JP6740422B2 - Optical glass and optical element - Google Patents

Description

The present invention relates to an optical glass and an optical element.

In recent years, digitalization and high definition of devices using an optical system have been rapidly advanced, and various optical devices such as photographing devices such as digital cameras and video cameras and image reproducing (projection) devices such as projectors and projection televisions. In the field, there is an increasing demand for reducing the number of optical elements such as lenses and prisms used in the optical system and reducing the weight and size of the entire optical system.

Among optical glasses for producing optical elements, in particular, the optical system has a refractive index ( _nd ) of 1.75 or more and can reduce the weight and size of the entire optical system, and has an Abbe number of 23 or more and 50 or less ( The demand for high-refractive-index, low-dispersion glasses with ν _d ) is very high. As such a high refractive index and low dispersion glass, glass compositions represented by Patent Documents 1 and 2 are known.

JP, 2006-016293, A JP, 2011-144069, A

As a method for producing an optical element from optical glass, for example, a method for obtaining a shape of an optical element by grinding and polishing a gob or a glass block formed from the optical glass, a gob or glass formed from the optical glass. A method of grinding and polishing a glass molded body obtained by reheating a block and molding (reheat press molding), and molding a preform material obtained from a gob or a glass block with an ultra-precision machined mold A method of obtaining the shape of an optical element by (precision mold press molding) is known. Whichever method is used, it is required to obtain stable glass when forming a gob or a glass block from a molten glass raw material .

Here, when the stability of the glass constituting the gob or the glass block to be obtained against devitrification (devitrification resistance) is lowered and crystals are generated inside the glass, it is no longer possible to obtain a glass suitable as an optical element. Can not.

Further, in order to reduce the material cost of the optical glass, it is desired that the raw material costs of the components constituting the optical glass be as low as possible. However, it is difficult to say that the glasses described in Patent Documents 1 and 2 sufficiently meet such requirements.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a stable glass having a refractive index and an Abbe number within desired ranges at a lower cost.

In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive studies to find that the content of the Y ₂ O ₃ component in the glass containing the B ₂ O ₃ component and the La ₂ O ₃ component as essential components. by placing the within a predetermined range, stable glass having a desired high refractive index and high Abbe number while obtained, found that the material cost of the glass is reduced, thereby completing the present invention .. Specifically, the present invention provides the following.

(1) 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 Y 2 _{O 3} component 30.0 % Or less optical glass.

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

(3) The sum of Ln ₂ O ₃ components (wherein Ln is at least one selected from the group consisting of La, Gd, Y, and Yb) is 30.0% or more and 70.0% or less (1 ) Or the optical glass as described in (2).

(4) The optical glass as described in any one of (1) to (3), wherein the mass ratio (Gd ₂ O ₃ +Yb ₂ O ₃ )/(La ₂ O ₃ +Y ₂ O ₃ ) is 0.50 or less.

(5) The optical glass according to any one of (1) to (4), wherein the content of the Ta ₂ O ₅ component is 15.0% or less in mass%.

(6) The optical glass as described in any one of (1) to (5), wherein the sum of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component and the Ta ₂ O ₅ component is 20.0% or less.

(7) WO ₃ component 0 to 25.0% by mass%
Nb ₂ O ₅ component 0 to 20.0%
TiO ₂ component 0 to 20.0%
The optical glass according to any one of (1) to (6).

(8) The optical glass according to any one of (1) to (7), wherein the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component is 1.0% or more and 30.0% or less.

(9) The optical glass as described in any one of (1) to (8), wherein the content of the SiO ₂ component is 20.0% or less in mass %.

(10) The optical glass according to any one of (1) to (9), 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.

(11) The optical glass according to any one of (1) to (10), wherein the mass ratio (Nb ₂ O ₅ +WO ₃ )/(B ₂ O ₃ +SiO ₂ ) is 0.15 or more and 2.00 or less.

(12) 0 to 20.0% by weight of MgO component
CaO component 0-20.0%
SrO component 0-20.0%
BaO component 0 to 25.0%
The optical glass according to any one of (1) to (11).

(13) Any one of (1) to (12) in which the mass sum of 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. Optical glass according to.

(14)% by weight Li ₂ O component from 0 to 10.0%
Na ₂ O component 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 (13).

(15) The sum of masses of the Rn ₂ O components (in the formula, Rn is at least one selected from the group consisting of Li, Na, K, and Cs) is 15.0% or less, and (1) to (14) The optical glass according to any of the above.

(16)% by weight _P 2 _{O 5} component from 0 to 10.0%
GeO ₂ component 0 to 10.0%
ZrO ₂ component 0 to 15.0%
ZnO component 0 to 15.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0 to 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) has 1.75 or more of refractive index _{(n d),} 23 to 50. Abbe number ([nu _d) any description of the optical glass (1) to (16) having a.

(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 using the optical glass according to any one of (1) to (18) as a base material.

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

ADVANTAGE OF THE INVENTION According to this invention, the stable glass which has a refractive index and an Abbe number in a desired range and can contribute to weight reduction of an optical device can be obtained more cheaply.

The optical glass of the present invention contains the B ₂ O ₃ component in an amount of 1.0 to 30.0% and the La ₂ O ₃ component in an amount of 1.0 to 60.0% by mass% based on the total mass of the glass in terms of oxide composition. However, the content of the Y ₂ O ₃ component is 30.0% or less. By containing the La ₂ O ₃ component as an essential component and setting the content of the Y ₂ O ₃ component within a predetermined range, a rare earth element which is expensive and often increases the specific gravity of glass, particularly Gd ₂ Even if O ₃ and Yb ₂ O ₃ are reduced, a high refractive index and Abbe number can be obtained, and an increase in liquidus temperature can be suppressed. Therefore, an optical glass having a high devitrification resistance, which has a refractive index of 1.75 or more and an Abbe's number of 23 or more and 50 or less and which has a small specific gravity and can contribute to weight reduction of optical equipment, can be obtained at a lower cost. be able to.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and is appropriately modified and implemented within the scope of the object of the present invention. be able to. It should be noted that although the description may be omitted as appropriate for the overlapping description, it does not limit the gist of the invention.

[Glass component]
The composition range of each component constituting the optical glass of the present invention will be described below. In the present specification, unless otherwise specified, the content of each component is represented by% by mass based on the total mass of the glass having an oxide-converted composition. Here, the "oxide equivalent composition" means that when the oxide used as a raw material of the glass constituent of the present invention, a complex salt, a metal fluoride and the like are all decomposed during melting and converted into an oxide, It is a composition in which each component contained in the glass is expressed with the total mass of the produced oxide as 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 the B ₂ O ₃ component in an amount of 1.0% or more, the devitrification resistance of the glass can be increased and the dispersion of the glass can be reduced. Therefore, the lower limit of the content of the B ₂ O ₃ component is preferably 1.0%, more preferably 5.0%, further preferably 8.5%, and further preferably 10.5%.
On the other hand, by setting the content of the B ₂ O ₃ component to 30.0% or less, it is possible to easily obtain a larger refractive index and suppress deterioration of chemical durability. Therefore, the upper limit of the content of the B ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, and further preferably 20.0%.
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 glass and reduces dispersion (enlarges Abbe number). In particular, by containing the La ₂ O ₃ component in an amount of 10.0% or more, a desired high refractive index can be obtained. Therefore, the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 20.0%, further preferably 26.0%, further preferably 34.0%, further preferably 39.0%. Is the lower limit.
On the other hand, when the content of the La ₂ O ₃ component is 60.0% or less, the devitrification resistance of the glass can be improved. Therefore, the upper limit of the content of the La ₂ O ₃ component is preferably 60.0%, more preferably 58.0%, further preferably 56.0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La(NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component capable of suppressing the material cost of glass and reducing the specific gravity while maintaining a high refractive index and a high Abbe number when the content exceeds 0%. The Y ₂ O ₃ component is low in material cost among rare earth elements and easily reduces specific gravity as compared with other rare earth elements, and thus is useful for the optical glass of the present invention. Therefore, the content of the Y ₂ O ₃ component may be preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%.
On the other hand, by setting the content of the Y ₂ O ₃ component to 30.0% or less, it is possible to suppress the decrease in the refractive index of the glass and to enhance the devitrification resistance of the glass. Therefore, the upper limit of the content of the Y ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, and further preferably 20.0%.
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 capable of increasing the refractive index of glass and increasing the Abbe number when the content exceeds 0%.
On the other hand, by reducing the Gd ₂ O ₃ component, which is particularly expensive among rare earth elements, to 40.0% or less, the material cost of the glass is reduced, and thus a cheaper optical glass can be manufactured. In addition, this can prevent the Abbe number of the glass from increasing more than necessary. Therefore, the content of the Gd ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, further preferably 20.0%, further preferably 15.0% as the upper limit, and further preferably It is less than 10.0%.
For the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF 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 reduce the dispersion when the content exceeds 0%.
On the other hand, by setting the content of the Yb ₂ O ₃ component to 20.0% or less, the devitrification resistance of the glass can be enhanced. Therefore, the upper limit of the content of the Yb ₂ O ₃ component is preferably 20.0%, more preferably 10.0%, and further preferably 5.0%.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

The sum of the contents of the Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of La, Gd, Y, and Yb) (sum by mass) is 30.0% or more and 75.0% or less. Is preferred.
In particular, by setting this sum to 30.0% or more, the dispersion of glass can be reduced. Therefore, the lower limit of the mass sum of the Ln ₂ O ₃ component is preferably 30.0%, more preferably 40.0%, further preferably 45.0%, and further preferably 54.0%.
On the other hand, by setting this sum to 70.0% or less, the liquidus temperature of the glass becomes low, so that the devitrification resistance can be enhanced. Therefore, the upper limit of the mass sum of the Ln ₂ O ₃ component is preferably 70.0%, more preferably 68.0%, and further preferably 65.0%.

Here, the ratio (mass ratio) of the sum of the contents of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component to the sum of the contents of the La ₂ O ₃ component and the Y ₂ O ₃ component is 0.50 or less. preferable. As a result, the use of expensive Gd ₂ O ₃ component and Yb ₂ O ₃ component is reduced while maintaining a high Abbe number and high transmittance, so that the material cost of glass can be suppressed. Therefore, the mass ratio (Gd ₂ O ₃ +Yb ₂ O ₃ )/(La ₂ O ₃ +Y ₂ O ₃ ) is preferably 0.50, more preferably 0.30, even more preferably 0.22, and even more preferably The upper limit is 0.20.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass and the devitrification resistance when the content exceeds 0%.
On the other hand, by reducing the expensive Ta ₂ O ₅ component to 15.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be manufactured. Further, by setting the content of the Ta ₂ O ₅ component to be 15.0% or less, the melting temperature of the raw material is lowered and the energy required for melting the raw material is reduced, so that the manufacturing cost of the optical glass can also be reduced. .. Therefore, the upper limit of the content of the Ta ₂ O ₅ component is preferably 15.0%, more preferably 13.0%, and further preferably 8.0%. Particularly, from the viewpoint of producing a cheaper optical glass, the content of the Ta ₂ O ₅ component is preferably 5.0%, more preferably 4.0% as the upper limit, and further preferably less than 1.0%. To do.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

Moreover, in the optical glass of the present invention, the sum (mass sum) of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component and the Ta ₂ O ₅ component is preferably 20.0% or less. As a result, the contents of these expensive components are reduced, so that the material cost of glass can be suppressed. Therefore, the mass sum (Gd ₂ O ₃ +Yb ₂ O ₃ +Ta ₂ O ₅ ) is preferably 20.0%, more preferably 15.0%, further preferably 13.0%, further preferably 10.0%. Is the upper limit.

The WO ₃ component is an optional component capable of increasing the refractive index while reducing the coloring of the glass due to other high refractive index components and increasing the devitrification resistance of the glass when the content thereof exceeds 0%. The WO ₃ component is also a component that can lower the glass transition point. Therefore, the lower limit of the content of the WO ₃ component may preferably be more than 0%, more preferably 0.1%, even more preferably 0.5%, and even more preferably 0.6%.
On the other hand, when the content of the WO ₃ component is 25.0% or less, coloring of the glass due to the WO ₃ component can be reduced and the visible light transmittance can be increased. Therefore, the upper limit of the content of the WO ₃ component is preferably 25.0%, more preferably 20.0%, further preferably 15.0%.
As the WO ₃ component, WO ₃ 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 the devitrification resistance when the content is more than 0%. Therefore, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably more than 1.0%, further preferably more than 1.5%, further preferably more than 2.0%, further preferably 4. It may be more than 0%.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 20.0% or less, the devitrification resistance of the glass is lowered and the transmittance of visible light is lowered by the excessive content of the Nb ₂ O ₅ component. Can be suppressed. Therefore, the upper limit of the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, and further preferably 13.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The TiO ₂ component is an optional component that can increase the refractive index of the glass, adjust the Abbe number to be low, and enhance the devitrification resistance when the content exceeds 0%. Therefore, the lower limit of the content of the TiO ₂ component is preferably more than 0%, more preferably 0.5%, and further preferably 1.0%.
On the other hand, by setting the content of TiO ₂ to 20.0% or less, coloring of the glass is reduced, visible light transmittance is increased, and unnecessary reduction of the Abbe number of the glass can be suppressed. Further, devitrification due to excessive inclusion of the TiO ₂ component can be suppressed. Therefore, the content of the TiO ₂ component is preferably 20.0%, more preferably 18.0%, further preferably 15.0% as the upper limit, and further preferably less than 10.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

Here, the sum (mass sum) of the contents of the Nb ₂ O ₅ component and the WO ₃ component is preferably 1.0% or more and 30.0% or less.
In particular, by setting this sum to 1.0% or more, the refractive index of the glass can be increased and the coloring can be reduced even if the Ta ₂ O ₅ component or the rare earth element is reduced in order to reduce the material cost of the glass. And, the devitrification resistance can be enhanced. Therefore, the total mass (Nb ₂ O ₅ +WO ₃ ) preferably has a lower limit of 1.0%, more preferably more than 2.0%, further preferably more than 4.0%, further preferably more than 7.0%. And more preferably more than 8.0%.
On the other hand, by setting this sum to 30.0% or less, coloring and the like due to excessive inclusion of these components can be reduced, and devitrification resistance can be enhanced. Therefore, the upper limit of the mass sum (Nb ₂ O ₅ +WO ₃ ) is preferably 30.0%, more preferably 25.0%, and further preferably 20.0%.

In the optical glass of the present invention, the content of the Ta ₂ O ₅ component is reduced to 15.0% or less and the Nb ₂ O ₅ component is reduced while reducing the B ₂ O ₃ component to 30.0% or less as described above. It is preferable that the sum of the contents of WO ₃ and WO ₃ components is 1.0% or more. As a result, the B ₂ O ₃ component that lowers the refractive index is reduced, while the Nb ₂ O ₅ component and the WO ₃ component that raise the refractive index are contained in a predetermined amount or more, so that the refractive index of the glass is increased. At the same time, the expensive Ta ₂ O ₅ component is reduced among the components that enhance the refractive index and the devitrification resistance, while the cheaper Nb ₂ O ₅ component and WO ₃ component are contained, so that it is more resistant. An optical glass with high devitrification can be obtained. Therefore, the material cost of the optical glass having a high refractive index and a high devitrification resistance can be suppressed. More preferably, the B ₂ O ₃ component is 16.4% or less, the Ta ₂ O ₅ component content is 5.0% or less, and the sum of the Nb ₂ O ₅ component content and the WO ₃ component content is 7%. You may make it 0.0% or more.

The SiO ₂ component is an optional component that can increase the viscosity of the molten glass, reduce the coloring of the glass, and enhance the devitrification resistance when the content exceeds 0%. Therefore, the lower limit of the content of the SiO ₂ component is preferably more than 0%, more preferably 1.0%, and further preferably 3.0%.
On the other hand, by setting the content of the SiO ₂ component to 20.0% or less, it is possible to suppress an increase in the glass transition point and a decrease in the refractive index. Therefore, the upper limit of the content of the SiO ₂ component is preferably 20.0%, more preferably 15.0%, further preferably 10.0%, and further preferably 8.0%.
For the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

Here, 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 setting this sum to 1.0% or more, it is possible to suppress the deterioration of the devitrification resistance due to the deficiency of the B ₂ O ₃ component and the SiO ₂ component. Therefore, the lower limit of the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 1.0%, more preferably 5.0%, and further preferably 10.0%.
On the other hand, by setting this sum to 30.0% or less, the decrease in the refractive index due to the excessive inclusion of these components can be suppressed, so that the desired high refractive index can be easily obtained. Therefore, the upper limit of the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 30.0%, more preferably 25.0%, and further preferably 21.0%.

The ratio (mass ratio) of the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component to the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 0.15 or more and 2.00 or less. ..
In particular, by setting this ratio to 0.15 or more, the refractive index can be increased while maintaining high devitrification resistance. Therefore, the mass ratio (Nb ₂ O ₅ +WO ₃ )/(B ₂ O ₃ +SiO ₂ ) is preferably 0.15, more preferably 0.25, still more preferably 0.30, still more preferably 0.35. More preferably, the lower limit is 0.40.
On the other hand, by the ratio 2.00, suppressing excessive content or _Nb 2 _{O 5} component and WO _{3 components,} a reduction in the devitrification resistance due to absence of the B 2 _{O 3} component and the SiO ₂ component To be Therefore, the upper limit of the mass ratio (Nb ₂ O ₅ +WO ₃ )/(B ₂ O ₃ +SiO ₂ ) is preferably 2.00, more preferably 1.50, and further preferably 1.20.

The MgO component, the CaO component, the SrO component and the BaO component are optional components capable of enhancing the meltability of the glass raw material and the devitrification resistance of the glass when the content thereof exceeds 0%.
On the other hand, by making the content of each of the MgO component, CaO component and SrO component 20.0% or less, and/or the content of BaO component 25.0% or less, A decrease in refractive index and a decrease in devitrification resistance due to excessive content can be suppressed. Therefore, the upper limit of the content of each of the MgO component, CaO component, and SrO component is preferably 20.0%, more preferably 10.0%, and further preferably 5.0%. Moreover, the upper limit of the content of the BaO component is preferably 25.0%, more preferably 15.0%, further preferably 10.0%, and further preferably 8.0%.
The MgO component, the CaO component, the SrO component and the BaO component are MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr(NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba(NO ₃ ) ₂ and BaF ₂ as raw materials. Can be used.

The total content (sum) of the RO components (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 25.0% or less. As a result, it is possible to prevent a decrease in the refractive index and the devitrification resistance of the glass due to the excessive inclusion of the RO component. Therefore, the upper limit of the sum of masses of the RO components is preferably 25.0%, more preferably 15.0%, further preferably 10.0%, and further preferably 5.0%.

The Li ₂ O component, the Na ₂ O component, the K ₂ O component and the Cs ₂ O component are optional components that can improve the glass meltability and lower the glass transition point when the content exceeds 0%. Of these, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component are also components that can enhance the devitrification resistance of the glass. Here, by setting the content of each of the Li ₂ O component, the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component to 10.0% or less, it becomes difficult to lower the refractive index of the glass, and Can improve devitrification resistance. Therefore, the content of each of the Li ₂ O component, Na ₂ O component, K ₂ O component, and Cs ₂ O component is preferably 10.0%, more preferably 8.0%, and further preferably 5.0%. Is the upper limit.
In particular, by setting the content of the Li ₂ O component to 3.0% or less, the viscosity of the glass becomes high, so that the striae of the glass can be reduced. Therefore, from the viewpoint of reducing the striae of the glass, the upper limit of the content of the Li ₂ O component is preferably 3.0%, more preferably 1.0%, and further preferably 0.3%.
The Li ₂ O component, Na ₂ O component, K ₂ O component and Cs ₂ O component are Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ as raw materials. , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ , Cs ₂ CO ₃ , CsNO _{3 and the} like can be used.

The total amount of Rn ₂ O components (wherein Rn is at least one selected from the group consisting of Li, Na, K, and Cs) is preferably 15.0% or less. This makes it possible to suppress the decrease in the refractive index of the glass and enhance the devitrification resistance. Therefore, the upper limit of the mass sum of the Rn ₂ O component is preferably 15.0%, more preferably 10.0%, and further preferably 5.0%.

The P ₂ O ₅ component is an optional component that can enhance the devitrification resistance of the glass when the content exceeds 0%. In particular, by setting the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress the decrease in the chemical durability of the glass, particularly the water resistance. Therefore, the upper limit of the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and further 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 capable of increasing the refractive index of glass and improving the devitrification resistance when the content exceeds 0%. However, since the raw material price of GeO ₂ is high, the material cost increases when the amount thereof is large, and the effect of cost reduction by reducing the Gd ₂ O ₃ component and Ta ₂ O ₅ component is diminished. Therefore, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, further preferably 1.0%, and the most preferably not included.
For 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 the high refractive index and low dispersion of the glass and can enhance the devitrification resistance of the glass. Therefore, the lower limit of the ZrO ₂ component content is preferably more than 0%, more preferably 1.0%, and further preferably 3.0%.
On the other hand, by setting the ZrO ₂ component to 15.0% or less, it is possible to prevent the devitrification resistance of the glass from being lowered due to the excessive inclusion of the ZrO ₂ component. Therefore, the upper limit of the ZrO ₂ component content is preferably 15.0%, more preferably 10.0%, and even more preferably 8.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ 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 enhance the chemical durability when the content exceeds 0%.
On the other hand, by setting the content of the ZnO component to be 15.0% or less, it is possible to suppress a decrease in the refractive index of the glass and a decrease in the devitrification resistance. Further, this increases the viscosity of the molten glass, so that the occurrence of striae in the glass can be reduced. Therefore, the upper limit of the ZnO component content is preferably 15.0%, more preferably 10.0%, even more preferably less than 5.0%, and further preferably 1.1%.
For the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components capable of enhancing the chemical durability of the glass and enhancing the devitrification resistance of the glass when the content thereof exceeds 0%.
On the other hand, by setting the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, it is possible to suppress the deterioration of the devitrification resistance of the glass due to the excessive content thereof. Therefore, the upper limit of 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 further preferably 3.0%.
As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga(OH) ₃ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component capable of increasing the refractive index and decreasing the glass transition point when the content 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 upper limit of the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and further preferably 3.0%.
For 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 capable of increasing the refractive index and decreasing the glass transition point when the content exceeds 0%.
However, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which a portion in contact with the molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 20.0%, more preferably 10.0%, further preferably 5.0% as the upper limit, and further preferably no content.
As the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an optional component which, when contained in an amount of more than 0%, can reduce the oxidization of the molten glass to clarify it and 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, coloring of the glass due to reduction of the molten glass and devitrification of the glass can be reduced. Further, alloying of the SnO ₂ component and the melting equipment (particularly noble metal such as Pt) is reduced, so that the life of the melting equipment can be extended. Therefore, the upper limit of the content of the SnO ₂ component is preferably 1.0%, more preferably 0.7%, and even 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 is contained in an amount of more than 0%.
On the other hand, if the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region becomes poor. Therefore, the upper limit of the Sb ₂ O ₃ component content is preferably 1.0%, more preferably 0.7%, and even more preferably 0.5%.
Sb ₂ O ₃ component can be used _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O and the like as raw materials.

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

<Ingredients that should not be contained>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferable to be contained will be described.

Other components can be added, if necessary, within a range that does not impair the characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, except Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is used alone. Alternatively, even if a small amount is included in the composite, the glass is colored and has a property of causing absorption at a specific wavelength in the visible region. Therefore, in an optical glass using a wavelength in the visible region, it is preferable not to include substantially. ..

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

Furthermore, in recent years, Th, Cd, Tl, Os, Be, and Se components have tended to be refrained from being used as harmful chemical substances, and are not only used in the glass manufacturing process but also in the processing process and post-commercial disposal. Environmental measures need to be taken. Therefore, when importance is attached to the influence on the environment, it is preferable that they are not substantially contained.

The glass composition of the present invention cannot be directly represented in the description of mol% because the composition is represented by mass% based on the total mass of the glass in terms of oxide composition, but various characteristics required in the present invention The composition represented by mol% of each component present in the glass composition satisfying the above conditions takes approximately the following values in terms of oxide.
B ₂ O ₃ component from 2.0 to 55.0 mol%, and _La 2 _{O 3} component from 5.0 to 30.0 mol%,
And Y ₂ O ₃ component 0 to 20.0 mol %,
Gd ₂ O ₃ component 0 to 20.0 mol%,
Yb ₂ O ₃ component 0 to 10.0 mol%,
Ta ₂ O ₅ component 0-5.0 mol%,
WO ₃ component 0 to 20.0 mol%,
Nb ₂ O ₅ component 0 to 15.0 mol%,
TiO ₂ component 0 to 40.0 mol%,
SiO ₂ component 0 to 50.0 mol %,
MgO component 0-50.0 mol%,
CaO component 0-40.0 mol%,
SrO component 0 to 30.0 mol%,
BaO component 0 to 35.0 mol%,
Li ₂ O component 0 to 30.0 mol%,
Na ₂ O component 0 to 25.0 mol%,
K ₂ O component 0 to 20.0 mol%,
Cs ₂ O component 0 to 10.0 mol%,
P ₂ O ₅ component 0 to 15.0 mol%,
GeO ₂ component 0 to 10.0 mol%,
ZrO ₂ component 0 to 20.0 mol%,
ZnO component 0-50.0 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 to 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 were uniformly mixed so that each component was within a predetermined content range, the prepared mixture was put into a platinum crucible, and the temperature was set to 1100 to 1500° C. in an electric furnace depending on the difficulty of melting the glass composition. It is prepared by melting in the temperature range of 2 to 5 hours, stirring and homogenizing, lowering to an appropriate temperature, casting in a mold, and then slowly 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 lower limit of the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.75, more preferably 1.80, and further preferably 1.85. The upper limit of this refractive index may be preferably 2.20, more preferably 2.15, and further preferably 2.10. In addition, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 23, more preferably 25, further preferably 28, further preferably 30, further preferably 31, and further preferably 32, and the lower limit is preferably The upper limit is 50, more preferably 45, and further preferably less than 39.
By having such a high refractive index, a large amount of refraction of light can be obtained even when the optical element is made thin. Further, by having such low dispersion, even with a single lens, the shift of the focus (chromatic aberration) due to the wavelength of light is reduced. In addition, by having such a low dispersion, it is possible to achieve high imaging characteristics and the like when combined with an optical element having a high dispersion (low Abbe number), for example.
Therefore, the optical glass of the present invention is useful for optical design, and while achieving particularly high imaging characteristics, the optical system can be downsized and the degree of freedom in optical design can be expanded.

Further, the optical glass of the present invention preferably has a low specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 5.50 [g/cm ³ ] or less. This reduces the mass of the optical element and the optical device using the optical element, which can contribute to the weight reduction of the optical device. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 5.50, more preferably 5.40, and preferably 5.30. The specific gravity of the optical glass of the present invention is generally 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more.
The specific gravity of the optical glass of the present invention is measured based on the Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method for measuring specific gravity of optical glass".

The optical glass of the present invention preferably has high devitrification resistance, and more specifically has 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 1290°C, and further preferably 1280°C. As a result, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is reduced, so that devitrification particularly when the glass is formed from the molten state can be reduced, and the optical element using the glass can be reduced. Can reduce the influence on the optical characteristics. Further, since the glass can be molded even if the melting temperature of the glass is lowered, it is possible to reduce the manufacturing cost of the glass by suppressing the energy consumed during the molding of the 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., further preferably 700° C. as the lower limit. Good. In addition, the "liquidus temperature" in this specification means that a 30 cc cullet-shaped glass sample is put into a platinum crucible having a capacity of 50 ml and completely melted at 1350° C., and the temperature is lowered to a predetermined temperature. The glass surface and the presence/absence of crystals in the glass are observed immediately after cooling for 12 hours and taken out of the furnace to show the lowest temperature at which no crystals are observed. The predetermined temperature when the temperature is lowered here is a temperature in steps of 10° C. up to 1300° C.

It is preferable that the optical glass of the present invention has a high visible light transmittance, in particular, a light transmittance on the short wavelength side of the visible light, and thus the coloring is small.
In particular, the optical glass of the present invention has a wavelength (λ ₇₀ ) at which a sample having a thickness of 10 mm and a spectral transmittance of 70% is represented by a glass transmittance, preferably 550 nm, more preferably 520 nm, further preferably 500 nm. More preferably, the upper limit is 480 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 440 nm, more preferably 420 nm, further preferably 400 nm, and further preferably 380 nm is the upper limit. And
These make the absorption edge of the glass close to the ultraviolet region and enhance the transparency of the glass with respect to visible light. Therefore, this optical glass can be preferably used for an optical element such as a lens that transmits light.

The optical glass of the present invention preferably has a low partial dispersion ratio (θg, F). 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 the Abbe number (ν _d ). It is preferable that the relationship of (θg, F)≦(−2.50×10 ⁻³ ×ν _d +0.6971) is satisfied. As a result, an optical glass having a small partial dispersion ratio (θg, F) can be obtained, and thus the optical glass can be used to reduce chromatic aberration of the 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 +0.6571), and more preferably (−2.50×10 ⁻³ ×). ν _d +0.6591), and more preferably (−2.50×10 ⁻³ ×ν _d +0.6611).
On the other hand, 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). Xν _d +0.6921), and more preferably (−2.50×10 ⁻³ ×ν _d +0.6871).

[Glass molded article and optical element]
A glass molded product can be produced from the produced optical glass by using, for example, a polishing process means or a mold press molding means such as reheat press molding or precision press molding. That is, optical glass is subjected to mechanical processing such as grinding and polishing to produce a glass molded body, or preform made from optical glass is subjected to reheat press molding and then polishing processing is performed to perform glass molding. A glass molded body can be manufactured by producing a body or performing precision press molding on a preform produced by performing a polishing process or a preform formed by a known float forming. 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 preferably used for optical elements such as lenses and prisms. As a result, it becomes possible to form a glass molded body with a large diameter. Therefore, while enlarging the optical element, high-definition and high-precision imaging characteristics and projection characteristics can be achieved when used in optical equipment such as cameras and projectors. The characteristics can be realized.

The composition of the embodiment of the present invention (No.1~No.132) and Comparative Example (No. A), and the refractive index of these glasses _(n d), Abbe number ([nu _d), the partial dispersion ratio ([theta] g , F), liquidus temperature, wavelengths (λ ₅ and λ ₇₀ ) at which spectral transmittances are 5% and 70%, and specific gravity are shown in Tables 1 to 19. It should be noted that the following embodiments are merely for the purpose of illustration, and the embodiments are not limited thereto.

The glasses of Examples and Comparative Examples of the present invention are ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc., each of which corresponds to the raw material of each component. The high-purity raw material used for was selected, weighed and uniformly mixed so as to have the composition ratio of each example shown in the table, and then charged into a platinum crucible, depending on the melting difficulty of the glass composition. After melting in an electric furnace in a temperature range of 1100 to 1500° C. for 2 to 5 hours, the mixture was stirred and homogenized, then 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 glass of Examples and Comparative Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, for the values of the obtained Abbe number and the partial dispersion ratio, the intercept b when the slope a was 0.0025 in the relational expression (θg, F)=−a×ν _d +b was obtained. Here, the refractive index, the Abbe's number, and the partial dispersion ratio were determined by measuring the glass obtained at a slow cooling rate of -25°C/hr.

Further, the transmittances of the glasses of Examples and Comparative Examples were measured according to Japan Optical Glass Industry Association Standard JOGIS02. In the present invention, the presence or absence and the degree of coloring of the glass were determined by measuring the transmittance of the glass. Specifically, a face-to-face parallel polished product having a thickness of 10±0.1 mm was measured for spectral transmittance at 200 to 800 nm according to JIS Z8722, and λ ₅ (wavelength at 5% transmittance) and λ ₇₀ (transmittance) were measured. The wavelength at 70%) was determined.

Further, the liquidus temperature of the glass of Examples and Comparative Examples is 1300° C. to 1160° C., in which a 30 cc cullet-shaped glass sample was put into a platinum crucible with a capacity of 50 ml and completely melted at 1350° C. The temperature is lowered to any of the temperatures set in steps of 10°C and kept for 12 hours, taken out of the furnace and immediately cooled, and then the presence or absence of crystals on the glass surface and the glass is observed. The temperature was determined.

The specific gravities of the glass of Examples and Comparative Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method of measuring specific gravity of optical glass".

The optical glasses of the examples of the present invention each had a specific gravity of 5.50 or less, more specifically 5.20 or less. Therefore, it was revealed that the optical glass of the example of the present invention has a small specific gravity.

Further, the optical glass of each of the examples of the present invention had a liquidus temperature of 1300° C. or lower, more specifically 1220° C. or lower, which was within the desired range. Therefore, it was revealed that the optical glass of the example of the present invention has a low liquidus temperature and high devitrification resistance.

Further, the optical glasses of the examples of the present invention each had a λ ₇₀ (wavelength at a transmittance of 70%) of 550 nm or less, more specifically 505 nm or less. Further, the optical glasses of the examples of the present invention each had a λ ₅ (wavelength at a transmittance of 5%) of 440 nm or less, more specifically 379 nm or less.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.75 or more, with more detail is 1.87 or more, the refractive index is 2.20 or less, more detail Was 2.01 or less, which was within the desired range.

Further, in each of the optical glasses of Examples of the present invention, the Abbe number (ν _d ) is 23 or more, more specifically 28 or more, and the Abbe number is 50 or less, more specifically 39 or less, It was within the desired range.

Further, the optical glasses of the examples of the present invention each have a partial dispersion ratio (θg, F) of (−2.50×10 ⁻³ ×ν _d +0.6571) or more, more specifically (−2.50). ×10 ⁻³ ×ν _d +0.6683) or more. On the other hand, the partial dispersion ratio (−2.50×10 ⁻³ ×ν _d +0.6971) of the optical glass of the example of the present invention or less, more specifically (−2.50×10 ⁻³ ×ν _{d ).} +0.6750) or less. Therefore, it was found that these partial dispersion ratios (θg, F) were within the desired range.

Therefore, it is apparent that the optical glass of the examples of the present invention can be manufactured at low cost while the refractive index and the Abbe number are within the desired ranges, the devitrification resistance is high, the coloring is small, and the specific gravity is small. became.

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

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

Claims (6)

% By mass _B 2 _{O 3} ingredient 1.0 to 13.90%,
La ₂ O ₃ component 39.0 to 56.0 %
Y ₂ O ₃ ingredient from 1.80 to 20.0%,
Nb ₂ O ₅ component is more than 1.0% and not more than 15.0%,
9.20% or more and 20.0% or less of TiO ₂ component, and
Containing WO ₃ component in an amount of 0.5% or more and 15.0% or less ,
The content of Gd ₂ O ₃ component is 2.80% or less,
The content of the Yb ₂ O ₃ component is 2.80% or less,
The content of SiO ₂ component is 15.0% or less,
Ta ₂ O ₅ Ri is 1.0% less than <br/> der content of the component,
The sum of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component and the Ta ₂ O ₅ component is 2.80% or less,
Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of La, Gd, Y, and Yb) has a mass sum of 45.0% or more and 65.0% or less,
An optical glass having a refractive index ( _nd ) of 1.75 or more and an Abbe number (ν _d ) of 23 or more and 50 or less . The optical glass according to claim 1, wherein the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component is 1.0% or more and 25.0 % or less. The optical glass according to claim 1 or 2 , wherein the mass ratio (Nb ₂ O ₅ +WO ₃ )/(B ₂ O ₃ +SiO ₂ ) is 0.15 or more and 1.50 or less. Any description of the optical glass of claims 1 to 3, having 1300 ° C. below the liquidus temperature. Optical elements of the optical glass as a base material according to any of claims 1 to 4. An optical device comprising the optical element according to claim 5 .