JP2013209232A - Optical glass and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass having higher devitrification resistance regardless of its refractive index (n) and Abbe number (ν) being within the desired range, and an optical element using the same.SOLUTION: An optical glass contains, in mass%, 1.0-30.0% of a BOcomponent and 10.0-60.0% of an LaOcomponent, and has a content of an SiOcomponent of ≤20.0% and an Abbe number (ν) satisfying the relationship of (ν)≥(-100×n+227.0) between its Abbe number (ν) and refractive index (n). An optical element uses the optical glass as a base material.

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 1.75 or more and an Abbe number of 35 or more and 50 or less (which can reduce the weight and size of the entire optical system). 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 3 are known.

JP 2004-099428 A JP 2006-240889 A JP 2009-298646 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.

  Further, in order to obtain a large amount of light refraction even if the optical element is made thin, it is desirable that the refractive index of the optical glass be higher in the above range. However, in the glasses described in Patent Documents 1 to 3, the refractive index is insufficient, and if the refractive index is increased while maintaining the desired Abbe number range, the devitrification resistance of the glass decreases. To do.

The present invention has been made in view of the above-described problems, and the object of the present invention is to provide more resistance to loss even though the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. The object is to obtain an optical glass with high permeability.

In order to solve the above-mentioned problems, the present inventors have conducted extensive test studies, and as a result, the SiO ₂ content is reduced and a composition system based on the B ₂ O ₃ component and the La ₂ O ₃ component is obtained. Thus, the inventors have found that the liquidus temperature can be lowered while suppressing a decrease in the refractive index, and the present invention has been completed. Specifically, the present invention provides the following.

(1) 1.0 to 30.0% of B ₂ O ₃ component and 10.0 to 60.0% of La ₂ O ₃ component are contained by mass%, and the content of SiO ₂ component is 20.0% or less. And the Abbe number (ν _d ) satisfies the relationship of (ν _d ) ≧ (−100 × n _d +227.0) with the refractive index (n _d ).

(2) Gd ₂ O ₃ component by mass% 0 to 40.0%
Y ₂ O ₃ component 0 to 30.0%
Yb ₂ O ₃ component 0 to 20.0%
The optical glass according to (1).

(3) 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, and Lu) is 30.0% or more and 70.0% or less. The optical glass according to (1) or (2).

(4) The optical glass according to any one of (1) to (3), wherein the content of the Ta ₂ O ₅ component is more than 0% and 30.0% or less.

(5) The sum of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) and the Ta ₂ O ₅ component is 45.0% The optical glass according to any one of (1) to (4), which is 80.0% or less.

(6) The optical glass according to any one of (1) to (5), wherein the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 1.0% or more and 30.0% or less.

(7) The optical glass according to any one of the weight ratios _SiO 2 _/ B 2 _{O 3} is 0.70 or less (1) (6).

(8) mass ratio _{(Ln 2 O 3 + Ta 2} O 5) / optical glass according to any one of _{(SiO 2 + B 2 O 3} ) is 2.00 or more (1) (7).

(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) By mass%, Li ₂ O component 0 to 10.0%
ZnO component 0 to 25.0%
The optical glass according to any one of (1) to (10).

(12) 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 (11).

(13) 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 (12) Optical glass in any one.

(14) MgO component in mass% 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 25.0%
The optical glass according to any one of (1) to (13).

  (15) 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 (14) The optical glass described in 1.

(16)% 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 (15).

(17) The optical glass according to any one of (1) to (16), which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 35 or more and 50 or less.

  (18) The optical glass according to any one of (1) to (17), which has a liquidus temperature of 1300 ° C. or lower.

  (19) An optical element having the optical glass according to any one of (1) to (18) as a base material.

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

According to the present invention, an optical glass having higher devitrification resistance can be obtained while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges.

The optical glass of the present invention contains 1.0 to 30.0% of a B ₂ O ₃ component and 10.0 to 60.0% of a La ₂ O ₃ component by mass%, and the content of SiO ₂ component is 20%. The Abbe number (ν _d ) satisfies the relationship of (ν _d ) ≧ (−100 × n _d +227.0) with the refractive index (n _d ). By reducing the SiO ₂ content and making the composition system based on the B ₂ O ₃ component and the La ₂ O ₃ component, the rise of the glass transition point (Tg) can be suppressed, thereby reducing the introduction of low melting point components. Therefore, the liquidus temperature can be lowered while suppressing a decrease in the refractive index. At the same time, by using a B ₂ O ₃ component and a La ₂ O ₃ component as a base, while having a high refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 35 or more, liquid The phase temperature tends to be lower. Therefore, an optical glass having high devitrification resistance and an optical element using the same can be obtained while the refractive index (n _d ) and the 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 1.0% 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 1.0%, more preferably 5.0%, still more preferably 8.3%, and still more preferably 10.0%.
On the other hand, by making the content of the B ₂ O ₃ component 30.0% 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 30.0%, more preferably 25.0%, even more preferably 20.0%, still more preferably 19.0%, still more preferably 17.5%. Is the upper limit.
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 10.0% or more of the La ₂ O ₃ component. Accordingly, the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 15.0%, still more preferably 20.0%, still more preferably 25.0%, and even more preferably 30.0%. Is the lower limit.
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 60.0% or less. Accordingly, the content of the La ₂ O ₃ component is preferably 60.0%, more preferably 58.0%, still more preferably 55.0%, and even 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 SiO ₂ component is an optional component that can increase the viscosity of the molten glass and reduce the coloration of the glass when it contains more than 0%.
On the other hand, by setting the content of the SiO ₂ component to 20.0% or less, devitrification resistance can be enhanced while suppressing a decrease in refractive index. Moreover, this can also suppress an increase in the glass transition point. Therefore, the upper limit of the content of the SiO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 6.0%, still more preferably 5.0%, and even more preferably 4.3%. And more preferably less than 3.0%.
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 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, the glass material cost can be reduced by reducing the expensive Gd ₂ O ₃ component among the rare earth elements to 40.0% or less. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Accordingly, the content of the Gd ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, even more preferably 20.0%, and even more preferably 17.0%.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional 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 when it contains more than 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. Therefore, the content of the Y ₂ O ₃ component is preferably 30.0%, more preferably 20.0%, and still more preferably 10.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

The Yb 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 making the content of _Yb 2 _{O 3} component below 20.0%, thereby reducing the material cost of the glass. This also increases the devitrification resistance of the glass. Therefore, the content of the Yb ₂ O ₃ component is preferably 20.0%, more preferably 10.0%, and still more preferably 5.0%.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

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 30.0% to 70.0% Is preferred.
In particular, the dispersion of the glass can be reduced by setting this sum to 30.0% or more. Accordingly, the lower limit of the mass sum of the Ln ₂ O ₃ component is preferably 30.0%, more preferably 35.0%, even more preferably 40.0%, and even more preferably 42.5%.
On the other hand, by setting the sum to 70.0% 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 70.0%, more preferably 65.0%, still more preferably 60.0%, and even more preferably 56.0%.

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%. Therefore, the content of the Ta ₂ O ₅ component is preferably more than 0%, more preferably more than 5.0%, still more preferably more than 10.0%, still more preferably more than 12.0%, and still more preferably 13. It may be greater than 0%, more preferably greater than 13.5%, and even more preferably greater than 16.0%.
On the other hand, the material cost of glass can be reduced by making expensive Ta ₂ O ₅ component 30.0% or less. Therefore, the content of the Ta ₂ O ₅ component is preferably 30.0%, more preferably 28.0%, and still more preferably 25.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

In the optical glass of the present invention, the sum (mass sum) of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) and the Ta ₂ O ₅ component. ) Is preferably 45.0% or more and 80.0% or less.
In particular, the refractive index of glass can be raised more by making this sum 45.0% or more. Therefore, the mass sum (Ln ₂ O ₃ + Ta ₂ O ₅ ) is preferably 45.0%, more preferably 50.0%, still more preferably 53.0%, still more preferably 57.0%, still more preferably The lower limit is 61.0%.
On the other hand, devitrification due to excessive inclusion of these components can be reduced by making this sum 80.0% or less. Accordingly, the upper limit of the mass sum (Ln ₂ O ₃ + Ta ₂ O ₅ ) is preferably 80.0%, more preferably 75.0%, and even more preferably 73.0%.

In the optical glass of the present invention, the sum (mass sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 1.0% or more and 30.0% or less.
In particular, by making this sum 1.0% or more, it is possible to suppress a decrease in devitrification resistance due to the lack of the B ₂ O ₃ component or the SiO ₂ component. Accordingly, the lower limit of the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 1.0%, more preferably 5.0%, still more preferably 10.0%, and even more preferably 13.0%.
On the other hand, by making this sum 30.0% or less, a decrease in the refractive index due to excessive inclusion of these components can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0% as an upper limit, more preferably less than 23.0%, still more preferably less than 20.0%, still more preferably less than 19.0%. And

Moreover, the ratio (mass ratio) of the content of the SiO ₂ component to the content of the B ₂ O ₃ component is preferably 0.70 or less.
In particular, by setting this ratio to 0.70 or less, the glass tends to soften even by heating at a lower temperature while maintaining the desired optical constant, thereby improving the formability during press molding. Can do. Therefore, the mass ratio SiO ₂ / B ₂ O ₃ is preferably 0.70, more preferably 0.55, still more preferably 0.46, still more preferably 0.31, and even more preferably 0.25. .

Further, Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) and Ta _{2 with} respect to the sum of the contents of B ₂ O ₃ component and SiO ₂ component The sum ratio (mass ratio) of the content of the O ₅ component is preferably 2.00 or more.
In particular, by setting this ratio to 2.00 or more, the refractive index can be increased while maintaining high devitrification resistance. Therefore, the mass ratio (Ln ₂ O ₃ + Ta ₂ O ₅ ) / (SiO ₂ + B ₂ O ₃ ) is preferably 2.00, more preferably 3.00, still more preferably 3.50, and even more preferably 3. 837 is set as the lower limit.
On the other hand, the upper limit of this ratio is preferably from the viewpoint of suppressing excessive depletion of Ln ₂ O ₃ component and Ta ₂ O ₅ component and devitrification resistance due to lack of B ₂ O ₃ component and SiO ₂ component. May be 7.00, more preferably 6.00, and even more preferably 5.50.

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 making the content of the Nb ₂ O ₅ component 20.0% or less, the devitrification resistance of the glass is decreased due to excessive content of the Nb ₂ O ₅ component, the Abbe number is decreased, and visible light is reduced. Decrease in transmittance can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 2.5%. The Nb ₂ O ₅ component may not be contained from the viewpoint of further increasing the Abbe number.
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%. Accordingly, the content of the WO ₃ component is preferably more than 0%, more preferably 0.5%, still more preferably 0.9%, and even more preferably 1.0%.
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 8.0%, and even more preferably 4.0%.
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. Therefore, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 30.0%, more preferably 25.0%, still more preferably 19.0%, still more preferably 14.0%, and even more preferably. The upper limit is 11.0%, more preferably 7.0%, and even more preferably 4.0%.
The mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably more than 0%, more preferably 0.5%, and still more preferably from the viewpoint of increasing the refractive index of the glass and increasing the devitrification resistance. It is good also considering 1.0% as a minimum.

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. Further, this makes it difficult to lower the refractive index of the glass, can improve the chemical durability of the glass, and can improve the devitrification resistance. Therefore, the content of the Li ₂ O component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.5%, still more preferably 1.0%. The upper limit is set, more preferably less than 0.3%.
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 more than 1.0%, and even more preferably more than 5.0%.
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%, still more preferably 15.0%, and even more preferably less than 14.5%.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

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. Here, 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, it is difficult to lower the refractive index of the glass, and the devitrification resistance is improved. 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 are NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ , Cs ₂ CO ₃ as raw materials. , 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. Therefore, the upper limit of the mass sum of the Rn ₂ O component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.

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 set to 10.0% or less, and / or the content of the BaO component is set to 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, CaO component and SrO component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%. The content of the BaO component is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 5.0%.
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. Accordingly, the upper limit of the mass sum of the RO component is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 5.0%.

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 GeO ₂ has a high raw material price, a large amount of GeO ₂ increases the material cost. Therefore, the content of the GeO ₂ component is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%.
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%, and even more preferably 3.0%.
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 the content exceeds 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 not described above can be added as necessary within a 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 2.0 to 60.0 mol%, and _La 2 _{O 3} component from 5.0 to 30.0 mol%,
And SiO ₂ component 0 to 60.0 mol%,
Gd ₂ O ₃ component 0 to 20.0 mol%,
Y ₂ O ₃ component from 0 to 25.0 mol%,
Yb ₂ O ₃ component 0 to 10.0 mol%,
Ta ₂ O ₅ component 0 to 12.0 mol%,
TiO ₂ component 0 to 30.0 mol%,
Nb ₂ O ₅ component 0 to 15.0 mol%,
WO ₃ components 0 to 15.0 mol%,
Li ₂ O component 0 to 50.0 mol%,
ZnO component 0 to 50.0 mol%,
Na ₂ O component from 0 to 25.0 mol%,
K ₂ O component 0 to 20.0 mol%,
Cs ₂ O component 0 to 10.0 mol%,
MgO component 0 to 25.0 mol%,
CaO component 0 to 20.0 mol%,
SrO component 0 to 15.0 mol%,
BaO component 0 to 35.0 mol%,
P ₂ O ₅ component from 0 to 15.0 mol%,
GeO ₂ component 0 to 10.0 mol%,
ZrO ₂ component 0 to 20.0 mol%,
Al ₂ O ₃ component 0 to 20.0 mol%,
Ga ₂ O ₃ component 0-5.0 mol%,
Bi ₂ O ₃ component 0-5.0 mol%,
TeO ₂ component 0-20.0 mol%,
SnO ₂ component 0 to 0.3 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 1.75, more preferably 1.80, still more preferably 1.85, and even more preferably 1.87. The upper limit of this refractive index is preferably 2.20, more preferably 2.15, and even more preferably 2.10. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 35, more preferably 37, and still more preferably 39. The upper limit of this Abbe number may preferably be 50, more preferably 45, still more preferably 43.
Further, the Abbe number (ν _d ) of the optical glass of the present invention satisfies the relationship of (ν _d ) ≧ (−100 × n _d +227.0) with the refractive index (n _d ), and (ν _d ) ≧ (−100 × n _d +227.5) is more preferable, and the relationship (ν _d ) ≧ (−100 × n _d +228.0) is most preferable.
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 1250 ° C, and still more preferably 1200 ° 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, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm. The optical glass of the present invention is spectrally transmitted in a sample having a thickness of 10 mm when expressed by the transmittance of the glass. The upper limit of the wavelength (λ ₇₀ ) exhibiting the rate of 70% is preferably 500 nm, more preferably 450 nm, and still more preferably 410 nm.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, still more preferably 360 nm, and further preferably 340 nm. And
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 low partial dispersion ratio. More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−2.50 × 10 ⁻³ × ν _d +0.6571) ≦ with respect to the Abbe number (ν _d ) ≦ It is preferable to satisfy the relationship (θg, F) ≦ (−2.50 × 10 ⁻³ × ν _d +0.6971). Thereby, since an optical glass having a small partial dispersion ratio (θg, F) is obtained, the optical glass is useful for reducing chromatic aberration of an optical element.
Therefore, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (−2.50 × 10 ⁻³ × ν _d +0.6971), more preferably (−2.50 × 10 ⁻³ ×). (ν _d +0.6921), more preferably (−2.50 × 10 ⁻³ × ν _d +0.6871).
This partial dispersion ratio (θg, F) is preferably (−2.50 × 10 ⁻³ × ν _d +0.6571), more preferably (−2.50 × 10 ⁻³ × ν _d +0.6591), More preferably, (-2.50 × 10 ⁻³ × ν _d +0.6611) may be set as the lower limit.

  The optical glass of the present invention preferably has a glass transition point (Tg) of 720 ° C. or lower. This enables press molding at a lower temperature, and therefore, when producing optical elements by performing mold press molding, reducing the oxidation of the mold used for mold press molding and extending the life of the mold. Can also be planned. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 720 ° C., more preferably 700 ° C., further preferably 685 ° C., and further preferably 650 ° C. The glass transition point is preferably 100 ° C., more preferably 150 ° C., and still more preferably 200 ° C.

[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. 42) and Reference Example (No. A) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg) of these glasses F), liquid phase temperature, wavelengths (λ ₅ and λ ₇₀ ) at which the spectral transmittance is 5% and 70%, and the results of glass transition points are shown in Tables 1 to 6. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glass of the examples of the present invention and the reference examples are ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds and the like 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, the Abbe number, and the partial dispersion ratio (θg, F) of the glasses of Examples and Reference Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. And about the calculated | required Abbe number and the value of partial dispersion ratio, the intercept b in case the inclination a is 0.0025 in relational expression ((theta) g, F) =-a * (nu) _d + b was calculated | required. Here, the refractive index, the Abbe number, and the partial dispersion ratio 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 reference example was measured according to Japan Optical Glass Industry Association standard JOGIS02. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm is measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (transmittance). Wavelength at 70%).

  The liquid phase temperature of the glass of Examples and Reference Examples is as follows. A 30 cc cullet-shaped glass sample was placed 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, the glass transition point (Tg) of the glass of an Example and a reference example was calculated | required by measuring using a horizontal type | mold expansion measuring device. Here, the sample at the time of measurement used the thing of (phi) 4.8mm and length 50-55mm, and the temperature increase rate was 4 degrees C / min.

  All of the optical glasses of the examples of the present invention had a liquidus temperature of 1300 ° C. or lower and were in 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.

In addition, in the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 500 nm or less, more specifically 410 nm or less. In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength when the transmittance was 5%) was 400 nm or less, more specifically 360 nm or less.

Further, the optical glasses of the examples of the present invention all had a refractive index (n _d ) of 1.75 or more, more specifically 1.87 or more, and were within a desired range.

The optical glasses of the examples of the present invention all had an Abbe number (ν _d ) of 35 or more, more specifically 39 or more, and this Abbe number was 50 or less, which was within a desired range. .

In the optical glass of the example of the present invention, the Abbe number (ν _d ) is 227.0 or more than (−100 × n _d ) with respect to the relationship between the refractive index (n _d ) and the Abbe number (ν _d ), More specifically, it was 227.1 or more. On the other hand, in the glass of the reference example, the Abbe number (ν _d ) remained 220.4 larger than (−100 × n _d ). This means that the refractive index (n _d ) is 2.27 or more larger than (−ν _d / 100), and therefore the optical glass of the example of the present invention is more than the glass of the reference example. It was found that it has a higher refractive index in relation to the Abbe number (ν _d ).

Further, the optical glasses of the examples of the present invention all have a partial dispersion ratio (θg, F) of (−2.50 × 10 ⁻³ × ν _d +0.6971) or less, more specifically (−2.50). × 10 ⁻³ × ν _d +0.6818) or less. On the other hand, it was more than the partial dispersion ratio (-2.50 × 10 ⁻³ × ν _d +0.6571) of the optical glass of the example of the present invention. Therefore, it was found that these partial dispersion ratios (θg, F) are within a desired range.

  In addition, the optical glass of the examples of the present invention had a glass transition point of 720 ° C. or less, more specifically 685 ° C. or less, and was within a desired range.

  Therefore, it has been clarified that the optical glass of the example of the present invention has high devitrification resistance, little coloration, and easy press molding while the refractive index and Abbe number are within the desired ranges. .

  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 (20)

The _B 2 _{O 3} component in weight% containing 10.0 to 60.0% of 1.0 to 30.0% and _La 2 _{O 3} component, the content of SiO ₂ component is less 20.0%, An optical glass in which the Abbe number (ν _d ) satisfies the relationship of (ν _d ) ≧ (−100 × n _d +227.0) with the refractive index (n _d ). Gd ₂ O ₃ component by mass% 0-40.0%
Y ₂ O ₃ component 0 to 30.0%
Yb ₂ O ₃ component 0 to 20.0%
The optical glass according to claim 1. _2. The mass sum of Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) is 30.0% or more and 70.0% or less. Or the optical glass of 2. The optical glass according to any one of claims 1 to 3, wherein the content of the Ta ₂ O ₅ component is more than 0% and 30.0% or less. The sum of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) and the Ta ₂ O ₅ component is 45.0% or more and 80. The optical glass according to claim 1, which is 0% or less. The optical glass according to any one of claims 1 to 5, wherein the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 1.0% or more and 30.0% or less. The optical glass according to claim 1, wherein the mass ratio SiO ₂ / B ₂ O ₃ is 0.70 or less. 8. The optical glass according to claim 1, wherein a mass ratio (Ln ₂ O ₃ + Ta ₂ O ₅ ) / (SiO ₂ + B ₂ O ₃ ) is 2.00 or more. 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. Li ₂ O component in mass% 0 to 10.0%
ZnO component 0 to 25.0%
The optical glass according to any one of claims 1 to 10. 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 11. 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. MgO component in mass% 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 25.0%
The optical glass according to any one of claims 1 to 13.   The optical glass according to any one of claims 1 to 14, wherein the RO component (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is 25.0% or less. . _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 15. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 35 or more and 50 or less.   The optical glass according to claim 1, which has a liquidus temperature of 1300 ° C. or lower.   An optical element using the optical glass according to claim 1 as a base material.   An optical apparatus comprising the optical element according to claim 19.