JP6161352B2 - Optical glass, lens preform and optical element - Google Patents

Description

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

  In recent years, the digitization and high definition of devices that use optical systems have been rapidly progressing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, The demand for light weight and downsizing is increasing.

Among optical glasses for producing an optical element, in particular, it has a high refractive index (n _d ) of 1.70 or more and 2.20 or less that can reduce the weight and size of the optical element, but is lower. The demand for glass having an Abbe number (ν _d ) is very high. As a glass having a high refractive index and a low Abbe number, for example, a refractive index (n _d ) is 1.81 or more, and an optical glass having an Abbe number of 23 or less is represented by Patent Documents 1 to 5. Glass is known. Further, as an optical glass having a refractive index (n _d ) of 1.92 or more and an Abbe number of approximately 18 or so, a glass represented by Patent Document 6 is known.

JP 2010-260745 A JP 2011-144063 A JP 2011-144064 A JP 2011-144065 A JP 2011-1444066 A JP 2011-057509 A

  When producing an optical element using such glass, a method of grinding and polishing a glass molded product obtained by heat softening and press molding (reheat press molding), or cutting and polishing a gob or a glass block The preform material or the preform material formed by known flotation molding is heat-softened and press-molded with a mold having a highly accurate molding surface (precision press molding).

However, since the glass disclosed in Patent Documents 1 to 5 cannot be said to have a sufficiently low Abbe number (ν _d ), there is a demand for an optical glass that has a lower Abbe number and can improve imaging characteristics and the like. It was. On the other hand, although the glass disclosed in Patent Document 6 has an Abbe number lower than that of Patent Documents 1 to 5, when mold press molding such as reheat press molding or precision press molding is performed, the glass becomes milky. Or devitrification, the optical characteristics of the optical element are adversely affected. For this reason, the glass disclosed in Patent Document 6 is not suitable for use as an optical element that transmits light in the visible region, for example.

The present invention has been made in view of the above-mentioned problems, and the object thereof is an optical glass having a high refractive index (n _d ) while having a lower Abbe number (ν _d ). Another object of the present invention is to provide an optical glass having high thermal stability, and a lens preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies, and as a result, the P ₂ O ₅ component and the Nb ₂ O ₅ component are used in combination, and the content of other components is adjusted, whereby glass It has been found that the crystallization start temperature of the glass can be increased while the Abbe number is lower, and the present invention has been completed. Specifically, the present invention provides the following.

(1) By mass%, the P ₂ O ₅ component is contained in the range of 5.0% to 40.0% and the Nb ₂ O ₅ component is contained in the range of 10.0% to 60.0%, and an Abbe number of 20 or less (ν _d ) an optical glass having a difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) of 100 ° C. or more.

(2) The optical glass according to (1), wherein the content of the TiO ₂ component is more than 0% and not more than 30.0% by mass.

(3) The optical glass according to (1) or (2), wherein the mass ratio TiO ₂ / Nb ₂ O ₅ is 0.10 or more and 2.00 or less.

(4) The optical glass according to any one of (1) to (3), wherein the content of the WO ₃ component is 35.0% or less by mass.

(5) mass ratio _WO 3 _/ P 2 _{O 5} is 0.60 or less (1) to (4) any description of the optical glass.

(6) The optical glass according to any one of (1) to (5), wherein the sum of the contents of the P ₂ O ₅ component, the Nb ₂ O ₅ component, and the WO ₃ component is 60.0% or more and 80.0% or less. .

(7) By mass%
Li ₂ O component 0-5.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 15.0%
The optical glass according to any one of (1) to (6).

(8) The optical glass according to (7), which is contained by mass and contains more than 0% of a K ₂ O component.

(9) the weight ratio _Na 2 O / _{K 2} O is one wherein the optical glass is 3.00 or less (1) to (8).

(10) Weight ratio _{P 2 O} 5 / Na 2 _O is one wherein the optical glass is 3.00 or more (1) to (9).

(11) The optical glass according to any one of (1) to (10), wherein the sum of the contents of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component is 20.0% or less.

(12) The mass ratio (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) / (Li ₂ O + Na ₂ O + K ₂ O) is 8.00 or more and 15.00 or less, according to any one of (1) to (11) Optical glass.

(13) In mass%,
BaO component 0 to 20.0%
Bi ₂ O ₃ component 0 to 15.0%
The optical glass according to any one of (1) to (12).

(14) The optical glass according to any one of (1) to (13), wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, the WO ₃ component, and the Bi ₂ O ₃ component is 30.0% or more.

(15) The optical glass according to any one of (1) to (14), wherein the mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) is 0.100 or more.

(16) The optical component according to any one of (1) to (15), wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, the WO ₃ component, the Na ₂ O component, and the BaO component is 80.0% or less. Glass.

(17) The optical glass according to any one of (1) to (16), wherein the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Na ₂ O + BaO) / (P ₂ O ₅ + K ₂ O) is 4.00 or less.

(18) The optical glass according to any one of (1) to (17), wherein the content of the B ₂ O ₃ component is 10.0% by mass or less.

(19) Any one of (1) to (18), wherein the sum of the contents of B ₂ O ₃ component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component is 20.0% or less Optical glass.

(20) 0 to 5.0% MgO component by mass%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
The optical glass according to any one of (1) to (19).

  (21) The optical glass according to any one of (1) to (20), wherein the sum of the contents of the MgO component, CaO component, SrO component, and BaO component is 20.0% or less.

(22) Y ₂ O ₃ component in mass% 0 to 10.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (21).

(23) The optical glass according to any one of (1) to (22), wherein the sum of the contents of the Y ₂ O ₃ component, the La ₂ O ₃ component, and the Gd ₂ O ₃ component is 15.0% or less.

(24) SiO ₂ component by mass% 0 to 10.0%
GeO ₂ component 0-10.0%
TeO ₂ component 0-15.0%
ZrO ₂ component 0 to 10.0%
ZnO component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) to (23).

(25) 1.70 to 2.20 or less in refractive index _{(n d)} any description of the optical glass (1) to (24) having a.

(26) The optical glass according to any one of (1) to (25), wherein a wavelength (λ ₇₀ ) having a spectral transmittance of 70% is 500 nm or less.

  (27) An optical element having the optical glass according to any one of (1) to (26) as a base material.

  (28) A lens preform comprising the optical glass according to any one of (1) to (26).

  (29) A lens preform for mold press molding comprising the optical glass according to any one of (1) to (26).

  (30) An optical element formed by molding the lens preform according to (28) or (29).

According to the present invention, in an optical glass having a high refractive index (n _d ), an optical glass having a high thermal stability while having a lower Abbe number (ν _d ), and a lens plate using the same. Reforms and optical elements can be provided.

The optical glass of the present invention contains, in mass%, a P ₂ O ₅ component of 5.0% to 40.0%, a Nb ₂ O ₅ component of 10.0% to 60.0%, and 20 or less. It has an Abbe number (ν _d ), and the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 100 ° C. or more. By using the P ₂ O ₅ component and the Nb ₂ O ₅ component together and adjusting the content of other components, the glass crystallization start temperature is increased while the glass Abbe number is lower. Even if the glass is heated above the glass transition point, it is difficult to crystallize. Therefore, in an optical glass having a high refractive index (n _d ), an optical glass having a low Abbe number (ν _d ) and a high thermal stability, and a lens preform and an optical element using the optical glass Can provide.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise specified in the present specification, the contents of the respective components are all expressed in mass% with respect to the total mass of the glass in terms of oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass component of the present invention are all decomposed and changed into an oxide when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

<About essential and optional components>
The P ₂ O ₅ component is a glass forming component and is an essential component effective for reducing the glass Abbe number. In particular, by containing 5.0% or more of the P ₂ O ₅ component, the visible light transmittance of the glass can be increased and the devitrification resistance can be increased. Therefore, the content of the P ₂ O ₅ component is preferably 5.0%, more preferably 10.0%, still more preferably 15.0%, still more preferably 20.0%, and even more preferably 23.0%. Is the lower limit.
On the other _hand, when the content of P 2 _{O 5} component below 40.0%, suppressed the decrease in the refractive index. Therefore, the content of the P ₂ O ₅ component is preferably 40.0%, more preferably 35.0%, and still more preferably 30.0%.
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 or the like can be used as a raw material.

The Nb ₂ O ₅ component is an essential component that increases the refractive index of the glass and decreases the Abbe number. In particular, by containing 10.0% or more of the Nb ₂ O ₅ component, the Abbe number can be lowered while obtaining a desired high refractive index. Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0%, more preferably 22.0%, still more preferably 30.0%, and further preferably 36.0%.
On the other hand, by making the content of the Nb ₂ O ₅ component 60.0% or less, the meltability of the glass can be enhanced, and the coloration of the glass can be reduced by lowering the melting temperature. This also increases the devitrification resistance of the glass. Therefore, the content of the Nb ₂ O ₅ component is preferably 60.0%, more preferably 50.0%, further preferably 47.5%, and further preferably 45.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The TiO ₂ component is an optional component that can increase the refractive index of the glass, decrease the Abbe number, and increase the chemical durability when it is contained in an amount of more than 0%. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 5.0%, still more preferably more than 10.0%, still more preferably more than 15.0%, still more preferably 16.0%. More preferably, it may be more than 16.2%, more preferably more than 17.5%, still more preferably more than 18.7%.
On the other hand, by setting the content of the TiO ₂ component to 30.0% or less, the visible light transmittance of the glass can be increased, and the thermal stability of the glass can be increased. Therefore, the upper limit of the content of the TiO ₂ component is preferably 30.0%, more preferably 25.0%, and still more preferably 23.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The ratio (mass ratio) of the content of the TiO ₂ component to the content of the Nb ₂ O ₅ component is preferably 0.10 or more and 2.00 or less.
In particular, by setting this ratio to 0.10 or more, the Abbe number of the glass can be further reduced. Therefore, the lower limit of the mass ratio TiO ₂ / Nb ₂ O ₅ is preferably 0.10, more preferably 0.18, still more preferably 0.25, and still more preferably 0.33.
On the other hand, by setting the ratio to 2.00 or less, the visible light transmittance can be increased by reducing the coloring of the glass. Therefore, the upper limit of the mass ratio TiO ₂ / Nb ₂ O ₅ is preferably 2.00, more preferably 1.50, still more preferably 1.00, and still more preferably 0.60.

The WO ₃ component is an optional component that can increase the refractive index of the glass and decrease the Abbe number of the glass when it contains more than 0%.
In particular, by setting the content of the WO ₃ component to 35.0% or less, the glass transition point can be lowered, and the visible light transmittance and thermal stability of the glass can be increased. Accordingly, the content of the WO ₃ component is preferably 35.0%, more preferably 25.0%, further preferably 15.0%, more preferably less than 10.0%, and still more preferably 85.0%. The upper limit is set to 0.0%, more preferably 7.0%, more preferably 6.0%, and still more preferably 5.1%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The ratio (mass ratio) of the content of the WO ₃ component to the content of the P ₂ O ₅ component is preferably 0.60 or less. Thereby, the visible light transmittance of the glass can be increased, coloring can be reduced, and the thermal stability of the glass can be increased. Accordingly, the mass ratio WO ₃ / P ₂ O ₅ is preferably 0.60, more preferably 0.40, still more preferably 0.33, still more preferably 0.30, still more preferably 0.25, and even more preferably. 0.21 is the upper limit.
On the other hand, this ratio may be 0, but by making it larger than 0, a desired low Abbe number can be easily obtained. Therefore, the mass ratio WO ₃ / P ₂ O ₅ is preferably greater than 0, more preferably greater than 0.05, and even more preferably greater than 0.10.

The total content (mass sum) of the P ₂ O ₅ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 60.0% or more and 80.0% or less.
In particular, by making this total amount 60.0% or more, the Abbe number of the glass can be lowered. Therefore, the mass sum (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) is preferably 60.0%, more preferably 65.0%, and further preferably 66.5%.
On the other hand, the devitrification resistance of glass can be improved by making this total amount 80.0% or less. Therefore, the upper limit of the mass sum (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) is preferably 80.0%, more preferably 78.0%, and still more preferably 76.0%.

Li 2 _O component, when ultra containing 0%, which is an optional component that can be lowered glass transition temperature.
On the other hand, by making the content of the Li ₂ O component 5.0% or less, it is possible to suppress a decrease in the refractive index and reduce devitrification due to the inclusion of the Li ₂ O component. Therefore, the content of the Li ₂ O component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, still more preferably 0.7%, and even more preferably 0.4%. The upper limit is set, more preferably less than 0.3%, and still more preferably not contained. 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.

When the Na ₂ O component is contained in an amount of more than 0%, the glass transition point can be lowered, the devitrification resistance can be increased, and the visible light transmittance of the glass can be increased. Therefore, the content of the Na ₂ O component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 0.8%.
On the other hand, by setting the content of the Na ₂ O component to 15.0% or less, it is possible to suppress a decrease in the refractive index and reduce devitrification due to excessive content of the Na ₂ O component. This also increases the thermal stability of the glass. Therefore, the content of the Na ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 5.8%, further preferably 4.4%, further preferably 3.6%. The upper limit is set, more preferably less than 2.9%.
As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like can be used as a raw material.

The K ₂ O component is an optional component that can lower the glass transition point and increase the resistance to devitrification when it contains more than 0%. Further, K 2 _O ingredient is also a component enhances the thermal stability of the glass. Therefore, the content of the K ₂ O component is preferably more than 0%, more preferably more than 1.0%, still more preferably 1.5% or more, and further preferably more than 3.0%.
On the other hand, by setting the content of the K ₂ O component to 15.0% or less, it is possible to suppress a decrease in the refractive index and reduce devitrification due to excessive inclusion of the K ₂ O component. Therefore, the upper limit of the content of the K ₂ O component is preferably 15.0%, more preferably 10.0%, and still more preferably 6.0%.
As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used as a raw material.

The ratio (mass ratio) of the content of the Na ₂ O component to the content of the K ₂ O component is preferably 3.00 or less. Thereby, since the crystallization start temperature of glass is raised, the thermal stability of glass can be raised. Accordingly, the mass ratio Na ₂ O / K ₂ O preferably has an upper limit of 3.00, more preferably less than 2.00, even more preferably less than 1.50, still more preferably less than 1.20, and even more preferably 1. Less than 0.00.
On the other hand, the lower limit of this ratio is preferably greater than 0, more preferably greater than 0.10, and even more preferably greater than 0.15, from the viewpoint of suppressing a decrease in the devitrification resistance of the glass.

The ratio (mass ratio) of the content of the P ₂ O ₅ component to the content of the Na ₂ O component is preferably 3.00 or more. Thereby, since the crystallization start temperature of glass is raised, the thermal stability of glass can be raised. Therefore, the mass ratio P ₂ O ₅ / Na ₂ O is preferably 3.00, more preferably 4.00, still more preferably 5.00, even more preferably 6.00, and even more preferably 7.00. To do.
On the other hand, the upper limit of this ratio is preferably 50.00, more preferably 40.00, and even more preferably 30.00.

The total content (mass sum) of the Li ₂ O component, Na ₂ O component and K ₂ O component is preferably 20.0% or less.
In particular, when the total amount is 20.0% or less, a decrease in the refractive index of the glass and an increase in the Abbe number can be suppressed. Further, the devitrification resistance of the glass is also improved. Accordingly, the upper limit of the mass sum (Li ₂ O + Na ₂ O + K ₂ O) is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 7.35%. In particular, by increasing the total content of the above-mentioned P ₂ O ₅ component, Nb ₂ O ₅ component and WO ₃ component, while reducing the total content of Li ₂ O component, Na ₂ O component and K ₂ O component Thus, a glass having a smaller Abbe number can be obtained.
On the other hand, this total amount may be greater than 0%. Thereby, the glass transition point (Tg) can be lowered and the water resistance of the glass can be increased. Therefore, the mass sum (Li ₂ O + Na ₂ O + K ₂ O) is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and even more preferably 5.0%.

The ratio (mass ratio) of the total content of P ₂ O ₅ component, Nb ₂ O ₅ component and WO ₃ component to the total content of Li ₂ O component, Na ₂ O component and K ₂ O component is 8.00. Above 15.00 is preferable.
In particular, by setting this ratio to 8.00 or more, the Abbe number of the glass can be further reduced. Therefore, the mass ratio (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) / (Li ₂ O + Na ₂ O + K ₂ O) is preferably 8.00, more preferably 8.20, still more preferably 9.00, and even more preferably Has a lower limit of 9.50.
On the other hand, the devitrification resistance of glass can be improved by setting this ratio to 15.00 or less. Therefore, the mass ratio (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) / (Li ₂ O + Na ₂ O + K ₂ O) is preferably 15.00, more preferably 14.00, and still more preferably 13.50. To do.

The BaO component is an optional component that can increase the refractive index of the glass and increase the devitrification resistance when the content of BaO exceeds 0%.
On the other hand, by setting the content of the BaO component to 20.0% or less, a decrease in refractive index and an increase in Abbe number can be suppressed, and a decrease in devitrification resistance and chemical durability can be suppressed. This also increases the thermal stability of the glass. Therefore, the content of the BaO component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, more preferably less than 2.0%, still more preferably 0.7%. %.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that increases the refractive index and decreases the Abbe number when it exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 15.0% or less, the devitrification resistance of the glass can be increased, and the coloring of the glass can be reduced to increase the visible light transmittance. Accordingly, the upper limit of the content of the Bi ₂ O ₃ component is preferably 15.0%, more preferably 5.0%, still more preferably 1.0%, and still more preferably 0.3%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The total content (mass sum) of the TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component, and Bi ₂ O ₃ component is preferably 30.0% or more and 80.0% or less.
In particular, when the total amount is 30.0% or more, the refractive index of the glass can be increased and the Abbe number can be lowered. Accordingly, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) is preferably 30.0%, more preferably 40.0%, still more preferably 51.0%, and even more preferably 63.0%. Is the lower limit.
On the other hand, by making this total amount 80.0% or less, the visible light transmittance of the glass can be increased and coloring can be reduced. Accordingly, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) is preferably 80.0%, more preferably 75.0%, still more preferably 70.0%, and even more preferably 69.0%. Is the upper limit.

The ratio (mass ratio) of the content of TiO ₂ component and Bi ₂ O ₃ component to the total content of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component and Bi ₂ O ₃ component is 0.10 or more. preferable. As a result, the refractive index of the glass can be increased, the Abbe number can be further lowered, and a decrease in devitrification resistance can be suppressed. Therefore, the mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) is preferably 0.10, more preferably 0.15, still more preferably 0.20, Preferably, the lower limit is 0.245.
On the other hand, the upper limit of this ratio is preferably 0.50, more preferably 0.40, and even more preferably 0.35 from the viewpoint of increasing the visible light transmittance of the glass and reducing the coloration.

The total content (mass sum) of the TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component, Na ₂ O component and BaO component is preferably 80.0% or less. Thereby, since the crystallization start temperature of glass is raised, the thermal stability of glass can be raised. Therefore, the upper limit of the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Na ₂ O + BaO) is preferably 80.0%, more preferably 75.0%, and still more preferably 72.0%.
On the other hand, the lower limit of the total amount is preferably 30.0%, more preferably 50.0%, and even more preferably 60.0% from the viewpoint of suppressing a decrease in the devitrification resistance of the glass. .

The ratio (mass ratio) of the total content of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component, Na ₂ O component and BaO component to the total content of P ₂ O ₅ component and K ₂ O component is 4 0.000 or less is preferable. Thereby, since the crystallization start temperature of glass is raised, the thermal stability of glass can be raised. Therefore, the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Na ₂ O + BaO) / (P ₂ O ₅ + K ₂ O) is preferably 4.00, more preferably 3.50, still more preferably 3.00, The upper limit is preferably 2.50.
On the other hand, the lower limit of this ratio is preferably 0.50, more preferably 1.00, still more preferably 1.50, and still more preferably 2.00, from the viewpoint of suppressing a decrease in the devitrification resistance of the glass. It is good.

B ₂ O ₃ component, when ultra containing 0%, which is an optional component that enhances devitrification resistance of the glass.
On the other hand, by making the content of the B ₂ O ₃ component 10.0% or less, it is possible to suppress a decrease in the refractive index and an increase in the Abbe number. This also increases the thermal stability of the glass. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%, still more preferably 0.4%. Is the upper limit, more preferably less than 0.3%, and still more preferably not contained.
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 or the like can be used as a raw material.

The total content (mass sum) of the B ₂ O ₃ component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component is preferably 20.0% or less. By reducing this total amount, an increase in Abbe number due to excessive inclusion of these components can be suppressed. Accordingly, the mass sum (B ₂ O ₃ + BaO + Li ₂ O + Na ₂ O + K ₂ O) is preferably 12.0%, more preferably less than 10.5%, even more preferably less than 9.5%, and even more preferably. The upper limit is 9.0%.

The MgO component, CaO component and SrO component are optional components that can enhance the devitrification resistance of the glass when they are contained in excess of 0%.
On the other hand, when the content of the MgO component is 5.0% or less, a decrease in refractive index and an increase in Abbe number can be suppressed. Therefore, the content of the MgO component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%.
In addition, by reducing the content of each of the CaO component and the SrO component to 10.0% or less, a decrease in refractive index and an increase in the Abbe number can be suppressed, and devitrification resistance and chemical properties due to excessive inclusion of these components. The deterioration of mechanical durability is also suppressed, and the thermal stability of the glass is enhanced. Therefore, the content of each of the CaO component and the SrO component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
For the MgO component, CaO component, and SrO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

  The total content (mass sum) of the MgO component, CaO component, SrO component and BaO component is preferably 20.0% or less. Thereby, the fall of a refractive index and the raise of an Abbe number can be suppressed. Accordingly, the upper limit of the mass sum (MgO + CaO + SrO + BaO) is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%.

Y ₂ O ₃ component, _La 2 _{O 3} component and _Gd 2 _{O 3} component, when ultra containing 0%, increasing the refractive index of the glass, which is an optional component that can and improving chemical durability.
On the other hand, by suppressing the content of each of the Y ₂ O ₃ component, the La ₂ O ₃ component, and the Gd ₂ O ₃ component to 10.0% or less, an increase in the Abbe number of the glass is suppressed and devitrification resistance is maintained. Can be increased. Therefore, the content of each of the Y ₂ O ₃ component, La ₂ O ₃ component and Gd ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%. To do.
Y ₂ O ₃ component, La ₂ O ₃ component and Gd ₂ O ₃ component are Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) as raw materials ), Gd ₂ O ₃ , GdF ₃ or the like can be used.

The sum (mass sum) of the contents of the Y ₂ O ₃ component, La ₂ O ₃ component and Gd ₂ O ₃ component is preferably 15.0% or less. Thereby, the increase in Abbe number by these components can be suppressed. Therefore, the upper limit of the mass sum (Y ₂ O ₃ + La ₂ O ₃ + Gd ₂ O ₃ ) is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.

The SiO ₂ component is an optional component that increases the devitrification resistance of the glass and reduces the coloration of the glass to increase the visible light transmittance when it contains more than 0%.
On the other hand, when the content of SiO ₂ component to 10.0% or less, is suppressed a decrease in the refractive index. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance when it contains more than 0%.
However, since GeO ₂ has a high raw material price, a large amount of GeO ₂ increases the material cost. Accordingly, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably not contained.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it is contained in excess of 0%.
On the other hand, by setting the content of the TeO ₂ component to 15.0% or less, the devitrification resistance of the glass can be increased, and the coloring of the glass can be reduced to increase the visible light transmittance. Therefore, the content of the TeO ₂ component is preferably 15.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably not contained.
TeO ₂ component can use TeO ₂ or the like as a raw material.

When the ZrO ₂ component is contained in an amount of more than 0%, it is an optional component that can reduce the coloring of the glass to increase the visible light transmittance and increase the devitrification resistance.
On the other hand, by making the ZrO ₂ component 10.0% or less, a decrease in the refractive index of the glass due to excessive inclusion of the ZrO ₂ component can be suppressed. Therefore, the content of the ZrO ₂ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The ZnO component is an optional component that can increase the devitrification resistance by lowering the liquidus temperature of the glass when it contains more than 0%.
On the other hand, by making the content of the ZnO component 10.0% or less, a decrease in the refractive index of the glass and an increase in the Abbe number can be suppressed. Therefore, the content of the ZnO component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and further preferably not contained.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

When the Al ₂ O ₃ component is contained in an amount of more than 0%, it is an optional component that can increase the chemical durability of the glass and increase the viscosity during glass melting.
On the other hand, by making the content of the Al ₂ O ₃ component 10.0% or less, it is possible to weaken the devitrification tendency of the glass and suppress the decrease in the Abbe number. Therefore, the content of the Al ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably not contained.
As the Al ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like can be used as a raw material.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass when it exceeds 0%.
On the other hand, by making the Ta ₂ O ₅ component 10.0% or less, the material cost of the glass can be reduced, and the glass can be hardly devitrified. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component that can increase the visible light transmittance of the glass and degas the molten glass when it is contained in an amount of more than 0%.
On the other hand, if the amount of Sb ₂ O ₃ is too large, the Sb ₂ O ₃ component is alloyed with a melting facility (especially a noble metal such as Pt) to cause impurities to adhere to the mold. And cloudiness are easily formed. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.7%, and still more preferably 0.5%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer 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.

  Other components not described above can be added as necessary within a range not impairing the properties of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is independent of each other. Alternatively, even when contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. Therefore, it is preferable that the optical glass that transmits the wavelength in the visible range is not substantially contained.

Moreover, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with high environmental loads, it is desirable that they are not substantially contained, that is, not contained at all except for inevitable mixing.

  Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical material in recent years. When used, not only the glass manufacturing process, but also the processing process, and It is necessary to take measures for environmental measures until disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
P ₂ O ₅ component 5.0～40.0Mol% and _Nb 2 _{O 5} component 5.0~50.0mol%,
And TiO ₂ component 0 to 50.0 mol%
WO ₃ component 0-25.0 mol%
Li ₂ O component 0 to 50.0 mol%
Na ₂ O component 0～40.0Mol%
K ₂ O component 0～25.0Mol%
BaO component 0 to 20.0 mol%
B ₂ O ₃ component 0～20.0Mol%
MgO component 0 to 20.0 mol%
CaO component 0 to 25.0 mol%
SrO component 0 to 15.0 mol%
Y ₂ O ₃ component 0～7.0Mol%
La ₂ O ₃ component 0～5.0Mol%
Gd ₂ O ₃ component 0-5.0 mol%
SiO ₂ component 0 to 25.0 mol%
GeO ₂ component 0-15.0 mol%
Bi ₂ O ₃ component 0-5.0 mol%
TeO ₂ component 0 to 15.0 mol%
ZrO ₂ component 0 to 15.0 mol%
ZnO component 0 to 20.0 mol%
Al ₂ O ₃ component 0 to 15.0 mol%
Ta ₂ O ₅ component 0-3.0 mol%
Sb ₂ O ₃ component 0～1.0Mol%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range. Put in a crucible and melt in the temperature range of 1000 to 1300 ° C for 2 to 10 hours, stir and homogenize to remove bubbles, etc. It is produced by casting into a mold and slow cooling.

[Physical properties]
The optical glass of the present invention has higher dispersion (low Abbe number) while having a high refractive index.
The Abbe number (ν _d ) of the optical glass of the present invention is preferably 20, more preferably 19, still more preferably 18, and even more preferably less than 17.2. The lower limit of this Abbe number may be preferably 10, more preferably 12, and even more preferably 15. By having such a low Abbe number, for example, when combined with an optical element having a high Abbe number, high imaging characteristics and the like can be achieved.
The refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.80, and still more preferably 1.90. The upper limit of this refractive index is preferably 2.30, more preferably 2.20, and even more preferably 2.15. By having such a high refractive index, a large amount of light can be obtained even if the device is further thinned.
Therefore, by using such an optical glass having a high refractive index and high dispersion, for example, for an optical element, the degree of freedom in optical design can be expanded while achieving high imaging characteristics and the like.

The optical glass of the present invention has high thermal stability. That is, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) in the optical glass of the present invention is preferably 100 ° C., more preferably 120 ° C., and further preferably 140 ° C. Thereby, when the glass is heated to a temperature higher than the glass transition point, generation of crystal nuclei and crystal growth inside the glass are less likely to occur, so that the thermal stability of the glass is increased. Therefore, adverse effects on the optical characteristics of the optical element, such as opacification and devitrification due to crystallization of the glass when the optical glass is molded by press, can be reduced.
In the optical glass of the present invention, for example, because the Nb ₂ O ₅ content is low, the glass transition point is lowered and the crystallization start temperature is increased. Therefore, the value of ΔT can be increased. It is thought that this is one of the factors that can improve the thermal stability.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high light transmittance on the short wavelength side of visible light, and little coloring. In particular, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 450 nm, more preferably 430 nm, and even more preferably 410 nm. In the optical glass of the present invention, the shortest wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 500 nm, more preferably 480 nm, and still more preferably 460 nm. As a result, the absorption edge of the glass is positioned in the ultraviolet region or in the vicinity thereof, and the transparency of the glass with respect to light on the short wavelength side in the visible region is further enhanced, so that the glass is colored yellow or orange. Therefore, the optical glass can be preferably used as a material for an optical element that transmits visible light such as a lens.
In the optical glass of the present invention, since the meltability of the raw material is enhanced, for example, due to the low content of the Nb ₂ O ₅ component, it is possible to melt the raw material even at a low melting temperature. It is thought to be a cause.

  The optical glass of the present invention preferably has a glass transition point (Tg) of 720 ° C. or lower. Thereby, since glass softens at lower temperature, glass can be press-molded at lower temperature. Further, it is possible to extend the life of the mold by reducing oxidation of the mold used for mold press molding. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 720 ° C, more preferably 710 ° C, and still more preferably 700 ° C. The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 100 ° C, more preferably 200 ° C, and even more preferably 300 ° C. Good.

  The optical glass of the present invention preferably has high devitrification resistance during glass production (in the specification, it may be simply referred to as “devitrification resistance”). Thereby, since the fall of the transmittance | permeability by crystallization of the glass at the time of glass preparation etc. is suppressed, this optical glass can be used preferably for the optical element which permeate | transmits visible lights, such as a lens. In addition, as a scale which shows that the devitrification resistance at the time of glass preparation is high, a liquidus temperature is low, for example.

  The optical glass of the present invention preferably has good press formability. That is, the optical glass of the present invention is preferably free from devitrification and milky white before and after the reheating test (ii). This makes it difficult for devitrification and coloring to occur even in a reheating test assuming reheat press processing, so that the light transmittance of the glass is less likely to be lost. Processing can be facilitated. That is, since an optical element having a complicated shape can be produced by press molding, it is possible to realize optical element production with low production cost and high productivity.

  Here, in the reheating test (A), a test piece of 15 mm × 15 mm × 30 mm is placed on an indented refractory and placed in an electric furnace and reheated, and the transition temperature (Tg) of each sample is 150 minutes from room temperature. After raising the temperature to a temperature 80 ° C to 150 ° C higher (temperature falling into the refractory), keeping the temperature at that temperature for 30 minutes, cooling to room temperature, taking it out of the furnace, and facing the two surfaces so that they can be observed inside After polishing to a thickness of 10 mm, the polished glass sample can be visually observed.

  It should be noted that the presence or absence of devitrification and milky white before and after the reheating test (A) can be confirmed, for example, visually, and that “devitrification and milky white do not occur” means, for example, after the reheating test (A) The value obtained by dividing the transmittance of light (d-line) having a wavelength of 587.56 nm of the test piece by the d-line transmittance of the test piece before the reheating test is approximately 0.80 or more.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding was prepared from optical glass, and after performing reheat press molding on this preform, polishing was performed to prepare a glass molded body, or polishing was performed. It is possible to produce a glass molded body by performing precision press molding on a preform, or a preform molded by a known floating molding or the like. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body produced in this way is useful for various optical elements and optical designs. In particular, it is preferable to produce optical elements such as lenses, prisms, and mirrors from the optical glass of the present invention using means such as precision press molding. As a result, when used in optical devices that transmit visible light to optical elements such as cameras and projectors, the optical system in these optical devices is miniaturized while realizing high-definition and high-precision imaging characteristics. Can be achieved.

Composition, refractive index (n _d ), Abbe number (ν _d ), spectral transmittance of 70% and 5% of Examples (No. 1 to No. 27) and Comparative Example (No. A) of the present invention. Wavelength (λ ₇₀ , λ ₅ ), glass transition point (Tg), crystallization start temperature (Tx), difference between glass transition point and crystallization start temperature (ΔT), and reheating test (casting test) The results are shown in Tables 1 to 4. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glass of these Examples and Comparative Examples are used for ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc., as raw materials for each component. The high-purity raw material to be selected is weighed so as to have the composition ratios of the examples and comparative examples shown in the table, and mixed uniformly, and then put into a platinum crucible, depending on the melting difficulty of the glass composition. Melt in a temperature range of 1000 to 1300 ° C. in an electric furnace for 2 to 10 hours, stir and homogenize, blow out bubbles, etc., lower the temperature to 1250 ° C. or lower and homogenize with stirring, and then cast into a mold. The glass was produced by cooling.

  Here, the refractive index and Abbe number of the glass of an Example and a comparative example were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. In addition, as glass used for this measurement, what was processed with the annealing furnace on the annealing conditions of slow cooling fall rate -25 degrees C / hr was used.

  Moreover, the glass transition point (Tg) and crystallization start temperature (Tx) of the glass of an Example and a comparative example are measured by using a differential heat measuring apparatus (STA 409 CD made by Netchgeretebau) in a nitrogen atmosphere. Asked. Here, the sample particle size at the time of measurement was 425 to 600 μm, and the temperature was increased from 100 ° C. to 800 ° C. at a temperature increase rate of 5 ° C./min. And (DELTA) T was calculated | required from the difference of a glass transition point (Tg) and crystallization start temperature (Tx).

Moreover, the visible light transmittance | permeability of the glass of an Example and a comparative example was measured according to Japan Optical Glass Industry Association standard JOGIS02. In addition, in this invention, the presence or absence and the grade of coloring of glass were calculated | required by measuring the visible light transmittance | permeability of glass. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (transmittance). Wavelength at 70%).

  Moreover, about the glass of an Example and a comparative example, the presence or absence of devitrification and milky white before and after a reheating test was confirmed visually. Here, confirmation of devitrification and milky white before and after the reheating test is carried out by placing a test piece of 15 mm × 15 mm × 30 mm on a concave refractory and placing it in an electric furnace to reheat it to the reheating temperature. After being kept warm for 30 minutes, cooled to room temperature and taken out of the furnace, the opposing two surfaces were polished to a thickness of 10 mm so that they could be observed inside, and then visually checked for devitrification and milky white in the polished glass sample It was done by observing. At this time, devitrification and milky white do not occur when the reheating temperature is (Tg + 80 ° C. to 150 ° C.), and also when the reheating temperature is higher than (Tg + 80 ° C. to 150 ° C.) The glass in which no milky white was produced was given a “omission test” of “◯”. Moreover, although devitrification and milky white did not occur when the reheating temperature was set within a range of (Tg + 80 ° C. to 150 ° C.), the reheating temperature was more within the range of (Tg + 80 ° C. to 150 ° C.). For the glass in which devitrification or milky white was caused when the temperature was raised, the “casting test” was set to “Δ”. Moreover, when the reheating temperature was set to a specific temperature within the range of (Tg + 80 ° C. to 150 ° C.), the glass that had devitrified or milky white was given “X” as the “casting test”.

As shown in Tables 1 to 4, all of the optical glasses of the examples of the present invention had an Abbe number (ν _d ) of 20 or less, more specifically 18 or less. For this reason, it became clear that the optical glass of the Example of this invention has a low Abbe number ((nu) _d ) compared with the glass of a comparative example.

In the optical glass of the example of the present invention, the difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) is 100 ° C. or more, more specifically 130 ° C. or more. It was.
On the other hand, the glass of the comparative example was devitrified, and the thermal stability of the glass phase was low.
Therefore, it became clear that the optical glasses of the examples of the present invention all have high thermal stability.

All of the optical glasses of the examples of the present invention had a λ ₇₀ (wavelength at a transmittance of 70%) of 500 nm or less, more specifically 480 nm or less, and were within a desired range.
In addition, in all the optical glasses of the examples of the present invention, λ ₅ (wavelength at a transmittance of 5%) was 450 nm or less, more specifically, 405 nm or less, and was in a desired range.

While the optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.70 or more, more specifically 1.95 or more, this refractive index (n _d ) is 2.20 or less. Therefore, it was within the desired range.

Therefore, the optical glass of the example of the present invention has a low Abbe number (ν _d ) while having a high refractive index (n _d ) and a high transmittance for visible light. It was revealed that devitrification when the glass was reheated was also reduced.

  Moreover, the optical glass of the Example of this invention did not produce devitrification and milky white both before and after performing a reheating test (ii). Therefore, since it became clear that the optical glass of the Example of this invention did not generate | occur | produce devitrification and milky white by reheating, it is guessed that it has high press moldability.

  Furthermore, when a lens preform was formed using the optical glass of the example of the present invention, and this lens preform was molded and press-molded, various lens shapes could be stably processed.

  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 (25)

By mass%, the P ₂ O ₅ component is 23.0% or more and 40.0% or less, the Nb ₂ O ₅ component is 30.0% or more and 60.0% or less, and the content of the TiO ₂ component is more than 15.0% 30.0% or less, Li ₂ O component 0 to 5.0%, Na ₂ O component 0 to 10.0%, K ₂ O component 0 to 10.0%, mass ratio TiO ₂ / Nb ₂ O ₅ Is 0.33 or more and 1.00 or less, the sum of the content of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component and Bi ₂ O ₃ component is 63.0% or more, and the mass ratio Na ₂ O / K ₂ O is less than 1.00, has an Abbe number (ν _d ) of less than 17.2 , and has a difference ΔT between the glass transition point (Tg) and the crystallization start temperature (Tx) of 100 ° C. or more. Glass. The optical glass according to claim 1, wherein the content of the WO ₃ component is 35.0% or less by mass. The optical glass according to claim 1, wherein the mass ratio WO ₃ / P ₂ O ₅ is 0.60 or less. The optical glass according to any one of claims 1 to 3, wherein the sum of the contents of the P ₂ O ₅ component, the Nb ₂ O ₅ component, and the WO ₃ component is 60.0% or more and 80.0% or less. The optical glass according to claim 4, wherein the optical glass contains a K ₂ O component of more than 0% by mass. The optical glass according to claim 1, wherein the mass ratio P ₂ O ₅ / Na ₂ O is 3.00 or more. The optical glass according to claim 1, wherein the sum of the contents of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component is 20.0% or less. 8. The optical glass according to claim 1, wherein a mass ratio (P ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) / (Li ₂ O + Na ₂ O + K ₂ O) is 8.00 or more and 15.00 or less. % By mass
BaO component 0 to 20.0%
Bi ₂ O ₃ component 0 to 15.0%
The optical glass according to any one of claims 1 to 8. The optical glass according to claim 1, wherein a mass ratio (TiO ₂ + Bi ₂ O ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) is 0.100 or more. The optical glass according to any one of claims 1 to 10, wherein the sum of the contents of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component, Na ₂ O component and BaO component is 80.0% or less. The optical glass according to any one of claims 1 to 11, wherein a mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Na ₂ O + BaO) / (P ₂ O ₅ + K ₂ O) is 4.00 or less. The optical glass according to any one of claims 1 to 12, wherein the content of the B ₂ O ₃ component is 10.0% or less by mass. The optical glass according to any one of claims 1 to 13, wherein the sum of the contents of B ₂ O ₃ component, BaO component, Li ₂ O component, Na ₂ O component and K ₂ O component is 20.0% or less. MgO component 0% to 5.0% by mass
CaO component 0 to 10.0%
SrO component 0 to 10.0%
The optical glass according to any one of claims 1 to 14.   The optical glass according to any one of claims 1 to 15, wherein the sum of the contents of the MgO component, CaO component, SrO component and BaO component is 20.0% or less. Y ₂ O ₃ component in mass% 0 to 10.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of claims 1 to 16. 18. The optical glass according to claim 1, wherein the sum of the contents of the Y ₂ O ₃ component, the La ₂ O ₃ component, and the Gd ₂ O ₃ component is 15.0% or less. SiO ₂ component in mass% 0 to 10.0%
GeO ₂ component 0-10.0%
TeO ₂ component 0-15.0%
ZrO ₂ component 0 to 10.0%
ZnO component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of claims 1 to 18. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.70 or more and 2.20 or less. The optical glass according to any one of claims 1 to 20, wherein a wavelength (λ ₇₀ ) at which the spectral transmittance is 70% is 500 nm or less.   The optical element which uses the optical glass in any one of Claim 1 to 21 as a base material. Lens preform formed of the optical glass according to any of claims 1 21. A lens preform for mold press molding comprising the optical glass according to any one of claims 1 to 21 .   An optical element formed by molding the lens preform according to claim 23 or 24.