TWI621599B - Optical glass, preforms and optical components - Google Patents

Abstract

The present invention provides an optical glass which can obtain a preform having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and which is easy to be subjected to precision press molding and has high devitrification resistance. , preforms and optical components.

The optical glass of the present invention contains 10.0% or more and 50.0% or less of the B ₂ O ₃ component, 5.0% or more and 30.0% or less of the La ₂ O ₃ component, and has a refractive index (n _d ) of 1.80 or more in terms of mol%. Abbe number (ν _d ) of 30 or more and 45 or less.

Description

Optical glass, preforms and optical components

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

In recent years, the digitalization or high definition of devices using optical systems has been rapidly developed in the field of various optical devices such as digital cameras or video cameras, such as photographic equipment, projectors, or projection televisions such as projection televisions. The reduction in the number of optical elements such as lenses or cymbals used in optical systems has become increasingly demanding in terms of weight reduction and miniaturization of the optical system as a whole.

Among the optical glasses for producing an optical element, in particular, it is possible to reduce the weight and size of the optical system as a whole, and to have a refractive index (n _d ) of 1.80 or more and an Abbe number (ν _d ) of 30 or more and 45 or less. The demand for high refractive index low dispersion glass which can be precision molded is remarkably improved. As such a high refractive index low-dispersion glass, a glass composition represented by the glasses of Patent Documents 1 to 4 is known.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 06-305769

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-137662

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-240889

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2008-201661

The lenses used in the optical system include a spherical lens and an aspherical lens. If an aspherical lens is used, the number of optical elements can be reduced. Further, it is known that various optical elements other than lenses also include faces having a complicated shape. However, if the previous grinding and grinding steps are to be used to obtain an aspherical or complex shaped surface, the cost is high and complicated work steps are required. Therefore, the current mainstream is a method of obtaining a shape of an optical element by directly pressing and molding a preform obtained from a billet or a glass brick by an ultra-precision machined mold, that is, a method of performing precision press forming.

Further, in addition to the method of precisely molding a preform into a preform, it is also known to reheat and form a billet or a glass brick formed of a glass material (reheat press forming), and to grind and grind the obtained glass molded body. method.

As a method for producing a preform for use in such precision press forming or reheat press forming, there is a method of directly producing from molten glass by a dropping method, or a glass brick is heated by pressing or grinding into a spherical shape and obtained. The method of grinding and grinding the processed product. In order to obtain an optical element by molding the molten glass into a desired shape, it is easy to perform precision press molding in any method, and it is difficult to devitrify the formed glass.

Further, in order to reduce the material cost of the optical glass, it is expected that the raw material cost of each component constituting the optical glass is as inexpensive as possible. Further, in order to reduce the manufacturing cost of the optical glass, it is expected that the melting property of the raw material is high, that is, it is melted at a lower temperature. However, the glass compositions described in Patent Documents 1 to 4 are difficult to cope with the above various requirements.

The present invention has been made in view of the above problems, and an object thereof is to obtain a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range at a lower cost, and it is easy to perform precision press molding and resistance to devitrification. High preforms.

In order to solve the above problems, the inventors of the present invention have repeatedly tried their best to conduct experimental studies and found that a refractive index (n _d ) and an Abbe number (ν _d ) can be obtained in a glass containing a B ₂ O ₃ component and a La ₂ O ₃ component. The optical glass of the precision press molding is easily carried out within the required range, thereby completing the present invention.

The present inventors have found, inter alia, that a refractive index (n _d ) and an Abbe number (ν _d ) are obtained within a desired range, and a Gd ₂ O ₃ component and a Ta ₂ O ₅ component having a high material cost are obtained. The optical glass is reduced in content and is easily subjected to precision press molding.

Further, the inventors of the present invention have found that a refractive index (n _d ) and an Abbe number (ν _d ) can be obtained within a desired range, and contain a material which is low in cost in a component which contributes to high refractive index and high dispersion. Y ₂ O ₃ component, and it is easy to perform precision press molding of optical glass.

Specifically, the present invention provides the following.

(1) An optical glass containing 10.0% or more and 50.0% or less of a B ₂ O ₃ component, 5.0% or more and 30.0% or less of a La ₂ O ₃ component, and a refractive index of 1.80 or more in a molar percentage (n _{d )} ), having an Abbe number (ν _d ) of 30 or more and 45 or less.

(2) The optical glass according to (1), wherein the content of the Y ₂ O ₃ component is 20.0% or less in terms of mol%.

(3) The optical glass according to (1) or (2), which contains the Y ₂ O ₃ component in an amount of more than 0% and 20.0% or less in terms of mol%.

(4) The optical glass according to any one of (1) to (3) wherein the content of the Y ₂ O ₃ component is 10.0% or less in terms of mol%.

The optical glass according to any one of (1) to (4), wherein the Gd ₂ O ₃ component is 0 to 10.0% and the Yb ₂ O ₃ component is 0 to 10.0% in terms of Mo %. _{The 2} O ₃ component is 0 to 10.0%.

(6) The optical glass according to any one of (1) to (5) wherein the content of the Ta ₂ O ₅ component is 10.0% or less in terms of mol%.

The optical glass according to any one of (1) to (6), wherein the molar and (Gd ₂ O ₃ + Yb ₂ O ₃ + Ta ₂ O ₅ ) are 10.0% or less.

(8) The optical glass according to any one of (1) to (7) wherein the molar and (Gd ₂ O ₃ + Ta ₂ O ₅ ) are less than 5.0%.

The optical glass according to any one of (1) to (8) wherein the content of the Ta ₂ O ₅ component is less than 1.0% in terms of mol%.

(10) The optical glass according to any one of (1) to (9) wherein the content of the Gd ₂ O ₃ component is less than 1.0% in terms of mol%.

(11) The optical glass according to any one of (1) to (10) wherein the Ln ₂ O ₃ component (wherein Ln is selected from the group consisting of La, Gd, Y, Yb, and Lu) The molar ratio of the above) is 10.0% or more and 40.0% or less.

(12) The optical glass according to any one of (1) to (11) which contains two or more of the above-mentioned Ln ₂ O ₃ components.

The optical glass according to any one of (1) to (12), wherein the TiO ₂ component is 0 to 20.0% and the Nb ₂ O ₅ component is 0 to 10.0% in terms of mol%.

The optical glass according to any one of (1) to (13), wherein the content of the WO ₃ component is 20.0% or less in terms of mol%.

The optical glass according to any one of (1) to (14) which contains the WO ₃ component in an amount of 1.0% or more and 20.0% or less in terms of mol%.

The optical glass according to any one of (1) to (15) wherein the molar and (TiO ₂ + WO ₃ + Nb ₂ O ₅ ) are 1.0 to 30.0%.

(17) The optical glass according to any one of (1) to (16), wherein the ZnO component is contained in an amount of 10.0% or more and 38.0% or less in terms of mol%.

The optical glass according to any one of (1) to (17) wherein the content of the ZrO ₂ component is 10.0% or less in terms of mol%.

The optical glass according to any one of (1) to (18), wherein the content of the SiO ₂ component is 15.0% or less in terms of mol%.

(20) The optical glass according to any one of (1) to (19) wherein the content of the Li ₂ O component is 8.0% or less in terms of mol%.

The optical glass according to any one of (1) to (20) wherein the Na ₂ O component is 0 to 15.0%, and the K ₂ O component is 0 to 10.0%, Cs ₂ O. The composition is 0~10.0%.

The optical glass according to any one of (1) to (21), wherein the Rn ₂ O component (wherein Rn is selected from one or more of the group consisting of Li, Na, K, and Cs) The molar ratio is 20.0% or less.

The optical glass according to any one of (1) to (22), wherein the MgO component is 0 to 10.0%, the CaO component is 0 to 10.0%, and the SrO component is 0 to 10.0%. The BaO component is 0 to 10.0%.

The optical glass according to any one of (1) to (23), wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is a molar. The sum is 11.0% or less.

The optical glass according to any one of (1) to (24), wherein the GeO ₂ component is 0 to 10.0%, and the P ₂ O ₅ component is 0 to 10.0%, Bi ₂ O. ₃ components are 0 to 15.0%, TeO ₂ components are 0 to 15.0%, Al ₂ O ₃ components are 0 to 15.0%, Ga ₂ O ₃ components are 0 to 15.0%, and Sb ₂ O ₃ components are 0 to 1.0%. Further, the content of the fluoride in which one or both of the oxides of one or more of the above elements are replaced by F is from 0 to 15.0 mol%.

The optical glass according to any one of (1) to (25) which has a refractive index (n _d ) of 1.80 or more and 1.95 or less, and has an Abbe number (ν _d ) of 30 or more and 45 or less. .

The optical glass according to any one of (1) to (26), wherein the glass transition point (Tg) exceeds 580 ° C and is 630 ° C or lower.

The optical glass according to any one of (1) to (27) which has a liquidus temperature of 1100 ° C or lower.

(29) A preform comprising the optical glass according to any one of (1) to (28).

(30) An optical element produced by press molding a preform according to (29).

(31) An optical element comprising the optical glass according to any one of (1) to (28) as a base material.

(32) An optical device comprising the optical element according to (30).

(33) An optical device comprising the optical element according to (31).

According to the present invention, it is possible to obtain a preform having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and which is easy to perform precision press molding and has high devitrification resistance.

The optical glass of the present invention contains 10.0% or more and 50.0% or less of the B ₂ O ₃ component, 5.0% or more and 30.0% or less of the La ₂ O ₃ component, and has a refractive index (n _d ) of 1.80 or more in terms of mol%. Abbe number (ν _d ) of 30 or more and 45 or less.

In particular, the first optical glass contains 10.0% or more and 50.0% or less of the B ₂ O ₃ component, and 5.0% or more and 30.0% or less of the La ₂ O ₃ component in terms of mol%, and Mor and (Gd ₂ O ₃ + Ta ₂ O ₅ ) Less than 5.0%, and having a refractive index (n _d ) of 1.80 or more, having an Abbe number (ν _d ) of 30 or more and 45 or less.

Further, the second optical glass contains 10.0% or more and 50.0% or less of the B ₂ O ₃ component, 5.0% or more and 30.0% or less of the La ₂ O ₃ component, and more than 0% and 20.0% or less of the Y ₂ O ₃ component. And having a refractive index (n _d ) of 1.80 or more, and having an Abbe number (ν _d ) of 30 or more and 45 or less.

In particular, in the first optical glass, the material cost of the glass can be lowered by lowering the content of the Gd ₂ O ₃ component and the Ta ₂ O ₅ component. On the other hand, in particular, the second optical glass can reduce the material cost of the glass by containing the Y ₂ O ₃ component. Further, based on the B ₂ O ₃ component and the La ₂ O ₃ component, the refractive index (n _d ) of 1.80 or more and 1.95 or less and the Abbe number (ν _d ) of 30 or more and 45 or less, and the liquid The phase temperature becomes easy to decrease.

The inventors of the present invention have found that by having a refractive index (n _d ) of 1.80 or more and 1.95 or less and an Abbe number (ν _d ) of 30 or more and 45 or less, the Gd ₂ O ₃ component having a high material cost is lowered and The content of the Ta ₂ O ₅ component additionally contains a Y ₂ O ₃ component which is low in material cost in a component which contributes to high refractive index and high dispersion, and adjusts the content of each component so as to be optical glass having a lower glass transition point. In contrast, the devitrification of the glass can be reduced, whereby a glass which is more easily press-formed can be obtained.

According to the above, it is possible to inexpensively obtain the optical fiber of the preform which can obtain the refractive index (n _d ) and the Abbe number (ν _d ) within a desired range, and which is easy to perform precision press molding and has high devitrification resistance. glass.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be appropriately modified and implemented within the scope of the object of the present invention. In addition, in the case where there is a repetition of the description, the description may be appropriately omitted, but the gist of the invention is not limited.

[Glass composition]

The composition range of each component constituting the optical glass of the present invention will be described below. In the present specification, regarding the content of each component, when there is no special regulation, all The mole % of the total mass of the glass in terms of oxide conversion composition is expressed. Here, the "oxide-converting composition" is obtained by oxidizing an oxide, a composite salt, and a metal fluoride which are assumed to be used as a raw material of the glass constituent component of the present invention, when they are all decomposed and converted into an oxide at the time of melting. The total mass of the substance was set to 100 mol% and represents the composition of each component contained in the glass.

<About essential ingredients, optional ingredients>

In the optical glass of the present invention containing a large amount of rare earth oxides, the B ₂ O ₃ component is an essential component as a glass forming oxide. In particular, by setting the content of the B ₂ O ₃ component to 10.0% or more, the devitrification resistance of the glass can be improved, and the Abbe number of the glass can be increased. Therefore, the content of the B ₂ O ₃ component is preferably 10.0% as the lower limit, more preferably 15.0% as the lower limit, still more preferably 20.0% as the lower limit, and still more preferably 25.0% as the lower limit.

On the other hand, by setting the content of the B ₂ O ₃ component to 50.0% or less, a larger refractive index can be easily obtained, and deterioration in chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably an upper limit of 50.0%, more preferably an upper limit of 45.0%, and still more preferably an upper limit of 40.0%.

As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ can be used. 10H ₂ O, BPO ₄ and the like are used as raw materials.

The La ₂ O ₃ component is an essential component for increasing the refractive index of the glass and increasing the Abbe number of the glass. Therefore, the content of the La ₂ O ₃ component is preferably 5.0% as the lower limit, more preferably 10.0% as the lower limit, and still more preferably 13.0% as the lower limit.

On the other hand, by making the content of the La ₂ O ₃ component 30.0% or less, the stability of the glass is improved, whereby devitrification can be reduced. Therefore, the content of the La ₂ O ₃ component is preferably 30.0% as the upper limit, more preferably 25.0%, and more preferably 20.0% as the upper limit, and further preferably 20.0%. Jiawei is capped at 17.0%.

As the La ₂ O ₃ component, La ₂ O ₃ or La(NO ₃ ) ₃ can be used. XH ₂ O (X is an arbitrary integer) or the like is used as a raw material.

The Y ₂ O ₃ component is an optional component which can maintain a high refractive index and a high Abbe number while suppressing the material cost of the glass, and can lower the specific gravity of the glass as compared with other rare earth components. In particular, in the second optical glass, the Y ₂ O ₃ component is an essential component. Therefore, the content of the Y ₂ O ₃ component is preferably a lower limit of more than 0%, more preferably a lower limit of 0.5%, still more preferably a lower limit of 1.0%, and still more preferably a lower limit of 2.0%. The lower limit is 3.0%.

On the other hand, by setting the content of the Y ₂ O ₃ component to 20.0% or less, the decrease in the refractive index of the glass can be suppressed, and the devitrification resistance of the glass can be improved. Therefore, the content of the Y ₂ O ₃ component is preferably an upper limit of 20.0%, more preferably an upper limit of 10.0%, still more preferably an upper limit of 8.0%, and still more preferably an upper limit of 6.0%.

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 can increase the refractive index of the glass when it contains more than 0%, and can increase the Arbe number.

On the other hand, since the material cost of the glass is lowered by making the Gd ₂ O ₃ component which is particularly expensive among the rare earth elements less than 10.0%, the optical glass can be produced at a lower cost. Further, by this, it is possible to suppress the Abbe number of the glass from excessively rising. Therefore, the content of the Gd ₂ O ₃ component is preferably set to less than 10.0%, more preferably less than 5.0%, still more preferably less than 1.0%, and further preferably less than 0.5. % is further preferably set to less than 0.3%, and more preferably set to less than 0.1%.

As 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 and the Lu ₂ O ₃ component are optional components which increase the refractive index of the glass and increase the Abbe number when the content exceeds 0%.

On the other hand, by setting the content of the Yb ₂ O ₃ component and the Lu ₂ O ₃ component to 10.0% or less, the material cost of the glass can be reduced, and thus the optical glass can be produced at a lower cost. Moreover, the devitrification resistance of the glass can be improved by this. Therefore, the content of the Yb ₂ O ₃ component and the Lu ₂ O ₃ component is preferably an upper limit of 10.0%, more preferably an upper limit of 5.0%, still more preferably an upper limit of 3.0%, and further preferably 1.0. % is the upper limit, and further preferably 0.1% as the upper limit. From the viewpoint of reducing the material cost, the Yb ₂ O ₃ component and the Lu ₂ O ₃ component may not be contained.

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

The Ta ₂ O ₅ component is an optional component which increases the refractive index of the glass and increases the resistance to devitrification when it contains more than 0%.

On the other hand, by making the expensive Ta ₂ O ₅ component less than 10.0%, the material cost of the glass can be reduced, and thus the optical glass can be produced at a lower cost. Further, since the melting temperature of the raw material is lowered, the energy required for the melting of the raw material is lowered, so that the manufacturing cost of the optical glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 1.0%, and still more preferably 0.7% or less. Further, it is preferably 0.4% or less, more preferably less than 0.3%, still more preferably 0.2% or less, and still more preferably 0.1% or less.

As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

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 preferably 10.0% or less. Thereby, the content of such expensive components can be reduced, and thus the material cost of the glass can be suppressed. Therefore, it is preferable that Mo and (Gd ₂ O ₃ + Yb ₂ O ₃ + Ta ₂ O ₅ ) have an upper limit of 10.0%, more preferably an upper limit of 7.0%, and still more preferably an upper limit of 5.0%. The upper limit is preferably 3.5%, more preferably 2.0%, more preferably 1.0%, and even more preferably less than 0.5%.

The total amount of the Gd ₂ O ₃ component and the Ta ₂ O ₅ component is preferably less than 5.0%. Thereby, the content of such expensive components can be reduced, and thus the material cost of the glass can be suppressed. Therefore, Mo and (Gd ₂ O ₃ + Ta ₂ O ₅ ) are preferably set to be less than 5.0%, more preferably set to 3.5% or less, further preferably set to less than 1.0%, and more preferably Set to less than 0.5%.

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) is preferably 10.0% or more and 40.0% or less. .

In particular, by setting the sum to be 10.0% or more, both the refractive index and the Abbe number of the glass can be improved, so that a glass having a desired refractive index and Abbe number can be easily obtained. Therefore, the molar content of the Ln ₂ O ₃ component is preferably 10.0% as the lower limit, more preferably 15.0% as the lower limit, further preferably 16.0% as the lower limit, and more preferably 17.0% as the lower limit, and more preferably 17.0% as the lower limit. Jia is the lower limit of 18.0%.

On the other hand, by lowering the liquid phase temperature of the glass by making the sum 40.0% or less, devitrification of the glass can be reduced. Therefore, the molar content of the Ln ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, more preferably 25.0%, and still more preferably 22.0%.

The optical glass of the present invention preferably contains two or more of the above-mentioned Ln ₂ O ₃ components. Thereby, the temperature of the liquid phase of the glass becomes lower, and thus a glass having higher devitrification resistance can be obtained. In terms of easily lowering the liquidus temperature of the glass and producing an inexpensive optical glass, it is particularly preferable to contain two or more components including a La ₂ O ₃ component and a Y ₂ O ₃ component as Ln ₂ O _{3 .} ingredient.

When the TiO ₂ component contains more than 0%, the refractive index and Abbe number of the glass can be increased, and any component which is resistant to devitrification can be improved by lowering the liquidus temperature of the glass.

On the other hand, when the content of the TiO ₂ component is 20.0% or less, devitrification due to excessive content of the TiO ₂ component can be reduced, and the decrease in transmittance of visible light (especially, a wavelength of 500 nm or less) of the glass can be suppressed. Therefore, the content of the TiO ₂ component is preferably an upper limit of 20.0%, more preferably an upper limit of 15.0%, still more preferably an upper limit of 12.0%, and still more preferably an upper limit of 10.0%.

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

The Nb ₂ O ₅ component can increase the refractive index of the glass and reduce the Abbe number when it contains more than 0%, and can improve the devitrification resistance by lowering the liquidus temperature of the glass.

On the other hand, when the content of the Nb ₂ O ₅ component is 10.0% or less, devitrification due to excessive content of the Nb ₂ O ₅ component can be reduced, and the penetration of visible light (especially, a wavelength of 500 nm or less) of the glass can be suppressed. The rate is reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably an upper limit of 10.0%, more preferably an upper limit of 8.0%, still more preferably an upper limit of 6.0%, and still more preferably an upper limit of 5.0%.

As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component which can reduce the coloring of the glass due to other high refractive index components and can increase the refractive index, lower the glass transition point, and improve the devitrification resistance of the glass when it contains more than 0%. Therefore, the content of the WO ₃ component is preferably more than 0%, more preferably more than 0.3%, still more preferably more than 0.5%, and still more preferably more than 1.0%.

On the other hand, by setting the content of the WO ₃ component to 20.0% or less, the color of the glass due to the WO ₃ component can be reduced, and the visible light transmittance can be improved. Therefore, the content of the WO ₃ component is preferably 20.0% or less, more preferably 17.0% or less, and further preferably less than 15.0%, and more preferably 13.0% or less.

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

The molar content of the TiO ₂ component, the WO ₃ component, and the Nb ₂ O ₅ component is preferably 1.0% or more and 30.0% or less.

In particular, by setting the molar amount to 1.0% or more, the required optical constant can be obtained even if the Ta ₂ O ₅ component or the like is reduced, so that an optical glass having desired optical characteristics can be produced at a lower cost. Therefore, the molar and (TiO ₂ + WO ₃ + Nb ₂ O ₅ ) are preferably at a lower limit of 1.0%, more preferably at a lower limit of 2.5%, and still more preferably at a lower limit of 5.0%.

On the other hand, when the molar amount is 30.0% or less, the increase in the liquidus temperature due to the excessive content of the components can be suppressed, so that the devitrification of the optical glass can be reduced. Therefore, the molar and (TiO ₂ + WO ₃ + Nb ₂ O ₅ ) are preferably an upper limit of 30.0%, more preferably an upper limit of 25.0%, and still more preferably an upper limit of 20.0%.

The ZnO component is an optional component which can lower the glass transition point and improve chemical durability when it contains more than 0%. Therefore, the content of the ZnO component is preferably set to exceed 0%. More preferably, it is 10.0% as a lower limit, further preferably 12.0% is a lower limit, further preferably 15.0% is a lower limit, further preferably 20.0% is a lower limit, and more preferably 24.0% is a lower limit. .

On the other hand, by setting the content of the ZnO component to 38.0% or less, the liquidus temperature can be lowered, and devitrification due to excessive decrease in the glass transition point can be reduced. Therefore, the content of the ZnO component is preferably an upper limit of 38.0%, more preferably an upper limit of 36.0%, and still more preferably an upper limit of 35.0%.

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

The ZrO ₂ component is an optional component which can increase the refractive index and Abbe number of the glass when the content exceeds 0%, and can improve the resistance to devitrification. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 0.5%, and still more preferably more than 0.8%.

On the other hand, by setting the content of the ZrO ₂ component to 10.0% or less, devitrification due to excessive content of the ZrO ₂ component can be reduced. Therefore, the content of the ZrO ₂ component is preferably an upper limit of 10.0%, more preferably an upper limit of 8.0%, and still more preferably an upper limit of 5.0%.

As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

When the SiO ₂ component is contained in an amount exceeding 0%, the viscosity of the molten glass can be increased, the color of the glass can be lowered, and the devitrification resistance can be improved. Therefore, the content of the SiO ₂ component is preferably a lower limit of more than 0%, more preferably a lower limit of 1.0%, still more preferably a lower limit of 3.0%, and still more preferably a lower limit of 4.0%.

On the other hand, when the content of the SiO ₂ component is 15.0% or less, the increase in the glass transition point can be suppressed, and the decrease in the refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably an upper limit of 15.0%, more preferably an upper limit of 12.0%, still more preferably an upper limit of 10.0%, and still more preferably an upper limit of 9.0%.

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 Li ₂ O component is an optional component which lowers the glass transition point when it contains more than 0%.

On the other hand, by setting the content of the Li ₂ O component to 8.0% or less, the liquid phase temperature of the glass can be lowered to reduce devitrification, and chemical durability can be improved. Therefore, the content of the Li ₂ O component is preferably 8.0% or less, more preferably less than 4.0%, still more preferably less than 2.0%, and still more preferably less than 1.0%.

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

When the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component are contained in an amount of more than 0%, the meltability of the glass can be improved, the glass transition point can be increased, and the devitrification resistance can be improved.

On the other hand, when the content of the Na ₂ O component is 15.0% or less, and/or the content of each of the K ₂ O component and the Cs ₂ O component is 10.0% or less, it is difficult to lower the refractive index of the glass and can be lowered. The glass is devitrified. Therefore, the content of the Na ₂ O component is preferably an upper limit of 15.0%, more preferably an upper limit of 10.0%, still more preferably an upper limit of 5.0%, and still more preferably an upper limit of 3.0%. Further, the content of the K ₂ O component and the Cs ₂ O component is preferably an upper limit of 10.0%, more preferably an upper limit of 5.0%, and still more preferably an upper limit of 3.0%.

As the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _{6 can be used.} , Cs ₂ CO ₃ , CsNO ₃ and the like as raw materials.

The sum (molar sum) of the Rn ₂ O component (wherein Rn is selected from one or more of the group consisting of Li, Na, and K) is preferably 20.0% or less. Thereby, it is difficult to lower the refractive index of the glass, and the devitrification of the glass can be reduced. Therefore, the molar content of the Rn ₂ O component is preferably 20.0%, more preferably 10.0%, more preferably 5.0%, and even more preferably 3.5%. Jia is limited to 1.7%.

The MgO component, the CaO component, the SrO component, and the BaO component are optional components which can adjust the refractive index, meltability, and devitrification resistance of the glass when the content exceeds 0%.

On the other hand, when the content of each of the MgO component, the CaO component, the SrO component, and the BaO component is 10.0% or less, the desired refractive index can be easily obtained, and the loss of the glass due to the excessive content of the components can be reduced. through. Therefore, MgO component, CaO component, SrO The content of each of the component and the BaO component is preferably an upper limit of 10.0%, more preferably an upper limit of 5.0%, and still more preferably an upper limit of 3.0%.

As the MgO component, the CaO component, the SrO component, and the BaO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr(NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba(NO ₃ ) ₂ , BaF _{2 ,} or the like can be used. As a raw material.

The sum (molar sum) of the content of the RO component (wherein R is selected from one or more of the group consisting of Mg, Ca, Sr, and Ba) is preferably 11.0% or less. Thereby, the desired high refractive index can be easily obtained. Therefore, the molar content of the RO component is preferably an upper limit of 11.0%, more preferably an upper limit of 5.0%, and still more preferably an upper limit of 3.0%.

The GeO ₂ component is an optional component which increases the refractive index of the glass and increases the resistance to devitrification when it contains more than 0%.

However, since the raw material price of GeO ₂ is high, if the content is high, the production cost becomes high, and therefore the effect of reducing the Gd ₂ O ₃ component or the Ta ₂ O ₅ component or the like is offset. Therefore, the content of the GeO ₂ component is preferably an upper limit of 10.0%, more preferably an upper limit of 5.0%, further preferably an upper limit of 3.0%, more preferably an upper limit of 1.0%, and particularly preferably 0.1. % is the upper limit. From the viewpoint of reducing the material cost, the GeO ₂ component may not be contained.

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

The P ₂ O ₅ component is an optional component which lowers the liquidus temperature of the glass and increases the resistance to devitrification when it is more than 0%.

On the other hand, by setting the content of the P ₂ O ₅ component to 10.0% or less, the chemical durability of the glass, particularly the water resistance, can be suppressed. Therefore, the content of the P ₂ O ₅ component is preferably an upper limit of 10.0%, more preferably an upper limit of 5.0%, and still more preferably an upper limit of 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 Bi ₂ O ₃ component is an optional component which can increase the refractive index and reduce the glass transition point when it contains more than 0%.

On the other hand, by setting the content of the Bi ₂ O ₃ component to 15.0% or less, the liquidus temperature of the glass can be lowered to improve the devitrification resistance. Therefore, the content of the Bi ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, and still more preferably less than 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 which can increase the refractive index and reduce the glass transition point when it contains more than 0%.

On the other hand, when the glass crucible or the portion in contact with the molten glass is a molten glass raw material in a molten bath formed of platinum, there is a problem that TeO ₂ may be alloyed with platinum. Therefore, the content of the TeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, and still more preferably less than 3.0%.

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

When the Al ₂ O ₃ component and the Ga ₂ O ₃ component are contained in an amount of more than 0%, the chemical durability of the glass can be improved and the devitrification resistance of the molten glass can be improved.

On the other hand, by setting each content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 15.0% or less, the liquidus temperature of the glass can be lowered to improve the devitrification resistance. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0%, more preferably 10.0%, more preferably 5.0%, and still more preferably 3.0. % is the upper limit.

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.

When the SnO ₂ component is contained in an amount of more than 0%, the oxidation of the molten glass can be lowered and clarified, and the visible light transmittance of the glass can be increased.

On the other hand, by setting the content of the SnO ₂ component to 1.0% or less, the coloring of the glass or the devitrification of the glass due to the reduction of the molten glass can be reduced. Further, since the alloying of the SnO ₂ component and the melting device (especially a noble metal such as Pt) can be reduced, the life of the melting device can be extended. Therefore, the content of the SnO ₂ component is preferably 1.0% or less, more preferably 0.5% or less, and still more preferably less than 0.1%.

As 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 which can defoam 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 an upper limit of 1.0%, more preferably an upper limit of 0.7%, and still more preferably an upper limit of 0.5%.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ or Na ₂ H ₂ Sb ₂ O ₇ can be used. 5H ₂ O or the like is used as a raw material.

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

The F component is an optional component which can increase the Abbe number of the glass and lower the glass transition point when the content exceeds 0%, and can improve the devitrification resistance.

However, when the content of the F component, that is, the total amount of the fluoride in which one or both of the oxides of one or more of the above-mentioned elements are replaced by F is more than 15.0%, the amount of volatilization of the F component increases, and thus It is difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass.

Therefore, the content of the component F is preferably an upper limit of 15.0%, more preferably an upper limit of 10.0%, and most preferably an upper limit of 5.0%.

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

<About ingredients that should not be included>

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

Other additions may be added as needed within the scope of the characteristics of the glass of the invention of the present invention. Minute. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo has a small amount even separately. When it is contained or contained in a small amount in a composite form, the glass is also colored and has an absorption property for a specific wavelength of the visible region. Therefore, it is preferably substantially not contained in the optical glass having a wavelength of the visible region.

Further, since a lead compound such as PbO or an arsenic compound such as As ₂ O ₃ is a component having a high environmental load, it is preferably substantially not contained, that is, the above components are not contained except for unavoidable mixing.

Further, each of Th, Cd, Tl, Os, Be, and Se has a tendency to suppress its use as a harmful chemical substance in recent years, and it is necessary to adopt an environment not only in the manufacturing steps of glass but also in the processing steps and after processing. Countermeasures. Therefore, when it is important to pay attention to the influence of the environment, it is preferable that it does not substantially contain such.

The glass composition of the present invention has a composition in terms of mol% of the total mass of the glass in terms of oxide composition, and therefore is not directly expressed as % by mass, and is present in the present invention to satisfy the requirements. The composition represented by the mass % of each component in the glass composition of each characteristic is approximately the following value in terms of an oxide conversion composition.

B ₂ O ₃ component 5.0 to 30.0% by mass, La ₂ O ₃ component 10.0 to 60.0% by mass, and Y ₂ O ₃ component 0 to 40.0% by mass

Gd ₂ O ₃ component 0~30.0% by mass

Yb ₂ O ₃ composition 0~20.0% by mass

Lu ₂ O ₃ composition 0~20.0% by mass

Ta ₂ O ₅ component 0~30.0% by mass

TiO ₂ component 0~15.0% by mass

Nb ₂ O ₅ component 0~20.0% by mass

WO ₃ 0 to 40.0% by mass of the component

ZnO composition 0~25.0% by mass

ZrO ₂ component 0~10.0% by mass

SiO ₂ component 0~8.0% by mass

Li ₂ O composition 0~2.0% by mass

Na ₂ O composition 0~10.0% by mass

K ₂ O composition 0~8.0% by mass

Cs ₂ O composition 0~15.0% by mass

MgO composition 0~3.0% by mass

CaO composition 0~5.0% by mass

SrO composition 0~8.0% by mass

BaO composition 0~10.0% by mass

GeO ₂ component 0~12.0% by mass

P ₂ O ₅ component 0~10.0% by mass

Bi ₂ O ₃ composition 0~40.0% by mass

TeO ₂ component 0~15.0% by mass

Al ₂ O ₃ component 0~12.0% by mass

Ga ₂ O ₃ component 0~20.0% by mass

Sb ₂ O ₃ composition 0~3.0% by mass

And a total amount of fluoride in some or all of the oxides of one or more of the above elements, in terms of F, 0 to 3.0% by mass

In particular, the composition represented by the mass % of each component of the first optical glass is approximately the following value in terms of oxide conversion composition.

B ₂ O ₃ component 5.0 to 30.0% by mass, La ₂ O ₃ component 10.0 to 60.0% by mass, and Y ₂ O ₃ component 0 to 20.0% by mass

Gd ₂ O ₃ component 0~3.0% by mass

Yb ₂ O ₃ composition 0~20.0% by mass

Lu ₂ O ₃ composition 0~20.0% by mass

Ta ₂ O ₅ component 0~4.0% by mass

TiO ₂ component 0~15.0% by mass

Nb ₂ O ₅ component 0~20.0% by mass

WO ₃ 0 to 40.0% by mass of the component

ZnO composition 0~25.0% by mass

ZrO ₂ component 0~10.0% by mass

SiO ₂ component 0~8.0% by mass

Li ₂ O composition 0~2.0% by mass

Na ₂ O composition 0~10.0% by mass

K ₂ O composition 0~8.0% by mass

Cs ₂ O composition 0~15.0% by mass

MgO composition 0~3.0% by mass

CaO composition 0~5.0% by mass

SrO composition 0~8.0% by mass

BaO composition 0~10.0% by mass

GeO ₂ component 0~12.0% by mass

P ₂ O ₅ component 0~10.0% by mass

Bi ₂ O ₃ composition 0~40.0% by mass

TeO ₂ component 0~15.0% by mass

Al ₂ O ₃ component 0~12.0% by mass

Ga ₂ O ₃ component 0~20.0% by mass

Sb ₂ O ₃ composition 0~3.0% by mass

And a part or all of one or more of the above elements The total amount of fluoride substituted in F is 0~3.0% by mass

On the other hand, the composition represented by the mass % of each component of the second optical glass is approximately the following value in terms of oxide conversion composition.

B ₂ O ₃ component 5.0 to 30.0% by mass, La ₂ O ₃ component 10.0 to 60.0% by mass, and Y ₂ O ₃ component exceeding 0% by mass to 40.0% by mass

And Gd ₂ O ₃ component 0~30.0% by mass

Yb ₂ O ₃ composition 0~20.0% by mass

Lu ₂ O ₃ composition 0~20.0% by mass

Ta ₂ O ₅ component 0~30.0% by mass

TiO ₂ component 0~15.0% by mass

Nb ₂ O ₅ component 0~20.0% by mass

WO ₃ 0 to 40.0% by mass of the component

ZnO composition 0~25.0% by mass

ZrO ₂ component 0~10.0% by mass

SiO ₂ component 0~8.0% by mass

Li ₂ O composition 0~2.0% by mass

Na ₂ O composition 0~10.0% by mass

K ₂ O composition 0~8.0% by mass

Cs ₂ O composition 0~15.0% by mass

MgO composition 0~3.0% by mass

CaO composition 0~5.0% by mass

SrO composition 0~8.0% by mass

BaO composition 0~10.0% by mass

GeO ₂ component 0~12.0% by mass

P ₂ O ₅ component 0~10.0% by mass

Bi ₂ O ₃ composition 0~40.0% by mass

TeO ₂ component 0~15.0% by mass

Al ₂ O ₃ component 0~12.0% by mass

Ga ₂ O ₃ component 0~20.0% by mass

Sb ₂ O ₃ composition 0~3.0% by mass

And a total amount of fluoride in some or all of the oxides of one or more of the above elements, in terms of F, 0 to 3.0% by mass

[Production method]

The optical glass of the present invention is produced, for example, in the following manner. That is, the above-mentioned raw materials are uniformly mixed so that the respective components are within a specific content range, and the produced mixture is put into a platinum crucible, and the electric furnace is used at a temperature of 1100 to 1500 ° C according to the melting difficulty of the glass composition. The range is melted for 2 to 5 hours, homogenized by stirring, and then lowered to an appropriate temperature, and then cast into a mold to perform slow cooling, thereby producing.

[physical property]

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 1.80 as a lower limit, more preferably 1.81 as a lower limit, and still more preferably 1.82 as a lower limit. The refractive index (n _d ) is preferably an upper limit of 1.95, more preferably an upper limit of 1.93, and still more preferably an upper limit of 1.92. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably a lower limit of 30, more preferably a lower limit of 32, and still more preferably a lower limit of 33. The Abbe number (ν _d ) is preferably an upper limit of 45, more preferably an upper limit of 43, and further preferably an upper limit of 41.

By having such a high refractive index, even if the optical element is made thinner, a large amount of light can be obtained. Further, by having such a low dispersion, even if it is a single lens, the shift (chromatic aberration) of the focus due to the wavelength of light is reduced. In addition, by having such a low dispersion, for example, with light having a high dispersion (low Abbe number) When the components are combined, high imaging characteristics and the like can be achieved.

Therefore, the optical glass of the present invention is useful for optical design, and in particular, it is possible to achieve high imaging characteristics and the like, and it is possible to reduce the size of the optical system, thereby expanding the degree of freedom in optical design.

The optical glass of the present invention preferably has a high transmittance of visible light transmittance, particularly light on the short-wavelength side in visible light, whereby coloring is less.

In particular, the sample having a thickness of 10 mm of the optical glass of the present invention exhibits a shortest wavelength (λ ₇₀ ) having a spectral transmittance of 70%, preferably an upper limit of 450 nm, more preferably an upper limit of 420 nm, and further preferably an upper limit of 400 nm. .

Further, the sample having a thickness of 10 mm of the optical glass of the present invention exhibits a shortest wavelength (λ ₅ ) having a spectral transmittance of 5%, preferably an upper limit of 400 nm, more preferably an upper limit of 380 nm, and further preferably an upper limit of 360 nm. .

By the fact that the absorption end of the glass is located in the vicinity of the ultraviolet region to improve the transparency of the glass to visible light, the 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 higher resistance to devitrification and, more specifically, a lower liquidus temperature. That is, the liquidus temperature of the optical glass of the present invention is preferably an upper limit of 1100 ° C, more preferably an upper limit of 1080 ° C, and still more preferably an upper limit of 1060 ° C. Thereby, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is lowered, so that the devitrification at the time of forming the glass from the molten state can be reduced, and the optical characteristics of the optical element using the glass can be reduced. The impact. Moreover, since the range of the temperature at which the preform can be stably produced is widened, even if the melting temperature of the glass is lowered, the preform can be formed to suppress the energy consumed in the formation of the preform. 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 usually about 800 ° C or higher, specifically 850 ° C or higher. Specifically, it is 900 ° C or more. In addition, the term "liquid phase temperature" in this specification means Lower temperature: 30 cc glass-shaped glass sample was placed in a platinum crucible with a capacity of 50 ml, and it was completely melted at 1250 ° C, cooled to a specific temperature and kept for 12 hours, and taken out to the furnace. Immediately after cooling, the surface of the glass and the presence or absence of crystals in the glass were observed. At this time, the lowest temperature of crystallization was not observed. Here, the specific temperature at the time of cooling is a temperature of every 10 ° C between 1180 ° C and 800 ° C.

The optical glass of the present invention preferably has a glass transition point (Tg) of more than 580 ° C and 630 ° C or less.

In particular, by making the optical glass have a glass transition point of more than 580 ° C, even a high refractive index having a refractive index (n _d ) of 1.80 or more and 1.95 or less and an Abbe number (ν _d ) of 30 or more and 45 or less The low-dispersion optical glass also makes it difficult to crystallize the glass, so that devitrification at the time of glass production can be reduced, whereby a glass which is easily press-formed can be obtained. In particular, glass having a higher refractive index and a larger Abbe number tends to be more likely to crystallize the glass. Therefore, the effect obtained by setting the glass transition point to a temperature exceeding 580 ° C is remarkable. Therefore, the glass transition point of the optical glass of the present invention is preferably more than 580 ° C, more preferably more than 590 ° C, and still more preferably more than 600 ° C.

On the other hand, by making the optical glass have a glass transition point of 630 ° C or lower, the glass is softened at a lower temperature, so that the glass can be easily press-formed at a lower temperature. Moreover, the oxidation of the mold for press molding can be reduced, and the life of the mold can be extended. Therefore, the glass transition point of the optical glass of the present invention is preferably 630 ° C as the upper limit, more preferably 625 ° C as the upper limit, and still more preferably 620 ° C as the upper limit.

In addition, even if the glass transition point exceeds 580 ° C, the molding machine or the mold shown in Japanese Laid-Open Patent Publication No. 2007-186384 can be used to reduce the damage to the surface of the pressing mold, thereby improving the molding material. Durability, therefore, precision press forming of optical glass having a glass transition point of over 580 ° C is generally performed.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the optical glass of the present invention has a specific gravity of 5.50 [g/cm ³ ] or less. This reduces the quality of the optical component or the optical device in which it is used, thereby contributing to the weight reduction of the optical device. Therefore, the specific gravity of the optical glass of the present invention is preferably an upper limit of 5.50, more preferably an upper limit of 5.40, and still more preferably an upper limit of 5.30. Further, the specific gravity of the optical glass of the present invention is usually about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more.

The specific gravity of the optical glass of the present invention is measured based on the Japanese Optical Glass Industry Association specification JOGIS05-1975 "Method for Measuring the Specific Gravity of Optical Glass".

[Preformed materials and optical components]

The glass molded body can be produced from the produced optical glass by a method such as press molding such as reheat press molding or precision press molding. In other words, a preform for press molding can be produced from optical glass, and the preform can be subjected to reheat press forming, followed by polishing to form a glass molded body, or a preform or a borrowed product which can be produced by polishing. The preform formed by a known floating molding or the like is subjected to precision press molding to produce a glass molded body. Furthermore, the method of producing a glass molded body is not limited to these methods.

As such, the optical glass of the present invention can be used in a variety of optical components and optical designs. In particular, it is preferable to form a preform from the optical glass of the present invention, and to perform reheating press molding or precision press molding using the preform to prepare an optical element such as a lens or a crucible. As a result, a preform having a large diameter can be formed. Therefore, it is possible to increase the size of the optical element and to realize high-definition and high-precision imaging characteristics and projection characteristics when used in an optical device such as a camera or a projector.

[Examples]

The composition of the examples (No. A1 to No. A75, No. B1 to No. B71) and the comparative example (No. a) of the present invention, and the refractive index (n _d ) and Abbe number of the glasses ( The results of ν _d ), glass transition point (Tg), liquid phase temperature, and spectral transmittance show 5%, 70% of wavelength (λ ₅ , λ ₇₀ ) and specific gravity are shown in Tables 1 to 20. Here, the examples (No. A1 to No. A75) are examples of the first optical glass, and the examples (No. B1 to No. B71) are examples of the second optical glass. Furthermore, the following examples are for illustrative purposes only and are not limited to such embodiments.

In the glass of the examples and comparative examples of the present invention, oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric compounds, etc., which are respectively equivalent to the raw materials of the respective components, are generally used for the optical glass. The purity raw materials are weighed and uniformly mixed in such a manner as to be a ratio of the compositions of the respective examples shown in the table, and then introduced into a platinum crucible, and the electric furnace is used at 1100 to 1500 ° C according to the melting difficulty of the glass composition. The temperature range is melted for 2 to 5 hours, and then homogenized by stirring, and then cast into a mold or the like to perform slow cooling.

Here, the refractive index (n _d ) and the Abbe number (ν _d ) of the glass of the examples and the comparative examples were measured based on the Japanese Optical Glass Industry Association specification JOGIS01-2003. Here, the refractive index (n _d ) and the Abbe number (ν _d ) were determined by measuring the glass obtained by setting the slow cooling rate to -25 ° C/hr.

Further, the glass transition points (Tg) of the glasses of the examples and the comparative examples were determined by measurement using a horizontal expansion measuring instrument. Here, the sample used for the measurement was Φ4.8 mm and the length was 50 to 55 mm, and the temperature increase rate was set to 4 ° C/min.

Moreover, the transmittance of the glass of the examples and the comparative examples was measured in accordance with the Japanese Optical Glass Industry Association specification JOGIS02. Furthermore, in the present invention, the presence or absence and degree of coloring of the glass are determined by measuring the transmittance of the glass. Specifically, for a counter-parallel polished product having a thickness of 10 ± 0.1 mm, λ ₅ (wavelength at a transmittance of 5%) and λ ₇₀ (at a transmittance of 70%) are obtained by measuring a light transmittance of 200 to 800 nm in accordance with JIS Z8722. The wavelength).

Further, in the liquid phase temperatures of the glasses of the examples and the comparative examples, a temperature of 30 cc of a glass frit-shaped glass sample was placed in a platinum crucible having a capacity of 50 ml, and the film was completely melted at 1,250 °C. The temperature was lowered to between 1180 ° C and 800 ° C at any temperature set at 10 ° C for 12 hours, and taken out to the outside of the furnace. Immediately after cooling, the glass surface and the glass were observed for crystals. At this time, the lowest temperature of the crystal was not found.

Further, the specific gravity of the glass of the examples and the comparative examples was measured based on the Japanese Optical Glass Industry Association specification JOGIS05-1975 "Method for Measuring the Specific Gravity of Optical Glass".

As shown in the table, the optical glass of the embodiment of the present invention can reduce the content of the Gd ₂ O ₃ component or the Ta ₂ O ₅ component having a high material cost, and thus can be obtained at a lower cost.

In particular, the optical glass of the embodiment (No. A1 to No. A75) of the present invention is less than 5.0% due to Mohr and (Gd ₂ O ₃ + Ta ₂ O ₅ ), and more specifically, it is less than 0.3%. It can be obtained cheaper.

Further, in particular, the optical glass of the embodiment (No. B1 to No. B71) of the present invention can reduce the material by containing more than 0% of the Y ₂ O ₃ component having a low material cost, more specifically 3.0% or more. The content of the higher cost Gd ₂ O ₃ component or Ta ₂ O ₅ component. In more detail, since the molar and (Gd ₂ O ₃ +Ta ₂ O ₅ ) can be reduced to less than 5.0%, and more specifically, less than 0.3%, the desired optical fiber can be obtained at a lower cost. Constant optical glass.

On the other hand, the glass of the comparative example does not contain a Y ₂ O ₃ component having a low material cost, and the molar and (Gd ₂ O ₃ + Ta ₂ O ₅ ) are 16.455% and contain a large amount of Gd ₂ O ₃ or Ta ₂ O ₅ . Therefore, the material cost becomes higher.

The glass transition point (Tg) of the optical glass of the embodiment of the present invention exceeds 580 ° C and is 630 ° C or less, more specifically 583 ° C or more and 630 ° C or less in a desired range. On the other hand, the glass transition point (Tg) of the glass of the comparative example exceeded 630 °C.

Further, the liquid glass temperature of the optical glass of the embodiment of the present invention is 1100 ° C or less and is within a desired range. On the other hand, the liquid phase temperature of the glass of the comparative example exceeded 1100 °C.

Therefore, it is apparent that the optical glass of the embodiment of the present invention does not use a G ₂ O ₃ component or Ta ₂ even in the case of containing a Y ₂ O ₃ component which is low in material cost in a component which contributes to high refractive index and high dispersion. In the case of a component having a relatively high material cost such as an O ₅ component, the optical glass having a lower glass transition point can be more degraded than that of the glass of the comparative example.

Further, in the optical glass of the embodiment of the present invention, λ ₇₀ (wavelength at a transmittance of 70%) is 450 nm or less, and more specifically 440 nm or less. Further, in the optical glass of the embodiment of the present invention, λ ₅ (wavelength at a transmittance of 5%) is 400 nm or less, and more specifically 370 nm or less. Therefore, it is clear that the optical glass of the embodiment of the present invention has a high transmittance at a visible short wavelength and is not easily colored.

Further, the refractive index (n _d ) of the optical glass of the embodiment of the present invention is 1.80 or more, more specifically 1.81 or more, and the refractive index (n _d ) is 1.95 or less, and more specifically 1.92 or less. So within the required range.

Further, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) of 30 or more, more specifically 33 or more, and the Abbe number (ν _d ) is 45 or less, and more specifically 43 Below, thus within the required range.

Further, the optical glass of the embodiment of the present invention has a specific gravity of 5.50 or less, and more specifically 5.21 or less. Therefore, it is clear that the optical glass of the embodiment of the present invention has a small specific gravity.

Therefore, it is clear that the refractive index (n _d ) and the Abbe number (ν _d ) of the optical glass of the embodiment of the present invention are within a desired range, and the transmittance at a short wavelength is high, and the devitrification resistance is exhibited. Higher, it is easy to perform press forming by softening by heating, and the specific gravity is small.

Further, the optical glass of the embodiment of the present invention is subjected to reheat press forming, followed by grinding and polishing to form a lens and a crucible. Further, the optical glass of the embodiment of the present invention is used to form a preform for precision press molding, and the preform for precision press molding is precisely press-formed into a shape of a lens and a crucible. In either case, the glass which is softened by heating does not cause problems such as opacification and devitrification, and thus can be stably processed into various lenses and shapes of enamel.

The present invention has been described in detail above with reference to the embodiments of the present invention, but it is understood that the present invention is intended to be illustrative only, and many modifications may be made without departing from the spirit and scope of the invention.

Claims (31)

An optical glass containing 10.0% or more and 50.0% or less of a B ₂ O ₃ component, 5.0% or more and 30.0% or less of a La ₂ O ₃ component, and a content of a Gd ₂ O ₃ component of less than 1.0% by mole %. The ear and (TiO ₂ + WO ₃ + Nb ₂ O ₅ ) are 1.0 to 11.067%, and have a refractive index (n _d ) of 1.80 or more, and have an Abbe number (ν _d ) of 30 or more and 45 or less. The optical glass of claim 1, wherein the content of the Y ₂ O ₃ component is 20.0% or less in terms of mol%. The optical glass of claim 1, which contains more than 0% and 20.0% or less of the Y ₂ O ₃ component in mole %. The optical glass of claim 1, wherein the content of the Y ₂ O ₃ component is 10.0% or less in terms of mol%. The optical glass of claim 1, wherein the Yb ₂ O ₃ component is 0 to 10.0% and the Lu ₂ O ₃ component is 0 to 10.0% in terms of mol%. The optical glass of claim 1, wherein the content of the Ta ₂ O ₅ component is 10.0% or less in terms of mol%. The optical glass of claim 1, wherein the molar and (Gd ₂ O ₃ + Yb ₂ O ₃ + Ta ₂ O ₅ ) are 10.0% or less. The optical glass of claim 1, wherein the molar and (Gd ₂ O ₃ + Ta ₂ O ₅ ) are less than 5.0%. The optical glass of claim 1, wherein the content of the Ta ₂ O ₅ component is less than 1.0% in terms of mol%. The optical glass of claim 1, wherein the molar ratio of the Ln ₂ O ₃ component (wherein Ln is selected from one or more of the group consisting of La, Gd, Y, Yb, and Lu) is 10.0% or more and 40.0 %the following. The optical glass of claim 1, which contains two or more of the above-mentioned Ln ₂ O ₃ components. The optical glass of claim 1, wherein the TiO ₂ component is 0 to 20.0% and the Nb ₂ O ₅ component is 0 to 10.0% in terms of mol%. The optical glass of claim 1, wherein the content of the WO ₃ component is 20.0% or less in terms of mol%. The optical glass of claim 1, which contains 1.0% or more and 20.0% or less of the WO ₃ component in terms of mol%. The optical glass of claim 1, which contains 10.0% or more and 38.0% or less of the ZnO component in terms of mol%. The optical glass of claim 1, wherein the content of the ZrO ₂ component is 10.0% or less in terms of mol%. The optical glass of claim 1, wherein the content of the SiO ₂ component is 15.0% or less in terms of mol%. The optical glass of claim 1, wherein the content of the Li ₂ O component is 8.0% or less in terms of mol%. The optical glass of claim 1, wherein the Na ₂ O component is 0 to 15.0%, the K ₂ O component is 0 to 10.0%, and the Cs ₂ O component is 0 to 10.0%. The optical glass of claim 1, wherein the molar ratio of the Rn ₂ O component (wherein Rn is selected from one or more of the group consisting of Li, Na, K, and Cs) is 20.0% or less. The optical glass of claim 1, wherein the MgO component is 0 to 10.0%, the CaO component is 0 to 10.0%, and the SrO component is 0 to 10.0%, The BaO component is 0 to 10.0%. The optical glass of claim 1, wherein the molar composition of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 11.0% or less. The optical glass of claim 1, wherein the GeO ₂ component is 0 to 10.0%, the P ₂ O ₅ component is 0 to 10.0%, the Bi ₂ O ₃ component is 0 to 15.0%, and the TeO ₂ component is 0 to 15.0%, Al ₂ O ₃ component is 0 to 15.0%, Ga ₂ O ₃ component is 0 to 15.0%, and Sb ₂ O ₃ component is 0 to 1.0%, and one or more of the above elements are used. The fluoride in part or in whole of the oxide is contained in an amount of from 0 to 15.0 mol% in terms of F. The optical glass of claim 1, which has a refractive index (n _d ) of 1.80 or more and 1.95 or less, and has an Abbe number (ν _d ) of 30 or more and 45 or less. The optical glass of claim 1, wherein the glass transition point (Tg) exceeds 580 ° C and is 630 ° C or less. The optical glass of claim 1, which has a liquidus temperature of 1100 ° C or less. A preformed material comprising the optical glass of any one of claims 1 to 26. An optical element produced by press-forming a preform of claim 27. An optical element comprising the optical glass according to any one of claims 1 to 26 as a base material. An optical device comprising the optical component of claim 28. An optical device comprising the optical component of claim 29.