JP2016088835A - Optical glass, preform and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass suitable for an optical element having refraction index (n) and Abbe number (ν) in a desired range, low in glass transition point and suitable for press molding, and having high stability and low cost.SOLUTION: An optical glass contains, by mol%, a BOcomponent of 10.0 to 50.0%, a LnOcomponent of 10.0 to 35.0%, where Ln is one or more kind selected from La, Gd, Y, Yb, and a ZnO component of 1.0 to 35.0% and has refractive index (nd) of 1.80 to 2.20, Abbe number (νd) of 25 to 38 and glass transition point (Tg) of 650°C or less.SELECTED DRAWING: Figure 1

Description

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

  In recent years, digitization and high definition of devices using optical systems have been rapidly progressing, and various optical devices such as photographing 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 to reduce the number of optical elements such as lenses and prisms used in the optical system, and to reduce the weight and size of the entire optical system.

Among optical glasses for producing optical elements, in particular, it has a high refractive index (n _d ) of 1.80 or more and 2.20 or less, which can reduce the weight and size of the entire optical system, and 25 or more and 38. The demand for high refractive index and high dispersion glass having the following low Abbe number (ν _d ) is greatly increasing. As such a high refractive index and low dispersion glass, glass compositions represented by Patent Documents 1 to 3 are known.

JP2013-209286A JP 2009-179510 A JP 2010-030879 A

  However, although the glasses disclosed in Patent Documents 1 to 3 have high refractive index and high dispersion, they have a high glass transition point and cannot be said to be suitable for press molding. Moreover, it is hard to say that the glass disclosed in Patent Documents 1 to 3 has high stability, and devitrification may occur.

The present invention has been made in view of the above-mentioned problems. The object of the present invention is to have a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, and a low glass transition point. An object of the present invention is to provide an optical glass suitable for press molding and having high devitrification resistance, and a preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies. As a result, when a ZnO component is used in combination with the B ₂ O ₃ component and the Ln ₂ O ₃ component, the desired high refractive index and The inventors have found that a glass having a low glass transition point and high stability can be obtained while obtaining high dispersion, and the present invention has been completed.
Specifically, the present invention provides the following.

(1) In mol%, the B ₂ O ₃ component is 10.0% or more and 50.0% or less, and the Ln ₂ O ₃ component is 10.0% or more and 35.0% or less (wherein Ln is La, Gd, 1 or more selected from the group consisting of Y and Yb), and a ZnO component of 1.0 to 35.0%, a refractive index (nd) of 1.80 or more and 2.20 or less, and 25 or more An optical glass having an Abbe number (νd) of 38 or less and a glass transition point (Tg) of 650 ° C. or less.

(2) In mol%,
La ₂ O ₃ component 0 to 30.0%,
Gd ₂ O ₃ component 0 to 15.0%,
TiO ₂ component 0-35.0%,
Nb ₂ O ₅ component 0 to 20.0%,
WO ₃ component 0-10.0%,
Li ₂ O component 0 to 10.0%,
ZrO ₂ component 0 to 15.0%
The optical glass according to (1).

(3) In mol%,
Y ₂ O ₃ component 0 to 30.0%,
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%,
SiO ₂ component 0 to 30.0%,
MgO component 0 to 15.0%,
CaO component 0 to 20.0%,
SrO component 0 to 15.0%,
BaO component 0 to 25.0%,
P ₂ O ₅ component 0 to 15.0%,
GeO ₂ component 0 to 15.0%,
Ta ₂ O ₅ component 0 to 10.0%,
Al 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 a molar sum (Gd ₂ O ₃ + Y ₂ O ₃ ) is 30.0% or less.

(5) The optical glass according to any one of (1) to (4), wherein a molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 10.0% or more and 40.0% or less.

(6) The optical glass according to any one of (1) to (5), wherein the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is 0.50 or more and 10.00 or less.

(7) The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 1.0% or more and 35.0% or less,
The optical component according to any one of (1) to (6), wherein the molar sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 10.0% or less. Glass.

  (8) The optical glass according to any one of (1) to (7), wherein a molar sum (CaO + ZnO) is 1.0% or more and 30.0% or less.

  (9) Any one of (1) to (8), wherein the refractive index (nd) and the Abbe number (νd) satisfy a relationship of (−0.02νd + 2.50) ≦ nd ≦ (−0.02νd + 2.60) Optical glass.

  (10) The optical glass according to any one of (1) to (9), wherein the specific gravity is 5.50 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 molding comprising the optical glass according to any one of (1) to (10).

  (13) An optical element obtained by precision pressing the preform described in (12).

According to the present invention, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range, a low glass transition point, suitable for press molding, and high devitrification resistance; A preform and an optical element using the same can be provided.
In addition, according to the present invention, it is possible to obtain an optical glass having high visible light transmittance and low specific gravity while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. it can.

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

The optical glass of the present invention is mol%, the B ₂ O ₃ component is 10.0% to 50.0% and the Ln ₂ O ₃ component is 10.0% to 35.0% (wherein Ln is 1 or more selected from the group consisting of La, Gd, Y, and Yb), and a ZnO component in an amount of 1.0 to 35.0%, and a refractive index (nd) of 1.80 to 2.20. And an Abbe number (νd) of 25 or more and 38 or less and a glass transition point (Tg) of 650 ° C. or less. According to the present invention, when a ZnO component is used in combination with the B ₂ O ₃ component and the Ln ₂ O ₃ component, the glass transition point is low and stable while obtaining a desired high refractive index and high dispersion. High-performance glass 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 may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

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

<About essential and optional components>
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 10.0% or more of the B ₂ O ₃ component, the devitrification resistance of the glass can be enhanced and the specific gravity can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 15.0%, still more preferably 19.0%, still more preferably 20.0%, and even more preferably 22.0%. Is the lower limit.
On the other hand, by setting the content of the B ₂ O ₃ component to 50.0% or less, a decrease in refractive index and an increase in Abbe number can be suppressed, and a deterioration in chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 50.0%, more preferably 44.0%, still more preferably 41.0%, and even more preferably 38.0%.
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 sum (molar sum) of the contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is 10.0% or more and 35.0% or less Is preferred.
In particular, by setting the molar sum to 10.0% or more, the refractive index of the glass can be increased, so that a high refractive index glass can be easily obtained. Therefore, the molar sum of the contents of the Ln ₂ O ₃ component is preferably 10.0% or more, more preferably more than 13.0%, still more preferably more than 16.0%, still more preferably more than 17.0%. To do.
On the other hand, by setting the molar sum to 35.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. In addition, this can suppress an increase in the Abbe number and reduce the material cost of the glass. Therefore, the molar sum of the contents of the Ln ₂ O ₃ component is preferably 35.0% or less, more preferably less than 28.0%, even more preferably less than 25.0%, still more preferably less than 23.0%. More preferably, it is less than 21.0%.

By containing 1.0% or more of the ZnO component, the glass transition point can be lowered, the specific gravity can be reduced, and the chemical durability can be increased. Therefore, the content of the ZnO component is preferably 1.0% or more, more preferably 2.5% or more, further preferably more than 4.0%, more preferably more than 5.0%, and still more preferably 8.0. %, More preferably more than 10.0%.
On the other hand, by making the content of the ZnO component 35.0% or less, it is possible to reduce the refractive index and devitrification. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striae to glass can be reduced. Accordingly, the content of the ZnO component is preferably 35.0% or less, more preferably less than 28.0%, even more preferably 26.0% or less, still more preferably less than 23.0%, still more preferably 19.0. %, More preferably less than 16.5%.
As the ZnO component, ZnO, ZnF ₂ 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 when it contains more than 0%. Further, by containing a La ₂ O ₃ component, since the content of other rare earth elements to increase the specific gravity is reduced, it can more easily obtain a glass having a small specific gravity. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably 3.0%, even more preferably 5.0%, still more preferably 8.5%, and even more preferably 13. It may be more than 0%.
On the other hand, by setting the content of the La ₂ O ₃ component to 30.0% or less, the stability of the glass can be increased, 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%, more preferably 25.0%, still more preferably 20.0%, and even more preferably less than 19.0%.
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 Gd ₂ O ₃ component is an optional component that can increase the refractive index of the glass and increase the devitrification resistance when it contains at least one of more than 0%. Accordingly, the content of the Gd ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, and even more preferably 1.45%.
On the other hand, by setting the content of the Gd ₂ O ₃ component to 15.0% or less, the devitrification resistance can be increased and the increase in the Abbe number can be suppressed. In particular, the material cost of glass can be suppressed by reducing the content of the Gd ₂ O ₃ component. Accordingly, the content of the Gd ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, even more preferably less than 7.0%, still more preferably less than 4.0%, and even more preferably. 3.5% 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 TiO ₂ component is an optional component that can increase the refractive index, lower the Abbe number, reduce the specific gravity, and increase the stability when it is contained in an amount of more than 0%. Accordingly, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 4.0%, still more preferably more than 6.0%, still more preferably 9.0%. More preferably, it may be more than 11.0%.
On the other hand, by setting the content of the TiO ₂ component to 35.0%, the coloring of the glass is reduced, the visible light transmittance is increased, and the Abbe number is reduced more than necessary. Further, devitrification due to excessive inclusion of the TiO ₂ component can be suppressed. Therefore, the content of the TiO ₂ component is preferably 35.0%, more preferably 30.0%, further preferably 27.0%, and further preferably 24.0%.
As the TiO ₂ component, TiO ₂ 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 and decrease the Abbe's number and increase the devitrification resistance when it exceeds 0%. Accordingly, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably more than 0.5%, even more preferably more than 1.0%, and even more preferably more than 1.5%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 20.0% or less, a decrease in devitrification resistance and a decrease in visible light transmittance due to an excessive content of the Nb ₂ O ₅ component are suppressed. It is done. In addition, this makes it possible to reduce the specific gravity of the glass and to suppress the material cost. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, still more preferably 11.0%.
As the Nb ₂ O ₅ component, Nb 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 lower the Abbe number, lower the glass transition point, and increase the devitrification resistance when it contains more than 0%. Therefore, the content of the WO ₃ component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, and even more preferably more than 1.3%.
On the other hand, by making the content of the WO ₃ component 10.0% or less, the transmittance of glass against visible light can be made difficult to decrease, and the material cost can be suppressed. Accordingly, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 8.0%, even more preferably less than 6.0%, still more preferably less than 5.0%, and still more preferably 4.%. Less than 0%.
As the WO ₃ component, WO ₃ 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 it contains more than 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably 0.7% or more, further preferably more than 1.0%, still more preferably 1.5% or more, and further preferably 2.2%. % Or more.
On the other hand, by making the content of the Li ₂ O component 10.0% or less, it is possible to reduce the refractive index and devitrification, and to improve the chemical durability. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striae to glass can be reduced. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably less than 8.0%, still more preferably less than 5.0%, and even more preferably less than 4.0%.
For the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can contribute to an increase in the refractive index of the glass and can improve the devitrification resistance when it is contained in excess of 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 2.0%.
On the other hand, by setting the ZrO ₂ component to 15.0% or less, an increase in Abbe number and a decrease in devitrification resistance due to excessive inclusion of the ZrO ₂ component can be suppressed. Accordingly, the upper limit of the content of the ZrO ₂ component is preferably 15.0%, more preferably 12.0%, still more preferably 10.0%, and even more preferably 8.5%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

Y ₂ O ₃ component and Yb ₂ O ₃ component, when 0% ultra containing one at least, an elevated refractive index of the glass, and is an optional component that enhances devitrification resistance.
On the other hand, devitrification due to excessive inclusion is reduced by making the content of the Y ₂ O ₃ component 30.0% or less, or by making the content of the Yb ₂ O ₃ component 10.0% or less. And the increase in Abbe number can be suppressed. In particular, the material cost of the glass can be suppressed by reducing the content of the Yb ₂ O ₃ component. Therefore, the content of the Y ₂ O ₃ component is preferably 30.0% or less, more preferably less than 20.0%, and even more preferably less than 10.0%. The content of the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 7.0%, further preferably less than 4.0%, and more preferably less than 2.0%.
As Y ₂ O ₃ component and Yb ₂ O ₃ component, Y ₂ O ₃ , YF ₃ , Yb ₂ O _{3 and the} like can be used as raw materials.

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 contains more than 0%. is there.
On the other hand, by making each content of the Na ₂ O component and the K ₂ O component 10.0% or less, the refractive index can be hardly lowered and devitrification due to excessive inclusion can be reduced. Therefore, the content of each of the Na ₂ O component and the K ₂ O component is preferably 10.0% or less, more preferably less than 5.0%, and even more preferably less than 3.0%.
The Na ₂ O component and the K ₂ O component may use 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. as raw materials. it can.

When the SiO ₂ component is contained in an amount exceeding 0%, the viscosity of the molten glass can be increased, the coloring of the glass can be reduced, and the devitrification resistance can be increased. Accordingly, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 2.0%, still more preferably more than 3.0%, still more preferably 4.0%. It may be super.
On the other hand, by setting the content of the SiO ₂ component to 30.0% or less, a decrease in the refractive index can be suppressed, an increase in the glass transition point can be suppressed, and the specific gravity can be reduced. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 30.0%, more preferably 20.0%, still more preferably 17.0%, still more preferably 14.0%.
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 MgO component, CaO component and SrO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when at least one of them contains more than 0%. In particular, the MgO component and the CaO component are components that can reduce the specific gravity by containing them.
On the other hand, by making the respective contents of the MgO component and the SrO component 15.0% or less, a decrease in refractive index and devitrification due to excessive inclusion of these components can be reduced. Therefore, the content of each of the MgO component and the SrO component is preferably 15.0% or less, more preferably less than 10.0%, more preferably 8.5% or less, and even more preferably less than 5.0%. .
Moreover, the fall of the refractive index and devitrification by excess containing of these components can be reduced by making content of a CaO component 20.0% or less. Therefore, the content of the CaO component is preferably 20.0% or less, more preferably 15.0% or less, still more preferably less than 10.0%, more preferably 8.5% or less, and still more preferably 5.0. %.
For the MgO component, CaO component, and SrO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

The BaO component is an optional component that can suppress the material cost while increasing the refractive index of the glass and can increase the meltability and devitrification resistance of the glass raw material when it contains more than 0%.
On the other hand, by setting the content of the BaO component to 25.0% or less, devitrification due to excessive inclusion and an increase in specific gravity can be suppressed. Accordingly, the upper limit of the content of the BaO component is preferably 25.0%, more preferably 20.0%, and even more preferably 15.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ 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 devitrification resistance.
On the other hand, by setting the content of the P ₂ O ₅ component to 15.0% or less, it is possible to suppress a decrease in chemical durability, particularly water resistance, of the glass. Therefore, the content of the P ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, and still more preferably less than 5.0%.
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 of the glass and increase the devitrification resistance when it is contained in an amount of more than 0%.
However, since GeO ₂ has a high raw material price, a large amount of GeO ₂ increases the material cost of glass. 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%, and still more preferably less than 2.0%.
As the GeO ₂ component, GeO 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, increase the devitrification resistance, and increase the viscosity of the molten glass when it is contained in excess of 0%.
On the other hand, when the content of the Ta ₂ O ₅ component is 10.0% or less, the amount of the Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, so that the glass material cost can be reduced. Moreover, specific gravity can be made small by this. 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 2.0%, and most preferably not contained.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Al ₂ O ₃ component is an optional component that can improve chemical durability and devitrification resistance when it exceeds 0%.
On the other hand, by setting the content of the Al ₂ O ₃ component to 15.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of the Al ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably less than 5.0%.
As the Al ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and decrease 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, the devitrification resistance of the glass can be increased, and the coloring of the glass can be reduced to increase the visible light transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 8.0%, still more preferably less than 5.0%, 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 and lower the glass transition point when it is contained in excess of 0%.
On the other hand, when the content of the TeO ₂ component is 15.0% or less, the coloring of the glass is reduced and the visible light transmittance can be increased. Further, TeO ₂ has a problem that it can be alloyed with platinum when melting a glass raw material in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, 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 increase the visible light transmittance of the glass while clarifying by reducing oxidation of the molten glass when it contains more than 0%.
On the other hand, by setting the content of the SnO ₂ component to 5.0% or less, the coloring of the glass due to the reduction of the molten glass and the devitrification of the glass can be reduced. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%.
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 an optional component that can degas the molten glass when it contains more than 0%.
On the other hand, when the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region is deteriorated. Accordingly, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.5%, and still more preferably 0.3%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

As the component which clarified defoaming glass, 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 sum (molar sum) of the contents of the Gd ₂ O ₃ component and the Y ₂ O ₃ component is preferably 30.0% or less.
Thereby, it is possible to suppress an increase in Abbe number and an increase in glass material cost due to excessive inclusion of these components. Accordingly, the molar sum (Gd ₂ O ₃ + Y ₂ O ₃ ) is preferably not more than 30.0%, more preferably less than 20.0%, still more preferably less than 15.0%, still more preferably less than 10.0%. More preferably, the content is less than 5.0%.
On the other hand, when this sum exceeds 0%, the stability of the glass is increased, and thus devitrification can be suppressed. Therefore, the molar sum (Gd ₂ O ₃ + Y ₂ O ₃ ) is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, and even more preferably more than 1.45%. Good.

The sum (molar sum) of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 10.0% or more and 40.0% or less.
In particular, by setting the sum to 10.0% or more, the refractive index increases and the stability of the glass increases, so that an optical glass having a high refractive index and high dispersion can be easily obtained. Accordingly, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 10.0% or more, more preferably more than 12.0%, more preferably more than 14.0%, still more preferably more than 16.0%. More preferably, it is more than 17.5%, more preferably more than 20.0%.
On the other hand, by making this sum 40.0% or less, coloring and devitrification of glass due to excessive inclusion of these components can be reduced. Therefore, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 40.0%, more preferably 35.0%, still more preferably 30.0%, and even more preferably 28.0%. .

Content of TiO ₂ component, Nb ₂ O ₅ component and WO ₃ component with respect to content of Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y and Yb) The sum ratio (molar ratio) is preferably 0.50 or more and 10.00 or less.
In particular, by setting this ratio to 0.50 or more, the refractive index increases and the stability of the glass increases, so that an optical glass having a high refractive index and high dispersion can be easily obtained. Therefore, the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is preferably 0.50, more preferably 0.65, still more preferably 0.75, and still more preferably 1.00. To do.
On the other hand, by setting this ratio to 10.00 or less, resistance to devitrification can be improved and transmittance in a short wavelength region of the visible light region can be increased. Therefore, the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is preferably 10.00, more preferably 7.00, still more preferably 4.00, and even more preferably 2.00. To do.

The sum (molar sum) of the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) is 1.0% or more and 35.0% or less. preferable.
In particular, by making this sum 1.0% or more, the meltability of the glass raw material and the devitrification resistance of the glass can be enhanced. Therefore, the total content of RO components is preferably 1.0%, more preferably 2.5%, further preferably 5.0%, more preferably 8.0%, and still more preferably 9.5%. And more preferably over 10.0%.
On the other hand, by making this sum 35.0% or less, devitrification due to excessive inclusion of these components can be reduced, and a decrease in refractive index can be suppressed. Therefore, the total content of RO components is preferably 35.0% or less, more preferably less than 30.0%, even more preferably less than 28.0%, still more preferably less than 25.0%, and even more preferably 22. It is less than 0%, more preferably less than 19.0%, and even more preferably less than 16.5%.

The sum (molar sum) of the content of Rn ₂ O components (wherein Rn is at least one selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. Thereby, the fall of the refractive index of glass can be suppressed and devitrification can be reduced. Therefore, the molar sum of the contents of the Rn ₂ O component is preferably 10.0% or less, more preferably less than 8.0%, and even more preferably less than 5.0%.
On the other hand, the sum (molar sum) of the contents of the Rn ₂ O component may be more than 0%. Thereby, devitrification resistance can be improved and a glass transition point can be made low. Therefore, the molar sum of the contents of the Rn ₂ O component is preferably more than 0%, more preferably 0.8%, still more preferably 1.1%, still more preferably 1.5%, still more preferably 2.2%. % May be the lower limit.

The sum (mol sum) of the contents of the CaO component and the ZnO component is preferably 1.0% or more and 30.0% or less.
In particular, by making this sum 1.0% or more, the specific gravity can be reduced and the glass transition point can be lowered. Therefore, the molar sum (CaO + ZnO) is preferably 1.0%, more preferably 2.2%, still more preferably 4.0%, still more preferably 5.0%, still more preferably 8.0%, still more preferably Has a lower limit of 9.5%, more preferably more than 10.0%.
On the other hand, by making this sum 30.0% or less, devitrification due to excessive inclusion of these components can be reduced, and a decrease in refractive index can be suppressed. Therefore, the molar sum (CaO + ZnO) is preferably 30.0%, more preferably 27.0%, still more preferably 25.0%, still more preferably 20.0%, still more preferably 17.0%. To do.

<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 poured into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, and then a platinum crucible, a platinum alloy After putting in a crucible or iridium crucible for 3 to 5 hours in a temperature range of 1100 to 1400 ° C., stirring and homogenizing to eliminate bubbles, etc., the temperature is lowered to 1000 to 1300 ° C. It is produced by removing the reason, casting it in a mold and slowly cooling it.

<Physical properties>
The optical glass of the present invention has a high refractive index and a high Abbe number (low dispersion).
In particular, the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.80, more preferably 1.85, more preferably more than 1.87, and even more preferably more than 1.91. The upper limit of this refractive index is preferably 2.20, more preferably 2.10, still more preferably 2.05, still more preferably 2.00, and even more preferably 1.97. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 25, more preferably 27, still more preferably 28, the lower limit, preferably 38, more preferably 36, still more preferably 34, the upper limit, More preferably, it is less than 33.
Since the optical glass of the present invention has such a refractive index and Abbe number, it is useful in optical design, and the optical system can be downsized while achieving particularly high imaging characteristics and the like. The degree of freedom can be expanded.

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 (−0.02νd + 2.50) ≦ nd ≦ (−0.02νd + 2.60). In the glass having the composition specified by the present invention, a more stable glass can be obtained when the refractive index (nd) and the Abbe number (νd) satisfy this relationship.
Therefore, in the optical glass of the present invention, the refractive index (nd) and the Abbe number (νd) preferably satisfy the relationship of nd ≧ (−0.02νd + 2.50), and nd ≧ (−0.02νd + 2.51). Is more preferable, and it is more preferable to satisfy the relationship of nd ≧ (−0.02νd + 2.52).
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 ≦ (−0.02νd + 2.60)), and nd ≦ (−0.02νd + 2. 59)) is more preferable, and nd ≦ (−0.02νd + 2.58)) is more preferable.

The optical glass of the present invention has a glass transition point of 650 ° C. or lower. Thereby, since glass softens at lower temperature, glass can be press-molded at lower temperature. Further, it is possible to extend the life of the mold by reducing oxidation of the mold used for mold press molding. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 650 ° C., more preferably 630 ° C., further preferably 620 ° C., more preferably 615 ° C.
The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 460 ° C, more preferably 500 ° C, and even more preferably 550 ° C. Good.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high transmittance of light on the short wavelength side of visible light, and thereby less coloring.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 500 nm, more preferably 480 nm, still more preferably 460 nm, More preferably, the upper limit is 450 nm, and more preferably 420 nm.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) having a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, and still more preferably 370 nm.
As a result, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

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 5.50 or less. Thereby, since the mass of an optical element and an optical apparatus using the same is reduced, it can contribute to the weight reduction of an optical apparatus. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.50, more preferably 5.30, still more preferably 5.10, still more preferably 5.00, and still more preferably 4.90. The specific gravity of the optical glass of the present invention is generally about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more in many cases.
The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 “Measurement Method of Specific Gravity of Optical Glass”.

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

[Glass molding and optical element]
A glass molded body can be produced from the produced optical glass by means of, for example, polishing or molding press molding such as reheat press molding or precision press molding. That is, a glass molded body is manufactured by performing mechanical processing such as grinding and polishing on optical glass, or glass molding is performed by performing a polishing process after performing reheat press molding on a preform manufactured from optical glass. A glass molded body can be produced by producing a body, or by performing precision press molding on a preform produced by polishing or a preform formed by known float forming or the like. In addition, the means for producing the glass molded body 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 them for optical elements such as lenses and prisms. This makes it possible to form a glass molded body with a large diameter, so that the optical elements can be enlarged, but with high definition and high precision imaging characteristics and projection when used in optical equipment such as cameras and projectors. The characteristics can be realized.

Composition of Examples (No. 1 to No. 64) and Comparative Example (No. A) of the present invention, refractive index (n _d ), Abbe number (ν _d ), glass transition point (Tg), spectral transmission Tables 1 to 9 show the wavelengths (λ ₅ , λ ₇₀ ) and specific gravity at which the rates indicate 5% and 70%.
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, mixed uniformly, and then put into a platinum crucible, depending on the melting difficulty of the glass composition. After melting in an electric furnace in the temperature range of 1100 to 1400 ° C. for 3 to 5 hours, stirring and homogenizing to remove bubbles, etc., the temperature is lowered to 1000 to 1300 ° C. and stirring and homogenizing, and then cast into a mold. The glass was produced by slow cooling.

The refractive index (n _d ) and Abbe number (ν _d ) of the glass of the examples and comparative examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, from the value of the refractive index obtained _{(n d)} and Abbe number ([nu _d), in relation _{n d = -a × ν d +} b, the slope a is determined intercept b when the 0.02.
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 glass transition point (Tg) of the glass of Examples and Comparative Examples is determined by measuring the relationship between temperature and sample elongation according to the Japan Optical Glass Industry Association Standard JOGIS08-2003 “Measurement Method of Thermal Expansion of Optical Glass”. It calculated | required from the obtained thermal expansion curve.

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. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (transmittance). Wavelength at 70%).

The specific gravity of the glass of an Example and a comparative example was measured based on Japan Optical Glass Industry Association standard JOGIS05-1975 "measurement method of specific gravity of optical glass".

As shown in these tables, since the optical glass of the examples of the present invention has a glass transition point of 650 ° C. or lower, more specifically 620 ° C. or lower, it is presumed that the glass can be molded and pressed at a lower temperature.
On the other hand, the glass of the comparative example has a glass transition point of 698 ° C., which exceeds 650 ° C.
Therefore, the optical glass of the Example of this invention has a low glass transition point compared with the glass of a comparative example, and it became clear that it was suitable for press molding.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.80 or more, more specifically 1.91 or more, and this refractive index (n _d ) is 2.20 or less. More specifically, it was 1.97 or less, and was within the desired range.

The optical glasses of the examples of the present invention each have an Abbe number (ν _d ) of 25 or more, more specifically 28 or more, and this Abbe number (ν _d ) of 38 or less, more specifically 32. And within the desired range.

In the optical glass of the example of the present invention, the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (−0.02νd + 2.50) ≦ nd ≦ (−0.02νd + 2.60). More specifically, the relationship (−0.02νd + 2.51) ≦ nd ≦ (−0.02νd + 2.58) was satisfied. The relationship between the refractive index (nd) and the Abbe number (νd) of the glass of the example of the present application is as shown in FIG.
These optical glasses were stable glasses that were not devitrified.
On the other hand, the glass of the comparative example had an Abbe number (ν _d ) of 41.5 and exceeded 38.
For this reason, it becomes clear that the optical glass of the example of the present invention has a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, and a highly stable optical glass can be obtained. It was.

  The optical glasses of the examples of the present invention all had a specific gravity of 5.50 or less, more specifically 5.00 or less, and were within a desired range.

In addition, in the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 500 nm or less, and more specifically, 460 nm or less. The optical glasses of the examples of the present invention all had λ ₅ (wavelength at a transmittance of 5%) of 400 nm or less, more specifically 370 nm or less. For this reason, 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.

Therefore, the optical glass of the example of the present invention has a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, a low glass transition point, suitable for press molding, and high stability. It became clear that an optical glass having a high transmittance for visible light and a small specific gravity can be obtained.

  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 (13)

In mol%, the B ₂ O ₃ component is 10.0% or more and 50.0% or less, and the Ln ₂ O ₃ component is 10.0% or more and 35.0% or less (wherein Ln is La, Gd, Y, Yb 1 or more selected from the group consisting of) and ZnO component in an amount of 1.0 to 35.0%, a refractive index (nd) of 1.80 or more and 2.20 or less, and 25 or more and 38 or less. An optical glass having an Abbe number (νd) and a glass transition point (Tg) of 650 ° C. or lower. In mol%
La ₂ O ₃ component 0 to 30.0%,
Gd ₂ O ₃ component 0 to 15.0%,
TiO ₂ component 0-35.0%,
Nb ₂ O ₅ component 0 to 20.0%,
WO ₃ component 0-10.0%,
Li ₂ O component 0 to 10.0%,
ZrO ₂ component 0 to 15.0%
The optical glass according to claim 1. In mol%
Y ₂ O ₃ component 0 to 30.0%,
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%,
SiO ₂ component 0 to 30.0%,
MgO component 0 to 15.0%,
CaO component 0 to 20.0%,
SrO component 0 to 15.0%,
BaO component 0 to 25.0%,
P ₂ O ₅ component 0 to 15.0%,
GeO ₂ component 0 to 15.0%,
Ta ₂ O ₅ component 0 to 10.0%,
Al 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 claim 1 or 2. 4. The optical glass according to claim 1, wherein a molar sum (Gd ₂ O ₃ + Y ₂ O ₃ ) is 30.0% or less. _5. The optical glass according to claim 1, wherein a molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 10.0% or more and 40.0% or less. 6. The optical glass according to claim 1, wherein the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is 0.50 or more and 10.00 or less. The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 1.0% or more and 35.0% or less,
The optical glass according to any one of claims 1 to 6, wherein a molar sum of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 10.0% or less.   The optical glass according to any one of claims 1 to 7, wherein a molar sum (CaO + ZnO) is 1.0% or more and 30.0% or less.   The optical glass according to claim 1, wherein the refractive index (nd) and the Abbe number (νd) satisfy a relationship of (−0.02νd + 2.50) ≦ nd ≦ (−0.02νd + 2.60).   The optical glass according to claim 1, having a specific gravity of 5.50 or less.   An optical element made of the optical glass according to claim 1.   A preform for polishing and / or precision press molding comprising the optical glass according to claim 1.   An optical element obtained by precision pressing the preform according to claim 12.

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