TWI673245B - Optical glass, preforms and optical components - Google Patents

Abstract

The object of the present invention is to obtain a preformed body at a lower cost, the refractive index (n _d ) and the Abbe number (ν _d ) of the preformed body are within the required ranges, and the precision compression molding is easy, and Higher devitrification resistance.

The optical glass of the present invention is measured in mole%, and contains B ₂ O ₃ component of 35.0% or more and 65.0% or less, La ₂ O ₃ component of 5.0% or more and 30.0% or less, and Moore and (Gd ₂ O ₃ + Ta ₂ O ₅ ) Less than 7.0%, having a refractive index (n _d ) of 1.65 or more, and an Abbe number (ν _d ) of 42 or more and 60 or less.

Description

Optical glass, preforms and optical components

The invention relates to an optical glass, a pre-formed body material and an optical element.

In recent years, digitization or high-definition of devices using optical systems has been rapidly promoted, and is used in various optical devices such as digital cameras, video cameras, and other photographic devices, or image playback (projection) devices such as projectors and projection televisions. In order to reduce the number of lenses and optical elements used in the optical system, and to reduce the weight and size of the optical system as a whole, there is an increasing demand.

Among the optical glasses used to make optical elements, in particular, it is possible to reduce the weight and size of the entire optical system. It has a refractive index (n _d ) of 1.65 or more, an Abbe number (ν _d ) of 42 or more, and 60 or less. The demand for high-refractive-index, low-dispersion glass for precision compression molding is very large. As such a high-refractive-index low-dispersion glass, the glass composition represented by patent documents 1 and 2 is known.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-249337

[Patent Document 2] Japanese Patent Laid-Open No. 2003-201143

The lenses used in the optical system include spherical lenses and aspherical lenses. If aspheric lenses are used, the number of optical elements can be reduced. In addition, various optics other than lenses The device is also known to have a surface having a complicated shape. However, if an aspheric surface or a surface having a complicated shape is to be obtained in the previous grinding and grinding steps, a high cost and complicated operation steps are necessary. Therefore, the method of precision-molding the method of obtaining the shape of the optical element by directly pressing the preformed body obtained from the blank or the glass block using an ultra-precision processing mold to obtain the shape of the optical element is the current mainstream.

Furthermore, in addition to a method of precision-molding a preformed body, a method of grinding and grinding a glass formed body is also known. This glass forming system reheats a blank or a glass block formed of a glass material to make It is obtained by forming (reheating and pressing).

As a method for manufacturing a preformed body used for such precision compression molding or reheating and press forming, there are a method of directly manufacturing from a molten glass by a dropping method, or reheating, pressing, or grinding a glass block into a ball. A method of grinding and grinding a processed product obtained in a shape. In any of the methods, an optical element is obtained by forming a molten glass into a desired shape, and therefore, it is required to easily perform precision press molding, and it is difficult to cause devitrification of the formed glass.

In addition, in order to reduce the material cost of the optical glass, it is desirable that the raw material cost of each component constituting the optical glass is as low as possible. In addition, in order to reduce the manufacturing cost of optical glass, it is preferable that the melting property of the raw material is higher, that is, the material is melted at a lower temperature. However, it is difficult to say that the glass compositions described in Patent Documents 1 and 2 are those that sufficiently satisfy these various requirements.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to obtain a preform at a lower cost, the refractive index (n _d ) and the Abbe number (ν _d ) of the preform being in a desired range. It is easy to perform precision compression molding and has high devitrification resistance.

In order to solve the above-mentioned problems, the inventors have conducted intensive experiments and studies, and found that an optical glass can be obtained. The optical glass is a glass containing a B ₂ O ₃ component and a La ₂ O ₃ component. The refractive index (n _d ) and Abbe number (ν _d ) are within the required range, and the content of Gd ₂ O ₃ component and Ta ₂ O ₅ component with high material cost is reduced, and it is not easy to cause during glass production and pressure forming Devitrification, thus completing the present invention.

Specifically, the present invention provides the following.

(1) An optical glass comprising, in mole%, a B ₂ O ₃ component of 35.0% or more and 65.0% or less, a La ₂ O ₃ component of 5.0% or more and 30.0% or less, and Moore and (Gd ₂ O ₃ + Ta ₂ O ₅ ) is less than 7.0%, has a refractive index (n _d ) of 1.65 or more, and has an Abbe number (ν _d ) of 42 or more and 60 or less.

(2) The optical glass according to (1), which has a refractive index (n _d ) of 1.70 or more.

(3) The optical glass according to (1), which contains Mo ₂ %, La ₂ O ₃ component of 8.0% or more and 30.0% or less, and has an Abbe number (ν _d ) of 45 or more and 60 or less.

(4) The optical glass according to any one of (1) to (3), wherein the Gd ₂ O ₃ component is 0 to less than 7.0% and the Ta ₂ O ₅ component is 0 to less than 5.0 in mole%. %.

(5) The optical glass according to any one of (1) to (4), wherein the Y ₂ O ₃ component is 0 to 15.0% and the Yb ₂ O ₃ component is 0 to 10.0% in mole%.

(6) The optical glass according to any one of (1) to (5), wherein the Ln ₂ O ₃ component (wherein, Ln is one selected from the group consisting of La, Gd, Y, Yb, and Lu The Mohr sum is 10.0% or more and 40.0% or less.

(7) The optical glass according to any one of (1) to (6), wherein the molar ratio Y ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ ) is more than 0 and less than 1.00.

(8) The optical glass according to any one of (1) to (7), wherein the content of the SiO ₂ component is 15.0% or less in mole%.

(9) The optical glass according to any one of (1) to (8), wherein the content of the ZrO ₂ component is 10.0% or less in mole%.

(10) The optical glass according to any one of (1) to (9), which contains a ZnO component in an amount of more than 0% to 40.0% in mol%.

(11) The optical glass according to any one of (1) to (10), in which the ZnO component is 5.0% or more and 40.0% or less in terms of mole%.

(12) The optical glass according to any one of (1) to (11), wherein the Nb ₂ O ₅ component is 0 to 10.0%, the WO ₃ component is 0 to 10.0%, and the Bi ₂ O ₃ The composition is 0 ~ 15.0%.

(13) The optical glass according to any one of (1) to (12), wherein Mohr and Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ are 15.0% or less.

(14) The optical glass according to any one of (1) to (13), wherein in terms of mole%, the Li ₂ O component is 0 to 10.0%, the Na ₂ O component is 0 to 15.0%, and the K ₂ O component It is 0 ~ 10.0%.

(15) The optical glass according to any one of (1) to (14), wherein Mohr and (ZnO + 2 × Li ₂ O) are 5.0% or more and 45.0% or less.

(16) The optical glass according to any one of (1) to (15), wherein the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) The sum is 20.0% or less.

(17) The optical glass according to any one of (1) to (16), wherein the MgO component is 0 to 10.0%, the CaO component is 0 to 40.0%, the SrO component is 0 to 30.0%, The BaO composition is 0 to 30.0%.

(18) The optical glass according to any one of (1) to (17), wherein the MgO component is 0 to 10.0%, the CaO component is 0 to 10.0%, the SrO component is 0 to 10.0%, The BaO composition is 0 to 10.0%.

(19) The optical glass according to any one of (1) to (18), wherein the RO component (wherein, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) The sum is 50.0% or less.

(20) The optical glass according to any one of (1) to (19), wherein the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) The sum is below 10.0%.

(21) The optical glass according to any one of (1) to (20), wherein the P ₂ O ₅ component is 0 to 10.0%, the GeO ₂ component is 0 to 10.0%, and Al ₂ O ₃ The composition is 0 to 15.0%, the Ga ₂ O ₃ composition is 0 to 15.0%, the TiO ₂ composition is 0 to 20.0%, the TeO ₂ composition is 0 to 15.0%, the SnO ₂ composition is 0 to 3.0%, and the Sb ₂ O ₃ composition The content of F is 0 to 1.0%, and the content of F, which is partially or completely substituted by one or more of the oxides of each of the metal elements, is 0 to 15.0 mole%.

(22) The optical glass according to any one of (1) to (21), which has a refractive index (n _d ) of 1.70 to 1.85 and an Abbe number (ν _d ) of 42 to 55.

(23) The optical glass according to any one of (1) to (22), which has a refractive index (n _d ) of 1.65 or more and 1.80 or less, and an Abbe number (ν _d ) of 50 or more and 60 or less.

(24) The optical glass according to any one of (1) to (23), which has a liquidus temperature of 1100 ° C or lower.

(25) A preformed body comprising the optical glass according to any one of (1) to (24).

(26) An optical element which is formed by press-molding a preformed body as in (25) Production.

(27) An optical element using the optical glass according to any one of (1) to (24) as a base material.

(28) An optical device provided with an optical element such as (26) or (27).

According to the present invention, a preformed body material can be obtained at a lower cost, the refractive index (n _d ) and the Abbe number (ν _d ) of the preformed body material are within a desired range, and precision compression molding is easy, and Higher devitrification resistance.

The optical glass of the present invention is measured in mole%, and contains B ₂ O ₃ component of 35.0% or more and 65.0% or less, La ₂ O ₃ component of 5.0% or more and 30.0% or less, and Moore and (Gd ₂ O ₃ + Ta ₂ O ₅ ) Less than 7.0%, having a refractive index (n _d ) of 1.65 or more, and an Abbe number (ν _d ) of 42 or more and 60 or less.

In particular, the first optical glass contains B ₂ O ₃ components in an amount of 35.0% or more and 65.0% or less, and La ₂ O ₃ components in an amount of 5.0% or more and 30.0% or less. The moles and (Gd ₂ O ₃ + Ta ₂ O ₅ ) is less than 7.0%, has a refractive index (n _d ) of 1.70 or more, and has an Abbe number (ν _d ) of 42 or more and 60 or less.

In addition, the second optical glass contains B ₂ O ₃ component in an amount of 35.0% or more and 65.0% or less in terms of Mohr%, La ₂ O ₃ component in an amount of 8.0% or more and 30.0% or less, and Moore and (Gd ₂ O ₃ + Ta ₂ O ₅ ) is less than 7.0%, has a refractive index (n _d ) of 1.65 or more, and has an Abbe number (ν _d ) of 45 or more and 60 or less.

Abbe with a refractive index (n _d ) of 1.65 or more (or 1.70 or more) and 42 or more and 60 or less (or 45 or more and 60 or less) by using the B ₂ O ₃ and La ₂ O ₃ components as a basis. (Ν _d ), and the liquidus temperature tends to be low. In addition, the inventors of the present invention have found that in glass having a refractive index (n _d ) of 1.65 or more (or 1.70 or more) and an Abbe number (ν _d ) of 42 or more and 60 or less (or 45 or more and 60 or less), Reduce the content of Gd ₂ O ₃ and Ta ₂ O ₅ components with high material cost, and reduce devitrification during glass production and press forming.

Therefore, an optical glass capable of obtaining a preformed body can be obtained at a low price, and the refractive index (n _d ) and Abbe number (ν _d ) of the preformed body are within a desired range, and it is easy to perform precision molding. Shaped and high devitrification resistance.

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

[Glass composition]

Hereinafter, the composition range of each component which comprises the optical glass of this invention is described. In this specification, when there is no special explanation in advance, the content of each component is expressed in mole% with respect to the total glass mass of the total oxide conversion composition. Here, the "oxide conversion composition" refers to the case where the oxide, the complex salt, and the metal fluoride used as the raw material of the glass constituent of the present invention are all decomposed during melting and changed to an oxide. The total mass of the oxide is 100 mol%, and the composition of each component contained in the glass is described.

<About essential ingredients and optional ingredients>

In the optical glass of the present invention containing a relatively large amount of rare earth oxides, the B ₂ O ₃ component is a component necessary for glass-forming oxides. In particular, by setting the content of the B ₂ O ₃ component to 35.0% 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 35.0% as the lower limit, more preferably 37.0% as the lower limit, still more preferably 38.0% as the lower limit, and even more preferably 40.0% as the lower limit. It is more preferable to set 45.0% as the lower limit, and it is more preferable to set 47.0% as the lower limit.

On the other hand, by setting the content of the B ₂ O ₃ component to 65.0% 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 65.0% as the upper limit, more preferably 62.0% as the upper limit, still more preferably 60.0% as the upper limit, and even more preferably 57.0% as the upper limit. It is more preferable to set 54.0% as the upper limit.

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

The La ₂ O ₃ component is an essential component that increases the refractive index of glass and increases the Abbe number of glass. Therefore, the content of the La ₂ O ₃ component is preferably 5.0% as the lower limit, more preferably 8.0% as the lower limit, even more preferably 10.0% as the lower limit, and even more preferably 12.0% as the lower limit. It is more preferable to set 13.0% as the lower limit.

On the other hand, devitrification can be reduced by improving the stability of the glass by setting the content of the La ₂ O ₃ component to 30.0% or less. Therefore, the content of the La ₂ O ₃ component relative to the total mass of the glass in terms of oxide conversion is preferably 30.0% as the upper limit, more preferably 20.0% as the upper limit, and even more preferably 18.0% as the upper limit. It is more preferable to set 16.0% as the upper limit.

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 total amount of the Gd ₂ O ₃ component and the Ta ₂ O ₅ component is preferably less than 7.0%. As a result, the content of these expensive components is reduced, so the material cost of glass can be suppressed. Therefore, Mohr and (Gd ₂ O ₃ + Ta ₂ O ₅ ) are preferably set to less than 7.0%, more preferably set to less than 4.0%, even more preferably set to less than 1.0%, and even more preferably It is set to less than 0.5%.

The Gd ₂ O ₃ component is an arbitrary component that can increase the refractive index of glass and increase the Abbe number when the content of Gd ₂ O ₃ exceeds 0%.

On the other hand, by setting the Gd ₂ O ₃ component, which is particularly expensive among the rare earth elements, to less than 7.0%, the material cost of the glass can be reduced, so that optical glass can be manufactured at a lower cost. In addition, it is possible to suppress an increase in the Abbe number of the glass more than necessary. Therefore, the contents of the Gd ₂ O ₃ components are preferably set to less than 7.0%, more preferably set to less than 5.0%, even more preferably set to less than 1.0%, and even more preferably set to less than 0.3. %, More preferably 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 Ta ₂ O ₅ component is an optional component that can increase the refractive index of glass and increase the devitrification resistance when the content of Ta ₂ O ₅ exceeds 0%.

On the other hand, by setting the expensive Ta ₂ O ₅ component to less than 5.0%, the material cost of glass can be reduced, so that optical glass can be produced at a lower cost. In addition, as a result, the melting temperature of the raw material is lowered, and the energy required for the melting of the raw material is reduced, so the manufacturing cost of the optical glass can also be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably less than 5.0%, more preferably less than 2.0%, even more preferably less than 1.0%, and even more preferably less than 0.3%. It is more preferable to set it to less than 0.1%.

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

The Y ₂ O ₃ component is an essential component that maintains a high refractive index and a high Abbe number by containing more than 0%, can suppress the material cost of the glass, and can reduce the specific gravity of the glass compared to other rare earth components. Therefore, the content of the Y ₂ O ₃ component is preferably set to exceed 0%, more preferably 0.5% is set as the lower limit, more preferably 1.0% is set as the lower limit, and even more preferably 1.7% is set as the lower limit. It is preferable to set 2.0% as the lower limit, more preferably 2.4% as the lower limit, still more preferably 3.0% as the lower limit, and even more preferably 3.1% as the lower limit.

On the other hand, when the content of the Y ₂ O ₃ component is set to 15.0% 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 15.0% as the upper limit, more preferably 10.0% as the upper limit, still more preferably 8.0% as the upper limit, and even more preferably 6.5% as the upper limit. It is more preferable to set 6.0% as the upper limit.

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

The Yb ₂ O ₃ component is an arbitrary component that can increase the refractive index of glass and increase the Abbe number when the content of Yb ₂ O ₃ is more than 0%.

On the other hand, by setting the content of the Yb ₂ O ₃ component to 10.0% or less, the material cost of the glass can be reduced, so that optical glass can be produced at a lower cost. In addition, the devitrification resistance of glass can be improved by this. Therefore, the content of the Yb ₂ O ₃ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, still more preferably 3.0% as the upper limit, and even more preferably 1.0% as the upper limit. It is more preferable to set it to less than 0.3%. From the viewpoint of reducing the material cost, the Yb ₂ O ₃ component may not be contained.

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

The sum (molar sum) of the content of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, Yb, Lu) is preferably 10.0% or more and 40.0% the following.

In particular, by setting the sum to 10.0% or more, both the refractive index and the Abbe number of the glass are improved, so that a glass having the required refractive index and the Abbe number can be easily obtained. Therefore, the molar sum of the Ln ₂ O ₃ component is preferably 10.0% as the lower limit, more preferably 12.0% as the lower limit, even more preferably 13.0% as the lower limit, and even more preferably 14.0% as The lower limit is more preferably 15.5% as the lower limit, and further preferably 17.0% as the lower limit.

On the other hand, by setting the sum to 40.0% or less, the liquidus temperature of the glass becomes low, so that devitrification of the glass can be reduced. Therefore, the molar sum of the Ln ₂ O ₃ component is preferably 40.0% as the upper limit, more preferably 30.0% as the upper limit, still more preferably 25.0% as the upper limit, and even more preferably 22.0%. Is the upper limit.

The optical glass of the present invention preferably contains two or more kinds of the aforementioned components of Ln ₂ O ₃ . With this, the liquidus temperature of the glass is further lowered, so that a glass with higher devitrification resistance can be obtained. It is particularly preferable to contain two or more components including a La ₂ O ₃ component and a Y ₂ O ₃ component from the viewpoint that the liquidus temperature of the glass can be easily lowered and the inexpensive optical glass can be produced. Ln ₂ O ₃ composition.

The ratio of the content of the Y ₂ O ₃ component to the total amount of the La ₂ O ₃ component and the Gd ₂ O ₃ component is preferably more than 0 and less than 1.00.

In particular, by setting the ratio to more than 0, the material cost of the glass can be suppressed and the specific gravity of the glass can be reduced compared to other rare earth components. Therefore, the molar ratio Y ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ ) is preferably set to more than 0, more preferably 0.10 is set as the lower limit, and still more preferably 0.15 is set as the lower limit. It is preferable to set 0.21 as the lower limit, more preferably 0.24 as the lower limit, and even more preferably 0.25 as the lower limit.

On the other hand, by setting the ratio to less than 1.00, devitrification of the glass can be reduced and a high refractive index can be easily obtained. Therefore, the molar ratio Y ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ ) is preferably set to less than 1.00, more preferably set to less than 0.85, and even more preferably set to less than 0.75. It is preferably less than 0.65, more preferably less than 0.50, and even more preferably less than 0.45.

The SiO ₂ component is an optional component that can increase the viscosity of the molten glass, reduce the color of the glass, and improve the devitrification resistance when the content is more than 0%. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably 1.0% or more, still more preferably 1.0% or more, still more preferably 1.3% or more, and even more preferably It is 1.8% or more, more preferably 2.0% or more, more preferably 3.0% or more, and even more preferably 4.0% or more.

On the other hand, by setting the content of the SiO ₂ component to 15.0% or less, it is possible to suppress an increase in the glass transition point and a decrease in the refractive index. Therefore, the content of the SiO ₂ component is preferably 15.0% as the upper limit, more preferably 12.0% as the upper limit, still more preferably 10.0% as the upper limit, and still more preferably 8.5% as the upper limit. The upper limit is preferably 7.8%.

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.

A ZnO component is an arbitrary component which can reduce a glass transition point and improves chemical durability when it contains more than 0%. Therefore, the content of the ZnO component is preferably set to more than 0%, more preferably 0.3% is set as the lower limit, still more preferably 1.0% is set as the lower limit, and still more preferably 5.0% is set as the lower limit. To set 6.0% as the lower limit, it is more preferable to set 8.0% is set as a lower limit, further preferably 10.0% is set as a lower limit, further preferably 11.0% is set as a lower limit, still more preferably 17.0% is set as a lower limit, and still more preferably 20.8% is set as a lower limit.

On the other hand, by setting the content of the ZnO component to 40.0% or less, it is possible to suppress a decrease in the Abbe number, reduce the liquidus temperature, and reduce devitrification due to a reduction in the glass transition point that is more than necessary. . Therefore, the content of the ZnO component is preferably 40.0% as the upper limit, more preferably 35.0% as the upper limit, still more preferably 33.0% as the upper limit, and even more preferably 30.0% as the upper limit. It is preferable to set 26.0% as the upper limit, more preferably 25.0% as the upper limit, and even more preferably less than 20.0%.

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

A ZrO ₂ component is an arbitrary component which improves the refractive index and Abbe number of glass, and improves devitrification resistance when it contains more than 0%. Therefore, the content of the ZrO ₂ component may be more than 0%, more preferably more than 0.1%, and even more preferably more than 0.3%.

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 10.0% or less, more preferably 8.0% or less, further preferably 6.0% or less, further preferably 5.0% or less, and more preferably It is set to less than 4.0%.

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

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

On the other hand, by setting the content of the Nb ₂ O ₅ component to 10.0% or less, the devitrification caused by the excessive content of the Nb ₂ O ₅ component can be reduced, and the glass can be suppressed from visible light (especially a wavelength of 500 nm or less). ). Therefore, the content of the Nb ₂ O ₅ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

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

The WO ₃ component is an optional component that reduces the coloration of glass due to other high refractive index components and increases the refractive index when the content exceeds 0%, which can lower the glass transition point and improve the devitrification resistance of the glass.

On the other hand, by setting the content of the WO ₃ component to 10.0% or less, the coloration of the glass due to the WO ₃ component can be reduced to increase the visible light transmittance. Therefore, the content of the WO ₃ component is preferably 10.0% as the upper limit, more preferably 7.0% as the upper limit, still more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

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

The Bi ₂ O ₃ component is an arbitrary component that can increase the refractive index and reduce the glass transition point when the content of Bi ₂ O ₃ exceeds 0%.

On the other hand, the devitrification resistance can be improved by lowering the liquidus temperature of the glass by setting the content of the Bi ₂ O ₃ component to 15.0% or less. Therefore, the content of the Bi ₂ O ₃ component is preferably 15.0% as the upper limit, more preferably less than 10.0%, even more preferably less than 5.0%, and even 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 molar sum of the Ta ₂ O ₅ component, the Bi ₂ O ₃ component, the WO ₃ component, and the Nb ₂ O ₅ component is preferably 15.0% or less. This can suppress the decrease in the Abbe number, so that it is possible to easily obtain a desired optical constant set in the present invention. Therefore, Mohr and (Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ) are preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0. % Is set to the upper limit, more preferably 1.0%, still more preferably 0.7%, still more preferably 0.5%, and even more preferably 0.3%.

The Li ₂ O component is an arbitrary component that can lower the glass transition point when the Li ₂ O component is contained in an amount exceeding 0%.

On the other hand, by setting the content of the Li ₂ O component to 10.0% or less, the liquidus temperature of the glass can be lowered and devitrification can be reduced, thereby improving chemical durability. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably 7.0%, still more preferably 5.0% or less, still more preferably 3.0% or less, and even more preferably It is less than 1.0%.

As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO _3, or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are arbitrary components that can improve the melting property of the glass, reduce the glass transition point, and improve the devitrification resistance when the content exceeds 0%.

On the other hand, when the content of the Na ₂ O component is set to 15.0% or less and / or the content of the K ₂ O component is set to 10.0% or less, it is difficult to reduce the refractive index of the glass and reduce the devitrification of the glass. Therefore, the content of the Na ₂ O component is preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, still more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit. The content of the K ₂ O component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

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

The total value of twice the content of the Li ₂ O component and the content of the ZnO component is preferably 5.0% or more and 45.0% or less.

By setting the total value to 5.0% or more, it is easier to obtain an optical glass having a high glass transition point and high chemical durability. Therefore, Mohr and (ZnO + 2 × Li ₂ O) preferably set 5.0% as the lower limit, more preferably 10.0% as the lower limit, even more preferably 15.0% as the lower limit, and even more preferably 19.0% is set as a lower limit, and further preferably 20.0% is set as a lower limit.

On the other hand, by setting the total value to 45.0% or less, it is difficult to reduce the refractive index and Abbe number of the glass. Therefore, Moore and (ZnO + 2 × Li ₂ O) preferably set 45.0% as the upper limit, more preferably 40.0% as the upper limit, even more preferably 35.0% as the upper limit, and even more preferably 30.0% is set as the upper limit, and further preferably 25.0% is set as the upper limit.

The sum (molar sum) of the content of the Rn ₂ O component (where Rn is one or more selected from the group consisting of Li, Na, and K) (molar sum) is preferably 20.0% or less. This makes it difficult to reduce the refractive index of the glass and reduces the devitrification of the glass. Therefore, the molar sum of the Rn ₂ O component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, even more preferably 10.0% as the upper limit, and even more preferably 7.0% as the upper limit. The upper limit is more preferably 6.0% as the upper limit, still more preferably 5.0% as the upper limit, still more preferably 3.5% as the upper limit, and still more preferably less than 2.0%.

The MgO component, the CaO component, the SrO component, and the BaO component are arbitrary components that can adjust the refractive index, meltability, and devitrification resistance of the glass when the content exceeds 0%. In particular, the CaO component, the SrO component, and the BaO component are components that can increase the Abbe number.

On the other hand, when the content of the MgO component is 10.0% or less, and / or the content of the CaO component is 40.0% or less, and / or the content of each of the SrO component and the BaO component is 30.0% or less, The required refractive index can be easily obtained and the devitrification of the glass due to the excessive content of these components can be reduced. Therefore, the content of the MgO component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit. The content of the CaO component is preferably 40.0% as the upper limit, more preferably 30.0% as the upper limit, still more preferably 20.0% as the upper limit, and even more preferably 15.0% as the upper limit. It is better to set 12.0% as the upper limit, more preferably 10.0% as the upper limit, still more preferably 8.0% as the upper limit, still more preferably 5.0% as the upper limit, and even more preferably 3.0%. Is the upper limit. The content of the SrO component and the BaO component is preferably 30.0% as the upper limit, more preferably 20.0% as the upper limit, still more preferably 15.0% as the upper limit, and even more preferably 10.0% as the upper limit. It is more preferable to set 8.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

MgO component, CaO component, SrO component and BaO component can use MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ etc. as raw materials .

The sum (molar sum) of the content of the RO component (where R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) (molar sum) is preferably 50.0% or less. Thereby, a desired high refractive index can be easily obtained. Therefore, the Mo content of the RO component is preferably 50.0% as the upper limit, more preferably In order to set 40.0% as the upper limit, it is more preferable to set 30.0% as the upper limit, further preferably 20.0% as the upper limit, still more preferably 12.0% as the upper limit, and even more preferably 10.0%. The upper limit is more preferably 8.0% as the upper limit, further preferably 5.0% as the upper limit, still more preferably 3.0% as the upper limit, and still more preferably less than 1.0%.

The P ₂ O ₅ component is an optional component that can increase the devitrification resistance by lowering the liquidus temperature of the glass when the content of P ₂ O ₅ exceeds 0%.

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

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

The GeO ₂ component is an optional component that can increase the refractive index of glass and increase the devitrification resistance when the content of GeO ₂ is more than 0%.

However, since the raw material price of GeO ₂ is high, if it is contained in a large amount, the production cost becomes high, thereby reducing the effects of reducing the Gd ₂ O ₃ component or the Ta ₂ O ₅ component. Therefore, the content of the GeO ₂ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, still more preferably 3.0% as the upper limit, and still more preferably 1.0% as the upper limit. The upper limit is preferably set to 0.1%. From the viewpoint of further 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 Al ₂ O ₃ component and the Ga ₂ O ₃ component are arbitrary components which can improve the chemical durability of the glass and improve the devitrification resistance of the molten glass when the content is more than 0%.

On the other hand, when the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is set to 15.0% or less, the liquidus temperature of the glass is lowered, and devitrification resistance can be improved. Therefore, the respective contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component are preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit. It is better to set 3.0% as 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 and the like can be used as raw materials.

The TiO ₂ component is an arbitrary component that can increase the refractive index and Abbe number of the glass when it contains more than 0%, and can improve the devitrification resistance by lowering the liquidus temperature of the glass.

On the other hand, the content of TiO ₂ by the component is set to 20.0% or less due to excessive decrease of the TiO ₂ component containing the devitrification due to, glass and can suppress visible light (wavelength, especially 500 nm or less) through the The reduction of the rate. Therefore, the content of the TiO ₂ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, still more preferably 12.0% as the upper limit, and still more preferably 10.0% as the upper limit. The upper limit is preferably 5.0%, and the upper limit is more preferably 1.0%.

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

The TeO ₂ component is an arbitrary component that can increase the refractive index and reduce the glass transition point when the content of the TeO ₂ component exceeds 0%.

On the other hand, TeO ₂ has a problem that when a glass raw material is melted in a crucible made of platinum or a melting tank formed of platinum in a portion in contact with molten glass, it can be alloyed to platinum. Therefore, the content of the TeO ₂ component is preferably 15.0% as the upper limit, more preferably 10.0% or less, still more preferably 5.0% or less, and even more preferably 3.0% or less.

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

The SnO ₂ component is an arbitrary component that reduces the oxidation of the molten glass when it contains more than 0% and clarifies the glass, and improves the visible light transmittance of the glass.

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

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

The Sb ₂ O ₃ component is an arbitrary component capable of defoaming the molten glass when the Sb ₂ O ₃ component is contained in an amount exceeding 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 is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% as the upper limit, more preferably 0.7% as the upper limit, and even more preferably 0.5% as the upper limit.

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

In addition, the component which clarifies and defoams glass is not limited to the above-mentioned Sb ₂ O ₃ component, and a known clarifier, defoamer, or a combination of these can be used in the field of glass production.

The F component is an arbitrary component that increases the Abbe number of the glass and lowers the glass transition point when the content exceeds 0%, and can improve devitrification resistance.

However, if the F component is contained, the volatilization amount of the F component from the molten glass increases, so it is difficult to obtain a stable optical constant, and it is difficult to obtain a homogeneous glass.

Therefore, the content of the F component, that is, the total amount of F which is a fluorine compound partially or completely substituted by one or two or more of the above-mentioned metal elements is preferably 15.0% as the upper limit, and more preferably 10.0% is set as the upper limit, more preferably 5.0% is set as the upper limit, and most preferably, it is not contained.

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

<Included ingredients>

Next, components that should not be contained in the optical glass of the present invention and components that are not satisfactory when contained are described.

As long as the characteristics of the glass of the present invention are not impaired, other components may be added as necessary. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, V, Each transition metal component such as Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, even if it contains a small amount of each of them individually or in combination, may cause the glass to be colored and have absorption at a specific wavelength in the visible region. Properties, it is particularly preferable that the optical glass is substantially free of the optical glass in which the wavelength in the visible region is used.

In addition, lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load. Therefore, they are preferably not substantially contained, that is, they are not contained except for inevitable mixing.

Furthermore, the components of Th, Cd, Tl, Os, Be, and Se have tended to be used as harmful chemical materials in recent years. Not only the glass manufacturing steps but also the processing steps and the processing after productization must require the environment. Measures. Therefore, when it is important to take environmental impact into consideration, it is preferable not to include these substances in substance.

Regarding the glass composition of the present invention, its composition is expressed in mole% with respect to the total mass of the glass in terms of the oxide conversion composition, so it is not directly stated as the mass%. The composition represented by the mass% of each component present in the glass composition is approximately the following values in terms of oxide conversion composition.

B ₂ O ₃ component 15.0 to 40.0 mass%, La ₂ O ₃ component 25.0 to 60.0 mass% Gd ₂ O ₃ component 0 to 20.0 mass% Ta ₂ O ₅ component 0 to 15.0 mass% Y ₂ O ₃ component 0 to 25.0 mass % Yb ₂ O ₃ component 0 to 25.0% by mass SiO ₂ component 0 to 10.0% by mass ZrO ₂ component 0 to 10.0% by mass ZnO component 0 to 25.0% by mass Nb ₂ O ₅ component 0 to 20.0% by mass WO ₃ component 0 to 20.0 Mass% Bi ₂ O ₃ component 0 to 40.0 mass% Li ₂ O component 0 to 3.0 mass% Na ₂ O component 0 to 10.0 mass% K ₂ O component 0 to 10.0 mass% MgO component 0 to 3.0 mass% CaO component 0 to 25.0 mass% SrO component 0 to 25.0 mass% BaO component 0 to 25.0 mass% P ₂ O ₅ component 0 to 10.0 mass% GeO ₂ component 0 to 10.0 mass% Al ₂ O ₃ component 0 to 10.0 mass% Ga ₂ O ₃ component 0 to 20.0% by mass TiO ₂ component 0 to 10.0% by mass TeO ₂ component 0 to 20.0% by mass SnO ₂ component 0 to 3.0% by mass Sb ₂ O ₃ component 0 to 3.0% by mass and as one of the above metal elements or Total amount of F of partially or totally substituted fluorides of one or more than two kinds of oxides 0 to 5.0% by mass

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

B ₂ O ₃ component 15.0 to 35.0 mass%, La ₂ O ₃ component 25.0 to 50.0 mass% Gd ₂ O ₃ component 0 to 20.0 mass% Ta ₂ O ₅ component 0 to 15.0 mass% Y ₂ O ₃ component 0 to 25.0 mass % Yb ₂ O ₃ component 0 to 25.0% by mass SiO ₂ component 0 to 8.0% by mass ZrO ₂ component 0 to 10.0% by mass ZnO component 0 to 25.0% by mass Nb ₂ O ₅ component 0 to 20.0% by mass WO ₃ component 0 to 15.0 Mass% Bi ₂ O ₃ component 0 to 35.0 mass% Li ₂ O component 0 to 3.0 mass% Na ₂ O component 0 to 8.0 mass% K ₂ O component 0 to 8.0 mass% MgO component 0 to 3.0 mass% CaO component 0 to 5.0% by mass SrO component 0 to 8.0% by mass BaO component 0 to 10.0% by mass P ₂ O ₅ component 0 to 10.0% by mass GeO ₂ component 0 to 8.0% by mass Al ₂ O ₃ component 0 to 10.0% by mass Ga ₂ O ₃ component 0 to 20.0% by mass TiO ₂ component 0 to 10.0% by mass TeO ₂ component 0 to 15.0% by mass SnO ₂ component 0 to 3.0% by mass Sb ₂ O ₃ component 0 to 3.0% by mass and as one of the above metal elements or Total amount of F of two or more oxides partially or totally substituted 0 to 5.0% by mass

In addition, the composition represented by the mass% of each component contained in the second optical glass is approximately the following value in terms of an oxide conversion composition.

B ₂ O ₃ component 20.0 to 40.0 mass%, La ₂ O ₃ component 30.0 to 60.0 mass%, and Gd ₂ O ₃ component 0 to 20.0 mass% Ta ₂ O ₅ component 0 to 15.0 mass% Y ₂ O ₃ component 0 to 25.0 mass% Yb ₂ O ₃ component 0 to 25.0 mass% SiO ₂ component 0 to 10.0 mass% ZrO ₂ component 0 to 10.0 mass% ZnO component 0 to 25.0 mass% Nb ₂ O ₅ component 0 to 20.0 mass% WO ₃ component 0 ~ 20.0 mass% Bi ₂ O ₃ component 0 to 40.0 mass% Li ₂ O component 0 to 3.0 mass% Na ₂ O component 0 to 10.0 mass% K ₂ O component 0 to 10.0 mass% MgO component 0 to 3.0 mass% CaO component 0 to 25.0% by mass SrO component 0 to 25.0% by mass BaO component 0 to 25.0% by mass P ₂ O ₅ component 0 to 10.0% by mass GeO ₂ component 0 to 10.0% by mass Al ₂ O ₃ component 0 to 10.0% by mass Ga ₂ O ₃ components 0 to 20.0% by mass TiO ₂ components 0 to 10.0% by mass TeO ₂ components 0 to 20.0% by mass SnO ₂ components 0 to 3.0% by mass Sb ₂ O ₃ components 0 to 3.0% by mass

And the total amount of F, which is a fluorine compound partially or completely substituted with one or two or more of the above-mentioned metal elements, 0 to 2.0% by mass

[Production method]

The optical glass of the present invention is produced, for example, as follows. That is, it is prepared by uniformly mixing the above-mentioned raw materials so that each component becomes within a specific content range, and putting the prepared mixture into a platinum crucible, and melting in an electric furnace at 1100 according to the ease of melting of the glass composition. It is melted in a temperature range of ~ 1500 ° C for 2 to 5 hours, stirred and homogenized, then lowered to an appropriate temperature, and then cast to a mold and slowly cooled.

[Physical properties]

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

In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.65 as the lower limit, more preferably 1.67 as the lower limit, still more preferably 1.69 as the lower limit, and even more preferably 1.70 as The lower limit is more preferably 1.71 as the lower limit, and still more preferably 1.73 as the lower limit. The refractive index (n _d ) is preferably 1.85 as the upper limit, more preferably 1.83 as the upper limit, still more preferably 1.82 as the upper limit, still more preferably 1.81 as the upper limit, and still more preferably 1.80 is set as the upper limit.

The Abbe number (ν _d ) of the optical glass of the present invention is preferably 42 as the lower limit, more preferably 43 as the lower limit, still more preferably 45 as the lower limit, and even more preferably 48. It is a lower limit, and it is more preferable to set 50 as a lower limit. The Abbe number (ν _d ) is preferably 60 as the upper limit, more preferably 58 as the upper limit, still more preferably 56 as the upper limit, and even more preferably 55 as the upper limit.

By having such a high refractive index, a large amount of light refraction can be obtained even if the optical element is thinned. Moreover, by having such a low dispersion, even if it is a single lens, the deviation (chromatic aberration) of the focus due to the wavelength of light is reduced. Furthermore, by having such a low dispersion, high imaging characteristics and the like can be achieved when combined with an optical element having a high dispersion (lower Abbe number), for example.

Therefore, the optical glass of the present invention is more useful in optical design, in particular, it can realize high imaging characteristics and the like and realize miniaturization 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, especially a light having a short wavelength side in the visible light, and thus has less coloration.

In particular, if the optical glass of the present invention is expressed by the transmittance of glass, the wavelength (λ ₈₀ ) showing a spectral transmittance of 80% in a sample with a thickness of 10 mm is preferably 500 nm as the upper limit, and more preferably 450 nm. Is the upper limit, more preferably the upper limit is 420 nm, and even more preferably the upper limit is 400 nm.

In addition, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in the sample with a thickness of 10 mm in the optical glass of the present invention is preferably 400 nm as the upper limit, more preferably 380 nm as the upper limit, and more preferably It is preferable to set 360 nm as the upper limit, more preferably 350 nm as the upper limit, still more preferably 340 nm as the upper limit, and even more preferably 310 nm as the upper limit.

With this, the absorption end of the glass becomes the ultraviolet region or its vicinity, and the transparency of the glass to visible light is improved. Therefore, the optical glass can be preferably used for an optical element that transmits light, such as a lens.

The optical glass of the present invention preferably has high devitrification resistance, and more specifically, preferably has a lower liquidus temperature. That is, the liquidus temperature of the optical glass of the present invention is preferably 1100 ° C as the upper limit, more preferably 1080 ° C as the upper limit, still more preferably 1060 ° C as the upper limit, and still more preferably 1050 ° C. Is the upper limit. Thereby, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is reduced, so the devitrification when the glass is formed from the molten state can be reduced, and the optical characteristics of the optical element using the glass can be reduced. Impact. In addition, the temperature range in which the preformed body can be stably produced is widened. Therefore, even if the melting temperature of the glass is reduced, the preformed body can be formed, and the energy consumed during the formation of the preformed body can be suppressed. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is Although it does not specifically limit, the liquidus temperature of the glass obtained by this invention is about 800 degreeC or more, specifically, 850 degreeC or more, and more specifically, 900 degreeC or more. In addition, the "liquid phase temperature" in this specification means that when a glass sample of 30cc in the shape of a glass crucible is placed in a platinum crucible with a capacity of 50ml, the platinum crucible is completely melted at 1250 ° C. When the temperature was lowered to a specific temperature and held for 12 hours, the glass surface and the presence of crystals in the glass were immediately observed after being taken out of the furnace and cooled, and the lowest temperature of the crystals was not observed. Here, the specific temperature at the time of temperature reduction is a temperature every 10 ° C between 1180 ° C and 800 ° C.

The optical glass of the present invention preferably has a glass transition point (Tg) exceeding 580 ° C and below 640 ° C.

Especially in the optical glass with high refractive index and low dispersion like the invention of the present case, since the optical glass has a glass transition point exceeding 580 ° C, it is not easy to cause crystallization, so the devitrification during press molding can be reduced, thereby making it possible to A glass suitable for press forming is obtained. In particular, the higher the refractive index and the larger the Abbe number of the glass, the more likely it is to cause crystallization of the glass. Therefore, the effect of setting the glass transition point to a temperature range exceeding 580 ° C is more obvious. Therefore, the glass transition point of the optical glass of the present invention is preferably set to exceed 580 ° C, more preferably set to exceed 585 ° C, still more preferably set to 590 ° C or higher, and even more preferably set to exceed 590 ° C.

On the other hand, since the optical glass has a glass transition point below 640 ° C, the glass is softened at a lower temperature, so the glass can be easily press-formed at a lower temperature. In addition, it is possible to reduce the oxidation of the mold used for pressure forming and realize a longer life of the mold. Therefore, the glass transition point of the optical glass of the present invention is preferably 640 ° C as the upper limit, more preferably 630 ° C as the upper limit, still more preferably 628 ° C as the upper limit, and even more preferably 625 ° C. Is the upper limit.

Furthermore, even if the glass transition point exceeds 580 ° C, the use of a molding machine or a mold such as that disclosed in Japanese Patent Laid-Open No. 2007-186384 can reduce the pressure on the mold for pressurization. Damage to the surface can improve the durability of the mold material. Therefore, precision press forming of optical glass with a glass transition point exceeding 580 ° C is usually performed.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 5.00 [g / cm ³ ] or less. As a result, the quality of the optical device or the optical device using the optical device is reduced, which can contribute to the weight reduction of the optical device. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00 as the upper limit, more preferably 4.80 as the upper limit, still more preferably 4.70 as the upper limit, still more preferably 4.60 as the upper limit, and even more preferably The upper limit is 4.40. In addition, the specific gravity of the optical glass of the present invention is generally 3.00 or more, more specifically 3.30 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 Standard JOGIS05-1975 "Method for Measuring Specific Gravity of Optical Glass".

[Preformed body and optical element]

A glass molded body can be produced from the manufactured optical glass using a method such as reheat press molding or precision press molding. That is, a preform for press molding can be produced from optical glass, and the preform can be reheated and pressure-molded, and then subjected to a grinding process to produce a glass formed body, or a preform produced by the grinding process, or A preform formed by a known suspension molding or the like is subjected to precision press molding to produce a glass formed body. In addition, the method of manufacturing a glass forming body is not limited to these methods.

As such, the optical glass of the present invention is useful for a variety of optical elements and optical designs. Among them, it is particularly preferable to form a preform from the optical glass of the present invention, and use the preform to perform reheat press molding, precision press molding, or the like to produce an optical element such as a lens or a cymbal. Thereby, a preform having a large diameter can be formed, so that the optical element can be increased in size, and when used in an optical device such as a camera or a projector, high-definition and high-precision imaging characteristics and projection characteristics can be realized.

[Example]

The composition of the examples (No.A1 to No.A74, No.B1 to No.B44), comparative example (No.A) and reference example (No.a) of the present invention, and the refractive index ( n _d ), Abbe number (ν _d ), glass transition point (Tg), liquidus temperature, and spectral transmittance show wavelengths of 5% and 80% (λ ₅ , λ ₈₀ ) and specific gravity results are shown in Table 1 ~ Table 17. In particular, the embodiments (No. A1 to No. A74) are also examples of the first optical glass, and the embodiments (No. B1 to No. B44) are also examples of the second optical glass. In addition, the following embodiments are always for the purpose of illustration, and are not limited to these embodiments.

The glasses of the examples, comparative examples, and reference examples of the present invention are selected from the equivalent oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds and the like. The purity raw material is used as the raw material of each component, weighed and uniformly mixed so as to become the ratio of the composition of each example shown in the table, and then put into a platinum crucible. The melting degree of the glass composition in the electric furnace is 1100 ~ After melting within a temperature range of 1500 ° C for 2 to 5 hours, the mixture is homogenized by stirring, and then cast into a mold, etc., and then slowly cooled to produce it.

Here, the refractive index (n _d ) and Abbe number (ν _d ) of the glass in the examples, comparative examples, and reference examples are measured based on the Japan Optical Glass Industry Standard JOGIS01-2003. Here, the refractive index (n _d ) and the Abbe number (ν _d ) are obtained by measuring a glass obtained by setting a slow cooling rate to -25 ° C./hr.

The glass transition point (Tg) of the glass of an Example, a comparative example, and a reference example was calculated | required by performing the measurement using the horizontal expansion measuring device. Here, the sample used in the measurement is used 4.8mm, 50 ~ 55mm in length, and set the heating rate to 4 ° C / min.

The transmittances of the glasses of the examples, comparative examples, and reference examples were measured in accordance with the standards of the Japan Optical Glass Industry Association JOGIS02. Furthermore, in the present invention, the presence or absence of the color of the glass is determined by measuring the transmittance of the glass. Specifically, according to JISZ8722, the parallel transmittance of a surface of 10 ± 0.1mm in thickness was measured at a spectral transmittance of 200 to 800 nm, and λ ₅ (wavelength at 5% transmission) and λ ₈₀ (wavelength at 80% transmission) ).

The liquidus temperature of the glass in the examples, comparative examples and reference examples is that when a 30cc glass-like glass sample is put into a platinum crucible in a 50ml platinum crucible, it becomes completely molten at 1250 ° C. Reduce the temperature to any temperature set between 1180 ° C and 800 ° C every 10 ° C and keep it for 12 hours. After taking it out of the furnace and cooling it, immediately observe the presence of crystals on the glass surface and in the glass. The lowest temperature for crystallization.

The specific gravity of the glass in the examples, comparative examples, and reference examples was measured based on the standard of the Japan Optical Glass Industry Association JOGIS05-1975 "method for measuring the specific gravity of optical glass".

As shown in the table, in the optical glass according to the embodiment of the present invention, Moire (Gd ₂ O ₃ + Ta ₂ O ₅ ) is less than 7.0%, so it can be obtained at a lower cost. On the other hand, in the glass of Comparative Example (No. A), Mohr (Gd ₂ O ₃ + Ta ₂ O ₅ ) was 8.353%, so the material cost was high.

The glass transition point (Tg) of the optical glass according to the embodiment of the present invention is more than 580 ° C. and 640 ° C. or less, more specifically, 590 ° C. or more and 638 ° C. or less, so that it is within a desired range. In particular, the glass transition point (Tg) of the first optical glass is more than 580 ° C and 630 ° C or less, and more specifically 590 ° C or more and 630 ° C or less. In addition, the glass transition points (Tg) of the optical glasses of the examples (Nos. B1 to B12, B16 to B18, and B21 to B44) of the present invention all exceeded 580 ° C and 630 ° C or lower. On the other hand, the glass transition point (Tg) of the glass of the comparative example (No. A) and the reference example (No. a) exceeded 630 ° C.

In addition, the liquidus temperature of the optical glass according to the embodiment of the present invention is all 1100 ° C. or lower, more specifically 1080 ° C. or lower, so that it is within a required range.

Therefore, it can be understood that even if the optical glass according to the embodiment of the present invention does not use a component having a high material cost such as a Gd ₂ O ₃ component or a Ta ₂ O ₅ component, it can reduce devitrification during glass production and press molding.

The λ ₈₀ (wavelength at 80% transmittance) of the optical glass according to the embodiment of the present invention is all 500 nm or less, and more specifically 450 nm or less. In particular, the λ ₈₀ of the second optical glass is 400 nm or less.

The λ ₅ (wavelength at 5% transmittance) of the optical glass according to the embodiment of the present invention is all 400 nm or less, and more specifically 340 nm or less. In particular, λ ₅ of the second optical glass is 300 nm or less.

Therefore, it can be understood that in the optical glass of the embodiment of the present invention, the transmittance in the visible short wavelength is high and it is not easy to be colored.

The refractive index (n _d ) of the optical glass according to the embodiment of the present invention is all 1.65 or more, and more specifically 1.69 or more, so that it is within a desired range. In particular, the refractive index (n _d ) of the first optical glass is 1.70 or more, and more specifically 1.73 or more. On the other hand, this refractive index (n _d ) is 1.85 or less, and more specifically, 1.80 or less.

The Abbe numbers (ν _d ) of the optical glass according to the embodiment of the present invention are all 42 or more, so that they are within a desired range. In particular, the Abbe number (ν _d ) of the second optical glass is 45 or more, and more specifically 50 or more.

On the other hand, the Abbe number (ν _d ) of the optical glass according to the embodiment of the present invention is 60 or less, more specifically, 56 or less, and it is also within the required range here. In particular, the Abbe number (ν _d ) of the first optical glass is 54 or less.

The specific gravity of the optical glass of the examples of the present invention is all 5.00 [g / cm ³ ] or less, and more specifically 4.60 [g / cm ³ ] or less. In particular, the specific gravity of the second optical glass is 4.30 [g / cm ³ ] or less. Therefore, it can be understood that the specific gravity of the optical glass of the embodiment of the present invention is relatively small.

Therefore, it can be understood that the refractive index (n _d ) and Abbe number (ν _d ) of the optical glass according to the embodiment of the present invention are within the required ranges, and it can be seen that the transmittance in the short wavelength is higher, and the devitrification resistance is better. High, easy to carry out pressure molding by heating and softening, and has a small specific gravity.

Furthermore, the optical glass according to the embodiment of the present invention is used for grinding and polishing after reheating and press forming, and is processed into the shape of a lens and a cymbal. In addition, the optical glass according to the embodiment of the present invention is used to form a preform for precision press molding, and the preform for precision press molding is precision press processed into the shape of a lens and a cymbal. In any case, there will be no problems such as milky whitening and devitrification in the glass after heating and softening, so that it can be processed into various lens and ray shapes in a stable manner.

In the above, the present invention has been described in detail for the purpose of illustration, but it is hoped that this embodiment is always for the purpose of illustration, and various modifications can be made by the industry without departing from the spirit and scope of the present invention.

Claims (28)

An optical glass, in terms of mole%, containing more than 35.0% and less than 65.0% of the B ₂ O ₃ component, more than 5.0% and less than 30.0% of the La ₂ O ₃ component, and a content of less than 6.0% of the ZrO ₂ component. And (Gd ₂ O ₃ + Ta ₂ O ₅ ) is less than 7.0%, has a refractive index (n _d ) of 1.65 or more, and has an Abbe number (ν _d ) of 42 or more and 60 or less. The optical glass of claim 1, which has a refractive index (n _d ) of 1.70 or more. For example, the optical glass of claim 1 contains La ₂ O ₃ component in an amount of 8.0% or more and 30.0% or less, and has an Abbe number (ν _d ) of 45 or more and 60 or less. For example, the optical glass of claim 1 has a Gd ₂ O ₃ composition of 0 to 7.0% and a Ta ₂ O ₅ composition of 0 to 5.0% in mole%. For example, the optical glass of claim 1, wherein in terms of mole%, the Y ₂ O ₃ component is 0 to 15.0%, and the Yb ₂ O ₃ component is 0 to 10.0%. For example, the optical glass of claim 1, wherein the molar sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) is 10.0% or more and 40.0% or less. For example, the optical glass of claim 1, wherein the molar ratio Y ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ ) is more than 0 and less than 1.00. For example, the optical glass of claim 1, wherein the content of the SiO ₂ component is 15.0% or less in mole%. For example, the optical glass of claim 1 contains a ZnO component in an amount of more than 0% and less than 40.0% in mole%. For example, the optical glass of claim 1 contains 5.0% to 40.0% of a ZnO component in terms of mole%. For example, the optical glass of claim 1, wherein in terms of mole%, the composition of Nb ₂ O ₅ is 0 to 10.0%, the composition of WO ₃ is 0 to 10.0%, and the composition of Bi ₂ O ₃ is 0 to 15.0%. For example, the optical glass of claim 1, wherein Mohr and Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ are 15.0% or less. For example, the optical glass of claim 1, wherein in terms of mole%, the Li ₂ O component is 0 to 10.0%, the Na ₂ O component is 0 to 15.0%, and the K ₂ O component is 0 to 10.0%. For example, the optical glass of claim 1, wherein Mohr and (ZnO + 2 × Li ₂ O) are 5.0% or more and 45.0% or less. For example, the optical glass of claim 1, wherein the molar sum of the Rn ₂ O component (wherein, Rn is one or more selected from the group consisting of Li, Na, and K) is 20.0% or less. For example, the optical glass of claim 1, wherein in terms of mole%, the MgO component is 0 to 10.0%, the CaO component is 0 to 40.0%, the SrO component is 0 to 30.0%, and the BaO component is 0 to 30.0%. For example, the optical glass of claim 1, wherein in terms of mole%, the MgO component is 0 to 10.0%, the CaO component is 0 to 10.0%, the SrO component is 0 to 10.0%, and the BaO component is 0 to 10.0%. For example, the optical glass of claim 1, wherein the Mo component of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 50.0% or less. For example, the optical glass of claim 1, wherein the molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 10.0% or less. For example, the optical glass of claim 1, wherein in terms of mole%, the composition of P ₂ O ₅ is 0 to 10.0%, the composition of GeO ₂ is 0 to 10.0%, the composition of Al ₂ O ₃ is 0 to 15.0%, and the content of Ga ₂ O ₃ The composition is 0 to 15.0%, the TiO ₂ composition is 0 to 20.0%, the TeO ₂ composition is 0 to 15.0%, the SnO ₂ composition is 0 to 3.0%, and the Sb ₂ O ₃ composition is 0 to 1.0%. The content of F in a partially or completely substituted one or more oxides of metal elements is 0 to 15.0 mol%. For example, the optical glass of claim 1 has a refractive index (n _d ) of 1.70 to 1.85 and an Abbe number (ν _d ) of 42 or more and 55 or less. For example, the optical glass of claim 1 has a refractive index (n _d ) of 1.65 or more and 1.80 or less, and an Abbe number (ν _d ) of 50 or more and 60 or less. The optical glass of claim 1, which has a liquidus temperature below 1100 ° C. A preformed body material comprising the optical glass according to any one of claims 1 to 23. An optical element manufactured by press-molding a preformed body as in claim 24. An optical element using the optical glass according to any one of claims 1 to 23 as a base material. An optical device including an optical element as claimed in claim 25. An optical device including an optical element as claimed in claim 26.