that are fragile due to its characteristics, the improvement of the mechanical strength of the glass is a very important factor in improving the usability of the glass.

Furthermore, in recent years, display devices such as mobile phones, portable computers, digital cameras, and PDAs such as smart phones have become widespread, and glass can also be used for such display devices. In particular, a touch panel is often applied to such a display device. Cover glass is commonly used for a display device to which such a touch panel is applied.

The cover glass is also called a protective glass, and high mechanical strength is required for its application characteristics. Therefore, in such a display device, a tempered glass substrate having improved mechanical strength of the glass substrate as the cover glass is mainly used. The tempered glass substrate can be manufactured in various ways, but the most commonly used method is to chemically strengthen the glass substrate. Such a chemical strengthening mode is generally performed by chemically treating the glass substrate, for example, by immersing the glass substrate in a solution such as potassium nitrate to cause ion exchange in the glass substrate.

As described above, in order to manufacture the chemically tempered glass, the glass substrate is chemically treated, and the mechanical strength of the glass substrate is improved through ion exchange. Thus, in order to produce chemically tempered glass, there is a need for a glass that is suitable for chemical reinforcement treatment, such as a suitable composition to ensure good ion exchange performance.

In addition to being suitable for chemical reinforcement, glass also needs to be equipped with a variety of other properties.

For example, in the case of a glass used for a display device such as a smart phone, a PDA, or a TV, lightness must be secured. Particularly, in recent years, as the display device such as a TV or a monitor is gradually enlarged, the area of the glass used for the display device is also becoming larger. In this case, since the warping of the glass due to the load of the glass itself may become larger, the glass needs to be made lighter in order to prevent it. In addition, when such a glass is used in a small portable display device such as a cellular phone, a PDP, and a notebook, it is required to reduce the weight of glass in order to improve portability.

In addition, the glass should have adequate processability. Otherwise, it is difficult to process the glass, so that it is difficult to produce a glass product meeting the desired shape and quality, and the energy and time required for the processing are increased and the productivity of the glass product may be decreased.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an alkali glass which is light and has good processability and is suitable for chemical strengthening treatment, and a method for producing the alkali glass.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

In order to achieve the above object, the present inventor has invented a glass composition suitable for chemical strengthening while having desirable physical properties after repeated studies on alkali glass.

A glass according to one aspect of the present invention is an alkali glass, comprising 55 to 67% of SiO ₂ , expressed as% by weight based on the oxide; Al ₂ O ₃ 10.5 to 15.5%; Na ₂ O 11 to 18%; K ₂ O 0.5 to 8%; 11 to 17% MgO; And 0 to 1% of CaO.

Preferably, the alkali glass contains SiO _{2 in an amount of} 57 to 65% by weight based on the oxide; Al ₂ O ₃ 10.5 to 14%; Na ₂ O 11 to 15%; K ₂ O 0.5 to 6%; And 11 to 15% of MgO.

Also preferably, the alkali glass has a density of 2.55 g / cm ³ or less.

Preferably, the alkali glass has a coefficient of thermal expansion of 7.0 占^10-6 / 占 폚 to 9.0 占^10-6 / 占 폚.

Preferably, the alkali glass has a temperature of 1200 ° C or less at a viscosity of 10 ⁴ dPas.

Preferably, the alkali glass has a distortion point of 570 캜 or higher.

According to another aspect of the present invention, there is provided a tempered glass which is chemically reinforced with the above-described alkali glass.

Preferably, the tempered glass has a surface compressive stress of greater than 400 MPa.

Also preferably, the tempered glass has a thickness of the compressive stress layer of more than 10 mu m.

More preferably, the tempered glass has a surface compressive stress exceeding 600 MPa.

Also preferably, the tempered glass has a thickness of the compressive stress layer of more than 20 mu m.

According to another aspect of the present invention, there is provided a display device comprising the above-described alkali glass.

According to another aspect of the present invention, there is provided a method of manufacturing an alkali glass, the method comprising the steps of: 55 to 67% of SiO ₂ ; Al ₂ O ₃ 10.5 to 15.5%; Na ₂ O 11 to 18%; K ₂ O 0.5 to 8%; 11 to 17% MgO; And 0 to 1% of CaO.

Preferably, the glass raw material combining step comprises 57 to 65% of SiO ₂ , expressed as oxide based weight%; Al ₂ O ₃ 10.5 to 14%; Na ₂ O 11 to 15%; K ₂ O 0.5 to 6%; And 11 to 15% of MgO.

Also preferably, the density of the produced glass is 2.55 g / cm ³ or less.

Further, preferably, the produced glass has a thermal expansion coefficient of 7.0 × 10 ^-6 / ° C. to 9.0 × 10 ^-6 / ° C.

Also preferably, the viscosity of the produced glass is at a temperature of 10 < ⁴ > dPas below 1200 < 0 > C.

Also preferably, the distortion point of the produced glass is 570 캜 or higher.

According to another aspect of the present invention, there is provided a method of manufacturing a tempered glass, the method including chemically reinforcing the glass produced by the alkali glass manufacturing method.

Preferably, the surface tempering stress of the prepared tempered glass is greater than 400 MPa.

Also preferably, the produced tempered glass has a compressive stress layer thickness of more than 10 mu m.

More preferably, the surface tempering stress of the prepared tempered glass exceeds 600 MPa.

Also preferably, the compressive stress layer thickness of the prepared tempered glass is greater than 20 [mu] m.

According to the present invention, an alkali glass suitable for improving the strength in a chemical strengthening manner can be provided. In particular, according to one aspect of the present invention, there is provided an alkali aluminosilicate glass suitable for chemical strengthening.

Further, according to the present invention, when tempered glass is produced by chemical strengthening treatment, it is possible to increase the surface compressive stress while increasing the thickness of the compressive stress layer.

Therefore, the glass according to the present invention can be usefully used for a cover glass of a display device which requires high mechanical strength.

According to another aspect of the present invention, a glass having a low density can be provided. Therefore, even if the glass plate has a large area, it is possible to reduce the warping due to its own weight, and it can meet the trend of increasing the size of display devices such as TVs and monitors. In addition, even in the case of a small portable device such as a portable telephone or a notebook in which a glass plate is used, its weight can be reduced, and portability can be improved.

According to still another aspect of the present invention, a glass having a coefficient of thermal expansion of 7.0 × 10 ^-6 / ° C. to 9.0 × 10 ^-6 / ° C. can be provided. Therefore, it is suitable for use with a material having a thermal expansion coefficient in a similar range.

Further, according to another aspect of the present invention, the temperature T ₄ at a temperature of 10 ⁴ dPas is low, so that the processing temperature of the glass can be lowered and the processing of the glass can be facilitated. Therefore, it is possible to reduce the energy and time required for processing the glass, so that the productivity of the glass and the product using the same can be improved.

In addition, according to another aspect of the present invention, a glass having a high distortion point can be provided. Thus, since the chemical strengthening treatment can be performed at a high temperature, the chemical strengthening treatment time of the glass can be shortened. In addition, since deformation does not easily occur at a high temperature, various high-temperature treatments can be performed in a post-treatment process after the chemical strengthening process of the glass, so that the glass can be used in a wider range.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart schematically illustrating a process for producing aluminosilicate glass according to one embodiment of the present invention.
FIG. 2 is a graph comparing the compressive stress and the compressive stress layer thickness measurement results formed in the chemical strengthening treatment for the glass of one embodiment and the comparative example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, it should be understood that the embodiments described herein are merely the most preferred embodiments of the present invention, and are not intended to be exhaustive of the present invention, so that various equivalents and modifications It should be understood.

The glass according to the present invention is an alkali aluminosilicate glass containing, in particular, an alkali metal oxide, aluminum oxide and silicon dioxide.

More specifically, the alkali glass according to the present invention may contain SiO ₂ , Al ₂ O ₃ , Na ₂ O, K ₂ O, MgO and CaO as constituent components.

In particular, the alkali glass according to the present invention may contain 55 to 67% by weight of SiO ₂ based on oxide. SiO ₂ is a network structure product oxide that forms glass, which can contribute to increase the chemical resistance of the glass and to have an appropriate coefficient of thermal expansion that can be matched with the surrounding material of the glass. However, if SiO ₂ is contained too high, melting and molding of the glass becomes difficult, the coefficient of thermal expansion becomes too low, and the devitrification properties of the glass may deteriorate. On the other hand, when SiO ₂ is contained too low, the chemical resistance is reduced, the density is increased, the thermal expansion coefficient is increased, and the strain point may be lowered. Accordingly, the alkali-free glass according to the present invention include SiO ₂ being 55 ~ 67% by weight. Preferably, the SiO ₂ is contained in an amount of 57 to 65% by weight. More preferably, the SiO ₂ is contained in an amount of 58 to 63% by weight.

The alkali glass according to the present invention may contain 10.5 to 15.5% by weight of Al ₂ O ₃ based on the oxide. Al ₂ O ₃ increases the high temperature viscosity, chemical stability and thermal shock resistance of glass, and can contribute to enhancement of strain point and Young's modulus. However, when Al ₂ O ₃ is contained too high, the devitrification resistance, hydrochloric acid resistance and BHF resistance can be decreased and the viscosity can be increased. On the other hand, when the content of Al ₂ O ₃ is too low, the effect of the addition is hardly achieved and the modulus of elasticity can be lowered. Therefore, the alkali glass according to the present invention contains 10.5 to 15.5% by weight of Al ₂ O ₃ . Preferably, the Al ₂ O _{3 content} is 10.5 to 14% by weight. More preferably, the Al ₂ O ₃ is contained in an amount of 11 to 13% by weight.

The alkali glass according to the present invention may contain 11 to 18% by weight of Na ₂ O based on oxide. Na ₂ O is a component to be ion-exchanged in the chemical strengthening treatment process in a potassium nitrate (KNO ₃ ) solution or the like, and can improve the melting property, moldability or moldability of the glass, lower the viscosity of the glass at high temperature, have. However, when Na ₂ O is contained excessively, the coefficient of thermal expansion of the glass becomes too large to be matched with the surrounding material, and the resistance to devitrification and thermal shock may be deteriorated. On the other hand, if Na ₂ O is contained too low, the effect of the addition is difficult to achieve and the ion exchange performance in the chemical strengthening treatment process may be deteriorated. Accordingly, the alkali-free glass according to the present invention include 11 ~ 18 wt% of Na ₂ O. Preferably, the Na ₂ O content is contained in an amount of 11 to 15% by weight. More preferably, the Na ₂ O is contained in an amount of 11 to 13% by weight.

The alkali glass according to the present invention may contain 0.5 to 8% by weight of K ₂ O based on oxide. K ₂ O accelerates ion exchange in the glass chemical strengthening process and lowers the high temperature viscosity of the glass to improve the melting property and moldability and can contribute to the reduction of the crack incidence. However, if K ₂ O is contained too high, the coefficient of thermal expansion of the glass becomes too large to be easily matched with the surrounding material, thermal shock resistance may deteriorate, and resistance to devitrification may be deteriorated. On the other hand, if K ₂ O is contained too low, the effect of the addition is difficult to achieve and the ion exchange performance in the chemical strengthening treatment process may be deteriorated. Therefore, the alkali glass according to the present invention contains 0.5 to 8% by weight of K ₂ O. Preferably, K ₂ O is contained in an amount of 0.5 to 6 wt%. More preferably, K ₂ O is contained in an amount of 0.5 to 3% by weight.

In addition, the alkali glass according to the present invention may contain 11 to 17% by weight of MgO based on oxide. MgO is an alkaline earth metal oxide which does not excessively increase the coefficient of thermal expansion and can contribute to improving the melting property without significantly lowering the strain point. In particular, MgO can reduce the density of glass, and can contribute to weight reduction of glass. However, when the content of MgO is too high, the devitrification property of the glass may be deteriorated and the acid resistance and the BHF resistance may be deteriorated. On the other hand, when the content of MgO is too low, it is difficult to achieve the MgO addition characteristics described above. Therefore, the alkali glass according to the present invention contains more than 11 wt% and less than 17 wt% MgO. Preferably, the MgO is contained in an amount of more than 11 wt% to 15 wt% or less. More preferably, the MgO content is more than 11 wt% and not more than 13 wt%.

Further, the alkali glass according to the present invention may contain 0 to 1% of CaO in terms of oxide based on weight%. CaO, like MgO, is an alkaline earth metal oxide that can contribute to lowering the density and the thermal expansion coefficient, and not significantly lowering the strain point, and improving the meltability. However, when CaO is contained too high, the density and the thermal expansion coefficient may become large and the chemical resistance such as the internal BHF performance may be deteriorated. Thus, the alkali glass according to the invention comprises less than 1% by weight of CaO.

Preferably, the alkali glass according to the present invention may have a density of 2.55 g / cm ³ or less. According to this embodiment, the density of the glass is low, so that it is easy to achieve weight reduction of the glass product. Particularly, in a situation where a glass device is enlarged as a display device and the area of the glass is gradually increasing, when the density of the glass is lowered, the warping due to the self-load of the glass is reduced and the weight of the glass- . Further, the weight of the glass itself can be lowered also for a portable apparatus or a device, and portability can be improved.

Also, preferably, the alkali glass according to the present invention may have a coefficient of thermal expansion (CTE) of 7.0 × 10 ^-6 / ° C. to 9.0 × 10 ^-6 / ° C. According to this aspect, it is possible to prevent the problem of peeling due to the thermal expansion difference when the material is used together with a material having a similar range of thermal expansion coefficient, such as a similar range of metal, organic adhesive, and the like.

Also preferably, the alkali glass according to the present invention may have a T ₄ of 1200 ° C or less at a temperature of 10 ⁴ dPas. According to this embodiment, since the T ₄ associated with the processing temperature of the glass is low, the processing of the glass can be facilitated, and the energy and time required for processing the glass can be saved.

Also preferably, the alkali glass according to the present invention may have a strain point of 570 캜 or higher. Therefore, according to this aspect of the present invention, the chemical strengthening treatment is possible at a high temperature because the distortion point of the glass is high. Therefore, the time required for the chemical strengthening treatment of the glass can be shortened. In addition, even if the glass substrate is exposed to a high temperature in a process subsequent to the chemical strengthening treatment, deformation does not easily occur, so that the glass substrate can be processed even in a high temperature range, and its application range can be expanded.

The tempered glass according to the present invention can be produced using the above-described alkali glass. That is, the tempered glass according to the present invention comprises 55 to 67% of SiO ₂ , 10.5 to 15.5% of Al ₂ O ₃ , 11 to 18% of Na ₂ O, 0.5 to 8% of K ₂ O, 11 to 17% and CaO of 0 to 1%.

The tempered glass according to the present invention can have a compressive stress layer on its surface by chemical strengthening treatment. At this time, the compressive stress (CS) of the compressive stress layer may exceed 400 MPa. That is, the alkali glass according to the present invention may have a surface compressive stress exceeding 400 MPa during chemical strengthening treatment. More preferably, the compressive stress of the surface compressive stress layer may exceed 600 MPa. More preferably, the surface compressive stress may exceed 900 MPa. According to this embodiment, since the compressive stress of the compressive stress layer is large, the mechanical strength of the tempered glass can be improved.

Further, the tempered glass according to the present invention may have a thickness (DOL) of the compressive stress layer exceeding 10 mu m. That is, the alkali glass according to the present invention may have a thickness of the compressive stress layer formed by chemical strengthening treatment exceeding 10 mu m. More preferably, the thickness of the compressive stress layer may exceed 20 m. More preferably, the thickness of the compressive stress layer may exceed 30 m. According to this embodiment, since the thickness of the compressive stress layer is large, the mechanical strength of the tempered glass can be improved. Particularly, if the thickness of the compressive stress layer is large, the glass may not be damaged even if it is damaged to a certain depth.

The display device according to the present invention may include the above-described alkali glass. In particular, the display device according to the present invention may include a tempered glass in which the above-described alkali glass is chemically reinforced. For example, the display device according to the present invention may be a display device such as an LCD, a PDP, an LED, and an OLED, and the above-described tempered glass may be included as a cover glass (protective glass).

Hereinafter, a method for producing the above-described alkali glass according to a preferred embodiment of the present invention will be described.

1 is a flow chart schematically showing a method for producing an alkali glass according to an embodiment of the present invention.

Referring to FIG. 1, raw materials of respective components contained in glass are first combined to a target composition (S110). At this time, in step S110, the SiO _{2 content} is 55 to 67%, the Al ₂ O _{3 content} is 10.5 to 15.5%, the Na ₂ O content is 11 to 18%, the K ₂ O content is 0.5 to 8% The raw material components are combined so that the MgO content is 11 to 17% and the CaO content is 0 to 1%.

Preferably, the step of S110 is a method of manufacturing a semiconductor device, which comprises 57 to 65% of SiO ₂ , 10 to 14% of Al ₂ O ₃ , 11 to 15% of Na ₂ O, 0.5 to 6 of K ₂ O, %, And MgO in the range of 11 to 15%.

Next, the glass raw material thus combined is heated to a predetermined temperature, for example, 1500 to 1600 ° C to melt the glass raw material (S120), and the melted glass is formed (S130). In this case, step S130 may be performed by a float method using a float bath, but the present invention is not necessarily limited to such a molding method. For example, the step of S130, that is, the step of forming the glass, may be performed by a down draw method or a fusion method.

If the glass is formed in step S130, the formed glass is transferred to the annealing furnace and is slowly cooled (S140). Then, the slowly cooled glass is cut to a desired size, and further processing such as polishing is performed, and the glass product can be manufactured through this series of processes.

As described above, the alkali glass produced by the glass manufacturing method according to an embodiment of the present invention may have a density of 2.55 g / cm < ³ > or less. The thermal expansion coefficient of the produced alkali glass may be 7.0 to 9.0 [占 10 ^-6 / 占 폚]. The alkali glass thus produced may have a T ₄ of 1200 ° C or less and a distortion point of 570 ° C or more.

The method for manufacturing a tempered glass according to the present invention includes chemical strengthening treatment of the glass produced by the above-described alkali glass manufacturing method.

That is, the tempered glass manufacturing method according to the present invention can perform the chemical strengthening treatment of the alkali glass manufactured through steps S110 to S140, after step S140. In this case, the chemical strengthening treatment step may be performed by immersing the alkali glass in a molten salt such as potassium nitrate (KNO ₃ ) for a predetermined time, but the present invention is not necessarily limited to the chemical strengthening treatment method.

Thus, tempered glass produced by the tempered glass manufacturing method according to an embodiment of the present invention may have a surface compressive stress exceeding 400 MPa and a compressive stress layer thickness exceeding 10 탆. Preferably, tempered glass produced in accordance with the present invention can have a surface compressive stress exceeding 600 MPa and a compressive stress layer thickness exceeding 20 탆. More preferably, tempered glass produced according to the present invention may have a surface compressive stress greater than 900 MPa and a compressive stress layer thickness greater than 30 microns.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. It should be understood, however, that the embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Table 1 shows the glass composition and physical properties of the examples according to the present invention.

The raw materials of the respective components were combined so as to have a composition (based on weight%) as shown in Table 1 and melted by heating at 1600 캜 for 3 hours using a platinum crucible. During the melting, a platinum stirrer was inserted and the glass was homogenized by stirring for 1 hour. Subsequently, the molten glass was slowly cooled at 730 DEG C to obtain a glass of each of the Examples. On the other hand, the obtained glass was confirmed by fluorescent X-ray analysis.

Further, density, thermal expansion coefficient, T ₄ , distortion point and standing point were measured by the following methods as physical properties for each glass of the examples, and the results are shown in Table 1.

(density)

For each example glass, the density was measured using the Archimedes method. At this time, the density unit is g / cm ³ .

(Thermal Expansion Coefficient) (CTE)

For each example glass, the average thermal expansion coefficient was measured using a dilatometer. At this time, the thermal expansion coefficient unit is 10 ^-6 / ° C.

(T ₄ )

For each example glass, the viscosity was measured using a high-temperature viscometer, and the temperature T ₄ at which the viscosity reached 10 ⁴ dPa · s was measured. In this case, the unit of T ₄ is ° C.

(Distortion point)

For each example glass, the distortion points were measured by the fiber elongation method using ASTM C336. In this case, the unit of the distortion point is ° C.

(West cold point)

For each example glass, the cold point was measured by a fiber elongation method using ASTM C336. At this time, the unit of the standing cold point is ℃.

Referring to Table 1, the glass of Examples (Examples 1 to 10) had a density of 2.55 g / cm ³ or less and an average coefficient of thermal expansion (CTE) of 7.0 to 9.0 (x 10 ^-6 / .

Further, in the case of the glass of the examples, it was confirmed that T ₄ was 1200 ° C or less, and more preferably 1130 ° C or less. In the case of the glass of the examples, it was confirmed that the strain point was as high as 570 캜 or more.

As a result of various physical property measurement results of this embodiment, it can be seen that the alkali glass according to the present invention is low in density and easy to achieve weight reduction. In addition, in the case of the alkali glass according to the present invention, it can be seen that T ₄ is low and the workability of the glass is good. In the case of the alkali glass according to the present invention, it can be seen that the chemical strengthening is possible at a high temperature since the distortion point is high.

In addition, the alkali glass according to the present invention can be formed to have a high surface compressive stress and a high compressive stress layer in the chemical strengthening treatment.

In order to examine these effects, the surface compressive stress (CS) and the compressive stress layer thickness (DOL) were measured after the chemical strengthening treatment was performed on the glass of Example 1. The results are shown in Table 2.

At this time, the compressive stress and the compressive stress layer thickness were measured using a surface stress measuring instrument (FSM-6000LE).

Here, the chemical strengthening treatment was performed by immersing the glass of Example 1 for a predetermined time in a bath containing a potassium nitrate (KNO ₃ ) solution. At this time, the chemical strengthening treatment temperature and time for Example 1 are as shown in Table 2.

For comparison with the chemical strengthening treatment effect of Example 1, a glass of a predetermined comparative example was prepared.

At this time, the glass of the comparative example was prepared such that each of the raw materials was changed to 70.6% of SiO ₂ , 1.9% of Al ₂ O ₃ , 13.3% of Na ₂ O, 0.3% of K ₂ O, 4.6% of MgO and 8.8% And then melted by heating at a temperature of 1600 ° C for 3 hours using a platinum crucible as in the above example, followed by slow cooling at 730 ° C.

The surface compression stress (CS) and the compressive stress layer thickness (DOL) were measured after the chemical strengthening treatment was applied to the thus obtained comparative glass. The results are shown in Table 3.

Also in this comparative example, the chemical strengthening treatment was performed by immersing the glass of the comparative example in a bath containing a potassium nitrate (KNO ₃ ) solution for a predetermined time. At this time, the temperature and time for the chemical strengthening treatment for the glass of the comparative example are as shown in Table 3.

On the other hand, the measurement results of the compressive stress and the compressive stress layer thickness for the glass of Example 1 of Table 2 and Table 3 and the glass of the comparative example are shown in Fig. 2 for convenience of comparison.

Referring to Tables 2 and 3 and FIG. 2, in the case of the glass of Example 1 according to the present invention, the compressive stress layer is formed to have a sufficient thickness from 10 탆 to 30 탆, It can be seen that the stress is formed to be very high, more than 930 MPa and more than 1000 MPa. On the other hand, in the case of the glass of the comparative example, the compressive stress layers are all 15 μm or less and the compression stress is relatively low, ie, 750 MPa or less.

Therefore, even when the chemical tempered glass is manufactured using the alkali glass according to the present invention, it is possible to increase the compressive stress while securing the thickness of the compressive stress layer to a certain level or more. Can be confirmed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

Claims (17)

As an oxide based weight percent indication,
55 to 67% SiO ₂ ;
Al ₂ O ₃ 10.5 to 15.5%;
Na ₂ O 11 to 18%;
K ₂ O 0.5 to 8%;
11 to 17% MgO; And
CaO 0 to 1%
And the distortion point is 570 DEG C or higher. The method according to claim 1,
As an oxide based weight percent indication,
57 to 65% SiO ₂ ;
Al ₂ O ₃ 10.5 to 14%;
Na ₂ O 11 to 15%;
K ₂ O 0.5 to 6%; And
MgO 11 to 15%
≪ / RTI > The method according to claim 1,
An alkali glass having a density of 2.55 g / cm ³ or less and a coefficient of thermal expansion of 7.0 x 10 ^-6 / ° C to 9.0 x 10 ^-6 / ° C. The method according to claim 1,
Wherein the temperature at a viscosity of 10 < ⁴ > dPas is 1200 DEG C or less. delete A tempered glass chemically reinforced with an alkali glass according to any one of claims 1 to 4. The method according to claim 6,
Wherein the surface compressive stress exceeds 400 MPa and the compressive stress layer thickness exceeds 10 mu m. The method according to claim 6,
Wherein the surface compressive stress exceeds 600 MPa and the compressive stress layer thickness exceeds 20 mu m. A display device comprising an alkali glass according to any one of claims 1 to 4. As an oxide based weight percent indication,
55 to 67% SiO ₂ ;
Al ₂ O ₃ 10.5 to 15.5%;
Na ₂ O 11 to 18%;
K ₂ O 0.5 to 8%;
11 to 17% MgO; And
CaO 0 to 1%
, So that the strain point of the produced glass is at least 570 캜. 11. The method of claim 10,
Wherein the glass raw material combining step comprises:
As an oxide based weight percent indication,
57 to 65% SiO ₂ ;
Al ₂ O ₃ 10.5 to 14%;
Na ₂ O 11 to 15%;
K ₂ O 0.5 to 6%; And
MgO 11 to 15%
By weight based on the total weight of the alkali glass. 11. The method of claim 10,
Wherein the density of the produced glass is 2.55 g / cm ³ or less, and the coefficient of thermal expansion of the produced glass is 7.0 × 10 ^-6 / ° C to 9.0 × 10 ^-6 / ° C. 11. The method of claim 10,
Wherein the glass has a viscosity of 10 < ⁴ > dPas and a temperature of 1200 DEG C or less. delete 14. A method for manufacturing tempered glass comprising the step of chemically reinforcing a glass produced by the method for producing an alkali glass according to any one of claims 10 to 13. 16. The method of claim 15,
The tempered glass produced has a surface compressive stress exceeding 400 MPa and a compressive stress layer thickness exceeding 10 탆. 16. The method of claim 15,
Wherein the tempered glass produced has a surface compressive stress exceeding 600 MPa and a compressive stress layer thickness exceeding 20 mu m.

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