WO2022230535A1

WO2022230535A1 - Glass, optical glass, and optical element

Info

Publication number: WO2022230535A1
Application number: PCT/JP2022/015038
Authority: WO
Inventors: 菜那岩▲崎▼; 健介鈴木
Original assignee: 株式会社オハラ
Priority date: 2021-04-27
Filing date: 2022-03-28
Publication date: 2022-11-03
Also published as: JPWO2022230535A1

Abstract

The present invention more simply prepares and stably provides glass having higher impact resistance than in the prior art. Provided is glass in which, in mass% in terms of oxides, the mass sum SiO₂+B₂O₃+Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃ is 50.0% or greater (however, the SiO₂ component is 22.0% or less), the mass ratio Al₂O₃/(SiO₂+B₂O₃) is 0.01 or greater, the BaO content is 10.0% or lower, and the ratio β/α of β to α is 7.80 or greater, where α is the average linear expansion coefficient at 100-300°C and β is the Knoop hardness.

Description

Glass, optical glass and optical elements

The present invention relates to glass, optical glass and optical elements.

In recent years, the demand for glass for automotive applications has increased. For example, conventional rear view cameras only project images behind the vehicle when the vehicle is put into a garage, etc. It became possible to project the image of Also, with the development of artificial intelligence and sensor technology, cars equipped with automatic driving systems are appearing. Such glass is mainly installed outside the vehicle body in many cases, and with the development of automobile technology, there is a demand for glass suitable for use outside the vehicle.

　In-vehicle glass, which may be installed in multiple locations, is exposed to various impacts. During driving, the size of flying objects such as dust and pebbles caught in the air by the tires and the speed of the vehicle change the impact on the glass, so it is necessary to have extremely high strength.

The Knoop hardness of JOGIS is known as an indicator of the hardness of glass, and can also be used as an indicator of glass with high mechanical durability. As a material used for in-vehicle applications, for example, a glass composition as typified by Patent Document 1 is known.

JP 2013-256446 A

However, the glass disclosed in Patent Document 1 is an invention in which it was found that the moldability of the lens can be improved by increasing the Knoop hardness, and the increased hardness of the glass makes the glass lens less likely to be scratched. However, it cannot be said that the impact resistance is sufficient.

　Tempered glass is an example of glass with high strength. Tempered glass has excellent strength because it has a compressive stress layer on the glass surface. Chemical strengthening or the like is required, which complicates the manufacturing process. Also, it is necessary to introduce an alkaline component for ion exchange, which deteriorates the impact resistance.

The present invention has been made in view of the above problems, and its purpose is to simply produce glass with higher impact resistance than conventional glass and to stably provide it.

In order to solve the above problems, the present inventors have conducted intensive testing and research, and found that while suppressing the contents of the SiO ₂ component and the BaO component, the SiO ₂ component, the B ₂ O ₃ component, and the Al ₂ O ₃ component , La ₂ O ₃ component, Y ₂ O ₃ component, and Gd ₂ O ₃ component, and adjusting the mass ratio of Al ₂ O ₃ component to SiO ₂ component and B ₂ O ₃ component to 0.01 or more, When the average linear expansion coefficient α at 100 to 300 ° C. and the Knoop hardness are β, by setting β / α, which is the ratio of β to α, to 7.80 or more, a highly stable and impact-resistant glass material found that it is possible to create, and completed the present invention. Specifically, the present invention provides the following.

(1) in mass % based on oxides,
mass sum of SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ +La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ is 50.0% or more (however, the SiO ₂ component is 22.0% or less);
mass ratio Al ₂ O ₃ /(SiO ₂ +B ₂ O ₃ ) is 0.01 or more;
BaO content is 10.0% or less,
and
When the average linear expansion coefficient α at 100 to 300 ° C. and the Knoop hardness are β,
A glass in which β/α, which is the ratio of β to α, is 7.80 or more.

(2) The glass according to (1), wherein the mass sum of Nb ₂ O ₅ +WO ₃ is 10.0% or less.

(3) The glass according to (1) or (2), wherein the mass ratio TiO ₂ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is 0.20 or more.

(4) Mass ratio Gd ₂ O ₃ /Ln ₂ O ₃ is 0.10 or less (Ln is one or more selected from the group consisting of La, Y, Gd and Yb)
The glass according to (1) to (3).

(5) Knoop hardness is grade 6 or higher,
The glass according to (1) to (4), which has an average linear expansion coefficient α of 90×10 ^-7 ° C. ^-1 or less at 100 to 300°C.

(6) Optical glass made of the glass according to any one of (1) to (5).

(7) An optical element made of the glass described in (6).

The present invention provides a glass, optical glass, and optical element having better impact resistance than conventional glass by adjusting each component and adjusting the ratio between the average linear expansion coefficient α and the Knoop hardness at 100 to 300 ° C. can be obtained.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is by no means limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be suitably omitted about the part which description overlaps, it does not limit the gist of invention.

[Glass component]
The composition range of each component constituting the glass of the present invention is described below. Unless otherwise specified in this specification, the content of each component is expressed in % by mass with respect to the total mass of the glass in terms of oxide composition. Here, the term "composition converted to oxide" means that, when it is assumed that oxides, composite salts, metal fluorides, etc. used as raw materials for the constituent components of the glass of the present invention are all decomposed and changed into oxides when melted, It is a composition in which each component contained in the glass is expressed with the total mass of the produced oxide being 100% by mass.

The _SiO2 component is a component that can increase the viscosity of the molten glass and increase the hardness of the glass. It is also a component that enhances the stability of the glass and makes it easier to obtain a glass that can withstand mass production. Therefore, the lower limit of the content of the _SiO2 component is preferably more than 0%, more preferably 2.0% or more, more preferably 4.0% or more.
On the other hand, by setting the content of the SiO ₂ component to 22.0% or less, the deterioration of the impact resistance of the glass can be suppressed. In particular, the SiO ₂ component is inferior to the B ₂ O ₃ component and the Al ₂ O ₃ component, which will be described later, in impact resistance. Therefore, the upper limit of the content of the _SiO2 component is preferably 22.0% or less, more preferably 21.0% or less, still more preferably 18.0% or less, still more preferably 16.0% or less.

The B ₂ O ₃ component is a component that becomes a glass-forming oxide in the glass of the present invention containing a large amount of rare earth oxides. In particular, by adjusting the content of the B ₂ O ₃ component, the devitrification resistance of the glass can be enhanced and the meltability of the glass can be enhanced. Also, when increasing the rare earth elements, the more the B ₂ O ₃ component is, the more stable the glass becomes. Therefore, the lower limit of the content of the B ₂ O ₃ component is preferably more than 0%, more preferably 1.5% or more, still more preferably 2.0% or more, and still more preferably 3.5% or more.
On the other hand, the content of the B ₂ O ₃ component is preferably 20.0% or less, more preferably 18.0% or less, more preferably 16.0% or less, and still more preferably 15.0% or less. do.

The Al ₂ O ₃ component is a component that, when included, forms a strong bond, suppresses the thermal expansion of the glass, and improves the devitrification resistance of the molten glass. The Al ₂ O ₃ component is the component that maximizes the impact resistance when compared with the SiO ₂ component and the B ₂ O ₃ component. Therefore, the lower limit of the content of the Al ₂ O ₃ component is preferably 0.1% or more, more preferably 0.3% or more, still more preferably 0.5% or more, and still more preferably 0.8% or more. .
On the other hand, the content of the Al ₂ O ₃ component is preferably 15.0% or less, more preferably 13.0% or less, even more preferably 12.0% or less, still more preferably 10.0% or less, and even more preferably is 7.0% or less, more preferably 6.0% or less, more preferably 5.0% or less.

The TiO ₂ component is a component that increases the refractive index of the glass, increases the Abbe's number, and increases the hardness of the glass. In particular, by adjusting the content of the TiO ₂ component, devitrification due to excessive content can be reduced, and the transmittance in the infrared region can be increased. Cameras for in-vehicle use should preferably have high transmittance in the infrared region because they need to be used day and night. The lower limit of the TiO ₂ component content is preferably 3.0% or more, more preferably 4.5% or more, still more preferably 6.0% or more, and still more preferably 7.0% or more.
On the other hand, the upper limit of the content of the TiO ₂ component is preferably 28.0% or less, more preferably 26.0% or less, still more preferably 24.0% or less, and even more preferably 22.0% or less.

The La ₂ O ₃ component is a component that increases the refractive index and Abbe number of the glass while increasing the Knoop hardness. Therefore, the content of the La ₂ O ₃ component is preferably 18.0% or more, more preferably 20.0% or more, still more preferably 24.0% or more, and still more preferably 30.0% or more. .
On the other hand, by setting the content of the La ₂ O ₃ component to 55.0% or less, devitrification can be reduced by increasing the stability of the glass, and an unnecessary increase in the Abbe number can be suppressed. The upper limit is 55.0% or less, more preferably 53.0% or less, still more preferably 51.0% or less, still more preferably 48.0% or less, and even more preferably 45.0% or less.

The Y ₂ O ₃ component is a component capable of increasing the stability of the glass by improving the meltability of the raw material for glass while suppressing the material cost of the glass while maintaining the desired refractive index and Abbe number.
The upper limit of the content of the _three Y ₂ O components is preferably 15.0% or less, more preferably 12.0% or less, and still more preferably 10.0% or less.
On the other hand, the lower limit of the content of the Y ₂ O ₃ component is preferably 0.1% or more, preferably 0.5% or more, and more preferably 1.0% or more.

The Gd ₂ O ₃ component and the Yb ₂ O ₃ component are components capable of increasing the refractive index of the glass. However, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component are expensive as raw materials, and if the content is large, the production cost will be high. Therefore, the contents of the _three Gd ₂ O components and the _three Yb ₂ O components are each preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, still more preferably 0.0% or less. 8% or less, more preferably 0.5% or less, still more preferably 0.3% or less, further preferably 0.1% or less. In particular, from the viewpoint of reducing material costs, it is most preferable not to contain these components.

The ZnO component is a component that increases the meltability of the raw material, increases the hardness of the glass, and increases the stability of the glass. It is also a component that contributes to the improvement of impact resistance. The lower limit of the ZnO component content is preferably more than 0%, more preferably 0.5% or more, and still more preferably 1.0% or more. On the other hand, by setting the content of the ZnO component to 25.0% or less, it is possible to suppress a decrease in the refractive index of the glass and reduce devitrification due to an excessive decrease in viscosity. Therefore, the upper limit of the content of the ZnO component is preferably 25.0% or less, more preferably 23.0% or less, and more preferably 21.0% or less.

The MgO component is an optional component that can improve the meltability of glass raw materials and the devitrification resistance of glass. On the other hand, by setting the content of the MgO component to 8.0% or less, it is possible to suppress a decrease in impact resistance, a decrease in refractive index, and a decrease in devitrification resistance due to an excessive content. Therefore, the upper limit of the content of the MgO component is preferably 8.0% or less, more preferably 6.0% or less, still more preferably 4.0% or less, still more preferably 3.0% or less.

The CaO component is an optional component capable of increasing the hardness and impact resistance of the glass and improving the meltability of the glass raw material. Among the alkaline earth components, it is the most effective component for improving impact resistance.
The lower limit of the CaO component content is preferably more than 0%, more preferably 0.5% or more, and still more preferably 1.0% or more. On the other hand, by setting the content of the CaO component to 20.0% or less, it is possible to suppress the decrease in the refractive index and the devitrification resistance due to the excessive content of these components. Therefore, the upper limit of the CaO content is preferably 20.0% or less, more preferably 18.0% or less, still more preferably 15.0% or less, still more preferably 13.0% or less.

The SrO component is an optional component that can improve the meltability of glass raw materials and the devitrification resistance of glass. On the other hand, by setting the content of the SrO component to 8.0% or less, it is possible to suppress a decrease in refractive index and a decrease in devitrification resistance due to an excessive content of these components. Therefore, the upper limit of the SrO component content is preferably 8.0% or less, more preferably 6.0% or less, still more preferably 4.0% or less, and still more preferably 3.0% or less.

The BaO component is a component that increases the refractive index and Abbe number of the glass and lowers the liquidus temperature. On the other hand, the BaO component reduces the impact resistance of the glass the most among the alkaline earth metals. Therefore, the content of the BaO component is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, still more preferably 3.0% or less, still more preferably 1.0%. % or less is the upper limit.

The Li ₂ O component, Na ₂ O component and K ₂ O component are components capable of improving the meltability of the glass and lowering the glass transition point. On the other hand, by making the Li ₂ O component, the Na ₂ O component, and the K ₂ O component each 5.0% or less, it becomes difficult to lower the refractive index of the glass, and the devitrification of the glass can be reduced. decrease in hardness can be suppressed. Therefore, the contents of the Li ₂ O component, the Na ₂ O component and the K ₂ O component are each preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, still more preferably is 2.0% or less, more preferably 1.0% or less, more preferably 0.8% or less, still more preferably 0.6% or less, and still more preferably 0.3% or less.

The ZrO ₂ component is a component capable of increasing the refractive index Abbe number while suppressing coloration. Therefore, the lower limit is preferably more than 0%, more preferably 0.5% or more, and still more preferably 1.0% or more.
On the other hand, the ZrO ₂ component causes devitrification when contained excessively. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 8.0% or less, more preferably 6.0% or less, and still more preferably 4.0% or less.

The Nb ₂ O ₅ component is an optional component that can increase the refractive index of the glass. On the other hand, by setting the content of the Nb ₂ O ₅ component to 5.0% or less, the material cost of the glass can be suppressed. Also, devitrification due to excessive Nb ₂ O ₅ component content can be reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably 5.0% or less, more preferably 4.0% or less, still more preferably 3.0% or less, still more preferably 2.0% or less, further preferably The upper limit is 1.0% or less, more preferably 0.8% or less, more preferably 0.5% or less, still more preferably 0.3% or less, and even more preferably 0.1% or less. In particular, from the viewpoint of reducing material costs, the Nb ₂ O ₅ component may not be contained.

The WO ₃ component is a component that can increase the refractive index, improve the resistance to devitrification, and increase the meltability in a small amount. On the other hand, by setting the content of the _three WO components to 5.0% or less, the material cost of the glass can be suppressed. Therefore, the content of the _three WO components is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, still more preferably 2.0% or less, and still more preferably 1.0% or less. The upper limit is 0% or less, more preferably 0.8% or less, more preferably 0.5% or less, still more preferably 0.3% or less, and even more preferably 0.1% or less. In particular, from the viewpoint of reducing material costs, it is most preferable not to contain ₃ WO components.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance. Also, by setting the content of the Ta ₂ O ₅ component to 5.0% or less, the melting temperature of the raw material is lowered, and the energy required for melting the raw material is reduced, so that the manufacturing cost of the glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 5.0% or less, more preferably 3.0% or less, still more preferably 1.0% or less, still more preferably 0.5% or less, further preferably 0.1% or less. In particular, from the viewpoint of reducing material costs, it is most preferable not to contain the Ta ₂ O ₅ component.

The P ₂ O ₅ component is a component capable of lowering the liquidus temperature of the glass to improve devitrification resistance. The upper limit of the content of the P ₂ O ₅ component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and still more preferably 0.8% or less.

The content of the _three Bi ₂ O components is preferably 3.0% or less, more preferably 1.0% or less, still more preferably 0.8% or less, still more preferably 0.5% or less, still more preferably 0.5% or less. The upper limit is 3% or less, most preferably 0.1% or less.

The content of component F is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, and still more preferably 0.3% or less. is the upper limit, but it may be 0%.

The content of TeO ₂ component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, but the upper limit is 0% may be

The upper limit of the content of Ga ₂ O ₃ component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and still more preferably 0.5% or less, It may be 0%.

The content of GeO ₂ component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, but the upper limit is 0% may be

The content of the CeO ₂ component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, but the upper limit is 0% may be

The content of the HfO ₂ component is preferably 0.5% or less, more preferably 0.1% or less, more preferably 0.05% or less, and most preferably substantially free.

The upper limit of the SnO ₂ component content is preferably 2.0% or less, more preferably 1.0% or less, and still more preferably 0.5% or less, but may be 0%.

The Sb ₂ O ₃ component is an optional component capable of defoaming the glass melt when it is contained in an amount exceeding 0.0%.
On the other hand, if the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region will deteriorate. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, more preferably 0.5% or less, still more preferably 0.3% or less.

The component for fining and defoaming the glass is not limited to the above Sb ₂ O ₃ component, and any known fining agent, defoaming agent or combination thereof in the field of glass production can be used.

By setting the mass sum SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ +La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ to 50.0% or more, the structure of the glass can be strengthened and the hardness of the glass can be increased. However, when trying to strengthen the impact resistance while increasing the rare earth oxide component _, the _SiO2 component is a component that lowers the impact resistance of the glass compared to _B2O3 and _Al2O3 _. , the content is preferably 22.0% or less. The preferred range of the content of the _SiO2 component is as described above. The mass sum of SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ +La ₂ O ₃ +Y ₂ O ₃ +Gd ₂ O ₃ is preferably 50.0% or more, more preferably 53.0% or more, still more preferably 55.0%. Above, preferably 57.0% or more, more preferably 58.0% or more, is the lower limit.

By setting the mass ratio Al ₂ O ₃ /(SiO ₂ +B ₂ O ₃ ) to 0.01 or more, the structure of the glass is strengthened and the coefficient of thermal expansion can be reduced. Al ₂ O ₃ component _, SiO ₂ component, and _B ₂ O ₃ component can strengthen the glass structure. The mass ratio Al ₂ O ₃ /(SiO ₂ +B ₂ O ₃ ) is preferably 0.01 or more, more preferably 0.015 or more, still more preferably 0.02 or more, still more preferably 0.03 or more, and still more preferably has a lower limit of 0.04 or more.
On the other hand, by setting the mass ratio Al ₂ O ₃ /(SiO ₂ +B ₂ O ₃ ) to 0.500 or less, deterioration of the meltability can be suppressed while maintaining the impact resistance of the glass. The upper limit of the mass ratio Al ₂ O ₃ /(SiO ₂ +B ₂ O ₃ ) is preferably 0.500 or less, more preferably 0.400 or less, and still more preferably 0.350 or less.

By setting the mass sum Nb ₂ O ₅ +WO ₃ to 10.0% or less, it is possible to suppress raw material costs while enhancing the stability of the glass. Therefore, Nb ₂ O ₅ +WO ₃ is preferably 10.0% or less, more preferably 5.0% or less, still more preferably 3.0% or less, still more preferably 2.0% or less, further preferably 1.0% or less. The upper limit is 0% or less.

By setting the mass ratio TiO ₂ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) within a desired range, it is possible to increase the impact resistance while increasing the hardness of the glass and suppressing devitrification due to TiO ₂ components. can. The mass ratio TiO ₂ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is preferably 0.20 or more, more preferably 0.25 or more, still more preferably 0.29 or more, still more preferably 0.35 or more, More preferably, the lower limit is 0.40 or more. On the other hand, the mass ratio TiO ₂ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is preferably 1.20 or less, more preferably 1.00 or less, still more preferably 0.90 or less, still more preferably 0.90 or less. The upper limit is 75 or less.

By setting the mass ratio Gd ₂ O ₃ /Ln ₂ O ₃ to 0.10 or less, production costs can be suppressed (Ln is at least one selected from the group consisting of La, Y, Gd, and Yb). By adjusting the content of the Gd ₂ O ₃ component with respect to the rare earth oxide, it is possible to relatively reduce the content of the Gd ₂ O ₃ component. The mass ratio Gd ₂ O ₃ /Ln ₂ O ₃ is preferably 0.10 or less, more preferably 0.07 or less, still more preferably 0.06 or less, still more preferably 0.03 or less, still more preferably 0.02. Up to the following.

By setting the mass ratio B ₂ O ₃ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) to 0.10 or more, the meltability can be improved and the rare earth oxide can be stably introduced. The lower limit of the mass ratio B ₂ O ₃ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is preferably 0.10 or more, more preferably 0.15 or more, and still more preferably 0.17 or more. On the other hand, when the mass ratio B ₂ O ₃ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is 2.00 or less, deterioration of acid resistance can be suppressed. The mass ratio B ₂ O ₃ /(SiO ₂ +B ₂ O ₃ +Al ₂ O ₃ ) is preferably 2.00 or less, more preferably 1.96 or less, still more preferably 1.93 or less, still more preferably 1.90. Up to the following.

By setting the mass sum CaO + ZnO to 5.0 or more, it is possible to maintain the meltability and hardness of the glass and obtain a glass with high impact resistance. Alkaline earth metals are components that lower the hardness of the glass and increase the thermal expansion. can. The lower limit of the mass sum CaO+ZnO is preferably 5.0% or more, more preferably 7.0% or more, still more preferably 10.0% or more, and still more preferably 13.0% or more. On the other hand, the upper limit of the mass sum CaO+ZnO is preferably 23.0% or less, more preferably 21.0% or less, and even more preferably 20.0% or less.

By setting the mass ratio (B ₂ O ₃ +Al ₂ O ₃ )/(La ₂ O ₃ +Y ₂ O ₃ ) in the range of 0.300 to 0.450, the coefficient of thermal expansion can be reduced while maintaining the refractive index. It becomes possible to increase the hardness of the glass. Although the B ₂ O ₃ component and the Al ₂ O ₃ component can increase the hardness of the glass, it becomes difficult to maintain the refractive index when the content is large. Therefore, by including La ₂ O ₃ and Y ₂ O ₃ and adjusting the contents of the components, it is possible to increase the hardness of the glass with a small coefficient of thermal expansion while maintaining the refractive index. The mass ratio (B ₂ O ₃ +Al ₂ O ₃ )/(La ₂ O ₃ +Y ₂ O ₃ ) is preferably 0.300 or more, more preferably 0.315 or more, still more preferably 0.320 or more, still more preferably has a lower limit of 0.325 or more. On the other hand, the mass ratio (B ₂ O ₃ +Al ₂ O ₃ )/(La ₂ O ₃ +Y ₂ O ₃ ) is preferably 0.450 or less, more preferably 0.440 or less, still more preferably 0.420 or less. , more preferably 0.418 or less.

<Ingredients that should not be contained>
Next, components that should not be contained in the glass of the present invention and components that are not preferable to be contained will be described.

Other components can be added as necessary within a range that does not impair the properties of the glass of the present invention. However, each transition metal component such as Nd, V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb and Lu, is Even if a small amount of is contained alone or in combination, the glass will be colored and have the property of causing absorption at specific wavelengths in the visible range. preferable.

In addition, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with a high environmental load, it is desirable that they are not substantially contained, that is, they are not contained at all except for unavoidable contamination.

In addition, Th, Cd, Tl, Os, Be, and Se components have recently tended to refrain from being used as hazardous chemical substances. Environmental measures are required up to the present. Therefore, it is preferable not to contain these substantially when environmental influence is emphasized.

<Physical properties>
The glass of the present invention is preferably grade 6 or higher in a measuring method according to "JOGIS09-2019 Method for measuring Knoop hardness of glass". As a result, the glass is hardened, so that scratches and cracks during polishing of the glass and scratches on the surface during transportation of the glass are less likely to occur. A glass that is easy to maintain can be obtained. Therefore, the Knoop hardness of the glass of the present invention is preferably grade 6 or higher, more preferably grade 7 or higher. Furthermore, the Knoop hardness of the glass of the present invention is preferably 600 or more. The Knoop hardness can be represented by a grade, and even in the range of 550 to 650 where the Knoop hardness is grade 6, it is more preferably 600 or more. The lower limit of the Knoop hardness of the glass of the present invention is preferably 600 or higher, more preferably 620 or higher, and still more preferably 650 or higher. Although the upper limit of the Knoop hardness of the glass of the present invention is not particularly limited, the upper limit of the Knoop hardness of the glass of the present invention may be, for example, 780 or less, 760 or less, 740 or less, or 720 or less.

The glass of the present invention preferably has an average linear expansion coefficient α of 90×10 ⁻⁷ ° C. ⁻¹ or less at 100 to 300° C. In particular, the glass of the present invention has an average coefficient of linear expansion α at 100 to 300 ° C. specified in Japan Optical Glass Industry Standard JOGIS08-2003, preferably 90 × 10 ^-7 ° C. ^-1 , more preferably 88 × 10 The upper limit is ^-7 ° C. ^-1 , more preferably 86×10 ^-7 ° C. ^-1 . Although the lower limit of the average linear expansion coefficient α of the glass of the present invention is not particularly limited, the average linear expansion coefficient α of the glass of the present invention is, for example, 60×10 ⁻⁷ ° C. ⁻¹ or more, 65×10 ⁻⁷ ° C. ⁻ The lower limit may be ¹ or more and 70×10 ⁻⁷ ° C. ⁻¹ or more.

The glass of the present invention preferably has a ratio of β to α, β/α, of 7.80 or more, where β is the average coefficient of linear expansion at 100 to 300°C and the Knoop hardness. Glass has the property that even if there is a minute scratch on the surface of the glass, the scratch will grow, and when an impact is applied, the scratch will grow further and the glass will break. In order to produce a glass that is hard to break without chemical strengthening or the like, it is effective to increase the hardness of the glass and suppress scratches on the glass surface. However, the inventors have found that even if the hardness of the glass is the same, the glass does not necessarily withstand the impact of the same degree. That is, even if the hardness of the glass is about the same, by reducing the average coefficient of linear expansion α, the structure inside the glass can be strengthened and the impact to the inside of the glass can be suppressed, resulting in resistance. A glass with high impact resistance can be obtained. The glass of the present invention has an average linear expansion coefficient α at 100 to 300 ° C. and a Knoop hardness as β. You can get strong glass. β/α is preferably 7.80 or more, more preferably 7.83 or more, still more preferably 7.85 or more, still more preferably 7.88 or more, still more preferably 7.90 or more, still more preferably 7.93 or more is the lower limit. On the other hand, the upper limit of β/α is preferably 9.50 or less, more preferably 9.30 or less, and still more preferably 9.10 or less.

The lower limit of the refractive index (n _d ) of the glass of the present invention is preferably 1.80000 or more, more preferably 1.81000 or more, and still more preferably 1.82000 or more. The refractive index (n _d ) of the glass of the present invention may be preferably 1.95000 or less, more preferably 1.94000 or less, and more preferably 1.93000 or less.
The Abbe number (ν _d ) of the glass of the present invention is preferably 23.00 or more, more preferably 25.00 or more, still more preferably 28.00 or more. The Abbe number (ν _d ) is preferably 40.00 or less, more preferably 38.00 or less, and even more preferably 36.00 or less.

[Production method]
The glass of the present invention is produced, for example, as follows. That is, high-purity raw materials used in ordinary glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphoric acid compounds are used as raw materials for each of the above components, and each component is contained within a predetermined content range. The resulting mixture is put into a platinum crucible and melted in an electric furnace at a temperature range of 1000 to 1400 ° C. for 1 to 10 hours according to the melting difficulty of the glass raw materials, and stirred and homogenized. After that, it is cooled to an appropriate temperature, cast into a mold, and slowly cooled.

At this time, it is preferable to use a glass raw material with high meltability. As a result, melting at a lower temperature and melting in a shorter time are possible, so that the productivity of glass can be improved and the production cost can be reduced. In addition, volatilization of the components and reaction with the crucible and the like are reduced, so that less colored glass can be easily obtained.

[Optical glass and optical element]
A glass molded body can be produced from the produced glass by, for example, polishing means or mold press molding means such as reheat press molding or precision press molding. In addition, the means for producing the glass molded body is not limited to these means.

The glass of the present invention can be used as optical glass and is useful for various optical elements and optical designs. The glass molded body made of the glass of the present invention can be used, for example, for optical elements such as lenses, prisms, and mirrors, and is also used for applications requiring impact resistance, such as vehicle-mounted optical devices such as vehicle-mounted cameras. be able to.

Compositions of Examples 1 to 15 of the present invention and Comparative Examples 1 to 3, and refractive index (n _d ), Abbe number (ν _d ), Knoop hardness, average linear expansion coefficient at 100 to 300 ° C. of these glasses Tables 1 and 2 show the results of α. It should be noted that the following examples are for the purpose of illustration only, and the present invention is not limited only to these examples.

The glasses of the examples of the present invention use high-purity raw materials such as corresponding oxides, hydroxides, carbonates, nitrates, fluorides, metaphosphate compounds, etc., which are used in ordinary glasses, as raw materials for each component. After selecting, weighing and mixing uniformly so that the composition ratio of each example shown in the table is obtained, it is put into a platinum crucible and heated to 1000 to 1400 ° C. in an electric furnace depending on the melting difficulty of the glass raw material. After being melted for 1 to 10 hours in a temperature range, it was stirred and homogenized, cast into a mold or the like, and slowly cooled.

The refractive index (n _d ) and Abbe number (ν _d ) of the glasses of Examples and Comparative Examples were measured according to the V-block method defined in JIS B 7071-2:2018. Here, the refractive index (n _d ) is shown as a measured value for the d-line (587.56 nm) of a helium lamp. In addition, the Abbe number (ν _d ) is the refractive index (n _d ) for the d-line of the helium lamp, the refractive index (n _F ) for the F-line (486.13 nm) of the hydrogen lamp, and the C-line (656.27 nm). Using the value of the refractive index (n _C ), it was calculated from the formula of Abbe number (ν _d )=[(n _d −1)/(n _F −n _C )]. These refractive index (n _d ) and Abbe's number (ν _d ) were determined by measuring the glass obtained at a slow cooling rate of −25° C./hr.

In addition, the Knoop hardness (Hk) of the glass of Examples and Comparative Examples was measured based on the Japan Optical Glass Industry Association Standard (JOGIS09-2019). Specifically, a diamond rhombic indenter (diagonal angles of 172.5° and 130°) on the flat polished surface of the sample was pressed for 15 seconds under a load of 0.98 N (0.1 kgf) to make an indentation, and the longer diagonal of the indentation was measured and obtained by the formula (1).

Knoop hardness = 1.451 F/l ² (1)
F: Load (N)
l: length of the longer diagonal (mm)
Grade 1 if the Knoop hardness is less than 150, Grade 2 for 150 or more and less than 250, Grade 3 for 250 or more and less than 350, Grade 4 for 350 or more and less than 450, Grade 5 for 450 or more and less than 550, Grade 5 for 550 or more and less than 650 A grade of 650 or higher is defined as grade 7, and the higher the grade, the harder the glass.

In addition, the average linear expansion coefficient α of the glasses of Examples and Comparative Examples at 100 to 300 ° C. was determined according to the Japan Optical Glass Industry Standard JOGIS08-2003 "Method for measuring thermal expansion of optical glass" using a vertical expansion measuring instrument (Bruker (manufactured by the company). Here, a sample having a diameter of 4.5 mm and a length of 20 mm was used for the measurement, and the heating rate was 4° C./min.

As shown in the table, the glass of the example had a Knoop hardness of grade 6 or higher and 600 or higher.

Further, the glass of the example of the present invention had an average coefficient of linear expansion α of 90×10 ^-7 ° C. ^-1 or less at 100 to 300°C.

Further, all the glasses of Examples had a refractive index (n _d ) of 1.80000 or more and 1.95000 or less, which was within the desired range. In addition, the Abbe number (ν _d ) of the glass of the examples of the present invention was within the range of 23.00 or more and 40.00 or less.

Next, the following experiments were conducted for Examples 3 and 10 and Comparative Example 2.

A steel ball of 71.7 g (about 2.6 cm in diameter) made of SUJ2 was prepared, and on a SUS plate, a SUS ball with a diameter of 35 mm was hollowed out in the center so that the opening had a circular diameter of 30 mm. A cylindrical body is installed, and a double-sided optically polished glass with a diameter of 35 mm and a thickness of 2 mm is installed on it, and it is fixed with a SUS lid cut out so that the opening has a circular opening with a diameter of 30 mm. did. When a steel ball is allowed to fall freely in the center of the main surface of the optically double-sided polished glass with a diameter of 35 mm and a thickness of 2 mm set on the above fixing jig, at least a part of the glass cracks, chips, breaks, etc. The minimum height (cm) that is damaged by

As shown in Table 3, the glasses of Examples 3 and 10 of the present invention having β/α of 7.80 or more have higher impact resistance than the glass of Comparative Example 2 having β/α of less than 7.80. was glass. Furthermore, when the glasses of Example 3 and Example 10 were compared, the glass of Example 3, which had a larger β/α, had higher impact resistance. Therefore, it was found that glass having high impact resistance can be obtained by adjusting β/α.

Although the invention has been described in detail for purposes of illustration, the examples are for illustration only and many modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. be understood.

Claims

% by mass based on oxides,
mass sum of SiO 2 +B 2 O 3 +Al 2 O 3 +La 2 O 3 +Y 2 O 3 +Gd 2 O 3 is 50.0% or more (however, the SiO 2 component is 22.0% or less);
mass ratio Al 2 O 3 /(SiO 2 +B 2 O 3 ) is 0.01 or more;
BaO content is 10.0% or less,
and
When the average linear expansion coefficient α at 100 to 300 ° C. and the Knoop hardness are β,
A glass in which β/α, which is the ratio of β to α, is 7.80 or more.
2. The glass according to claim 1 , wherein the mass sum of Nb2O5 +WO3 is 10.0% or less.
The glass according to claim 1 or 2 , wherein the mass ratio TiO2 /( SiO2 + B2O3 + Al2O3 ) is 0.20 or more.
Mass ratio Gd 2 O 3 /Ln 2 O 3 is 0.10 or less (Ln is one or more selected from the group consisting of La, Y, Gd, and Yb)
The glass according to any one of claims 1 to 3.
Knoop hardness is grade 6 or higher,
The glass according to any one of claims 1 to 4, which has an average linear expansion coefficient α of 90 × 10 -7 °C -1 or less at 100 to 300°C.
An optical glass comprising the glass according to any one of claims 1 to 5.
An optical element made of the glass according to claim 6 .