TW201815705A - Optical glass, preform material, and optical element - Google Patents

Abstract

Provided are: an optical glass that has good chemical durability, a small specific gravity, and optical characteristics including a medium refractive index and low dispersion; and a preform material and an optical element using the optical glass. In terms of mol%, the molar sum of (SiO2+B2O3) in the optical glass is 40.0-75.0%, the molar sum of a Ln2O3 component (in the formula, Ln is one or more substances selected from the group consisting of La, Gd, Y, and Lu) is 3.0-25.0%, and the molar sum of an Rn2O component (in the formula, Rn is one or more substances selected from the group consisting of Li, Na, and K) is more than 0% but no more than 25.0%. The value of d×RA obtained by multiplying the specific gravity (d) of the glass and the acid resistance class (RA) by powder method is 15.0 or less. The optical glass has a refractive index (nd) of 1.58-1.80 and an Abbe number ([nu]d) of 35-65.

Description

   Optical glass, preforms and optical elements   

The invention relates to an optical glass, a preform and an optical element.

In recent years, the digitization or high-definition of equipment using optical systems is rapidly developing. In various optical equipment fields, such as digital cameras or video cameras, imaging equipment such as projectors, and image reproduction (projection) equipment such as projection televisions, optical reduction is required. The number of lenses or optical elements used in the system has increased the demand for lighter and smaller overall optical systems.

In the production of optical glass for optical elements, in particular, among optical glasses that can achieve weight reduction and miniaturization of the entire optical system or correction of chromatic aberration, which have a refractive index of 1.60 or more and an Abbe number of 35 or more and 65 or less, v d The demand for low refractive index dispersion glasses is very high.

As such a medium-refractive-index low-dispersion glass, the glass composition typified by patent document 1-patent document 2 is known. However, most of these glass compositions composed of B ₂ O ₃ -La ₂ O ₃ systems are susceptible to water or acids in terms of characteristics of glass components generally used, and have insufficient durability. Therefore, when the glass is polished, the glass may be deteriorated and a defect may be caused in the manufacturing process.

In addition, in recent years, surveillance cameras, in-vehicle cameras, and the like, which have been expanding in demand, are often used outdoors, and are therefore often exposed to wind and rain, or water vapor in the atmosphere. When using a conventional photographic element using a glass composition, the long-term use outside is assumed, and the glass compositions described in Patent Documents 1 to 2 have insufficient durability.

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 55-080736.

Patent Document 2: Japanese Patent Application Laid-Open No. 11-139844.

This invention was created in view of the said subject. The objective of this invention is to obtain the optical glass which has the optical constant of the said predetermined range, favorable chemical durability, and small specific gravity.

The inventors of the present invention conducted intensive experimental research to solve the above-mentioned problems, and as a result, found that a glass having a specific composition was obtained to solve the above-mentioned problems until the present invention was completed. Specifically, the present invention provides the following technical solutions.

(1) An optical glass, in Mohr%, containing: Mohr and (SiO ₂ + B ₂ O ₃ ) 40.0 to 75.0%; Ln ₂ O ₃ component (wherein, Ln is selected from La, Gd, The Mohr sum of one or more of the group consisting of Y and Lu is 3.0% to 25.0%; the Rn ₂ O component (wherein, Rn is one or more members selected from the group consisting of Li, Na, and K) The molar sum is more than 0% to 25.0%; the multiplication of the glass specific gravity (d) and the powder method acid resistance level (RA) d × RA value is 15.0 or less, and the optical glass has a refractive index of 1.58 or more and 1.80 or less ( nd) and has an Abbe number ( v d) of 35 to 65.

(2) The optical glass according to (1), which, in molar%, contains: SiO ₂ component 5.0% to 60.0%, B ₂ O ₃ component 0% to 70.0%, and Al ₂ O ₃ component 0% to 25.0%, La ₂ O ₃ component 0% to 25.0%, Y ₂ O ₃ component 0% to 25.0%, Gd ₂ O ₃ component 0% to 25.0%, Lu ₂ O ₃ component 0% to 5.0%, Yb ₂ O ₃ components 0% to 5.0%, ZrO ₂ components 0% to 10.0%, TiO ₂ components 0% to 10.0%, Nb ₂ O ₅ components 0% to 10.0%, Ta ₂ O ₅ components 0% to 5.0%, WO ₃ Component 0% to 5.0%, ZnO component 0% to 30.0%, MgO component 0% to 30.0%, CaO component 0% to 35.0%, SrO component 0% to 30.0%, BaO component 0% to 30.0%, Li ₂ O Component 0% to 20.0%, Na ₂ O component 0% to 15.0%, K ₂ O component 0% to 15.0%, GeO ₂ component 0% to 10.0%, Ga ₂ O ₃ component 0% to 10.0%, P ₂ O ₅ components 0% to 10.0%, Bi ₂ O ₃ component 0% to 5.0%, TeO ₂ component 0% to 5.0%, SnO ₂ component 0% to 3.0%, and Sb ₂ O ₃ component 0% to 1.0%.

(3) The optical glass according to any one of (1) or (2), wherein the molar ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ is 0.1 or more.

(4) The optical glass according to any one of (1) to (3), wherein Mohr and (SiO ₂ + Al ₂ O ₃ ) are 8.0% to 65.0%.

(5) The optical glass according to any one of (1) to (4), wherein the molar ratio (Ln ₂ O ₃ / Rn ₂ O) is 0.3 or more.

(6) The optical glass according to any one of (1) to (5), wherein Mohr and (ZrO ₂ + TiO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ + Bi ₂ O ₃ + TeO ₂ ) is 0% to 20.0%.

(7) The optical glass according to any one of (1) to (6), wherein the molar ratio (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) 0.2 to 3.0.

(8) The optical glass according to any one of (1) to (7), wherein the molar product (BaO × Gd ₂ O ₃ ) is less than 5.0%.

(9) The optical glass according to any one of (1) to (8), wherein the chemical durability (acid resistance) measured by a powder method has a grade of 1 to 4.

(10) The optical glass according to any one of (1) to (9), wherein the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) The Mohr sum is below 40.0%.

(11) A preform made of the optical glass according to any one of (1) to (10).

(12) An optical element composed of the optical glass according to any one of (1) to (10).

(13) An optical device including the optical element according to (12).

According to the present invention, a glass having a predetermined range of optical constants and good chemical durability can be obtained.

Hereinafter, embodiments of the glass of the present invention will be described in detail. However, the present invention is not limited in any way by the following embodiments, and may be appropriately modified and implemented within the scope of the object of the present invention. In addition, the description of overlapping portions may be omitted as appropriate, but the gist of the invention is not limited.

[Glass composition]

Hereinafter, the composition range of each component constituting the optical glass of the present invention will be described. In this specification, unless otherwise specified, the content of each component is expressed in terms of mole% of the total oxide conversion composition relative to the total glass content. Here, the "oxide conversion composition" is based on the assumption that all oxides, composite salts, metal fluorides, and the like used as raw materials for the glass constituents of the present invention are decomposed during melting to become oxides. Molar% of the converted composition relative to the total mole number is expressed.

When Moire (SiO ₂ + B ₂ O ₃ ) is 40.0% or more, the effect of improving devitrification resistance is easily obtained.

Thus, the Mohr and lower limit of (SiO ₂ + B ₂ O ₃ ) is preferably 40.0%, more preferably 45.0%, and still more preferably 50.0%.

On the other hand, by making the Mohr sum to 75.0% or less, it is possible to suppress deterioration of the meltability of the glass raw material or excessive increase in viscosity. Therefore, the molar sum of (SiO ₂ + B ₂ O ₃ ) is preferably 75.0%, more preferably 70.0%, and still more preferably 65.0%.

The sum (molar sum) of the content of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Lu) is preferably 3.0% or more and 25.0% or less.

In particular, by making the sum 3.0% or more, the refractive index and Abbe number of the glass are improved, and therefore, a glass having a desired refractive index and Abbe number can be easily obtained. Therefore, the Mohr and lower limit of the Ln ₂ O ₃ component is preferably 3.0%, more preferably 6.0%, still more preferably 8.0%, and most preferably 10%.

On the other hand, when the sum is 25.0% or less, the liquidus temperature of the glass is reduced, and therefore, devitrification of the glass can be reduced. Therefore, the Mohr sum of the Ln ₂ O ₃ component is preferably 25.0%, more preferably 20.0%, and even more preferably 18.0%.

The sum (molar sum) of the content of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 25.0% or less. Thereby, deterioration of chemical durability due to excessive content is suppressed. Therefore, the upper limit of the total content is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, still more preferably 10.0%, still more preferably 5.0%, and most preferably 3.0%.

On the other hand, by making this sum 0% or more, deterioration of the meltability or excessive increase in viscosity is suppressed. Therefore, the Mohr and lower limit of the Rn ₂ O component is preferably greater than 0%, more preferably 0.5%, and still more preferably 1.0%.

The SiO ₂ component is an essential component for improving devitrification resistance or chemical durability. The lower limit of the content of the SiO ₂ component is preferably 5.0%, more preferably 10.0%, and still more preferably 15.0%.

On the other hand, when the content of the SiO ₂ component is 60.0% or less, a larger refractive index can be easily obtained, and deterioration in meltability or excessive increase in viscosity can be suppressed. Therefore, the upper limit of the content of the SiO ₂ component is preferably 60.0% or less, more preferably 50.0%, still more preferably 40.0%, still more preferably 30.0%, and most preferably 20.0%.

As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

The B ₂ O ₃ component is an arbitrary component having an effect of improving meltability and improving devitrification resistance. The content of the B ₂ O ₃ component is preferably greater than 0%, the lower limit is more preferably 5.0%, still more preferably 10.0%, still more preferably 15.0%, even more preferably 20.0%, even more preferably 30.0%, and most preferably 40.0%.

On the other hand, when the content of the B ₂ O ₃ component is 70.0% or less, the deterioration of the glass durability is suppressed. Therefore, the upper limit of the content of the B ₂ O ₃ component is preferably 70.0%, more preferably 60.0%, still more preferably 55.0%, and most preferably 50.0%.

As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ ‧ 10H ₂ O, BPO ₄ and the like can be used as raw materials.

The Al ₂ O ₃ component is an arbitrary component having an effect of improving devitrification resistance or chemical durability. The content of the Al ₂ O ₃ component is preferably greater than 0%, the lower limit is more preferably 0.5%, and still more preferably 1.0%.

In particular, when the content of the Al ₂ O ₃ component is 5.0% or more, when a large amount of the Rn ₂ O component is contained, chemical durability can be significantly improved. Therefore, the lower limit of the content of the Al ₂ O ₃ component is preferably 5.0%, more preferably 10.0%, and most preferably 15.0%.

On the other hand, when the content of the Al ₂ O ₃ component is 25.0% or less, deterioration in devitrification resistance or reduction in refractive index due to excessive content is suppressed. Therefore, the upper limit of the content of the Al ₂ O ₃ component is preferably 25.0%, more preferably 20.0%, and most preferably 18.0%.

As the Al ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Al (PO ₃ ) ₃ or the like can be used as a raw material.

The La ₂ O ₃ component is an arbitrary component that increases the refractive index of glass and increases the Abbe number of glass. Therefore, the content of the La ₂ O ₃ component is preferably greater than 0%, the lower limit is more preferably 1.0%, further more preferably 3.0%, still more preferably 5.0%, and most preferably 8.0%.

On the other hand, when the content of the La ₂ O ₃ component is 25.0% or less, the stability of the glass is improved, and thereby devitrification can be reduced. Therefore, the upper limit of the content of the La ₂ O ₃ component is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, and most preferably 12.0%.

As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ ‧XH ₂ O (X is an arbitrary integer), or the like can be used as a raw material.

The Y ₂ O ₃ component is an arbitrary component that maintains a high refractive index and a high Abbe number while maintaining a high refractive index and a high Abbe number while suppressing the material cost of the glass, and can reduce the specific gravity of the glass compared to other rare earth components. Therefore, the content of the Y ₂ O ₃ component is preferably greater than 0%, the lower limit is more preferably 1.0%, still more preferably 2.5%, and most preferably 3.5%.

On the other hand, when the content of the Y ₂ O ₃ component is 25.0% or less, the devitrification resistance of the glass is improved. Therefore, the upper limit of the content of the Y ₂ O ₃ component is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, even more preferably 10.0%, and most preferably 5.0%.

As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

When the Gd ₂ O ₃ component is contained at more than 0%, it is an arbitrary component that increases the refractive index of glass and increases the Abbe number.

On the other hand, by setting the expensive Gd ₂ O ₃ component to 25.0% or less, the increase in specific gravity is suppressed, and the material cost of glass is reduced. Therefore, optical glass can be produced more inexpensively. Therefore, the upper limit of the content of the Gd ₂ O ₃ component is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, still more preferably 10.0%, even more preferably 5.0%, and most preferably 1.0%. From the viewpoint of suppressing a reduction in material cost or an increase in specific gravity, the Gd ₂ O ₃ component may not be contained.

As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF _3, or the like can be used as a raw material.

When the Lu ₂ O ₃ component is contained at more than 0%, it is an arbitrary component that increases the refractive index of glass and increases the Abbe number.

On the other hand, since the content of the Lu ₂ O ₃ component is 5.0% or less, the material cost of the glass is reduced, and therefore, optical glass can be produced more inexpensively. In addition, by this, the devitrification resistance of the glass is improved. Therefore, the upper limit of the content of the Lu ₂ O ₃ component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%. From the viewpoint of reducing the material cost, the Lu ₂ O ₃ component may not be contained.

As the Lu ₂ O ₃ component, Lu ₂ O ₃ or the like can be used as a raw material.

When the Yb ₂ O ₃ component is contained at more than 0%, it is an arbitrary component that increases the refractive index of glass and increases the Abbe number.

On the other hand, since the content of the Yb ₂ O ₃ component is 5.0% or less, the material cost of the glass is reduced, and therefore, optical glass can be produced more inexpensively. In addition, this improves the devitrification resistance of the glass. Therefore, the upper limit of the content of the Yb ₂ O ₃ component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%. From the viewpoint of reducing material costs, the Yb ₂ O ₃ component may not be contained.

As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

When the ZrO ₂ component is contained in an amount of more than 0%, it is an optional component that increases the refractive index and Abbe number of the glass and can improve the devitrification resistance.

On the other hand, when the content of the ZrO ₂ component is 10.0% or less, devitrification due to excessive content of the ZrO ₂ component can be reduced. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 10.0%, more preferably 5.0%, even more preferably 3.0%, and most preferably 1.0%.

As the ZrO ₂ component, ZrO ₂ , ZrF _4, or the like can be used as a raw material.

When the TiO ₂ component is contained at more than 0%, it is an arbitrary component that increases the refractive index of glass.

On the other hand, by reducing the content of the TiO ₂ component to 10.0% or less, the devitrification caused by the excessive content of the TiO ₂ component can be reduced, and the reduction in the transmittance of the glass with respect to visible light (particularly, a wavelength of 500 nm or less) can be suppressed. . Therefore, the upper limit of the content of the TiO ₂ component is preferably 10.0%, more preferably 5.0%, even more preferably 3.0%, and most preferably 1.0%.

When the Nb ₂ O ₅ component is contained at more than 0%, it is an arbitrary component that increases the refractive index of glass.

On the other hand, by reducing the content of the Nb ₂ O ₅ component to 10.0% or less, devitrification caused by excessive Nb ₂ O ₅ content can be reduced, and transmission of glass to visible light (particularly, a wavelength of 500 nm or less) can be suppressed. Rate reduction. Therefore, the upper limit of the content of the Nb ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, even more preferably 3.0%, and most preferably 1.0%.

As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When the Ta ₂ O ₅ component is contained in an amount of more than 0%, it is an optional component that increases the refractive index of the glass and improves the devitrification resistance.

On the other hand, the cost of the glass material is reduced by setting the expensive Ta ₂ O ₅ component to 5.0% or less, and therefore, optical glass can be produced more inexpensively. Therefore, the upper limit of the content of the Ta ₂ O ₅ component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%. From the viewpoint of reducing the material cost, the Ta ₂ O ₅ component may not be contained.

As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

When the content of WO ₃ is greater than 0%, it is an optional component that increases the refractive index of glass and improves the devitrification resistance.

On the other hand, by reducing the content of the WO ₃ component to 5.0% or less, the coloration of the glass due to the WO ₃ component is reduced, and the visible light transmittance is improved. Therefore, the upper limit of the content of the WO ₃ component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%.

As the WO ₃ component, WO ₃ or the like can be used as a raw material.

When the ZnO component is contained at more than 0%, it is an optional component that improves the low-temperature melting property.

On the other hand, by reducing the content of the ZnO component to 30.0% or less, a decrease in the Abbe number or a reduction in devitrification resistance due to an excessive content is suppressed. Therefore, the upper limit of the content of the ZnO component is preferably 30.0%, more preferably 20.0%, still more preferably 15.0%, still more preferably 10.0%, even more preferably 5.0%, even more preferably 3.0%, and most preferably 1.0%.

As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

When the MgO component is contained at more than 0%, it is an optional component that improves the low-temperature melting property.

On the other hand, when the content of the MgO component is 30.0% or less, deterioration in chemical durability or reduction in devitrification resistance due to excessive content of the MgO component is suppressed. Therefore, the upper limit of the content of the MgO component is preferably 30.0%, more preferably 20.0%, still more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%, and most preferably 1.0%.

As the MgO component, MgCO ₃ , MgF _2, or the like can be used as a raw material. When the CaO component is contained in an amount of more than 0%, the effect of improving the low-temperature melting property and suppressing excessive increase in viscosity is easily obtained. Therefore, the content of the CaO component is preferably greater than 0%, the lower limit is more preferably 0.5%, and still more preferably 1.0%. In particular, when the content of the Al ₂ O ₃ component is less than 5.0%, the devitrification resistance is insufficient. Therefore, by setting the lower limit of the CaO component to 2.0% or more, the devitrification resistance can be improved. Therefore, the lower limit of the CaO component is preferably 2.0%, more preferably 3.0%, and still more preferably 5.0%.

On the other hand, when the content of the CaO component is 35.0% or less, deterioration of chemical durability or reduction in devitrification resistance due to excessive content of the CaO component is suppressed. Therefore, the upper limit of the content of the CaO component is preferably 35.0%, more preferably 25.0%, still more preferably 15.0%, still more preferably 10.0%, and still more preferably 5.0%.

CaO component may be used CaCO _3, CaF ₂ and the like as a raw material.

When the SrO component is contained at more than 0%, the low-temperature melting property is improved, and the effect of suppressing excessive increase in viscosity is easily obtained. Therefore, the lower limit of the content of the SrO component is preferably greater than 0%, more preferably 0.5%, and still more preferably 1.0%.

In particular, when the content of the Al ₂ O ₃ component is less than 8.0%, the devitrification resistance is insufficient. Therefore, by setting the lower limit of the SrO component to 2.0% or more, the devitrification resistance can be improved. Therefore, the lower limit of the composition of SrO is preferably 2.0%, more preferably 3.0%, and even more preferably 5.0%.

On the other hand, when the content of the SrO component is 30.0% or less, deterioration of chemical durability or reduction in devitrification resistance due to excessive content of the SrO component is suppressed. Therefore, the upper limit of the content of the SrO component is preferably 30.0%, more preferably 20.0%, still more preferably 10.0%, and still more preferably 5.0%.

As the SrO component, Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

When the BaO component is contained in an amount of more than 0%, the effects of improving low-temperature melting properties and suppressing excessive increase in viscosity can be easily obtained. Therefore, the lower limit of the content of the BaO component is preferably 0% or more, more preferably 0.5%, and still more preferably 1.0%. In particular, when the content of the Al ₂ O ₃ component is less than 8.0%, the devitrification resistance is insufficient. Therefore, by setting the lower limit of the BaO component to 2.0% or more, the devitrification resistance can be improved. Therefore, the lower limit of the composition of BaO is preferably 2.0%, more preferably 3.0%, and still more preferably 5.0%.

On the other hand, when the content of the BaO component is 30.0% or less, deterioration of chemical durability or reduction in devitrification resistance due to excessive content of the BaO component is suppressed. Therefore, the upper limit of the content of the BaO component is preferably 30.0%, more preferably 20.0%, still more preferably 10.0%, and still more preferably 5.0%.

As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like can be used as a raw material.

When the Li ₂ O component is contained in an amount of more than 0%, the low-temperature melting property and the glass formability are improved. Therefore, the lower limit of the content of the Li ₂ O component is preferably greater than 0%, more preferably greater than 0.1%, and still more preferably 0.5%.

On the other hand, when the content of the Li ₂ O component is 20.0% or less, deterioration of chemical durability due to excessive content of the Li ₂ O component is suppressed. Therefore, the upper limit of the content of the Li ₂ O component is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, even more preferably 5.0%, still more preferably 3.0%, and most preferably 1.0%.

As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO _3, or the like can be used as a raw material.

When the Na ₂ O component is contained in an amount of more than 0%, the low-temperature melting property and the glass formability are improved. Therefore, the lower limit of the Na ₂ O content is preferably greater than 0%, more preferably greater than 0.1%, and still more preferably 0.5%.

On the other hand, when the content of the Na ₂ O component is 15.0% or less, deterioration of chemical durability caused by excessive content of the Na ₂ O component is suppressed. Therefore, the upper limit of the content of the Na ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%, and most preferably 1.0%.

As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ and the like can be used as raw materials.

When the K ₂ O component is contained in an amount of more than 0%, it is an optional component that improves low-temperature melting properties and glass formability. Therefore, the lower limit of the content of the K ₂ O component is preferably greater than 0%, more preferably greater than 0.1%, and still more preferably 0.5%.

On the other hand, when the content of the K ₂ O component is 15.0% or less, deterioration of chemical durability caused by excessive content of the K ₂ O component is suppressed. Therefore, the upper limit of the content of the K ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%, and most preferably 1.0%.

As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used as a raw material.

When the GeO ₂ component is contained in an amount of more than 0%, it is an optional component that increases the refractive index of glass and can improve devitrification resistance.

However, the price of GeO ₂ raw materials is high, so when its content is large, the production cost will increase. Therefore, the upper limit of the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%, and still more preferably 0.1%. From the viewpoint of reducing the material cost, the GeO ₂ component may not be contained.

As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

When the Ga ₂ O ₃ component is contained in an amount of more than 0%, it is an optional component that increases the refractive index of the glass and can improve the devitrification resistance.

However, the price of Ga ₂ O ₃ raw materials is high, so when its content is large, the production cost will increase. Therefore, the upper limit of the content of the Ga ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%, and still more preferably 0.1%. From the viewpoint of reducing the material cost, the Ga ₂ O ₃ component may not be contained.

As the Ga ₂ O ₃ component, Ga ₂ O ₃ or the like can be used as a raw material.

When the P ₂ O ₅ component is contained at more than 0%, it is an optional component that lowers the liquidus temperature of the glass and improves the devitrification resistance.

On the other hand, by reducing the content of the P ₂ O ₅ component to 10.0% or less, a reduction in the chemical durability, particularly the water resistance, of the glass is suppressed. Therefore, the upper limit of the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and most preferably 1.0%.

As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ and the like can be used as raw materials.

When the Bi ₂ O ₃ component is contained at more than 0%, it is an arbitrary component that increases the refractive index and lowers the glass transition temperature.

On the other hand, by setting the content of the Bi ₂ O ₃ component to 5.0% or less, the coloration of the glass is suppressed and the devitrification resistance is improved. Therefore, the upper limit of the content of the Bi ₂ O ₃ component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%.

As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

When the TeO ₂ component is contained at more than 0%, it is an arbitrary component that increases the refractive index and lowers the glass transition temperature.

On the other hand, when TeO ₂ melts glass raw materials in a crucible made of platinum or a melting tank formed of platinum in a portion in contact with the molten glass, there is a problem that alloying with platinum may occur. Therefore, the upper limit of the content of the TeO ₂ component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%.

As the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

When the SnO ₂ component is contained at more than 0%, it is an optional component that reduces the oxidation of the molten glass to make the glass clearer and improves the visible light transmittance of the glass.

On the other hand, by reducing the content of the SnO ₂ component to 3.0% or less, it is possible to reduce the coloration of the glass due to reduction or devitrification of the glass due to reduction. In addition, since the SnO ₂ component is reduced and alloyed with the melting equipment (especially noble metals such as Pt), the melting equipment has a longer life. Therefore, the upper limit of the content of the SnO ₂ component is preferably 3.0%, more preferably 1.0%, still more preferably 0.5%, and most preferably 0.1%.

As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

When the Sb ₂ O ₃ component is contained at more than 0%, it is an arbitrary component capable of defoaming the molten glass.

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 is deteriorated. Therefore, the upper limit of the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.7%, still more preferably 0.5%, still more preferably 0.2%, and most preferably 0.1%.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O _7, 5H ₂ O, or the like can be used as a raw material.

Further, the glass fining, the defoaming composition is not limited to the Sb ₂ O ₃ component, known in the glass making art clarifying agents, defoaming agents, or combinations thereof.

When the F component is contained at more than 0%, it is an arbitrary component that increases the Abbe number of the glass, reduces the glass transition temperature, and can improve the devitrification resistance.

However, when the content of the F component is replaced with a part or all of one or two or more of the above-mentioned metal elements, the total amount of F that becomes a fluoride is greater than 15.0%. Since the amount of volatilization increases, it is difficult to obtain a stable optical constant, and it is difficult to obtain a homogeneous glass.

Therefore, the upper limit of the content of the F component is preferably 15.0%, more preferably 12.0%, still more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%, and most preferably 1.0%.

The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

The sum (molar sum) of the content of the RO component (where R is one or more members selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) is preferably 40.0% or less. This suppresses deterioration in chemical durability or reduction in devitrification resistance due to excessive content. Therefore, the moire and upper limit of the RO component are preferably 40.0%, more preferably 30.0%, still more preferably 25.0%, even more preferably 20.0%, even more preferably 15.0%, even more preferably 10.0%, and most preferably 5.0. %.

On the other hand, by setting more than 0%, the effect of improving the meltability of the glass raw material or the effect of suppressing excessive increase in viscosity can be easily obtained. Therefore, the Mohr and lower limit of the RO component is preferably greater than 0%, more preferably 0.5%, and still more preferably 1.0%.

In particular, when the content of the Al ₂ O ₃ component is less than 8.0%, the devitrification resistance is insufficient. Therefore, by setting the lower limit of the RO component to 2.0% or more, the devitrification resistance can be improved. Therefore, the lower limit of the composition of RO is preferably 2.0%, more preferably 3.0%, and still more preferably 5.0%.

When the molar ratio (SiO ₂ + Al ₂ O ₃ ) / (B ₂ O ₃ ) is 0.1 or more, the effect of improving the chemical durability of the glass is easily obtained. Therefore, the lower limit of the molar ratio of (SiO ₂ + Al ₂ O ₃ ) / (B ₂ O ₃ ) is preferably 0.1, more preferably 0.2, still more preferably 0.3, still more preferably 0.4, and most preferably 0.5.

On the other hand, by making this molar ratio 10.0 or less, deterioration of the meltability of glass raw materials or excessive increase in viscosity can be suppressed. Therefore, the upper molar ratio of (SiO ₂ + Al ₂ O ₃ ) / (B ₂ O ₃ ) can also be preferably 10.0, more preferably 8.0, still more preferably 6.0, still more preferably 4.0, and still more preferably 3.0.

When the B ₂ O ₃ component is not contained, the value of (SiO ₂ + Al ₂ O ₃ ) / (B ₂ O ₃ ) is infinite.

When Moire (SiO ₂ + Al ₂ O ₃ ) is 8.0% or more, the effect of improving the chemical durability of the glass is easily obtained. Therefore, the Mohr and lower limit of (SiO ₂ + Al ₂ O ₃ ) is preferably 8.0%, more preferably 10.0%, still more preferably 15.0%, still more preferably 20.0%, and most preferably 25.0%.

On the other hand, by making the Mohr sum to 65.0% or less, it is possible to suppress deterioration of the meltability of the glass raw material or excessive increase in viscosity. Therefore, the mol and upper limit of (SiO ₂ + Al ₂ O ₃ ) is preferably 65.0%, more preferably 60.0%, still more preferably 50.0%, still more preferably 45.0%, and most preferably 40.0%.

When the molar ratio (Ln ₂ O ₃ / Rn ₂ O) is 0.3 or more, the effect of improving the chemical durability of the glass is easily obtained. Therefore, the lower limit of the molar ratio of (Ln ₂ O ₃ / Rn ₂ O) is preferably 0.3, more preferably 0.5, and most preferably 0.7.

In particular, by setting the molar ratio (Ln ₂ O ₃ / Rn ₂ O) to 8.0 or less, it is possible to suppress deterioration of the meltability of the glass raw material or excessive increase in viscosity. Therefore, the upper limit is preferably 8.0, more preferably 5.0, and even more preferably 3.0.

When the Rn ₂ O component is not contained, the value of (Ln ₂ O ₃ / Rn ₂ O) is infinite.

When Mohr and (ZrO ₂ + TiO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ + Bi ₂ O ₃ + TeO ₂ ) are 20.0% or less, the effect of improving devitrification resistance is easily obtained. In addition, It is easy to suppress an excessive decrease in the Abbe number, thereby achieving low dispersion performance. Therefore, the molar upper limit of (ZrO ₂ + TiO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ + Bi ₂ O ₃ + TeO ₂ ) is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%. , More preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%, and most preferably 0.1%.

When the molar ratio (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) is 0.2 or more, the effect of improving the chemical durability of the glass is easily obtained. Therefore, the lower limit of the molar ratio of (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) is preferably 0.2, more preferably 0.3, still more preferably 0.4, and most preferably 0.5. .

On the other hand, by setting the Mohr ratio to 3.0 or less, it is possible to suppress deterioration of the meltability of the glass raw material or excessive increase in viscosity. Therefore, the upper limit of the molar ratio of (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) is preferably 3.0, more preferably 2.0, and even more preferably 1.5.

When the components RO, Rn ₂ O, and B ₂ O ₃ are not contained, the value of (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) is set to infinite. Big.

When the molar ratio (Ln ₂ O ₃ / RO) is 0.1 or more, the effect of improving the chemical durability of the glass is easily obtained. Therefore, the lower limit of the molar ratio of (Ln ₂ O ₃ / RO) is preferably 0.1, more preferably 0.2, and still more preferably 0.3.

When the RO component is not contained, the (Ln ₂ O ₃ / RO) value is infinitely large.

When the molar product (BaO × Gd ₂ O ₃ ) is less than 5.0, the effect of suppressing both the glass specific gravity and the cost is easily obtained. Therefore, the upper limit of the Moire product of (BaO × Gd ₂ O ₃ ) is preferably lower than 5.0, more preferably 3.0, further preferably 2.0, even more preferably 1.0, and most preferably 0.1.

<About ingredients that should not be contained>

Hereinafter, components which should not be contained in the optical glass of the present invention and components which are not preferably contained will be described.

Other components may be added as needed within a range that does not impair the glass characteristics of the invention of the present application. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, each of the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo has a separate or composite When a small amount is contained, the glass is also colored and absorbs a specific wavelength in the visible region. Therefore, it is particularly preferable that the glass is substantially not contained in optical glass using a wavelength in the visible region.

The Nd ₂ O ₃ component has a strong influence on the coloration of the glass, and therefore, it is ideally substantially free of the Nd ₂ O ₃ component, that is, it is not contained at all except for inevitable mixing.

The Er ₂ O ₃ component has a strong influence on the coloration of glass, and therefore, it is ideally substantially free of the Er ₂ O ₃ component, that is, it is completely free of it except for inevitable mixing.

In addition, lead compounds such as PbO are those having a high environmental burden, and therefore, they are ideally not substantially contained, that is, they are not contained at all except for inevitable mixing.

In addition, arsenic compounds such as As ₂ O ₃ are those having a high environmental burden, and therefore are ideally not substantially contained, that is, they are not contained at all except for inevitable mixing.

Furthermore, the components of Th, Cd, Tl, Os, Be, and Se have been in the trend of being controlled and used as harmful chemical substances in recent years, not only in glass manufacturing steps, but also until processing steps and disposal after productization. , All need measures on environmental protection measures. Therefore, when the environmental impact is taken into consideration, these components are preferably not substantially contained.

〔Physical Properties〕

The optical glass of the present invention preferably has a medium refractive index and a high Abbe number (low dispersion). In particular, the lower limit of the refractive index (nd) of the optical glass of the present invention is preferably 1.58, more preferably 1.60, still more preferably 1.62, still more preferably 1.63, and most preferably 1.64. The upper limit of the refractive index (nd) is preferably 1.80, more preferably 1.75, even more preferably 1.70, and most preferably 1.68.

In addition, the lower limit of the Abbe number ( v d) of the optical glass of the present invention is preferably 35, more preferably 38, still more preferably 40, still more preferably 45, and most preferably 50. The upper limit of the Abbe number ( v d) is preferably 65, but preferably 64, more preferably 63, still more preferably 62, still more preferably 61, and most preferably 60.

By having such a medium refractive index, a large amount of light refraction can be obtained even under the condition that the optical element is thinned. Further, by having such a low dispersion, it is possible to reduce focus deviation (chromatic aberration) caused by the wavelength of light when used as a single lens. Therefore, for example, when an optical system is configured by combining with an optical element having a high dispersion (low Abbe number), it is possible to reduce aberrations as a whole of the optical system, thereby achieving higher imaging characteristics and the like.

In this way, the optical glass of the present invention is effective in optical design, and especially when constituting an optical system, it can achieve miniaturization of the optical system while expanding the optical system while expanding the degree of freedom in optical design.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the optical glass of the present invention has a specific gravity of 5.00 or less. This reduces the quality of the optical element or the optical equipment using the optical element, so that it can contribute to weight reduction of the optical equipment. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.70, and even more preferably 4.50. In addition, the specific gravity of the optical glass of the present invention is generally approximately 2.80 or more, more specifically 3.00 or more, and more specifically 3.20 or more.

The specific gravity of the optical glass of the present invention is measured based on the Japanese Optical Glass Industry Standard JOGIS05-1975 "Method for Measuring Specific Gravity of Optical Glass".

Ideally, the multiplication (d × RA) value of the glass specific gravity (d) and the powder method acid resistance level (RA) is low. More specifically, the (d × RA) multiplication value of the present invention is 15.0 or less.

This makes it possible to produce a lens having excellent acid resistance and a low specific gravity. Therefore, it is easy to produce an optical element that is lightweight and suitable for use in a vehicle or a surveillance camera and has resistance to acid rain and the like.

Therefore, the upper limit of the multiplication value of the device (d × RA) of the present invention is preferably 15.0, 14.0, 13.0, 12.0, 11.0, 10.5, or 10.0. .

In addition, the lower limit of the multiplication value of the optical glass (d × RA) of the present invention is not particularly limited, but it is generally approximately 3.0 or more, more specifically 5.0 or more, and more specifically 6.5 or more.

The optical glass of the present invention preferably has high acid resistance. In particular, it is preferable that the chemical durability (acid resistance) measured by the glass powder method based on JOGIS06-1999 is preferably 1 to 4 and more preferably 1 to 3.

With this, in addition to improving the processability of optical glass, when the glass is used for automotive applications, the glass is less blurred due to acid rain and the like. Therefore, it is possible to more easily manufacture glass-derived optical elements.

Here, the term "acid resistance" refers to the durability of acid against glass erosion. The acid resistance can be measured by the Japan Optical Glass Industry Standard "Measurement Method for Chemical Durability of Optical Glass" JOGIS06-1999. In addition, the so-called "chemical durability (acid resistance) measured by powder method is grade 1 to 3" refers to the chemical durability (acid resistance) performed according to JOGIS06-1999 as a standard to determine the weight loss of the sample before and after Rate, less than 0.65 mass%.

In addition, "level 1" of chemical durability (acid resistance) means that the weight loss rate of the sample mass before and after the measurement is less than 0.20% by mass, and "level 2" means that the weight loss rate of the sample mass before and after the measurement is 0.20% by mass or more and Below 0.35 mass%, "level 3" means that the weight loss of the sample before and after the measurement is 0.35 mass% or more and less than 0.65 mass%, and "level 4" means that the weight loss of the sample before and after the measurement is 0.65 mass% Above and below 1.20% by mass, "level 5" means that the weight loss rate of the sample before and after measurement is 1.20% by mass or more and less than 2.20% by mass, and "level 6" means that the weight loss rate of the sample before and after measurement is 2.20 Above mass%.

The optical glass of the present invention preferably has high resistance to devitrification, and more specifically, it has a lower liquidus temperature.

That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C, more preferably 1150 ° C, and still more preferably 1100 ° C. Thereby, even if the melted glass flows out at a lower temperature, the crystallization of the produced glass can be reduced. Therefore, devitrification when the glass is formed from a molten state can be reduced. For optical elements such as glass, It can reduce the influence of optical characteristics. In addition, the glass can be formed even if the melting temperature of the glass is lowered. Therefore, by suppressing the energy consumed during the glass forming, the manufacturing cost of the glass can be reduced.

On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but most of the liquidus temperature of the glass obtained by the present invention is approximately 800 ° C or higher, specifically 850 ° C or higher, and more specifically Above 900 ° C. In addition, the "liquid phase temperature" in this specification refers to holding in a temperature-inclined furnace with a temperature gradient of 1000 ° C to 1150 ° C for 30 minutes, taking it out of the furnace for cooling, and observing the presence of crystals with a microscope at a magnification of 100 times To the lowest temperature of crystallization.

〔Production method〕

The optical glass of the present invention is produced, for example, by the following method. That is, by uniformly mixing the above raw materials so that each component is within a predetermined content range, the prepared mixture is put into a platinum crucible, and the melting difficulty of the glass composition is determined by using an electric furnace at 1100 ° C to 1340 ° C Melt in the temperature range for 2 hours to 6 hours. After stirring and homogenizing, lower the temperature to an appropriate temperature, and then cast it into a model for slow cooling.

[Glass forming]

The glass of the present invention can be melt-formed by a known method. In addition, the method of forming a molten glass is not limited.

[Glass molded body and optical element]

The glass of the present invention can be formed into a glass formed body by, for example, grinding and polishing processing methods. That is, a glass shaped body can be manufactured by mechanically processing glass, such as grinding and polishing. In addition, the method of manufacturing a glass forming body is not limited to the above-mentioned method.

Thereby, since the glass molded body formed from the glass of the present invention is excellent in durability, the processability is good, and glass degradation due to acid rain or the like is small, and therefore, it can be used in automotive applications and the like.

[Example]

Tables 1 to 5 show the compositions of the glass examples and comparative examples of the present invention, the refractive index (nd), Abbe number ( v d), specific gravity (d), powder method acid resistance level (RA) of these glasses, Liquid temperature. In addition, the following examples are intended for illustrative purposes, and the present invention is not limited to these examples.

The glasses of the examples and comparative examples of the present invention are prepared as follows: As the raw materials of each component, the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, metaphosphoric acid compounds and other high-purity raw materials used in general optical glasses are selected. , Weigh and mix uniformly to achieve the composition ratio of each embodiment shown in the table, and then put it into a platinum crucible. The melting difficulty of the glass composition is in an electric furnace at a temperature range of 1100 ° C to 1350 ° C. After 2 hours to 5 hours of internal melting, the mixture is homogenized by stirring, and then cast into a mold or the like, and then slowly cooled to produce glass.

Here, the glass refractive index and Abbe number of the examples and comparative examples were measured based on the standards of the Japan Optical Glass Industry Association JOGIS01-2003. Here, the refractive index and the Abbe number are determined by measuring a glass obtained by slow-cooling and lowering the temperature to -25 ° C / hr.

The specific gravity of the glass of the examples and comparative examples was measured based on the Japanese Optical Glass Industry Standard JOGIS05-1975 "Method for Measuring the Specific Gravity of Optical Glass".

The acid resistance of the glass in the examples and comparative examples was measured using the standard "Measurement method for chemical durability of optical glass" JOGIS06-1999, a standard of the Japan Optical Glass Association. That is, a glass sample broken into a particle size of 425 μm to 600 μm is placed in a pycnometer and put into a platinum cage. The platinum cage was placed in a round bottom flask made of quartz glass with a 0.01 N nitric acid aqueous solution and treated in a boiling water bath for 60 minutes. Calculate the reduction rate (mass%) of the glass sample after the treatment, and set the reduction rate (mass%) below 0.20 to level 1 and the reduction rate (0.20 to 0.35) to level 2 and reduce When the rate is 0.35 to less than 0.65, the level is 3; when the rate is 0.65 to less than 1.20, the level is 4; when the rate is 1.20 to less than 2.20, the level is 5; In the case of 2.20 or higher, level 6 is set. In this case, the smaller the number of stages, the better the acid resistance of the glass.

For the glass liquidus temperature of the examples and comparative examples, determine whether the temperature is maintained in a temperature-inclined furnace with a temperature gradient of 1000 ° C. to 1150 ° C. for 30 minutes, and then take it out of the furnace and cool it. The lowest temperature at which crystallization was not observed during crystallization.

In addition, when it describes as "1000 degrees C or less", it means that a crystal | crystallization cannot be seen at least 1000 degreeC.

As shown in the table, the optical glass of the embodiment of the present invention has a molar sum (SiO ₂ + B ₂ O ₃ ) of 40.0% to 75.0%, and an Ln ₂ O ₃ component (wherein, Ln is selected from La, Gd, Y Mo of the group consisting of 1 or more) and Mo of 3.0% to 25.0%; Rn ₂ O component (where Rn is one or more members selected from the group consisting of Li, Na, and K) The ear sum is more than 0% to 25.0%, so that an optical glass having excellent durability and a desired optical constant can be obtained.

In addition, the optical glass of the embodiment of the present invention has a refractive index (nd) of 1.60 or more, more specifically 1.64 or more, and the refractive index (nd) is 1.80 or less, which is within a desired range.

In addition, in the optical glass according to the embodiment of the present invention, the Abbe number ( v d) is 65 or less, and the Abbe number ( v d) is 35 or more, more specifically, 40 or more, which is within a desired range .

In addition, the optical glass of the present invention can form a stable glass, and it is difficult to cause devitrification when making glass. These effects can also be estimated by the optical glass liquid temperature of the present invention being 1150 ° C or lower, and more specifically 1100 ° C or lower.

In addition, the specific gravity of the optical glass in the examples of the present invention is 4.00 or less, and more specifically 3.60 or less. Therefore, it can be seen that the specific gravity of the optical glass of the embodiment of the present invention is small.

In addition, the chemical durability (acid resistance) of the optical glass according to the embodiment of the present invention, as measured by the powder method, are all grades 1 to 4, which are within a desired range.

Furthermore, in the optical glass of the embodiment of the present invention, the glass specific gravity (d) and the powder method acid resistance level (RA) multiplication d × RA value are all 15.0 or less.

Therefore, in the optical glass according to the embodiment of the present invention, the refractive index (nd) and Abbe number ( v d) are within a desired range, and the specific gravity has a value of 5.00 or less, and the chemical durability (acid resistance) measured by the powder method ) Are grades 1 to 4, and the multiplication d × RA value of the glass specific gravity (d) and the powder method acid resistance grade (RA) is within a desired range. Therefore, it can be seen that both the optical glass and the chemical durability of the optical glass according to the embodiment of the present invention are excellent.

On the other hand, in the optical glass of the comparative example, the molar sum of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Lu) is less than 3.0%. Since the specific gravity (d) and the powder method acid resistance level (RA) multiplication d × RA value are greater than 15.0, the specific gravity is light and a glass material having excellent chemical durability cannot be obtained.

Furthermore, the optical glass according to the embodiment of the present invention is used to form a glass block, and the glass block is ground and polished to be processed into a lens and a cymbal shape. As a result, various lenses and chirped shapes can be stably processed.

In the foregoing, the present invention has been described in detail for the purpose of illustration. However, it should be understood that the purpose of this embodiment is for illustration, and various changes can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims (13)

An optical glass, measured in mole%, containing: Moore and (SiO ₂ + B2O ₃ ) is 40.0% to 75.0%; the molar sum of the Ln ₂ O ₃ component is 3.0% to 25.0%, where Ln is One or more selected from the group consisting of La, Gd, Y, and Lu; the molar sum of the Rn ₂ O component is more than 0% to 25.0%, where Rn is selected from the group consisting of Li, Na, and K 1 or more of the above; the multiplication of the specific gravity (d) of the glass and the acid resistance level (RA) of the powder method d × RA is 15.0 or less; the aforementioned optical glass has a refractive index (nd) of 1.58 or more and 1.80 or less, and 35 or more Abbe number ( v d) below 65. The optical glass according to claim 1, further comprising the following components in terms of mole%: SiO ₂ component 5.0% to 60.0%, B ₂ O ₃ component 0% to 70.0%, and Al ₂ O ₃ component 0% To 25.0%, La ₂ O ₃ component 0% to 25.0%, Y ₂ O ₃ component 0% to 25.0%, Gd ₂ O ₃ component 0% to 25.0%, Lu ₂ O ₃ component 0% to 5.0%, Yb ₂ O ₃ component 0% to 5.0%, ZrO ₂ component 0% to 10.0%, TiO ₂ component 0% to 10.0%, Nb ₂ O ₅ component 0% to 10.0%, Ta ₂ O ₅ component 0% to 5.0%, WO ₃ components 0% to 5.0%, ZnO component 0% to 30.0%, MgO component 0% to 30.0%, CaO component 0% to 35.0%, SrO component 0% to 30.0%, BaO component 0% to 30.0%, Li ₂ 0% to 20.0% of O component, 0% to 15.0% of Na ₂ O component, 0% to 15.0% of K ₂ O component, 0% to 10.0% of GeO ₂ component, 0% to 10.0% of Ga ₂ O ₃ component, P ₂ O ₅ component 0% to 10.0%, Bi ₂ O ₃ component 0% to 5.0%, TeO ₂ component 0% to 5.0%, SnO ₂ component 0% to 3.0%, and Sb ₂ O ₃ component 0% to 1.0%. The optical glass according to claim 1 or 2, wherein the molar ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ is 0.1 or more. The optical glass according to claim 1 or 2, wherein Mohr and (SiO ₂ + Al ₂ O ₃ ) are 8.0% to 65.0%. The optical glass according to claim 1 or 2, wherein the molar ratio (Ln ₂ O ₃ / Rn ₂ O) is 0.3 or more. The optical glass according to claim 1 or 2, wherein Mor and (ZrO ₂ + TiO ₂ + Nb ₂ O ₅ + Ta ₂ O ₅ + WO ₃ + Bi ₂ O ₃ + TeO ₂ ) are 0% to 20.0% . The optical glass according to claim 1 or 2, wherein the molar ratio (Ln ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ) / (RO + Rn ₂ O + B ₂ O ₃ ) is 0.2 to 3.0. The optical glass according to claim 1 or 2, wherein the molar product (BaO × Gd ₂ O ₃ ) is less than 5.0%.     The optical glass according to claim 1 or 2, wherein the chemical durability measured by the powder method has grades 1 to 4, and the aforementioned chemical durability is acid resistance.         The optical glass according to claim 1 or 2, wherein the molar sum of the RO component is 40.0% or less. In the formula, R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba.         A preform comprising the optical glass according to claim 1 or 2.         An optical element composed of the optical glass according to claim 1 or 2.         An optical device including the optical element according to claim 12.