阅读说明：本技术 光学玻璃和光学部件 (Optical glass and optical member ) 是由 安间伸一 北冈贤治 于 2019-08-27 设计创作，主要内容包括：本发明提供一种光学玻璃和使用该光学玻璃的光学部件,该光学玻璃的折射率(n-d)为1.81～2.15,密度为6.0g/cm～3以下,玻璃的粘度成为10～1dPa·s时的温度T-1为900～1200℃,失透温度为1300℃以下,以氧化物基准的摩尔％表示,SiO-2的含有比率为5～44％。(The invention provides an optical glass and an optical component using the same, the refractive index (n) of the optical glass d )1.81 to 2.15, and a density of 6.0g/cm 3 The viscosity of the glass is 10 1 Temperature T at dPa · s 1 Is 900 to 1200 ℃ lossA permeation temperature of 1300 ℃ or lower, expressed in mol% based on oxides, SiO 2 The content ratio of (B) is 5 to 44%.)

1. An optical glass characterized in that,

refractive index n_dIs 1.81 to 2.15 percent,

the density d is 6.0g/cm³In the following, the following description is given,

the viscosity of the glass became 10¹Temperature T at dPa · s₁The temperature is 900-1200 ℃,

the devitrification temperature is below 1300 ℃,

expressed in mol% based on oxide, SiO₂The content ratio of (B) is 5 to 44%.

2. The optical glass according to claim 1, wherein the glass transition temperature Tg is 600 ℃ or higher.

3. The optical glass according to claim 1 or 2, wherein the glass contains 30 to 80% of TiO selected from the group consisting of TiO, in mol% based on an oxide₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃At least 1 kind of (A), and SiO in a total amount of 20 to 70%₂And B₂O₃When MgO, CaO, SrO, and BaO, which are alkaline earth metal components, are contained, the content ratio of BaO in the alkaline earth metal components is 0.5 or less, and Ln is at least 1 selected from Y, La, Gd, Yb, and Lu.

4. The optical glass according to any one of claims 1 to 3, wherein a viscosity at a devitrification temperature, i.e., a devitrification viscosity, is 0.4 or more in log η.

5. The optical glass according to any one of claims 1 to 4, wherein the Young's modulus E is 60GPa or more.

6. The optical glass according to any one of claims 1 to 5, wherein Abbe number v_d60 or less, and 50 to 150 x10 of a coefficient of thermal expansion alpha at 50 to 350 DEG C^-7/K。

7. The optical glass according to any one of claims 1 to 6, wherein the optical glass is in the form of a plate having a thickness of 0.01 to 2 mm.

8. The optical glass according to any one of claims 1 to 7, wherein the area of one main surface is 8cm²The above.

9. The optical glass according to any one of claims 1 to 8, wherein the opposed main surfaces are polished on both sides to make an area of one main surface 25cm²The LTV of the glass substrate is 2 μm or less.

10. The optical glass according to any one of claims 1 to 9, wherein when a circular glass plate having a diameter of 8 inches is produced, the warpage of one main surface is 50 μm or less.

11. The optical glass according to any one of claims 1 to 10, wherein the surface roughness Ra is 2nm or less.

12. An optical member comprising the plate-like optical glass according to any one of claims 9 to 11.

13. The optical member according to claim 12, wherein an antireflection film is provided on a surface of the plate-shaped optical glass.

Technical Field

The present invention relates to an optical glass and an optical member.

Background

As glasses used for wearable devices, for example, glasses with a projector, glasses-type or goggle-type displays, virtual reality augmented reality display devices, virtual image display devices, and the like, high refractive indexes are required from the viewpoints of widening the angle of an image, increasing brightness and contrast, improving light guiding characteristics, improving the ease of processing of diffraction gratings, and the like. In addition, conventionally, imaging glass lenses having a small size and a wide imaging angle of view have been used for applications such as in-vehicle cameras and robot vision sensors, and such imaging glass lenses are required to have a high refractive index in order to achieve a smaller size and a wider imaging range.

As the optical glass used for the above applications, weight reduction is required for automobiles and robots in order to make the wearing feeling of users more ideal, and density reduction is required for reducing the weight of the entire device. In addition, if the use in the external environment is considered, it is also required that the surface deterioration and the deterioration due to chemicals such as acid rain, a detergent used in cleaning, and wax are reduced.

Among these, for example, the following attempts have been made with respect to a glass lens for vehicle mounting: by using a lens glass material for an in-vehicle camera having a predetermined acid resistance, the refractive index and strength are improved, and the acid resistance and water resistance are improved (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-256446

Disclosure of Invention

However, in the case of a composition having a high refractive index, a heavy metal oxide is often used as a glass component for increasing the refractive index. Therefore, in general, the density of the high-refractive-index glass increases.

Further, the wearable device may be produced by a molding method such as a float method, a melting method, or a roll-out method, which is efficient in production, using glass molded into a plate shape.

In addition, when used as an optical member, the visible light transmittance is also an important parameter, and in the case of a high refractive index glass, when melted at a high temperature, the visible light transmittance may be particularly lowered on the short wavelength side. On the other hand, if the viscosity curve is steep, viscosity control at the time of production becomes difficult.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical glass having a high refractive index, a low density, and good production characteristics.

The optical glass of the present invention is characterized by a refractive index (n)_d)1.81 to 2.15, and a density of 6.0g/cm³The viscosity of the glass is 10¹Temperature T at dPa · s₁900 to 1200 ℃ and a devitrification temperature of 1300 ℃ or lower, expressed in mol% based on an oxide, of SiO₂The content ratio of (B) is 5 to 44%.

The optical member of the present invention is characterized by comprising the plate-like optical glass of the present invention.

Drawings

Fig. 1 is a sectional view for explaining warping of an optical glass.

Detailed Description

Embodiments of the optical glass and the optical member of the present invention will be described below.

The optical glass of the present invention has a predetermined refractive index (n) as described above_d) The density (d) and the melting property will be described in order.

The optical glass of the present invention has a high refractive index (n) in the range of 1.81 to 2.15_d). Due to the refractive index (n)_d)1.81 or more, and therefore the optical glass of the present invention is useful as an optical glass for a wearable deviceGlass is suitable for widening the angle of an image, increasing brightness and contrast, improving light guiding characteristics, and facilitating processing of a diffraction grating. Further, a small-sized imaging glass lens having a wide imaging angle, which is used for applications such as an in-vehicle camera and a robot vision sensor, is preferable because it is smaller and has a wider imaging range. The refractive index (n)_d) Preferably 1.85 or more, more preferably 1.88 or more, further preferably 1.91 or more, further preferably 1.94 or more, further preferably 1.97 or more, further preferably 1.99 or more, further preferably 2.00 or more.

On the other hand, refractive index (n)_d) A glass exceeding 2.15 tends to have a high density and a high devitrification temperature. In particular, when the density of the optical glass is regarded as high or low, the refractive index (n) is_d) Preferably 2.10 or less, more preferably 2.06 or less, further preferably 2.03 or less, further preferably 2.01 or less, further preferably 1.98 or less, further preferably 1.95 or less, further preferably 1.94 or less, further preferably 1.92 or less.

In addition, the optical glass of the present invention has a refractive index of 6.0g/cm³The following density (d). The optical glass of the present invention has a density in the above range, and therefore, when used in wearable equipment, the optical glass can provide a user with a satisfactory wearing feeling, and when used in an in-vehicle camera, a robot vision sensor, or the like, the optical glass can reduce the weight of the entire device. The density (d) is preferably 5.6g/cm³Hereinafter, more preferably 5.2g/cm³Hereinafter, more preferably 4.8g/cm³Hereinafter, more preferably 4.6g/cm³Hereinafter, more preferably 4.4g/cm³Hereinafter, more preferably 4.2g/cm³The following.

On the other hand, in the optical system of the present invention, the density (d) is preferably 3.3g/cm in order that the glass surface is not easily scratched³The above. The density (d) is more preferably 3.6g/cm³Above, more preferably 3.9g/cm³Above, more preferably 4.2g/cm³Above, more preferably 4.4g/cm³The above, further preferredIs selected to be 4.7g/cm³The above.

Further, the glass of the optical glass of the present invention has a viscosity of 10¹Temperature T at dPa · s₁Is in the range of 900-1200 ℃. T is₁The reference temperature for the melting property is the T of the glass₁If the refractive index is too high, the melting needs to be performed at a high temperature, and therefore, in the case of a high refractive index glass, the visible light transmittance may be particularly lowered on the short wavelength side. The T is₁Preferably 1180 ℃ or lower, more preferably 1150 ℃ or lower, still more preferably 1130 ℃ or lower, and still more preferably 1110 ℃ or lower.

On the other hand, if T₁If the viscosity is too low, the viscosity curve becomes steep, and it is difficult to control the viscosity during production. The optical glass of the present invention passes through T having the above range₁The manufacturing characteristics can be improved. The T is₁Preferably 950 ℃ or higher, more preferably 1000 ℃ or higher, further preferably 1050 ℃ or higher, further preferably 1080 ℃ or higher, further preferably 1100 ℃ or higher, and particularly preferably 1120 ℃ or higher.

The optical glass of the present invention has a devitrification temperature of 1300 ℃ or lower. With such characteristics, devitrification of the glass during molding can be suppressed, and the moldability is good. The devitrification temperature is more preferably 1275 ℃ or lower, still more preferably 1250 ℃ or lower, still more preferably 1225 ℃ or lower, still more preferably 1200 ℃ or lower, still more preferably 1175 ℃ or lower, still more preferably 1150 ℃ or lower, still more preferably 1125 ℃ or lower, still more preferably 1100 ℃ or lower, still more preferably 1075 ℃ or lower, and particularly preferably 1050 ℃ or lower. Here, the devitrification temperature is the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more are not visible on the surface and inside of the glass when the heated and melted glass is cooled by natural cooling.

In the optical glass of the present invention, the glass transition temperature (Tg) is preferably 600 ℃ or higher. The optical glass of the present invention has a Tg of 600 ℃ or higher, and thus can suppress deformation such as warpage in a process. The Tg is more preferably 630 ℃ or higher, still more preferably 660 ℃ or higher, still more preferably 690 ℃ or higher, still more preferably 720 ℃ or higher, and particularly preferably 750 ℃ or higher. When molding such as press molding or redraw molding is performed, Tg is preferably 800 ℃ or lower. More preferably 760 ℃ or lower, still more preferably 720 ℃ or lower, still more preferably 680 ℃ or lower, and particularly preferably 640 ℃ or lower. Tg can be measured, for example, by thermal expansion.

When the viscosity at the devitrification temperature (devitrification viscosity) η is expressed in units of dPa · s, the optical glass of the present invention preferably has a log η of 0.4 or more. With such characteristics, devitrification of the glass during molding can be suppressed, and the moldability is good. The viscosity at the devitrification temperature is more preferably 0.5 or more log η, still more preferably 0.6 or more log η, still more preferably 0.7 or more log η, and particularly preferably 0.8 or more log η.

The optical glass of the present invention preferably has an abbe number (v) of 60 or less_d). When the optical glass of the present invention is applied to a glass plate such as a light guide plate, the low v having the above range is used_dSince the optical design of the wearable device is facilitated and the chromatic aberration is also easily improved, high-definition images and videos can be reproduced. v. of_dMore preferably 50 or less, still more preferably 40 or less, still more preferably 38 or less, still more preferably 35 or less, yet more preferably 32 or less, and particularly preferably 30 or less.

The optical glass of the present invention preferably has an abbe number (v) of 15 or more_d). Specifically, when the optical glass of the present invention is applied to a glass plate such as a light guide plate, the high v having the above range is used_dThe refractive index matching with the resin coated on the surface is easily obtained. v. of_dMore preferably 18 or more, further preferably 21 or more, further preferably 23 or more, further preferably 25 or more, further preferably 27 or more, and particularly preferably 29 or more.

The optical glass of the present invention preferably has a thermal expansion coefficient (α) of 50 to 350 ℃ of 50 to 150 (x 10)^-7K) is added. If the amount of alpha is within the above range, the optical glass of the present invention is expansion-matched with the peripheral memberThe preparation is good. The lower limit of α is preferably 60(× 10)^-7/K) or more, more preferably 70(× 10)^-7More preferably 80(× 10) or more^-7More than or equal to/K), particularly preferably 90(× 10)^-7and/K) above.

In addition, if the optical glass of the present invention has α in the above range, cracking is less likely to occur during cooling, and thus the cooling rate can be increased. As a result, the difference (Tf-Tg) between the virtual temperature (Tf) and the glass transition temperature (Tg) of the optical glass can be set to 0 ℃ or higher, the structure of the glass can be made more sparse, and even if some impact is applied to the optical glass, the impact can be easily absorbed by the densification of the glass structure. As a result, the strength of the optical glass itself is improved, and damage due to dropping or the like can be suppressed. The upper limit of α is preferably 120(× 10)^-7/K) or less, more preferably 110(× 10)^-7Is preferably 100(× 10) or less, (/ K)^-7A value of 95 (. times.10) or less, particularly preferably 95 (. times.10)^-7and/K) below.

The optical glass of the present invention is preferably a glass plate having a thickness of 0.01 to 2 mm. When the thickness is 0.01mm or more, breakage of the optical glass during handling and processing can be suppressed. In addition, the deflection of the optical glass due to its own weight can be suppressed. The thickness is more preferably 0.1mm or more, still more preferably 0.3mm or more, and still more preferably 0.5mm or more. On the other hand, if the thickness is 2mm or less, the optical element using the optical glass can be made lightweight. The thickness is more preferably 1.5mm or less, still more preferably 1.0mm or less, and still more preferably 0.8mm or less.

In the case where the optical glass of the present invention is a glass plate, the area of one main surface is preferably 8cm²The above. If the area is 8cm²As described above, a plurality of optical elements can be arranged, and productivity is improved. The area is more preferably 30cm²Above, more preferably 170cm²Above, more preferably 300cm²Above, particularly preferably 1000cm²The above. On the other hand, if the area is 6500cm²Hereinafter, the handling of the glass plate becomes easy, and the breakage of the glass plate during handling and processing can be suppressed. The area is more excellentIs selected to be 4500cm²The thickness is more preferably 4000cm²Hereinafter, more preferably 3000cm²Hereinafter, particularly preferably 2000cm²The following.

In the case where the optical glass of the present invention is a glass plate, 25cm of one main surface²The LTV (Local Thickness Variation) of (2) is preferably 2 μm or less. By having a flatness in this range, a nanostructure having a desired shape can be formed on one main surface by using a stamping technique or the like, and desired light guiding properties can be obtained. In particular, ghost phenomenon and distortion due to the difference in optical path length in the light guide body can be prevented. The LTV is more preferably 1.8 μm or less, still more preferably 1.6 μm or less, still more preferably 1.4 μm or less, and particularly preferably 1.2 μm or less.

When the optical glass of the present invention is formed into a circular glass plate having a diameter of 8 inches, the warp is preferably 50 μm or less. If the warp of the glass plate is 50 μm or less, a nanostructure having a desired shape can be formed on one main surface by using a stamping technique or the like, and desired light guiding properties can be obtained. When a plurality of light guides are desired, a light guide having stable quality can be obtained. The warp of the glass substrate is more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 20 μm or less.

When a circular glass plate having a diameter of 6 inches is produced, the warp is preferably 30 μm or less. If the warp of the glass plate is 30 μm or less, a nanostructure having a desired shape can be formed on one main surface by using a stamping technique or the like, and desired light guiding properties can be obtained. When a plurality of light guides are desired, a light guide having stable quality can be obtained. The warp of the glass plate is more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less.

In addition, when a square glass plate having 6 inches on each side is produced, the warp is preferably 100 μm or less. If the warp of the glass plate is 100 μm or less, a nanostructure having a desired shape can be formed on one main surface by using a stamping technique or the like, and desired light guiding properties can be obtained. When a plurality of light guides are desired, a light guide having stable quality can be obtained. The warp of the glass plate is more preferably 70 μm or less, still more preferably 50 μm or less, still more preferably 35 μm or less, and particularly preferably 20 μm or less.

FIG. 1 is a sectional view of a glass sheet G1 made of the optical glass of the present invention. "warp" means a difference C between a maximum value B and a minimum value a of a distance in a direction perpendicular to a center line G1C of a glass sheet G1 from a reference line G1D of a glass sheet G1 in an arbitrary cross section passing through the center of one main surface G1F of the glass sheet G1 and being orthogonal to one main surface G1F of the glass sheet G1.

The intersection of the arbitrary perpendicular cross section and the one main surface G1F of the glass sheet G1 is defined as a bottom line G1A. The intersection of the arbitrary perpendicular cross section and the other main surface G1G of the glass sheet G1 is defined as an upper line G1B. Here, the center line G1C is a line connecting the centers of the glass sheets G1 in the sheet thickness direction. The center line G1C is calculated by determining the midpoint between the bottom line G1A and the upper line G1B with respect to the direction of laser irradiation described later.

Reference line G1D is determined as follows. First, the bottom line G1A is calculated based on the measurement method for eliminating the influence of its own weight. From the bottom line G1A, a straight line is obtained by the least square method. The obtained straight line is a reference line G1D. As a measuring method for eliminating the influence of the self weight, a known method can be used.

For example, the first main surface G1F of the glass sheet G1 is supported at 3 points, and the glass sheet G1 is irradiated with laser light by a laser displacement meter, and the heights of the first main surface G1F and the second main surface G1G of the glass sheet G1 from an arbitrary reference plane are measured.

Next, the glass sheet G1 was turned upside down, 3 points of the other main surface G1G opposed to 3 points supporting the one main surface G1F were supported, and the heights of the one main surface G1F and the other main surface G1G of the glass substrate G1 from an arbitrary reference plane were measured.

The influence of the self-weight is eliminated by averaging the heights of the respective measurement points before and after the inversion. For example, prior to inversion, the height of one major surface G1F is measured as above. After the glass sheet G1 was turned over, the height of the other main surface G1G was measured at a position corresponding to the measurement point of the one main surface G1F. Similarly, the height of the other major surface G1G was measured before inverting. After the glass sheet G1 was turned over, the height of one main surface G1F was measured at a position corresponding to the measurement point of the other main surface G1G.

The warpage can be measured, for example, using a laser displacement meter.

In the optical glass of the present invention, the surface roughness Ra of one main surface is preferably 2nm or less. By having Ra in this range, a nanostructure having a desired shape can be formed on one main surface by using a stamping technique or the like, and desired light guiding properties can be obtained. In particular, in the light guide, the light guide can suppress the diffuse reflection at the interface to prevent the ghost phenomenon and distortion. The Ra is more preferably 1.7nm or less, still more preferably 1.4nm or less, still more preferably 1.2nm or less, and particularly preferably 1nm or less. Here, the surface roughness Ra is an arithmetic average roughness defined by JIS B0601 (2001). In the present specification, the values are measured in a region of 10. mu. m.times.10 μm using an Atomic Force Microscope (AFM).

[ glass composition ]

Next, one embodiment of the composition range of each component that the optical glass of the present invention can contain will be described in detail. In the present specification, the content ratio of each component is expressed as mol% based on oxides unless otherwise specified. In the optical glass of the present invention, "substantially not containing" means not containing except inevitable impurities. The content of inevitable impurities is 0.1% or less in the present invention.

The optical glass of the present embodiment contains 30 to 80% of a component selected from TiO as a high refractive index component, for example, in mol% based on oxides, as a composition satisfying the above characteristics₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu), and SiO as a glass skeleton component in a total amount of 20-70%₂And B₂O₃When the alkaline earth metal component (MgO, CaO, SrO, BaO) is contained, the content ratio of BaO in the alkali metal component is 0.5 or less.

The components in the glass composition a satisfying the above conditions will be specifically described below. The optical glass of the present invention is not limited to the composition of the following embodiment as long as it has the above-described characteristics.

< glass composition A >

SiO₂The glass forming component is a component that imparts high strength and crack resistance to glass and improves the stability and chemical durability of glass. SiO 2₂The content ratio of (b) is preferably 5% to 44%. By SiO₂The content of (A) is 5% or more, and the viscosity of the glass can be 10¹Temperature T at dPa · s₁Is a preferred range. SiO 2₂The content ratio of (b) is preferably 7% or more, more preferably 9% or more, further preferably 10% or more, and particularly preferably 11% or more. On the other hand, by SiO₂The content ratio of (b) is 44% or less, and a component for obtaining a high refractive index can be contained in a larger amount. SiO 2₂The content ratio of (b) is more preferably 38% or less, more preferably 30% or less, still more preferably 20% or less, still more preferably 15% or less, and particularly preferably 12% or less.

B₂O₃The glass has improved mechanical properties such as strength and crack resistance and a reduced devitrification temperature in order to lower Tg, but if B is used₂O₃When the amount of (B) is large, the refractive index tends to be low. Thus, B₂O₃The content ratio of (b) is preferably 0% to 40%. B is₂O₃The content ratio of (b) is more preferably 35% or less, still more preferably 30% or less, still more preferably 25% or less, still more preferably 23% or less, and particularly preferably 22% or less. In addition, B₂O₃The content ratio of (b) is more preferably 5% or more, still more preferably 12% or more, still more preferably 18% or more, and particularly preferably 20% or more.

SiO₂And B₂O₃The glass-forming component is a component for improving the stability of glass. If SiO₂And B₂O₃When the total amount of (A) is large, the devitrification temperature of the glass is lowered, and the production becomes easy. Thus, SiO₂And B₂O₃The total amount of (A) is 20% or more. Preferably 25% or more, more preferably 28% or more, further preferably 30% or more, and particularly preferably 32% or more. On the other hand, if SiO is reduced₂And B₂O₃The total amount of (3) can increase the refractive index. Therefore, particularly when a high refractive index is required, it is preferably 70% or less, more preferably 50% or less, further preferably 40% or less, further preferably 35% or less, further preferably 33% or less, and particularly preferably 32% or less.

In the presence of B₂O₃In the case of (1), if SiO₂Relative to B₂O₃Specific ratio of SiO₂/B₂O₃Large, the glass is easily devitrified. Thus, in the presence of B₂O₃In the case of (2), SiO₂/B₂O₃Preferably 5.0 or less, more preferably 4.0 or less, further preferably 3.0 or less, further preferably 2.0 or less, further preferably 1.0 or less, further preferably 0.8 or less, and particularly preferably 0.6 or less.

TiO₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃(Ln is at least 1 selected from the group consisting of Y, La, Gd, Yb and Lu) is a high refractive index component for increasing the refractive index of the glass. The content ratio of these components is preferably 30% to 80% in total. In particular, when a high refractive index is required, it is preferably 40% or more, more preferably 55% or more, further preferably 60% or more, further preferably 65% or more, and particularly preferably 67% or more. On the other hand, if the high refractive index component exceeds 80%, devitrification is liable to occur. For applications requiring a lower surface roughness Ra, the content ratio of these components is more preferably 70% or less, still more preferably 60% or less, still more preferably 50% or less, and particularly preferably 45% or less.

Alkali metal component (Li)₂O+Na₂O+K₂O) is 0% to 10% in total. By increasing the alkali metal component, the Tg can be reduced. However, it is possible to use a single-layer,if Li is present₂O+Na₂O+K₂When O is too much, T is₁The viscosity curve tends to become steep, and the production characteristics tend to be lowered. On the other hand, if Li₂O+Na₂O+K₂If O is too small, T₁Easily increased melting temperature, and TiO in the high refractive index component₂、Nb₂O₅And the like are easily reduced and may be colored. Thus, in the presence of Li₂O+Na₂O+K₂In the case of O, it is preferably 0.5% to 10%. Li₂O+Na₂O+K₂O is more preferably 1% or more, further preferably 2% or more, further preferably 4% or more, and particularly preferably 5% or more. In addition, Li₂O+Na₂O+K₂O is preferably 6% or less, more preferably 3% or less, further preferably 2% or less, and particularly preferably 1% or less. "Li₂O+Na₂O+K₂O' represents Li₂O、Na₂O and K₂The total amount of at least 1 alkali metal oxide component in O. Hereinafter, the structure connected with "+" similarly means the total amount of at least 1 component selected from the components connected with "+".

Li₂The content ratio of O is 0% to 10%. Containing Li₂The content ratio of O is 0.2% to 10%. If containing Li₂O, the strength (Kc) and crack resistance (CIL) can be improved. The optical glass of the present invention contains Li₂In the case of O, the content ratio thereof is preferably 1% or more, more preferably 2% or more, further preferably 4% or more, and particularly preferably 5% or more. On the other hand, if Li₂When O is too large, devitrification is liable to occur. Particularly in the case where quality against devitrification is required, Li₂The content ratio of O is preferably 8% or less, more preferably 6% or less, further preferably 4% or less, further preferably 2% or less, and particularly preferably 1% or less.

In the case of chemically strengthening the optical glass of the present embodiment, Li₂The content of O is preferably 3.0% or more, more preferably 6.0% or more, further preferably 9.0% or more, particularly preferablyMore than 11.0% is selected.

Na₂O is a component for suppressing devitrification and lowering Tg, and the content ratio thereof is 0% to 10%. If containing Na₂O, an excellent devitrification-inhibiting effect can be obtained. The optical glass of the present invention contains Na₂In the case of O, the content ratio thereof is preferably 1% or more, more preferably 2% or more, further preferably 3% or more, and particularly preferably 4% or more. On the other hand, if Na₂When O is too large, the strength and crack resistance tend to be lowered. Especially in the case of required strength, Na₂The content ratio of O is preferably 7% or less, more preferably 4% or less, further preferably 2% or less, and particularly preferably 1% or less.

If Li is present₂O and Na₂When the total amount of O is increased, Tg tends to be lowered, and Li₂O and Na₂The total amount of O is preferably 0% to 10%. More preferably 6% or less, still more preferably 4% or less, still more preferably 2% or less, and particularly preferably 1% or less.

K₂O is a component for suppressing devitrification and lowering Tg, and the content ratio thereof is 0% to 10%. If containing K₂O, an excellent devitrification-inhibiting effect can be obtained. The optical glass of the present invention contains K₂In the case of O, the content ratio thereof is preferably 1% or more, more preferably 2% or more, further preferably 3% or more, and particularly preferably 4% or more. On the other hand, if K₂When O is too large, the strength and crack resistance tend to be lowered. Especially in the case of required strength, K₂The content ratio of O is preferably 7% or less, more preferably 4% or less, further preferably 2% or less, and particularly preferably 1% or less.

MgO is a component for improving the meltability of glass, suppressing devitrification, and adjusting optical constants such as the abbe number and refractive index of glass. On the other hand, if the amount of MgO is increased, devitrification is promoted instead. Therefore, the content ratio of MgO is preferably 0% or more and 10% or less. The content ratio of MgO is more preferably 8% or less, and particularly preferably 6% or less. The content ratio of MgO is preferably 0.3% or more, more preferably 0.5% or more, and still more preferably 1% or more.

CaO is a component that suppresses devitrification, but if the amount of CaO is large, the crack resistance is liable to decrease. Therefore, the content ratio of CaO is preferably 0% or more and 25% or less. The content ratio of CaO is more preferably 20% or less, still more preferably 10% or less, and particularly preferably 6% or less. The content ratio of CaO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

SrO is a component for improving the meltability of glass, suppressing devitrification, and adjusting the optical constants of glass. On the other hand, if the amount of SrO increases, devitrification is promoted instead. Therefore, the content ratio of SrO is preferably 0% or more and 20% or less. The content ratio of SrO is more preferably 15% or less, still more preferably 8% or less, and particularly preferably 4% or less. The content ratio of SrO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

If the total amount of MgO, CaO and SrO is increased, the glass is easily devitrified. Therefore, the total amount of MgO, CaO and SrO is preferably 30% or less. More preferably 20% or less, further preferably 12% or less, further preferably 10% or less, further preferably 5% or less, and particularly preferably 2% or less.

BaO is a component for suppressing devitrification, but if the amount of BaO is large, the density tends to be large. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The content ratio of BaO is more preferably 25% or less, further preferably 15% or less, further preferably 8% or less, and particularly preferably 4% or less. The content ratio of BaO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

When the alkaline earth metal component (MgO + CaO + SrO + BaO) is contained, the specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal component (BaO/(MgO + CaO + SrO + BaO)) to 0.5 or less. Preferably 0.4 or less, more preferably 0.3 or less, further preferably 0.2 or less, and particularly preferably 0.1 or less. By increasing the content ratio of BaO in the alkali metal component, the devitrification temperature can be reduced. For applications requiring a lower surface roughness Ra, the surface roughness is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and particularly preferably 0.4 or more.

If the alkali metal component (Li)₂O+Na₂O+K₂O) and the total amount of the alkaline earth metal components (MgO + CaO + SrO + BaO) increase, the Tg of the glass tends to decrease. Therefore, the total amount of the alkali metal component and the alkaline earth metal component is preferably 30% or less. More preferably 16% or less, still more preferably 12% or less, still more preferably 10% or less, still more preferably 5% or less, and particularly preferably 2% or less.

Al₂O₃A component for improving chemical durability, but if Al₂O₃When the amount of the glass increases, the glass is easily devitrified. Thus, Al₂O₃The content ratio of (b) is preferably 0% to 5%. Al (Al)₂O₃The content ratio of (b) is more preferably 3% or less, and particularly preferably 2% or less. In addition, Al₂O₃The content ratio of (b) is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

TiO₂The content ratio of the component for increasing the dispersion of the glass to increase the refractive index of the glass is 0% to 50%. In the presence of TiO₂In the case of (3), the content ratio thereof is preferably 10% or more, more preferably 20% or more, further preferably 25% or more, further preferably 28% or more, further preferably 30% or more, and particularly preferably 32% or more. On the other hand, if TiO₂When the amount is too large, coloring tends to occur, and the transmittance decreases. Therefore, TiO particularly when transmittance is required₂The content ratio of (b) is preferably 50% or less, more preferably 40% or less, further preferably 37% or less, further preferably 35% or less, further preferably 34% or less, further preferably 33% or less, and particularly preferably 32% or less.

In the presence of B₂O₃In the case of (1), if TiO₂Relative to B₂O₃Specific ratio of TiO₂/B₂O₃Large, the melting temperature needs to be raised, soTi is easily reduced, glass is easily colored, and transmittance is easily lowered. Thus, in the presence of B₂O₃In the case of (2), TiO₂/B₂O₃Preferably 5.0 or less, more preferably 4.0 or less, further preferably 3.0 or less, further preferably 2.0 or less, further preferably 1.8 or less, further preferably 1.7 or less, further preferably 1.6 or less, and particularly preferably 1.5 or less.

By adding WO₃The devitrification of the glass is suppressed, but if the amount added is too large, the glass is liable to devitrify on the contrary. Thus, WO₃The content ratio of (b) is preferably 0% to 10%. WO₃The content ratio of (b) is more preferably 6% or less, still more preferably 2% or less, still more preferably 1.5% or less, still more preferably 1.0% or less, and particularly preferably 0.5% or less. In addition, by adding WO₃The refractive index of the glass can be increased. Therefore, WO is particularly suitable for cases where a high refractive index is required₃The content ratio of (b) is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

Nb₂O₅To improve the refractive index of glass and to reduce the Abbe number (v)_d) The composition of (1). Nb₂O₅The content ratio of (b) is 0% to 35%. Nb₂O₅The content ratio of (b) is more preferably 1% or more, further preferably 2% or more, further preferably 2.5% or more, further preferably 3% or more, further preferably 4% or more, further preferably 5% or more, and particularly preferably 6% or more.

In addition, if Nb₂O₅Too much, it is easily devitrified. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 20% or less, more preferably 15% or less, further preferably 10% or less, further preferably 6% or less, further preferably 4% or less, further preferably 3% or less, further preferably 2% or less, and particularly preferably 1% or less.

If TiO is present₂、WO₃And Nb₂O₅When the total amount of (A) is small, the refractive index of the glass is lowered.Thus, TiO₂、WO₃And Nb₂O₅The total amount of (a) is preferably 10% to 50%. More preferably 15% or more, still more preferably 20% or more, still more preferably 25% or more, and particularly preferably 30% or more.

Y₂O₃To increase the refractive index of the glass and to be able to adjust the T of the glass₁The content ratio of the component adjusted to a preferable range is 0% or more and 7% or less. Y is₂O₃The content ratio of (b) is preferably 1% or more, more preferably 2% or more, further preferably 2.5% or more, further preferably 3% or more, further preferably 3.5% or more, further preferably 4% or more, and particularly preferably 5% or more. In addition, if Y is₂O₃Too much, it is easily devitrified. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 5% or less, more preferably 4% or less, still more preferably 3.5% or less, and particularly preferably 3% or less.

ZrO₂The content ratio of the component for increasing the chemical durability of the glass to increase the refractive index of the glass is 0% to 20%. By containing ZrO₂The crack resistance can be improved. In the presence of ZrO₂In the case of (3), the content ratio thereof is preferably 1% or more, more preferably 3% or more, further preferably 5% or more, further preferably 6% or more, and particularly preferably 6.5% or more. On the other hand, if ZrO₂Too much, it is easily devitrified. Thus, for applications requiring a lower surface roughness Ra, ZrO₂The content ratio of (b) is more preferably 15% or less, still more preferably 10% or less, still more preferably 8% or less, and particularly preferably 7% or less.

ZnO is a component for improving mechanical properties such as strength and crack resistance of the glass, and the content thereof is 0% to 15%. When ZnO is contained, the content ratio is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the amount of ZnO is large, devitrification is easy, and therefore, for applications requiring a lower surface roughness Ra, the content ratio of ZnO is more preferably 10% or less, still more preferably 5% or less, still more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

La₂O₃The content ratio of the component for increasing the refractive index of the glass is 0% to 35%. In the presence of La₂O₃In the case of (3), the content ratio thereof is preferably 10% or more, more preferably 15% or more, further preferably 16% or more, further preferably 18% or more, and particularly preferably 20% or more. On the other hand, if La₂O₃When the amount of (B) is too large, mechanical properties are deteriorated and devitrification temperature is increased. Therefore, La is a material that is important for mechanical properties and manufacturing properties₂O₃The content ratio of (b) is preferably 30% or less. More preferably 25% or less, still more preferably 22% or less, still more preferably 20% or less, still more preferably 19% or less, still more preferably 18% or less, and particularly preferably 17% or less.

Gd₂O₃The content ratio of the component for increasing the refractive index of the glass is 0% to 15%. In the presence of Gd₂O₃In the case of (3), the content ratio thereof is preferably 1% or more, more preferably 2% or more, further preferably 3% or more, further preferably 4% or more, and particularly preferably 5% or more. On the other hand, if Gd₂O₃When the amount of (B) is too large, mechanical properties are deteriorated and devitrification temperature is increased. Therefore, when mechanical properties and manufacturing properties are important, Gd is used₂O₃The content ratio of (b) is preferably 10% or less, more preferably 7% or less, further preferably 5% or less, further preferably 4% or less, further preferably 3% or less, further preferably 2% or less, and particularly preferably 1% or less.

If ZrO of₂、Ta₂O₅And Nb₂O₅In total amount of (A) to SiO₂And B₂O₃Ratio of the total amount of (ZrO)₂+Ta₂O₅+Nb₂O₅)/(SiO₂+B₂O₃) When the viscosity of the glass is increased, the devitrification viscosity of the glass is liable to decrease. Therefore, aZrO₂+Ta₂O₅+Nb₂O₅)/(SiO₂+B₂O₃) Preferably 1.0 or less, more preferably 0.8 or less, further preferably 0.6 or less, further preferably 0.4 or less, and particularly preferably 0.35 or less.

If Nb₂O₅、TiO₂、WO₃And Ta₂O₅The total amount of (A) to La₂O₃、Gd₂O₃、Y₂O₃And Yb₂O₃Ratio of the total amount of (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the transmittance is increased, the glass is easily colored and the transmittance is easily lowered. Thus, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 10.0 or less, more preferably 8.0 or less, further preferably 6.0 or less, further preferably 5.0 or less, further preferably 4.5 or less, further preferably 4.0 or less, further preferably 3.0 or less, further preferably 2.5 or less, further preferably 2.0 or less, further preferably 1.5 or less, and particularly preferably 1.3 or less. On the other hand, if (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the Tg of the glass is small, the Tg is liable to decrease. Therefore, for applications requiring high heat resistance, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 0.5 or more, more preferably 0.7 or more, further preferably 0.9 or more, further preferably 1.1 or more, further preferably 1.2 or more, further preferably 1.3 or more, further preferably 1.4 or more, further preferably 2.0 or moreMore preferably 3.0 or more, and particularly preferably 3.5 or more.

As₂O₃Are harmful chemical substances, and therefore, in recent years, there is a tendency to curtail use, and measures are required in terms of environmental countermeasures. Therefore, when importance is attached to the environmental influence, it is preferable that the additive does not substantially contain the additive except for inevitable mixing.

In addition, the optical glass of the present embodiment preferably contains Sb₂O₃And SnO₂At least one of (1). These are not essential components, but may be added for the purpose of adjusting refractive index characteristics, improving meltability, suppressing coloring, improving transmittance, clarifying, improving chemical durability, and the like. When these components are contained, the total content is preferably 10% or less, more preferably 5% or less, further preferably 3% or less, and particularly preferably 1% or less.

Further, the optical glass of the present embodiment preferably contains V₂O₅。V₂O₅It is not essential, but may be added for the purpose of improving transmittance, improving clarity, and the like. In the presence of V₂O₅In the case of (3), the content is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

In addition, the optical glass of the present embodiment preferably contains F. F is not necessarily required, but may be added for the purpose of improving meltability, transmittance, clarity, and the like. When F is contained, it is preferably 5% or less, more preferably 3% or less.

In the optical glass of the present embodiment, it is preferable that an operation of increasing the amount of water in the molten glass is performed in a melting step of obtaining the molten glass by heating and melting the glass raw material in the melting vessel. The operation of increasing the amount of water in the glass is not limited, and for example, a treatment of adding water vapor to a melting atmosphere and a treatment of blowing a gas containing water vapor into a melt may be considered. The operation of increasing the amount of water is not essential, but may be performed for the purpose of improving transmittance, improving clarity, and the like.

In addition, in this embodimentThe optical glass of the embodiment contains Li₂O、Na₂In the case of an alkali metal oxide such as O, chemical strengthening can be achieved by replacing Li ions with Na ions or K ions and replacing Na ions with K ions. That is, if the chemical strengthening treatment is performed, the strength of the optical glass can be improved.

< glass composition A1 >

The glass composition a1 is a glass composition in which the content of the alkaline earth metal component in the glass composition a is 5% or less, and each component will be described. The components not described in the glass composition a1 are the same as those described in the above description of the components of the glass composition a, and therefore, are omitted.

SiO₂The glass forming component is a component that imparts high strength and crack resistance to glass and improves the stability and chemical durability of glass. SiO 2₂The content ratio of (b) is preferably 5% to 30%. By SiO₂The content of (A) is 5% or more, and the viscosity of the glass can be 10¹Temperature T at dPa · s₁Is a preferred range. SiO 2₂The content ratio of (b) is preferably 7% or more, more preferably 9% or more, further preferably 10% or more, and particularly preferably 11% or more. On the other hand, by SiO₂The content ratio of (b) is 30% or less, and a component for obtaining a high refractive index can be contained in a larger amount. SiO 2₂The content ratio of (b) is more preferably 25% or less, more preferably 20% or less, still more preferably 15% or less, still more preferably 13% or less, and particularly preferably 12% or less.

B₂O₃The glass has improved mechanical properties such as strength and crack resistance and a reduced devitrification temperature in order to lower Tg, but if B is used₂O₃When the amount of (B) is large, the refractive index tends to be low. Thus, B₂O₃The content ratio of (b) is preferably 5% to 40%. B is₂O₃The content ratio of (b) is more preferably 35% or less, still more preferably 30% or less, still more preferably 25% or less, still more preferably 23% or more, and particularly preferably 22% or less. In addition, B₂O₃The content ratio of (A) is more preferably 10% or more, and still more preferably 15% or moreMore preferably 18% or more, and particularly preferably 20% or more.

SiO₂And B₂O₃The glass forming component is a component for improving the stability of the glass, and is 20% to 45% in total. If SiO₂And B₂O₃When the total amount of (A) is large, the devitrification temperature of the glass is lowered, and the production becomes easy. Thus, SiO₂And B₂O₃The total amount of (A) is 20% or more. Preferably 25% or more, more preferably 28% or more, further preferably 30% or more, and particularly preferably 32% or more. On the other hand, if SiO is reduced₂And B₂O₃The total amount of (3) can increase the refractive index. Therefore, particularly when a high refractive index is required, it is preferably 45% or less, more preferably 40% or less, further preferably 35% or less, further preferably 33% or less, and particularly preferably 32% or less.

If SiO₂Relative to B₂O₃Specific ratio of SiO₂/B₂O₃Large, the glass is easily devitrified. Thus, SiO₂/B₂O₃Preferably 1.4 or less, more preferably 1.2 or less, further preferably 1.0 or less, further preferably 0.8 or less, and particularly preferably 0.6 or less.

TiO₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃(Ln is at least 1 selected from the group consisting of Y, La, Gd, Yb and Lu) is a high refractive index component for increasing the refractive index of the glass. The content ratio of these components is preferably 45% to 80% in total. In particular, when a high refractive index is required, it is preferably 50% or more, more preferably 55% or more, further preferably 60% or more, further preferably 65% or more, and particularly preferably 67% or more. On the other hand, if the high refractive index component exceeds 80%, devitrification is liable to occur. For applications requiring a lower surface roughness Ra, the content ratio of these components is more preferably 75% or less, still more preferably 70% or less, and particularly preferably 68% or less.

MgO is a component for improving the meltability of glass, suppressing devitrification, and adjusting optical constants such as the abbe number and refractive index of glass. On the other hand, if the amount of MgO is increased, devitrification is promoted instead. Therefore, the content ratio of MgO is preferably 0% or more and 5% or less. The content ratio of MgO is more preferably 4% or less, and particularly preferably 2% or less. The content ratio of MgO is preferably 0.3% or more, more preferably 0.5% or more, and still more preferably 1% or more.

CaO is a component that suppresses devitrification, but if the amount of CaO is large, the crack resistance is liable to decrease. Therefore, the content ratio of CaO is preferably 0% or more and 5% or less. The content ratio of CaO is more preferably 4% or less, still more preferably 2% or less, and particularly preferably 1% or less. The content ratio of CaO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

SrO is a component for improving the meltability of glass, suppressing devitrification, and adjusting the optical constants of glass. On the other hand, if the amount of SrO increases, devitrification is promoted instead. Therefore, the SrO content is preferably 0% or more and 5% or less. The content ratio of SrO is more preferably 15% or less, still more preferably 4% or less, and particularly preferably 2% or less. The content ratio of SrO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

If the total amount of MgO, CaO and SrO is increased, the glass is easily devitrified. Therefore, the total amount of MgO, CaO and SrO is preferably 5% or less. More preferably 4% or less, still more preferably 3% or less, still more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

BaO is a component for suppressing devitrification, but if the amount of BaO is large, the density tends to be large. Therefore, when BaO is contained, it is preferably 0% or more and 5% or less. The content ratio of BaO is more preferably 4% or less, further preferably 3% or less, further preferably 2% or less, and particularly preferably 1% or less. The content ratio of BaO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

When the alkaline earth metal component (MgO + CaO + SrO + BaO) is contained, the specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal component (BaO/(MgO + CaO + SrO + BaO)) to 0.5 or less. Preferably 0.4 or less, more preferably 0.3 or less, further preferably 0.2 or less, and particularly preferably 0.1 or less. By increasing the content ratio of BaO in the alkali metal component, the devitrification temperature can be reduced. For applications requiring a lower surface roughness Ra, the surface roughness is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and particularly preferably 0.4 or more.

If the alkali metal component (Li)₂O+Na₂O+K₂O) and the total amount of the alkaline earth metal components (MgO + CaO + SrO + BaO) increase, the Tg of the glass tends to decrease. Therefore, the total amount of the alkali metal component and the alkaline earth metal component is preferably 15% or less. More preferably 12% or less, still more preferably 10% or less, still more preferably 5% or less, still more preferably 3% or less, and particularly preferably 2% or less.

If TiO is present₂Relative to B₂O₃Specific ratio of TiO₂/B₂O₃If the glass is large, the melting temperature needs to be increased, so that Ti is easily reduced, the glass is easily colored, and the transmittance is easily lowered. Thus, TiO₂/B₂O₃Preferably 2.0 or less, more preferably 1.8 or less, further preferably 1.7 or less, further preferably 1.6 or less, and particularly preferably 1.5 or less.

The optical glass obtained from glass composition A1 has a high refractive index (n) in the range of 1.92-2.15_d). Refractive index (n)_d) Is 1.92 or more. The optical glass is suitable as an optical glass for use in wearable devices in view of widening the angle of an image, increasing brightness and contrast, improving light guiding characteristics, improving ease of processing a diffraction grating, and the like. Further, a small-sized imaging glass lens having a wide imaging angle, which is used for applications such as an in-vehicle camera and a robot vision sensor, is preferable because it is smaller and has a wider imaging range. The refractive index (n)_d) Preferably 1.95 or more, more preferably 1.97 or more, further preferably 1.98 or more, further preferably 1.99 or more, further preferably 2.00 or more.

On the other hand, refractive index (n)_d) A glass exceeding 2.15 tends to have a high density and a high devitrification temperature. In particular, when the density of the optical glass is regarded as high or low, the refractive index (n) is set_d) Preferably 2.10 or less, more preferably 2.06 or less, further preferably 2.03 or less, further preferably 2.01 or less, further preferably 1.98 or less, further preferably 1.95 or less, further preferably 1.94 or less, further preferably 1.93 or less.

In addition, the optical glass obtained from glass composition A1 had a glass density of 4.0g/cm³Above and 6.0g/cm³The following density (d). By having the density in the above range, the optical glass can provide a satisfactory wearing feeling for a user when used in wearable equipment, and can reduce the weight of the entire device when used in an in-vehicle camera, a robot vision sensor, or the like. The density (d) is preferably 5.8g/cm³Hereinafter, more preferably 5.6g/cm³Hereinafter, more preferably 5.4g/cm³Hereinafter, more preferably 5.2g/cm³Hereinafter, more preferably 5.1g/cm³Hereinafter, more preferably 5.0g/cm³The following.

On the other hand, in order to make the surface of the optical glass less likely to be scratched, the density (d) is preferably 4.0g/cm³Above, more preferably 4.3g/cm³Above, more preferably 4.6g/cm³Above, more preferably 4.7g/cm³Above, particularly preferably 4.8g/cm³The above.

< glass composition A2 >

The content of alkaline earth metal in the glass composition A is more than 5% and 50% or less, and B₂O₃The glass composition with less than 15% is defined as glass composition A2, and the respective components will be described. The components not described in the glass composition a2 are the same as those described in the above description of the components of the glass composition a, and therefore, are omitted.

SiO₂The glass forming component imparts high strength and crack resistance to the glass, and improves the stability and chemical durability of the glassThe composition of (1). SiO 2₂The content ratio of (b) is preferably 5% to 44%. By SiO₂The content of (A) is 5% or more, and the viscosity of the glass can be 10¹Temperature T at dPa · s₁Is a preferred range. SiO 2₂The content ratio of (b) is preferably 10% or more, more preferably 15% or more, further preferably 20% or more, further preferably 24% or more, further preferably 28% or more, and particularly preferably 30% or more. On the other hand, by SiO₂The content ratio of (b) is 44% or less, and a component for obtaining a high refractive index may be contained. SiO 2₂The content ratio of (b) is more preferably 37% or less, still more preferably 35.5% or less, still more preferably 34% or less, still more preferably 33% or less, and particularly preferably 31% or less.

B₂O₃The glass-forming component is an arbitrary component. B is₂O₃To lower Tg, the mechanical properties such as strength and crack resistance of the glass are improved, and the devitrification temperature is lowered. Based on the balance of refractive index and mechanical strength, B₂O₃The content ratio of (b) is preferably 0% or more and less than 15%. B is₂O₃The content ratio of (b) is more preferably 14% or less, still more preferably 13% or less, still more preferably 12% or less, still more preferably 11% or more, and particularly preferably 10% or less. In addition, B₂O₃The content ratio of (b) is more preferably 1% or more, still more preferably 3% or more, still more preferably 5% or more, and particularly preferably 7% or more.

SiO₂And B₂O₃The glass forming component is a component for improving the stability of the glass, and is 30% to 70% in total. If SiO₂And B₂O₃When the total amount of (A) is large, the devitrification temperature of the glass is lowered, and the production becomes easy. Thus, SiO₂And B₂O₃The total amount of (A) is more than 30%. Preferably 32% or more, more preferably 34% or more, further preferably 36% or more, and particularly preferably 37% or more. On the other hand, if SiO is reduced₂And B₂O₃The total amount of (3) can increase the refractive index.Therefore, particularly when a high refractive index is required, it is preferably 70% or less, more preferably 60% or less, further preferably 50% or less, further preferably 40% or less, and particularly preferably 35% or less.

In the presence of B₂O₃In the case of (1), if SiO₂Relative to B₂O₃Specific ratio of SiO₂/B₂O₃Large, the glass is easily devitrified. Thus, in the presence of B₂O₃In the case of (2), SiO₂/B₂O₃Preferably 5.0 or less, more preferably 4.5 or less, further preferably 4.0 or less, further preferably 3.5 or less, and particularly preferably 3.0 or less.

TiO₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃(Ln is at least 1 selected from the group consisting of Y, La, Gd, Yb and Lu) is a high refractive index component for increasing the refractive index of the glass. The content ratio of these components is preferably 30% to 55% in total. In particular, when a high refractive index is required, it is preferably 33% or more, more preferably 35% or more, still more preferably 36% or more, still more preferably 37% or more, and particularly preferably 38% or more. On the other hand, if the high refractive index component is increased, devitrification is liable to occur. For applications requiring a lower surface roughness Ra, the content ratio of these components is more preferably 50% or less, still more preferably 45% or less, still more preferably 40% or less, and particularly preferably 35% or less.

Alkali metal component (Li)₂O+Na₂O+K₂O) is 0% to 10% in total. By increasing the alkali metal component, the Tg can be reduced. However, if Li₂O+Na₂O+K₂When O is too much, T is₁The viscosity curve tends to become steep, and the production characteristics tend to be lowered. On the other hand, if Li₂O+Na₂O+K₂If O is too small, T₁The melting temperature tends to be high, and coloring may occur. Thus, in the presence of Li₂O+Na₂O+K₂In the case of O, it is preferably 0.5% or moreAnd less than 10%. Li₂O+Na₂O+K₂O is more preferably 1% or more, further preferably 1.5% or more, further preferably 2% or more, and particularly preferably 3% or more. In addition, Li₂O+Na₂O+K₂O is preferably 6% or less, more preferably 4% or less, further preferably 3% or less, and particularly preferably 2% or less.

Li₂The content ratio of O is 0% to 10%. Containing Li₂The content ratio of O is 0.2% to 10%. If containing Li₂O, the strength (Kc) and crack resistance (CIL) can be improved. The optical glass of the present invention contains Li₂In the case of O, the content ratio thereof is preferably 0.5% or more, more preferably 1% or more, further preferably 1.5% or more, and particularly preferably 2% or more. On the other hand, if Li₂When O is too large, devitrification is liable to occur. Particularly in the case where devitrification is a problem, Li₂The content ratio of O is preferably 8% or less, more preferably 6% or less, further preferably 4% or less, and particularly preferably 2% or less.

In the case of chemically strengthening the optical glass of the present embodiment, Li₂The content ratio of O is preferably 3.0% or more, more preferably 6.0% or more, further preferably 9.0% or more, and particularly preferably 11.0% or more.

CaO is a component that suppresses devitrification, but if the amount of CaO is large, the crack resistance is liable to decrease. Therefore, the content ratio of CaO is preferably 0% or more and 25% or less. The content ratio of CaO is more preferably 20% or less, further preferably 15% or less, further preferably 10% or less, further preferably 8% or less, further preferably 7% or less, and particularly preferably 6.5% or less. The content ratio of CaO is more preferably 2% or more, further preferably 4% or more, further preferably 5% or more, and particularly preferably 6% or more.

SrO is a component for improving the meltability of glass, suppressing devitrification, and adjusting the optical constants of glass. On the other hand, if the amount of SrO increases, devitrification is promoted instead. Therefore, the content ratio of SrO is preferably 0% or more and 20% or less. The content ratio of SrO is more preferably 15% or less, still more preferably 10% or less, still more preferably 9% or less, still more preferably 8% or less, and particularly preferably 7% or less. The SrO content is more preferably 2% or more, still more preferably 4% or more, and particularly preferably 6% or more.

If the total amount of MgO, CaO and SrO is increased, the glass is easily devitrified. Therefore, the total amount of MgO, CaO and SrO is preferably 30% or less. More preferably 25% or less, still more preferably 18% or less, still more preferably 16% or less, still more preferably 15% or less, and particularly preferably 14% or less.

BaO is a component for suppressing devitrification, but if the amount of BaO is large, the density tends to be large. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The content ratio of BaO is more preferably 20% or less, further preferably 15% or less, further preferably 11% or less, further preferably 9% or less, and particularly preferably 8% or less. The content ratio of BaO is more preferably 2% or more, still more preferably 4% or more, and particularly preferably 6% or more.

The content ratio of the alkaline earth metal components (MgO + CaO + SrO + BaO) is 5% to 50% in total. If the total amount is 50% or less, devitrification of the glass can be suppressed, and therefore, it is preferable. More preferably 40% or less, further preferably 30% or less, further preferably 27% or less, further preferably 25% or less, further preferably 23% or less, further preferably 21% or less, and particularly preferably 20% or less. It is preferable that the total amount is 5% or more because the meltability of the glass can be improved. More preferably 10% or more, further preferably 13% or more, further preferably 16% or more, further preferably 18% or more, and particularly preferably 19% or more.

The specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal component (MgO + CaO + SrO + BaO) (BaO/(MgO + CaO + SrO + BaO)) to 0.5 or less. Preferably 0.45 or less, more preferably 0.42 or less, further preferably 0.40 or less, and particularly preferably 0.35 or less. By increasing the content of BaO in the alkaline earth metal component, the devitrification temperature can be lowered and the production characteristics can be improved. When the production characteristics are particularly important, the production characteristics are preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and particularly preferably 0.35 or more.

If the alkali metal component (Li)₂O+Na₂O+K₂O) and the total amount of the alkaline earth metal components (MgO + CaO + SrO + BaO) increase, the Tg of the glass tends to decrease. Therefore, the total amount of the alkali metal component and the alkaline earth metal component is preferably 30% or less. More preferably 16% or less, still more preferably 14% or less, still more preferably 13% or less, still more preferably 12% or less, and particularly preferably 11.5% or less.

TiO₂The content ratio of the component for increasing the dispersion of the glass to increase the refractive index of the glass is 0% to 50%. In the presence of TiO₂In the case of (3), the content ratio thereof is preferably 10% or more, more preferably 15% or more, further preferably 17% or more, further preferably 19% or more, further preferably 20% or more, and particularly preferably 22% or more. On the other hand, if TiO₂When the amount is too large, coloring tends to occur, and the transmittance decreases. Therefore, TiO particularly when transmittance is required₂The content ratio of (b) is preferably 50% or less, more preferably 40% or less, further preferably 30% or less, further preferably 25% or less, further preferably 23% or less, further preferably 22% or less, and particularly preferably 21% or less.

In the presence of B₂O₃In the case of (1), if TiO₂Relative to B₂O₃Specific ratio of TiO₂/B₂O₃If the glass is large, the melting temperature needs to be increased, so that Ti is easily reduced, the glass is easily colored, and the transmittance is easily lowered. Thus, in the presence of B₂O₃In the case of (2), TiO₂/B₂O₃Preferably 5.0 or less, more preferably 4.5 or less, further preferably 4.0 or less, further preferably 3.5 or less, further preferably 3.0 or less, further preferably 2.8 or less, and particularly preferably 2.7 or less.

Nb₂O₅In order to increase the refractive index of the glass,and reducing the Abbe number (v)_d) The composition of (1). Nb₂O₅The content ratio of (b) is 0% to 35%. Nb₂O₅The content ratio of (b) is preferably 2% or more, more preferably 4% or more, further preferably 5% or more, further preferably 6% or more, further preferably 7% or more, further preferably 8% or more, and particularly preferably 10% or more.

In addition, if Nb₂O₅Too much, it is easily devitrified. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 20% or less, more preferably 10% or less, still more preferably 8% or less, and particularly preferably 7% or less.

If TiO is present₂、WO₃And Nb₂O₅When the total amount of (A) is small, the refractive index of the glass is lowered. Thus, TiO₂、WO₃And Nb₂O₅The total amount of (a) is preferably 10% to 50%. More preferably 14% or more, still more preferably 18% or more, still more preferably 22% or more, and particularly preferably 26% or more. On the other hand, if TiO₂、WO₃And Nb₂O₅If the total amount of (A) is large, devitrification is liable to occur. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, and particularly preferably 28% or less.

ZrO₂The content ratio of the component for increasing the chemical durability of the glass to increase the refractive index of the glass is 0% to 20%. By containing ZrO₂The crack resistance can be improved. In the presence of ZrO₂In the case of (3), the content ratio thereof is more preferably 1% or more, still more preferably 2% or more, still more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if ZrO₂Too much, it is easily devitrified. Therefore, particularly in the case where the production characteristics become important, ZrO₂The content ratio of (b) is more preferably 15% or less, still more preferably 10% or less, still more preferably 6% or less, and particularly preferably 5% or less.

ZnO is a component for improving mechanical properties such as strength and crack resistance of the glass, and the content thereof is 0% to 15%. When ZnO is contained, the content ratio is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the amount of ZnO is large, devitrification is easy, and therefore the content ratio of ZnO is more preferably 10% or less, still more preferably 5% or less, still more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

La₂O₃The content ratio of the component for increasing the refractive index of the glass is 0% to 35%. In the presence of La₂O₃In the case of (3), the content ratio thereof is preferably 2% or more, more preferably 4% or more, further preferably 5% or more, further preferably 6% or more, and particularly preferably 7% or more. On the other hand, if La₂O₃When the amount of (B) is too large, mechanical properties are deteriorated and devitrification temperature is increased. Therefore, La is a material that is important for mechanical properties and manufacturing properties₂O₃The content ratio of (b) is preferably 30% or less. More preferably 25% or less, further preferably 20% or less, further preferably 15% or less, further preferably 10% or less, further preferably 9% or less, and particularly preferably 8% or less.

If Nb₂O₅、TiO₂、WO₃And Ta₂O₅The total amount of (A) to La₂O₃、Gd₂O₃、Y₂O₃And Yb₂O₃Ratio of the total amount of (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the transmittance is increased, the glass is easily colored and the transmittance is easily lowered. Thus, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 10.0 or less, more preferably 8.0 or less, further preferably 6.0 or less, further preferably oneThe step is preferably 5.0 or less, more preferably 4.5 or less, and particularly preferably 4.0 or less. On the other hand, if (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the Tg of the glass is small, the Tg is liable to decrease. Therefore, for applications requiring high heat resistance, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 0.5 or more, more preferably 1.0 or more, further preferably 2.0 or more, further preferably 3.0 or more, and particularly preferably 3.5 or more.

The optical glass obtained from glass composition A2 has a high refractive index (n) in the range of 1.81-1.96_d). Refractive index (n)_d) Is 1.81 or more. The optical glass is suitable as an optical glass for use in wearable devices in view of widening the angle of an image, increasing brightness and contrast, improving light guiding characteristics, improving ease of processing a diffraction grating, and the like. Further, a small-sized imaging glass lens having a wide imaging angle, which is used for applications such as an in-vehicle camera and a robot vision sensor, is preferable because it is smaller and has a wider imaging range. The refractive index (n)_d) Preferably 1.84 or more, more preferably 1.86 or more, further preferably 1.87 or more, further preferably 1.88 or more, further preferably 1.89 or more, and particularly preferably 1.90 or more.

On the other hand, refractive index (n)_d) A glass exceeding 1.96 tends to have a high density and a high devitrification temperature. In particular, when the decrease in the density of the optical glass is emphasized, the refractive index (n) is set to be higher_d) Preferably 1.94 or less, more preferably 1.93 or less, further preferably 1.92 or less, further preferably 1.91 or less, further preferably 1.90 or less, further preferably 1.89 or less, further preferably 1.88 or less, further preferably 1.87 or less.

In addition, the optical glass obtained from glass composition A2 had a glass content of 3.3g/cm³Above and 5.4g/cm³The following density (d). By having the density in the above range, the optical glass can provide a satisfactory wearing feeling for a user when used in wearable equipment, and can reduce the weight of the entire device when used in an in-vehicle camera, a robot vision sensor, or the like. The density (d) is preferably 5.2g/cm³Hereinafter, more preferably 5.0g/cm³Hereinafter, more preferably 4.8g/cm³Hereinafter, more preferably 4.6g/cm³Hereinafter, more preferably 4.4g/cm³Hereinafter, more preferably 4.2g/cm³The following.

On the other hand, in order to make the surface of the optical glass less likely to be scratched, the density (d) is preferably 3.6g/cm³The above. More preferably 3.8g/cm³Above, more preferably 4.0g/cm³Above, more preferably 4.2g/cm³Above, particularly preferably 4.3g/cm³The above.

The optical glass has a devitrification temperature of 1300 ℃ or lower. With such characteristics, devitrification of the glass during molding can be suppressed, and the moldability is good. The devitrification temperature is more preferably 1275 ℃ or lower, still more preferably 1240 ℃ or lower, still more preferably 1225 ℃ or lower, still more preferably 1200 ℃ or lower, still more preferably 1175 ℃ or lower, still more preferably 1150 ℃ or lower, still more preferably 1125 ℃ or lower, still more preferably 1100 ℃ or lower, still more preferably 1075 ℃ or lower, and particularly preferably 1050 ℃ or lower. Here, the devitrification temperature is the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more are not visible on the surface and inside of the glass when the heated and melted glass is cooled by natural cooling.

< glass composition A3 >

The content of alkaline earth metal in the glass composition A is more than 5% and 50% or less, and B₂O₃The components will be described with the glass composition a3 being a glass composition of 15% or more. The components not described in the glass composition a3 are the same as those described in the above description of the components of the glass composition a, and therefore, are omitted.

SiO₂The glass forming component is a component that imparts high strength and crack resistance to glass and improves the stability and chemical durability of glass. SiO 2₂The content ratio of (b) is preferably 5% to 44%. By SiO₂The content of (A) is 5% or more, and the viscosity of the glass can be 10¹Temperature T at dPa · s₁Is a preferred range. SiO 2₂The content ratio of (b) is preferably 5% or more, more preferably 10% or more, further preferably 12% or more, further preferably 13% or more, further preferably 14% or more, and particularly preferably 15% or more. On the other hand, by SiO₂The content ratio of (b) is 44% or less, and a component for obtaining a high refractive index may be contained. SiO 2₂The content ratio of (b) is more preferably 37% or less, still more preferably 30% or less, still more preferably 23% or less, still more preferably 20% or less, and particularly preferably 17% or less.

B₂O₃Is an essential component for forming glass. B is₂O₃The glass has improved mechanical properties such as strength and crack resistance and a reduced devitrification temperature in order to lower Tg, but if B is used₂O₃When the amount of (B) is large, the refractive index tends to be low. Thus, B₂O₃The content ratio of (b) is preferably 15% to 40%. B is₂O₃The content ratio of (b) is more preferably 35% or less, still more preferably 32% or less, still more preferably 29% or less, still more preferably 27% or less, and particularly preferably 26% or less. In addition, B₂O₃The content ratio of (b) is more preferably 18% or more, still more preferably 21% or more, still more preferably 23% or more, and particularly preferably 24% or more.

SiO₂And B₂O₃The glass forming component is a component for improving the stability of the glass, and is 30% to 70% in total. If SiO₂And B₂O₃When the total amount of (A) is large, the devitrification temperature of the glass is lowered, and the production becomes easy. Thus, SiO₂And B₂O₃Is 30% or more, preferably 32% or more, more preferably34% or more, more preferably 36% or more, and particularly preferably 39% or more. On the other hand, if SiO is reduced₂And B₂O₃The total amount of (3) can increase the refractive index. Therefore, particularly when a high refractive index is required, it is preferably 70% or less, more preferably 60% or less, further preferably 50% or less, further preferably 45% or less, and particularly preferably 42% or less.

In the presence of B₂O₃In the case of (1), if SiO₂Relative to B₂O₃Specific ratio of SiO₂/B₂O₃Large, the glass is easily devitrified. Thus, in the presence of B₂O₃In the case of (2), SiO₂/B₂O₃Preferably 5.0 or less, more preferably 3.0 or less, further preferably 2.0 or less, further preferably 1.5 or less, and particularly preferably 1.0 or less.

TiO₂、Ta₂O₅、WO₃、Nb₂O₅、ZrO₂And Ln₂O₃(Ln is at least 1 selected from the group consisting of Y, La, Gd, Yb and Lu) is a high refractive index component for increasing the refractive index of the glass. The content ratio of these components is preferably 30% to 55% in total. In particular, when a high refractive index is required, it is preferably 33% or more, more preferably 35% or more, still more preferably 36% or more, still more preferably 37% or more, and particularly preferably 38% or more. On the other hand, if the high refractive index component is increased, devitrification is liable to occur. For applications requiring a lower surface roughness Ra, the content ratio of these components is more preferably 50% or less, still more preferably 45% or less, still more preferably 40% or less, and particularly preferably 35% or less.

Alkali metal component (Li)₂O+Na₂O+K₂O) is 0% to 10% in total. By increasing the alkali metal component, the Tg can be reduced. However, if Li₂O+Na₂O+K₂When O is too much, T is₁The viscosity curve tends to become steep, and the production characteristics tend to be lowered. On the other hand, if Li₂O+Na₂O+K₂If O is too small, T₁The melting temperature tends to be high, and coloring may occur. Thus, in the presence of Li₂O+Na₂O+K₂In the case of O, it is preferably 0.5% or more and 10% or less. Li₂O+Na₂O+K₂O is more preferably 1% or more, further preferably 1.5% or more, further preferably 2% or more, and particularly preferably 3% or more. In addition, Li₂O+Na₂O+K₂O is preferably 6% or less, more preferably 4% or less, further preferably 3% or less, and particularly preferably 2% or less.

Li₂The content ratio of O is 0% to 10%. Containing Li₂The content ratio of O is 0.2% to 10%. If containing Li₂O, the strength (Kc) and crack resistance (CIL) can be improved. The optical glass of the present invention contains Li₂In the case of O, the content ratio thereof is preferably 0.5% or more, more preferably 1% or more, further preferably 1.5% or more, and particularly preferably 2% or more. On the other hand, if Li₂When O is too large, devitrification is liable to occur. Particularly in the case where devitrification is a problem, Li₂The content ratio of O is preferably 6% or less, more preferably 3% or less, still more preferably 1% or less, and particularly preferably 0.1% or less.

In the case of chemically strengthening the optical glass of the present embodiment, Li₂The content ratio of O is preferably 3.0% or more, more preferably 6.0% or more, further preferably 9.0% or more, and particularly preferably 11.0% or more.

CaO is a component that suppresses devitrification, but if the amount of CaO is large, the crack resistance is liable to decrease. Therefore, the content ratio of CaO is preferably 0% or more and 25% or less. The content ratio of CaO is more preferably 20% or less, further preferably 17% or less, further preferably 14% or less, further preferably 13% or less, further preferably 12% or less, and particularly preferably 11.5% or less. The content ratio of CaO is more preferably 4% or more, further preferably 8% or more, further preferably 10% or more, and particularly preferably 11% or more.

SrO is a component for improving the meltability of glass, suppressing devitrification, and adjusting the optical constants of glass. On the other hand, if the amount of SrO increases, devitrification is promoted instead. Therefore, the content ratio of SrO is preferably 0% or more and 20% or less. The content ratio of SrO is more preferably 15% or less, still more preferably 12% or less, still more preferably 10% or less, still more preferably 9% or less, and particularly preferably 8% or less. The SrO content is more preferably 2% or more, still more preferably 5% or more, and particularly preferably 7% or more.

If the total amount of MgO, CaO and SrO is increased, the glass is easily devitrified. Therefore, the total amount of MgO, CaO and SrO is preferably 30% or less. More preferably 25% or less, still more preferably 22% or less, still more preferably 21% or less, still more preferably 20% or less, and particularly preferably 19.5% or less.

BaO is a component for suppressing devitrification, but if the amount of BaO is large, the density tends to be large. Therefore, when BaO is contained, it is preferably 0% or more and 30% or less. The content ratio of BaO is more preferably 20% or less, further preferably 15% or less, further preferably 11% or less, further preferably 9% or less, and particularly preferably 8% or less. The content ratio of BaO is more preferably 2% or more, further preferably 5% or more, and particularly preferably 7% or more.

The content ratio of the alkaline earth metal components (MgO + CaO + SrO + BaO) is 5% to 50% in total. If the total amount is 50% or less, devitrification of the glass can be suppressed, and therefore, it is preferable. More preferably 40% or less, further preferably 35% or less, further preferably 32% or less, further preferably 30% or less, further preferably 29% or less, further preferably 28% or less, and particularly preferably 20% or less. It is preferable that the total amount is 5% or more because the meltability of the glass can be improved. More preferably 10% or more, further preferably 15% or more, further preferably 20% or more, further preferably 25% or more, and particularly preferably 26% or more.

The specific gravity can be reduced by setting the ratio of BaO in the alkaline earth metal component (MgO + CaO + SrO + BaO) (BaO/(MgO + CaO + SrO + BaO)) to 0.5 or less. Preferably 0.45 or less, more preferably 0.42 or less, further preferably 0.40 or less, and particularly preferably 0.35 or less. By increasing the content of BaO in the alkaline earth metal component, the devitrification temperature can be lowered and the production characteristics can be improved. When the production characteristics are particularly important, the production characteristics are preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.25 or more, and particularly preferably 0.3 or more.

If the alkali metal component (Li)₂O+Na₂O+K₂O) and the total amount of the alkaline earth metal components (MgO + CaO + SrO + BaO) increase, the Tg of the glass tends to decrease. Therefore, the total amount of the alkali metal component and the alkaline earth metal component is preferably 30% or less, more preferably 29% or less, still more preferably 28% or less, and particularly preferably 27.5% or less.

TiO₂The content ratio of the component for increasing the dispersion of the glass to increase the refractive index of the glass is 0% to 50%. In the presence of TiO₂In the case of (3), the content ratio thereof is preferably 10% or more, more preferably 15% or more, further preferably 17% or more, further preferably 19% or more, further preferably 20% or more, and particularly preferably 20.5% or more. On the other hand, if TiO₂When the amount is too large, coloring tends to occur, and the transmittance decreases. Therefore, TiO particularly when transmittance is required₂The content ratio of (b) is preferably 50% or less, more preferably 40% or less, further preferably 30% or less, further preferably 25% or less, further preferably 23% or less, further preferably 22% or less, and particularly preferably 21% or less.

In the presence of B₂O₃In the case of (1), if TiO₂Relative to B₂O₃Specific ratio of TiO₂/B₂O₃If the glass is large, the melting temperature needs to be increased, so that Ti is easily reduced, the glass is easily colored, and the transmittance is easily lowered. Thus, in the presence of B₂O₃In the case of (2), TiO₂/B₂O₃Preferably 5.0 or less, more preferably 4.0 or less, further preferably 3.0 or less, further preferably 2.0 or less, further preferably 1.5 or less, further preferablyIt is preferably 1.2 or less, and particularly preferably 1.0 or less.

Nb₂O₅To improve the refractive index of glass and to reduce the Abbe number (v)_d) The composition of (1). Nb₂O₅The content ratio of (b) is 0% to 35%. Nb₂O₅The content ratio of (b) is preferably 0.5% or more, more preferably 1.0% or more, further preferably 1.5% or more, further preferably 2.0% or more, and particularly preferably 2.5% or more.

In addition, if Nb₂O₅Too much, it is easily devitrified. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less, and particularly preferably 3% or less.

If TiO is present₂、WO₃And Nb₂O₅When the total amount of (A) is small, the refractive index of the glass is lowered. Thus, TiO₂、WO₃And Nb₂O₅The total amount of (a) is preferably 10% to 50%. More preferably 14% or more, still more preferably 18% or more, still more preferably 22% or more, and particularly preferably 23% or more. On the other hand, if TiO₂、WO₃And Nb₂O₅If the total amount of (A) is large, devitrification is liable to occur. Therefore, for applications requiring a lower surface roughness Ra, it is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, and particularly preferably 25% or less.

ZrO₂The content ratio of the component for increasing the chemical durability of the glass to increase the refractive index of the glass is 0% to 20%. By containing ZrO₂The crack resistance can be improved. In the presence of ZrO₂In the case of (3), the content ratio thereof is more preferably 1% or more, still more preferably 2% or more, still more preferably 3% or more, and particularly preferably 4% or more. On the other hand, if ZrO₂Too much, it is easily devitrified. Therefore, particularly in the case where the production characteristics become important, ZrO₂The content ratio of (b) is more preferably 15% or less, still more preferably 10% or less, still more preferably 6% or less, and particularly preferably5% or less.

ZnO is a component for improving mechanical properties such as strength and crack resistance of the glass, and the content thereof is 0% to 15%. When ZnO is contained, the content ratio is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the amount of ZnO is large, devitrification is easy, and therefore the content ratio of ZnO is more preferably 10% or less, still more preferably 5% or less, still more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.5% or less.

La₂O₃The content ratio of the component for increasing the refractive index of the glass is 0% to 35%. In the presence of La₂O₃In the case of (3), the content ratio thereof is preferably 2% or more, more preferably 3% or more, further preferably 4% or more, further preferably 4.5% or more, and particularly preferably 5% or more. On the other hand, if La₂O₃When the amount of (B) is too large, mechanical properties are deteriorated and devitrification temperature is increased. Therefore, La is a material that is important for mechanical properties and manufacturing properties₂O₃The content ratio of (b) is preferably 30% or less. More preferably 25% or less, further preferably 20% or less, further preferably 15% or less, further preferably 10% or less, further preferably 7% or less, and particularly preferably 6% or less.

If Nb₂O₅、TiO₂、WO₃And Ta₂O₅The total amount of (A) to La₂O₃、Gd₂O₃、Y₂O₃And Yb₂O₃Ratio of the total amount of (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the transmittance is increased, the glass is easily colored and the transmittance is easily lowered. Thus, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 10.0 or less, more preferably 8.0 or less, further preferably 7.0 or less, further preferably 6.0 or less, further preferably 5.5 or less, and particularly preferably 5.0 or less. On the other hand, if (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) When the Tg of the glass is small, the Tg is liable to decrease. Therefore, for applications requiring high heat resistance, (Nb)₂O₅+TiO₂+WO₃+Ta₂O₅)/(La₂O₃+Gd₂O₃+Y₂O₃+Yb₂O₃) Preferably 0.5 or more, more preferably 1.0 or more, further preferably 2.0 or more, further preferably 3.0 or more, and particularly preferably 4.0 or more.

The optical glass obtained from glass composition A3 has a high refractive index (n) in the range of 1.81-1.96_d). Refractive index (n)_d) Is 1.81 or more. The optical glass is suitable as an optical glass for use in wearable devices in view of widening the angle of an image, increasing brightness and contrast, improving light guiding characteristics, improving ease of processing a diffraction grating, and the like. Further, a small-sized imaging glass lens having a wide imaging angle, which is used for applications such as an in-vehicle camera and a robot vision sensor, is preferable because it is smaller and has a wider imaging range. The refractive index (n)_d) Preferably 1.820 or more, more preferably 1.830 or more, further preferably 1.835 or more, further preferably 1.840 or more, further preferably 1.845 or more, and particularly preferably 1.850 or more.

On the other hand, refractive index (n)_d) A glass exceeding 1.96 tends to have a high density and a high devitrification temperature. In particular, when the density of the optical glass is regarded as high or low, the refractive index (n) is set_d) Preferably 1.92 or less, more preferably 1.90 or less, further preferably 1.89 or less, further preferably 1.88 or less, further preferably 1.87 or less, further preferably 1.86 or less, further preferably 1.855 or less, further preferably 1853 or less.

In addition, the optical glass obtained from glass composition A3 had a glass density of 3.3g/cm³Above and 5.4g/cm³The following density (d). By having the density in the above range, the optical glass can provide a satisfactory wearing feeling for a user when used in wearable equipment, and can reduce the weight of the entire device when used in an in-vehicle camera, a robot vision sensor, or the like. The density (d) is preferably 5.2g/cm³Hereinafter, more preferably 5.0g/cm³Hereinafter, more preferably 4.6g/cm³Hereinafter, more preferably 4.2g/cm³Hereinafter, more preferably 4.1g/cm³Hereinafter, more preferably 4.0g/cm³The following.

On the other hand, in order to make the surface of the optical glass less likely to be scratched, the density (d) is preferably 3.6g/cm³The above. More preferably 3.7g/cm³Above, more preferably 3.8g/cm³Above, it is more preferably 3.9g/cm³Above, 3.95g/cm is particularly preferable³The above.

The optical glass has a devitrification temperature of 1300 ℃ or lower. With such characteristics, devitrification of the glass during molding can be suppressed, and the moldability is good. The devitrification temperature is more preferably 1275 ℃ or lower, still more preferably 1240 ℃ or lower, still more preferably 1225 ℃ or lower, still more preferably 1200 ℃ or lower, still more preferably 1175 ℃ or lower, still more preferably 1150 ℃ or lower, still more preferably 1100 ℃ or lower, still more preferably 1050 ℃ or lower, still more preferably 1025 ℃ or lower, and particularly preferably 1020 ℃ or lower. Here, the devitrification temperature is the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more are not visible on the surface and inside of the glass when the heated and melted glass is cooled by natural cooling.

[ method for producing optical glass and glass molded article ]

The optical glass of the present invention is produced, for example, as follows. That is, first, the raw materials are weighed so as to have the above-mentioned predetermined glass composition, and uniformly mixed. The prepared mixture was put into a platinum crucible, a quartz crucible, or an alumina crucible to be roughly melted. Thereafter, the resultant is put into a gold crucible, a platinum alloy crucible, a reinforced platinum crucible or an iridium crucible, melted at a temperature of 1200 to 1400 ℃ for 2 to 10 hours, homogenized by deaeration, stirring or the like, defoamed or the like, and then cast into a mold to be slowly cooled. The optical glass of the present invention is thus obtained.

The optical glass may be formed into a glass plate by forming a molten glass into a plate shape by a forming method such as a float method, a melting method, or a flattening method. Alternatively, the molten glass may be formed into a lump and then formed into a glass sheet by a redraw method or the like. Further, the glass molded product can be produced by, for example, reheating press molding, precision press molding or the like. That is, a lens preform for press molding is produced from an optical glass, and the lens preform is heated and pressure-molded again and then polished to produce a glass molded body, or for example, a lens preform produced by polishing is precisely pressure-molded to produce a glass molded body. The method for producing the glass molded article is not limited to these methods.

The residual bubbles in the optical glass of the present invention produced as described above are preferably 10 bubbles per 1kg (10 bubbles/kg) or less, more preferably 7 bubbles/kg or less, still more preferably 5 bubbles/kg or less, and particularly preferably 3 bubbles/kg or less. When the glass plate is molded by the above method, if the residual bubbles are 10 bubbles/kg or less, the glass plate containing no bubbles can be efficiently molded. When the diameter of the circle of the smallest dimension enclosing the residual bubbles 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, still more preferably 40 μm or less, and particularly preferably 20 μm or less.

The diameter is defined as the longitudinal length L of the residual bubbles₁The length of a straight line which is the maximum length of the residual bubbles on a straight line perpendicularly intersecting the diameter is set as the transverse length L of the residual bubbles₂When the shape of the residual bubble is expressed by the aspect ratio, L is₂/L₁Preferably 0.90 or more, more preferably 0.92 or more, and still more preferably 0More than 95. Thus if L is₂/L₁When the residual bubble content is 0.90 or more, the residual bubble is in a state close to a perfect circle (perfect sphere), and even if the residual bubble is contained, for example, the strength of the glass can be suppressed from being lowered as compared with the elliptical residual bubble, and the generation of a crack from which the residual bubble becomes a starting point can be suppressed when the glass sheet is manufactured. Even if residual bubbles are present in the glass substrate, the effect of suppressing anisotropic scattering of light incident on the glass plate is exhibited as compared with the residual bubbles having an elliptical shape. The size and shape of the residual bubbles can be obtained from the values measured by a laser microscope (product of KEYENCE GmbH: VK-X100).

Optical members such as glass plates and glass moldings produced in this manner are useful for various optical elements. Among them, the present invention is particularly suitable for (1) light guides, filters, lenses, and the like used in wearable devices such as glasses with projectors, glasses-type or goggle-type displays, virtual reality augmented reality display devices, virtual image display devices, and the like, and (2) lenses, cover glasses, and the like used in-vehicle cameras, vision sensors for robots, and the like. And is also suitable for applications exposed to severe environments such as vehicle-mounted cameras. Further, the present invention is also applicable to applications such as a glass substrate for organic EL, a substrate for wafer level lens array, a substrate for lens unit, a lens forming substrate by etching, and an optical waveguide.

The optical glass of the present embodiment described above has a high refractive index and a low density, has good manufacturing characteristics, and is suitable as an optical glass for wearable devices, vehicles, and robots. SiO is formed on the main surface of the optical glass₂Film of equal low refractive index and TiO₂The optical member of the antireflection film composed of 4 to 10 dielectric multilayer films in which high refractive index films are alternately laminated is also suitable for wearable devices, vehicles, and robots.

Examples

The raw materials were weighed so as to have chemical compositions (mol% in terms of oxides) shown in tables 1 to 9. The raw materials are selected from high-purity raw materials used for general optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. corresponding to the raw materials of the respective components.

The weighed raw materials were uniformly mixed, placed in a platinum crucible having an internal volume of about 300mL, melted at about 1300 ℃ for about 2 hours, clarified, stirred, then kept at 1300 ℃ for 0.5 hour, cast into a rectangular mold having a length of 50mm × a width of 100mm preheated to about 650 ℃, and then slowly cooled at about 1 ℃/min to prepare samples of examples 1 to 85. Here, examples 1 to 80 are examples, and examples 81 to 85 are comparative examples.

[ evaluation ]

The refractive index (n) of each sample obtained above was measured as follows_d) Density (d), devitrification temperature, viscosity (viscosity of glass is 10)¹Temperature T at dPa · s₁). The results are shown in tables 1 to 9.

Refractive index (n)_d): the glass of the sample was processed into a triangular prism having a side of 30mm and a thickness of 10mm, and measured by a refractometer (manufactured by Kalnew Co., Ltd., machine name: KPR-2000).

Density (d): the measurement was carried out according to JIS Z8807(1976, measurement method by weighing in liquid).

Devitrification temperature: about 5g of the sample was put into a platinum dish, and the sample was held at 1000 to 1400 ℃ for 1 hour at 5 ℃ intervals, and after cooling the sample by natural cooling, the sample was observed by a microscope for the presence or absence of crystal precipitation, and the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more were not observed was regarded as the devitrification temperature.

Temperature T₁: the viscosity of the glass was measured using a rotational viscometer in accordance with the method specified in ASTMC965-96, and the viscosity of the glass was measured to be 10¹Temperature T at dPa · s₁(℃)。

Glass transition temperature (Tg): the value was measured using a differential thermal expansion meter (TMA) and determined according to JIS R3103-3 (2001).

Young's modulus (E): a plate-like sample of 20 mm. times.20 mm. times.1 mm was measured (unit: GPa) using an ultrasonic precision plate thickness gauge (MODEL 38DL PLUS, manufactured by OLYMPAS).

LTV: the thickness of a glass substrate was measured at 3mm intervals on a plate-like sample of 50mm × 50mm × 1mm using a non-contact laser displacement meter (NanoMetro manufactured by Takara Shuzo) to calculate LTV.

Warping: the heights of 2 main surfaces of the glass substrate were measured at 3mm intervals for disk-shaped samples having a diameter of 8 inches × 1mm and a diameter of 6 inches × 1mm using a non-contact laser displacement meter (NanoMetro manufactured by black field precision), and the warpage was calculated by the above-described method described with reference to fig. 1.

Surface roughness (Ra): the area of 10. mu. m.times.10 μm was measured on a plate-like sample of 20 mm. times.20 mm. times.1 mm using an Atomic Force Microscope (AFM) (manufactured by Oxford Instruments).

Abbe number (v)_d): using the sample used in the above refractive index measurement, passing v_d＝(n_d－1)/(n_F－n_C) And (6) calculating. n is_dIs the refractive index with respect to the helium d-line, n_FIs the refractive index with respect to the hydrogen F line and n_CIs the refractive index relative to the hydrogen C line. These refractive indices were also measured using the refractometer described above.

Coefficient of thermal expansion (α): the linear thermal expansion coefficient in the range of 30 to 350 ℃ was measured using a differential thermal expansion meter (TMA), and the average linear thermal expansion coefficient in the range of 30 to 350 ℃ was determined according to JIS R3102 (1995).

[ Table 1]

TABLE 1

[ Table 2]

TABLE 2

[ Table 3]

TABLE 3

[ Table 4]

TABLE 4

[ Table 5]

TABLE 5

[ Table 6]

TABLE 6

[ Table 7]

TABLE 7

[ Table 8]

TABLE 8

[ Table 9]

TABLE 9

The optical glasses of the above examples (examples 1 to 80) all had a refractive index (n)_d) A high refractive index of 1.81 or more. In addition, the density is as low as 6.0g/cm³The following. Further, the viscosity of the glass became 10¹Temperature T at dPa · s₁Has a temperature of 900 to 1200 ℃ and thus has good manufacturing characteristics. Further, the devitrification temperature is 1300 ℃ or lower, and therefore, the production characteristics are good. Therefore, it is suitable for wearable equipment, vehicle-mounted camera,Optical glass used in robot vision.

On the other hand, the glass of examples 81 and 84 as comparative examples had a devitrification temperature higher than 1300 ℃ and had poor production characteristics. The refractive index (nd) of the glasses of examples 81, 82 and 83 was less than 1.81. The glass of example 85 had a Si content of less than 5 mol%.

The glass compositions of the above examples (examples 1 to 80) were melted, and the temperature T of the optical glass obtained from the molten glass₁The temperature is 900 to 1200 ℃, so the manufacturing characteristic is good, the size of the residual bubbles is small, and the number of the residual bubbles is small, so the glass plate without the defects of bubbles, foreign matters, stripes, phase separation and the like can be obtained. Therefore, when a sample having the above size is formed, an optical glass having an LTV value of 2 μm or less, a warpage value (a 6-inch diameter circular glass plate) of 30 μm or less, and an Ra value of 2nm or less can be obtained. Further, since the devitrification temperature is 1300 ℃ or lower and the occurrence of devitrification can be suppressed, it is considered that the LTV value is 1.5 μm or lower, the warpage value (6-inch diameter circular glass plate) is 18 μm or lower, and the Ra value is 1nm or lower.

As a result of precision polishing of 3 kinds of glass plates of this example which did not have the above-mentioned disadvantages, values of LTV of 1.0, 1.2 and 1.2 μm, values of warpage of 45, 32 and 38 and values of Ra of 0.198, 0.284 and 0.266 were obtained. Therefore, by precisely polishing the glass plate of the example of the present invention which does not have the above-mentioned disadvantages, it is possible to obtain an optical glass having an LTV value of 2 μm or less, a warpage value of 50 μm or less, and an Ra value of 2nm or less.

In the case of chemically strengthening the glass of the present invention, for example, the glass may be immersed in a molten solution in which a sodium nitrate salt is heated to 400 ℃ and melted for 30 minutes, and then chemically strengthened to obtain a strengthened glass.

As described above, the optical glass of the present invention has a high refractive index and a low density, has good production characteristics, and is suitable as an optical glass for wearable devices, vehicles, robots, and the like. The optical glass of the above embodiment is formed by mixing SiO₂Film of equal low refractive index and TiO₂4-10 layers of dielectric formed by alternately laminating films having high refractive indexThe optical member of the antireflection film composed of a multilayer film is also suitable for wearable devices, vehicles, and robots.

The present invention has been described in detail with reference to specific embodiments, but 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 invention. The present application is based on japanese patent applications published on 31/8/2018 (japanese patent application 2018-163582), and 21/11/2018 (japanese patent application 2018-218577), the contents of which are incorporated herein by reference.