Glass article

Abstract

The present invention provides ultra-thin glass having excellent mechanical strength. In particular, the present invention provides ultra-thin glass having excellent mechanical strength by controlling compressive stress according to the glass composition.

Description

glass items

[0001] The present invention relates to ultra-thin glass having excellent mechanical strength.

[0002]

[0003] Ultra-thin glass is being used in a variety of applications, including semiconductor substrates, display protective cover windows for flexible electronic devices such as foldable or rollable devices, fingerprint sensors, and automotive glazing. Semiconductor substrates, where impact resistance is paramount, require high compressive stress and a deep ion exchange depth, while cover windows for flexible electronic device displays require scratch resistance, impact resistance, and flexibility. Extensive research is being conducted to develop ultra-thin glass that satisfies these properties. For example, Korean Patent Publication No. 10-2020-0014266 discloses an ultra-thin glass article that possesses both high sharp contact resistance and high flexibility.

[0004] When a glass object is bent, tensile stress is applied in the opposite direction of the bend, and this tensile stress can cause the glass object to break. However, if the glass object is subjected to a strong compressive stress that exceeds the tensile stress, breakage due to bending can be minimized. Furthermore, glass objects used in applications such as fingerprint sensors and automotive glazing require excellent scratch and impact resistance due to frequent exposure to the external environment. To improve these properties, high compressive stress is required.

[0005] However, conventional technology cannot predict the compressive stress of glass depending on its composition, making it difficult to manufacture glass products suitable for various applications. In particular, ultra-thin glass is prone to cracking and breaking, so chemical toughening is typically used to enhance the reliability of glass products. If the compressive stress of a glass product after chemical toughening does not meet the required standards, the composition of the glass product must be changed to manufacture the glass product, and the chemical toughening process must be repeated. Therefore, a technology is needed that can reduce time and cost by making it possible to predict the compressive stress of a glass product after chemical toughening based on its composition.

[0006]

[0007] The present invention provides an ultra-thin glass having excellent mechanical strength. In particular, the present invention provides an ultra-thin glass having excellent mechanical strength by controlling compressive stress according to the glass composition.

[0008]

[0009] The present invention provides a glass article in which the compressive stress (y) after chemical toughening satisfies the following equation (1) or (2): (1) y = k[MgO] + b, (2) y = k'[ZnO] + b', where k is 14.95±3.9, b is c[Al2O3] / [SiO2] + d, c is 2,836.07±50.52, d is 390.5±8.6, k' is 38.89±2.5, b' is 853.29±13.2, [MgO] is the content of MgO (mol%) with respect to the total content of the glass article, [ZnO] is the content of ZnO (mol%) with respect to the total content of the glass article, [Al2O3] is the content of Al2O3 (mol%) with respect to the total content of the glass article, and [SiO2] is the content of the glass article The content of SiO2 (mol%) relative to the total content.

[0010]

[0011] The present invention provides an ultra-thin glass having excellent mechanical strength. In particular, the present invention allows for controllable compressive stress depending on the glass composition, thereby facilitating the manufacture of a variety of products suited to ultra-thin glass applications.

[0012]

[0013] The present invention will be described in detail below. However, it is not limited to the following description, and each component may be modified or selectively mixed as needed. Therefore, it should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0014] The glass article of the present invention has a compressive stress (y) after chemical toughening that satisfies the following equation (1) or (2).

[0015] (1) y = k[MgO] + b

[0016] (2) y = k'[ZnO] + b'

[0017] In the above formula,

[0018] k is 14.95±3.9,

[0019] b is c[Al2O3] / [SiO2] + d,

[0020] c is 2,836.07±50.52,

[0021] d is 390.5±8.6,

[0022] k' is 38.89±2.5,

[0023] b' is 853.29±13.2,

[0024] [MgO] is the content of MgO (mol%) relative to the total content of the glass article,

[0025] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article,

[0026] [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article,

[0027] [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

[0028] However, [MgO] + [ZnO] > 0,

[0029] When [ZnO] = 0, the above equation (1) is satisfied,

[0030] When [MgO] = 0 and [Al2O3] / [SiO2] = 0.19, the above equation (2) is satisfied,

[0031] When [MgO] and [ZnO] are not 0, the above equation (1) is satisfied.

[0032] The above chemical toughening can be performed by immersing the glass article in a KNO3 molten salt bath (390°C) for 1 hour.

[0033] The glass article of the present invention comprises SiO2, Al2O3, R2O (R=Li) + , Na + , K + ), R'O (R'=Mg, Ca, Sr, Ba). The glass article of the present invention may further include ZnO, SnO2, CaO, SrO, BaO, and mixtures thereof. The glass article of the present invention does not include highly hygroscopic glass-forming oxides such as B2O3 and P2O5.

[0034] SiO2 is a glass-forming oxide in aluminosilicate glass articles, and plays a role in providing strength to the glass.

[0035] With respect to the total content of the glass article, SiO2 may be included in an amount of 40 to 80 mol%, for example, 55 to 75 mol%. If the content of SiO2 is less than the aforementioned range, the strength of the glass may be reduced, and if it exceeds the aforementioned range, the melting temperature may be increased, which may impair the formability of the glass article.

[0036] Al2O3 functions as an intermediate, charge balancer, or glass-forming oxide in aluminosilicate glass articles, and together with SiO2, it provides strength to the glass. Al2O3 and alkali metal oxide R2O (R=Li) + , Na + , K + ) content affects the structure and properties of aluminosilicate glasses. When Al2O3 is included in the glass composition in excess of R2O, Al2O3 no longer acts as a Si 4+ Not substituted for, Al 5+ , Al 6+ The shape of the glass changes, and the liquid fragility index (m) increases, which can induce crystallization of the glass. In addition, the melting temperature increases as the content of Al2O3 increases, which can hinder the formability of the glass. On the other hand, when there is an excess of R2O than Al2O3, Al ions are substituted for Si, forming AlO4. - , and Li, Na, and K ions are added to AlO4 to play a charge compensation role. - Alkali metal ions that do not participate in chemical toughening can break the Si-O bonds of SiO2, a glass network former, resulting in a decrease in free volume within the glass, which in turn can reduce compressive stress and ion exchange depth.

[0037] The glass article may contain 5 to 25 mol% of Al2O3, for example, 8 to 15 mol%, based on the total content. If the content of Al2O3 is less than the aforementioned range, the strength of the glass may be reduced, and if it exceeds the aforementioned range, crystallization of the glass may be induced or the melting temperature may be increased, thereby hindering the formability of the glass article.

[0038] Alkali metal oxide R2O(R=Li + , Na + , K +) functions as a modifier or charge compensator. R2O destroys the bonds of the glass former, breaking the Si-O bond to form a non-crosslinked oxide, which lowers the melting point and viscosity of the glass and affects the coefficient of thermal expansion of the glass. For example, Na2O and K2O can be used together as alkali metal oxides, in which case acid resistance can be increased.

[0039] The glass article may contain 8 to 30 mol%, for example, 10 to 25 mol%, of an alkali metal oxide, based on the total content of the glass article. For example, the glass article may contain 8 to 20 mol%, for example, 9 to 18 mol%, of Na2O, and 0 to 10 mol%, for example, 0 to 5 mol%, of K2O, based on the total content of the glass article. If the content of Na2O is less than the aforementioned range, the Na content inside the glass may be reduced, thereby reducing the number of alkali metals that can participate in chemical toughening, which may lower the compressive stress. If the content of K2O is more than the aforementioned range, the Si-O bond of SiO2 may be broken, resulting in a reduction in free volume inside the glass, which may lower the compressive stress and ion exchange depth. If the content of K2O is less than the aforementioned range, acid resistance may be weakened, and if it exceeds the aforementioned range, the Na content inside the glass may be reduced, thereby lowering the compressive stress due to chemical toughening.

[0040] Alkaline earth metal oxides R'O (R'=Mg, Ca, Sr, Ba) can affect the Al-avoidance violation, resulting in changes in the internal structure of aluminosilicate glasses.

[0041] For example, the alkaline earth metal compound may include MgO. MgO has a lower atomic number than other alkaline earth metals, which can lower the density, reduce the strain point, and lower the high-temperature viscosity, thereby significantly improving the melting property of the glass. However, among alkaline earth metals, Mg 2+ is Ca2+ , Sr 2+ , Ba 2+ Compared to Al2O3, it has a high ionic field strength and facilitates the formation of 5- and 6-coordinated aluminum. In the aluminosilicate composition, Al2O3 functions as a glass network former or an intermediate oxide to form a strong network structure of the glass, but when it has 5- and 6-coordination numbers, it causes crystallization of the glass. Therefore, when MgO is included, it causes a violation of the Al-avoidance law of the internal structure of the aluminosilicate glass, inducing Si-O-Si and Al-O-Al bonds, so if it is included in large quantities, it can cause crystal precipitation of Mg-Si-O series. In addition, the high ionic field strength reduces the free volume in the glass, resulting in the formation of Na inside the glass. + K has a larger atomic radius than + It becomes difficult for ions to penetrate into the glass, so the substituted K + This can cause a phenomenon in which the compressive stress caused by ions is lowered or the ion exchange depth is lowered. On the other hand, when CaO, SrO, or BaO is included, the internal structure of aluminosilicate glass may have more Si-O-Al bonds than Al-O-Al or Si-O-Si bonds.

[0042] The glass article may contain 0 to 10 mol%, for example 0 to 8 mol%, of an alkaline earth metal oxide relative to the total content of the glass article. For example, the glass article may contain 0 to 10 mol%, for example 0 to 8 mol%, of MgO relative to the total content of the glass article. If the content of MgO is less than the aforementioned range, melting of the glass material may become difficult, and if it exceeds the aforementioned range, the free volume within the glass may be reduced, making chemical toughening difficult.

[0043] ZnO has the same electric field strength as MgO, and when ZnO is included, a large number of Si-O-Al bonds can exist in the internal structure of the aluminosilicate glass. The glass article may include 0 to 10 mol% of ZnO, for example, 0 to 8 mol%, based on the total content of the glass article. When the content of ZnO is less than the aforementioned range, melting of the glass material may become difficult, and when it exceeds the aforementioned range, crystallization may occur.

[0044] For example, the glass article of the present invention may include MgO, ZnO, or a mixture thereof. As another example, the glass article of the present invention may include MgO and ZnO. ZnO has the same tensile strength as MgO and a similar glass structure, and thus plays a similar role in the expression of glass properties. However, as the ZnO content increases, a devitrification phenomenon may occur during glass manufacturing, and therefore, the ZnO content included in the glass article is preferably 50 mol% or less of the MgO content, for example, 25 mol% or less, or in another example, 10 mol% or less.

[0045] The glass article of the present invention comprises, based on the total content of the glass article, 40 to 80 mol% of SiO2, 5 to 25 mol% of Al2O3, 8 to 20 mol% of Na2O, 0 to 10 mol% of K2O, 0 to 10 mol% of MgO, and 0 to 10 mol% of ZnO.

[0046] The glass article of the present invention may further include SnO2, CaO, SrO, BaO, and mixtures thereof in addition to the above-described oxides. For example, the glass article may include SnO2 in an amount of 0 to 0.5 mol%, for example, 0 to 0.3 mol%, CaO in an amount of 0 to 10 mol%, for example, 0 to 8 mol%, SrO in an amount of 0 to 10 mol%, for example, 0 to 5 mol%, and BaO in an amount of 0 to 10 mol%, for example, 0 to 8 mol%, based on the total content of the glass article.

[0047] In the present invention, through consideration and experimentation of the following matters, a relationship was derived that can derive the compressive stress of alkali aluminosilicate glass from the content of MgO or ZnO.

[0048] MgO promotes ion exchange, but also causes violation of the Al-avoidance law in the internal structure of the glass, causing Si-O-Si and Al-O-Al bonds. Therefore, if it is included in large quantities, it can cause crystal precipitation of the Mg-Si-O series. In addition, high ionic field strength reduces the free volume within the glass, resulting in Na contained within the glass. + K has a larger atomic radius than + It becomes difficult for ions to penetrate into the glass, so the substituted K + This can cause a decrease in ion-induced compressive stress or a decrease in ion exchange depth. Thus, MgO can significantly affect chemical toughening.

[0049] Additionally, the glass structure of alkali aluminosilicate glass is greatly influenced by the [Al2O3 / SiO2] ratio.

[0050] The present invention demonstrates that the chemical toughening of alkali aluminosilicate glass is closely related to the internal structure of the glass, allowing compressive stress to be calculated based on changes in the glass structure. This suggests that, based on a thorough understanding of the internal structure of the glass, it is possible to calculate compressive stress from the composition of alkali aluminosilicate glass under given conditions.

[0051] Meanwhile, in relation to the relationship between Al and R2O in aluminosilicate glasses, the Anderson-Stuart model related to ion conduction has been proposed based on the activation energy and Coulomb energy required for ion conduction, and the influence of glass structure deformation on ion conduction is known. These facts are more closely related to the ion exchange depth related to ion movement than to the cause of compressive stress generation in ion exchange-based chemical toughening. Recently, an explanation approaching the glass structure for the cause of compressive stress has been attempted, but although the tendency of compressive stress for glasses that have undergone a chemical toughening process could be identified, accurate result values ​​could not be derived.

[0052] In the present invention, it was taken into account that chemical toughening is achieved through ion exchange and that compressive stress can be generated by changes in the glass structure due to ions exchanged during ion exchange.

[0053] The composition of glass was classified into glass network former, glass network intermediate, and glass network modifier according to the classification system (Sun classification) proposed by Kuan-Han Sun in 1947. In the present invention, ionic conduction by glass network modifier according to the Al2O3-R2O relationship and the Anderson-Stuart model was considered. In addition, the Al2O3-SiO2 relationship and the Al2O3-R2O relationship were considered in consideration of the cause of compressive stress generation. Comprehensively considering the above facts, the glass composition elements classified by Sun classification were divided according to absolute amount and ratio and an experiment was conducted. As a result, it was possible to identify factors that can significantly affect ionic conduction and glass structure, and it was confirmed that the relationship between them was linear and that the compressive stress could be sufficiently accurately calculated using only the composition of the glass.

[0054] For example, the glass article of the present invention has a compressive stress (y) after chemical toughening that satisfies the following equation (1).

[0055] (1) y = k[MgO] + b

[0056] In the above formula,

[0057] k is 14.95±3.9,

[0058] b is c[Al2O3] / [SiO2] + d,

[0059] c is 2,836.07±50.52,

[0060] d is 390.5±8.6,

[0061] [MgO] is the content of MgO (mol%) relative to the total content of the glass article,

[0062] [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article,

[0063] [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

[0064] However, [MgO] + [ZnO] > 0,

[0065] When [ZnO] = 0, the above equation (1) is satisfied,

[0066] When [MgO] = 0 and [Al2O3] / [SiO2] = 0.19, the following equation (2) is satisfied,

[0067] When [MgO] and [ZnO] are not 0, the above equation (1) is satisfied.

[0068] The above chemical toughening can be performed by immersing the glass article in a KNO3 molten salt bath (390°C) for 1 hour.

[0069] In the present invention, the compressive stress (y) of the glass article is proportional to [MgO] and [Al2O3] / [SiO2]. Depending on [MgO] and [Al2O3] / [SiO2], the atomic structure and the number of alkali metal ions inside the glass change, which in turn affects the compressive stress.

[0070] As another example, the glass article of the present invention has a compressive stress (y) after chemical toughening that satisfies the following equation (2).

[0071] (2) y = k'[ZnO] + b'

[0072] In the above formula,

[0073] k' is 38.89±2.5,

[0074] b' is 853.29±13.2,

[0075] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article.

[0076] However, [MgO] + [ZnO] > 0,

[0077] When [ZnO] = 0, the above equation (1) is satisfied,

[0078] When [MgO] = 0 and [Al2O3] / [SiO2] = 0.19, the above equation (2) is satisfied,

[0079] When [MgO] and [ZnO] are not 0, the above equation (1) is satisfied.

[0080] The above chemical toughening can be performed by immersing the glass article in a KNO3 molten salt bath (390°C) for 1 hour.

[0081] In the present invention, the compressive stress (y) of the glass article is proportional to [ZnO]. Depending on [ZnO], the atomic structure and the number of alkali metal ions within the glass change, which in turn affects the compressive stress.

[0082] For example, the glass article of the present invention satisfies the following equation (3).

[0083] (3) [ZnO] + [Y2O3] + [TiO2] + [ZrO2] + [Nb2O5] ≤ [MgO] / 2

[0084] In the above formula,

[0085] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article,

[0086] [Y2O3] is the content of Y2O3 (mol%) relative to the total content of the glass article,

[0087] [TiO2] is the content of TiO2 (mol%) relative to the total content of the glass article,

[0088] [ZrO2] is the content of ZrO2 (mol%) relative to the total content of the glass article,

[0089] [Nb2O5] is the content of Nb2O5 (mol%) relative to the total content of the glass article,

[0090] [MgO] is the content of MgO (mol%) relative to the total content of the glass article.

[0091] For example, the glass article of the present invention satisfies the following equation (4).

[0092] (4) [Al2O3] / [R2O] < 1

[0093] In the above formula,

[0094] [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article,

[0095] [R2O] is the content of R2O (mol%) relative to the total content of the glass article,

[0096] R is one or more elements selected from the group consisting of Li, Na, and K.

[0097] Al2O3 and alkali metal oxide R2O(R=Li + , Na + , K + ) content affects the structure and properties of aluminosilicate glasses. When Al2O3 is included in the glass composition in excess of R2O, Al2O3 no longer acts as a Si4+ Not substituted for, Al 5+ , Al 6+ The shape of the glass changes, and the liquid fragility index (m) increases, which can induce crystallization of the glass. In addition, the melting temperature increases as the content of Al2O3 increases, which can hinder the formability of the glass. On the other hand, when there is an excess of R2O than Al2O3, Al ions are substituted for Si, forming AlO4. - , and Li, Na, and K ions are added to AlO4 to play a charge compensation role. - In combination with, alkali metals that do not participate in chemical toughening can break the Si-O bonds of SiO2, which is a glass network former, resulting in a decrease in free volume inside the glass, which can result in a decrease in compressive stress and ion exchange depth. When [Al2O3] / [R2O] ≤ 1 is satisfied, excellent compressive stress can be secured. In particular, when [Al2O3] / [R2O] < 0.8, or for example, 0.5 < [Al2O3] / [R2O] < 0.7 is satisfied, not only excellent compressive stress but also high formability can be secured.

[0098] For example, the glass article of the present invention satisfies the following equation (5).

[0099] (5) [GNI] / [SiO2] < 0.5

[0100] In the above formula,

[0101] R is one or more elements selected from the group consisting of Li, Na, and K,

[0102] [GNI] is the content (mol%) of GNI (glass network intermediate) relative to the total content of the glass article, GNI is an intermediate oxide with an e value of 60 to 80, e=E / n, and E is the content of 1 mole of oxide (MO y / x) is the dissociation energy required to completely decompose, and n is the oxygen coordination number of the M atom. For example, GNI may contain oxides of Al, Zn, Ti, Nb, Mn, Fe, Zr, Mo, W, and Ta.

[0103] The GNI and SiO2 contents affect the structure and properties of aluminosilicate glasses. As the [GNI] / [SiO2] ratio increases, the number of bridging oxygens decreases and the non-bridging oxygens increase. An increase in non-bridging oxygen can lead to a decrease in free volume within the glass, which in turn can reduce compressive stress. When the [GNI] / [SiO2] ratio ≤ 0.5 is satisfied, excellent compressive stress can be ensured.

[0104] For example, the glass article of the present invention satisfies the following equation (6).

[0105] (6) [ZnO] < [MgO] / 2

[0106] In the above formula,

[0107] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article,

[0108] [MgO] is the content of MgO relative to the total content of the glass article.

[0109] The glass article of the present invention has a compressive stress of 300 to 1,300 MPa, for example, 500 to 1,200 MPa, an ion exchange depth of 50% or less of the total glass thickness, for example, 45% or less, a thickness of 500 μm or less, for example, 30 to 300 μm, a coefficient of thermal expansion of 4.0 ppm / C or more, for example, 6 to 11 ppm / C, and a pencil hardness of 3H or more. In addition, the glass article of the present invention has a minimum radius of curvature of 3 mm or less, for example, 1.5 mm or less, or another example, 0.3 to 3 mm, or another example, 0.3 to 1.5 mm. When the minimum radius of curvature of the glass article satisfies the above-mentioned range, it is suitable for application to a flexible display according to the development of form factors.

[0110]

[0111] Hereinafter, the present invention will be described in more detail through experimental examples. However, the following examples are intended only to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0112]

[0113] [Experimental Example 1-28]

[0114] Glass compositions for each experimental example were prepared according to Table 1-5 below. Glass articles prepared using the glass compositions for each experimental example were toughened using the following method, and their physical properties were measured, which are listed in Table 1-5 below.

[0115]

[0116] chemical toughening

[0117] Glass articles manufactured with the glass composition of each experimental example were immersed in a KNO3 molten salt bath (390°C) for 1 hour.

[0118]

[0119] Compressive stress and ion exchange depth

[0120] For each glass article after chemical toughening, the compressive stress and ion exchange depth were measured according to ASTM 1422C-99 and ASTM 1279.19779 (measuring device: FSM-6000 from Orihara, Tokyo Japan).

[0121]

[0122] Pen drop test

[0123] For each glass product in the experiment, a pen was dropped 10 mm from the surface, and the presence or absence of cracks on the glass surface was checked. If no cracks occurred, the pen was dropped from a higher position by 5 mm in increments, and the highest height without cracks was measured. A score of 30 mm or higher was evaluated as pass, and a score of less than 30 mm was evaluated as fail.

[0124]

[0125] Bending Test

[0126] Using a universal testing machine, the glass object of each experimental example was placed between the upper and lower plate surfaces of the UTM, and the gap (bending radius) between the upper and lower plates just before the glass object broke was measured while lowering the upper plate. A bending radius of 1.5 mm or less was evaluated as pass, and a bending radius exceeding 1.5 mm was evaluated as fail.

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133] As shown in Table 1-5 above, the glass article of Experimental Example 1-24 satisfies the composition according to the present invention, and furthermore, the compressive stress (y) after chemical toughening satisfies Equation (1) or (2), so even if the glass article is manufactured and chemically toughened and the physical properties are not evaluated, the physical properties of the glass article can be predicted with the compressive stress value calculated according to Equation (1) or (2).

[0134] On the other hand, the glass articles of Experimental Examples 25-28 do not satisfy the composition according to the present invention, and the glass articles of Experimental Examples 25-27 have a high content of MgO, so K + Chemical toughening, in which ions penetrate into the glass, did not proceed, and the glass article of Experimental Example 28 had a high ZnO content, so crystals were precipitated during the manufacturing process, making it impossible to manufacture the glass article.

[0135]

[0136] The present invention provides an ultra-thin glass having excellent mechanical strength.

[0137]

Claims

1. With respect to the total content of the glass article, it contains SiO240 to 80 mol%, Al2O35 to 25 mol%, Na2O8 to 20 mol%, K2O0 to 10 mol%, MgO0 to 10 mol%, and ZnO0 to 10 mol%, A glass article having a compressive stress (y) after chemical toughening satisfying the following equation (1) or (2): (1) y = k[MgO] + b (2) y = k'[ZnO] + b' In the above formula, k is 14.95±3.9, b is c[Al2O3] / [SiO2] + d, c is 2,836.07±50.52, d is 390.5±8.6, k' is 38.89±2.5, b' is 853.29±13.2, [MgO] is the content of MgO (mol%) relative to the total content of the glass article, [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article, [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article, [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article, [MgO] + [ZnO] > 0, When [ZnO] = 0, the above equation (1) is satisfied, When [MgO] = 0 and [Al2O3] / [SiO2] = 0.19, the above equation (2) is satisfied, When [MgO] and [ZnO] are not 0, the above equation (1) is satisfied.

2. In paragraph 1, a glass article satisfying the following formula (3): (3) [ZnO] + [Y2O3] + [TiO2] + [ZrO2] + [Nb2O5] ≤ [MgO] / 2 In the above formula, [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article, [Y2O3] is the content of Y2O3 (mol%) relative to the total content of the glass article, [TiO2] is the content of TiO2 (mol%) relative to the total content of the glass article, [ZrO2] is the content of ZrO2 (mol%) relative to the total content of the glass article, [Nb2O5] is the content of Nb2O5 (mol%) relative to the total content of the glass article, [MgO] is the content of MgO (mol%) relative to the total content of the glass article.

3. In paragraph 1, a glass article satisfying the following formula (4): (4) [Al2O3] / [R2O] ≤ 1 In the above formula, [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article, [R2O] is the content of R2O (mol%) relative to the total content of the glass article, R is one or more elements selected from the group consisting of Li, Na, and K.

4. In paragraph 1, a glass article satisfying the following formula (5): (5) [GNI] / [SiO2] < 0.5 In the above formula, [GNI] is the content (mol%) of GNI (glass network intermediate) relative to the total content of the glass article, GNI is an intermediate oxide with an e value of 60 to 80, e=E / n, and E is the content of 1 mole of oxide (MO y / x ) is the dissociation energy required to completely decompose, n is the oxygen coordination number of the M atom, [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

5. In paragraph 1, a glass article satisfying the following formula (6): (6) [ZnO] < [MgO] / 2 In the above formula, [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article, [MgO] is the content of MgO relative to the total content of the glass article.

6. A glass article comprising, in the first paragraph, SnO20 to 0.5 mol%, CaO 0 to 10 mol%, SrO 0 to 10 mol%, and BaO 0 to 10 mol% with respect to the total content of the glass article.

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