glass

Abstract

The present invention provides a glass that has a high refractive index while suppressing the retention of bubbles and an increase in specific gravity. [Solution] The glass 10 has a refractive index n d The ratio is 1.950 or higher, and in terms of molar percentage based on oxides, it contains B2O3: 0% to 30.0%, SiO2: 0% to 20.0%, BaO: greater than 0% and 20.0%, total of CaO and SrO: greater than 0% and 30.0%, Li2O: 0% to 15.0%, Na2O: 0% to 15.0%, K2O: 0% to 5.0%, Y2O3: 0% to 2.5%, WO3: 0% to 5.0%, Nb2O5: 1.0% to 20.0%, La2O3: 5.0% to 30.0%, ZrO2: 0% to 20.0%, TiO2: 5.0% to 40.0%, and ZnO: 0% to 15.0%.

Description

[Technical Field]

[0001] This invention relates to glass. [Background technology]

[0002] In recent years, there has been a demand for glass with a high refractive index. For example, Patent Documents 1 and 2 describe optical glass with a refractive index of 1.8 to 2.1. In particular, in wearable devices such as head-mounted displays that realize AR (Augmented Reality), VR (Virtual Reality), and MR (Mixed Reality), a high refractive index for visible light is required for the light guide plate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4286652 [Patent Document 2] Patent No. 4562041 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, glass with a high refractive index is prone to bubble formation, and these bubbles may remain in the glass. Furthermore, glass with a high refractive index may have a higher specific gravity. Therefore, there is a need to suppress both bubble formation and increased specific gravity while maintaining a high refractive index.

[0005] The present invention aims to provide a glass that can achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity. [Means for solving the problem]

[0006] The glass relating to this disclosure has a refractive index n d The value is 1.950 or higher, In terms of molar percentage based on oxides, B2O3: 0% or more and 30.0% or less, SiO2: 0% or more and 20.0% or less, BaO: More than 0% and 20.0% or less, Total of CaO and SrO: More than 0% and 30.0% or less, Li2O: 0% or more and 15.0% or less, Na2O: 0% or more and 15.0% or less, K2O: 0% or more and 5.0% or less, Y2O3: 0% or more and 2.5% or less, WO3: 0% or more and 5.0% or less, Nb2O5: 1.0% or more and 20.0% or less, La2O3: 5.0% or more and 30.0% or less, ZrO2: 0% or more and 20.0% or less, TiO2: 5.0% or more and 40.0% or less, ZnO: 0% or more and 15.0% or less, and contains.

Advantages of the Invention

[0007] According to the present invention, while achieving a high refractive index, it is possible to suppress the remaining bubbles and the increase in specific gravity.

Brief Description of the Drawings

[0008] [Figure 1] Figure 1 is a schematic diagram of the glass according to the present embodiment. [Figure 2] Figure 2 is a cross-sectional view when the glass according to the present embodiment is made into a glass plate.

Modes for Carrying Out the Invention

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the present invention is not limited to these embodiments, and if there are multiple embodiments, they may be constructed by combining these embodiments. Furthermore, numerical values ​​include a range of rounding. Also, a numerical range represented by "~" means a numerical range that includes the numbers before and after "~" as the lower and upper limits, respectively, and subsequent uses of "~" refer to the same meaning.

[0010] (Glass) Figure 1 is a schematic diagram of the glass according to this embodiment. As shown in Figure 1, the glass 10 according to this embodiment is a plate-shaped glass plate, but the shape of the glass 10 is not limited to a plate shape and may be arbitrary. In this embodiment, the glass 10 is used as a light guide plate. More specifically, the glass 10 is used as a light guide plate for a head-mounted display. A head-mounted display is a display device (wearable device) that is worn on a person's head. However, the use of the glass 10 is arbitrary and is not limited to being used as a light guide plate, nor is it limited to being used in a head-mounted display.

[0011] (composition) The composition of glass 10 is described below.

[0012] (B2O3) Glass 10 preferably contains B2O3. The B2O3 content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 30.0%, more preferably 5.0% to 25.0%, more preferably 10.0% to 20.0%, more preferably 12.0% to 19.0%, more preferably 13.0% to 18.0%, and more preferably 14.5% to 17.0%. By keeping the upper limit of the B2O3 content within this range, a high refractive index can be appropriately achieved, and an increase in specific gravity can be suppressed.

[0013] (SiO2) Glass 10 preferably contains SiO2. The SiO2 content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 20.0%, more preferably 5.0% to 18.0%, more preferably 5.0% to 17.0%, more preferably 9.0% to 16.0%, more preferably 10.0% to 15.0%, more preferably 10.5% to 14.0%, and more preferably 11.0% to 13.0%. By limiting the SiO2 content to this range, it is possible to reduce the coloration of the glass, increase the transmittance to visible light, and suppress an increase in specific gravity.

[0014] (BaO) Glass 10 contains BaO. The BaO content of glass 10, expressed in molar percentage based on oxide, is greater than 0% and 20.0% or less, preferably between 2.0% and 16.0%, more preferably between 4.0% and 14.0%, more preferably between 6.0% and 13.0%, and more preferably between 8.0% and 12.0%. By having a BaO content within this range, a high refractive index can be appropriately achieved, increasing the transmittance to visible light while suppressing an increase in specific gravity.

[0015] (CaO and SrO) Glass 10 contains at least one of CaO and SrO. The total content of CaO and SrO in glass 10, expressed in molar percentage based on oxides, is greater than 0% and 30.0% or less, preferably 0.5% to 10.0%, more preferably 1.0% to 5.0%, and even more preferably 1.5% to 3.0%. Note that the total content of CaO and SrO refers to the content of SrO if CaO is not present, and the content of CaO if SrO is not present. By keeping the total content of CaO and SrO within this range, solubility can be improved, reducing the likelihood of foam formation while suppressing an increase in specific gravity. Furthermore, by not including excessive amounts of CaO and SrO in this way, a decrease in refractive index can be suppressed.

[0016] Glass 10 preferably has a CaO content of 0% to 15.0% in molar percentage based on oxide, more preferably greater than 0% and 10.0% or less, even more preferably 0.40% to 5.0%, even more preferably 0.6% to 3.0%, and even more preferably 0.7% to 2.0%. By having a CaO content within this range, solubility can be improved, reducing the likelihood of bubbles remaining, while suppressing an increase in specific gravity. Furthermore, by not including an excessive amount of CaO in this way, a decrease in refractive index can be suppressed.

[0017] Glass 10 preferably has a SrO content of 0% to 15.0% in molar percentage based on oxide, more preferably greater than 0% and 10.0% or less, even more preferably 0.3% to 5.0%, even more preferably 0.4% to 4.0%, and even more preferably 0.5% to 3.0%. By having a SrO content within this range, solubility can be improved, reducing the likelihood of bubbles remaining, while suppressing an increase in specific gravity. Furthermore, by not including an excessive amount of SrO in this way, a decrease in refractive index can be suppressed.

[0018] In glass 10, the ratio of the CaO content to the total CaO content (CaO / (CaO+SrO)) in molar percentage based on oxides is preferably 0 to 1.0, more preferably 0.2 to 0.8, and even more preferably 0.4 to 0.6. By having the CaO to SrO content ratio within this range, bubbles can be more effectively prevented from remaining.

[0019] (Li2O) Glass 10 may or may not contain Li2O. The Li2O content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 15.0%, more preferably 0.1% to 10.0%, more preferably 0.3% to 5.0%, more preferably 0.5% to 4.0%, and more preferably 0.7% to 3.0%. By having a Li2O content within this range, solubility can be improved, reducing the likelihood of bubbles while suppressing an increase in specific gravity. Furthermore, by not including an excessive amount of Li2O, a decrease in refractive index can be suppressed. Note that "not contained" means that its presence as an unavoidable impurity is acceptable.

[0020] (Na2O) Glass 10 may or may not contain Na2O. The Na2O content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 15.0%, more preferably 0.1% to 10.0%, more preferably 0.2% to 5.0%, more preferably 0.4% to 2.5%, but more preferably no Na2O. Having a Na2O content within this range improves solubility, reduces foaming, and suppresses an increase in specific gravity.

[0021] (K2O) Glass 10 may or may not contain K2O. The K2O content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 5.0%, more preferably 0.1% to 3.0%, more preferably 0.3% to 1.0%, but most preferably K2O-free. Having a K2O content within this range improves solubility, reduces foaming, and suppresses an increase in specific gravity.

[0022] (Y2O3) Glass 10 may or may not contain Y2O3. The Y2O3 content of glass 10, expressed in molar percentage based on oxide, is preferably 0.1% to 1.5%, more preferably 0.4% to 1.0%, but most preferably no Y2O3. A Y2O3 content within this range allows for the appropriate achievement of a high refractive index.

[0023] (WO3) Glass 10 may or may not contain WO3. The WO3 content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 5.0%, more preferably 0.1% to 3.0%, more preferably 0.4% to 2.0%, more preferably 0.8% to 1.5%, but more preferably no WO3 at all. A WO3 content within this range allows for the appropriate realization of a high refractive index.

[0024] (Nb2O5) Glass 10 contains Nb2O5. The Nb2O5 content of glass 10, expressed in molar percentage based on oxide, is preferably 1.0% to 20.0%, more preferably 2.0% to 10.0%, more preferably 2.4% to 5.0%, and more preferably 2.8% to 3.5%. A high refractive index can be appropriately achieved by having an Nb2O5 content within this range.

[0025] (La2O3) Glass 10 contains La2O3. The La2O3 content of glass 10, expressed in molar percentage based on oxide, is preferably 5% to 30.0%, more preferably 8.0% to 20.0%, more preferably 11.0% to 18.0%, more preferably 12.5% ​​to 17.0%, and more preferably 13.5% to 16.0%. A high refractive index can be appropriately achieved by having a La2O3 content within this range.

[0026] (ZrO2) Glass 10 preferably contains ZrO2. The ZrO2 content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 20.0%, more preferably 1.5% to 15.0%, more preferably 3.0% to 10.0%, and more preferably 4.0% to 8.0%. By limiting the ZrO2 content to this range, a high refractive index can be appropriately achieved.

[0027] (TiO2) Glass 10 contains TiO2. The TiO2 content of glass 10, expressed in molar percentage based on oxide, is 5% to 40.0%, more preferably 15.0% to 38.0%, more preferably 20.0% to 37.0%, more preferably 25.0% to 36.0%, and more preferably 28.0% to 35.5%. A TiO2 content within this range allows for the appropriate achievement of a high refractive index.

[0028] (ZnO) Glass 10 preferably contains ZnO. The ZnO content of glass 10, expressed in molar percentage based on oxide, is preferably 0% to 15.0%, more preferably 0.5% to 10.0%, more preferably 1.0% to 5.0%, more preferably 2.0% to 4.0%, and more preferably 2.5% to 3.5%. By having the upper limit of the ZnO content within this range, a high refractive index can be appropriately achieved.

[0029] (Bi2O3) It is preferable that the glass 10 does not contain Bi2O3. By not containing Bi2O3, it is possible to achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity.

[0030] (TeO2) It is preferable that the glass 10 does not contain TeO2. By not containing TeO2, it is possible to achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity.

[0031] (Pb) It is preferable that the glass 10 does not contain Pb. By not containing Pb, the environmental burden can be appropriately reduced. Here, Pb refers not only to elemental Pb metal contained in the glass 10, but may also include elemental Pb metal and compounds. Whether or not Pb is present can be measured by ICP mass spectrometry. For example, the Agilent 8800 from Agilent Technologies can be used as a measuring instrument.

[0032] (Sb) Glass 10 preferably has a low Sb content. Sb has the effect of reducing bubbles, but by reducing its content, the environmental burden can be appropriately reduced. Here, Sb refers not only to elemental Sb metal contained in glass 10, but may include elemental Sb metal and compounds. Glass 10 has an Sb2O3 content of 0.10% or less, preferably 0.05% or less, more preferably 0.03% or less, more preferably 0.02% or less, more preferably 0.01% or less, and even more preferably no Sb at all, expressed in mole percent on an oxide basis.

[0033] (Li2O / (Li2O+Na2O+K2O)) In glass 10, the ratio of the Li2O content to the total content of Li2O, Na2O, and K2O (Li2O / (Li2O+Na2O+K2O)) in molar percentages based on oxides is preferably 0 to 1.0, more preferably 0.10 to 1.00, more preferably 0.25 to 1.00, and even more preferably 0.50 to 1.00. By having the ratio of the Li2O content to the total content of these divalent oxides within this range, bubbles can be more effectively prevented from remaining.

[0034] ((CaO+SrO) / (La2O3+TiO2)) In glass 10, the ratio of the total content of CaO and SrO to the total content of La2O3 and TiO2 in molar percentage based on oxides ((CaO+SrO) / (La2O3+TiO2)) is preferably 0 to 1.00, more preferably 0.01 to 0.50, preferably 0.02 to 0.20, and even more preferably 0.04 to 0.10. By setting the ratio of the total content of La2O3 and TiO2, which are high refractive index components, to the content of CaO and SrO, which are components that can prevent bubbles from remaining, within this range, it is possible to appropriately achieve both a high refractive index and reduced bubble retention.

[0035] (BaO / (BaO+CaO+SrO)) In glass 10, the ratio of the BaO content to the total content of BaO, CaO, and SrO (BaO / (BaO+CaO+SrO)) in molar percentages based on oxides is preferably 0.1 to 1.00, more preferably 0.30 to 0.95, even more preferably 0.30 to 0.90, and still more preferably 0.50 to 0.85. By having the ratio of the BaO content to the total content of these tetravalent oxides within this range, it is possible to appropriately achieve both a high refractive index and reduced bubble formation.

[0036] (Properties of glass) The properties of glass 10 are described below.

[0037] (Number of bubbles) Glass 10 is 6cm 3 The number of bubbles with a diameter of 30 μm or more inside is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less. This reduces defects inside the glass 10 and improves its optical properties. Note that the glass 10 is 6 cm 3 The number of bubbles with a diameter of 30 μm or more can be measured in accordance with the "JOGIS 12:2019 Method for Measuring Bubbles in Optical Glass" standard of the Japan Optical Glass Manufacturers Association. The number of bubbles is measured using a microscope capable of reading at least 2 μm, or an equivalent device.

[0038] (Specific gravity Sg) The specific gravity Sg of the glass 10 is 5.0 g / cm 3 The following is preferable, 3.50 g / cm 3 or more and 4.90 g / cm 3 The following is more preferable, 4.00 g / cm 3 or more and 4.80 g / cm 3 The following is even more preferable. When the specific gravity is thus low, the handling of the glass 10 becomes easy. The specific gravity Sg can be measured by the Archimedes method.

[0039] (Refractive index n d ) The refractive index n of the glass 10 d is 1.950 or more, preferably 1.980 or more and 2.050 or less, more preferably 1.990 or more and 2.020 or less, and even more preferably 1.991 or more and 2.000 or less. When the refractive index n d is within this range, it has a high refractive index for visible light and appropriate optical properties can be imparted to the glass 10. Note that the refractive index n d refers to the refractive index at the d-line of helium (wavelength 587.6 nm). The refractive index n d can be measured by the V-block method.

[0040] (Abbe number v d ) The Abbe number v of the glass 10 d is preferably 17.00 or more and 30.00 or less, more preferably 20.00 or more and 28.00 or less, and even more preferably 23.00 or more and 26.00 or less. Thereby, appropriate optical properties can be imparted to the glass 10. Note that the Abbe number v d is a value representing the property related to dispersion. The Abbe number v d can be measured by the V-block method.

[0041] (Transmittance τ 440 ) The transmittance τ of the glass 10 440The transmittance τ is preferably 65.0% to 98.0%, more preferably 75.0% to 97.0%, more preferably 85.0% to 96.0%, and even more preferably 90.0% to 95.0%. 440 When it falls within this range, visible light can be transmitted appropriately. Note that the transmittance τ 440 This represents the internal transmittance for light with a wavelength of 440 nm when converted to a thickness of 10 mm.

[0042] (Transmittance τ 460 ) Transmittance τ of glass 10 460 The transmittance τ is preferably 70.0% or higher, more preferably 80.0% to 99.0%, more preferably 90.0% to 98.0%, and even more preferably 95.0% to 97.0%. 460 When it falls within this range, visible light can be transmitted appropriately. Note that the transmittance τ 460 This represents the internal transmittance for light with a wavelength of 460 nm when converted to a thickness of 10 mm.

[0043] Internal transmittance is the transmittance that passes through the interior of the glass 10. Internal transmittance can be determined from the measured values ​​of two types of external transmittances with different plate thicknesses and the following formula (A). External transmittance refers to transmittance including surface reflection loss. In formula (A), τ is the internal transmittance of the glass when converted to a thickness of 10 mm, T1 and T2 are the external transmittances, and Δd is the difference in thickness of the sample. External transmittance can be measured using a spectrophotometer (Hitachi High-Technologies Corporation: U-4100) on a sample with a thickness of 10 mm and mirror polished on both sides.

[0044]

number

[0045] (Young's modulus E) The Young's modulus E of the glass 10 is preferably 100 GPa or more and 140 GPa or less, more preferably 110 GPa or more and 130 GPa or less, and even more preferably 115 GPa or more and 125 GPa or less. Such a high Young's modulus effectively suppresses the breakage of the glass 10. The Young's modulus can be measured based on the propagation of ultrasound using an OLYMPUS 38DL PLUS.

[0046] (Glass transition temperature Tg) The glass transition temperature Tg of glass 10 is preferably 550°C to 800°C, more preferably 600°C to 750°C, even more preferably 630°C to 700°C, and still more preferably 650°C to 680°C. The glass transition temperature can be measured according to the method specified in JIS R3103-3:2001 "Viscosity and viscosity fixed points of glass - Part 3: Method for measuring transition temperature by thermal expansion".

[0047] (devitrification temperature) The devitrification temperature of glass 10 is preferably 1050°C to 1300°C, more preferably 1100°C to 1250°C, and even more preferably 1130°C to 1200°C. The devitrification temperature can be measured by the following method. The sample glass was crushed, passed through a 4 mm sieve, and glass particles remaining on a 2 mm sieve were obtained. These glass particles were immersed in ethanol, ultrasonically cleaned, and then dried in a drying oven. Approximately 5 g of the dried glass particles were placed in a platinum dish and held at 1000°C to 1400°C in 10°C increments for 1 hour each. After cooling by natural cooling, the presence or absence of crystal precipitation was observed under a microscope, and the lowest temperature at which no crystals larger than 1 μm in length or diameter were observed was defined as the devitrification temperature.

[0048] (Vickers hardness) The Vickers hardness of glass 10 is preferably between 450 HV and 750 HV, more preferably between 500 HV and 700 HV, and even more preferably between 550 HV and 650 HV. A Vickers hardness within this range improves the wear resistance of glass 10. Vickers hardness can be evaluated using a Future Tech Vickers hardness tester (FV-800) under conditions of a load of 0.5 kgf and a pressurization time of 15 seconds.

[0049] (Form of glass) The glass 10 according to this embodiment is preferably optical glass, and a glass plate with a thickness of 0.01 mm or more and 2.0 mm or less is preferred. If the thickness is 0.01 mm or more, breakage during handling and processing of the glass 10 can be suppressed. Also, deflection due to the weight of the glass 10 can be suppressed. This thickness is more preferably 0.1 mm or more, even more preferably 0.2 mm or more, and even more preferably 0.3 mm or more. On the other hand, if the thickness is 2.0 mm or less, the optical element using the glass 10 can be made lighter. 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.

[0050] In the case where the glass 10 in this embodiment is a glass plate, the area of ​​the main surface is 8 cm². 2 The above is preferable. This area is 8 cm². 2 If the area is larger than this, a large number of optical elements can be arranged, improving productivity. This area is more preferably 30 cm². 2 The above, and more preferably 170 cm 2 The above, and more preferably 300 cm 2 The above, and especially preferably 1000 cm 2 That's all. On the other hand, the area is 6500 cm². 2 The following conditions make handling the glass plate easier and reduce breakage during handling and processing. This area is more preferably 4500 cm². 2 The following, and more preferably 4000 cm 2 The following, and more preferably 3000 cm 2The following, and especially preferably 2000 cm 2 The following applies:

[0051] In the case where the glass 10 according to this embodiment is a glass plate, the main surface is 25 cm 2 The Local Thickness Variation (LTV) in this material is preferably 2 μm or less. Having a flatness within this range allows for the formation of nanostructures of a desired shape on the main surface using imprint technology, etc., and enables the acquisition of desired light-guiding characteristics. In particular, it prevents ghosting and distortion caused by differences in optical path length in the light guide. This LTV is more preferably 1.5 μm or less, even more preferably 1.0 μm or less, and particularly preferably 0.5 μm or less.

[0052] When the glass 10 according to this embodiment is a circular glass plate with a diameter of 8 inches, the warp is preferably 50 μm or less. If the warp of this glass 10 is 50 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The warp 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.

[0053] Furthermore, when the glass 10 according to this embodiment is a circular glass plate with a diameter of 6 inches, the curvature is preferably 30 μm or less. If the curvature of this glass 10 is 30 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The curvature of this glass 10 is more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0054] Furthermore, when the glass 10 according to this embodiment is a square glass plate with sides of 6 inches, the warp is preferably 100 μm or less. If the warp of this glass 10 is 100 μm or less, a nanostructure of the desired shape can be formed on the main surface using imprint technology or the like, and the desired light-guiding properties can be obtained. When trying to obtain multiple light guides, stable quality can be obtained. The warp of this glass 10 is more preferably 70 μm or less, even more preferably 50 μm or less, even more preferably 35 μm or less, and particularly preferably 20 μm or less.

[0055] Figure 2 is a cross-sectional view of the glass according to this embodiment when it is a glass plate. "Warping" is the difference C between the maximum value B and the minimum value A of the vertical distance between the reference line G1D of the glass plate G1 and the center line G1C of the glass plate G1, in any cross section that passes through the center of the main surface G1F of the glass plate G1 and is perpendicular to the main surface G1F of the glass plate G1.

[0056] The intersection line between the aforementioned orthogonal cross-sections and the main surface G1F of the glass plate G1 is defined as the bottom line G1A. The intersection line between the aforementioned orthogonal cross-sections and the other main surface G1G of the glass plate G1 is defined as the top line G1B. Here, the center line G1C is the line connecting the centers of the glass plate G1 in the thickness direction. The center line G1C is calculated by finding the midpoint between the bottom line G1A and the top line G1B with respect to the direction of laser irradiation, which will be described later.

[0057] The baseline G1D is determined as follows: First, the base line G1A is calculated using a measurement method that cancels out the effect of the self-weight. From this base line G1A, a straight line is determined using the least squares method. The resulting straight line is the baseline G1D. A known method is used as the measurement method that cancels out the effect of the self-weight.

[0058] For example, the main surface G1F of a glass plate G1 is supported at three points, and a laser is shone onto the glass plate G1 using a laser displacement meter to measure the height of the main surface G1F and other main surfaces G1G of the glass plate G1 from an arbitrary reference plane.

[0059] Next, the glass plate G1 is inverted, and three points on the other main surface G1G opposite to the three points supporting one main surface G1F are supported, and the heights of the main surface G1F and the other main surface G1G of the glass plate G1 are measured from an arbitrary reference plane. The effect of self-weight is canceled out by calculating the average height of each measurement point before and after inversion. For example, before inversion, measure the height of the main surface G1F as described above. After inverting the glass plate G1, measure the height of the other main surface G1G at the position corresponding to the measurement point of the main surface G1F. Similarly, before inversion, measure the height of another main surface G1G. After inverting the glass plate G1, measure the height of the main surface G1F at the position corresponding to the measurement point of the other main surface G1G. Warpage is measured, for example, by a laser displacement meter.

[0060] Furthermore, in the glass 10 according to this embodiment, the surface roughness Ra of the main surface is preferably 2 nm or less. Having Ra within this range allows for the formation of nanostructures of a desired shape on the main surface using imprint technology or the like, and enables the acquisition of desired light-guiding properties. In particular, diffuse reflection at the interface is suppressed in the light guide, preventing ghosting and distortion. This Ra is more preferably 1.7 nm or less, even more preferably 1.4 nm or less, even more preferably 1.2 nm or less, and particularly preferably 1 nm or less. Here, the surface roughness Ra is the arithmetic mean roughness as defined in JIS B0601 (2001). In this specification, it is the value measured using an atomic force microscope (AFM) over a 10 μm × 10 μm area.

[0061] (Method of manufacturing glass) The method for manufacturing the glass 10 according to this embodiment is not particularly limited, and existing plate glass manufacturing methods such as the float method, fusion method, and roll-out method can be used. In addition, known methods such as slicing a cast glass ingot to cut out a glass plate can also be used. However, in order to suppress the deterioration of transmittance due to the inclusion of impurities, it is preferable that the material of the container (crucible) in which the raw materials are placed when melting the raw materials be at least one of Pt, Au, and Au alloy.

[0062] Furthermore, in the melting process of the glass 10 of this embodiment, it is preferable to increase the water content in the molten glass during the process of heating and melting the glass raw material in a melting container to obtain molten glass. The operation to increase the water content in the glass is not limited, but for example, it may be a process of adding water vapor to the molten atmosphere or a process of bubbling a gas containing water vapor into the molten material. Increasing the water content is not essential, but it can be done for purposes such as improving transmittance and clarity. Furthermore, the glass 10 of this embodiment that contains alkali metal oxides such as Li2O or Na2O can be chemically strengthened by substituting Li ions with Na ions or K ions, or Na ions with K ions. In other words, the strength of optical glass can be improved by chemical strengthening treatment.

[0063] (effect) As explained above, the glass 10 according to the first aspect of this disclosure has a refractive index n d It is 1.950 or higher, and in the mol% expression based on oxides, B2O3: 0% or more and 30.0% or less, SiO2: 0% to 20.0% BaO: Greater than 0% and less than or equal to 20.0% Total of CaO and SrO: Greater than 0% and less than or equal to 30.0% Li2O: 0% or more and 15.0% or less, Na2O: 0% to 15.0%, K2O: 0% or more and 5.0% or less, Y2O3: 0% or more and 2.5% or less, WO3: 0% to 5.0% Nb2O5: 1.0% to 20.0% La2O3: 5.0% or more and 30.0% or less, ZrO2: 0% or more and 20.0% or less, TiO2: 5.0% to 40.0% ZnO: 0% or more and 15.0% or less, It contains. The glass 10 in this disclosure has a refractive index n dBy having a refractive index of 1.950 or higher and the above composition, it is possible to achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity.

[0064] The glass 10 according to the second aspect of this disclosure is the glass 10 according to the first aspect, and it is preferable that the internal transmittance for light with a wavelength of 460 nm, when converted to a thickness of 10 mm, is 70% or more. Because the glass 10 of this disclosure has a high transmittance of visible light, it can be appropriately used as an optical component.

[0065] The glass 10 according to the third aspect of this disclosure is the glass 10 of the first or second aspect, with a specific gravity Sg of 5.0 g / cm³. 3 The following is preferable: Because the glass 10 of this disclosure has such a low specific gravity, it can be easily handled.

[0066] The glass 10 according to the fourth aspect of this disclosure is the glass 10 according to any of the first to third aspects, and it is preferable that the ratio of the BaO content to the total content of BaO, CaO, and SrO in mol% based on oxides is 0.1 or more and 1.0 or less. This makes it possible to appropriately prevent bubbles from remaining.

[0067] The glass 10 according to the fifth aspect of this disclosure is the glass 10 of any of the first to fourth aspects, and it is preferable that the ratio of the total content of CaO and SrO to the total content of La2O3 and TiO2 in molar percentage based on oxides is 0 or more and 1.00 or less. This makes it possible to appropriately achieve both a high refractive index and reduced bubble formation.

[0068] The glass 10 according to the sixth aspect of this disclosure is preferably the glass 10 of any of the first to fifth aspects, and is free of Bi2O3 and TeO2. This makes it possible to achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity.

[0069] The glass 10 according to the seventh aspect of this disclosure is preferably the glass 10 of any of the first to sixth aspects, and is Pb-free. This allows for an appropriate reduction in the environmental burden.

[0070] The glass 10 according to the eighth aspect of this disclosure is preferably the glass 10 of any of the first to seventh aspects, and is used as a light guide plate. The glass 10 of this disclosure is appropriately used as a light guide plate.

[0071] (Examples) Next, examples will be described. Tables 1 and 2 show the glass used in each example. Note that the embodiments may be modified as long as the effects of the invention are achieved.

[0072] [Table 1] [Table 2]

[0073] (Example 1) In Example 1, glass with thicknesses of 10 mm and 1 mm was manufactured using the compositions listed in Table 1. Specifically, the raw materials with the compositions shown in Table 1 were uniformly mixed and melted in a platinum crucible at 1300°C for 2 hours to obtain uniform molten glass. Next, the molten glass was poured into a carbon mold with dimensions of 60 mm (length) x 50 mm (width) x 30 mm (height). After holding at 690°C for 1 hour, it was cooled to room temperature at a rate of approximately 1°C / minute to obtain a glass block. Next, the glass block was cut to 30 mm x 30 mm using a cutting machine (small cutting machine manufactured by Maruto Co., Ltd.), and the plate thickness was adjusted and the surface polished using a grinding machine (SGM-6301 manufactured by Shuwa Kogyo Co., Ltd.) and a single-sided polishing machine (EJ-380IN manufactured by Nippon Engis Co., Ltd.) to produce glass with dimensions of 30 mm x 30 mm and thicknesses of 10 mm and 1 mm.

[0074] The refractive index n of the glass in Example 1 d , Abbe number v d , transmittance τ 440 , transmittance τ460 The specific gravity (Sg), Young's modulus (E), glass transition temperature (Tg), devitrification temperature, Vickers hardness, and number of bubbles were measured. The measurement method used was the one described in the above embodiment. The results of each measurement are shown in Table 2.

[0075] (Examples 2-23) In Examples 2 to 23, the glass was manufactured and measured using the same method as in Example 1, except that the composition was as shown in Table 1.

[0076] (evaluation) Each example of glass was evaluated. The specific gravity was 5.0 g / cm³. 3 A sample was deemed to pass if it met both of the following conditions: the following conditions and the number of bubbles being three or less. A sample that did not meet at least one of these conditions was deemed to fail.

[0077] As shown in Table 2, the glass samples in Examples 1-6 and 9-23, which are examples, passed the evaluation, demonstrating that they can achieve a high refractive index while suppressing the retention of bubbles and an increase in specific gravity. On the other hand, the glass sample in Comparative Example 7-8 failed the evaluation, demonstrating that it does not achieve the effect of suppressing the retention of bubbles and an increase in specific gravity while achieving a high refractive index.

[0078] Although embodiments of the present invention have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of symbols]

[0079] 10 Glass

Claims

1. Refractive index n ｄ The value is 1.950 or higher, In the expression of mol% based on oxides, B ２ O ３ : 0% or more, 30% or less SiO ２ : 0% or more, 20% or less BaO: greater than 0% and less than or equal to 20.0% Total of CaO and SrO: Greater than 0% and less than or equal to 30.0% Li ２ O: 0% to 15.0% Na ２ O: 0% to 15.0% K ２ O: 0% or more, 5.0% or less Y ２ O ３ 0% to 2.5% WO ３ : 0% or more, 5.0% or less Nb ２ O ５ : 1.0% to 20.0% La ２ O ３ 5.0% to 30.0% ZrO ２ : 0% or more, 20% or less TiO ２ : 5.0% to 40.0% ZnO: 0% or more and 15.0% or less, Contains Glass.

2. The internal transmittance for light with a wavelength of 460 nm, when converted to a thickness of 10 mm, is 70% or more. The glass according to claim 1.

3. Specific gravity is 5.0 g / cm³ ３ The following is: The glass according to claim 1 or claim 2.

4. In the oxide-based mole percent expression, the ratio of the BaO content to the total content of BaO, CaO, and SrO is 0.1 or more and 1.0 or less. The glass according to claim 1 or claim 2.

5. In the expression of molar percentage based on oxides, La ２ O ３ and TiO ２ The ratio of the total content of CaO and SrO to the total content of [other substances] is between 0 and 1.

00. The glass according to claim 1 or claim 2.

6. Bi ２ O ３ , and TeO ２ It does not contain The glass according to claim 1 or claim 2.

7. It does not contain Pb. The glass according to claim 1 or claim 2.

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

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