JP2024021478A - Optical glass and optical element - Google Patents

Abstract

To provide an optical glass and an optical element having high transmittance, excellent versatility, high productivity despite a high refractive index.SOLUTION: An optical glass contains, in mol% on an oxide basis, a La2O3 component by 15.0 to 30.0%, a ZnO component by 0 to 8.0%, a BaO component by 0 to 10.0%, a sum of contents of Rn2O components (in the formula, Rn denotes one or more kinds selected from a group consisting of Li, Na, K) by more than 0% and 10.0% or less, where a molar ratio (SiO2+B2O3)/(TiO2+ZrO2+Nb2O5) is 0.80 or less, a molar ratio (SiO2+B2O3)/Ln2O3 (in the formula, Ln denotes one or more kinds selected from a group consisting of La, Y, Gd, Yb) is 1.01 or more and 2.00 or less, a molar ratio Nb2O5/(TiO2+Nb2O5+WO3+Bi2O3) is 0.10 or more.SELECTED DRAWING: None

Description

The present invention relates to optical glass and optical elements.

Optical glasses and optical elements can be used to improve the optical properties of cameras, video devices, etc. by combining lenses with different optical regions, and to be installed in optical equipment to realize various optical designs. Recently, the market for optical equipment equipped with augmented reality devices and virtual reality devices has also expanded.

In particular, optical glass with a high refractive index and good transmittance is highly versatile in use, but in order to increase the refractive index, it is necessary to use ₂ components of TiO, ₅ components of Nb ₂ O, ₃ components of WO, ₃ components of Bi ₂ O, etc. It is necessary to increase the content. However, these components are components that cause coloring of the glass due to platinum produced during the melting process of the glass.

Furthermore, from the viewpoint of stably supplying optical glass and increasing productivity, it is important that the glass has high devitrification resistance during the manufacturing process and molding.

Japanese Patent Application Publication No. 2015-040171 JP2017-88482A

The glasses disclosed in Patent Documents 1 and 2 cannot be said to have sufficient refractive index or transmittance, and cannot be said to be highly versatile glasses with high refractive index and high transmittance.

The present invention has been made in view of the above problems, and its purpose is to provide an optical glass and an optical element that have a high refractive index, high transmittance, excellent versatility, and high productivity. It's about getting.

In order to solve the above-mentioned problems, the present inventor has carried out extensive testing and research, and as a result, it has been found that the present invention contains La ₂ O ₃ components and Rn ₂ O component, suppresses the contents of ZnO component and BaO component, and improves the molar ratio (SiO ₂ +B ₂ O ₃ )/(TiO ₂ +ZrO ₂ +Nb ₂ O ₅ ), molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O _3, molar ratio Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ), it was discovered that an optical glass and an optical element having a high refractive index, high transmittance, excellent versatility, and high productivity can be obtained.
Specifically, the present invention provides the following.

(1) In mol% based on oxides,
La ₂ O ₃ components 15.0 to 30.0%,
ZnO component from 0 to 8.0%,
BaO component 0-10.0%,
The sum of the contents of Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is more than 0% and 10.0% or less,
The molar ratio (SiO ₂ +B ₂ O ₃ )/(TiO ₂ +ZrO ₂ +Nb ₂ O ₅ ) is 0.80 or less,
The molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O ₃ (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) is 1.01 or more and 2.00 or less,
An optical glass having a molar ratio Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) of 0.10 or more.

(2) The optical glass according to (1), which has a refractive index (n _d ) of 1.98000 or more.

(3) An optical element made of the optical glass according to (1) or (2).

(4) An optical device comprising the optical element according to (3).

According to the present invention, it is possible to provide an optical glass and an optical element that have a high refractive index, high transmittance, excellent versatility, and high productivity.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention. Note that the description may be omitted as appropriate for parts where the description overlaps, but this does not limit the gist of the invention.

[Glass component]
The composition range of each component constituting the optical glass of the present invention will be described below. Unless otherwise specified in this specification, the content of each component shall be expressed in mol % based on the total number of moles of glass in terms of oxide composition. Here, "composition in terms of oxide" is based on the assumption that the oxides, complex salts, metal fluorides, etc. used as raw materials for the glass components of the present invention are all decomposed and converted to oxides during melting. The composition shows each component contained in the glass, with the total number of moles of the generated oxide being 100 mol%.

The La ₂ O ₃ component is a component that is less likely to cause glass coloring than other high refractive index components and can increase the refractive index, but if the content is too large, it impairs stability and causes an increase in specific gravity. be. Therefore, the lower limit of the content of the _three La ₂ O components is preferably 15.0% or more, more preferably 16.0% or more, and even more preferably 17.0% or more. On the other hand, the upper limit of the content of the _three La ₂ O components is preferably 30.0% or less, more preferably 29.0% or less, and even more preferably 28.0% or less.

The Y ₂ O ₃ component is a component that increases the refractive index of glass, and is a component with a small specific gravity among rare earth oxides, but if the content is large, stability will be impaired. Therefore, the lower limit of the content of the _three Y ₂ O components is preferably more than 0%, more preferably 0.5% or more, and still more preferably 1.0% or more. On the other hand, the upper limit of the content of the _{three Y2O} components is preferably 10.0% or less, more preferably 8.0% or less, and still more preferably 5.0% or less.

The SiO ₂ component is a component that enhances the devitrification resistance of the glass while promoting stable glass formation, but if the content is large, the refractive index will decrease. Therefore, the content of the _two SiO2 components is preferably 30.0% or less, more preferably 28.0% or less, even more preferably 25.0% or less, even more preferably 23.0% or less, still more preferably 20.0% or less. The upper limit is 0% or less. On the other hand, the content of _{the two} SiO components may be 0%, but is preferably more than 0%, more preferably 1.0% or more, even more preferably 2.0% or more, even more preferably 3.0% or more, and The lower limit is preferably 4.0% or more, more preferably 5.0% or more.

The B ₂ O ₃ component is a component that improves devitrification resistance by promoting the formation of stable glass, and can improve stability by containing it together with the La ₂ O ₃ component. Therefore, the content of the _three B ₂ O components is preferably 40.0% or less, more preferably 38.0% or less, even more preferably 35.0% or less, even more preferably 33.0% or less, even more preferably The upper limit is 32.0% or less, more preferably 30.0% or less. On the other hand, the content of _{the three} B ₂ O components is preferably more than 0%, more preferably 1.0% or more, even more preferably 3.0% or more, even more preferably 5.0% or more, and still more preferably 6.0% or more. The lower limit is 0% or more, more preferably 8.0% or more.

The TiO ₂ component is a component that increases the refractive index and Abbe number of glass, but if it is contained in excess, it is a component that causes coloring of the glass. Therefore, the upper limit of the content of _{the two} TiO components is preferably 55.0% or less, more preferably 53.0% or less, even more preferably 50.0% or less, and still more preferably 48.0% or less. On the other hand, the content of _{the two} TiO components is preferably more than 0%, more preferably 3.0% or more, even more preferably 5.0% or more, even more preferably 8.0% or more, and even more preferably 10.0%. The lower limit is more preferably 15.0% or more, still more preferably 18.0% or more, even more preferably 20.0% or more.

The Nb ₂ O ₅ component is a component that can increase the refractive index and Abbe number of the glass, and its stability can be improved by containing it together with the TiO ₂ component, but if it is included in excess, the specific gravity will increase. Therefore, the content of the Nb ₂ O ₅ component is preferably 18.0% or less, more preferably 15.0% or less, more preferably 12.0% or less, more preferably 10.0% or less, and most preferably The upper limit is 9.0% or less. On the other hand, the lower limit of the content of the _five Nb ₂ O components is preferably 1.0% or more, more preferably 2.0% or more, and even more preferably 3.0% or more, from the viewpoint of increasing stability. , 0%.

The WO ₃ component and the Bi ₂ O ₃ component are components that increase the refractive index of the glass when contained in an amount exceeding 0%, but if the content is too large, the glass becomes colored and the specific gravity increases. The preferred ranges of the _three WO components and _{the three} Bi ₂ O components are as follows.

The upper limit of the content of the _three WO components is preferably 10.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less.

The content of the _three Bi ₂ O components is preferably 3.0% or less, more preferably 1.0% or less, even more preferably 0.8% or less, even more preferably 0.5% or less, and even more preferably 0. The upper limit is 3% or less, most preferably 0.1% or less.

The _ZrO2 component is a component that can increase the transmittance while increasing the refractive index, but if it is contained in excess, it deteriorates the workability of glass by polishing, grinding, etc. Therefore, the upper limit of the content of the _two ZrO components is preferably 10.0% or less, more preferably 9.0% or less, and even more preferably 8.5% or less. On the other hand, the lower limit of the content of the _two ZrO components is preferably more than 0%, more preferably 1.0% or more, even more preferably 2.0% or more, even more preferably 3.0% or more, but 0 It may be %.

The Li ₂ O component, K ₂ O component, and Na ₂ O component are components that lower the melting temperature of glass, but if their content is too large, they impair stability and tend to devitrify. Among the Li ₂ O component, K ₂ O component, and Na ₂ O component, the Li ₂ O component is the component that most enhances the stability of the glass when contained together with the _three La ₂ O components. The preferred ranges of the Li ₂ O component, K ₂ O component, and Na ₂ O component are as follows.

The content of the Li ₂ O component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and even more preferably 1.0%. % or less, more preferably 0.8% or less. On the other hand, the content of the Li ₂ O component is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, and still more preferably 0. The lower limit is 4% or more, but it may be 0%.

The content of the K ₂ O component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and even more preferably 1.0%. % or less, more preferably 0.8% or less. On the other hand, the content of the K ₂ O component is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, and even more preferably 0. The lower limit is 4% or more, but it may be 0%.

The content of the Na ₂ O component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and even more preferably 1.0%. % or less, more preferably 0.8% or less. On the other hand, the content of the Na ₂ O component is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, and even more preferably 0. The lower limit is 4% or more, but it may be 0%.

The BaO component is a component that increases the stability of the glass, but it is preferable to reduce its content in order to maintain the refractive index and Abbe number, and to obtain a highly versatile optical glass because of its large specific gravity. It is also preferable to reduce the content in order to maintain acid resistance. Therefore, the content of the BaO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, and still more preferably 5.0% or less. % or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less.

The CaO component, MgO component, and SrO component are components that improve the devitrification resistance of glass, but if their content is large, it becomes difficult to maintain the refractive index and Abbe number. The preferred ranges of the CaO component, MgO component, and SrO component are as follows.

The content of the CaO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, even more preferably 5.0% or less. The upper limit is more preferably 4.0% or less, further preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less.

The content of the MgO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, even more preferably 5.0% or less. The upper limit is more preferably 4.0% or less, further preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less.

The content of the SrO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, even more preferably 5.0% or less. The upper limit is more preferably 4.0% or less, further preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less.

The Gd ₂ O ₃ component and the Yb ₂ O ₃ component are components that increase the refractive index of glass, but if their content is too large, the stability will be impaired and the specific gravity will become large. The preferred ranges of the _three Gd ₂ O components and the _three Yb ₂ O components are as follows.

The content of the _three Gd ₂ O components is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably 0.0% or less. The upper limit is 5% or less.

The content of _{the three} Yb ₂ O components is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably 0. The upper limit is 5% or less.

The Al ₂ O ₃ component is a component that increases the viscosity when the glass is melted while improving the chemical durability of the glass. In particular, by controlling the content of the _three Al ₂ O components to 5.0% or less, the meltability of the glass can be increased and the tendency of the glass to devitrify can be weakened. Therefore, the upper limit of the content of the _three Al ₂ O components is preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less, but it may be 0%. .

The ZnO component is a component that lowers the liquidus temperature of the glass and increases the devitrification resistance of the glass, but if the content is large, it becomes difficult to maintain the refractive index and Abbe number. It is also preferable to reduce the content in order to maintain acid resistance. Therefore, the content of the ZnO component is preferably 8.0% or less, more preferably 7.0% or less, even more preferably 6.0% or less, even more preferably 5.0% or less, and still more preferably 4.0% or less. % or less, more preferably 3.0% or less, further preferably 2.0% or less, still more preferably 1.0% or less, but it may be 0%.

The Ta ₂ O ₅ component is a component that can increase the refractive index of the glass and improve the devitrification resistance of the glass. On the other hand, by reducing the content of Ta ₂ O ₅ components to 5.0% or less, the amount of Ta ₂ O ₅ components used, which is a rare mineral resource, is reduced, and the glass becomes easier to melt at lower temperatures. Glass production costs can be reduced. Moreover, this can reduce devitrification of the glass due to excessive inclusion of the Ta ₂ O ₅ component. Therefore, the content of _{the five} Ta ₂ O components is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less, but may be 0%. .

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, even more preferably 0.5% or less, It may be set to 0%.

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

The content of the _two TeO components is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, but the upper limit is 0%. You can also use it as

The upper limit of the content of the _three Ga ₂ O components is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, It may be set to 0%.

The content of the GeO _two components is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, but the upper limit is 0%. You can also use it as

The content of the CeO _two components is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, but the upper limit is 0%. You can also use it as

The content of Er ₂ O ₃ components and Pr ₂ O ₃ components is preferably 1.0% or less, more preferably 0.5% or less, more preferably 0.1% or less, and most preferably substantially not contained. .

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

The Sb ₂ O ₃ component is a component that promotes clarification and defoaming when melting glass, and is an optional component. Here, by setting the content of the Sb ₂ O ₃ component to 0.1% or less, it becomes possible to suppress coloring, especially in high refractive index glass. In addition, by setting the content to 0.1% or less, excessive foaming is less likely to occur during glass melting, thereby making it difficult for the Sb ₂ O ₃ component to alloy with melting equipment (particularly noble metals such as Pt). Therefore, the upper limit of the content of the _three Sb ₂ O components is preferably 0.1% or less, more preferably 0.08% or less, even more preferably 0.05% or less, but it may be 0%.

Note that the component for clarifying and defoaming the glass is not limited to the above-mentioned _three Sb ₂ O components, and a known clarifying agent, defoaming agent, or a combination thereof in the field of glass manufacturing can be used.

Component C is a component that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve transmittance. However, if the content is high, the cation components in the glass It is reduced and the glass becomes colored. Therefore, the upper limit of the content of component C is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. On the other hand, the content of the C component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, most preferably 2.0% or more, but the lower limit is 0%. But that's fine.

The S component is a component that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve transmittance, but if the content is high, the cation components in the glass It is reduced and the glass becomes colored. Therefore, the upper limit of the content of the S component is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. On the other hand, the content of the S component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, most preferably 2.0% or more, but the lower limit is 0%. But that's fine.

Organic components such as sucrose are components that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve transmittance. The cationic components are reduced and the glass becomes colored. Therefore, the upper limit of the content of organic components such as sucrose is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. . On the other hand, the lower limit of the content of organic substances such as sucrose is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more. , may be 0%.

Note that the component that reduces glass is not limited to the above-mentioned C component, S component, organic components such as sucrose, and any known reducing agent in the field of glass manufacturing or a combination thereof can be used.

The sum of the contents (molar sum) of the _three Ln ₂ O components (in the formula, Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) can increase the refractive index of the glass. If it is contained in excess, it will increase the devitrification property of the glass. Therefore, the lower limit of the sum of the contents of the _three Ln ₂ O components is preferably 15.0% or more, more preferably 18.0% or more, and still more preferably 19.0% or more. On the other hand, the sum of the contents of the _three Ln ₂ O components is preferably 40.0% or less, more preferably 35.0% or less, even more preferably 33.0% or less, even more preferably 30.0% or less. Upper limit.

The sum of the contents (mole sum) of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is a component that can improve the meltability of glass, but in excess If it is contained in the above, the devitrification resistance during processing will be deteriorated. By increasing the meltability of glass, it is possible to obtain glass with good productivity. Therefore, the sum of the contents of Rn ₂ O components is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and even more preferably The upper limit is 1.0% or less, more preferably 0.8% or less. On the other hand, the sum of the contents of Rn ₂ O components is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, and even more preferably The lower limit is 0.4% or more.

The sum of the contents (molar sum) of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is a component that increases the stability of the glass, but if This is a component that causes a decrease in the refractive index when contained. Therefore, the sum of the contents of the RO components is 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, even more preferably 6.0% or less, and still more preferably 5.0% or less. % or less, more preferably 4.0% or less, further preferably 3.0% or less, still more preferably 2.0% or less, still more preferably 1.0% or less.

_Molar ratio ( _{SiO 2 + B 2} O _{3 )} /( _{TiO 2 +} ZrO _{2 + Nb 2} O ₅ ) is 0.80 or less, a desired refractive index can be obtained while suppressing an increase in specific gravity. Therefore, the upper limit of the molar ratio (SiO ₂ +B ₂ O ₃ )/(TiO ₂ +ZrO ₂ +Nb ₂ O ₅ ) is preferably 0.80 or less, more preferably 0.79 or less, and even more preferably 0.78 or less. do. On the other hand, the molar ratio (SiO ₂ +B ₂ O ₃ )/(TiO ₂ +ZrO ₂ +Nb ₂ O ₅ ) is preferably greater than 0, more preferably 0.10 or more, still more preferably 0.15 or more, and even more preferably The lower limit is 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more.

The molar ratio (SiO ₂ +B ₂ O ₃ )/Ln 2 O ₃ , _{which is} the total content of SiO ₂ components and B ₂ O ₃ components with respect to the total content of Ln ₂ O 3 components, is set to 1.01 or more. , deterioration of devitrification resistance can be suppressed. Therefore, the molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O ₃ is preferably 1.01 or more, more preferably 1.02 or more, still more preferably 1.03 or more, even more preferably 1.04 or more. Set as the lower limit. On the other hand, by setting the molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O ₃ to 2.00 or less, the transmittance can be increased while obtaining the desired refractive index. Therefore, the molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O ₃ is preferably 2.00 or less, more preferably 1.95 or less, still more preferably 1.90 or less, even more preferably 1.85 or less. Upper limit.

Molar ratio of Nb ₂ O ₅ components to the total content of TiO ₂ components, Nb ₂ O ₅ components, WO ₃ components, and Bi ₂ O ₃ components Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) is 0.10 or more, the refractive index can be increased. The Nb ₂ O ₅ component is the component that increases the refractive index most among the high refractive index components of the TiO ₂ component, the WO ₃ component, and the Bi ₂ O ₃ component. By adjusting the total amount of high refractive index components and the content of Nb ₂ O ₅ components, it is possible to increase the refractive index while suppressing coloring of the glass. Therefore, the lower limit of the molar ratio Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) is preferably 0.10 or more, more preferably 0.11 or more, and even more preferably 0.12 or more. . On the other hand, the molar ratio Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) is preferably 0.30 or less, more preferably 0, from the viewpoint of suppressing devitrification and coloring due to excessive content. It may be .25 or less, more preferably 0.23 or less.

By setting the molar ratio _{Y 2} O _{3 /} Ln 2 O ₃ of the three Y _{2 O} components to the total content of the three Ln ₂ O components to be 0.05 or more, the specific gravity of the glass can be reduced. The Y ₂ O ₃ component has a lower specific gravity than other rare earth oxides, so by adjusting the ratio of the rare earth oxide and the Y ₂ O ₃ component, it is possible to increase the refractive index while suppressing coloring. You can also get Therefore, the lower limit of the molar ratio Y ₂ O ₃ /Ln ₂ O ₃ is preferably 0.05 or more, more preferably 0.07 or more, even more preferably 0.10 or more, and still more preferably 0.13 or more.

<About ingredients that should not be included>
Next, components that should not be included in the optical glass of the present invention and components that are not preferably included will be explained.

Other components may 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 these substances is contained singly or in combination, the glass will be colored and have the property of absorbing specific wavelengths in the visible range. is preferred.

Further, 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 substantially not contained, that is, not contained at all except for unavoidable contamination.

Furthermore, the use of Th, Cd, Tl, Os, Be, and Se as harmful chemical substances has tended to be avoided in recent years, and they are used not only in the glass manufacturing process but also in the processing process and disposal after product production. Environmental measures are required throughout. Therefore, when placing importance on the environmental impact, it is preferable not to substantially contain these.

[Physical properties]
The lower limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.98000 or more, more preferably 1.99000 or more, and even more preferably 2.00000 or more. On the other hand, this refractive index (n _d ) may be preferably 2.50000 or less, more preferably 2.30000 or less, still more preferably 2.20000 or less, still more preferably 2.10000 or less. The lower limit of the Abbe number (v _d ) of the present invention is preferably 18.00 or more, more preferably 20.00 or more, and still more preferably 23.00 or more. On the other hand, the upper limit of this Abbe number (v _d ) is preferably less than 35.00, more preferably 33.00 or less, and even more preferably 30.00 or less.

Moreover, it is preferable that the glass of the present invention has little coloring. In particular, the glass of the present invention has a wavelength (λ ₇₀ ) at which the spectral transmittance is 70% in a 10 mm thick sample, which is preferably 480 nm or less, more preferably 470 nm or less, and still more preferably 460 nm. Hereinafter, the upper limit is more preferably 450 nm or less. Further, the wavelength (λ ₅ ) exhibiting spectral transmittance of 5% is preferably 390 nm or less, more preferably 385 nm or less, and still more preferably has an upper limit of 380 nm or less.

Optical glass with a high refractive index and good transmittance can be used in a variety of applications such as cameras, video equipment, and optical equipment equipped with augmented reality devices and virtual reality devices, so the optical glass of the present invention is versatile. is high.

The specific gravity (d) of the optical glass of the present invention is preferably in the order of 5.50 or less, 5.40 or less, 5.30 or less, 5.20 or less, and 5.10 or less.
By reducing the specific gravity, the glass becomes lighter, making it possible to reduce the weight of optical equipment.

The upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1250°C or lower, more preferably 1230°C or lower, even more preferably 1210°C or lower.
By lowering the liquidus temperature, a glass with excellent stability and good productivity can be obtained.

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are mixed uniformly so that each component is within a predetermined content range, the prepared mixture is put into a platinum crucible, and heated at 1100 to 1500°C in an electric furnace depending on the difficulty of melting the glass raw material. It is produced by melting for 2 to 5 hours at a temperature range of 2 to 5 hours to homogenize by stirring, then lowering the temperature to an appropriate temperature, casting into a mold, and slowly cooling. A reducing agent or defoaming agent may be appropriately used together with the glass raw material.

[Glass molding]
The glass of the present invention can be melt-molded by a known method. Note that the means for molding the glass melt is not limited.

[Optical element]
A glass molded body can be produced from the produced optical glass using, for example, a polishing method or a mold press forming method such as reheat press molding or precision press molding. That is, a glass molded body can be produced by performing mechanical processing such as grinding and polishing on optical glass. Note that the means for producing the glass molded body are not limited to these means.

As described above, the optical glass of the present invention is useful for various optical elements and optical designs, and can realize high-definition and high-precision imaging characteristics and projection characteristics when used in optical devices such as cameras and projectors. . Further, by using it in a light guide plate that is a component of an image display device such as augmented reality (AR), virtual reality (VR), or mixed reality (MR), a wide viewing angle and high brightness can be realized.

Compositions of Examples and Comparative Examples of glasses of the present invention, refractive index (n _d ), Abbe number (ν _d ), and wavelengths (λ ₅ , λ ₇₀ ), specific gravity (d), and liquidus temperature are shown in Table 1.

The optical glass of the present invention is made of high-purity materials such as oxides, hydroxides, carbonates, nitrates, sulfates, fluorides, metaphosphoric acid compounds, etc. that are used as raw materials for ordinary optical glasses. After selecting the raw materials, weighing them so as to have the composition ratio of each example shown in the table, and mixing them uniformly, they are placed in a platinum crucible, and heated to 1100 to 1000 in an electric furnace depending on the difficulty of melting the glass raw materials. It is produced by melting at a temperature range of 1500°C for 30 minutes to 2 hours, stirring to homogenize, casting into a mold, etc., and slowly cooling.

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 specified in JIS B 7071-2:2018. Here, the refractive index (n _d ) is shown as a value measured with respect to 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 a helium lamp, the refractive index (n _F ) for the F-line (486.13 nm) of a hydrogen lamp, and the refractive index for the C-line (656.27 nm) of a hydrogen lamp. The value of the refractive index (n _C ) was used to calculate the Abbe number (ν _d )=[(n _d −1)/(n _F −n _C )]. These refractive index (n _d ) and Abbe number (ν _d ) were determined by measuring the glass obtained by setting the slow cooling temperature drop rate to −25° C./hr.

The transmittance of the glasses of Examples and Comparative Examples was measured in accordance with the Japan Optical Glass Industry Association standards (JOGIS02-2019 Method for Measuring Coloring Degree of Optical Glass). In the present invention, the presence or absence and degree of coloring of the glass was determined by measuring the transmittance of the glass. Specifically, the spectral transmittance of 200 to 700 nm was measured for a parallel-polished product with a thickness of 10±0.1 mm in accordance with JIS Z8722, and λ ₇₀ (wavelength at 70% transmittance) and λ ₅ (transmittance) were measured. (wavelength at 5%) was determined.

The specific gravity in the glass in the examples was determined based on the method for measuring density and specific gravity using the submerged weighing method of JIS Z8807:2012.

The liquidus temperature of the glass in the example was determined by placing a 5 cc cullet-shaped glass sample in a platinum crucible with a capacity of 50 ml, bringing it to a completely molten state at 1400°C, lowering the temperature to a predetermined temperature, and holding it for 1 hour. This is the lowest temperature at which no crystals are observed when observing the presence or absence of crystals on the glass surface and in the glass immediately after it has been taken out of the furnace and cooled. The predetermined temperature at which the temperature is lowered is a temperature between 1350°C and 800°C in 10°C increments.

As shown in the table, all the glasses of Examples of the present invention had a refractive index (n _d ) of 1.98000 or more, more specifically 2.00000 or more, which was within the desired range.

The glasses of the examples of the present invention all have an Abbe number (ν _d ) of 20.00 or more, more specifically 23.00 or more, and this Abbe number (ν _d ) is 35.00 or less, more specifically was 30.00 or less, which was within the desired range.

The glasses of the examples of the present invention all have a wavelength (λ ₇₀ ) of 480 nm or less, more specifically 460 nm or less, and a wavelength (λ ₅ ) of 390 nm or less, more specifically 380 nm or less, and have a desired wavelength (λ 5 ) of 390 nm or less, more specifically 380 nm or less. It was within the range.
On the other hand, it could not be said that Comparative Example 1, which did not satisfy the claims, had sufficient refractive index and transmittance.

The glasses of Examples of the present invention all had a specific gravity (d) of 5.50 or less, more specifically 5.10 or less, which was within the desired range.

The glasses of Examples of the present invention were all highly stable glasses.

Therefore, it has been revealed that the optical glass of the example of the present invention has a high refractive index, a high transmittance, and a high stability.

Although the present invention has been described in detail above for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. will be understood.

Claims (4)

In mole% based on oxides,
La ₂ O ₃ components 15.0 to 30.0%,
ZnO component from 0 to 8.0%,
BaO component 0-10.0%,
The sum of the contents of Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is more than 0% and 10.0% or less,

The molar ratio (SiO ₂ +B ₂ O ₃ )/(TiO ₂ +ZrO ₂ +Nb ₂ O ₅ ) is 0.80 or less,
The molar ratio (SiO ₂ +B ₂ O ₃ )/Ln ₂ O ₃ (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) is 1.01 or more and 2.00 or less,
An optical glass having a molar ratio Nb ₂ O ₅ /(TiO ₂ +Nb ₂ O ₅ +WO ₃ +Bi ₂ O ₃ ) of 0.10 or more. The optical glass according to claim 1, having a refractive index (n _d ) of 1.98000 or more. An optical element comprising the optical glass according to claim 1 or 2. An optical device comprising the optical element according to claim 3.