JP6164923B2 - Optical glass and optical element - Google Patents

Description

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

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

Among optical glasses for producing optical elements, an Abbe number (not less than 20 and not more than 40) having a refractive index (n _d ) of 1.85 or more, which can reduce the weight and size of the entire optical system. There is a great demand for high refractive index glasses having ν _d ). As such a high refractive index glass, glass compositions represented by Patent Documents 1 and 2 are known.

JP 2012-162448 A JP 2010-030879 A

  However, in the glass disclosed in Patent Document 1, since the transmittance of visible light on the short wavelength side is low, the glass is colored yellow. For this reason, the glasses disclosed in Patent Documents 1 and 2 are not suitable for applications that transmit light in the visible region. Therefore, there has been a demand for an optical glass having a higher refractive index and a desired Abbe number while having a high transmittance for light on the short wavelength side of visible light.

The present invention has been made in view of the above problems, and the object thereof is to have a refractive index (n _d ) of 1.85 or more and an Abbe number (ν _d ) of 20 or more and 40 or less. However, an object of the present invention is to provide an optical glass having high visible light transmittance, an optical element using the optical glass, and a method for producing a glass molded body.

As a result of intensive studies and studies to solve the above problems, the present inventors have found that a SiO ₂ component or a B ₂ O ₃ component, a La ₂ O ₃ component, a Gd ₂ O ₃ component, a Y ₂ O ₃ component, and By using at least one of the Yb ₂ O ₃ components in combination, and setting the content of the F component and the total amount of the Nb ₂ O ₅ component and the TiO ₂ component within a predetermined range, a high refractive index and low While the Abbe number was obtained, it was found that the coloring of the glass was reduced and the devitrification of the glass was reduced, and the present invention was completed.
Specifically, the present invention provides the following.

(1) By mass%, the SiO ₂ component and the B ₂ O ₃ component are 5.0 to 40.0% in total, and the Ln ₂ O ₃ component is 20.0 to 70.0% in total (Ln is Y 1 or more selected from the group consisting of La, Gd, and Yb), and the content of the F component is more than 0% to 20.0% by mass% of the outer ratio with respect to the mass of the oxide, and Nb ₂ An optical glass in which the total amount of the O ₅ component and the TiO ₂ component is 0 to 50.0%, the refractive index is 1.85 or more, and the wavelength showing 70% transmittance at a thickness of 10 mm is 450 nm or less.

(2) The optical glass according to (1), containing 5.0 to 40.0% of a B ₂ O ₃ component by mass%, and the content of the SiO ₂ component being 0 to 20.0%.

(3) The content of La ₂ O ₃ component is 10.0 to 70.0% by mass%, and the content of Gd ₂ O ₃ component is 0 to 30.0% as described in (1) or (2) Optical glass.

(4)% by weight _Y 2 _{O 3} component from 0 to 30.0%,
Yb ₂ O ₃ component 0 to 30.0%
The optical glass according to any one of (1) to (3).

(5) The optical glass according to any one of (1) to (4), wherein the content of the TiO ₂ component is 30.0% by mass or less.

(6) The optical glass according to any one of (1) to (5), wherein the content of the Nb ₂ O ₅ component is 50.0% by mass or less.

(7) By mass%
ZrO ₂ component 0 to 20.0%
Ta ₂ O ₅ component 0 to 20.0%
The optical glass according to any one of (1) to (6).

(8) Li ₂ O component in mass% 0 to 10.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 15.0%
The optical glass according to any one of (1) to (7).

(9) Any of (1) to (8), wherein the R ₂ O component (wherein R is one or more selected from the group consisting of Li, Na, and K) is 20.0% or less The optical glass described.

(10) MgO component in mass% 0 to 10.0%
CaO component 0 to 15.0%
SrO component 0 to 15.0%
BaO component 0 to 20.0%
ZnO component 0 to 20.0%
The optical glass according to any one of (1) to (9).

  (11) The mass sum of the MO component (wherein M is one or more selected from the group consisting of Mg, Ca, Sr, Ba and Zn) is 20.0% or less. (1) to (10) Any one of the optical glasses.

(12)% by weight _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%
WO ₃ component 0-20.0%
Bi ₂ O ₃ component 0 to 30.0%
TeO ₂ component 0 to 30.0%
SnO ₂ component 0 to 10.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) to (11).

  (13) The optical glass according to any one of (1) to (12), which has an Abbe number (νd) of 20 to 40.

(14) The optical glass according to any one of (1) to (13), wherein the Pt content with respect to the glass mass is 20 ppm or less and the ratio of Pt ²⁺ is 80% or less.

  (15) An optical element comprising the optical glass according to any one of (1) to (14).

  (16) A method for producing a glass molded body, which uses the optical glass according to any one of (1) to (14) and press-molds the softened optical glass in a mold.

According to the present invention, an optical glass having a high visible light transmittance can be obtained while having a refractive index (n _d ) of 1.85 or more and an Abbe number (ν _d ) of 20 or more and 40 or less, As a result, the optical element using this optical glass and the manufacturing method of a glass forming body can be provided.

It is the graph which compared the spectral transmittance of the glass of Example 12 and Comparative Example 1. FIG.

The optical glass of the present invention is mass%, and the SiO ₂ component and the B ₂ O ₃ component are combined in a total amount of 5.0 to 40.0%, and the Ln ₂ O ₃ component is combined in a total amount of 20.0 to 70.0%. (Ln is at least one selected from the group consisting of Y, La, Gd and Yb), and contains an F component in an externally divided mass% with respect to the oxide-based mass of more than 0% to 20.0% In addition, the total amount of the Nb ₂ O ₅ component and the TiO ₂ component is 0 to 50.0%, the refractive index is 1.85 or more, and the wavelength indicating 70% transmittance at a thickness of 10 mm is 450 nm or less. is there. By containing the F component, the internal transmittance is increased by reducing the coloring of the glass. Moreover, based on at least one of the SiO ₂ component and the B ₂ O ₃ component, and adjusting the total amount of the Ln ₂ O ₃ component and the total amount of the Nb ₂ O ₅ component and the TiO ₂ component, A stable glass having a refractive index (n _d ) and an Abbe number (ν _d ) is obtained. Therefore, it is possible to obtain an optical glass having a high visible light transmittance while having a refractive index (n _d ) of 1.85 or more and an Abbe number (ν _d ) of 20 or more and 40 or less.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise specified in the present specification, the contents of the respective components are all expressed in mass% with respect to the total mass of the glass in terms of oxide. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as a raw material of the glass component of the present invention are all decomposed and changed into an oxide when melted. It is the composition which described each component contained in glass by making the total mass of the said production | generation oxide into 100 mass%.

The content of B ₂ O ₃ component and SiO ₂ component is 5.0 to 40.0% in total.
In particular, by making the sum of these contents 5.0% or more, it is possible to suppress a decrease in devitrification resistance due to the lack of the B ₂ O ₃ component or the SiO ₂ component. Accordingly, the lower limit of the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 5.0%, more preferably 8.0%, still more preferably 10.0%, and even more preferably 12.0%.
On the other hand, by making this sum 40.0% or less, a decrease in refractive index due to excessive inclusion of these components can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the upper limit of the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 40.0%, more preferably 35.0%, further preferably 30.0%, and further preferably 23.0%.

Sum (mass sum) of contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is 20.0% or more and 70.0% or less It is.
In particular, when the sum is 20.0% or more, the dispersion of the glass can be reduced. Therefore, the lower limit of the mass sum of the Ln ₂ O ₃ component is preferably 20.0%, more preferably 30.0%, still more preferably 40.0%, and even more preferably 48.0%.
On the other hand, by setting the sum to 70.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. Therefore, the upper limit of the mass sum of the Ln ₂ O ₃ component is preferably 70.0%, more preferably 65.0%, and still more preferably 62.0%.

By containing more than 0% of the F component, reduction of Ti ions (Ti ⁴⁺ ) derived from the TiO ₂ component described later and platinum ions (Pt ⁴⁺ ) described later can be suppressed. The internal transmittance can be increased. In addition, the F component has the effects of lowering the melting temperature of the glass, increasing the stability of the glass, and reducing the dispersion (increasing the Abbe number). Therefore, the content of the F component on an outer basis with respect to the mass based on the oxide is preferably more than 0%, more preferably more than 0.10%, and still more preferably more than 0.20%.
On the other hand, when the content of the F component is 20.0% or less, the occurrence of striae on the glass can be reduced, and the glass can be made hard to devitrify. Therefore, the content of the F component in an outer ratio with respect to the mass based on the oxide is preferably 20.0%, more preferably 10.0%, still more preferably 6.0%, and even more preferably 3.0%. The upper limit.
The F component can be contained in the glass using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ , LaF ₃ or the like as a raw material.

  The content of the F component in this specification is based on the assumption that all of the cation components constituting the glass are made of oxides combined with oxygen that balances the charge, and the total mass of the glass made of these oxides is 100. % Represents the mass of the F component in mass% (externally divided mass% with respect to the oxide-based mass).

The total content of the Nb ₂ O ₅ component and the TiO ₂ component is 50.0% or less. Thereby, the coloring of the glass can be reduced to increase the visible light transmittance, and the Abbe number of the glass can be suppressed from being lowered more than necessary. Further, devitrification due to excessive inclusion of these components can be suppressed. Therefore, the upper limit of the mass sum (Nb ₂ O ₅ + TiO ₂ ) is preferably 50.0%, more preferably 40.0%, still more preferably 30.0%, and even more preferably 24.0%.
On the other hand, _Nb 2 _{O 5} component and TiO ₂ component may be ultra containing 0% in total. Thereby, the refractive index of glass can be raised, Abbe's number can be adjusted low, and devitrification resistance can be improved. Therefore, the mass sum (Nb ₂ O ₅ + TiO ₂ ) is preferably more than 0%, more preferably more than 2.0%, still more preferably more than 4.0%, still more preferably more than 7.0%, still more preferably Over 9.0%.

The B ₂ O ₃ component is an optional component that can enhance the devitrification resistance of the glass and reduce the dispersion of the glass when it is contained in an amount of more than 0%. Therefore, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably 5.0%, still more preferably 8.0%, and even more preferably 9.0%.
On the other hand, by making the content of the B ₂ O ₃ component 40.0% 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 40.0%, more preferably 30.0%, still more preferably 20.0%, and even more preferably 17.0%.
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 SiO ₂ component is an optional component that, when contained over 0%, can increase the viscosity of the molten glass, reduce the coloration of the glass, and increase the devitrification resistance. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 2.0%.
On the other hand, by setting the content of the SiO ₂ component to 20.0% 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 20.0%, more preferably 15.0%, still more preferably 10.0%, and even more preferably 7.0%.
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

The La ₂ O ₃ component is an optional component that can increase the refractive index of the glass and reduce the dispersion (increase the Abbe number) when it exceeds 0%. Accordingly, the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 20.0%, still more preferably 25.0%, still more preferably 30.0%, and even more preferably 35.0%. More preferably, the lower limit may be 41.0%, more preferably 45.0%.
On the other hand, the devitrification resistance of the glass can be enhanced by setting the content of the La ₂ O ₃ component to 70.0% or less. Therefore, the content of the La ₂ O ₃ component is preferably 70.0%, more preferably 60.0%, further preferably 55.0%, and further preferably 52.0%.
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 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 reducing the Gd ₂ O ₃ component, which is particularly expensive among rare earth elements, to 30.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. 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 30.0%, more preferably 20.0%, and still more preferably 10.0%.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component that can increase the Abbe number and suppress an increase in the material cost of the glass when it is contained in excess of 0%. Accordingly, the content of the Y ₂ O ₃ component is preferably more than 0%, more preferably 2.0%, and even more preferably 4.0%.
On the other hand, by setting the content of the Y ₂ O ₃ component to 30.0% or less, a decrease in the refractive index of the glass can be suppressed and the devitrification resistance of the glass can be enhanced. Therefore, the content of the Y ₂ O ₃ component is preferably 30.0%, more preferably 20.0%, and even more preferably 13.0%.
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 reduce the dispersion when it exceeds 0%.
On the other hand, the devitrification resistance of glass can be improved by setting the content of the Yb ₂ O ₃ component to 30.0% or less. Therefore, the content of the Yb ₂ O ₃ component is preferably 30.0%, more preferably less than 20.0%, even more preferably less than 10.0%, and even more preferably less than 5.0%. .
As the Yb ₂ O ₃ component, Yb ₂ O 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 of the glass, adjust the Abbe number to be low, and increase the devitrification resistance when it is contained in excess of 0%. In particular, the TiO ₂ component is a component that can enhance the devitrification resistance even when a large amount of a rare earth component, particularly a Ln ₂ O ₃ component is contained, and thus contributes to a higher refractive index of glass. It is a possible component. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 2.0%, still more preferably more than 2.5%, still more preferably 4.0%. It may be super.
On the other hand, by setting the content of TiO ₂ to 30.0% or less, the coloring of the glass can be reduced to increase the visible light transmittance, and the Abbe number can be prevented from being lowered more than necessary. Further, devitrification due to excessive inclusion of the TiO ₂ component can be suppressed. Therefore, the content of the TiO ₂ component is preferably 30.0%, more preferably 25.0%, further preferably 20.0%, and further preferably 18.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The Nb ₂ O ₅ component is an optional component that can increase the refractive index of the glass and increase the devitrification resistance when it exceeds 0%. Therefore, the content of the Nb ₂ O ₅ component may be preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 2.0%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 50.0% or less, it is possible to reduce the devitrification resistance of the glass due to the excessive content of the Nb ₂ O ₅ component and the transmittance of visible light. Can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 50.0%, more preferably 40.0%, still more preferably 30.0%, still more preferably 25.0%, and even more preferably 18.0%. More preferably, the upper limit is 14.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When the ZrO ₂ component is contained in an amount of more than 0%, it can contribute to a higher refractive index and a lower dispersion of the glass, and the devitrification resistance of the glass can be improved. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 1.0%, and even more preferably more than 3.0%.
On the other hand, by making the ZrO ₂ component 20.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to the excessive inclusion of the ZrO ₂ component. Accordingly, the content of the ZrO ₂ component is preferably 20.0%, more preferably 15.0%, and still more preferably 9.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ 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, by reducing the expensive Ta ₂ O ₅ component to 20.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. 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. Therefore, the content of the Ta ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, even more preferably 10.0%, still more preferably 8.0%, and even more preferably 5.0%. More preferably, the upper limit is 3.0%, more preferably 1.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Li ₂ O component, the Na ₂ O component, and the K ₂ O component are optional components that can improve the meltability of the glass and lower the glass transition point when containing more than 0%. Among Na 2 _O component and K _{2 O} ingredients, it is also a component enhances devitrification resistance of the glass. Here, by making the content of the Li ₂ O component 10.0% or less and / or making each content of the Na ₂ O component and the K ₂ O component 15.0% or less, It is difficult to lower the refractive index and the devitrification resistance can be improved. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less. The content of each of Na ₂ O component and _{K 2} O component is preferably 15.0% or less, more preferably less than 10.0%, more preferably less than 5.0%.
In particular, by setting the content of the Li ₂ O component to 3.0% or less, the viscosity of the glass increases, so that even when the F component is contained, the striae of the glass can be reduced. Therefore, particularly from the viewpoint of reducing the striae of the glass, the content of the Li ₂ O component is preferably 3.0%, more preferably 1.0%, and even more preferably 0.5%.
Li ₂ O component, Na ₂ O component and K ₂ O component are Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF as raw materials. , KHF ₂ , K ₂ SiF ₆ or the like can be used.

The total amount of R ₂ O components (wherein R is one or more selected from the group consisting of Li, Na and K) is preferably 20.0% or less. Thereby, the fall of the refractive index of glass can be suppressed and devitrification resistance can be improved. Therefore, the mass sum of the R ₂ O component is preferably 20.0% or less, more preferably less than 10.0%, and even more preferably less than 5.0%.

The MgO component is an optional component that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when it is contained in an amount exceeding 0%.
On the other hand, by setting the content of the MgO component to 10.0% or less, it is possible to suppress a decrease in refractive index and a decrease in devitrification resistance due to an excessive content of components. Therefore, the content of the MgO component is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, and still more preferably 3.0%.
As the MgO component, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

A CaO component, a SrO component, and a BaO component are optional components that can improve the meltability of the glass raw material and the devitrification resistance of the glass when contained in excess of 0%.
On the other hand, excessive content of these components by making each content of CaO component and SrO component 15.0% or less and / or making BaO component content 20.0% or less Therefore, it is possible to suppress a decrease in refractive index and a decrease in devitrification resistance. Accordingly, the content of each of the CaO component and the SrO component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 8.0%, and even more preferably less than 5.0%. . The content of the BaO component is preferably 20.0% or less, more preferably less than 10.0%, still more preferably less than 8.0%, and still more preferably less than 5.0%.
As the CaO component, SrO component, and BaO component, CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF _{2 and the} like can be used as raw materials.

The ZnO component is an optional component that can lower the glass transition point and increase chemical durability when it is contained in excess of 0%.
On the other hand, by setting the content of the ZnO component to 20.0% or less, a decrease in the refractive index of the glass and a decrease in the devitrification resistance can be suppressed. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striae to glass can be reduced. Accordingly, the content of the ZnO component is preferably 20.0% or less, more preferably less than 10.0%, and even more preferably less than 8.0%.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

  The total content (mass sum) of MO components (wherein M is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 20.0% or less. Thereby, the fall of the refractive index of glass and the fall of devitrification resistance by containing excessive MO component can be suppressed. Therefore, the mass sum of the MO component is preferably 20.0% or less, more preferably 10.0% or less, and still more preferably 8.0% or less.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances devitrification resistance of the glass.
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 8.0%, still 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%.
On the other hand, by making the content of the feed is expensive GeO ₂ to 10.0% or less, it can reduce material costs of the glass. Therefore, the content of the GeO ₂ component is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, and still more preferably 3.0%.
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 increase the chemical durability of the glass and increase the devitrification resistance of the glass when contained in excess of 0%.
On the other hand, by making each content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 15.0% or less, a decrease in the devitrification resistance of the glass due to the excessive content thereof can be suppressed. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably less than 5.0%.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like can be used as a raw material.

The WO ₃ component is an optional component that can increase the refractive index, lower the glass transition point, and increase the devitrification resistance when it contains more than 0%. Therefore, the content of the WO ₃ component may be preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 0.6%.
On the other hand, by making the content of the WO ₃ component 20.0% or less, the coloring of the glass by the WO ₃ component can be reduced and the visible light transmittance can be increased. Therefore, the content of the WO ₃ component is preferably 20.0% or less, more preferably less than 10.0%, and still more preferably less than 5.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

A Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 30.0% or less, the devitrification resistance of the glass can be increased, and the coloring of the glass can be reduced to increase the visible light transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 30.0% or less, more preferably less than 20.0%, still more preferably less than 10.0%, and even more preferably less than 5.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it is contained in excess of 0%.
However, TeO ₂ has a problem that it can be alloyed with platinum when a glass raw material is melted in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 30.0% or less, more preferably less than 20.0%, even more preferably less than 10.0%, and even more preferably less than 5.0%.
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 making the content of the SnO ₂ component 10.0% or less, it is possible to reduce the coloration of the glass due to the reduction of the molten glass and the devitrification of the glass. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

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

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

<About ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

  Other components 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 cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component from 10.0 to 55.0 mol%, and _La 2 _{O 3} component from 5.0 to 35.0 mol%,
And SiO ₂ component 0 to 45.0 mol%,
Gd ₂ O ₃ component 0 to 15.0 mol%,
Nb ₂ O ₅ component 0 to 25.0 mol%,
TiO ₂ component 0-45.0 mol%,
Y ₂ O ₃ component 0 to 20.0 mol%,
Yb ₂ O ₃ component 0 to 15.0 mol%,
ZrO ₂ component 0 to 25.0 mol%,
Ta ₂ O ₅ component from 0 to 8.0 mol%,
Li ₂ O component from 0 to 40.0 mol%,
Na ₂ O component from 0 to 30.0 mol%,
K ₂ O component from 0 to 25.0 mol%,
MgO component 0-35.0 mol%,
CaO component 0-35.0 mol%,
SrO component 0 to 30.0 mol%,
BaO component 0 to 20.0 mol%,
ZnO component 0 to 30.0 mol%,
P ₂ O ₅ component 0 to 10.0 mol%,
GeO ₂ component 0 to 15.0 mol%,
Al ₂ O ₃ component 0 to 20.0 mol%,
Ga ₂ O ₃ component from 0 to 15.0 mol%,
WO ₃ components 0 to 15.0 mol%,
Bi ₂ O ₃ component 0 to 10.0 mol%,
TeO ₂ component 0-25.0 mol%,
SnO ₂ component 0 to 10.0 mol%, or Sb ₂ O ₃ component 0 to 0.8 mol%
The total amount of fluoride as a substitute for part or all of one or more oxides of each of the above metal elements as more than 0% to 30 mol%

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

[Physical properties]
The optical glass of the present invention has a high visible light transmittance, in particular, a high transmittance for light on the short wavelength side of the visible light, thereby reducing coloration.
In particular, when the optical glass of the present invention is represented by the internal transmittance of the glass, the wavelength (λ ₇₀ ) indicating the spectral transmittance of 70% in the sample with a thickness of 10 mm of the optical glass is preferably 450 nm, more preferably 440 nm, Preferably, the upper limit is 430 nm. As a result, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and particularly the transmittance (transparency) of the glass with respect to light on the short wavelength side in the visible region is enhanced. It can be preferably used as a material for the element.

The optical glass of the present invention preferably has a high refractive index and an Abbe number in a predetermined range. In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.85, more preferably 1.88, and still more preferably 1.90. The upper limit of this refractive index is preferably 2.20, more preferably 2.10, and even more preferably 2.00. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 20, more preferably 23, still more preferably 27, the lower limit, preferably 40, more preferably 38, still more preferably 37. .
The optical glass of the present invention having such a refractive index and Abbe number is useful in optical design, and the optical system can be miniaturized while achieving particularly high imaging characteristics. Can expand the degree.

  The optical glass of the present invention preferably has high devitrification resistance when the glass is formed from a molten state. Thereby, since stability of glass is improved and crystallization is reduced, an adverse effect on optical characteristics, particularly transmittance, of an optical element manufactured from glass can be reduced.

In the optical glass of the present invention, it is preferable that the content of Pt with respect to the glass mass is 20 ppm or less, and the ratio of Pt ^{2+ in} the total platinum component contained in the glass is 80% or less. When the optical glass of the present invention is melted in a platinum crucible, platinum ions such as Pt ²⁺ are often mixed into the glass because platinum contained in the crucible reacts with the glass melt. Since the fall of the visible region transmittance | permeability of glass is suppressed by restraining content of Pt and the ratio of Pt ^<2+ > in the above-mentioned range, optical glass preferable as a material of an optical element can be obtained. In particular, in the present invention, by using fluoride as a glass raw material, oxidation of Pt ²⁺ to Pt ⁴⁺ proceeds, so that a glass having a low Pt content and a low Pt ²⁺ ratio can be obtained. This is presumed to be one of the reasons why a high visible region transmittance is obtained in the optical glass of the present invention.
The content of Pt contained in the optical glass can be obtained by decomposing a crushed glass sample with a mixed acid composed of HF, HClO ₄ , HNO ₃ , HCl, etc., and heating and evaporating this to dryness. It can be measured by analyzing the salt added with nitric acid using an ICP mass spectrometer.
In addition, the ratio of Pt ²⁺ can be measured by performing high energy irradiation on a glass sample and analyzing using EXAFS (broad-area X-ray absorption fine structure).

[Glass molding and optical element]
A glass molded body can be produced from the produced optical glass by means of, for example, polishing or molding press molding such as reheat press molding or precision press molding. That is, a glass molded body is manufactured by performing mechanical processing such as grinding and polishing on optical glass, or glass molding is performed by performing a polishing process after performing reheat press molding on a preform manufactured from optical glass. A glass molded body can be produced by producing a body, or by performing precision press molding on a preform produced by polishing or a preform formed by known float forming or the like. In addition, the means for producing the glass molded body is not limited to these means.

  As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferable to use them for optical elements such as lenses and prisms. This makes it possible to form a glass molded body with a large diameter, so that the optical elements can be enlarged, but with high definition and high precision imaging characteristics and projection when used in optical equipment such as cameras and projectors. The characteristics can be realized.

Composition of Examples (No. 1 to No. 17) and Comparative Example (No. 1) of the present invention, refractive index (n _d ), Abbe number (ν _d ), and spectral transmittance are 70%. The wavelength (λ ₇₀ ) is shown in Tables 1 to 3. The following examples are merely for illustrative purposes, and are not limited to these examples.

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

The refractive index (n _d ) and Abbe number (ν _d ) of the glass of the examples and comparative examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. In addition, the glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

The transmittance | permeability of the glass of an Example and a comparative 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 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 ₇₀ (wavelength at a transmittance of 70%) was obtained.

In the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 450 nm or less, and more specifically, 430 nm or less. On the other hand, in the glass of the comparative example of the present invention, λ ₇₀ exceeded 430 nm. This is because the spectral transmittance of the glass of the example (No. 12) is obtained from a graph comparing the spectral transmittances of the glass of the example (No. 12) and the comparative example (No. 1) shown in FIG. In particular, in the wavelength range of 350 to 450 nm, it is clear from the fact that it is higher than that of the comparative example (No. 1).
For this reason, it became clear that the optical glass of the Example of this invention has the transmittance | permeability with respect to visible light higher than the glass of a comparative example, and there is little coloring.

Each of the optical glasses of the examples of the present invention has a refractive index (n _d ) of 1.85 or more, more specifically 1.89 or more, and this refractive index (n _d ) is 2.20 or less. Was within the desired range.

The optical glasses of the examples of the present invention each have an Abbe number (ν _d ) of 20 or more, more specifically 29 or more, and this Abbe number (ν _d ) of 40 or less, more specifically 37. And within the desired range.

Therefore, it was revealed that the optical glass of the example of the present invention has a high transmittance for visible light while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges.

Further, the optical glass of the example of the present invention was obtained by decomposing a crushed glass sample using a mixed acid composed of HF, HClO ₄ , HNO ₃ , HCl, and the like, and heating and evaporating this to dryness. Pt content was measured by analyzing the salt added with nitric acid using an ICP mass spectrometer. As a result, in any of the examples, it was confirmed that the Pt content relative to the glass mass was 6 ppm or less.
Moreover, about the optical glass of the Example of this invention, the ratio of Pt ^<2+> contained in all the platinum components by irradiating a glass sample with high energy and performing the analysis using EXAFS (wide area X-ray absorption fine structure). Was measured. As a result, in any of the examples, it was confirmed that the ratio of Pt ²⁺ contained in the total platinum component was 80% or less.
From these facts, the Pt content of the optical glass of the present invention is small and the ratio of Pt ²⁺ contained in the total platinum component is low, which is one reason why the optical glass of the present invention has a high visible light transmittance. It is assumed that there is.

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

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

Claims (3)

% By mass based on oxide,
SiO ₂ component Over 0% to 20%
B ₂ O ₃ component 9.0-20.0%
La ₂ O ₃ component 30.0-60.0%
TiO ₂ component more than 1.0% to 9.513%
Y ₂ O ₃ component 4.0-20.0%
Gd ₂ O ₃ component 0 to 2.006%
ZrO ₂ component 0 to 15.0%
Ta ₂ O ₅ component 0-1.0%
Containing
Does not contain As ₂ O ₃ component,
SiO ₂ component and B ₂ O ₃ component are combined in a total amount of 10.0 to 30.0 %, and Ln ₂ O ₃ component is combined in a total amount of 40.0 to 70.0% (Ln is derived from Y, La, Gd and Yb) One or more selected from the group consisting of), and containing an F component of more than 0% to 3.0 % by mass% based on the mass based on the oxide, Nb ₂ O ₅ component and TiO ₂ component The total amount of A is more than 7% to 30.0 %, the refractive index is 1.88 or more, has an Abbe number (νd) of 27 to 37, and exhibits a transmittance of 70% at a thickness of 10 mm. Optical glass having a wavelength of 450 nm or less. An optical element comprising the optical glass according to claim 1 . The manufacturing method of the glass forming body which press-molds in the metal mold | die with respect to the said optical glass softened using the optical glass of Claim 1 .

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