glass

Abstract

The present invention provides improved optical properties while suppressing cracking. Glass (10) has an internal transmittance of 85% or more with respect to light having a wavelength of 450 nm and in terms of a thickness of 10 mm, has a d-line refractive index nd of 2.050 or more, and contains at least one of TiO2 and Li2O on an oxide basis. In terms of mol% on an oxide basis, the glass contains Bi2O3 at 20.0% to 40.0%; SiO2 at 0% to 5.0%; Al2O3 at 0% to 5.0%; B2O3 at 15.0% to 35.0%; P2O5 at more than 0% but no more than 20.0%; Nb2O5 at 0% to 12.0%; TeO2 at 1.0% to 30.0%; ZnO at 0% to 20.0%; ZrO2 at 0% to 10.0%; TiO2 at 0% to 20.0%; WO3 at 0% to 7.5%' RO at 0% to 7.0%; and R'2O at 0% to 10.0%. The parameter (A) represented by formula (1) is 0.95 or more.

Description

Glass

[0001] The present invention relates to glass.

[0002] In recent years, there has been a demand for glass having optical properties of high transmittance and high refractive index. For example, in Patent Documents 1 and 2, glass having high transmittance and high refractive index is described as a light guide plate of a wearable device such as a head-mounted display that realizes AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), and the like.

[0003] International Publication No. 2022 / 059355 International Publication No. 2023 / 120415

[0004] However, glass having high transmittance and high refractive index may be prone to cracking.

[0005] An object of the present invention is to provide glass capable of suppressing cracking while improving optical properties.

[0006] The glass according to the present disclosure has an internal transmittance of 85% or more with respect to light having a wavelength of ｄ 450 nm converted to a thickness of 10 mm, and a refractive index n ｄ of 2.050 or more, contains at least one of ２ TiO ２ and ２ Li ２ O, and in terms of molar percentage based on oxides, ２ Bi ２ O ３ : 20.0% to 40.0% ２ SiO ２ : 0% to 5.0% ２ Al ２ O ３ : 0% to 5.0% ２ B ２ O ３ : 15.0% to 35.0% ２ P ２ O ５ : more than 0% to 20.0% ２ Nb ２ O ５ : 0% to 12.0% ２ TeO ２ : 1.0% to 30.0% ZnO: 0% to 20.0% ２ ZrO ２ : 0% to 10.0% <000\0017>TiO ２ : 0% to 20.0% ３ WO ３ : 0% to 7.5% RO: 0% to 7.0% ２ R’ ２O: Contains 0% to 10.0%, and parameter A, represented by formula (1), is 0.95 or higher.

[0007] A = ([B ２ O ３ ] × 2 + [P ２ O ５ ] × 2 + [Nb ２ O ５ ] × 2 + [ZrO ２ ] + [TiO ２ ] + [WO ３ ] + [RO] + [R' ２ O] × 2) / ([Bi ２ O ３ ] × 2 + [Al ２ O ３ ] × 2 + [SiO ２ ] + [TeO ２ ]+[ZnO]) ...(1)

[0008] Here, [ ] represents the content of each component in parentheses in mole percent based on oxide, RO is the total content of MgO, CaO, SrO, and BaO, and R' ２ O is Li ２ O, Na ２ O, K ２ This is the total amount of oxygen (O).

[0009] According to the present invention, cracking can be suppressed while improving optical properties.

[0010] Figure 1 is a schematic diagram of the glass according to this embodiment. Figure 2 is a cross-sectional view of the glass according to this embodiment when it is formed into a glass plate.

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the present invention is not limited to these embodiments, and if there are multiple embodiments, they may be constructed by combining each embodiment. Furthermore, numerical values ​​include a rounding range. Also, a numerical range represented by "~" means a numerical range that includes the numbers before and after "~" as the lower and upper limits, and the same meaning applies when "~" is used hereafter. In addition, in this embodiment, the lower and upper limits can be combined as appropriate. That is, for example, if multiple lower limits and multiple upper limits are listed for a certain parameter, the parameter may have any value selected from the multiple listed lower limits as its lower limit, and any value selected from the multiple listed upper limits as its upper limit.

[0012] (Glass) Figure 1 is a schematic diagram of the glass according to this embodiment. As shown in Figure 1, the glass 10 according to this embodiment is a plate-shaped glass plate, but the shape of the glass 10 is not limited to a plate shape and may be arbitrary. In this embodiment, the glass 10 is used as a light guide plate. More specifically, the glass 10 is used as a light guide plate for a head-mounted display. A head-mounted display is a display device (wearable device) that is worn on a person's head. However, the use of the glass 10 is arbitrary and is not limited to being used as a light guide plate, nor is it limited to being used in a head-mounted display.

[0013] (Composition) The composition of glass 10 is described below.

[0014] (Parameter A) The parameter A of the glass 10 shall be as shown in the following equation (1).

[0015] A = ([B ２ O ３ ] × 2 + [P ２ O ５ ] × 2 + [Nb ２ O ５ ] × 2 + [ZrO ２ ] + [TiO ２ ] + [WO ３ ] + [RO] + [R'２ O] × 2) / ([Bi ２ O ３ ] × 2 + [Al ２ O ３ ] × 2 + [SiO ２ ] + [TeO ２ ]+[ZnO]) ...(1)

[0016] Here, [] indicates the content of each component in the brackets in mole percent based on oxide. That is, for example, in mole percent based on oxide, the content of oxide A contained in glass 10. ｘ O ｙ The content of (A is an element that makes up the oxide, and x and y are arbitrary integers) is [A ｘ O ｙ This is expressed as follows: The content here refers to the amount of oxide A relative to the total amount of glass 10, expressed in mol% based on oxides. ｘ O ｙ This refers to the ratio of the content of each element. Furthermore, R refers to Mg, Ca, Sr, and Ba among the divalent metals, and RO refers to the oxides of R, namely MgO, CaO, SrO, and BaO. Also, in formula (1), [RO] refers to the ratio of RO content to the total content of glass 10 in mol% expression based on oxides, namely the total content of MgO, CaO, SrO, and BaO. Furthermore, R' refers to Li, Na, and K among the divalent metals, and R' ２ O is an oxide of R', i.e., Li ２ O, Na ２ O, K ２ It refers to O. Also, [R' in equation (1) ２ O] is the molar percentage of the total glass 10, based on oxides. ２ This refers to the ratio of O content, i.e., Li ２ O, Na ２ O, K ２ This refers to the total amount of oxygen (O).

[0017] The parameter A of the glass 10 is 0.95 or more, preferably 1.00 or more, more preferably 1.05 or more, further preferably 1.10 or more, even more preferably 1.15 or more, particularly preferably 1.20 or more, and most preferably 1.25 or more. By setting the parameter A to 0.95 or more, the Young's modulus of the glass 10 can be increased and cracking can be suppressed. The upper limit of the parameter A is not particularly limited, but for example, the upper limit of the parameter A is 1.80 or less.

[0018] (Parameter B) Let the parameter B of the glass 10 be as shown in the following formula (2).

[0019] B = ([B ２ O ３ ] × 0.9189 + [SiO ２ ] × 0.4645 - [Bi ２ O ３ ] × 0.5722 + [Al ２ O ３ ] × 0.0274 + [P ２ O ５ ] × 0.9699 - [Nb ２ O ５ ] × 0.6676 - [TeO ２ ] × 0.0488 + [ZnO] × 0.3739 + [ZrO ２ ] × 0.0383 - [TiO ２ ] × 1.4225 - [WO ３ ] × 1.4894 + [Li ２ O] × 0.4638 + ([Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ ]) × 0.4376 - [MgO] × 6.2400 - [SrO] × 11.0293 - [BaO] × 19.9319) ··· (2)

[0020] Here, [ ] means the content in mol% based on the oxide of each component within the brackets. For parameter B of glass 10, it is preferably 10 or more, more preferably 20 or more, further preferably 25 or more, even more preferably 30 or more, even more preferably 35 or more, still more preferably 37 or more, particularly preferably 39 or more, and most preferably 40 or more. By making parameter B within this range, the transmittance of glass 10 can be appropriately increased. The upper limit of parameter B is not particularly limited, but for example, the upper limit of parameter B is 55.0 or less. In this case, [TeO ２ is preferably 1.0 or more.

[0021] (Parameter C) Let parameter C of glass 10 be as shown in the following formula (3).

[0022] C = ([Bi ２ O ３ × 0.0158 - [SiO ２ × 0.0032 - [B ２ O ３ × 0.0134 - [Al ２ O ３ × 0.0014 - [P ２ O ５ × 0.0121 + [Nb ２ O ５ × 0.0092 - [TeO ２ × 0.0005 + [ZnO] × 0.0003 - [ZrO ２ × 0.0014 + [TiO ２ × 0.0025 + [WO ３ × 0.0032 - [Li ２ O] × 0.0029) ··· (3)

[0023] Here, [] indicates the content of each component in parentheses in mole percent based on oxide. The parameter C of glass 10 is preferably 0.00 or higher, more preferably 0.01 or higher, even more preferably 0.02 or higher, even more preferably 0.03 or higher, especially preferably 0.04 or higher, particularly preferably 0.05 or higher, and most preferably 0.06 or higher. By having parameter C within this range, the refractive index of glass 10 can be appropriately increased. There is no particular upper limit to parameter C, but the upper limit of parameter C is, for example, 0.20 or lower.

[0024] When the glass 10 has a parameter A of 0.95 or higher, a parameter B of 10 or higher, and a parameter C of 0.00 or higher (preferably a parameter A of 1.10 or higher, a parameter B of 35 or higher, and a parameter C of 0.05 or higher), the internal transmittance τ converted to a 10 mm thickness is ４５０ This is particularly preferable because it easily satisfies the requirements of 90% or more, a refractive index nd of 2.070 or more, and a Young's modulus of 80 GPa or more simultaneously, and is also advantageous in suppressing crystallization and phase separation. Thus, while increasing parameter A improves rigidity and suppresses cracking, maintaining parameter B above a predetermined level avoids transmission loss due to absorption in the blue region, and setting parameter C above a predetermined level secures a high refractive index region. Therefore, a design in which all three parameters A, B, and C are within a favorable range is particularly preferable.

[0025] (Bi ２ O ３ ) Bi ２ O ３ This is a component that constitutes the network structure of glass and is an essential component of the glass of this disclosure. Glass 10 is expressed in molar percentage on an oxide basis, Bi ２ O ３ The content is 20.0% to 40.0%. In glass 10, Bi ２ O ３ By having a content of 20.0% or more, the refractive index can be greatly improved while lowering the glass transition temperature Tg. ２ O ３The content of is more preferably 22.0% or more, even more preferably 24.0% or more, even more preferably 25.0% or more, even more preferably 26.0% or more, particularly preferably 28.0% or more, and most preferably 29.0% or more. Also, in glass 10, Bi ２ O ３ If a large amount of is included, crystallization is more likely to occur during manufacturing, which may not only raise the devitrification temperature but also decrease the transmittance and Young's modulus, and increase the density. Therefore, Bi ２ O ３ The content of is more preferably 38.0% or less, even more preferably 36.0% or less, even more preferably 35.0% or less, even more preferably 34.0% or less, particularly preferably 32.0% or less, and most preferably 31.0% or less.

[0026] (SiO ２ ) SiO ２ SiO is a component that makes up the network structure of glass, and its inclusion can improve chemical durability such as acid resistance, alkali resistance, and water resistance, but it is an optional component because it may cause deterioration of the meltability of the raw material and a decrease in refractive index and Young's modulus. Glass 10 is expressed in mole percent on an oxide basis, and SiO ２ The content is 0.0% to 5.0%, and in glass 10, SiO ２ By limiting the content to 5.0% or less, the decrease in refractive index can be suppressed. In glass 10, SiO ２ The content of SiO is more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not present). Note that 0% (not present) means that it is acceptable to include it as an unavoidable impurity. ２ If it contains SiO ２ The content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0027] (Al ２ O ３ ) Al ２ O ３Al is a component that makes up the network structure of glass, and its inclusion can improve chemical durability such as acid resistance and water resistance, but it is an optional component because it may cause deterioration of the meltable properties of the raw material and a decrease in refractive index. Glass 10 is expressed in molar percentage based on oxide, and Al ２ O ３ The content is 0.0% to 5.0%, and in glass 10, Al ２ O ３ By keeping the content of 5.0% or less, the decrease in refractive index can be suppressed. In glass 10, Al ２ O ３ The content of is more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not present). Note that 0% (not present) means that it is acceptable to have it present as an unavoidable impurity. Al ２ O ３ If it contains Al ２ O ３ The content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0028] (B ２ O ３ ) B ２ O ３ This is a component that constitutes the network structure of the glass and is an essential component of the glass of this disclosure. Glass 10 is expressed in mol% on an oxide basis as B ２ O ３ The content is 15.0% to 35.0%. In glass 10, B ２ O ３ Having a content of 15.0% or more improves the meltability of the glass and suppresses the formation of heterogeneous substrates in the melt. Furthermore, it can improve transmittance and Young's modulus and reduce density. B ２ O ３The content of is more preferably 17.0% or more, even more preferably 19.0% or more, even more preferably 20.0% or more, even more preferably 21.0% or more, especially preferably 23.0% or more, especially preferably 24.0% or more, and most preferably 25.0% or more. Also, in glass 10, B ２ O ３ If a large amount of is included, volatilization will occur during manufacturing, which will not only worsen the homogeneity of the glass but may also reduce its transmittance and refractive index. Therefore, B ２ O ３ The content of is more preferably 34.0% or less, even more preferably 32.0% or less, even more preferably 30.0% or less, particularly preferably 29.0% or less, and most preferably 28.0% or less.

[0029] (P ２ O ５ ) P ２ O ５ P is a component that constitutes the network structure of glass and is an essential component of the glass of this disclosure. Glass 10 is expressed in mol% on an oxide basis, P ２ O ５ The content of is greater than 0.0% to 20.0% (i.e., higher than 0.0% and 20.0% or less). In glass 10, P ２ O ５ Having a content of over 0% improves the meltability of the glass and suppresses the formation of heterogeneous substrates in the melt. Furthermore, it can improve transmittance and Young's modulus and reduce density. ２ O ５ The content of is more preferably 3.0% or more, even more preferably 5.0% or more, even more preferably 6.0% or more, particularly preferably 7.0% or more, and most preferably 8.0% or more. Also, in glass 10, P ２ O ５ If a large amount of P is included, volatilization will occur during manufacturing, which will not only worsen the homogeneity of the glass but may also reduce its transmittance and refractive index. Therefore, P ２ O ５The content of is more preferably 18.0% or less, even more preferably 16.0% or less, even more preferably 15.0% or less, even more preferably 14.0% or less, particularly preferably 12.0% or less, and most preferably 11.0% or less.

[0030] [B ２ O ３ ] and [P ２ O ５ The total amount and ratio of [B] affect the meltableness, clarity, and homogeneity of the glass 10, as well as the mechanical and optical properties of the glass 10. The glass 10 is expressed in mol% based on oxide, with [B] ２ O ３ ] + [P ２ O ５ By setting the ratio to 33.5% to 38.0%, the formation of heterogeneous substrates in the melt is suppressed, while the transmittance τ ４５０ It is particularly preferable because it is easy to maintain a Young's modulus of 80 GPa or more and a ratio of 90% or more. Furthermore, [B ２ O ３ ] + [P ２ O ５ By setting this range, the increase in specific gravity and decrease in refractive index can be suppressed, contributing to achieving both homogeneity and processing stability of the glass. Furthermore, the glass 10 is expressed in mol% based on oxide, B ２ O ３ and P ２ O ５ P relative to the total content ２ O ５ The ratio of the content ([P ２ O ５ ] / ([B ２ O ３ ] + [P ２ O ５ Setting the ratio to be greater than 0.22 and less than 0.32 is particularly preferable because it improves the melting properties, clarity, and homogeneity of the glass 10, as well as the mechanical and optical properties of the glass 10.

[0031] (Nb ２ O ５ ) Glass 10 is Nb ２ O ５ It is not necessary to include it, but it is preferable to include it from the viewpoint of improving refractive index and Young's modulus. Glass 10 is expressed in mole percent on an oxide basis, and Nb２ O ５ The content is 0.0% to 12.0%. In glass 10, Nb ２ O ５ By including Nb, the refractive index and Young's modulus can be improved. In glass 10, Nb ２ O ５ The content of is more preferably 1.0% or more, even more preferably 2.0% or more, even more preferably 3.0% or more, particularly preferably 4.0% or more, and most preferably 5.0% or more. In addition, in glass 10, Nb ２ O ５ If a large amount of Nb is included, crystallization is more likely to occur during manufacturing, which not only raises the devitrification temperature but may also decrease transmittance and increase density. Therefore, Nb ２ O ５ The content of is more preferably 11.0% or less, even more preferably 10.0% or less, even more preferably 9.0% or less, particularly preferably 8.5% or less, and most preferably 8.0% or less.

[0032] (TeO ２ ) TeO ２ TeO is an essential component of the glass of this disclosure from the viewpoint of improving transmittance and refractive index. Glass 10 is expressed in mole percent on an oxide basis, and TeO ２ The content is 1.0% to 30.0%. In glass 10, TeO ２ By including TeO, the transmittance and refractive index can be improved. In glass 10, TeO ２ The content of is more preferably 1.5% or more, even more preferably 2.0% or more, even more preferably 2.5% or more, particularly preferably 3.0% or more, and most preferably 3.5% or more. Also, in glass 10, TeO ２ If a large amount of TeO is included, volatilization will occur during manufacturing, which will not only worsen the homogeneity of the glass but may also significantly reduce its transmittance, refractive index, and especially its Young's modulus. Therefore, TeO ２ The content of is more preferably 25.0% or less, even more preferably 20.0% or less, even more preferably 15.0% or less, especially preferably 12.0% or less, particularly preferably 10.0% or less, and most preferably 9.0% or less.

[0033] (ZnO) Glass 10 may be free of ZnO, but it is preferable to include it from the viewpoint of improving the refractive index. The ZnO content of glass 10 is 0.0% to 20.0% in molar percentage based on oxide. The refractive index can be improved by including ZnO in glass 10. In glass 10, the ZnO content is more preferably 2.0% or more, even more preferably 3.0% or more, even more preferably 4.0% or more, particularly preferably 5.0% or more, and most preferably 6.0% or more. Furthermore, if glass 10 contains a large amount of ZnO, the melting properties of the raw material may deteriorate and the density may increase. Therefore, the ZnO content is more preferably 18.0% or less, even more preferably 16.0% or less, even more preferably 15.0% or less, even more preferably 14.0% or less, particularly preferably 13.0% or less, particularly preferably 12.0% or less, and most preferably 11.0% or less.

[0034] (ZrO ２ ) Glass 10 is ZrO ２ It is not necessary to contain it, but it is preferable to include it. Glass 10 is expressed in mole percent based on oxide, ZrO ２ The content is 0.0% to 10.0%. In glass 10, ZrO ２ By including ZrO, chemical durability such as acid resistance, alkali resistance, and water resistance, as well as Young's modulus and refractive index, can be improved. In glass 10, ZrO ２ The content of is more preferably 0.50% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, particularly preferably 2.0% or more, and most preferably 2.5% or more. Also, in glass 10, ZrO ２ If a large amount of ZrO is included, the melting properties of the raw material will deteriorate, crystallization will occur more easily, and there is a risk that the devitrification temperature will rise and the density will increase. ２ The content of is more preferably 9.0% or less, even more preferably 8.0% or less, even more preferably 7.0% or less, especially preferably 6.0% or less, particularly preferably 5.0% or less, and most preferably 4.0% or less.

[0035] (TiO２ ) Glass 10 is TiO ２ and Li ２ It contains at least one of O. Glass 10 is TiO ２ It is not necessary to include it, but it is preferable to include it from the viewpoint of improving refractive index and Young's modulus. Glass 10 is expressed in mole percent on an oxide basis as TiO ２ The content is 0.0% to 20.0%. In glass 10, TiO ２ By including TiO, chemical durability such as acid resistance, alkali resistance, and water resistance, as well as Young's modulus and UV solarization resistance can be improved. Furthermore, it is possible to increase the refractive index while suppressing an increase in density. In glass 10, TiO ２ The content of is preferably more than 0.0%, more preferably 0.50% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, especially preferably 2.0% or more, particularly preferably 2.5% or more, and most preferably 3.0% or more. Also, in glass 10, TiO ２ If a large amount of TiO is included, the melting properties of the raw material will deteriorate, and the transmittance may decrease. Therefore, ２ The content of is more preferably 15.0% or less, even more preferably 13.0% or less, even more preferably 12.0% or less, especially preferably 11.0% or less, particularly preferably 10.0% or less, and most preferably 9.0% or less.

[0036] (WO ３ ) Glass 10 is WO ３ It is not necessary to include it, but it is preferable to include it from the viewpoint of improving the refractive index. Glass 10 is expressed in mol% based on oxide, WO ３ The content is 0.0% to 7.5%. In glass 10, WO ３ The refractive index can be increased by including WO ３ The content of is preferably more than 0.0%, more preferably 0.10% or more, even more preferably 0.20% or more, even more preferably 0.30% or more, particularly preferably 0.40% or more, and most preferably 0.50% or more. Also, in glass 10, WO ３If a large amount of WO is included, the melting properties of the raw material will deteriorate, and the transmittance may decrease significantly. Therefore, WO ３ The content of is more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 4.0% or less, especially preferably 3.0% or less, particularly preferably 2.5% or less, and most preferably 2.0% or less.

[0037] [Bi ２ O ３ ] [Nb ２ O ５ ] Article TiO ２ ] 〔WO ３ [Bi] contributes to improving the refractive index, while excess increases the risk of decreased transmittance and crystallization / blackening. Glass 10 is expressed in mole percent based on oxide, [Bi ２ O ３ ] is 29.0% to 34.0%, [Nb ２ O ５ ] is 5.5% to 9.0%, [TiO ２ ] is 0.0% to 11.0%, and [WO ３ If the combination of ] is between 0.0% and 4.5%, then nd ≥ 2.07 and τ ４５０ This combination is particularly preferable because it makes it easier to achieve ≥90% and suppresses increases in devitrification temperature and density. These combinations also contribute to ensuring that parameter B is within an appropriate range.

[0038] (RO) RO is the total content of MgO, CaO, SrO, and BaO. By including RO, the mellowness, refractive index, and Young's modulus of the raw material can be adjusted, but it may reduce the transmittance and is therefore an optional component. Glass 10 has an RO content of 0% to 7.0% in molar percentage based on oxides. By including RO in glass 10, the refractive index can be increased. In glass 10, the RO content is more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is acceptable to include it as an unavoidable impurity. If RO is included, the RO content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0039] (MgO) Glass 10 has an MgO content of 0% to 7.0% in molar percentage based on oxides. In glass 10, the Young's modulus can be increased by including MgO, but the transmittance may decrease, so it is an optional component. In glass 10, the MgO content is more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is acceptable to include it as an unavoidable impurity. If MgO is included, the MgO content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0040] (CaO) Glass 10 has a CaO content of 0% to 7.0% in molar percentage based on oxides. In glass 10, the Young's modulus can be increased by including CaO, but the transmittance may decrease, so it is an optional component. In glass 10, the CaO content is more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is acceptable for it to be included as an unavoidable impurity. If CaO is included, the CaO content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0041] (SrO) Glass 10 has a SrO content of 0% to 7.0% in molar percentage based on oxides. In glass 10, the refractive index can be increased by including SrO, but the transmittance may decrease, so it is an optional component. In glass 10, the SrO content is more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is acceptable to include it as an unavoidable impurity. If SrO is included, the SrO content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0042] (BaO) Glass 10 has a BaO content of 0% to 7.0% in molar percentage based on oxides. In glass 10, the refractive index can be increased by including BaO, but the transmittance may decrease, so it is an optional component. In glass 10, the BaO content is more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, especially preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is acceptable to include it as an unavoidable impurity. If BaO is included, the BaO content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0043] (R' ２ O) R' ２ O is Li ２ O, Na ２ O, K ２ This is the total O content. Glass 10 is expressed in mole percent based on oxide, R' ２ The O content is 0% to 10.0%. In glass 10, R' ２ The inclusion of O improves the melting properties of the raw material and can increase Young's modulus, but if present in large quantities, it may lower the refractive index. In glass 10, R' ２ The O content is more preferably 0.50% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, particularly preferably 2.0% or more, and most preferably 2.5% or more. In glass 10, R' ２ The O content is more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, especially preferably 5.5% or less, particularly preferably 5.0% or less, and most preferably 4.5% or less.

[0044] Glass 10 is TiO ２ If it contains, express in mole percent based on oxide, [Li ２ Contains 1.0% to 4.5% of [O] and Li relative to the total amount of alkali metals ２ Ratio of O content ([Li ２ O] / [R'２ When O) is set to 0.25 to 1.0 (preferably 0.50 or higher), the Young's modulus and stiffness modulus increase simultaneously while suppressing phase splitting, resulting in a fracture toughness value K Ｃ This is particularly preferable because it can improve Vickers hardness and Knoop hardness without causing a decrease in [TiO]. Furthermore, the glass 10 has the above content expressed in molar percentage on an oxide basis as [TiO] ２ When ] is combined with 0.5% to 11.0%, the refractive index n ｄ and transmittance τ ４５０ It is particularly preferable that both be within an appropriate range.

[0045] (Li ２ O) Glass 10 is TiO on an oxide basis. ２ and Li ２ It contains at least one of O. Glass 10 is Li ２ Although it is not necessary to contain O, it is preferable to include it from the viewpoint of improving Young's modulus. Glass 10 is expressed in mol% based on oxide, Li ２ The O content is 0% to 10.0%. In glass 10, Li ２ The Young's modulus can be increased by including O. In glass 10, Li ２ The O content is more preferably 0.50% or more, even more preferably 0.75% or more, even more preferably 1.0% or more, particularly preferably 1.2% or more, and most preferably 1.5% or more. Also, in glass 10, Li ２ If a large amount of oxygen is present, crystallization is more likely to occur, which may lead to an increase in the devitrification temperature and a decrease in the refractive index. Therefore, Li ２ The O content is more preferably 9.0% or less, even more preferably 8.0% or less, even more preferably 7.0% or less, especially preferably 6.0% or less, particularly preferably 5.0% or less, and most preferably 4.5% or less.

[0046] (Na ２ O) Glass 10 is expressed in mol% based on oxide, Na ２ The O content is 0% to 10.0%. In glass 10, Na ２The inclusion of O improves the melting properties of the raw material and can increase the Young's modulus, but if present in large quantities, it may lead to a decrease in refractive index and phase separation (phase splitting), resulting in a decrease in transmittance, so it is an optional component. In glass 10, Na ２ The O content is more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, especially preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0% (not present). Note that 0% (not present) means that it is acceptable for it to be present as an unavoidable impurity. Na ２ If it contains O, Na ２ The O content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0047] (K ２ O) Glass 10 is expressed in mole percent based on oxide, K ２ The O content is 0% to 10.0%. In glass 10, K ２ The inclusion of O improves the melting properties of the raw material, but if included in large quantities, it may reduce the refractive index and Young's modulus, so it is an optional component. In glass 10, K ２ The O content is more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, especially preferably 1.0% or less, particularly preferably 0.50% or less, and most preferably 0% (not present). Note that 0% (not present) means that its presence as an unavoidable impurity is acceptable. K ２ If O is present, K ２ The O content may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0048] Glass 10 is used to improve the refractive index and Young's modulus. ２ O ３ La ２ O ３ Ga ２ O ３ , Gd ２ O ３ Yb２ O ３ and Ta ２ O ５ These components may be included. If these components are included in large quantities, there is a risk of the raw material's melting temperature rising or crystallization occurring during melting and molding; therefore, they are optional components. In glass 10, the total content of the above components, expressed in mole percent based on oxides, is more preferably 0.90% or less, even more preferably 0.80% or less, even more preferably 0.70% or less, particularly preferably 0.60% or less, especially preferably 0.50% or less, and most preferably 0% (not included). Note that 0% (not included) means that it is permissible for them to be included as unavoidable impurities. If the above components are included, the total content of these components, expressed in mole percent based on oxides, may be 0.10% or more, 0.20% or more, 0.30% or more, or 0.40% or more.

[0049] ([Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ Glass 10 is expressed in molar percentage based on oxide ([Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ ]) is 80% or less. ([Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ When the ratio of ([Bi) is 80% or less, the Young's modulus increases and the glass transition temperature rises, resulting in improved strength and thermal stability. Furthermore, the coefficient of linear expansion also decreases, making the glass less prone to cracking during molding and cooling, as well as during reheat press molding (molding while heating and pressing). ２ O ３ ] + [B ２ O ３] + [P ２ O ５ ] + [TeO ２ ]) is more preferably 78% or less, even more preferably 76% or less, even more preferably 74% or less, particularly preferably 72% or less, and most preferably 70% or less. ([Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ If the amount is low, the chemical durability such as acid resistance, alkali resistance and water resistance may decrease, so 50% or more is preferred, 53% or more is more preferred, 55% or more is even more preferred, 57% or more is particularly preferred, and 60% or more is most preferred.

[0050] Glass 10 is expressed in mole percent based on oxide, [Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ If ] is between 67.0% and 77.0%, then the transmittance τ ４５０ ≥90%, refractive index n ｄ ≥2.07, Young's modulus ≥80 GPa, coefficient of linear expansion CTE ≤10⁵ × 10⁵ －７ It is preferable because it is easy to satisfy both / °C simultaneously. In particular, the glass 10 is expressed in mole percent on an oxide basis as [Bi ２ O ３ ] + [B ２ O ３ ] + [P ２ O ５ ] + [TeO ２ Setting ] to 69.5% to 77.0% is preferable because it allows for both an increase in parameter B (equation (2)) and securing of parameter C (equation (3)), thereby achieving a high refractive index while suppressing transmission loss and specific gravity increase in the blue region.

[0051] ([Bi ２ O ３ ] + [Nb ２ O ５ Glass 10 is expressed in molar percentage based on oxide ([Bi ２ O ３] + [Nb ２ O ５ It is preferable that ]) is 45% or less. ([Bi ２ O ３ ] + [Nb ２ O ５ By having ]) at 45% or less, crystallization can be suppressed and the devitrification temperature can be lowered. In glass 10, ([Bi ２ O ３ ] + [Nb ２ O ５ ([Bi ２ O ３ ] + [Nb ２ O ５ If the amount of ) is small, the refractive index decreases, so 30% or more is preferred, 31% or more is more preferred, 32% or more is even more preferred, 33% or more is even more preferred, 34% or more is particularly preferred, and 35% or more is most preferred.

[0052] Glass 10 is expressed in mol% based on oxide, ([Bi ２ O ３ ] + [Nb ２ O ５ ]) 30.0% to 38.0%, ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ ]) to 1.00 to 1.30, ([Bi ２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ A combination in which the ratio of ) is 1.15 or less is particularly preferred. This suppresses the occurrence of blackening and devitrification, while maintaining the refractive index nd and transmittance τ.４５０ This enables simultaneous optimization of both the modulus and Young's modulus.

[0053] ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ Glass 10 is expressed in molar percentage based on oxide ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ It is preferable that ]) is 0.90 or higher. ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ The refractive index can be increased if the ratio is 0.90 or higher. ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ ([Bi ２ O ３ ] + [Nb２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ ]) is preferably 1.50 or less. ([Bi ２ O ３ ] + [Nb ２ O ５ ] + [TiO ２ ] + [WO ３ ]) / ([B ２ O ３ ] + [P ２ O ５ ]) is more preferably 1.45 or less, even more preferably 1.40 or less, even more preferably 1.35 or less, even more preferably 1.33 or less, particularly preferably 1.31 or less, and most preferably 1.30 or less.

[0054] ([Bi ２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ Glass 10 is expressed in molar percentage based on oxide ([Bi ２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ It is preferable that ]) is 1.40 or less. ([Bi ２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ The specific gravity increase is suppressed by keeping the ratio of ]) below 1.40, and the Knoop hardness and fracture toughness value K described later are also suppressed. Ｃ It can increase ([Bi２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ ([Bi ２ O ３ ] + [Nb ２ O ５ ]) / ([B ２ O ３ ] + [P ２ O ５ ] + [TiO ２ The lower limit of ) is not particularly limited, but from the viewpoint of increasing the refractive index, 0.70 or higher is preferred.

[0055] (Li ２ O / R' ２ O) Glass 10 contains the total amount of alkali metals [R'] in molar percentage based on oxides. ２ [Li] for O ２ O] Ratio Li ２ O / R' ２ It is preferable that O is greater than 0. ２ O / R' ２ By having O greater than 0, it is possible to increase Young's modulus while suppressing phase separation. In glass 10, Li ２ O / R' ２ O is more preferably 0.10 or higher, even more preferably 0.25 or higher, even more preferably 0.50 or higher, especially preferably 0.60 or higher, particularly preferably 0.70 or higher, and most preferably 0.80 or higher.

[0056] (Fe, Cr, Ni content) The total content of Fe, Cr, and Ni in glass 10 is preferably 5.0 ppm or less by mass ratio, more preferably 4.5 ppm or less, even more preferably 4.0 ppm or less, even more preferably 3.5 ppm or less, particularly preferably 3.0 ppm or less, and most preferably 2.5 ppm or less, relative to the total content of glass 10. The lower limit is not particularly limited, but the lower limit of the total content of Fe, Cr, and Ni is, for example, 1.0 ppm or more. Here, Fe, Cr, and Ni refer not only to the elemental metals of Fe, Cr, and Ni contained in glass 10, but may also include elemental metals of Fe, Cr, and Ni and compounds. That is, the total content of Fe, Cr, and Ni can be said to include the content of elemental metals of Fe, Cr, and Ni and the content of ions of Fe, Cr, and Ni in compounds. By keeping the total content of the coloring transition metals Fe, Cr, and Ni within this range, it is possible to suppress the decrease in the transmittance of the glass 10 to visible light and to make the glass 10 highly transmittant to visible light. The total content of Fe, Cr, and Ni can be measured by ICP mass spectrometry. For example, the Agilent 8800 manufactured by Agilent Technologies can be used as a measuring instrument.

[0057] (Content of Pt and Au) The Pt content of glass 10 is preferably 1.5 ppm or less by mass ratio of the total glass 10, more preferably 1.2 ppm or less, even more preferably 1.0 ppm or less, even more preferably 0.70 ppm or less, particularly preferably 0.50 ppm or less, and most preferably 0.40 ppm or less. There is no particular lower limit, but the lower limit of the Pt content is, for example, 0.10 ppm or more. The Au content of glass 10 is preferably 50.0 ppm or less by mass ratio of the total glass 10, more preferably 40.0 ppm or less, even more preferably 35.0 ppm or less, even more preferably 30.0 ppm or less, particularly preferably 25.0 ppm or less, and most preferably 20.0 ppm or less. By having such low Pt and Au content, the transmittance can be improved. Here, Pt and Au do not refer only to the elemental metals Pt and Au contained in the glass 10, but may include both elemental metals and compounds of Pt and Au. In other words, the total content of Pt and Au can be said to include the content of elemental metals Pt and Au and the content of Pt and Au ions in the compounds. The content of Pt and Au can be measured by ICP mass spectrometry. For example, the Agilent 8800 manufactured by Agilent Technologies can be used as a measuring instrument.

[0058] (Properties of Glass) The properties of glass 10 are described below.

[0059] (transmittance τ ４４０ ) Transmittance τ of glass 10 ４４０ The transmittance is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 81% or more, even more preferably 82% or more, even more preferably 83% or more, even more preferably 84% or more, even more preferably 85% or more, even more preferably 86% or more, even more preferably 87% or more, even more preferably 88% or more, even more preferably 89% or more, especially preferably 90% or more, and most preferably 91% or more.４４０ By falling within this range, the optical properties are appropriately improved, allowing for proper transmission of visible light. ４４０ This represents the internal transmittance for light with a wavelength of 440 nm when converted to a thickness of 10 mm.

[0060] Internal transmittance is the transmittance that passes through the interior of the glass 10. Internal transmittance can be determined from the measured values ​​of two types of external transmittances with different plate thicknesses and the following formula (A). External transmittance refers to transmittance including surface reflection loss. In formula (A), τ is the internal transmittance of the glass when converted to a thickness of 10 mm, T1 and T2 are the external transmittances, and Δd is the difference in thickness of the sample. External transmittance can be measured using a spectrophotometer (JASCO Corporation: V-770) and an integrating sphere unit (JASCO Corporation: ISN-923) on samples with plate thicknesses of 7.0 mm and 1.2 mm that have been mirror-polished on both sides.

[0061]

[0062] (transmittance τ ４５０ ) Transmittance τ of glass 10 ４５０ The transmittance τ is 85% or more, more preferably 88% or more, even more preferably 89% or more, even more preferably 90% or more, even more preferably 91% or more, even more preferably 92% or more, especially preferably 93% or more, and most preferably 94% or more. ４５０ By falling within this range, the optical properties are appropriately improved, allowing for proper transmission of visible light. ４５０ This represents the internal transmittance for light with a wavelength of 450 nm when converted to a thickness of 10 mm.

[0063] (transmittance τ ４６０ ) Transmittance τ of glass 10 ４６０ The transmittance τ is preferably 90% or more, more preferably 91% or more, even more preferably 92% or more, even more preferably 93% or more, even more preferably 94% or more, even more preferably 95% or more, particularly preferably 96% or more, and most preferably 97% or more. ４６０ By falling within this range, the optical properties are appropriately improved, allowing for proper transmission of visible light. ４６０This represents the internal transmittance for light with a wavelength of 460 nm when converted to a thickness of 10 mm.

[0064] (Refractive index n ｄ ) Refractive index n of glass 10 ｄ The refractive index n is 2.050 or higher, more preferably 2.060 or higher, even more preferably 2.065 or higher, even more preferably 2.070 or higher, even more preferably 2.075 or higher, even more preferably 2.078 or higher, even more preferably 2.080 or higher, even more preferably 2.082 or higher, even more preferably 2.085 or higher, especially preferably 2.087 or higher, and most preferably 2.090 or higher. ｄ Because it falls within this range, when used as a light guide plate, the total reflection angle of incident light is broadened, and the field of view can be expanded. Note that the refractive index n ｄ This refers to the refractive index of helium at the d-line (wavelength 587.6 nm). ｄ This can be measured using the V-block method.

[0065] (Abbe number v) ｄ ) Abbe number v of glass 10 ｄ Abbe number v is preferably 17.5 or higher, more preferably 17.7 or higher, even more preferably 17.9 or higher, even more preferably 18.0 or higher, even more preferably 18.2 or higher, even more preferably 18.5 or higher, particularly preferably 18.8 or higher, and most preferably 19.0 or higher. ｄ This range reduces the dispersion of refractive index for each wavelength, allowing a high refractive index to be maintained even when the wavelength used changes, thereby expanding the field of view. Note that the Abbe number v ｄ This value represents a property related to variance. Abbe number v ｄ It can be measured using the V-block method and can be determined by the following formula (B): v ｄ = (n ｄ -1) / (n F -n C ) ... (B)

[0066] Refractive index n F This refers to the refractive index of hydrogen in the F line (wavelength 486.1 nm), where n is the refractive index. CThis refers to the refractive index of hydrogen in the C line (wavelength 656.3 nm). F , n C This can be measured using the V-block method.

[0067] (Solarization Resistance) The glass 10 preferably has a solarization resistance ΔT of 0.80% or less in the ultraviolet irradiation test, more preferably 0.75% or less, even more preferably 0.70% or less, even more preferably 0.65% or less, particularly preferably 0.60% or less, and most preferably 0.55% or less. When the solarization resistance ΔT is within this range, the decrease in transmittance can be suppressed even when irradiated with ultraviolet light, and the decrease in transmittance to visible light can be suppressed. Here, the solarization resistance in the ultraviolet irradiation test is determined by the following formula (C): ΔT (%) = {(T ４ -T ３ ) / T ４}・100...(C)

[0068] Transmittance T in equation (C) ３ This involves exposing the surface of a 1.2 mm thick glass 10 to ultraviolet light with a wavelength of 365 nm at a rate of 15,000 mJ / cm². ２ This refers to the external transmittance of 440 nm wavelength light through the glass 10 after irradiation. More specifically, the UV irradiance on the glass surface is adjusted using an ultraviolet integrated light meter (UIT-250, manufactured by Ushio Inc.), and 365 nm wavelength ultraviolet light is irradiated onto the surface of the glass 10 from a low-pressure mercury lamp (H400-P, manufactured by Harrison Toshiba Lighting Corporation) at a rate of 15,000 mJ / cm². ２ The glass 10 is irradiated with ultraviolet light in this manner. Using a spectrophotometer (JASCO Corporation: V-770) and an integrating sphere unit (JASCO Corporation: ISN-923), the external transmittance of light with a wavelength of 440 nm is measured, and this value is called the transmittance T. ３ Let's assume that the transmittance T in equation (1) is calculated as follows. ４This is the transmittance of glass 10 at a wavelength of 440 nm before ultraviolet irradiation. That is, even for glass 10 before ultraviolet irradiation as described above, the external transmittance of light at a wavelength of 440 nm is measured in advance using a spectrophotometer (JASCO Corporation: V-770) and an integrating sphere unit (JASCO Corporation: ISN-923), and this value is used as transmittance T. ４ Let's assume that.

[0069] (Specific Gravity Sg) The specific gravity Sg of glass 10 is preferably 6.50 or less, more preferably 6.40 or less, even more preferably 6.30 or less, even more preferably 6.20 or less, particularly preferably 6.10 or less, and most preferably 6.00 or less. There is no particular lower limit to the specific gravity Sg, but for example it is 5.50 or more. Such a low specific gravity makes the glass 10 easy to handle. The specific gravity Sg can be measured by the Archimedes method.

[0070] (Young's Modulus) The Young's modulus of glass 10 is preferably 75 GPa or higher, more preferably 76 GPa or higher, even more preferably 77 GPa or higher, even more preferably 78 GPa or higher, even more preferably 79 GPa or higher, even more preferably 80 GPa or higher, even more preferably 81 GPa or higher, even more preferably 82 GPa or higher, even more preferably 83 GPa or higher, especially preferably 84 GPa or higher, and most preferably 85 GPa or higher. Such a high Young's modulus effectively suppresses cracking of glass 10. The Young's modulus can be measured by the ultrasonic pulse method based on JIS R1602:1995 "Test Method for Elastic Modulus of Fine Ceramics".

[0071] (Rigidity) The rigidity of the glass 10 is preferably 30.0 GPa or higher, more preferably 30.5 GPa or higher, even more preferably 31.0 GPa or higher, even more preferably 31.5 GPa or higher, even more preferably 32.0 GPa or higher, even more preferably 32.5 GPa or higher, particularly preferably 33.0 GPa or higher, and most preferably 33.5 GPa or higher. Such a high rigidity allows for appropriate suppression of cracking of the glass 10. The rigidity can be measured by the ultrasonic pulse method based on JIS R1602:1995 "Test method for the elastic modulus of fine ceramics".

[0072] (Knoop hardness) The Knoop hardness of glass 10 is preferably 370 HK or higher, more preferably 380 HK or higher, even more preferably 390 HK or higher, even more preferably 400 HK or higher, particularly preferably 410 HK or higher, and most preferably 420 HK or higher. A Knoop hardness within this range improves the wear resistance of glass 10. The Knoop hardness can be evaluated using the Future Tech fully automated micro / Vickers hardness test system (ARS-F). In this case, the measurement conditions may be a load of 50 gf and a pressurization time of 15 seconds.

[0073] (Vickers hardness) The Vickers hardness of glass 10 is preferably 465 HV or higher, more preferably 470 HV or higher, even more preferably 475 HV or higher, even more preferably 480 HV or higher, particularly preferably 485 HV or higher, and most preferably 490 HV or higher. A Vickers hardness within this range improves the wear resistance of glass 10. The Vickers hardness can be evaluated using a microhardness tester (MVK-H100) manufactured by Akashi Seisakusho Co., Ltd. The measurement conditions in this case may be a load of 25 gf and a pressurization time of 15 seconds. The same conditions may be used when evaluating fracture toughness using the indentation fracture method (IF) described below.

[0074] (Fracture toughness value K) Ｃ ) Fracture toughness value K of glass 10 Ｃ This is 0.35 MPa·m ０．５ The above is preferable, and 0.36 MPa·m ０．５ The above is more preferable, 0.37 MPa·m ０．５ The above is even more preferable, 0.38 MPa·m ０．５ The above is even more preferable, 0.39 MPa·m ０．５ The above is particularly preferred, and is 0.40 MPa·m ０．５ The above is the most preferable. Fracture toughness value K Ｃ By being within this range, cracking of the glass 10 can be suppressed. Note that the fracture toughness value K Ｃ For example, it can be measured using the IF method compliant with JIS R1607.

[0075] (Brittleness) The Brittleness of glass 10 is 13.0 μm ０．５ The following is preferred: 12.8 μm ０．５ The following is more preferable: 12.5 μm ０．５ The following is even more preferable: 12.3 μm ０．５ The following is particularly preferred: 12.0 μm ０．５ The following is most preferable. When Brittleness falls within this range, cracking of the glass 10 can be suppressed. Brittleness is a value calculated by the following formula (D). In formula (D), H is the Vickers hardness, and K is... Ｃ This is the fracture toughness value K of glass 10, determined by the IF method. Ｃ That is the case.

[0076] Brittleness=H / K Ｃ ... (D)

[0077] (Coefficient of linear expansion CTE) The coefficient of linear expansion CTE of glass 10 is 105 × 10 －７ Preferably below / ℃, 103 × 10 －７ / ℃ or lower is more preferable, 100 × 10 －７ A temperature of 1 / °C or lower is even more preferable, and 97 × 10 －７ More preferably below / ℃, 95 × 10 －７ More preferably below / ℃, 93 × 10 －７ A temperature of 1 / °C or lower is particularly preferred, and 90 × 10 －７ A value of less than / °C is most preferable. Having the coefficient of linear expansion (CTE) within this range suppresses cracking of the glass 10 during molding and slow cooling. The coefficient of linear expansion is the average coefficient of linear expansion in the range of 100°C to 300°C, and is measured in accordance with the DIN-51045-1 standard for measuring linear expansion. For example, a thermal expander (DIL 402 Expedis Supreme) manufactured by NETZSCH may be used as the measuring device, and measurements may be taken in the range of 30°C to 400°C, with the average coefficient of linear expansion in the range of 100°C to 300°C being used as the coefficient of linear expansion.

[0078] (Glass transition temperature Tg) The glass transition temperature Tg of glass 10 is preferably 420°C or higher, more preferably 425°C or higher, even more preferably 430°C or higher, even more preferably 435°C or higher, and particularly preferably 440°C or higher. Furthermore, the glass transition temperature Tg of glass 10 is preferably 500°C or lower, more preferably 490°C or lower, even more preferably 480°C or lower, particularly preferably 475°C or lower, and most preferably 470°C or lower. This allows for a lower heating temperature during reheat press molding (molding while heating and pressing). The glass transition temperature can be measured according to the method specified in JIS R3103-3:2001 "Viscosity and viscosity fixed points of glass - Part 3: Method for measuring transition temperature by thermal expansion method".

[0079] (Fracture Point At) The fracture point At of the glass 10 is preferably 450°C or higher, more preferably 455°C or higher, even more preferably 460°C or higher, even more preferably 465°C or higher, particularly preferably 470°C or higher, and most preferably 475°C or higher. Furthermore, the fracture point At of the glass 10 is preferably 540°C or lower, more preferably 530°C or lower, even more preferably 520°C or lower, particularly preferably 510°C or lower, and most preferably 500°C or lower. This allows for a lower heating temperature during reheat press molding. The fracture point At is the point in the thermal expansion curve obtained when measuring the transition temperature by the thermal expansion method, where the slope of the thermal expansion curve becomes zero in the temperature range above the glass transition point.

[0080] The difference between the bending point At of the glass 10 and the glass transition point Tg of the glass 10 (bending point At - glass transition point Tg) is preferably 23°C or higher, more preferably 25°C or higher, even more preferably 27°C or higher, and most preferably 30°C or higher. Furthermore, the difference between the bending point At of the glass 10 and the glass transition point Tg of the glass 10 (bending point At - glass transition point Tg) is preferably 50°C or lower, more preferably 47°C or lower, even more preferably 45°C or lower, even more preferably 43°C or lower, particularly preferably 40°C or lower, and most preferably 37°C or lower. This results in excellent formability during reheat press molding.

[0081] (Basicity) The basicity of glass 10 is preferably 0.430 or higher, more preferably 0.435 or higher, even more preferably 0.440 or higher, even more preferably 0.443 or higher, particularly preferably 0.445 or higher, and most preferably 0.447 or higher. A basicity of 0.430 or higher for glass 10 can increase the Young's modulus. If the basicity of glass 10 is too high, the transmittance may decrease, so it is preferably 0.470 or lower, more preferably 0.465 or lower, even more preferably 0.460 or lower, particularly preferably 0.455 or lower, and most preferably 0.452 or lower.

[0082] The basicity of glass 10 indicates the electron-donating nature of oxygen atoms in the glass and is a value that can be determined by the following formula (E) (Λ ｃａｌ ) refers to.

[0083]

[0084] In formula (E), Z ｉ is the valence of the cation i in the glass, and r ｉ γ is the ratio of cation i to the total oxide ions in the glass, ｉ γ is a basic moderating parameter that indicates the degree to which cation i reduces the electron-donating ability of oxide ions. ｉ γ has a relationship with Pauling's electronegativity χ, which can be expressed by the following formula (F): ｉ = 1.36(χ ｉ -0.26) (F)

[0085] r ｉ This is the ratio of cation i to the total oxide ions in the glass, and is a value uniquely calculated from the glass composition. The total oxide ions in the glass are the sum of (number of oxygen atoms in one molecule of each component × mole %) of each component. The basicity is calculated optical basicity using an empirical formula, as proposed by J. A. Duffy and M. D. Ingram, J. Non-Cryst. Solids 21 (1976) 373.

[0086] (βOH) The βOH content of glass 10 is 0.05 mm －１The above is preferable, and 0.10 mm －１ The above is more preferable, and 0.15 mm or more. －１ More preferably, 0.20 mm －１ The above is even more preferable, 0.25 mm －１ The above is particularly preferred, 0.30 mm －１ The above is the most preferable. The βOH content of glass 10 is 0.05 mm －１ This allows for increased transmittance. The βOH content of glass 10 is 1.0 mm －１ The following is preferable: 0.80 mm －１ The following is more preferable: 0.70 mm －１ The following is even more preferable: 0.60 mm －１ The following is even more preferable: 0.50 mm －１ The following is particularly preferred: 0.45 mm －１ The following is most preferable: The βOH content of glass 10 is 1.0 mm －１ The following conditions improve chemical durability, such as acid resistance, alkali resistance, and water resistance. βOH is an indicator of the water content in the glass; a larger βOH value means a higher water content in the glass. The βOH of glass 10 can be set to the above range, for example, by adjusting the amount of water used in the manufacture of glass 10. The βOH of glass 10 is calculated using the following formula (G).

[0087] βOH=(1 / D)log10(τ1 / τ2) ...(G)

[0088] In formula (G), βOH is the value of βOH in glass 10 (mm －１ ) refers to the thickness of the glass 10 (mm), τ1 is the reference wavenumber 3845 (cm －１ τ2 refers to the transmittance (%) of glass 10 at the reference wavenumber 3298 (cm²). －１ This refers to the minimum transmittance (%) of glass 10 in ). A Fourier transform infrared spectrometer (FT-IR) is used to measure the transmittances τ1 and τ2.

[0089] (Glass Form) The glass 10 according to this embodiment is preferably optical glass, and preferably a glass plate with a thickness of 0.01 mm or more and 3.0 mm or less. If the thickness is 0.01 mm or more, breakage during handling and processing of the glass 10 can be suppressed. Also, deflection due to the weight of the glass 10 can be suppressed. This thickness is more preferably 0.1 mm or more, even more preferably 0.2 mm or more, and even more preferably 0.3 mm or more. On the other hand, if the thickness is 3.0 mm or less, the optical element using the glass 10 can be made lighter. This thickness is more preferably 2.0 mm or less, even more preferably 1.5 mm or less, even more preferably 1.0 mm or less, and particularly preferably 0.8 mm or less.

[0090] In the case where the glass 10 in this embodiment is a glass plate, the area of ​​the main surface is 8 cm². ２ The above is preferable. ２ If the area is larger than this, a large number of optical elements can be arranged, improving productivity. This area is more preferably 30 cm². ２ The above, and more preferably 170 cm ２ The above, and more preferably 300 cm ２ The above, and more preferably 700 cm ２ The above is true, and is particularly preferably 1000 cm ２ The above is the most preferred, and most preferably 1200 cm ２ That's all. On the other hand, the area is 6500 cm². ２ The following conditions make handling the glass plate easier and reduce breakage during handling and processing. This area is more preferably 4500 cm². ２ The following, and more preferably 4000 cm ２ The following, and more preferably 3000 cm ２ The following, and particularly preferably 2000 cm ２ The following applies:

[0091] In the case where the glass 10 according to this embodiment is a glass plate, the main surface is 25 cm ２The LTV (Local Thickness Variation) in this context is preferably 2 μm or less. Having a flatness within this range allows for the formation of nanostructures of a desired shape on the main surface using imprint technology, etc., and enables the acquisition of desired light-guiding characteristics. In particular, it prevents ghosting and distortion caused by differences in optical path length in the light guide. This LTV is more preferably 1.5 μm or less, even more preferably 1.0 μm or less, and particularly preferably 0.5 μm or less.

[0092] When the glass 10 according to this embodiment is a circular glass plate with a diameter of 8 inches, the curvature is preferably 50 μm or less. If the curvature of this glass 10 is 50 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The curvature of this glass 10 is more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0093] Furthermore, when the glass 10 according to this embodiment is a circular glass plate with a diameter of 6 inches, the curvature is preferably 30 μm or less. If the curvature of this glass 10 is 30 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The curvature of this glass 10 is more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0094] Furthermore, when the glass 10 according to this embodiment is a square glass plate with sides of 6 inches, the warp is preferably 100 μm or less. If the warp of this glass 10 is 100 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The warp of this glass 10 is more preferably 70 μm or less, even more preferably 50 μm or less, even more preferably 35 μm or less, and particularly preferably 20 μm or less.

[0095] Figure 2 is a cross-sectional view of the glass according to this embodiment when it is a glass plate. "Warping" is the difference C between the maximum value B and the minimum value A of the vertical distance between the reference line G1D of the glass plate G1 and the center line G1C of the glass plate G1, in any cross section that passes through the center of the main surface G1F of the glass plate G1 and is perpendicular to the main surface G1F of the glass plate G1.

[0096] The intersection line between the aforementioned orthogonal cross-sections and the main surface G1F of the glass plate G1 is defined as the bottom line G1A. The intersection line between the aforementioned orthogonal cross-sections and another main surface G1G of the glass plate G1 is defined as the top line G1B. Here, the center line G1C is the line connecting the centers of the glass plate G1 in the thickness direction. The center line G1C is calculated by finding the midpoint between the bottom line G1A and the top line G1B with respect to the laser irradiation direction, which will be described later.

[0097] The reference line G1D is determined as follows: First, the base line G1A is calculated using a measurement method that cancels out the effect of the self-weight. From this base line G1A, a straight line is determined by the least squares method. The determined straight line is the reference line G1D. A known method is used as the measurement method that cancels out the effect of the self-weight.

[0098] For example, the main surface G1F of a glass plate G1 is supported at three points, and a laser is shone onto the glass plate G1 using a laser displacement meter to measure the height of the main surface G1F and the other main surfaces G1G of the glass plate G1 from an arbitrary reference plane.

[0099] Next, the glass plate G1 is inverted, and three points on the other main surface G1G opposite to the three points supporting one main surface G1F are supported. The heights of the main surface G1F and the other main surface G1G of the glass plate G1 are then measured from an arbitrary reference plane. The effect of self-weight is canceled out by calculating the average of the heights of each measurement point before and after inversion. For example, before inversion, the height of the main surface G1F is measured as described above. After inverting the glass plate G1, the height of the other main surface G1G is measured at the positions corresponding to the measurement points of the main surface G1F. Similarly, before inversion, the height of the other main surface G1G is measured. After inverting the glass plate G1, the height of the main surface G1F is measured at the positions corresponding to the measurement points of the other main surface G1G. Warpage is measured, for example, by a laser displacement meter.

[0100] Furthermore, in the glass 10 according to this embodiment, the surface roughness Ra of the main surface is preferably 2 nm or less. Having Ra within this range allows for the formation of nanostructures of a desired shape on the main surface using imprint technology or the like, and enables the acquisition of desired light-guiding properties. In particular, diffuse reflection at the interface is suppressed in the light guide, preventing ghosting and distortion. This Ra is more preferably 1.7 nm or less, even more preferably 1.4 nm or less, even more preferably 1.2 nm or less, and particularly preferably 1 nm or less. Here, the surface roughness Ra is the arithmetic mean roughness as defined in JIS B0601 (2001). In this specification, it is the value measured using an atomic force microscope (AFM) over a 10 μm × 10 μm area.

[0101] (Method for manufacturing glass) The method for manufacturing the glass 10 according to this embodiment is not particularly limited, and existing methods for manufacturing flat glass such as the float method, fusion method, and roll-out method can be used. In addition to these, known methods such as slicing a cast glass ingot to cut out a glass plate can also be used. However, in order to suppress deterioration of transmittance due to the inclusion of impurities, it is preferable that the material of the container (crucible) in which the raw materials are placed when melting the raw materials be at least one of Pt, Au, and Au alloy.

[0102] Furthermore, in the glass 10 of this embodiment, it is preferable to perform an operation to increase the water content in the molten glass during the melting process in which the glass raw material is heated and melted in a melting container to obtain molten glass. The operation to increase the water content in the glass is not limited, but for example, it is possible to use a water-containing raw material, add water vapor to the melting atmosphere, or bubble a gas containing water vapor into the molten material. The operation to increase the water content is not essential, but it can be done for the purpose of improving transmittance, clarity, etc. Also, in the glass 10 of this embodiment, Li ２ O and Na ２ Materials containing alkali metal oxides of oxygen can be chemically strengthened by substituting Li ions with Na ions or K ions, or Na ions with K ions. In other words, chemical strengthening treatment can improve the strength of optical glass.

[0103] (Effects) As described above, the glass 10 according to the first aspect of this disclosure has an internal transmittance of 85% or more for light with a wavelength of 450 nm when converted to a thickness of 10 mm, and the refractive index of the d line n ｄ The value is 2.050 or higher, and TiO is the oxide standard. ２ and Li ２ It contains at least one of O, and in terms of molar percentage based on oxides, Bi ２ O ３ :20.0%~40.0% SiO ２ :0%~5.0% Al ２ O ３ : 0% to 5.0% B ２ O ３ :15.0%~35.0% P ２ O ５ : More than 0% to 20.0% Nb ２ O ５ :0%~12.0% TeO ２ :1.0%~30.0% ZnO:0%~20.0% ZrO ２ :0%~10.0% TiO ２ :0%~20.0% WO ３ :0%~7.5% RO:0%~7.0% R' ２ O: Contains 0% to 10.0%, and parameter A, represented by formula (1), is 0.95 or higher. According to this disclosure, having the above characteristics makes it possible to suppress cracking while improving optical properties. That is, it is possible to suppress cracking while appropriately transmitting and refracting visible light.

[0104] The glass 10 according to the second aspect of this disclosure is the glass 10 according to the first aspect, and is expressed in mole percentage on an oxide basis, Bi ２ O ３ :25.0%~35.0% SiO ２ :0%~2.0% Al ２ O ３ : 0% to 2.0% B ２ O ３ :20.0%~32.0% P ２ O ５ :5.0%~15.0% Nb ２ O ５:4.0%~10.0% TeO ２ :1.5%~20.0% ZnO:3.0%~15.0% ZrO ２ :1.0%~5.0% TiO ２ :0%~15.0% WO ３ :0%~5.0% RO:0%~5.0% R' ２ O: Contains 0% to 7.0%. According to this disclosure, cracking can be suppressed while improving optical properties. That is, cracking can be suppressed while appropriately transmitting and refracting visible light.

[0105] The glass 10 according to the third aspect of this disclosure is the glass 10 according to the second aspect, and is expressed in mole percentage on an oxide basis, Bi ２ O ３ :25.0%~35.0% SiO ２ :0%~0.5% Al ２ O ３ : 0% to 0.5% B ２ O ３ :24.0%~30.0% P ２ O ５ :7.0%~12.0% Nb ２ O ５ :5.0%~9.0% TeO ２ :2.0%~15.0% ZnO:5.0%~13.0% ZrO ２ :2.0%~4.0% TiO ２ : Over 0% to 12.0% WO ３ : Over 0% to 2.0% RO: 0% to 2.0% R' ２ O: Contains 0% to 5.0%. According to this disclosure, cracking can be suppressed while improving optical properties. That is, cracking can be suppressed while appropriately transmitting and refracting visible light.

[0106] The glass 10 according to the fourth aspect of this disclosure is the glass 10 according to any of the first to third aspects, wherein the total content of Fe, Cr, and Ni is 5.0 ppm or less by mass. According to this disclosure, visible light can be appropriately transmitted.

[0107] The glass 10 according to the fifth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the fourth aspect, and the content of Pt is 1.5 ppm or less in mass representation. According to the present disclosure, visible light can be appropriately transmitted.

[0108] The glass 10 according to the sixth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the fifth aspect, and the content of Au is 50.0 ppm or less in mass representation. According to the present disclosure, visible light can be appropriately transmitted.

[0109] The glass 10 according to the seventh aspect of the present disclosure is the glass 10 according to any one of the first aspect to the sixth aspect, and the parameter A is 1.20 or more. According to the present disclosure, cracking can be more preferably suppressed.

[0110] The glass 10 according to the eighth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the seventh aspect, and the Young's modulus is 80 GPa or more. According to the present disclosure, cracking can be more preferably suppressed.

[0111] The glass 10 according to the ninth aspect of the present disclosure is the glass 10 according to the eighth aspect, and the Young's modulus is 83 GPa or more. According to the present disclosure, cracking can be more preferably suppressed.

[0112] The glass 10 according to the tenth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the ninth aspect, and the internal transmittance with respect to light having a wavelength of 450 nm converted to a thickness of 10 mm is 90% or more. According to the present disclosure, visible light can be appropriately transmitted to improve optical characteristics.

[0113] The glass 10 according to the eleventh aspect of the present disclosure is the glass 10 according to the tenth aspect, and the internal transmittance with respect to light having a wavelength of 450 nm converted to a thickness of 10 mm is 92% or more. According to the present disclosure, visible light can be appropriately transmitted to improve optical characteristics.

[0114] The glass 10 according to the twelfth aspect of the present disclosure is the glass 10 according to the eleventh aspect, and the internal transmittance with respect to light having a wavelength of 450 nm converted to a thickness of 10 mm is 93% or more. According to the present disclosure, visible light can be appropriately transmitted to improve optical characteristics.

[0115] The glass 10 according to the 13th aspect of this disclosure is the glass 10 according to the 12th aspect, wherein the internal transmittance for light with a wavelength of 450 nm, converted to a thickness of 10 mm, is 94% or more. According to this disclosure, visible light can be appropriately transmitted and optical properties can be improved.

[0116] The glass 10 according to the 14th aspect of this disclosure is the glass 10 according to any of the 1st to 13th aspects, wherein the refractive index of the d line n ｄ The value is 2.070 or higher. According to this disclosure, visible light can be appropriately refracted to improve optical properties.

[0117] The glass 10 according to the 15th aspect of this disclosure is the glass 10 according to any of the 1st to 14th aspects, and is used as a light guide plate. The glass 10 of this disclosure can be appropriately used as a light guide plate.

[0118] (Examples) Next, examples will be described. Tables 1 to 4 show the glass used in each example. The embodiments may be modified as long as the effects of the invention are achieved.

[0119]

[0120] (Example 1) In Example 1, glass with thicknesses of 7.0 mm and 1.2 mm was manufactured using the compositions listed in Table 1. Specifically, the raw materials with the compositions shown in Table 1 were uniformly mixed and melted in a gold crucible at 970°C for 2 hours to obtain uniform molten glass. Next, the molten glass was poured into a brass mold with dimensions of length × width × height = 40 mm length × 85 mm width × 20 mm height. After holding at 425°C for 1 hour, it was cooled to room temperature at a rate of approximately 1°C / minute to obtain a glass block. Next, the glass block was cut into 25mm x 25mm pieces using a cutting machine (small cutting machine manufactured by Maruto Co., Ltd.), and the plate thickness was adjusted and the surface polished using a grinding machine (SGM-6301 manufactured by Shuwa Kogyo Co., Ltd.) and a single-sided polishing machine (EJ-380IN manufactured by Nippon Engis Co., Ltd.), producing glass with dimensions of 25mm x 25mm and plate thicknesses of 7.0mm and 1.2mm.

[0121] For the glass in Example 1, the following parameters are used: optical basicity, glass transition temperature Tg, flexion point At, difference between flexion point At and glass transition temperature Tg (At - Tg), coefficient of linear expansion CTE (average coefficient of linear expansion from 100 to 300°C), specific gravity, Young's modulus, shear modulus, refractive index nd, and transmittance τ. ４４０ (Internal transmittance for light with a wavelength of 440 nm), transmittance τ ４５０ (Internal transmittance for light with a wavelength of 450 nm), transmittance τ ４６０ The internal transmittance (for light with a wavelength of 460 nm) and solarization property ΔT were measured using the method described in the above embodiment. The measurement results are shown in Table 1. Note that for refractive index nd, the underlined values ​​in the table are calculated values ​​obtained by performing linear regression on the measured refractive index nd and the glass composition.

[0122] (Examples 2 to 72) In Examples 2 to 72, the glass was manufactured and measured using the same method as in Example 1, except that the composition was as shown in Tables 1 to 4.

[0123] (Evaluation) Optical evaluation and fracture evaluation were performed on each example of glass. In the optical evaluation, the transmittance τ ４５０ A score of ○ was given if the material density was 85% or higher and the refractive index nd was 2.050 or higher, while a score of × was given if these conditions were not met. In the crack evaluation, a score of ○ was given if the Young's modulus was 75 GPa or higher, and a score of × was given if it was less than 75 GPa. The evaluation results for each example are shown in the table.

[0124] As shown in the table, in the examples 6-7, 15-17, 20-37, 41-50, and 53-72, both the optical evaluation and crack evaluation were positive, indicating that cracking can be suppressed while improving optical properties. On the other hand, in the comparative examples 1-5, 8-14, 18-19, 38-40, 51, and 52, at least one of the optical evaluation and crack evaluation was negative, indicating that cracking cannot be suppressed while improving optical properties. Note that crystallization occurred in 8 and 11-14, and phase separation occurred in 10, so they were not worth evaluating. ２ In examples 38-40, where the amount was less than 1.0%, and in examples 51 and 52, where parameter B was 30 or less, blackening occurred and the transmittance decreased significantly.

[0125] Although embodiments of the present invention have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above.

[0126] 10 Glass

Claims

1. The internal transmittance for light with a wavelength of 450 nm converted to a thickness of 10 mm is 85% or more, and the refractive index n of the d line ｄ is 2.050 or more, and it contains at least one of TiO ２ and Li ２ O, and in terms of molar percentage based on oxides, Bi ２ O ３ : 20.0% to 40.0% SiO ２ : 0% to 5.0% Al ２ O ３ : 0% to 5.0% B ２ O ３ : 15.0% to 35.0% P ２ O ５ : More than 0% to 20.0% Nb ２ O ５ : 0% to 12.0% TeO ２ : 1.0% to 30.0% ZnO: 0% to 20.0% ZrO ２ : 0% to 10.0% TiO ２ : 0% to 20.0% WO ３ : 0% to 7.5% RO: 0% to 7.0% R’ ２ O: 0% to 10.0%, and the parameter A represented by the formula (1) is 0.95 or more. A = ([B ２ O ３ × 2 + [P ２ O ５ × 2 + [Nb ２ O ５ × 2 + [ZrO ２ + [TiO ２ + [WO ３ + [RO] + [R’ ２ O] × 2) / ([Bi ２ O ３ × 2 + [Al ２ O ３ × 2 + [SiO ２ + [TeO ２ + [ZnO]) ··· (1) Here, RO is the total content of MgO, CaO, SrO, and BaO, and R’ ２ O is Li ２ O, Na ２ O, K ２ This is the total amount of oxygen (O).

2. Expressed as a mole percentage based on oxides, Bi ２ O ３ :25.0%~35.0% SiO ２ :0%~2.0% Al ２ O ３ : 0% to 2.0% B ２ O ３ :20.0%~32.0% P ２ O ５ :5.0%~15.0% Nb ２ O ５ :4.0%~10.0% TeO ２ :1.5%~20.0% ZnO:3.0%~15.0% ZrO ２ :1.0%~5.0% TiO ２ :0%~15.0% WO ３ :0%~5.0% RO:0%~5.0% R' ２ The glass according to claim 1, containing O: 0% to 7.0%.

3. In mole percentage based on oxides, Bi ２ O ３ :25.0%~35.0% SiO ２ :0%~0.5% Al ２ O ３ : 0% to 0.5% B ２ O ３ :24.0%~30.0% P ２ O ５ :7.0%~12.0% Nb ２ O ５ :5.0%~9.0% TeO ２ :2.0%~15.0% ZnO:5.0%~13.0% ZrO ２ :2.0%~4.0% TiO ２ : Over 0% to 12.0% WO ３ : Over 0% to 2.0% RO: 0% to 2.0% R' ２ The glass according to claim 2, containing O: 0% to 5.0%.

4. The glass according to claim 1, wherein the total content of Fe, Cr, and Ni is 5.0 ppm or less by mass.

5. The glass according to claim 1, wherein the Pt content is 1.0 ppm or less by mass.

6. The glass according to claim 1, wherein the Au content is 50.0 ppm or less by mass.

7. The glass according to claim 1, wherein parameter A is 1.20 or greater.

8. The glass according to claim 1, wherein the Young's modulus is 80 GPa or higher.

9. The glass according to claim 8, wherein the Young's modulus is 83 GPa or higher.

10. The glass according to claim 1, wherein the internal transmittance to light with a wavelength of 450 nm, converted to a thickness of 10 mm, is 90% or more.

11. The glass according to claim 10, wherein the internal transmittance for light with a wavelength of 450 nm, converted to a thickness of 10 mm, is 92% or more.

12. The glass according to claim 10, wherein the internal transmittance for light with a wavelength of 450 nm, converted to a thickness of 10 mm, is 93% or more.

13. The glass according to claim 10, wherein the internal transmittance for light with a wavelength of 450 nm, converted to a thickness of 10 mm, is 94% or more.

14. Refractive index of line d n ｄ The glass according to claim 1, wherein the ratio is 2.070 or higher.

15. The glass according to any one of claims 1 to 14, used as a light guide plate.

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