JP2015044724A - Optical glass, preform, and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain a preform material that can be easily subjected to precision mold press molding and has high devitrification resistance, while having a refractive index (n) and an Abbe number (ν) in desired ranges.SOLUTION: An optical glass is provided, which comprises a BOcomponent by 35.0% or more and 65.0% or less and a LaOcomponent by 5.0% or more and 30.0% or less, in terms of mol%, with a molar sum (GdO+TaO) of less than 7.0%, and has a refractive index (n) of 1.70 or more and an Abbe number (ν) of 42 or more and 60 or less.

Description

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

  In recent years, digitization and high definition of devices using optical systems have been rapidly progressing, and various optical devices such as photographing devices such as digital cameras and video cameras, and image reproduction (projection) devices such as projectors and projection televisions. In this field, there is an increasing demand to reduce the number of optical elements such as lenses and prisms used in the optical system, and to reduce the weight and size of the entire optical system.

Among optical glasses for producing optical elements, in particular, the optical system has a refractive index (n _d ) of 1.70 or more and an Abbe number of 42 or more and 60 or less (which can reduce the size of the entire optical system). There is a great demand for high refractive index, low dispersion glass capable of precision mold pressing with ν _d ). As such a high refractive index and low dispersion glass, glass compositions represented by Patent Documents 1 and 2 are known.

JP 2002-249337 A JP 2003-201143 A

  The lenses used in the optical system include a spherical lens and an aspheric lens. If an aspheric lens is used, the number of optical elements can be reduced. In addition, various optical elements other than lenses are known which have a complicatedly shaped surface. However, in order to obtain an aspherical surface or a complicatedly shaped surface by conventional grinding and polishing processes, a high-cost and complicated work process is required. Therefore, a method of obtaining a shape of an optical element by directly press-molding a preform material obtained from a gob or a glass block with an ultra-precision processed mold, that is, a method of precision mold press molding is currently mainstream.

  In addition to the method of precision mold press molding a preform material, a glass molded body obtained by reheating and molding (reheat press molding) a gob or glass block formed from a glass material is ground and polished. Methods are also known.

  As a manufacturing method of a preform material used for such precision mold press molding and reheat press molding, a method of directly manufacturing from a molten glass by a dropping method, a reheat press of a glass block, or a grinding process into a ball shape is obtained. There is a method of grinding and polishing processed products. In any method, in order to form a molten glass into a desired shape to obtain an optical element, it is required that precision mold press molding is easy and devitrification does not easily occur in the formed glass. .

  In addition, in order to reduce the material cost of the optical glass, it is desirable that the raw material costs of the components constituting the optical glass be as low as possible. Moreover, in order to reduce the manufacturing cost of optical glass, it is desired that the raw material has high meltability, that is, it is melted at a lower temperature. However, it is difficult to say that the glass compositions described in Patent Documents 1 and 2 sufficiently meet these requirements.

The present invention has been made in view of the above problems, and its object is to perform precision mold press molding while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges. It is to obtain a preform material that is easy to perform and has high devitrification resistance at a lower cost.

The present inventors have found that in order to solve the above problems, the results of extensive research, the glass contains B ₂ O ₃ component and La ₂ O ₃ component refractive index (n _d) and Abbe number ([nu _d ) is within the desired range, and an optical glass which is less likely to be devitrified during glass production and press molding while reducing the content of Gd ₂ O ₃ component and Ta ₂ O ₅ component, which are high in material cost. It has been found that it can be obtained, and the present invention has been completed.
Specifically, the present invention provides the following.

(1) in _mole%, B 2 _{O 3} component 65.0% 35.0% or more of the following, _La 2 _{O 3} containing component 30.0% 10.0% or more or less, the molar sum _(Gd 2 _{O 3} + Ta ₂ O ₅ ) is less than 7.0%, an optical glass having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 42 or more and 60 or less.

(2) In mol%,
Gd ₂ O ₃ component 0 to less than 7.0% Ta ₂ O ₅ component 0 to less than 5.0% optical glass according to (1).

(3) In mol%,
Y ₂ O ₃ component 0 to 15.0%
Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to (1) or (2).

(4) 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. The optical glass according to any one of (1) to (3).

(5) the molar ratio of _{Y 2 O 3 / (La 2} O 3 + Gd 2 O 3) is 0 or wherein the optical glass from less than ultra 1.00 (1) (4).

(6) The optical glass according to any one of (1) to (5), wherein the content of the SiO ₂ component is 15.0% or less in terms of mol%.

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

  (8) The optical glass according to any one of (1) to (7), which contains 5.0% to 40.0% of a ZnO component in mol%.

(9) In mol%,
Li ₂ O component 0 to 10.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 10.0%
The optical glass according to any one of (1) to (8).

(10) The optical glass according to any one of (1) to (9), wherein a molar sum (ZnO + 2 × Li ₂ O) is 5.0% or more and 45.0% or less.

(11) Any of (1) to (10), 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 The optical glass described.

(12) MgO component in mol% 0 to 10.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
The optical glass according to any one of (1) to (11).

  (13) The RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) has a molar sum of 10.0% or less, and any one of (1) to (12) The optical glass described.

(14) mole percent _P 2 _{O 5} component from 0 to 10.0%
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 15.0%
Ga ₂ O ₃ component from 0 to 15.0%
TiO ₂ component 0-20.0%
Nb ₂ O ₅ component 0 to 10.0%
WO ₃ components 0 to 10.0%
Bi ₂ O ₃ component 0 to 15.0%
TeO ₂ component 0-15.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-1.0%
And
Any one of (1) to (13), wherein the content of fluoride in which one or two or more oxides of each of the above metal elements are substituted with F is 0 to 15.0 mol% The optical glass described.

(15) The optical glass according to any one of (1) to (14), which has a refractive index (n _d ) of 1.70 to 1.85 and an Abbe number (ν _d ) of 42 to 55.

  (16) The optical glass according to any one of (1) to (15), which has a liquidus temperature of 1100 ° C. or lower.

  (17) A preform made of the optical glass according to any one of (1) to (16).

  (18) An optical element produced by press-molding the preform material according to (17).

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

  (20) An optical apparatus comprising the optical element according to (18) or (19).

According to the present invention, a preform material that is easy to perform precision mold press molding and has high devitrification resistance while having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range can be manufactured at a lower cost. Can get to.

The optical glass of the present invention contains, in mol%, a B ₂ O ₃ component of 35.0% to 65.0%, a La ₂ O ₃ component of 5.0% to 30.0%, 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. Based on the B ₂ O ₃ component and the La ₂ O ₃ component, while having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 42 to 60, the liquidus temperature Tends to be low. Further, the inventor of the present application uses a Gd ₂ O ₃ component and a Ta ₂ O ₅ component having high material costs in a glass having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 42 or more and 60 or less. It has been found that devitrification during glass production and press molding can be reduced while reducing the content of. Accordingly, an optical device capable of obtaining a preform material that is easy to perform precision mold press molding and has high devitrification resistance while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. Glass can be obtained inexpensively.

  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 implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In the present specification, unless otherwise specified, the content of each component is expressed in mol% with respect to the total amount of glass in the oxide conversion composition. Here, the “oxide equivalent composition” is based on the assumption that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides during melting. It is the composition which described each component contained in glass by making the total amount of substances of a production | generation oxide into 100 mol%.

<About essential and optional components>
The B ₂ O ₃ component is an essential component as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth 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 increased and the Abbe number of the glass can be increased. Therefore, the content of the B ₂ O ₃ component is preferably 35.0%, more preferably 37.0%, and still more preferably 38.0%.
On the other hand, by making the content of the B ₂ O ₃ component 65.0% or less, a larger refractive index can be easily obtained, and deterioration of chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 65.0%, more preferably 60.0%, further preferably 57.0%, and further preferably 54.0%.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The La ₂ O ₃ component is an essential component that increases the refractive index of the glass and increases the Abbe number of the glass. Therefore, the content of the La ₂ O ₃ component is preferably 5.0%, more preferably 8.0%, still more preferably 10.0%, and still more preferably 13.0%.
On the other hand, devitrification can be reduced by increasing 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 with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, still more preferably 18.0%, still more preferably 16. The upper limit is 0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The total amount of the Gd ₂ O ₃ component and the Ta ₂ O ₅ component is preferably less than 7.0%. Thereby, since content of these expensive components is reduced, the material cost of glass can be held down. Accordingly, the molar sum (Gd ₂ O ₃ + Ta ₂ O ₅ ) is preferably less than 7.0%, more preferably less than 4.0%, even more preferably less than 1.0%, and even more preferably less than 0.5%. And

The Gd ₂ O ₃ component is an optional component that can increase the refractive index of the glass and increase the Abbe number when it exceeds 0%.
On the other hand, by making the particularly expensive Gd ₂ O ₃ component less than 7.0% among rare earth elements, the material cost of the glass is reduced, so that an optical glass can be produced at a lower cost. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Accordingly, the content of the Gd ₂ O ₃ component is preferably less than 7.0%, more preferably less than 5.0%, still more preferably less than 1.0%, still more preferably less than 0.3%, and still more preferably. Is 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 the glass and increase the devitrification resistance when it exceeds 0%.
On the other hand, since the material cost of glass is reduced by making the expensive Ta ₂ O ₅ component less than 5.0%, an optical glass can be produced at a lower cost. Moreover, since the melting temperature of a raw material becomes low by this and the energy required for melting of a raw material is reduced, the manufacturing cost of optical glass can also be reduced. Accordingly, 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%, still more preferably less than 0.3%, and still more preferably. 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.

By containing more than 0% of the Y ₂ O ₃ component, the material cost of the glass can be suppressed while maintaining a high refractive index and a high Abbe number, and the specific gravity of the glass can be reduced more than other rare earth components. It is an essential ingredient. Therefore, the content of the Y ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, still more preferably 1.7%, still more preferably 2.4%, and even more preferably 3.1%. May be the lower limit.
On the other hand, by setting the content of the Y ₂ O ₃ component to 15.0% or less, a decrease in the refractive index of the glass can be suppressed, and the devitrification resistance of the glass can be enhanced. Therefore, the content of the Y ₂ O ₃ component is preferably 15.0%, more preferably 10.0%, still more preferably 8.0%, and still more preferably 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 Yb ₂ O ₃ component is an optional component that can increase the refractive index of the glass and increase the Abbe number when it exceeds 0%.
On the other hand, by making the content of Yb ₂ O ₃ component to 10.0% or less, since the material cost of the glass is reduced, it can be produced at a lower cost optical glass. This also increases the devitrification resistance of the glass. Therefore, the content of the Yb ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%, still more preferably 0.3%. Less than the upper limit. 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 contents of Ln ₂ O ₃ components (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 is preferable.
In particular, by setting the sum to 10.0% or more, both the refractive index and Abbe number of the glass can be increased. Therefore, it is possible to easily obtain a glass having a desired refractive index and Abbe number. Therefore, the lower limit of the molar sum of the Ln ₂ O ₃ component is preferably 10.0%, more preferably 13.0%, still more preferably 15.5%, and even more preferably 17.0%.
On the other hand, since the liquidus temperature of glass becomes low by making this sum 40.0% or less, devitrification of glass can be reduced. Therefore, the upper limit of the molar sum of the Ln ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, even more preferably 25.0%, and even 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, since the liquidus temperature of glass becomes lower, glass with higher devitrification resistance can be obtained. In particular, as the _Ln 2 _{O 3} component, which contains two or more components including _La 2 _{O 3} component and _Y 2 _{O 3} component, and that it can easily lower the liquidus temperature of the glass, inexpensive optical glass Is preferable in that it can be manufactured.

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 making this ratio exceed 0, the material cost of the glass can be suppressed, and the specific gravity of the glass can be reduced more than other rare earth components. Therefore, the molar ratio Y ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ ) is preferably more than 0, more preferably 0.10, still more preferably 0.15, still more preferably 0.21, and even more preferably Has a lower limit of 0.24.
On the other hand, by making this ratio 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 less than 1.00, more preferably less than 0.85, even more preferably less than 0.75, and even more preferably 0.65. Less than, more preferably less than 0.50.

When the SiO ₂ component is contained in an amount exceeding 0%, the viscosity of the molten glass can be increased, the coloring of the glass can be reduced, and the devitrification resistance can be increased. Accordingly, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably 1.3% or more, still more preferably more than 2.0%, still more preferably 4.0%. It may be super.
On the other hand, when the content of the SiO ₂ component is 15.0% or less, an increase in the glass transition point can be suppressed and a decrease in the refractive index can be suppressed. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 15.0%, more preferably 12.0%, still more preferably 10.0%, and still more 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.

The ZrO ₂ component is an optional component that can increase the refractive index and Abbe number of the glass and can improve the devitrification resistance when it is contained in excess of 0%. Therefore, the content of the ZrO ₂ component may be preferably 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 inclusion 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, still more preferably less than 6.0%, and even more preferably less than 5.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The ZnO component is an optional component that can lower the glass transition point and improve the chemical durability when it exceeds 0%. Accordingly, the content of the ZnO component is preferably 5.0%, more preferably 6.0%, further preferably 11.0%, further preferably 17.0%, and further preferably 20.8%. Also good.
On the other hand, by setting the content of the ZnO component to 40.0% or less, the liquidus temperature can be lowered, and devitrification due to an unnecessary decrease in the glass transition point can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 40.0%, more preferably 35.0%, further preferably 33.0%, further preferably 30.0%, and further preferably 26.0%. To do.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

Li 2 _O component, when ultra containing 0%, which is an optional component that can be lowered glass transition temperature.
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 to reduce devitrification, and the chemical durability can be enhanced. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably 5.0% or less, still more preferably 3.0% or less, and even more preferably less than 1.0%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are optional components that can improve the meltability of the glass, lower the glass transition point, and increase the devitrification resistance when contained over 0%.
On the other hand, by making the content of the Na ₂ O component 15.0% or less and / or making the content of the K ₂ O component 10.0% or less, it is difficult to lower the refractive index of the glass, And devitrification of glass can be reduced. Therefore, the content of the Na ₂ O component is preferably 15.0%, more preferably 10.0%, further preferably 5.0%, and further preferably 3.0%. Further, the content of the K ₂ O component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
The Na ₂ O component and the K ₂ O component may use Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _6, etc. as raw materials. it can.

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 making this total value 5.0% or more, it is possible to easily obtain an optical glass having a higher glass transition point and high chemical durability. Therefore, the molar sum (ZnO + 2 × Li ₂ O) is preferably 5.0%, more preferably 10.0%, still more preferably 15.0%, still more preferably 19.0%, still more preferably 20.0. % Is the lower limit.
On the other hand, when the total value is 45.0% or less, the refractive index and Abbe number of the glass can be hardly lowered. Therefore, the molar sum (ZnO + 2 × Li ₂ O) is preferably 45.0%, more preferably 40.0%, still more preferably 35.0%, still more preferably 30.0%, still more preferably 25.0%. % Is the upper limit.

The sum (molar sum) of the content of Rn ₂ O components (wherein Rn is one or more selected from 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 devitrification of the glass can be reduced. Therefore, the molar sum of the Rn ₂ O component is preferably 20.0%, more preferably 10.0%, still more preferably 6.0%, still more preferably 3.5%, and even more preferably 2.%. Less than 0%.

The MgO component, CaO component, SrO component, and BaO component are optional components that can adjust the refractive index, meltability, and devitrification resistance of the glass when the content exceeds 0%.
On the other hand, by making the content of each of the MgO component, CaO component, SrO component and BaO component 10.0% or less, it becomes easy to obtain a desired refractive index, and glass due to excessive inclusion of these components. Can devitrify. Accordingly, the content of each of the MgO component, CaO component, SrO component and BaO component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
MgO component, CaO component, SrO component and BaO component are MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ etc. as raw materials. Can be used.

  The sum (molar sum) of the content of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 10.0% or less. Thereby, a desired high refractive index can be easily obtained. Therefore, the molar sum of the RO component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably less than 1.0%.

The P ₂ O ₅ component is an optional component that can reduce the liquidus temperature of the glass and increase the devitrification resistance when it contains more than 0%.
On the other hand, when the content of P ₂ O ₅ component to 10.0% or less, the chemical durability of the glass, in particular suppressing a decrease in water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance when it contains more than 0%.
However, since the raw material price of GeO ₂ is high, the production cost increases when the content is large, and the effect of reducing the Gd ₂ O ₃ component, the Ta ₂ O ₅ component, etc. is diminished. Therefore, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, further preferably 3.0%, further preferably 1.0%, and further preferably 0.1%. And 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 optional components that can improve the chemical durability of the glass and improve the devitrification resistance of the molten glass when it is contained in excess of 0%.
On the other hand, by setting the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 15.0% or less, the liquidus temperature of the glass can be lowered to increase 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%, still more preferably 5.0%, and even more preferably 3.0%. Is the upper limit.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like can be used as a raw material.

The TiO ₂ component is an optional component that can increase the refractive index and Abbe number of the glass and increase the devitrification resistance by lowering the liquidus temperature of the glass when it contains more than 0%.
On the other hand, by setting the content of the TiO ₂ component to 20.0% or less, devitrification due to excessive content of the TiO ₂ component can be reduced, and the transmittance of glass with respect to visible light (especially, wavelength of 500 nm or less) is reduced. It can be suppressed. Therefore, the content of the TiO ₂ component is preferably 20.0%, more preferably 15.0%, still more preferably 12.0%, still more preferably 10.0%, still more preferably 5.0%, Preferably, the upper limit is 1.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

Nb ₂ O ₅ component is an optional component that can increase the refractive index of the glass and reduce the Abbe number when it contains more than 0%, and increase 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, devitrification due to excessive content of the Nb ₂ O ₅ component can be reduced, and visible light of the glass (particularly, a wavelength of 500 nm or less). Decrease in the transmittance with respect to can be suppressed. Accordingly, the content of the Nb ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When containing more than 0% of the WO ₃ component, it is possible to increase the refractive index, lower the glass transition point and increase the devitrification resistance of the glass while reducing the coloring of the glass due to other high refractive index components. It is an optional component.
On the other hand, by setting the content of the WO ₃ component to 10.0% or less, the coloring of the glass by the WO ₃ component can be reduced and the visible light transmittance can be increased. Therefore, the content of the WO ₃ component is preferably 10.0%, more preferably 7.0%, and still more preferably 5.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 15.0% or less, the liquidus temperature of the glass can be lowered to increase the devitrification resistance. Therefore, the content of the Bi ₂ O ₃ component is preferably 15.0%, 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 TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it is contained in excess of 0%.
On the other hand, TeO ₂ has a problem that it can be alloyed with platinum when melting a glass raw material in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 15.0%, more preferably less than 10.0%, still more preferably less than 5.0%, and even more preferably less than 3.0%.
TeO ₂ component can use TeO ₂ or the like as a raw material.

When the SnO ₂ component is contained in an amount of more than 0%, the SnO ₂ component is an optional component that can be refined by reducing the oxidation of the molten glass and can increase the visible light transmittance of the glass.
On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, the coloring of the glass due to the reduction of the molten glass and the devitrification of the glass can be reduced. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, more preferably 1.0% or less, and still more preferably less than 0.5%.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component that can degas the molten glass when it contains more than 0%.
On the other hand, when the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.7%, and still more preferably 0.5%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

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

The F component is an optional component that can increase the Abbe number of the glass, lower the glass transition point, and improve the devitrification resistance when the content exceeds 0%.
However, when the F component is contained, the volatilization amount of the F component from the molten glass increases, so that it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass.
Therefore, the content of the F component, that is, the total amount of F substituted with a part or all of one or more oxides of each of the above metal elements is preferably 15.0%. The upper limit is preferably 10.0%, more preferably 5.0%, and most preferably not contained.
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, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

  Other components can be added as necessary within the range not impairing the properties of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is independent of each other. Or, even when it is contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. .

Moreover, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components with high environmental loads, it is desirable that they are not substantially contained, that is, not contained at all except for inevitable mixing.

  Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to be refrained from being used as a harmful chemical material in recent years, and not only in the glass manufacturing process, but also in the processing process and disposal after commercialization. Until then, environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable that these are not substantially contained.

The glass composition of the present invention is not expressed directly in terms of mass% because the composition is expressed in terms of mol% with respect to the total amount of glass in the oxide-converted composition, but is required in the present invention. The composition represented by mass% of each component present in the glass composition satisfying the characteristics generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component from 15.0 to 35.0 wt%,
La ₂ O ₃ component from 25.0 to 50.0 wt%
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 from 0 to 25.0% by weight
Yb ₂ O ₃ component 0 to 25.0 mass%
SiO ₂ component 0 to 8.0 mass%
ZrO ₂ component 0 to 10.0% by mass
ZnO component 0 to 25.0 mass%
Li ₂ O components 0 to 3.0 wt%
Na ₂ O component from 0 to 8.0 wt%
K ₂ O component from 0 to 8.0 wt%
MgO component 0-3.0 mass%
CaO component 0-5.0 mass%
SrO component 0-8.0 mass%
BaO component 0 to 10.0% by mass
P ₂ O ₅ component 0 to 10.0% by weight
GeO ₂ component 0-8.0 mass%
Al ₂ O ₃ component 0 to 10.0% by mass
Ga ₂ O ₃ component 0 to 20.0 wt%
TiO ₂ component 0 to 10.0% by mass
Nb ₂ O ₅ component 0 to 20.0 mass%
WO ₃ component 0-15.0 mass%
Bi ₂ O ₃ component from 0 to 35.0% by weight
TeO ₂ component 0 to 15.0 mass%
SnO ₂ component 0-3.0 wt%
Sb ₂ O ₃ component 0-3.0 mass%
And the total amount as F of the fluoride substituted with one or two or more oxides of each of the above metal elements as 0 to 5.0% by mass

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, the prepared mixture is put into a platinum crucible, and 1100-1500 ° C. in an electric furnace depending on the difficulty of melting the glass composition. It is produced by melting in the temperature range of 2 to 5 hours and homogenizing with stirring, then lowering to an appropriate temperature, casting into a mold, and slow cooling.

[Physical properties]
The optical glass of the present invention preferably has a high refractive index and a high Abbe number (low dispersion). In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.71, and still more preferably 1.73. The refractive index (n _d ) is preferably 1.85, more preferably 1.83, still more preferably 1.81, and still more preferably 1.80. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 42, more preferably 43, and still more preferably 45. The Abbe number (ν _d ) is preferably 60, more preferably 58, and still more preferably 55.
By having such a high refractive index, a large amount of light can be obtained even if the optical element is thinned. In addition, by having such low dispersion, even with a single lens, focus shift (chromatic aberration) due to the wavelength of light is reduced. In addition, by having such low dispersion, for example, when combined with an optical element having high dispersion (low Abbe number), high imaging characteristics and the like can be achieved.
Therefore, the optical glass of the present invention is useful in optical design, and the optical system can be miniaturized and the degree of freedom in optical design can be expanded while achieving particularly high imaging characteristics.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high transmittance of light on the short wavelength side of visible light, and thereby less coloring.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₈₀ ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 500 nm, more preferably 450 nm, and still more preferably 420 nm. The upper limit.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, still more preferably 360 nm, and further preferably 340 nm. And
As a result, the absorption edge of the glass is in the ultraviolet region or the vicinity thereof, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

  The optical glass of the present invention preferably has high devitrification resistance, more specifically, a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1100 ° C., more preferably 1080 ° C., and still more preferably 1060 ° C. As a result, even if the molten glass flows out at a lower temperature, since the crystallization of the produced glass is reduced, devitrification when the glass is formed from the molten state can be reduced, and the optical element using the glass can be reduced. The influence on the optical characteristics can be reduced. In addition, since the temperature range in which the preform material can be stably produced is widened, the preform material can be formed even when the melting temperature of the glass is lowered, and the energy consumed when forming the preform material can be suppressed. 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 approximately 800 ° C. or higher, specifically 850 ° C. or higher, more specifically 900. Often above ℃. In this specification, “liquid phase temperature” means that a 30 cc cullet-like glass sample is put into a platinum crucible in a platinum crucible having a capacity of 50 ml and completely melted at 1250 ° C., and the temperature is lowered to a predetermined temperature. When the glass surface and the presence or absence of crystals in the glass are observed immediately after being held outside for 12 hours and cooled after being taken out of the furnace, it represents the lowest temperature at which no crystals are observed. The predetermined temperature when the temperature is lowered is a temperature in increments of 10 ° C. 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 not more than 630 ° C.
In particular, in an optical glass having a high refractive index and low dispersion as in the present invention, since the optical glass has a glass transition point of more than 580 ° C., crystallization hardly occurs, and thus devitrification during press molding can be reduced. Thus, glass suitable for press molding can be obtained. In particular, the glass having a higher refractive index and a larger Abbe number tends to cause crystallization of the glass, and thus the effect obtained by setting the glass transition point to a temperature range 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 585 ° C., still more preferably more than 590 ° C.
On the other hand, since the optical glass has a glass transition point of 630 ° C. or lower, the glass is softened at a lower temperature, so that the glass can be easily pressed at a lower temperature. In addition, it is possible to extend the life of the mold by reducing oxidation of the mold used for press molding. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 630 ° C., more preferably 628 ° C., and further preferably 625 ° C.
Even when the glass transition point is higher than 580 ° C., for example, by using a molding machine or a mold as disclosed in Japanese Patent Application Laid-Open No. 2007-186384, damage to the surface of the press mold can be reduced, and the mold material Since it is possible to improve the durability of the optical glass, precision press molding of optical glass having a glass transition point exceeding 580 ° C. is generally 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. Thereby, since the mass of an optical element and an optical apparatus using the same is reduced, it can contribute to the weight reduction of an optical apparatus. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.80, and preferably 4.60. The specific gravity of the optical glass of the present invention is generally about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more in many cases.
The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 “Measurement Method of Specific Gravity of Optical Glass”.

[Preform materials and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding was prepared from optical glass, and after performing reheat press molding on this preform, polishing was performed to prepare a glass molded body, or polishing was performed. It is possible to produce a glass molded body by performing precision press molding on a preform, or a preform molded by a known floating molding or the like. In addition, the means for producing the glass molded body is not limited to these means.

  Thus, the optical glass of the present invention is useful for various optical elements and optical designs. Among these, it is particularly preferable to form a preform from the optical glass of the present invention, and perform reheat press molding, precision press molding or the like using this preform to produce an optical element such as a lens or a prism. As a result, preforms with large diameters can be formed, so that the optical elements can be made larger, but when they are used in optical equipment such as cameras and projectors, high-definition and high-precision imaging characteristics and projection characteristics. Can be realized.

Examples of the present invention (No.1~No.74), the composition of Comparative Example (No. A) and reference examples (No.A), as well as the refractive index of these glasses _(n d), Abbe number ([nu Tables 1 to 11 show the results of _d ), glass transition point (Tg), liquid phase temperature, wavelengths (λ ₅ , λ ₈₀ ) at which the spectral transmittance is 5% and 80%, and specific gravity. The following examples are merely for illustrative purposes, and are not limited to these examples.

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

Here, the refractive index of the glass of Example, Comparative Examples and Reference Examples _{(n d)} and Abbe number ([nu _d) was measured according to Japan Optical Glass Industry Society Standard JOGIS01-2003. Here, the refractive index (n _d ) and Abbe number (ν _d ) were determined by measuring the glass obtained at a slow cooling rate of -25 ° C./hr.

  The glass transition point (Tg) of the glass of Examples, Comparative Examples, and Reference Examples was determined by performing measurement using a horizontal expansion measuring device. Here, the sample at the time of measuring used the thing of (phi) 4.8mm and length 50-55mm, and the temperature increase rate was 4 degrees C / min.

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

  The liquid phase temperature of the glasses of the examples, comparative examples and reference examples is as follows: a 30 cc cullet-shaped glass sample is placed in a platinum crucible in a platinum crucible having a capacity of 50 ml and completely melted at 1250 ° C. When the temperature is lowered to any temperature set in increments of 10 ° C. and held for 12 hours, taken out of the furnace and cooled, the glass surface and the presence or absence of crystals in the glass are observed immediately, and no crystals are observed. The lowest temperature was determined.

The specific gravity of the glass of an Example, a comparative example, and a reference example was measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 "Measurement Method of Specific Gravity of Optical Glass".

As shown in the table, the optical glass of the example of the present invention has a molar sum (Gd ₂ O ₃ + Ta ₂ O ₅ ) of less than 7.0%, and thus can be obtained at a lower cost. On the other hand, the glass of the comparative example (No. A) has a high material cost because the molar sum (Gd ₂ O ₃ + Ta ₂ O ₅ ) is 8.353%.

All of the optical glasses of the examples of the present invention had a glass transition point (Tg) of more than 580 ° C. and 630 ° C. or less, more specifically 590 ° C. or more and 630 ° C. or less, and were in a desired range. On the other hand, as for the glass of a comparative example (No. A) and a reference example (No. a), all had a glass transition point (Tg) exceeding 630 degreeC.
Further, the optical glasses of the examples of the present invention all had a liquidus temperature of 1100 ° C. or lower, more specifically 1080 ° C. or lower, and were within a desired range.
For this reason, the optical glass of the embodiment of the present invention can reduce devitrification at the time of glass production and press molding without using components with high material costs such as Gd ₂ O ₃ component and Ta ₂ O ₅ component. Became clear.

In addition, in the optical glasses of the examples of the present invention, λ ₈₀ (wavelength at 80% transmittance) was 500 nm or less, more specifically 450 nm or less. In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength at 5% transmittance) was 400 nm or less, more specifically, 340 nm or less. For this reason, it became clear that the optical glass of the Example of this invention has the high transmittance | permeability of the light of visible short wavelength, and is hard to color.

All of the optical glasses of the examples of the present invention had a refractive index (n _d ) of 1.70 or more, more specifically 1.73 or more, and were within a desired range. These optical glasses, with both is the Abbe number ([nu _d) is 42 or more, the Abbe's number ([nu _d) is 60 or less, at 54 or less and more particularly, were within the desired range .

The optical glasses of the examples of the present invention all had a specific gravity of 5.00 [g / cm ³ ] or less, more specifically 4.60 [g / cm ³ ] or less. Therefore, it became clear that the optical glass of the Example of this invention has small specific gravity.

Therefore, the optical glass of the example of the present invention has high transmittance at a visible short wavelength and high devitrification resistance, while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It became clear that press molding by heat softening was easy and the specific gravity was small.

  Furthermore, using the optical glass of the example of the present invention, after performing reheat press molding, grinding and polishing were performed to process into the shape of a lens and a prism. Further, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded into the shape of a lens and a prism. In either case, the glass after heat softening did not cause problems such as opacification and devitrification, and could be stably processed into various lens and prism shapes.

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

Claims (20)

Containing 35.0% or more and 65.0% or less of B ₂ O ₃ component and 5.0% or more and 30.0% or less of La ₂ O ₃ component in mol%, and the molar sum (Gd ₂ O ₃ + Ta ₂ O ₅₎ is less than 7.0%, has 1.70 or more of refractive index _{(n d),} the optical glass having a 42 or 60 following an Abbe number ([nu _d). In mol%
The optical glass according to claim 1, wherein Gd ₂ O ₃ component is 0 to less than 7.0% Ta ₂ O ₅ component is 0 to less than 5.0%. In mol%
Y ₂ O ₃ component 0 to 15.0%
Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to claim 1 or 2. _2. The molar sum of Ln ₂ O ₃ components (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. 4. The optical glass according to any one of items 1 to 3. The optical glass according to 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. The optical glass according to any one of claims 1 to 5, wherein the content of the SiO ₂ component is 15.0% or less in terms of mol%. The optical glass according to claim 1, 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 claims 1 to 7, wherein the optical glass contains a ZnO component in a mol% of 5.0% or more and 40.0% or less. In mol%
Li ₂ O component 0 to 10.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 10.0%
The optical glass according to any one of claims 1 to 8. The optical glass according to claim 1, wherein a molar sum (ZnO + 2 × Li ₂ O) is 5.0% or more and 45.0% or less. The optical glass according to any one of claims 1 to 10, wherein a molar sum of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 20.0% or less. 0% to 10.0% MgO component in mol%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
BaO component 0 to 10.0%
The optical glass according to any one of claims 1 to 11.   The optical glass according to any one of claims 1 to 12, wherein a molar sum of RO components (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is 10.0% or less. _P 2 _{O 5} component from 0 to 10.0% by mole%
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 15.0%
Ga ₂ O ₃ component from 0 to 15.0%
TiO ₂ component 0-20.0%
Nb ₂ O ₅ component 0 to 10.0%
WO ₃ components 0 to 10.0%
Bi ₂ O ₃ component 0 to 15.0%
TeO ₂ component 0-15.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-1.0%
And
The content as F of the fluoride which substituted a part or all of the 1 type (s) or 2 or more types of said each metal element as an oxide is 0-15.0 mol%. Optical glass. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.70 or more and 1.85 or less and an Abbe number (ν _d ) of 42 or more and 55 or less.   The optical glass according to claim 1, which has a liquidus temperature of 1100 ° C. or lower.   A preform material comprising the optical glass according to any one of claims 1 to 16.   An optical element produced by press-molding the preform material according to claim 17.   The optical element which uses the optical glass in any one of Claims 1-16 as a base material.   An optical apparatus comprising the optical element according to claim 18.