CN106915901A - A kind of optical glass, preform and optical element - Google Patents

Abstract

The invention can obtain a refractive index (n)_d) And Abbe number (v)_d) All within the required range, and the partial dispersion ratio (theta g, F) is small. The optical glass contains SiO in terms of mass% of the composition in terms of oxides₂20.0 to 60.0% of Nb₂O₅15.0 to 50.0% of a component, and a partial dispersion ratio (theta g, F) and an Abbe number (v)_d) Satisfy (-0.00256 × v)_d+0.637)≦(θg，F)≦(‑0.00256×ν_d+ 0.684).

Description

A kind of optical glass, preform and optical element

technical field

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

Background technique

Optical systems such as digital still cameras and video cameras have more or less a phenomenon called color fringing called aberration. This aberration is divided into monochromatic aberration and chromatic aberration, especially chromatic aberration largely depends on the material properties of the lens used in the optical system.

Chromatic aberration is usually corrected by combining a low-dispersion convex lens and a high-dispersion concave lens, but this combination can only correct aberrations in the red and green regions, leaving aberrations in the blue region. This aberration in the blue region that cannot be removed is called the secondary spectrum. When correcting the secondary spectrum, it is necessary to consider the movement of the g-line (435.835nm) in the blue region when performing optical design. At this time, the partial dispersion ratio (θg, F) is used as an index of optical characteristics that attracts attention in optical design. In the above-mentioned optical system combining a convex lens with low dispersion and a concave lens with high dispersion, by using an optical material with a large partial dispersion ratio (θg, F) for the lens on the low dispersion side, the lens on the high dispersion side The use of optical materials with a small partial dispersion ratio (θg,F) in , so that the secondary spectrum can be well corrected.

The partial dispersion ratio (θg, F) is represented by the following formula (1).

θg, F=(n _g -n _F )/(n _F -n _C )······(1)

In optical glass, there is an approximately linear relationship between the partial dispersion ratio (θg, F) representing partial dispersion in the short-wavelength region and the Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio of NSL7 and _PBM2 and A The straight line representation of two points of Bei number is called standard line (refer to Figure 1). The standard glass used as the standard line reference differs depending on the optical glass manufacturer, but each manufacturer uses almost the same inclination and intercept to define (NSL7 and PBM2 are optical glass manufactured by Ohara Co., Ltd., and PBM2’s The Abbe number (ν _d ) is 36.3, and the partial dispersion ratio (θg, F) is 0.5828. The Abbe number (ν _d ) of NSL7 is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.).

In recent years, glass having an Abbe number (ν _d ) of 30 to 47 is often used as an optical material with a small partial dispersion ratio (θg, F) according to the needs of optical design. Here, optical glasses described in Patent Documents 1 to 3, for example, are known as conventional glasses having an Abbe number (ν _d ) of 30 to 47.

On the other hand, in an optical material with a small partial dispersion ratio (θg, F), the components (Nb ₂ O ₅ component, B ₂ O ₃ component, Li ₂ O component) contained in order to obtain good optical characteristics, There is a tendency for the chemical durability to decrease. In these optical glasses, during processing and storage, fog or interference films are sometimes produced on the surface of the glass due to polishing fluid, water vapor in the atmosphere, and carbon dioxide gas. These phenomena are generally called "white mold" or "white mold". blue mold", causing problems with significant defects when used as a lens.

In addition, the automotive lenses and interchangeable lenses used in recent years can often be used in various environments, so an optical glass that does not generate mildew is required.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-029777

[Patent Document 2] Japanese Patent Application Laid-Open No. 2008-239478

[Patent Document 3] Japanese Patent Application Laid-Open No. 2003-054983

The technical problem to be solved by the invention

However, the glass disclosed in Patent Document 1 has a large partial dispersion ratio and is not sufficient for use as a lens for correcting the secondary spectrum. Also, the glass disclosed in Patent Document 1 cannot be said to have sufficient optical properties because of its low transmittance.

In addition, although the glass disclosed in Patent Document 2 has a relatively small partial dispersion ratio, its Abbe number is relatively large, so a glass having a smaller Abbe number is required. In addition, the stability of the glass is poor and the production efficiency is significantly reduced.

In addition, the glass disclosed in Patent Document 3 has a low glass transition temperature (Tg), but the stability of the glass is poor, so it cannot be said that it has sufficient chemical durability, especially surface weather resistance.

The present invention is accomplished in view of the above problems, and its purpose is to obtain an optical glass whose refractive index ( _nd ) and Abbe number (ν _d ) are all within the required range, and whose partial dispersion ratio (θg, F) is small .

Another object of the present invention is to obtain an optical glass having good chemical durability, especially surface weather resistance.

Contents of the invention

In order to solve the above problems, the inventors of the present invention conducted intensive experiments and studies, and found that glass containing SiO ₂ and Nb ₂ O ₅ can obtain a glass with a high refractive index and a low Abbe glass within the desired range. number (high dispersion) and lower partial dispersion ratio glass, thus completing the present invention.

In addition, the inventors of the present invention found that glass having excellent chemical durability, particularly surface weather resistance, can be obtained by including K ₂ O component as an essential component in glass containing SiO ₂ component and Nb ₂ O ₅ component.

(1) An optical glass characterized in that, calculated by mass % of the composition in terms of oxides,

Contains 20.0 to 60.0% of SiO ₂ components,

Nb ₂ O ₅ composition 10.0～50.0%,

In addition, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) satisfy the relationship of (-0.00256×ν _d +0.637)≦(θg, F)≦(-0.00256×ν _d +0.684).

(2) The optical glass according to (1) above, which contains 0 to 20.0% of a ZrO ₂ component in terms of mass % of the composition in terms of oxides.

(3) The optical glass according to (1) or (2) above, which contains 0 to 15.0% of a K ₂ O component in terms of mass % of the composition in terms of oxides.

(4) The optical glass according to any one of the above (1) to (3), characterized in that the surface weather resistance grade is grade 1 or grade 2.

(5) The optical glass according to any one of the above (1) to (4), characterized in that,

Calculated by mass% of the composition in terms of oxides,

The ZnO composition is 0-25.0%,

The Li ₂ O composition is 0 to 20.0%,

The Na ₂ O component is 0-20.0%,

The B ₂ O ₃ component is 0 to 20.0%,

The _TiO2 composition is 0 to 15.0%,

MgO composition is 0-10.0%,

CaO composition is 0-10.0%,

The SrO composition is 0-10.0%,

The BaO composition is 0-10.0%,

The composition of La ₂ O ₃ is 0-10.0%,

The Gd ₂ O ₃ composition is 0 to 10.0%,

The Y ₂ O ₃ composition is 0 to 10.0%,

Yb ₂ O ₃ composition is 0-10.0%,

The composition of _Ta2O5 is _0-10.0 %,

The WO ₃ component is 0 to 10.0%,

The P ₂ O ₅ composition is 0 to 10.0%,

The composition of _GeO2 is 0~10.0%,

Al ₂ O ₃ composition is 0-10.0%,

The Ga ₂ O ₃ composition is 0 to 10.0%,

The composition of Bi ₂ O ₃ is 0-10.0%,

The TeO2 composition is _0-5.0 %,

_SnO2 composition is 0~5.0%,

The Sb ₂ O ₃ component is 0 to 1.0%.

(6) The optical glass according to any one of the above (1) to (5), wherein the mass ratio (Li ₂ O+K ₂ O)/(ZrO ₂ +Li ₂ O) is greater than 0 to less than 2.5.

(7) The optical glass according to any one of (1) to (6) above, wherein the sum of the contents of the SiO ₂ component and the Nb ₂ O ₅ component exceeds 50.0%.

(8) The optical glass according to any one of the above (1) to (7), characterized in that,

Calculated in standard mass % of oxides,

The sum of the mass of Ln ₂ O ₃ components is 0 to 15.0%. In the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb,

The sum of the mass of the RO components is 0 to 30.0%. In the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba,

The sum of the mass of the Rn ₂ O components is 0 to 30.0%. In the formula, Rn is one or more selected from the group consisting of Li, Na, and K.

(9) The optical glass according to any one of (1) to (8) above, which has a refractive index (n _d ) of 1.60 to 1.78 and an Abbe number (ν _d ) of 28 to 47 ).

(10) The optical glass according to any one of (1) to (9) above, wherein the wavelength (λ ₈₀ ) at which the spectral transmittance shows 80% is 420 nm or less, and the wavelength at which the spectral transmittance shows 5% (λ ₅ ) is 365 nm or less.

(11) A preform for polishing and/or precision press molding, comprising the optical glass described in any one of (1) to (10) above.

(12) An optical element comprising the optical glass described in any one of (1) to (10) above.

Invention effect

According to the present invention, it is possible to obtain an optical glass with a refractive index ( _nd ) and Abbe number (ν _d ) within the required range, and with relatively low partial dispersion.

In addition, according to the present invention, it is possible to obtain at a lower price a kind of refractive index ( _nd ) and Abbe number (ν _d ) that are both within the required range, and reduce the milky white produced in the reheat press molding process. and devitrified optical glass.

In addition, according to the present invention, a kind of refractive index (n _d ) and Abbe number (ν _d ) can be obtained within the required range, and has a high refractive index and a low Abbe number (compared to High dispersion) and low partial dispersion ratio glass, and while maintaining a low partial dispersion ratio (θg, F), an optical glass with good chemical durability can be obtained.

Description of drawings

FIG. 1 is a schematic diagram showing a standard line expressed in a rectangular coordinate system having a partial dispersion ratio (θg, F) on the vertical axis and Abbe's number (ν _d ) on the horizontal axis.

Fig. 2 is a schematic diagram of the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the examples of the present invention.

detailed description

_The optical glass of the present invention contains 20.0 to 60.0% of the _SiO2 component and 10.0 to 50.0% of the _Nb2O5 component in terms of mass % of the composition in terms of oxides, and the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) satisfy the relationship of (-0.00256×ν _d +0.637)≦(θg, F)≦(-0.00256×ν _d +0.684).

Among optical glasses containing a SiO ₂ component and a Nb ₂ O ₅ component, glass having a high refractive index within a required range, a low Abbe number (high dispersion) and a low partial dispersion ratio can be obtained.

Therefore, it is possible to obtain a high refractive index (n _d ) and a low Abbe number (ν _d ) and a low partial dispersion ratio (θg, F) which helps to reduce the chromatic aberration of the optical system. Optical glass with aberrations.

_In particular, the first optical glass contains 20.0 to 60.0% of an _SiO2 component, 20.0 to 45.0% of an _Nb2O5 component, and 1.0 to 20.0% of a ZrO2 component, and has a composition of 1.60 to 1.75 _% in mass % of the composition in terms of oxides. Refractive index (n _d ) below and Abbe number (ν _d ) between 30 and 47, partial dispersion ratio (θg, F) and Abbe number (ν _d ) satisfy (-0.00256×ν _d +0.637)≦( θg, F)≦(-0.00256×ν _d +0.684).

_In the first optical glass, in glasses containing _SiO2 components, _Nb2O5 components, and ZrO2 components, it is possible to obtain a glass having a high refractive index and a low Abbe number (high dispersion ₎ within the required range and a low partial Dispersion ratio glass.

Therefore, a high refractive index (n _d ) and a low Abbe number (ν _d ) can be obtained, and the partial dispersion ratio (θg, F) is low and helps to reduce the chromatic aberration of the optical system. Optical glass with aberrations.

In addition, the second optical glass contains 20.0 to 60.0% of SiO ₂ components, 10.0 to 50.0% of Nb ₂ O ₅ components, and more than 0.1 to 15.0% of K ₂ O components in terms of mass % of the composition in terms of oxides, and has a partial dispersion ratio of (θg, F) and Abbe number (ν _d ) satisfy the relationship of (-0.00256×ν _d +0.637)≦(θg, F)≦(-0.00256×ν _d +0.684), and the surface weather resistance level is grade 1 or level 2.

_In the _second optical glass, among glasses containing _SiO2 components, _Nb2O5 components, and K2O components, a glass having a high refractive index and a low Abbe number (high dispersion) within the required range can be obtained. And glass with low partial dispersion ratio, especially by containing K ₂ O component, it is easy to adjust the required optical constants, and can reduce the occurrence of mold spots while maintaining a low partial dispersion ratio (θg, F).

Therefore, a high refractive index (n _d ) and a low Abbe number (ν _d ) can be obtained, and the partial dispersion ratio (θg, F) is low and helps to reduce the optical system. Chromatic aberration, optical glass with excellent chemical durability, especially surface weather resistance.

Hereinafter, although embodiment of the optical glass of this invention is demonstrated concretely, this invention is not limited to the following embodiment at all, It can change suitably and implement within the objective range of this invention. In addition, description may be appropriately omitted for parts that are repeatedly described, but this does not limit the gist of the invention.

[glass ingredient]

Hereinafter, the composition range of each component which comprises the optical glass of this invention is demonstrated. In this specification, unless otherwise specified, the content of each component is represented by mass % with respect to the glass total mass of an oxide conversion composition. Here, the "composition in terms of oxides" means that when it is assumed that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass composition of the present invention are all decomposed and converted into oxides during melting, The total mass of the generated oxides is taken as 100% by mass to represent the composition of each component contained in the glass.

<About essential ingredients and optional ingredients>

The SiO ₂ component is an essential component for reducing devitrification (crystal formation) that is not suitable for optical glass because it can promote stable glass formation and lower the liquidus temperature.

In particular, by making the content of the SiO ₂ component 20.0% or more, glass having good devitrification resistance can be obtained without greatly increasing the partial dispersion ratio. In addition, it is possible to reduce devitrification and coloration at the time of forming glass and at the time of reheating. Therefore, the content of the _SiO2 component is preferably 20.0% as the lower limit, more preferably 23.0% as the lower limit, more preferably 25.0% as the lower limit, and more preferably 27.0% as the lower limit. More preferably, the lower limit is 30.0%, and more preferably, 32.0% is the lower limit.

On the other hand, by making the content of the SiO ₂ component 60.0% or less, the required high refractive index can be easily obtained by making it difficult to lower the refractive index, and an increase in the partial dispersion ratio can be suppressed. Moreover, according to this, the fall of the meltability of a glass raw material can be suppressed. Therefore, the content of the _SiO2 component is preferably 60.0% as the upper limit, more preferably 55.0% as the upper limit, more preferably 50.0% as the upper limit, and more preferably 48.0% as the upper limit. More preferably, the upper limit is 47.0%, more preferably 45.0%, still more preferably 44.0%, and still more preferably 43.0%.

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

The Nb ₂ O ₅ component is an essential component that increases the refractive index, reduces the Abbe number and the partial dispersion ratio, and improves devitrification resistance.

In particular, by making the content of the Nb ₂ O ₅ component 10.0% or more, increasing the refractive index to a target optical constant, and adjusting the components within the scope of the present invention, the abnormal dispersion can be reduced. Therefore, the lower limit of the _{Nb2O5 component} content is preferably 10.0%, more preferably 15.0%, more preferably 20.0%, and more preferably 22.0%. The lower limit is more preferably 23.0%.

On the other hand, by making the content of the Nb ₂ O ₅ component 50.0% or less, the material cost of the glass can be reduced. In addition, it is possible to suppress a rise in the melting temperature at the time of glass production, and to reduce devitrification caused by an excessive content of the Nb ₂ O ₅ component. In addition, reduction in chemical durability of glass can also be improved. Therefore, the content of the _Nb2O5 component is preferably _50.0 % as the upper limit, more preferably 45.0% as the upper limit, more preferably 43.0% as the upper limit, and more preferably 41.5% as the upper limit. The upper limit is more preferably 40.0%, more preferably 35.0%, and more preferably 30.0%.

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

_The ZrO2 component is a component that can increase the refractive index and Abbe number of the glass, reduce the partial dispersion ratio, and improve the devitrification resistance when the content exceeds 0%, and it is an essential component in the first optical glass in particular. . _In addition, by containing the ZrO2 component, devitrification and coloring at the time of glass formation and reheating can be reduced. Therefore, the content of the ZrO ₂ component is more preferably 1.0% or more, more preferably more than 1.0%, more preferably more than 3.0%, and more preferably more than 5.0%.

_On the other hand, by making the content of the ZrO2 component 20.0% or less, devitrification can be reduced and more uniform glass can be obtained relatively easily. Therefore, the content of the _ZrO2 component is preferably 20.0% as the upper limit, more preferably 18.0% as the upper limit, more preferably 15.0% as the upper limit, and more preferably 13.0% as the upper limit. More preferably, 10.0% is the upper limit.

As the ZrO ₂ component, ZrO ₂ , ZrF ₄ , etc. can be used as a raw material.

The K ₂ O component is an arbitrary component that can improve the meltability of glass raw materials and lower the liquidus temperature when the content exceeds 0%. In particular, in the second optical glass, the K ₂ O component is an essential component capable of improving chemical durability.

In particular, mold stains in glass can be effectively improved by making the content of the K ₂ O component larger than 0%. Therefore, the content of the K ₂ O component is preferably greater than 0%, more preferably greater than 0.1%, more preferably greater than 0.3%, more preferably greater than 0.5%, and more ideally greater than 0.5%. 1.0%.

On the other hand, by making the content of the K ₂ O component 15.0% or less, the increase in the partial dispersion ratio can be suppressed, devitrification can be reduced, and the chemical durability can hardly be reduced. Therefore, the content of the K2O component is preferably at most 15.0%, more preferably at most 10.0%, more preferably less _than 10.0%, more preferably less than 8.0%, still more preferably less than 5.0%. .

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

The ZnO component is an arbitrary component that is inexpensive, can improve devitrification resistance, and can lower the glass transition temperature when the content exceeds 0%. Therefore, the content of the ZnO component is preferably greater than 0%, more preferably greater than 0.5%, and more preferably greater than 1.0%.

On the other hand, by making the content of the ZnO component 25.0% or less, devitrification and coloring during glass formation and reheating can be reduced, and chemical durability can be improved. Therefore, the content of the ZnO component is preferably 25.0% or less, more preferably 20.0% or less, more preferably less than 18.0%, more preferably less than 14.0%, more preferably less than 13.0%, and more preferably less than 13.0%. Ideally, it is less than 10.0%.

The Li ₂ O component is an arbitrary component that can lower the partial dispersion ratio, improve the transmittance, lower the liquidus temperature, and improve the meltability of the glass raw material when the content exceeds 0%. Therefore, the content of the Li ₂ O component is more preferably more than 0%, more preferably more than 1.0%, more preferably more than 3.0%, and more preferably more than 5.0%.

On the other hand, by making the content of the Li ₂ O component 20.0% or less, the decrease in the refractive index can be suppressed, the chemical durability can hardly decrease, and the devitrification caused by the excessive content can be reduced.

Therefore, the content of the _Li2O component is preferably 20.0% or less, more preferably 15.0% or less, more preferably 13.0% or less, more preferably less than 10.0%, still more preferably less than 8.0% .

As a _Li2O component, _Li2CO3 , _LiNO3 , _LiF etc. can be used as a raw material.

The Na ₂ O component is an optional component that can lower the partial dispersion ratio, lower the liquidus temperature, and improve the meltability of the glass raw material when the content exceeds 0%. Therefore, the content of the Na ₂ O component is more preferably more than 0%, more preferably more than 1.0%, more preferably more than 3.0%, and more preferably more than 5.0%.

On the other hand, by making the content of the Na ₂ O component 20.0% or less, the decrease in the refractive index can be suppressed, the chemical durability can hardly decrease, and the devitrification caused by the excessive content can be reduced.

Therefore, the content of the _Na2O component is preferably 20.0% or less, more preferably 15.0% or less, more preferably 13.0% or less, more preferably less than 10.0%, more preferably less than 8.0% .

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

The B ₂ O ₃ component is an arbitrary component that, when the content exceeds 0%, promotes stable glass formation and lowers the liquidus temperature, thereby improving devitrification resistance and improving the meltability of glass raw materials. Therefore, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably more than 0.1%, more preferably more than 1.0%, more preferably more than 3.0%, and more preferably more than 3.0%. Greater than 5.0%. In particular, from the viewpoint of forming molten glass at low temperature, improving devitrification resistance, and reducing streaks, the _B2O3 content is preferably _3.0 % or more, more preferably 5.0% or more, and more preferably 5.0% or more. 7.0% or more.

On the other hand, by making the content of the B ₂ O ₃ component 20.0% or less, a decrease in the refractive index can be suppressed and an increase in the partial dispersion ratio can be suppressed. In addition, reduction in chemical durability of glass can be improved. Therefore, the content _of the _B2O3 component is preferably 20.0% as the upper limit, more preferably 18.0% as the upper limit, more preferably 15.0% as the upper limit, and more preferably 12.0% as the upper limit. upper limit.

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 TiO ₂ component is an optional component that can increase the refractive index, lower the Abbe number, and improve devitrification resistance when the content exceeds 0%.

On the other hand, by reducing the content of the _TiO2 component to 15.0% or less, the coloring of the glass can be reduced and the internal transmittance can be improved. In addition, this makes it difficult to increase the partial dispersion ratio, so that a desired low partial dispersion ratio close to the standard line can be obtained relatively easily. Therefore, the content of the _TiO2 component is preferably 15.0% or less, more preferably 10.0% or less, more preferably 5.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, More preferably, it is 2.0% or less, and more preferably, it is less than 1.0%. In particular, it is preferable not to actually contain it from the viewpoint of reducing the abnormal dispersion of glass.

TiO ₂ component, TiO ₂ etc. can be used as a raw material.

The MgO component is an arbitrary component that can lower the melting temperature of glass when the content exceeds 0%.

On the other hand, by making the content of the MgO component 10.0% or less, the decrease in the refractive index can be suppressed, and devitrification can be reduced. Therefore, the content of the MgO component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

As the MgO component, MgO, MgCO ₃ , MgF ₂ and the like can be used as a raw material.

The CaO component is an optional component that can reduce the material cost of the glass, reduce the Abbe number and devitrification, and improve the meltability of the glass raw material when the content exceeds 0%. Therefore, the content of the CaO component is more preferably greater than 0%, more preferably greater than 1.0%, and more preferably greater than 2.0%.

On the other hand, by making the content of the CaO component 10.0% or less, the decrease in the refractive index, the increase in the Abbe number, and the increase in the partial dispersion ratio can be suppressed, and devitrification can be reduced. Therefore, the content of the CaO component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

As the CaO component, CaCO ₃ , CaF ₂ , etc. can be used as a raw material.

The SrO component is an optional component that can increase the refractive index and improve devitrification resistance when the content exceeds 0%.

In particular, by making the content of the SrO component 10.0% or less, it is possible to suppress a decrease in chemical durability. Therefore, the content of the SrO component is preferably 10.0% or less, more preferably less than 5.0%, more preferably 3.0% or less, still more preferably less than 3.0%, still more preferably less than 1.0%.

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

The BaO component is a material that can increase the refractive index and reduce the partial dispersion ratio when the content exceeds 0%, and can improve the devitrification resistance and the melting property of the glass raw material, and can reduce the glass material compared with other alkaline earth metal components. Any component of the cost.

In particular, by making the content of the BaO component 10.0% or less, the decrease in the refractive index, the increase in the Abbe's number, and the increase in the partial dispersion ratio can be suppressed, and devitrification can be reduced. Therefore, the content of the BaO component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

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

The La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are any of the components that can increase the refractive index and reduce the partial dispersion ratio when the content of at least one of them exceeds 0%. Element.

In particular, by setting the respective contents of the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component to 10.0% or less, an increase in the Abbe number can be suppressed, devitrification can be reduced, and the Reduce material costs. Therefore, the respective contents of La ₂ O ₃ components, Gd ₂ O ₃ components, Y ₂ O ₃ components, and Yb ₂ O ₃ components are preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, More preferably, the upper limit is 3.0%, and more preferably, it is less than 1.0%.

La ₂ O ₃ components, Gd ₂ O ₃ components, Y ₂ O ₃ components, and Yb ₂ O ₃ components can be used as raw materials La ₂ O ₃ , La(NO ₃ ) ₃ ·XH ₂ O (X is an arbitrary integer), Y ₂ O ₃ , YF ₃ , Gd ₂ O ₃ , GdF ₃ , Yb ₂ O ₃ , etc.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index, lower the Abbe number and the partial dispersion ratio, and improve devitrification resistance when the content exceeds 0%.

_On the other hand, by keeping the content of the _Ta2O5 component below 10.0 _% , the usage amount of the rare mineral resource _Ta2O5 component can be reduced, and the glass can be easily melted at a lower temperature, so the production cost of the glass can be reduced. In addition, it is possible to reduce the devitrification of the glass caused by the excessive content of the Ta ₂ O ₅ component. Therefore, the content of the Ta ₂ O ₅ component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%. In particular, from the viewpoint of reducing the material cost of the glass, the Ta ₂ O ₅ component may not be contained.

As a _Ta2O5 component, _{Ta2O5 etc.} can be used as a raw _material .

The WO ₃ component is an arbitrary component that can increase the refractive index, lower the Abbe number, improve the devitrification resistance, and improve the meltability of the glass raw material when the content exceeds 0%.

On the other hand, by making the content of the WO ₃ component 10.0% or less, the partial dispersion ratio of the glass can hardly be increased, and the coloring of the glass can be reduced and the internal transmittance can be improved. Therefore, the content of the WO ₃ component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

As a WO ₃ component, WO ₃ etc. can be used as a raw material.

The P ₂ O ₅ component is an optional component that can improve the stability of the glass when the content exceeds 0%.

On the other hand, by making the content of the P ₂ O ₅ component 10.0% or less, devitrification due to an excessive content of the P ₂ O ₅ component can be reduced. Therefore, the content of the P ₂ O ₅ component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 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 , etc. can be used as raw materials.

The GeO ₂ component is an optional component that can increase the refractive index and reduce devitrification when the content exceeds 0%.

On the other hand, by making the content of the GeO ₂ component 10.0% or less, the amount of the relatively expensive GeO ₂ component used can be reduced, and thus the material cost of the glass can be reduced. Therefore, the content of the GeO ₂ component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

As a _GeO2 component, _GeO2 etc. can be used as a raw material.

Al ₂ O ₃ components and Ga ₂ O ₃ components are optional components that can improve chemical durability and also improve devitrification resistance when the content of at least one of them exceeds 0%.

On the other hand, by making the respective contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 10.0% or less, devitrification caused by too much content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component can be reduced. Therefore, the respective contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component are preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and still more preferably less than 1.0%. .

For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga(OH) ₃ , and the like can be used as raw materials.

The Bi ₂ O ₃ component is an arbitrary component that can increase the refractive index, lower the Abbe number, and lower the glass transition temperature when the content exceeds 0%.

On the other hand, by making the content of the Bi ₂ O ₃ component 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio, reduce the coloring of the glass, and improve the internal transmittance. Therefore, the content of the Bi ₂ O ₃ component is more preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%.

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

The TeO ₂ component is an arbitrary component that can increase the refractive index, lower the partial dispersion ratio, and lower the glass transition temperature when the content exceeds 0%.

On the other hand, by reducing the content of the TeO ₂ component to 5.0% or less, the coloring of the glass can be reduced and the internal transmittance can be improved. In addition, by reducing the use of the more expensive _TeO2 component, a glass with a lower material cost can be obtained. Therefore, the content of the TeO ₂ component is preferably 5.0% or less, more preferably less than 3.0%, and still more preferably less than 1.0%.

TeO ₂ component, TeO ₂ etc. can be used as a raw material.

The SnO ₂ component is an arbitrary component that can clear (defoam) molten glass and improve the visible light transmittance of the glass when the content exceeds 0%.

On the other hand, by making the content of the SnO ₂ component 1.0% or less, the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass can hardly occur. In addition, since the alloying of the _SnO2 component with the melting equipment (especially precious metals such as Pt) can be reduced, a longer service life of the melting equipment can be achieved. Therefore, the content of the SnO ₂ component is preferably 1.0% or less, more preferably less than 0.5%, and still more preferably less than 0.1%.

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

The Sb ₂ O ₃ component is a component that promotes degassing of the glass and makes the glass clear when the content exceeds 0%, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ components, by making the content of 1.0% or less relative to the total mass of the glass, excessive foaming during glass melting can be prevented, and the Sb ₂ O ₃ components can be mixed with melting equipment (especially precious metals such as Pt) Alloying is difficult to occur. Therefore, the content rate of the Sb ₂ O ₃ component with respect to the total mass of the glass of the composition in terms of oxides is preferably 1.0%, more preferably 0.8%, and still more preferably 0.6%. is the upper limit. Here, especially from the viewpoint of easily obtaining optical glass with low negative effect, the content of the Sb ₂ O ₃ component in the total mass of the glass in terms of oxide composition is preferably 0.5% as the upper limit, more preferably 0.5%. The upper limit is preferably 0.3%, more preferably 0.1%.

In addition, the component for clearing and defoaming glass is not limited to the above-mentioned Sb ₂ O ₃ component, and clarifiers and defoaming agents widely known in the field of glass production, or combinations thereof may be used.

The ratio of the sum of the contents of the Li ₂ O component and the K ₂ O component to the sum of the contents of the ZrO ₂ component and the Li ₂ O component is preferably greater than 0 and less than 2.5.

In particular, by making this mass ratio larger than 0, devitrification and transmittance can be improved.

Therefore, the lower limit of (Li ₂ O+K ₂ O)/(ZrO ₂ +Li ₂ O) is preferably greater than 0%, more preferably greater than 0.1%, and still more preferably greater than 0.3%.

On the other hand, by making this mass ratio less than 2.5, the abnormal dispersion of the glass can be reduced while maintaining the refractive index of the glass. Therefore, the upper limit of (Li ₂ O+K ₂ O)/(ZrO ₂ +Li ₂ O) is preferably less than 2.5, more preferably less than 2.1, more preferably less than 2.0, and more preferably It is less than 1.5, more ideally less than 1.0, more ideally less than 0.5.

The total amount (sum of mass) of the SiO ₂ component and the Nb ₂ O ₅ component is more than 50.0%. Accordingly, it is possible to obtain a glass having good formability, good chemical durability, small abnormal dispersion, and a constant viscosity.

Therefore, the sum of the masses is preferably greater than 50.0%, more preferably not less than 53.0%, more preferably not less than 54.0%, and more preferably not less than 58.0%.

On the other hand, the sum of the masses is preferably 90.0% or less, more preferably less than 85.0%, more preferably less than 81.0%, and more preferably less than 76.0%.

The sum of contents (sum of mass) of Ln ₂ O ₃ components (where Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 15.0% or less. Accordingly, devitrification of the glass can be reduced, an increase in the Abbe number can be suppressed, and the material cost of the glass can be reduced. Therefore, the sum of the mass of Ln ₂ O ₃ components is preferably 15.0% or less, more preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 3.5%.

By making the sum of the contents (sum of mass) of _Rn2O components (wherein, Rn is one or more selected from the group consisting of Li, Na, and K) greater than 0%, the meltability of the glass raw material can be improved, And lower the glass transition temperature. Therefore, the content of the _Rn2O component is preferably more than 0%, more preferably at least 5.0%, more preferably at least 5.0%, more preferably at least 8.0%, and more preferably at least 10.0%. , more ideally greater than 10.0%, more ideally greater than 12.0%, more ideally greater than 13.0%.

On the other hand, the sum of contents (sum of mass) of Rn ₂ O components (where Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 30.0% or less. According to this, it is possible to make it difficult to lower the refractive index of the glass, and it is possible to reduce devitrification when forming the glass. In addition, moldability can be improved by increasing the viscosity in glass. Therefore, the total content of Rn ₂ O components is preferably 30.0% as the upper limit, more preferably 25.0% as the upper limit, more preferably 20.0% as the upper limit, and more preferably 17.0% as the upper limit. upper limit.

The total content (sum of mass) of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 30.0% or less. Accordingly, devitrification of glass caused by excessive content of these components can be reduced. Therefore, the mass sum of the RO components is preferably 30.0% or less, more preferably 25.0% or less, more preferably 20.0% or less, more preferably 15.0% or less, more preferably less than 10.0% , more ideally less than 5.0%.

On the other hand, the sum of the mass of the RO components is preferably greater than 0%, more preferably 1.0% or more, and more preferably Above 2.0%.

<About ingredients that should not be contained>

Next, components that should not be contained in the optical glass of the present invention and components that should not be contained will be described.

Other components may be added as needed within the range not impairing the properties of the glass of the invention of the present application. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, various transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo have Glass can be colored even if a small amount of each component is contained alone or mixed, and has the property of absorbing a specific wavelength in the visible region, so it is preferable not to actually contain it, especially in optical glasses using wavelengths in the visible region.

In addition, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with a high environmental burden, it is preferable not to actually contain them, that is, it is preferable not to contain them at all except for unavoidable contamination.

In addition, each component of Th, Cd, Tl, Os, Be, and Se has tended to limit its use as a harmful chemical substance in recent years. Environmental protection measures are required. Therefore, when paying attention to the influence on the environment, it is preferable not to contain these components actually.

[Production method]

The optical glass of the present invention is produced, for example, as follows. That is to say, in order to uniformly mix the above-mentioned raw materials so that each component is within a specified content range, the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible for pre-melting, and then put into a gold crucible, a platinum crucible, or a platinum crucible. Crucible, platinum alloy crucible or iridium crucible and melted in the temperature range of 1000-1400 °C for 3-5 hours, uniformly stirred and defoaming, etc., and then the temperature was lowered to 900-1100 °C and finally stirred to remove streaks, It is poured into molds and allowed to cool slowly.

<Physical properties>

The optical glass of the present invention has a high refractive index and an Abbe number within a predetermined range.

The lower limit of the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.60, more preferably 1.63, and still more preferably 1.65. The upper limit of the refractive index is preferably 1.78, more preferably 1.77, more preferably 1.76, more preferably 1.75, and more preferably 1.73. , it is more ideal to use 1.70 as the upper limit.

The Abbe number (ν _d ) of the optical glass of the present invention preferably takes 28 as the lower limit, more preferably takes 29 as the lower limit, more preferably takes 30 as the lower limit, and more preferably takes 31 as the lower limit. The lower limit is more ideally 33 as the lower limit. On the other hand, the Abbe number (ν _d ) of the optical glass of the present invention is more preferably 47 as the upper limit, more preferably 45 as the upper limit, more preferably 43 as the upper limit, and more preferably Use 42 as the upper limit, more preferably 41 as the upper limit, and more preferably 40 as the upper limit.

The optical glass of the present invention having such a refractive index and Abbe number is useful for optical design, and in particular, not only can realize high imaging characteristics and miniaturization of an optical system, but also can expand the degree of freedom of optical design.

The optical glass of the present invention has a relatively low partial dispersion ratio (θg, F).

More specifically, the partial dispersion ratio (θg, F) and Abbe number (ν _d ) of the optical glass of the present invention satisfy (-0.00256×ν _d +0.637)≦(θg, F)≦(-0.00256×ν _d +0.684) is better.

Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) are more ideal to satisfy the relationship of θg, F≧(-0.00256×ν _d +0.637), and more It is ideal to satisfy the relationship of θg, F≧(-0.00256×ν _d +0.647), and more ideally to satisfy the relationship of θg, F≧(-0.00256×ν _d +0.657).

On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) ideally satisfy the relationship of θg, F≦(-0.00256×ν _d +0.684), It is more desirable to satisfy the relationship of θg, F≦(-0.00256×ν _d +0.681), and it is more desirable to satisfy the relationship of θg, F≦(-0.00256×ν _d +0.677).

According to this, since an optical glass having a lower partial dispersion ratio (θg, F) can be obtained, an optical element formed of the optical glass can contribute to reducing the chromatic aberration of the optical system.

In addition, especially in the region where Abbe's number (ν _d ) is small, the partial dispersion ratio (θg, F) of ordinary glass is higher than the standard line. Taking Abbe's number (ν _d ) as the horizontal axis, When the partial dispersion ratio (θg, F) is the vertical axis, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of ordinary glass can be expressed by a curve whose slope is larger than the standard line. In the relational expression of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) mentioned above, by specifying these relations using a straight line whose inclination is larger than the standard line, it is shown that the partial dispersion ratio ( θg, F) Smaller glasses.

In the present invention, the surface weather resistance is preferably grade 1 or grade 2, more preferably grade 1. Here, the surface weather resistance was measured by using the following test method.

As a test piece, a sample with a polished surface of 30mm×30mm×3mm was used, exposed for 96 hours in a constant temperature and humidity tank with a temperature of 60°C and a relative humidity of 95%, and then observed the polished surface with a microscope of 50 times and observed mold. spotty state. The criterion for judging is that when the sample after the 96-hour test is observed under an illumination of 1500 lux, no mildew spots are observed at all, and the sample is rated as grade 1, and no mildew spots are observed when observed under 100 lux, but in the Samples with mold stains observed at 1500 lux were rated as grade 2, and samples with mildew spots observed at 100 lux were rated as grade 3. In addition, for grade 3 samples, re-expose them in a constant temperature and humidity chamber with a temperature of 50°C and a relative humidity of 85% for 6 hours, then observe the polished surface with a 50 times microscope, and observe mildew spots at 1500 lux The sample is rated as level 4. The samples with no mildew spots are still rated as grade 3.

In addition, in this specification, "surface weather resistance" means, for example, when used as a lens preform material for a long period of time, depending on the storage environment of the optical glass, the quality of the mildew state when exposed for a certain period of time.

The optical glass of the present invention is preferably less colored.

In particular, the optical glass of the present invention, if represented by the transmittance of the glass, shows a wavelength (λ ₈₀ ) of 80% of the spectral transmittance in a sample with a thickness of 10 mm, preferably 420 nm or less, more preferably Below 400nm, more preferably below 380nm.

In addition, the optical glass of the present invention has a spectral transmittance of 5% of the wavelength (λ ₅ ) in a sample with a thickness of 10 mm, preferably 365 nm or less, more preferably 345 nm or less, more preferably 330 nm or less.

Accordingly, the absorption end of the glass is located near the ultraviolet region, which improves the transparency of the glass in the visible light region, so the optical glass can be preferably used as a material for optical elements such as lenses.

In addition, the optical glass of the present invention is required to have high resistance to devitrification. According to this, it is possible to suppress a decrease in transmittance due to crystallization of the glass during glass production, and thus the optical glass can be suitably applied to optical elements such as lenses that transmit visible light. In particular, the optical glass of the present invention preferably has a relatively low liquidus temperature of 1200°C or lower. More specifically, the liquidus temperature of the optical glass of the present invention is preferably 1200°C as the upper limit, more preferably 1150°C as the upper limit, more preferably 1100°C as the upper limit, and more preferably The upper limit is 1050°C. According to this, even if the molten glass flows out at a lower temperature, since the degree of crystallization of the produced glass is reduced, the devitrification resistance when forming the glass from the molten state can be improved, and the optical damage to the optical element using the glass can be reduced. The influence of characteristics. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 500°C or higher, specifically 550°C or higher, more specifically It is said that it is mostly above 600°C. In addition, the "liquidus temperature" in this specification refers to placing a granular glass sample crushed to a diameter of about 2mm on a platinum plate, keeping it in a furnace with a temperature gradient of 800°C to 1220°C for 30 minutes, and then taking it out. , measured by observing the presence or absence of crystals in the glass with a microscope with a magnification of 80 times after cooling, the lowest temperature at which no crystals are found in the glass and devitrification does not occur.

[Preforms and Optical Components]

Based on the produced optical glass, a glass molded body can be produced by using compression molding methods such as reheat press molding and precision press molding. That is, it is possible to manufacture a preform for press molding from optical glass, perform reheat press molding on the preform, and then perform polishing treatment to produce a glass molded body, or for example, fine press a preform produced by performing polishing treatment. Molding produces a glass molded body. In addition, the method of manufacturing a glass molding is not limited to these methods.

The glass molded article produced in this way is useful for various optical elements, and it is particularly preferable for use in optical elements such as lenses and prisms. According to this, in the transmitted light of the optical system provided with the optical element, color fringing due to chromatic aberration can be reduced. Therefore, when the optical element is applied to a camera, a subject can be represented more accurately, and when the optical element is applied to a projector, a desired image can be projected with higher definition.

【Example】

In Tables 1 to 12, examples (No.A1 to No.A28, No.B1 to No.B52, No.C1 to No.C3) and comparative examples (No.a, No.b) of the present invention are shown. ), and refractive index ( _nd ), Abbe number (ν _d ), partial dispersion ratio (θg, F), spectral transmittance showing 5% and 80% wavelength (λ ₅ , λ ₈₀ ), liquid phase Temperature, surface weatherability results. Here, the embodiments (No.A1～No.A28, No.C1～No.C3) can be used as the embodiments of the first optical glass, and the embodiments (No.B1～No.B52, No.C1～No.C3 ) can also be used as an embodiment of the second optical glass. In addition, the following embodiments are always for the purpose of illustration and are not limited to these embodiments.

The glasses of Examples and Comparative Examples are selected from ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphoric acid compounds corresponding to the raw materials of each component. The high-purity raw materials are weighed and uniformly mixed with the composition ratios of each embodiment and comparative example shown in the table, and then dropped into a quartz crucible (platinum crucibles and aluminum crucibles can also be used according to the melting properties of the glass), and According to the melting difficulty of the glass composition, it is melted in an electric furnace at a temperature range of 1100°C to 1400°C for 0.5 to 5 hours, then transferred to a platinum crucible, stirred evenly and defoamed, etc., and the temperature is lowered to 1000 to 1400°C. Stir well, then pour into molds and let cool slowly, creating glass.

The refractive index (n _d ), Abbe number (ν _d ) and partial dispersion ratio (θg, F) of the glasses of Examples and Comparative Examples were measured in accordance with JOGIS01-2003 of Japan Optical Glass Industry Association Standard.

In addition, as the glass used in this measurement, what was treated with the annealing furnace was used at the slow cooling rate of -25 degreeC/hr.

The surface weather resistance of Examples and Comparative Examples was evaluated by the following method.

As a test piece, a sample with a polished surface of 30mm×30mm×3mm was used, exposed for 96 hours in a constant temperature and humidity tank with a temperature of 60°C and a relative humidity of 95%, and then observed the polished surface with a microscope of 50 times and observed mold. spotty state. The criterion for judging is that when the sample after the 96-hour test is observed under an illumination of 1500 lux, no mildew stains are observed at all. Samples with mildew stains observed at 1500 lux are defined as grade 2, and samples with mildew stains observed at 100 lux are defined as grade 3. In addition, for grade 3 samples, re-expose them in a constant temperature and humidity chamber with a temperature of 50°C and a relative humidity of 85% for 6 hours, then observe the polished surface with a 50 times microscope, and observe mildew spots at 1500 lux The sample is specified as level 4. The samples without mildew stains are still rated as grade 3.

The transmittance of the glasses of Examples and Comparative Examples was measured in accordance with JOGIS02 standard of Japan Optical Glass Industry Association. In addition, in the present invention, by measuring the transmittance of the glass, whether the glass is colored or not and its degree are obtained. Specifically, for a relatively parallel polished product with a thickness of 10 ± 0.1 mm, according to JISZ8722, the spectral transmittance of 200 to 800 nm is measured, and λ ₅ (the wavelength when the transmittance is 5%) and λ ₈₀ (the wavelength when the transmittance is 80%) are obtained. wavelength).

For the liquidus temperature of Examples and Comparative Examples, crushed glass samples were placed on a platinum plate at intervals of 10 mm, kept in a furnace with a temperature gradient from 800°C to 1200°C for 30 minutes, taken out, cooled and passed through The measurement was performed by observing the presence or absence of crystals in the glass sample using a microscope with a magnification of 80 times. At this time, as a sample, the optical glass was pulverized into particles having a diameter of about 2 mm.

Table 1

Table 2

table 3

Table 4

table 5

Table 6

Table 7

Table 8

Table 9

Table 10

Table 11

Table 12

As shown in these tables, in the optical glass of the examples of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) satisfy (-0.00256×ν _d +0.637)≦(θg, F)≦(- 0.00256×ν _d +0.684), more specifically, the relationship of (-0.00256×ν _d +0.657)≦(θg, F)≦(-0.00256×ν _d +0.679) is satisfied. In particular, the optical glasses of Examples (No.B1～No.B52, No.C1～No.C3) satisfy (-0.00256×ν _d +0.657)≦(θg, F)≦(-0.00256×ν _d +0.677 )Relationship. Here, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the glass of the embodiment of the present application is shown in FIG. 2 .

In the optical glass of the embodiment of the present invention, the refractive index ( _nd ) is above 1.60, more specifically above 1.65, and the refractive index ( _nd ) is below 1.78, more specifically below 1.76. within the required range. In particular, the optical glasses of Examples (No.A1 to No.A28, No.C1 to No.C3) have a refractive index ( _nd ) of 1.75 or less, more specifically, 1.73 or less.

In addition, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) of 28 or more, more specifically 30 or more, that is, within the required range. In addition, the optical glass of the example of the present invention has an Abbe number (ν _d ) of 47 or less, more specifically, 46 or less, which is within the required range. In particular, the optical glasses of Examples (No.A1 to No.A28, No.C1 to No.C3) have an Abbe number (ν _d ) of 43 or less.

In addition, in the optical glasses of the examples of the present invention, λ ₈₀ (the wavelength at which the transmittance is 80%) is all 420 nm or less, more specifically 400 nm or less. In particular, the optical glass of the Examples (No.A1 to No.A28, No.C1 to No.C3) had λ ₈₀ (wavelength at 80% transmittance) of 390 nm or less.

In addition, in the optical glasses of the examples of the present invention, λ ₅ (wavelength at 5% transmittance) is 365 nm or less, more specifically 345 nm or less, more specifically 340 nm or less. In particular, in the optical glasses of Examples (No.A1 to No.A28, No.C1 to No.C3), λ ₅ (wavelength at 5% transmittance) is 335 nm or less.

Therefore, it became clear that the optical glass of the Example of this invention has high transmittance|permeability to visible light and is hard to be colored.

In addition, the optical glass of the examples (No.A1 to No.A28, No.C1 to No.C3) of the present invention has a liquidus temperature of 1200°C or lower, more specifically 1110°C or lower, more specifically It is below 1050°C. Therefore, these optical glasses are less prone to devitrification and opalescence due to reheating, and therefore have high reheat press formability.

Moreover, the optical glass of the Example (No.B1-No.B52, No.C1-No.C3) of this invention has a surface weather resistance of 1st class.

Therefore, it can be clarified that these optical glasses are optical glasses whose surfaces have good weather resistance and are less prone to so-called mildew stains.

Moreover, using the optical glass of the Example of this invention, the glass block was formed, and this glass block was ground and polished, and it processed into the shape of a lens and a preform. As a result, various lenses and preform shapes can be stably processed.

In addition, the optical glass described in Comparative Example (No.b) satisfies the required optical constants ( _nd , _νd ), but due to the high partial dispersion ratio, the abnormal dispersion is small and the transmittance and chemical durability Therefore, the refractive index (n _d ) and Abbe number (ν _d ), which are the object of the present invention, cannot be obtained within the required range, and the partial dispersion ratio (θg, F) is small and the surface weather resistance Good optical glass.

Above, the present invention has been specifically described for the purpose of example, but this embodiment is only for the purpose of example all the time, it should be understood that, without departing from the spirit and scope of the present invention, those skilled in the art can carry out various kind of change.

Claims (12)

1. An optical glass, characterized in that, calculated by mass % of the composition in terms of oxides, Contains 20.0 to 60.0% of SiO ₂ components, Nb ₂ O ₅ composition 10.0～50.0%, Furthermore, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) satisfy the relationship of (-0.00256×ν _d +0.637)≦(θg, F)≦(-0.00256×ν _d +0.684). 2 . The optical glass according to claim 1 , which contains 0 to 20.0% of a ZrO ₂ component in terms of mass % of the composition in terms of oxides. 3 . 3. The optical glass according to claim 1 or ₂ , which contains 0 to 15.0% of a K2O component in terms of mass % of the composition in terms of oxides. 4. The optical glass according to any one of claims 1 to 3, characterized in that the surface weather resistance grade is grade 1 or grade 2. 5. The optical glass according to any one of claims 1 to 4, characterized in that, Calculated by mass% of the composition in terms of oxides, The ZnO composition is 0-25.0%, The Li ₂ O composition is 0 to 20.0%, The Na ₂ O component is 0-20.0%, The B ₂ O ₃ component is 0 to 20.0%, The _TiO2 composition is 0 to 15.0%, MgO composition is 0-10.0%, CaO composition is 0-10.0%, The SrO composition is 0-10.0%, The BaO composition is 0-10.0%, La ₂ O ₃ composition is 0-10.0%, The Gd ₂ O ₃ composition is 0 to 10.0%, The Y ₂ O ₃ composition is 0 to 10.0%, Yb ₂ O ₃ composition is 0-10.0%, The composition of _Ta2O5 is _0-10.0 %, The WO ₃ component is 0 to 10.0%, The P ₂ O ₅ composition is 0 to 10.0%, The composition of _GeO2 is 0~10.0%, Al ₂ O ₃ composition is 0-10.0%, The Ga ₂ O ₃ composition is 0 to 10.0%, The composition of Bi ₂ O ₃ is 0-10.0%, The TeO2 composition is ₀ to 5.0%, _SnO2 composition is 0~5.0%, The Sb ₂ O ₃ component is 0 to 1.0%. 6 . The optical glass according to claim 1 , wherein the mass ratio (Li ₂ O+K ₂ O)/(ZrO ₂ +Li ₂ O) is greater than 0 to less than 2.5. 7. The optical glass according to any one of claims 1 to 6, characterized in that the sum of the contents of SiO ₂ and Nb ₂ O ₅ is greater than 50.0%. 8. The optical glass according to any one of claims 1 to 7, characterized in that, Calculated in standard mass % of oxides, The sum of the mass of Ln ₂ O ₃ components is 0 to 15.0%. In the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb, The sum of the mass of the RO components is 0 to 30.0%. In the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba, The sum of the mass of the Rn ₂ O components is 0 to 30.0%. In the formula, Rn is one or more selected from the group consisting of Li, Na, and K. 9 . The optical glass according to claim 1 , which has a refractive index ( _{nd ) of 1.60 to 1.78 and an Abbe number (ν d )} of 28 to 47. 10. The optical glass according to any one of claims 1 to 9, characterized in that the wavelength (λ ₈₀ ) at which the spectral transmittance shows 80% is below 420 nm, and the wavelength (λ ₅ ) at which the spectral transmittance shows 5% below 365nm. 11. A preform for grinding and/or precision stamping, comprising the optical glass according to any one of claims 1 to 10. 12. An optical element comprising the optical glass according to any one of claims 1 to 10.