JP6756482B2 - Optical glass, preforms and optics - Google Patents

Description

The present invention relates to optical glass, preforms and optical elements.

In recent years, the digitization and high definition of devices that use optical systems have been rapidly advancing, and various optical devices such as photography devices such as digital cameras and video cameras, and image reproduction (projection) devices such as projectors and projection televisions. In this field, there is an increasing demand for reducing the number of optical elements such as lenses and prisms used in an optical system, and reducing the weight and size of the entire optical system.

Among the optical glasses for which optical elements are manufactured, it has a high refractive index ( _nd ) of 1.65 or more and 1.80 or less, which enables weight reduction and miniaturization of the entire optical system, and is 40 or more and 60. The demand for high refractive index low dispersion glass having the following high Abbe number (ν _d ) is very high. As such a high refractive index low dispersion glass, glass compositions such as those represented by Patent Documents 1 to 4 are known.

Japanese Unexamined Patent Publication No. 2005-272183 International Publication No. 2007/097345 Japanese Unexamined Patent Publication No. 2013-056828 International Publication No. 09/072586

In order to reduce the material cost of the optical glass, it is desired that the raw material cost of the optical glass is as low as possible. However, it cannot be said that the glasses described in Patent Documents 1 to 4 sufficiently meet such a demand.

Further, the glass described in Patent Documents 1 to 4 has a problem that the specific gravity of the glass is large and the mass of the optical element is large. That is, when these glasses are used in an optical device such as a camera or a projector, there is a problem that the mass of the entire optical device tends to increase.

On the other hand, even when the material cost of the optical glass is reduced and the glass transition point is lowered, the optical glass is required to have high stability and hardly devitrify.

The present invention has been made in view of the above problems, and an object of the present invention is that the refractive index ( _nd ) and the Abbe number (ν _d ) are within desired ranges and that the stability is as high as possible. The purpose is to obtain expensive optical glass at a lower cost.

Further, the present invention uses an optical glass in which the refractive index ( _nd ) and the Abbe number (ν _d ) are within a desired range, the stability is high, and the weight of the optical device can be reduced. It is also an object of the present invention to provide preforms and optical elements.

As a result of intensive test and research to solve the above problems, the present inventors have found that the content of the expensive Gd ₂ O ₃ component in the glass containing the B ₂ O ₃ component and the Ln ₂ O ₃ component is high. We have found that a glass having a desired high refractive index and low dispersion and high stability can be obtained even when the amount is small, and have completed the present invention.
Specifically, the present invention provides the following.

(1) B ₂ O ₃ component is 30.0% or more and 80.0% or less, and Ln ₂ O ₃ component is 10.0% or more and 40.0% or less in mol% based on oxide (in the formula, Ln is (One or more selected from the group consisting of La, Gd, Y, Yb), the content of Gd ₂ O ₃ component is less than 5.0%, and the refractive index is 1.65 or more and 1.80 or less ( An optical glass having an nd) and having an Abbe number (νd) of 40 or more and 60 or less.

(2) In mole% based on oxide
La ₂ O ₃ component 0-30.0%,
Y ₂ O ₃ component 0 to 15.0%,
SiO ₂ component 0 to 20.0%,
Li ₂ O component 0 to 15.0%,
The optical glass according to (1).

(3) In mole% based on oxide
Yb ₂ O ₃ component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 10.0%,
MgO component 0-10.0%,
CaO component 0 to 15.0%,
SrO component 0 to 15.0%,
BaO component 0 to 15.0%,
ZnO component 0 to 25.0%,
TiO ₂ component 0 to 10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
Nb ₂ O ₅ component 0 to 10.0%,
ZrO ₂ component 0 to 15.0%,
P ₂ O ₅ component 0 to 15.0%,
GeO ₂ component 0 to 15.0%,
WO ₃ component 0-10.0%,
Al ₂ O ₃ component 0 to 15.0%,
Ga ₂ O ₃ component 0 to 15.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ component 0 to 15.0%,
SnO ₂ component 0-5.0% and Sb ₂ O ₃ component 0-1.0%
The optical glass according to (1) or (2).

(4) The optical glass according to any one of (1) to (3), wherein the molar sum (B ₂ O ₃ + SiO ₂ ) based on the oxide is 30.0% or more and 80.0% or less.

(5) On an oxide basis,
The molar sum of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is 15.0% or less.
The description of any of (1) to (4) in which the molar sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 25.0% or less. Optical glass.

(6) The optical glass according to any one of (1) to (5), wherein the molar sum (SiO ₂ + Li ₂ O) based on the oxide is 0.5% or more and 25.0% or less.

(7) The optical glass according to any one of (1) to (6), wherein the molar sum (ZnO + CaO) based on the oxide is 1.0% or more and 25.0% or less.

(8) The optical glass according to any one of (1) to (7), wherein the molar sum (SrO + BaO) based on the oxide is 15.0% or less.

(9) The optical glass according to any one of (1) to (8), wherein the molar ratio (TiO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ + ZrO ₂ ) / Ln ₂ O _{3 based on the} oxide is 0.50 or less. In the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb).

(10) The optical glass according to any one of (1) to (9), which has a specific gravity of 4.50 or less.

(11) An optical element made of the optical glass according to any one of (1) to (10).

(12) A preform for polishing and / or precision press forming made of the optical glass according to any one of (1) to (10).

(13) An optical element obtained by precision pressing the preform according to (12).

According to the present invention, it is possible to obtain an optical glass having a refractive index ( _nd ) and an Abbe number (ν _d ) within a desired range and having high stability at a lower cost.
Further, according to the present invention, it is possible to obtain an optical glass in which the refractive index ( _nd ) and the Abbe number (ν _d ) are within desired ranges, the stability is high, the specific gravity is small, and the weight of the optical element is reduced. You can also do it.

It is a figure which shows the relationship between the refractive index (nd) and the Abbe number (ν _d ) about the glass of the Example of this application.

The optical glass of the present invention, in mole percent on the oxide _basis, B 2 _{O 3} component 80.0% 30.0% or more of the following, _Ln 2 _{O 3} ingredient 10.0% or more 40.0% or less (formula Among them, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb), the content of the Gd ₂ O ₃ component is less than 5.0%, and 1.65 or more and 1.80 or less. It has a refractive index (nd) of 40 or more and an Abbe number (νd) of 40 or more and 60 or less. According to the present invention, in a glass containing a B ₂ O ₃ component and a Ln ₂ O ₃ component, a desired high refractive index and low dispersion can be obtained even when the content of the expensive Gd ₂ O ₃ component is small. A glass having high stability can be obtained. Therefore, an optical glass having a refractive index ( _nd ) and an Abbe number (ν _d ) within a desired range and high stability can be obtained at a lower cost.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and is carried out with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although the description may be omitted as appropriate for the parts where the description is duplicated, the gist of the 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, the content of each component shall be indicated in mol% based on oxides unless otherwise specified. Here, the composition of the "oxide standard" is the total of the produced oxides, assuming that all the oxides, composite salts, fluorides, etc. used as glass raw materials are decomposed at the time of melting and changed into oxides. It is a composition in which each component contained in a glass is described, with the number of moles being 100 mol%.

<About essential ingredients and optional ingredients>
The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxides.
In particular, by containing 30.0% or more of the B ₂ O ₃ component, the devitrification resistance of the glass can be enhanced, the Abbe number can be increased, and the specific gravity can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 30.0%, more preferably 40.0%, still more preferably 50.0%, still more preferably 53.0%, still more preferably 56.0%. Is the lower limit.
On the other hand, by setting the content of the B ₂ O ₃ component to 80.0% or less, the decrease in the refractive index can be suppressed and the deterioration of the chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 80.0%, more preferably 75.0%, still more preferably 72.0%, still more preferably 67.0%, still more preferably 63.0%. Is the upper limit.
B ₂ O ₃ component can be used _H 3 _BO 3 as a starting _{material, Na 2 B 4 O 7,} Na 2 B 4 O 7 · 10H 2 O, the BPO ₄ and the like.

The sum (molar sum) of the contents of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 10.0% or more and 40.0% or less. Is.
In particular, when the molar sum is 10.0% or more, the refractive index and Abbe number of the glass can be increased, so that a glass having a high refractive index and a low dispersion can be easily obtained. Therefore, the molar sum of the contents of the Ln ₂ O ₃ component is preferably 10.0%, more preferably 15.0%, still more preferably 18.0% as the lower limit.
On the other hand, when the molar sum is 40.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. In addition, this can reduce the material cost of glass. Therefore, the molar sum of the contents of the Ln ₂ O ₃ component is preferably 40.0% or less, more preferably less than 30.0%, still more preferably less than 25.0%, still more preferably less than 23.0%. To do.

The Gd ₂ O ₃ component is an optional component capable of increasing the refractive index and Abbe number and increasing the devitrification resistance when it is contained in excess of 0%.
On the other hand, by reducing the content of the Gd ₂ O ₃ component to less than 5.0%, the material cost of the glass can be suppressed. Further, this can improve the devitrification resistance and suppress the increase in specific gravity. Therefore, the content of the Gd ₂ O ₃ component is preferably less than 5.0%, more preferably less than 3.0%, still more preferably 2.1% or less, still more preferably less than 1.0%, still more preferably. It shall be 0.7% or less.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF _3, or the like can be used as a raw material.

The La ₂ O ₃ component is an optional component that can increase the refractive index of the glass and reduce the dispersion (increasing the Abbe number). Further, by containing the La ₂ O ₃ component, the content of other rare earth elements that increase the specific gravity is reduced, so that glass having a small specific gravity can be obtained more easily. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably 1.0% or more, still more preferably 3.0% or more, still more preferably 7.0% or more, still more preferably 10. It may be more than 0%, more preferably more than 13.0%.
On the other hand, by reducing the content of the La ₂ O ₃ component to 30.0% or less, the stability of the glass can be improved, devitrification can be reduced, and an increase in the Abbe number can be suppressed. Therefore, the content of the La ₂ O ₃ component is preferably 30.0% or less, more preferably less than 25.0%, still more preferably less than 20.0%, still more preferably less than 17.0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ , XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component that can increase the refractive index and Abbe number, reduce the specific gravity, and enhance the devitrification resistance when the content exceeds 0%. _Thus, Y 2 _{O 3} content component is preferably 0 percent, more preferably 1.0 percent, more preferably 2.0 percent, more preferably 3.0 percent, more preferably 5. It may be more than 0%.
On the other _hand, by the content of Y 2 _{O 3} component to 15.0% can be reduced devitrification due to excessive containing. _Accordingly, the content of Y 2 _{O 3} component is preferably 15.0% or less, more preferably less than 12.0 percent, more preferably less than 10.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF _3, or the like can be used as a raw material.

The SiO ₂ component is an optional component capable of increasing the viscosity of the molten glass, reducing the coloring of the glass, and increasing the devitrification resistance when the content exceeds 0%. Therefore, the content of the SiO ₂ component may be preferably more than 0%, more preferably more than 1.0%, still more preferably more than 4.0%, still more preferably more than 7.0%.
On the other hand, by setting the content of the SiO ₂ component to 20.0% or less, the decrease in the refractive index can be suppressed, the increase in the glass transition point can be suppressed, and the specific gravity can be reduced. Therefore, the content of the SiO ₂ component is preferably 20.0%, more preferably 18.0%, further preferably 15.0%, still more preferably 11.0%.
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 Li ₂ O component is an optional component that can improve the meltability of the glass and lower the glass transition point when the content exceeds 0%. Therefore, the content of the Li ₂ O component may be preferably more than 0%, more preferably more than 0.3%, still more preferably more than 0.6%, still more preferably more than 1.0%.
On the other hand, by reducing the content of the Li ₂ O component to 15.0% or less, a decrease in the refractive index and devitrification can be reduced, and the chemical durability can be improved. Further, since the viscosity of the molten glass is increased by this, the occurrence of veins on the glass can be reduced. Therefore, the content of the Li ₂ O component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 6.0%, still more preferably less than 4.0%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component that can increase the refractive index and Abbe number and enhance the devitrification resistance when it contains more than 0%.
On the other hand, by reducing the content of the Yb ₂ O ₃ component to 10.0% or less, devitrification due to excessive content can be reduced, an increase in specific gravity can be suppressed, and the material cost of glass can be suppressed. Therefore, the content of the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, still more preferably less than 1.0%.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are optional components that can improve the meltability of the glass raw material, increase the devitrification resistance, and lower the glass transition point when at least one of them is contained in excess of 0%. is there.
On the other hand, by setting the content of each of the Na ₂ O component and the K ₂ O component to 10.0% or less, it is possible to make it difficult to reduce the refractive index, and it is possible to reduce devitrification due to excessive content. Therefore, the respective contents of the Na ₂ O component and the K ₂ O component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1.0. It shall be less than%.
As the Na ₂ O component and the K ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _6, etc. can be used as raw materials. it can.

The MgO component and the CaO component are optional components that can reduce the specific gravity and enhance the meltability of the glass raw material and the devitrification resistance of the glass when at least one of them is contained in excess of 0%.
On the other hand, by reducing the content of the MgO component to 10.0% or less or the content of the CaO component to 10.0% or less, the refractive index is lowered or devitrified due to the excessive content of these components. Can be suppressed.
Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
The content of the CaO component is preferably 15.0% or less, more preferably less than 12.0%, further preferably less than 10.0%, still more preferably less than 7.0%, still more preferably 4.0. It shall be less than%.
As the MgO component and the CaO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF _{2 and the} like can be used as raw materials.

When the SrO component and the BaO component are contained in excess of 0%, the material cost can be suppressed while increasing the refractive index of the glass, and the meltability and devitrification resistance of the glass raw material can be enhanced.
On the other hand, by setting the content of each of the SrO component and the BaO component to 15.0% or less, devitrification due to excessive content and an increase in specific gravity can be suppressed. Therefore, the respective contents of the SrO component and the BaO component are preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, still more preferably less than 3.0%. ..
As the SrO component and the BaO component, Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF _{2, and the} like can be used as raw materials.

The ZnO component is an optional component that can lower the glass transition point, reduce the specific gravity, and enhance the chemical durability when the content exceeds 0%. Therefore, the content of the ZnO component may be preferably more than 0%, more preferably more than 1.0%, still more preferably more than 4.0%, still more preferably more than 7.0%.
On the other hand, by reducing the content of the ZnO component to 25.0% or less, a decrease in the refractive index and devitrification can be reduced. Further, since the viscosity of the molten glass is increased by this, the occurrence of veins on the glass can be reduced. Therefore, the content of the ZnO component is preferably 25.0%, more preferably 22.0%, further preferably 20.0%, still more preferably 16.0%.
As the ZnO component, ZnO, ZnF _2, or the like can be used as a raw material.

The TiO ₂ component is an optional component that can increase the refractive index, reduce the specific gravity, and enhance the stability when the content exceeds 0%.
On the other hand, by setting the content of the TiO ₂ component to 10.0%, it is possible to suppress a decrease in the Abbe number, increase the visible light transmittance, and suppress devitrification due to excessive content. Therefore, the content of the TiO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 0.8%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index, the devitrification resistance, and the viscosity of the molten glass when the content exceeds 0%.
On the other hand, by reducing the content of the Ta ₂ O ₅ component to 10.0% or less, the amount of the Ta ₂ O ₅ component used, which is a rare mineral resource, is reduced, so that the material cost of glass can be reduced. In addition, this makes it possible to reduce the specific gravity. 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%, still more preferably less than 1.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Nb ₂ O ₅ component is an optional component that can increase the refractive index of the glass and enhance the devitrification resistance when it is contained in excess of 0%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 10.0% or less, it is possible to suppress a decrease in the Abbe number, a decrease in devitrification resistance, and a decrease in visible light transmittance due to excessive content. .. Further, as a result, the specific gravity of the glass can be reduced and the material cost can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

ZrO ₂ component, when 0% ultra-containing, can contribute to a high refractive index of the glass and lowering dispersion (high Abbe number of), and is an optional component that enhances devitrification resistance. Therefore, the content of the ZrO ₂ component is preferably 0 percent, more preferably 0.1% or more, more preferably it may be 0.2% or more.
On the other hand, by making the ZrO ₂ component below 15.0%, it suppressed the devitrification due to excessive containing. Therefore, the content of the ZrO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF _4, or the like can be used as a raw material.

The P ₂ O ₅ component is an optional component whose devitrification resistance can be enhanced when the content exceeds 0%.
On the other hand, by reducing the content of the P ₂ O ₅ component to 15.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, particularly the water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%.
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, and the} like can be used as raw materials.

The GeO ₂ component is an optional component that can increase the refractive index of glass and increase the devitrification resistance when it is contained in excess of 0%.
However, since the raw material price of GeO ₂ is high, if the amount is large, the material cost is high, and the effect of cost reduction by reducing the Gd ₂ O ₃ component and the like is diminished. Therefore, the content of the GeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 1.0%.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The WO ₃ component is an optional component capable of increasing the refractive index, lowering the glass transition point, and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, by the content of WO ₃ ingredient 10.0% or less, it suppressed the decrease in the Abbe number of the glass, can hardly reduce the transmittance of visible light, and suppress the material cost. 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%, still more preferably less than 1.0%.
As the WO ₃ component, WO ₃ 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 enhance chemical durability and devitrification resistance when the content exceeds 0%.
On the other hand, by setting the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 15.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably 3. It shall be less than 0.0%.
As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) _{3 and the} like can be used as raw materials.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it contains more than 0%.
On the other hand, by reducing the content of the Bi ₂ O ₃ component to 10.0% or less, it is possible to suppress a decrease in the Abbe number and the devitrification resistance of the glass, and reduce the coloring of the glass to make visible light. The transmittance can be increased. 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%, still more preferably less than 1.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when the content exceeds 0%.
On the other hand, by reducing the content of the TeO ₂ component to 15.0% or less, the coloring of the glass can be reduced and the visible light transmittance can be increased. Further, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which a portion in contact with molten glass is made of platinum. Therefore, the content of the TeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 1.0%.
As the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an optional component that can increase the visible light transmittance of the glass while reducing the oxidation of the molten glass and clarifying it when the content exceeds 0%.
On the other hand, by reducing the content of the SnO ₂ component to 5.0% or less, it is possible to reduce the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass. Further, since the alloying of the SnO ₂ component and the melting equipment (particularly 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 5.0%, more preferably 3.0%, still more preferably 1.0%, and further preferably less than 0.1%.
As 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 an optional component capable of defoaming the molten glass when it contains more than 0%.
On the other hand, if the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region becomes poor. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.5%, and even more preferably 0.3%.
Sb ₂ O ₃ component can be used _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O and the like as raw materials.

The component that clarifies and defoams the glass is not limited to the above Sb ₂ O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the field of glass production can be used.

The sum (molar sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 30.0% or more and 80.0% or less.
In particular, by setting this sum to 30.0% or more, it is possible to suppress a decrease in devitrification resistance due to a deficiency of the B ₂ O ₃ component and the SiO ₂ component. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0%, more preferably 35.0%, still more preferably 43.0%, still more preferably 50.0%, still more preferably 56. The lower limit is 0%, more preferably 60.0%, still more preferably 63.0%.
On the other hand, by setting this sum to 80.0% or less, a decrease in the refractive index due to excessive content can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 80.0%, more preferably 78.0%, still more preferably 75.0%, still more preferably 73.0%, still more preferably 70. The upper limit is 0%.

The sum (molar sum) of the contents of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 15.0% or less.
As a result, a decrease in the refractive index of the glass can be suppressed and devitrification can be reduced. Therefore, the molar sum of the contents of the Rn ₂ O component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 7.0%, still more preferably less than 4.0%. ..
On the other hand, by setting this sum to more than 0%, the meltability of the glass raw material and the stability of the glass can be improved. Therefore, the total content of the Rn ₂ O component may be preferably more than 0%, more preferably 0.6% or more, still more preferably more than 1.0%.

The sum (molar sum) of the contents of the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is preferably 25.0% or less. As a result, devitrification due to excessive inclusion of the RO component can be reduced, and a decrease in the refractive index can be suppressed. Therefore, the total content of the RO components is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 16.0%, still more preferably less than 10.0%.
On the other hand, by setting this sum to more than 0%, the meltability of the glass raw material and the stability of the glass can be improved. Therefore, the total content of the RO component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 2.0%, still more preferably more than 4.0%, still more preferably 7.0%. It may be super.

Rn ₂ O component (Rn is selected from the group consisting of Li, Na, K) with respect to the sum of the contents of the Ln ₂ O ₃ component (Ln is one or more selected from the group consisting of La, Gd, Y, Yb). The ratio (molar ratio) of the sum of the contents of (one or more kinds) is preferably 0.50 or less.
This makes it easy to obtain stable glass with a high refractive index. Therefore, the molar ratio Rn ₂ O / Ln ₂ O ₃ is preferably 0.50, more preferably 0.40, still more preferably 0.25, still more preferably 0.20.
On the other hand, the lower limit of this ratio may be more than 0 and may be 0.03 or more from the viewpoint of further enhancing the devitrification resistance and meltability of the glass.

The sum (molar sum) of the contents of the SiO ₂ component and the Li ₂ O component is preferably 0.5% or more and 25.0% or less. By keeping this total amount within the above range, a glass having a desired balance between the refractive index and the Abbe number can be obtained.
Therefore, the molar sum (SiO ₂ + Li ₂ O) is preferably 0.5% or more, more preferably 1.0% or more, still more preferably 3.0% or more, still more preferably 5.0% or more, still more preferably. Is more than 7.0%, more preferably more than 8.0%.
On the other hand, the molar sum (SiO ₂ + Li ₂ O) is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 16.0%, still more preferably less than 13.0%. ..

The sum (molar sum) of the contents of the ZnO component and the CaO component is preferably 1.0% or more and 25.0% or less.
In particular, by setting this sum to 1.0% or more, the refractive index can be easily increased, the glass transition point can be lowered, and the specific gravity can be reduced. Therefore, the molar sum (ZnO + CaO) is preferably 1.0% or more, more preferably more than 2.0%, still more preferably more than 4.0%, still more preferably 5.8% or more, still more preferably 7.0. % Or more.
On the other hand, by setting this sum to 25.0% or less, devitrification and a decrease in the refractive index due to excessive content can be suppressed. Therefore, the molar sum (CaO + ZnO) is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 18.0%, still more preferably less than 16.0%.

The sum (molar sum) of the contents of the SrO component and the BaO component is preferably 15.0% or less. As a result, an increase in specific gravity can be suppressed. Therefore, the molar sum (SrO + BaO) is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 7.0%, still more preferably less than 5.0%, still more preferably 1.0. It shall be less than%.

The sum (molar sum) of the contents of the TiO ₂ component, the Ta ₂ O ₅ component, the Nb ₂ O ₅ component and the ZrO ₂ component is preferably 15.0% or less. As a result, it is possible to suppress a decrease in the Abbe number of the glass and achieve low dispersion. Therefore, the molar sum (TiO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ + ZrO ₂ ) is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 4.5%, still more preferably 3. It is less than 0.0%, more preferably less than 1.0%, still more preferably less than 0.6%.

One selected from the group consisting of Ln ₂ O ₃ component (Ln is La, Gd, Y, Yb) with respect to the sum of the contents of TiO ₂ component, Ta ₂ O ₅ component, Nb ₂ O ₅ component and ZrO ₂ component. The sum ratio (molar ratio) of the contents of (above) is preferably 0.50 or more.
As a result, it is possible to suppress a decrease in the Abbe number of the glass and achieve low dispersion. Therefore, the molar ratio (TiO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ + ZrO ₂ ) / Ln ₂ O ₃ is preferably 0.50, more preferably 0.30, still more preferably 0.23, still more preferably 0. The upper limit is 10, more preferably 0.05, and even more preferably 0.03.

<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 preferable to be contained will be described.

Other components can be added as needed within a range that does not impair 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 used alone. Alternatively, even if the glass is compounded and contained in a small amount, the glass is colored and has a property of causing absorption at a specific wavelength in the visible region. ..

Further, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, it is desirable that they are not substantially contained, that is, they are not contained at all except for unavoidable contamination.

Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from using as a harmful chemical substance in recent years, and is used not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Up to this point, environmental measures are required. Therefore, when the environmental impact is emphasized, 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 to be roughly melted, and then a platinum crucible or a platinum alloy. Place in a crucible or iridium crucible and melt in a temperature range of 1100 to 1400 ° C for 3 to 5 hours, homogenize with stirring to break bubbles, etc., then lower the temperature to 1000 to 1300 ° C and perform finish stirring to pulse. It is produced by removing the crucible, casting it in a mold, and slowly cooling it.

<Physical properties>
The optical glass of the present invention has a high refractive index and low dispersion (high Abbe number).
In particular, the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.65, more preferably 1.67, still more preferably 1.69, still more preferably 1.71 as the lower limit. The upper limit of the refractive index may be preferably 1.80 or less, more preferably 1.77 or less, and further preferably less than 1.75. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 45, still more preferably 50, still more preferably 52 as the lower limit, preferably 60, more preferably 58, still more preferably. The upper limit is 55.
Since the optical glass of the present invention has such a refractive index and Abbe number, it is useful in optical design, and it is possible to reduce the size of the optical system while achieving particularly high imaging characteristics, and the optical design can be achieved. You can expand the degree of freedom of.

Here, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (−0.01νd + 2.17) ≦ nd ≦ (−0.01νd + 2.37). In the glass having the composition specified in the present invention, a more stable glass can be obtained by satisfying this relationship between the refractive index (nd) and the Abbe number (νd).
Therefore, in the optical glass of the present invention, the refractive index (nd) and the Abbe number (νd) preferably satisfy the relationship of nd ≧ (−0.01 νd + 2.17), and nd ≧ (−0.01 νd + 2.21). It is more preferable to satisfy the relationship of nd ≧ (−0.01 νd + 2.25).
On the other hand, in the optical glass of the present invention, the refractive index (nd) and the Abbe number (νd) preferably satisfy the relationship of nd ≦ (−0.01 νd + 2.37), and nd ≦ (−0.01 νd + 2.33). ) Is more preferable, and nd ≦ (−0.01νd + 2.29) is more preferable.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is preferably 4.50 or less. As a result, the mass of the optical element and the optical device using the optical element is reduced, which can contribute to the weight reduction of the optical device. Therefore, the specific gravity of the optical glass of the present invention is preferably 4.50, more preferably 4.30, and even more preferably 4.10. The specific gravity of the optical glass of the present invention is often 3.00 or more, more specifically 3.50 or more, and more specifically 3.80 or more.
The specific gravity of the optical glass of the present invention is measured based on the Japan Optical Glass Industry Association standard JOBIS05-1975 “Method for measuring the specific gravity of optical glass”.

The optical glass of the present invention is preferably a stable glass having high devitrification resistance (sometimes referred to simply as "devitrification resistance" in the specification) during glass production. As a result, a decrease in transmittance due to crystallization of the glass during glass production is suppressed, so that this optical glass can be preferably used for an optical element such as a lens that transmits visible light. As a measure of high devitrification resistance during glass production, for example, a low liquidus temperature can be mentioned.

[Glass molded body and optical element]
From the produced optical glass, a glass molded body can be produced by using, for example, a means for polishing, or a means for mold press molding such as reheat press molding or precision press molding. That is, a glass molded body is produced by performing machining such as grinding and polishing on optical glass, or reheat press molding is performed on a preform produced from optical glass and then polishing is performed to perform glass molding. A body can be produced, a preform produced by polishing, or a preform formed by a known levitation molding or the like can be subjected to precision press molding to produce a glass molded body. The means for producing the glass molded product is not limited to these means.

As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferable to use it for optical elements such as lenses and prisms. This makes it possible to form a glass molded body with a large diameter, so that while increasing the size of the optical element, high-definition and highly accurate imaging characteristics and projection when used in optical equipment such as cameras and projectors. The characteristics can be realized.

Tables 1 to 6 show the compositions of Examples (No. 1 to No. 41) and Comparative Example (No. A) of the present invention, as well as the refractive index ( _nd ), Abbe number (ν _d ), and specific gravity. ..
The following examples are for illustrative purposes only, and are not limited to these examples.

The glasses of Examples and Comparative Examples are both used as ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to each component as raw materials. High-purity raw materials are selected, weighed so as to have the composition ratio of each example and comparative example shown in the table, mixed uniformly, and then put into a platinum crucible, depending on the difficulty of melting the glass composition. Melt in an electric furnace in a temperature range of 1100 to 1400 ° C. for 3 to 5 hours, agitate and homogenize to break bubbles, etc., then lower the temperature to 1000 to 1300 ° C. to agitate and homogenize, and then cast into a mold. The glass was prepared by slow cooling.

The refractive index of the glass of the Examples and Comparative Examples _{(n d)} and Abbe number ([nu _d) was measured according to Japan Optical Glass Industry Society Standard JOGIS01-2003. Then, from the obtained values of the refractive index ( _nd ) and the Abbe number (ν _d ), the intercept b in the relational expression n _d = −a × ν _d + b when the slope a is 0.01 was obtained.
The glass used for this measurement was treated in a slow cooling furnace at a slow cooling rate of −25 ° C./hr.

The specific gravity of the glass of Examples and Comparative Examples was measured based on the Japan Optical Glass Industry Association standard JOBIS05-1975 “Method for measuring the specific gravity of optical glass”.

As shown in these tables, the optical glass of the embodiment of the present invention has a low content of an expensive component, particularly a Gd ₂ O ₃ component, and can be obtained at a lower cost. On the other hand, the glass of the comparative example had a high content of the Gd ₂ O ₃ component and had a high material cost.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.65 or more, with more particularly 1.70 or more, the refractive index _{(n d)} is 1.80 or less More specifically, it was 1.75 or less, which was within the desired range.

Further, all of the optical glasses of the examples of the present invention have an Abbe number (ν _d ) of 40 or more, more specifically 50 or more, and this Abbe number (ν _d ) is 60 or less, more specifically 55. It was below and was within the desired range.

Further, in the optical glass of the embodiment of the present invention, the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (−0.01νd + 2.17) ≦ nd ≦ (−0.01νd + 2.37). More specifically, the relationship of (−0.01 νd + 2.25) ≦ nd ≦ (−0.01 νd + 2.29) was satisfied. Then, the relationship between the refractive index (nd) and the Abbe number (νd) for the glass of the embodiment of the present application is shown in FIG.
All of these optical glasses were stable glasses that did not devitrify.
Therefore, it has been clarified that the optical glass of the embodiment of the present invention has a refractive index ( _nd ) and an Abbe number (ν _d ) within a desired range, and a highly stable optical glass can be obtained. It was.

Further, all of the optical glasses of the examples of the present invention had a specific gravity of 4.50 or less, more specifically 4.10 or less, which were within a desired range.
On the other hand, the glass of the comparative example had a specific gravity of more than 4.50.
Therefore, it has been clarified that the optical glass of the example of the present invention has a smaller specific gravity than the glass of the comparative example and contributes to the weight reduction of the optical element.

Therefore, the optical glass of the embodiment of the present invention has a refractive index ( _nd ) and an Abbe number (ν _d ) within desired ranges, has a small specific gravity, contributes to weight reduction of the optical element, and is stable. It became clear that the sex was high.

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

Claims (6)

In mole% of oxide standard,
B ₂ O ₃ component 56.0 % or more and 80.0% or less (excluding 56.0%) ,
La ₂ O ₃ component 0-30.0%,
Y ₂ O ₃ component 0 to 15.0%,
SiO ₂ component 0 to 11.0%,
Li ₂ O component 0 to 15.0%,
The content of Gd ₂ O ₃ component is less than 5.0%,
Ln ₂ O ₃ component is contained in 10.0% or more and 40.0% or less (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, Yb).
Oxide-based molar ratio (TiO ₂ + Ta ₂ O ₅ + Nb ₂ O ₅ + ZrO ₂ ) / Ln ₂ O ₃ is 0.10 or less.
The molar sum (ZnO + CaO) based on the oxide is 1.0% or more and less than 16.0%.
The specific gravity is 4.50 or less,
It has a refractive index (nd) of 1.67 or more and 1.80 or less, and has an Abbe number (νd) of 52 or more and 60 or less.
Refractive index (nd) of and the Abbe number ([nu] d) is, (- 0.01νd + 2.17) ≦ nd ≦ (-0.01νd + 2.37) optical glass satisfying the relationship. The molar sum of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) based on the oxide is 15.0% or less.
The optical glass according to claim 1 , wherein the molar sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) is 25.0% or less. The optical glass according to claim 1 or 2 , wherein the molar sum (SiO ₂ + Li ₂ O) based on the oxide is 0.5% or more and 25.0% or less. The optical glass according to any one of claims 1 to 3 , wherein the molar sum (SrO + BaO) based on the oxide is 15.0% or less. An optical element made of the optical glass according to any one of claims 1 to 4 . A preform for polishing and / or precision press forming made of the optical glass according to any one of claims 1 to 4 .

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