WO2010038597A1 - Optical glass and method for suppressing the deterioration of spectral transmittance - Google Patents

Abstract

Provided are an optical glass which retains high spectral transmittance even after the lapse of a long time and a method for suppressing the deterioration of optical transmittance of glass.  The optical glass has a content of Sb₂O₃ components of 0.5mass% or lower relative to the whole mass of the glass in terms of oxide and a solarization (a deterioration in spectral transmittance at a wavelength of 450nm) of 5.0% or below.  The method for suppressing the deterioration of optical transmittance of glass comprises reducing the content of Sb₂O₃ components in glass.

Description

Optical glass and method for suppressing deterioration of spectral transmittance

The present invention relates to optical glass and a method for suppressing deterioration of spectral transmittance.

In recent years, the digitization and high definition of devices that use optical systems are rapidly progressing. For optical elements such as spherical lenses used in various optical devices such as digital cameras and video cameras. Accordingly, there is an increasing demand for higher accuracy, lighter weight, and smaller size.

Such optical elements can be produced by grinding and polishing molded glass obtained by heating and softening a glass material (reheat press molding), or by grinding and polishing a gob or glass block. A method (precise press molding) is used in which a material or a preform material formed by known flotation molding is heat-softened and pressure-molded with a mold having a highly accurate molding surface.

As glass used for such reheat press molding and precision press molding, an optical glass containing an SiO ₂ component and an Nb ₂ O ₅ component and / or a TiO ₂ component is known. As such an optical glass, a glass having a composition represented by Patent Documents 1 and 2 is known. For example, Patent Document 1 discloses an optical glass having a refractive index (n _d ) of 1.63 to 1.75 and an Abbe number (ν _d ) of 23 to 35. Further, Patent Document 2 discloses an optical glass having a refractive index (n _d ) of 1.80 or more and an Abbe number (ν _d ) of 30 or less.

Japanese Patent Laid-Open No. 2002-087841 Japanese Patent Laid-Open No. 2004-155639

However, the glasses disclosed in Patent Documents 1 and 2 have a problem of solarization in which the spectral transmittance is reduced by ultraviolet rays contained in sunlight or the like. Since the glass having a large solarization is colored by being irradiated with ultraviolet rays for a long time, it has been difficult to maintain a desired spectral transmittance at the beginning of manufacture.

The object of the present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide an optical glass and a method for suppressing deterioration of spectral transmittance in which deterioration of spectral transmittance with time is suppressed. There is to get.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies, and as a result, the content of the Sb ₂ O ₃ component contained in the optical glass is reduced, and more preferably Pt mixed in the optical glass. By adjusting the content of the component and / or Fe component, it was found that solarization of the optical glass was reduced, and the present invention was completed. Specifically, the present invention provides the following.

(1) The content of the Sb ₂ O ₃ component is 0.5% or less by mass% with respect to the total glass mass of the oxide equivalent composition, and solarization (amount of degradation of spectral transmittance at a wavelength of 450 nm) is 5. Optical glass that is 0% or less.

(2) The optical glass according to (1), wherein the content of the Pt component is 15 ppm or less.

(3) The optical glass according to (1) or (2), wherein the content of Fe component is 50 ppm or less with respect to the total mass of the glass having an oxide equivalent composition.

(4) The optical glass according to any one of (1) to (3), which contains a SiO ₂ component, a Nb ₂ O ₅ component, and / or a TiO ₂ component.

(5) 1.0% or more and 60.0% or less of SiO ₂ component and 10.0% or more and 65.0% or less of Nb ₂ O ₅ component in mass% with respect to the total glass mass of oxide conversion composition. The optical glass according to (4), wherein the content of the TiO ₂ component is 40.0% or less.

(6) 0 to 40.0% of B ₂ O ₃ component and / or 0 to 30.0% of GeO ₂ component and / or Al ₂ O _{3 in} mass% with respect to the total glass mass of the oxide equivalent composition Component 0-15.0%, and / or ZrO ₂ component 0-20.0%, and / or Ta ₂ O ₅ component 0-20.0%, and / or WO ₃ component 0-20.0%, and And / or ZnO component 0-30.0%, and / or MgO component 0-20.0%, and / or CaO component 0-30.0%, and / or SrO component 0-30.0%, and / or BaO component 0-30.0%, and / or Li ₂ O component 0-20.0%, and / or Na ₂ O component 0-30.0%, and / or K ₂ O component 0-20.0%
The optical glass according to any one of (1) to (5), further comprising:

(7) La ₂ O ₃ component 0 to 50.0% and / or Gd ₂ O ₃ component 0 to 30.0% and / or Y _{2 in} mass% with respect to the total glass mass of the oxide equivalent composition. O ₃ component 0-30.0%, and / or Ga ₂ O ₃ component 0-20.0%, and / or TeO ₂ component 0-50.0%, and / or Bi ₂ O ₃ component 0-50. 0% and / or CeO ₂ component 0-10.0%
The optical glass according to any one of (1) to (6), further containing each component of

(8) (−1.60 × 10 ⁻³ × ν _d +0.6346) ≦ (θg, F) when the partial dispersion ratio (θg, F) is in the range of ν _d ≦ 25 with the Abbe number (ν _d ) F) ≦ (−4.21 × 10 ⁻³ × ν _d +0.7207), and in the range of ν _d > 25, (−2.50 × 10 ⁻³ × ν _d +0.6571) ≦ (θg , F) ≦ (−4.21 × 10 ⁻³ × ν _d +0.7207), the optical glass according to any one of (1) to (7).

(9) The optical glass according to any one of (1) to (8), which has a glass transition point (Tg) of 400 ° C. or higher and 650 ° C. or lower.

(10) An optical element using the optical glass according to any one of (1) to (9) as a base material.

(11) A lens preform made of the optical glass according to any one of (1) to (9).

(12) A lens preform for mold press molding made of the optical glass according to any one of (1) to (9).

(13) An optical element formed by molding the lens preform described in (11) or (12).

(14) A method for suppressing degradation of spectral transmittance of glass, the method for suppressing degradation of spectral transmittance, which reduces the content of Sb ₂ O ₃ component contained in glass.

According to the present invention, by reducing the content of Sb ₂ O ₃ component contained in the optical glass, more preferably by adjusting the content of Pt component and / or Fe component mixed in the optical glass, It is possible to obtain an optical glass in which the solarization of the optical glass due to long-time irradiation is reduced and a method for suppressing the deterioration of spectral transmittance.

Is a diagram showing an sb ₂ O ₃ components of content and solarization relationship. In each Sb ₂ O ₃ ingredient content is a diagram showing the relationship between content and solarization of Pt component. It is a figure which shows the relationship between content of Fe component, and solarization.

In the optical glass of the present invention, the content of Sb ₂ O ₃ component is 0.5% or less by mass% with respect to the total mass of the glass having an oxide equivalent composition, and solarization (amount of degradation of spectral transmittance at a wavelength of 450 nm). ) Is 5.0% or less. By reducing the content of the Sb ₂ O ₃ component contained in the optical glass, solarization of the glass is reduced. For this reason, the optical glass and the optical element in which deterioration with time of the spectral transmittance is suppressed can be obtained.

Furthermore, degradation suppression method of the spectral transmittance of the glass of the present invention is to reduce the content of Sb ₂ O ₃ component contained in the glass. By reducing the content of the Sb ₂ O ₃ component contained in the glass, solarization of the optical glass is reduced. For this reason, it is possible to more reliably produce a lens preform or an optical element in which deterioration of the spectral transmittance over time is suppressed.

Hereinafter, embodiments of the optical glass and the spectral transmittance degradation suppressing method of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and is within the scope of the object of the present invention. However, it can implement by changing suitably. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Optical glass]
First, components and physical properties of the optical glass of the present invention will be described. The glass used in the spectral transmittance deterioration suppressing method of the present invention is not particularly limited as long as the content of the Sb ₂ O ₃ component is not more than a predetermined glass, but among them, optical glass as described below is used. Preferably there is.

Hereinafter, the composition range of each component constituting the optical glass of the present invention will be described below. In the present specification, unless otherwise specified, the contents of the respective components are all expressed in mass% with respect to the total glass mass of the oxide conversion composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. The composition represents each component contained in the glass, with the total mass of the generated oxide being 100% by mass.

<Ingredients whose content should be suppressed>
First, the component which should suppress content in the optical glass of this invention is demonstrated.

The Sb ₂ O ₃ component is a component having a defoaming effect when the glass is melted, but it contributes to the enhancement of solarization of the optical glass by irradiation with ultraviolet rays. In particular, as shown in FIG. 1, when the content of the Sb ₂ O ₃ component is 0.5% or less, solarization is easily reduced to 5.0% or less. Thus, it is possible to easily obtain an optical glass that is difficult to deteriorate. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 0.5%, more preferably 0.3%, and most preferably 0.2%. Incidentally, the content of Sb ₂ O ₃ component is not particularly disadvantageous technically Within this range, as shown in FIG. 1, the content of Sb ₂ O ₃ component greater than 0% Thus, solarization can be reduced as compared with the case where no Sb ₂ O ₃ component is contained. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide equivalent composition is preferably more than 0%, more preferably 0.0001%, and most preferably 0.001%. As the Sb ₂ O ₃ component, for example, 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.

The Pt component is a component that is mixed into the optical glass from a member such as a platinum crucible when the optical glass is manufactured, which contributes to an increase in solarization of the optical glass by irradiation with ultraviolet rays. In particular, as shown in FIG. 2, by making the content of the Pt component of the optical glass 15 ppm or less, solarization is likely to be reduced, so that it is easy to obtain an optical glass whose spectral transmittance hardly changes even when used for a long time. can do. Therefore, the content of the Pt component in the optical glass is preferably 15 ppm, more preferably 10 ppm, and most preferably 7 ppm. The Pt component is a component contained in the optical glass by elution from a member containing platinum, such as a platinum crucible, even if the Pt component is not included as a material. Therefore, for example, by shortening the melting time of the glass in the platinum crucible or lowering the melting temperature of the glass, the mixing amount into the optical glass can be reduced. As shown in FIG. 2, in addition to the suppression of the content of the Pt component, the suppression of the content of the Sb ₂ O ₃ component is simultaneously performed, so that the solarization of the optical glass is more easily reduced. Also at this time, by making the content of the Sb ₂ O ₃ component more than 0%, solarization can be lowered as compared with the case where the Sb ₂ O ₃ component is not contained.

The Fe component is a component mixed into the optical glass, for example, as an impurity of the raw material of the optical glass when the optical glass is manufactured, and contributes to the enhancement of solarization of the optical glass by irradiation with ultraviolet rays. In particular, as shown in FIG. 3, by making the content of the Fe component 50 ppm or less, solarization is easily reduced to 5.0% or less. Can be easily obtained. Therefore, the upper limit of the content of the Fe component with respect to the total glass mass of the oxide conversion composition is preferably 50 ppm, more preferably 10 ppm, and most preferably 5 ppm. As the Fe component, for example, by selecting a raw material for optical glass having a small amount of Fe component, the amount mixed into the optical glass can be reduced. In addition to suppression of the content of the Fe component, simultaneous suppression of the contents of the Sb ₂ O ₃ component and the Pt component makes it easier to reduce the solarization of the optical glass.

<About essential and optional components>
Next, the essential components and optional components of the glass that are preferably used as the optical glass of the present invention will be described.

The SiO ₂ component is an oxide that forms glass, and is a useful component for forming a glass skeleton. In particular, when the content of the SiO ₂ component is 1.0% or more, the glass network structure increases to such an extent that a stable glass can be obtained, so that the devitrification resistance of the glass can be improved. On the other hand, by setting the content of SiO ₂ component below 60.0%, the refractive index of the glass is hardly lowered, it is possible to easily obtain an optical glass having a desired refractive index. Accordingly, the content of the SiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 5.0%, and most preferably 10.0% as the lower limit, preferably 60.0. %, More preferably 50.0%, and most preferably 40.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The Nb ₂ O ₅ component is a component that decreases the partial dispersion ratio (θg, F) of the glass and increases the refractive index of the glass. In particular, by setting the content of the Nb ₂ O ₅ component to 65.0% or less, it is possible to suppress a decrease in devitrification resistance and to easily obtain a glass having a desired dispersibility. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 65.0%, more preferably 60.0%, and most preferably 55.0%. In the optical glass of the present invention, the desired refractive index and partial dispersion ratio (θg, F) can be easily obtained by making the content of the Nb ₂ O ₅ component 10.0% or more. Therefore, the content of the Nb ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 15.0%, and most preferably 20.0%. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

TiO ₂ component increases the refractive index of the glass, a component to lower the Abbe number of the glass, an optional component of the optical glass of the present invention. By setting the content of the TiO ₂ component to 40.0% or less, the internal transmittance particularly in a short wavelength region (500 nm or less) of visible light is hardly deteriorated, so that coloring to glass can be reduced. Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 40.0%, more preferably 30.0%, and most preferably 20.0%. In the optical glass of the present invention, without containing TiO ₂ component, although it is possible to produce a reduced optical glass solarization, by containing a TiO ₂ component is easier to obtain a desired refractive index be able to. Therefore, the content of the TiO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably more than 0%, more preferably 0.1%, and most preferably 1.0%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

The B ₂ O ₃ component is an oxide that forms glass, is a component useful for forming a glass skeleton, and is an optional component in the optical glass of the present invention. In particular, when the content of the B ₂ O ₃ component is 40.0% or less, the refractive index of the glass is hardly lowered, and the internal transmittance in a short wavelength region of visible light is hardly deteriorated. Therefore, the content of the B ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 40.0%, more preferably 20.0%, and most preferably 10.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material. In the optical glass of the present invention, an optical glass with reduced solarization can be produced without containing the B ₂ O ₃ component, but the content of the B ₂ O ₃ component is 0.1% or more. By doing so, the optical glass with improved devitrification resistance can be obtained more easily. Therefore, the content of the B ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%.

The GeO ₂ component is a component that increases the refractive index of the glass and stabilizes the glass to reduce devitrification during molding, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the GeO ₂ component to 30.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the material cost of the glass can be reduced. Therefore, the content of the GeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The Al ₂ O ₃ component is a component that improves the chemical durability of the glass, and is an optional component in the optical glass of the present invention. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The ZrO ₂ component is a component that has the effect of lowering the liquidus temperature of the glass to increase the devitrification resistance, improving the chemical durability of the glass, and lowering the partial dispersion ratio (θg, F) of the glass. , An optional component in the optical glass of the present invention. In particular, the chemical durability of the glass can be increased by setting the content of the ZrO ₂ component to 20.0% or less. Therefore, the content of the ZrO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 11.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass and decreases the devitrification temperature of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be maintained by setting the content of the Ta ₂ O ₅ component to 20.0% or less. Therefore, the content of the Ta ₂ O ₅ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The WO ₃ component is a component that increases the refractive index of the glass and decreases the devitrification temperature of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the WO ₃ component to 20.0% or less, it is possible to make it difficult to deteriorate the transmittance particularly in the short wavelength region (500 nm or less) of visible light. Therefore, the content of the WO ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The ZnO component is a component that lowers the devitrification temperature of the glass and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. In particular, the chemical durability of the glass can be enhanced by setting the content of the ZnO component to 30.0% or less. Accordingly, the content of the ZnO component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

The MgO component is a component that lowers the melting temperature of the glass and is an optional component in the optical glass of the present invention. In particular, the chemical durability of the glass can be increased by setting the content of the MgO component to 20.0% or less. Therefore, the content of the MgO component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The MgO component can be contained in the glass using, for example, MgO, MgCO ₃ , MgF ₂ or the like as a raw material.

The CaO component is a component that lowers the devitrification temperature of the glass and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be improved by setting the content of the CaO component to 30.0% or less. Therefore, the content of the CaO component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The SrO component is a component that lowers the devitrification temperature of the glass and adjusts the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be enhanced by setting the content of the SrO component to 30.0% or less. Therefore, the content of the SrO component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

The BaO component is a component that lowers the devitrification temperature of the glass and adjusts the optical constant of the glass. In particular, the devitrification resistance of the glass can be improved by setting the content of the BaO component to 30.0% or less. Therefore, the content of the BaO component with respect to the total glass mass of the oxide-converted composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

In the optical glass of the present invention, the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) lowers the devitrification temperature of the glass as described above, and is refracted. Although it is a useful component for adjusting the rate, if the total content of these RO components is too large, the devitrification resistance of the glass tends to deteriorate. Therefore, the total content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. In the optical glass of the present invention, it is possible to produce an optical glass with reduced solarization without containing an RO component, but by making the total content of RO components 1.0% or more, Adjustment of the optical constant of the glass can be facilitated. Therefore, the total content of the RO component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%.

The Li ₂ O component is a component that lowers the partial dispersion ratio (θg, F) of the glass, lowers the devitrification temperature of the glass, and lowers the glass transition point (Tg), and is an optional component in the optical glass of the present invention. It is. In particular, when the content of the Li ₂ O component is 20.0% or less, solarization becomes difficult to increase, so that an optical glass with reduced solarization can be easily obtained. Therefore, the content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. In the optical glass of the present invention, although it is possible even without containing a Li 2 _O component to produce a reduced optical glass solarization, the total content of Li 2 _O component above 0.1% By doing so, since the glass transition point (Tg) becomes low, it is possible to obtain a glass that is easy to press-mold. Therefore, the total content of the Li ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 0.1%, more preferably 0.5%, and most preferably 1.0%. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

Na 2 _O component is a component for glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, when the content of the Na ₂ O component is 30.0% or less, an increase in the devitrification temperature of the glass can be suppressed, and thus vitrification can be facilitated. Therefore, the content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 15.0%. In the optical glass of the present invention, although it is possible even without containing Na 2 _O component to produce a reduced optical glass solarization, the total Na 2 _O content component than 0.1% By doing so, since the glass transition point (Tg) becomes low, it is possible to obtain a glass that is easy to press-mold. Therefore, the total content of the Na ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 2.0%, and most preferably 3.0%. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component for glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, when the content of the K ₂ O component is 20.0% or less, an increase in the devitrification temperature of the glass can be suppressed, and thus vitrification can be facilitated. Therefore, the content of the K ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 2.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

In the optical glass of the present invention, the mass sum of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 20.0% or less. preferable. By making this mass sum 20.0% or less, an increase in the devitrification temperature of the glass can be suppressed, so that vitrification can be facilitated. Therefore, the mass sum of the content of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 20.0%, more preferably 17.0%, and most preferably 15.0%. In the optical glass of the present invention, it is possible to produce an optical glass with reduced solarization without containing the Rn ₂ O component, but the total content of the Rn ₂ O component is 1.0% or more. By doing so, since the glass transition point (Tg) becomes low, it is possible to obtain a glass that is easy to press-mold. Therefore, the total content of the Rn ₂ O component with respect to the total glass mass of the oxide conversion composition is preferably 1.0%, more preferably 2.0%, and most preferably 5.0%.

The La ₂ O ₃ component is a component that increases the Abbe number of the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be improved by setting the content of the La ₂ O ₃ component to 50.0% or less. Therefore, the content of the La ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 50.0%, more preferably 20.0%, and most preferably 5.0%. As the La ₂ O ₃ component, for example, 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 Gd ₂ O ₃ component is a component that increases the Abbe number of the glass while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, the devitrification resistance of the glass can be enhanced by setting the content of the Gd ₂ O ₃ component to 30.0% or less. Therefore, the content of the Gd ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 10.0%, and most preferably 5.0%. As the Gd ₂ O ₃ component, for example, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

Y ₂ O ₃ component, while increasing the refractive index of the glass, or to enhance the devitrification resistance of the glass, an optional component of the optical glass of the present invention. In particular, by making the content of the Y ₂ O ₃ component 30.0% or less, an increase in the liquidus temperature of the glass can be suppressed, so that it is difficult to devitrify the glass when the glass is produced from a molten state. Can do. Therefore, the content of the Y ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 15.0%, and most preferably 5.0%. For the Y ₂ O ₃ component, for example, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

In the optical glass of the present invention, the mass sum of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Y, and Gd) is 30.0% or less. Is preferred. By making this mass sum 30.0% or less, the devitrification resistance of the glass can be enhanced. Therefore, the mass sum of the content of the Ln ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 30.0%, more preferably 15.0%, and most preferably 5.0%. .

Ga ₂ O ₃ component is a component that raises the refractive index of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the Ga ₂ O ₃ component to 20.0% or less, the usage amount of the expensive Ga ₂ O ₃ component is reduced, so that the material cost of the glass can be reduced. Therefore, the content of the Ga ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 20.0%, more preferably 15.0%, and most preferably 10.0%. The Ga ₂ O ₃ component can be contained in the glass using, for example, Ga ₂ O ₃ as a raw material.

TeO ₂ component increases the refractive index of the glass is a component of glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, by setting the content of the TeO ₂ component to 50.0% or less, it is possible to increase the internal transmittance of the glass while reducing the coloring of the glass. Therefore, the content of the TeO ₂ component with respect to the total glass mass of the oxide conversion composition is preferably 50.0%, more preferably 30.0%, still more preferably 15.0%, and most preferably 10. Less than 0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

Bi ₂ O ₃ component, increasing the refractive index of the glass is a component of glass transition point (Tg) lower, are optional components of the optical glass of the present invention. In particular, by setting the content of the Bi ₂ O ₃ component to 50.0% or less, it is possible to increase the internal transmittance of the glass while reducing the coloration of the glass. Therefore, the content of the Bi ₂ O ₃ component with respect to the total glass mass of the oxide conversion composition is preferably 50.0%, more preferably 30.0%, and even more preferably 15.0%, and most preferably It is less than 10.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The CeO ₂ component is a component that adjusts the optical constant of the glass and improves the solarization of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the CeO ₂ component is 10.0% or less, solarization of the glass can be reduced. Therefore, the CeO ₂ component content with respect to the total glass mass of the oxide conversion composition is preferably 10.0%, more preferably 5.0%, and most preferably 1.0%. However, when a CeO ₂ component is contained, absorption tends to occur at a specific wavelength in the visible range. Therefore, it is preferable that the CeO ₂ component is not substantially contained in terms of coloring of the glass. The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

Incidentally, components of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

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

In the optical glass of the present invention, other components can be added as necessary within a range not impairing the properties of the glass.

However, the transition metal components such as V, Cr, Mn, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, and Nb, are colored in the glass even when each of them is contained alone or in combination. Since there is a property of causing absorption at a specific wavelength in the visible region, it is preferable that the optical glass using the wavelength in the visible region does not substantially contain.

Furthermore, lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ and components of Th, Cd, Tl, Os, Be and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

The glass that is preferably used as the optical glass of the present invention cannot be expressed directly in the description of mol% because the composition is represented by mass% with respect to the total mass of the glass in terms of oxide composition, but is required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying various properties generally takes the following values in terms of oxide conversion.
SiO ₂ component 1.0-70.0 mol% and Nb ₂ O ₅ component 3.0-25.0 mol%
And TiO ₂ component 0 to 50.0 mol% and / or B ₂ O ₃ component 0 to 55.0 mol% and / or GeO ₂ component 0 to 30.0 mol% and / or Al ₂ O ₃ component 0 to 15 0.0 mol% and / or ZrO ₂ component 0 to 15.0 mol% and / or Ta ₂ O ₅ component 0 to 5.0 mol% and / or WO ₃ component 0 to 10.0 mol% and / or ZnO component 0-40.0 mol% and / or MgO component 0-45.0 mol% and / or CaO component 0-55.0 mol% and / or SrO component 0-30.0 mol% and / or BaO component 0- 20.0 mol% and / or Li ₂ O component 0-55.0 mol% and / or Na ₂ O component 0-45.0 mol% and / or K ₂ O component 0-20.0 mol% and / or la ₂ O ₃ component from 0 to 15.0 mol% and / or Gd O ₃ component from 0 to 10.0 mol% and / or _Y 2 _{O 3} component from 0 to 15.0 mol% and / or _Ga 2 _{O 3} component from 0 to 10.0 mol% and / or TeO ₂ components 0-30. 0 mol% and / or Bi ₂ O ₃ component 0 to 20.0 mol% and / or CeO ₂ component 0 to 3.0 mol%

<Physical properties>
The optical glass of the present invention preferably has a solarization of 5.0% or less. As a result, the device incorporating the optical glass is unlikely to deteriorate in color balance even after long-term use. In particular, since the solarization is greatly reduced as the use temperature is higher, the optical glass of the present invention is particularly effective when used at a high temperature as in a vehicle. Accordingly, the upper limit of solarization of the optical glass of the present invention is preferably 5.0%, more preferably 4.8%, and most preferably 4.5%. In the present specification, “solarization” refers to the amount of degradation of spectral transmittance at 450 nm when glass is irradiated with ultraviolet rays, and specifically, Japanese Optical Glass Industry Standard JOGIS 04-1994 “ According to “Measurement method of solarization of optical glass”, the spectral transmittance before and after irradiation with light from a high-pressure mercury lamp is measured.

The optical glass of the present invention has a desired partial dispersion ratio (θg, F) in the relational expression with the Abbe number (ν _d ), and can correct the chromatic aberration of the lens with higher accuracy. More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−1.60 × 10 ⁻³ ×) in the range of ν _d ≦ 25 with respect to the Abbe number (ν _d ). ν _d +0.6346) ≦ (θg, F) ≦ (−4.21 × 10 ⁻³ × ν _d +0.7207) and (−2.50 × 10 × 10) in the range of ν _d > 25. ⁻³ × ν _d +0.6571) ≦ (θg, F) ≦ (−4.21 × 10 ⁻³ × ν _d +0.7207). Accordingly, an optical glass having a desired partial dispersion ratio (θg, F) while having a low solarization can be obtained, so that the chromatic aberration of the lens in the optical apparatus can be corrected with high accuracy over a long period of time. Here, the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 25 is preferably (−1.60 × 10 ⁻³ × ν _d +0.6346), more preferably (−1.60 × 10 6). ⁻³ × ν _d +0.6366), most preferably (−1.60 × 10 ⁻³ × ν _d +0.6386). The partial dispersion ratio (θg, F) of the optical glass at ν _d > 25 is preferably (−2.50 × 10 ⁻³ × ν _d +0.6571), more preferably (−2.50 × 10 ^{−). 3} × ν _d +0.6591), and most preferably (−2.50 × 10 ⁻³ × ν _d +0.6611) is set as the lower limit. On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass is preferably (−4.21 × 10 ⁻³ × ν _d +0.7207), more preferably (−4.21 × 10 ⁻³ ×). (ν _d +0.7187), more preferably (−4.21 × 10 ⁻³ × ν _d +0.7177), and most preferably (−4.21 × 10 ⁻³ × ν _d +0.7172). In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the partial dispersion ratio (θg, F) of general glass is high. And the Abbe number (ν _d ) are represented by curves. However, since it is difficult to approximate this curve, the present invention uses a straight line having a different slope from ν _d = 25 as a partial dispersion ratio (θg, F) lower than that of general glass. Expressed.

The optical glass of the present invention preferably has a glass transition point (Tg) of 400 ° C. or higher and 650 ° C. or lower. When the glass transition point (Tg) is 400 ° C. or higher, adverse effects due to frictional heat generated when polishing the glass can be reduced. On the other hand, since the glass transition point (Tg) is 650 ° C. or lower, press molding at a lower temperature becomes possible, so that the oxidation of the mold used for mold press molding is reduced to extend the life. Can do. Accordingly, the glass transition point (Tg) of the optical glass of the present invention is preferably 400 ° C., more preferably 450 ° C., most preferably 500 ° C., preferably 650 ° C., more preferably 620 ° C., most preferably The upper limit is 600 ° C.

The optical glass of the present invention preferably has a yield point (At) of 450 ° C. or higher and 700 ° C. or lower. Like the glass transition point (Tg), the yield point (At) is one of indices indicating the softening property of glass, and is an index indicating a temperature close to the press molding temperature. Therefore, by using a glass having a yield point (At) of 450 ° C. or higher, adverse effects due to frictional heat generated when polishing the glass can be reduced. Further, by using a glass having a yield point (At) of 700 ° C. or lower, press molding at a lower temperature becomes possible, so that press molding can be performed more easily. Therefore, the yield point (At) of the optical glass of the present invention is preferably 450 ° C., more preferably 500 ° C., most preferably 540 ° C., preferably 700 ° C., more preferably 670 ° C., most preferably 650. C is the upper limit.

The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.78, more preferably 1.80, most preferably 1.82, and preferably 1.95. The upper limit is preferably 1.92, and most preferably 1.90. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 18, more preferably 20, most preferably 22, the lower limit, preferably 30, more preferably 28, and most preferably 27. . Accordingly, the degree of freedom in optical design can be expanded, and a large amount of light refraction can be obtained even if the device is made thinner.

[Method of suppressing deterioration of spectral transmittance of glass]
Next, a method for suppressing the deterioration of the spectral transmittance of the glass of the present invention will be described. In the spectral transmittance deterioration suppressing method of the present invention, the content of the Sb ₂ O ₃ component contained in the glass is reduced. Thereby, solarization of the glass is reduced even when irradiated with ultraviolet rays. For this reason, it is possible to easily obtain an optical glass in which deterioration of the spectral transmittance over time is suppressed. Here, it means for reducing the content of Sb ₂ O ₃ component is, for example, means for reducing the content of Sb ₂ O ₃ component contained in the raw material used, but is not limited thereto. Further, it is more effective to use a method for reducing the Pt component and the Fe component together.

[Production of glass and glass molded body]
The optical glass of the present invention and the glass used in the spectral transmittance degradation suppressing method of the present invention are produced, for example, as follows. That is, the raw materials are uniformly mixed so that each component is within a predetermined content range. The prepared mixture is put into a quartz crucible and roughly melted, and then put into a platinum crucible or a platinum alloy crucible, melted in a predetermined temperature range for a predetermined time, homogenized by stirring, and subjected to foam breakage or the like. Next, the temperature of the molten glass is lowered, cast into a mold, and slowly cooled to produce optical glass. Here, when the material is melted using a platinum crucible, it becomes possible to melt the glass at a high temperature. Therefore, a glass having a high melting temperature, for example, the above-described SiO ₂ component and Nb ₂ O ₅ component, and / or TiO _2. Even glass containing the component can be efficiently dissolved, but the Pt component is easily eluted from the platinum crucible into the glass. Therefore, in order to reduce the elution of the Pt component into the glass, the melting temperature of the glass is preferably 1400 ° C., more preferably 1300 ° C., most preferably 1200 ° C., and the melting time of the glass is preferably 6 hours. More preferably 4 hours, and most preferably 2 hours.

A glass molded body can be produced from the produced optical glass using means such as reheat press molding or precision press molding. That is, a lens preform for mold press molding is prepared from optical glass, and after reheat press molding is performed on the lens preform, polishing can be performed to prepare a glass molded body. Further, a glass molded body can be produced by precision press molding the lens preform produced by polishing. In addition, the means for producing the glass molded body is not limited to these means.

The glass molded body produced in this manner is useful for various optical elements, and among them, it is particularly preferable to use for optical elements such as lenses and prisms. Thereby, since the temporal degradation of the spectral transmittance of the optical element is suppressed, the color balance of the optical element can be hardly deteriorated even after long-term use.

Compositions of Examples (No. 1 to No. 159) and Comparative Examples (No. 1 to No. 2) of the present invention, concentrations of Pt component and Fe component of these glasses, refractive index ( _nd ), Tables 1 to 5 show the Abbe number (ν _d ), spectral transmittance at a wavelength of 450 nm before and after light irradiation, solarization, partial dispersion ratio (θg, F), glass transition point (Tg), and yield point (At). 22 shows. The following examples are merely for illustrative purposes, and are not limited to these examples.

The glass of Examples (No. 1 to No. 159) and Comparative Examples (No. 1 to No. 2) of the present invention are all oxides, hydroxides, carbonates corresponding to the raw materials of the respective components, High-purity raw materials used for ordinary optical glass such as nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. are selected, and the composition ratios of the respective examples and comparative examples shown in Tables 1 to 22 are obtained. And weighed uniformly. Thereafter, the mixture was put into a platinum crucible, melted in an electric furnace at a temperature range of 1200 to 1350 ° C. for 2 to 4 hours according to the difficulty of melting the glass composition, and homogenized by stirring to remove bubbles. Thereafter, the temperature of the molten glass was lowered to 1100 to 1200 ° C., homogenized by stirring, cast into a mold, and slowly cooled to produce a glass.

Here, the contents of the Pt component and Fe component of the glasses of the examples (No. 1 to No. 159) and the comparative examples (No. 1 to No. 2) are the same as those of the glasses having the compositions of the examples and comparative examples. The solution obtained by powdering and treating with an acid was measured using an ICP emission spectrometer (Vista-PRO manufactured by Seiko Instruments Inc.).

Further, the solarization of the glass of the examples (No. 1 to No. 159) and the comparative examples (No. 1 to No. 2) is described in Japan Optical Glass Industry Association Standard JOGIS04-1994 “Measurement Method of Solarization of Optical Glass”. Similarly, the change (%) in light transmittance at a wavelength of 450 nm before and after light irradiation was measured. Here, the light irradiation was performed by heating an optical glass sample to 100 ° C. and irradiating light with a wavelength of 450 nm for 4 hours using an ultrahigh pressure mercury lamp.

Further, the refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg, F) of the glass of Examples (No. 1 to No. 159) and Comparative Examples (No. 1 to No. 2). ) Was measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, regarding the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F), the slope a in the relational expression (θg, F) = − a × ν _d + b is 0.0016, 0.0020. And the intercept b at 0.00421 was obtained. The glass used in this measurement was a glass that had been treated in a slow cooling furnace at a slow cooling rate of −25 ° C./hr.

Further, the glass transition point (Tg) and the yield point (At) of the glass of the examples (No. 1 to No. 159) and the comparative examples (No. 1 to No. 2) were measured with a differential heat measuring device (manufactured by Netchgeletebau). It was determined by performing measurement using STA 409 CD). Here, the sample particle size at the time of measurement was 425 to 600 μm, and the temperature elevation rate was 10 ° C./min.

As shown in Tables 1 to 22, all of the optical glasses of the examples of the present invention have a solarization of 5.0% or less, more specifically 4.3% or less, and are within a desired range. It was. On the other hand, the glass of the comparative example had a solarization greater than 5.0%. Therefore, it became clear that the optical glass of the example of the present invention has reduced solarization of the optical glass due to the long-time irradiation of ultraviolet rays as compared with the glass of the comparative example.

The optical glass of the example of the present invention has a partial dispersion ratio (θg, F) of (−1.60 × 10 ⁻³ × ν _d +0.6346) or more when ν _d ≦ 25, more specifically (− 1.60 × 10 ⁻³ × ν _d +0.6497) or more. In the case of ν _d > 25, the partial dispersion ratio (θg, F) is (−2.50 × 10 ⁻³ × ν _d +0.6571) or more, more specifically (−2.50 × 10 ^−3). × ν _d +0.6670) or more. On the other hand, the partial dispersion ratio (θg, F) of the optical glass of the example of the present invention is (−4.21 × 10 ⁻³ × ν _d +0.7207) or less, more specifically (−4.21 × 10 ⁻³ × ν _d +0.7187) or less. Therefore, it was found that these partial dispersion ratios (θg, F) are within a desired range. On the other hand, the glasses of the comparative examples of the present invention all had a partial dispersion ratio (θg, F) exceeding (−4.21 × 10 ⁻³ × ν _d +0.7187). Therefore, it was clarified that the optical glass of the example of the present invention has a smaller partial dispersion ratio (θg, F) in the relational expression with the Abbe number (ν _d ) than the glass of the comparative example.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.78 or more, more specifically 1.82 or more, and the refractive index (n _d ) of 1.95 or less. More specifically, it was 1.90 or less, and was within a desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 18 or more, more specifically 22 or more, and this Abbe number (ν _d ) of 30 or less, more specifically 27. And within the desired range.

The optical glasses of the examples of the present invention all have a glass transition point (Tg) of 400 ° C. or higher, more specifically 500 ° C. or higher, and this glass transition point (Tg) is 650 ° C. or lower. It was 600 degrees C or less, and was in the desired range.

In addition, the optical glasses of the examples of the present invention all have a yield point (At) of 450 ° C. or higher, more specifically 540 ° C. or higher, and the yield point (At) is 700 ° C. or lower, more specifically. It was 650 degrees C or less, and was in the desired range.

Furthermore, after performing reheat press molding using the optical glass of the example of the present invention, grinding and polishing were performed and processed into the shape of a lens and a prism to obtain a glass molded body. Further, a lens preform for precision press molding was formed using the optical glass of the example of the present invention, and this lens preform was precision press molded to obtain a glass molded body. As a result, in the optical glass of the example of the present invention, the content of the Sb ₂ O ₃ component is not more than a predetermined amount, and the obtained glass molded body has little solarization, and has a predetermined spectral transmission as a lens and a prism over a long period of time. The glass molded object which can have a rate was able to be obtained. On the other hand, the glass of the comparative example contained a predetermined or higher Sb ₂ O ₃ component, and the obtained glass molded body was easily colored by ultraviolet rays. Therefore, the glass molded body produced from the optical glass of the example of the present invention has a reduced solarization as compared with the glass molded body produced from the glass of the comparative example, and the spectral transmittance is deteriorated over time. It became clear that was suppressed.

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

Claims (14)

1. The content of Sb ₂ O ₃ component is 0.5% or less in terms of mass% with respect to the total glass mass of oxide conversion composition, and solarization (amount of degradation of spectral transmittance at a wavelength of 450 nm) is 5.0% or less. Optical glass that is.
2. The optical glass according to claim 1, wherein the content of the Pt component is 15 ppm or less.
3. The optical glass according to claim 1 or 2, wherein the content of the Fe component is 50 ppm or less with respect to the total mass of the glass having an oxide equivalent composition.
4. The optical glass according to any one of claims 1 to 3, comprising a SiO ₂ component, a Nb ₂ O ₅ component, and / or a TiO ₂ component.
5. Containing 1.0% or more and 60.0% or less of SiO ₂ component and 10.0% or more and 65.0% or less of Nb ₂ O ₅ component in mass% with respect to the total glass mass of oxide conversion composition, The optical glass according to claim 4, wherein the content of the TiO ₂ component is 40.0% or less.
6. B ₂ O ₃ component 0 to 40.0% and / or GeO ₂ component 0 to 30.0% and / or Al ₂ O ₃ component 0 to 0% by mass with respect to the total mass of the glass in oxide equivalent composition 15.0% and / or ZrO ₂ component 0 to 20.0% and / or Ta ₂ O ₅ component 0 to 20.0% and / or WO ₃ component 0 to 20.0% and / or ZnO Component 0-30.0% and / or MgO component 0-20.0% and / or CaO component 0-30.0% and / or SrO component 0-30.0% and / or BaO component 0 -30.0% and / or Li ₂ O component 0-20.0% and / or Na ₂ O component 0-30.0% and / or K ₂ O component 0-20.0%
   The optical glass according to claim 1, further comprising:
7. La ₂ O ₃ component 0 to 50.0% and / or Gd ₂ O ₃ component 0 to 30.0% and / or Y ₂ O ₃ component in mass% with respect to the total mass of the glass in oxide conversion composition 0 to 30.0%, and / or Ga ₂ O ₃ component 0 to 20.0%, and / or TeO ₂ component 0 to 50.0%, and / or Bi ₂ O ₃ component 0 to 50.0%, And / or CeO ₂ component 0-10.0%
   The optical glass according to claim 1, further comprising:
8. (−1.60 × 10 ⁻³ × ν _d +0.6346) ≦ (θg, F) ≦ within the range where the partial dispersion ratio (θg, F) is Abbe number (ν _d ) and v _d ≦ 25. (−4.21 × 10 ⁻³ × ν _d +0.7207) is satisfied, and in the range of ν _d > 25, (−2.50 × 10 ⁻³ × ν _d +0.6571) ≦ (θg, F) The optical glass according to any one of claims 1 to 7, wherein a relationship of ≦ (−4.21 × 10 ⁻³ × ν _d +0.7207) is satisfied.
9. The optical glass according to any one of claims 1 to 8, wherein the glass transition point (Tg) is 400 ° C or higher and 650 ° C or lower.
10. An optical element using the optical glass according to any one of claims 1 to 9 as a base material.
11. A lens preform comprising the optical glass according to any one of claims 1 to 9.
12. A lens preform for mold press molding comprising the optical glass according to any one of claims 1 to 9.
13. An optical element formed by molding the lens preform according to claim 11 or 12.
14. A method for suppressing deterioration of spectral transmittance of glass,
    A method for suppressing degradation of spectral transmittance, which reduces the content of Sb ₂ O ₃ component contained in glass.

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