Glass and method for producing glass

Abstract

The present invention suppresses a decrease in chemical resistance while achieving a high refractive index and a high transmittance. A glass (10) contains, in mol% based on oxides, 1.0% to 60% inclusive of Bi2O3 and 0.001 ppm to 1.0% inclusive of HfO2, and a parameter (A) expressed by formula (1) is 2 ppm or more and less than 30 ppm.

Description

Glass and method for manufacturing glass

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

[0002] In recent years, there has been a demand for high refractive index glass, and Bi ２ O ３ Glass containing Bi is known. ２ O ３ Since it easily reacts with Pt, Bi ２ O ３ When producing glass containing Pt, materials other than Pt may be used in the melting furnace. For example, Patent Document 1 describes the use of a non-metallic crucible, and Patent Document 2 describes the use of a heat-resistant container made of Au or an alloy of Au and a noble metal.

[0003] JP 2007-70156 A JP 2004-18312 A

[0004] However, Bi ２ O ３ Glasses with high refractive indexes containing fluorine may have low transmittance and reduced chemical resistance, so there is a demand for glass that has a high refractive index and high transmittance while suppressing the reduction in chemical resistance.

[0005] An object of the present invention is to provide a glass that can have a high refractive index and high transmittance while suppressing a decrease in chemical resistance, and a method for producing the glass.

[0006] The glass according to the present disclosure contains, in mole percent on an oxide basis, Bi ２ O ３ 1.0% or more and 60% or less, HfO ２ The content is 0.001 ppm or more and 1.0% or less, and a parameter A shown in the following formula (1) is 2 ppm or more and less than 30 ppm.

[0007] A = Au [ppm] + 10 × Pt [ppm] (1) Here, Au [ppm] refers to the ratio (ppm) of the amount of Au contained in the glass to the entire glass, in mass ratio, and Pt [ppm] refers to the ratio (ppm) of the amount of Pt contained in the glass to the entire glass, in mass ratio.

[0008] The method for producing glass according to the present disclosure includes: charging glass raw materials into a melting furnace formed of an Au alloy having an Au content of 95% or more in mol %, melting the glass raw materials in the melting furnace, and cooling the molten glass raw materials to produce a glass having a Bi content of 95% or more in mol % on an oxide basis. ２ O ３ 1.0% or more and 60% or less, HfO ２ and obtaining a glass containing 0.001 ppm or more and 1.0% or less of the above, in which parameter A shown in the following formula (1) is less than 30 ppm.

[0009] A = Au [ppm] + 10 × Pt [ppm] (1) Here, Au [ppm] refers to the ratio (ppm) of the amount of Au contained in the glass to the entire glass, in mass ratio, and Pt [ppm] refers to the ratio (ppm) of the amount of Pt contained in the glass to the entire glass, in mass ratio.

[0010] According to the present invention, it is possible to suppress a decrease in chemical resistance while achieving a high refractive index and high transmittance.

[0011] Fig. 1 is a schematic diagram of glass according to the present embodiment. Fig. 2 is a cross-sectional view of the glass according to the present embodiment in the form of a glass plate. Fig. 3 is a schematic diagram of melting equipment according to the present embodiment.

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 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 hereinafter.

[0013] (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.

[0014] (Glass Composition) The composition of the glass 10 will be described below.

[0015] (Bi ２ O ３ ) Glass 10 is Bi ２ O ３ Glass 10 contains, in mole percent on an oxide basis, Bi. ２ O ３ The content of Bi is 1.0% or more and 60% or less, preferably 10% or more and 50% or less, more preferably 21% or more and 43% or less, more preferably 23% or more and 40% or less, and even more preferably 25% or more and 38% or less. ２ O ３ It is also preferable that the content of Bi is 20.8% or more and 28.4% or less. ２ O ３ When the content falls within this range, a high refractive index can be appropriately achieved.

[0016] (HfO ２ ) Glass 10 is HfO ２ Glass 10 contains, in mole percent on an oxide basis, HfO ２ The content of HfO is 0.001 ppm or more and 1.0% or less, preferably 0.003 ppm or more and 0.5% or less, more preferably 0.010 ppm or more and 0.2% or less, more preferably 0.10 ppm or more and 0.1% or less, and even more preferably 1.0 ppm or more and 0.08% or less. ２When the lower limit of the content of HfO is within this range, the deterioration of chemical resistance can be suppressed. ２ When the upper limit of the content of HfO is within this range, devitrification can be suppressed. ２ The content of can be measured by laser ablation ICP mass spectrometry in addition to the ICP mass spectrometry described below. As a measuring instrument, for example, Jupiter manufactured by Thermo Fisher Scientific can be used.

[0017] (Pt and Au) The glass 10 has a parameter A defined by the following formula (1) of less than 30 ppm.

[0018] A=Au[ppm]+10×Pt[ppm]...(1)

[0019] In formula (1), Au [ppm] refers to the ratio (ppm) of the amount of Au contained in glass 10 to the entire amount of glass 10, in terms of mass ratio. Furthermore, Pt [ppm] in formula (1) refers to the ratio (ppm) of the amount of Pt contained in glass 10 to the entire amount of glass 10, in terms of mass ratio.

[0020] When the parameter A is in the above range, Bi ２ O ３ This can suppress a decrease in the transmittance of the high-refractive-index glass 10 containing the compound (I), thereby achieving high transmittance. Parameter A is preferably 0 ppm or more and less than 30 ppm, more preferably 1 ppm or more and less than 30 ppm, more preferably 2 ppm or more and less than 30 ppm, more preferably 3 ppm or more and 26 ppm or less, more preferably 3 ppm or more and 25 ppm or less, more preferably 6 ppm or more and 23 ppm or less, more preferably 8 ppm or more and 20 ppm or less, and more preferably 11 ppm or more and 19 ppm or less. By setting parameter A within this range, the glass 10 can have high transmittance.

[0021] Here, Pt and Au do not refer only to the Pt and Au elemental metals contained in the glass 10, but may also include the Pt and Au elemental metals and compounds. In other words, the total content of Pt and Au can be said to include the content of the Pt and Au elemental metals and the content of Pt and Au ions in the compounds. The Pt and Au 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, sulfuric acid, hydrochloric acid, and nitric 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] (Preferred Composition) The preferred composition of the glass 10 will be described in detail below.

[0024] (TeO ２ ) Glass 10 is TeO ２ The glass 10 preferably contains, in mole percent on an oxide basis, TeO ２ The content of TeO is preferably 1.0% or more and 60% or less, more preferably 2.0% or more and 40% or less, even more preferably 2.0% or more and 30% or less, and still more preferably 3.0% or more and 27% or less. ２ When the content falls within this range, a lower liquidus temperature and a high refractive index of the glass 10 can be appropriately achieved.

[0025] (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 ５The content of Nb is preferably 0% or more and 15% or less, more preferably 0% or more and 10% or less, even more preferably 2.0% or more and 10% or less, even more preferably 3.0% or more and 9.0% or less, and even more preferably 4.0% or more and 8.0% or less. ２ O ５ When the content falls within this range, the refractive index and devitrification resistance of the glass can be appropriately improved.

[0026] (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 SiO is preferably 0% or more and 20% or less, more preferably 1.0% or more and 15% or less, even more preferably 3.0% or more and 13% or less, and even more preferably 5.0% or more and 11% or less. ２ It is also preferable that the content of SiO is 0% or more and 10% 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.

[0027] (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 and 15% or less, more preferably 0.5% or more and 10% or less, even more preferably 1.0% or more and 7.0% or less, and even more preferably 2.0% or more and 5.0% 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.

[0028] (B ２ O ５ ) Glass 10 is B ２ O ５ The glass 10 preferably contains, in mole percent on an oxide basis, B２ O ５ The content of B is preferably 1.0% or more and 50% or less, more preferably 10% or more and 40% or less, even more preferably 15% or more and 35% or less, and even more preferably 20% or more and 30% 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.

[0029] (P ２ O ５ ) Glass 10 is P ２ O ５ The glass 10 preferably contains, in mole percent on an oxide basis, P. ２ O ５ The content of P is preferably 0% or more and 25% or less, more preferably 1.0% or more and 20% or less, even more preferably 5.0% or more and 15% or less, and even more preferably 7.0% or more and 13% 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.

[0030] (Li ２ O) Glass 10 is Li ２ The glass 10 preferably contains, in mole percent on an oxide basis, Li ２ The O content is preferably 0% or more and 15% or less, more preferably 1.0% or more and 12% or less, even more preferably 3.0% or more and 10% or less, and even more preferably 5.0% or more and 9.0% or less. ２ When the O content falls within this range, the transmittance and devitrification resistance of the glass can be appropriately improved.

[0031] (Na ２ O) Glass 10 is Na ２ It is preferable that the glass 10 contains, in mole percent on an oxide basis, Na ２The O content is preferably 0% or more and 10% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.2% or more and 2.0% or less, and even more preferably 0.5% or more and 1.0% or less. ２ When the O content falls within this range, the transmittance and devitrification resistance of the glass can be appropriately improved.

[0032] (K ２ O) Glass 10 is K ２ It is preferable that the glass 10 contains, in mole percent on an oxide basis, K. ２ The O content is preferably 0% or more and 10% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.2% or more and 2.0% or less, and even more preferably 0.5% or more and 1.0% or less. ２ When the O content falls within this range, the transmittance and devitrification resistance of the glass can be appropriately improved.

[0033] (SrO) Glass 10 preferably contains SrO. The SrO content of glass 10, expressed in mole percent on an oxide basis, is preferably 0% to 10%, more preferably 0.5% to 5.0%, even more preferably 1.0% to 3.0%, and still more preferably 1.5% to 2.0%. When the SrO content is within this range, the refractive index, devitrification resistance, and visible light transmittance of the glass are improved.

[0034] (BaO) Glass 10 preferably contains BaO. The BaO content of glass 10, expressed in mole percent on an oxide basis, is preferably 0% to 10%, more preferably 0.5% to 5.0%, even more preferably 1.0% to 3.0%, and still more preferably 1.5% to 2.0%. When the BaO content falls within this range, the refractive index, devitrification resistance, and visible light transmittance of the glass are improved.

[0035] (TiO ２ ) Glass 10 is TiO ２ The glass 10 preferably contains, in mole percent on an oxide basis, TiO２ The content of TiO is preferably 0% or more and 10% or less, more preferably 0.5% or more and 5.0% or less, even more preferably 1.0% or more and 3.0% or less, and even more preferably 1.5% or more and 2.0% or less. ２ When the content falls within this range, the refractive index and chemical durability of the glass are improved.

[0036] (Ta ２ O ５ ) The glass 10 is Ta ２ O ５ The glass 10 preferably contains, in mole percent on an oxide basis, Ta. ２ O ５ The content of Ta is preferably 0% or more and 10% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.2% or more and 2.0% or less, and still more preferably 0.5% or more and 1.0% 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.

[0037] (W.O. ３ ) Glass 10 is WO ３ The glass 10 preferably contains, in mole percent on an oxide basis, WO ３ The content of WO is preferably 0% or more and 10% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.2% 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, the transmittance and devitrification resistance of the glass can be appropriately improved.

[0038] (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% to 30%, more preferably 1.0% to 20%, even more preferably 3.0% to 15%, and still more preferably 5.0% to 12%. When the ZnO content is within this range, the liquidus temperature of the glass is lowered, thereby suppressing the precipitation of defects.

[0039] (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 and 10% or less, more preferably 0.5% or more and 5.0% or less, even more preferably 1.0% or more and 3.0% or less, and even more preferably 1.5% or more and 2.0% or less. ２ O ３ When the content falls within this range, a high refractive index and improved chemical durability can be appropriately achieved.

[0040] (HfO ２ / ZrO ２ Glass 10 contains, in mole percent based on oxide, ZrO ２ HfO content ２ The ratio of the content of HfO ２ / ZrO ２ ) is preferably 0.000 or more and 0.040 or less, more preferably 0.005 or more and 0.030 or less, even more preferably 0.010 or more and 0.025 or less, and even more preferably 0.015 or more and 0.023 or less. ２ HfO content ２ When the content ratio falls within this range, improvements in chemical resistance and devitrification resistance can be appropriately realized.

[0041] (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.

[0042] (TeO２ + ZrO ２ Glass 10 contains TeO in mole percent based on oxides. ２ and ZrO ２ The total content of TeO ２ + ZrO ２ is preferably 0.20% or more and 40.0% or less, more preferably 0.50% or more and 35.0% or less, still more preferably 1.00% or more and 30.0% or less, still more preferably 3.0% or more and 29.0% or less, and still more preferably 5.0% or more and 28.0% or less. ２ + ZrO ２ It is also preferable that TeO is 3.0% or more and 40.0% or less. ２ and ZrO ２ The total content of TeO ２ + ZrO ２ When the refractive index falls within this range, improvements in the refractive index and chemical resistance can be appropriately achieved.

[0043] (Glass Characteristics) The characteristics of the glass 10 will be described below.

[0044] (Number of Bubbles) The number of bubbles with a diameter of 30 μm or more per 100 mL of glass 10 is preferably less than 100, more preferably less than 50, and even more preferably less than 10. This reduces internal defects in glass 10 and improves optical properties. The number of bubbles with a diameter of 30 μm or more per 100 mL of glass 10 can be measured in accordance with the "JOGIS 12:2019 Method for Measuring Bubbles in Optical Glass" standard of the Japan Optical Glass Industry Association. The number of bubbles is measured using a microscope capable of reading at least 2 μm or an equivalent device.

[0045] (Refractive index n ｄ ) Refractive index n of glass 10 ｄ The refractive index n is preferably 2.00000 or more and 2.20000 or less, more preferably 2.03000 or more and 2.15000 or less, more preferably 2.05000 or more and 2.13000 or less, and even more preferably 2.07000 or more and 2.12000 or less. ｄWhen 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.

[0046] (Transmittance τ ４４０ ) Transmittance τ of glass 10 ４４０ is preferably 30% or more and 100% or less, more preferably 50% or more and 98% or less, more preferably 80% or more and 97% or less, and even more preferably 90% or more and 96% or less. ４４０ When the transmittance τ is in this range, visible light can be transmitted appropriately. ４４０ is the internal transmittance for light with a wavelength of 440 nm when converted into a thickness of 10 mm.

[0047] 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.

[0048]

[0049] (Abbe number v ｄ ) Abbe number v of glass 10 ｄ is preferably 15.00 or more and 35.00 or less, more preferably 16.00 or more and 30.00 or less, more preferably 17.00 or more and 25.00 or less, and even more preferably 18 or more and 20.00 or less. ｄ is a value that represents the properties related to dispersion. ｄ can be measured by the V-block method.

[0050] (Devitrification Temperature) The devitrification temperature of the glass 10 is preferably 700°C or higher and 900°C or lower, more preferably 720°C or higher and 870°C or lower, more preferably 740°C or higher and 850°C or lower, and even more preferably 760°C or higher and 830°C or lower. When the devitrification temperature is within this range, improvement in devitrification resistance can be appropriately achieved. The devitrification temperature can be measured by the following method. A sample glass was crushed to obtain glass particles that passed through a 4 mm sieve and remained on a 2 mm sieve. These 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°C to 1400°C in 10°C increments for 1 hour. The glass particles were then allowed to cool naturally, and the presence or absence of crystal precipitation was observed under a microscope. The lowest temperature at which crystals with a long side or major axis of 1 μm or higher were not observed was determined as the devitrification temperature.

[0051] (Young's Modulus E) The Young's modulus E of the glass 10 is preferably 66 GPa or more, more preferably 67 GPa or more and 90 GPa or less, and even more preferably 68 GPa or more and 80 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.

[0052] (Specific Gravity d) The specific gravity d of the glass 10 is preferably 3.50 or more and 8.0 or less, more preferably 4.0 or more and 7.5 or less, even more preferably 4.5 or more and 7.0 or less, and even more preferably 5.0 or more and 6.8 or less. Such a low specific gravity makes the glass 10 easy to handle. The specific gravity d can be measured by the Archimedes method.

[0053] (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.

[0054] 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 8 cm 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.

[0055] 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.

[0056] When the glass 10 according to this embodiment is formed into a circular glass plate having a diameter of 8 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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).

[0065] (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.

[0066] In this embodiment, the method includes the steps of charging glass frits, which are the raw materials for glass 10, into a melting furnace 30, melting the glass frits in the melting furnace 30, and cooling the molten glass frits to obtain glass 10. In this manufacturing method, an existing flat glass manufacturing method can be used. For example, known methods such as a float method, a fusion method, and a roll-out method can be used.

[0067] (Step of charging glass raw materials into melting furnace) The types of glass raw materials are selected according to the composition of the glass 10 to be obtained, and are mixed at a compounding ratio according to the composition of the glass 10 to be obtained.

[0068] (Step of Melting Glass Raw Materials) Fig. 3 is a schematic diagram of a melting facility according to this embodiment. In this embodiment, glass raw materials are melted using a melting facility 20. As shown in Fig. 3, the melting facility 20 includes a melting furnace 30. The melting furnace 30 is a container (furnace) into which glass raw materials are charged.

[0069] (Melting Furnace) The melting furnace 30 is preferably formed of an Au alloy. The Au alloy refers to an alloy having an Au content of 95% or more in mole percent. This suppresses the elution of Pt and Au from the melting furnace 30, thereby suppressing the Pt and Au contents in the glass 10 and suppressing a decrease in the transmittance of the glass 10.

[0070] (Melting Conditions) In the present embodiment, glass frits are charged into the melting furnace 30 described above, and the inside of the melting furnace 30 is heated, thereby melting the glass frits in the melting furnace 30. By setting the melting conditions in this manner, the glass frits can be appropriately melted, and the glass 10 can be appropriately produced.

[0071] (Step of Obtaining Glass) In this embodiment, glass raw materials melted in the melting furnace 30 are cooled to obtain the glass 10 .

[0072] (Effects) As described above, the glass 10 according to the first aspect of the present disclosure contains, in mole percent on an oxide basis, Bi. ２ O ３ 1.0% or more and 60% or less, HfO ２ The parameter A shown in formula (1) is 2 ppm or more and less than 30 ppm. ２ O ３ When the content is in this range, a high refractive index can be appropriately realized, and when the parameter A is less than 30 ppm, Bi ２ O ３ The decrease in the transmittance of the high refractive index glass 10 containing HfO can be suppressed, thereby achieving high transmittance. ２ When the content falls within this range, a decrease in chemical resistance can be suppressed.

[0073] Glass 10 according to the second aspect of the present disclosure is glass 10 according to the first aspect, and preferably has parameter A of 3 ppm or more and 26 ppm or less, thereby more appropriately suppressing a decrease in the transmittance of glass 10, which has a high refractive index.

[0074] Glass 10 according to a third aspect of the present disclosure is glass 10 according to the first or second aspect, and preferably has less than 100 bubbles with a diameter of 30 μm or more per 100 mL. This reduces defects in glass 10, enabling the optical properties of glass 10 to be improved.

[0075] Glass 10 according to a fourth aspect of the present disclosure is glass 10 according to any one of the first to third aspects, wherein, in mol % on an oxide basis, TeO ２ 1.0% or more and 60% or less, Nb ２ O ５ 0% or more and 10% or less, SiO ２ 0% or more and 10% or less, ZrO ２ 0% or more and 15% or less, B ２ O ５ is 1.0% or more and 50% or less, P ２ O ５ 0% or more and 25% or less, Li ２ O is 0% or more and 15% or less, Na ２ O is 0% or more and 10% or less, K is ２ O is 0% or more and 10% or less, SrO is 0% or more and 10% or less, BaO is 0% or more and 10% or less, TiO ２ is 0% or more and 10% or less, Ta ２ O ５ 0% or more and 10% or less, WO ３ ZnO is 0% or more and 10% or less, La is 0% or more and 30% or less ２ O ３ Contains 0% or more and 10% or less of ZrO ２ HfO content ２ It is preferable that the ratio of the content of Sb to the content of Hb is 0.005 or more and 0.03 or less, and Sb is not contained. This makes it possible to appropriately improve the refractive index, transmittance, and chemical resistance.

[0076] Glass 10 according to a fifth aspect of the present disclosure is glass 10 according to any one of the first to fourth aspects, further comprising TeO ２ and ZrO ２ The total content of TeO ２ + ZrO ２ is preferably 3% or more and 40% or less, whereby the refractive index, transmittance, and chemical resistance can be appropriately improved.

[0077] 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 has a Young's modulus of 66 GPa or greater. This makes it possible to suppress breakage of glass 10.

[0078] Glass 10 according to a seventh aspect of the present disclosure is the glass 10 according to any one of the first to sixth aspects, and is preferably used as a light guide plate. Glass 10 according to the present disclosure can be suitably used as a light guide plate.

[0079] A method for producing glass according to an eighth aspect of the present disclosure includes: charging glass raw materials into a melting furnace 30 formed of an Au alloy having an Au content of 95% or more in mol %, melting the glass raw materials in the melting furnace, and cooling the molten glass raw materials to produce a glass having a Bi content of 95% or more in mol % on an oxide basis. ２ O ３ 1.0% or more and 60% or less, HfO ２ and obtaining glass 10 containing 0.001 ppm or more and 1.0% or less of the above compound, and having parameter A shown in formula (1) of less than 30 ppm. According to the present disclosure, the refractive index, transmittance, and chemical resistance can be appropriately improved.

[0080] The method for producing glass according to a ninth aspect of the present disclosure is the method according to the eighth aspect, wherein parameter A is preferably 3 ppm or more and 26 ppm or less, thereby more appropriately suppressing the decrease in transmittance of high-refractive-index glass 10.

[0081] A glass manufacturing method according to a tenth aspect of the present disclosure is the manufacturing method according to the eighth or ninth aspect, wherein the number of bubbles with a diameter of 30 μm or more per 100 mL of glass 10 is preferably less than 100. This reduces defects in glass 10, and improves the optical properties of glass 10.

[0082] A method for producing glass according to an eleventh aspect of the present disclosure is the method according to any one of the eighth to tenth aspects, wherein the glass 10 contains, in mole percent on an oxide basis, TeO ２ 1.0% or more and 60% or less, Nb ２ O ５ 0% or more and 10% or less, SiO２ 0% or more and 10% or less, ZrO ２ 0% or more and 15% or less, B ２ O ５ is 1.0% or more and 50% or less, P ２ O ５ 0% or more and 25% or less, Li ２ O is 0% or more and 15% or less, Na ２ O is 0% or more and 10% or less, K is ２ O is 0% or more and 10% or less, SrO is 0% or more and 10% or less, BaO is 0% or more and 10% or less, TiO ２ is 0% or more and 10% or less, Ta ２ O ５ 0% or more and 10% or less, WO ３ ZnO is 0% or more and 10% or less, La is 0% or more and 30% or less ２ O ３ Contains 0% or more and 10% or less of ZrO ２ HfO content ２ It is preferable that the ratio of the content of Sb to the content of Hb is 0.005 or more and 0.03 or less, and Sb is not contained. This makes it possible to appropriately improve the refractive index, transmittance, and chemical resistance.

[0083] A method for producing glass according to a twelfth aspect of the present disclosure is the method according to any one of the eighth to eleventh aspects, wherein the glass 10 contains TeO ２ and ZrO ２ The total content of TeO ２ + ZrO ２ is preferably 3% or more and 40% or less, whereby the refractive index, transmittance, and chemical resistance can be appropriately improved.

[0084] A glass manufacturing method according to a thirteenth aspect of the present disclosure is the manufacturing method according to any one of the eighth to twelfth aspects, wherein the glass 10 preferably has a Young's modulus of 66 GPa or more. This makes it possible to suppress breakage of the glass 10.

[0085] Examples Next, examples will be described. Tables 1 to 6 show the glasses of each example. Table 1 shows the glass compositions of Examples 1 to 23, Table 2 shows the evaluation results of Examples 1 to 23, Table 3 shows the glass compositions of Examples 24 to 46, Table 4 shows the evaluation results of Examples 24 to 46, Table 5 shows the glass compositions of Examples 47 to 70, and Table 6 shows the evaluation results of Examples 47 to 70. Note that 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, glass raw materials for obtaining the composition shown in Table 1 were uniformly mixed and melted in a melting furnace at 980°C for 2 hours to obtain a uniform molten glass. Next, the molten glass was poured into a carbon mold having a length x width x height 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 temperature decrease rate of approximately 1°C / min to obtain a glass block. Next, the glass block was cut into a length x width of 30 mm x 30 mm using a cutter (a small cutter manufactured by Marutoh Co., Ltd.), and the plate thickness was adjusted and the surface was polished using a grinder (SGM-6301 manufactured by Hidewa Kogyo Co., Ltd.) and a single-sided polisher (EJ-380IN manufactured by Engis Japan Co., Ltd.), producing glass having a length x width of 30 mm x 30 mm and a thickness of 10 mm and 1 mm.

[0088] The parameter A (Au [ppm] + 10 × Pt [ppm]) shown in formula (1) of the glass of Example 1 was measured. The measurement method was the same as that described in the above embodiment. The refractive index n ｄ , transmittance τ ４４０ , 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 2.

[0089] Examples 2 to 70 In Examples 2 to 70, glasses were produced and measured in the same manner as in Example 1, except that the compositions and production conditions were as shown in Tables 1 to 6.

[0090] (Evaluation) The glasses of each example were evaluated for optical properties, chemical resistance, and devitrification. Note that the evaluation of devitrification is an optional evaluation.

[0091] In evaluating optical properties, transmittance τ ４４０ is 70% or more, and the refractive index n ｄ If the transmittance τ is 2.04000 or more, it is marked as ◯, and if at least one of these is not satisfied, it is marked as ×. ４４０ is 90% or more, and the refractive index n ｄ A value of 2.07000 or more was rated as Excellent. In the evaluation of chemical resistance, a weight loss rate of less than 0.30% after the acid resistance test specified in JOGIS 06 was rated as Good, and a value of 0.30 or more was rated as Poor. In the evaluation of devitrification, a devitrification temperature of less than 880°C was rated as Good, and a value of 880°C or more was rated as Poor.

[0092] As shown in each table, in Examples 68 to 70, which are comparative examples, the optical properties were evaluated as ×, indicating that all of the refractive index, transmittance, and chemical resistance could not be appropriately improved. In Examples 1 to 67, which are working examples, the refractive index, transmittance, and chemical resistance were all evaluated as ◯, indicating that all of the refractive index, transmittance, and chemical resistance could be appropriately improved.

[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 30 Melting furnace

Claims

1. In terms of mole percent based on oxide, Bi ２ O ３ 1.0% or more and 60% or less, HfO ２ A glass containing 0.001 ppm or more and 1.0% or less of Au, and having a parameter A shown in the following formula (1) of 2 ppm or more and less than 30 ppm: A=Au[ppm]+10×Pt[ppm] (1) Here, Au[ppm] refers to the ratio (ppm) of the amount of Au contained in the glass to the entire glass in mass ratio, and Pt[ppm] refers to the ratio (ppm) of the amount of Pt contained in the glass to the entire glass in mass ratio.

2. The glass according to claim 1, wherein the parameter A is 3 ppm or more and 26 ppm or less.

3. The glass according to claim 1, wherein the number of bubbles having a diameter of 30 μm or more per 100 mL is less than 100.

4. In terms of mole percent based on oxide, TeO ２ 1.0% or more and 60% or less, Nb ２ O ５ 0% or more and 10% or less, SiO ２ 0% or more and 10% or less, ZrO ２ 0% or more and 15% or less, B ２ O ５ 1.0% or more and 50% or less, P ２ O ５ Li is 0% or more and 25% or less. ２ O: 0% to 15% ２ O is 0% or more and 10% or less, K ２ O is 0% or more and 10% or less, SrO is 0% or more and 10% or less, BaO is 0% or more and 10% or less, TiO ２ 0% or more and 10% or less, Ta ２ O ５ 0% to 10%; WO ３ ZnO is 0% or more and 10% or less, La is 0% or more and 30% or less, ２ O ３ Contains 0% or more and 10% or less of ZrO ２ HfO content ２ The glass according to claim 1 , wherein the ratio of the content of is 0.005 to 0.03, and the glass does not contain Sb.

5. TeO ２ Content and ZrO ２ The total content of TeO ２ + ZrO ２ The glass of claim 1 , wherein the content of C is greater than or equal to 3% and less than or equal to 40%.

6. The glass according to claim 1, having a Young's modulus of 66 GPa or more.

7. The glass according to any one of claims 1 to 6, which is used as a light guide plate.

8. A method of melting a glass raw material by feeding a glass raw material into a melting furnace formed of an Au alloy having a Au content of 95% or more in mole percent, melting the glass raw material in the melting furnace, and cooling the melted glass raw material to obtain a glass having a Bi content of 95% or more in mole percent based on oxides. ２ O ３ 1.0% or more and 60% or less, HfO ２ and obtaining a glass containing 0.001 ppm or more and 1.0% or less of Au and having a parameter A shown in the following formula (1) of less than 30 ppm: A=Au[ppm]+10×Pt[ppm] (1) where Au[ppm] refers to the ratio (ppm) of the amount of Au contained in the glass to the entire glass, in mass ratio, and Pt[ppm] refers to the ratio (ppm) of the amount of Pt contained in the glass to the entire glass, in mass ratio.

9. The method for producing glass according to claim 8, wherein the parameter A is 3 ppm or more and 26 ppm or less.

10. The method for producing glass according to claim 8, wherein the number of bubbles having a diameter of 30 μm or more per 100 mL of the glass is less than 100.

11. The glass contains, in mole percent on an oxide basis, TeO ２ 1.0% or more and 60% or less, Nb ２ O ５ 0% or more and 10% or less, SiO ２ 0% or more and 10% or less, ZrO ２ 0% or more and 15% or less, B ２ O ５ 1.0% or more and 50% or less, P ２ O ５ Li is 0% or more and 25% or less. ２ O: 0% to 15% ２ O is 0% or more and 10% or less, K ２ O is 0% or more and 10% or less, SrO is 0% or more and 10% or less, BaO is 0% or more and 10% or less, TiO ２ 0% or more and 10% or less, Ta ２ O ５ 0% to 10%; WO ３ ZnO is 0% or more and 10% or less, La is 0% or more and 30% or less, ２ O ３ Contains 0% or more and 10% or less of ZrO ２ HfO content ２ The method for producing glass according to claim 8 , wherein the ratio of the content of is 0.005 to 0.03, and Sb is not contained.

12. The glass is TeO ２ Content and ZrO ２ The total content of TeO ２ + ZrO ２ The method for producing glass according to claim 8 , wherein the content of the SiO 2 is 3% or more and 40% or less.

13. The method for producing glass according to claim 8, wherein the glass has a Young's modulus of 66 GPa or more.

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