WO2013032292A2 - Alkali-free glass and method for manufacturing same - Google Patents

Abstract

Disclosed are a structure for alkali-free glass which does not comprise alkali metal oxides, and a method for manufacturing such glass. The alkali-free glass according to the present invention contains 68-75% SiO₂, 1-3% B₂O₃, 4-13% Al₂O₃, 1-6% MgO, 1-11% CaO, 4-9% SrO, and 3-7% BaO, in terms of weight % of oxides, and does not substantially contain alkali metal oxides.

Description

Alkali-free glass and its manufacturing method

This application is a priority application for Korean Patent Application No. 10-2011-0089155, filed September 2, 2011, and Korean Patent Application No. 10-2012-0096355, filed August 31, 2012. All the contents disclosed in the specification and drawings of this application are incorporated in this application by reference.

TECHNICAL FIELD This invention relates to the glass manufacturing technique. More specifically, it is related with the alkali free glass composition which does not contain the alkali metal oxide, and the manufacturing method of such glass.

Glass, especially flat glass, is used in various fields such as window glass, window screens of vehicles, mirrors, and the like, and its type is also being developed and used in various ways.

In particular, alkali-free glass substrates are widely used in flat panel display devices such as LCDs, PDPs, and organic ELs. In the case of the alkali glass substrate containing an alkali metal oxide component, since alkali metal ions in a glass substrate can diffuse in a thin film and deteriorate a film | membrane characteristic, alkali free glass is widely used for display rather than alkali glass.

By the way, in the case of such a glass for flat panel display substrates, various product characteristics are calculated | required.

For example, in the case of glass for flat panel displays, weight reduction should be ensured. In particular, in recent years, as display devices such as TVs and monitors are gradually enlarged, the area of the substrate glass used therein is also increasing. In this case, since the warping phenomenon of the substrate glass due to the load of the substrate glass itself can be further increased, in order to prevent this, the substrate glass needs to be manufactured to have a lighter weight. In addition, the substrate glass may be used in a small portable display device such as a mobile phone, a PDP, a notebook computer, and even in this case, it is required to reduce the weight of the substrate glass.

In addition, in the case of the glass for a flat panel display substrate, heat resistance must be appropriately ensured. For example, in the manufacturing process of a flat panel display device such as a TFT-LCD, various heat treatment processes may be performed. In this process, the glass substrate may be exposed to rapid heating and quenching environments. In this situation, when the heat resistance is not secured to the glass, deformation or warping of the glass may occur, and the glass substrate may be broken due to the tensile stress caused by the heat. Moreover, in the case of the glass for TFT-LCD, when the heat resistance is low, a difference in thermal expansion may occur between the TFT material and the pixel pitch of the TFT may be shifted, which may cause display defects.

In addition, glass for flat panel display substrates must have a sufficiently high transition temperature with respect to heat treatment and molding stability, and have a sufficiently high modulus of elasticity and high modulus of elasticity for mechanical stability and specific gravity of the glass substrate upon conversion to a larger display format. There is also a need for a property that must have.

Accordingly, an object of the present invention is to provide a non-alkali glass and a method for producing the same, which are invented to solve the above problems and which are light and have adequate heat resistance and mechanical stability.

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. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

Glass according to the present invention for achieving the above object, as an alkali-free glass, in terms of the oxide-based weight percent display, SiO ₂ 68 ~ 75%; B ₂ O ₃ 1-3%; Al ₂ O ₃ 4-13%; MgO 1-6%; CaO 1-11%; SrO 4-9%; And BaO 3-7% and are substantially free of alkali metal oxides.

Preferably, the alkali free glass has a density of less than 2.5 g / cm ³ and a thermal expansion coefficient of 3.0 × 10 ⁻⁶ / K to 4.0 × 10 ⁻⁶ / K.

Also preferably, the alkali free glass has a transition temperature of greater than 670 ° C., an elastic modulus of more than 77 GPa, and an intrinsic elastic modulus of more than 31 GPa · cm ³ / g.

In addition, the display device according to the present invention for achieving the above object includes the above-described glass.

Preferably, the display device is a liquid crystal display device.

In addition, the glass manufacturing method according to the present invention for achieving the above object, as an alkali-free glass manufacturing method, in terms of the oxide-based weight% display, SiO ₂ 68 ~ 75%; B ₂ O ₃ 1-3%; Al ₂ O ₃ 4-13%; MgO 1-6%; CaO 1-11%; SrO 4-9%; And combining the glass raw materials to contain BaO 3-7% and substantially no alkali metal oxides.

Preferably, the alkali free glass manufactured by the said glass manufacturing method has a density less than 2.5 g / cm <^3> , and a thermal expansion coefficient is 3.0 * 10 <^-6> / K-4.0 * 10 <^-6> / K.

Also preferably, the alkali free glass produced by the glass production method has a transition temperature of more than 670 ° C, an elastic modulus of more than 77 GPa, and an intrinsic elastic modulus of more than 31 GPa · cm ³ / g.

According to this invention, the alkali free glass which does not contain the alkali metal oxide component substantially is provided.

In particular, according to one embodiment of the present invention, a low density alkali free glass may be provided. Therefore, even in a glass substrate having a large area, it is possible to reduce the warping phenomenon due to its own weight, thereby meeting 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 mobile phone or a notebook using a glass substrate, the weight can be reduced, so that portability can be improved.

In addition, according to one embodiment of the present invention, an alkali free glass having a low coefficient of thermal expansion may be provided. Therefore, even if the glass is exposed to various heat treatment environments during the manufacturing process of the flat panel display device such as the TFT-LCD, it is possible to prevent the phenomenon such as heat shrinkage, deformation, warpage, and cracking. In addition, the thermal expansion coefficient of the alkali free glass is similar to the thermal expansion coefficient of the TFT material, thereby effectively preventing display defects and the like caused by the pixel pitch shifting.

Therefore, in the case of the alkali free glass which concerns on this invention, it is more preferable to be used for flat panel displays, such as a liquid crystal display (LCD), a PDP, and an organic electroluminescent display.

In addition, according to one embodiment of the present invention, an alkali free glass having a high transition temperature (T _g ) may be provided. Therefore, it may have an advantageous effect on heat treatment and molding stability.

In addition, the alkali free glass according to the embodiment of the present invention may have a high modulus of elasticity and a high modulus of elasticity. Thus, it may have sufficient mechanical stability, which may be more advantageous when converting to a larger display format.

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, serve to further understand the technical spirit of the present invention. It should not be construed as limited to.

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

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described herein are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, and various equivalents and modifications that may substitute them at the time of the present application may be used. It should be understood that there may be.

The glass which concerns on this invention is an alkali free glass which does not contain an alkali metal oxide substantially. Here, substantially free of the alkali metal oxide, even if the alkali metal oxide is not contained at all, or even partially contained in the glass, the content is extremely small compared to the other components and the amount that can be neglected as a composition component of the glass If included, it means. For example, when an alkali metal oxide such as Li ₂ O, Na ₂ O and K ₂ O is contained in an amount of 0.2 wt% or less as the glass composition component, it can be said that the alkali metal oxide is not substantially contained.

The alkali-free glass according to the present invention include _{SiO 2, B 2 O 3,} Al 2 O 3, MgO, CaO, SrO and BaO components in the composition.

In particular, alkali-free glass according to the invention may contain 68-75% of SiO ₂ as an oxide based on weight percentages. SiO ₂ is a network structure oxide that forms glass and may contribute to increasing the chemical resistance of the glass and to having an adequate coefficient of thermal expansion. However, when SiO ₂ is contained too high, the coefficient of thermal expansion may be too low and the devitrification characteristics of the glass may be deteriorated. On the other hand, when SiO ₂ is contained too low, the chemical resistance may decrease, the density may increase, the coefficient of thermal expansion may increase, and the strain point may decrease. Accordingly, the alkali-free glass according to the present invention include SiO ₂ being 68 ~ 75% by weight. Preferably, the SiO ₂ is preferably contained 71 to 75% by weight. More preferably, the SiO ₂ is preferably contained 73 to 75% by weight.

Further, the alkali-free glass according to the present invention, may contain 1-3% of B ₂ O ₃ as oxides based on weight percentages. B ₂ O ₃ is a network structure oxide of glass, which can contribute to improving the dissolution reactivity of the glass, reducing the coefficient of thermal expansion, improving the devitrification, improving chemical resistance such as BHF resistance, and lowering the density. However, when B ₂ O ₃ is contained too high, the acid resistance of the glass may be lowered, the density may be increased, and the strain point may be lowered, thereby deteriorating heat resistance. On the other hand, when B ₂ O ₃ is contained too low, the effect of addition is difficult to achieve properly. Accordingly, the alkali-free glass, comprising from 1 to 3% by weight of B ₂ O ₃ in accordance with the present invention. Preferably, the B ₂ O ₃ is preferably contained 1.5 to 2.5% by weight.

Further, the alkali-free glass according to the invention may contain 4-13% of Al ₂ O ₃ as oxides based on weight percentages. Al ₂ O ₃ increases the high temperature viscosity, chemical stability, thermal shock resistance and the like of the glass and may contribute to increase the strain point and Young's modulus. However, when Al ₂ O ₃ is contained too high, it is possible to reduce the devitrification characteristics, hydrochloric acid resistance and BHF resistance and increase the viscosity. On the other hand, when Al ₂ O ₃ is contained too low, its addition effect is difficult to achieve properly and the elastic modulus may be low. Accordingly, the alkali-free glass, comprising 4 to 13% by weight of Al ₂ O ₃ in accordance with the present invention. Preferably, Al ₂ O ₃ is preferably contained 5 to 13% by weight. More preferably, the Al ₂ O ₃ is preferably contained 8 to 12% by weight.

Here, the alkali-free glass according to the present invention, it is preferable to contain an SiO ₂ + Al ₂ O ₃ the total content of SiO ₂ and Al ₂ O ₃ 79 ~ 86% by weight. This is because the effect of containing SiO ₂ and Al ₂ O ₃ can be further improved in such a concentration range, and deterioration of the thermal expansion coefficient and devitrification characteristics can be prevented.

In addition, the alkali free glass which concerns on this invention can contain 1 to 6% of MgO by the oxide basis weight% display. MgO is an alkaline earth metal oxide and does not increase the coefficient of thermal expansion and can contribute to improving meltability without significantly lowering the strain point. In particular, MgO can reduce the density of the glass, which can greatly contribute to the weight reduction of the glass. However, when MgO is contained too high, the devitrification characteristic of glass may fall, and acid resistance and BHF resistance may fall. On the other hand, when MgO is contained too low, it is difficult to achieve the above-mentioned MgO addition characteristic. Therefore, the alkali free glass according to the present invention contains 1 to 6% by weight of MgO. Preferably, the MgO is preferably contained 1 to 5% by weight. More preferably, the MgO is contained 1 to 3% by weight.

In addition, the alkali free glass which concerns on this invention can contain CaO 1 to 11% by an oxide basis weight% display. CaO, like MgO, is an alkaline earth metal oxide that can contribute to lowering the density and coefficient of thermal expansion, not significantly reducing the strain point, and improving meltability. However, when CaO is contained too high, the density and the coefficient of thermal expansion can be large and the chemical resistance such as BHF resistance can be degraded. On the other hand, when CaO is contained too low, the characteristic improvement effect by addition of CaO mentioned above is hard to achieve correctly. Therefore, the alkali free glass according to the present invention contains 1 to 11 wt% of CaO. Preferably, the CaO is preferably contained 1 to 8% by weight. More preferably, the CaO is contained 2 to 6% by weight.

In addition, the alkali free glass which concerns on this invention can contain 4 to 9% of SrO by the oxide basis weight% display. SrO is an alkaline earth metal oxide and can contribute to improvement of the devitrification property and acid resistance of glass. However, when SrO is contained too high, the coefficient of thermal expansion or density may increase, and devitrification characteristics may deteriorate. On the other hand, when SrO is contained too low, the effect of adding SrO as described above is difficult to be properly achieved. Thus, the alkali free glass according to the present invention comprises 4-9% by weight of SrO. Preferably, the SrO is preferably contained 4 to 6.5% by weight. More preferably, the SrO is preferably contained 4 to 5.5% by weight.

In addition, the alkali free glass which concerns on this invention can contain 3-7% of BaO by the oxide basis weight% display. BaO can contribute to improving the chemical resistance and devitrification characteristics of the glass. However, when BaO is contained too high, it may increase the density of the glass and adversely affect the environment. On the other hand, when the content of BaO is too low, the effect of adding BaO is difficult to achieve properly. Thus, the alkali free glass according to the present invention comprises 3 to 7% by weight of BaO. Preferably, BaO is preferably contained in 3 to 6% by weight. More preferably, BaO is contained in 3 to 4% by weight.

Here, it is preferable that the alkali free glass which concerns on this invention contains 9-21 weight% of MgO + CaO + SrO + BaO which is the total content of MgO, CaO, SrO, and BaO. This is because the effect of containing alkaline earth metal oxides in this concentration range can be improved, and the devitrification property may not be degraded. More preferably, the MgO + CaO + SrO + BaO is preferably 11 to 19% by weight. Most preferably, the MgO + CaO + SrO + BaO is 13 to 17% by weight.

Preferably, the alkali free glass according to the invention may have a density of less than 2.5 g / cm ³ . According to this embodiment, the density of the glass may be low and it may be easy to achieve the weight reduction of the glass article. In particular, in a situation where the glass area is gradually increased due to the enlargement of the apparatus to which the glass is applied, when the density of the glass is lowered, it is possible to reduce the warpage phenomenon due to the glass's own load and to reduce the weight of the apparatus to which the glass is applied. In addition, the weight of the glass itself can also be reduced for small portable devices and devices, thereby improving portability.

Also preferably, the alkali free glass according to the present invention may have a coefficient of thermal expansion (CTE) of 3.0 × 10 ⁻⁶ / K to 4.0 × 10 ⁻⁶ / K. According to this embodiment, the thermal expansion coefficient is low, and the thermal shock resistance is excellent. Therefore, even if various heat treatment processes are repeatedly performed on the glass substrate, problems such as heat shrinkage, warpage, and deformation can be prevented from occurring. In addition, since the thermal expansion coefficient is similar to that of the TFT material, it is possible to prevent display defects due to the TFT material and the thermal expansion difference and the like during TFT-LCD manufacture using the glass according to the present invention.

Also preferably, in the alkali free glass according to the present invention, the transformation temperature (T _g ) may exceed 670 ° C. Therefore, in the case of the alkali-free glass according to the present invention, the transition temperature is high, it has high heat resistance, and may have an advantageous effect on heat treatment and molding stability.

Also preferably, the alkali free glass according to the present invention may have an elastic modulus of greater than 77 GPa, and an intrinsic elastic modulus of greater than 31 GPa · cm ³ / g. Therefore, in the case of the alkali-free glass according to the present invention, the elastic modulus and the high modulus of elasticity may be high, and thus may have sufficient mechanical stability, and the sagging problem may be suppressed.

The display device according to the present invention may include the alkali-free glass described above. For example, the display device according to the present invention comprises a glass substrate, such a glass substrate is an alkali-free glass substrate, expressed in terms of weight percent oxide, SiO ₂ 68-75%, B ₂ O ₃ 1-3%, Al ₂ 4 to 13% of O ₃ , 1 to 6% of MgO, 1 to 11% of CaO, 4 to 9% of SrO, and 3 to 7% of BaO, and substantially no alkali metal oxide. Moreover, the density of such an alkali free glass substrate may be less than 2.5 g / cm ³ , and the coefficient of thermal expansion thereof may be 3.0 to 4.0 [× 10 ⁻⁶ / K]. In addition, such an alkali free glass substrate may have a transition temperature of greater than 670 ° C., an elastic modulus of more than 77 GPa, and an intrinsic elastic modulus of more than 31 GPa · cm ³ / g.

In particular, the display device according to the present invention is preferably a liquid crystal display (LCD) device. That is, a liquid crystal display device such as a TFT-LCD includes a glass substrate (panel), which may have the composition and physical properties described above. However, the display device according to the present invention may include various display devices such as a PDP device in addition to the LCD device.

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

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

Referring to Figure 1, first, the raw materials of the respective components contained in the glass are combined to be the target composition (S110). At this time, in the step S110, the alkali metal oxide component is substantially not included, the SiO ₂ is 68 ~ 75%, B ₂ O ₃ 1 ~ 3%, Al ₂ O ₃ is 4 ~ 13 by the oxide weight reference display %, MgO is 1-6%, CaO is 1-11%, SrO is 4-9%, BaO is 3-7%, and the raw material components are combined. Preferably, the step S110 is SiO ₂ 71 ~ 75%, B ₂ O ₃ 1.5 ~ 2.5%, Al ₂ O ₃ 5 ~ 13%, MgO 1 ~ 5%, CaO 1 ~ 8%, Combine the raw materials so that SrO is 4 ~ 6.5% and BaO is 3 ~ 6%. More preferably, the step S110 is 73 to 75% SiO ₂ , 8 to 12% Al ₂ O ₃ , 1 to 3% MgO, 2 to 6% CaO, 4 to 5.5% SrO, BaO is Combine the ingredients so that they contain 3-4%. In addition, the step S110 may be combined with the raw material components to contain 9 to 21% by weight of MgO + CaO + SrO + BaO. More preferably, the step S110 may combine the raw material components to contain 11 to 19% by weight of MgO + CaO + SrO + BaO. Most preferably, the step S110 may be combined with the raw material components to contain 13 to 17% by weight of MgO + CaO + SrO + BaO.

Next, the glass raw material thus combined is heated to a predetermined temperature, for example, 1500-1600 ° C. to melt the glass raw material (S120), and the molten glass is molded (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 S130, that is, the shaping of the glass may be performed by a down draw method or a fusion method.

As such, when the glass is molded in step S130, the molded glass is subjected to a slow cooling process is transferred to a slow cooling furnace (S140). The annealed glass is then cut to the desired size, and further processing such as polishing can be performed and made into a glass article through this series of processes.

As described above, the alkali-free glass produced by the glass manufacturing method according to an embodiment of the present invention, the density may be less than 2.5 g / cm ³ . And the thermal expansion coefficient of the produced alkali free glass may be ^3.0-4.0 [* 10 <^-6> / K]. In addition, the alkali-free glass thus produced may have a transition temperature (T _g ) of greater than 670 ° C., and an elastic modulus and an elastic modulus of elasticity of more than 77 GPa and 31 GPa · cm ³ / g, respectively.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Table 1 shows the glass composition and physical properties of the examples according to the present invention, Table 2 shows the glass composition and physical properties of the comparative example for comparison with these examples.

EXAMPLE

The raw material of each component was combined so that it might become a composition (weight-% basis) as shown in Table 1, and it heated and fuse | melted for 3 hours at the temperature of 1600 degreeC using the platinum crucible. At the time of melting, a platinum stirrer was inserted and stirred for 1 hour to homogenize the glass. Next, the molten glass was slowly cooled at 730 ° C to obtain the glass of each example. In addition, about the obtained glass, the composition was confirmed through the fluorescent X-ray analysis.

In addition, as physical properties for each Example glass, the density, thermal expansion coefficient, transition temperature, elastic modulus and intrinsic elastic modulus were measured by the following method, and the results are shown in Table 1.

(density)

About each Example glass, the density was measured using the Archimedes method.

(Coefficient of Thermal Expansion) (CTE)

About each Example glass, the average coefficent of thermal expansion was measured using the dilatometer.

(Transition temperature) (T _g )

For each Example glass, the transition temperature was measured using differential thermal analysis (DTA) equipment.

(Elastic modulus)

For each Example glass, the modulus of elasticity was measured through a three point bending test.

(Elastic modulus of elasticity)

For each glass, the high modulus of elasticity was obtained by dividing the elastic modulus by the density.

Comparative example

The raw materials of each component were combined so as to have a composition (based on weight percent) as shown in Table 2, and heated and melted at a temperature of 1600 to 1700 ° C. for 3 hours using a platinum crucible. At the time of melting, a platinum stirrer was inserted and stirred for 1 hour to homogenize the glass. Subsequently, the molten glass was slowly cooled at 730 ° C to obtain the glass of each comparative example.

In addition, as the physical properties of each Comparative Example glass, the density, the coefficient of thermal expansion, the transition temperature, the elastic modulus and the high elastic modulus were measured in the same manner as in the above example, and the results are shown in Table 2.

Table 1

TABLE 2

As shown in Table 1 and Table 2, for the glass of Examples (Examples 1 to 10), the density was less than 2.5 g / cm ³ , and the average coefficient of thermal expansion (CTE) was 3.0 to 4.0 (× 10 ⁻⁶ / K) was confirmed. In the case of the embodiment of the glass, T _g has exceeded 670 ℃, Young's modulus and specific modulus was confirmed that each of the more than 77GPa and ³ / g 31GPa · cm.

In contrast, for the glasses of Comparative Examples (Comparative Examples 1 to 10), the density and / or average coefficient of thermal expansion are high and / or T _g , the modulus of elasticity and / or the high modulus of elasticity are significantly lower than those of Examples. Was measured.

Therefore, it can be seen from the comparative results of these examples and the comparative example that, according to the present invention, it is possible to obtain glass having excellent properties, particularly glass having excellent properties as a substrate glass for display. In addition, the glass according to the present invention can be confirmed that the high transition temperature (T _g ) is excellent in heat resistance, high elastic modulus and high modulus of elasticity can ensure mechanical stability and the like.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

Claims (18)

1. In terms of weight percent oxide,

   SiO ₂ 68-75%;

   B ₂ O ₃ 1-3%;

   Al ₂ O ₃ 4-13%;

   MgO 1-6%;

   CaO 1-11%;

   SrO 4-9%; And

   BaO 3 ~ 7%

   And an alkali metal oxide substantially free of alkali free glass.
2. The method of claim 1,

   In terms of weight percent oxide,

   SiO ₂ 71-75%;

   B ₂ O ₃ 1.5-2.5%;

   Al ₂ O ₃ 5-13%;

   MgO 1-5%;

   CaO 1-8%;

   SrO 4-6.5%; And

   BaO 3 ~ 6%

   An alkali free glass comprising a.
3. The method of claim 1,

   In terms of weight percent oxide,

   MgO + CaO + SrO + BaO 9 ~ 21%

   An alkali free glass comprising a.
4. The method of claim 1,

   In terms of weight percent oxide,

   MgO + CaO + SrO + BaO 11 ~ 19%

   An alkali free glass comprising a.
5. The method of claim 1,

   In terms of weight percent oxide,

   SiO ₂ + Al ₂ O ₃ 79 ~ 86%

   An alkali free glass comprising a.
6. The method of claim 1,

   An alkali free glass having a density of less than 2.5 g / cm ³ and a coefficient of thermal expansion of 3.0 × 10 ⁻⁶ / K to 4.0 × 10 ⁻⁶ / K.
7. The method of claim 1,

   The alkali free glass characterized by the transition temperature exceeding 670 degreeC.
8. The method of claim 1,

   An alkali-free glass, wherein the elastic modulus exceeds 77 GPa and the high elastic modulus exceeds 31 GPa · cm ³ / g.
9. A display device comprising the alkali free glass according to any one of claims 1 to 8.
10. The method of claim 9,

    And the display device is a liquid crystal display device.
11. In terms of weight percent oxide,

    SiO ₂ 68-75%;

    B ₂ O ₃ 1-3%;

    Al ₂ O ₃ 4-13%;

    MgO 1-6%;

    CaO 1-11%;

    SrO 4-9%; And

    BaO 3 ~ 7%

    And a step of combining the glass raw materials so as to contain substantially no alkali metal oxides.
12. The method of claim 11,

    The glass raw material combination step,

    In terms of weight percent oxide,

    SiO ₂ 71-75%;

    B ₂ O ₃ 1.5-2.5%;

    Al ₂ O ₃ 5-13%;

    MgO 1-5%;

    CaO 1-8%;

    SrO 4-6.5%; And

    BaO 3 ~ 6%

    An alkali free glass production method characterized by containing a.
13. The method of claim 11,

    The glass raw material combination step,

    In terms of weight percent oxide,

    MgO + CaO + SrO + BaO 9 ~ 21%

    An alkali free glass production method characterized by containing a.
14. The method of claim 11,

    The glass raw material combination step,

    In terms of weight percent oxide,

    MgO + CaO + SrO + BaO 11 ~ 19%

    An alkali free glass production method characterized by containing a.
15. The method of claim 11,

    The glass raw material combination step,

    In terms of weight percent oxide,

    SiO ₂ + Al ₂ O ₃ 79 ~ 86%

    An alkali free glass production method characterized by containing a.
16. The method of claim 11,

    The density of the produced glass is less than 2.5 g / cm ³ , the thermal expansion coefficient of the produced glass is 3.0 × 10 ^-6 / K ~ 4.0 × 10 ^-6 / K characterized in that the alkali-free glass production method.
17. The method of claim 11,

    Method for producing an alkali-free glass, characterized in that the transition temperature of the produced glass exceeds 670 ℃.
18. The method of claim 11,

    The elastic modulus of the produced glass exceeds 77 GPa, and the high elastic modulus of the produced glass exceeds 31 GPa · cm ³ / g.

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