JP2017154963A - Optical glass, preform and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical glass having a small partial dispersion ratio (θg,F) and weather resistance in the rank of Class 1 or 2 by a surface method, while having desired ranges of a refractive index (n) and an Abbe number (ν).SOLUTION: The optical glass contains, by mass% in terms of oxide composition, a SiOcomponent by 20.0 to 60.0%, a NbOcomponent by 15.0 to 50.0%, and a KO component by over 0.1 to 15.0%, and has a partial dispersion ratio (θg,F) satisfying a relationship of (-0.00256×νd+0.637)≤(θg,F)≤(-0.00256×νd+0.684) together with an Abbe number (ν), and weather resistance in the rank of Class 1 or 2 by a surface method.SELECTED DRAWING: Figure 2

Description

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

  Optical systems such as digital cameras and video cameras, although large and small, contain blurs called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration. In particular, the chromatic aberration is strongly dependent on the material characteristics of the lens used in the optical system.

  In general, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens. However, this combination can only correct aberrations in the red region and the green region, and remains in the blue region. This blue region aberration that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, it is necessary to perform an optical design in consideration of the trend of the g-line (435.835 nm) in the blue region. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics to be noticed in the optical design. In the optical system combining the low dispersion lens and the high dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low dispersion side lens, and the partial dispersion ratio ( By using an optical material having a small θg, F), the secondary spectrum is corrected well.

The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis. It is represented by a straight line connecting two points and is called a normal line (see FIG. 1). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA, Inc., and the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7. Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

In recent years, glass having an Abbe number (ν _d ) of 30 or more and 47 or less is often used as an optical material having a small partial dispersion ratio (θg, F) due to needs in optical design. Here, as a conventional glass having an Abbe number (ν _d ) of 30 or more and 47 or less, for example, optical glasses as shown in Patent Documents 1 and 2 are known.

On the other hand, in an optical material having a small partial dispersion ratio (θg, F), due to components (Nb ₂ O ₅ component, B ₂ O ₃ component, Li ₂ O component) contained in order to obtain excellent optical properties, There is a tendency for chemical durability to deteriorate. In these optical glasses, spiders and interference films may form on the glass surface due to polishing liquid, water vapor in the atmosphere, carbon dioxide gas, etc. during processing and storage. It is called “blue discoloration” and becomes a problem as a serious defect when used as a lens.
Furthermore, optical glasses that do not cause burns are required because they are often used in various environments such as in-vehicle lenses and interchangeable lenses used in recent years.

JP 2002-029777 A Japanese Patent Laid-Open No. 2003-054983

  However, the glass disclosed in Patent Document 1 does not have a small partial dispersion ratio, and is not sufficient for use as a lens for correcting the secondary spectrum. It cannot be said that there is. Moreover, although the glass disclosed in Patent Document 2 has a low glass transition point (Tg), the stability of the glass is poor, and chemical durability, particularly surface method weather resistance, is not sufficient.

The present invention has been made in view of the above-mentioned problems. The object of the present invention is to achieve a partial dispersion ratio (n _d ) and an Abbe number (ν _d ) within a desired range. The object is to obtain an optical glass having a small θg, F) and good chemical durability, in particular, surface method weather resistance.

As a result of intensive studies and studies to solve the above-mentioned problems, the inventors of the present invention desired that the glass containing the SiO ₂ component and the Nb ₂ O ₅ component contains the K ₂ O component as an essential component. It is found that a glass having a high refractive index, a low Abbe number (high dispersion) and a low partial dispersion ratio in the range of 5 and a glass having good chemical durability, particularly surface method weather resistance, can be obtained. It came to complete.

(1) In mass% of oxide equivalent composition,
20.0 to 60.0% of SiO ₂ component,
10.0-50.0% of Nb ₂ O ₅ component,
K ₂ O component exceeds 0.1 to 15.0%
Contains,
Between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ), (−0.00256 × ν _d +0.637) ≦ (θg, F) ≦ (−0.00256 × ν _d +0.684) )
Optical glass whose surface method weather resistance is class 1 or 2.

(2) In mass% of oxide equivalent composition,
TiO ₂ component 0 to 10.0%
B ₂ O ₃ component 0 to 20.0%
Li ₂ O component 0 to 15.0%
Na ₂ O component 0 to 15.0%
And
The optical glass according to (1), wherein a mass sum of an Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 5.0% or more and 30.0% or less. .

(3) In mass% of oxide equivalent composition,
ZrO ₂ component 0 to 20.0%
MgO component 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
ZnO component 0 to 25.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
WO ₃ components 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0-5.0%
SnO ₂ component 0-5.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to (1) or (2).

(4) SiO ₂ component and _Nb 2 _{O 5} the sum of the content of the component is 50.0 percent (1) to (3) any description of the optical glass.

(5) The mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 30.0% or less,
Any one of (1) to (4), wherein the mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd and Yb) is 15.0% or less The optical glass described.

(6) The optical glass according to any one of (1) to (4), having a refractive index (n _d ) of 1.60 to 1.78 and an Abbe number (ν _d ) of 28 to 47.

  (7) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (5).

  (8) An optical element made of the optical glass according to any one of (1) to (5).

According to the present invention, while the refractive index (n _d ) and Abbe number (ν _d ) are within a desired range, a high refractive index within the desired range, a low Abbe number (high dispersion), and a low partial dispersion ratio. An optical glass with good chemical durability can be obtained while keeping the partial dispersion ratio (θg, F) small.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the Example of this application.

The optical glass of the present invention is the mass% of the oxide equivalent composition, the SiO ₂ component is 20.0 to 60.0%, the Nb ₂ O ₅ component is 10.0 to 50.0%, and the K ₂ O component is 0. .1 to more than 15.0%, and the partial dispersion ratio (θg, F) is between the Abbe number (ν _d ) and (−0.00256 × ν _d +0.637) ≦ (θg, F) ≦ The relationship of (−0.00256 × ν _d +0.684) is satisfied, and the surface method weather resistance is class 1 or 2.
In a glass containing SiO ₂ component, Nb ₂ O ₅ component and K ₂ O component, a glass having a high refractive index and a low Abbe number (high dispersion) within a desired range and a low partial dispersion ratio can be obtained. In particular, by containing a K ₂ O component, it becomes easy to adjust a desired optical constant, and it is possible to reduce the occurrence of burns while keeping the partial dispersion ratio (θg, F) small.
Therefore, while having the desired high refractive index (n _d ) and low Abbe number (ν _d ), the partial dispersion ratio (θg, F) is small and useful for reducing chromatic aberration of the optical system, In particular, an optical glass having good surface method weather resistance can be obtained.

  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 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. 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>
Since the SiO ₂ component promotes stable glass formation and can lower the liquidus temperature, it is an essential component for reducing devitrification (generation of crystal) that is not preferable for optical glass.
In particular, when the content of the SiO ₂ component is 20.0% or more, a glass excellent in devitrification resistance can be obtained without significantly increasing the partial dispersion ratio. Moreover, chemical durability can be improved and devitrification and coloring can be reduced. Accordingly, the content of the SiO ₂ component is preferably 20.0%, more preferably 23.0%, further preferably 25.0%, and further preferably 27.0%.
On the other hand, when the content of the SiO ₂ component is 60.0% or less, the refractive index is hardly lowered, so that a desired high refractive index can be easily obtained, and an increase in the partial dispersion ratio can be suppressed. Moreover, the fall of the meltability of a glass raw material can be suppressed by this. Accordingly, the content of SiO ₂ component is preferably 60.0%, more preferably 55.0%, further preferably 50.0%, more preferably 48.0%, still more preferably 45.0%, most preferably Preferably, the upper limit is 43.0%.
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 Nb ₂ O ₅ component is an essential component that can increase the refractive index, reduce the Abbe number and the partial dispersion ratio, and increase the resistance to devitrification.
In particular, by setting the content of the Nb ₂ O ₅ component to 10.0% or more, the refractive index is increased to the target optical constant, and the anomalous dispersion is reduced by adjusting the component within the range of the present invention. can do. Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0%, more preferably 15.0%, still more preferably 20.0%, and further preferably 23.0%.
On the other hand, by the content of _Nb 2 _{O 5} component below 50.0%, thereby reducing the material cost of the glass. Further, to suppress an increase in melting temperature at the time of glass production, it and reduce the devitrification due to excessive content of Nb ₂ O ₅ component. Furthermore, the deterioration of the chemical durability of the glass can also be improved. Therefore, the content of the Nb ₂ O ₅ component is preferably 50.0%, more preferably 45.0%, still more preferably 43.0%, and even more preferably 41.5%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The K ₂ O component is an essential component that can improve chemical durability.
In particular, when the content of the K ₂ O component exceeds 0.1%, the burn in the glass can be effectively improved. Therefore, the content of the K ₂ O component is preferably more than 0.1%, more preferably more than 0.3%, and the original content is preferably more than 0.5%.
On the other hand, by setting the content of the K ₂ O component to 15.0% or less, an increase in the partial dispersion ratio can be suppressed, devitrification can be reduced, and chemical durability can hardly be deteriorated. Therefore, the content of the K ₂ O component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably less than 8.0%.
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 TiO ₂ component is an optional component that increases the refractive index, decreases the Abbe number, and increases the devitrification resistance when the content is more than 0%.
On the other hand, when the content of the TiO ₂ component is 10.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. In addition, this makes it difficult to increase the partial dispersion ratio, so that a desired low partial dispersion ratio close to the normal line can be easily obtained. Moreover, this can suppress deterioration of chemical durability. Therefore, the content of the TiO ₂ component is preferably 10.0% or less, more preferably 5.0% or less, still more preferably less than 3.0%, and most preferably less than 1.0%. In particular, from the viewpoint of reducing the anomalous dispersion of the glass, it is desirable that the glass is not substantially contained.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

When the B ₂ O ₃ component exceeds 0%, stable glass formation can be promoted and the liquidus temperature can be lowered, so that the devitrification resistance can be enhanced and the meltability of the glass raw material can be enhanced. It is an optional component. Accordingly, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably more than 0.1%, still more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably 5. It may be more than 0%.
On the other hand, when the content of the B ₂ O ₃ component is 20.0% or less, a decrease in the refractive index can be suppressed and an increase in the partial dispersion ratio can be suppressed. Furthermore, the chemical durability of the glass can also be improved. Therefore, the content of the B ₂ O ₃ component is preferably 20.0%, more preferably 18.0%, still more preferably 15.0%, and still more preferably 12.0%.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The Li ₂ O component is an optional component that can lower the partial dispersion ratio, improve the transmittance, lower the liquidus temperature, and increase the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.
On the other hand, by setting the content of the Li ₂ O component to 15.0% or less, a decrease in refractive index can be suppressed, chemical durability can hardly be deteriorated, and devitrification due to excessive inclusion can be reduced.
Therefore, the content of the Li ₂ O component is preferably 15.0% or less, more preferably 13.0% or less, still more preferably less than 10.0%, and even more preferably less than 8.0%.
For the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The Na ₂ O component is an optional component that can lower the partial dispersion ratio, lower the liquidus temperature, and improve the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the Na ₂ O component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.
On the other hand, by setting the content of the Na ₂ O component to 15.0% or less, a decrease in the refractive index can be suppressed, chemical durability can hardly be deteriorated, and devitrification due to excessive content can be reduced.
Therefore, the content of the Na ₂ O component is preferably 15.0% or less, more preferably 13.0% or less, still more preferably less than 10.0%, and even more preferably less than 8.0%.
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 sum (mass sum) of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 5.0% or more. The meltability can be increased and the glass transition point can be lowered. Therefore, the content of the Rn ₂ O component is preferably 5.0%, more preferably 8.0%, still more preferably 10.0%, and even more preferably 12.0%.
On the other hand, by setting the Rn ₂ O component to 30.0% or less, the viscosity in the glass can be hardened and the moldability can be improved. Accordingly, the upper limit is preferably 30.0%, more preferably 25.0%, still more preferably 20.0%, and even more preferably 17.0%.

The ZrO ₂ component is an optional component that can increase the refractive index and Abbe number of the glass, lower the partial dispersion ratio, and increase the devitrification resistance when it contains more than 0%. Moreover, devitrification and coloring can be reduced. Therefore, the content of the ZrO ₂ component is preferably more than 1.0%, more preferably more than 3.0%, more preferably more than 5.0%.
On the other hand, by setting the content of the ZrO ₂ component to 20.0% or less, devitrification can be reduced, and more uniform glass can be easily obtained. Therefore, the content of the ZrO ₂ component is preferably 20.0%, more preferably 18.0%, still more preferably 15.0%, still more preferably 13.0%, and even more preferably 10.0%. And
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The MgO component is an optional component that can lower the melting temperature of the glass when it exceeds 0%.
On the other hand, by setting the content of the MgO component to 10.0% or less, devitrification can be reduced while suppressing a decrease in the refractive index. Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.
As the MgO component, MgO, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

When the CaO component is contained in an amount of more than 0%, it is an optional component that can reduce the Abbe number, reduce devitrification, and increase the meltability of the glass raw material while reducing the material cost of the glass.
On the other hand, by making the content of the CaO component 10.0% or less, a decrease in refractive index, an increase in Abbe number, and an increase in partial dispersion ratio can be suppressed, and devitrification can be reduced. Moreover, this can suppress deterioration of chemical durability. Therefore, the content of the CaO component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.
As the CaO component, CaCO ₃ , CaF ₂ or the like can be used as a raw material.

The SrO component is an optional component that can increase the refractive index and increase the resistance to devitrification when it contains more than 0%.
In particular, deterioration of chemical durability can be suppressed by setting the content of the SrO component to 10.0% or less. Therefore, the content of the SrO component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, and further preferably less than 1.0%.
As the SrO component, Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

When the BaO component is contained in excess of 0%, the refractive index can be increased, the partial dispersion ratio can be lowered, the devitrification resistance can be increased, the melting property of the glass raw material can be increased, and other alkaline earth components It is an optional component that can reduce the material cost of glass compared to
In particular, by setting the content of the BaO component to 10.0% or less, a decrease in refractive index, an increase in Abbe number, and an increase in partial dispersion ratio can be suppressed, and devitrification can be reduced. Therefore, the content of the BaO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ or the like can be used as a raw material.

The ZnO component is an optional component that is inexpensive, can improve devitrification resistance, and can lower the glass transition point when it is contained in excess of 0%. Therefore, the content of the ZnO 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 ZnO component to 25.0% or less, chemical durability can be enhanced while reducing devitrification and coloring. Therefore, the content of the ZnO component is preferably 25.0% or less, more preferably 20.0% or less, more preferably less than 13.0%, and even more preferably less than 10.0%.

La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are optional components that can increase the refractive index and reduce the partial dispersion ratio by containing at least one of them in excess of 0%. It is an ingredient.
In particular, by reducing the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, and Yb ₂ O ₃ component to 10.0% or less, an increase in the Abbe number can be suppressed. Throughness can be reduced and material cost can be reduced. Accordingly, the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably The upper limit is 3.0%, and more preferably less than 1.0%.
La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Y ₂ O ₃ , YF ₃ , Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index, decrease the Abbe number and the partial dispersion ratio, and increase the devitrification resistance when the content exceeds 0%.
On the other hand, by making the content of Ta ₂ O ₅ component 10.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is easily melted at a lower temperature. Glass production costs can be reduced. Moreover, this can reduce the devitrification of the glass due to excessive inclusion of the Ta ₂ O ₅ component. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%. In particular, from the viewpoint of reducing the material cost of glass, the Ta ₂ O ₅ component may not be contained.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component that can increase the refractive index and decrease the Abbe number, increase the devitrification resistance, and increase the meltability of the glass raw material when it contains more than 0%.
On the other hand, by making the content of the WO ₃ component 10.0% or less, it is possible to make it difficult to raise the partial dispersion ratio of the glass, and to reduce the coloring of the glass and to increase the internal transmittance. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances the stability of the glass.
On the other _hand, when the content of P 2 _{O 5} component to 10.0% or _less, can be reduced devitrification due to excessive content of P 2 _{O 5} component. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index and reduce devitrification when it contains more than 0%.
On the other hand, by making the content of the GeO ₂ component 10.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the material cost of the glass can be reduced. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, still 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 Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can increase chemical durability and improve devitrification resistance when at least one of them is contained in excess of 0%.
On the other hand, devitrification due to excessive inclusion of Al ₂ O ₃ component or Ga ₂ O ₃ component is reduced by making each content of Al ₂ O ₃ component and Ga ₂ O ₃ component 10.0% or less. it can. Accordingly, the content of each 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 even more preferably 1. Less than 0%.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ 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 and lower the Abbe number and lower the glass transition point when it exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio, and it is possible to reduce the coloring of the glass and increase the internal transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index, lower the partial dispersion ratio, and lower the glass transition point when contained in excess of 0%.
On the other hand, by setting the content of the TeO ₂ component to 5.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. Moreover, glass with lower material costs can be obtained by reducing the use of expensive TeO ₂ components. Therefore, the content of the TeO ₂ component is preferably 5.0% or less, 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.

The SnO ₂ component is an optional component that can clarify (defoam) the molten glass and increase the visible light transmittance of the glass when it contains more than 0%.
On the other hand, by making the content of the SnO ₂ component 1.0% or less, it is possible to make it difficult to cause coloration of the glass due to the reduction of the molten glass and devitrification of the glass. 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 1.0% or less, more preferably less than 0.5%, and even more 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 Sb ₂ O ₃ component is a component that accelerates the defoaming of the glass when it contains more than 0% and clarifies the glass, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ component, by a content relative to the glass total weight 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially Pt And the like can be made difficult to alloy. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.8%, and still more preferably 0.6%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · ₅ H ₂ O, or the like can be used as a raw material.

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

The total amount (mass sum) of the SiO ₂ component and the Nb ₂ O ₅ component is preferably more than 50.0%. Thereby, it is possible to obtain a glass having excellent chemical durability, small anomalous dispersion, and good moldability while maintaining a certain viscosity.
Therefore, this mass sum is preferably more than 50.0%, more preferably 53.0% or more, further preferably 54.0% or more, and further preferably 58.0% or more.
On the other hand, this mass sum is preferably 90.0% or less, more preferably less than 85.0%, even more preferably less than 81.0%, and even more preferably less than 76.0%.

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) is preferably 15.0% or less. Thereby, devitrification of glass can be reduced, an increase in the Abbe number can be suppressed, and the material cost of the glass can be reduced. Therefore, the mass sum of the Ln ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, and even more preferably less than 3.5%.

The sum (mass sum) of the contents of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 30.0% or less. Thereby, devitrification of the glass due to excessive inclusion of these components can be reduced. Therefore, the mass sum of the RO component is preferably 30.0% or less, more preferably 25.0% or less, still more preferably 20.0% or less, still more preferably 15.0% or less, and even more preferably 10.0. %, More preferably less than 5.0%.
On the other hand, the mass sum of the RO component is preferably more than 0%, more preferably 1.0% or more, and still more preferably 2.0% or more, from the viewpoint of increasing the meltability of the glass raw material and reducing devitrification. May be the lower limit.

<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 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. 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, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1000 to 1400 ° C. for 3 to 5 hours, stir to homogenize, blow out bubbles, etc., then lower the temperature to 900 to 1100 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention has a high refractive index and an Abbe number in a predetermined range.
The refractive index (n _d ) of the optical glass of the present invention is preferably 1.60, more preferably 1.63, and still more preferably 1.65. The upper limit of this refractive index is preferably 1.78, more preferably 1.77, and even more preferably 1.76.
The Abbe number (ν _d ) of the optical glass of the present invention is preferably 28, more preferably 29, and still more preferably 30. On the other hand, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 47, more preferably 45, still more preferably 43, still more preferably 42, and still more preferably 41.
The optical glass of the present invention having such a refractive index and Abbe number is useful in optical design, and the optical system can be miniaturized while achieving particularly high imaging characteristics. Can expand the degree.

The optical glass of the present invention has a low partial dispersion ratio (θg, F).
More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is as follows. The partial dispersion ratio (θg, F) of the optical glass of the present invention is between the Abbe number (ν _d ). , (−0.00256 × ν _d +0.637) ≦ (θg, F) ≦ (−0.00256 × ν _d +0.684) is preferably satisfied.
Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) preferably satisfy the relationship θg, F ≧ (−0.00256 × ν _d +0.637). It is more preferable to satisfy the relationship of θg, F ≧ (−0.00256 × ν _d +0.647), and it is more preferable to satisfy the relationship of θg, F ≧ (−0.00256 × ν _d +0.657).
On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) preferably satisfy the relationship of θg, F ≦ (−0.00256 × ν _d +0.684). , Θg, F ≦ (−0.00256 × ν _d +0.681), and more preferably satisfy the relationship θg, F ≦ (−0.00256 × ν _d +0.677). .
As a result, an optical glass having a low partial dispersion ratio (θg, F) can be obtained. Therefore, an optical element formed from the optical glass can be used to reduce chromatic aberration of the optical system.

In particular, in the region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of a general glass is higher than that of the normal line, the Abbe number (ν _d ) on the horizontal axis and the vertical axis on the vertical axis. When the partial dispersion ratio (θg, F) is taken, the relationship between the general glass partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is expressed by a curve having a larger slope than the normal line. . In the relational expression of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) described above, by defining these relations using a straight line having a larger slope than the normal line, partial dispersion can be achieved as compared with general glass. This indicates that a glass having a small ratio (θg, F) can be obtained.

In the present invention, the surface method weather resistance is preferably class 1 or class 2, more preferably class 1.
Here, the surface method weather resistance is performed using the following test method.
Using a sample having a polished surface of 30 mm × 30 mm × 3 mm as a test piece, the sample was exposed to a constant temperature and humidity chamber at 60 ° C. and 95% relative humidity for 96 hours, and then the polished surface was observed with a 50 × microscope. Observe the state. Judgment criteria are class 1 when no sample is observed when observing a sample tested for 96 hours at an illuminance of 1500 lux, and class 2 when no sample is observed when observing at 100 lux. Grade 3 was observed when it was observed at 100 lux. As for grade 3, after newly exposing to a constant temperature and humidity chamber of 50 ° C. and 85% relative humidity for 6 hours, the polished surface was observed with a 50 × microscope, and burns were recognized at 1500 lux. It was. If no discoloration was observed, it was left as Grade 3.

  In the present specification, “surface method weather resistance” means, for example, superiority or inferiority of a burnt state when used as a lens preform material for a long period of time or when exposed for a certain period depending on the storage environment of optical glass. It shows that.

The optical glass of the present invention is preferably less colored.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₈₀ ) exhibiting a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 420 nm or less, more preferably 400 nm or less, and even more preferably. 380 nm or less.
In the optical glass of the present invention, a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 365 nm or less, more preferably 345 nm or less, and further preferably 330 nm or less.
Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be preferably used as a material for an optical element such as a lens.

[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 is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

The compositions of Examples (No. 1 to No. 55) and Comparative Examples of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), and spectral transmittance are 5 Tables 1 to 8 show the results of the wavelengths (λ ₅ , λ ₈₀ ) indicating% and 80%, and the liquidus temperature. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of Examples and Comparative Examples are used as ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc., as raw materials for the respective components. High-purity raw materials are selected, weighed so as to have the composition ratios of the examples and comparative examples shown in the table, and mixed uniformly, and then a stone crucible (platinum crucible, alumina depending on the melting property of the glass) It may be used in a crucible) and melted in a temperature range of 1100 to 1400 ° C. for 0.5 to 5 hours in an electric furnace according to the melting difficulty of the glass composition, then transferred to a platinum crucible and homogenized with stirring. After the foam was blown out, the temperature was lowered to 1000 to 1400 ° C., homogenized with stirring, cast into a mold, and slowly cooled to produce glass.

The refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg, F) of the glasses of Examples and Comparative Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003.
In addition, the glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

The surface method weather resistance of Examples and Comparative Examples was evaluated by the following method.
Using a sample having a polished surface of 30 mm × 30 mm × 3 mm as a test piece, the sample was exposed to a constant temperature and humidity chamber at 60 ° C. and 95% relative humidity for 96 hours, and then the polished surface was observed with a 50 × microscope. Observe the state. Judgment criteria are class 1 when no sample is observed when observing a sample tested for 96 hours at an illuminance of 1500 lux, and class 2 when no sample is observed when observing at 100 lux. Grade 3 was observed when it was observed at 100 lux. As for grade 3, after newly exposing to a constant temperature and humidity chamber of 50 ° C. and 85% relative humidity for 6 hours, the polished surface was observed with a 50 × microscope, and burns were recognized at 1500 lux. It was. If no discoloration was observed, it was left as Grade 3.

The transmittance | permeability of the glass of an Example and a comparative example was measured according to Japan Optical Glass Industry Association standard JOGIS02. 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 ₅ (wavelength when the transmittance was 5%) and λ ₈₀ (transmittance). Wavelength at 80%).

As shown in these tables, in the optical glass of the example of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) are (−0.00256 × ν _d +0.637) ≦ (θg, F ) ≦ (−0.00256 × ν _d +0.684), and more specifically, (−0.00256 × νd + 0.657) ≦ (θg, F) ≦ (−0.00256 × ν _d +0.677). Here, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the example of the present application is as shown in FIG.

Further, the optical glass of the examples of the present invention had a surface method weather resistance of class 1.
For this reason, the optical glass of the present invention was found to be excellent in surface method weather resistance, and is an optical glass that is difficult to cause so-called burns.

In addition, the optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.60 or more, more specifically 1.65 or more, and this refractive index (n _d ) is 1.78. Hereinafter, it was 1.76 or less in more detail, and was within a desired range.
Further, the optical glasses of the examples of the present invention all had an Abbe number (ν _d ) of 28 or more, more specifically 30 or more. Further, the optical glass of the example of the present invention had an Abbe number (ν _d ) of 47 or less, more specifically 46 or less, and was within a desired range.

In addition, the optical glasses of the examples of the present invention each had a λ ₈₀ (wavelength at 80% transmittance) of 420 nm or less, more specifically 400 nm or less.
In addition, in the optical glass of the example of the present invention, each of λ ₅ (wavelength at 5% transmittance) was 365 nm or less, more specifically 345 nm or less, and more specifically 340 nm or less.
Therefore, it became clear that the optical glass of the Example of this invention has the high transmittance | permeability with respect to visible light, and is hard to be colored.

On the other hand, the optical glass described in the comparative example satisfies the desired optical constants (n _d , ν _d ), but has a large partial dispersion ratio, so that anomalous dispersibility is small and transmittance is poor, and chemical durability is high. The refractive index (n _d ) and the Abbe number (ν _d ), which are the objectives of the present invention, are within the desired ranges, but the partial dispersion ratio (θg, F) is small, and the surface method weather resistance is low. A good optical glass could not be obtained.

  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 (8)

In mass% of oxide equivalent composition,
20.0 to 60.0% of SiO ₂ component,
10.0-50.0% of Nb ₂ O ₅ component,
K ₂ O component exceeds 0.1 to 15.0%
Contains,
Between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ), (−0.00256 × ν _d +0.637) ≦ (θg, F) ≦ (−0.00256 × ν _d +0.684) )
Optical glass whose surface method weather resistance is class 1 or 2. In mass% of oxide equivalent composition,
TiO ₂ component 0 to 10.0%
B ₂ O ₃ component 0 to 20.0%
Li ₂ O component 0 to 15.0%
Na ₂ O component 0 to 15.0%
And
_2. The optical glass according to claim 1, wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) has a mass sum of 5.0% to 30.0%. . In mass% of oxide equivalent composition,
ZrO ₂ component 0 to 20.0%
MgO component 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
ZnO component 0 to 25.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
WO ₃ components 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0-5.0%
SnO ₂ component 0-5.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to claim 1 or 2. The optical glass according to any one of claims 1 to 3, wherein the sum of the contents of the SiO ₂ component and the Nb ₂ O ₅ component exceeds 50.0%. The mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba) is 30.0% or less,
5. The mass sum of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of Y, La, Gd, and Yb) is 15.0% or less. 5. Optical glass. The optical glass according to any one of claims 1 to 4, which has a refractive index (n _d ) of 1.60 or more and 1.78 or less and an Abbe number (ν _d ) of 28 or more and 47 or less.   A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 5.   An optical element made of the optical glass according to claim 1.

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