WO2018230124A1 - Optical glass, preform, and optical element - Google Patents

Abstract

Provided are: an optical glass which has a low temperature coefficient of the relative refractive index and can contribute to correcting the effects on imaging characteristics due to temperature change; and a preform and an optical element using the same. The optical glass comprises, in mass%, 20.0 to 40.0% of a P2O5 component, 25.0 to 50.0% of a Nb2O5 component, and 3.0 to 30.0% of a mass sum (Na2O+K2O), and has a temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) in a range of +3.0×10-6 to -10.0×10-6 (°C-1).

Description

Optical glass, preform and optical element

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

In recent years, optical elements incorporated in in-vehicle optical devices such as in-vehicle cameras and optical elements incorporated in optical devices that generate a lot of heat, such as projectors, copiers, laser printers, and broadcasting equipment, have higher temperatures. Use in the environment is increasing. In such a high temperature environment, the temperature at the time of use of the optical element constituting the optical system is likely to fluctuate greatly, and the temperature often reaches 100 ° C. or more. At this time, since the adverse effect on the imaging characteristics and the like of the optical system due to temperature fluctuation is so large that it cannot be ignored, it is required to construct an optical system in which the imaging characteristics and the like are hardly affected even by temperature fluctuation.

When constructing an optical system that does not easily affect the imaging characteristics, etc. due to temperature fluctuations, an optical element made of glass whose refractive index decreases when the temperature rises and the temperature coefficient of the relative refractive index becomes negative. The combined use of an optical element made of glass that increases the refractive index when the temperature rises and has a positive temperature coefficient of relative refractive index can correct the influence on the imaging characteristics and the like due to the temperature change. This is preferable.

Here, as a glass developed by paying attention to the temperature coefficient of the relative refractive index, for example, a glass composition represented by Patent Document 1 is known.

JP 2007-106611 A

The glass described in Patent Document 1 is a glass containing a lot of components that provide a high refractive index, and is intended to increase the temperature coefficient of the relative refractive index. On the other hand, in a glass containing a large amount of a component that provides a high refractive index, a glass having a small temperature coefficient of relative refractive index has not been obtained. However, from the viewpoint of contributing to the correction of the influence on the imaging characteristics due to the temperature change, a glass having a negative temperature coefficient of the relative refractive index and a glass having a small absolute value of the temperature coefficient of the relative refractive index are desired.

In addition, when optical design is performed, a low-refractive index low-dispersion glass material and a high-refractive index high-dispersion glass material may be joined. If the difference in the average linear thermal expansion coefficient of the glass materials combined at the time of joining becomes small, the joining becomes good. In particular, low-refractive index low-dispersion glass materials containing fluorine are known to have a large average linear thermal expansion coefficient, but there are almost no glass materials with a high average refractive index and high-dispersion glass material that have a high average linear thermal expansion coefficient. Therefore, a glass material having a large average linear thermal expansion coefficient is demanded. The glass described in Patent Document 1 has a small average linear thermal expansion coefficient, and it is difficult to say that the glass sufficiently satisfies such a requirement.

Furthermore, the optical glass according to the present invention can be manufactured at a lower cost because a glass having excellent transmittance in visible light can be obtained without going through the steps of reheating and heat treatment to remove the coloring of the glass. be able to.

The present invention has been made in view of the above problems, and the object of the present invention is to take a small value of the temperature coefficient of the relative refractive index and contribute to the correction of the influence on the imaging characteristics due to the temperature change. The object is to obtain a preform and an optical element using optical glass having an average linear thermal expansion coefficient suitable for bonding between optical glass and a low refractive index and low dispersion glass material.

In order to solve the above-mentioned problems, the present inventor has conducted earnest test research, and as a result, contains the P ₂ O ₅ component and the Nb ₂ O ₅ component, and contains a predetermined amount of the Na ₂ O component and the K ₂ O component. Thus, it was found that an inexpensive glass having a low temperature coefficient of relative refractive index can be obtained, and the present invention has been completed. Specifically, the present invention provides the following.

(1) In mass%,
P ₂ O ₅ component 20.0-40.0%,
Nb ₂ O ₅ component 25.0 to 50.0%,
Mass sum (Na ₂ O + K ₂ O) is 3.0 to 30.0%,
Containing
The temperature coefficient (40-60 ° C.) of the relative refractive index (589.29 nm) is + 3.0 × 10 ⁻⁶
Optical glass in the range of −10.0 × 10 ⁻⁶ (° C. ⁻¹ ).

(2) The optical glass as described in (1), wherein the mass sum (Na ₂ O + K ₂ O + BaO) is 10.0 to 35.0%.

(3) The optical glass according to (1) or (2), wherein an average linear thermal expansion coefficient α at 100 to 300 ° C. is 80 (10 ⁻⁷ ° C. ⁻¹ ) or more.

(4) The optical glass according to (1) to (3), which has a refractive index (n _d ) of 1.65 or more and 2.00 or less and an Abbe number (ν _d ) of 10 or more and 35 or less.

(5) A preform made of the optical glass according to any one of (1) to (4).

(6) An optical element made of the optical glass according to any one of (1) to (4).

(7) An optical device including the optical element according to (6).

According to the present invention, an optical glass that has a small temperature coefficient of relative refractive index, can contribute to correction of influence on imaging characteristics due to temperature change, and has good transmittance in visible light, and the same are used. Preforms and optical elements can be obtained at lower costs.

The optical glass of the present invention is, by mass%, 20.0% to 40.0% of P ₂ O ₅ component, 25.0% to 50.0% in total of Nb ₂ O ₅ component, Na ₂ O component And the K ₂ O component has a mass sum of 3.0% or more and 30.0% or less, and the temperature coefficient (40 to 60 ° C.) of the relative refractive index (589.29 nm) is + 3.0 × 10 ⁻⁶ to −10. Within the range of 0 × 10 ⁻⁶ (° C. ⁻¹ ).
By containing a large amount of the Na ₂ O component and the K ₂ O component, a glass material glass having a small temperature coefficient of relative refractive index and a large average linear thermal expansion coefficient can be obtained.
Therefore, although the transmittance in visible light is good, the temperature coefficient of the relative refractive index takes a small value, and it can contribute to the correction of the influence on the imaging characteristics due to the temperature change, and the bonding property with the low refractive index and low dispersion glass material In addition, it is possible to obtain an optical glass with good visible light transmittance and a preform and an optical element using the optical glass at a lower cost.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. 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. In the present specification, unless otherwise specified, the contents of the respective components are all expressed in mass% with respect to the total mass of the oxide equivalent composition. Here, the “oxide equivalent composition” is based on the assumption 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 during melting. It is the composition which described each component contained in glass by making the total mass number of production | generation oxide into 100 mass%.

<About essential and optional components>
The P ₂ O ₅ component is an essential component as a glass-forming oxide. In particular, by containing 20.0% or more of the P ₂ O ₅ component, the viscosity of the molten glass can be improved and the stability of the glass can be enhanced. Moreover, the devitrification property at the time of reheat press is made favorable. Therefore, the content of the P ₂ O ₅ component is preferably 20.0% or more, more preferably more than 21.0%, and even more preferably more than 22.0%.
On the other hand, the desired refractive index and dispersion can be maintained by setting the content of the P ₂ O ₅ component to 40.0% or less. Therefore, the content of the P ₂ O ₅ component is preferably 40.0% or less, more preferably 35.0% or less, and even more preferably less than 30.0%.
The P ₂ O ₅ component uses Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO _4, NaH ₂ PO ₄ , KH ₂ PO _4, etc. as raw materials. be able to.

The Nb ₂ O ₅ component is an essential component as a high refractive index and high dispersion component. In particular, by containing 25.0% or more of the Nb ₂ O ₅ component, the stability of the glass can be enhanced while maintaining a high refractive index and high dispersion. Therefore, the content of the Nb ₂ O ₅ component is preferably 25.0% or more, more preferably more than 28.0%, still more preferably more than 30.0%.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 50.0% or less, the average linear thermal expansion coefficient is large, and the desired refractive index and dispersion can be maintained. Therefore, the content of the Nb ₂ O ₅ component is preferably 50.0% or less, more preferably 47.0% or less.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When the Na ₂ O component is contained in an amount of more than 0%, it is an optional component that can improve the meltability of the glass raw material, improve the transmittance, and reduce the temperature coefficient of the relative refractive index. Therefore, the content of the Na ₂ O component is preferably more than 0%, more preferably more than 0.1%, still more preferably more than 0.5%, still more preferably more than 1.0%, still more preferably 1.5%. %, More preferably more than 2.0%.
In particular, when the content exceeds 10.0%, the effect of reducing the temperature coefficient of the relative refractive index is enhanced, and the meltability of the glass is also improved.
On the other hand, by making the content of the Na ₂ O component 35.0% or less, it is possible to reduce the refractive index of the glass due to excessive inclusion, chemical durability (water resistance), and devitrification, Devitrification during reheat pressing can be suppressed. Therefore, the content of the Na ₂ O component is preferably 35.0% or less, more preferably less than 30.0%, even more preferably less than 25.0%, and even more preferably less than 20.0%.
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, when contained in excess of 0%, has a large average linear thermal expansion coefficient, good transmittance, and a small temperature coefficient of relative refractive index. Therefore, the content of the K ₂ O component is preferably more than 0%, more preferably 0.5% or more, still more preferably more than 1.0%, and even more preferably more than 2.0%.
In particular, when the content exceeds 5.0%, the effect of reducing the temperature coefficient of the relative refractive index is enhanced, and the stability of the glass is also improved.
On the other hand, when the content of the K ₂ O component is 30.0% or less, the stability of the glass can be maintained and the decrease in the refractive index can be suppressed. Therefore, the content of the K ₂ O component is preferably 30.0% or less, more preferably less than 25.0%, further preferably less than 20.0%, and further preferably less than 15.0%.
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.

The BaO component is an optional component that can increase the meltability of the glass raw material, reduce the devitrification of the glass, increase the refractive index, and decrease the temperature coefficient of the relative refractive index when it contains more than 0%. In addition, among the components that provide a high refractive index, the material cost is low and the components are easily melted. Therefore, the content of the BaO component is preferably more than 0%, more preferably more than 0.1%, still more preferably more than 1.0%, still more preferably more than 2.0%.
On the other hand, by setting the content of the BaO component to 20.0% or less, the average linear thermal expansion coefficient is large, and a decrease in the refractive index of the glass due to excessive content and devitrification can be reduced. Therefore, the content of the BaO component is preferably 20.0% or less, more preferably less than 19.0%, and even more preferably less than 18.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BaF _{2 and the} like can be used as raw materials.

The TiO ₂ component is a component that can increase the refractive index of the glass, reduce the Abbe number, and can easily obtain a stable glass when it contains more than 0%. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, and even more preferably 5.0% or more.
On the other hand, by setting the content of the TiO ₂ component to 30.0% or less, the average linear thermal expansion coefficient is large, the temperature coefficient of the relative refractive index can be reduced, and devitrification due to excessive inclusion of the TiO ₂ component is reduced. It is possible to suppress a decrease in transmittance of glass with respect to visible light (particularly, a wavelength of 500 nm or less). Therefore, the content of the TiO ₂ component is preferably 30.0% or less, more preferably less than 26.0%, even more preferably less than 23.0%, and even more preferably less than 20.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The SiO ₂ component is a glass-forming oxide component that can improve the viscosity of the molten glass when it exceeds 0%. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 0.1%, still more preferably more than 0.3%.
On the other hand, when the content of the SiO ₂ component is 5.0% or less, an increase in the glass transition point can be suppressed and a decrease in the refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably 5.0% or less, more preferably 3.0% or less, and still more preferably less than 1.0%.
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.

B ₂ O ₃ component, when ultra containing 0%, is optionally component used as a glass-forming oxide which can increase the melting property of the glass.
On the other hand, by setting the content of the B ₂ O ₃ component to 5.0% or less, the temperature coefficient of the relative refractive index can be reduced, and deterioration of chemical durability can be suppressed, and devitrification during reheat pressing. Can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 5.0% or less, more preferably 3.0% or less, more preferably less than 1.5%, and still more preferably less than 1.3%.

When the WO ₃ component is contained in an amount of more than 0%, the refractive index can be increased, the Abbe number can be lowered, the glass transition point can be lowered, and the loss can be reduced while reducing the coloration of the glass by other components that bring about a high refractive index. It is an optional component that can reduce see-through.
On the other hand, by setting the content of the WO ₃ component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced, and devitrification during reheat pressing can be suppressed. In addition, the visible light transmittance can be increased by reducing the coloring of the glass by the WO ₃ component. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 9.0%, even more preferably less than 8.0%, still more preferably less than 6.5%, still more preferably 5. It may be less than 0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

When the ZnO component is contained in an amount of more than 0%, the ZnO component is an optional component that enhances the meltability of the raw material, promotes defoaming from the melted glass, and enhances the stability of the glass. It is also a component that can lower the glass transition point and improve chemical durability.
On the other hand, by making the content of the ZnO component less than 5.0%, the temperature coefficient of the relative refractive index can be reduced, the expansion due to heat can be reduced, the decrease in the refractive index can be suppressed, and the excessive viscosity can be reduced. Devitrification due to the reduction can be reduced. Therefore, the content of the ZnO component is preferably less than 5.0%, more preferably less than 4.0%, further preferably less than 2.0%, more preferably less than 1.0%, and still more preferably 0.5%. It may be less than%. Moreover, it is not necessary to contain a ZnO component.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can increase the refractive index of the glass and reduce devitrification when it contains more than 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.
On the other hand, by setting the content of the ZrO ₂ component to 5.0% or less, the temperature coefficient of the relative refractive index can be reduced, and devitrification due to excessive inclusion of the ZrO ₂ component can be reduced. Therefore, the content of the ZrO ₂ component is preferably 5.0% or less, more preferably 3.0% or less, still more preferably less than 1.0%, and even more preferably less than 0.5%. Further, the ZrO ₂ component may not be contained.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The MgO component, CaO component, and SrO component are optional components that can adjust the refractive index, meltability, and devitrification resistance of the glass when the content exceeds 0%.
On the other hand, by setting the contents of the MgO component, the CaO component and the SrO component to 5.0% or less, a decrease in the refractive index can be suppressed, and devitrification due to excessive inclusion of these components can be reduced. Accordingly, the contents of the MgO component, CaO component and SrO component are each preferably 5.0% or less, more preferably 3.5% or less, and even more preferably less than 2.0%.

The Li ₂ O component is an optional component that can improve the meltability of the glass and lower the glass transition point.
On the other hand, by reducing the content of the Li ₂ O component, it is difficult to lower the refractive index of the glass, and devitrification of the glass and reheat press can be reduced. Therefore, the content of the Li ₂ O component is preferably 5.0% or less, more preferably less than 3.0%, further preferably 1.0% or less, and further preferably less than 0.5%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can improve the devitrification resistance of the molten glass when the content exceeds 0%.
On the other hand, by setting the content of the Al ₂ O ₃ component or the Ga ₂ O ₃ component to 10.0% or less, the liquidus temperature of the glass can be lowered to increase the devitrification resistance. Therefore, the content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably 1.%. It may be less than 0%.
Al ₂ O ₃ component is a raw material as _{Al 2 O 3, Al (OH} ) can be used 3, AlF _3, etc., _Ga 2 _{O 3} may be used as component _Ga 2 _{O 3} or the like as raw materials.

The Sb ₂ O ₃ component is an optional component that can degas the molten glass when it contains more than 0%.
On the other hand, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, it is possible to suppress a decrease in transmittance in the short wavelength region of the visible light region, solarization of glass, and a decrease in internal quality. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, more preferably less than 0.5%, more preferably less than 0.2%, and even more preferably less than 0.1%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

The total content of the Na ₂ O component and the K ₂ O component is preferably 3.0% or more. Thereby, it is possible to easily obtain a glass having a small temperature coefficient of relative refractive index, a large average linear thermal expansion coefficient, and a good transmittance. Therefore, the mass sum (Na ₂ O + K ₂ O) is preferably 3.0% or more, more preferably more than 4.0%, more preferably more than 5.0%, and still more preferably more than 6.0%.
On the other hand, by setting the total content to 30.0% or less, deterioration of the chemical durability and reduction of the refractive index of the glass due to excessive content can be suppressed. Accordingly, the mass sum (Na ₂ O + K ₂ O) is preferably 30.0% or less, more preferably less than 25.0%, and even more preferably less than 23.0%.

The total content of the Na ₂ O component, K ₂ O component and BaO component is preferably 10.0% or more. Thereby, it is easy to obtain a glass having a small temperature coefficient of relative refractive index.
Accordingly, the mass sum (Na ₂ O + K ₂ O + BaO) is preferably 10.0% or more, more preferably more than 12.0%, more preferably more than 14.0%, more preferably more than 16.0%, even more preferably Is over 17.5%.
On the other hand, by making this total content less than 35.0%, it is possible to suppress deterioration of chemical durability, reduction of the refractive index of glass due to excessive inclusion, and reduction of devitrification during reheat pressing. Accordingly, the mass sum (Na ₂ O + K ₂ O + BaO) is preferably 35.0%, more preferably 33.0% or less, and even more preferably less than 30.0%.

The total content of the Nb ₂ O ₅ component and the TiO ₂ component is preferably 30.0% or more. As a result, the temperature coefficient of the relative refractive index can be reduced while maintaining a high refractive index.
Accordingly, the mass sum (Nb ₂ O ₅ + TiO ₂ ) is preferably 30.0% or more, more preferably 35.0% or more, and further preferably 40.0% or more.
On the other hand, by setting the mass sum (Nb ₂ O ₅ + TiO ₂ ) to 65.0% or less, the liquidus temperature can be lowered and stable glass can be obtained. Accordingly, the mass sum (Nb ₂ O ₅ + TiO ₂ ) is preferably 65.0% or less, more preferably 63.0% or less, and even more preferably 60.0 or less.

The ratio of the Na ₂ O component, the K ₂ O component and the BaO component to the total content of the B ₂ O ₃ component and the TiO ₂ component is preferably more than 0.5. Thereby, the temperature coefficient of relative refractive index can be reduced and the average linear thermal expansion coefficient can be increased. Therefore, the mass ratio (Na ₂ O + K ₂ O + BaO) / (B ₂ O ₃ + TiO ₂ ) is preferably more than 0.5, more preferably more than 0.7, and still more preferably more than 1.0.
On the other hand, by setting the mass ratio (Na ₂ O + K ₂ O + BaO) / (B ₂ O ₃ + TiO ₂ ) to less than 5.5, a glass with good reheat press can be obtained while maintaining the desired refractive index and transmittance. Obtainable. Therefore, the mass ratio (Na ₂ O + K ₂ O + BaO) / (B ₂ O ₃ + TiO ₂ ) is preferably less than 5.5, more preferably less than 5.0, and even more preferably less than 4.8.

The sum (mass sum) of the content of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is more than 0%, so that the refractive index of the glass is increased. The meltability and devitrification resistance can be increased. Therefore, the lower limit of the sum (mass sum) of the RO component contents is preferably more than 0%, more preferably more than 0.5%, and still more preferably more than 1.0%. On the other hand, by setting the RO component to 30.0% or less, the average linear thermal expansion coefficient is large, and the glass can be reduced in refractive index and devitrification due to excessive inclusion. Therefore, the sum of the RO component contents (mass sum) is preferably 30.0% or less, more preferably 25.0% or less, and still more preferably 20.0% or less.

When the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ component and Ta ₂ O ₅ component are contained in excess of 0%, the refractive index of the glass can be increased and the loss resistance can be increased. It is an optional component that can increase the permeability.
On the other hand, by making the content of La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ component and Ta ₂ O ₅ component 5.0% or less, the raw material of optical glass The cost can be reduced, and the melting temperature of the raw material is lowered, and the energy required for melting the raw material is reduced. Therefore, the manufacturing cost of the optical glass can also be reduced. Therefore, the content of each of these components is preferably 5.0% or less, more preferably less than 3.0%, more preferably less than 2.0%, and even more preferably less than 1.0%.

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, the raw material price of GeO ₂ is high, and the production cost increases when the content is large. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index, lower the Abbe number, and lower the glass transition point when it contains more than 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 5.0% or less, the liquidus temperature of the glass can be lowered to increase the devitrification resistance. Therefore, the content of the Bi ₂ O ₃ component is preferably 5.0% or less, more preferably less than 3.0%, and even more preferably less than 1.0%. In particular, it is preferably not contained from the viewpoint of obtaining a glass with good transmittance.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, TeO ₂ has a problem that it can be alloyed with platinum when melting a glass raw material in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.
TeO ₂ component can use TeO ₂ or the like as a raw material.

When the SnO ₂ component is contained in an amount of more than 0%, the SnO ₂ component is an optional component that can be refined by reducing the oxidation of the molten glass and can increase the visible light transmittance of the glass.
On the other hand, when the content of the SnO ₂ component is 3.0% or less, the coloring of the glass due to the reduction of the molten glass and the devitrification of the glass can be reduced. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, more preferably less than 1.0%, further preferably less than 0.5%, and further preferably less than 0.1%.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.
The components for clarifying and defoaming the glass are not limited to the above-described Sb ₂ O ₃ component and SnO ₂ component, and well-known fining agents, defoaming agents or combinations thereof in the field of glass production are used. be able to.

The F component is an optional component that can increase the glass Abbe number, lower the glass transition point, and improve the devitrification resistance when it is contained in excess of 0%.
However, when the content of the F component, that is, the total amount of F substituted for a part or all of one or more oxides of each of the above metal elements exceeds 10.0%, F Since the volatilization amount of the component increases, it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass. In addition, the Abbe number rises more than necessary.
Therefore, the content of the F component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.
The F component can be contained in the glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

SiO ₂ component, Al ₂ O ₃ component and ZnO component with respect to the total content of B ₂ O ₃ component and Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) The content ratio is preferably 15.0 or less. By reducing this ratio, deterioration of meltability can be suppressed.
Therefore, the mass ratio (SiO ₂ + Al ₂ O ₃ + ZnO) / (B ₂ O ₃ + Rn ₂ O) is preferably 15.0 or less, more preferably 12.0 or less, more preferably 10.0 or less, more preferably Is 8.0 or less, more preferably 6.0 or less, and still more preferably less than 5.0.
On the other hand, the mass ratio (SiO ₂ + Al ₂ O ₃ + ZnO) / (B ₂ O ₃ + Rn ₂ O) can be greater than zero. Thereby, the temperature coefficient of relative refractive index can be reduced and the average linear thermal expansion coefficient can be increased. Therefore, the mass ratio (SiO ₂ + Al ₂ O ₃ + ZnO) / (B ₂ O ₃ + Rn ₂ O) is preferably more than 0, more preferably more than 1.0, and still more preferably more than 2.0.

Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K), the sum (mass sum) of the content is more than 1.0%, the relative refractive index And the average linear thermal expansion coefficient can be increased. Accordingly, the sum (mass sum) of the contents of the Rn ₂ O component is preferably more than 1.0%, more preferably more than 1.5%, and still more preferably more than 2.0%.
On the other hand, by setting the sum to 30.0% or less, devitrification due to a decrease in the viscosity of the glass can be reduced while maintaining a desired refractive index and dispersion. Therefore, the sum (mass sum) of the contents of the Rn ₂ O component is preferably 30.0% or less, more preferably less than 25.0%, and even more preferably less than 23.0%.

The optical glass of the present invention preferably contains two or more components among the above-mentioned Rn ₂ O components. This eliminates the need for a reheating and heat treatment step to reduce the temperature coefficient of the relative refractive index and improve the transmittance. In particular, as the Rn 2 _O component, to contain two or more components containing Na 2 _O component and K _{2 O} component is a large average linear thermal expansion coefficient, the transmittance was improved, the temperature coefficient of the relative refractive index Is preferable in that it can be reduced.

The sum (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, Gd, Y, Yb, and Lu) is preferably 5.0% or less.
Thereby, it is possible to obtain a glass having excellent devitrification resistance and good transmittance. Therefore, the sum (mass sum) of the contents of the Ln ₂ O ₃ component is preferably 5.0% or less, more preferably 3.5% or less, and still more preferably less than 2.0%.

<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 can be added as necessary within the range not impairing the characteristics 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. Or, even when it is 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. .

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 be refrained from being used as a harmful chemical material in recent years, and not only in the glass manufacturing process, but also in the processing process and disposal after commercialization. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, as the raw materials for the above components, high purity raw materials used for ordinary optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc. Mix uniformly so as to be within the range of the content of metal, put the prepared mixture into a platinum crucible, and melt in a temperature range of 1000-1500 ° C for 1-10 hours in an electric furnace depending on the difficulty of melting the glass raw material After stirring and homogenizing, the temperature is lowered to an appropriate temperature, cast into a mold, and slowly cooled.

<Physical properties>
The optical glass of the present invention preferably has a high refractive index and a low Abbe number (high dispersion).
In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.65 or more, more preferably 1.67 or more, and further preferably 1.69 or more. This refractive index (n _d ) is preferably 2.00 or less, more preferably 1.98 or less, still more preferably 1.96 or less, and even more preferably 1.95 or less.
Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 10.0 or more, more preferably 13.0 or more, further preferably 15.0 or more, and further preferably 17.0 or more. The Abbe number (ν _d ) is preferably 35.0 or less, more preferably 34.0 or less, still more preferably 32.0 or less, and even more preferably 30.0 or less.
By having such a high refractive index, a large amount of light can be obtained even if the optical element is thinned. Further, by having such high dispersion, the focal point can be appropriately shifted depending on the wavelength of light when used as a single lens. Therefore, for example, when an optical system is configured in combination with an optical element having low dispersion (high Abbe number), it is possible to achieve high imaging characteristics and the like by reducing aberrations as a whole of the optical system.
As described above, the optical glass of the present invention is useful in optical design. Particularly when an optical system is configured, the optical system can be downsized while achieving high imaging characteristics and the like. The degree of freedom can be expanded.

The optical glass of the present invention has a low temperature coefficient (dn / dT) of relative refractive index.
More specifically, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably + 3.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably + 1.5 × 10 ⁻⁶ ° C. ⁻¹ , more preferably The upper limit value is + 1.0 × 10 ⁻⁶ ° C. ⁻¹ , and this upper limit value or a lower value (minus side) can be taken.
On the other hand, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably −10.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably −8.0 × 10 ⁻⁶ ° C. ⁻¹ , more preferably − 7.0 × 10 ⁻⁶ ° C. ⁻¹ is set as the lower limit value, and this lower limit value or a value higher (plus side) than it can be taken.
Among these, many glasses having a low temperature coefficient of relative refractive index are present as glasses having a refractive index (n _d ) of 1.65 or more and an Abbe number (ν _d ) of 10 or more and 35 or less. Therefore, it is possible to expand the options for correction such as image formation deviation due to temperature change, and to make the correction easier. Therefore, by setting the temperature coefficient of the relative refractive index in such a range, it is possible to contribute to correction of image formation shift due to a temperature change.
The temperature coefficient of the relative refractive index of the optical glass of the present invention is the temperature coefficient of the refractive index (589.29 nm) in air at the same temperature as the optical glass, and when the temperature is changed from 40 ° C. to 60 ° C. Of change per 1 ° C. (° C. ⁻¹ ).

In the optical glass of the present invention, the average linear thermal expansion coefficient α at 100 to 300 ° C. is preferably 80 (10 ⁻⁷ ° C. ⁻¹ ) or more. That is, the average linear thermal expansion coefficient α at 100 to 300 ° C. of the optical glass of the present invention is preferably 80 (10 ⁻⁷ ° C. ⁻¹ ) or more, more preferably 85 (10 ⁻⁷ ° C. ⁻¹ ) or more, more preferably Is 90 (10 ⁻⁷ ° C. ⁻¹ ) or more.
In general, if the average linear thermal expansion coefficient α is large, cracks are likely to occur when glass is processed. Therefore, it is desirable that the average linear thermal expansion coefficient α is small. On the other hand, in terms of joining in combination with a glass material having a low temperature coefficient of relative refractive index and a large average linear thermal expansion coefficient α, the glass material and the average linear thermal expansion coefficient α are the same or approximate. It is desirable.
Among these, glass having a refractive index (n _d ) of 1.65 or more and an Abbe number (ν _d ) of 10 or more and 35 or less has few glass materials having a large average linear thermal expansion coefficient α, and has a low refractive index. When used in combination with a low dispersion glass material, it is more useful that the average linear thermal expansion coefficient α has a large value as in the present invention.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high transmittance of light on the short wavelength side of visible light, and thereby less coloring.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the shortest wavelength (λ ₈₀ ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 460 nm or less, more preferably 450 nm or less, and even more preferably. Is 440 nm or less.
In the optical glass of the present invention, the shortest wavelength (λ ₇₀ ) having a spectral transmittance of 70% in a 10 mm thick sample is preferably 430 nm or less, more preferably 420 nm or less, and even more preferably 410 nm or less.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) having a spectral transmittance of 5% in a 10 mm thick sample is preferably 400 nm or less, more preferably 390 nm or less, and even more preferably 380 nm or less.
As a result, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of, for example, polishing or molding press molding such as reheat press molding or precision press molding. In other words, optical glass is subjected to mechanical processing such as grinding and polishing to produce a glass molded body, or a preform for mold press molding is produced from optical glass, and reheat press molding is performed on this preform. Then, polishing is performed to produce a glass molded body, or precision preforming is performed on a preform formed by polishing or a preform formed by known floating molding, etc., to form a glass molded body. Can be produced. In addition, the means for producing the glass molded body is not limited to these means.

Thus, the optical glass of the present invention is useful for various optical elements and optical designs. Among these, it is particularly preferable to form a preform from the optical glass of the present invention, and perform reheat press molding, precision press molding or the like using this preform to produce an optical element such as a lens or a prism. As a result, a preform having a large diameter can be formed, so that it is possible to realize high-definition and high-precision imaging characteristics and projection characteristics when used in an optical apparatus while increasing the size of the optical element.

The glass molded body made of the optical glass of the present invention can be used for applications of optical elements such as lenses, prisms, mirrors, etc., and typically tends to become high temperature such as in-vehicle optical devices, projectors, and copiers. Can be used for equipment.

Compositions of Examples (No. 1 to No. 51) and Comparative Examples (No. A, B) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), and relative refractive index of these glasses Tables 1 to 8 show the results of temperature coefficient (dn / dT), average linear thermal expansion coefficient (100 to 300 ° C.), and transmittance (λ _80, λ _70, λ ₅ ). The following examples are merely for illustrative purposes and are not limited to these examples.

The glasses of the examples and comparative examples of the present invention are used for ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds corresponding to the raw materials of the respective components. A high-purity raw material is selected, weighed so as to have the composition ratio of each example shown in the table, and mixed uniformly, and then put into a platinum crucible, which is 800 in an electric furnace according to the difficulty of melting the glass raw material. It was melted at a temperature range of ˜1300 ° C. for 1 to 10 hours, homogenized with stirring, cast into a mold or the like, and slowly cooled.

The refractive index (n _d ) and Abbe number (ν _d ) of the glass of the example and the comparative example are shown as measured values with respect to the d-line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is the refractive index of the d line, the refractive index (n _F ) for the F lamp (486.13 nm) of the hydrogen lamp, and the refractive index (n _C ) for the C line (656.27 nm). Was calculated from the equation of Abbe number (ν _d ) = [(n _d −1) / (n _F −n _C )].

The temperature coefficient (dn / dT) of the relative refractive index of the glass of Examples and Comparative Examples is a method described in Japanese Optical Glass Industry Association Standard JOGIS18-2008 “Measurement Method of Temperature Coefficient of Refractive Index of Optical Glass” The value of the temperature coefficient of the relative refractive index at 40 to 60 ° C. for light having a wavelength of 589.29 nm was measured by the interferometry.

In addition, the average linear thermal expansion coefficient (100-300 ° C.) of the glass of the example and the comparative example is the temperature and the elongation of the sample according to Japan Optical Glass Industry Association Standard JOGIS08-2003 “Measurement Method of Thermal Expansion of Optical Glass”. From the thermal expansion curve obtained by measuring the relationship of.

The transmittance of the glass of the example was measured according to Japan Optical Glass Industry Association Standard JOGIS02-2003. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. Specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₈₀ (wavelength at 80% transmittance), λ ₇₀ (transmittance). (Wavelength at 70%) and λ ₅ (wavelength at 5% transmittance) were determined.

The optical glass of the example of the present invention contains a P ₂ O ₅ component and a Nb ₂ O ₅ component, and contains a predetermined amount of a Na ₂ O component and a K ₂ O component, so that the temperature coefficient of the relative refractive index is small. An inexpensive glass with a value can be obtained.

As shown in the table, in the optical glasses of the examples, the temperature coefficient of the relative refractive index is within the range of + 1.0 × 10 ⁻⁶ to −10.0 × 10 ⁻⁶ (° C. ⁻¹ ). Specifically, it was within the range of + 3.0 × 10 ⁻⁶ to −10.0 × 10 ⁻⁶ (° C. ⁻¹ ), and was within the desired range.

Further, the optical glasses of the examples all had a refractive index (n _d ) of 1.65 or more, and were within a desired range. Further, the optical glasses of the examples of the present invention all had an Abbe number (ν _d ) in the range of 10 or more and 35 or less, and were in a desired range.

The optical glasses of the examples all had an average linear thermal expansion coefficient (100-300 ° C.) of 80 (10 ⁻⁷ ° C. ⁻¹ ) or more.

The optical glass of the example had a transmittance (λ ₈₀ ) of 460 nm or less, a transmittance (λ ₇₀ ) of 430 nm or less, and a transmittance (λ ₅ ) of 400 nm or less.

Further, the optical glass of the example formed a stable glass, and devitrification hardly occurred at the time of glass production. On the other hand, the glass of Comparative Example A did not vitrify because devitrification occurred.

Accordingly, the optical glass of the example has a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, and takes a value with a small temperature coefficient of relative refractive index, and can be obtained at a lower material cost. It became clear. Therefore, the optical glass of the embodiment of the present invention contributes to miniaturization of an optical system such as an in-vehicle optical device or a projector used in a high temperature environment, and contributes to correction of a shift in imaging characteristics due to a temperature change. It is inferred that

Furthermore, a glass block was formed using the optical glass of the example of the present invention, and this glass block was ground and polished to be processed into the shape of a lens and a prism. As a result, it was possible to stably process into various lens and prism shapes.

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 (7)

% By mass
P ₂ O ₅ component 20.0-40.0%,
Nb ₂ O ₅ component 25.0 to 50.0%,
Mass sum (Na ₂ O + K ₂ O) is 3.0 to 30.0%,
Containing
The temperature coefficient (40-60 ° C.) of the relative refractive index (589.29 nm) is + 3.0 × 10 ⁻⁶
Optical glass in the range of −10.0 × 10 ⁻⁶ (° C. ⁻¹ ). _2. The optical glass according to claim 1, wherein the mass sum (Na ₂ O + K ₂ O + BaO) is 10.0 to 35.0%. 3. The optical glass according to claim 1, wherein an average linear thermal expansion coefficient α at 100 to 300 ° C. is 80 (10 ⁻⁷ ° C. ⁻¹ ) or more. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.65 or more and 2.00 or less and an Abbe number (ν _d ) of 10 or more and 35 or less. A preform comprising the optical glass according to claim 1. An optical element made of the optical glass according to claim 1. An optical apparatus comprising the optical element according to claim 6.