Glass and method for producing glass

Abstract

To suppress deposition of defects while achieving a high refractive index and a high transmittance. The glass (10) contains La2O3 and B2O3. The refractive index nd is 2.0100 or more. The total content of Bi2O3 and B2O3 is less than 80% expressed in mol% based on oxide. The total content of Pt and Fe is 0.5-15.0 ppm by mass ratio. Parameter A defined by formula (1) is 0.870 or more.

Description

Glass and glass manufacturing method

[0001] The present invention relates to glass and to a method for making glass.

[0002] In recent years, there has been a demand for glass with a high refractive index. In particular, in wearable devices such as head-mounted displays that realize AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc., a high refractive index for visible light is required for the light guide plate. For example, Patent Document 1 describes an optical glass with a refractive index of 1.64 to 1.85.

[0003] International Publication No. 2018 / 235725

[0004] However, glass with a high refractive index tends to have a low transmittance. Furthermore, glass with a high refractive index tends to have a high possibility of impurities and other substances precipitating as defects. Therefore, there is a need to suppress the precipitating of defects while achieving both a high refractive index and high transmittance.

[0005] An object of the present invention is to provide glass that can achieve a high refractive index and high transmittance while suppressing the precipitation of defects, and a method for manufacturing the glass.

[0006] The glass according to the present disclosure is ２ O ３ , and B ２ O ３ and the refractive index n ｄ is 2.010 or more, and Bi is ２ O ３ and B ２ O ３ The total content of Pt and Fe is less than 80%, the total content of Pt and Fe is 0.5 ppm or more and 15.0 ppm or less by mass ratio, and the parameter A shown in formula (1) is 0.870 or more.

[0007] A = τ ４４０ +0.005×(Pt+Fe)...(1)

[0008] A method for producing glass according to the present disclosure includes heating raw materials at a temperature of 950°C or higher and 1600°C or lower to melt the raw materials, and cooling the melted raw materials to obtain the glass.

[0009] According to the present invention, it is possible to suppress the deposition of defects while achieving a high refractive index and high transmittance.

[0010] Fig. 1 is a schematic diagram of the glass according to the present embodiment, and Fig. 2 is a cross-sectional view of the glass according to the present embodiment when it is made into a glass plate.

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments, and when there are multiple embodiments, the present invention also includes combinations of the embodiments. Numerical values ​​include rounded ranges. Numerical ranges expressed as "to" refer to a range that includes the numbers before and after "to" as the lower and upper limits, and the same meaning will be used hereafter. In the present embodiment, the lower and upper limits can be combined as appropriate.

[0012] (Glass) FIG. 1 is a schematic diagram of glass according to this embodiment. As shown in FIG. 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 any shape. 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] (Refractive index n ｄ ) Refractive index n of glass 10 ｄ is 2.0100 or more, preferably 2.0150 or more, more preferably 2.0200 or more, more preferably 2.0250 or more, more preferably 2.0300 or more, more preferably 2.0350 or more, and more preferably 2.0400 or more.ｄ is preferably 2.2000 or less, more preferably 2.1800 or less, more preferably 2.1600 or less, more preferably 2.1400 or less, more preferably 2.1200 or less, more preferably 2.1100 or less, and more preferably 2.0600 or less. ｄ is preferably 2.0150 or more and 2.2000 or less, more preferably 2.0200 or more and 2.1800 or less, more preferably 2.0250 or more and 2.1600 or less, more preferably 2.0300 or more and 2.1400 or less, more preferably 2.0350 or more and 2.1200 or less, and more preferably 2.0400 or more and 2.0600 or less. ｄ When the refractive index n is in this range, the refractive index becomes high for visible light, and the glass 10 can be given appropriate optical properties. ｄ The refractive index n is the refractive index at the d line of helium (wavelength 587.6 nm). ｄ can be measured by the V-block method.

[0014] (Parameter A) The parameter A of the glass 10 is expressed by the following formula (1).

[0015] A = τ ４４０ +0.005×(Pt+Fe)...(1)

[0016] τ in Equation (1) ４４０ is the internal transmittance for light with a wavelength of 440 nm when converted into a thickness of 10 mm. Also, (Pt+Fe) is the ratio (ppm) of the total content of Pt and Fe to the entire glass 10 in mass ratio.

[0017] The parameter A defined by formula (1) is a value of 0.870 or more. The parameter A is preferably 0.880 or more, more preferably 0.890 or more, more preferably 0.900 or more, more preferably 0.910 or more, more preferably 0.920 or more, and more preferably 0.930 or more, whereby both the internal transmittance of the glass and appropriate manufacturing conditions are achieved, which is preferable.

[0018] Glass 10 can maintain a high transmittance for visible light even when it contains Pt or Fe, by having parameter A, which defines the relationship between the total content of Pt and Fe and the transmittance, fall within the above range.

[0019] The internal transmittance is the transmittance that passes through the inside of the glass 10. The internal transmittance can be calculated from the measured values ​​of the external transmittances of two types of glass with different plate thicknesses and the following formula (A). The external transmittance means the transmittance including the 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 external transmittances, and Δd is the difference in thickness of the sample. The external transmittance can be measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technologies Corporation) for a sample that has been mirror-polished on both sides to a plate thickness of 10 mm.

[0020]

[0021] Furthermore, Pt and Fe herein do not refer only to the Pt and Fe elemental metals contained in the glass 10, but may also include the Pt and Fe elemental metals and compounds. In other words, the total content of Pt and Fe can be said to include the content of the Pt and Fe elemental metals and the content of Pt and Fe ions in the compounds. The Pt and Fe contents can be measured by ICP mass spectrometry. As a measuring instrument, for example, an Agilent 8800 manufactured by Agilent Technologies can be used. Measurement was performed according to the following procedure.

[0022] To measure the content, a mixed acid of hydrofluoric acid and sulfuric acid is added to the crushed glass 10 and heated to decompose it. After decomposition, hydrochloric acid is added to a fixed amount, and the concentration of the measured element is measured by ICP mass spectrometry. The concentration is calculated using a calibration curve created using a standard solution. The concentration of the measured element in the glass 10 can be calculated from this measured concentration and the amount of decomposition of the glass 10. Subsequent elements can be measured using the same procedure.

[0023] (Parameter B) The parameter B of the glass 10 is expressed by the following formula (2).

[0024] B = τ ４６０ +0.583 x nｄ ... (2) where τ ４６０ is the internal transmittance for light with a wavelength of 460 nm when converted to a thickness of 10 mm, and n ｄ is the refractive index n of the glass 10 ｄ is.

[0025] The parameter B in formula (2) is a value of 2.075 or more. The parameter B is preferably 2.080 or more, more preferably 2.090 or more, more preferably 2.100 or more, more preferably 2.105 or more, more preferably 2.112 or more, more preferably 2.115 or more, more preferably 2.117 or more, more preferably 2.118 or more, more preferably 2.124 or more, more preferably 2.127 or more, and more preferably 2.130 or more, which is preferable because a wide viewing angle and a clear image can be obtained.

[0026] When the parameter B, which indicates the relationship between the refractive index and the transmittance, falls within the above range, the glass 10 can maintain a high transmittance for visible light even if it has a high refractive index.

[0027] (Composition) The composition of the glass 10 will be described below.

[0028] (La ２ O ３ and B ２ O ３ ) The glass 10 is La ２ O ３ and B ２ O ３ Includes: ２ O ３ and B ２ O ３ By including La, a high refractive index and a high transmittance can be appropriately achieved. ２ O ３ and B ２ O ３ Whether or not a compound contains the compound can be measured by ICP mass spectrometry. As a measuring device, for example, Agilent 8800 manufactured by Agilent Technologies can be used.

[0029] (Pt and Fe) The total content of Pt and Fe in the glass 10, by mass ratio, relative to the entire glass 10, is 0.5 ppm to 15.0 ppm, preferably 1.0 ppm or more, more preferably 2.0 ppm or more, more preferably 3.0 ppm or more, more preferably 4.0 ppm or more, more preferably 5.0 ppm or more, and more preferably 6.0 ppm or more. The total content of Pt and Fe in the glass 10, by mass ratio, relative to the entire glass 10, is preferably 14.0 ppm or less, more preferably 13.0 ppm or less, more preferably 12.0 ppm or less, more preferably 11.0 ppm or less, more preferably 10.0 ppm or less, and more preferably 9.0 ppm or less. The total content of Pt and Fe in glass 10, in terms of mass ratio, relative to the entire glass 10, is preferably 1.0 ppm to 14.0 ppm, more preferably 2.0 ppm to 13.0 ppm, more preferably 3.0 ppm to 12.0 ppm, more preferably 4.0 ppm to 11.0 ppm, more preferably 5.0 ppm to 10.0 ppm, and more preferably 6.0 ppm to 9.0 ppm. By setting the upper limits of Pt and Fe within these ranges, it is possible to suppress the precipitation of Pt and Fe as defects. Furthermore, by setting the lower limits of Pt and Fe within these ranges, it is possible to use materials containing Pt and Fe for raw materials and equipment such as crucibles during production, allowing for appropriate production.

[0030] (Bi ２ O ３ and B ２ O ３ Glass 10 contains, in mole percent on an oxide basis, Bi. ２ O ３ and B ２ O ３ The total content of Bi is less than 80.0%, preferably 75.0% or less, more preferably 70.0% or less, more preferably 65.0% or less, more preferably 60.0% or less, more preferably 55.0% or less, more preferably 50.0% or less, and even more preferably 45.0% or less. ２ O ３ and B２ O ３ The total content of Bi and Si is preferably 0% or more, more preferably 1.5% or more, more preferably 5.0% or more, more preferably 10.0% or more, more preferably 15.0% or more, more preferably 20.0% or more, and even more preferably 25.0% or more. ２ O ３ and B ２ O ３ The total content of Bi is preferably 0% or more and 75.0% or less, more preferably 1.5% or more and 70.0% or less, more preferably 5.0% or more and 65.0% or less, more preferably 10.0% or more and 60.0% or less, more preferably 15.0% or more and 55.0% or less, more preferably 20.0% or more and 50.0% or less, and more preferably 25.0% or more and 45.0% or less. ２ O ３ and B ２ O ３ When the total content of and is within this range, a high refractive index and a high transmittance can be appropriately achieved.

[0031] (Preferred Composition) The preferred composition of the glass 10 will be described in detail below.

[0032] (SiO ２ ) The glass 10 is SiO ２ The glass 10 preferably contains, in mole percent on an oxide basis, SiO ２ The content of is preferably 0% or more, more preferably 1.0% or more, more preferably 2.0% or more, more preferably 3.0% or more, more preferably 4.0% or more, more preferably 5.0% or more, more preferably 6.0% or more, and even more preferably 7.0% or more. The glass 10 contains, in mole % on an oxide basis, SiO ２The content of is preferably 20.0% or less, more preferably 19.0% or less, more preferably 18.0% or less, more preferably 17.0% or less, more preferably 16.0% or less, more preferably 15.0% or less, more preferably 14.0% or less, preferably 13.0% or less, and even more preferably 10.0% or less. ２ The content of SiO is preferably 0% or more and 20.0% or less, more preferably 1.0% or more and 19.0% or less, more preferably 2.0% or more and 18.0% or less, more preferably 3.0% or more and 17.0% or less, more preferably 4.0% or more and 16.0% or less, more preferably 5.0% or more and 15.0% or less, more preferably 6.0% or more and 14.0% or less, preferably 7.0% or more and 13.0% or less, and even more preferably 7.0% or more and 10.0% or less. ２ When the content of falls within this range, the coloring of the glass is reduced and the transmittance of short-wavelength visible light is increased, and stable glass formation is promoted, improving the devitrification resistance of the glass.

[0033] (B ２ O ３ ) Glass 10 is B ２ O ３ The glass 10 preferably contains, in mole percent on an oxide basis, B ２ O ３ The content of is preferably 0% or more, more preferably 1.5% or more, more preferably 3.5% or more, more preferably 5.0% or more, more preferably 7.5% or more, more preferably 10.0% or more, more preferably 12.0% or more, more preferably 13.0% or more, more preferably 14.0% or more, more preferably 15.0% or more, and even more preferably 16.0% or more. The glass 10 has a content of B, expressed in mole percent on an oxide basis. ２ O ３The content of is preferably 30.0% or less, more preferably 28.0% or less, more preferably 26.0% or less, more preferably 24.0% or less, more preferably 22.0% or less, more preferably 21.0% or less, more preferably 20.0% or less, and even more preferably 19.5% or less. The glass 10 contains, in mole percent on an oxide basis, B ２ O ３ The content of is preferably 0% or more and 30.0% or less, more preferably 1.5% or more and 28.0% or less, more preferably 3.5% or more and 26.0% or less, more preferably 5.0% or more and 24.0% or less, more preferably 7.5% or more and 22.0% or less, more preferably 10% or more and 21.0% or less, more preferably 12% or more and 20.0% or less, more preferably 14% or more and 20.0% or less, and even more preferably 16% or more and 19.5% or less. B ２ O ３ When the content of falls within this range, the coloring of the glass is reduced and the transmittance of short-wavelength visible light is increased, and stable glass formation is promoted, improving the devitrification resistance of the glass.

[0034] (Y ２ O ３ ) Glass 10 is Y ２ O ３ The glass 10 preferably contains, in mole percent on an oxide basis, Y. ２ O ３ The content of Y is preferably 0% or more, more preferably 0.5% or more, more preferably 1.0% or more, more preferably 1.5% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. The glass 10 contains, in mole percent on an oxide basis, ２ O ３The content of Y is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, more preferably 5.0% or less, more preferably 4.5% or less, preferably 4.0% or less, and even more preferably 3.0% or less. ２ O ３ The content of is preferably 0% or more and 10.0% or less, more preferably 0.5% or more and 8.0% or less, more preferably 1.0% or more and 6.0% or less, more preferably 1.5% or more and 5.0% or less, more preferably 2.0% or more and 4.5% or less, even more preferably 2.5% or more and 4.0% or less, and even more preferably 2.5% or more and 3.0% or less. ２ O ３ When the content falls within this range, the refractive index and devitrification resistance of the glass are improved.

[0035] (BaO) The glass 10 may contain BaO or may not contain BaO. The BaO content of the glass 10, expressed in mole percent on an oxide basis, is preferably 0% or more, more preferably 0.5% or more, more preferably 1.0% or more, more preferably 1.5% or more, more preferably 2.0% or more, more preferably 2.5% or more, and even more preferably 3.0% or more. The BaO content of the glass 10, expressed in mole percent on an oxide basis, is preferably 10% or less, more preferably 9.0% or less, more preferably 8.0% or less, more preferably 7.0% or less, more preferably 6.0% or less, more preferably 5.0% or less, and even more preferably 4.0% or less. Glass 10 preferably has a BaO content, expressed in mole percent on an oxide basis, of 0% to 10%, more preferably 0.5% to 9.0%, more preferably 1.0% to 8.0%, more preferably 1.5% to 7.0%, more preferably 2.0% to 6.0%, more preferably 2.5% to 5.0%, and even more preferably 3.0% to 4.0%. When the BaO content is within this range, the refractive index, devitrification resistance, and visible light transmittance of the glass are improved.

[0036] (Bi ２ O ３ ) Glass 10 is Bi ２ O ３ or Bi ２ O ３ The glass 10 may contain, in mole percent on an oxide basis, Bi. ２ O ３ The content of Bi is preferably 0% or more, more preferably 0.5% or more, more preferably 1.0% or more, more preferably 2.0% or more, more preferably 4.0% or more, and even more preferably 6.0% or more. The glass 10 contains, in mole percent on an oxide basis, Bi ２ O ３The content of Bi is preferably 30.0% or less, more preferably 25.0% or less, more preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 10.0% or less. ２ O ３ The content of Bi is preferably 0% or more and 30.0% or less, more preferably 0.5% or more and 25.0% or less, more preferably 1.0% or more and 20.0% or less, more preferably 2.0% or more and 20.0% or less, more preferably 4.0% or more and 15.0% or less, and even more preferably 6.0% or more and 10.0% or less. ２ O ３ When the content falls within this range, a high refractive index and a high transmittance can be appropriately achieved.

[0037] (Gd ２ O ３ ) Glass 10 is Gd ２ O ３ The glass 10 preferably contains, in mole percent on an oxide basis, Gd ２ O ３ The content of Gd is preferably 0% or more, more preferably 1.0% or more, more preferably 2.0% or more, more preferably 3.0% or more, more preferably 4.0% or more, and even more preferably 4.5% or more. ２ O ３ The content of Gd is preferably 10% or less, more preferably 9.0% or less, more preferably 8.0% or less, more preferably 7.0% or less, preferably 6.0% or less, and even more preferably 5.0% or less. ２ O ３The content of Gd is preferably 0% or more and 10% or less, more preferably 1.0% or more and 9.0% or less, more preferably 2.0% or more and 8.0% or less, more preferably 3.0% or more and 7.0% or less, even more preferably 4.0% or more and 6.0% or less, and even more preferably 4.5% or more and 5.0% or less. ２ O ３ When the content falls within this range, the refractive index and devitrification resistance of the glass are improved.

[0038] (Nb ２ O ５ ) Glass 10 is Nb ２ O ５ The glass 10 preferably contains, in mole percent on an oxide basis, Nb ２ O ５ The content of Nb is preferably 0% or more, more preferably 1.0% or more, more preferably 2.0% or more, more preferably 3.0% or more, more preferably 4.0% or more, and even more preferably 4.5% or more. ２ O ５ The content of Nb is preferably 10.0% or less, more preferably 9.0% or less, more preferably 8.0% or less, more preferably 7.0% or less, more preferably 6.0% or less, and even more preferably 5.5% or less. ２ O ５ The content of Nb is preferably 0% or more and 10.0% or less, more preferably 1.0% or more and 9.0% or less, more preferably 2.0% or more and 8.0% or less, even more preferably 3.0% or more and 7.0% or less, preferably 4.0% or more and 6.0% or less, even more preferably 5.0% or more and 6.0% or less, and also preferably 4.5% or more and 5.5% or less. ２ O ５ When the content falls within this range, the refractive index and devitrification resistance of the glass are improved.

[0039] (ZnO) The glass 10 preferably contains ZnO. The ZnO content of the glass 10, expressed in mole percent on an oxide basis, is preferably 0% or more, more preferably 1.0% or more, more preferably 2.0% or more, and even more preferably 3.0% or more. The ZnO content of the glass 10, expressed in mole percent on an oxide basis, is preferably 20.0% or less, more preferably 15.0% or less, more preferably 10.0% or less, and even more preferably 6.0% or less. The ZnO content of the glass 10, expressed in mole percent on an oxide basis, is preferably 0% or more and 20.0% or less, more preferably 1.0% or more and 15.0% or less, more preferably 2.0% or more and 10% or less, and even more preferably 3.0% or more and 6.0% or less. When the ZnO content is within this range, the liquidus temperature of the glass is lowered, thereby suppressing defect precipitation.

[0040] (W.O. ３ ) Glass 10 is WO ３ or WO ３ The glass 10 may contain, in mole percent on an oxide basis, WO ３ The content of WO is preferably 0% or more, more preferably 0.1% or more, more preferably 0.2% or more, still more preferably 0.3% or more, and even more preferably 0.5% or more. ３ The content of WO is preferably 30.0% or less, more preferably 20.0% or less, more preferably 10.0% or less, more preferably 2.00% or less, and even more preferably 1.0% or less. ３ The content of WO is preferably 0% or more and 30.0% or less, more preferably 0.1% or more and 20.0% or less, even more preferably 0.2% or more and 10.0% or less, still more preferably 0.3% or more and 2.0% or less, and even more preferably 0.5% or more and 1.0% or less. ３ When the content falls within this range, a lower liquidus temperature and a high refractive index of the glass can be appropriately achieved.

[0041] (Ta ２ O ５ ) The glass 10 is Ta ２ O ５ may contain Ta ２ O ５ The glass 10 may contain, in mole percent on an oxide basis, Ta. ２ O ５ The content of Ta is preferably 0% or more, more preferably 0.1% or more, even more preferably 0.2% or more, and still more preferably 0.3% or more. The glass 10 contains, in mole percent on an oxide basis, Ta ２ O ５ The content of Ta is preferably 10.0% or less, more preferably 5.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less. ２ O ５ The content of Ta is preferably 0% or more and 10.0% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.2% or more and 1.0% or less, and still more preferably 0.3% or more and 0.5% or less. ２ O ５ When the content of falls within this range, a high refractive index and reduced manufacturing costs for the glass can be appropriately achieved.

[0042] (P ２ O ５ ) Glass 10 is P ２ O ５ or P ２ O ５ The glass 10 may contain, in mole percent on an oxide basis, P. ２ O ５ The content of P is preferably 0% or more, more preferably 0.5% or more, more preferably 1.0% or more, more preferably 1.5% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. ２ O ５The content of P is preferably 30.0% or less, more preferably 25.0% or less, more preferably 20.0% or less, more preferably 15.0% or less, more preferably 10.0% or less, and even more preferably 5.0% or less. ２ O ５ The content of P is preferably 0% or more and 30.0% or less, more preferably 0.5% or more and 25.0% or less, more preferably 1.0% or more and 20.0% or less, more preferably 1.5% or more and 15.0% or less, more preferably 2.0% or more and 10.0% or less, and even more preferably 2.5% or more and 5.0% or less. ２ O ５ When the content of falls within this range, the coloring of the glass is reduced and the transmittance of short-wavelength visible light is increased, and stable glass formation is promoted, improving the devitrification resistance of the glass.

[0043] (ZrO ２ ) Glass 10 is ZrO ２ The glass 10 preferably contains, in mole percent on an oxide basis, ZrO ２ The content of ZrO is preferably 0% or more, more preferably 1.0% or more, more preferably 2.0% or more, more preferably 3.0% or more, more preferably 4.0% or more, more preferably 5.0% or more, more preferably 6.0% or more, and even more preferably 7.0% or more. ２ The content of ZrO is preferably 15.0% or less, more preferably 14.0% or less, more preferably 13.0% or less, more preferably 12.0% or less, more preferably 11.0% or less, more preferably 10.0% or less, more preferably 9.0% or less, and even more preferably 8.0% or less. ２The content of ZrO is preferably 0% or more and 15.0% or less, more preferably 1.0% or more and 14.0% or less, more preferably 2.0% or more and 13.0% or less, more preferably 3.0% or more and 12.0% or less, more preferably 4.0% or more and 11.0% or less, more preferably 5.0% or more and 10.0% or less, more preferably 6.0% or more and 9.0% or less, and even more preferably 7.0% or more and 8.0% or less. ２ When the content of falls within this range, coloration of the glass is reduced and the transmittance of short-wavelength visible light is increased, and stable glass formation is promoted, thereby improving the devitrification resistance of the glass.

[0044] (TiO ２ ) Glass 10 is TiO ２ The glass 10 preferably contains, in mole percent on an oxide basis, TiO ２ The content of TiO is preferably 0% or more, more preferably 5.0% or more, more preferably 10.0% or more, more preferably 15.0% or more, more preferably 20.0% or more, preferably 25.0% or more, preferably 28.0% or more, preferably 29.0% or more, preferably 30.0% or more, and even more preferably 31.0% or more. ２ The content of TiO is preferably 40.0% or less, more preferably 35.0% or less, more preferably 34.0% or less, more preferably 33.0% or less, more preferably 32.0% or less, preferably 31.5% or less, and even more preferably 31.0% or less. ２The content of TiO is preferably 0% or more and 40% or less, more preferably 5.0% or more and 35% or less, more preferably 10% or more and 34.0% or less, more preferably 15.0% or more and 33.0% or less, more preferably 20.0% or more and 32.0% or less, preferably 25.0% or more and 32.0% or less, preferably 28.0% or more and 32.0% or less, preferably 29.0% or more and 32.0% or less, even more preferably 30.0% or more and 32.0% or less, preferably 31.0% or more and 31.5% or less, and even more preferably 31.0%. ２ When the content falls within this range, the refractive index and chemical durability of the glass are improved.

[0045] (La ２ O ３ ) The glass 10 is La ２ O ３ The glass 10 preferably contains, in mole percent on an oxide basis, La. ２ O ３ The content of La is preferably 0% or more, more preferably 5.0% or more, more preferably 10.0% or more, more preferably 15.0% or more, more preferably 16.0% or more, more preferably 17.0% or more, more preferably 18.0% or more, more preferably 19.0% or more, and even more preferably 20.0% or more. The glass 10 contains, in mole % on an oxide basis, La ２ O ３ The content of La is preferably 40.0% or less, more preferably 35.0% or less, more preferably 30.0% or less, more preferably 28.0% or less, more preferably 27.0% or less, more preferably 26.0% or less, more preferably 25.0% or less, preferably 24.0% or less, and even more preferably 22.0% or less. ２ O ３The content of La is preferably 0% or more and 40.0% or less, more preferably 5.0% or more and 35.0% or less, more preferably 10.0% or more and 35.0% or less, more preferably 15.0% or more and 30.0% or less, more preferably 16.0% or more and 28.0% or less, more preferably 17.0% or more and 27.0% or less, more preferably 18.0% or more and 26.0% or less, more preferably 19.0% or more and 25.0% or less, even more preferably 20.0% or more and 24.0% or less, and even more preferably 20.0% or more and 22.0% or less. ２ O ３ When the content falls within this range, a high refractive index and improved chemical durability can be appropriately achieved.

[0046] (Ti ３＋ / Ti) In the above description, when Ti is contained in the glass 10, the contained Ti is expressed as TiO ２ (i.e., all Ti is tetravalent Ti (Ti ４＋ However, the content of Ti was specified assuming that all Ti was in the tetravalent state (Ti ４＋ ), and at least a part of Ti is, for example, trivalent Ti (Ti ３＋ In this case, the ratio of trivalent Ti (Ti ３＋ ) content ratio (Ti ３＋ / Ti) is preferably less than 0.100 in mass ratio, more preferably 0.0800 or less, more preferably 0.0600 or less, more preferably 0.0500 or less, more preferably 0.0400 or less, more preferably 0.0300 or less, more preferably 0.0200 or less, and even more preferably 0.0100 or less. ３＋ / Ti) is more preferably 0 or more, more preferably 0.0005 or more, more preferably 0.0010 or more, more preferably 0.0020 or more, more preferably 0.0040 or more, more preferably 0.0060 or more, and even more preferably 0.0080 or more, in terms of mass ratio. ３＋ / Ti) is preferably less than 0.100 in mass ratio, more preferably 0 or more and 0.0800 or less, more preferably 0.0005 or more and 0.0600 or less, more preferably 0.0010 or more and 0.0500 or less, more preferably 0.0020 or more and 0.0400 or less, more preferably 0.0040 or more and 0.0300 or less, more preferably 0.0060 or more and 0.0200 or less, and even more preferably 0.0080 or more and 0.0100 or less. When the content of trivalent Ti is within this range, a high refractive index and high transmittance can be appropriately achieved. Note that the total content of Ti refers to the total content of all valent Ti, such as divalent, trivalent, and tetravalent. The Ti content can be measured by ICP mass spectrometry. As a measuring instrument, for example, an Agilent 8800 manufactured by Agilent Technologies can be used. Ti ３＋ The content of can be measured by an electron spin resonance (ESR) apparatus. As a measuring device, for example, EMX nano manufactured by Bruker Corporation can be used. The ESR measurement conditions used in the above-mentioned experiment are described below.

[0047] Ti ３＋The content of was determined by integrating the peak at g = 1.93 ± 0.01 twice to determine its intensity, and comparing it with the intensity determined in the same way for a standard sample of known concentration. g refers to the value calculated using the following formula. The integration range is set so that only the peak is integrated. g = hν / βH (where h is Planck's constant, ν is the microwave frequency, β is the Bohr magneton of the electron, and H is the absorbed magnetic field.) Sample amount: 0.5 g Microwave frequency: 9.57-9.60 GHz (adjusted for each measurement) Output: 1-10 mW (adjusted for each measurement) Sweep range: 1000-4000 gauss Modulation frequency: 100 kHz Modulation magnetic field: 5 gauss Magnetic field sweep time: 30-60 sec (adjusted for each measurement) Time constant: 1.28 msec Measurement temperature: room temperature

[0048] In addition, the ratio of tetravalent Ti (Ti ４＋ ) content ratio (Ti ４＋ / Ti) is preferably 0.9000 or more, more preferably 0.9200 or more, even more preferably 0.9400 or more, and even more preferably 0.9600 or more, in mass ratio. ４＋ / Ti) is preferably 1.0000 or less, more preferably 0.9950 or less, even more preferably 0.9900 or less, and still more preferably 0.9850 or less, in mass ratio. ４＋ / Ti) is preferably 0.9000 or more and 1.0000 or less, more preferably 0.9200 or more and 0.9950 or less, more preferably 0.9400 or more and 0.9900 or less, and even more preferably 0.9600 or more and 0.9850 or less, in terms of mass ratio. When the content of tetravalent Ti is within this range, a high refractive index and a high transmittance can be appropriately achieved.

[0049] (Sb) The glass 10 preferably does not contain Sb. By not containing Sb, the burden on the environment can be appropriately reduced. Note that "not containing Sb" means that the inclusion of Sb as an unavoidable impurity is permitted. Here, Sb does not refer only to the simple metal Sb contained in the glass 10, but may also include simple metal Sb and compounds. Whether or not Sb is contained can be measured by ICP mass spectrometry. As a measuring instrument, for example, an Agilent 8800 manufactured by Agilent Technologies can be used.

[0050] (Glass Characteristics) The characteristics of the glass 10 other than those described above will be described below.

[0051] (Transmittance τ ４４０ ) Transmittance τ of glass 10 ４４０ is preferably 0.800 or more, more preferably 0.820 or more, more preferably 0.840 or more, more preferably 0.860 or more, more preferably 0.870 or more, more preferably 0.880 or more, more preferably 0.890 or more, and even more preferably 0.900 or more. ４４０ is preferably 1.000 or less, more preferably 0.990 or less, more preferably 0.980 or less, more preferably 0.970 or less, more preferably 0.965 or less, more preferably 0.960 or less, and even more preferably 0.955 or less. ４４０ is preferably 0.820 or more and 1.000 or less, more preferably 0.840 or more and 0.990 or less, more preferably 0.860 or more and 0.980 or less, more preferably 0.870 or more and 0.970 or less, more preferably 0.880 or more and 0.965 or less, more preferably 0.890 or more and 0.960 or less, and even more preferably 0.900 or more and 0.955 or less. ４４０ When the transmittance τ is in this range, visible light can be transmitted appropriately. ４４０As described above, λ is the internal transmittance for light with a wavelength of 440 nm when converted into a thickness of 10 mm.

[0052] (Transmittance τ ４６０ ) Transmittance τ of glass 10 ４６０ is preferably 0.850 or more, more preferably 0.870 or more, more preferably 0.890 or more, more preferably 0.900 or more, more preferably 0.910 or more, more preferably 0.920 or more, and even more preferably 0.930 or more. ４６０ is preferably 1.000 or less, more preferably 0.990 or less, more preferably 0.980 or less, more preferably 0.975 or less, more preferably 0.970 or less, and even more preferably 0.965 or less. ４６０ is preferably 0.870 or more and 1.000 or less, more preferably 0.890 or more and 0.990 or less, more preferably 0.900 or more and 0.980 or less, more preferably 0.910 or more and 0.975 or less, more preferably 0.920 or more and 0.970 or less, and even more preferably 0.930 or more and 0.965 or less. ４６０ When the transmittance τ is in this range, visible light can be transmitted appropriately. ４６０ As described above, is the internal transmittance for light with a wavelength of 460 nm when converted into a thickness of 10 mm.

[0053] (wavelength λ ５ ) Wavelength λ of glass 10 ５ The wavelength λ of the glass 10 is preferably 430 nm or less, more preferably 425 nm or less, more preferably 420 nm or less, more preferably 415 nm or less, more preferably 410 nm or less, and even more preferably 405 nm or less. ５is more preferably 350 nm or more, more preferably 355 nm or more, more preferably 360 nm or more, more preferably 365 nm or more, and even more preferably 370 nm or more. ５ The wavelength λ is preferably 430 nm or less, more preferably 350 nm or more and 425 nm or less, more preferably 355 nm or more and 420 nm or less, more preferably 360 nm or more and 415 nm or less, more preferably 365 nm or more and 410 nm or less, and even more preferably 370 nm or more and 405 nm or less. ５ When the wavelength λ is in this range, visible light can be transmitted appropriately. ５ refers to the wavelength at which the internal transmittance is 5% at a plate thickness (thickness) of 10 mm.

[0054] (Abbe number v ｄ ) Abbe number v of glass 10 ｄ is preferably 17.00 or more, more preferably 19.00 or more, more preferably 23.00 or more, more preferably 25.00 or more, more preferably 26.00 or more, and even more preferably 27.00 or more. ｄ is preferably 35.00 or less, more preferably 33.00 or less, more preferably 32.00 or less, more preferably 31.00 or less, more preferably 30.00 or less, and even more preferably 29.00 or less. ｄ is preferably 17.00 or more and 35.00 or less, more preferably 19.00 or more and 33.00 or less, more preferably 23.00 or more and 32.00 or less, more preferably 25.00 or more and 31.00 or less, more preferably 26.00 or more and 30.00 or less, and even more preferably 27.00 or more and 29.00 or less. ｄ is a value that represents the properties related to dispersion. ｄ can be measured by the V-block method.

[0055] (Devitrification Temperature) The devitrification temperature of the glass 10 is preferably 1250°C or less, more preferably 1240°C or less, more preferably 1230°C or less, more preferably 1220°C or less, more preferably 1210°C or less, more preferably 1200°C or less, more preferably 1190°C or less, more preferably 1180°C or less, more preferably 1170°C or less, more preferably 1160°C or less, more preferably 1150°C or less, more preferably 1140°C or less, more preferably 1130°C or less, and even more preferably 1120°C or less. When the devitrification temperature is in this range, the temperature at which the raw materials are melted during the production of the glass 10 can be relatively low, and the Pt and Fe contained in the raw materials and equipment can be prevented from being dissolved and mixed into the glass, thereby reducing the content of Pt and Fe. The devitrification temperature can be measured by the method shown below. The sample glass was crushed to obtain glass particles that passed through a 4 mm sieve and remained on a 2 mm sieve. The glass particles were immersed in ethanol, ultrasonically cleaned, and then dried in a dryer. Approximately 5 g of the dried glass particles were placed in a platinum dish and held at temperatures from 1000 to 1400 °C in 10 °C increments for 1 hour. After cooling by natural cooling, the presence or absence of crystal precipitation was observed under a microscope, and the lowest temperature at which crystals with a long side or major axis of 1 μm or more were not observed was defined as the devitrification temperature.

[0056] (Young's modulus E) The Young's modulus E of the glass 10 is preferably 90 GPa or more, more preferably 95 GPa or more, more preferably 100 GPa or more, more preferably 105 GPa or more, more preferably 110 GPa or more, more preferably 117 GPa or more, more preferably 120 GPa or more, more preferably 122 GPa or more, more preferably 124 GPa or more, and even more preferably 126 GPa or more. The Young's modulus E of the glass 10 is preferably 155 GPa or less, more preferably 150 GPa or less, more preferably 148 GPa or less, more preferably 145 GPa or less, more preferably 143 GPa or less, more preferably 141 GPa or less, more preferably 139 GPa or less, more preferably 137 GPa or less, and even more preferably 135 GPa or less. The Young's modulus E of the glass 10 is preferably 95 GPa or more and 155 GPa or less, more preferably 100 GPa or more and 150 GPa or less, more preferably 105 GPa or more and 148 GPa or less, more preferably 110 GPa or more and 145 GPa or less, more preferably 117 GPa or more and 143 GPa or less, more preferably 120 GPa or more and 141 GPa or less, more preferably 122 GPa or more and 139 GPa or less, more preferably 124 GPa or more and 137 GPa or less, and even more preferably 126 GPa or more and 135 GPa or less. Such a high Young's modulus can appropriately suppress breakage of the glass 10. The Young's modulus can be measured based on the propagation of ultrasonic waves using a 38DL PLUS manufactured by Olympus Corporation.

[0057] (Specific Gravity d) The specific gravity d of the glass 10 is 6.20 g / cm ３ Preferably, it is 6.17 g / cm or less. ３ More preferably, it is 5.70 g / cm or less. ３ More preferably, it is 5.50 g / cm or less. ３ More preferably, it is 5.40 g / cm or less. ３More preferably, it is 5.30 g / cm or less. ３ More preferably, it is 5.20 g / cm or less. ３ Preferably, it is 5.00 g / cm or less. ３ The specific gravity d of the glass 10 is 3.40 g / cm or less, more preferably 4.50 or less. ３ It is preferable that the density is 3.50 g / cm or more. ３ More preferably, it is 3.60 g / cm or more. ３ More preferably, it is 3.70 g / cm or more. ３ More preferably, it is 3.80 g / cm or more. ３ More preferably, it is 3.90 g / cm or more. ３ The specific gravity d of the glass 10 is more preferably 3.40 g / cm or more. ３ 6.17g / cm or more ３ Preferably, it is 3.50 g / cm or less. ３ 5.70g / cm or more ３ More preferably, it is 3.60 g / cm or less. ３ 5.50g / cm or more ３ More preferably, it is 3.70 g / cm or less. ３ 5.40g / cm or more ３ More preferably, it is 3.80 g / cm or less. ３ 5.30g / cm or more ３ More preferably, it is 3.90 g / cm or less. ３ 5.20g / cm or more ３ Preferably, it is 4.00 g / cm or less. ３ 5.00g / cm or more ３ It is even more preferable that the specific gravity is equal to or less than 0.5 g / cm. Such a low specific gravity makes it easy to handle the glass 10. The specific gravity d can be measured by Archimedes' method.

[0058] (Glass Form) The glass 10 according to this embodiment is preferably an optical glass, and is preferably a glass plate having a thickness of 0.01 mm or more and 2.0 mm or less. A thickness of 0.01 mm or more can prevent breakage of the glass 10 during handling or processing. In addition, deflection of the glass 10 due to its own weight can be reduced. 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, a thickness of 2.0 mm or less can reduce the weight of an optical element using the glass 10. This thickness is more preferably 1.5 mm or less, even more preferably 1.0 mm or less, and even more preferably 0.8 mm or less.

[0059] When the glass 10 according to this embodiment is a glass plate, the area of ​​the main surface is 8 cm ２ This area is preferably 8cm or more. ２ If the area is more than 30 cm, a large number of optical elements can be arranged, improving productivity. ２ More preferably, it is 170 cm or more. ２ More preferably, it is 300 cm or more. ２ More preferably, it is 1000 cm ２ On the other hand, the area is 6500 cm ２ If the area is less than 4500 cm, the glass plate can be easily handled and breakage of the glass plate during handling or processing can be suppressed. ２ More preferably, it is 4000 cm or less. ２ and even more preferably 3000 cm ２ It is particularly preferably 2000 cm ２ The following is the result.

[0060] When the glass 10 according to this embodiment is a glass plate, 25 cm ２The LTV (Local Thickness Variation) in the above range is preferably 2 μm or less. By having a flatness in this range, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and to obtain desired light-guiding characteristics. In particular, in a light guide, ghost phenomena and distortion due to differences in optical path length can be prevented. 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.

[0061] When the glass 10 according to this embodiment is formed into a circular glass plate having a diameter of 8 to 12 inches, the warpage is preferably 50 μm or less. If the warpage of this glass 10 is 50 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light guide characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage 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.

[0062] Furthermore, when the glass 10 according to this embodiment is formed into a circular glass plate with a diameter of 6 inches, the warpage is preferably 30 μm or less. If the warpage of this glass 10 is 30 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light-guiding characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage 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.

[0063] Furthermore, when the glass 10 according to this embodiment is a square glass plate with sides of 6 inches, the warpage is preferably 100 μm or less. If the warpage of this glass 10 is 100 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light-guiding characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage 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.

[0064] 2 is a cross-sectional view of a glass plate made from the glass according to this embodiment. When the glass 10 according to this embodiment is used as a glass plate G1, the "warpage" refers to a difference C between a maximum value B and a minimum value A of a perpendicular distance between a reference line G1D of the glass plate G1 and a center line G1C of the glass plate G1 in an arbitrary cross section that passes through the center of a main surface G1F of the glass plate G1 and is perpendicular to the main surface G1F of the glass plate G1.

[0065] The intersection line between the arbitrary orthogonal cross section and the main surface G1F of the glass sheet G1 is defined as a base line G1A. The intersection line between the arbitrary orthogonal cross section and the other main surface G1G of the glass sheet G1 is defined as an upper line G1B. Here, the center line G1C is a line connecting the centers of the glass sheet G1 in the thickness direction. The center line G1C is calculated by finding the midpoint between the base line G1A and the upper line G1B with respect to the direction of laser irradiation, which will be described later.

[0066] The reference line G1D is determined as follows. First, a base line G1A is calculated based on a measurement method that cancels the influence of the weight. A straight line is determined from the base line G1A using the least squares method. The determined straight line is the reference line G1D. A known method is used as the measurement method that cancels the influence of the weight.

[0067] For example, the main surface G1F of the glass plate G1 is supported at three points, a laser is irradiated onto the glass plate G1 using a laser displacement meter, and the height of the main surface G1F and the other main surface G1G of the glass plate G1 from an arbitrary reference plane is measured.

[0068] Next, the glass sheet G1 is inverted, and three points on the other main surface G1G opposite to the three points where the one main surface G1F was supported are supported, and the heights of the main surface G1F and the other main surface G1G of the glass sheet G1 from an arbitrary reference plane are measured. The influence of the glass sheet's own weight is canceled out by averaging 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 sheet G1, the height of the other main surface G1G is measured at a position corresponding to the measurement points on the main surface G1F. Similarly, before inversion, the height of the other main surface G1G is measured. After inverting the glass sheet G1, the height of the main surface G1F is measured at a position corresponding to the measurement points on the other main surface G1G. The warpage is measured, for example, using a laser displacement meter.

[0069] Furthermore, in the glass 10 according to this embodiment, the surface roughness Ra of the main surface is preferably 2 nm or less. Having an Ra in this range allows for the formation of a nanostructure of a desired shape on the main surface using imprinting technology or the like, and also allows for the attainment of desired light-guiding characteristics. In particular, in a light guide, diffuse reflection at the interface is suppressed, 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 defined in JIS B0601 (2001). In this specification, the surface roughness Ra is a value measured over an area of ​​10 μm × 10 μm using an atomic force microscope (AFM).

[0070] (Method for Producing Glass) The method for producing the glass 10 according to this embodiment is not particularly limited, but a preferred method for producing the glass 10 will be described below.

[0071] This embodiment includes the steps of preparing raw materials for the glass 10, melting the raw materials, and cooling the molten raw materials to obtain the glass 10. This manufacturing method can be used with existing methods for manufacturing flat glass. For example, known methods such as the float method, the fusion method, and the roll-out method can be used.

[0072] The raw materials for glass 10 are selected according to the composition of glass 10 to be obtained and mixed at a compounding ratio according to the composition of glass 10 to be obtained. In this embodiment, the ratio of Fe contained in the raw materials to the total amount of the raw materials (Fe / total raw materials), in terms of mass ratio, is preferably 0 ppm or more, more preferably 0.2 ppm or more, more preferably 0.5 ppm or more, more preferably 0.8 ppm or more, more preferably 1.0 ppm or more, and even more preferably 1.5 ppm or more. The ratio of Fe contained in the raw materials to the total amount of the raw materials (Fe / total raw materials), in terms of mass ratio, is preferably 15.0 ppm or less, more preferably 10.0 ppm or less, more preferably 7.0 ppm or less, more preferably 5.0 ppm or less, more preferably 4.0 ppm or less, and even more preferably 3.0 ppm or less. In terms of mass ratio, the ratio of Fe contained in the raw materials to the total amount of raw materials (Fe / total raw materials) is preferably 0 ppm to 15.0 ppm, more preferably 0.2 ppm to 10.0 ppm, more preferably 0.5 ppm to 7.0 ppm, more preferably 0.8 ppm to 5.0 ppm, more preferably 1.0 ppm to 4.0 ppm, and even more preferably 1.5 ppm to 3.0 ppm. This allows the Fe content of the glass 10 to be reduced. Here, Fe does not only refer to the Fe element contained in the raw materials, but may also include Fe element metals and compounds. The Fe content can be measured by ICP mass spectrometry. As a measuring instrument, for example, an Agilent 8800 manufactured by Agilent Technologies can be used.

[0073] In the step of melting the raw materials, the raw materials are placed in a container such as a crucible, and the raw materials placed in the container are heated to melt the raw materials. Any material may be used as the container, but in this embodiment, a container containing Pt is used. The heating temperature when melting the raw materials is preferably 950°C or higher, more preferably 1000°C or higher, more preferably 1050°C or higher, more preferably 1100°C or higher, and even more preferably 1120°C or higher. The heating temperature when melting the raw materials is preferably 1600°C or lower, more preferably 1500°C or lower, more preferably 1400°C or lower, more preferably 1350°C or lower, and even more preferably 1300°C or lower. The heating temperature when melting the raw materials is preferably 950° C. or higher and 1600° C. or lower, more preferably 1000° C. or higher and 1500° C. or lower, more preferably 1050° C. or higher and 1400° C. or lower, more preferably 1100° C. or higher and 1350° C. or lower, and even more preferably 1120° C. or higher and 1300° C. By setting the heating temperature within this range, dissolution of Pt contained in the container and Fe contained in the raw materials, etc. can be suppressed, and the Pt and Fe contents of glass 10 can be reduced.

[0074] (Effects) As described above, the glass 10 according to the first aspect of the present disclosure has La ２ O ３ , and B ２ O ３ and the refractive index n ｄ is 2.0100 or more, and Bi is ２ O ３ and B ２ O ３ The total content of Pt and Fe is less than 80%, the total content of Pt and Fe is 0.5 ppm or more and 15.0 ppm or less by mass ratio, and the parameter A defined by the formula (1) is 0.870 or more.

[0075] The present inventor is La ２ O ３ and B ２ O ３ Including Bi ２ O ３ and B ２ O ３The inventors have found that high-refractive-index glasses in which the total content of Pt and Fe is less than 80% tend to have low transmittance. The inventors have also found that high-refractive-index glasses tend to have high melting temperatures, which increases the amount of Pt and Fe dissolved during the manufacturing process, resulting in high Pt and Fe contents in the manufactured glass. High Pt and Fe contents make Pt and Fe more likely to precipitate as defects. In response to this, the inventors have found, through extensive research, that by setting the total content of Pt and Fe to 0.5 ppm or more and 15 ppm or less and setting parameter A to 0.880 or more, it is possible to suppress the precipitation of Pt and Fe as defects while also suppressing a decrease in transmittance. In other words, by satisfying the above conditions, the glass of the present disclosure can appropriately maintain a balance between the amounts of Pt and Fe, transmittance, and manufacturing conditions, thereby achieving a high refractive index and high transmittance while suppressing the precipitation of defects.

[0076] Glass 10 according to the second aspect of the present disclosure is glass 10 according to the first aspect, and is preferably glass 10 in which parameter B defined by formula (2) is 2.075 or greater. Glass 10 according to the present disclosure can maintain a high transmittance for visible light even when it has a high refractive index.

[0077] Glass 10 according to a third aspect of the present disclosure is glass 10 according to the first or second aspect, and preferably has a devitrification temperature of 1250° C. or less. Since glass 10 according to the present disclosure has a devitrification temperature of 1250° C. or less, the temperature at which raw materials are melted during the production of glass 10 can be made relatively low, and the contents of Pt and Fe can be made low.

[0078] Glass 10 according to a fourth aspect of the present disclosure is glass 10 according to any one of the first to third aspects, and preferably has a Young's modulus of 90 GPa or greater. Glass 10 according to the present disclosure having a Young's modulus of 90 GPa or greater can appropriately suppress breakage.

[0079] Glass 10 according to a fifth aspect of the present disclosure is glass 10 according to any one of the first to fourth aspects, wherein the ratio of the content of trivalent Ti to the total content of Ti, by mass ratio, is preferably less than 0.1000, thereby making it possible to appropriately achieve a high refractive index and a high transmittance.

[0080] Glass 10 according to a sixth aspect of the present disclosure is glass 10 according to any one of the first to fifth aspects, and preferably does not contain Sb, thereby making it possible to appropriately achieve a high refractive index and high transmittance.

[0081] Glass 10 according to a seventh aspect of the present disclosure is glass 10 according to any one of the first to sixth aspects, wherein, in mol % on an oxide basis, ２ : 0% or more and 20.0% or less, B ２ O ３ :0% or more and 30.0% or less, Y ２ O ３ : 0% or more and 10.0% or less, BaO: 0% or more and 10.0% or less, Bi ２ O ３ :0% or more and 30.0% or less, Gd ２ O ３ :0% or more and 10.0% or less, Nb ２ O ５ : 0% or more and 10.0% or less, ZnO: 0% or more and 20.0% or less, WO ３ : 0% or more and less than 30.0%, Ta ２ O ５ :0% or more and 10.0% or less, P ２ O ５ :0% or more and 30.0% or less, ZrO ２ :0% or more and 15.0% or less, TiO ２ :0% or more and 40.0% or less, La ２ O ３ : 0% or more and 40.0% or less, whereby a high refractive index and a high transmittance can be appropriately achieved.

[0082] Glass 10 according to an eighth aspect of the present disclosure is glass 10 according to any one of the first to seventh aspects, wherein the specific gravity is 6.20 g / cm ３The following are preferred: Such a low specific gravity makes the glass 10 easy to handle.

[0083] The glass 10 according to a ninth aspect of the present disclosure is the glass 10 according to any one of the first to eighth aspects, and is preferably used as a light guide plate. The glass 10 according to the present disclosure can be suitably used for a light guide plate.

[0084] A method for producing glass according to a tenth aspect of the present disclosure includes heating raw materials at a temperature of 950°C or higher and 1600°C or lower to melt the raw materials, and cooling the melted raw materials to obtain glass 10 according to any of the first to ninth aspects. According to the present disclosure, by setting the heating temperature of the raw materials within the above range, it is possible to produce glass with low Pt and Fe contents, which has a high refractive index and high transmittance while suppressing the precipitation of defects.

[0085] Examples Next, examples will be described. Tables 1 and 2 show the glasses of the examples. The embodiments may be modified as long as the effects of the invention are achieved.

[0086]

[0087] Example 1 In Example 1, glass having a thickness of 10 mm and 1 mm was produced with the composition shown in Table 1. Specifically, the raw materials having the composition shown in Table 1 were uniformly mixed and melted in a platinum crucible at 1300°C for 2 hours to obtain a uniform molten glass. Next, the molten glass was poured into a carbon mold having dimensions of 60 mm x 50 mm x 30 mm. After holding at 660°C for 1 hour, the mold was cooled to room temperature at a rate of approximately 1°C / min to obtain a glass block. Next, the glass block was cut into a size of 30 mm x 30 mm using a cutting machine (a small cutting machine manufactured by Marutoh Co., Ltd.), and the thickness was adjusted and the surface was polished using a grinding machine (SGM-6301 manufactured by Hidewa Kogyo Co., Ltd.) and a single-sided polishing machine (EJ-380IN manufactured by Engis Japan Co., Ltd.), producing glass having dimensions of 30 mm x 30 mm and a thickness of 10 mm and 1 mm.

[0088] The total content of Pt and Fe in the glass of Example 1 was measured. The measurement method was the same as that described in the above embodiment.３＋ The refractive index n of the glass of Example 1 was measured. ｄ , transmittance τ ４４０ , transmittance τ ４６０ , wavelength λ ５ , Young's modulus E, specific gravity d, Abbe number v ｄ The devitrification temperature was measured using the method described in the above embodiment. The measurement results are shown in Table 1.

[0089] In Examples 2 to 73, glasses were produced in the same manner as in Example 1, except that the compositions were those shown in Table 1 or Table 2. The measurement results for the glasses of each example are shown in Table 1.

[0090] (Evaluation) The glasses of each example were evaluated for optical properties and defect deposition.

[0091] In evaluating optical properties, transmittance τ ４４０ is 0.840 or more, and the refractive index n ｄ When the value of the defect deposition was 2.0100 or more, it was rated as ◯, and when at least one of these values ​​was not satisfied, it was rated as ×. In the evaluation of defect deposition, when no defects were visually observed, it was rated as ◯, and when defects were observed, it was rated as ×.

[0092] As shown in Table 1, in Examples 72 and 73, which are comparative examples, at least one of the evaluations of optical properties and defect deposition was ×, indicating that it was not possible to achieve a high refractive index and high transmittance while suppressing defect deposition. In Examples 1 to 71, which are working examples, both the evaluations of optical properties and defect deposition were ◯, indicating that it was possible to achieve a high refractive index and high transmittance while suppressing defect deposition.

[0093] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described 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 above-described embodiments.

[0094] 10. Glass

Claims

1. La ２ O ３ , and B ２ O ３ Including the refractive index n ｄ is 2.0100 or more, and Bi is ２ O ３ and B ２ O ３ A glass having a total content of Pt and Fe of less than 80%, a total content of Pt and Fe of 0.5 ppm or more and 15.0 ppm or less in mass ratio, and a parameter A defined by formula (1) of 0.870 or more. ４４０ + 0.005 × (Pt + Fe) ... (1) where, τ ４４０ is the internal transmittance for light with a wavelength of 440 nm when converted into a thickness of 10 mm, and (Pt+Fe) is the total content (ppm) of Pt and Fe in mass ratio.

2. The glass according to claim 1, wherein the parameter B defined by the formula (2) is 2.075 or more. ４６０ + 0.583 x n ｄ ... (2) Here, τ ４６０ is the internal transmittance for light with a wavelength of 460 nm when converted into a thickness of 10 mm.

3. The glass according to claim 1 or 2, having a devitrification temperature of 1250°C or lower.

4. The glass according to claim 1 or 2, having a Young's modulus of 90 GPa or more.

5. The glass according to claim 1 or 2, wherein the ratio of the trivalent Ti content to the total Ti content, in terms of mass ratio, is less than 0.

100.

6. The glass according to claim 1 or 2, which does not contain Sb.

7. In terms of mole percent based on oxide, SiO ２ : 0% or more and 20.0% or less, B ２ O ３ :0% or more and 30.0% or less, Y ２ O ３ : 0% or more and 10.0% or less, BaO: 0% or more and 10.0% or less, Bi ２ O ３ :0% or more and 30.0% or less, Gd ２ O ３ :0% or more and 10.0% or less, Nb ２ O ５ : 0% or more and 10.0% or less, ZnO: 0% or more and 20.0% or less, WO ３ : 0% or more and less than 30.0%, Ta ２ O ５ :0% or more and 10.0% or less, P ２ O ５ :0% or more and 30.0% or less, ZrO ２ :0% or more and 15.0% or less, TiO ２ :0% or more and 40.0% or less, La ２ O ３ The glass according to claim 1 or 2, comprising:

8. Specific gravity is 6.20 g / cm ３ 3. The glass of claim 1 or claim 2, wherein:

9. The glass according to claim 1 or 2, which is used as a light guide plate.

10. A method for producing glass, comprising: heating raw materials at 950° C. or higher and 1,600° C. or lower to melt the raw materials; and cooling the molten raw materials to obtain the glass according to claim 1 or 2.

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