TW201817691A - Optical glass, preform, and optical element having high refractive index, low Abbe number, and compact size - Google Patents

Abstract

An object of the present invention is to obtain an optical glass having a refractive index (nd) and Abbe number (vd) in a desired range at a low cost. The solution for the present invention is that the optical glass is composed of a B2O3 containing 6.0% or more and 30.0% or less, a La2O3 component that is 25.0% or more and 55.0% or less, a TiO2 component that is 6.0% or more and 25.0% or less, and a BaO component that is 4.0% or more and 27.0% or less in terms of mass%; the ZnO component has a content of 23.0% or less; a refractive index (nd) of 1.85 or more, and an Abbe number (νd) of 25 or more and 35 or less.

Description

   Optical glass, preform and optical element   

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

In recent years, the digitization or high definition of devices using optical systems has rapidly progressed, and has been reduced in the fields of various optical devices such as photographing equipment such as digital cameras and video cameras, image playback (projection) equipment such as projectors and projection televisions. The number of optical elements such as lenses or chirps used in optical systems is increasing the demand for lightening and miniaturizing the entire optical system.

Especially in the production of optical glass for optical elements, it is desired to reduce the weight and size of the entire optical system. The demand for high-refractive-index and high-dispersion glass with the following characteristics is very high: a high-refractive index (n _d ) of 1.85 or more , Low Abbe number (ν _d ) from 25 to 35. As such a high-refractive-index low-dispersion glass, a glass composition as shown in patent document 1 is known.

(Prior technical literature)

(Patent Literature)

Patent Document 1: Japanese Patent Application Laid-Open No. 2015-020913.

In order to reduce the material cost of optical glass, the raw material cost of optical glass is expected to be as cheap as possible. However, it is difficult to say that the glass described in Patent Document 1 can sufficiently satisfy such requirements.

In view of the foregoing problems, an object of the present invention is to obtain an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range at a lower cost.

In order to solve the above problems, the present inventors have worked hard to study the results of repeated experiments and found that in addition to the B ₂ O ₃ component and the La ₂ O ₃ component, when at least the TiO ₂ component and the BaO component are used in combination, not only the required high refractive index can be obtained The present invention achieves a high dispersion rate and a glass with suppressed material cost, thereby completing the present invention.

Specifically, the present invention provides the following.

(1) An optical glass containing, by mass%, a B ₂ O ₃ component of 6.0% to 30.0%, a La ₂ O ₃ component of 25.0% to 55.0%, and a TiO ₂ component of 6.0% to 25.0%. And a BaO component of 4.0% to 27.0%; a ZnO component content of 23.0% or less; a refractive index (n _d ) of 1.85 or more; and an Abbe number (ν _d ) of 25 or more and 35 or less.

(2) (1) of the optical glass described, which system comprises, in mass% of the following elements: from 0 to 13.0% of the SiO ₂ component, 0 to 10.0% of Gd ₂ O ₃ component, from 0% to 20.0 % Y ₂ O ₃ component, 0% to 10.0% Yb ₂ O ₃ component, 0% to 15.0% Nb ₂ O ₅ component, 0% to 20.0% WO ₃ component, 0% to 15.0% ZrO ₂ Component, 0% to 5.0% Ta ₂ O ₅ component, 0% to 5.0% MgO component, 0% to 10.0% CaO component, 0% to 10.0% SrO component, 0% to 5.0% Li ₂ O Component, 0% to 10.0% Na ₂ O component, 0% to 10.0% K ₂ O component, 0% to 10.0% P ₂ O ₅ component, 0% to 10.0% GeO ₂ component, 0% to 10.0 % Al ₂ O ₃ component, 0% to 10.0% Ga ₂ O ₃ component, 0% to 10.0% Bi ₂ O ₃ component, 0% to 10.0% TeO ₂ component, 0% to 3.0% SnO ₂ Component and 0% to 1.0% of Sb ₂ O ₃ component; the content of F as a fluoride substituted with one or two or more of the foregoing elements as a part or all of the oxide is 0% by mass to 10.0% by mass %.

(3) The optical glass according to (1) or (2), wherein the mass sum (SiO ₂ + B ₂ O ₃ ) is 10.0% or more and 30.0% or less.

(4) The optical glass according to any one of (1) to (3), wherein the mass sum (TiO ₂ + ZnO) is 10.0% or more and 45.0% or less.

(5) The optical glass according to any one of (1) to (4), wherein the mass sum (BaO + ZnO) is 10.0% or more and 40.0% or less.

(6) The optical glass according to any one of (1) to (5), wherein the mass ratio TiO ₂ / SiO ₂ is 1.00 or more.

(7) The optical glass according to any one of (1) to (6), wherein the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O ₃ is 1.50 or less.

(8) The optical glass according to any one of (1) to (7), wherein the mass ratio BaO / Ln ₂ O ₃ is 0.0400 or more and 0.5000 or less, where Ln is composed of La, Gd, Y, Yb 1 or more selected from the group.

(9) The optical glass according to any one of (1) to (8), wherein the mass ratio (SiO ₂ + BaO) / ZnO is 8.00 or less.

(10) The optical glass according to any one of (1) to (9), wherein the mass ratio (Ln ₂ O ₃ + TiO ₂ + ZnO) / (SiO ₂ + B ₂ O ₃ ) is 2.00 or more and 5.00 or less In the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb.

(11) The optical glass according to any one of (1) to (10), wherein the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 5.0% or more and 25.0% or less.

(12) The optical glass according to any one of (1) to (11), wherein the mass ratio TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 0.600 or more and 1.000 or less.

(13) The optical glass according to any one of (1) to (12), wherein the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 1.00 or more and 3.00 or less, and the mass ratio (B ₂ O ₃ + ZnO) / SiO ₂ is 1.50 or more and 5.00 or less.

(14) The optical glass according to any one of (1) to (13), wherein the mass sum (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) is 10.0% or less.

(15) The optical glass according to any one of (1) to (14), wherein the mass ratio (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) / (TiO ₂ + ZnO) is 0.500 or less .

(16) The optical glass according to any one of (1) to (15), wherein the mass sum (CaO + SrO) is 10.0% or less.

(17) The optical glass according to any one of (1) to (16), wherein the mass%: the sum of the content of the RO component is 10.0% or more and 40.0% or less, wherein R is represented by Mg, Ca, One or more selected from the group consisting of Sr, Ba, and Zn; the sum of the content of the Rn ₂ O component is 10.0% or less, where Rn is the selected one from the group consisting of Li, Na, and K One or more types; the sum of the contents of the Ln ₂ O ₃ components is 25.0% or more and 54.0% or less, where Ln is one or more types selected from the group consisting of La, Gd, Y, and Yb.

(18) A preformed structure composed of the optical glass according to any one of (1) to (17).

(19) An optical element composed of the optical glass according to any one of (1) to (17).

(20) An optical device comprising the optical element according to (19).

With the present invention, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range can be obtained at a lower cost.

In addition, according to the present invention, an optical glass having not only a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range, high stability, high transmittance to visible light, and small specific gravity can be obtained.

FIG. 1 is a graph showing the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) of the glass according to the examples (No. A1 to No. A29) of the present application.

FIG. 2 is a graph showing the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) of the glass according to the examples (No. B1 to No. B30) of the present application.

The optical glass of the present invention contains, by mass%, a B ₂ O ₃ component of 6.0% to 30.0%; a La ₂ O ₃ component of 25.0% to 55.0%; a TiO ₂ component of 6.0% to 25.0%; A BaO component of 4.0% or more and 27.0% or less; a ZnO component content of 23.0% or less; a refractive index (n _d ) of 1.85 or more and an Abbe number (ν _d ) of 25 or more and 35 or less.

Among them, the first optical glass contains, by mass%, a B ₂ O ₃ component of 6.0% to 30.0%; a La ₂ O ₃ component of 25.0% to 50.0%; a TiO ₂ component of 6.0% to 25.0%; ZnO component of 2.0% or more and 23.0% or less; BaO component of 4.0% or more and 22.0% or less; has a refractive index (n _d ) of 1.85 or more, and an Abbe number (ν _d ) of 25 or more and 35 or less.

In addition, the second optical glass contains, by mass%, a B ₂ O ₃ component of 7.0% to 30.0%; a La ₂ O ₃ component of 25.0% to 55.0%; a TiO ₂ component of 7.0% to 25.0%; BaO component greater than 6.0% and 27.0% or less; ZnO component content is 16.0% or less; has a refractive index (n _d ) of 1.85 or more, and an Abbe number (ν _d ) of 25 or more and 35 or less.

According to the present invention, in addition to the B ₂ O ₃ component and the La ₂ O ₃ component, at least when a TiO ₂ component and a BaO component are used in combination, not only the required high refractive index and high dispersion can be obtained, but also the material cost can be suppressed. Of glass.

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 may be implemented with appropriate changes within the scope of the object of the present invention. In addition, although the description may be appropriately omitted in the overlapping description, the spirit of the invention is not limited.

[Glass composition]

The composition range of each component which comprises the optical glass of this invention is as follows. In this specification, unless specifically specified, the content of each component is expressed in terms of mass% relative to the total mass of the glass in terms of the oxide conversion composition. Here, the "oxide conversion composition" refers to the case where oxides, complex salts, metal fluorides, and the like used as raw materials of the glass constituents of the present invention are assumed to be completely decomposed during melting to become oxides. The total mass of the produced oxide was 100% by mass, and the composition of each component contained in the glass was marked.

<About essential ingredients, optional ingredients>

The B ₂ O ₃ component is an indispensable component as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxides.

In particular, by ₂ O ₃ component contains 6.0% B, and improved resistance to devitrification of the glass, and reduces the specific gravity. Therefore, the content of the B ₂ O ₃ component is preferably 6.0% or more, more preferably 7.0% or more, still more preferably more than 8.5%, still more preferably more than 10.0%, still more preferably more than 10.5%, and more preferably Is greater than 12.0%.

On the other hand, with the content of B ₂ O ₃ component is set to 30.0% or less, and suppress the increase or decrease of the refractive index Abbe number, and to suppress the deterioration of chemical durability. Therefore, the content of the B ₂ O ₃ component is preferably 30.0% or less, more preferably 27.0% or less, still more preferably 24.0% or less, still more preferably 23.0% or less, still more preferably less than 20.0%, and more preferably It is less than 18.0%, more preferably less than 15.5%, and even more preferably less than 15.0%.

For 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 and the like can be used as raw materials.

The La ₂ O ₃ component is an essential component, and the refractive index can be increased by containing 25.0% or more. In addition, since the content of other rare-earth elements that increase the specific gravity can be reduced by containing the La ₂ O ₃ component, it is easier to obtain glass with a lower specific gravity. Therefore, the content of the La ₂ O ₃ component is preferably more than 25.0%, more preferably more than 28.0%, still more preferably more than 31.0%, still more preferably more than 34.0%, still more preferably more than 35.0%, and more preferably Is greater than 36.0%.

On the other hand, by setting the content of the La ₂ O ₃ component to 55.0% or less, it is possible to improve the stability of the glass, reduce devitrification, and suppress an increase in the Abbe number. Accordingly, the content of La ₂ O ₃ component is preferably 55.0% or less, more preferably 50.0% or less, and more preferably less than 50.0%, and more preferably less than 46.0%, and more preferably less than 43.0%, and more preferably It is less than 42.0%, and more preferably less than 40.0%.

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 TiO ₂ component is an essential component, and by containing 6.0% or more, it can increase the refractive index, reduce the Abbe number, reduce the specific gravity, and improve devitrification resistance. Therefore, the content of the TiO ₂ component is preferably 6.0% or more, more preferably 7.0% or more, more preferably more than 7.0%, still more preferably more than 8.0%, still more preferably more than 11.0%, and even more preferably more than 13.0%.

On the other hand, by setting the content of the TiO ₂ component to 25.0% or less, the coloration of the glass can be reduced, the visible light transmittance can be improved, and the Abbe number can be prevented from falling more than necessary. In addition, devitrification caused by containing excessive TiO ₂ components can be suppressed. Therefore, the content of the TiO ₂ component is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 18.0%, still more preferably 17.0% or less, and still more preferably 16.0% or less.

As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The BaO component is an essential component. By containing 4.0% or more, the refractive index of glass can be increased, the material cost can be suppressed, the meltability or devitrification resistance of glass raw materials can be improved, and the glass transition point can be reduced. Therefore, the content of the BaO component is preferably 4.0% or more, more preferably 5.0% or more, more preferably 6.0% or more, still more preferably 6.6% or more, more than 7.0%, or even more preferably 8.0 or more. %, More preferably 10.5% or more, and even more preferably 12.0% or more.

On the other hand, by setting the content of the BaO component to 27.0% or less, it is possible to suppress devitrification or an increase in specific gravity due to excessive content. Therefore, the content of the BaO component is preferably 27.0% or less, more preferably less than 24.0%, still more preferably 22.0% or less, still more preferably less than 20.0%, still more preferably less than 18.0%, and even more preferably less than 15.0. %, And more preferably less than 13.0%.

As the raw material for the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ and the like can be used.

The ZnO component is an arbitrary component, and when it contains more than 0%, it can reduce the glass transition point, reduce the specific gravity, and improve chemical durability. In particular, it can also be used as an essential component in the first optical glass. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 1.5%, still more preferably 2.0% or more, still more preferably 3.0% or more, still more preferably more than 3.0%, and even more preferably More than 5.0%, and more preferably more than 6.5%.

On the other hand, by reducing the content of the ZnO component to 23.0% or less, it is possible to reduce a decrease in refractive index or devitrification. In addition, since the viscosity of the molten glass can be increased, the occurrence of glass streaks can be reduced. Therefore, the content of the ZnO component is preferably 23.0% or less, more preferably less than 20.0%, still more preferably 16.0% or less, still more preferably less than 15.0%, still more preferably less than 13.0%, and even more preferably less than 11.0 %, More preferably 10.5% or less, still more preferably 9.5% or less, and even more preferably less than 8.0%.

As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The SiO ₂ component is an arbitrary component, and when it contains more than 0%, it can increase the viscosity of the molten glass, reduce the color of the glass, and improve the devitrification resistance. Therefore, the content of the SiO ₂ component is preferably greater than 0%, more preferably greater than 1.0%, still more preferably greater than 2.0%, still more preferably greater than 3.0%, still more preferably greater than 4.5%, and more preferably It is 6.3% or more, and more preferably 6.6% or more.

On the other hand, by setting the content of the SiO ₂ component to 13.0% or less, it is possible to suppress a decrease in the refractive index, a rise in the glass transition point, and a decrease in specific gravity. Therefore, the content of the SiO ₂ component is preferably 13.0% or less, more preferably less than 10.0%, and still more preferably less than 8.0%.

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 Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are arbitrary components. When at least one of them contains more than 0%, the refractive index of the glass can be increased and devitrification resistance can be improved.

On the other hand, by setting the content of each of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component to 10.0% or less, it is possible to reduce devitrification caused by excessively containing these components, suppress the increase in Abbe number, and suppress the glass Material costs. Therefore, the contents of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component are each preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably less than 2.0%, and even more preferably Less than 1.0%.

In addition, by setting the content of the Y ₂ O ₃ component to 20.0% or less, it is possible to reduce devitrification caused by excessively containing these components and suppress an increase in the Abbe number. Therefore, the content of the Y ₂ O ₃ component is preferably 20.0% or less, more preferably less than 10.0%, and even more preferably less than 5.0%.

As the Gd ₂ O ₃ component, Y ₂ O ₃ component, and Yb ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O _3, and the like can be used as raw materials.

The Nb ₂ O ₅ component is an arbitrary component. When the content is more than 0%, the refractive index can be increased, the Abbe number can be reduced, and devitrification resistance can be improved.

On the other hand, by reducing the content of the Nb ₂ O ₅ component to 15.0% or less, it is possible to suppress a decrease in devitrification resistance or a decrease in visible light transmittance caused by excessively containing the Nb ₂ O ₅ component. In addition, this can reduce the specific gravity of the glass and suppress the material cost. Therefore, the content of the Nb ₂ O ₅ component is preferably 15.0% or less, more preferably 10.0% or less, still more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, and more preferably Is less than 1.0%.

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 arbitrary component, and when it contains more than 0%, it can increase the refractive index, reduce the Abbe number, reduce the glass transition point, and improve devitrification resistance. Therefore, the content of the WO ₃ component is preferably greater than 0%, more preferably greater than 0.3%, and still more preferably greater than 0.5%.

On the other hand, by setting the content of the WO ₃ component to 20.0% or less, it is possible to make it difficult to reduce the transmittance of visible light to the glass and to suppress the material cost. Therefore, the content of the WO ₃ component is preferably 20.0% or less, more preferably 15.0% or less, still more preferably 10.0% or less, still more preferably less than 10.0%, still more preferably less than 5.0%, and even more preferably less than 3.0%, and more preferably less than 1.5%.

As the WO ₃ component, WO ₃ and the like can be used as a raw material.

The ZrO ₂ component is an arbitrary component, and when it contains more than 0%, it can contribute to a higher refractive index of the glass and improve devitrification resistance. Therefore, the content of the ZrO ₂ component is preferably greater than 0%, more preferably greater than 0.5%, still more preferably greater than 1.0%, still more preferably greater than 2.0%, and even more preferably greater than 4.0%.

On the other hand, by setting the ZrO ₂ component to 15.0% or less, it is possible to suppress an increase in the Abbe number or a decrease in devitrification resistance due to the excessive content of the ZrO ₂ component. Therefore, the content of the ZrO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably less than 8.0%.

For the ZrO ₂ component, ZrO ₂ , ZrF _4, or the like can be used as a raw material.

The Ta ₂ O ₅ component is an arbitrary component, and when it contains more than 0%, it can increase the refractive index, improve the devitrification resistance, and improve the viscosity of the molten glass.

On the other hand, since the content of the Ta ₂ O ₅ component is set to 5.0% or less, the amount of the Ta ₂ O ₅ component used as a rare mineral source can be reduced, thereby reducing the material cost of the glass. In addition, this can reduce the specific gravity. Therefore, the content of the Ta ₂ O ₅ component is preferably 5.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%, 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 MgO component, the CaO component, and the SrO component are arbitrary components, and when at least one of them contains more than 0%, the meltability of the glass raw material or the devitrification resistance of the glass can be improved. 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 containing the MgO component in an amount of 5.0% or less, it is possible to reduce a decrease in refractive index or devitrification caused by excessively containing these components. In addition, by reducing the content of each of the CaO component and the SrO component to 10.0% or less, it is possible to reduce a decrease in refractive index or devitrification caused by excessively containing these components. Therefore, the content of the MgO component is preferably 5.0% or less, more preferably less than 3.0%, and still more preferably less than 1.0%. The content of each of the CaO component and the SrO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

MgO component, CaO and SrO ingredients components may be used _{MgCO 3, MgF 2, CaCO 3} , CaF 2, Sr (NO 3) 2, SrF 2 , etc. as a raw material.

The Li ₂ O component is an arbitrary component, and when it contains more than 0%, it can improve the melting property of the glass and reduce the glass transition point.

On the other hand, when the content of the Li ₂ O component is set to 5.0% or less, it is possible to reduce a decrease in refractive index or devitrification and improve chemical durability. In addition, since the viscosity of the molten glass can be improved by this, the occurrence of glass streaks can be reduced. Therefore, the content of the Li ₂ O component is preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 1.0%, and even more preferably less than 0.5%.

As a Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are arbitrary components. When at least one of them contains more than 0%, the meltability of the glass raw material can be improved, the devitrification resistance can be improved, and the glass transition point can be reduced.

On the other hand, when the content of each of the Na ₂ O component and the K ₂ O component is set to 10.0% or less, it is not easy to reduce the refractive index, and it is possible to reduce devitrification due to excessive content. 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%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

As Na ₂ O component and 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 and the like can be used as raw materials.

The P ₂ O ₅ component is an optional component, and when it contains more than 0%, it can improve devitrification resistance.

On the other hand, by reducing the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, and particularly to suppress a decrease in water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ and the like can be used as raw materials.

The GeO ₂ component is an arbitrary component, and when it contains more than 0%, it can increase the refractive index of glass and improve devitrification resistance.

However, due to the high raw material prices of GeO _2, GeO ₂ in an amount to more than the material cost becomes high, TiO ₂ containing components will cancel, resulting in the cost of the ingredients, or BaO ZnO component reduction effect. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%, and most preferably not contained.

As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are arbitrary components, and when at least one of them contains more than 0%, chemical durability and devitrification resistance can be improved.

On the other hand, by setting the content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, devitrification caused by excessive content can be reduced. Thus, of Al ₂ O ₃ component, the content of Ga ₂ O ₃ component is preferably 10.0% or less each, more preferably less than 5.0%, and more preferably less than 3.0%, and more preferably less than 1.0%.

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 arbitrary component, and when it contains more than 0%, it can increase the refractive index, reduce the Abbe number, and lower the glass transition point.

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 improved, and the coloration 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 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an arbitrary component, and when it contains more than 0%, it can increase the refractive index and reduce the glass transition point.

On the other hand, by setting the content of the TeO ₂ component to 10.0% or less, the coloration of the glass can be reduced and the visible light transmittance can be improved. In addition, when the glass raw material is melted in a crucible made of platinum or a melting tank formed of platinum in a portion in contact with the molten glass, TeO ₂ has a problem of alloying with platinum. Therefore, the content of the TeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

As the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an arbitrary component. When the content of SnO ₂ is greater than 0%, the oxidation of the molten glass can be reduced and clarified, and the visible light transmittance of the glass can be improved.

On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to reduce the coloration or devitrification of the glass due to reduction of the molten glass. In addition, since the alloying of the SnO ₂ component and the melting equipment (especially noble metals such as Pt) is reduced, the life of the melting equipment can be expected to be longer. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, more preferably less than 1.0%, and still more preferably less than 0.5%.

As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ and the like can be used as a raw material.

The Sb ₂ O ₃ component is an arbitrary component, and when it contains more than 0%, the molten glass can be defoamed.

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. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, more preferably less than 0.5%, and still more preferably less than 0.1%.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O _7, 5H ₂ O, or the like can be used as a raw material.

Further, as a clear glass to be defoamed in terms of composition, it is not limited to the Sb ₂ O ₃ ingredients may be known in the glass making art clarifying agents, defoaming agents, or combinations of these.

The F component is an arbitrary component. When the content is greater than 0%, the Abbe number of the glass can be increased, the glass transition point can be reduced, and devitrification resistance can be improved.

However, if the content of the F component, that is, the total amount of F which is a fluoride substituted with one or two or more of the above-mentioned elements, or a part or all of the oxides, is greater than 10.0%, the volatile content of the F component changes. It is difficult to obtain a stable optical constant, and it is difficult to obtain a homogeneous glass. In addition, the Abbe number rose more than necessary.

Therefore, the content of the F component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.

The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

The sum (mass sum) of the content of the B ₂ O ₃ component and the SiO ₂ component is preferably 10.0% or more and 30.0% or less.

In particular, by setting the sum to 10.0% or more, devitrification due to lack of a B ₂ O ₃ component or a SiO ₂ component can be suppressed. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably more than 10.0%, more preferably more than 12.0%, still more preferably more than 15.0%, still more preferably more than 17.0%, and even more preferably more than 18.0%. .

On the other hand, by reducing the sum to 30.0% or less, it is possible to suppress a decrease in refractive index caused by excessively containing these components. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0% or less, more preferably less than 28.0%, still more preferably less than 25.0%, still more preferably less than 22.5%, and even more preferably less than 22.0. %.

The ratio (mass ratio) of the content of the SiO ₂ component to the content of the B ₂ O ₃ component is preferably less than 1.00. This makes it possible to suppress an increase in the glass transition point, and therefore, it is easier to perform low-temperature molding. Therefore, the mass ratio SiO ₂ / B ₂ O _{3 is} preferably less than 1.00, more preferably less than 0.80, still more preferably less than 0.56, and even more preferably less than 0.55.

On the other hand, the mass ratio SiO ₂ / B ₂ O ₃ may be larger than 0. Thereby, the stability of glass can be improved. Therefore, the mass ratio SiO ₂ / B ₂ O _{3 is} preferably more than 0, more preferably 0.1 or more, still more preferably 0.35 or more, and still more preferably 0.45 or more.

The ratio (mass ratio) of the content of the La ₂ O ₃ component to the content of the B ₂ O ₃ component is preferably greater than 0.60. Thereby, the refractive index of glass can be improved. Therefore, the mass ratio La ₂ O ₃ / B ₂ O _{3 is} preferably greater than 0.60, more preferably greater than 0.80, still more preferably greater than 1.00, still more preferably greater than 1.10, still more preferably greater than 1.50, and even more preferably More than 1.70, more preferably more than 2.00, still more preferably more than 2.30, and even more preferably more than 2.60.

On the other hand, the mass ratio La ₂ O ₃ / B ₂ O _{3 is} preferably less than 10.00, more preferably less than 7.00, still more preferably less than 5.00, still more preferably less than 4.00, and more preferably less than 3.70. , And more preferably less than 3.50, and even more preferably less than 3.40.

The sum (mass sum) of the contents of the TiO ₂ component and the ZnO component is preferably 10.0% or more and 45.0% or less.

In particular, by setting the sum to 10.0% or more, the stability of the glass can be improved and the refractive index can be improved. Therefore, the mass sum (TiO ₂ + ZnO) is preferably more than 10.0%, more preferably more than 12.0%, still more preferably more than 16.0%, still more preferably more than 16.5%, still more preferably more than 17.0%, and more It is preferably greater than 18.5%, and even more preferably greater than 19.0%.

On the other hand, the mass sum (TiO ₂ + ZnO) is preferably 45.0% or less, more preferably 40.0% or less, still more preferably 35.0% or less, still more preferably 30.0% or less, and still more preferably less than 30.0%, more preferably less than 28.0%, and even more preferably less than 25.0%.

The sum (mass sum) of the contents of the BaO component and the ZnO component is preferably 10.0% or more and 40.0% or less.

In particular, by setting the sum to 10.0% or more, the stability of the glass can be improved and the refractive index can be improved. Therefore, the mass sum (BaO + ZnO) is preferably more than 10.0%, more preferably more than 13.0%, still more preferably more than 15.0%, still more preferably more than 16.0%, and even more preferably more than 19.0%.

On the other hand, from the viewpoint of reducing devitrification due to excessive inclusion of these BaO components and ZnO components, the mass sum (BaO + ZnO) is preferably 40.0% or less, more preferably less than 35.0%, and even more preferably It is less than 30.0%, more preferably less than 25.0%, and even more preferably less than 23.0%.

The ratio (mass ratio) of the content of the TiO ₂ component to the content of the SiO ₂ component is preferably 1.00 or more.

In particular, by setting this mass ratio to 1.00 or more, the refractive index of glass can be increased. Therefore, the mass ratio TiO ₂ / SiO _{2 is} preferably 1.00 or more, more preferably more than 1.41, still more preferably more than 1.70, still more preferably more than 1.90, and even more preferably more than 2.00.

On the other hand, although the upper limit of the mass ratio may be infinite (that is, the content of the SiO ₂ component is 0), in particular, by setting the mass ratio to 3.00 or less, the stability of the glass can be improved. Therefore, the mass ratio TiO ₂ / SiO _{2 is} preferably 3.00 or less, more preferably 2.50 or less, and even more preferably 2.26 or less.

The ratio (mass ratio) of the sum of the contents of the TiO ₂ component, the ZnO component, and the BaO component to the content of the La ₂ O ₃ component is preferably 1.50 or less. This makes it possible to improve the refractive index without making the Abbe number of the glass too low. Therefore, the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O _{3 is} preferably 1.50 or less, more preferably 1.30 or less, still more preferably 1.08 or less, still more preferably less than 1.00, and still more preferably less than 0.950.

On the other hand, this ratio may be set to 0.50 or more. This can maintain the stability of the glass and increase the refractive index. Therefore, the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O _{3 is} preferably 0.50 or more, more preferably 0.60 or more, and still more preferably 0.70 or more.

The ratio (mass ratio) of the content of the BaO component to the content of the Ln ₂ O ₃ component (one or more selected from the group consisting of La, Gd, Y, and Yb in the formula Ln) is preferably 0.0400 or more and 0.5000 or less. the following.

In particular, by setting the ratio to 0.0400 or more, the stability of the glass can be improved, and a desired low Abbe number can be easily obtained. Therefore, the mass ratio BaO / Ln ₂ O _{3 is} preferably 0.0400 or more, more preferably 0.0600 or more, still more preferably more than 0.1000, still more preferably more than 0.1500, and still more preferably more than 0.2000.

On the other hand, by setting the ratio to 0.5000 or less, devitrification caused by excessively containing a BaO component can be reduced. Therefore, the mass ratio BaO / Ln ₂ O _{3 is} preferably 0.5000 or less, more preferably 0.4800 or less, still more preferably 0.4400 or less, still more preferably 0.3800 or less, and even more preferably 0.3433 or less.

The ratio (mass ratio) of the sum of the content of the SiO ₂ component and the BaO component to the content of the ZnO component is preferably 8.00 or less. Thereby, the stability of glass can be improved. Therefore, the mass ratio (SiO ₂ + BaO) / ZnO is preferably below 8.00, more preferably less than 7.20, still more preferably less than 6.50, still more preferably less than 5.50, still more preferably less than 5.30, and even more preferably less than 4.80, more preferably less than 4.00, and even more preferably less than 3.50.

The ratio (mass ratio) of the sum of the content of the TiO ₂ component and the La ₂ O ₃ component to the content of the BaO component is preferably 2.00 or more and 12.00 or less.

In particular, by setting the ratio to 2.00 or more, the refractive index of glass can be increased. Thus, the mass ratio of _{(TiO 2 + La 2 O 3} ) / BaO is preferably 2.00 or more, more preferably 2.50 or more, and more preferably 3.00 or more, and more preferably 3.50 or more, and more preferably 4.02 or more.

On the other hand, by setting the ratio to 12.00 or less, the stability of the glass can be improved and devitrification can be reduced. Therefore, the mass ratio (TiO ₂ + La ₂ O ₃ ) / BaO is preferably 12.00 or less, more preferably 10.0 or less, still more preferably 8.00 or less, still more preferably 7.50 or less, and even more preferably 7.26 or less.

Among the optical glass of the present invention, particularly preferred not only reduce the mass ratio of _{(SiO 2 + BaO) / ZnO} , will also mass ratio of _{(TiO 2 + La 2 O 3} ) / BaO is provided within the above range. This makes it possible to obtain a glass that is more stable, not only by increasing the refractive index.

Ln ₂ O ₃ component (one or more selected from the group consisting of La, Gd, Y, and Yb in the formula), the sum of the contents of the TiO ₂ component and the ZnO component relative to the B ₂ O ₃ component and SiO The ratio (mass ratio) of the sum of the contents of the _two components is preferably 2.00 or more and 5.00 or less.

In particular, by setting the ratio to 2.00 or more, the refractive index of glass can be increased. Therefore, the mass ratio (Ln ₂ O ₃ + TiO ₂ + ZnO) / (SiO ₂ + B ₂ O ₃ ) is preferably 2.00 or more, more preferably 2.35 or more, still more preferably 2.55 or more, and even more preferably 2.75 or more. , And more preferably 2.85 or more.

On the other hand, by setting the ratio to 5.00 or less, the stability of the glass can be improved. Accordingly, the mass ratio _{(Ln 2 O 3 + TiO 2} + ZnO) / (SiO 2 + B 2 O 3) is preferably 5.00 or less, more preferably 4.70 or less, and more preferably 4.40 or less, and more preferably 4.00 or less , And more preferably 3.50 or less.

The ratio (mass ratio) of the content of the TiO ₂ component to the sum of the contents of the SiO ₂ component, the B ₂ O ₃ component, the BaO component, and the WO ₃ component is preferably 0.15 or more and 1.00 or less.

In particular, by setting the ratio to 0.15 or more, the refractive index of glass can be increased. Therefore, the mass ratio TiO ₂ / (SiO ₂ + B ₂ O ₃ + BaO + WO ₃ ) is preferably 0.15 or more, more preferably 0.25 or more, still more preferably 0.35 or more, and still more preferably 0.39 or more.

On the other hand, by setting the ratio to 1.00 or less, the stability of the glass can be improved. Accordingly, the mass ratio of _{TiO 2 / (SiO 2 + B} 2 O 3 + BaO + WO 3) is preferably 1.00 or less, more preferably 0.80 or less, and more preferably 0.70 or less, and more preferably 0.60 or less.

The sum (mass) of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 5.0% or more and 25.0% or less.

In particular, by setting the sum to 5.0% or more, since the refractive index is increased, the Abbe number is lowered, and the stability of the glass is improved, it is possible to easily obtain a high refractive index and high dispersion optical glass. Therefore, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 5.0% or more, more preferably 7.0% or more, still more preferably more than 9.0%, still more preferably more than 11.0%, and even more preferably More than 14.0%.

On the other hand, by setting the sum to 25.0% or less, it is possible to reduce the coloration or devitrification of glass caused by excessively containing these components. Therefore, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 25.0% or less, more preferably less than 22.0%, still more preferably less than 19.0%, and even more preferably less than 17.0%.

Content of TiO ₂ component ₂ relative to component TiO, Nb ₂ O ₅ component and the total content of WO ₃ and the component ratio (mass ratio) is preferably 0.600 or more. Thereby, not only a high refractive index and a low Abbe number can be obtained, but also the material cost of the glass can be reduced. Therefore, the mass ratio TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 0.600 or more, more preferably 0.700 or more, still more preferably 0.702 or more, still more preferably 0.800 or more, and still more preferably 0.900. the above.

On the other hand, the upper limit of the mass ratio may be 1.000.

The ratio (mass ratio) of the content of the TiO ₂ component to the sum of the contents of the SiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 0.50 or more and 3.00 or less.

In particular, by setting this mass ratio to 1.00 or more, the refractive index of glass can be increased. Therefore, the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 0.50 or more, more preferably 1.00 or more, more preferably 1.30 or more, still more preferably 1.50 or more, and more preferably 1.81 or more. .

On the other hand, by setting the mass ratio to 3.00 or less, the stability of the glass can be improved. Therefore, the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 3.00 or less, more preferably 2.80 or less, still more preferably 2.50 or less, still more preferably 2.24 or less, and even more preferably 2.04. the following.

The ratio (mass ratio) of the sum of the content of the B ₂ O ₃ component and the ZnO component to the content of the SiO ₂ component is preferably 1.50 or more and 5.00 or less.

In particular, by setting the mass ratio to 1.50 or more, the refractive index of glass can be increased. Accordingly, the mass ratio _{(B 2 O 3 + ZnO)} / SiO 2 is preferably 1.50 or more, more preferably 1.80 or more, and more preferably 2.00 or more, and more preferably 2.37 or more.

On the other hand, although the upper limit of the mass ratio may be infinite (that is, the content of the SiO ₂ component is 0), the stability of the glass can be improved particularly by setting the mass ratio to 5.00 or less. Therefore, the mass ratio (B ₂ O ₃ + ZnO) / SiO _{2 is} preferably 5.00 or less, more preferably 4.50 or less, still more preferably 4.00 or less, still more preferably 3.50 or less, and more preferably 3.17 or less.

Here, the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) may be increased, and the mass ratio (B ₂ O ₃ + ZnO) / SiO _{2 may be} decreased. Thereby, a higher refractive index can be obtained.

In addition, the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) can also be reduced and the mass ratio (B ₂ O ₃ + ZnO) / SiO _{2 can be increased} . Thereby, a glass with higher stability can be obtained.

Therefore, by setting the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) and the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) within a predetermined range, the refractive index can be obtained. Higher and more stable glass.

The sum (mass sum) of the contents of Ta ₂ O ₅ component, Gd ₂ O ₃ component, and Nb ₂ O ₅ is preferably 10.0% or less. Thereby, since the costly material is reduced, the material cost of glass can be reduced. Therefore, the mass sum (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) is preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 5.0%, and even more preferably less than 2.0%. Still more preferably, it is less than 1.0%.

In addition, when the material cost is not too high, the quality and the content of the Ta ₂ O ₅ component and the Gd ₂ O ₃ component in the _three components can be suppressed to the aforementioned range.

The ratio (mass ratio) of the sum of the contents of the Ta ₂ O ₅ component, the Gd ₂ O ₃ component, and the Nb ₂ O ₅ component to the sum of the contents of the TiO ₂ component and the ZnO component is preferably 0.500 or less. With this, even among the components that increase the refractive index, since the components having a high material cost are reduced relative to the content of the TiO ₂ component and the ZnO component that are low in material cost, the material cost of glass can be reduced. Therefore, the mass ratio (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) / (TiO ₂ + ZnO) is preferably 0.500 or less, more preferably 0.400 or less, still more preferably 0.290 or less, and even more preferably 0.230 or less, more preferably 0.190 or less, and even more preferably less than 0.100.

The sum (mass sum) of the content of the CaO component and the SrO component is preferably 10.0% or less. This can suppress a decrease in the refractive index. Therefore, the mass sum (CaO + SrO) is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.5%.

The sum (mass sum) of the content of the RO component (one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn in the formula) is preferably 10.0% or more and 40.0% or less.

In particular, when the sum is 10.0% or more, the meltability of the glass raw material or the devitrification resistance of the glass can be improved. Therefore, the total content of the RO component is preferably 10.0% or more, more preferably more than 13.0%, still more preferably more than 15.0%, still more preferably more than 17.0%, and even more preferably more than 18.0%.

On the other hand, by setting the sum to 40.0% 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 the RO component is preferably 40.0% or less, more preferably less than 35.0%, still more preferably less than 30.0%, still more preferably less than 25.0%, and even more preferably less than 23.0%.

The sum (mass sum) of the content (mass sum) of the Rn ₂ O component (one or more selected from the group consisting of Li, Na, and K in the formula) is preferably 10.0% or less. This makes it possible to suppress a decrease in the refractive index of the glass and reduce devitrification. Therefore, the mass content of the Rn ₂ O component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%.

The sum (mass sum) of the content (mass) of the Ln ₂ O ₃ component (Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 25.0% or more and 54.0% or less.

In particular, when the sum of the masses is 25.0% or more, the refractive index of the glass can be increased, and thus a high-refractive-index glass can be easily obtained. Therefore, the quality and content of the content of the Ln ₂ O ₃ component is preferably 25.0% or more, more preferably 27.0% or more, still more preferably 30.0%, still more preferably 35.0%, or more preferably 36.0% or more, Even more preferably, it is greater than 37.0%.

On the other hand, by setting the mass sum to 54.0% or less, the liquidus temperature of the glass can be reduced, so that devitrification resistance can be improved. In addition, as a result, an increase in the Abbe number is suppressed and the material cost of the glass is suppressed. Therefore, the quality and content of the content of the Ln ₂ O ₃ component is preferably 54.0% or less, more preferably 52.0% or less, still more preferably less than 51.0%, still more preferably less than 49.0%, and even more preferably less than 45.0%. It is more preferably less than 43.0%, and even more preferably less than 40.0%.

<About ingredients that should not be contained>

Next, components which should not be contained in the optical glass of the present invention, and components which are poorly contained will be described.

As long as the characteristics of the glass of the present invention are not impaired, other components may be added as necessary. Among them, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo are contained in a small amount because they are each alone or in combination. In the case of each transition metal component, the glass is colored and has a property of generating absorption at a specific wavelength in the visible region. Therefore, it is particularly preferable that the glass is substantially not contained in optical glass using a 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, they are preferably substantially not contained, that is, they are not contained at all except for inevitable mixing.

In addition, in recent years, the components of Th, Cd, Tl, Os, Be, and Se have tended to be avoided as hazardous chemical substances in recent years. Not only the manufacturing steps of glass, but also the processing steps and the disposal after productization require environmental protection measures. Measures. Therefore, when environmental impact is taken into consideration, it is preferable that these components are not substantially contained.

[Production method]

The optical glass of this invention is produced as follows, for example. That is, the aforementioned raw materials are uniformly mixed so that each component falls within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible, or an alumina crucible, after coarse melting, and then added to the platinum crucible. , Platinum alloy crucible or iridium crucible, melting at a temperature range of 1100 ° C to 1400 ° C for 1 hour to 5 hours, stirring and homogenizing, and performing defoaming, etc., then the temperature is reduced to 1000 ° C to 1300 ° C to complete Stirred to remove streaks, cast into a mold, and slowly cooled.

<Physical properties>

The optical glass system of the present invention has a high refractive index and a high Abbe number (low dispersion).

In particular, the lower limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.85 or more, more preferably 1.87 or more, still more preferably 1.88 or more, more preferably 1.89 or more, and 1.90 or more. The upper limit of the refractive index is preferably 2.20 or less, more preferably less than 2.10, still more preferably less than 2.00, and even more preferably less than 1.95. In addition, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 25 or more, more preferably 27 or more, and still more preferably 30 or more. The upper limit of the Abbe number is preferably 35 or less, more preferably less than 34, and even more preferably less than 33.

Since the optical glass of the present invention has such a refractive index and an Abbe number, it is useful in optical design. In particular, not only high imaging characteristics can be expected, but also miniaturization of the optical system can be expected, and the degree of freedom in optical design can be extended.

Here, the optical glass of the present invention preferably has a relationship of refractive index (n _d ) and Abbe number (ν _d ) satisfying (−0.01 ν _d +2.15) ≦ n _d ≦ (−0.01 ν _d +2.25). Among glasses having a specific composition according to the present invention, a more stable glass can be obtained by satisfying this relationship with the refractive index (n _d ) and the Abbe number (ν _d ).

Therefore, in the optical glass of the present invention, the refractive index (n _d ) and Abbe number (ν _d ) preferably satisfy the relationship of n _d ≧ (-0.01 ν _d +2.15), and more preferably satisfy n _d ≧ ( -0.01 ν _d +2.17), and more preferably satisfies the relationship of n _d ≧ (-0.01 ν _d +2.19).

On the other hand, in the optical glass of the present invention, the refractive index (n _d ) and Abbe number (ν _d ) preferably satisfy the relationship of n _d ≦ (-0.01 ν _d +2.25), and more preferably satisfy n _d A relationship of ≦ (-0.01 ν _d +2.24), and more preferably a relationship of n _d ≦ (-0.01 ν _d +2.23).

The optical glass of the present invention preferably has a high transmittance of visible light, particularly light on a short wavelength side among visible light, and thereby has less coloration.

In particular, if the optical glass of the present invention is expressed by the transmittance of glass, the upper limit of the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample with a thickness of 10 mm is preferably 450 nm, more preferably 430 nm, and even more preferably 420nm.

In addition, in the optical glass of the present invention, the upper limit of the shortest wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% by a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, and even more preferably 370 nm.

With these, since the absorption end of the glass is in the vicinity of the ultraviolet region, the transparency of the glass with respect to visible light can be improved. Therefore, the optical glass is 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 5.00 or less. This reduces the quality of the optical element or the optical device using the optical element, which contributes to the weight reduction of the optical device. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.80, and even more preferably 4.70. The specific gravity of the optical glass of the present invention is about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more.

The specific gravity of the optical glass of the present invention is measured in accordance with the Japanese Optical Glass Industry Association standard JOGIS05-2015 "Method for Measuring Specific Gravity of Optical Glass".

The optical glass of the present invention preferably has high devitrification resistance, and more preferably has a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C, more preferably 1180 ° C, still more preferably 1150 ° C, and still more preferably 1100 ° C. Thereby, even if the melted glass flows out at a lower temperature, since the crystallization of the produced glass is reduced, the devitrification when the glass is formed from the molten state can be reduced, and the optical characteristics of the optical element using the glass can be reduced. Impact. In addition, since the glass can be formed even if the melting temperature of the glass is reduced, the energy consumed during the formation of the glass is suppressed, thereby reducing the manufacturing cost of the glass. On the other hand, although the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, most of the liquidus temperature of the glass obtained by the present invention is about 800 ° C or higher, specifically 850 ° C or higher, and more specifically It is said to be above 900 ° C. In addition, the "liquid phase temperature" in the present specification refers to the lowest temperature as follows: 30 cc of broken glass-like glass sample is added to a 50 ml platinum crucible, and the glass sample is completely melted at 1250 ° C, and the temperature is lowered to a predetermined temperature. On the other hand, it was maintained for 1 hour, taken out to the outside of the furnace, and immediately after cooling, the surface of the glass and the presence or absence of crystals in the glass were not observed. The predetermined temperature when the temperature is lowered here is a temperature measured every 10 ° C between 1200 ° C and 800 ° C.

[Glass molded body and optical element]

For example, a glass forming body can be produced from the produced optical glass by a method of grinding processing, a method of press molding such as reheating press forming, or precision press forming. That is, the optical glass can be machined by cutting and grinding to produce a glass shaped body, the preform made of optical glass can be reheated and press-molded, and then can be ground to produce a glass shaped body, or can be ground. The produced preform or a precision-molded preform formed by a known floating forming or the like is used to produce a glass formed body. The means for producing the glass formed 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 in various optical elements and optical designs, and among them, it is particularly preferably used for optical elements such as lenses and cymbals. Accordingly, since a glass shaped body having a large diameter can be formed, it is possible not only to increase the size of the optical element, but also to realize high-definition and high-accuracy imaging characteristics and projection characteristics when used in an optical device such as a camera or a projector.

[Example]

Examples (No.A1 to No.A29, No.B1 to No.B30) of the present invention have a composition, a refractive index (n _d ), an Abbe number (ν _d ), a liquidus temperature, and a display spectral transmittance of 5 The wavelengths (λ ₅ , λ ₇₀ ) and specific gravity of% and 70% are shown in Tables 1 to 8. Among them, Examples (No. A1 to No. A29) can also be used as examples of the first glass, and Examples (No. B1 to No. B30) can also be used as examples of the second glass.

In addition, the following examples are for the purpose of illustration and are not limited to these examples.

In the glass system of the examples, oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, and other high-purity raw materials commonly used in optical glasses, such as the raw materials corresponding to each component, are selected. After weighing and uniformly mixing the composition ratios of the respective examples and comparative examples shown in the table, the mixture was placed in a platinum crucible, and the electric furnace was used at a temperature range of 1100 ° C to 1400 ° C according to the ease of melting of the glass composition. After melting for 1 hour to 5 hours, after homogenizing with stirring to defoam, etc., the temperature is lowered to 1000 ° C. to 1300 ° C. After being homogenized with stirring, it is cast into a mold and slowly cooled to produce glass.

The refractive index (n _d ) and Abbe number (ν _d ) of the glass in the examples are measured values for the d-line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is the refractive index (nF) of the aforementioned d-line, the refractive index (nF) of the F-line (486.13nm) of the hydrogen lamp, and the refractive index (nC) of the C-line (656.27nm). The value is calculated from the equation of Abbe number (ν _d ) = [(n _d -1) / (nF-nC)]. Then, from the obtained refractive index (n _d ) and the Abbe number (ν _d ), the intercept b when the slope a is 0.01 in the relationship n _d = -a × ν _d + b is obtained. In addition, the glass used in this measurement is a glass processed in a slow-cooling furnace with a slow-cooling and cooling rate of -25 ° C / hr.

The liquidus temperature of the glass in the example is the lowest temperature determined as follows: 30 cc of broken glass-like glass sample was added to a 50 ml platinum crucible, the glass sample was completely melted at 1250 ° C, and the temperature was reduced to 1200 ° C Any temperature measured at 10 ° C was set to 800 ° C and maintained for 1 hour. After being taken out of the furnace and cooled, the surface of the glass and the presence or absence of crystals in the glass were immediately observed. No crystals were found.

The transmittance of the glass of the examples was measured according to the Japan Optical Glass Industry Association Standard JOGIS02-2003. In the present invention, the transmittance of glass is measured to determine the presence or absence of the coloration of the glass. Specifically, for a face-to-face parallel polished product having a thickness of 10 ± 0.1 mm, the spectral transmittance of 200 nm to 800 nm was measured according to JISZ8722, and λ ₅ (wavelength at 5% transmittance) and λ ₇₀ (wavelength at 70% transmittance) were determined. ).

The specific gravity of the glass of the examples was measured in accordance with the Japan Optical Glass Industry Association standard JOGIS05-2015 "Method for Measuring Specific Gravity of Optical Glass".

As shown in these tables, the optical glass-based refractive index (n _d ) of the examples of the present invention are all 1.85 or more, more specifically 1.89 or more, and the refractive index (n _d ) is 2.20 or less, and more specifically 1.91. In the following, it is within the required range.

In addition, the optical glass-based Abbe numbers (ν _d ) of the examples of the present invention are all 25 or more, more specifically 30 or more, and the Abbe numbers (ν _d ) are 35 or less, more specifically 33 or less, Within the required range.

In addition, the refractive index (n _d ) and Abbe number (ν _d ) of the optical glass system according to the embodiment of the present invention satisfy the relationship of (-0.01 ν _d +2.15) ≦ n _d ≦ (-0.01 ν _d +2.25), and more Specifically, it satisfies the relationship of (-0.02 ν _d +2.20) ≦ n _d ≦ (-0.02 ν _d +2.23). Next, the relationship between the refractive index (n _d ) and the Abbe number (ν _d ) of the glass of the example of the present application is shown in FIGS. 1 and 2.

Therefore, it was found that the optical glass according to the embodiment of the present invention can obtain the refractive index (n _d ) and Abbe when it contains at least a TiO ₂ component or a BaO component that is relatively inexpensive in the component that contributes to a high refractive index. Number (ν _d ) is a high-stability optical glass having a desired range.

In addition, the optical glass of the examples of the present invention does not devitrify, and the liquidus temperature is all 1200 ° C. or lower, more specifically, 1110 ° C. or lower, within the required range.

In addition, the specific gravity of the optical glass in the examples of the present invention is all 5.00 or less, and more specifically 4.70 or less, within the required range.

In addition, all the optical glass systems λ ₇₀ (wavelength at 70% transmittance) of the examples of the present invention are 450 nm or less, and more specifically 430 nm or less. The optical glass systems λ ₅ (wavelength at 5% transmittance) of the examples of the present invention are all 400 nm or less, and more specifically 370 nm or less. Therefore, it was found that the optical glass according to the embodiment of the present invention has high transmittance to visible light and is not easily colored.

Therefore, it was found that the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass system in the examples of the present invention are within a desired range, and it is possible to obtain inexpensively high stability, high transmittance for visible light, Optical glass with small specific gravity.

In the above, the present invention has been described in detail for the purpose of illustration. However, this embodiment is only for the purpose of illustration. Many changes can be made by those with ordinary knowledge in the technical field to which the present invention belongs without departing from the spirit and scope of the present invention.

Claims (20)

An optical glass containing, by mass%, a B ₂ O ₃ component of 6.0% to 30.0%; a La ₂ O ₃ component of 25.0% to 55.0%; a TiO ₂ component of 6.0% to 25.0%; and 4.0 BaO component of 2% or more and 27.0% or less; ZnO component content of 23.0% or less; has a refractive index (n _d ) of 1.85 or more, and an Abbe number (ν _d ) of 25 or more and 35 or less. The optical glass according to claim 1, which contains the following elements in terms of mass%: 0% to 13.0% SiO ₂ component; 0% to 10.0% Gd ₂ O ₃ component; 0% to 20.0% Y ₂ O ₃ composition; 0% to 10.0% Yb ₂ O ₃ composition; 0% to 15.0% Nb ₂ O ₅ composition; 0% to 20.0% WO ₃ composition; 0% to 15.0% ZrO ₂ composition; 0 % To 5.0% Ta ₂ O ₅ component; 0% to 5.0% MgO component; 0% to 10.0% CaO component; 0% to 10.0% SrO component; 0% to 5.0% Li ₂ O component; 0 % To 10.0% Na ₂ O component; 0% to 10.0% K ₂ O component; 0% to 10.0% P ₂ O ₅ component; 0% to 10.0% GeO ₂ component; 0% to 10.0% Al ₂ O ₃ component; 0% to 10.0% Ga ₂ O ₃ component; 0% to 10.0% Bi ₂ O ₃ component; 0% to 10.0% TeO ₂ component; 0% to 3.0% SnO ₂ component; and 0% to 1.0% of the Sb ₂ O ₃ component; the content of F as a fluoride substituted with one or two or more of the foregoing elements in part or all of the oxides is 0% to 10.0% by mass. The optical glass according to claim 1, wherein the mass sum (SiO ₂ + B ₂ O ₃ ) is 10.0% or more and 30.0% or less. The optical glass according to claim 1, wherein the mass sum (TiO ₂ + ZnO) is 10.0% or more and 45.0% or less.     The optical glass according to claim 1, wherein the mass sum (BaO + ZnO) is 10.0% or more and 40.0% or less.     The optical glass according to claim 1, wherein the mass ratio TiO ₂ / SiO ₂ is 1.00 or more. The optical glass according to claim 1, wherein the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O ₃ is 1.50 or less. The optical glass according to claim 1, wherein the mass ratio BaO / Ln ₂ O ₃ is 0.0400 to 0.5000, where Ln is one or more selected from the group consisting of La, Gd, Y, and Yb. The optical glass according to claim 1, wherein the mass ratio (SiO ₂ + BaO) / ZnO is 8.00 or less. The optical glass according to claim 1, wherein the mass ratio (Ln ₂ O ₃ + TiO ₂ + ZnO) / (SiO ₂ + B ₂ O ₃ ) is 2.00 or more and 5.00 or less, where Ln is represented by La, Gd, Y One or more selected from the group consisting of, and Yb. The optical glass according to claim 1, wherein the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 5.0% or more and 25.0% or less. The optical glass according to claim 1, wherein the mass ratio TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 0.600 or more and 1.000 or less. The optical glass according to claim 1, wherein the mass ratio TiO ₂ / (SiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 1.00 or more and 3.00 or less, and the mass ratio (B ₂ O ₃ + ZnO) / SiO ₂ is 1.50 or more Below 5.00. The optical glass according to claim 1, wherein the mass sum (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) is 10.0% or less. The optical glass according to claim 1, wherein the mass ratio (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) / (TiO ₂ + ZnO) is 0.500 or less.     The optical glass according to claim 1, wherein the mass sum (CaO + SrO) is 10.0% or less.     The optical glass according to claim 1, wherein in terms of mass%: the sum of the content of the RO component is 10.0% or more and 40.0% or less, where R is a group consisting of Mg, Ca, Sr, Ba, and Zn One or more selected; the sum of the contents of the Rn ₂ O component is 10.0% or less, where Rn is one or more selected from the group consisting of Li, Na, and K; the content of the Ln ₂ O ₃ component The sum is 25.0% to 54.0%, where Ln is one or more selected from the group consisting of La, Gd, Y, and Yb.     A preformed material composed of the optical glass according to any one of claims 1 to 17.         An optical element is composed of the optical glass according to any one of claims 1 to 17.         An optical device includes the optical element according to claim 19.