Glass plates for light guide plates

Abstract

To provide an optical glass with high refractive index and low density, featuring superior production properties.SOLUTION: The present invention provides: an optical glass in which a refractive index (nd) is 1.81-2.15, a density is 6.0 g / cm3 or less, a glass viscosity is 101dPa s at a temperature T1 of 900 to 1,200°C, a devitrification temperature is 1,300°C or lower, and an SiO2 content is 5 to 44% in terms of mol% display on an oxide basis; and an optical component that uses the optical glass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to optical glass and optical components. [Background technology]

[0002] Glass used in wearable devices, such as projector glasses, eyeglass-type and goggle-type displays, virtual reality and augmented reality display devices, and virtual image display devices, requires a high refractive index for purposes such as a wider image angle, higher brightness and contrast, improved light-guiding properties, and ease of processing diffraction gratings. Furthermore, compact imaging glass lenses with a wide imaging angle have traditionally been used for applications such as in-vehicle cameras and robot visual sensors, and a high refractive index is required for these imaging glass lenses in order to capture a wider range of images in a smaller size.

[0003] Optical glass used in the above applications is required to have a low density in order to provide a comfortable fit for the user and to reduce the overall weight of the device, as lightweight automobiles and robots are required to be. Furthermore, considering use in outdoor environments, it is also important that the surface is less susceptible to deterioration or alteration caused by acid rain and chemicals such as detergents and waxes used in cleaning.

[0004] With regard to glass lenses for vehicles, for example, attempts have been made to increase the refractive index and strength by using lens glass materials for vehicle-mounted cameras that have a certain level of acid resistance, and to further improve acid resistance and water resistance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2013-256446 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the past, when creating a composition with a high refractive index, heavy metal oxides were often used as glass components to increase the refractive index, which generally resulted in a high density of high refractive index glass.

[0007] Wearable devices sometimes use glass formed into sheets, which are produced using efficient forming methods such as the float method, fusion method, and roll-out method. However, the relationship between the temperature during manufacturing and the viscosity of the glass is important for efficient manufacturing. Furthermore, when used as optical components, visible light transmittance is also an important parameter. In the case of high refractive index glass, melting it at high temperatures can result in a decrease in visible light transmittance, especially on the short wavelength side. On the other hand, if the viscosity curve is steep, it becomes difficult to control the viscosity during manufacturing.

[0008] The present invention has been made to solve the above-mentioned problems, and has as its object to provide an optical glass that has a high refractive index, a low density, and good manufacturing properties. [Means for solving the problem]

[0009] The optical glass of the present invention has a refractive index (n d ) is 1.81 to 2.15, and the density is 6.0 g / cm 3 Below, the viscosity of glass is 10 1 It is characterized by a temperature T1 at which it becomes dPa·s of 900 to 1200°C, a devitrification temperature of 1300°C or less, and an SiO2 content of 5% to 44% expressed in mole % on an oxide basis. The optical component of the present invention is characterized by comprising the plate-shaped optical glass of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view illustrating warpage of optical glass. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the optical glass and optical component of the present invention will be described.

[0012] The optical glass of the present invention has a predetermined refractive index (n d ), density (d), and solubility properties, and each of these properties will be discussed in turn. The optical glass of the present invention has a high refractive index (n d ) has a refractive index (n d ) is 1.81 or more, the optical glass of the present invention is suitable as an optical glass for use in wearable devices in terms of widening the image angle, increasing brightness and contrast, improving light guiding properties, and facilitating the processing of diffraction gratings. Furthermore, it is suitable as an imaging glass lens with a small size and a wide imaging angle for use in applications such as in-vehicle cameras and visual sensors for robots, in order to capture images of a wider range in a smaller size. d ) is preferably 1.85 or more, more preferably 1.88 or more, even more preferably 1.91 or more, even more preferably 1.94 or more, even more preferably 1.97 or more, even more preferably 1.99 or more, and even more preferably 2.00 or more. On the other hand, the refractive index (n d Glass with a refractive index (n ) exceeding 2.15 tends to have a high density and a high devitrification temperature. In particular, when low density of optical glass is important, the refractive index (n d ) is preferably 2.10 or less, more preferably 2.06 or less, even more preferably 2.03 or less, even more preferably 2.01 or less, even more preferably 1.98 or less, even more preferably 1.95 or less, even more preferably 1.94 or less, and still more preferably 1.92 or less.

[0013] The optical glass of the present invention has a viscosity of 6.0 g / cm 3The optical glass of the present invention has a density (d) of 5.6 g / cm or less. By having a density within the above range, the optical glass of the present invention can provide a comfortable fit for the user when used in wearable devices, and can reduce the weight of the entire device when used in in-vehicle cameras, visual sensors for robots, etc. This density (d) is preferably 5.6 g / cm. 3 More preferably, it is 5.2 g / cm or less. 3 or less, more preferably 4.8 g / cm 3 or less, more preferably 4.6 g / cm 3 More preferably, 4.4 g / cm or less 3 or less, more preferably 4.2 g / cm 3 The following is the result. On the other hand, in the optical glass of the present invention, in order to make the glass surface less susceptible to scratches, the density (d) is set to 3.3 g / cm 3 The density (d) is preferably 3.6 g / cm or more. 3 More preferably, 3.9 g / cm 3 More preferably, it is 4.2 g / cm or more. 3 More preferably, it is 4.4 g / cm or more. 3 or more, and even more preferably 4.7 g / cm 3 That's all.

[0014] In addition, the optical glass of the present invention has a viscosity of 10 1 The temperature T1 at which the viscosity reaches dPa·s is in the range of 900 to 1200°C. T1 is the reference temperature for melting, and if the T1 of the glass is too high, it will need to be melted at a high temperature, which can reduce the visible light transmittance, especially on the short wavelength side, in the case of high refractive index glass. This T1 is preferably 1180°C or lower, more preferably 1150°C or lower, even more preferably 1130°C or lower, and even more preferably 1110°C or lower. On the other hand, if T1 is too low, the viscosity curve becomes steep, making it difficult to control the viscosity during production. By having T1 within the above-mentioned range, the optical glass of the present invention can have good manufacturing properties. This T1 is preferably 950°C or higher, more preferably 1000°C or higher, even more preferably 1050°C or higher, even more preferably 1080°C or higher, still more preferably 1100°C or higher, and particularly preferably 1120°C or higher.

[0015] The optical glass of the present invention also has a devitrification temperature of 1300°C or lower. Such properties allow for suppression of devitrification of the glass during molding, resulting in good moldability. This devitrification temperature is more preferably 1275°C or lower, even more preferably 1250°C or lower, even more preferably 1225°C or lower, even more preferably 1200°C or lower, even more preferably 1175°C or lower, even more preferably 1150°C or lower, even more preferably 1125°C or lower, even more preferably 1100°C or lower, even more preferably 1075°C or lower, and particularly preferably 1050°C or lower. The devitrification temperature is the lowest temperature at which, when heated and melted glass is allowed to cool naturally, no crystals with a long side or major axis of 1 μm or more are observed on the surface or inside the glass.

[0016] The optical glass of the present invention preferably has a glass transition point (Tg) of 600°C or higher. By having a Tg of 600°C or higher, the optical glass of the present invention can suppress deformation such as warping during processing. This Tg is more preferably 630°C or higher, even more preferably 660°C or higher, even more preferably 690°C or higher, even more preferably 720°C or higher, and particularly preferably 750°C or higher. When molding such as press molding and redraw molding is performed, the Tg is preferably 800°C or lower. It is more preferably 760°C or lower, even more preferably 720°C or lower, even more preferably 680°C or lower, and particularly preferably 640°C or lower. Tg can be measured, for example, by thermal expansion method.

[0017] Furthermore, the optical glass of the present invention preferably has a viscosity (devitrification viscosity) η at the devitrification temperature expressed in dPa·s, such that logη=0.4 or greater. Such a characteristic can suppress devitrification of the glass during molding, resulting in good moldability. The viscosity at the devitrification temperature is more preferably logη=0.5 or greater, even more preferably logη=0.6 or greater, even more preferably logη=0.7 or greater, and particularly preferably logη=0.8 or greater.

[0018] The optical glass of the present invention has an Abbe number (v d When the optical glass of the present invention is used in a glass plate such as a light guide plate, it is preferable that the low v d This makes it easier to design the optical system for wearable devices and improves chromatic aberration, enabling the reproduction of high-definition images and videos. d is more preferably 50 or less, even more preferably 40 or less, even more preferably 38 or less, even more preferably 35 or less, still more preferably 32 or less, and particularly preferably 30 or less. Furthermore, the optical glass of the present invention has an Abbe number (v d Specifically, when the optical glass of the present invention is used in a glass plate such as a light guide plate, it is preferable that the optical glass has a high v d By having this, it becomes easier to obtain refractive index matching with the resin applied to the surface. d is more preferably 18 or more, even more preferably 21 or more, even more preferably 23 or more, even more preferably 25 or more, still more preferably 27 or more, and particularly preferably 29 or more.

[0019] The thermal expansion coefficient (α) of the optical glass of the present invention at 50 to 350°C is 50 to 150 (×10 -7 / K) is preferable. When the optical glass of the present invention has α in the above range, it has good expansion matching with the surrounding members. The lower limit of α is preferably 60(×10 -7 / K) or more, more preferably 70 (× 10 -7 / K) or more, and more preferably 80 (× 10-7 / K) or more, and particularly preferably 90 (×10 -7 / K) or more.

[0020] Furthermore, when the optical glass of the present invention has α in the above range, cracking during cooling is less likely to occur, allowing for an increased cooling rate. As a result, it is possible to make the difference (Tf-Tg) between the fictive temperature (Tf) and the glass transition temperature (Tg) of the optical glass 0°C or higher, making the glass structure more coarse, and even if the optical glass is subjected to some kind of impact, the densified glass structure makes it easier to absorb the impact. As a result, the strength of the optical glass itself is improved, and breakage due to dropping, etc. can be suppressed. The upper limit of α is preferably 120(×10 -7 / K) or less, more preferably 110(×10 -7 / K) or less, and more preferably 100 (×10 -7 / K) or less, and particularly preferably 95 (×10 -7 / K).

[0021] The optical glass of the present invention is preferably a glass plate having a thickness of 0.01 to 2 mm. A thickness of 0.01 mm or more can prevent breakage of the optical glass during handling or processing. It can also prevent deflection of the optical glass due to its own weight. This thickness is more preferably 0.1 mm or more, even more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. On the other hand, a thickness of 2 mm or less can reduce the weight of optical elements using the optical glass. 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.

[0022] When the optical glass of the present invention is a glass plate, the area of ​​one main surface is 8 cm 2 This area is preferably 8cm or more. 2 If the area is more than 30cm, a large number of optical elements can be arranged, improving productivity. 2 More preferably, 170 cm 2 More preferably, it is 300 cm or more. 2More preferably, it is 1000 cm 2 On the other hand, if the area is 6500 cm 2 If the area is less than 4500 cm, the glass plate can be easily handled and breakage 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.

[0023] When the optical glass of the present invention is a glass plate, 25 cm 2 The 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 one 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 1.8 μm or less, even more preferably 1.6 μm or less, even more preferably 1.4 μm or less, and particularly preferably 1.2 μm or less.

[0024] When the optical glass of the present invention is formed into a circular glass plate with a diameter of 8 inches, the warpage is preferably 50 μm or less. If the warpage of this glass plate is 50 μm or less, a nanostructure of the desired shape can be formed on one 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 substrate is more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0025] Furthermore, when a circular glass plate with a diameter of 6 inches is used, the warpage is preferably 30 μm or less. If the warpage of this glass plate is 30 μm or less, a nanostructure of the desired shape can be formed on one 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 plate is more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0026] Furthermore, when the glass plate is a square with sides of 6 inches, the warpage is preferably 100 μm or less. If the warpage of this glass plate is 100 μm or less, a nanostructure of the desired shape can be formed on one 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 plate 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.

[0027] 1 is a cross-sectional view of a glass plate G1 made of the optical glass of the present invention. "Warpage" is the difference C between the maximum value B and the minimum value A of the perpendicular distance between a reference line G1D of the glass plate G1 and a center line G1C of the glass plate G1 in any cross section passing through the center of one main surface G1F of the glass plate G1 and perpendicular to the one main surface G1F of the glass plate G1.

[0028] The intersection line between the arbitrary orthogonal cross section and one main surface G1F of the glass plate G1 is defined as a base line G1A. The intersection line between the arbitrary orthogonal cross section and another main surface G1G of the glass plate G1 is defined as a top line G1B. Here, the center line G1C is a line connecting the centers of the glass plate G1 in the plate thickness direction. The center line G1C is calculated by finding the midpoint between the base line G1A and the top line G1B with respect to the laser irradiation direction described below.

[0029] 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.

[0030] For example, one 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 one main surface G1F and the other main surface G1G of the glass plate G1 from an arbitrary reference plane is measured.

[0031] Next, the glass plate G1 is inverted, and three points on another main surface G1G opposite to the three points on which one main surface G1F is supported are supported, and the heights of one main surface G1F and the other main surface G1G of the glass substrate G1 from an arbitrary reference plane are measured. The influence of gravity is cancelled out by averaging the heights of the measurement points before and after inversion. For example, before inversion, the height of one main surface G1F is measured as described above. After inverting the glass plate G1, the height of the other main surface G1G is measured at a position corresponding to the measurement point on the one main surface G1F. Similarly, before inversion, the height of the other main surface G1G is measured. After inverting the glass plate G1, the height of the one main surface G1F is measured at a position corresponding to the measurement point on the other main surface G1G. The warpage is measured, for example, by a laser displacement meter.

[0032] Furthermore, in the optical glass of the present invention, the surface roughness Ra of one main surface is preferably 2 nm or less. Having an Ra in this range allows a nanostructure of the desired shape to be formed on the one main surface using imprinting technology or the like, and also allows for the desired light-guiding properties to be obtained. In particular, in a light guide, diffused reflection at the interface can be 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 value is measured over an area of ​​10 μm × 10 μm using an atomic force microscope (AFM).

[0033] [Glass components] Next, one embodiment of the composition range of each component that may be contained in the optical glass of the present invention will be described in detail. In this specification, the content of each component is expressed in mole percent based on the oxide unless otherwise specified. Furthermore, in the optical glass of the present invention, "substantially free" means that the component is not contained except for unavoidable impurities. In the present invention, the content of unavoidable impurities is 0.1% or less.

[0034] The optical glass of this embodiment has a composition that satisfies the above-described characteristics, for example, expressed in mole percent on an oxide basis, that contains 30% to 80% of at least one high refractive index component selected from the group consisting of TiO2, Ta2O5, WO3, Nb2O5, ZrO2, and Ln2O3 (wherein Ln is at least one selected from the group consisting of Y, La, Gd, Yb, and Lu), 20% to 70% of the total content of SiO2 and B2O3 as glass skeleton components, and, if alkaline earth metal components (MgO, CaO, SrO, BaO) are contained, the proportion of BaO among the alkali metal components is 0.5 or less. Each component of glass composition A that satisfies this condition will be specifically explained below. However, the optical glass of the present invention is not limited to the composition of the following embodiment, so long as it has the above-mentioned properties.

[0035] <Glass composition A> SiO2 is a glass-forming component that provides high strength and crack resistance to glass and improves the stability and chemical durability of glass. The SiO2 content is preferably 5% or more and 44% or less. When the SiO2 content is 5% or more and the viscosity of glass is 10 1 The temperature T1 at which the viscosity reaches dPa·s can be set within a preferred range. The SiO2 content is preferably 7% or more, more preferably 9% or more, even more preferably 10% or more, and particularly preferably 11% or more. On the other hand, when the SiO2 content is 44% or less, more components for achieving a high refractive index can be added. The SiO2 content is more preferably 38% or less, more preferably 30% or less, even more preferably 20% or less, even more preferably 15% or less, and particularly preferably 12% or less.

[0036] B2O3 is a component that lowers the Tg, improves mechanical properties such as glass strength and crack resistance, and lowers the devitrification temperature. However, a high B2O3 content tends to lower the refractive index. Therefore, the B2O3 content is preferably 0% or more and 40% or less. The B2O3 content is more preferably 35% or less, even more preferably 30% or less, still more preferably 25% or less, even more preferably 23% or less, and particularly preferably 22% or less. The B2O3 content is more preferably 5% or more, even more preferably 12% or more, still more preferably 18% or more, and particularly preferably 20% or more.

[0037] SiO2 and B2O3 are glass-forming components that improve the stability of glass. A high combined amount of SiO2 and B2O3 lowers the devitrification temperature of glass, making it easier to manufacture. Therefore, the combined amount of SiO2 and B2O3 is 20% or more. 25% or more is preferable, 28% or more is more preferable, 30% or more is even more preferable, and 32% or more is particularly preferable. On the other hand, reducing the combined amount of SiO2 and B2O3 can improve the refractive index. Therefore, when a particularly high refractive index is required, the combined amount is preferably 70% or less, more preferably 50% or less, even more preferably 40% or less, even more preferably 35% or less, even more preferably 33% or less, and particularly preferably 32% or less.

[0038] When B2O3 is contained, if the ratio of SiO2 to B2O3 (SiO2 / B2O3) is large, the glass is prone to devitrification. Therefore, when B2O3 is contained, SiO2 / B2O3 is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, even more preferably 2.0 or less, even more preferably 1.0 or less, still more preferably 0.8 or less, and particularly preferably 0.6 or less.

[0039] TiO2, Ta2O5, WO3, Nb2O5, ZrO2, and Ln2O3 (Ln is at least one element selected from the group consisting of Y, La, Gd, Yb, and Lu) are high-refractive-index components that increase the refractive index of glass. The total content of these components is preferably 30% to 80%. When a particularly high refractive index is required, the total content is preferably 40% or more, more preferably 55% or more, even more preferably 60% or more, even more preferably 65% ​​or more, and particularly preferably 67% or more. On the other hand, if the high-refractive-index component exceeds 80%, devitrification tends to occur. For applications requiring a lower surface roughness (Ra), the total content of these components is more preferably 70% or less, even more preferably 60% or less, even more preferably 50% or less, and particularly preferably 45% or less.

[0040] The total content of alkali metal components (Li2O + Na2O + K2O) is 0% or more and 10% or less. Increasing the amount of these alkali metal components can lower Tg. However, if the amount of Li2O + Na2O + K2O is too high, T1 tends to be low, the viscosity curve becomes steep, and manufacturing characteristics deteriorate. On the other hand, if the amount of Li2O + Na2O + K2O is too low, T1 tends to be high, the melting temperature increases, and high refractive index components such as TiO2 and Nb2O5 are easily reduced, which may cause coloration. Therefore, if Li2O + Na2O + K2O is contained, it is preferably 0.5% or more and 10% or less. Li2O + Na2O + K2O is more preferably 1% or more, even more preferably 2% or more, even more preferably 4% or more, and particularly preferably 5% or more. Furthermore, Li2O + Na2O + K2O is preferably 6% or less, more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less. "Li2O + Na2O + K2O" indicates the total amount of at least one alkali metal oxide component selected from the group consisting of Li2O, Na2O, and K2O. Similarly, below, components connected by "+" indicate the total amount of at least one component selected from the group consisting of the components connected by "+".

[0041] The Li2O content is 0% or more and 10% or less. When Li2O is contained, the content is 0.2% or more and 10% or less. The inclusion of Li2O can improve strength (Kc) and crack resistance (CIL). When the optical glass of the present invention contains Li2O, the content is preferably 1% or more, more preferably 2% or more, even more preferably 4% or more, and particularly preferably 5% or more. On the other hand, if the Li2O content is too high, devitrification tends to occur. When quality against devitrification is particularly required, the Li2O content is preferably 8% or less, more preferably 6% or less, even more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less. When the optical glass of this embodiment is chemically strengthened, the Li2O content is preferably 3.0% or more, more preferably 6.0% or more, even more preferably 9.0% or more, and particularly preferably 11.0% or more.

[0042] Na2O is a component that suppresses devitrification and lowers Tg, and its content is 0% or more and 10% or less. The inclusion of Na2O provides an excellent effect of suppressing devitrification. When the optical glass of the present invention contains Na2O, its content is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if the Na2O content is too high, strength and crack resistance tend to decrease. When strength is particularly required, the Na2O content is preferably 7% or less, more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0043] Since Tg tends to decrease as the combined amount of Li2O and Na2O increases, the combined amount of Li2O and Na2O is preferably 0% or more and 10% or less, more preferably 6% or less, even more preferably 4% or less, still more preferably 2% or less, and particularly preferably 1% or less.

[0044] K2O is a component that suppresses devitrification and lowers Tg, and its content is 0% or more and 10% or less. The inclusion of K2O provides an excellent effect of suppressing devitrification. When the optical glass of the present invention contains K2O, its content is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if the amount of K2O is too high, strength and crack resistance tend to decrease. When strength is particularly required, the K2O content is preferably 7% or less, more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0045] MgO is a component that improves the meltability of glass, suppresses devitrification, and adjusts optical constants such as the Abbe number and refractive index of the glass. On the other hand, a large amount of MgO actually promotes devitrification. Therefore, the MgO content is preferably 0% or more and 10% or less. The MgO content is more preferably 8% or less, and particularly preferably 6% or less. The MgO content is also preferably 0.3% or more, more preferably 0.5% or more, and even more preferably 1% or more.

[0046] CaO is a component that suppresses devitrification, but if the amount of CaO is too high, crack resistance tends to decrease. Therefore, the CaO content is preferably 0% or more and 25% or less. The CaO content is more preferably 20% or less, even more preferably 10% or less, and particularly preferably 6% or less. Furthermore, the CaO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0047] SrO is a component that improves the meltability of glass, suppresses devitrification, and adjusts the optical constants of glass. On the other hand, a large amount of SrO actually promotes devitrification. Therefore, the SrO content is preferably 0% or more and 20% or less. The SrO content is more preferably 15% or less, even more preferably 8% or less, and particularly preferably 4% or less. Furthermore, the SrO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0048] If the total amount of MgO, CaO, and SrO is too high, the glass is more likely to devitrify. Therefore, the total amount of MgO, CaO, and SrO is preferably 30% or less, more preferably 20% or less, even more preferably 12% or less, even more preferably 10% or less, still more preferably 5% or less, and particularly preferably 2% or less.

[0049] BaO is a component that suppresses devitrification, but if the amount of BaO is large, the density tends to increase. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The BaO content is more preferably 25% or less, even more preferably 15% or less, even more preferably 8% or less, and particularly preferably 4% or less. Furthermore, the BaO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0050] When alkaline earth metal components (MgO + CaO + SrO + BaO) are contained, the specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal components (BaO / (MgO + CaO + SrO + BaO)) to 0.5 or less. It is preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. The devitrification temperature can be lowered by increasing the proportion of BaO in the alkali metal components. For applications requiring a lower surface roughness Ra, it is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.4 or more.

[0051] When the total amount of alkali metal components (Li2O + Na2O + KO) and alkaline earth metal components (MgO + CaO + SrO + BaO) is large, the Tg of the glass tends to decrease. Therefore, the total amount of alkali metal components and alkaline earth metal components is preferably 30% or less. It is more preferably 16% or less, even more preferably 12% or less, even more preferably 10% or less, even more preferably 5% or less, and particularly preferably 2% or less.

[0052] Al2O3 is a component that improves chemical durability, but if the Al2O3 content is too high, the glass becomes more susceptible to devitrification. Therefore, the Al2O3 content is preferably 0% or more and 5% or less. The Al2O3 content is more preferably 3% or less, and particularly preferably 2% or less. The Al2O3 content is also more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0053] TiO2 is a component that increases the refractive index of glass and increases the dispersion of glass, and its content is 0% or more and 50% or less. When TiO2 is contained, its content is preferably 10% or more, more preferably 20% or more, even more preferably 25% or more, even more preferably 28% or more, even more preferably 30% or more, and particularly preferably 32% or more. On the other hand, if the amount of TiO2 is too high, coloration is likely to occur and transmittance decreases. Therefore, when transmittance is particularly required, the TiO2 content is preferably 50% or less, more preferably 40% or less, even more preferably 37% or less, even more preferably 35% or less, even more preferably 34% or less, even more preferably 33% or less, and particularly preferably 32% or less.

[0054] When B2O3 is contained, if the ratio of TiO2 to B2O3 (TiO2 / B2O3) is large, it becomes necessary to raise the melting temperature, which makes it easier for Ti to be reduced, causing the glass to become colored and the transmittance to decrease. Therefore, when B2O3 is contained, TiO2 / B2O3 is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, even more preferably 2.0 or less, even more preferably 1.8 or less, even more preferably 1.7 or less, even more preferably 1.6 or less, and particularly preferably 1.5 or less.

[0055] Adding WO3 suppresses devitrification of glass, but adding too much WO3 actually makes the glass more susceptible to devitrification. Therefore, the WO3 content is preferably 0% or more and 10% or less. The WO3 content is more preferably 6% or less, even more preferably 2% or less, even more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. Furthermore, adding WO3 can improve the refractive index of glass. Therefore, when a particularly high refractive index is required, the WO3 content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0056] Nb2O5 increases the refractive index of the glass and also increases the Abbe number (v dThe content of Nb2O5 is 0% or more and 35% or less. The content of Nb2O5 is more preferably 1% or more, even more preferably 2% or more, still more preferably 2.5% or more, still more preferably 3% or more, still more preferably 4% or more, still more preferably 5% or more, and particularly preferably 6% or more. In addition, if the amount of Nb2O5 is too much, devitrification tends to occur. Therefore, for applications requiring a lower surface roughness Ra, the amount is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, still more preferably 6% or less, still more preferably 4% or less, still more preferably 3% or less, still more preferably 2% or less, and particularly preferably 1% or less.

[0057] If the total amount of TiO2, WO3, and Nb2O5 is too small, the refractive index of the glass will decrease. Therefore, the total amount of TiO2, WO3, and Nb2O5 is preferably 10% or more and 50% or less. It is more preferably 15% or more, even more preferably 20% or more, even more preferably 25% or more, and particularly preferably 30% or more.

[0058] Y2O3 is a component that increases the refractive index of the glass and adjusts the T1 of the glass within a preferred range, and its content is 0% or more and 7% or less. The Y2O3 content is preferably 1% or more, more preferably 2% or more, even more preferably 2.5% or more, even more preferably 3% or more, still more preferably 3.5% or more, even more preferably 4% or more, and particularly preferably 5% or more. Furthermore, if the Y2O3 content is too high, devitrification is likely to occur. Therefore, for applications requiring a lower surface roughness Ra, the content is preferably 5% or less, more preferably 4% or less, even more preferably 3.5% or less, and particularly preferably 3% or less.

[0059] ZrO2 is a component that increases the refractive index of glass and enhances the chemical durability of glass, and its content is 0% or more and 20% or less. The inclusion of ZrO2 can improve crack resistance. When ZrO2 is contained, its content is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, even more preferably 6% or more, and particularly preferably 6.5% or more. On the other hand, if the ZrO2 content is too high, devitrification tends to occur. Therefore, for applications requiring a lower surface roughness Ra, the ZrO2 content is preferably 15% or less, even more preferably 10% or less, even more preferably 8% or less, and particularly preferably 7% or less.

[0060] ZnO is a component that improves mechanical properties such as glass strength and crack resistance, and its content is 0% or more and 15% or less. When ZnO is contained, its content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, since a large amount of ZnO makes the glass more susceptible to devitrification, for applications requiring a lower surface roughness Ra, the ZnO content is more preferably 10% or less, even more preferably 5% or less, even more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0061] La2O3 is a component that improves the refractive index of glass, and its content is 0% or more and 35% or less. When La2O3 is contained, its content is preferably 10% or more, more preferably 15% or more, even more preferably 16% or more, even more preferably 18% or more, and particularly preferably 20% or more. On the other hand, if the amount of La2O3 is too high, the mechanical properties deteriorate and the devitrification temperature rises. Therefore, when mechanical properties and manufacturing characteristics are important, the La2O3 content is preferably 30% or less. 25% or less is more preferable, 22% or less is even more preferable, 20% or less is even more preferable, 19% or less, 18% or less is even more preferable, and 17% or less is particularly preferable.

[0062] Gd2O3 is a component that improves the refractive index of glass, and its content is 0% or more and 15% or less. When Gd2O3 is contained, its content is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, even more preferably 4% or more, and particularly preferably 5% or more. On the other hand, if the amount of Gd2O3 is too high, the mechanical properties will deteriorate and the devitrification temperature will increase. Therefore, when mechanical properties and manufacturing characteristics are important, the Gd2O3 content is preferably 10% or less, more preferably 7% or less, even more preferably 5% or less, even more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0063] As the ratio of the total amount of ZrO2, Ta2O5, and Nb2O5 to the total amount of SiO2 and B2O3, (ZrO2 + Ta2O5 + Nb2O5) / (SiO2 + B2O3), increases, the devitrification viscosity of the glass tends to decrease. Therefore, (ZrO2 + Ta2O5 + Nb2O5) / (SiO2 + B2O3) is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, even more preferably 0.4 or less, and particularly preferably 0.35 or less.

[0064] When the ratio of the total amount of Nb2O5, TiO2, WO3, and Ta2O5 to the total amount of La2O3, Gd2O3, Y2O3, and Yb2O3 (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) becomes large, the glass becomes colored and transmittance tends to decrease. Therefore, (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 6.0 or less, still more preferably 5.0 or less, still more preferably 4.5 or less, still more preferably 4.0 or less, still more preferably 3.0 or less, still more preferably 2.5 or less, still more preferably 2.0 or less, still more preferably 1.5 or less, and particularly preferably 1.3 or less. On the other hand, as (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) decreases, the Tg of the glass tends to decrease. Therefore, for applications requiring high heat resistance, (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 0.9 or more, still more preferably 1.1 or more, still more preferably 1.2 or more, still more preferably 1.3 or more, still more preferably 1.4 or more, still more preferably 2.0 or more, still more preferably 3.0 or more, and particularly preferably 3.5 or more.

[0065] As As2O3 is a harmful chemical substance, its use has been discouraged in recent years, and environmental measures are required. Therefore, when environmental impact is a priority, it is preferable that it is not substantially contained, except for unavoidable contamination.

[0066] Furthermore, the optical glass of this embodiment preferably contains at least one of Sb2O3 and SnO2. While these are not essential components, they can be added for purposes such as adjusting refractive index characteristics, improving meltability, suppressing coloration, improving transmittance, clarifying, and improving chemical durability. When these components are contained, their total content is preferably 10% or less, more preferably 5% or less, even more preferably 3% or less, and particularly preferably 1% or less.

[0067] Furthermore, the optical glass of this embodiment preferably contains V2O5. Although V2O5 is not essential, it can be added for purposes such as improving transmittance and clarity. When V2O5 is contained, the content is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0068] Furthermore, the optical glass of this embodiment preferably contains F. Although F is not essential, it can be added for the purposes of improving solubility, transmittance, clarity, etc. When F is contained, the content is preferably 5% or less, and more preferably 3% or less.

[0069] Furthermore, for the optical glass of this embodiment, it is preferable to carry out an operation to increase the water content in the molten glass during the melting process in which glass raw materials are heated and melted in a melting vessel to obtain molten glass. The operation to increase the water content in the glass is not limited, but possible examples include a process of adding water vapor to the melting atmosphere and a process of bubbling a gas containing water vapor into the melt. The operation of increasing the water content is not essential, but can be carried out for the purpose of improving transmittance, clarity, etc.

[0070] Furthermore, the optical glass of this embodiment containing alkali metal oxides such as LiO and NaO can be chemically strengthened by substituting Li ions with Na ions or K ions, and Na ions with K ions. In other words, chemical strengthening treatment can improve the strength of the optical glass.

[0071] <Glass composition A1> The glass composition A1 is the glass composition described above in which the alkaline earth metal component is 5% or less. The components of this glass composition A1 will be described. Components not described in this glass composition A1 are the same as those in the glass composition A, and will therefore be omitted here.

[0072] SiO2 is a glass-forming component that provides high strength and crack resistance to glass, and improves the stability and chemical durability of glass. The SiO2 content is preferably 5% or more and 30% or less. When the SiO2 content is 5% or more and the viscosity of glass is 10 1 The temperature T1 at which the viscosity reaches dPa·s can be set within a preferred range. The SiO2 content is preferably 7% or more, more preferably 9% or more, even more preferably 10% or more, and particularly preferably 11% or more. On the other hand, when the SiO2 content is 30% or less, more components for achieving a high refractive index can be added. The SiO2 content is more preferably 25% or less, more preferably 20% or less, even more preferably 15% or less, even more preferably 13% or less, and particularly preferably 12% or less.

[0073] B2O3 is a component that lowers the Tg, improves mechanical properties such as glass strength and crack resistance, and lowers the devitrification temperature. However, a high B2O3 content tends to lower the refractive index. Therefore, the B2O3 content is preferably 5% or more and 40% or less. The B2O3 content is more preferably 35% or less, even more preferably 30% or less, even more preferably 25% or less, still more preferably 23% or more, and particularly preferably 22% or less. The B2O3 content is more preferably 10% or more, even more preferably 15% or more, even more preferably 18% or more, and particularly preferably 20% or more.

[0074] SiO2 and B2O3 are glass-forming components that improve the stability of glass, and their combined amount is 20% or more and 45% or less. A high combined amount of SiO2 and B2O3 lowers the devitrification temperature of the glass, making it easier to manufacture. Therefore, the combined amount of SiO2 and B2O3 is 20% or more. 25% or more is preferable, 28% or more is more preferable, 30% or more is even more preferable, and 32% or more is particularly preferable. On the other hand, reducing the combined amount of SiO2 and B2O3 can improve the refractive index. Therefore, when a particularly high refractive index is required, the combined amount is preferably 45% or less, more preferably 40% or less, even more preferably 35% or less, even more preferably 33% or less, and particularly preferably 32% or less.

[0075] If the ratio of SiO2 to B2O3, SiO2 / B2O3, is too high, the glass is prone to devitrification, so SiO2 / B2O3 is preferably 1.4 or less, more preferably 1.2 or less, even more preferably 1.0 or less, still more preferably 0.8 or less, and particularly preferably 0.6 or less.

[0076] TiO2, Ta2O5, WO3, Nb2O5, ZrO2, and Ln2O3 (Ln is at least one element selected from the group consisting of Y, La, Gd, Yb, and Lu) are high-refractive-index components that increase the refractive index of glass. The total content of these components is preferably 45% to 80%. When a particularly high refractive index is required, the total content is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, even more preferably 65% ​​or more, and particularly preferably 67% or more. On the other hand, if the high-refractive-index component exceeds 80%, devitrification tends to occur. For applications requiring a lower surface roughness Ra, the total content of these components is more preferably 75% or less, even more preferably 70% or less, and particularly preferably 68% or less.

[0077] MgO is a component that improves the meltability of glass, suppresses devitrification, and adjusts optical constants such as the Abbe number and refractive index of the glass. On the other hand, a large amount of MgO actually promotes devitrification. Therefore, the MgO content is preferably 0% or more and 5% or less. The MgO content is more preferably 4% or less, and particularly preferably 2% or less. The MgO content is also preferably 0.3% or more, more preferably 0.5% or more, and even more preferably 1% or more.

[0078] CaO is a component that suppresses devitrification, but if the amount of CaO is too high, crack resistance tends to decrease. Therefore, the CaO content is preferably 0% or more and 5% or less. The CaO content is more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less. Furthermore, the CaO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0079] SrO is a component that improves the meltability of glass, suppresses devitrification, and adjusts the optical constants of glass. On the other hand, a large amount of SrO actually promotes devitrification. Therefore, the SrO content is preferably 0% or more and 5% or less. The SrO content is more preferably 15% or less, even more preferably 4% or less, and particularly preferably 2% or less. Furthermore, the SrO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0080] If the total amount of MgO, CaO, and SrO is too high, the glass is more likely to devitrify. Therefore, the total amount of MgO, CaO, and SrO is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

[0081] BaO is a component that suppresses devitrification, but if the amount of BaO is large, the density tends to increase. Therefore, when BaO is contained, it is preferably 0% or more and 5% or less. The BaO content is more preferably 4% or less, even more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less. Furthermore, the BaO content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more.

[0082] When alkaline earth metal components (MgO + CaO + SrO + BaO) are contained, the specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal components (BaO / (MgO + CaO + SrO + BaO)) to 0.5 or less. It is preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. The devitrification temperature can be lowered by increasing the proportion of BaO in the alkali metal components. For applications requiring a lower surface roughness Ra, it is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.4 or more.

[0083] When the total amount of alkali metal components (Li2O + Na2O + KO) and alkaline earth metal components (MgO + CaO + SrO + BaO) is large, the Tg of the glass tends to decrease. Therefore, the total amount of alkali metal components and alkaline earth metal components is preferably 15% or less. More preferably, it is 12% or less, even more preferably, it is 10% or less, even more preferably, it is 5% or less, even more preferably, it is 3% or less, and particularly preferably, it is 2% or less.

[0084] If the ratio of TiO2 to B2O3, TiO2 / B2O3, is large, it becomes necessary to raise the melting temperature, which makes it easier for Ti to be reduced, causing the glass to become colored and the transmittance to decrease. Therefore, TiO2 / B2O3 is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.7 or less, even more preferably 1.6 or less, and particularly preferably 1.5 or less.

[0085] The optical glass obtained with the glass composition A1 has a high refractive index (n d ) has a refractive index (n d ) is 1.92 or more. This optical glass is suitable for use in wearable devices in terms of widening the image angle, increasing brightness and contrast, improving light guiding properties, and facilitating the processing of diffraction gratings. It is also suitable for use as a small imaging glass lens with a wide imaging angle for applications such as in-vehicle cameras and visual sensors for robots, as it allows for capturing images of a wider range in a smaller size. This refractive index (n d ) is preferably 1.95 or more, more preferably 1.97 or more, even more preferably 1.98 or more, even more preferably 1.99 or more, and even more preferably 2.00 or more. On the other hand, the refractive index (n d Glass with a refractive index (n ) exceeding 2.15 tends to have a high density and a high devitrification temperature. In particular, when low density of optical glass is important, the refractive index (n d) is preferably 2.10 or less, more preferably 2.06 or less, even more preferably 2.03 or less, even more preferably 2.01 or less, even more preferably 1.98 or less, even more preferably 1.95 or less, even more preferably 1.94 or less, and still more preferably 1.93 or less.

[0086] In addition, the optical glass obtained from the glass composition A1 has a viscosity of 4.0 g / cm 3 More than 6.0g / cm 3 This optical glass has a density (d) of 5.8 g / cm or less. By having a density in the above range, when used in wearable devices, it can provide a comfortable fit for the user, and when used in in-vehicle cameras, visual sensors for robots, etc., it can reduce the weight of the entire device. This density (d) is preferably 5.8 g / cm. 3 More preferably, it is 5.6 g / cm or less. 3 or less, more preferably 5.4 g / cm 3 More preferably, 5.2 g / cm or less 3 or less, more preferably 5.1 g / cm 3 More preferably 5.0 g / cm or less 3 The following is the result. On the other hand, to make the surface of optical glass less susceptible to scratches, the density (d) should be 4.0 g / cm 3 More preferably, 4.3 g / cm 3 More preferably, 4.6 g / cm 3 or more, and even more preferably 4.7 g / cm 3 More preferably, 4.8 g / cm 3 That's all.

[0087] <Glass composition A2> The glass composition A2 is the same as the glass composition A described above, except that the alkaline earth metal component is more than 5% and not more than 50% and the B2O3 is less than 15%. The components of this glass composition A2 will be described below. Components not described in this glass composition A2 are the same as those in the glass composition A described above, and therefore will be omitted here.

[0088] SiO2 is a glass-forming component that provides high strength and crack resistance to glass and improves the stability and chemical durability of glass. The SiO2 content is preferably 5% or more and 44% or less. When the SiO2 content is 5% or more and the viscosity of glass is 10 1 The temperature T1 at which the viscosity reaches dPa·s can be set within a preferred range. The SiO2 content is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, even more preferably 24% or more, even more preferably 28% or more, and particularly preferably 30% or more. On the other hand, when the SiO2 content is 44% or less, components for achieving a high refractive index can be added. The SiO2 content is more preferably 37% or less, even more preferably 35.5% or less, even more preferably 34% or less, even more preferably 33% or less, and particularly preferably 31% or less.

[0089] B2O3 is a glass-forming component and is an optional component. B2O3 lowers Tg, improves mechanical properties such as glass strength and crack resistance, and lowers the devitrification temperature. In consideration of the balance between refractive index and mechanical strength, the B2O3 content is preferably 0% or more and less than 15%. The B2O3 content is more preferably 14% or less, even more preferably 13% or less, still more preferably 12% or less, still more preferably 11% or more, and particularly preferably 10% or less. The B2O3 content is more preferably 1% or more, even more preferably 3% or more, still more preferably 5% or more, and particularly preferably 7% or more.

[0090] SiO2 and B2O3 are glass-forming components that improve the stability of glass, and their combined content is 30% to 70%. A high combined content of SiO2 and B2O3 lowers the devitrification temperature of the glass, making it easier to manufacture. Therefore, the combined content of SiO2 and B2O3 is 30% or more. 32% or more is preferred, 34% or more is more preferred, 36% or more is even more preferred, and 37% or more is particularly preferred. On the other hand, reducing the combined content of SiO2 and B2O3 can improve the refractive index. Therefore, when a particularly high refractive index is required, the combined content is preferably 70% or less, more preferably 60% or less, even more preferably 50% or less, even more preferably 40% or less, and particularly preferably 35% or less.

[0091] When B2O3 is contained, if the ratio of SiO2 to B2O3, SiO2 / B2O3, is large, the glass is prone to devitrification. Therefore, when B2O3 is contained, SiO2 / B2O3 is preferably 5.0 or less, more preferably 4.5 or less, even more preferably 4.0 or less, still more preferably 3.5 or less, and particularly preferably 3.0 or less.

[0092] TiO2, Ta2O5, WO3, Nb2O5, ZrO2, and Ln2O3 (Ln is at least one element selected from the group consisting of Y, La, Gd, Yb, and Lu) are high-refractive-index components that increase the refractive index of glass. The total content of these components is preferably 30% to 55%. When a particularly high refractive index is required, the total content is preferably 33% or more, more preferably 35% or more, even more preferably 36% or more, even more preferably 37% or more, and particularly preferably 38% or more. On the other hand, if the content of these high-refractive-index components increases, devitrification becomes more likely. For applications requiring a lower surface roughness (Ra), the total content of these components is more preferably 50% or less, even more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less.

[0093] The total content of alkali metal components (Li2O + Na2O + K2O) is 0% or more and 10% or less. Increasing the amount of these alkali metal components can lower Tg. However, if the amount of Li2O + Na2O + K2O is too high, T1 tends to be low, the viscosity curve becomes steep, and manufacturing characteristics deteriorate. On the other hand, if the amount of Li2O + Na2O + K2O is too low, T1 tends to be high, the dissolution temperature increases, and coloration may occur. Therefore, when Li2O + Na2O + K2O is contained, it is preferably 0.5% or more and 10% or less. Li2O + Na2O + K2O is more preferably 1% or more, even more preferably 1.5% or more, even more preferably 2% or more, and particularly preferably 3% or more. Furthermore, Li2O + Na2O + K2O is preferably 6% or less, more preferably 4% or less, even more preferably 3% or less, and particularly preferably 2% or less.

[0094] The Li2O content is 0% or more and 10% or less. When Li2O is contained, the content is 0.2% or more and 10% or less. Inclusion of Li2O can improve strength (Kc) and crack resistance (CIL). When the optical glass of the present invention contains Li2O, the content is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, and particularly preferably 2% or more. On the other hand, if the Li2O content is too high, devitrification is likely to occur. When devitrification is particularly problematic, the Li2O content is preferably 8% or less, more preferably 6% or less, even more preferably 4% or less, and particularly preferably 2% or less. When the optical glass of this embodiment is chemically strengthened, the Li2O content is preferably 3.0% or more, more preferably 6.0% or more, even more preferably 9.0% or more, and particularly preferably 11.0% or more.

[0095] CaO is a component that suppresses devitrification, but if the amount of CaO is too high, crack resistance tends to decrease. Therefore, the CaO content is preferably 0% or more and 25% or less. The CaO content is more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, even more preferably 8% or less, even more preferably 7% or less, and particularly preferably 6.5% or less. Furthermore, the CaO content is more preferably 2% or more, even more preferably 4% or more, even more preferably 5% or more, and particularly preferably 6% or more.

[0096] SrO is a component that improves the meltability of glass, suppresses devitrification, and adjusts the optical constants of glass. On the other hand, a large amount of SrO actually promotes devitrification. Therefore, the SrO content is preferably 0% or more and 20% or less. The SrO content is more preferably 15% or less, even more preferably 10% or less, still more preferably 9% or less, even more preferably 8% or less, and particularly preferably 7% or less. Furthermore, the SrO content is more preferably 2% or more, even more preferably 4% or more, and particularly preferably 6% or more.

[0097] If the total amount of MgO, CaO, and SrO is too high, the glass is more likely to devitrify. Therefore, the total amount of MgO, CaO, and SrO is preferably 30% or less, more preferably 25% or less, even more preferably 18% or less, even more preferably 16% or less, still more preferably 15% or less, and particularly preferably 14% or less.

[0098] BaO is a component that suppresses devitrification, but if the amount of BaO is large, the density tends to increase. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The BaO content is more preferably 20% or less, even more preferably 15% or less, even more preferably 11% or less, still more preferably 9% or less, and particularly preferably 8% or less. Furthermore, the BaO content is more preferably 2% or more, even more preferably 4% or more, and particularly preferably 6% or more.

[0099] The total content of alkaline earth metal components (MgO + CaO + SrO + BaO) is 5% or more and 50% or less. A total content of 50% or less is preferable because it can prevent devitrification of the glass. It is more preferably 40% or less, even more preferably 30% or less, even more preferably 27% or less, even more preferably 25% or less, even more preferably 23% or less, even more preferably 21% or less, and particularly preferably 20% or less. A total content of 5% or more is preferable because it can improve the meltability of the glass. It is more preferably 10% or more, even more preferably 13% or more, even more preferably 16% or more, even more preferably 18% or more, and particularly preferably 19% or more.

[0100] The specific gravity can be reduced by setting the ratio of BaO (BaO / (MgO+CaO+SrO+BaO)) in the alkaline earth metal components (MgO+CaO+SrO+BaO) to 0.5 or less. It is preferably 0.45 or less, more preferably 0.42 or less, even more preferably 0.40 or less, and particularly preferably 0.35 or less. Increasing the proportion of BaO in the alkaline earth metal components can lower the devitrification temperature and improve manufacturing characteristics. When manufacturing characteristics are particularly important, it is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.35 or more.

[0101] When the total amount of alkali metal components (Li2O + Na2O + KO) and alkaline earth metal components (MgO + CaO + SrO + BaO) is large, the Tg of the glass tends to decrease. Therefore, the total amount of alkali metal components and alkaline earth metal components is preferably 30% or less. It is more preferably 16% or less, even more preferably 14% or less, even more preferably 13% or less, even more preferably 12% or less, and particularly preferably 11.5% or less.

[0102] TiO2 is a component that increases the refractive index of glass and increases the dispersion of glass, and its content is 0% or more and 50% or less. When TiO2 is contained, its content is preferably 10% or more, more preferably 15% or more, even more preferably 17% or more, even more preferably 19% or more, still more preferably 20% or more, and particularly preferably 22% or more. On the other hand, if the amount of TiO2 is too high, coloration is likely to occur and transmittance decreases. Therefore, when transmittance is particularly required, the TiO2 content is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 25% or less, still more preferably 23% or less, even more preferably 22% or less, and particularly preferably 21% or less.

[0103] When B2O3 is contained, if the ratio of TiO2 to B2O3 (TiO2 / B2O3) is large, the melting temperature must be raised, which makes it easier for Ti to be reduced, causing the glass to become colored and the transmittance to decrease. Therefore, when B2O3 is contained, TiO2 / B2O3 is preferably 5.0 or less, more preferably 4.5 or less, even more preferably 4.0 or less, even more preferably 3.5 or less, even more preferably 3.0 or less, even more preferably 2.8 or less, and particularly preferably 2.7 or less.

[0104] Nb2O5 increases the refractive index of the glass and also increases the Abbe number (v d The content of Nb2O5 is 0% or more and 35% or less. The content of Nb2O5 is preferably 2% or more, more preferably 4% or more, even more preferably 5% or more, still more preferably 6% or more, still more preferably 7% or more, still more preferably 8% or more, and particularly preferably 10% or more. In addition, if the amount of Nb2O5 is too much, devitrification occurs easily, so for applications requiring a lower surface roughness Ra, the amount is preferably 20% or less, more preferably 10% or less, even more preferably 8% or less, and particularly preferably 7% or less.

[0105] As the total content of TiO2, WO3, and Nb2O5 decreases, the refractive index of the glass decreases. Therefore, the total content of TiO2, WO3, and Nb2O5 is preferably 10% or more and 50% or less. It is more preferably 14% or more, even more preferably 18% or more, even more preferably 22% or more, and particularly preferably 26% or more. On the other hand, as the total content of TiO2, WO3, and Nb2O5 increases, devitrification becomes more likely. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, and particularly preferably 28% or less.

[0106] ZrO2 is a component that increases the refractive index of glass and enhances the chemical durability of glass, and its content is 0% or more and 20% or less. Inclusion of ZrO2 can improve crack resistance. When ZrO2 is contained, its content is more preferably 1% or more, even more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if the ZrO2 content is too high, devitrification tends to occur. Therefore, when manufacturing properties are particularly important, the ZrO2 content is more preferably 15% or less, even more preferably 10% or less, even more preferably 6% or less, and particularly preferably 5% or less.

[0107] ZnO is a component that improves mechanical properties such as strength and crack resistance of glass, and its content is 0% or more and 15% or less. When ZnO is contained, its content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, since a large amount of ZnO makes devitrification more likely, the ZnO content is more preferably 10% or less, even more preferably 5% or less, even more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0108] La2O3 is a component that improves the refractive index of glass, and its content is 0% or more and 35% or less. When La2O3 is contained, its content is preferably 2% or more, more preferably 4% or more, even more preferably 5% or more, even more preferably 6% or more, and particularly preferably 7% or more. On the other hand, if the amount of La2O3 is too high, the mechanical properties deteriorate and the devitrification temperature rises. Therefore, when mechanical properties and manufacturing characteristics are important, the La2O3 content is preferably 30% or less. 25% or less is more preferable, 20% or less is even more preferable, 15% or less is even more preferable, 10% or less is even more preferable, 9% or less is even more preferable, and 8% or less is particularly preferable.

[0109] When the ratio of the total amount of Nb2O5, TiO2, WO3, and Ta2O5 to the total amount of La2O3, Gd2O3, Y2O3, and Yb2O3 (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) becomes large, the glass becomes colored and transmittance tends to decrease. Therefore, (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 6.0 or less, still more preferably 5.0 or less, even more preferably 4.5 or less, and particularly preferably 4.0 or less. On the other hand, as (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) becomes smaller, the Tg of the glass tends to decrease. Therefore, for applications requiring high heat resistance, (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) is preferably 0.5 or greater, more preferably 1.0 or greater, even more preferably 2.0 or greater, even more preferably 3.0 or greater, and particularly preferably 3.5 or greater.

[0110] The optical glass obtained with the glass composition A2 has a high refractive index (n d ) has a refractive index (n d) is 1.81 or more. This optical glass is suitable for use in wearable devices in terms of widening the image angle, increasing brightness and contrast, improving light guide characteristics, and facilitating the processing of diffraction gratings. It is also suitable for use as a small imaging glass lens with a wide imaging angle for applications such as in-vehicle cameras and visual sensors for robots, as it allows for capturing images of a wider range in a smaller size. This refractive index (n d ) is preferably 1.84 or more, more preferably 1.86 or more, even more preferably 1.87 or more, even more preferably 1.88 or more, still more preferably 1.89 or more, and particularly preferably 1.90 or more. On the other hand, the refractive index (n d Glass with a refractive index (n ) exceeding 1.96 tends to have a high density and a high devitrification temperature. In particular, when low density of optical glass is important, the refractive index (n d ) is preferably 1.94 or less, more preferably 1.93 or less, even more preferably 1.92 or less, even more preferably 1.91 or less, even more preferably 1.90 or less, even more preferably 1.89 or less, even more preferably 1.88 or less, and still more preferably 1.87 or less.

[0111] In addition, the optical glass obtained from glass composition A2 has a density of 3.3 g / cm 3 More than 5.4g / cm 3 This optical glass has a density (d) of 5.2 g / cm or less. By having a density in the above range, when used in wearable devices, it can provide a comfortable fit for the user, and when used in in-vehicle cameras, visual sensors for robots, etc., it can reduce the weight of the entire device. This density (d) is preferably 5.2 g / cm. 3 More preferably, it is 5.0 g / cm or less. 3 or less, more preferably 4.8 g / cm 3 or less, more preferably 4.6 g / cm 3 or less, more preferably 4.4 g / cm 3 or less, more preferably 4.2 g / cm 3 The following is the result. On the other hand, to make the surface of optical glass less susceptible to scratches, the density (d) should be 3.6 g / cm 3 More preferably, it is 3.8 g / cm or more. 3 More preferably, 4.0 g / cm 3 More preferably, it is 4.2 g / cm or more. 3 More preferably, 4.3 g / cm 3 That's all.

[0112] Furthermore, this optical glass has a devitrification temperature of 1300°C or lower. Such properties allow for suppression of devitrification of the glass during molding, resulting in good moldability. The devitrification temperature is more preferably 1275°C or lower, even more preferably 1240°C or lower, even more preferably 1225°C or lower, even more preferably 1200°C or lower, even more preferably 1175°C or lower, even more preferably 1150°C or lower, even more preferably 1125°C or lower, even more preferably 1100°C or lower, even more preferably 1075°C or lower, and particularly preferably 1050°C or lower. The devitrification temperature is the lowest temperature at which, when heated and melted glass is allowed to cool naturally, no crystals with a long side or major axis of 1 μm or more are observed on the surface or inside of the glass.

[0113] <Glass composition A3> The glass composition A3 is the same as the glass composition A described above, except that the alkaline earth metal component is more than 5% and not more than 50% and the B2O3 is 15% or more. The components of this glass composition A3 will be described below. Components not described in this glass composition A3 are the same as those in the glass composition A described above, and therefore will not be described again.

[0114] SiO2 is a glass-forming component that provides high strength and crack resistance to glass and improves the stability and chemical durability of glass. The SiO2 content is preferably 5% or more and 44% or less. When the SiO2 content is 5% or more and the viscosity of glass is 10 1The temperature T1 at which the viscosity reaches dPa·s can be set within a preferred range. The SiO2 content is preferably 5% or more, more preferably 10% or more, even more preferably 12% or more, even more preferably 13% or more, still more preferably 14% or more, and particularly preferably 15% or more. On the other hand, when the SiO2 content is 44% or less, components for achieving a high refractive index can be added. The SiO2 content is more preferably 37% or less, even more preferably 30% or less, even more preferably 23% or less, even more preferably 20% or less, and particularly preferably 17% or less.

[0115] B2O3 is a glass-forming component and is an essential component. B2O3 lowers the Tg, improves mechanical properties such as glass strength and crack resistance, and lowers the devitrification temperature. However, a high B2O3 content tends to lower the refractive index. Therefore, the B2O3 content is preferably 15% or more and 40% or less. The B2O3 content is more preferably 35% or less, even more preferably 32% or less, still more preferably 29% or less, even more preferably 27% or less, and particularly preferably 26% or less. The B2O3 content is more preferably 18% or more, even more preferably 21% or more, still more preferably 23% or more, and particularly preferably 24% or more.

[0116] SiO2 and B2O3 are glass-forming components that improve the stability of glass, and their combined content is 30% to 70%. A high combined content of SiO2 and B2O3 lowers the devitrification temperature of the glass, making it easier to manufacture. Therefore, the combined content of SiO2 and B2O3 is 30% or more, preferably 32% or more, more preferably 34% or more, even more preferably 36% or more, and particularly preferably 39% or more. On the other hand, reducing the combined content of SiO2 and B2O3 can improve the refractive index. Therefore, when a particularly high refractive index is required, the combined content is preferably 70% or less, more preferably 60% or less, even more preferably 50% or less, even more preferably 45% or less, and particularly preferably 42% or less.

[0117] When B2O3 is contained, if the ratio of SiO2 to B2O3, SiO2 / B2O3, is large, the glass is prone to devitrification. Therefore, when B2O3 is contained, SiO2 / B2O3 is preferably 5.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, still more preferably 1.5 or less, and particularly preferably 1.0 or less.

[0118] TiO2, Ta2O5, WO3, Nb2O5, ZrO2, and Ln2O3 (Ln is at least one element selected from the group consisting of Y, La, Gd, Yb, and Lu) are high-refractive-index components that increase the refractive index of glass. The total content of these components is preferably 30% to 55%. When a particularly high refractive index is required, the total content is preferably 33% or more, more preferably 35% or more, even more preferably 36% or more, even more preferably 37% or more, and particularly preferably 38% or more. On the other hand, if the content of these high-refractive-index components increases, devitrification becomes more likely. For applications requiring a lower surface roughness (Ra), the total content of these components is more preferably 50% or less, even more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less.

[0119] The total content of alkali metal components (Li2O + Na2O + K2O) is 0% or more and 10% or less. Increasing the amount of these alkali metal components can lower Tg. However, if the amount of Li2O + Na2O + K2O is too high, T1 tends to be low, the viscosity curve becomes steep, and manufacturing characteristics deteriorate. On the other hand, if the amount of Li2O + Na2O + K2O is too low, T1 tends to be high, the dissolution temperature increases, and coloration may occur. Therefore, when Li2O + Na2O + K2O is contained, it is preferably 0.5% or more and 10% or less. Li2O + Na2O + K2O is more preferably 1% or more, even more preferably 1.5% or more, even more preferably 2% or more, and particularly preferably 3% or more. Furthermore, Li2O + Na2O + K2O is preferably 6% or less, more preferably 4% or less, even more preferably 3% or less, and particularly preferably 2% or less.

[0120] The Li2O content is 0% or more and 10% or less. When Li2O is contained, the content is 0.2% or more and 10% or less. The inclusion of Li2O can improve strength (Kc) and crack resistance (CIL). When the optical glass of the present invention contains Li2O, its content is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, and particularly preferably 2% or more. On the other hand, if the Li2O content is too high, devitrification is likely to occur. When devitrification is particularly problematic, the Li2O content is preferably 6% or less, more preferably 3% or less, even more preferably 1% or less, and particularly preferably 0.1% or less. When the optical glass of this embodiment is chemically strengthened, the Li2O content is preferably 3.0% or more, more preferably 6.0% or more, even more preferably 9.0% or more, and particularly preferably 11.0% or more.

[0121] CaO is a component that suppresses devitrification, but if the amount of CaO is too high, crack resistance tends to decrease. Therefore, the CaO content is preferably 0% or more and 25% or less. The CaO content is more preferably 20% or less, even more preferably 17% or less, even more preferably 14% or less, still more preferably 13% or less, even more preferably 12% or less, and particularly preferably 11.5% or less. Furthermore, the CaO content is more preferably 4% or more, even more preferably 8% or more, even more preferably 10% or more, and particularly preferably 11% or more.

[0122] SrO is a component that improves the meltability of glass, suppresses devitrification, and adjusts the optical constants of glass. On the other hand, a large amount of SrO actually promotes devitrification. Therefore, the SrO content is preferably 0% or more and 20% or less. The SrO content is more preferably 15% or less, even more preferably 12% or less, still more preferably 10% or less, even more preferably 9% or less, and particularly preferably 8% or less. Furthermore, the SrO content is more preferably 2% or more, even more preferably 5% or more, and particularly preferably 7% or more.

[0123] If the total amount of MgO, CaO, and SrO is too high, the glass is more likely to devitrify. Therefore, the total amount of MgO, CaO, and SrO is preferably 30% or less, more preferably 25% or less, even more preferably 22% or less, even more preferably 21% or less, still more preferably 20% or less, and particularly preferably 19.5% or less.

[0124] BaO is a component that suppresses devitrification, but if the amount of BaO is large, the density tends to increase. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The BaO content is more preferably 20% or less, even more preferably 15% or less, even more preferably 11% or less, still more preferably 9% or less, and particularly preferably 8% or less. Furthermore, the BaO content is more preferably 2% or more, even more preferably 5% or more, and particularly preferably 7% or more.

[0125] The total content of alkaline earth metal components (MgO + CaO + SrO + BaO) is 5% or more and 50% or less. A total content of 50% or less is preferable because it can prevent devitrification of the glass. It is more preferably 40% or less, even more preferably 35% or less, even more preferably 32% or less, even more preferably 30% or less, even more preferably 29% or less, even more preferably 28% or less, and particularly preferably 20% or less. A total content of 5% or more is preferable because it can improve the meltability of the glass. It is more preferably 10% or more, even more preferably 15% or more, even more preferably 20% or more, even more preferably 25% or more, and particularly preferably 26% or more.

[0126] The specific gravity can be reduced by setting the ratio of BaO (BaO / (MgO+CaO+SrO+BaO)) in the alkaline earth metal components (MgO+CaO+SrO+BaO) to 0.5 or less. It is preferably 0.45 or less, more preferably 0.42 or less, even more preferably 0.40 or less, and particularly preferably 0.35 or less. Increasing the proportion of BaO in the alkaline earth metal components can lower the devitrification temperature and improve manufacturing characteristics. When manufacturing characteristics are particularly important, it is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.25 or more, and particularly preferably 0.3 or more.

[0127] As the total amount of alkali metal components (Li2O + Na2O + KO) and alkaline earth metal components (MgO + CaO + SrO + BaO) increases, the Tg of the glass tends to decrease. Therefore, the total amount of alkali metal components and alkaline earth metal components is preferably 30% or less, more preferably 29% or less, even more preferably 28% or less, and particularly preferably 27.5% or less.

[0128] TiO2 is a component that increases the refractive index of glass and increases the dispersion of glass, and its content is 0% or more and 50% or less. When TiO2 is contained, its content is preferably 10% or more, more preferably 15% or more, even more preferably 17% or more, even more preferably 19% or more, still more preferably 20% or more, and particularly preferably 20.5% or more. On the other hand, if the amount of TiO2 is too high, coloration is likely to occur and transmittance decreases. Therefore, when transmittance is particularly required, the TiO2 content is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 25% or less, still more preferably 23% or less, even more preferably 22% or less, and particularly preferably 21% or less.

[0129] When B2O3 is contained, if the ratio of TiO2 to B2O3 (TiO2 / B2O3) is large, the melting temperature must be raised, which makes it easier for Ti to be reduced, causing the glass to become colored and the transmittance to decrease. Therefore, when B2O3 is contained, TiO2 / B2O3 is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, even more preferably 2.0 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, and particularly preferably 1.0 or less.

[0130] Nb2O5 increases the refractive index of the glass and also increases the Abbe number (v d The content of Nb2O5 is 0% or more and 35% or less. The content of Nb2O5 is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 1.5% or more, still more preferably 2.0% or more, and particularly preferably 2.5% or more. In addition, if the amount of Nb2O5 is too much, devitrification occurs easily. Therefore, for applications requiring a lower surface roughness Ra, the amount is preferably 20% or less, more preferably 10% or less, even more preferably 5% or less, and particularly preferably 3% or less.

[0131] As the total content of TiO2, WO3, and Nb2O5 decreases, the refractive index of the glass decreases. Therefore, the total content of TiO2, WO3, and Nb2O5 is preferably 10% or more and 50% or less. It is more preferably 14% or more, even more preferably 18% or more, even more preferably 22% or more, and particularly preferably 23% or more. On the other hand, as the total content of TiO2, WO3, and Nb2O5 increases, devitrification becomes more likely. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, and particularly preferably 25% or less.

[0132] ZrO2 is a component that increases the refractive index of glass and enhances the chemical durability of glass, and its content is 0% or more and 20% or less. Inclusion of ZrO2 can improve crack resistance. When ZrO2 is contained, its content is more preferably 1% or more, even more preferably 2% or more, even more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if the ZrO2 content is too high, devitrification tends to occur. Therefore, when manufacturing properties are particularly important, the ZrO2 content is more preferably 15% or less, even more preferably 10% or less, even more preferably 6% or less, and particularly preferably 5% or less.

[0133] ZnO is a component that improves mechanical properties such as strength and crack resistance of glass, and its content is 0% or more and 15% or less. When ZnO is contained, its content is more preferably 0.3% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, since a large amount of ZnO makes devitrification more likely, the ZnO content is more preferably 10% or less, even more preferably 5% or less, even more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0134] La2O3 is a component that improves the refractive index of glass, and its content is 0% or more and 35% or less. When La2O3 is contained, its content is preferably 2% or more, more preferably 3% or more, even more preferably 4% or more, even more preferably 4.5% or more, and particularly preferably 5% or more. On the other hand, if the amount of La2O3 is too high, the mechanical properties deteriorate and the devitrification temperature rises. Therefore, when mechanical properties and manufacturing characteristics are important, the La2O3 content is preferably 30% or less. 25% or less is more preferable, 20% or less is even more preferable, 15% or less is even more preferable, 10% or less is even more preferable, 7% or less is even more preferable, and 6% or less is particularly preferable.

[0135] When the ratio of the total amount of Nb2O5, TiO2, WO3, and Ta2O5 to the total amount of La2O3, Gd2O3, Y2O3, and Yb2O3 (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) becomes large, the glass becomes colored and transmittance tends to decrease. Therefore, (Nb2O5 + TiO2 + WO3 + Ta2O5) / (La2O3 + Gd2O3 + Y2O3 + Yb2O3) is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 7.0 or less, even more preferably 6.0 or less, still more preferably 5.5 or less, and particularly preferably 5.0 or less. On the other hand, as (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) becomes smaller, the Tg of the glass tends to decrease. Therefore, for applications requiring high heat resistance, (Nb2O5+TiO2+WO3+Ta2O5) / (La2O3+Gd2O3+Y2O3+Yb2O3) is preferably 0.5 or greater, more preferably 1.0 or greater, even more preferably 2.0 or greater, even more preferably 3.0 or greater, and particularly preferably 4.0 or greater.

[0136] The optical glass obtained with the glass composition A3 has a high refractive index (n d ) has a refractive index (n d ) is 1.81 or more. This optical glass is suitable for use in wearable devices in terms of widening the image angle, increasing brightness and contrast, improving light guide characteristics, and facilitating the processing of diffraction gratings. It is also suitable for use as a small imaging glass lens with a wide imaging angle for applications such as in-vehicle cameras and visual sensors for robots, as it allows for capturing images of a wider range in a smaller size. This refractive index (n d ) is preferably 1.820 or more, more preferably 1.830 or more, even more preferably 1.835 or more, even more preferably 1.840 or more, still more preferably 1.845 or more, and particularly preferably 1.850 or more. On the other hand, the refractive index (n d Glass with a refractive index (n ) exceeding 1.96 tends to have a high density and a high devitrification temperature. In particular, when low density of optical glass is important, the refractive index (n d) is preferably 1.92 or less, more preferably 1.90 or less, even more preferably 1.89 or less, even more preferably 1.88 or less, even more preferably 1.87 or less, even more preferably 1.86 or less, even more preferably 1.855 or less, and still more preferably 1.853 or less.

[0137] In addition, the optical glass obtained with glass composition A3 has a density of 3.3 g / cm 3 More than 5.4g / cm 3 This optical glass has a density (d) of 5.2 g / cm or less. By having a density in the above range, when used in wearable devices, it can provide a comfortable fit for the user, and when used in in-vehicle cameras, visual sensors for robots, etc., it can reduce the weight of the entire device. This density (d) is preferably 5.2 g / cm. 3 More preferably, it is 5.0 g / cm or less. 3 or less, more preferably 4.6 g / cm 3 or less, more preferably 4.2 g / cm 3 or less, more preferably 4.1 g / cm 3 or less, more preferably 4.0 g / cm 3 The following is the result. On the other hand, to make the surface of optical glass less susceptible to scratches, the density (d) should be 3.6 g / cm 3 More preferably, it is 3.7 g / cm or more. 3 More preferably, 3.8 g / cm 3 or more, and even more preferably 3.9 g / cm 3 More preferably, 3.95 g / cm 3 That's all.

[0138] Furthermore, this optical glass has a devitrification temperature of 1300°C or lower. Such properties allow for suppression of devitrification of the glass during molding, resulting in good moldability. The devitrification temperature is more preferably 1275°C or lower, even more preferably 1240°C or lower, even more preferably 1225°C or lower, even more preferably 1200°C or lower, even more preferably 1175°C or lower, even more preferably 1150°C or lower, even more preferably 1100°C or lower, even more preferably 1050°C or lower, even more preferably 1025°C or lower, and particularly preferably 1020°C or lower. The devitrification temperature is the lowest temperature at which, when heated and melted glass is allowed to cool naturally, no crystals with a long side or major axis of 1 μm or more are observed on the surface or inside the glass.

[0139] [Method of manufacturing optical glass and glass molded body] The optical glass of the present invention is manufactured, for example, as follows. First, raw materials are weighed and mixed uniformly to obtain the desired glass composition. The resulting mixture is placed in a platinum crucible, a quartz crucible, or an alumina crucible for rough melting. The mixture is then placed in a gold crucible, a platinum crucible, a platinum alloy crucible, a tempered platinum crucible, or an iridium crucible and melted at a temperature of 1200 to 1400°C for 2 to 10 hours. After homogenization and bubble removal by degassing, stirring, or the like, the mixture is poured into a mold and slowly cooled. This produces the optical glass of the present invention.

[0140] Furthermore, this optical glass can also be made into a glass plate by forming molten glass into a plate shape using a molding method such as a float method, a fusion method, or a roll-out method. Alternatively, the molten glass can be formed into a block shape and then made into a glass plate using a redraw method or the like. Furthermore, a glass molded body can be produced using, for example, reheat press molding or precision press molding. That is, a lens preform for mold press molding can be produced from the optical glass, and this lens preform can be reheat press molded and then polished to produce a glass molded body, or a lens preform produced by polishing can be precision press molded to produce a glass molded body. Note that the means for producing a glass molded body are not limited to these means.

[0141] The optical glass of the present invention produced as described above preferably has 10 or less residual bubbles per kg (10 / kg), more preferably 7 or less bubbles, even more preferably 5 or less bubbles, and particularly preferably 3 or less bubbles. When a glass plate is formed by the above method, a bubble-free glass plate can be efficiently formed if the residual bubbles are 10 or less bubbles / kg. Furthermore, when the diameter of the smallest circle that can contain a residual bubble is defined as the size of each residual bubble, the size of each residual bubble is preferably 80 μm or less, more preferably 60 μm or less, even more preferably 40 μm or less, and particularly preferably 20 μm or less.

[0142] Furthermore, when the diameter is defined as the longitudinal length L1 of the residual bubbles, and the length of the line perpendicular to the diameter that is the maximum length of the residual bubbles is defined as the horizontal length L2 of the residual bubbles, the shape of the residual bubbles can be expressed as an aspect ratio of L2 / L1, preferably 0.90 or more, more preferably 0.92 or more, and even more preferably 0.95 or more. When L2 / L1 is 0.90 or more, the residual bubbles are close to perfect circles (spheres). Even if residual bubbles are present, the glass strength is less likely to decrease compared to elliptical residual bubbles, and cracks originating from residual bubbles can be suppressed when producing a glass plate. Furthermore, even if residual bubbles are present on the glass substrate, the anisotropic scattering of light incident on the glass plate is less likely compared to elliptical residual bubbles. The size and shape of the residual bubbles are obtained from measurements using a laser microscope (Keyence Corporation: VK-X100).

[0143] Optical members such as glass plates and glass molded bodies produced in this manner are useful for various optical elements, and are particularly suitable for (1) light guides, filters, lenses, etc. used in wearable devices, such as projector-equipped glasses, eyeglass-type and goggle-type displays, virtual reality and augmented reality display devices, and virtual image display devices, and (2) lenses and cover glass, etc. used in vehicle-mounted cameras and robot visual sensors. They are also suitable for applications exposed to harsh environments, such as vehicle-mounted cameras. They are also suitable for applications such as glass substrates for organic electroluminescence (EL) devices, substrates for wafer-level lens arrays, substrates for lens units, substrates for lens formation by etching, and optical waveguides.

[0144] The optical glass of the present embodiment described above has a high refractive index and low density, and has good manufacturing properties, making it suitable for use in wearable devices, vehicles, and robots. Furthermore, optical components having an antireflection coating formed on the main surface of this optical glass, which is a 4-10 layer dielectric multilayer film formed by alternately laminating low-refractive-index films such as SiO2 and high-refractive-index films such as TiO2, are also suitable for use in wearable devices, vehicles, and robots. [Example]

[0145] The raw materials were weighed out so as to obtain the chemical compositions (mol % calculated as oxides) shown in Tables 1 to 9. The raw materials used were all selected from high-purity raw materials used in ordinary optical glass, such as the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds, as raw materials for each component.

[0146] The weighed raw materials were mixed uniformly and placed in a platinum crucible with an internal volume of approximately 300 mL, melted at approximately 1300°C for approximately 2 hours, refined, stirred, and then held at 1300°C for 0.5 hours, poured into a rectangular mold preheated to approximately 650°C, measuring 50 mm in length and 100 mm in width, and slowly cooled at a rate of approximately 1°C / min to obtain samples of Examples 1 to 85. Examples 1 to 80 are working examples, and Examples 81 to 85 are comparative examples.

[0147] [evaluation] For each sample obtained above, the refractive index (n d ), density (d), devitrification temperature, viscosity (the viscosity of glass is 10 1 The temperature T1) at which the viscosity becomes dPa·s was measured as follows. The results are shown in Tables 1 to 9.

[0148] Refractive index (n d ): The sample glass was processed into a triangular prism with a side length of 30 mm and a thickness of 10 mm, and the refractive index was measured using a refractometer (Kalnew, device name: KPR-2000). Density (d): Measured in accordance with JIS Z8807 (1976, measurement method by weighing in liquid). Devitrification temperature: Approximately 5 g of sample was placed in a platinum dish and held at temperatures between 1000°C and 1400°C in 5°C increments for one hour. After allowing the sample to cool naturally, the presence or absence of crystal precipitation was observed under a microscope, and the lowest temperature at which no crystals with a long side or major axis of 1 μm or more were observed was taken as the devitrification temperature.

[0149] Temperature T1: According to the method specified in ASTM C 965-96, the viscosity of the glass is measured using a rotational viscometer. 1 The temperature T1 (°C) at which the viscosity reached dPa·s was measured.

[0150] Glass transition temperature (Tg): A value measured using a differential thermal dilatometer (TMA) according to JIS R3103-3 (2001). Young's modulus (E): Measured for a plate-shaped sample of 20 mm x 20 mm x 1 mm using an ultrasonic precision thickness gauge (OLYMPAS, MODEL 38DL PLUS) (unit: GPa).

[0151] LTV: The thickness of the glass substrate was measured at 3 mm intervals using a non-contact laser displacement meter (Nano Metro manufactured by Kuroda Precision Industries) for a plate-shaped sample of 50 mm x 50 mm x 1 mm, and the LTV was calculated. Warpage: The heights of the two main surfaces of the glass substrate were measured at 3 mm intervals using a non-contact laser displacement meter (Nano Metro manufactured by Kuroda Precision Industries) for disk-shaped samples with a diameter of 8 inches x 1 mm and a diameter of 6 inches x 1 mm, and the warpage was calculated using the method described above with reference to Figure 1. Surface roughness (Ra): This is the value measured over a 10 μm×10 μm area of ​​a 20 mm×20 mm×1 mm plate-shaped sample using an atomic force microscope (AFM) (manufactured by Oxford Instruments). Abbe number (ν d ): Using the sample used in the refractive index measurement above, νd=(n d -1) / (n F -n C ) is calculated by n d is the helium d line, n F is the hydrogen F line, and n C is the refractive index for the hydrogen C line. These refractive indices were also measured using the refractometer described above. Coefficient of thermal expansion (α): The coefficient of linear thermal expansion was measured in the range of 50 to 350°C using a differential thermal dilatometer (TMA), and the average coefficient of linear thermal expansion in the range of 50 to 350°C was determined according to JIS R3102 (1995).

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

[0155] [Table 4]

[0156] [Table 5]

[0157] [Table 6]

[0158] [Table 7]

[0159] [Table 8]

[0160] [Table 9]

[0161] The optical glasses of the above examples (Examples 1 to 80) all have a refractive index (n d ) is 1.81 or more, and has a high refractive index. 3 The viscosity of the glass is low at 10 1 The temperature T1 at which the glass reaches dPa·s is 900-1200°C, which means that it has good manufacturing properties. Furthermore, the devitrification temperature is 1300°C or less, which means that it has good manufacturing properties. Therefore, it is suitable for use as optical glass in wearable devices, in-vehicle cameras, and robot vision systems.

[0162] On the other hand, the glasses of Examples 81 and 84, which are comparative examples, have a devitrification temperature higher than 1300°C and are inferior in manufacturing properties. The glasses of Examples 81, 82, and 83 have a refractive index (nd) lower than 1.81. The glass of Example 85 has a Si content lower than 5 mol%.

[0163] The optical glass obtained from the glass obtained by melting the glass composition of each of the above Examples (Examples 1 to 80) has good manufacturing characteristics because the temperature T1 is 900 to 1200°C, and the size and number of residual bubbles are small, resulting in a glass plate free of defects such as bubbles, foreign matter, striae, and phase separation. Therefore, by forming a sample of the above size, optical glass can be obtained with an LTV value of 2 μm or less, a warpage value (for a 6-inch diameter circular glass plate) of 30 μm or less, and an Ra value of 2 nm or less. Furthermore, since the devitrification temperature is 1300°C or less, devitrification is suppressed, so it is believed that an LTV value of 1.5 μm or less, a warpage value (for a 6-inch diameter circular glass plate) of 18 μm or less, and an Ra value of 1 nm or less can be achieved.

[0164] When three types of glass plates free of the above-mentioned defects of this example were precision polished, the LTV values ​​were 1.0, 1.2, and 1.2 μm, the warpage values ​​were 45, 32, and 38, and the Ra values ​​were 0.198, 0.284, and 0.266. Therefore, by precision polishing the glass plates free of the above-mentioned defects of this example, it is possible to obtain optical glass with an LTV value of 2 μm or less, a warpage value of 50 μm or less, and an Ra value of 2 nm or less.

[0165] When chemically strengthening the glass of the present invention, for example, the glass can be immersed for 30 minutes in a melt obtained by heating sodium nitrate to 400° C. to perform chemical strengthening treatment, thereby obtaining tempered glass.

[0166] As described above, the optical glass of the present invention has a high refractive index and low density, and also has good manufacturing properties, making it suitable for use in wearable devices, on-board equipment, robots, etc. Optical components formed with an antireflection coating consisting of a 4 to 10-layer dielectric multilayer film formed by alternately laminating low-refractive-index films such as SiO2 and high-refractive-index films such as TiO2 on the optical glass of the above examples are also suitable for use in wearable devices, on-board equipment, and robots.

[0167] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on August 31, 2018 (Patent Application No. 2018-163582) and November 21, 2018 (Patent Application No. 2018-218577), the contents of which are incorporated herein by reference.

Claims

1. 25 cm of one main surface ２ A glass plate for a light guide plate having an LTV of 2 μm or less, Refractive index (n ｄ ) is 1.88 to 2.10, In mole percent based on oxides, SiO ２ The content ratio of is 10% to 30%, B ２ O ３ The content is 5% to 23%, The content of BaO is 0% to 15%; The content of ZnO is 0% to 5%; ZrO ２ The content is 5% to 10%; TiO ２ The content ratio is 10% to 34%, Nb ２ O ５ The content is 3% to 6%; La ２ O ３ The content ratio of is 10% to 30%, Gd ２ O ３ The content is 1% to 5%; Y ２ O ３ The content is 0% to 5%; B ２ O ３ SiO ２ The ratio of SiO ２ / B ２ O ３ is 3.0 or less, SiO ２ and B ２ O ３ ZrO relative to the total amount of ２ and Ta ２ O ５ and Nb ２ O ５ The ratio of the total amount of ZrO ２ +Ta ２ O ５ +Nb ２ O ５ ) / (SiO ２ +B ２ O ３ ) is 0.6 or less, The density (d) is 6.0 g / cm 3 or less, the temperature T 1 at which the viscosity of the glass reaches 10 1 dPa·s is 900 to 1200°C; The devitrification temperature is 1300°C or less. Glass plate for light guide plates.

2. 25 cm of one main surface ２ A glass plate for a light guide plate having an LTV of 2 μm or less, Refractive index (n ｄ ) is 1.89 to 1.93, In mole percent based on oxides, The content of alkaline earth metal components (MgO + CaO + SrO + BaO) is 19% to 25%; SiO ２ The content ratio is 28% to 34%, B ２ O ３ The content is 5% to 12%, The content of BaO is 6% to 11%; The content of ZnO is 0% to 2%, ZrO ２ The content is 1% to 5%; TiO ２ The content ratio is 17% to 23%, Nb ２ O ５ The content is 4% to 7%; La ２ O ３ The content is 4% to 10%; Gd ２ O ３ The content is 0% to 5%; the total amount of alkali metal components and alkaline earth metal components is 30% or less; La ２ O ３ and G-d ２ O ３ and Y ２ O ３ and Yb ２ O ３ Nb relative to the total amount of ２ O ５ and TiO ２ and W.O. ３ and Ta ２ O ５ The ratio of the total amount of Nb ２ O ５ + TiO ２ +WO ３ +Ta ２ O ５ ) / (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ +Yb ２ O ３ ) is 2.0 to 5.0, The density (d) is 6.0 g / cm 3 or less, the temperature T 1 at which the viscosity of the glass reaches 10 1 dPa·s is 900 to 1200°C; The devitrification temperature is 1300°C or less. Glass plate for light guide plates.

3. 25 cm of one main surface ２ A glass plate for a light guide plate having an LTV of 2 μm or less, Refractive index (n ｄ ) is 1.99 to 2.06, In mole percent based on oxides, SiO ２ The content is 7% to 12%, B ２ O ３ The content ratio is 18% to 25%, The content of BaO is 0% to 4%; The content of ZnO is 0% to 2%, ZrO ２ The content is 5% to 8%; TiO ２ The content is 25% to 34%; Nb ２ O ５ The content is 3% to 6%; La ２ O ３ The content ratio is 15% to 25%, Gd ２ O ３ The content is 0% to 5%; Y ２ O ３ The content is 2.5% to 5%, B ２ O ３ SiO ２ The ratio of SiO ２ / B ２ O ３ is 3.0 or less, SiO ２ and B ２ O ３ ZrO relative to the total amount of ２ and Ta ２ O ５ and Nb ２ O ５ The ratio of the total amount of ZrO ２ +Ta ２ O ５ +Nb ２ O ５ ) / (SiO ２ +B ２ O ３ ) is 0.6 or less, The density (d) is 6.0 g / cm 3 or less, the temperature T 1 at which the viscosity of the glass reaches 10 1 dPa·s is 900 to 1200°C; The devitrification temperature is 1300°C or less. Glass plate for light guide plates.

4. 25 cm of one main surface ２ A glass plate for a light guide plate having an LTV of 2 μm or less, Refractive index (n ｄ ) is 1.94 to 2.10, Density (d) is 4.0 to 5.2 g / cm ３ and In mole percent based on oxides, SiO ２ The content is 9% to 20%, B ２ O ３ The content ratio is 12% to 22%, The content of BaO is 0.5% to 15%; The content of ZnO is 0.5% to 5%; ZrO ２ The content is 3% to 10%; TiO ２ The content ratio is 28% to 37%, Nb ２ O ５ The content is 2.5% to 6%, La ２ O ３ The content is 10% to 18%; Gd ２ O ３ The content is 1% to 5%; Y ２ O ３ The content is 0% to 5%; Li ２ The content of O is 0% to 4%, The content of CaO is 0% to 6%; The content of SrO is 0% to 4%; B ２ O ３ SiO ２ The ratio of SiO ２ / B ２ O ３ is 3.0 or less, SiO ２ and B ２ O ３ ZrO relative to the total amount of ２ and Ta ２ O ５ and Nb ２ O ５ The ratio of the total amount of ZrO ２ +Ta ２ O ５ +Nb ２ O ５ ) / (SiO ２ +B ２ O ３ ) is 0.6 or less, the temperature T 1 at which the viscosity of the glass reaches 10 1 dPa·s is 900 to 1200°C; The devitrification temperature is 1300°C or less. Glass plate for light guide plates.

5. The glass plate for light guide plates according to any one of claims 1 to 4, having a Young's modulus (E) of 60 GPa or more.

6. Abbe number (v ｄ ) is 18 or more and 30 or less, and the thermal expansion coefficient α at 50 to 350°C is 80 to 95 × 10 －７ The glass plate for a light guide plate according to any one of claims 1 to 5, wherein the glass plate has a viscosity of 1000 saturates.

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