JP2019031441A - Optical glass and optical element - Google Patents

Abstract

To provide an optical glass and an optical element having refraction index (n) and Abbe number (ν) in a desired range and high in devitrification resistance at lower cost.SOLUTION: An optical glass contains, by mass%, BOcomponent of 10.0 to 40.0%, LaOcomponent of 25.0 to 55.0% and YOcomponent of over 0% and has mass ratio YO/(YO+GdO) of 0.500 or more and Abbe number (ν) of 39 or more. An optical element contains the optical glass as a base material.SELECTED DRAWING: None

Description

  The present invention relates to an optical glass 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 refractive index (n _d ) of 1.70 or more and an Abbe number of 39 or more and 60 or less (which can reduce the overall optical system weight and size). There is a great demand for high refractive index, low dispersion glass with ν _d ). As such a high refractive index and low dispersion glass, glass compositions represented by Patent Documents 1 to 4 are known.

JP 58-058669 A Japanese Patent Laid-Open No. 11-071129 JP 2008-001551 A JP 2011-093780 A

  As a method for producing an optical element from optical glass, for example, a gob or glass block formed from optical glass is ground and polished to obtain the shape of the optical element, or a gob or glass formed from optical glass. A method of grinding and polishing a glass molded product obtained by reheating and molding a block (reheat press molding), and molding a preform material obtained from a gob or glass block with an ultra-precision machined mold A method of obtaining the shape of an optical element by (precise mold press molding) is known. Any method is required to obtain a stable glass when a gob or glass block is formed from a molten glass raw material. Here, when the stability (devitrification resistance) with respect to devitrification of the glass which comprises the gob or glass block obtained falls and a crystal | crystallization generate | occur | produces inside glass, it can no longer obtain glass suitable as an optical element. Can not.

  In addition, in order to reduce the material cost of the optical glass, it is desirable that the raw material costs of the components constituting the optical glass be as low as possible. Moreover, in order to reduce the manufacturing cost of optical glass, it is desired that the raw material has high meltability and is melted at a lower temperature. However, it is difficult to say that the glasses described in Patent Documents 1 to 4 sufficiently satisfy these various requirements.

The present invention has been made in view of the above problems, and its object is to provide resistance to devitrification while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It is to obtain a glass having a high price at a lower cost.

The present inventors have found that in order to solve the above problems, the results of extensive _research, a combination of _Y 2 _{O 3} component B 2 _{O 3} component and _La 2 _{O 3} component, and the weight ratio _Y 2 O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) is set within a predetermined range, and the liquid phase temperature of the glass is lowered while the material cost of the glass is reduced, and the present invention is completed. It came. Specifically, the present invention provides the following.

(1) By mass%, B ₂ O ₃ component is contained in 10.0 to 40.0%, La ₂ O ₃ component is contained in 25.0 to 55.0%, and Y ₂ O ₃ component is contained in excess of 0%. An optical glass having a ratio Y ₂ O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) of 0.500 or more and an Abbe number (ν _d ) of 39 or more.

(2) The optical glass according to (1), wherein the content of the Gd ₂ O ₃ component is less than 10.0% by mass.

(3) Li ₂ O component in mass% 0 to 10.0%
ZnO component 0 to 25.0%
The optical glass according to (1) or (2).

(4) The content of SiO ₂ component is less than 30.0% (1) to (3) any description of the optical glass.

(5) Ta ₂ O ₅ component by mass% 0 to 18.0%
Yb ₂ O ₃ component 0 to 20.0%
The optical glass according to any one of (1) to (4).

(6) The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 25.0% to 75.0% (1 ) To (5).

(7) MgO component by mass% 0 to 20.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
BaO component 0 to 25.0%
The optical glass according to any one of (1) to (6).

  (8) The RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) has a mass sum of 25.0% or less, and any one of (1) to (7) The optical glass described in 1.

(9) TiO ₂ component by mass% 0 to 15.0%
Nb ₂ O ₅ component 0 to 20.0%
WO ₃ component 0-20.0%
The optical glass according to any one of (1) to (8).

(10) The optical glass according to any one of (1) to (9), wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is 30.0% or less.

(11) Na ₂ O component in mass% 0 to 10.0%
K ₂ O component 0 to 10.0%
Cs ₂ O component 0 to 10.0%
The optical glass according to any one of (1) to (10).

(12) The mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is 15.0% or less, from (1) to (11) Optical glass in any one.

(13)% by weight _P 2 _{O 5} component from 0 to 10.0%
GeO ₂ component 0-10.0%
ZrO ₂ component 0 to 15.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0-20.0%
SnO ₂ component 0-1.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) to (12).

(14) The optical glass according to any one of (1) to (13), which has a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 39 or more and 60 or less.

  (15) The optical glass according to any one of (1) to (14), which has a liquidus temperature of 1300 ° C. or lower.

  (16) The optical glass according to any one of (1) to (15), having a specific gravity of 5.50 or less.

  (17) An optical element having the optical glass according to any one of (1) to (16) as a base material.

  (18) An optical apparatus comprising the optical element according to (17).

According to the present invention, a glass having high devitrification resistance can be obtained at a lower cost while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges.

The optical glass of the present invention, from 10.0 to 40.0% of _B 2 _{O 3} component in wt.%, _La 2 _{O 3} component from 25.0 to 55.0%, and _Y 2 _{O 3} ingredients 0% and And the mass ratio Y ₂ O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) is 0.500 or more and has an Abbe number (ν _d ) of 39 or more. By combining the B ₂ O ₃ component and the La ₂ O ₃ component with the Y ₂ O ₃ component and making the mass ratio Y ₂ O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) within a predetermined range, Even if the amount of expensive components Gd ₂ O ₃ and Ta ₂ O ₅ used is small, stable glass can be easily obtained. At the same time, by using the B ₂ O ₃ component and the La ₂ O ₃ component as a base, the liquidus temperature tends to be low while having an Abbe number (ν _d ) of 39 or more. Therefore, an optical glass having high devitrification resistance and an optical element using the same can be obtained at a lower cost while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges.

  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. Unless otherwise specified in the present specification, the contents of the respective components are all expressed in mass% with respect to the total mass of the glass in terms of oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass component of the present invention are all decomposed and changed into an oxide when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

<About essential and optional components>
The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide.
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 dispersion of the glass can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 11.0%, and still more preferably 15.0%.
On the other hand, by making the content of the B ₂ O ₃ component 40.0% or less, a larger refractive index can be easily obtained, and deterioration of chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 40.0%, more preferably 38.0%, still more preferably 36.0%.
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 La ₂ O ₃ component is a component that increases the refractive index of the glass and decreases the dispersion (increases the Abbe number). In particular, a desired high refractive index can be obtained by containing 25.0% or more of the La ₂ O ₃ component. Accordingly, the content of the La ₂ O ₃ component is preferably 25.0%, more preferably 28.0%, even more preferably 31.0%, even more preferably 34.0%, and even more preferably 36.0%. More preferably, the lower limit is 39.0%, more preferably 42.0%, and still more preferably 45.0%.
On the other hand, the devitrification resistance of the glass can be increased by setting the content of the La ₂ O ₃ component to 55.0% or less. Accordingly, the content of the La ₂ O ₃ component is preferably 55.0%, more preferably 52.0%, and still more preferably 50.0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The Y ₂ O ₃ component is a component that can suppress the material cost of the glass and reduce the specific gravity while maintaining a high refractive index and a high Abbe number by containing more than 0%. Therefore, the content of the Y ₂ O ₃ component is preferably more than 0%, more preferably 2.0%, still more preferably 4.0%, still more preferably 4.5%, still more preferably 6.5%, More preferably, the lower limit is 8.0%.
On the other hand, by setting the content of the Y ₂ O ₃ component to 30.0% or less, a decrease in the refractive index of the glass can be suppressed and the devitrification resistance of the glass can be enhanced. Accordingly, the upper limit of the content of the Y ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, even more preferably 20.0%, and even more preferably 15.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

The Gd ₂ O ₃ component is an optional component that can increase the refractive index of the glass and increase the Abbe number when it exceeds 0%.
On the other hand, by reducing the particularly expensive Gd ₂ O ₃ component among rare earth elements to less than 10.0%, the specific gravity of the glass can be kept low, and the material cost of the glass can be kept down. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Therefore, the content of the Gd ₂ O ₃ component is preferably less than 10.0%, more preferably less than 8.0%, and still more preferably less than 5.0%.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The ratio of the content of the Y ₂ O ₃ component to the total amount of the Y ₂ O ₃ component and the Gd ₂ O ₃ component is preferably 0.500 or more. Thereby, the specific gravity of glass can be suppressed low and the material cost of glass can be suppressed while it is easy to obtain stable glass by including a plurality of rare earth components together with the La ₂ O ₃ component. Therefore, the mass ratio Y ₂ O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) is preferably 0.500, more preferably 0.600, and still more preferably 0.700.
The upper limit of this mass ratio may be 1.000.

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%.
On the other hand, by the content of Li 2 _O component to 10.0% or less, since the viscosity of the glass is increased, thereby reducing the striae of the glass. Moreover, this can make it difficult to lower the refractive index of the glass, increase the chemical durability of the glass, and improve the devitrification resistance. Therefore, the content of the Li ₂ O component is preferably 10.0%, more preferably 5.0% as an upper limit, still more preferably less than 3.0%, still more preferably less than 2.0%, still more preferably Less than 1.0%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ or the like can be used as a raw material.

The ZnO component is an optional component that can lower the glass transition point and increase chemical durability when it is contained in excess of 0%. Therefore, the content of the ZnO component is preferably more than 0%, more preferably 1.0%, and further preferably 1.5%.
On the other hand, by setting the content of the ZnO component to 25.0% or less, a decrease in the refractive index of glass and a decrease in devitrification resistance can be suppressed. 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 ZnO component is preferably 25.0%, more preferably 20.0%, further preferably 15.0%, further preferably 10.0%, and more preferably 5.0%. Less than.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The SiO ₂ component is an optional component that, when contained over 0%, can increase the viscosity of the molten glass, reduce the coloration of the glass, and increase the devitrification resistance. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably 1.0%, still more preferably 1.3%, and still more preferably 2.0%.
On the other hand, when the content of the SiO ₂ component is 30.0% or less, an increase in the glass transition point can be suppressed and a decrease in the refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably 30.0%, more preferably 20.0%, still more preferably 15.0%, further preferably less than 10.0%, still more preferably 8. Less than 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 Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass, increase the devitrification resistance, and increase the viscosity of the molten glass when it contains more than 0%.
On the other hand, by making the content of the expensive Ta ₂ O ₅ component 18.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. Moreover, since the melting temperature of a raw material becomes low by this and the energy required for melting of a raw material is reduced, the manufacturing cost of optical glass can also be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 18.0%, more preferably 16.0%, still more preferably 13.0%, and still more preferably 9.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component that can increase the refractive index of the glass and reduce the dispersion when it exceeds 0%.
On the other hand, since the material cost of glass is reduced by making the content of the Yb ₂ O ₃ component 20.0% or less, a cheaper optical glass can be produced. This also increases the devitrification resistance of the glass. Therefore, the content of the Yb ₂ O ₃ component is preferably 20.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably. Less than 1.0%, most preferably not contained.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

The sum (mass sum) of contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 25.0% to 75.0% Is preferred.
In particular, when the sum is 25.0% or more, the dispersion of the glass can be reduced. Therefore, the mass sum of the Ln ₂ O ₃ component is preferably 25.0%, more preferably 30.0%, even more preferably 36.0%, still more preferably 41.0%, and even more preferably 44.0%. More preferably, 47.0%, more preferably 50.0%, and still more preferably 53.0%.
On the other hand, by setting the sum to 75.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. Accordingly, the upper limit of the mass sum of the Ln ₂ O ₃ component is preferably 75.0%, more preferably 70.0%, still more preferably 65.0%, and even more preferably 61.0%.

The ratio of the content of La ₂ O ₃ component to the total amount of La ₂ O ₃ component, Y ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component is preferably 0.600 or more and 0.900 or less. . By setting this ratio within the range of 0.600 or more and 0.900 or less, devitrification resistance can be improved even when the total amount of the Ln ₂ O ₃ component is large. Therefore, the mass ratio La ₂ O ₃ / (La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is preferably 0.600, more preferably 0.650, still more preferably 0.700, Preferably, 0.750 is set as the lower limit. On the other hand, the upper limit of this mass ratio is preferably 0.900, more preferably 0.880, and still more preferably 0.850.

The MgO component, CaO component, SrO component, and BaO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when the content exceeds 0%.
On the other hand, the content of each of the MgO component, the CaO component and the SrO component is made 20.0% or less and / or the content of the BaO component is made 25.0% or less. Reduction of refractive index and devitrification resistance due to excessive inclusion can be suppressed. Therefore, the content of each of the MgO component, the CaO component and the SrO component is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, still more preferably 7.0%, still more preferably Is 4.5%, more preferably 3.0%. The content of the BaO component is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%. To do.
MgO component, CaO component, SrO component and BaO component are MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ etc. as raw materials. Can be used.

  The total content (mass sum) of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 25.0% or less. Thereby, the fall of the refractive index of glass and the fall of devitrification resistance by containing excessive RO component can be suppressed. Therefore, the mass sum of the RO component is preferably 25.0%, more preferably 15.0%, more preferably less than 10.0%, still more preferably 8.5% or less, and still more preferably 5. 0% or less.

The TiO ₂ component is an optional component that can increase the refractive index of the glass, adjust the Abbe number to a low level, and increase the resistance to devitrification when it contains more than 0%.
On the other hand, by making the content of TiO ₂ 15.0% or less, 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 upper limit of the content of the TiO ₂ component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, and still more preferably 3.0%.
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 of the glass and increase the devitrification resistance when it exceeds 0%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 20.0% or less, it is possible to reduce the devitrification resistance of the glass due to the excessive content of the Nb ₂ O ₅ component and the transmittance of visible light. Can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 8.0%.
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 increase the devitrification resistance of the glass while reducing the coloring of the glass due to other high refractive index components when it contains more than 0%. Further, WO ₃ components, it is also a component can be lowered glass transition temperature.
On the other hand, by making the content of the WO ₃ component 20.0% or less, the coloring of the glass by the WO ₃ component can be reduced and the visible light transmittance can be increased. Accordingly, the upper limit of the content of the WO ₃ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and still more preferably 3.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

Here, the sum (mass sum) of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 30.0% or less. Thereby, since the fall of Abbe number is suppressed, it can be easy to obtain a desired Abbe number. Further, coloring due to excessive inclusion of these components can be reduced, and devitrification resistance can be enhanced. Accordingly, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 30.0%, more preferably 20.0%, still more preferably 15.0%, still more preferably 11.0%, still more preferably The upper limit is 8.0%.

Na ₂ O component, K ₂ O component, and Cs ₂ O component are optional components that can improve the meltability of glass, increase the devitrification resistance of glass, and lower the glass transition point when contained in excess of 0%. It is.
On the other hand, by making each content of the Na ₂ O component, the K ₂ O component and the Cs ₂ O component 10.0% or less, the refractive index of the glass is hardly lowered and the devitrification resistance is reduced. Enhanced. Therefore, the content of each of the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
Na ₂ O component, _{K 2} O component and Cs ₂ O component, NaNO ₃ as a raw _{material, NaF, Na 2 SiF 6,} K 2 CO 3, KNO 3, KF, KHF 2, K 2 SiF 6, Cs 2 CO 3 , CsNO ₃ or the like can be used.

The total amount of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is preferably 15.0% or less. Thereby, the fall of the refractive index of glass can be suppressed and devitrification resistance can be improved. Accordingly, the upper limit of the mass sum of the Rn ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances devitrification resistance of the glass. In particular, by making the content of the P ₂ O ₅ component 10.0% 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 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ 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 improve the devitrification resistance when it contains more than 0%. However, since the raw material price of GeO ₂ is high, the material cost increases when the amount of GeO ₂ is large, thereby reducing the cost reduction effect by reducing the Ta ₂ O ₅ component and the like. Accordingly, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 1.0%, and most preferably not contained.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

When the ZrO ₂ component is contained in an amount of more than 0%, it can contribute to a higher refractive index and a lower dispersion of the glass, and the devitrification resistance of the glass can be improved. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and even more preferably 5.0%.
On the other hand, by making the ZrO ₂ component 15.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to the excessive inclusion of the ZrO ₂ component. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 15.0%, more preferably 10.0%, and still more preferably 7.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can increase the chemical durability of the glass and increase the devitrification resistance of the glass when contained in excess of 0%.
On the other hand, by making each content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 10.0% or less, a decrease in the devitrification resistance of the glass due to the excessive content thereof can be suppressed. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like can be used as a raw material.

A Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, 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%, more preferably 5.0%, and still more preferably 3.0%.
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%.
However, TeO ₂ has a problem that it can be alloyed with platinum when a glass raw material is melted in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Accordingly, the content of the TeO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably not contained.
TeO ₂ component can use TeO ₂ or the like as a raw material.

When the SnO ₂ component is contained in an amount of more than 0%, the SnO ₂ component is an optional component that can be refined by reducing the oxidation of the molten glass and can increase the visible light transmittance of the glass.
On the other hand, by setting the content of the SnO ₂ component to 1.0% or less, it is possible to reduce the coloring of the glass due to the reduction of the molten glass and the devitrification of the glass. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 1.0%, more preferably 0.7%, and still more preferably 0.5%.
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. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.7%, and still more preferably 0.5%.
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.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer or a combination thereof.

<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. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component from 25.0 to 60.0 mol%,
La ₂ O ₃ component 10.0 to 30.0 mol%, and _Y 2 _{O 3} component 0% and 15.0 mol%,
Gd ₂ O ₃ component 0-5.0 mol%,
Li ₂ O component 0 to 30.0 mol%,
ZnO component 0 to 30.0 mol%,
SiO ₂ component 0 to 45.0 mol%,
Ta ₂ O ₅ component 0-5.0 mol%,
Yb ₂ O ₃ component 0 to 5.0 mol%,
MgO component 0 to 25.0 mol%,
CaO component 0 to 25.0 mol%,
SrO component 0 to 15.0 mol%,
BaO component 0 to 20.0 mol%,
TiO ₂ component 0 to 20.0 mol%,
Nb ₂ O ₅ component 0 to 10.0 mol%,
WO ₃ component 0-10.0 mol%,
Na ₂ O component 0 to 20.0 mol%,
K ₂ O component 0 to 10.0 mol%,
Cs ₂ O component 0-5.0 mol%,
P ₂ O ₅ component 0 to 10.0 mol%,
GeO ₂ component 0 to 10.0 mol%,
ZrO ₂ component 0 to 15.0 mol%,
Al ₂ O ₃ component 0 to 10.0 mol%,
Ga ₂ O ₃ component 0-5.0 mol%,
Bi ₂ O ₃ component 0-5.0 mol%,
TeO ₂ component 0 to 15.0 mol%,
SnO ₂ component 0 to 1.0 mol%, or Sb ₂ O ₃ component 0 to 0.5 mol%

[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, the prepared mixture is put into a platinum crucible, and 1100-1500 ° C. in an electric furnace depending on the difficulty of melting the glass composition. It is produced by melting in the temperature range of 2 to 5 hours, stirring and homogenizing, lowering to an appropriate temperature, casting into a mold, and slow cooling.

[Physical properties]
The optical glass of the present invention preferably has a high refractive index and a high Abbe number (low dispersion). In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.73, and still more preferably 1.75. The upper limit of this refractive index is preferably 2.20, more preferably 2.10, and even more preferably 2.00. In addition, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 39, more preferably 40, still more preferably 42 as a lower limit, preferably 60, more preferably 58, and still more preferably 55. .
In addition, the Abbe number (ν _d ) of the optical glass of the present invention preferably satisfies the relationship (ν _d ) ≧ (−125 × n _d +260) with respect to the refractive index (n _d ), _d ) ≧ (−125 × n _d +265) is more preferable, (ν _d ) ≧ (−125 × n _d +267) is more preferable, and (ν _d ) ≧ (−125). It is more preferable to satisfy the relationship of × n _d +270).
By having such a high refractive index, a large amount of light can be obtained even if the optical element is thinned. In addition, by having such low dispersion, even with a single lens, focus shift (chromatic aberration) due to the wavelength of light is reduced. In addition, by having such low dispersion, for example, when combined with an optical element having high dispersion (low Abbe number), high imaging characteristics and the like can be achieved.
Therefore, the optical glass of the present invention is useful in optical design, and the optical system can be miniaturized and the degree of freedom in optical design can be expanded while achieving particularly high imaging characteristics.

  The optical glass of the present invention preferably has high devitrification resistance, more specifically, a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1300 ° C., more preferably 1280 ° C., and further preferably 1250 ° C. As a result, even if the molten glass flows out at a lower temperature, crystallization of the produced glass is reduced, and thus devitrification when the glass is formed from a molten state can be reduced, and an optical element using glass The influence on the optical characteristics can be reduced. Moreover, since glass can be shape | molded even if the melting temperature of glass is lowered | hung, the manufacturing cost of glass can be reduced by suppressing the energy consumed at the time of shaping | molding glass. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is preferably 500 ° C, more preferably 600 ° C, and even more preferably 700 ° C. Also good. In this specification, “liquid phase temperature” refers to a 30 ml cullet-shaped glass sample placed in a platinum crucible in a 50 ml capacity platinum crucible, completely melted at 1350 ° C., and cooled to a predetermined temperature. The glass surface and the presence or absence of crystals in the glass are observed immediately after taking out of the furnace and cooling, and indicates the lowest temperature at which no crystals are observed. The predetermined temperature when the temperature is lowered is a temperature in increments of 10 ° C. up to 1300 ° C.

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 ₈₀ ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 500 nm, more preferably 450 nm, and still more preferably 420 nm. The upper limit.
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 360 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 [g / cm ³ ] 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 5.20, 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”.

[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. 9) and Comparative Example (No. A) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), liquidus temperature, and spectroscopic of these glasses Tables 1 and 2 show the results of the wavelengths (λ ₅ and λ ₈₀ ) at which the transmittance is 5% and 80% and the specific gravity. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of the examples and comparative examples of the present invention are ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to the raw materials of the respective components. The high-purity raw materials used in the above are selected, weighed so as to have the composition ratios of the respective examples shown in the table and mixed uniformly, and then put into a platinum crucible, depending on the melting difficulty of the glass composition. After melting in a temperature range of 1100 to 1500 ° C. for 2 to 5 hours in an electric furnace, the mixture was homogenized with stirring, cast into a mold or the like, and slowly cooled to produce glass.

  Here, the refractive index and the Abbe number of the glass of an Example and a comparative example were measured based on Japan Optical Glass Industry Association standard JOGIS01-2003. Here, the refractive index and the Abbe number were determined by measuring the glass obtained at a slow cooling rate of -25 ° C / hr.

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

  The liquid phase temperature of the glass of the examples and comparative examples is as follows. A 30 cc cullet-shaped glass sample was put in a platinum crucible in a platinum crucible having a capacity of 50 ml and completely melted at 1350 ° C. 1300 ° C. to 1160 ° C. The temperature is lowered to any temperature set in increments of 10 ° C. and held for 12 hours. After taking out of the furnace and cooling, the glass surface and the presence or absence of crystals in the glass are observed immediately, and the lowest crystal is not observed. The temperature was determined.

  Moreover, 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 the table, the optical glass of the example of the present invention has a mass ratio Y ₂ O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) of 0.500 or more, so that Gd ₂ O ₃ and Since the usage amount of Ta ₂ O ₅ or the like is reduced, it can be obtained at a lower cost. On the other hand, the glass of the comparative example (No. A) has a high material cost as is apparent from the fact that it contains a large amount of molar sum Gd ₂ O ₃ and Ta ₂ O ₅ .

  All of the optical glasses of the examples of the present invention had a liquidus temperature of 1300 ° C. or lower, more specifically 1230 ° C. or lower, and were within a desired range. For this reason, it became clear that the optical glass of the Example of this invention has low liquidus temperature, and high devitrification resistance.

The optical glasses of the examples of the present invention all had λ ₈₀ (wavelength at 80% transmittance) of 500 nm or less, more specifically 440 nm or less. In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength at 5% transmittance) was 400 nm or less, more specifically, 328 nm or less.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.70 or more, with more detail is 1.73 or more, the refractive index is 2.20 or less, more detail Was 1.90 or less and was within the desired range.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 35 or more, more specifically 40 or more, and this Abbe number is 60 or less, more specifically 55 or less. It was within the desired range.

  The optical glasses of the examples of the present invention all had a specific gravity of 5.50 or less, more specifically 5.30 or less, and were within a desired range.

Therefore, the optical glass of the example of the present invention is desired to have a refractive index and an Abbe number while the amount of expensive components such as Gd ₂ O ₃ and Ta ₂ O ₅ is reduced compared to the glass of the comparative example. The devitrification resistance was high, the coloring was small, and the specific gravity was small.

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

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

Claims (18)

It contains 10.0 to 40.0% of B ₂ O ₃ component, 25.0 to 55.0% of La ₂ O ₃ component, and more than 0% of Y ₂ O ₃ component in mass%, and the mass ratio Y ₂ An optical glass having an O ₃ / (Y ₂ O ₃ + Gd ₂ O ₃ ) of 0.500 or more and an Abbe number (ν _d ) of 39 or more. The optical glass according to claim 1, wherein the content of the Gd ₂ O ₃ component is less than 10.0% by mass. Li ₂ O component in mass% 0 to 10.0%
ZnO component 0 to 25.0%
The optical glass according to claim 1 or 2. The optical glass according to any one of claims 1 to 3, wherein the content of the SiO ₂ component is 30.0% or less. Ta ₂ O ₅ component by mass% 0 to 18.0%
Yb ₂ O ₃ component 0 to 20.0%
The optical glass according to any one of claims 1 to 4. The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is 25.0% or more and 75.0% or less. The optical glass according to any one of the above. MgO component in mass% 0 to 20.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
BaO component 0 to 25.0%
The optical glass according to any one of claims 1 to 6.   8. The optical glass according to claim 1, wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) has a mass sum of 25.0% or less. . TiO ₂ component in mass% 0 to 15.0%
Nb ₂ O ₅ component 0 to 20.0%
WO ₃ component 0-20.0%
The optical glass according to any one of claims 1 to 8. The optical glass according to any one of claims 1 to 9, wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is 30.0% or less. Na ₂ O component in mass% 0 to 10.0%
K ₂ O component 0 to 10.0%
Cs ₂ O component 0 to 10.0%
The optical glass according to any one of claims 1 to 10. The mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is 15.0% or less. Optical glass. _P 2 _{O 5} component from 0 to 10.0% by mass%
GeO ₂ component 0-10.0%
ZrO ₂ component 0 to 15.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component from 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0-20.0%
SnO ₂ component 0-1.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of claims 1 to 12. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 39 or more and 60 or less.   The optical glass according to claim 1, which has a liquidus temperature of 1300 ° C. or lower.   The optical glass according to claim 1, which has a specific gravity of 5.50 or less.   The optical element which uses the optical glass in any one of Claim 1 to 16 as a base material.   An optical apparatus comprising the optical element according to claim 17.